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

  • J. Kazimiroff added an answer in Saliva:
    Are saliva tests valid/accurate/good enough for research within the field of epigenetics/DNA research?

    Setting up a project abroad and would really like to use saliva instead of blood. Any good references concerning this topic?

    J. Kazimiroff

    We used a protocol for saliva with an RNAase to stop the enzymatic breakdown when collecting saliva.protease inhibitor cocktail (Calbiochem; 1:100 dilution) within ten minutes of collection, prior to freezing at -80°C.but we were looking at interleukins. 

  • Alexander Pugachev added an answer in Circuit Design:
    What's the problem with the model attached below?

    Hi everyone..
    Anyone please help me with the model (figure attached below), why i can't connect the sequence analyzer(phasor) there at that point.? 

    Alexander Pugachev

    Hello, Mansoor!

    You have to put converter from SymPowerSystems' units to Simulink's ones. For example, in this case it could be done by Voltage measurement. See the attached. Regards

  • Ig Madrazo added an answer in Parkinson's Disease:
    What are the etiologic factors for Parkinson's disease and are there any preventive measures?

    I have observed 3 persons who had Parkinson's problem. One thing was common among them. All of them were versatile personalities i.e. multi-talented persons in their past life. Is there any correlation? If anybody can explain. 

    Ig Madrazo

    My work is related to treat PD surgically,  any Q relayed yo this topic?

  • V.G. Irisov added an answer in Conductivity:
    Any advice on conductivity tensor and lattice symmetry?

    In book it says" If a field in x direction induce any current in y direction,by exploiting the symmetry,one can predict  a same current will arise in -y direction,only consistent possibility is zero current so the conductivity tensor is diagonal  in cubic symmetry lattice"

    What hell he is talking? why field in x direction can induce current in y direction?And if so,why will be same current induced in -y direction? why those stuff related to symmetry? I have no clue about this

    V.G. Irisov

    It's an ugly explanation of the symmetry principle: a field in x-direction CANNOT induce any current in y-direction (or z-) because otherwise a mirror symmetry of the lattice would be broken. As a result in a cubic lattice, a filed in x-direction produce ONLY x-directed current, y-field -- y-current, and z-field -- z-current, i.e., the conductivity tensor is diagonal.

  • Franklin Ohikhena added an answer in Analytical Chemistry:
    Dear friends, How can I prepare Iron 1000 ppm standard solution? I found many methods for that and I am not trust any. plz, who is experience in Iron Analysis and determination by spectro photometer?, I need both of standard preparation and spectrophotometer determination, regards to all
    Standard solution
    Franklin Ohikhena

    how do i prepare a standard Iron III Chloride solution which contains 0.00195g/mL Fe?

  • Clifford Chafin added an answer in Foundations of Quantum Mechanics:
    How do we understand a conservation law (Noether's theorem) in quantum mechanics?

    In the classical mechanics Noether's theorem says that

    "if a system has a continuous symmetry property, then there are corresponding quantities whose values are conserved in time"

    As a simple particular case, a quantity A that doesn't depend on time explicitly, neither through other parameters on which it depends, i.e. dA/dt = 0, is a constant of motion.

    The question is what becomes of this law in quantum mechanics (QM)? Does it hold at all? And if it does, what is its meaning?

    The QM gives the following formula for the time derivative of an operator Ȃ:

    (1) dȂ/dt = ∂Ȃ/∂t + i/ħ (ĤȂ - ȂĤ),

    where Ĥ is the Hamiltonian of the system, and Ȃ is a Hermitic operator attached to an observable of the system.

    Assume now that Ȃ doesn't depend explicitly on time and commutes with Ĥ, therefore dȂ/dt = 0. How shall we understand this result? Does it mean that the value of the operator Ȃ is fixed during the system evolution, even if we don't measure it?

    Or, alternatively, does it mean that performing a measurement of Ȃ on identically prepared systems, we are bound to find the same value of Ȃ?

    In other words, in the QM, a quantity which is a constant of motion, possesses a value, and it is fixed in time, independently on whether we measure it or not? Or, alternatively, it takes a value only if we measure it, and the value is the same if we repeat the measurement on identically prepared systems?

    Clifford Chafin

    It is at least interesting to look at this from the standpoint of classical field theory for one particle systems.  Here the conservation laws that arise from the usual spatial symmetries appear as the global averages <E>, <p>, etc. which correspond to the sum over a large set of quantum measurements.  When taking such a measurement it is arguable that these are not conserved for such single events.  

    For the many body case I don't know if anyone has such an analog.  I developed a many time label version where one can get an analogous result for the "equal times" slice of the system.  

  • AHMED ALBARRAM added an answer in Static:
    How can I deal more effectively with a Time Period in the Static General step?

    Hi all,

    Please, would someone help me with that step. Actually, when I submit my model to be analyzed, the time of analysis is very short (less than a minute).

    So, I would like to make it much longer in order to give me a reasonable results. Any advice to deal with that?

    Note: I attached two pictures for that step.

    Kind regards,

    + 1 more attachment


    Hi Bala,

    Thanks for your answer. Regarding the max. increment size, how much do you think I can increase the value? For example, can I make it 10?

  • James Garry added an answer in LabVIEW:
    How do I pulse a Digital Output in Labview?


    i am new to Labview and the Dataflow programming.

    I am using Beckhoff Hardware Bk9100 with Modbus TCP and Labview 2014. I have a heater (DO) and want that the user can type in an Value in % (in the example 5 sec are 100% power) so for example at 50% i need the DO for 2.5s on and 2.5s off. I dont need real time control and the controlsystem is sluggish.

    But how can i realise this with Labview? 

    I tried to make a Do while and for the time i used a waiting time for each loop with 100ms so if i need 2.5s on(true) their counter goes to 25 iterations.

    Maybe this is the right direction but i dont know how can i finish this. So i hope someone can show  me the right direction.

    Thanks a lot

    James Garry


    A Do loop is one way to realize this.

    Have a 'wait'  inside it so that it runs at 1Hz (for example).

    Use a shift register to increment an interger, and reset it to 0 every time it gets to (say), more than 10.

    Then test if it is greater than the user-provided value (0 to 10), and set a local variable to be true. So if the user provides '5', you'll have a duty cycle of 50:50 (with an 'on' for 5sec, and off for 5sec).

  • Ahmed Abdel-Latif Mohamed asked a question in Neutrons:
    How can I verify that the mass attenuation and neutron removal cross section correlate with spesfic element in certain compositions?

     I have calculated both them and made a plot with the contents of this element 

  • Ahmed Abdel-Latif Mohamed asked a question in Neutrons:
    How can I verify that the mass attenuation and neutron removal cross section correlate with spesfic element in certain compositions?

     I have calculated both them and made a plot with the contents of this element 

  • Andrea Piroddi added an answer in Wireshark:
    What are the best opensource tools for packet capturing in network research. The aim is minimize packet losses experienced in wireshark(50%)?

    Different solutions have been employed but packet loss ratio is very high. The best up till now has been wire-shark. Kindly guide as to how we can increase the capture ratio and what software are commonly used in the community for this purpose.

    Thanks in advance for your help.

    Andrea Piroddi

    you can find interesting OpenNMS (http://www.opennms.org/) and Capsa Free (http://www.colasoft.com/capsa-free/). Another one is a web based network tool Xymon  that you can find at http://sourceforge.net/projects/xymon/. In my opinion OpenNMS is what you're searching for.

  • L. Slewa added an answer in Centrifugation:
    How do I prevent clusters during the spray deposition of ultra-long Silver Nanowires?


    I grew Silver Nanowires and followed the growth protocol of this recently published paper:

    Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells (DOI: 10.1088/0957-4484/26/26/265201)

    The as-grown and drop-coated Silver Nanowire films looked fine (please see the attached picture).

    However, during spray deposition, clusters of Silver Nanowires seem to clock the nozzle aperture (see second picture please).

    The washing protocol was:

    Dilution in Acetone with a ratio of 1:2, centrifugation at 2000rpm

    Dilution in Acetone, centrifugation at 2000rpm

    Dilution in Water with a ratio of 1:2, centrifugation at 6000rpm

    Dilution in Ethanol with a ratio of 1:2, centrifugation at 6000rpm

    Storage in IPA for the later spray deposition.

