3,211 research outputs found
Prevalence of internet addiction disorder in Chinese university students: A comprehensive meta-analysis of observational studies
Background and aims: Internet addiction disorder (IAD) is common in university students. A number of studies have examined the prevalence of IAD in Chinese university students, but the results have been inconsistent. This is a meta-analysis of the prevalence of IAD and its associated factors in Chinese university students.
Methods: Both English (PubMed, PsycINFO, and Embase) and Chinese (Wan Fang Database and Chinese National Knowledge Infrastructure) databases were systematically and independently searched from their inception until January 16, 2017.
Results: Altogether 70 studies covering 122,454 university students were included in the meta-analysis. Using the random-effects model, the pooled overall prevalence of IAD was 11.3% (95% CI: 10.1%–12.5%). When using the 8-item Young Diagnostic Questionnaire, the 10-item modified Young Diagnostic Questionnaire, the 20-item Internet Addiction Test, and the 26-item Chen Internet Addiction Scale, the pooled prevalence of IAD was 8.4% (95% CI: 6.7%–10.4%), 9.3% (95% CI: 7.6%–11.4%), 11.2% (95% CI: 8.8%–14.3%), and 14.0% (95% CI: 10.6%–18.4%), respectively. Subgroup analyses revealed that the pooled prevalence of IAD was significantly associated with the measurement instrument (Q = 9.41, p = .024). Male gender, higher grade, and urban abode were also significantly associated with IAD. The prevalence of IAD was also higher in eastern and central of China than in its northern and western regions (10.7% vs. 8.1%, Q = 4.90, p = .027).
Conclusions: IAD is common among Chinese university students. Appropriate strategies for the prevention and treatment of IAD in this population need greater attention
浅谈护士长非权力影响力与护理人员工作投入水平的关系
Objective: To explore the effects of the headnurses’ non-power influenceon the nurses’ work engagement. Methods: To conduct a questionnaire survey on 450 nurses of the clinical nursing units of The Peoples' Hospital of Jilin Province.Results: The non-power influence of the headnurseshave a director indirect positive influence on thenurses’ work engagement. Conclusion: The hospitals and nursing managers should take effective measures to promote the non-power influence, then to promote the level of nursing staffs’ work engagement, to organize and promote the nursing work of the hospital. 目的 探讨护士长非权力影响力对护士工作投入的影响。方法 对吉林省人民医院临床护理单元450名护士进行护士长非权力影响力量表和护理人员工作投入量表的问卷调查。 结果 护士长非权力影响力对护理人员工作投入具有直接和间接的正性影响。结论 医院和护理管理者应采取有效的措施提升非权力影响力,进而提升护理人员的工作投入水平,组织和推动医院护理工作
Assembly of the Lhasa and Qiangtang terranes in central Tibet by divergent double subduction
This research was financially co-supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB03010301), the National Key Project for Basic Research of China (2011CB403102 and 2015CB452604), the Chinese National Natural Science Foundation (41225006, 41472061, and 40973026), and the Specialized Research Fund for the Doctoral Program of Higher Education (20120022110001)Integration of lithostratigraphic, magmatic, and metamorphic data from the Lhasa-Qiangtang collision zone in central Tibet (including the Bangong suture zone and adjacent regions of the Lhasa and Qiangtang terranes) indicates assembly through divergent double sided subduction. This collision zone is characterized by the absence of Early Cretaceous high-grade metamorphic rocks and the presence of extensive magmatism with enhanced mantle contributions at ca. 120–110 Ma. Two Jurassic−Cretaceous magmatic arcs are identified from the Caima−Duobuza−Rongma−Kangqiong−Amdo magmatic belt in the western Qiangtang Terrane and from the Along Tso−Yanhu−Daguo−Baingoin−Daru Tso magmatic belt in the northern Lhasa Terrane. These two magmatic arcs reflect northward and southward subduction of the Bangong Ocean lithosphere, respectively. Available multidisciplinary data reconcile that the Bangong Ocean may have closed during the Late Jurassic−Early Cretaceous (most likely ca. 140–130 Ma) through arc-arc “soft” collision rather than continent-continent “hard” collision. Subduction zone retreat associated with convergence beneath the Lhasa Terrane may have driven its rifting and separation from the northern margin of Gondwana leading to its accretion within Asia.PostprintPeer reviewe
Breaking (Global) Barriers in Parallel Stochastic Optimization with Wait-Avoiding Group Averaging
Deep learning at scale is dominated by communication time. Distributing
samples across nodes usually yields the best performance, but poses scaling
