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  • Renzo Bianchi added an answer in HRV:
    Could be allostatic stress linked with the influance of physical and mental stress on the HRV in profesional atheltes during their career?

    Allostatic stress decreased Heart Rate Variability, particularly vagal activity. May be decreased a resting vagal activity in older professional athletes (>30 yrs) combine effect of both age and allostatic stress?   

  • Is the problem with the DNA sample or did the restriction digestion not go well?


        Please take a look at the restriction digest blot I have attached here. I ran the reaction twice with changing the parameters a little but still the same result! Here's what I did:

    Enzymes used: Nhe1 and SacII. Four lanes: lane1: double digest with Nhe1 and SacII, lane2: Only Nhe1, Lane3: SacII, Lane4: Uncut. I am expecting to see two bands: 6400bp and 5700bp. But you can see there is no change between all the four lanes. I did troubleshooting after the first trial and made some changes for the second reaction but I got the same result. 

    Here's the composition of my reaction mixture: total 50 uL

    DNA -                            0.84 uL(1ug)

    Nhe1-                           1uL (10 units)

    sacII-                            0.5uL (10 units)

    10X NEB 2.1 buffer -    5uL

    6X EZ vision DNA dye- 8uL

    Deionized H2O -           34.66 uL

    This composition is for the double digest mixture and for single cuts I omitted one of the enzymes and made up the volume to 50uL. These enzymes can cut within 15 minutes but in my second trial I incubated them at 37 degrees for 30 minutes to ensure complete digest. Used 0.7% agarose gel and ran it at 4v/cm for about 2 hours. I am trying to figure out why all the lanes are showing bands of the same size when they shouldn't. I am suspecting if it is DNA methylation that is restricting the enzymes used from cutting the DNA but if so the uncut lane should be different from the rest, which I don't see. the feeling I have now is my DNA sample is not good enough and I might have to redo the Maxiprep of the plasmid. If anybody has any suggestion or clue about this please let me know. I appreciate it. 


    Maibam Singh · Colorado State University

    I ran the restriction reaction again and added the EZ dye right before loading then ran the gel for an hour and half. This time the right bands showed up and it was a success. I used ethidium bromide in my gels before and did not have to worry about the order of adding the components of the reaction mixture , therefore, I made the mixture at once including the dye and kept getting gels with no cuts. Now I realized my problem. Thanks everybody for the suggestions. I really appreciate it.

  • John S Wishnok added an answer in LC-MS:
    How to find statistical significance for qualitative proteomic data?


    I have proteomic data from LC-MS of three individual experiments. IIt is a qualitative data. I have grouped the proteins into the number of they are identified from three experiments. For example, if a protein appeared in all three expts, i give a value of 3 and if in two expts then 2 and so on. Can anyone please suggest a method to calculate the statistical significane for the list of proteins. 

    Thanks in advance.

    John S Wishnok · Massachusetts Institute of Technology

    Hi, Rakesh -

    It's difficult to answer your question without some more information.  For example, are your three experiments repeats of the same conditions, or are they three different conditions?  If three different conditions, did you do multiple analyses of each of them?  What were the experiments  (e.g., how did you identify the proteins) and what are the objectives or hypotheses?  Based on the few details in your query, it's not clear that there is an appropriate statistical approach to your data.

  • How do we know if an intersection needs a traffic signal installed?

    Hi All,

    I have been looking for a while for indicators showing the need of traffic signals in an intersection and All I have found is manuals from different states and countries and each one has it's own procedure (and not defining the actual indicators they are basing their study on in order to install traffic signals).

    So I've come to ask the elite of researchers on this matter if they could tell me If I can find a book or a standard manual showing the exact factors (more numeral than definitions) that would help me in deciding whether to install traffic signal controller and especially how many phases do I need ?

    Thank you for your help !

    Nimmi Candappa · Monash University (Australia)

    Hi Saad, Following on from your discussion with Michael about the suitability of roundabouts at intersections, there are certainly ample studies on the relative safety benefits of roundabouts compared to signals. Three features of the roundabout make it safer: a correctly designed roundabout produces adequate deflection to induce reduced speed, reducing overall KE of the crash. The deflection along with the central island produces more acute angles as opposed to the 90 degree collisions possible at signals, again affecting the overall outcome. The central island also virtually eliminates the potential for 90 deg collisions, the most severe of impact angles. In addition, conflict points are reduced from  32 to 8, reducing the overall potential of a crash at the intersection. Signals are not considered Safe System compatible.