    During each step, the solutions were treated in an ultrasonic bath for 30 seconds, at the end for 2min until no agglomerates were visible. Do you have an idea how to improve this process to prevent agglomerates and maybe also the sonication treatment?

    Thanks a lot,


    + 1 more attachment

    L. Slewa

    Dear Marco  the acid will not decrease the Molarity only helpe you to obtain an aqueous solution 

    read my thesis page 25

  • Hamdan Zaki Hamdan added an answer in Genotyping:
    Are there any way to determine the exact cause of genotyping deviation from Hardy Weinberg equilibrium (HWE)?

    It is well known that, there are many causes of deviation of the genotyping from the HWE. However, i wounder are there any way to know excatly the cause of this deviation from HWE.

    Hamdan Zaki Hamdan

    Thank you very much Asia, Vladimir,Josef, Vaslu,  Angela, Sean for your contribution and enriching the debate. Your answer was helpful.  

  • Sushma Dagar asked a question in Fiji:
    Does anyone have experience with analysis of Structured illumination microscopic images?


    I am trying to find a suitable thresholding method for the SIM images. I have done ICC on mouse cortical neurons and then have taken few image using Zeiss Elyra PS-1 microscope. I am doing analysis in Image J (Fiji) and have tried the automated methods available there. But they did not seem to work.

    Thanks in advance


  • Douglas D. Gransberg added an answer in Sponsorship:
    Is there a relationship between the sponsorship of research projects and the quality of their results?

    I was involved in a discussion on an academic mailing list where the question popped up, whether research sponsored by corporate foundations produces systematically different (higher or lower quality, biased etc.) results than research sponsored, for instance, by public research councils or science foundations. This seems like a specific aspect of the wider question on how sponsorship  relates to research quality. Any suggestions?

    Douglas D. Gransberg

    I think that the difference may lie in whether the sponsor is supporting basic or applied research. Applied research by definition should be immediately usable and hence there is a real life check on its quality.

  • Virendra Kumar Saxena added an answer in Water Resources Management:
    How do I detect underground water location point and quantity availability for agriculture purpose ?

    The agriculture is the main cultivation of my village .The cost of the borewell is around 1 lakh rupess, and formers are getting loans for it.  It is very difficult to predict location of water available in the agriculture land; many times it leads to failure even after several attempts. Because of mansoon and borewell failure, formers having 10 acres of land working as a daily labour for 100 rs per day.  Many formers are migrating to towns, city for labour jobs and this is the worst condition for them. So kindly suggest me the feasible advance technique for the benefit of farmers..

    Virendra Kumar Saxena

    For giving location point for drilling sites, there are  large number of methods are available and well known. This particular problem is concerned with former who are not economically sound, hence care should be taken to recommend site for drilling. Hydrological investigations and than  Electrical Resistivity by direct corrent method may be a option. Pump test will provide the efficiency of drill/ bore well.

  • Ronald Waterbury added an answer in Catholicism:
    Is there any literature that deal with specifically or in passing of conflict between Catholic priests and indigenous communities?

    I'm working on a paper about an incident in which a Catholic priest was stoned by indigenous villagers in Mexico because he attempted to "modernize" their practices; i.e., in essence convert them from "folk catholicism" to orthodox Catholicism.

    Ronald Waterbury

    Thanks to every body for the very helpful suggestions

  • Lawrence Ian Geller added an answer in Tourism:
    Is there a case study for festival tourism?

    Festival impacts are noted within the literature and so too are the impacts of tourism.  However, I am looking to see if there are any papers which specifically address the impacts of 'festival tourism'.  A case study approach, perhaps.  If you can guide me to any published (or unpublished) work, it would be appreciated.  I am actively searching for material, so if I find some resources whilst waiting for a response, I will add them to this post for others to view.

    Please note, I am looking for specific festival tourism impacts, not generic festival impacts or tourism impacts.

    Thank you in advance!

    Lawrence Ian Geller

    PricewaterhouseCoopers European Economic Outlook June 2004 - The economic impact of the Olympic Games - http://www.pages.drexel.edu/~rosenl/sports%20Folder/Economic%20Impact%20of%20Olympics%20PWC.pdf

    Eliza Grames & Mary Vitcenda (2012) - Community festivals—Big benefits, but risks, too - http://www.extension.umn.edu/community/news/community-festivals/

  • Louis Brassard added an answer in Democratization:
    Taking Occam out of traditional academic paths, is it necessary to disinguish between an agent and a passive intellect? Has it not only a moral value?

