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
  • Keiko Tanaka added an answer in Mass Extinctions:
    What caused sub-aerial and oceanic Large Igneous Provinces (LIPs) during Cretaceous period?

    How episodes of Large Igneous Province (LIPs) could be confidently linked to the occurrence of Oceanic Anoxic events, biological consequences like mass extinction or oceanic Metal anomalies? Is all this purely hypothetical or based on sound scientific evidence?

    Keiko Tanaka · Independents

    About climate change at the KT boundary, I have discovered that important from my evolutionary theory. Continent variation trend of geological time, they will be considered to have shown with climate change the relationship, such as the very tight gear. I found that the quadrupole structure of the earth's magnetic field at the KT boundary is inferred. Continent variation trend and climate change and biological evolution of the Earth, I am learning the theory that these are very disciplined. 

  • Morton E. O'Kelly added an answer in Fixatives:
    Any one know the formal name for this approach?

    We are considering a multi-dimensional optimization problem. We adjust one dimension of the variable, with the other dimensions fixed; and then adjust the other dimension, with the other dimensions fixed. So on and so forth. What is the formal name for this method? Is "successive approximation"? any references? Thank you very much!

    Morton E. O'Kelly · The Ohio State University

    You did not mention if this is a nice (say convex ?) function or some function with a lot of local minima. How many dimensions do you have? It is a good approach if the conditions are well-suited .... fix x, vary y, fix y, vary x, etc. Very like say Fiacco and McCormick.

  • Paresh N Patel asked a question in Journalism:
    Can anyone suggest the journal, where I can publish the molecules with XRD and complete spectral data ???

    All molecules reporting first time....

  • Christa Utami added an answer in Stomata:
    Why do stomata close when excess water? How the mechanism?

    I means when water flooding. Thank you

    Christa Utami · Brawijaya University

    thank you sir

  • Rafael Morales Gamboa added an answer in Virtual Learning Environments:
    Are MOOCs a learning method?

    Several times I have found some colleague referring MOOC as learning methods (may be complex, but methods).

    Could they be considered as methods? Or more correctly, they are a class of virtual learning environments, where specific characteristics, like some kind of openness, and a great quantity of students (and, possibly, teachers and tutors), define process and relations among them, which include, specific for MOOC, methods

    Rafael Morales Gamboa · University of Guadalajara

    And students can have independent learning methods, so they are not "being received" by them from teachers.

  • Azzam K Almosallami added an answer in De-Broglie Bohm Theory:
    How do you see the non-locality of the wave-function and why it can't be used for the faster than light signaling?

    The wave-function describes a form of quantum energy called the quantum potential which propagates throughout space. Disturbing the quantum potential in one location instantly modifies it throughout the whole space. How you see this aspect related to the velocity of light?

    Azzam K Almosallami

    Dear Sofia D. Wechsler,  

    Rita De Vuyst is right. In fact according to SRT it is impossible to see faster than light because Einstein proposed in his interpretation to the Lorentz transformations the two observers on the ground and on the moving train must agree at the location of the moving train on the ground by proposing objectivity as in classical physics. By the reciprocity principle the length of the moving must be contracted in the direction of the velocity and the length on the ground must be contracted. When the train stops on Paris, then it stops in Paris for the both the two observers it is right! But before the train stops on Paris -during the motion- how can we know it is now on Paris for the both two observers? Einstein proposed that according to objectivity on the classical physics and according to that he kept on the continuity in classical physics. According to that, he killed the wave-particle duality and Heisenberg uncertainty principle in the Lorentz transformations. If that is not true, why some theories propose a violation of Lorentz invariance as in case Cherenkov radiation, and other theories propose a violation of Lorentz symmetry. Is Lorentz symmetry conserved in all ranges of velocities?

  • Brian Phiri Kampanje added an answer in Corporate Governance:
    Does anyone know any corporate governance model or framework for small and medium business?

    I´m looking for any corporate governance model of framework for small and medium business, specially in USA or Europe. Any article in this subject? Thanks a lot.

