is an excellent book by Paul Nurse (isbn 978-1-788451-40-6) As usual
I'm going to quote from a few pages.
Cells repair these mutations, but they are not
completely successful. If they were, all individuals
of a species would be identical and evolution would stop.
This means the error rate itself is subject to natural selection.
If that error rate is too high the information stored by the genome
will degenerate and become meaningless, and if errors are too rare,
the possibility for evolutionary change is reduced.
Over the long term, the most successful species will be those that can maintain
the right balance between constancy and change.
Humanity should care about the entire biosphere; all the different
life forms that share our planet are our relatives.
Once microbes evolved the ability to photosynthesize, they
multiplied, over the millenia, to such an extent that the amount
of oxygen in the atmosphere spiked. What followed, between 2
and 2.4 billion years ago, is called the Great Oxygen
Catastrophe. All organisms that existed at that time were
microbes, either bacteria or archaea, but some researchers
think most of them were wiped out by the appearance
of all that oxygen. It is ironic that life created conditions
that nearly ended life as a whole.
To fuel all of the chemical reactions needed to support your
body's trillions of cells, your mitochondria together produce,
amazingly, the equivalent of your entire bodyweight in ATP every day!
The life forms that survive natural selection persist because they
work, not necessarily because they do things in the most
efficient or straightforward way possible. ... This can disturb
some physicists who turn their attentions to biology. Physicists
tend to be attracted to elegant, simple solutions, and can be less comfortable with the messy and less-than-perfect reality of
living systems.
Even plants rely on bacteria found in or near their roots that
capture nitrogen from the atmosphere. ... In fact, this is something that,
as far as we know, no eukaryote can do for itself. That means there is
not a single known species of animal, plant or fungus that can generate
its own cellular chemistry entirely from scratch.
Life on Earth belongs to a single, vastly interconnected ecosystem,
which incorporates all living organisms.
Biology shows us that all the living organisms we know of are related
and closely interacting. We are bound by a deep connectedness
to all other life.
is an excellent book by Yuval Noah Harari (isbn 978-0-099-59008-8) As usual
I'm going to quote from a few pages.
Whereas chimpanzees spend five hours a day chewing raw food, a single
hour suffices for people eating cooked food.
Since long intestines and large brains are both massive energy consumers,
it's hard to have both. By shortening the intestines and decreasing their
energy consumption, cooking inadvertently opened the way to the jumbo
brains of Neanderthals and Sapiens.
Large numbers of strangers can cooperate successfully by believing in
common myths.
There is some evidence that the size of the average Sapiens brain has actually
decreased since the age of foraging. Survival in that era required superb mental
abilities from everyone.
What characterises all these acts of communication is that the entities being addressed are local beings. They are not universal gods, but rather a particular
deer, a particular tree, a particular stream, a particular ghost.
The extra food did not translate into a better diet or more leisure.
Rather, it translated into population explosions and pampered elites.
The new agricultural tasks demanded so much time
that people were forced
to settle permanently next to their wheat fields.
This is the essence of the Agricultural Revolution: the ability to keep more
people alive under worse conditions.
One of history's few iron laws is that luxuries tend to become necessities and to
spawn new obligations.
Evolution is based on difference, not on equality.
There is not a single organ in the human body that only does the job its prototype
did when it first appeared hundreds of millions of years ago.
The mere fact that Mediterranean people believed in gold would cause Indians to
start believing in it as well. Even if Indians still had no real use for gold,
the fact that Mediterranean people wanted it would be enough to make the Indians
value it.
The first religious effect of the Agricultural Revolution was to turn plants
and animals from equal members of a spiritual round table into property.
The monotheist religions expelled the gods through the front door with a lot
of fanfare, only to take them back in through the side window. Christianity,
for example, developed its own pantheon of saints, whose cults differed
little from those of the polytheistic gods.
Level two chaos is chaos that reacts to predictions about it, and therefore
can never be predicted accurately.
In many societies, more people are in danger of dying from obesity than
from starvation.
Each year the US population spends more money on diets than the amount
needed to feed all the hungry people in the rest of the world.
