Impact of Queue Configuration on Service Time: Evidence from a Supermarket

We study how queue configuration affects human servers’ service time by comparing dedicated queues with shared queues using field data from a natural experiment in a supermarket. We hypothesize that queue configuration may affect servers’ service rate through several mechanisms: pooling may affect service rate directly as a result of social loafing effect and competition effect and indirectly via its impact on queue length. To investigate these impacts, we take advantage of the supermarket’s checkout layout and use a data set containing both checkout transaction details and queue information collected from video recordings in the supermarket. After we control for the queue length, we find that servers in dedicated queues are about 10.7% faster than those in shared queues, mainly because of the social loafing effect. We also demonstrate that pooling has an indirect negative effect on service time through its impact on queue length. In addition, the queue configuration’s direct effect and its indirect queue length effect function independently of each other. In aggregation, the social loafing effect dominates, and servers slow down (a 6.86% increase in service time) in shared queues.postprin

Estimation of Muscle Fiber Orientation in Ultrasound Images Using Revoting Hough Transform (RVHT)

2008-2009 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Analysis of scale effects in peer-to-peer networks

In this paper, we study both positive and negative scale effects on the operations of peer-to-peer (P2P) file sharing networks and propose the optimal sizing (number of peers) and grouping (number of directory intermediary) decisions. Using analytical models and simulation, we evaluate various performance metrics to investigate the characteristics of a P2P network. Our results show that increasing network scale has a positive effect on the expected content availability and transmission cost, but a negative effect on the expected provision and search costs. We propose an explicit expression for the overall utility of a content sharing P2P community that incorporates tradeoffs among all of the performance measures. This utility function is maximized numerically to obtain the optimal network size (or scale). We also investigate the impact of various P2P network parameters on the performance measures as well as optimal scaling decisions. Furthermore, we extend the model to examine the grouping decision in networks with symmetric interconnection structures and compare the performance between random- and location-based grouping policies. © 2008 IEEE.published_or_final_versio

Differential expression, localization and activity of two alternatively spliced isoforms of human APC regulator CDH1

The timely destruction of key regulators through ubiquitin-mediated proteolysis ensures the orderly progression of the cell cycle. The APC (anaphase-promoting complex) is a major component of this degradation machinery and its activation is required for the execution of critical events. Recent studies have just begun to reveal the complex control of the APC through a regulatory network involving WD40 repeat proteins CDC20 and CDH1. In the present paper, we report on the identification and characterization of human CDH1β, a novel alternatively spliced isoform of CDH1. Both CDH1α and CDH1β can bind to the APC and stimulate the degradation of cyclin B1, but they are differentially expressed in human tissues and cells. CDH1α contains a nuclear localization signal which is absent in CDH1β. Intracellularly, CDH1α appears in the nucleus whereas CDH1β is a predominantly cytoplasmic protein. The forced overexpression of CDH1α in cultured cells correlates with the reduction of nuclear cyclin A, but the steady-state amount of cyclin A does not change noticeably in CDH1β-overexpressed cells. In Xenopus embryos, ectopic overexpression of human CDH1α, but not of CDH1β, induces cell-cycle arrest during the first G1 phase at the midblastula transition. Taken together, our findings document the differential expression, subcellular localization and cell-cycle-regulatory activity of human CDH1 isoforms.postprin

In situ loading and delivery of short single- And double-stranded dna by supramolecular organic frameworks

Short DNA represents an important class of biomacromolecules that are widely applied in gene therapy, editing, and modulation. However, the development of simple and reliable methods for their intracellular delivery remains a challenge. Herein, we describe that seven water-soluble, homogeneous supramolecular organic frameworks (SOFs) with a well-defined pore size and high stability in water that can accomplish in situ inclusion of single-stranded (ss) and double-stranded (ds) DNA (21, 23, and 58 nt) and effective intracellular delivery (including two noncancerous and six cancerous cell lines). Fluorescence quenching experiments for single and double endlabeled ss- and ds-DNA support that the DNA sequences can be completely enveloped by the SOFs. Confocal laser scanning microscopy and flow cytometry reveal that five of the SOFs exhibit excellent delivery efficiencies that, in most of the studied cases, outperform the commercial standard Lipo2000, even at low SOF-nucleic acid ratios. In addition to high delivery efficiencies, the watersoluble, self-assembled SOF carriers have a variety of advantages, including convenient preparation, high stability, and in situ DNA inclusion, which are all critical for practical applications in nucleic acid delivery

Dynamic depth-dependent osmotic swelling and solute diffusion in articular cartilage monitored using real-time ultrasound

Author name used in this publication: Y. P. ZhengAuthor name used in this publication: J. ShiAuthor name used in this publication: S. G. Patil2003-2004 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Ethnic differences in susceptibilities to A(H1N1) flu: An epidemic parameter indicating a weak viral virulence

The current A(H1N1) flu has showed sub-population dependent susceptibility and fatality as early as April and May of 2009 in its first wave of spreading. After the pandemic outbreak spreads globally for more than seven months, the subpopulation dependence of this flu, including ethnicity, age and genderselectivity, has been recognized by several research groups. This paper attempts to discussed how to identify ethnic selectivity from the released data by WHO relevant to this ongoing flu, review some recently published papers describing the presence of ethnic differences in susceptibilities to the H1N1flu virus and further raised an argument that ethnic differences in  susceptibilities to a virus might be a piece of evidence reflecting a weak virulence of that specific virus

CDK5RAP3 is a novel repressor of p14ARF in hepatocellular carcinoma cells

CDK5 regulatory subunit associated protein 3 (CDK5RAP3) is a novel activator of PAK4 and processes important pro-metastatic function in hepatocarcinogenesis. However, it remains unclear if there are other mechanisms by which CDK5RAP3 promotes HCC metastasis. Here, we showed that in CDK5RAP3 stable knockdown SMMC-7721 HCC cells, p14(ARF) tumor suppressor was upregulated at protein and mRNA levels, and ectopic expression of CDK5RAP3 was found to repress the transcription of p14(ARF). Using chromatin immunoprecipitation assay, we demonstrated that CDK5RAP3 bound to p14(ARF) promoter in vivo. Furthermore, knockdown of p14(ARF) in CDK5RAP3 stable knockdown HCC cells reversed the suppression of HCC cell invasiveness mediated by knockdown of CDK5RAP3. Taken together, our findings provide the new evidence that overexpression of CDK5RAP3 promotes HCC metastasis via downregulation of p14(ARF).published_or_final_versio

An implementation of ultrasonic tissue elastography in a conventional ultrasound scanner

2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Preliminary research of sonomyography(SMG) based on correlation tracking

2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe