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

  • Arash Irani added an answer in Fixed Point Theory:
    I am working on "geometry of Banach spaces and applications in metric fixed point theory ". Is anyone interested in collaboration?

    I am working on geometry of banach spces and applications in metric fixed point theory , especially  my interesting is renorming of Banach spaces, Is anyone interested in collaboration

    Arash Irani

    Dear professor JAbdalla Ahmad Tallafha ,

    I am working on "Geometry properties of Banach spaces such as uniformly rotund,
    uniformly smooth and locally uniformly rotund, etc. play a vital
    role in metric fixed point theory"

    A Banach space
    $(X,\|.\|)$ is said to be uniformly convex or
    uniformly rotund (UR) if for all $y_n, x_n \in X$ satisfying
    we have $\displaystyle\lim_{n\to \infty}\|y_n-x_n\|=0,$

    and a Banach space $X$ is said to be locally uniformly rotund (LUR) if for
    all $x, x_n \in X$ satisfying
    we have $\displaystyle\lim_{n\to \infty}\|x-x_n\|=0.$

    The uniformly rotundity and uniformly smoothness are important
    geometric conditions on a Banach space, since geometric conditions
    such as uniformly rotundity and uniformly smoothness are sufficient
    to imply the fixed point property.

    so I am interested in geometry of Banach spaces that imply fixed point property

    "Let $(X, \|.\|)$ be a Banach space and $C$ be a convex closed bounded subset of $X$.
    A mapping $T: C \to C$ is called nonexpansive if for any $x, y \in C$
    we have that $\|Tx - Ty\|\leq\|x - y\|$. $X$ is said to have the
    fixed point property (abbr. FPP) if every nonexpansive mapping
    defined from a closed convex bounded subset into itself has a
    fixed point"

    Any advice and suggestions will be highly appreciated.


  • Shafagat Mahmudova added an answer in Artificial Intelligence:
    What is the future of 'Artificial Intelligence'?

    What are the development in the field of 'Artificial Intelligence'? How far the world is thinking in this context?

    Shafagat Mahmudova

    Dear Chandan Pal,

    Look the link. May be useful.


    Regards, Shafagat

  • Sharad Surnar added an answer in Fisheries Science:
    What is the required protein of siganids/rabbitfish during culture period?

    Being an herbivorous species in nature, I want to know the different protein requirement per life stage of rabbitfish (family Siganidae) for culture purposes.

    Sharad Surnar

    Juvenile stage 30 to 40%

  • Qolamreza Miraki added an answer in Heavy Metal Pollution:
    Can anyone give me any ideas on the limits of exchangeable heavy metals in soil?

    Can anyone give me any ideas what are the limits of exchangeable heavy metals in soil? I want to learn limits of exchangeable heavy metals in soil.

    Qolamreza Miraki

    The main factor to exchange of heavy metals is Soil acidity and pH , this factor control the oxidation and reduction process in Soil. For example when you see the black Soil or black particular in soil it means the oxidation range in low and the soil environment is adapted for reduction there for Fe3+ reduced to Fe2+ ,here we see black color in the soil

  • Pankaj Singh added an answer in Hadoop:
    How can I modify fifo scheduler to run matchmaking algorithm in hadoop YARN?


    I'm trying to modify FIFO and use matchmaking algorithm in Yarn. I setup hadoop on a single node, so ResourceManager, Namenode, and Datanode are all running on the same machine.

    However, after examining the resourcemanager logs, I noticed that some tasks were not local and they are recorded as being assigned to "off switch" node.

    Could you please answer my questions, Aren't all tasks supposed to be local when there is only one datanode and everything is on the same machine?

    Thank you in advance

    Pankaj Singh


    You can can accomplish it using Fair Scheduling. By defualt it's memory but you have the independence to configure the FIFO scheduler. Please check if this link helps else I'll help with detailed information.

    I referred to this when i had to configure the Queue for multi-resources.


    Best Regards,


  • Jacob Y. Stein added an answer in Autobiography:
    I would like to attempt analysing published autobiographies from a phenomenological approach - any literature supporting this?

