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  • jean claude Dutailly added an answer in Theoretical Physics:
    Is the concept of field the proper way to describe physical processes?

    What is a field? Everywhere around a 'source' of the field, if we put a 'test particle', then a 'force' will be applied to it, coming from the source.
    This definition has a critical drawback:

    • if you calculate, using volume integrals, the total energy of the field , then you will find it infinite. Is this acceptable?

    On the contrary, there exists the interaction from a distance view, where a force is applied to the test particle only when it is being present in the neighborhood of the source. So, we have not any kind of infinite energy here.
    Which approach do you believe that is correct and why? 

    jean claude Dutailly

    Erkki,

    It would be rather long to develop what you ask for. I will try.

    Any Science, such as Physics, is built in several layers. At first we have scientific laws : we have identified physical objects and properties, to which we have assigned some mathematical representation. Then the law can be stated as : there are always some relations between the values of the variables which have been identified. But science is not just a collection of laws, this is a narrative, which is built around these concepts, basic assumptions, first principles and a formalism. It enables us to forecast new laws, which can then be checked afterwards. This is in the elaboration of the theories that the true genius of mankind takes place. Usually a theory cannot be proven directly, only the laws which can be deduced, and theories are revised. So we have relativity or QED, or the standard model. 

    In Physics we use mathematics as the formalism : the logical motor to deduce laws and make computations. The formalism that we use is not neutral. It would have been impossible to invent the theory of Mechanics without differential calculus. So mathematics bring more powerful tools, but we have to be aware that the tools are not the reality. For instance the concept of force field is represented in Maxwell's theory as a map which is defined everywhere, in a 4 dimensional universe. This is consistent with the concept of field, but it is clear that we cannot accept that the field has a value in the future. What happens is that there is, in Relativity, a mediator, the observer. He can imagine and compute a map which is defined at any time, but each observer has access only to a part of this universe, in which he can make measures and observations. And to have a full picture we need to account for this fact, and patch together the view that each observer gets from his own window. This is the job of the Lorentz transformations. So the immediate scientific laws get a meaning only after this reconstruction has been done.

    Similarly we define continuous maps, for instance for the fields. Which means that, if we wanted to know the map we should need an infinite not countable number of measures. Which is impossible, not because of precision, but because there is adiscrepancy between our representation of the phenomenon (a continuous map) and what we can actually observe. As a consequence, to check our laws, we simplify the representation of the phenomenon : we replace the map defined in an infinite dimensional vector space by a map defined by a finite number of parameters, which can then be estimated by the usual statistical methods. There is nothing wrong in this, but we have to be aware that the simplified specification is not the real thing. And of course when you have the simplified version, it is not surprising that you get simple and linear relations.

    As about Hume,...I am not a great fan of the empiricists as you can guess Charles (I stick to my Kant and a bit of Nietzsche) but the statement that you quote can very well stand for the Principle of Relativity : the laws of nature do not depend on the observer, and of course, more : there would be no science if there was not, deeply, some permanence. And there is some contradiction, in these two statements, on one hand the affirmation of the free will (the observer is not submitted to the laws that he observes) and on the other hand there is something which goes on, whatever, we do. The more I think about all this, the more I believe in the true originality of the human mind.

  • Ying Henderson added an answer in Cell Culture Techniques:
    Is there a best way to pick up cells from colony in cell line culture from 6 wells plate ?

    Is there a best way to pick up cells from coony in cell line cuture from 6 wells plate ? I need to isolate some cells from colony /well from 6 plate wells and incubate them, freezing some other.

    Ying Henderson · University of Texas MD Anderson Cancer Center

    I have picked soft agar colonies using the way John described.  That only works for colonies in suspension or in soft agar.  I assuming the colonies Ahmed talked about were the ones attached to tissue culture plates.

  • Ravi Ananth added an answer in Diffraction:
    How do I grow and check whether the crystals I got are diffractable?

