Happy New Year

My Wishes in 2010

God gives You…

12 Month of Happiness,

52 Weeks of Fun,

365 Days Success,

8760 Hours Good Health,

52600 Minutes Good Luck,

3153600 Seconds of Joy…and that’s all! ”


IT’S NEW YEAR

Time to address
a new year
…. enter
deal with the project at hand
yet resolve not to dwell on past
never stop dreaming
even on the last exhale
and find it in your heart
to forgive
then you will be forgiven in likeness
try
smile,
even when sad
this provokes the inner smile
to surface
take each day
as it’s dealt
and be thankful for the wealth
mother nature doles
now take a deeeeeeeeep
meditative breath
you’re alive … aren’t you?

Tennis on the Burj

The Burj is the worlds only 7 Star Hotel. I guess it earned one of its stars by having the worlds highest tennis court on its roof! Watch Andre Agassi and Roger Federer play a friendly game on the roof of the Burj. What if you tripped and fell? You’d certainly see stars then. There is a safety net on the sides though.

Awesome view!

I wonder where that ball landed. It probably ended up on the beach or into the ocean. Nice job polluting the ocean with tennis balls, Andre. Next some whale is going to get a tennis ball stuck in its blow hole.

It’s almost tempting to use those nets as a trampoline

Finally, the Burj hotel in Dubai. Someone told me that there is a large fee just to get in and long around. grr. Rich people stink.

Getting Along With Your Teachers

Your Maths teacher wears clothes from 1982 and always mispronounces your name. Your English teacher loves to start classes with pop quizzes. It can be hard to think of these givers of grades as real people. But they eat nasi lemak, drink teh tarik, watch movies, and enjoy sports on the weekends, just like you.

So how can you get along with your teachers? Here are some tips.

Why Work on Good Relationships With Teachers?

A good relationship with a teacher today may help you in the future. You will need teachers' written recommendations to apply to a college or for a job after school. And if you're thinking about going into a career in science, who better to ask about the field than your science teacher?

Teachers are often plugged into the community and may be the first to find out about local competitions, activities, or contests. They also may know about scholarships.

Teachers are another group of adults in your life who can look out for you, guide you, and provide you with an adult perspective. Many are willing to answer questions, offer advice, and help with personal problems.

Developing Good Teacher-Student Relationships

We all have our favourite teachers — those who seem truly interested and treat us as intelligent beings. But what about teachers we don't know as well (or even don't like much)?

You can do lots of things to get a good connection going with your teacher. First, do the obvious stuff: show up for class on time, with all assignments completed. Be alert, be respectful, and ask questions.

Show an interest in the subject. Obviously, your teachers are really interested in their subjects or they wouldn't have decided to teach them! Showing the teacher that you care — even if you're not a math whiz or fluent in English — sends the message that you are a dedicated student.

You can also schedule a private conference during a teacher's free period. Use this time to get extra help, ask questions, inquire about a career in the subject, or talk about your progress in class. You may be surprised to learn that your teacher is a bit more relaxed one-on-one than when lecturing in front of the whole class.

It is possible to try too hard, though. Here are some things to avoid when trying to establish a relationship with your teacher:

Not being sincere. Teachers sense when your only motivation is to get special treatment, a college reference, or a recommendation.

Trying to be teacher's pet. Your behaviour will come off as phony and your classmates may start to resent you.

Giving extravagant gifts. It's OK to offer a small token of appreciation to teachers if they've been helpful to you. But flashy, expensive items could send the wrong message, and a teacher is usually not allowed to accept anything expensive.

Common Teacher-Student Problems

If you're having problems with a teacher, try to figure out why. Do you dislike the subject? Or do you like the subject but just can't warm up to the teacher?

If you don't like the subject being taught, it can affect your relationship with the teacher. Some students say it helps them to think of classes that seem like chores as stepping stones toward a bigger goal, like getting a diploma or going on to college. That allows them to keep the class in perspective. Other students say they try to find the practical value in classes they don't like. You may hate maths, but learning how to calculate averages and percentages can help you in everything from sports to leaving a tip.

If you find a subject hard, talk to your teacher or a parent about extra tutoring. If you find it boring, talk to your teacher (or another favourite teacher, friend, or parent) about ways to see the subject in a different light. Mat constantly fell asleep in his sophomore history class because the past seemed so removed from reality. But things changed when he mentioned his struggle over a project to his homeroom teacher. The teacher talked to Mat and found out that his great-grandfather had fought with the communist. The teacher suggested Mat uses his great-grandfather's letters in his project. Not only did Mat get an A, he also learned a lot about a family member he barely remembered from childhood.

What if you just don't like the teacher? When it comes to working with teachers, personality can come into play just as it can in any relationship. People naturally just get along better with some people than with others — it's impossible to like everyone all the time. Learning to work with people you don't connect with easily is a good skill to have in life, no matter what your goals are.

If you feel at odds with your teacher, pick your battles carefully. Questioning a grade or asking to retake a test once is fine. But second-guessing a teacher's judgment on your grades all the time may annoy him or her. Constantly squabbling over a few points on every test can cause friction in your relationship.

Common courtesy and respect are basic requirements of any relationship. Just as teachers need to be fair and treat everyone equally, students have responsibilities too. You don't have to like your teacher or agree with what he or she says, but it is necessary to be polite. If you need to be out of school for medical or other reasons, let your teacher know. And it's your responsibility to make up the work from missed classes. Don't expect your teacher to hunt you down or take class time to fill you in.

Just like personal problems can sometimes slow you down, the same is true for your teachers. Job stress, family issues, or health problems are all factors that can affect a teacher's performance, leaving him or her cranky, irritable, or unable to concentrate.

Keep in mind that too much disciplinary action can show up on a student's permanent record. This means that when someone asks for your school record, they can see the things you did — even if they happened years ago.

What to Do if You Don't Get Along

Before you try to get out of a class to escape a teacher you don't like, here are a few things you can try to make a difficult relationship work:

Meet with the teacher and try to communicate what you're feeling. Tell him or her what's on your mind, using statements such as, "It embarrasses me in class when I feel like my intelligence is being put down" or "I can't learn in class when I feel like only a few people ever get called on to participate." See if you can work it out between the two of you.

Ask yourself, "What can I learn from this teacher?" Even if you don't worship his or her personality or lectures, dig deep until you find a subject in which your teacher is very knowledgeable. Focus on that part of the teacher's personality, and use it as a tool for learning. Not only will you gain more knowledge in that subject, but a closer relationship with your teacher may help you understand one another better.

Talk to students who are doing well in the class and ask them for tips, tools, and a plan of action to get along with the teacher better. Sometimes having a second set of notes can be helpful, so asking a classmate who is willing to share them with you is a great idea. If you're too shy to talk to other students, study their actions and behaviour in the classroom and try to follow that lead.

If you still can't get along, make an appointment with the school counselor, who can offer many tips and suggestions for getting more out of difficult teacher relationships. Sometimes a counselor can act as a mediator between you and the teacher.

Teachers are there for more than just homework, and they know about more than just their subject matter. They can help you learn how to function as an adult and a lifelong learner. Undoubtedly, there will be a few teachers along the way who you'll always remember — and who might change your life forever.

Future World

People have always been intrigued of what the future will look like. The answers are quite simple and here you have them for the next 50 years.

How can we know what the future will look like?

