Q&A

ResearchGate Q&A lets scientists and researchers exchange questions and answers relating to their research expertise, including areas such as techniques and methodologies.

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What is the solution of a first-order vector ODE involving a cross product?

I mean, what is the solution to the vector first-order ODE (or in which book or site can I find it?):

\vec \omega \times \frac {d}{dt} \vec r = \vec g

ω, g are constant coefficient, not dependent on the variable t.
I could call it Coriolis equation, sinice the first member is half of a Coriolis field.
I know that if k is the unit vector of ω, j the u.v. of g, i is defined jxk:

\frac {d}{dt} \vec r (t) = \frac {|\vec g|}{|\vec \omega|} \hat i(t) + v_b(t) \hat k(t)

But then how to integrate it?

\vec r (t) = ?

Can I pivot on the Poisson relations even if the problem is not apparently the standard rotation one?
Can I assume as a choice on frame of reference:

\frac {d}{dt} \vec r (t) =? \, \vec \omega \times \vec r

Matteo Lanfranchi · Politecnico di Torino

Demetris it is definely funny that a problem originating from Fitzpatrick, Plasma Physics, chp. 2 comes back to Fitzpatrick, especially because I posed the problem in an analytical form such that the physical origin was not even cited, but also hidden I think. Or maybe this kind of equation arises only in guiding center motion? Anyway, I am reading carefully Fitzpatrick the 2nd... :-) Thank you!

What are the challenges in implementing sustainability in the construction industry sector?
The construction industry sector has been identified as a slow adopter of sustainability. What are some of the challenges specific to the construction industry that is hampering its progress? Are there any papers or evidence which discusses about this in the literature?
Ramana Koti · Lord, Aeck & Sargent Inc.

At least for architects' and designers' perceptions, here is what a recent survey of sustainable design leaders in the US indicated:

Top challenge: Inertia/habits/established patterns

Runners up: Lack of commitment from clients, first cost of projects, insufficiently integrated design, schedule/time.

See resources of the attached publication.

• Does anyone have ‘cotton-strip’ decomposition data that they would like to share for a large comparative study?

I'm working on a meta-analysis of factors influencing cotton-strip degradation in streams and rivers and thus am collating a large database in collaboration with Dr Scott Tiegs from the USA and Dr Guy Woodward in the UK. I already have a lot of data from various sources, however, the more data I can use the better. Does anyone have any cotton-strip data (i.e., tensile strength loss) and if possible, congruent litter breakdown and physicochemical data that they wouldn't mind sharing for our study? If used, your contribution will be fully cited.

Pablo Rodriguez-Lozano · University of Barcelona

Hey Francis! Probably Annika Wangenhoff or someone else from Christoph Matthaei group have some NZ data. (Maybe you have already talked to them). In Spain, I don't know people working with cotton-stips, just leaves or wood sticks. Good luck with your cool study!

What is the nutritional recommendation for the child with autism and /or Down syndrome in early developmental stages?

There are different types of chronic care implemented for the child with autism and Down syndrome, but what is the nutritional component of care in early developmental stages for these individuals.

Dick Sobsey · University of Alberta

There have been numerous recommendations for dietary treatment of autism, suggesting that eliminating dairy, gluten, food additives, or various allergens. Some of these things may help some kids with autism, but for the most part, the nutritional needs are the same as for any child of the same age, unless a specific food sensitivity is clearly identified.

What is the possible option to convert agro residues in to energy ?

Agro residues may be seed cake, husk, shell or straw.

K. Sudhakar · Maulana Azad National Institute of Technology, Bhopal

Briquettes and pellets is one of the best way of converting agro residues into useful solid biofuel.

• Why am I getting different measurements of particle size by dynamic light scattering, laser diffractometry and TEM?

I have measured some particles I prepared by different techniques, and I have obtained very different results with each one. They are around 1500 nm when used laser diffractometry, 500 nm when I used DLS, and tiny (aroun 30nm but very very polydisperse) when I visualized them under TEM. They had trehalose for cryopreservation. Can anyone find an explanation for this? What data should I trust?

