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  • Nai-Kei Wong added an answer in Gossypium:
    How can I induce mutations in mitochondrial genome for induction of cytoplasmic male sterility?

     The crop of my work is Gossypium hirsutum. Can anyone please suggest me the Physical & chemical mutagens that can induce mitochondrial mutations leading to cytoplasmic male sterility. Please share me the protocols /links/literature/suggestions. Waiting forward for your kind replies.I wanted to induce mutations in mitochondria for induction of new source of cytoplasmic male sterility which will helpful for hybrid seed production

    Nai-Kei Wong · The University of Hong Kong

    From casual discussion with a friend working on plants, it seems very strong light is enough a source of mutagenesis. 

    This review here states that gamma rays are mutagenic. 


    In addition, a number of antibiotics have been used:



  • Bagonza Joseph asked a question in Uganda:
    What is the current trend of drug resistant Tuberculosis in Uganda?

    Hello researchers am trying to find out the current trend of drug resistant TB in Uganda based on your observations and experiences.

  • Theo K. Dijkstra added an answer in Likert Scale:
    Should independent factors significantly correlated with independent factor to enter them to Partial Least Squares modelling?

    Dear Colleagues... I am using Partial Least Squares (PLS) to predict student satisfaction (7 point Likert scale (1: strongly disagree to 7: strongly agree)), one of the independent factors in the model is gender diversity (1: male, 2: female). Firstly, I used Pearson correlation to find if there is a correlation between independent factors (e.g. gender) and dependent factor (e.g. satisfaction). The results showed that there is no significant correlation between gender and satisfaction.

    My question is: Should I enter this factor (gender) to the model as other independent factors even if it is not significantly correlated with the dependent factor or should gender be excluded from the model.

    The number of independent factors is 6.

    The number of observations is 70.

    Many thanks

  • Elham Kowsari added an answer in Extended Kalman Filters:
    TOF positioning with extended kalman filtering?

    Hello, TOF range is used in the wireless sensor network, to join the extended kalman filter for reducing error, EFK state vector and the measurement of vector can freely choose?I turned out to be the reference published literatures, this set of x_k = (x, vx, ax, y, vy, ay) y_k = (r1, r2, r3 and r4), r the distance of moving point to four stations.Transfer matrix A is 6 * 6, measurement matrix H is 4 * 2, found that when debugging to dimensions of the matrix is not in conformity with the problem, please how to solve?

    Elham Kowsari · Shiraz University of Technology

    The EKF can be
    difficult to tune and often gives unreliable estimates if the system nonlinearities are
    severe. This is because the EKF relies on linearization to propagate the mean and
    covariance of the state.

  • Ayuob Aghaei added an answer in Graphene Quantum Dots:
    What is the best method to drying graphene quantum dots?

    I have 20 ml water solvent containing graphene quantum dots and sodium salts. How do I prepare GQDs powder so it’s preserve the crystalline nature? I dried it in 1000C temperature but XRD spectrum show non-crystalline GQDs.

    Ayuob Aghaei · University of Tabriz

    But I haven't freeze drying equipment. do you know the other method?

  • Patrick Druggan added an answer in Encapsulation:
    Which kind do I need to simulate of buffer needed the lactic acid containing food solution?

    I would like to simulate the liquid media used for releasing test of my encapsulated particles. The prospective system is the lactic acid fermented food products. Which kind of buffer (which have to contain the lactic acid and at pH 4.5) is preferred?

    If I use the other buffer systems like citrate-phosphate or citrate-sodium citrate buffers and add lactic acid into these buffers, does it represent the lactic acid containing-food liquid? or should I use lactic acid-sodium lactate buffer instead of them? Which one is the best represented lactic acid-containing food liquid system?

    Patrick Druggan


    That link is broken

  • Otto E. Rossler added an answer in General Relativity:
    Can someone help or explain how to derive a field equation that preserves 1/r potential instead of 1/r^2 acceleration?

    The Schwarzschild metric coefficient, or time dilation factor, is (1-2GM/Rc2)-1/2.  This is found by solving the Einstein field equations for a point mass. The effect of this particular coefficient is to preserve the inverse square law of gravity for a distant Schwarzschild observer, exactly, even for strong fields.  See working paper linked below for details.

