Q&A

ResearchGate Q&A lets scientists and researchers exchange questions and answers relating to their research expertise, including areas such as techniques and methodologies.

Browse by research topic to find out what others in your field are discussing.

Browse Topics

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
  • Mireille Kameni added an answer in Nymphaea
    Is anyone working on Nymphaea lotus or other Water Lily species?
    I am working on the androgenic and aphrodisiac properties of the aqueous extract of the flowers of N. lotus, but I know that this plant is a widely spread plant, so I don't understand why no one has conducted studies (except for anti-bacterial properties) on this plant. Maybe I'm not good at searching for actualities on the web.
    Mireille Kameni · University of Yaounde I
    Thank you hans
  • Sribas Goswami asked a question in Applied Ethics
    Should it be ethical to use animals for sports and entertainment?
    Animal rights, Legal aspects. What do you think?
  • Herbert F Jelinek asked a question in uploading files to ResearchGate
    uploading files o ResearchGate
    a couple of weeks ago I started gettig nthis message that "an error occurred while parsing for uploading the file" I can't find an yexplanation for this and therefore can't upload any papers if requested or not. Can anybody hlep please? Thx
  • Louis Pagliaro added an answer in Psychosis
    Why might cannabis use be related to symptoms of psychosis?
    A question on psychosis.
    Louis Pagliaro · University of Alberta
    Dear Helena, Congratulations on the successful completion of your program and welcome to the "field"! I enjoyed all of the responses to your original question -- responses that I found thoughtful and credible . . . For a detailed analysis of your original question and to assist with your current endeavors, I would suggest that you look at one of my recent texts, Substance Use Among Children and Adolescents: Developmental, Pharmacological, and Clinical Considerations (John Wiley & Sons, 2012) -- it is available online for perusal. I trust that you will find this text to be both interesting and informative. Sincerely, Lou
  • Which text book do you prefer?
    I'm writing a book on STATICS for undergraduate students and I'm wondering what is your opinion about the following cases. Thanks for your contribution. A) Less than 300 pages + solved and unsolved examples B) Less than 300 pages + only solved examples C) More than 300 pages + solved and unsolved examples D) More than 300 pages + only solved examples
  • Nick J Fox added an answer in Research Methods
    Should we draw a boundary for each subject in the domain of knowledge?
    Scope of subject, interdisciplinary value or any other dimensions on this matter?
    Nick Fox · The University of Sheffield
    Dear Sribas and others If you see a boundary, ask who has placed it there! Boundaries serve interests of power, as they define what is ‘known’ and what is outside of ‘knowledge’. Being able to define what is accepted as knowledge supplies authority and control. The significance of the boundary in relation to power was brilliantly set out in Derrida’s discussion of ‘the frame’ in his book ‘The Truth in Painting’. Nick
  • Terry B. Bollinger added an answer in Entanglement
    How does quantum entanglement survive transmission through a lens?
    Many EPR experiments use pairs of entangled photons. If entanglement is so fragile, how can entanglement survive transmission through the glass lenses so frequently used in EPR experiments? My concern? The standard explanation for the cause of refraction in glass is the delay caused by absorption/re-emission of the photon by many, many electrons. Absorption destroys the photon; emission creates a new photon. In EPR experiments, these destructive, jumpy interactions within a lens do not constitute a 'measurement' that disrupts entanglement, but this implies that entanglement can be temporarily stored by the wavefunction of an electron (or the atom or glass), which is then restored to a brand new photon. Is an electron's wavefunction complex enough to store entanglement? Is this process clearly explained in any literature?
    Terry Bollinger · MITRE
    This is an old question that already has several very good answers, so I only wanted to add a simple but handy rule: If the photon leaves the atoms undisturbed, that is, without any trace of its passage, then it will remain quantum and entangled.
  • Mireille Kameni added an answer in Biology
    In a MTT viability test, What is the concentration of plant extracts should be useful to use?
    I would like to study anti proliferative activity of plant extracts using the MTT test. And i wonder which concentration of plant extracts should I used. What parameters, should I take account to choose these concentrations. Thank you
    Mireille Kameni · University of Yaounde I
    If you have any ideas concerning the right concentrations to be use, may be you should make a screening test using differents concentrations from 1-10 microgram/mL of extract or from 10-100.
  • Can anyone suggest me how to study the variations in mirna expression profiles in cell lines upon various conditions?
    Our aim is identification of mirnas expressed in cancer cells upon stimulation with natural products. As I am concern Real-time PCR and microarray methods are commonly used for mirna expression studies. But I couldn't understand which method is superior for identification of variations in mirna expression profiles in cell lines upon various conditions. Pl suggest me, Can I get commercial kit for studying variations in mirnas expression profiles.
