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  • How do I fit a quadratic model using design of experiments?

    I am performing DOE for 3 variable problems and I want to fit a quadratic model in order to find the optimum.

    How can I do this ? Can i use the results of DOE (full factorial) to do the same ? 

    Martin Guillermo Cornejo Sarmiento · Pontifícia Universidade Católica do Rio de Janeiro

    First of all, you need to define the experimental designs that you will use. I suggest to use The CCD (Central Composite Design). In the case of your experiment (3 factors and 2 levels) you need: 8 factorial points, 6 axial points ((+/-alfa,0,0);(0,+/-alfa,0);(0,0,+/-alfa)) witha alfa=square root of 3, and 2-5 central points (0,0,0)
    With this design the process of optimization is easier.

  • Yung-Chang Chen added an answer in APACHE:
    Most of ICU acuity scores assess the first 24 hrs (APACHE II, SAPS II, etc). Do you know if they can be applied sequentially?

    Those scores can be applied to assess patient´s evolution of his/her acuity?  Or they´re designed to be applied just at admission?

    Yung-Chang Chen · Chang Gung Memorial Hospital

    May consider the followings:

    1. Scores used on ICU admission: patients' severity

    2. Scores used at 72-h after ICU: response to treatment

  • Can anyone help with IHC free floating 30um brain cryoslices fading on both sides?

    Hi everyone, I have a bit of a dilemma. I've been doing IHC for a while and it wasn't until recently that this problem caught my attention. I do 30um free-floating brain cyroslices and incubate with Iba-1 (Wako rabbit or abcam goat).

    I always seem to get less depth than 30um, and it's always the centre portion of the tissue that I get the stronger signal from (I get about 16-17um normally). I have also had an issue where the top side of the brain (the side facing the coverslip) can become patchy looking. What I mean is as I zoom towards the coverslip some dark patches in the brain will get larger and darker, while some really bright areas will continue to be very bright (continues for a few um's).

    Here's my protocol:

    Block for 1hr (5% normal donkey serum, 0.3% triton, 0.03% NaN3)

    Wash with PBS 3 times, 5 mins each.

    Primary incubation (Assay diluent: 1% normal donkey serum, 0.3% triton, 0.03% NaN3) overnight RT parafilmed to avoid drying

    Wash with PBS 3 times again

    Secondary incubation for 2 hrs (Assay diluent same as Primary)

    Wash with PBS 3 more times, last wash is 15 minutes.

    Mount onto slides, let dry and fluoromount is applied. Then tissue is coverslipped.

    When I saw the centre portion bright, I was suspecting washout from both sides. When I take confocal images I crank up the gain to the point of just below saturation and measure my slice. However when I crank up the gain past that point I can get a good few um on both sides of my tissue.

    I suspected too much Triton, since I used to add 0.3% Triton in Blocking, Primary and Secondary. So I did a Triton test with 0.3% in all steps (original protocol), 0.3% in Blocking only, 0.1% in Blocking only, 1% Permealization for 20 minutes and no more triton afterwards. I imaged the brains 3 days later and found my 0.3% in Blocking only gave a good 26 um (But useable probably 23ish since the ends were dark).

    I started doing some other experiments using 0.3% in Blocking only, however both of the subsequent experiments I got 17-18um again! I re-checked my Triton test slides from the previous week, and to my surprise they also became 17-18um. The only difference in my subsequent experiment was that I didn't add quite enough medium (the medium dried really fast for me to apply nail polish, if I add too much the coverslip can move around so I can tell if the medium is still wet).

    I'm at a loss here. I am considering trying to use more medium, and not dry my slides as much?... I see people talk about coverslipping when slices are wet. I did a test on that and the wet slices roll/ fold/ become wavy when I add the medium. They just won't stick to the slides. I may just re-make all my solutions to see if there was any contamination... Getting a little desperate here. So any help would be greatly appreciated!!

    Jill Miotke · University of California, Irvine

    Hi Tian,

    I have hopefully attached the two files with the mounting media recipes.  The one I use is the Heimer & Taylor recipe. 

  • How can i prepare a standard callibration curve for a compound using 1H NMR Spectroscopy ?

    I mean I wants to know which parameters can I consider with different concentration of an analyte?


    -Peak height?



