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

  • What information is contained in the phase spectrum of a signal?
    I often read articles in which the authors compute both the phase and the amplitude spectra. I know what the amplitude spectrum is but I just can't make sense of the phase spectrum.
    Moshe Nazarathy · Technion - Israel Institute of Technology
    I give you two different signals with the same amplitude spectrum but with different phase spectra. Are the signals gonna like identical in the time domain. Hell, no. This means that the phase spectrum is an essential piece of info (along with the magnitude). Alternatively, one can represent the signal by its I and Q (in phase and quadrature components). Complex representations of signals always have two components, magnitude and phase or real and imaginary parts. A related reason why phase is so important is that nature (quantum mechanics, electronmagnetics) is based on INTERFERENCE. Waves of given magnitudes interact via their phases in order to yield the amplitudes of their resultants. For example adding two identical sinusoids of the same phase doubles it, whereas adding two sinusoids of the same amplitudes but phases with 180 deg difference wipes the resultant out.
  • Pedro Simão added an answer in Pursuing PHD
    Is it necessary to have published articles to get PhD admission?
    Any opinions are highly appreciated.
    Pedro Simão · University of Aveiro
    In my University it is not mandatory. However, the more articles you publish the more respected your studies will be. Also, on a personal view, it is fantastic to see other people appreciate your contributions. I don't think publishing articles should be mandatory to get an admission to a PhD but while you are attending PhD classes and completing your thesis, publishing should be an important step.
  • Michael Patriksson added an answer in Energy
    What do you think are the most important personal characteristics of a successful researcher?
    Is there in your opinion some personal characteristics that are recurrent in successful researchers? What is opinion about the following personality traits? 1. Intellectual curiosity, 2. determination, 3. self-motivation, 4. competitiveness, 5. team-work capabilities, 6. humbleness, etc. Are there other relevant issues that I have not mentioned? Do you feel there is a logical importance ranking among the above mentioned characteristics? Do you think the ranking depends on the specific research field or on other issues?
    Michael Patriksson · Chalmers University of Technology
    In the original list, capability is only mentioned in relation to team-work. But think about the classic notion of any qualified skill needing 10,000 hours of hard work of preparation, as has been mentioned by many, irrespective of your field being in science, finance, in the arts - anything sophisticated enough. Ability/capability does count for a lot, and cannot be replaced by determination. I would say that capability is necessary, but not sufficient. To ability one must add curiosity and perseverance. Depending on the field, success may depend on many other things, such as luck :-), or - as was mentioned - team-work capabilities, including leadership capabilities. In pure mathematics people still work in teams, and unless you are humble, let's say, you may have a hard time letting many, many hours of proof-reading go by, and you may lose the chance of proving that elusive theorem correctly. :-)
  • Why do we modulate a signal during transmission and demodulation during receiving? Why don't we send a signal directly without modulation?
    What is the purpose of doing this?
  • Query on signal's direction of arrival in VANETs
    Hello, In VANETs, we read alot about classifying the packets arriving at vehicles as being either arrived from "vehicles at the front" or from "vehicles at the back". However, I am interested to know about the theory behind the detection of signal's direction of arrival in VANETs. What equipments are used in that? Does positioning devices, such as GPS or GNSS modules play a major role, and what is the theory behind it? Regards,
  • Angel Irabien asked a question in Very interesting paper. Do you know applications?
    Capture Applications
    It is very important to know about carbon capture application of membranes
    State-of-the-art membrane based CO2 separation using mixed matrix membranes (MMMs): An overview on current status and future directions Mashallah Rezakazemi, Abtin Ebadi Amooghin, Mohammad Mehdi Montazer-Rahmati, Ahmad Fauzi Ismail, Takeshi Matsuura
  • Edward H Kilson added an answer in Exoplanets
    How significant is the discovery of Kepler-186f, an earth-sized habitable zone planet?
    Kepler-186f is the first earth-sized planet located in the habitable zone of another star that has been discovered. With this discovery, the search for life on other planets has entered into a new zone of discovery.
    Edward Kilson · Center For the Early Detection and Humane Treatment of Satyriasis
    I would think what IS interesting about this new planet is that it is a similar size to earth for this reason. It's likely to have a gravity that could foster intelligent life.
  • Imtiyaz Rather added an answer in Gravity
    In general relativity, how is gravitational force replaced by space-time geometry?
