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  • Interested to know about biofilm, isolation and identification of different spp.
    Food microbiology
  • Zeba Naqvi asked a question in Books:
    Book on microresonators

    I am looking for a book on theory of microresonators, telling everything about their modes families, their origin and all kinds of dispersion esp geometric dispersion. Something like Oraevsky's paper. A book dedicated to only microspheres will also help. Any suggestions? Thanks

  • Pierre Saouter added an answer in Sun:
    What force accelerates the cosmic rays from outer space to earths atomsphere? Do cosmic ray enter to sun?

    I am quite unsure of it.

    Pierre Saouter · University of Geneva

    Oh yes, Keran, you are right. Without the GZK effect, then even much higher energies could be achieved considering non-linear diffusive shock acceleration from a purely mathematical point of view. But to my knowledge, considering supernova as the accelerator site, then only energies of 10^15eV can be achieved (for protons of course since for heavier nuclei the threshold scales with the absolute electric charge Z), due, in part to the scale of the magnetic fields expected to be found in SN. For the very highest energies, we would still need to switch to other astrophysical objects (AGN perhaps...). 

    But you are perfectly right, my explanation was not as accurate as it should have been. 

    I guess we got a bit away from the original question but 

  • In which theory does computer assisted vocabulary learning fall into best?
    I have been conducting a study and would like to base it on a sound theory.Constructivist theory seems to fit to CALL applications best but I need to hear different views from the researhers here.
    John Franklin Wilhite · University of Tennessee

    I strongly agree with Antonio's viewpoint.  We are overwhelmed with approaches, models, methods, techniques.  Virginia's info is pertinent and should also be considered.

  • Jerry Rhee added an answer in Combinatorics:
    What is your favourite combinatorial object, or mathematical object you find the most fascinating?
    I always am curious of what types of combinatorial or mathematical objects (in general) interest other researchers. For myself I have a pretty keen interest in types of restricted weak integer compositions (weak implies 0 is applied in integer sequence whereas the lack of this description means you can't use 0 in integer sequences, and restricted means finding subsets of these objects).

    What combinatorial or mathematical object (preferably more elusive ones) fascinate you the most, or are your favourite

    Not sure if the following qualifies but this phi spiral?

  • Ljubomir Jacić added an answer in NATO:
    A referendum on full Scotland's independence is in progress. How will the results of this referendum affect the European Union, NATO ...?

    Scotland's independence could bring some reflections to some European regions such as Catalonia, South Tyrol, Flanders, the Basque Country. Even some ideas of ​​new state of Kurdistan can be dangerous, especially for Turkey who would like to become a member of the European Union. What are your concerns about, if any?

    Ljubomir Jacić · Technical College Požarevac

    The 'NO' result in Scotland mostly resulted from fear of the consequences of secession, although the knock-on effect will be considerable for Catalonia, defense analyst Dr. Binoy Kampmark told!

  • M. A. Zaky added an answer in Finite Difference:
    Whats the best way to solve the NSE well posedness problem?

    FEM or finite difference ?  Thanks all, Si

    M. A. Zaky · Beni Suef University

    If you are solving the Navier-Stokes equation with the periodic boundary conditions I would recommend you to use the spectral method, spectral methods are the best.

  • Why is the use of certain theories in management and business research in decline?

    There was a time when transaction cost economics, contingency theory, information theory were popular theories in management and business research. Nowadays, these theories seem to be regarded as old fashioned and a thing of the past. What are the reason in your expert opinion?

    Beata Stępień · Poznan University of Economics

    Dear All, 

    I do not regard TCE or CT as old fashioned or outdated, we simply build upon this and while doing so, we refer to other, newer advances in theory. TCE is economic theory, so its grounds, assumptions and methods is different from what is done in business and management. The latter is more applicable and - I would say... flexible, when it goes about the way it is developed. 

    Anyway, TCE and CT is still alive and well, and - in my opinion - it will survive long - as they are simply well grounded theories 

  • I need this book "Structural Inorganic Chemistry By A.F. Wells, 5th edition, Oxford University Press".

    If any one has this book ( soft copy) please share with me. it will be grateful to you. I searched in our library it is not available so, suggests me how to get online.

