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
  • Which is the best CAM system that provide 5 axis programming?

    Hi,

    5-axis programming of CNC machine is one of the most interesting topics for research in the relevant field. However, it is not obvious which CAM software provide better options to develop 5-axis CNC programs. 

    Enrique Gil Illescas · Universidad de Valladolid

    For me Master CAM is possible.

  • What is the most efficient method for Ranking the universities?

    Global University Ranking is of interest for all stakeholders nowadays, so we need the best fair method.  The methodology should be based on accurate and precise comparable performance indicators.  what is your openion about this issue and what are the best performance indicators? 

    Maris Martinsons · City University of Hong Kong

    The most efficient method may not necessarily be the best or the most influential. The most influential annual rankings are currently produced by the Times Higher Education magazine, Quacquarelli Symonds, and Shanghai Jiao Tong University. The first 2 were partners until 2009. All 3 of these rankings heavily weigh the impact of research publications. Performance on this KPI is typically measured by the total number of citations or the number of citations per publication.

  • Marc Tessera added an answer in Cognitive Systems:
    Is Chalmers' so-called "hard problem" in consciousness real?

    In his 2014 book "Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts" Stanislas Dehaene wrote "Chalmers, a philosopher of the University of Arizona, is famous for introducing a distinction between the easy and the hard problems. The easy problem of consciousness, he argues, consists in explaining the many functions of the brain: how do we recognize a face, a word, or a landscape? How do we extract information form the senses and use it to guide our behavior? How do we generate sentences to describe what we feel?

    “Although all these questions are associated with consciousness,” Chalmers argues, “they all concern the objective mechanisms of the cognitive system, and consequently, we have every reason to expect that continued work in cognitive psychology and neuroscience will answer them. By contrast the hard problem is the “question of how physical processes in the brain give rise to subjective experience … the way things feel for the subject. When we see for example, we experience visual sensations, such as that of vivid blue. Or think of the ineffable sound of a distant oboe, the agony of an intense pain, the sparkle of happiness or the meditative quality of a moment lost in thought … It is these phenomena that poses the real mystery of the mind”."

    Stanislas Dehaene's opinion is "that Chalmers swapped the labels: it is the “easy” problem that is hard, while the “hard” problem just seems hard because it engages ill-defined intuitions. Once our intuition is educated by cognitive neuroscience and computer simulations, Chalmers’ “hard problem” will evaporate".

    Personally, I agree with Stanislas Dehaene's opinion.

    Bernd,

    "I have forgotten that funny Rumsfeld statement, can you repeat it?"

    "There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know".

  • How do I eliminate nonspecific bands in final product?

    I have PRRL-ABCB7, a plasmid (8000 bp) with insert ABCB7 (3000 bp) subculture in top10 cells and purified by Qiagen midi. My work is to cut the insert from plasmid by double digesting it with Age and Mlu I (both from NEB). So Iam digesting 10µg of vector, first with Age in buffer 1.1 and run aliquot in the gel to check complete digestion with AgeI. Then iam purifying the Age digested vector by Ampure magnetic beads and digesting it with Mlu I in buffer 3.1. Running the gel after complete digestion with Mlu. From the gel two separate and clear bands were seen at 8000 bp (plasmid) and 3000 bp (insert), i have cut the band at 8000bp and purified  from gel. But after purification, when I check the final product in gel, along with 8000 bp band I have seen some bands at 7000, 6000 bp. When I am purifying the band from 8000 bp, why I am getting these non specific bands along with my desired product. I have tried so many times with different enzyme concentrations, incubation times, gel extraction kits and running slowly for long time in the gel (low gelling agarose), but nothing works and at the end the product is same. I have attached the pictures. Give me suggestions to eliminate these extra bands ??

    Thank you all in advance.                 

    Edward Boumil · University of Massachusetts Lowell

    I thought it did go all the way down the gel.  I don't know, it's not like she provide nice .tifs, contrast enhanced and the like.  Pretty blurry photos.

    But take a look at the left hand side of lane 2 (big lane), down near the bottom you can see the edge of the smear.  In my experience the give-away here is the lack of this smearing above the top band.   Assuming this is smearing, as I said its rather hard to see but what it looks like to me.

  • Can we use Yeast nitrogen base without amino acids as a minimal media for E.coli?

    Is there anything in the media that can act as carbon source for E.coli. myo-inositol is one but its concentration is very less.

    Florian Goetz · University of Greifswald

    You could add pure glucose to the Yeast nitrogen base w/o AS to add a carbon source and it would be still a minimal media.

  • Darren Bradshaw added an answer in Polytopes:
    When analysing the topology of a MOF built from polytopic ligands do you think it appropriate to represent this ligand by two or more nodes?

    For example: a 4-c ligand could be represented by two 3-c nodes if this describes the structure better.

    Darren Bradshaw · University of Southampton

    This would be more like the image below than the cross I think, an example of a decorated 4-connected node, essentially replacing a node of N-connectivity (4 in this case) by N-vertices (i.e. the rectangle), a strategy typically employed to increase pore size in network structures (see Yaghi/O'Keeffe). You could describe both in this way since the Ag ion is acting as a link between the 3-connected nodes/ligands if you take this unit as a whole - similar to an SBU if you like. Not sure what the rest of the network looks like connected through the dicarboxylates, but as long as it is clear how you've defined network connectivity then I do not see a problem either way. As an example, HKUST-1 can be described as a 3,4-connected twisted boracite net taking the paddlewheels and BTC linkers as the nodes, but it could equally be described as pcu (as in the original Science paper I think) if one takes a larger unit as the node. Either is valid.

  • Jingjing Shen asked a question in RAW 264.7:
    Could anyone recommend a short peptide sequence that has shown immunogenecity and to be potential vaccine?

    Could anyone recommend a short peptide sequence that has shown immunogenecity and to be potential vaccine, such as Papillomavirus (HPV) E7 protein? It would be better, if there is some mouse macrophage (RAW 264.7) cells activation data about this peptide. Thanks a lot!

  • What metrics could be used to measure the behavioral changes and adoption rate in doctors due to initiatives by a pharma company?

    If a company has launched a drug recently and needs to check effectiveness of the various initiatives, in terms of the change in behavior towards the new therapy among doctors.

    Helene Moore · Ryerson University

    Hi. You can get data on total prescriptions that would include renewal (Trx) or new prescriptions (Nrx) for a particular drug. You can have that data on the national or regional level, also at the physician level. You can also get sales in Revenues but prescriptions is probably a better proxy if you wish to link this to behavior.

  • Mohammad Reza Norouzi asked a question in Motor:
    How is method Manufacturing a reluctance motor?

    How is method Manufacturing a reluctance motor?

  • What are the possible sources of Halite (NaCl) salt in an Archaeological site located at 150 Km from sea?

    Historical stones contaminated by Halite ! looking for possible origins

    Aalil Issam · Université d'Orléans

    Thank you for your answers. The site studied is the Volubilis Archaeological site in Morocco.

  • Can it be avoided that in ethics naturalisic fallacy indicates a defect of reasoning blamed by naturalists to derive prescriptions from descriptions ?

    Naturalistic fallacy is an expression found for the first time in Principia Ethica, a work published in 1903 by the English philosopher George Edward Moore. According to it, the concept of good which is at the basis of moral discourse is a simple concept and can not be further defined.

    When you claim to identify it with some natural property, such as useful or pleasant, it falls into the naturalistic fallacy, which includes both the naturalistic ethical theories and the ethical metaphysical theories. The choice of a solution can not entirely exclude the other ones.

    It is possible to escape this contradiction by adopting the intuitionistic solution by Moore for which the good is sensed as the yellow color: in this way, you will know what it is and there are no alternative solutions. Moore soon realized that his solution, by virtue of intuitionism, could lead to subjectivist drifts: he pleaded this risk by focusing on the fact that the good is absolute, it expresses an intrinsic and universal value.

    In this way, any possible subjectivism is reset at the start. However, a new problem showed up: given that the good is universal, absolute and independent, which is its nature? Certainly, it cannot have an empirical nature, because if it did it would fall into the naturalistic fallacy; but neither can it be metaphysical, because otherwise you would re-awaken the metaphysical fallacy. The solution is then advanced  by Moore in recognizing that ‘good’ has an ontological status equal to that of Platonic ideas and numbers, which are absolute and objective without being either empirical or metaphysical: in this sense, the ‘good’ is just as number four.

    In later writings, Moore would soften his position, by arguing that the good depends on the intrinsic nature of things; in this way, he will approach Aristotelianism from Platonism... ".

    In the explanation of the onset of the 'naturalistic fallacy', one moves from 'having to be' which is the term used by Kant to indicate what is required by the moral law, regardless of any condition of fact and the entire order of nature. The moral law is an expression of reason in its practical use, that is, determining the will. The duty to provide what the law says to man, be reasonable but finite, exposed then to the empirical influences of  subjective motives and subjective inclinations, is expressed in the imperative form.

    Therefore, the ‘need to be' indicates "the relationship between the objective laws of the will in general and the subjective imperfection of the will."

    Then, since the moral imperative is not subject to any end, nor is placed by the faculty of desire, it addresses people in categorical terms, that is unconditioned, and then it is intended: "because you have to."

    It is by virtue of this duty that the possibility of action properly human is deducted: not the physical possibility to act, which belongs - as Kant says – to the order of causes and effects, but it is the moral possibility to fullfil the moral law or not, that qualifies man as a moral entity. Between the world of being - that is, of what is the way it is, according to the laws of nature - and the world of 'having to be'- that is of what is required by the moral law - an absolute hiatus opens up, the same as Hume had pointed out, denouncing the naturalistic fallacy which is to take prescriptive propositions, that is related to having to be, from descriptive propositions, related to what it is .

    David Wise Thomson · Quantum AetherDynamics Institute

    Those are profound insights, which appear self-evident to me. 

    No cultural system can be perfect, but I agree that a system instilling a deep appreciation for morality and its effect on life would be far more beneficial than an endless list of laws, rules, and regulations. 

  • Abbas Raza asked a question in Orchiectomy:
    EAE disease and effect of surgical castration?

    Hi there

    Has anyone looked at the effect of surgical castration (orchiectomy) in male C57BL/6 and how it affects the development of EAE (experimental autoimmune encephalomyelitis)? I've not found very clear data in literature about any exacerbation so if any researcher here has seen this effect in B6 do let me know.

    thanks

  • Souad Neffar added an answer in Colorado:
    Can anyone send me thes papers?

     Please , i need these papers  to make comparisons with the results of another research.

    Ranelli, L.B, W. Hendricks, J.S. Lynn, S.N. Kivlin and J.A. Rudgers. Biotic and abiotic predictors of fungal symbiont distributions in grasses of the Colorado Rockies. Diversity and Distributions

    Xiang D, Verbruggen E, Hu Y, Veresoglou SD, Rillig MC, Zhou W, Xu T, Li H, Hao Z, Chen Y, Chen BD. 2014. Land use influences arbuscular mycorrhizal fungal communities in the farming-pastoral ecotone of northern China. New Phytologist 204: 968-978

    Thank you.

    Souad Neffar · Université de Tébessa

    Hi,

    Thank you very much.

    Souad.

  • What are the main causes of retention time instability in reversed-phase analysis by HPLC?

    In analysis of a weak acid with pKa of 4.6, using mobile phase of phosphate buffer pH 7.7 and methanol (63:37, v/v) and hypersil C18 column, the retention time of this analyte is not stable (it is decreasing with time), although different types and composition of buffer and different pH were tested, but the problem was the instability of the retention time (decrease in retention time).

    Tyler Trent · Teledyne Tekmar

    The organic concentration of the mobile phases might be off which could lead to rt shift. The pH of the mobile phase could have changed from batch to batch. I have had the pH be off and that caused me a rt shift.

