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  • Peter Gray asked a question in Pterygium:
    Do pterygia develop after Lasik ?

    I have a patient who developed a pterygium after lasik and have colleagues also observed this ? 

  • Stam Nicolis added an answer in Black Holes:
    When two black holes merge, what actually merge ? How to merge their singularities and their event horizons ( or apparent horizon)?

    We did not identify the black hole in full detail yet. Does  it has an event horizon or appearent horizon. We are trying to modify our theory to resolve the problem of singularity. Is the black hole without singularity still be a black hole? What is the main character of the black hole, the singularity or the event horizon.

    Stam Nicolis

    It's useful to actually read Hawking and Penrose's paper:  http://rspa.royalsocietypublishing.org/content/314/1519/529

    and then explain how the assumptions of the theorem are evaded.

    The Schwarzschild (and Kerr) solution is an *exact* solution of Einstein's equations, not an approximate one. Once more it's wrong to confuse mathematics with physics. Whether astrophysical black holes exist or not can be debated, though to what purpose seems strange, now that measurements seem to confirm that their behavior can be accounted for-whether the mathematical expressions for the Schwarzschild or Kerr metric do solve Einstein's equations, with appropriate boundary conditions can be trivially checked to be true, so there's no point claiming otherwise. What the singularity theorem of Hawking and Penrose implies is that generic initial conditions lead to gravitational collapse-so if the claim is that such a collapse can be avoided, what should be spelled out is in what way the modifications evade the assumptions. 

  • Mehmet Sinan Iyisoy added an answer in Splines:
    Should My statistical model be flexible or not ?

    Assume that I have a large number of predictors and a limited number of observations; How should I build the statistical model? should it be flexible (Spline) or inflexible (Linear Regression)?

    Mehmet Sinan Iyisoy

    There are other ways of regression when sample size is small than the number of predictors. Please have a look at Lasso.

    About flexibility, I think Lasso is more flexible than the methods you mention. If you need even more flexibility, there is Elastic Net (this is not a joke).

  • Vincenzo Forgetta added an answer in DNA Sequence Alignment:
    How do one teach someone to understand the global and local alignments to a person who is new to bioinformatics?

    How can one understand the sequence alignment in a more practical way based on the local and global alignments.

    Vincenzo Forgetta

    This answer seems pretty clear:


  • Benno Schmidt asked a question in Geovisualization:
    Why do people like maps and geovisualizations?

    Maps and other kind of geovisualizations such as globes, interactive 3-d worlds etc. seem to be very popular and fascinate a lot of people. But what is the reason for this (just aesthetics, potential immersion/fantasy firing, exploratory spirit, ...)?

    Well, of course there are a lot of threads in the Web that deal with this question. But for me, the answers I found there are not really satisfying (often fuzzy, not pointing-out the core issues). Who knows research works, scientific papers, or useful Web-links addressing this topic?

    If we knew what makes geovisualization such interesting, maybe we could export these ideas and concepts to other domains, e.g. to set-up interesting user interfaces for (non-geospatial) applications, or to design innovative experiental spaces, etc.

    I'm curious about your thoughts and ideas!

  • Otávio Bravim asked a question in FDA:
    Does anybody knows where I can find a list of all monoclonal antibodies approved by FDA updated until 2015?

    I'm writing a chapter and I need a recent list that contains all monoclonal antibodies and its applications and it is being very hard to find. If anybody could help me I'd appreciate it. Thanks!!

  • Ivan A. Hashim added an answer in MATLAB:
    How to pull out numbers from a vector in matlab?

    I am having trouble figuring out how to extract certain points out of the vector I create.  The point of this problem is to create a function that finds the first nth prime numbers without using native matlab functions.  I create a large matrix that I narrow down to create one that has a large number of prime numbers.  Then out of that function I pull out the first n prime numbers.  I keep getting an error that says "Index exceeds matrix dimensions.".  Any help would be great. The function is below:

    function [ prime ] = HW01_problem_07( n )
    %UNTITLED Summary of this function goes here
    %   Detailed explanation goes here
    array = 2:N;
    for i = 1:length(array)
        if array(i) ~= 0 
            for j = i+2: length(array) 
                if mod(array(j), array(i)) == 0 
                array(j) = 0; 
            if array(i) ~= 0 
              prime(length(prime) + 1) = array(i);

    Ivan A. Hashim

    Hi Richard,

    the following is the correct MATLAB script

    function [ prime ] = HW01_problem_07( n )


    array = 2:N;


    for i = 1:length(array)

    if array(i) ~= 0

    for j = i+2: length(array)

    if mod(array(j), array(i)) == 0

    array(j) = 0;




    if array(i) ~= 0

    prime = [prime array(i)];




  • Adindu Iyasara asked a question in Bulk Density:
    What is the difference between Bulk density and Apparent density?