    In so doing, it does not preserve the 1/r potential.  Modern field theories might well be more able to handle and explain a potential law as a source of gravity more easily than an inverse square law.  (1+GM/rc2) would preserve exactly the potential law, and is indistinguishable from the Schwarzschild coefficient in all gravitational experiments to date, or even those conceived in the near future.  I would like to explore this, and the purpose of this question is to engage knowledgeable collaborators who can help figure out how to construct a field equation which when solved for a point mass gives the potential law preserving solution rather than the inverse square law solution.

    Otto E. Rossler · University of Tuebingen

    Dear Rob:

    Don't allow youself to be pulled away from simple geometric thinking. Very few are as able as you are in the method that alone counts. Such children's math questions start way too late.

    Take care,


  • Ibrahim Shnawa added an answer in Young People:
    Would it be meaningful to measure the Immune Risk Phenotype in young people? By meaningfull I mean would it predict current and future sickness?

    For example:

    Faragher, R., Frasca, D., Remarque, E., Pawelec, G., & ImAginE Consortium. (2014). Better immunity in later life: a position paper. Age, 36(3), 1041-1048.

    Ibrahim Shnawa · Al-Kasim Green University , Babylon

    Please find herewith the followings;

    i-Siegrist C-A, Aspinall R,2009.B cell responses at the life extremes,Nature Immunol,9,185-193.

    ii-Breitbart E,Stollar, 2000,Ageing and the human Immune system,IMAJ,2:703-707.

    iii-Arture J,2008,Theories of Immunosenscence and infection, J.Biomed. Therap.,2(3):16-19.

  • Arkady Kholodenko added an answer in Path Integration:
    Had somebody seen quantum mechanical calculations for the particle in an arbitrary triangle?

    Had somebody seen quantum mechanical calculations for the particle in an arbitrary triangle or, say, in an arbitrary pentagon? Have you seen the path integral solutions for such configurations? What use one can make out of these solutions?

    Arkady Kholodenko · Clemson University

    I had in mind the connection with billiards. Particle in 1d box is the simplest example discussed in any textbook. However, nobody dared to mention in these textbooks that the problem becomes instantly too complicated for billiard configurations. And yet, the system is still Hamiltonian and can be looked upon as either  mechanical, or as optical or as quantum mechanical. Equilateral triangle should be solvable group-theoretically if the boundary conditions are appropriate. If the triangle is not equilateral, the situation is much more difficult and, quite frankly, I am not aware of any closed form solutions. Still, I brought this example just to demonstrate how badly modern textbooks on QM are written....QM should be discussed by analogy with 1d box ONLY in the case if in such billiards are closed trajectories.This is the crux of the matter. This issue then will slide into the issue of existence of closed geodesics on Ruemannian surfaces of some genus which should be determined from theory of billiards.And then Gutzviller's formula can be used at once.

  • Rajesh B Patil asked a question in Turnitin:
    How repeating turnitin plagiarism check works?

    I am about to submit my thesis to my university. University do a plagiarism check with turnitin. I am planning to have this plagiarism check in turnitin at another organization. I heard that turnitin stores the submission in its database and in case even the similarity is well below 15% with my own submission my university through their own login may get 100% similarity with my earlier submission. This is what troubling me. I do have only two chances with my univesity and if returned for more than 15% similarity could take away one year. Please guide me in this matter.

  • Vikas Kumar asked a question in Model Evaluation:
    Anyone knows about in vivo methods for evaluating thyroid?

    We are interested in animal models to evaluate thyroid abnormalities in rodents. 

  • Arindam Basu added an answer in Coronary Artery Bypass Surgery:
    How do I calculate SYNTAX II score?

    As we know SYNTAX II score was published and calculated to evaluate peri-OP risk evaluation before CABG,however, even the original article showed scale like calculation method,however, I still failed to calculated the risk points to predicate risk? Who can tell me more delicately about the formula to calculate SYNTAX II score?

    Arindam Basu · Nilratan Sircar Medical College

    Nowadays, you can even download a syntax score calculator on your smartphone or android...

  • Graeme Smith 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.

