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

  • Narayanan Bhattathiri added an answer in Oncology:
    Clinical Phase II to Phase III failures in oncology?

    I am requesting the help of the RG community to provide me with recent (no older than 5 years) articles (from very high and only from very high ranked journals) clearly

    1) indicating how many and

    2) why

    so many positive Phase II clinical trials in oncology die during Phase III.

    I am quite new on RG ... but I already saw that "several" RG members are responding to questions like mine "why are you not making your biblio search by yourself ...".

    I did it but I am not convinced at all that I actually have the best articles in this field.

    Thank you for your time and attention.


    Narayanan Bhattathiri

    Dear Bobby

    Sorry for the mis-spelling. I think my mind intended Boss, which we use instead of Sir and gives a sort of elevated but closer relation ship!

    I have left Medical field, except for discussions in RG, and does not feel upto the task.. I am now fully engaged in Linguistics (!), of all things.

    I will try to find out the names of Biostatisticians whom I follow in RG and give them to you. You can discuss with them regarding the variables/parameters to be selected. Most tedious work will be data collection. Which I hope you may be able to enstrust to your Juniors or ex-Students.

    Any way you can start writing the Introduction, lacunae in the problem etc.


  • George Arnold Noble asked a question in Atomic Physics:
    Can Ultra Cold Atom #Physics eg Bose Einstein Condensation et al be used to detect gravitational waves from #space?

    See Links Below for

    Gravational Waves, Bose Einstein Condensate, Magnetic-Optic raps. Ion Traps and Far Off Resonance Traps.

    + 4 more attachments

  • Michael Hornsey added an answer in Plasmids:
    Question about plasmid digested by two-cut-site RE at MSC?

    Here I have a basic question.

    My cutting vector run faster than uncut when cut with MscI and XhoI.

    Who can tell me it could happen in the normal situation?

  • Martín Martínez Villar added an answer in Shock Waves:
    Gravitational shock waves?

    What does it take to produce or detect them? Have the massive black holes that gave rise to the chirp at LIGO created a shock wave? 

    Martín Martínez Villar

    Amrit, look at the data of this paper and see this one. I don't think this could be dust in the Milky Way...

  • Priyanka Panwar asked a question in Pymol:
    How to do virtual screening of a library of ligands through autodock Vina?

    I am able to use vina for docking a single ligand but I have to screen a library of ligands on a protein receptor and don't know how to do it through vina.

    Tutorials available online aren't very helpful. I tried to download Pymol plugin for vina but it doesn't open on my laptop which has a Windows 7 OS. I would appreciate any help on this topic. Thanks

  • Zohreh Riazat added an answer in Zein:
    How can we make zein protein isolate soluble in beverages in order to improve protein content of beverage?

    How can we make zein protein isolate soluble in beverages in order to improve protein content of beverage?

    Zohreh Riazat

    thanks. I will try it.

  • Priyanka Panwar added an answer in AutoDock Vina:
    How to use Autodock Vina for virtual screening ??

    How can I write the program that will do virtual screening using Autodock Vina. Could you please tell me how to do that?

    How do I create a bash script to loop through the ligands and execute the dockings. 

    Vina manual (http://vina.scripps.edu/manual.html#screening) isnt of much help

    Priyanka Panwar

    I am able to use vina for docking a single ligand but I have to screen a library of ligands on a protein receptor and don't know how to do it through vina.

    Tutorials available online aren't very helpful. I tried to download Pymol plugin for vina but it doesn't open on my laptop which has a Windows 7 OS. I would appreciate any help on this topic. Thanks

  • Sandra C. A. Moreira added an answer in Risk Assessment:
    What are a chemical company’s top risks and how likely are they to occur?

    Any chemical company's wide risk assessment process should be responsive to change in the business environment. A robust process for identifying and prioritizing the critical enterprise risks, including emerging risks, is vital to an evergreen view of the top risks. Are there any organizational “blind spots” warranting attention in a chemical company?

    Sandra C. A. Moreira

     C. Lewis Kausel  you mentioned the first thing that came to my mind while reading whole these comments: terrorism. Besides safety concerning the chemicals production, these facilities should also be prepared to handle sabotage or terrorist attacks. These may cause the release of deadly substances for humans and the environment. Nowadays this is one top risk no one should ignore.

