271 research outputs found
The insights from theoretical calculation on the photophysical properties of a series of phosphorescent iridium(III) complexes
816-820The electronic structure and photophysical properties of three Ir(III) complexes with the substituted 5,5′-di(trifluoromethyl)-3,3′-bipyrazole(bipz) ligand have been theoretically investigated by using density functional theory and time-dependent density functional theory method. The calculated results show that the energy gaps between of LUMO and HOMO (ΔEL→H) of complexes 1, 2 and 3 are gradually decreased, that is, 3.54 eV, 3.07 eV and 2.95 eV for 1, 2 and 3, respectively. The lowest energy absorption wavelength of 1, 2 and 3 are located at 443 nm, 532 nm and 564 nm, respectively. The calculated 443 nm absorption for 1 is in good agreement with the experimental value. The lowest energy emissions of complexes 1, 2 and 3 are localized at 545 nm, 679 nm and 731 nm, respectively, simulated in CH2Cl2 medium at TPSSH level. The conclusion can be drawn that the different substituent groups in the bipz ligand results in the important effect on the electronic structure and photophysical properties. The research work can provide valuable information for the design of new organic light-emitting diodes materials
Illuminating Hot Jupiters in caustic crossing
In recent years a large number of Hot Jupiters orbiting in a very close orbit
around the parent stars have been explored with the transit and doppler effect
methods. Here in this work we study the gravitational microlensing effect of a
binary lens on a parent star with a Hot Jupiter revolving around it. Caustic
crossing of the planet makes enhancements on the light curve of the parent star
in which the signature of the planet can be detected by high precision
photometric observations. We use the inverse ray shooting method with tree code
algorithm to generate the combined light curve of the parent star and the
planet. In order to investigate the probability of observing the planet signal,
we do a Monte-Carlo simulation and obtain the observational optical depth of
. We show that about ten years observations of Galactic
Bulge with a network of telescopes will enable us detecting about ten Hot
Jupiter with this method. Finally we show that the observation of the
microlensing event in infra-red band will increase the probability for
detection of the exo-planets.Comment: 8 pages, 7 figures, accepted in MNRA
Plug-and-Play Knowledge Injection for Pre-trained Language Models
Injecting external knowledge can improve the performance of pre-trained
language models (PLMs) on various downstream NLP tasks. However, massive
retraining is required to deploy new knowledge injection methods or knowledge
bases for downstream tasks. In this work, we are the first to study how to
improve the flexibility and efficiency of knowledge injection by reusing
existing downstream models. To this end, we explore a new paradigm
plug-and-play knowledge injection, where knowledge bases are injected into
frozen existing downstream models by a knowledge plugin. Correspondingly, we
propose a plug-and-play injection method map-tuning, which trains a mapping of
knowledge embeddings to enrich model inputs with mapped embeddings while
keeping model parameters frozen. Experimental results on three knowledge-driven
NLP tasks show that existing injection methods are not suitable for the new
paradigm, while map-tuning effectively improves the performance of downstream
models. Moreover, we show that a frozen downstream model can be well adapted to
different domains with different mapping networks of domain knowledge. Our code
and models are available at https://github.com/THUNLP/Knowledge-Plugin.Comment: ACL 202
Chemokine-driven lymphocyte infiltration: an early intratumoural event determining long-term survival in resectable hepatocellular carcinoma
Objective Hepatocellular carcinoma (HCC) is a heterogeneous disease with poor prognosis and limited methods for predicting patient survival. The nature of the immune cells that infiltrate tumours is known to impact clinical outcome. However, the molecular events that regulate this infiltration require further understanding. Here the ability of immune genes expressed in the tumour microenvironment to predict disease progression was investigated.MethodsUsing quantitative PCR, the expression of 14 immune genes in resected tumour tissues from 57 Singaporean patients was analysed. The nearest-template prediction method was used to derive and test a prognostic signature from this training cohort. The signature was then validated in an independent cohort of 98 patients from Hong Kong and Zurich. Intratumoural components expressing