Statistical methods for detecting and comparing periodic data and their application to the nycthemeral rhythm of bodily harm: A population based study.

BACKGROUND: Animals, including humans, exhibit a variety of biological rhythms. This article describes a method for the detection and simultaneous comparison of multiple nycthemeral rhythms. METHODS: A statistical method for detecting periodic patterns in time-related data via harmonic regression is described. The method is particularly capable of detecting nycthemeral rhythms in medical data. Additionally a method for simultaneously comparing two or more periodic patterns is described, which derives from the analysis of variance (ANOVA). This method statistically confirms or rejects equality of periodic patterns. Mathematical descriptions of the detecting method and the comparing method are displayed. RESULTS: Nycthemeral rhythms of incidents of bodily harm in Middle Franconia are analyzed in order to demonstrate both methods. Every day of the week showed a significant nycthemeral rhythm of bodily harm. These seven patterns of the week were compared to each other revealing only two different nycthemeral rhythms, one for Friday and Saturday and one for the other weekdays.

iPad-assisted measurements of duration estimation in psychiatric patients and healthy control subjects.

Handheld devices with touchscreen controls have become widespread in the general population. In this study, we examined the duration estimates (explicit timing) made by patients in a major general hospital and healthy control subjects using a custom iPad application. We methodically assessed duration estimates using this novel device. We found that both psychiatric and non-psychiatric patients significantly overestimated time periods compared with healthy control subjects, who estimated elapsed time very precisely. The use of touchscreen-based methodologies can provide valuable information about patients.

Somnography using unobtrusive motion sensors and Android-based mobile phones.

Sleep plays a fundamental role in the life of every human. The prevalence of sleep disorders has increased significantly, now affecting up to 50% of the general population. Sleep is usually analyzed by extracting a hypnogram containing sleep stages. The gold standard method polysomnography (PSG) requires subjects to stay overnight in a sleep laboratory and to wear a series of obtrusive devices. This work presents an easy to use method to perform somnography at home using unobtrusive motion sensors. Ten healthy male subjects were recorded during two consecutive nights. Sensors from the Shimmer platform were placed in the bed to record accelerometer data, while reference hypnograms were collected using a SOMNOwatch system. A series of filters were used to extract a motion feature in 30 second epochs from the accelerometer signals. The feature was used together with the ground truth information to train a Naive Bayes classifiers that distinguished wakefulness, REM and non-REM sleep. Additionally the algorithm was implemented on an Android mobile phone. Averaged over all subjects, the classifier had a mean accuracy of 79.0 % (SD 9.2%) for the three classes. The mobile phone implementation was able to run in realtime during all experiments. In future this will lead to a method for simple and unobtrusive somnography using mobile phones.

Assaults in the elderly--a population-based study with victim and perpetrator characteristics.

The aim of the present epidemiological study was to investigate characteristics of assaults in the elderly aged 65 years and above from the perspective of the victim and perpetrator. This population-based study included 23,142 assaults (according to §§ 224/226 StGB of German criminal law) that were recorded in Bavaria, Germany, from 1999 to 2005. The population-based ratio of serious crimes of battery for the elderly in comparison with the reference population was markedly lower (0.10; 95% CI: 0.09-0.11) in suspects aged more than 65 years and 0.08 (95% CI: 0.07-0.09) for the injured above 65 years. Elderly perpetrators differed significantly concerning the manner of the assault (p < 0.001). They committed less crimes in urban areas (56.1% vs. 68.8%) and were victimized significantly more in rural areas (p < 0.001; 41.2% vs. 30.2%). Violence in the elderly differs from that of the younger population. Further research is warranted to establish prevention measures.