296 research outputs found
The Utility of Self-Assessment in Predicting Program Office Estimate Accuracy
The ability of the Program Offices to provide accurate cost estimates is an essential element in planning and programming. Historically, cost estimating has led to budget overruns and continues to be an area of scrutiny and concern. A series of legislative reforms have sought to address each of these perceived underlying causes which are located at all levels of decision making – from the SPO to CADE. The current study is specifically interested in determining how well SPOs are doing. There have not been comprehensive studies on SPO performance. In large part, this deficiency is due to the inability to systematically assess the SPOs. However, a new consolidation of data by AFLCMC has recently made it possible to do such a study. The AFLCMC’s program office estimates in this study will look at the SPOs of AFLCMC and evaluate their cost estimates for growth and determine if their established method of self-assessment provides a predictor of the overall future accuracy of the program estimate
Numerical Simulations of Accretion Disks and Extrasolar Planets
We study mass outflows from astrophysical objects. Using numerical hydrodynamical simulations, we investigate outflows from accretion disks and exoplanets. In the first part of this dissertation, we present the results of Zeus 2D hydrodynamical simulations of the disk photosphere irradiated by strong X–rays that are produced in the innermost part of the disk of an accreting black hole. As expected, the irradiation heats the photosphere and drives a thermal wind. To apply our results to the well– studied X–ray transient source GRO J1655–40, we utilized the observed mass of its black hole and the observed properties of its X–ray radiation for our simulations. To compare our results with observations, we also computed transmitted X–ray spectra based on the wind solution. Our main finding is that the density of the fast–moving part of the wind is more than one order of magnitude lower than that inferred from the observations. Consequently, the model fails to predict spectra with line absorptions as strong and as blueshifted as those observed. However, despite the thermal wind being weak and Compton thin, the ratio between the mass–loss rate and the mass accretion rate is about seven. This high ratio is insensitive to the accretion luminosity, in the limit of lower luminosities. Most of the mass is lost from the disk between 0.07 and 0.2 of the Compton radius. We discovered that beyond this range the wind solution is self-similar. In particular, soon after it leaves the disk, the wind flows at a constant angle with respect to the disk. Overall, the thermal winds generated in our comprehensive simulations do not match the wind spectra observed in GRO J1655–40. This supports the conclusion of Miller et al. and Kallman et al. that the wind in GRO J1655–40, and possibly other X–ray transients, may be driven by magnetic processes. This in turn implies that the disk wind carries even more material than our simulations predict, and, as such, has a very significant impact on the accretion disk structure and dynamics. Motivated by the recent renaissance after the Kepler mission discoveries of about 500 new extrasolar planets, in the second part we analyze problems of the extrasolar planet irradiated by a star interacting with the wind coming from a parent star. This is a full 3D modeling performed using Athena 3D. We use the general model of a spherical object with a cosine distribution of temperature on the irradiated side and constant temperature on the opposite side. The thermal wind arises from the planet and interacts with the wind emanating from the star. We made some simplifications; the Coriolis force is included. We placed constraints on the mass loss from the planet, wind velocities, and dependencies on various parameters, such as: distance from the star, strength of the stars, wind, etc. We created a general model for studying outflows from diverse group of objects of various geometries
LPIS/IACS topics: Land tenure and “at the disposal of”
This material is an introduction and the discussion document about the legal and spatial context of defining agricultural parcels of the Land parcel information system. So far, some EU Member States’ Administrations use legal documents in evidencing the land that is at the farmers’ disposal to be entitled for payment support. None of the acts from EU regulation provides specific provisions how authorities should verify that the farmer holds access and use rights for agricultural parcels he declares. Once legal documents became necessary to evidence the use of land, many issues arise and prevent a farmer to declare actual utilization of agricultural land. MS Authorities put more obligations to the farmer than necessary. Those legal and spatial records are very often not up-to-date and full of inaccuracies, hence should be considered with attention. We provide insights of those discrepancies and provide recommendations to the Member States’ Administrations.JRC.D.5-Food Securit
Improvement of Rural Mobility in European Regions Affected by Demographic Change