    John Franklin Wilhite · University of Tennessee

    You can probably get it from Amazon.  They have everything.

  • César A Terrazas added an answer in Flow Cytometry:
    Can anyone help with information on CCR7 vs CD45RA expression in CD4+ cells?

    Hello all,

    Would really appreciate some advice regarding CCR7 vs CD45RA expression. I am attaching the flow diagram that I am getting and we can't figure out what is going wrong. We are doing flow on fixed and frozen cells on a 8 color FACS Canto. Is the scatter supposed to look like this? 

  • John Franklin Wilhite added an answer in CAD:
    What is the potential of CAD/CAM technology to visual and performing arts practice design studio pedagogy in higher education?
    I am interested in your opinion on integrating CAD/CAM technology into studio based design teaching and learning practice in the arts.
    John Franklin Wilhite · University of Tennessee

    This has been on here a year with 169 views and not a single answer.  I wonder if it's because of the overuse of acronyms. People outside CAD/CAM won't know what they mean.  And the same letters can be used for multiple thinks. 

  • Rafael Morales added an answer in Chlorophyll:
    How do I remove chlorophyll from pandanus amaryllifolius leaf?

    What method can we use to remove chlorophyll without degrading the antioxidants in it?

    Rafael Morales · Universidad Nacional de Loja (UNL)

    puede utilizar clorolactofenol d´AMANN , en las proporciones siguientes: 2 de hiodrato de chloral 1 de phenol y 1 de ácido láctico

  • If any coordinates will do in General Relativity, is spatial curvature necessary? Is GR more complex than necessary, and is curvature verified?

    GR was introduced along with the principle that not only is no coordinate system preferred, but that any arbitrary coordinate system would do.  The complex mathematical machinery of covariance was introduced (including tensors) to express the laws of physics, any of the laws not just GR, in arbitrary coordinates.  This allows coordinate systems in which the distances vary with position and orientation, and in which the speed of light is non-isotropic (varies by direction), and such coordinates are routinely used in famous solutions such as Schwarzschild.

    So, it is not just the curvature of Riemannian geometry that requires complexity, but most of it is required by independence from coordinates.  And if indeed physics is independent of coordinates, can coordinates be found for solving GR problems in which space (if not spacetime) is flat and therefore graspable to the ordinary intuition?

    For an introduction to analysis of orbits using only time dilation, not  spatial curvature, see paper linked below.  GR was derived from the equivalence principle on the assumption that curvature was the only way to explain equivalence, but this is an argument not a proof according to GR verification authority Cliff Will.  If another method is available, it becomes a weak argument.  Is there empirical proof of curvature?

    Charles Francis · Jesus College, Cambridge

    Klaus, I don't actually see the difference. Empirically we work out the laws of physics as for inertial observers, who are "master" so to speak, and we embody those results into gtr by way of the special principle. Then we use general covariance as the means by which we those laws are understood by all observers in all coordinate systems. 

  • Can we perform a prospective study with 2 unequal in number groups?

    how could it be randomly grouped for statistical analysis?

    Philip C. Haycock · University of Bristol

    What are your groups? Are you setting up a new study? 

  • Kouame Mathieu added an answer in Phytochemicals:
    For best yield, what is the best method for preparing an aqueous, methanolic and ethanolic fraction from the leaf?

    Phytochemical extraction yield.

    Kouame Mathieu · University "Félix Houphouët-Boigny"

    Thank you !

  • Given their apparent archival nature, might social networks like ResearchGate provide a strong and viable alternative to journal publications?
    John Franklin Wilhite · University of Tennessee

    Oops!  There's my answer.  Where's it been for the past hour?  "Hmm, since there's an hour between the first (original) post and the second one and since answers generally appear instantly, and, further, since RG is mentioned several times in the original missive, I deduce that the only logical explanation is that RG held it for perusal to ascertain that their good name is not sullied, hence causing a slight delay in the posting (not publishing) of the first answer."  "Jolly good, Sherlock.  I think you've solved another one."

  • James F Peters added an answer in Robotics:
    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 circular disk containing all points inside the 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?

