ektalks

Friday, 14 June 2019

Index of Blogs (2018-2019) and Courses

Click here For Blogger Profile
Click here for list of Talks and Blogs prior to 2018

Click on a date to view BLOG

6 January 2021 Colours in the Environment: PART 1: Sky, Clouds, Sunsets, Twilights, NLCs; Some Fascinating

Physics in Play; Interaction of Light with Matter

27 November 2020 Artificial Light at Night is a Rapidly Growing Problem with Serious Health

& Ecological Implications; Solutions are Relatively Simple:

A Public Information Feature

24 October 2020 Colour of Objects: Visible Light Spectrum; Primary Colours;

Optical Illusions; How Do Colours Work?

13 October 2020 Net-Zero by 2050 - How does One Eliminate Emissions from

Agriculture, Heavy Transport & Industry?

_A Community Education Feature

31 August 2020 Climate Change - Present Status & Future Prospects:

Talk at WES (Scotland)

17 August 2020 Biodiversity Loss in the Anthropocene; Impact on Human Welfare

4 August 2020 What is Light? All You Need to Know - A Community Education Feature

16 July 2020 Climate Change - Awaz Radio, Glasgow 15th July 2020
27 May 2020 IMO 1988 Problem 6: General Term Using School-Level Maths

10 February 2020 Big Data, Artificial Intelligence and Freedom -

Cyber Dystopia and Beyond

24 January 2020 7.75 Billion and 415 ppm; 4C Warmer World is Really Bad News

18 December 2019 Climate Change; Indecision at COP25 in Madrid;

Fiddling as the Planet Burns

18 December 2019 Making Sense of our Climate Change:

6. Carbon Isotope Studies Prove That Human are

Responsible for Global Warming

14 December 2019 Making Sense of our Climate Change:

5. Carbon Cycle and the Keeling Curve

10 December 2019 Making Sense of our Climate Change: 4. Global Warming Indicators

2 December 2019 Isaac Newton_Troubled Genius: 1. Family Tree; Early Years

1 December 2019 Making Sense of our Climate Change: 3. The Science of Global Warming

19 November 2019 Making Sense of Our Changing Climate: 2. Weather and Climate

17 November 2019 Making Sense of Our Changing Climate: 1. Introduction

1 November 2019 Outdoor Air Pollution in Delhi - an Update

3 October 2019 Common Sense and Superstitions - Personal, Cultural,

Spiritual and Scientific Dimensions

11 September 201 9 Limits to Sustainable Human Energy Production
13 July 2019 Pillars and Sinks of Healthy Ageing

26 June 2019 Longevity and Quality of Life - Lifestyle and Chronic Diseases -

It is Time to Reflect on How We Live
5 May 2019 SLEEP (Part 2): Why Do We Need to Sleep?

The Science of Sleep & Circadian Rhythm

12 March 2019 Air Pollution (Part 2) - Particulate Matter PM10 and PM2.5 -

Brake and Tyre Wear are Higher Emitters than Car Exhausts

21 January 2019 Global Greenhouse-Gas (GHG) Emissions by Humans and Animals

11 January 2019 SLEEP (Part 1): Why Do We Need to Sleep Eight Hours per Day?

Malaise caused by Impaired, Insufficient Sleep

27 December 2018 Routines; Habits and Addiction; An Outreach Feature

16 December 2018 Are the Young More Creative/Innovative? - Not Really (Part 2)

09 December 2018 Are the Young More Creative/Innovative? - Not Really -

Another Example of Perils of Perception (Part 1)

28 November 2018 Ethics of Eating Meat - We Need to Factor-in Sustainability

26 November 2018 A Magic Square based Party Game

25 November 2018 Why Do Humans Have two Front-Facing Eyes?

An Analysis & Some New Ideas

17 November 2018 Air Pollution (Part 1) - The Invisible Killer;

Particulate Matter PM2.5

27 October 2018 In Praise of BMI: Not Perfect But an Exceedingly Useful and

Convenient Parameter for Measuring Obesity

23 October 2018 Over-population is 'Elephant in the Room';

Why Do We Not Address the Real Problem?

