Analysis on the effect of first-in-first-out queue length ratio to the multi-hop wireless network performance

A multi-hop wireless network is created by connecting multiple wireless access points as the backhaul of the network to increase the network coverage. The issue of spatial bias, unbalanced network performance of end-to-end throughput and delay occurs when the total offered load of the associated stations exceeds the wireless link capacity. Station associated to the access point more hops away from the gateway will experiences significant amount of delay and lower end-to-end throughput compared to the station fewer hops to the gateway. To demonstrate the issue of spatial bias, a Linux based multi-hop wireless network testbed was constructed with six mesh access points (MAP) and a mesh portal. The MAP consists of two ingress interfaces (one to allow the association of station (local ingress interface) and one to allow other MAP to associate to it (mesh ingress interface)) and one egress interface to associate to another MAP. The wireless link capacity of the constructed testbed is determined by the amount of offered load that is about to congest the network. A non-congested access point has the sum of the arrival rate of both the mesh and local ingress interface not larger than the wireless link capacity. Every packet received by both the ingress interfaces of a non-congested access point will be almost immediately forwarded (packets will stay in the transmit queue awhile due to the processing delay) to the destination. However, packet received by a congested access point will be competing not to be dropped and subsequently enqueued into the transmit queue successfully. A transmit buffer (queue of waiting packets) is commonly allocated to the egress interface to fully utilize the wireless link capacity. The process of enqueueing packets into the transmit buffer is handled by a queueing manager (First-In First-Out is the queueing discipline used by the Linux queueing manager). The equality of local successful transmit probability (an) and mesh successful transmit probability (b,,) in congested MAPs, which is the main root cause of the spatial bias problem, is modelled and validated. The proposed solution for the spatial bias problem is to allocate individual transmit buffer with different successful transmit probability for the two ingress interfaces. The hypothesis, "the ratio between the length of local and mesh ingress interface queue can affect the successful transmit probability of the respective interface" is validated by three queueing configurations, namely LIOO_M500, LIO_M50 and LlO_M40 that have queues with different length ratios in congested MAPs. If packet arrival ratio of local over mesh ingress interface is larger than the respective queue length ratio, the mesh ingress interface successful transmit probability will be higher than the local ingress interface successful transmit probability. On the other hand, if packet arrival ratio of local over mesh ingress interface is smaller than (or equal to) the respective queue length ratio, the mesh ingress interface successful transmit probability will be lower than (or equal to) the local ingress interface successful transmit probability. The effect to the end-to-end throughput and delay introduced by the proposed solution is analysed. By controlling the ratio of queue lengths, the spatial bias problem in multi-hop wireless network can be alleviated

Analysis and Validation of The Effect of Various Queueing Configurations to the End-to-end Throughput of Multi-Hop Wireless Network

A multi-hop wireless network is created by connecting multiple wireless access points (APs) as the backhaul of the network to increase the network coverage. The issue of spatial bias, unbalanced network performance of end-to-end throughput and delay occurs when the total offered load of the associated stations to the backhaul exceeds the wireless link capacity. Station associated to the access point with more hops away from the gateway will experience a significant amount of delay and lower end-to-end throughput compared to the station with fewer hops to the gateway. The equality of local successful transmit probability and mesh successful transmit probability in congested APs, which is the main root cause of the spatial bias problem, is modelled and validated. If the packet arrival ratio of local over mesh ingress interface is larger than the respective queue length ratio, the mesh ingress interface successful transmit probability will be higher than the local ingress interface successful transmit probability and vice-versa. By controlling the ratio of queue lengths, stations associated to the access point with more hops away from the gateway are given higher transmit opportunity, and therefore the spatial bias problem in multi-hop wireless network can be alleviate

Factors Associated With Leisure Participation Among the Elderly Living in Long-term Care Facilities

