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  • Andrew Odell added an answer in Cosmology:
    How do astrophysicists, or others, record/analyse/display different resolutions on images of stars/galaxies if they are differing light-years distant?

    If I'm correct that images of distant stars and galaxies can show multiple celestial objects at massively differing distances away and therefore some points of light are effectively representing images from differing moments in the past.

    If those different points of light are actually derived from differing moments in time, how do observers/recorders represent the difference in time between them visually or analytically?

    Andrew Odell

    Keith, I think astronomy would be like anthropology if you were a million years in the future!  The difference in age between one layer and the next would be only a few centuries, and you would say all layers are contemporary.  You would say, 'people lived here.'

    You ask, "Do astro-physicists have any similar (presumably more sophisticated) methodologies...?"          Yes, we do have - we ignore it.

  • Salil Batra asked a question in Computer Aided Diagnosis:
    How neuropsychological tests are helpful in computer aided diagnosis of alzhemier??

    Current research in the computer aided diagnosis of neurodegenerative diseases

  • Razieh Haghighati added an answer in Missing Data:
    How do you differ "missing data with ignorable mechanism" and "missing data with non-ignorable mechanism"?

    Little and Rubin (2002) introduced three major missing data mechanisms. If the cause of missingness is independent of data, missingness is called missing completely at random (MCAR).  On the other hand, in missing at random (MAR) mechanism, missingness depends on data which is observed yet independent of the unobserved data. Finally, third mechanism termed missing not at random (MNAR) because the pattern of missing data is non-random and depends on the missing variable.

    According to the literature, you cannot ignore missing data which is "Missing not at random" (MNAR). My question is: given a dataset, how do you identify the missingness mechanism?

    Razieh Haghighati

    I monitor industrial processes. I am interested to find pattern of data. To do so I monitor how recorded measurements of a single quality characteristic (such as weight) change in several products while passing a specific step in production line. I need around 20 data samples to decide about the pattern. However, sometimes a part of data is missing. If the data is "missing not at random", we need to stop the process

  • Sehrish Naz added an answer in Virtual Screening:
    How do I validate pharmacophore in absence of reported inhibitor?

    I want to design protein-protein interaction modulator via virtual screening of large databases by utilizing structure-based pharmacophore of protein-protein complex. Can someone guide me how to validate that pharmacophore If there is no inhibitor reported against my target protein.

    Sehrish Naz

    Dear Pankaj,

    Thank you now I got your point. I have already decided to follow the strategy you suggested me. I just want to assure myself. Thank you for helping me.

  • Niklas Thilo added an answer in Antibodies:
    What are the causes of Transient Hypogammaglobulinemia in an adult?

    I recently came across a 60 year old lady who had been treated for HCV infection. She was documented during evaluation to have low serum immunoglobulins and the Immunoglobulin profile showed low IgG (312 mg/dl, normal being 700-1600), low IgM (30.5 mg/dl, range 40-230) and IgA (< 50, range 70-400). She did not have chronic diarrhoea, nephrotic syndrome or cirrhosis. Her LFT and RFT were normal. She gave no history of having consumed steroids or being given rituximab. Her CD4 and CD8 counts were normal.

    A repeat test , 2 weeks later, showed normalisation of gammaglobulins level. Is it purely lab error or could there be some explanation for this phenomenon? 

  • Muhammad Khattab asked a question in Absorption:
    What is the difference between Absorption and excitation Spectra?

    I am wondering about the difference between Ab and Exc spectra? what does it mean if they are 1) identical and 2) non-identical? Also, i want to ask what is the impact and importance of changing emission wavelength while recording the excitation wavelength.

    Thanks in advance,  

  • Ramasamy Raj Kumar added an answer in Schiff Bases:
    I am modifying a schiff base complex in order to enhance its fluorescence property. Do you know any functional groups that could be added into it?

    The attached file is the structure of complex.

    Ramasamy Raj Kumar

    Depending upon the ligands which possess luminescence property moities like carbazole, 9-anthracene etc..