21 October 2018 Recreational Maths with Smartphone Calculator -

10 Games to Wow Your Friends

16 October 2018 Additive and Multiplicative 3X3 Magic Squares -

Construction and Some Not So Well Known Properties

6 October 2018 Obesity in Children - Weight at Ages 3 to 6 is Critical in

Determining Obesity in Later Life

21 September 2018 Perimeter and Area of Regular Polygons -

From Triangles to Circles - The Iso-Perimetric Theorem

9 September 2018 The Rise of Tech Companies - Threat to Privacy and Freedom -

Cyber Dystopia

11 August 2018 A Simple Estimate of Global Mean Sea Level Rise due to

Increase in Global Temperatures

3 August 2018 Myths and Hypes about the Ubiquity of the Amazing Golden Ratio;

Its Relation to Fibonacci Numbers; Logarithmic Spiral, Phyllotaxis

and the Pentagram

6 July 2018 Derivation of nth Term of a Lucas Sequence -
Fibonacci Numbers and the Golden Ratio

7 June 2018 Enhanced Reactivity of Powders, Number of Surface Atoms;

Inter-Atomic and -Molecular Forces

31 May 2018   Sum of Powers of Digits in a Number -
Iterations lead to a Fixed Point or a Limit Cycle
25 May 2018      Optimal Car Separation at Traffic Lights -
Current Driving Habits Require a Rethink
21 May 2018   Surface to Volume Ratio for a Spheroid,
Cylinder, Cone and Rectangular Box - A Quantitative Analysis
13 May 2018     Climbing a Conical Mountain -- Almost Impossible
Shortest Path, and a Realistic Path You Can Use
29 April 2018   A Couple of Challenging Geometry puzzles - Created by
Martin Gardner - Recreational Mathematics
22 April 2018     What is the Number(s) of the Torn Page/Pages? -

Two Seemingly Impossible Puzzles
18 April 2018 Division of a Huge Cake: An Interesting Mathematical Puzzle
21 February 2018 Undefined/Indeterminate Mathematical Operations

Involving Zero and Infinity lead to fallacies and paradoxes
18 February 2018 Physics of Humidity, Relative
Humidity, Health Implications of Low or High Humidity

12 February 2018 Letter Frequency in Spellings of Words and

Numbers in the English Language
8 February 2018 Math Puzzles - How logical approach makes

them much more delicious
30 January 2018 The Awesome Number 2 : Puzzles, Games,

The Power of Doubling
28 January 2018 Number Puzzles for Mental Arithmetic Enthusiasts

26 January 2018 The Science of Hypothermia, Windchill, Frostbite - When

Body's Thermal Regulation Mechanism is Unable to Cope...

23 January 2018 The Science of Heatstrokes (Hyperthermia) -

When Body's Thermal Regulation Mechanism

is Unable to Cope...

16 January 2018 Heat given off by a human body is about 100 Watt

15 January 2018 Galileo Galilei - Family Tree, Friends and Foes

Contact email: ektalks@yahoo.co.uk

Courses - Each course is 8 to 12 hours duration. Courses are suitable for 'inquisitive' laymen with no serious science background. The courses are designed for outreach activity, non-mathematical and have been given in East Kilbride (Scotland) and other venues.

Please click on a course to start:

Albert Einstein and his Theories of Relativity

Nuclear Physics

Climate Change

Sustainable Development

Medical Imaging

Great Scottish Inventors
James Watt
Lord Kelvin
Alexander Fleming
Alexander Graham Bell
James Clerk Maxwell

Nano Technology

Nuclear Weapons - The story of the Atomic Bomb

Age of the Earth & Milky Way

(Radio-isotope Dating)

Sunday, 5 May 2019

SLEEP (Part 2): Why Do We Need to Sleep? The Science of Sleep & Circadian Rhythm____ A Community Education Feature

Who am I? Blog Index

When people ask me: “what’s more important, diet or exercise?”
I typically answer: “sleep.” Dr. Nalini Chilkov

(This part was used for a talk at the Burnbank Centre, Hamilton, Scotland in April 2019)

Sleeping seven to eight hours a day is essential for adults. In Part 1, I have discussed the evidence from recent scientific research about the relevance of sleep for humans and animals with the clear message that sufficient sleep (7 to 8 hours) is not only important for our physical and mental health/welfare, but a lack of good quality sleep has many serious unwelcome consequences (See slide below for a summary).

