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  • Sean C Thomas added an answer in Forestry:
    Are there empirical evidences to prove that the rain forests are actually the lungs of the earth?

    I am a researcher with interest in environmental forestry. It is often said that 'the rain forests are the lungs of the earth'. I will like to know if there are empirical evidences to buttress that assertion.

    Sean C Thomas

    Unless one drastically redefines the meaning of "lung", rain forests (here I presume you refer to tropical rain forests) are NOT the "lungs of the earth". 

    Although rain forests (and other ecosystems) do exchange oxygen with the atmosphere at a molar ratio very close to that of carbon dioxide, oxygen makes up ~21% of the atmosphere, so the pool of atmospheric oxygen is enormous.  There is thus almost no effect on oxygen concentrations of the annual variation in oxygen exchange.  During geological periods when tropical rain forests were much reduced (such as recent glacial maxima) oxygen levels were very similar to current values.

    There is a clear statement debunking the "lungs of the world" argument on p. 183 of J. Ghazoul and D. Sheil (2010) "Tropical rain forest ecology, diversity, and conservation", Oxford University Press.

  • Robert C. Baumann added an answer in Insulation:
    How effective is vacuum insulation at high temperatures?

    Hi All,

    I am trying to assess feasibility to store energy as heat. Now, not to loose too much, it needs to be insulated, by eg a double-walled steel tank, with vacuum between both tanks, and filled with some cheap insulation material, like basalt wool.

    Can anybody help me how efficient this would be at hot ?. The highest temperature possible with cheap steel is about 500 degC.

    Best Regards,


    Robert C. Baumann

    Radiative transfer will not be effected by "fill" with the exception of the fill being able to reflect back the radiation. Rock wool is a good insulator because of the air trapped between the fine fibrous structure - if you remove the air it does not do much and may increase thermal loss due to conduction. Any material you put between the inner and outer tanks will basically do three things with the radiation emitted by the inner tank: reflect it back, absorb it, or transmit it. In the last two, the radiated energy is lost to the out wall and hence the wool has done nothing to reduce the heat loss by radiation.  In the first case, the reflection case, there might be some hope if you could find a perfect reflector and hope that the inner tank was a perfect absorber but these types of materials only exist in the imagination.

    To answer your question, my guess is that the two tank solution would lose heat very quickly with air between them. A little less quickly with a high vacuum between the two, and adding rock wool would likely increase thermal conduction while doing nothing or very little to stop radiation emitted by the inner tank.

    Just an educated guess...Good luck with your project.

  • Benjamin Cassen Macneille asked a question in QIIME:
    Qiime: alpha diversity and default mc2?

    To calculate alpha diversity and rarefaction curves, singleton counts should be included, but qiime's default removes them in pick_open_reference. Does qiime treat the doubletons as singtons for the rarefaction curve?


  • Ruth Nebel asked a question in Synchronization:
    Study partner? Teeth are the tool tosynchronize the body to space?

    Would somebody like to take part in an examination if teeth are the tool to synchronize the body to the spatial dimensions and gravitational direction (synchronization is supposed to be superior to spatial orientation)? The findings should reveal if it is the spatial orientation of teeth that affects body posture after a dental change. This should open up an approach to cure patients from dentally caused body pain. It should be interesting for other medical disciplines, too. I suggest a pilot study with 24 probands. There will be needed an access to a gait laboratory with 3 D camera system for 2 days. If someone has got the possibility (Europe or other), please write to: ruth.nebel@mail.de

  • Morgan Preziosi added an answer in RNA Isolation:
    Does anyone have a good protocol to isolate RNA from liver sinusoidal endothelial cells?

    I am trying since months to isolate RNA from mouse liver sinusoidal endothelial cells. I tried Trizol as well as Qiagen micro/mini columns and with different amount of cells (from 1 mios to 5 mios) without any success. Does anyone have some advice for me? Thanks 

    Morgan Preziosi

    Hope you have solved the problem! If not, see the attached paper. I have had the same problem with endothelial cells and came across this, hoping it will help me as well.


