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  • Is there a relation between stability and the steady state in a control system?

    are there relation between stability and steady state in control system?

    Zigang Pan · N/A

    Stability is for an equilibrium or a particular trajectory.  It means that if the system starts close to the equilibrium or trajectory, then it will stay close to the equilibrium or trajectory.  Steady state refer to a particular trajectory or class of trajectories that has certain persistence property.  This is a loosely defined term that is in contrast to transient behavior.  

  • John C Grant added an answer in Soil:
    Are there any longer term soil monitoring projects?
    Does anyone know of a project that has tracked the following characteristics at a site in Australia over at least a year on a regular (weekly or daily) basis.

    - Soil Electrical Conductivity (soil resistivity)
    - Soil heat capacity (either volumetric or specific heat capacity)
    - Thermal conductivity / Thermal Resistivity
    John C Grant · Southern Cross University

    Thanks Pei

  • Xuran Zuo asked a question in Caving:
    How can we have rectangular-shape aeolian erosion?

    I observed rectangular-shape aeolian erosion in the coastal area of South China, as shown in the attached picture, very regular pattern and spectacular. We know this kind of caves/holes are usually caused by wind or water force during the erosion. But how can we have such a neat distribution of rectangular holes? Does it mean that during the erosion, the wind was always blowing from one direction that is perpendicular to the outcrop?

  • Can you highiy recommend an excellent tooth vitality tester/electric pulp tester to me?

    I am doing a research about caries, I need to know the status of precise puip vitality , so can you highly recommend an electric pulp tester to me?

    Bernardino Isaac Cerda-Cristerna · Universidad Autónoma de San Luis Potosí

    Dear Isabella, 

    First, you should remember that an EPT doesn't measure "pulp vitality", the EPT detects if the tooth will give a response to an electrical stimulus. Thus it doesn't mean vitality, it means "sensibility" to an electrical stimulus. There's no way to measure pulp vitality with an EPT.  To measure vitality, you should use some sophisticated techniques such as laser doppler flowmetry or pulse oximetry; these systems can measure blood flow and levels of oxygen, signs related to tooth vitality. Indeed, these systems have been considered as the "gold standard" for pulpal diagnosis. 

    Also, you should consider, based on a scientific rational, what is the best diagnostic tests for your objetive. Remember, the accuracy of a diagnosis test is based on "sensitivity", "specificity", "positive predictive value", "negative predictive value", etc. 

    I suggest first to revise the actual concepts of pulpal diagnosis and then to revise the bases of the pulpal diagnosis techniques (What do they measure? How?). After that you can choice the best test to solve your research problem. Maybe an EPT or "cold spray" (1, 1, 1, 2-tetrafluoroethane) are suitable for your objetive, but then you should re-consider to measure "sensibility" but not "vitality". 

    I suggest to read these articles: 

    "Identify and Define All Diagnostic Terms for Pulpal Health and Disease States" http://www.jendodon.com/article/S0099-2399(09)00793-6/abstract

    "Review of pulp sensibility tests. Part I: general information and thermal tests"


    Best regards.

    Can you highiy recommend an excellent tooth vitality tester/electric pulp tester to me?. Available from: https://www.researchgate.net/post/Can_you_highiy_recommend_an_excellent_tooth_vitality_tester_electric_pulp_tester_to_me [accessed May 3, 2015].

  • Louis Brassard added an answer in Consciousness:
    Can consciousness be defined?
    Dan Dennett tries to shake our confidence that we ever can know what consciousness is. Would you agree with him?

    '' Look, if I said to you here is a dollar bill, let’s look at it and try to discover its value you’d say that’s crazy because the value isn’t in the dollar bill. Where is it? That’s an interesting question. And then if you came to me and said "Look, I've got the best electron microscope in the world, let’s really study that dollar and try to find its value." No, you’re looking for the value in the wrong place. And the idea I have is that the neuroscience of consciousness has been making that kind of mistake in assumption about where to look for an understanding of what consciousness is and how it happens, how it arises.'' Alva Noe


  • Khalid El BAIRI asked a question in Lymphangiogenesis:
    What is the best model to study cancer lymphangiogenesis in rats ?

    Im starting the research in the field so im waiting your advices .

  • How are antibodies linked to gold nanoparticles?

    Antibodies are crucial to target cancer cells, how they are attached on gold nanoparticles??

