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- Optical Constants and Thickness through Ellipsometry?
I've been reading about ellipsometry and think I understand how to measure the parameters Delta and Phi. What I'm having trouble finding is a comprehensive resource on how to infer thickness and optical constants of a film. Imagine I had a single layer film of complex index of refraction n=n+ik and thickness D. Can I use ellipsometry to identify these both of the parameters, or will one of them be tunable? For example, I can fudge with D given n and vice versa? Or are there enough constraints to predict both simultaneously?
And then what about a bilayer of n1, n2 and d1, d2? Can ellipsometry still be applied to this system?
It came along with the machine. I think you have to pay for it:
- Have duroplastic or thermoplastic material the best shielding effect of a electromagnetic field at 1 GHz ?
Have duroplastic or thermoplastic material the best shielding effect of a electromagnetic field at 1 GHz ?
Dr.Celzard is correct. Thermoplastics with short carbon fibers can be used. Either conducting carbon nanotubes or graphite fibers will work. Some compounded materials are commercially available. You could also use woven graphite cloth by impregnating it with a monomer or a crosslinking system. Since the graphite fibers are long and in contact with other fibers, this will provide the best protection. Sheets of such materials are made routinely (used in airplane wings) and may be available separately.Following
- Can some one help me in identification of SNPs in MCF10A cell line?
I am designing molecular beacons specific to MCF10A cell line.
Thank you. I wanted to find some SNPs specific to MCF10A cell line. Can you help me with little more details on how to search for the SNPs.
- Is there any database or software which I can use to predict the interaction between plant-microbe proteins?
I have purified a bacterial protein and I want to predict its possible interactors in plants. I have both accession no. and sequence of my purified protein.
Thanks a lot Noha for the valuable information...i will check the attached link.Following
- Does anyone know of any studies showing that Raw milk has more K2 than Pasteurized milk?
I did find that K2 is heat tolerant, but was wondering if there is any evidence about more K2 in Raw milk.
Dear KAthleen,pls check!
Another fat soluble vitamin not affected by
pasteurization is vitamin K
• Vitamin K is found in low concentrations in
milk (0.2 μg/100g)
Miller, G., et.al. Handbook of Dairy Foods and Nutrition. (2007). Florida: CRC Press
- Is there room for superstition in the more pragmatical, scientific mind?
I have noticed that several intelligent people can simultaneously behave in an "oversensitive" way.
On my own particular case, I had to take a step backwards, before entering the room of my PhD Viva, to be certain that I would enter with my right foot. Nevertheless, I do own a black cat and wouldn't care to avoid going out on Fridays the 13t... And might consider it foolish, when I notice that many airway companies would avoid numbering the 13th seat.
Is there room for superstition in an intelligent mind?
I think there is some confusion between superstition and the supernatural. Edgar Allen Poe' stories are gothic horror/supernatural, not superstition. The supernatural entails belief in ghosts, spirits, demons, mysterious forces, unexplained events, etc. There is no room for the supernatural in the intelligent mind, unless, of course, one is an intelligent Wiccan or Satanist, but I'm not sure intelligence is an attribute that can be applied to such groups.
When we say we "believe in superstition" the word "believe" does not have the same value as in the case of strongly held religious beliefs. It might be better to say that we react unconsciously and spontaneously to superstitions than that we believe in them. Our reactions to superstitions are social conventions and customs gained over a lifetime of social and psychological conditioning. They are no different than patting someone on the back for a job well done, saying "bless you" when someone sneezes, saying "break a leg" to someone about to go on stage. These reflex reactions are conditioned behavior and they are trivial and inconsequential.
Superstitions and our reactions to them can exist in the intelligent mind without diminishing intelligence in the slightest.
Of course, that's just my opinion and I'm stickin' to it! I just knocked on wood about that statement and I felt .75% of my intelligence slipping away.
It might be interesting to consider if superstitions are universal. Are there superstitions that are unique to your country?
Best regards and thanks to Maria for an interesting question!
