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  • András Bozsik added an answer in Renaissance:
    Does anyone know who the artists are the first to introduce contra (inverse)-perspective in painting art?

    Whether it happened before or after Renaissance time?

    András Bozsik · University of Debrecen

    Deaf Christopher,

    Certainly, you are right from point of you of the intention of painters and the cultural/symbolic demands of the age. However, Doko’s question did not touched either artistic value or symbolism of delineation. It is rather a technical/historical approach.

  • How do you effectively assess the societal value of a given redundant building or site? With the intention for adaptive re-use of the site?

    When determining whether a redundant building is to be retained, demolished or adapted, how can it be effectively assessed from a social and cultural perspective to determine its value to the community?
    Note: not only historically relevant buildings but industrial or outdated commercial buildings. 

  • Vinesh Kumar added an answer in Solid State NMR:
    Can anyone suggest a solid state nmr method for structure elucidation of a polymer?

    Is it possible to use solid state nmr to determine the monomer, dimer, trimer,etc of insoluble polymers?

    Vinesh Kumar · Gautam Buddh Technical University


  • Senthilvel Vasudevan added an answer in Habits:
    What is the best method to measure habits of mind for pre-service science teachers?

    I want to measure the habits of mind for pre-service science teachers inFaculty of Education and Iam trying to find the best tool for that.

    omda mohamed

    Senthilvel Vasudevan · King Saud bin Abdulaziz University for Health Sciences


    The best method to measure habits of mind for pre-service science teachers, conduct some research related to that, then you would come to a conclusion on that.

    Your question is not a clear one.  Particularly what you want?  that is not mention clearly.  Any way, my anster would help to you.  I think so.

    Kindly refer the following links:




  • Vinesh Kumar added an answer in DPPH:
    Which technics is efficace to determinate antioxydant activity of essentiels oils?

    which methodes are efficace ORAC or DPPH tests?

    Vinesh Kumar · Gautam Buddh Technical University

    DPPH mostly used.

    you can also read this paper

  • Yun Li asked a question in MCAo:
    Can Diff-Quik be used to determine the extent of cerebral damage in MCAO?

    Quick question, can the commercially available staining method Diff-Quik be used to determine the extent of damage in brain slices from MCAO mice? It seems like a really great way to stain cells, and I just want to see some nuclear diffusion or things like that. Really basic morphological stuff.  

  • Khaled Atik added an answer in Traffic:
    Are there any survey articles about multi-agent simulation of road traffic?

    i need every thing about (survey articles) regarding Multi-agent  simulation of road traffic / transportation

    Khaled Atik · Research Center on Scientific and Technical Information

    Hello karen,

    thank you very much for the clue, keywords matters too, i will consider it in my future searches


  • Mohamed El Naschie added an answer in Space Time:
    Are space and time warps really possible? Is this proven?

    I'm wondering if I can go back to my old days when I was a kid. Or maybe if I can reverse the time so that everyone mistakes can be corrected. Is there a theory about this?

    Mohamed El Naschie · Alexandria University Alexanderia Egypt

    DEAR JOHN- MY CURRENT RESEARCH  and understanding is as follow ; Quantum Entanglement  is real .I see it as a topological zero measure geometry of a Cantorian space time   on the quantum level. if this is correct, and it is correct then worm holes  of EINSTEIN Relativity are large scale quantum relativity ENTANGLEMENT . Thus for sure these classically strange things are possible for say an ATOM .SOLVING THE TECHNICAL problems for a  a human may take 100  years or 1000 years or more but it is exiting to think it is at least not impossible 

  • Abdelhalim Zekry added an answer in PEDOT:PSS:
    How does PEDOT:PSS act as a hole extractor/electron blocking layer in organic solar cells?

    Is it only the work function and relevant HOMO LUMO  energy level alignment that makes a pedot:pss layer act as a hole extracting layer? In that case, with different energy level alignment can it extract electrons as well? or is there an additional mechanism for blocking the electrons? For example how the hole mobility and electron mobility of pedot:pss would compare?

    Thank you.

