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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  • Eve Carlson added an answer in Clinical Psychology:
    What are the cut scores for levels of severity on the clinician administered PTSD scale (CAPS)?

    Thank you.

    Eve Carlson · U.S. Department of Veterans Affairs

    You are most welcome!


    Eve

  • Alberto D'Amore added an answer in Viscosity:
    What is the relation between polymer viscosity and oil industrails?

    What is the relation between polymer viscosity and oil industrials.

    Alberto D'Amore · Second University of Naples

    Hi Karar,

    The viscosity of polymers is regulated by secondary interaction like ordinary liquids. However since the molecular weigth  of polumers  is very large (sometimes of order of several hundred thousands Daltons) the topological constrains (the entanglements) give rise to the peculiar visco-elastic response of polymers to shear flow (in general, polymers show shear thinning effect, namely the apparent decrease of viscosity with the intensity  of shear flow) .

    Oils may have much lower molecular weigth, thus the viscosity is only regulated by the intensity of secondary interactions between molecules. When oils are modified with polymers the appearence of viscoelastic phenomena is visible at high shear rates.

  • Seyed Amin Mousavi added an answer in Cement Mortars:
    How to achieve a high early strength for cement mortar?

    I am aware about autoclave, heating, using accelerator agents, Type III cements, polymer modification, and lower W/C ratios. But I am wondering if you can introduce other techniques, as well.

    I am referring to achieve a compressive strength of at least 20 MPa in 1 day or less.

    Seyed Amin Mousavi · University of Tehran

    There are some contradictional reports within the literature. Most earlier studies suggested that silica fume has a negative effect on the early strength. In my own experimental program, I have measured reduced early strengths due to silica fume. In other hand, I've seen some studies suggested that silica fume had increased the early strength....! It seems there is no uniform picture about this story yet.

  • Doug Leeper added an answer in Publications:
    Which are the aspects for the selection of the LED lamps for it installation in the publics ilumination?

    I will study the methods for the selection of the LED lamps for installation in the publics ilumination in the Huambo streets.

    Doug Leeper · Electrical Research

    These additional areas on the site may be useful:

    http://energy.gov/eere/ssl/gateway-demonstrations

    http://energy.gov/eere/ssl/caliper-testing

  • F. Vissani added an answer in Neutrino Physics:
    Has cosmology diminished neutrino masses?

    When we compare various cosmological determinations of neutrinos masses, Primack et al, 4.8 eV (1994); Allen et al, 0.6±0.3 eV (2003); Battye et al, 0.3±0.1 eV (2014) and finally Palanque-Delbrouille et al, 0.02±0.06 eV (2015), we see that the results have kept changing in the course of the time; moreover, they contradict each other.

    However, the most recent one, appeared after Planck data, is quite impressive and agrees with the conventional picture of the neutrino mass spectrum, expected to obey a hierarchical pattern, and that implies the lower bound of 0.05 eV.

    Evidently, this result is of great importance for the search of neutrino mass in laboratory. Do you consider the new result from cosmology reliable? Which systematic effects could threaten it? And, assuming it is correct, how could we test it in laboratories?

    Reference to the new work:

    F. Vissani · INFN - Istituto Nazionale di Fisica Nucleare

    Dear Biswajoy,  the limit that Katrin can attain is 0.2 eV each neutrino; the sum (=the quantity probed in cosmology) is about 0.6 eV. Now if the measurement is correct, the bound is 0.02\pm 0.06 eV so it is about one order of magnitude tighter. This is a very good reason to discuss whether these limits are correct or not.

    For comparison, the largest scale of oscillation is about 0.05 eV (in the sense that its square gives the "atmospheric" mass difference squared, about 2.5 10^-3 eV2). What I am saying is that the case of "normal" mass hierarchy, where the sum is larger or equal to this quantity, is still OK, whereas the inverse hierarchy that gives a sum larger than 0.1 eV starts to be probed by these new cosmological analyses!

    Very similar considerations apply to the hypothesis of new sterile neutrinos. In order to contribute to neutrinoless double beta decay process, its mixing and its mass should not be small. But in this case it is brought into equilibrium: The point is that oscillations, alone, are able to bring neutrinos in equilibrium, see e.g. the 1st attached publication. Thus, the cosmological limit does apply. In particular the neutrinos that could explain LSND are ruled out. 