Throughout history, the upper classes always claimed to be smarter, stronger
and generally better than the underclasses... With the help of new medical
capabilities, the pretensions of the upper classes might soon become an
objective reality.
is an excellent book by Daniel Coyle (isbn 978-1-847-94127-5) As usual
I'm going to quote from a few pages.
Much of the connection happens around the dinner table,
as Popovich is obsessed with food and wine.
One misconception about highly successful cultures
is that they are happy, lighthearted places. This is mostly not
the case. They are energized and engaged, but at their core
their members are oriented less around achieving happiness
than around solving hard problems together.
Allen could find none that played a meaningful role in
cohesion. Except for one. The distance between their desks.
For the vast majority of human history, sustained proximity
has been an indicator of belonging.
It's important to avoid interruptions. The smoothness of turn
taking, as we've seen, is a powerful indicator of cohesive
group performance.
The groups I studied had extremely low tolerance for bad apple behaviour.
The groups I visited were uniformly obsessed with design as a lever
for cohesion and interaction.
He also had the company buy nicer coffee machines and install them
in more convenient gathering places.
Merely replacing four-person tables with ten-person tables has
boosted productivity by 10 percent.
Kauffman decreed that every aspect of training be team-based.
It's very hard to be empathic when you're talking.
The road to success is paved with mistakes well handled.
We should have made the hallways wider. We should have made the cafe bigger.
is an excellent book by Douglas Adams (isbn 978-0-330-49120-4).
As usual
I'm going to quote from a few pages.
He would insult the universe. That is, he would insult
everybody in it. Individually, personally, one by one,
and (this was the thing that he really decided to grit his teeth over)
in alphabetical order.
'Eddies,' said Ford, 'in the space-time continuum.'
'Ah, nodded Arthur, 'is he? Is he?'
It was a charming and delightful day at Lord's as
Ford and Arthur tumbled haphazardly out of a space-time
anomaly and the immaculate turf rather hard.
'A what?' he said.
'An SEP.'
'An S...?'
'...EP.'
'And what's that?'
'Somebody Else's Problem,' said Ford.
The second non-absolute number is the given time of arrival,
which is now known to be one those most bizarre of concepts,
a recipriversexcluson, a number whose existence can only
be defined as being anything other than itself. In other words,
the given time of arrival is the one moment of time at which
it is impossible that any member of the party will arrive.
'Tell me it was a coincidence, Dent' it said. 'I dare you
to tell me it was a coincidence!'
'It was a coincidence,' said Arthur quickly.
It was the Cathedral of Hate.
It was the product of a min that was not merely twisted,
but actually sprained.
It was huge. It was horrific.
It had a Statue in it.
We will come to the Statue in a moment.
'I got yanked involuntarily back into the physical word,'
pursued Agrajag, 'as a bunch of petunias. In, I might add, a bowl.'
Strictly speaking, all editors since Lig Lury Jr have therefore
been designated Acting Editors, and Lig's desk is still
preserved the way he left it, with the addition of a small sign
which says 'Lig Lury Jr, Editor, Missing, presumed Fed'.
The longest and most destructive party ever held is now into its
fourth generation and still no one shows any signs of leaving.
is an excellent book by Douglas Adams (isbn 978-0-330-49121-1).
As usual
I'm going to quote from a few pages.
There is another theory which states that this has already happened.
The story so far: In the beginning the Universe was created.
This had made a lot of people very angry and been widely regarded
as a bad move.
The motto stands - or rather stood - in three-mile high illuminated
letters near the Complaints Department spaceport on Eadraz.
Unfortunately its weight was such that shortly after it was erected,
the ground beneath the letters caved in and they dropped for nearly
half their length through the offices of many talented young
complaints executives - now deceased.
Quite how Zaphod Bebblebrox arrived at the idea of holding a
seance at this point is something he was never quite clear on.
'Listen, three eyes,' he said', 'don't you try to outweird me,
I get stranger things than you free with my breakfast cereal.'
Marvin was forced to say something which came very hard to him.
'I don't know,' he said.
'I go up,' said the elevator, 'or down.'
'Good,' said Zaphod. 'We're going up.'
'Or down,' the elevator reminded him.
And the worse they were to wear, the more people had to buy to
keep themselves shod, and the more the shops poliferated,
until the whole economy of the place passed what I believe is
termed the Shoe Event Horizon, and it became no longer economically
possible to build anything other than shoe shops.