  • Reginald L. Bell added an answer in Academic Writing:
    How many citations does it take to indicate an academic article is influential?

    Imagine an article published in 2013 has been cited 12 times, is this good? What does this reflect in terms of the citation trend for this particular article? More importantly, how many citations does it take to indicate an academic article is influential?

    Reginald L. Bell

    Twenty citations of a scholarly article after two or three years is indeed a well cited article!

    Thanks Professor Kahana. 

  • Renaud Lancelot added an answer in R Programming:
    In R, is there any way to read data from the second, third,... sheets of .csv file?

    In R programming, I need to import data from excel file. I converted it to .csv file so that the data import bacame fast. But the next problem came as to I was unable to read data from the sheets except the first one. Is there any way to tackle this? My major concern is that importing large amount of data from excel file takes more time as i have data in only the first two columns. Other columns are left blank. 

    Renaud Lancelot

    If you're on MS Windows, an efficient option to automate the process is to use the package RODBC which allows querying any of the sheets in an MS Excel file (other packages than RODBC provide similar features). The key functions are odbcConnectExcel (for xls files) or odbcConnectExcel2007 (for xlsx files), and sqlQuery (or sqlFetch).

  • Panchatcharam Mariappan added an answer in Differential Equations:
    Hello,I used BVP4c to solve a system of nonlinear differential equations. Is there any possibility of assigning limits or ranges to the function?

    My function values are going negative while i need to restrict it to zero. How do i do that?(optimal control problem)

    Panchatcharam Mariappan

    Please post the function. Let me check and inform you the solution, if I get success.

  • Jeeva Sankar added an answer in Randomized Clinical Trials:
    What to use to check bias in nonrandomised studies?

    newcastle ottawa scale is good for cohort and case control observational studies, but I am doing meta-analysis with both randomized an non randomized clinical trials. some of the non randomized trials have single arms (without comparison) and I dont think Newcastle Ottawa scale can be used here. 

    Jeeva Sankar


    In addition to what Agnik Pal has already mentioned, you can also have a look at an elegant review published in Health Technology Assessment (see pdf). The authors have evaluated all the available scales and tried to identify the 'best' possible tool (Chapter 4). 

    Hope you find it useful. 


  • Valentin Danci added an answer in General Relativity:
    Universe is static!!! Yes or no?

    Space of Universe is static! Yes or no?

    Question: Are there any observations that do not fit into the model static space of Universe, are there any theoretical obstacles to the existence of such a model?

    I assume that the Universe is eternal, infinite and static, it is not expanded and not curved, it is possible to construct a preferred inertial frame of reference in which the CMBR is most isotropic. The matter in this space evolves, but the average density of matter and energy (in large enough volumes) fluctuate within a rather broad range.
    The light in this model is "tired", the speed of light depends on the optical density intergalactic medium. Gravity is also "tired" t.i. weakens a little faster R2. The energy of destroying matter goes into the surrounding vacuum. The excess energy from the vacuum give rise to new particles of matter.

    I state that all the observed cosmological effects can be explained in such a Static Model of the Universe.
    See attached "Basic_Cosmological_Formula_1_En.pdf"

    Dear colleagues, I do not ask, what are the problems faced by other theories (though I would be interested in your opinion on that. The General theory of relativity is not applicable to the entire space of the Universe).

    Valentin Danci

    Erkki wrote:

    "Being objective does not seem to violate Einstein’s STR assumptions, unless you find his “light velocity in vacuum” axiom subjective. Furthermore continuity of space time does not conflict with homogeneity, axioms made by Pauli , Löwdin etc."

    Of course the axiom of “light velocity in vacuum” is subjective!
    And Einstein was wrong to use such axiom, as he stole it from two of his predecessors who used a similar axiom-guess and who were wrong as well:

    1. - Voigt assumed the wave equation of light has a similar form to the wave equation of sound, but he wrongly assumed without proof that light must have the same velocity for any observer in motion. That was utterly illogical, since it does not happen for sound. The velocity of sound is recorded as different between a moving observer and a stationary observer.
    In the same manner, Einstein postulated it without any physical proof of measurements of light's velocity: nobody ever in the whole history up to now, nobody measured it one-way !