Thank you!

Cesar Antonio Ramirez-Sarmiento · University of Chile

Hi Aiala,

I've used the same DLS a few times and I think you may have gotten some information about the polydispersity of your sample, and the most abundant species in your sample according to their particle size, on the Malvern Zetaseizer DLS you were using. This should help you to determine the discrepancies in your results compared to the TEM. Also, you might want to try to dilute your samples and analyze again on the DLS in order to see if this is a concentration-dependent pattern (which it should). But I agree with Sebastian about the TEM results being the most trustworthy.
I'm far from being an expert but I hope it helps out.

What is the best research Methodology for a Critical Information Infrastructure Protection Survey?

What is the best research Methodology for a Critical Information Infrastructure  Protection Survey in the banking sector.

Andrzej Bialas · Institute of Innovative Technologies EMAG in Katowice, University of Economics in Katowice

We start CIRAS project. It is focused rather on energy, sector may be ob water providers. We does not consider finacial sector due to thebudget restrictions.

Generally such issues as interdependecies, escalatopns, cascading effest are alway s important. Bow-tie risk assesment is important

Regards

Andrzej

• Where is the intelligence in AI?

Like many others, I am very enthusiastic about artificial intelligence, but the more I studied the AI, the less intelligence I found in it. What I found was classification, pattern recognition, and regression. Is there any hope for real AI to be developed in the future? Is it still correct to call AI AI?

Ernesto Araujo · Faculdade Ciências Médicas (FCM-MG)

Dear Fereydoun,

this topic is so extensive that we could approach it for days. Briefly, there is no consensus about what intelligence is, much less how to represent it on the machines (computers). This issue became even more complicated after Decartes separated mind from the brain (the mind-body problem). There is a fierce dispute as to whether the intelligence is in each place, yielding the called ABC of intelligence. The set Artificial intelligence, Biological Intelligence, Computer Intelligence will give you a top-down or bottom-up models (also mathematical and computational). According to your area of ​​interest or training, you can follow by psychology, philosophy, computing etc. If you belong to the latter worth focusing on artificial intelligence (as a discipline), computational intelligence, softcomputing, bio-inspired systems, just to name a few.

Herein there is one of the feasible interpretation upon what intelligence is that could interest you as an initial reading. It encompass philosophical, epidemiological, etymological, artificial intelligence,  computational intelligence, softcomputing, robotics in just one concern.

How to separate the cyclodextrin from the complex with peptide?

I was using C-18 high pressure column for peptide separation using

• Mobile phase A: Methanol, 0.5% Formic Acid
• Mobile phase B: Water

with a gradient up to 40% of water in 35 min. The complex is cyclodextrin + peptide. I observed a very significant peak for cyclodextrin 232nm at 40min while washing with Methanol. I had no luck with a single-phase Methanol run (wide and inconsistent peaks).

Hugues Preud'homme · Qatar Foundation

Dear Alicja,

I think your pH is bit low at 0.5% of formic acid, try to switch to high buffering solution at pH of about 4.8.

Best regards

Hugues

• Is there a strong possibility that bacterial vaginosis predisposes to cervical intraepithelial neoplasia?

More than ten percent of the female population has been involved worldwide in bacterial vaginosis, but the cervical cancer is considerably less frequent. So the hypothesis that bacterial vaginosis predisposes to cervical intraepithelial neoplasia does not have a strong possibility according to the statistical data mentioned above.

Are we going to see inheritance IT infrastructure and its setting vanish within the next 5 years?

Eliminating the need of having servers, meanwhile the new software would be ready to run on cloud available online, not to mention the expansion in applications and increase in complexity and scalability. All of these changes I suggest would mean the vanishing of IT infrastructure as we know it.

James J Coyle · Iowa State University

There will always be needs which require private servers/clouds.

The main question for most applications is not technical, but economic.

