Q&A

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  • Why is anaerobic digestion not used for low strength wastewater?

    anaerobic treatment is usually done for high strength wastewater but not low strength wastewater. Why?

    Juan Antonio Baeza · Autonomous University of Barcelona

    Yes, methanogenesis is produced at very low substrate concentration, but the rate will be very low and then you will need a very long residence time.

  • Ghazi Al-Assaf added an answer in Economic Growth:
    What is the impact of remittances, especially on developing economies?
    Does the money sent abroad really have impact on the economy of the country it is sent to?
    Ghazi Al-Assaf · University of Jordan

    There are a lot of research items that have been done over the last decades, addressing the question whether workers’ remittances have macroeconomic and financial effects on the country of origin. Most of this work has been directed to the impact of remittances on economic activity level, as well as poverty reduction. Most of them found that remittances affect the economic variables positively.

  • Peter T Breuer added an answer in Particle Physics:
    Is bias by omission the new accepted standard for scientific discoveries since it was awarded a Nobel Prize?

    When the initial announcement was made by CERN that the Higgs boson was discovered, I inquired as to which origin variable of selection caused the collision effect used to validated this discovery. I was surprised to find out that the discovery was biased by the omission of the variables necessary to obtain particle collision effects in the first place (see peer-reviewed manuscript link below).

    In order for the omission error to be irrelevant to the validity of the Higgs boson discovery, the effect of particle collisions would need to take place without the particle beams intersecting. Recently, CERN physicist, Adam Jacholkowski, confirmed that without the particle beams intersecting that, "In all these cases we do not see any event of interest from the physics point of view that is we do not observe any kind of collisions."

    With the confirmation of my findings that the Higgs boson discovery is based on an omission error, I am compelled to ask, is bias by omission the new accepted standard for scientific discoveries since it was awarded a Nobel Prize?

    If so, then why bother with the pretense of conducting experiments at all since such bias can only lead back to conjecture, not to the advancement of knowledge?

    Peter T Breuer · Birmingham City University

    "In other words, when the origin variables of selection come to exist, energy exists, for they are one and the same. " 

    Sentence not grammatical. It no sense make.

    You fail to write sentences that can be understood by people, computers or nature. That's a killer defect. First learn to write.

    What is an "origin variable". What is a "variable of selection"? Are you perhaps confusing "variable" and "parameter"? What on Earth does the word "origin" do in that sentence except stop the reader dead in his/her tracks? What is the "they"? Selection + energy? Or variables + energy?

    For Goodness' sake, write grammatically, please! Or people will say you are off your meds, and I have my suspicions too. 

    I'm doing my best to get something coherent out of you, and just not getting a response. The sentence above means nothing! If that's the denouement for the thought experiment story, the story conveys nothing.

    "I found that we have the ability to choose because we do not have the ability to not choose in order to exist."

    That looks more grammatical. It says A => B, where A is "we do not have the ability to not choose" and B is "we have the ability to choose ". However, there are two bits of the sentence that I cannot fit into a grammatical structure: C: "I found that " and D" "in order to exist.". Is C to be grouped with B, as in A => I found that B? C is clearly a modal operator, but I don't know how you intend to bind it. Is it C(A=>B) or A=>C(B)?

    And what about D? Is it to be grouped with A, as A in order to exist => B? But A "in order to exist" does not make sense! One can analyse D as (- => will exist), so it is a part sentence, but where does it fit in? I have not a clue.

    Whatever you are trying to say is hopelessly undermined by failures of writing.

    And of course it looks nutty, but that's really secondary to not being able to read it in the first place. If you could get yourself writing better, you would have a less hard time.

    I think it's unfortunately odds-on that this is wannabe stuff, in the infamous Ludwig Plutonium line of physics.

  • What are the main markers of T-cell activation?

    Hello, I'm trying to evaluate markers to establish change in T-cell status from naive to activated after I have stimulated them with a specific protein. Can anyone guide me on how to assess this?
    Thank you

  • Guillaume Lemaître added an answer in MATLAB:
    Is there a minimum breakeven threshold regarding the objective function time to have the parallel cpu optimization faster than the sequential one?

