Urban air pollution and chronic obstructive pulmonary disease-related emergency department visits

Background: Patients with chronic obstructive pulmonary disease (COPD) can have recurrent disease exacerbations triggered by several factors, including air pollution. Visits to the emergency respiratory department can be a direct result of short-term exposure to air pollution. The aim of this study was to investigate the relationship between the daily number of COPD emergency department visits and the daily environmental air concentrations of PM(10), SO(2), NO(2), CO and O(3) in the City of Sao Paulo, Brazil. Methods: The sample data were collected between 2001 and 2003 and are categorised by gender and age. Generalised linear Poisson regression models were adopted to control for both short-and long-term seasonal changes as well as for temperature and relative humidity. The non-linear dependencies were controlled using a natural cubic spline function. Third-degree polynomial distributed lag models were adopted to estimate both lag structures and the cumulative effects of air pollutants. Results: PM(10) and SO(2) readings showed both acute and lagged effects on COPD emergency department visits. Interquartile range increases in their concentration (28.3 mg/m(3) and 7.8 mg/m(3), respectively) were associated with a cumulative 6-day increase of 19% and 16% in COPD admissions, respectively. An effect on women was observed at lag 0, and among the elderly the lag period was noted to be longer. Increases in CO concentration showed impacts in the female and elderly groups. NO(2) and O(3) presented mild effects on the elderly and in women, respectively. Conclusion: These results indicate that air pollution affects health in a gender-and age-specific manner and should be considered a relevant risk factor that exacerbates COPD in urban environments.

Residuals for log-Burr XII regression models in survival analysis

In this paper, we compare three residuals to assess departures from the error assumptions as well as to detect outlying observations in log-Burr XII regression models with censored observations. These residuals can also be used for the log-logistic regression model, which is a special case of the log-Burr XII regression model. For different parameter settings, sample sizes and censoring percentages, various simulation studies are performed and the empirical distribution of each residual is displayed and compared with the standard normal distribution. These studies suggest that the residual analysis usually performed in normal linear regression models can be straightforwardly extended to the modified martingale-type residual in log-Burr XII regression models with censored data.

Log-modified Weibull regression models with censored data: Sensitivity and residual analysis

This paper proposes a regression model considering the modified Weibull distribution. This distribution can be used to model bathtub-shaped failure rate functions. Assuming censored data, we consider maximum likelihood and Jackknife estimators for the parameters of the model. We derive the appropriate matrices for assessing local influence on the parameter estimates under different perturbation schemes and we also present some ways to perform global influence. Besides, for different parameter settings, sample sizes and censoring percentages, various simulations are performed and the empirical distribution of the modified deviance residual is displayed and compared with the standard normal distribution. These studies suggest that the residual analysis usually performed in normal linear regression models can be straightforwardly extended for a martingale-type residual in log-modified Weibull regression models with censored data. Finally, we analyze a real data set under log-modified Weibull regression models. A diagnostic analysis and a model checking based on the modified deviance residual are performed to select appropriate models. (c) 2008 Elsevier B.V. All rights reserved.

A scheme for efficient quantum computation wtih linear optics

Quantum computers promise to increase greatly the efficiency of solving problems such as factoring large integers, combinatorial optimization and quantum physics simulation. One of the greatest challenges now is to implement the basic quantum-computational elements in a physical system and to demonstrate that they can be reliably and scalably controlled. One of the earliest proposals for quantum computation is based on implementing a quantum bit with two optical modes containing one photon. The proposal is appealing because of the ease with which photon interference can be observed. Until now, it suffered from the requirement for non-linear couplings between optical modes containing few photons. Here we show that efficient quantum computation is possible using only beam splitters, phase shifters, single photon sources and photo-detectors. Our methods exploit feedback from photo-detectors and are robust against errors from photon loss and detector inefficiency. The basic elements are accessible to experimental investigation with current technology.