(click on the slide to see full page image; press Esc to return to text)

People who sleep too little or too long have increased chances of dying and occurrence of major cardio-vascular events. It is recommended that adults sleep 8 hours per day but children should sleep somewhat longer depending on their age.

Along with good diet, clean water, clean air and adequate exercise, sleep is one of the five pillars of good health.

Electrical Activity of the Brain and Sleep Cycles: Our brain controls most body functions through electro-chemical signals. The neurons in the brain are actively talking to each other. In fact, human brain weighs 1.3 kg (about 2% of the body mass) but is responsible for consuming about a quarter of the base metabolic energy (the brain's energy consumption is ~600 Calories per day).
Interestingly, the brain uses as much energy when we sleep as it does when we are awake - even more during some periods of sleep.
When awake, we are interacting with the world around us - thinking and making decisions, and a large amount of input is provided to the brain from objects and events around us.
When sleeping, the brain is certainly not interacting with the outside world and the question is - what is the brain using the vast amount of energy for?

Let us first look at the way the electrical activity of the brain is measured and point out the differences & relevance of different types of sleep.

An EEG, electroencephalograph, collects electrical activity from the brain and plots the signal as function of time. The wavy pattern tells us what is happening in the brain. One can study signal from individual parts of the brain to learn how active different parts of the brain are at any particular time.

Despite a large amount of descriptive information about the various stages of sleep, the functional purposes of the sleep states are not known. Whereas, most sleep researchers accept the idea that the purpose of non-REM sleep is at least in part restorative, the function of REM sleep remains a matter of considerable controversy.

In the following slides, I shall present typical electrical activity of the whole brain during when you are awake and in different phases of sleep.

A healthy adult sleeps 7 to 8 hours per day and cycles between different stages of sleep in a consistent manner - generally there are 5 cycles, each lasting 90 minutes. The electrical activity of the brain may be represented on a hypnogram - a record of the stages of sleep as a function of time - generally plotted in 30 sec intervals. A typical situation is shown in the slide:

Most slow wave sleep (NREM3) occurs in the first two cycles while REM sleep dominates the last two cycles before waking.

Sleep is also essential for disposing metabolic waste from the brain - this is explained in the next slide

Molecules that Make Us Sleep: There are two ways human body feels sleepy.
1. Circadian rhythm causes secretion of hormone melatonin at certain time of the day (at the onset of darkness). Melatonin tells the body that it is time to rest and sleep. More of this later...
2. The chemical adenosine acts as a sleep-inducing (hypnogenic) molecule. Adenosine is produced by the break up of adenosine triphosphate (ATP) during energy generation to power bodily functions. The activity of the neurons and gilial cells causes a build up of adenosine in the brain and this increases the sleep pressure. After 12 to 16 hours of wakefulness, the level of adenosine and hence the sleep pressure reaches a high value and one has a strong desire to sleep. During sleep, adenosine is destroyed and after 8 hours of sleep, adenosine levels reach a low value with a correspondingly weaker sleep pressure. This is shown in the slide:

Adenosine works by attaching itself to receptor sites in the brain to induce sleep pressure. Substances like caffeine have similar molecular structure to adenosine and are present in tea, coffee, coke and many other food items. Caffeine attaches to adenosine receptors in the brain and prevents the build up of sleep pressure. That is why, it is advisable to avoid caffeine 4 to 5 hours before sleeping time in order to ensure a good night sleep.

Circadian Rhythm (Internal Biological Clock):
Different body functions rise and fall at set times of the day based on your circadian rhythm. Your circadian rhythm controls when you should sleep and when you should be awake (alert and active).

