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

  • Eduardo Cárdenas added an answer in 3' RACE:
    Can anyone help me troubleshoot 3' RACE?

    I´ve been trying to amplify a 4kb cDNA using the technique 3' RACE, but I´ve only been able to get smaller bands (less than 1 kb). The gene from which this cDNA comes has many splice variants, and I've made my best to make my primers specific for the functional transcript. Has anyone faced these issues?

    Eduardo Cárdenas

    I increased it to 4 mins.

  • Carlos Araújo Queiroz added an answer in Enthalpy:
    How do I find the enthalpy from DSC data ?

    I have DSC data (Temp Vs heat flow). I got one peak on the negative side of heat flow and two peaks on the positive side of it. How do I interpret it and how shall I find enthalpy from it.

    Carlos Araújo Queiroz

    The plot suggests that you may have some trouble with the calibration essay; it should match exactly the essay with the actual sample, in terms of materials, operating conditions, and thermal schedule. 

  • Peter Raynham added an answer in Programming Languages:
    What is the most common Unicode encoding used in programming languages implementation?

    It seems like different languages ended up using different encoding to support Unicode. I was wondering if someone here has a personal experience on the topic.

    Peter Raynham

    Sorry to give the answer "It depends" ... but it depends on what you want to do ... however UTF-8 is the default to prefer.

    UTF-8 is more durable, which means that more kinds of software can handle it. UTF-8 will be the better choice for programs that send/receive data to/from other programs, that read/write files to be shared with people on other systems, that use libraries including Unicode-unaware libraries like the old C 'string.h'. That is, UTF-8 a better choice for most programs that you may write.

    UTF-16 is more computation-friendly. If you program does a lot of string manipulation, UTF-16's 2-byte fixed-size character cells make it easier to do things like extract substrings, or get/compare/update individual characters inside a string by index. Unfortunately, if a string includes characters from the (lesser-used) supplementary code pages (which take 4 bytes each) then you lose the computation-friendliness.

  • Hanna Froebe asked a question in Cell Passage:
    Sf9 cells dying at passage 8: has anyone experienced similar issue?

    Sf9 cells at passage 8 starting to show poor growth, decreased viability; cells are basicly slowly dying;  No signs of bacterial contamination.This has repeated with 2 cell lots, taken from liquid nitrogen; up until pass 8 viability is over 98%; doubling time about 40 h.

  • Hendrika Vande Kemp added an answer in Caregivers:
    I am looking for instruments that measure emotional and spiritual distress for hospitalized patients. Do you have any recommendations?

    My research is looking to see if there is a correlation between functional status of a patient using Katz and Lawton assessments of ADL and IADL with emotional and/or spiritual distress of patient and/or caregiver.

    Hendrika Vande Kemp

    There is an article with a spiritual distress assessment tool at http://bmcgeriatr.biomedcentral.com/articles/10.1186/1471-2318-10-88

    The spiritual distress assessment tool: an instrument to assess spiritual distress in hospitalised elderly persons
    Stefanie M MonodEmail author,
    Etienne Rochat,
    Christophe J Büla,
    Guy Jobin,
    Estelle Martin and
    Brenda Spencer
    BMC Geriatrics201010:88
    DOI: 10.1186/1471-2318-10-88

    ©  Monod et al. 2010\

    Also related at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368768/

    BMC Geriatr. 2012; 12: 13.
    Published online 2012 Mar 29. doi: 10.1186/1471-2318-12-13
    PMCID: PMC3368768
    Validation of the spiritual distress assessment tool in older hospitalized patients
    Stefanie Monod,corresponding author1 Estelle Martin,1 Brenda Spencer,2 Etienne Rochat,1,3 and Christophe Büla1
    Author information ► Article notes ► Copyright and License information ►

    You can download this tool on the Springer website at http://link.springer.com/article/10.1186%2F1471-2318-10-88#/page-1

    Research articleBMC Geriatrics

    December 2010, 10:88

    First online: 13 December 2010
    Open Access
    The spiritual distress assessment tool: an instrument to assess spiritual distress in hospitalised elderly persons
    Stefanie M Monod 
    , Etienne Rochat
    , Christophe J Büla
    , Guy Jobin
    , Estelle Martin
    , Brenda Spencer

    Put "spiritual distress assessment" in your search engine and you'll find more on the same topic.

