Thursday, September 29, 2011

Milky Way : Galactic Quadrant


The Milky Way is the galaxy that contains the Solar System.  It is a barred spiral galaxy containing 200-400 billion stars, with 100,000 light years in diameter, and 1,000 light years thick.  It is estimated to be about 13.2 billion years old, nearly as old as the Universe.

Edwin Hubble, in 1920s observed that the Milky Way is just one of around 200 billion galaxies in the observable universe.



Galactic Quadrant

A galactic quadrant refers to one of four circular sectors in the division of the Milky Way galaxy.

Ancient Mesopotamian formulae spoke of “the four corners of the universe” & ”the heaven’s four corners”;
Biblical Book of Jeremiah echoes this phraseology : “And upon Elam will I bring the four winds from the four quarters of heaven” ( Jeremiah 49:36 )

Galactic quadrants within fictional Star Trek are based around a meridian that runs from the center of the galaxy through Earth’s solar system. 


                                                


Real world :  
Sun as center                                       

Described using ordinals, as               
1st galactic quadrant                              
2nd galactic quadrant                         
3rd galactic quadrant                          
4th galactic quadrant                         



Star Trek :
Galactic Core as center

Designated by Greek letters, as
Gamma Quadrant   
Alpha Quadrant
Beta Quadrant
Delta Quadrant



Tuesday, September 20, 2011

Motion Sickness

Motion sickness or kinetosis, also known as travel sickness, is a condition in which a disagreement between visually perceived movement and the vestibular system’s sense of movement.  Depending on the cause it can also be referred to as seasickness, car sickness, airsickness, or simulation sickness.

Sopite syndrome is a neurological disorder that relates to prolonged periods of motion.  Symptoms includes dizziness, fatigue, and nausea.  If the motion causing nausea is not resolved, the sufferer will frequently vomit.  Unlike ordinary sickness, vomiting in motion sickness tends not to relieve the nausea.


About 33% of people are susceptible to motion sickness even in mild circumstances ; the remaining 66% are susceptible in more severe conditions.  Individual and animals without a functional vestibular system are immune to motion sickness.


Cause

The most common hypothesis for the cause of motion sickness is that it functions as a defense mechanism against neurotixins.  

When feeling motion but not seeing it, the vestibular system in inner ear transmits to the brain that it senses motion, but the eyes tell the brain that everything is still. 

As a result of the discordance, the brain will come to the conclusion that one of them is hallucinating and further conclude that the hallucination is due to poison ingestion.  The area postrema in the brain responded by inducing vomiting, to clear the supposed toxin.


Types

Motion sickness can be divided into 3 categories :

1. Motion is felt but not seen
In these cases, motion is sensed by the vestibular system and hence the motion is felt, but no motion or little motion is detected by the visual system,  e.g. car sickness, air sickness, sea sickness, centrifuges, spinning.

Reading a book, a map or interior or the car, which are motionless, in a moving car/airplane/boat tends to easily motion sickness.  While visual system sees the motionless objects ( book, map or interior of car/airplane/boat ), vestibular system senses motion, especially vehicle goes around corners or over hills, which cause the discordance. 

The effect may be lessened by looking outside of the vehicle.
Yet, there is little that can be seen outside of a window of an airplane due to the small windows. 
Travelers on sea crafts too find it difficult to visually detect motion even if they look outside of the boat, as water does not offer fixed point with which to visually judge motion.

When one spins and stops suddenly, fluid in the vestibular system continues to rotate, causing a sense of continued spinning while one’s visual system no longer detects motion.


2. Motion is seen but not felt
Motion is detected by visual system, but no motion or little motion is sensed by the vestibular system.  It is also referred to as Visually Induced Motion Sickness ( VIMS ), eg. motion sickness due to films / virtual reality, simulation sickness, space sickness.

This type of sickness occurs when watching films on especially large screen or 3D, or even TV.  Films or home videos shot by handheld camcorder without image stabilization technology tend to contribute to motion sickness. 
Playing computer or video games too will cause motion sickness.


3. Motion sickness that are seen and felt but do not correspond
When moving in a vehicle for a long time on a badly maintained road at a very slow speed, the visual and vestibular systems fail to correspond which cause motion sickness.  Vibration of vehicle give sense of severe motion to the vestibular system, but due to the slow speed the visual system doesn’t sense proportional amount of motion.


