876 research outputs found
Star-formation in the central kpc of the starburst/LINER galaxy NGC1614
A high angular resolution, multi-wavelength study of the LINER galaxy NGC1614
has been carried out. OVRO CO 1-0 observations are presented together with
extensive multi-frequency radio continuum and HI absorption observations with
the VLA and MERLIN. Toward the center of NGC1614, we have detected a ring of
radio continuum emission with a radius of 300 pc. This ring is coincident with
previous radio and Paschen-alpha observations. The dynamical mass of the ring
based on HI absorption is 3.1 x 10E9 Msun. The peak of the integrated CO 1-0
emission is shifted by 1" to the north-west of the ring center and a
significant fraction of the CO emission is associated with a crossing dust
lane. An upper limit to the molecular gas mass in the ring region is 1.7 x 10E9
Msun. Inside the ring, there is a north to south elongated 1.4GHz radio
continuum feature with a nuclear peak. This peak is also seen in the 5GHz radio
continuum and in the CO. We suggest that the R=300 pc star forming ring
represents the radius of a dynamical resonance - as an alternative to the
scenario that the starburst is propagating outwards from the center into a
molecular ring. The ring-like appearance probably part of a spiral structure.
Substantial amounts of molecular gas have passed the radius of the ring and
reached the nuclear region. The nuclear peak seen in 5GHz radio continuum and
CO is likely related to previous star formation, where all molecular gas was
not consumed. The LINER-like optical spectrum observed in NGC1614 may be due to
nuclear starburst activity, and not to an Active Galactic Nucleus (AGN).
Although the presence of an AGN cannot be excluded.Comment: Accepted by Astronomy and Astrophysics, 12 pages, 10 figure
Compact steep-spectrum sources from the S4 sample
We present the results of 5-GHz observations with the VLA A-array of a sample
of candidate Compact Steep Spectrum sources (CSSs) selected from the S4 survey.
We also estimate the symmetry parameters of high-luminosity CSSs selected from
different samples of radio sources, and compare these with the larger sources
of similar luminosity to understand their evolution and the consistency of the
CSSs with the unified scheme for radio galaxies and quasars. The majority of
CSSs are likely to be young sources advancing outwards through a dense
asymmetric environment. The radio properties of CSSs are found to be consistent
with the unified scheme, in which the axes of the quasars are observed close to
the line of sight, while radio galaxies are observed close to the plane of the
sky.Comment: accepted for publication in mnras; 8 pages, figure 1 with 21 images,
and two additional figures; 2 table
Radiation testing of composite materials, in situ versus ex situ effects
The effect of post irradiation test environments on tensile properties of representative advanced composite materials (T300/5208, T300/934, C6000/P1700) was investigated. Four ply (+ or - 45 deg/+ or - 45 deg) laminate tensile specimens were exposed in vacuum up to a bulk dose of 1 x 10 to the 10th power rads using a mono-energetic fluence of 700 keV electrons from a Van de Graaff accelerator. Post irradiation testing was performed while specimens were being irradiated (in situ data), in vacuum after cessation of irradiation (in vacuo data), and after exposure to air (ex situ data). Room temperature and elevated temperature effects were evaluated. The radiation induced changes to the tensile properties were small. Since the absolute changes in tensile properties were small, the existance of a post irradiation test environment effect was indeterminate
VLA Observations of H I in the Helix Nebula (NGC 7293)
We report the detection of 21-cm line emission from H I in the planetary
nebula NGC 7293 (the Helix). The observations, made with the Very Large Array,
show the presence of a ring of atomic hydrogen that is associated with the
outer portion of the ionized nebula. This ring is most probably gas ejected in
the AGB phase that has been subsequently photodissociated by radiation from the
central star. The H I emission spreads over about 50 km/s in radial velocity.
