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  • Jamail Lu added an answer in Cytotoxicity Assays:
    What is the difference between an antiproliferative assay and a cytotoxicity assay?
    When we want to screen or test the effect of a natural product in cancer cells, we have to know how safe is it. Why do some articles mention antiproliferative and others cytotoxicity assays for this screening or testing?
    Jamail Lu

    Yes, these two assays are very confusing whether we have to do antiproliferative assays again after cytotoxicity MTT assay. Some said NO because the same meaning and other said here it make sense to do further study for anti-proliferative assays. 

    So, here I would like to raise one question. If I decided to do anti-proliferative assay after MTT test, whether do I need to treat the cells with different concentration as in MTT or just with the IC50 concentration of compound but check different time point 24, 48, 72 hr if there are proliferations. If I am not wrong, using IC50 concentration only to study proliferation makes more sense. Any opinions for this point? 

    If we do RTCA after MTT assay, do anyone suggests to do antiproliferative assay too or not necessary?

  • Syed Abbas Jafar added an answer in Coral Reef Ecology:
    Is it Favia maritima?

    Photograph taken during underwater survey in West Coast of India. At 20m depth.

    Syed Abbas Jafar


    There are several names used for Favia including Brain coral in aquarium trade, but its also known as perhaps "Knob coral". I agree that scientifically, calices with typical meandroid feature should be named as "brain Coral". Moreover, Favia (synonym of Dipsastraea) is reported from Indo West Pacific -what do we understand by "There is no Favia in the Indo-Pacific anymore" ? Please have a look at the link.




  • Rajan Parajuli asked a question in EViews:
    How can I estimate time-varying speed of adjustment parameters in error correction equations?

    I would like to estimate time-varying speed of adjustment coefficients in a bi-variate VEC model using a state-space and kalman filter approach. Could you please help me in setting up the program code in EVIEWS or R or STATA or even in SAS? Your help would be highly appreciated. Thank you.

  • Soumitra Hazra added an answer in Dielectric Constant:
    What is the refractive index of SrRuO3 in the terahertz frequency range?

    The refractive index of SrRuO3 in the optical frequency range is known. But in the terahertz frequency range the refractive index even the dielectric constant of the SrRuO3 is unknown.

    Soumitra Hazra

     Hi Milad,

     Thanks for your reply. I am also started work on SrRuO3 thin film. I don't have any information regarding the refractive index or dielectric spectra of SrRuO3 in the terahertz frequency range. I just want to know  that thing.

    Best Regards

  • Montserrat Hernández-López asked a question in Unemployment:
    What do you think about a genetic algorithm to forecast chain of personal characteristics of unemployment population using a transition matrix?

    I have designed a genetic algorithm to predict the chain of personal characteristics of the unemployed population replacing crossover and mutation operators with a transaction matrix containing the probabilities of transformation of a string in another. I'd like to know your opinión.

  • Jamie Bartlam added an answer in Basic Statistics:
    How good is my data should I test for normality?

    Firstly I'm definitely no statistician so be gentle with me.

    I Have 17 data sets from likert scale questions with possible answers of 1,2,3 and 4. I have this for 70 different questions from the 17 participants

    I would like to assess how good my data is. I think the best thing to do would be to assess normality

    I have tried a calculation i found in excel and using spss and the Shapiro-Wilk test

    The excel normaility test suggests a lot of my data sets (ie data from each question) have some degree of normality but the Shapiro-Wilk not so much.

    The problem is when looking at the histograms and normal Q -Q plots they look fairly normally distributed to me. for example the following data set


    question is should I bother at all and if so am i doing it right?

    Jamie Bartlam

    Not sure if your all still following this but on the off chance.

    Thanks so much for the help.

    I get that the data is ordinal so normality not relevant to statistically evaluate my data. from your jumping off point I've been using cronbachs alpha which returns high values mostly over 0.9.

    Am I right in say this means my data is homogenous and unidimensional and therefore at least relaible if not valid.

    Could just do with knowing if I'm back on track or not?

    Thanks again


  • Girish Mallapragada added an answer in Theory of Planned Behavior:
    Can a dichotomous variable (yes/no) be used in a multiple regression analysis of the theory of planned behavior?

    Hey guys,

    I have measured a number of components of the TPB using internally consistent 7-point Likert scale items. However, one component was measured using dichotomous items that simply ask questions like "Do people criticise you for doing this behaviour? Yes/No" -

    Can these kinds of questions be used in a multiple regression to test the predictive power of the different constructs of the TPB? If so, how? Any references on how to do this would be much appreciated.

    best wishes,


    Girish Mallapragada

    Yes, you can.  What you would then observe is the difference between the two groups in the mean the dependent variable.

  • Eleonora Stefanutti added an answer in Dynamic Light Scattering:
    Why can't I obtain an appropriate particle size for graphene quantum dot by DLS?

