For introductory remarks for the course see
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Monday, 10 August 2015
The Nucleus - Talk 2: Radioactivity, Discovery, Nuclear Decay Modes, Applications of Radioactivity
Index of Blogs and Courses
For introductory remarks for the course see
For introductory remarks for the course see
The Nucleus - Talk 1 - Introduction, Discovery and Properties
The Atomic Nucleus and Nuclear Energy - Talks for ScienceforAll Outreach Programme
Study of the atomic nucleus is a rewarding endeavour. It all started as a serendipitous discovery of radioactivity of uranium in 1895; and Marie Curie's hard labour elevated the study of the nucleus to a separate and distinct branch of physics.
The nucleus of an atom is a fascinating object - in day to day life, we are not aware of its existence. But what goes on inside a nucleus has far reaching implications. The world around us works in an electron Volt (eV) regime. (In a 1.5 Volt battery, an electron gains an energy of 1.5 eV in going between the negative and positive elctrodes). All chemical, biological and optical processes operate in the eV energy regime. Nuclear processes operate in the MeV (million electron Volt) regime - energies involved are much much higher - researchers had to develop a lot of new instrumentation and methods to study the nucleus.
The study has been rewarding bestowing great benefits to our society. Medical applications of radioactivity in radiology, medical imaging like PET and MRI are taken for granted. Geology has gained enormously due to the radiometric analysis of rocks, meteorites etc.; to define a reliable geological clock would be impossible without nuclear studies. The study makes it possible to monitor climate change and analyse sources of green house gases etc. Nuclear power has great potential in mitigating the effects of climate change by replacing fossil fuels.
But the greatest benefit of nuclear studies comes about by the development of new technology. The need to handle large amounts of data and service the communication requirements of large groups spread around the globe engendered the development of the World Wide Web and the Internet. Big advances in electronics, data processing and computer technology happened because nuclear studies demanded such capabilities.
For good reason, a nucleus is called the most versatile laboratory available. It exhibits such large and varied science that many theories, which will be difficult to test otherwise, can be checked. Predictions of Einstein's theory of special and also of general relativity were tested in nuclear physics labs.
The nucleus is a tiny entity - 100,000 times smaller than an atom and everything that happens inside a nucleus requires quantum mechanics and relativistic theories for their description. To complicate matters, most nuclei are complex many body systems. It is a challenge to study and understand what happens in a nucleus.
In this course, I have restricted myself to the study of the nucleus where protons and neutrons are treated as fundamental particles. They do have structure - they are made of three quarks - but that is the subject of another course.
The course was given in Glasgow in 2008. Not much has changed in nuclear physics since then - so almost everything is up to date. The course is meant for general public without serious science background and is eminently suited for school pupils, communities and first year university students.
The talks are organised as follows:
Talk 1: Introduction, Discovery, Properties
Talk 2: Radioactivity, Discovery, Nuclear Decay Modes, Applications of Radioactivity
Talk 3: Nuclear Force, Binding Energies, Fission and Fusion
Talk 4: Nuclear Power, Atomic and Hydrogen Bombs
Blog Contents - Who am I?
The nucleus of an atom is a fascinating object - in day to day life, we are not aware of its existence. But what goes on inside a nucleus has far reaching implications. The world around us works in an electron Volt (eV) regime. (In a 1.5 Volt battery, an electron gains an energy of 1.5 eV in going between the negative and positive elctrodes). All chemical, biological and optical processes operate in the eV energy regime. Nuclear processes operate in the MeV (million electron Volt) regime - energies involved are much much higher - researchers had to develop a lot of new instrumentation and methods to study the nucleus.
The study has been rewarding bestowing great benefits to our society. Medical applications of radioactivity in radiology, medical imaging like PET and MRI are taken for granted. Geology has gained enormously due to the radiometric analysis of rocks, meteorites etc.; to define a reliable geological clock would be impossible without nuclear studies. The study makes it possible to monitor climate change and analyse sources of green house gases etc. Nuclear power has great potential in mitigating the effects of climate change by replacing fossil fuels.
But the greatest benefit of nuclear studies comes about by the development of new technology. The need to handle large amounts of data and service the communication requirements of large groups spread around the globe engendered the development of the World Wide Web and the Internet. Big advances in electronics, data processing and computer technology happened because nuclear studies demanded such capabilities.
For good reason, a nucleus is called the most versatile laboratory available. It exhibits such large and varied science that many theories, which will be difficult to test otherwise, can be checked. Predictions of Einstein's theory of special and also of general relativity were tested in nuclear physics labs.
