146 research outputs found
A novel consistent quality driven for JEM based distributed video coding
Β© 2019 by the authors. Distributed video coding (DVC) is an attractive and promising solution for low complexity constrained video applications, such as wireless sensor networks or wireless surveillance systems. In DVC, visual quality consistency is one of the most important issues to evaluate the performance of a DVC codec. However, it is the fact that the quality of the decoded frames that is achieved in most recent DVC codecs is not consistent and it is varied with high quality fluctuation. In this paper, we propose a novel DVC solution named Joint exploration model based DVC (JEM-DVC) to solve the problem, which can provide not only higher performance as compared to the traditional DVC solutions, but also an effective scheme for the quality consistency control. We first employ several advanced techniques that are provided in the Joint exploration model (JEM) of the future video coding standard (FVC) in the proposed JEM-DVC solution to effectively improve the performance of JEM-DVC codec. Subsequently, for consistent quality control, we propose two novel methods, named key frame quantization (KF-Q) andWyner-Zip frame quantization (WZF-Q), which determine the optimal values of the quantization parameter (QP) and quantization matrix (QM) applied for the key and WZ frame coding, respectively. The optimal values of QP and QM are adaptively controlled and updated for every key and WZ frames to guarantee the consistent video quality for the proposed codec unlike the conventional approaches. Our proposed JEM-DVC is the first DVC codec in literature that employs the JEM coding technique, and then all of the results that are presented in this paper are new. The experimental results show that the proposed JEM-DVC significantly outperforms the relevant DVC benchmarks, notably the DISCOVER DVC and the recent H.265/HEVC based DVC, in terms of both Peak signal-to-noise ratio (PSNR) performance and consistent visual quality
Beamforming Design for Wireless Information and Power Transfer Systems: Receive Power-Splitting Versus Transmit Time-Switching
Β© 1972-2012 IEEE. Information and energy can be transferred over the same radio-frequency channel. In the power-splitting (PS) mode, they are simultaneously transmitted using the same signal by the base station (BS) and later separated at the user (UE)'s receiver by a power splitter. In the time-switching (TS) mode, they are either transmitted separately in time by the BS or received separately in time by the UE. In this paper, the BS transmit beamformers are jointly designed with either the receive PS ratios or the transmit TS ratios in a multicell network that implements wireless information and power transfer (WIPT). Imposing UE-harvested energy constraints, the design objectives include: 1) maximizing the minimum UE rate under the BS transmit power constraint, and 2) minimizing the maximum BS transmit power under the UE data rate constraint. New iterative algorithms of low computational complexity are proposed to efficiently solve the formulated difficult nonconvex optimization problems, where each iteration either solves one simple convex quadratic program or one simple second-order-cone-program. Simulation results show that these algorithms converge quickly after only a few iterations. Notably, the transmit TS-based WIPT system is not only more easily implemented but outperforms the receive PS-based WIPT system as it better exploits the beamforming design at the transmitter side
Ectopic ureter associated with uterine didelphys and obstructed hemivagina: preoperative diagnosis by MRI
Uterine didelphys with obstructed hemivagina and ipsilateral renal anomalies is a rare congenital malformation of the female urogenital tract. While the urinary anomalies almost always involve renal agenesis, we report a rare case of a 17-year-old girl with the malformation associated with ectopic ureteral insertion into the obstructed hemivagina, which was diagnosed preoperatively by MR imaging. To the best of our knowledge, preoperative MR imaging diagnosis of the ectopic ureter associated with this syndrome has not been previously reported. Accurate preoperative diagnosis of ectopic ureteral insertion associated with this syndrome is important for surgical planning
Decline in mortality, AIDS, and hospital admissions in perinatally HIV-1 infected children in the United Kingdom and Ireland.
