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  • Valentin Danci added an answer in Gravitational Field:
    Is the non locality of the gravitational field energy a serious problem for General Relativity (GRT)?



    "Although there is no room for such a thing in the energy–

    momentum tensor T, it is clear that there are situations where a ‘disembodied’

    gravitational energy is actually playing a physical role.

    Imagine  two massive bodies (planets, say). If they are close together (and we can

    suppose that they are instantaneously at rest relative to each other), then

    there will be a (negative) gravitational potential energy contribution which

    makes the total energy, and therefore the total mass, smaller than it would

    be if they are far apart.  Ignoring much tinier energy effects,

    such as distortions of each body’s shape due to the gravitational tidal field

    of the other, we see that the total contributions from the actual energy–

    momentum tensor T will be the same whether the two bodies are close

    together or far apart. Yet, the total mass/energy will differ in the two cases,

    and this difference would be attributed to the energy in the gravitational

    field itself (in fact a negative contribution, that is more sizeable when the

    bodies are close than when they are far apart)." 


    The same problem was also rised by Thirring, Kalman and Feynman in the FGT theory, they inserted the gravitational energy in the tensor equations...

    It is a problem of paramount importance which prevents the General relativity theory from describing any motion in which the hamiltonian is time dependent or rather in case of non isolated systems, or in case of non stationary interactions between different bodies.

    The attempt to model a free falling body in a gravitational field for GRT seems impossible.

    GRT has been tested  only for static or stationary systems where there is not a net exchange of energy (excluding gravitational radiation)

    Don't we need another GRAVITATIONAL THEORY which includes the results give by GRT in order to explain with a better accuracy the simple phenomenon like the free falling of a mass in a gravitational field?

    Valentin Danci

    Luiz C. L. Botelho wrote:
    "Dear Azzam [...] but remember Special Relativity is better applied to the world of elementary particles-if not only to the elementary particles  .There , there is not rigid bodies , etc....All pictorial arguments used by Einstein with bodies leads naturally to paradoxes , they are without any rigor ."

    I am so glad that a relativist admits the paradoxes resulted from Einstein's STR demonstrations.

    The question is, which other demonstration of STR does not lead to paradoxes, and also, which demonstration of STR was done by using mainly elementary particles *instead* of rigid bodies?  I haven't heard of any such demonstration, and frankly I don't think it is possible.
    (I am hoping nobody invokes the picture of an elementary particle moving on a world line as a demonstration for STR - because such a picture is literally rubbish from a reasoning perspective, and it's worse than Einstein's faulty reasoning.)

    "Think special relativity as the problem of determining   mathematically precise those  laws of coordinate transformations among inertial "Newtonian" systems which preserve the spherical form of the equation of the light motion."

    Who demonstrated that "the spherical form of the equation of the light motion" needs to be preserved? Nobody. It's just a guess, a horrible assumption of the present-day relativists. On the contrary, Einstein himself wrote in 1905:

    [...] a spherical surface moving with the velocity of light [...] The spherical surface―viewed in the moving system―is an *ellipsoidal* surface".

    Of course that is another contradiction in STR, carefully hidden by the relativists now, as they are much more preoccupied to juggle around with their fantasies about manifolds and fiber bundles.

  • Akshay Wanjale asked a question in Affect:
    How will a well graded aggregate affect the amount of water used within a mix?

    how does it affects 

  • Jehad M. Nasereddin asked a question in Writing:
    I know this is more of a literary than a scientific question, but I need help in this endeavor?

    What should I take into consideration when I'm writing a paper? Things to do before publish and how to improve the quality of my writing?

  • AnneMarie McEvoy Conley added an answer in Latent Class Analysis:
    Do you know any theoretical and/or empirical application of the so called person-centered analysis (e.g. clustering, LPA) to dyadic data?

    Person-centered (or person-oriented) approach – in contrast to variable centered one – is more and more frequently used to analysis of individuals, e.g. personality traits. Did you meet any theoretically based papers and/or empirically sound studies where this analytical toolkit (e.g. various clustering methods, Latent Class Analysis and Latent Profile Analysis) was used for DYADIC data? Dyadic data is commonly analyzed by Actor Partner Interdependence Model (APIM) which is clearly a variable centered method. May be there examples of an alternative pattern oriented approach? How can these kind of results be interpreted? Any hints are highly appreciated!