  • Godwin Polendey added an answer in Beauty:
    I want to do a review on beauty. Could my colleagues express their opinion on who is considered beautiful in their part of the world?

    I want to do a review on beauty. Therefore I would like to ask my colleagues from different countries of the world if they would like to express their view on who is considered a beautiful woman in their part of the world.

    Godwin Polendey

    I think people have different taste and preference therefore there is no true definition of beauty. But I think you would find it interesting to know that in some Asian cultures, having a pale white skin is considered beautiful. In my country, the Philippines, having a pale skin is associated with being on the high level in society. 

  • Brian McDonagh added an answer in Gold Nanorods:
    Has anyone experienced problems with reducing disulfide bonds using TCEP/DTT?

    My molecule is in a dimer form, however, I would like to get it in a monomer form. Both TCEP and DTT in 50 eq. reducing agent to dimer I do not observe any reduced compound, I used fresh TCEP/DTT. 

    I do have a strong preference for no sulfur containing reducing agents like TCEP, as I would like to react my monomer with gold nanorods, which binds to all thiols. 

    Brian McDonagh

    It might be worth adding an alkylating agent such as IAM or NEM after you have reduced disulphides with TCEP, it may help stabilise the protein.

  • David Soler-Delgado added an answer in Graphene Electronics:
    Should I connect graphene to electrode above or below flake?

    Hi -

    I have seen many papers making graphene devices. Some researchers put a flake on the substrate and then pattern electrodes above the flake.  Other research is done by first making an electrode, then landing the graphene on top of the electrodes.

    What determines their choice, other than experimental challenges associated with each of these methods? Is there a difference in the performance of the metal-graphene contact?

    David Soler-Delgado

    The reason for doing bottom contact and top contact might not be directly related with the performance of the graphene-metal contact, but with the substrate effects produced on graphene. On suspended graphene (landing graphene on the top of electrodes) the electron mobilities reported are way higher compared to graphene deposited directly on SiO2. Some other interesting physics appears with different substrates, so I believe it depends on what is the purpose of your research. Be aware that suspended structures are not that easy to make.

  • Nagaraj Adiga added an answer in Flow:
    How do I estimate spectral tilt from the glottal flow waveform?

    Given a Glottal Flow Waveform how does one obtain the spectral tilt in the frequency domain.

    Nagaraj Adiga

    if you take windowed signal which consist of multiple glottal pulses, in freq domain  you can find the peaks due to fundamental and its harmonic components, which can be picked or you can use this ref also http://link.springer.com/article/10.1007%2Fs10772-011-9100-x

  • Paul Stephens added an answer in Educational Assessment:
    Some students do not attend lectures and depend on voice recordings. Is this an acceptable method for successful learning?
    How can I tell if my students are learning if they are not attending?
    Paul Stephens

    This has proven to be a stimulating question, Abdullah. I understand the argument that a video recording is hardly different from a non-interactive lecture. That said, I think it unwise, except in exceptional circumstances, to give non-interactive lectures. When I lecture, I seek to convey content not only by referring to my my lecture notes, but by also inviting students to comment on my arguments in real time situ. Yes, there can be a balance. Too much interaction can easily became "chit chat". Notwithstanding, I stand by my argument that a spoken living word trumps a video every time. Why attend music concerts if the orchestra or band can simply sell videos of the performance? 

    Best wishes, Paul

  • Huei-Yu Chou added an answer in Methanol Oxidation:
    How do I precisely qualify the synergistic effect of Pd-Pt core shell catalyst for breaking the C-H bond such as in methanol oxidation?

    I sequentially synthesize Pd nanoparticles less than 10 nm  on carbon paper and then Pt thin film  or layers on Pd particles  by electrodeposition. How to related mass activity or specific activity of Pd-Pt core shell with pure Pt performance in methanol oxidation or just take into account the potential peak shift in cyclic Voltammetry, which involve the d band shift of Pt with Pd? 

