Tests for time series of counts based on the probability-generating function

We propose testing procedures for the hypothesis that a given set of discrete observations may be formulated as a particular time series of counts with a specific conditional law. The new test statistics incorporate the empirical probability-generating function computed from the observations. Special emphasis is given to the popular models of integer autoregression and Poisson autoregression. The asymptotic properties of the proposed test statistics are studied under the null hypothesis as well as under alternatives. A Monte Carlo power study on bootstrap versions of the new methods is included as well as real-data examples.     

A NOTE ON EVANESCENT PROCESSES

This note examines the connection between μ-invariant measures for the transition function of a continuous-time Markov chain and those of its q-matrix, Q. The major result establishes a necessary and aufficient condition for a convergent μ-invariant measure for Q to be μ-inhant for the minimal transition function, P, under the assumption that P is honest. This corrects Theorem 6 of Vere-Jones (1969) and the first part of Corollary 1 of Pollett (1986), both of which assert that the above conclusion holds in the absence of this condition. The error was pointed out by E.A. van Doom (1991) and the counterexample which be presented provides the basis for the present arguments. In determining where the error occurred in the original proof, we are able to identify a simple sufficient condition for μ-invariance.     

Demographic Shifts in the Czech Republic after 1989: A Second Demographic Transition View

A dramatic change in fertility,family formation and living arrangements tookplace in the Czech Republic over the 1990s. Theestablishment of democracy, profound socialtransformation and transition to the marketeconomy affected the values and demographicbehaviour of the young Czech generation. Thispaper examines whether these demographic shiftscan be interpreted within the framework of thesecond demographic transition. The theoreticalpart discusses the idea of the transition,outlining three distinctive conceptualisations.Two of them – the view of the transition as aprogression of characteristic interrelateddemographic changes and a broader viewstressing the importance of underlyingideational factors – fit the Czech situationvery well. A comparison with the Netherlandsreveals that the onset of the transition in theCzech Republic may be clearly located in thefirst half of the 1990s, lagging two decadesbehind the Netherlands.     

Multilevel maximum likelihood estimation with application to covariance matrices

The asymptotic variance of the maximum likelihood estimate is proved to decrease when the maximization is restricted to a subspace that contains the true parameter value. Maximum likelihood estimation allows a systematic fitting of covariance models to the sample, which is important in data assimilation. The hierarchical maximum likelihood approach is applied to the spectral diagonal covariance model with different parameterizations of eigenvalue decay, and to the sparse inverse covariance model with specified parameter values on different sets of nonzero entries. It is shown computationally that using smaller sets of parameters can decrease the sampling noise in high dimension substantially.     

The German East-West Mortality Difference: Two Crossovers Driven by Smoking

Before the fall of the Berlin Wall, mortality was considerably higher in the former East Germany than in West Germany. The gap narrowed rapidly after German reunification. The convergence was particularly strong for women, to the point that Eastern women aged 50–69 now have lower mortality despite lower incomes and worse overall living conditions. Prior research has shown that lower smoking rates among East German female cohorts born in the 1940s and 1950s were a major contributor to this crossover. However, after 1990, smoking behavior changed dramatically, with higher smoking intensity observed among women in the eastern part of Germany. We forecast the impact of this changing smoking behavior on East-West mortality differences and find that the higher smoking rates among younger East German cohorts will reverse their contemporary mortality advantage. Mortality forecasting methods that do not account for smoking would, perhaps misleadingly, forecast a growing mortality advantage for East German women. Experience from other countries shows that smoking can be effectively reduced by strict anti-smoking policies. Instead, East Germany is becoming an example warning of the consequences of weakening anti-smoking policies and changing behavioral norms.     

Self-Stigma of seeking help and job burnout in mental health care providers: the comparative study of Lithuanian and the USA samples

This study aimed to explore the correlation between job burnout and self-stigma of seeking help among nonmedical mental health care providers (psychologists, social workers, and counselors) in two countries – Lithuania and the US. The study included 234 professionals (111 social workers and 123 psychologists) from Lithuania and 93 professionals (33 counselors, 23 social workers, and 37 psychologists) from the US on a voluntary basis (93% females, mean age – 39.81?years). They completed a self-reported questionnaire with the Self-Stigma of Seeking Help Scale (SSOSH) and the Maslach Burnout Inventory-General Survey (MBI-GS). The results revealed a statistically significant positive correlation between self-stigmatization and burnout in the Lithuanian sample, but only weak positive correlation between depersonalization and self-stigma of seeking help in the US sample. The relationship between the self-stigma of seeking help and burnout was stronger in the Lithuanian sample of professionals when compared to their colleagues in the US.     

The impact of testosterone replacement therapy on glycemic control,vascular function,and components of the metabolic syndrome in obese hypogonadal men with type 2 diabetes

Objective: This study set out to assess effects of testosterone replacement therapy (TRT) on parameters of metabolic syndrome and vascular function in obese hypogonadal males with type 2 diabetes mellitus (DM2).

Study design: Fifty-five obese hypogonadal diabetic males on oral hypoglycemic treatment were enrolled into this one-year, double-blind, randomized, placebo-controlled clinical study. Group T (n?=?28) was treated with testosterone undecanoate (1000?mg i.m. every 10?weeks) while group P (n?=?27) received placebo.

Methods: Anthropometrical and vascular measurements – flow-mediated dilatation (FMD) and intima media thickness (IMT) – biochemical and hormonal blood sample analyses were performed at the start of the study and after one year. Derived parameters (BMI, HOMA-IR, calculated free testosterone (cFT) and bioavailable testosterone (BT)) were calculated.

Results: TRT resulted in reduction of HOMA-IR by 4.64?±?4.25 (p?p?p?=?.005).

Conclusion: TRT normalized serum testosterone levels, improved glycemic control and endothelial function while exerting no ill effects on the study population.     

Threatened plant species in the river ports of Central Europe: a potential for nature conservation

Industrialized areas represent a special group of urbanized areas, but sufficient attention has not been given to them concerning plant species richness and its importance for biodiversity conservation. These sites are considered the main drivers of biological invasions and biotic homogenization on a global scale, but the question of how and to what degree they contribute to biodiversity has yet to be raised. Data for 62 river ports (16 German, 26 Czech, 7 Hungarian, 4 Slovak, and 9 Austrian) on two important Central European waterways (the Elbe-Vltava and Danube waterways) were gathered for 40 years. In total, 1 240 plant species were found. Of these, 371 were classified as threatened and protected, nearly one third of the total number of species found in all of the studied Elbe, Vltava, and Danube ports. Significant differences in the proportion of threatened species in ports and cities were not found. More threatened species were found in the Danube ports than in the other ports, but their numbers fluctuated depending on the size of the port and the region (country). The results showed that the ports must be regarded as special types of species-rich industrial areas; thus, they should not be considered to be only sources of spreading invasive alien species. When planning port development, uniformity and vegetation management that is too intensive should be avoided. Extensively managed open areas and habitat diversity should be maintained.