Decreasing Time Trend Research Articles

Prevalence and incidence of diabetes mellitus: a nationwide population-based pharmaco-epidemiological study in Sweden.

To investigate the changes in prevalence and incidence of pharmacologically and non-pharmacologically treated diabetes in Sweden during 2005 to 2013. We obtained data on gender, date of birth and pharmacologically and non-pharmacologically treated diabetes from national registers for all Swedish residents. During the study period a total of 240 871 new cases of pharmacologically treated diabetes was found. The age-standardized incidence during the follow-up was 4.34 and 3.16 per 1000 individuals in men and women, respectively. A decreasing time trend in incidence for men of 0.6% per year (0.994, 95% CI 0.989-0.999) and for women of 0.7% per year (0.993, 95% CI 0.986-0.999) was observed. The age-standardized prevalence increased from 41.9 and 29.9 per 1000 in 2005/2006 to 50.8 and 34.6 in 2012/2013 in men and women, respectively. This corresponds to an annually increasing time trend for both men (1.024, 95% CI 1.022-1.027) and women (1.019, 95% CI 1.016-1.021). The total age-standardized prevalence of pharmacologically and non-pharmacologically treated diabetes (2012) was 46.9 per 1000 (55.6 for men and 38.8 for women). This corresponds to an annually increasing time trend (2010-2012) for both men (1.017, 95% CI 1.013-1.021) and women (1.012, 95% CI 1.008-1.016). The prevalence of pharmacologically treated diabetes increased moderately during 8years of follow-up, while the incidence decreased modestly. This is in contrast to the results reported by most other studies. The total prevalence of diabetes (both pharmacologically and non-pharmacologically treated) in Sweden is relatively low, from a global viewpoint.

Prediction of cancer incidence in Tyrol/Austria for year of diagnosis 2020.

Prediction of the number of incident cancer cases is very relevant for health planning purposes and allocation of resources. The shift towards elder age groups in central European populations in the next decades is likely to contribute to an increase in cancer incidence for many cancer sites. In Tyrol, cancer incidence data have been registered on a high level of completeness for more than 20 years. We therefore aimed to compute well-founded predictions of cancer incidence for Tyrol for the year 2020 for all frequent cancer sites and for all cancer sites combined. After defining a prediction base range for every cancer site, we extrapolated the age-specific time trends in the prediction base range following a linear model for increasing and a log-linear model for decreasing time trends. The extrapolated time trends were evaluated for the year 2020 applying population figures supplied by Statistics Austria. Compared with the number of annual incident cases for the year 2009 for all cancer sites combined except non-melanoma skin cancer, we predicted an increase of 235 (15 %) and 362 (21 %) for females and males, respectively. For both sexes, more than 90 % of the increase is attributable to the shift toward older age groups in the next decade. The biggest increase in absolute numbers is seen for females in breast cancer (92, 21 %), lung cancer (64, 52 %), colorectal cancer (40, 24 %), melanoma (38, 30 %) and the haematopoietic system (37, 35 %) and for males in prostate cancer (105, 25 %), colorectal cancer (91, 45 %), the haematopoietic system (71, 55 %), bladder cancer (69, 100 %) and melanoma (64, 52 %). The increase in the number of incident cancer cases of 15 % in females and 21 % in males in the next decade is very relevant for planning purposes. However, external factors cause uncertainty in the prediction of some cancer sites (mainly prostate cancer and colorectal cancer) and the prediction intervals are still broad. Therefore, our predictions must be interpreted with some caution.

Epidemiological risk analysis of home injuries in Italy (1999-2006).