To be able to understand the future, you must know the past. What has taken us to where we are today and what has changed along the way. The world has changed a lot in the last 150 years, but we humans are driven by the same basic needs as we were 150 years ago, food, sleep, sex, the feeling of being appreciated and loved. Will this change in the next 150 years? No.

What inventions have really made a difference in the last 150 years?

If you take away all gadgets that people in some part of the world are using for entertainment, the inventions that have affected most people around the world for everyday living are the telephone, electricity, radio, television, computer, the car and the ability to communicate through Internet. Then we of course have a lot of inventions that have made life easier, like new medicine, faster transports etc.

In general the inventions for the last 150 years have been a human strive for freedom and communication, to be able to get in control of the time and world. Since there is still much to do in this area, this will be the focus at least for the next 150 years.

But why do we need to predict the future?

Predicting the future is important for two reasons; first we need to start to think about what kind of future we would like for ourselves and to pass on to the next generation, and then we need to know what decisions we need to make today that will give the best result in the future.

Will we ever get those flying cars in the future that saw in pictures as kids?

Flying cars is an example of a scenario that has been pictured for the future for a long time. It is a great and exciting concept, but is it realistic? To start with we must find out if there’s a basic need for it, what are the pros and cons. Then we have to think about the system we have today, cars going on the ground, and the transition to a new system. To make it work in this example we need two parallel systems, with a road network for the flying cars simultaneousely as the common road network. Even if the flying cars are improved to be suitable for city traffic, the investments would be huge for a city to implement this, as well as for households to get that extra vehicle. So even if all the pros are there the practical steps for such a new route is too hard to overcome, so I’m sorry, there will be no road network for flying cars in the next 50 years.

How about the virtual worlds, do I need to go on vacation in the future or just have all the cells in my body experience an artificial vacation?

It might be possible in the future to experience the sand between your toes, feel the salt from the ocean on your lips, hear the waves and smell the seaweed, just lying in your bed at home. But we will not be able to fool the mind in the way that no matter how real the experience will feel, you will always know that it hasn’t happened for real. That will make all the difference. You can tell people today that you have seen the pyramids in Egypt because you have seen a picture of them, but you will never get the feeling of being there. So, even if a great invention is there for an affordable price, it will never replace the common experience if it is not genuine.

Please tell me we will get in contact with some aliens in the near future...

It is most likely that there are other life in the Universe considered there are billion solar systems. In the aspect that our solar system is about 4.6 billion years, other civilisations could be 10 million or even 1 billion years ahead of us. With these numbers in mind there is no greater chance that they will make contact with us within the next 50 years than in 100,000 years, and with the size of the Universe we will not likely be able to make any contact with them during this time.

So what will the future look like then?

What we will see in the next 50 years is the transition from an oil-dependent society, new medicine, the first steps in the development of artificial intelligence, continued exploration of space, more people to die from AIDS, hopefully a better state for the poor people in the world, challenges in the climate change, and new inventions that make life a little easier and entertaining for some.

How should I do then to make the future great?

Well, as you know the winner in life is not the one with the most money when he dies, the winner is the person who sleeps best at night. To feel good about yourself and the people around you, listen to them and show them the love and respect they deserve as fellow human beings and help those in need. That is what will matter when you go to bed at night in 50 years from now, and hopefully will give you a good night’s sleep.

Bad Habits Among Malaysian Drivers

Malaysians are a nice, kind and polite society. This is seemingly far fetch when they are on the road. But driving and motorcycling on the Malaysian road, I noticed their very bad habits and unusually rude driving.

Malaysian drivers seems different while they are on their feet. Unfortunately transformation takes place once they entered their car. Is driving on the Malaysian road puts that much of pressure into them until they resorted to impoliteness, rudeness and bullying other drivers?

Firstly, Malaysian drivers tend to cut the queue whenever its possible and felt no remorse in doing so. They just could not care if it affects other drivers' feelings. This is so wrong. This also make me to decide that they are ignorant.

Secondly, Malaysian drivers are rude when it comes to overtaking other drivers. They just seem too lazy to switch on their signals and cuts in abruptly without thinking of other people's safety. They just cut in too early and at times overtaking too near to the other driver. Didn't the driving school teaches them to overtake other drivers in a safer manner, did they?

Thirdly, Malaysian drivers who always felt the need to be faster than other drivers. They will honk you incessantly. These creatures are the worst lots of drivers and usually are on the highways. They will speed up more than 110 km/h and will start shooting the high lights from far away so to let you know that they are coming. Poor cars who are just overtaking are forced to go back into their path. Is this really necessary? They just couldn't wait to speed to their death, I presumed.

Fourthly, Malaysian drivers love to bully others while they are in another state. Especially drivers who return to their hometown.This is another rude creature that don't care of other drivers originated from other states. When they see a driver slows, they will honk. At traffic lights, they are worse! They will start honking at the front car. We all know when to accelerate. But are you in a hurry? So many times from what I've seen this drivers are not in a hurry. Once they are on the road after the traffic light, they drive very slow. So is the honking necessary in the first place? It's just plain rude and annoying.

Malaysian drivers are rude, I must say. I always wonder why Malaysian drivers cannot just have the courtesy and proper manners in their driving. Nice, kind and polite as projected is not seen on Malaysian road. I wonder is it the driving school fault which fails to cultivate good driving manners and courtesy? Or is it just because of our 'tidak apa' attitude?

Muscle Spasms and Cramps

If you've ever had muscle spasms or muscle cramps, you know they can be extremely painful. In some cases, a muscle may spasm so forcefully that it results in a bruise on the skin. Most muscle spasms and cramps are involuntary contractions of a muscle. A serious muscle spasm doesn't release on its own and requires manual stretching to help relax and lengthen the shortened muscle. Spasms and cramps can be mild or extremely painful. While they can happen to any skeletal muscle, they are most common in the legs and feet and muscles that cross two joints (the calf muscle, for example). Cramps can involve part of a muscle or all the muscles in a group. The most commonly affected muscle groups are:

   Back of lower leg / calf (gastrocnemius).

   Back of thigh (hamstrings).

   Front of thigh (quadriceps).

   Feet, hands, arms, abdomen

Muscle cramps range in intensity from a slight twitch or tic to severe pain. A cramped muscle can feel rock-hard and last a few seconds to several minutes or longer. It is not uncommon for cramps to ease up and then return several times before they go away entirely.

What Causes Muscle Cramps

The exact cause of muscle cramps is still unknown, but the theories most commonly cited include:

   Altered neuromuscular control

   Dehydration

   Electrolyte depletion

   Poor conditioning

   Muscle fatigue

   Doing a new activity

Other factors that have been associated with muscle cramps include exercising in extreme heat. The belief is that muscle cramps are more common during exercise in the heat because sweat contains fluids as well as electrolyte (salt, potassium, magnesium and calcium). When these nutrients fall to certain levels, the incidence of muscle spasms increases. Because athletes are more likely to get cramps in the preseason, near the end of (or the night after) intense or prolonged exercise, some feel that a lack of conditioning results in cramps

Treating Muscle Cramps

Cramps usually go away on their own without treatment, but these tips appears to help speed the healing process:

   Stop the activity that caused the cramp.

   Gently stretch and massage the cramping muscle.

   Hold the joint in a stretched position until the cramp stops.