The nucleus is a tiny entity - 100,000 times smaller than an atom and everything that happens inside a nucleus requires quantum mechanics and relativistic theories for their description. To complicate matters, most nuclei are complex many body systems. It is a challenge to study and understand what happens in a nucleus.
In this course, I have restricted myself to the study of the nucleus where protons and neutrons are treated as fundamental particles. They do have structure - they are made of three quarks - but that is the subject of another course.
The course was given in Glasgow in 2008. Not much has changed in nuclear physics since then - so almost everything is up to date. The course is meant for general public without serious science background and is eminently suited for school pupils, communities and first year university students.
The talks are organised as follows:
Talk 1: Introduction, Discovery, Properties
Talk 2: Radioactivity, Discovery, Nuclear Decay Modes, Applications of Radioactivity
Talk 3: Nuclear Force, Binding Energies, Fission and Fusion
Talk 4: Nuclear Power, Atomic and Hydrogen Bombs
Blog Contents - Who am I?
Saturday, 8 August 2015
The Sugar Debate – Confusing and Unhelpful Developments
I was
surprised by the news of the mooted official recommendation that we should reduce
our sugar intake by a factor of two – consume no more than 25g sugar, added andnaturally occurring, per day. Presumably
this is to control the obesity epidemic and tooth decay.
I have seen and heard many silly things in my life but this advice, if true, is
definitely the most outrageous for its effect on destabilising the general
public. The reasons are not difficult to
understand and that is why I find it amazing that experts, who should know
better, are failing to comprehend the science and psychology of eating and how
people react to lifestyle changes.
I have been involved in scientific research for
more than half a century and I cannot understand the sense of reducing sugar
consumption by 50%. May be the experts
know something that is not easy to reach and understand but then I am used to
delving into latent information in data and I can’t find much to go on – I am
confused. How will an average person
understand this advice is beyond comprehension?
The current guidelines are 50g (10% of recommended energy intake) per day. For my lifestyle – most meals are cooked at home from fresh ingredients, we drink water with most meals, no sugar in tea and coffee – we are just about there in sticking to the limit. Most fruits bring in 10g naturally occurring sugar and with five fruits a day, it is already 50g with no margin left. Reducing intake of sugar to 25g will require a drastic change in the eating habits and associated lifestyle changes. Nobody likes changes in the way they do things – it causes stress, headache – might induce trauma, can make you feel depressed, can give you skin problems and whatever else. This recommendation is prescribing all of these malaise to the whole nation.
As any nutritionist will tell you that the following equation holds (over long term):
The current guidelines are 50g (10% of recommended energy intake) per day. For my lifestyle – most meals are cooked at home from fresh ingredients, we drink water with most meals, no sugar in tea and coffee – we are just about there in sticking to the limit. Most fruits bring in 10g naturally occurring sugar and with five fruits a day, it is already 50g with no margin left. Reducing intake of sugar to 25g will require a drastic change in the eating habits and associated lifestyle changes. Nobody likes changes in the way they do things – it causes stress, headache – might induce trauma, can make you feel depressed, can give you skin problems and whatever else. This recommendation is prescribing all of these malaise to the whole nation.
As any nutritionist will tell you that the following equation holds (over long term):
Energy in – Energy used = Change in Weight
If you
eat too much and do not burn it by some activity then you will gain weight and vice versa. It does not really matter in what form the
energy intake is (fat, carbohydrate or protein), the body will eventually obey
the equation.
Most carbohydrate is converted to some type of sugar as a first step in digesting the food and the recommendation for daily carbohydrate consumption is about 250g. We all eat foods like potatoes, bread, rice that are rich in starch (carbohydrates). Let us take a quick look how these foods affect the body when we eat them.
The first step in digesting the food is to break down the complex carb molecules to simpler glucose molecules and this already starts when you are chewing the food. Starch is converted to glucose (a type of sugar readily absorbed by the body). Glucose molecules go into the blood stream and are responsible for increasing the blood glucose level for a short time until insulin released by the body metabolizes it to produce energy. If you are diabetic, insulin might be in short supply or ineffective, and the blood sugar level stays high for longer. You need medication to help the metabolic process.
The longer blood sugar levels stay high the greater are your chances to become diabetic in due course. If the food you eat spikes the blood sugar level higher then it will take longer to return to normal and it is considered bad for your health. They actually have a measure of the spike – the Glycemic Index (GI) which is used as a predictor of a carbohydrate’s effect on blood glucose. GI of a food is a number measured relative equal weight of glucose in their ability to increase blood sugar level.
Glucose has a GI of 100. Some other carbohydrates have GI as follows:
Most carbohydrate is converted to some type of sugar as a first step in digesting the food and the recommendation for daily carbohydrate consumption is about 250g. We all eat foods like potatoes, bread, rice that are rich in starch (carbohydrates). Let us take a quick look how these foods affect the body when we eat them.
