2,006 research outputs found
Impact of Gene-Gender Effects of Adrenergic Polymorphisms on Hypothalamic-Pituitary-Adrenal Axis Activity in Depressed Patients
Objective: There is overwhelming evidence that activation of the hypothalamic-pituitary-adrenal (HPA) system plays a major role in depression and cardiovascular disease in genetically susceptible individuals. We hypothesized that due to the multiple interactions between the sympathetic and the HPA systems via adrenoceptors, polymorphisms in these genes could have an impact on HPA axis activity in major depression. Methods: Using the dexamethasone/corticotrophin-releasing hormone (DEX/CRH) test, we investigated the association of alpha 2-adrenoceptor (ADRA2A -1291C -> G) and the beta 2-adrenoceptor gene (ADRB2 Arg16Gly) in 189 patients with major depression during the acute state of the disease and after remission. Results: Male ADRA2A -1291G allele homozygotes showed significant pretreatment HPA axis hyperactivity, with increased adrenocorticotropin (ACTH; F = 4.9, d.f. = 2, p = 0.009) and cortisol responses (F = 6.4, d.f. = 2, p = 0.003). In contrast, female ADRB2 Arg/Arg homozygotes had increased pretreatment ACTH (F = 7.17, d.f. = 2, p = 0.001) and cortisol (F = 8.95, d.f. = 2, p = 0.000) levels. Interestingly, in the respective genotypes, the stress hormones remained elevated in the second DEX/CRH test, despite a reduction in depressive symptoms. Conclusions: This study provides evidence that, depending on gender and polymorphisms, there is continuous HPA axis overdrive in a proportion of patients irrespective of the status of depression. Considering the importance of stress hormones for cardiovascular disorders, our data might suggest that these patients are at high risk of comorbidity between depression and cardiovascular disorders. Copyright (c) 2008 S. Karger AG, Base
RR Pictoris: an old nova showing superhumps and QPOs
We present time-resolved V-photometry of the old nova RR Pic. Apart from the
hump-like variability, the light curves show the strong flickering and random
variation typical for RR Pic. We do not find any convincing evidence for the
previously reported eclipse. The extrapolated eclipse phase coincides with a
broad minimum, but comparing the overall shape of the light curve suggests that
the eclipse should actually be located around phase 0.2. The orbital period
which we derive from these data agrees well with the old one, any uncertainty
is too small to account for the possible phase shift. Apart from the 3.48h
period, which is usually interpreted as the orbital one, we find an additional
period at P=3.78h, which we interpret as the superhump period of the system;
the corresponding precession period at 1.79d is also present in the data. We
also find indications for the presence of a 13min quasi-periodic oscillation.Comment: 9 pages, 7 figures + 1 Appendix figure, accepted by MNRA
Detection of a period decrease in NN Ser with ULTRACAM: evidence for strong magnetic braking or an unseen companion?
We present results of high time resolution photometry of the eclipsing
pre-cataclysmic variable NN Ser. We observed 13 primary eclipses of NN Ser
using the high-speed CCD camera ULTRACAM and derived times of mid-eclipse, from
fitting of light curve models, with uncertainties as low as 0.06 s. The
observed rates of period change appear difficult to reconcile with any models
of orbital period change. If the observed period change reflects an angular
momentum loss, the average loss rate is consistent with the loss rates (via
magnetic stellar wind braking) used in standard models of close binary
evolution, which were derived from observations of much more massive cool
stars. Observations of low-mass stars such as NN Ser's secondary predict rates
of ~100 times lower than we observe. We show that magnetic activity-driven
changes in the quadrupole moment of the secondary star (Applegate, 1992) fail
to explain the period change by an order of magnitude on energetic grounds, but
that a light travel time effect caused by the presence of a third body in a
long (~ decades) orbit around the binary could account for the observed changes
in the timings of NN Ser's mid-eclipses. We conclude that we have either
observed a genuine angular momentum loss for NN Ser, in which case our
observations pose serious difficulties for the theory of close binary
evolution, or we have detected a previously unseen low-mass companion to the
binary.Comment: 10 pages, 6 figures. Accepted for publication in MNRA
Can angular momentum loss cause the period change of NN Ser?