'Transtellar Cruise Lines would like to apologize to passengers
for the continuing delay to this flight. We are currently
awaiting the loading of our complement of small lemon-soaked
napkins for your comfort, refreshment and hygiene during the
journey. Meanwhile we thank you for your patience.'
In it, guests take (willan on-take) their places at table
and eat (willan on-eat) sumptuous meals whilst watching
(willing watchen) the whole of creation explode around them.
'You've never heard of Disaster Area?'
'It says "Golgafrinchan Ark Fleet, Ship B, Hold Seven,
Telephone Sanitizer Second Class" - and a serial number.'
To summarize the summary: anyone who is capable of getting
themselves made President should on no account be allowed
to do the job.
Their track suits were now all dirty and even torn, but they
all had immaculately styled hair.
is an excellent book by Douglas Adams (isbn 978-0-330-49119-8).
As usual
I'm going to quote from a few pages.
Far out in the uncharted backwaters of the unfashionable
end of the Western Spiral Arm of the Galaxy lies a small
unregarded yellow sun.
The Guide also tells you on which planets the best Pan
Galactic Gargle Blasters are mixed, how much you can
expect to pay for one and what voluntary organizations
exist to help you rehabilitate afterwards.
People of Earth, your attention please.
This is Prostetnic Vogon Jeltz of the Galactic Hyperspace
Planning Council...
The practical upshot of all this is that if you stick a Babel fish in
your ear you can instantly understand anything said to you in any
form of language.
The prisoners sat in the Poetry Appreciation chars - strapped in.
'Space', it says, 'is big. Really big. You just won't believe how
vastly hugely mindbogglingly big it is. I mean you may think it's
a long way down the road to the chemist, but that's just peanuts to
space. Listen...' and so on.
The principle of generating small amounts of finite improbability
by simply hooking the logic circuits of a Bambleweeny 57
Sub-Meson Brain to an atomic vector plotter suspended in a strong
Brownian Motion producer (say a nice hot cup of tea) were of
course well understood.
Here I am, brain the size of a planet and they ask me to take you
down to the bridge. Call that job satisfaction? Cos I don't.
For years radios had been operated by means of pressing buttons
and turning dials; then as technology became more sophisticated
the controls were made touch sensitive - you merely had to brush
the panels with your fingers; now all you had to do was wave your
hand in the general direction of the components and hope. It saved
a lot muscular expenditure of course, but meant that you had to sit
infuriatingly still if you wanted to keep listening to the same
programme.
'Oh God,' said Zaphod. He hadn't worked with this computer for
long but had already learned to loathe it.
'Computer!' shouted Zaphod. 'Rotate angle of vision through
one-eighty degrees and don't talk about it!'
Many men of course became extremely rich, but this was perfectly
natural and nothing to be ashamed of because no one was
really poor - at least no one worth speaking of.
'Hi there! This is Eddie your shipboard computer, and I'm feeling
just great, guys, and I know I'm just going to get a bundle of kicks
out of any program you care to run through me.'
'You just let the machines get on with the adding up,' warned
Majikthise, 'and we'll take care of the eternal verities, thank you very much.
You want to check your legal position you do, mate. Under the law the
Quest for the Ultimate Truth is quite clearly the inalienable prerogative
of your working thinkers.'
'I think the problem, to be quite honest with you, is that you've
never actually known what the question is.'
R is a velocity measure, defined as a reasonable speed of travel
that is consistent with health, mental wellbeing and not being more than
say five minutes late.
is an excellent book by Tristan Gooley (isbn 978-1-473-61522-9).
As usual I'm going to quote from a few pages:
One of the universal truths of human observation is that we
see
more of what we expect to see and less of what we don't expect to see.
Much of my work is not about teaching people to see things that are hard to see,
but in showing them how to notice the things that hide in plain sight.
It did not take sailors long to work out that a ship that carries too much may
be vulnerable in heavy seas, but sailors were rarely the ones to make the
decision about how much cargo a ship could safely carry. The merchants making
the profit would have had a different view to the deckhand, especially if the
trader never set foot on the vessel. This led to a wrestle between greedy traders
and cautious captains that lasted centuries. The first attempts to regulate how
much a ship could carry go back over four thousand years to ancient Crete.
