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

  • Rahimi Ali added an answer in Applied Linguistics:
    Does anyone have updates from the 'Interactionist theory'?
    I am doing a dissertation about the interaction between EFL learners and English speakers, but I am still struggling with the specific thesis topic. There are a lot of key words and concepts flowing to my head. Interactionist perspective is of course one of them. Who are the keen theorists in the field? Where to start reading? Thanks for your suggestion.
    Rahimi Ali · Bangkok University


    here are the publications:




  • Ian J Slipper added an answer in Cement:
    Ritveld method on a hydrated cement: what are the limit values of crystal size ? what is the order to follow during the refinement ?

    I'm doing some rietveld anylyses on hydrated cement in order to quantify the phases. I've realized that it is not very repeatable and the results you get depend on the order you follow to refine the crystal parametres. I want to now what is the best order one have to follow to refine the parameters. 
    I also need some references containing the limits values of crystal size and crystal strain. 

    Ian J Slipper · University of Greenwich

    You can just enter a value in the maximum box if it is blank.

    If you can post the .inp file and the .raw file then we can have a look for you.

  • Gerald Dörflinger added an answer in Hydrologic and Water Resource Modeling and Simulation:
    Is there any mathematical method that I can use to convert 30 meter resolution DEM to 10 Meter?

    Actually I need 10 meter cross sections but 30 meter resolution DEM is not appropriate. Actually in my study area, the river width is 10 to 20 meter so If I use 30 meter resolution DEM for the cross sections so only one value will come.

    Thus I want to convert it into 10 meter resolution. Though it wont be that much accurate, I accept it.

    Gerald Dörflinger · Ministry of Agriculture, Natural Resources and Environment

    River flood modeling for a 10m wide river, based on a 30m DEM only sounds not good to me. There will be no reliability in your results. I agree with Michael, try to get hold of some cross section data - it is only a 10m wide river, it should not be difficult to measure them.

  • Stefan Wenzel added an answer in Roman Archaeology:
    Does anyone know nailed horseshoes from a well documented Roman context?


    I'm interested in literature about nailed horse shoes (not hipposandals) from well documented Roman contexts.

    The existence of nailed horseshoes has been denied recently by

    Simone Martini, Mittelalterliche und neuzeitliche Hufeisen im Rheinischen Landesmuseum Trier. Funde und Ausgrabungen im Bezirk Trier 42, 2010, 70-90.

    According to

    Insa Lingens, Die Entwicklung der Hufpflege und des Hufbeschlags von der Antike bis zur Neuzeit unter besonderer Berücksichtigung des Hufbeschlags bei der Hufrehe (PhD thesis, Berlin 2008).



    there is no clear evidence for nailed horseshoes from Roman times.

    Currently I'm working on artefacts excavated the 60ies near Obermendig (Rhineland-Palatinate, Germany) in a late Roman granary (horreum) presumably fortified as a burgus. 99% of these finds date to the 4th and 5th centuries AD, but there are some few late medieval objects from the site. There are two horseshoes among the finds. May they be Roman? Any advice would be welcome.

    Best regards,

    Stefan Wenzel

    PS: Please find drawings of the horseshoes attached.

    Stefan Wenzel · Römisch-Germanisches Zentralmuseum - Archaeological research institute

    There is a paper dealing with horse burials of Roman times in a cementary in  the Netherlands, but no horseshoes seem to have been found:

    R. C. G. M. Lauwerier &.W.A.M. Hessing, Men, horses and the Miss Blanche effect; Roman horse burials in a cemetery at Kesteren, the Netherlands. Helinium, XXXII/1-2, 1992, pp. 78-109.

    However the paper gives an overview of Roman horse burials in the Northwestern provinces.

    Best regards,


  • Syanda Mtolo asked a question in Writing:
    What is Southern blight?

    I am writing a literature on Southern blight..

    Where should I start with my review..

  • Adil Hussain added an answer in dsRNA:
    Can any one explain me how to deliver dsRNA to plant system using nano particles?

    What will be the best way to deliver the dsRNA to plants? What will the formulation used? 

