565 research outputs found
Misaligned spin and orbital axes cause the anomalous precession of DI Herculis
The orbits of binary stars precess as a result of general relativistic
effects, forces arising from the asphericity of the stars, and forces from
additional stars or planets in the system. For most binaries, the theoretical
and observed precession rates are in agreement. One system, however -- DI
Herculis -- has resisted explanation for 30 years. The observed precession rate
is a factor of four slower than the theoretical rate, a disagreement that once
was interpreted as evidence for a failure of general relativity. Among the
contemporary explanations are the existence of a circumbinary planet and a
large tilt of the stellar spin axes with respect to the orbit. Here we report
that both stars of DI Herculis rotate with their spin axes nearly perpendicular
to the orbital axis (contrary to the usual assumption for close binary stars).
The rotationally induced stellar oblateness causes precession in the direction
opposite to that of relativistic precession, thereby reconciling the
theoretical and observed rates.Comment: Nature, in press [11 pg
Endothelin-1 Predicts Hemodynamically Assessed Pulmonary Arterial Hypertension in HIV Infection.
BackgroundHIV infection is an independent risk factor for PAH, but the underlying pathogenesis remains unclear. ET-1 is a robust vasoconstrictor and key mediator of pulmonary vascular homeostasis. Higher levels of ET-1 predict disease severity and mortality in other forms of PAH, and endothelin receptor antagonists are central to treatment, including in HIV-associated PAH. The direct relationship between ET-1 and PAH in HIV-infected individuals is not well described.MethodsWe measured ET-1 and estimated pulmonary artery systolic pressure (PASP) with transthoracic echocardiography (TTE) in 106 HIV-infected individuals. Participants with a PASP ≥ 30 mmHg (n = 65) underwent right heart catheterization (RHC) to definitively diagnose PAH. We conducted multivariable analysis to identify factors associated with PAH.ResultsAmong 106 HIV-infected participants, 80% were male, the median age was 52 years and 77% were on antiretroviral therapy. ET-1 was significantly associated with higher values of PASP [14% per 0.1 pg/mL increase in ET-1, p = 0.05] and PASP ≥ 30 mmHg [PR (prevalence ratio) = 1.24, p = 0.012] on TTE after multivariable adjustment for PAH risk factors. Similarly, among the 65 individuals who underwent RHC, ET-1 was significantly associated with higher values of mean pulmonary artery pressure and PAH (34%, p = 0.003 and PR = 2.43, p = 0.032, respectively) in the multivariable analyses.ConclusionsHigher levels of ET-1 are independently associated with HIV-associated PAH as hemodynamically assessed by RHC. Our findings suggest that excessive ET-1 production in the setting of HIV infection impairs pulmonary endothelial function and contributes to the development of PAH
A new concept for the combination of optical interferometers and high-resolution spectrographs
The combination of high spatial and spectral resolution in optical astronomy
enables new observational approaches to many open problems in stellar and
circumstellar astrophysics. However, constructing a high-resolution
spectrograph for an interferometer is a costly and time-intensive undertaking.
Our aim is to show that, by coupling existing high-resolution spectrographs to
existing interferometers, one could observe in the domain of high spectral and
spatial resolution, and avoid the construction of a new complex and expensive
instrument. We investigate in this article the different challenges which arise
from combining an interferometer with a high-resolution spectrograph. The
requirements for the different sub-systems are determined, with special
attention given to the problems of fringe tracking and dispersion. A concept
study for the combination of the VLTI (Very Large Telescope Interferometer)
with UVES (UV-Visual Echelle Spectrograph) is carried out, and several other
specific instrument pairings are discussed. We show that the proposed
combination of an interferometer with a high-resolution spectrograph is indeed
feasible with current technology, for a fraction of the cost of building a
whole new spectrograph. The impact on the existing instruments and their
ongoing programs would be minimal.Comment: 27 pages, 9 figures, Experimental Astronomy; v2: accepted versio
New Therapeutic Strategies for Systemic Sclerosis—a Critical Analysis of the Literature
Systemic sclerosis (SSc) is a multi-system disease characterized by skin
fibrosis and visceral disease. Therapy is organ and pathogenesis targeted. In
this review, we describe novel strategies in the treatment of SSc. Utilizing the
MEDLINE and the COCHRANE REGISTRY, we identified open trials, controlled
trials, for treatment of SSc from 1999 to April 2005. We used the terms scleroderma,
systemic sclerosis, Raynaud's phenomenon, pulmonary hypertension,
