120 research outputs found
Unidentified EGRET Sources and the Extragalactic Gamma-Ray Background
The large majority of EGRET point sources remain to this day without an
identified low-energy counterpart. Whatever the nature of the EGRET
unidentified sources, faint unresolved objects of the same class must have a
contribution to the diffuse gamma-ray background: if most unidentified objects
are extragalactic, faint unresolved sources of the same class contribute to the
background, as a distinct extragalactic population; on the other hand, if most
unidentified sources are Galactic, their counterparts in external galaxies will
contribute to the unresolved emission from these systems. Understanding this
component of the gamma-ray background, along with other guaranteed
contributions from known sources, is essential in any attempt to use gamma-ray
observations to constrain exotic high-energy physics. Here, we follow an
empirical approach to estimate whether a potential contribution of unidentified
sources to the extragalactic gamma-ray background is likely to be important,
and we find that it is. Additionally, we comment on how the anticipated GLAST
measurement of the diffuse gamma-ray background will change, depending on the
nature of the majority of these sources.Comment: 6 pages, 3 figures, to appear in proceedings of "The Multi-Messenger
Approach to High Energy Gamma-Ray Sources", Barcelona, 4-7 July 2006;
comments welcom
Local Void vs Dark Energy: Confrontation with WMAP and Type Ia Supernovae
It is now a known fact that if we happen to be living in the middle of a
large underdense region, then we will observe an "apparent acceleration", even
when any form of dark energy is absent. In this paper, we present a "Minimal
Void" scenario, i.e. a "void" with minimal underdensity contrast (of about
-0.4) and radius (~ 200-250 Mpc/h) that can, not only explain the supernovae
data, but also be consistent with the 3-yr WMAP data. We also discuss
consistency of our model with various other measurements such as Big Bang
Nucleosynthesis, Baryon Acoustic Oscillations and local measurements of the
Hubble parameter, and also point out possible observable signatures.Comment: Minor numerical errors and typos corrected, references adde
Indications and outcomes of enucleation versus formal pancreatectomy for pancreatic neuroendocrine tumors
Background: Pancreatoduodenectomy (PD) or distal pancreatectomy (DP) are common procedures for patients with a pancreatic neuroendocrine tumor (pNET). Nevertheless, certain patients may benefit from a pancreas-preserving resection such as enucleation (EN). The aim of this study was to define the indications and differences in long-term outcomes among patients undergoing EN and PD/DP. Methods: Patients undergoing resection of a pNET between 1992 and 2016 were identified. Indications and outcomes were evaluated, and propensity score matching (PSM) analysis was performed to compare long-term outcomes between patients who underwent EN versus PD/DP. Results: Among 1034 patients, 143 (13.8%) underwent EN, 304 (29.4%) PD, and 587 (56.8%) DP. Indications for EN were small size (1.5 cm, IQR:1.0–1.9), functional tumors (58.0%) that were mainly insulinomas (51.7%). After PSM (n = 109 per group), incidence of postoperative pancreatic fistula (POPF) grade B/C was higher after EN (24.5%) compared with PD/DP (14.0%) (p = 0.049). Median recurrence-free survival (RFS) was comparable among patients who underwent EN (47 months, 95% CI:23–71) versus PD/DP (37 months, 95% CI: 33–47, p = 0.480). Conclusion: Comparable long-term outcomes were noted among patients who underwent EN versus PD/DP for pNET. The incidence of clinically significant POPF was higher after EN
The yields of r-process elements and chemical evolution of the Galaxy
The supernova yields of r-process elements are obtained as a function of the
mass of their progenitor stars from the abundance patterns of extremely
metal-poor stars on the left-side [Ba/Mg]-[Mg/H] boundary with a procedure
proposed by Tsujimoto and Shigeyama. The ejected masses of r-process elements
associated with stars of progenitor mass are infertile
sources and the SNe II with 20are the
dominant source of r-process nucleosynthesis in the Galaxy. The ratio of these
stars 20 with compared to the all massive
stars is about 18%. In this paper, we present a simple model that
describes a star's [r/Fe] in terms of the nucleosynthesis yields of r-process
elements and the number of SN II explosions. Combined the r-process yields
obtained by our procedure with the scatter model of the Galactic halo, the
observed abundance patterns of the metal-poor stars can be well reproducedComment: 7 pages, 6 figures, Accepted for publication in Astrophysics and
Space Scienc
Olber's Paradox for Superluminal Neutrinos: Constraining Extreme Neutrino Speeds at TeV-ZeV Energies with the Diffuse Neutrino Background
The only invariant speed in special relativity is c; therefore, if some
neutrinos travel at even tiny speeds above c, normal special relativity is
incomplete and any superluminal speed may be possible. I derive a limit on
superluminal neutrino speeds v >> c at high energies by noting that such speeds
would increase the size of the neutrino horizon. The increased volume of the
Universe visible leads to a brighter astrophysical neutrino background. The
nondetection of "guaranteed" neutrino backgrounds from star-forming galaxies
and ultrahigh energy cosmic rays (UHECRs) constrains v/c at TeV--ZeV energies.
I find that v/c <= 820 at 60 TeV from the nondetection of neutrinos from
star-forming galaxies. The nondetection of neutrinos from UHECRs constrains v/c
to be less than 2500 at 0.1 EeV in a pessimistic model and less than 4.6 at 4
EeV in an optimistic model. The UHECR neutrino background nondetection is
strongly inconsistent with a naive quadratic extrapolation of the OPERA results
to EeV energies. The limits apply subject to some caveats, particularly that
the expected pionic neutrino backgrounds exist and that neutrinos travel faster
than c when they pass the detector. They could be improved substantially as the
expected neutrino backgrounds are better understood and with new experimental
neutrino background limits. I also point out that extremely subluminal speeds
would result in a much smaller neutrino background intensity than expected.Comment: 13 pages, 2 figures, fixed titl
The Standard Cosmological Model
The Standard Model of Particle Physics (SMPP) is an enormously successful
description of high energy physics, driving ever more precise measurements to
find "physics beyond the standard model", as well as providing motivation for
developing more fundamental ideas that might explain the values of its
parameters. Simultaneously, a description of the entire 3-dimensional structure
of the present-day Universe is being built up painstakingly. Most of the
structure is stochastic in nature, being merely the result of the particular
realisation of the "initial conditions" within our observable Universe patch.
However, governing this structure is the Standard Model of Cosmology (SMC),
which appears to require only about a dozen parameters. Cosmologists are now
determining the values of these quantities with increasing precision in order
to search for "physics beyond the standard model", as well as trying to develop
an understanding of the more fundamental ideas which might explain the values
of its parameters. Although it is natural to see analogies between the two
Standard Models, some intrinsic differences also exist, which are discussed
here. Nevertheless, a truly fundamental theory will have to explain both the
SMPP and SMC, and this must include an appreciation of which elements are
deterministic and which are accidental. Considering different levels of
stochasticity within cosmology may make it easier to accept that physical
parameters in general might have a non-deterministic aspect.Comment: 16 pages, 2 figures, invited talk at "Theory Canada 1", June 2005,
Vancouve
Using behavior-analytic implicit tests to assess sexual interests among normal and sex-offender populations
The development of implicit tests for measuring biases and behavioral predispositions is a recent development within psychology. While such tests are usually researched within a social-cognitive paradigm, behavioral researchers have also begun to view these tests as potential tests of conditioning histories, including in the sexual domain.
The objective of this paper is to illustrate the utility of a behavioral approach to implicit testing and means by which implicit tests can be built to the standards of behavioral psychologists.
Research findings illustrating the short history of implicit testing within the experimental analysis of behavior are reviewed. Relevant parallel and overlapping research findings from the field of social cognition and on the Implicit Association Test are also outlined.
New preliminary data obtained with both normal and sex offender populations are described in order to illustrate how behavior-analytically conceived implicit tests may have potential as investigative tools for assessing histories of sexual arousal conditioning and derived stimulus associations.
It is concluded that popular implicit tests are likely sensitive to conditioned and derived stimulus associations in the history of the test-taker rather than 'unconscious cognitions', per se
Controle associado de Alphitobius diaperinuse efeito de microrganismos eficazes no desenvolvimento de Beauveria bassiana
O objetivo deste trabalho foi avaliar a eficiência de Beauveria bassiana (Bb), terra diatomácea (TD) e microrganismos eficazes (EM-4), associados ou não, no controle de Alphitobius diaperinus, e o efeito de EM-4 no desenvolvimento de B. bassiana. Os agentes de controle (Bb, TD e EM-4), em diferentes concentrações e combinações, foram aplicados em uma mistura de cama-de-frango e ração, em que os insetos foram acondicionados por dez dias. Avaliaram-se, in vitro: a germinação, as unidades formadoras de colônia (UFC), o crescimento vegetativo e a produtividade de conÃdios de Bb em contato com suspensão aquosa de EM-4 (1%) não filtrada e filtrada. Os maiores Ãndices de mortalidade foram observados nos tratamentos TD + Bb + EM-4 e TD + Bb, nas maiores concentrações. Verificou-se efeito não-aditivo sinérgico para TD + Bb nas três concentrações. Nos testes com EM-4 filtrado, não houve diferença em relação à testemunha quanto à germinação e à s UFC, entretanto, o crescimento vegetativo e a produtividade de conÃdios foram negativamente afetados. O uso conjunto de B. bassiana e terra diatomácea, para o manejo de populações de A. diaperinus, pode reduzir o uso de produtos quÃmicos
Driver Fusions and Their Implications in the Development and Treatment of Human Cancers.
Gene fusions represent an important class of somatic alterations in cancer. We systematically investigated fusions in 9,624 tumors across 33 cancer types using multiple fusion calling tools. We identified a total of 25,664 fusions, with a 63% validation rate. Integration of gene expression, copy number, and fusion annotation data revealed that fusions involving oncogenes tend to exhibit increased expression, whereas fusions involving tumor suppressors have the opposite effect. For fusions involving kinases, we found 1,275 with an intact kinase domain, the proportion of which varied significantly across cancer types. Our study suggests that fusions drive the development of 16.5% of cancer cases and function as the sole driver in more than 1% of them. Finally, we identified druggable fusions involving genes such as TMPRSS2, RET, FGFR3, ALK, and ESR1 in 6.0% of cases, and we predicted immunogenic peptides, suggesting that fusions may provide leads for targeted drug and immune therapy
- …