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.

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  • Matts Roos added an answer in Quantum Gravity:
    Is there a quantum gravity theory that can generate entire table of standard model particles with a single formula?

    A quantum gravity theory based on the equivalence of gravitational and relativistic mass is developed from Newton's inverse square law which assumes a form of Schrodinger like wave equation. Solution of this wave equation generates the entire table of standard model particles.Is there a comparable theory that can do the same thing?

    Matts Roos · University of Helsinki

    It's about time to forget about SUSY. But I realize that it is not so easy for those who spent 20 years doing SUSY research.

  • HIF1alpha Western-Nuclear Extraction Help

    For HIF1 alpha western blot, while doing the nuclear extraction, on following the volumes in the protocol (100ug tissue and 300uL solute) protein concentration in the samples prepared is too low. Can I increase the tissue weight to increase the sample concentration? Would that result in incomplete lysis? 

    Osvaldo Contreras · Pontifical Catholic University of Chile

    Your tissue concentration is very low. So, you should augment the amount of protein. Also, I recomment you to check your antibody, which antibody concentration are you using? and if your antibody is the appropiated. 

  • Isn't it true that children in poor countries must work to feed themselves and their families?

    That is an image that has been portrayed and may seem acceptable to some. But the reality is that children wouldn't have to work if employers paid their parents a living wage and if governments made affordable education for all children a priority. And most child weavers are working in debt bondage, which means that they do not even earn a wage. What do you think? 

    Amin Talebi Bezmin Abadi · University Medical Center Utrecht

    It is absolutely wrong and against human right, no need to ask my friend!

  • Pietro Pilo Boyl added an answer in Collagen:
    Problems culturing primary cells on glass for confocal

    I am trying to grow primary type 2 alveolar epithelial cells on glass for confocal. Normally for my experiments I would culture them on collagen coated plastic however when I collagen coat glass they refuse to sit down. After trying many different methods of collagen coating glass chamber slides (TC treated) and coverslips someone suggested that I use thermanox coverslips. The cells grew well on these however when I tried to image them there was just a fluorescent haze – I could not even pick out my cell nucleus.  

    The cells are definitely present as they are visible by brightfield and the confocal settings were correct as I imaged other cells on glass chamber slides at the same time.

    Is a general problem with thermanox coverslips and confocal? Does anyone have any suggestions of how I might proceed next?

    Thank you for your help!

    Liz

    Pietro Pilo Boyl · University of Bonn

    Hi Liz, indeed primary cells often don't like to grow on glass. We grow primary neurons on coverslips, but the treatment you have to do to the glass is quite harsh, with nitric acid and boiling and finally coating. For ES cells, which also don't like to grow on glass, we use the Nunc Lab-Tek Permanox Chamber Slides (Cat. 177429 for the two-well), which are made of a special plastic suitable for fluorescence and you can mount them with your regular coverslips.The thermanox coverslips are better suited for EM, since they are autofluorescent in the range 380 to 545nm (by company specification), which means they allow only infrared labelling (starting possibly with Alexa 594/Texas Red and then Alexa 647/CF633/etc... but I never tried personally!!)

  • How a yield point of the material (metal in particular) can vary with the crystal structure?

    What is the relation between yield point an crystal structure of metal.

    Karthik Dhandapani · VIT University

    Thank you Amit Sinha. 

  • Can anyone recommend a questionnaire to use to examine nursing care of pressure ulcer prevention?
    Nursing care is seen as essential for preventing pressure ulcers. However, what constitutes nursing care in pressure ulcer prevention need to be examined and its effectiveness assessed. Current evidence indicates that pressure ulcers have remained a clinical problem and compromises safety of patients in all healthcare settings.
    Panayiotis Papanikolaou · University of Glasgow

    There are different ways of looking into this issue. I am quite happy to help with this issue, as I have extensively published in the area of pressure ulcers, nursing decision-making, particularly, in the community.  Further, one of latest paper in nurse decision-making and pressure ulcer prevention published by the Journal of Research in Nursing has been selected by the editors for open discussion thru the twitter social media. You are most welcome to get in touch with me.