Home injuries are an important public health issue in both developed and developing countries. This study focused on the Italian epidemiological framework between 1999 and 2006, using a nation-representative sample provided by the National Institute of Statistics. Every year, about 3,000,000 Italian residents reported at least one home injury, with an overall annual rate of 5.2/100 (95% CI 5.1–5.4); 3.2/100 (3.0–3.4) for males and 7.2/100 (6.9–7.4) for females. Poisson regression models were used for different age-specific populations (children, young/adults and older people), to evaluate the effects of socio-demographic, health/income satisfaction and housing variables. For children, non-applicable variables (including smoking and health satisfaction) were taken as those of the head of family, while housework time was taken the family mean time. Evidence of decreasing time trend in risk of home injury was found only among young/adults (p < 0.01). The following were risk factors: female gender (adjusted relative risk—RR 2.0 for older people and RR 1.9 for young/adults, p < 0.01); one additional hour of work at home (RR 1.009, p < 0.01 for young/adults and RR 1.016, p = 0.01 for children); smoking (RR 1.3, p < 0.01 for young/adults and p = 0.02 for children); health dissatisfaction (RR 1.3, p = 0.05 for children, RR 1.6 for young/adults and RR 1.7 for older people, p < 0.01); income dissatisfaction (RR 1.2, p < 0.01 for young/adults ); living alone (RR 1.5, p < 0.01 for young/adults and RR 1.2, p < 0.02 for the older people); having a garden (RR 1.1, p < 0.01 for young/adults ). Awareness of the need for safety at home could be boosted by information campaigns on the risk, and its social cost could be reduced by specific prevention schemes. Developing tools for assessing the risk at home and for removing the main hazards would be useful for both informative and prevention interventions.

50 years of the Hungarian Congenital Abnormality Registry

The mandatory notification of patients ("cases") with different congenital abnormalities (CAs) diagnosed from birth until the end of the first postnatal year by medical doctors was ordered by the Ministry of Health in Hungary in 1962 and this CA-registry was continued as the Hungarian Congenital Abnormality Registry (HCAR) based on the international recommendation from 1970. The primary objective of the HCAR has been to determine the baseline birth prevalence rate of different CAs as reliably as possible, with three secondary objectives: (i) to detect temporal and/or spatial clusters of CAs; (ii) to evaluate increasing or decreasing time trends of CAs; and (iii) to assist in the planning of medical and social services for children and families affected by CA so that appropriate resources are allocated efficiently and effectively. This paper summarizes the activities and the evolution of the HCAR over the past 50 years (1962-2011) including the Hungarian Case-Control Surveillance of Congenital Abnormalities for postmarketing surveillance of drug teratogenicity and prevention of CAs; the special evaluation of unidentified multiple CAs; the Hungarian Surveillance of Germinal Mutations and several international collaborations. In conclusion, Hungary enjoyed optimal conditions for the HCAR due to a centralized state health system; all deliveries took place in inpatient clinics; the quality of pediatric care was high and pediatricians notified most CAs. Autopsy was mandatory in infant death, the staff of the HCAR did not consider this CA-registry only as a statistical system but the Hungarian Center for Congenital Anomaly Control and the Hungarian Case-Control Surveillance of Congenital Abnormalities based on the HCAR worked with close collaboration with the parents in order to promote the possible good quality of life of their affected children and to prevent their risk of recurrence.

Polychlorinated Biphenyls in Residential Dust: Sources of Variability

We characterized the variability in concentrations of polychlorinated biphenyls (PCBs) measured in residential dust. Vacuum cleaner samples were collected from 289 homes in the California Childhood Leukemia Study during two sampling rounds from 2001 to 2010 and 15 PCBs were measured by high resolution gas chromatography-mass spectrometry. Median concentrations of the most abundant PCBs (i.e., PCBs 28, 52, 101, 105, 118, 138, 153, and 180) ranged from 1.0-5.8 ng per g of dust in the first sampling round and from 0.8-3.4 ng/g in the second sampling round. For each of these eight PCBs, we used a random-effects model to apportion total variation into regional variability (6-11%), intraregional between-home variability (27-56%), within-home variability over time (18-52%), and within-sample variability (9-16%). In mixed-effects models, differences in PCB concentrations between homes were explained by home age, with older homes having higher PCB levels. Differences in PCB concentrations within homes were explained by decreasing time trends. Estimated half-lives ranged from 5-18 years, indicating that PCBs are removed very slowly from the indoor environment. Our findings suggest that it may be feasible to use residential dust for retrospective assessment of PCB exposures in studies of children's health.

