Leader-Contention-Based User Matching for 802.11 Multiuser MIMO Networks

In multiuser MIMO (MU-MIMO) LANs, the achievable throughput of a client depends on who are transmitting concurrently with it. Existing MU-MIMO MAC protocols however enable clients to use the traditional 802.11 contention to contend for concurrent transmission opportunities on the uplink. Such a contention-based protocol not only wastes lots of channel time on multiple rounds of contention, but also fails to maximally deliver the gain of MU-MIMO because users randomly join concurrent transmissions without considering their channel characteristics. To address such inefficiency, this paper introduces MIMOMate, a leader-contention-based MU-MIMO MAC protocol that matches clients as concurrent transmitters according to their channel characteristics to maximally deliver the MU-MIMO gain, while ensuring all users to fairly share concurrent transmission opportunities. Furthermore, MIMOMate elects the leader of the matched users to contend for transmission opportunities using traditional 802.11 CSMA/CA. It hence requires only a single contention overhead for concurrent streams, and can be compatible with legacy 802.11 devices. A prototype implementation in USRP-N200 shows that MIMOMate achieves an average throughput gain of 1.42x and 1.52x over the traditional contention-based protocol for 2-antenna and 3-antenna AP scenarios, respectively, and also provides fairness for clients.Comment: Accepted on 12-Apr-2014 for publications at IEEE Transactions on Wireless Communication

The development of the job satisfaction scale for hospital staff in Taiwan

The current study attempts to construct a valid and applicable job satisfaction scale for measuring the contentment level of hospital staff in Taiwan. The job description inventory (JDI) and Job Satisfaction Index (JSI) were adopted as the foundation of the job satisfaction measure for hospital staff in a selected hospital. To verify and validate the scale, data collected in 2012 and 2013, were analyzed using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), respectively. Subsequently, Pearson correlations analysis was used to examine the strength and direction of the relationships between job satisfaction dimensions. Overall, the job satisfaction scale developed in this research illustrated valid and accurate measure for assessing hospital staffs' satisfaction. Both EFA and CFA results demonstrated that items consistently emerged six dimensions i.e. work environment, work achievement, compensation and benefits, education and training, promotion and evaluation, and management system. The findings also highlight that management support, work achievement, and promotion and evaluation are three critical factors that significantly contribute to high levels of job satisfaction for hospital staff

Rate adaptation for 802.11 multiuser mimo networks

In multiuser MIMO (MU-MIMO) networks, the optimal bit rate of a user is highly dynamic and changes from one packet to the next. This breaks traditional bit rate adaptation algorithms, which rely on recent history to predict the best bit rate for the next packet. To address this problem, we introduce TurboRate, a rate adaptation scheme for MU-MIMO LANs. TurboRate shows that clients in a MU-MIMO LAN can adapt their bit rate on a per-packet basis if each client learns two variables: its SNR when it transmits alone to the access point, and the direction along which its signal is received at the AP. TurboRate also shows that each client can compute these two variables passively without exchanging control frames with the access point. A TurboRate client then annotates its packets with these variables to enable other clients to pick the optimal bit rate and transmit concurrently to the AP. A prototype implementation in USRP-N200 shows that traditional rate adaptation does not deliver the gains of MU-MIMO WLANs, and can interact negatively with MU-MIMO, leading to low throughput. In contrast, enabling MU-MIMO with TurboRate provides a mean throughput gain of 1.7x and 2.3x, for 2-antenna and 3-antenna APs respectively.National Science Council (China) (contract No. NSC 100-2221-E-001-005-MY2)National Science Foundation (U.S.) (NSF Grant CNS-1117194

Potential Osteoporosis Recovery by Deep Sea Water through Bone Regeneration in SAMP8 Mice

The aim of this study is to examine the therapeutic potential of deep sea water (DSW) on osteoporosis. Previously, we have established the ovariectomized senescence-accelerated mice (OVX-SAMP8) and demonstrated strong recovery of osteoporosis by stem cell and platelet-rich plasma (PRP). Deep sea water at hardness (HD) 1000 showed significant increase in proliferation of osteoblastic cell (MC3T3) by MTT assay. For in vivo animal study, bone mineral density (BMD) was strongly enhanced followed by the significantly increased trabecular numbers through micro-CT examination after a 4-month deep sea water treatment, and biochemistry analysis showed that serum alkaline phosphatase (ALP) activity was decreased. For stage-specific osteogenesis, bone marrow-derived stromal cells (BMSCs) were harvested and examined. Deep sea water-treated BMSCs showed stronger osteogenic differentiation such as BMP2, RUNX2, OPN, and OCN, and enhanced colony forming abilities, compared to the control group. Interestingly, most untreated OVX-SAMP8 mice died around 10 months; however, approximately 57% of DSW-treated groups lived up to 16.6 months, a life expectancy similar to the previously reported life expectancy for SAMR1 24 months. The results demonstrated the regenerative potentials of deep sea water on osteogenesis, showing that deep sea water could potentially be applied in osteoporosis therapy as a complementary and alternative medicine (CAM)

Structural and cognitive deficits in chronic carbon monoxide intoxication: a voxel-based morphometry study

