883 research outputs found
Recombining Plasma & Gamma-ray Emission in the Mixed-morphology Supernova Remnant 3C 400.2
3C 400.2 belongs to the mixed morphology supernova remnant class, showing
center-filled X-ray and shell-like radio morphology. We present a study of 3C
400.2 with archival Suzaku and Fermi-LAT observations. We find recombining
plasma (RP) in the Suzaku spectra of north-east and south-east regions. The
spectra of these regions are well described by two-component thermal plasma
models: The hard component is in RP, while the soft component is in collisional
ionization equilibrium (CIE) conditions. The RP has enhanced abundances
indicating that the X-ray emission has an ejecta origin, while the CIE has
solar abundances associated with the interstellar material. The X-ray spectra
of north-west and south-west regions are best fitted by a two-component thermal
plasma model: an ionizing and a CIE plasma. We have detected GeV gamma-ray
emission from 3C 400.2 at the level of 5 assuming a point-like
source model with a power-law (PL) type spectrum. We have also detected a new
GeV source at the level of 13 assuming a Gaussian extension model
with a PL type spectrum in the neighborhood of the SNR. We report the analysis
results of 3C 400.2 and the new extended gamma-ray source and discuss the
nature of gamma-ray emission of 3C 400.2 in the context of existing NANTEN CO
data, DRAO HI data, and the Suzaku X-ray analysis results.Comment: Accepted to be published in the Astrophysical Journa
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Two-sided matching with indifferences
Most of the two-sided matching literature maintains the assumption that agents are never indifferent between any two members of the opposite side. In practice, however, ties in preferences arise naturally and are widespread. Market design needs to handle ties carefully, because in the presence of indifferences, stability no longer implies Pareto efficiency, and the deferred acceptance algorithm cannot be applied to produce a Pareto efficient or a worker-optimal stable matching.
We allow ties in preference rankings and show that the Pareto dominance relation on stable matchings can be captured by two simple operations which involve rematching of workers and firms via cycles or chains. Likewise, the Pareto relation defined via workers' welfare can also be broken down to two similar procedures which preserve stability. Using these structural results we design fast algorithms to compute a Pareto efficient and stable matching, and a worker-optimal stable matching
Executable Modeling for System of Systems Architecting: An Artificial Life Framework
There is a diversity of frameworks and methodologies for enabling architecture developments. Static representation frameworks provide a standardized way to communicate the architecture to stakeholders, but do not provide means to analyze the system states and system behavior. Therefore, there is a need to convert static representation frameworks to executable models. The aim of this paper is to present Artificial Life approaches as a methodology for understanding behavior of System of Systems. For this, an Artificial Life based framework for modeling System of Systems is presented. The framework comprises cognitive architectures embedded in multi-agent models. Financial markets are selected as an analysis domain to demonstrate the framework since they are a good example of self-organizing systems that are nonproprietary and exhibit emergence on a grand scale. From the Artificial Life Framework trader-based architectures are formulated as models to analyze system level behavior. The Artificial Life based framework provides a flexible way of modeling sub-systems of System of Systems and it captures the adaptive and emergent behavior of the system
Pasternak Zeminine Yaslanan Ve Kısmen Akışkan İle Temas Eden Mindlin Plağının Dinamik Davranışı
Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Bu çalışmada Pasternak zeminine oturan ve aynı zamanda durağan bir akışkan alanıyla kısmen temas eden Mindlin plaklarının dinamik davranışı incelenmiştir. Gâteaux türevinden yararlanılarak plak-zemin etkileşimi karışık sonlu eleman yöntemi ile ele alınmış, yayılı kütle matrisinde plak dönel eylemsizlikleri de gözetilmiştir. Akışkan-yapı etkileşimi içinse sınır eleman yönteminden yararlanılmıştır. Uygulanan kabuller, plak-zemin sisteminin akışkanla temas sırasında kendi doğal modlarında titreştiği ve her bir elastik moda karşılık plak ıslak yüzeyi üzerinde bir basınç dağılımının oluştuğu şeklindedir. Akışkan serbest yüzey etkileri sonsuz-frekans kabulü altında ihmal edilmiştir. Ortaya çıkan etkileşim kuvvetleri akışkan eylemsizlik etkisini temsil eden genelleştirilmiş ek su kütlesi formundadır. Sunulan çözüm yaklaşımı örneklerle test edilmiş, zemin varlığının ve akışkan etkileşiminin Mindlin plağının dinamik davranışına olan etkileri parametrik olarak ayrıca incelenmiştir.This study is concerned with the dynamic response of Mindlin plates resting on an Pasternak foundation and simultaneously interacting partially with a quiescent fluid field. Plate-foundation interaction is simulated in the framework of a mixed finite element by employing the Gâteaux differential. Consistent mass matrix formulation is used by considering the rotary inertia. Fluid-structure interaction analysis is carried out by the boundary element method. It is assumed that the plate – elastic foundation system vibrates in its in vacuo eigenmodes when it is in contact with fluid, and that each mode gives rise to a corresponding surface pressure distribution on the wetted surface of the structure. The fluid free-surface effects are neglected by imposing the high-frequency limit condition. The fluid-structure interaction forces are calculated in terms of the generalized hydrodynamic added mass coefficients that represent the inertial effect of the fluid. The methodology is verified, and the influence of foundation and fluid interaction on the dynamic behavior of the Mindlin plate is studied through parametric investigations