- Who rewrote General Relativity?
Einstein's General Theory of Relativity seems to have “crashed” as a scientific theory in about ~1960, and to have been "rebooted" some time in the early 1960s as "modern GR" with a different set of definitions and rules that differ from those laid out by Einstein.
I'd like to know who originally made those "redesign" decisions, how the community consensus was reached, and where the changes (and their justifications) are documented.
Background: Einstein had based his theory on the General Principle of Relativity: the idea that all motion was relative, and that even “absolute” motions such as rotations and accelerations could successfully be “relativised” if bodies showing those relative motions could be associated with suitable gravitational/distortional effects. This was an idea previously proposed by Ernst Mach, and Einstein described his general theory as being the theoretical embodiment of Mach's principle.
For derivational convenience, Einstein also initially assumed that the theory should reduce to the physics of special relativity over small regions.
However, the publication of the Harwell group's 1960 paper on centrifuge redshifts (Phys. Rev. Lett. 4, 165 (1960) ) apparently triggered a controversy within the community, and an appreciation that a literal application of the GPoR seemed to lead to results that were geometrically incompatible with special relativity – the consequence of the GPoR being treated as a “law” then seemed to be not only the loss of Einstein's 1905 "Special" theory, but also the loss of the 1916 "General" theory that had been partly built upon it (Schild, Am. J. Phys. 28, 778 (1960) ).
We were facing the unpalatable prospect of a major rewrite of theoretical physics, and although a rederivation of GR to avoid its dependency on SR had already been suggested by Einstein back in 1950 (SciAm 182, 4, 13-17), we found it easier to modify the rules of general relativity to allow the GPoR to be suspended in cases where it seemed to clash with other parts of the 1916 theory. In effect, we accepted that the original “SR+GPoR” structure was logically inconsistent, but maintained order by redefining SR's position in GR's definitional hierarchy to one in which GR could not disagree with SR “by definition”, and establishing a "failure etiquette" ("If the GPoR conflicts with SR, keep SR and suspend the GPoR").
This change seems to have happened with minimal recorded public comment or discussion. Although Schild's paper mentions discussions and "a certain lack of unanimity" in the community as to how to proceed (before he presents the "modern GR" position as unavoidable) Schild doesn't indicate who participated in those discussions.
I'd like to know who was on the committee, who voted for or against the change, and whether any of those concerned published anything on the nature of the 1960 crisis and the chosen response. Does anyone here remember it or have direct personal experience of what happened? Is there any historical record of the episode other than the rather skimpy Schild paper? Did anyone else publish the arguments for modifying Einstein's theory, or the contemporary arguments why GR1916 couldn't continue to be used in its pre-1960 form?
Any references to additional contemporary material would be very, very welcome.
I think habits of thought can be misleading. I would say challenging habits of thought is important in research into fundamental ideas in physics. I would agree that there is a change in configuration when I am moving, but direction and speed only exist because humans quantify them. The universe does not consist of number, or even require number in its fundamental structure.Following
- How can I evaluate the quality of the created 3D model?
Thanks in advance for your replies.
Hi, I recently did a study on the quality of 3D models created with various cameras. My ground truth was a laser scan. In order to compare the models and evaluate the accuracy/deviation I used the open-source program Cloud-Compare.
- Mineralogy of the sediments in Mazotos bay, Gulf of Larnaka, Cyprus?
I am preparing some samples for XRD (X-ray diffraction) of marine sediments in the area of Mazotos bay, Gulf of Larnaka, Cyprus. Can anyone suggest some recent papers about the petrography and mineralogy of the source rocks in this area (sedimentary cover of the Troodos' ophiolite complex, Lefkara formation, quartenary deposits)? I am asking this, in order to be aware and to compare the existing data with my results.
Firstly, i would like to thank you for your recommendation. Nevertheless, the reason i ask this question is that i prefer to have a clear view of previous field research and data in the area which i am going to provide my own work as a first step in order to compare the results after, without being biased of course. I think this will help me not to overrate possible wrong results and , on the other hand, to verify the correct ones.Following
- Is it possible to analyze the soil ecological condition by the analysis of edafobionta?
