184 research outputs found
Spitzer Observations of the HII Region NGC 2467: An Analysis of Triggered Star Formation
We present new Spitzer Space Telescope observations of the region NGC 2467,
and use these observations to determine how the environment of an HII region
affects the process of star formation. Our observations comprise IRAC (3.6,
4.5, 5.8, and 8.0 um) and MIPS (24 um) maps of the region, covering
approximately 400 square arcminutes. The images show a region of ionized gas
pushing out into the surrounding molecular cloud, powered by an O6V star and
two clusters of massive stars in the region. We have identified as candidate
Young Stellar Objects (YSOs) 45 sources in NGC 2467 with infrared excesses in
at least two mid-infrared colors. We have constructed color-color diagrams of
these sources and have quantified their spatial distribution within the region.
We find that the YSOs are not randomly distributed in NGC 2467; rather, over
75% of the sources are distributed at the edge of the HII region, along
ionization fronts driven by the nearby massive stars. The high fraction of YSOs
in NGC 2467 that are found in proximity to gas that has been compressed by
ionization fronts supports the hypothesis that a significant fraction of the
star formation in NGC 2467 is triggered by the massive stars and the expansion
of the HII region. At the current rate of star formation, we estimate at least
25-50% of the total population of YSOs formed by this process.Comment: Accepted to the Astrophysical Journal, set to appear in Volume 701;
18 pages, 13 figures, 4 tables. This version reflects a few major changes
made in the accepted version, including new figure
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Investigation of the in-vitro loading on an artificial spinal disk prosthesis
Spinal diseases imposes considerable burden to both patients and society. In recent years, much surgical efforts have been made in advancing the treatment of neck and back pain. Of particular prominence is the increasing clinical acceptance and use of intervertebral artificial disk prosthesis for the treatment of discogenic back pain. Despite this increased use of such disks, their in-vivo monitoring remains rudimentary. In an effort to develop an intelligent artificial spinal disk where the in-vivo loading of the spine can by studied for the first time an experimental set up has been created in order to initially study the in-vitro loading on an artificial disc prosthesis. Eight strain gauges and two piezoresistive sensors were used and placed suitably in the artificial disk prosthesis. The results from the in-vitro loading showed linear relationship between loading and the outputs from the sensors with good repeatability and less hysteresis
Angular Momentum Evolution in Dark Matter Halos
We have analyzed high resolution N-body simulations of dark matter halos,
focusing specifically on the evolution of angular momentum. We find that not
only is individual particle angular momentum not conserved, but the angular
momentum of radial shells also varies over the age of the Universe by up to
factors of a few. We find that torques from external structure are the most
likely cause for this distribution shift. Since the model of adiabatic
contraction that is often applied to model the effects of galaxy evolution on
the dark-matter density profile in a halo assumes angular momentum
conservation, this variation implies that there is a fundamental limit on the
possible accuracy of the adiabatic contraction model in modeling the response
of DM halos to the growth of galaxies.Comment: 16 pages, 9 figures, accepted for publication in MNRA
Satellite galaxies in hydrodynamical simulations of Milky Way sized galaxies
Collisionless simulations of the CDM cosmology predict a plethora of dark
matter substructures in the halos of Milky Way sized galaxies, yet the number
of known luminous satellites galaxies is very much smaller, a discrepancy that
has become known as the `missing satellite problem'. The most massive
substructures have been shown to be plausibly the hosts of the brightest
satellites, but it remains unclear which processes prevent star formation in
the many other, purely dark substructures. We use high-resolution hydrodynamic
simulations of the formation of Milky Way sized galaxies in order to test how
well such self-consistent models of structure formation match the observed
properties of the Galaxy's satellite population. For the first time, we include
in such calculations feedback from cosmic rays injected into the star forming
gas by supernovae as well as the energy input from supermassive black holes
growing at the Milky Way's centre and its progenitor systems. We find that
non-thermal particle populations quite strongly suppress the star formation
efficiency of the smallest galaxies. In fact, our cosmic ray model is able to
reproduce the observed faint-end of the satellite luminosity function, while
models that include only the effects of cosmic reionization, or galactic winds,
do significantly worse. Our simulated satellite population approximately
matches available kinematic data on the satellites and their observed spatial
distribution. We conclude that a proper resolution of the missing satellite
problem likely requires the inclusion of non-standard physics for regulating
star formation in the smallest halos, and that cosmic reionization alone may
not be sufficient.Comment: 20 pages, 17 figure
Long-term benefits of omalizumab in a patient with severe non-allergic asthma
<p>Abstract</p> <p>Introduction</p> <p>Currently, omalizumab is indicated for the treatment of patients with severe allergic uncontrolled asthma despite optimal therapy.</p> <p>Case presentation</p> <p>We studied a 52-year-old man who has been suffering from severe non allergic steroid-resistant asthma with increased levels of total IgE and a lot of comorbidity. After a 3 years long treatment with omalizumab, he presented a significant improvement in disease control in terms of hospitalizations, exacerbation, quality of life and lung function with good safety profile.</p> <p>Conclusion</p> <p>Our case shows, after a long follow-up, how omalizumab can be effective in a severe form of non-atopic asthma. It is therefore hoped that further studies can identify indicators that are able to give to clinicians information about patients who can be responsive to monoclonal anti-IgE antibody even if non allergic.</p
âIs it essential that a steamship companyâs posters must have a ship?â The shortcomings of British shipping posters c.1840 to c.1970
Purpose: The purpose of this paper is to explore the nature of marketing communications of British shipping lines in the period from c.1840 to c.1970 to establish the extent to which these outputs reflect extant scholarship which points to the lack of innovation as a key reason for the demise of these lines.