these critical immune genes were identified by in situ labelling. Regulation of these genes was analysed in vitro using the HCC cell line SNU-182.ResultsThe identified 14 immune-gene signature predicts patient survival in both the training cohort (p=0.0004 and HR=5.2) and the validation cohort (p=0.0051 and HR=2.5) irrespective of patient ethnicity and disease aetiology. Importantly, it predicts the survival of patients with early disease (stages I and II), for whom classical clinical parameters provide limited information. The lack of predictive power in late disease stages III and IV emphasises that a protective immune microenvironment has to be established early in order to impact disease progression significantly. This signature includes the chemokine genes CXCL10, CCL5 and CCL2, whose expression correlates with markers of T helper 1 (Th1), CD8(+) T and natural killer (NK) cells. Inflammatory cytokines (tumour necrosis factor α, interferon γ) and Toll-like receptor 3 ligands stimulate intratumoural production of these chemokines which drive tumour infiltration by T and NK cells, leading to enhanced cancer cell death.ConclusionA 14 immune-gene signature, which identifies molecular cues driving tumour infiltration by lymphocytes, accurately predicts survival of patients with HCC especially in early disease
Semiparametric maximum likelihood inference for nonignorable nonresponse with callbacks
Ministry of Education, Singapore under its Academic Research Funding Tier
SPECULOOS exoplanet search and its prototype on TRAPPIST
One of the most significant goals of modern science is establishing whether
life exists around other suns. The most direct path towards its achievement is
the detection and atmospheric characterization of terrestrial exoplanets with
potentially habitable surface conditions. The nearest ultracool dwarfs (UCDs),
i.e. very-low-mass stars and brown dwarfs with effective temperatures lower
than 2700 K, represent a unique opportunity to reach this goal within the next
decade. The potential of the transit method for detecting potentially habitable
Earth-sized planets around these objects is drastically increased compared to
Earth-Sun analogs. Furthermore, only a terrestrial planet transiting a nearby
UCD would be amenable for a thorough atmospheric characterization, including
the search for possible biosignatures, with near-future facilities such as the
James Webb Space Telescope. In this chapter, we first describe the physical
properties of UCDs as well as the unique potential they offer for the detection
of potentially habitable Earth-sized planets suitable for atmospheric
characterization. Then, we present the SPECULOOS ground-based transit survey,
that will search for Earth-sized planets transiting the nearest UCDs, as well
as its prototype survey on the TRAPPIST telescopes. We conclude by discussing
the prospects offered by the recent detection by this prototype survey of a
system of seven temperate Earth-sized planets transiting a nearby UCD,
TRAPPIST-1.Comment: Submitted as a chapter in the "Handbook of Exoplanets" (editors: H.
Deeg & J.A. Belmonte; Section Editor: N. Narita). 16 pages, 4 figure
Effects of excluding grazing on the vegetation and soils of degraded sparse-elm grassland in the Horqin Sandy Land, China
Livestock grazing is a crucial cause of vegetation degradation and desertification in sandy lands. The sparse-elm grassland of Horqin Sandy Land, China has suffered severe degradation of biodiversity and ecosystem services. Management to exclude grazing is often necessary for ecological restoration, especially in arid and semi-arid regions. We report effects on vegetation and soils in a 10-year experiment to exclude livestock, completely or seasonally, in comparison with a continuously grazed area in Horqin. Complete exclusion of grazing and restriction of grazing to summer both led to significantly increased plant cover and density relative to the grazed control. Species richness increased, reflected in higher Shannon-Wiener indices; only complete exclusion increased the Simpson diversity index, whereas Pielou evenness was significantly lowest under seasonal grazing. Exclosure treatments were also associated with improved soil texture, and increased water retention, available nitrogen, total nitrogen, total carbon and total phosphorus. Soil pH and C/N ratio were highest under the seasonal grazing regime. The results indicated that exclosure management indeed improved biodiversity and ecosystem services in an erosion-prone region. Although total exclosure was most effective in restoration of degraded sparse-elm grassland, seasonal grazing management was highly beneficial and represented a good compromise with resource utilization and economic development
