In this paper we propose a new set of multivariate stochastic models that capture time varying seasonality within the vector innovations structural time series (VISTS) framework. These models encapsulate exponential smoothing methods in a multivariate setting. The models considered are the local level, local trend and damped trend VISTS models with an additive multivariate seasonal component. W...

Environmental factors affecting the species composition of periphytic diatom assemblages were analyzed in the partly polluted Asa River, in Tokyo, Japan, using principal component analysis, individual differences scaling and direct gradient analy sis. The effects of water pollution, seasonal change of temperature, and substrate were detected, among which pollution was the most influential in th...

The seasonal dynamics of cyanobacterial and diatom assemblages in 11 water bodies along a mesoto hypertrophic gradient were compared. The cyanobacterial and diatom communities are characterised according to representative species of each algal class, selected by data reduction following principal component analyses and discriminant analysis. The cyanobacterial and diatom assemblages of the four...

pycnocycla spinosa aerial parts were collected weekly during four-month growth. hydrodistillation and gas chromatography coupled with mass spectroscopy techniques were used for essential oil and sesquiterpenes investigation. thirty-four components were identified, of which the characteristic sesquiterpenes were a -copaene, caryophyllene, a -humulene, b-ionene, d-cadinene, a -calacorene, caryoph...

b a ckground: the present study aimed to demonstrate the seasonal activities of ixodes ricinus at the pasture level and on the host. m e t hods: a vast pasture in amol countryside (mazandaran province, iran) which had the potential for a considera- ble number of cattle and sheep to graze was chosen. tick sampling from the skin of 130 cattle and 130 sheep were collected every month interval. sim...

Soil moisture memory is a key component of seasonal predictability. However, uncertainty in current memory estimates is not clear and it is not obvious to what extent these are dependent on model uncertainties. To address this question, we perform a global sensitivity analysis of memory to key hydraulic parameters, using an uncoupled version of the H-TESSEL land surface model. Results show sign...

Diatoms constitute an important component of the fouling community. Although a lot of work has dealt with the fouling diatom community structure, work on the species interactions within the community is still meagre. In this regard, a study was carried out by transferring natural diatom biofilms into controlled conditions in order to understand the roles of nutrients, initial cell inoculum and ...

A component model for the analysis of financial durations is proposed. The components are the long-run dynamics and the seasonality. The later is left unspecified and the former is assumed to fall within the class of certain family of parametric functions. The joint model is estimated by maximizing a (local) quasi-likelihood function, and the resulting nonparametric estimator of the seasonal cu...

Misalignment between the timing of sleep and the circadian pacemaker has been linked to depression symptoms. This study sought to extend earlier findings by comparing sleep and circadian markers in healthy controls and individuals with major depression. Two markers of circadian misalignment correlated with depression severity in the depressed group.

Thunderstorms are convective systems characterised by the occurrence of lightning. Lightning and thunderstorm activity has been increasingly studied in recent years in relation to the El Niño/Southern Oscillation (ENSO) and various other large-scale modes of atmospheric and oceanic variability. Large-scale modes of variability can sometimes be predictable several months in advance, suggesting p...