    Khalid El BAIRI · Independent research team in cancer biology and bioactive compounds / Mohamed first University

    a good paper answering your question : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3473940/

  • How can I isolate topoisomerase 1 enzyme from plasmodium cell? Is there any define protocol, please suggest?

    isolation of topoisomerse 1 from plasmodium?

  • Which type of model would you suggest for corporate governance research?

    Most constructs in governance research are unobservable, raising questions regarding the suitability of proxy indicators.  Additionally, the pattern of relationships among variables is often complex, requiring sophisticated designs ranging from mediation to multiplex networks, among others.  Thus, it is not surprising that it is often difficult to identify causal effects in corporate governance research.

    According to these issues and based on your research experience, which type of model would you suggest to handle any such methodological issues?

    Your comments, replies, and justifications are welcome.

    Paul Louangrath · Bangkok University

    MODEL: There are three main approaches to modeling corporate governnance: (i) European, see attached, (ii) US, see Sarbane-Oxley Act, 2002, and (iii) India, see SEBI Report. These three approaches to corporate governance looks to the issues from different perspective. Depending on which approach you take to the issue of corporate governance, the proposed model may not be the same.

    FACTORS: Despite whichever approach you make take to corporate governance, some common factors for the model includes: 

    (i) Rights and equitable treatment of shareholders

    (ii) Interests of other stakeholders

    (iii) Role and responsibilities of the board

    (iv) Integrity and ethical behavior

    (v) Disclosure and transparency

    You could use these factors for the measurement in your survey & modeling. See OECD, Article II, III, IV, VI and VI. Attached file.

  • Adam B Shapiro added an answer in Peptides:
    How can I label my peptide with a fluorescent dye, without conjugation via the amine groups of the peptide, but by linking to the carboxyl group??

    I have a 27-residue peptide, and its specific function is mostly attributed to the N-terminus. So I wanna leave N-terminous untouched and link a fluorescent dye preferentially to the terminal carboxyl group. Do you know any dye and protocol suitable for this purpose? 

    Adam B Shapiro · AstraZeneca

    Reagents, such as hydrazides, are available for coupling to carboxylic acids, but they are not specific to the C-terminus and will also react with glu and asp side chains. Fluorescent derivatives can be found here:


  • Robert A. Shanks added an answer in Epoxy Resins:
    How can I mix sio2 nano particle in epoxy resin at room temperature?

     what will be the weight calculation for same?

    Robert A. Shanks · RMIT University

    I use a sonicator for dispersing nano-silica in epoxy. I have several homogenisers (stator-rotor high shear dispersers such as Ultraturrax), however the sonicator has proved best for small volumes. As Dr Shettar replied 3-10 %·w/w is a maximum because the silica dispersion forms a gel. Add the curing agent after the dispersion step, otherwise cure is likely to occur during dispersion. 

    A problem is that dispersion, then mixing the curing agent into the extremely viscous suspension, results in entrapped air bubbles. The better the dispersion and mixing, the smaller are the air bubbles. Vacuum cycling can remove air bubbles, however small bubbles are difficult to remove because the silica causes physical gelation at even lower (1 %·w.w) fractions. I use a rotary–centrifugal mixer (Thinky is one brand) with a three cycle program: 1 degas, 2. mix, 3. degas. The process results in efficient dispersion, mixing and bubble-free composites.

  • Amit Raheja added an answer in SAP2000:
    How can I calculate yield displacement?

    I require this for validation purpose, I am using SAP2000 V16 in my project, basically I am analyzing G+2 storey steel structure. I have applied Elcentro time history.

    Amit Raheja · AISSMS-All India Shri Shivaji Memorial Society

    Hi Nguyen, are you suggesting non linear multi plastic link?

  • Stephen A. Fulling added an answer in Gravitation:
    Is the coupling constant between the gravitational scalar field and the curvature of the Einstein equations empirically or theoretically derived?

    cosmologist , HEP

    Stephen A. Fulling · Texas A&M University

    There are two factors 1/6 that tend to appear in this game
    multiplying the Ricci curvature scalar. One is the choice of xi
    that renders a scalar field conformally invariant in
    4-dimensional space-time, which is what we've been discussing
    heretofore. That coefficient is dimension-dependent:

    ------       in space-time dimension d.

