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  • Sujit K. Biswas asked a question in Boost:
    Is a Quadratic boost converter really advantageous compared to two cascaded boost converters ?

    In two-stage Cascaded Boost converter, there are two switches, but one has low voltage + high current while the second has high voltage + low current. In Quadratic converter, the single switch has high voltage (highest voltage) + high current rating (sum of two switch currents), making the MOSFET more expensive and lossy.

  • Sven Reister added an answer in Pull Down Assays:
    How can I analyze by mass spectrometry an intact protein isolated by a pull-down assay?

    Hi to all,

    I'm trying to analyze by mass spec. a DNA Binding protein having a particular conformation, so I'm interested in isolate it and analyze it as intact by mass spectrometry. 

    I've tried to elute the protein with a buffer having 100mM of Glycine at pH 2 and giving a brief boiling (a couple of minutes).

    I know that the elution works because I've assayed it by a western blot.

    The problem is that although a desalting passage, although I eliminated every possible detergent (Tween 20 ......) I always see in my spectra the signal of a PEG-Polymer. 

    Does anyone have any experience?

    Sven Reister · Heinrich-Heine-Universität Düsseldorf


    the elution for us is done by our mass spec facility. But your can do things like electroelution in a suitable buffer ( like blotting also moves your proteins). Have a look onine there are noumerous protocols.

  • Fadel Djamel added an answer in Comics:
    What are the fictional characters (people) from the literature, legends, comic books, movies ... that had an important place in your life ?

    Let's go back for a moment in a childhood, adolescence and peek in our memories ...

    Fadel Djamel · Université Mohamed Chérif Messaadia de Souk-Ahras

    My childhood was steeped in both crops. That of the French colonization therefore I was enthralled by the tales especially "Red Riding Hood". Across my country in the grip of a revolution in both underground and cities against colonialism arouses in me the character of the heroic revolutionary that we formerly called "fellagha"

  • Osama Arafa added an answer in Radial Artery:
    Does any one still do radial artery grafts for a coronary bypass?

    What is your experience?

    Osama Arafa · University of Oslo

     Dr Khaled, >>> regarding String sign>>>>so long we do coronary  cath only for patients who raise a suspicion of PO recurrent ischemia, It is a limited number and can not give clear answer from our material, but we expect that few grafts will occlude, or go spasm., we are very strict to apply radial graft on targets with critical stenosis and good run off, we also strict to postoperative vasodilators and early antiplatelet beside avoiding manipulation of the graft during harvest, >>hoping to share in organized study soon

  • Karima Akool Al-Salihi asked a question in Ruminant:
    Does anyone have any idea about the toxicity of Scorpiurus muricatus plant in ruminant?

    Eight buffaloes some of them were pregnant , had eaten mixed green forage, one of these plant was eaten for the first time. Four hours later, animals develop signs of loss of appetite weakness, inability to stand, constipation, no rumen contraction and death . 
    The plant was named as Scorpiurus muricatus?????????? I am not sure

    Does anyone help in diagnosis?

  • Carlos La Rosa added an answer in Nanocomposites:
    Any suggestions on the problem in Arsenic Detection in Carbonate Buffer?

    I am trying to detect arsenic using MnOx/Au nanocomposite by LSVAS using following parameters.

    Vdeposition = -0.7 V

    Stripping V= -0.6 to 0.3 V

    scan rate = 100mV/sec

    Electrolyte: Carbonate buffer (pH = 10)

    But I am not getting results specific to As in stripping scan (results attached). Also I am not seeing any peaks specific to As (III) oxidn/reduction in CV as well.

    Kindly suggest.

