Q&A

ResearchGate Q&A lets scientists and researchers exchange questions and answers relating to their research expertise, including areas such as techniques and methodologies.

Browse by research topic to find out what others in your field are discussing.

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Do photons interact with gravitons?

The graviton is a hypothetical elementary particle that mediates the force of gravitation in the framework of quantum field theory. If it exists, the graviton is expected to be massless and must be a spin-2 boson. The spin follows from the fact that the source of gravitation is the stress–energy tensor, a second-rank tensor. But by no means is it universally accepted.

But there are many articles about the interaction between Photon and graviton or graviton-photon scattering.

http://journals.aps.org/pr/abstract/10.1103/PhysRev.128.2414

http://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.064008

How can graviton's mystery be solved?  Should graviton be detectable or like photon (same as photoelectric effect) be able to explain the physical phenomena?

Stam Nicolis · University of Tours

If the transformations don't preserve the speed of light, they break Lorentz invariance-and it's easy to prove that the Lorentz transformations are the *only* transformations that have this property, up to the usual equivalence relations. Spacetime transformations are, first of all, classical and, second, don't have anything to do with phase space transformations. So they don't have anything to do with wave-particle duality. All the remaining statements can't be given any meaning, or are contradictory, since energy transforms as the zero-th component of a 4-vector under Lorentz transformations.

Is RIPA buffer fine for isolate protein from cancer cell lines for gel-free proteomic work?

can i use RIPA buffer (Sigma) for isolate protein from cancer cell line for proteomic work. we have waters nanoAcquity QTof LC-MS/MS systems for analyse total proteom of cancer.

pls suggest nice protocol for my experiment

Ilian Atanassov · Max Planck Institute for Biology of Ageing

The RIPA buffer is not suitable for the extraction of the whole protein content of the cell. It is more suitable for the extraction of soluble cytosolic/nuclear proteins. Better go for something with more denaturing power such as 8M Urea or 6M GuCl or 2 o 4% SDS.

Here is a manuscript in which the researchers compare RIPA and Urea for protein extraction and LC-MS/MS analysis:

http://www.proteomesci.com/content/pdf/1477-5956-6-30.pdf

• Arun Prakash asked a question in FFT:
Why Decimation in Frequency (DIF) FFT algorithms? what method of FFT algorithm is implemented in MATLAB?

Considering number of computations involved in computing FFT using DIT and DIF, there is no difference. Are there are any other important difference?.

My second question is: Although there exists many FFT algorithm in literature, what method of FFT is implemented in MATLAB? I implemented 8-point FFT using DIT and executed it. But, taking FFT using MATLAB inbuilt fft() takes much less execution time than my FFT function.

• Azam Shamsian asked a question in DMSO:
Dissolving human serum albumin in DMSO

I have a sample of human serum albumin that should be dissolve in an organic solvent miscible with water like DMSO. but it does not. even 1mg/ml. How can i disslove it?

• Prosenjit Pal asked a question in Parkinson's Disease:
Anybody help me to get PINK-1 and DJ-1 Knockout cell line?

I am working on Parkinson's disease pathogenesis and try to establish the role of PINK-1 and DJ-1 in cellular model of PD. I want to check the downstream effect of some mutations of PINK-1 and DJ-1 and for that reason I need knockout cell line for PINK-1 and DJ-1. If anybody working in this area please help me out.

What are the pros and cons of the EFQM Business Excellence Model versus the ISO model for SMEs ?

Both the European Foundation for Quality Management and the International Standards Organisation have quality standard frameworks for enhancing the business practices of outward-looking export-oriented SMEs. Are they competing frameworks? Am interested in uncovering the pros and cons of these two frameworks?

Silburn Clarke · The University of the West Indies at Mona

Thanks Manuela,

Many large firms do act as locomotives in the value chain as well as in globally integrated supply chains. Where these large firms are more advanced in innovation, quality processes, high standards in operating practices, productivity and competitiveness then they can enforce SME's in their B2B chain to adopt their systems of quality standards.   On the other hand, it has also been observed/reported that in some chains, the script is reversed.  In some chains the SME partner may be more advanced than the large firm,  in their quality standards and processes,  and so in those cases are inhibited in their potential until,  if and when,  the larger firm catches up.  A case of the coaches encouraging the locomotives to be better.

