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  • Milan Pabst added an answer in Action Potentials:
    Why is a change of the pipette resistance normal , when I give a positive pressure?

    Hi, I used to work with Cs-based internal solution(Cs-IS). Now, I change to K-Glu based internal solution (K-IS) to record action potential. When I use the K-IS, I found the pipette resistance can change from 3.5M to 4.3M after a positive pressure, but not Cs-IS. When release the positive pressure, the pipette resistance change back to 3.5. I checked the pipette there is no air bubbles or dirty things clog the pipette.

    I also checked the osmolarity of K-IS, it is about 285. It should be OK.

    I am not familiar with K-IS. Is this normal?

    Milan Pabst · University of Bonn

    Hey Mason,

    the increase in resistance is normal, a possible reason for that is explained by Carlo. So, don't worry about the resistance. Usually people don't see it because they apply pressure already before they introduce the pipette to the external solution. 

    One possible way of eliminating bubbles in your patch pipette is pulling your patch pipette from borosilicate glass with filament. Then you put a drop of your filtered IS to the opening of the patch pipette (not the tip ;)) and than the trick is to use the capillary action of the pipette glass to pull the IS into the very tip of the patch pipette.

    If you have dye in the IS you will than see the dye in the very tip of the pipette (you see also IS w/o dye but to try it it might be easier with dye... ;)).

    Cheers, Milan

  • Srinivasan Venkatesan added an answer in Electrolysis:
    Is electrolysis a common process in Nature? What minerals might be involved and what electric manifestations have been observed?

    When protecting steel structures against corrosion in the sea, the common practice is to use sacrificial anodes made form Zink. The Zink is corroded instead of the steel and subjects the steel to a constant flow of electrons that prevents Oxygen binding to the steel.

    The side effect of this electron current is the splitting of water molecules into Oxygen and Hydrogen. The Hydrogen may lead to steel embrittlement as it invades the steel structures. But, the question is: can somebody envision a similar process occurring naturally in some mineral/subsurface settings? Does anyone know whether similar electric currents, occurring naturally in the subsurface, may lead to the production of Hydrogen? What minerals might be involved and what electric manifestations have been observed?

    Srinivasan Venkatesan · Energy Power Systems LLC

    All the above comments are valid and true.  In nature bacteria related corrosion on underground structures is known.  Many of these structures are oxide covered but the corrosion reaction goes on. Sulfide contaminated sub surface regions undergo corrosion via bacteria using similar mechanisms.  Hydrogen evolution and consequent embrittlement are common.

  • Vivek Arora asked a question in Vorticity:
    Formation of bigger and smaller eddies in turbulent medium?


    I have a question on turbulence.

    Turbulence causes the formation of eddies of many different length scales. Most of the kinetic energy of the turbulent motion is contained in the large-scale structures. The energy "cascades" from these large-scale structures to smaller scale structures by an inertial and essentially inviscid mechanism. This process continues, creating smaller and smaller structures which produces a hierarchy of eddies. Eventually this process creates structures that are small enough that molecular diffusion becomes important and viscous dissipation of energy finally takes place. 

    Now if i consider a case where a stirrer is rotating with certain speed. Liquid will be having a big vortex and some small vortices.  Now if the stirrer speed remains same, bigger vortices will always remain in the same size and it will never form smaller vortices. Then how the energy transformation takes place? Whatever smaller vortices are there in the medium, they are not due to the breakage of big eddies, they are formed due to turbulent medium. And the energy is transferred from the bigger eddies to smaller ones due to shearing action?

    Existance of smaller eddies does not depend on the bigger eddies and they are not formed from the breakage of bigger eddies?

    I know my perception may be wrong, but where is the mistakes?

    Please someone answer.



  • Gordon Chirgwin added an answer in Eccentrics:
    I need help calculating the Plastic resistance of an eccentrically loaded CFST Column?

    I need help calculating the plastic resistance (Squash Load) of an eccentrically loaded concrete filled steel tube column. EC4-1-1 did not give a very good explanation on how this could be achieved. i will really appreciate a reference where i can get this equation from.

    Thank you.

    Gordon Chirgwin

    So the axial load is reduced due to load eccentricity using the factor.  Then you back calculate the moment using the reduced axial load.

  • İbrahim Türkel added an answer in Lactic Acid Bacteria:
    Can lactic acid bacteria grow in Blood Agar?

    is it true or false that i want to inoculate lactic acid bacteria to the blood agar for growth then store at -20C in MRSBroth + gliserol. Because generally lactic acid bacterias grow at M17 agar or MRSA agar. Hope i explain my question

    İbrahim Türkel · Amasya University

    Thanks for answers. My main goal is to differate luconostoc, pediococcus etc.

