1,180 research outputs found
A radio study of the superwind galaxy NGC1482
We present multifrequency radio continuum as well as HI observations of the
superwind galaxy NGC1482, with both the GMRT and the VLA. This galaxy has a
remarkable hourglass-shaped optical emission line outflow as well as bi-polar
soft X-ray bubbles on opposite sides of the galactic disk. The low-frequency,
lower-resolution radio observations show a smooth structure. From the
non-thermal emission, we estimate the available energy in supernovae, and
examine whether this would be adequate to drive the observed superwind outflow.
The high-frequency, high-resolution radio images of the central starburst
region located at the base of the superwind bi-cone shows one prominent peak
and more extended emission with substructure. This image has been compared with
the infrared, optical red-continuum, H_alpha, and, soft and hard X-ray images
from Chandra. The peak of infrared emission is the only feature which is
coincident with the prominent radio peak, and possibly defines the centre of
the galaxy. The HI observations with the GMRT show two blobs of emission on
opposite sides of the central region. These are rotating about the centre of
the galaxy and are located at ~2.4 kpc from it. In addition, these observations
also reveal a multicomponent HI-absorption profile against the central region
of the radio source, with a total width of ~250 km/s. The extreme blue- and
red-shifted absorption components are at 1688 and 1942 km/s respectively, while
the peak absorption is at 1836 km/s. This is consistent with the heliocentric
systemic velocity of 1850+/-20 km/s, estimated from a variety of observations.
We discuss possible implications of these results.Comment: 11 pages, 10 figures, 4 tables, accepted for publication in MNRA
Very Cold Gas and Dark Matter
We have recently proposed a new candidate for baryonic dark matter: very cold
molecular gas, in near-isothermal equilibrium with the cosmic background
radiation at 2.73 K. The cold gas, of quasi-primordial abundances, is condensed
in a fractal structure, resembling the hierarchical structure of the detected
interstellar medium.
We present some perspectives of detecting this very cold gas, either directly
or indirectly. The H molecule has an "ultrafine" structure, due to the
interaction between the rotation-induced magnetic moment and the nuclear spins.
But the lines fall in the km domain, and are very weak. The best opportunity
might be the UV absorption of H in front of quasars. The unexpected cold
dust component, revealed by the COBE/FIRAS submillimetric results, could also
be due to this very cold H gas, through collision-induced radiation, or
solid H grains or snowflakes. The -ray distribution, much more
radially extended than the supernovae at the origin of cosmic rays
acceleration, also points towards and extended gas distribution.Comment: 16 pages, Latex pages, crckapb macro, 3 postscript figures, uuencoded
compressed tar file. To be published in the proceeedings of the
"Dust-Morphology" conference, Johannesburg, 22-26 January, 1996, D. Block
(ed.), (Kluwer Dordrecht
Diffuse Gamma Rays: Galactic and Extragalactic Diffuse Emission
"Diffuse" gamma rays consist of several components: truly diffuse emission
from the interstellar medium, the extragalactic background, whose origin is not
firmly established yet, and the contribution from unresolved and faint Galactic
point sources. One approach to unravel these components is to study the diffuse
emission from the interstellar medium, which traces the interactions of high
energy particles with interstellar gas and radiation fields. Because of its
origin such emission is potentially able to reveal much about the sources and
propagation of cosmic rays. The extragalactic background, if reliably
determined, can be used in cosmological and blazar studies. Studying the
derived "average" spectrum of faint Galactic sources may be able to give a clue
to the nature of the emitting objects.Comment: 32 pages, 28 figures, kapproc.cls. Chapter to the book "Cosmic
Gamma-Ray Sources," to be published by Kluwer ASSL Series, Edited by K. S.
Cheng and G. E. Romero. More details can be found at
http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm
Fast Room-Temperature Detection of Terahertz Quantum Cascade Lasers with Graphene-Loaded Bow-Tie Plasmonic Antenna Arrays
We present a fast room-temperature terahertz detector based on interdigitated bow-tie antennas contacting graphene. Highly efficient photodetection was achieved by using two metals with different work functions as the arms of a bow-tie antenna contacting graphene. Arrays of the bow-ties were fabricated in order to enhance the responsivity and coupling of the incoming light to the detector, realizing an efficient imaging system. The device has been characterized and tested with a terahertz quantum cascade laser emitting in single frequency around 2 THz, yielding a responsivity of ∼34 μA/W and a noise-equivalent power of ∼1.5 × 10 W/Hz.R.D., Y.R., and H.E.B. acknowledge financial support from the Engineering and Physical Sciences Research Council (Grant No. EP/J017671/1, Coherent Terahertz Systems). S.H. acknowledges funding from EPSRC (Grant No. EP/K016636/1, GRAPHTED). H.L. and J.A.Z. acknowledge financial support from the EPSRC (Grant No. EP/L019922/1). J.A.A.-W. acknowledges a Research Fellowship from Churchill College, Cambridge. H.J.J. thanks the Royal Commission for the Exhibition of 1851 for her Research Fellowship.This is the final version of the article. It first appeared from American Chemical Society via https://doi.org/10.1021/acsphotonics.6b0040
Quarkonium production in high energy proton-proton and proton-nucleus collisions
We present a brief overview of the most relevant current issues related to
quarkonium production in high energy proton-proton and proton-nucleus
collisions along with some perspectives. After reviewing recent experimental
and theoretical results on quarkonium production in pp and pA collisions, we
discuss the emerging field of polarisation studies. Thereafter, we report on
issues related to heavy-quark production, both in pp and pA collisions,
complemented by AA collisions. To put the work in a broader perspective, we
emphasize the need for new observables to investigate quarkonium production
mechanisms and reiterate the qualities that make quarkonia a unique tool for
many investigations in particle and nuclear physics.Comment: Overview for the proceedings of QUARKONIUM 2010: Three Days Of
Quarkonium Production in pp and pA Collisions, 29-31 July 2010, Palaiseau,
France; 34 pages, 30 figures, Late
Protective effect of stromal Dickkopf-3 in prostate cancer: opposing roles for TGFBI and ECM-1
Aberrant transforming growth factor–β (TGF-β) signaling is a hallmark of the stromal microenvironment in cancer. Dickkopf-3 (Dkk-3), shown to inhibit TGF-β signaling, is downregulated in prostate cancer and upregulated in the stroma in benign prostatic hyperplasia, but the function of stromal Dkk-3 is unclear. Here we show that DKK3 silencing in WPMY-1 prostate stromal cells increases TGF-β signaling activity and that stromal cellconditioned media inhibit prostate cancer cell invasion in a Dkk-3-dependent manner. DKK3 silencing increased the level of the cell-adhesion regulator TGF-β–induced protein (TGFBI) in stromal and epithelial cell-conditioned media, and recombinant TGFBI increased prostate cancer cell invasion. Reduced expression of Dkk-3 in patient tumors was associated with increased expression of TGFBI. DKK3 silencing reduced the level of extracellular matrix protein-1 (ECM-1) in prostate stromal cell-conditioned media but increased it in epithelial cell-conditioned media, and recombinant ECM-1 inhibited TGFBI-induced prostate cancer cell invasion. Increased ECM1 and DKK3 mRNA expression in prostate tumors was associated with increased relapse-free survival. These observations are consistent with a model in which the loss of Dkk-3 in prostate cancer leads to increased secretion of TGFBI and ECM-1, which have tumor-promoting and tumor-protective roles, respectively. Determining how the balance between the opposing roles of extracellular factors influences prostate carcinogenesis will be key to developing therapies that target the tumor microenvironment
Entre Kierkegaard e Heidegger: uma reflexão sobre o sentido da angústia
This paper aims to suggest some points of convergence and distinction between the meaning that Kierkegaard assigns to anxiety in the oeuvre The concept of anxiety, and the way Heidegger addresses the same concept through the undertaking of existential analytic in Being and time. Although it may be possible to suggest undeniable similarities in the way both authors understand the phenomenon of anxiety, some distinctions may be set if well analyzed the context in which both thinkers addressed the subject. Whereas Kierkegaard understands anxiety related to sin, faith and freedom, Heidegger attributes to the phenomenon of anxiety an ontological meaning, inscribed in the project of a fundamental ontology, from which becomes possible for Dasein the freedom to choose itself, and thus assume the proper way of being.O presente trabalho tem como objetivo central indicar alguns pontos de aproximação e distinção entre o sentido atribuído por Kierkegaard à angústia na obra O conceito de angústia, e o modo pelo qual Heidegger aborda tal conceito no âmbito da analítica existencial desenvolvida em Ser e tempo. Muito embora seja possível apontar inegáveis semelhanças no modo pelo qual os dois autores compreendem o fenômeno da angústia, algumas distinções podem ser feitas se analisados os contextos a partir dos quais os pensadores se ocuparam do tema em questão. Enquanto que para Kierkegaard a angústia é vista em estrita relação com o pecado, a fé e a liberdade, Heidegger busca atribuir ao fenômeno do angustiar-se um sentido ontológico, inscrito no projeto da ontologia fundamental, a partir do qual torna-se possível ao Dasein ser livre para escolher a si mesmo, e assim assumir o modo próprio de ser
Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo
We use data from the second science run of the LIGO gravitational-wave
detectors to search for the gravitational waves from primordial black hole
(PBH) binary coalescence with component masses in the range 0.2--.
The analysis requires a signal to be found in the data from both LIGO
observatories, according to a set of coincidence criteria. No inspiral signals
were found. Assuming a spherical halo with core radius 5 kpc extending to 50
kpc containing non-spinning black holes with masses in the range 0.2--, we place an observational upper limit on the rate of PBH coalescence
of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.
Strategic planning as the intentional production of a “Trading Zone”
For a long period of time there has been a kind of mirroring between the development of decision making models in Political science and the concepts and paradigms used in Planning theory. The dialogue has been interrupted when the "Garbage Can" model was proposed by Choen, March and Olsen in 1972: a model that emphasized the irreducible complexity of the policy processes. The article reconstructs this relationship and its evolution showing the influence of decision-making models on planning theory, and showing the difficulties of managing complexity for planners. The paper holds that interpreting planning processes through the lens of the "Trading zone" concept proposed by Peter Galison in the field of history of science could be an interesting way of dealing with the extreme complexity of contemporary planning problems. The conclusion is that the use of the Trading Zone concept is very promising to solve some dilemmas of planning theory and that it is particularly useful if we employ it in the growing area of strategic spatial planning
Kinome rewiring reveals AURKA limits PI3K-pathway inhibitor efficacy in breast cancer.
Dysregulation of the PI3K-AKT-mTOR signaling network is a prominent feature of breast cancers. However, clinical responses to drugs targeting this pathway have been modest, possibly because of dynamic changes in cellular signaling that drive resistance and limit drug efficacy. Using a quantitative chemoproteomics approach, we mapped kinome dynamics in response to inhibitors of this pathway and identified signaling changes that correlate with drug sensitivity. Maintenance of AURKA after drug treatment was associated with resistance in breast cancer models. Incomplete inhibition of AURKA was a common source of therapy failure, and combinations of PI3K, AKT or mTOR inhibitors with the AURKA inhibitor MLN8237 were highly synergistic and durably suppressed mTOR signaling, resulting in apoptosis and tumor regression in vivo. This signaling map identifies survival factors whose presence limits the efficacy of targeted therapies and reveals new drug combinations that may unlock the full potential of PI3K-AKT-mTOR pathway inhibitors in breast cancer
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