    Graeme Smith ·

    Errki, I can't comment on your mathematics, if only because I don't fully understand it, but I can note that your assumption that every neuron is bounded by every other neuron, or that each neuron is surrounded by a sea of every other neuron, misses the well known fact that there are fewer connections than there are neurons to connect to for every neuron. This implies indirection in your connections which in  turn implies the need for a connectome.

  • Umut Cagin Ari added an answer in Spermatogenesis:
    What is the reason of testicular descending in scrotal species (such as cows...);Why do abdominal testes remain internal?

    What is evolution phenomenones during life?

    as you know, every species has a normal fertlization, then I think the types of evof testes position is not an evolution advantages but it might  a physiological advantage. For example the roosbut ters have not spermaticcord (to regulate of testes temperatue) but  their feature is that they have spermatogenesis in their bodies temperatue

    Umut Cagin Ari · Kafkas University

    Dear Mohammed,

    As you know testes must be in scrotum in  all mammalian species. Testes origins from meso-nephrone in embryonic phase and it must be descended in scrotum before birth.   It is needed for thermoregulation otherwise spermatogenesis is detrimentally affected. It is well known phenomenon in reproductive physiology. (I do not talk about thermoregulation of testes)

    In birds, testes must be in abdomen because of aerodynamic issue in evolution. And the thermoregulation is arranged by air sacs in male birds. It is well known.The testes in birds is near the air sac in abdomen so it is not need scrotal cooling.

    My best wishes,


  • Chenyin Wang added an answer in In Vitro Assays:
    Can anyone provide information about making a in vitro biological system without using cell culture work?

    UDPG Dehydogenase enzyme converts UDPG to UDPGA. I want to make a real biological system and mimic all the conditions that a biological system would provide to this reaction to happen. I would apriciate if some one can give me informations about buffer conditions and incubation conditions that would mimic a biological system in a test tube. Thank you 

    Chenyin Wang · University of Macau

    Yes, maybe C. elegans is a good choice to mimic the biologic system in human.

  • Yehia Mahmoud asked a question in Candida Albicans:
    Please, can anyone know what is the name of Enzyme involve in Alcoholic sugar biosynthesis in Candida albicans?

    Candida albicans groups

  • Danilo Russo added an answer in Forest:
    Has anyone information or articles about the destruction of the forests of the world over the past decade ?

    We are investigating the destruction of the forest
    and factors contributing to the degradation of Hyrcanian forests in Iran.

    Danilo Russo · University of Naples Federico II

    The data are not available for all countries and surely there are country-specific reports available for many regions. As far as I know, the following is one of the best existing global databases (it is interactive which means you can explore it by country, download data etc.)


    I hope this helps, all best


  • El Sayed Mahmoud added an answer in Artificial Neural Networks:
    are there any examples on Normalizing the Inputs for Neural Network learning?

    Reading the paper Efficient BackProp by Lecun and company, I need an example on Normalizing the Inputs and Choosing the Target values if anyone knows any?

    More concretely, I am interested in the implementation of said techniques.

    El Sayed Mahmoud · Sheridan College (Oakville)

    It is better to avoid 0 and 1. Normalize all input vectors in [0.1, 0.9] interval.

  • Peter M Muriana added an answer in Bacteriocins:
    What is the protocol to mutate bacteriocins?

    i am doing phd on bacteriocins so i want a protocol to mutate the isolated bacteriocins from lactic acid bacteria

    Peter M Muriana · Oklahoma State University - Stillwater

    You have not given sufficient information to help determine what you want to do?  Are you trying to 'mutate' in regards to eliminating activity? Are you trying to increase activity? Bacteriocins, and the genes that encode them, are so small that you can easily do targeted mutagenesis by PCR rather than site-directed mutagenesis (you probably can even synthesize genes with the specific changes, considering the low cost of DNA synthesis currently). If you are trying mutagenesis to affect activity, and if you have the amino acid sequence of your 'bacteriocin of interest', many bacteriocins (short peptides) have amphipathic helical structure with both hydrophilic and hydrophobic amino acids; these may affect the positioning of the bacteriocin molecule in a barrel-stave membrane insertion mode of action. If you run a peptide motif structure software program to give a suggested helical structure of your peptide bacteriocin, you may select certain amino acids that have more (aliphatic) or less (charged) hydrophobic tendencies and perform site-directed mutagenesis with a targeted approach, depending on where they occur on the helical structure. One way might also be to do some amino acid sequence alignments of different bacteriocins and see what different amino acids are positioned in those bacteriocins that might have homology to your particular bacteriocin.