  • Amitabh Shukla added an answer in Yoga:
    What are the therapeutic uses of Surya Namaskar?

    Few Days ago during International Yoga Day (21st June) some of the news channels came with the debate whether one should practice Surya Namaskar or not? The question is relation to the answer of that debate whether Surya Namaskar is related to any religion or it has some scientific bases?

    Surya Namaskar is the combination of 12 Yoga postures. Several articles emphasize  that it is useful for physical fitness and hormonal balance. 
    Is there any scientific study over it which proves the statement?

    Amitabh Shukla · Global Institute of Management & Technology

    we were  expecting that Dr K Kumar has provided an opportunity to know more & deeply about the benefits of Surya Nemeskar. But , so far , neither he has provided nor we could receive any detailed analysis on the issue i.e. a very relevant and good theme.

  • Kareem Ahmed added an answer in Video Processing:
    How can I extract frames out of a video?


    I have used the following Matlab code to extract frames of a video, however, in the folder in which the frames are stored I see that after every five frames (for example), three frames are entirely black (the background of image)!! and this is seen when I change the video but for example the numbers of five and three are changed to others....

    How can I resolve this problem? I really don't want this happens since some data will be missed undesirably...

    my code is : 

    % Open an sample .mpg file

    [FileName,PathName] = uigetfile('*.*','Select the Video');

    file = fullfile(PathName,FileName);

    %filename = '.\003.AVI';

    mov = VideoReader(file);  % make an obj of video (with all video info)

    % Output folder

    outputFolder = fullfile(cd, 'test');

    if ~exist(outputFolder, 'dir')



    %getting no of frames

    numberOfFrames = mov.NumberOfFrames;

    numberOfFramesWritten = 0;


    for frame = 1 : numberOfFrames 

        thisFrame = read(mov, frame); 

        outputBaseFileName = sprintf('%3.3d.bmp', frame);

        outputFullFileName = fullfile(outputFolder, outputBaseFileName);

        imwrite(thisFrame, outputFullFileName, 'bmp');   

        progressIndication = sprintf('Wrote frame %4d of %d.', frame,numberOfFrames);


        numberOfFramesWritten = numberOfFramesWritten + 1;


    progressIndication = sprintf('Wrote %d frames to folder "%s"',numberOfFramesWritten,outputFolder);


  • Sheeraz Ali added an answer in Cluster Sampling:
    Can I use Cluster Sampling for a mixed method research study on reading discourse skills?

    I am working as a Lecturer in a Government college of Sindh Province, Pakistan. The students of twelfth grade are taught English as a Compulsory subject from tenth grade up to graduation level.  The compulsory course of English is old and outdated. It has been taught through Grammar Translation Method as part of classroom practice.

    There are 250 intermediate colleges in five major regions of Sindh Province, I belong to Lakana region which has further divided into five subdivision or districts. 

    For collecting data from participants, I would like to make use of cluster and stratified sampling to focus on the participants belonging to my home district. This district (Shikarpur) has four intermediate colleges.

    Sheeraz Ali · C&S Degree College, Shikarpur

    Dear All,

    I am grateful to your response on the question or problems faced by me. I am Planning cluster sampling for the sake of convenience and access. However, the number of respondents may be increased because each college enrolls more than one thousand students.   

  • Hao Qi asked a question in Nanoparticles:
    How to calculate the binding energy between two nanoparticles and between one nanoparticle and the substrate?

    I want to use spin-coating technique to fabricate silver nanoparticles array.  However, usually the particles tend to aggregate.  I want to know if the binding energy between particle/substrate is higner than particle/particle, will the particles distribute evenly on the substrate surface?

    And, if the substrate surfrace is not flat but a nano-hole array, how to canculate the binding energy between the particle and substrate.

  • Mary Durfee added an answer in Paradigm:
    Is anybody doing research on the influence of paradigms on policies?

    For the past two years I have doing research on the influence of paradigms on policies, and I would like to connect with others who are doing similar research.

    Mary Durfee · Michigan Technological University

    You ever read : The Harsh Facts of Hydraulics: Technology and Society in Sri Lanka's Colonization Schemes
    Bryan Pfaffenberger
    Technology and Culture, Vol. 31, No. 3 (Jul., 1990), pp. 361-397 

    I think you might find it relevant as you think through all this. At the very least it is interesting.

  • Cornelis Roelofse added an answer in Qualitative Methods:
    Do you include your interviews and observations when writing a qualitative case study?

    I am writing a 3 chapter final for Research in Education and I want to know if I should submit my interviews and observations, not just refer to them?

    Cornelis Roelofse · University of Limpopo

    ·       Your request is limiting in the sense that i cannot gather which kind of research report you are writing but these atre my general observations; Use thematic analyses to create themescontained in the data.E.g.

