Q&A

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  • Patrycja M.H. added an answer in Political Parties:
    Which research methods are the most suitable for studying changes in the ideologies of political parties?

    I want to study how the ideologies and rhetoric of far right parties in Poland have developed in the last 20 years due to Globalization processes. Which research methods would be the most suitable?

    Patrycja M.H. · İstanbul Bilgi Üniversitesi

    Thank you for all advices!

  • Sergio Antonio Muñoz Pinzón added an answer in CFRP:
    What are the main joining processes (and the fastest ones) for metal and Fiber reinforced plastics sheets?

    I'm testing a new process for joining metal sheets and Glass Fiber Reinforced Plastics (GFRP) as well as CarbonFibre Reinforced Plastics (CFRP)

    Sergio Antonio Muñoz Pinzón · Los Andes University (Colombia)

    you can try adhesives or mechanical joining

  • Sergio Antonio Muñoz Pinzón added an answer in Residual Stress:
    Modelling of Residual stress in case of arc welding in APDL?

    I am modelling residual stress in case of arc welding. I am not getting proper temperature profile. The main doubt I have is whether center of heat source should be on surface of base plate or on top of weld bead?

    I am using Element Birth - Death technique to model it.

    Sergio Antonio Muñoz Pinzón · Los Andes University (Colombia)

    heat source should be on the weld bead, I suggest first model a uniform heat source and then try a Goldak heat source

  • Sergio Antonio Muñoz Pinzón added an answer in Friction-Stir Welding:
    What could be a suitable material model for Friction Stir Welding of Polymer sheets?

    I'm dealing with friction stir spot welding of thermoplastic polymers such as PC: I've measured the plunging force and torque other than the temperature of the tool and that of the material at a reference point. I would like to develop a FE simulation of the process to better understand the material flow. Could a simply temperature dependent elast-plastic model be suitable for the purpose?

    Sergio Antonio Muñoz Pinzón · Los Andes University (Colombia)

    Elastic-plastic is not well suitable for this simulation, viscoplastic model could manage variations in viscosity and plasticity in polymer. Polymer doesn't melt at a specific temperature, some molecules melts first so you have a range of melting. In Polymer you can melt partially the polymer with FSW,

  • Jann Gilbert added an answer in Marine Biology:
    Can anyone identify this? Aborted foetus?

    Apparently washed up on a beach in Iluka, NSW, Australia.

    Jann Gilbert · ASR / EnTox / Southern Cross University

    Only other information I have is that it's around dinner plate size. A fisherman suggested a coffin ray. I've attached another pic of it turned over. 

  • Steingrimur Stefansson added an answer in Acetazolamide:
    What is the ideal solvent for Acetazolamide for intravenous injection in rats?

    I need to inject Acetazolamide intravenously (single dose at 21 mg/kg) in anesthetised rats, while maintaining a pH at a non-harmful level. 

    For my desired concentration of 20mg/ml, it does not dissolve in saline or 0.1M NaOH, and 1M NaOH is too alkaline (pH 11), despite good solubility.

    If I were to choose an intermediate strength NaOH, can HCl be used to lower the pH?

    Thanks.

    Steingrimur Stefansson · HeMemics Biotechnologies Inc.

    Hi Paula, you could try making a 50-100 mg/ml stock solution in DMSO and dilute it with rat serum albumin (5-10 mg/ml) for a working solution. 

  • Arfan Ali asked a question in CMC:
    How CMC and Chitosan treat as edible coats for fruits and vegetable?

    How they work as bi-layers for coating fruits?

  • Jackson Achankunju asked a question in Bioeconomics:
    Can any one please help on Bioeconomics of microalgal aquafeeds?

    Production  of aquafeeds from micoalgae has become an option to make  the  aquaculture more sustainable.Would any one like  to share reviews on Biology and economics of microalgal aquafeeds. 

  • Hazim Hashim Tahir added an answer in Economy:
    How does the rise in food prices affect the rate of inflation around the world?

    One effect of higher food prices in a given country is higher consumer price index (CPI) inflation.However, higher food prices affect people in different economies differently.
    The impact of rapidly rising food prices on CPI inflation is substantially larger in emerging market economies than advanced economies

    This effect tends to be much greater for countries that are 1) large net importers of food, and 2) where households spend a greater percentage of their income on food (meaning that they have a much larger weighting of food in their CPI basket).
    In short, higher food prices don't hurt everyone equally. Poorer, developing economies feel it much worse.

    Please, present your opinion.

    Very kind regards

    Hazim Hashim Tahir · Ministry of Science and Technology, Iraq

    Dear Colleagues,

    Good Day,

    Here is a very interesting paper entitled: "INFLATION IMPACT OF FOOD PRICES: CASE OF SERBIA"
       By :    Dejan Šoškić2
    Summary
    Food prices traditionally have an impact on inflation around the world. Movements in these prices are coming more from the supply side, then from the demand side. If treated as a supply shock, monetary policy should not react. However, food prices are part of headline inflation that is an official target for most central banks. Serbia conducts Inflation targeting and faces serious challenges with food price volatility. Food price volatility in Serbia hampers inflation forecasting, and may have a negative influence on inflationary expectations and public confidence in (i.e. credibility of) the Central bank, all of crucial importance for success of Inflation targeting. There are several important possible improvements that may decrease volatility of food prices but also limit negative impact of food price volatility on Consumer Price Index (CPI) as a measure of inflation. These improvements are very important for success of Inflation targeting in Serbia.

    please, see the complete attached paper 

  • Daniel Patón added an answer in TWINSPAN:
    Is there Twinspan analysis in R?

    Is there Twinspan (two way indicator species analysis) in R? I found cluster::diana
     DIvisive ANAlysis Clustering in R, a divisive hierarchical clustering method. Is it the same - under special conditions - as Twinspan?

    Daniel Patón · Universidad de Extremadura

    Hi,

    You can install a modified version of TWINSPAN. Instructions in this page:

    http://www.davidzeleny.net/anadat-r/doku.php/en:hier-divisive

    Also you can try other version of clustering methods in community ecology inside R such as the library FLEXCLUST or the Indicator Analysis (indval) of the library LABDSV.

    Good luck

  • Ravinder Jerath added an answer in Cognitive Systems:
    Is Chalmers' so-called "hard problem" in consciousness real?

    In his 2014 book "Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts" Stanislas Dehaene wrote "Chalmers, a philosopher of the University of Arizona, is famous for introducing a distinction between the easy and the hard problems. The easy problem of consciousness, he argues, consists in explaining the many functions of the brain: how do we recognize a face, a word, or a landscape? How do we extract information form the senses and use it to guide our behavior? How do we generate sentences to describe what we feel?

    “Although all these questions are associated with consciousness,” Chalmers argues, “they all concern the objective mechanisms of the cognitive system, and consequently, we have every reason to expect that continued work in cognitive psychology and neuroscience will answer them. By contrast the hard problem is the “question of how physical processes in the brain give rise to subjective experience … the way things feel for the subject. When we see for example, we experience visual sensations, such as that of vivid blue. Or think of the ineffable sound of a distant oboe, the agony of an intense pain, the sparkle of happiness or the meditative quality of a moment lost in thought … It is these phenomena that poses the real mystery of the mind”."

    Stanislas Dehaene's opinion is "that Chalmers swapped the labels: it is the “easy” problem that is hard, while the “hard” problem just seems hard because it engages ill-defined intuitions. Once our intuition is educated by cognitive neuroscience and computer simulations, Chalmers’ “hard problem” will evaporate".

    Personally, I agree with Stanislas Dehaene's opinion.

    Ravinder Jerath · Augusta Women's Center

    Graeme  your statement : 

    am more than ever, sure that your idea of a 3D space that includes non neural cells, is unsupportable. The thalamus is heavily involved in consciousness it is true, but this is because it is a major hub of sensory information, not because it is part of the consciousness mechanism directly.

                   Have you considered what you see internally as to what do you see when you close your eyes ? I will give you multiple choices and you can let me know.  

    a) Nothing

    b) black or dark space without borders

     3) you can imagine the sky around you . 

