Cell polarity under extreme morphological conditions

Cell polarity is an important phenomenon in a multitude of cellular and developmental processes. The cellular contexts that polarity occurs in include a wide array of morphological properties such as size, shape, and growth. An important, conserved system of cell polarity depends on the intracellular localisation of proteins that act as diffusive molecular switches. Since the localisation of these proteins depends on their reactive and diffusive properties, cell size and growth may alter polarity induced by localisation. My work contributes extensive analyses of an established protein localisation model under extreme morphological conditions such as extremely small and rapidly growing cells. My work also uncovers non-trivial, biologically relevant behaviour caused by the inclusion of these morphological properties and further discusses the mechanisms underlying the observed behaviour. In addition, I contribute and discuss a novel computational tool that can continue to aid the research community in understanding cell polarity under extreme morphological conditions

Measuring irreversible dynamics of a quantum harmonic oscillator

We show that the unitary evolution of a harmonic oscillator coupled to a two-level system can be undone by a suitable manipulation of the two-level system -- more specifically: by a quasi-instantaneous phase change. This enables us to isolate the dissipative evolution to which the oscillator may be exposed in addition. With this method we study the decoherence of a photon mode in cavity QED, and that of the quantized harmonic motion of trapped ions. We comment on the relation to spin echoes and multi-path interferometry.Comment: 4 pages, 2 figures; submitted to Physical Review A as a Rapid Communicatio

On mechanisms that enforce complementarity

In a recent publication Luis and Sanchez-Soto arrive at the conclusion that complementarity is universally enforced by random classical phase kicks. We disagree. One could just as well argue that quantum entanglement is the universal mechanism. Both claims of universality are unjustified, however.Comment: 4 page

Fukushima-derived radionuclides in sediments of the Japanese Pacific Ocean coast and various Japanese water samples (seawater, tap water, and coolant water of Fukushima Daiichi reactor unit 5)

We investigated Ocean sediments and seawater from inside the Fukushima exclusion zone and found radiocesium (134Cs and 137Cs) up to 800 Bq kg-1 as well as 90Sr up to 5.6 Bq kg-1. This is one of the first reports on radiostrontium in sea sediments from the Fukushima exclusion zone. Seawater exhibited contamination levels up to 5.3 Bq kg-1 radiocesium. Tap water from Tokyo from weeks after the accident exhibited detectable but harmless activities of radiocesium (well below the regulatory limit). Analysis of the Unit 5 reactor coolant (finding only 3H and even low 129I) leads to the conclusion that the purification techniques for reactor coolant employed at Fukushima Daiichi are very effective.JSPS KAKENHI/25870158CDC NIOSH Mountain and Plains Education and Research Center/T42OH009229-07NRC/NRC-HQ-12-G-38-004

Kiri tundmatule, Weissenfels

http://tartu.ester.ee/record=b1901622~S6*es

Acquired heart block: A possible complication of patent ductus arteriosus in a preterm infant

A large patent ductus arteriosus (PDA) is a frequently encountered clinical problem in extremely low birth weight (ELBW) infants. It leads to an increased pulmonary blood flow and in a decreased or reversed diastolic flow in the systemic circulation, resulting in complications. Here we report a possible complication of PDA not previously published. On day 8 of life, a male ELBW infant (birth weight 650 g) born at a gestational age of 23 weeks and 3 days developed an atrioventricular block (AV block). The heart rate dropped from 168/min to 90/min, and the ECG showed a Wenckebach second-degree AV block and intraventricular conduction disturbances. Echocardiography demonstrated a PDA with a large left-to-right shunt and large left atrium and left ventricle with high contractility. Within several minutes after surgical closure of the PDA, the heart rate increased, and after 30 min the AV block had improved to a 1: 1 conduction ratio. Echocardiography after 2 h revealed a significant decrease of the left ventricular and atrial dimensions. Within 12 h, the AV block completely reversed together with the intraventricular conduction disturbances. We suggest that PDA with a large left-to-right shunt and left ventricular volume overload may lead to an AV block in an ELBW infant. Surgical closure of the PDA may be indicated. Copyright (C) 2007 S. Karger AG, Basel

The eruptive history of the Trous Blancs pit craters, La Réunion Island: The origin of a 24 km long lava flow