    I synthesised it with pyrolysis of acid citric and then added NaOH in it. I filtered it by PTFE syringe filter after centrifuge at 5000 rpm for 30 min, and tested it for some concentration.

    Eleonora Stefanutti


    I'm not sure to really understand what you mean...You prepared your graphene quantum dot, you measured it by DLS but the size you obtained is not the same you expected? What do you mean as "appropriate" particle size?

  • Mathilde Poujol de Molliens added an answer in RNA:
    Somebody have experience with HEK293A transfection, work with low serum is it important or not?

    I try to transfect HEK293A with lipofectamine 2000 and PEI. I used 1.5µg of DNA. When i used 10%FBS i have RNA expression but not protein expression and when i used media with 2.5%FBS i have not RNA expression.

    Thanks in advance

    Mathilde Poujol de Molliens

    Thank you.

    Before i make my transfection, i change cell media with DMEM 10%FBS or  DMEM 2,5%FBS. I prepare solution with only DMEM : one tube for lipofectamine (i wait 5 min) and one tube for DNA. I add lipo on DNA and i wait 30min, after i add 200µL on my cells (on 6 well plate). After 6-8h i change media again.

    For check RNA expression, i purify RNA with RNeasy micro kit from Qiagen, after i make classical RT-PCR.

  • Vladimir S. Myasnichenko added an answer in Gold Nanoparticles:
    Can anyone recommend a software or script to create structure (.pdb or .gro or .xyz) files of surface-coated gold nanoparticles?

    I would like to do MD simulation of surface coated gold nano particles. I require structure file of surface coated gold nano particle. Can somebody suggest me any software or script to generate these structure. 

  • Roman Tuma added an answer in Computational Structural Biology:
    Is there a CRYST1 (from pdb) that can be used to generate a full icosahedron from a monomer (ie add the other 59 subunits)?

    I know i can load, for example, pdb-1NQU into pymol and generate symmetry mates to produce a icosahedral capsid from a pentamer subunit (including other crystal contacts).  Does anyone know how i can do the same if i start with a monomer of that pentamer?  Can i recreate a icosahedral capsid from a monomer with pymol symmetry mates.


    Roman Tuma

    VIPER server mighty do that

  • Deborah Suchecki asked a question in Oxytocin:
    Can anyone recommend a reliable ELISA kit for rat neuropetide Y, oxytocin and vasopressin?

    Assay in brain and plasma samples

  • Rinat Nugayev added an answer in Universe:
    Why is there something instead of nothing ?

     LET US START BY WHAT  Robert Adler  WROTE   ON 6 NOVEMBER 2014--:
    People have wrestled with the mystery of why the universe exists for thousands of years. Pretty much every ancient culture came up with its own creation story - most of them leaving the matter in the hands of the gods - and philosophers have written reams on the subject. But science has had little to say about this ultimate question.

    Rinat Nugayev

    Life on our dear planet may be a fluctuation from nothing-1 to nothing-2

  • Girish Mallapragada added an answer in Innovation Network:
    How can I prove that innovation network exist and evaluate it?

    If I want to prove that innovation network is exist in Shenzhen High-tech Industry, how can I prove that? Is it possible to prove that without questionnaire survey? And how can I evaluate the strength of the network? Looking forward to your answer.

    Girish Mallapragada

    You could consider coding alliances and joint ventures between firms in the industry.  Other alternatives could be observing common patents across firms, co-ownership etc.  Strength could be frequency of interactions, number of alliances, number of shared relationships etc.  

  • Hala Hazzaa added an answer in Socket Preservation:
    Does anyone have any input on the effectiveness of L-PRF over PRF, and what are the benefits when applied to extraction sockets?

    Does it aid the speed of recovery? Long-term vs short-term benefits?

    Is it as effective in extraction socket as using of particulate graft material in socket preservation?

    Hala Hazzaa

    Dear Miriam, various protocols are available on the methods of using autogenous patient's regenerative products. Among these products, there are P-PRP, L- PRP, P-PRF, and L-PRF. L refers to leukocyte while P refers to pure. The L-PRF is one of the most preferred regenerative products in treatment of periodontal defects, dental implants, and extraction sockets due to its rich contents of leukocytes, PDGF, VEGF,TGF-b in addition to the essential molecules e.g. fibronectin, vitronectin, fibronigen,.. These products are tried and proved clinical efficacy (not only in healing events but also in pain control) when compared to P-PRF in treatment of extraction sockets.

  • Giovanna Artioli added an answer in Continuing Education:
    What do you use to evaluate the impact of continuing education in medicine?

    who recently published research papers on the evaluation of the training

    Giovanna Artioli

    Thank you very much for your contributions!!


  • Patricio Herrera added an answer in Design Research:
    Which research framework should I use and which sampling technique should I mention?

