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
  • Maurice Kwékam added an answer in Petrology:
    What is crustal delamination and how does it influence the petrogenesis of alkaline rocks, e.g. lamprophyres?

    Analytical data of lamprophyres (minette and spessartite) display a primitive character and are enriched in LILE with depleted HFSE. The geotectonic environment as suggested by trace element data suggests both subduction and rift settings.

    Maurice Kwékam · Université de Dschang

    Delamination model: Model where the dense root of an orogen detaches and sinks into the underlying mantle. To have more (H. Fossen, 2010. Structural geology page 350)

  • Rich Philp added an answer in Mathematics Education:
    What is the link between numeracy automaticity and student performance in the regular classroom?

    Many students in urban classrooms have mathematics difficulties. In particular many have very poor basic numeracy skills. I am currently writing my dissertation in this area. The approach will be to do a supplementary intervention to improve automaticity and to study how students performance in the classroom is impacted by improved levels of fluency. This will hopefully free up working memory thus allowing students to engage in the actual mathematics and not be bogged down with the underlying numeracy calculations and facts.

    Rich Philp · Dundee College

      Automaticity is engendered by practice and repetition .

      A common complaint of less able students is that , because they take more time to come to  an answer for a mental task , their peers or the tutor answer the problem aloud without being invited to , this has a significant impact on their willingness to engage further .

      This situation cannot be solved without adequate time being given for a response :  question-by-question silent mental arithmetic tests and time given over to exploring a variety of mental algorithms with graded problems enables students .  This is not usually time-tabled and is the luxury of the able - less able classes get whipped over the course without the extra input needed .

      Automaticity allows for greater speed of delivery , calculation and collaboration - thus ''performance' overall .  Certainly you have identified 'working memory' as the key and recall is the basis of it , but understanding of or having a visualisation of what a written number/computation means is the essential precursor .  It's about literacy first , computational skills come after .  Written Maths uses ideograms , these are meaningless without recognition .

  • What are the best O-rings in terms of chemical resistance?

    I have an electrochemical cell which houses solutions via PEEK material and seals with a couple O-rings. For many solutions the Viton O-rings I've been using work just fine, but for some solutions (particularly those containing Grignard reagants) the O-rings are not compatible and will swell and even degrade relatively quickly. Can anyone suggest the best O-ring material for use with chemicals such as these?

    Paul M. Zelisko · Brock University

    Fluorosilicones seals will likely provide you with the flexibility and chemical resistance that you are looking for.

  • How can one effectively blend instruction and assessment in a lesson? Should you have an equal number of strategies for instruction and assessment?

    I noticed that many teachers prioritize instruction over assessment.  They tend to employ more strategies for instruction.  The assessment formats or techniques they use are usually discrete point.  Would this affect the overall quality of teaching?

    Lucet Montgomery · United Nations Educational, Scientific and Cultural Organization

    There are a few factors that you may want to examine such as the curriculum being used by the instructor, the method of delivery, how many topics have been covered on the syllabus up to the point that the assessment is being devised for delivery to the learners. For example some assessment strategies are inadequate tools for the answer which is required. Phrases such as list, define and state are less informative than explain, describe, write an essay on the following. There are a range of flexible options that may be used for assessment that can be made equal to the instruction which is employed by instructors. You may want to research assessment tools and measurement instruments alongside delivery modalities in the classroom. Analyze both to derive a suitable conclusion based on evidence from your research.

  • Should the letter ‘e’ in e-learning mean ‘no face to face interaction’?
    There has been a tremendous advancement in computation and communication technology. The concept of e-learning has come into existence. The proponents of this form of education suggest complete automation that is totally to avoid human interaction in the classroom. What is in your opinion, what should be the correct pedagogy which would be compatible to present technological advancement?
    Sérgio Eustáquio Silva · City Hall of Belo Horizonte, Brazil

