121 research outputs found
Trocas gasosas e análises bioquímicas em variedades de melancia sob cultivo orgânico no Semiárido nordestino.
O objetivo deste trabalho foi avaliar numa escala temporal, os efeitos de doses de biofertilizante sobre as variáveis relacionadas às trocas gasosas e bioquímicas em três variedades de melancia cultivadas em sistema orgânico no semiárido nordestino. O experimento foi conduzido no campo experimental de Bebedouro (CEB) da EMBRAPA Semiárido em Petrolina-PE, com delineamento experimental em blocos casualizados, num esquema fatorial em parcela subsubdividida (3x6x3), contendo nas parcelas três variedades de melancia (Explorer; Red Heaven, e Majestic); nas subparcelas seis doses de biofertilizante (0; 80; 160; 240; 320 e 400 mL planta-1) e nas subsubparcelas três coletas ao longo do ciclo da cultura (30, 45 e 60 DAS), com quatro repetições. As doses intermediárias, entre 120 e 250 mL planta-1, dobiofertilizante proporcionaram os melhores valores de fotossíntese, condutância estomática, transpiração, açúcares solúveis totais e atividade da enzima redutase do nitrato nas variedades de melancia, com destaque para a variedade Explorer. As trocas gasosas e os parâmetros bioquímicos foram superiores na fase inicial e intermediaria do ciclo de cultivo, de 30 e 45 dias após semeadura. Palavras-chave: Citrillus lanatus, fisiologia vegetal, fotossíntese
The KELT Follow-Up Network And Transit False-Positive Catalog: Pre-Vetted False Positives For TESS
The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey of transiting planets orbiting bright stars for over 10 years. The KELT images have a pixel scale of ~23\u27\u27 pixel⁻¹—very similar to that of NASA\u27s Transiting Exoplanet Survey Satellite (TESS)—as well as a large point-spread function, and the KELT reduction pipeline uses a weighted photometric aperture with radius 3\u27. At this angular scale, multiple stars are typically blended in the photometric apertures. In order to identify false positives and confirm transiting exoplanets, we have assembled a follow-up network (KELT-FUN) to conduct imaging with spatial resolution, cadence, and photometric precision higher than the KELT telescopes, as well as spectroscopic observations of the candidate host stars. The KELT-FUN team has followed-up over 1600 planet candidates since 2011, resulting in more than 20 planet discoveries. Excluding ~450 false alarms of non-astrophysical origin (i.e., instrumental noise or systematics), we present an all-sky catalog of the 1128 bright stars (6 \u3c V \u3c 13) that show transit-like features in the KELT light curves, but which were subsequently determined to be astrophysical false positives (FPs) after photometric and/or spectroscopic follow-up observations. The KELT-FUN team continues to pursue KELT and other planet candidates and will eventually follow up certain classes of TESS candidates. The KELT FP catalog will help minimize the duplication of follow-up observations by current and future transit surveys such as TESS
Synthesis and Structure of Trinuclear W3S4 Clusters Bearing Aminophosphine Ligands and Their Reactivity toward Halides and Pseudohalides
The aminophosphine ligand (2-aminoethyl)- diphenylphosphine (edpp) has been coordinated to the W3(μ-
S)(μ-S)3 cluster unit to afford trimetallic complex [W3S4Br3(edpp)3]+ (1+) in a one-step synthesis process with high yields. Related [W3S4X3(edpp)3]+ clusters (X = F−, Cl−, NCS−; 2+−4+) have been isolated by treating 1+ with the
corresponding halide or pseudohalide salt. The structure of complexes 1+ to 4+ contains an incomplete W3S4 cubane-type cluster unit, and only one of the possible isomers is formed: the one with the phosphorus atoms trans to the capping sulfur and the amino groups trans to the bridging sulphurs. The remaining coordination position on each metal is occupied by X. Detailed studies using stopped-flow, 31P{1H} NMR, and ESI-MS have been carried out in order to understand the solution behavior and the kinetics of interconversion among species 1+, 2+, 3+, and 4+ in solution. Density functional theory (DFT) calculations have been also carried out on the reactions of cluster 1+ with the different anions. The whole set of experimental and theoretical data indicate that the actual mechanism of substitutions in these clusters is strongly dependent on the nature of the leaving and entering anions. The interaction between an entering F− and the amino group coordinated to the adjacent metal have also been found to be especially relevant to the kinetics of these reactions
Water-Soluble Mo3S4 Clusters Bearing Hydroxypropyl Diphosphine Ligands: Synthesis, Crystal Structure, Aqueous Speciation, and Kinetics of Substitution Reactions
The [Mo3S4Cl3(dhprpe)3]+ (1+) cluster cation has been prepared by reaction between Mo3S4Cl4(PPh3)3 (solvent)2 and the watersoluble 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe, L) ligand. The crystal structure of [1]2[Mo6Cl14] has been determined by X-ray diffraction methods and shows the typical incomplete cuboidal structure
