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  • Hello evry one , hope you all the best , please I need references for MCQs in occupational health and medicine......?

    I am looking for abook containing questions and answers i occupational health , any one can help ?

    Senthilvel Vasudevan · King Saud bin Abdulaziz University for Health Sciences





  • Raheleh Tooyserkani asked a question in Neomycin:
    What is the optimal concentration of G418 for selection of HEK293-T cells?

    I've transfected HEK293-T cells with pCI as a mammalian expression vector containing neomycin gene as a selectable marker. I need to know the most efficient concentration of G418 for cell selection.

    Thank you all!

  • Iqra Tariq asked a question in Economy:
    What are the main differences between how people are managed in a Liberal Market Economy and a Coordinated Market Economy?

    Basically the main differences between a LME and CME

  • Mohit Sharma added an answer in Plagiarism:
    Is the solution to student plagiarism a greater emphasis on examinations?

    With the proliferation of online checkers it seems to be getting harder to detect plagiarism in student assignments. Exam conditions largely eradicate opportunities for plagiarism.

    Mohit Sharma · I.T.S Centre for Dental Studies & Research

    Yes, that seems to be a great idea..

  • Do you have any suggested readings on identifying key operational capabilities of service/hospitality/tourism-related capabilities?

    Thanks in advance for your replies

    Shian-Loong Bernard Lew · Taylor's University

    For a grass-roots , bottom-up approach to the identification/ formulation of operational capabilities it would probably be good to focus on how the hospitality & tourism businesses deliver value added services by holding before them the principle of: the moment of truth.Making sure that value delivery graduates the guests/tourists moment by moment, from one experience to another, in a way that leads to the ultimate moment of truth. The ultimate buy-in and NOT a superficial or premature one.

  • Adam B Shapiro added an answer in ELISA:
    Optimized serum dilution for ELISA?

    Is there any standard range or a limit for diluting the serum for ELISA optimizing? If the optimized dilution is about greater than 1:10000 (eg. 1:16000, 1:64000) and still giving a good OD value for positive control, can we take that dilution for assaying samples?


    should we optimize the assay for lower serum dilutions (like 1:500 or 1:1000) by changing (optimizing) the blocking buffer to get minimum non-specific background?

    Adam B Shapiro · AstraZeneca

    Perhaps you could prepare a standard serum in a rabbit with a high titer by extensive immunization. Of course, you would also need an anti-rabbit IgG secondary antibody instead of anti-human.

    If you don't like that idea, maybe you could get away with just 3 replicate wells/plate with your current standard positive control.

    I wonder if you might be able to use no standard, but instead use the titration curves themselves to define the response. After subtracting the background, if you plot the signal versus the serum dilution on a log scale, you should get an S-shaped logistic curve with a minimum at zero and a maximum at some positive value. The serum dilution at half the maximum could be called the titer. This method would fail, however, for samples with very low titers that never reached a maximum point.

  • Mary Bresnahan added an answer in Aversive Therapy:
    Do you believe obligation can be benevolent or is the perception of obligation always aversive?
    Kant described benevolence in obligation. Are there any situations in which people might regard being in a situation of obligation to others as benevolent?
    Mary Bresnahan · Michigan State University

    You are taking a more macro perspective.  What if a third cousin who you rarely saw and who knew you were successful asked you to house their kid in your London flat and help pay for the university tuition.  Would you do it?   Do your elderly parents live with you in your flat?  Obligation is not about personal gain.

  • Harish B M added an answer in Ligand Binding Assays:
    What can I do when I have trouble with my ligand on autock tools procedure?

    Can anyone help me on this please?
    Once the protein is prepared, when I open the ligand and try to do the torsion tree part, I get an alert box saying that I must select a ligand first. I can't understand why this happens because I already have the molecule I want selected in the left options of the dashboard. What am I missing?

    Thank you!

    Harish B M · Bangalore University

    ya, i hop, u remove water molecules and try it. or u draw molecule again, In the ligand some coordinates problem found.

  • Nikhil Sirdesai asked a question in Comsol:
    Using COMSOL Multiphysics to simulate the subsidence caused due to heating of cavity beneath the earth surface. Why am I getting an upheaval?

    I am currently working on the effects of underground coal gasification on the nearby strata. I have been trying to simulate the same using COMSOL.

    I made a model consisting of a host rock (1000m x 1200m) and a rectangular cavity (7.5m x 100m) within it, signifying the cavity left after burning of coal.