  • Antonio Bova added an answer in Human Trafficking:
    What are the biggest challenges to doing research on human trafficking?

    What are the biggest challenges, obstacles, barriers that researchers have faced when attempting to study human trafficking.  The issues of the hidden nature of human trafficking and unreliable data have been covered in the literature, but are there others?  Studying NGOs, studying survivors' experiences, studying perpetrators' experiences, studying donors, studying law enforcement?

    Antonio Bova · Universiteit Utrecht

    The subject of human trafficking, or the use of force, fraud or coercion to transport
    persons across international borders or within countries to exploit them for labor or sex, has received renewed attention within the last two decades. While the majority of experts on human trafficking assert that the greatest number of victims of trafficking are women and children, there is little systematic and reliable data on the scale of the phenomenon; limited understanding of the characteristics of victims (including the ability to differentiate between the special needs of adult and child victims, girls and boys, women and men), their life experiences, and their trafficking trajectories; poor understanding of the modus operandi of traffickers and their networks; and lack of
    evaluation research on the effectiveness of governmental anti-trafficking policies and the efficacy of rescue and restore programs, among other gaps in the current state of
    knowledge about human trafficking. Such information is vital to helping decision-makers craft effective policies, service providers develop culturally sensitive and linguistically appropriate and efficacious programs, and law enforcement enhance their ability to identify and protect victims and prosecute traffickers.

  • Do you agree with Stephen Hawking's recent conclusion that black holes don't exist?
    Black holes don't exist. I published this many years ago. Cantor's Universe doesn't allow the concept.

    Stephen Hawking now came up with the same conclusion. Read: http://www.spektrum.de/news/es-gibt-keine-schwarzen-loecher/1222059

    In my opinion he is right this time. What is your opinion? Was he right then or is he correct now?
    Matts Roos · University of Helsinki

    Otto, let me add a few words to Gerard's correct explanation.

    The fact that the singularity at the black hole horizon does not exist in the local frame of the spaceship indicates that the horizon is a mathematical singularity and not a physical singularity. The singularity at the horizon arises because outside it, in a region of extreme curvature, we are using,coordinates most appropriate for flat or mildly curved space-time. Alternate coordinates, more appropriate for the region of a black hole and in which the horizon does not appear as a singularity, were invented by Eddington (1924) and rediscovered by Finkelstein (1958).

  • Which is the best breast phantom for spectral CT?

    What anthropomorphic breast phantoms are available for spectral CT? Which is the best? 

  • Rafael Ibarra added an answer in Language Teaching:
    What is your experience/opinion/reference regarding code-switching in education?

    Code-switching (http://en.wikipedia.org/wiki/Code-switching) can be defined as the alternation between languages or dialects in speaking or writing in a grammatically overall consistent manner. It usually appears in 3 types, that is extrasentential, intrasentential or intraword.

    Although it was previously considered as a lower level use of language, lately it is scholarly regarded a normal, natural or even beneficial phenomenon in bilingual or multilingual environments and societies, especially in education and language teaching. There are also those who advocate that not only should it be used as a strategy (http://digitalcommons.iwu.edu/cgi/viewcontent.cgi?article=1002&context=hispstu_honproj) but also taught as a goal, for example a communicative skill or competence (http://uege5102-09m.blogspot.gr/2009/07/teaching-code-switching-in-classroom.html).

    Please share with us your experience with or opinion on or interesting references to the use of code-switching in education.

    Thank you.

    Rafael Ibarra · Universidad Nacional Autónoma de México

    In my experience taching TOEFL to college students, I have warn them - in Spanish - of the polysemic phenomenon in certain words that English language lexicographers adopted and adapted in their dictionaries, general and especialised. The most common examples are cognates and false cognates. In some other cases, I teach them to analyse, ethymologically, certain texts passages and focus our attention  in semantic boundaries key words have. I feel that if I do not do this, students simply ignore an entire lesson! Since the moment I started the code-switching, their faces show me they learn and enjoy these mentioned aspects.