  • U. Dreher added an answer in Electrical Engineering:
    Is there any device which can control load current than the sanction capacity?

    Is there any device in electrical engineering which has the capability to release current from the utility side instead of absorbing current from the load side so that consumer will never draw more current than their sanction capacity? Load current limiting device?

    U. Dreher

    Overcurrent relays and load tripping are the more conventional approaches.

    Another (rather complex) approach is a "grid parallel" power supply: charging batteries when the local demand is low, feeding the local grid when the local demand is high. Thus, at the "official grid" connection point the current would not exceed the limit value whilst locally the load could be higher. Controls can be implemented by measuring the current at the grid connection point.

    Such devices exist (though I cannot point you to one), but this is surely the most expensive and complex solution.

  • Allen Spaulding added an answer in Ecology:
    I need to use R software (ape package) for studying biological evolution of Platycheirus sp. ?

    I have the DNA sequence of 20 species, and the data for all characters of these species like (thorax volume, proboscis length, wings and legs length, abdomen length, ........ect), my question is :
    1- which kind of file format I should use for interning the sequences in to R?
    2- After building the tree How can I connect between the character data that I have and the tree?

    Allen Spaulding

    Sure!  I will email you. 

  • Segun Oke asked a question in Mathematical Models:
    How do I calculate Sensitivity and Threshold analysis on Mathematical model of breast cancer ?

    When we are working on  different treatments of on breast cancer: thermotherapy, drugs ,surgery ,chemotherapy?

  • Amin Fathi added an answer in Botany:
    Whether the plant that grows in the mountains is resistant to all kinds of stress?

    Are these plants can be planted to crops? What are the advantages and disadvantages?

    Amin Fathi

    The natural ingredients are a lot of environmental conditions. why?

  • Ali Basheer Jubran asked a question in RID:
    What should I do to get rid of blood cells in the pharyngeal, and the dorsal aorta region for E10.5 embryos?

    I am interested in the phyrengeal arch arteries, and staining is affected by the presence of RBC's. How can I get rid of blood cells after dissecting embryos. I know that I can do perfusion with PBS into the outflow tract, but I am interested in knowing any other methods (if available). 

    Thank you 

  • Ahmed Mansour Alzohairy added an answer in RAPD:
    Is there any cheap software doing phylogentic analysis from RAPD images ?

    Dear Friends I am asking about any cheap software for doing dendrogram from DNA Images

    Ahmed Mansour Alzohairy

    We have developed some Egyptian software's for Gel-Analysis which are more accurate but it still under publications 

  • Allen Spaulding added an answer in Pathobiology:
    Bacterial Mutation Rates = How will Whole Genome Sequencing Affect Our Thinking?

    Bacteria change over time both quickly and slowly and both randomly and non-randomly.  Teasing this apart is problematic.

    Can the measurement of the mutation rate of a single gene be meaningful outside the context of the average mutation rate of the whole genome?  Can we make assumptions about the mutation rate of a single gene based on the average whole genome mutation rate?

    Can we even measure the whole genome rate even with next gen sequencing technology?  This would assume that if you sequenced the same batch of genomic DNA a hundred times you would get pretty much the same answer 100 times.  Since I have yet to see any WGS tech provider tooting this particular horn I would assume no.

    But even if the sequencing tech was 100% accurate over 2 million bases, is any given sampling of bacteria homogeneous,  even from a single well isolated colony?  It depends on how the actual whole genome mutation rate compares with the human scales of sampling.  It depends on whether bacteria have mechanisms for generating hot spots.  It depends on whether bacteria have regulatory networks that can modify the mutation rate. Lastly it depends on known and unknown selection pressures and the conditions you grow your bacteria under. Rich vs limiting media is only scratching the surface.

    Researchers like to focus on genetic drift because it seems to be the simplest to measure, but who can say how much selection has been applied to any given gene.  Even untranscribed DNA can have many functions, much as punctuation functions in language.