  • Zaagane Mansour asked a question in Earthquake:
    Can the same seismogenic fault generete a futur eathquake, and what about the energy accumulation along a fault ?

    seismic, fault, earthquake

  • Mohammad T. Raad added an answer in Nanotubes:
    How can I calculate dispersion energy at the interaction of gas molecule with nanotube?

    How can I calculate dispersion energy in the interaction of gas molecule with nanotube by gamess software?

    Mohammad T. Raad

    We can calculate an empirical (Grimme's like) dispersion.

  • Chithan C Kandaswami added an answer in Natural Product Research:
    Are the bioactive molecules from plants grown in arid regions different from the plants grown in temperate region?

    There are numerous bioactives reported from plants in literature. However, there is no clear comparison between the ones derived from plants growing in arid region compared to ones derived from plants growing in temperate region. Can anyone give in some comments.

    Chithan C Kandaswami

    Dear Gurpreet,

    <Are the bioactive molecules from plants grown in arid regions different from the plants grown in temperate region?> There may be qualitative differences in terms of the molecules elaborated by plants in these two different regions. Then there is also an issue of phytochemicals originating in the semi-arid zone. Phytochemicals occur in massive numbers; it is like an army (a legion). Categorizing bioactive constituents of arid region plants may be a Herculean task. The prospect of identifying robust and potent bioactive compounds from arid zones with potential prophylactic and therapeutic actions could spur increased exploration.

    Bioactive compounds produced by plants as secondary metabolites comprise phenolics, alkaloids and terpenes/steroids (phenolics constitute about 50%, alkaloids 18 %, terpenes/steroids 27% and others 10%). Non-starch poly saccharides (cellulose, hemicellulose, gums, mucilages, pectins, lignins) also are bioactive; they possess water holding capacity, cause delay in nutrient absorption, bind potential toxins and bile acids. Phytochemical dictionary has some 3,000 entries encompassing 1) carbohydrates and lipids (2) nitrogen-containing compounds - excluding alkaloids (3) alkaloids (4) phenolics and (5) terpenoids/steroids. Approximately 25,000 types of terpenes and terpenoids, 12,000 types of alkaloids and more than 8,200 (as of the year 2000, most likely a fraction of the total number of flavonoid molecules that may exist in nature) types of flavonoids are known.

    Phytochemical dictionary. A handbook of bioactive compounds from plants.  Harborne, J. B.;Baxter, H. Book: Phytochemical dictionary. A handbook of bioactive compounds from plants. 1993 pp. viii + 791 pp.  ISBN 0-85066-736-4. Harborne,  J.R. (1993).   Introduction to Ecological Biochemistry, fourth ed.  Academic  Press, Elsevier, London, pp. 1–32

    Plants that grow on low nutrient soils and under harsh climatic conditions (extreme temperatures, intense solar radiation, and water scarcity) are specifically susceptible to oxidant stress (reactive oxygen and nitrogen species. They have evolved efficient antioxidant defense systems.  Desert plants seem to particularly elaborate bioactive molecules protecting them against the `ravages of a harsh environment.  Some of these molecules may be unique in their nature.The same defensive secondary metabolites may also have a protective role against cancer and degenerative disorders.  Plants adapted to arid climate and harsh environment may synthesize powerful UV screens (protective molecules such as anthocyanins). 

    In considering the possible differences in phytochemicals between arid and temperate regions one needs to take into consideration the symbiosis between plants and microbes. It has become clear that a significant portion number of bioactive natural products are in fact elaborated by associated microbes and/or through interaction with their host. The nature of phytochemicals thus synthesized in arid region plants would depend on their microbiomes.    

  • Ismael A. Justo added an answer in Cement Mortars:
    Is there other dependable test I can use to obtain the porosity in a cement mortar instead of using the Mercury Intrusion Porosimetry (MIP) ?