Samuel Plimsoll, a nineteenth-century English politician, realized that a low
freeboard height can present a problem, but he also appreciated that it becomes
the solution if we take a very keen interest in it. In other words,
we can tell if there is too much cargo in the boat by looking much more carefully
at how high the water rises up the side of the hull. And the easiest way to do
this is by drawing a ruler on the side of the ship, calibrated according to an
architect's or engineer's understanding of the boat. These lines, which became
known as Plimsoll Lines, were such a simple and brilliant success that they
became law and proliferated around the world.
From 1833, when the first tide tables were produced by the Admiralty, the
emphasis shifted from looking, thinking and understanding, to depending
on tables of others' measurements.
There is a stange truth in the profile of beaches: they have evolved in a physical
sense to be a near ideal shape to defend themselves against the onslaught of the sea.
This means that almost any attempt to engineer a 'solution' to what nature is trying
to achieve has as much chance of backfiring as working.
Many sailors use little pieces of fabric, nicknamed 'tell-tails', that are
tied to the sails and stays (the wires that give the mast stability), to offer
a constant visual
reminder of what the wind is doing.
Once the depth of the water is half the wavelength of the waves, it effectively
cramps the motion of the waves and it is this that slows them down.
Sailors dislike precision almost as much as they like
bureaucracy.
Rivers do not run straight for more than ten times their own width.
There will be an alternating combination of quick water and much slower
water and this always happens in a certain way. The quick patches are knowns,
perhaps onomatopoeically, as 'riffles' and the slower areas are known as pools.
If there is no human tinkering with a river's flow, then there will be a
riffle-pool sequence for every stretch of river that is fives times its width.
It is typical for the water at the sides of a river to be
travelling at only a quarter of the speed of the water in
the centre. The river is being slowed by two things at its sides;
when it comes into contact with banks it is slowed by friction
and it is also slowed by the shallowing at the sides.
A stream is just a river you can step over.
Swell is the name of the waves that have enough energy to
travel beyond the area of wind.
is an excellent book by Niels Pflaeging (isbn 978-0-9915376-0-0).
As usual I'm going to quote from a few pages:
What Taylor pioneered was the idea of consistently dividing an
organization
between thinking people (managers) and executing
people (workers).
Problem-solving in a life-less system is about instruction.
Problem-solving in a living system is about
communication.
Any attempt to motivate can only lead to de-motivation.
Ultimately, organizing for complexity
and self-organization are always about empowering
teams
... not about empowering individuals.
Actual teams
of people working for and with each other.
Nobody is in control. Everybody is in charge.
To be intensively involved in selection [recruiting] is a matter of honor.
A hallmark of great selection is that it is highly
time-consuming.
Management is a mindset that will not just go away all by itself.
When employees think for themselves and make entrepreneurial decisions
automonomously, you must at all times bear joint reponsibility for
those decisions, even if you or other members of the organization
might have decided differently.
A "beta" kind of organization produces many such stories: Peculiarities,
unusual practices, by which they can be instantly recognized among so
many over-managed and under-led organizations.
People do not need to be forced to work. However, this deeply-seated
prejudice about people and their relationship to work is what keeps
management alive.
is an excellent book by Miyamoto Musashi, translated by Thomas Cleary (isbn 1-57062-748-7).
As usual I'm going to quote from a few pages:
Preface: In common parlance, to do something with a real sword means to do it with utmost earnestness… The Book of Five Rings… explicitly intended to symbolise processes of struggle and mastery in all concerns and walks of life.
The martial way of life practiced by warriors is based on excelling others in anything and everything.
Fourth is the way of the artisan. In terms of the way of the carpenter, this involves skilful construction of all sorts of tools, knowing how to use each tool skilfully, drawing up plans correctly by means of the square and the ruler, making a living by diligent practice of the craft… practice unremittingly.
You should observe reflectively, with overall awareness of the large picture a well as precise attention to small details.
Having attained a principle, one detaches from the principles; thus one has spontaneous independence in the science of martial arts and naturally attains marvels.
As human beings, it is essential for each of us to cultivate and polish our individual path.
Observation and perception are two separate things.
It is essential to be relaxed in body and mind.