Silburn

• Napoleon Ono Imaah asked a question in Function Spaces:
Which or what areas, functional spaces or things are you tempted to see when you visit other people's homes?

What do you want your visitors not to see whenever they visit your home?

• Houssam Nahilia added an answer in Wind Power and Power Systems:
Does anyone know about models of DFIG in power system transient stability?

I want to study the impact of DFIG based wind generator. what's is the best model to choose?! please help.

Houssam Nahilia · University of Science and Technology Houari Boumediene

i want to see the transient stability of wind farms integrated in power systems.

Is Chalmers' so-called "hard problem" in consciousness real?

In his 2014 book "Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts" Stanislas Dehaene wrote "Chalmers, a philosopher of the University of Arizona, is famous for introducing a distinction between the easy and the hard problems. The easy problem of consciousness, he argues, consists in explaining the many functions of the brain: how do we recognize a face, a word, or a landscape? How do we extract information form the senses and use it to guide our behavior? How do we generate sentences to describe what we feel?

“Although all these questions are associated with consciousness,” Chalmers argues, “they all concern the objective mechanisms of the cognitive system, and consequently, we have every reason to expect that continued work in cognitive psychology and neuroscience will answer them. By contrast the hard problem is the “question of how physical processes in the brain give rise to subjective experience … the way things feel for the subject. When we see for example, we experience visual sensations, such as that of vivid blue. Or think of the ineffable sound of a distant oboe, the agony of an intense pain, the sparkle of happiness or the meditative quality of a moment lost in thought … It is these phenomena that poses the real mystery of the mind”."

Stanislas Dehaene's opinion is "that Chalmers swapped the labels: it is the “easy” problem that is hard, while the “hard” problem just seems hard because it engages ill-defined intuitions. Once our intuition is educated by cognitive neuroscience and computer simulations, Chalmers’ “hard problem” will evaporate".

Personally, I agree with Stanislas Dehaene's opinion.

Bernd Schmeikal · University of Vienna

We really do have profound problems in understanding experience and relations between experiences. We should be able to declare a way how we understand something and how we gain insight, a way that could turn out obliging, not only for the troup of acrobats in cognitive science, but also for people who just experience their living with no capacity to enter the hall of fame, say, of constructivism or any form of cognitive wrestling.

Reading a paper today, I already (after breakfast) came upon three fundamentally different concepts of transcendence, the first approached the extraordinary locus of god/observer, the second was based on meta-meta-meta science, the third was the mere, but noble, transcending 'ego' by finding eye-contact to the other. Now, Louis may go beyond 'ego' and claim that he believes something, and leaves it open to the other to answer and perhaps modify his belief. I think this is a rather human standpoint, after all.

Is it necessary to have bilingual experts (with formal education) for translating a questionnaire?

While testing a questionnaire for its validation and cross-cultural adaptation, is it necessary to have bilingual experts with formal education? E.g translation of Nordic questionnaire into Urdu (is it necessary that the translators have a formal level of education/degree in Urdu or English?)

Could it be done by someone who is brilliant at both languages but does not have formal education?

Secondly, how is the sample size selected for translation-based studies like this? Inclusion and exclusion criteria and number of participants etc...

Thanks in anticipation.

Nai-Kei Wong · The University of Hong Kong

In the commercial questionnaire validation practice, the process is actually very costly and elaborate. It may proceed by:

(1) first defining the questionnaire items (questions, scales) in a language that is most clear in articulating the concepts (e.g. English or French);

(2) cross-validating this source text by editors and proofreaders, and pre-testing it by subjects, followed by more editing and revision so that accuracy and precision can be guaranteed.

(3) after that, commissioning a professional translator (usually freelancers such as those at Proz.com in an ad with pay, or by recruiting reliable volunteers) to translate the source text into a target language. This translator is usually a native speaker of the target language;

(4) after that, commissioning another pro translator and native speaker to translate the same text.

(5) a third native speaker, usually a very experienced language expert, is tasked to "pool" (integrate) the two translated texts into a unified version.

(6) this unified translation is sent to an outsourced editor (anther native speaker, bilingual) to check (edit and proofread, etc.) the accuracy and precision of the translation, comparing items on the source text

(7) after that, the translation is to be  validated and pre-tested in local subjects who speak the target language. Local interviewers (usually one, on pay) will be appointed to recruit such local subjects. The questionnaires will be tried out by the subjects. The subjects will be asked if there are any items that are not clear to them (these constitute the basis for improving the clarity and accuracy of the translated questionnaire). The results of subject feedback will be summarized by the appointed interviewer, and sent back to the commissioning agent.