  • Anyebe Onoja added an answer in Viral RNA:
    Unable to get a PCR band size i earlier got?

    I used a protocol to amplify a segment of a viral RNA.  After making cDNA, I was able to detect the positive control four times with excellent bands, each time i used the same reagents including the Taq. In all, i have thawed the reagents more than seven times but did not place on ice (on the bench for at least 15mins). Now, i am not getting any amplification again even with the same cycling conditions, primers, nuclease free water and Taq. What is likely to be my problem?

    Anyebe Onoja · University of Ibadan

    Baner and Kelly, i must add that i used cDNA which is suppose to be more stable.

  • What is the best criterion to define the presence of peripheral vascular insufficiency?

    I'm developing an experimental study in mice in which need to determine the presence of peripheral arterial disease and I would like to establish the best strategy to define this clinical situation.

    Alessandro Schiavetta · Osp.le S. Corona

    Since the patient affected by claudicatio intermittens cannot walk too much, the best strategy  I guessc ould be to set a distance that claudicants mice cannot walk, and normal mice can. For example, a "rolling wheel " test, measuring the total walking time, or something like that. 

  • How can we promote critical thinking skills across learning areas in our classrooms, if its attainable, how do we teach learners to think critically?

    looking for ways in which critical thinking as a skill can be taught to learners in our schools, across different learning areas.

    Kathy Scott-Morris · Walden University

    High level questioning:helping students find meaning and purpose in what is to be learned;

    Differentiated instruction: connecting students’ prior knowledge and cultural experiences with new concepts by constructing and designing relevant cultural metaphors and images;

    Knight, Jim.  The Big Four: A simple & powerful framework to dramatically improve instruction. The University of Kansas Center for Research on Learning. Volume 21 • Number 4 • May 2009

  • What are your thoughts on the emerging theories of learning and the role of technology?

    In the secondary classroom, there is a shift toward implementing ever-increasing amounts of educational technology into curricula. In order to do so meaningfully and to ensure successful learning, it is necessary to reflect upon learning theories. Behaviorist and Constructivist theories provide a base for much of what happens in the technological secondary classroom. These broad theories have many implications for the technological secondary classroom. It is necessary to question these implications so that those involved in the educational (and more specifically, educational technology) fields can work toward bettering education. Are there shifts happening in the secondary classroom today between these two theories? If so, what are they? Which is the more predominant in current educational practices? Is one better for use with educational technologies?

    (by Andrea K. Ebert )

    Nelson Souza · Federal University of Pará

    Off course technology helps. However according to Roxana Moreno (one of the authors of the Cognitive Theory of Multimedia Learning ) manny studies have shown that it is the quality of the methods used with a particular technology that affects student learning  not the novelty of the technology used. 

    Since the limitations of our working memory affect the way we learn, it should
    also, obviously, condition the way we teach. Cognitive Load Theory in view of these
    limitations provides several guidelines on how to design an instruction that reduces
    unproductive cognitive load and at the same time maximizes the productive cognitive
    load to make the learning more efficient. All these guidelines are based on scientific
    experiments and therefore are not mere theoretical constructs

    Because the working memory limitations are the bottleneck of learning I recommend, when teaching with technology, to cope with these limitations by using the guidelines from the following 3 theories: Cognitive Load Theory, Cognitive Theory of Multimedia Learning and Meaningful Learning theory (Ausubel).

  • David T. Risser added an answer in Ethics:
    Do you agree there is a decline in the ethical values in the field of medicine?If so what are the contributing factors?

    Ethics is an important element in the field of medicine, and it is astonishing to note that is a constant decline over the period of years, it is a must to address this issue to preserve the field from further deterioration. 

    David T. Risser · Millersville University

    Sultan Salah makes a very good point concerning the duty of healthcare professionals to be transparent in dealings with patients.  Otherwise, they risk becoming paternalistic towards patients.  Kant considered paternalism to be a particularly destructive kind of tyranny.

  • Bonnie C Carney asked a question in Skin Biopsy:
    Western Blot trouble shooting: MMP7 in skin biopsies

    I am attempting to to a western blot to look for differential MMP7 expression in skin biopsies. I know the expression is differentially regulated based on immunohistochemical evidence and want to further prove it by WB. 