If you get to feeling snarled up and are making no progress, you toss your mood away and think in your heart that you are starting everything anew.
In my military science, it is essential that the physical aspect and the mental state both be simple and direct.
Whether in large- or small-scale military science, there is no narrow focus of the vision. As I have already written, by finicky narrowness of focus, you forget about bigger things and get confused, thus letting certain victory escape you.
Things stick in your mind because of being in doubt.
The practice of all the arts is for the purpose of clearing away what is on your mind. In the beginning, you do not know anything, so paradoxically you do not have any questions on your mind. Then, when you get into studies, there is something on your mind and you are obstructed by that. This makes everything difficult to do.
C has a facility for checking dynamic assertions at run-time. It's inside
<assert.h> and its called
assert. Now
assert is a macro, so why isn't it called
ASSERT? I don't know. Prior art no doubt. Anyway,
assert is a
dynamic runtime feature, you can only use it inside functions.
/* not inside a function, won't compile :-( */
assert(sizeof(int) * CHAR_BIT >= 32);
That's a pity because it would be nice if I could get the compiler to
check things like this automatically at compile time. I've occasionally seen
an attempt at a compile-time check like this...
#if sizeof(int) * CHAR_BIT < 32
#error People of Earth. Your attention please...
#endif
But this doesn't work. The C preprocessor is a glorified text reformatter:
it knows practically nothing about C. However, there is a way to write this
as a compile time assertion (and moving any error trap to an earlier phase
is a Good Thing)
What's is going on here? Well, the example preprocesses to...
char constraint[sizeof(int) * CHAR_BIT >= 32];
If the expression is true, (an int is at least 32 bits),
the expression
will have a value of one, and constraint will be an array
of one char.
If the assertion is false, (an int is less than 32 bits),
the expression
will have a value of zero, and constraint will be an
empty array. That's
illegal, and you'll get a compile time error. Viola, a compile time assertion :-)
You can use it inside and outside a function but you can't use it twice in
the same function, as you end up with a duplicate definition.
To solve that problem you could resort to some convoluted macro trickery:
But this is pretty horrible. Also, you will probably get warnings about
unused variables. Take a step back for a moment and think about why
it works at all. It's because you have to specify the size of an array as
a compile time constant. The formal grammar of a direct-declarator
tells you this. Let's look at some bits of grammar more closely:
I just piggy backed on this, using the constraint that the value of the
constant expression cannot (in this context) be zero. A natural question
(to the curious) is are there other parts of the formal grammar that
require a constant expression. The answer, of course, is yes.
Reading the constraints of a bit field I see that if the width of a bit-field
is zero the declaration cannot have a declarator. In other words this is legal...
struct x { unsigned int : 0; };
but this is not...
struct x { unsigned int bf : 0; };
This suggests another way to create a compile time assertion
#define COMPILE_TIME_ASSERT(expr) \
struct x { unsigned int bf : expr; }
COMPILE_TIME_ASSERT(sizeof(int) * CHAR_BIT >= 32);
Trying this we again get duplicate definitions, not of a variable
this time, but of the type struct x. However we can fix
this by creating an anonymous struct:
It's well known that you can't have two case labels with the
same constant. The following will not compile...
switch (0)
{
case 0:
case 0:;
}
So, here's yet another way to create a compile time assertion. This time we
don't create a dummy variable, or a dummy type, but a dummy statement. A
dummy switch statement:
If pred evaluates to true (i.e., 1) then the case
labels will be 0 and 1.
Different; Ok. If pred evaluates to false (i.e., 0) then the
case labels
will be 0 and 0. The same; Compile time error. Viola. However, a
switch
statement cannot exist in the global scope. So the last piece of the puzzle
is to put the compile time assertions inside a function.
Events declared in a class have their += and -= access automatically locked via a lock(this) to make them
thread safe (static events are locked on the typeof the class). Events declared in a struct do not
have their += and -= access automatically locked. A lock(this) for a struct would not work since you can
only lock on a reference type expression.
Exist on stack or heap?
Value type local instances are allocated on the stack.
Reference type local instances are allocated on the heap.
Can cause garbage collection?
Creating a struct instance cannot cause a garbage collection
(unless the constructor directly or indirectly creates
a reference type instance) whereas creating a reference type
instance can cause garbage collection.
