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.

Browse by research topic to find out what others in your field are discussing.

Browse Topics

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
  • Daniel Wehrung added an answer in Ultrasonication:
    How to improve ultrasonication efficiency?

    Hello everyone.

    I am performing a top-down synthesis of micro and nanoparticles and one of the final steps requires ultrasonication in order to achieve the desired particle size. During my experiments I have observed that the sonication power of the ultrasonic bath is not the same everywhere, which limits the reproducibility of the proces depending on where I place the flask with my sample (especially during microparticle synthesis).

    I was wondering if anyone had the same issue and managed to solve it. I am thinking of using a stainless steel mesh suport in order to try to create controlled regions in the bath with high vibrational efficiency thanks to the reflection of the ultrasonic waves.

    Are there any other ideas?

    Daniel Wehrung · Northeast Ohio Medical University

    Can you use a probe-type ultrasonicator instead of a bath?  Switching to probe sonication has given me more reproducible results, and decreased the duration required. 

  • John Y L Chiang added an answer in Bile Acid:
    Is someone aware of clinical studies on combating obesity with bile acids?

    Thank you.

    John Y L Chiang · Northeast Ohio Medical University

    Not directly for obesity. 

  • Chris K Neeley added an answer in Chemotaxis:
    Can anyone help me which cells to consider as migrated cells, cells on the membrane or cells in the lower chamber?

    I have some problem in migration assay. In the migration assay, which cells are better to consider as migrated cells, cells on the outer surface of membrane ( transwell insert ) or the cells transferred to lower chamber?

    Chris K Neeley · University of Michigan

    I've always just counted the cells on the bottom side of the membrane since it is difficult to account for cells that may have "fallen off" the membrane as they may simply be dead or dying (this applies to cells that are normally adhearent).  The cells should "stick" to that membrane and not travel further (most membranes are tissue culture treated to allow cells to adhere).  If you are getting a lot of cells in the lower well that you believe are viable then I'd suggest shortening your incubation time, generally I consider 24hrs as a maximum and depending on the chemoattractent as little as 4 hours can provide consistent results.

  • Is there a better alternative to FLASH tag?

    Dear ALL,

    We study a transmembrane protein complex (V-ATPase, 13 different subunits). The goal is to study V-ATPase trafficking in vivo (in cells). We need a short tag, not GFP (we already tried GFP, it does not work), one of them is obviously FLASH. However from the experience from our lab with the other transmembrane protein, FLASH gives a high background. Are there some other short tags with the lesser background and great results?

    Thank you for your help!

  • Andrii Tarieiev added an answer in Angiosperms:
    Taxonomy of angiosperms: what are the modern trends and techniques?

    Angiosperm represents the largest as well as the most successful group of plants within the Plant Kingdom. Taxonomy of Angiosperms started with two approaches viz. Empirical and interpretative approach. But with the advent of science and technology different methods and techniques are considered for better understanding and better approaches of taxonomy works. So, what are the modern techniques that can be applied in angiosperm taxonomy and why?

    Andrii Tarieiev · Georg-August-Universität Göttingen

    There are a lot of different techniques which are used for angiosperm taxonomy and also phylogeny. To these techniques you need more or less of specific equipmet and knownedge. In many cases some simpe methods is enough, but to make a precise taxonomy in most cases you must join different approaches to get consensus result

    1) morphologial and micromorphological features
    2) so called chemotaxonomy - biochemical features (i.e. secondary metabolites, proteins, some specific products or pathways and many others can be used in such way)
    3)taxonomy by genetic different molecular genetic markers (there are thousands of different markers from all genomes of plant cell used in taxonomy and phylogeny - for example rDNA, chloroplast genes and spacers, mitochondial genes)
    4) so called DNA-fingerprinting (include AFLP, RFLP, RAPD and many other techniques)
    5) full genome sequencing (this approuch never been used in taxonomy completely, but helpful in many cases)
    6) studuing differences in transcriptomes

    It is not full list of all techniques, it'sonly very brief review of it.