  • P-type or n-type semiconductor?
    Is there any specif method for the confirmation of a semiconductor to be p-type or n-type?
  • Beginners book for Pharmacophore based drug design ?
    Which book shall I begin Pharmacophore based drug design when my aim to know the definite workflow of Pharmacophore based drug design ?
  • How should I choose a particular gauge in first order perturbation in general relativity?
    In the case of general relativity the change in coordinate can give rise to fictitious perturbations, for which we can use gauge invariant variables or we can also choose a specific gauge. My question is how to decide which gauge is suitable for a particular problem?
    Rolando Deveras · Universidad de Carabobo, UC
    Following Dr. Eubanks, if one assume gravity as a gauge theory, there is a nice analogy with Yang-Mills theory about possible gauge fixations. For example, let $h_{\mu\nu}$ be the graviton field in a perturbative regime, then the "Coulomb" gauge must be $\partial_i h_{i\nu}=0$. Observe that this fixation is no more a general relativistic covariant constraint. So, in gravity a gauge fixation and covariance constraint go hand in hand.
  • Louis Pagliaro added an answer in Psychotherapy
    Does spirituality or religious beliefs help or hinder the therapeutic process for psychiatric disorders?
    Many individuals who present for treatment of a psychiatric disorder have strong and well-formed spiritual or religious beliefs. Can this characteristic be leveraged to help alleviate symptoms and behaviors, or does it act as a barrier by its rigidity and resistance to new or nonorthodox solutions?
    Louis Pagliaro · University of Alberta
    Dear Neil, Excellent question and likewise excellent responses . . . Many valid points have been made. As a clinical psychologist with over 30 years of experience, particularly with adult patients with concurrent disorders, I have found that I can often use the established and espoused spiritual or religious beliefs of my patients to their advantage. A common example, from my clinical practice experience, is use of their spiritual and religious beliefs to provide "hope" (true hope, not "false hope") --- which has been clearly empirically established to be associated with positive therapeutic outcomes (for a number of both mental and physical disorders). The bottom line, is to individualize our therapeutic approach, using whatever resources we have available to us in a humanistic manner (and with the application of the principles of "best practices" in mind), in order to do our best to help our patients. Sincerely, Lou
  • Ricardo Martinez asked a question in microRNA
    How does one go about comparing the trancriptome of humans and HIV viruses?
    I'm trying to find a 3'UTR target in HIV mRNAs with no homology in the transcriptome of Humans. #trying
  • H.G. Callaway added an answer in Critical Thinking
    Why do science students get taught so little about the scientific method
    Both at school and university in science the student is taught a lot about biology, physics or chemistry but very little about the different (good and bad) ways of doing science. Why is it so late in a person's scientific life are they told about things like inductive reasoning and the better ideas of Karl Popper (falsificationism) ? I found out about these things while reading "What is this thing called science" by Alan Chalmers.
    H.G. Callaway · Philadelphia
    Dear Foreman, It seems now that your interest is a bit different from that of your initial question--more a matter of Why aren't advanced students in the sciences methodologically sophisticated?, rather than, Why is methodology taught so late? These strike me as quite different questions. As for teaching facts, in science, this would seem to be unavoidable, if students are to make sense of the ways in which theory can encompass or conflict with those facts. So teaching of facts in the sciences must be accompanies by the teaching of theory in relation to relevant facts. It is by reference to theory that relevance is more fully brought out. Too, often, however, students just want to get by the exams. I have certainly heard this complaint about lack of methodological/scientific sophistication in advanced students. Here I sympathize. I have a little story of an encounter with an advanced student (of philosophy) in a European university setting. I showed the fellow a then recent book which I took to be highly relevant to his specific interests. (I was by far the more senior person in the encounter.) What the fellow did was to simply turn to the bibliography in the book, look through the listing of authors, and on that basis decided that the book didn't interest him. (It was typical that the book didn't have an index.) This frankly amazed me, since I was so accustomed to judging of the interest and relevancy of material on the basis of its subject-matter, instead of the author's referenced. But on reflection this made sense to me, since I saw a pattern in which the students simply studied the perspectives and references of their professors--who were going to be present at the oral exams in any case. This is, or can be, a version of rote learning. The typical result was a very deep knowledge of a fairly narrow slice of the field, and little interest in others writing and publishing on the same or closely related topics. (Very little of "compare and contrast.") I also recall situations in which different students in the same department (this was at another European university), each following a different professor in the same department, ended up not understanding each other, and unable to discuss their differences, because their professors where in a long-standing conflict