    Carlos La Rosa · University of the Andes (Venezuela)

    Dear Pooja. I have not forgotten you. I have been having a cold and could have read thoroughly the publication. If you want to check it, I suggest you to insist. The results are late in going out when it is begun. Do not feel conquered. The scientific investigation always is desert to the beginning. But then, it transforms in deep satisfaction. The procedure of preparation of the electrode is the key. The authors know very well what happens in ácid media., the same you have observed "the acid dissolves the electrode. I suggest you check carefully the whole procedure, bearing in mind that the authors will not write meticulously the whole procedure, for what you were meeting emptinesses. Write to me how you have realized every step in the process of preparation of the composite.Greeting

  • Lisandra Angulo added an answer in Emotion:
    What do you think about categorization of emotions as negative, positive and neutral?
    I'm interested in a simple but comprehensive way of emotions categorization for an instrument that I'm developing that assess the emotional body experience. I will be grateful for any reference that could help me. I'm reviewing Eckman's classification, the Somatic Markers hypothesis of Damasio, Arnold, M., Polivy, J., The PANAS scale, Watson; the Circumplex Model of Affect, Watson & Tellegen, 1985; etc.
    Lisandra Angulo · Central University "Marta Abreu" of Las Villas

    Estimada colega en nuestras investigaciones asumimos una distinción entre emociones negativas /positivas y placenteras/displacenteras. El miedo la ansiedad, etc, por ejemplo, son displacenteras, pero alcanzan un caracter positivo o negativo en dependdencia de la congruencia con la situación, sus efectos para la salud y el bienestar y sus posibilidades para la adaptación ante el problema. 

    Emociones: procesos afectivos  que emergen de la relación entre la persona y su medio social. Conllevan cambios a nivel fisiológico, motor o conductual expresivo y subjetivo-experiencial, que tienen en su base la valoración personal de la situación o estímulo (externo o interno) y son vivenciados con agrado y/o desagrado, considerando su vínculo con las necesidades y metas individuales. Estos cambios presentan implicación para el funcionamiento biológico, psicológico y social del sujeto (Pérez.2014).
    -Emociones positivas: son aquellas que, en relación con la situación, son capaces de generar respuestas adaptativas congruentes con la misma, favorecen la resolución de problemas, consecución de metas y son potenciadoras de la salud (Fredickson, 2001; Roca, 2014)..
    -Emociones negativas: Son aquellas que generan respuestas inadapatativas, incongruentes con la situación, que entorpecen la resolución de problemas y la consecución de metas y afectan la salud (Fredickson, 2001; Roca, 2014).
    -Emociones placenteras: ocurren si la experiencia subjetiva es percibida como agradable, cuando la persona experimenta atenuación en su estado de malestar, consigue alcanzar metas determinadas, o evalúa el evento o estímulo como favorable con la consecución de las mismas, proporcionando disfrute, relajación y bienestar. Tienen carácter positivo o negativo.
    Emociones displacenteras: se generan ante acontecimientos que son valorados como dificultad para el logro de los propios objetivos, es decir, cuando se bloquea una meta o ante una amenaza o pérdida; generalmente son vivenciadas con desagrado.Requieren especialmente de la movilización de recursos afectivos, cognitivos, fisiológicos y comportamentales, que contribuyan con la resolución o alivio de la situación que las provoca .Tienen carácter positivo o negativo.

  • Sopan Kharat added an answer in Contamination:
    How do I erase the internal contamination in leaf explant (PTC)?

    How do I erase the internal contamination in leaf explant?

    Sopan Kharat · The Institute of Science, Mumbai

    Thanks to all

  • Ricardo Matias added an answer in Data Integration:
    Are there any available datasets for data integration problems?
    Instead of doing a simulation, I need a dataset with hundreds or thousands of records distributed over multiple data sources. I need it for data integration purposes where the same entity may have multiple records in different data sources.
    Ricardo Matias · Instituto Politécnico de Setúbal

    Hi Mohamed,

    Here are some links on big datasets available for free. I hope it helps you:

  • Kathleen Salse added an answer in Tai Chi:
    Does anyone know of published studies on aerobic activities vs anaerobic activities increasing cognitive function in older adults?

    I am unable to find published clinical studies regarding:  In the female older adult (65 & older) will aerobic versus anaerobic activities increase cognitive function?  Aerobic act- meaning cardio exercises (aerobic exercises, running, step-machine, bicycling)  Anaerobic act. - meaning yoga, stretching exercises (tai-chi), playing cards, Sudoku.

