Magnetic fields in circumstellar disks: The potential of Zeeman observations

Context. Recent high angular resolution polarimetric continuum observations of circumstellar disks provide new insights into their magnetic field. However, direct constraints are limited to the plane of sky component of the magnetic field. Observations of Zeeman split spectral lines are a potential approach to enhance these insights by providing complementary information. Aims. We investigate which constraints for magnetic fields in circumstellar disks can be obtained from Zeeman observations of the $113~\mathrm{GHz}$ CN lines. Furthermore, we analyze the requirements to perform these observations and their dependence on selected quantities. Methods. We simulate the Zeeman splitting with the radiative transfer (RT) code POLARIS (Reissl et al. 2016) extended by our Zeeman splitting RT extension ZRAD (Brauer et al. 2017), which is based on the line RT code Mol3D (Ober et al. 2015). Results. We find that Zeeman observations of the $113~\mathrm{GHz}$ CN lines provide significant insights into the magnetic field of circumstellar disks. However, with the capabilities of recent and upcoming instrument/observatories, even spatially unresolved observations would be challenging. Nevertheless, these observations are feasible for the most massive disks with a strong magnetic field and high abundance of CN/H. The most restrictive quantity is the magnetic field strength, which should be at least in the order of $\sim1~\mathrm{mG}$. In addition, the inclination of the disk should be around $60\deg$ to preserve the ability to derive the line-of-sight (LOS) magnetic field strength and to obtain a sufficiently high circularly polarized flux.Comment: 15 pages, 14 figure

High phosphate content significantly increases apatite formation of fluoride-containing bioactive glasses

NOTICE: this is the author’s version of a work that was accepted for publication in Acta Biomaterialia. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Acta Biomaterialia, [VOL 7, ISSUE 4, (2001)] DOI: 10.1016/j.actbio.2010.11.03

Universal deformation rings and generalized quaternion defect groups

We determine the universal deformation ring R(G,V) of certain mod 2 representations V of a finite group G which belong to a 2-modular block of G whose defect groups are isomorphic to a generalized quaternion group D. We show that for these V, a question raised by the author and Chinburg concerning the relation of R(G,V) to D has an affirmative answer. We also show that R(G,V) is a complete intersection even though R(G/N,V) need not be for certain normal subgroups N of G which act trivially on V.Comment: 20 pages, 6 figures. The paper has been updated as follows: The results remain true for more general 2-modular blocks with generalized quaternion defect groups (see the introduction and Hypothesis 3.1). Sections 4 and 5 have been swapped

Transcriptional regulation of the porcine type II GnRH receptor gene

The classical mammalian form of gonadotropin releasing hormone (GnRH), GnRH I, is a hypothalamic neuropeptide that functions as a key regulator of reproduction. The interaction between GnRH I and its receptor, GnRH receptor I (GnRHR I), stimulates gonadotropin secretion from the anterior pituitary gland. The gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), act on the gonads to stimulate either steroidogenesis and ovulation or gametogenesis, respectively. The steroid hormones produced in the gonads act through a feedback pathway to regulate the production of both GnRH I from the hypothalamus and gonadotropins from the anterior pituitary. Another form of GnRH, GnRH II, has recently been discovered. This isoform differs from GnRH I by 3 amino acids and is highly conserved from bony fish to man (Neill, 2001). Like GnRH I, the GnRH II ligand has been implicated in reproduction. In the rhesus monkey, GnRH II can induce LH and FSH production (Densmore and Urbanski, 2003). Furthermore, administration of GnRH II to mice and musk shrews resulted in rescued reproductive behavior in nutritionally deprived females, demonstrating that GnRH II is correlated with energy balance and reproduction in females (Kauffman et al., 2004; 2006). In male reproduction, GnRH II is involved in steroidogenesis as GnRH II agonist treatment of murine Leydig cells increased testosterone production and expression of the steroidogenic enzymes, steroidogenic acute regulatory protein (StAR), P450c and 3β-hydroxysteroid dehydrogenase (3β-HSD; Lin et al., 2008). Also, boars immunized against GnRH II had decreased gonadotropin secretion and the Leydig cells had reduced ability to respond to LH challenges, indicative of a role in both gonadotropin release and Leydig cell function (Bowen et al., 2006)

Human activity modeling and Barabasi's queueing systems

It has been shown by A.-L. Barabasi that the priority based scheduling rules in single stage queuing systems (QS) generates fat tail behavior for the tasks waiting time distributions (WTD). Such fat tails are due to the waiting times of very low priority tasks which stay unserved almost forever as the task priority indices (PI) are "frozen in time" (i.e. a task priority is assigned once for all to each incoming task). Relaxing the "frozen in time" assumption, this paper studies the new dynamic behavior expected when the priority of each incoming tasks is time-dependent (i.e. "aging mechanisms" are allowed). For two class of models, namely 1) a population type model with an age structure and 2) a QS with deadlines assigned to the incoming tasks which is operated under the "earliest-deadline-first" policy, we are able to analytically extract some relevant characteristics of the the tasks waiting time distribution. As the aging mechanism ultimately assign high priority to any long waiting tasks, fat tails in the WTD cannot find their origin in the scheduling rule alone thus showing a fundamental difference between the present and the A.-L. Barabasi's class of models.Comment: 16 pages, 2 figure

We Chinese

“We Chinese” grew out of a curiosity to find out what Chinese people think about their country and their future. Media coverage of the country and its development often raises questions about the direction of the government in Beijing on the world stage. Few reports take into account the feelings of the Chinese people, instead making reference to the country as a monolithic actor without constituent parts. A country’s trajectory through history cannot be mapped without careful consideration of the people. This project aims, in a small way, to develop a portrait of the country by looking at the individual people that make it up