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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  • P. Grima Gallardo added an answer in Solar Cells:
    We would like to stablish a colaboration with a semiconductor laboratory in the field of thin films.

    We are preparing thin films for applications in low cost solar cells, however we are experimented problems for the characterization because of restrictions and unavailabilty of foreigh divises in our country (must of our characterization equipement are out of service). If you are interested, please contact us.

    P. Grima Gallardo · University of the Andes (Venezuela)

    We are working on Cu2Zn(Ge,Sn)(S,Se,Te)4 materials. We need microscopy and optical characterization.

    Many thanks for your answer.

    Pedro

  • Are there only two relativities possible-- the special and the general? Or are there more to come in future??

    We have two relativity theories so far-- Einstein's special and general theories dealing respectively with observers in inertial and non-inertial frames. There have been other relativity proposals like quantum relativity, scale relativity etc. I have made a classification of all possible relativity in general in a recent upload to RG. I find that there can be eight relativities in all -- four objective and four subjective. Do you have any more to add or is my classification exhaustive?

    Clifford Chafin · North Carolina State University

    At first I was a bit skeptical but I respect this line of inquiry now that I have seen your paper.  I read Max Jammer's book and some other philosophical themed work years ago and have always felt we have relied too much on differential geometry (manifold theory) and Hilbert spaces in our formalism at the expense of serious conceptual discussion.  

  • What is the minimum value of correlation coefficient to prove the existence of the accepted relationship between scores of two of more tests?

    Is there any guide for this, for example certain value considered week relationship, and other moderate or strong?

    Ahmad Yussuf · University of Malaya

    Thank you very much Federico for your informative answer.

  • Kunlin Song added an answer in Cellulose:
    Cellulose thin film solvent casting?

    I would like to know if its possible to prepare a cellulose thin film by solvent casting preferably using water as the medium of dispersion. If yes, what is the minimum amount of cellulose weight% that can form a film?

    Thank you.

    Kunlin Song · Louisiana State University

    Yes. You can find some papers on nanopaper from Dr. Lars Berglund's group from KTH. 

  • What are the difference between a relational database and an object oriented database?

    And how do you convert a map from a relational database to an object oriented database?

    Shashi Kumar Gadia · Iowa State University

    Here is something from my class notes in my introductory undergraduate database course. I hope it helps.

  • Thierry Chopin added an answer in Marine Algae:
    Can you help me identify the scientific name of this marine algae?

    This species was collected in Romblon, Philippines.

    Thierry Chopin · University of New Brunswick

    Sargassum as a genus. Which species is another story...

  • Recommendations for research methods textbooks?

    My team have been discussing investing in some research methods textbooks. We've got as few ideas but would be keen to hear recommendations on the following areas:

    • Qualitative methods (general)
    • nVivo
    • Statistics/quantative methods (general)
    • SPSS
    • Epidemiology (general)

    Regards

    Andrew

    Susanne I Schmidt · (bio)statistical analyses and ecological modelling

    from an ecologists' point of view: I love Quinn & Keough: Experimental Design and Data analysis for biologists - should be applicable to your questions as well

  • JC Spender added an answer in Organizations:
    What is the best book or article to read on organizational resilience?

    I prepare a new research proposal on the theme and also want students to work on this fascinating issue.

    JC Spender · Kozminski University

    Hi Gjalt,

    Interesting question - that surely begins with thinking about the 'theory of the organization' that you have in mind?

    To follow Morgan's fine exegesis, if 'the organization' is a machine - rational production function - then what can resilience mean?  It must mean the capability of the machine's designers and controllers to 're-engineer' it.

    If the organization is an 'organism' then resilience may be built into its genes - and so into the Ashby and Argyris metaphors, perhaps into Nelson & Winter.

    The authors @Laura offers all seem seem, but speak to several different assumptions about 'the organization'.

    The situation in our discipline is deeply confused by having at least a dozen different notions of 'the organization' floating around.  For some reason we (our journals and so on) have decided it is OK to theorize and pontificate on these matters without having to identify the specific theory we have adopted.

    So I would suggest reframing your question.  Resilience is going to mean different things depending on one's theory of 'the organization'.  A table of its meanings - given some of the prevailing theories - would be a great contribution.  After all, resilience is an interesting qualitative notion dealing with 'the organization's' ability to deal with what cannot be foreseen and baked into a rational design, command, and control system.  If everything could be forecast then it would be meaningless.  Conversely if nothing can be forecast before it happens then resilience can only be understood after the organization-as-organism has responded.  This is somewhat related to misunderstanding evolution as 'a theory', plainly odd given it offers no prediction of how a species will respond beyond the bald assertion that 'it will respond'.

