3,534 research outputs found
Discovery of CH and OH in the -513 km s-1 Ejecta of Eta Carinae
The very massive star, Eta Carinae, is enshrouded in an unusual complex of
stellar ejecta, which is highly depleted in C and O, and enriched in He and N.
This circumstellar gas gives rise to distinct absorption components
corresponding to at least 20 different velocities along the line-of-sight. The
velocity component at -513 kms-1 exhibits very low ionization with
predominantly neutral species of iron-peak elements. Our statistical
equilibrium/photoionization modeling indicates that the low temperature (T =
760 K) and high density (n_H=10^7 cm^-3) of the -513 kms-1 component is
conducive to molecule formation including those with the elements C and O.
Examination of echelle spectra obtained with the Space Telescope Imaging
Spectrograph (STIS) aboard the confirms the model's predictions. The molecules,
H_2, CH, and most likely OH, have been identified in the -513 kms-1 absorption
spectrum. This paper presents the analysis of the HST/STIS spectra with the
deduced column densities for CH, OH and C I, and upper limit for CO. It is
quite extraordinary to see molecular species in a cool environment at such a
high velocity. The sharp molecular and ionic absorptions in this extensively
CNO- processed material offers us a unique environment for studying the
chemistry, dust formation processes, and nucleosynthesis in the ejected layers
of a highly evolved massive star.Comment: tentatively scheduled for the ApJ 1 September 2005, v630, 1 issu
The Effects of Processing and Ripening on the Quality of Pizza Cheese
End of Project ReportThe main aims of this project were to quantify the changes in fuctionality during maturation of cheese and to develop an understanding of the factors which mediate the development of functionality. The approach to achieving these objectives involved the establishment of a suitable pilot plant production procedure for low moisture Mozzarella, developing and/or adapting existing methods for objective evaluation of the functional properties of pizza cheeses, and evaluating the effects of ripening and variations in cheesemaking conditions (e.g. pH at stretching) on the composition, yield and functionality of low moisture Mozzarella cheese.
The main conclusions were as follows:
The technology for developing low moisture Mozzarella cheeses, with different compositions and functionalities, via alteration of cheesemaking parameters, has been developed.
A database has been established on the storage-related changes that occur in texture, proteolysis and functionality of low moisture Mozzarella cheeses of different compositions. In addition an extensive database on the compositional, biochemical, microstructural, rheological and/or functional properties of different commerical cheeses - low moisture Mozzarella, Cheddar and analogue pizza cheese, has been compiled.
The functionality of low moisture Mozzarella changes markedly on storage/ripening at 4ÂşC. Initially, during the first 5-10 days of storage, the functionality of the baked cheese is poor but then improves on further storage as reflected by reductions in melt time and apparent viscosity (chewiness) and increases in stretchability and flowability. The changes in functionality are mediated by storage-related increases in pH, proteolysis, protein-bound water and free oil in the cheese. On prolonged storage (e.g. > 60 d at 4ÂşC), the cheese functionality becomes impaired as the shredded cheese develops an increased susceptibility to clumping/balling which makes it difficult to dispense the cheese onto the pizza pie and achieve a uniform surface distribution. Moreover, the baked cheese tends to exude excess free oil and loses its desired level of chewiness attaining a 'soupy' consistency.
Novel methods were developed/adapted to objectively quantify functionality in the raw (susceptibility of shredded cheese to clump) and cooked (stretchability, chewiness, viscoelasticity) cheeses.Department of Agriculture, Food and the Marin
Waiting in the Wings: Reflected X-ray Emission from the Homunculus Nebula
We report the first detection of X-ray emission associated with the
Homunculus Nebula which surrounds the supermassive star Eta Carinae. The
emission is characterized by a temperature in excess of 100 MK, and is
consistent with scattering of the time-delayed X-ray flux associated with the
star. The nebular emission is bright in the northwestern lobe and near the
central regions of the Homunculus, and fainter in the southeastern lobe. We
also report the detection of an unusually broad Fe K fluorescent line, which
may indicate fluorescent scattering off the wind of a companion star or some
other high velocity outflow. The X-ray Homunculus is the nearest member of the
small class of Galactic X-ray reflection nebulae, and the only one in which
both the emitting and reflecting sources are distinguishable.Comment: 17 pages, 5 figures, accepted by Ap
Detection of Gamma-ray Emission from the Eta-Carinae Region
We present the results of extensive observations by the gamma-ray AGILE
satellite of the Galactic region hosting the Carina nebula and the remarkable
colliding wind binary Eta Carinae (Eta Car) during the period 2007 July to 2009
January. We detect a gamma-ray source (1AGL J1043-5931) consistent with the
position of Eta Car. If 1AGL J1043-5931 is associated with the Eta Car system
our data provide the long sought first detection above 100 MeV of a colliding
wind binary. The average gamma-ray flux above 100 MeV and integrated over the
pre-periastron period 2007 July to 2008 October is F = (37 +/- 5) x 10-8 ph
cm-2 s-1 corresponding to an average gamma-ray luminosity of L = 3.4 x 10^34
erg s-1 for a distance of 2.3 kpc. We also report a 2-day gamma-ray flaring
episode of 1AGL J1043-5931 on 2008 Oct. 11-13 possibly related to a transient
acceleration and radiation episode of the strongly variable shock in the
system.Comment: 5 pages, 4 figure, accepted for publication in ApJ Letter
Menstruation as a Weapon of War – The Politics of the Bleeding Body for Women on Political Protest at Armagh Prison Northern Ireland.