    1. First I made the model having no cavity and allowed it to settle on its own by gravity. The top boundary of the model was kept free and roller were placed on the remaining three boundaries. The total displacement noticed was 15.7 mm downwards.

    2. Next I simulated the cavity and noticed the strata behaviour. It gave expected results showing a subsidence on the surface.

    3. Now, to simulate the heating caused by burning of coal, I placed four temperature source of 1273.15 K at the boundaries of the cavity and applied room temperature conditions to the external boundaries. (See Attachment 1).

    4.The temperature distribution looks fine. As the top boundary is still at room temperature.(See Attachment 2).

    The problem started here as the whole model started behaving like a single body showing thermal expansion. The expansion was visible on the top boundary of the model, as the other three boundaries were simulated with rollers. The total displacement of the top surface is about 750 mm upwards. (See Attachment 3). The reason I am confused is, if the top boundary is at room temperature why is there a upheaval?

  • Awais Malik added an answer in Survey:
    Do you use prophylactic antibiotics in laparoscopic cholecystectomy?

    The West Midlands Surgical Research Collaborative (http://wmresearch.org.uk/)is in early stages of planning a randomised control trial of perioperative antibiotics based on data from the CholeS Study. To determine if this is feasible, we would appreciate if you had 2 minutes to fill out a survey which can be found at – Antibiotic Survey (this link may not work from hospital computers).


    We would be very grateful for your comments.

    All the best

    Ewen Griffiths on behalf of the WMRC

    Awais Malik · Services Institute of Medical Sciences

    We always do...

  • Senthilvel Vasudevan added an answer in Orthology:
    How to identify orthologous genes?

    Anybody know how to identify orthologous genes in different plants?If you can, please recommend software in windows. 

    Senthilvel Vasudevan · King Saud bin Abdulaziz University for Health Sciences


    To identify the orthologous genes, by the following links:




  • Is the remark of Richard Feynman (I think I can safely say that nobody understands quantum mechanics) still valid or acceptable?

    Regarding our current understanding of quantum mechanics, especially the interpretation of the theory of measurements in terms of parallel universes.

    Theoretical physics, quantum mechanics, Fundamental physics 

    Kåre Olaussen · Norwegian University of Science and Technology

    George> .. the role of the observer,

    Yeah, I think nobody likes the observer; the wavefunction ought to collapse in his absence. There is a spontaneous collapse theory by Ghirardi, Remini, and Weber, but I am not sure if it has any experimental support.

    I once played with a simple nonlinear generalization of QM, hoping the uncertainty in measurements  could be attributed to essentially unpredictable chaotic dynamics. It works a little bit, but it seems quite difficult to reproduce the Born probability distributions. The real obstacle is to violate the Bell inequalities without violating locality in such models; that seems impossible.

  • B.R. Rajeswara Rao added an answer in High Vacuum:
    Is there any experience in cup and saucer designed Artisan stripping column applications in an industry?

    Artisan stripping column. One unique mode of stripping column used to replace packed and other stuffed columns. 

    Question arises as, according to column applications stated by manufacturing company itself; this column can act as an desolventizer and can remove/strip off residual solvents to ppm levels. since our feed is in oleoresin form (slurry), when charged feed from top in presence of high vacuum and direct steaming, its getting sucked back through the vacuum line to the solvent receiver.

    Which clearly states that the applied back pressure is more stronger than the material sp.gravity. 

    Need suggestions for air displacement for this equipment.

    Thanks in Advance.

    Harish K.

    B.R. Rajeswara Rao · Central Institute of Medicinal and Aromatic Plants

    Dear Harish

    I found that your question remained unanswered for a long time. This is not an answer to your question but thought that you may be interested in the following link:

    Good luck

  • How to split the environmental factors from the influence of agricultural treatment on microbial communities?

    I want to evaluate the effect of different treatments on the composition of microbial community. The treatments consist in different crop rotations and I have two repetitions (communities) per treatment. Every community is characterized as number of sequence per each taxa detected. To complicate the analyses there are some soil parameters (pH, P, N..)  that are not uniform even among the repetitions. There is any kind of analyses to split the influence of environmental factors from the influence of my treatments?

    Senthilvel Vasudevan · King Saud bin Abdulaziz University for Health Sciences


    Your question: How to split the environmental factors from the influence of agricultural treatment on microbial communities?

    Kindly see the following:



  • W.J. Ubulom added an answer in Academic:
    How often do your universities carry evaluation of their academic programmers to identify the worth or discrepancies?