    Brian Phiri Kampanje · Blantyre International University

    The term SMEs is usually blur. SMEs very often means entities whose financial instruments (both equity and debt) are not traded on the public markets and do not hold funds on behalf of the public in a fiduciary capacity - financial institutions such as banks, insurers, discount houses, leasing houses etc. In other words their activities affect less market participant and truly investors and depositors. (public accountability).

    Classification of SMEs can also depend on turnover, number of employees or balance sheet size. Regarding the corporate governance, the classification regarding public accountability seems to be more plausible than size based on turnover, number of employees etc. It can safely be concluded that corporate governance for SMEs are there to guide directors to adopt best practices and not necessarily to reduce agency cost.

  • Merilee Karr added an answer in History of Medicine:
    Can anyone suggest archives on the west coast of America on native american medicine 1800-1900?

    I am currently in Washington (will be heading to New York, Boston and Harvard as well as Philidelphia while I am here) I am already looking into the Library of Congress, Smithsonian (Anthro & NMAI archives), American Philosophical Society, Penn State University Library and Harvard University Libraries.

    I have been told that collections in New York have been moved to Boston, and also that there are good archives in Boston anyway that I should look into.

    I am working on my PhD that is focusing on the history of medicine (meaning both the material culture and remedies and the ceremonial practices that relate to healing) of Native American communities, primarily I am focusing on Mi'kmaq communities outside of Halifax Nova Soctia in the mid 19th Century. I am interested in medical approaches (outlined above) generally but mainly in attitudes of Mi'kmaq peoples and healers toward Euro-Canadian medicine and vice-versa.

    If anyone is able to provide me with any helpful advice on archives that I may not have considered/know about then please contact me

    All the best

    Farrah

    Merilee Karr · Oregon Health and Science University

    Hi Farrah,

    I received a reply from the Oregon Historical Society, suggesting you contact the 

    Tamastslikt Cultural Center which is in Pendleton, Oregon, 

    and the OHSU (Oregon Health & Sciences University) Historical Collections & Archives. 

    Also, are you familiar with the 19th c herbalist Samuel Thomson? He was born in rural New Hampshire, his first teacher of plant medicines was a local medicine woman thought to be Native American, and some of the plant-based medicines he prescribed were already in use by Native Americans. Fascinating, forgotten character in American medical history. There's a good book about him, America's Botanico-Medical Movements: Vox Populi, by Alex Berman and Michael A Flannery. Its publisher is obscure, Pharmaceutical Products Press, An Imprint of The Haworth Press, Inc. I'm sure it's findable online. 

    Good hunting.

    Merilee

  • Maher Souguir added an answer in Salt Stress:
    How to do statistical analysis SPSS ?

    Please i need help , i am working on salt stress and the effect of humic acid application  . i have 4 variety of plant and 4 traitement (0 g/l ,2g/l, 4 g/l and 6g/l). every traitement divded into : 3 groups . for exemple 0 g/l without humic acid application ; 0g/l with humic acid application H1 and 0 g/l with humic acid application H2. i need to know whish test should i make with spss to compare all these traitement and to show how significant the traitement with humic acid was to alleviate the salt stress in 0 ,2,4  and 6 concentration of salt ?

    Maher Souguir · High Agronomic Institute of Chott Mariem

    THANKS FOR YOUR REPONSES . i want to know how to compare all traitement (interactions between traitement) for exemple if traitement with humic acid H1 with application 2 g/l of salt was better than the traitement with humic acid H2 with application of 4 g/l of salt ? I KNOW HOW to compare traitement . for exemple traitement with humic acid H1 IS better than traitement H2. BUT I SHOULD KNOW in which concentration it is better ? in 0 or 2 or 4 or 6  of salt .

  • Julia B. Smith added an answer in Exploratory Factor Analysis:
    I have conducted an Exploratory factor analysis, my three extracted factors only explain 36% of variance ? Is this acceptable ?

    Hello, I have completed an Exploratory factor analysis and have chosen to extract three factors yet cumulatively they only explain 36.6% of the data, and I am concerned that is not credible ?

    Other factors (4,5,6)  individually contribute a maximum of 4% each if included. My field is the social sciences and I would like to know if this is acceptable (with sources if possible) or what to do really ? 