    Hopefully I would let you prove to yourself as to why do we have a 3 D default space within us and what does it do. I will handle  the question on thalamus after that. I would encourage anyone else to take this quiz and journey with me to see the view of self space from another angle. 

  • Denise Tolbert added an answer in Design Research:
    What professional organization do you associate with the phrase "Learning Design Research and Practice"?

    There are organizations that focus on training, educational research, performance design, etc..  Is there anyone in particular that you reference when thinking of learning design research and practice?

    Denise Tolbert · National University (California)

    Hi Camille:

    I would suggest AECT, ISTE, AERA.

  • Nabeel Ali Bakr asked a question in Peak Shift:
    How to explain that the residual stress can shift some xrd peaks in one direction, and other peaks in the opposite direction?

    This is may be due to the need to balance stress at grain boundaries, and satisfy constraints on the strain tensor (for example a tensile stress along one direction must be balanced by a compressive stress in the normal direction, so the direction of peak shift is often hkl dependent. Is there any reference related to this issue?

  • Joseph Olugbenga Odusanya added an answer in Coconuts:
    Is there an eficient method of coconut micropopagation that is reliable even to fruiting?

    I am aware that some efforts with somatic embryogenesis resulted in too many non fruit bearing trees, but I am hoping someone has better results to emulate

    Joseph Olugbenga Odusanya · Biocrops Biotechnology Limited

    Thanks

  • Steingrimur Stefansson added an answer in Cathepsin B:
    Are there any inhinitors of cathepsin B or S that do not inhibit trypsin?

    There are lots of cathepsin inhibitors, but does anyone know whether there are any which do not block trypsin activity?

    Alternatively, a trypsin inhibitor that does not block cathepsins would be just as good.

    Cheers

    Chris

    Steingrimur Stefansson · HeMemics Biotechnologies Inc.

    Hi Chris, can you use 1 um N-methyl maleimide to alkylate the active site Cys?

  • Zine Regainia added an answer in Thin Layer Chromatography :
    Why does the spot in TLC not move up?

    I was trying to checking the purity of my synthesized complex.

    I can't help but to notice there is luminescence in my TLC where the my compound was spotted. But then, the luminescence spot did not rise under DCM and not even hexane an cyclohexane.

    Why it did not moved up?

    how to seperate the compound from other?

    Please advise

    Thank you very much

    Zine Regainia · Badji Mokhtar - Annaba University

    You eluate your plate completely with the EDTA solution and dry it  at 110°C in an oven appropriate and you use the plate for the separation

  • Kevin F McCarthy asked a question in Embryology:
    Common neuroectodermal origin of human platelets and spinal dorsal horn?

    I know I read this in a paper detailing the rationale for work in the 1980s where platelet responses were used as model to study the effect of antidepressants and antipsychotics prior to more modern neuroscience techniques. 

    However, I cannot find an embryology reference that explicitly states this, unless I am misremembering what I originally read. Does anyone know of corroborating lines of enquiry or a reference to support why platelet models were used.

  • AlberTinka Murk added an answer in Fish:
    Does anyone recognise this small jelly fish?

    Does anyone recognise this small jelly fish - like creature ?

    I found 2 of them 1 m deep in (salt water) canal in Curacao.

    Tinka

    AlberTinka Murk · Wageningen University

    Attached a magnified view. I am sorry the quality is not better. Perhaps it could be some kind of migrating juvenile life form of something? 

  • Blake A. Gentry added an answer in Cross-Cultural Comparison:
    What are cross-cultural differences in terms of assessment and evaluation practices in educational settings?

    cultural differences with respect to evaluation and testing.

