3,770 research outputs found

    Productivity and Profitability of a Cotton-based Production System under Organic and Conventional Management in India

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    The debate on the relative benefits of conventional and organic farming systems is more topical than ever. The achievements of conventional high-input agriculture were largely brought about at the cost of deteriorating soil fertility; furthermore, they were based to a large extent on fossil fuels. Developing more sustainable farming practices on a large scale is of utmost importance. However, information about the performance of agricultural production systems under organic and conventional management in tropical and subtropical regions is largely lacking. This study aimed to assess agronomic and economic data from a long-term farming systems comparison trial under semi-arid conditions in central India. Four two-year crop rotations comprising cotton-soybean-wheat under biodynamic, organic and conventional management were investigated, including one conventional system with and one without transgenic Bt cotton, between 2007 and 2010. Results showed 13% lower yields in organic compared to conventional systems. Yields in cotton, soybean and wheat were on average 14 %, 7% and 15% lower, respectively. However, production costs of organic systems were on average 32% lower than those of conventional systems, which led to similar gross margins in all systems. To our knowledge, this is the first long-term field trial comparing the agronomic and economic performance of organic, conventional and conventional+Bt cotton-based farming systems. The results of our study suggest that organic farming is a promising alternative to conventional farming in cotton-based production systems in central India. The less capital intensive nature of organic systems may be particularly interesting for smallholder farmers as it decreases dependence on loans for farm inputs. Therefore, our findings have the potential to be useful for decision-making and in turn may lead to a redirection of agricultural policies

    Molecular Line Emission as a Tool for Galaxy Observations (LEGO). I. HCN as a tracer of moderate gas densities in molecular clouds and galaxies

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    Trends observed in galaxies, such as the Gao \& Solomon relation, suggest a linear relation between the star formation rate and the mass of dense gas available for star formation. Validation of such relations requires the establishment of reliable methods to trace the dense gas in galaxies. One frequent assumption is that the HCN (J=1J=1--0) transition is unambiguously associated with gas at H2\rm{}H_2 densities ≫104 cm−3\gg{}10^4~\rm{}cm^{-3}. If so, the mass of gas at densities ≫104 cm−3\gg{}10^4~\rm{}cm^{-3} could be inferred from the luminosity of this emission line, LHCN (1–0)L_{\rm{}HCN\,(1\text{--}0)}. Here we use observations of the Orion~A molecular cloud to show that the HCN (J=1J=1--0) line traces much lower densities ∼103 cm−3\sim{}10^3~\rm{}cm^{-3} in cold sections of this molecular cloud, corresponding to visual extinctions AV≈6 magA_V\approx{}6~\rm{}mag. We also find that cold and dense gas in a cloud like Orion produces too little HCN emission to explain LHCN (1–0)L_{\rm{}HCN\,(1\text{--}0)} in star--forming galaxies, suggesting that galaxies might contain a hitherto unknown source of HCN emission. In our sample of molecules observed at frequencies near 100~GHz (also including 12CO\rm{}^{12}CO, 13CO\rm{}^{13}CO, C18O\rm{}C^{18}O, CN, and CCH), N2H+\rm{}N_2H^+ is the only species clearly associated with rather dense gas.Comment: accepted to A&A Letter

    Sally Ride EarthKAM - Automated Image Geo-Referencing Using Google Earth Web Plug-In

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    Sally Ride EarthKAM is an educational program funded by NASA that aims to provide the public the ability to picture Earth from the perspective of the International Space Station (ISS). A computer-controlled camera is mounted on the ISS in a nadir-pointing window; however, timing limitations in the system cause inaccurate positional metadata. Manually correcting images within an orbit allows the positional metadata to be improved using mathematical regressions. The manual correction process is time-consuming and thus, unfeasible for a large number of images. The standard Google Earth program allows for the importing of KML (keyhole markup language) files that previously were created. These KML file-based overlays could then be manually manipulated as image overlays, saved, and then uploaded to the project server where they are parsed and the metadata in the database is updated. The new interface eliminates the need to save, download, open, re-save, and upload the KML files. Everything is processed on the Web, and all manipulations go directly into the database. Administrators also have the control to discard any single correction that was made and validate a correction. This program streamlines a process that previously required several critical steps and was probably too complex for the average user to complete successfully. The new process is theoretically simple enough for members of the public to make use of and contribute to the success of the Sally Ride EarthKAM project. Using the Google Earth Web plug-in, EarthKAM images, and associated metadata, this software allows users to interactively manipulate an EarthKAM image overlay, and update and improve the associated metadata. The Web interface uses the Google Earth JavaScript API along with PHP-PostgreSQL to present the user the same interface capabilities without leaving the Web. The simpler graphical user interface will allow the public to participate directly and meaningfully with EarthKAM. The use of similar techniques is being investigated to place ground-based observations in a Google Mars environment, allowing the MSL (Mars Science Laboratory) Science Team a means to visualize the rover and its environment