Vaccine Efficacy in Senescent Mice Challenged with Recombinant SARS-CoV Bearing Epidemic and Zoonotic Spike Variants
BACKGROUND: In 2003, severe acute respiratory syndrome coronavirus (SARS-CoV) was identified as the etiological agent of severe acute respiratory syndrome, a disease characterized by severe pneumonia that sometimes results in death. SARS-CoV is a zoonotic virus that crossed the species barrier, most likely originating from bats or from other species including civets, raccoon dogs, domestic cats, swine, and rodents. A SARS-CoV vaccine should confer long-term protection, especially in vulnerable senescent populations, against both the 2003 epidemic strains and zoonotic strains that may yet emerge from animal reservoirs. We report the comprehensive investigation of SARS vaccine efficacy in young and senescent mice following homologous and heterologous challenge. METHODS AND FINDINGS: Using Venezuelan equine encephalitis virus replicon particles (VRP) expressing the 2003 epidemic Urbani SARS-CoV strain spike (S) glycoprotein (VRP-S) or the nucleocapsid (N) protein from the same strain (VRP-N), we demonstrate that VRP-S, but not VRP-N vaccines provide complete short- and long-term protection against homologous strain challenge in young and senescent mice. To test VRP vaccine efficacy against a heterologous SARS-CoV, we used phylogenetic analyses, synthetic biology, and reverse genetics to construct a chimeric virus (icGDO3-S) encoding a synthetic S glycoprotein gene of the most genetically divergent human strain, GDO3, which clusters among the zoonotic SARS-CoV. icGD03-S replicated efficiently in human airway epithelial cells and in the lungs of young and senescent mice, and was highly resistant to neutralization with antisera directed against the Urbani strain. Although VRP-S vaccines provided complete short-term protection against heterologous icGD03-S challenge in young mice, only limited protection was seen in vaccinated senescent animals. VRP-N vaccines not only failed to protect from homologous or heterologous challenge, but resulted in enhanced immunopathology with eosinophilic infiltrates within the lungs of SARS-CoV–challenged mice. VRP-N–induced pathology presented at day 4, peaked around day 7, and persisted through day 14, and was likely mediated by cellular immune responses. CONCLUSIONS: This study identifies gaps and challenges in vaccine design for controlling future SARS-CoV zoonosis, especially in vulnerable elderly populations. The availability of a SARS-CoV virus bearing heterologous S glycoproteins provides a robust challenge inoculum for evaluating vaccine efficacy against zoonotic strains, the most likely source of future outbreaks
Genome-wide association studies in women of African ancestry identified 3q26.21 as a novel susceptibility locus for oestrogen receptor negative breast cancer
Multiple breast cancer loci have been identified in previous genome-wide association studies, but they were mainly conducted in populations of European ancestry. Women of African ancestry are more likely to have young-onset and oestrogen receptor (ER) negative breast cancer for reasons that are unknown and understudied. To identify genetic risk factors for breast cancer in women of African descent, we conducted a meta-analysis of two genome-wide association studies of breast cancer; one study consists of 1,657 cases and 2,029 controls genotyped with Illumina's HumanOmni2.5 BeadChip and the other study included 3,016 cases and 2,745 controls genotyped using Illumina Human1M-Duo BeadChip. The top 18,376 single nucleotide polymorphisms (SNP) from the meta-analysis were replicated in the third study that consists of 1,984 African Americans cases and 2,939 controls. We found that SNP rs13074711, 26.5 Kb upstream of TNFSF10 at 3q26.21, was significantly associated with risk of oestrogen receptor (ER)-negative breast cancer (odds ratio [OR]=1.29, 95% CI: 1.18-1.40; P = 1.8 × 10 (-) (8)). Functional annotations suggest that the TNFSF10 gene may be involved in breast cancer aetiology, but further functional experiments are needed. In addition, we confirmed SNP rs10069690 was the best indicator for ER-negative breast cancer at 5p15.33 (OR = 1.30; P = 2.4 × 10 (-) (10)) and identified rs12998806 as the best indicator for ER-positive breast cancer at 2q35 (OR = 1.34; P = 2.2 × 10 (-) (8)) for women of African ancestry. These findings demonstrated additional susceptibility alleles for breast cancer can be revealed in diverse populations and have important public health implications in building race/ethnicity-specific risk prediction model for breast cancer
- …