    Huei-Yu Chou

    Thanks, Bruno Previdello. It is supposed that chronoamperometry (CA) is typically suitable for decay study of these catalysts in electrochemical reaction to see if the catalyst is durable or not. I believe that a long term decay measurement is necessary, at last.

    A serious point of core shell catalyst still remains a problem that how long it could be sustained. Personally, that depends on thickness of shell on the core of catalyst and what overpotential we applied in electrochemical reactions . Normalized current density by loading Pt mass is a popular criterion to compare essential electrochemical characters of catalyst in different research situation. There is another point of electrochemical surface area (ECSA) for Pd and Pt. How to separate the ECSA between Pd and Pt? As you mention by CO stripping in CV?

  • Michael Päch added an answer in Chemical Synthesis:
    What is the best way to synthesize N-Chlorodiisopropylamine?

    is this possible?

    Diisopropylamine, 10.1 g (0.10 mole) , was dissolved in 500 ml of dry ether at 25°c. N-Chlorosuccinimide, 13.5 g (0.11 mole) , was slowly added and the mixture stirred for one hour in the dark. The mixture was cooled to 10°c and the succinimide removed by suction filtration. The ether solution was washed with 1 0 % hydrochloric acid and dried over anhydrous sodium sulfate. Removal of the ether under vacuum left crude N-chlorodiisopropylamine, 12.5 g (0.09 moles), which was used without further purification.

    I have been done this method , but I did not get a good result.

    Michael Päch

    (COCl)2 gives the corresponding amide, not the N-chloroamine,

    NaOCl, chloroamine T, tBuOCl etc. are reagents to N-chlorinate.

  • Muhammad Khattab added an answer in UV-Visible Spectroscopy:
    Can anyone suggest how to have my cuvette completely sealed to prevent solvent evaporation during temperature dependence fluorescence measurements?

    I have already a polyethylene lid which is not efficient. I tried to use parafilm but the solvent still evaporates. I tried to put Aluminum foil then the lid on to make it a quick fit, but the solvent still evaporates.

    Muhammad Khattab

    Thanks, All!

  • Cesare Gargioli added an answer in Muscle Biopsy:
    Does anyone have a protocol for the isolation of muscle derived stem cells from primary human muscle biopsies?

    I am trying to culture the MDSCs from human skeletal muscle and the protocol I'm following is the one published by Eberli et al. in 2009 (http://www.sciencedirect.com/science/article/pii/S1046202308002016).

    I'm using the same collagenase and dispase digestion, and ending up with a mass of hypercontracted fibres and mostly fibroblasts. Does anyone have any advice with respect to the handling and digestion of the muscle during the isolation so as to ensure myofibre viability? I'd be very grateful for your input!

    Cesare Gargioli

    Plating the cells at very low confluence after serially filtering avoid fibrobalst contamination, nevertheless the only way to discard fibroblast is cell sorting either fluorescence or magnetic.

    Regarding muscle fibres, I do not really understand what do you mean with "live muscles fibres out of wich..." after micing and enzymatic digestion you will never collect any fibre, just a very small pieces of this. There are othere protocol using different isolation protocol the forecast single fibre plating to isolate coming out satellite cells.

      Best luck


  • Kasurika Dissanayake asked a question in Building Materials:
    Can anyone suggest a free database for building materials, compatible with openLCA?

    I need to conduct a comprehensive Life Cycle Analysis on a precast building system in Sri Lanka. I hope it is more accurate and easier to use a software for this (like openLCA). But the main problem is there are no freely available databases for Sri Lanka.

    Is there any other reliable and easy to use software I can use, within a limited budget?

  • Massih Afghah added an answer in Geology:
    How can I evaluate the pore structure characteristics of core samples at different locations?

    Recently,I have got a core sample with the size of 2cm×4cm. We have used the core sample in a high pressure high temperature test to inverstigate the effect of tectonic deformation on shales. Thus, we want to know the pore structures characteristics at different locations of this sample. The pore paramaters include pore size distribution, surface area and pore volume, etc. Maybe, we guess, several testing methods should be used.

