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

  • Raji nr added an answer in Sign Language:
    Can anyone send me some articles for all Sign Languages?

    I do a research for all Sign Languages. 

    Raji nr

    I would like to know more about your research.Are you doing it in ASL?

  • Alireza Ousati Ashtiani asked a question in Electroless Deposition:
    How to improve adhesion of electroless copper to polystyrene?

    I would like to use copper electroless deposition method on polystyrene. I tried oxygen plasma surface treatment but no luck. I can only observe islands of copper, and adhesion is very poor, too.

    any ideas or recommendations is highly appreciated.


  • Refik Kanjhan asked a question in Cell Type:
    Why copper is toxic to the cells? Why is copper more toxic to some cells than others?

    I would like to know about mechanisms of copper (Cu2+) ions toxicity in different cell types. Any suggestions?

    thanks, Refik

  • Azzam K Almosallami added an answer in Gravitational Field:
    Is the non locality of the gravitational field energy a serious problem for General Relativity (GRT)?



    "Although there is no room for such a thing in the energy–

    momentum tensor T, it is clear that there are situations where a ‘disembodied’

    gravitational energy is actually playing a physical role.

    Imagine  two massive bodies (planets, say). If they are close together (and we can

    suppose that they are instantaneously at rest relative to each other), then

    there will be a (negative) gravitational potential energy contribution which

    makes the total energy, and therefore the total mass, smaller than it would

    be if they are far apart.  Ignoring much tinier energy effects,

    such as distortions of each body’s shape due to the gravitational tidal field

    of the other, we see that the total contributions from the actual energy–

    momentum tensor T will be the same whether the two bodies are close

    together or far apart. Yet, the total mass/energy will differ in the two cases,

    and this difference would be attributed to the energy in the gravitational

    field itself (in fact a negative contribution, that is more sizeable when the

    bodies are close than when they are far apart)." 


    The same problem was also rised by Thirring, Kalman and Feynman in the FGT theory, they inserted the gravitational energy in the tensor equations...

    It is a problem of paramount importance which prevents the General relativity theory from describing any motion in which the hamiltonian is time dependent or rather in case of non isolated systems, or in case of non stationary interactions between different bodies.

    The attempt to model a free falling body in a gravitational field for GRT seems impossible.

    GRT has been tested  only for static or stationary systems where there is not a net exchange of energy (excluding gravitational radiation)

    Don't we need another GRAVITATIONAL THEORY which includes the results give by GRT in order to explain with a better accuracy the simple phenomenon like the free falling of a mass in a gravitational field?

    Azzam K Almosallami

    Charles Francis,

    If you have a courage, then reply to me by physics not by words. Prove to all here my theory is wrong. Bring any experiment that in contradiction with my theory.

  • Edwin F Ullman added an answer in FACS:
    Are there any protocols to unlabel (separate bound Ab from cells) live cells immediately after FACS sorting?

    I am using anti-human IgM to sort B cell hybridoma cells lines. After sorting it seems that this particular cell line does not like the Ab or the antibody might be activating some death pathway. I would like to try to take the Ab off and see if that makes a difference.

    Edwin F Ullman

    Try adding human IgM to cells sorted with anti human IgM Fab fragments.  The Fab should dissociate from the cells and bind to the free IgM.  You can monitor the process by using FAM labeled Fab and monitoring cellular fluorescence.

  • Julia Hazel added an answer in Scripting:
    I need volunteers for testing a R-script I have written (with help from colleagues) - can someone help?

    I have used existing packages and written some functions to extract the metadata from the video files and automatically create a data frame with the date, time and image ID for each video clip, thereby avoiding the need to type in the data manually.

    Since the script will be supplied as supplementary material for a paper, I prefer that the script is tested thoroughly before handing it in.

    Let me know if you would like to test the script for me and I will give you access to the script and the folder containing the video clips. 



    Julia Hazel

    Might be helpful to recap: If you want to analyse the animal's behaviour that the camera recorded, you really need the date-time of *image* creation. If you use any file metadata instead of *image* metadata, your own analysis could be right or wrong - maybe small difference that is not obvious. Generalising your script could be completely UNreliable for other users across different computer platforms where the file metadata can be treated differently.

    From a quick search I see exif information for AVI is not standardised. Maybe you can check the details for your particular camera(s) e.g. some cameras record 'sidecar' files containing video metadata. If that's the case, your script could probably access the relevant metadata by matching sidecar and image file names. Of course this would be specific to your camera(s) and your computer system. Good luck with all this.