    Adil Hussain · International Islamic University, Islamabad

    Li Jiang et al suggests, that A cationic fluorescence nanoparticle delivery system is best way to deliver dsRNA in to plants because it efficiently enters plants with high transfection efficacy. By Applying a mixture of G2/dsRNA to the model plant, Arabidopsis root, leads to significant reduction in the expression of important developmental genes and results in apparent phenotypes.

    read the attached article this might clear your question... :)

  • Fuad Bahram added an answer in Necrosis:
    What is difference between apoptosis and necrosis?

    difference between apoptosis and necrosis

    Fuad Bahram

    To answer your question, here is just a generally differences:

    Apoptosis (programmed cell death), is a form of cell death that is generally initiated by normal processes. While, Necrosis is (unprogrammed) the premature death of cells. Caused by external factors to the cell or tissue, such as inflammation, infection, or toxins.

    Normally, apoptosis has no noticeable symptoms related to the process. Except when the process cause too many cell deaths or cause too few. Many autoimmune diseases, such as muscular dystrophy and also Alzheimer, are believed to be related to excessive apoptosis, causing muscle or nerve cells to die to early. In cancer, the cells grows without any control, and the apoptotic process are disrupted (too few cell death) therefore many cancer drugs have a strategy to enhance the apoptotic machinery.

    In contrast, necrosis is an uncontrolled change in an organism's cell balance, so it is always harmful, resulting in noticeable, negative symptoms. These reactions are often accompanied by a metabolic boost and fever, which can lead to fatigue and an overall weakened immune system.

    To go forward and clarify the differences in molecular and protein level that could take much longer time but shortly, I can say that there are 100s of different protein are involved in the process and there are absolutely differences in the mechanisms which are regulation both unprogrammed and programmed cell death.

  • Dirk De Meyere added an answer in Plant Taxonomy:
    Does anybody know the name of this plant ?

    I need a common name or scientific name   or group to which it belongs


    Dirk De Meyere · Agentschap Plantentuin Meise

    Hi, no doubt it's an Arisaema species (Araceae) close to A. taiwanense etc

  • Ioannis Kleftogiannis added an answer in Graphene Nanoribbon:
    What is an analytical expression for the ZZ graphene edge state?

    Sci. Technol. Adv. Mater. 11 (2010) 054504 and J. Appl. Phys. 111, 074318 (2012) provide a derivation for the spectrum of graphene nanoribbons on a tight binding basis. I have been trying to understand the edge state based on these articles but hit a bit of a road block.

    When plotting the band structure as derived in the articles (see attached image) the bulk states (blue) come out very nicely, but the edge state (red) invariably ends up being a mess and nowhere near what it should be.

    Does anyone know other good resources for a derivation of the flat band or can explain it to me based on the articles above?

    Ioannis Kleftogiannis · National Chiao Tung University

    You can reproduce numerically the band structure of zig-zag nanoribbons relatively easy as follows. First you have to build the Hamiltonian of each unit cell say H0 being a single linear chain for the zig-zag nanoribbon. Then you can build the Hamiltonian representing connections between the unit cells say, H01. After that you have to diagonalize H0+H01*exp(ik)+H10*exp(-ik) (Bloch's theorem) and plot the eigenvalues for every k. If everything is done correctly you should be able to reproduce the flat bands along with the rest of the band structure. Hope this helps, although it's not the analytical derivation you are seeking. 

  • Prasun Ghosal asked a question in Universe:
    Paradox between the age and size of the Universe...age is 13.82 bn years but the size of observable Universe is around 91 bn LY. Why this anomaly?

    In 2012, WMAP estimated the age of the universe to be 13.772 billion years, with an uncertainty of 59 million years. In 2013, Planck measured the age of the universe at 13.82 billion years.

    Keeping this fact in mind and considering the speed of light, the size of visible Universe should be around 13.82 billion light years (considering Big Bang theory). But in reality, the observable universe is about 28 billion parsecs (91 billion light-years) in diameter at the present time. The size of the whole Universe is not known and may be infinite.

    Is there any anomaly? Or what is the theory/explanation behind? Is it in conformity with the laws of Physics?