Prevention & Treatment

Motion sickness can be cured or prevented by :

- Look out of the window of the moving vehicle and gaze toward the horizon in the direction of travel.  This helps to reorient the inner sense of balance by providing a visual reaffirmation of motion

- In the night, or in a craft without windows, it is helpful to simply close one’s eyes, or take a nap.  This resolves the input conflict between the visual and vestibular system.  Napping also helps prevent psychogenic effects ( the effect of sickness being magnified by thinking about it ).

- Chewing gum, snacking or just chewing in general seems to reduce adverse effects of the conflicts between visual and vestibular systems.

- Fresh, cool air also relieve motion sickness slightly.  As does avoiding foul odours.

- Get plenty of rest.   Weariness and exhaustion may induce motion sickness.

- Avoid acidic, spicy or oily food.   Avoid caffeinated beverages and soft drinks.

- Drink plenty of water.  Do not skip meals.  Don’t over eat.

- Medications such as Dramamine ( dimenhydrinate ), Stugeron ( cinnarizine ), and Bonine ( meclozine )

Tuesday, September 6, 2011

Water

Systematic Naming

The accepted IUPAC name of water is oxidane (H2O) or simply water.

The simplest and best systematic name of water is hydrogen oxide.

The polarized form of the water molecule, H+OH-, is also called hydron hydroxide by IUPAC nomenclature.

Dihydrogen monoxide (DHMO) is an overly pedantic naming of water.  Other systematic names for water include hydroxic acid, hydroxylic acid, and hydrogen hydroxide. Both acid and alkali names exist for water because it is amphoteric (able to react both as an acid or an alkali). While these names are technically not incorrect, none of them are used widely.



Electrical Properties

Dipole

Water is 1 molecule of oxygen covalently bonded to 2 hydrogen atoms, forms an angle ( 104.5° ), with H at the tips and O at the vertex.

Since O has a higher electronegativity than H, the side of the molecule with O has a partial negative charge.  An object with such a charge difference is called a dipole.   The charge differences cause water molecules to be attracted to each other and to other polar molecules.  This attraction contributes to hydrogen bonding, and explains many of the properties of water, eg. universal solvent, pH, adhesion, cohesion, capillary action, electric conductivity…   


Hydrogen bonding

A water molecule can form a maximum of 4 hydrogen bonds, because it can accept 2 and donate 2 hydrogen atoms. 

In water local tetrahedral order due to the 4 hydrogen bonds gives rise to an open structure and 3-dimensional bonding network, resulting in the anomalous decrease of density when cooled below 4°C.

Hydrogen bonding is responsible for a number of water’s physical properties, eg. high melting point, high boiling points, large specific heat capacity, large specific heat of vaporization, surface tension & capillary waves, density …







Physical Properties


Taste & Odor

Water is a tasteless, odorless liquid at standard temperature and pressure.


Transparency

Water is transparent to visible light, near ultraviolet light, and far-red light, but it absorbs most ultraviolet light, infrared light and microwaves. 

Most photoreceptors and photosynthetic pigments utilize the portion of the light spectrum that is transmitted well through water.  Thus aquatic plants can live within the water because sunlight can reach them.


Colour

The very weak onset of absorption in the red end of the visible spectrum lends water its intrinsic blue hue.


Density

The density of water is approximately 1 gram per cm3.   Yet it is very inconsistent. 

Although it is dependent on its temperature, the relation is not consistent.  At high temperature, it is less dense.  When it cooled from room temperature, the density increases.  At approximately 4°C, pure water reaches its maximum density.   

Upon freezing, the density of water decreases by about 95%.  Thus, the less denser solid water will float on denser liquid form.   

The reason of this is the water molecule forming hexagonal Ice lh formation.

These properties of water have important consequences in its role in the Earth’s ecosystem.  Water at 4°C will accumulate at the bottom of fresh water lakes. Ice will floats over the water surface, creating a blanket which prevent loss of heat of the liquid water beneath.  Thus it is unlikely a deep lake will freeze completely, thus help preserve aquatic life.


Surface Tension

Water has a high surface tension of 72.8 mN/m at room temperature, cause by the dipolar interactions, the highest of the non-metallic liquids.  