Preventing Muscle Cramps

Until we learn the exact cause of muscle cramps, it will be difficult to say with any confidence how to prevent them. However, these tips are most recommended by experts and athletes alike:

   Improve fitness and avoid muscle fatigue

   Stretch regularly after exercise

   Warm up before exercise

Stretch the calf muscle: In a standing lunge with both feet pointed forward, straighten the rear leg.

Stretch the hamstring muscle: Sit with one leg folded in and the other straight out, foot upright and toes and ankle relaxed. Lean forward slightly, touch foot of straightened leg. (Repeat with opposite leg.)

Stretch the quadriceps muscle: While standing, hold top of foot with opposite hand and gently pull heel toward buttocks. (Repeat with opposite leg.)

Most muscle cramps are not serious. If your muscle cramps are severe, frequent, constant or of concern, see your doctor

Heart Disease

Atherosclerosis

Hardening of arteries

   Tunica intima thickens with deposits of Cholesterol, Fibrous (scar) tissue, Dead muscle cells, Blood platelets        

      Arteries become less elastic and partially narrowed

        ↑BP which in turn accelerates atherosclerosis

         Leads to endothelium damage and weak walls

Mechanism

   Excess cholesterol leaks from lipoproteins (LDLs)

   Deposited on arterial walls

   Macrophages (white blood cells) are trapped within cholesterol

   Release free radicals which damage the arterial wall

   Activates blood platelets which stick to damaged areas releasing clotting factors (thromboxanes)

   Forms a plaque which may rupture to produce a thrombus

   Circulating thrombus is called an embolus

   Embolus may lodge elsewhere in the circulation (brain, heart arteries)

   NB: healthy arteries produce anti-clotting factors (prostaglandins) → don't form clots

Factors that aggravate atheroma formation / atherosclerosis:

   Hypertension (↑BP)

   Smoking (release of free radicals)

   High LDL and low HDL

   NB: they all cause endothelial damage

Aneurysm

   Weak arterial walls may burst leading to severe loss of blood (haemorrhaging)

   Brain aneurysm is called a stroke

Deep Vein Thrombosis

   Clots are formed by

   Endothelial damage (see atherosclerosis)

   Altered blood components (dehydration, too many platelets)

   Altered blood flow (stasis of veins) → this is what causes DVT

      Prolonged immobility

      Such as paralysis, long-distance flights, lying down for weeks after surgery

   Thrombus often originates in calf veins

   Inflammation of vein walls → destroys vein valves

   Causes leg pain, swelling, and redness

   Elastic support stockings required for life

   Prevented by taking aspirin or warfarin which inhibit blood clotting

Coronary Heart Disease

   Atherosclerosis causes arteries to become narrowed

      More force required to move blood through narrowed vessels

      Blood pressure increases

   Stable angina

      ↑exercise leads to ↑oxygen requirements by heart

      Narrowed arteries prevent more blood to pass through

      Shortage of blood to heart muscle causes chest pain

      Cells do not die as some blood can still pass through

      Pain only occurs during activity but not at rest

Myocardial infarction (MI)

   Coronary artery is totally blocked by a thrombus/embolus

   No blood supply to heart muscle and cells die

   Irreversible if not treated within 90min

Heart failure

   Prolonged blockage of artery causes damage to heart muscle

   ↓contractions / ↓cardiac output / ↓pressure generated / less blood leaves heart

   More blood is stored:

       on the right side of the heart → enlarged heart

       in veins → swollen legs and enlarged liver

Lifestyle

Cholesterol

  Needed for

     Vitamin D production in skin

     Sex hormone production in gonads and adrenal glands

     Making cell membranes

     Produce bile acid (salts)

  Has properties similar to fats → soft, waxy, and insoluble (difficult to remove if deposits form)

  Transported in blood from liver to tissues

  Safe transport is needed due to its insolubility

  Achieved by lipoproteins, which are soluble fatty proteins

  These are wrapped around cholesterol

  Normally, only small amounts of free cholesterol escape

LDL

   Low density lipoproteins

  Carries cholesterol from liver to tissues

  Normally, some cholesterol 'leaks' from the lipoprotein and is absorbed to build cell membranes

   Excess LDL/cholesterol → too much cholesterol leaks out and causes atherosclerosis

HDL

   High density lipoprotein

   Picks up cholesterol from arterial walls and carries it away from tissues

   Travels to liver where cholesterol is removed with bile

Smoking

↓antitoxidants (vitamins), more damage due to release of free radicals by phagocytes

Nicotine constricts arteries causing platelets to stick together → vasoconstriction → heart must work harder to force blood through → increases BP

↑BP causes damage to blood vessel lining / endothelium / collagen

Leads to rise on blood platelets and makes them more sticky / form a plug / adhere to collagen fibres

Release of thromboplastin/thrombokinase

Fibrinogen converted to insoluble fibrin

Platelet plug trapped by fibrin mesh

Raises conc. of fibrinogen (in blood) → increased risk of clotting

↑LDL causes more cholesterol to leak out in blood

Carbon monoxide reduces the efficiency of the blood in terms of carrying oxygen

Haemoglobin combines with CO more readily than with oxygen → forms carboxyheamoglobin

Associated with plaque formation

Principle CHD = heart muscle receives inadequate amount of blood or oxygen/(coronary) blood supply reduced

Treatment

Medication

Beta blockers reduce heart rate and reduce oxygen required by heart

Aspirin prevents blood clotting and thrombosis formation

ACE inhibitors stabilize plaques → prevent thrombus to break off

Statins reduce LDL and increase HDL

Angioplasty

Deflated balloon-like device is passed up to the heart via the aorta

Guided into damaged coronary artery and inflated to stretch the artery

Heart by-pass graft

Leg veins and arteries from chest are used to by-pass the blocked region of the coronary artery

Involves open heart surgery

Reperfusion therapy after a myocardial infarction

Angioplasty done within 90 minutes of onset of chest pain

May prevent irreversible damage to the heart muscle

Prevention

1. Screen population for

   High BP

   High cholesterol

   Uncontrolled diabetes

   Smoking? Unhealthy diet? No exercises?

   Men over 55 and women over 65 are at highest risk

2. Monitor the behaviour of the heart during exercise

   Difficult but encouraging the population to adopt a more healthy lifestyle from an early age is important

   Often leads to changes in diet and weight management

3. Giving up smoking and reducing alcohol intake

    Reduces blood pressure

    Coronary heart disease is a long-term degenerative disease, starts at birth

Some misconceptions

Human body and health

Different tastes actually can be detected on all parts of the tongue by taste buds, with slightly increased sensitivities in different locations depending on the person, contrary to the popular belief that specific tastes only correspond to specific mapped sites on the tongue. The original tongue map was based on a mistranslation by a Harvard psychologist of a discredited German paper that was written in 1901.

There is no single theory that satisfactorily explains myopia—in particular, studies show that so-called eyestrain from close reading and computer games does not explain myopia. There is also no evidence that reading in dim light or sitting close to a television causes vision to deteriorate.

Shaving does not cause hair to grow back thicker or coarser or darker. This belief is due to the fact that hair that has never been cut has a tapered end, whereas, after cutting, there is no taper. Thus, it appears thicker, and feels coarser due to the sharper, unworn edges. Hair can also appear darker after it grows back because hair that has never been cut is often lighter due to sun exposure.

Hair and fingernails do not continue to grow after a person dies. Rather, the skin dries and shrinks away from the bases of hairs and nails, giving the appearance of growth.