  • Akira Kanda added an answer in Theoretical Physics:
    May gravito-electromagnetism be an alternative to Einstein's theory of general relativity?

    Gravito-electromagnetism (GEM) describes gravitation starting from the idea (suggested in 1893 by Oliver Heaviside and further developed by Olev Jefimenko) that there is a formal analogy between the gravitational and the electromagnetic phenomena.  This implies that - relative to an inertial reference system O - a gravitational field is characterized, in analogy with an electromagnetic field, by two vectorial quantities: the gravitational field Eg and the gravitational induction Bg.  The spatial mass destribution is the source of Eg  and the motion of the masses relative to O that of Bg

    According to GEM, a gravitational field is just like an electromagnetic field (Maxwell's equations) mathematically described by a set of four partial differential equations, the GEM-equations.   They describe how Eg  and Bg   vary in space due to their sources and how they are intertwined.  The action of a gravitational field on particles is described by a law analogous to Lorentz's force law: the force law of GEM.

    It has been shown that GEM can explain a number of phenomena (precession of planets and binary pulsars, gravity probe B experiment, ...) that are inexplicable in the context of Newton's description of gravitation what makes that GEM can be considered as a possible alternative to GRT.

    In line with the original idea of Heaviside GEM can be seen as an extension and a refinement of the "classical theory of the gravitational field", an extension that - besides the effect of the spatial distribution of the gravitating bodies - takes into account the effect of their motion.  GEM can theoretically be founded and explained by the theory of informatons. (https://www.researchgate.net/publication/268576021_GRAVITO-ELECTROMAGNETISM_EXPLAINED_BY_THE_THEORY_OF_INFORMATONS?ev=prf.pub)

    Let us still mention that GEM has been discussed within the context of general relativity by a number of authors and that it has been shown that  the GEM equations can be derived in the weak field approximation of Einstein's description of gravity.

    Akira Kanda · University of Toronto

    Daniele,

    As far as I can say, empiricism is the most primitive crude metaphysics we mankind ever developed. This manifests in the so calls American mathematics where they never teach how to formulate a mathematical theory so  that students can learn how to prove mathematical theorems. They instead have such thing as "proof by examples".

    The post WWII domination of American science destroyed the entire tradition of science and we are now where we are. This is why Prof. Peleman gave a stern warning rejecting the offer of American Fields Award for solving the Poincre Conjecture. He stated that the conjecture is of no mathematical importance. He rejected the offer of one million dollars monetary award warning us that the commercialism, money worshiping of American science is destroying the world science. 

    Going back to the issue of metaphysics, the reason why I declare that the empiricism is the lowest form of metaphysics upon which we build our science to understand our world is because from only finitely many data they bang out laws of physics, aka induction upon finite data as Hume put it. This is to say that such laws are verified b y only very limited number of experimental data. Think about it. Assume that we have a sequence of digits. By looking at only finitely man initial part of the sequence, can we determine if the sequence converges not a real number or not? In mathematics, except some die hard  intuitionists with some incomprehensible intuition, we say no!

    Think about the aritthmeticof natural numbers, we define natural numbers recursively as follows:

    1. 0 is a natural number. 
    2. If n is a natural number then n' is a natural number
    3. These are precisely natural numbers. (completion)

    This recursive definition of natural numbers yields the following mathematical induction:

    "If P(0) is true" and "for any natural number n, P(n) ->P(n'), then P(n) is true for all natural numbers n". 

    Here unlike the "induction" in empirical science, we do not deduce that P(n) is true for all natural number n as P(n) is true for some finitely many natural numbers. The mathematical induction is valid just because we defined natural numbers in the way we did above. The completion clause allows us to have the validity of the mathematical induction.

    So, induction in mathematics such as mathematical induction or transfinite induction is valid because the induction covers all cases of numbers considered. 

    Compared with these mathematical inductions, the induction in empirical sciences cover only a terribly small fraction of examples.  This is totally invalid. May be 500 years ago, this kind of fallacy was still OK. But never now. Empiricism is bunk. 

