Q&A

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

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
  • Mohammad N. Elnesr added an answer in Soil Moisture:
    What is the cheapest and easiest way to obtain periodic soil moisture measurements up to 10m depth without digging big soil pits?

    I want to estimate the soil moisture across several plots at one meter interval upto 10 m depth. Any good references are also welcome.

    Mohammad N. Elnesr · King Saud University

    Due to the depth you specified, many of the normal devices will not fit.  I think it is possible to install a TDR probe at each depth.

    Additionally, I highly recommend that you read the attached reference to compare all the soil-moisture measuring methods, technologies, and devices. Through It, you will be an expert for selecting the appropriate method/device for any case.

  • Is fishing mortality inversely proportional to mortality of the fishermen?

    Stock assessment  and management of fishable marine resources are ultimately based on fishing mortality. If the populations of fishable marine resources appear overexploited, the solution generally recommended to policy makers is to reduce fishing effort. Wisely, many policy makers take into account the mortality of the fishermen through measures such as "loss of income" etc .. Unfortunately policymakers, pressed by the fishermen’s lobby, often excessively favour the fishermen in fear of losing support.

    Trevor John Kenchington · Gadus Associates

    Leonardo, I think you are approaching important questions that go to the heart of the failure of conventional fisheries management but you are over simplifying -- perhaps deliberately, as you make your point.

    It is not, of course, necessary for fishermen to die in order to reduce fishing mortality. Even non-human predators can switch their prey resources to some extent and fishermen can shift between fisheries, emigrate to fish new regions of the ocean or even leave the sea to work ashore. The converse is part of the problem: Whenever a resource recovers, there are many fishermen and potential fishermen waiting to enter the newly-prosperous fishery. Such complexities of human behaviour are what make attempts to model human/fish interactions in terms of predator/prey relationships futile: Fishermen are only the "tentacles" by which the human "super organism" obtains its fish. Consumers are the "stomach" and the demography of the consuming populations operates through their economic relations with food harvesters of all kinds to determine the pressures placed on food sources -- agricultural soils as much as seafood resources. Most of those same consumers are also parts of the "super organism's" "brain", influencing the "tentacles" through politics and regulation. That system can be modeled but models which capture the behaviour of the system are likely to be far more complicated than ecologists' predator-prey equations.

    I think the solution to the conundrum that you have raised is quite different: To frame the issue in terms of excessive fishing mortality, reductions in effort and the tempering of such reductions through concerns over fishermen's interests is to perpetuate the idea that fisheries management is a conflict between fish conservation and fishermen. That has been the experience of managing offshore fisheries for the past 150 years or so but it was not the basis for the management of near-shore fisheries over the previous 100,000 (or maybe 1,000,000). I think we need a recognition that fisheries management is a matter of balance, not conflict: Take no fish this year and you do not have a fishery. Take too many this year and you will soon not have a fishery. Take an intermediate amount and you have the basis for lasting prosperity, balancing the taking with the leaving. The primary beneficiaries of that balance should be the fishermen and the fishing communities, so they should be the primary supporters of fisheries management. The attempts of governments to address the problems of 20th Century offshore fisheries, however, proceeded through top-down, command-and-control approaches, creating conflict where there should have been support -- conflict which then progressed into management of coastal fisheries, where it was never necessary. Backing out of the resulting mess won't be easy but I think it is necessary before we will see truly successful fisheries management.

    In short, I suggest that we need to re-arrange the way that people see fish/human interactions and the accompanying human/human interactions. If that can be achieved, your question (and much else in the fisheries debates of the past 70 years) would come to seem irrelevant. 

  • Rajasekhar Tota added an answer in Solubility:
    How can I get the solubility of an unknown polymer in a given solvent?

    Assuming the polymer is new without any data about it.

    Rajasekhar Tota · Indian Institute of Chemical Technology

    You could apply trail and check method in different polarity solvents.

