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  • Ekaterina Vinnik added an answer in Ex Vivo Experiments:
    Rat brain with air bubbles in the ventricles - how can I get rid of them to avoid artifacts in the MRI scans?

    Hi! Has anybody come across the same problem? We are doing MRI experiments on the ex-vivo brains. Unfortunately all the brains that I have extracted so far have air bubbles inside :( It is air for sure - it causes artifacts in the T2*-weighted images.

    I tried leaving the brain in a skull ( just removed the muscles and skin, but did not extract the brain), and it is still the same! I do perfusion in a standard way.. (PBS/PFA perfusion, cutting the head with the guillotine, careful brain extraction).. yet here are those bubbles.. 

    Today I was double-checking there are no bubbles in the perfusion lines - it is almost certainly not the cause.. May be the guillotine? Or something else?.. I do it the same way as people in the institute do, but nobody yet has looked at the MRI images..
    I have just finished my experiment, and I have 30 rats to perfuse, and I am really worried they will have air bubbles and won't be usable... Any suggestions would be most welcome..

    p.s. attached image is the 1T image of the brain left in the scull.. 

    Ekaterina Vinnik

    Hi, Douglas, 

    thank you very much for the detailed answer! I wonder how do you transfer the brain from the storage liquid to the imaging liquid? We use fluorinert for imaging. Do you think it would it be ok to lift the brain in the air and move it to fluorinert or should I substitute the liquid and never let the brain be in contact with the air? 

    How much time does it take for a trained person to extract the brain under PBS?

    Do you by any chance know any papers/protocols which describe the procedure in detail? I would very much appreciate any tips and tricks..

    Thanks again


  • Stephen A. (Steve) Leybourne added an answer in Entrepreneurship Development:
    Is there any information flow between social networks and entrepreneurship?

    many researcher's had identified that social networks play an important role in entrepreneurial emergence but how this information flows from social networks to entrepreneurs? is there any conceptual linkage between them?

    Stephen A. (Steve) Leybourne

    Early stage Entrepreneurs need to leverage any and all resources to get their business ideas off the ground and running.  It is generally accepted that they utilise their 'network' to assist with this, and today many networks are relatively informal, and socially generated and linked.

    This means that the 'glue' that holds your network together is likely to be LinkedIn, Twitter, or connection with websites such as entrepreneur.com and Innovation Excellence.

    There are of course other 'physical' networks: here in Boston we have the MIT Entrepreneurship Forum, and a number of others.  These are also useful as they get people 'face-to-face' and act as a meeting place and idea exchange forum for entrepreneurs, venture capitalists, business angels, etc..

    However, all this is essentially 'social networking', whether you use the usual internet platforms or not...

  • Krishnan Umachandran added an answer in Survey Research:
    How do I determine your target population or correct respondents in survey research?


    Suppose that I am studying Purchase Decision of customer towards certain brand or product in a supermarket.

    My question is regarding the target population to be selected as my respondent if I am collecting a primary data through questionnaire.

    Is my target population will consist of any customer of the supermarket or just the supermarket customers who bought the product?

    I got different views towards this matter since some says I should take all customers and some says it should be only those who bought the product.
    Could you give me your point of view regarding this matter and the reason why?

    Krishnan Umachandran
    • Any customer of the supermarket - Existing & Potential Customer
    • Supermarket customers who bought the product - Existing Customers (New and /or Repeat)

    Normally a target population is considered to be those who affect the purchase of a product normally classified on

    • Buying Power
    • Class of Society
    • Gender etc.,
  • Agatha OMOKHEFE Aigbodion added an answer in Nurse's Role:
    Can anyone recommend any papers on the history of research nursing and the development of the role?

    I am interested in how the research nursing role has developed, particularly in the UK since the 1950s. Can anyone suggest any papers?

    Agatha OMOKHEFE Aigbodion


    You can also check on Burns, N., Grove, S. K.,& Gray, J.
    (2015). Understanding nursing research: building an evidence-based practice.

    Best wishes

  • Victoria Negro asked a question in Hieroglyphics:
    Could somebody recommend me any literature about egyptian hieroglyphics??

    I am highly interested on egyptian hieroglyphics, but I haven't found any didactical sources yet. Do you know of some of them? It doesn't matter the language nor the type of source (web, book, pdf...).