    The cement mortar is considering normal cement, Ottawa sand and water.

    Ismael A. Justo

    Thanks José, I will look for that indirect technique with SEM to see pros and cons and then decide how to obtain that porosity value of my cement mortars.

  • Petr Vanicek added an answer in Variability:
    What are different methods to measure variability between two datasets containing the same variable?

    I have a data set (1) contain the values of a variable with

    a mean of 2.65, a standard deviation of 18.13, min. of -51.73 and max. of 54.39 compare with another data set (2) containing the same variable, but

    a mean of 2.65 ,a standard deviation of 18.12,min. of -51.65 and max. of 54.35

    How to Measure Variability between them to choose the best

    Petr Vanicek

    It depends what metric you want to use, L sub 2, L sub 0, L sub infinity, or any other.  The decision which metric to use is entirely outside the mathematics you use and should depend on your knowledge of the problem and the goals you have.  If the values you show are coming from a statistical sample (random variable) then the two gentlemen before me may have some good points to consider.

  • Brett Clark added an answer in Solid State Physics:
    Do you have the solutions of solid states by ashcraft?
    I want to khow the answers of the problems
    Brett Clark

    Would you mind sending me the solutions as well?


  • Jennifer Gibbons added an answer in Azocasein:
    Why azocasein unit is related to an increase of 0.01 OD ?

    Why one azocasein unit is defined as the amount of enzyme producing an increase of 0.01 OD ? Is it related to the extinction coefficient?

    I would like to understand the equation that my teacher gave in my lab protocol: 

    1 unit= DO (366 nm) / 0,01

    Jennifer Gibbons

    Enzyme units of measure are rather arbitrary- the answer is probably that was the way the activity was measured in the first publication about the enzyme. ;)

  • Ismael Mullor Ruiz asked a question in Metal Organic Frameworks:
    Given coordination conditions between a metal and a given ligand, which changes in such conditions favor the formation of Metal-Organic Frameworks?

    I currently have the coordination conditions for make Cu (II) and Zn (II) ions coordinate with a given tripeptide and I'm interested to make them coordinate forming an extended 3D crystalline framework

  • Ted Cole added an answer in Parkinson's Disease:
    What are the etiologic factors for Parkinson's disease and are there any preventive measures?

    I have observed 3 persons who had Parkinson's problem. One thing was common among them. All of them were versatile personalities i.e. multi-talented persons in their past life. Is there any correlation? If anybody can explain. 

    Ted Cole

    The primary cause of Parkinson's is toxin exposure with depletion of glutathione, followed by numerous other nutritional disruptions and subsequent damage to brain cells. Preventing Parkinson's is likely to happen if these factors are addressed before nutritional collapse occurs using amino acids as detailed in our latest papers. At this time we are able to obtain full remission of most Parkinson's symptoms following this approach.

  • Cameron Smart added an answer in Damage Mechanics:
    Can anyone provide some experimental phenomena where high damaged zones happen around macro cracks?

    Dear colleagues, could you provide me some experimental evidences (pictures) to show that high damaged zones often happen around the macro cracks?

    And does someone measure these damages (by a damage value), which are close to the macro cracks.

    I will be appreciate If you can give some references to me.

    Cameron Smart

    Is "damage zone" a new term? My theoretical knowledge goes back to Griffith's work on airplane parts 100 years ago (then glass specimens 90 years ago) and Irwin's ideas about crack tip plasticity 70 years ago. I have done experimental work on defects in pressure vessels using the "Folius Factor" method for predicting small leak or violent burst, but "damage zone" was not a phrase in use at the time. 

  • Jennifer Gibbons added an answer in Protein Purification:
    What happens if the Ni-NTA resin on my column runs dry?


    I am doing an affinity chromatography protein purification for a protein of interest. I made the error of leaving my pump on too long and my buffer solution ran dry and made my column run dry to the point where the top layer of my resin bed looked dried up, but the some of the bottom half was still hydrated.