Meaning of this?
In a class, this is classified as a value, and thus cannot appear on the
left hand side of an assignment, or be used as a ref/out parameter. For example:
In a struct, this is classified as an out parameter in a constructor and as a ref parameter
in all other function members. Thus it is possible to modify the entire structure by
assigning to this or passing this as a ref/out parameter. For example:
Note however that when you call a method on a readonly value-type field, the method
call is made on a copy of the field.
structDirect{// as above}classCaller{publicvoidMethod(){Console.WriteLine(d.Field);// writes 42d.Reassign(newDirect(24));Console.WriteLine(d.Field);// writes 42!}privatereadonlyDirectd=newDirect(42);}classShow{staticvoidMain(){Callerc=newCaller();c.Method();}}
Always have a default constructor?
A struct always has a built-in public default constructor.
classDefaultConstructor{staticvoidEg(){Directyes=newDirect();// always compiles okInDirectmaybe=newInDirect();// compiles if c'tor exists and is accessible//...}}
This means that a struct is always
instantiable whereas a class might not be since all its
constructors could be private.
A struct cannot have a destructor. A destructor is just
an override of object.Finalize in disguise, and structs, being value types,
are not subject to garbage collection.
.methodfamilyhidebysigvirtualinstancevoidFinalize()cilmanaged{// ...}// end of method Indirect::Finalize
Default field layout?
The default [StructLayout] attribute (which lives in the
System.Runtime.InteropServices namespace) for a struct is LayoutKind.Sequential
whereas the default StructLayout for a class is LayoutKind.Auto. (And yes,
despite its name you can tag a class with the StructLayout attribute.)
In other words the CIL for this:
You can't use the [MethodImpl(MethodImplOptions.Synchronized)] attribute
on methods of a struct type (if you call the method you get a runtime TypeLoadException) whereas you can use
the [MethodImpl(MethodImplOptions.Synchronized)] attribute on methods of a class type.
usingSystem.Runtime.CompilerServices;classIndirect{[MethodImpl(MethodImplOptions.Synchronized)]// compiles and runs okpublicvoidMethod(){//...}}structDirect{[MethodImpl(MethodImplOptions.Synchronized)]// compiles ok, runtime TypeLoadExceptionpublicvoidMethod(){//...}}
Can be pointed to?
Clause 25.2 of the C# standard defines an unmanaged type as any type that isn't
a reference type and doesn't contain reference-type fields at any level of
nesting. That is, one of the following:
Any simple value type (11.1.3, eg byte, int, long, double, bool, etc).
Any enum type.
Any pointer type.
Any user-defined struct-type that contains fields of unmanaged types only.
You can never take the address of a instance of a type that is
not unmanaged (a fixed variable 25.3).
In contrast, you can (nearly) always take the address of an unmanaged instance.
structDirect{// no reference fields at any level of nesting}classSimpleCase{staticvoidMain(){Directvariable=newDirect();unsafe{Direct*ptr=&variable;// compiles ok//... }}}
However, you have to take the address inside a fixed statement if the variable is moveable
(subject to relocation by the garbage collector, see 25.3 and example above).
Also, you can never take the address of a volatile field.
So, in summary, you can never create a pointer to a class type but you
sometimes create a pointer to a struct type.
Can be stackalloc'd?
You can only use stackalloc on unmanaged types. Hence you can never use stackalloc on
class types. For example:
Also, the definite assignment rules of a struct are tracked on an individual
field basis. This means you can bypass initialization and "assign" the fields of
a struct one a time. For example:
a struct can't call : base() in its constructor whereas a class with no
explicit base class can.
a struct can't extend another class, a class can.
a struct can't declare protected members (eg fields, nested types) a class can.
a struct can't declare abstract function members, an abstract class can.
a struct can't declare virtual function members, a class can.
a struct can't declare sealed function members, a class can.
a struct can't declare override function members, a class can.
The one exception to this rule is that a struct can override the
virtual methods of System.Object, viz, Equals(), and GetHashCode(),
and ToString().
Equals behavior?
classes inherit Object.Equals which implements identity equality
whereas structs inherit ValueType.Equals which implements value equality.