Initial results of ultrasound screening for aneurysm of the abdominal aorta in Western Australia: relevance for endoluminal treatment of aneurysm disease

Background. Increased life expectancy in men during the last thirty years is largely due to the decrease in mortality from cardiovascular disease in the age group 29-69 yr. This change has resulted in a change in the disease profile of the population with conditions such as aneurysm of the abdominal aorta (AAA) becoming more prevalent. The advent of endoluminal treatment for AAA has encouraged prophylactic intervention and fuelled the argument to screen for the disease. The feasibility of inserting an endoluminal graft is dependent on the morphology and growth characteristics of the aneurysm. This study used data from a randomized controlled trial of ultrasound screening for AAA in men aged 65-83 yr in Western Australia for the purpose of determining the norms of the living anatomy in the pressurized infrarenal aorta. Aims. To examine (1) the diameters of the infra-renal aorta in aneurysmal and non-aneurysmal cases, (2) the implications for treatment modalities, with particular reference to endoluminal grafting, which is most dependent on normal and aneurysmal morphology, and (3) any evidence to support the notion that northern Europeans are predisposed to aneurysmal disease. Methods. Using ultrasound, a randomized control trial was established in Western Australia to assess the value of a screening program in males aged 65-83 yr, The infra-renal aorta was defined as aneurysmal if the maximum diameter was 30 mm or more. Aortic diameter was modelled both as a continuous tin mm) and as a binary outcome variable, for those men who had an infra-renal diameter of 30 mm or more. ANOVA and linear regression were used for modelling aortic diameter as a continuum, while chi-square analysis and logistic regression were used in comparing men with and without the diagnosis of AAA. Findings. By December 1998, of 19.583 men had been invited to undergo ultrasound screening for AAA, 12.203 accepted the invitation (corrected response fraction 70.8%). The prevalence of AAA increased with age from 4.8% at 65 yr to 10.8% at 80 yr (chi (2) = 77.9, df = 3, P<0.001). The median (IQR) diameter for the non-aneurysmal group was 21.4 mm (3.3 mm) and there was an increase (<chi>(2) = 76.0, df = 1, P<0.001) in the diameter of the infra-renal aorta with age. Since 27 mm is the 95th centile for the non-aneurysmal infra-renal aorta, a diameter of 30 mm or more is justified as defining an aneurysm. The risk of AAA was higher in men of Australian (OR = 1.0) and northern European origin (OR = 1.0, 95%CL: 0.9. 1.2) compared with those of Mediterranean origin (OR = 0.5, 99%CL: 0.4, 0.7). Conclusion. Although screening has not yet been shown to reduce mortality from AAA. these population-based data assist the understanding of aneurysmal disease and the further development and use of endoluminal grafts for this condition. (C) 2001 Published by Elsevier Science Ltd on behalf of The International Society for Cardiovascular Surgery.

Weight loss during prolonged lactation in rural Bangladeshi mothers

To determine the duration of lactation which is associated with weight loss in rural Bangladeshi mothers and also to determine the relationship with consumption patterns of principal food items, a cross-sectional study was carried out among 791 lactating rural Bangladeshi mothers aged 18-40 years. Results were compared with 333 non-pregnant and non-lactating mothers of a similar age group. The duration of lactation was up to 60 months. The mean difference in body-weight and body mass index (BMI) of lactating mothers who breastfed their children up to 24 months was significantly lower compared to non-lactating mothers of the same age group, but no differences were observed for those who breastfed beyond 24 months. The frequency of consumption of principal food items was comparable between the non-lactating and the lactating mothers who breastfed beyond 24 months. Results of multiple linear regression analysis showed that body-weight of mothers was negatively correlated with 1-12 month(s) and 13-24 months of lactation after controlling for height, education, and food consumption (slope -1.04, p < 0.05 and slope -1.23, p < 0.05 respectively). Height and consumption of meat and milk were significantly positively correlated with body-weight (slope 0.53, p < 0.001; slope 1.44, p < 0.001; and slope 0.75, p < 0.05 respectively). The study concluded that Bangladeshi women who breastfed up to 24 months were of lower weight than non-lactating mothers, most likely due to the effect of lactation. These mothers were not taking any additional foods during their lactating period. Based on the findings of the study, it is recommended that mothers consume additional energy-rich foods during the first 24 months of lactation to prevent weight loss.