    In 

  • Shawn Booth added an answer in Correlation Analysis:
    How can one make sure that his/her sample already contains sufficient data for a meaningful correlation/regression analysis (in ecological studies)?

    I am looking at temporal changes in the vegetation cover in an area and aiming to examine these changes against several potential drivers. I have 6 points in time for my temporal studies and am now wondering if the outcome of correlation analysis of 6 points would be meaningful. 

    Shawn Booth · University of British Columbia - Vancouver

    A power analysis to see what the sample size should be to detect the effect you're looking for, and this would help to explain your conclusions; oh, I just noted its in the above reply. However, you could also see from your sample size what type of power your analysis/conclusions have.

  • Billel Alirachedi added an answer in Simulink:
    I need to make a feed back linearisation of this equation under matlab simulink ?

    alpha = A x(t) with A is a Matrice 3*3 and x(t)=[x1;x2;x3]

    aplha = a1 x1(t) + a2 x2(t) +0;x3(t)

    Billel Alirachedi · Université 8 mai 1945 - Guelma

    Hi

    thank you for your interest,yes alpha is vector equal to the product of the matrix A 3.3 and the vector 3  x(t)=[x1;x2;x3]

    best regards

  • V. Divakara Rao added an answer in Mathematical Methods:
    Numerical modelling of structural controls on gold-bearing quartz veins. Does this seem attractive for a collaborator?

    Numerical analysis

    Geo-sciences computational methods

    Mathematical methods in Geology

    V. Divakara Rao · National Geophysical Research Institute

    Dr.D.d.sarma of NGRI (Retd) has done some interesting work on statistical controls on gold bearing ,Kolar gold mines and the data may be there in NGRI. You can add it for your R&D

  • Maria Gessica Ciulla added an answer in Powders:
    What is the difference between molecular sieves powder 4A and beads 4A in anhydrous O-glycosylation reactions?

    Maybe larger surface area of powder? Thanks

    Maria Gessica Ciulla · Università degli Studi di Urbino "Carlo Bo"

    Thank you. But  does it also adsorb  both the solvent and the water more quickly?

  • Barbara Lauridsen added an answer in Educational Theory:
    Can open-book tests/examinations address the problem of cheating? How about allowing students to 'Google' answers?

    The embedded post from Faculty Focus points out that students may be tempted to cheat in instances where responses to a question can be easily 'Googled'. It is suggested that open-book tests, including challenging application questions that relate directly to the course material, may help overcome this problem.

    Some even believe that students should be allowed to 'Google' information during examinations, for instance, because they have to demonstrate digital literacy (an opinion expressed in the post from The Guardian).

    Which of these approaches (if any) are acceptable? What would serve as  guidelines for good practice if either of these approaches are incorporated in teaching and learning? Would a particular approach be acceptable in different fields or at various levels of study? 

    Barbara Lauridsen · National University (California)

    Reply to George Stoica ...

    Discrimination is key if a search for a "right" answer, in memory, notes, electronic books or relevant Internet sites is a critical skill... "to find those formulas, or algorithms, guidelines etc, apply them properly, and perform the required computations". Wiki glossary sites obviously are trivial compared to those which are offer professional's guidance on computations etc. Discerning the fit of an answer to the situation is the essential talent that we enforce.

    To interpret a question and to knowing where to find a reliable answers (plural) is an idea that resonates.  Textbooks survive as a reliable source only for awhile after graduation.

  • Helena Pestana added an answer in ROC Analysis:
    How can I compare 2 AUC values of different parameters of the same sample group (ROC analysis)?

    I found a program to compare the AUC values of different sample groups (independent test) but not for the AUC of different parameters in the same sample group. Does anyone know of a program (freeware or online) or a way to calculate the statistical difference of these 2+ AUC values with SPSS?

    Thank you very much in advance!

    Helena Pestana · ISCTE-Instituto Universitário de Lisboa

    Dear Huda,

    I bought  the book via amazon. It was very easy and rapid...

    But you could by it via link from ODA journal...could be less expensive.. If i was you I would ask him...