    Thank you very much.

  • Tom Shuttleworth asked a question in Likert Scale:
    I need some help regarding a question I'm trying to answer?

    The question asks 1) What type of design did the current study use. 

    I first thought it would be qualitative methods as there is a questionaire aimed at 15 year olds who drop out of sports clubs after school. The author wants to measure enjoyment and low competences, as independent variables and the dependent variable being there age, 15.

     But within the questionnaire there is a likert scale aimed from 1-7 1 being disagree completely and 7 being I agree completely. 

    The Hypothesis: There would be a significant difference between scores on Enjoyment compared to Perceived Competence.

    I've been looking at levels of data nominal, Ordinal, interval and ratio but there is no clear indercation of the correct test. 

    I'm currently looking at Mann Whitney test. or  Kruskal Wallis test. 

    Could anyone give me any suggestions?

  • Dason E Evans added an answer in Teaching:
    How can I help demotivated and tiresome students to become interested in learning and love the English language?

    I am teaching students who are not enthusiastic and don't like learning. I wonder how I can help them develop good attitudes towards English. Dear colleagues can anyone tell me how to deal with such a situation? 

    Dason E Evans

    I would agree with all comments, especially Khalil El-Saghir's summary. Might also add something about encouraging a positive attribution and self efficacy...

    "I'm terrible at French, in fact my whole family is terrible at learning languages, they are so innately difficult and my brain doesn't work that way..."

    At Medical school we have a similar problem, some topics are branded 'difficult' and students told 'you probably won't get this' and 'its dull and just something you have to learn'. Perhaps unsurprisingly these are the topics that the students then struggle with.

    So, helping students realise that their own efforts result in successes and failure, and that challenges can be exciting, failure is always part of learning, will help them learn. Often we reinforce negative messages with the way that we present material.

  • Amit Mittal added an answer in Corporate Finance:
    What theory explains the relationship between mergers and corporate debt financing?

    In recent times, researchers have been motivated to study the impact of mergers on corporate financing. The arguments establishing the relationship between mergers and corporate debt financing are convincing but it may be better to know specific theory or theories that explain the relationship. What theory explains the relationship between mergers and corporate debt financing? Please, identify such theory or theories (if any).

    Amit Mittal

    Did you check the original Myers and Majluf(1984) paper where they reflect mergers are caused by the quest for financial surplus, Such a theory would be especially germaine today and may drive out any preference for debt with cash acquisition for future investments/mergers

  • Gaurav Kumar Singh asked a question in Carbapenems:
    What is the best solvent for carbapenem antiobiotics? Water or DMSO?

    A very basic query regarding the solubility, stability and storage of carbapenems antibiotics such as Meropenem trihydrate or Imipenem monohydrate. I have known to dissolve them in DMSO in higher concentration for short storage periods but can we use water for the same? Does water affect the stability due to storage in the long run at -20 degree Celsius?

  • Suat Senol added an answer in Soil Classification:
    What is Inceptisols according to WRB classification?

    In my study site soil classification according to Soil Taxonomy is Inceptisols.

    Soil type is clay-loam.

    Horizon A: Depth= 0-15 cm; Sand= 33%; Silt= 41%; Clay=26%.

    Horizon B: Depth= 15-55 cm; Sand= 29%; Silt= 43%; Clay=28%.

    Horizon C: Depth= 55-85 cm; Sand= 26%; Silt= 42%; Clay=32%.

    The study site have Marl and Limey sand-stone.

    The parent material is calcareous and soil is leached brown forest soil.

    Suat Senol

    May also be Calcisol, due to existing of secondary carbonate accumulation.

  • Shiv Kumar Yadav added an answer in Organic Compounds:
    How I can remove the metals (Fe, Na, K, Ca etc) from my organic compound (readily soluble in methanol)?

    My organic molecules is highly polar and soluble readily in methanol. When I checked in AAS (and chemical method also) I have found some ppm level (2-10 ppm) of different metals (Fe, Ca, Na, K, etc.) I want to use this compound for some electronic application. How I can remove this metals from my sample at least to reduce the concentration of metals to ppb level? Can any one provide a better and easy way for this? Thanks

    Shiv Kumar Yadav


  • Fábio Macêdo Nunes added an answer in Inclusion Bodies:
    How do I get rid of inclusion body in protein purification?