    My question is, following a bradford assay, how do you know how much protein to load onto your gel in order to get visible bands. How do I know the relative amount of MMP7 in my samples? For example, I know the total protein is at a concentration of 1500 ug/mL, but how can I figure out a good amount of material to run on the gel without wasting the samples (my biopsies are very precious and we don't have a lot troubleshoot with)

    Any help is appreciated. 

    Bonnie

  • David L Morgan added an answer in Grounded Theory:
    How can grounded theory be used as a methodology for studying urban development in a region?

    It is for my PhD research. I request your suggestions and comments. My case study is a rapidly urbanizing wetland region in Kerala, India

    David L Morgan · Portland State University

    One of the first questions that would come up in a Mixed Methods Research approach is whether you are going to treat one of your methods as "primary" or dominant. In MMR notation, that would point to designs like:

    qual --> QUANT

    or

    QUAL --> quant

    In the first case, you would be using your survey as the primary part of the design for this portion of your overall study, and the prior fieldwork would help you develop the content for that survey.

    In the second case, you would be treating your survey as a supplementary study that was designed to meet the needs of your prior by adding useful follow-up data.

    These are not your only design options, but they give you a good place to start in thinking about you will connect and integrate the results from these two pieces of your total data set.

  • Marwan M. Obeidat added an answer in Words:
    Can speechlessness/silence be a better, more pungent/effective form of language than the (written or spoken) word?

    In certain circumstances, silence proves to be more meaningful/powerful a language than the spoken or the written word! Do you think this is true?

    To Professor Nelson Orringer, friend and colleague, with much admiration, to make sure what we can do with and without words!

    Marwan M. Obeidat · Hashemite University

    To Friend Ahed, yes silence is an expression. To my new, but dear, friend Marcel, your answer  (.............) is super intelligent! To both of you, I say the following: words SAY; silence SUGGESTS and, therefore, more complex-in-demands!

  • Alaa Otaibi added an answer in Crowns:
    Why is the Endo-Crown concept not widely used?

    Why is the Endo-Crown concept not widely used while studies showed a significantly higher fracture resistance and more retentive than crown over post and core?

    Alaa Otaibi · King Saud University

    Nice paper doctor Bukiet, but what about cuspal deflection after Root Canal treatment and the belief that "all endodontically treated teeth require extracoronal coverage" either ovelay or total coverage crown ? 

  • Blake Bluestein added an answer in ToF-SIMS:
    Which is the best method to prepare/wash biological coatings for ToF·SIMS evaluation?

    My primary concern is to avoid Na, since this ion is the main source of the so called "matrix-effects", i.e. it combines with other residues during fragmentation and can potentially lead to misinterpretation of the actual ion intensities in the mass spectrum. Is there any method available to wash off this ion, while preventing alterations of the coating? Thank you

    Blake Bluestein · University of Washington Seattle

    Ricardo, 

    This publication shows the preparation of NIH 3T3 Fibroblasts after rinsing with ammonium acetate and compares different analysis techniques.  

  • What publicly available datasets of annotated social interactions exist?
    I am interested in using machine learning to recognize social interaction patterns such as disagreements, and potentially use those patterns to generate new simulated interactions. I've been working with crowd sourced descriptions of social interactions, but these are more narrative and less action driven.

    Are you aware of publicly available datasets of annotated social interactions?
    Types of data that might be good candidates are annotated movie scripts or forum threads. Skeletal/gesture data could also be interesting.
    Paulo Fontainha Gomes · University of California, Santa Cruz

    For those of you interested in the Wikipedia dataset, it is described in:

    [Jankowski-Lorek et al., 2014] Jankowski-Lorek, M., Nielek, R., Wierzbicki, A., and Zielinski, K.(2014). Predicting controversy of wikipedia articles using the article feedback tool. In Proc. Seventh ASE International Conference on Social Computing.