  • How can I make a vacuum chamber completely oxygen free? Is it really possible to make a vacuum completely oxygen free?
    Calculations show that even if I make the vacuum chamber as low pressure as 10^-8 atm, still there is lots of oxygen. Can anyone suggest any chemical/any other process to make the inside of a vacuum completely (at least the most it is possible) oxygen free?

    Or, can anyone suggest me any other method to protect the metal to be fabricated from oxygen?
    David Arnold Lamothe · Canadian Food Inspection Agency

    Check out food storage sites for oxygen absorption packs.

    These might meet your needs

  • Is there a method other than reverberation room and standing wave tube to find sound absorption coefficient?

    In the following attached paper he said there are lot of methods to find sound absorption coefficient , if anyone knows update me

    Hector Garcia Mayen · San Buenaventura University

    You can take a look at Microflown Technologies Impedance Gun.

  • B.R. Parekh added an answer in Power Transmission:
    Which frequency is better for power transmission -50hz or 60Hz?

    Please explain the advantages and disadvantages of both.

    B.R. Parekh · Birla Vishvakarma Mahavidyalaya Engineering College

    1. flux = voltage / frequency. As frequency increases, flux requirement reduced for same voltage and hence size and rating of the machine (or transformer) reduced for same rating.  

    2. As frequency is more, synchronous and hence rotoe speed is more. 

    3. Efficiency, regulations and other performance parameters remain nearly same as machine is designed for same performance parameters.

  • Yang Liu added an answer in RNA-Seq:
    How can I get the differentially expressed genes in cancer cell lines?

    I'm wondering is there a way to calculate the differentially expressed genes in cancer cell lines(e.g.,MCF7)? The gene expression data (microarray or RNA-seq) for cancer cell lines can be found in many projects, but corresponding normal cell does not exist. Is it sound to use the corresponding normal tissue(e.g.,breast) gene expression for the calculation, such as the Illumina Body Map? Or is there any project to characterize the genome features of these cancer cell lines?

    Yang Liu · Beijing Institute of Radiation Medicine

    Yes, using cancer cell lines to characterize cancer is only an approximation. @Sandeep Rajput, I'll do that.

  • Akira Kanda added an answer in Theoretical Physics:
    I have some opinion about theoretical physics. What is a suitable way to share it with physicist and chemist?

    I have some new interpretation about physics experiment from chemist view. This can explain many basic physics concepts, like charge, interaction or force, movement etc. what is a suitable way to expose my idea?

    Akira Kanda · University of Toronto

    Dear, Panagiota,

    As a mathematician, I know well that due to the large number theorem no probabilistic predictions can be either verified or refuted by experiments. We can not repeat the same experiment infinitely many times. So, I do not understand what do Quantum Physicists mean by experimental verification of QM.

    De Broglie relation fails even for photons: It is a basic elementary mathematical error Einstein made.

    Einstein thought that the problem of diverging relativistic mass and energy of the photon  due to its speed c can be resolved by assuming the rest mass of the photon to be 0.

         *To begin with only totally incoherent thinkers will consider the rest mass of a particle who is always in move in any reference frames. If this makes physical sense, I wonder that physical sense means.

         *His argument goes as follows. Einstein thought that the problem of relativistic energy


    is undefined when v=c. So, he proposed to set m0=0 for a photon.  From this convention, he obtained e=0/0.

    He thought that 0/0 is indeterminate  and decided to fix this value to the desired one as follows:


    So, he obtained




    where lambda is the wave length of the photon.

    There are two elementary mathematical errors which cooked the entire theoretical physics of the last century.

    p=mv=m0v/sqrt(1-(v/c)2), and so for photon e=cp=0/0.
    0/0 is not indeterminate. Indeed it is not a number, it is undefined. This we can see as follows: Assume 0/0 is a number then (0/0)*3=1*3=3 and (0/0)*3=(3*0)/0=0/0=1. So, we have 3=1.
    This argument kills Einstein's relativistic theory of photon.

    The misunderstanding took place because Einstein and his followers thought 0/0 is indeterminate because the solution to the equation 0*x=0 is indeterminate. x indeed can be any number. But from this equation x=0/0 does not follow. We can not divide by 0.

    So, let me ask you one more time. This pure mathematical nonsense of the de Brogli relation on photons make physical sense to you physicists?!

    When the theory has this kind of obvious errors, what can you do about it with experiment? This is the basic question Popper asked. He said that we must abandon logically inconsistent theory just categorically. I think he is correct.

    May be Compton effect is telling us something important, but I am absolutely sure that it has nothing to do with Einstein's relativistic theory of photons.

