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  • David Cho added an answer in Lyapunov Stability:
    Sliding mode control approaches that do not need the bounds of uncertainties?

    As far as I know, conventional sliding mode control technique requires the upper bounds of uncertainties to prove the Lyapunov stability.

    However, sometimes estimating these bounds is very hard or almost impossible in real-world systems. So I am wondering if there are some SMC approaches that do not require the bounds of uncertainties.

    Thank you very much.

    David Cho


    I have read the 'Adaptive Sliding Mode Control' written by Utkin and Poznyak.

    However, I found that they still use the 'sign' function which may result in chattering even though the gain K is minimized.

    Is there any paper or article that does not use the 'sign' function, but use a continuous function? I am also wondering if there is an article that handles a MIMO (Multi-Input, Multi-Output) system.

    Thank you very much.

  • Mohammad Imangholiloo added an answer in ERDAS Imagine:
    What may be the possible issues arise when converting shapefile to aoi in ERDAS imagine 2014?

    while trying to convert shapefile to aoi, everytime blank aoi is created without any dotted line. I am aware of the simple conversion steps, but in my PC i could not do it successfully. plz help me with your suggestions.  

    Mohammad Imangholiloo

    Dear Nilimesh,

    Even though, you know the steps, I think it is a good idea to have a watch these videos. As this conversion is tricky one!!!



    Hope to be useful,

    Best Regards,

    Mohammad Imangholiloo

  • Douglas Maya asked a question in Transcription:
    Protein stoichometry of multisubunit complexes?

    Does someone know an example (published if possible) in which the overexpression of one of the components of a multisubunit complex leads to a transcriptional downregulation of another one? It should normally work the other way around right?

  • Anil Kumar Chekuri asked a question in Fractionation:
    What are the protein controls for checking the purity of hydrophilic and hydrophobic fractions during membrane fractionation?

    Marker proteins for Hydrophilic and hydrophobic protein fractions 

  • Eduardo I. Faúndez added an answer in Larva:
    Does anybody have a photo or drawing of final larva in these four aeshnid species?

    I'm looking for a photo or drawing of final aeshnid larva of four aeshnid species (Amphiaeschna ampla, Rhionaeschna absoluta, Gomphaeschna antilope, and Triacanthagyna septima) in order to ascertain the relative size of lateral abdominal spines. Can someone help me?

    Eduardo I. Faúndez

    Follow Natalia Von Ellenrieder, she may have something

  • Chinyere Amadi added an answer in Med:
    What should be the appropriate statistical test to conduct if investigating dietary intake and Mediterranean diet intake of a cohort using FFQ?

    I used the EPIC FFQ to collect data on food intake. FETA software was then used for nutrient analysis and food group analysis. I also used the 14 - item med diet short screener to collect data on med diet intake. I am trying to find out if their reported dietary intake is consistent with reported med dietary pattern.

    Chinyere Amadi

    Thanks Laura and Joan. Laura you are correct with your first guess. I am trying to see if the dietary intake reported by the participants in the FFQ is in compliance with what they have captured in the 14 item med diet short screener. Joan, that is my research question. From what you are saying Laura, i should carry out a correlation test on SPSS and also a Chi-square test? however, FETA produce data on both daily nutrient and food group intake when FFQs were analysed, so now which one of the data is appropriate to run test with. I am guessing the food group intake data.

  • Joan Vaccaro added an answer in Primary Care:
    What is the prevalence of Type 2 diabetes in patients with dementia?

    I have not found any published data, on the above question , on research done in a primary care setting.

    Salim Sunderji

    Joan Vaccaro

    Salim, usually the research question is "what is the prevalence of cognitive decline in patients with type 2 diabetes?" Below is a link to an article that provides mechanisms for cognitive decline and diabetes. The confounder to your question is age. Diabetes and cognitive decline are higher in the elderly. At the same time, adults 85 years and older are the fastest growing population. This article also provides a summary of representative prospective epidemiologic studies relating Type 2 diabetes (T2D) with dementia.