The effects of surface tension can be seen with ordinary water :
-         beading of water on  sorption-free surface ( non-adsorbent and non-absorbent, eg. polyethylene ).  Surface tension give water their near-spherical shape, because a sphere has the smallest possible surface are to volume ratio.
-         formation of drops.
-         flotation of object denser than water occurs when the object is non-wettable and its weight is small enough to be borne by the forces arising from surface tension.
-         separation of oil and water
-         tears of wine
-         emulsions are a type of solution in which droplets of oil suspended in water ( or vice versa ).


Capillary Action

Due to an interplay of the forces of adhesion and surface tension, water is able to flow against gravity where it spontaneously rises in a narrow space such as a thin tube, or in porous material such as paper or cloths.

Examples of capillary actions:
-         kerosene lamp’s wick
-         chromotography
-         water movement in plant’s xylem


Universal Solvent

Water is a good solvent.  Substances that dissolve in water includes : salts, sugars, acids, alkalis, some gases.

However, water cannot dissolve all substances, especially those that are non-polar or hydrophorbic in nature.


Electrical Conductivity

Pure water does not conduct electricity, thus an excellent insulator.  But there are no such pure that it is free of ions, even deionized water.  As water is such a good solvent, it  almost always has some solute dissolved in it. 


pH

Pure water is pH neutral, that is pH 7.0. 

But since there are no such pure water, as there are a lot of substances that dissolve easily in water.  It is thus, water’s pH is very dependent on dissolved chemicals and minerals, as does it changes over time.

Normally, water pH is < 7.0.   That explains metals rust upon contact with water.  Surface water are mostly acidic.

Water with pH > 7.0 is considered basic.  Sea water is basic in nature.
Water with pH > 8.5 is considered hard water.  Hard water contains high mineral content, especially Ca2+ and Mg2+.  Hard water is difficult to suds – difficult to produce soap bubbles.  It also forms deposits that clog plumbing.


High Boiling Point

Boiling point is when a substance reach a temperature at which the liquid state of the substance change to vapor, under atmospheric pressure.  Water has a high boiling point ( 100°C ) for its strong hydrogen bonding.  High boiling point means water is not easily vaporized by heat, thus a stable medium for living organism.


Specific Heat Capacity & Heat of Vaporization

Water has the 2nd highest specific heat capacity of all known substances, after ammonia, as well as high heat of vaporization, both of which are a result of the extensive hydrogen bonding between its molecules.

Specific heat capacity is the amount of energy required to change a substance’s temperature by a given amount. 
Ice’s specific heat capacity at -10°C is about 2.05 J•g-1•K-1.
Steam’s specific heat capacity at 100°C is about 2.08 J•g-1•K-1.

Heat of vaporization refers to amount of energy required to transform a given quantity of a substance into a gas at a given pressure. 
Water’s heat of vaporization is 2257 kJ•kg-1.

The high specific heat capacity and heat of vaporization of water help to moderate Earth’s climate by buffering large fluctuations in atmosphere temperature.

Sunday, August 14, 2011

Gizzard

The gizzard, also referred as the ventriculus, gastric mill, and gigerium.  In Mandarin, it is called 肫 ( pinyin : zhūn ), or 胗 ( pinyin : zhēn )  It is an organ found in the digestive tract of some animals, including birds, reptiles, earthworms, and some fish.  It is a specialized stomach constructed of thick, muscular walls, for grinding up food, often rocks are instrumental in the process.

The word ‘gizzard’ comes from the Middle English ‘giser’, which derives from a similar word in Old French, which evolved from the Latin ‘gigeria’, meaning giblets.

Birds swallow food and store it in their crop.   Then the food passes into their glandular stomach ( proventirculus – true stomach ).  Then into the muscular stomach ( ventriculus – gizzard ).  The gizzard can grind the food with previously-swallowed stones and pass it back to the muscular stomach, and vice versa.  The bird gizzards are lined with a tough layer made of the carbohydrate-protein complex koilin, to protect the muscles in the gizzard and to aid in digestion.

All birds have gizzards.  Some fish ( mullet, gillaroo, trout ), alligators, crocodiles, and most invertebrates too have gizzards.