    Julia B. Smith · Oakland University

    Your field is social science but you haven't said what your instrument is trying to measure.  If you were measuring mathematical knowledge of geometric proof, I would expect a much higher explanatory power from a set of items.  If you were measuring an attitude (such as self-efficacy), 36% of the variability explained is pretty typical because there is just so much noise in the item response.  So, it depends.  You will not find this information reported as part of a factor analysis in most studies, but you can contact psychometricians to see what explanatory power that different surveys typically have.

  • Rob Koch added an answer in Teaching:
    I need an article for a response paper on: Differentiation in teaching for middle school students. Can you help?

    I need an article for a response paper on: Differentiation in teaching for middle school students. Can you help?

    Rob Koch · Northcentral University

    Is there a specific subject or context that you are writing about?

  • Matthew Hayes asked a question in Conversion:
    Who owns Bugaco.com?

    I have seen many useful tools for sequence format conversion, but I want to know who I should cite (and more importantly that the data I upload is in the hands of trustworthy folks).

  • Paresh N Patel added an answer in Aromaticity:
    Could an electrophile attack the meta position on the aromatic ring?

    NH2 group on aromatic ring is para and ortho oriented group. Could an electrophile attack the meta position on the aromati ring? and in which cases?

    no other substituents are on the aromatic ring

    Paresh N Patel · Indian Institute of Technology Madras

    Hi,

    As already answered by many friends, -NH2 is electron releasing group so by nature it will direct the incoming electrophile on ortho and para position. But as the most of the electrophilic substitution reactions are under acidic condition, so -NH2 get protonated as -NH3+ and become electron withdrawing group and gives the mixture of products (o, m ,p).

    I think its better to start your reaction with nitro (-NO2) derivative and after your desired substitution you can reduce it to amine (-NH2), to get only meta product, however its depend which kind of electrophile you are want to put. And also its required quite high reaction condition as already one electrophile is there. 

    Please follow below link to get more clear idea..........

    https://books.google.co.in/books/about/Organic_Reaction_Mechanisms.html?id=KHIvAQAAIAAJ

  • Donald Newgreen added an answer in Extracellular Matrix:
    In brain tissue, what is the best extracellular matrix marker with a good antibody in the market?

    We are currently try to label our protein of interest in ECM of brain tissue, so we need a good ECM protein to co-label against. Based on your experience in this field, what is the best marker for ECM that have a good antibody in the market? Please provide me all the information of the protein and its antibody.

    Thank you so much for your help in this.

    Baher 

    Donald Newgreen · Murdoch Childrens Research Institute

    As Dr Yoshida stated the ECM of the CNS is complex, but one antibody that should give a broad idea of ECM distribution is the CS-56 monoclonal that recognises chondroitin sulphate (CS) chains of proteoglycans (PGs), including CNS CSPGs. It is a mouse IgM and reacts with CS of all species, and unlike some other GAG antibodies, it reacts with native antigen ie. does not require enzyme treatment to create a neo-epitope. This antibody is widely available commercially.

  • AR Reddy added an answer in 5G:
    Is spiral antenna a candidate for 4G / 5G cellular communication systems?

    Since fabrication and miniaturization is easy, will it be beneficial to realize large number of array of spiral antennas ?

    AR Reddy · Madanapalle Institute of Technology & Science

    @Mike: You may have also heard this called "virtual beam forming".

    Is it implemented in the handset ? If yes, can you provide the details ?

    AR Reddy

  • Andrey Luchnik added an answer in High Throughput Screening:
    How do I perform an in vitro synthetic lethality screening for cancer cells?

     I would like to perform the in vitro synthetic lethality screen in cancer cells to identify the synthetic lethal pair. Is there any HTS method for identification of  SL pair? and also any method to determine the anticancer compound  that inhibiting the codependent gene or protein of  SL pair?

    Andrey Luchnik · Russian Academy of Sciences

    Karen, you write: "Na+/K+-pump, having the highest metabolic energy (ATP) utilizing mechanism". Is not it? The highest metabolic energy is NTP joining to growing chain of nucleic acid (DNA or RNA) generating pirophosphate! 