    (Note that it goes to 1/4 when d -> infinity, for whatever that's

    The other R/6 is a term that appears in the heat-kernel expansion
    for a generic 2nd-order elliptic (Laplacian- or Hamiltonian-like)
    operator. That 1/6 is independent of dimension. I think that it
    is related to the 1/6 that various authors (going back at least
    to DeWitt in 1957) have come up with in developing path integrals
    (or other approaches to quantum theory) in curved space. Other
    authors, including Dr. Olaussen, get 1/4 instead. I have forgotten

    most of what I knew about this topic, but I collected
    some references, which may be useful, in this paper: Internat. J.
    Mod. Phys. D 5 (1996) 597. I missed Olaussen's, but I shall
    certainly check it out now.

  • Jen i-chen asked a question in ADD:
    How do I prepare input control for coimmunoprecipitation?

    What is the purpose of input? Before I perform coip, I take some sample for input control. But input should be analyzed by PAGE on same gel with sample after coip. During this time period (when coip is performed), how do I treat my input? Should I add it to SDS sample buffer right away? Or add sample buffer to input and coip sample at the same time?

  • Mohammed AbdulWahhab Razooqi asked a question in CdTe:
    Hello everybody, could anyone please tell me how to find the thickness of CdTe By RBS and SIMNRA?

    I try to measure the thickness of CdTe from RBS , i found the solid angle, the no. of particles, but i dont know how to find differential cross section and what i have to do.

  • Hui Huang added an answer in Abaqus:
    Restart analysis in abaqus does not work when i toggle on overlay option?why?

    hi al ,

    i was running an implicit analysis for 2 days and system shut down and the restart analysis option is not working since i toggle on the overlay option showing an err"there is no frame for step-2 increment 37". i read that the reference frame will still remain even if the system shuts down if the overlay option was used.

    so i tried with an example to not use the overlay option and it worked .

    can anyone suggest how to restart my analysis(since i had used the overlay option at the beginning to reduce memory usage)

    Hui Huang · Osaka University

    I mean the analysis during which your system got shut down could have a incomplete record if freq=1, because it was overwritten, but not finish yet. I sugest you check the volume of a complete res.file and the one when system shut down. So it really depends. If this is not a big issue, you can temperarily copy the res.file during your way of analysis and jog down the step no. incr. no. just in case. good luck!

  • Hi, how we can get SiC and Al2O3 articles?

    for composite materials,we generally use SiC or Al2O3 particle, how we can elaborate nano particles of these particles? 

    Marcos Augusto Lima Nobre · São Paulo State University

    Dear Dr. Hayoune:

    There is a Scientific Portal free access called Scielo. I think that is possible to find some papers in these areas.


    Major fraction of periodic use brazilian prortuguese language and spanish language.

    However, there is some Journals in the Materials and Physics that publish in English.

    Also, direct access:


    Kind regards

    Marcos Nobre

  • Paul Louangrath added an answer in Impulse Response:
    How to interpret the coefficient units on vertical axis in Impulse Response Function?

    I have two time series, annually data, for 34 years, units are in Rs. Crores. Data found non-stationary & converted into stationary after taking, log then 1st diff.

    I applied the IMF test & found the coefficient units on vertical axis as: 0.03, 0.02,0.01, 0.00 & -0.01. How can I interpret these coefficients units?  e.g. in %,  in  growth rate or something else. Kindly guide me....... 

    Paul Louangrath · Bangkok University

    VERTICAL axis is the dependent variable Y. You meant to say HORIZONTAL axis or X axis for independent variable (explanatory) ?

    Coefficient mean factor or multiplier. It has no unit, i.e. 0.03X means 0.03 times X. Whatever is X unit of measurement,the product of the multiplication from the coefficient takes the unit of that X. What is the full equation you have? Are these coefficients: 0.03, 0.02, 0.01, 0.00 & -0.01 on the RIGHT HAND SIDE of the equation? If so, they are on horizontal axis, not vertical because the vertical is the Y-axis.

  • Daniel M Cohen added an answer in PAM:
    CRISPR and inactivation of nuclease domains of Cas-9?

    Also, if you inactivated both nuclease domains of Cas-9 it could still be localized to specific genomic locations by the gRNA and pam sequences buy couldn't cut the DNA. Can you imagine any use for this as a research tool? You can further modify the tool if you like but the nuclease domains must remain inactive. Explain at least one biological question could be answered with this new tool and describe how it would be used.

    Daniel M Cohen · University of Pennsylvania

    Nuclease-deficient Cas9 is commonly referred to as "dCas9." As Sahil mentioned, a quick lit search will bring up dozens of citations using it to mark different chromosomal loci for a variety of applications, such as imaging subnuclear compartmentalization/localization of DNA in living cells, or programming activation/inactivation of a gene of interest (using dCas9 coupled to transcriptional activators or repressors).