    I have cloned a gene and tranformed it to E.coli BL21. Expressed protein are getting into inclusion body. Please help me to troubleshoot this problem.

    Fábio Macêdo Nunes

    Hi Amit,

    The problem of body inclusions normally are the action of heat shock proteins or some hydrophobic residues in your protein. So, when do you finish your centrifugation to get your cells pellet, put some lysozyme in your buffer before you resuspend your cells and freeze to stock it. Later, perform your lysis,make more pulses of sonication to break the membrane in less time and intensity on ice, put some DTT or beta mercaptoethanol and some tween 20 or triton (solve your problem with hydrophobicity ). if you work well you dont will need to refolding (less work, and activity troubles).
    Good luck.

  • Lutz von Wangenheim added an answer in Filters:
    Can anyone help me to make a elliptical or Cauer Filter (LC Filter)?

    i want to make a Cauer Filter using LC circuit. i mean i want both High pass and Low pass filters. Someone please help me to design those kind of filters.

    i dont have a cut to cut requirement,but i want to make one.

    Also i need the basic implementations of chebyshev or butterworth etc.

    Thanks in Advance



    Lutz von Wangenheim

    Arun - I think, the AD link provides ACTIVE topologies only, correct? And the AADE link works - however,  no access to the program because the author has passed away some weeks ago. However, I know that there must be some other web-based programs for passive filters. I will try to find a link.

  • Carlos Eduardo Barroso added an answer in Masonry:
    Does someone knows a good standard or publication about stone masonry durability or weathering testing using salts?

    We are studying schist vernacular masonry and, at the moment, we are preparing a durability test on small masonry specimens to better understand the effects of weathering and damage over time caused by salts. Due to the fragility of the test subjects (stone masonry with earth joints), we cannot submerge them, so we need an alternative way to test them. Any suggestions? Thanks

    Carlos Eduardo Barroso

    Hi Yasemin and Jesús. Thank you both for helping me. I was thinking on spraying the specimens with water with salt because of the very low water resistance of the earth mortars used. The problem is that all the standards i have, point out immersion as the weathering method. In a preparation test, we observed that the earth mortar in the joints are so fragile that it will be washed away in the first cycle. Only the earth infill in the inner-core might survive. Controlling the moister level in the joints is a very good idea, also to understand the level o penetration of the moister in the masonry. 

  • Shefaa Al Asfoor asked a question in Peritoneal Macrophages:
    Which is better : radio active glucose or fluorescent glucose for glucose uptake assay? and Why?

    Glucose uptake assay for Peritoneal macrophages:

    I want to apply glucose uptake assay on peritoneal macrophages after treating them with my drug. I have the following Qs:

    1- Which technique u will recomend : Radioactive or fluorescent glucose? and why

    2-Which medium u would use? With glucose , serum or without ?

    3-For How long you would starve the cells?

  • M.L. Fares added an answer in Tensile Strength:
    What is the process of stainless steel wire drawing from 5.5 mm to 1 mm?

    I have an 5.5mm of WireRod which is annealed&pickled. I am trying to draw that wires to 1 mm but something is going wrong. After first die, the tensile strength is getting increase 2 times of begining. What should be the process, anyone knows?

    M.L. Fares


    Janus's explanations are entirely accurate and correct; So,  you need to perform annealing to soften your material

  • Xola Caluza added an answer in Metasomatism:
    Is there a program "computerised" that can be used in alteration geochemistry particularly for mass balance calculations? If so,accuracy ?

    Ive been looking at a  manual way of calculating chemical mass changes in hydrothermally altered rock samples, explained by james Grant 1986 (Isocon diagram- A simple solution to Gresens' equation for metasomatic alteration) using Isocon diagrams

    Xola Caluza

    Thank you very much Soraya Hadjzobir ·

  • Gisela Gerardi added an answer in Microelectrodes:
    Does anyone have expetience with microelectrodes for measuring NO in biological samples?

    I have obtained ArrowStraight Nitric Oxide Measurement System (NO2/NO3) from Shelfscientific and have some questions about sample preparation etc. 

    Info is not that easy to obtain from the company, but anyway i'm interested in some "real life" experience.