    James F Peters · University of Manitoba

    Dear Ljubomir,

    Yes, convex sets are omni-present and very useful in quite a few applications such as those mentioned by @Costas and by you.   

  • Can I calculate the size of thermodynamic segment (Kuhn length) based on the chemical formula of the substance without a computer simulation?

    Kuhn length calculation

    Douglas R Tree · University of California, Santa Barbara

    I don't know of an easy way to obtain the Kuhn length of a polymer without a measurement or simulation. However, it might help to know better how to answer your question if you explain why you need one. Many polymers have similar persistence lengths (of a few angstroms to a few nm) and lists of properties for common polymer can be found in many textbooks (e.g. Polymer Chemistry by Hiemenz and Lodge). Furthermore, a precise value of the Kuhn length is often unimportant for many calculations of inorganic polymers and you can assume that it is close to that of polyethlyene or polystyrene (lp ~ 6 ang).

    Finally, note that I have been sloppy with terminology, and you should carefully examine the definition of the statistical segment length/Kuhn length/persistence length you are interested in, if the exact value is important to you. The literature is rife with confusing terminology surrounding these lengths.

  • How can minority groups protect their culture and identity in the face of increasing globalisation?

    In a world characterised by increasing integration on economic, political and institutional levels, the notions of sovereignty and independence are becoming somewhat vagues and a number of social entities such as ethnic groups which exist within wider societies are perceiving such integration - which is partly due to globalisation - as a threat to their culture and identity. How can such social groups protect their culture in this context?

    Ljubomir Jacić · Technical College Požarevac

    "Efforts to protect local culture from the homogenizing effects of globalization are often intertwined with other, sometimes questionable, motives, including economic protectionism and the political suppression of ideas. Because the topic of culture can, almost by definition, encompass almost every human endeavour, it is often difficult to draw lines around what are legitimate cultural activities, worthy of special protective measures." Fine research from Levine Institute: Culture and Globalization!

    The role of media in the era of Globalisation should not be neglected, regarding the preservation of language and culture of minorities! Minority Languages and Cultures in the Face of Globalisation treats this issue-second link!

  • Do you think that publishing policies should be reconsidered again?

    from scratch data to publication in ISI journals with high impact factor is possible if you can pay money. even if you do not have data or idea, they will be offered for you. so what is the importance of publishing and what is that knowledge generated.

    please share your thoughts, perceptions into this vital topic.

    thanks in advance

    John Franklin Wilhite · University of Tennessee

    I think some people are more obsessed with journals, impact factors, citations, referees than with conducting their research.

  • How do I improve my R script for quality control?

    I have to make a script for quality control but the result not same as the journal. How do i improve my R script. This is the algorithm (file attached)

    Dasapta Erwin Irawan · University of Sydney

    Dear Cecilia,

    I've replied your email. Kindly check your mailbox.



  • What is the best internal control for Nicotiana tabacum?

    I'm doing RT-PCRs. Which gene is considered a good internal control for tobacco?

    Alexander I Tuzhikov · University of Miami Miller School of Medicine


    We used EF-1 elongation factor for different plants, including N. tabacum. Worked for us :) But there are others, please read this:


  • Marc-Antoine Langevin added an answer in Gamma Rays:
    What is the suggest setup and sample preparation (Nanoparticles) used for gamma fluorescence measurements?

    I am investigating some nanomaterials under Gamma Ray excitation. Initially I was expecting to see fluorescence from our materials under gamma excitation. But I didn't see anything however I did see with X-Ray though. We are using TE cooled PMT with background counting of 100 count per second. If there are at least more than 100 photons we should be able to pickup. The gamma source is Co-60 (0.5 mCi) with roughly 18940 KBq of activity. I believe that the activity of the order of 18940000 per sec, should be enough to see the fluorescence from the materials having yield even less than 1%. In this regard, I would like to get your suggestion and comments on it.

    Marc-Antoine Langevin · Laval University

    Hi, I suggest you to read the work of my colleagues: Lecavalier et al. Chem. Commun., 2013, 49, 11629-11631. DOI: 10.1039/C3CC46209A 

  • Ensieh Mosaddeghi added an answer in Stock Pricing:
    Can somebody suggest a good site for collecting stock price index data?