    With respect to traffic movement, it is true signals allow manipulation of traffic, and this is difficult with unsignalised roundabouts. However, a traffic flow advantage at roundabouts is the continuous movement possible during non peak hours. For example, assuming the pivot phase at a signalised intersection is for the major road, vehicles approaching from the minor road are likely to experience some delay even when no other vehicles are present, as the vehicle  would approach on a red light, and so would still need to come to a standstill, wait for the light to turn to green and then progress through the intersection, even with no vehicles present. At a roundabout, when there are no other vehicles present at the intersection, vehicles are able to progress through the intersection directly with no delay. I do believe there are some UK counties that install roundabouts for capacity reasons, maybe worth looking that up. Also, Turbos from The Netherlands have been found to improve capacity by 20% compared to traditional roundabouts.

  • Is anyone working (Has anyone worked) on how Democratic Peace Theory can be applied to internal (not international) security, order and stability?

    I welcome suggestions/recommendations if anyone is working (has worked) on how Democratic Peace Theory contributes/does not contribute to internal (not international) security, order and stability?

    Jorge Morales Pedraza · Independent Consultant

    I would like to suggest the lecture of the paper  entitled "Democratic Peace Theory: A Review and Evaluation” www.cemproc.org/democraticpeaceCWPS.pdf · PDF file.

    It is a good theory, but no more than that, because some of their propositions such as:
    •Democracies do not make war on each other.
    •The more democratic two nations are, the less the violence between them.
    •Democracies engage in the least amounts of foreign violence.
    •Democracies display, by far, the least amounts of internal violence.
    •Modern democracies have virtually no "democide" (i.e. genocide and mass murder).

    are not valid and the concept of democracy, wars,  etc.,  are not clear and well defined.

  • How to estimate travel speed on road section on the basis of spot measures of speed?

    Do you know any methodology for extending spot speed time mean or space mean (measured by measurement stations - inductive loops) for the road section (e.g. between junctions)?

    Martin Treiber · Technische Universität Dresden

    Although seemingly simple, your question has boggled the mind of many researchers because of its practical relevance. Let me state the issues point by point.

    1. (Double-) loop detectors can only measure the time mean speed at a fixed location while the travel time is related to the time mean speed in the moving frame of the vehicle

    2. A better (though not exact) mean to determine the travel time would be the space-mean speed which, however, can only be taken by snapshots at a fixed time.

    3. The space-mean speed, in turn, can be approximated by the harmonic time mean which, unfortunately, is rarely available (though in principle measurable by loop detectors)

    4. In free traffic, time mean and space mean speed are indistinguishable, for all practical purposes. In congested non-stationary traffic, the time mean speed can be higher than the space mean (or the harmonic time mean) by a factor of two (!) and more. See Chapter 3.3. of "Traffic Flow Dynamics" by Treiber/Kesting (Springer, 2013)

    5. Now coming to the actual travel times. There are three types: (i) realized travel time (RTT) (actual TT measured at the time of finish, (ii) projected/estimated travel time (ETT) measured at starting time, and (iii) instantaneous travel time (ITT) which is the space integral over the inverse of the spatial speed. The RTT and ITT can be estimated by a series of loop detectors using cumulated vehicle counts or virtual trajectories, see Chapter 19 of the above book. The ETT neads additional short-term traffic prediction.

  • Is it possible to use non-probabilistic sampling(like Judgmental) in case of Structure Equation modeling ?

    I have used non-probabilistic(Judgmental sampling ) for my research paper based on SEM and want to know whether my result is reliable one?

  • What is the most difficult fundamental concept, formula, fact or theory to understand or accept in physics ?

    Casimir effect, Hawking radiation ,Quantum Entanglement  , Dark Energy, Zero point energy of the Vacuum . .........and so on are all part of what we deal with every day in our physics research......what do you find hardest.....to swallow 

    Mohamed El Naschie · Alexandria University Alexanderia Egypt

     Imad Ahmad Barghouthi to  MS ELNASCHIE  hour ago
    I am not happy with wave function (quantum mechanics), Lagrangian (classical mechanics), Electric field (electromagnetic theory), distribution function(statistical mechanics). We are excellent in finding these functions and in using it to get real physics, but I do not understand the physical meaning of these functions.    



  • Ian D Davis added an answer in Dendritic Cells:
    Can dendritic cells present multiple antigens in an inflammatory manner simultaneously?

    Say a DC becomes activated and presents some antigen - can it simultaneously present another antigen, whether foreign or self? If it can simultaneously present a self antigen, how does it prevent the body from forming an inflammatory reaction against the self antigen since it's an activated DC? 

    Ian D Davis · Monash University (Australia)

    Of course, this must be happening all the time: a DC is never in the situation of processing and presenting only one antigen at a time. Therefore "self" antigens must always be presented at the same time the DC presents the "danger" antigen they have just found. Other homeostatic and protective mechanisms including central and peripheral tolerance then come into play to protect against autoimmunity.