    Hello Phillip,
    Partly agree with you. You are very right when he says that experiments involving technology often do not fulfill their promises. But I believe we have made ​​substantial progress towards a strong pedagogy also for e-learning (but I am still aware of the current challenges). However, as you say although we can not use technology also does not mean that we should do this. In many cases has made itself indispensable. An example: work in a municipal school system (Belo Horizonte), which has 200 schools (which will reach 400 because in each of them being a unit linked child education) linked to the municipality, arranged in a geographical area of ​​331.40 sq km . Are 15 000 teachers (from kindergarten (0-5 years) to 9th grade of elementary school). There is no way to update and train this number of teachers without thinking of some process of e-learning. Exists, but there turns out to be infeasible when compared to the advantages of e-learning. Of course, as with everything in life there are gains and losses.
    For our case the benefits are greatest. Then, we necessarily find that a strong and modular pedagogy for this. The point I'm getting at is that not always it will be decided only by our pedagogical beliefs but there are also practical issues of cost, speed, mobility, etc ... acting in our decision-making processes. And I'm talking about a state capital. As a country we have very distant places, even remote which also brings challenges that e-learning can offer several advantages.
    But I totally agree with you about the need to have a strong pedagogy for e-learning. For my part I think their use, combined with face to face meetings from time to time can be a good solution. I am an enthusiast of human relationships face to face so you can imagine my dilemma l0l. But I think we have to match that and a strong pedagogy of e-learning (which still needs to be greatly improved, researched and understood).
    Greetings to all,
    S.

  • Yuanchao Geng added an answer in Pulse:
    How can I change the size of a laser focal spot within a short time of 10ns?

    If a laser pulse has only 10ns width, how can I change the focal spot size of the pulse in real time. For example, the diameter of the spot is 500um in the first 5ns, and I want it to be 250um in the next 5ns. Could anyone tell me how to handle this.

    Can any device modulate the wavefront of a laser pulse in several nanoseconds.

    Yuanchao Geng · China Academy of Engineering Physics

    Dear John,

    It's so kind of you to share your rich experience and knowledge with me. Thank you for your advice on choosing crystal and analysis on how to use the polarization modulation of pulse . I'll consider what you said.

  • Muhammad Youssef asked a question in Schiff Bases:
    Ruthenium complexes and reflux temperature

    Please I am asking about the range of temperature during reflux of Ru(DMSO)4Cl2 with schiff base ligands ,because the elemental analysis after reflux at temperature near 150 show that the complex may be decomposed or may be schiff base ,so may be it need only stirring without heating ?

  • Simrat Kaur added an answer in Cyanobacteria:
    How can anyone have conformation of cyanobacteria Spp.?

    Hi! i am looking for cyanobacteria Spp. conformation protocol or tests?

    Simrat Kaur · National University of Ireland, Galway

    Grow them under nitrogen free medium. As the cyanobacteria contain phycocyanin so the absorption spectrum give maximum absorption at around 750 nm.

  • Garret Vincent added an answer in Citric Acid:
    For antigen retrieval, is there a difference between using Citric Acid (Anhydrous) or Citric Acid Monohydrate?

    Is it better to use one over the other, or do they produce similar results?

    Garret Vincent · University of Pittsburgh

    Thank you for your help!

  • Denboy Kudejira asked a question in Political Ecology:
    Looking for a PhD Opportunity on Political Ecology of Climate Change Adaptation - Any leads?

    I am looking for an opportunity to undertake PhD research on the political ecology of climate change in shared resource/transboundary settings. Specifically, my interest is to explore how countries are dealing with climate change in shared resource systems (river basins) in Southern Africa while at the same time responding to national socio-economic development needs. I can provide more information about my academic and professional background on request.

  • How can I measure the drilling force on a hydraulic cylinder?

    We design an electro-hydraulic machine tool, and we would like to make an experiment in our laboratory.

    Enclosed you can find the hydraulic cylinder.

    Thanks for the answer.

    Amir Kessentini · King Khalid University

    About U're last question, I think that you can easily use matlab. You can see my paper "EFFECT OF TOOL GEOMETRICAL PARAMETERS ON VIBRATORY BEHAVIOUR IN DRILLING" for equations development.

  • Helena Papacostas asked a question in Müller glia:
    How can I predict possible miRNA targets in silico?

    I have a list of 6 miRNAs that we think could be important during the process of dedifferentiation of Müller glia to retinal progenitors in mouse, we want to search for possible targets but the programs and pages we have used have yield no results.

  • Simon Schröder added an answer in Data Structures:
    What is the best proven data structure to store and access the information about large number of nodes, edges and clusters?