    Blake A. Gentry · The University of Arizona

    To Rahimi, To Daniela and Sergio,


    The issue of assessment is complex and I appreciate the perspectives offered in response to Rahimi's original question. Cross cultural differences in the use of assessment and evaluation practices appear to diminish with the increased use of standardized assessment and evaluation frameworks in the US; that is a logical result of standardization. How that plays out in other countries (Brazil, for example) may be instructive to the US, however we do not have a centralized secretary of education, so it is in the experimental phase in terms of national policy, which is a course that other complex issues have taken in the formation of public policy in the US.
    That can allow for pilot projects with results particular to some settings but not replicable elsewhere to be excluded, and theoretically to only include “best practices” in national legislation. My main point is that minorities' views and roles in the nation are rarely included in this scheme. Social alienation follows. This is likely much less a concern (yet) in developing countries where multi-cultural relevance is less important than anti-poverty measures and the need for basic education and some standards. In that sense these systems are not comparable; they are at different evolutionary stages in education policy (but more evolved does not imply - better). I haved worked on curriculum and testing of adult health promoters in rural Guatemala for 20 years; adults with only a primary level of education; so I am for improved education access and quality in general. This year we are now training new students whose ave. educ. level is secondary, and their skill levels are higher, so educational access and quality matter.


    In my experience, I think that assessment for individual students and even school performance is useful especially when done using some student portfolio work in combination with empirically derived sets of knowledge, and just not mass multiple choice testing. I have administered over 2,000 such tests in US summer employment programs to "level" students" in federally funded urban municipal programs, so I have seen where well intented use of tests starts to translate into economic decisions about who is enrolled in non-educational purposes, and it does not equitably perform that task.


    The relevance of curriculum to testing was not raised by Rahimi, but it becomes an issue after the first generation of testing demonstrates, unfortunately, persistent gaps between ethnic groups, gaps  which overlap with economic disparities.  Again this may be an issue more in "advanced" development countries, but it is a forewarning of what can happen. Others may disagree with my premise of tying education outcomes to an equitable economic outcome, given meritocracy is the popular and dominant US business model applied to education.


    The political sloganeering in the US in that regard promises that education "lifts all boats". This has proven to be an economic fallacy. The economic advantages of education appear to be tied with persistent socio-economic discrimination. The uprising of the African American community in the US currently - though related to police violence -is a case in point. Low graduation rates for African Americans mirror higher than average unemployment rates and their incarceration rates are the final measure of that false premise. Enclaves of Arab youth in Paris is another example.


    In short, I think the use of assessment and evaluation (I am an evaluator of public programs) can be harmful if the state's agenda is to perpetuate or strengthen a stratified society with highly skilled and low skilled individuals, or even if it maintains an agenda of "equal opportunity" which is a liberal label for market driven economic development (meritocracy only). Alternatively, assessment and eval. Can be beneficial if the state plans education to provide not only an intelligentsia, but a skilled workforce that contributes economically and receives some social assistance for its contribution to productive economic activity. The $15 per hour campaign being waged in the US for service workers is part of that counter-agenda. Secondary school counselors regularly tell students that they need to graduate in order to enter the job market. Few skills learned in those schools are needed in the service sector except for oral communication skills if we are honest about that match –up.


    A counter intuitive example of the first approach is the "dot.com" bust in the United States in the early 1980s. It demonstrates what can happen to even highly specialized and skilled workers. Universities rushed to produce computer programmers for a fledgling industry (high tech in Silicon Valley, California), which had a knock on effect of demand for higher math standards in secondary schools. When the unregulated industry crashed, and tens of thousands of highly trained computer engineers were dismissed en masse by companies like Microsoft, a peculiar legacy arose.


    Within five years, the industry leaders and their political allies were calling for increasing quotas for the importation of tech workers from abroad -because the education system was not producing enough computer engineers! The entire education system (primary through college) was highly chastised by that industry for being international laggards, etc. in this regard. The companies complained about the burden of training costs if not allowed to import tech workers from abroad.  That leads to brain drain for the developing countries, and fabulous profits for such corporations. Any teacher understands what that “burden” is all about, it’s called teaching and the resources it takes to successfully teach. Higher math skills can be a good thing, but the premise that they lead to better employment is negatively conditional to unregulated markets - in this case.