  • Saikrishna Srimadh added an answer in Cell Line:
    Which medium (DMEM, RPMI or MEM(E)) to use with the HIG-82 cell line can replace temporarily the prescribed Ham's F12K medium ?

    Dear All,

    Please help out ... We had ordered for HIG-82 Cell line (Synoviocytes of Rabbit) and it is delivered today. And the cells are confluent and ready to be split in to sub cultures. But, the Ham's F12K medium prescribed for the cells is still in transit. And we have DMEM, RPMI and MEM(E) media available in our lab.

    In worst case scenario, can any one of these media can be used for the HIG-82 cell lines before the Ham's F12 K arrives.

    Please help me in this regard...

    Saikrishna Srimadh · Sri Sathya Sai Institute of Higher Learning

    Dear All,

    Thanks a lot for your valuable suggestions...as suggested by you...

    Actually I tried DMEM and RPMI... The cells seem to be growing fine in DMEM medium but RPMI did not work out! 

    I got the HAM's F12K medium and now I shifted them to the new medium. They are growing well. 

  • Why did I get totally different melting temperature in ThermoFluor assay?

    I usually do thermoFluor assay with Tris buffer and I use suramin as a positive control for my enzyme to see shift in melting temperature. But when I used PBS instead of Tris buffer, the result is totally different. Usually I get melting temperature  43 degree, with suramin Tm is around 48 degree in tris buffer. When I did the experiment in PBS buffer, melting temperature is 51 degree which is higher than tris condition and there is no melting temperature shift for suramin which I use as positive control for screening my compounds. Does anyone have any suggestion to do my assay effectively for screening coumpounds?

    Magdalena M Makowska-Grzyska · University of Chicago

    Hi Afsana,

    There are many things that could be going on here. Do you have other proteins you could use as a control? Such as carbonic anhydrase, for which there is a lot of ThermoFluor literature data and Tm is ~58 degrees C. Just to see if your general experimental setup is correct. Why did you switch to PBS? Have you tested your enzyme and suramin interaction in PBS using any other methods? Also, you should probably avoid using Tris buffer in ThermoFluor experiments because the pH of Tris changes more with temperature than is the case with other buffers. I would suggest testing other buffers like HEPES or MES.

  • Chris Sutherland added an answer in Camera Trapping:
    Software for processing and collating camera trapping photos?

    Hi everyone,

    We are about to start processing photos from a camera trapping study. There are many many thousands of photos and I cant help but think there must be some neat programs out there to speed up or automate the process. So far, 'Camera Base' (CamBase) appears to be the wildlife ecologists' tool of choice. Anyone out there have any other recommendations?

    UPDATE: The identification of species will be done by eye (human). What I am looking for is  suggestions of programs that would facilitate the process of going through many photos and that would generate a database based on our identification.

    Thanks a lot!

    Chris

    Chris Sutherland · Cornell University

    Hi Matthew,

    Great, thanks for this. Looks like this is a good option for smallish numbers of photos. I wonder whether you find the need to do a lot of 'draggin 'n droppin' a little inconvenient? Looks like both CamBase and Snoopy provide a GUI that will do this stuff for you?

    I am compiling a list of programs, and this will be on it for sure!

    Thnaks

    Chris

  • Imran Aslan asked a question in Healthcare:
    Does anybody work in healthcare optimization?

    I want to get involved in that field from some countries.I have written my thesis in that  field. 

  • Anirban Bose added an answer in Logo:
    How to ensure watermark robustness under compressive sampling?

    I am trying to reconstruct a watermarked image through sparse signal recovery technique. I've taken a gray-scale LOGO image as an watermark and trying to reconstruct a watermarked image through BASIS PURSUIT principle but failing to retain the robustness of watermark under common image processing operation e.g. filtering, cropping etc. If anyone can shed light on  this then it will be highly appreciated. thanks in advance

    Anirban Bose · Indian Institute of Engineering Science and Technology, Shibpur, Howrah

    First of all a big apology to all of you for I didn't responded in time. I was busy in my phd work and as a result, this month, a paper is going to be presented at EUVIP-2014, France. I'm pretty excited. But, I sincerely would like to express my heartfelt gratitude for sharing your knowledge with me and thus enriching me, than you all. 

    @S.F. Russel an interesting concept but one question sir don't I need the pixel location/index at the time of detection and if I do then wouldn't it be an overhead to the information sent to the detector?

    @Lohweg: the links are really amazing but I was thinking could it done in a domain where the image is sparse / compressible.

  • Shaz Addy asked a question in Amyloid:
    What are the benefits of using ADAPP transgenic mouse model over humans in AD experiment?

    Hi,

    Currently, mouse models that completely replicate Alzheimer's disease does not exist. However there are transgenic models available.Would you please share any thoughts on the strengths of using APP (amyloid precursors protein) transgenic mouse model rather than having human subjects?

    I know it may be easier to get the mouse to follow the experiment(drug treatment and exercise), it would be faster to observe effects in mice since they only live a few years, and since human AD patients have both amyloid and tau and it is not currently understood which causes the other(if at all), it would be easier to elucidate the direct relationship between amyloid and drug/exercise treatments since the tau factor would not be involved...I feel like that is still not strong enough..can you share any other benefits(or even of using transgenic mice models of AD over human subjects)?

    Thank you in advance.

  • Shevali Kansal added an answer in PCR:
    Can anyone suggest alternatives for ethidium bromide in terms of a non-toxic DNA staining dye?
    Many alternatives are available commercially, including non-tox, fast-blast, EZ-vision, Redsafe-DNA, etc. but I am not sure which is best. Does anyone have any experience with this? Any suggestions?
    Shevali Kansal · The Forsyth Institute

    SYBR safe is a good option...

  • Marta Gandolla added an answer in Exoskeletons:
    Can anyone recommend me some research work published about clinical evaluation of upper limb rehabilitation in patients with the use of exoskeletons?

    There are now many research papers on prototype exoskeletons for upper limb rehabilitation in patients with stroke survivors, most of them concern issues related to the design of the different components: actuators, interface and control systems, however only few of them include a deep clinical evaluation. Can anyone recommend me some research work published on the most comprehensive clinical evaluation of upper limb rehabilitation in patients surviving a stroke with the use of exoskeletons?

    Marta Gandolla · Politecnico di Milano

    If of interest, I can also suggest the one attached from my group. If you have any question, please do not hesitate to contact me.

    All the best,

    Marta

  • Jean-Luc Nespoulous added an answer in Syntax:
    Is it possible to test syntactic understanding without requiring semantic knowledge?

    Naive question from a non-linguist. The basic distinction between syntax and semantics is clear; but I'm not sure how one might assess a person's understanding of syntax without requiring some degree of semantic knowledge. Even in jabberwocky sentences (which have English grammar and syntax but with nonsense words), the so-called "nonsense"words do suggest meaning. I'm interested in examples of "syntax without semantics" in both music and language. 

    Jean-Luc Nespoulous · University of Toulouse 2 - Jean Jaurès

    Using "reversible sentences" makes it possible to assess syntactic parsing/comprehension in sentence/picture matchings tasks bypassing both semantic and pragmatic constraints. "The horse follows the cow on the lane" vs. ""The cow follows the horse on the lane". See also the Token Test with geometrical figures. Both these tasks are very often used to assess syntactic processing in aphasic patients (cf. Nespoulous et al. 1986)

  • Muhammad Sarwar asked a question in Crop Physiology:
    At 32-36C if regulators/ nutrients use as foliar: antioxidants, physio. parameter, yield increase in some what quantity as in stress than the control?

    Botany, plant and crop physiology, heat stress, growth regulators, soil science,cotton

  • Barry J Shelp added an answer in Phloem:
    Is anyone familiar with phloem sap extraction from brassica?