    AnneMarie McEvoy Conley

    OK. I understand a bit more now. We do similar kinds of analyses with individuals and classrooms. One way is to cluster (or LPA--quite similar when specified the right way) at the level of the individual and then cross tab the partner 1 and partner 2 clusters. Where are the white spots and dark spots in the data? Are there particular pairings that are more common (statistics would be like a chi sq, testing whether the adjusted standardized residuals are greater than one would expect if the pairings were due to chance alone).

    I think the Bergman et al. book will help you a lot (Studying individual development in an interindividual context: A person-oriented approach. L R Bergman, D Magnusson, B M Khouri). They use their freely-available SLEIPNER (which is the way I learned to do cluster analysis) with a set of modules for testing and comparing different cluster solutions, imputing missing data,  etc. Note that MPlus is also my go-to package, but the questions you are asking about theory don't require any particular package to run. They also aren't new, though they're certainly advanced. I linked below to a paper I wrote using clustering with SLEIPNER. I can send it to you directly if you can't get the full text. Just message me for it.

    There are a few publications by Steve Peck who is a genius at thinking about these multiple levels of analysis. My favorite is "TEMPEST in a Gallimaufry: Applying multilevel systems theory to person-in-context research." The reason you haven't found much done in this area is because most of us are still working it out and I, for one,  am not comfortable publishing results from this person centered work until I have been able to replicate and test my findings across different samples and talk with others doing similar work about different ways to tweak the methods to get at the question. When it comes to getting support from the Muthens for work in Mplus, their responsiveness is quick and helpful on the stat model boards. 

    • [Show abstract] [Hide abstract]
      ABSTRACT: A person-centered approach integrated achievement goal and expectancy-value perspectives and identified patterns of mastery and performance-achievement goals (developing vs. demonstrating competence), task values (beliefs about interest, utility, importance, or opportunity costs), and competence beliefs. Cluster analysis classified 1,870 students (primarily Vietnamese and Latino) taught by 40 teachers in 148 math classrooms in 7 urban middle schools. Seven patterns were identified. In one adaptive pattern, students reported moderate interest in math and a sole focus on mastery goals of developing competence, supporting a traditional perspective on how goals operate. In another, students focused on both developing and demonstrating competence, supporting a multiple goals perspective. Achievement and affect did not differ significantly between these 2 groups, though both fared better than a 3rd cluster focused also on avoiding the demonstration of incompetence. Across all clusters, cost value differentiated more- and less-adaptive patterns of motivation. Integrating goal and value constructs improved prediction of affect and achievement and indicated that linear models may mask complex interactions. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
      Journal of Educational Psychology 01/2012; 104(1):32-47. DOI:10.1037/a0026042
  • Maria C Villacres added an answer in Flow Cytometry:
    Unspecific stimulation with PMA + ionomycin vs. PHA for intracellular cytokine staining of T cells
    I am trying to compare cytokine production (gamma interferon and TNF alpha) by T cells in different patient populations, looking for functionality versus exhaustion. As I do not have a specific antigen available, I am stimulating the T cells with PHA or with PMA + ionomycin before Golgi stop. However, these two protocols give qualitatively different results for the comparison of my populations. Can anybody advise me which stimulation protocol is more suitable and significant, and what is the difference between the cells activated by these two stimulants?
    Maria C Villacres

    Krupa, the CD3/CD28 stimulation is pretty potent. Adding additional stimulation may overload the cells. If long enough, they would die off. Safer to be careful with this approach.

  • Debra Sharon Ferdinand added an answer in Team Working:
    How do you approach the design of a group task in higher education?

    "Team work" is a requisite graduate attribute for most, if not all, universities across the world. Skills related to team work are embedded in group tasks that are intended to mimic or be a real-life work problem/task. How do you approach group task design in higher education to ensure the necessary team work skills are attained? How do you measure the three interrelated processes of task, team, and relationship?

    Debra Sharon Ferdinand


    I wish to endorse your comments above as it appears that we take it for granted that students acquire these group skills along their educational journey, only to find that they struggle to orient the assigned group task successfully to the end. Indeed, we need to ensure that they have the required soft-skills set to engage in group work.

    Many thanks,


  • Muhammed oda Mallah asked a question in Ectoparasites:
    Can any one help me to diagnosis of ectoparasites samples that i found on long ear hedgehog ?

    ectoparasites samples.

    + 9 more attachments

  • Raymond W. Wong added an answer in Gene Expression Studies:
    Which assay should i use to validate my gene expression study of glucose handling genes, immunohistochemistry or western blotting and why?

    genes like InsR, RBP4, GLUT1, GLUT4, PGC-1

    Raymond W. Wong

    To add to the above, an ELISA will give you the concentration (e.g. ng/mL) of your target protein in your sample taken.  