    I have got some crystalline stuff as my reaction product how do I check whether these are diffractable crystals or not?

    Ravi Ananth · OnSight Technology USA

    Since the incident beam in this case contained both KAlpha 1 & 2 , each reciprocal space spot is a double-spot in reality. :-)

    So double spot or triple spot does not really change the Debye-Scherre ring a whole lot. In this case the ring appears "fatter" due to the KAlpha 1 & 2 "doublet". The Rachinger correction will allow the deconvolution of the individual wavelength component.

    Good point about twins and other defects distorting the reciprocal spot further Victor!

    BTW It only took 8-10 frame integration to get these images. At 30 fps, that amounted to about 0.25 sec. It would take a lot longer to carefully pick up a crystal and place it on an optical microscope Vic! It wouldn't be that tough to point the X-ray beam into a clump of crystals stuck on a piece of scotch tape and capture the Laue transmission image in real time.

    Victor! To see how defects affect the reciprocal space data check out these RG posts attached:

  • Melissa Price added an answer in Aquatic Science:
    What are the most important mechanisms for survival of 3-month old white sturgeon?

    Sturgeon biologists - I am studying early life history of white sturgeon (Acipenser transmontanus), and we are in the early stages of building an individual-based model to determine why juveniles do not live past about 6 months of age (recruitment bottleneck). What are your thoughts about the most important mechanisms for survival at this age?

    Melissa Price · United States Geological Survey

    I work with Gulf sturgeon, although the two species are slightly different.  From 6-9 months, the GS YOY are encountering the estuary for the first time and there is increased predation.  Where you are located, you may also want to consider dam impacts and associated hydrological influence.  Ken Sulak (ksulak@usgs.gov) is another good source of information.  Good luck!

  • Nick Asbrock added an answer in Aldehyde Dehydrogenase:
    Could we define the cancer stem cell subpopulation within a cancer cell line solely based on its expression of aldehyde dehydrogenase (ALDH)?

    Read about distinguishing cancer stem cells (CSCs) from its non-CSC counterpart based on stem cell surface markers, such as CD44, CD24, and CD133, is ambiguous and questionable. Is aldehyde dehydrogenase expression in cancer cells the hallmark of cancer stem cells?

    Nick Asbrock · EMD Millipore

    EMD Millipore has recently commercialized a red-shifted fluorescent substrate for aldehyde dehydrogenase (ALDH) that works in a similar fashion as ALDEFLUOR but allows the concurrent use of green fluorescent cell lines, antibodies, transgenic animals and reporter assays.

    www.emdmillipore.com/aldered

    Attached is the Nature publication describing the AldeRed reagent 

  • Emily Ward asked a question in iPSC:
    Struggling to get naive cells not to differentiate after passage number 3?

    I am trying to generate naive human cells from four different iPSC lines but as soon as I get to passage number three they either differentiate or start to die by secreting black debris. 

    Thank you for any advice,

    Emily 

  • Deepak Hiremath added an answer in Antibody Conjugation:
    Does any one have recipe of Biotin blocking buffer for Western blotting using strep-tagII antibody conjugated with HRP ?

    In Western blotting detection i am using strep tagII antibody conjugated with HRP enzyme. This detection some protocol they given biotin blocking reagent. I dont known the composition of Biotin blocking reagent. Please clearly explain what is biotin blocking reagent why we are using ?

    Deepak Hiremath · Southern Illinois University Carbondale

    Well, Biotin is found endogenously in enzymes of mammalian cells and could give background. Biotin blocking reagent is used to reduce the background from such endogenous biotin.  In your protocol,  first of all an excess of unlabeled avidin is added, which binds these endogenous biotinlyated enzymes. Then this avidin is blocked with excess of unlabeled biotin, which will make your sample free from biotin binding sites.

    0.05% avidin and 0.005% biotin in PBS could be used for IHC, I am not sure for western blot. I would recommend you to buy blocking buffer commercially rather than optimizing concentrations.