    \u3ci\u3eArgulus\u3c/i\u3e From the Pascagoula River, MS, USA, With an Emphasis On Those of the Threatened Gulf Sturgeon, \u3ci\u3eAcipenser oxyinchus desotoi\u3c/i\u3e

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    Species of Argulus (Branchiura Thorell, 1864) are common ectoparasites of freshwater, estuarine, and marine fishes. Argulid identification and taxonomy is often confusing because many species are reported to parasitize multiple host species, have similar morphological characters, and come from various salinity regimes. Gulf sturgeon is an anadromous fish natal to drainages in the north-central Gulf of Mexico, and as with many endangered species, has a poorly documented parasite community. During Gulf sturgeon tagging and monitoring studies (2016–2019) in the Pascagoula River, MS, USA, species of Argulus were collected from Gulf sturgeon as well as other incidentally captured fishes. Argulus flavescens Wilson, 1916 was found on Gulf sturgeon and flathead catfish, Argulus americanus Wilson, 1902 on bowfin, and Argulus bicolor Bere, 1936 on Atlantic stingray. We provide morphological details and measurements for these species as well as the first confirmed 28S rDNA molecular data. Argulus flavescens was more abundant and prevalent on larger Gulf sturgeon and on sturgeon captured in freshwater rather than estuarine habitats. Our results indicate that A. flacescens may not tolerate estuarine salinities and that the anadromous life-history pattern of Gulf sturgeon could help rid them of A. flavescens when they emigrate from their riverine habitats

    XVD Image Display Program

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    The XVD [X-Windows VICAR (video image communication and retrieval) Display] computer program offers an interactive display of VICAR and PDS (planetary data systems) images. It is designed to efficiently display multiple-GB images and runs on Solaris, Linux, or Mac OS X systems using X-Windows

    Infrared Emission from the Nearby Cool Core Cluster Abell 2597

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    We observed the brightest central galaxy (BCG) in the nearby (z=0.0821) cool core galaxy cluster Abell 2597 with the IRAC and MIPS instruments on board the Spitzer Space Telescope. The BCG was clearly detected in all Spitzer bandpasses, including the 70 and 160 micron wavebands. We report aperture photometry of the BCG. The spectral energy distribution exhibits a clear excess in the FIR over a Rayleigh-Jeans stellar tail, indicating a star formation rate of ~4-5 solar masses per year, consistent with the estimates from the UV and its H-alpha luminosity. This large FIR luminosity is consistent with that of a starburst or a Luminous Infrared Galaxy (LIRG), but together with a very massive and old population of stars that dominate the energy output of the galaxy. If the dust is at one temperature, the ratio of 70 to 160 micron fluxes indicate that the dust emitting mid-IR in this source is somewhat hotter than the dust emitting mid-IR in two BCGs at higher-redshift (z~0.2-0.3) and higher FIR luminosities observed earlier by Spitzer, in clusters Abell 1835 and Zwicky 3146.Comment: Accepted at Ap

    Nitrogen cost minimization is promoted by structural changes in the transcriptome of N-deprived Prochlorococcus cells