    Kathleen Salse · Loyola University Chicago

    Thank you Davor, I have delved more into my question, I realized I was using anaerobic incorrectly.  I had switched gears to try find the correct term but not successfully as non-aerobic does not seem to cover activities such as, yoga, tai chi, Sudoku either.

  • P. S. Kaplya asked a question in Matrix:
    I'm looking for the solution of the matrix equation dX/dt + AX+BXC=Q, any ideas?

    I'm looking for the solution of the matrix equation: dX/dt + AX+BXC=Q where A,B=[NxN], C=[MxM], Q=[NxM].

  • How to define RD, TD and ND, while doing EBSD ?

    During EBSD we have to define RD, TD and ND of the sample. If i have a sample which don't have rolling direction e.g. in case of a uniaxially deformed sample, how should i define those axes ? If ND should be the axis of deformation, then what about RD and TD ?

    Raúl Bolmaro · Instituto de Física Rosario

    Remember also that you have another intermediary problem: The way the software deals with the orientation axes.

  • Marlina Elburg added an answer in Xenoliths:
    Is there any example for magmatic Al-spinel (Cr-poor) deposits?

    I am wonder if there is any scientific or economic study for Al-spinel deposits (mostly Cr-poor, Cr2O3 < 1 wt.%). In most known cases the chromite deposit is a Cr-rich or Al-rich chromitites (Cr is essential constituent) in ophiolitic/layered intrusion ultramafic rocks or as micropods in a mantle xenoliths. Will appreciate very much if any one have any information about macro- or micropods of Al-spinel deposits in mafic-ultramafic rocks/xenoliths.

    Marlina Elburg · University of Johannesburg

    Even for a mantle cumulate, they seem to be very Cr-poor. Perhaps you should have a look at the GeoRoc website (http://georoc.mpch-mainz.gwdg.de/georoc/), where you can find a precompiled file with spinel analyses to see whether you find a match.

  • How can the privacy and security of electronic resources in academic libraries be enhanced?

    How best can this research question be handled?

    Robson Eisinger · University of São Paulo

    Good point, again. As you said, that depends on what you need to protect. If the problem here is just access control and the user can find the same content in the open web (piracy or another source, for instance), considering how complex are those security measures, I agree that most of the users will prefer the "easy way" to obtain those data. I'm saying piracy because any content that needs to be protect from unauthorized access maybe has copyright or a license to be used (considering e-resource). Here at USP most of the e-resources have open access Campus-wide and any user can access from home, using our VPN to access. So any access to those content are made using our network. Anyway, that depends. I'm against piracy, but we need better ways to share knowledge and you are right, we need to rethink own we handle this matter.

  • Mesut Tez added an answer in Genetics:
    Do transposable elements (TEs) indicate that cancer is an adaptation mechanism?

    Approximately 45% of the human genome is comprised of TEs.  TEs are not simply "junk" DNA. The effects of TE insertion in the genome varies from negligible to disease conditions suh as cancer. On the other hand;TEs activity can play an essential role in the host response to stress, facilitating the adaptation of populations and species facing changing environments.  Enhanced TE mobility has to be sufficient for generating broad genetic variation within the host genome, and that this genetic variability is genetically transmissible to the next generations.

    Mesut Tez · Ankara Numune Training and Research Hospital


  • Debasis Nayak asked a question in Sintering:
    What are the sintering steps to get dense LiCoO2 pellet by Spark plasma sintering?

    I need the holding time and temperature (all steps) to get dense LiCoO2 pellet by Spark plasma sintering

  • Amlan Chakraborty added an answer in SEC:
    Is my gene amplifying?