with a capping and three bridging sulfides. The octahedral coordination around each metal center is completed with a chlorine and two phosphorus atoms of the diphosphine ligand. Depending on the pH, the hydroxo group of the functionalized diphosphine can substitute the chloride ligands and coordinate to the cluster core to give new clusters with tridentate deprotonated dhprpe ligands of formula [Mo3S4(dhprpe-H)3]+ (2+). A detailed study based on stopped-flow, 31P{1H} NMR, and electrospray ionization mass spectrometry techniques has been carried out to understand the behavior of acid−base equilibria and the kinetics of interconversion between the 1+ and the 2+ forms. Both conversion of 1+ to 2+ and its reverse process occur in a single kinetic step, so that reactions proceed at the three metal centers with statistically controlled kinetics. The values of the rate constants under different conditions are used to discuss on the mechanisms of opening and closing of the chelate rings with coordination or dissociation of chloride
Identification of novel risk loci, causal insights, and heritable risk for Parkinson's disease: a meta-analysis of genome-wide association studies
Background: Genome-wide association studies (GWAS) in Parkinson's disease have increased the scope of biological knowledge about the disease over the past decade. We aimed to use the largest aggregate of GWAS data to identify novel risk loci and gain further insight into the causes of Parkinson's disease. /
Methods: We did a meta-analysis of 17 datasets from Parkinson's disease GWAS available from European ancestry samples to nominate novel loci for disease risk. These datasets incorporated all available data. We then used these data to estimate heritable risk and develop predictive models of this heritability. We also used large gene expression and methylation resources to examine possible functional consequences as well as tissue, cell type, and biological pathway enrichments for the identified risk factors. Additionally, we examined shared genetic risk between Parkinson's disease and other phenotypes of interest via genetic correlations followed by Mendelian randomisation. /
Findings: Between Oct 1, 2017, and Aug 9, 2018, we analysed 7·8 million single nucleotide polymorphisms in 37 688 cases, 18 618 UK Biobank proxy-cases (ie, individuals who do not have Parkinson's disease but have a first degree relative that does), and 1·4 million controls. We identified 90 independent genome-wide significant risk signals across 78 genomic regions, including 38 novel independent risk signals in 37 loci. These 90 variants explained 16–36% of the heritable risk of Parkinson's disease depending on prevalence. Integrating methylation and expression data within a Mendelian randomisation framework identified putatively associated genes at 70 risk signals underlying GWAS loci for follow-up functional studies. Tissue-specific expression enrichment analyses suggested Parkinson's disease loci were heavily brain-enriched, with specific neuronal cell types being implicated from single cell data. We found significant genetic correlations with brain volumes (false discovery rate-adjusted p=0·0035 for intracranial volume, p=0·024 for putamen volume), smoking status (p=0·024), and educational attainment (p=0·038). Mendelian randomisation between cognitive performance and Parkinson's disease risk showed a robust association (p=8·00 × 10−7). /
Interpretation: These data provide the most comprehensive survey of genetic risk within Parkinson's disease to date, to the best of our knowledge, by revealing many additional Parkinson's disease risk loci, providing a biological context for these risk factors, and showing that a considerable genetic component of this disease remains unidentified. These associations derived from European ancestry datasets will need to be followed-up with more diverse data. /
Funding: The National Institute on Aging at the National Institutes of Health (USA), The Michael J Fox Foundation, and The Parkinson's Foundation (see appendix for full list of funding sources)
KELT-22Ab: A Massive, Short-Period Hot Jupiter Transiting A Near-Solar Twin
We present the discovery of KELT-22Ab, a hot Jupiter from the KELT-South survey. KELT-22Ab transits the moderately bright (V ~ 11.1) Sun-like G2V star TYC 7518-468-1. The planet has an orbital period of P = 1.3866529 ± 0.0000027 days, a radius of RP = 1.285 ((+0.12)/(=0.071)) RJ, and a relatively large mass of MP = 3.47 ((+0.15)/(=0.14)) MJ. The star has R★ = 1.099 ((+0.079)/(=0.046)) R⊙, M★ = 1.092 ((+0.045)/(-0.041) M⊙, Teff = 5767 ((+50)/(-49) K, log g★ = 4.393 ((+0.039)/(-0.060)) (cgs), and [m/H] = +0.259 ((+0.085)/(-0.083)); thus other than its slightly super-solar metallicity, it appears to be a near-solar twin. Surprisingly, KELT-22A exhibits kinematics and a Galactic orbit that are somewhat atypical for thin-disk stars. Nevertheless, the star is rotating rapidly for its estimated age, and shows evidence of