NN Ser is a non mass-transferring pre-cataclysmic variable containing a white
dwarf with a mass of and an M dwarf secondary star with a
mass of . Based on the data detected by the high-speed CCD
camera ULTRACAM, it was observed that the orbital period of NN Ser is
decreasing, which may be caused by a genuine angular momentum loss or the
presence of a third body. However, neither gravitational radiation and magnetic
braking can ideally account for the period change of NN Ser. In this Letter, we
attempt to examine a feasible mechanism which can drain the angular momentum
from NN Ser. We propose that a fossil circumbinary disk (CB disk) around the
binary may have been established at the end of the common envelope phase, and
the tidal torques caused by the gravitational interaction between the disk and
the binary can efficiently extract the orbital angular momentum from the
system. We find that only if M dwarf has an ultra-high wind loss rates of , and a large fraction () of
wind loss is fed into the CB disk, the loss rates of angular momentum via the
CB disk can interpret the period change observed in NN Ser. Such a wind loss
rate and -value seem to be incredible. Hence it seems that the presence
of a third body in a long orbit around the binary might account for the
changing period of NN Ser.Comment: 4 pages, accepted for publication in A&A Letter
Augmented Go & See: An approach for improved bottleneck identification in production lines
Bottlenecks in production lines are often shifting and thus hard to identify. They lead to decreased output, longer throughput times and higher work in progress. Go & See is a well-established Lean practice where managers go to the shop floor to see the problems first hand. Mixed reality is a promising technology to improve transparency in complex production environments. Until recently, mixed reality applications have been very demanding in terms of computing power requiring high performance hardware. This paper presents an approach for real-time KPI visualization using mixed reality for bottleneck identification in production lines relying on the bring-your-own device principle. The developed application uses image recognition to identify work stations and visualizes cycle times and work in progress in augmented reality. With this additional information, it is possible to discern different root causes for bottlenecks, for example systematically higher or varying cycle times due to breakdowns. This solution can be classified according to the acatech industry 4.0 maturity model as a level 3 - transparency - application. It could be shown that the identification of bottlenecks and underlying reasons has been improved compared to standard Go & See
K-band spectroscopy of pre-cataclysmic variables
Aims. There exists now substantial evidence for abundance anomalies in a number of cataclysmic variables (CVs), indicating that the photosphere of the secondary star incorporates thermonuclear processed material. However, the spectral energy distribution in CVs is usually dominated by the radiation produced by the accretion process, severely hindering an investigation of the stellar components.
On the other hand, depending on how the secondary star has acquired such material, the above mentioned abundance anomalies could also be present in pre-CVs, i.e. detached white/red dwarf binaries that will eventually evolve into CVs, but have not yet started mass transfer, and therefore allow for an unobstructed view on the secondary star at infrared wavelengths.
Methods. We have taken K-band spectroscopy of a sample of 13 pre-CVs in order to examine them for anomalous chemical abundances. In particular, we study the strength of the 12CO and 13CO absorption bands that have been found diminished and enhanced, respectively, in similar studies of CVs.
Results. All our systems show CO abundances that are within the range observed for single stars. The weakest 12CO bands with respect to the spectral type are found in the pre-CV BPM 71214, although on a much smaller scale than observed in CVs. Furthermore there is no evidence for enhanced 13CO. Taking into account that our sample is subject to the present observational bias that favours the discovery of young pre-CVs with secondary stars of late spectral types, we can conclude the following: 1) our study provides
observational proof that the CO anomalies discovered in certain CVs are not due to any material acquired during the common envelope phase, and 2) if the CO anomalies in certain CVs are not due to accretion of processed material during nova outburst, then the progenitors of these CVs are of a significantly different type than the currently known sample of pre-CVs
The planets around NN Serpentis : still there
We present 25 new eclipse times of the white dwarf binary NN Ser taken with the high-speed camera ULTRACAM on the William Herschel Telescope and New Technology Telescope, the RISE camera on the Liverpool Telescope and HAWK-I on the Very Large Telescope to test the two-planet model proposed to explain variations in its eclipse times measured over the last 25 yr. The planetary model survives the test with flying colours, correctly predicting a progressive lag in eclipse times of 36 s that has set in since 2010 compared to the previous 8 yr of precise times. Allowing both orbits to be eccentric, we find orbital periods of 7.9 ± 0.5 and 15.3 ± 0.3 yr, and masses of 2.3 ± 0.5 and 7.3 ± 0.3 MJ. We also find dynamically long-lived orbits consistent with the data, associated with 2:1 and 5:2 period ratios. The data scatter by 0.07 s relative to the best-fitting model, by some margin the most precise of any of the proposed eclipsing compact object planet hosts. Despite the high precision, degeneracy in the orbit fits prevents a significant measurement of a period change of the binary and of N-body effects. Finally, we point out a major flaw with a previous dynamical stability analysis of NN Ser, and by extension, with a number of analyses of similar systems
Archeological Of The Proposed FM 1626 Pass-Through Toll Project From Ranch-To-Market 967 To Farm-To-Market 2770 In Hays County, Texas
Hicks & Company archeologists conducted an intensive, 100-percent linear archeological survey of approximately 3.3 miles of proposed expansions to Farm-to-Market (FM) 1626 west of the city of Buda, Hays County, Texas. The survey was conducted between July 2008 and October 2016 for compliance with the Antiquities Code of Texas and Section 106 of the National Historic Preservation Act on behalf of Hays County, the project engineer Klotz Associates, and the Texas Department of Transportation (TxDOT). The Area of Potential Effects (APE) for the proposed project is composed of 54.3 acres of existing right of way and 8.08 acres of proposed expanded right of way (measuring 62.38 acres of existing plus proposed expanded right of way), and approximately 1.07 acres of temporary construction easements located outside of the existing or proposed right of way. While the proposed expanded right of way corridor has been determined, the project engineer requested that a 200-foot-wide corridor be investigated (extending 100 feet in either direction from the existing centerline) to allow for flexibility in road design, potential utility relocation, and other possible areas of concern, resulting in a total of approximately 81 acres of land surveyed. Investigations were coordinated with the Texas Historical Commission through TxDOT under Texas Antiquities Committee Permit Number 4981.
