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  • What were the biggest engineering structures built in Latin America during the second half of the nineteenth century and who were their designers?

    For example, between 1887 and 1888, in the desert of Atacama (Region of Antofagasta), was built the viaduct of Conchi, that crossed 244 meters over the deep gorge of 102.6 meters high of the river Loa. Its initial design was executed by the New Zealand engineer Josiah Harding and the final design and calculations were done by British engineer Edward Woods.

    Claudio Galeno · Universidad Católica del Norte (Chile)

    Nelson, I like the idea of Basalla of the three phases, and although his ideas are not applicable to all contexts, I think the second stage coincides with my question. Furthermore, the context of Latin American landscapes attractive to large global economies reveals a frame constructions and technology migration that might match the ideas of Gilles and Hughes systems.
    I think your answers have clarified the idea of large engineering structures oriented transport and mobility, such as railways, viaducts, canals, and of course ports.

  • Behnam Ordoubadi added an answer in Ground Motion:
    Which software can normalize ground motion records by pgv (peak ground velocity) as mentioned in FEMA P695?

    I tried to normalized ground motion records by pgv (peak ground velocity) as mentioned in FEMA P695. Does anyone know which software does this normalization?

    Behnam Ordoubadi · Khaje Nasir Toosi University of Technology

    Dear Vahid

    As much as I know there is no software that has a particular module or something to perform this kind of procedures. Normalizing time histories is somehow judgmental and needs to be considered step by step. Plus each code or standard has it own specifications so software can't cover them all.

    Despite all of these, It may be helpful for you to take a look at SeismoSoft collection, some of them are very useful in this matter like SeismoStruct or SeismoSignal.

  • What is the effect of protein to the interaction between DNA and any ligands?

    can any one help to my question. What is  the effect of protein to the interaction between DNA and ligands ?

    Kamran Pooshang Bagheri · Pasteur Institute of Iran (IPI)

    positive charge peptides or proteins could be bind to DNA (plasmid, genomic).

    As an example, cationic antimicrobial peptides can attach to DNA.

  • Marco Grull added an answer in Colony PCR:
    How long is the initial denaturation step for colony PCR?

    I am performing colony PCR using Thermo Scientific's Phusion Hot-Start II polymerase. The manufacturer's instructions recommend an initial denaturation step of 98C for 30s. Should I increase the temperature or length of this initial denaturing to ensure complete cell lysis, and if so what temperature/time should I use? Thanks!

    Marco Grull · Technische Universität Braunschweig

    Which organism are you using??? So I tried to make a kind of colony PCR with clostridium ljungdhalii but i was just able to amplify short fragments in the range of 500 bp. Larger fragments didn´t worked. I think the genomic DNA was fragemented, because when i used a genomic DNA extraction kit it worked.

    So, at the moment I work with S. cerev. and I also need to verify positiv gene integration and when I was searching for a protocol I found this one:


    But so far, I never tried it.  Maybe it will help you. Here in this paper, they discared the supernatant and used the resuspended pellet for the PCR!!  Otherwise, maybe a chloroform/phenol extraction might work. But it is quite time consuming.

  • What is the form of unified force (except gravity) equation as predicted by standard model of particle physics?

    I am not the expert of the subject but have interest in it. It is said that theoretical frame work of the standard model exist which unifies three forces of the nature. here I want to know the form o the unified force equation as predicted by standard model.

    Mohamed El Naschie · Alexandria University

    unification of all fundamental forces except gravity is called GUT short for grand unification.we have two theories. SU5  and SO10  Lie symetry groups based theories

  • Parviz Parvin added an answer in Laser:
    Is it possible to perform some experiment to understand if LASER is based on 3 level or 4 energy level model?

    If it is possible, can anyone suggest an experiment which can allow understanding if laser is based on 3 level or 4 energy level model? For example, for LASER Nd:YVO4. Thank you in advance.

    Parviz Parvin · Amirkabir University of Technology

    "Gain is linear in 4-level system" Alexandr wrote:

    To which parameter is the gain linear? pumping rate, input intensity, or dopant concentration ?

  • Is there research evidence to suggest that educators need to understand the features of technologies before they can use them to enhance learning?

    I'm currently writing a paper and want to present the argument that educators need to understand the types of technologies at their disposal and their various features before they can make discerning technology selection and deployment decisions. However I'm struggling to find evidence for this.

    Does anyone know of any research that substantiates this idea? My paper is on Web 2.0 technologies, but the evidence could stem from any domain.

    Looking forward to hearing from you!