    However Na+/K+-pump participates in this process (only) sometimes in nerve cells generating short-term memory RNA (energy consuming). 

    Please read the discussion: "Is neural plasticity a consequence of genomic flexibility?"  https://www.researchgate.net/post/Is_neural_plasticity_a_consequence_of_genomic_flexibility?_tpcectx=profile_highlights 

    Regards.

  • Edward Thomas White added an answer in Chemical Engineering:
    Anyone familiar with the solubility measurement of metastable form?

    Hi:

    I am working on the material that exist as anhydrate and monohydrate forms, and I want to measure the solubility data of anhydrate in a low temperature, but in that temperature the anhydrate is the metastable one and can transform to the monohydrate. So how could I measure the solubility data of the metastable form?

    Edward Thomas White · University of Queensland 

    If you ensure there is NONE of the stable phase present in the vessel, you may be able to get a solubility measurement or two in the unstable region, because there can be a meta-stable region where there will be minimal nucleation of the stable phase. Without nucleation, stable crystals cannot form..  This may best be done by starting in a region where the anhydrous phase is the stable one (and holding it there for some time to ensure conversion of  all the monohydrate to anhydrous.Then move it into the unstable region (by changing temperature or gently adding a reagent?) and hold it there till it equilibrates with the solution. At the end check the solid (XRD, water content?) to show that there is none of the stable phase present.

  • Manuel Esperón-Rodríguez added an answer in Drought Stress:
    Which one is more important for constructing water conserving plants?

    Most of the water loss from the plants control by the function and the number of the stomata. Which one (stomatal aperture or stomatal density) you think is more important for water use efficiency and also drought tolerance by plants?

    Manuel Esperón-Rodríguez · Universidad Nacional Autónoma de México

    Dear Sasan Aliniaeifard,

    I have done some work assessing drought tolerance, and I've always used stomata aperture. Although stomatal density can be influenced as well by the environment, I believe it is easier to measure stomata aperture, and for me it was useful because I could determine optimal responses and gSMAX.

  • Stavros Nikou asked a question in UNESCO:
    UNESCO ICT Competency Framework for teachers?

    Any known implementations?

  • Aljoriz Dublin added an answer in Qualitative Research:
    How can I do qualitative research interviews by e-mail?

    I plan to interview a couple of experts in a field and find out which skills they consider most crucial for success in this field and how these skills can best be trained. Instead of speaking with these experts and then transcribing our conversations I consider doing the interviews in the frame of e-mail exchanges. Now I am wondering how such e-mail interviews can be done in a methodologically correct fashion. So I am grateful for direct recommendations or hints at good sources..! Cheers

    Aljoriz Dublin · University of the Visayas

    Email interview may be appropriate in disability centric studies where oral communication may deem to be limiting otherwise email interview alone is not sufficient, I suggestion combining either a telephone follow up or a personal visit to have a clarification on certain matters that the interviewee pointed out.

  • Tausif Alam added an answer in C57Bl/6:
    Can anybody help me in maintaining Euglycemia during Hyperinsulinemic-Euglycemic Clamp in C57Bl/6 Mice?

    Dear Sir/Ma'm

    We are trying to establish hyperinsulinemic-Euglycemic clamp technique in C57Bl/6 Mice. We fasted the mice for 6 hours.  We are using 3-H3 Glucose for tracer, 16mIU insulin for priming and then 4mIU for continuous delivery for 2 hours (As suggested by Vanderbilt).  We are using 20% glucose for Euglycemia. Can anybody help me in maintaining Euglycemia?

    What concentration/Rate of glucose/Min should I infuse to maintain Euglycemia?

    Thanks in advance

    Tausif Alam · University of Wisconsin–Madison

    Please do a literature search, this is an old technique and you should be able to find a great deal of information. Glucose infusion rate is often varied to maintain euglycemia.

    Your dose of insulin, as written, makes no sense.

    Assuming that it is per kg per min, the glucose infusion rate may range around 30-40mg/kg/min... just a guess from recollection of work done decades ago (animals were unrestrained to reduce stress, arterial blood was drawn for sampling and glucose/insulin was infused through venous route- tubes were placed several days prior to the test).