  • Eduardo I. Faúndez added an answer in Insects:
    Could someone advise me about a field guide for flies or the contact to get it?

    I am sampling insects in La Malinche, Talxcala, Mexico. One of thous insects are de flies. 

    Eduardo I. Faúndez

    Es dificil que encuentres una referencia mejor que las que te dijeron mas arriba, pero si encuentras algo mas cuentanos por aca!

  • Arno Gorgels added an answer in Foundations of Physics:
    Do you agree with Stephen Hawking's recent conclusion that black holes don't exist?
    Black holes don't exist. I published this many years ago. Cantor's Universe doesn't allow the concept.

    Stephen Hawking now came up with the same conclusion. Read: http://www.spektrum.de/news/es-gibt-keine-schwarzen-loecher/1222059

    In my opinion he is right this time. What is your opinion? Was he right then or is he correct now?
    Arno Gorgels

    One wonders what mass is and how it can occur in high density. Isn't mass a field equation?

  • Megan Yu asked a question in HapMap:
    What are all of the publicly available genetics databases?


    I was wondering, other than The Cancer Genome Atlas and The International HapMap Project, what other public genetics databases are available out there?

    Thank you for answering my question.  

  • Kelvin Anjos asked a question in Homological Algebra:
    How to show that a maximal essential extension E of a submodule S of one injective module I is injective?

    I is an injective module

    S is submodule of I

    E is a maximal essential extension of A

  • Glenn Althor added an answer in Scoring:
    How to apply factor scores to likert scale data

    I am trying to replicate the methods of other papers using FA which describe applying the factor scores to their data.

    I have a 7 point likert scale data set (consists of 28 variables and 302 observations) that I have performed factor analysis on. The factor analysis has given me 5 clear factors which I have named.

    However I cannot find a clear method for using or reporting the factor scores etc. Do I take the mean of the variables that make up each factor and then multiply it by the factor score for each factor, for each observation?

    Glenn Althor

    Thanks kindly for the responses all. 

    James, you have described what I'm doing.  However, I'm still not sure what I can do with my factor scores now that I have them. 

    This is a quote from the paper of the method that I'm trying to emulate: "values were calculated using factor score weights from single sub-scale models that were then applied to individual raw scores and averaged to give a mean for each population sub-scale."

    I think that this implies that they multiplied the weights of each factor by the score (and then took the mean)? I have a table of scores for each observation and a table of weights for each variable, but I'm still unsure how to 'apply' the weights to the scores. 

    I am using R do to my analysis. 

  • Chandrashekara M. asked a question in Cultivation:
    How to detect underground water location point and quantity availability for agriculture purpose ?

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

  • Cyril Mechkov added an answer in Circuits:
    Can we call it a non-inverting summing amplifier?

    Inverting summing amplifiers are well known. However, attached is a circuit with two versions. The first gives an output from the amplifier that is equal to the average value of three input signals. The second gives an output equal to the sum. The topology can be extended to higher inputs, but I cannot recall it being documented in text books on op amps. Can it be called as a non-inverting summing amplifier ?

    Cyril Mechkov

    "Virtual connection"? Yes, I think so. The virtual ground is a special case of this virtual connection when the non-inverting input is fixed... and, as a result of the negative feedback, the inverting input is also fixed...

    Now imagine the non-inverting circuit inputs are at constant voltage... the op-amp non-inverting input will be constant... and the op-amp inverting input will be constant as well. So it will serve as a virtual ground again. Only this will be movable (by the side of the non-inverting inputs) virtual ground.

    So, as before, the non-inverting inputs are "interacting" while the inverting inputs are "non-interacting".

  • Abdalla Garguri added an answer in Business Models:
    The Business Model Canvas: What theory could identify/explain its advantages over other business model approaches?

    The Business Model Canvas is tremendously successful. But what’s bothering me is the question of WHY?

    Obviously, good marketing by Osterwalder & Pigneur is involved (workshops, blogs etc.). However, this can’t be the whole story, right? Not so many people would use the Canvas if it didn’t have any value over competing business model approaches.

