Bandwidth-guaranteed multicast in multi-channel multi-interface wireless mesh networks

Proceedings of the IEEE International Conference on Communications, 2009, p. 1-5We consider multi-channel multi-interface wireless mesh networks with a schedule-based MAC protocol, where conflict-free transmission is ensured by requiring links assigned with the same channel and within the mutual interference range of each other to be active at different time slots. When a (point-to-multipoint) multicast call arrives, the call is accepted if a multicast distribution tree can be established for connecting the source node with all the receiving nodes, and with sufficient bandwidth reserved on each link. Otherwise, the call is rejected. To maximize the call acceptance rate, the multicast tree must be constructed judiciously upon each call arrival. Aiming at minimizing the carried load on the most-heavily loaded channel, and maximizing the residual capacity of the most heavily loaded node, an integer linear program (ILP) is formulated for multicast tree construction. Since solving ILP can be time-consuming, an efficient heuristic algorithm is then proposed. We compare the two tree construction algorithms by simulations. We found that both algorithms give comparable call acceptance rate, but the heuristic algorithm requires much shorter running time. ©2009 IEEE.published_or_final_versio

Nonattendance in pediatric pulmonary clinics: an ambulatory survey

<p>Abstract</p> <p>Background</p> <p>Nonattendance for scheduled appointments disturbs the effective management of pediatric pulmonary clinics. We hypothesized that the reasons for non-attendance and the necessary solutions might be different in pediatric pulmonary medicine than in other pediatric fields. We therefore investigated the factors associated with nonattendance this field in order to devise a corrective strategy.</p> <p>Methods</p> <p>The effect of age, gender, ethnic origin, waiting time for an appointment and the timing of appointments during the day on nonattendance proportion were assessed. Chi-square tests were used to analyze statistically significant differences of categorical variables. Logistic regression models were used for multivariate analysis.</p> <p>Results</p> <p>A total of 1190 pediatric pulmonology clinic visits in a 21 month period were included in the study. The overall proportion of nonattendance was 30.6%. Nonattendance was 23.8% when there was a short waiting time for an appointment (1–7 days) and 36.3% when there was a long waiting time (8 days and above) (p-value < 0.001). Nonattendance was 28.7% between 8 a.m. to 3 p.m. and 37.5% after 3 p.m. (p = 0.007). Jewish rural patients had 15.4% nonattendance, Jewish urban patients had 31.2% nonattendance and Bedouin patients had 32.9% nonattendance (p < 0.004). Age and gender were not significantly associated with nonattendance proportions. A multivariate logistic regression model demonstrated that the waiting time for an appointment, time of the day, and the patients' origin was significantly associated with nonattendance.</p> <p>Conclusion</p> <p>The factors associated with nonattendance in pediatric pulmonary clinics include the length of waiting time for an appointment, the hour of the appointment within the day and the origin of the patient.</p

Treatment with methylphenidate for attention deficit hyperactivity disorder (ADHD) and the risk of all-cause poisoning in children and adolescents: a self-controlled case series study

BACKGROUND: Children and adolescents with attention deficit hyperactivity disorder (ADHD) are at higher risk of all-cause poisoning by drugs and chemicals (intentional or accidental). Currently, there is limited data on whether medication treatment for ADHD can reduce the risk of all-cause poisoning. METHODS: Patients aged 5–18 years with a methylphenidate (MPH) prescription and an incident poisoning diagnosis between January 2001 and June 2020 were identified from the Hong Kong Clinical Data Analysis and Reporting System. A self-controlled case series study design was used to compare the incidence rate ratios (IRRs) of all-cause poisoning during different risk windows (30 days before the first MPH prescription, exposure periods within 30 days of the first prescription, and periods of subsequent exposure) compared with the reference window (other non-exposure periods). RESULTS: 42,203 patients were prescribed ADHD medication in Hong Kong during the study period. Of these, 417 patients who had both an MPH prescription and poisoning incident recorded were included in the main analysis. Compared with other non-exposed periods, a higher risk of poisoning was found in the 30 days before the first prescription (IRR 2.64, 95% confidence interval [CI] 1.33–5.22) and exposure periods within 30 days of the first prescription (IRR 2.18, 95% CI 1.06–4.48), but not during prolonged exposure. However, compared with 30 days before the first prescription as well as exposure periods within 30 days of the first prescription, there was a lower risk during the subsequent exposure (IRRs 0.49 and 0.60, respectively). Similar results to the main analysis were also found in the subgroup analysis of intentional poisoning and females, but not in that of accidental poisoning and males. CONCLUSIONS: The risk of all-cause poisoning was higher shortly before and after the first MPH prescription and became lower during the subsequent prescription period. Our results do not support an association between the use of MPH and an increased risk of all-cause poisoning in children and adolescents and, in fact, suggest that longer-term use of MPH may be associated with a lower risk of all-cause poisoning, although this latter finding requires further study

