Assessing biogeochemical effects and best management practice for a wheat–maize cropping system using the DNDC model

Contemporary agriculture is shifting from a single-goal to a multi-goal strategy, which in turn requires choosing best management practice (BMP) based on an assessment of the biogeochemical effects of management alternatives. The bottleneck is the capacity of predicting the simultaneous effects of different management practice scenarios on multiple goals and choosing BMP among scenarios. The denitrification–decomposition (DNDC) model may provide an opportunity to solve this problem. We validated the DNDC model (version 95) using the observations of soil moisture and temperature, crop yields, aboveground biomass and fluxes of net ecosystem exchange of carbon dioxide, methane, nitrous oxide (N2O), nitric oxide (NO) and ammonia (NH3) from a wheat–maize cropping site in northern China. The model performed well for these variables. Then we used this model to simulate the effects of management practices on the goal variables of crop yields, NO emission, nitrate leaching, NH3 volatilization and net emission of greenhouse gases in the ecosystem (NEGE). Results showed that no-till and straw-incorporated practices had beneficial effects on crop yields and NEGE. Use of nitrification inhibitors decreased nitrate leaching and N2O and NO emissions, but they significantly increased NH3 volatilization. Irrigation based on crop demand significantly increased crop yield and decreased nitrate leaching and NH3 volatilization. Crop yields were hardly decreased if nitrogen dose was reduced by 15% or irrigation water amount was reduced by 25%. Two methods were used to identify BMP and resulted in the same BMP, which adopted the current crop cultivar, field operation schedules and full straw incorporation and applied nitrogen and irrigation water at 15 and 25% lower rates, respectively, than the current use. Our study indicates that the DNDC model can be used as a tool to assess biogeochemical effects of management alternatives and identify BMP

A Peculiar Flaring Episode of Cygnus X-1

Recent monitoring of Cyg X-1 with {\em RXTE} revealed a period of intense flaring, which started in October of 2000 and lasted until March of 2001. The source exhibited some quite unusual behaviors during this period. The soft X-ray flux of the source went up and down three times on a timescale of about one month, as discovered by the ASM aboard RXTE, before finally returning to the normal level (of the hard state). The observed spectral and temporal X-ray properties of Cyg X-1 are mostly intermediate between the canonical hard and soft states. This is known previously for strong X-ray flares, however, we show that the source did enter a period that resembles, in many ways, a sustained soft state during the last of the three flares. We make detailed comparisons between this flare and the 1996 state transition, in terms of the observed X-ray properties, such as flux--hardness correlation, X-ray spectrum, and power density spectrum. We point out the similarities and differences, and discuss possible implications of the results on our understanding of the phenomena of flares and state transitions associated with Cyg X-1.Comment: 4 pages, 3 figures, accepted for publication in ApJ Letter

Evolution of Iron Kα_{\alpha} Line Emission in the Black Hole Candidate GX 339-4

GX 339-4 was regularly monitored with RXTE during a period (in 1999) when its X-ray flux decreased significantly (from 4.2$\times 10^{-10}$ erg cm$^{-2} s^{-1}$ to 7.6$\times 10^{-12}$ erg cm$^{-2}$s$^{-1}$ in the 3--20 keV band), as the source settled into the ``off state''. Our spectral analysis revealed the presence of a prominent iron K$_{\alpha}$ line in the observed spectrum of the source for all observations. The line shows an interesting evolution: it is centered at $\sim$6.4 keV when the measured flux is above 5$\times 10^{-11}$ erg cm$^{-2} s^{-1}$, but is shifted to $\sim$6.7 keV at lower fluxes. The equivalent width of the line appears to increase significantly toward lower fluxes, although it is likely to be sensitive to calibration uncertainties. While the fluorescent emission of neutral or mildly ionized iron atoms in the accretion disk can perhaps account for the 6.4 keV line, as is often invoked for black hole candidates, it seems difficult to understand the 6.7 keV line with this mechanism, because the disk should be less ionized at lower fluxes (unless its density changes drastically). On the other hand, the 6.7 keV line might be due to recombination cascade of hydrogen or helium like iron ions in an optically thin, highly ionized plasma. We discuss the results in the context of proposed accretion models.Comment: 18 pages, 2 figures, accepted for publication in the ApJ in v552n2p May 10, 2001 issu

Baryonic Effect on chi_cJ Suppression in Au+Au Collisions at RHIC Energies

We predict that initially produced chi_cJ mesons at low transverse momentum in the central rapidity region are almost dissociated by nucleons and antinucleons in hadronic matter produced in central Au+Au collisions at RHIC energies sqrt {s_{NN}}= 130 and 200 GeV. In calculations the nucleon and antinucleon distributions in hadronic matter are results of evolution from their freeze-out distributions which well fit the experimental p_T spectra of proton and antiproton. Any measured chi_cJ mesons at low p_T are generated from deconfined matter and give an explicit proof of regeneration mechanism (recombination mechanism).Comment: 10 pages, 3 figures, Latex, a discussion added to the referenc

DCAF1 controls T-cell function via p53-dependent and -independent mechanisms

On activation, naive T cells grow in size and enter cell cycle to mount immune response. How the fundamental processes of T-cell growth and cell cycle entry are regulated is poorly understood. Here we report that DCAF1 (Ddb1–cullin4-associated-factor 1) is essential for these processes. The deletion of DCAF1 in T cells impairs their peripheral homeostasis. DCAF1 is upregulated on T-cell receptor activation and critical for activation-induced T-cell growth, cell cycle entry and proliferation. In addition, DCAF1 is required for T-cell expansion and function during anti-viral and autoimmune responses in vivo. DCAF1 deletion leads to a drastic stabilization of p53 protein, which can be attributed to a requirement of DCAF1 for MDM2-mediated p53 poly-ubiquitination. Importantly, p53 deletion rescues the cell cycle entry defect but not the growth defect of DCAF1-deficient cells. Therefore, DCAF1 is vital for T-cell function through p53-dependent and -independent mechanisms

Asymmetric Origin for Gravitino Relic Density in the Hybrid Gravity-Gauge Mediated Supersymmetry Breaking

We propose the hybrid gravity-gauge mediated supersymmetry breaking where the gravitino mass is about several GeV. The strong constraints on supersymmetry viable parameter space from the CMS and ATLAS experiments at the LHC can be relaxed due to the heavy colored supersymmetric particles, and it is consistent with null results in the dark matter (DM) direct search experiments such as XENON100. In particular, the possible maximal flavor and CP violations from the relatively small gravity mediation may naturally account for the recent LHCb anomaly. In addition, because the gravitino mass is around the asymmetric DM mass, we propose the asymmetric origin of the gravitino relic density and solve the cosmological coincident problem on the DM and baryon densities \Omega_{\rm DM}:\Omega_{B}\approx 5:1. The gravitino relic density arises from asymmetric metastable particle (AMP) late decay. However, we show that there is no AMP candidate in the minimal supersymmetric Standard Model (SM) due to the robust gaugino/Higgsino mediated wash-out effects. Interestingly, AMP can be realized in the well motivated supersymmetric SMs with vector-like particles or continuous U(1)_R symmetry. Especially, the lightest CP-even Higgs boson mass can be lifted in the supersymmetric SMs with vector-like particles.Comment: RevTex4, 21 pages, 1 figure, minor corrections, JHEP versio

Vegetarianismo adolescente como uma expressão da anorexia nervosa: Apresentação de uma proposta analítica

A anorexia nervosa é uma perturbação do comportamento alimentar cujos sintomas e etiologia se encontram ainda em discussão no âmbito da pesquisa psicológica e clínica (Waller, 1993). Alguns estudos (Bakan et al., 1993; Kadambari et al., 1986; O’Connor et al., 1987; Woodruff et al., 1994) assinalam que o vegetarianismo, uma escolha alimentar alternativa às dietas ortodoxas, ocorre em simultâneo com alguns casos de anorexia nervosa. Neste sentido, torna-se fundamental delinear neste artigo os sintomas e características demográficas que caracterizam estes dois comportamentos alimentares, de modo a ser posteriormente avaliada uma eventual relação entre estes. Complementarmente, uma perspectiva fenomenológica e sociocultural é aqui proposta no sentido de realçar alguns dos processos que clarificam a tríade mente/corpo/ sociedade expressa nestes ‘padrões alimentares’. Alguns argumentos breves são sugeridos num comentário final, de modo a serem introduzidas futuras linhas de investigação teóricas e empíricas.Anorexia nervosa is an eating disorder whose symptoms and aetiology are still being discussed within psychological and clinical research (Waller, 1993). Some studies (Bakan et al., 1993; Kadambari et al., 1986; O’Connor et al., 1987; Woodruff et al., 1994) assign that vegetarianism, an alternative eating choice to ortodox diets, occurs simultaneously to some cases of anorexia nervosa. In this sense, it is fundamental to map in this paper the symptoms and demographic features which caracterise these two eating behaviours, so that to further evaluate an eventual relationship between them. Complementary, a phenomenological and sociocultural perspective is here proposed so to highlight some of the processes which might clarify the mind/body/society triad expressed in these ‘food patterns’. Some brief arguments are suggested as a final comment, in order to introduce further lines of theoretical and empirical investigations. Keyinfo:eu-repo/semantics/publishedVersio

Gattini 2010: Cutting Edge Science at the Bottom of the World

The high altitude Antarctic sites of Dome A and the South Pole offer intriguing locations for future large scale optical astronomical Observatories. The Gattini project was created to measure the optical sky brightness, large area cloud cover and aurora of the winter-time sky above such high altitude Antarctic sites. The Gattini-DomeA camera was installed on the PLATO instrument module as part of the Chinese-led traverse to the highest point on the Antarctic plateau in January 2008. This single automated wide field camera contains a suite of Bessel photometric filters (B, V, R) and a long-pass red filter for the detection and monitoring of OH emission. We have in hand one complete winter-time dataset (2009) from the camera that was recently returned in April 2010. The Gattini-South Pole UV camera is a wide-field optical camera that in 2011 will measure for the first time the UV properties of the winter-time sky above the South Pole dark sector. This unique dataset will consist of frequent images taken in both broadband U and B filters in addition to high resolution (R similar to 5000) long slit spectroscopy over a narrow bandwidth of the central field. The camera is a proof of concept for the 2m-class Antarctic Cosmic Web Imager telescope, a dedicated experiment to directly detect and map the redshifted lyman alpha fluorescence or Cosmic Web emission we believe possible due to the unique geographical qualities of the site. We present the current status of both projects