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  • Sahil Chaudhary added an answer in Applied Statistics:
    Why divide by n-1 when estimating standard deviation?
    In many probability-statistics textbooks and statistical contributions, the standard deviation of a random variable is proposed to be estimated by the square-root of the unbiased estimator of the variance, i.e. dividing the sum of square-deviations by n-1, being n the size of a random sample. Does anybody know why such an estimator is anchored in the statistical literature? Is there any technical reason supporting the use of this estimator?
    Sahil Chaudhary · University of Waterloo

    This video will answer your question in detail.

  • Henry Rosales-Méndez added an answer in Fuzzy Clustering:
    What is the best measure to validate Fuzzy Clustering Algorithms?

    I want to measure the quality of a fuzzy clustering algorithms, and I need a reliable measure to do this.

    Henry Rosales-Méndez · University of Oriente (Cuba)

    Thank you Said Jadid Abdulkadir, but, can you recomend me any external measure for fuzzy clustering validation?? Do you know about any gold standard (ground truth) for fuzzy clustering??

  • Abdelrhman Khattab asked a question in Isolation of Fungi:
    Is found Solid selecting media for citric acid production?

    I want to isolate microorganisms has ability to produce citric acid but I found difficult component solid media for yeast only, May I use it for bacterial and fungal isolates or not.   

  • Ali Akbar Shaikhzadeh added an answer in Shear Walls:
    when can I say that the behavior of shear wall and deep beam are similar to each other under seismic load?

    when can I say that the behavior of shear wall and deep beam are similar to each other under seismic load?

    Ali Akbar Shaikhzadeh · Ferdowsi University Of Mashhad

    I think they might act mostly the same under seismic loads.

  • Jean Ramon Dee Yap added an answer in eCL:
    Anti-actin (plant) works perfectly fine but phosphoantibody produces very high background. Any suggestions to reduce background?

    I've already tried every way possible (I think).

    I've increased the dilution of antibody, washed for longer and for more times, cleaned everything, diluted the ECL reagent, decreased exposure time, etc.

    I don't know what else to do to remove background from phosphoantibody. Any comments? Suggestions? Thank you!

    Jean Ramon Dee Yap · The Hong Kong University of Science and Technology

    Thank you so much for your suggestions! I will try to do each of them to see what fits best. Thanks!

  • Ivo Carneiro de Sousa added an answer in Language:
    ¿Por qué los hispanoparlantes que utilizamos research gate no hacemos preguntas y nos comunicamos en nuestra lengua materna?

    Los profesionales que hablamos castellano deberiamos comunicarnos y hacer preguntas también aquí en nuestra lengua y promover nuestro idioma que se habla en dos continentes. ¿Qué opinan?

    Ivo Carneiro de Sousa · City University of Macau

    I don't have any personal problem in using my mother language, Portuguese. The problem is if we all start using Spanish, Portuguese, German, Malay, Indonesian, Chinese, Japanese, French, Italian and tens and tens of other languages it will be rather difficult to follow up questions, answers and debates. The reality is wether one likes it or not, English became a lingua franca in science and science communication. Thus, it is the result of a historical process, a tool, and I don't see for the time being any alternative franca language.

  • Said Jadid Abdulkadir added an answer in ANN Techniques:
    Which are the techniques available to improve the performance of trained ann model?

    Trained ANN model has also some deviations as compared to the target data. how can that be minimized?

    Said Jadid Abdulkadir · Universiti Teknologi PETRONAS

    cross validation

  • Said Jadid Abdulkadir added an answer in Neural Networks:
    Any examples on Normalizing the Inputs for Neural Network learning?

    Reading the paper Efficient BackProp by Lecun and company, I need an example on Normalizing the Inputs and Choosing the Target values if anyone knows any?

    More concretely, I am interested in the implementation of said techniques.

    Said Jadid Abdulkadir · Universiti Teknologi PETRONAS

    normalize to [-1 1] 0r [0 1]

  • Virendra Kumar Saxena added an answer in Seawater:
    Anyone knows the best method to quantify resin acids in seawater?

    Considering the low concentrations present in ocean, how much water is needed for the detection?

    Virendra Kumar Saxena · National Geophysical Research Institute

    There are various methods for the  evaluation of  resin acids from sea water :

    1. Solid Phase Extraction ( ( SPE )

    2. Liquid Chromotography-  Mass Spectrometery ( HPLC - MS )

    3. Enzyme Linked Immunosorbent ( ELISA ).

    Good literature is available on these techniques. Best method has to be selected based on assay and yield.

  • Paula Croal asked a question in Acetazolamide:
    What is the ideal solvent for Acetazolamide for iv. injection in rats?

    I need to inject Acetazolamide intravenously (single dose at 21 mg/kg) in anesthetised rats, while maintaining a pH at a non-harmful level. 

    For my desired concentration of 20mg/ml, it does not dissolve in saline or 0.1M NaOH, and 1M NaOH is too alkaline (pH 11), despite good solubility.

    If I were to choose an intermediate strength NaOH, can HCl be used to lower the pH?


  • Youhong Su added an answer in FLAG-tag:
    What prevents FLAG from expression in the plasmid?

    I am having a struggle with the flag tagged expression vectors. I have constructed a flag-tagged TR using the PCMV6 myc-DDK vector from Origene. The flag tag was fused in frame at the C-terminal of the ORF of TR (stop codon removed). However, when I transfected it into the 3T3L1 cells, no expression of flag was detected. I thought it might be a problem with the vector. So I moved the ORF of TR into the sigma p3Xflag-CMV-10 vector, this vector has the 3Xflag at the N-terminal. However, still I can't detect any flag by western. And I have a flag-tagged protein as positive control. The sequencing showed no mistakes. Has anybody encountered a similar problem before?

    Youhong Su · BioCytogen

    Hi Anna Matczuk,

    What kinds of sequences do you use for a linker usually? I'm now considering to fuse a flag tag in frame with the N-terminal of the ORF of the target protein. I don't know which kind of linker should be used in N-terminal and C-terminal. Do you have any suggestions for me?


  • Said Jadid Abdulkadir added an answer in Time Series:
    I want to compare binary time series data from different instruments used during the same time period. Any suggestions on how to analyze congruence?

    I have four different instruments that recorded the the same data over the same time period and I want to compare the four different data sets to the gold standard to determine each instruments validity.

    Said Jadid Abdulkadir · Universiti Teknologi PETRONAS


  • C.P. Ravikumar added an answer in Simulink:
    How can I connect simulink with beagle bone black?

    how to interface simulink with beagleboneblack with simple program 

    C.P. Ravikumar · Texas Instruments, India

    I recommend the following blog:


  • Mohamed Mohamed Battour added an answer in Hospitality:
    What qualitative techniques will be best suited for Hospitality Research?

    What qualitative techniques will be best suited for Hospitality Research to Find out consumer preferences on Green initiatives and Why? Please share any study using qualitative techniques. Thank you.

    Mohamed Mohamed Battour · University of Malaya

    you can use semi structure interview or FGD. pls read my published paper, it may help u. all the best.

  • Marcia H. Ratner added an answer in Behavior Analysis:
    How does cognitive psychologists view behavior analysis?

    I am currently researching within a field called behavior analysis, which is essentially modern behaviorism. Researchers in this field tend to emphasize different methodologies, such as single-case designs, and often avoid statistical methods.

    In terms of psychology, behavior analysts are not interested in cognitive phenomena. This is not because they reject the existence of private events, but because they argue that cognitive events cannot be observed; only its behavioral outcomes.

    There are several papers that address how behavior analysis sees cognitive psychology. They often refer to the misuse of hypothetical constructs and unnecessary group designs. However, I was wondering if there are papers discussing behavioral analysis from the cognitive psychologists point of view?