    I believe the success cannot arise from the choice of the nine components either. A number of authors have proposed business model components similar to those in the Canvas but did not have comparable success.

    Rather, to me it seems to be about the visualization (visualization = the "grid/matrix" that visually arranges the nine components). But then the question is: How does the visualization make the Canvas good/useful? And which theories could help to shed light on this? Is it possible at all to provide a theoretical explanation?

    What are your ideas concerning these questions? I am looking forward to any hint or suggestion :-)

    Many thanks in advance!!!

    Abdalla Garguri

    The Business Model Canvas is built over many theories or consists with them.

    Each element in the  matrix has a root in one theory or more.For example, Key partnership consists with the following theories, at least it covers the main concept, collaboration, alliance, supply chain, open innovation, and open business model.

    However, each firm has its own conditions that lead to give varying values based on the relative importance for each of nine elements in the matrix.

    As Yujuico said, the contingency theory provides the base for this model.

  • Kenneth M Towe added an answer in Climate Change:
    Are there authentic published work confidently pinpointing the sole anthropogenic factors contributing to Climate Change?

    Combined natural and anthropogenic factors (geologically recent phenomenon) govern Climate Change. It is, therefore, of paramount importance to discretely recognize the role of humans in Climate Change and to plan efficient strategy to mitigate it.

  • Vicko Krampus added an answer in Business:
    How to analyze a business letter?

    Give me an example how to analyze a business letter

    Vicko Krampus

    How to analyze a business letter?

  • Vijay Raghavan added an answer in Turbulence:
    What is the critical reynolds number for turbulent transition of R134a and formulea to calculate Re no for 2 phase flows?

    What is the critical Reynolds number for turbulent transition of R134a and formula to calculate Re no for 2 phase flows?

    Vijay Raghavan

     @Ajeesh, You have oversimplified your question, treating it as if the definitions are similar to that of a single phase flow. You have not said what your system is - Is it boiling or condensation? Is it normal sized channel or a mini- or micro- channel. If you have studied the background literature, you will have noticed that the Martinelli parameter is used in almost all boiling correlations, that different Re numbers are defined such as: Re-liquid only, Re-gas only, Re taking the entire flow as liquid, Re taking the entire flow as gas. The two phase Re no. has been defined in different ways by different authors. For example in the classical model of Chen, Re(2-ph) is taken as Re (liquid alone) X F^1.25. For the expression F, please see Chen's paper.

    Please remember that two-phase predictions have by no means reached a definitive stage. That is perhaps why you are researching it at North Carolina. If you have not done so already, you might begin by looking into the papers of Chen (1963, 1966).

    This will be a soft start  as subsequent models are more complicated.

  • Grant Mitman asked a question in Mosses:
    Does anyone have some suggestions to ammend acidic soil to promote moss proliferation?

    any suggestions of useful gels or other additives or protocols?

  • David Charles Wright-Carr added an answer in Scientific Method:
    What is the cogent purpose in seeking to bridge the natural and social sciences?

    What might be the meaning  in terms of human experience and planning in seeking to bridge the natural and social sciences.  If study of the rationale with scientific method is entailed, what practical value might or might not follow?

    If interested the enclosed link addresses my own perspective in philosophical approach to issues of mind verses matter. 

    David Charles Wright-Carr

    Thank you, Marvin. The article you provide is interesting, both for understanding the origins of life and as a case study of the pitfalls of research.

    Being open to all possible hypotheses until there are compelling reasons to reject one or more of them is one of the features that makes science such a useful framework for understanding our surroundings and ourselves (even in what is called "art history," which many colleagues don't want to consider a "social science," but a branch of the "humanities", thus avoiding the critical rigor of science all together). From my point of view, the basic ground rules of science permit a level field for fruitful interactions and combinations in inter-, multi- and transdisciplinary research.

