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.

Browse Topics

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
  • Leonard A Smith added an answer in Chaos Theory:
    How do I determine the dimension of homoclinic manifold?

    Homoclinic motion is rather important due to the fact it suggest the chaos in the sense of Smale horseshoe. How do I determine the dimension is the foundation to study for homoclinic motion in the high dimension case. What the  general steps to determine its dimension. 

  • Rami Ben Haj-Kacem added an answer in Econometrics:
    What is the interpretation when explanatory variable is in logarithm and dependent variable is growth rate?

    E.g dependent variable(y) is growth rate of company profit and explanatory variable is logarithm of advertising expenses. And I am analysing the effect with panel of 500 firms and 

    coefficient is say 0.50, then what is the implication for given companies, like how we can write interpret difference between top 25 percentile companies and bottom 25 percentile companies.

    Rami Ben Haj-Kacem · University of Carthage

    Since the derivative of the log can be assumed as growth rate, I agree with Eva that the coefficient has to be considered as elasticity.

  • Kar-Weng Chan asked a question in Shooting:
    Toxic / lethal range - needs to be accurate?

    Accurate determination of some drug in the therapeutic range is indicative of the patient being under medication. If someone dies from taking too much of this drug, the level will shoot beyond the therapeutic range. So is it important to quantify toxic / lethal values accurately since it doesn't quite matter how high it is as long as it is outside the therapeutic range. Any sensible views?

  • Gunawan Indrayanto added an answer in Plant Extracts:
    How can I get the highest yield in plant extraction?

    Hi,

    Could you please tell me what is the best solvent which gives the highest yield in extraction of secondary metabolites from plants? and what is the best way: decoction, maceration, soxhlet, etc?

    I am trying to extract my plant in methanol or water, I want to know what is the best solvent: MeOH or water or a mixture MeOH/water? and what kind of compounds we could find in each extract?

    Thank you in advance.

    Gunawan Indrayanto · Airlangga University

    I agree with Miguel, I also usually MeOH; after that, if it is needed  you can fractionate te MeOH extract using hexane, CH2Cl2, and acetone. With MeOh you can have almost all metabolites (for metabolite profiling in plants usually I used MeOH); but for decoction I think you should only water.

  • Rocco Piazza added an answer in Bioinformatics:
    I would like to perform DNASeq on patient material, but do not have germline material. Is there a (bioinformatic) way to determine somatic mutations?

    I would like to perform next generation DNA sequencing on a hematological cancer. As said in the title, l don't have any germline material of the patients. Does anyone know a (bioinformatic) way to dissect germline from acquired aberrations? Thanks already for your help!

    Rocco Piazza · Università degli Studi di Milano-Bicocca

    Hi Julia,

    although the suggestion of Albino is ok (you can also try the newest dbSNP, which incorporates the 1000g data), the problem raised by Michael is critical. Even filtering with dbSNP you will likely end up with a long list of variants. Then, discriminating between rare SNPs, somatic drivers and somatic passengers will be extremely challenging/impossible, unless you're only interested in the identification of already known oncogenic lesions. Are cancer cells available or just DNA? is it a myeloid or lymphoid leukemia?

  • Alok Kumar Soni added an answer in Protein Extraction:
    How does one calculate the concentration of a fraction eluted from a size exclusion column chromatography?

    I am involve in protein extraction and purification  from a human tissue. My protein of interest was detected by a dot blot and I want to use Direct Elisa to check it as well.

    Alok Kumar Soni · Defence Research and Development Organisation

    i also used BCA method for detedtion of protein of interest eluted from NI-NTA column, this is very simple and precise method.

  • Davron Ishnazarov asked a question in HDI:
    What empirical model to use to estimate impact of Official Development Assistance (ODA) on Human Development?

    Most of the studies implemented fixed effect or GMM due to the existence of estimation issues. Due to the nature of variables such as HDI and ODA both of the methodologies can be criticized or favoured. 

  • Rajat Sharma added an answer in Membranes:
    What is the weight range for immobilization of enzyme onto eggshell membrane?