  • Sattar Hussein asked a question in Instruments:
    I need help in providing ASTM D4567 - 03(2013) PDF for surface area determination?

    our instrument is measuring single point surface area . so which ASTM is suitable for it

  • Khaled Hossin added an answer in MATLAB:
    Does any one have an example of matlab code for a genetic algorithm for optimizing and creating rules for certain dataset?

    I need to visualize how to convert a rule to binary individual for a genetic algorithm and how to start with certain initialization of populations. I also need to see an example of how genetic algorithm deal with rules. So is there a good matlab code example to start with?

    Thanks a lot. I do appreciate your time to answer me.

    Khaled Hossin · Northumbria University

    I agree with Masih

  • Till Philipp Meyer asked a question in Questionnaire:
    Does someone know how to evaluate the feasibility of, for example a fasting program by questionnaire?

    I am looking for a questionnaire to evaluate the feasibility of a fasting program after a 12 week intervention. The participants should complete the questionnaire at the last day of the program. 

  • Islam Saadeldin added an answer in Tramadol:
    Please, i would like to ask if there is a technique for counting the sperm number in rat semen relative to the epididemal tissue?

    studying the morphometric norms and anomalies of sperm cells in response to Tramadol administration

    please, i would like to ask if there is a technique for counting the sperm number in rat semen relative to the epididemal tissue

    Islam Saadeldin · Zagazig University

    Dear Ahmed,

    Please see this paper;


    you can weigh the epididymis first in (mg) to make the initial weights of different treatments equal. 

    In this paper you will see some recommended buffers, I did it before using normal saline (0.9% NaCl) and works good.

  • If mindset affects reaction to feedback, could it also affect the delivery of feedback?

    Research by Carol Dweck suggests that fixed mindset individuals react negatively to feedback. With this in mind, if a mentor has a fixed mindset, would this affect their ability to deliver feedback that is active and constructive?  Would they be more likely to respond with what Martin Seligman calls active and destructive; passive and destructive?

    Janet Hanson · Montana State University


    Are the political constraints you refer to external mandates?


  • Is it valid to perform regression with y and one x only?

    Assume I have a binary variable y and a binary variable x, is it valid to perform regression over these two variables only without including other x variables in the model ?

    Boris Forthmann · Westfälische Wilhelms-Universität, Münster

    A binary predictor is allowed in any kind of regression analysis (linear model, logistic regression, poisson regression...).

    But it is necessary to take into account the binary response in a logistic or probit regression (as pointed out by Florian). However, results will not differ much from simple chisquare-test.

  • Ahmad Bazzi added an answer in DOA:
    How can I resolve the coherent DOA estimation problem?

    How to resolve the coherent DOA estimation problem? i need brief answer asap.

    Ahmad Bazzi · Institut Mines-Télécom

    I must have mixed it with something else. 
    Yes, Martin it is true, the beamwidth of Bartlett beamformer is much greater compared to subspace methods.

  • How to calculate Total Phenolic Content (TPC)?

    Hi. Ive been doing antioxidant analysis. For the Folin- Ciocalteu, i used 0.1 samples (2g dried leaf extracted in 40ml methanol AR grade), 6ml dH20, 0.5ml Folin Ciocalteu and 3ml of 20% Na2CO3. My gallic acid standard curve is Y=14.26X. How can I calculate the GAEmg/mL for my samples?Can someone explains to me?thanks. 

    Lukasz Wojciech Wajda · University of Agriculture in Krakow

    Dear Jane,

    Firstly, you need to calculate the result from the equation that you obtained for your standard curve (x is concentration of total polyphenols and y is absorbance reading). x = y/14.26. You used 0.1 ml of your extract but the result that you obtained is expressed in mg/ml so the concentration of total polyphenols in your sample is x*0.1 ml. Total volume of your extract was 40 ml, so now you need to calculate the quantity of total polyphenols in it: 40*(0.1x)/0.1 = 40x You used 2 g of dried leaf so if you want to calculate total polyphenols in 1 g you need to: 40x/2 g = 20 x (mg of total polyphenols expressed as catechine)/1 g sample. I hope this helps.

  • Jack Silver added an answer in Toluene:
    What are the compatible solutes for HPLC c18 reversed phase columns other than toluene?

    What are the most common among them? Also what are their operation conditions?

    Jack Silver · Teledyne ISCO, Inc

    Ok- I understand now!