  • Felipe Gil-T. added an answer in Butterflies:
    Did artificial diet affect Troides helena female to produce male in their offspring?

    In my research, I just find Troides helena male coming from artificial diet containing red bean, pollen and mung bean sprout. In contrast, natural food produces male and female butterfly. 

  • Muhammed oda Mallah asked a question in Ectoparasites:
    Can any one help me to diagnosis of ectoparasites samples that i found on long ear hedgehog ?

    ectoparasites samples.

    + 3 more attachments

  • Ercan Kocayörük added an answer in Time Perspective:
    Is there any literature on Time Perspective Psychotherapy?

    CAn anyone help me on the literature about time perspective therapies. I found Zimbardo's Time perspective studies ..I could not find enough papers and studies...Does anybody recommend me any paper and study?

    Ercan Kocayörük

    Dear Friends 

    Thak you so much

  • Isabel Garcia added an answer in Conservation and Restoration of Cultural Heritage:
    Does anyone have any bibliography on the outcomes or long term results of heritage reconstruction projects?

    I'm interested in evaluating how the original criteria that substantiates a heritage reconstruction project (after a natural disaster or warfare) turn out in reality.
    I would like to identify, among other things, if these projects actually contribute to social healing/rehabilitation or to the development of the area, and if they are successfully linked to the community. And if not, to identify what unforeseen factors were involved in the project that prevented the initial objectives from being met.

    Isabel Garcia

    This issue just came out about the recovery from the earthquake of the city of Lorca, Spain. It might be of your interest.

  • David T. Risser added an answer in Ethical Analysis:
    Which influential ethical theorists claim that inter-subjective attunement (sharing affective states with others) is necessary for morality/ethics?

    I'm looking for influential thinkers who argue that intersubjectivity is necessary for being moral and/or living a good life. Ideally I want to find examples of well-known analytic, continental, and feminist thinkers who hold this view. Thanks so much!

    David T. Risser

    Dear Robert,

    To more directly answer your original question, may I suggest Carol Gilligan's book, In A Different Voice, (Harvard U. Press, 1982)?  This book contains an influential feminist critique of Kohlberg's stages of moral development.  Central to Gilligan's own account of morality is the value of caring.


  • Rami Alrezk added an answer in Logistic Regression:
    What should be the minimum sample size for running logistic regression?

    May I use Logistic regression Model with 200 sample size (100 organic farmers + 100 Conventional farmers). Dependent variable is "Adoption of organic farming (Yes/No) or (Organic/Conventional)" with seven Independent variables in five point scale ranging from Strongly Agree to Strongly Disagree. The objective of this study is to examine the influence of 7 different economic (Independent) variables in adoption of organic farming. 

    Rami Alrezk

    Agree with all the above, it is very complicated yet it can be simplified in a simple rule for sample size in running logistic regression; 

    the rule of thumb is that you need at least 10 for every variable you add to the model; 

    so looking at your sample size and having 7 variables; you could run the model. 

    good luck in your research 

  • Landon W Locke added an answer in Immunology Techniques:
    How do I enhance surface expression of FPR1 on primary human neutrophils?

    I want to titrate my rabbit anti-human FPR1 antibody and would like to perform the titration on cells that I know strongly express FPR1 on their surface.

    Landon W Locke

    Thanks Mahendra.  After reading some older papers, I think I will choose 50ng/mL PMA for neutrophil stimulation for 5 min at 37C.  PMA seems to increase surface expression of the FPR.

  • Soledad Miranda-Rottmann added an answer in Mitochondrial Biology:
    Can someone recommend the best markers for mitochondria?

    Can someone recommend the best markers for mitochondria?

    Thank you

    Soledad Miranda-Rottmann

    Mitotracker (which I have used) is great in living cells. Unfortunately the signal-to-noise ratios are high in fixed tissue. The Molecular probes people recommend using anti-OxPhos antibodies  (for example, Cat # A21355) is a good option. (see link below) 

  • Ashley Mills asked a question in Group Therapy:
    What are potential limitations of doing group therapy with Native American clients?

    On the flip side, what are some of the potential benefits?

  • Levan Tielidze added an answer in Water Resources Engineering:
    Is there any good book or study materials on Applications of Pattern Recognition and Machine Learning in Hydrology and Water Resources Systems?