Although there are hair care products which are marketed as being able to repair split ends and damaged hair, there is no such cure. A good conditioner might prevent damage from occurring in the first place, but the only way to get rid of split ends after they appear is by a hair cut.

Snapping or cracking one's knuckles does not cause arthritis.

Sugar does not cause hyperactivity in children. Double blind trials have shown no difference in behaviour between children given sugar full or sugar-free diets, even in studies specifically looking at children with attention-deficit/hyperactivity disorder or those considered "sensitive" to sugar. In fact, it was found that the difference in the children's behaviour was all in the parents' minds.

It is a common misconception that sleepwalkers should not be awakened. While it is true that a person may be confused or disoriented for a short time after awakening, it is actually quite dangerous not to wake a sleepwalker as they may injure themselves if they trip over objects or lose their balance while sleepwalking. Such injuries are common among sleepwalkers.

While the vitamin A in carrots does help to build healthy vision (among other things), it does not improve the eyesight of a person already in possession of healthy vision nor does it improve night vision. In fact, an excess of carrots can cause vitamin A toxicity and carotenemia in rare cases. This misconception arose from an RAF attempt to hide the discovery of radar from the Axis forces by claiming that their pilots had gained vastly improved night vision from being fed carrots, rather than from any technological advancement.

In Korea, it is commonly believed that sleeping in a closed room with an electric fan running can be fatal in the summer. According to the Korean government, "In some cases, a fan turned on too long can cause death from suffocation, hypothermia, or fire from overheating." The Korea Consumer Protection Board issued a consumer safety alert recommending that electric fans be set on timers, direction changed and doors left open. Belief in fan death is common even among knowledgeable medical professionals in Korea. According to Dr. Yeon Dong-su, dean of Kwandong University's medical school, "If it is completely sealed, then in the current of an electric fan, the temperature can drop low enough to cause a person to die of hypothermia."

High levels of testosterone do not necessarily make humans more aggressive and less cooperative, even though this is observed in other animals. Human behaviour is very complicated and heavily affected by social condition and beliefs.

Biology

Warts on human skin are caused by viruses that are unique to humans (Human papillomavirus). Humans cannot catch warts from toads or other animals; the bumps on a toad are not warts.

The claim that a duck's quack does not echo is false, although the echo may be difficult to hear for humans under some circumstances.

The notion that goldfish have a memory of only three seconds is false. They have been trained to navigate mazes and can recognize their owners after an exposure of a few months.

Lemmings do not engage in mass suicidal dives off cliffs when migrating. They will, however, occasionally, and unintentionally fall off cliffs when venturing into unknown territory, with no knowledge of the boundaries of the environment. The misconception is due largely to the Disney film White Wilderness, which shot many of the migration scenes (also staged by using multiple shots of different groups of lemmings) on a large, snow-covered turntable in a studio. Photographers later pushed the lemmings off a cliff.

Bats are not blind. While most bat species do use echolocation to augment their vision, all bats have eyes and are capable of sight.

It's a common myth that an earthworm becomes two worms when cut in half. This is not correct. An earthworm can survive being bisected, but only the front half of the worm (where the mouth is located) can survive, while the other half dies. On the other hand, species of the planaria family of flatworms actually do become two new planaria when bisected or split down the middle.

Jaundice in Newborns

Jaundice refers to the yellow colour of the skin and whites of the eyes caused by excess bilirubin in the blood. Bilirubin is produced by the normal breakdown of red blood cells.

Normally, bilirubin passes through the liver and is excreted as bile through the intestines. Jaundice occurs when bilirubin builds up faster than a newborn's liver can break it down and pass it from the body. Reasons for this include:

  Newborns make more bilirubin than adults do since they have more turnover of red blood cells.

  A newborn baby's still-developing liver may not yet be able to remove adequate bilirubin from the blood.

  Too large an amount of bilirubin is reabsorbed from the intestines before the baby gets rid of it in the stool.

High levels of bilirubin — usually above 25 mg — can cause deafness, cerebral palsy, or other forms of brain damage in some babies. In less common cases, jaundice may indicate the presence of another condition, such as an infection or a thyroid problem. The American Academy of Pediatrics (AAP) recommends that all infants should be examined for jaundice within a few days of birth.

Types of Jaundice

The most common types of jaundice are:

Physiological (normal) jaundice: occurring in most newborns, this mild jaundice is due to the immaturity of the baby's liver, which leads to a slow processing of bilirubin. It generally appears at 2 to 4 days of age and disappears by 1 to 2 weeks of age.

Jaundice of prematurity: occurs frequently in premature babies since they are even less ready to excrete bilirubin effectively. Jaundice in premature babies needs to be treated at a lower bilirubin level than in full term babies in order to avoid complications.

Breastfeeding jaundice: jaundice can occur when a breastfeeding baby is not getting enough breast milk because of difficulty with breastfeeding or because the mother's milk isn’t in yet. This is not caused by a problem with the breast milk itself, but by the baby not getting enough to drink.

Breast milk jaundice: in 1% to 2% of breastfed babies, jaundice may be caused by substances produced in their mother's breast milk that can cause the bilirubin level to rise. These can prevent the excretion of bilirubin through the intestines. It starts after the first 3 to 5 days and slowly improves over 3 to 12 weeks.

Treatments

In mild or moderate levels of jaundice, by 1 to 2 weeks of age the baby will take care of the excess bilirubin on its own. For high levels of jaundice, phototherapy — treatment with a special light that helps rid the body of the bilirubin by altering it or making it easier for your baby's liver to get rid of it — may be used.

More frequent feedings of breast milk or supplementing with formula to help infants pass the bilirubin in their stools may also be recommended. In rare cases, a blood exchange may be required to give a baby fresh blood and remove the bilirubin.

If your baby develops jaundice that seems to be from breast milk, your doctor may ask you to temporarily stop breastfeeding. During this time, you can pump your breasts so you can keep producing breast milk and you can start nursing again once the condition has cleared.

If the amount of bilirubin is high, your baby may be readmitted to the hospital for treatment. Once the bilirubin level drops and the treatment is stopped, it is unlikely that treatment for jaundice will need to be restarted.

Blood group incompatibility (Rh or ABO problems): if a baby has a different blood type than the mother, the mother might produce antibodies that destroy the infant's red blood cells. This creates a sudden buildup of bilirubin in the baby's blood. Incompatibility jaundice can begin as early as the first day of life. Rh problems once caused the most severe form of jaundice, but now can be prevented with an injection of Rh immune globulin to the mother within 72 hours after delivery, which prevents her from forming antibodies that might endanger any subsequent babies.

Symptoms and Diagnosis

Jaundice usually appears around the second or third day of life. It begins at the head and progresses downward. A jaundiced baby's skin will usually appear yellow first on the face, followed by the chest and stomach, and finally, the legs. It can also cause the whites of an infant's eyes to appear yellow.

Since many babies are now released from the hospital at 1 or 2 days of life, it is best for the baby to be seen by a doctor within 1 to 2 days of leaving the hospital to check for jaundice. Parents should also keep an eye on their infants to detect jaundice.

If you notice your baby’s skin or eyes looking yellow you should contact your child's doctor to see if significant jaundice is present.

At the doctor's office, a small sample of your infant's blood can be tested to measure the bilirubin level. Some offices use a light meter to get an approximate measurement, and then if it is high, check a blood sample. The seriousness of the jaundice will vary based on how many hours old your child is and the presence of other medical conditions.