    I saw this for you:

    Contact Us

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    The Journal

    All the best for you

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  • Andrew Sulya added an answer in Protein Profiling:
    Is there any software to align electropherogram peaks?

    Does anyone know any software that can align the peaks of an electropherogram?

    I use the Experion Capillary Electrophoresis system to obtain a protein profile of saliva samples but i have some trouble comparing profiles from different samples because the obtained peaks are frequently unaligned.

    Thank you!

    Andrew Sulya · CMC Biologics

    We use a 10 kDa internal standard in each electropherogram and calculate the Relative Migration Time for each peak of interest.

  • Kulothungan Ganapathy asked a question in Aromatase:
    Where can i buy Aromatase enzyme (contorl ) for Western blot?

    Suggest places to buy Antibodies as well

  • Jacqueline Lane added an answer in Cancer Cell Line:
    How can I transport cell lines from one country to other?
    What is the best method to transport the cell line? What are the legal issues, courier problems, cargo issues in airports?
    Jacqueline Lane · Massachusetts General Hospital

    If you have the service, i think World Courier refreshes the dry ice during shipment.

  • Andrés Guerrero added an answer in Creatine:
    Will urea, creatine and creatinine bind to a C18 column?

    Hi there, I'm trying to separate these compounds (urea, creatine and creatinine) from a mixture of peptides. I'm wondering whether these compounds will bind to the column, too? I'm hoping they won't so that they won't affect the binding capacity. Also, does anyone know a good way to determine whether a compound will bind to a C18 column without having to do an experiment with a standard--i.e. is there some sort of number that can be used, some polarity threshold? 

    Andrés Guerrero · University of California, Davis

    Aurea, totally true but they are using isocratic conditions with a mobile phase composed by more than 99% aqueous buffer and these compounds elute in a few minutes. For preparative purposes, you can easily apply David's mixture to a C18 cartridge and wash away (or collect) urea, creative and creatinine with a few volumes of 97% H20 and 0.1% TFA with minimal peptide lose. 

  • B. A. Buhari asked a question in Reverse Engineering:
    How can we measure the performance of reverse engineering?

    The performance of reverse engineered system

  • Paul Rutland added an answer in Plasmids:
    Could someone help me with my transformation issue?

    I am writing to you regarding a problem I had with my sequencing results. Allow me to describe the situation for you.
    I cloned 79 pb of MPITS1 into plasmid TOPO10 and the colony-PCR results were positive. But the issue is that when I send it for sequencing, I got the results with double insert, that means for me that my sequence of interest was twice inserted into my vector which is pcr4-TOPO. I repeated it 4 times (The vector weight is 10ng/µl with 413 pb and my insert is 44ng but I used 1:5;1:10 then I diluted until I got 1ng/µl and I used 1µl of insert for 1µl of vector), unfortunately the results were the same. So, I decide to contact for  looking into why my experimentation is not working. I was hoping someone could share some insight as to whether I should change something or not. Also, I was wondering whether I misread the results. I would be grateful if someone could find time to answer my question.
    Looking forward to your reply,

    LA

    Paul Rutland · University College London

    i would try diluting the insert further so that it is more likely to find plasmid to ligate to rather than other insert molecules and pcr across the insert as a quick method for determining the insert size eg plasmid dna +79bp or plasmiddna +158bp  by direct pcr of a scrape of positive colony without purifying the dna just a few cells in the pcr mixture

  • María López Martín added an answer in Radioisotopes:
    How can I dilute a highly enrichment 15-nitrogen samples?

    I have samples of leaves, roots and soil highly enrichment but I want to dilute the concentration of 15N in order to be able measure them in the isotope ratio mass spectrometry.

    María López Martín · Spanish National Research Council

    Hi again,

    Elisabetta Tomé, Which is the dilution equation for the calculus? Because I would not like to have a high enrichment in the final mixture, then I would like to know in advance more or less how much mg I have to weight up from enriched and not enriched samples.

    Thanks

  • RAMA SHANKAR YADAV added an answer in Questionnaire:
    How can I adopt a scale in Indian context which is already established in Western Context?

    I am planning to develop a questionnaire instrument which needs to be adopted in the Indian context, the scale is already established in the Western context. What are the steps involved? Can I add items to the adopted scale, if yes how?

