617 research outputs found
Disassortative mixing in online social networks
The conventional wisdom is that social networks exhibit an assortative mixing
pattern, whereas biological and technological networks show a disassortative
mixing pattern. However, the recent research on the online social networks
modifies the widespread belief, and many online social networks show a
disassortative or neutral mixing feature. Especially, we found that an online
social network, Wealink, underwent a transition from degree assortativity
characteristic of real social networks to degree disassortativity
characteristic of many online social networks, and the transition can be
reasonably elucidated by a simple network model that we propose. The relations
among network assortativity, clustering, and modularity are also discussed in
the paper.Comment: 6 pages, 5 figures, 1 tabl
The Peahenâs Tale, or Dressing Our Parts at Work
However, there may ultimately be no logical way to reconcile decisions that prohibit employers from requiring women to wear revealing outfits and others that permit employers to require them to wear makeup,20 or decisions that prohibit penalizing a woman for being insufficiently feminine and others that permit penalizing a man for being insufficiently masculine.21 In addition, the increasing judicial acceptance of the sex stereotyping theory of sex discrimination under Title VII is in substantial tension with recent cases that insist that sex-differentiated dress and grooming requirements that merely 22 conform to existing social gender norms do not amount to impermissible sex discrimination. Because dress is so crucial a characteristic in sexually dimorphic species, and because it is so closely tied to sexual attractiveness, choice, and power dynamics, employers should be prohibited from requiring women to dress in gender normative ways that reflect those traits even if they believe that such dress codes do not amount to intentional sex stereotyping.223 Where, as here, so many threads come together to demonstrate that sex differences in dress are likely to affect the way that individuals are treated by others, employers should not be permitted to mandate differences that implicate notions of attractiveness or power
How people make friends in social networking sites - A microscopic perspective
We study the detailed growth of a social networking site with full temporal
information by examining the creation process of each friendship relation that
can collectively lead to the macroscopic properties of the network. We first
study the reciprocal behavior of users, and find that link requests are quickly
responded to and that the distribution of reciprocation intervals decays in an
exponential form. The degrees of inviters/accepters are slightly negatively
correlative with reciprocation time. In addition, the temporal feature of the
online community shows that the distributions of intervals of user behaviors,
such as sending or accepting link requests, follow a power law with a universal
exponent, and peaks emerge for intervals of an integral day. We finally study
the preferential selection and linking phenomena of the social networking site
and find that, for the former, a linear preference holds for preferential
sending and reception, and for the latter, a linear preference also holds for
preferential acceptance, creation, and attachment. Based on the linearly
preferential linking, we put forward an analyzable network model which can
reproduce the degree distribution of the network. The research framework
presented in the paper could provide a potential insight into how the
micro-motives of users lead to the global structure of online social networks.Comment: 10 pages, 12 figures, 2 table
Individual popularity and activity in online social systems
We propose a stochastic model of web user behaviors in online social systems,
and study the influence of attraction kernel on statistical property of user or
item occurrence. Combining the different growth patterns of new entities and
attraction patterns of old ones, different heavy-tailed distributions for
popularity and activity which have been observed in real life, can be obtained.
From a broader perspective, we explore the underlying principle governing the
statistical feature of individual popularity and activity in online social
systems and point out the potential simple mechanism underlying the complex
dynamics of the systems.Comment: 7 pages, 7 figures, 1 table, accepted for publication in Physica
Challenges and Opportunities for Second-life Batteries: A Review of Key Technologies and Economy
Due to the increasing volume of Electric Vehicles in automotive markets and
the limited lifetime of onboard lithium-ion batteries (LIBs), the large-scale
retirement of LIBs is imminent. The battery packs retired from Electric
Vehicles still own 70%-80% of the initial capacity, thus having the potential
to be utilized in scenarios with lower energy and power requirements to
maximize the value of LIBs. However, spent batteries are commonly less reliable
than fresh batteries due to their degraded performance, thereby necessitating a
comprehensive assessment from safety and economic perspectives before further
utilization. To this end, this paper reviews the key technological and economic
aspects of second-life batteries (SLBs). Firstly, we introduce various
degradation models for first-life batteries and identify an opportunity to
combine physics-based theories with data-driven methods to establish
explainable models with physical laws that can be generalized. However,
degradation models specifically tailored to SLBs are currently absent.
Therefore, we analyze the applicability of existing battery degradation models
developed for first-life batteries in SLB applications. Secondly, we
investigate fast screening and regrouping techniques and discuss the regrouping
standards for the first time to guide the classification procedure and enhance
the performance and safety of SLBs. Thirdly, we scrutinize the economic
analysis of SLBs and summarize the potentially profitable applications.