    Abdelhalim Zekry · Ain Shams University

    Dear Waranaha,

    I would like to add to the answer of the research gate college Ghosh. the energy differences between the conduction bands and the valence band of two contacting materials are a necessary bu not sufficient condition  to act as an extractor of e.g. holes as in the case of  PEDOT:PSS. The second condition is that the material must easily transport the holes, which means it must be good conductor of holes to deliver them to the metallic electrode. To demonstrate the argument assume the material satisfies the energy difference condition but it is insulating,it will not function properly. So, the thoughts of Waranatha are okay. 

    wish you success

  • Daryn Dyer added an answer in Likert Scale:
    How would you use a questionnaire to measure contextual and behavioural aspects of aggression in in-group settings?

    I am conducting a behavioural/observational analysis of in-group violence in communities which use bare-knuckle boxing to settle disputes. I am using a likert scale questionnaire to get the opinions/attitudes of 3 boxers with expert knowledge of the area by showing them 3-minute videos of the fights and then inviting them to answer the questions.

    Does this sound like a valid method? How do I know if my scale is valid/reliable since I made it up myself? I based the questions/statements on current theories of in-group aggression. I can't find anything else to compare this methodology to as I believe it's quite unique.

    Also, is three raters enough? I'm working of the fact that behavioural studies usually use around 2-5 expert raters to give their observations. But I'm not sure if that's what I'm doing here exactly.

    I'd really appreciate any advice on this issue, thanks.

    Daryn Dyer · York University

    Buss-Perry Aggression Scale:

    Buss, A. H., & Perry, M. (1992). The aggression questionnaire. Journal of personality and social psychology, 63(3), 452.

    Bryant, F. B., & Smith, B. D. (2001). Refining the architecture of aggression: a measurement model for the Buss–Perry Aggression Questionnaire. Journal of Research in Personality, 35(2), 138-167.

    The first link includes the aggression scale, the second link is for the Bryant-Smith, 2001 article:

  • Guang Jiang added an answer in TRIZ:
    How can I find papers about TRIZ plus: benchmarking and feature transfer?

    I am learning TRIZ plus,including bnechmarking and feature transfer,but I can hardly find such papers, so I wonder who can help me to find some? 

    Guang Jiang · Hunan University

    I will try it,thank you.

  • Ramona Khanum added an answer in Biofilms:
    Are there any non-biofilm forming bacteria?

    I want to know which bacteria do not make biofilm? Some bacteria are unable to form biofilms as successfully due to their limited motility. Can you please share your opinion. 

    Thank you..

    Ramona Khanum · International Medical University (IMU)

    Hi. Though I would like to agree with Mr Filipe's reply, there are many reports of non-biofilm forming strains that are used as controls in biofilm formation and even gene work in biofilm related researches (controlled environments), such as Staphylococcus epidermidis (ATCC 12228). So, is it possible that though conditions permit and the microbe would persist if they did form biofilms, they simply are unable to? perhaps due to their genetic make-up? - for e.g genes involved in producing the required proteins to aid adhesion, matrix production and maintenance are not present/regulated?

  • Oleg B. Gadzhiev added an answer in Hearing:
    How do we use the option "anharmonic corrections" in Gaussian 09W?

    Here i have attached a file which shows the anharmonic correction option available in Gaussian 09W. But i don't know How do we use the option "anharmonic corrections" in Gaussian 09W? 

    hoping to hear back from any one soon.

    Thank you in advance.



  • A.U. Daniels added an answer in Milling (machining):
    How can I mix two different ceramics powders via ball milling without reducing particles size?

    I want to mix two different ceramics powders using ball milling machine. In the same time I need not any reduction or reducing in particles size. How can I do that? I have some suggestions:

    1. Use very small balls

    2. Use very few balls

    3. Use very low speed

    4. Use a short milling time

    5. Do not use high energy ball milling machine

    If one or more of the above suggestions is right please confirm and give more details. Also I need other useful suggestions.

    A.U. Daniels · Universität Basel

    Ball is probably not the best method for blending powders without altering particle size. There is a great introductory article to the topic of powder mixing and blending at: 


  • Peter T Breuer added an answer in Formal Languages:
    How does left recursion affect context free grammar?