    Typically, phenomenological approaches, to the best of my limited knowledge, seek out interviewing people and gaining insight as to their lived experiences from their accounts. Is there any literature supporting the choice to analyze published autobiographies from a phenomenological perspective? What are the advantages of such an approach (if any, and given that the disadvantages are self-evident)?


    Jacob Y. Stein

    Please do Allan. Thank you.


  • Kristina Blennow added an answer in Forest:
    Any advice on Hot Spot Analysis and forest presence data?

    Is there anyone who applied the hotspot analysis to forest presence datasets?

    Kristina Blennow

    Dear Sergio,

    You might be interested in a freeware R library that I find works well:


    Kind regards,

    Kristina Blennow

  • Abdul Ilah added an answer in Plant Tissue Culture:
    In Plant Tissue Culture: How can you protect your cultures from Phenolic Compounds, which are released from plant tissues?

    In micropropagation experiments conducted  using Jojoba or other woody plants ; it noticed that the cut of explant was colored to brown, the browning noticed also in the culture medium and the growth was stopped then tissues were died. What is the most suitable method to prevent and solve this problem  ?

    Abdul Ilah

    Frequent sub culturing is best  because in the beginning of first inoculation of the ex plants phenolics used to exude out, I  hope  after two three sub culturing problems will be solved. Try to remove the browned portions from the explant every time.....if the problem is existing you have take care of your hormone concentrations some times if you are using higher concentration of auxin will also damage ex plants making them brown....

  • Arumugam Muthu added an answer in Primer Sequences:
    What is an ideal internal control for real time PCR in Scenedesmus / Chalamydomonas?

    I would like to quantitative the level of expression of gene of my interest, for which i need an internal control for Scenedesmus quardicauda?

    people generaly use 18S ribosomal RNA (18S) or actin for mammalian eukaryotic cells.

    It will be nice if some one share about the ideal gene and its primer sequence for S. quardicauda with published reference.

    Arumugam Muthu

    Many thanks Dr. David Spencer, for providing the exact information which is of in need. As you pointed out it is very logical and relevant to opt two typical candidates’ genes.

    Have a good day..and give like this required information for the needy people.

  • Dimitrios Bompos added an answer in Rubber:
    How can I reduce bouncing of a component in Transient Structural ANSYS Workbench study?

    I am preparing a study for a rubber sheet that is driven horizontally with a constant velocity against a cylindrical surface, where the rubber sheet is loaded with a constant vertical force. My aim is to study the frictional contact between both bodies.

    The solution shows that the rubber sheet bounces up and down (refer to attached snapshot for equivalent stress behavior against study time) during the solution time interval (0.02 seconds), where it gets separated from the cylindrical surface.
    How can I adjust the model settings to have the rubber sheet moving horizontally without going up and down? Please advise.

    NB: I tried to vary stabilization factor in the contact window but that was in vain.

    Dimitrios Bompos

    Is it possible that you face some penetration of the surface and target elements used to model the contact between the cylinder and the sheet? Since there seems to be some kind of a periodic behavior on the graph you have attached, I would check if that periodical behavior is linked with the number of elements you use in the periphery of the cylinder and the length of the sheet.

  • Gilles Horowitz added an answer in Thin Film Transistor:
    What are the physics concepts behind charge transport in organic thin film transistors?

    I read about charge transport models in organic thin film transistors, there are three models as far as I know: VRH, MTR, Polaron. Is there any other models? How are they used to model the OTFT itself?

    Gilles Horowitz

    In agreement with the two previous posts, I would mention as basic concepts drift-diffusion and hopping transport through localised states. To that, I would add percolation. There is an excellent recent review by Sergei Baranovskii here: 

    Nenashev, A. V.; Oelerich, J. O.; Baranovskii, S. D., Theoretical tools for the description of charge transport in disordered organic semiconductors. Journal of physics. Condensed matter (2015) 27 (9), 093201.

  • Ourida Rahal added an answer in Plant DNA Extraction:
    Can anyone point me to a product that replaces the liquid nitrogen in the plant DNA extraction?

