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

  • Marcileida Dos Santos added an answer in Google Analytics:
    Is anyone working with social media data?

    or using google analytics or other tools? any recommendation please?

    I am working with social media data, one of the chapter of my PhD. Facebook, Twitter,Instagram, Google +,Thumbl etc. I want to know the best way to gather my data. Thank you 

    Marcileida Dos Santos

    Fabulous! Thank you so much:)

  • Marcel Ruiz-Mejias added an answer in LFP:
    May I use tetrodes to record LFP and single-unit activity at the same time?

    I will implant 8-tetrode flexDrive and record single-unit activity in freely-moving rats. And I also want to record LFP. I am wondering whether it is possible to get good LFP signal from tetrodes with the same recording parameters of spike recording. I noticed in some papers, with tetrodes, the signals are splited and received by two amplifiers.  In one paper, for spike recordings, they use amplified 5000×, and bandpass filtered between 600 and 6000 Hz . For LTP, the signals are amplified 1000×, continuously sampled at 1874 Hz, and bandpass filtered between 1 and 475 Hz. I am wondering whether I could use one amplifier, amplifier 5000 ×,bandpass flitered between 0.1 and 8000 Hz, 32 kHz sampling rates for both LTP and single-unit activity recording.


    Marcel Ruiz-Mejias

    I would say is better to use the right amplification for your LFP, given that you are interested in oscillatory activity. Then you have to check which is the correct amplification you need to see the real amplitude of your LFP signal in your screen. I mean there's a unique amplification that gives the real signal, and this you have to find. Normally, for oscillations, if you have your units in you recording software expressed in uV (microV), then you have to amplify 1000X.

    Also, 1000X is a good amplification for see nice spikes.

    Another thing is that you will need to split the signals in LFP (0.1-500hz) and Single unit (600-6000hz) signals by filtering.

  • Ali A R Aldallal added an answer in Urinalysis:
    Does anyone know about retrospective study on the use of Urinalysis and urine dipstick in diagnosing UTI?

    Does anyone knows about retrospective study on the use of Urinalysis and urine dipstick in diagnosing UTI?

    Ali A R Aldallal

    Kindly check out the articles attached below.

    Best Regards

  • Wouter van der Westhuizen added an answer in Gram Staining:
    In Gram staining, what are the tiny dark purple dots inside the bacterial cells?

    Can anyone please view the attached picture and tell me what are tiny dots inside bacterial cells that have been stained dark purple as opposed to lighter purple cells? Cells are one day old on LB plate.

    Thank you in advance.

    Wouter van der Westhuizen

    Those don't look like spores,; looks like structures on the outside of the cells. Are you growing the bacteria in any detergents or any other environmental stress factors?

  • John Chng added an answer in Advertising:
    Attitude towards controversial advertising(weight loss program).

    Can anyone share their recent findings on attitude towards controversial advertising(weight loss program)?

    John Chng

    Dear Phil,

    Thank you for your prompt reply.Actually, sexual imagery verging on the explicit in advertising is controversial.Please do response and share on your research area.

    warmest Regards

    John Chng

  • Benjamin Gillich added an answer in Survey Research:
    Can you help with my survey on wildlife?

    Please help me with my University degree survey. It will only take a few minutes to fill this in. Everything is anonymous. Thank you!

  • M. Chaitanya Varma added an answer in Gaussian:
    How can I find the value of translation vectors, labeled by Tv for calculating band structure of a crystal using Gaussian?

    Atomic positions in a crystal can be given from .cif file, but to consider PBC we have to give translation vectorsTv.  in each direction how to know a specific value that to be given?

    M. Chaitanya Varma

    thank you sir

  • Ahmed Hashem Abdelmohsen added an answer in XPS Analysis:
    How can I do XPS analysis for metal oxide powder?

    Sample preparation for analysis?

    how to avoid contamination of chamber? 

    Ahmed Hashem Abdelmohsen

    Did pressing pellet at room temperature efficient for XPS measurements?  Should i use some binder as you mentioned before ( Is there different types of binder that i can use?)

  • Grzegorz Dudek added an answer in Sensors:
    How do i calculate optimal placemen using GA?

    Dear ALL

    iam working on optimal placement of sensors on plate using genetic algorithm

    The plate is divided into 100 elements encoded by sequential integer numbers
    01, 02,...,100; each representing a possible location of a sensor as shown in
    Figure 1
    chromosome length contains seven genes for sensor as shown in Figure 2
    locations and the chromosome is marked with its fitness value as shown in Figure 2

    i need to design a matlab code crossover procedure to avoid repeated sensors in the child

    any one can help please

    Grzegorz Dudek

    Some idea:

    A=[1 2 3 4 5 6 7];
    B=[5 6 7 8 9 10 11];
    C = union(A,B);

  • Wouter van der Westhuizen added an answer in Membrane Protein Purification:
    What can I do to prevent my protein from precipitating on a Nickle IMAC column during denaturing conditions?


