On the Bergman representative coordinates

We study the set where the so-called Bergman representative coordinates (or Bergman functions) form an immersion. We provide an estimate of the size of a maximal geodesic ball with respect to the Bergman metric, contained in this set. By concrete examples we show that these estimates are the best possible.Comment: 20 page

Human model MATROSHKA for radiation exposure determination of astronauts

The exploration of space as seen in specific projects from the European Space Agency (ESA) acts as groundwork for human long-duration space missions. One of the main constraints for long-duration human missions is radiation. The radiation load on space travellers is a factor of ~100 higher than the natural radiation exposure on Earth and it might further increase due to solar particle events should humans travel to Mars. In preparation for long-duration space missions, it is important to evaluate the impact of space radiation in order to secure the safety of astronauts and minimize their radiation risks. To determine the radiation risks on humans one has to measure the radiation doses to vital organs of the human body. One way to realize this is the utilization of the ESA facility MATROSHKA (MTR), which houses a human phantom and is operated under the scientific project lead of the German Aerospace Center (DLR). The facility was launched in January 2004 and is just performing its fourth experimental phase - now inside the Japanese Experiment Module (JEM). The MATROSHKA project is dedicated determining the radiation load on astronauts when staying within or outside the International Space Station (ISS). The MTR phantom is equipped with over 6,000 radiation detectors to determine the depth dose and organ dose distribution in the body. It is the largest international research initiative ever performed in the field of space dosimetry and combines the expertise of leading research institutions around the world, thereby generating a huge pool of data of potentially immense value for research. Aiming at optimal scientific exploitation, the FP7 project HAMLET intends to process and compile the data acquired individually by the participating laboratories of the MATROSHKA experiment. Based on experimental input from the MATROSHKA experiment phases as well as radiation transport calculations, a three-dimensional model for the distribution of radiation dose in an astronaut´s body will be set up. Based on a solid experimental and theoretical basis the model is essential for realistic radiation risk estimates for future human interplanetary space exploration. Data received up to now from the MTR experimental phases (MTR-1, -2A and -2B) are already implemented in the database along with relevant experimental and scientific background data. DOI: 10.2769/154

Ritual and Communication in the Graeco-Roman World

The analysis of the dynamic nature of rituals has become a heuristic tool for the investigation not only of religious behaviour and beliefs, but also for the study of social practice and communication in ancient and modern societies. From public assembly gatherings and funerals to celebration of cult feasts or the honouring of individuals, rituals mark socially important occasions, define beginnings and endings, and aid social transitions. Thus, rituals carry all kinds of messages intended to support and express the performance of those involved, and to create the desired results. The present volume brings together a collection of articles on rituals in the Graeco-Roman world, focussing on the interconnection between ritual as a means of communication and communication as a ritual phenomenon. In regarding rituals as an interface in the realm of cultural practices, the contributors demonstrate the manifold function of ritual communication in the life of ancient communities

Prolactin-releasing peptide contributes to stress-related mood disorders and inhibits sleep/mood regulatory melanin-concentrating hormone neurons in rats

Stress disorders impair sleep, quality of life, however, their pathomechanisms are unknown. Prolactin-releasing peptide (PrRP) is a stress mediator, therefore, we hypothesised that PrRP may be involved in the development of stress disorders. PrRP is produced by the medullary A1/A2 noradrenaline (NA) cells, which transmit stress signals to forebrain centers, and by non-NA cells in the hypothalamic dorsomedial nucleus. We found in male rats that both PrRP and PrRP-NA cells innervate melanin-concentrating hormone (MCH) producing neurons in the dorsolateral hypothalamus (DLH). These cells serve as a key hub for regulating sleep and affective states. Ex vivo, PrRP hyperpolarized MCH neurons and further increased the hyperpolarization caused by NA. Following sleep deprivation, intracerebroventricular PrRP injection reduced the number of REM sleep-active MCH cells. PrRP expression in the dorsomedial nucleus was up-regulated by sleep deprivation, while down-regulated by REM sleep rebound. Both in learned helplessness paradigm and after peripheral inflammation, impaired coping with sustained stress was associated with (i) overactivation of PrRP cells, (ii) PrRP protein and receptor depletion in the DLH, and (iii) dysregulation of MCH expression. Exposure to stress in PrRP insensitive period led to increased passive coping with stress. Normal PrRP signaling, therefore, seems to protect animals against stress-related disorders. PrRP signaling in the DLH is important component of the PrRP's action, which may be mediated by MCH neurons. Moreover, PrRP receptors were downregulated in the DLH of human suicidal victims. As stress-related mental disorders are the leading cause of suicide, our findings may have particular translational relevance.SIGNIFICANCE STATEMENT:Treatment resistance to monoaminergic antidepressants is a major problem. Neuropeptides that modulate the central monoaminergic signaling are promising targets for developing alternative therapeutic strategies. We found that stress-responsive prolactin-releasing peptide (PrRP) cells innervated melanin-concentrating hormone (MCH) neurons that are crucial in the regulation of sleep and mood. PrRP inhibited MCH cell activity and enhanced the inhibitory effect evoked by noradrenaline, a classic monoamine, on MCH neurons. We observed that impaired PrRP signaling led to failure in coping with chronic/repeated stress and was associated with altered MCH expression. We found alterations of the PrRP system also in suicidal human subjects. PrRP dysfunction may underlie stress disorders, and fine-tuning MCH activity by PrRP may be an important part of the mechanism