    Most of the articles only state using eggshell membrane pieces but they didn't explain how much did they used for the immobilization.

    Rajat Sharma · Indian Institute of Technology (Banaras Hindu University) Varanasi

    Can you please tell me if amylase and cellulase will work on this glutaraldehyde activated eggshell membrane. If not, what might be the possible reason?

  • Christine Bang asked a question in Interaction:
    What does it mean by "There was a significant interaction between the time and the groups (P<0.001)"?

    I couldn't get my head around to interpret this sentence in a medical journal. Could someone explain this sentence a bit further?

    If I explain the background of the study a bit, there are 3 drug groups and and the graph  presents "mean VAS score (mm)" on y-axis and "Duration of tx (weeks)" on x-axis. I want to know whether the "a significant interaction between the time and the groups" can be interpreted as "the decreasing trend of VAS score in each drug is significant at each time of measurement". I'm attaching the graph for a reference.

    Thanks heaps! :)

  • David Aguado-Llera added an answer in PC12 Cells:
    How should I perform anti alpha-synuclein western blots?

    I am working with PC12 cells and. My problem is that when I perform anti alpha-synuclein Western Blots, the signals of this protein are never consistent with each other, even when I run duplicates of each sample. Is it because the protein is aggregated?In this case, what should I do?Should I sonicate my samples?Or make the lysates in a special buffer?

    David Aguado-Llera · Universidad Miguel Hernández de Elche

    Maybe you can make some tests adding some Urea or Guanidinium chloride to the sample buffer. I don't know if any of them get stucked to the blotting membrane, but it may be a solution to aggregation. You should get rid off the chaotropic agent when you transfer the sample to the membrane, but I am not sure of it. I think it is worth to give it a try.

  • Sarah Becker added an answer in Oxidative Stress:
    Please teach us how to detect oxidative stress using CellROX reagent?

    Does anyone have experience with the CellROX Green reagent for oxidative stress detection? We are trying to detect oxidative stress in cells(live or fixed) in 35mm plastic dish.

    Unexpectedly, the cells treated with ROX reagent gradually become to express strong signals while we observe the cells using fluorescence microscope. This unknown strong signals are detected in all cells which are exposed to excitation ray.

    H2O2 treatment is done for 4 hours. The last 30 minutes was incubated by adding Cell ROX Green(5uM).

    Sarah Becker · Catholic University of Louvain

    Hello,

    maybe you can try roGFP2 ?

  • Sree Gayathri added an answer in Drug Release:
    In drug release calculations, does dilution factor have any role in it?

    nanoparticle drug release

    Sree Gayathri · University of Science Malaysia

    Thank you so much for your response Krishna.Here, 10mg of nanoparticles loaded with drug were dissolved in 2 ml of pbs buffer in dialysis bag. The external media is 10ml of PBS buffer. Do we need to include this ( 10ml) external media in drug release calculation? *Urgent help is needed*

  • Vijay Jayaraman added an answer in Phenotype:
    What decides the kind of regulation for a particular biological function/phenotype?

    Regulation of a  biological function can be at transcriptional, translational or at the protein level (PTM or allostery). What are the constraints imposed by the phenotype that selects the nature of its regulation? Is there any generalisation that we can draw?

    Vijay Jayaraman · Jawaharlal Nehru Centre for Advanced Scientific Research

    Dear Carrasco, Thanks for the information. Can you send me any references wherein such a pattern is observed in any signalling pathways?

  • Vladimir Shatalov added an answer in Theoretical Chemistry:
    How can I get the average populations of excited states from Molecular Dynamics simulations (ES-NAMD)?

    I'm new to excited state non-adiabatic molecular dynamics. I'm wondering if there're techniques to get average population of different excited states from hundreds of trajectories. If there are some references, give me some advice. Thanks a lot.

    Vladimir Shatalov · National Technical University of Ukraine Kiev Polytechnic Institute

    The average population of different excited states depends only on the temperature of the system and follows by Boltzmann's or Gibbs' rules for low temperatures. If your system consists of a few particles you cannot introduce the temperature and if the system is also open it is doubtful to introduce the average populations of excited states at all.