(8) an editor (bilingual expert) recommend changes based on local subjects feedback to the translated text.

(9) after final proofreading, it's finally done.

***

Such expensive and labor- and capital-intensive questionnaire validation work is practiced by commercial medical survey companies in the UK. They recruit trusted freelancers at Proz.com to provide the service.

Occasionally, volunteer's help is available, and the people at Proz.com are friendly.

***

In commercial survey validation, the local subject sample size is typically 5, with different age and sexes.

For academic research purpose, the sample size would be determined by normal statistics considerations.

You may need to control for sex and age cohorts.

Minimal sample size is 30 for normal distribution (have 40-50 to be safe). And of course, the larger the sample size the better. (However, if your questionnaire is large (over 20 items), practically, it would not be possible to have many subjects happy to give you the answers. Processing and analysis costs will also be blown up.

What is in the power system load modeling?

Is it ok to take the excess of formalin (10%) from the fixated tissue with running water before storing it in 70% ethanol?

I am in the field at the moment and therefore I can't get PBS to clean the samples after fixation to remove the excess of formalin. I wonder if there is any problem if running water is used, or if it is actually mandatory to remove the excess of formalin. Thanks in advance for the help.

Muhammad shuaib Khan · Putra University, Malaysia

Better to rinse in running Tap water for 03 to 05 minutes

What are the appropriate stains for Cyanophages when studying their adsorption using flow cytometry?

Currently we're using SYBR Green and Gold to stain cyanophages but the natural florescence of Synechococcus sp. WH7803 makes it much harder to quantify the adsorption rates of the cyanophages. Are there other DNA stains that can be used to study viral infection but emit different wavelengths other than green (or any range not detected by FIT-C or FSC-H)?

Claude Belzile · Université du Québec à Rimouski UQAR

Re-thinking about your question Vinh Tran, if you cannot measure an increase in the background green fluorescence of Synechococcus after SYBR-labelled cyanophages adsorption, it is unlikely that an orange DNA stain will provide better results.

A red stain would probably not work either, because of chlorophyll fluorescence around 680 nm.

• Soumendra Nath Panja asked a question in Critical Exponent:
Is mott transtion is a universal transition with particualr order parameter as Magnetisation ,Polarisation with specific value of critical exponent?

Any experimental verification so far.

Is there any better technique to prevent tissue detachment from the slide for frozen IHC?

Hi, I'm processing osteochondral tissue for IHC using pre-fixed (Z-fix- 10% formol + 1% zinc) decalcified (Decal solution - formic acid) on OCT embedded samples. However, I'm having some issues regarding transfer the tissue to the slide (I'm using CryoJane Tape-Transfer System) and detachment of the tissue from the slide during the immunostanning process. Anyone have a good tip to help me?

Muhammad shuaib Khan · Putra University, Malaysia

I also faced same problem once and than changesd the brand  and used the silanized one, also i faced same problem when we were using self prepared Poly-lysine coated slides.Better select Good Brands or try silanized Slides

How do I measure the density of small quantities of material (glass)?

I need to measure the density of glasses, which unfortunately I got in very limited and small quantities: around 50 mg, both in powder form and in bulk. I have been trying so far: Archimedes's method for determining the density (in ethanol - water sensitive material - and in air), Guy-Lussac pycnometer (the smallest I could find - 5ml - encountered problems with this also because of the liquid medium: ethanol/isopropanol, due to rapid volatillization). I have access to helium pycnometer as well, but to my knowledge, I need at least 2 g of sample for accurate determination. If somebody encountered this problem likewise, I would like to hear about a solution. Thank you in advance.

Dmitriy Ivanenko · Expert-Service, r&d corp.

You can try to pour the powder fusible plasticine with a known density (~ 5 grams) and the known volume. Then measure the volume of the resulting mixture. To avoid cavities, a liquid mixture was ultrasonically treated. It is possible and without ultrasound, If we select enough melting plasticine. For some substances it works.

Evaluating the Integral in "No-sum" closed form

Dear All,

I would like to know if the following integral $\int\limits_{0}^{\infty} \dfrac{\arctan \left(x t\right)}{\sinh t} dt$ where "x" is an arbitrary real constant is evaluated in CLOSED FORM. The value of the integral should be a function of "x".

