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  • Ahmed Alchalaby asked a question in Inkscape:
    Problem with importing CAD files in the Comsol

    when I am trying to import cad file (generated by vectorization an image in inkscape software) as a geometry in comsol 4.3b, an error message "singular edge detected -Edge: 1" appears. attached files contain the SEM image and its .dxf file. Any one has an idea???


  • Jorge Vera-Otarola added an answer in RNA:
    How to remove the RNA from the purified protein?

    I have tried to remove the RNA from the purified protein by using PEI,but the RNA didn't remove completely

    Jorge Vera-Otarola · Institute for Research on Cancer and Aging, Nice

    Hi Li,

    I guess that the system to purify proteins that you are using is bacteria. Whether you are purifying proteins from bacteria the best is benzonase which is a strong nuclease in order to degrade DNA and RNA without any protease activity detected from sigma. good luck!

  • Panayiotis Panayides added an answer in Composites:
    Is any one familiar with Principal Components Analysis and Cronbach's alpha?

    I have wanted to explore the idea of identifying a latent variable through PCA in two questions about the timing and quantity of adherence to medication. The PCA comes out very well, including with split-sample validation, however the Cronbach alpha is very low (<0.45), which is almost to be expected as each of the two questions should act like a single-question 'sub-scale'. As this is not going to be used as a psychometric scale but just a 'composite variable', I'm wondering if I can just go ahead and use the resulting factor-variable/composite in analysis. Can any well-informed data-analysts guide me on this? Thank you. 

    Panayiotis Panayides · Secondary Education, Cyprus

    Two items are too few to make a strong measurement scale. Alpha is a measure of the item interrelatedness but with just 2 items it can be expected to be very low. The problem is not on the value of alpha but on the number of items you are using.

    For more information on alpha please have a look at "Coefficient Alpha: Interpret with caution". You can find it and download it in my page,

  • Mpho Maleka asked a question in System Identification:
    System identification

    How do i go about with system identification of a multivariable hydraulic servo system

  • Akinwumi Amusan added an answer in Ellipsometry:
    Does anyone have an idea how to model thin Ag film by ellipsometry?
    I am taking thickness measurement of ALD silver films by spectroscopic ellipsometry, usually the expected thickness should be less than 10nm. However each time, I fit the psi and delta data with the various Ag models in the database, I get different results. How do I know the correct thickness?
    Akinwumi Amusan · Otto-von-Guericke-Universität Magdeburg

    Thanks, the article was quite informative.

  • Davor Krasic asked a question in Cities:
    What are the daily trip rates (number of motorised trips per household or person) in different European countries or cities?

    Daily mobility differs across countries and cities in Europe. Can you provide the data  

    for your country or city which are results of traffic surveys conducted in last 5 years? All European countries and cities are welcome.

  • Domenico Regonini added an answer in TiO2 Nanotubes:
    Does anyone have any idea why TiO2 nanotube films anodised in pure EG always peel of compared to other electrolytes (organic electrolyte)?

    Sometime ok but sometime not, so it is hard to make it as a control sample (reference) for application (e.g. photocurrent or photocatalytic activity).

    Domenico Regonini · Empa - Swiss Federal Laboratories for Materials Science and Technology

    Hi Mustaffa, one possible reason for the film peeling off may be that you are anodizing at a too high potential? what is the voltage you are applying during the growth of the film? or maybe you are anodizing for too long time? which conditions ae you using? also, the maximum anodizing potential that you can apply is not the same for every electrolyte.  Finally if you are aiming at having a good reference sample and reproducible results I would suggest you to always add a constant and small amount of water (few weight %) to the organic electrolyte. This makes the process more reproducible because by adding water you are providing more oxygen for the oxidation of Ti. if you rely only on the moisture adsorbed by the ethylen glycol (EG) or even worst only on EG as oxygen source then you will have difficulties to make your process reproducible. hope this helps, cheers

  • Can anyone explain the effect of X-Ray on seed mutation breeding activities ?

    I need to use X-ray in seed quality test in gene bank, but i need know if this seed affected with X-ray irradiation or no.