Of course there will be servers, since that is what a cloud runs on. Now if you are asking whether all software will be cloud aware, then that is an economic issue.  Can software companies make money that way?

For years, we had mainframe based computing, where all apps ran on a standard platform.  The apps were very expensive, because the software companies had only a few customers to charge.

Then came workstations and PC, where there was a broader base, and $100 per single user app became very common. If an economic model develops where the cloud suppliers can purchase and rent out apps, or where the cloud provider is like a grocery store or a consignment house, the going all cloud would be viable. The last would be similar to a utility grid, where you purchase your electricity and get sent a bill. I suspect large corporations and universities would set up their own cloud for business integrity/continuity and security reasons. Would you think the IRS will run on a non-private cloud, or air-traffic control? • Amar Singh added an answer in HEK293 Cells: Why don’t I see a band of my His-tagged protein in western blots? I have constructed a pcDNA3 vector with a gene of interest. The DNA sequence of my construct is confirmed and His tag is in frame with my protein. However, when I transfect HEK293 cells with my construct, I can't get a His tag signal in my sample using several different anti-His antibodies. However, the positive control works. Unfortunately the antibody against my protein is not specific so the only way for me to make sure that the protein is expressed is via western blotting or immunofluorescence. My protein is about 60kDa. I don’t know if the problem is with the transfection? Any suggestions would be appreciated. Thanks for your help! Amar Singh · Stanford Affiliated VA Palo Alto Health Care System I also have same problem, if some body knows the answer please let us know. Thanks, • What micro-algae species would you feed as a food-supplement to calves and why? For a project we're planning to grow different algae-species to add as a food-supplement to the (formulated) milk for calves. What species would you choose and why? Thank you in advance for all you tips and ideas. Alaa Kareem Niamah · University of Basrah please look you in attach file • Cody Kime added an answer in Affinity Purification: How do you do affinity-purification of antibodies from serum or plasma? In my previous lab we affinity-purified IgG antibodies using serum and protein G beads. If we had plasma only, we clotted the plasma (by calcium and/or bovine thrombine) to get 'serum', and then did affinity-purification (AP). Would it be possible to do AP just with plasma right away (I did find some publications doing just that at pubmed)? In other words: Do the fibrinogens in plasma actually interfere with AP of antibodies? Looking forward to your responses! Cody Kime · J. David Gladstone Institutes If you're using Serum based antibody production, you can use Mellon Gel to remove undesired proteins to start, and then run a Protein G column afterward for a tight cleanup. http://www.piercenet.com/product/melon-gel-igg-purification-kits Beware, though. In my experience with the mellon Gel, the Heavy chain of my Rat-based antibody was being stripped away. It was very strange and I had to run a blot to prove it. I think the gel is compatible with some, but not all antibody types. I, personally, prefer to adapt the line to serum free suspension cultures, optimize harvest (which is after the cells have saturated the media and are dying with about 40% of cells 'dead'). From there, I spin out cell debris, filter with 0.2uM filters, and then move to Protein G column purification via FPLC (HPLC). I have a great adaptation protocol and purification protocol that beat AbCam's quality (and yielded about$300k in antibody).

The use of the picture exchange communication system (PECS) in supporting the teaching and learning of children with ASD.

I am currently undertaking research for my dissertation in primary education, and am looking for research that concerns the use of PECS in supporting the teaching and learning of children with ASD.

Specifically, I am looking for any reareach that explores the behavioural impact this has on engagement and participation in learning.

I would be be very great full if anyone could help! :)

Dick Sobsey · University of Alberta

In doing research, it is important to differentiate between between the formal PECS system and its many components. For example, Many individuals with autism and other developmental disabilities use picture symbols and often use them on manipulable tiles but not necessarily with the extensive prompting and shaping systems that are part of the PECS program. PECS is specific product that combines a number of well-established behavioral communication approaches, most of which existed before PECS and some new ones. So you need to decide whether you are researching the specific product or the components.