    I am working on the layouting algorithm, for this i need a data structure which should able to store, access information about nodes, edges and clusters very efficiently
    This structure should able to handle atleast data about 10000 entities. Please help me if nay one has worked on such problem?

    Simon Schröder · Fraunhofer Institute for Industrial Mathematics ITWM

    Usually, you'll need to make a trade-off between inserting items into your data structure and just accessing items. Based on how often you are going to change your graph and how often you just read from it different data structures are more efficient. There is no one-size-fits-all solution to your problem. Without deep knowledge of your problem it is impossible to give the right answer.

    10000 elements is not a large number of items for today's computers. Almost every algorithm might be fast enough for you. Only if you need very high performance does it make sense to use the kind of hacks that Jochen has suggested. Otherwise a regular data structure will be sufficient (and a lot easier to maintain). Sometimes it is not worth it to spend a lot of time tweaking a data structure that nobody is able to maintain. So, ask yourself the following: Will the project stay for many years (10 years+)? Will this be a data structure that is only written once and never touched again? If the answer is "yes" to both questions you can consider looking for the optimal solution, but you don't have to. Don't spend to much time for complicated code that nobody else will ever want to touch, but they might have to. Be kind to your future self ;-)

  • Yasser M. Abd-elrhman asked a question in Body Fluids:
    What is the meaning of Simulated Body Fluid?

    Can I consider the Ringer's solution as SBF.

    I read that Hank's solution can be used as SBF. Are there any other ready (can be purchase it from companies or labs ) solutions can be used as SBF? 

    Thanks in advance

  • Yun Shi added an answer in Gromacs:
    How can you prepare your model of protein before going through Gromacs and Autodock programs?

    Reference(s) would be great.

    Thanks!

    Yun Shi · Simon Fraser University

    For missing residues, there are many free tools available online. Depending on how many missing residues you have, it could as easy as adding a alpha carbon manually or as complicated as building a homology model/threading.

    The protonation state of certain amino acid residues may also cause deviations in your docking/MD, and I would use online tools like MolProbity to deal with this issue and look into those problematic His visually.

  • Sarah Warren added an answer in Phylogenetic Tree:
    Can anyone recommend software for creating Single Sequence Phylogenetic Tree?

    Hello,

    I am trying to create a phylogenetic tree using my single protein sequence. I know that phylogeny.fr pulls from other databases to create a tree but does anyone know of other software? I feel as though it is an incomplete tree.

    Thanks

    Sarah Warren · Alberta Health Services

    Thanks everyone. I've started researching the various methods within Mega 6.0 so I think that is what I will use.

  • Cheng Zhou added an answer in Landsat:
    I want to perform classification on LANDSAT imagery, using automatic classifcation tool

    Hello All , i am trying to build a tool which can be used for automatic classification of LANDSAT Imagery into different classes , could some one please suggest on how to go about that

    Cheng Zhou · University of Antwerp

    Weka may help you

  • Anna Maciag added an answer in Ligation:
    How can you increase the transformation efficiency?

    I have been trying to do the transformation for the past couple months, but I have no luck on getting the high efficiency.

    I have tried to make the inserts, digested them with sacI and speI restriction enzymes at the same time, did gel purification to purify the insert dna, and run on the gel again to compare if I got the insert digested properly.

    I did the same procedures with the vectors, except digesting them sequentially with sacI first, and then speI.

    I tried to treat vector with or without phosphatase,and treat kinase with or without kinase, and ligate the vector and insert with 1:5 and 1:10 ratio with two different ligate from either promega or thermo science.

    The ligation condition was either at RT for 2 hours, or at 4 degree C for overnight. And then, I transformed 100 ng of the ligated product into 100 uL of comp. cell with 9x10^8 transformation efficiency.

    However, the average transformation efficiency for the ligated product was only around 10^4. The one for ligated product with treatment of phosphatase and kinase was even worse than the one without treatment.

    I still got around 10% of wildtype for my colony pcr and 10% unsuccessful ligated products.

    Please help me... any commons and suggestions will be appreciated.