    It is necessary that 

    W.J. Ubulom · Rivers State University of Science and Technology

    It is important that constant programme evaluation be carried out on every academic programme for the purpose of improvement.

  • How is the gravitational potential replaced by the metric tensor in general relativity?

     How could i calculate potential difference between : infinity to a point A , (general relativity formulation). Please explain how to calculate in simple terms...i cant understand the terms used in wikipedia . 

    Luiz C. L. Botelho · Universidade Federal Fluminense


    All of yours affirmations on my remarks are totally wrong !.Read opinions carefully ,before tell STRING OF non senses .Let me give you an example of your non sense :you told that :

    "The ‘origin’ at ‘r = 0’ is NOT the origin at all, because this ‘r’ is not even a distance let alone the radius in the metric.


    Are you a student  ?.Your Mathematical Knowledgment is so "College Student Calculus "....

    Of course that r is the radial coordinate on the manifold chart of the Scwarscild Manifold problem !,which is R4 -().And the point zero is where is supposed to be the gravitational source ,Everything is somewhat a PHENOMENOLOGICAL MODEL on Schwarzchild "solution" of Einstein equations !!.

    By the way , you confuses the euclidean manifold space time (where the coordinate systems lives ) with the Lorentzinian metric (an not positive inner product on the tangent manifold space ,an object defined  at which space time manifold point !) .The "assemble" (the euclidean manifold space time with its differential EUCLIDEAN structure , added with a Lorentzian field metric on the manifold tangent space is what is caled Lorentzian Space Time-A pseudo Riemannian manifold  ) .By the way , do you know the the usual metric inverse DOES NOT ACT ON THE MANIFOLD TANGENT SPACE ?.It is a mathematical object on the dual tangent space on the Manifold .


    Related to your claim 

    "I have proven that black holes do not exist; they are the product of irrational imagination and invalid mathematics. It’s all over for the cosmologists."

    And as I have shown already, according to Einstein and his followers, material sources are alleged to be both present and absent by the very same mathematical constraint, Tuv = 0. That is impossible! Schwarzschild spacetime contains no material sources for the very same reason de Sitter’s empty universe is empty (no material sources), Tuv = 0. This fact alone is sufficient to completely ruin black holes and big bangs, bearing in mind that the cosmologists retain the former in the latter.


    I can only say that this is a ...IRRATIONAL delirium of yours .

  • How to calculate the area of the voronoi cell?

    I have to find the area difference in the voronoi cell in the adhoc network.I have attached the link of the paper.Can someone please help me in understanding the fitness function in the given paper which is finding the area difference in the voronoi cells in adhoc network.(Page 3: Fitness function)

  • Pushkar Kamble asked a question in Nitrocellulose:
    How to immobilise antibodies on nitrocellulose mebrane with easy steps?

    I need to use these nitrocellulose membranes to bind Ab specific antigens, after immobilising antibodies to it. Could you suggest any simple Ag - Ab pair to start with?

  • Does any one know which solvent should be used for the plant extract used in various antioxidant assays?

    respected sir/mam..i have been deeply troubled by one question and couldn't find any satisfying answer

    I am working on antioxidant activity of leaves.I have extracted the phenolic compounds by using aqueous Methanol.Now when i'm following the protocols for various antioxidant assays ,in some protocols dried plant extract is dissolved in distilled water and in some it is in alcohol, even for same assay..so my query is should be dissolved in Distilled water because phenolic compounds are insoluble in it or in alcohol where as in standard protocol it is dissolved in distilled water..what to do..please help...

    B.R. Rajeswara Rao · Central Institute of Medicinal and Aromatic Plants

    Check this informative link for its utility:

  • Shantanu Panwar asked a question in Omnet++:
    Can someone let me know how to code the Virtual Cord Protocol in OmNET++?

    I am trying to verify the advantage of VCP over MANETs.

  • Has a classical finite-size model of electron been found?

    Around 1951 Dirac wrote a less-known paper compared to his famous Dirac equation paper. In that 1951  paper with title A new classical theory of electrons, Dirac wrote among other things:

    "Recent works by Lamb, Schwinger, Feynman and others have been very successful in setting up rules for handling the infinities and subtracting them away, ... but the resulting theory is ugly and incomplete one."

    With that statement it seems Dirac wants to say that the quantum electrodynamics theory is incomplete and unsatisfactory. I read elsewhere that Feynman also said that QED is like sweeping under the rug.