    Alfredo D. Holguín Alfaro · Universidad Privada del Norte (Perú)

    Hi Matt,

    The references have been made in this area are very valuable as they provide evidence of the relationship between availability and use of technologies (software and hardware) and improving learning.
    Be careful when reviewing the evidence, as it shows that the improved learning comes not from the technology itself, but of how we use it in teaching strategies and apendizaje we implemented.
    In essence, you know the equipment or software not give us a big advantage for improving processes but understand very well that is what we seek to occur in the minds of students. For example, the trend is now achieving educational skills and achieve appearing on students is not only technologies but have the power to use them to achieve goals.
    If collaborative skills required, I require a strategy that uses technology resources in a way, if I need communication strategies to use the technologies with some variation.
    In short we need to place the technological tools in the context of education and from there look for the best way to use it, never the contrary, it is to think that mastering technology itself can improve Education.

  • Change in the temperature of electrolyte during anodized TiO2 nanotubes elaboration?

    during the TiO2 nanotubes elaboration by anodization at a potential of 20V.
    is there a change in the temperature of the electrolyte?

  • Ahed Jumah Alkhatib added an answer in Happiness:
    What are your greatest achievements, both personal and professional in 2014?

    The end of the year is the time when we turn around and calculate our achievements, the time of regretting what we have missed out, the time of planning, being happy and being afraid.

    we can always strive for more and better. The ranking lists of the richest, the most influential, most successful come out this time of the year.

    How about You?

    Ahed Jumah Alkhatib · Jordan University of Science and Technology

    I may call this year the year of publication of more than 30 articles

  • Kenneth Hall added an answer in Amazon:
    Why video reviews of products have not taken off on etailer and third party sites like Amazon and Yelp?

    Only a handful of video reviews are available on Amazon though the option to upload video reviews has been there for a long while. (Are there other etailer or independent sites that have more video reviews?) Is it a supply side problem - too much of an effort, even for frequent reviewers, to make a video review? Or is it a demand side problem - not many takers for video reviews? Are video reviews suitable only for product introductions and demonstrations or can they substitute all kinds of reviews? 

    Given a choice between a text review and a video review with exactly the same script for a smartphone or a novel, which one would you prefer as an online shopper?

    Kenneth Hall · Bloomsburg University

    My own experience as an Amazon customer is that doing even text reviews can be a low-grade nuisance. There's no way I'd be bothered to do video reviews. I'd say sellers (or Amazon) could offer incentives for video reviews, but that poses all kinds of potential problems of its own.

  • In your opinion, what is the best book on "History of Cities"?

    I like very much the book (1980) "The History of the City", MIT Press by Leonardo Benévolo, but I would like others indications.

    Thank You very much.

    Irena Benyovsky Latin · Croatian Institute of History

    For medieval period, I would recommend K. Lilley's "Urban life in the Middle Ages"...

  • Vladimir Farber added an answer in Nonlinear Optics:
    Can somebody explain the influence of symmetries on the different order nonlinear susceptibilities?

    I met an explanation similar to what appears in "Nonlinear optics" of Boyd 2ed., but I do not understand physics behind the symmetries.

    Can somebody explain in the simple words the physics behind the symmetries, and how symmetries reduce the number of elements in the high order nonlinear susceptibility?

    Vladimir Farber · Ben-Gurion University of the Negev


    Most of the my knowledge about nonlinear optics is from book of the Boyd.

    I am "understand" what happening in the case of the 2nd order nonlinearity, but when I try apply same concepts on the higher order non-linearity I don't really shure if I do that correct, and I not really understand Kleinman's symmetry in the case of high (for example third or forth) order nonlinearity. Can somebody explain it in the case of the 3rd order nonlinearity? Can somebody explain how mach reduces the number of elements in the high-order nonlinear susceptibility?

  • Does anyone on the role of values in architectural heritage conservation interventions have been studied?

    I'm ready to cooperate and exchange information in this regard, I am working
    A case study in the World Heritage TAKHT-E SOLEYMAN.

    what kind of values are you talking about? historical, identity, social,architectural,...? break it down in details to make it clearer.

  • András Bozsik added an answer in Concrete:
    Would you please name some examples of lost or forgotten knowledge?


    Ancient Roman concrete has withstood the attack by elements for over 2,000 years. 

    András Bozsik · University of Debrecen

    Dear All,

    The mutual respect and politeness, even neat courting as base attitudes of human relationship are vanishing.

  • Adam Patel added an answer in Maxillary Sinus:
    When implant or tooth is pushed into maxillary sinus does one need to remove sinus lining ?

    Pt is completely healthy and sinus is clear no radiological opacity seen.

    Adam Patel · The University of Manchester

    Dear colleague- my understanding here is that you have pushed a tooth which you were extracting into the sinus? OK, here are some important points for consideration:

    1) The tooth is likely to be carrying infection if it was being extracted. This infection can potentially spread to tissues within the sinus

    2) The sinus schniderian membrane has already been breached by the tooth invading the sinus

    3) The tooth cannot be left in the sinus - ideally remove via a caldwell-luc approach pending position of tooth in sinus

    4) A sinusitis (acute) may present symptoms but a chronic sinusitis may develop which can take considerable amount of time

    5) Inform the patient of the occurence - present the remedial options and gain consent for the approach you will take

    Final point: If you would like an answer regarding an implant please post and I will happily advise

    Kind Regards


  • Paul R. Yarnold added an answer in Saw:
    Why my question has been removed?

    about two days ago i asked a question about finding a people in specific research domain. it received about 8 answers. but today i saw that my question has been removed. why?

    Paul R. Yarnold · Optimal Data Analysis LLC

    Dear Andras,

    Everything happens for a reason. Department of Plant Protection--how wonderful.

    My favorite puzzle:

    Question: Where does everything physical that humans possess come from?

    Answer: If it isn’t mined then it’s grown.

    I wish you every success in your research!

  • Haluk Mergen added an answer in Vitamin E:
    Should I reject a paper that has an unreasonablly high OR value?

    I reviewed a paper about a month ago, in which the authors reported the protective of vitamin E against colon cancer was about 50, which is statistically significant.  I knew this could not be correct and as a result, I asked the authors to check their data.   Now, the revision came back and I was told that there was nothing wrong with the data and their data analysis.    I don't know what to do with it.

    Any suggestions?

  • What is the relationship between the values of the architectural heritage and conservation practices there?

    With the goal to be better in the conservation of cultural heritage involved.

    Can you explain your question a bit more, as the relationship seems a direct one. If there is a listed building (an identified heritage) then it needs to be protected and conservation is part of it.

  • Tribhuwan Yadav added an answer in MMS:
    What safety measures are requirement for using methyl methanesulfonate (MMS)?

    MMS is a very dangerous chemical and posses Acute toxicity (oral, dermal, inhalation). how to minimize health risk from MMS during experiments? how volatile is this chemical? and how to deactivate MMS after use? thank you in advance 

    Tribhuwan Yadav · Yale University

    Hello folks .. thank you for you reply... I have MSDS and I know in general precautions, I wanted to know if someone have experience in person and if something else I should also take care of. 

  • Neal McGregor added an answer in Religion:
    Is anyone researching minority religions eg Yazidis, Zorastrians?

    I'm wondering what research is out there - as I am intending to undertake a mini thesis

    Neal McGregor · DeVry University

    Zoroastrianism is one of the world's oldest monotheistic religions. It was founded by the Prophet Zoroaster in ancient Iran approximately 3500 years ago.
    BBC - Religion: Zoroastrianism
    www.bbc.co.uk/religion/.../zoroastrian/British Broadcasting Corporation

  • FTIR spectroscopy for peptides?

    what is the main function of fourier transform infrared spectroscopy for peptides??

  • Can someone help me with Protein Purification using Ni-NTA?

    I am working on a protein, that I tried to express in BL-21 cells. This protein is an integral membrane protein, so I tried harsh buffer conditions to take out this protein in soluble form. The gene responsible for this protein has been cloned in pET28 vector. I am using Ni-NTA to purify this protein, but I am not able to purify it. After purification, I am getting three more proteins of 45, 47 and 47 kDa, with my protein, that is 41kDa. I have used 500uM imidazole for elution, but I didn't get any protein, so I tried 250mM imidazole for elution. Please suggest me, what else I can do to purify it. I can not go for western blot, as we lost this protein primary antibody.

    Tribhuwan Yadav · Yale University

    try to use some other tags.. (MBP or SUMOtag), and also high salt,  these might improve solubility, apart from other suggestions. membrane proteins are very difficult to purify hence you have to play with salt, pH and tags. best of luck

  • Afsana Mahim asked a question in Thermofluor:
    Why did I get totally different melting temperature in ThermoFluor assay?