    Different solvents like as nonpolar, polar and more polar. If you know the functional groups on your polymer you can directly select the solvent by the following way.

    If your polymer is without functional groups mostly soluble in nonpolar (xylene, toulene, hexane etc.,) and polar solvents (chloroform, DCM, ethyl acetate etc.,)

    If your polymer has functional groups mostly soluble in polar and more polar solvents (DMSO, DMF, water etc.,)

    More polar groups like as carboxylic acid soluble in more polar solvents only. for example polyacrylic acid and PVP.

    It means that by the functional groups information we can directly guess the favourable solvent for solubility. 

  • Carmen Camilleri asked a question in Teaching Methodology:
    How can Bulletin Boards be used as a teaching methodology to 18 year old students?

    Teaching Methodology: Can this method of Bulletin Boards be used with 18 year old students and if so which is the method to be used?

  • Akbar Reza added an answer in Ocean Acidification:
    Ocean acidification vs Ocean buffering effect. How can this be?

    I read some interesting articles about ocean acidification and chemical reaction in the Ocean. Ocean acidification occurs when pH-levels of the ocean decrease due to rapid increase of CO2 production in the atmosphere by human activity. However, how can the ocean be acidic whereas it has an extremely effective buffering effect (carbon dioxide-carbonate-bicarbonate equilibrium). And also, what are the roles of cyanobacteria and algae to convert CO2 for photosynthesis? I hope I can get some actual explanation to help make me understand the process. Thank you.

    Akbar Reza · Gadjah Mada University

    Thank you for all of your explanation :)
    Now i understand how CO2 concentration and rate of change can shift the equilibrium, nutrient-dependent carbon uptake by photosynthesis, basic concept of "neutral" pH, aragonite and calcite solubility, and terminology of acidification it self.
    Terima kasih! :) 

  • Saif Ullah added an answer in SWAT model:
    Does anyone know about the SWAT model error "index was outside of bound of array"?

    I am simulating a SWAT model. I provide all the input data, then I write all input file, it give error "the index was outside of bound of array". If anyone knows the solution of this problem, please guide me., Thanks for your positive response.

    Saif Ullah · Hohai University

    Dear Alireza Pirzad ,Abeyou Wale Worqlul, João Paulo Bestete de Oliveira,

       I believe that you all are fine and healthy,I have no words to say thanks because i am trying many times,your points help me lot to go  solution of problem.Thanks for your precious time.

  • E.Yu. Klimenko added an answer in Superconductors:
    Are we capable to predict Jc from resistivity measurement in a SC?

    Jcan be calculated from the magnetization data. Can we estimate it by making some assumptions on resistivity data; from an ρ-T graph?

    E.Yu. Klimenko · State Scince Center TRINITY, Moscow, Russia

    Dear Murat, If I understood properly you mean the critical current of high pinning SC (HPSC). The most simple answer: it is impossible because the critical current and M(H) are pinning dependent , and the critical temperature is not. (The R(T) shape depends on material inhomogeneity. The R(j) shape is also depends on material inhomogeneity, but the scale of j is pinning dependent.) The more precise answer: HPSC electrodynamics uses unlinear function   ro(T/Tc,B/Bc2,j/jc)  as an addition to Maxwell equations.  All the critical values are conventional ones and correspond to 0.5 of normal resistance.  This jc value can be reached almost never.  The commonly used "critical current" also is conventional value and it's phyical sence is questionable. For example,  jc is not equal to Ic/S sometimes. You may find some papers on HPSC electrodynamics in my list.

  • Saswat Mohapatra added an answer in Tubulin:
    What will be the best method to find out the tubulin binding site for any molecule?

    Can any body suggest methods to analyse the biniding site for any molecule.i have already some molecules having interaction with microtubule but now I need to know the exact binding site on the tubulin. 

    Saswat Mohapatra · Indian Institute of Chemical Biology

    Thanks Goutam for such a valuable suggestion.But I have the organic molecules not the  protein which bind to the tubulin.