Finally, we comprehensively examine and compare power electronics technologies
that can substantially improve the performance of SLBs, including
high-efficiency energy transformation technologies, active equalization
technologies, and technologies to improve reliability and safety
Concentration-dependent effects of narciclasine on cell cycle progression in Arabidopsis root tips
<p>Abstract</p> <p>Background</p> <p>Narciclasine (NCS) is an Amaryllidaceae alkaloid isolated from <it>Narcissus tazetta </it>bulbs. NCS has inhibitory effects on a broad range of biological activities and thus has various potential practical applications. Here we examine how NCS represses plant root growth.</p> <p>Results</p> <p>Results showed that the inhibition of NCS on cell division in <it>Arabidopsis </it>root tips and its effects on cell differentiation are concentration-dependent; at low concentrations (0.5 and 1.0 ÎŒM) NCS preferentially targets mitotic cell cycle specific/cyclin complexes, whereas at high concentration (5.0 ÎŒM) the NCS-stimulated accumulation of Kip-related proteins (KRP1 and RP2) affects the CDK complexes with a role at both G1/S and G2/M phases.</p> <p>Conclusions</p> <p>Our findings suggest that NCS modulates the coordination between cell division and differentiation in <it>Arabidopsis </it>root tips and hence affects the postembryonic development of <it>Arabidopsis </it>seedlings.</p
AG-CRC: Anatomy-Guided Colorectal Cancer Segmentation in CT with Imperfect Anatomical Knowledge
When delineating lesions from medical images, a human expert can always keep
in mind the anatomical structure behind the voxels. However, although
high-quality (though not perfect) anatomical information can be retrieved from
computed tomography (CT) scans with modern deep learning algorithms, it is
still an open problem how these automatically generated organ masks can assist
in addressing challenging lesion segmentation tasks, such as the segmentation
of colorectal cancer (CRC). In this paper, we develop a novel Anatomy-Guided
segmentation framework to exploit the auto-generated organ masks to aid CRC
segmentation from CT, namely AG-CRC. First, we obtain multi-organ segmentation
(MOS) masks with existing MOS models (e.g., TotalSegmentor) and further derive
a more robust organ of interest (OOI) mask that may cover most of the
colon-rectum and CRC voxels. Then, we propose an anatomy-guided training patch
sampling strategy by optimizing a heuristic gain function that considers both
the proximity of important regions (e.g., the tumor or organs of interest) and
sample diversity. Third, we design a novel self-supervised learning scheme
inspired by the topology of tubular organs like the colon to boost the model
performance further. Finally, we employ a masked loss scheme to guide the model
to focus solely on the essential learning region. We extensively evaluate the
proposed method on two CRC segmentation datasets, where substantial performance
improvement (5% to 9% in Dice) is achieved over current state-of-the-art
medical image segmentation models, and the ablation studies further evidence
the efficacy of every proposed component.Comment: under revie
New risk score for predicting progression of membranous nephropathy
Abstract
Background
Patients with Idiopathic membranous nephropathy (IMN) have various outcomes. The aim of this study is to construct a tool for clinicians to precisely predict outcome of IMN.
Methods
IMN patients diagnosed by renal biopsy from Shanghai Ruijin Hospital from 2009.01 to 2013.12 were enrolled in this study. Primary outcome was defined as a combination of renal function progression [defined as a reduction of estimated glomerular filtration rate (eGFR) equal to or over 30% comparing to baseline], ESRD or death. Risk models were established by Cox proportional hazard regression analysis and validated by bootstrap resampling analysis. ROC curve was applied to test the performance of risk score.
Results
Totally 439 patients were recruited in this study. The median follow-up time was 38.73â±â19.35 months. The enrolled patients were 56 (15â83) years old with a male predominance (sex ratio: male vs female, 1:0.91). The median baseline serum albumin, eGFR-EPI and proteinuria were 23(8â43) g/l, 100.31(12.81â155.98) ml/min/1.73 m2 and 3.98(1.50â22.98) g/24 h, respectively. In total, there were 36 primary outcomes occurred. By Cox regression analysis, the best risk model included age [HR: 1.04(1.003â1.08), 95% CI from bootstrapping: 1.01â1.08), eGFR [HR: 0.97 (0.96â0.99), 95% CI from bootstrapping: 0.96â0.99) and proteinuria [HR: 1.09 (1.01â1.18), 95% CI from bootstrapping: 1.02â1.16). One unit increasing of the risk score based on the best model was associated with 2.57 (1.97â3.36) fold increased risk of combined outcome. The discrimination of this risk score was excellent in predicting combined outcome [C statistics: 0.83, 95% CI 0.76â0.90].
Conclusions
Our study indicated that older IMN patients with lower eGFR and heavier proteinuria at the time of renal biopsy were at a higher risk for adverse outcomes. A risk score based on these three variables provides clinicians with an effective tool for risk stratification.https://deepblue.lib.umich.edu/bitstream/2027.42/147736/1/12967_2019_Article_1792.pd
The effect of health insurance reform on the number of cataract surgeries in Chongqing, China
<p>Abstract</p> <p>Background</p> <p>Cataracts are the leading cause of blindness in China, and poverty is a major barrier to having cataract surgery. In 2003, the Chinese government began a series of new national health insurance reforms, including the New Cooperative Medical Scheme (NCMS) and the Urban Resident Basic Health Insurance scheme (URBMI). These two programs, combined with the previously existing Urban Employee Basic Health Insurance (UEBMI) program, aimed to make it easier for individuals to receive medical treatment. This study reports cataract surgery numbers in rural and urban populations and the proportion of these who had health insurance in Chongqing, China from 2003 to 2008.</p> <p>Methods</p> <p>The medical records of a consecutive case series, including 14,700 eyes of 13,262 patients who underwent age-related cataract surgery in eight hospitals in Chongqing from January 1, 2003, to December 31, 2008, were analysed retrospectively via multi-stage cluster sampling.</p> <p>Results</p> <p>In the past six years, the total number of cataract surgeries had increased each year as had the number of patients with insurance. Both the number of surgeries and the number of insured patients were much higher in the urban group than in the rural group. The rate of increase in the rural group however was much higher than in the urban group, especially in 2007 and 2008. The odds ratios of having health insurance for urban vs. rural individuals were relatively stable from 2003 to 2006, but it decreased in 2007 and was significantly lower in 2008.</p> <p>Conclusions</p> <p>Health insurance appears to be an important factor associated with increased cataract surgery in Chongqing, China. With the implementation of health insurance, the number of Chongqing's cataract surgeries was increased year by year.</p
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