    What is the difference between Bulk density and Apparent density?

  • Luis Federico Gimenez added an answer in Academic Writing:
    How to improve in academic writing?

    Dear RG colleagues, I thank you in advance any suggestions to improve in academic writing.

    Do you also find difficult to write about technical & scientific issues?

    Do you believe that the practice of academic writing is always welcomed to express ideas and concepts in technical & scientific papers correctly, concisely and clearly?

    Luis Federico Gimenez

    Dear  Han Ping Fung, Maria Bettencourt Pires, Georgina Boyd and Sandra Moreira:

    Thank you for your suggestions,

  • Alexander Shtabsky added an answer in Cytology:
    Can cytology replace biopsy?
    In lung cancer can we study slide touch print cytology to prove that the underlying lung mass is a malignant mass, its type and so on? No need for biopsy?
    Alexander Shtabsky

    So, if you have a negative IHC it is negative and for positive you proceed to FISH, correct?

  • James R Knaub added an answer in Accounting Research:
    Does anyone have any experience in publishing an article on peer reviewed journal after uploading it on his/her account on research gate?

    I want to know if it's allowed to publish an article on a peer reviewed journal after uploading it on the personal account of research gate. Anyone has such experience, please share it with us so that we can have an idea about the editors interaction with the uploaded papers on personal account in research gate.

    James R Knaub

    Juan-Esteban, et.al. -

    Double blind review may be best, but still not very helpful.  Each clique has its own ideas and knows who supports what approach.  Consider:  A friend was an author to a paper that was turned down by a 'prestigious' journal recently, likely, it seems, because it used one of two major methods for doing something, and people involved there, at that journal, solely preferred, really required, the other.  That article was then submitted to a more 'prestigious' journal, and approved.  I do not expect this is an isolated incident. 

    In an old case, a friend had an article approved in a journal in 1963, but it was not so heavily scrutinized as in one done seven years later, where people then thought it was a new idea.  Then in the 1970s and 80s, i did development in hypothesis testing, finding it misused, and was lucky to have a letter published on it in The American Statistician in 1987.  Today it seems many more agree with me. 

    More recently, I have had a lot of proven success in model-based sampling and estimation for official statistics for highly skewed establishment surveys, yet many with influence in the world of statistics, but no appreciable experience in using these methods, ignore this. 

    My point is that the system, both in the past, and now, from my experience and others, seems geared to promoting certain schools of thought, at the expense of others, and even a double blind referee process will not stop that roadblock to progress. 

    I have refereed for some prestigious journals, and not so prestigious, and for theses and dissertations, and we all know that the process is far from perfect.  Perhaps double blind reviews are of some help.  But until humans become more open minded and less controlling, we have to know that this is all going to remain problematic.  But I think discussions people have made to this thread are helpful: Always check a journal's policies ahead of time; consider arxiv; use ResearchGate if you aren't concerned about publishing elsewhere.  Also, I think that it is good in general for a question like this to raise awareness.  There is always new hope for improvement with each new generation.

    Cheers - Jim

  • Leonidas A. Papakonstantinidis added an answer in Sensitization:
    Is there any math type for a quanitive measure of the "sensitization process" ?

    The question about the "quantative measurement" of a qualified mean as "sensitization" should be very useful for my research on the "3-win model"

    Leonidas A. Papakonstantinidis

    Dear  Dr. Arghya Ray,

    Thank you very much for your very useful informatio given to me ..