Tenis MSKPPM 2009 di Kota Kinabalu (19th - 23rd Dec)

Tahniah untuk Team Tenis PSKPP Kedah for the 3rd place.
The whole Malaysia babe...

PMR Result 2009

How to Beat Four Major Types of Tennis Player

No two tennis players have exactly the same game, but most of the opponents you're likely to face can be placed into one of several major categories. Learning to adapt your strategy to a wide variety of opponents is one of the keys to becoming a tough competitor. If you succeed at becoming this adaptable, you'll enter an elite minority -- those players who can be any one of the major player types as the situation demands.

The Dinker, a.k.a. Pusher, a.k.a. Human Backboard: The dinker almost never hits hard, but gets everything back. "Dinker" is a somewhat misleading name, because one would normally think of a dink shot as something short and soft. The best among this breed can keep most shots deep, lob effectively, and aim fairly well. Dinkers drive a lot of opponents crazy, because they win by getting you to make all of the mistakes. (It's a lot more frustrating to make a mistake than to have an opponent hit a brilliant shot that no one could have got.)

Winning Strategy:

1. Attack at the net. Even the quickest players, who can run down almost anything you hit from your baseline, won't be able to run down an aggressive volley or overhead. Tennis is largely a matter of time, and by being at net, you cut in half both the time between your opponent's hit and yours and the time he has to react to your shot.
2. Get him to cough up a short ball. This might not be easy, but experiment. One tactic very likely to work is making the ball bounce above his shoulders on the backhand side. Most players can't hit deep off these shots effectively.
3. Be patient. He can't hurt you with his shots, so wait for the right ball before going for a winner or attempting an approach shot.
4. Pull him to net with a drop shot or good, low short ball. If he's not much good at hitting an aggressive response, you'll have an easy opportunity to pass him.

The Moon-Baller: Once a major contingent on the pro tours, especially on the women's side, the moon-baller is like a more skilled and specialized human backboard. She won't hit hard, but she will hit high, deep, and with strong topspin. If you're not used to this kind of shot, it can be tough to handle, and she can keep hitting them all day long.

Winning Strategy:

1. Attack at net, but be ready to hit a lot of overheads and to chase a lot of balls back toward your baseline. You'll need to come in on a better approach shot than you would against an ordinary dinker.
2. Try some sneak volleys. Start trading moonballs back and forth, then, when you've hit a nice deep, high one, sneak in toward the net and take the next ball in the air. It's hard for your opponent to see what you're doing while watching a deep, high ball, so she might not see you until you're about to pound the smash or swinging topspin volley.
3. Learn to hit on the rise. Moonballs are toughest if you let them bounce way above your comfort zone. By hitting them on the rise, you'll take them at a more comfortable height, your ball will come back at your opponent earlier, and the ball will bounce off your strings harder, giving your shot more power with less effort. The timing required to do this is tough, though.
4. Pull her to net. She won't be able to hit a moon ball off your drop shot or low, short ball, so she'll probably feed you an approach shot you can handle with ease.

The Power Baseliner: This is the most common type on the pro tour today. As opposed to an all-court player, the power baseliner would much rather go for winners from near his baseline than at the net.

Winning Strategy:

1. Keep your shots deep. If you give a power hitter a short ball, you'll have less time to react to his shot, and he'll be able to create sharper angles.
2. Try to keep the ball out of his "wheelhouse," the height at which he can most comfortably hit the ball. Either slice the ball so that it skids quite low or use a fairly high topspin that kicks up above his shoulders.
3. Make him hit a lot of balls. Keep running his shots down, because a hard hitter doesn't have much margin for error, and he'll eventually miss one.
4. Pull him up to net with good drop shots or low, skidding slices. This is a risky play, because if your short ball sits up at all, he'll put it away. If you hit a good short ball though, you'll force him to try to play the net, and a lot of power baseliners don't volley well.
5. Mix up the speeds and spins on your shots. A power hitter needs good timing, and the more variety you throw at him, the more difficult his timing will be.
6. See what happens if you attack at net. A lot of baseliners aren't used to hitting passing shots and make errors such as hitting the net by aiming too low.

The Serve-and-Volleyer: A good serve-and-volleyer has a big advantage: rarity. Even among the pros, this is a diminishing breed. At the typical club, only a handful of advanced players serve-and-volley. A true serve-and-volley player will come in behind virtually every first serve and most second serves, and when you're serving, she'll often try to come in behind either her return of serve or another approach shot early in the point.

Winning Strategy:

1. Concentrate on aim. Don't look at the incoming opponent or at where you want the ball to go. Keep looking at the ball while you aim either down the line, at the corner of the service box crosscourt, into her body, at her feet, or lobbed over her head.
2. Use topspin to make your returns drop in. Topspin allows you to hit harder at a given height without hitting long. It will also make your sharply angled crosscourt passes drop before they go wide or make the ball dive down at the feet of the incoming opponent.
3. Try some low chip returns at the server's feet.
4. Step in on the return to take the ball early. This will get the ball back sooner, giving the server less time to set up for a volley.
5. If your opponent is coming in behind her returns, too, try some serve-and-volley yourself. Take the net away from her by getting there first.

Winning Tips (Singles)

At any level of tennis competition, you'll fare best if you focus on having fun and improving your game, not on whether you win. Part of improving is learning how to win, but you should be happier about losing a match in which you played well against a better opponent than winning a match in which you played poorly.

The essence of your strategy early in your tennis development should be to win with consistency. At every level below advanced, players miss the vast majority of attempts at hitting a winner. If you get lots of balls back, giving an opponent more chances to make a mistake, he'll usually make that mistake and hand you the point. Most players run out of patience after a certain number of shots within a point. The more patient player has the advantage.

At the more advanced levels, a strategy centered on consistency requires good foot speed, but at the beginner level, your opponents won't get many hard shots in, so the balls you actually need to chase will usually be moving pretty slowly. You can win with consistency well into the intermediate level even if speed isn't one of your strengths. Approaching the advanced level, a slower player has to learn a more aggressive style, but we'll address that when we get there.

For beginners through early intermediates, here are five key tips for winning matches:

1. Hit groundstrokes high to hit deep. Unless you hit hard, aiming your forehands and backhands between three and eight feet above the net will almost guarantee that you'll get the ball in, and it will also help you keep the ball deep. Very deep balls can often draw an error from an inexperienced opponent, and depth in general will limit your opponent's options. You'll want to hit some short balls on purpose, but your standard shot should be deep.
2. Hit second serves high to hit deep. Aim your second serves two to five feet above the net for reliability and depth. The pros do this too, but they use heavy topspin that allows them to add quite a bit more pace than you'll be able to. If you know you have a reliable second serve, you can experiment more with an aggressive first serve and probably earn a few easy points. Until you start learning to spin your first serve, not too many hard ones will go in, but experimenting will help you judge how much speed to attempt.
3. Pull your opponent forward, then hit past her. This is one of the easiest and most reliable tactics you can use. Hitting a short ball to an advanced player is extremely dangerous, because she'll usually reply with a winner, but beginners will most often just hit the ball right back to you. Beginners get caught in "No Person's (formerly No Man's) Land," the area between the baseline and service line, all the time. When you see your opponent there, just aim the ball to either side of her and several feet deeper than she is standing, and you'll almost certainly win the point.
4. Recover your court position quickly. This is your defense against tip #3 and a lot of other difficult situations. Unless you're attacking at the net, which isn't easy as a beginner, you should get back to a spot somewhat diagonally opposite your opponent and roughly three feet behind your baseline after each ball you hit.
5. Use full swings. Full swings don't have to be fast swings. It's tempting to poke at the ball as a way to keep from hitting too hard, but you'll find that a longer swing is far more reliable, and it will be much better for your arm and your rate of improvement. If you want to take some speed off your shot, just slow down your full swing.

