6,550 research outputs found
The Pion-Nucleon coupling constant from np charge exchange scattering
A novel extrapolation method has been used to deduce the charged Pion-Nucleon
coupling constant from backward differential scattering cross sections. We
applied it to new measurements performed at 162 MeV at the The Svedberg
Laboratory in Uppsala. In the angular range , the
carefully normalized data are steeper than those of most previous measurements.
The extracted value, , in good agreement with
the classical value, is higher than those determined in recent nucleon-nucleon
partial-wave analyses.Comment: 6 pages, 3 encapsulated figures, epsfig, menu97.cls (included
Identifying Agile Requirements Engineering Patterns in Industry
Agile Software Development (ASD) is gaining in popularity in today´s business world. Industry is adopting agile methodologies both to accelerate value delivery and to enhance the ability to deal with changing requirements. However, ASD has a great impact on how Requirements Engineering (RE) is carried out in agile environments. The integration of Human-Centered Design (HCD) plays an important role due to the focus on user and stakeholder involvement. To this end, we aim to introduce agile RE patterns as main objective of this paper. On the one hand, we will describe our pattern mining process based on empirical research in literature and industry. On the other hand, we will discuss our results and provide two examples of agile RE patterns. In sum, the pattern mining process identifies 41 agile RE patterns. The accumulated knowledge will be shared by means of a web application.Ministerio de EconomÃa y Competitividad TIN2013-46928-C3-3-RMinisterio de EconomÃa y Competitividad TIN2016-76956-C3-2-RMinisterio de EconomÃa y Competitividad TIN2015-71938-RED
Which Is the Most Cost-efficient Alternative, a New Build or the Rehabilitation of a Cultural Heritage Site?
Given the choice between the rehabilitation of a cultural heritage site and a new build, recent history in Norway shows that the new build is often chosen, with the justification of cost efficiency.
This paper compares approaches to cultural heritage sites from a property development and a protection of cultural heritage point of view to test this judgment. These two professional fields overlap and need to cooperate. Thus, a closer look at their similarities and differences should provide valuable insights.
This paper applies a case-study method to a large country estate building at a NATO air base in need of office space. The building has legal protection at the national level. Costs are calculated for three scenarios for new offices: rehabilitation of the protected building, a new build, and renting. All alternatives include legally mandated maintenance of the protected building, as the same public body carries out both tasks.
Of the three alternatives, the new build and renting were the most expensive over a thirty-year time span. Rehabilitation was the most economical. These findings indicate that owners of protected buildings should investigate possibilities to activate such buildings, due to not only their cultural heritage values, but also their economic potential
3D simulations of Einstein's equations: symmetric hyperbolicity, live gauges and dynamic control of the constraints
We present three-dimensional simulations of Einstein equations implementing a
symmetric hyperbolic system of equations with dynamical lapse. The numerical
implementation makes use of techniques that guarantee linear numerical
stability for the associated initial-boundary value problem. The code is first
tested with a gauge wave solution, where rather larger amplitudes and for
significantly longer times are obtained with respect to other state of the art
implementations. Additionally, by minimizing a suitably defined energy for the
constraints in terms of free constraint-functions in the formulation one can
dynamically single out preferred values of these functions for the problem at
hand. We apply the technique to fully three-dimensional simulations of a
stationary black hole spacetime with excision of the singularity, considerably
extending the lifetime of the simulations.Comment: 21 pages. To appear in PR
The stringy nature of the 2d type-0A black hole
We investigate the thermodynamics of the RR charged two-dimensional type-0A
black hole background at finite temperature, and compare with known 0A matrix
model results. It has been claimed that there is a disagreement for the free
energy between the spacetime and the dual matrix model. Here we find that this
discrepancy is sensitive to how the cutoff is implemented on the spacetime
side. In particular, the disagreement is resolved once we put the cutoff at a
fixed distance away from the horizon, as opposed to a fixed position in space.