SummaryBackgroundA lack of participation in leisure activities often leads to depression in the elderly. This study investigated the factors impacting leisure participation among the elderly living in long-term care facilities.MethodsThis cross-sectional study recruited 309 individuals older than 65 years from six long-term care facilities located in the Taipei area. Structured in-person questionnaires were administered to assess their demographic characteristics, general self-rated health status, leisure constraints, and leisure participation.ResultsThe average frequency of leisure participation was 27.20 ± 12.48 points. The top five most popular leisure activities were watching television, walking, chatting, reading, and participating in religious activities. Elderly subjects who tended to be female, have religious beliefs, have a high school education level, be married, perceive themselves in better health, demonstrate better cognitive function and have higher scores on activities of daily living and instrumental activities of daily living scales were more likely to participate in leisure activities (p < 0.05). In contrast, those who were older, had stayed in the facility for a longer time period and had more leisure constraints were less likely to participate in leisure activities (p < 0.05). Overall, the predictive factors for leisure participation included religious beliefs, educational level, cognitive skill, instrumental activities of daily living score, depression, personal inner constraints, and structural constraints. The entire model was significant (F = 11.03, p < 0.001).ConclusionBased on the self-reported interests, health status and level of cognitive skill of elderly residents, long-term care facilities should arrange appropriate leisure activities to prevent depression and to improve quality of life

Study of transforming growth factor alpha for the maintenance of human embryonic stem cells

Human embryonic stem cells (hESCs) have great potential for regenerative medicine as they have selfregenerative and pluripotent properties. Feeder cells or their conditioned medium are required for the maintenance of hESC in the undifferentiated state. Feeder cells have been postulated to produce growth factors and extracellular molecules for maintaining hESC in culture. The present study has aimed at identifying these molecules. The gene expression of supportive feeder cells, namely human foreskin fibroblast (hFF-1) and non-supportive human lung fibroblast (WI-38) was analyzed by microarray and 445 genes were found to be differentially expressed. Gene ontology analysis showed that 20.9% and 15.5% of the products of these genes belonged to the extracellular region and regulation of transcription activity, respectively. After validation of selected differentially expressed genes in both human and mouse feeder cells, transforming growth factor a (TGFa) was chosen for functional study. The results demonstrated that knockdown or protein neutralization of TGFa in hFF-1 led to increased expression of early differentiation markers and lower attachment rates of hESC. More importantly, TGFa maintained pluripotent gene expression levels, attachment rates and pluripotency by the in vitro differentiation of H9 under non-supportive conditions. TGFa treatment activated the p44/42MAPK pathway but not the PI3K/Akt pathway. In addition, TGFa treatment increased the expression of pluripotent markers, NANOG and SSEA-3 but had no effects on the proliferation of hESCs. This study of the functional role of TGFa provides insights for the development of clinical grade hESCs for therapeutic applications. © The Author(s) 2012. © Springer-Verlag 2012.published_or_final_versio

The role of stellar mass and environment for cluster blue fraction, AGN fraction and star-formation indicators from a targeted analysis of Abell 1691

We present an analysis of the galaxy population of the intermediate X-ray luminosity galaxy cluster, Abell 1691, from SDSS and Galaxy Zoo data to elucidate the relationships between environment and galaxy stellar mass for a variety of observationally important cluster populations that include the Butcher-Oemler blue fraction, the active galactic nucleus (AGN) fraction and other spectroscopic classifications of galaxies. From 342 cluster members, we determine a cluster recession velocity of 21257+/-54 km/s and velocity dispersion of 1009^+40_-36 km/s and show that although the cluster is fed by multiple filaments of galaxies it does not possess significant sub-structure in its core. We identify the AGN population of the cluster from a BPT diagram and show that there is a mild increase in the AGN fraction with radius from the cluster centre that appears mainly driven by high mass galaxies (log(stellar mass)>10.8). Although the cluster blue fraction follows the same radial trend, it is caused primarily by lower mass galaxies (log(stellar mass)<10.8). Significantly, the galaxies that have undergone recent star-bursts or are presently star-bursting but dust-shrouded (spectroscopic e(a) class galaxies) are also nearly exclusively driven by low mass galaxies. We therefore suggest that the Butcher-Oemler effect may be a mass-dependant effect. We also examine red and passive spiral galaxies and show that the majority are massive galaxies, much like the rest of the red and spectroscopically passive cluster population. We further demonstrate that the velocity dispersion profiles of low and high mass cluster galaxies are different. Taken together, we infer that the duty cycle of high and low mass cluster galaxies are markedly different, with a significant departure in star formation and specific star formation rates observed beyond r_200 and we discuss these findings.Comment: 17 pages, 14 figures (one degraded due to size constraints), accepted for publication in MNRA

