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  • Mehdi Osooli asked a question in Limit Analysis:
    How to crreat a variable that counts various visits with the time order?

    I have a dataset with multiple visits recorded for patients. I want to use only data from enrollment for an analysis. How can I code so I limit the analysis for the enrollment visit? 

  • Ruth Serra-Moreno asked a question in SUMOylation:
    SUMOylation assays: have you used abcam ab32518 kit?

    I am going to use the abcam sumoylation kit ab32518, and I was wondering if someone ever used it with cellular extracts cottoning a putative E3 SUMO ligase. IF so, how much input lysate (concentration) should I use?

  • Seyed Alireza Pakdaman Shahri asked a question in MATLAB:
    What does it mean that the cut-off frequency be normalized by the sampling frequency?

    There is a low pass filter . And my sampling frequency is fs. 

    the Matlab code of the lpf is as follows:

    % y = LPFilter(x,fc),
    % Second order zero-phase Lowpass filter
    % inputs:
    % x: vector or matrix of input data (channels x samples)
    % fc: -3dB cut-off frequency normalized by the sampling frequency
    % output:
    % y: vector or matrix of filtered data (channels x samples)

    In the code fc (cut-off frequency) is replaced by 0.7/fs . Can anyone explain why fc is replaced by 0.7/fs ?

  • Md. Sarwar Hossain added an answer in Sustainable Development:
    #‎Sustainable‬ ‪#‎Development‬ ‪#‎Goals‬- No poverty... is it sustainable ?


    Md. Sarwar Hossain

    in case of absolute poverty, despite increasing trends of global average human wellbeing, the inequality is also becoming higher ! When we can not reduce poverty for farmers who are feeding us around the globe, zero poverty is not possible in both relative and absolute sense. Evidences from Bangladesh and India- the farmers sufferings still questioning that are we measure the MDGs and SDGs in an effective way?

  • Raul Cevallos added an answer in Sertraline:
    Is there an effective pharmacological treatment of depressive symptoms in dementia?

    A recent research published has shown that Sertraline and Mirtazapine are ineffective for depressive symptoms in patients with dementia. What alternatives do we have?

    Raul Cevallos

    Thank you so much Beatrice

  • Didier Fesquet added an answer in Ultracentrifugation:
    Why does my protein not appear both pellet and supernatant in SDS-PAGE after ultracentrifugation (30.000 rpm 1h)?

    I try production a recombinant protein (about 42 kDa). After induction, the protein appear in SDS-PAGE. When I disruption cell (E.coli) with sonicate, the protein appear in SDS-PADE. But after ultracentrifugation (30.000 rpm 1h), the protein don't appear both pellet and supernatant in SDS-PAGE. I try again with extra protease cocktail but its same.
    What do you think the problem ?

    Didier Fesquet

    If you use 6his tagged prot...extract ypur prot underdenaturing 8M urea condition and keep the denaturant until the elution ..this way you are sure any residual protease is killed..and you must easely see your prot

  • Kenneth C. Carroll added an answer in MODFLOW:
    Could anyone introduce to me some scientifically proven groundwater flow models?

    As you know, MODFLOW is the most reputed groundwater model presented by USGS; however, I want to know some less reputed models that use other algorithms such as FEM. Moreover, it is important if they are easy to use and have a better user interface than the MODFLOW.

    Kenneth C. Carroll

    FEFLOW is a FEM based groundwater model.


  • David B. Saint John added an answer in 3D Printer:
    May i know the most significant parameter effect on Part strength using FDM 3D printer process?

    new research study on part strength using 3D printing process.

    David B. Saint John

    Great Question.   I don't know that we're at the point where I can definitively say what is most critical, but extrusion temperature and infill orientation/design can play a big role.  It is to some degree dependent on the design of object in question and the loads which will be applied to it.  With a standard tensile sample, for example, the exact way in which the infill is patterned around the neck can contribute to a weaker or stronger sample, with some infill settings working better than others.  