    I am glad to hear that in Belo Horizonte that socio-economic indicators also govern how schools are assessed. The problem becomes what happens when those students attempt to compete for jobs in markets where that is disregarded. A homogenous workforce is easier to manage; a multi-cultural one takes more effort. Educators know empirically that bilingual students for example, when given similar levels of education, outperform monolinguals due to skills acquisition in learning two languages. In homogeneous monolingual workforces those skills are often disregarded. There is a limit obviously as to what the institution of education can influence in society, so the goals for education should be debated. The direct relationship between culture and assessment begins in curriculum, not in assessment. Once the curriculum is exclusionary, assessment is, on a macro level a measure of how well students fit the profile created by the socio-cultural outlook of the curriculum writers. I do not think this is purposeful on the local level, but at the level of states/provinces and national testing regimes, it has a direct effect on student success. Brazilian educator Paulo Freire intuitively corrected for this by pioneering a method for social analysis that diminishes such exclusion. Skills acquisition and knowledge acquisition however go beyond social analysis and everyone in society needs them for productive purposes. Who gets them is what is at stake.

    The policy question becomes, how do we create curriculum that acknowledges and expands on local knowledge, and then how can we hold assessment methods accountable?  Assessment and evaluation can be used to improve knowledge, but it can also be a Trojan Horse in the hands of the state to increase gaps in socio-economic standing; and that is where we appear to be headed in the US.


    I offer an additional post that exemplifies an alternative experience of curriculum and testing in Guatemala in the NGO sector, not in public schools.

  • Michael Patriksson added an answer in Traffic Simulation:
    I need some information about traffic simulation methods,could anyone help me?

    i need some information about traffic simulation methods or algorithm,could anyone help me?

    Michael Patriksson · Chalmers University of Technology

    Here is a link to a book concentrating on traffic simulation software:

    http://link.springer.com/book/10.1007%2F978-1-4419-6142-6 

    I know several of the authors, and it appears to be a solid book.

    Here is another - more of a text book, and it also looks solid:

    http://traffic-flow-dynamics.org/about.shtml

  • Oscar Crespo-Salvador added an answer in Bradford Assay:
    Am I adding too much chromatin if I get no signal differences in my ChIPqPCR ?

    Hello, in my PhD thesis I have to use ChIPqPCR to study the differences in plant's chromatin (control vs infected). To do so, I use some antibodys that bound to widely recognised histone modifications (bouth activators and repressors) besides the unmodified histone as a positive control.

    I have done several experiments and, in each one of them I have obtained very good signal (% of INPUT and fold enrichment). The problem is that I haven't seen any difference with any antibody (with and without relativization to a constitutive and/or the unmodified histone).
    All samples have been previously tested by RTqPCR with positive results in the problem genes (later used in ChIP). I have used as a negative control an irrelevant antibody and no antibody, with similar results (no signal).

    My theory is that I have been using too much chromatin as a consequence of my way to measure it:

    I took a chromatin aliquot, decrosslink it, extract the DNA and measure it with nanodrop, calculating later the concentration of potential DNA (in µg/µL) of my chromatin.
    With this information I add the amount of the equivalent to 25 µg of DNA per inmunoprecipitation (the amount recommended in the dynabeads protocols).
    Normaly a use 50 µL of dynabeads per IP an 0,1 µg of antibody per µg of DNA.
    I think that if I have been using too much chromatin, the antibodys or the magnetic dynabeads (the antibodies probably) get saturated with the target protein, not allowing me to see differences between control and problem.

    So, I have been reading similar problems and I noticed that the common method of chromatin measuring is the Bradford assay. In general the papers I read don't delve into this topic and in my lab they teach me to measure the chromatin directly (making dilutions obviously) with nanodrop (using ODs at 260 nm and additionally extracting the DNA and measuring it, expecting an approximated quantity of 15 µg/OD, (which is, more or less, which usually get).


    Am I measuring the concentration in a correct way?
    Do I put too much chromatin?
    Does it make sense my "too much chromatin" theory?
    What is the relative amount of antibody do you use (respect to dynabeads and chromatin)?

    Thank you very much and of course any help would be appreciated

    Oscar Crespo-Salvador · University of Valencia

    Thank you all for your answers and suggestions, sorry for the delay I'm on my vacation and I can hardly write in English...
    I'm going to reply everyone in order:


    Ales, I already use column based purifications although I had all these problems at the beginning of my thesis.