  • Any suggestions to overcome membrane protein purification problem (expression) ?

    We are trying to purify a membrane protein expressed in BL21. We tried both N and C terminal his tag, but the protein doesn't bind well to the Ni column. Along with the protein of interest, many bands are appearing in elution. Strangely, the protein doesn't have (or very poor) UV absorbance. Also, I don't see any colour change when I add SDS sample buffer to this protein, but still see a band in SDS-PAGE. I tried Co instead of Ni, and got a band smaller than expected, but it didn't show activity.  I think something is happening during the purification because see enough protein in the membrane suspension. I use DDM to solubilise it from membrane because we want to crystallise the protein. Protein pI is 9.2, buffer pH is 8 in all cases, I mean from cell lysis to purification. I am new in membrane protein field. Any advice would be appreciated. Thank you 

  • Trushnamayee Nanda asked a question in Network:
    Can anyone help regarding NARX network in network timeseries analysis tool?

    How to set only feedback delay not the input delays in the network ?

  • Any possibility of using Carbon Nano Tubes in Self Compacting Concretes ?

    I am very keen to know about  carbon-nanotubes for increasing material properties.

  • Mohammad N. Elnesr added an answer in Landsat:
    What error does landsat data has ?? and how solve them ??

    I'm doing a research on a lake and I wanna use landsat data, what are the errors and how can I correct them ??

    how should I georeference the sheets and how can I correct the strip error ??

    Mohammad N. Elnesr · King Saud University

    Dear Milad,
    To correct the strip error of LandSat, there is a simple tool where you can download in this linked page below.

  • Ashok Ahuja added an answer in Plant Tissue Culture:
    Is there any difference between mg/l (ppm) and n/L (Molarity) ?

    What do you think of the concentrations used in tissue culture papers? For example effects of 0.5 mg/L IAA or IBA on root formation.... Is this a comparable issue?

    Because this also means 2.9 uM IAA or 2.5 uM (micro-molar) IBA, molecular number is now completely different, in spite of similar weight of compound (0.5 mg/L).

    Ashok Ahuja · Indian Institute of Integrative Medicine

    Yes both are different things. Better would b use molarity most appropriate and convenience.

  • Shivani Poornima added an answer in Pamphlets:
    How successful have information pamphlets to guide patients' and ensure compliance pre and post operative been for other nurses?

    Many information leaflets / pamphlets are given to patients' but despite explaining there is some degree of non compliance to pre operative preparations and post operative discharge care for my Gynaecological patients' for surgery.  Language in English is not a barrier for many patients'.

  • David Hoaglin added an answer in MANOVA:
    Is it ever correct to use ANOVA for multiple dependent variables?

    As far as I understand, if one wishes to analyse multiple DVs, MANOVA should be used. Risk of Type I errors will be increased by performing multiple ANOVAs or multiple t-tests without corrections. However, I have seen several publications where a single ANOVA is used and multiple DVs are entered as a factor. Is this ever advisable, and if so what is the rationale?

    Thank you

    David Hoaglin · University of Massachusetts Medical School

    Amber,

    I would like to see examples of analyses in which "a single ANOVA is used and multiple DVs are entered as a factor"; but I interpret that description as saying that the data on the various DVs are arranged as a single DV for the ANOVA, and the identity of the particular DV is given by a factor (i.e., a set of indicator variables).

    If one writes out the model corresponding to such an ANOVA, it involves a very strong assumption: the other factors have the same contributions to each of the DVs, and the means of the DVs differ only by a constant.

    If the ANOVA model actually contains interactions for the DVs with all the other factors, the result will be similar to using a separate ANOVA for each DV, but assuming that all the DVs have the same "error variance" (for which the error mean square in the combined ANOVA will give a pooled estimate).  This might make some sense if the various DVs are closely related (e.g., have essentially the same scale) and could reasonably have the same error variance.  Otherwise, it would seem difficult to justify.