  • Marziyeh Kheiri asked a question in Health Promotion:
    What is your idea about health promoting hospitals?

    health promotion specialists

    nurses

    doctors

  • Tasnuva Kabir added an answer in Primer:
    Could anybody help in interpreting an abnormal qPCR melting curve for CD34 primer?

    I've got a melting curve showing tow peaks (attached file), a small one before the main one, which is seen in 3 cell lines very similarly while absent in the NTC (no template control). The problem that, the amount of detected gene expression is very low using this primer in a CD34+ cells. Is it necessary to change the primer? and is the CD34 gene is expressed in very low amount? Thanks.

    Tasnuva Kabir · University of Otago

    Have the primer sequences been blasted to ensure amplification of specific product? It obviously looks like off target amplification. If the sequences are binding to non-specific regions even optimising the conditions may not help too much and you may need to redesign new primers. 

  • Nauman Munir added an answer in Damage Detection:
    Anyone familair with damage detection by vibration based condition monitoring?

    In vibration based condition monitoring damage is detected sometime by transformation techniques e.g. wavelet transform or hilbert transform and sometimes we apply outlier analysis or machine learning approaches e.g. Artificial neural networks. I want to know that what is the essence of these approaches? Means when we should go for transformation and when for machine learning approaches for damage detection.

    Nauman Munir · University of Management and Technology (Pakistan)

    thank you very much of all of you

  • Zeljko Stojanov added an answer in Institutionalization:
    Is there any literature supporting that managers in bad institution environments, such as China, tend to make short-sighted decision?

    tell me the titles and the authors.

    Zeljko Stojanov · University of Novi Sad

    You can find articles by using Google Scholar, where you can set your key words, like

    https://scholar.google.com/scholar?q=short-sighted+decision+AND+choice+AND+management&btnG=&hl=en&as_sdt=0%2C5

    Article from my archive - available on Internet:

    Katherine L. Milkman, Todd Rogers, and Max H. Bazerman (2008) Harnessing Our Inner Angels and Demons: What We Have Learned About Want/Should Conflicts and How That Knowledge Can Help Us Reduce Short-Sighted Decision Making. Perspectives on Psychological Science, 3: 324-338.

  • Mazhar Hussain added an answer in Avicel:
    How can I develop good influenza virus plaques using plaque assay?

    Hello everyone,

    I have been using Influenza virus (wsn) and trying to count using plaque assay. But even trying multiple of times, I am getting no plaques at the end. Can you please help me in troubleshooting any problems My protocol is given below (bold):

    Part I. Infection:

    One day before infection

    ·         Seed 1 x 105 MDCK cells in 48-well plate in 0.25 ml of media per well.

    On the day of infection:

    1.       Prepare virus dilution media (SF MEM with 1 µg/ml Trypsin and 0.3% BSA) enough to make serial dilutions (see step 2 below).

    2.       Make 10-fold serial dilutions (10-2, 10-3, 10-4) of virus-containing sample (e.g. media from infected cells, egg allantoic fluid) in virus dilution media.

    3.       Remove the old media from the cells and wash the cells twice with 0.25 ml serum-free MEM.

    4.       Add 125 µl of each dilution to the cells and incubate them for 1h at 35oC.

    5.       Remove the inoculums from the cells and add 0.25 ml of overlay medium per well. [To prepare overlay media, mix equal volumes of 2X MEM and 1.6% Avicel, then add trypsin to final concentration of 1 μg/ml; Mix well to ensure complete homogeneity].

    6.       Incubate the cells at 35oC for maximum 18-20 h. A longer incubation will increase the plaque size


    Part II. Fixation and immuno-staining:

    Fixation:

    1.       Shake the plate gently to reduce the viscosity of the overlay and to facilitate its removal.

    2.       Remove the overlay by suction.

    3.       Add 0.3 ml fixing solution (4% formalin) per well and shake the plate gently to mix the fixing solution with leftover overlay medium.

