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

  • Eman Younis added an answer in Random Forests:
    How can I get code of random forest clustering in R?

    How can I get code of random forest clustering in R?

    Eman Younis · Minia University

    Hi Sultan,

    You can use Rattle package  with R and it also has a visual user interface. It has an implementation for various clustering and classification models. In addition, it enables you to create and test your models.

  • Jian Fu added an answer in Fourier Optics:
    What is the relationship between interference and imaging?

    In classical optics or Fourier optics, we use the Fresnel law or diffraction theory to explain the imaging via a thin lens. The interference phenomenons like the Young's Double-slit interference can be explained by the diffraction theory. 

    In quantum theory, interference derives from indistinguish. The quantum imaging (entanglement ghost imaging) can be explained by the two photons interference. 

    In the classical or quantum optics, what is the relationship between interference and  imaging?

    Jian Fu · Zhejiang University

    I agree "Entanglement is not interference", but don't agree  "... leads to the change of the state of the second photon."  Bell inequality does not close the question of quantum completeness. "Spooky action" is forever uncomfortable.

  • Charles Nwamba asked a question in Heat Treatment:
    Do you need heat treatment of nickel before it can be used as a counter electrode?

    Is treatment needed before nickel can be used as a counter electrode?

  • Monica Ihli asked a question in Mixed Methods:
    Information Retrieval: What Analysis May Be Used to Compare Result Sets?

    I would like to explore methods for re-ranking result sets retrieved using a term-based query against a database of bibliographic records. I believe that this additional layer of processing could improve a user's information-seeking experience by helping them to more find easily find articles relevant to their need.

    An alternative implementation is to exclude records from the result set which, although contain the search term, fail to meet other criteria.

    In either case, am looking for existing literature which could help me identify a suitable method of analysis for comparing one set of ranked results to another. I have found studies in which a subject matter expert codes each individual record returned in a result set as relevant or not, in order to compute precision and recall. This may be one strategy, but I am not sure if this alone will really be able to describe and express the differences between two result sets, or the differences in how they are ranked (at least for some arbitrary number of results returned-- it could become unfeasible for a human to evaluate thousands of results, for example.)  I am also considering the value of a mixed method approach, in which I integrate more qualitative assessments of user satisfaction with what they feel to be the quality of results retrieved. 

    I would appreciate any suggestions for literature or methods to consider for this type of research. Thank you!

  • Dipjyoti Chakraborty added an answer in Neomycin:
    How can we overcome seed borne bacterial contamination in cotton?

    We are working on plant tissue culture in cotton. The present bacterial contamination is seed borne (Gram -ve, cocci, in chains). We have tried to overcome it with 0.1% HgCl2, 0.1% SDS as well as with different concentrations of NaOCl, but still unable to get rid off it. Additionally we also tried 70 to 100% ethanol along with flaming it, but still the problem persists. Out of the antibiotic we tried (ampicillin, kanamycin, cephotaxime, carbenicillin, neomycin, streptomycin, erythromycin and penicillin), only neomycin we found as effective to control it, but this unnecessarily kills seed and explants also.

    Dipjyoti Chakraborty · Banasthali University

    I think antibiotics would be the only option if the bacteria is not on seed surface as your surface sterilisation techniques are ineffective. If you have isolated the bacteria why not send to a diagonistic lab - they will identify it for you and may also suggest the correct antibiotic.

  • Jay L. Lemke added an answer in Education Science:
    What is the classroom interaction in a special science program class?

    Does the integration of technology affect the interaction?

    In the Philippines, what are the aspects of teacher-student interaction, that I should investigate or give attention to?

    Jay L. Lemke · University of California, San Diego

    I advise you to investigate the emotional engagement of students in the learning process in the classroom. You could compare this with their engagement in small groups (inside or outside the classroom), e.g. study groups or homework groups, or to their engagement in online learning. Good luck!

  • How can I assess the image registration accuracy in remote sensing?

    Can anyone help me with that?

    Parastoo Hosseini · University of Toronto

    Thanks. The thing is I used GCPs to register my image. The projection is UTM. I have been asked to change the projection to Lambert Conformal Conic and assess the image registration accuracy.

  • Patompong Ungprasert added an answer in SIRS:
    Can I pool standardized ratios (SMRs/ SIRs) and ORs + RRs in meta-analysis:?

    In Meta-analyses: Can standardized ratios (SMRs/ SIRs) be pooled with ORs or RRs (not standardised)? Has anyone done this? any supporting reference?

    Best wishes, Jonas Ludvigsson

    Patompong Ungprasert · Mayo Foundation for Medical Education and Research

    I have done that but not sure if there is an evidence to support.