    How, in Einstein's theory of gravity, can one replace the concept of force with that of the deformations of space time? Why is the orbit of mercury described better in terms of Einstein's theory in comparison with Newton's theory? A reference link: http://www.einstein-online.info/elementary/generalRT/GeomGravity
    Imtiyaz Rather · University of Phoenix
    A general relativity by "sir" Einestein is like E=mc2 and the mass of the object at the space orbit turns (0) zero means a micro gravity on the other side of the fact the object like satellite lives in a hanging means free floating in air only beacuse the the object occupies a balanced space against equal forces same as in atom where, the protons and neutrons live in the centre of nucleus and the electrons move around in a electron cloud in an equillibrium the fact is that so far only atomic clocks are calculating but nuclear will be future because the momentum of exoplanetry or endoplanetry is always against each other like we find on earth.The recent discovery is anything that is away from you is in momentum that is relativity.
  • Kenneth Towe added an answer in CO2
    398 ppm - are we beyond the tipping point?
    The latest (2014) measurements from NOAA show that the atmospheric CO2 concentration of Earth is ~398 ppm; nearly 100 ppm beyond the highest historical CO2 concentration measured in the past >400,000 years. Are we beyond the tipping point of minimizing the effects of climate change, in which we should be focusing more on adaptation (e.g., building up land) and less on prevention (e.g. slowing emissions)? Conversely, should we continue focus more on prevention/mitigation, or do we need to consider both equally?
  • Does anyone knows the best method to measure receptor recycling or trafficking?
    I am trying to evaluate if heavy metals affects receptor recycling, I use NRK52e cells, I have Alb-FITC but i don't have good results.
  • Satyaprasad Venkata added an answer in Antibiotics
    Do you treat acne with isotretinoin as first line drug?
    Or do you try other treatments first like systemic antibiotics or topicals ?
    Satyaprasad Venkata · Manipal Hospital, KAYA
    The most common drug isotretinoin has the most flexible dosing to control acne. Often the problem would arise when a young lady has acne before her marriage,. At what dose is isotretenoin safe not to cause any fetal abnormalities.
  • Sanda Kaufman added an answer in Mediation
    What are some examples of Conflict Transformation?
    I love the concept of conflict transformation. To me it's saying that there is a win-win solution to conflict, but I really have no concrete examples of a conflict that was transformed. And can this concept apply to personal conflicts, such as phobias, as well as conflicts between groups and people? Any there any examples were conflict transformation is brought about by some external event or force, something that was not foreseen?
    Sanda Kaufman · Cleveland State University
    Gita is right - almost any experience can be transformative (regardless of the conflict's outcome). However, "transformative" is a specific term applied to a specific approach. Here is a citation: Joseph P. Folger and Robert A. Baruch Bush, "Transformative Mediation and Third-Party Intervention: Ten Hallmarks of a Transformative Approach to Practice," Mediation Quarterly 13:4 (Summer 1996) pp. 263-78. (Folger and Bush coined the term, but there has been a lot of writing on the subject since they proposed this term.) One example of use of this technique is in the US Postal Service, which has adopted it for resolving work disputes.
  • Evans Ehouman asked a question in Analytical Methods
    Is there a way to determine the cytotoxicty of a substance after assessing its viability effect?
    I want to carry out the MTT test to show the viability effect of plant extract on cells lines. Is there a way to reveal the cytotoxic effects of these same extracts.
  • Why farmers dont adopt the technologies generated by scientists?
    What are the factors which govern the adoption or non-adoption of any technology generated by scientists. In developing countries like India, small and marginal farmers do not adopt even a low cost technologies in some regions. They need zero cost technology or managemental type of interventions which is not always possible. If we give financial support, they will agree otherwise chances of adoption becomes meager. How this cost factor be minimized to improve the adoption rate. Where are we lacking?
    Gonzalo Galileo Rivas Platero · Instituto Interamericano de Cooperación para la Agricultura
    Completely agree with your approach Graeme, market linkage is key in this process for producers. Field schools and participatory approaches should also consider the context of agrifood chains; where networking is vital to this process. In recent years, in Central America, we have been developing actions with value chains for maize and beans in the scheme of innovation networks with strong leverage technology and business management knowledge.
  • Which is the best choice to determinate qPCR amplification efficiency? cDNA, gDNA or plasmid serial dilutions?