Effect of Land-Use Change and Artificial Recharge on the Groundwater in an Arid Inland River Basin

The spatial-temporal variability of groundwater in an inland basin is very sensitive to human activity. This study focused on groundwater changes in the Alagan area within the Tarim Basin, China, with the aim of analyzing the effects of land-use change and artificial recharge on the response characteristics of groundwater. The distributed hydrological model MIKE SHE was introduced for modeling the influence of land use and artificial recharge on groundwater. Based on the runoff variation of this area, we selected three periods to simulate and analyze the response of groundwater. The results of land-use change indicated that there were significant changes from 1980 to 2000. The changed region accounted for 11.93 % of the total area, and the low coverage grasslands showed the greatest reduction. The simulation of hydrological processes before artificial recharge showed that the groundwater depths differed greatly with land-use types. Response analysis of groundwater to artificial recharge showed that the regions in which groundwater decreased were mainly distributed in grassland and bare land. Moreover, spatial autocorrelation coefficients indicated positive spatial autocorrelation of groundwater depths, but these began to reverse in 2010. Overall, land use and artificial recharge have a great influence on the time and spatial distribution of groundwater. Artificial recharge has played a positive role in improving groundwater conditions, but did not change the decreasing trend in time and space. The adaptation of environment to the decrease of groundwater presents as degradation. Groundwater conditions could be improved to some extent by the artificial recharge, but its change seems to be an irreversible process. Overall, this response study provides insight into estimations for exploration of water resources in arid areas.

Quasi-periodic imprints in the equatorial troposphere and stratosphere in three decades of reanalysis data

Wavelet analysis is applied to zonal mean zonal wind and temperature fields to represent characteristics of temporal periodic features different from the annual and semi-annual recurrence in the troposphere and stratosphere. A daily database of reanalyses is used for the period 1979–2008, which comprises the era of satellite-based data, as some discontinuities have been observed around 1978 in previous studies. Levels for this study have been chosen at 400 and 10 hPa, respectively in the middle troposphere and middle stratosphere. As representative for diverse latitudinal regions we have respectively selected 0°, ±20°, ±40°, ±60°, ±80°. Significant features were only found at the equator. The period of the quasi-biennial oscillation (QBO) is found to exhibit a decreasing trend in time over the 30 years studied. Potential harmonics of the QBO are found in the tropical stratosphere but also troposphere. However, they do not exhibit the same tendency. This fact supports in particular the idea that the QBO and the tropospheric biennial oscillation may be unrelated phenomena. Some of the observed features lie within the known range of variability of the El Nino Southern Oscillation. Faint effects of the 11-year solar cycle variability may have been observed in the troposphere and stratosphere, but no firm assertion may be made due to the low number of observed cycles for this kind of phenomenon in the used data-set time span. Short-term solar variabilities leave no relevant imprint.