    One problem related to this incompleteness of QED is incompatibility between quantum and classical picture of electron. Therefore Dirac's attempt to arrive at a new classical model of electrons should be appreciated.

    What do you think? Do you know whether the classical finite-size models of electron have been proposed after Dirac? Has this problem been solved?

    See: http://dieumsnh.qfb.umich.mx/archivoshistoricosMQ/ModernaHist/Dirac1951a.pdf

    Stam Nicolis · University of Tours

    It's not the fact that the electron is a point that leads to singularities in quantum field theory, but the fact that a quantum field theory describes infinitely many degrees of freedom. This is the infinity that must be defined-and renormalization theory achieves this in a way that's consistent with Lorentz invariance. incidentally, before Dirac, Heisenberg and Snyder (independently) had studied how the introduction of a minimal length might, indeed, remove the divergences in quantum field theory. These works are now recognized as precursors to the ideas of non-commutative geometry of spacetime, in the context, once more, of quantization of gravity. 

    A fixed length scale, (or energy scale, like a mass), incidentally, breaks Lorentz invariance, so care is required. 

  • B.R. Rajeswara Rao added an answer in Sulphur:
    What do changes of colour represent e.g. yellow, brown, blue on TLC plate by using 10% sulphuric acid as reagent?

    I'm use the reagent for my MeOH and aqueous extract sample.

    B.R. Rajeswara Rao · Central Institute of Medicinal and Aromatic Plants

    Check this interesting link if it is useful to you:

  • Where can i purchase antibodies for Western blot assay?

    My research team have been conducting protein profile studies  for heat shock proteins but we need to be able to quantify the induced proteins. 

  • Guenter Grundmann added an answer in Minerals:
    Why are the twinning quartz not common in thin section?

    The twinning of some minerals are relatively common in hand species,
    but not observable in the thin section scale,
    (at least in the volcanic rocks),
    my first thought is that the structure of quartz make it this way,
    but the common twinning mineral, feldspar, are also tectosilicates,
    then I thought it was because quartz are the phases that solidified last,
    making it have least space to growth in the magma,
    but I think this point is weak to explain this,
    does anyone know something about this?
    Thanks for helping in advance.

    Guenter Grundmann · Technische Universität München

    Dear Mr. Huang,

    The twin lamellae of quartz, which has grown in volcanic rocks are only visible when the crystal wafer is slightly thicker (100-500) than a normal thin sections (20-30 micron). A favorable section is perpendicular to the crystallographic c-axis of the crystal. The two accompanying sketches show the twin lamellae exactly in this section. The attached photomicrograph shows in transmitted light between crossed polarizers such twins in a quartz crystal that grew in an altered basalt. The wafer of this quartz crystal is about 500 microns thick. The twin lamellae are inclined to the plane, so they appear blurry.

    Best regards,

    Guenter Grundmann

  • B.R. Rajeswara Rao added an answer in Aloe Vera:
    Hi, I need help to defat samples before protein extraction. Should I treat seed samples with hexane only or fresh samples also need treatment?

    Hi, I am going to freeze dry samples prior to protein extraction for transport to some other destination. As seeds contain so much oil these are treated to defat them before protein extraction.I am going to treat seed samples with hexane in 1:3 and then drying overnight under fume hood. I have some fresh parts of plants as well. Do I need to treat them the same way or not as they contain a lot of liquid inside. Thanks. I am using aloe vera as well and its totally liquid.

    B.R. Rajeswara Rao · Central Institute of Medicinal and Aromatic Plants

    Check this informative link on isolation of plant constituents:

  • Manuel García Ávila asked a question in Sahara:
    Anyone have this papers?


    I am looking for this papers and I can not find them:

    Struve, Wolfgang. 1990. Palaeozoologie III (1986-1990). Courier Forschungsinstitut Senckenberg, Abb. 1-9; Frankfurt am Main. 127, 251–279.

    Struve, Wolfgang. 1995. Die Riesen-Phacopiden aus dem Maider, SE-marokkanische Prae Sahara. Senckenbergiana lethaea, 75, 77–129.

    Anyone could send me them please?


  • How can the size of nanoparticles synthesized by Chemical method be controlled?

    We have synthesized the ZnS   as well as   metal doped ZnS  nanoparticles by chemical  wet method. But the size of the particles are not uniform ; ranging from 2-3nm to 100nm  as observed by TEM annalysis.