    Combining the DVs in a single ANOVA hides the problem of multiplicity but does resolve it.

  • Rabii Chaarani asked a question in QGIS:
    Geologic Symbols(.SVG) for QGIS?

    Please i need help, where can I find Geologic Symbols(.SVG) for QGIS?

  • Has there been research to showing that increasing education improves ethics in a community?

    'Students often know the right thing to do. How can schools help them to do it?

    The numbers are in and they don't look good." That was the assessment of the Josephson Institute of Ethics last October, when they conducted a survey about the moral standards of more than 20,000 middle and high school students. Almost half the young people reported stealing something from a store in the previous 12 months. In the same period, seven out of 10 cheated on an exam.
    Should we be worried? Many observers say that we should. We see evidence of more antisocial behavior than ever among our youth—a sort of divorce between personal ethics and everyday behavior.'

    Has there been research to show that with increasing education, there has been improved ethics in a community?  Can you share, give some evidence? Thanks.

    Maria Bettencourt Pires · New University of Lisbon

    My own personal views tell me that it may be difficult to record a link between education and ethics, although there is obvious relation, because education takes at least one generation to produce effects and ethics or the need for ethical behaviour are the instinctive and intrinsic result of an educated social interaction.

  • Peter T Breuer added an answer in C#:
    How can I sort a huge file without using a large memory?

    I need a C# code or algorithm for sorting a file that contain students records. I don't want use all memory for sorting this file and want to sort each record. Do you know similar code or algorithm?

    Peter T Breuer · Birmingham City University

    He says "or algorithm" (and his topics list "C++", which means "C" too!). People are telling him what algorithm to use, or what standard C/C++ library functions to use. 

    Those who are listing command line solutions using posix commands are not wrong either (windows does posix, does it not? And there are the cygwin tools that run on it). It's just counterproductive, since he wants to minimise memory use and using stock commands is not the way to go about that.

    The answer is always going to be the same ... use mergesort directly, and/or presort fragments and mergesort the results. Whatever C# solution exists is going to have to do that too! But it's not rocket science to write a mergesort. It must be about 50 lines, whatever language you write it in, so nothing here is worth straining oneself over.

  • How do you go about choosing unused metal for doping the ZnO nanoparticles for Photoluminiscence studies?

    ZnO nanoparticles using solgel method,TEA as surfactant.

    A. Sivagamasundari · Pondicherry Engineering College

    By varying concentration with the unused metal for low temperature synthesis in sol-gel method as citric acid as a chelating agent. In PL studies give the defect emission peak.  

  • Antony T Vincent added an answer in Exons:
    What is the best method for screening mutations?

    We sequence patients DNA in order to detect the different mutations associated with the disorders; if it is simple gene with few exons and small number of patients then it is feasible to use either capillary  or next generation sequencing, but if we have a complicated gene , many exons, and many patients , it is more feasible to do mutation screening before sequencing. Because there are many mutation screening  methods, the question now, what is the best method for doing mutation screening which is accurate, fast and cheap?

    Antony T Vincent · Laval University

    If I well understand, there is ONE "complicated" gene with mutations causing disorder. It is correct? What is the length of the complete gene (exons + introns)? In fact, some time, it is a single mutation in an intron which cause the disorder : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2855871/

  • Sundarapandian Vaidyanathan added an answer in Tea:
    What are the medicinal benefits of lemon tea?

    Some excerpts from the article: "Medicinal benefits of lemon tea" by Mala Srivastava:

    "Tea is a good calorie-free substitute for sugary beverages, according to the Harvard School of Public Health. If you add a squirt of lemon juice to your tea, it will not only enhance its flavor but will also provide multiple health benefits. For example, if you are experiencing nasal congestion, drinking lemon tea can help to decongest your blocked nose, reports the University Health Service of Rochester University.