of some sort or other--obscure to all except those directly involved. The students seemed to simply recapitulate the standing conflict, and yet this counted as education. If your professor approves your,o.k., otherwise not. Now, ask yourself why students would concern themselves with complicated questions of methodology in such circumstances. If the students already know the cast of their final exams, then they will likely listen, not at all, to any doubts or alternatives. The impulse of the professors to "reproduce" themselves via their students, and thus show their influence, is in standing tension or conflict with gaining a more encompassing view of the subject. I should say that I also encountered very considerable intellectual independence among students, who rarely asked for or needed any help within the confines of courses I taught --logic, say. But in a course with unusual or controversial content, I'd see the students of some sitting professor or other, who would come in as self-appointed critics and defenders of the established line. (This seemed crucial to the academic politics of their professors.) I can imagine that your professor wanted you to think through those 10 equations yourself --in relation to the rest. That's a good exercise, though challenging. Beyond that challenge would be to encompassing the divergence between differing text books and approaches. It is by challenging ourselves with differing and divergent approaches and views, theories and perspectives that our methodological scruples are best sharpened. "Compare and contrast." It may be, however, that this is not often the most direct career route. H.G. Callaway
  • Mustafa Said added an answer in Linear Algebra
    The recent trends in Linear algebra
    What is the current research interests in Linear Algebra? Can anyone mention specifically?
    Mustafa Said · University of California, Irvine
    There is a lot of new research that illustrates the interplay between linear algebra and analysis. In my dissertation, for example, we proved several results on an old problem in linear algebra and operator theory, are "almost commuting" matrices perturbations of commuting matrices? Once a space of matrices is equipped with a norm, then one can consider many interesting questions. In this direction, a good research paper to start with is R. Exel and Terry Loring's paper on "Almost Commuting Unitary Matrices." The paper is only 3 pages long and is suitable for students who have studied linear algebra and real/complex analysis.
  • qPCR: Standard deviation of reference sample?
    I've come across various methods to determine the summarised error in qPCR experiments that included all biological and technical replicates. Although I haven't had much trouble performing these calculations for the experimental samples, I've found it more difficult to calculate the standard deviation of the biological replicates of reference samples as these are often set at 100% or 1-fold. All to often have I seen results published that don't include the standard deviation of reference samples and comparative tests are subsequently performed between the experimental and reference dataset. This seems wrong. The SD of the technical replicates can be calculated for both experimental and reference samples, but does anybody know a good method to calculate the SD between biological replicates of the reference samples?
    Yogendra Rathore · University of Pennsylvania
    Can somebody explain this question with some example? I also have similar problem and want to process the data in right way. I can provide a simple example if anybody can help me in understanding the calculation. For Example, I have15 "test samples" and their 15 respective "control samples". For now just consider one set i.e. one "test sample" and one "control sample". I repeated it three times (both test and control) and I have three values for each. For example, for 'test sample" the values are 3,4,5 and for '"control sample" the values are 1,2,2. Now, the 'mean and the standard deviation' for "Test" and "control" are '4 and 1' and '1.67 and 0.58' respectively. Now, can anybody tell me how to normalize the "test sample" using this "control sample".
  • Stephen Warren added an answer in Water Quality
    Does anyone have articles or research papers on impact of river pollution on livelihood of fishermen
    I am interested in knowing is there any study going on river water pollution and its impact on livelihood of fisherman community
    Stephen Warren · Marlow
    Be careful with DO. Saturation is 14.63 mg/l at 0 deg, 10.13 at 15 deg and 7.62 at 30 deg. A low moving shallow river will reach 30 deg in summer and even at 80% saturation will barely reach 6 mg/l which is the limit for recommended in the EU. The Dniester near Odessa used to fall below 6 mg to 5 mg/l sometimes without any ill effects. The level was reduced by the bio-oxidation of organic matter (decaying leaves and soil run-off - NOT pollution). I do not wish to paint a too rosy picture of water quality but you need to understand water quality well to deduce things about the origin and effects of substances in water. I am neither a skeptic nor an environmentalist but a scientist who likes to get to the truth because truth is an attribute of reality and science has become so politicized that we have to be very careful before we accept others' conclusions.
  • Alex Gilgur added an answer in Linear Regression
    What is a good software for curve fitting?
    I am looking for a good software for fitting curves and would like to hear what software other people recommend. I want to be able to fit 4- and 5- parameter logistic curves and linear regression. Any suggestions?
    Alex Gilgur · Google Inc.