  • Luis Miguel Gaspar Venancio added an answer in Refractive Index:
    How can I compute front focal length of cemented doublet lens from BFL?

    I can understand the Front focal length of Cemented Doublet lens will be the same with BFL if each parts of lenses were consist with same material(e.g. SF10).(lenses are surrounded with air)

    But I think that if each part of doublet lens had different material,(e.g. Lak21 and SF10) then the BFL and FFL will become different. 

    Then how can I calculate the FFL from BFL, EFL and refractive index? (Without Raytracing)

    Luis Miguel Gaspar Venancio · European Space Agency

    Oups, small typo I meant : EFL = BFL for (very) thin lenses.

    Anyway, keep in mind that the FFL, BFL and EFL relationships are valid only in paraxial optics. It is enough to have a first order knowledge of your system but not much more.

  • Rene Schade added an answer in Cohort Studies:
    How do I identify confounding factors in a cohort study measuring behaviour change?

    I am planning to conduct a cohort study in the community to measure uptake of an intervention and measure change. How do you mitigate against the confounding factors in such a study and ensure 'uncontaminated' results?

    Rene Schade · Erasmus Universiteit Rotterdam

    Dear Job Wasonga, Dear All,

    In a prospective setting, when randomizing communities, or to reduce contamination risk, ie, to prevent the control group to get exposed to the intervention, we might want to think about cluster-randomized trials. Please find relevant articles in the following links:

    http://www.futuremedicine.com/doi/abs/10.2217/cer.14.21

    http://www.bmj.com/content/345/bmj.e5661

    http://www.ncbi.nlm.nih.gov/pubmed/17136746

    Please let me know if trouble with viewing the full text.

    Wishing you a nice day, René

  • Ger Koper added an answer in EES:
    What is the difference between units kj/kg.k and kj/kg.c?

    hi friends,

    Are two units kj/kg.k and kj/kg.c equal?(about unit of entropy)
    why?
    I got in trouble for writing code in the the software EEs.

    Regards,

    ali

    Ger Koper · Delft University of Technology

    Assuming you mean kJ/(kg K) and kJ/(kg C), where K stands for a unit on the Kelvin temperature scale and the C for a unit on the Celsius temperature scale, the answer is yes because the Celcius and Kelvin scale have the same unit but different zero points.

  • Pratima Kochhar added an answer in RNA Concentration:
    Formula for converting RNA amount to no of copies?

    please help me with the formula for converting RNA concentration in ng into no of molecules/copies, from where and how it is derived.

    Pratima Kochhar · Tohoku University

    why we are using 6.022x10*23 and in denominator 1x10*9 

  • Sriram Sundar asked a question in Hypermesh:
    Is it possible to model a connector where I should be able to define Force vs Displacement relationship in ABAQUS?

    I am using hypermesh to develop the model.

    1) If I mesh the model in Hypermesh, with which option I should define the geometry of the connector element [As far as I checked, there are gap, bar, spring rbe3 and other 1D elements. Connector has 4 options namely spot, seam, bolt and area.] Which option to use ?

    2) If I use CAE, using which option I can define the displacement vs force relationship ? [I defined a basic axial wire and gave elasticity as the behavior option. However, I couldn't add the displacement data in the same dialog box.

    3) Can I use the same axial type connectors for explicit 3d drop analysis ?

    Thanks for your help in advance !!!

  • Marcus Hanley asked a question in Cloning:
    To anyone with experience of In-Fusion cloning......?

    Having previously and successfully used the In-Fusion cloning kit I'm having real issues with my current round of cloning.  I have a number if 2kb-ish fragments that I'm trying to insert into the EcoR1 site of the pEF-IRES bicistronic vector.  The inserts amplify without issue, the vector linearises without issue, I even see a band of the correct size after the 'ligation' BUT.......no colonies!  This is using both the Stellar and and TOP10 cells.  Controls work fine.  All primers designed in direct accordance with the instructions.  I've checked the sequence of my plasmid prep.  I've tried gel purification verse Cloning enhancer for the amplified fragments (which they say ges rid of template.....which it doesn't......and I don't see how it would....as an aside, can anyone give me the heads up on this, have I missed something very basic?) but to no avail.  So........anyone had any similar issues who could pass on their wisdom?

