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.

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  • Bhupendra Pratap Singh asked a question in Isolation:
    What is suitable Range of voltages for Octocoupler or Photocoupler?

    an opto-isolator, also called an optocoupler, photocoupler, or optical isolator, is a component that transfers electrical signals between two isolated circuits by using light. Opto-isolators prevent high voltages from affecting the system receiving the signal.

  • Is anyone familiar with uncertainty analysis in CFD?

    At present, i am working on this topic for ship flow problems. Experimental uncertainty is totally different. Does the uncertainty analysis mean the same thing with mesh dependency in CFD? 

    Shrish Shukla · Indian Institute of Technology Delhi

    Hi omer,

    I am also working in the area of ship & helicopter flow problems & here i am enclosed a literature thesis which help you to understand the uncertainty phenomena as well as the difference with mesh dependency.

    Good Luck !

    S. Shukla

  • Dan Matheson added an answer in Software Process:
    How do we convince software practitioners to use a new software development process?

    What criteria or factors should the new software process has to convince software practitioners to use it?

    Dan Matheson · Colorado State University

    Jerry - sorry for the delay I was in the mountains and not connected.  There was no tool in the sense of a computer-based tool.  The tools were mostly mental, getting people to think differently and approach the problem and the process differently.  Not just thinking outside the box, but throwing the box away in some instances.

    The driving factors were my experience and frustration with text-based requirements, the inability to be agile (incremental and iterative) with text-based requirements, and a desire to use an engineering approach to software solution development as in other engineering disciplines.

    For the graphical specification of the requirements we used a UML tool internally and VISIO for the customer facing graphical artifacts.  Now that I have this experience I can envision computer-based tools and improvements to the UML to support the modeling of requirements.  I shall continue researching these ideas.

  • Shinsmon Jose asked a question in Lenti:
    How does the Cignal Lenti Viral reporter system integrates into the host genome?

    I am doing GFP transfection using Cignal Lenti viral reporter system for the purpose of tracking my cells  (bmMSC and Fibroblast). The reporter system is said to provide a stable transfection upon transduction followed by clonal selection. However, I am not clear about the insertion of the expression system into host genome? How does it work? is it a random insertion? I am bit concerned about losing the natural function of these cells (becoz of a random insertion into any of the vital genes) upon transduction.

    Leave your comments here, any sorts of related discussion will be appreciated.

    Cheers!

  • How do you experimentally get d-band center energy values?

    Hello, I'm interested in getting d-band center values for some samples. I've read some papers where they get them from XES, XAS and UPS but they don't explain the data analysis process they use in order to get them. Can someone please recommend some papers with some explanation of data analysis for these or other techniques?

    Besides my main question, is it possible to get these measurements in powder samples? If so, can someone recommend some papers where they do this?

    Thank you!

    Maddali V S Murali Krishna · Chaitanya Bharathi Institute of Technology

    The surface composition of Cu(In,Ga)(S,Se)2 (“CIGSSe”) thin films intrinsically
    deviates from the corresponding bulk composition, which also modifies the electronic
    structure and thus the optical properties. They have used a combination of photon and
    electron spectroscopies with different information depths to gain depth-resolved
    information on the band gap energy (Eg) in CIG(S)Se thin films. They have found out that an increasing Eg with decreasing information depth, indicating the formation of a surface region with significantly higher Eg. This Eg-widened surface region extends further into the bulk of the sulfur-free CIGSe thin film compared to the CIGSSe thin film.[1-2]. 

    M. Bär, S. Nishiwaki, L. Weinhardt, S. Pookpanratana, O. Fuchs, M. Blum, W. Yang, J.D. Denlinger, W.N. Shafarman, and C. Heske, Depth-resolved band gap in Cu(In,Ga)(S,Se)2 thin films, Appl. Phys. Lett. 93, 244103 (2008).

    2) D. Briggs and M.P. Seah, Practical Surface Analysis by Auger and X-ray Spectroscopy, John Wiley & Sons Ltd., New York (1983).

  • Mohammed Yaro added an answer in Molecular Biology:
    Do you prefer blind review process of your research paper?

    Some journals get their research reviewed after hiding the names of the authors. What is your preference and why? What is the fair review process: blind or open

    Mohammed Yaro · Biotechnology and Nuclear Agriculture Research Institute

    I definitely do prefer blind review process even though it might not guarantee a fair process on every every single manuscript, it will surely also not hurt the process too.