    Most psychology textbooks will refer to behaviorism as dead, often with reference to Chomsky's critique of Skinner. According to behavior analysts, Chomsky's critique is flawed, but in mainstream psychology, behavior analysis remain a minority subdiscipline.

    So, I was wondering if there are any good articles discussing cognitive/internal/private events, and behavior analysis/behaviorism, that are written from a cognitive psychologist point of view? There are plenty such articles in behavior analysis journals, but I am wondering if the issue of cognition vs. externally observed behavior have been discussed elsewhere, from a cognitive viewpoint?

    I guess I am asking is, what papers from cognitive psychology exist that address why behavior analysis is obsolete, and internal, private events are perfectly acceptable to investigate?

    Marcia H. Ratner · Boston University School of Medicine

    If cognitive events cannot be "observed" then how does one explain the activation of different brain regions detectable with fMRI during performance of cognitive tasks?  Researchers studying anxiety and depression see differences in regional cerebral blood flow at baseline and in response to presentation of difference cues which ostensibly reflects individual differences in brain activity in response to internal stimuli and in the perception and response to the same external events respectively.

  • C.P. Ravikumar added an answer in Cadence:
    Can anyone tell me how to find reliability on cadence tool for schematic of inverter, 2 cmos gate?

    Can anyone tell me how to find reliability on cadence tool for schematic of inverter, 2 cmos gate?

    C.P. Ravikumar · Texas Instruments, India

    You have to have a model for failures and reliability before you start thinking about using a tool for computing it.  Think about what reliability of a CMOS circuit depends on. There is no one answer to a question like this. You have to come up with an answer that you find convincing and which others will also find convincing. Why are you considering such a small circuit? Your model will only be interesting when it is applied to a large circuit.

  • Le Chi Hung added an answer in Intel Fortran:
    How can i link the abaqus(64-bit) and fortran ?

    I've tried all the solutions proposed but i did not succeed.
    I've used all versions of Abaqus.

    Is there a special case that I do not do?

    abaqus versions is : 6.12-3 , 6.13-1 , 6.13-4 , 6.14-1

    Fortran : intel fortran composer XE 2013

    Microsoft Visual studio 2012

    Le Chi Hung · Dong-A University

    In addition, full installation for both VS Ultimate 2012 and Fortran XE2013 is required. Otherwise, your Abaqus will not link with VS and Fortran. 

  • Ali Al-Saadi asked a question in Metal Oxides:
    Calculate the percentage of loading catalyst?

    Dear Friends,

    How can I estimate the percentage of loading metal oxide on support catalyst such as 8% of CuO (loading) on MgO (support) catalyst, for catalyst CuO/MgO? 

    Thank you so much in advance.

  • C.P. Ravikumar added an answer in Project Work:
    Inverse of Matrix in Verilog?

    Hello Everyone,

    For my project work i have to calculate the inverse of a matrix using verilog for my project work. Any suggestion or anyone who have already done this in verilog?

    C.P. Ravikumar · Texas Instruments, India

    Your question is not well framed. What you want to design is HARDWARE for matrix inversion using Verilog as an HDL. Verilog is not a programming language.  You may want to ask why one may want to invert a general matrix in the first place. Is it for solving a set of linear equations? Can there be an alternate method for solving a system of linear equations? You will probably benefit by looking at the work on systolic arrays.

  • Peixin Du asked a question in XRD Analysis:
    How to perform XRD analysis with less sample?

    Our research group has a Bruker D8 Advance X-ray diffractometer, the clay minerals (the sample) to fill the holder is near 0.7g, but one of my samples is only 0.2g, how to do the XRD analysis and get a good diagram?

    My sample will show its diagnostic peak in low angel (2-20 degree).

    Thanks in advance for any answers and suggestions.