chromospheric activity. Imaging reveals a slightly fainter companion to KELT-22A that is likely bound, with a projected separation of 6\u27\u27 (~1400 au). In addition to the orbital motion caused by the transiting planet, we detect a possible linear trend in the radial velocity of KELT-22A, suggesting the presence of another relatively nearby body that is perhaps non-stellar. KELT-22Ab is highly irradiated (as a consequence of the small semimajor axis of a/R★ = 4.97), and is mildly inflated. At such small separations, tidal forces become significant. The configuration of this system is optimal for measuring the rate of tidal dissipation within the host star. Our models predict that, due to tidal forces, the semimajor axis is decreasing rapidly, and KELT-22Ab is predicted to spiral into the star within the next Gyr
A process model of the formation of spatial presence experiences
In order to bridge interdisciplinary differences in Presence research and to establish connections between Presence and “older” concepts of psychology and communication, a theoretical model of the formation of Spatial Presence is proposed. It is applicable to the exposure to different media and intended to unify the existing efforts to develop a theory of Presence. The model includes assumptions about attention allocation, mental models, and involvement, and considers the role of media factors and user characteristics as well, thus incorporating much previous work. It is argued that a commonly accepted model of Spatial Presence is the only solution to secure further progress within the international, interdisciplinary and multiple-paradigm community of Presence research
A planet within the debris disk around the pre-main-sequence star AU Microscopii
AU Microscopii (AU Mic) is the second closest pre main sequence star, at a
distance of 9.79 parsecs and with an age of 22 million years. AU Mic possesses
a relatively rare and spatially resolved3 edge-on debris disk extending from
about 35 to 210 astronomical units from the star, and with clumps exhibiting
non-Keplerian motion. Detection of newly formed planets around such a star is
challenged by the presence of spots, plage, flares and other manifestations of
magnetic activity on the star. Here we report observations of a planet
transiting AU Mic. The transiting planet, AU Mic b, has an orbital period of
8.46 days, an orbital distance of 0.07 astronomical units, a radius of 0.4
Jupiter radii, and a mass of less than 0.18 Jupiter masses at 3 sigma
confidence. Our observations of a planet co-existing with a debris disk offer
the opportunity to test the predictions of current models of planet formation
and evolution.Comment: Nature, published June 24th [author spelling name fix
Identification of sixteen novel candidate genes for late onset Parkinson’s disease
Background
Parkinson’s disease (PD) is a neurodegenerative movement disorder affecting 1–5% of the general population for which neither effective cure nor early diagnostic tools are available that could tackle the pathology in the early phase. Here we report a multi-stage procedure to identify candidate genes likely involved in the etiopathogenesis of PD.
Methods
The study includes a discovery stage based on the analysis of whole exome data from 26 dominant late onset PD families, a validation analysis performed on 1542 independent PD patients and 706 controls from different cohorts and the assessment of polygenic variants load in the Italian cohort (394 unrelated patients and 203 controls).
Results
Family-based approach identified 28 disrupting variants in 26 candidate genes for PD including PARK2, PINK1, DJ-1(PARK7), LRRK2, HTRA2, FBXO7, EIF4G1, DNAJC6, DNAJC13, SNCAIP, AIMP2, CHMP1A, GIPC1, HMOX2, HSPA8, IMMT, KIF21B, KIF24, MAN2C1, RHOT2, SLC25A39, SPTBN1, TMEM175, TOMM22, TVP23A and ZSCAN21. Sixteen of them have not been associated to PD before, were expressed in mesencephalon and were involved in pathways potentially deregulated in PD. Mutation analysis in independent cohorts disclosed a significant excess of highly deleterious variants in cases (p = 0.0001), supporting their role in PD.
Moreover, we demonstrated that the co-inheritance of multiple rare variants (≥ 2) in the 26 genes may predict PD occurrence in about 20% of patients, both familial and sporadic cases, with high specificity (> 93%; p = 4.4 × 10− 5). Moreover, our data highlight the fact that the genetic landmarks of late onset PD does not systematically differ between sporadic and familial forms, especially in the case of small nuclear families and underline the importance of rare variants in the genetics of sporadic PD.
Furthermore, patients carrying multiple rare variants showed higher risk of manifesting dyskinesia induced by levodopa treatment.
Conclusions
Besides confirming the extreme genetic heterogeneity of PD, these data provide novel insights into the genetic of the disease and may be relevant for its prediction, diagnosis and treatment
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