  • Can we measure motivation in students?Are there any standardized questionnaire to measure?

    This question is regarding medical education.

    a) How will we know that a student is motivated to learn the subject ?

    b) Is it intrinsic motivation or extrinsic motivation?

    Saileela Kondapaneni · Kamineni Institute of Medical Sciences

    thank you for sharing your experience. .

  • Where can I find a free software for 1D inversion of TDEM measurements?
    I´m an electrical engineer specialized in electrical grounding, and I need to extract a horizontal layered model of ground resistivity from TDEM measurements for a grounding design.
    Amin Esmail Khalil · University of Science Malaysia

    Dear Paolo, would you please tell me whether Beowulf is doing well or not.  I actually need free software for 1D TDEM modeling but all I tried was not good.

  • Alejandro R. Silva added an answer in Export:
    To which extent LNG today considering its price can become competitive on three major gas markets, i.e. EU, North American and Far East market?

    At this point due to the problems in EU gas supplies (developments between Russia and Ukraine) and the fact that these developments enhance the orientation of EU countries on the increasing security of supply LNG again becomes one of the important factors. Specifically, three gas market (the EU market, North American and Far East) have totally different gas prices. For example, USA gas consumers pay about 25-30% of the EU price and the Far East pay about 9 times higher price than USA customers. American gas exports, after export terminals in the United States become operational, as well as after loosening export controls oil and gas from the time of "oil shock" in 1971), for which the price competitiveness of LNG, to me it would depend on the source of supply and changes in the global oil market and the three regional markets natural gas under the influence of new players in the market LNG. American LNG will be competitive to current suppliers to the EU, Australia have a cost advantage in the markets of the Far East, India, Japan. Some market analysis show that importing LNG from the USA could have a beneficial effect for importing  countries in EU and Asia. At the moment, Europe is buying the USA LNG on the old continent's spot markets, where the prices are hovering now in the range of 320-340 USD per 1000 m3 of liquefied natural gas, and the price past summer was even lower, around 240-270 USD.

    Alejandro R. Silva · University of Buenos Aires

    Hi Darko,

    As I previously said this is not my field of expertise, but as an economist follow it.

    US Shale gas and oil reserves will begin to be operational by the end of this year and available for export next year. I understand that LNG price will decrease and this will favour the EU to cut it dependance on Russian Gas. EU and Russia Bilateral gas dependency became a very complicated issue, I would not recommend. It's for both, not only for the EU.

    It's said that shale gas from Argentina will be available in two years. As we have an important energy deficit today, it will not be available to export, but will substract LNG or NG from other exporters, i.e. actually we buy NG from Bolivia and import LNG from Qatar.

    In Argentina the NG duct system was adapted almost in no time to take LNG from Middle East, building a decompression station in Bahia Blanca, 1,000 km south of Buenos AIres. I don't know if this same station could compress the NG for export. The natural markets for argentine NG are Chile and Brazil. We have a gas duct connection to Chile and supplied them with gas for many years, but due to the dis incentive of energy production in our country, Chile had to import LNG. I don't know it they will be willing to take the risk of buying Argentine gas again. Brazil has discovered off shore oil fields, but don't know if there are important quantities of gas. The Brazilian NG market is the biggest in South America, and don't know if Argentina would be a reliable supplier. They import NG from Bolivia, at very competitive prices, but I wouldn't rule out eventually the purchase of Argentine NG to avoid a "bilateral dependency" with Bolivia.

    If markets work correctly, there would be a decrease in the price of NG and LNG, and there "should be" a tendency for prices in different markets (US, EU and Asia) to get equal. Just a tendency. Regulations, market size, transportation costs have differential impact on prices. What specialist say is that Energy prices will tend to decrease, with the full exploitation of Shale gas and oil fields and with the increase in the interest rate by the US Federal Reserve next year.

    I hope this "non specialist" information is useful to you.

    Rgds.,

  • Does infinity exist or it is a product of human mind?
    What is the philosophical explanation of infinity?
    Vitaly Voloshin · Troy University

    Isn't it only the model in our mind?

  • Is the concept of field the proper way to describe physical processes?

    What is a field? Everywhere around a 'source' of the field, if we put a 'test particle', then a 'force' will be applied to it, coming from the source.
    This definition has a critical drawback:

    • if you calculate, using volume integrals, the total energy of the field , then you will find it infinite. Is this acceptable?