  • Junseok Lee added an answer in Microarray:
    Up to date, were sensitivity and accuracy of Microarray improved?

    Around 2005~2006, I think that low sensitivity, accuracy, and reproducibility of Microarray for the genes expressed at low levels were the key issues in its field. I am just wondering how highly they were improved after a decade in comparison to those in 2005-2006. It is appreciative if you get me some information on recent literatures, describing this issue. Thank you.


    Thank you so much for sincere answers. 

    In summary, it seems that there are still some reservation regarding accuracy in both Microarray and RNAseq. Additionally, neither of them seems to have better sensitivity than qPCR, especially in quantification of the genes expressed at very low levels. Does this make sense?

  • Ria Biswas added an answer in ZDOCK:
    Is it mandatory to do RDock after ZDock?

    After doing protein-protein docking using ZDock, is it necessary to perform the RDock protocol? How can it affect my results?

    Ria Biswas · University of Kalyani

     actually I am asking for RDOCK, which is a refinement program used for better scoring after ZDOCK

  • Rahimi Ali added an answer in Documentary Film:
    Does anyone know some work that would help me to study social representations in images?

    I'm looking for examples where social representations embodied in visual cultural products were studied. I found very few examples. Does anyone know some work  that help me to study social representations in  images? Is someone doing  a research of this kind?

    Rahimi Ali · Bangkok University

    Carolina, how did find the semiotic tools ? I'd like to see to what extent they represent

    cultural idiosyncrasies.

  • Dinh-Sinh Mai added an answer in Remote Sensing Applications:
    Any advice to find documents related to temperature mapping and detect minerals?

    I want to find documents related to temperature mapping, detect minerals from satellite imagery using fuzzy logic, anyone knew the source or link to download it for me please? Thanks very much.

    Dinh-Sinh Mai · Le Quy Don Technical University

    Thanks Liem very much

  • Shuichi Shinmura added an answer in Integer Programming:
    Help on Lingo Programming
    An MSc student of mine is currently working on operation room scheduling problem. She is struggling on how to convert the related IP model into Set Modeling of Lingo optimization software. Any help (an example, a modelling done in Lingo, ...) would be highly appreciated.
    Shuichi Shinmura · Seikei University

     Can you download my ICORES 2014 . In appendix, I explain the full function including SET.

  • A. Subba Rao added an answer in Fertilizers:
    Can application of small amounts of Zinc to soil increase its use efficiency in crops?

    Normally applied Zinc(Zn) use efficiency does not exceed 2-5% in crops.5-10 kg Zn(25-50 kg ZnSO4.7H2O)is applied to several field crops. Zinc uptake is in the range of 80-300 g/ha depending on crop.Some crops also responded to 2.5 kg/ha Zn.Ammonium polyphosphate containing Zn gave response in the range  0.625-1.25 kg Zn in some crops. Fortified fertilizers with 0.5% and 1% Zn are being recommended for use in some crops .Depending on the source and amount of fertilizer applied they may supply<2 kg Zn/ha.Keeping these points in view can we go for application of small rates of Zn application to soil in different crops?