  • Nicolás Cuesta asked a question in Coherence:
    Does anyone know any paper or study that actually measures the policy coherence for development (PCD) in the EU??

    I'm having a lot of problems regarding the operationalization of PCD for the EU institutions level, for my bachelor's thesis. I neither have time nor resources to develop my own measurements of policy coherence.

  • Lauren M. Wolf added an answer in Microglia:
    Is it appropriate to use myeloid-derived cell line like PBMCs to develop an inflammation for microglia?

    I'm trying to develop inflammatory assays for microglia, but these cells are expensive and difficult to come by. Is it alright to use an inexpensive myeloid-derived cell line like PBMCs to develop the assays--they would have similar cytokine secretion and cell-surface markers, would they not? Thanks in advance.

    Lauren M. Wolf · University of South Carolina

    I think the THP-1's will be okay just for assay development--they're cheaper and reproduce more readily. I think the jury's still out as to whether microglia descend from HSCs as other macrophages, but it looks like the HSCs and the microglia share an erythromyeloid progenitor. Again, this is assay development. I appreciate all the help from everyone.

  • Ks Goi asked a question in Attachment:
    Is it I should ignore all main effect since I have an significant interaction of ABCD?

    As shown in attachment, the minitab tutorial mentions that if there is interaction between factors then the main effect of single factor can be ignored. If I have the situation as shown in attachment.

    ABCD 4 way interaction is significant. 

  • Ananda Kafle added an answer in Optical Microscope:
    How can I see water in a phosphatidylcholine sample under a polarizing optical microscope in cross Nicole conditions?

    I frequently find authors claiming the presence of water in a sample by indicating some black spots in POM textures. But such black spots can be possible in many cases of isotropic phases and hence, do not sound convincing enough. Can anybody illustrate this in little more detail ? 

    Ananda Kafle · Kathmandu University

    Thank you very much Dickson. 

  • Edward Siguel added an answer in Fatty Acids:
    Can anyone suggest an optimum lab protocol for fatty acid analyses of red blood samples?
    Washed RBCs need to be stored for at least 2 months. Washing solutions differ. Is the addition of BHT critical at this stage or if liquid nitrogen processing is used, can it be omitted? Then, would the addition of BHT still be required during the solvent extraction stage?

    The analysis is very tricky. Oxidation is common and changes the FA profile.

    working with BHT at the rate of 0,1% (w/v)  in solvent, and to following Lepage & Roy (1984) methodology for direct esterification (see above). Then one has derivatives of BHT and cholesterol (among others). Depending on the column and method used, they are likely to elute superimposed with other FAME.

  • David Dunaetz added an answer in Attitude Change:
    How can social psychology foster students, motivation through attırude change?

    social psychology, attitude change, demotivation

    David Dunaetz · Azusa Pacific University


    Please clarify. Do you mean. . .

    1. How can taking a social psychology class change students’ attitudes so that they are more motivated to work harder?

    2. What theories from the field of social psychology predict that attitude changes lead to changes in motivation, and how can this theory be applied to in school contexts?

  • Richard Chen added an answer in Water Sampling:
    Is there a guideline for water sampling during a water tracer study?

    the water tracer study is conducted for a pond, I need to collect samples to create a dye concentration curve at the outlet, what is the ideal interval for collecting samples? Is there a guideline. 

    Richard Chen · Griffith University

    OK, Thanks.

  • Do we need to induce unsteadiness via boundary and initial conditions in an unsteady flow simulation?

    Hello. Lets say I am using unsteady RANS to simulate my flow and I need to capture the periodic vortex shedding of a flow around a profile. For this, will my CFD code automatically capture the unsteadiness and provide a periodic solution of the vortex shedding or do I have to induce unsteadiness via Boundary / Initial conditions.

    Tapan K. Sengupta · Indian Institute of Technology Kanpur

    Could not agree more with Andres. This was the gist of my previous answer where I said that how the problem should be viewed as a problem of scientific computing mimicking natural route. RANS is an absolute "no-no" for such problems. Unfortunately managers want colourful pictures and over-eager engineers provide the same. 

    Ideally, one must obtain an equilibrium solution and then study its stability and/or receptivity to different classes of omnipresent background disturbances. Our cited references will tell interested people how it is done computationally.

  • Sherry Bhalla added an answer in Proteome:
    Proteogenomics using already available datasets of proteomics and RNAseq?