challenges due to global information dissemination and load imbalance across
uneven sample lengths. State-of-the-art decentralized optimizers mitigate the
problem, but require more iterations to achieve the same accuracy as their
globally-communicating counterparts. We present Wait-Avoiding Group Model
Averaging (WAGMA) SGD, a wait-avoiding stochastic optimizer that reduces global
communication via subgroup weight exchange. The key insight is a combination of
algorithmic changes to the averaging scheme and the use of a group allreduce
operation. We prove the convergence of WAGMA-SGD, and empirically show that it
retains convergence rates similar to Allreduce-SGD. For evaluation, we train
ResNet-50 on ImageNet; Transformer for machine translation; and deep
reinforcement learning for navigation at scale. Compared with state-of-the-art
decentralized SGD variants, WAGMA-SGD significantly improves training
throughput (e.g., 2.1x on 1,024 GPUs for reinforcement learning), and achieves
the fastest time-to-solution (e.g., the highest score using the shortest
training time for Transformer).Comment: Published in IEEE Transactions on Parallel and Distributed Systems
(IEEE TPDS), vol. 32, no. 7, pp. 1725-1739, 1 July 202
Hepatitis B virus induces G1 phase arrest by regulating cell cycle genes in HepG2.2.15 cells
<p>Abstract</p> <p>Background</p> <p>To investigate the effect of HBV on the proliferative ability of host cells and explore the potential mechanism.</p> <p>Methods</p> <p>MTT, colony formation assay and tumourigenicity in nude mice were performed to investigate the effect of HBV on the proliferative capability of host cells. In order to explore the potential mechanism, cell cycle and apoptosis were analysed. The cell cycle genes controlling the G1/S phase transition were detected by immunohistochemistry, westernblot and RT-PCR.</p> <p>Results</p> <p>HepG2.2.15 cells showed decreased proliferation ability compared to HepG2 cells. G1 phase arrest was the main cause but was not associated with apoptosis. p53, p21 and total retinoblastoma (Rb) were determined to be up-regulated, whereas cyclinE was down-regulated at both the protein and mRNA levels in HepG2.2.15 cells. The phosphorylated Rb in HepG2.2.15 cells was decreased.</p> <p>Conclusions</p> <p>Our results suggested that HBV inhibited the capability of proliferation of HepG2.2.15 cells by regulating cell cycle genes expression and inducing G1 arrest.</p
Hepatitis B virus induces G1 phase arrest by regulating cell cycle genes in HepG2.2.15 cells
<p>Abstract</p> <p>Background</p> <p>To investigate the effect of HBV on the proliferative ability of host cells and explore the potential mechanism.</p> <p>Methods</p> <p>MTT, colony formation assay and tumourigenicity in nude mice were performed to investigate the effect of HBV on the proliferative capability of host cells. In order to explore the potential mechanism, cell cycle and apoptosis were analysed. The cell cycle genes controlling the G1/S phase transition were detected by immunohistochemistry, westernblot and RT-PCR.</p> <p>Results</p> <p>HepG2.2.15 cells showed decreased proliferation ability compared to HepG2 cells. G1 phase arrest was the main cause but was not associated with apoptosis. p53, p21 and total retinoblastoma (Rb) were determined to be up-regulated, whereas cyclinE was down-regulated at both the protein and mRNA levels in HepG2.2.15 cells. The phosphorylated Rb in HepG2.2.15 cells was decreased.</p> <p>Conclusions</p> <p>Our results suggested that HBV inhibited the capability of proliferation of HepG2.2.15 cells by regulating cell cycle genes expression and inducing G1 arrest.</p
White Dwarf/M Dwarf Binaries as Single Degenerate Progenitors of Type Ia Supernovae
Limits on the companions of white dwarfs in the single degenerate scenario
for the origin of Type Ia supernovae (SNIa) have gotten increasingly tight. The
only type of non-degenerate stars that survive the limits on the companions of
SNIa in SNR 0509-67.5 and SN1572 are M dwarfs. M dwarfs have special properties
that have not been considered in most work on the progenitors of SNIa: they
have small but finite magnetic fields, and they flare frequently. These
properties are explored in the context of SNIa progenitors. White dwarf/M dwarf
pairs may be sufficiently plentiful to provide an adequate rate of explosions.
Even modest magnetic fields on the white dwarf and M dwarf will yield adequate
torques to lock the two stars together, resulting in a slowly rotating white
dwarf, with the magnetic poles pointing at one another in the orbital plane.