    Gisela Gerardi

    We have recently acquired the NO measurement system and we couldn´t calibrate it. We have followed all the steps in the manual however the system indicates that the equipment is not calibrated. Do you can tell us the standards reference values? If the equipment is not calibrated,  is because the measure does not reach the standard reference values or there may be some other problem?

    Furthermore, after performing all the calibration steps, we tried to measure a sample problem but the measure did not appears on the computer, this is because if the system is not calibrated does not measure any sample or because there is a failure in communication?

    Thank you very much for your help!

  • Artur Braun added an answer in XRD Analysis:
    How to remove instrument broadening in XRD analysis?

    dear all, 

    i calculated crystalline size of my product, but in some research papers i found that authors have mentioned about removal of instrument broadening error.

    Please give me some suggestion to remove the same, so that i can calculate crystalline size accurately.

    Artur Braun

    You need to have measured a diffractogram with a standard material with high crystallinity and very sharp Bragg peaks (often silicon). This diffractogram is used for determination of the peak broadening which comes from the instrument slits etc. Then you have to make an "Entfaltung", a deconvolution of your XRD sample.

    Typically this is done with a software that comes with the instrument.

  • Navid Soltani asked a question in Abaqus:
    Does anyone know how to creat a non-linear elastic material type in ABAQUS?

    im wondering if its possible to apply non-linear elastic model on ligament(wire element)? there is so many material type in abaqus but i didn't find any kind of non linear using the toe-in region data.

  • Tony Maine added an answer in Solar Cells:
    Why is the Jsc of tandem solar cells are typically lower than Jsc of the subcell that produces lower current?

    I have read several papers about (organic) tandem solar cells, in some papers Jsc of tandem cell is almost equal to Jsc of the subcell that produces lower current and in some of papers Jsc of the tandem cell is lower. Which parameters cause lowering the Jsc of the tandem cell compared to the Jsc of subcell with lower current?

    Tony Maine

    Both Maetee and Abdelhalim have given excellent explanations of the effect. I would like to add some more practical aspects of this for real world cells. As you increase the number of cells in tandem, the more accurately you have to match the cutoff wavelengths to the exact spectrum of incident light. By the time you get to 4 layers, you will find you need to define the cutoff wavelengths to 1 nanometer for any given spectrum of incident light. You will find that a cell optimised to work when the sun is overhead is useless when it's near the horizon, and cells designed for normal incident sunlight won't work very well under xenon arcs, even though such an arc is a good match for the solar spectrum.

    While I wish researchers working on tandem cells well, it should be remembered that it is easy to overspecify such cells and find they do not work well in the real world. Their ideal application is of course spacecraft, which are exposed to full sun except when shadowed, and must have high (>40%) efficiency because of weight constraints.

  • Daniel Martin Schneider asked a question in Gold:
    Hat sich in der Literatur schon mal jemand empirisch mit dem Investorenverhalten von Gold-/Rohstoffinvestoren auseinandergesetzt?

    Hat sich in der Literatur schon mal jemand empirisch mit dem Investorenverhalten von Gold-/Rohstoffinvestoren auseinandergesetzt?

  • Petra Disterer added an answer in Primer Design:
    How can I get a primer to target FGFR2-IIIb isoform of FGFR2 gene for qRT-PCR in mice?

    My lab is looking to study FGFR2-IIIb expression in mouse mammary glands via qRT-PCR. I'm having trouble designing primers that will only target this specific isomer of FGFR2. How would I go about targeting this specific isomer or is there a primer design that already exists and is used by labs to target FGFR2-IIIb?

    Petra Disterer


    This is primer design for SYBRGreen separate PCRs for both isoforms. If you need TaqMan probes, you have to have them custom designed by Fisher.

    I find www.ensemble.org is best for working with alternative splice forms


    I find it helpful to do this:

    1. On ensemble select a transcript isoform, then in the lefthand menu, select "Exons" under the "sequence" item, then scroll down below the transcript variants table. This gives you the sequence of the selected transcript isoform. There's a download link, I prefer the RTF version and you can pick which bit you want included (I recommend to include 25 bp of intron sequence).