Final Exam Result 2009

Students can check their final exam result (online) through our school website.
Check it out

Top Five Mistakes of Inexperienced Tennis Players

1. Poking at the ball due to over-caution: It's surprising how many players have two sets of strokes: their long, fluid, practice strokes and their short, choppy, match strokes. When these players get into matches, they become so over-cautious, they're afraid to take a real swing at the ball. They just poke at the ball, as if enough gentleness will coax it into behaving properly.

Of course, you learn long strokes not because they look pretty, but because they work better. When you poke at the ball, your racquet is in the process of decelerating when it meets the ball. This makes it unstable, and the result is an unpredictable racquet angle that can send the ball all over the place.

In addition, short, pokey strokes generally don't produce any topspin, which is the best tool for consistency, and they don't generate any pace. Failing to generate good offense is a great risk in itself, because you prolong points you should have already won. You'll have no offense with pokey strokes.

2. Getting caught in "No Person's Land": When you move inside your baseline to get a ball, you have to either get back behind your baseline or move to the net right away. From inside the area between the baseline and the service line, you can't volley effectively, and any ball that lands behind you won't be playable with a groundstroke. If you're good at the net, move forward whenever you can hit a strong approach shot. If not, learn to backpedal quickly, but still go to net if you don't have time to get all the way back before it's time to hit the next ball. You don't want to get caught retreating when the ball

3. Hitting to your opponent: At every level of tennis, the easiest direction in which to hit the ball is the direction from which it came. This is one of the main reasons players tend to hit back to their opponents. We also tend to hit toward whatever we're most focused upon. By far the most conspicuous thing on the other side of the net is your opponent, so your attention, and thus your shot, tends to be drawn in that direction. To overcome this, try to focus your eyes on the ball while visualizing target zones on the court.

4. Not attacking dinky serves: Against many opponents, the easiest balls coming your way will be second serves. Inexperienced players hit truly dinky second serves that are just begging to be attacked. You can hit them hard and deep, at a sharp angle, or very short (drop shot). If you keep punishing these dinky serves, your opponent will probably start trying to hit a better one than he can, and his resulting double faults will drive him nuts. Frustration will increase his errors, giving you lots of bonus points.

5. Admiring your shot: Yes, hitting a good shot is central to tennis, but you can't rest on your laurels--at least, not right away. If you stand there watching the beautiful flight of your shot, you'll be way out of position when that beauty comes back. Generally, you need to start moving immediately back toward the middle of the range of angles your opponent could hit next. This position is somewhat diagonally opposite your opponent if you're at your baseline, and it's somewhat toward the ball if you're at the net.

Credit to Jeff Cooper

5 Great Shot Combinations

One of the marks of an experienced tennis competitor is thinking beyond the shot you are about to hit. Your odds of hitting a winner are far greater if you set yourself up for it than if you try to create it spontaneously out of sheer shot-making brilliance.

Here are five shot combinations that work especially well:

1. Hit short enough to force your opponent to move ten or more feet forward into her court. When she fails to get back behind her baseline, which most players at this level often do, simply hit the next ball deeper than her position and at least eight feet to either side of her. As long as your opponent isn't good at putting away short balls, this is a fairly safe tactic, and it can yield a ton of points. Keeping your short ball low will make it even safer--harder to put away.

2. Hit a high, deep topspin, preferably to your opponent's backhand side, that will kick above her shoulders. Most players can't generate much pace on a ball above their shoulders on the backhand side, so you'll usually get a high, floating ball that's easy to put away at the net. When your shot kicks especially high, your opponent will be looking up and to the side as she hits the ball, so she often won't see you moving in to volley. With this "sneak volley," you can catch your opponent sending what would have been a fairly safe shot (if you had stayed back) but is, instead, a perfect setup for your volley.

3. Hit to your opponent's "side pocket," the outside corner of the service box, then put the next ball away to the opposite side or, as your opponent hurries back toward the center of the court, hit behind him (wrong-footing him). This is a classic shot combination that can be started with a slice serve, a sharp crosscourt topspin groundstroke, or a delicately angled slice groundstroke, usually a backhand. One hazard though: if your opponent gets to your widely angled shot in time to set up a good reply, he'll be able to create an even sharper angle than you did, because of his wide position on the court.

4. The drop-shot-then-lob combination is always fun, but it takes considerable finesse to execute safely. If your drop shot is too deep or your lob too short, most opponents will easily take the point, but you'll find some otherwise solid players who have a lot more trouble putting away short balls and/or overheads than they should. When you practice drop shots, try to get them to bounce at least three times inside the service line of your opponent's court. A good lob should land no more than four feet from your opponent's baseline, and against some taller opponents, your margin might shrink to less than three feet.

5. If you want to try a combination shot your opponent might not have seen often or at all, the sidespin backhand approach shot should be fun. Hit a backhand combination of sidespin and backspin as you start toward the net. Usually, your opponent won't be able to resist trying to see what you're doing as you're coming in. With some of his attention diverted from the ball, he won't be quite ready for its sideways skid, and he'll hit off center if at all, giving you either an easy volley or no need to volley.

Five Mental Toughness Tips (For Tennis Players)

Most tennis players are all too familiar with the difficulty of the mental half of tennis competition. The power of the mind is evident at every level, from Roger Federe or Rafael Nadal at Wimbledon to an eight-year-old afraid to use any of her full strokes in her first tournament. Tennis is a gold mine for sports psychologists, and some players spend several hours each week just doing mental toughness exercises.

Here are five simple techniques you can try right away:

1. The best all-around mental repair tool is the simple phrase, "only the ball." It cures, at least temporarily, most of the big pitfalls. Whether you're upset, angry, nervous, or just distracted, repeat this phrase to block out negative thoughts and return your focus to where it belongs, the ball.

2. Probably the hardest time to concentrate is when you're getting ready to return serve. Your opponent has the ball, so your mind seems to sense that this is an opportunity for a little time off. The next thing you know, your musings about which movie to watch tonight are rudely interrupted by a chunk of rubber and fuzz coming in at 90 m.p.h. A combination of three devices can help keep your mind on the job:

While your opponent is preparing, try to focus on something undistracting, like your strings. (Strings get readjusted a lot more than needed because of this little trick.)

As she tosses the ball, try to watch it come out of her hand and say to yourself a long, drawn-out, "baaalll."

As she hits the serve, say "hit," followed by "bounce," then on your return swing, "hit."

The "baaalll" device seems to work well for most players without much of a downside. The "hit, bounce, hit" phrase is also popular, but for some players it distracts more than it helps.

3. It's possible to become too analytical in the middle of a match, which will keep you from letting your strokes take their natural flow, but you don't want to shut down your analytical abilities, either. If you miss a shot you shouldn't have, you'll dwell on it less if you take a moment to figure out what you did wrong, then say to yourself, "Okay, I won't do that again." It's usually a good idea to repeat the stroke right away with the correct motion. You might very well make the same error the next time the stroke comes up, but just go ahead and apply the same process. Eventually you will get it right, and in the meantime, a little extra optimism won't hurt.