    I have an objective function that takes about half a minute to execute. I used Matlab optimization toolbox. I found that sequential versions of the algorithms (Multistart, Genetic, PSO) are faster than parallel ones. Any explanations??

    Guillaume Lemaître · Universitat de Girona

    It happens to me in Matlab when the process in the parfor was "light". The reason is explained there (http://www.mathworks.com/matlabcentral/answers/32460-parfor-slower-than-for-for-simple-tutorial-example) and is due to overhead to send and collect result and the synchronisation of the processes.

  • I would like to find the association between 2 set of point data in 1 area. Can you please suggest me what statistical analysis that I can use?

    I have point data of 4 different variables. 

    I would like to answer my null hypothesis 'There is no association between 2 variable statistically significant.

    Juan Carlos Saravia · Pontifical Catholic University of Peru

    Hi,

    Could you please give more information? The answer could be a dependent t-student up to comparing models using maximum likelihood ratios. 

  • Patrick Druggan added an answer in Gnetum Gnemon:
    How can I calculate the MIC value with a well-diffusion method?

    I've some trouble in calculating the MIC value because the outcome didn't match the theories I know. I currently doing research about the antimicrobial activity of gnetum gnemon extract against Eschericia coli and Bacillus cereus. Thank you before.

    Adi,

    The method might be limited by your dilution series. If you have used those concentration as stated in the paper you have a five fold difference in the standards that have your antimicrobial agent, and I think you will have will not have a straight line. Have you carried out a residuals plot to check for curvature or outliers? How many replicates have you used per standard?

  • Gamal Abdul Hamid added an answer in Comorbidity:
    What is the practical utility of assessing co-morbidity in cancer patients?

    Co-morbidity is any other illness apart from indexed disease

    Gamal Abdul Hamid · Aden University

    Co-morbidity is a disease or illness affecting a cancer patient in addition to but
    not as a result of their index cancer.

    Co-morbidity is important for cancer patients for : 1. Clinical decision making
    2. Risk adjusted outcomes analyses
    3.  Highlighted in the CRS

    Charlson Comorbidity Index:

    Is used to assess comorbidities in cancer studies.
    Individual tumour level
    Analysis needs to be undertaken to assess
    The best approach to calculating co-morbidity from data  available

  • What does a negative peak in a UV spectrophotometer reading suggest?

    I am carrying out a degradation study and I am scanning the media extraction from 190-300 nm. At 0 Hrs I get a peak at 230 nm and 265 nm. But after 24Hrs the 265 nmpeak decreases while a negative peak is observed at 230 nm i.e. a small peak below the base line. I am using methanol as blank and I am using methanol in baseline measurement.

    Fabio Granados-Chinchilla · University of Costa Rica

    Hey there, what mobile phase composition are you using? And in what solvent did you prepared  your sample? Is your negative peak at the beginning of the run or mid run? Usually VWD should not give negative peaks unless you set the polarity to do so or otherwise in very specific cases (however in both cases all peaks should be neagtive). Generally, mid run negative peaks are due to a mis-match between mobile phase and injection solvent (% water composition?) which reduces scattering in the mobile phase especially when acid is involved. On some ocassions, a negative peak may be caused by an impurity present in the solvent. It is possible you are working in the sensitive range on your detector and you are able to detect impurities as they elute. You should check if your solvents are HPLC grade, are they filtered, have they been contaminated?

    Hope this helps

  • Anyone knows this sequence: (n-k+1)*(n-k+2)...(n+1)/(n-k)! for fixed n?

    I'm looking for properties of the following sequence for fixed n>=k

    (n-k+1)*(n-k+2)...(n+1)/(n-k)!

    I'm especially interested on bounds of sequence elements.

    Jerzy Baranowski · AGH University of Science and Technology in Kraków

    In an L2 approximation problem i'm working on coeeficients of approximating sum are computed using this sequence (actualy a sequence that is reducible to it). When order of approximation rises the numerical computation of factorials becomes troublesome and introduces errors. I was looking for a way of more numerically robust formula. 

  • Bran Black asked a question in OsiriX:
    Has anyone used CT scans to get good density trace for marine (or other) sediments?