  • Zeinab Abde added an answer in Gaussian (Software):
    Can anyone help with an error termination about Gaussian 09 calculation?

    I am trying to find out the structure of a transition state
    for a decomposition reaction (HXeXeF→HXeF+Xe) by using QST3 and I get the following error:
    Inconsistency: ModMin= 2 Eigenvalue= 1.54137914D-03.
    Error termination via Lnk1e in /usr/share/apps/g09/l103.exe

    Does anyone have an idea of what this means and how to solve it?

    Zeinab Abde · Shahid Chamran University of Ahvaz

    Dear all, thank you for your responds.

  • Daniel Cozzolino added an answer in Trace Analysis:
    Why is NIR not good for trace analysis?

    Why NIR-Spectroscopy is not a good trace analysis?

    Thank you in advance

    Daniel Cozzolino · University of Adelaide

    In the NIR, mostly organic compounds are measured. Some metals and/or minerals can be measured but if they are associated with organic matter or organic compounds. In addition, the limit of detection of the NIR make it not adequate to predict trace compounds.  Haven said that, some surrogate calibrations can be used, but they can be highly dependant on the matrix and are not universally applicable.

  • Bhaarathy Velmurugan added an answer in Autofluorescence:
    Does Anti-fading media (DMEM+Rutin) for Live cell imaging help to remove autofluorescence?

    Can you suggest a suitable media for live cell imaging of GFP/pdendra in fibroblast

    Bhaarathy Velmurugan · Nanyang Technological University

    Thanks for the reply. I am planning for a live cell imaging continuous for more than 6 hours. So, that brought in a little concern ;)

  • Sambhudutta Nanda added an answer in HFSS:
    What is the basic formula for calculation of the Airbox dimension during the simulation of any antenna structure in HFSS ?

    Could any one please inform which formula should I use for the calculation of the airbox dimension and What happens if the dimension varies ?

    Sambhudutta Nanda · National Institute of Technology Rourkela

    generaly it should be greater than lambda/4

  • Girijesh Mathur added an answer in QuaSy:
    Can somebody guide me as to how to deal with numerical analysis of flow field near contact discontinuity?

    I am analyzing a quasi one dimensional supersonic flow field using Method of Characteristics.The medium is air. I am implementing Method of Characteristics numerically in the regions of continuous flow and jump conditions at discontinuities. Time step used is 7.5e-06 sec. During the simulation, I find that the solution becomes highly oscillatory and blows up in the regions adjoining contact discontinuity.

    Girijesh Mathur · Indian Institute of Technology Kanpur

    Thanks Vikash. I am presently looking at some methods to smooth out the discontinuity gradually over many time steps. I have tried out bigger time step. But the scheme becomes highly unstable. I will look at other aspects as suggested by you.

  • Stanislaw Flaga added an answer in PLC:
    How do I implement a pid in ladder diagram on fx-3g mitsubishi plc?

    to all plc progrmmer

    Stanislaw Flaga · AGH University of Science and Technology in Kraków

     Look at the page http://pcc.imir.agh.edu.pl/poz18/ (in Polish).

  • Parth Sarathi Mahapatra added an answer in Indoor Air Pollution:
    What are adequate instruments for measuring Indoor Air Pollution in India (CO and PM2.5) for the combustion of biomass?

    We would like to measure Indoor Air Pollution, in particular CO and PM 2.5, in rural, poorly ventilated kitchens during the preparation of meals

    Do you know any measuring devices that would be suitable for our purpose and that are sensitive enough to capture pollution also during that short period of time? Can you recommend CO dataloggers? Or would you rather recommend CO diffusion tubes?

    Also, do you know a low-cost instrument for measuring PM that is easy to handle? As far as I know they are all quite expensive.

    Parth Sarathi Mahapatra · Institute of Minerals and Materials Technology

    I believe a GRIMM Aerosol Spectrometer instrument will solve your purpose for PM1, 2.5 and 10 and regarding CO you can look for instruments from Horiba/Thermo.

    All the best!

  • Rahimi Ali added an answer in Cross-Cultural Comparison:
    What are cross-cultural differences in terms of assessment and evaluation practices in educational settings?

    cultural differences with respect to evaluation and testing.