This article draws on the voices of women political prisoners who were detained at Armagh Prison during the period of the Troubles or the Conflict in Northern Ireland. It focuses on women who undertook an extraordinary form of protest against the prison authorities during the 1980s, known as the No Wash Protest. As the prisoners were prevented from leaving their cells by prison officer either to wash or to use the toilet, the women, living in the midst of their own dirt and body waste, added menstrual blood as a form of protest
Biochemical and Functional Relationships in Cheese.
End of Project ReportCheese is used extensively in cooking applications, mainly because of its
flavour and heat-induced functionality, which is a composite of different
attributes such as softening, flow and stretch. The functional attributes of
cooked cheese generally have a major impact on the quality of foods in
which cheese is included as an ingredient, e.g. pizza pie. Owing to its
importance in cookery applications, numerous studies have been
undertaken on the effects of different factors on the age-related changes in
the functionality of cooked cheese, especially Mozzarella, and to a lesser
extent, Cheddar and processed cheese. These studies have shown that the
functionality of natural cheese is dynamic, with the different functional
attributes undergoing marked changes during ripening, and, for a given
cheese variety, the desired functional attributes are optimum within a
specific time frame during maturation. The time at which the cheese
becomes functional and the width of the window - and hence the functional
shelf-life, are affected by the extent of chemical changes, including the
increase in proteolysis and the ratio of bound to free moisture.
The main aims of this project were to investigate the effects of the following
on the age-related changes in heat-related functional attributes (e.g.
stretchability, fluidity) of cheese:
* fat reduction,
* the degree of fat emulsification,
* the pH and calcium content and their interaction,
* the correlation between proteolysis and functional attributes,
especially attributes other than flowability, e.g. rheological
properties of raw cheese, stretchability of heated cheese, and
* the age-related changes in the functionality of cheeses other
than Mozzarella, e.g. analogue pizza cheese and Emmental.
At the outset of this project, comparatively little information was available on
the effects of the above parameters on the age-related changes in heatinduced
functional attributes (e.g. stretchability, fluidity) of cheese,
especially for varieties other than Mozzarella.Department of Agriculture, Food and the Marin
Neurospora from natural populations: Population genomics insights into the Life history of a model microbial Eukaryote
The ascomycete filamentous fungus Neurospora crassa played a historic role in experimental biology and became a model system for genetic research. Stimulated by a systematic effort to collect wild strains initiated by Stanford geneticist David Perkins, the genus Neurospora has also become a basic model for the study of evolutionary processes, speciation, and population biology. In this chapter, we will first trace the history that brought Neurospora into the era of population genomics. We will then cover the major contributions of population genomic investigations using Neurospora to our understanding of microbial biogeography and speciation, and review recent work using population genomics and genome-wide association mapping that illustrates the unique potential of Neurospora as a model for identifying the genetic basis of (potentially adaptive) phenotypes in filamentous fungi. The advent of population genomics has contributed to firmly establish Neurospora as a complete model system and we hope our review will entice biologists to include Neurospora in their research
An equatorial wind from the massive young stellar object S140 IRS 1
The discovery of the second equatorial ionized stellar wind from a massive
young stellar object is reported. High resolution radio continuum maps of S140
IRS 1 reveal a highly elongated source that is perpendicular to the larger
scale bipolar molecular outflow. This picture is confirmed by location of a
small scale monopolar near-IR reflection nebula at the base of the blueshifted
lobe. A second epoch of observations over a five year baseline show little
ordered outward proper motion of clumps as would have been expected for a jet.
A third epoch, taken only 50 days after the second, did show significant
changes in the radio morphology. These radio properties can all be understood
in the context of an equatorial wind driven by radiation pressure from the
central star and inner disc acting on the gas in the surface layers of the disc
as proposed by Drew et al. (1998). This equatorial wind system is briefly
compared with the one in S106IR, and contrasted with other massive young
stellar objects that drive ionized jets.Comment: 19 pages, 5 figures, accepted by ApJ, minor changes in light of
referees repor
Evolution of emission line activity in intermediate mass young stars
We present optical spectra of 45 intermediate mass Herbig Ae/Be stars.
Together with the multi-epoch spectroscopic and photometric data compiled for a
large sample of these stars and ages estimated for individual stars by using
pre-main sequence evolutionary tracks, we have studied the evolution of
emission line activity in them. We find that, on average, the H_alpha emission
line strength decreases with increasing stellar age in HAeBe stars, indicating
that the accretion activity gradually declines during the PMS phase. This would
hint at a relatively long-lived (a few Myr) process being responsible for the
cessation of accretion in Herbig Ae/Be stars. We also find that the accretion
activity in these stars drops substantially by ~ 3 Myr. This is comparable to
the timescale in which most intermediate mass stars are thought to lose their
inner disks, suggesting that inner disks in intermediate mass stars are
dissipated rapidly after the accretion activity has fallen below a certain
level. We, further find a relatively tight correlation between strength of the
emission line and near-infrared excess due to inner disks in HAeBe stars,
indicating that the disks around Herbig Ae/Be stars cannot be entirely passive.
We suggest that this correlation can be understood within the frame work of the
puffed-up inner rim disk models if the radiation from the accretion shock is
also responsible for the disk heating.Comment: 39 pages, accepted for publication in Ap
- …