    I am new to the field of proteogenomics. I want to reanalyse already available proteomics data using already avalable RNAseq data in various databases.Is it logical because  proteome and transcriptome are both time dependent and vary if proteome data and genome data will be from different sample.

    Sherry Bhalla · Institute of Microbial Technology

    Hi and thanks for your suggestions sir Florean 

    I am going to compare proteomics data to the RNAseq from same organism but sample source is different like in most of the studies of proteogenomics they have taken a sample from an organism say human and did its proteomics and sequencing experiments  and then analysed the data. My query is, is it fine to compare a proteomics data from some "x" human to the RNAseq data gathered from some "y" human.

  • What are the differences between self-regulated learning and approaches to learning?

    I am wondering, if i would like to look at how the way a course is taught can influence student's self-regulated learning, and their approaches to learning, should I seperate the two studies? Or they can be integrated? Can someone with the knowledge of what factors in learning and teaching influence self-regulated learning point me to some key literature?

    Catherine Zhao · University of New South Wales

     I am amazed that in early childhood education approach to learning and self-regulated learning are linked together. What is the overlapping conceptual ground that supports linkage?

    On the other hand, Debra, thank you for the lit review list. A lot of them are directly relating learning and teaching design/activities to SRL. Are you suggesting approach to learning is mediating in between or SRL and AL are largely overlapped?


  • Why two additional Majorana phases are introduced in lepton mixing matrix?

    We do not know whether the neutrino is a Dirac particle or a Majorana particle. If neutrino turns out to be a Majorana particle then two additional phases are to be introduced in the 3x3 lepton flavor mixing matrix. Why these phases cannot be removed by field redefinitions. In the two generation case, we know that in the CKM matrix there is no CP violating Dirac phase. Similarly, will the Majorana phases disappear in the two generation case, or, will they continue to be non-zero even in the 2x2 mixing case. In which experiments will they show up.


    1. J. Schechter and J. W. F. Valle, Phys. Rev. D 23, 1666 (1981)
    2. J. Schechter and J. W. F. Valle, Phys. Rev. D 22, 2227 (1980)
    Biswajoy Brahmachari · Vidyasagar Evening College, 39 Sankar Ghosh Lane, Kolkata 700006, India

    @ Sebastian

    Correct. As UPMNS matrix is sandwitched between left handed currents, these phases are first absorbed in left handed fields. But then because the mass term connects left to right, phases are transferred to right handed fermions. They never reappear because there is no right handed mixing in the standard model.

  • Ehsan Baha added an answer in Personality:
    What is the most difficult challenge for a human?

    Personal question.

    Ehsan Baha · Technische Universiteit Eindhoven

    Dear Marceio,

    The question that you have asked is very intriguing. I would like to provide an answer based on Sufism:

    The most difficult challenge for a human is to become complete. By complete I mean close to divinity. In persian 'انسانِ كامل', in arabic 'اَلإِنْسَانِ الكَامِلْ', read as: 'al-Insān al-Kāmil'. According to Rumi, Hafez and other Sufi scholars/philosophers, one needs to get rid of one's own veil. That is, everything that one has build in oneself against love. To quote Rumi: "Your task is not to seek love but to remove everything within yourself that you have build against it."  

    With regard to humanity, I would like to add the following poem from the wisdom of Saadi:  "Of One Essence is the Human Race, Thusly has Creation put the Base.

    One Limb impacted is sufficient, For all Others to feel the Mace. The Unconcern'd with Others' Plight, Are but Brutes with Human Face."

    And I close my answer with a quote from Saadi as well: "Have patience. All things are difficult before they become easy."

    Kind Regards,


  • Edward Siguel added an answer in Fatty Acids:
    Does the human body have a mechanism for storing EFAs or EAAs ?

    Can the human body distinguish essential and non-essential fatty acids or amino acids, or does it simply indiscriminately burn what it finds in the bloodstream depending on the body's needs at the moment?

    There are two main "storage" systems for EFAs and their derivatives. I coined the term essential fats = EFA + DEFA (FA derivatives from EFAs).

    Membranes have essential fats for their function; they are not there for storage in the sense that we use storage as a place where we keep surplus when we need them.

    However, if there is a deficiency, the body recycles things. Will do it for amino acids and likely for essential fats.

    Adipose tissue is the storage form for FA. The main FAs in fat storage are the EFAs, not the DEFA, and saturated FA. Notice that humans do not store extra EPA, DHA, ARA. Instead, they store ALA and LA.