  • Michael P. Weinstein added an answer in Climate Change:
    Is it time we shift emphasis from technological solutions to climate change & focus on the 'Human Dimension'?

    Isn't the obvious solution and the elephant-in-the-room 'BETTER HUMAN BEINGS'? Shouldn't the focus be on better human beings rather than better technology? Why is it that everyone wants to develop better technology rather than focus on better humanity? Because no one has the answers and no one wants to change themselves? In environmental degradation, is it not obvious that nature can heal itself, if only left alone, and it is we humans who need regulation? Many natural parks managers do just that; seal off the area from human interference to let nature heal and recover. It is classified as 'Strict Nature Reserve"by IUCN. Complacency and inaction are not advocated here, as many have misunderstood, but the shifting of focus from technology to the human being. As technology is no match for human greed, isn't introspection & restraining ourselves more relevant than developing more technology, which caused the mess in the first place, by making it easy for a few to consume more? Since technology is only a short term quick fix which fails after a short time, isn't the real problem our addiction to material consumption & our lack of understanding about human nature? Isn't developing more technology sustaining the addiction instead of correcting it, leading to more complex problems later on, needing more complex technological quick fixes like higher drug dosages, more ground troops & equipment, (along with their debilitating side effects) in the future? Isn't this the vicious addiction circle we are trapped in? As researchers, do we merely buy more time with technology OR go to the very root of the problem, the human being?

    A lot of hue and cry is made about climate change and the environment in general. Public and private money is poured into research to study its effects on the environment, sustainability etc. Should we study nature or ourselves?

    " Our studies must begin with our selves and not with the heavens. "-Ouspensky

    Human activities have been found to have a direct correlation to climate change and its impact on the environment(I=P x A x T, the Ehrlich and Holdren equation), in spite of what some complacent sections say to protect their own self interests.

    We hardly know about Human nature. We can scarcely predict human behavior. We need to find out why we think like we do and why we do what we do and why, in spite of all knowledge and wisdom, consume more than what we need, in the form of addictions to consumption and imbalance not only ourselves but also the family, society and environment around us..
    Humanity is directly responsible for all the unnatural imbalances occurring on the planet. Yet we refuse to take responsibility and instead focus on climate change, or fool the public exchequer with a 'breakthrough in renewable energy just around the corner'. We scarcely know what drives human beings. If we had known, all the imbalances around us would have had solutions by now, given the amount of money plowed into finding such solutions. Are we blindly groping in the dark of climate change because we don't know the answers to our own nature?
    Is it not high time we focus on what makes us human, correct our consumptive behavior and leave nature to take care of climate change? Why focus effort on 'externals' when the problem is 'internal'- 'me'?
    Aren't we addicts denying our addiction and blaming everything else but ourselves?

    " We are what we Think.

    All that we are arises with our thoughts.

    With our thoughts, we make the world." - Buddha 

    IMHO, We don't need to save the World. It is enough if we save ourselves from ourselves. The need of the hour is not vain glorious interventions, but self-restraint and self-correction!

    The Mind is the Final frontier.

    + 2 more attachments

    Michael P. Weinstein

    Ajit; just in jest:

     We think too little and depend on emotions too much;

    More than humanity alone, we'll need scientific curiosity;

    As much as kindness and gentleness, we’ll need intellect to survive!



  • Ilya Tsyrlov added an answer in Tilapia:
    What is the simplified assay method for Cytochrome P450?

    I'm working on the impact of water pollution on the physiological and histopathological responses of Nile tilapia.

    Ilya Tsyrlov

    Hi Afaf,

    As a state-of-the-art paper of my fellow Fred Guengerich and his colleagues concerns exclusively determination of P450s in the rodent and human samples, let me suggest you a protocol related directly to the procedure with P450-containing samples from a fish, – the procedure established in the lab (now Institute) of John Stegeman.