  • Andrew Messing added an answer in Likert Scale:
    Can anyone suggest better alternatives to the Likert type scale?

    Likert scale gives a fixed numerical value to a varied quality of perceptions that the participants usually tend to group under the same number/value. Is there any other scale that overcomes this shortcoming?

    Andrew Messing · Harvard University

    I think it is important to be, well, mathematically rigorous when using terms like continuity in the context of statistics and data analysis. In particular, "continuous" as used in the context of e.g., discrete vs. continuous distributions is not the same "continuous" we find in "continuous rating scales". In my experience, many researchers using statistics have either not taken calculus courses or do not recall much from them, and in particular are wont to underestimate just how far from continuous almost all data in any science that might use likert-type scales are. The rationals, for example, are infinitely dense (between any two rational numbers, there are infinitely many more rational numbers). They are not continuous, of course, because there are infinitely many irrational numbers between an two rational numbers (without going into Dedekind cuts and a rigorous definition or derivation of the reals). Thus putting a scale from 1 to 100 with ticks every ten or twenty integers certainly can seem continuous (after all, the real number line is depicted this way), but respondents are unlikely to indicate multiples of transcendental numbers or irrational numbers. Perhaps the mathematician in my is being needlessly and overly precise (particularly because we talk about "approximating" uncountably infinite distributions with finite data points despite the fact that this is impossible and its impossibility irrelevant).

    In addition to fuzzy sets, numbers, and probability, there are other quantitative methods designed from the ground up for data including those gathered by Likert-type scales. Item Response Theory (IRT) was big for a while and then sort of fizzled out, but has recently seen something of a comeback thanks perhaps to the incorporation of modern statistical methods as found in e.g., Multidimensional Item Response Theory (Statistics for the Social and Behavioral Sciences) or Bayesian Item Response Modeling: Theory and Applications (Statistics for the Social and Behavioral Sciences).

    Then there are the other scaling methods, such as optimal scaling or multidimensional scaling. I tend to like MDS or related methods namely because I tend to favor classification & clustering algorithms, but while these are often good for categorical data in general, they loose much of their value when one uses a unidimensional ordinal scale.

  • Matthew Flanders asked a question in Dark Matter:
    Are there any current works addressing the possible relation of extra dimensional branes and dark matter?

    Although I am very much a novice, i find it very interesting to consider the implications of dark matter being the result of gravity "spilling over" from extra dimensional spaces. Does anyone know of any work, published or unpublished, relating to this possible correlation?

  • Samuel Lemos asked a question in Production Systems:
    Does anybody have information about donkey milk production? About their sustainability and production systems?

    I'm making a university paper on production donkeys for the collection of milk and its use as cosmetic products, and also to the use of donkeys as tourism, livestock protection or even as a means to clear the bush. I need information about it and about the sustainability of their production.

  • Kimmo Korhonen added an answer in Linear Regression:
    How do you turn a scatter graph into a linear regression where x becomes Cos2theta instead of time?


    I have no experience with this sort of statistics but hoping to convert some data I've collected into a linear regression so that I can compare mine to some secondary data. 

    The raw data/ scatter graph looks at mean depths of sharks (y axis) over time (x axis). I have this for both the secondary data and mine. 

    In order for me to make a good comparison, I need to transform the hours... the previous work has used cos2theta. 

    Is this something I can do on micrsoft excel? or is there anyother software that can do this? 

    Also as the previous research has looked at depths over 24 hours and mine is only over 9 but shows the same pattern for that time, will this effect the R2  value? 

    I'm trying to learn as much as I can about trig now so any information will be really appreciated!

    I've also created a file (mainly so that I know what I'm trying to do) so I've attached it as t may make more sense to you by seeing the data.

    I know theres a good chance what I'm asking might not work/ sound gibberish but thank you in advance and for reading!


    Kimmo Korhonen · Geological Survey of Finland

    Zoe, what is theta?

  • Nalinda Almeida added an answer in Spectrum:
    Can someone inform me where to find or give me the FTIR spectrum of Al(OH)3?

    Looking for a FTIR spectrum of Al(OH)3?

    Nalinda Almeida · Molded Fiber Glass Research Company, Ashtabula, OH

    Thanks for the information.

  • I would like to know anything about groundwater modelling simulation if anyone does research about this field?

    I think hydro geologist can help me about this research

    Leonard Goeirmanto · Universitas Mercu Buana

    There are many articles in Journal of Hydrology, Science of The Total Environment and Environmental Modelling & Software discussed about how to simulate and make model of groundwater. 

  • Pahlaj Moolio added an answer in FDI:
    Has anyone used the concept of "attractors" to map out FDI flows for a nation?

