Seasonal variation of serotonin turnover in human cerebrospinal fluid, depressive symptoms and the role of the 5-HTTLPR.

Studying monoaminergic seasonality is likely to improve our understanding of neurobiological mechanisms underlying season-associated physiological and pathophysiological behavior. Studies of monoaminergic seasonality and the influence of the serotonin-transporter-linked polymorphic region (5-HTTLPR) on serotonin seasonality have yielded conflicting results, possibly due to lack of power and absence of multi-year analyses. We aimed to assess the extent of seasonal monoamine turnover and examined the possible involvement of the 5-HTTLPR. To determine the influence of seasonality on monoamine turnover, 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) were measured in the cerebrospinal fluid of 479 human subjects collected during a 3-year period. Cosine and non-parametric seasonal modeling were applied to both metabolites. We computed serotonin (5-HT) seasonality values and performed an association analysis with the s/l alleles of the 5-HTTLPR. Depressive symptomatology was assessed using the Beck Depression Inventory-II. Circannual variation in 5-HIAA fitted a spring-peak cosine model that was significantly associated with sampling month (P=0.0074). Season of sampling explained 5.4% (P=1.57 × 10(-7)) of the variance in 5-HIAA concentrations. The 5-HTTLPR s-allele was associated with increased 5-HIAA seasonality (standardized regression coefficient=0.12, P=0.020, N=393). 5-HIAA seasonality correlated with depressive symptoms (Spearman's rho=0.13, P=0.018, N=345). In conclusion, we highlight a dose-dependent association of the 5-HTTLPR with 5-HIAA seasonality and a positive correlation between 5-HIAA seasonality and depressive symptomatology. The presented data set the stage for follow-up in clinical populations with a role for seasonality, such as affective disorders

Seasonality of Deaths in the U.S. by Age and Cause

In this paper, we analyze seasonality of deaths by age and cause in the U.S. using public use files for the years 1994 to 1998 by the methods of regression and a variation of Census Method II. We answer the following questions: For each age cohort, how much does each cause of death contribute to seasonality of deaths? What is the reason for the variation in seasonality of deaths with respect to age? We also analyze death records of Social Security Administration over a longer time period to examine how seasonality of deaths has changed since the mid-1970’s. We found that in general, the degree of seasonality in deaths has decreased over time for younger cohorts and has increased over time for older cohorts.mortality, seasonality

Cost-Based Model of Seasonal Production, with Application to Milk Policy, A

Milk production is seasonal in many European countries. While quantity seasonality poses capacity management problems for dairy processors, a European Union policy goal is to reduce price seasonality. After developing a model of endogenous seasonality, we study the effects of three E.U. policies on production decisions. These are private storage subsidies, production removals, and production quotas. When cost functions are seasonal in a specified way, then arbitrage opportunities interact with storage subsidies to reduce both price and consumption seasonality. But production seasonality likely increases because storage subsidies promote temporal market integration. Conditions are identified under which product market interventions increase quantity seasonality.efficiency, market intervention, quota, stabilization, storage subsidies.

The causes and consequences of seasonal variation in COPD exacerbations

Gavin C Donaldson, Jadwiga A Wedzicha Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, UK Abstract: The time of year when patients experience exacerbations of chronic obstructive pulmonary disease is a much-overlooked feature of the disease. The higher incidence of exacerbations in winter has important consequences for patients in terms of increased morbidity and mortality. The seasonality also imposes a considerable burden on already-overloaded health care services, with both primary care consultations and hospital admissions increasing in number. The seasonality of exacerbations varies with latitude, and is greater in more temperate climates, where there may be less protection from outdoor and indoor cold exposure. The precise causes of the seasonality are unknown, but thought to be partly due to the increased prevalence of respiratory viral infections circulating in cold, damp conditions. Increased susceptibility to viral infection may also be a mechanism mediated through increased airway inflammation or possibly reduced vitamin D levels. The seasonality of exacerbations informs us about the triggers of exacerbations and suggests possible strategies to reduce their number. Keywords: exacerbations of COPD, seasonality, winter mortality, winter morbidit

How does the seasonality influence utilitarian walking behaviour in different urbanization settings in Scotland?

The relationship between the built environment and walking has been analyzed for decades. However, the seasonality effects on the relationship between the built environment and walking have not been well examined even though weather is one of the key determinants of walking. Therefore, this study used 2007–8 Scottish Household Survey data collected over two years and estimated the interaction effects between the urbanization setting (i.e., residential locations: urban, town and rural areas) and seasons (i.e., spring, summer, autumn and winter) on walking. Scottish Urban-rural classification scheme is measured based on the population and access to large cities, and used as a key independent variable. The number of walking days for specific purposes such as work or shopping (utilitarian walking) during the past 7 days is used as a dependent variable. The results show that there are significant geographical variations of seasonality effect on utilitarian walking. That is, people living in rural areas are more sensitive to seasonality impacts than those living in urban areas. In addition, we found that the association between urbanization setting and utilitarian walking varies across seasons, indicating that their relationship can be miss-estimated if we ignore the seasonality effects. Therefore, policy makers and practitioners should consider the seasonality effects to evaluate the effectiveness of land use policy correctly. Finally, we still find the significant association between the urbanization setting and utilitarian walking behaviour with the consideration of seasonality effects, supporting the claim of New Urbanism

AN EVALUATION OF THE EFFECTIVENESS OF THE FLORIDA COOPERATIVE'S SEASONAL PRICING PLAN ON SEASONAL PRODUCTION VARIABILITY

From 1993 - 1995, Florida dairy cooperatives implemented a seasonal pricing plan in an attempt to decrease the variability in seasonal production. Farmers that participated in the seasonal pricing plan were able to reduce seasonality in each year when compared to 1992 by as much as 20 percent. For farmers that did not participate, seasonality increased in each year by as much as 32 percent. Overall, the seasonal pricing plan was effective in reducing seasonality for those farmers that chose to participate in the plan and that its limited short-run success was the result of seasonality increases by non-participating farms.amplitude, seasonal pricing plan, seasonality, Livestock Production/Industries,

Seasonality of birth in nineteenth and twentieth century Austria: steps toward a unified theory of human reproductive seasonality

We present an analysis of birth seasonality in nine geographical regions within Austria for two time periods, 1881-1912 and 1947-1959. In the early period, geography, climate, and agricultural patterns were related to birth seasonality. By the later time period, these factors were no longer related to birth seasonality. We propose a “resilience hypothesis,” which suggests two levels of causal influences on birth seasonality. First, underlying the three significant features of birth seasonality patterns around the world are only a small number of major causes. But, second, there are a multiplicity of minor causes that result in small perturbations in the patterns.(AUTHORS)

Descriptive Seasonal Adjustment by Minimizing Perturbations

The seasonal adjustment method proposed by Schlicht (1981) can be viewed as a method that minimizes non-stochastic deviations (perturbations). This interpretation gives rise to a critique of the seasonality criterion used there. A new seasonality criterion is proposed that avoids these shortcomings, and the resulting seasonal adjustment method is givenseasonal adjustment; seasonality; smoothing; spline; descriptive decomposition

Descriptive Seasonal Adjustment by Minimizing Perturbations

The seasonal adjustment method proposed by Schlicht (1981) can be viewed as a method that minimizes non-stochastic deviations (perturbations). This interpretation gives rise to a critique of the seasonality criterion used there. A new seasonality criterion is proposed that avoids these shortcomings, and the resulting seasonal adjustment method is give