Oculometric parameters of hyperopia in children with esotropic amblyopia

Purpose: To study the oculometric parameters of hyperopia in children with esotropic amblyopia, comparing amblyopic eyes with fellow eyes. Methods: Thirty-seven patients (5-8 years old) with bilateral hyperopia and esotropic amblyopia underwent a comprehensive ophthalmic examination, including cycloplegic refraction, keratometry and A-scan ultrasonography. Anterior chamber depth, lens thickness, vitreous chamber depth and total axial length were recorded. The refractive power of the crystalline lens was calculated using Bennett`s equations. Paired Student`s t-tests were used to compare ocular biometric measurements between amblyopic eyes and their fellow eyes. The associations of biometric parameters with refractive errors were assessed using Pearson correlation coefficients and linear regression. Multivariable models including axial length, corneal power and lens power were also constructed. Results: Amblyopic eyes were found to have significantly more hyperopic refraction, less corneal power, greater lens power, shorter vitreous chamber depth and shorter axial length, despite similar anterior chamber depth and lens thickness. The strongest correlation with refractive error was observed for the axial length/corneal radius ratio (r(36) = -0.92, p < 0.001 for amblyopic and r(36) = 0.87, p < 0.001 for fellow eyes). Axial length accounted for 39.2% (R(2)) of the refractive error variance in amblyopic eyes and 35.5% in fellow eyes. Adding corneal power to the model increased R(2) to 85.7% and 79.6%, respectively. A statistically significant correlation was found between axial length and corneal power, indicating decreasing corneal power with increasing axial length, and they were similar for amblyopic eyes (r(36) = 0.53,p < 0.001) and fellow eyes (r(36) = -0.57, p < 0.001). A statistically significant correlation was also found between axial length and lens power, indicating decreasing lens power with increasing axial length (r(36) = -0.72, p < 0.001 for amblyopic eyes and r(36) = -0.69, p < 0.001 for fellow eyes). Conclusions: We observed that the correlation among the major oculometric parameters and their individual contribution to hyperopia in esotropic children were similar in amblyopic and non-amblyopic eyes. This finding suggests that the counterbalancing effect of greater corneal and lens power associated with shorter axial length is similar in both eyes of patients with esotropic amblyopia.

Age-related gray matter volume changes in the brain during non-elderly adulthood

Previous magnetic resonance imaging (MRI) studies described consistent age-related gray matter (GM) reductions in the fronto-parietal neocortex, insula and cerebellum in elderly subjects, but not as frequently in limbic/paralimbic structures. However, it is unclear whether such features are already present during earlier stages of adulthood, and if age-related GM changes may follow non-linear patterns at such age range. This voxel-based morphometry study investigated the relationship between GM volumes and age specifically during non-elderly life (18-50 years) in 89 healthy individuals (48 males and 41 females). Voxelwise analyses showed significant (p < 0.05, corrected) negative correlations in the right prefrontal cortex and left cerebellum, and positive correlations (indicating lack of GM loss) in the medial temporal region, cingulate gyrus, insula and temporal neocortex. Analyses using ROI masks showed that age-related dorsolateral prefrontal volume decrements followed non-linear patterns, and were less prominent in females compared to males at this age range. These findings further support for the notion of a heterogeneous and asynchronous pattern of age-related brain morphometric changes, with region-specific non-linear features. (C) 2009 Elsevier Inc. All rights reserved.

Implications of prevalent and incident diabetes mellitus on left ventricular geometry and function in the ageing heart: The MONICA/KORA Augsburg cohort study

Background and Aim: It is unclear to what extent diabetes modulates the ageing-related adaptations of cardiac geometry and function. Methods and Results: We examined 1005 adults, aged 25-74 years, from a population-based survey at baseline in 1994/5 and at follow-up in 2004/5. We compared persistently non-diabetic individuals (ND; no diabetes at baseline and at follow-up, n = 833) with incident (ID; non-diabetic at baseline and diabetic at follow-up, n = 36) and with prevalent diabetics (PD; diabetes at baseline and follow-up examination, n = 21). Left ventricular (LV) geometry and function were evaluated by echocardiography. Statistical analyses were performed with multivariate linear regression models. Over ten years the PD group displayed a significantly stronger relative increase of LV mass (+9.34% vs. +23.7%) that was mediated by a more pronounced increase of LV end-diastolic diameter (+0% vs. +6.95%) compared to the ND group. In parallel, LA diameter increased (+4.50% vs. +12.7%), whereas ejection fraction decreased (+3.02% vs. -4.92%) more significantly in the PD group. Moreover, at the follow-up examination the PD and ID groups showed a significantly worse diastolic function, indicated by a higher E/EM ratio compared with the ND group (11.6 and 11.8 vs. 9.79, respectively). Conclusions: Long-standing diabetes was associated with an acceleration of age-related changes of left ventricular geometry accumulating in an eccentric remodelling of the left ventricle. Likewise, echocardiographic measures of systolic and diastolic ventricular function deteriorated more rapidly in individuals with diabetes. (C) 2009 Elsevier B.V. All rights reserved.