    Rahimi Ali · Bangkok University

    thanks for enlightening elaboration  , Daniela,  I also believe washback effect is strong , so too are political trends

  • G. G. J. Ernst asked a question in Lightning Detection:
    Has anyone ever tried to detect Blue Jets, Elves and Sprites above Volcanic Eruption Clouds ?

    Many years back, I attended a special session on Elves, Sprites and Blue Jets at AGU in San Francisco.

    These are typically observed above severe thunderstorm clouds and are observed at something like 100km altitude (magnetosphere).

    Explosive volcanic eruptions often occur through a lake or the sea (eg. Rose et al 1995), and can also entrain 100-1000s MTons of water vapour from the boundary layer for atmospheric moisture when extensive pyroclastic density currents are generated and source the ashcloud (eg. 15 June 1991 Pinatubo; Dartevelle et al 2002) .

    All such eruptions are rich in water vapour.

    Rapidly during ash cloud ascent water vapour condenses on ash particles.

    Then freeze over to form snowflakes and ice particles (eg. Rabaul 1937, Surtsey 1963, Pinatubo 1991, Vulcan 1994, Montserrat Boxing Day cloud, Hekla 2000, Eyjafjallajokull 2010...; eg. Durant et al 2008 and refs therein) .

    In this way, the eruption cloud turns into some kind of severe thunderstorm or generates one, whichever way one wishes to look at it.

    Meteorological severe storms generate electricity.

    One can expect that severe storms associated with volcanic explosive eruptions will generate electricty using the same electrification mechanisms as your standard thunderstorm.

    In addition to those electrification mechanisms associated with normal thunderstorms, however, when magma is fragmented into ash, additional electrification occurs during explosive volcanic eruptions and especially in phreatomagmatic éruptions as a result of fracto-emission (Gilbert and Lane 1994, etc...). 

    Electrification (charge generation, charge separation and "dipole" system development)  from fracto-emission is consistent with field measurements of the electric field during volcanic explosive éruptions (eg. Sakurajima; Gilbert et al 1992) and with lightning detection during explosive eruptions.

    Explosive volcanic eruptions commonly reach ascent heights that are similar or higher than severe thunderstorms, exceeding 15-20km elevation above the ground. Indeed numerous VEI 3 eruption clouds are detected by remote sensing colleagues each year (eg. Rose et al 2000).

    Hence, with similar thermal energy fluxes (correlated with ascent height) and expected more intense electrification than severe thunderstorms, phreato-subplinian or phreatoplinian explosive eruptions can be expected to generate phenomena such as elves, blue jets and sprites into the magnetosphere directly above the volcanic eruption cloud.

    But I am not aware of anyone who would have made any measurements to assess this hypothesis in the atmospheric science community?

    I am curious to find out if anyone knows more about this since I first queried atmospheric experts on elves, sprites and blue jets above standard thunderstorms more than 20 years back ?



  • Somchoke Kittisakulnam asked a question in Buffer:
    The buffer (pH 4.5) represented the lactic acid containing food solution, which kind of buffer needed?

    I would like to simulate the liquid media used for releasing test of my encapsulated particles. The prospective system is the lactic acid fermented food products. Which kind of buffer (which have to contain the lactic acid and at pH 4.5) is preferred?

    If I use the other buffer systems like citrate-phosphate or citrate-sodium citrate buffers and add lactic acid into these buffers, does it represent the lactic acid containing-food liquid? or should I use lactic acid-sodium lactate buffer instead of them? Which one is the best represented lactic acid-containing food liquid system?

  • Daniel Cozzolino added an answer in alpha-Amylases:
    Which is the best method to analyse alpha-amylase activity in cereals?

    Which would you suggest as analytical method to assess alpha-amylase activity from cereal grains, using small amounts of sample?

    For me, "best" means with the minimum possible error, and also (possibly) high rapidity of the analysis.


    Daniel Cozzolino · University of Adelaide

    To Martina

    Please check the Perten web site. They have some application notes.  I can sned some of my papers in the topic. Happy to help.