    Shreyas, I don't understand why the absence of background signal indicates that more chromatin can be added, I think that if the incubation and washing buffers are stringent enough; the chromatin amount could be irrelevant.
    I dilute chromatin always10 times precisely to avoid the negative effects of SDS in IP (lowing its concentration from 1% to 0,1%), the incubation buffer have triton-100 at 1%. All my buffers are very similar to the ones I saw in others works.

    Rushita, when I have my DNA prepared for PCR, normally I cannot properly determine its concentration (I guess it is too low). So, I always resuspend in 100 uL and use a final concentration of 4% (approx 0,4 uL per reaction of 10uL). With this parameters, my Cps values vary between 25 and 29.

    Hasan, my chromatin dilution factor is limited by the maximum dilution factor of magnetic protein G dynabeads (10 times according to Invitrogen), so using 50 uL, my top volume would be around 500uL, I don't know if this top dilution issue is very important, I just read it in the web protocol. Is for example the cause I don't just put 1mL in every IP.
    My oligos are designed normally for a 70-150 bp amplicon although sometimes I use larger, until 300 (usually oligos successfully used from other works).
    I really really hope you are rigth about Histone modifications, I am thinking to low from "my" 25 ug, to 5 ug (1/10) will you recomend me more dilution according to my results (more than 1/10 I mean)?

    Miguel, is interesting your point, because I have been trying to calculate what is the "real" limit of AntiBody that beads can attach; according to Invitrogen's web, 0.25-0.3ug of Antibody/uL of dynabeads is the capacity. Usually people put approx 1-10uL (I will asume 5) of antibody per IP and the AB concentration is usually 1 ug/uL.... So, using 50uL of dynabeads and 5uL of antibody, the used binding capacity of the beads is only 33-40% (0,1ug of antibody/uL of dynabeads).
    In summary, I thinks that I am using an excess of beads, and my limiting factor is the antibody.
    About nanodriop, how do you measure the chromatin, directly, extracting the DNA..? With what absorbance do you read?

    Alexander, thank you very much for your advice about denaturing chromatin. Out of curiosity, why you do not measure directly a chromatin dilution?
    My problem, besides not getting differences between samples is that with my current conditions I do not have enough chromatin to put the same quantity that you. (as maximum I get 200 ug with a starting material of 3g)
    The qPCR DNA quantity is the one I said to Rushita.

    Carmelo, as I said to Rushita and Alexander, I use a fixed elution volume and measure the DNA for the qPCR as a % of that. For measuring the DNA I denature and decrosslinking by incubating ON at 65ºC with 0,2M NaCl; then I use a column kit.
    Thank you for the info about picogreen, I didn't know it and may be extremely useful.

    Suvendu, I'm worry about the variation in the % of input recovery, the 50% data, comes from my first successful IP in wich I tried two different concentration of AB anti H3 0,04 and 0,2 (ug AB/ug chromatin), the fist one gives me a mean of 21% and the second 37%. So, with 5 times more AB, I got 2 times more signal. What would be the explanation?

    Jaclyn, my species is Arabidopsis thaliana but I have some RTqPCR confirmed inactivated genes and, I already use just that antibody but the results are exactly the same as with the other AB... I made some modifications (Making only one LiCl wash.) with the washes because with the last I lose some dynabeads.
    What stringency conditions do you use?


    I think that's all, again thank you very much.

  • Pallavi Dubey added an answer in Plant Extracts:
    Method for tannin removal.

    Is it possible that tannin might get extracted during an alkali extraction of a plant material? What is the best method of removal of tannin from an alkali plant extract?

    Pallavi Dubey · Forest Research Institute Dehradun

    Apart from lead acetate method, a method for the complete removal of the tannin.

  • Felix Ladstätter added an answer in Basic Statistical Analysis:
    How do I normalize data between 0 and 1 and highest frequency at the extreme ends?