    2. Do this for both transcript variants. Then look at the sequences in these areas: IIIb should contain exons 7, 8 and 10, while IIIc contains 7, 9 and 10. You should see that there are distinct sequence differences in the exon borders as both isoforms contain different exons.

    3. Make two sequences that only include the exonic sequences from ~50 bp before the end of exon 7 to ~50 bp after start of exon 10. Note where exactly your exon borders are within the sequences.

    4. Go to primer3 here: http://primer3.ut.ee/ put in one of your sequences, use the Overlap Junction List to set restrictions where your primers can bind.

    Your primers should be

    1. Amplifying a product size of 100-200 bp

    2. At least one should span an exon junction:

    So for

    IIIb (exons 7, 8 and 10): One primer spans either the exon 7-8 or 8-10 junction (spanning the junction means that around 50% of the primer is in exon 7 and 50% in exon 8) and other primer in exon 10 (if 7-8 forward spanning primer) or exon 8 (if 8-10 spanning primer)

    IIIc (exons 7, 9 and 10) One primer spans either the exon 7-9 or 9-10 junction with other primer in exon 10 (can be same as for IIIb) or exon 9.

    Ideally you would use the IIIb exon 8 + 8-10 junction primer and IIIc exon 9 and 9-10 junction primer option.

    You need to play around and see what primer3 brings up. Then you need to BLAST the primers to check if they are specific.

    Do you now understand how the sequence would change depending on which splice isoform you want to target?

  • Suman Sharma added an answer in Energy Pricing:
    What is the best proxy for energy price in a country if the country's energy price is subsidized?

    What is the best proxy for energy price in a country if country's energy price is subsidized? Can Subsidized price be used in estimating energy demand function? 

    Suman Sharma

    if country's energy price is subsidized due to which factors this is happening? substitute products whose cost are rising then their price should be marked as proxy price to energy in market language.

  • Benni Koenig added an answer in Microscope:
    Is it possible to build a white light TIRF illumination system on your own?

    Hey everyone,

    I read a lot about the theory of TIRF microscopy by now and started wondering wether or not it is possible for those of us with small financial background to set up a white light objective based TIRF microscope with the epifluorescence Scope I am using at the moment?  Any experience  or publication suggestions? The illumination system is the special point I am struggeling with, since the non-collimated light of my Arc lamp needs to be somehow focused with a lens or be "thinned" with a opaque disk (or something similar) for being defined enough to get it a a steep angle to the back focal plane of my objective.

    Or maybe you tell me directly, forget it and buy one. Either way, I am very thankful for your answers!

    PS: A review I found, written by Axelrod (link added), stated that it is possible. Did anyone of you try this? Are there specialists for a Olympus IX-50 stage (creating a back focal plane with two lenses)?

    Benni Koenig

    Wow thank you guys for these very helpful answers!!!  I´ll try wether I can achive something with your tips, if so I will let you know! Maybe even if not, just to give other people the opportunity to not make my mistkaes :)

  • Nai-Kei Wong added an answer in Edema:
    Best treatment period for accute inflammation?
    • i'd like to start work on carrageenan induced paw edema i have been selected paw edema so could any one suggest a best treatment period for analysing protective effect of selected compound on paw edwma.
    Nai-Kei Wong

    hello, please see this and other methods papers:



    The kinetics is here:


    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: Several methods for measuring inflammation are available that rely on the parameters changing during inflammation. The most commonly used methods estimate the volume of edema formed. In this study, we present a novel method for measuring the volume of pathologically or artificially induced edema. In this model, a liquid column is placed on a balance. When an object is immersed, the liquid applies a force F to attempt its expulsion. Physically, F is the weight (W) of the volume of liquid displaced by that part of the object inserted into the liquid. A balance is used to measure this force (F=W).Therefore, the partial or entire volume of any object, for example, the inflamed hind paw of a rat, can be calculated thus, using the specific gravity of the immersion liquid, at equilibrium mass/specific gravity=volume (V). The extent of edema at time t (measured as V) will be V(t)-V(o). This method is easy to use, materials are of low cost and readily available. It is important that the rat paw (or any object whose volume is being measured) is kept from contacting the wall of the column containing the fluid whilst the value on the balance is read.
      Journal of Pharmacological and Toxicological Methods 02/2000; 43(1):11-4. DOI:10.1016/S1056-8719(00)00089-7
  • Mario Paris added an answer in Brand:
    Universal approach to a retail store is there any such existing design?