    And available at:

    http://datahub.io/dataset/controversy-of-wikipedia-articles-using-aft

    Although not yet available online at the time of this post, I suggest contacting one of the authors, Kazimierz Zielinski, to potentially have access to an author version of the document.

    https://www.researchgate.net/profile/Kazimierz_Zielinski

  • Which method would you propose for language analysis of free text box responses?

    I have some very interesting data to look at that is from free text box responses. I would like to do some type of language analysis on this. What method would you propose I use? My thought is that conversation analysis would not work as this is not naturalistic data. A discursive psychology may also have the same issue..... any other thoughts that fit with a social constructionist perspective?

    David L Morgan · Portland State University

    I have to admit that I've never been a big fan on Conversation Analysis precisely because it downplays content to such an extent. Ii also sounds like you could have trouble with Potter's position in Discourse Analysis arguing against the study of POBAs (Perceptions, Opinions, Beliefs, and Attitudes).

    One thought is whether you are familiar with the literature on "framing" -- a useful starting point for that is:

    Benford & Snow, 2000. Framing Processes and Social Movements: An Overview and Assessment
    Annual Review of Sociology
    Vol. 26: 611-639

    A different thought that would move you very far away from CA/DA is something like the classic content analysis use of Key Word In Context (KWIC). With that approach, you would group together related search terms and then examine how they are used in actual text segments.

    Hope that helps.

  • Has any one worked on coating Carbon nanotubes with nickel by electroless deposition?

    I am working on electroless deposition of nickel on carbon nanotubes.  I am facing some problems in the process,which I am briefly mentioning  below. I would appreciate and be thankful if anyone can advice suitably.

    1. While filtering the Carbon  nanotubes after activation and rinsing stage, the filter paper (whattman filter paper in a funnel) tears when I try to scrape the dry carbon nanotubes from the paper. Is there any better method of filtering the nanotubes from the solution.?
    2. Preparation of nickel bath:    During addition of Ammonium Hydroxide (buffer solution) to the nickel bath for it to achieve a pH of around 8.2 (basic), severe salt precipitation is observed in the nickel bath, thus losing its deposition potency. How can I modify the pH of the nickel bath to basic medium without causing salt precipitation:?
    3. Also, I am carrying out the electroless nickel deposition by stirring the carbon nanotubes in the nickel bath for 30 minutes at 25 degree C. Should I carry out the process at a higher temperature (heating)?  Will heating improve the deposition rate and efficiency?

    Can anyone who has previously worked on this share their experience and references?

    Vaibhav Koushik A.V. · Atria Institute of Technology

    Dear Dr. Alicja Stankiewcz & Dr. Pavel Anatolievich,

    Below mentioned is the bath composition of the nickel bath I am using.              Hope  it answers your queries about my work and procedure followed.

    Electroless bath composition:

    NiSO4.6H20            - 25g/l

    Na3C6H5O7.2H2O - 5g/l

    NaH2.PO2.H2O         - 15g/l

    NH4Cl                          - 60g/l

    Pb(NO3)2                      - 2.5g/l

    Bath Temperature       - 25 Deg C

    pH at 25 Deg C( adjusted using NH4OH)    - 8.2

    When I add all the above mentioned chemicals and then measure the pH, it was found to be acidic. Then,I added NH4OH in small quantities till a pH of 8 was achieved. Following this severe precipitation was observed and the potency of the nickel bath was lost.

    Regards

    Vaibhav

  • Are there volunteers to be advisors if not supervisors for PhD students of developing countries?
    In developing countries, it is difficult to find mentor/supervisor for PhD students who want to pursue their research(s) in new areas such as VGI, SDI, Spatial Data Mining, Spatial Agriculture, m-governance and crowd sourcing etc. The reasons include brain drain. Therefore, to reduce digital divide in a sense, researchers/scholars/institution who can contribute to advise students especially of developing countries voluntarily are requested to help out.
    Ankush Sachdeva · Fortis Escorts Heart Institute

    good suggestion

  • Sonal Mazumder asked a question in Cancer Drugs:
    How can I do a cytotoxicity test of polymeric nanoparticles loaded with cancer drug?

    I have polymeric nanoparticles loaded with drug. I want to do cytotoxicity test. However, what concentration of drug, nanoparticles, polymer should I take? What will be my basis?

  • What is your definition of 'environment'?

    One of the popular words today is 'environment', used in quite different contexts. What is your definition?

    Joseph L Alvarez · Alpha Beta Gamut

    Environs is the surrounding area or volume. Environment includes the characteristics of the surrounding area and volume, especially those that influence a process. There are social environments, political environments, aircraft environments, and email environments. Anything we discuss or are interested in has an environment (even when we are not interested.)

    THE environment is a sacred, unattainable place that is the subject of research grants and politics. It used to be a nice place before the other guy broke it.

  • Elise Stanley added an answer in Voltage Clamp:
    How exactly does current and voltage clamping work?

    When patching a cell, what exactly is the electrode doing that "injects" current into the cell? If there's no literal injection of charge/current into the cell, how can the cell do things like accumulate charge, progressively depolarize with constant current, etc. I'm looking for a very nuts and bolts explanation of how this works.

    Thanks!

    Elise Stanley · University of Toronto

    If you want to understand this then start from the parent method - (straight) voltage clamp - as invented by KC Cole (he showed Hodgkin and Huxley how to do it on the squid giant axon and they used it to establish the ionic hypothesis of the action potential - and get a Nobel prize).

    The object is to keep the voltage constant.  To do this you need one electrode to measure the voltage and another electrode to pass current, positive or negative to stop the voltage from changing.  Thus, the current you record is actually 'feedback' current.  that's the real reason why cation currents are recorded in the negative direction - its the feedback current to stop the cell's inward cation currents from changing the membrane potential.

    However, you don't see much if you hold the voltage constant so the voltage clamp permits you to suddently change the clamped voltage to a new level (usually depolarized but it can be either direction).  This triggers voltage sensitive ion channels to open and admit ions - carrying charge.  Now the feedback loop in the voltage clamp amplifier has to pass an equal and opposite current to clamp the voltage at the new set potential.  Congrats you just did a step voltage change.

    Really that's all there is to the principle.  Another time I'll talk about capacitance because this is the property of the cell membrane that makes voltage clamp recording necessary.

    Incidentally, I was in the Cole lab (after he left).  I saved some of his equipment from being trashed (in Woods Hole).  Recently I discovered how important that was as I have established that I have the original voltage clamp chamber that Cole (and Marmot) used for voltage and current clamp recordings on the squid giant axon.  If anyone is interested I am happy to present this extraordinary piece of biophysics history (I already did to the Biophysical Society). 

    Patch clamping is voltage clamp but cleverly adapted so that you only need one electrode.  However, beware.  In actuality patch clamp really clamps the inside of the patch electrode, its an assumption that the attached cell will also be effectively clamped (generally valid for a round cell such as a DRG neuron but unlikely to be true for a highly ramified cell with dendrites).

    I hope this is useful by all means drop me a line.

  • Peter V. Zolotukhin asked a question in DNA:
    PEG DNA precipitation

    Dear colleagues, could you please kindly explain the chemistry/physics of DNA precipitation in the presence of PEG? 

  • Could anyone help me with a problem Matdyn simulation problem?

    Hello, I starting using Matdyn(matpower) in my thesis. Could anyone help me with a problem?
    How can I change the values in the event so that the buses and other branches are in three-phase short-circuit condition?( Anderson 9 bus, 3 generator system).

    Lauro de Paula · Universidade Federal de Goiás

    Hello, Yue Zhao! Please, take a look at these papers:

    1) http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5598553&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D5598553

    2) http://sem-proceedings.com/20i/sem.org-IMAC-XX-Conf-S15P04-Identification-Nonlinear-System-Characteristics-from-Experimental-or.pdf

    Good luck!

  • Sonal Mazumder asked a question in Oil Refining:
    Can anyone tell me about role of enzymes in petroleum and oil refining industries?

    I am more interested about latest papers and articles on role of enzymes in different chemical processes in petroleum or oil industries.