    I have a gene(wild type) cloned in pBAD18 Kanamycin resistant plasmid. The gene is 2185 bp. And the plasmid is 5437 bp. I wanted to insert a 6X His tag at the C-terminal end of the protein of this gene. I found that the last codon codes itself for a His. So I followed the general method for designing a primer i.e.: Last codon(CAT)-6X His codon (CAT or CAC)- Stop codon-XbaI recognition sequence. The primer length is 30 bp with a Tm of 62 degrees approx and the forward primer I used was 28 bp and has a EcoRI recognition site with Tm 59 degrees approx.
    I have tried amplifying my gene using a gradient PCR vaying the annealing temperature (see gel image). I expect to get the product in between 2Kb and 3Kb(2203 bp). But I have a range of variation in amplification above 10 Kb. What is getting amplified is my question? Is my gene at all getting amplified? I dont think so. What is going wrong.

    I am using Pfu polymerase with 30 steps amplification. I have done gradient PCR with variation in annealing please see gel image attached. PCR program:
    Initial denaturation: 95 degree- 3 min


    denaturation: 95 degree- 30 sec

    annealing: gradient- 55- 64 degree- 30 sec

    extension: 72 degree- 3 min 30 sec

    Final extension: 8 min

    Store: 4 degree.
    Notice the amplified product that I am getting is above 10 Kb.- DNA Ladder used is 1Kb NEB ladder.
    please suggest ways I can get my gene amplified for cloning. I want my insert to have a 5'-EcoRI and 3'-6X His-XbaI.

    Amlan Chakraborty · Amity University

    But, if you see my primer design the pBAD18 plasmid has a XbaI and my primer actually binds to the 3 bases there and the XbaI site, with the 6X His tag bases in the middle. Can this be a fault?

  • Priyajit Jash added an answer in Graphene Oxide:
    How can I remove the excess of hydrazine monohydrate from graphene oxide suspension in water after completion of reduction?

    I am attempting graphene oxide reduction in solution phase. How can I remove excess hydrazine monohydrate after completion of reduction? And what should be the optimum pH of graphene oxide suspension in water for reduction using hydrazine.

    Priyajit Jash · Indian Institute of Science Education and Research Bhopal

    copiously washed with water after that washed with methanol

  • Ana Paula Hermont asked a question in Dental Caries:
    Does anyone know if there is any association between dental caries and bulimia? Is there scientific evidence?


    Eating disorders

  • Can temperature also be a parameter in relativity?

    I think that temperature also depend on relativity.Metric may be depend on space time as well as temperature.

    Kåre Olaussen · Norwegian University of Science and Technology

    Temperature is a property of systems in thermal equilibrium, hence naturally defined in the inertial frame of reference of the equilibrium system. However, it makes perfect sense to describe such equilibrium distributions from other inertial frames, as when the thermal distribution of the cosmological microwave background is described from the (instantaneous) inertial frame of the earth.

    The natural way to proceed is not to use temperature T as the variable, but its inverse \beta = 1/(k_B T), which in the original frame can be viewed as the 0th component of a 4-vector (with all other components zero). When viewed from other frames this is transformed to a general 4-vector \beta\mu, such that \beta\mu  \beta \mu  = 1/(kBT)2, with the Boltzmann weight factor exp(-H/k T)  changed to exp(-c\beta\mu P\mu ). This f.i. generalizes (relativistic) Maxwell distribution functions to Juttner distribution functions.

  • How can I maintian RFP fluorescence?

    Can RFP fluorescence still be kept after paraformaldehyde fixtation? I recently wanted to do a IF-ststainig, and as far as I know, GFP fluorescence can be well preserved after paraformaldehyde fixtation. However, I have no idea about RFP.

    Sven Reister · Heinrich-Heine-Universität Düsseldorf


    for me formalin worked to preserve GFP but the problem starts with permeabilsation of the cell. The detergents abolish my Fluorescence so I could only advice you to use anti RFP-Ab or analyse the samples without permeabilisation



  • Is operations management course to be delivered as operations research curriculum only...???