The mass loss will be channeled by a "magnetic bottle" connecting the two
stars, landing on a concentrated polar area on the white dwarf. This enhances
the effective rate of accretion compared to spherical accretion. Luminosity
from accretion and hydrogen burning on the surface of the white dwarf may
induce self-excited mass transfer. The combined effects of self-excited mass
loss, polar accretion, and magnetic inhibition of mixing of accretion layers
give possible means to beat the "nova limit" and grow the white dwarf to the
Chandrasekhar mass even at rather moderate mass accretion rates.Comment: 32 pages, 4 figures, accepted for publication in the Astrophysical
Journa
Discovery of 90 Type Ia supernovae among 700,000 Sloan spectra: the Type-Ia supernova rate versus galaxy mass and star-formation rate at redshift ~0.1
Using a method to discover and classify supernovae (SNe) in galaxy spectra,
we find 90 Type Ia SNe (SNe Ia) and 10 Type II SNe among the ~700,000 galaxy
spectra in the Sloan Digital Sky Survey Data Release 7 that have VESPA-derived
star-formation histories (SFHs). We use the SN Ia sample to measure SN Ia rates
per unit stellar mass. We confirm, at the median redshift of the sample, z =
0.1, the inverse dependence on galaxy mass of the SN Ia rate per unit mass,
previously reported by Li et al. (2011b) for a local sample. We further
confirm, following Kistler et al. (2011), that this relation can be explained
by the combination of galaxy "downsizing" and a power-law delay-time
distribution (DTD; the distribution of times that elapse between a hypothetical
burst of star formation and the subsequent SN Ia explosions) with an index of
-1, inherent to the double-degenerate progenitor scenario. We use the method of
Maoz et al. (2011) to recover the DTD by comparing the number of SNe Ia hosted
by each galaxy in our sample with the VESPA-derived SFH of the stellar
population within the spectral aperture. In this galaxy sample, which is
dominated by old and massive galaxies, we recover a "delayed" component to the
DTD of 4.5 +/- 0.6 (statistical) +0.3 -0.5 (systematic) X 10^-14 SNe Msun^-1
yr^-1 for delays in the range > 2.4 Gyr. The mass-normalized SN Ia rate,
averaged over all masses and redshifts in our galaxy sample, is R(Ia,M,z=0.1) =
0.10 +/- 0.01 (statistical) +/- 0.01 (systematic) SNuM, and the volumetric rate
is R(Ia,V,z=0.1) = 0.247 +0.029 -0.026 (statistical) +0.016 -0.031 (systematic)
X 10^-4 SNe yr^-1 Mpc^-3. This rate is consistent with the rates and rate
evolution from other recent SN Ia surveys, which together also indicate a ~t^-1
DTD.Comment: MNRAS accepted. 20 pages, 12 figures, 5 tables. Revised following
referee report. A full version of figure 8 can be found at
http://www.astro.tau.ac.il/~orgraur/Graur_SDSS_SNe_full.pd
The delay-time distribution of type-Ia supernovae from Sloan II
We derive the delay-time distribution (DTD) of type-Ia supernovae (SNe Ia)
using a sample of 132 SNe Ia, discovered by the Sloan Digital Sky Survey II
(SDSS2) among 66,000 galaxies with spectral-based star-formation histories
(SFHs). To recover the best-fit DTD, the SFH of every individual galaxy is
compared, using Poisson statistics, to the number of SNe that it hosted (zero
or one), based on the method introduced in Maoz et al. (2011). This SN sample
differs from the SDSS2 SN Ia sample analyzed by Brandt et al. (2010), using a
related, but different, DTD recovery method. Furthermore, we use a
simulation-based SN detection-efficiency function, and we apply a number of
important corrections to the galaxy SFHs and SN Ia visibility times. The DTD
that we find has 4-sigma detections in all three of its time bins: prompt (t <
420 Myr), intermediate (0.4 2.4 Gyr),
indicating a continuous DTD, and it is among the most accurate and precise
among recent DTD reconstructions. The best-fit power-law form to the recovered
DTD is t^(-1.12+/-0.08), consistent with generic ~t^-1 predictions of SN Ia
progenitor models based on the gravitational-wave induced mergers of binary
white dwarfs. The time integrated number of SNe Ia per formed stellar mass is
N_SN/M = 0.00130 +/- 0.00015 Msun^-1, or about 4% of the stars formed with
initial masses in the 3-8 Msun range. This is lower than, but largely
consistent with, several recent DTD estimates based on SN rates in galaxy
clusters and in local-volume galaxies, and is higher than, but consistent with
N_SN/M estimated by comparing volumetric SN Ia rates to cosmic SFH.Comment: MNRAS, in pres
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