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  • Alain Celzard added an answer in Conductivity:
    In electrical properties, how could you determine the AC conductivity to DC conductivity using Power law and the term Aωs ?

    Can you kindly explain the Power law σ ac = σ dc + Aωs ? How could you determine the terms like dc conductivity and  the term Aws? Is there any other method to calculate the ac conductivity and dc conductivity?

    Alain Celzard · University of Lorraine

    Just plot the log of ac conductivity as a function of log frequency, over a very broad range of frequencies. You'll get a plateau (thus corresponding to the log of dc conductivity, which is therefore determined), followed by a straight line of slope s. All can thus be determined doing this kind of plot. If you see only the plateau or only the slopy line, it means that the range of frequencies is not broad enough.


  • Does new knowledge important to innovate?

    Yes , without new knowledge, we cant drive innovation process.

  • Do photons have mass?
    Photons are traditionally said to be massless. This is a figure of speech that physicists use to describe something about how a photon's particle-like properties are described by the language of special relativity.
    Charles Francis · Jesus College, Cambridge

    Stefano, Einstein's equation seems pretty clear, photons must make a contribution to curvature, which means to gravitation. Otherwise, rather greater paradoxes would be caused through violation of energy-momentum conservation, and the whole empirically verified theory of Big Bang Nucleosynthesis in a radiation dominated universe would fail.

  • Does actinomycin D act differently on different mRNAs from the same cell sample?
    I am working on looking at mRNA stability of two mRNAs from the same cell sample. While one is showing faster degradation with an increase in time, the other one is showing an increase in mRNA level for first few hours and then degradation.

    I was wondering, even if the other mRNA is more stable, how is its expression becoming more increased (almost double as compared to 0 hour) after actinomycin D addition?
    William Perry Lafuse · The Ohio State University

    One possible explanation is that the actinomycin D is not completely stopping transcription of the gene and the gene that shows an increase is more highly expressed or more highly induced if you stimulated the cells first.  I would try increasing the concentration of actinomycin D. However, if the gene is highly stable, e.g. half-life at 6-12 hr or higher, culturing cells for longer than 6 hrs in  high concentrations of  actinomycin may cause cell death.   

  • Divaker Choubey added an answer in Cell Passage:
    Can anyone comment on the stability of CMV promoter driven expression in human cells?

    Glybera (alipogene tipovarvec) is the first human gene therapy which received market approval. According to the distributor Glybera should be given only once in a lifetime.
    The LPL expression is driven by the CMV promotor. Can anybody comment on the long term stability of CMV driven expression in human cells? From my own experiments with stable HepG2 and HEK293 cell lines I know that after several cell passages the expression is going down, gene silencing/deletions or whatsoever.

    Divaker Choubey · University of Cincinnati

    I agree with the response above and would like to add that the CMV promoter allows strong expression in transfected cells. Therefore, if ectopic expression of a gene results in growth disadvantage, cells that express cells are selected with time. Therefore, multiple factors may contribute to the time-dependent reduced expression of transfected gene.

  • Denise Morel added an answer in Cultural Politics:
    Will you say that Communicative Approach Did or Did Not achieve the best in teaching second language?

    After three or four decades of its presences in the language teaching, Communicative approach reached far expectations by its advocates, however recently it sought to be impractical to support the need of learners to overcome their language development. When I first know communicative approach it was the best tools to apply language use in classroom, but soon I discovered it can't be applied for some economical, cultural, and political reasons. If you are teaching a second language and have been using communicative approach for some period of time, what is your reflection on this method? Does it ensure the use of language as proposed by theoreticians ? Why you think or not it can be applied ? think of the reasons that might put this method on the bookshelves rather being taught to students.  

    There are many issues that must be addressed in attempting to answer this question. One is, does everyone who claims to be using the approach in fact really understand the underlying principles and are they using it appropriately? Some teachers tend to equate the communicative approach with certain types of classroom organization – typically pair work or small group work. Others tend to associate it with certain types of activities, such as role-plays. However, just because a teacher uses a role-play in the classroom is no guarantee she is using the “communicative approach”: not if she has the students write out the dialogue first and then practice it out loud several time before “performing” it! The common denominator for any lesson, activity, method or technique to be considered “communicative” is that there must be a true exchange of meaning among the participants. (If, for example, I ask my partner a question that I already know the answer to, I am not asking a real question and there is no real exchange of meaning.)