    In pathobiology, random mutation may play a role over time, but it is probably too slow to be biologically relevant for bacteria competing for space on hosts, except with regards to tuning regulatory networks for adaptive responses to host condition.  Bacteria are much more likely to acquire competitively advantageous genes by theft wherever they are exposed to new genetic material.  How much of all the restriction and DNA modification machinery is dedicated to defense and how much to theft ?

    What is known is that at least some bacteria are naturally competent.  Next Gen WGS sequencing could answer the question of how good thieves bacteria really are.

    Allen Spaulding

    Remember that genetic drift is not just a function of selection (or lack of it), sampling error in population bottlenecks is also an agent of genetic drift.  When someone says the mutation rate of a lineage is high, it may simply be that the ecology of the lineage is such that the substitution rate is high among a lot of internal lineages undergoing frequent bottlenecks.  Without getting bogged down in a discussion of the meanings of the terms mutation, substitution, population, or lineage, the point is that the rate of DNA change can be a function of the ecology of the OTU. 

  • Axel Chu asked a question in Fibroblast:
    What markers should I use for cardiac fibroblast?

    I've been using Thy1(CD90) but its not working so well. Are there any other markers for cardiac fibroblast out there that is effective? 

  • Robert Kiss added an answer in Oncology:
    Clinical Phase II to Phase III failures in oncology?

    I am requesting the help of the RG community to provide me with recent (no older than 5 years) articles (from very high and only from very high ranked journals) clearly

    1) indicating how many and

    2) why

    so many positive Phase II clinical trials in oncology die during Phase III.

    I am quite new on RG ... but I already saw that "several" RG members are responding to questions like mine "why are you not making your biblio search by yourself ...".

    I did it but I am not convinced at all that I actually have the best articles in this field.

    Thank you for your time and attention.


    Robert Kiss

    It seems to me that "die" means "end".

    Your responses rephrase my question? But without providing the articles I request.



  • Céline Caseys added an answer in Mass Spectrometry:
    I have a plant sample and want to find out the phytochemical constituent of its dried leaf. Is LC/MS of crude extract be right technique?

    I want to do phytochemical screening of the plant. will lc/ms be the right technique to do it from crude extract. how to interpret LC/MS data?

    Céline Caseys

    LC-MS will give you insights, but the phytochemical profile will depend on the extraction (e.g. solvent) you use. Do you have a specific family of compounds (for example flavonoid, terpenoid) that you want to screen in particular?

  • Beatriz Goñi added an answer in Karyotyping:
    Does anyone have experience with Karyotyping in Drosophila cells? Could you share any tips and/or protocol?

    I need to determine the karyotype of a Drosophila virilis cell line and have some problems identifying the Colcemid incubation time to get nice synchronization, cell density, and method (cytospin vs "drop").

    Beatriz Goñi

    Do you need to use Formaldehide? suppose for inmunonanalysis ??

    Thinner chromosomes can be obtained (probably by treating cells with a shorter time  with colcemd (or less concentrated...).

     To get separated chromosomes, need to treat with hipotonic solution. Iin regular chromosome preparation, tissues are incubated in an hipotonic solution (time and grade of salt depends on the tissue), I think it can be very short in cell culture (few minutes...??)by diluting the same tissue culture media (with or without colcemid).

    Try, do not give up. The starting point of mantaining healthy cell culture is fundamental.

    Second, with a simpler method monitor cell conditions, before fixing with FA.

    Try just to get step by step. A rapid staining method to adjust the conditions of mitotic arrest and chromosomes elongation is to visualice cells (in mitosis) with a rapid method.. Do you read in spanish?

    I made my own method based (simplifying the method of Ashurner).

    After hipotonic I will simply fix the tissue in 60% acetic acid FRESH preprared (spinned gently? )drop one dro on the slide + one small drop of orcen acetic acid 2% and a smal coverslip on it. It will let you detect stained chromosomes.

