We investigate the scaling properties of the primary flow modes and their sensitivity to aspect ratio in a liquid gallium (Prandtl number $Pr = 0.02$) convection system through combined laboratory experiments and numerical simulations. We survey cylindrical aspect ratios $1.4 \le \varGamma \le 3$ and Rayleigh numbers $10^{4} \lesssim Ra \lesssim 10^{6}$. In this range the flow is dominated by a large-scale circulation (LSC) subject to low-frequency oscillations. In line with previous studies, we show robust scaling of the Reynolds number $Re$ with $Ra$ and we confirm that the LSC flow is dominated by a jump-rope vortex (JRV) mode whose signature frequency is present in velocity and temperature measurements. We further show that both $Re$ and JRV frequency scaling trends are relatively insensitive to container geometry. The temperature and velocity spectra consistently show peaks at the JRV frequency, its harmonic and a secondary mode. The relative strength of these peaks changes and the presence of the secondary peak depend highly on aspect ratio, indicating that, despite having a minimal effect on typical velocities and frequencies, the aspect ratio has a significant effect on the underlying dynamics. Applying a bandpass filter at the secondary frequency to velocity measurements reveals that a clockwise twist in the upper half of the fluid layer coincides with a counterclockwise twist in the bottom half, indicating a torsional mode. For aspect ratio $\varGamma = 3$, the unified LSC structure breaks down into multiple rolls in both simulation and experiment.

Although genetic and environmental factors operating before or around the time of birth have been demonstrated to be relevant to the aetiology of the major psychoses, a seasonal variation in the rates of admission of such patients has long been recognised. Few studies have compared first and readmissions. This study examined for seasonal variation of admission in the major psychoses, and compared diagnostic categories by admission status. Patients admitted to Irish psychiatric inpatient facilities between 1989 and 1994 with an ICD-9/10 diagnosis of schizophrenia or affective disorder were identified from the National Psychiatric Inpatient Reporting System (NPIRS). The data were analysed using a hierarchical log linear model, the chi-square test, a Kolmogorov-Smirnov (KS) type statistic, and the method of Walter and Elwood. The hierarchical log linear model demonstrated significant interactions between the month of admission and admission order (change in scaled deviance 28.77, df = 11, P < 0.003). Both first admissions with mania, and readmissions with bipolar affective disorder exhibited significant seasonality. In contrast, only first admissions with schizophrenia showed significant seasonal effects. Although first admissions with mania and readmissions with bipolar disorder both show seasonality, seasonal influences appear to be more relevant to onset of schizophrenia than subsequent relapse.

Seasonal variation in the births of patients with schizophrenia is a consistently replicated epidemiological finding. Few studies have investigated this phenomenon among patients with a diagnosis of affective disorder. The majority of season of birth studies have employed the chi square test for statistical analysis, a method that has been subject to some criticism. Using a Kolgomorov-Smirnov type statistic, the quarterly birth distribution of 6,646 patients with an ICD 9/10 diagnosis of affective disorder were compared to the general population. Only the births of those individuals with unipolar forms of affective disorder (n = 4,393) differed significantly from the general population, with significant excesses and deficits in the second quarter and fourth quarter respectively. These results were not altered by application of the displacement test. © 1998 Elsevier, Paris