Association of Female Menopause With Atrioventricular Mechanics and Outcomes

BACKGROUND: Despite known sex differences in cardiac structure and function, little is known about how menopause and estrogen associate with atrioventricular mechanics and outcomes. OBJECTIVE: To study how, sex differences, loss of estrogen in menopause and duration of menopause, relate to atrioventricular mechanics and outcomes. METHODS: Among 4051 asymptomatic adults (49.8 ± 10.8 years, 35%women), left ventricular (LV) and left atrial (LA) mechanics were assessed using speckle-tracking. RESULTS: Post-menopausal (vs. pre-menopausal) women had similar LV ejection fraction but reduced GLS, reduced PALS, increased LA stiffness, higher LV sphericity and LV torsion (all p < 0.001). Multivariable analysis showed menopause to be associated with greater LV sphericity (0.02, 95%CI 0.01, 0.03), higher indexed LV mass (LVMi), lower mitral e’, lower LV GLS (0.37, 95%CI 0.04–0.70), higher LV torsion, larger LA volume, worse PALS (∼2.4-fold) and greater LA stiffness (0.028, 95%CI 0.01–0.05). Increasing years of menopause was associated with further reduction in GLS, markedly worse LA mechanics despite greater LV sphericity and higher torsion. Lower estradiol levels correlated with more impaired LV diastolic function, impaired LV GLS, greater LA stiffness, and increased LV sphericity and LV torsion (all p < 0.05). Approximately 5.5% (37/669) of post-menopausal women incident HF over 2.9 years of follow-up. Greater LV sphericity [adjusted hazard ratio (aHR) 1.04, 95%CI 1.00–1.07], impaired GLS (aHR 0.87, 95%CI 0.78–0.97), reduced peak left atrial longitudinal strain (PALS, aHR 0.94, 95%CI 0.90–0.99) and higher LA stiffness (aHR 10.5, 95%CI 1.69–64.6) were independently associated with the primary outcome of HF hospitalizations in post-menopause. Both PALS < 23% (aHR:1.32, 95%CI 1.01–3.49) and GLS < 16% (aHR:5.80, 95%CI 1.79–18.8) remained prognostic for the incidence of HF in post-menopausal women in dichotomous analyses, even after adjusting for confounders. Results were consistent with composite outcomes of HF hospitalizations and 1-year all-cause mortality as well. CONCLUSION: Menopause was associated with greater LV/LA remodeling and reduced LV longitudinal and LA function in women. The cardiac functional deficit with menopause and lower estradiol levels, along with their independent prognostic value post-menopause, may elucidate sex differences in heart failure further

Limb development genes underlie variation in human fingerprint patterns

Fingerprints are of long-standing practical and cultural interest, but little is known about the mechanisms that underlie their variation. Using genome-wide scans in Han Chinese cohorts, we identified 18 loci associated with fingerprint type across the digits, including a genetic basis for the long-recognized “pattern-block” correlations among the middle three digits. In particular, we identified a variant near EVI1 that alters regulatory activity and established a role for EVI1 in dermatoglyph patterning in mice. Dynamic EVI1 expression during human development supports its role in shaping the limbs and digits, rather than influencing skin patterning directly. Trans-ethnic meta-analysis identified 43 fingerprint-associated loci, with nearby genes being strongly enriched for general limb development pathways. We also found that fingerprint patterns were genetically correlated with hand proportions. Taken together, these findings support the key role of limb development genes in influencing the outcome of fingerprint patterning

A Genetic Polymorphism (rs17251221) in the Calcium-Sensing Receptor Gene (CASR) Is Associated with Stone Multiplicity in Calcium Nephrolithiasis

Calcium nephrolithiasis is one of the most common causes of renal stones. While the prevalence of this disease has increased steadily over the last 3 decades, its pathogenesis is still unclear. Previous studies have indicated that a genetic polymorphism (rs17251221) in the calcium-sensing receptor gene (CASR) is associated with the total serum calcium levels. In this study, we collected DNA samples from 480 Taiwanese subjects (189 calcium nephrolithiasis patients and 291 controls) for genotyping the CASR gene. Our results indicated no significant association between the CASR polymorphism (rs17251221) and the susceptibility of calcium nephrolithiasis. However, we found a significant association between rs17251221 and stone multiplicity. The risk of stone multiplicity was higher in patients with the GG+GA genotype than in those with the AA genotype (chi-square test:P = 0.008;odds ratio  =  4.79;95% confidence interval, 1.44–15.92;Yates' correction for chi-square test:P = 0.013). In conclusion, our results provide evidence supporting the genetic effects of CASR on the pathogenesis of calcium nephrolithiasis

Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration