859 research outputs found
Constraints on the environment and energetics of the Broad-Line Ic SN2014ad from deep radio and X-ray observations
Broad-line type Ic Supernovae (BL-Ic SNe) are characterized by high ejecta
velocity ( km s) and are sometimes associated with the
relativistic jets typical of long duration ( s) Gamma-Ray Bursts
(L-GRBs). The reason why a small fraction of BL-Ic SNe harbor relativistic jets
is not known. Here we present deep X-ray and radio observations of the BL-Ic
SN2014ad extending from to days post explosion. SN2014ad was not
detected at either frequency and has no observational evidence of a GRB
counterpart. The proximity of SN2014ad ( Mpc) enables very deep
constraints on the progenitor mass-loss rate and on the total energy
of the fast ejecta . We consider two synchrotron emission scenarios for a
wind-like circumstellar medium (CSM): (i) uncollimated non-relativistic ejecta,
and (ii) off-axis relativistic jet. Within the first scenario our observations
are consistent with GRB-less BL-Ic SNe characterized by a modest energy budget
of their fast ejecta ( erg), like SNe 2002ap and 2010ay.
For jetted explosions, we cannot rule out a GRB with erg
(beam-corrected) with a narrow opening angle ()
observed moderately off-axis () and
expanding in a very low CSM density ( M
yr). Our study shows that off-axis low-energy jets expanding in a
low-density medium cannot be ruled out even in the most nearby BL-Ic SNe with
extensive deep observations, and might be a common feature of BL-Ic SNe.Comment: 9 pages, 5 figures, accepted in Ap
Intelligent Queries over BIRN Data using the Foundational Model of Anatomy and a Distributed Query-Based Data Integration System
We demonstrate the usefulness of the Foundational Model of Anatomy (FMA) ontology in reconciling different neuroanatomical parcellation schemes in order to facilitate automatic annotation and “intelligent” querying and visualization over a large multisite fMRI study of schizophrenic versus normal controls
Enabling RadLex with the Foundational Model of Anatomy Ontology to Organize and Integrate Neuro-imaging Data
In this study we focused on empowering RadLex with an ontological framework and additional content derived from the Foundational Model of Anatomy Ontology1 thereby providing RadLex the facility to correlate the different standards used in annotating neuroradiological image data. The objective of this work is to promote data sharing, data harmonization and interoperability between disparate neuroradiological labeling systems
Issues in the Design of a Pilot Concept-Based Query Interface for the Neuroinformatics Information Framework
This paper describes a pilot query interface that has been constructed to help us explore a "concept-based" approach for searching the
Neuroscience Information Framework (NIF). The query interface is
concept-based in the sense that the search terms submitted through the
interface are selected from a standardized vocabulary of terms
(concepts) that are structured in the form of an ontology. The NIF
contains three primary resources: the NIF Resource Registry, the NIF
Document Archive, and the NIF Database Mediator. These NIF resources
are very different in their nature and therefore pose challenges when
designing a single interface from which searches can be automatically
launched against all three resources simultaneously. The paper first
discusses briefly several background issues involving the use of
standardized biomedical vocabularies in biomedical information
retrieval, and then presents a detailed example that illustrates how
the pilot concept-based query interface operates. The paper concludes
by discussing certain lessons learned in the development of the current
version of the interface
The NIF LinkOut Broker: A Web Resource to Facilitate Federated Data Integration using NCBI Identifiers
This paper describes the NIF LinkOut Broker (NLB) that has been built as part of the Neuroscience Information Framework (NIF) project. The NLB is designed to coordinate the assembly of links to neuroscience information items (e.g., experimental data, knowledge bases, and software tools) that are (1) accessible via the Web, and (2) related to entries in the National Center for Biotechnology Information’s (NCBI’s) Entrez system. The NLB collects these links from each resource and passes them to the NCBI which incorporates them into its Entrez LinkOut service. In this way, an Entrez user looking at a specific Entrez entry can LinkOut directly to related neuroscience information. The information stored in the NLB can also be utilized in other ways. A second approach, which is operational on a pilot basis, is for the NLB Web server to create dynamically its own Web page of LinkOut links for each NCBI identifier in the NLB database. This approach can allow other resources (in addition to the NCBI Entrez) to LinkOut to related neuroscience information. The paper describes the current NLB system and discusses certain design issues that arose during its implementation
The lack of the Celf2a splicing factor converts a Duchenne genotype into a Becker phenotype
