Q&A

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  • TSI CPC 3025A: How long does it take until the liquid level LED should illuminate green?

    I want to use a TSI CPC 3025A for some particle measurements. The butanol was removed and the CPC dried for transportation. Now I want to restart the CPC again. Until now the instrument is running for about 3 h but the "liquid level" LED is still off.

    Does anyone of you has some experience on how long it usually takes until the LED should turn on? Or what I can do to check if anything is wrong?

    Martin Brüggemann · Johannes Gutenberg-Universität Mainz

    Thanks for your answer, Avi!

    I managed to get the instrument run. The problem was that there were some air bubbles in the butanol line which prevented a proper function. I removed them by gently pressing the silicon tubing which runs from the butanol bottle to the instrument. Now everything's working perfectly.

    Cheers,

    Martin

  • How can we estimate the DNA concentration using a 1 kb DNA Ladder?

    how can we estimating DNA concentration by 1 kb DNA Ladder?

    Francesco Gobbo · Scuola Normale Superiore di Pisa

    They can just give you an idea, if you are using an appropriate ladder and you load a defined amount of dna solution. https://www.neb.com/products/n3232-1-kb-dna-ladder

  • Is anyone doing KDS to quantify proteins?

    How not to lose protein after centrifugation with KDS?

    Alejandra Aguilar Solis · University of Verona, Cornell University

    HI THERE 

    Yes SDS preceipitation, what is the best way for not to lose protein while washing with KCl

    thanks

  • Farhanullah Khan added an answer in Insect:
    Are there any specific reasons for the frequent development of insect biotypes among the hemipteran group of insects?

    Probably, the higher rate of multiplication in hemipteran insects could be one such reason. But is it really so?

    Farhanullah Khan · University of Karachi

    I think this is because of they are being earlier on the evolutionary process, animals those at the beginning have rapid development, whereas the followers are slow in the ecosystem.

  • Omar A. added an answer in Flavonoids:
    Why does hexane dissolve in water during my flavonoid extraction?

    During my reaction of extracting flavonoids I use hexane in a aqueous methanol crude extract to fractionate hexane and aqueous layer but surprisingly I don't get any layers. The hexane is completely dissolved in the aqueous layer ... is this possible?

    Omar A. · Keele University

    that is possible if you have surface active agents in your extract which incorporate hexane in water as oil/water emulsion or you did mixing in the wrong way as vigorous shaking cause emulsion try to increase the hexane and shake gently in separator funnel how ever we extract flavonoid by aqueous ethanol not by water 

  • Tarun Virabhai Sutaria asked a question in Embryos:
    Embryo preservation technique?

    how the programmable bio freezer works for embryo preservation? how much it costs

  • Johan Frans Prins added an answer in Modern Physics:
    Did Einstein's interpretations of his breakthroughs in 1905 help to derail modern physics?

    Einstein concluded that an electron being ejected by light from a metal only absorbs a quantum of light energy. He also correctly concluded that the Lorentz transformation demands that the speed of light must be the same within all inertial reference frames. Both brilliant insights by a genius!

    I have concluded that he immediately spoiled these brilliant insights by incorrectly deducing that a light-source cannot emit continuously distributed EM energy as allowed by Maxwell's equations; and incorrectly concluded that a clock that moves relative to another clocks must keep time at a slower rate. In addition he incorrectly concluded that a moving rod contracts in length.

    These conclusions by Einstein eventually derailed modern physics to become  the post modern Voodoo that it is at present. I have uploaded a short book here on Researh Gate entitled: "EINSTEIN=GENIUS: But a genius sometimes blunders", in which I explain my arguments.

    It is still in draft format since I would like members of Reseach Gate to review this book and post their arguments on this thread. If you can prove me wrong, please do. I will welcome it, since a true physicist knows that he could be wrong! If you cannot, please confirm that you cannot.

    Johan Frans Prins · Sage Wise 66 (Pty) Ltd

    Dear Andrew,

    You are not arguing physics: Just like Einstein did not argue physics. You do not need clocks and light-signals to define time as Einstein had incorrectly argued. Clocks only measure time and light signals can only be used to. synchronize man-made clocks which are at different positions in space.

    This tells us nothing about the nature of time. It only tells us that it exists since we can measure it. and that it is, without clocks, the same synchronous entity within ALL reference frames in our universe. Everything in the universe must exist simultaneously NOW, NOT simultaneously at different instants in time. The latter is an absurd oxymoron concept with which Einstein bamboozled modern physics. If this were not the case why worry to synchronize man-made clocks when they are not at the same position in space?.  

  • Negin Minaei added an answer in Urban Development:
    What keeps a city/town active or increases activity in urban contexts? Mixed use or an iconic architectural masterpiece (E.g Sydney opera house)?