    Desperate enough now to consider any ideas!!

  • Hibatullah Stetieh added an answer in Urban Design:
    Can anyone suggest resouces that outline urban design principles for typical streetscapes and housing configurations ?

    I am investigating urban design principles for typical streetscapes and housing configurations.

    Hibatullah Stetieh · University of Jordan

    Dear Heath

     Responsive Environments (Sue McGlynn, Graham Smith, Alan Alcock, Paul Murrain, Ian Bentley):

    This book clearly demonstrates the specific characteristics that make for comprehensible, friendly and controllable places; “Responsive Environments” – as opposed to the alienating environments often imposed today. By means of sketches and diagrams, it shows how they may be designed in to places or buildings. This is a practical book about architecture and urban design. It is most concerned with the areas of design which most frequently go wrong and impresses the idea that ideals alone are not enough. Ideals must be linked through appropriate design ideas to the fabric of the built environment itself. This book is a practical attempt to show how this can be done. Explore what is meant by the concept of a ‘responsive environment’. The illustrated step-by-step guide shows you how to achieve a ‘responsive environment’ in real-life design.

    http://designingthelandscape.com/2012/08/28/10-books-to-read-in-your-third-year-of-landscape-architecture/

    you can find a copy on : academia

    http://www.academia.edu/6243081/Ian_Bentley_et._al_-_Responsive_Environments

  • Rocco Piazza added an answer in Sanger Sequencing:
    Can I do Sanger sequencing for bisulfite converted product having size of 350 bp?

    Can I do Sanger sequencing for bisulfite converted product having size of 350 bp? I have bisulfite converted the DNA. I want to study only promoter region of a gene. I made three bisulfite sequencing primers from the promoter region of the gene. The product size is maximum of 350 bp. Can I do Sanger sequencing of such a short product size? Or shall I do pyrosequencing? 

    Rocco Piazza · Università degli Studi di Milano-Bicocca

    It is, up to a certain extent. For instance, how heterogeneus is your cell population?  If you expect a condition of either 100% methylated or 100% unmethylated or 50-50 then using Sanger is perfectly fine. If you want to detect low levels of methylation (because for instance only a fraction e.g. 5-10% of your cell population is 'methylated'),  then Sanger is not the best choice and you should use alternative techniques, such as pyro or deep sequencing (NGS).

  • MANI GANESH added an answer in Column Chromatography:
    Could anyone suggest a suitable column for estimating Sod.Hyaluroanate?

    At present we are using Biosep-SEC-S2000 column for the purpose but the results were spurious every time can any can suggest some good column for analyzing/ estimating Sodium hyaluronate in its formulation using HPLC -PDA?

    MANI GANESH · Hanseo University

    Thank you so much sir for your suggestions. as our product is BP category hence we are supposed to follow British pharmacopoeia. we got the colour too by BP procedure but the calculation what they given is little confusable. if possible please give a detail for the factors they had given ( cs and cg)

  • Armando Nappi added an answer in Morphological Analysis:
    Please, does anyone have a suggestion concerning morphological techniques in digital image processing?

    Please, does anyone have a suggestion concerning morphological techniques in digital image processing?

    Armando Nappi · Museo civico di Storia naturale, Italy, Morbegno

    You can see this journal

    http://www.italian-journal-of-mammalogy.it/issue/view/405

  • Christopher. P. Brough asked a question in Pegmatites:
    What information is required to verify a new mineral identification?

    During some routine pegmatite mineralogy we came across an unknown mineral in association with the very rare-mineral 'fluorcalciomicrolite'. We no longer have the grab sample from which the thin section was taken but still have the thin section and have had the opportunity to analyse it quantitatively, along with some element mapping.

    The results confirm that our mineral is either unique or a second world occurrence of the recently discovered 'peterandresenite' but with high concentrations of Nb, presumably substituting for the Ta. The question is, what additional work can be done to confirm or publish the results bearing in mind all that we have is a normal 30 micron thin section of the mineral in question? 