    I have millions record in quarter, data in between 0 to 1. Bottom 5% contains 7% data and top 5% contains 84% data i.e. very high count at zero and  one. Is there any way to normalize it, because I am trying to check what % of data fall within confidence interval if we draw samples of different sizes.

    Felix Ladstätter · Instituto de Empresa SL

    Here is an interesting article about data transformation

  • Michael B LoMonaco added an answer in Fungal Infection:
    My cell line U87MG is getting detached after splitting, what could be the reason?

    few weeks back there was fungal infection in some of my petridishes. So, I thoroughly clened the incubator using bleach and rectified alcohol, revived fresh stocks, prepared everything fresh and started using sodium azide in the humidity pan 1g/L autoclaved water (earlier I used to use copper sulphate 1g/L). Now, the infection has dissappeared but my cells are dettaching after the first splitting I do after stock revival. what could be the reason for it.

    Michael B LoMonaco · University Center Rochester

    Himanshi

    Let's assume your incubator is clean.  I am unfamiliar with your cell line. If you are using a bicarbonate pH buffering system, it is critical that the CO2 in the incubator "matches" your growth media. BNN's suggestions are correct.  The best international journals require cell line confirmation/documentation.  Reacquire your cells from ATCC or an equivalent scource.

    Michael

  • Vitalii Mokin added an answer in Water Management:
    Does anyone have any references related to water distribution modeling and management?

    i need references  for water distribution modelling

    Vitalii Mokin · Vinnytsia National Technical University

    See my book (Swedish and Ukrainian).

    DOI: 10.13140/2.1.1707.2325

    (Web of Science, Thomson Reuters).

  • Artur Braun added an answer in Racism:
    Have you encountered racism in textbooks? How should we cope with this issue? What are the consequences of such an ideological dissemination?

    Racism and discrimination in curricula and textbooks. Causes and consequences.

    Artur Braun · Empa - Swiss Federal Laboratories for Materials Science and Technology

    I know a very impressive example in a middle school math textbook from the 1940s in Germany. It pictured in black ink a crippled looking family with 4 children, depicting antisocial part of population, and a family with 2 children only, sketched only in lines with empty space (= no black ink filled). The question was how the family with 4 children would spread with future offspring.

    So, with such material children in Germany were indoctrinated in the NS times. Clearly, when an author writes something, he/she may have a particular message in mind. Newspapers, bloggs textbooks, schoolbooks, reports. Even when we scientists are supposed to transports facts only in our publication, we are not free of bias.

    In your topic you ask for racial bias or maybe even racial intent and agenda. There may be situations where authors or publishers publish content while being simply ignorant. Another thing is when they have a clearcut political or philosophical racist agenda.

    In all these cases I would say it is up to the individual how to respond to that, how to deal with this. After all, would you want to counter a racist indoctrination with an antiracism indoctrination? People like to have "choice".

    From the scientific perspective the best way is - though I may be wrong here and I appreciate finding here a platform with an interested individual bringing up this topic for discussion and discourse - best way is to make your own experience by dealing and engaging with different "races" people and then talk about it and share your experience (Aufklärung in its modern and ancient meaning). Now I am pretty sure you have done so already without even thinking the racism question.

    So your question in my opinion falls into the category of civic responsibility. I know not of any other book right now other than the one I mentioned in the beginning. If we encounter a racist claim or item in a textbook, if we encounter this in class we may bring it up immediately in class and say "now I think this may be a racist statement. Why is this in this book?"  And you may send a letter or email to the author/s or publisher of the book and let them know how you feel about this racial statement in the book.

    After all, we humans are typically ignorant and maybe just were not aware of a faulty thing when we wrote something.

    And we have to realize there may be societies where racism is part of society. Not so long time ago it was the official line by Apartheid in South Africa.

    Unofficially, racism (or xenophobia, which is not racism per se) is a daily encounter all over the world, still.

    Speaking up is the first step for creating awareness.

  • Jonas Nyman added an answer in Cell Culture Techniques:
    Can someone help with the identification of a contaminant in a tissue culture lab?