    It is hard to select research design approach being followed in my study. Since I did not randomly select(draw) sample from a population but I randomly assigned the 100 students equally to the control and treatment groups. Is it still random sampling? As random sampling means the selection of sample from population. I did this the other way around. Since it was convenience for me to work with a certain teacher so I took her classes for further experimentation. As far as, random sampling or selection is concerned, I can not use Quasi Exp design instead I can employ Experimental Design. Since the research was conducted in natural setting(school) and the independent variables(various instruction types ; conventional and an edu app instructions) were isolated, controlled and then manipulated which are against the Experimental Design and supports only the Quasi Exp Design. So what sampling technique should I mention in methodology section? Since I have employed Quasi Exp research Framework where I did Random assignment and I worked with experimental and control group. This is a bit confusing. 

    Campbell, D.T., Stanley, J.C. (1966). Experimental and Quasi-Experimental Designs for Research. Skokie, Il: Rand McNally.

    Cohen and Manion's Book

    "Random Selection & Assignment", retrieved from

    Patricio Herrera

    I understand as "quasi experimental" instances when a given intervention -mostly those you cannot use experimentally- affects a certain group of persons accidentally or unintentionally (regarding the resulting effects). That would be the classic Loperamide case. In such a situation, "randomization" does not exist, although a very small probability that both unintentional and randomization could occur. Besides, randomization is usually made following random numbers generated by a software program. I do not know how you made it. Nevertheless, any answer could fall wrong without knowing what you want to prove (or expect as result of your eventual analysis).

  • Teresa Njeri Kinyari added an answer in Mouse Models:
    Which strain of mice to investigate the toxicity of any drug? It could be BALB/c?
    Studies with substances to evaluate the toxicity in experimental animals.
    Teresa Njeri Kinyari

    Does it matter which strain of mice one uses if it is a crude extract of a natural product?

  • Arun Rathod asked a question in Parasitic Nematodes:
    Is there polyembryony specie of root knot nematode or any other plant parasitic nematode sp.?

    Is there polyembryony specie of root knot nematode or any other plant parasitic nematode sp.?

  • Manoj Kuppusamy asked a question in Outliers:
    Which is the best method to removing outliers in a data set?

    In statistically analyzing a data set, suppose we have to found some of the outliers, if necessary to remove them which method is appropriate?

  • Selamawit Serka Moja added an answer in OLS:
    What are the basic differences between OLS and Maximum Likelihood method?

    Dear researchers,

    It is very urgent to know for me the basic difference between OLS and maximum likelihood method. 

    Selamawit Serka Moja

    The MLE is concerned about choosing the parameter which can maximize the likelihood or equivalently the log-likelihood function. And then fit the model based on the trial estimated parameter value and calculate the mean of the model. To find the iterative weighted and working dependence and based on this two and the design matrix we can estimate the best parameter value.

    The OLS will take the parameter value which minimize the error ( residuals) of the model. It will take into acount that the residual sum of square and derivate with respect to the parameter regression coefficient (beta) and set it to zero and then we will find the parameter value which minimize the error(residual sum of square).

  • Ron Reiserer added an answer in Speed Control:
    Is it possible for Electronic Speed Controller (ESC) to turn brushless motor clockwise and anti clockwise?

    I am about to use brushless motor for my hovercraft project which include Arduino, GSM Shield and Android apps for system control. Helps will be highly appreciated. Thank you.

    Ron Reiserer

    That ESC has a different wiring set up than a single motor ESC. The wires that are permanently attached are two thick wires (black and red) for the battery and six thin wires for the motor PWM (programming) inputs (four white wires), a ground (thin black), and a battery eliminator circuit output for the receiver +V (thin red). It also has four sockets to attach the motors (no wires). Documentation for this ESC is some of the worst I've seen. Luckily, it is probably running the SimonK firmware and you can find better programming instructions by searching for that firmware manual. In my brief overview of the device, I was not able to find information about running the motors bidirectionally. You will need to get more technical information about the firmware and possibly re-flash the controller with something that will allow motor reversing. You can try to do the throttle calibration and instead of putting the throttle (PWM signal) in the minimum position (PWM value 0), put it in the mid position (PWM value 127). This could make all values below 127 reverse values. This may to work with that firmware so you should verify it in the documentation. It should not hurt anything though.

  • Irene Zweimüller added an answer in Seabed:
    Can anyone comment on this map made by me presenting increased likelihood of methane in the southern Baltic?

    The map is  calculated on  the basis of  acoustic  observations of  the methane expulsions and  correlated type  of the  seabed - the  chart  of the  most probable  zones of  methane presence was calculated by me for  the  southern Baltic  Sea.  The methane  area is  well correlated with deeper stagnation areas.

    Irene Zweimüller

    Hi, Andrzej,

    Interesting work!