  • Francesco Pomponi added an answer in LCA:
    Is there a method/model to calculate distances in LCA including the empty return travel?

    How can I consider the intermodal exchange in the LCA? Are there any studies about it? Thanks!

    Francesco Pomponi

    I agree with Claudia, a very good idea. If your context is Europe, the UK Government has published such guidelines as well which thoroughly give you carbon conversion factors or carbon dioxide equivalent emissions for a wide range of elements. You can find them freely available on the Government's website [authors Hill et al., 2011 - DEFRA]

  • Victor Hugo de Oliveira Segundo added an answer in Cardioprotection:
    Which mechanisms are involved in exercise-induced cardioprotection?

    The literature shows that myocardial antioxidant capacity, cardiac Heat Shock Porteins, Nitric Oxide, ATP-dependent potassium channel function, and opioid system activation are related to this, but also turns it inconclusive in some original articles or systematic reviews.

    Victor Hugo de Oliveira Segundo

    Thanks Samuel,

    I will see that too.

  • Rami Alrezk asked a question in Off-Label Use:
    Is it legal to start RCT on brand name drug for investigational off-label use? or I need NDA?

    I am planning RTC for brand name medication to investigate it for off-label new indication that I found to be very useful--anecdotally 

    Also what is the appropriate ways to contact the pharmaceutical company to get  the drug free of charge? and How can get placebo? 

    Thank you for help 

  • George Stoica added an answer in EFL:
    What role does learning about culture have for both the knowledge and motivation of EFL students?

    Most people seem to agree that learning about culture is part of learning a language, but the better we understand the ROLE that learning about culture plays, the more focused we can be about what parts of culture to teach.

    How important is learning the cultural meaning behind idioms?  How important is cultural knowledge for increasing motivation to learn?  Are there other benefits to teaching about native speaker culture?

    George Stoica

    It might be a small burden for a kid to learn a foreign language and, in the same time, the essentials of a new culture. Everything in good time: learn the language first, and then you have a basis and a better chance of understanding the country's history & culture.

  • Omar Marchant added an answer in ESL:
    What are the theoretical and empirical relationships between developing a multicultural view in schools and a growth mindset?

    Researchers recently focus on studies for developing growth mindset in schools. A review of the literature suggests the processes and variables involved in a growth school mindset may be similar to those that develop a group open to a multicultural view in schools. Does anyone have articles referencing studies connecting multicultural views in schools or ESL teacher development with Dweck's concepts of growth school mindset? Thank you in advance.

    Omar Marchant

    salaam: I have attached a file regarding Bilal raḍiya 'llāhu ʿan-hu, you may find interesting the narration regarding his betrothal. unlike the reported activities of so called Islamic groups today (in many instances inconsistent with  the Quran and sunna) the example of the prophet Mohammad radialanhu anhu and his companions exemplifies "cultural/international diversity" as well as excellent manners, under extreme conditions. these historical documents are little understood today, and an excellent source of sociological material. enjoy

    + 2 more attachments

  • Chao-Chen Lin added an answer in Fluorometry:
    Difference between emission/excitation spectra?

    In fluorometry, when do we take the emission spectra and when do we have to take the excitation spectra of a particular sample....i mean theoretical definition i understand, but practically when and how do i differentiate them?

    Chao-Chen Lin

    The emission is more straightforward and commonly used. Gelija has given a thorough explanation.

    Excitation spectra are particularly useful in the following cases:

    1. When there are two emission bands (or an unnaturally broad one). If the excitation spectra of the two bands are identical, there is an excited state process, e.g. proton transfer, electron transfer. Otherwise, two ground state species are present.

    2. If the excitation spectrum deviates a lot from the absorption, emission at the observed wavelength may originate from some strongly-emitting impurities.

    3. If the excitation spectrum deviates from the absorption only at shorter wavelengths, there are extra photophysical (e.g. internal conversion) or photochemical (e.g. dissociation) processes going on, which do not go through the usual emitting S1 state.

    4. With a strongly scattering sample, such as lipid vesicles, for which the absorption cannot be properly measured.

  • Kenneth R. Harris added an answer in Activation Energy:
    What kind of concentration dependence exists for the activation energy?

    Dear Colleagues! We are interested in the concentration dependence of the activation energy. For example, the activation energy of viscosity or conductivity of solutions. However, we can not find publications on this topic. Tell me please!