    I am looking for the materials where applications of methods in statistical learning in hydrology is explained.

    Levan Tielidze

    Hi, maybe you look this link 


    Also I have attached "Word file" for you

  • 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.

    Marc Tessera


    "My working definition of consciousness proposes that a supra-threshold activation of retinoid space in a normal brain is necessary and sufficient to constitute a state of consciousness. In experimental tests of the retinoid model, it was successfully demonstrated that vivid hallucinations, predicted by the model, could be reliably induced in normal subjects".

    Well, I thought you would give us a personal reference showing that, in accordance with your retinoid theory, S* should be consciously perceived in the priming experience.

    Is there such a reference?

  • Xiting Liu added an answer in Bathymetry:
    Does anyone have a detailed bathymetry map of the Rufiji River mouth (Tanzania)?

    I want to know whether my research site (red star in attached figure) is located in or out of the canyon system.

    Xiting Liu

     Dear Tielidze, Thanks, it is a nice map. 

  • Alejandra Castro-Chong asked a question in Thermal:
    Is it possible to flatten the FTO surface on TEC substrates by chemical or thermal means?

    A compact layer of TiO2 is to be deposited on top.

  • Monica Yiyun Jiang added an answer in 293T:
    Why could I not see protein overexpression even if the mRNA increases?

    There's an overexpression experiment that is driving me mad.

    I'm trying to overexpress a protein in HCT116. I've cloned the cDNA and tagged it with a Flag sequence to detect it (the antibody for the protein is awful, so I want to use antiflag to be sure). The whole construct has been sequenced and there are not stop codons or mutations. I've checked that the codon usage and it's correct also.

     In 293T transfected transciently, the construct is expressed and detected with the antiFlag antibody by western blot nicely. In HCT116 I couldn't dectect the protein neither with stable or non stable transfection (in all the cases, I've made a control of GFP and the efficiency of transfection was about the 70% or more).

    Moreover, by qPCR, I can see that the expression of the construct increases 10 folds in my cells transfected but in despite of this, I could not detect the protein with the antiflag (I always put controls for the antiflag antibody with and old construction that I have and it's not a problem of the antibody but my sample). I use 40ug of protein for western blot, so I don't think that is a problem of the protein amount.   

    I even change the plasmid of overexpression from pMSCV to pBABE with the same results.  Any suggestions? Thank you in advance!

    Monica Yiyun Jiang

    Hi Yaiza, from my exp, the promoter may cause problem, is you interested protein and flag under the same promoter?  as different promoter express level different in different cell lines (so many different ; )), if your interested protein under a promoter working in HCT116, but your flag promoter not working, then its possiable you can get your protein but not flag. As for 293 cells, they were almost working in all promoters, so you can get good results from it. 

  • Rafik Karaman added an answer in DFT Calculations:
    Is it better to use unrestricted DFT or a combination of restricted and restricted open shell DFT to calculate redox potential?

    Hello everybody

    I am trying to calculate redox potentials of technetium complexes using DFT.  I have to optimize the structures of the reduced and the oxidized species and then from a frequency calculation it is possible to obtain thermodynamics properties like ∆G and with this the redox potential. When I optimize the structures, the oxidized species have a paired number of electron but the reduced species have an unpaired number of electron so I have to use restricted open shell or unrestricted calculations to do it.

    My question is, is it better to calculate all the structures (oxidized and reduced species) with unrestricted methodology or to calculate the oxidized species with restricted and the reduced with unrestricted or restricted open shell? Are the results comparable?



    Rafik Karaman

    Dear Daniel,

    The conclusion of my previous message is to use UB3LYP since the unrestricted calculation using DFT does NOT produce spin contamination.


  • Mario Stipčević added an answer in Optics:
    What is the fundamental information required from an light field image to determine or estimate its depth information?

    Hi all, i have read some literaure on light fiield depth estimation and it seems most of them use either resolution information or shading as a parameter to obtain or estimate depth of the scene. Are there other methods that are accurate or that could be used to estimate depth in a scene?

    Mario Stipčević

    Depth is a very funny word in English and can have unexpected usages and meanings. Assuming that you mean distance between the eye and an object in the field of view (scene), of course the most straightforward way camera can o it is by measuring the time that light travels to and fro a piece of a scene, just like with a RADAR. This is called 3D LADAR, google it. 