Polybrominated diphenyl ethers in residential dust: Sources of variability

We characterized the sources of variability for polybrominated diphenyl ethers (PBDEs) in residential dust and provided guidance for investigators who plan to use residential dust to assess exposure to PBDEs. We collected repeat dust samples from 292 households in the Northern California Childhood Leukemia Study during two sampling rounds (from 2001 to 2007 and during 2010) using household vacuum cleaners and measured 22 PBDEs using high resolution gas chromatography–high resolution mass spectrometry. Median concentrations for individual PBDEs ranged from <0.1–2500ng per g of dust. For each of eight representative PBDEs, we used a random-effects model to apportion total variance into regional variability (0–11%), intra-regional between-household variability (17–50%), within-household variability over time (38–74%), and within-sample variability (0–23%) and we used a mixed-effects model to identify determinants of PBDE levels. Regional differences in PBDE dust levels were associated with residential characteristics that differed by region, including the presence of furniture with exposed or crumbling foam and the recent installation of carpets in the residence. Intra-regional differences between households were associated with neighborhood urban density, racial and ethnic characteristics, and to a lesser extent, income. For some PBDEs, a decreasing time trend explained a modest fraction of the within-household variability; however, most of the within-household variability was unaccounted for by our mixed-effects models. Our findings indicate that it may be feasible to use residential dust for retrospective assessment of PBDE exposures in studies of children's health (e.g., the Northern California Childhood Leukemia Study).

Polycyclic Aromatic Hydrocarbons in Residential Dust: Sources of Variability

Background: There is interest in using residential dust to estimate human exposure to environmental contaminants.Objectives: We aimed to characterize the sources of variability for polycyclic aromatic hydrocarbons (PAHs) in residential dust and provide guidance for investigators who plan to use residential dust to assess exposure to PAHs.Methods: We collected repeat dust samples from 293 households in the Northern California Childhood Leukemia Study during two sampling rounds (from 2001 through 2007 and during 2010) using household vacuum cleaners, and measured 12 PAHs using gas chromatography–mass spectrometry. We used a random- and a mixed-effects model for each PAH to apportion observed variance into four components and to identify sources of variability.Results: Median concentrations for individual PAHs ranged from 10 to 190 ng/g of dust. For each PAH, total variance was apportioned into regional variability (1–9%), intraregional between-household variability (24–48%), within-household variability over time (41–57%), and within-sample analytical variability (2–33%). Regional differences in PAH dust levels were associated with estimated ambient air concentrations of PAH. Intraregional differences between households were associated with the residential construction date and the smoking habits of residents. For some PAHs, a decreasing time trend explained a modest fraction of the within-household variability; however, most of the within-household variability was unaccounted for by our mixed-effects models. Within-household differences between sampling rounds were largest when the interval between dust sample collections was at least 6 years in duration.Conclusions: Our findings indicate that it may be feasible to use residential dust for retrospective assessment of PAH exposures in studies of health effects.

Spatial and Temporal Patterns of Bioindicator Mercury in Pennsylvania Oak Forest

We monitored spatial and temporal patterns of total Hg in forest bioindicators to assess possible local, regional, and global changes in atmospheric Hg deposition. Total Hg concentrations were monitored in leaves and fresh litterfall of northern red oak ( L.), on an epiphytic moss ( Hedw.) on northern red oak stems, and in surface soil organic matter (O and O horizons) in Pennsylvania oak-dominated forests. Variously configured plots were used to monitor Hg deposition near local coal-fired generating stations and an industrial city and along an extended regional transect. Linearly decreasing temporal trends in Hg concentrations occurred in leaves, litterfall, moss, and soil O and O. Mean annual Hg concentrations were often greater near local emissions sources compared with remote areas, especially in the initial monitoring period. Decreasing time trends for different impact areas tended to converge due to greater rates of Hg decrease where initial bioindicator Hg levels were higher. Fresh litter and soil O showed the greatest overall potential as Hg bioindicators. We conclude that Hg deposition has been significantly decreasing over time throughout the study area as a result of locally and regionally declining Hg emissions. Reductions in Hg emissions are likely a co-benefit of the 1990 Clean Air Act regulations and changing industrial activities. Recent leveling of several bioindicator Hg time trends may foretell a shift in Hg depositional patterns. Mercury monitoring studies such as this fulfill a need for documenting local and regional effects of emissions reduction.

