1,508,160 research outputs found

    Soil structure and earthworm activity under different tillage systems in organic farming

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    Organic farmers are encouraged to adopt conservation tillage to preserve soil quality and fertility and prevent erosion. However, many studies in different soil and climate conditions have demonstrated that the compaction of the untilled layer is higher in conservation tillage than in conventional tillage. As earthworm activity may help alleviate soil compaction in organic farming, the impact on the soil structure and earthworm population and activity was studied for 4 different tillage managements (1) mouldboard ploughing (MP), (2) shallow ploughing (SP), (3) reduced tillage (RT) and (4) no-tillage (NT), in 3 french areas. The first results are: (1) MP soil structure is better than SP, RT and NT, (2) water infiltration is higher at soil surface in SP, RT and NT, lower at 17 cm depth, (3) more earthworms, especially anecic species, are found in NT, (4) but more opening channels are found in MP. Then, during the first years of transition from MP to NT, soil structure is better in MP, and whereas earthworm numbers is reduced, it favours earthworm activity

    Microbial protein out of thin air : fixation of nitrogen gas by an autotrophic hydrogen-oxidizing bacterial enrichment

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    For the production of edible microbial protein (MP), ammonia generated by the Haber-Bosch process or reclaimed ammonia from waste streams is typically considered as the nitrogen source. These processes for ammonia production are highly energy intensive. In this study, the potential for using nitrogen gas (N-2) as a direct nitrogen source for MP production by hydrogen-oxidizing bacteria (HOB) was evaluated. The use of N-2 versus ammonium as nitrogen source during the enrichment process resulted in differentiation of the bacterial community composition of the enrichments. A few previously unknown potential N-2-fixing HOB taxa (i.e., representatives of the genus Azonexus and the family Comamonadaceae) dominated the enrichments. The biomass yield of a N-2-fixing HOB enrichment was 30-50% lower than that of the ammonium-based HOB enrichment from the same inoculum source. The dried biomass of N-2-fixing HOB had a high protein content (62.0 +/- 6.3%) and an essential amino acid profile comparable to MP from ammonium-based HOB. MP from N-2-fixing HOB could potentially be produced in situ without entailing the emissions caused by ammonia production and transportation by conventional means. It could be a promising substitute for N-2-fixing protein-rich soybean because it has 70% higher protein content and double energy conversion efficiency from solar energy to biomass

    Attenuation of ischemic liver injury by prostaglandin E<inf>1</inf> analogue, misoprostol, and prostaglandin I<inf>2</inf> analogue, OP-41483

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    Background: Prostaglandin has been reported to have protective effects against liver injury. Use of this agent in clinical settings, however, is limited because of drugrelated side effects. This study investigated whether misoprostol, prostaglandin E1 analogue, and OP-41483, prostaglandin I2 analogue, which have fewer adverse effects with a longer half-life, attenuate ischemic liver damage. Study Design: Thirty beagle dogs underwent 2 hours of hepatic vascular exclusion using venovenous bypass. Misoprostol was administered intravenously for 30 minutes before ischemia and for 3 hours after reperfusion. OP-41483 was administered intraportally for 30 minutes before ischemia (2 μg/kg/min) and for 3 hours after reperfusion (0.5 μg/kg/min). Animals were divided into five groups: untreated control group (n = 10); high-dose misoprostol (total 100 μg/kg) group (MP-H, n = 5); middle-dose misoprostol (50 μg/kg) group (MP-M, n = 5); low-dose misoprostol (25 μg/kg) group (MP-L, n = 5); and OP-41483 group (OP, n = 5). Animal survival, hepatic tissue blood flow (HTBF), liver function, and histology were analyzed. Results: Two-week animal survival rates were 30% in control, 60% in MP-H, 100% in MP-M, 80% in MP-L, and 100% in OP. The treatments with prostaglandin analogues improved HTBF, and attenuated liver enzyme release, adenine nucleotrides degradation, and histologic abnormalities. In contrast to the MP-H animals that exhibited unstable cardiovascular systems, the MP- M, MP-L, and OP animals experienced only transient hypotension. Conclusions: These results indicate that misoprostol and OP-41483 prevent ischemic liver damage, although careful dose adjustment of misoprostol is required to obtain the best protection with minimal side effects