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    Prochlorococcus is a globally abundant marine cyanobacterium with many adaptations that reduce cellular nutrient requirements, facilitating growth in its nutrient-poor environment. One such genomic adaptation is the preferential utilization of amino acids containing fewer N-atoms, which minimizes cellular nitrogen requirements. We predicted that transcriptional regulation might further reduce cellular N budgets during transient N limitation. To explore this, we compared transcription start sites (TSSs) in Prochlorococcus MED4 under N-deprived and N-replete conditions. Of 64 genes with primary and internal TSSs in both conditions, N-deprived cells initiated transcription downstream of primary TSSs more frequently than N-replete cells. Additionally, 117 genes with only an internal TSS demonstrated increased internal transcription under N-deprivation. These shortened transcripts encode predicted proteins with an average of 21% less N content compared to full-length transcripts. We hypothesized that low translation rates, which afford greater control over protein abundances, would be beneficial to relatively slow-growing organisms like Prochlorococcus. Consistent with this idea, we found that Prochlorococcus exhibits greater usage of glycine-glycine motifs, which causes translational pausing, when compared to faster growing microbes. Our findings indicate that structural changes occur within the Prochlorococcus MED4 transcriptome during N-deprivation, potentially altering the size and structure of proteins expressed under nutrient limitation.Gordon and Betty Moore Foundation (Grant GBMF495)Simons Foundation (Award 329108)National Science Foundation (U.S.) (Grant DBI-0424599

    The TH1 cell lineage-determining transcription factor T-bet suppresses TH2 gene expression by redistributing GATA3 away from TH2 genes

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    Lineage-determining transcription factors (LD-TFs) drive the differentiation of progenitor cells into a specific lineage. In CD4+ T cells, T-bet dictates differentiation of the TH1 lineage, whereas GATA3 drives differentiation of the alternative TH2 lineage. However, LD-TFs, including T-bet and GATA3, are frequently co-expressed but how this affects LD-TF function is not known. By expressing T-bet and GATA3 separately or together in mouse T cells, we show that T-bet sequesters GATA3 at its target sites, thereby removing GATA3 from TH2 genes. This redistribution of GATA3 is independent of GATA3 DNA binding activity and is instead mediated by the T-bet DNA binding domain, which interacts with the GATA3 DNA binding domain and changes GATA3′s sequence binding preference. This mechanism allows T-bet to drive the TH1 gene expression program in the presence of GATA3. We propose that redistribution of one LD-TF by another may be a common mechanism that could explain how specific cell fate choices can be made even in the presence of other transcription factors driving alternative differentiation pathways

    Outbreak of Cutaneous Leishmaniasis in Peruvian Military Personnel Undertaking Training Activities in the Amazon Basin, 2010

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    ArticleMilitary personnel deployed to the Amazon Basin are at high risk for cutaneous leishmaniasis (CL). We responded to an outbreak among Peruvian Army personnel returning from short-term training in the Amazon, conducting active case detection, lesion sample collection, and risk factor assessment. The attack rate was 25% (76/303); the incubation period was 2–36 weeks (median = 8). Most cases had one lesion (66%), primarily ulcerative (49%), and in the legs (57%). Real-time polymerase chain reaction (PCR) identified Leishmania (Viannia) braziliensis (59/61 = 97%) and L. (V.) guyanensis (2/61 = 3%). Being male (risk ratio [RR] = 4.01; P = 0.034), not wearing long-sleeve clothes (RR = 1.71; P = 0.005), and sleeping in open rooms (RR = 1.80; P = 0.009) were associated with CL. Sodium stibogluconate therapy had a 41% cure rate, less than previously reported in Peru (70%; P < 0.001). After emphasizing pre-deployment education and other basic prevention measures, trainees in the following year had lower incidence (1/278 = 0.4%; P < 0.001). Basic prevention can reduce CL risk in deployed militaries.The outbreak response was supported by the Peruvian Army Health Command COSALE and the Peruvian Ministry of Health through the General Epidemiology Directorate and the Health Directorate II, south Lima, and the. In addition, partial support was provided by grants CO497_11_L1 and CO466_11_L1 of the Global Emerging Infections Surveillance and Response System (AFHSC/GEIS) of the U.S. Department of Defense and the training grant 2D43 TW007393 awarded to the U.S. Naval Medical Research Unit No. 6 (NAMRU-6) by the Fogarty International Center of the National Institutes of Health (FIC/NIH). This study is part of the dissertation of Marianela Ore for a Masters in Epidemiological Research offered jointly by the Universidad Peruana Cayetano Heredia (UPCH) and NAMRU-6
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