  • Chenyin Wang added an answer in Collaboration:
    Is there anyone who study neurodegenerative disease by using C. elegans as the model?

    My project is mainly focus on AD and I choose C. elegans instead of SH-SY5Y cell line or mouse because I think it is cheap compare with mouse, and it is a whole animal model compare with cell. I want to find somebody who also works with C. elegans. We can share some experience and help each other.

    Chenyin Wang · University of Macau

    Thank you for your suggestion. It helps.

  • Yehia Mahmoud added an answer in Pulp and Paper:
    Need to know some microbes (apart from human pathogen) involved in rotting of pulp and paper?

    name of the species responsible for rotting of pulp and paper specially bacteria and fungi.

    Yehia Mahmoud · Now:AlBaha University, Albaha, Saudi Arabia- permanent: Tanta University

    Species of Geneus Conidiobolus , and order mucorales and entomophthorales

  • Netra Pal Singh added an answer in Plagiarism:
    What percentage (maximum) of plagiarism is generally allowed in a review paper?

    I want know about what percentage of plagiarism is allowed to make a review paper acceptable in journals.

    Netra Pal Singh · Management Development Institute Gurgaon

    which part of research article you are evaluating for plagiarism. If it is review of literature then you may like to tolerate as per the percentage of common references. Similar should be the case for research methodology. However, if you are evaluating results, conclusion than percentage should be as low as zero percentage. It mean it should very for different parts of research paper.

  • Cyril Mechkov asked a question in Electronics and Communication Engineering:
    How do we investigate semiconductor devices in the educational lab?

    This autumn, I have to conduct with students of a new IT specialty a series of lab exercises related to study of basic semiconductor devices: ordinary, zener, light, tunnel and other diodes, bipolar and FET transistors, diode and transistor circuits... So, I temporarily leave the “kingdom” of my favorite analog circuitry where I deal with circuit systems and move to the lower level where I will reveal and show the secrets of circuit components. The problem that stands before me is how to do this in the best way...

    I have unpleasant memories of the way they conducted laboratory exercises in this discipline in the 80's, when I studied in the same university. I remember that I had to perform a series of programmed actions on ready-made laboratory setups enclosed in boxes so their internal structure remained hidden for me...

    That is why, I decided to conduct more interesting laboratory exercises with my students where they can conduct free experiments on flexible prototyping boards by all sorts of components instead of hard prepared experiments on closed laboratory setups. Thus I hope to motivate them by waking their curiosity and creativity.

    My idea is first to pose the problem on the whiteboard, then to find the possible solutions and finally, to implement experiments in various ways. Students can investigate IV curves of diodes and transistors at four levels:

    • manually - driving the circuit by a potentiometer and measuring the electrical quantities by digital multimeters or a digital oscilloscope in XY mode (shown in the first attached picture below)
    • semiautomatically - driving the circuit by a functional generator or simply by a 50 Hz transformer, and measuring the quantities by an analog oscilloscope in XY mode (the second picture)
    • automatically - by a data acquisition board equipped by an appropriate periphery

    It would be interesting for me to know your opinion about such an educational experiment. Whether it would be feasible or would be extremely difficult for students and, as a consequence, for me?

  • Kenton P Arkill added an answer in Fluorescence Microscopy:
    Can anyone recomend a ccd camera for an olympus bx-41 fluorescent microscope?

    For routine fluorescence techniques, including some quantification experiments

    Kenton P Arkill · Unversity of Nottingham & Universidad del País Vasco / Euskal Herriko Unibertsitatea

    The Qimaging/Photometric's have a good range to guide price.


    hamamatsu are the microsoft/apple equivalent.

    Just watch for software and if it can be run from software/computers you already have by the microscope. 