    Hello everyone,

    Have any of you used CT scans of sediments to get a density profile/trace? Specifically, I am working with marine and lake sediment cores. I have used CT scans before for their imagery and have exported profiles of their densities based on their grayscale values in ImageJ, Sante DICOM Viewer, and Osirix, but we'd like to move into using our CT scans a bit more quantitatively. I processed the dicom files with the same window and level settings within individual cores, but was not always able to use the same settings from one core to another when I created images (.jpegs, .tiffs, etc.) from the dicoms (sandier cores would be washed out or muddier cores would be too dark to see detail otherwise). Now, though, we'd like to access the actual, or as close to actual, densities as possible. I've read a little bit about calibrating CTs to a known value (I was thinking air that got imaged around the cores, or their PVC/plastic core liners) and about using the Hounslow scale to at least approximate actual densities. I was wondering if a) anyone's got any thoughts on finding good ways to tie CTs to actual densities, and b) if anyone can think of any pitfalls to watch out for while I do this.

    Thank you for any help or suggestions you can give!

    - Bran

  • How can I increase gain of differential amplifier?

    We know that in differential amplifier which is is based, if we reduce the dimension of pmos transistors gain increases, but I can't able to get the concept behind it. Why does it happen?

    Alexander Pchelintsev · Tambov State Technical University

    This can be achieved by changing the resistances of voltage divider of operational amplifier.

  • Mohammad Samaaneh added an answer in Abaqus:
    How do I deal with unconnected regions in my Abaqus model?

    Hi all,


    I have a problem in defining contact. There is a 3D composite wall model . I have used Surface to Surface contact. I receive these errors:
    1-There are 3 unconnected regions in the model.
    2-There is zero FORCE everywhere in the model based on the default criterion. please check the value of the average FORCE during the current iteration to verify that the FORCE is small enough to be treated as zero. if not, please use the solution controls to reset the criterion for zero FORCE.

    Any idea is appreciated
    Regards
    Mahya

    Mohammad Samaaneh · King Fahd University of Petroleum and Minerals

    I tried to fix it ....... define the boundary conditions to start from initial not from step 1 because boundary has to start from initial

    2nd thing is the constraint ...... I think may you need to model it not like embedded element

  • Nasim Maleki asked a question in Electron Transfer:
    Whats the standard dimensions for Potential and scan rate in Laviron's equation for calculating electron transfer rate constant (Ks) ?

    When drawing a curve of E peak vs. log (scan rate), what dimensions should I use? because when I use V for both, number of electrons transferred is n=2 and a small Ks about 0.03, and when I use mV, n= 0.02 and since then another equation applys ( for nEpeak< 200 mV) then Ks becomes almost 3.

    I also have seen paper with E(V) and scan rate(mV) used in the curve.

    Thanks in advance

  • How to transduce AAV?

    I'm attempting to transduce enteric nervous system (ENS) neurons and glia via an AAV8 vector with eGFP genetic material. I would like to do so both in culture as well as in vivo (e.g. via tail vein injection). Does anyone with transduction experience have advice on how I might approach this?

  • Regit Mail added an answer in Polyaniline:
    What is the effect of HCl concentration and doping time on PANI film conductivity?

    i disperse PANI (emeraldine base) in NMP (100 mgr of PANI in 3 ml NMP)

    then i dry the glass petri dishes containing the above solution (110 oC for 4hours)

    the final step i have only HCl

    i want to dope these casted film

    i want that my final product have the highest conductivity

    the issues are following:

    1. what are the best HCl concentration?

    2. how many hours do i need to dope the film having the highest conductivity?

    3. i want to obtain the HCl-doped film with the highest conductivity but i don't know the time and the concentration for doping process

    4. i have only HCl ...i want to dope just with HCl

    best regards,

    Regit Mail · Tek-Dev

    @Kannaiyan, You can see in our patent mentioned above that we did the synthesis at about -10 C. We compared using HCl and methane sulfonic acid (and other acids) in the synthesis and found the MSA resulted in the highest conductivity in the final product. (And also when the emeraldIne base form was was doped with various acids, MSA gave the highest conductivity, possibly due to a "memory effect" when using the same acid for both synthesis and doping.) For highest quality and conductivity, HCl do pant is not recommended.  If you just need some "OK" conductive PANI, then HCl dopant could be OK.