    On the contrary, there exists the interaction from a distance view, where a force is applied to the test particle only when it is being present in the neighborhood of the source. So, we have not any kind of infinite energy here.
    Which approach do you believe that is correct and why?

    Oscar Chavoya-Aceves · Glendale Community College, AZ USA

    The statistical interpretation of qm would be disrupted if we where to introduce something like a  time operatir in the formalism. The concept of mutually exclusive events is fundamental to the theory of probabilities and two events are mutually exclusive if they cannot both appear as the result of one and the same experiment: at the same time.

  • Holger Fey added an answer in Protocols:
    Can anyone give me suggessions about qRT-PCR?

    I would like to know if the reverse transcription reaction influence or not the DNA expression, in other way I would say which appropriate protocol to convert RNA to DNAc for real time PCR reaction, because i found many protocol with different time of incubation, could you suggest good and not expensive one, Regards.

    Holger Fey · University of Illinois at Chicago

    I've used Qiagen's QuantiTect Reverse Transcription Kit to get cDNA from RNA. The protocol includes a first incubation step to get rid of genomic DNA contamination in your RNA prep and then a simple and quick RT reaction setup. You start with 1 µg total RNA as input and then you're going to have to assume that during the reverse transcription all RNAs are written into cDNA retaining their respective proportions. The primer solution in the Qiagen kit however is a mix of oligo d(T)s and random multimers, so in my case where I transcribed RNA that didn't have a poly(A) I used a different primer mix (random hexamers from Roche) instead to not disproportionally over-amplify poly(A) bearing RNAs.

  • Jitendra Mishra added an answer in Simulink:
    How do you do snr vs input power analysis in Matlab simulink?

    I am working on Adaptive sigma delta modulator in matlab simulink. I need to do snr vs input power analysis in simulink model. I am not able to find the build in block. Please help me to do the analysis.

    Jitendra Mishra · Gyan Ganga Institute of Technology and Management

    There is some block available in simpowersystem toolbox like mean, RMS.... other measuring components you can use it.

  • Mohammed Yaro added an answer in Streptococcus:
    What are the recent vaccine formulations which are effective against Group B streptococcus in pregnant women ?

    What are the recent vaccine formulations which are effective against Group B streptococcus in pregnant women ?

    Mohammed Yaro · Biotechnology and Nuclear Agriculture Research Institute

    Hi Ali,

    I have no worked on this group of streptococcus, but kindly see this wonderful article by Madhi et al. 

    Vaccine. 2013;31(Suppl 4):D52-7.

  • Jose M Fernandez added an answer in MUPS:
    How do you evaluate single MUPs during needle-EMG in proximal muscles (e.g. gluteus med, supraspinatus)?

    During my investigation it was often hard to discriminate one single MUP in muscles mentioned above (e.g. also in iliopsoas). Do you have the same experience and how do you deal with the question to evaluate MUP amplitude in these muscles?

    Thank you in advance!

    Jose M Fernandez · Conselleria de Sanidade

    Your question suggests that you are working in Clinical EMG. If so,  the answer to your question depends very much upon the equipment you use. Both Key Point and Sinergy equipments have the Multi MUAPA (multi Motor Unit Action Potential Analysis) and the others most likely will implement this program too. The advantage of this program is that you can collect  25-30 MU Potentials in 5-10 minutes. In addition, there are reference values (amplitude, duration, number of phases, etc) of  most of the muscles commonly  examined  in clinical routine. You can do it also record and measure individual  MUPs but this technique is time consuming and cumbersome. 

    The most relevant parameter (variable) is the mean duration of the PUM and stability of the components of the MUP. Changes in amplitude are less useful. The MUPs must sound crispy; by slightly repositioning the needle you can get better potentials.  Concerning the technical aspects, indications and procedures,  I would advise you the Jun Kimura text (Electrodiagnosis in Diseases of Nerve and Muscle, Oxford University Press, 4th edition, 2013). If you are planning to do Single Fiber EMG the book is Single Fiber EMG by E. Stalberg, J Trontelj, and Don Sanders, 3rd Edition,2010. Edshagen Publishing House, Fiskebäckskil, Sweden (WWW.SFEMG.INFO ). You ALSO can visit  Key Point Club (it´s very easy to find it in Google.) Good  luck

  • How can I find the orthologous gene list of Triticum aestivum and Arabidopsis?

