540 research outputs found
Ultrastable lasers based on vibration insensitive cavities
We present two ultra-stable lasers based on two vibration insensitive cavity
designs, one with vertical optical axis geometry, the other horizontal.
Ultra-stable cavities are constructed with fused silica mirror substrates,
shown to decrease the thermal noise limit, in order to improve the frequency
stability over previous designs. Vibration sensitivity components measured are
equal to or better than 1.5e-11 per m.s^-2 for each spatial direction, which
shows significant improvement over previous studies. We have tested the very
low dependence on the position of the cavity support points, in order to
establish that our designs eliminate the need for fine tuning to achieve
extremely low vibration sensitivity. Relative frequency measurements show that
at least one of the stabilized lasers has a stability better than 5.6e-16 at 1
second, which is the best result obtained for this length of cavity.Comment: 8 pages 12 figure
Inelastic scattering of photoelectrons from He nanodroplets
We present a detailed study of inelastic energy-loss collisions of
photoelectrons emitted from He nanodroplets by tunable extreme ultraviolet
(XUV) radiation. Using coincidence imaging detection of electrons and ions, we
probe the lowest He droplet excited states up to the electron impact ionization
threshold. We find significant signal contributions from photoelectrons emitted
from free He atoms accompanying the He nanodroplet beam. Furthermore, signal
contributions from photoionization and electron impact excitation/ionization
occurring in pairs of nearest-neighbor atoms in the He droplets are detected.
This work highlights the importance of inelastic electron scattering in the
interaction of nanoparticles with XUV radiation
INTEGRAL observations of the Be/X-ray binary EXO 2030+375 during outburst
We present a type-I outburst of the high-mass X-ray binary EXO 2030+375,
detected during INTEGRAL's Performance and Verification Phase in December 2002
(on-source time about 10e+06 seconds). In addition, six more outbursts have
been observed during INTEGRAL's Galactic Plane Scans. X-ray pulsations have
been detected with a pulse period of 41.691798+-0.000016 s. The X-ray
luminosity in the 5-300 keV energy range was 9.7*10e+36 erg/s, for a distance
of 7.1 kpc. Two unusual features were found in the light curve, with an initial
peak before the main outburst and another possible spike after the maximum.
RXTE observations confirm only the existence of the initial spike. Although the
initial peak appears to be a recurrent feature, the physical mechanisms
producing it and the possible second spike are unknown. Moreover, a four-day
delay between periastron passage and the peak of the outburst is observed. We
present for the first time a 5-300 keV broad-band spectrum of this source. It
can be modelled by the sum of a disk black body (kT_bb~8 keV) with either a
power law model with Gamma=2.04+-0.11 keV or a Comptonized component (spherical
geometry, kT_e=30 keV, tau=2.64, kT_W=1.5 keV).Comment: 10 pages, 11 figures, to be published in A&
Consumption caught in the cash nexus.
During the last thirty years, ‘consumption’ has become a major topic in the study of contemporary culture within anthropology, psychology and sociology. For many authors it has become central to understanding the nature of material culture in the modern world but this paper argues that the concept is, in British writing at least, too concerned with its economic origins in the selling and buying of consumer goods or commodities. It is argued that to understand material culture as determined through the monetary exchange for things - the cash nexus - leads to an inadequate sociological understanding of the social relations with objects. The work of Jean Baudrillard is used both to critique the concept of consumption as it leads to a focus on advertising, choice, money and shopping and to point to a more sociologically adequate approach to material culture that explores objects in a system of models and series, ‘atmosphere’, functionality, biography, interaction and mediation
Liquid racism and the Danish Prophet Muhammad cartoons
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 The Author.This article examines reactions to the October 2005 publication of the Prophet Muhammad cartoons in the Danish newspaper Jyllands-Posten. It does so by using the concept of ‘liquid racism’. While the controversy arose because it is considered blasphemous by many Muslims to create images of the Prophet Muhammad, the article argues that the meaning of the cartoons is multidimensional, that their analysis is significantly more complex than most commentators acknowledge, and that this complexity can best be addressed via the concept of liquid racism. The article examines the liquidity of the cartoons in relation to four readings. These see the cartoons as: (1) a criticism of Islamic fundamentalism; (2) blasphemous images; (3) Islamophobic and racist; and (4) satire and a defence of freedom of speech. Finally, the relationship between postmodernity and the rise of fundamentalism is discussed because the cartoons, reactions to them, and Islamic fundamentalism, all contain an important postmodern dimension.ESR
Plant closures, precariousness and policy responses:revisiting MG Rover 10 years on