    Cristiane de Carvalho · University of Sorocaba

    I used X ray for seed quality and nothing happened (any type of mutation even physiological effects). Seeds germinated very well. In the lab where I worked everybody does and we never had problem because the radiation is very low. We worked with soybeans, beans, tomato, pepper, albergine, tabebuia, maize, etc.

    Mutation will happen if you irradiate with gamma rays.

  • Jean Rene Grezes added an answer in Alumina:
    Do cells uptake alumina nanoparticles?

    Does anyone have a reference about the in vitro cellular uptake of aluminum and alumina nanoparticles?  Thank you for the help.

    Jean Rene Grezes · Laboratoire Prive

    Dear Trevor,

    please give more infos about the kind of cells to the answerers. Why?

    For in vitro investigations you can use human lines  or animal lines. What organs will be considered as cells source?

    Please read the following booK :




    and reformulate your question pleae.


  • Judit Erchegyi asked a question in Cations:
    I have received an e-mail that Dr. Franzyk sent me the full text of his paper I requested but I can't find it, can I get it to my e-mail address?....

    Solid-phase route to Fmoc-protected cationic amino acid building blocks.

  • Amin Hosseini asked a question in Abaqus:
    Properties of cohesive interface in abaqus

    In the cohesive interface behavior, what is the default enforcement method?

    how it works?

    and whats the coefficient of friction after full damage of bonding?

  • Tiago Canal Jacques added an answer in Extremities:
    Does anyone know a valid metod to measure power in a single leg?

    I need to measure muscle power of a single inferior extremity. And compare with the other, I would really appreciate if someone have some information to share.

    Tiago Canal Jacques · Universidade Federal do Rio Grande do Sul

    Asymmetries could exist between legs and such approach (divide by 2) could not be the the most appropriated method.

  • Denis Havlik added an answer in Puzzle:
    How do you randomize a 9 x 9 grid with 81 cells to populate between 10 and 21 numbers in Visual Basic?

    I am trying to populate a Sudoku grid by placing randomized numbers between 1 to 9 throughout the 81 celled grid. I already have a solver that solves a puzzle but I want to use a button to randomly populate the grid to start a new puzzle each time the button is clicked. I am not fluent in VB code and I have been searching for an algorithm to complement my needs. I used backtracking to solve the puzzle but I need to use random to populate the grid for the beginning of the game. I have attached a copy of my public class and my backtracking algorithm. How do I get random numbers to populate my start button?

    Denis Havlik · AIT Austrian Institute of Technology

    Ha-ha, sounds like fun. According to some web articles, it may be enough to generate just one valid solution and then shuffle it according to a couple of rules in order to generate other solutions. See e.g.:


    Generating one particular solution is really easy, see Wikipedia article (last part):


    So it's basically "start with this solution, shuffle according to the rules above for a while and that's your starting point". I wonder if one can generate ALL possible Sudoku puzzles starting from a single solution or just a subset?

    (If not, the "backtracking" algorithm seems to be straightforward.)


    From there on it's a question of taking some of the numbers away and making sure the puzzle can still be solved in only one way...


    Yo may also find this paper interesting - it describes how to give a rating to a puzzle http://zhangroup.aporc.org/images/files/Paper_3485.pdf

  • Michael Ellington added an answer in EViews:
    How do I perform sequential test for type of linearity?

    Dear everyone,

    In the paper I attached below, there is a  sequential test for type of linearity, table 5.

    The purpose of this test to find out LSTAR or ESTAR. However, I cannot perform this test.

    Anybody please help me to do it, I prefer to R programme or Eview software.

    Thank you very much.

    Michael Ellington · University of Liverpool

    I have not looked at the paper you attach but am familiar with the procedure.

    To test for this type of non-linearity we use a third order Taylor approximation (since the smoothing parameter of the transition function is unidentified under the null). First you specify your linear model eg: y_t = b_0+b_1*y_t-1+b_2*x_t-1

    Given you have your transition variable let's assume its y_t-1

    Then your initial test equation is the linear regressors (excluding the intercept) and the cross product of the transition variable, the squared transition variable and the transition variable cubed (i.e. y_t-1, y_t-1^2 and y_t-1^3)

    more formally:

    y_t = linear model+B_1'w_t-1*y_t-1+B_2'w_t-1*y_t-1^2+B_3'w_t-1*y_t-1^3

    where w_t-1 are the regressors in the linear model.