    Attractors are probably what comes closest to an "equilibrium" for a dynamical system. While the trajectory of the system may vary, its stability may still be captured through an attractor classification. It would be interesting to note certain attractor properties in connection to FDI, and the set of assumptions need to allow for such a scrutiny.

    So far aware of one paper that uses the term "strange attractor" in connection to FDI figuratively. And not in its strictly chaos definition(s).

    Pahlaj Moolio · Pannasastra University of Cambodia

    I have not used attractors.  This is a very interesting question, and I am going to closely follow it. .

  • Hitesh Adhikari added an answer in Potentiostat:
    Can anyone help me to find a specific capacitance of my Sample using Cyclic Voltammetry in GAMRY 1000 Potentiostat?

    Using GAMRY 1000 Potentiostat

    Hitesh Adhikari · The University of Memphis

    Thank you for your response. Actually I used Activated carbon with Alcohal.

  • Luke Norton added an answer in Transfection:
    Can anyone suggest an alternative method over western blot if no good antibody available for a gene ?

    I have transfected tumor cells with pcDNA for a gene of interest. I have tried 5 antibodies for the same gene from different providers, but none of them worked nicely so far. I have mRNA upregulation results from qRT-PCR. Could you suggest an alternative method to show overexpression of that gene at protein level?

    Luke Norton · University of Texas Health Science Center at San Antonio

    If you are over-expressing a gene, and no antibody is available, tag it with a his-tag (or your tag of choice) and use an antibody directed toward the tag to detect your protein of interest. Easy. 

  • Nur Hidayati added an answer in Internal Dosimetry:
    I need internal dosimetry software for nuclear medicne. Can anyone provide me any software, except OLINDA/EXM (it's not available at the moment) ?

    I am interested to purchase an internal dosimetry software for nuclear medicine, but OLINDA/EXM is not available at the moment. Please advise me the similar software which I can use for calculation Internal Dosimetry in Nuclear Medicine?

    Nur Hidayati · Badan Tenaga Nuklir Nasional

    Thank you. I will look for it.

  • How do we manage fisheries in changing ecosystmes?

    How do we understand natural selection of top piscivores?

    Francisco Arreguín-Sánchez · National Polytechnic Institute

    From the stock's point of view you probably could think initially in constant harvesting rates (HR=Catch/Biomass ratio). Is you can define a proper HR for a given stock means that you can catch a proportion of the biomass available each year. If the system change you will always can catch a similar property of the biomass. If, for example, your HR=0.35, when biomass is high you can catch 35% of such biomass and also when biomass is low. Two key points are: 1) define a proper HR accounting not only for survival but also the role of the species in the ecosystem; and 2) identify the proper measures at stock level to avoid overfishing. 

  • Samira Rashetnia added an answer in ArcMap:
    Open .XYZ files in ArcMap 10.1?


    Does any body know how can I open .XYZ files in Arcmap 10.1?

    I have tried the GridBatch Software to convert them to raster but it didn't work as I Guess the files are too heavy (100MB) and there is an error in the processing. 

    Appreciate in advance,


    Samira Rashetnia · Victoria University Melbourne

    Hi Guy,

    Thanks for your answer.I think it will work for my files.

    Kind regards, 

  • Ahmad Sira asked a question in ELISA:
    ELISA assay range?

    When using ELISA, the assay range of the test is that of the dilutions made for the standard. Can we make more standard dilutions to have a wider assay range? or It will be wrong?

  • Simon Cropper added an answer in Mangrove Ecology:
    How can you qualitatively observe and describe juvenile fish communities in mangrove waters, with a non-invasive method?

    Juvenile and young fish communities are stated to be rapidly entering waters among new reforested mangroves. What is the best way to observe and describe sightings qualitatively (via census) ?

    Simon Cropper · University of Melbourne

    Hi Verena,

    I thought of this question when I saw this book... Note you can download a free pdf.

    Cheers Simon

  • Justin P Rodriguez added an answer in Dopamine:
    Why do we measure neurotransmitters in urine and blood serum?

    What is the significance of measuring Neurotransmitters in Blood serum and urine (in vitro) saying real sample analysis?

    If Dopamine gets sulfated enzymatically when it enters the blood, why are we analyzing it in blood serum and urine and comparing it with the free dopamine in the brain? Can we do so? if so why and how?

    I hope that experts in this area can help me.

    Thanks in advance.

    Justin P Rodriguez · Stony Brook University

    To my knowledge, there are no serological tests for Parkinson's disease (PD). You must remember that PD is not a disease of global DA deficiency. Instead, it is caused by a selective loss of a subset of DA neurons (the so called nigrostriatal dopaminergic projection neurons). There are some good hypotheses on why these neurons are susceptible to selective death, but there is not a single reason we know of as to why these particular neurons die in the disease.