    ·         Become familiar with the data

    ·         Generating and organising initial codes

    ·         Reviewing themes

    ·         Defining and naming themes

    ·         Producing the report

    Then it will depend on the number of rspondents/ cases/files etc you interviewed/analysed. Data can be presented both narratively and quantitatively.

    in narative data you may initially describe an observation or number of observations and then conclude with a finding on each theme.

    In cases of interviews use strong arguments/answers and also dissenting opinions to formulate your arguments Use direct qoutations here and there. For example:

    Interviewee #3 stated that. "...the quality of education is enhanced by..." This was confirmed by respondents 11, 14 and 7 others.

    This point has been confirmed by 75% of the interviews with 15 percent not venturing an opinion while 10% believed it is rather due to a stimulating curricullum.

    On another level you may state that:

    Analysis of data on educators’ years of experience and learner stimulation

    respondent      statement    generally agrees    generally disagrees

    1                        said that......                  x

    2.                      is of the opinion....         x

    3  etc to #10     explained that .......                              x

    ·    At the end you can summarise  what percentage generally agrees   and who not.

     Summarise each theme with  observation that confirm your conclusion/findings

  • Srinivasan Venkatesan added an answer in Electrolysis:
    How do I set-up two compartment cell for cyclic voltammetry?

    Can anyone refer to articles on setup for the two compartment cell CV? I have seen "working compartment with working electrode and reference electrode" and second compartment with counter electrode. Another set up refers to first compartment with working and counter electrodes and the second compartment with reference electrode. Which one is it? Is the setup for CV and bulk electrolysis the same?

    Srinivasan Venkatesan · Energy Power Systems LLC

    I agree with Nataliya V Roznyatovskaya . It is customary to have the working electrode and the reference electrode in close proximity ( i.e in the same compartment).  To isolate the products of reaction , the counter electrode is located in the second compartment. The commercial reference electrodes do have a glass frit that isolates the offending anions.  The main point is to locate the reference electrode very close to the working electrode either directly or through a Luggin capillary.

  • Marcel Gaj asked a question in Vadose Zone:
    How can I calculate transpiration rates from climate data as input for an unsaturated zone Model?

    Climate data, soil moisture and isotope depth profiles are available. However transpiration rates and root distribution are big unknowns. I am using Soil-Litter-Iso (SLI).

  • Viviana V Rivera added an answer in Spores:
    How can I cryo-preserve my magnaporthe spore solution in -80 without making fresh spore suspension each time?

    I want to preserve Magnaporthe spores in a stock solution (e.g. skim milk-Glycerol, or trehalose  ). Could someone give me some suggestion?

    Viviana V Rivera · North Dakota State University

    Make sure your spore will germinate after store them at -80C in glicerol, Some species do not store well in glicerol

  • Holly Nelson-Becker added an answer in Spirituality:
    Is spirituality and spiritual well being the same?

    I want to know if both these concepts mean the same so I can decide which concept I want to use as a variable in my research. 

    Holly Nelson-Becker · Loyola University Chicago

    Partly the answer to your question above is contingent on your research question--what you want to learn from participants.  Spiritual well-being would be a much tighter and more objective, hence easily measured, variable as Cinar indicates. This is particularly true for a quantitative study. Spirituality is a broader construct that can have many aspects such as spiritual beliefs, spiritual behaviors, spiritual support, etc. It would be better measured quantitatively with a scale, though both can be (and have been) scaled. Spirituality also does not preclude suffering which would be one antithesis of spiritual well-being.

  • Alevtina Evgrafova added an answer in Neonicotinoids:
    How can I test the amount of neonicotinoids in soil?

    Are there any tools or innovative ways in measuring the amount of neonicotinoids, in particular Imidacloprid in the soil?

  • Surender Pratap added an answer in Graphene:
    Fermi energy in Graphene nano ribbons?

    I am simulating graphene nano ribbons,and i want to add my magnetic field term in Hamiltonian,is there any other method than Pierls Substitution or not.


    Surender Pratap · Birla Institute of Technology and Science Pilani

    Thanks Simchi,if we'll go beyond third nearest neighbour then what will be the expected outcome.Broadening and selfenergies should be affected as i understand ,what do you think over it sir,I am following Ferry and Goodnick for this.


  • CJ Cabilan added an answer in Critical Appraisal:
    What critical appraisal tools for systematic reviews of observational studies (cohort, cross-sectional, etc) do you use in your studies?

    Hi, I am looking critical appraisal tool for systematic reviews of observational studies. I just realized that it must be different from tools appraising systematic reviews of experimental study designs. Do you know if critical checklist of Johanna Briggs Institute could be used for such studies?