    I HAVE a problem to keep this product

    Ourida Rahal

    Salem Mr Gaouar;
    La meilleure façon de garder longtemps les jeunes feuilles d'olivier pour l'extraction d'ADN ultérieure est la conservation dans l'azote liquide.
    Une autre méthode afin de remplacer l’azote liquide: le stockage des jeunes feuilles à - 80°C et  après une lyophilisation puis conserver à -20°C pour l'extraction d'ADN par la suite.

  • Jiří Ambros added an answer in SPSS:
    How can I improve a multiple regression model?

    I am using 10 IVs to design a model for a DV.

    I have initially used the Enter method on SPSS (all ten IVs have been put into the model) and I have an R square value of .65

    I really want to try and improve the correlation coefficient and am considering using a hierarchical method and leave out IVs that do not significantly correlate. 

    I am not sure whether to add the remaining IVs one at a time, in order of their strength of correlation to the first model or quite how to go about doing this.

    I can find lots of texts on how to mechanically conduct the hierarchical model but nothing on the reasoning I should be considering when taking out IVs and putting others in.

    Any advice or direction to the relevant texts would be appreciated.

    Jiří Ambros

    I agree that PCA/FA is a good way to reduce the number of IVs. However the output of these procedures is a "combination" of IVs and it may be sometimes difficult to interpret (if interpretation is something you plan to do in the end).

  • Caner Geyik added an answer in Cell Culture Techniques:
    How do I culture cells with drugs?


    I am planning to design a protocol for culturing the following 2 cell lines with the drug (Gefitinib: 4765 (cell signaling technology). Could you please help me find any specific and detailed protocol how to do it?

    CRL-5908 (NCI-H1975)
    CRL-2868 (HCC827)

    Caner Geyik

    Even I have no experience with IP method, I can suggest a rough protocol.

    1) seed cells to two T-25 flasks and grow them to 70-80% confluency. (I do not know the cell number needed for IP purification, may be even 6-well plates would be enough)

    2) Treat 1 flask with your drug and other with medium or vehicle (for example; if you dissolve your drug in medium containing 0,1%DMSO add  medium containing 0,1%DMSO without drug to your control)

    • incubation time and dose of the drug depends on the cell line you use and the protein of interest, you may need to optimise these variables

    Article below uses same cell lines as you do and you may refer to it for dose&incubation time:

  • Masoud Ovissi added an answer in Magma:
    What is the oldest expectable age from andesite-basalt rocks in oceanic island-arc tectonic setting?

    Dear researchers,

    Given that magmas in oceanic island arc settings originate from mantle wedge as well as subducted oceanic crust (and probably subducted sea floor sediments),  and also regarding the 200 Ma as oldest age for oceanic crust, what is the oldest age we can expect in andesite-basalt rocks erupted in the arc? 

    Masoud Ovissi

    Dear Mohammad Reza,

    As you know, today, the oldest oceanic crust is dated back to less than 200 Ma. But the oldest evidence of oceanic crust is dated back to 3.8 billion years ago (attached link). So it is possible to have some older paleo island arc systems. This is confirmed by finding Tagil paleo island arc system  which is dated back to Late Ordovician- Devonian (attached file).

    Truly Yours,

    Masoud Ovissi

    + 2 more attachments

  • Son Trinh-Van added an answer in HFSS:
    How is a 50 ohm termination declared in HFSS?

    How can we design 50 ohm matched termination for dual port antennas.

    in this case only one antenna is excited at a time and another antenna has to be terminated. 

    Son Trinh-Van

    When simulating antenna with dual (or multi) ports, we always get all S-parameters (or active S11, S22,...). I don't think if have any option in HFSS that can give only S11 when you still simulate dual port antenna.  

  • Suat ŞAHINLER added an answer in Regression Analysis:
    How can I calculate or estimate the interactions of several variables to predict an outcome?

    Sometimes there are lots of variables which are related to predict an outcome and can be considered confounders of each other. So, regression analysis usually help adjust for these variables. 