    I cannot find stock price index data for S&p 500 from 1995 to 2014 quarterly. I am using OLS model but I don't know which data I should use there are huge data types. For example FTSE100 has price index and also pound share prices which one I should use?

    Ensieh Mosaddeghi · University of Isfahan


    This website is very good for your purpose:

  • To what extent does an assessment system affect pupil / student performance?

    What evidence is there that an effective assessment system positively affects pupil performance? What does that effective assessment system look like and why?

    Mark E Gould · Education Queensland

    Ratna, I was pleased to see this article by Prof Masters. I have talked to him about it. ACER is a premier educational organisation, so to see him support this notion is wonderful. I began work on this issue in 2000 and consider it to be the single most important change in schooling for younger students to be put on the table for a long time, because it effects the perception of both teachers and students aboutwhat it means to be a successful learner.

  • Louis Brassard added an answer in Economy:
    Why did Marx think that rich countries would be more likely than poor countries to embrace communism?

    Marx's theory was that developed countries, with industrialization and capitalism, would have the greatest economic inequalities. What he failed to realize, though, was that these countries were generally the wealthiest and the freest, so the citizenry had a stake in the system as it was.

    Poorer countries embraced communism for a variety of reasons. They're poorer, as stated earlier. They're generally more corrupt, authoritarian, and nationalistic. They transitioned from agricultural economies to industrial economies quickly, but didn't have the institutional structures, civil society or wealth that western countries had and so couldn't endure the changes as well.

    Free market democracies are less likely to embrace communism, yes. You only have to look at countries in Asia--known as the Asian tigers--to see how quickly they lifted themselves out of poverty, and how democratic their governments became (comparatively, anyway), after opening themselves up to capitalism and free trade.

    I envision communism as a future possibily for humans to achieve truly a democratic form of living together.  Before we formed large societies with hierarchical structures we had small democratic societies, socieites without voting but without hiearchical structure and where what the small community was doing was decided by consensus.  This way of proceeding by consensus was not possible for larger societies.  Even the Greek city state democracies, the democracy were only a consensus among a small group of the society.  Wit the evolution of future social networks where collaboration of large group of people will become possible without a power hiearchy, these collaborative technologies will be applied to the level of the control of the whole society and we will get rid of these social hiearchies and will learn to coordinate our living together with consensual approaches involving billion of people and then communism, a society by the people for the peoples without artificial hiearchies will be achieve.  Marx did not have these future social network collaborative technologies that will allow us to achieve communism, a society moving towards the common good.

  • Does Ackermann function belong to Mu-recursive function?

    Some books say that a function can be Turing-computed if and only if it is a Mu-recursive function [1] . So Ackermann function should be Mu-recursive,Here,Mu-recursive is defined by primary recursive functions by composition or recursion schemes.

    Meanwhile, it is proved that Ackermann function is not primary recursive function, so it should not be Mu-recursive, which is contradictive to the above proposition.

    Then, does Ackermann function belong to Mu-recursive function after all?


    [1]Thomas A Sudkamp.Languages and Machine:An Introduction to the Theory of Computer Science,Third Edition, Pearson Education, Inc.,2006,pp.415-416.

    Yinsheng Zhang · Institute of Scientific and Technical Information of China

    @ Peter T Breuer

    You are close to Turing ,from Birmingha to Manchesterm is not so far,Ha ha.

  • Jonas Boateng added an answer in Gene Synthesis:
    According to you which one of the gene synthesis company is the best?

    See above

    Jonas Boateng · Microarrays

    I think Eurofins Genomics has a very good gene synthesis division. It depends on your preference. If you don't care much about turn around time or cost and want the cream of the crop then DNA2.0 is probably the Cadillac of Gene Synthesis. However, if you want quick TAT with moderate gene complexity and size then I strongly encourage you to try Eurofins Genomics. If you are a big pharma company looking for high throughput then GeneScript is probably your bet. Me personally I prefer Eurofins Genomics having worked there for close to 2 years I witnessed first hand the care and quality checks they put into place to ensure that the genes shipped are exactly what the customer paid for.