  • What would you do with oligometastatic adrenal lesion six months after sigmoid colectomy for cancer, treatment curative or palliative?

    Sigmoid colectomy in an 84 year gentleman stage 3 . Adjuvant chemotherapy six months. Pet scan. On follow up showed adrenal lesion 4 .5 cm size .met. Would you operate or advice palliate chemotherapy

    Wolfgang Hohenforst-Schmidt · Klinikum Fürth aff. University of Erlangen

    Definitely true, I agree to Pn Haray

  • Theo K. Dijkstra added an answer in EFA:
    What mean "maximum iteration exceeded" and "Heywood case" in EFA with bootstrapping on R?

    Hello, for my thesis I do an EFA on a questionnaire (items = 42, N=420) with bootstrap (n.iter= 1000).

    For the 4 factor model R indicate "maximum iteration exceeded" and "Heywoodcase" what this mean? and is it a hudge problem? Because for the 3 factor model there isn't such message but the 3 factor model is less interesting.

    Thank you for your help and advices !

  • Ulrich Mutze added an answer in Asteroids:
    There is a dark ring on an asteroid, is it noise in the picture? or not?

    Hello, As you can see in the picture, there is a dark ring on an asteroid, is it noise in the picture? or something else? totally it is like a ring not a burned pixel. 

    Roberto, my dust grains never behave that way. Can you provide any evidence?

  • Godfried Van Moorsel added an answer in Parasites:
    What are the associations between (invasive) exotic host species and native symbionts (e.g. parasites)?

    I am looking for publications on (preferably marine) invasive, non-indigenous species that act as host for native associated species. Native predators / grazers on exotic prey / plants is also fine. I am grateful for your suggestions.

    By Thieltges et al: on the dilution of mussels parasites by the presence of the invaders Crassostrea and Crepidula.

  • Robert E. Erard added an answer in Subjectivity:
    Do you use a diagnostic cutoff value of “a”?

    An imaginary researcher obtained a diagnostic cutoff value of “a” with sensitivity of 90% and specificity of 90% for diagnosis of rare illness. Data of 20 in 200 subjects exceeded “a”; however, all 20 subjects were diagnosed normal after close examination. Is it reasonable not to obtain any patients from 20 subjects? I expected 18 of 20 patients (90%) were diagnosed abnormal. Is it a bad expectation? Do you use the cutoff value of “a”?

    Robert E. Erard · Psychological Institutes of Michigan, P.C.

    Since it is a rare illness, the key question is whether the subjects were drawn from a population sample with a high base rate of the illness or whether the population sample was more representative of the general population. If the base rate of the subject pool is 50% (i.e., if 50% of the subjects are expected to have the condition), then it is indeed unlikely that none would be identified by the gold standard as having the condition. (You can determine just how unlikely by using the binomial theorem for a probability of 90%). If, however, the base rate in the subject pool is much lower than 50%, it is quite likely that you will not find very many (or quite possibly any) true positives. You can use Bayes' theorem to determine the probability of a true positive (i.e., the Positive Predictive Power of the test) for a given base rate as follows:

    PPP = BR x Sensitivity/(BR X Sensitivity) + (1 - BR) x (1 - Specificity)

    In your hypothetical, you know that Sensitivity and Specificity both equal 90%, so you just need to plug in that and the base rate (BR) to get the Positive Predictive Power.

  • What are the reasons why the standard duration of stress corrosion tests (described in the NACE TM0177) is set in 720 hours rather that another value?

    The Nace TM0177 sets the standard duration of these tests in 720 hours and it does not give any explanations or bibliographic references about the reasons for this rule. On the other hand some authors use a test duration of 730 hours for the same kinds of test which are described in the normative reference ( the Nace TM0177).

    I would like to know what are the reasons on which is based the indication of the tests duration and/or when a different choice can be made.

    Thanks in advance for your help!!

    Rana Afif Majed Anaee · University of Technology, Iraq

    I think that it is necessary to ingress the corrosive species onto materials to complete the mechanism of SCC which is consist of many steps:

    1. Initiation
    2. Crack growth stage I, with crack growth direction about 45o relative to the tensile stress direction. 3. Crack growth stage II. 4. Fast fracture.