  • Which Information Security framework / standard/certification/guide is best for cloud organizations to maintain their security?
    There are several Information Security frameworks, standards, certifications and guides to maintain security in an organization.
    Would you share which one is best for said purpose?
    Vito Santarcangelo · Centro Studi , Buccino (SA), Italy

    The ANNEX A is in the final pages of ISO 27001:2013. Annex A is a list of great importance to carry out checks and implementations related to information security. It is a list of 114 controls (best practices), grouped into 35 control objectives, which are grouped into 14 key points, labeled from A.5 to A.18. You can find the implementation of Annex A in the ISO 27002:2013.

  • How should we measure the working alliance in psychotherapy research?
    When should we use observationally measured ratings of the working alliances (therapist and observer) in psychotherapy research, and when should we use patients’ self-reporting?
    John Christopher Muran · Adelphi University

    I just came across the following, but you should contact Tim Anderson for a copy:

    Andrew Darchuk, Victor Wang, David Weibel, Jennifer Fende, Timothy Anderson, Adam Horvath (2000). Manual for the Working Alliance Inventory – Observer Form (WAI-O): Revision IV. Department of Psychology, Ohio University.

  • Where can I find the Working Alliance Inventory - observer version (short)?
    I'm wanting to use the Working Alliance Inventory - short (12 item) observer version, as part of a research study we are conducting here in the UK. I'm looking for a rating manual - I've got the 4th edition (2000), but am looking for one of the earlier versions, as the rating system was changed from the 4th version onwards, and we're needing to use an earlier version... This is part of our work on an RCT examining treatment of adolescent depression. Thanks!
    John Christopher Muran · Adelphi University

    There is also a WAI-O manual by the following, which I just came across, but you should probably contact Tim Anderson for a copy:

    Andrew Darchuk, Victor Wang, David Weibel, Jennifer Fende, Timothy Anderson, Adam Horvath (2000). Manual for the Working Alliance Inventory – Observer Form (WAI-O): Revision IV. Department of Psychology, Ohio University.

  • Patch antenna modelling using phased.CustomAntennaElement system object in phased array system toolbox in MATLAB 2014a

    How can I model a patch antenna with a gain of 9dbi at 5.8GHz using the phased.CustomAntennaElement system object in phased array toolbox of MATLAB 2014a. I have read the documentation but dont get it right. How do I specify length,width,etc, and calculate gain.

    Perhaps a simple example will help.

    Any help will be appreciated. Thank you.

  • Nelson Souza added an answer in Saccades:
    What is the best eye tracking device under 400 dollars?

    I need to buy an eye tracking device to use in an experiment in which I will have to track:

    a) the gaze movements of someone tracking an object moving on the screen

    b) the saccades between text segments

    Nelson Souza · Federal University of Pará

    Dear David, Matthias, Xuelian and Andreas, your answers helped me quite a lot. I bought the "eye tribe" device. I will soon give you feedback on your fantastic answers..  

  • Linh Nguyen asked a question in ETABS:
    How to convert Push-over curve (Base shear-Roof displacement relationship) to bilinear form?

    By using Push-over analysis in Etabs and Perform 3D, we get Push-over curve (Base shear-Roof displacement relationship).

    How to convert that Push-over curve to bilinear form to get the values of Base shear and Roof displacement at yield point?

  • Thomas Glonek added an answer in Obesity:
    Is there a statistically valid relation between weight and the duration of surgery?

    As there is a higher risk at least for infection, the longer the surgery, it should be the same with obese patients, if their surgery take more time. If this is not the case, it would be worthwhile to find the reason, for some kind of protection against infection.

    Thomas Glonek · University of Illinois at Chicago

    I am not aware of a formal study correlating length of surgery to weight loss. There is, however, a definite correlation between length of bed-ridden and weight loss. One looses about 7% muscle mass during a good overnight rest. A patient bed ridden for a month can easily loose 40 lbs and be practically unable to rise out of bed under their own power when it is time for them to get moving, this requiring extended rehabilitation with full recovery not ordinarily attainable. I know, because it happened to me.