    I'll try to find the book  Intergranular Stress Corrosion Cracking: Final Report of the NKA-Project MAT 530,,,

    I'm very interested on this

    Thank you again for help 

    Prof Papakonstantinidis (GR)

  • Danilo Rastovic added an answer in Entropy:
    Any advice with Fuzzy Shannon entropy for non-equilibrium?

    I am interested to know what will be happened with behavior of fuzzy Shannon entropy for non-equilibrium system.

    Danilo Rastovic

    Fuzzy Gaussian maximizes fuzzy entropy.

  • Mashood Nasir added an answer in Control Systems Engineering:
    Solution Manual Digital Control of Dynamic System 3rd edition
    I'm studying digital control by myself, and I would like to know if has available on the internet the solutions manual of "Digital Control of Dynamic System 3rd edition"?
    Mashood Nasir

    Please email me at mashood.nasir@umt.edu.pk as i am unable to download from the given link.

  • Brian Schwartz added an answer in P Value:
    When the significant differences (P value less 0.05) should be consider as clinical important (seriously) ?

    Are there certain factors could make the statistical significant ( p value less than 0.05) clinically important as larger sample size or randomized controlled clinical studies?

    Brian Schwartz

    I totally agree with all previous writers and want to add one point: When you are talking about clinical importance, maybe you should go in for the reliable change index and the concept of clinically significant change introduced by jacobson and truax (1991).

  • Agostino Prástaro added an answer in General Relativity:
    Universe is static!!! Yes or no?

    Space of Universe is static! Yes or no?

    Question: Are there any observations that do not fit into the model static space of Universe, are there any theoretical obstacles to the existence of such a model?

    I assume that the Universe is eternal, infinite and static, it is not expanded and not curved, it is possible to construct a preferred inertial frame of reference in which the CMBR is most isotropic. The matter in this space evolves, but the average density of matter and energy (in large enough volumes) fluctuate within a rather broad range.
    The light in this model is "tired", the speed of light depends on the optical density intergalactic medium. Gravity is also "tired" t.i. weakens a little faster R2. The energy of destroying matter goes into the surrounding vacuum. The excess energy from the vacuum give rise to new particles of matter.

    I state that all the observed cosmological effects can be explained in such a Static Model of the Universe.
    See attached "Basic_Cosmological_Formula_1_En.pdf"

    Dear colleagues, I do not ask, what are the problems faced by other theories (though I would be interested in your opinion on that. The General theory of relativity is not applicable to the entire space of the Universe).

    Agostino Prástaro

    @ Victor Ostrovskii

    thanks for your last post and your kind evaluations on my person !
    To be considered a 'gadfly' is a great compliment by a 'black sheep'.
    Any user can now well understand the great academic level and scientific content of your attach against me !
    Unfortunately for you the scientific evaluation of a researcher is not counted by the differences between up-votes and down-votes obtained in some RG thread, but by deepness of his scientific works ...
    Furthermore, you cannot consider RG like a your private garden, where you can discuss with your friends ... I disturbed your meeting therein since I did not share your enthusiasm to claim that Einstein's GR is wrong !
    It is impossible to appreciate as scientific arguments such stupidities, without any serious scientific support !
    Furthermore, you have not the authority to say me when I can post my remarks on RG ! Whether you consider that I disturb you, the unique resolution that you can take is do not say more absurdities like ones posted by you until now on RG, against some fundamental science advancements of the last century.

    'Absit iniuria verbis ...'

  • Muhammad Ahsan ul Haq added an answer in Wisdom:
    What is wisdom?

    Philosophic, religious, and opinion responses are acceptable.

    Muhammad Ahsan ul Haq

    Be not afraid of life. Believe that life is worth living, and your belief will help create the fact.
    - Henry James

  • Zainab Issa added an answer in Questionnaire:
    Hi, Could Anyone helps me fill up this Sustainability Questionnaires?

    I really appreciate your help. 

    Link is at below : 


    Zainab Issa

    Done, Good Luck 

  • Simon Eric added an answer in Poland:
    Can somebody provide me a stratigraphic column of Holy Cross Mountains of Central Ppland?

    I'm in need of a stratigraphic column of Holy cross mountains in Poland. I want to have a lithostrat column that displays all rock units in Kielce and Lysogory regions. There are some papers but I could not compile column of each region separately. 