  • Hend A. Malhat added an answer in Impedance:
    How do I calculate the shottkey diode input impedance using ADS in rectifier circuit?

    i want to calculate the diode HSMS-8101 input impedance to be 22-j20 for 1000 ohm load and 50 ohm source and 10 mW input power using ADS listed in the reference paper is (A compact and wideband circularly polarized rectenna with high efficiency at x-band).

    or the methods used in ADS to calculate the diode impedance.

    Hend A. Malhat

    you are right Remi Cornwall, but this diode will be a part of total rectenna system which should be accurately modeled using ADS to be correctly matched in the circuit. so i asked for help in ADS design. 

  • Azzam K Almosallami added an answer in Invariant Theory:
    Did Einstein obtain field equations directly from the principle of equivalence?

    "THE MEANING OF RELATIVITY” is a description of General Relativity by Einstein.


    Einstein wrote: "It is evident that the formulation of the general theory of relativity assumes a generalization of the theory of invariants and the theory of tensors; the question is raised as to the form of the equations which are co-variant with respect to arbitrary point transformations. The generalized calculus of tensors was developed by mathematicians long before the theory of relativity. Riemann rst extended Gauss's train of thought to continua of any number of dimensions; with prophetic vision he saw the physical meaning of this generalization of Euclid's geometry. Then followed the development of the theory in the form of the calculus of tensors, particularly by Ricci and Levi-Civita. This is the place for a brief presentation of the most important mathematical concepts and operations of this calculus of tensors". Page 68.

    Many have claimed that in 1915 Hilbert discovered the correct field equations for general relativity before Einstein but never claimed priority. Following article shows that this view is in error.

    Belated Decision in the Hilbert-Einstein Priority Dispute

    According to the commonly accepted view, David Hilbert completed the general theory of relativity at least 5 days before Albert Einstein submitted his conclusive paper on this theory on 25 November 1915. Hilbert's article, bearing the date of submission 20 November 1915 but published only on 31 March 1916, presents a generally covariant theory of gravitation, including field equations essentially equivalent to those in Einstein's paper. A close analysis of archival material reveals that Hilbert did not anticipate Einstein. The first set of proofs of Hilbert's paper shows that the theory he originally submitted is not generally covariant and does not include the explicit form of the field equations of general relativity.


    If equivalence principle was origin of general relativity, how Einstein have obtained Field equations?

    Azzam K Almosallami

    DEAR Hans van Leunen,

    Have you thought in Zeno's paradoxes and how he described the motion? I think the motion according to the wave-particle duality is very near to what described in zeno's paradoxes.

  • Abhilash Sugunan added an answer in Fourier Transform:
    Fourier transform of AFM images - what does FTT show?

    Got a lot of ideas and/or information according what FT of AFM/MFM images shows. For instance: the directionality of magnetic field, elongation of domains, etc. According to another scientist it is not so obviously. So, is there any paper where exactly/clearly explanation/interpretation of what FT picture presents?

    Abhilash Sugunan

    If your real image has periodic features for e.g. rows of lines or dots, irrespective of their physical origin, the FFT images will have features (spots, arcs or even circles) with certain radii and angle from the center. Just download a free software (e.g. ImageJ http://imagej.nih.gov/ij/download.html) and then just start doing FFT of certain parts and look at the FFT patterns. Another very useful tool that you can use with such softwares is the 'inverse FFT' to get back the real image.

  • Ihsan Ates added an answer in Pulmonary Embolism:
    What is the most reliable marker in the differential diagnosis of pulmonary embolism and community-acquired pneumonia?

    Because of similar clinical manifestations and laboratory findings, differential diagnosis of pulmonary embolism and community-acquired pneumonia (CAP) is generally difficult. 

    Ihsan Ates

    I think these are not the best

  • Raymond W. Wong added an answer in Hela Cells:
    What if I incubate hela cells in PBS?

    Hi to all,

    I need to incubate a plate of hela cells in a solution of PBS (without Mg and Ca). Is it dangerous? do PBS cause detachment or morphology changes of the cells if I incubate them for 30 min in this buffer at 37 °C?

    thank you

    Raymond W. Wong

    I am not sure what your application is exactly. I routinely wash and have them in PBS at RT for 30 min-1 h for cell scans. They will begin to round up after 30 min and start detaching after 45 min or so.  I don't have any downstream issues even after an hour when harvesting for protein/RNA analyses. I did leave some out for >2-3 hours but won't know the answer until a few weeks from now. I have not tried to add Mg+/Ca++ to help them stay attached but have added 7% FBS-PBS which helped maintain morphology/attachment over 30-45 min, if i recall correctly. Hope this helps!