Clearly the numerical evaluation of the integral is feasible via the Gauss-Laguerre quadrature rules, but I stress on having a closed form expression.

Also, the possibility to expand 1/sinh(t) as an infinite series in exponential powers where the Laplace transform of "arctan(xt)" is then evaluated, is definitely considered before (see my previous question) and we are looking for a "more compact" expression.

Finally, the integrand is analytic at "t=0" and is even in "t", thus the integral form $-\infty$ to $+\infty$ is simple double the integral from 0 to $+\infty$

If by chance you have  encountered this integral in a reference or so, let me know...

What is the influence of surface properties (roughness, surface tension) on the heat transfer coefficient by convection h?

I try to find a coating for cutting tools that can withstand the low temperatures and thus why our coating must have a high capacity evacuate heat , so h is maxiamal

Pinaki Ranjan Sanyal · Kuwait Oil Company

The velocity will be affected by the surface roughness which in turn will affect the heat transfer by convection.

Fermi energy in Graphene nano ribbons?

I am simulating graphene nano ribbons,and i want to add my magnetic field term in Hamiltonian,is there any other method than Pierls Substitution or not.

regards

Surender Pratap · Birla Institute of Technology and Science Pilani

Thanks Simchi sir,but i want to add electron-electron interaction like earlier i have done by adding Schrodinger -Poisson solver self consistently solving,as well as electron-phonon interaction.If only one field is applied  ,either of Electric and magnetic field time reversal symmetry of the energy bands  for electrons and holes is preserved ,but WHY this sir However combined effects on the energy dispersion is to break the time reversal symmetry for both electrons and holes and mix the energy bands.

regards

Tunnelling Effect Correction?

Hello,

I have been trying to include tunnelling correction to my rate constant and activation energies, but it is not clear how apply it and how to calculate it. In some studies they used Truhlar correction but I don't have access to the study and the complete formula to use it.

Also, should I perform extra calculations or with gaussian results of my TS it is enough?

Thank you very much

Joaquim Mª Rius Bartra · Autonomous University of Barcelona

Hello Fatemeh,

I tried the equation but the second part of equation its too much small, in order of 1E-22 in front of 1. My reaction is a bimolecular reaction without intermediates. It is valid in this case or simply Qtuneelling is 1 in this case and have meaning?

Joaquim Mª Rius Bartra

I am collecting qualitative data, and it's unstructured with open ended questions, how can I best analyse this data?

How can I disable autoconf feature of IPv6?

I have tried to do it by disabling accept_ra and autoconf feature. But, it is not working. Is there any way. Actually, I want to assign static link-local IPv6 address. But when I assign it and go for "ifconfig", it displays "TWO" IPv6 addresses. How can I stop that auto-generation of link-local IPv6?

Neel Tailor · Nirma University

If due to some problem link-local address does not generate , my device can not communicate. So, for that I am assigning one static IP. I have done these all things suggested by valter and juan but still there is auto generated ipv6 address.

How can we use Matlab for the elliptical fourier analysis of biological organisms?

for shape size and morphological determinants

Vinay M. Raole · The Maharaja Sayajirao University of Baroda

really I have to understand the formula from the mathematician.

Which ANOVA Test is Better for my data?

Hello to everyone.

First I want to say that I checked other similar questions uploaded here but I am asking because I still don't know for sure whether I am doing the right statistical test for my data.

Here is an imaginary example (check the attached picture). Lets say I have a T cell suspension, samples of which I treat with different concentrations (A, B, C, D) of a given drug. I have a total of 3 subsets of samples (one set of cells that are non activated, a set of anti-CD3 activated cells, and a third one activated with PMA+Ionomycin). The role of controls is served by untreated with the drug cells (denoted as "Cells only" on the figure).

Let me note that I am using GraphPad Prism to make graphs and do analysis. Therefore, if I want to perform a statistical analysis of the data above I should use Two-way ANOVA test with Boniferroni's post test, right? I come to this conclusion since both the activation of cells (anti-CD3 or PMA/Ion) and the drug used for treating the samples may affect the output. Am I correct?

Moreover, if I build new graphs for each of the subsets (Non-activated, anti-CD3 activated, and PMA/Ion activated) and use One-way ANOVA with Boniferroni's or Dunnet's post tests instead and compare the results for "Cells only" with the results for concentrations A-D, then this analyzing will not be correct due to the fact in this way I will omit the effect of the activation of cells and just consider the effect of the drug. Am I correct on this one?