    Dear all,

    How can I find the orthologous gene list of Triticum Aestivum and Arabidopsis?

    Some databases like www.pantherdb.org can find it but it can not find for a gene list.

    Luis D Maldonado-Bonilla · Instituto Potosino de Investigación Científica y Tecnológica

    You can seach for orthologous in Ensembl Plant:  http://plants.ensembl.org/index.html

     I've used it, very nice tool.

    Good Luck

  • Adam B Shapiro added an answer in Allosteric Site:
    How can I generate a pharmacophore model based only in structure (receptor)?

    I'm entering into this field of Drug Design (I'm really new but this field promise a lot for my desires) and, we're aiming to design somei nhibitors considering allosteric sites of an interesting protein. This allosteric sites are kind of new (discovered 3 or 4 years ago), the residues were described with fpocket software. Is it possible to generate a pharmacophore model of these allosteric pockets based on the residues and the potential interactions that could be made with them? There is a lot data about competititve inhibitors that work in other non-allosteric pocket, QSAR studies, Pharmacophore modelling and so on, Just add to expand my explanation..

    Also, no inhibitors or compounds were described yet related to these pockets. How could I start? I would really appreciate to dialogue and exchange some ideas about this, I really love this topic!

    Adam B Shapiro · AstraZeneca

    A pharmacophore model is based on the structures of known ligands. Since there are no known ligands for this pocket, another approach is needed. Virtual screening is an option. If you do that, make sure you have an experimental plan for testing the selected ligands. Are you able to do real screening?

  • Why is the wavelength of visible light big compared to the dimensions of an atom?

    The wavelength of visible atoms is about 5000 times bigger than the size of atom. From classical electromagnetic theory we know that the dimension of the emitted radiation is of the order of magnitutde of the antenna.

    Saman Alavi · University of British Columbia - Vancouver

    There are electromagnetic waves with different wavelengths. X-rays have wavelengths similar in scale to atomic dimensions.

    The only reason visible frequencies are special is that they are detectable by the human eye. The reason why these particular wavelengths are visible to human eye, is that they have a size comparable to structural features of the cells of the human retina.

    The reason why human cells have to be so large and must have dimensions so much larger than individual atoms is expressed very eloquently in Erwin Schroedinger's book "What is Life". The size is cells is large to minimize the effect of fluctuations in the environment.   

  • Sathiesh Kumar added an answer in Embedded Systems:
    In C program for Embedded System. Which one is better? And Why?(No threading used)

    200lines of main function or the main function with many branching functions reducing the number of line to 10-20...

    Sathiesh Kumar · Indian Institute of Technology Madras

    In your code, if the repeatability is more then it is better to go with functions or else it is better to go with single main function...

  • Puvanan Karunanithi added an answer in Alginate:
    Can anyone help me to interpret my SEM picture. I encapsulate msc for 21 days in a scaffold. Do these pictures show differentiated MSC??

    I encapsulated MSC in alginate beads.

    Puvanan Karunanithi · University of Malaya

    Thanks, Dr Balaji, Yohan Farouz.

  • Mohammed Yaro added an answer in Drug Resistance:
    How do you safely work with drug-resistant bacteria ?

    Drug-resistant bacteria pose great threaten to the public but also to the researchers who are working on them. Do you have any experience to deal with those super-bugs when working on them? How do you protect yourself? 

    Mohammed Yaro · Biotechnology and Nuclear Agriculture Research Institute

    Hi Daniel,

    You definitely need the right and standard facilities to begin with. Besides, the correct Laboratory classification, personal protective equipment (eye google, Lab coat, gloves etc.) and of course appropriate Bio safety chamber/cabinet. But, most importantly the  tragic recent lessons of Ebola has reminded us of the need for us to exercise extreme caution in order not to breach any of these standard protocol. Our overall attitude is very key in ensuring our protection.

  • Kenneth M Towe added an answer in Political Action:
    Climate mitigation action?
    What must happen for people to reduce and remove greenhouse gases from our atmosphere?
  • Saman Alavi added an answer in Gromacs:
    With regards to Gromacs Radius of gyration, how do I analyse the data?

    Does anyone know how to analyse the plot obtained from gyration? I know what it means but I'm not sure how to use this measure or interpret data? I run MD for a protein in complex with DNA.

