Starmind.com

Frage über Abgrenzung Leben und Tod

Mon, 11 May 2009 01:11:49 +0200

"Organisches Leben wie wir es kennen, lässt sich grundsätzlich über drei Kriterien definieren: Stoffwechsel, Wachstum und Fortpflanzung.

Der Tod/tote Materie auf der anderen Seite des Spektrums sollte sich also logischerweise durch die Absenz derselben umschreiben lassen. Es ist nun aber eine seit langem bekannte Tatsache, dass dies nur in beschränktem Umfang wirklich zutrifft.

So gibt es doch das Bsp. erst kürzlich verstorbener Menschen, bei denen aber bis zu mehreren Stunden nach eintreten des Todes gewisse Zellverbände nach den oben genannten Kriterien zweifellos als lebend angesehne werden müssen. Wie ergibt sich ein solcher Sachverhalt ohne dass man die obigen lebensdefinierenden Kriterien als ungültig erklären müsste? Was ist eigentlich die definitive Grenze zwischen Leben und Tod? Gibt es diese überhaupt?
Zumal es hierbei um länderspezifische Definitionen vermutlich geht, würden wir uns auf eine Beschränkung auf Europäische Länder freuen, bevorzugt Schweiz oder und England. "

Consciousness: State of the Art?

Mon, 11 May 2009 01:11:49 +0200

We are looking for qualified inputs on latest theories derived from either neurosciences, psychology, philosophy or any other sciences on the phenomenon of consciousness. While still controversial, many theories are debated while it is difficult to keep pace with latest decvelopments. We are looking for scientifically traceable and principally provable theories on consciousness (source or content or abstract sufficient!) which are new to us or very promising. Plausability as well as scientific relevance and quality of foundations shall decide on which question solver to award our financial incentive.

Zellteilung und Hayflick Zahl: Inwiefern hängt die maximale Anzahl Zellteilungen eines Organs/Organismus mit dessen Lebenserwartung zusammen?

Mon, 11 May 2009 01:11:50 +0200

Die Hayflick Zahl definiert die Anzahl Zellteilungen einer Zelle. Danach stellen sich die Teilungen ein und die Zelle stirbt: Mehr dazu hier: http://en.wikipedia.org/wiki/Hayflick_limit

In diversen Berichten lese ich, dass das sog. Hayflick Limit je nach Organismus variert. Inwiefern hängt die Lebenserwartung mit der Hayflick Zahl zusammen?

Über eine Quellenangabe oder Angaben zu dieser Frage freute ich mich. Hast Du eine gute Antwort hierauf?

Should we improve our genome? Ethical question

Mon, 11 May 2009 01:11:49 +0200

"In a recent article in NY times: http://www.nytimes.com/2003/11/11/science/11GENO.html?ex=1212120000&en=62e31f358a5d279d&ei=5070"" I found the following statement:
""One day, people may view sex as essentially recreational, and conception as something best done in the laboratory,"" Dr. Gregory Stock wrote recently in ""Redesigning Humans. "" Parents may start to believe it is ""reckless and primitive to conceive a child without prior genetic testing.""
this contrasts with the following statement, derived from the same article: ""we risk turning the human population into one giant clone, tedious to meet with and bereft of the variation needed to respond to changing environments. The pursuit of perfection, if carried to extremes, is a sure recipe for extinction.""

Yet, from an individual's viewpoint, why should the individuum care what happens to the entire population in the very long run? It may be the same as driving with cars: Cars destroy our environment in the very long run, yet may impact is so minute that I do not fear killing my children by driving the car. Hence my question: Why should an individual not improve the genome of his offspring?
I seek for clear-cut evidence against eugenetics. The reward is issued to the most interesting and promising arguments referring to the article cited. (see PDF in the attachment)

"

Manifest against free will - find an error in the following argumentation

Mon, 11 May 2009 01:11:49 +0200

"Wanted is an error in the following argumentation against the free will: Please find a logical error or an assumption or anything how you could defend the free will without referring to something divine nor irrational not graspable to human beings. What is wrong in the following statement:
*Manifest against the free will: *

We define ""free"" as something that is not determined by another cause. As am example, a stone lifted up and then released is not considered ""free"" as it is bound to gravity. Or: A human sensation such as hunger is not considered to be caused by free will as human physiology triggers that sensation depending on the nutrition level of the body and other factors. Thence the following is true: The impression or sensation of ""free will"" is generated by the neural substrate in the human brain. As any neural repsonse or firing or activity pattern, neural responses depend on genetic factors, circuitry and electrical signal processing and on external and internal stimuli -however, neurons do not fire at a free will or at their own discretion. Any sensation is caused by an external/ internal event OR may be randomly generated (however this may work). In both cases, there is no free or intended will as it is completely determined by the underlying neural substrate, which is again completely determined by physical forces and the actio=reaction paradigm.
Any argument in disfavor of above mentioned argumentation? "

Challenging a smart argument on the existence of God

Mon, 11 May 2009 01:11:49 +0200

"I am an atheist. Yet only recently I was struk by a very clever explanation on the existence of God: It went as follows:
We have the sensation of feeling hungry or thirsty, thence we may argue that humans do only experience sensations of things that actually exist, otherwise this sensation would not make sense, or it would actually only frustrate the person. Moreover, such sensations are triggered by dedicated structured in the human brain (eg hunger, thirst, anger etc). It is interesting enought that most humans long for eternal live, long for paradise and a fair instance such as God. The fact that something like the ""hunger for God exists"" as does the ""hunger for food"" exist, may be equated to the fact that food exists. Hence there must be a God.
Question: How could this argument be challenged? "

The essentials of Spike timing dependent plasticity (STDP) - how can STDP render an Artificial Neural Network time sensitive? Easy explanation sought!