Outcomes of first-ever stroke

The long-term prognosis after first-ever stroke is poor—5 years after their stroke, 39.7% of patients had died and 10.7% were dependent in terms of activity of daily living; 136 (21%) who survived at least 30 days after the initial stroke, had a recurrence within 5 years.published_or_final_versio

Impact of nutritional supplements on cognitive development of children in developing countries: A meta-analysis

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Visit-to-visit systolic blood pressure variability predicts all-cause and cardiovascular mortality after lacunar infarct

Background: Both blood pressure (BP) and its variability (BPV) are established risk factors for development of atherosclerotic disease and are associated with an increased risk for cardiovascular and all-cause mortality. The prognostic implications of out-patient clinic visit-to-visit BPV among patients with lacunar infarction are nevertheless unknown. Methods: We prospectively followed up the clinical outcome of 281 patients with lacunar infarction. The mean BP and BPV, as determined by the standard deviation of the systolic and diastolic BP, were recorded during a mean of 13 ± 6 out-patient clinic visits. Results: The mean age of the population was 70 ± 10 years. After a mean of 78 ± 18 month’s follow-up, 65 (23%) patients died, 31% (20/65) were due to cardiovascular causes. 14% and 7% developed recurrent stroke and acute coronary syndrome, respectively. After adjusting for age, sex, mean systolic and diastolic BP, cardiovascular risk factors and co-morbidities, patients with a systolic BPV of the third tertile had significantly higher risk of all-cause (hazard ratio [HR] = 1.97; 95% confidence interval [CI], 1.02-3.80; P = 0.04) and cardiovascular mortality (HR = 7.64; 95% CI, 1.65-35.41; P < 0.01) compared to those with systolic BPV of the first tertile. Nevertheless, systolic BPV did not predict recurrent stroke or acute coronary syndrome. Diastolic BPV did not predict various adverse clinical outcomes. Conclusions: Visit-to-visit systolic BPV predicts long-term all-cause and cardiovascular mortality after lacunar infarct, independent of conventional risk factors including average BP control.published_or_final_versio

Long-term prognostic implications of visit-to-visit blood pressure variability in patients with ischaemic stroke

Background: Both blood pressure (BP) and its variability (BPV) are established risk factors for the development of atherosclerotic diseases and are associated with an increased risk of cardiovascular and all-cause mortality. The long-term prognostic implications of out-patient clinic visit-to-visit BPV among patients with ischaemic stroke are nevertheless unknown. Methods: We prospectively followed up the clinical outcome of 632 consecutive ischaemic stroke patients without atrial fibrillation. The mean BP and BPV, as determined by the coefficient of variation of the systolic and diastolic BP, were recorded during a mean of 12 ± 6 outpatient clinic visits. Results: The mean age of the patients was 71 ± 11 years. After a mean of 76 ± 18 month’s follow-up, 161 (26%) patients died, 35% (56/161) were due to cardiovascular causes. 16% and 5% developed recurrent stroke and acute coronary syndrome (ACS), respectively. After adjusting for mean systolic BP and confounding variables, patients with a high systolic BPV were at significantly greater risk of cardiovascular mortality (hazard ratio [HR] = 2.36; 95% confidence interval [CI], 1.02-5.49; P < 0.05). A high systolic BPV also predicted all-cause mortality after adjusting for mean systolic BP (HR = 1.79; 95% CI, 1.16-2.75; P < 0.05). There was no association between systolic BPV with non-fatal recurrent stroke nor non-fatal ACS. A raised diastolic BPV did not predict recurrent non-fatal stroke, non-fatal ACS nor mortality. Conclusions: Visit-to-visit systolic BPV predicts long-term all-cause and cardiovascular mortality in patients with ischaemic stroke without atrial fibrillation, independent of other conventional risk factors including average BP control.published_or_final_versio