    We know that obsessed by prevailing stupidity, the main problem of Ockham was that he could not understand the lengthy explanations of the others on systems of life, with the consequence that he found himself having to take every day mountains of notes to be simplified. One day the spark snapped and caught fire the city of London. Occam came to two conclusions:

    a) The wood burns better if you pour on alcohol

    b) either someone simplified linear equations, or would not ever understand.them

    Taken from this last thought, he formulated the ‘teoria prima’, i.e. what today is called Occam's Razor. The latter, penetrates with pitiless safety in the forest of disorderly too many metaphysical schools and cuts inexorably entities and concepts redundant, in obedience to a policy of "economy" of all modern taste: much debated was then the dispute over the intellect between Thomists and Averroists. For some, it was personal, for the other impersonal. If personal, it had to be identified with the Word of God, or conceivable as a quid intermediate between the Divine Word and the real intellect of men?

    William of Occam does not allow to be taken by the question, and raises a simple question: "is it necessary to distinguish between an agent and a passive intellect? Doesn’t it have only a mental value?". In his reply he denies the value of this distinction comes the affirmation of the unity of the soul with its cognitive act.

    The same question is for the Aristotelians, who proclaimed it necessary the intervention of categories and universal principles in the cognitive act, "is it necessary ‘de facto’ or just words?".

    His answer reveals the empirical and nominalistic character of his philosophy: only source of knowledge is the sensible intuition, which presents individual objects and leads us to a judgment on their actual existence; all other forms of knowledge derived from it. Continuing in this rigorous empiricism, William of Occam denies any actual reality to universals: intuition captures only individuals and they do not possess any universal nature. In fact, if it existed in the individual, or it would be part of himself, and then it would not be universal but individual, or would not be part of the individual and then it would mean that these can exist without it. William of Occam concludes that the so-called universals are only "names" with which you label groups of special insights. But they remain outside of the objects and do not represent the essential nature.

    With this nominalism William of Occam was opposed both to the theory of abstraction of the Thomist school as to  "common nature" of Duns Scotus, but above all it  pointed out the uniqueness of the intellect because unique is the set of cognitive operations: memory and conceptual knowledge not departing from the empirical intuition. Then you must acknowledge that the “logical razor "Occam" cuts the arid branch of the agent intellect and continues his work even amputating the species as unnecessary intermediary between the object and the senses. Along the same lines William of Occam criticizes concepts of substance and cause: our knowledge of the objects runs out in the clarification of their quality; the substance would be only a negative entity, a non-quality and therefore useless to the effects of knowledge; experience also introduces us to the only differences between the various objects and the laws governing the succession of different phenomena, but inside them it can be seen no causal link and therefore this is a postulate without justification.

    It is in a certain sense relaxing way to reflect on the smart simplicity of Occam, taking advantage of what has been written - in the form certainly semi-serious by the ironic Professor Fabio Cardone. We quote literally his "Commentary on the physical theories – the Occam's razor".

    The first possible comment to the physical theories starting from the ‘democratic’ razor is that they are also based on the fact, subjective, of a democratic principle: what is plausible is more acceptable if the majority accepts it.

    The second comment is that physical theories are based on another subjective fact, the so-called aesthetic principle: what pleases the majority is accepted. In science, the union of the aesthetic and the democratic principles is humanly invincible and can be won, with patience, only by unambiguous experimental evidence, Galilei docet! A system of physics whose theories be the dialectic result of this union can not, and should not, be won with subjectively by pure human reasoning, but can be defeated objectively with experiments.