    I'm trying to purify an over-expressed membrane protein which I suspect is stuck in inclusion bodies. I extract the proteins using 8M Urea in a 50mM Tris-HCl (pH 7) buffer containing 20mM imidazole and 0.5M NaCl. I ultracentrifuge the sample before loading it onto the IMAC column. During loading, the column gets clogged quite soon. When I try to elute the protein at very low flow rates on FPLC (to prevent over pressure), the proteins come off very slowly (during most of the linear gradient from 20mM to 500mM Imidazole), especially my protein of interest. 

    What should I try to prevent the protein from precipitating/clogging onto the column?

    Can something like a phosphate buffer possibly have a different effect vs a Tris buffer? Should I try a higher/lower pH? Less NaCl?

    PS: pI of my protein is 8.5, truncated version of the protein (just the hydrophilic part) purifies perfectly as it's completely soluble. 

    Wouter van der Westhuizen

    Thanks, I've managed to get hold of some sodium deoxycholate, will try to purify again on Friday if everything goes according to plan and will report back. I really hope it's just a lipid problem and not something else!

  • Jirka Holler asked a question in Oxygen:
    How is it with oxygen concentration?

    If somewhere is such a statement "In the body, oxygen concentrations
    range from 1 to 12%", what is the oxygen concentration in mg/ml? How can one calculate this value? 

  • Ronald Staples added an answer in Narrative Inquiry:
    Narrative inquiry: can anyone direct me to an example of a narrative interview guide?

    I have developed a narrative interview guide drawing on Clandinin et al's  (2007) three commonplaces but it would be useful to see other examples.  Plus in narrative inquiry does anyone have a link to literature about giving the interview schedule to the participant prior to interview?  I thought I would but have no evidence to support this. helen

    Ronald Staples

    I totally agree with Theodore, if you want to provoke a narration, it is necessary to be very well prepared concerning your issues of interest, but a schedule in any sense wouldn't be helpful. Therefore i suggest, tell your interviewpartner about the topics you are interested in but do not provide something like a schedule or a structure of interview parts. Your partner will think about this and will anticipate that you will ask him in a certain way. I strongly recommend the works of Fritz Schutze, who has worked intensively on narrative interviews as method in the field of biographical research. Maybe this will be a good starting point: 

    Schutze, F. (2008). Biography analysis on the empirical base of autobiographical narratives: How to analyse autobiographical narrative interviews -part one. European Studies on Inequalities and Social Cohesion, (1-2), 153-242. Retrieved from http://search.proquest.com/docview/60322027?accountid=10755

    Finally it would be helpful for any kind of recommendation on methodical issues to know what your research question is. Why do you suppose narrative interviews are the appropriate method for your interests?

  • Gintaras Tamosauskas added an answer in Quantum Optics:
    How can I increase the frequency of photon pair generation via spontaneous parametric down conversion (SPDC) to an ultra-fast magnitude?

    Solid-state lasers used to pump SPDC crystals can produce light pulses at rates only up to a few hundreds of MHz. Can someone suggest to me a scheme of say doubling the rate of photon generation using the same laser pumps. I will also appreciate any link to publications that can give me a better insight.

    Gintaras Tamosauskas


    first of all is laser CW or pulsed?

    If CW you can increase length of the nonlinear crystal (obvious). Or use crystal with higher nonlinearity. But choice of  crystals is limited because typically it is dependent on application and nobody wants to use some "other" crystal which do not fulfill other parameters. However with CW laser maybe exotic one can be used without afraid of being burned.

    SPDC is in general scattering process which depends on number of pump photons and nonlinearity (scattering probability) of the crystal. So, you need increase number of pump photons. SPDC will increase linearly. However this is valid only for fixed spatial and frequency bandwidth. Easiest way to increase number of SPDC photons is to increase bandwidth. Say you are using 10nm interference filter for monochromatization. Number of pairs will increase twice if filter will be of 20nm bandwidth. One can say this is not very correct, but comparing with bandwidth of CW wave anyway it is infinity times not bandwidth limited. So, what the difference if it will be 2 times infinite? For the experiment, if correctly designed, there will be no difference either. Anyway there is no way to narrow down to single longitudinal mode.

    Typically people are using fibers as criers of the photons. Proper matching of numerical apertures of imaging optics - source diameter and NA of the fiber is critical for best collection of generated ones. If spatial bandwidth is limited too much there are losses till experiment itself will take place. This is only "technical" drawback but you can loose lot of you signal without knowing that it can be much larger.