4. Learn versatility. If you have only one playing style, and it's not working, your lack of strategic options also creates a shortage of mental safety valves. A key factor in psychological health in general is feeling empowered to choose different courses of action. If you have a Plan B, C, and D on the tennis court, the failure of Plan A is unlikely to cause despair. Tennis players often lose because at least a part of them secretly gives up. You won't give up while you have something else to try. Learn to play every part of the court and hit every kind of shot with every kind of spin. You'll likely uncover a weakness in a seemingly invicible opponent. Variety makes the game more creative and interesting, too.

5. Look alert, energetic, confident, and happy. Looking so will actually help you be so to a significant extent, and it will keep you from giving encouragement to your opponent. If your opponent is at all prone to choking, your look of ready confidence on the verge of seeming defeat might keep just enough doubt in her mind to make her cave under the pressure of closing out the match.

Good luck.

Nikolay Davydenko-Juan Martin Del Porto ATP Final Match Analysis

Nikolay Davydenko won his first ATP Finals Championship by beating Juan Martin Del Potro 6-3, 6-4. Davydenko was clearly the more aggressive player and possibly even fresher than Del Potro.

Here are some of the key points of the first set:

1. Davydenko started extremely focused as he didn’t commit an unforced error until the 6th game and still managed to hit 7 winners from the baseline in that period of time.

2. Del Potro on the other hand saved himself twice mostly with first serve winners as 7 of the 8 points needed to win his first two service games came from his service winners. Had Del Potro not served that well, the first set would be over in 20 minutes for Davydenko.

3. Davydenko had one lapse of concentration at 4-2 up where he committed 2 unforced errors and a double fault but stayed aggressive and saved the game with 2 service and 3 forehand winners.

4. Davydenko in the end made 23 points through winners and forcing shots and gave only 6 points to Del Potro through unforced errors. That’s a +17 margin. Del Potro’s first set margin was +5.

5. The stats also showed that Davydenko played 40% of the shots inside the baseline in the first set and Del Potro only 20%.

Second set

1. Del Potro started the second set more aggressively and more focused as he made 7 winners and only 1 unforced error in the first three games but Nikolay was strong enough to hold his serve.

2. Davydenko’s level of play dropped just once in the second set at 2-3 when he made 4 unforced errors but Del Potro was just not aggressive enough since the stats show that Davydenko also made 4 winners / forcing shots in that same game.

3. Davydenko played a perfect game at 4-4 where he broke Del Potro’s serve on 0 by hitting 3 forehand and 1 backhand winner. There were no unforced errors from Del Potro but Juan Martin definitely played too slow and allowed Davydenko to dominate the rallies.

4. Davydenko’s margin in the second set was +13 and Del Potro’s +7. This tells us that Del Potro still played reasonably well as he made more winners than unforced errors but his game was slightly too passive and that allowed Davydenko to control the rallies.

In summary, this was one the best tennis performances by Davydenko that we have ever seen him play and he really deserved to win the tournament.

Juan Martin Del Potro was just “flat” after a tiring semi-final match with Soderling and was just unable to produce the same high level play so quickly after that match.

Credit to tennis thoughts

Dear all my students...

When you were in school, you couldn't wait to be out of it. Now that you're leaving school soon, you will miss all your friends and even your teachers.

When you're young, you don't appreciate a lot of things because you're busy having fun. Only when you're older do you get wiser and wish that you had spent more time doing things right the first time round. But everyone has to go through this order to understand that life is not perfect, but it is still your life, so make full use of it......

Quick Revision

Nucleus - contains DNA

Nucleolus - in nucleus, manufactures ribosomes

Endoplasmic reticulum - move materials from one part of the cell to another

Golgi apparatus - where proteins are converted to their final form

Lysosomes - contain digestive enzymes

Chloroplasts - contain pigments important to photosynthesis

Mitochondria - site of ATP production

Ribosomes - manufacture of proteins

Centrioles and microtubules - support, cell locomotion, forming spindle in nuclear division

Cell wall - support, prevents cell from bursting by taking in too much water

Osmosis: the net movement of water molecules through a partially permeable membrane from an area of higher water potential to an an area of lower water potential.

Facilitated diffusion: This is where polar molecules are transported across membranes. Molecules bind with transport proteins which change shape and move the molecules across the membrane. No metabolic energy is required.

Examples of active transport: the calcium pump (skeletal muscles), the sodium-potassium pump (nerve cells).

Endocytosis: An active process whereby substances are taken into the cell by infoldings of the surface membrane. (Exocytosis is similar.)

Mitosis: Mitosis is a type of cell division where the daughter cells have the same number of chromosomes as the parent cell and are genetically identical to the parent cell. Mitosis takes place in four stages: prophase, metaphase, anaphase and telophase.

During prophase, each chromosome forms two chromatids joined by a centromere. Two centrioles begin to move forming a spindle and the nuclear envelope breaks down.

During metaphase, the chromosomes are attached to the spindle fibres and line up at the equator of the cell.

During anaphase, the centromeres split and the chromatids are pulled to opposite poles of the cell.

During telophase, the nuclear envelope reforms and the cell membrane narrows at the middle, forming two daughter cells

 

Sucrose = glucose + fructose; main form in which carbohydrate is transported in plants

Maltose = 2 glucose; found in some germinating seeds eg barley
Lactose = glucose + galactose; found in milk

Lipids - insoluble in water, soluble in organic solvents

Fats & oils - compounds of glycerol and fatty acids

Structure of proteins
Primary - Order of the amino acids
Secondary - The way the chain folds/turns on itself due to hydrogen bonding
Tertiary - Cross-links including hydrogen bonds, inonic bonds and sulphur bridges
Quaternary - The arrangement of two or more polypeptides eg haemoglobin
Collagen - fibrous protein; great tensile strength; found in bones, tendons, skin etc; structure = triple helix
Insulin - globular protein, folded chain held together by 2 disulphide bridges with the loop removed

Gene Idea

Alleles, alternative versions of a gene. A somatic cell has two copies of each chromosome (forming a homologous pair) and thus two alleles of each gene, which may be identical or different. This figure depicts an F1 pea hybrid with an allele for purple flowers, inherited from one parent, and an allele for white flowers, inherited from the other parent.

Mendel’s law of segregation. This diagram shows the genetic makeup of the generations in Figure 14.3. It illustrates Mendel’s model for inheritance of the alleles of a single gene. Each plant has two alleles for the gene controlling flower colour, one allele inherited from each parent. To construct a Punnett square, list all the possible female gametes along one side of the square and all the possible male gametes along an adjacent side. The boxes represent the offspring resulting from all the possible unions of male and female gametes.

Phenotype versus genotype. Grouping F2 offspring from a cross for flower color according to phenotype results in the typical 3:1 phenotypic ratio. In terms of genotype, however, there are actually two categories of purple–flowered plants, PP (homozygous) and Pp (heterozygous), giving a 1:2:1 genotypic ratio.