  • Susan Parker added an answer in Analog Electronics:
    How does the Impedance analyzer work? if Device Under Test (DUT) is 1 Mohm, is it possible to measure impedance passing current 1 mA?

    I have doubt on working principle principle of Impedance Analyzer?

    If 1 mA current is passed on DUT (1 Mohm) and Impedance is measured by sweeping the frequency. Then voltage drop across DUT is 1 mA * 1 Mohm,i think it is not possible?How impedance analyzer measures highly resistive component   in constant current mode?

    Susan Parker · Imperial College London

    Impedance is AC, resistance is DC.

    Given that everything has inductance at AC, the impedance will vary with frequency.

    However this inductance may be very small, so many not figure in your calculations.

    Note also though that many types of resistors are made with a spiral based resistive element, which means that it will in effect be an air core inductor with a resistive R i.e. DC and impedance Z (i.e. AC) parts.

    In normal use impedance can never be lower than the DC resistance, so a part will have a flat line from DC to some value of AC, then start to rise as the inductive part overrides the resistance. Note that this will depend on a number of factors including the impedance of the source driving the part.  

    Finally ALL components have lead, and for chips bond wire, inductance. Perusing any detailed component data sheets should give you these figures.

    This is why RF design becomes trickier to do, as all these "parasitic" effects start to come into play as the frequencies increase.

    I would also note that 1mA at 1M ohm is 1000 volts, so I would advise caution when testing as these voltages are potentially lethal.

    See link for basic and handy calculator.

  • Parth Sarathi Mahapatra added an answer in Atmospheric Sciences:
    Where can I get archived and present time Mixing height data set for Indian cities?

    working over pollutants load dispersion over Delhi city.

    Parth Sarathi Mahapatra · Institute of Minerals and Materials Technology

    If not cities exactly, you can also download it over a grid of desired size encompassing the city required. You can get this from MACC Reanalysis data website.


    Hope it helps!

  • Laurent Bruxelles added an answer in Geomorphology:
    Does karren or lapiaz exist on non-calcareous rocks?
    Does karren or lapiaz exist on non-calcareous rocks?
    Laurent Bruxelles · Institut national de recherches archéologiques préventives

    Hi Juan,

    But cryptocorrosion also takes advantage of the rock structure. Of course, subaerial corrosion exists, no problem. But it's just to said that we have also to remind that these features can be part of the heritage, when the rocks were covered by soil or another cover. It's not well known but it is the case of most of them in limestones or dolomite in temperate or tropical area, if the slope is not too steepy of course.


  • Daniel Cozzolino added an answer in Traumatic Vascular Injury:
    How do I assess the quality of a NIRS device?

    I'm doing pre/post measurements in the upper limbs during controlled exposure of human subjects.   After that, I'd really like to take the device and run around the hospital with it (assuming ethics approval of course).  I don't think I need a very sensitive device, just something durable and reliable.  

    Two questions: 

    • How do I assess the literature comparing NIRS devices? 
    • How much can I expect to spend? 

    Does anyone have any recommendations? I liked the look of this device 

    -Van Haren, R. M., Ryan, M. L., Thorson, C. M., Namias, N., Livingstone, A. S., & Proctor, K. G. (2013). Bilateral near-infrared spectroscopy for detecting traumatic vascular injury. journal of surgical research, 184(1), 526-532. link

    Or the Artinis Portamon but that seems more like a Lexus :)


    Daniel Cozzolino · University of Adelaide


    The simple answer is depends on what type of measurements or what do you want to measure.

    There are several portable instruments, NIR and MIR, different wavelength ranges, etc. Prices can vary from few thousand American dollars up to 120K.

    Portable no necessary means handheld. There are some bench instruments attached with fiber optics  that can be mounted in a trolley and can be portable. These instruments usually are FT-NIR. On the other hand you can have handheld instruments.

  • Christian Q. Scheckhuber added an answer in Mitochondrial Dynamics:
    What is the consequence of DRP1 phosphorylation on mitochondrial dynamics?