OBJECTIVE: To describe changes in demographic factors, disease progression, hospital admissions, and use of antiretroviral therapy in children with HIV. DESIGN: Active surveillance through the national study of HIV in pregnancy and childhood (NSHPC) and additional data from a subset of children in the collaborative HIV paediatric study (CHIPS). SETTING: United Kingdom and Ireland. PARTICIPANTS: 944 children with perinatally acquired HIV-1 under clinical care. MAIN OUTCOME MEASURES: Changes over time in progression to AIDS and death, hospital admission rates, and use of antiretroviral therapy. RESULTS: 944 children with perinatally acquired HIV were reported in the United Kingdom and Ireland by October 2002; 628 (67%) were black African, 205 (22%) were aged > or = 10 years at last follow up, 193 (20%) are known to have died. The proportion of children presenting who were born abroad increased from 20% in 1994-5 to 60% during 2000-2. Mortality was stable before 1997 at 9.3 per 100 child years at risk but fell to 2.0 in 2001-2 (trend P < 0.001). Progression to AIDS also declined (P < 0.001). From 1997 onwards the proportion of children on three or four drug antiretroviral therapy increased. Hospital admission rates declined by 80%, but with more children in follow up the absolute number of admissions fell by only 26%. CONCLUSION: In children with HIV infection, mortality, AIDS, and hospital admission rates have declined substantially since the introduction of three or four drug antiretroviral therapy in 1997. As infected children in the United Kingdom and Ireland are living longer, there is an increasing need to address their medical, social, and psychological needs as they enter adolescence and adult life
Use of Oral Cholera Vaccines in an Outbreak in Vietnam: A Case Control Study
Simple measures such as adequate sanitation and clean water stops the spread of cholera; however, in areas where these are not available, cholera spreads quickly and may lead to death in a few hours if treatment is not initiated immediately. The use of life-saving rehydration therapy is the mainstay in cholera control, however, the rapidity of the disease and the limited access to appropriate healthcare units in far-flung areas together result in an unacceptable number of deaths. The WHO has recommended the use of oral cholera vaccines as a preventive measure against cholera outbreaks since 2001, but this was recently updated so that vaccine use may also be considered once a cholera outbreak has begun. The findings from this study suggest that reactive use of killed oral cholera vaccines provides protection against the disease and may be a potential tool in times of outbreaks. Further studies must be conducted to confirm these findings
HCV Causes Chronic Endoplasmic Reticulum Stress Leading to Adaptation and Interference with the Unfolded Protein Response
BACKGROUND: The endoplasmic reticulum (ER) is the cellular site for protein folding. ER stress occurs when protein folding capacity is exceeded. This stress induces a cyto-protective signaling cascades termed the unfolded protein response (UPR) aimed at restoring homeostasis. While acute ER stress is lethal, chronic sub-lethal ER stress causes cells to adapt by attenuation of UPR activation. Hepatitis C virus (HCV), a major human pathogen, was shown to cause ER stress, however it is unclear whether HCV induces chronic ER stress, and if so whether adaptation mechanisms are initiated. We wanted to characterize the kinetics of HCV-induced ER stress during infection and assess adaptation mechanisms and their significance. METHODS AND FINDINGS: The HuH7.5.1 cellular system and HCV-transgenic (HCV-Tg) mice were used to characterize HCV-induced ER stress/UPR pathway activation and adaptation. HCV induced a wave of acute ER stress peaking 2-5 days post-infection, which rapidly subsided thereafter. UPR pathways were activated including IRE1 and EIF2Ξ± phosphorylation, ATF6 cleavage and XBP-1 splicing. Downstream target genes including GADD34, ERdj4, p58ipk, ATF3 and ATF4 were upregulated. CHOP, a UPR regulated protein was activated and translocated to the nucleus. Remarkably, UPR activity did not return to baseline but remained elevated for up to 14 days post infection suggesting that chronic ER stress is induced. At this time, cells adapted to ER stress and were less responsive to further drug-induced ER stress. Similar results were obtained in HCV-Tg mice. Suppression of HCV by Interferon-Ξ± 2a treatment, restored UPR responsiveness to ER stress tolerant cells. CONCLUSIONS: Our study shows, for the first time, that HCV induces adaptation to chronic ER stress which was reversed upon viral suppression. These finding represent a novel viral mechanism to manipulate cellular response pathways
Regulation of Adipocyte 11Ξ²-Hydroxysteroid Dehydrogenase Type 1 (11Ξ²-HSD1) by CCAAT/Enhancer-Binding Protein (C/EBP) Ξ² Isoforms, LIP and LAP