Substitutions, deletions and duplications in the dystrophin gene lead to either the severe Duchenne muscular dystrophy (DMD) or mild Becker muscular dystrophy depending on whether out-of-frame or in-frame transcripts are produced. We identified a DMD case (GSΔ44) where the correlation between genotype and phenotype is not respected, even if carrying a typical Duchenne mutation (exon 44 deletion) a Becker-like phenotype was observed. Here we report that in this patient, partial restoration of an in-frame transcript occurs by natural skipping of exon 45 and that this is due to the lack of Celf2a, a splicing factor that interacts with exon 45 in the dystrophin pre-mRNA. Several experiments are presented that demonstrate the central role of Celf2a in controlling exon 45 splicing; our data point to this factor as a potential target for the improvement of those DMD therapeutic treatments, which requires exon 45 skipping
Drag Reduction in Wave-Swept Macroalgae: Alternative Strategies and New Predictions
Premise of the study: Intertidal macroalgae must resist extreme hydrodynamic forces imposed by crashing waves. How does frond flexibility mitigate drag, and how does flexibility affect predictions of drag and dislodgement in the field? Methods: We characterized flexible reconfiguration of six seaweed species in a recirculating water flume, documenting both shape change and area reduction as fronds reorient. We then used a high-speed gravity-accelerated water flume to test our ability to predict drag under waves based on extrapolations of drag recorded at slower speeds. We compared dislodgement forces to drag forces predicted from slow- and high-speed data to generate new predictions of survivorship and maximum sustainable frond size along wave-swept shores. Key results: Bladed algae were generally shape changers , limiting drag by reducing drag coefficients, whereas the branched alga Calliarthron was an area reducer , limiting drag by reducing projected area in flow. Drag predictions often underestimated actual drag measurements at high speeds, suggesting that slow- speed data may not reflect the performance of flexible seaweeds under breaking waves. Several seaweeds were predicted to dislodge at similar combinations of velocity and frond size, suggesting common scaling factors of dislodgement strength and drag. Conclusions: Changing shape and reducing projected area in flow are two distinct strategies employed by flexible seaweeds to resist drag. Flexible reconfiguration contributes to the uncertainty of drag extrapolation, and researchers should use caution when predicting drag and dislodgement of seaweeds in the field
Inequivalence of QFT's on Noncommutative Spacetimes: Moyal versus Wick-Voros
In this paper, we further develop the analysis started in an earlier paper on
the inequivalence of certain quantum field theories on noncommutative
spacetimes constructed using twisted fields. The issue is of physical
importance. Thus it is well known that the commutation relations among
spacetime coordinates, which define a noncommutative spacetime, do not
constrain the deformation induced on the algebra of functions uniquely. Such
deformations are all mathematically equivalent in a very precise sense. Here we
show how this freedom at the level of deformations of the algebra of functions
can fail on the quantum field theory side. In particular, quantum field theory
on the Wick-Voros and Moyal planes are shown to be inequivalent in a few
different ways. Thus quantum field theory calculations on these planes will
lead to different physics even though the classical theories are equivalent.
This result is reminiscent of chiral anomaly in gauge theories and has obvious
physical consequences. The construction of quantum field theories on the
Wick-Voros plane has new features not encountered for quantum field theories on
the Moyal plane. In fact it seems impossible to construct a quantum field
theory on the Wick-Voros plane which satisfies all the properties needed of
field theories on noncommutative spaces. The Moyal twist seems to have unique
features which make it a preferred choice for the construction of a quantum
field theory on a noncommutative spacetime.Comment: Revised version accepted for publication in Phys.Rev.D; 18 page
O processo cumulativo de Wicksell e a dinâmica da inflação
Este artigo discute a dinâmica de inflação em termos de um enfoque de fundos emprestáveis, que enfatiza o papel da taxa de juros como variável chave no processo de ajustamento e como tal reproduz, num contexto inflacionário, algumas proposições fundamentais de Wicksell
O enfoque monetário à teoria do balanço de pagamentos. algumas implicações
Este artigo objetiva expor uma versão do chamado enfoque monetário à teoria do balanço de pagamentos e explorar algumas de suas implicações que não são claras na literatura sobre o assunto. As implicações teóricas e de política econômica do enfoque monetário contrastam, sob certos aspectos, com princípios e idéias que parecem enraizadas tanto no meio profissional quanto acadêmico, talvez fruto de longos anos de aplicação da teoria keynesiana do multiplicador aos problemas do balanço de pagamentos
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