    [Comment: Usually washing is not required after removing the overlay. However, it is important to make sure that after addition of the fixing solution it is homogeneously distributed in the wells. It should not have big remnants of the overlay left on cells, which would hinder the cells from fixing solution. If this is the case then wash cells once/twice with PBS before adding fixing solution]

    4.       Incubate the cells with fixing solution for 30 min at 4oC (in the cold room).

    5.       Remove the fixing solution and wash plates 2 – 3 times with 0.5 ml/well PBS. Plates can be either stored under PBS at 4oC or immediately processed further.

    Immunostaining:

    1.       Prepare the cell-permeabilization solution (0.5% Triton X-100 with 20 mM Glycine in PBS) and the antibody dilution solution (10% FBS in PBS) enough for all wells (to calculate volumes, see steps 2, 4, and 8 below).

    2.       Add 0.25 ml/well of cell-permeabilization solution and incubate 10 min at room temperature.

    3.       Remove and wash cells twice with PBS (0.25 ml/well).

    4.       Add 0.15 ml/well anti-NP antibody (Millipore #MAB8251) diluted 1:1000 in 10% FBS-PBS.

    5.       Incubate for 1-2 h at room temperature or overnight at 4oC.

    6.       Remove antibody solution and store in 1 ml aliquots at -20oC and reuse once/twice.

    7.       Wash the cells 3 times with PBS (0.25 ml/well).

    8.       Add 0.15 ml/well of HRP-conjugated anti-mouse antibody (1:2000, diluted in 10% FBS-PBS).

    9.       Incubate for 1 h at room temperature.

    10.   Remove antibody and wash 3 – 4 times with PBS (0.25 ml/well).

    11.   Add 0.25 ml/well freshly-prepared substrate, (0.4 mg/ml AEC in sodium acetate buffer + 0.03% H2O2).

    12.   Incubate at room temp for 15-30 min. Monitor appearance of brown plaque staining. Before high background develops, stop the reaction by washing the plate 2 times with 0.5ml/well distilled water. Dry the plate and store it in a dark place.

    13.    Count the plaques against a white background/light and calculate the virus titre by factoring the serial dilution and amount of inoculum (125 µ) added to infect the cells. Scan the plates on a flat-bed scanner for your record.


    Preparation of 1.6% Avicel stock solution

    1.       Disperse 1.6g of Avicel powder in 100 ml distilled water using standard magnetic stirrer.

    One hour stirring at room temperature is sufficient to obtain homogeneous suspension. Make sure that you have no obvious clamps in the Avicel suspension.

    2.       Autoclave at 121oC for 20 min to sterilise the suspension.

    One can prepare a larger volume of Avicel suspension and then aliquot into smaller aliquots before autoclaving.

    3.       Store at room temperature.

    [Comment: Typically, 1.6% Avicel suspensions in water are stable. However, always mix them before use, just to make sure that suspension is homogeneous when you take an aliquot. This is even more important for working dilutions of Avicel, which may be less stable. Thus, you may see precipitation of Avicel in its mixtures with culture media over time. This is normal; just do not forget to mix before use. Mixing is easy (either shake by hand or vortex).]

    Mazhar Hussain · Centre of Excellence in Molecular Biology

    Thank you Thomas for your response...

    I have been using influenza virus for the plaque assay...

  • Ehsan Akafzadeh asked a question in Abaqus:
    "Minor strain" and "Major strain" in "continuum 3D modeling" and "continuum Axisymmetric modeling" In Abaqus...

    hi...In Abaqus,how can calculate "Minor strain" and "Major strain" in "continuum 3D modeling" and "continuum Axisymmetric modeling" (to comparison with FLD diagram) ??

  • Victor Crivianu-Gaita asked a question in SDS-PAGE:
    Am I achieving whole antibody to F(ab)2 cleavage in an efficient manner?