    CJ Cabilan · Princess Alexandra Hospital (Queensland Health)


    This site is a starting point. Unaware of JBI Critical Appraisal tool of SRs, but in our workshops we use the CASP tool to appraise any systematic reviews. 

  • Elizabeth León Mayer added an answer in Business Psychology:
    A leader who get high results for the company necessarily have to be a psychopath?

    Some shareholders have the conviction that it is necessary to hire CEOs with psychopathic characteristics for highly profitable results . How much of this perception has empirical basis ? Is an exaggeration ? There is some truth in this belief?

    Elizabeth León Mayer · National University of La Plata

    Not necesarilly. It is possible that he or she might have some traits necessary to get high in any activity, but they are not necesarilly psychopath. A psychopath has a constelation of traits. These traits must be diagnosed by specialist, and not by external signs only. 

  • Edmund Pool added an answer in Peritoneal Lavage:
    Why does serum has jelly-like consistency after separation in my experiment?

    There's this problem I have been getting while separating the serum from blood collected from mice by terminal bleeding from heart. I collect 0.5-1.0ml blood, keep it in ice until centrifuguation at 8000rpm for 5min on table top centrifuge. In some of the tubes, the serum is completely jelly like while in others it is completely fine.

    Has anyone been through similar problems? What could be the possible explanation for this observation? 

    I also have the same problem with peritoneal lavage collected with 2ml of normal saline.

    Thank you.

    Edmund Pool · University of the Western Cape

    The jelly like appearance is due to clotting.  You can prevent this by collecting your blood in heparin tubes.  For peritoneal fluid, collect in saline containing heparin.  Use the concentration of heparin recommended by supplier as anti-coagulant.

  • David Fairen-Jimenez added an answer in BET:
    What does negative volume adsorbed mean in BET analysis?

    I got some BET results. When i plot the relative pressure (P/Po) against the volume adsorbed the curve goes to negative (below the x axis). What does this means. And after a certain point the desorption curve is below the adsorption curve. It should have been the opposite. Can somebody please help. I can send the xcel files if somebody is interested to help analyse the data.  

    David Fairen-Jimenez · University of Cambridge

    The sample is surely non-porous, so all these problems are noise coming from the experiment. You would need to have a larger amount of sample for the analysis, take special care during the He calibration (dead volume is probably slightly wrong, and this makes a difference for very low surface areas), etc.

  • Heath Demaree asked a question in Exploitation:
    Does anyone know of any good objective measures of exploration versus exploitation?

    The n-armed bandit seems to be the most popular method to assess exploration versus exploitation, but I'm interested in learning about others, too -- especially those that might be easier to administer.

    Thanks in advance for any information you may be able to provide!

  • Graham Tunnadine added an answer in Fine Arts:
    Is it possible to establish an objective uniform gradng scheme for different jurors in works of fine arts, sculpture and architecture?

    Grading the works of fine arts, sculpture and architecture by different jurors is often more subjective than objective. Please/ what are your suggestions and opinions.on how to grade creative works objectively?

    Graham Tunnadine · University of Westminster

    Isidoro Arroyo Almaraztyr this link:


  • Fabio Narducci added an answer in Cluster Analysis:
    How might I objectively estimate the density of a set of points?

    Maybe my question sounds trivial, but I have some coordinates in a XY plane representing points of interest on an object and I would like to estimate their density in order to perform some "intelligent" actions when working with them. Basically, I only have to judge if they are too dense or sufficiently sparse to enable different visualisation strategies of virtual info.

    Can anyone give me insights? I read something about Lebesgue measure but I am not sure if it is a too strong measure for a simple case like mine. I do not have to work with thousands of points. Maybe a solution to my case is a simple mathematical operation. I only want to objectively estimate how much a point is close to others so that I can decide the proper action to perform.

    Thank you.

    Fabio Narducci · Università degli Studi di Salerno

    Thank you Antonios and Ashar.

  • S. Thanigaivel asked a question in Separation:
    How to fractionate the most promising individual compounds from the crude extracts?

    i want to know the easiest and less expensive compound fractionation or separation methods and its most commonly usedtechniques to ascertain the invitro activity of the separated compounds

  • Hosahalli S. Ramaswamy added an answer in Cereal:
    What is the effect of high-pressure treatment on fat content of cereal flour?

    We are testing various cereal and legumes under high-pressure and observed that crude fat decreased significantly after pressurization (600 MPa). Is there any explanation?

    Hosahalli S. Ramaswamy · McGill University


    I misread your question as fat content increasing rather than decreasing. Sorry. Decrease can happen due to many reasons - hydrolysis could be the possible reason. Complexing with proteins and other macro molecules could be another. Bound lipids may not be easy to measure and when that happens due to HPP you could a register a lower fat content?. I am also curious as to how were they HPP treated? Did you measure any enzyme activity like lipase?