    I'm reading about context free grammar and i recognized how to eliminate the left recursion but i did not find out what is the problem with left recursion?? can any one explain 

    Thanks in advance

    Peter T Breuer · Birmingham City University

    (Antonio, I love the idea that "noun phrase" is left recursive! Yes, they should have put np --> relc; relc, np. but without the double evaluation for relative clauses. Forgive my prolog.)

  • Can a line follower robot take soft turning with 100rpm?

    I am preparing a line follower robot without microcontroller and I want it to move with high rpm but it is moving out the line in turnings due to inertia.

    How can I control it?

    And it takes turning by stopping one of the side motors. And I want to reduce one of the motors' rpm so that it will take soft turning like a normal car or bus.

    Can anyone tell me how I can make a circuit with these features?

    Amitanshu Shukla · International Institute of Information Technology, Hyderabad

    After reading the issue, i think there is something which might help. Although feasibility of which am not pretty sure about in your case. It is to let the two dc motors power the wheel and control the direction using a servo motor which only directs the third wheel (free moving) mounted either in front or rear(preferably front) of the robot. 

  • Yohan Pillon added an answer in Gymnosperms:
    Does anybody know any gymnosperm which is an obligate aquatic organism - other than Retrophlylum minus (Podocarpaceae) from New Caledonia?

    In our recent global analysis of all extant gymnosperms we concluded that there is only one obligate "aquatic gymnosperm" taxon among ca. 1000 known species of this ancient plant group. Are there any other candidates? Are there any fossil evidences/examples of "aquatic gymnosperms"?

  • András Bozsik added an answer in Research Projects:
    What result of research project you favor as the best ?

    Different scientist can have different opinion. Please, share your opinion with your peers.

    András Bozsik · University of Debrecen

    Dear All,

    Of course, approach of the truth helps us to live better, happier and more ethically.

  • Tamer Ali asked a question in Homer:
    Homer findGenomeMotif.pl ghostscript error?

    Hello everybody,

    I am running HOMER to find motif for my factor of interest. I should get motifs in many formats line png, pdf and motif formats. unfortunately the script gives the following error message:

    GPL Ghostscript 9.16: Unrecoverable error, exit code 1

    could any one help solving this problem?

    thanks much

  • Kemal Gonen asked a question in Blended Learning:
    What do you think about the effect of blended learning on ESL learners' motivation and autonomy?

    What do you think about the effect of blended learning on ESL (English as a Second Language) learners' motivation and autonomy?

  • Gabriel Ruiz added an answer in Frustration:
    Looking for a B.F. Skinner article, can someone help?

    I find it frustrating to try to complete a one week assignment without this article. I have searched my library resources to exhaustion. It cannot find a place to purchase this.

    Skinner, B.F., (1931). The concept of the reflex in the description of behavior. Journal of General Psychology, 5, 427-58.

    Gabriel Ruiz · Universidad de Sevilla

    My pleasure Paula, Gabriel.

  • Gaci Kamel added an answer in Semen:
    What is the best way to save the semen for a long distance travel?

    I want to know the damage that can be caused to the proportion of the compound when the sperm transport from the farm to the laboratory and What is the best way to save it?

    Gaci Kamel · Le Centre de Recherche en Biotechnologie

    dear humberto thank you very much.

  • Will anyone guide me ATRP method for polymerization of aniline ?

    Atomic transfer radical polymerization method is used to obtain controlled chain polymerization of poly(N-isopropylacrylamide) and others polymers. Will this method is also applicable for poly(aniline) ?

    Abdelkader BOUAZIZ · Univ. Ibn Khaldoun Tiaret

    Dear Sir;

    C=C means a vinylic or acrylic. The amide group does't contain C=C, and if you mean th carbonyl (C=O) this is not a site prone to radical addition. For the benzene ring there is some work using organimetallics or an hybrid clay catalysts to open it but not of the living/controlled polymerization techniques (NMP/SFRP, ATRP, and RAFT/MADIX). There is also some work on controlling step-growth polymerization (polycondensation). For the best of my knowledge conducting polymers still not really concerned by the controlled synthesis, but what is found for this polymers, is that electropolymerization leads to more structured and regular polymers compared the chemical way of synthesis. Regards

  • Hazim Hashim Tahir added an answer in Battery:
    How can I efficiently drive an LED?