    The situation will be complicated if 2 or 3 outcomes are related with other and happen together frequently. In this case, how can we accurately and scientifically estimate the interaction of independent and dependent variables?

    How can we find that " which independent variable is the strongest predictor of each outcome?

    thanks for your comments in advance


    I agree with Ira L Cohen, and in addition take care to outocorrelation...

  • Malay Udeshi asked a question in EMU:
    Magnetic moment of NdMnO3 thin films in terms of bohr magneton?

    I am working in NdMnO3 thin films, and recently started studying about the Magnetization in NdMnO3 films

    I had a question about How to calculate Magnetization M in terms of Bohr magneton in case of thin films?

    In case of bulk we can consider the mass of the sample in grams and calculate on the basis of emu/g but in case of thin film as per my knowledge the volume term is considered and the value here will be in emu/cc, this means no mass term present.

    So I have a query of how to calculate the value of magnetic moment for the film in terms of Bohr magneton?

  • Cyril Mechkov added an answer in Electronics and Communication Engineering:
    How do we investigate semiconductor devices in the educational lab?

    This autumn, I have to conduct with students of a new IT specialty a series of lab exercises related to study of basic semiconductor devices: ordinary, zener, light, tunnel and other diodes, bipolar and FET transistors, diode and transistor circuits... So, I temporarily leave the “kingdom” of my favorite analog circuitry where I deal with circuit systems and move to the lower level where I will reveal and show the secrets of circuit components. The problem that stands before me is how to do this in the best way...

    I have unpleasant memories of the way they conducted laboratory exercises in this discipline in the 80's, when I studied in the same university. I remember that I had to perform a series of programmed actions on ready-made laboratory setups enclosed in boxes so their internal structure remained hidden for me...

    That is why, I decided to conduct more interesting laboratory exercises with my students where they can conduct free experiments on flexible prototyping boards by all sorts of components instead of hard prepared experiments on closed laboratory setups. Thus I hope to motivate them by waking their curiosity and creativity.

    My idea is first to pose the problem on the whiteboard, then to find the possible solutions and finally, to implement experiments in various ways. Students can investigate IV curves of diodes and transistors at four levels:

    • manually - driving the circuit by a potentiometer and measuring the electrical quantities by digital multimeters or a digital oscilloscope in XY mode (shown in the first attached picture below)
    • semiautomatically - driving the circuit by a functional generator or simply by a 50 Hz transformer, and measuring the quantities by an analog oscilloscope in XY mode (the second picture)
    • automatically - by a data acquisition board equipped by an appropriate periphery (the third picture)

    It would be interesting for me to know your opinion about such an educational experiment. Whether it would be feasible or would be extremely difficult for students and, as a consequence, for me?

    See also:


    + 3 more attachments

    Cyril Mechkov

    It reminds you of your highschool moments since great ideas are eternal and immortal...There is many philosophy in this setup (if only you can see it:)...

    For example, it is interesting to see why the resistor is connected in the emitter instead the collector... so this stage looks as an amplifier with emitter degeneration...

  • Antonios Georgantzoglou added an answer in Image Segmentation:
    Can anyone recommend me some good techniques of food image segmentation?

    I want to segment a food image. Lets say there are three fruits (i.e. an apple, an orange, a banana) kept in a plate. i want to separate these fruits from image.

  • Sheerien Rajput asked a question in Sorting:
    Is estimation of viral titre an unavoidable step in Transduction experiments?

    I have been working with 3rd generation lentiviral vectors. The problem is that the transduction efficiency is very low and GFP signal is expressed atleast after 72 hours (although the expression is under the control of CMV promoter). 

    And in this duration normally cells take atleast 2 divisions and then the population for sorting becomes more difficult to analyze and sort through FACS.

    Is there anyother way to select transduced cells or I can start with low cell density and high viral load without doing titre and then sort them through FACS. Any suggestions please.

  • Naga Venkateswara Rao Nulakani added an answer in Tight Binding:
    Can any one suggest me the best packages or codes to perform tight binding calculations for graphene like materials ?