    2. - Poincaré assumed that 2 observers exchanging light signals would not know the velocity of it, either way, and they would assume-guess it is identical both ways.
    That was again an illogical and unscientific assumption, and Einstein stole it and used it in his 1905 paper to enforce it as a synchronization method in a poorly set up imaginary experiment.

    Bottom line, today this assumption of a constant velocity of light (CVL) is not only subjective, it is religiously subjective, as part of an established relativistic dogma. Even those scientists who did not use CVL, are now proclaimed by the relativity dogma that on the contrary - they used CVL!!!

    To prove my last statement, see how often you bring up here Löwdin's name along with the CVL axiom. But you still don't understand it:
    Löwdin did NOT use the CVL axiom!!!

    (And even so, his demonstration is also wrong, I showed you many times here why: the assumed homogeneity of space and the obtained Lorentz transformations are conflicting to each other!)

    See the picture attached, a fragment from Löwdin's paper ("Some Comments on the Foundations of Physics") showing clearly that he did NOT use CVL.

  • Senaka Amarakeerthi added an answer in Discrete Wavelet Transform:
    I need EEG emotion database?

    i am interested in Electroencephalography (EEG) and have by an article(Classification of human emotion from EEG using discrete wavelet transform) related to EEG , unfortunately i do not have its data base. tank you

    Senaka Amarakeerthi

    This link might be useful.


  • Farshad Badie added an answer in Analytical Philosophy:
    How do researchers from different fields of research propose conceptual realisation of UNDERSTANDING?

    The 'understanding' is a very complicated and sensitive term. It's quite a long time that I have been focusing on logical specification, representation and analysis of [constructivist] understanding. Now, I feel the need to use the knowledge of the appropriate researchers from different fields (e.g., psychology, neuroscience, cognitive science, learning sciences, philosophy, knowledge processing and cybernetics) to make the logical comparisons between the answers. The question may seem to be very general, but I want the researchers in different fields to make it more specific with regard to their own conceptions and relying on their own policies.  

    Kind regards,

    Farshad Badie 

    Farshad Badie

    Dear Joseph L Alvarez,

    Thank you for your good description. Now I can realise how you have seen and interpreted 'knowledge', 'information', 'understanding' and 'conceptual realisation' from your point of view. 

    All the best,


  • Antonio José Balloni asked a question in Nobel Prize:
    Do you agree??? See: Gravitational waves -GW-: https://lnkd.in/eBbhD8S *** It seems -to me- the "mysterious Ether' would be the gravitational waves--?

    Concerns about Gravitational waves -GW-: https://lnkd.in/eBbhD8S

    *** It seems -to me- the "mysterious Ether' would be the gravitational waves -GW- As presented in the above video ...

    The Michelson and Morley Interferometer -designed in 1907- to detect the ETHER and, FAILED, have arrangement similar to that shown in the video above -GW-.

    The mentioned interferometer gave the Nobel prize to Michelson Morley Experiment to detect the existence of ether, but it has failed...- =============================================

    Por Antonio José Balloni, 13 de Fevereiro, 2016

  • Khalid El BAIRI added an answer in Chemotherapy:
    What is more common in chemotherapy : High-doses or Low-doses?

    For instance, in FOLFOX4 the recommended dose:

    Oxaliplatin 85 mg/m² IV infusion 2 h. Is this high or low dose?

    Leucovorin 200 mg/m² IV infusion over 120 minutes. Is this high or low dose?

    Fluorouracil 400 mg/m² IV bolus 2 min. Is this high or low dose?

    Why is better Fluorouracil 400 mg/m² over 2minutes than Fluorouracil 200mg/m² over 4minutes?

    Khalid El BAIRI

    Recently, metronomic chemotherapy is recommended by experts in clinical oncology

  • Lilliana Ramos-Collado added an answer in Educational Systems:
    How should / could we improve the Educational System, to adapt modern times, and future generations?

    Most would agree that Education plays a fundamental role in solving many of the humanity's current problems.

    I believe in a better World.

    Mass education for all youngster can play a good role in the near future.

    Should we change our system?

    Should we act on University level?

    Should we act transversally from kindergarten, through basic education?

    I should like your valuable contributes.

    Lilliana Ramos-Collado

    Thank you, Louis, for your very wise comment.

    Best regards, Lilliana

  • Prem Baboo added an answer in Electrochemical Analysis:
    What does it means when the value of the current density in oxidation process is different from the value in the reduction process?