    When the communicative approach was first introduced, it was against the backdrop of the audiolingual approach, an approach that had dominated language teaching since the Second Word War. It was based on memorization and rote practice, in which learners started with the simplest grammatical structures and then gradually built them up into increasingly complex structures. Although students trained in this approach performed quite accurately on structured tests such as multiple choice and fill-in-the-blank items, they did very poorly in everyday communicative situations (they were unable to “transfer” their “school knowledge” to real life). The communicative approach succeeded in overcoming these limitations by insisting that language is essentially a tool for the communication of meaning, and that form (grammar) is at the service of meaning.

    Unfortunately, once again, what proponents of the communicative approach advocated and how it got interpreted were two different things. Proponents advocated the teaching of form (grammar) in context (e.g. if you are going to teach the verb “to be”, teach it in the context of introducing yourself to someone, or introducing a third person to someone else; and so on). Unfortunately, some teachers misunderstood what the communicative approach was all about and thought that it prohibited the teaching of grammar altogether, which was certainly not the case! So we ended up with students who had absolutely no idea of how the language worked as a system. But we can’t blame the approach for that; it is simply the result of poor training and misunderstanding.

    So before we throw out the baby with the bathwater, we need to make sure what it is we are discarding and why.

  • Navneet Vasistha added an answer in Neuroscience:
    Are there labs in Lyon, France, working on neuroscience & epigenetics?

    I will be visiting Lyon in October and is interested to visit some labs there that preferably work in the behavioural neuroscience/neuro genetics/microbiome/transciptomics/epigenetics fields. Just want to chat, see the labs, and perhaps chat about potential collaborations. Please let me know if you know of anyone there I can contact.

    Navneet Vasistha · The University of Edinburgh

    In addition to Henry Kennedy, you might also want to talk to Colette Dehay who has worked with Prof. Kennedy for many years and has her own lab.

    She was my PhD examiner and a reputed investigator in the field. She works on progenitors in the developing primate brain.



  • Ling xu asked a question in Information:
    Half lives of N-nitrosamines?

    Where could I can find the information about the half lives of N-nitrosamines? Any could provide a clue?

  • Divaker Choubey added an answer in Oral Cancer:
    What way i justified p53 as a specific gene for oral cancer?

    can anyone tell the the specific gene for oral cancer? in most of the oral cancerous conditions P53 were expressed. if i consider this gene as a specific gene means how can i justified?

    Divaker Choubey · University of Cincinnati

    In most human cancers, either p53 itself or the p53 pathway is functionally inactivated. Therefore, if in oral cancers "p53 were expressed", it is conceivable that the protein was stabilized. Consequently, it may be of interest to follow further.

  • Navneet Vasistha added an answer in N2a:
    What are effective inhibitors of methylation for use in cell culture.

    I am selecting for stable transformants in an N2a cell line.  The construct looks like this:  EF1a-gene of interest-IRES-eGFP...SV40-EM7-blasticidin resistance.  I seem to be getting good selection, however the GFP signal seems to be diminishing over time and many of the cells seem to have lost it altogether despite growing well in blasticidin.  Of course this is just by eye, but the signals are very reduced since first they were transfected.  I am concerned about transcriptional suppression and would like to test this by using an inhibitor of some kind.  Would HDAC inhibitors be useful?  Should I use a different promoter perhaps?  Other suggestions for selection?

    Navneet Vasistha · The University of Edinburgh

    Hi Michael,

    You could try using a separate plasmid containing a different fluorophore and see if the fluorescence of the second plasmid also decreases. It could be a case of transcriptional repression but also could be a dilution of your plasmid with successive cell-divisions. Episomal plasmids tend to be lost over time.

    You could try using a bi-cistronic plasmid to check for the transcriptional repression aspect. For the episomal problem, you could clone your gene into a piggybac plasmid and use transposase to insert it into the genome of N2a. It might be more stable that way.

    I would direct you to a paper we published using the piggybac system and got excellent labelling. Garcia-Moreno et al., 2014
    We would be happy to send you the piggybac plasmid alongwith the transposase if you need.

  • In your research paper, what information would you present as tables and what information would you describe in your text?

    In your research paper, what information would you present as tables and what information would you describe?  SPSS gives us a lot of data: Reliability and variances, Means and SD's, normality tests, Levene's tests and t-tests and Pearson Correlation Table are some of the usual stuff.  We also need to bear in mind that the journal may only give us 15 pages or 20 pages, and 1 table has to be on a separate page.  What is your view, how would you present your data?

    Paulinus Woka Ihuah · Rivers State University of Science and Technology and University of Salford, UK

    Fine, but how do you convey to someone outside your belief what your research is all about and they contributions to the body of knowledge without using words fashioned out by you to suit the situation you're solving. It is impossible to use table all through from the beginning of your analysis and results interpretation to the conclusion. If you believe in explanation as the best style, you can only explain you table based on what you interpret the findings of your table to mean in the paper context, otherwise that table is significantly unreliable and cannot be accepted by the audience.

  • What are the current challenges associated with droplet based microfluidics systems for single cell analysis?

    Using droplet-based microfluidics has been investigated for different biological assays with different mechanism for cell encapsulation and sorting. Also, several detection process have been introduced. By the way, what are the new challenges in these systems? What do you think of a cutting-edge research with this topic. Any new ideas are well appreciated. Thanks.  

  • Adam B Shapiro added an answer in Dialysis:
    Protein precipitation on dialysis

    Hi all

    I am trying to isolate a seed protein.I did ammonium sulphate precipitation followed by dialysis against MilliQ to remove the salts.After dialysis the protein is getting too much precipitated.Even after more than 8 times dilution,I am unable to get a clear solution.I have to load this on Sephadex G 100 for SEC.How do I proceed??


    Adam B Shapiro · AstraZeneca

    I don't have any personal experience purifying proteins from seeds, but I wonder whether the precipitated material you are seeing may be starch. If so, or if it is protein other than the protein you are trying to purify, remove the precipitate by centrifugation before the chromatography step.

    If the protein you want is in the precipitate, you may be able to reduce the amount of precipitation by buffering at a different pH and/or maintaining the protein at a different salt concentration. Alternatively, collect the precipitate by centrifugation and try to get it to dissolve in low or high salt, low or high pH.

  • Srijan Sharma asked a question in Import:
    Important advantages

    Important advantages of rack and pinion arrangement over four bar linkage arrangement ?

  • Vilemar Magalhaes added an answer in Logic:
    What logically follows from theory of evolution?

    what is the logical conclusion that follows from theory of evolution?

    Vilemar Magalhaes · Independent

    Arnab, why not trying to change your question? We want to interct with you, learn from you too.  And as you saw above, there is a need to be more specific on that. I will try to be the first to share my point of view.

  • Sherif Edris added an answer in Micronucleus Tests:
    How do you prepare a micronuclei test with gimsa stain?
    I'm preparing a micronucleus slide but I see my slide is very dirty. I'm using normal lymphocyte with carnoy fixative and I'm drying it in slide with air and 10% gimsa stain. How do you prepare good and clear micronucleus slides with high quality?
    Sherif Edris · King Abdulaziz University


  • Maroc Fatma added an answer in Arabic:
    Hopelessness scale arabic version

    I need to hopelessness scale arabic version. Can you help me ?

    Maroc Fatma · Université Kasdi Merbah Ouargla

    it's beck hopelessness questionnaire ( مقياس بيك لليأس) 

  • William Perry Lafuse added an answer in Bone Marrow:
    Protein and mRNA isolation from bone marrow

    Do anyone please help me to get the manual protocol for isolating mRNA and protein from the bone marrow of mice, rat and human? Actually I dont want to use any isolating kit.

    William Perry Lafuse · The Ohio State University

    To isolate bone marrow cells from  the mouse , isolate the femur bones and place in a tissue culture plate. Trim the muscle  from the bones and remove from the knee cap. Clip both ends of the bone, and flush the cells out into a 50 ml centrifuge tube using 10 mls of media in a syringe with 26 gauge needle . Centrifuge the cells. To isolate RNA from the pelleted cells, I would recommend lysing the cells in Trizol and follow the manufacturers protocol to purify the RNA.   

