X-ray ionization of the intergalactic medium by quasars

We investigate the impact of quasars on the ionization of the surrounding intergalactic medium (IGM) with the radiative transfer code \texttt{CRASH4}, now accounting for X-rays and secondary electrons. After comparing with analytic solutions, we post-process a cosmic volume ($\approx 1.5\times 10^4$ Mpc$^3 h^{-3}$) containing a ULAS J1120+0641-like quasar (QSO) hosted by a $5 \times 10^{11} {\rm M}_\odot h^{-1}$ dark matter (DM) halo. We find that: (i) the average HII region ($R\sim3.2$~pMpc in a lifetime $t_f = 10^7$~yrs) is mainly set by UV flux, in agreement with semi-analytic scaling relations; (ii) a largely neutral ($x_{\textrm{HII}} < 0.001$), warm ($T\sim 10^3$~K) tail extends up to few Mpc beyond the ionization front, as a result of the X-ray flux; (iii) LyC-opaque inhomogeneities induce a line of sight (LOS) scatter in $R$ as high as few physical Mpc, consistent with the DLA scenario proposed to explain the anomalous size of the ULAS J1120+0641 ionized region. On the other hand, with an ionization rate $\dot{N}_{\gamma,0} \sim 10^{57}$~s$^{-1}$, the assumed DLA clustering and gas opacity, only one LOS shows an HII region compatible with the observed one. We deduce that either the ionization rate of the QSO is at least one order of magnitude lower or the ULAS J1120+0641 bright phase is shorter than $10^7$~yrs.Comment: Accepted for publication in MNRAS Main Journal, Accepted 2018 May 2

Field water dynamics in integrated systems in the Brazilian.

Agroforestry systems were established as a viable option for Brazilian farmers in recent decades. Shading is expected to affect the system?s microclimate and thus it is likely to alter water fluxes to the atmosphere via evapotranspiration. In this study we measured the evapotranspiration (ET) with micro-lysimeters in four different treatments as a proxy for different land use systems at EMBRAPA Beef Cattle, the Brazilian Agricultural Research Corporation, located in Campo Grande-MS, Brasil. The four treatments are: Integrated systems with rows of Eucalypt (Eucalyptus urograndis) trees (ICLF), integrated systems without Eucalypt trees (ICL), continuous pasture (CP) and native Cerrado (Savannah) vegetation. In the ICLF and ICL plots Bracchiaria brizantha was planted and in the CP plots Brachiaria decumbens. To measure the evapotranspiration lysimeters (diameter of 10 cm and a depth of 20 cm) were inserted into the ground and weighed daily during a period of 8 weeks. Within the ICLF systems, measurements were conducted in three different distances to the tree rows. In the treatments without trees the lysimeters were distributed randomly. Results were linked to data from the microclimate, i.e. wind speed, air humidity, and global radiation

The physical origins and dominant emission mechanisms of Lyman alpha haloes: Results from the TNG50 simulation in comparison to MUSE observations

Extended Lyman alpha emission is now commonly detected around high-redshift galaxies through stacking and even on individual basis. Despite recent observational advances, the physical origin of these Lyman alpha haloes (LAHs), as well as their relationships to galaxies, quasars, circumgalactic gas, and other environmental factors remains unclear. We present results from our new Lyman alpha full radiative transfer code voroiltis which runs directly on the unstructured Voronoi tessellation of cosmological hydrodynamical simulations. We make use of the TNG50 simulation and simulate LAHs from redshift z = 2 to z = 5, focusing on star-forming galaxies with 8.0 &lt; log10 (M∗ M⊙) &lt; 10.5. While TNG50 does not directly follow ionizing radiation, it includes an on-the-fly treatment for active galactic nuclei (AGNs) and ultraviolet background radiation with self-shielding, which are important processes impacting the cooling and ionization of the gas. Based on this model, we present the predictions for the stacked radial surface brightness profiles of Ly α as a function of galaxy mass and redshift. Comparison with data from the MUSE UDF at z &gt; 3 reveals a promising level of agreement. We measure the correlations of LAH size and central brightness with galaxy properties, finding that at the masses of 8.5 ≤ log10 (M∗/M⊙) ≤ 9.5, physical LAH sizes roughly double from z = 2 to z = 5. Finally, we decompose the profiles into contributions from diffuse emission and scattered photons from star-forming regions. In our simulations, we find rescattered photons from star-forming regions to be the major source in observed LAHs. Unexpectedly, we find that the flattening of LAH profiles at large radii becomes dominated by photons originating from other nearby haloes rather than diffuse emission itself

Brachiaria brizantha cv. BRS Piatã forage yield under integrated crop-livestock-forestry systems in Brazil.

Integrated crop-livestock-forestry (ICLF) systems are increasingly considered for a diversified agricultural production in Brazil. In this study we analysed the forage yield [kg DM ha?1], of Brachiaria brizantha BRS cv. Piat?a for ICLF demonstration plots at the Brazilian Agricultural Research Corporation - EMBRAPA, located in Campo Grande-MS, Brazil. The analysed plots with four replicates corresponded to three production systems: Two integrated crop-livestock-forestry systems (ICLF1 and ICLF2) and an integrated crop-livestock system (ICL). The trees (Eucalyptus urograndis) in the ICLF systems were planted in single rows with 2m between tress and 14 or 22m between rows, resulting in 357 trees ha?1 (ICLF1) and 277 trees ha?1 (ICLF2), respectively. The crop component is soy-bean, planted every 4 years. Grass biomass was sampled monthly in a line of five sampling points at equal distance from each other between tree rows to represent the understory shading gradient. Animal feed intake was considered using the moving cages method. During the dry season (June - October) the forage yields between the different treatments didn?t differ significantly from each other (average 5.4 kg DM ha?1). In the rainy season (November - January) the ICLF system had the highest forage yield (ICLF 17.7 > ICL 6.6 kg DM ha?1). Most likely the main reason for these results is due to the management practice. In the dry season the ICLF systems had such a low stocking rate compared to the ICL system, that in the rainy season the ICLF systems were able to exceed the forage production of the ICL system. In the tree plots during the dry season the forage yields along the shading gradient didn?t differ significantly (average 5.3 kg DM ha?1). In the rainy season the points with higher shading (near the tree rows) had lower forage yields (9.9 and 11.8 kg DM ha?1, respectively) than the central points (16.1 kg DM ha?1). The microclimate within the tree plots has a great effect on the forage production. During the dry season the shading effect of the trees on the whole area is more evenly distributed resulting in similar forage yields along the shading gradient