    Ultimately, it should be remembered that all FDM/FFF parts are very defective in comparison to injection molded components, as there is almost always some built-in porosity which cannot be removed.  

    My student Joe Bartolai is working on this at the moment - I'm hoping that we will be able to say more as he progresses.

  • Didier Fesquet added an answer in dsRNA:
    Is HPLC purification necessary for dsRNA synthesis?

    I have to order dsRNA (25nt) and I asked for a quote. The supplier insert HPLC purification that is very expensive. I would like to know if it's strictly necessary. No HPLC purification would affect negatively my experiment?

    Didier Fesquet

    no need of purification ...I simply use desalted siRNA . it work great .

    in europe: eurogentec, eurofins provide good quality siRNA

    beware of what the company claim..if they have real synthesis skills

  • Roberto Angeletti added an answer in 3D-Imaging:
    What is the best software to convert 2D images to 3D virtual images?
    I am good doing pictures for video games and I would like show my images in 3D environment. What is the best procedure for converting my drawings to 3D?
    Roberto Angeletti

    Sure, the best program to convert 2D photo images in a 3D tin model is Agisoft PhotoScan.  Only, you need more than 3 images to use it, and obtain a good 3D model.

    More, photos need to be taken in a sequence, for example with two frame per second, moving the camera along a path.  Search for it with Google, an you will find the complete demo of PhotoScan basic, sufficient to try with your images.

  • Didier Fesquet added an answer in Molecular Weight:
    Stripping membrane with low molecular weight proteins (<30kDa)? Western blot?

    We currently use restore stripping bufferhttps://www.thermofisher.com/order/catalog/product/21059[1]

    which we usually incubate for 10-15 minutes to strip. But for lower molecular weight proteins, we usually dont even botehr beacuse we know it'll just pull it off.

    If i incubated it for like 5 minutes, would that suffice? Does anyone have experience with this. We have two proteins at 27 and 24kDa, same species so its tough. 

    Didier Fesquet

    you probably mean sodim azide to kill HRP. (this is the way I do when stripping is not convenient/necessary) ..H2O2 is a component of the "ECL" reagent!

  • Gilles Maussion added an answer in Primary Neuronal Cultures:
    Is there any specific way to Isolate NR2A and NR2B Protein?

    To see the NMDA receptor subunit NR2A and NR2B protein how could i isolate protein for western blot from primary neuronal culture although i isolate the total protein but the expression of this NR2A and NR2B protein is little bit low at 14 days of culture ......

    Gilles Maussion

    Dear Nazmul,

    As I understand, you want to observe NR2A and NR2B proteic expression level.

    To determine if your western blot is working, maybe you could add positive control like mouse or rat adult brain?

    As you are working on primary culture neurons, the expression might also be dependent on the developmental stage your start your primary culture. Starting later could help.

    finally, you should have first a better sensitivity at checking both mRNA expression level prior to protein.



  • Ammar Sarwar added an answer in Drug Information:
    Which are the resources from where we can get the updated list of OTC drugs in India?

    Which are the resources from where we can get the updated list of OTC drugs in India?

    Ammar Sarwar

    You may consult British National Formulary (BNF) for this purpose.

  • Virendra Kumar Saxena added an answer in Groundwater:
    What are the main characteristic of groundwater?

    what are the main characteristic of groundwater?

    Virendra Kumar Saxena

    The main charecteristics of groundwater is as follows : 

    1. Physical :  colour, taste, smell, temperature.

    2. Chemical :  pH, Specific Conductivity, Total dissolved Solids, Total suspended solids,   Total Hardness, SiO2. Na, K, Ca, Mg, HCO3, Cl, SO4, F, NO3, NH3, trace elements etc.

    3. Biological : colliform bacteria, allage etc. 

  • Ozlem Kaplan asked a question in Vectorization:
    Can pBAD vectors express in E.coli BL21 (plySE) or E.coli DH5alpha strains?