     Orcein (acetic acid) solution precipitate. You can spin 1.5 ml  (5min x 7000rpm) take the supernatant colorant with a 1ml hypodermic syringe (tale out the jeringe, at first). And you can keep the precipitation free orcein for further experiments.

    Good luck, any other question write to me, Yours Beatriz

  • Peter Harremoës added an answer in Complexity:
    Are there 2-D extension of real number like complex numbers that is non-commutative?

    Quaterion is non-commutative but it is a 4-D type hypercomplex number. We also have Dual Numbers and Hyperbolic or Perplex Numbers but they are still commutative. Are there other 2-D hypercomplex numbers similar to complex number but non-Abelian?   

    Peter Harremoës

    Sorry, you are right it is not bi-linear so according to standard definitions it is not a product. I am too used to products so I overlooked that the composition was ab+cd rather than ac+bd. Anyway, since it is not bi-linear it does not define an algebra and the discussion whether it is a field or not becomes irrelevant. 

  • Bekk Okk added an answer in Tcl Scripting:
    Dv-hop tcl script not running ?

    i am working on dv-hop localization algorithm. i have implemented the protocol in ns2 but when m running its tcl script, it shows error if any one have error free dv-hop tcl script then please give it.  it will be great help for my research or else if any one can solve this error i will be thankful, error is: (num_nodes is set 9 (_o15 cmd line 1) invoked from within "_o15 cmd addr" invoked from within "catch "$self cmd $args" ret" invoked from within "if [catch "$self cmd $args" ret] { set cls [$self info class] global errorInfo set savedInfo $errorInfo error "error when calling class $cls: $args" $..." (procedure "_o15" line 2) (SplitObject unknown line 2) invoked from within "_o15 addr" ("eval" body line 1) invoked from within "eval $node addr $args" ("default" arm line 2) invoked from within "switch -exact $routingAgent_ { DSDV { set ragent [$self create-dsdv-agent $node] } DSR { $self at 0.0 "$node start-dsr" } AODV { set ragent [$self cre..." (procedure "_o3" line 14) (Simulator create-wireless-node line 14) invoked from within "_o3 create-wireless-node" ("eval" body line 1) invoked from within "eval $self create-wireless-node $args" (procedure "_o3" line 23) (Simulator node line 23) invoked from within "$ns node" ("for" body line 2) invoked from within "for {set i 0} {$i < $val(nn) } { incr i } { set mnode_($i) [$ns node] $mnode_($i) random-motion 0 } " (file "/home/mahnoor/Downloads/dvhop2d/dvhop_802_11.tcl" line 47)

    i have attached the code. Please reply soon.


    Bekk Okk

    maha noor,

    i don't know anything about tcl script  but i think that num_nodes is set 9 may  means that y have configure something to be from 0 to 8 nodes while y are using 9th node.

  • Hendrika Vande Kemp added an answer in Existentialism:
    Does anyone by chance have e-book of George Cotkin "Existential America"?

    I need it for my research

    Hendrika Vande Kemp

    Google books indicates there is no ebook available. Too bad!

  • Siraj Maeen added an answer in Data Mining:
    what kind of data mining and machine learning algorithms can I use for my research work?

    Dear All, I need little help at starting my research work, I want to develop knowledge based event detection system from social media big data based on text messages and spatio-temporal information, I mean the system should have ability to tell about what is happening? what and where? in some region for example in London, The system should tell about for example emergency situation, fire, earthquake, traffic jam, raining, disease, volleyball or football match etc.

    so my question, is it possible to detect such things from social media? for example from twitter.

    if yes, then what kind of data mining and machine learning algorithms which i have need to use it for starting my research work? please can anyone help me in my question. Thank you in advance for your answer.

    Best Regards,

    Siraj Maeen

    Dear Philippe, Thank you very much for the detail reply. I checked SPMF and I have started studying. Thanks  

  • Peter Mathew added an answer in Curing Temperature:
    What is the time and curing temperature required for obtaining PVDF film?

    I am trying to make PVDF thin films. I've used DMF/Acetone as solvents. What is the curing temperature and time required to obtain the films?

