3,941 research outputs found
The Weihai Observatory search for close-in planets orbiting giant stars
Planets are known to orbit giant stars, yet there is a shortage of planets
orbiting within ~0.5 AU (P<100 days). First-ascent giants have not expanded
enough to engulf such planets, but tidal forces can bring planets to the
surface of the star far beyond the stellar radius. So the question remains: are
tidal forces strong enough in these stars to engulf all the missing planets? We
describe a high-cadence observational program to obtain precise radial
velocities of bright giants from Weihai Observatory of Shandong University. We
present data on the planet host Beta Gem (HD 62509), confirming our ability to
derive accurate and precise velocities; our data achieve an rms of 7.3 m/s
about the Keplerian orbit fit. This planet-search programme currently receives
~100 nights per year, allowing us to aggressively pursue short-period planets
to determine whether they are truly absent.Comment: Accepted for publication in PAS
Four lanthanide-carboxylate coordination polymers with mixed 2,3-naphthalenedicarboxylate and phen ligands: syntheses, structures, luminescent and magnetic properties
Four new lanthanide-carboxylate coordination polymers of the formula [Ln3L4(phen)4(H2O)4](ClO4)·2H2O, (Ln = Dy (1), Tb (2), Ho (3) and Er (4), L = 2,3-naphthalenedicarboxylate and phen = 1,10-phenanthroline) were solvothermally synthesized. Their structures as well as magnetic and photoluminescent properties were completely investigated. Complexes 1-4 are isostructural and exhibit 1D ribbon-like chains with envelope-like sixteen-membered rings. The DyIII and TbIII complexes show the corresponding characteristic luminescence in the visible region and the ErIII complex shows luminescence in the near-infrared region upon excitation with UV rays. Studies on the magnetic properties are reported. The Dy(III) analog complex 1 exhibits slow magnetic relaxation and could be a new example of a Dy(III) SMM (single molecule magnet)
Rotating Night Shift Work and Risk of Type 2 Diabetes: Two Prospective Cohort Studies in Women
An Pan and colleagues examined data from two Nurses' Health Studies and found that extended periods of rotating night shift work were associated with a modestly increased risk of type 2 diabetes, partly mediated through body weight
Enumerating Query Plans via Conditional Tableau Interpolation
Database query optimization studies the problem of finding equivalent and efficient query execution plans for user queries under schema constraints. Logic-based approaches to query optimization leverage automated theorem proving and Craig interpolation to enumerate query plans that are correct and performance-optimal. In this thesis, we investigate and improve one of the state-of-the-art logic-based query optimizers – the Interpolation Test Bed (ITB).
We begin by formally capturing the physical data independence framework and query optimization problem with first-order logic. Then, we give a gentle introduction to the classical results from logic that form the basis of logic-based query optimizers.
We re-establish the correctness of ITB’s conditional tableau interpolation mechanism by reduction to free-variable tableau interpolation. To facilitate the reduction proof, we introduce interpolation rules for the free-variable tableau and prove the correctness of interpolation. Then we show the correctness of conditional tableau interpolation by reduction.
We investigate a limitation of ITB’s forward chaining design, which causes missing optimal plans. To address this limitation, we propose a rewriting procedure inspired by Magic Set Transformation (MST), to extend the plan space for the current ITB system. We show that the propose rewriting procedure effectively generates the missing query plans, which are otherwise not found, while accommodating the existing forward chaining design
Linkages between nitrogen cycling, nitrogen isotopes, and environmental properties in paleo-lake basins
This work was funded by the National Natural Science Foundation of China (no. 41830425). E.E. Stüeken acknowledges funding from a Natural Environment Research Council grant (no. NE/V010824/1).The linkages between nitrogen cycling, nitrogen isotopes, and environmental properties are fundamental for reconstructing nitrogen biogeochemistry. While the impact of ocean redox changes on nitrogen isotopes is relatively well understood, it is poorly known how nitrogen responds to changes in pH and salinity. To fill the knowledge gap, we explore the effects of these environmental parameters using a well-controlled set of samples from Carboniferous−Paleogene lake sediments in China. Our results show that the threshold of 10−12‰ in δ15N works to distinguish alkaline (pH > 9) from circum-neutral conditions. Elevated Mo levels in the alkaline samples support the idea of NH3 volatilization from a reducing water column in an alkaline setting. For non-alkaline lakes, δ15N values tend to be higher (up to +10‰) in more saline, anoxic settings, which is attributed to either the expansion of stagnant anoxic waters spurring water-column denitrification or a shift from plant-based toward more microbially dominated ecosystems or both. Our results imply that salinity-induced redox stratification and basicity can alter nitrogen biogeochemical cycling beyond what is shown by the marine nitrogen isotope record alone. This finding will result in an improved understanding of the dynamic controls of δ15N in sediments and lead to better biogeochemical interpretations of paleo-environmental conditions from unknown environmental settings on Earth and beyond Earth.PostprintPeer reviewe