    Dear all

    We've had a major problem with contamination in our tissue culture lab. Attached are the microscopy pics of media left inside microbiological hoods after cleaning... expert opinion needed please!

    We've also swabbed everywhere (hoods, incubator, bench, floor) onto LB broth agars, but nothing have grown thus far (3 days post cleaning).

    Help!

    Huzaimi

    Jonas Nyman · University of Southampton

    It's crystals. It must be some insoluble salt that has precipitated.

    The solution is to always mix nutrient media when it's cold. Never autoclave salt solutions, salts should be sterile filtered and added separately to autoclaved medium when it has cooled.

  • Bruce Weaver added an answer in Linear Regression:
    How can I check affect of moderating variable in regression analysis?

    I have three IV one DV and three moderating variables i.e. gender, age  and experience.  I have applied linear regression for checking the affect of IV on DV. 

    My hypotheses for moderating variables are to check the moderating affect of gender/age/experience on IV and DV relation.

     I have applied linear regression to check the effect of moderating variable gender.  Should I need to create dummy variables for the age and experience (as they have more than two categories)? Or  can I process it in same way as gender variable with two categories?

    Bruce Weaver · Lakehead University Thunder Bay Campus

    Gender: use 0-1 coding and treat as continuous.

    Age: Categorizing continuous variables is usually a bad idea. It throws away information, uses up degrees of freedom, imposes step-functions where they probably don't make sense, and lowers power. So if you have people's actual ages, you should analyze age as a continuous variable. It's okay to analyze age-category in exploratory analyses to determine the shape of the functional relationship between Age and Y. But having determined the shape of that relationship, you should then use actual age rather than age category (if you have it). If necessary, include appropriate polynomial terms (e.g., include both Age and Age2 if the functional relationship is U (or inverted U) shaped.

    Experience: How many categories are there?

    As others have suggested, if you are going to use the REGRESSION procedure, you'll need to compute sets of indicator variables for categorical predictors, and then products of those indicators with the IVs. For a categorical variable with k levels, I usually compute all k indicators (see SPSS syntax example below), but of course you must omit one of those indicators.

    * Generate indicator variables for Experience.
    * I'll assume 5 Experience categories--change 5 to the actual number.
    * I assume your original variable is called Experience.
    DO REPEAT E = Exp1 to Exp5 / # = 1 to 5.
    - COMPUTE E = Experience EQ #.
    END REPEAT.
    FORMATS Exp1 to Exp5 (F1).
    * Check that indicators are correct.
    CROSSTABS Experience by Exp1 to Exp5.

    If you are using the REGRESSION procedure, I would suggest that you use /METHOD = TEST (rather than the default ENTER). TEST allows you to specify groups of variables for which you would like to have multiple df test. See the Command Syntax Reference manual for more details (and an example). In your case, you would want a k-1 df test for any categorical variable, or interaction involving that categorical variable.

    Finally, another option is to use UNIANOVA (Analyze > General Linear Model > Univariate) rather than REGRESSION. It lacks some of the features present in REGRESION, but removes the need to compute your own indicator variables. Continuous predictor variables can be entered in the Covariates box, and categorical variables in the Fixed Factors box. All needed indicators are computed internally. You can also specify which product terms you want to include (on the /DESIGN line in the syntax). You can also ask for a table of parameter estimates (i.e., regression coefficients) to be included in the output.

    HTH.

  • Sungseok Lee added an answer in Sus scrofa:
    Can anyone suggest a good internal control amplification (IAC) for qPCR?

    I m working with PCV2 detection in SERUM of pigs (sus scrofa).

    I need to know the vality of false positive or false negative results of my samples, and the integrity of my DNA samples

    I m using taqman probe, 

    There is a lots of old information and a couldn't find the good internal control amplification for my situation.

    ex. ACTB, GAPDH, 18S

    Sungseok Lee · Virginia Polytechnic Institute and State University

    GAPDH might be the most fitable one for you. I've used GAPDH as internal control for DNA extracted from pig serum just like you and it worked well. But I used SYBR green at that time. there is 18s rRNA kit from applied biosystem and it is for probe type qPCR. It was tagged woth VIC and working very well.