    Vitamin C Benefits

    One fluid ounce of lemon juice contains 12 milligrams of vitamin C. Water-soluble, vitamin C helps fight free radicals -- rogue molecules that damage your DNA. Free radicals may contribute to the development of diseases such as cancer and heart disease, notes University of Maryland Medical Center. By counteracting the negative effects of free radicals, vitamin C helps decrease the risk of developing cataracts by 80 percent, according to the book "The Secret Benefits of Lemon and Honey: Secret Guides.” In addition to healing wounds, vitamin C helps maintain and repair your teeth and bones. Moreover, your body requires this antioxidant to form collagen, a protein used to build skin, blood vessels, cartilage and tendons.
    Bioflavonoid Quercetin

    Citrus fruits, such as lemon, are one of the primary dietary sources of quercetin. A flavonoid, quercetin protects the insulin-producing cells in the pancreas from the damaging effects of free radicals. In addition, quercetin has an anti-inflammatory effect, as it helps stabilize the cells that release histamine in your body. Histamines are chemicals that trigger allergic reactions. According to the American Cancer Society, quercetin can inhibit the growth of cancer cells and can help promote apoptosis, a type of cell death. Animal studies have shown that quercetin may exhibit a protective effect against certain types of cancer, especially colon cancer.


    Blood Sugar Control

    High blood sugar occurs when your body produces inadequate amounts of insulin or when it cannot utilize insulin properly. Hesperidin, a compound in lemons, can modify the function of enzymes that affect your blood sugar levels, according to a study published in the January 2010 issue of the “Journal of Clinical Biochemistry and Nutrition.” This not only shields your body from the early stages of diabetes but also helps avert diabetes complications if you already have high blood sugar. Additionally, hesperidin has cholesterol-lowering effects.
    Powerful Limonoids

    A study published in the “Journal of Nutrition” in April 2005 revealed that lemons contain compounds called limonoids that have the potential to impede the growth and development of cancer cells. Not only did limonoids decelerate the growth rate of cancer cells, but they also enhanced cancer cell death when tested against human cancer cells. The study further states that these anti-cancer agents have free-radical scavenging activities."

    Your views are welcome! Thank you - Sundar

    Sundarapandian Vaidyanathan · Vel Tech - Technical University

    Dear Abedallah:

    About 'Samahan', it is a health drink - see Amazon link for details!

    I think this herbal drink is made by Sri Lanka and it is available for internet order.

    Ingredients
    Adhatoda vasica Nees. (Acanthaceae),Alpinia galanga Willd. (Zingiberaceae),Carum copticum Benth & Hook. (Apiaceae),Coriandrum sativum Linn. (Apiaceae),Coscinium fenestratum (Gaertn.) Colebr. (Menispermaceae),Cuminum cyminum Linn. (Apiaceae),Evolvulus alsinoides Linn. (Convolvulaceae),Glycyrrhiza glabra Linn. (Fabaceae),Hedyotis herbaceae (Linn.) Lam. (Rubiaceae),Piper longum Linn. (Piperaceae),Piper nigrum Linn. (Piperaceae),Premna herbacea Roxb. (Verbenaceae),Solanum xanthocarpum Schrade. & Wendl. (Solanaceae),Zingiber officinale Roscoe. (Zingiberaceae)

    Thanks - Sundar

  • Why a discrete time signal when converted to frequency domain using DTFT or DFT is continuous? Any mathematical proof behind it?

    Let x(n) is a discrete time signal. We have done the Discrete Fourier Transform of it. Then the spectrum we get in frequency domain is continuous. How it happens?