Dinâmica da água em sistemas de integração lavoura-pecuária-floresta.

Os sistemas de integração lavoura-pecuária-floresta (ILPF) oferecem opções promissoras de uso da terra para enfrentar os desafios previstos para sistemas de produção agrícola do futuro, mais especificamente a crescente demanda por produção de alimentos e uma gestão sustentável do uso da terra. No entanto, para se chegar a uma visão abrangente de como os sistemas de ILPF se comportam ecologicamente e em um contexto socioeconômico, precisamos de estudos de campo com análises aprofundadas. Um aspecto importante que até agora tem recebido pouca atenção, é a forma como os sistemas de uso da terra com ILPF afetam a dinâmica da água no solo. Preencher essa lacuna de conhecimento parece ambicioso, pois esses sistemas aparecem em múltiplas características, combinando diferentes componentes de lavouras, árvores, forrageiras e animais em diversos ambientes e sob gerenciamento que apresenta diversas variações. No entanto, para avançar na busca de opções de implementação dos sistemas de ILPF com intensificação sustentável, precisamos aumentar nosso conhecimento sobre como os recursos hídricos são afetados. Utilizando estudos de campo realizados em sistemas de ILPF estabelecidos em Campo Grande (MS), este capítulo aborda alguns desafios relacionados à análise da dinâmica da água em sistema de ILPF

Respostas fisiológicas e estruturais do capim-piatã sob níveis de sombreamento em sistemas de integração na época seca.

O capim-piatã (Brachiaria brizantha cv. BRS Piatã) destaca-se como uma das principais forrageiras cultivadas em sistemas de integração no Brasil, por seu valor nutritivo e adaptação em consórcio. Sistemas de integração lavoura-pecuária-floresta (ILPF) são apontados como importantes estratégias para sustentabilidade na produção agropecuária, e seu sucesso depende da tolerância da planta forrageira ao sombreamento

Contrasting CO2 and water vapour fluxes in dry forest and pasture sites of central Argentina

The dry forests of South America are a key player of the global carbon cycle and the regional water cycle, but they are being intensively deforested. We used eddy covariance measurements to compare the temporal patterns of CO2 and water vapour fluxes and their relationships with environmental variables in dry forest and pastures sites of central Argentina. Ecosystem fluxes showed clear contrasts in magnitude, timing and response to environmental controls between ecosystems. The dry forest displayed higher daily gross primary productivity (GPP, 10.6 vs. 7.8 g CO2 m−2 d−1) and ecosystem respiration (Reco, 9.1 vs. 7.0 g CO2 m−2 d−1) and lower net ecosystem exchange (NEE, −1.5 vs. −0.7 g CO2 m−2 d−1) than the pasture. These differences were explained by a lower tolerance of the pasture to cool temperatures and drought. The lowest NEE rates were observed between 26°C and 34°C in the pasture, but below this range, NEE increased sharply, switching to a carbon source with temperatures <20°C. By contrast, the dry forest remained as a strong carbon sink down to 18°C. The pasture also showed a stronger drop of GPP with drought compared with the dry forest, becoming a carbon source with soil wetness <25% of soil available water. Rainfall was strongly coupled with GPP in both ecosystems, but the dry forest responded to longer rainfall integration periods. This study helps to understand how ecosystems can respond to climate change, improve global scale modelling and increase the productivity and resilience of rangelands.Fil: Nosetto, Marcelo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Luna Toledo, Emanuel Santiago. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de Chilecito; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Magliano, Patricio Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Figuerola, Patricia Irene. Universidad Nacional de Chilecito; ArgentinaFil: Blanco, Lisandro Javier. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Jobbagy Gampel, Esteban Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; Argentin

Lipid Peroxidative Damage on Cisplatin Exposure and Alterations in Antioxidant Defense System in Rat Kidneys: A Possible Protective Effect of Selenium

Cisplatin (Cis-diamminedichloroplatinum II, CP) is an important chemotherapeutic agent, useful in the treatment of several cancers, but with several side effects such as nephrotoxicity. The present study investigated the possible protective effect of selenium (Se) against CP-induced oxidative stress in the rat kidneys. Male Wistar albino rats were injected with a single dose of cisplatin (7 mg CP/kg b.m., i.p.) and selenium (6 mg Se/kg b.m, as Na2SeO3, i.p.), alone or in combination. The obtained results showed that CP increased lipid peroxidation (LPO) and decreased reduced glutathione (GSH) concentrations, suggesting the CP-induced oxidative stress, while Se treatment reversed this change to control values. Acute intoxication of rats with CP was followed by statistically significant decreased activity of antioxidant defense enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and glutathione-S-transferase (GST). Treatment with Se reversed CP-induced alterations of antioxidant defense enzyme activities and significantly prevented the CP-induced kidney damage