    Fish livers were thawed and homogenized (approximately 1g liver tissue) in for volumes of homogenization buffer (0,08M Na2HPO4; 0.02M KH2PO4; 0.15M KCl, pH 7.4). Homogenate was centrifuged at 10.000 x g for 20 min at 4°C. The supernatant was ultracentrifuged at 100.000 x g for 60 min at 4°C. The pellet was resuspended in 1ml of resuspension buffer (homogenization buffer with 20% glycerol, v/v) to obtain the hepatic microsomal fraction. All the spectroscopic P450 (thereafter – CYP)  analyses were carried out with this fraction. Protein concentration was determined using bovine serum albumin (BSA).

    Analysis of total CYP was based on the methods described by Omura and Sato, using differential visible spectroscopy with some adaptations. This protocol compares an oxidized aliquot of microsomal fraction with another reduced aliquot, which is bubbled with carbon monoxide. Liver perfusion was performed with an isotonic saline solution (0.9%) in order to prevent contamination by hemoglobin. Because fish liver samples of are usually very small, the perfusion was carried out by injecting the isotonic solution into each fragment of tissue until it showed a yellowish color.

    Blood of a fish of interest was collected by cardiac puncture in order to obtain hemoglobin. The hemoglobin was treated exactly as the microsome samples and UV-vis spectra were recorded. Aiming at reducing the influence of hemoglobin on CYP spectra, concentrations of 20 μM of phenasine methosulphate (PMS) and 2 mM sodium ascorbate were tested, which have been suggested to reduce contaminant hemoglobin without reducing CYP. Analysis was carried out in a dual beam differential spectrophotometer.

    Best wishes,


  • Mousa Dahabreh asked a question in ANSYS Workbench:
    How can I run a Mass Optimization in Ansys Workbench?

    Hi all,

    I have created a bridge model that consist of 551 line bodies. My main objective is to reduce the weight/mass having the cross-sections to be variables.

    As my arch ribs are of constant cross-sections, I had to divided them into multiple small lines (122) as to connect them properly for meshing. They however have different mass for each of them now.

    For optimization, I would like them to be considered as one structure. Same goes for my main girders..

    However, if I want to create a parameter for each cross-section, I will end up with 551 design variables (Total bridge line bodies). This also might lead to having different optimized cross-section for individual members that create of what must be 1 consistent arch rib.

    Any suggestions? 

    Any kind of help or guidance is greatly appreciated.

    Thank you in advance!

    Best regards,


  • Alejandro Urzúa added an answer in Linaria:
    What is the best method for alkaloids extraction?

    I used the preliminary phytochemical screening of two Linaria species and I found that the results showed high presence of alkaloids, I already investigate both species but i didn't find alkaloids, so I want to try again to extract only alkaloids, can any one suggest good and easy methods for extracting alkaloids from plants?

    Alejandro Urzúa

    Thamere: the following paper, “A New Pyrroloquinazoline Alkaloid from Linaria vulgaris” may help you.


    Good luck

  • David Raikow added an answer in Water Quality:
    Does anyone require acid-washing of water quality bottles and filtering equipment to be conducted under a hood?

    ...using a 10% acid solution made from 36.5-38% HCl.

    Also, does anyone have a Job Hazard analysis for acid washing water quality bottles and filtering equipment

    David Raikow

    Would doing this outside mitigate the risk of inhaling fumes?

  • Carlos Oscar Rodríguez Leal added an answer in Model Selection:
    How can I refuse some category of questions?

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

    Carlos Oscar Rodríguez Leal

    In the section "Your skills and expertise", do click in edit and then click in the cross of the areas to refuse. After do it, give click in the cross of the areas to add, in "Suggested skills", or write in the box the respective skills.

  • Guilherme Maia Santos asked a question in Relaxor Ferroelectrics:
    What exactly means relaxation time in Relaxor Ferroelectrics?

    The relaxation time in Relaxor Ferroelectric are related with the time that the nano regions get back to the standart state before the electric field applied?
    And this is one of the reason that appear a broad peak in the dielectric constant as a function of temperature?


  • Dilara Atav asked a question in Child Abuse:
    Does child abuse cause crime ?

    Does child abuse cause crime ?