    I will try expression with pBAD vector system first time. It's recommended to use E.coli TOP10 or LMG194 strain. But there aren't this strain in our lab. I investigate the expression system. Can I use E.coli BL21 (plySE) or E.coli DH5alpha strains for you? Do you have experience in this regard ?

  • Mikhail Temnov added an answer in Microalgae:
    Press or extractor to extract lipids from the biomass of microalgae?

    Good afternoon! What are the industrial extractors for extracting lipids from the biomass of microalgae? Where can I read about it? I have found just such a project for the extraction of lipids, but I do not have an idea or industrial project.And I found a video where the press used to extract oil from biomass mikrovodrosley.
    What can I read the article on this subject?

    + 2 more attachments

    Mikhail Temnov

    Sushanta Kumar Saha, thank you very much!

  • Nidhi Kushwaha asked a question in Data:
    Data mining on imbalanced dataset of Recommender Systems.

    Hello all,
    Pls. tell me how to do data mining on imbalanced dataset of Recommender Systems.
    As per my knowledge one need to create training and testing files for each user, having their ratings as the class label. For Ex:
    Suppose user have given Item1, Item4 and Item3 rating 5, 5 and1 respectively and we want to predict his rating for Item6
    For a user1 the training data will be:
    // User1_F1 (shows the feature of user1) & Item3_F1 (shows the feature of item3) and so on...

    testing data will be:
    Please correct me if i am wrong....
    Here,as we can see class label 1 comes only one time but class 5 comes two times, how to remove this imbalanced dataset problem?
    And also tell me how to handle imbalanced data or any tool that can do pre-processing before applying Data Mining techniques on this data?

  • Monsur Ahmed asked a question in Semiconductor:
    How quantum confinement works?

    situation of discrete energy levels is called quantum confinement but how it works on semiconductor. What is its advantages?

  • Goutham Genomics added an answer in Cancer Cells:
    Is there any common markers one can use to sort cancer stem cells from HCC827, MDA-MB-468 and A-498?

    Hi, Is there any common markers one can use to sort cancer stem cells from HCC827( lung cancer cell), MDA-MB-468(TNBC) and A-498 (Renal cancer), any suggestions? Thank you!

    Goutham Genomics

    Hello Sreeja

    The most used markes would be CD44 and CD24 . CSC's are bascially CD44 positive and CD 24 negative. One can sort the cells using FACS and get an aliquot of it back to lab and grow. But optimizing media and culture conditions are always tedious with CSC's on flask from our lab experience.

    If you wish to get higher populations of CSC with in any cancer cell line one can use specific growth factor supplements like EGF, FGF, b27 supplement which are strongly reported to increase cancer stem cell population. From our experience a 3 fold to  5 fold increase in CSC's population was observed after enrichment. This could help u to sort minimum amount of cells that can regrow in flask.

    Any other queries please feel free to ask, We have worked on breast cancer stem cells (MCF-7 and MDA MB 453) sorting culture maintenance and molecular work associated .

  • Jaspreet Kaur asked a question in Power:
    Interpretations from wavelet analysis?

    Hi All,

    I am doing the multivariate wavelet analysis of ecological time series in R. I have a hard time interpreting the graphical output I am getting. Please find attached one of the graph from my analysis. The graph is a plot of results from whites of two time series. I have the following questions regarding the analysis;

    1. I know what the statistical power means, but, is the power in attached plot same as the statistical power ?

    2. What can we conclude about the contours with 95% confidence but low power?

    3. Is there any way to quantify the differences between two time series ? I am doing clustering of time series and getting distances from 100 to 300 between different time series. I don’t know how to interpret these distances. How much distance is required to consider the two time series different ?

    4. How to interpret different periods on the plot ?

    5. Should we completely ignore the regions on plot that are outside 95% contours but in phase ?



  • G. G. J. Ernst added an answer in Oxygen Isotopes:
    Have accretionary lapilli (dense ash aggregates) been sampled and studied immediately upon landing on the ground ?

