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Science communication is important in today's technologically advanced society. A good part of the adult community is not science saavy and lacks the background to make sense of rapidly changing technology. My blog attempts to help by publishing articles of general interest in an easy to read and understand format without using mathematics. I also give free lectures in community events - you can arrange these by writing to me.

Monday, 27 July 2015

Stress Free Way to Control Body Weight

For the past forty years, I have maintained my body weight at 65 +- 1 Kg  – HOW?

Not a day passes when one does not come across some advice on the subject of losing weight.  Most advice is from commercial concerns who want to promote their products or from health professionals who present a doomsday scenario demanding that we lose weight and help control the imminent ‘obesity epidemic’.  In reality, most people are happy with the way they are; the social pressures that these advertisements and news stories put on us are partly to blame for the unhappiness that some people might feel about their weight.  Generally, most weight control measures fail in the medium or long term, and in many cases the results have been harmful.
The thing to appreciate is that each person is unique and has his/her own metabolic rate, eating preferences, aptitude to exercise etc and there is never going to be a general prescription to suit everybody. Also, the working of the human body is finely balanced and every new weight control measure, that tries to modify the nutritional intake the body is used to, is bound to have repercussions in some other aspects. 
In this feature, I use my personal experience to promote a sensible, common sense approach to maintaining weight that you are most comfortable with.  For the past forty years, I have maintained my body weight at 65 Kg within a range of 1 kg without ever going to the gym.  My height is 168 cm with a body mass index (BMI) of 23.  How do I do it? – It is simple - with zero stress.
Zero stress is the most important criterion for any weight control regime.  What is the point of changing your weight if it causes you worry (because you want to conform), tiredness (you are not eating enough calories or eating tasteless food), exhaustion (spending endless hours in the gym to burn those calories)?  Whatever age you are, you have reached a situation that you are more or less satisfied with – you are a product of your life style and the environment you live in.  Changes are always stressful – and weight reduction is no exception.  That is why, any attempt to lose weight has to be in harmony with your current life style and not create tensions and pressures – otherwise it is bound to fail.
Another reason why weight control methods do not work is because they are not natural – most appear to be intrusion - are too scientific, requiring continuous counting of calories etc.  Eating is a natural process and nobody likes to be told what to eat and what not to eat.  But that is how the system is just now – you appear always to be ‘guided’ to a better life and health. It just does not make sense. Nonsense, I call it.
How do you control your weight?  This has to be a slow gradual process – best done over a year or more. Essentially, you are incorporating weight control into your life style and you want to do it without stress. Everything you eat gives energy to your body. The body needs a minimum amount of energy to function – even if you do absolutely nothing in a day, your body will need a minimum amount of energy to survive.  I shall use round numbers – so say we need 1000 Calories to survive. Each activity uses energy – walking, running, thinking, reading whatever you do needs energy.  The more vigorous the activity, the more energy you need.  They say that a normal active man/woman needs (in round numbers) 2500/2000 Calories per day.  If your intake of food is greater then the extra Calories will be stored in the body and you will gain weight.  If it is less, body will burn stored Calories – in the form of fat or carbohydrate – and you will lose weight. Adding fibre to your diet helps to lose weight. Rule of thumb numbers are: 
Consume 100 Calories less per day to lose 1 pound/month or about 5 kg/year
Add 10g extra fibre per day to reduce weight by 3 kg/year  
To control your weight, you do not need to calculate how many calories you are consuming just now, or what your level of exercise is or anything else – you are what you are and you have a lifestyle that suits you.  If you have a steady weight then you are probably consuming roughly 2500/2000 Calories. How do you lose 5 kg/year? The simple answer is that you lose 5 kg/year by reducing your food intake by 100 Calories per day – this is reducing the amount of food you eat by about 5%.
What does that mean?  Reduction of 5% in food intake can be achieved by a variety of simple stress free means.  Your activity/exercise level can stay exactly what it is now. Remember that energy content of the food is different for different types. It is:
Carbohydrates and Proteins –      4 Calories per gram
Fats                                                    9 Calories per gram
To cut 100 Calories per day, you can simply reduce the size of the portions by 5%.  Use a smaller glass for your juices and wine.  Take a few percent smaller portion at meal times or just miss out a couple of biscuits or a crisp packet. But do it daily.
When I was young, they told me to chew each bite 32 times.  This improves digestion and helps the body to get the maximum benefit from the calories you consume.  I must confess, I don't chew my food 32 times but do take my time to finish the meal - eat slowly.  It is a good habit and has some scientific basis too. We feel full because the stomach sends a signal to the brain which decides when to tell you to stop eating. There is a few minutes time lag and we end up eating more than required. Eating your food slowly helps to optimise the quantity of food. Fewer heart burns too!
Because your life style does not need to change, you can still binge once in a while as you do now – nothing needs to change at all. 
There are several other things that you can also do.  For example, do not measure your weight more than once a week – weight control must not be an obsession – stress can make you consume more food.  Talk to your family and friends that you are reducing your food intake by 5% to lose 5 kg/year. Just be relaxed about the whole thing – you will benefit more by continuing as you always did but with simple measures that I have described above.      

Blog Contents - Who am I?        

Tuesday, 21 July 2015

Climate Change - Atmospheric Air Circulation, Convection Cells, Coriolis force, Jet Strems

Atmospheric circulation is the large-scale movement of air, and the means (together with the smaller ocean circulation) by which thermal energy is distributed on the surface of the Earth
Essentially, the Earth gets all its energy from the Sun with much more of the energy arriving in the equatorial regions - the higher latitudes receive much less of the Sun's energy.  This increases the temperature of the sea water and land in the tropics near the Equator relative to the polar regions. (see the following 6 slides).  The heat is transferred from hotter to colder regions by ocean currents and by the movement of the atmospheric air.
SLIDE 7:  The air near the surface absorbs heat, becomes less dense and rises. Cooler air moves in to fill the space. The hot air cools as it rises. Colder air is more dense and sinks to the surface and absorbs more heat again.  This completes a closed convection cell.
This is exactly the science behind air circulation.  If the Earth did not rotate then air circulation will look as in slides 8 and 10.  Slides 9 and 10 show that the wind direction at the surface will be from the Poles to the Equator. But our planet rotates and the rotation exerts an additional force, called the Coriolis Force on the moving air masses.  Coriolis force is described by slightly more complicated physics - basically, it is
(i) always perpendicular to the direction of motion of the air mass, and
(ii) is proportional to the speed of the air mass
Slide 11 shows how the Coriolis force will cause eastward deflection of air that is moving towards the North Pole and the deflection will be westwards if the air is moving from the Pole towards the Equator - in the Northern Hemisphere. In the Southern Hemisphere, the effect is reversed
It is because of the Coriolis force that a low pressure system in the northern hemisphere rotates counter-clockwise - explained in Slide 12.

In a rotating earth due to Coriolis force the convection cell does not extend from the equator to the Pole.  As the air mass is moving north, Coriolis force pushes it eastward and after some distance the air is actually moving from west to east and not as originally from south to north.  By the time air reaches 30 degree N, it is no longer experiencing the pressure gradient and sinks down completing a smaller convection cell - this is the Hadley Cell.
But heat still needs to be transported to the poles.  this happens with two additional cells - the Ferrel and the Polar Cells - in each hemisphere.
Jet streams are fast flowing, narrow air currents.   The main jet streams are located near the altitude of the tropopause. The major jet streams on Earth are westerly winds (flowing west to east). Their paths typically have a meandering shape.  The last three sildes explain the characteristics of jet streams.
Slide 7:  A Convection Cell
Slide 11:  Coriolis Force

Blog Contents - Who am I?

Monday, 20 July 2015

Climate Change - Oceans; their role in climate control; problems caused by human activities

The other day, somebody said to me that if we control the emission of CO2 and hence its concentration in the atmosphere then climate change (CC) effects will not be serious and earth’s temperature rise will not do much harm. The news about our Sun going into a quiet phase and rumours of the onset of a ‘little ice age’ in 20 years with temperature dropping by 0.3oC created lot of short-lived excitement this month. The Sun and the atmosphere are important in determining our climate but the part played by oceans in stabilizing and controlling the global climate is not widely appreciated.  Many people live hundreds of miles away from the sea and it is not surprising that their culture and traditions do not include the sea as an important player in determining the climate they enjoy.
The key word here is energy – oceans hold 1000 times as much thermal energy as the atmosphere does.  The atmosphere and the oceans continuously exchange heat energy and many of the weather events, some extreme, happen as a result of this interaction.  Oceans have vast thermal capacity and changes to ocean parameters like surface water temperature, sea levels etc happen on a slow time scale. The climate changes slowly while the weather (largely determined by the atmosphere) can change abruptly in a very short time.  Oceans play a crucial, I would say a controlling, role in determining climate change.  Oceans also have a series of positive feedback loops that can magnify small changes to create run-away climate conditions. Oceans are vast but the stability of our oceans depends on delicately balanced parameters.  Human activities are adversely affecting these parameters with serious implication for the global climate and the well being of our civilization.

Earth’s climate is determined by an interaction of a large number of parameters, some of them not very well understood.  An example is the IPCC projection of a sea level rise of approximately one meter by the year 2100 if the earth’s temperature rises by 2oC.  A recent study suggests that historically when temperatures have risen by 2oC, the sea level rise actually was on average 6 meters.  With current energy usage projections, emission of CO2 continues to be such that a temperature rise of 4oC or 5oC is more likely by 2100. How the coastal areas, where a significant proportion of the world’s population lives, and a large number of island states will be affected is worrying.
Human activities are responsible for many other problems causing deleterious effects on the oceans. For example, industrial and agricultural activity on land generates a large amount of chemical waste, some of it highly toxic – like dioxin, PCB etc.  In time, these chemicals reach the ocean and are taken up by phytoplankton and algae – the base of the ocean food chain responsible for up to 60% of global photosynthesis.  The bio-accumulation of toxins moves to higher members in the food chain, including humans, with accumulation of toxins multiplying by hundred of thousands times.
A second example of how human activity is causing untold harm to ocean life is the plastic pollution.  Again, a lot of rejected plastic finds its way to the sea where it floats on the surface, broken-up by waves into microscopic particles and collected in large area by the ocean circulation currents.  Some of these garbage areas are huge with plastic particulate numbers exceeding plankton counts.  These are ingested by sea creatures and cause a host of problems including death. 

In the following I am publishing the slides of my talk on Oceans given in 2011 in Glasgow.  Some of the slides have been updated but largely the scientific understanding is what was available at the time of my talks. 
(click on a slide to view its bigger image)