    The third comment is the following statement. To believe that nature is simple is beautiful and easy, leading to explanations of minimum effort of understanding and consequently with more opportunities to satisfy the principle of laziness and that of aesthetics. The majority likes what is easy and calls it the simplicity of nature complying with the principle of laziness and it achieves the union of the aesthetic and the democratic principle: the razor

    The razor cuts the possibility that nature be complicated, but it can not be excluded. Then we come to express the physical laws and the laws of nature by successive approximations, or by successive illusions of simplicity or better by subsequent razors: the physical theories. Knowledge apparently would be a succession of razor bumps, but sooner or later it's time to change razor. The choice of Lorentz, using a historical analogy on the theory of relativity, is the moment when you have to change razor, the former having the blade worn, unable to cut the new experimental evidence.

    In the construction of a physical theory a question arises, why did not you accept the possibility that nature can be deceptively simple or seemingly complicated, and so fair-minded consider the two possibilities without being subject to the "principle of laziness."

    The process of building a physical theory could start, instead of the razor, from the observation that the logic of nature is not human logic. The field of unchallenged domination of human logic is the language of representation of nature, by physical theories; such language can only be mathematical i.e. quantitative and synoptic in its ideogrammatic form. The task of human logic can not be to shave but adapt; always using the language, the logical characteristics of the entity measured by the logical characteristics of mathematics with which the theory describes.

    It can be concluded with an example that illustrates and at the same time give the recipe operating of such a sort of principle of " logic adhesion " between the logic of nature, the objective data of the measured phenomenon, and human logic, the subjective data of the language used. If the measured variables have a discrete structure or continue it must search for a correspondingly continuous or discrete mathematics. In addition it will require that the unknown variables of the mathematical language are only those corresponding to the variables measured.

    Louis Brassard

    Dear Gianrocco,

    Aristotle and even Lucretus recognized that the universe has determistic aspects and some undeterministic aspects.  It is not one or the other.  Conceptual expression which is epitomized in geometrical construction had originally absolutly no way to deal with the underministic part.  But the atomists had a notion of swirling in the atoms which would inject some creativity into the atom pattern formations.  Some atomists had a notion of natural selection could explain biological evolution.  Darwin developed this idea to the point where it became the mainstream biological thinking.  What is interesting in Darwin's approach is the combination of the undeterminist and the determinist.  Darwin's model is essentially a model of stabilisation of randomness under the constraint of interaction;  So it is a combination of these two notions.  It is interesting to note that this break through of the biological thinking happen precisely at the peak of the deterministic thinking in physics in the form of the Laplacian universe where absolutly nothing new that cannot be predicted can happen.  But Darwin ideas was fertilizing the physicist minds.  Marwell was speculating that free will could enter the universe through randomness at singular point where determinist fails. But the seed of the evolutionarry thinking were planted deep in the natural history movement of the 16th and 17th century.  All the naturalist philosophers knew that the earth and the solar system were formed through a gloud of atoms and that the earth was formed just a limited time in the past and thus that life had to have evolved from the inanimate matters.  Even Descartes knew that.  The real question was how that could be achieved and expressed into a scientific model.  Darwin model is a purely mechanistic model with window open for randomness to bring in novelty. There are precedent to Darwin models.  Peirce recognized in Darwin model, the very capitalistic model of the market. He saw it as the expression of the Gospel of Greed submerging the end of the 19th century. Peirce was not satisfied with it and proposed another model that goes further into the evolutionary spirit, he question the very basis of the notion of fixed laws of nature and proposed an evolutionary model of evolution of the laws of nature along the Aristotle notion of habit taking.  Note that the brith law system is an empirical evolutionary system of laws where laws are constantly re-examined in practical cases by judges.  It is an evolutionary social habit systems.  Peirce replaced the notion of fixed law of nature by the notion of evolution of natural habit which are gradually stabilized in special circumstance that are themself stabilized.  Here the notion of radomness also play a great role but at a much lower level than the model of Darwin but most importantly Peirce want to replace the gospel of Greed by a Gospel of Love in the core construction of the universe. The ideas of Peirce came partly from the German romantic movement (Kant, Goethe, Schelling, Hegel) and in France the movement dating back to Main de Biran on the role of Habit taking that was further developed by Ravaisson (On Habit) and lead to Bergson (Evolution creatrice) was also going in the same direction.  All these movements were trying to depart of the purely mechanistic model of the universes.  These later ideas were mostly forgotten because of many social events that have shaken Europe and so the evolutionary thinking did not developed further these revolutionary ideas but were developed mostly on the basis of Neo-Darwinian.  But what has been explored and could be explored on this basis has created both in physics and in biology a situation where these ideas now can flowrish.  Biology, physics and psychology all need a common shift in paradigm and I see this paradigm shif as more important than a scientific paradigm shift.  I see it as triggering of the leading role of a new form of anthropological philosophy along the line forseen by Dilthey and the philosophers life of teh 19th century.  I think that philosophy will return to its cosmogonical phase in a new way.