    I recall having a public argument with Dawkins about this and, as far as I could understand what he said, he was not able to justify attaching the term 'theory' to 'evolution'.

  • Can anyone suggest a detailed, reliable and tested protocol (in situ hybridisation)?

    A tested protocol for in situ hybridisation for adrenal gland (rodent)?

    Since I tried some, but don’t work with rat adrenals.

    Mohammed Albedhawi · University of Reading

    Thank you very much. I will try them.

  • Anam Arooj added an answer in Ethanol Production:
    Any one working on "Low cost medium for bioethanol production" or low cost pretreatment techniques for bioethanol production?

    Want to get information about how to reduce ethanol production costs?

    Anam Arooj · University of the Punjab

    Just analyzing the research work that has been still done for low cost ethanol producions.

  • What is understood, in terms of biosecurity and biosurveillance, by Early Warning Systems?

    My research group and me are inquiring about this question and we want to answer some isues about this topic, in addition to this general question, we want to know:

    -What is understood, exactly, by biosurveillance?
    -What is understood, in terms of biosecurity and biosurveillance, by Early Warning Systems?
    -From the point of view of biosurveillance, scientifics and experts, what is currently the role of citizenship?
    -There are tools, apps, guidelines, etc. whereby citizenship can collaborate or "enact" as alert system?
    -Where can we find documentation about this kind of issues?
    -What is a sentinel site or a sentinel web? and how it works?
    -What is the role of Internet into this new intelligence related with detecting pandemics and acting before it occurs?

    I have some stuff written about it in my blog: http://ebaes.blogspot.com.es/

    Thanks in advance, 

    Enrique

    Sibylle Rahlenbeck · Yale University

    Hi Enrique,

    As you mentioned, the term ‚biosurveillance‘ is closely related to the term ‘bio-monitoring’, in which monitoring is less regular than one would expet it to be in a surveillance system. Originally, these terms were coined about 40 years ago, when environmental concerns grew because of the ever occurring industrial pollution. Standard books of the matter should give you an overview about the terms applied.


    Are there tools where the citizen can contribute?
    Usually, every citizen can forward his/her concern to the appropriate parties, the national or international bodies concerned with the issue. In the U.S. this is certainly the EPA.
    A sentinel site is a reference site being used usually on a national base. Look at what the tropical docs say about sentinel sites for their research:
    http://en.wikipedia.org/wiki/International_Society_of_Travel_Medicine

    wish you all the best with your endeavor,

    good luck!

  • What are k1, k2 and k3 parameters in PRSV2 equation of state for monoethylene glycol (MEG)? Are there any references for these parameters?

    I need k1, k2 and k3 parameters in PRSV2 equation of state for different materials including gases, water, alcohols and glycols. In fact, i am looking for appropriate references that include characteristic parameters and adjustable interaction parameters in PRSV2 equation of state.

    Mariano Pierantozzi · Università Politecnica delle Marche

    I don't think that exists this parameters for this excellent equation.

    If you find it, please tell me.

    Mariano

  • Rachid Rouabhi asked a question in Enzymes:
    Can any one difference me between the isolation of enzymes from mitcochondria and peroxysomes?

    can any one difference me between the isolation of enzymes from mitcochondria and peroxysomes?

    even in isolation

  • What are conditions during transport of milk samples to be analysed by milkoscan technique?

    My work involves transportation of milk samples from the farm to the lab. I would know, how should I conserve my samples, knowing that, the lab is approximately 3 hours far from the farm, and sometimes, I'll have to conserve it during the night when samples are taken late after noon (analyse are done to determine fat and protein content in the milk)

    Vesna Karapetkovska Hristova · St. Clement of Ohrid University of Bitola

    Hello d-r Hossem

    My suggestion is to use one thermally insulated wooden box with ice and put the sample bottles or vials (we are using according to Chalmers) and nothing more, no money spending :)

    For chemical examination of milk,  this sample conservation during transport is correct but for microbiological analyzes not.

    Best

    Vesna

         
  • Rachid Rouabhi added an answer in Animal Models:
    Can use i.p. injection for up and down LD50 measurement?

    Every articles that i have studied for assessment of ld50 by up and down procedure have used oral route for animal treatment. I wanna know if it possible to use I.P route for assessment of ld50 through up and down procedure?

    Rachid Rouabhi · Université de Tébessa

    dear Abolfadhl

    of course you can do it but be carful of the dose and the waiting time >2 days

    http://www.ncbi.nlm.nih.gov/pubmed/3987991

    have  a nice day

  • Lall B. Ramrattan added an answer in GDP:
    What is the prime difference in PPP GDP and Nominal GDP?

    Bangladesh is listed at 36th best country when it comes about PPP GDP but 155th when nominal GDP is considered. So, if I want to know the real economy state of a country, which one should I look at? The nominal GDP or, the PPP GDP? 

    And what other factors should I look at if I want to know about the economical prospect of a country? 

    Your valuable answers will be great to know. Thank you in advance 

    Lall B. Ramrattan · University of California, Berkeley

    The question on PPP comparison is complex, depending on the data base you are using. The founders of the Penn World Table have researched this method thoroughly. I attach one of their articles.

  • Omar Marchant added an answer in Hydroponics:
    Do you know suppliers providing hydroponic culture containers with grooves for holding plants?

    I would like to do some hydroponic experiments for cowpeas. I need large containers  to carry out hydroponic cultures. Can anybody provide me any information about suppliers from whom I can get the containers?

    Omar Marchant · islam

    salaam, bismillah you may want to consider a floating raft system. such systems are being used to good affect with lettuce.   

  • Universe is static!!! Yes or no?

    Space of Universe is static! Yes or no?

    Question: Are there any observations that do not fit into the model static space of Universe, are there any theoretical obstacles to the existence of such a model?

    I assume that the Universe is eternal, infinite and static, it is not expanded and not curved, it is possible to construct a preferred inertial frame of reference in which the CMBR is most isotropic. The matter in this space evolves, but the average density of matter and energy (in large enough volumes) fluctuate within a rather broad range.
    The light in this model is "tired", the speed of light depends on the optical density intergalactic medium. Gravity is also "tired" t.i. weakens a little faster R2. The energy of destroying matter goes into the surrounding vacuum. The excess energy from the vacuum give rise to new particles of matter.

    I state that all the observed cosmological effects can be explained in such a Static Model of the Universe.
    See attached "Basic_Cosmological_Formula_1_En.pdf"

    Dear colleagues, I do not ask, what are the problems faced by other theories (though I would be interested in your opinion on that. The General theory of relativity is not applicable to the entire space of the Universe).

    Erkki J. Brändas · Uppsala University

    Dear all,

    I am sorry to “contaminate” your thread with this discussion. However, I believe that my analysis of Johan’s callous critique of contemporary physics does reflect some vital aspects of the difficulties involved, in order to generate new ideas that should not be in conflict with fundamental mathematics and the consensus interpretation of physics

    Johan,

    There are several problems with your theory, in which you for the most part adopt Maxwell’s equations as a sole theoretical basis. In particular you do not distinguish the dynamic features and the statistical properties between “particles” with rest mass, like electrons, and entities with zero rest mass, like photons.

    You did not address my detailed complaint above where I compared your equations for photons and your derived equation for matter waves with 𝛽=𝜈/c≤1. You cannot do this mix because, if this would be OK, then your heralded radio engineers would be Star Trek stars carrying out teleportation!

    Another problem appears in connection with your Lorentz transformation in the basis entity  x and ict. How do you normalize these vectors?

    One possibility is of course to use a standard positive definite metric, which implies that x2+c2t2= 1 (or finite), which authorizes the concept of unitary transformations.

    However your physical application concerns the norm x2-c2t2= 1. This imparts a non-positive definite metric with crucial consequences for the rotation matrix, that we denote by the matrix L, cf. Eq.(9) in your paper “On the derivation of the Lorentz-transformation”. 

    The metric we normally employ (without thinking) is the metric matrix 𝚫=I with I being the unit matrix. However with a non-positive definite metric, like the one you must use in relativity, confers a 𝚫np with the 𝚫22 element replaced by -1. Hence you should represent the rotation by (𝚫np)-1L. This matrix is complex symmetric and has a Jordan block singularity corresponding to 𝜈=c.

    What I am saying here is that you are misusing mathematics and if your math is wrong your physics would have an infinitely small probability to come out right?

  • Varshika Singh added an answer in Bioinformatics:
    Can anyone suggest good sandwich phd program in bioinformatics?

    for 6months to 1 year time duration

    Varshika Singh · Banasthali University

    shawin karim hmm got your point.

  • Is the firm a middle-number system?

    Following Weinberg ("An Introduction to General Systems Thinking", 1975) and Allen and Starr ("Hierarchy: Perspectives for Ecological Complexity", 1982) definition of middle-number systems as those with too many elements to be examined one-by-one and with too few elements to express them in statistical averages, do you think this could be applied to the firm?

    Carlos Eduardo Maldonado · Universidad del Rosario

    Dear Francisco, nice question. Let's firstly take into account that nearly all around the world, in each country large companies are a huge minority, and by and large, most companies are SMEs. Therefore, the question is to be framed accordingly.

    Generally speaking, one culd answer affirmatively. However, as we take a more coarsed approach, the answer is to be nuanced.

    Not to mention -going back to the justification of the question, a (in my own view) very serious problem, namely: even though close to each other to some extent, systems ascience is, at the end of the day, quite different from complexity science. From this standpoint I would dare to say: within the context of system science one can raher safely anser: yes.

    However, as we focus on complexity science, the answer becomes certainly much more dubitable.

  • What information transmits excited neuron-detector? What sense is this information?

    If we consider the neuron as an information system, its response to the same input actions should be invariable. What does the variability of the studied characteristics of the reaction interneuron to the same stimuli? Could it be that the response of the neuron-detector says only that he at this time excited with a certain level of excitement? Obviously, the neuron is highly adaptive system. However, such systems are not highly accurate. There is a contradiction in the consideration of the neuron at the same time as a highly adaptive and precise information system.  

    Federico Bugnoli · University of Verona

    Speaking about "perfect adaptation" seems too naive... Maybe the [valuable] information is not encoded by a single neuron, but rather a group of cells is responsible of its transmission/encrypting. In this case, if the unit itself behave inaccurately (there is no direct/estimated relation with the right result), at a higher level (i.e. swarm intelligence) the correct information is preserved - it may be that the way in which the flow of information is treated within the brain has similarities with error-correcting codes: even if a local misadaptation occurs, neuroplasticity provides an alternative [non-linear] path to what it was meant to [on a higher level]. 

  • Scott Newman added an answer in Genome Annotation:
    How do you create a custom genome browser to which you can align unique (CNV mutated) sequences for ChIP-seq?

    Hi Everyone.

    I have performed ChIP-Seq on individuals with a CNV mutation and normal (do not have the CNV mutation) and have the sequences from both sets. If I align the sequences of the CNV mutated individuals to a normal reference genome I won't be able to align part of their unique sequence (the hg19 genome does not have their CNV mutation). Is there any software that helps you to create a reference genome with an annotation for a specific mutation? In that way I can align my unique ChIP-seq data to a specifically annotated reference genome.

    Scott Newman · Emory University

    Hi Asim,

    Is your working hypothesis that people with the CNV will have relatively more (or less) binding of a particular transcription factor or chromatin modifier within the CNV region? Secondly, how big is your CNV. Is it kb or Mb in size or is it a small polymorphism in the sequence of a promoter (or enhancer or whatever you're interested in)? This could dictate your alignment strategy.

    Thanks

  • Kuczyński Jarosław added an answer in Hemostasis:
    Is PS phosphatydyl-serine important in hemostasis?

     
    PS is fofolipidem cell membrane and in contact with TF Tissue factor involved in the initiation of coagulation (enhances the effect of the cofactor). Does PS - do the same factors can bind and activate a cascade of plasma clotting?

    Kuczyński Jarosław · Państwowa Wyższa Szkoła Zawodowa- State Higher Vocational School in Suwalki

    Thank you very much. I just found information about PS work Microparticles in Hemostasis and Thrombosis A. Phillip Owens III, Nigel Mackman.

  • Abdulghefar Kamil Faiq added an answer in RG score:
    RG score and impact points should be considered by Universities for selecting faculties?
    It is always a tough task for universities to select the best faculty. RG score and impact points of scholar may reflect underlying talent and potential of the candidate. So, RG score and total impact points may be used as criteria to select the best faculty by universities.
    Abdulghefar Kamil Faiq · Salahaddin University - Hawler

    Dear Ljubomir Jacić thank you very much for your notation , but  since about one year i followed up the total Rg in my university, it was approximately  the total of rg's of the members , but since about two or three months (i am not sure, its not updated i see that Rg's of all institutions in researcher gate is not affected by the members). My remark about what you   have mentioned above, i think its valid exactly in the total impact point of the institutions .

    regards

  • Kaoru Aou added an answer in Glass Transition:
    Why does DMA Loss Modulus increase and decrease?

    Hi,

    I understand the loss modulus increases as the polymer approaches the glass transition temperature, but why does the loss modulus decrease after the polymer temperature is higher then its glass transition temperature?

    Kaoru Aou · Dow Chemical Company

    So G" (T) = Stress(T) / Elong(T) * sin delta (T).  Well, the storage modulus is G' (T) = Stress(T) / Elong(T) * cos delta (T).

    So the argument about stress decreasing with temperature, while partly right, does not address the question fully, since the argument equally applies to both G" (loss modulus) and G' (storage modulus).

    What we need to pay attention to just as well is the loss tangent ("tan delta").  When you have a polymeric (either thermoplastic or thermoset), and your temperature exceeds the glass transition temperature, then you have a "rubbery" material with crosslinks (can be physical, like entanglements for thermoplastics and hydrogen bonding for polyurethane thermosets;  or can be chemical, as in vulcanized rubbers).

    So a polymeric material, which is very viscoelastic in the glass transition zone (and therefore its "tan delta" shows a peak), becomes much more elastic above the Tg, where the tan delta decreases substantially.  Since G" = Stress / Elong * sin delta ==> a decrease in tan delta = decrease in sin delta, so G" decreases.  So that is the fuller picture.

    ---

    Additional note: if you were to take a polymeric liquid with molecular weight that is substantially lower than the entanglement molecular weight (in which case, you might refer to it more appropriately as an oligomer), and do a DMA experiment, you will find that your G" will keep increasing as you go above the Tg [don't ask me why, but I actually did a test like that to convince myself one time what I already should have known!]   So the tan delta decreasing after the glass transition, is seen with rubbers and not liquids.  This is a key difference between polymeric glasses (glass-rubber transition) and small molecule glasses (glass-liquid transition).

  • How best to detect oxalate and bicarbonate?

    Hello, 

    If I have a complex reaction mixture with several ionic and molecular species, what is the best way to quantify oxalate and bicarbonate? This could be in water, and/or organic solvents like acetonitrile or DMF. I have heard of people using Ion Chromatography and was considering trying get access to one at a nearby university, but if there another way I would love to hear it! 

    Thanks,

    Kyle

    Matthew D. Sampson · University of California, San Diego

    Kyle, 

    I was also going to suggest quantitative 13C NMR with a standard for oxalate and for carbonate. I only have experience trying to detect them qualitatively, but for that, we usually do 13C NMR with standards along with FTIR with standards. 

    I would make a calibrate curve for 13C NMR with known concentrations of the standards, then run your sample and compare the integrations.

    Be careful with oxalate though because I think that can decompose into CO2 and formate. Might want to look into this.

  • Zlatko Nedić asked a question in Soil Ecology:
    Is it possible to analyze the soil ecological condition by the analysis of edafobionta?

    I would like to contribute some kind of ecological assessment of soil, and ecological analysis of cratures from a soil sounds good, but I am not sure, does it possible to create some conclusion based of analysis of mentioned organisms? If you have some similar articles, please, recommende me! I would like to hear your opinion.

  • Xilin Zhang added an answer in EEG:
    How one can distinguish the activity based on EEG signal?

    My question which portion of brain is more active during different activity. Is there any analysis available. if any share 

    Xilin Zhang · National Institutes of Health

    please see the paper: Garcia, J. O., Srinivasan, R., & Serences, J. T. (2013). Near-real-time feature-selective modulations in human cortex. Current Biology, 23(6), 515-522.

  • Is a rigid rod moving perpendicularly to x axis (in the standard Special Relativity axes convention) parallel to the moving system x’ axis?

    I had a few discussions of this problem and most people maintain the moving rigid rod always parallel to x is not parallel to x’ even though it is said x' axis is co-linear with x axis which is counterintuitive.

    I maintain that parallelism is preserved by the assertion of possible coincidence and co-linearity of the rod with x axis which is co-linear with x' while the STR formulae after Lorentz transformation seem to indicate otherwise.

    Any thoughts/comments/discussion in that matter will be highly appreciated as they are vital to my research.

    Johan Frans Prins · Sage Wise 66 (Pty) Ltd

    Walter,

    You are arrogant to make such a serious allegation without knowing where I come from. YOU are the one who have pre-conceived ideas and who is closing down your mind since you dare not let go of your pre-taught ideas.

    I have taught STR for mnany years and also taught the claptrap that you want to believe until I had to find out the difficult way that it is absurd nonsense. I could then, just like you, have blindly fought against logic. But being a REAL scientist I kept an open mind. 

    It is time that YOU should read those who can help YOU to see how absurd your understanding of STR is. May I suggest that you read Herbert Dingle's "Science at the Crossroads" which you can download from the internet. Dingle also taught STR for many years and even wrote a textbook on it which was highly recommended by the mainstream physicists including Einstein. He then also eventually realised that absurdities just cannot be real physics. It is YOU who need help: And plenty of it.