Additional Recent Information: Night owls: Simple sleep tweaks boost wellbeing (10 June 2019)

Final Word: Good quality sleep of 7 to 8 hours is absolutely essential for adults - children need more. The benefits are huge ..

The science of sleep is fascinating and, like anything else in the human body, complicated. I am really curious to learn about the dreams - why do we dream and what is the purpose - as I had said in part 1, evolution does not do anything without a reason - there must be an important function that dreams serve - we just need to find it. Wait for part 3...

Please pass on the link to friends and family; sleep is an important enough topic to worth shouting about.

Please click here for PART 1 https://ektalks.blogspot.com/2019/01/sleep-part-1-why-do-we-need-to-sleep.html

Recent references: https://www.medscape.com/viewarticle/914244_1

Tuesday, 12 March 2019

Air Pollution (Part 2) - Particulate Matter PM10 and PM2.5 - Brake and Tyre Wear are Higher Emitters than Car Exhausts

Who am I? Blog Index

In Part 1, I had discussed the nature and adverse health effects of outdoor air pollution that is particularly serious in almost all major cities and is responsible for nearly 5 million deaths annually. In cities, road transport is a major source of air pollutants - particularly particulate matter - the subject of this publication.
In Central London, road transport is responsible for 54% of particulate matter PM10 (all particles less than 10μm diameter) emissions and for 48% of the harmful oxides of nitrogen.
The issue of transport in cities is a complex problem - petrol and diesel vehicles are generally blamed for the pollution. However, under the new low emission legislation, pollution from exhausts has been falling and the main problem in future will be particulate matter generation by brake wear and tyre wear (BWTW), road surface wear and other particulate matter that already exists in the environment and become suspended due to traffic induced turbulence. Non-exhaust emissions are equally important for electric vehicles (EVs) and it seems that PM emissions will continue to be a serious health hazard in cities until a better way to move people is found.

Airborne PM2.5 are capable of bypassing human noses and throats, penetrating deep into the lungs where they deposit harmful chemicals adsorbed on their surfaces. Their presence has been linked to a number of health conditions, including respiratory illnesses (for details, see Part 1).

Experts estimate that by 2030, as the transport sector moves into electric vehicles, 90 per cent of harmful PM2.5 emissions will be caused by microscopic particles eroding from tyres & brakes and particles airborne from road and surrounding surfaces.

The UK government's clean air strategy plans to develop new standards for tyres and brakes to address toxic non-exhaust emissions. Similar planning is underway in most major economies. At the same time, the size of cities is growing rapidly with 75% of the world population expected to live in urban areas by 2050 with a corresponding increase in road traffic and emission of particulate matter.

New products and technologies are crucial in achieving clean air in our cities - for example, Bosch has recently launched a new iDisc brake disc with a tungsten carbide coating that emits 90% less brake dust than a conventional cast iron disc. Regenerative braking, most effective in stop/start driving typical of the traffic in cities, in hybrid and electric vehicles (EVs) reduces the need for friction braking greatly, thus cutting down on particulate emissions. More on this later.

In this publication, I look at the non-exhaust particulate emission in more detail and discuss what may be done to improve the quality of outdoor air. Unlike exhaust emitted particles, there are no standard methods for characterising non-exhaust particulate matter and it is sometimes difficult to compare results of different studies. A good estimate of how much particulate matter (in mg per km of travel) is emitted is provide by the following figure

Concentrating on PM2.5 particles, we note that heavier cars generate greater quantity of particulate matter - that is why large scale adoption of battery electric vehicles (BEVs), which tend to be heavier than internal combustion engine vehicles (ICEVs), will not reduce tyre or road wear. However, in urban driving, BEVs will almost totally eliminate brake wear due to regenerative braking - for example, BMW i3 does not generate any brake dust for 90% of the time.
Fuel Cell Electric Vehicles (FCEVs) are much lighter and hold good promise over battery electric vehicles (BEVs) in reducing non-exhaust emissions of PM2.5.