I would like to contribute some kind of ecological assessment of soil, and ecological analysis of creatures from a soil sounds good, but I am not sure, does it possible to create some conclusion based of analysis of mentioned organisms? If you have some similar articles, please, recommend them to me! I would like to hear your opinion.
Check this about earthworms:
Falco LB, Sandler RV, Momo FR, Di Ciocco CA, Saravia LA, Coviella CE. (2014) Earthworm assemblages in different intensity of agricultural uses and their relation to edaphic variables. PeerJ PrePrints 2:e722v1 http://dx.doi.org/10.7287/peerj.preprints.722v1Following
- What may be the possible reasons of decrease in crystallite size at higher temperatures?
what may be the possible reasons of decrease in crystallite size at higher temperatures? I prepared TiO2 nanoparticles by sol-gel method and calcined at different temperatures but first its crystallite size increasing as temperature increased but further increase reduces crystallite size and then increased again. Any one can help me to explain the reason.
There is also brookite.Following
- What is the alternative test of Chi-square, if there exist many cells have expected frequency less than 5. ?
Chi-square is a statistical test commonly used to compare observed data with data we would expect to obtain according to a specific hypothesis. If we have two categorical variables both of them have 3 levels and the (33.3%) have expected count less than 5, so the result of chi-squared test will not be accurate. What is the alternative test?Following
- Residual DNA quantification of whole organ ECM scaffold?
I am wondering if anybody has experiences running residual DNA quantification on decellularized whole organ scaffolds, for example, hearts?
I am wondering how everybody would sample the organ given the size (porcine heart) and the complexity of the tissue?
Is there any techniques such that it can be done in an efficient/automated fashion?
- Where is it considered soil from the limit with a very weathered rock mass?
I want to know how to recognize soil from a very weathered rock mass.
There is no straight answer to your question. The transition between hard soil and soft rocks is difficult. There are many references on the subject with different approaches to the subject so you should check for the different methods. As previously stated you can use the compressive strength. Also you can use GSI system (by Hoek-Brown). If GSI falls around 20 the methods for rock mechanics does not apply so you should use a soil approach. Nevertheless as I stated there is no definitive answer to your question.Following
- Where can I find Balb/c mouse genome sequence?
Hello. Anyone knows how to find the genome sequence information for Balb/c mouse? It seems the default sequence on general database is from C57BL/6J. Thanks.
You can find it here: http://www.ebi.ac.uk/ena/data/view/ERS076386&display=html or look through this list here and see if any catch you eye: http://www.sanger.ac.uk/resources/mouse/genomes/Following
- Does anyone have any experience using a go pro in ecological studies?
Students and I were thinking we might pair a game camera on one end and a go pro on (say a dog) and observe the response of domesticated and wildlife caught on both cameras. Any thoughts/suggestions? Any articles out there, as we haven't found many yet?
In addition to Alex's answer:
The wide angle defaut setting can be changed. The angle of the Gopro camera can be set as wide, medium or narrow, with the same resolution. This gives a certain flexibility of use.
The minimal focused distance is about 45 cm. Nevertheless, the use of additional close-up lens reduces this distance and allow very close images.
We are using a set of modified Gopro with an external alimentation (a car battery) and deported screens for fish monitorings.Following
- How can I get rid of smear on PCR products?
I am having trouble getting rid of the smear that runs the whole length of my gel.( above and below the desired band) I am wanting to amplify a 938bp PCR product as well as a 250bp product. Previously I was not getting the smears, but now all of a sudden they have come up in the last 3 gels- and were even coming up in the negative control (even after using fresh stock of everything). they also come up regardless of what DNA sample I am amplfying.
On the latest gel, the negative control (although it was contaminated at some point) was the only lane to not show the smear. I dont know why it would be the concentration of the DNA now, given that I've been using the same volumes before and only now I'm having the problem with the smearing.