Furthermore, the mass and the entropy of the black hole itself add up to an
analytic contribution to the free energy, which is precisely reproduced by the
0A matrix model. We also use results from the 0A matrix model to predict the
next to leading order contribution to the entropy of the black hole. Finally,
we note that the black hole is characterized by a Hagedorn growth in its
density of states below the Hagedorn temperature. This, together with other
results, suggests there is a phase transition at this temperature.Comment: 1+21 pages; v2: Substantial changes in the body of the paper, main
results the same. Clarified discussion on the thermodynamics, added section
on a phase transition, references added. v3: Typos corrected. v4: Final
version, to appear in JHE
On the well posedness of the Baumgarte-Shapiro-Shibata-Nakamura formulation of Einstein's field equations
We give a well posed initial value formulation of the
Baumgarte-Shapiro-Shibata-Nakamura form of Einstein's equations with gauge
conditions given by a Bona-Masso like slicing condition for the lapse and a
frozen shift. This is achieved by introducing extra variables and recasting the
evolution equations into a first order symmetric hyperbolic system. We also
consider the presence of artificial boundaries and derive a set of boundary
conditions that guarantee that the resulting initial-boundary value problem is
well posed, though not necessarily compatible with the constraints. In the case
of dynamical gauge conditions for the lapse and shift we obtain a class of
evolution equations which are strongly hyperbolic and so yield well posed
initial value formulations
Sustainability of multi-field inflation and bound on string scale
We study the effects of the interaction terms between the inflaton fields on
the inflationary dynamics in multi-field models. With power law type potential
and interactions, the total number of e-folds may get considerably reduced and
can lead to unacceptably short period of inflation. Also we point out that this
can place a bound on the characteristic scale of the underlying theory such as
string theory. Using a simple multi-field chaotic inflation model from string
theory, the string scale is constrained to be larger than the scale of grand
unified theory.Comment: (v1) 9 pages, 1 figure;(v2) 10 pages, references added; (v3) 15
pages, 4 figures, more discussions about parameters and observable
quantities, references added, to appear in Modern Physics Letters
The discrete energy method in numerical relativity: Towards long-term stability
The energy method can be used to identify well-posed initial boundary value
problems for quasi-linear, symmetric hyperbolic partial differential equations
with maximally dissipative boundary conditions. A similar analysis of the
discrete system can be used to construct stable finite difference equations for
these problems at the linear level. In this paper we apply these techniques to
some test problems commonly used in numerical relativity and observe that while
we obtain convergent schemes, fast growing modes, or ``artificial
instabilities,'' contaminate the solution. We find that these growing modes can
partially arise from the lack of a Leibnitz rule for discrete derivatives and
discuss ways to limit this spurious growth.Comment: 18 pages, 22 figure
The P_33(1232) resonance contribution into the amplitudes M_{1+}^{3/2},E_{1+}^{3/2},S_{1+}^{3/2} from an analysis of the p(e,e'p)\pi^0 data at Q^2 = 2.8, 3.2, and 4 (GeV/c)^2 within dispersion relation approach
Within the fixed-t dispersion relation approach we have analysed the TJNAF
and DESY data on the exclusive p(e,e'p)\pi^0 reaction in order to find the
P_{33}(1232) resonance contribution into the multipole amplitudes
M_{1+}^{3/2},E_{1+}^{3/2},S_{1+}^{3/2}. As an input for the resonance and
nonresonance contributions into these amplitudes the earlier obtained solutions
of the integral equations which follow from dispersion relations are used. The
obtained values of the ratio E2/M1 for the \gamma^* N \to P_{33}(1232)
transition are: 0.039\pm 0.029, 0.121\pm 0.032, 0.04\pm 0.031 for Q^2= 2.8,
3.2, and 4 (GeV/c)^2, respectively. The comparison with the data at low Q^2
shows that there is no evidence for the presence of the visible pQCD
contribution into the transition \gamma N \to P_{33}(1232) at Q^2=3-4 GeV^2.
The ratio S_{1+}^{3/2}/M_{1+}^{3/2} for the resonance parts of multipoles is:
-0.049\pm 0.029, -0.099\pm 0.041, -0.085\pm 0.021 for Q^2= 2.8, 3.2, and 4
(GeV/c)^2, respectively. Our results for the transverse form factor G_T(Q^2) of
the \gamma^* N \to P_{33}(1232) transition are lower than the values obtained
from the inclusive data. With increasing Q^2, Q^4G_T(Q^2) decreases, so there
is no evidence for the presence of the pQCD contribution here too
Pulmonary Hypertension in Patients with Chronic Fibrosing Idiopathic Interstitial Pneumonias
Background Pulmonary hypertension (PH) is a common finding in patients with chronic fibrosing idiopathic interstitial pneumonias (IIP). Little is known about the response to pulmonary vasodilator therapy in this patient population. COMPERA is an international registry that prospectively captures data from patients with various forms of PH receiving pulmonary vasodilator therapies. Methods We retrieved data from COMPERA to compare patient characteristics, treatment patterns, response to therapy and survival in newly diagnosed patients with idiopathic pulmonary arterial hypertension (IPAH) and PH associated with IIP (PH-IIP). Results Compared to patients with IPAH (n = 798), patients with PH-IIP (n = 151) were older and predominantly males. Patients with PH-IIP were treated predominantly with phosphodiesterase-5 inhibitors (88% at entry, 87% after 1 year). From baseline to the first follow-up visit, the median improvement in 6MWD was 30 m in patients with IPAH and 24.5 m in patients with PH-IIP (p = 0.457 for the difference between both groups). Improvements in NYHA functional class were observed in 22.4% and 29.5% of these patients, respectively (p = 0.179 for the difference between both groups). Survival rates were significantly worse in PH-IIP than in IPAH (3-year survival 34.0 versus 68.6%; p<0.001). Total lung capacity, NYHA class IV, and mixed-venous oxygen saturation were independent predictors of survival in patients with PH-IIP. Conclusions Patients with PH-IIP have a dismal prognosis. Our results suggest that pulmonary vasodilator therapy may be associated with short-term functional improvement in some of these patients but it is unclear whether this treatment affects survival
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