Proper Motions in the Andromeda Subgroup

This article presents results of VLBI observations of regions of H2O maser activity in the Local Group galaxies M33 and IC10. Since all position measurements were made relative to extragalactic background sources, the proper motions of the two galaxies could be measured. For M33, this provides this galaxy's three dimensional velocity, showing that this galaxy is moving with a velocity of 190 +/- 59 km\s relative to the Milky Way. For IC10, we obtain a motion of 215 +/- 42 km/s relative to the Milky Way. These measurements promise a new handle on dynamical models for the Local Group and the mass and dark matter halo of Andromeda and the Milky Way.Comment: 4 pages 1 figures, to appear in the proceedings of "Galaxies in the Local Volume", Astrophysics and Space Science, editors B. Koribalski and H. Jerjen also available at http://www.mpifr-bonn.mpg.de/staff/abrunthaler/pub.shtm

A one-shot deviation principle for stability in matching problems

This paper considers marriage problems, roommate problems with nonempty core, and college admissions problems with responsive preferences. All stochastically stable matchings are shown to be contained in the set of matchings which are most robust to one-shot deviation

Weak spin interactions in Mott insulating La2O2Fe2OSe2

Identifying and characterizing the parent phases of iron-based superconductors is an important step towards understanding the mechanism for their high-temperature superconductivity. We present an investigation into the magnetic interactions in the Mott insulator La2O2Fe2OSe2. This iron oxyselenide adopts a 2-k magnetic structure with low levels of magnetic frustration. This magnetic ground state is found to be dominated by next-nearest-neighbor interactions J2 and J2′ and the magnetocrystalline anisotropy of the Fe2+ site, leading to 2D-Ising-like spin S=2 fluctuations. In contrast to calculations, the values are small and confine the spin excitations below ∼25 meV. This is further corroborated by sum rules of neutron scattering. This indicates that superconductivity in related materials may derive from a weakly coupled and unfrustrated magnetic structure

The gravitationally lensed, luminous infrared galaxy IRAS F10214+4724 observed with XMM-Newton

We report on a short XMM-Newton observation of the gravitationally-lensed, luminous infrared galaxy IRAS F10214+4724 at z=2.3. A faint X-ray source is detected at 4 sigma. The observed 0.5-2 keV (1.7-6.6 keV in the rest-frame) flux is 1.3e-15 erg/s/cm2 and the spectral slope in the rest-frame 1-10 keV band is Gamma~2. These results agree with those obtained from the Chandra X-ray Observatory, given the large uncertainties in both measurements. While possible evidence for excess emission above 5 keV is seen, we suspect this excess might be either spurious or not related to the infrared galaxy.Comment: 4 pages, 2 figures, New Astronomy in pres

The common ‘thermolabile' variant of methylene tetrahydrofolate reductase is a major determinant of mild hyperhomocysteinaemia

Mild hyperhomocysteinaemia is a major risk factor for vascular disease and neural tube defects (NTDs), conferring an approximately three-fold relative risk for each condition. It has several possible causes: heterozygosity for rare loss of function mutations in the genes for 5,10-methylene tetrahydrofolate reductase (MTHFR) or cystathionine-β-synthase (CBS); dietary insufficiency of vitamin co-factors B6, B12 or folates; or homozygosity for a common ‘thermolabile' mutation in the MTHFR gene which has also been associated with vascular disease and NTDs. We quantified the contribution of the thermolabile mutation to the hyperhomocysteinaemic phenotype in a working male population (625 individuals). Serum folate and vitamin B12 concentrations were also measured and their relationship with homocysteine status and MTHFR genotype assessed. The homozygous thermolabile genotype occurred in 48.4, 35.5, and 23.4% of the top 5,10, and 20% of individuals (respectively) ranked by plasma homocysteine levels, compared with a frequency of 11.5% in the study population as a whole, establishing that the mutation is a major determinant of homocysteine levels at the upper end of the range. Serum folate concentrations also varied with genotype, being lowest in thermolabile homozygotes. The MTHFR thermolabile genotype should be considered when population studies are designed to determine the effective homocysteine-lowering dose of dietary folate supplements, and when prophylactic doses of folate are recommended for individual

The Polar Bear Management Agreement for the Southern Beaufort Sea : An Evaluation of the First Ten Years of a Unique Conservation Agreement