  • What is the best and the quickest method to remove impurities?
    I have screened some compounds using column chromatography and found some minor impurities in the compounds screened.

    Hi Bilal

    You might be interested in the site, please check out

    Best regards

  • Yacine Derradji added an answer in DMSO:
    Which drug solvent is the safest and most non-interfering for anti-inflammatory studies?
    I have problem with the drug solvent in my work on anti-inflammatory effects of plants extracts on carragenane induced oedema (acute inflammation) and collagen induced arthritis (chronic one). Actually I am treating animals orally with a suspension of the oily extract (and indomethacin as control) in gum acacia (2% in water). But I have concerns about intestinal absorption (I need your opinion here).
    The next step is to compare the amelioration obtained by the extract treatment with its individual components, some of these are in crystalline form (ex: thymoquinone: 1mm crystals) and homogeneous suspension could not be obtained. They must be dissolved to unsure the adequate dose administration to animals. Which solvent is the safest (chronic treatment), non-interfering (neither pro nor anti-inflammatory) and what are the adequate doses: DMSO, ethanol….?
    Yacine Derradji · Université de Biskra

    thank you Shanmugapriya Ekambaram for the answer.
    the actives are lipids and i think that suspension do not allow the equal distribution of the drug to the animals in the groupe despite of vigorous shaking of the suspension before administration. dissolving the drug is the best way, but the DMSO is documented to have anti-inflammatory properties which could modify the results. is the ethanol the best choice ?

  • Adam B Shapiro added an answer in Leaf:
    How to extract active proteins from leaf tissue?

    Does anyone know a good protocol to extract active proteins from leaf tissues? I want to perform activity tests on the extracted proteins, so their preservation of activity is very important.

    I found some very basic protocols, including the use of just one buffer (e.g. Tris-HCl), a mortar and pestle and a centrifugation step. Is this the usual way to go?

    Adam B Shapiro · AstraZeneca

    With spinach leaves, we used to use a buffer containing sucrose and a Waring blender to grind up the leaves in order to isolate chloroplast thylakoid membranes.

  • Navneet Vasistha added an answer in Drosophila:
    How to identify Drosophila Mutant...?

    I am searching literature about Drosophila mutant identification. can anyone suggest me books or papers related to Drosophila mutant identification and their maintenance...?

    I also need previous published work on mutant identification related to learning in Drosophila.

    Navneet Vasistha · The University of Edinburgh

    Hi Manish,

    You would be best off reading some of the classical papers of EB Lewis, Weischaus, Nusslein-Volhard and Waddington.
    There is also this good introduction to fly genetics which you should read: http://www.cshlpress.com/default.tpl?cart=141132825824595004&fromlink=T&linkaction=full&linksortby=oop_title&--eqSKUdatarq=469

    Mutant identification is based on genetic screens to analyse specific phenotypes of a particular developmental organ or time. You will hence need to know first and foremost how genetic screens are conducted to identify different mutations (dominant, recessive, sex-linked etc.). Secondly you should read up on the balancer chromosomes used in fly genetics.

    All of this will be contained in exhaustive literature spanning decades of research but if you start from the historic papers, you'd be in good hands.


  • Mahfuz Judeh added an answer in Free Software:
    What is the implication of free software to your research? What is the frequency of R being used, compared to SPSS?

    Today, Saturday, September 20th, is software freedom day.  What is the implication of free software to your research? How can we overcome the difficulty of using freeware, so that our research is able to progress? What, do you think, is the frequency of freeware like R or PSPP being used as compared to SPSS?  Do you have research papers (softcopies) using freeware like R to share here with us?  https://www.gnu.org/philosophy/free-sw.html

    Mahfuz Judeh · Applied Science Private University

    Dear Miranda,

    I think most statistical data analysis can be done on Excel ToolPak. The Analysis Toolpak is an Excel add-in program that is available when you install Microsoft Office or Excel. 

  • What are the various terms being used to express Phosphorus in swine Nutrition?

    Which terms are used to express the availability of phosphorus in Swine Nutrition. 

    Is there a difference between hydrolysable, available and digestible Phosphorus?