Dynamics of functional aging based on latent-class trajectories of activities of daily living

PurposeThis study sought to identify and characterize major patterns of functional aging based on activities of daily living (ADL). MethodsWe followed 754 community-living adults aged 70 years or older monthly for ADLs, instrumental ADLs, hospitalization and restricted activity over 10 years. A generalized growth mixture model was used to identify trajectories of ADL disability across seven 18-month intervals. Cumulative burdens of disability and morbidity from different trajectories were examined using a generalized estimating equation Poisson model. ResultsFive distinct trajectories emerged. The predominant trajectory maintained ADL independence, with membership probability being 61.6%. The remaining trajectories either stayed at low (1 or 2 ADLs, 13.6%) or high (3 or 4 ADLs, 7.0%) levels of disability or declined gradually toward low (11.2%) or high (6.5%) disability. The independent trajectory was associated with the lowest burdens of disability and morbidity and a decreasing time trend of restricted activity, whereas the high disability trajectory demonstrated opposite trends. About 31% of the cohort remained in the same trajectory throughout the follow-up period. ConclusionsThe course of functional aging is heterogeneous and dynamic. Although most older adults maintain functional autonomy, some may experience persistent disability or progress toward severe disability with substantial morbidity.

Tuberkuloza - 60 godina sistematske primene vakcine Bacille Calmette Guerin u Srbiji

Bacille Calmette-Guérin (BCG) vaccine is one of the most widely used vaccines in the world and is currently given to children at birth or soon after birth in over 100 countries, including Serbia, to minimize the risk of developing serious forms of tuberculosis (TB). Despite different data about its efficacy, it is evident that BCG protects infants from disseminated and meningeal TB (there is a decreasing trend of such cases over the past six decades in Serbia) and TB - related death. Serbia is an intermediate-to-low TB incidence country in socio-economic transition. Its current epidemiologic situation when it comes to TB shows a slightly decreasing overall trend of TB, a constant decreasing time trend of childhood TB as well as a dramatically increasing trend of TB in the elderly. Some forms of extra - pulmonary TB are on the increase as well. At the beginning of the 21st century, BCG is a useful resource for individual protection in particular situations where the spread of TB infection and disease and the limited application of preventive measures cannot provide an objective control of TB.

Heterogeneous technology and the technological catching-up hypothesis: Theory and assessment in the case of MENA countries

Long run convergence implies that the convergence hypothesis will be rejected if the income differential is not stationary. However, this definition is valid only if the catching-up process between the two countries is already over. If we take into account catching-up dynamics, then poorest countries should obtain a faster growth than developed countries. Thus, income gaps should integrate decreasing time trends. We formalise this hypothesis theoretically using a stochastic neoclassical growth model with heterogeneous technology. We then apply this model to the issue of per-capita GDP catching-up of eight MENA countries towards the level of income in Europe. We approximate the nonlinear deterministic trend by a linear function with breaks and apply panel unit root tests with breaks. The analysis reveals firstly that the periods of divergence outnumber the periods of convergence. Secondly, since the year 2000 all countries but Syria have been converging toward the European per-capita income level.

Skeletal morbidity rates over time in patients with bone metastases from solid tumors reported in bone modifying agents randomised trials

ObjectiveSkeletal related events (SREs) are common in patients with bone metastases and lead to decreased quality of life and functional status. The definition of an SRE has evolved over the years and now excludes hypercalcemia of malignancy due to its low incidence. The purpose of this review was to investigate if advances in bone-targeted therapies have decreased skeletal morbidity rates (SMR) over time. MethodsA literature search was conducted in several databases to identify phase III results from bone-targeted therapy trials from 1980 through September 2011. Graphs were created to document the trends of the natural log of SMR over the mean time of enrolment for all placebo and intervention arms. Statistical hypothesis testing was employed to account for confounding factors. ResultsA total of 14 studies were identified which reported the SMR from phase III trials from 1990 to 2007. A statistically significant downward trend was observed in the placebo arms of trials over time; a similar trend was seen in all intervention arms. In a direct comparison of intervention against placebo arms, it was found that there was a significant decreasing time trend (p<0.0001) and a significant departure in SMR from placebo to intervention arms (p=0.0348). These results were seen even after accounting for the confounding factors of histology and differences in drugs. ConclusionThe decrease in SMR over time may not only be a result of advancements with bone targeted agents, but also due to better management and awareness of events associated with bone metastases.

Decreasing time trend in SSI incidence for orthopaedic procedures: surveillance matters!

Infection is the most common reason for early revision after hip and knee arthroplasty, and the revision rate is increasing. Surgical site infection (SSI) surveillance data are important to assess the true infection rate. There is little information regarding the potential time trend in SSI incidence following orthopaedic surgery. To evaluate whether a time trend exists in SSI incidence due to surveillance following orthopaedic surgery. The SSI rates after hip and knee replacements and osteosynthesis of trochanteric femoral fractures and ankle fractures were recorded prospectively from May 1998 to October 2008 according to the criteria of the US Centers for Disease Control and Prevention. In total, 4177 procedures were analysed, 65.8% of which were performed on female patients. Linear regression was used to analyse trends in SSI rates. SSI incidence decreased significantly from 7% in the first year to 3% in the last year; a 57% relative reduction. The duration of surgery was the only significant predictor for infection (P < 0.001) in a logistic regression model that also included age, American Society of Anesthesiologists' score and level of emergency. Surveillance following orthopaedic procedures showed a significant decrease in SSI incidence over the 11-year surveillance period. The causality between surveillance and SSI incidence is difficult to prove, but surveillance with feedback probably influences several procedures that affect the quality of health care, even if duration of surgery is the only significant predictor of this effect.

Upper gastrointestinal bleeding associated with NSAIDs, other drugs and interactions: a nested case–control study in a new general practice database

To test the ability a new Spanish primary care research database (BIFAP) to capture the association between upper gastrointestinal bleeding (UGIB) and NSAIDs and other drugs and compare the results with previous studies. We performed a nested case-control study in persons aged 40-90 years old included in the period 2001-2005. Potential cases were selected through a computer search followed by an individual blinded review. Controls matched for age, sex and calendar year were randomly selected. The exposure window was defined as 0-30 days before the index date. Adjusted odds ratios were obtained through unconditional logistic regression models. In a study cohort of 669,115 subjects (1,576,442 person-years) we retrieved 1,193 valid incident cases. Increased risks were found with current use of NSAIDs (RR = 1.72; 95 %CI: 1.41-2.09), metamizole (1.52; 1.09-2.13), low-dose aspirin (1.74; 1.37-2.21), other antiplatelet drugs (1.73; 1.27-2.36), and oral anticoagulants (2.00; 1.44-2.77). We did not find an increased risk with current use of oral corticosteroids (1.11; 0.66-1.86), SSRIs (1.05; 0.77-1.42), or paracetamol (1.00; 0.82-1.23). Acid-suppressing drugs reduced the risk among users of NSAIDs (0.58; 0.39-0.85), particularly in users with antecedents of peptic ulcer (0.16; 0.05-0.58). We detected a decreasing time-trend in the relative risk and the population attributable proportion associated with NSAIDs over the study period. The increased risk of UGIB associated with NSAIDs was lower than previously reported, which could partly be explained by methodological differences, but a decreasing burden over time of this drug safety problem is suggested. BIFAP has shown to be a valuable tool for pharmacoepidemiological research.

A widespread decrease in productivity of sockeye salmon (Oncorhynchus nerka) populations in western North America

We used data on 64 stocks of sockeye salmon ( Oncorhynchus nerka ) from British Columbia (B.C.), Washington, and Alaska to determine whether recent decreases in abundance and productivity observed for Fraser River, B.C., sockeye have occurred more widely. We found that decreasing time trends in productivity have occurred across a large geographic area ranging from Washington, B.C., southeast Alaska, and up through the Yakutat peninsula, Alaska, but not in central and western Alaska. Furthermore, a pattern of predominantly shared trends across southern stocks and opposite trends between them and stocks from western Alaska was present in the past (1950–1985), but correlations have intensified since then. The spatial extent of declining productivity of sockeye salmon has important implications for management as well as research into potential causes of the declines. Further research should focus on mechanisms that operate at large, multiregional spatial scales, and (or) in marine areas where numerous correlated sockeye stocks overlap.

Suicide of first-generation immigrants in Australia, 1974–2006

This study analysed suicide rates among first-generation immigrants in Australia from 1974 to 2006, and compared their suicide risks against the Australian-born population. It also examined the associations between the suicide rates of immigrants from 23 selected countries of birth during 2001-2006, and in their home countries. Age-standardised suicide rates (15+ years) and rate ratios, with a 95 % confidence interval, during 1974-2006 were calculated for country of birth (COB) groups. Spearman's rank correlation coefficient was calculated between COB-specific immigrant suicide rates during 2001-2006 in Australia and in their homelands. Suicide rates showed a decreasing time-trend among all COB groups for both genders in Australia. The lowest suicide rates were found during 2004-2006, compared to other year groups. Throughout the study period, males born in Eastern, Northern and Western Europe and New Zealand had the highest suicide rates in Australia. For females, the highest rates were among those born in Western Europe and the UK (including Ireland). Male and female migrants born in North Africa and the Middle East, Southern and Central Asia and South East Asia showed the lowest suicide rates. There was a significant correlation between male immigrant suicide rates by COB and the rates of their home countries. The patterns of suicide rates in immigrants were influenced by the social and cultural norms of their COB. The overall decrease in suicide risk among immigrants was particularly evident in males.

Spatiotemporal Quantile Regression for Detecting Distributional Changes in Environmental Processes

Climate change may lead to changes in several aspects of the distribution of climate variables, including changes in the mean, increased variability, and severity of extreme events. In this paper, we propose using spatiotemporal quantile regression as a flexible and interpretable method for simultaneously detecting changes in several features of the distribution of climate variables. The spatiotemporal quantile regression model assumes that each quantile level changes linearly in time, permitting straight-forward inference on the time trend for each quantile level. Unlike classical quantile regression which uses model-free methods to analyze a single quantile or several quantiles separately, we take a model-based approach which jointly models all quantiles, and thus the entire response distribution. In the spatiotemporal quantile regression model, each spatial location has its own quantile function that evolves over time, and the quantile functions are smoothed spatially using Gaussian process priors. We propose a basis expansion for the quantile function that permits a closed-form for the likelihood, and allows for residual correlation modeling via a Gaussian spatial copula. We illustrate the methods using temperature data for the southeast US from the years 1931-2009. For these data, borrowing information across space identifies more significant time trends than classical non-spatial quantile regression. We find a decreasing time trend for much of the spatial domain for monthly mean and maximum temperatures. For the lower quantiles of monthly minimum temperature, we find a decrease in Georgia and Florida, and an increase in Virginia and the Carolinas.

Temporal trend of mercury in polar bears (Ursus maritimus) from Svalbard using teeth as a biomonitoring tissue

We examined the use of mercury (Hg) and nitrogen and carbon stable isotopes in teeth of polar bear (Ursus maritimus) from Svalbard as biotracers of temporal changes in Hg pollution exposure between 1964 and 2003. Teeth were regarded as a good matrix of the Hg exposure, and in total 87 teeth of polar bears were analysed. Dental Hg levels ranged from 0.6 to 72.3 ng g(-1) dry weight and increased with age during the first 10 years of life. A decreasing time trend in Hg concentrations was observed over the recent four decades while no temporal changes were found in the stable isotope ratios of nitrogen (δ(15)N) and carbon (δ(13)C). This suggests that the decrease of Hg concentrations over time was more likely due to a lower environmental Hg exposure in this region rather than a shift in the feeding habits of Svalbard polar bears.