    Karl-Heinz Witte · Hochschule RheinMain

    Only a periodic Signal gives a discrete spectrum. This must not be the case when the signal is discrete. If a DFT shall give a correct spectrum it is assumed, that the signal is discrete AND periodic. Only if both conditions are fulfilled then it gives also a correct  diskrete spectrum

  • Quick live dead stain for P.falciparum - can anyone help?
    Is there any live dead stain that works on P.falciparum within 2 hours from staining to observing?
    Maciej Kochanowski · Państwowy Instytut Weterynaryjny

    I suggest you to use LIVE/DEAD Bacterial Viability Kit.

  • Does Q.M. need refinement?

    A system of ideal gas can always be made to obey classical statistical mechanics by varying the temperature and the density. Now a wave packet for each particle is known to expand with time. Therefore after sufficient time has elapsed the gas would become an assembly of interacting wavelets and hence its properties would change since now it would require a quantum mechanical rather than classical description. The fact that a transition in properties is taking place without outside interference may point to some flaw in quantum mechanics. Any comments on how to explain this.

    L. I. Plimak · Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy

    IMHO, the ONLY reason for amending QM may be an EXPERIMENT which is IMPOSSIBLE to explain in QM terms (cf. blackbody radiation vs classical mechanics). All known logical, interpretational, etc., difficulties of QM are OUR problems and not those of QM.

  • Kongkeat Jampasri asked a question in Soil Analysis:
    What will I choose the ratio of extractant:soil between 5:1 and 2:1?

    How can I extract soil samples by extraction by DTPA-TEA solution at pH 7.3 (5:1 extractant/soil ratio or 2:1) for analysis of heavy metal availability in lead and TPH co-contaminated saline soil?

  • Energy conservation feedback?

    Hello,

    Hope you are well.
    I am writing a journal paper on spreading energy conservation awareness using the power of social networking.

    I would really appreciate if you could spare a minute to fill a survey for my research. This is crucial for completion of my paper and hence I have included only few important questions which shouldn’t take more than a minute to complete.

    Please follow the link to the survey:
    SURVEY URL: https://www.surveymonkey.com/s/8LYRG5M

    I would be great if you can forward it to your office colleagues and friends too as this would be of immense help to me and all individual responses will be kept confidential.

    Hope to receive a positive response from you. Thanks in advance!!
    Wish you a Merry Christmas and a Happy New Year!
    Regards,
    Amruta Nayak
    MS in Industrial Engineering
    University at Buffalo, the State University of New York

    Gayan Sirimanna · University of Moratuwa

    Done. Hope this is helpful.

  • Chong Leong Gan added an answer in Stress Testing:
    Is Au coated Ag wire better than Pd-coated Cu wire in terms of biased HAST reliability?

    Au-coated Ag wire humidity reliability

    Chong Leong Gan · Universiti Malaysia Perlis

    Thanks! Any literature on Au-coated Ag wire published so far?

  • Mehmet Duran added an answer in Transformer Design:
    Can anyone give guideline in order to design a phase to phase voltage transformer in order to use discharge equipment for a capacitor bank?

    I want to design a phase to phase single phase voltage transformer which is used for placing capacitor banks on the system. For this purpose, I need a voltage transformer with an air gap coil (in order to have constant L value). So, I need some advice about materials or document which i can use. thanks a lot.

    Mehmet Duran · Middle East Technical University

    thank you Mr. Desai but there are some limitations such Tdischarge < 10 sec and Vcapacitor < 70 V. So, transformer inductor value is important for me. While capacitor is discharging, this transformer inductor value changes according to flux. Can i assume the transformer inductor value as constant ( i.e. L=500 H). Is it sufficient assumption?

  • Lorenza Ferro added an answer in Microalgae:
    ITS-2 region PCR amplification in microalgae: why do I have two bands?

    Hello, I am trying to characterize some microalgae strains and I am doing PCR using primers for the ITS-2 region. In some strains I obtained 2 PCR products: one is in the expected range of size (600-1000 bp), the other one is higher and I really don't know what it is.

    Anyone has experience with the amplification of this region?

    Lorenza Ferro · Umeå University

    Thank you all. I sequenced my bands and obtained good results.