    Have compromised my protein? What exactly happens when the resin runs dry?

    Jennifer Gibbons

    When the resin runs dry, air gets into the column. This prevents your protein from reaching the resin, or can prevent you from eluting the protein off of the resin. Ni-NTA is an affinity chromatography, so you can still save stuff- this next step wouldn't work with gel filtration and such. Stir your entire column into solution, and let settle. That should remove the air bubbles and you can move on with life. Now, as for any dried out protein, that depends on the protein.... ;)

  • Joseph Benoun asked a question in S2 Cells:
    Using S2 cells for tetramer induction using CuSO4, protein yield has been low, is it possible the stock CuSO4 (more than 2 yrs old) has gone bad?

    Making tetramer using S2 cells

    Induction is with copper sulfate 

    Protein yield should be higher than what it currently is according to protocols and other lab members who have made it previously

    Using previously made stock CuSO4 that has been on the shelf for a while

    Determined that protein is not being lost in the wash steps of purification.

  • John W Pickering added an answer in Power Analyses:
    Any advice on Post-hoc power analysis for ROC/AUC analyses?

    Hi all,

    I was wondering if anyone could help advise about any calculator or formula to retrospectively calculate the power of a study which uses ROC/AUC analyses? Unfortunately, of the information I have seen thus far the calculators are for a priori analyses.

    I understand some researchers advise against post hoc power analyses but I am interested in any calculators/formulas people may be aware of nonetheless

    Many thanks

    John W Pickering

    I guess you could go back to Hanley, J. A., & McNeil, B. J. (1982). The meaning and use of the area under a receiver operating characteristic (ROC) curve. Radiology, 143(1), 29–36. and create tables from which to read Power and alpha.  

    Having said that, I'm interested in why you would actually want to do this?  

    As an aside, something I've noted in ROC analysis in medicine is that rarely is a power calculation done a priori.  Furthermore, I suspect many of the studies I get to review are underpowered because of this.

  • Mohammad reza Khodaei added an answer in Tractography:
    What is the best program for HARDI diffusion data probabilistic tractography?

    I am working on human connectome HARDI diffusion data. In brief, the dataset has 1.25 mm isotropic voxels, 270 directions, 3  b-shells (1000,2000,3000) . I want to do seed-base probabilistic tractography. Since i am new to HARDI diffuison data tractography, which program is proper for my data?   Does MRtrix support multi shell data? which program support multi shell datas?

    Mohammad reza Khodaei

    Thanks a lot.

    And the last question, how long it takes to do probabilistic tractography for connectome single subject(1.25 mm isotropic voxels, 270 directions, 3 b-shells) ?

  • Ariel Linden added an answer in Troponin:
    What is an acceptable False Positive rate/Positive predictive value to rule-in AMI in the Emergency department?

    The European Society of Cardiology guidelines and strategies such as TRAPID AMI aim to stratify patients into low ("rule-out"), intermediate & high risk ("rule-in")  for AMI/ACS based on serial troponins, ECG, risk factors etc.  For obvious reasons a >99% sensitivity is the defacto standard for rule-out.  What then should be the specificity or ppv be? While ppv will vary according to prevalence, it matters to the cardiologists what proportion of patients they are told high risk actually have the disease.  I'd like input, especially from cardiologists, on what they think is an acceptable ppv rate and why?  Thanks.

    Ariel Linden

    Thank you! I will review this right now!

  • Servet Coskun asked a question in Unsupervised Learning:
    Trying to locate the algorithm/code for the paper Adaptive Road Following using Self-Supervised Learning and Reverse Optical Flow?

    In the paper I am not able to find a reference to their code, which isn't really a problem since the dissertation "UNSUPERVISED LEARNING AND REVERSE OPTICAL FLOW IN MOBILE ROBOTICS" p.68 is referring to the reader to the code for the same exact algorithm at the address http://cs.stanford.edu/group/lagr/road_following/

    Problem is that the link "only" includes 3 videos demoing the final algorithm. I'm interested in seeing and understanding the code but there's literally just 3 links to these videos.