    Hi,

    I am trying to cleave a mouse IgG1 monoclonal antibody to yield its F(ab)2 fragments. Mouse IgG1 is quite resistant to pepsin cleavage, so I have been working with a procedure that makes the antibody more susceptible to pepsin cleavage (PNGase F treatment for 24 hours removing the carbohydrate region on the antibody; adopted from paper "Improved method for pepsinolysis of mouse IgG1 molecules to F(ab)2 fragments"). However, I believe based on what I have seen in the SDS-PAGE analysis of the cleavage of the antibody, that the antibody has become extremely susceptible to pepsin. But I am not 100% certain in this interpretation. I have linked the SDS-PAGE of a 12% gel using a non-reducing loading buffer for a pepsin cleavage of the antibodies. The pepsin was used in a w/w ratio of antibody:pepsin 50:1.

    Band 1: Ladder (180 kda, 115 kda, 82 kda, 64.2 kda (pink), 48.8 kda, 37.1 kda, 25.9 kda, 19.4 kda) 

    Band 2: whole antibody, untreated

    Band 3: whole antibody, post-PNGase F treatment, 0 hour with pepsin

    Band 4: 1 hour with pepsin

    Band 5: 2 hour with pepsin 

    Band 6: 4 hour with pepsin

    Band 7: 6 hour with pepsin

    Band 8: 8 hour with pepsin

    Band 9: 24 hour with pepsin

    Band 10: Ladder

    I see a band between the 115 and 82 kda ladder bands on the gel. Is this band of ~90 kDa my F(ab)2 after pepsin cleavage? I notice that pepsin cleavage is occurring extremely quickly (<1 hour required at this pepsin concentration). Also, there are other bands arising lower that probably correlate to the degradation of the antibody Fc tail. Am I correct in the analysis of this SDS-PAGE gel? 

    I am trying to find the most optimal way of cleaving these antibodies with pepsin (I know I could also use ficin, however, I am very familiar to pepsin cleavage and not so familiar to ficin). Please help me understand my SDS-PAGE and whether or not I need to be lowering the concentration of pepsin I am using as well as am I actually getting my F(ab)2 fragments?

    Regards,

    Victor

  • Ahmed I Gomaa added an answer in Edible Films:
    Which material is better to use for making antimicrobial and antioxidant edible film for food?

    Hello to everyone

    I want to make an antimicrobial and antioxidant edible film for food products but I want to use a material that is inexpensive and highly available for food industry and its construction and other properties is well known for modifications.

    thanks

    Ahmed I Gomaa · Laval University

    I also recommend films of chitosan or pectin containing liposome encapsulated antimicrobials or antioxidants.

  • Marziyeh Kheiri added an answer in Nurses:
    What are the barriers for nurses in doing their roles?

    Nurses have to juggle various roles. A nurse has to act as a caregiver, communicator and a teacher among others. . 

    Most people do not appreciate the real nature of the responsibilities of a nurse. In their eyes, nurses are those who merely administers a shot at the hospital. Others view them as doctors' assistants. Moreover, the media also projects a different image of what they really do. It is worth noting that nurses play various roles concurrently depending on the unique needs of a patient at the time. There are many barriers that prevent them to do their duties.What are the barriers that nurses cannot do their roles?

    Marziyeh Kheiri · Tabriz University of Medical Sciences

    so much thank you master Aghakhani for this question;

    In my idea, nurses who can not do their roles perfectly face to some barriers such as:

    lack of motivation, less knowledge, lack of competency, not being qualified in their field not only in knowledge but also skills.

  • Jose Dolz added an answer in SIFT:
    I want to recognition objects like road traffic signs in a video as method SURF or SIFT. Please, any one idea for that? thank you.

    I want to recognition objects like road traffic signs in a video as method SURF or SIFT. Please, any one idea for that? thank you.

    Jose Dolz · Aquilab

     Still some of them:

  • Quirin Söhnlein added an answer in Exercise Biochemistry:
    What are the biomarkers for the post-exercise damage that we can test in blood or other body liquid ?

    For example we run 5000m, and how can I test the damage that exercise caused to my body?