    If you want to stress the correlation between methane and depth you might want to include isobathic lines (not too many!) in your graph. 

    I´d also change the text of the legend, perhaps

    a) area surveyed

    b) area with high probability of methane occurrence

    and please use a less bight colour to mark the land - the green attracts too much attention

    best wishes


  • Anik Dutta asked a question in Restoration:
    Is it wise and scientific to perform only one cross between a CMS line and a restorer line to find the genes restoring fertiliy in the F1?

    Or do I need to perform several cross between CMS and restorer lines with different genotypes?

  • Vincent Lefebvre added an answer in Beetles:
    Can anybody determine this Cerambycid beetle?

    Determination only with pictures is difficult or impossible, I know.

    I thought, it is Acmaeops septentrionis, but I am not sure.

    Germany, Bayerischer Wald, 320 m, Meadow in a small river valley, 2009-05-17

    Thank you for your help!

    Rudolf Ritt

    + 1 more attachment

    Vincent Lefebvre

    Hi Anders,

    We would need a better view of the hind angles of the pronotum to be sure, but here shoulders seem distinctly wider than prothorax, which is not the case for P. pubescens because of its big and acute pronotal posterior angles. 

  • Gabriela Auge added an answer in Arabidopsis:
    Which kind of protocol to extract dna from Arabidopsis seeds contained in one silique ?


    I need to make some dna extraction from Arabidopsis seeds, and also from leaves. Ideally, the protocol should be the same for these two tissues. My idea is to try CTAB derived protocols.

    The problem is the following, that is why Im asking you. The extractions on Arabidopsis seeds will be done on seeds contained in only one silique. This represents approximately 300µg of material. The protocols that I have selected all use around 10mg of tissue. 

    Is it possible to extract dna from such a low amount of tissue ? How would you do it (first difficulty I see is how to grind the seeds without loosing too much material, for example) ?

    Thank you.

    Gabriela Auge

    Hi, I use quartz sand (cat. #274739, Sigma-Aldrich) when I'm handling small samples and it works very well as a grinding helper (even with dry seeds samples). I've also been using lately the Epicentre kit "MasterPure™ Complete DNA and RNA Purification Kit" because I needed to extract both DNA and RNA from a unique sample and proved to be quite efficient with the small ones.

    Hope this helps!

  • Alejandro Martin added an answer in Assay Validation:
    Why RNAi resistant cell lines cannot rescue the phenotype?

    hi everyone,

    I am recently performing RNAi rescue assay to validate the siRNA for gene/protein A specificity. I construct cell lines expressing wild type gene/protein A and RNAi resistant gene/protein A (that is, the mRNA sequence corresponding to siRNA were mutated to another condon, but coding the same amino acid, so that RNAi will not interefere the RNAi resistant gene/protein A expression). Unfortunately, cells expreesing resistant gene/protein A cannot rescue the phenotype caused by siRNA for gene/protein A. Noteworthy, RNAi resistant gene/protein A indeed cannot be interefered by siRNAs. And the phenotype we observed had been reported by another two groups previously. More important, different siRNAs sequence were used by us and the other two group. So, does anyone know the reason for such weird thing?

    Thanks in advance!


    Alejandro Martin

    Have you verified that the suposedly resistant gene is not being knocked down (using e.g. RT-qPCR)?

  • Niyazi Bilim added an answer in Mine Ventilation:
    What are the similarities and differences between the disciplines of mine ventilation and tunnel ventilation?

    In terms of physics of the problem like aerodynamics, heat transfer, and type of equipment used?

    Niyazi Bilim

    Galleries can be ventilate by taking advantage of pressure difference. But it is very hard used in tunnel (height difference). 

  • Fernando Lobo Pimentel added an answer in Data Envelopment Analysis:
    Software for DEA ( Data envelopment analysis) reqired?

    Dear fellows do anyone have some full software for DEA analysis, from internet i can only find limited edition or paid ones? i need to perform DEA for efficiency of 243 Banks for 15 years

    Fernando Lobo Pimentel

    I have successfully used the following free DEA computer program in my master thesis some years ago:


    Check the previous RG questions:
    1."Can anyone direct me to a good DEA software or add-in?"
    2.“Can anybody suggest a good package for running Data Envelopment Analysis?

    Can you recommend a data envelopment analysis softwares? - ResearchGate. Available from: https://www.researchgate.net/post/Can_you_recommend_a_data_envelopment_analysis_softwares/1 [accessed Nov 30, 2015].

  • Debra Sharon Ferdinand asked a question in Academic Writing:
    Does anyone have online academic writing exercises such as quizzes and the like?

    I need to provide some practice academic writing exercises for graduate students doing their final research papers. However, I thought I can save time by using what's available, so I am asking if you have such online resources that students can actually do online and receive automatic feedback (e.g., citing in APA, case study terms, etc.).

    Many thanks,