With automotive plants being closed in Australia and western Europe, this article reflects on the employment status of ex-MG Rover (MGR) workers following the closure of the Longbridge plant in 2005. In particular, it draws on Standing's typology of labour market insecurity and uses a mixed-methods approach including an analysis of a longitudinal survey of some 200 ex-MGR workers, and in-depth interviews with ex-workers and policy-makers. While the policy response to the closure saw significant successes in terms of the great majority of workers successfully adjusting into re-employment, and with positive findings in terms of re-training and education, the paper finds significant challenges in terms of security of employment, income, job quality and representation at work years after closure. In particular, the paper posits that the general lack of attention to employment security at the macrolevel effectively undermined elements of a positive policy response over the longer run. This in turn suggests longer-term policy measures are required to address aspects of precariousness at work
Familial risk in testicular cancer as a clue to a heritable and environmental aetiology
We used the nation-wide Swedish Family-Cancer Database to examine the risk for testicular cancer in offspring through parental and sibling probands. Among 0-68-year-old offspring, 4082 patients had testicular cancer in years 1961-2000, among whom 68 (1.67%) had an affected father/brother. Standardized incidence ratios (SIRs) for familial risk were four-fold when a father and nine-fold when a brother had testicular cancer. Histology-specific risks (for the testicular cancer) were similar for sons of affected fathers, but were higher among brothers for teratoma and seminoma than for mixed histologies. Standardized incidence ratios for either histology depended on the age difference between the brothers: 10.81 when the age difference was less than 5 years compared to 6.69 for a larger age difference. Parental colorectal, pancreatic, lung and breast cancer and non-Hodgkin's lymphoma and Hodgkin's disease were associated with seminoma among sons. Seminoma risk was also increased when a sibling had melanoma. Teratoma was associated with parental lung cancer and melanoma. The high familial risk may be the product of shared childhood environment and heritable causes. Familial cases of fraternal pairs with an early-onset teratoma represent a challenge for gene identification
Characterizing a new class of variability in GRS 1915+105 with simultaneous INTEGRAL/RXTE observations
We report on the analysis of 100 ks INTEGRAL observations of the Galactic
microquasar GRS 1915+105. We focus on INTEGRAL Revolution number 48 when the
source was found to exhibit a new type of variability as preliminarily reported
in Hannikainen et al. (2003). The variability pattern, which we name , is
characterized by a pulsing behaviour, consisting of a main pulse and a shorter,
softer, and smaller amplitude precursor pulse, on a timescale of 5 minutes in
the JEM-X 3-35 keV lightcurve. We also present simultaneous RXTE data. From a
study of the individual RXTE/PCA pulse profiles we find that the rising phase
is shorter and harder than the declining phase, which is opposite to what has
been observed in other otherwise similar variability classes in this source.
The position in the colour-colour diagram throughout the revolution corresponds
to State A (Belloni et al. 2000) but not to any previously known variability
class. We separated the INTEGRAL data into two subsets covering the maxima and
minima of the pulses and fitted the resulting two broadband spectra with a
hybrid thermal--non-thermal Comptonization model. The fits show the source to
be in a soft state characterized by a strong disc component below ~6 keV and
Comptonization by both thermal and non-thermal electrons at higher energies.Comment: Accepted for publication in A&A. 11 pages, 10 figures, 4 in colour.
Original figures can be found at
http://www.astro.helsinki.fi/~diana/grs1915_rev48. Author affiliations
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A sex-chromosome mutation in Silene latifolia
Silene latifolia is dioecious, yet rare hermaphrodites have been found, and such natural mutants can provide valuable insight into genetic mechanisms. Here, we describe a hermaphrodite-inducing mutation that is almost certainly localized to the gynoecium-suppression region of the Y chromosome in S. latifolia. The mutant Y chromosome was passed through the megaspore, and the presence of two X chromosomes was not necessary for seed development in the parent. This result supports a lack of degeneration of the Y chromosome in S. latifolia, consistent with the relatively recent formation of the sex chromosomes in this species. When crossed to wild-type plants, hermaphrodites performed poorly as females, producing low seed numbers. When hermaphrodites were pollen donors, the sex ratio of offspring they produced through crosses was biased towards females. This suggests that hermaphroditic S. latifolia would fail to thrive and potentially explains the rarity of hermaphrodites in natural populations of S. latifolia. These results indicate that the Y chromosome in Silene latifolia remains very similar to the X, perhaps mostly differing in the primary sex determination regions
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