    For detaily, what are the biomarker responding to exercise damage?

    Would you mind giving me the article?

    Quirin Söhnlein · University of Salzburg

    I really enjoyed reading all those comments to his question. So I just would like to add this experience:

    I work since 4 years now with daily capillary blood measurements (analyzing CK and Urea) and must say that changes in CK DOES NOT reflect muscle damages on midterm or longterm basis.

    CK works very very individually first, and second, running through with CK for various populations of athletes (ghanian, austrian and german soccer players, american, canadian or german ice hockey players), they all show the same pattern. New movements (movements the athletes is not used to do) increases CK a lot and also correlates with a high Borg-scale of muscle soreness. After that, with any known movements the athletes were triggered, they still showed large bore-scales, but only little increase of CK. (as an example, you would have Athlete XX, with a baseline of 300 CK, after 48h-72h of rest, his increase after (training in the morning, measurements in the evening, e.g. 8h post and 24h post) a new intense athletic movement would be around 900 Ck 8h post & 1600 CK 24h post, including a high self reported soreness, the next time he would execute this movement, he would report a high soreness, but an increase in CK of only 650 CK). So we are using CK in a different manner. 

    I hope this gives you an idea how very very very difficult it is to use CK as a predictor for muscle soreness. 

    After all, i would tend to say that even a short-term relation of CK to muscle damage is very questionable.

    Thanks you guys for all those interesting comments. I am very curious about this Xin-thing :-) 

    Best regards,

    Q

  • Aditya Nikam added an answer in Abaqus:
    Can anyone advice on an Abaqus example problem?

    Hello,

    I am trying to run .inp file and .f file from an example in Abaqus Manual. I have attached link to this question!

    I have made the necessary changes to be made in the .inp file as per the instructions provided. However when I run the two files using abaqus j=exa_hydfracture user=exa_hydfracture , there are several files generated but following error is seen in the text file generated. Please suggest!

    Abaqus JOB exa_hydfractureAbaqus 6.14-2Abaqus License Manager checked out the following licenses:Abaqus/Foundation checked out 3 tokens from Flexnet server license2.arsc.edu..Begin Compiling Abaqus/Standard User Subroutines6/28/2015 11:28:12 AMIntel(R) Visual Fortran Intel(R) 64 Compiler XE for applications running on Intel(R) 64, Version 15.0.4.221 Build 20150407Copyright (C) 1985-2015 Intel Corporation. All rights reserved.

    ifort: NOTE: The evaluation period for this product ends on 27-jul-2015 UTC.End Compiling Abaqus/Standard User SubroutinesBegin Linking Abaqus/Standard User Subroutines Creating library standardU.lib and object standardU.expEnd Linking Abaqus/Standard User Subroutines6/28/2015 11:28:15 AMBegin Analysis Input File Processor6/28/2015 11:28:15 AMRun pre.exe6/28/2015 11:28:25 AM Abaqus Error: Analysis Input File Processor exited with an error.Abaqus/Analysis exited with errors

     Thanks,

    Aditya

    Aditya Nikam · University of Alaska Fairbanks

    Thanks Anshul! No one untill now has been so clear in suggestions as you! Thanks a lot. I did try to see the .dat file, but it confused me a little bit. Hence I opened .odb file and tried to directly see the XY data and plot it. I did find options to obtain the graphs, but all I could do is get it versus time instead of distance from wellbore. However, even the one versus time made sense and were logical. 

    Thanks,

    Aditya Nikam

  • Karine Pedneault added an answer in Mite Infestations:
    How do I quantify volatile organic compounds using GC-MS?

    Hello,

    I am trying to quantify a number of volatile organic compounds I have identified in the headspace of mite infested plants. After some reading, I am under the impression that I will need to construct a calibration curve using pure chemicals purchased from chemical vendors. My question is, how do I select a quantifier ion for each chemical and how do I undertake the quantification process?