The first step in digesting the food is to break down the complex carb molecules to simpler glucose molecules and this already starts when you are chewing the food. Starch is converted to glucose (a type of sugar readily absorbed by the body). Glucose molecules go into the blood stream and are responsible for increasing the blood glucose level for a short time until insulin released by the body metabolizes it to produce energy. If you are diabetic, insulin might be in short supply or ineffective, and the blood sugar level stays high for longer. You need medication to help the metabolic process.
The longer blood sugar levels stay high the greater are your chances to become diabetic in due course. If the food you eat spikes the blood sugar level higher then it will take longer to return to normal and it is considered bad for your health. They actually have a measure of the spike – the Glycemic Index (GI) which is used as a predictor of a carbohydrate’s effect on blood glucose. GI of a food is a number measured relative equal weight of glucose in their ability to increase blood sugar level.
Glucose has a GI of 100. Some other carbohydrates have GI as follows:
Sugar 68; White Bread 70; Baked Potato 85; White
Rice 64 etc.
The more important number is Glycemic Load (GL) which is how an average portion of the particular food will affect your blood glucose level.
The more important number is Glycemic Load (GL) which is how an average portion of the particular food will affect your blood glucose level.
This is listed in
the table below http://nutritiondata.self.com/topics/glycemic-index
Glycemic Indexes and
Glycemic Loads for Common Foods
GI and GL for Common Foods
|
||||
Food
|
GI
|
Serving Size
|
Net Carbs
|
GL
|
Peanuts
|
14
|
4
oz (113g)
|
15
|
2
|
Bean
sprouts
|
25
|
1
cup (104g)
|
4
|
1
|
Grapefruit
|
25
|
1/2
large (166g)
|
11
|
3
|
Pizza
|
30
|
2
slices (260g)
|
42
|
13
|
Low fat
yogurt
|
33
|
1
cup (245g)
|
47
|
16
|
Apples
|
38
|
1
medium (138g)
|
16
|
6
|
Spaghetti
|
42
|
1
cup (140g)
|
38
|
16
|
Carrots
|
47
|
1
large (72g)
|
5
|
2
|
Oranges
|
48
|
1
medium (131g)
|
12
|
6
|
Bananas
|
52
|
1
large (136g)
|
27
|
14
|
Potato
chips
|
54
|
4
oz (114g)
|
55
|
30
|
Snickers
Bar
|
55
|
1
bar (113g)
|
64
|
35
|
Brown
rice
|
55
|
1
cup (195g)
|
42
|
23
|
Honey
|
55
|
1
tbsp (21g)
|
17
|
9
|
Oatmeal
|
58
|
1
cup (234g)
|
21
|
12
|
Ice
cream
|
61
|
1
cup (72g)
|
16
|
10
|
Macaroni
and cheese
|
64
|
1
serving (166g)
|
47
|
30
|
Raisins
|
64
|
1
small box (43g)
|
32
|
20
|
White
rice
|
64
|
1
cup (186g)
|
52
|
33
|
Sugar
(sucrose)
|
68
|
1
tbsp (12g)
|
12
|
8
|
White
bread
|
70
|
1
slice (30g)
|
14
|
10
|
Watermelon
|
72
|
1
cup (154g)
|
11
|
8
|
Popcorn
|
72
|
2
cups (16g)
|
10
|
7
|
Baked
potato
|
85
|
1
medium (173g)
|
33
|
28
|
Glucose
|
100
|
(50g)
|
50
|
50
|
Glycemic Index (GI) and Glycemic Load (GL) for a few common foods.
GI of 55 or below are considered low; 70 or above are considered high.
GL of 10 or below are considered low; 20 or above are considered high.
GI of 55 or below are considered low; 70 or above are considered high.
GL of 10 or below are considered low; 20 or above are considered high.
One can’t help to
notice that sugar is not very important in spiking the blood glucose level while
potato and rice based dishes are the most effective.
The question is - why target sugar intake when everything
else is as important, if not more so?
I have not talked
about other possible actors that might be responsible for increase in obesity
in developed countries (may be subject of another blog). Things like our sedentary lifestyle – we are
not as active now as we used to be thirty or forty years ago. Children, in particular do not play outside
much and sit in front of TV etc. Then
the modern lifestyle creates more stress – lot of people deal with stress by
eating more and the equation tells us that they will gain weight.
I have said my bit –
let me know your thoughts about this very important matter.
Blog Contents - Who am I?
Blog Contents - Who am I?
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