    Saman Alavi · University of British Columbia - Vancouver

    The radius of gyration gives you an "effective radius" for the molecule or complex. It can tell whether the molecule is in a globular folded state or open denatured state. For example, you can compare the radius of gyration of the protein without the DNA or complexed to DNA. This can give you a very rough measure of how the protein has changed shape upon complexation.

  • What assays can be used to analyze nuclear, membrane and cytoplasm proteins?

    I want to know the assays that we can use to analyze protein from nucleus and membrane cell? and how about protein that are separated from cell, can we detect it?

    M. Ricky Ramadhian · Lampung University

    Thanks for your answer Mr. Subash Chandra Malik, Mr. Gabriel López-Velázquez, Mr. Steingrimur Stefansson,

    @Mrs Fatchiyah Fatchiyah , i am still writing the draft not yet become proposal..thanks for your kindness..

  • Oscar Chavoya-Aceves added an answer in Metrics:
    Is Euclidean distance appropriate for high dimensional data?
    When and why is it appropriate? And how to define a metric for high dimensional space?
    Thanks for your answers in advance.
    Oscar Chavoya-Aceves · Glendale Community College, AZ USA

    The quadratic norm has the advantage of being differentiable. When solving problems in parametric statistics it is perhaps the best choice. There are cases though where a differentiable metric is not required, or it doesn't even make sense (that is the case of sequence alignment, to give an example).

  • Hu Pei added an answer in Lipase:
    How does remnant-like lipoprotein enter into macrophages and how is it then degraded?

    How does remnant-like lipoprotein (greatly differ from oxLDL, mainly comprised of VLDL and LDL) from aged apoE-/- mouse enter into macrophages, by receptor or endocytosis? While it is taken up by the cells, is it mainly degraded by the lipases in cytosol or in lysosomes? Which pathway is the dominated?

    Hu Pei · Wuhan University

    very thankful to Regina Wikinski, I am really a new player on RLP, now another question appears, how do you evaluate the role of another scavenger receptor, SR-BI, on transportation of RLP, as it have a dual role on lipid transportation.

  • Any papers out there on arsenic concentration in Kenyan Rift valley soils?

    very suspicious values from my lab analysis --which is accredited

    Solomon Omwoma · Beijing University of Chemical Technology

    Broadening your search to have the key words 'arsenic in Kenya soils' would give you a broader perspective especially in Kisumu and Migori where arsenic is mined together with gold.

  • Saman Alavi added an answer in Software:
    What is the best software and user friendly software for MD simulation?

    I am newbie in this simulation, so i would like to see the simulation for Protein-ligand..

    can anyone here suggest which software that is easy to use for newbie?

    Saman Alavi · University of British Columbia - Vancouver

    In addition to the excellent programs mentioned above, you can also consider AMBER. There are a number of easy to follow tutorials for performing specific tasks. After following the Introductory Tutorials, you should be able to do the simulation you mention.

  • Arkady Bolotin added an answer in Physics Theory:
    If the wave functions of the Universe were infeasible, would they correspond to any element of physical reality?

    Does it imply that if the theory did not allow calculating values of the given quantity in reasonable time, then this theoretical quantity would not have a counterpart in physical reality? Particularly, does this imply that the wave functions of the Universe do not correspond to any element of physical reality, inasmuch as they cannot be calculated in any reasonable time? Furthermore, if the ‘computational amendment’ (mentioned in the paper http://arxiv.org/abs/1410.3664v1) to the EPR definition of an element of physical reality is important and physically meaningful, should we then exclude infeasible, i.e., practically useless, solutions from all the equations of physical theories?

    Arkady Bolotin · Ben-Gurion University of the Negev

    Dear Hans,

    What the wave function stands for strongly depends on whom you ask this question. Some would answer you that it represents information in the mind of the observer, i.e. a measure of our knowledge of reality. But others would insist that the wave function really exists, i.e., it must have an objective, physical existence.

    Withal no one would argue about what the wave function describes: It describes the quantum state of a system and its evolution over time. And this makes it possible to assign the wave function to the whole Universe.

    For example, Hartle and Hawking in their celebrated paper “Wave function of the Universe” describe the quantum state of a spatially closed universe by a wave function, which is a functional on the geometries of compact three-manifolds and on the values of the matter fields on these manifolds. This wave function obeys the Wheeler-DeWitt second-order functional differential equation.