    Which architectural urban development will benefit in maximizing activities in a city/town like Geelong? Or Torquay?

    Definitely mixed used. An Iconic architecture can attract people and perhaps tourist to visit it once or twice but if nothing interesting is happening in it or in the surrounding area, then just having an iconic architecture is not helpful to attract more people and more activities. Often in the best examples of urban design, an open space with various types of short-term and long-term activities is provided around an iconic architecture. This enables people view that architecture(either it is historical or not)  from different angles within a mixed-use public space which responds to their basic needs such as sitting, eating, drinking, .... So they (iconic architecture+ mixed-use function together) can actually reinforce attracting people and activities in urban environments.

  • What do Next Generation Sequencing services cost?

    Obviously this depends on many variables (strategy, data output, library prep, reads/sample, etc.). If you have paid a platform or company to perform a service, could could you complete this survey so I can have an idea of the costs for various types of sequencing projects:  https://hec.az1.qualtrics.com/SE/?SID=SV_3faIzvc3Ny5FiXH

  • Nishanthi Periyathambi added an answer in Protocols:
    What is the basic protocol for a pfytochemical having anticancer activity and how to confirm it with other protocols?

    I would like to know the methods to isolate the components of a crude extract of a plant and the protocol for its anticancer activity. Where should I start from if i am targeting a particular plant? 

    Nishanthi Periyathambi · Madurai Kamaraj University

    Apologize for error. Its phytochemical...

  • Can anybody suggest a good package for running Data Envelopment Analysis?

    Can anybody suggest a good package to run Data Envelopment Analysis?

    Parag Sen · National Institute of Technology, Durgapur

    I have worked on Data Envelopment Analysis. There is only one good software (which is very easy and user friendly) which I can recommend i.e. DEACheapest

    http://www.cheapestsoft.netai.net/DEACheapest.html

  • Mark E Gould added an answer in Self Concept:
    What do you suggest for an intervention on motivation in an educational context?

    Many children, specially from disadvantaged backgrounds, maintain low self-concepts which in turn feeds back on low motivation for schooling, social interaction and achievement, self-development and self-esteem. My questions goes towards, especially those out in the field who've experienced this kind of powerlessness felt by Psychologists and Teachers, that try so hard and too many times the child's context (family, neighborhood, social economical status, etc.) won't give much support to any educational intervention. What would your recommendations be?

    Mark E Gould · Education Queensland

    Pedro, i don't have a specific intervention, just a mix of motivation theory and 30 years teaching.

    Motivation is usually a blend of intrinsic and forms of extrinsic. The 2 regarded as most valuable are intrinsic and extrinsic where the external motivators are consistent with the students' goals and aspirations. Less important, but relevant are motivation based on rewards, then motivation based on fear and below that amotivation, which is clearly useless. (this is just a rough summary, the theoretical hierarchy is more complex)

    So: interventions that work to develop intrinsic motivation are most important. I work on curriculum development such that the task (and consequent learning) is as useful as possible so that completion of the task is a small pleasure for the student, regardless of the grading process. This helps a bit.

    Next in line, I work on helping students to recognize that their goals align with the learning. Again, with some success.

    Obviously relationships come into play as well. Motivation theory suggests that motivation requires 3 main inputs for the student, They must perceive possibility of success (competence), a sense of control over the process or outcome (autonomy) and a relatedness. So interventions that work to supply these will help.

    You are after general motivation which I don't think is easy. For this to happen students need A LOT of success experiences and a clear sense of alignment of their goals with the course.

  • Farhanullah Khan added an answer in Mosquitoes:
    Can anyone recommend a mosquito sterilization methodology ?

    Can anyone explain the recent techniques available to sterilize mosquito life stages 

    Farhanullah Khan · University of Karachi

    Dear dr. Kitherian Sahayaraj are you thinking to employ any alternate control method simultaneously?
    SIT/SMT is not almost sustainable specially with the mosquitoes there are lot of associated problems as well, if you have a low cost effective plant extract
    • that could cause sterility at low doses when insects are exposed at larval stage
    • has an ability to stay in the open environment longer
    • and has no hazardous effects on non target
    Then you should adopt to use this directly in the fields that control more mosquitos’ species at a low cost. You could get good achievement.

  • Nishanthi Periyathambi added an answer in Sampling:
    What is a simple test to differentiate an unknown sample to see whether its protein sample or DNA?

    What is the simple test to differentiate an unknown sample to see whether its protein sample or DNA? Can I perform Nitric acid test or Absorption Spectra?

    I have a small quantity of sample. In order to identify the sample which test should I take to confirm its a protein or DNA, without wasting the sample quantity?