  • Thierry De Mees added an answer in Dark Matter:
    What is the formula for spin independent elastic cross section of dark matter particle scattering off a nucleus?

    Recently I have been trying to calculate the spin independent scattering cross section for direct search of dark matter for a particular dark matter model. I came across several papers where the formula is given. In some cases the formula is given for NUCLEUS and in some cases for NUCLEON. And at the same time in some papers there is a reduced mass term [arXiv:hep-ph/0307185] and in some cases it is tad different [Prog. Theor. Phys. 126, 435,(2011)]. I need spin independent cross section calculated per nucleon basis. 

    Thierry De Mees

    @ George: So, you say that totally massless stuff is accelerated by Newtonian gravity. How really funny reasoning you have about Newton's laws... I give up... That's what you get with nowaday's education...

    Concerning the alleged black body curve and the heat theory of Kirchoff: see Robitaille's comments annexed. Disillusioning!

    "Structure growth in a period long before the existence of the first gravitationally bound objects" That's a pure invention without any ground, only obtained by a multitude of very indirect assumptions and poor reasoning. Nothing to do with any observation.

    Instead, the missing windings of disk galaxies prove that structure growth did not happen very long time ago, "before the existence of the first gravitationally bound objects".

    And clusters can't get structured before the individual galaxies got.

    "Dark matter" and "dark energy" are sheer nonsense and don't exist. Moreover, neither "dark matter" nor "dark energy" are needed in order to solve the alleged issues.

  • Gustavo Braga asked a question:
    How we setting the term "rural"?

    How is the better worldwide definition of the term "rural".

  • Simon Sattler added an answer in SDS-PAGE:
    Why do I see a smear in my SDS gel after staining with instant blue?

    At the moment, I'm struggling with a very basic technique. I want to run proteins from lysed T-REx HEK293 cells on a SDS gel. However, instead of sharp protein bands I just see a smear after staining it with instant blue.

    I'm using precast gels (4-20%) and I also tried different buffers. At the moment, I'm using RIPA buffer (Tris buffer with NaCl) + 1% Triton X + cOmplete Mini Protease inhibitor tablet. My protocol for lysing the cells is the following: I remove the media, place them on ice, wash with ice-cold PBS and scratch the cells from the flask with lysis buffer. Subsequently, I perform three freezing-thawing cycles on dry ice and in a 37C water bath. In the end, I spin the cell debris down at 14,000rpm for 10min and use the supernatant for my gel. I boil a fraction of the proteins with SDS lysis buffer before I load it on the gel.

    I haven't faced this problems before, although I was working with these cells for quite a while already.

    Many thanks for your ideas!

    Simon Sattler

    Thank you all for your help! I solved the problem by changing several different bits of my protocol. If the details may be helpful for you, please let me know and I'll forward them. :)

  • Vasile Surducan added an answer in Reactive Power Planning:
    What is actually reactive power?

    From the basic engineering itself this question has posed me lot of trouble. The main reason is that there is lot of explanation available and few contradict each other. For example, one explanation was it is the medium through active power is transferred, if that is the case then what about DC power transfer? 

    So here i would like to know your opinion on the concept of reactive power and would like to discuss each and every view so that i can have a clear cut understanding of 'real REACTIVE POWER'. 

    Vasile Surducan

    Hi Jose,

    The current is never in phase with the voltage at the output of a classic (no PF correction) solid state dimmer. The dimmer is a non linear load by itself.  To have unity power factor, we assume both voltage and current sinusoidal. The current is not sinusoidal during the dimming process, hence the angle displacement...In fact the current is distorted, so the term "fundamental current" for a dimmed load keeps only the periodicity aspect and loose the sinusoidal one.