    Kenneth R. Harris

    Probably because activation energy theories do not well describe such processes and more sophisticated approaches are required. The problem is that apparent activation energies are much smaller than those for chemical reactions or solid state transport processes. Hence they imply that a much larger proportion of the molecules should be in the activated state than are consistent with approximations made in Eyring's theory.

  • Saidul Islam added an answer in FLUENT:
    How do I deal with this error message in ANSYS FLUENT?

    Any ANSYS FLUENT users here, please how do i deal with this error message "Error: received a fatal signal (Segmentation fault).
    Error Object: #f" . Am actually solving melting, evaporation and reaction problem simultaneously which i can provide more details if you wanna know more. Your contribution will be much appreciated. Thank you

    Saidul Islam

    Actually, what types of UDF you are using? May be I can help you out. You can share your UDF and then I will have a look.

  • Patricia Dobrez added an answer in Comparative Religion:
    What is the most suitable means of inferring meaning and function for rock art?

    How much weight should be placed on ethnographic analogy?

    Direct interpretation of subject matter?

    Cross cultural studies of rock art?

    Cognitive neuroscience?


    Comparative religion?


    Patricia Dobrez

    I agree with Derek: we should be asking what it is the brain, and in particular our visual system, can tell us about the way we see (neurophiz, cognitive psych). We need to begin by asking ourselves what exactly is it we are looking at in terms of the marks on the rocks. And we should be looking at the landscape, not failing to take into account that this may have changed since the images were made. While the question of how much we can rely on ethnography has been seriously raised, there are things that we can reliably learn from historical records, commentary and speculation. We can be in no doubt that there are rock art universals (the very act of marking is a universal) and, whatever our research preoccupation, it's helpful to keep them in mind.

  • Sunwoo Kang added an answer in Gaussian (Software):
    How can I confirm singlet ground (S0) (Three types) and triplet gound (T0) state in carbene (see attached file) using G09?

    How can I confirm singlet ground (S0) (Three types) and triplet gound (T0) state in carbene (see attached file) using G09?

    Sunwoo Kang

    S0 = ground state calculation of sinlget

    S1 = excited satte calculation of singlet (TDDFT)

    S2 = doubly excited state calculation (SAC or CCSD(T), CASPT2 method may help)

    T1 = ground state calculation of triplet or TDDFT calculation using singlet state

    Hope this help

  • Guy Jakeman added an answer in Rationality:
    How do the economists define self-interest and rationality?

    How do the economists define self-interest and rationality so as to make these concepts different from the animal instincts, beast behaviour, and barbarism? What is that which forms and what is that which does not form the self-interest? Moreover, are these the behavioural guides for all individuals? Are these the collective guides for policy making? 

    Given the propensity for free riding in each economic-beast, does not the collective policy results into a collective free riding of those who make policies over those who do not?

    Guy Jakeman

    "is investment determines saving, not the other as we believe the economic orthodoxy"

    You cannot build something without first producing the necessary materials and not consuming them. Hence, you must first save resources before you can possibly use those resources for your investment project.

    "But capitalism needs financing demand to avoid idle capacity and unemployment."

    I have no idea where such an assertion comes from. Can you please expand on what you mean by this?

  • David Farringdon Spencer added an answer in Paraffin Embedding:
    Could any one give some advise on amplifying DNA extracted from paraffin embedded tissue?

    I have added DTT to the extraction buffer, and or I have boiled DNA prior the PCR reaction,  I have also used kits and no-kits for the extraction but the PCR results are still poor.

  • Dipangkar Kundu added an answer in Satellite Data:
    Do we need to focus direct application of satellite data for catchment-scale (10- 1000 sq.km) hydrological modelling?

    Spatial and temporal resolution of satellite data/ remotely sensed data favors more direct application of large-scale hydro logical modelling due to spatial comparability  of the modelling scale. Therefore, not so suitable for catchment-scale application

    Dipangkar Kundu


    A direct application would be not converting satellite data to other physical entities before being applied to the model. For example, precipitation, LST. Finer resolution of Landsat does not define the applicability of all other products available. As I mentioned earlier  "freely accessible or low-cost satellite data are often at a coarse spatial resolution, low vertical accuracy, short repeat cycle and global coverage"

  • Witold Janik added an answer in CAD-Modeling:
    How can I determine determine mesh density of a cad model in stl file and how can I use the mesh density to define its stiffness parameters?