    I usually do thermoFluor assay with Tris buffer and I use suramin as a positive control for my enzyme to see shift in melting temperature. But when I used PBS instead of Tris buffer, the result is totally different. Usually I get melting temperature  43 degree, with suramin Tm is around 48 degree in tris buffer. When I did the experiment in PBS buffer, melting temperature is 51 degree which is higher than tris condition and there is no melting temperature shift for suramin which I use as positive control for screening my compounds. Does anyone have any suggestion to do my assay effectively for screening coumpounds?

  • Khaled F M Salem added an answer in DNA:
    How much temperature will be suitable to dry leaf samples for preservation without damaging DNA?

    I read few papers and concluded that 21o   temperature  of oven for 48-72 hours is suitable to dry leaves without damaging its chemical ingredients along with genetic materials.

    Khaled F M Salem · Minoufiya University

    Dear Dr Sonu Bharti,

    I would like to thank your question. I have used liquid nitrogen for DNA isolation and is better to get more DNA yield not to face damage when dry your leaf. For that if you keep some fresh leaf at -80C

    with best regards


  • Saeideh Hosseini added an answer in Lignin:
    How can one determine the content of lignin in the solvents by the UV method?

    I want to determine the content of lignin in the solvent by the UV method. But I don't know how to measure the absorbance and in which wavelength. In addition, how can I calculate the content of lignin through the absorbance?

    Saeideh Hosseini · University of Zanjan

    you can see the attached links

  • Hathama Razooki Hasan added an answer in Biosafety:
    Does research of HBx require special biosafety level?

    Recently I am going to do some work on the HBx gene that are widely regarded as an oncogene in HCC.I won't research HBV,but just the fragment for expression of HBx,which doesn't cause hepatitis, I don't know if it requires special attention to the biosafety of the research.

    If there are some experts having experience in researching HBx gene,could you give me some advices?

    Hathama Razooki Hasan · University of Baghdad

    really i do not have the answer. but i were you i will write to bio-safety sector at Sandia laboratory .I think they will help you

  • C. M. Crowley added an answer in Polysaccharide:
    How much is the highest heat DMEM can bear?

    I was asked to dissolve one kind of polysaccharide in low glucose DMEM without serum and apply it to HepG2 cells. But the polysaccharide is difficult to dissolve and I have already tried ultrasonic but it doesn't work. And now I try to use water bath to dissolve the polysaccharide. Does anyone know what's the highest temperature DMEM can bear? 

    Thank you sooooo much.

    C. M. Crowley · University of Limerick

    What I would suggest that you do is buy a  concentrated DMEM (Sigma-Aldrich sell a 10x DMEM http://www.sigmaaldrich.com/catalog/product/sigma/d2429?lang=en&region=IE other companies will supply an equivalent).  

    You don't say what polysaccaride you are dissolving (mwt will have a huge impact on time required for dissolution) but I would not recommend that you go > 50 dC as you may start to degrade in fact I would have dissolved mucopolysaccharides at 4 dC but this required > 30 hrs for complete dissolution.  Have a look at this for an idea:


    Dissolve your polysaccharide (you may need to sterilise this beforehand) in sterile TC water (must be sterile remember sugar solutions will happily support bacterial and fungal growth - alternatively sterile filter your polysaccharide solution prior to adding to DMEM) and then dilute your concentrated DMEM with the polysaccharide solution     

    The advantage of doing it this way is that you can control how you prepare your polysaccharide, check it's thermal stability prior to adding to your cell culture media (viscosity measurements or GPC) and sterile filter.

    Hope this helps 

  • Ronny Khalil asked a question in Diy:
    What is/are the likely reason(s) for the separation of the fluorescent DiI and LDL?

    Hello everyone, 

    I made low density lipoprotein (LDL) labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) and prepared for macrophage like cells (P388D) for uptake. The results were a bit strange, as the LDL was internalized by the cells, while the DiI was stuch in the membrane. It seems that they dissociated at some point.

    Any ideas what is/are the cause(s)?

    Thank you in advance

  • Kamran Pooshang Bagheri added an answer in His-Tag:
    Is it possible to produce an 8-kDa recombinant protein(with His tag) in E.coli ?


    Is it possible to produce an 8-kDa recombinant protein(with His tag) in E.coli ?

    Kamran Pooshang Bagheri · Pasteur Institute of Iran (IPI)

    Yes, recombinant peptides are produced in bacterial hosts with and without His tag.

  • Tanmoy Majumder asked a question in Electrodes:
    What is the difference between two electrode and three electrode photoelectrochemical characterization?

    I have done two and three electrode characterization of same material, but results is different.

    Which characterization is better?