    Martha Aku Boakye · University of Bonn

    Dear Jorge,

    you may check this out


  • Alberto Cereser asked a question in Machine Learning:
    Blobs dection and machine learning

    Hi, I have a large stack of images showing a bar with some dark blobs, whose position changes with time (see Figure, b). To detect the blobs I am now using an intensity threshold (c in Figure, where all intensity values below the threshold are set to 1) and then I search for blobs in the binary image using bwlabel in Matlab (more code at the link). As you see the binary image is quite noisy, complicating the blobs detection process. Do you have any suggestion on how to improve the shape detection, maybe using some machine learning algorithm? Thanks!

  • How to show multiple attributes in one legend in ArcGIS?
    I have seismicity data and want to show the depth of events by gradual colors and want to show the magnitude as the gradual size in one legend. Any ideas are appreciated.
    Jose Jimenez · Government of Spain

    Another easy way: add the same duplicate layer, and you can choose the differents legends you want on them

  • What is your opinion on the relationship between community empowerment and re-appropriation of spaces?

    I've developed a methodology that emphasizes on community empowerment and how communities can successfully re-appropriate a space (gain ownership, build identities, enhance contributory and participative cultures etc) but at the same time, bridge the gap between them and authority; creating balance and trusting relationships, strong bonds and a sense of teamwork (this is based on the topic from my last question). The idea is to create a service structure that communities can easily understand and follow, and authority will feel comfortable and confident with.

    My question is, do you think that initiatives like this could be authorized and accepted by communities and authorities? What experiences have you had regarding this topic, and what are your opinions about it? 

    I've attached my most recent presentation for all to see and comment! Feedback would be greatly appreciated!

    John Foster-Bey · CSR, Incorporated

    Glenn you make a good point. I agree that empowerment is both process and outcome. However, what is the metric used to evaluate overall success? One concern I have and I have seen this in operation, is that when an empowerment process fails to achieve a desired outcome, the tendency is to switch horses and talk about the wonderful process. Process matters. How you  achieve your ends is as important as what you achieve. However, process matters because you want to achieve a specific set of outcomes. Process is not goal free. Indeed different goals require different processes.

  • William Perry Lafuse added an answer in mRNA:
    How can I Express "Relative Expression of mRNA" if I have Treshold Cicle?

    Please, I need help because I Have got a normalizer expression (GADPH) of a gene ASC but I need "Relative expression" and I don´t know how can I do.

    William Perry Lafuse · The Ohio State University

    Relative expression  refers to fold changes in mRNA expression between two conditions, for example unstimulated cells vs activated cells. To calculate fold change  from real-time PCR data, you first  subtract the CT value of the normalizer gene for each set of data, to get the delta CT value for each condition. Then, subtract the delta CT value of the unstimulated cells from the activated cells. This number is referred to as the delta delta CT value (ddCT). Fold change is 2-ddCT . Thus, if the ddCT  is -1, then the relative expression of the stimulated cells is 2 times the unstimulated cells.

  • Majid Talebi added an answer in Conductivity:
    Can anyone help with Thin film conductivity measurements?

    I am working on thin films. I want to measure thin film conductivity. I have some result about thin film resistance in (Ohm/square) Unit, which collected by Four Point (Jundel rm3-ar) analyzer, and i don't know how to convert this figures to (Siemens/Meter) Unit. 

    Majid Talebi · Iran University of Science and Technology

    tank you manrico

    your answer is helpful for me,

    i used SEM cross-section for thickness calculation. its about (7-10) micrometer.


  • Nina Sajna added an answer in Cities:
    Have you seen Iron Sticks on the Road in your Area(20cmLength, 0,5cmWidth, 0,01cmThickness)?

    I'll enclose the Picture of the Sample of Iron Sticks apparently 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 you live, or which you haves visited? Many Thanks in Advance for your Comments. Solarity and Happiness inside/outside to Every1.

    Nina Sajna · University of Maribor

    Dear Francesca,

    there is steel and there is stainless steel. Steel, an iron alloy, is known for rusting (btw rust is not poisonous).

    I truthfully thought your reason for asking this question was boosting our imagination like Andras wrote. Since I believe this is not the case, I should finish my contributions here by quoting Charles Darwin:

    "Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science."