    Many business schools treat operations management subject equivalent to/to be dominated by operations research techniques. While it is imperative to know the techniques to solve the managerial issues, it is very important for operations management students to dwell more on the business perspectives. I strongly vouch the students from OM background should know more managerial issues to see the usage of the techniques in their professional life. Here, the derivation of algorithm is immaterial where as the appropriateness of the technique matters a lot. I welcome the view points from the academicians and practitioners to have a discussion on this.

    Abdalla Garguri · University of Toledo

    The difference between both terms is the purpose of the science or courses. OR aims to answer or provides the best solution as a pure solid science ,while MO works as bridge between OR and business.
    In other words, the MO has social constraints has to be considered when it deals with issues for providing the solution those constraints drive toward the possible solutions more than the optimal ones.

  • Wilson C Santos added an answer in Organ Bath:
    What are the most suitable ways to induce endothelial dysfunction in isolated rat aorta?

    When we isolate rat aorta and soaked in organ bath with Krebs solution, I have two question

    1. The best way to remove endothelium

    2. The best way to induced endothelial dysfunction (rather than High glucose, H2O2 )

    Best Regard

    Wilson C Santos · Universidade Federal Fluminense

    For endothelium denudation, I recommend you gently rub the organ with cotton strip. For reference, I attach a file and quote another one for you:

    Caricati-Neto, A., Pupo, A.S., Wanderley, A.G., Nuñez-Vergara, M., Koh, I.H., Jurkiewicz, N., Jurkiewicz, A., 1995. Role of the epithelium in the release of contractile agents from the rat vas deferens by clonidine. Annals of the New York Academy of Sciences 763, 463–469.

  • Andrej Gajic added an answer in Fossils:
    Is the attached image a tooth mark?

    I got this Megalodon tooth fossil. Size is approximately 15.5cm long. I found unusual marks on the root. Something scratched marks on the same position and has the same form or on a regularly. It`s like a tooth mark which caused by sharp teeth. Is that true tooth mark?


  • Sven Reister added an answer in Transfection:
    How can I transfect a OCI-AML1 cell line?

    Has anybody successfully transfected OCI-AML1 cells. Is it possible to use any turbofect protocol to do so? The cell line is a suspension of the acute myeloid leukaemia. 

    thank you for your help.

    Sven Reister · Heinrich-Heine-Universität Düsseldorf

    I gained the experience that transducing with lentiviral particles is probably the best option for noumerous leukemic cell lines. Amxa workes fine to but for me it was rather a tool for transient expression because a lot of cells die due to the nukleofection

  • Does Collective Intelligence Exist?

    Simply put: I'm interested in how groups 'think,' 'learn,' 'perform,' and in turn; how this relates back to the individual.

    In particular, I am currently undertaking a Ph.D. on the topic of 'Collective Intelligence' under the supervision of Prof. John Hattie

    I am fascinated by the idea of expanding the typically individualistic notion of 'Intelligence' and 'Intelligence Testing' and applying these psychological subdisciplines to 'groups' of two or more people.

    For example, is there such as thing as a 'Collective Intelligence Factor' that distinctively represents the intelligence of groups (e.g. two or more people) and if so does this 'c-Factor' set the group apart from the intelligence of its individual members?

    In other words: is the Collective Intelligence of groups greater than the sum intelligence of its individual members?

    How can this collective intelligence be measured?

    Does 'group learning' translate to 'group intelligence'?

    Can we use existing psychometric tests (e.g. IQ tests) to measure and predict cognitive differences in groups?

    What makes one group more intelligent than another?

    Do groups made up of highly intelligent members demonstrate higher 'collective intelligence' and outperform groups made up of low or moderate intelligence members?

    If you have any links, papers, conferences, or general thoughts that would help me explore these ideas; i'd love to hear from you.

    Art Akopyn · The University of Western Ontario

    Whether Jews are in the aggregate more intelligent is for each to decide. Given what has been said by participants about peculiarities of human cultures, an attempt to maximize collective IQ is to structure the social group in a way that incentivizes reinforcement of the group.  A somewhat analogous process can be observed in the matters of gender equality - - women remain underprivileged to men so that men who reinforce the foundation of a social group are rewarded by it and acquire a value advantage as far as natural selection goes.