  • Ali Taghavi added an answer in Geometry:
    Can someone help me on this question about the Geometry of CP^{2n+1}?

    We consider CP^{2n+1} with its natural Riemannian metric(The quotient of S^{4n+3} under the natural action of S^{1}. We denote by "d" the metric which is induced by this Riemannan metric.

     We define F  on  CP^{2n+1} with F(x)=the (unique) farthest point to x(with respect to the above metric d).

    Is F(x) well defined?(Is the point F(x) unique?). Is F \ circ  F=Id  (that is F^{2}=Id?).

    Now for every x, we consider M(x)=All points  y \in CP^{2n+1} such that d(y,x)=d(y,F(x)).

    Is M(x) a ( codimenion one )totally geodesic submanifold of  CP^{2n+1}? Does  M(x) separate CP^{2n+1} into two disjoint part with the same area?

    How many geodesics join x tp F(x)? Is it true to say that any geodesic which joints x to F(x) must be perpendicular to M(x)?

    All of the above questions are motivated by n=0(the sphere).In this case the answer to all of the above questions are affirmative.

    Note that we exclude CP^{even} since it has the fixed point property, so obviously the above F does not exist.

    Ali Taghavi · Damghan University

    Dear  Daniel  Guan;  The fibre bundle is $$ \{(x,y) \in CPn\times CPn \mid d(y,x)  is maximal\}$$

    right? 

    So it is isomorphic to projectivization of the orthogonal bundle to the canonical line bundle over CPn

    So I can not underestand why you say this bundle is always trivial.  Am I missing  some thing?

  • Shahnawaz Ahmad Wani added an answer in Organ Bath:
    What are recent techniques to understand mechanism of smooth muscle contraction?

    I am using an organ bath instrument to understand smooth muscle contraction by metal pollutants, are there any new techniques to understand the same mechanism?

    Shahnawaz Ahmad Wani · Jamia Millia Islamia

    oh great..

  • Alejandra Pando asked a question in Aggregation:
    Does anyone know the mechanism behind this result?

    this is a reaction with citrate modified gold nanoparticles,thiolated probes and genomic DNA. First, i'm not sure for what reason you use thiolated probes, and second which is the mechanism behind the result you observed? 

    I know that ssDNA stabilized the gold nanoparticles, so that they don't aggregate, and dsDNA can't do this, so the gold nanoparticles aggregate.

    Thanks! 

  • How can I determine the cut-off frequency in a microstrip designed to measure permittivity using Nicholson-Ross method?

    Nicholson method takes  S-parameters(S11 and S21) and cutoff frequency/wavelength as input .

    If suppose operating frequency is 10GHz, what is the cut-off frequency?

    Mohsen Bakhoda · Yazd University

    cutoff frequency define for waveguide , not microstrip .Because in microstrip the TEM mod Excite and TEM mode don't have any cutoff frequency

  • Matthew Mcgrath added an answer in Amino Acids:
    Would anyone like to collaborate in the synthesis of the amino acids shown below?

    Dear All

    I am looking for cooperation in synthesis of some amino acid derivatives that structures are attached to this question. Please write me if anyone will be interesting. Thank you 

    Matthew Mcgrath · Write Train Create Pty. Ltd.

    I think these are interesting compounds. Do you have lab space and resources for someone to make them in Gdansk? I would probably use a dimethylsulfone, an amino aldehyde and a base as starting materials for the first sulfone. 

  • Huasen Wu asked a question in Writing:
    How to justify our own work when we obtain stronger results under simplified assumptions?

    Hi everyone,

    I am writing a paper where we obtain stronger results under much more simplified assumption. How can I justify the contribution of our work?

    Currently, I am using the following flow (in the introduction):

    In this paper, we study ... problem ...

    The above problem can be viewed as a special case of [Ref], where they consider more general settings ... . but the algorithm in [Ref] is computationally ineffecient. /*I don't feel comfortable about this paragraph; it may be move to some other places. For example, after discussing our contributions? */

    To tackle this problem, we consider simplified versions of the problem ...