    Sorry but today I do not remember a better answer, but I'm waiting to read it :)

  • Christopher J Walker asked a question in Antibodies:
    Does anyone know of a good N-terminal antibody for ARID5B?

    I have tried two commercially available antibodies: The first is raised against a.a. 389-418 and it gives a prominent non-specific band at about 40kDa. The second is raised against a.a. 77-126 and only gives a band at ~25 kDa. Thank you for any responses. 

  • Nisha Wadhwani asked a question in Fatty Acids:
    How to express/calculate fatty acids represented as g/100g fatty acids (relative proportion) in mole percent (mol%) ?

    Analysis of fatty acid methyl esters (FAME) has been done by GC.

    How do we calculate FAME in mole percent using the MW of the fatty acids?

  • Patricia Rodriguez de Gil added an answer in Model Selection:
    How can I refuse some category of questions?

    Now, I check the question about one hours and am very tiered to cancel some categories of questions such as the usage of SPSS, R, Matlab etc. If I need this situation, I ignore the questions. Tell me the good advice. On the other hand, I'd like to accept such as the discriminant analisis, collinearity and model selection.

    Patricia Rodriguez de Gil

    Hello Dr. Orlik! I think you brought up a great point. I have not been in RG for a long time, but yes, I have also noticed that sometimes some questions come up frequently. One is, for example, asking for guidance on how to conduct a Logistic Regression analysis. I have encountered this question several times. While again, all questions are valid and valuable (in my opinion), I think that RG should have a section of, say, most frequently questions asked and the most voted response so that we could go to this section first to see if there is something about our question that has been already responded satisfactorily. Some professors here in RG have taken some action on this, for example, in one thread, one professor let people in the thread know that he had started to gather all the information and resources on the topic discussed so we RG'itas (this is my nickname to us RG users, not his :)) could get help on the topic.I thought that that was incredibly helpful and incredibly generous of his time.

  • Mikael Kerleau added an answer in Size Exclusion Chromatography:
    DTT or TCEP?


    In order to purify a protein, we want to use a size exclusion column (we have a superdex 16/600 200 pg) helped by a HPLC system.

    In the buffer, would you use DTT or TCEP as reducing agents?
    Is there any important differences between those two when used in such column ? (interaction with the matrix for instance)

    Thanks for your time!


    Mikael Kerleau

    Thanks for the answer !
    I guess I can use TCEP now.

  • Jan Ivanouw added an answer in Factor Analysis:
    How can we decide on the method (refined or non-refined) for calculating factor score after conducting factor analysis?

    My study involves conducting an exploratory factor analysis using the principle component method and oblique rotation technique.

    How do I choose between refined ( Regression Scores, Bartlett scores) or unrefined (Sum Scores by Factor, Sum Scores -Standardized Variables, Weighted Sum Scores) methods for estimating factor scores ?

    What kind of impact does my sample size have on my decision ?

    The refined techniques, if I'm not wrong, return standardized values which might be an issue for the subsequent use of these factors in logistic regressions, given other variables are not standardized. But since these methods attempt to retain relationships between factors, I'm inclined to use these over techniques like weighed sum scores.

    Jan Ivanouw

    First, I wonder what is your research problem? Depenting on this, principal component analysis might not be the best method.

  • Pooyan Nikeghbali added an answer in Pipeline:
    Does the negative pressure prevent the flow to transmission in pipeline or not?

    I modeled the pipeline system in the waterGEMS software. In this model I have a pipeline with length of 50 KM. We need 722 lit/s in this pipeline. At the Kilometer of 10+000 to 15+000 the ground elevation is higher than the HGL. The program alarm the negative pressure in this location but the discharge flow is desirable and equal to 722 lit/s. Is this possible or it is the program errors?

    In this distance the maximum ground elevation is 1632 m and the HGL in this point is 1629 m.

    Pooyan Nikeghbali

    Dear Bhupendra Desai

    As the figure is shown, this pipeline dose not have any pump or suction and transfer the water just with gravity. The up-side of pipeline is a reservoir with infinity capacity and the down-side is a tank with a FCV valve before the tank to control the discharge flow.

    I thought, may be this phenomena behaviors as an air-pocket with not full-blocking (the fluid flows as a free-surface) but we don't have air leakage in the model.

    Best regards