    Peter Mathew

    @Haider: Time required to obtain film after curing

  • James Varghese added an answer in Hyperspectral Image Analysis:
    How to find Landsat equivalent bands in AVIRIS hyperspectral data?

    I have some AVIRIS hyperspectral imagery which covers a small area. I would like to scale this up using Landsat to cover a larger region. Is there a way I can find the Landsat equivalent bands in my data. For instance, the NIR peak in vegetation occurs in band 5 of Landsat 8 OLI imagery. How can I link this with my AVIRIS data? I essentially want to reduce my AVIRIS data (currently over 430 bands) down to the 7 most important bands that match Landsat (C,B,G,R,NIR,SWIR,SWIR2).

    James Varghese

    I agree with Richard, 'Spectral Resampling' in ENVI is one of the ways to do it. I have tried with hyperspectral laboratory measured reflectance values from 1.2µm to 16 µm and resampled it to e.g., ASTER TIR bands using Spectral Resampling tool and it works just fine. In fact with ENVI version 5.2 you will find pre defined L8 OLI filter function.

  • Louis Brassard added an answer in Gravitational Waves:
    What are the philosophical questions raised by gravitational waves?

    'On February 11, 2016, the Advanced LIGO team announced that they had directly detected gravitational waves from a pair of black holes merging' (Wikipedia)

    This is to invite views what sort of philosophical questions might be implied by this discovery?

    Louis Brassard


    ''If confirmed by other groups, the discovery would count as the strongest evidence yet for cosmic inflation''

    I do not understand why?  

    My first reaction of the recent announced was not philosophical but one of Awe.  It is one think to conceive that gravitational wave most probably existed according to well established theories and another things to detect them, to touch them.  The same reaction of Awe I had when on  Aug. 23, 1966, when we were shown for the first time a view of Earth taken by a spacecraft from the vicinity of the Moon.  We knew since Copernicus vision that such a view was possible.  I had seen in my Tintin Book but to really see it is different.  And here we are at that moment with gravitational wave that Einstein imagined as soon as gravitation was conceived as a curvature of spacetime.

    Such as abstract notion.  A few years before that the same Einstein advocated giving up this idea of an ether sustaining the propagation of light in space.  And now an emptiness combined with time was imagined to have a curve.   Very strange type of emptiness and time indeed. Which reminded us of the critic by Leibniz of Newtonian time and space.  Leibniz advocated that intead of conceiving time and space as the containers of events and locations to conceive them as relations between events and locations.  General relativity has in many ways provides us with a dynamic relational  conception of time and space and now we are not only contemplating these conceptions but actually touching them with LIGO.  We see in real time space contracting and use this information as Galileo taking his telescope and pointing it to the sky. At that moment, Copernicus theory ceased to be only a conception but became more real; what had been only touching with the mind had became touching with the eye.

  • Munazzam Ali Mahar added an answer in Rutile:
    How do I deplete Nb and Ta from rutile?

    Nb and Ta are more than 2000 ppm in rutile. Is there any literature regarding depletion of these elements or example where this is done on industrial scale? Also how might I deplete REE from pyroclore?

    Munazzam Ali Mahar

    Thanks Ariadne

  • Sebastian Schuch asked a question in Pleurotus:
    Are the hyphae of epigeous basidiocarps able to disintegrate dead insects?

    I discovered the remains of a midge on the fruiting body of Pleurotus eryngii. The hyphae obviously overgrew the (disintegrated?) corpse, but parts of the exoskeleton are still visible.

  • Marcelo Guimarães Silva asked a question in Postural control:
    Which data can I explore through the center of mass (CoM) displacements?

    The study of CoM is very important, mainly to investigate the coordination between posture and movement. It's an interesting device which can help us to identify, for exemple, the postural control, the postural adjustments, or the overall subject's behavior through analysis of body segments. However, how can we interpret the CoM data results? In this specific case, amplitude and speed in A/P or M/L directions.

  • Agostino Prástaro added an answer in Cosmology:
    Is there Godel's Incompleteness Theorem in Physics like in Mathematics?