    Varun, i agree, but I wouldn't start with nls() as a familiarization tool. Go with lm() instead: the linearity is in parameters, not in independent variables, and it very nicely covers a huge landscape of regressions. The nls() is very powerful, but it requires that you provide it with initial values; it may fail to converge on the solution, it will mistake a non-normal distribution for an effect of nonlinearity, etc. It's much more complicated than lm() or even rq () of the quantreg package in R.
  • Jim Arnold added an answer in General Relativity
    Why is there so much fuss over the twin paradox in General Relativity?
    In the twin paradox, AA is the brother who stays on Earth and BB the traveler who is moving away from the earth, in the rocket. When BB returns, AA thinks that BB is the youngest because the speed of the rocket was almost c. However, BB believes that the Earth is who took away his brother from him and when they are reunited, notes that AA has not aged as much as he. Clearly, if there is no preferred reference frame, they cannot feel a difference in age.
    Jim Arnold · Penngrove U
    Chris, I think you meant to say "General, not Special"… There is no acceleration in SR.
  • Urban Design, Architecture, Planning and Landscape Architecture; Are these disciplines originated from the same knowledge base?
    Urban Design, Architecture, Planning and Landscape Architecture are acknowledged as independent disciplines (by now) that deal with designing spaces. In practice, each above discipline has strongly institutionalized professional demarcations. Yet, spatial design projects within urban environment done by Architects, Planners or Landscape Architects, are commonly labelled as 'Urban Design Projects'.
    Buddhi Guluwita · La Trobe University
    Thanks Claus. Your comment is a motivation for me to go on with my research.
  • If I am to promote RG in a research paper, what inputs should I include?
    Dear RG colleagues, kindly respond. Thank you.
    Alexandre Beluco · Universidade Federal do Rio Grande do Sul
    It's a great idea! You can count on me. I have some ideas for questions that would result in interesting articles related to the work of researchers.
  • Golam Kibria added an answer in Ecology
    What repercussions can global warming cause for the population?
    The increase in global average temperature modifies the atmosphere which in turn affects all biodiversity.
    Golam Kibria · RMIT University
    1. Human: Global warming will impact on all biodiversity including mammals (human). Human health will be affected since there will be proliferation of pests and pathogens in a warming world which will have several consequences, in particular cholera and malaria epidemics are projected to expand in some countries/locations, food poisoning might increase since higher temperatures generally favour the multiplication of harmful bacteria such as Salmonella. There will more environmental refuges due to increase in the frequency and intensity of disasters like cyclone, floods, droughts and storm surges. One of the most serious consequences will be (locations based) sea-level rise impact on assets and infrastructure, food and water (due to salinization) and human health. 2. Other biodiversity: Many species have already shifted their geographical ranges, generally poleward, towards higher elevations, or to deeper depths in marine environments to escape rising temperatures.
  • Michael S. Sacks added an answer in CFD Simulation
    How can non linear material elasticity such as animal and human tissue be defined from a multiple tested specimens?
    I need some advise for defining material elasticity that can be used for my modeling using biaxial and uniaxial tested specimens. Is it sufficient by using curve fitting method with any constitutive model from hyperelastic or viscoelastic material model? How can I define it with numbers of tested specimens if I have more than one data? Thanks.
    Michael Sacks · University of Texas at Austin
    Consistency and relative comparisons are very good basic tools, but one also needs to consider the question to be asked. For example, I often get questions like "what is Young's modulus for skin?" The problems with this question should be obvious to everyone reading this post, but think about it in terms of consistency and relative comparisons - both could be done but the answer - defining a Young's modulus for a non-LEHI material, is still wrong.
  • Nizamuddin Shaik added an answer in VLSI
    Is FINFET fabrication ready for production?
    See above
    Nizamuddin Shaik · Infotech Enterprises Limited
    Thank you, link is very useful
  • James F Peters added an answer in Geometry
    Are there mathematicians, scientists or philosophers whose work you view as influencing historical events in a minor or in a major significant way?