    Anna Maciag · IRCCS Multimedica

    The efficiency of ligation depends in many cases on the vector you use and the length of the fragment. For inserts < 3000 bp I usually amplify them by PCR using Pfu Polymerase with primers tailing the restriction site and 2-3 additional bp  due to digest the PCR products directly. So what I usually do is:

    - I amplify the gene of interest  (2 PCR reaction of 50 ul)

    -purification of PCR products

    - digestion of the insert  and vector with restriction enzymes

    -purification of the products (vector from the gel and the insert directly from enzymatic reaction)

    -quantification and reaction of ligase

    For ligase reaction I usually use no more than 50 ng of the vector and the maximum volume of insert I can put (very often the ratio is more than 1:10) and usually it works quite good;)

    I hope it was helpful

  • Fairouz Bettayeb added an answer in Publishing:
    Should professors jointly publish papers with students?

    At what point should/could a student be encouraged to publish a worthwhile, viable paper on his own vs. the professor adding his name?  Consider the academic level of the professor/student collaboration:  undergraduate, master's, doctoral.  What is the amount and value of the professor's contribution--a minor edit, a substantial rewrite, repeating an experiment, etc.--that determines when the professor and student should publish jointly?  Whose name goes first?  Is joint publishing a misuse of a student's work?  Should professors give students with potentially publishable papers all the help they need without requiring their names be used? 

    Fairouz Bettayeb · Centre de Recherche Scientifique et Technique en Soudage et Contrôle

    I also agree with @Hanno, that advisers and professors have not to be part of the students' papers who must defend by themselves their works and diplomas. Professors are able to write their science and the team work results with their language and their philosophy as an added value to the science. It is as well their job to be good advisers for their students. No need  for co authorship for that

  • Cheng Zhou added an answer in Classification:
    Which method(s) do you recommend for classification based on Likert scale?
    A few experts scored some risk factors based on the likert scale. Now, I want to classify them in a few classes.
    Cheng Zhou · University of Antwerp

    SVM maybe

  • How do I test whether slopes of these two lines are significantly different?

    Hi all, I came across with this problem: how to test whether slopes of these two lines are significantly different? A detailed explanation of scenario is attached. In my opinion,"to test the slopes" means to test the difference between 100 - (var1p / var1b)*100 and 100 - (var2p / var2b)*100 , which is how much variable decreased after treatment. Since var1b, var1p, var2b, var2p come from the same set of subjects, there is some correlation there. So how do I test the slopes? What is the distribution? 

    Thank you all for help!

    Xin Yang · University of Alabama

    I really appreciate it, Jochen. Thank you very much. I am trying to contact a local statistican now.

    "Subject 1" has two measurements for "Day 1", yes. But they are different. Say, pretreatment day 1 may be 01-01-2014, after treatment is 05-01-2014. But the subjects are the same. 

    The second variable is the time (minutes) the person wake up after sleep. It is the same day and same subject. Is it sensical to compare the reduction these two time  (minutes needed to fall asleep and minutes awake during the night) after treatment?

  • Prediction paradox . multicollinearity?

    When I used multiple linear regression between profit vs cash deposit then lift was 43% . When I used profit vs age then lift was 20%. But when I used profit vs (cash deposit + age) then it was only 41%. Why is it lesser than 43? How is it possible?

  • Benjamin Matthias Barth added an answer in Ants:
    How can the neural network of ants help in the establishment of their eusociality?
    Ants are known for being eusocial. In this set up, the parents live with the young, everyone pitches into taking care of the children and there is a reproductive division of labor. In the cellular level, how are ants able to become eusocial?
    Benjamin Matthias Barth · Martin Luther University of Halle-Wittenberg

    For the evolution of eusociality it's rather kin selection playing the major role in that Hamilton's rule br - c > 0 has to be fulfilled, where b = benefit, r = relatedness, c = costs. I.e. if relatedness and other factors lead to that, altruistic helping may evolve.
    In the beginning parental manipulation (i.g. less feeding of some offspring) may lower the fecundity an promote helping in offspring. During eusociality maintenance also queen signals may prevent ovaries to develop in workers, so that they are doomed to be helpers. I recomment the book by Bourke and Franks (1995): Social evolution in Ants

  • Pierre Evesque added an answer in Academic Writing:
    How far are scientists willing to go to publish their rejected articles or scientific reviews?
    I am wondering how many papers are sleeping in a computer file because they were rejected or not completed.
    One would say very few, since a paper "has to be published".
    Asking 9 university-based physicians, 5/9 reported to have 1 to 3 papers into their personal files...that will never be re-submitted!

