2,282 research outputs found
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Viruses mobilize plant immunity to deter nonvector insect herbivores.
A parasite-infected host may promote performance of associated insect vectors; but possible parasite effects on nonvector insects have been largely unexplored. Here, we show that Begomovirus, the largest genus of plant viruses and transmitted exclusively by whitefly, reprogram plant immunity to promote the fitness of the vector and suppress performance of nonvector insects (i.e., cotton bollworm and aphid). Infected plants accumulated begomoviral βC1 proteins in the phloem where they were bound to the plant transcription factor WRKY20. This viral hijacking of WRKY20 spatiotemporally redeployed plant chemical immunity within the leaf and had the asymmetrical benefiting effects on the begomoviruses and its whitefly vectors while negatively affecting two nonvector competitors. This type of interaction between a parasite and two types of herbivores, i.e., vectors and nonvectors, occurs widely in various natural and agricultural ecosystems; thus, our results have broad implications for the ecological significance of parasite-vector-host tripartite interactions
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Semitransparent Perovskite Solar Cells with an Evaporated Ultra-Thin Perovskite Absorber
Metal halide perovskites are of great interest for application in semitransparent solar cells due to their tunable bandgap and high performance. However, fabricating high-efficiency perovskite semitransparent devices with high average visible transmittance (AVT) is challenging because of their high absorption coefficient. Here, a co-evaporation process is adopted to fabricate ultra-thin CsPbI3 perovskite films. The smooth surface and orientated crystal growth of the evaporated perovskite films make it possible to achieve 10 nm thin films with compact and continuous morphology without pinholes. When integrated into a p-i-n device structure of glass/ITO/PTAA/perovskite/PCBM/BCP/Al/Ag with an optimized transparent electrode, these ultra-thin layers result in an impressive open-circuit voltage (VOC) of 1.08 V and a fill factor (FF) of 80%. Consequently, a power conversion efficiency (PCE) of 3.6% with an AVT above 50% is demonstrated, which is the first report for a perovskite device of a 10 nm active layer thickness with high VOC, FF and AVT. These findings demonstrate that deposition by thermal evaporation makes it possible to form compact ultra-thin perovskite films, which are of great interest for future smart windows, light-emitting diodes, and tandem device applications
Effects of gastrointestinal motility on obesity
Background: Changes of gastrointestinal motility, which are important related to the food digestion and absorption in the gastrointestinal tract, may be one of the factors in obesity-formation. Aims The changes of gastrointestinal motility were explored in the rats from diet-induced obesity (DIO), diet-induced obese resistant (DR) or control (CON) by diet intervention. Methods: After fed with a high fat diet (HFD), 100 male Sprague–Dawley rats were divided into DIO, DR and CON groups. The rats from DIO and DR groups were fed with HFD, and CON with a basic diet (BD) for 6 weeks. Body weight, energy intake, gastric emptying, intestinal transit, motility of isolated small intestine segments and colon’s function were measured in this study. Expression of interstitial cells of Cajal (ICCs) and enteric nervous system (ENS) - choline acetyltransferase (ChAT), vasoactive intestinal peptides (VIP), substance P (SP) and NADPH-d histochemistry of nitric oxide synthase (NOS) were determined by immunohistochemistry. Results: Body weight and intake energy in the DIO group were higher than those in the DR group (p < 0.05). Gastric emptying of DIO group rats (78.33 ± 4.95%) was significantly faster than that of DR group (51.79 ± 10.72%) (p < 0.01). The peak value of motility in rat’s duodenum from the DR group was significantly higher than that in the DIO group (p < 0.05). In addition, the expression of interstitial cells of Cajal (ICC), choline acetyltransferase (ChAT), substance P (SP), vasoactive intestinal peptides (VIP) and neuronal nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) in the intestine of rats were significantly increased in the DIO group when compared to the DR group (p < 0.05). Conclusion: A faster gastric emptying, a weaker contraction of duodenum movement, and a stronger contraction and relaxation of ileum movement were found in the rats from the DIO group. It indicated that there has effect of gastrointestinal motility on obesity induced by HFD
The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7
We present the discovery of nine quasars at identified in the Sloan
Digital Sky Survey (SDSS) imaging data. This completes our survey of
quasars in the SDSS footprint. Our final sample consists of 52 quasars at
, including 29 quasars with mag selected from
11,240 deg of the SDSS single-epoch imaging survey (the main survey), 10
quasars with selected from 4223 deg of the SDSS
overlap regions (regions with two or more imaging scans), and 13 quasars down
to mag from the 277 deg in Stripe 82. They span a
wide luminosity range of . This well-defined sample
is used to derive the quasar luminosity function (QLF) at . After
combining our SDSS sample with two faint ( mag) quasars from
the literature, we obtain the parameters for a double power-law fit to the QLF.
The bright-end slope of the QLF is well constrained to be
. Due to the small number of low-luminosity quasars, the
faint-end slope and the characteristic magnitude are
less well constrained, with and
mag. The spatial density of luminous quasars,
parametrized as , drops rapidly
from to 6, with . Based on our fitted QLF and assuming
an IGM clumping factor of , we find that the observed quasar population
cannot provide enough photons to ionize the IGM at \%
confidence. Quasars may still provide a significant fraction of the required
photons, although much larger samples of faint quasars are needed for more
stringent constraints on the quasar contribution to reionization.Comment: 20 pages, 12 figures, Accepted for publication in The Astrophysical
Journa
Group-level safety climate in the construction industry: Influence of organizational, group, and individual factors
Group-level safety climate (GSC) is a recognized leading indicator of safety performance in the literature. However, there is limited understanding of the mechanisms through which multilevel (i.e., organizational, group, and individual) factors collectively influence GSC as promoted by general contractors in construction. A model is proposed to examine the interactions and causal relationships between four multilevel factors - organizational-level safety climate (OSC), coworker support (CS), supervisory safety-specific transformational leadership (SSTL), individual psychological capital (PsyCap) - and GSC. A two-wave online survey was conducted within a large contractor company in the US over 2 years. A total of 280 employees completed both surveys. The structural equation modeling analysis technique was adopted to test the hypotheses. The results show that OSC, CS, and supervisory SSTL significantly contribute to GSC. In addition, supervisory SSTL and CS positively affect individual PsyCap, and PsyCap positively moderates the relationship between supervisory SSTL and GSC. The study suggests that construction contractors should consider implementing leadership and PsyCap interventions to cultivate a positive GSC that potentially can lead to improved safety performance
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