Tuesday, March 8, 2011

Alcohol Flush Reaction

Alcohol flush reaction, AFR ( also knows as Asian flush, Asian red or Asian glow ), is a condition in which the face and/or body experiences flushes or blotches, due to an accumulation of acetaldehyde.  It is associated with the erythema ( reddening caused by dilation of capillaries ) of the face, neck, shoulder and in some cases, the entire body after consumption of alcohol.

Research has shown that alcohol flush reaction is indicative of ALDH2 deficiency.    The inability to process acetaldehyde in an efficient way leaves it to accumulate in the system.  Over extended periods, acetaldehyde can cause damage to kidney, liver and other tissues.   Research shows that an ALDH2-deficient drinker who drinks 2 beer per  day has 6 – 10 times the risk of developing esophageal cancel as a drinker not deficient in the enzyme.

AFR is estimated to be as much as 50% of the Asian population.  It is not known why such a high percentage of Asians posses the genetic makeup which linked to acetaldehyde dehydrogenase-2 ( ALDH2 ), which breaks down acetaldehyde, a product of the metabolism of alcohol.   Native Americans are highly susceptible to this condition as well.




C2H6O (ethanol)  →  C2H4O (acetaldehyde)  →  C2H4O2 (acetic acid)    →  Acetyl-CoA  →   3H2O + 2CO2 + Energy



Once alcohol enters the bloodstream, ADH ( alcohol dehydrogenase ) turns ethanol into acetaldehyde.  The gene coding for enzyme ADH is 1.1.1.1 on chromosome 4, locus 4q21-q23.

Then ALDH2 converts the acetaldehyde into acetic acid.    The gene coding for enzyme ALDH2 is  1.2.1.3 on chromosome 12, locus q24.2.   Acetaldehyde is a highly unstable compound and quickly forms free radical structures which are highly toxic if not quenched by antioxidants such as ascorbic acid and Vitamin B1.  

Conversion of acetic acid to acetyl-CoA is assisted by ACSS2.  The gene coding for ACSS2 is 6.2.1.1 on chromosome 20 locus q11.22.

Finally, acetyl-CoA enters citric acid cycle , and formed CO2, H2O and energy.

When the body is slow in converting the acetaldehyde into acetic acid, the acetaldehyde caused nausea, headache, drowsiness,  light-headedness, drop of blood pressure, blotched skin, facial swelling, fatigue, racing pulse, vomiting and even stomach bleeding.



Treating AFR

Anecdotal evidence suggests that ingestion of low doses of heartburn medicine, containing ranitidine or famotidine, may be able to relieve the body of symptoms if taken 30 – 60 minutes before drinking.  Although ranitidine has been proven to significantly increase blood alcohol content.

Experts suggest that consuming certain food before drinking may help.  Some say that food that contain starches may coat the stomach, thus reducing the ingestion of alcohol.  Some suggest that sugary foods may help reduce the effects of AFR.

However, there is currently no permanent cure for AFR.  The fact remains that alcoholism rate are lower among Asians groups, possible due to the adverse reaction of AFR.

While it may be embarrassing and uncomfortable, our body discomfort towards alcohol should be treated as a sign that something is not right within our body.  It’s important to follow our body’s response to reduce or avoid harm or damages to our body.

Tuesday, February 1, 2011

Tenualosa toli - Terubuk

kan Terubuk is Tenualosa toli, a shad of the Clupeidae family, available in western Indian Ocean and the Bay of Bengal to the Java Sea, and the South China Sea. It inhabits fast-flowing, turbid estuaries and adjacent coastal waters.


Terubuks are Hermaphrodites protandrous . Meaning that, male terubuks can produce eggs. Males spawn in their first year, then return to spawn as females in the next season. After this, they die. A short 2 years-plus lifespan. The males are called empirit, and the females, terubuk.

Survival rate of terubuk hatchings is 1 or 2 out of 500,000 ! Which explains the decline of the fish population in Sarawak waters. Thus, it is not surprise to learn that most salted terubuk consumed in Malaysia is imported from Indian and Bangladesh.

Overfishing and loss of habitat has depleted the population alarmingly in S.E.Asia, with only Sarawak left as its only habitat. Terubuk used to be found in the Straits of Malacca, but siltation of estuaries due to tin mining, caused its extinction.

5 medium size ( about 20cm length ) of salted terubuk fish, weight about 1 kg, cost RM25. Salted terubuk eggs cost about RM300/kg.