    Confirmation of a charged charmoniumlike state Zc(3885)Z_c(3885)^{\mp} in e+eπ±(DDˉ)e^+e^-\to\pi^{\pm}(D\bar{D}^*)^\mp with double DD tag

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    We present a study of the process e+eπ±(DDˉ)e^+e^-\to\pi^{\pm}(D\bar{D}^*)^{\mp} using data samples of 1092~pb1^{-1} at s=4.23\sqrt{s}=4.23~GeV and 826~pb1^{-1} at s=4.26\sqrt{s}=4.26~GeV collected with the BESIII detector at the BEPCII storage ring. With full reconstruction of the DD meson pair and the bachelor π±\pi^{\pm} in the final state, we confirm the existence of the charged structure Zc(3885)Z_c(3885)^{\mp} in the (DDˉ)(D\bar{D}^*)^{\mp} system in the two isospin processes e+eπ+D0De^+e^-\to\pi^+D^0D^{*-} and e+eπ+DD0e^+e^-\to\pi^+D^-D^{*0}. By performing a simultaneous fit, the statistical significance of Zc(3885)Zc(3885)^{\mp} signal is determined to be greater than 10σ\sigma, and its pole mass and width are measured to be MpoleM_{\rm{pole}}=(3881.7±\pm1.6(stat.)±\pm1.6(syst.))~MeV/c2c^2 and Γpole\Gamma_{\rm{pole}}=(26.6±\pm2.0(stat.)±\pm2.1(syst.))~MeV, respectively. The Born cross section times the (DDˉ)(D\bar{D}^*)^{\mp} branching fraction (σ(e+eπ±Zc(3885))×Br(Zc(3885)(DDˉ))\sigma(e^+e^-\to\pi^{\pm}Z_{c}(3885)^{\mp}) \times Br(Z_{c}(3885)^{\mp}\to(D\bar{D}^*)^{\mp})) is measured to be (141.6±7.9(stat.)±12.3(syst.)) pb(141.6\pm7.9(\text{stat.})\pm12.3(\text{syst.}))~\text{pb} at s=4.23\sqrt{s}=4.23~GeV and (108.4±6.9(stat.)±8.8(syst.)) pb(108.4\pm6.9(\text{stat.})\pm8.8(\text{syst.}))~\text{pb} at s=4.26\sqrt{s}=4.26~GeV. The polar angular distribution of the π±\pi^{\pm}-Zc(3885)Z_c(3885)^{\mp} system is consistent with the expectation of a quantum number assignment of JP=1+J^P=1^+ for Zc(3885)Z_c(3885)^{\mp}

    A performance comparison of the Cray-2 and the Cray X-MP

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    A suite of thirteen large Fortran benchmark codes were run on Cray-2 and Cray X-MP supercomputers. These codes were a mix of compute-intensive scientific application programs (mostly Computational Fluid Dynamics) and some special vectorized computation exercise programs. For the general class of programs tested on the Cray-2, most of which were not specially tuned for speed, the floating point operation rates varied under a variety of system load configurations from 40 percent up to 125 percent of X-MP performance rates. It is concluded that the Cray-2, in the original system configuration studied (without memory pseudo-banking) will run untuned Fortran code, on average, about 70 percent of X-MP speeds

    XO-5b: A Transiting Jupiter-sized Planet With A Four Day Period

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    The star XO-5 (GSC 02959-00729, V=12.1, G8V) hosts a Jupiter-sized, Rp=1.15+/-0.12 Rjup, transiting extrasolar planet, XO-5b, with an orbital period of P=4.187732+/-0.00002 days. The planet mass (Mp=1.15+/-0.08 Mjup) and surface gravity (gp=22+/-5 m/s^2) are significantly larger than expected by empirical Mp-P and Mp-P-[Fe/H] relationships. However, the deviation from the Mp-P relationship for XO-5b is not large enough to suggest a distinct type of planet as is suggested for GJ 436b, HAT-P-2b, and XO-3b. By coincidence XO-5 overlies the extreme H I plume that emanates from the interacting galaxy pair NGC 2444/NGC 2445 (Arp 143).Comment: 10 pages, 9 Figures, Submitted to Ap
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