    Thanks,

    Joe

    Karine Pedneault · Quebec Agrifood Development Centre

    Hi Peter,

    As I mentioned, I screened trough the previous answers so I guess I missed the fact that you stated that Joseph did not need to work in SIM. Sorry about that. However, I would add that, as far as I known, SIM is the proper way to quantify compounds in GC-MS; it is more precise in part because it increases the sensitivity of the instrument, as you mentioned. I haven't test both methods side by side though, as we use a TOF in my team; I would probably give it a try before choosing the Scan mode. 

    Also, I don't know how big Joseph's compounds are (maybe are we talking about C6 leaf volatiles here?), but if they are highly concentrated (e.g. TIC peaks look like "potatoes"), and he can't really reduce the sample size (in headspace or SPME), I would suggest to use lower intensity masses as quantifiers, and work in SIM in order to avoid over-saturating the MS detector with undesirable ions. Higher molecular weight quant masses have more chance to be unique to the analyte. 

    I hope it answers your question.

    Karine

  • Andrzej Antol added an answer in Ecological Statistics:
    How can I compare slopes of 4 lines including repeated measures?

    I would like to compare slopes of four lines, but I would like to take into account that the same animals was measured during the time. The sma procedure in R allows to compare slopes between groups, but there is any possibility to include random effect into the model. Is it possible using other methods?

    Andrzej Antol · Jagiellonian University

    Thank you! It really helped me. I have one more question. Maybe someone can explain me wha actually means when I have higher variance for random effect than residual variance?

    Random effects:
    Groups    Name    Variance Std.Dev.
    malz:dz (Intercept) 1.7693 1.3301
    dz     (Intercept)       0.2535 0.5035
    Residual                  1.5258 1.2352
    Number of obs: 719, groups: malz:dz, 144; dz, 12

  • Abdel-Rahman Akl added an answer in Books:
    What is the best book, paper, chapter, or lecture that talks about history of biomechanics and sports biomechanics?

    I am preparing a part of history of biomechanics and sports biomechanics. The development that occured in equipments, softwares, tools, and methods in varied stages of biomechanics history

    Abdel-Rahman Akl · Alexandria University

    Thanks all for your contributions.

  • Nick Asbrock added an answer in Stem Cells:
    Can anyone recommend a method to get good aldefluor labeling?
    I am working with freshly isolated mouse mammary cells, which I have taken through a standard isolation of organoids to single cells. It seems that all the cells are lighting up and there is ~40% cell kill after the labeling.
    Nick Asbrock · EMD Millipore

    EMD Millipore has recently commercialized a red-shifted fluorescent substrate for aldehyde dehydrogenase (ALDH) that works in a similar fashion as ALDEFLUOR but allows the concurrent use of green fluorescent cell lines, antibodies, transgenic animals and reporter assays.

    www.emdmillipore.com/aldered

    Attached is the Nature publication describing the AldeRed reagent 

  • Abdul Mohin Sajib added an answer in Tagging:
    Can anybody suggest a cheap 6his tagged protein that i can use for western blot?

    I am doing western blot and looking to see band for my his tagged protein...

    Abdul Mohin Sajib · Auburn University

    Thanks a lot

  • Sujay Subbayya Ithychanda added an answer in pH:
    Any possibility to retain enzyme activity at PH 4.5-6, which has optimum PH of 9?

    I Am working with uricase enzyme which has optimum activity at PH 9,But i want to use this enzyme in a reaction mixture of PH 5-6 ,is it possible to retain its maximum activity or at least 70% activity at this PH ,any possibility?

    Sujay Subbayya Ithychanda · Cleveland Clinic, Lerner Research Institute, United States

    Hi Purva,

    You should just do the experiment and find out. Any predicted answer is of no practical value. Suppose I say it may retain >80% activity or <10% activity; it is a guess and you will have to trust me. The good thing about science and experiments is that one need not believe and trust anyone. One can reason and experiment. 