    Dear colleagues I'm working with qPCR relative quantification and I need to determine the efficiency of qPCR amplification. I know we can use dilution series from gDNA, cDNA or template inside a plasmid, but what are the advantages and drawbacks of each one? what is the best choice? I would really appreciate if you can guide me Thanks in advance My best regards
    Amir Mizbani · ETH Zurich
    I was looking for an answer to a different question, and saw this discussion. Just wanted to comment on a point which is apparently getting quite frequent and consensus: "use the same kind of input for your standards as you have in your unknown samples". Sentences like "contexts should be the same" etc. are used to support this idea. This often leads to the conclusion "so if my unknown sample is cDNA, I use dilution of cDNAs for making standard samples", which is not a good idea indeed. I have experienced it, and I recently found it published years ago (attached to this message), that using dilutions of cDNA gives you higher-than-real efficiencies, since some components of RT reaction (most likely the RT enzyme) inhibit PCR reaction. This makes the amplification of more diluted cDNAs easier (more efficient), so they come up earlier than expected, and this leads to calculating higher efficiencies, which are sometimes above 100%. So if you want to have cDNA as std sample, to prevent such miscalculation you should spike a negative cDNA (name it A; e.g. from a tissue which does not express your gene of interest) with different amounts of a positive cDNA (name it B); for instance, use samples composed of 100% A, 25%A+75%B, 50%A+50%B, 75%A+25%B, and 100%B as standards; obviously if you want your std curve to fully cover your unknown Cts, B should have expression higher than any of your unknown samples. This is how you "keep context/structure the same", by avoiding "diluting the structure!". The next alternative way can be using dilutions of PCR product of the same primers (better if purified). Since you have to dilute them several orders of magnitude, there is virtually nothing else than the template DNA there in your std reaction (in my hands a 1:5000 dilution of a PCR product gives a Ct of ~10 in qPCR). You can even use serial dilutions of this to spike a negative cDNA sample and use to make stds. The only thing to worry about in this case is the difference in efficiency of primers annealing to that short DNA strand compared with real cDNA strand. The next way could be using plasmids as mentioned above, and the last (and furthest from ideal) will be diluting a cDNA!
  • Monire Ahmadi asked a question in Economic Analysis
    How can we measure the inflation expectation for every years ?
    Is that average the weighted inflation target in past years?
  • Imtiyaz Rather added an answer in Collaboration
    Would you like to collaborate on a research project?
    We do have experts in all fields, don't we? Why shouldn’t we start a really nice and great project together? What we need are some good suggestions of general interest for mankind, a review jury of up to 8 members (including finances and management researchers) for the max. 3 pages suggestion. After the project gets the OK, a time planning has to be set up, with milestones and short reports on the progress of the work. The financing of such a project should come without much bureaucracy from independent research companies, presented in RG. The max. time should be 3 years. This could be a proof for the ”RG-GATE” aim itself and chances for a transdisciplinary community. ATTENTION: This will be not an EASY project.
    Imtiyaz Rather · University of Phoenix
    A better callobration in growing science is a real time for, i would certainly like to join the project at the best of efforts "thanks'
  • Thought comes before language or thought and language are interdependent processes?
    Regarding the role of language for development and the relationship between language and thought: According to Piaget, thought comes before language, which is only one of its forms of expression. The formation of thought basically depends on the coordination of sensory motor schemes and not of language. This can occur only after the child has reached a certain level of mental abilities, subordinating herself, to the thought processes. The language allows the child to evoke an object or event absent at the communication of concepts. Piaget, however, established a clear separation between the information that can be passed through language and processes that do not seem to suffer any influence of it. This is the case of cognitive operations that can not be worked by means of specific training done with the aid of language. For example, you can not teach, just using words, to classify, to serialize, to think with reversibility. As for Vygotsky, thought and language are interdependent processes, from the beginning of life. The acquisition of language by the child modifies its higher mental functions: it gives a definite shape to thought, enables the emergence of imagination, the memory usage and the action planning. In this sense, language, unlike what Piaget postulates, systematizes the direct experience of children and therefore acquires a central role in cognitive development, reorganizing processes that are ongoing.
    Sanda Kaufman · Cleveland State University
    It seems thought and language are related, at least according to Guy Deutscher, whose book on this topic I recommend warmly - it is a great read and makes the case for this link in a very compelling fashion. He explains how difficult it is to answer this question definitively, but also uses already available information For example, he shows that the color names available in one's language affect what we think we see, which varies across cultures and languages. He makes a similar case using the example of spatial orientation (whether by cardinal points or a system of coordinates) which also affects how we see reality.
  • how can i get a homogenous film from TiO2 to be applied in dye sensitized solar cells?
    I tried to make TiO2 paste using dilute nitric acid but it gave a cracked film so i'm asking how can i get a homogenous film on ITO glass substrate.