    There must, however, be a (statistical) correlation between weight loss and length of surgery, because long surgeries usually require more bed rest.

    Tom

  • Which topics in a business strategy course would be well supported using lecturer screencasts?

    I want to develop short screencasts to help my business strategy final year undergraduate students to achieve deeper learning or to give them the ability to revise tough lecture elements. Which topics/ subtopics would be the best ones to start with?

    Guillaume Lemaître · Universitat de Girona

    I think that the Canvas Business Model is coming an important tool ad Porter's 5 Forces for 20 last years. You can find material there: http://www.businessmodelgeneration.com/canvas/bmc

    Some extra information there: https://drive.google.com/file/d/0B-DJ98-Q1GtpWXpHQnRMdjJCNTg/edit?usp=sharing

  • Someone will have some reference (article, book) with the recommended daily intake of antioxidants (polyphenols) ?

    I know it's complicated topic, and there are many contradictions about it, but some reference value should exist...

    would appreciate your help.

    Mohammed Cheurfa · University of Hassiba Benbouali Chlef- Algeria

    http://www.hindawi.com/journals/omcl/2012/906252/

  • Mario Toubes Rodrigo asked a question in Plate Reader:
    Does anyone knows how to identify fungi using BiOLOG plates without using their microstation?

    I'm planning to use biolog plates to identify microorganisms (both bacteria and fungi). I have a Thermo plate reader, which was really useful to read the Eco plates. I'm planning to jump into their identification plates, but for fungi you need this really expensive microstation, so I would like to know if anyone has used this fungi plates with a more affordable platform. Kind regards

  • Does anyone know if GFP or RFP withstands fixation during FISH?

    I would like to visualize the RFP signal after performing the FISH protocol, but I am thinking that the paraformaldehyde fixation would not work with RFP. 

  • Dahlia Karto added an answer in Photosynthesis:
    Where can I find a database of C3/C4/CAM photosynthesis pathways of European plant species?

    A great dataset is accessible from http://taxonome.bitbucket.org/grasses_ptype.html to use in Taxonome 1.5 or other way dealing with json format (I imported the dataset in R for my own convenience). But I'm looking for a similar source of info for European species ... so far I couldn't find that.

    Any tip?

    Dahlia Karto · State University of Malang

    open please the text book plant physiology

  • Menakhem Ben-Yami added an answer in Abundance:
    Do you know of any examples of invasive species which are less abundant than predicted?

    I am interested in exploring examples of invasions where the invader was ultimately *less* abundant or successful than initially expected based on predictions or other invasions by the same species.  

    One example we have in Washington State is the European green crab, which was initially expected to be extremely abundant and problematic, but was/is ultimately held to very low abundances by biotic and abiotic factors. 

    I know there are many examples of unanticipated, qualitatively positive effects of invaders, but I am more interested in influences on variability in the numerical success of invaders.

    Thanks!

    Menakhem Ben-Yami · Freelance Consultant, Tel Aviv, Israel

    Well, in our case (see Reference) we had substantial 10-11 years fluctuations in the abundance of the invading lizardfish, interchanging with that of a native hake, with which it was sort of struggling over a niche. In fact, it was probably an effect of environmental, mainly thermal fluctuations. A post scriptum to the 40 years old paper is that the native hake disappeared, and the invading lizardfish was joined by more invading species, so that the composition of the present population of the demersal commercial fishes has totally changed, and the first invader hasn't "enjoyed" the disappearance of its native competitor, apparently, due to expansion of additioanal invaders. 

    See: Ben-Yami, M. and T.Glaser.  The invasion of Saurida undosquamis (Richardson) into the Levant Basin - an example of biological effect of inter-oceanic         canals. Fish.Bull.(USA), 72 (2):359-373.1974.

  • Can anyone suggest how the ecological functioning of PETM and Early Eocene climatic optimum can add value to E & P of hydrocarbon?

    Distinguished Colleague, am working on the ECOLOGICAL FUNCTIONING OF ZOO AND PHYTOPLANKTON COMMUNITIES ACROSS THE PALEOCENE-EOCENE HYPER THERMAL EVENTS. Can anyone suggest how this can add value to petroleum exploration and production?