    Do you think that the interaction between such scholars has led to the success of their work in making an impact? Scholars such as Euclid (geometry), Newton (science), Plato (philosophy) have been very influential in shaping the way we see the world. For example, Euclid’s Elements written in Alexandria around 300 B.C. became a standard work in geometry. It is one of the most widely read, translated and commented on work in European history. It was translated into Arabic around 800 A.D., into Chinese in 17th century and into Sanskit in the 18th century. The first english version of Euclid’s Elements was Sir Henry Billingsley’s translation published in 1570. Euclidean geometry has been enormously influential in shaping our view of the world. For more about this, see http://www.hf.uio.no/ikos/english/research/projects/euclid/ Plato, 428-348 B.C., descendent from kings of Athens and Messenia, student of Socrates, teacher of Aristotle, founded the Academy of Athens, one of the institutions of higher learning in the Western world. He wrote about justice, beauty, equality, political philosophy, theology, cosmology, epistemology and the philosophy of language. For more about this, see http://www.biography.com/people/plato-9442588#awesm=~oBHUNDFF6ggpWQ A central notion in Plato’s philosophy is the theory of forms. The only true being is founded upon the forms, the eternal, unchangeable, perfect types, of which particular objects of sense are imperfect copies. This theory has been enormously influential in science and mathematics. For more about this, see http://www.ams.org/notices/201002/rtx100200239p.pdf Isaac Newton, 1643-1727, son of a farmer, Professor at Cambridge University, taught optics, introduced a theory of colours of light and theory of gravitation, published his Mathematical Principles of Natural Philosophy, 1687, introducing infinitesimal calculus, co-discovered (with Leibniz). During his study of optics, Newton investigated the refraction of light, demonstrating that the multi-coloured speturm produced by prism (see attached image) could be recomposed into white light by a lens and a second prism. He showed that colour is the result of objects interacting with already-coloured light rather than objects generating the colour themselves. He designed the first reflecting telescope, demonstrating his telescope to the Royal Society in 1671.
    James Peters · University of Manitoba
    Following up on what Kamal Bani-Hani has written, One of the major discoveries comes from James Watson and Francis Crick. In mid-March 1953, using experimental data collected by Rosalind Franklin and Maurice Wilkins, Watson and Crick deduced the double helix structure of DNA.Sir Lawrence Bragg, the director of the Cavendish Laboratory (where Watson and Crick worked), made the original announcement of the discovery at a Solvay conference on proteins in Belgium on April 8, 1953; it went unreported by the press. Watson and Crick submitted a paper to the scientific journal Nature, which was published on April 25, 1953. This has been described by some other biologists and Nobel laureates as the most important scientific discovery of the 20th century. For more about this, see http://en.wikipedia.org/wiki/James_Watson The attached image shows the DNA structure for four common deoxyribonucleotides are connected by phosphodiester bonds to form a single-strand.
  • Mireille Kameni added an answer in Neuroscience
    How to discuss results which are not statisically significant in a dissertation?
    Have a P value >0.05 for all my IHC, how can I discuss why this is a relevant result in the broad scheme of things? Thanks!
    Mireille Kameni · University of Yaounde I
    i already have such results which where higher but not significantly different so i have just used it as percentage, the results of control group were attributed the max i.e 100% and the other where determined following a simply mathematic rule : (C-T/C*100). So you can compare the evolution rate of a parameter with the control
  • What is your view of adding physical education mark to be included in the general hi school exam, transcript and certificate?
    Many schooling system do not give a credit to physical education marks and it is negligible to the hi school certificate. However, in some schooling system there are significant attributes to the physical education evaluation exams and it does affect the student total score.
    Louis Pagliaro · University of Alberta
    Dear Colleagues, As an educator and educational psychologist, I would certainly agree that it is logical and appropriate, as has been suggested, to give credit for successful completion of ALL required courses on high school transcripts -- including physical education. Perhaps, however, this credit would be best indicated by a mark of "pass/fail" versus an actual course grade --- which would then contribute to the student's high school GPA. The reason I suggest this approach is that "high school GPA" has proven to be a very reliable and valid predictor of post-secondary student academic success (at least for the first year) and adding the "grade" received in PE courses would decrease the predictive value of "high school GPA" in this context. Sincerely, Lou
  • Wesley Peres added an answer in Soft Computing
    Can anyone recommend good implementations in MATLAB of local search methods for continuous optimization?
    I already have the codes for CMA-ES, Nelder-Mead, Pattern Search.
    Wesley Peres · Federal University of Juiz de Fora
    Dear Sonia I have worked with Cuckoo-Search and Bat-Algorithm(BAT) and they have been providing interesting results. If you are interested, you can get further information through google or by getting in touch with me. Regards, Wesley
  • What is the best way to perform esophago-jejunostomy in a laparoscopic total gastrectomy?
    How do you make an purse-string suture for an anvil?
    Takehiro Hachisuka · Yokkaichi Municipal Hospital
    Dear Dr. Melani, Thank you for your answer. The technique you mentioned is used in Japan. Dr. Ohmori, Osaka Police Hospital, who is very famous for Single- Incison Lap Gastrectomy in my country, uses this method and presented in medical conferences here. TH