    Nishanthi Periyathambi · Madurai Kamaraj University

    Thank you everyone

  • Dirk Booysen added an answer in Keratoconus:
    What is role of inflammation in keratoconus?
    Although KC is defined as a non-inflammatory condition it has long been my view that inflammation must play a role in the condition. KC progression is associated with allergy, vigorous eye rubbing, and even contact lens wear. We know that all of these situations can cause inflammation so my question is why has the role of this inflammatory process not been further investigated in the pathogenesis of KC? In our practice we aggressively treat the allergy (and rubbing) associated with KC in an attempt to prevent further progression. So far our results have been good with documented changes in corneal topography and Pentacam scans (although not reported in the literature). Your views on this issue will be appreciated.
    Dirk Booysen · Aston University

    Thanks Omer

    I tend to agree with you and think the process is similar to that of dry eye disease which we now know has a large inflammatory component. Hopefully we can address this and some of the serious consequences of KC

  • Does anyone know why there is no band in RT PCR product on gel ?

    I have extracted RNA from PBMC and prepared cDNA ,I got following results. 260/280 = 1.47  , 260/230 =1.04 , concentration =1040 ng/ug

    but when I use this cDNA for PCR there is no bands on the gel although I have used  high quality reagents and correct annealing temperature .

    Even b-actin as control positive had no band.

  • How do you identify the ability of the practitioner of software project management for efficient decision makings?

    Software project management generally is a process of proper decision makings. Thus, for an experienced person how it is possible to identify this ability as a simple set of criteria to see whether a subject (project manager) has that ability or not. By this question I want to know based on what facts a decision model for a project manager could be an efficient one.

    Raju Chacko · Institute of Electrical and Electronics Engineers

    I've been a Software Project Manager(PM) for quite a few software projects in my career. One objective measure that the PM is good is obtained by tracking the amount of rework/ slippage involved in his/ her projects. The lower the rework and/or slippage in effort, the higher he/she should be rated because if things were perfect/ideal, we should clearly get rework/slippage effort=0! This a kind of 'top-level' or key indicator. Low rework/ slippage values can result only if the PM is experienced, a good manager, one who can handle difficult team-members, has done a thorough job of requirements analysis, has planned correctly, monitors progress effectively and so on. To track rework/ slippage, you need to aggregate time-sheets submitted by team members and compare with planned/ budgeted effort on an ongoing basis.

  • Mer Mercurate asked a question in Cell Line Culture:
    Cell line culture and testing for drug cytotoxicity?

    I started working on cell line cytotoxicity testing for some of my compounds, mainly to determine IC50 on Hela cancer cells.

    I have some question, please advice:

    - I read that we should split cells (into T75), seed cells (to 96 well plates) when the cells are at 70-90% confluent. May i ask why 70-90? Above 90 may not good, but how about below? is that just because <70% we may not have enough cells?

    - How about in your real experiment, i mean the ability to reprocedure? I feel that there are way tooo many factors that may affect the reading.

    Thank you!

  • Aamir Habib added an answer in Cooperatives:
    How can I calculate the channel coefficient in cooperative networks?

    Hello, everybody

    In the cooperative networks, is the channel coefficient from source to a relay calculated by the equation:

    h= sqrt(1 / (D^alpha)) * (1 / sqrt(2)) * (randn + i * randn)

    where D is the distance between source to relay in units of meter.

    alpha is path loss exponent (normally in the range of 2 and 4)

    Aamir Habib · Institute of Space Technology

    it depends how each channel behaves between relay and source is distributed. Also type of fading. is it slow fading or fast fading. No of antennas in the source and the realy.

  • Has any one come across a comprehensive framework to analyse the impact of Corporate Governance Codes in the markets they are applied?

    I'm interested in the effectiveness of Corporate governance codes in emerging markets and will appreciate any framework that can assist in evaluating the outcomes of the codes from a financial or accounting point of view.

    Thanks

       
    Fabrizio Rossi · University of Cassino and Southern Lazio - Italy

    Dear Erick Outa, 

    You can investigate the relationship between the Tobins'Q (and ROA) and corporate governance code, doing analysis before and after the code. Alternatively (or in a complementary way) you can examine the impact of the new rules of corporate governance on the reaction of the stock market.

    I hope my answer can be helpful to you.

    Best,

    Fabrizio

  • Mehdi Belvasi added an answer in Remote Sensing:
    Where can we get current hyperspectral remote sensing images?
    We are planning to develop spectral signature library using hyper spectral remote sensing.
    Mehdi Belvasi · University of Tabriz

    Hi
    Hyperion data can be obtained at

    http://earthexplorer.usgs.gov/

  • Any one knows the vegetable oil soluble Cellulose or Mucilage?

    This requires to prepare a hair Serum a Cosmetic preparation.

  • Giuma Fellah added an answer in Humidity:
    Does anyone know the relationship between the air humidity in a house and the additionnal needs of energy for heating?