  • Miyuki Mizuno asked a question in Pull-Down:
    How do I see how two different phosphorylation events of the same protein are connected?

    I want to determine how two different phosphorylation events of the same protein are interconnected to see if it regulates the stability of the protein and also see if there is any flux in translation lvls pertaining to circadian rhythm.  How would I go about that?

    Should I do a co-IP or GST fusion protein pull-down exp first?  Then western blot? etc.

    Thank you for any help that I can get to figure out this question.

  • Branimir Todorovic added an answer in Networked Control Systems:
    What are the best recurrent neural network training methods on-line?

    The use of the recurrent neural networks in control systems becomes more and more interesting subject, but that is based on the training method that we use , in control we need our training to be on-line and this is convenient for the applications that we are trying to work on , so what are the learning approaches in the dynamic neural nets " recurrent " and which ones are the best among them ? 

    Branimir Todorovic · University of Niš

    Hessian free algorithms are interesting and promising as a research area. However you should know that they will not work in sequential training scenario, training based on just one example at a time step. On the contrary the EKF, UKF, DDF etc. (Bayesian filters) are suitable for sequential training of RNN. And once again, it is very important to note that these algorithms generalize „teacher forcing“, which is very important, especially at the beginning of the training. In my experiments I usually obtain very good generalization after training sequentially only on 2000 samples.  „Quasi sequential training“ with Hessian free algorithms demands a sequence of mini-batches. And,  in order to estimate accurately enough the curvature of the criterion function, these mini-batches cannot be small (they cannot contain only one sample).

  • Subramaniam Sujatha added an answer in 1H-NMR:
    What is the 1H NMR chemical shift for acidic proton of fatty acids I (CDCl3 solvent)? Will it usually appear?

    Thanks in advance for your replies.

    Subramaniam Sujatha · National Institute of Technology Calicut

    Thank you all.................

  • George Dishman added an answer in Electrical Engineering:
    Is transmission of alternate electric currents having different frequencies possible in a single conducting wire?

    We are aware about transmission of electric signals in various frequency bands in a conducting cable/wireless transmission using modulation and demodulation. These signals can be separated at the end points. I would like to know whether transmission of alternate electric currents having different frequencies (for power cables) is possible in the same way. This concept will facilitate availability of electric powers at desired frequencies in the same power cable for running different electric appliances (at 50hz, 60 hz so on).

    George Dishman

    For widely separated frequencies at similar voltages, it wouldn't be too hard but mixing 110V with 6.6kV will give you major problems. Just attaching both to two primaries on a transformer will result in the 6.6kV being fed back into the 110V output of the other generator which will probably blow it up.

    As has been mentioned, you may also need to avoid say 60Hz signals appearing on the input of a load that expects 50Hz. While many devices will happily work from either, providing both will produce a 10Hz beat. That will seem like amplitude modulation of a 55Hz supply to the load and it would then need reservoir capacitors 6 times larger than the load designer expected. The Q required for filters would be achievable using small electronic devices (e.g. op-amps of switched capacitor filters) but to handle the power you would probably expect to use a passive solution and that is not achievable any a reasonable cost.


    A more practical solution may be to distribute a single frequency and change the output to what the loads expect using inverters.

  • Ivan Padlina added an answer in Rheumatoid Arthritis:
    What is the relation of lipid profile in Rheumatoid arthritis?

    Rheumatoid arthritis patients are potentially at higher risk to develop cardiovascular risk, but studies have shown reverse correlation of lipids and RA with different opinion. What is actual relationship and if lipids are low, how Statin helps in RA?

    Ivan Padlina · University Hospital of Lausanne

    I agree with Dr Cocco. Pro inflammatory conditions are the basis of CVD and RA is no exception. Studies in the past have shown that algorithm for the assessment of CVD risk (ex: SCORE) factors have the tendency of underestimate CVD risk in RA positive patients. That s why a specific SCORE score was developed. The paradoxus of dyslipidemia with decreased LDL titer must be handled with care imho.