    I am a MA Design student at northumbria university, newcastle

    My design proposition for my dissertation is about an universal approach in a retail store. i am trying to research of such existing designs and few principles to be followed. Also my project aims to encourage and brand such approaches.


    Mario Paris

    Dear Nikhila,

    in my opinion, there are a new trend  that showed a change of approach in retail design. It is the adaptation of several brand images and principles to the place in design shops, and this process bring to a new kind of retail environment, where global imaginaries dialog with local traditions and specific features. The result is a sort of hibrid spaces, and it is very important not only the design of the shop, but also the insertion in a specific context and, sometime, the re-use of important spaces (as industrial-productive warehouses, etc.). At the same time there is other examples that mix innovative forms of retail and traditional ones (public markets, etc.). In my opinion an interesting case studies of this trend are the Eataly stores in Italy (Milan, Turin, Rome) and all around of world.

  • Philipp Otto added an answer in R:
    Anyone familiar with subgroup data on forest plots in R software?

    Hi im using R studio to perform meta-analysis to calculate pooled survival outcomes (eg 1 year OS). No IPD data.

    I have never coded before- so struggling quite a bit.

    I am unable to get subgroup data to show on forest plots.

    Ive used the bcg data example supplied by R software but no luck.

    I am not sure if

    1) I am using right formatting in excel: using individual cohorts to group similar studies and have just listed them- tried to use vectors to do sub group

    eg forest(tvsnt3, order="prec", subset=c(1:23, 24:29), tansf=transf.ilogit)

    I have also done separate meta analysis on the two subgroups- so if there is a way to 'join' the two forrest plots that would work.

    2) I am using the correct code format (as above)

    Can anyone help? I am really a beginner when it comes to R studio..

    thank you in advance

    Philipp Otto

    Have you checked the function forestplot() from the R-package rmeta? The function is quite flexible and you could implement the mean and variance of both subgroups separately within a list.

    It could be helpful, if you could post your R-Code. I'm not sure, whether it will help you, but also the tilde sign (~) could help you. At least, you could group your data by using the tilde sign regarding the function boxplot().

    For instance:

    x <- rnorm(29) # generates 29 random numbers
    subgroup <- c(rep(1, 23), rep(0, 6)) # generates a vector with 1 for the first 23 entries indicating that the first 23 items belong to your first group and 0 for the items 24 until 29
    boxplot(x ~ subgroup) # draws the boxplot for two subgroups

  • Nick Weston added an answer in Titanium:
    How do I measure the porosity of a titanium sample ?

    What is the best way to measure the porosity of a titanium sample without using X-rays ?

    Take slices of the samples and take surface porosity ?

  • Mohamed El Naschie added an answer in Foundations of Quantum Mechanics:
    How do we understand a conservation law (Noether's theorem) in quantum mechanics?

    In the classical mechanics Noether's theorem says that

    "if a system has a continuous symmetry property, then there are corresponding quantities whose values are conserved in time"

    As a simple particular case, a quantity A that doesn't depend on time explicitly, neither through other parameters on which it depends, i.e. dA/dt = 0, is a constant of motion.

    The question is what becomes of this law in quantum mechanics (QM)? Does it hold at all? And if it does, what is its meaning?

    The QM gives the following formula for the time derivative of an operator Ȃ:

    (1) dȂ/dt = ∂Ȃ/∂t + i/ħ (ĤȂ - ȂĤ),

    where Ĥ is the Hamiltonian of the system, and Ȃ is a Hermitic operator attached to an observable of the system.

    Assume now that Ȃ doesn't depend explicitly on time and commutes with Ĥ, therefore dȂ/dt = 0. How shall we understand this result? Does it mean that the value of the operator Ȃ is fixed during the system evolution, even if we don't measure it?

    Or, alternatively, does it mean that performing a measurement of Ȃ on identically prepared systems, we are bound to find the same value of Ȃ?

    In other words, in the QM, a quantity which is a constant of motion, possesses a value, and it is fixed in time, independently on whether we measure it or not? Or, alternatively, it takes a value only if we measure it, and the value is the same if we repeat the measurement on identically prepared systems?

    Mohamed El Naschie