    Reading literature about mitochondria fission/fusion mechanism I came across two oposite explanations on role of phosphorylation of DRP1 in regulation of mitofission. Study of Han and colleagues 2008 reports increase in fission with increase of DRP1 phosphorylation, while two other papers: Chang and Blackstone 2007 an Cribbs and Strack 2007- observe an oposite situation: phosphorylation of DRP1 (at same residue as in Han experiment) causes inhibition of fission. 

    I do not have any experience in this field and would like to know whether there is any consensual mechanism worked out. Thank you in advance for your insights.

    Christian Q. Scheckhuber · Senckenberg Research Institute

    Interesting question. Wang et al. (http://www.ncbi.nlm.nih.gov/pubmed/22326220) looked into the different findings on the contribution of Drp1 S600 phosphorylation (corresponding to S637 in human Drp1 isoform 1) to mitochondrial dynamics. They conclude: "Our interpretation of these seemingly contradictory observations is that the functional consequences of serine phosphorylation of Drp1 could be highly cell-type and/or stimulus dependent."

    I am looking forward to see more studies addressing the role of Drp1 S600 phosphorylation on mitochondrial fission regulation.

    Cheers, Christian

  • António Manuel Abreu Freire Diogo added an answer in Wastewater Management:
    In municipal wastewater treatment, there is currently a clear delimitation between secondary and tertiary treatment?

    What basic treatment operations can be considered in each one?

    Traditionally, primary and secondary biologic treatment included normally separation of settable solids and reduction of suspended solids and organic load, measured through Biochemical Oxygen Demand, BOD (and Chemical Oxygen Demand, COD), and tertiary treatment included mainly removal of nutrients and sometimes filtration and disinfection. With the development of the treatment processes what are the current trends?

    António Manuel Abreu Freire Diogo · University of Coimbra

    Dear Nizar: You are correct, as always, even if the aspects that you mention are a little far from the main question that I would like to discuss here. In fact, Wastewater Treatment Plants (WWTPs) are (should be) normally installed sufficiently far from the center of the urban agglomerates, and the predominant local winds should also be considered in the place selected for the WWTPs. Hydrogen sulfide control have been traditionally a major concern of sewerage systems management since the first combined systems in century XIX. Hydrogen sulfide (H2S) is a gas characterized by an intense bad odor (similar to the smell of rotten eggs) and is a poison gas that, depending of its concentration in atmospheric air and time of human exposition, may even kill. It may result from the anaerobic decomposition of the organic matter in the sewerage systems in the absence of a suitable concentration of dissolved oxygen. Large systems, hot temperatures and pipe flow are critical aspects in the conception, design and operation of the systems. There are well regulated rules all over the world and good engineering practices and procedures for controlling sulfide generation and its effects since a long time ago. Even if “small is beautiful”, my preference is clearly for large regional sanitary sewerage systems working properly, which may allow important economy scales and a better control of the environmental aspects. 

  • Ananya Mukherjee asked a question in Flavones:
    Is there any way to contract the multiplication of two triplets from a discrete symmetry groups like A_4 , to a triplet and a singlet at a time?

    Can we contract the multiplication of two triplets of the group S_4 as

    1. (3_1 *3_1 ) contracted to a triplet (3_1) and multiplied by a triplet flavon (3_1) to get in turn (3_1 *3_1 ~ 3_1 * 3_1 (flavon) ~ 1) 

    2.  (3_1 *3_1 ) to a singlet 1 and multiplied by the same triplet flavon (3_1)

    to get in turn (3_1 *3_1 ~ 1 * 3_1 (flavon) ~ 1)

    at a time and with the same flavon VEV which is going to break the S_4 symmetry at a perticular scale??

    N.B : finally to be contracted to the singlet representation "1"  as the terms in the corresponding lagrangian should be singlet in nature.

  • Jordi Busquet Duran added an answer in Pierre Bourdieu:
    What are at present the main features of the 'journalistic field' given the consciousness of the digital revolution?

    I am doing research on the subject. I know Pierre Bourdieu's work on television, however it is possible that later some authors have applied the notion of Bourdieu field for studying the media field.

    Jordi Busquet Duran · Universitat Ramon Llull

    Ok. No problem.