In the decision to clear Macchiarini of misconduct (Swedish text), Karolinska states that the decision to operate on the first patient had been taken "after a clear process in health care including an evaluation by the ethics council of Karolinska Hospital". Macchiarini describes this process in...
Macchiarini operated in violation of the Nuremberg Code and of the Declaration of Helsinki, principles of ethics for medical experiments on humans that were written down as a reaction to what had become known in the doctors' trials after WWII.
But in this case, the record was not corrected from within science. Ethics committees gave the ok to Mengele-type experiments. Scientific peers (people in Italy, Delaere, colleagues at KI) tried to sound the alarm about discrepancies, there was an investigation, Gerdin reached clear conclusions...
He may have access to a stash of lab reports by older students? That was what I had, way way back. (I never copied though, just used them to learn.)
It is not uncommon to find plagiarism in introduction and background. I react strongly in such cases, the student is in trouble when I see that...
Thanks for reopening the thread. A very good summary by Gretchen Vogel was published in Science February 4.
Since then the secretary general of the Nobel committee has resigned, because he assumed that he would be investigated by a special inquiry. That inquiry will be headed by Sten Heckscher...
The whole system: peer review, collegiality, institutional checks and balances, ethics approval, science journalism, investigations into scientific misconduct.
None of this worked.
Extraordinary claims got published without even ordinary evidence.
Maybe you saw the piece about this star surgeon's personal life in Vanity Fair, mythomaniac lies about getting married by the Pope, Putin and the Obamas attending. If it is too good to be true, it probably ain't true.
The guy has a base in Sweden, at Karolinska Institutet, the home of the Nobel...
As you suspected, I suppose.
You can check your answers yourself: if you put back "t=20.81" in the first line of your equation, you will see that you are way off.
From your second line, one can see that cooling and heating have a ratio of about 2:1 in temperature.
It is not so easy to be creative for exams, retakes, and re-retakes on a number of courses each year. And it is bad for throughput.
I want to teach, give my students the opportunity to learn something. I do not want to be police. I have reported egregious cases of cheating to the board of...
If you look at the Earth's field as produced by a current loop, you are looking on a scale where the field is inhomogeneous. Then there is a force between the two. But a current loop cannot produce a homogeneous field.
(It may also help to remember that the gravitational attraction from an...
On the scale of the compass, the Earth's field is homogeneous. It only exerts a torque on the compass, otherwise there is no force between the two.
(I am not entirely sure if this is relevant as an answer.)
Units don't matter, just use the ratio.
It is quite a difference if the mass is oscillating up and down on a string or whether the string is in a transverse oscillation without the mass moving. Different kinds of motion, different formulas apply.
Or you could start looking at molecules, for example the energy levels of the H2 molecule. Then think about the energy levels of electrons in lithium clusters with increasing numbers of atoms. This leads to the tight-binding approximation of solids.
You can probably figure out how to obtain the resistance between opposite corners when all edges of the cube have equal resistance, but how would you do the general cube?
Other examples are messy nets of resistors, current sources, and voltage sources.
Of course the photoelectric current must depend on the color of the light. X-rays go straight through.
Here is a plot of the spectral response of some alkali photocathodes (note the logarithmic scale):
The best these optimized...
There is also this way:
It uses the gamma photons from...
The material with the largest band gap is lithium fluoride, LiF, about 11 eV. Beyond that, everything absorbs any vacuum-UV or x-ray. If you need windows, people use thin foils of low-Z elements like beryllium or boron nitride or carbon.
Avoid calculating with numbers that are so large or small that you do not have any intuition for it.
The basic number to remember is the gas constant, 8.3 joule per mole per kelvin. That way you can be more confident about your answer.
You are asking now not about x-rays, but about visible light. Then the band gap is important. Graphite does not have a band gap and is therefor opaque. Diamond has a large band gap and is transparent for visible light.
Metals are usually crystalline. It is difficult to make amorphous metals (metglass). They are not thermodynamically stable.
None of this matters for the x-ray attenuation length, unless one looks at minute details.
Nuclear motion does not matter at all for X-ray absorption. It is an atomic property. Band gaps only matter when one is doing high-resolution near-edge spectroscopy. Also melting only has an effect on minor details.
Lamps usually have a sticker saying the maximum allowed wattage. If you use bulbs with more power, you risk fire etc.
I guess that you used a halogen light bulb. Those need to be handled with care, the glass surface must not have fingerprints.