methotrexate, cyclosporin, tacrolimus, relaxin, low-dose penicillamine, IVIg,
calcium channel blockers, losartan, prazocin, iloprost, N-acetylcysteine, bosentan,
cyclophosphamide, lung transplantation, ACE inhibitors,
anti-thymocyte globulin, and stem cell transplantation. Anecdotal reports were
omitted
Public drunkenness as a nuisance in Ghent (Belgium) and Trento (Italy)
This article explores the reality of the nuisance of public drunkenness in one nightlife location of Ghent (Belgium) and in one of Trento (Italy) and inspects the way alcohol-related disorder is viewed and tackled by police officers there. Drawing on the literature arguing for the existence of different "cultures of drinking" in western and southern European countries, a distinct reality of the nuisance of public drunkenness was hypothesized to be present in these two cities. Against the backdrop of cultural criminology scholarship and of the national literature on policing practices, it was expected that the physical/aesthetic appearance of street drinkers would differently impact on the way police officers there represent alcohol-related disorder and enforce national and local nuisance regulations. The gathered data indicate that while drinking patterns and connected disorderly behavior do not significantly vary in Ghent and in Trento, the aesthetic/physical characteristics of certain groups of people play a role in shaping the representations of some police officers in Trento. The study concludes that cultural and context-specific factors, including those linked to the cultures of drinking and to aesthetics, should be considered in criminological research to more fully understand and explain the different policing views on and attitudes to alcohol-related disorder in inner-city nightlife areas. In its conclusions, the article also highlights some directions for future research
The Rossiter-McLaughlin effect in Exoplanet Research
The Rossiter-McLaughlin effect occurs during a planet's transit. It provides
the main means of measuring the sky-projected spin-orbit angle between a
planet's orbital plane, and its host star's equatorial plane. Observing the
Rossiter-McLaughlin effect is now a near routine procedure. It is an important
element in the orbital characterisation of transiting exoplanets. Measurements
of the spin-orbit angle have revealed a surprising diversity, far from the
placid, Kantian and Laplacian ideals, whereby planets form, and remain, on
orbital planes coincident with their star's equator. This chapter will review a
short history of the Rossiter-McLaughlin effect, how it is modelled, and will
summarise the current state of the field before describing other uses for a
spectroscopic transit, and alternative methods of measuring the spin-orbit
angle.Comment: Review to appear as a chapter in the "Handbook of Exoplanets", ed. H.
Deeg & J.A. Belmont
Decreased expression of dual-specificity phosphatase 9 is associated with poor prognosis in clear cell renal cell carcinoma
Background: The molecular mechanisms involved in the development and progression of clear cell renal cell carcinomas (ccRCCs) are poorly understood. The objective of this study was to analyze the expression of dual-specificity phosphatase 9 (DUSP-9) and determine its clinical significance in human ccRCCs. Methods: The expression of DUSP-9 mRNA was determined in 46 paired samples of ccRCCs and adjacent normal tissues by using real-time qPCR. The expression of the DUSP-9 was determined in 211 samples of ccRCCs and 107 paired samples of adjacent normal tissues by immunohistochemical analysis. Statistical analysis was performed to define the relationship between the expression of DUSP-9 and the clinical features of ccRCC. Results: The mRNA level of DUSP-9, which was determined by real-time RT-PCR, was found to be significantly lower in tumorous tissues than in the adjacent non-tumorous tissues (p < 0.001). An immunohistochemical analysis of 107 paired tissue specimens showed that the DUSP-9 expression was lower in tumorous tissues than in the adjacent non-tumorous tissues (p < 0.001). Moreover, there was a significant correlation between the DUSP-9 expression in ccRCCs and gender (p = 0.031), tumor size (p = 0.001), pathologic stage (p = 0.001), Fuhrman grade (p = 0.002), T stage (p = 0.001), N classification (p = 0.012), metastasis (p = 0.005), and recurrence (p < 0.001). Patients with lower DUSP-9 expression had shorter overall survival time than those with higher DUSP-9 expression (p < 0.001). Multivariate analysis indicated that low expression of the DUSP-9 was an independent predictor for poor survival of ccRCC patients. Conclusion: To our knowledge, this is the first study that determines the relationship between DUSP-9 expression and prognosis in ccRCC. We found that decreased expression of DUSP-9 is associated with poor prognosis in ccRCC. DUSP-9 may represent a novel and useful prognostic marker for ccRCC
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