    Injecting toluene won't harm the column. It may harm your sample resolution.Toluene is a "strong" solvent for reverse phase, stronger than methanol. This means the sample could be carried, at least partially, through the column without interacting with the column surface. This reduces separation of your analyte from impurities. Depending on the amount of toluene, you may be able to get away with it though.

    See the link below, page 4, for an example of loading in a strong solvent. Although this is flash C18, it holds for HPLC as well.


  • Roy Youdale added an answer in Translation Studies:
    Can anyone provide some reliable online sources and document about translation quality assessment?

    I would like to write a literature review on this topic and I need more sources.

    Roy Youdale · University of Bristol


    In addition to Julianne House, you might like to look at this:

    "Towards a Dynamic Quality Evaluation Model for Translation" Sharon O‟Brien, Dublin City University, 2012. It's available as a  free pdf from here: http://www.jostrans.org/issue17/art_obrien.pdf

    All the best.

  • Can anyone help me in resolving the matrix to calculate the energy levels with Huckel methods ?

    Anyone can help to calculate with Huckel methods the matrix that gives the energies of the pro penal c=c-c=o

    Mohamed El Amine Benmalti · Université Abdelhamid Ibn Badis Mostaganem

    thanks,  your answers are quiet clear 

  • Is anybody working in CUDA language?
    CUDA C/ C++ for Windows 7 PC.
    Ahmed Hassan Yousef · Ain Shams University

    Yes, Any help??

  • Jack Silver added an answer in Toluene:
    Is anyone familiar with waters 501 HPLC solvent compatibility?

    I have an old "Waters 501 HPLC Pump" - I wanted to know what solvents this system is compatible with? I don't want to use it for LC, I want to use it as a pump for some organic chemistry flow reactions. Any ideas or a good website/reference?

    I assume it can be used for normal phase, so organic solvents should be ok, but I really wanted to know about toluene.


    Jack Silver · Teledyne ISCO, Inc

    Check that all fittings are tight. A loose fitting could cause air to be sucked into the system.

  • Raid Amin added an answer in Multicollinearity:
    How can I calculate VIF (Variance Inflation Factor) in Cox regression using R software?

    Hi, I am currently investigating the impact of D-dimer level on prognosis in patients with metastatic gastric cancer.

    Because the variable of interest was significantly associated with several covariates in Chi-square test, I think that the multicollinearity among these variables should be taken into consideration before Cox regression analysis.

    Is it possible to calculate VIF in Cox regression (R or SPSS software)?

    Raid Amin · University of West Florida

    Yes, only the predictor variables (x1-x5, above). 

  • Issue thawing embyronic stem cells?

    I am wondering if anyone has problems thawing embryonic or induced pluripotent stem cells.  In particular, I am finding that after two or three days post-thaw that the feeder layer becomes so dense that it chokes out the colonies that would have developed.  At the moment, I freeze down with feeders as these cell lines are not yet adapted to a feeder-free system.  If I get such high survival of feeders from my thawed vial, do I need to thaw on feeders?  Any advice?


  • Musa Peker added an answer in Self-Organizing Maps:
    How can I label the features in a U-matrix of self organising map?

    I am using kdd data set. And want to label all the features using a umatrix or is there any other option to do that.  Is there any function in matlab to do that?

    Musa Peker · Samandira Technical High School

    The following code can give ideas.


  • How can I compute connectivity numbers for skeletonization / thinning of 3D grayscale images?

    For binary (black/white) images, many thinning algorithms exist. However, few methods are available grayscale images, in 3D. I implemented the grayscale thinning algorithm for 2D[1], but now need to extend it to 3D. The key problem in this extension is to guarantee connectivity of the skeleton by computation of a connectivity number. Does anybody know an algorithm to compute a connectivity number for 3D grayscale image?

    [1] Kim et al., LNCS, 2006.

    Graham W Pulford · Thales Group

    Good question. I don't know the answer, but maybe it's related to clustering? You could  look at connectivity using a clustering measure in any dimensional space. I'm not sure how the grayscale affects things - but why not just bundle it into the clustering metric?

  • Noreen Gleeson added an answer in Gynecology:
    Is female sterilization using Pomeroy's Technique justified in all cases?

    As per rule/law, at least in India, we have to perform female sterilization with Pomeroys technique. But over the years, I came across several cases, where I feel this technique should not be used in some cases. For example
    Previous 3/4 cesarean section
    Previous rupture uterus and scar dehiscence this time
    Scar dehiscence without labour in previous one scar
    If we perform pomeroy's technque in these cases, there is a little chance of spontaneous recanalization, and surgical recanalization is never intended or advised in such cases.

    Noreen Gleeson · Trinity College Dublin

    Consider excising fallopian tubes or at least the fimbrial end to prevent serous cancers of ovary and peritoneum