Mon, 11 May 2009 01:11:52 +0200

Artificial neural networks (ANN) become more and more sophisticated. Among them, spiking ANN to me seem very interesting.
An interesting algorithm is the so called "Spike Timing Dependent Plasticity", nicely detailed in
Synaptic plasticity: taming the beast. by: LF Abbott, SB Nelson Nat Neurosci, Vol. 3 Suppl (November 2000), pp. 1178-1183., see attachment.

To me the concept of STDP is somewhat cloudy, meaning, I do not understand how STDP may render an ANN sensitive for timely orchestrated events.
Of course, there are papers about that topic, yet to me an easy to understand simple explanation is still lacking. Any help here is highly appreciated:

How can overall an ANN become sensitive to timely orchestrated events just by executing the STDP rule?
Thank you very much!

Visual nerve paradox - how can it be that 1 Mio nerve fibers provide sufficient visual information to the brain?

Mon, 11 May 2009 01:11:52 +0200

I have learnt that the human visual nerve contains roughly 1 Mio nerve fibers. GIven an maximum spike frequency of eg 100 HZ (the average is rather below 30 HZ) one eye could hence convey 30 x 1 Mio = ~30Mbit /sec information, or about 4 Mbyte (or 12Mbyte) assuming that one spike is viewed as a 0 or 1.

In any case, to me that looks a rather low number and hence a pretty low information content.

There are theories, that the shape of spikes may contain information as well, however, to me action potentials seem like all or nothing answers. Also, time coding may convey information, however, this concept I do not really understand.

For a class work to be handed in, I would be grateful if you provided me with hints I could resolved that dillemma. Thank you very much!

Solving the famous homunculus problem: Is there a small intelligent unit within our brain?

Mon, 11 May 2009 01:11:52 +0200

Often, people think that all the information sensed by our sensors eg in the hand, eyes, nose etc need to be somehow integrated within eg the human brain. Through numerous nerve fibers the sensed signals/stimuli ultimately lead to the brain where something is "integrated" , "analyzed" etc.

To depict that poblem, a homunculus (small smart human) could be assumed sitting in our brain receiving all that information (see attachment). The homunculus then receives eg input such as "green!", "tall", "has leaves", "contains a wooden basis", "smells like a tree" so that the homunculus decides then -> "that is a tree!". The human then recognizes that the various stimuli sensed by the environment were integrated so as to build up the sensation of a "tree".

Of course, that assumption has no scientific basis and it just shifts the problem down one level - how does the homunculus cope with that problem?

Only recently a professor mentioned to me, that maybe the brain does not need to integrate the information. How then still, can the brain integrate all those various sensory inputs so as to come up with the sensation of a tree? The so called "binding problem" seems to be related:
http://en.wikipedia.org/wiki/Binding_problem

(I do not so much belibe in synchronizity as this explanation also just shifts the problem)

The question remains to me : do you have any creative and maybe novel concept on how I can avoid a homuncukus sitting in a brain and integratinig the incoming information?

I reward any smart and useful concept! Thanks a lot!

Griechische Mythologie: Wer beeinflusst die 3 Parzen?

Mon, 11 May 2009 01:11:53 +0200

Die 3 Parzen: http://de.wikipedia.org/wiki/Parzen sind gemäss Mythologie die Weberinnen der Schicksale.
Ich frage mich, wer die 3 Parzen beeinflusst.

Gibt es dazu Indizien aus der Mythologie?

Looking for 3D data showing the burrowing process of bivalves.

Mon, 11 May 2009 01:11:53 +0200

In order to investigate the burrowing process of bivalves, I would like to have 3D data of this process (i.e. 3D positions and orientations over time, either explicitly or implicitly). Is there any source of such data, generated, e.g., by position or acceleration sensors, computed tomography (CT), ultrasonography or any other method? Of course, also good quality videos of bivalves burrowing themselves are useful, but I would prefer 3D data. The particular species is not important, it would even be great to be able to compare different species (e.g. fast/slow or shallow/deep burrowers).

Are they data that proof Sigmund Freud’s interpretation of dreams

Mon, 11 May 2009 01:11:53 +0200

What do dreams tell about people?

I’ve read Sigmund Freud’s interpretation of dreams, and honestly, it sounds pretty vague and made up to me. Do dreams actually tell us something about our feelings or unconscious desires? I would like to see some data to proof this.

How can the IQ be positively affected? What are there studies in favor or disfavor of it?

Mon, 11 May 2009 01:11:53 +0200

Can one improve one’s score on IQ-tests by practising, or is most of intelligence genetically determined? Can one improve one’s ability to memorize things, for example random numbers? How does the capacity for learning change when the person gets older? I’m looking for reliable surveys about this subject that show to what extent one can improve one’s ‘intelligence’ through practice, and how this depends on the age of the person.

A theory to challenge: Neural Networks (Brain Cells) are just a further development (or higher level) of genetic regulatory networks - what is your opinion here?