    I want  user friendly codes or packages for tight binding calcualtiuons of graphene like materials

    Naga Venkateswara Rao Nulakani

    Thanks for all for your kind suggestions

  • Cherry Stewart added an answer in Actor Network Theory:
    Are you with or against proposing a new learning theory?

    Several years ago, I ran a debate with one of my professors at Education Department about human working memory. He insisted that technology has ruined human memory; many people rely more and more on their mobiles and laptops instead of their own memories. He also presented some research evidence showing that.
    At that time, it was hard for me to accept this idea. I argued that human is a clever being. If tools or technologies would help us to save our memories, then is it logical to kick these technologies out or even reduce our usage of them because they harm our memories? However, my opinion was not supported by a solid theory. Cognitivism and Constructivism clearly state that our inner memories are important in a learning process.

    This debate has carved in my mind and the case was not closed, at least for me. Recently, we have investigated some of new learning theories. Among a long list, we visited Actor-Network Theory, Community of Practice, and Connectivism. And to be honest, I found Connectivism wide enough to answer my question and to build upon. Knowledge is a network and learning is a process of finding patterns reside in this network. Inside or outside human skull, it does not matter.

    This is not to end the discussion; actually, it is to open it. Are you with or against of proposing new learning theory? Our understanding of knowledge network, learning and Connectivism presented in this paper.

    Cherry Stewart

    Thank you for your suggestions. I'm sure we can share information at a later date. Like you I am inundated with other activities at this time of year. I am working on two papers in this area myself. May I send to you for review when I get together?

  • Soon Li Lee added an answer in Reward:
    How Do You Empirically/Scientifically Determine The Number of Moderator Variables to Include in a Research/Model?

    Hi RGaters,

    Thanks to everyone who contributed to my question on the difference between internal/external rewards and intrinsic/extrinsic rewards.

    Are there references on how/ways to determine (empirically/mathematically) the number of moderators to include in a management research? Is there a reasonable limit to the number of moderators to include in a model? I presume there is. How does a researcher objectively determine this limit? Or is the number of moderators included in a model subjectively determined.

    For example, there is a paper on control variable use in management research by Antic et al. (2011) which explains best practices for control variable use and reporting. Is there a reference on best practice on moderator variables use? Are there articles recommending best practices on moderator use and determining the number of moderators to include in a model or management research? 

    This question is not about understanding moderating effects as the answer to this question has already been provided by MacKinnon and colleagues (e.g. MacKinnon, 2011; Fairchild and MacKinnon, 2009), and several other researchers. I need to be able to scientifically support and justify the number moderators I decide to include in my model.


    Atinc, G., Simmering, M. J., & Kroll, M. J. (2011). Control variable use and reporting in macro and micro management research. Organizational Research Methods, 1094428110397773.

    Soon Li Lee

    I am not sure if there is any but I think the appropriate number of moderators is dependent on your research question or research aim. Perhaps you should justify the importance of assessing the moderators in your study. 

  • Paul Glad Mihai added an answer in Dyslexia:
    Which consonants do dyslexics have most trouble with?

    I'm looking for literature on dyslexics troubles with consonants. I found this one http://www.sciencedirect.com/science/article/pii/0010027795006974 that found that dyslexics confused /t∫a/ with /∫a/ and /pa/ with /fa/ significantly more than did controls.

    Does anybody know of any others?

    Paul Glad Mihai

    Thanks, that's very helpful.

  • Florian Arun Täube added an answer in Innovation Studies:
    Are there in developed countries models of cooperation between large and small firms?

    I am studying the models of cooperation and relationship between NTBFs or SMEs and large companies (supply chain, R&D or ….). I would appreciate if you could help me, Are there in developed countries program, plan or act about support of formation this relationships?

    Florian Arun Täube

    I think Wim Vanhaverbeke has done some work on this in the context of Open Innovation.

    Apart from the literature, there are lots of initiatives recently (in Germany) called Corporate meets Entrepreneur, Corporate Startup Summit etc... The idea behind these is to learn from each other.

  • Amol Chintaman Badgujar added an answer in Thin Films:
    Measuring thickness of thin film using Atomic Force Microscope (AFM)??