    Then H_03 tests the joint significance of the parameters in B_3'w_t-1*y_t-1^3 with the null they =0.

    Once tested, H_02 tests the statistical significnce (in the same way as above) of the parameters B_2'w_t-1*y_t-1^2 given that B_3'w_t-1*y_t-1^3=0

    then H_01 test the statistical significance (in the same way as above) of the parameters B_1'w_t-1*y_t-1 given that B_2'w_t-1*y_t-1^2=0

    The test that has the lowest p-value informs you of the functional form of the transition function. (if H_02 provides the lowest p-value the result suggests either an exponential transition function or a quadratic logistic function; lowest p-values from H_03 or H_01 suggest a logistic transition function.

    This estimation is easily done in Eviews using least squares estimation and then performing an F-test testing the joint significance of the parameters B_i'w_t-1*y_t-1^i for i=1,2,3. This is sequentially tested down to i=1 given that the parameters you have tested previously are equal to zero.

    Hope this helps.

  • Peter T Breuer added an answer in Combinatorics:
    Which operations can be constructed using only xy and x+y+z?

    What method can I use to charcterize which operations repeated multiplication xy and 3-input addition x+y+z are able to construct mod 4, or mod 8, or .. or mod 232?

    I suspect the answer is all the operations `like them', which are those taking all-zero inputs to zero, all-odd inputs to an odd number, and all-even inputs to an even number.

    I know that all the (8) functions that take zero to zero, odd to odd and even to even mod 4 can be built as a combination of multiplications and 3-input additions. Perhaps multiplying and adding those is enough to construct every operator table with?

    Any clever ways to go about this? I am trying symbolic computation to generate the orbits of  "x" and "y" under substitution in the binary operators xy and x+y+z mod 4.

    Peter T Breuer · Birmingham City University

    Strangely, I see 1436 operator tables constructed by xy and x+y mod 4. That's multiplication and the ordinary addition, not the more rarified three-input addition.

    Shouldn't these plain old operations construct all polynomials in x,y with 0 constant term? Going by the coefficients, there should be 415 of them (15 coefficients taking the values 0,1,2,3). But I suppose there are polynomials with different coefficients that are functionally equal, since there are divisors of zero mod 4? The difference might be zero mod 4, but have nonzero coefficients? 

    Yes ... 2(x-1)(x+1)x is zero on all values 0,1,2,3. That's 2x3+2x=0.. That and 2y3+2y and 2(x3+x)(y3+y)  can be added to any multinomial to get the same function again, by value. So every multinomial has up to 8 alter-egos right there.

    And surely 2(x-1)(x+1)(x+2) also is zero everywhere? Yes. It's got friends 2(y-1)(y+1)(y+2) and 2(x-1)(x+1)(y-1)(y+1)[xy or x(y+2) or (x+2)y or (x+2)(y+2)] . That's another 26 alter-egos for a total of 23+6=29 so far. Perhaps I've missed some more? Can anyone count the number of functionally distinct multinomials in x,y mod 4?

  • For performing fracture toughness (SENB samples) test on epoxy samples can we use the mechanical testing machine with load cell of 10KN ?

    Single edge notch bending test has to be conducted according to astm D5045. sample with dimensions 6X12X60.

    Paul Deconinck · Ecole Nationale d'Ingénieurs de Metz

    If you have enough samples and if you have no idea of the  fracture load I would suggest to do a preliminary test with your 10kN cell. Then if this fracture load ranges from 1 to 9 kN you can use this cell. This interval, representing 10 to 90% of the cell capacity, is the common confidence interval of most load cells. If not, you should choose another load cell adapted to the value of the fracture load.

  • Steingrimur Stefansson added an answer in Vitamin K:
    Why PT or INR is a better measure for evaluating the effect of vitamin K on coagulation process than PTT?