  • Jyothy S added an answer in SPSS:
    Can anybody help me with cluster analysing the antibiotic profiles in SPSS?

    Here is the link of an article, with the same.

    Jyothy S · Mahatma Gandhi University

    Thank You Felix! I have already tried the hierarchical cluster analysis in SPSS; but the resulted  dendrogram was too much confusing! I think I have made some mistake during the input of data. :-(

  • Sofia D. Wechsler added an answer in Theoretical Physics:
    Can Quantum 'Mechanical' Description of Physical Reality be considered Completed?

    Simplicity is the key to the interpretation of physics. Nothing more simple in the analysis than supposing the existence of some parameter "hidden," invisible and not measurable which is an integral part of a pair of photons and that tells at the time of their creation: "you are oriented east" or "you are oriented to the west. "This analysis requires us to introduce "hidden variables", a process which in physics is debatable, but allows in a very elegant way to explain everything in realistic terms. The pair of photons has its own objective reality that can describe them completely. Part of this reality is unknowable but never mind, the problem is only human, nature is safe.

    We have two options: 1) quantum mechanics is inherently probabilistic; 2) quantum mechanics is not inherently probabilistic, but deterministic. The first position is that of the so-called "Copenhagen interpretation", still very accredited by physicists, while the second was that of Einstein-Podolsky-Rosen (EPR) and of the "hidden variables". Subsequently, Bell showed that the hidden variables can not be there. John Bell in 1964 pointed the way for an experimental verification of the existence of hidden variables, but subsequent experiments, especially the French group of Alain Aspect, have shown the full validity of quantum mechanics.

    Then, the second theoretical position is no longer sustainable. Instead it is if we consider the fact that the "ontological materiality" turns out to be greater than the "physical". There are no additional variables that may enter into the physic calculation, but there are physical materials that physics fails to consider which have an impact on theorizing. These factors determine the overall behavior of matter which, therefore, appears inherently probabilistic. It can be said that Einstein was right: the hidden variables exist, only that they lurk outside of physics, in ontology.

    Many physicists (Einstein leading) have always refused that indetermination be an inherent feature of physical reality. Consequently, they preferred to assume that the description provided by quantum mechanics was simply incomplete. Their reasoning, in practice, consists in saying: even at the microscopic level physical reality continues to be deterministic, only that we can not know the exact values of the state variables and so we are forced to an indeterministic description. To explain this failure many proponents of determinism (starting from Einstein himself) introduced the so-called "hidden variables". At the microscopic level, there would be some factor that is not yet known which would prevent us from a deterministic description. The moment we knew, we could provide a description of these factors completely deterministic

    For many years the debate between the advocates of the hidden variables and the promoters of intrinsic indeterminism remained on a purely metaphysical level. In 1964, however, the physicist J.S. Bell derived a famous inequality (Bell's theorem) that allowed to transfer experimentally what until then had been a metaphysical discussion. Such inequality, in practice, led us to expect different experimental results depending on whether had been true the hypothesis of hidden variables (at least limited to the so-called "local theories") or not.

    Now, the Heisenberg principle would not only establish our inability to learn at the same time the values ​​of the position and momentum of a particle. These values are established, before a measurement be made, they are absolutely and inherently indeterminate.

    Einstein's objections to quantum mechanics made sense because he was perfectly aware that quantum mechanics is incompatible with determinism. However, his views obstinately deterministic and his attempts to defend them (hidden variables) have not stood the test of facts.

    The microscopic reality is inherently indeterminate. However, what is surprising is that the macroscopic reality is instead largely deterministic. To explain this apparent contradiction is a fascinating challenge in theoretical physics. An interesting attempt at a solution appears that provided by three Italian physicists G. Ghirardi, A. Rimini and. T. Weber (in Physical Review D 34, 470, 1986).

    So, in this context it became obvious that the description of the states of a physical system offered by quantum mechanics was incomplete and that such an incompleteness was responsible for the indeterministic character of the theory. In other words, it has been assumed that quantum mechanics is indeterministic only because our level of knowledge does not put us in a position to "see" some additional variable, able to "complete" the description of the physical system provided by quantum mechanics. According to this conjecture, if we were able to identify these new variables, currently "hidden", we would recuperate a level of description deeper than the quantum level and at that level determinism could be recovered. "

    In fact, the enigma of the "hidden variables" was not solved by a logical-deductive approach, as Popper might have wished, or was it only partially.