    Measuring blood or urine NTs is not an effective method of detecting or screening for the disease. The BBB is pretty effective at keeping NTs separated from the blood other than in a couple of specific regions like the hypothalamus to pituitary venus plexus. On top of this Neural crest cells in the PNS and endocrine system secrete enough catecholamines that any measurement made in serum would overwhelm any contribution made from the CNS.

    Testing for NTs in the serum does have merit when a doctor wants to determine if a patient either has a NT expressing tumor (possibly derived from neural crest cells), or if they want to determine if a patient is surreptitiously taking or not taking a NT increasing drug.

    I hope this makes what I was saying a bit more clear.

  • Why is it important for introducion and utilization of a R&D innovation in Plants?

    The relationship between R&D innovation and economic development is widely acknowledged.Any industry is characterized by more investment in research and development, technical change, and  the output market and the ownership of intellectual properties that support ongoing innovation.

  • Ulf Bonitz added an answer in Graphical Model:
    Are there any studies concerning the usage of graphical models for operational tasks?

    I'am interested in literature / research, which deal (capabilities, advantages, disatvantages) with the use of graphical models for operational tasks, which are traditional are executed with charts and schedules. For instance workforce assignment via drag and drop in a graphic model instead of filling out a table.

    I would be very thankful, if you could share your knowledge in that issue-area, give some literature hints or name the right keywords to search. Thank you!

    Ulf Bonitz · Universität des Saarlandes

    Thank you all very much!, thats very interesting, particularly the wide spectrum of usage.

    This manipulation of data via graphical models (which are usually used to display data) is maybe too ubiquitous in information systems to having an own (named) research-field / keyword? The most suitable topic seems to be "direct manipulation", which is kinda outdated.

    Thank you!

  • Beate Luo added an answer in Teaching Materials:
    Could Chinese schools greatly improve their method of teaching?

    I see what could be 3 ways to improve the method of teaching:

    • Hyperschool new students who have not yet startede school. Research how teachers can hyperschool the material really well for the students to be fast at learning it.
    • Just teach the efficient rote memorization skill. That is, in an early grade, don't allow a student to proceed in hyperschooling until they can memorize a poem during a test that they never saw before one line at a time in such a way that they see the first line on a computer screen and they can press Enter to move onto the next line but can't go back to look at any lines they already moved on from. Doing so will make students waste less time later memorizing things they need to memorize.
    • Teach less material. No need to waste school time teaching students all that material that so few careers require knowledge of instead of those careers teaching it in their training when students don't know what career they will want later. Not teaching that material will give more time to expand on other material, like teaching students to memorize a fast multiplication algorithm and then to apply it mentally.
    Beate Luo · Feng Chia University

    But it is impossible to implement in the settings of the current testing system. Schools need to get their students through the exams and as long as nothing changes there, you can forget about all the good things that work in any other place. They've just changed the entrance exams for senior highs here in Taiwan, with the result that it has become even worse than better.

  • Rosnani Hussin added an answer in Cholecystectomy:
    In elderly patients more than 70 years old, do you recommend laparoscopic or open cholecystectomy?

    In elderly patients more than 70 years old with gall bladder stones, do you recommend laparoscopic or open cholecystectomy?

    Or , no surgery at all except in emergency or profound complaint?

    Rosnani Hussin · Kolej Poly-Tech Mara

    I agree with Andrey

  • To obtain a good thread rolling, which is the minimum necking % in tensile testing of low carbon bar?

    Quality bolts have thread rolling. Is normal use to this bolts steel with 0,2%C alloy with low boron to improve quenchability. The thread rolling is better if the necking obtain in tensile testing is high. Someone know which is the minimun % of necking?

  • Jan Gube added an answer in Cultural Diversity:
    What are some journals on Culture and Diversity?

    What are some journals on Culture and Diversity?

    Jan Gube · University of Tasmania

    Hi Jerri

    You might be able to publish your work here:

    Knowledge Cultures (Very interdisciplinary):

    Culture and Psychology (Has emphasis on cultural psychology approach (and its cognate approaches), but publishes many articles on immigrant or culturally diverse settings):

    Before I recommend further, do you happen to have any specific themes you want to address in your work? Are you working on culture and diversity in a particular field or setting (e.g. education, psychology, social work, law, etc.)? That way, we might be able to recommend targeted and specific ones. 



  • Muhammad Khattab asked a question in Charge Transfer:
    What is the difference between intramolecular charge transfer (ICT), Planar intramolecular charge transfer (PICT), and Twisted (TICT)?

    Also, is it the mechanism of fluorescence?