    Hi, I want to extract the phloem sap from brassica by existing protocol "phloem exudate extraction from arabidopsis" but I am unable to get the RNA from the sap. What kind of precaution should I take during an experiment. I have collected the leaf sample in 20mM K2EDTA and then kept it for overnight in 2 ml tube containing autoclave deioninzed water+ RNase inhibitor, place the setup in wet tissue towel containing desiccator.

    Barry J Shelp · University of Guelph

    See J Exp Bot 38:1603 (1987) for sampling phloem from broccoli without the use of EDTA, which may be problematic for subsequent analysis. I have found that it can be similarly sampled from flowering stalks of Brassica napus. Never tried it with Arabidopsis.

  • Renzo Bianchi added an answer in Psychology:
    Does anyone know psychologcial / cognitive stress induction task?

    Does anyone know any psychological / cognitive stress induction task? Or maybe some review paper. I mean any other than TSST.

  • Rajaram Chenna asked a question in Ground Motion:
    Will we get the same linear and non-linear responses for a structure subjected to both normal and synthetic ground motion?

    We have a ground motion records for a site. Also, generated ground motions for the same site using analytical methods. The characteristics of both ground motions are similar. Will we get the same linear and non-linear responses for a structure subjected to both normal and synthetic ground motion?

  • Samantha Shaltz added an answer in Ligases:
    What tips do you have for blunt end ligation with a large vector and a small insert?

    I cannot get my blunt end ligation to work on a large vector (9kb) with small insert (500bp) The insert was isolated by PCR using pfu pol., then gel extracted and purified.

    For the vector, I performed two separate digests with the same enzyme to ensure most is cut. Then I used klenow to blunt ends of the vector, purified to remove EDTA, and phosphatased vector with AnP.

    With the ligation, i have tried many different amounts of vector to insert ratios to add, between 3:1 to 8:1, and never had luck. I have used NEBs quick ligase and T4 ligase at different times, always following their protocols. The transformation seems to work with the pUC19 control so I think the ligation or the klenow step is the issue.

    I do know the AnP is working because my vector only with ligase gives no colonies after transforming. I have also know the digests work due to running my products on a gel. My only ideas now are the ligation or klenow step not working right.

    Samantha Shaltz · Duke University

    Unfortunately I need the large vector. The large vector is actually another clone I made with a specific large fragment. The insert I am trying to put into it is the promoter I need for that particular fragment. 

  • Can anyone tell me the names of labs where probiotics are being grown and tested?

    I would like to interview a scientist working in the field right now.

    Seyed Hossein Hoseinifar · Gorgan University of Agricultural Sciences and Natural Resources

    Dear  kathleen

    I have been working on Pro and prebiotic since 2007

    You can send me message or email

    hossein.hoseinifar[at]gmail.com

  • Anne Solga added an answer in Pull-Down:
    Can anyone recommend a good antibody to do an IP for CCL5 (RANTES) in mouse tissue?

    I am looking for an antibody to do a Ccl5 pull-down in mouse tissue. All the ones I have found so far only work in human tissue. Thanks in advance! Anne

    Anne Solga · Washington University in St. Louis

    unfortunately none of them are recommended for IP. Thanks though!

  • Peter Mould added an answer in Medical Imaging:
    How does the choice of signal transfer property affect the final presentation of a medical radiograph?

    i.e. CR/DR log/linear

    Peter Mould · Betsi Cadwaladr University Health Board

    By signal transfer property (STP) I mean the relationship between pixel value and air kerma. The relationship between pixel value and light level is standardised by the DICOM GSDF.  So is the system STP masked by anatomical image processing, or does it affect the presentation of the final image?

  • Miguel Belbut Gaspar asked a question in Callbacks:
    Why is my event-loop in matlab non-gui executable not working?

    I am developing an application that should run in the command-line (console application), without gui. I want to reduce the memory footprint and load time. My application will be controlled trough a network connection. In Matlab I can have the callbacks persist after the script/function exits. In the compiled version,  I have included a pause(), to prevent the application from terminating. But when I run the compiled version it doesn't seem to respond to the callbacks. As there is no wait() for tcpip objects, I don't know how to keep the app. from exiting. Am I doing anything wrong? Is what I want possible, or do I need a Windows executable to have the event loop for the callbacks?