    As already said, “in 1964 the issue was a crucial turning point: J. Bell showed that for a large family of theories and hidden variables, the so-called local theories, it is impossible to reproduce with media operations on hidden variables all the predictions of quantum mechanics. "" the result of Bell had the great merit of showing on the experimental ground the theme of possible deterministic completions of quantum mechanics, and a great interest aroused for the realization of experiments sensitive to discrepancies between the predictions of quantum mechanics and that of the local theories of hidden variables . "(Enrico Beltrametti)

    In 1981, Alain Aspect was able to realize the first of a series of experiments of high quality. In practice, the experiment showed that Einstein had been wrong in suggesting the idea of hidden variables.

    As for Popper, we could say that he lost a game: the one with LQ,

    Criticism of Popper was wrong from a logical point of view, but in many ways it had some basis. Popper did not want to admit a weakness of logic explicit in theory LQ. For Popper's logic was to remain an ‘a priori’ science, having as main feature the absolute independence from any content. Therefore, he refused to consider the possibility of choosing logics different from the logic, most suitable than this to the empirical character of particular situations.

    Already in the Logic of Scientific Discovery, which was finished in 1934, then prior to the writing of Birkhoff and von Neumann, Popper anticipated: "... replacing the word" true with "the word" likely "and the word" false  with "the word" unlikely ", nothing is gained.

    However Popper earned another no less important point. The revolutionary discovery of Bell and Aspect was not from a pure inductivism, but from experiments carried out in the light of a theory already formulated ‘a priori’, then from a hypothesis to be subjected to strict scrutiny, identifying the elements and data that could refute it. At least on this ground, Popper took an important rematch.

    At the time of the article in Einstein's death, the controversy was still strong and "philosophical" issues had a great weight, so much so that an American physicist was the victim of McCarthyism and lost his job for supporting a deterministic model with hidden variables. Today we tend to minimize the importance of our imperfect knowledge on the subject; theories are used as they are reaping the fruits without worrying about a coherent understanding of the underlying laws. Most physicists do not interpret more the principle of indeterminism  in a metaphysical way. It is considered as a simple impossibility of knowing at the same time position and momentum of the particles in a system still felt completely deterministic. After all, beyond the supposed wave-particle duality, also in the macroscopic world there is a kind of uncertainty: for example, I can not measure my speed with accuracy higher than my reaction time to press the button on the timer.

    Sofia D. Wechsler · Technion - Israel Institute of Technology

    Hi, Charles,

    and again thanks for the Stone's theorem.

    Now, you see, what people try to find is WHAT IS, not what IS NOT. Do you remember what J. Bell said" "The entanglements cry out for explanation, not for description"?

    More mathematics won't help. QM is not complete not because it is not deterministic, we are ready to eat this bitter pill. But QM is not able to answer to a simple problem. Please see it:

    Assume a pair of entangled particles, 1 and 2, and a correlation implied by the wave-function. Now, consider also a frame of coordinates by which the particle 1 is measured first. What does the nature? Produces a result. Is this result influenced by the data (type of measurement and result) of the LATER measurement of the particle 2?

    Is doesn't seem reasonable that the future influences the present. So, let's answer negatively. But, by symmetry, in a frame by which particle 2 is measured first, we have also to admit that future does not influence the present (according to the time axis of the new frame).

    Then how can the nature realize the correlation?

    So, what's going here? Could it be that there exists a preferred frame? Or, the future indeed influences the present?

    Bottom line, with such unsolved problems, how can QM be a complete theory?

  • Jiaqing Zhou asked a question in Turbulent Flow:
    In which media is the turbulent flow more prone to occur? Porous media or fractures?

    Hello everyone! I want to know in which media is the turbulent flow more prone to occur? Is that porous media or fractures? If so, is there any reference supporting the judgement? I'm looking forward your answers, thank you so much!

  • Daniela Vandepeer added an answer in Cross-Cultural Comparison:
    What are cross-cultural differences in terms of assessment and evaluation practices in educational settings?

    cultural differences with respect to evaluation and testing.