    Would be glad to hear from a "larger size", do you have unpublished papers?
    Pierre Evesque · Ecole Centrale Paris

    Dear all,

    I believe that nobody is really interested in research, since no body open the fight against the power of edition.

    This power is only efficient when papers are proved to be correct.

    There is no proof at the moment, So scientific edition is liing

    And it never claims it.

    By the past we new that, and people tried to preserve the eficiency.

    Now we are just wanting to publish and to emphasize it.

    I ask the AERES to help getting correct evaluation. It does not care, it is not paid for such a problem.

    I asked it (AERES)  for helping respecting thesis results. It told it, ant it told me it is a personnal problem.

    (AERES is the French arhetype of nothing, which warrants the scientific research. It is somekind of administration with a heads which is never responsible, or for so little so that one cannot find its real efficiency)

    Where are the scientists, where is their consciousness?

    We need to group together to build a new community, without most pseudo scientists " who wants to lie" and make as is... not to make science , facing to realness.

    Alessandro, where can adress you my files you put it on the web.

    Do you find normal that medical CNRS comity paid by CNRS)  told I am ill, while no other physician confirmed their diagnostic, except the superior comity who never saw me and who never asked for a new diagnostic.

    France seems to look as USSR and as the "psychiatric paradise" open by Staline, .

  • Thuany Ribeiro Silva asked a question in Ulva Lactuca:
    Could anyone recommend me protocols or papers dissociation of plant cells?

    I am trying to accomplish dissociation of cells from the green alga Ulva lactuca (Linnaeus), or hold a plant cell culture.

  • Halfdan Carstens added an answer in Hydrocarbon:
    I am curious to know about hydrocarbon reservoirs producing from spiculites. Where, and what are the reservoir characteristics?

    Spiculites reservoirs have recently been found in the Barents Sea. I would like to know more about them.

    Meaning that the reservoir is built during migration. Which would then require a second migration phase to fill up the reservoir?

  • Suzana Guedes added an answer in Psychotherapy:
    Is there an established neurobiological basis or a reasonable theory regarding how eye movement desensitization and reprocessing (EMDR) works?
    I have tried to do some research but the explanations are not very satisfying to me. On the other hand, if it really works, take it if you can get it right?
    Suzana Guedes · Universidad de Huelva

    Some studies show the changes in the brain (with neuroimages) before and after EMDR aproach. So neurobiological changes happen, but we still don,t know exacly how or why.

  • Amir Kessentini added an answer in Vibration:
    Hello everybody, can anyone help me how to measure vibration on buildings in towns due to volume of vehicles on highway?

    Can anyone answer me the simplest way to do it.....

    Amir Kessentini · King Khalid University

    by using accelerometers fixed at the base of the building and at each floor.

  • How can I explain the results of PCA from feature extraction?

    I extract some features from a signal and I put it in my ANN and got Mean Error (ME) and Standard Deviation (SD).
    Then I applied PCA on the proposed feature extraction and I got worst result!
    Do you know any reason to explain what this happen?

    Loganathan Murukesan · Universiti Malaysia Perlis

    Dear Azadeh,

    Feature reduction using PCA does not mean you can get improved results. It just a method to retain most of the variances in the data while sacrificing some informations. It usually works well. Try retain 95-99% of variance then retrain and retest the ANN. If the result is not improved, then use feature selection rather than reduction. In feature selection, you can try Sequential Forward Selection or Correlation based Feature Selection. CFS is better than SFS.

    Good luck!

  • Aamir Iqbal added an answer in DNA Isolation:
    I am having DNA Extraction from Saliva, my question is that Why the pallet don't dissolves in the tube after adding DDH2O?

    I am extracting DNA from Saliva through Manual Protocol NOT with the Standardized Kits. Right at the end of the extraction when I get the DNA Pallet that need to be dissolved by adding De-ionized water which normally does dissolves and we process it to further step Gel Electrophoresis. But I am facing difficulty in this step that is the pallet which does not dissolves. I am using Phenol, Chloroform, EDTA, Tris, BME and PK and Lysis buffer. Some of my colleagues ask me to wash the Phenol with TAE Buffer solution this will help you in proper extraction. Kindly help me out in this regard.

    Aamir Iqbal · Hazara University

    Shu Canwei, Yes I do use Isopropanol