  • Brian Phiri Kampanje added an answer in Corporate Governance:
    What is your idea about the relationship between ownership concentration and the optimal level of risky investments (eg R&D)?

    A high ownership concentration does not necessarily produce an over-investment. In fact, if prevails the risk aversion of major shareholders who own undiversified portfolios, there may be the phenomenon of underinvestment. What do you think?

    Thanks in advance for your helpful suggestions and comments.

    Brian Phiri Kampanje · Blantyre International University

    Investment in R&D pretty well depends on the type of industry. High-tech and fashion businesses are compelled to invested in R&D regardless of ownership concentration probably as means to survive and grow in turbulent and very often unpredictable markets.

  • Timothy A Brusseau added an answer in Physical Activity Assessment:
    What is the best questionnaire to measure physical activity?

    I use IPAQ, but i'm not content, because the questions refers to the last week. Does anyone knows or use another questionnaire? Does anyone has a reference comparing the IPAQ with another questionnaire?

    Timothy A Brusseau · University of Utah

    I have also seen the PAQ-C and PAQ-A utlized.

  • Naghmi Shireen asked a question in NVivo:
    What would be the best tool for quantitative analysis of video data?

    I am extracting data based on analyzing 2- to 3-hours long videos. I am looking for some software that can help speed up this encoding process. The resultant data includes snapshots, descriptive and qualitative markers. Anyone with previous experience with video analysis, please help! Tool's ability to generate graphics will be a big plus. (NOTE: have already tried NVivo - does not work well for my purposes)

  • Carlos José La Rosa added an answer in Water:
    Is it logical to perform extreme value analysis on a deterministic phenomenon?

    I am going to use evaluate extreme analysis to compute extreme water level of the Caspian Sea from long term mean monthly water level records. But as the Volga river is the main inflow to the lake (80% of total inflow) and its discharge is regulated at the upstream dams, I think we can not consider it as an stochastic parameter. So I wanted to know whether it is correct to use extreme value analysis on this type of data or not?

    Carlos José La Rosa · University of the Andes (Venezuela)

    Dear friend. All process that are represented by an mathematic equation, are deterministics, course, included stochastics process. The theory of extreme value, permits us to make predictions in cases where are involucred natural and/or human extreme phenomenon able to be predictable. The suggest of Mr.Martijn J. Booij it is very idoneous, to give it your study more fundamentation..
    Regards

  • Sethanne Howard added an answer in Galaxy:
    How can we show the mass of the galaxy in terms of the observed velocity?

    A disk-shaped rotating galaxy is seen edge on. By Doppler-shift spectroscopic measurements we can determine the speed V with which the stars near the edge of the galaxy rotate about its center.How can show that the mass (M) of the galaxy is in terms of the observed velocity?

    Sethanne Howard · United States Naval Observatory

    Title: The Rotation and Mass of NGC 2146.
    Authors: Burbidge, E. M., Burbidge, G. R., & Prendergast, K. H.
    Journal: Astrophysical Journal, vol. 130, p.739  1959

    gives the full equations for determining the mass of a spiral galaxy from its spectral lines.  Measure velocity versus radius aong the spectral line to build up a rotation curve.    You can fit models to the rotation curve, or you can solve the messy equations.  This is the complicated version of what Greg just said above.

    But by and large, it is a difficult problem because galaxies are so different from each other.   Basically for spiral galaxies you can use 10^11 solar masses.  Ellipticals can be more massive. 

  • Kaio Alexandre Marques asked a question in Flow Control:
    What is a good Mass flow controller for a CVD system?

    I am setting up a CVD system, could you help to find a good Mass flow controller and a gas-mixing unit? 

  • Russell Linscott added an answer in Immunohistochemical Staining:
    Does anyone know an Ab for p-JNK that works on mouse paraffin sections for IHC?

    Many thanks in advance

    Russell Linscott · Independent Researcher

    If you need more possible sources, we list several. Just search here: http://www.linscottsdirectory.com/search/antibodies for phospho-JNK, and select Mouse and IHC from the filters. Follow the "more info" links for suppliers' datasheets. None of them seem to specify suitability for paraffin sections, but it might be worth contacting their tech support to see.