    I would be grateful if someone give me a link or a paper or a map that I can get what I'm looking for. 

    Thanks for your concerns. 



    Simon Eric

    Dear Karwan,

    You can consult mainly for the Frasnian in the Holy Cross Mountains the paper cited hereunder. You shall find in it also a comparison with the Dinant Basin (Belgium).


    Frasnian Gypidulid Brachiopods froms the Holy Cross Mountains
    (Poland). Comparative Stratigraphie Analysis with the Dinant
    Synclinorium (Belgium)
    b y Jacques GODEFROID  and Grzegorz RACKI

    All the best

  • Chilin Shih added an answer in Chinese:
    Pitch normalization

    What is the best method to normalize pitch? I need to compare the L2 tone productions of Spanish learners of Mandarin Chinese with native Chinese children's productions.

    Chilin Shih

    Francis Nolan tested a few methods and recommend semitone in this paper:  http://www.ling.cam.ac.uk/francis/Nolan%20Semitones.pdf

    I use semitone conversion in my paper "Effects of talker-to-listener distance on tone"  https://www.researchgate.net/publication/273889335_Effects_of_talker-to-listener_distance_on_tone

    where I did similar task:  Compare tones across very different pitch ranges, and evaluate why L2 listeners have problem with some productions but not others.  I use polynomial decomposition converting tones to three numbers, then working with numbers are a lot easier than working with pitch contours.

    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: This paper explores the effects of talker-to-listener distance (TLD) on tone and examines its impact on tone perception by both native listeners and second language learners. Speakers naturally change vocal effort to talk to people at a different distance, which leads to changes not only in intensity, duration, formant frequencies, but also in fundamental frequency (f0). F0 is the primary acoustic cue that differentiates Mandarin lexical tones. As it changes as a function of TLD, will that affects tone perception for native (L1) and second language (L2) listeners? If so, what are the changes that have impact on tone perception? The production study reports acoustic correlates of TLD on tone from 7959 monosyllabic Mandarin speech files recorded by three speakers under 11 levels of TLD distance. The perception study explores the effects of TLD on L1 and L2 tone perception from 2 native listeners and 52 L2 listeners. The TLD effects on speech production are orderly and we present models and analyses with sufficient details to simulate TLD effects on tone. Intensity, duration, initial and maximum f0 increase with TLD, while time normalized tone shapes remain invariant. The results of the perception study show that native listener's performance is robust under changes of TLD, while L2 listener's perception of tone interacts with TLD. One significant finding is that tone 3 recognition improves with TLD. The work investigates the relationship between speech production and perception when acoustic attributes change naturally in response to the demands of speech communication. The results can find applications in speech synthesis, pronunciation training and second language testing.
      Full-text · Article · Mar 2015 · Journal of Phonetics
  • Charlton Aigbekaen asked a question in Archiving:
    I need to know more about research script irm4716?

    Information Resource Management (IRM) is a philosophical and practical approach to managing
    information. Information is regarded as a valuable resource which should be managed like other
    resources, and should contribute directly to accomplishing organizational goals and objectives. IRM
    provides an integrated view for managing the entire life-cycle of information, from generation, to
    dissemination, to archiving and/or destruction, for maximizing the overall usefulness of information, and
    improving service delivery and program management.
    Identify an IT industry technology-oriented research problem, (mainly caused by lack of proper IRM) by
    describing and analyzing the research problem, showing gaps through a rigorous literature review,
    formulating objectives, research questions and hypothesis. The research problems can include to:
    investigate different existing models to diagnose network failures; identify the shortcomings of network
    models, database systems, service functions, operation processes, or/and software development
    To carry out the research work above, answer the following questions:
    1.1. Give a brief description which introduces the research problem to be investigated. [10]
    1.2. Formulate the research problem statement. [5]
    1.3. Formulate the hypothesis of your research problem. [5]
    1.4. Formulate the objectives of your research work. [5]
    1.5. Formulate the research questions. [5]
    1.6. Write a complete literature review by analysing critically, comparing and evaluating scholarly works
    related to the problem to be investigated. [20]

  • Stam Nicolis added an answer in Conservation Laws:
    What happens to a 'linear' polarized photon when passing throught a dichroic crystal?