35x cycles of 94c/30sec, 63c/30s, 72c/30s
ANY ADVISE WOULD BE MUCH APPRECIATED!Following
- How do you measure hierarchy within a complex system?
For a given complex system, what measures, scales and/or method could you suggest to unveil a relational hierarchy among components?
I understand your concerns, so let me explain myself.
Let us change the designation of ‘axioms as rules’ and go back to their usual definition as ‘self-evident statements’; i.e., statements that we all agree are true [o en español de mi pueblo, afirmaciones de Perogrullo].
Then, by stating a formal set of consistent self-evident statements which any complexity measure should comply with, I am just stating that any proposed complexity measure should comply with a consistent set of statements that we all agree are true.
In relation to the representational problem, let me use a political example. Arrow  when reviewing the possibility of defining social welfare functions, he states two conditions to consider that a decision is ‘democratic’ [he establishes a total of five conditions for his Impossibility Theorem, but the first three only refer to rationality, not to democracy]. Now, a social welfare function is a decision that represents a society, hence let us consider that a scientific theory is sort of a societal decision [since it should be useful for a society, and it is composed buy statements each of which can be considered an individual decision]
The first condition is that the decision must not be taken by one person, which of course the theory fulfills. Though I wrote the book myself, a lot of relevant authors' ideas are often presented and commented in the book, and used as basis for my proposals. I attach the list of references for the book so you can have an idea [in my view one can expect the contents of a book largely depending on the references from which it buids]
So, if we go back to the example of the city, I think the best we can expect from a politician is that he makes hi decisions building on the best available knowledge, which is what I have done.
The second condition is that the decision cannot be imposed, and that is out of the question; I cannot force anyone neither to believe nor to follow my ideas. That is up to anyone.
Another issue you pose is to let stakeholders participate. That has been my intention through all the process, which I have done by three ways:
• By publishing excerpts of the book and several articles, some of them have been seen by many people, and some posts which have received many comments [mainly in linkedin].
• By making short presentations to increase the possible viewers [‘Of the complex, the simplex and the noncomplex’ has more than 1500 views by now in Slideshare]
• By taking into consideration any comment received.
As for now, I can tell you that at least two comments have forced me to introduce some amendments. One made by Dave Snowden in relation to the meaning of ‘simple’ in English. The other made by Bojan Radej in relation to some features of chaotic systems. [Thta is after the book was first published. Before publishing, the book was read and commented by four persons, though only one of them had worked in the field of complexity]
But also, if we follow the example of the city policy, we could say that I am trying to achieve the highest transparency possible with my proposals. I clearly explain the basis [self-evident statements] I clearly state the deductive rules [rules of logical inference] and I clearly state the conclusions. So differently from other theories and proposals, the theory can be totally or partially disproved if anyone proofs that any of the axioms is not so self-evident, or that the rules for logical inference are not correct [this is actually a characteristic of any formal theory].
In relation to your second claim; the obsolescence problem, I believe the need of constantly adapt/evolve is inherent to any knowledge, hence to my proposals also. Anything we discuss now will probably sound weird or naive in some years… But if we do not discuss it now, we will not progress in our knowledge. However, history shows that formal theories usually survive longer ….
And in relation to your third comment, the axioms are quite general. Somehow, they resemble ‘logical rules’ which are inherent to any reasoning. But we do not feel like they constraint our possibilities for reasoning, we just think that they prevent 'non-logical thinking'. The proposed number of axioms, definitions and rules, let room for an almost infinite number of proposals…
And last, and at this point I disagree with you, figuring an algorithm that is able to describe and predict the behavior of the actors of the city is not only totally far away from my interests, but in fact is something that really worries me.