    I have a cad model of a bone and a patient-specific guide attached to it in stl file. (Imagine an object clip on top of another object but not rigidly attached to it).
    -- How can I import the model as an stl file into MATLAB?                                   --  How can I create a mesh for the cad model?
    -- How can I determine their mesh density?
    -- How can I use this to determine the stiffness parameters?

    --How can I generate the coordinate of the vertices and normals of each triangles of the stl file?

    Witold Janik

    *.stl is simplified model, application is in 3D printing... Try to obtain native file of the software that is used for FEM. However in medical approach common file gathered from tomography is *.stl, according to sectioning done throug a tissue... In this case the reccommended solution is to set a precise leyers discretization and export to the universal format (*.stp,*.igs ) or native format of the software used for FEM (ex. shoud handle with data consistency - idelized part -> meshing -> boundry conditions - data deck record for NASTRAN). Furthermore the crossection of a bone have comlex pore structure with diverse density... The way is to deterimine proper stiffness matrix elements - bone sampe destructive tests in order to properly describe material, especially Young Modulus. Propeper meshing shoud be prepared with larger tetahedral ctetra(10) FE close to section core and smaler to layer surface. Try from the core 1mm to 0.1mm to the layer surface (try mesure the pits quasi diameter and assign range to average results). An sirious computing power station is needed. The best way is to try with full data of a foam bone structure, but obviously... too complex, but maybe microscanning of selected area and proper scalling is worth to give a chance...

  • Refik Kanjhan added an answer in Secondary Antibodies:
    In the Immunofluorescence technique, what is the range of absorption and emission wavelengths PI and secondary antibody of Nestin protein?

    In the Immunofluorescence technique, what is the range of absorption and emission wavelengths PI and secondary antibody of Nestin protein?  

    Refik Kanjhan

    Dear Nazanin,

    That is up to you and depends what secondary (fluorescent molecule attached) antibody you choose. There is a huge range but usually comes at 4 main groups such as Alexa 488, cy3, cy5.

    best wishes,


  • Laura Diaz added an answer in Pyrolysis:
    How can I clean a quartz tube that contains some borosilicate glass parts?

    The quartz tube is used for pyrolysis in a horizontal furnace and has char and wax residues. I used to clean it inside a furnace at high temperature and worked fine however with the new borosilicate parts I cannot go over 250oC and that is not enough to clean the residue. I have also tried to rise it with acetic acid but there are some parts that are not accessible and cannot be scrub. Thanks!

    Laura Diaz

    thank you very much for your suggestions. I'll try increasing the temperature and see what happens but I'll probably have to use the alkali solution as well. Thanks for the article it was useful.

  • Clinton Rissmann added an answer in Greenhouse Gases:
    Can anyone help with estimation of net greenhouse gas emission from a paddy field?

    Irrigation is ​the biggest ​contributor in ​green house gas ​emission in ​agriculture. I ​want to ​know how to ​calculate or ​estimate net ​green house gas ​emission from ​the paddy feild.​ We mostly grow ​rice in bunded ​fields and ​maintain 5-10 ​cm of water ​level in each ​bund. ​

    I want to ​know this as we ​wish to reduce ​the GHG ​emmision from ​the feild by ​adopting ​different and ​better ​irrigation ​method over ​this old flood ​irrigation ​system. ​

    Clinton Rissmann

    Dear Anand,

    There are various direct measurement methods available for measuring CH4 and other GHG flux. I used a Tunable Diode Laser and a West Systems mass spectrometer for ppb/'s measurement of CH4 flux. I also measure CO2 and H2S. These technologies have come a long way in the last 10 years and much of the criticism of the accumulation chamber technique, which predates these advances, for measuring flux is now unfounded. I hope this helps. Regards, Clint

  • Djeghader Mohamed asked a question in Speech Recognition:
    Is ANN much good in prediction of classification on speech recognition area (noisy envirenment)? if yes , witch kind of algorithm is better?

    Artificial neural network

  • Nikola M Stojanovic added an answer in Cytotoxicity Assays:
    I am planning to use cycloheximide for inhibiting protein synthesis in HeLa cells. What concentration should I use?