Jochen Wilhelm · Justus-Liebig-Universität Gießen

Again you do not mention what your "output" actually is. It it a oncentration measure? Are these counts of cells? Are these proportions? This is important to consider because you have a very small N. It will help to find reasonable assumptions for the probability model that should be used to fit your model.

From the plot you showed I would guess that either a negative binomial model or a log-normal model would be possibly adequate. The log-normal model is very simple to fit: just use the logarithms of your "output" (response) and run the 2way ANOVA. Then check the residuals with a normal-QQ plot and a residuals-versus-fitted plot to see if the data shows relevant violations of the assumptions (normal distribution, homoskedasticity). If this looks fine, then you may use this model to test your hypotheses. The simplest approach is to run all the pair-wise t-tests using the pooled variance estimate from the global model to estimate the standard errors. The series of p-values should be corrected for multiple testing.

"As for the normality, I believe this does not play a major role in biological experiments since most data obtain from complicated live systems do not show normal distribution and in my case I also don't have a big N?"

Yes, data from biological systems is usually non-normal. Very often it is log-normal (that is: the effects are proportional to the response value - something that makes pretty much sense for such systems!). The distrubutions are often more complicated leading to the more general gamma distribution (that actually allows for a variation of the scale parameter of the log-normal distribution).But practically most data can be fit reasonably well by a "simple" log-normal model (since there is also often not enough data to estimate the scale parameter with sufficient precision anyway).

Non-normality should not lead to change to "non-parametric tests", because you loose any quantitative informaion about effect(sizes) that address the biological relevance of your findings. It should rather lead to think more about a good model (including both: the deterministic and the sochastic part). This will (usually) lead to a better understanding and new and relevant insights.

What parameters can I study on CSF samples?

I am collecting CSF samples from neurodegenerative patients.

I am currently doing galectin-3 and MMP-9 assay. Please suggest other assays as I want to utilize every drop of the precious |CSF samples.

Anthony G Gordon · Independent Researcher

It is much better to test a specific hypothesis about a specific disease, since if it is just a fishing trip, any positive finding is likely to be impossible to explain or assimilate.

How can I minimize the inrush current in a power converter?

We know that the inrush current is refer to the maximum instantaneous input current drawn by an electrical device when first turned on. But, how the inrush current in power converter can be minimized effectively?

Morteza Kazemi · Tarbiat Modares University

hi
all converter has a control circuit to generate switching pulses. you can use this control circuit for soft starting purpose but in some converter like boost converter you have to use additional component like NTCs or relay and resistor as  Francesc Casanellas mentioned before.

Datasets for Big Data?

Which is best source for Big Data datasets for a network traffic generator i.e. all kind of network trafic.

What are the reasons for smeared bands on agarose gel?

Hi,

For the past week all my pcr products are giving me smeared/non-specific bands on the gel. This had not happened so far.

I thought this was due to new stock of primers, but when I re-tested it with other primers, I am still getting smeared bands.

I am attaching 2 images to show the difference in bands that i am getting.

What could be the reason for this?

Padmagiri G.C. · Indian Institute of Science

@Christian and @Laurence, Template is crude genomic DNA and we used the same template on both the gels. But it is not possible that the DNA is degraded because they were freshly prepared only a month ago. Could polymerase really be the problem? because it was working just fine until last week.

I am interested in finding out how firm conclude what should be co-created with customer and what should be done in house?

We are interested in upto what extent its acceptable for the firm to allow its customer to be engage and why

Marcel Weber · Windesheim University

Hi Faisal. In essence, anything can be co-created with customers, as long as the firm has a customer focus and you can use techniques to access customer knowledge (von Hippel calls it "sticky information"). However, to decide whether or not to co-create with customers I have developed a decision framework, see my dissertation (https://www.researchgate.net/publication/236678729_Customer_Co-Creation_in_Innovations._A_protocol_for_innovating_with_end-users?ev=prf_pub) based on three questions:

- how open do you want your project to be? If you want to be secretive (because of competition) about it, co-creation might not be advisable

- in which stage of the innovation process are you? The further and later you are, the greater the costs of co-creation may be

- how complete should the customer input or idea be: raw ideas or market-ready? In the latter case you might give preference to seek answers from professionals or lead users.