Pedigree Analysis

Unable to manipulate the mating patterns of people, geneticists must analyze the results of matings that have already occurred. They do so by collecting information about a family’s history for a particular trait and assembling this information into a family tree describing the interrelationships of parents and children across the generations—the family pedigree shows a three–generation pedigree that traces the occurrence of a pointed contour of the hairline on the forehead. This trait, called a widow’s peak, is due to a dominant allele, W. Because the widow’s–peak allele is dominant, all individuals who lack a widow’s peak must be homozygous recessive (ww ). The two grandparents with widow’s peaks must have the Ww genotype, since some of their offspring are homozygous recessive. The offspring in the second generation who do have widow’s peaks must also be heterozygous, because they are the products of Ww × ww matings. The third generation in this pedigree consists of two sisters. The one who has a widow’s peak could be either homozygous (WW ) or heterozygous (Ww ), given what we know about the genotypes of her parents (both Ww).

Cystic Fibrosis

The most common lethal genetic disease in the United States is cystic fibrosis, which strikes one out of every 2,500 people of European descent but is much rarer in other groups. Among people of European descent, one out of 25 (4%) is a carrier of the cystic fibrosis allele. The normal allele for this gene codes for a membrane protein that functions in chloride ion transport between certain cells and the extracellular fluid. These chloride transport channels are defective or absent in the plasma membranes of children who inherit two recessive alleles for cystic fibrosis. The result is an abnormally high concentration of extracellular chloride, which causes the mucus that coats certain cells to become thicker and stickier than normal. The mucus builds up in the pancreas, lungs, digestive tract, and other organs, leading to multiple (pleiotropic) effects, including poor absorption of nutrients from the intestines, chronic bronchitis, foul stools, and recurrent bacterial infections. Recent research indicates that the extracellular chloride also contributes to infection by disabling a natural antibiotic made by some body cells. When immune cells come to the rescue, their remains add to the mucus, creating a vicious cycle.

If untreated, most children with cystic fibrosis die before their fifth birthday. Gentle pounding on the chest to clear mucus from clogged airways, daily doses of antibiotics to prevent infection, and other preventive treatments can prolong life. In the United States, more than half of the people with cystic fibrosis now survive into their late 20s or even 30s and beyond.

Sickle–Cell Disease

The most common inherited disorder among people of African descent is sickle–cell disease, which affects one out of 400 African–Americans. Sickle–cell disease is caused by the substitution of a single amino acid in the hemoglobin protein of red blood cells. When the oxygen content of an affected individual’s blood is low (at high altitudes or under physical stress, for instance), the sickle–cell hemoglobin molecules aggregate into long rods that deform the red cells into a sickle shape (see Figure 5.21). Sickled cells may clump and clog small blood vessels, often leading to other symptoms throughout the body, including physical weakness, pain, organ damage, and even paralysis. The multiple effects of a double dose of the sickle–cell allele are another example of pleiotropy. Regular blood transfusions can ward off brain damage in children with sickle–cell disease, and new drugs can help prevent or treat other problems, but there is no cure.

Although two sickle–cell alleles are necessary for an individual to manifest full–blown sickle–cell disease, the presence of one sickle–cell allele can affect the phenotype. Thus, at the organismal level, the normal allele is incompletely dominant to the sickle–cell allele. Heterozygotes, said to have sickle–cell trait, are usually healthy, but they may suffer some sickle–cell symptoms during prolonged periods of reduced blood oxygen. At the molecular level, the two alleles are codominant; both normal and abnormal (sickle–cell) hemoglobins are made in heterozygotes.

About one out of ten African–Americans has sickle–cell trait, an unusually high frequency of heterozygotes for an allele with severe detrimental effects in homozygotes. One explanation for this is that a single copy of the sickle–cell allele reduces the frequency and severity of malaria attacks, especially among young children. The malaria parasite spends part of its life cycle in red blood cells (see Figure 28.11), and the presence of even heterozygous amounts of sickle–cell hemoglobin results in lower parasite densities and hence reduced malaria symptoms. Thus, in tropical Africa where infection with the malaria parasite is common, the sickle–cell allele is both boon and bane. The relatively high frequency of African–Americans with sickle–cell trait is a vestige of their African roots.

Mating of Close Relatives

When a disease–causing recessive allele is rare, it is relatively unlikely that two carriers of the same harmful allele will meet and mate. However, if the man and woman are close relatives (for example, siblings or first cousins), the probability of passing on recessive traits increases greatly. These are called consanguineous (“same blood”) matings, and they are indicated in pedigrees by double lines. Because people with recent common ancestors are more likely to carry the same recessive alleles than are unrelated people, it is more likely that a mating of close relatives will produce offspring homozygous for recessive traits—including harmful ones. Such effects can be observed in many types of domesticated and zoo animals that have become inbred.

There is debate among geneticists about the extent to which human consanguinity increases the risk of inherited diseases. Many deleterious alleles have such severe effects that a homozygous embryo spontaneously aborts long before birth. Still, most societies and cultures have laws or taboos forbidding marriages between close relatives. These rules may have evolved out of empirical observation that in most populations, stillbirths and birth defects are more common when parents are closely related. Social and economic factors have also influenced the development of customs and laws against consanguineous marriages.

Dominantly Inherited Disorders

Although many harmful alleles are recessive, a number of human disorders are due to dominant alleles. One example is achondroplasia, a form of dwarfism with a prevalence of one among every 25,000 people. Heterozygous individuals have the dwarf phenotype

Therefore, all people who are not achondroplastic dwarfs—99.99% of the population—are homozygous for the recessive allele. Like the presence of extra fingers or toes mentioned earlier, achondroplasia is a trait for which the recessive allele is much more prevalent than the corresponding dominant allele.

Dominant alleles that cause a lethal disease are much less common than recessive alleles that do so. All such lethal alleles arise by mutations (changes to the DNA) in a sperm or egg; presumably, such mutations occur equally often whether the mutant allele is dominant or recessive. However, if a lethal dominant allele causes the death of offspring before they mature and can reproduce, the allele will not be passed on to future generations. In contrast, a lethal recessive allele can be perpetuated from generation to generation by heterozygous carriers who have normal phenotypes. These carriers can reproduce and pass on the recessive allele. Only homozygous recessive offspring will have the lethal disease.

A lethal dominant allele can escape elimination if it causes death only at a relatively advanced age. By the time the symptoms become evident, the individual may have already transmitted the lethal allele to his or her children. For example, Huntington’s disease , a degenerative disease of the nervous system, is caused by a lethal dominant allele that has no obvious phenotypic effect until the individual is about 35 to 45 years old. Once the deterioration of the nervous system begins, it is irreversible and inevitably fatal. Any child born to a parent who has the allele for Huntington’s disease has a 50% chance of inheriting the allele and the disorder. (The mating can be symbolized as Aa × aa, with A being the dominant allele that causes Huntington’s disease.) In the United States, this devastating disease afflicts about one in 10,000 people.

Until relatively recently, the onset of symptoms was the only way to know if a person had inherited the Huntington’s allele. This is no longer the case. By analyzing DNA samples from a large family with a high incidence of the disorder, geneticists tracked the Huntington’s allele to a locus near the tip of chromosome 4.

Meiotic nondisjunction. Gametes with an abnormal chromosome number can arise by nondisjunction in either meiosis I or meiosis II.

Alterations of chromosome structure. Vertical arrows indicate breakage points. Dark purple highlights the chromosomal parts affected by the rearrangements.

Down syndrome.The child exhibits the facial features characteristic of Down syndrome. The karyotype shows trisomy 21, the most common cause of this disorder.