    With pulsed laser intensity can be increased by focusing and stimulated process will start as result. This will increase average number of photons per pump pulse. But not frequency which depends on rep rate of the laser. Number of pulses can be increased by mounting Michelson interferometer with one arm delay equal to half of rep rate (other close to 0). Simple way to double pulses with 50% energy loss. One more interferometer and you will have 4 times frequency with 75% energy loss (in best case).

  • Marcel Rossewij added an answer in Piezoelectric Materials:
    How do I make a power supply of high voltage (100 V), high frequency (8-10 MHz) and current of mA?

    Hi all,
    I need to test my MEMS device, which is designed with piezoelectric material. The problem I am facing is, in providing the power supply i.e., a High voltage (around 100 V) while the frequency is RF one (about 8-10 MHz), current can be mili Amps. I do have a signal generator which is having variable frequency range upto 15 MHz but difficulty is in voltage as it has only 10 Vp-p. How can I able to reach my device requirements?

    Marcel Rossewij

    Maybe Apex has a suitable amplifier, e.g.:


  • Laurence Stuart Hall added an answer in cDNA Synthesis:
    Is there a protocol for performing Reverse Transcription and cDNA synthesis on extracted RNAs, from common lab reagents, not the expensive kits?

    Is there a protocol for performing Reverse Transcription and cDNA synthesis on extracted RNAs, made mostly from common lab reagents, not the expensive kits?

    Laurence Stuart Hall

    Hello Andrew

    You will require:

    1. A reverse transcriptase

    2. Buffer

    3. MgCl(2)

    4. dNTPs

    5. An RNAse inhibitor like RNASin

    6. OligodT(15-20) or random hexamers

    Self assembly from ready to hand common lab reagents was more common back in the early 90s when I first started performing RT:

    Promega was at the forefront back then, e.g.



    See also the attached pdf

    If you go onto academic web sites it might even be possible to adduce generic buffer composition 

    Hope this helps !! 

  • Robert Zdechlik added an answer in Hydrogeology:
    What is the resolution (dpi) required for coloured graphs and maps - Hydrogeology Journal?

    I am preparing the paper to be published in the Hydrogeology Journal and I do not understand the instructions that specify the resolution for the figures. They specify:

    • 300 dpi for "halftone art" (including drawings)
    • 600 dpi for "combination art"
    • 1200 dpi for "line art", (black and white graphics with no shading).

    One of my figures is a map, in colour. The other four figures are graphs consisting of coloured lines and some have circular symbols. Do all the figures represent "halftone art" or fall in other categories?

    Thanks for helping!


    Robert Zdechlik

    Colour map is a kind of  "halftone art"

    Colour graph is a kind of "combination art"

  • Badis Haddag added an answer in Sheet Metal Forming:
    How can we analyse minimum quantity lubrication in deform2D software?

    in dry machining we set friction factor easily but in mql how we assign friction factor ...

    Badis Haddag

    in addition you can introduce adequat heat transfer coeffients

  • Sandeep Karki added an answer in RID:
    How to get rid of virus named ransomeware having extension ccc at the end??

    Yesterday, my laptop got a deadly trojan virus having extension ccc that affects  each of my files. Afterwards, all my files were encrypted to the bizarre format that couldn't be opened by any installed program. Even tried to look up for for software to decrypt my affected files but didn't find any. It seems to a serious issue, I would be really grateful if I could know any ways to resolve this problem. Thank you.

    Sandeep Karki

    Unfortunately, the virus got into my laptop through the link attached with the junk mail that I opened accidentally. From there, all my files turned into a format having extension ccc at the end and they were asking for money to get it repaired. As i searched, I got to know the virus to be ransomware and somewhere, it has been named as cryptolocker virus. But, couldn't figure out any app or program that potentially can open the file. Got into a big trouble and taking this platform to get some advice to sort it out. Hope something could be done so I could restore everything back.

  • Santhosh Kumar M asked a question in Sputtering:
    Is that possible that we can make our own customised target for sputtering?

    Presently I am using some basic targets which avail in markets. I just want to coat my synthesized material via sputtering. Is that possible that we can make our own target. I like to try the possibility please suggest me if any.

  • Abdul Owais Mohammad asked a question in IDEA:
    Can i get the idea about how to simulate security issues on VoIP?

    please help for this idea

  • Renato Lopes asked a question in Cast Iron:
    Is there any correlation between flexural stregth and yield strenth for cast iron?

     Any proven mathematical or mechanical correlation is welcome.

  • Safia Janjua asked a question in Phylogenetics:
    Anyone working in lab with ungulates experts?

    I am in search of supervisor who can help in the phylogenetic and bioinfomatic analysis of sequence data of some ungulate species.