    I hope some of you can help me find the code or point me in the right direction. So far I've managed to calculate the optical flow properly and I am now looking in to finding the starting horizontal position for the template matching.

    I hope it is OK to ask this question here, thank you.

  • Olga Lock added an answer in Plant Extracts:
    Does folin ciocalteu (phenolic content determination method) have reaction with flavonoids included in plant extract?

    when using folin ciocalteu method to determine phenolic content, does the result include flavonoid content in summation? 

    Olga Lock

    Yes, flavonoid compounds have reaction with Folin Ciocalteu reagent and it detected not only flavonoids but others phenolic compounds. 

  • Laura Kinnischtzke asked a question in Graphene:
    Connect graphene to electrode above or below flake?

    Hi -

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

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

  • Joaquim Mª Rius Bartra added an answer in Gaussian (Software):
    How can I optimize a Transition state structure in Gaussian 09 ?
    • Method: B3LYP/3-21g
    • Facing error in optimization after getting results of fixing atoms
    Joaquim Mª Rius Bartra

    Hello Hammad,

    Few days ago I prepared a guide about this type of calculation which could help you and there is explained different methodologies to obtain TS with gview and g09. 

    Also, if you do not found the answer inside the guide, feel free to contact me.

    I hope it helps you,

    Joaquim Rius

  • Emmanuel Ndashimye added an answer in OPNET:
    Any advice on creating a multi-interface wireless node in OPNET?

    I am working on vertical handoff in Heterogeneous wireless networks. I would like to create a mobile node with two or three network interface (Wi-Fi, LTE and WiMAX). however I don't have any idea how to do this! any help? you are welcome

    Emmanuel Ndashimye

    Thanks Rafaa. However , I am still looking for a help to do this in OPNET!

  • Ali Al‐Hisnawi added an answer in Aquaculture:
    Could you please tell about the free journals for publishing my manuscripts on field aquaculture

    aquaculture field and microbiota

    Ali Al‐Hisnawi

    Could you please tell me about the free journals for publishing my manuscripts on field aquaculture

  • Yuan-Yeu Yau added an answer in Agrobacterium:
    Why do my T3 seeds of the transgenic lines are not showing resistance to Hygromycin?

    We genetically transformed plants with a binary vector pCAMBIA carrying the DsRed gene, Hpt, and our gene of interest. The T1 and T2 seeds show red seed phenotype, and some of them were resistant to Hygromycin, considering that these two genes should be transferred together, as both will be part of the t-DNA insertion via agrobacterium. Why in some lines we got hygromycin resistance phenotype, and some lines we didn't; however, all are showing red seed phenotype under fluorescence. Please explain

    Yuan-Yeu Yau

    Hi Hesham,

    1. If you verify that you have a good single copy transgene, methylation-caused silencing can be used to explain it.

    2. Methylation can occur at different part of the T-DNA cassette. This has been reported (see below attached paper: Gene 2000). I also attached its Fig. 6 from the paper for you, and you can see different patterns of methylation along the transgene constructs occurred (attachment).

    + 1 more attachment

  • Mayadah Shehadeh added an answer in Extracts:
    What is the difference between the aqueous extract method and fraction extraction method?

    Is there is any maximum difference between these two extracts or difference may occur in component extraction.

    Mayadah Shehadeh

    You need to know that extraction is the use of a solvent whether it is organic e.g. methanol, chloroform, hexane, etc or just water or a combination of water and methanol to soak (macerate ) or even boil plant powder for a specified length of time. Once you separate plant material from the solvent by filtration or decantation, you get a liquid known as extract. 

    Using chromatography or liquid liquid fractionation procedure will produce fractions containing compounds with different affinity towards each solvent in use.

    hope this answer your question!!!