From some time ago, we are able to make approximate predictions in relation to socio ecological systems [SSE], through several types of statistical techniques. But lately, a group of scientists are trying to develop new methods for making even more accurate predictions [Agents Base Modelling, etc…]
For me, if we accept free will exists, it will never be possible to fully accurately model and predict the behavior of ‘human actors’. But also, any progress from the kind of ‘approximate predictions’ we can already build on statistics will be at the cost of diminishing people’s freedom [please see PS1 for some exceptions].
Not so long ago [I believe it was 2011], Leonardo Rodriguez made an interesting comment in one of his articles. He suggested that the reason most Latin-American scientists are more interested in the epistemic side of complexity [complex thinking] while most north American [and in general, northern countries] scientists are interested on the modeling of complex behavior [e.g., human societies] lies [largely, not completely] in the interest for ‘control’; military control, economic control … underlying such research.
Many studies of this type are financed by the army or private companies, and let us not be naïve; side by side to the will of predicting these behaviors walks the will of anticipating them hence control them [see ps2].
To be honest, that is the really scary face of complexity science today, not my proposed formal theory that is just a set of logical rules and some formulations, which any scientist has the possibility to believe, not believe or simply question.
PS1. I do not state that agent based modeling is always bad. In fact, it has some interesting applications such as modeling planes dynamics in airports, and others. I just claim that trying to achieve the possibility of making totally accurate predictions on human behavior could only be possible at the loss of individual freedom, something not to be accepted.
Ps2. The importance of being able to predict other people behavior can be rooted back as long as Sun Tzu who claims that an army has to have no defined shape so their enemies cannot anticipate their movements. Basically what Sun Tzu is claiming is that if at some moment we believe that our enemies are able to anticipate our behavior [we have become predictable], then we should modify our behavior.
In more recent terms, a similar behavior is undertaken by any good poker player.Following
- Has credentialism had an impact on what it means to be educated?
In higher education with current curriculum requirements necessary to receive a credential/degree I fear restricts students exposure to other avenues of thought that are of importance. As electives become fewer and class size requirements to "make" become higher what are some potential future risks to students intellectual curiosity? In limiting the topics of study which can be included into the degree what are some possible unintended consequences? Does the phenomena of centralized social actors change your views on what it means to be educated.
Please explain your answer.
Given many problems associated with current credentialism-oriented higher education and societies, I believe there is always space for educators/teachers/professors in every classroom to expose students to various meanings of 'educated' and learning via their own approaches to, understanding of, and concerns about education and learning.
Out of very commercialized or very discipline-focused or superficial social justice-obssessed educational settings as I have been experiencing and observing in various countries, there are always students who are genuinely striving to be 'educated' in the ways you have described above, and are demanding the kind of education that would inspire them to achieve their aspiration.
So if those working in HE do not give up hope and do not stop leading by example and continue to improve themselves and engage in 'educated person' aspects of teaching and learning, then I see credentialism as being just a phase, and as being one of many competing doctrines and practices that exist side by side with all other tenets and values.
Many thanks for the question and for your insights into the issue too.
- Are you an on pump or off pump cardiac surgeon ?
On pump versus off pump CABG what are your reasons?
Important question: answer should be that we should use the right tool for the right job. Issues include, but not limited to, the technical quality of distal anastomoses (and related patency), number of grafts (commonly less with OPCAB), reduction of symptoms, and long-term survival.Following
- How to appropriately account for errors when fitting a mathematical model to summary data which represent percentiles (e.g. median) of a histogram?
The data provided are percentiles (median, 75th and 90th) from several histograms. The number of observations comprising each histogram is known. The shape of the data distribution in each histogram is not known, but may be closer to Gamma or log-normal than to normal. When I fit a mathematical model to the summary data (percentiles), how do I calculate the error bars to weight each point appropriately? I would appreciate suggestions from anyone interested!
Shane provided a very good approach via simulation. I've done this several times when I had summary data provided in papers, but not the detail. Your data will obviously not look exactly like that you're trying to replicate, but it should be pretty close. The problem will likely be with the bin sizes, unless you happen to know the bandwidth originally chosen.Following
- How is it possible to develope uncured photoresist placed inside micro-scale fluidic channels?