    Dirac said that a 'linear' polarized photon is a superposition of left and right rotating photons. Here is a puzzling aspect of this superposition.

    There are dichroic materials which can absorb only left photons. What is their effect on this superposition? They would absorb the left state and let the right. It turns out that there are two photons in a 'linear' photon! The mechanical momentum of the dichroic material must be measurable in principle  (like Beth experiment). It would be expected that there is some energy hv absorbed too but it must be in the right photon also. Conservation of energy seems broken? If there is no momentum and no energy absorbed in the dichroic the conservation laws are also severely harmed. At least something happens to that photon (linear to right which is easy to show) but nothing happens to the causer of this event (namely to the dichroic). I see that there must be wavefunction collapse for the photon and in fact the question boils out to:

    Is something physically happening to the machinery causing the collapse?

    This question is connected to the following question:

    Is there any way to split a linear polarised photon into left and right polarised photons? - ResearchGate. Available from: https://www.researchgate.net/post/Is_there_any_way_to_split_a_linear_polarised_photon_into_left_and_right_polarised_photons [accessed Feb 12, 2016].

    Stam Nicolis

    A linearly polarized photon is a superposition of circularly polarized photons. The effect of the medium is to project out one circular polarization, leaving the other. Absorption *means* that the medium gains that amount of energy-so when the remaining circular polarization is projected back in the linear polarization basis, the total energy is, of course, less. It suffices to compute the sum of the squares of the absolute values of the coefficients, that, as standard textbooks in electromagnetism review, represents the energy of the wave in question and the same holds in quantum mechanics, as reviewed in Feynman's lectures.  This stuff is taught in undergraduate physics courses. 

  • Hani S. Mahmassani added an answer in Car:
    What do you think about the self-driving cars, will they be mostly private or public / shared transportation?

    Self-driving cars are one of the major technological trends for the near future. However it is not clear if private users will have their own self-driving car or will they become a public service or mostly for shared usage by companies like uber, lyft and others.

    Hani S. Mahmassani

    All of the above.  I paste below a section excerpted from a recent chapter I have written.

    The emergence and adoption of autonomous vehicles is expected to accelerate certain trends already underway in terms of shared urban mobility, and to enable new mobility service models that bridge traditional transit service and personal mobility, resulting in new hybrid forms....These potential changes in the supply of transportation and mobility at the urban scale are difficult to predict and characterize for the purpose of developing specific planning tools, and forecasting the demand for these services over time.  

    While it may be difficult to predict exactly which services may emerge in a certain locale, and the extent and type of demand these might serve, the following aspects can be noted based on current understanding of travel behavior and the expected features of autonomous vehicles.

    a.    It is a given that driverless vehicles will enable new forms of mobility supply.  By eliminating the cost and performance limitations of human drivers, and increasing the ease of communicating instructions to both vehicles and travelers, autonomous vehicle fleets can be operated efficiently to deliver dynamically scheduled services to individuals riding privately or in shared vehicles.

    b.    New forms of car sharing with greater convenience may reduce the motivation for individual ownership.  With driverless cars, availability of a vehicle in sharing services such as Zipcar and Enterprise car share (formerly Igo) is not limited to the nearest lot. Vehicles can be repositioned dynamically to the user’s location from anywhere in the city.

    c.     Ride and car sharing marketplaces will likely expand with driverless vehicles, following, for example, platforms developed by ride-hailing app companies like Uber and Lyft.  This would contribute to reducing the cost and uncertainty of the sharing model by increasing the supply pool and enabling rapid dispatch of driverless vehicles.

    d.    The realm between personal transportation and public mobility can widen considerably to include various hybrid forms.  Many agencies have already embraced a spectrum or suite of services in order to reduce operating costs in lower-density metropolitan areas. Experimenting with a fleet of smaller vehicles, casual sharing, and more traditional vanpools and guaranteed ride home programs, agencies have explored many options to move people over low-density areas or at odd times of day. Services in this spectrum, which fall between purely fixed-route and purely demand-responsive and can be described as “semi-flexible”. These services typically include a set of stops with a predetermined schedule along with sections of a service area where service is flexible (e.g. route deviation), possibly with door-to-door service. The premise of these services is that in low-density areas, certain points will have higher demand at different times of day (e.g. hospitals, dedicated guideway transit, major employment/retail centers). Imposing some structure, but still allowing flexibility, can create more efficient tours while remaining intuitive and user-friendly.  With autonomous vehicles, greater dispatching flexibility is possible, enabling the equivalent of personalized service at times, and shared rides at others, depending on the specific demands prevailing at a certain time.