    Thanks in advance !!

    RAMA SHANKAR YADAV · Indian Institute of Management

     Thank You Devi Sir and Abebayehu !

    It is really insightful. Thanks again !

    Regards

    Rama

  • Pere Freixa added an answer in Digital Culture:
    What is digital culture? -- values, beliefs and artifacts?

    I am  been attempting to define "digital culture"?  Typically,  I might think about culture as a set of values, beliefs, artifacts, rituals and perhaps other characteristics that distinguish that culture from others.  Help,  how do you distinguish or define digital culture?

    Pere Freixa · University Pompeu Fabra

    Hi, Charles,
    I think some years before digital revolution, cybernetics defined a new knowledge area, as a result of confluence of different disciplines: physics, mathematics, psychology, etc. Norbert Wiener's "Cybernetics" remains as source of inspiration for many contemporary authors: http://en.wikipedia.org/wiki/Norbert_Wiener

  • Emmanuel Yujuico added an answer in Marketing Strategy:
    What is the relation between football clubs and social media and how clubs used it?

    With an ever-growing number of people using social media, world-famous football clubs such as Manchester United or Real Madrid have been posed with the challenge of monetising their large fan base. It has also created new opportunities for football clubs to implement innovative marketing strategies beyond the scope of social media. 

    Emmanuel Yujuico · The London School of Economics and Political Science

    My take is that it's still early in the game so to speak in utilizing social media. Yes, most of the big clubs use the likes of Twitter and Facebook nowadays--especially those in the Premier League and La Liga--but they are still trying to find ways of monetizing their user bases. This will involve the use of more sophisticated data mining techniques as they go forward. Or, in contemporary marketing-speak, finding patterns in "Big Data".

    See a 2014 FT article in the link below as well as the attached article on "A Study of the Use of Social Media Marketing in the Football Industry" which you may be able to use. Surprisingly, there is not much empirical research on this aspect of sports marketing yet, so it may be a good area to investigate--especially if you are able to obtain usage metrics from these clubs.

  • Abdulatheem Mushtaha added an answer in Geomorphological Mapping:
    Is there any systematic classification for genetic morphology of landform?

    In term of the geomorphological mapping, the landform unit must refers to a proper classification. For geological purpose, the unit must explain the genesis which form the unit.

    Abdulatheem Mushtaha · Al-Azhar University - Gaza

    Also you can read tgis article,

    http://www.geomorphology.org.uk/sites/default/files/geom_tech_chapters/3.6.1_KarstLandformClassificationTechniques.pdf

  • Ronán Michael Conroy added an answer in Statistical Tools:
    How do I correlate a disease state with a diagnostic value using statistics?

    I have put a numerical value (arbetiary unit) for disease state instead of zero (for unaffected state). On another panel I have cholesterol levels. I would like to know as what statistical tools can be applied to determine any kind of relationship between the disease state and the cholesterol levels before stating that both of them are independent of each other. Please suggest. I have all the data in excel files. Thanks

    Ronán Michael Conroy · Royal College of Surgeons in Ireland

    The association of cholesterol with retinopathy has been studied for years. What are you bringing to the area that's new?

  • Ying Henderson added an answer in FFPE:
    How do I improve RNA extraction for RT-PCR from FFPE tissue?

    Thanks for the reply. I followed the protocol same as mentioned in the Qaigen kit,but was not able to get any resuilts. In the initial samples I did not crushed the samples and the incubation time was same of 15 min each at 56 degree followed by 80 degree while I did lysis with PKD buffer and Proteinase K. Any other suggestion to improve the results.

    Ying Henderson · University of Texas MD Anderson Cancer Center

    I used recoverall from Ambion.  Worked great.  You may not get a lot of RNA but enough for RT.  Make sure the final volume is small.  Good luck!

  • Jerzy A. Sawicki added an answer in Radiation Physics:
    Where do the electrons go after alpha decay?

    In alpha decay process,parent nucleus decays by emitting alpha and daughter nucleus. However, It is the decay that happens in parent atom. Is it correct? If it is correct, which means that the daughter "atom" remains two extract electrons after alpha decay. Where would the two electrons go after alpha decay? It confused me a lot.