    Anil Kumar · National Institute of Technology, Kurukshetra
    Dear Eman Mohmed, I'm pursuing PhD . I'm also working on the DSSC applications. if you are using spin coater, it is better to use the homogenous solution of TiCl2 which is an precursor solution of the solgel technique and regarding the adherence you can heat the substrate on the hotplate after the film was suppose to be deposited for sometime it will enhance the crystallanity and the adhesive property of the film developed. it is important to note that the rpm and time plays a crucial role in developing the film.
  • Is sugar over consumption the underlying cause of the obesity epidemic?
    The current obesity paradigm is basically behavioural; overeating and under exercising as the cause of obesity. Both true but neither has explanatory power unless people deliberately set out to become obese. A single underlying cause is the over consumption of sugars. It fits the descriptive epidemiology: pandemic, both genders, all ages, increasing since the 80's, high prevalence. It fits the biochemistry as causing insulin resistance via glucose consumption stimulates appetite and reduces exercise. It fits the epidemic of Non Alcoholic Fatty liver Disease through fructose. This model supports both individual and public health responses: low sugars diets and low sugars food availability. It also supports recent observational studies and meta-analyses that fats are part of the solution, not part of the problem. Until the paradigm shifts back to the pre-50's diets, we will continue to do the ineffective, calorie restricted diets and increasing exercise, instead of decreasing sugars intake both as individual interventions and public health policy.
    Claudia Strauss · Queen Mary, University of London
    Luke, you said: "However, obesity is almost impossible to reverse not because “body goes into energy sparing mode” but because people involved in the research, prevention and treatment of obesity don’t know how to reverse obesity." Fair enough. However we do have evidence that obese and overweight people manage to get their weight down through calorie sparring. But it does not last. If you follow Atkins, Paleo or calorie counting, the long term outlook is bleak in each case. I don’t have the answer why this is the case, but I am highly suspicious of people claiming “ I found the holy grail, just cut out [insert your current favourite theory, in this case fructose]”. All we know is that if you eat more calories than you burn, you gain weight, if you eat less it is not that simple. The theory still works. And if we would have (unethical) access to a group of people where we control intake 24/7 for years I am confident these people would lose weight and stay the same. But we are not dealing with lab conditions, we are dealing with humans in a highly obesogenic environment. And if we wont to make a difference, we need to take everything into consideration. And the last thing we ought to do is blaming the patient for not following out ideal lab conditions. Which might be right..or wrong.
  • What is the purpose of dreams?
    Sigmund Freud, the founding father of psychoanalysis, first became aware of the implications of dreams in psychoanalytic therapy when he comprehended that in the process of free association, his patients often described their dreams pertaining to the night before. He then learnt that these dreams had a certain meaning, though this meaning was concealed. “The Interpretation of Dreams” was published by Freud in 1900, and in which he incorporated much of the data gathered from both his clinical experience in this domain as well as the insights he acquired by free association for his own dreams. It was on the basis of this data that he came to the conclusion that a dream is a conscious expression of an unconscious wish or fantasy, which is not accessible to that individual in the awakened state. Dreams dwell in a central spot in today’s psychoanalytic practice and theory, and are the subject of ongoing research. However, to date clinical psychiatric treatment has not yet clearly elucidated the value of dream interpretation. So, what is the purpose of dreams?
    Ziad Abu-Faraj · American University of Science and Technology Lebanon
    Happy Easter to all friends!
  • What are the factors that make the analysis of your data set difficult?
    For instance, unstructured data and lack of ground truth pose a great challenge in my case!
    Dony Saputra · Surya University
    Analysis of dataset is difficult when there is too many variance lays over it, noise or deviation is to big and wide area of data spread. Most of its came from wide are of data spread, from statistical view range on distribute frequenti are to close but the data set spread rarely on that range
  • When we function porous nano particles, the density is changed. How can we calculate the changes?
    When we embed these functioned nano particles into polymeric membranes, in order to compare with un-functioned particles it should maintain the weight of un-functioned particles in both membrane.
    Imtiyaz Rather · University of Phoenix
    To determine the changes of a porous material like gypsum (calcium dihydrate) or a gel like agar while filtering through different liquid mediums can give a variable degree of filtrate that will define and show crystral change through different medium.
  • Ziad O. Abu-Faraj added an answer in Wikipedia
    Is Wikipedia an acceptable source of information for Research & Development?
    Wikipedia, formally launched on January 15, 2001, is a collaboratively edited, multilingual, free Internet encyclopedia that contains over 30 million articles written in 287 languages written by volunteers around the world. Given its wealth of information, has Wikipedia become an acceptable source of information to be used in Research & Development?