    As we know, vitamin K is essential for the formation of factors 2,7,9,10 in the coagulation cascade, which factor 7 participates in extrinsic pathway, factor 9 participates in the intrinsic pathway and factors 2 and 10 participate in the common pathway
    From the above information we can say that vitamin K is essential for both extrinsic and intrinsic pathways. But as we know, for evaluation of effect of vitamin K on coagulation process, we measure PT or INR.

    Steingrimur Stefansson · HeMemics Biotechnologies Inc

    I forgot to add that PTT also activates the intrinsic pathway starting with XII, and XI, which are not Vit. K dependent proteinases, so it can be less sensitive to Vit. K deficiency or warfarin.

  • Nihan Şahin added an answer in Touchdown PCR:
    How should I calculate a touchdown PCR reaction with a low dna quantity?

    I have an average of 1.5 ul/ml total dna quantity on my vine dna samples. In this case, how should I calculate a touchdown PCR reaction for 20 - 25ul?

    Nihan Şahin · Namık Kemal Üniversitesi

    Yes i have 1.5ng/ul DNA. I confused about samples concentrations,  but if 3ng/ul is enough, i can optimize my samples for this value. 

  • What is the chemical composition of essential oils of globba species?
    Three globba species studied by gc/ms.

    Hi Channappa

    The chemical compositions of the essential oils of three species of the genus Globba (Zingiberaceae) (Globba cernua Baker, Globba marantina L. and Globba ophioglossa Wight) were analyzed by GC-FID and GC/MS. β-Caryophyllene(19.3-24.2%) was found to be the major compound of the oils. Other major compounds detected in the oils were α-humulene, (Z)-nerolidol and (Z,Z)-farnesol. For more please read at the following link.

    Best regards

  • Is there a method to estimate bond strength parameters required to use ABAQUS cohesive interaction functionality to simulate metal to metal bond?
    I am trying to simulate adhesion of metal sheet articles to forming dyes during SMF. It is called galling. I have a problem defining the required parameters to feed into ABAQUS, i.e Knn, Kss, Ktt. Do you have any idea?
    Amin Hosseini · Amirkabir University of Technology

    You can try default enforcement method which is provided by abaqus

    you can get some idea from it

  • Encapsulation in calcium alginate beads

    Hello I am currently working with the encapsulation of laccase in calcium alginate beads. I am also following the optimised conditions of my previous graduate collegue. So she optimised the highest encapsulation yield using 1.5% alginate(w/v) with a protein loads of  1.5mg/mL (1:10w/w, protein:alginate ratio). Now the protein that we get from our ultrafiltrate enzyme, we  obtain  from 1g of  lyophilised enzyme-15mg protein. Therefore, according to my understanding i should add 0.1g (containing 1.5 mg protein) powder to 1 ml of 1.5% alginate (to get a ratio of 1:10 w/w-protein to alginate). The problem with this is that it is not a homogenous mixture, even if i dissolve this 0.1g in 1 ml water and then add it to the 1 ml alginate, it is very viscous and has numerous lumps. I really need  help with this. Thank you

    Enrique Alarcón Gutiérrez · University of Veracruz

    Hi Kaur,  What is the pH of the alginate solution? I think you can try increasing the pH of your algintae solution and warming up the mixture. Other thing is changing the alginate concentration, 0.8%, mixing  with the enzyme and adding the other %. I hope it works, bye.

  • Loretta Stanford added an answer in Muslim Women:
    Is anyone studying Muslim women in sport?

    Anybody working on muslim women, sport and leisure in Europe, and how local governments are managing cultural and religious diversity in a gender perspective? I'm looking for qualitative studies carried out in South EU countries. 

    Loretta Stanford · Northcentral University

    Your most welcome, Maria. I am so pleased to find others who are interested in gender studies.