    A. Subba Rao · Coromandel International

    Dear colleagues,our views  should based on some current scientific knowledge available in public domain .We can not extrapolate others views  simply based on our background knowledge.We can not easily replace the removal of  micronutrients in Indian conditions.The total  estimated removal/uptake of micronutrients B,Cu,Fe,Mn,Mo and,Zn is 179,689 tonnes.The total amounts added through fertilizers( in nutrient ) is 41,907 tonnes replacing removals only by 23%.Out of  nutrient supplied through  fertilizers, Zn occupies prime position with ,33668 tonnes.That means 80% of the micronutients   supplied is  Zn only where as Fe and Mn removal is nearly 80%.That means Fe And Mn are getting  depleted and Zn is getting accumulated.Zn is added  at 221 % percent of its requirement.Regarding  soil test based recommendations  of micronutrients,two types of research is going on in India and other countries- one determination of critical limits of micronutrients in soil and plant and second the assessing response of crops to application of 2 to 3 rates of particular nutrient .Critical limits are used for assessing the micronutrient fertility  status and response studies are used to determine more appropriate fertilizer application rate.As such  for micronutrients   recommendations response curves are not being used as in case of macronutrients. When response curves are not used it is difficult to  arrive at calibration tables or ready reckoners connecting soil test values with fertilizer recommendations.I shall be glad to go through micronutrient calibration tables/ready reckners based on response curves for any crops are  available in any   publication.The following publication provides micronutrient recommendations  different crops and cropping systems. Shukla,AK,Behera,SK,Subba Rao,A and Singh,AK.State-wise micro and secondary nutrient recommendations for different crops and cropping systems.Research Bulletin1/2012,IISS,Bhopal,Pp.1-40(2012)

  • Hamdi Ogut added an answer in Trout:
    Has anyone encountered a drowning problem in trout?

    In the last two years we are experiencing a drowning problem (not kidding:-) ) in rainbow trout in a dam lake.  Phenomenon occurs exactly at 18C and above.  Operculums are wide open and fish look contracted.    In dead fish mouths are also wide open.

    Any ideas:

    -Fish looks OK and very healthy.  No bacteria or any other disease signs interiorly or externally.

    -One of my hypothesis was that some kind of an toxic algae does that. Due to high temperatures fish may filter feed for zoo and phytoo- have observed this.

    -Cases are often one acute followed by a couple of minor hits.  In the first acute hit, highest mortality is observed.  

    -Oxygen seem no problem, I mean these are some fish in the cages not all of them, suggesting that there is severe oxygen deficiency is observed. 

    I have also checked the gills microscopically but no evidence of any severe deformity.

    One another reason could be the load of nitrit and ammonia in the Blood of fish.  Increased levels could also cause such symptoms but how come many fish could carry the same symptoms.  I only check the blood of fish for the load of nitrit and ammonnia visually..  Sometimes with a control fish from another site. 

    Any opinions are welcome.  Thanks in advance..


    Hamdi Ogut · Karadeniz Technical University

    Thanks John,

    The depth of water is about 65 m below the cages.  It would be very difficult to give air to that depth.  Never tried, but would be tried.  Anoxic water is one thing need to be considered.  This layer looks like slowly is lifted up by slow temperature increase, slow turnover , We feel it when it is close to the 10 m, then around surface 4-0m mixes up.  At that period (estimated around 10 days) fish is disturbed.  Giving air at some point would help mixing way below the cages and prevent anoxia close surfaces. 

    To overcome anoxic water below a Japanese scientist used fibed optic cables to give light to stimulate plankton growth under cages to remove anoxia.  It is a good iea to be explored further.  

  • Nripendra Singh asked a question in Grounded Theory:
    Benefits of applying grounded theory on Hospitality Research

    Please comment on the examination of grounded theory analysis with an application to hospitality research.

  • H.A. Tillmann Hein added an answer in Pain Assessment:
    Are values obtained from the visual analogue scale (VAS) reliable, sensitive and valid assessment of pain?

    The VAS was used to assess pain among a group of patients but a panelist strongly feels that the job was very poor, JUST BECAUSE the visual analogue scale (VAS) was used. Every other thing was okayed, from conception through methodology to presentation...BUT use of VAS for assessing pain was not acceptable to the panel, NO scientific backing was proffered anyway. There is need therefore to seek opinion of the science world on the VAS as an instrument for pain assessment.

    H.A. Tillmann Hein · Metropolitan Anesthesia Consultants, LLP, Dallas,TX

    In our paper " Women of Middle Age Are More Resilient to Postoperative Pain Than Young Men " (dowloadable from researchgate) we used the denial rate of PCA pumps as a more objective measure of pain.