    I understand that I can not connect an LED directly to a battery because it will draw too much current. Thus, there must be something else in the circuit to limit the current. What options are there? Are some methods more efficient than others?

    Hazim Hashim Tahir · Ministry of Science and Technology, Iraq

    Dear Colleague,

    Good Day,

    If you follow the attached article you will help you alot. This application note is intended to provide detailed application hints regarding the usage and design in of the
    Infineon® Basic LED Drivers. The selection of external components is shown within this application note.
    Furthermore, different principles of LED driving concepts are explained. 

    the second article is useful too. you can see the rest too.

  • Bouhafs Djoudi added an answer in Solar Cells:
    What is the difference in efficiency in c-Si solar cells with and without surface texturization?

    What is the difference in efficiency in c-Si solar cells with and without surface texturization?

    Bouhafs Djoudi · Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE)

    C-Si surface reflection coefficient without texturization is around 35% in the solar spectral range (0.35_1.2 µm), so this photons loss does not contribute to the photocurrent generation. When the surface is textured (Generally by chemical setup), we obtain an optical confinement which increment the absorption the incident photons in the C-Si bulk. This generates an increase of 35% of photocurrent and the absolute C-Si solar cell efficiency rises of about 1 to 2%. Because the surface of the wafer becomes greater with texturization, the surface recombination growth and the open circuit-voltage drop weakly, but these phenomenon do not compromise the benefic effect of the optical confinement of the silicon surface.

  • Does the creation of mathematical symbols expedite the growth of mathematics?

    It was true that mathematics was done in argumentation and discourse or rhetoric in ancient times. The 6 volumes of Euclid’s elements have no symbols in it to describe behaviors of properties at all except for the geometric objects. The symbols of arithmetic: =, +, -, X, ÷ were created in the 15th and 16th centuries which most people hard to believe it - you heard me write. The equality sign “=” and “+,-“ appeared in writing in 1575, the multiplication symbol “X “ was created in 1631, and the division sign “ ÷” was created in 1659. It will be to the contrary of the beliefs of most people as to how recent the creations of these symbols were.

    It is because of lack of symbols that mathematics was not developed as fast as it has been after the times where symbols were introduced and representations, writing expressions and algebraic manipulations were made handy, enjoyable and easy.

    These things made way to the progress of mathematics in to a galaxy – to become a galaxy of mathematics. What is your take on this issue and your expertise on the chronology of symbol creations and the advances mathematics made because of this?


    Geng Ouyang · MinNan Normal University

    Dear Dejenie,

    You are right Mr. Dejenie A. Lakew, many people (especially those with physical point of view) argued like that for more than 2500 years. But, it is also true that Zeno’s Paradox of Achilles--Turtle Race is generally accepted as a perfect “defects discloser” within the present traditional finite—infinite theory system with its foundation of “potential infinite” and “actual infinite”. We can forget Zeno’s Paradox, but we can not forget Harmonious Series Paradox-------the “strict mathematical proven” modern version of Zeno’s Paradox of Achilles--Turtle Race.

    Sincerer yours, Geng

  • What is a suitable protocol to analyze Cu2O particles in solution using the UV-Vis spectroscopy (NanoDrop2000 instrument but cuvette measurements)?

    I am trying and study the Fehling's test in solution using the UV-Vis spectroscopy. The test involves the precipitation of red solid particles of Cu2O owing to the redox reaction of a reducing sugar and Cu(II) ions in an alkaline medium. I want to determine the spectroscopic characteristics/differences between free Cu(II) ions and Cu(I) oxide. I have performed some (cuvette) measurements using a NanoDrop 2000/2000c Spectrophotometer but all my spectra are very noisy especially in the UV range (190-380 nm) despite the high absorbance (Amax=2.5) of all my samples. As an example, I cannot even ascertain how many peaks are present due to the noise.

    Does anyone know if the problem could be due to the instrument (high scan speed, just 3 seconds per analysis) or if there is any mistake in my operating procedure?