    In Electrochemical analysis (chronoamperometry figure) , the diagram between the current density and time. 

    Prem Baboo

    Dear Rehab

    you are undoubtedly already familiar with the general idea of oxidation and reduction: you learned in general chemistry that when a compound or atom is oxidized it loses electrons, and when it is reduced it gains electrons.  You also know that oxidation and reduction reactions occur in pairs: if one species is oxidized, another must be reduced at the same time -  thus the term 'redox reaction'. 

    Most of the redox reactions you have seen previously in general chemistry probably involved the flow of electrons from one metal to another, such as the reaction between copper ion in solution and metallic zinc:

    Cu +2 (aq) + Zn(s)  →Cu(s)   + Zn+(aq)

    In organic chemistry, redox reactions look a little different. Electrons in an organic redox reaction often are transferred in the form of a hydride ion - a proton and two electrons. Because they occur in conjunction with the transfer of a proton, these are commonly referred to ashydrogenation and dehydrogenation reactions: a hydride plus a proton adds up to a hydrogen (H2) molecule.  Be careful - do not confuse the terms hydrogenation and dehydrogenation with hydration and dehydration - the latter refer to the gain and loss of a water molecule (and are not redox reactions), while the former refer to the gain and loss of a hydrogen molecule. 

    When a carbon atom in an organic compound loses a bond to hydrogen and gains a new bond to a heteroatom (or to another carbon),  we say the compound has been dehydrogenated, or oxidized. A very common biochemical example is the oxidation of an alcohol to a ketone or aldehyde:See Fig1(aatached)

     When a carbon atom loses a bond to hydrogen and gains a bond to a heteroatom (or to another carbon atom), it is considered to be an oxidative process because hydrogen, of all the elements, is the least electronegative.  Thus, in the process of dehydrogenation the carbon atom undergoes an overall loss of electron density - and loss of electrons is oxidation.Conversely, when a carbon atom in an organic compound gains a bond to hydrogen and loses a bond to a heteroatom (or to another carbon atom), we say that the compound has been hydrogenated, or reduced.  The hydrogenation of a ketone to an alcohol, for example, is overall the reverse of the alcohol dehydrogenation  shown above.  Illustrated below is another common possibility, the hydrogenation (reduction) of an alkene to an alkane.See Fig 2(attached)

     Hydrogenation results in higher electron density on a carbon atom(s), and thus we consider process to be one of reduction of the organic molecule.The phenomenon happen over a region where Oxide density is higher than average, In higher density region, the CMP pad pressure is reduced and hence RR is less that of the regions with lower density.

    Please find attached herewith related articles,


    Prem baboo

    + 3 more attachments

  • Yolanda Valencia asked a question in Multiculturalism:
    Would an Interdisciplinary BA be an asset for an employer to hire you?

    Today’s marketplace is in search for more than single specialized graduates. Jobs opportunities are offered to individuals that are ready to solve problems in innovative ways and who are competent in working with multicultural and multidisciplinary teams. A contextualized curriculum will aid students, through cooperation, to fully embody the complexity of their world.

    Is this the kind of education that will give students the tools to constantly adapt and innovate in this kind of world?

  • Annangi Subba Rao added an answer in Soil Analysis:
    Is it possible for a soil sample to be stripped off of a particular nutrient, if so how?

    i intend to remove a Zn from a soil sample before planting a crop in the soil.

    Annangi Subba Rao

    Dr.Praveen Kumar you are right.The other micronutrients cations will also be removed.I think it is possible to supplement those nutrients at recommended rates.If any selective Zn complexing and removing agent  is there,it would be better.

  • Houxiang Shan asked a question in Zircon:
    Elevated δ18O signals can only screen out recycling of altered surficial rocks at specific paleo latitudes?

    It is generally considered that significant deviations of zircon δ18O values from the mantle value directly or indirectly result from intra-crustal recycling. Intra-crustal recycling is defined as the interaction of magma with supracrustal materials that ultimately inherit their evolved δ18O values from low temperature processes on or near the surface of the Earth (Valley, 2005). I don't know why elevated δ18O signals can only screen out recycling of altered surficial rocks at specific paleo latitudes. I mean elevated δ18O signals can  screen out recycling of altered surficial rocks, which is not necessarily at specific paleo latitudes. What do you think about it? Thank you.