    Daniela Vandepeer · University of Cambridge

     Thank you for all comments in response to my initial response to Rahimi's question.

    OECD, PISA and TALIS studies highlight findings relating to assessment and evaluation practices in educational settings. 

    For instance, below is an extract from the 2012 report on Netherlands which confirms how very complex such practices are and why:

    ''Implementation, appreciation and use of evaluation and assessment
    Implementation of evaluation and assessment procedures in the Netherlands has sometimes
    hampered because of a lack of cooperation from schools in data collection procedures. This lack
    of cooperation first occurred in the 1970s when program evaluations were implemented and is
    also indicated by reoccurring problems for the Netherlands in obtaining sufficient response rates
    in international studies. For this reason, the Netherlands was excluded from the international
    reporting on PISA 2000 and the first wave of the TALIS study (about the functioning of teachers).
    School autonomy and a general weariness of administrative burden might explain this
    phenomenon. Still, a large number of (autonomous) schools (85%) have purchased important
    student assessment instruments like the Cito school leavers test and pupil monitoring systems.
    With respect to the implementation of school self evaluation a mixed picture emerges. It is the
    impression that schools generally own school self evaluation instruments, including administrative
    systems. Yet, the proportion of schools which, according to the Inspectorate, have a wellfunctioning
    internal system of quality assurance is not increasing at a level that was expected.
    Systematic information on schools‟ appreciation of evaluation procedures is only available with
    respect to school inspection. Generally schools are satisfied with the work of the Inspectorate. An
    internal review by the Inspectorate pointed out that the recent risk based inspection is successfully
    being implemented and has shown results in the sense of a diminishing number of very weak
    The notion of evaluation and assessment stimulating the improvement of teaching and learning
    works differently for evaluation procedures at system, school, teacher and student level. In a
    general sense all types of evaluation and assessment, both summative and formative, are
    ultimately meant to improve educational achievement through improved teaching and learning.
    Feedback loops and improvement mechanisms will differ, however, both in length and in the role
    of different actors in using evaluative information for improvement purposes.
    With respect to the use of system level evaluations there is only fragmented and anecdotal
    evidence available. The availability of periodic synthetic publications such as the annual report of
    the Inspectorate and the publications on Trends and Key Figures must be seen as an important
    condition for facilitating the use of system level evaluations. Since the reporting of the
    Parliamentary Committee “Dijsselbloem” in 2008, public interest in the position of the
    Netherlands on international assessment tests, such as PISA, seems to have grown, and has been
    the object of some debate in the press.
    Research studies point out that the extent to which schools implement self evaluation procedures
    and use self-evaluation results for school improvement is often superficial and problematic.
    Similarly, recent and ongoing studies into schools using student achievement data to improve
    teaching and learning (which is motivated by Departmental action plans) point out that teachers
    often lack required skills and expertise to make optimum use of these data. The good news is that
    these practices can be considered as touching the core of what evaluation and assessment can do
    for improving teaching and learning, and that current improvement and evaluation policies in the
    Netherlands are addressing this very core.''

  • Umut Cagin Ari added an answer in Egg Yolk:
    Are there any ways to filter egg yolk for semen extender?

    i have some problem with egg yolk in my extender and i think its need to filter before i add it in my extender

    Umut Cagin Ari · Kafkas University

    Dear Farhad,

    You did not exactly mention of problem about egg yolk usage in extender. As you know, it is important to use only egg yolk without albumin or membrane rich parts. So you have to sure that you can purely separate egg yolk before addition to extender. For this aim, we do not need any filtration method. 

    An other problem about egg yolk (as mentioned by Ahmed Ali) is emulsification of egg yolk in extender. I agree Ahmed Ali you can well shake egg yolk. Also I want to give additional knowledge about this issue. 

    Another method is that you can use ultrasonic washers for this aim if you have in your lab or magnetic shakers. Also we determined that we obtain good results if we add egg-yolk to extender one night before usage. We think it is about emulsification of egg yolk in extender. 

    I hope my information will be functional. If you give information about problem with egg yolk I try to help more specific.

    My best wishes,

    Good luck...