    I need to know what concentration of cycloheximide can be used in HeLa Cells without killing the cells. According to Santa Cruz Biotech that sells this compound, IC50 value of CHX is 532nM for Hela Cells. I have also read that this value is cell line specific. I have come across papers that have used it at 10-30ug/ml for this cell line. But I also calculated that 532nM corresponds to 0.14ug/ml conc of CHX. So they are using it at very high levels. I want to avoid doing a cytotoxic assay, so I would need valid references for supporting the use of a specific concentration of CHX. I plan to use it for 3-4 hours in HeLa Cells having overexpressed luciferase and want to inhibit any protein synthesis after i give the cells Heat Shock. Also, I think I have to add CHX after Heat Shock treatment, but please confirm if it is otherwise.

    Nikola M Stojanovic

    Try few concentrations, not only one that's always good.

  • Kenneth M Towe added an answer in Climate Change:
    Are there authentic published work confidently pinpointing the sole anthropogenic factors contributing to Climate Change?

    Combined natural and anthropogenic factors (geologically recent phenomenon) govern Climate Change. It is, therefore, of paramount importance to discretely recognize the role of humans in Climate Change and to plan efficient strategy to mitigate it.

  • Rafik Karaman added an answer in Enzymes:
    What is the relationship between Km and Kmax to Substrate and Enzyme concentration?

    What happen to Km when the substrate concentration level increased?

    Rafik Karaman

    Dear Thilina,

    Please read the following text:

    The model takes the form of an equation describing the rate of enzymatic reactions, by relating reaction rate v to [S], the concentration of a substrate S. Its formula is given by

    v = Vmax [S]/Km + [S]

    Here, represents the maximum rate achieved by the system, at maximum (saturating) substrate concentrations. The Michaelis constant Km is the substrate concentration at which the reaction rate is half of Vmax.

    The Michaelis constant Km is the substrate concentration at which the reaction rate is at half-maximum,and is an inverse measure of the substrate's affinity for the enzyme—as a small Km indicates high affinity, meaning that the rate will approach Vmax more quickly. The value of Km is dependent on both the enzyme and the substrate, as well as conditions such as temperature and pH.

    Therefore the relationship between Km and [S] is an inverse.

    There is no Kmax, there is Vmax as shown in the above equation.

    Hoping this will be helpful,


  • Tawanda Machingura added an answer in Ethics:
    Could people comment on the moral imperatives in caring for involuntary psychiatric patients?

    I am working with South Australian law but am interested in international law.  Who are the carers?.  What support do they receive?   Have used deontological and utilitarian ethics, where does ethic of care come in?  How can the needs of the patient be balanced with the needs of carers, families and communities?  Stereotyping of the patients and their needs is a  problem. 

    Tawanda Machingura

    Being "involuntary" also known as "being under the Act" is an intervention and a protective means available across the world for people who are severely affected by a mental illness.  The principles are based on The United Nations Principles for the Protection of Rights of People with Mental Illness and for the Improvement of Mental Health Care 1991. The "carers" are defined in the Act-so that answers who is a carer. Most mental health services provide holistic care based on the systems theory and would provide services for both the "patient" and the "carer".  

  • Lebreton Florian added an answer in Cultural Anthropology:
    Which cultural studies theories would best describe the hacker subculture?

    Which Cultural Studies philosophers and which concepts would be best used to examine and analyze the Hacker subculture?

    I ask only because the hacker subculture is really vague and has been flesh out to a certain degree in graduate studies but not in undergraduate studies

    Lebreton Florian


    To complete precedents posts, I can recommand you 3 special references on "Hacker subculture" which i deeply used for working about "space hacking" (urban exploration, etc.).

    Borden I, Kerr J, Rendell J, Pivaro A (eds),The Unknown City: Contesting
    Architectural and Social Space (MIT Press, Cambridge, MA)
    Raymond E S, 2005 How To Become A Hacker
    Levy S, 1984 Hackers: Heroes of the Computer Revolution
    (Penguin, London

    All the best,


  • Sally Howard added an answer in Social Pedagogy:
    How do teachers deal with mismatch between belief and practice?

    I'm interested in how teachers might articulate a particular 'belief ' about teaching and learning - yet their practice seems to be at odds with this 'belief' ( observed practice) . My interest lies within the teaching of science and the assessment of inquiry skills. 

    Sally Howard

    Thank you for these papers. They are useful in terms of 'self belief ' and this is part of what I'm interested. However, I think I'm seeking to understand more about the teachers underlying belief about how learners learn best  and the way assessment influences the the way teachers teach - It seems that what is stated as their belief about how learns learn best is not matched by practice. It seems practice is heavily influenced by assessment even when there is 'freedom' to teacher in a different way. V