What kind of statistical analysis should be carried out for RT-qPCR data, which has been used to validate microarray data?

Suppose I have around 20 differentially expressed genes for which RT-qPCR data has been generated, and the samples are a wild-type plant and a knock-out mutant.

Which statistical analysis should be done?

In several papers, people have used one-way ANOVA; in others, they just report the correlation between microarray and RT-qPCR data.

David Stiles · National Institutes of Health, Clinical Center

Jochen,

dCT and LFC are not the same thing!  The first delta Ct value is calculated by subtracting the Ct value of the gene of interest minus the Ct value of the "housekeep" or reference gene.  This is for normalization purposes only.  Your statement that microarray results are provided by themselves as log fold change values is true but for a parametric statistical test (ex. t-test, ANOVA and ANCOVA) the individual transcript's microarray log2 intensity values are used and never log fold change (i.e.  log2 ratio).  The fold change (i.e ratio) is obtain by taking the mean of the intensity values of the experiment group and dividing it by the mean of the intensity values of the control group.

In your last paragraph your state: "The distribution of the fold-changes (2^dCT and 2^LFC) is log-normal, the distribution of the log fold-changes (dCT and LFC) is normal."  This is completely backwards do you realize that Ct values are logarithmic values as they are calculated and exported by computer running any real-time PCR machine?  Simply subtracting Ct log values to obtain a dCt does not change this.  Fluorescent intensity generated by a microarray scanner and recorded by computer are linear intensity values.

• If the positronium minimum radius is equal to the Bohr radius, does that mean our space is quantized?

Positronium annihilates even before the lectron and positron meet. Does that mean that our space is quantized (like it is in holographic plates in form of bit)?

Regards,

Bhushan Poojary.

Bhushan Bhoja Poojary · NIMS University

Hello James,

You will find as per spin of of both electron and positron ground state of postronium varies.

"The ground state of positronium, like that of hydrogen, has two possible configurations depending on the relative orientations of the spins of the electron and the positron."

Regards,

Bhushan Poojary

Why is radiation pressure force non-conservative?

Due to the non-conservative nature of radiation pressure force, it can be used for the cooling of atomic motion.

Muhammad Anwar · National Institute of Lasers & Optronics

Stephen! Your arguments are just mathematical results and therefore susceptible to be irrelevant and wrong. You do not imagin the physics. I recommend you to read Cohen-Tannoudji, his papers and books. Good Luck..

• Currently, what is the level of research in the field of intelegents nanowires applied to cancer diagnosis at the molecular ?

It has been shown that the characteristics of the presence of cancer in a patient molecular markers could be detected in a single drop of blood by means of new types of sensors developed from nanowire arrays.
This exceptional sensitivity is accompanied by an excellent selectivity which should help diagnose the type of cancer with the offending speed today still inaccessible to clinicians.
This is achieved by attaching the nanowires antibodies specific for certain molecular markers of cancer, and detecting changes induced conductivity in nanowires by capturing these markers.

How to countries manage billboards using open source web GIS for optimal revenue collection?

How do countries manage billboards in in order to collect revenue and keep track of maintenance requirements?

If one advert is pulled down, how do possible clients know of its availability?

Are there research papers written on this which incorporate web GIS?

Peter Mwangi Macharia · Jomo Kenyatta University of Agriculture and Technology

Thank you Roy and Craig am going through the links provided

• Does anyone out there know what to make of Fst values being greater than Rst values for the same data set?

Usually (always?) it's the other way around, right? I have microsatellite data (8 alleles, 74 individuals) for a parasitic nematode collected on a microgeographic scale.  Rst is 0.077 and Fst is 0.149.  Any ideas?

Gislene Goncalves · Universidade Federal do Rio Grande do Sul

Doug,

I have been finding similar values of FST and RST, but so far not such difference (2x), which sounds really a lot (although I think it is not uncommon). Slatkin 1995 (A measure of population subdivision based on microsatellite allele frequencies. Genetics, 139: 457–462.) mentioned that when estimates of FST and RST are similar one each other, it suggests that organisms analysed differ similarly in distribution of allele frequency and allele size. So, I guess you might have a striking difference in one (or both) of these parameters.