BACKGROUND: Patients with carbon monoxide (CO) intoxication may develop ongoing neurological and psychiatric symptoms that ebb and flow, a condition often called delayed encephalopathy (DE). The association between morphologic changes in the brain and neuropsychological deficits in DE is poorly understood. METHODS: Magnetic resonance imaging and neuropsychological tests were conducted on 11 CO patients with DE, 11 patients without DE, and 15 age-, sex-, and education-matched healthy subjects. Differences in gray matter volume (GMV) between the subgroups were assessed and further correlated with diminished cognitive functioning. RESULTS: As a group, the patients had lower regional GMV compared to controls in the following regions: basal ganglia, left claustrum, right amygdala, left hippocampus, parietal lobes, and left frontal lobe. The reduced GMV in the bilateral basal ganglia, left post-central gyrus, and left hippocampus correlated with decreased perceptual organization and processing speed function. Those CO patients characterized by DE patients had a lower GMV in the left anterior cingulate and right amygdala, as well as lower levels of cognitive function, than the non-DE patients. CONCLUSIONS: Patients with CO intoxication in the chronic stage showed a worse cognitive and morphologic outcome, especially those with DE. This study provides additional evidence of gray matter structural abnormalities in the pathophysiology of DE in chronic CO intoxicated patients

6-Gingerol Inhibits Growth of Colon Cancer Cell LoVo via Induction of G2/M Arrest

6-Gingerol, a natural component of ginger, has been widely reported to possess antiinflammatory and antitumorigenic activities. Despite its potential efficacy against cancer, the anti-tumor mechanisms of 6-gingerol are complicated and remain sketchy. In the present study, we aimed to investigate the anti-tumor effects of 6-gingerol on colon cancer cells. Our results revealed that 6-gingerol treatment significantly reduced the cell viability of human colon cancer cell, LoVo, in a dose-dependent manner. Further flow cytometric analysis showed that 6-gingerol induced significant G2/M phase arrest and had slight influence on sub-G1 phase in LoVo cells. Therefore, levels of cyclins, cyclin-dependent kinases (CDKs), and their regulatory proteins involved in S-G2/M transition were investigated. Our findings revealed that levels of cyclin A, cyclin B1, and CDK1 were diminished; in contrast, levels of the negative cell cycle regulators p27Kip1 and p21Cip1 were increased in response to 6-gingerol treatment. In addition, 6-gingerol treatment elevated intracellular reactive oxygen species (ROS) and phosphorylation level of p53. These findings indicate that exposure of 6-gingerol may induce intracellular ROS and upregulate p53, p27Kip1, and p21Cip1 levels leading to consequent decrease of CDK1, cyclin A, and cyclin B1 as result of cell cycle arrest in LoVo cells. It would be suggested that 6-gingerol should be beneficial to treatment of colon cancer

Effects of Childhood Adversity and Resilience on Taiwanese Youth Health Behaviors

Adverse childhood experiences (ACEs) can leave negative impacts on one\u27s health behaviors or social functioning later in life. Resilient characteristics have been shown to mitigate effects against risk behaviors in developing adolescents. However, clinical and research attention has rarely been given to jointly consider the effects of ACEs and resilient characteristics on health behaviors in Taiwanese youth. Method: A total of 200 individuals aged 15–22 years were recruited from primary care settings, communities, and schools. Participants completed questionnaires assessing their ACEs, resilient characteristics, and health behaviors. Univariate analysis was firstly used to describe the correlates of ACEs and resilient characteristics. Further multivariate logistic regression analysis was used to examine the association of both factors with health behaviors. Results: More than half (61.5%) of those surveyed had been exposed to at least one category of ACE. Verbal (37%) and physical (21%) abuses were the most common types of ACEs. The counts in the ACE categories were associated with being involved in physical fights (odds ratio 1.28 [confidence interval 1.01–1.63]), property damage (1.29 [1.03–1.61]), running away from home (1.30 [1.05–1.60]), bullying victimization (1.37 [1.16–1.61]), and sleep problems/tiredness (1.25 [1.03–1.52]). Meanwhile, resilience scores were associated with decreased odds of infrequent seatbelt use (0.47 [0.23–0.97]), low fruit and vegetable intake (0.42 [0.21–0.86]) unsatisfied body image (0.46 [0.22–0.97]), and sleep problems/tiredness (0.37 [0.18–0.79]). Conclusions: ACEs and resilience characteristics play a significant role in shaping youth health behaviors. Further research should be undertaken to identify ways to build resilience against health risks in youth with prior ACE exposure

Poly[bis­(μ2-4,4′-bipyridine)­bis­(3-nitro­benzoato)nickel(II)]

The crystal structure of the title complex, [Ni(C7H4NO4)2(C10H8N2)2]n, exhibits a two-dimensional network, which is built up from slightly distorted NiN4O2 polyhedra (2 symmetry), bipyridine ligands, and carboxyl­ate anions. The NiII atoms are six-coordinated by two O atoms of two monodentate carboxyl­ate anions and four N atoms from bipyridine ligands and are connected into layers by the 4,4′-bipyridine ligands