  • Daryn Dyer added an answer in Questionnaire:
    Does someone know how to evaluate the feasibility of, for example a fasting program by questionnaire?

    I am looking for a questionnaire to evaluate the feasibility of a fasting program after a 12 week intervention. The participants should complete the questionnaire at the last day of the program. 

    Daryn Dyer · York University

    Hello Till,

    These articles surround the topic of nutritional assessments, scales questionnaires and methodologies, perhaps there is enough here to develop your own tool. You might consider Theory of Planned Behaviour (Ajzen, 1991).

    Baecke, J. A., Burema, J., & Frijters, J. E. (1982). A short questionnaire for the measurement of habitual physical activity in epidemiological studies. The American journal of clinical nutrition, 36(5), 936-942.

    Grange, D., Eisler, I., Dare, C., & Hodes, M. (1992). Family criticism and self‐starvation: a study of expressed emotion. Journal of Family Therapy, 14(2), 177-192.

    Katzman, M. A., & Lee, S. (1997). Beyond body image: The integration of feminist and transcultural theories in the understanding of self starvation. International Journal of Eating Disorders, 22(4), 385-394.

    Vellas, B., Guigoz, Y., Garry, P. J., Nourhashemi, F., Bennahum, D., Lauque, S., & Albarede, J. L. (1999). The Mini Nutritional Assessment (MNA) and its use in grading the nutritional state of elderly patients. Nutrition, 15(2), 116-122.

    Williamson, D. A., Martin, C. K., York-Crowe, E., Anton, S. D., Redman, L. M., Han, H., & Ravussin, E. (2007). Measurement of dietary restraint: validity tests of four questionnaires. Appetite, 48(2), 183-192.

    Good luck!

  • Sridhar Vadahanambi added an answer in Battery:
    Is there any commercially available anode material (other than graphite) in Li-ion battery technology...?

    Hi everyone,

    At the moment, Is there any commercially available anode material (other than graphite) in Li-ion battery technology...? which is now using in Li-ion batteries...?

    Sridhar Vadahanambi · Global Core Research Center for Ships and Offshore Plants,

    Not sure but many startups.. see this list:


    Especially, Prof. Yi Cui's silica based anode by his start-up company Amprius.. 

  • Jaesik Yang added an answer in Lactobacilli:
    How can I isolate lactobacilli from sourdough?

    Thanks in advance for your replies.

    Jaesik Yang · Handong Global University

    You can find  the method from some articles, 

    I introduce a paper that you would be interested,

    you can find it at  http://www.ncbi.nlm.nih.gov/pubmed/19146533

    ,fortunately, it is open access

    I hope it would be helpful to you,

  • How can I increase my 260/230 ratio- Qiagen RNeasy Mini Kit?

    Hi everyone, I'm looking to extract high quality RNA from frozen PBMCs (~400,000 - 1 million cells) in order to look at gene expression using qPCR. My RNA yield has been around 100ng/ul and the 260/280 ratio around 1.90. However the 260/230 ratio is very variable from 0.28-1.75 .. I believe this number needs to be >1.85 in order to perform reliable qPCR analysis. Has anyone had this experience and has any tips/protocols/recommendations? As well, I've heard that the RNA yield could be higher ~300ng/ul, do you have any recommendations for increasing the yield?


    Daniel M Cohen · University of Pennsylvania

    RNA yield varies a lot across cell types. Not enough information here to know whether storage of your cells or degradation of the RNA during the purification is negatively impacted your yield. Nonetheless, total yields may be between 1-15 microgram range (https://www.qiagen.com/us/products/catalog/assay-technologies/real-time-pcr-and-rt-pcr-reagents/rneasy-mini-kit/#productdetails). Primary cells tend to be on the low end of this range, so depending on your elution volume, your yield may not be that bad.

    Absorbance at 230 and below often comes from carry-over chaotropic salts in the RLT and RW1 buffers. Make sure the wash with the RPE buffer coats the entirety of the column (including the lip on top). You can always perform a second RPE wash to be certain of salt removal.

    Performing the elution step for 5' in a 70-80C heat block can enhance yields by as much as 50%. Might be worth a try if your yields are limiting for downstream applications. For qPCR, however, it seems that you have plenty of material (cDNA from 0.5 ug of total RNA is usually adequate to perform dozens of PCR reactions).

  • Amirul AB added an answer in Amputation:
    Does anyone know of a functional mobility or balance measure like the DGI or Tinnetti POMA that has been validated for LE amputees?

    I'm familiar with the literature on the BBS and L-test for use with LE amputation. I am looking for a broader measure, reliable and valid for this population, that could assess gait/functional mobility with some challenges to gait that would speak to dynamic balance.  

    Amirul AB · Northumbria University

    Hi Helen,

    Very good question which i can learn from it.

    Maybe this could help,


  • Does anyone know, how to coding the country and annual data in stata and excel sheet?

    i having annual data of different countries and different variables, but i do not know how can  i code them and analysis the data in STATA? 

    Khalid Usman · University of Science and Technology of China

    The question in this paper is about the relationship between patent trend, intensity and research output collaboration. With this purpose, the paper is going to deal with
    empirical research of the number of patents, R&D expenses, GDP growth rate, Patent application resident, R&D expenditure, school enrollment territory ( % gross).

    The  data about ,Documents, Citable documents, Citations,  Self-Citations,  Citations per Document,  H index is 1996-2013 collectively, not  annual data. I want to analyze the relationships on the National and Global Patenting Trend, Intensity and research output collaboration of South Asian countries.

  • Does anyone kindly advise me on how to effectively collect data from public sector?

    I am conducting a qualitative research on Building Information Modeling in Australia. One part of my research is to collect data from public sector regarding their interest on BIM. I am not sure what approach is the most suitable for that. I have taken into account some ways comprising face-to-face interview, phone interview, questionnaire and on-line survey via Survey Monkey but still not been sure yet. Any thought would be highly appreciated. Many thanks for your attention.

  • Bokeum Shin asked a question in Primer:
    I have problem in my LAMP PCR. Can anyone help me?

    Hi I'm working on LAMP PCR and I found LAMP primers for 7 genes.

    each primers are positive for their gene, but sensitivity is only 0.5 ng

    On other publications, LAMP PCR can detect about 0.005ng

    what is the problem? I can't understand.

    I used Bst polymersase and genie 3(Real-time LAMP, I used master mix). sensitivity of both is  0.5 ng.

    I used PAGE purified inner primers. and even if I use loop primers, the result is same.

  • Andrés Pavas added an answer in Harmonic Analysis:
    Starting from what length (and frequency) should we consider distributed line model for power distribution lines?

    As a rule of thumb for transmission lines, we know that short lines (shorter than 80 km) are modeled as series impedance, medium lines (80-250 km) are modeled as PI section, and long lines (>250km) are modeled using distributed line models.

    Now, when we perform harmonic (higher frequency) analysis on distribution network with underground cables (which have large parasitic shunt capacitance), the wavelength dramatically decreases. 

    Is there any study to estimate in what frequency or line length (or in general in what multiplication of the wavelength) we consider distributed model for distribution lines for harmonic analysis? 

    Andrés Pavas · National University of Colombia

    Recently I have been involved in a project where modeling of power line communication devices was required. I asked some experts on communications, they suggested such criterion and seemed to be reasonable, but I have not checked references. However, I would always suggest Paul Clayton's book on modeling multitransmission lines or his book "Introduction to Electromagnetic Compatibility". Probably you will not find such thumb rules anywhere, the best would be to try some simulations and pick the best length partition.

    I hope you find the best solution for your problem.

    Regards, AP

  • Muhammad Khattab added an answer in FTIR-RAMAN:
    Which equipment, laser and filters should be used for Raman spectrum?

    I am going to record the Raman spectrum of my solid compound for the first time. i was asked which equipment you want to use, lasers and filters. So, i appreciate if you could help me to determine these criteria. Theoretically, i got the IR and Raman spectra within 400-4000 nm.

    Muhammad Khattab · National Research Center, Egypt

    Thanks, all!

  • Shyam Nyati added an answer in mRNA:
    Methods to study Homo sapiens RAD51 paralog B?

    Would anyone give me some advice on studying this gene?

    Homo sapiens RAD51 paralog B (RAD51B), transcript variant 2, mRNA. 

    Shyam Nyati · University of Michigan

    If this gene is also involved in DNA repair (homologous recombination and double strand break) than some methods to study would be treating cells in culture with radiation and counting number of foci etc. you could tag this gene with GFP and study its movement with respect to time at the site of DNA damage (time and dose). You could also perform a CO-IP and see what other proteins it interacts in response to DNA damage etc. There are some sensors/reporters which are used to study the DNA damage response, you could use those reporters with the WT and mutant RAD51b.

    Good luck with your planning.