Paper presents some of the specific mid-term results of RUMOBIL project. RUMOBIL is project funded by INTERREG CENTRAL EUROPE program. The main objective of RUMOBIL is to improve public transport in rural areas by better connecting them to the national and European transport networks. Project supports transnational cooperation between eight public authorities from Germany, Czech Republic, Poland, Hungary, Slovakia, Croatia and Italy, and their transport entities. These are confronted with a similar challenge to respond to pressures on regional public transport systems caused by demographic change in peripheral areas. Working together provide them with a platform to exchange knowledge, to generate learning through launching pilot applications of state-of-the art tools and solutions, and to revise their transport policies to better suit changing mobility needs. Quicker and more comfortable access by public transport positively contributes to the quality of life in rural areas and supports business activities there. To that aim, a set of evidence-based policy recommendations will be elaborated at the end of the project to improve the capacities of local and regional decision-makers responsible for the design and coordination of public passenger transport in Central European regions affected by demographic change. These recommendations will be presented in the form of the RUMOBIL Model which provides insights in already proven good practices and novel solutions. Main outputs of RUMOBIL project are pilot actions, the elaboration of a RUMOBIL strategy, and policy-decisions to implement this strategy in the eight partner regions through an improvement of their transport plans. Pilot actions allow testing a number of innovative applications during a period 2017-2018 how sparsely populated peripheral areas can be better linked to a primary, secondary or tertiary transport node (access to European and national passenger transport networks)
The Disk-Wind-Jet Connection in the Black Hole H 1743-322
X-ray disk winds are detected in spectrally soft, disk-dominated phases of
stellar-mass black hole outbursts. In contrast, compact, steady, relativistic
jets are detected in spectrally hard states that are dominated by non-thermal
X-ray emission. Although these distinctive outflows appear to be almost
mutually exclusive, it is possible that a disk wind persists in hard states but
cannot be detected via X-ray absorption lines owing to very high ionization.
Here, we present an analysis of a deep, 60 ksec Chandra/HETGS observation of
the black hole candidate H 1743-322 in the low/hard state. The spectrum shows
no evidence of a disk wind, with tight limits, and within the range of ionizing
flux levels that were measured in prior Chandra observations wherein a wind was
clearly detected. In H 1743-322, at least, disk winds are actually diminished
in the low/hard state, and disk winds and jets are likely state-dependent and
anti-correlated. These results suggest that although the launching radii of
winds and jets may differ by orders of magnitude, they may both be tied to a
fundamental property of the inner accretion flow, such as the mass accretion
rate and/or the magnetic field topology of the disk. We discuss these results
in the context of disk winds and jets in other stellar-mass black holes, and
possible launching mechanisms for black hole outflows.Comment: Accepted for publication in ApJ Letter
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A Randomized, Controlled, Phase 2 Study of Maralixibat in the Treatment of Itching Associated With Primary Biliary Cholangitis.
Primary biliary cholangitis (PBC) is typically associated with elevated serum bile acid levels and pruritus, but pruritus is often refractory to treatment with existing therapies. This phase 2 study assessed the efficacy and safety of maralixibat, a selective, ileal, apical, sodium-dependent, bile acid transporter inhibitor, in adults with PBC and pruritus. Adults with PBC and pruritus who had received ursodeoxycholic acid (UDCA) for ≥6 months or were intolerant to UDCA were randomized 2:1 to maralixibat (10 or 20 mg/day) or placebo for 13 weeks in combination with UDCA (when tolerated). The primary outcome was change in Adult Itch Reported Outcome (ItchRO™) average weekly sum score (0, no itching; 70, maximum itching) from baseline to week 13/early termination (ET). The study enrolled 66 patients (maralixibat [both doses combined], n = 42; placebo, n = 24). Mean ItchRO™ weekly sum scores decreased from baseline to week 13/ET with maralixibat (-26.5; 95% confidence interval [CI], -31.8, -21.2) and placebo (-23.4; 95% CI, -30.3, -16.4). The difference between groups was not significant (P = 0.48). In the maralixibat and placebo groups, adverse events (AEs) were reported in 97.6% and 70.8% of patients, respectively. Gastrointestinal disorders were the most frequently reported AEs (maralixibat, 78.6%; placebo, 50.0%). Conclusion: Reductions in pruritus did not differ significantly between maralixibat and placebo. However, a large placebo effect may have confounded assessment of pruritus. Lessons learned from this rigorously designed and executed trial are indispensable for understanding how to approach trials assessing pruritus as the primary endpoint and the therapeutic window of bile acid uptake inhibition as a therapeutic strategy in PBC
Warm Absorbers and Outflows in the Seyfert-1 Galaxy NGC 4051