    Good luck with your experiment

  • Nizar Matar added an answer in NMR analysis:
    Who can convert proton or carbon nmr into structure?

    i need someone expert in NMR elucidation of natural compounds urgently if anyone has this expert please sent to me his e-mail urgently thank you

    Nizar Matar · An-Najah National University

    Structure elucidation cannot be done in a hasty manner depending on one tool. When I was a postgraduate student, confirming a structure required :IR spectroscopy, mass spectrometry, NMR spectroscopy (both proton-NMR & C13-NMR), and possibly UV spectroscopy. I am attaching a good (pdf) file , prepared by Bruker, showing examples of how to decide upon a structure when there are various possibilities. My regards.

  • Jose Dolz added an answer in Image Segmentation:
    How can I calculate accuracy of segmented image?

    I have segmented the image and now have to calculate accuracy of segmentation. I have given the original and output image below. Can any one pls help me?

    Jose Dolz · Aquilab

    As stated before, you will need a reference standard to compare with your images. This reference or gold standard must (or should) come from experts if you want to validate your algorithm in clinical context.

    I said experts and no (one) expert because of the inter and intra observer variability. Generating a gold standard for medical image segmentation is quite tricky, particularly in some cases such as brain tumor segmentation (or other types of tumors). Experts usually disagree in contouring tumors, that is why using only contours from one expert would not be sufficient from a clinical point of view. What I would suggest is to take contours from 4-8 experts, and use a consensus (by using STAPLE for example) segmentation to compare with your automated contours.

    As metrics to use, in radiation therapy the following ones are very important:

    • Dice Similarity coefficient. (Volume metric)
    • Volume differences (Volume metric)
    • Some shape similarity metric, such as Hausdorff distances.
    • And perhaps mass center location.

    Some of these parameters might influence the a posteriori dose distribution, which usually is the final goal of the segmentation.

  • Anurag Mohanty added an answer in Physical Metallurgy:
    Why copper layer plated on a steel substrate in (Ar + H2) atmoshphere changes color from brick red to greyish color while heating to 1000 deg Celsius?

    Heating is done via induction method and particles of copper are also found on the quartz tube inside which sample is kept while heating.

    Anurag Mohanty · National Institute of Technology Rourkela

    There was continuous gas sampling from the inlet and outlet making sure that there is no Oxygen present in the gas used.

    I am yet to measure the thickness of the copper film.

    Literature study provides evidence for usage of copper foil at such high temperature in separate Argon and Hydrogen atmosphere whereas plated copper shows different activity. This provides an ample line of thought for the interaction of steel substrate with copper or may be the Argon-Hydrogen atmosphere used which I am unsure about though.

    The purity of Argon and Hydrogen can be accounted for as both show no extra peaks in Mass Spectrometry when used alone.

  • Gopal Singh asked a question in Absorbance:
    What is the correct procedure to calculate fluorescence quantum yield of aggregates if the leveling off tails are high?

    IS IT CORRECT TO Use The absorbance of aggregate solution if the absorbance value is significantly changed/increased due to leveling off tail/mid scattering.

  • Ryan O'Hara added an answer in 3D Printing:
    What are the important journals related to additive manufacturing?

    Hi all,

    for a project on 3D printing I need to find out as many journals as possible related to 3D printing, additive manufacturing and rapid prototyping; i.e. the articles must be mainly on these topics.

    Till now, I have found the following:

    3D Printing and Additive Manufacturing
    Rapid Prototyping Journal
    International Journal of CAD/CAM
    International journal of rapid manufacturing
    RTejournal (Rapid Technology Electronic Journal)
    Virtual and Physical Prototyping

    Also any other reliable sources (scientific magazines etc.) targeting these topics would be appreciated as well.

    Thank you,

    Bartu

    Ryan O'Hara · University at Buffalo, The State University of New York

    Journals that focus on 3D printing will offer insight to the printers and materials. In many other journals, you will find some interesting information about their applications as well.

    http://www.jcmr-online.com/content/15/1/2