Obese Patients Have Stronger Peristalsis and Increased Acid Exposure in the Esophagus

Obesity is a risk factor for GERD and a potential modulator of esophageal motility. To assess whether obese patients differ from non-obese patients in terms of esophageal motility and reflux. Patients (n = 332) were categorized in GERD and controls after clinical assessment, esophageal manometry, and pH monitoring. Non-obese (BMI 16-29.9) and obese (BMI 30-68) were compared in regard of distal esophageal amplitude (DEA), LES pressure (LESP), manometric diagnosis, and esophageal acid exposure (EAE). Obese showed higher DEA in both controls (122 +/- A 53 vs. 97 +/- A 36 mmHg, p = 0.041) and GERD patients (109 +/- A 38 vs. 94 +/- A 46 mmHg, p < 0.001), higher LESP in GERD patients (20.5 +/- A 10.6 vs. 18.2 +/- A 10.6 mmHg, p = 0.049), higher frequency of nutcracker esophagus in controls (30 vs. 0%, p = 0.001), lower frequency of ineffective motility in GERD patients (6 vs. 20%, p = 0.001), and higher EAE in both controls [total EAE: 1.6% (0.7-5.1) vs. 0.9% (0.2-2.4), p = 0.027] and GERD patients [upright EAE: 6.5% (3.8-11.1) vs. 5.2% (1.5-10.6), p = 0.048]. Multiple linear regression showed that BMI was associated either with EAE (p < 0.001), DEA (p = 0.006), or LESP (in men, p = 0.007). Obese patients differed from non-obese in terms of esophageal motility and reflux, regardless of the presence of GERD. Obese patients showed stronger peristalsis and increased acid exposure in the esophagus.

Comparison of pelvic floor muscle strength between women undergoing vaginal delivery, cesarean section, and nulliparae using a perineometer and digital palpation

Objectives. To compare pelvic floor muscle (PFM) strength between women undergoing vaginal delivery, cesarean section, and nulliparae, investigating the factors associated with PFM strength, and observing the correlation between vaginal digital palpation and use of a perineometer. Methods. A cross-sectional study was conducted, including 31 women following vaginal delivery, 30 women following cesarean section, and 30 nulliparous women. PFM strength was measured by vaginal digital palpation and use of a perineometer. Multiple linear regression analysis with adjustment for covariables was used to compare the mean PFM strength and identify its associated factors. Results. The mean PFM strength of women undergoing vaginal delivery and cesarean section was 25.6 +/- 14.5 cmH(2)O and 39.6 +/- 22.0 cmH(2)O (p < 0.01, adjusted for covariables), respectively. A correlation was observed between measurements of PFM strength obtained by vaginal digital palpation and use of a perineometer (tau = 0.82; p < 0.01). The non-white race/ethnicity was negatively associated with PFM strength (coefficient: -10.2424; p = 0.02). Conclusions. A lower PFM strength was observed in women with a history of vaginal delivery compared to those undergoing cesarean section. Non-white race/ethnicity negatively affected PFM strength. Our data suggest that vaginal digital palpation may be used in clinical practice because of its expressive correlation with use of a perineometer.

Willingness to pay for conservation of the Asian elephant in Sri Lanka: A contingent valuation study

Results from a CVM survey of willingness to pay for the conservation of the Asian elephant of a sample of urban residents in three selected housing schemes in Colombo, the capital of Sri Lanka, are reported. Face– to–face surveys were conducted using an interview schedule. A non-linear logit regression model was constructed to analyse the respondents’ responses for the payment principle questions and to identify the factors that influence their responses. We investigate whether urban residents’ WTP for the conservation of elephants is sufficient to compensate farmers for the damage caused by elephants, and consequently to raise farmers’ tolerance of the presence of elephants on the farming fields. We find that beneficiaries (the urban residents) could compensate losers (the farmers in the HEC affected areas) and be better off than in the absence of elephants in Sri Lanka. This suggests that there is a strong economic case for the conservation of the wild elephant population in Sri Lanka. However, we have insufficient data to determine Sri Lanka’s optimal elephant population in the Kaldor-Hicks sense.