Other measures for reducing PM2.5 emissions could be the use of drones for delivery of parcels in the city and use of Internet to send documents instead of paper. Both will reduce the number of vehicles on the road.

Greater use of public transport will help too as well as pedestrianisation of central city areas to exclude road traffic.

Self-driving electrical vehicles (AEVs) will be much lighter than today's BEVs. As a taxi service, AEVs can be right size for the purpose - for example, for transporting one or two people, a two-seater AEV is all that is required. Due to their better safety characteristics, AEVs can be made of lighter materials saving on fuel and reducing PM2.5 emissions from tyre and road wear. Introduction of AEVs will also reduce the number of vehicles in the urban surroundings.

Most big cities have a subway system where ventilation is not very efficient and the air quality tends to be poorer. Non-exhaust emissions are the most important source of airborne particulate matter in the subway system, including platforms and trains. Subway PMs are mostly iron and carbon based particles and are generated from rail-wheel-brake interfaces. Trains and ventilation systems drive the particles along the tunnel and mix them with dust etc. More effective ventilation systems, magnetic filters and platform screen doors will help to reduce the concentration of PMs on the subway platforms.

Monday, 21 January 2019

Global Greenhouse-Gas (GHG) Emissions by Humans and Animals - An Outreach Feature

Who am I? Blog Index

Nothing will benefit health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet. ...Albert Einstein (quoted)

Greenhouse gases (GHG - mostly carbon dioxide CO2, methane CH4 and nitrous oxide N2O) in the atmosphere trap heat radiated from the Earth and keep it at a comfortable temperature of 14C . Without GHG the Earth will be about 32 degrees colder with an average temperature of -18C - life would be impossible. During an ice age, the average global temperature only falls by about 7 to 10 degrees.

Since the first industrial revolution, humans have been putting more CO2 and other GHGs in the atmosphere with a sharp increase in the 20th century. Population numbers have gone up too; the following slides show the steep rise in GHG over the past 100 years. This has resulted in the Earth warming by about 1C over this period.

In 2017, total CO2 emissions from fossil fuel and industry were 36.8 billion tons; CO2 stays in the atmosphere for over 100 years.
Total annual methane emissions had reached 623 million tons in 2016.
The residency time of methane in the atmosphere is about 12 years.

(Click on a slide to see its full page image, press ESC to return to text

Methane is a potent GHG. Over a 20 year period, methane has 86 times greater global warming potential than carbon dioxide. Many publications quote a global warming potential of methane as 26 over a 100 year period.

We normally attribute the rise in GHGs to increased industrial, transport and agricultural activity based around the burning of fossil fuels (coal, oil and natural gas). Most publications do not discuss GHG emissions due to metabolic activity in humans and their livestock, both have increased fourfolds in the past 100 years.

I shall estimate such metabolic contributions using 'back of the envelope' calculations. The simple calculations give surprisingly realistic results and help the non-specialist general population to understand this aspect of the science behind global warming.

GHG Emission by Humans and Animals:
Are we heating the planet as we breathe?

Many news articles mention the role of cattle in emission of the greenhouse gas methane, but it is not widely appreciated that humans and animals also emit significant amounts of CO2 which contributes to the GHG budget and to global warming. I shall estimate these numbers in the following:

Carbon dioxide emission by humans: Humans inhale atmospheric air containing CO2 at 0.0004% concentration but exhale air with CO2 at 5% concentration. (I shall use rounded numbers for ease of calculation).
The following slide provides more details:

CO2 is a product of metabolic activity (respiration). While it is possible to calculate the amount of CO2 emitted by using volume of exhaled air and breathing rate (I have described the calculation at the end of this blog), it is easier (and probably more accurate) to work out the amount of CO2 produced per day by the aerobic respiration reaction in which glucose uses oxygen to produce energy, water and CO2.
For our purpose, it suffices to say that carbohydrates in the food are broken down to glucose molecules and the reaction may be written as

Glucose + Oxygen -> Water + Carbon dioxide + 2886 kJ Energy
C6H12O6 + 6 O2 →   6 H2O + 6 CO2 + heat

Essentially, one molecule of glucose uses 6 molecules of oxygen to produce 6 molecules of CO2. The molar weight of glucose is (calculated from its formula) 180 and that of CO2 is 44.
This means that 180 gram of glucose burns to produce 6 x 44 = 264 gram of CO2.
Assuming that we consume 2000 Calories per day and carbohydrates produce 4 Calories per gram, we are burning equivalent of 500 gm of glucose per day in aerobic respiration.
This will produce 500 x 264 /180 = 733 grams of CO2 per day or 268 kg/year.
Each of us produces this amount of CO2 per year. The world population is over 7 billion and will produce 1.87 Billion Tonnes of CO2 per year.  This is 5.2% of the total CO2 put into the atmosphere by human activity.

What about Animals? The main population of animals is comprised of those reared for human consumption - cattle, sheep, pigs, poultry etc. Their numbers have sharply increased in response to increasing human population and higher demand of meat over the past 50 years or so.

Additionally, there were about 23 billion poultry in the world in 2014.
Livestock animals exhale CO2 generated in the respiration process - most amount is exhaled by cattle which are much bigger in size than other livestock animals.

The metabolic energy requirements of a mammal vary as 0.75 power of the body mass, we can calculate for a given body mass how much CO2 per day an animal will produce. The table shows the amount of CO2 exhaled by livestock animals. The emissionn of methane is also given.

In conclusion, humans and livestock release
1.87 + 6.65 = 8.52 billion tons of CO2 in the atmosphere per year. This number has increased fourfold in the past 100 years. Only China emits more CO2 than humans and animals exhale (2015 figures in billion tons per year: China 10.6 and USA 5.2)!

Methane Exhaled by Livestock: The table above
gives methane emisssions from various livestock animals.  Meat cattle are the main source of methane. Exhalation represents about 96% of total methane put into the atmosphere by the cattle - there is a common misunderstanding that cattle emit methane by farting but that only contributes a tiny %. Most exhaled methane is produced in rumination.

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Wiki explains: Ruminants are mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The process, which takes place in the front part of the digestive system and therefore is called foregut fermentation, typically requires the fermented ingesta (known as cud) to be regurgitated and chewed again. The process of rechewing the cud to further break down plant matter and stimulate digestion is called rumination.
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Currently, we are putting in 623 million tons of methane in the atmosphere every year. Of this 110.7 million tons ( ~ 18% is emitted by livestock rumination - enteric fermentation or EF). These numbers have been revised upwards by 11% in 2017 by Wolf et al. In 2010, EF accounted for 43% of all GHG emission from agricutural activity in the world.

Remember that biggest increase in methane emissions is due to meat cows and pigs (their numbers have gone up fivefold over the last century); more people are consuming meat that will only make the situation worse.

Manure Treatment is a serious source of Methane too:
It is not only that livestock exhale methane (product of the rumination process in cattle) but the storage and treatment of manure from the livestock is also a serious source of methane.

Manure is stored in tanks, lagoons where microbial activity causes its deacy. Anaerobic breakdown produces greater amount of methane and a switch to aerobic decay will reduce the emission of methane.

Final Word: In this blog, I have used the population numbers and emission of carbon di-oxide and methane by individual animals to calculate the total contribution to GHG emossions that humans and their livestock make. Additional emission will also come from other animals that I have not considered.

The warming of the world due to GHG emissions is predicted to reach at least 2 degrees centigrade by the end of the century. Human and Livestock emissions can be most effectively reduced by population control - while the human population is supposed to stabilise around the 10 billion mark in the next 50 years, livestock population can only decrease if we change our emphasis to eating meat - this is a trend that has a lot of mementum and is unlikely to change in the near future.

Better manure management (using aerobic storage tanks) will help but that is not the major contribution. Pasture grazed cattle emit less methane but again it is not a practical solution if we all insist on eating meat-rich diet.

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Thanks for reading...