The mass in H I is approximately 0.07 solar masses, about three times larger
than the mass in molecular hydrogen and comparable with the mass in ionized
hydrogen.Comment: 19 pages, 9 figure
The benefits of reducing anxiety in a Podiatric Surgical Unit in the UK with Midazolam
La sedación se ha utilizado con frecuencia junto a muchas de las intervenciones quirúrgicas realizadas bajo anestésicos locales (AL) . En la cirugía podológica, hay una escasez de literatura sobre los efectos de la sedación ante las señales fisiológicas de los pacientes. La anestesia general se practica con mayor frecuencia que la sedación con anestésico local en podología . El objetivo de esta estudioa fue analizar la presión arterial ( PA) y frecuencia cardiaca (FC ) en contra de la administración de midazolam. Se realizó una evaluación retrospectiva de las registros de sedación antes de los procedimientos de podología llevadas a cabo durante los años 2008/2009 . La PA ( sistólica / diastólica mm de Hg ) y la FC ( latidos / min ) se registraron antes de la administración de midazolam y durante los primeros 30 minutos después de la administración . Noventa y cuatro pacientes ( 74 mujeres, 20 hombres) fueron ingresados para cirugía podológica . Se realizaron Noventa y nueve intervenciones , con cinco de los sujetos sometidos a dos procedimientos. La edad media fue de 59 ± 13,5 años ( 21-87 ) y la dosis media de midazolam administrado fue 2,8 ± 1,3 mg ( 0,5-8 ) . La media de la PA antes de administrar midazolam fue de 148 /85 mmHg y la FC 80. A los 30 minutos la PA era de 136 /80 y la FC 71 . La PA y la FC fueron significativamente diferentes con una p < 0,001 para la lectura antes de la administración. Los resultados presentados indican el uso de este fármaco junto con el anestesico local en un contexto de sedación tiene resultados favorables.Sedation has been frequently used alongside many surgical interventions under local anaesthetics (LA). In podiatric surgery, there is a paucity of literature on the effects of sedation drugs on surrogate measures of patients’ physiological signs. General anaesthetic is practised more frequently than sedation assisted local anaesthetic in podiatry. The aim of this audit was to analyse blood pressure (BP) and heart rate (HR) against the administration of midazolam. A retrospective assessment of sedation notes prior to podiatric procedures undertaken during the years 2008/2009 was performed. BP (systolic/diastolic mm Hg) and heart rate (beats/min) were recorded prior to the administration of midazolam and for the first 30 minutes following administration. Ninety-four consecutive patients (74 women, 20 men) were admitted for podiatric surgery. Ninety-nine interventions were performed, with five of the subjects undergoing two procedures. The mean age was 59±13.5 years (21-87) and average midazolam administered 2.8±1.3 mg (0.5-8). Average BP prior to midazolam was 148/85 mm Hg and HR 80. At 30 minutes assessment BP was 136/80 and HR 71. BP and HR differences were significantly different at p<0.001 to the reading prior to administration. The results presented indicate the use of such a drug as an adjunct to LA in a sedation context has favourable results
Bunge’s Mathematical Structuralism Is Not a Fiction
In this paper, I explore Bunge’s fictionism in philosophy of mathematics. After an overview of Bunge’s views, in particular his mathematical structuralism, I argue that the comparison between mathematical objects and fictions ultimately fails. I then sketch a different ontology for mathematics, based on Thomasson’s metaphysical work. I conclude that mathematics deserves its own ontology, and that, in the end, much work remains to be done to clarify the various forms of dependence that are involved in mathematical knowledge, in particular its dependence on mental/brain states and material objects
Monitoring of the prompt radio emission from the unusual supernova 2004dj in NGC2403
Supernova 2004dj in the nearby spiral galaxy NGC2403 was detected optically
in July 2004. Peaking at a magnitude of 11.2, this is the brightest supernova
detected for several years. Here we present Multi-Element Radio Linked
Interferometer Network (MERLIN) observations of this source, made over a four
month period, which give a position of R.A. = 07h37m17.044s, Dec
=+65deg35'57.84" (J2000.0). We also present a well-sampled 5 GHz light curve
covering the period from 5 August to 2 December 2004. With the exception of the
unusual and very close SN 1987A, these observations represent the first
detailed radio light curve for the prompt emission from a Type II-P supernova.Comment: (1) Jodrell Bank Observatory (2) University of Valencia (3)
University of Sheffield 6 pages, 1 figure. To appear in ApJ letter
Prevalence and co-infection of Toxoplasma gondii and Neospora caninum in Apodemus sylvaticus in an area relatively free of cats
The protozoan parasite Toxoplasma gondii is prevalent worldwide and can infect a remarkably wide range of hosts despite
felids being the only definitive host. As cats play a major role in transmission to secondary mammalian hosts, the interaction
between cats and these hosts should be a major factor determining final prevalence in the secondary host. This study
investigates the prevalence of T. gondii in a natural population of Apodemus sylvaticus collected from an area with low cat
density (<2·5 cats/km2). A surprisingly high prevalence of 40·78% (95% CI: 34·07%–47·79%) was observed despite this.
A comparable level of prevalence was observed in a previously published study using the same approaches where a
prevalence of 59% (95% CI: 50·13%–67·87%) was observed in a natural population of Mus domesticus from an area with high
cat density (>500 cats/km2). Detection of infected foetuses frompregnant dams in both populations suggests that congenital
transmission may enable persistence of infection in the absence of cats. The prevalences of the related parasite, Neospora
caninum were found to be low in both populations (A. sylvaticus: 3·39% (95% CI: 0·12%–6·66%); M. domesticus: 3·08%
(95% CI: 0·11%–6·05%)). These results suggest that cat density may have a lower than expected effect on final prevalence in
these ecosystems
FIRST-based survey of Compact Steep Spectrum sources, II. MERLIN and VLA observations of Medium-sized Symmetric Objects
A new sample of candidate Compact Steep Spectrum (CSS) sources that are much
weaker than the CSS source prototypes has been selected from the VLA FIRST
catalogue. MERLIN `snapshot' observations of the sources at 5 GHz indicate that
six of them have an FR II-like morphology, but are not edge-brightened as is
normal for Medium-sized Symmetric Objects (MSOs) and FR IIs. Further
observations of these six sources with the VLA at 4.9 GHz and MERLIN at 1.7
GHz, as well as subsequent full-track observations with MERLIN at 5 GHz of what
appeared to be the two sources of greatest interest are presented. The results
are discussed with reference to the established evolutionary model of CSS
sources being young but in which not all of them evolve to become old objects
with extended radio structures. A lack of stable fuelling in some of them may
result in an early transition to a so-called coasting phase so that they fade
away instead of growing to become large-scale objects. It is possible that one
of the six sources (1542+323) could be labelled as a prematurely `dying' MSO or
a `fader'.Comment: 13 pages, matches the version printed in Astronomy & Astrophysic
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