    How to measure thickness of thin film using AFM?

    I have see some people have determined thickness of thin film using AFM.

    I have also tried but found that thickness is changing with changing the scanning area.

    eg. the thickness is 13 nm for 500*500 nm^2 and around 27 for 1000*1000 nm^2

    could someone elaborate it?

    are there any other methods to measure the thickness of MBE grown thin film?

    Thank you in advance !

    Amol Chintaman Badgujar

    Mr. Vikas,

    One way to measure thickness of thin films can be AFM measurement on step created on thin film. Step could be obtained by wet itching or any other suitable way depending on type of material coated and deposition technique. You need to take readings on stepped region. Difference in two readings can give thickness values. 

    And as per as scanning area is concerned you need to decide based on equipment capabilities to give accurate values. You may do it by taking reference thin films with known thickness and calibrate your readings.

  • Martin Baeker added an answer in Abaqus:
    Why the result is different between abaqus standard and abaqus explicit?

    Hi all, 

    I run two simple simulations in standard and explicit based on the same FE model. The model is showed below. There are three parts in the model. One is a deformable body and others are treated as rigid body. Two rigid bodies are linked by a spring which stiffness was 720N/mm. The deformable part is controlled by displacement. The total displacement is 5 mm. Usually, the force applied on the deformable part should equal the spring force. I get a good result from Abaqus/standard. However, when I run the same model in Abaqus/explicit, the result is weird. 

    How could I solve this problem?


    + 3 more attachments

    Martin Baeker

    Your explicit simulation is dynamic, i.e. it takes inertia into account, This implies that elastic waves will travel through your structure. In a FE-simulation, these will not be damped unless you add damping to your material data or add a dashpot element or some other viscous effect.

    IIUC, your problem itself is basically time-independent. In the explicit simulation, you will see a time dependence due to the final propagation speed of elastic waves.

    You can reduce the effects of these waves by using mass scaling (see the manual for this).

  • Carla F Marchetti added an answer in Calcium Image:
    Has anyone observed an increase in FURA2 emission at 510nm with both 340 and 380nm excitation?

    Actually, we are trying to install a calcium imaging station. During trial runs we are noticing that upon Thapsigargin application on cells (multiple cell lines have been tested) FURA2 emission is increasing at both 340 and 380nM excitation. It is weird as emission at 380 should decrease along with simultaneous increase at 340nM. We are using Lambda DG4 for fast excitation switch and FURA2 filters are from Chroma. DG4 and filters appear to be working fine. What could be the possibilities behind this weird observation? Any help/suggestion in this regard will be highly appreciated.



    Carla F Marchetti

    I suppose you load your cells with Fura-2AM. This should be dissolved in anhydrous DMSO. I have been used this method for many years and according to my experience, when both signals change in the same direction, it is simply not Ca signal, but some other (auto)fluorescence signal intefering with your measurements. How do you prepare thapsigargin? Also, I would run a calibration with ionomycin and see how your loaded cell behave and how much of your signal is Ca-dependent..

  • Jarosław Króliczewski added an answer in SF9:
    How I can improve the extraction efficiency of membrane proteins?

    Hello, I am working with membrane proteins expressed in Sf9 cells. My protein is fused to mRuby2 red fluorescent protein for FSEC purposes, but it seems that it doesn't extract efficiently from the membrane with any of the detergents tested so far (doesn't extract at all with non anionic detergents such as DDM, extracts/solubilizes a little with zwitterionic Fos cholines). I work with above CMC values for all detergents. The protein is clearly localized in the membrane since the purified insect cell membranes are pink after visual inspection. Does anybody have similar experience and could give me some advice on how to proceed? I am working with the full length protein, harboring the extracellular, transmembrane and cytoplasmic domains. I haven't tried multiple constructs with truncated regions yet, since I would prefer to work with the full length wild type protein rather than with truncated constructs. Moreover, my final purpose is not to crystallize the protein, but rather produce it in sufficient amounts for biochemical and biophysical characterization.

    Jarosław Króliczewski

    You can read our paper at