    The holy grail of Physics is the Unification Theory called by Weinberg as the "Final Theory". When finally discovered, perhaps it can:

    1. Unify all fundamental forces in nature.

    2. Explain the Hierarchy Problem

    3. Explain all Cosmological Problems 

    5. Gives us the right Quantum Interpretation

    but can such theory derive all fundamental dimensionless constants in nature out of pure number and explain the true nature of time?  

    Agostino Prástaro

    Right Charles !

  • Aslanbek Naziev added an answer in Hilbert Space:
    How is Inner product space related to Euclidean and Hilbert space? How and why is the concept of inner product spaces developed?

    In high school I just studied the concept of vectors and the dot products. Now, I see more advanced concepts of these, like, norms induced by vector spaces. I want to see why and how these concepts are developed and why they are used.

    Aslanbek Naziev

    There was also the second part of the question,

    "How and why is the concept of inner product spaces developed?"

    As a possible answer to this question the very beginning of the §10 of Loomis' book "An introduction to abstract harmonic analysis" may be quoted:

    "A Hilbert space H is a Banach space in which the norm satisfies an extra requirement which permits the introduction of the notion of perpendicularity. Perhaps the neatest formulation of this extra property is the parallelogram law:

    llx+y||^2 + llx-y||^2 = 2[||x||^2 + ||y||^2]."

    This permits also the introduction of inner product as is well known (and shown in the cited book and, of course, many other books).

  • Andres Munera asked a question in Self-Regulated Learning:
    Does anyone have anything about self-regulated learning assesment?

     Hello, my name is Andres Munera and I´m a psychology student from the Fundación Universitaria Konrad Lorenz from Bogota, Colombia, doing my internship. I´m doing the validation by convergence  of an instrument about student´s autonomy and i need and instrument that evaluates self-regulated learning. Can anyone please help me, by providing some literature and a instrument, thanks.

  • Bekk Okk added an answer in WPF:
    How can use EMGU library in WPF programming for 3D laser scanner?

    I want to try use emgu library(Open CV) in .net .

    but i cannot run it and get Image from camera.

    Bekk Okk


    j'ai trouvé ce code C# dont je n'est rien compris, mais qui peut etre une aide pour toi:

    le lien du site est:


    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Diagnostics;
    using System.Drawing;
    using System.Text;
    using System.Windows.Forms;
    using Emgu.CV;
    using Emgu.CV.Structure;
    using Emgu.Util;

    namespace CameraCapture
    public partial class CameraCapture : Form
    Image<Bgr, Byte> image;
    private Capture _capture;
    private bool _captureInProgress;

    public CameraCapture()

    private void ProcessFrame(object sender, EventArgs arg)
    image = _capture.QueryFrame();


    captureImageBox.Image = image;

    public void Run()

    Image<Gray, Byte> gray = image.Convert<Gray, Byte>(); //Convert it to Grayscale

    //normalizes brightness and increases contrast of the image

    //Read the HaarCascade objects
    HaarCascade face = new HaarCascade("haarcascade_frontalface_alt_tree.xml");
    //HaarCascade eye = new HaarCascade("haarcascade_eye.xml");

    //Detect the faces from the gray scale image and store the locations as rectangle
    //The first dimensional is the channel
    //The second dimension is the index of the rectangle in the specific channel
    MCvAvgComp[][] facesDetected = gray.DetectHaarCascade(
    new Size(20, 20));

    foreach (MCvAvgComp f in facesDetected[0])
    //draw the face detected in the 0th (gray) channel with blue color
    image.Draw(f.rect, new Bgr(Color.Blue), 2);


    private void captureButtonClick(object sender, EventArgs e)
    #region if capture is not created, create it now
    if (_capture == null)
    _capture = new Capture();
    catch (NullReferenceException excpt)

    if (_capture != null)
    if (_captureInProgress)
    { //stop the capture
    captureButton.Text = "Start Capture";
    Application.Idle -= ProcessFrame;
    //start the capture
    captureButton.Text = "Stop";
    Application.Idle += ProcessFrame;

    _captureInProgress = !_captureInProgress;

    private void ReleaseData()
    if (_capture != null)