  • Tuning fork hearing tests sensitivity versus Pure tone audiometery (PTA) sensitivity- which is confirmative to the other?

    The tuning fork test is a well established worldwide tool for primary hearing assessment.  It can differentiate between CHL & SNHL. Can a tuning fork test be used to confirm PTA in cases of non-organic hearing loss (NOHL)?

    Max Stanley Chartrand · Northcentral University

    Glad to see a queston on tuning fork tests. We see this as a lost art and yet as a qualitative tool to understand the progression of pathologies as well as to verify patient verbal and case history complaints, tuning fork testing serves a vital need. In my work, which for the past half dozen years has been almost all in behavioral medicine (still some consulting for otolayngology and audiologist clinics), I find using the tuning fork tests (Bing, Schwabach, Rene) invaluable at finding impending heart issues. The heart sinus node tone of the vagus nerve branch in the 3.5-4.5 Hz region can be detected by matching patient complaint of a "high pitch ring" to the 4KHz fork, and from there help in deciding whether to refer to a cardiologist first or to start first with the audiologist to determine if hearing loss is at root of the complaint. We find, and this is anecdotal and relies upon other information, that a tinnitus complaint at about 4KHz and thresholds are perfectly normal at 4KHz in audiometric testing, that pericardial sac inflammation is suspected and points to the need for a thorough cadiac investigation. This may seem a bit off topic, but is pertinent to both the need for tuning fork testing as a quick screening procedure and the need to refer for a complete audiological battery. 

  • Marc Tessera 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.

    Arnold,

    I notice once again that you don't answer my question to you about locating your retinoid neural network: any problem with it?

    I disagree with your assertion that a locked-in syndrome patient is totally disembodied as the patient still have some proprioception. Anyway, the feelings of the patient are likely affected by the syndrome.

    In Azheimer's disease I agree that the default-mode network activity becomes abnormal at a later stage of the disease. Of course, at that stage, the feelings of the patient are clearly affected by the disease.

    What do you want to prove?

  • Abena Bemah asked a question in QIAGEN:
    How do i get obtain more DNA from blood and mouthrinse samples?

    My lab is currently experiencing a little difficulty with the concentration of DNA we obtain from our blood and mouthrinse samples...we used to use the Lymphoprep protocol until some few years  back when we switched to the Qiagen Kit.... but we seem not to get the more concentration of DNA now....what can we do to improve on the concentration of DNA we get from our samples using the Qiagen Kit.

  • Farzaneh Keyvanfard added an answer in DCM:
    Are there any Normal Brain MRI dataset in .dcm file?

    my research is about brain tumor, i was searched information about normal brain axial plane MRI dataset. i was found that extension file .nrrd , .img, but i dont find the dataset in .dcm extension. please help me.

    Farzaneh Keyvanfard · Amirkabir University of Technology

    Dear Halima

    I think you can find your desirable data in the following link:

    http://www.humanconnectomeproject.org/

    Regards

  • Rene Galindo added an answer in PID Control:
    How do I tune a multi-loop PID controller (in MATLAB) ?

    I'm interested to design a PID controller for two links robotic arm (one for each joint angle), I got very bad response by few trials. So, is there feasible method could be used to figure out this issue.

    Any suggestions?

    Rene Galindo · Autonomous University of Nuevo León

    As Alexandre Janot write, if the robot is considered as a perturbation for the motors, I suggest to get the inertia of the robot M(q) from the kinetic energy T expressed in matrix quadratic form T = 0.5 transpose(dq/dt)*M(q)*dq/dt, and then the diagonal elements of T are used to tune the PID (see the book of Spong and Vidyasagar, Robot Dynamics and Control). Since the inertia is a function of the configuration of the robot you can actualize its value on-line or take the suggestion of Alexandre (maximum value). Another control technique is feedforward control in which the compensation can be gotten off-line or computed torque in which the Dynamic Model of the controller is computed on-line.