    Hope your good suggestions! Thanks! 

    Massih Afghah

    Dear Hongling

    according to your question you should necessary to note that the dimension of interconnected pores plays a major role in determining permeability. Most methods of estimating permeability are indirect methods. A viable direct method requires both adequate theoretical underpinnings relating pore throat dimension to permeability and experimental determination of the critical pore dimension parameters. Many authors have made use of the capillary pressure curve, obtained experimentally by injecting mercury into a dried sample. As mercury pressure is increased, more mercury is forced into progressively smaller pores in the rock, and the resident pore fluid (air) is expelled. A length r, usually referred to as the pore throat radius, is related to the injection pressure by the Washburn equation.

    There is a direct method for core porosity which is direct measurements of porosity data on core samples in a laboratory typically require measurements of bulk and pore volumes of the core samples. For irregular-shaped core samples, the bulk volume is determined by gravimetric or volumetric methods. In gravimetric methods, the apparent loss in weight of the sample when immersed completely in a liquid of known density is measured. Volumetric methods measure the volume of liquid displaced by the rock sample when completely immersed in the liquid. These methods use specially designed equipment so that the liquid is not absorbed by the rock sample. For regular-shaped samples, the bulk volume is calculated from physical measurement of the dimensions of the core sample. For instance, if the core plug is cylindrical in shape, the bulk volume is calculated as:

    Equation 1.6

    V= 3.14* rrl 

    In Eq. (1.6), VB = bulk volume; r = radius of the core plug; and l = length of the core plug.

    However you can refer to link below:




  • Anurag Pandey added an answer in Gas Turbines:
    How can I design or select an air filter for gas turbine?

    Hi, i have been doing the air filter inlet system design for gas turbine power plant. i couldnt get much info about air filter thickness and air flow rate ,how its affect the effciency ??i mean pressure drop..how to reduce the pressure drop?..how many air filters we have to use for 250MW gas turbine? any info.

    Anurag Pandey

    Please use these links for reference.

    Best of Luck.

    + 3 more attachments

  • Manohar Sehgal added an answer in Solar Energy:
    How can copper oxide be applied in solar cell technology?

    I've read in some statements here that one of the applications of copper oxide is that it can be used for solar energy transformation, but how exactly is a nano particle used in such way? 

    Manohar Sehgal

     My young friend, you   find some  work already reported  on the application of copper oxides in solar cell technology.

    Pls find attached  references for 4 papers along with their  respective abstracts.Hope they prove helpful to any beginner.

  • Adil H.H. Bashir added an answer in photodermatology:
    What could that photodermatosis or photoaggravated condition be?

    A 9-year-old healthy girl with a very fair skin lives on the coast. Since 3 years asymptomatic quite large bright brown maculas appear during Summer on her face and arms. They disappear in October.

    + 1 more attachment

    Adil H.H. Bashir

    Ephelides or Freckling  is most frequent in individuals with red or blonde hair and blue eyes, particularly in those of Celtic extraction. Red-haired individuals with fair skin (and
    freckles) have a significantly higher incidence of the gene encoding melanocortin receptors. They increase in number, size and depth of pigmentation during the summer months and are smaller, lighter and fewer in number in the winter. Freckles are a feature of a number of inherited and acquired disorders include xeroderma pigmentosum, neurofibromatosis, Moynahan’s syndrome and progeria.

  • Antonio Delgado added an answer in Multiphase Flow:
    Why "rho" is considered as constant at continuity equation for multiphase flows (water-air)?

    At numerical simulation of multiphase flows (water-air) almost all authors use continuity equation as "\partial ui / \partial xi = 0". Why "rho" is considered as constant? I understand that is an incompressible flow, but "rho" varies at space and time.

    Antonio Delgado

    Dear Leonardo,

    This is a very good question. And I have to state that different authors in literature would provide to you different answers. In addition, several authors do not accept a constant density even in the case of pure liquids. This is due to the fact, that the (differential) continuity equation is a (continuum) model that is based on certain assumptions. In the case of pure liquids it is in general postulated that liquids can be treated as incompressible. In fact, to compressed liquids substantially, very high pressure or kinetic energy are required due to the molecular forces acting within in the liquid. However, if extremely high pressure gradients are available, second order effects can occur that make constant density in the differential continuity equation questionable.