    With these simplified assumptions, we are able to obtain computationally efficient algorithms, ... and achieve (better performance)

    Even with these simplified assumptions, the problem is still challenging. ... /* challenges of the simplified problem */

    To address these challenges, ... /* our contribution */

    Could you give me some suggestions, or references that you think can be a good model?

    Thank you very much!

  • Why the current falls after the cathodic and anodic peak in Cyclic Voltammetry?

    While achieving the oxidation or reduction in Cyclic voltammetry one gets peak current. But if we further increase the voltage then there is a fall in current.
    My questions are:
    1. We know any peak appears due to the tussle between two opposing forces. What are they in case of Cyclic Voltammetry?
    2. What is the reason of fall in current after reaching peak current?
    3. Which peak is oxidative and which is reductive?( I found from literature many use the anodic peak as oxidative and many as reductive)

    John D. Watkins · National Energy Technology Laboratory

    If you are talking simply about a dissolved redox couple in solution then the peak is a direct result of diffusion. Assuiming this redox probe is fully reversible (a fast electron transfer probe not limited by electron transfer kinetics) then the peak is roughly defined by the Nernst equation once the reversible potential is achieved. The peak occurs when the diffusion gradient can no longer supply redox material at a rate to satisfy the equation and thus the current is seen to decrease. The diffusion gradient will decrease as the diffusion layer thickness increases with time. Thus the current will decrease to a diffusion limited region from the peak. If you supply an additional mixing force other than diffusion then often you will not see peaks, for example in rotating disc or even just with heating.

    Which peak is which is merely a naming convention. Mostly the anodic peak is defined as having +ive current at +ive potentials, however different groups can have different naming conventions.

    I suggest you read "Electrode Dynamics" by Adrian Fisher which is an excellent basic guide to concepts and really wasy to read.

    Then "Electrochemical Methods" by Bard and Faulkner for more depth as well as "Understanding Voltammetry" by Richard Compton for more details and examples.

  • Methods of achieving high titre stocks of Dengue virus 1, 3 and 4 from tissue culture?
    I am looking for any insight/papers into this specific topic. I have listed some additional information below.

    1. The cell lines used may be of any type, but would prefer mammalian cell lines. (It is possible that one may not get high titre stocks from mammalian culture. In this case, insect cells are ok).
    Emerson De Castro Barbosa · Centro de Pesquisas René Rachou - Fundação Oswaldo Cruz, Belo Horizonte, Brazil

    In our laboratory, we have been using only C6/36 cells for dengue type 2. We get viral titer of 10^7 at 5 days dpi following infection with an MOI of 0.1 too.

  • Dear All, Does anybody know how to measure the electrical resistivity of unsaturated concrete specimens which contain chlorides?

    I have concrete specimens have a percentage of internal chlorides (added to mixing water) and I need a way about how to measure the electrical resistivity for the unsaturated specimens.

    Hayder Oleiwi · University of Salford

    Dear Imrose Bin Muhit, Thank you very much for your answer. Actually I have already known about the attached article, but I am looking for a way to measure the resistivity for unsaturated concrete that contains chlorides, for example 2% of cement weight mixed with mixing water of concrete specimens.

  • GC-MS analysis of natural products, How it's possible to have two different retention time in the GC-MS spectra of the same compound?

    For example I have at 19.10 min carvone and 21.86 min also for carvone????? I find some articles with these kind of ......

    If at 15.8 min I have a compound followed by the same compound 16.5 min in the same spectra, this mean that the compound was to concentrated, or the separation failed? 

    Look at Fig. 4 and the corresponding sample table.

    John Peter Bartley · Queensland University of Technology

    These are undoubtedly different compounds which happen to have similar mass spectra so that the library search algorithm ( which is really quite crude) cannot distinguish between them. You should not use library search as your only criterion for identification.  As other people have said, you need a pure standard.  You could also determine the Relative Retention Index and compare this to the literature value for your column.