On three occasions between July 28, 2008, and August 10, 2009 Hicks & Company archeologists conducted an intensive linear archeological survey of the proposed FM 1626 improvements project west of the city of Buda, Texas, on behalf of Hays County and TxDOT, returning to the field on January 21, 2016 to survey for proposed temporary construction easements located outside of the existing right of way or proposed new right of way, and again on October 26, 2016 to survey proposed new right of way in previously inaccessible parcels, completing the survey. The survey consisted of pedestrian inspection supplemented by shovel testing (N=102) and mechanical backhoe trench excavations (N=7) in the area north of Onion Creek. One backhoe trench excavated on the north bank of Onion Creek was positive for two pieces of lithic debitage, along with 32 shovel tests throughout the APE that were positive for cultural materials. One previously unrecorded site (Site 41HY449) was documented during the survey. This prehistoric surficial scatter does not meet the significance criteria for listing on the National Register of Historic Places (NRHP) or as a State Antiquities Landmark (SAL). In addition to this newly recorded site, archeologists visited elements of seven previously recorded sites (Sites 41HY199-202, 41HY209-210, and 41HY219) within the APE. Elements of one of these, Site 41HY200, could not be found within the archeological APE. Of these, only elements of Site 41HY201 are considered to have potential to deem the site eligible for inclusion on the NRHP or for designation as an SAL. The project engineer has altered plans in the vicinity of the site to avoid impacts to those resources. All other sites were found to be heavily disturbed, no longer extant, or within shallow surficial contexts atop bedrock with limited research value.
Archeologists also visited the expansion areas adjacent to historic Barton Cemetery. Although the cemetery lies in close proximity to the APE, the County proposes no expansions in the immediate vicinity of the cemetery beyond a proposed retaining wall with riprap slope within the existing right of way outside the cemetery. This retaining wall is to be constructed approximately ten feet within current existing right of way. By design, retaining walls planned for this project will be fixed in place to concrete leveling pads set in place on top of the current grade and supported by earth reinforcement buildup of imported fill material. During survey, an overgrown road or trail that follows the current cemetery fenceline reinforces the assumption that the existing cemetery boundary served as the historic boundary as well, significantly reducing the potential for unmarked burials to be located within the current archeological APE. Construction within the APE is recommended to proceed with no further cultural resources investigation. The current investigations followed a no-collection policy. All projectrelated records, forms, and photographs will be permanently housed at the Texas Archeological Research Laboratory in Austin, Texas
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Metal-metal multiply bonded complexes of technetium. Final report
The primary objective of this project was to explore and develop the area of technetium metal-metal multiple bond chemistry. At the outset of the project, examples of metal-metal multiply bonded complexes of technetium were primarily limited to those supported by halide and carboxylate ligands. As a result, we intended to significantly expand the number of complexes containing Tc-Tc multiple bonds using ligands other than carboxylates or halides. In order to achieve this goal, the results obtained from years of dirhenium research was used as a guide for the development of new technetium compounds. Our emphasis, however, was on pursuing unanticipated results and exploiting the inherent differences between technetium and rhenium in order to develop chemistry beyond that which exists for rhenium. We have focused our attention on the preparation of dinuclear complexes with ligand sets that are known to support dinuclear metal-metal bonded cores in a variety of different metal oxidation states. Investigation of the consequences of electron addition and removal from metal-metal bonding manifold on the structural and physical properties of such dinuclear species will provide vital information regarding the electronic structure of Tc-Tc multiply bonded compounds
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