Polar bears (Ursus maritimus) of the southern Beaufort Sea population, distributed from approximately Icy Cape, west of Point Barrow, Alaska, to Pearce Point, east of Paulatuk in Canada, are harvested by hunters from both countries. In Canada, quotas to control polar bear hunting have been in place, with periodic modifications, since 1968. In Alaska, passage of the United Sates Marine Mammal Protection Act (MMPA) of 1972 banned polar bear hunting unless done by Alaska Natives for subsistence hunt, leaving open the potential for an overharvest with no possible legal management response until the population was declared depleted. Recognizing that as a threat to the conservation of the shared polar bear population, the Inuvialuit Game Council from Canada and the North Slope Borough from Alaska negotiated and signed a user-to-user agreement, the Polar Bear Management Agreement for the Southern Beaufort Sea, in 1988. We reviewed the functioning of the agreement through its first 10 years and concluded that, overall, it has been successful because both the total harvest and the proportion of females in the harvest have been contained within sustainable limits. However, harvest monitoring needs to be improved in Alaska, and awareness of the need to prevent overharvest of females needs to be increased in both countries. This agreement is a useful model for other user-to-user conservation agreements.Les ours polaires (Ursus maritimus) constituant la population de la mer de Beaufort méridionale sont répartis d'environ Icy Cape, à l'ouest de Point Barrow (Alaska), à Pearce Point, à l'est de Paulatuk (Canada). Ils sont prélevés par des chasseurs des deux pays. Au Canada, les quotas visant le contrôle de la chasse à l'ours polaire sont en vigueur - avec des modifications périodiques - depuis 1968. En Alaska, l'adoption en 1972 de la loi américaine (MMPA) visant la protection des mammifères marins a interdit la chasse à l'ours polaire sauf la chasse de subsistance pratiquée par les Autochtones alaskiens. La MMPA n'a toutefois placé aucune restriction sur le nombre ou la composition de la chasse de subsistance, laissant la porte ouverte à une éventuelle surexploitation sans possibilité d'une réaction de gestion sur le plan légal jusqu'à ce que la population soit déclarée décimée. Reconnaissant en cela une menace à la conservation de la population commune d'ours polaires, le Conseil canadien de gestion du gibier et le North Slope Borough de l'Alaska ont négocié et signé en 1988 une entente entre usagers, le Polar Bear Management Agreement pour la mer de Beaufort méridionale. On a examiné le fonctionnement de l'entente durant sa première décennie pour conclure que, dans l'ensemble, elle a porté fruit car le total des prises et la proportion de femelles prélevées ont été maintenus dans des limites viables. Il faut toutefois améliorer le contrôle du prélèvement en Alaska et accroître dans les deux pays la sensibilisation à la nécessité de prévenir une surexploitation des femelles. Cette entente constitue un modèle pour d'autres accords entre usagers en matière de conservation

Non-equilibrium states of a photon cavity pumped by an atomic beam

We consider a beam of two-level randomly excited atoms that pass one-by-one through a one-mode cavity. We show that in the case of an ideal cavity, i.e. no leaking of photons from the cavity, the pumping by the beam leads to an unlimited increase in the photon number in the cavity. We derive an expression for the mean photon number for all times. Taking into account leaking of the cavity, we prove that the mean photon number in the cavity stabilizes in time. The limiting state of the cavity in this case exists and it is independent of the initial state. We calculate the characteristic functional of this non-quasi-free non-equilibrium state. We also calculate the energy flux in both the ideal and open cavity and the entropy production for the ideal cavity.Comment: Corrected energy production calculations and made some changes to ease the readin

Dynamical percolation on general trees

H\"aggstr\"om, Peres, and Steif (1997) have introduced a dynamical version of percolation on a graph $G$. When $G$ is a tree they derived a necessary and sufficient condition for percolation to exist at some time $t$. In the case that $G$ is a spherically symmetric tree, H\"aggstr\"om, Peres, and Steif (1997) derived a necessary and sufficient condition for percolation to exist at some time $t$ in a given target set $D$. The main result of the present paper is a necessary and sufficient condition for the existence of percolation, at some time $t\in D$, in the case that the underlying tree is not necessary spherically symmetric. This answers a question of Yuval Peres (personal communication). We present also a formula for the Hausdorff dimension of the set of exceptional times of percolation.Comment: 24 pages; to appear in Probability Theory and Related Field

Genetic variation at MECOM, TERT, JAK2 and HBS1L-MYB predisposes to myeloproliferative neoplasms

Clonal proliferation in myeloproliferative neoplasms (MPN) is driven by somatic mutations in JAK2, CALR or MPL, but the contribution of inherited factors is poorly characterized. Using a three-stage genome-wide association study of 3,437 MPN cases and 10,083 controls, we identify two SNPs with genome-wide significance in JAK2V617F-negative MPN: rs12339666 (JAK2; meta-analysis P=1.27 × 10−10) and rs2201862 (MECOM; meta-analysis P=1.96 × 10−9). Two additional SNPs, rs2736100 (TERT) and rs9376092 (HBS1L/MYB), achieve genome-wide significance when including JAK2V617F-positive cases. rs9376092 has a stronger effect in JAK2V617F-negative cases with CALR and/or MPL mutations (Breslow–Day P=4.5 × 10−7), whereas in JAK2V617F-positive cases rs9376092 associates with essential thrombocythemia (ET) rather than polycythemia vera (allelic χ2 P=7.3 × 10−7). Reduced MYB expression, previously linked to development of an ET-like disease in model systems, associates with rs9376092 in normal myeloid cells. These findings demonstrate that multiple germline variants predispose to MPN and link constitutional differences in MYB expression to disease phenotype

The Japanese Male-Female Wage Differentials Revisited

Contains fulltext : 139890.pdf (publisher's version ) (Open Access)Aims: Abnormal physiological stress reactivity is increasingly investigated as a vulnerability marker for various physical and psychological health problems. However, studies are inconsistent in taking into account potential covariates that may influence the developing stress system. We systematically tested determinants (individual, developmental, environmental and substance use-related) of physiological and perceived physiological stress reactivity. We also examined the relation between physiological and perceived physiological stress reactivity. Method: In a stratified sample of 363 children (7–12 years) and 344 adolescents (13–20 years) from the general population, we examined cortisol, heart rate, respiratory sinus arrhythmia and perceived physiological stress reactivity to a psychosocial stress procedure. Results: Using multivariate linear regression models, we found that individual, developmental, environmental and substance use-related factors were related to each of the stress response indices. These determinant factors were different for each of the stress reactivity indices, and different in children versus adolescents. Perceived physiological stress reactivity predicted cortisol reactivity in adolescents only. All other relations between perceived physiological and physiological stress reactivity were not significant. Conclusions: As physiological stress variables are often examined as vulnerability markers for the development of health problems, we maintain that it is essential that future studies take into consideration factors that may account for found relations. Our study provides an overview and indication of which variables should be considered in the investigation of the relation between physiological stress indices and illness.13 p