International audienceThe assessment of volcanic hazards is strongly based on the past eruptive behaviour of volcanoes and its morphological parameters. Since past eruption characteristics and their frequency provide the best probabilities of such eruptions for the future, understanding the complete eruptive history of a volcano is one of the most powerful tools in assessing the potential hazards or eruptions. At Piton de la Fournaise (PdF) volcano (La Réunion, Indian Ocean), the most frequent style of activity is the effusion of lava flows, which pose the greatest hazard by invasion of inhabited areas and destruction of human property. Here we examined the eruptive history of a previously uninvestigated area, believed to be the origin of a 24 km long lava flow.The eruptions recurrence time of PdF is about one eruption every 9 months in the central caldera. Besides this central activity, eruptive vents have been built along three main rift zones cutting the edifice during the last 50 kyrs. In this study we focused on the largest rift zone of about 15 km width and 20 km length, which extends in a north westerly direction between PdF and the nearby Piton des Neiges volcanic complex. This rift zone is typified by deep seismicity (up to 30 km), emitting mostly primitive magmas, indicative of high fluid pressures (up to 5 kbar) and large volume eruptions. Our area of investigation focused on four consecutively aligned pit craters called the Trous Blancs. These have been identified [1] as the source area of one of the youngest (ca. 6 kyrs) and largest lava field, which extends for 24 km from a height of 1800m asl, passing Le Tampon and Saint Pierre city, until it reaches the coast. To gain insight into the development of this eruption and possible future similar activity, we collected new field data (including stratigraphic logs, a geological map of the area, C-14 dating and geochemical analyses of the eruptive products).Fieldwork revealed that the eruption initiated with intense fountaining activity, producing a m-thick bed of loose black scoria, which becomes densely welded in its upper part. It was followed by an alternation of volume rich lava effusions and strombolian activity and deposition of meter-thick massive units of olivine basalt, alternating with coarse scoria beds in the proximal area. Activity ended with the emplacement of a dm sized bed of glassy, dense scoria and a stratified lithic breccia, marking the pit crater formation.Preliminary dating suggested that this type of eruption could have a millennial recurrence time at PdF. Reoccurring similar activity on the NW rift represents a major source of risk for this now densely populated region (more than 150,000 people living in the affected area)

On the Geometry of Spherical Trochoids

U ovom radu se proučavaju tlocrti sfernih trohoida pomoću sintetičke metode. Pokazuje se da su te projekcije više trohoide, tj. krivulje nastale istovremenim djelovanjem više od dvije rotacije. Posebni oblici ovih trohoida pojavljuju se u slučajevima posebnih odabira sfernih polumjera kružnica koje se kotrljaju. Prikazana je veza sa zatvorenim algebarskim krivuljama konstantne širine. Ove krivulje dopuštaju kinematičko izvođenje.We provide a synthetic study of the top-views of spherical trochoids. These projections turn out to be higher trochoids, i.e., curves generated by the superposition of more than two rotations. Special shapes of these trochoids show up for special choices of the spherical radii of the rolling circles. A relation to closed algebraic curves of constant width is shown. These curves allow for a kinematic generation

Mindfulness-Based Student Training Improves Vascular Variability Associated With Sustained Reductions in Physiological Stress Response

In today's fast-paced society, chronic stress has become an increasing problem, as it can lead to psycho-physiological health problems. University students are also faced with stress due to the demands of many courses and exams. The positive effects of mindfulness-based stress reduction (MBSR) on stress management and self-regulation have already been studied. We have developed a new mindfulness intervention tailored for students—the Mindfulness-Based Student Training (MBST). In this study, we present longitudinal results of the MBST evaluation. Biosignal analysis methods, including pulse wave variability (PWV), heart rate variability, and respiratory activity, were used to assess participants' state of autonomic regulation during the 12-week intervention and at follow-up. The progress of the intervention group (IGR, N = 31) up to 3 months after the end of MBST was compared with that of a control group (CON , N = 34). In addition, the long-term effect for IGR up to 1 year after intervention was examined. The analysis showed significant positive changes in PWV exclusively for IGR. This positive effect, particularly on vascular function, persists 1 year after the end of MBST. These results suggest a physiologically reduced stress level in MBST participants and a beneficial preventive health care program for University students