The net benefit of saving the Asian Elephant: A policy and contingent valuation Study

Reports results from a contingent valuation survey of willingness to pay for the conservation of the Asian elephant of a sample of urban residents living in three selected housing schemes in Colombo, the capital of Sri Lanka. Face–to–face surveys were conducted using an interview schedule. A non-linear logit regression model is used to analyse the respondents’ responses for the payment principle questions and to identify the factors that influence their responses. We investigate whether urban residents’ willingness to pay for the conservation of elephants is sufficient to compensate farmers for the damage caused by elephants. We find that the beneficiaries (the urban residents) could compensate losers (the farmers in the areas affected by human–elephant conflict) and be better off than in the absence of elephants in Sri Lanka. Therefore, there is a strong economic case for the conservation of the wild elephant population in Sri Lanka. However, we have insufficient data to determine the optimal level of this elephant population in the Kaldor-Hicks sense. Nevertheless, the current population of elephant in Sri Lanka is Kaldor-Hicks preferable to having none.

Non-Markovian homodyne-mediated feedback on a two-level atom: a quantum trajectory treatment

Quantum feedback can stabilize a two-level atom against decoherence (spontaneous emission), putting it into an arbitrary (specified) pure state. This requires perfect homodyne detection of the atomic emission, and instantaneous feedback. Inefficient detection was considered previously by two of us. Here we allow for a non-zero delay time tau in the feedback circuit. Because a two-level atom is a non-linear optical system, an analytical solution is not possible. However, quantum trajectories allow a simple numerical simulation of the resulting non-Markovian process. We find the effect of the time delay to be qualitatively similar to chat of inefficient detection. The solution of the non-Markovian quantum trajectory will not remain fixed, so that the time-averaged state will be mixed, not pure. In the case where one tries to stabilize the atom in the excited state, an approximate analytical solution to the quantum trajectory is possible. The result, that the purity (P = 2Tr[rho (2)] - 1) of the average state is given by P = 1 - 4y tau (where gamma is the spontaneous emission rate) is found to agree very well with the numerical results. (C) 2001 Elsevier Science B.V. All rights reserved.

Reduced Red Cell 2,3-Diphosphoglycerate Concentrations in Critical Illness without Decreased In Vivo P50

We investigated whether red cell 2,3-diphosphoglycerate (2,3-DPG) concentrations are reduced in critical illness, whether acidaemia, hypophosphataemia or anaemia influence 2,3-DPG, and whether there is any net effect on in vivo P50. Twenty healthy, non-smoking, male volunteers were compared with 20 male intensive care patients with APACHE 2 scores > 20 on the preceding day. Those transfused in this time were excluded. Venous red cell 2,3-DPG concentrations were measured in both groups. In the patient group, routine multichannel biochemical profile and arterial blood gas analysis were also performed and in vivo P50 calculated. The mean 2,3-DPG concentration was significantly lower in the patient group than in the controls (4.2 +/-1.3 mmoll/l vs 4.9 +/-0.5 mmol/l, P=0.016). The patients were well oxygenated (lowest arterial PO2=75 mm Hg) and showed a tendency to acidaemia (median pH 7.37, range 7.06 to 7.48) and anaemia (median haemoglobin concentration 113 g/l, range 89 to 154 g/l). By linear regression of patient data, pH had a significant effect on 2,3-DPG concentrations (r=0.6, P=0.011). Haemoglobin and phosphate concentrations did not, but there were few abnormal phosphate values. There was no correlation between 2,3-DPG concentrations and in vivo P50 (r(2) less than or equal to 0.08). We conclude that 2,3-DPG concentrations were reduced in a broad group of critically ill patients. Although this would normally reduce the P50, the reduction was primarily linked with acidaemia, which increases the P50. Overall, there was no net effect on the P50 and thus no affinity-related decrease in tissue oxygenation.