    Jerzy A. Sawicki · University of Victoria

    In the context of this discussion it is worth seeing the theoretical paper titled "Electron shell and the a-decay", by Sergey Yu. Igashov and Yury M. Tchuvil’sky.  They calculated the difference in the a-decay of a long-lived heavy bare nucleus and same nucleus with the shell as being below 1%. Thera are other ideas and references there.

  • Amaechi J. Anyaegbunam added an answer in Earthquake:
    Can the fundamental frequency of soi-structure system be greater than the dominant frequency of input earthquake motion in Rayleigh Damping?

    I am performing Transient Dynamic Analysis of a 3-storey structure with isolated footings and 20 m soil column/strata below it. I need to consider Rayleigh Damping in this case. As per Rayleigh Damping, we have to provide two frequencies w1 and w2. Where w2= n w1, n=wi/w1 (n= closest odd integer greater than wi/w1). Here wi is dominant frequency of input earthquake motion, w1 is the fundamental frequency of soil-structure system. In my case wi = 10.17 rad/sec, w1 = 13.18 rad/sec, then n= 0.77. The nearest odd integer greater than n is 1. which we can't consider while solving Rayleigh Damping as w2 should be greater than w1.  

    Amaechi J. Anyaegbunam · University of Nigeria

    Hello Divyesh Rohit

     The natural frequencies used to construct the Rayleigh damping matrix for the structural frame is obtained from the solution of the normal frame eigenvalue problem

          |Kg - M*wi2| = 0   where | | stands for determinant, Kg = global stiffness matrix for the frame, M = the frame mass matrix. 

       Thus w1 and w2, that are used to construct the damping matrix, are natural frequencies of the frame and are in no way related to the dominant frequency of the earthquake excitation. In addition, a 3-storey frame will have at least 3 degrees of freedom when a lumped mass approach is used. In that case, the damping matrix needs to be at least 3 by 3 instead of 2 by 2 so that w3 needs to be considered also.   

  • C.V.C.Shekhar Reddy added an answer in Endosomes:
    How can I study the endosomal function of a protein?

    I am interesting in f.e. there is find that some new protein exist in endosomes, how would be good to study its function in endosomes? like isolate endosomal fraction from cells or?

    C.V.C.Shekhar Reddy · University of Barcelona

    It is interesting if you work on endosomes. Reveal of novel proteins that are in this pathway would certainly have big impact on Health Sciences. 

    Wish you all the best.

  • Nicola Minotti added an answer in Dental Restoration Repair:
    What are the current recommendations for protecting pulp before placement of any definitive restoration?

    Traditionally. after cavity preparation liners and bases are applied on the floor and axial wall of the cavity under all definitive direct restorations,This is done to protect the pulp from thermal, chemical and mechanical insults, It will be great if someone gives details of current understanding of pulp protection when the cavity is deep or when it is shallow. 

    Nicola Minotti · Private Dental Office

    I agree completely with James Field  : "....Atraumatic and progressive caries removal is the over arching approach, rather than removing caries to 'almost' the pulp..."

    The best procedures are those driven to let the tooth help himself .... pulpcells belongs to the   high sophisticate tissues   and display extreme living potential. 

  • Pierre-Adrien Bolze asked a question in Alexa Fluor:
    How to get rid of non-specific signals in the staining of PBMC in immunofluorescent microscopy?

    My PBMC are spread on slides with cytospin, fixed with paraformaldehyde 3.7% and cold methanol, and then permeabilized with Triton 0.5% at RT (15min) followed by 3 washes in PBS1X. I tried different blocking steps (BSA 3% or 5%, FBS 2%, goat serum 6%) for 1hour at RT or overnight at +4C. I am using a mouse IgG anti-human primary antibody diluted in BSA, followed by 3 washes in PBS1X. The secondary antibody is F(ab')2 goat anti-mouse IgG (H+L), adsorded on human serum, conjugated to alexa Fluor 488, also diluted in BSA.

    I have  a relatively strong peri-nuclear staining of 10% of the cells while these are supposed to be negative controls. (same with secondary antibody alone)

    Can this still be due to unspecific Fc receptor binding ?