  • Dahmani Affaf added an answer in Rhizobacteria:
    What is the best application of plant growth promoting rhizobacteria ?

    what is the best method to evaluate the plant growth promoting potential for my strain on arabidopsis thaliana ; inoculation of seed or soil? and in vitro or vivo?

    Dahmani Affaf

    thank you all for your answers

  • Julia Frohne added an answer in Celebrity:
    What influence do you feel that celebrities have on their followers through social media networks?

    Celebrities-both those who are famous offline and those who are famous because of their online presence, micro-celebrities have 80,000 followers online according to Marwick & boyd (To See and Be Seen: Celebrity Practice on Twitter, 2011, pp. 139-158). 

    Julia Frohne

    In Germany, we have a few celebrities on Youtube who are very influencial especially on the younger generation. Very interesting is, that some of them do not intend to influence follower´s meaning about products, their goal is to support the political education. Here we have a role model for the tradional media, which often do not reach those audiences with their messages.
    Look on youtube e.g. for  "LeFLoid", he has 2.7 million subscribers ... And he had already interviewed our chancellor Angela Merkel.


  • Isabel Garcia added an answer in Conservation and Restoration of Cultural Heritage:
    Does anyone have any bibliography on the outcomes or long term results of heritage reconstruction projects?

    I'm interested in evaluating how the original criteria that substantiates a heritage reconstruction project (after a natural disaster or warfare) turn out in reality.
    I would like to identify, among other things, if these projects actually contribute to social healing/rehabilitation or to the development of the area, and if they are successfully linked to the community. And if not, to identify what unforeseen factors were involved in the project that prevented the initial objectives from being met.

    Isabel Garcia

    Sorry I don´t know what happen to the link 


  • Renjith Bhaskaran added an answer in Theoretical Chemistry:
    How do I use QST2 in Gaussian to find Transition State?

    I'm trying to re-create the results from (Theoretical Chemistry Accounts 125(3): 269-278) where the authors determined the transition state and activation energies for DNA-nucleobase alkylation by sulfur mustard/ mustard gas.

    When I try and run these calculations, I get a termination error (/export/software/GaussianNew//g09/l101.exe). I was wondering if anyone could offer insight or try and recreate the results from this paper and maybe give a walk through of how this is done. Admittedly, I am not a computational chemist - I try and stick to synthesis but am working on an independent proposal for my PhD program and wanted to learn more about this field.

    Thanks in advance for your help!


    Eric Z

    Renjith Bhaskaran

    Dear Eric,

    for your query on " the activation barrier is about 10 kcal/mol off from the result obtained using the Gaussian 98 package. Between packages, is it normal for energies to differ by this value?"

    An energy difference of ~0.5 eV between packages seems to be unusual. My suggestion is to verify the TS geometry and the imaginary frequency that you got with the published data, if available. If you find this is within the error limit, then you should further confirm it by performing an IRC calculation. If IRC ended in the reactant and product direction, then (in this case) you can confirm TS is actually a first order saddle point.

    regards, renjith

  • George Ojwang added an answer in Financial Markets:
    Where can I get good papers on investor behaviour towards IPOs (initial public offerings)?

    One of my students is taking up her research project on studying investor behaviour towards IPOs (initial public offerings) in Nepal. I've come across a mention regarding a paper in the Journal of Finance but could not retrieve it for her any way. Please get me some good papers.

    George Ojwang

    Hi Arhan,

    These two documents attached will help her build her case.



    + 1 more attachment

  • Augustine Ifelebuegu added an answer in Sludge Treatment:
    Who one is working on treating solid form of sludge by using bacteria?

    I have some doubt regarding this field. kindly drop your address with email who is working in same field. i will contact them.

    Augustine Ifelebuegu

    I have designed and operated anaerobic sludge digesters. contact aa5876@coventry.ac.uk if you need further details.

  • Elisa Alvarez Llopis added an answer in Crusades:
    Hi. I am looking for primary and secondary material on 12th and 13th century Navarre? Can anyone point me in the right direction?

    At the moment I am looking at the role of Iberian mercenaries in the twelfth and thirteenth century. I am principally looking for reasons for their prevalence in southern France during the period of the Albigensian crusades, but I am also looking for some background info on the Basque region and the kingdom of Navarre during the period. The primary sources I have are all Anglo-Norman and French in origin.

    Elisa Alvarez Llopis

    Creó que debería consultar la Colección de fuentes medievales del País Vasco ,editadas por el. Gobierno vasco, en ellas encontrará documentos del Archivo General de Navarra, sección de Cómputos, Carlos Ii ..

    También le puede resultar productivo la consulta de Irargi, Centro documental del País Vasco, donde puede consultar on-line toda la documentación 

    Esperó que le resulte productivo