Design/methodology/approach: The research is built on a survey of >450 posters plotting the shifting nature of advertising messages over this long period in response to the market. This is supported by reading trade press contemporary to the period to establish broader trends in marketing and whether this product sector was aberrant.
Findings: What is revealed is a generally static response in the promotion of British shipping lines throughout the timeframe, at odds with trends elsewhere. What stands out is the widespread criticism of the time singling out the shipping poster. This suggests an advanced appreciation of the role of the poster and the effectiveness of promotional messages focussing on emotions- versus a product-centred approach.
Originality/value: Whilst there is an established literature which suggests that the British merchant marine was hamstrung by a pattern of family ownership making adaptation slow, no research to date has expressly read marketing as a window onto that culture. This paper shows that whilst there may have been change within the sector which these British shipping lines responded to, when it came to presenting themselves in public via their communications strategy, they adopted a staid, conservative approach. British shipping lines, throughout the period, had a very fixed idea about who they were and what best represented their business irrespective of dramatic shifts in attitudes concerning how best to reach consumers. Interrogating promotional material, and particularly the ubiquitous shipping poster, provides another insight into the conservative and debilitating corporate culture of British shipping
Region-Specific Microstructure in the Neonatal Ventricles of a Porcine Model
© 2018, Biomedical Engineering Society. The neonate transitions from placenta-derived oxygen, to supply from the pulmonary system, moments after birth. This requires a series of structural developments to divert more blood through the right heart and onto the lungs, with the tissue quickly remodelling to the changing ventricular workload. In some cases, however, the heart structure does not fully develop causing poor circulation and inefficient oxygenation, which is associated with an increase in mortality and morbidity. This study focuses on developing an enhanced knowledge of the 1-day old heart, quantifying the region-specific microstructural parameters of the tissue. This will enable more accurate mathematical and computational simulations of the young heart. Hearts were dissected from 12, 1-day-old deceased Yorkshire piglets (mass: 2.1â2.4kg, length: 0.38â0.51m), acquired from a breeding farm. Evans blue dye was used to label the heart equator and to demarcate the left and right ventricle free walls. Two hearts were used for three-dimensional diffusion-tensor magnetic resonance imaging, to quantify the fractional anisotropy (FA). The remaining hearts were used for two-photon excited fluorescence and second-harmonic generation microscopy, to quantify the cardiomyocyte and collagen fibril structures within the anterior and posterior aspects of the right and left ventricles. FA varied significantly across both ventricles, with the greatest in the equatorial region, followed by the base and apex. The FA in each right ventricular region was statistically greater than that in the left. Cardiomyocyte and collagen fibre rotation was greatest in the anterior wall of both ventricles, with less dispersion when compared to the posterior walls. In defining these key parameters, this study provides a valuable insight into the 1-day-old heart that will provide a valuable platform for further investigation the normal and abnormal heart using mathematical and computational models
Student politics, teaching politics, black politics: an interview with Ansel Wong
Ansel Wong is the quiet man of British black politics, rarely in the limelight and never seeking political office. And yet his âcareerâ here â from Black Power firebrand to managing a multimillion budget as head of the Greater London Councilâs Ethnic Minority Unit in the 1980s â spells out some of the most important developments in black educational and cultural projects. In this interview, he discusses his identification with Pan-Africanism, his involvement in student politics, his role in the establishment of youth projects and supplementary schools in the late 1960s and 1970s, and his involvement in black radical politics in London in the same period, all of which took place against the background of revolutionary ferment in the Third World and the world of ideas, and were not without their own internal class and ethnic conflicts
First measurement of quasi-elastic baryon production in muon anti-neutrino interactions in the MicroBooNE detector
We present the first measurement of the cross section of Cabibbo-suppressed
baryon production, using data collected with the MicroBooNE detector
when exposed to the neutrinos from the Main Injector beam at the Fermi National
Accelerator Laboratory. The data analyzed correspond to
protons on target of neutrino mode running and protons on
target of anti-neutrino mode running. An automated selection is combined with
hand scanning, with the former identifying five candidate production
events when the signal was unblinded, consistent with the GENIE prediction of
events. Several scanners were employed, selecting between three
and five events, compared with a prediction from a blinded Monte Carlo
simulation study of events. Restricting the phase space to only
include baryons that decay above MicroBooNE's detection thresholds,
we obtain a flux averaged cross section of
cmAr, where statistical and systematic uncertainties are combined
Differential cross section measurement of charged current interactions without final-state pions in MicroBooNE
In this letter we present the first measurements of an exclusive electron
neutrino cross section with the MicroBooNE experiment using data from the
Booster Neutrino Beamline at Fermilab. These measurements are made for a
selection of charged-current electron neutrinos without final-state pions.
Differential cross sections are extracted in energy and angle with respect to
the beam for the electron and the leading proton. The differential cross
section as a function of proton energy is measured using events with protons
both above and below the visibility threshold. This is done by including a
separate selection of electron neutrino events without reconstructed proton
candidates in addition to those with proton candidates. Results are compared to
the predictions from several modern generators, and we find the data agrees
well with these models. The data shows best agreement, as quantified by
-value, with the generators that predict a lower overall cross section, such
as GENIE v3 and NuWro
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