    e.    What will become of public transit as we know it?   With transit companies adopting a broader portfolio of services, possibly in conjunction with third parties, one could envision disappearance of conventional fixed-route, fixed-schedule bus service in most lower-density communities, supplanted by driverless, personalized service at low density and shared hybrid forms at medium densities; and greater focus on frequent rapid service along dedicated right of way (rail and/or BRT) in higher-density travel corridors, made more efficient and accessible via driverless hybrid options.

    Some of these trends are beginning to emerge today.  Several communities are experimenting with hybrid forms of public transit. Car sharing programs are thriving in many cities.  Ride-hailing app companies (Uber, Lyft) that dramatically increase the pool of available vehicles to serve customer requests (albeit on still controversial regulatory grounds) have become household names in many cities around the world.  Some of these same companies, especially Lyft, are making a concerted effort to tailor services to better complement existing transit services by, for example, providing access to rail transit stations (e.g. http://take.lyft.com/friendswithtransit/, accessed December 21, 2015).  In Finland, the city of Helsinki received a lot of attention in transportation planning circles when it announced its goal of no more private car ownership in the city, all the while while offering individual and shared public personal urban mobility through a city-managed virtual platform.  

  • Joshua Coulson asked a question in Climate:
    Any motivational climate questionnaires?

    Anything at all related.

  • Stam Nicolis added an answer in Mathematical Physics:
    Is Lagrangian, depending only from coordinates minus full system energy?

    If do, can we consider any function of coordinate as minus some physical system energy? Moreover, if we have infinite number of coordinates (like scalar field), energy will be minus integral of Lagrangian density and can be infinite. Can we say, that such configuration is physical?

    Stam Nicolis

    If there aren't any velocities, the system is just constraints. But it doesn't make any sense speaking of a Hamiltonian, or an energy,  since that is the generator of time translations, that are absent. 

  • Spyridon Alexandros Petropoulos added an answer in Lamiaceae:
    What is the best medium for seeding and transplanting wild plants?

    Regarding family Lamiaceae, what is the best medium for seeding and transplanting wild plants?

    Spyridon Alexandros Petropoulos

    You can mix it with peat moss having low pH.

  • Kadhim Hubeatir added an answer in Materials Processing:
    What is the meaning of the term ''meta'' in some solid structure?

    For instance, Lithium Metatitanate and Lithium titanate, Batium titanate and Barium Metatitanate.

    Kadhim Hubeatir

    I think means the compound consist from hybrid material or semi


  • Leonid V Vladimirov added an answer in Epoxy Resins:
    Why 2 part epoxy resin even after 48 hrs of curing remaining in gel form and not solidifying?

    I tried making composite out of Araldite CY-230 epoxy and HY-951 hardener. But it is remaining in gel form and not solidifying. What may be the possible reason?

    Leonid V Vladimirov

    The solubility of Hardener is usually rather slow. Actually in epoxy-hardener system a much better solvent for hardener is the product of the initial stages of reaction (induction period). Basing on these facts I propose to introduce the hardener in several portions. This approach in my opinion will result in fully cured solidified material.

    Regards,                           Leonid

  • Manar Magdy Farouk(Manar M. Farouk) added an answer in Bacterial DNA Extraction:
    What is the best method for Bacterial DNA extraction from feces without using commercial kit?

    please i need to know what is the best method for Bacterial DNA extraction from feces because there is no availability for commercial stool DNA extraction kit.

    Manar Magdy Farouk(Manar M. Farouk)

    Thanks alot Dr. Rangsun 

  • Rabie L. Abdel Aziz added an answer in Image Analysis:
    Computerized image analysis, any help?

    Trying to count ovarian antral follicular populations, I need to know more about co image analysis.

    Rabie L. Abdel Aziz

    Hi John,

    Thank you so much for your answer. I will do ASAP.

    Best regards,