We present both phenomenological and more physical photoionization models of
the Chandra HETG spectra of the Seyfert-1 AGN NGC 4051. We detect 40 absorption
and emission lines, encompassing highly ionized charge states from O, Ne, Mg,
Si, S and the Fe L-shell and K-shell. Two independent photoionization packages,
XSTAR and Cloudy, were both used to self-consistently model the continuum and
line spectra. These fits detected three absorbing regions in this system with
densities ranging from 10^{10} to 10^{11} cm^{-3}. In particular, our XSTAR
models require three components that have ionization parameters of log \xi =
4.5, 3.3, & 1.0, and are located within the BLR at 70, 300, and 13,000 R_g,
respectively, assuming a constant wind density. Larger radii are inferred for
density profiles which decline with radius. The Cloudy models give a similar
set of parameters with ionization parameters of log \xi = 5.0, 3.6, & 2.2
located at 40, 200, and 3,300 R_g. We demonstrate that these regions are
out-flowing from the system, and carry a small fraction of material out of the
system relative to the implied mass accretion rate. The data suggest that
magnetic fields may be an important driving mechanism.Comment: 21 pages, 11 Figures, Accepted to Ap
On the diversity and complexity of absorption line profiles produced by outflows in Active Galactic Nuclei
Understanding the origin of AGN absorption line profiles and their diversity
could help to explain the physical structure of the accretion flow, and also to
assess the impact of accretion on the evolution of the AGN host galaxies. Here
we present our first attempt to systematically address the issue of the origin
of the complexities observed in absorption profiles. Using a simple method, we
compute absorption line profiles against a continuum point source for several
simulations of accretion disk winds. We investigate the geometrical,
ionization, and dynamical effects on the absorption line shapes. We find that
significant complexity and diversity of the absorption line profile shapes can
be produced by the non-monotonic distribution of the wind velocity, density,
and ionization state. Non-monotonic distributions of such quantities are
present even in steady-state, smooth disk winds, and naturally lead to the
formation of multiple and detached absorption troughs. These results
demonstrate that the part of a wind where an absorption line is formed is not
representative of the entire wind. Thus, the information contained in the
absorption line is incomplete if not even insufficient to well estimate gross
properties of the wind such as the total mass and energy fluxes. In addition,
the highly dynamical nature of certain portions of disk winds can have
important effects on the estimates of the wind properties. For example, the
mass outflow rates can be off up to two orders of magnitude with respect to
estimates based on a spherically symmetric, homogeneous, constant velocity
wind.Comment: 10 pages, 10 figures, to appear in Ap
Symptom Domain Groups of the Patient-Reported Outcomes Measurement Information System Tools Independently Predict Hospitalizations and Re-hospitalizations in Cirrhosis
Background Patient-Reported Outcomes Measurement Information System (PROMIS) tools can identify health-related quality of life (HRQOL) domains that could differentially affect disease progression. Cirrhotics are highly prone to hospitalizations and re-hospitalizations, but the current clinical prognostic models may be insufficient, and thus studying the contribution of individual HRQOL domains could improve prognostication. Aim Analyze the impact of individual HRQOL PROMIS domains in predicting time to all non-elective hospitalizations and re-hospitalizations in cirrhosis. Methods Outpatient cirrhotics were administered PROMIS computerized tools. The first non-elective hospitalization and subsequent re-hospitalizations after enrollment were recorded. Individual PROMIS domains significantly contributing toward these outcomes were generated using principal component analysis. Factor analysis revealed three major PROMIS domain groups: daily function (fatigue, physical function, social roles/activities and sleep issues), mood (anxiety, anger, and depression), and pain (pain behavior/impact) accounted for 77% of the variability. Cox proportional hazards regression modeling was used for these groups to evaluate time to first hospitalization and re-hospitalization. Results A total of 286 patients [57 years, MELD 13, 67% men, 40% hepatic encephalopathy (HE)] were enrolled. Patients were followed at 6-month (mth) intervals for a median of 38 mths (IQR 22–47), during which 31% were hospitalized [median IQR mths 12.5 (3–27)] and 12% were re-hospitalized [10.5 mths (3–28)]. Time to first hospitalization was predicted by HE, HR 1.5 (CI 1.01–2.5, p = 0.04) and daily function PROMIS group HR 1.4 (CI 1.1–1.8, p = 0.01), independently. In contrast, the pain PROMIS group were predictive of the time to re-hospitalization HR 1.6 (CI 1.1–2.3, p = 0.03) as was HE, HR 2.1 (CI 1.1–4.3, p = 0.03). Conclusions Daily function and pain HRQOL domain groups using PROMIS tools independently predict hospitalizations and re-hospitalizations in cirrhotic patients
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