  • Hanno Krieger added an answer in Iron:
    Iron [!] Sticks ''on the Road'' [20cmLength, 0,5cmWidth, 0,01cmThickness]

    I'll enclose the Picture of the Sample of Iron Sticks appearently casually distributed along the Streets of the City where I live, and along the Streets of other Cities of the Region where I live [I've seen them there, as well]. I believe they are causally [!] there. In your Opinion, who is disseminating/distributing them, and why? [I have developed few Hypotesis]. Do any of you have had the same Experience in the City where he/she lives, or which he/she has visited? Many Thanks in Advance for your Comments. Solarity and Happiness inside/outside to Every1.

    Hanno Krieger · retired from Justus-Liebig-Universität Gießen

    Dear Francesca,

    my answer should meet your question. But plaese forgive me, I didn´t understand your issue. That´s the reason for my reduced irony.

  • Kim Trang Nguyen added an answer in SAP:
    Does anyone know of a proposed structure for the transition state when passing from TSAP to SAP geometries for GdDOTA complexes?

    I want to know if someone has published the structure of the transition state for GdDOTA complexes when passing from TSAP to SAP geometries.

    Kim Trang Nguyen · California State University, Los Angeles

    Hi I am not sure if you know how to use Gaussian  software, because you can predict the transition state of chemical reaction by Gaussian program. If you don't know, try to learn it. Sometimes Gaussian is very helpful for your research.

  • Hamed Farhadi asked a question in Genetic Programming:
    How to implement Linear Genetic Programming.

    Anyone can recommend any software or codes to implement linear genetic programming?

    Thanks in advance.

  • Abedallah M Rababah added an answer in Teamwork:
    How to build a teamwork culture in universities?

    Building a conductive environment to teamwork in universities is a process requiring a plan and specific activities to support the teamwork solidarity.

    Abedallah M Rababah · Jordan University of Science and Technology

    Dear @Mahfuz, you already got very helpful points of view to increases collaboration and build teamwork culture in universities; I think that personality and ability to work in team should be learned at early stages of school and childhood.

  • Simon Penny added an answer in Physics:
    Can we mathematically model consciousness?
    We have seen that AI, which was supposed to be a failure, is coming back with
    gusto on the back of multi sensor robotics and possibly androids with quantum computers. There is some mysterious counter intuitive behaviour in the sub atomic world which seems to suggest inanimate objects do sense the external world.
    It would be nice to know the views of experts from different fields, such as math, science, psychology, sociology, cosmology on this intriguing subject. One possibility
    that comes to mind is if probability is actually such a model, as it does incorporate
    Simon Penny · University of California, Irvine

    Dear Jonathan,
    thankyou for your reply, and for addressing these points.

    > "I think we avoid circularity just by being absolutely rigorous about what we think we are trying to do."

    is that enough? Its a start for sure. But I suspect that we can easily remain locked into styles of thinking. To take the analogy an equation, simply - we need ways to invert terms and ask -what if? But even so we remain - in a Goedelian way - locked into a worldview. There is nothing more difficult - as a student of mine succinctly observed long ago - than denaturalisation.

    > "Models in computers can at best tell us about the internal consistency of a hypothesis about the brain - whether it actually predicts what we think it predicts. Their job is to eliminate poorly formulated hypotheses. But they have no role whatever in testing whether a hypothesis about the brain is invalid or viable. You can only do that by observing or manipulating brains."

    A seemingly obvious point beautifully put! Humberto Maturana said much the same.

    > "To my mind the new agenda needed is very simple. It brings together the rigour of philosophers who actually understood science (because they invented it) like Descartes and Leibniz, and the rigour of modern condensed matter physics. We need a biophysical account of thinking that obeys the laws of locality of all other physics."

    Are you calling for the _rigour_ of "modern condensed matter physics" or to bring biology 'down' to physics? If the latter, this is to endorse downward causation. If so, what do you say to the anti-reductionist emergentists and systems theorists? (I do not feel that it is necessary to bring all things down to the level of basic physics in order to establish rigorous knowledge claims. )

    > "Current neuro-scientific models do not do this - they have no basis in physical science. They dodge the issue."

    woo hoo! you have your boxing gloves on! That is a generalisation, for which you presumably will cop some flack. But -there are so many levels to 'physical science' and if you're not a reductionist, then they do not need to correllate.