  • Issa Issa asked a question in Ottoman Empire:
    I need English fiction distorted the image of Ottoman Empire?


    I am doing a research paper related to the English literature and Ottoman Empire, and I need some English fictions distorted the image of  the Ottoman Empire. So if you please help me with this point and suggest me some novels may help me in my paper.

  • Renaud Lancelot added an answer in Correspondence Analysis:
    Can i do correspondence analysis for insignificant relation cases???

    If there is no associate between two variable, what would be the next analysis to express negative relation between that two variable?  

    Renaud Lancelot

    What is the nature of your variables ? If quantitative, I'd start with a scatter plot together with a smooth curve showing the relationship between the 2 variables. If qualitative, a chi-squared test will give you a first idea. Of course in this case you can do a correspondence analysis on the contingency table crossing the 2 variables. This is the sophisticated version of the chi-squared test, with the additional advantage that you can plot the categories and individuals.

    Beware: "insignificant" is not synonymous of negative

  • Ricardo Augusto Mendonça Vieira added an answer in Animal Science:
    Does anyone have experience with sheep In Vivo digestibility Essay?
    How can I calculate the feed unit by kg of dry matter (Unité fourragère Leroy), the gross energy (kcal/kgOM), the digestibility of energy (dE), the Digestible energy, the metabolizable energy (ME) and digestible crude protein (dCP) in vivo digestibility essay.
    Ricardo Augusto Mendonça Vieira

    Please, Dr Yetongnon, let me know if you find the papers hekpfull. I would greatly appreciate a feedback criticism.

  • Annangi Subba Rao added an answer in Sustainable Agriculture:
    The soils are calcareous and sodic. Cotton and Red gram major rain field crops. Groundwater is poor in quality. What could be the management options?

    The yield levels of crops are also low

    Annangi Subba Rao

    Dr.Manikadan, what is the problem in foliar application of micronutrients,or even NPK in rainfed crops like cotton?

  • Matt Jans asked a question in Neighborhood Effects:
    Are there accepted geographic definitions of ethnic enclaves and areas with racial/language concentrations in California?

    Demography is not my specialty, and I'm new to the study of "neighborhood effects" and geographic clustering by race/ethnicity and language. I'm wondering if there are some (even if more than one) accepted definitions of what it means for an area to be an "ethnic enclave" or a "high density" area (e.g., high Korean population). I'm sure there are many, but are there a few that rise to the top as the most commonly used/cited? 

    Ideally, these would be either in the form of a calculation I could make based on ACS or Census tract/block level estimates, or a listing of tracts/blocks or ZIP codes that are considered to be enclaves. 

    I've done some lit review and Googling but can't seem to find the kind of definition I'm looking for. Most of what I find seems to be either qualitative discussions of enclaves or one-off definitions used for specific studies. Just want to be sure I'm not missing any obvious "industry standards."

    My study is of California specifically, but any leads would be helpful, even if national or international. 

    Thanks in advance!

  • Etienne Lebard added an answer in Spine:
    Why the effect of force is different than the effect of displacement?

    I am modeling a human spine. I am applying displacement from top side and fixing the bottom and the model is working properly but when I change the displacement to concentrated force it is dying because of max penetration error and element distortion. I tried to apply very very minute amount of force which again caused my model to die. I wanted to know why the effect of force and displacement should not be the same in a model while both are at the same direction?!

    Etienne Lebard

    I can't say for sure since I didn't see how you defined your model, but for exemple in undeformable solid statics, it is easier to determine the forces acting on multi-part body in a certain configuration (angles, positions of parts respectively to one another) than doing it the other way around. I suppose it is the same for Abaqus regarding deformable solids.
    Apart from that, if your geometry is not 1D, a force in a certain direction won't necessarily produce a displacement only in the same direction, especially if it's concentrated.

  • Iman (Abdollah) Dehzangi added an answer in Artificial Neural Networks:
    Where can I get a good implementation of Deep Neural Network in R or Python?

    I am planning to use DNN in my research and I just wonder where can I find a good implementation in R or Python? Something that has Recurrent Neural Network or Convolutional neural network would be even better.

    Iman (Abdollah) Dehzangi

    Thanks Raida,
    I will check them for sure. It is greattttttttttt .