  • David Dunaetz added an answer in Mediation:
    How can I distinguish between mediator and moderator variable?

    I need any one explain in detail what are difference between mediator and moderator variable

    David Dunaetz · Azusa Pacific University

    Both help describe the relationships between two variables. For example, let’s suppose A and B are positively correlated; When A increases, B increases.

    Now let’s suppose there is a third variable C that interests us. If the relationship described above between A and B is only (or especially) true when C is high (and it’s not true when C is low), then we say that C is a moderator. Moderators change (moderate) a relationship between two variables.

    Now suppose we wonder if the relationship between A and B is true because variable D is causing it. If we have good reason to believe that A causes D and that D causes B, then we would say that D is a mediator. The relationship between A and B is mediated by D. Mediators are in between (mediate) two variables.

  • Is anyone familiar with PBMCs and PBMCs isolated from bloodbank buffy coat?

    I'm currently researching differences between PBMCs isolated from fresh blood and compare their ability to secrete IL-1 beta to that of PBMCs isolated from buffy coats coming from the blood bank. Is there a difference concerning cytokine secretion?

    Mikhail A Gavrilin · The Ohio State University

    Yes, fresh PBMC are better.

    However, when I propagate HIV, I stimulate PBMC with ConA and add IL-2 for 5-7 days. This boosts T cell proliferation and then I infect cells with virus.

  • Which paradigm(s) is(are) the most suitable for assessing the economy-environment relationship?

    Given the existence of different schools of thought within social science-at times complementary and at times contradictory-the debate over the way in which this relationship should be conceptualized and analyzed is a hotly contested one.

  • Sagar Desai asked a question in Affinity:
    Does CNO has affinity towards naturally occurring M4 receptors?

    Does CNO has affinity towards naturally occurring M4 receptors?

  • Michal Čermák added an answer in Insulation:
    Is anyone familiar with modelling of heat transfer of slab edge and its insulation of a house?

    Hello all, I am working with heat transfer modelling of slab edge and its insulation. Do you know what book or papers worth reading or any researchers' work worth following?

    Besides, are there any fundamental and comprehensive books about utilizing FEM or FVM to model heat transfer problems?


    Michal Čermák · Schlumberger Limited

    Hi John,
    It´s my guess, but a good guide in this area might be to go throught and seek for the original sources in publications of my colleague Dr. Pavel Karban and his scientific group. They develop the simulation software using FEM and FVM called Agros2d : http://www.agros2d.org/ .

  • Edward Siguel added an answer in Esterification:
    How can I prepare Fatty acid methyl esters of DHA oil ?

    i am trying to analyse DHA oil on GC , but i could not get any DHA peak. I think it is getting degraded , want to know any method for esterification of PUFA oil .??


    Why not use the Lepage method or some modern modification of it?

    I used it, with modifications, and got excellent results.

    However, accurate measurements of small peaks like ALA and its derivatives, is very difficult. One needs a combination of special technologies. A 100 m capillary column. Special extraction methods to minimize oxidation and artificial peaks. Long separation method (3 hours). Special purpose software to integrate peaks.

    Otherwise, flaw data may occur. Search for Siguel and Fatty Acids

  • Fawad Ahmad asked a question in Adsorption:
    Respected members How i can conduct an experiment for insitu-IR data for HMF (hydroxy methyl furforal) ?

    i want to study catalytic adsorption reaction of HMF to DMF.

  • Kindly upload on this page - Random Field Experiments in Agriculture - economic impact related papers?

    I am basically an Agribusiness professional, interested in Random Field Experiment projects. Kindly help me to start with this

    OK Ramappa,

    Designing expts for farmers in their fields is exactly the same in principle as designing expts anywhere else EXCEPT that it is vitally important to listen to what the farmers are saying and what is important to them. In my experience in such situations farmers adopt in 2 main situations:- 1. where their livelihood is threatened and they may starve or go broke if they don't change and 2. where they feel they are missing out on something that they think everyone else is benefitting from. An example is.the very rapid adoption of zero tillage when the price of fuel (and thus cultivation) goes up dramatically. If you can devise expts in their fields to help solve a problem or to increase their incomes, you will increase the likelihood of adoption.

    Reducing costs, increasing yields or improving quality (and thus price of the product) are good places to look for practices that might interest farmers.

    Good luck,

    Wal Anderson