    For multiphase flows (air-water) the most convincing "model explanation" for a constant density in the continuity equation is that not only the liquid phase but also the gaseous phase behaves incompressible if the kinetics of the flow field does not exceed certain limits. The most popular statement is that the velocity of the gas should be sufficiently small in comparison to the velocity of sound, i.e. that the Mach number Ma should be sufficient small.

    Under this condition, the density of a water-air-flow can be considered not to depend on the flow field. Instead it can be considered purely as an intensive thermodynamic parameter. As other thermodynamic parameters the density depends chiefly on the temperature and the pressure. Thus, the density can change in space if a temperature or a pressure field is present. However, for small kinetic energy of the flow (small value of Ma) the density depends in a first estimation only on the temperature. Thus,  for steady flows "\partial ui / \partial xi = 0" would represent a reasonable model even for water-gas-flow if, additionally, the flow field is nearly isotherm.

    With compliments


  • Paresh Poriya added an answer in Zoology:
    Can any body give name to this zooanthid?

    from Karachi intertidal

    Paresh Poriya

    I am not exactly clear but both species may be Zoanthus sancibaricus.

  • Jan Gunneweg added an answer in Archaeological Excavation:
    Where are the human remains of the Minoans from the destroyed city of Akrotiri in Crete?

    The Thera  eruption destroyed most of the island today known as Santorini.

    Akrotiri, located on the eastern tip of the island, was destroyed as the archaeological excavations show at present..

    Nevertheless, no human remains have been found wit the exception of a few skeletons.

    The primary question is: What happened to the Akrotiri population of which no remains have been found?

    Jan Gunneweg

    Dear Ioannis, something went wrong with your message; please, fill in the rest. Thanks. Jan

  • Tushar Ashok Kshirsagar asked a question in Rietveld Refinement:
    How to do Rietveld refinement of sodalite?

    Rietveld refinement

  • Mohammad Khorsand-ghayeni added an answer in Electrospinning:
    The overlap and fusion of fibers can cause changes in the mechanical strength of electrospun scaffolds?

    please see the pictures.

    I want to know about overlap and fusion of fibers in the C part in attached picture. it can cause changes in the mechanical strength of electrospun scaffolds? how?

    increase or decrease? 

    can you introduce an article to me? thanks

    Mohammad Khorsand-ghayeni

    Thanks Zhonggang

    can you introduce an article about "ability of the network fibers to align together under loading" that i can refer it in my manuscript?

  • Nikos Tsimerlis added an answer in Stevia:
    Does anyone knows methods or protocols on how to remove bittering principle from Stevia leaves?

    Stevia is a plant that can be used as a natural sweetner

    Nikos Tsimerlis

    By using Agrostemin, during the growing season. It decreases bittering agents and increases sweetness.Had tests In Kenya and Serbia, next growing season in Bulgaria also. www.agrostemin.com

    The quantity of yield is substantially increased too.

  • Juan-Manuel Lopez-Muñoz added an answer in Sociolinguistics:
    What books can I consult on issues concerning language representation?

    I am working on my thesis on the representation of spoken French in selected Drama Books from the the region of Québec.

    I would like to get more information on Language Representation so I would appreciate it if I could be directed as to which books to consult.

    Juan-Manuel Lopez-Muñoz

    Je vous suggère ces deux références (les deux sont disponibles en ligne):

    BRONCKART, Jean-Paul. « Langage et représentation »s. In: Le langage. Nature, histoire et usage. Auxerre : Sciences humaines Editions, 2001. p. 303-308

     Philippe Malrieu. « Langage et représentations ». in La genèse de la parole: Actes du 16ème Symposium de l'association de psychologie scientifique de langue française, Presse Universitaire de France, pp. 89-130, 1977.