Just a guess.

What's included in semiconductor module that AC/DC module doesn't have (from Comsol)?

Comsol 4.4 version have semiconductor module in it. Has anyone figure out what can be done through the semiconductor module but not through AC/DC module? It looks like semiconductor module is some calculation protocol that they combine through AC/DC and put it there.

Another way to ask this is: is it really necessary to purchase semiconductor module if we already have AC/DC module?

• Can you help me about the best on-line tuning methods of pid controllers?

classical methods

Marco Antonio Márquez Vera · Universidad Politécnica de Pachuca

Hi, you can use the gradient descendent method, it is easy for a PI or PD, when you uses three parameters it can be more difficult. When I need to use a PID, the reaction curve is pretty easy, to make it on-line you need to apply a step input, and by sampling the responce, you can approach a first os second model.

ts=4/sigma, tp=pi/wd, k=y(inf)/u(inf),

with these values you propose the gain to change the ts by using your model tunned on-line, then the integral gain suprime the error and the derivative term reduce the overshoot.

How to perform a gene ontology with topGO in R with a predefined gene list?

Hello,

I was wondering if the following approach is correct:

- I have a predefined list of the Ensembl gene IDs (n=28) and I want to perform Gene Ontology using topGO in R.

- I don't need to use expression values, but I do need to set a universe of genes. For that I chose all gene IDs available in Ensembl (n=64769)

If needed, the code can be provided.

Thanks!

Michael B Black · The Hamner Institutes for Health Sciences

Your gene universe should really be limited to the original set from which your significant genes were taken.  For example, if your 28 significant genes were derived from an analysis of whole human genome microarrays, then you would limit your gene universe to just the ensemble gene IDs for the human genome (which is something like 20,300 or thereabouts).

Gene ontology hypergeometric enrichment is derived from basic set theory.  It is just the probability of k successes in n draws without replacement from a finite population of size N containing exactly K successes.  If you arbitrarily over-define one of the sets for comparison (K or N), you bias your enrichment results.

When do we reject null hypothesis of not difference between groups in MRPP and Adonis?

I am utterly confused when is the hypothesis rejected in MRPP and Adonis. If I understand correctly, in MRPP we reject null hypothesis of no differences between groups when A = 1 and p <0.05 and in Adonis when R = 0 and p < 0.05. Is this right? The more I read about these two methods, the more confused I get. Can anyone explain this to me?

Javier Miguelena · The University of Arizona

Do you mean R2? I was curious about this because I am doing a similar kind of analysis. I looked it up and it seems that both A in MRPP and R2 in Adonis are measurements of how well the groups you propose explain the variation in the similarities or distances. The higher either of them are (closer to 1), the better we can predict the similarity of one item to others just by knowing what group it belongs too. Still, the main tool to test your hypothesis should be the p-value. If you are getting contradicting results, the problem might be that MRPP takes into account the spread within groups while Adonis does not.

How do you coat gold nanorods by PSS if they are stabilized by CTAB surfactant?

Gold nanorods are dispersed in a water solution with CTAB and sodium chloride.

How can I coat them with PSS polyelectrolytes.?

K. Morawetz · Universität Potsdam

Another possibility:You can use a polyelectrolyte solved in a non water solvent. Like PolyDADMAC in ethanol. Try to disolve PSS in other solvents

• DNA Preservation Reagent Suggestions?

I'm looking for a way to take an environmental water sample, then preserve the cells/DNA so that it can be shipped and filtered with sterivex about 2 days later?  Without using ice if possible....These are oilfield water samples so they will have some nasty things in them.

• I need to write a report on the use of a method in the detection of pollution incidents that does not involve taking a physical sample

the topic is environmental forensics