One possible microfabrication approach that bypasses the step of bonding involves only deposition of resists by spinnng, UV photolithography, and cure. Nevertheless, the last step to accomplish such a method requires the development of solid uncured resist which is placed between two (top and bottom) other slides generating microstructures.
Follows the picture. The development in wet medium did not remove the uncured SU-8 even with the aid of ultrasound bath.Following
- Why is it necessary to convert ADS data to FDS data in an XRD pattern?
Why is it necessary to convert automatic divergence slit data to fixed divergence slit data for phase quantification in XRD?
F is the structure factor.
- When performing alkene metathesis, how can I ensure cross metathesis as opposed to homodimerization?
I am a fledgling chemist, and today I performed some Grubb's catalyzed (1st generation) alkene metathesis. I wanted a cross product between camphene (4.87 mmol) and 2-methyl-3-buten-1-ol (4.78 mmol). Upon mixing these together in a 1.5 mL centrifuge tube (camphene is soluble in the 2-methyl-3-buten-1-ol) and adding 5 mol% (0.20 mmol) of the catalyst, there was nothing discernible about the reaction, and this seemed to be far too much catalyst.
So I repeated the experiment with much less catalyst (a tiny un-weighed spatula full) and my colorless solution of alkenes turned a brown/tan color. I thought that I had made the cross metathesis product, but I also performed a control experiment in which I only used 2-methyl-3-buten-1-ol and a small amount of the catalyst and the solution still turned the brown/tan color.
I believe as a result of this that I am forming the homodimer (2,5-dimethyl-3-hexene-2,5-diol), and not the cross metathesis product. I tried different ratios of camphene and 2-methyl-3-buten-1-ol, but got the same result. Any and all advice/tips/tricks on how to perform this reaction would be greatly appreciated.Following
- What kind of analysis would be required to compare individual cases to the group mean over time?
If I had a data set consisting of ratio level data for 10 years for, say, 100 companies, what kind(s) of analysis might I need to do to determine which companies data varied most from the mean of all companies. Essentially what I’m trying to ascertain, is do some companies in the data set move more, over time, than other companies, when compared to the group average?
Does anyone know what kind of analysis I might be looking at doing? (Probably I’ll try and find someone with expertise in that area).Following
- What kind of internal standard could be used when measuring concentrations of phospholipid fatty acid in human plasma?
Usually, we use thin layer-chromatography to separate phospholipid from total lipid in our lab. I would like to know what kind of internal standard could be used when quantitatively measuring the concentrations, not the relevant content, of phospholipid fatty acid in human plasma?
I agree that di-17:0 PC should work. But may not be simple, since there are probably
- What is this fluorescence material in my DNA sample ?
I extracted DNA from several hundreds blood sample by promega kit , one sample among all the others show a two clear fluorescent bands migrate to the negative pole , those bands appear without any staining just uv 310nm irradiation as in the gel image below . the bands color are red to orange ,
Can anyone tell me what is this , why , any idea ,?
'DNA from several hundreds blood samples'
Think about this.Following
- Could somebody help to find this publication?
My colleague from department is looking for this paper:
BEUKEMA, J.J., G.C. CADIE & H. HUMMEL, 1983. Differential variability in time and space of numbers insuspension and deposit feeding benthic species in a tidal flat area.- Oceanol. Acta, Nr. Spec., Proc. 17th Europ. Mar. Biol. Symp.: 21-26
Unfortunately it couldn't be found in all main scientific libraries of Saint-Petersburg and opened internet sources.
Maybe not specifically what you want but nearest I've found (containing
historical information covering your period)
- Should I use a specific formula to compute my sample size to match a Liket scale questionnaire?
If so please kindly specify the of formula for sample that is usually recommended for a Likert scale questionnaire
If you use Stata, I wrote a program that will provide you with the sample size for your problem. This issue is common in implementing surveys. Within Stata, type: ssc install svysampiFollowing