11Ξ²-hydroxysteroid dehydrogenase type 1 (11Ξ²-HSD1) catalyses intracellular regeneration of active glucocorticoids, notably in liver and adipose tissue. 11Ξ²-HSD1 is increased selectively in adipose tissue in human obesity, a change implicated in the pathogenesis of metabolic syndrome. With high fat (HF)-feeding, adipose tissue 11Ξ²-HSD1 is down-regulated in mice, plausibly to counteract metabolic disease. Transcription of 11Ξ²-HSD1 is directly regulated by members of the CCAAT/enhancer binding protein (C/EBP) family. Here we show that while total C/EBPΞ² in adipose tissue is unaltered by HF diet, the ratio of the C/EBPΞ² isoforms liver-enriched inhibitor protein (LIP) and liver-enriched activator protein (LAP) (C/EBPΞ²-LIP:LAP) is increased in subcutaneous adipose. This may cause changes in 11Ξ²-HSD1 expression since genetically modified C/EBPΞ²(+/L) mice, with increased C/EBPΞ²-LIP:LAP ratio, have decreased subcutaneous adipose 11Ξ²-HSD1 mRNA levels, whereas C/EBPΞ²ΞuORF mice, with decreased C/EBPΞ²-LIP:LAP ratio, show increased subcutaneous adipose 11Ξ²-HSD1. C/EBPΞ²-LIP:LAP ratio is regulated by endoplasmic reticulum (ER) stress and mTOR signalling, both of which are altered in obesity. In 3T3-L1 adipocytes, 11Ξ²-HSD1 mRNA levels were down-regulated following induction of ER stress by tunicamycin but were up-regulated following inhibition of mTOR by rapamycin. These data point to a central role for C/EBPΞ² and its processing to LIP and LAP in transcriptional regulation of 11Ξ²-HSD1 in adipose tissue. Down-regulation of 11Ξ²-HSD1 by increased C/EBPΞ²-LIP:LAP in adipocytes may be part of a nutrient-sensing mechanism counteracting nutritional stress generated by HF diet
Inter-Species Complementation of the Translocon Beta Subunit Requires Only Its Transmembrane Domain
In eukaryotes, proteins enter the secretory pathway through the translocon pore of the endoplasmic reticulum. This protein translocation channel is composed of three major subunits, called Sec61Ξ±, Ξ² and Ξ³ in mammals. Unlike the other subunits, the Ξ² subunit is dispensable for translocation and cell viability in all organisms studied. Intriguingly, the knockout of the Sec61Ξ² encoding genes results in different phenotypes in different species. Nevertheless, the Ξ² subunit shows a high level of sequence homology across species, suggesting the conservation of a biological function that remains ill-defined. To address its cellular roles, we characterized the homolog of Sec61Ξ² in the fission yeast Schizosaccharomyces pombe (Sbh1p). Here, we show that the knockout of sbh1+ results in severe cold sensitivity, increased sensitivity to cell-wall stress, and reduced protein secretion at 23Β°C. Sec61Ξ² homologs from Saccharomyces cerevisiae and human complement the knockout of sbh1+ in S. pombe. As in S. cerevisiae, the transmembrane domain (TMD) of S. pombe Sec61Ξ² is sufficient to complement the phenotypes resulting from the knockout of the entire encoding gene. Remarkably, the TMD of Sec61Ξ² from S. cerevisiae and human also complement the gene knockouts in both yeasts. Together, these observations indicate that the TMD of Sec61Ξ² exerts a cellular function that is conserved across species
Impact of Flavonoids on Cellular and Molecular Mechanisms Underlying Age-Related Cognitive Decline and Neurodegeneration
Purpose of Review This review summarises the most recent evidence regarding the effects of dietary flavonoids on age-related cognitive decline and neurodegenerative diseases. Recent Findings Recent evidence indicates that plant-derived flavonoids may exert powerful actions on mammalian cognition and protect against the development of age-related cognitive decline and pathological neurodegeneration. The neuroprotective effects of flavonoids have been suggested to be due to interactions with the cellular and molecular architecture of brain regions responsible for memory. Summary Mechanisms for the beneficial effects of flavonoids on age-related cognitive decline and dementia are discussed, including modulating signalling pathways critical in controlling synaptic plasticity, reducing neuroinflammation, promoting vascular effects capable of stimulating new nerve cell growth in the hippocampus, bidirectional interactions with gut microbiota and attenuating the extracellular accumulation of pathological proteins. These processes are known to be important in maintaining optimal neuronal function and preventing age-related cognitive decline and neurodegeneration
Inter-Species Complementation of the Translocon Beta Subunit Requires Only Its Transmembrane Domain
In eukaryotes, proteins enter the secretory pathway through the translocon pore of the endoplasmic reticulum. This protein translocation channel is composed of three major subunits, called Sec61Ξ±, Ξ² and Ξ³ in mammals. Unlike the other subunits, the Ξ² subunit is dispensable for translocation and cell viability in all organisms studied. Intriguingly, the knockout of the Sec61Ξ² encoding genes results in different phenotypes in different species. Nevertheless, the Ξ² subunit shows a high level of sequence homology across species, suggesting the conservation of a biological function that remains ill-defined. To address its cellular roles, we characterized the homolog of Sec61Ξ² in the fission yeast Schizosaccharomyces pombe (Sbh1p). Here, we show that the knockout of sbh1+ results in severe cold sensitivity, increased sensitivity to cell-wall stress, and reduced protein secretion at 23Β°C. Sec61Ξ² homologs from Saccharomyces cerevisiae and human complement the knockout of sbh1+ in S. pombe. As in S. cerevisiae, the transmembrane domain (TMD) of S. pombe Sec61Ξ² is sufficient to complement the phenotypes resulting from the knockout of the entire encoding gene. Remarkably, the TMD of Sec61Ξ² from S. cerevisiae and human also complement the gene knockouts in both yeasts. Together, these observations indicate that the TMD of Sec61Ξ² exerts a cellular function that is conserved across species
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