    Bojidarka B. Ivanova · Technische Universität Dortmund

    Mrs/Miss Zaccaron,

    The standard electrode potentials for pairs Au0/Au+, Au0/Au3+, Cu0/Cu+, Cu0/Cu2+ and Cu+/Cu2+ (Eo [V]) and pK (The shown below E0 and pK values are from ref. [1], attachment):

    Au0 (red. agent) = Au+ (ox. agent) Eo = 1.46 V, pK = 24.8
    Au0 (red. agent) = Au3+ (ox. agent) Eo = 1.42 V, pK = 72.0

    Cu0 (red. agent) = Cu+ (ox. agent) Eo = 0.522 V, pK = 8.82
    Cu0 (red. agent) = Cu2+ (ox. agent) Eo = 0.3460 V,pK = 11.69
    Cu+ (red. agent) = Cu2+ (ox. agent) Eo = 0.170 V, pK = 2.87

    By Nernst's equation (attachment, Eq. (1)) we have obtained highest pK value for the Au-based pairs (pK(Au0/Au3+) = (72.0)) as well as Eo(Au0/Au+) almost equal to Eo(Au0/Au3+). Thus, we can expect that applying a potential difference, nevertheless given starting salt contains Au+ or Au3+ ions we should obtain Au0 in both the cases. Preferrably however is to use Au3+ containing one. For this reason in the previous posting there has been shown as a starting Au3+ salt, namely HAuCl4.

    By contrast, pair Cu+/Cu2+ has lowest Eo within the frame of Cu-based pairs and a pK = 2.87, meaning that applying E we can easy obtain Cu+ product from a starting Cu2+ salt. To obtain from a Cu2+ salt Cu0 we needs a higher potential diference. If we have Cu+, than to obtain a Cu0 product even it is needed additional potential difference within the frame of the studied series Cu-based pairs.

    This analysis assumes, that if you have a Cu2+ salt, for example CuCl2 or CuSO4, you should preferrably obtain Cu2+/Cu+ or Cu+ products depending on the experimental conditions. Usually, Au0-nanoparticles are produced by Au3+ salt, preliminary dissolved in H2O (or CH3OH) under stirring and heating (T = 100oC), adding: 1) NaOH and 2) the shown acid.

    You could try to repeat these conditions using a starting Cu2+ salt. Most probaly you should obtain Cu2O in a high amount in the presence of H3BO3. But please bear in mind that you can obtain mixture of Cu2O/CuO nanoparticles even Cu2O/CuO/Cu compositions, because of pK (Cu0/Cu2+) = 11.69 and this is the higest value within the frame of the series.

    You can evaluate the potential difference of any redox reactions depending on agents by Eq. (2) (attachment) and than to conclude about probability to obtain only Cu+; Cu+/Cu2+ or Cu+/Cu2+/Cu0 containing nanoparticles.

  • Will polymer-polymer film can be measured by Sum Frequency Generation Vibration Spectroscopy for identifies surface interfaces and analysis?

    As I know from the literature this method was used for gas-liquid or liquid-solid interfaces. Even any one gives the idea where (in Indian institute) I will measures my samples ? If outside from India than please provide the details whom I approach ?  

  • Naveed Akhtar added an answer in Reagents:
    What about pyrogalol reagent ?any research about this reagent?

    determination of metals using pyrogalol reagent(C6H3(OH)3)

    Naveed Akhtar · Beijing University of Aeronautics and Astronautics (Beihang University)

    check out these references










    best regards

  • How can I create two groups with an identical mean value and SD?

    I'm looking for suggestions as to how to create two groups with an identical mean value and distribution on the measured variable. Currently, I have two groups with different mean values, distributions and Ns. I have some ideas on how to do this (e.g. working from the mean value of group A, match all group B cases within 2 SDs, then use a random number generator to select a matching proportion of group B within each SD, which should create the same mean value) but I would love some (better) ideas and examples, especially that would work in SPSS. 

    For example, could I specify a normal distribution within group A, then find some way to match this to group B, so that the mean values are the same?

    Thanks for your input!

    Hosam Al-Samarraie · University of Science Malaysia


    Well, you just simply need to insert group A and B values in SPSS, then select the related columns from each group for descriptive measure.

    I would suggest you to perform cluster analysis on each group in order to find possible patterns, these patterns can be associated to a definite membership that can be used in order to characterize these patterns. By doing so, you can provide a new knowledge and increase the strength of your research.