    Hello everyone,

    I asked a previous question as to whether dense ash aggregates (or "acc-laps") have ever been made in any wind tunnel lab thus far in their fully formed sub-spherical or ellipsoïdal shape ?

    The answer has been: "not yet", even though this would allow to more closely simulate mixed phase aggregation under more realistic in situ ashcloud conditions.

    I am wondering if any accretionary lapilli greater than about 10mm across or so have ever been collected immediately upon reaching the ground and studied immediately, or preserved in a cold box (to prevent them from any melting) and studied in the lab (eg. on a cryogenic SEM stage, or to measure their in situ temperature, and recover inner fluids from the intergranular space....) ?

    The reason is that there is the hypothesis that they form like hailstones by riming, once they grow above a size characteristic of the drop break-up limit (5-6mm across). If this "volcanogenic hailstone" hypothesis is correct, then my expectation is that a proportion of accretionary lapilli larger than about 6mm diameter should still be frozen upon reaching the ground (especially if above-ground températures are close to 0°C; if not partial melting takes place), so that somewhat larger ones (say 10mm diameter ones) may still be frozen (despite partial melting) and still contain inner ice upon landing on the ground.

    Has anyone checked for this ?

    Assuming for a moment that larger sub-concentric acclaps can be sampled immediately, preserved and analysed for oxygen isotopes of any trapped ice water, then this could provide valuable data as to the temperature environments through which the acc-laps have been recycled again and again in the volcanic cloud before ultimately falling out.

    Analogous oxygen isotope ratio studies  of the subconcentric layers of hailstones from severe thunderstorms have provided such information in that case.

    I am looking forward to hearing back.

    Best wishes and kind regards,


    G. G. J. Ernst

    Dear Ulrich,

    Thank you for the helpful reply and diverse infos. I shall look into all of it.

    I just want to clarify in which case freezing appears necessary to me.

    Ash aggregation can occur in a variety of context:

    1. In hot dense fluidized pyroclastic flows. Clearly no ice here.

    2. In Surtseyan deposits such as those described by Volker, armoured lapilli form (acc-laps can also form...). As discussed in the 2 previous exchanges, here no need for freezing of any kind to account for the armoured lapilli.

    3. In clouds ascending above base surges or above pyroclastic flows generally (co-ignimbrite clouds) or in the case of ascending vertical clouds above vent, ash aggregation also takes place and the ash aggregates then fall out.

    If the atmosphere is pretty dry, low density electrostatically-bound ash clusters are produced (work by Mike James, etc..).

    If the cloud is water vapour rich or if the atmosphere is moist, dense ash aggregates are observed.

    By wet accretion, ash aggregates or water drops (to produce rain) cannot grow to a size exceeding 5-6mm diameter, from the classic cloud physics literature.

    The reason is a hydrodynamic instability. Shear drag forces tear these large drops apart. The break-up probability increases exponentially as size increases and no stable drop can exist above 6mm. So if ash-filled drops are not frozen a little before reaching the drop break-up limit, dense ash aggregates exceeding 6mm across are not expected to be able to form. They cannot form by wet accretion above 6mm across.

    It is in that case that I believe freezing and growth by riming as in hailstone formation takes over at that point. Besides I presented numerous observations and measurements consistent with this growth model during the IAVCEI 2004 international conference in Chile. This is already very long ago.

    I am of course curious about your observations at Tungurahua and shall look them up.

    Great many thanks.

    Best wishes and kindest regards,


  • Ashraf Ashraf asked a question in MATLAB:
    Can any one help me about static var compensator matlab model ?

    Can any one help me about static var compensator matlab model ?

  • Marion G Ceruti added an answer in Isolation:
    Other than their isolation, what, if anything, do language isolates have in common?

    For example, languages that are considered "isolates" include Ainu, Basque, Kusunda, Nihali, Sumarian, and Zuni. Languages have many characteristics that could serve as areas of comparison, such as pronunciation, grammar, and spelling. Has any linguist performed a systematic study in search of similarities along any dimension?

    Marion G Ceruti

    Hello Joachim,

    Great post. Thank you very much.