  • Daryn Dyer added an answer in National Culture:
    Does a tribe or national culture influence a company in deciding exporting and importing product?

    Our business management program is researching in cross culture decision making related with exporting and importing product around Asia,west europe,eastern europe,arab,africa and australia.

    We want to extends and apply hoefstede theory and eager to have international collaboration with other researcher around the world ask i stated above. As a started i need your opinion on this question  and possible joint research with our team.For pre-elemenary research power distance index cover most area of South East Asia and tendency of long term to short term as the influence of information and communication technology through mobile and social media.

    What do you think on tribe and nation culture that influence a company in a country decision to export and import product

    Daryn Dyer · York University

    Yes, understanding the national culture of the  people you do business with is critical. From Religion, traditions, business law, buying patterns to work practices, they can make the difference between success and failure:

    Earley, P. C., & Mosakowski, E. (2004). Cultural intelligence. Harvard business review, 82(10), 139-146.

  • What are applications of convex sets and the notion of convexity in mathematics and science?

    In a Euclidean space, an object S is convex, provided the line segment connecting each pair of points in S is also within S. Examples of convex objects in the attached image include convex polyhedra and tilings containing convex polygons.  Can other tilings containing convex shapes be found?

    Solid cubes (not hollow cubes or cubes with dents in them) are also examples of convex objects.   However, crescent shapes (a partial point-filled circular disk) are non-convex .   To test the non-convexity of a crescent, select a pair of points along the inner edge of a crescent and draw a line segment between the selected points.   Except for the end points, the remaining points in the line segment will not be within the crescent.  Except for the 3rd and 5th cubes, the cubes in the attached images are convex objects (all points bounded by walls of each cube are contained in the cube).


    From left-to-right, the cresent shapes are shown in the attached image are non-convex: Nakhchivan, Azerbaijan dome, Taj Mahal, flags of Algeria, Tunisia, Turkey and Turkmenistan. For more examples of crescent objects, see


    Can you identify other crescent shapes in art or in architecture that are non-convex?  Going further, can you identify other non-convex objects in art or in architecture?

    The notion of convexity leads to many practical applications such as optimization


    image processing


    and antismatroids, useful in discrete event simulation, AI planning, and feasible states of learners:
    In science, convex sets provide a basis solving optimization and duality problems, e.g.,
    Convex sets also appear in solving force closure in robotic grasping, e.g.,


    Recent work has been done on decomposing 2D and 3D models into their approximate convex components. See, for example, the attached decompositions from page 6 in
    J.-M. Lien, Approximate convex decomposition and its applications, Ph.D. thesis, Texas A&M University, 2006:


    There are many other applications of the notion of convexity in Science. Can you suggest any?

    Dr Bhavanari Satyanarayana · Acharya Nagarjuna University



  • Jerry Rhee added an answer in Grounded Theory:
    What is the best way to operationalize grounded theory?

    Since many conceptual thoughts are embedded in memos ( which -according to Charmaz- remain private and unshared), I wonder how to best operationalize the steps taken before the Integration of the abstract analyses in the grounded theory?

    Hi Martina,

    Another way to think of it is to see the thinking process as consisting of two steps in series; a System 1 and System 2.  The first part relies on intuition, the second on analysis/recursion. 

    Basically, when you approach a problem, you are trying to recognize and calculate.  If you find yourself in a stupor, you have to do more studying, more immersing.  You are trying to find some general structure to your problem, some framework that has been suggested in the past, an analogical structure.  If it's an entirely new pattern, then the problem may be beyond you.

    Once you recognize the framework, FIT IT INTO ABDUCTION.  That is, fill out what C (observation, explanandum, vision, etc) and A (mechanism, explanans, argumentative finesse, etc) are.  Then see if that framework can be used to predict something, no matter how small.  Once this is satisfied, then you might have the correct starting point.  You can see how this method depends on prior knowledge of heuristics.  That should give you a start.