    The remainder of your reply deserves a thread of its own I think. :)
    > "Our idea of 'matter' is a convenient fiction."
    > "This is why I am sceptical, I am sorry to say, about talk of embodiment and embedding. These terms have no use in a rigorous analysis of our relation to the world. They belong to the fiction of materialism. There is nothing to do the embodying or to embed in."

    as Samuel Johnson said - "I refute it thus" . I guess that puts us on opposite sides of the philosophical fence :) so I can't go with you into the land of MD. But I do have a question about E.

    >"E is only the most proximal component and so is local within the brain. The law of locality of physics is essentially the law that E is always as local as can be ascertained. "

    Why must E be local? I worry about fundamental attribution error. Doesn't searching for the 'E neuron' drag us back into a style of inquiry that searches for objects and structures, when E might be an emergent property of networks, tides of neurotransmitters, or resonances in phase-locked loops?


  • Stefan Gruner added an answer in Nature:
    What evidence would be needed to prove Nature is intrinsically mathematical?

    As opposed to mathematics being an invention, what evidence would convince us that mathematics is there already in Nature?

    Stefan Gruner · University of Pretoria

    @Steve, RE: "what evidence would convince us that mathematics is there already in Nature?"

    The short answer is: nothing would ultimately convince us.

    The long answer is:

    Mathematics is a Language. Nature is Matter and Energy. Those are two completely different ontological categories --- different realms of being.

    With Mathematics we /speak  about/ Nature. If Mathematics were "in" nature, as you suggested, then I should be able to inflict causal effects onto natural entities and processes simply by "doing Mathematics" --- such a miracle, however, has so far nowhere been observed.

    Look into your microscope to see the smallest things: Things you will see, Mathematics you will not see. Look into your telescope to see the farthest remotest things: Things you will see, Mathematics you will not see.

    Likewise, you will also not see "English" when you look through your microscope or telescope, nor any "Language". You will also not see "Natural Laws" or "Laws of Nature" --- you will always only see things with your eyes.

    By the way: You will also not see "English" when you look into a book written by Shakespeare. What you actually see in Shakespeare's book is: Ink on Paper.

    Thus the question arises: what is the meaning of your word "in"? Is my mind "in" nature? Is my mind included in nature? Is the physical law, E = mcc, "in" the nature as soon as it is in my thoughts and in my mind?

    Ultimately, your question amounts to: Are the Platonic Forms REAL, and ---if yes--- what type of "Reality" is this?

    For further and deeper philosophical thoughts in this context, I can strongly recommend a classical, well-written book by Victor Kraft (1947) ---see the link attached below--- in which the relation between natural experience and mathematical description is discussed.

    I'm not saying that Victor Kraft "is right" --- but what I am saying is: his book is a very good starting point for an intellectual journey into the field to which your question is related.

    For additional orientation I should add that Victor Kraft had been philosophically related to the famous "Circle of Vienna"; he was thus /not/ a "mathematical Platonist" (such as, for example, Kurt G"odel or Roger Penrose).

    [Personal communication via http://www.researchgate.net, 16-Sept-2014]

  • How do I convert the selenium dioxide to selenious acid?

    See above.

    Michael Nazarkovsky · Chuiko Institute of Surface Chemistry, Kiev, Ukraine

    To all previous ones: Mr. Selvaraj asked about a detailed description of the acid sythesis.

    SeO2 (110.96) + H2O (18.02) → H2SeO3 (128.98)

    The preparation technique as follows: dissolve SeO2 in little amount of water (in porcelain mortar), thereupon the evaporation of the solution follows. NB: this solution found in a mortar must be avoided ingressing of dust in the course of the evaporation.

    The evaporation is carried out on the bain-marie until the crystallization occurs.

    After cooling H2SeO3 formed has to be filtered using a glass filter and recrystallized in water once again to provide an appropriate purity of the product.

    The recrystallized H2SeO3 has to be dried in filter paper accurately wringing out the residual water.
    Keep the acid in a vacuum exsiccator over KOH during a three-four days time (NOT MORE, because distinct dehydration of the acid will take place).

    Your welcome!