    Ziad Abu-Faraj · American University of Science and Technology Lebanon
    Happy Easter to all friends!
  • Pat Bailey added an answer in Global Studies
    Would an increase to the current global population be of any benefit?
    Given that we now have approximately seven billion people on our planet, and all of the problems that follow, is there any benefit to continue growing our numbers?
    Pat Bailey · Santa Fe College
    Hi, Nathalie. Thanks for your response. This is a question I took an interest in, about two years ago, after having seen it raised in a book about research ethics. I found it puzzling because I'd never stopped to consider it. After having it brought to my attention, I spent a great deal of time trying to think of beneficial reasons to continue to increase our numbers. I couldn't think of a single one that I found sufficient, which made me then ask whether or not we have a moral obligation to decrease our numbers or, at the very least, improve the efficiencies of our existing systems (political, social, economic) so that they more effectively meet the demands of the current global population. There is little doubt, I think, that our current methodology (especially if the US is the example) is an unsustainable enterprise. Here, I'm reminded of one of my favorite quotes related to these ideas: "It is not necessary to change. Survival is not mandatory." - W. Edwards Deming
  • Jack M Gallup added an answer in Fraud Prevention
    Why are there increasing fraudulence issues in science?
    As many might notice from news, fraud and misconduct in science are becoming serious issues in recent years. Does scientific misconduct relate to disciplines? What discipline do you think is more likely to have unethical issues, and why? What is the solution?
    Jack Gallup · Iowa State University
    Negative results are so very important to report though as well. Negative results are results always worthy of mention. There are now journals dedicated to the reporting of negative results. These are crucial parts of the entire picture. I think Stephen Joy has a really good series of points above. This is a troubling issue. It is also, perhaps, just one particular shade of the expected spectrum of human behaviors only this time being played out and exposed in the scientific arena. In sports people have secretly taken testosterone or performance enhancers to look like a super-hero. In science, some people choose to fudge the results. These people have to live with themselves afterwards, and hopefully those who practice dishonesty in science don't eventually cost some lives as a result. That would be the worst outcome. The truth is one of those commodities we, as humans, should always try to nurture. Without it, all is lost - including our self-worth as living beings. Brutal honesty in science is an absolute must. The growing disconnect between administrators, PI's and lab workers may foster the unthinkable on occasion it appears, sadly.
  • What are (in your opinion or knowledge) the variables involved in the imagination of future?
    For example, could temperamental traits influence positive or negative feelings about future?
    Catherine Widmann · University of Bonn - Medical Center
    Dear Amelia, I was referring to the type of imagined future self among people trying to improve something (quitting smoking, losing weight, learning to deal with anger, etc.). That is what I am most familiar with, although it is not my field. I would encourage you to consider what this literature has to say, since they have general findings on variables important to imagining a future self - even potentially a negative one. You might also like to look into predictors of job- and academic performance, which will overlap to an extent with the idea of imagining a future self. I wish you all the best! I am curious what your exact research question is.
  • Can anyone help with BOD value?
    I took the sample of sewage waste water from an oxidation pond and observe the BOD value is less but when I took the sample from the outlet of same pond the BOD value is high. Can anybody justify that?
  • Oliver Manuel added an answer in Universe
    Is there a reasonable alternative to the theory of the expanding universe?
    We know that our star, the Sun loses about 10^-14 of its mass per year as a result of electromagnetic radiation and particle emission. That reduction in mass should show up as a decreasing gravitational red shift. Same thing should happen to entire galaxies. But isn't it true that the galaxies we observe that are farther from Earth are also the younger we see (because light has taken millions of years more to come to us) and, as a consequence the more massive when we consider entire galaxies? (Because we cannot possibly see them as they are, but as they were millions of years ago.) Shouldn't we expect, correspondingly that the gravitational red shift of an observed galaxy will increase with its distance to Earth?
    Oliver Manuel · University of Missouri
    Thank you for your kind and insightful response, Barry. Question: Does the Second Law of Thermodynamics prevent perpetual motion in an infinite, cyclic universe? Answer: I think not. The Second Law of Thermodynamics is valid and prevents perpetual motion in an expanding universe, where entropy only increases. The entire fabric of physical science was corrupted after the end of the Second World War to obscure the source of energy that destroyed Hiroshima and Nagasaki. See ongoing discussion: http://stevengoddard.wordpress.com/2014/04/19/a-different-view-of-extreme-weather-from-1975/