    The presence of water in the air makes it more difficult to heat. I am looking for a formula to calculate the additionnal need of energy for heating the house, when the air humidity increase. Or scientific reference that deals with the topic. Thanks!

    Giuma Fellah · University of Tripoli

    Anne: I think you talk about latent heat load, if so, you only need to know the latent heat, humidity ratios and the mass flow rate of the supplied air. The formula can be found in ASHRE or in text books. The attached chapter could be helpful.

  • Miranda Yeoh added an answer in Food Production:
    Is there any viable and innovative solution for the world’s food crisis and food-shortage problems?

    The earth’s population may grow by three billion in the next 50 years or so. The world’s ever-growing number of people points toward a greater demand for food in spite of the already-scarce resources. Famine, hunger and starvation are accordingly a major issue in poor countries worldwide! In your opinion, would the world’s food production/industry suffice to feed the hungry stomachs (given the land and water limitations/scarcity)? What are the world’s options in this respect?

    Thanks so much for your contribution!

    Miranda Yeoh · Kolej Matrikulasi Selangor, MALAYSIA (Selangor Matriculation College)

    Dear Francesca, GM crops cannot save or prevent wastage or greediness.  Those human faults are due to wrong attitudes, and some poor planning.  To prevent waste of food, I need to buy in smaller quantity, and make more trips to the wet market.  And, my normal practice is to cook the leafy vegetables that don't last so well, before the legumes like french beans, and then the vegetables that last well like turnips, pumpkin.  I make it a point to eat more fruits and vegetables (mostly a vegetarian diet) with some fish.  (It's healthier for me to practice this diet, and it's also more efficient because only 10% of the energy can be passed to the next trophic level.)

  • Are there any good stimuli sources for a facial attractiveness research?

    For my master thesis purposes I need a couple of standarized photograpies of masculine faces with diverse level of attractiveness. Does anyone know some open source where I could find them, or should I create the stimuli by myself?

    There was a project in Germany while ago on the perfect face and beauty. Have a look at this website, it may give you an idea what results they got as an average face and virtual attractiveness, social perfection.I am not sure if you use the faces with different facial expressions as mentioned above then you would get the same results. We know every face is nicer with a smile than with an anger expression for example. I think you need to select those faces from the data base that are neutral so you can compare them.

  • What is the best series of solvents for the Fractionation of plant extract ?

    I am going to do a research for the isolation, purification and characterisation of phytochemicals from medicinal plant. I have methanol extract of my medicinal plant. I want to do fractionation. I need a protocol for the series of solvent that can be used one after the other for getting right fractions. Which can be easily purified further by column chromatography. Can any one help me ?

    Is there any other step effective for separation of phytochemicals before starting fractionation of extract like size exclusion chromatography ?

    Gandhidas Sonajirao Lavekar · Central Council for Research in Ayurveda & Siddha

    The above answers are quite adequate no need to add more.

  • Martin Klabusay added an answer in Pancytopenia:
    How do I treat refractory Large granular lymphocytic leukemia with pancytopenias?

    Tried

    Cyclosporin, cyclophosphamide FCM , intolerant to methotrexate

    considering cladiribine and alemtuzumab

    Martin Klabusay · St. Anne´s University Hospital

    Dear Jason, need to know more about the history. Are we dealing with T-LGL or NK-LGL? What was a previous treatment and what is the patient's status. What would be a reason for rituximab use - is there an expression of CD20 on tumor cells? 

  • Girish Avinash Jathar added an answer in Monsoon:
    Are Pseudomonas bacteria living on tropical trees creating monsoon rain clouds?

    I have been observing that when monsoon moisture moves over certain tropical forests located in SE Asia or India, rain clouds with very long streaks form.  Has anyone studied if this is caused by Pseudomonas bacteria that live on particular species of tropical trees, and if so which tree species produce the most rain clouds?  Attached is a satellite image from August 2014 showing these particular clouds forming over the forests along the SW coast of India.

    Girish Avinash Jathar · Watershed Organisation Trust (WOTR)

    Can you share your publications on this subject. We can explore a possibility of collaboration. We are working in northern western ghats on climate change adaptation project. You can know more about us on www.wotr.org

  • Can anyone send me information about ethnobotanical studies conducted in urban settings?

    I have some funds to study traditional knowledge of immigrant groups in urban settings. The references are scarce.

    Gandhidas Sonajirao Lavekar · Central Council for Research in Ayurveda & Siddha

    Please visit the web site of CCRAS -AYUSH Department        www.ccras.nic.in

  • Mehdi Belvasi added an answer in ArcGIS:
    How do you process the data for Width Function in ArcGIS using DEM?

    Width Function is a catchment descriptor like Hypsometric Integral.

    Mehdi Belvasi · University of Tabriz

    Hi

    What process do you want?