    Best regards,


  • Gilles Maussion added an answer in MCF-7 Cells:
    Can you help me about micro RNA mimic transfection and negative control?

    I want to transfect 10 nM, 20 nM and 30 nM of miR145 mimic to MCF-7 cell line. Then I want to transfect a plasmid containing miR 145 target sequences at the end of my gene. I want to evaluate expression my gene versus miR 145 concentrations (10 nM, 20 nM and 30 nM).
    I have two question?
    1. Using miR negative control is necessary for this test?
    2. It is necessary using 10 nM, 20 nM and 30 nM of miR negative control or I can use from one concentration?

    Gilles Maussion

    Dear Mohammad,

    For your experiment to be well design, you would need 1) a miR negative control, basically a scramble mimic that does not match with any sequence of the genome you are working on.

    Then your transfection will be controled for transfecting an oligonucleotide in the cells.

    It would be better to would also be ideal to use the same concentrations for both condition, then you could determine which of those might be effective or toxic for the cells.

    Ideally you could also have a control where you treat your cells with the transfectant but not the oligonucleotides.



  • Arjun Pady asked a question in Streptomyces:
    Best Method fro extraction of genomic DNA from Streptomyces spp for PCR?

    For PCR purposes, we have prepared an axenic spore stock of the desired characteristic-based mutant. 

    Please provide a link/reference to Article where applicable!


  • Mahin Gholipour added an answer in Trizol:
    Esophageal tissue RNA extraction or RNA seq?

    Do you have experience in esophageal tissue RNA extraction(with Trizole) for RNA seq?What is your protocol?If the sample of esophageal tissue is small which way is preferred, pellet mixer or mortar?   

    Mahin Gholipour

    Dear friends 

    Thank you for your comments. My samples are small and homogenization of samples is important problem in RNA extraction of tissues. I tried pellet mixer and mortar for extraction. I think pellet mixer is better than mortar in small samples. Unfortunately the OD of RNA which were extracted not good so, the experiment is very important. If you have a protocol which could help me extract RNA with better OD please send me .

  • D. V. Grigoriev added an answer in Mosasaurs:
    How to distinguish mosasaurian teeth from crocodilian?

    Mosasaurs have different types of teeth (see attached figure from Bardet et. al, 2014.)

    But so do crocodiles...So, How to distinguish  in general mosasaurian teeth from crocodilian? (for example the first picture shows Crocodyliformes tooth, and the second Prognathodon sp. (Mosasauridae))

    + 2 more attachments

    D. V. Grigoriev

    Thanks a lot!

  • Mohamad Amin Kaviani added an answer in Uncertainty:
    Which is the best technique to solve problems under uncertainty?

    I am researching about decision making in agricultural planning under uncertainty.

    Mohamad Amin Kaviani

    I think you can use decision making methods (MCDM methods) under these environments: 

    Fuzzy-  type-2 fuzzy- Intuitionistic fuzzy- Grey, You can use also fuzzy-grey hybrid situation.

    In the field of agriculture planning you may see these papers:

    1- Vermeulen, S. J., Challinor, A. J., Thornton, P. K., Campbell, B. M., Eriyagama, N., Vervoort, J. M., ... & Smith, D. R. (2013). Addressing uncertainty in adaptation planning for agriculture. Proceedings of the National Academy of Sciences, 110(21), 8357-8362.

    2- Yu, J., & Zhu, Q. (2015, June). Agriculture production planning under supply uncertainty and demand uncertainty. In Service Systems and Service Management (ICSSSM), 2015 12th International Conference on (pp. 1-3). IEEE.

    Hope that my answer can help you.

  • Katrina Darr added an answer in Design For Test:
    How do you create an experimental design to show that mRNA is being degraded?

    I need an experimental design to test if mRNA is being degraded.

    Katrina Darr

    I am hypothesizing that an unknown ER associated misfolded protein will be retrogated into th cytosol for degradation and need to design 2 experiments to test this.