User-centered Evaluation of Metadata Schema for Murals: Preliminary Results from A Survey Study
There has not been a well-accepted metadata schema for murals as an important type of cultural heritage. This paper reports an ongoing study and preliminary results on evaluating a draft metadata schema of murals from the end-user perspective. Based on the results of an earlier interview-based evaluation, a questionnaire was designed and 185 effective responses were collected from potential users. “Work type”, “Title”, and “Creation date” were identified as the most important metadata elements, and the most useful elements for supporting the searching, browsing, and organizing information about murals. In summary, findings of this study contribute to polishing the design of the metadata schema for murals
Three lanthanide complexes with mixed salicylate and 1,10-phenanthroline: syntheses, crystal structures, and luminescent/magnetic properties
Three new lanthanide complexes incorporating salicylate (HSA or SA) and 1,10-phenanthroline (phen), Ln(3)(HSA)(5)(SA)(2)(phen)(3) [Ln=Ho (1) and Er (2)], and Sm-2(HSA)(2)(SA)(2)(phen)(3) (3), have been synthesized. X-ray structural analysis reveals that 1 and 2 are isostructural with a trinuclear pattern, and 3 exhibits a binuclear structure. Comparison of the structural differences between 1/2 and 3 suggests that the identity of metal plays an important role in construction of such complexes. The magnetic properties of 1 are discussed. Moreover, 2 and 3 are both photoluminescent materials, and their emission properties are closely related to their corresponding Ln(III) centers
How Children Move: Activity Pattern Characteristics in Lean and Obese Chinese Children
Physical activity and sedentary behavior are central components of lifetime weight control; however, our understanding of dimensions of these behaviors in childhood is limited. This study investigated free-living activity pattern characteristics and the individual variability of these characteristics in 84 lean and obese Chinese children (7–9 y) during the school day and over the weekend. Activity pattern characteristics were established from triaxial accelerometry (StayHealthy RT3). Results indicated that children's free-living activity is characterized by many short-duration, low-intensity bouts of movement. Obese children take longer rest intervals between bouts and engage in fewer activity bouts both at school and at home. Intraindividual variability in activity patterns was low during school days but high for the rest intervals between bouts and number of activity bouts per day at the weekend. Finding ways to reduce the rest time between bouts of movement and increase the number of movement bouts a child experiences each day is an important next step
Current state of neuroprotective therapy using antibiotics in human traumatic brain injury and animal models
TBI is a leading cause of death and disability in young people and older adults worldwide. There is no gold standard treatment for TBI besides surgical interventions and symptomatic relief. Post-injury infections, such as lower respiratory tract and surgical site infections or meningitis are frequent complications following TBI. Whether the use of preventive and/or symptomatic antibiotic therapy improves patient mortality and outcome is an ongoing matter of debate. In contrast, results from animal models of TBI suggest translational perspectives and support the hypothesis that antibiotics, independent of their anti-microbial activity, alleviate secondary injury and improve neurological outcomes. These beneficial effects were largely attributed to the inhibition of neuroinflammation and neuronal cell death. In this review, we briefly outline current treatment options, including antibiotic therapy, for patients with TBI. We then summarize the therapeutic effects of the most commonly tested antibiotics in TBI animal models, highlight studies identifying molecular targets of antibiotics, and discuss similarities and differences in their mechanistic modes of action
On the Performance of a Multi Story Irregular Apartment Building Model Under Seismic Load in Indonesian Moderately High Seismicity Region
Purbalingga is regency with a potential moderately high seismicity requiring compliance of planning and implementation rules of the earthquake-resistant structural system. The purpose of this research is to evaluate the performance of a ten-story irregular apartment building model in Purbalingga due to the seismic load. The study is necessarily conducted to provide information on impacts and mitigation strategies that should be implemented. This research was conducted based on the seismic capacity of 2002 and 2012 Indonesian National Standard (SNI) including linear static analysis, dynamic response analysis, and pushover analysis. Based on the direct static review, it shows that the base shear is reduced and the drift ratio level decreases respectively for X and Y direction.Meanwhile, based on the dynamic response analysis, the drift ratio level also decreases respectively for X and Y direction. Also, the pushover analysis indicates that the performance of this apartment building model is still at Immediate Occupancy (IO) level as the post-earthquake damage state that remains safe to occupy, essentially retains the pre-earthquake design strength and stiffness of the structure. The risk of life-threatening injury as a result of structural damage is very low, and although some minor structural repairs may be appropriate, these would generally not be required before occupanc
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