Congenital Lymphoedema, Bronchiectasis And Seizure: Case Report
A l0-year-old girl with facial anomalies, mental retardation, peripheral lymphoedema, convulsions, cerebral cortical dysgenetic changes, bronchiectasis and chronic sinusitis is presented. She had features of both yellow nail syndrome and Hennekam syndrome. We think that our case might be a new congenital lymphoedema syndrome or an
intermediate form between these syndromes. East African Medical Journal Vol. 85 (3) 2008: pp. 145-14
miR-199a-3p and miR-214-3p improve the overall survival prediction of muscle- invasive bladder cancer patients after radical cystectomy
To improve the clinical decision-making regarding further treatment management
and follow-up scheduling for patients with muscle-invasive bladder cancer
(MIBC) after radical cystectomy (RC), a better prediction accuracy of
prognosis for these patients is urgently needed. The objective of this study
was to evaluate the validity of differentially expressed microRNAs (miRNAs)
based on a previous study as prognostic markers for overall survival (OS)
after RC in models combined with clinicopathological data. The expression of
six miRNAs (miR-100-5p, miR-130b-3p, miR-141-3p, miR-199a-3p, miR-205-5p, and
miR-214-3p) was measured by RT-qPCR in formalin-fixed, paraffin-embedded
tissue samples from 156 MIBC patients who received RC in three urological
centers. Samples from 2000 to 2013 were used according to their tissue
availability, with follow-up until June 2016. The patient cohort was randomly
divided into a training (n = 100) and test set (n = 56). Seventy-three samples
from adjacent normal tissue were used as controls. Kaplan–Meier, univariate
and multivariate Cox regression, and decision curve analyses were carried out
to assess the association of clinicopathological variables and miRNAs to OS.
Both increased (miR-130b-3p and miR-141-3p) and reduced (miR-100-5p, miR-199a-
3p, and miR-214-3p) miRNA expressions were found in MIBC samples in comparison
to nonmalignant tissue samples (P < 0.0001). miR-199a-3p and miR-214-3p were
independent markers of OS in Cox regression models with the significant
clinicopathological variables age, tumor status, and lymph node status. The
prediction model with the clinicopathological variables was improved by these
two miRNAs in both sets. The predictive benefit was confirmed by decision
curve analysis. In conclusion, the inclusion of both miRNAs into models based
on clinical data for the outcome prediction of MIBC patients after RC could be
a valuable approach to improve prognostic accuracy
Higher Derivative Extension of 6D Chiral Gauged Supergravity
Six-dimensional (1,0) supersymmetric gauged Einstein-Maxwell supergravity is
extended by the inclusion of a supersymmetric Riemann tensor squared invariant.
Both the original model as well as the Riemann tensor squared invariant are
formulated off-shell and consequently the total action is off-shell invariant
without modification of the supersymmetry transformation rules. In this
formulation, superconformal techniques, in which the dilaton Weyl multiplet
plays a crucial role, are used. It is found that the gauging of the U(1)
R-symmetry in the presence of the higher-order derivative terms does not modify
the positive exponential in the dilaton potential. Moreover, the supersymmetric
Minkowski(4) x S^2 compactification of the original model, without the
higher-order derivatives, is remarkably left intact. It is shown that the model
also admits non-supersymmetric vacuum solutions that are direct product spaces
involving de Sitter spacetimes and negative curvature internal spaces.Comment: 32 pages; typos corrected, footnote in conclusions section adde
Ultrafast time-resolved spectroscopy of 1D metal-dielectric photonic crystals
We study the all-optical switching behavior of one-dimensional
metal-dielectric photonic crystals due to the nonlinearity of the free metal
electrons. A polychromatic pump-probe setup is used to determine the wavelength
and pump intensity dependence of the ultrafast transmission suppression as well
as the dynamics of the process on a subpicosecond timescale. We find ultrafast
(sub-picosecond) as well as a slow (millisecond) behavior. We present a model
of the ultrafast dynamics and nonlinear response which can fit the measured
data well and allows us to separate the thermal and the electronic response of
the system.Comment: 7 pages, 5 figure
Macroscopic invisibility cloaking of visible light
Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices
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