1,596 research outputs found
Geophysical characteristics and crustal structure of greenstone terranes: Canadian Shield
Geophysical studies in the Canadian Shield have provided some insights into the tectonic setting of greenstone belts. Greenstone belts are not rooted in deep crustal structures. Geophysical techniques consistently indicate that greenstones are restricted to the uppermost 10 km or so of crust and are underlain by geophysically normal crust. Gravity models suggest that granitic elements are similarly restricted, although magnetic modelling suggests possible downward extension to the intermediate discontinuity around approx. 18 km. Seismic evidence demonstrates that steeply-dipping structure, which can be associated with the belts in the upper crust, is not present in the lower crust. Horizontal intermediate discontinuities mapped under adjacent greenstone and granitic components are not noticeably disrupted in the boundary zone. Geophysical evidence points to the presence of discontinuities between greenhouse-granite and adjacent metasedimentary erranes. Measured stratigraphic thicknesses of greenstone belts are often twice or more the vertical thicknesses determined from gravity modelling. Explantations advanced for the discrepancy include stratigraphy repeated by thrust faulting and/or listric normal faulting, mechanisms which are consistent with certain aspects of conceptual models of greenstone development. Where repetition is not a factor the gravity evidence points to removal of the root zones of greenstone belts. For one region, this has been attributed to magmatic stopping during resurgent caldera activity
Other Challenges in the Development of the Orbiter Environmental Control Hardware
Development of the Space Shuttle orbiter environmental control and life support system (ECLSS) included the identification and resolution of several interesting problems in several systems. Some of these problems occurred late in the program, including the flight phase. Problems and solutions related to the ammonia boiler system (ABS), smoke detector, water/hydrogen separator, and waste collector system (WCS) are addressed
Anxiety and depression symptoms in young people with perinatally acquired HIV and HIV affected young people in England
Adolescents with perinatal HIV (PHIV) may be at higher risk of anxiety and depression than HIV negative young people. We investigated the prevalence of symptoms of anxiety and depression in PHIV and HIV-affected (siblings of PHIV and/or had an HIV positive mother) young people in England. Symptoms were measured using the Hospital Anxiety and Depression Scale (HADS) scores. A cross-sectional analysis was conducted of data from 283 young people with PHIV aged 13-21 years and 96 HIV-affected young people aged 13-23 years in the Adolescents and Adults Living with Perinatal HIV (AALPHI) cohort. Linear regression investigated factors associated with higher (worse) anxiety and depression scores.115 (41%) and 29 (30%) PHIV and HIV-affected young people were male, median age was 16 [interquartile range 15,18] and 16 [14,18] years and 241 (85%) and 71 (74%) young people were black African, respectively. There were no differences in raw or z-scores of anxiety and depression, or self-esteem, between PHIV and HIV-affected participants (all p values >0.1). Across both PHIV and HIV-affected groups, factors associated with higher anxiety scores were having more carers in childhood, speaking a language other than English at home, lower self-esteem, and ever thinking life was not worth living and lower social functioning. Factors associated with higher depression scores were male sex, death of one or both parents, ever excluded from school, lower self-esteem and lower social functioning. This study found anxiety and depression scores were similar among PHIV and HIV-affected young people and similar to that of population norms. Other studies have found an association between poorer mental health and worse health outcomes in young people with PHIV, highlighting the need to identify young people at increased risk and provide timely support
Re-Focusing - Building a Future for Entrepreneurial Education & Learning
The field of entrepreneurship has struggled with fundamental
questions concerning the subject’s nature and purpose. To whom and to
what means are educational and training agendas ultimately directed?
Such questions have become of central importance to policy makers,
practitioners and academics alike. There are suggestions that university
business schools should engage more critically with the lived experiences
of practising entrepreneurs through alternative pedagogical approaches
and methods, seeking to account for and highlighting the social, political
and moral aspects of entrepreneurial practice. In the UK, where funding in
higher education has become increasingly dependent on student fees,
there are renewed pressures to educate students for entrepreneurial
practice as opposed to educating them about the nature and effects of
entrepreneurship. Government and EU policies are calling on business
schools to develop and enhance entrepreneurial growth and skill sets, to
make their education and training programmes more proactive in
providing innovative educational practices which help and facilitate life
experiences and experiential learning. This paper makes the case for
critical frameworks to be applied so that complex social processes
become a source of learning for educators and entrepreneurs and so that
innovative pedagogical approaches can be developed in terms both of
context (curriculum design) and process (delivery methods)
Quasiparticle States near the Surface and the Domain Wall in a p_x\pm i p_y-Wave Superconductor
The electronic states near a surface or a domain wall in the p-wave
superconductor are studied for the order parameter of the form p_x\pm i
p_y-wave, which is a unitary odd-parity state with broken time-reversal
symmetry. This state has been recently suggested as the superconducting state
of Sr_2 Ru O_4. The spatial variation of the order parameter and vector
potential is determined self-consistently within the quasi-classical
approximation. The local density of states at the surface is constant and does
not show any peak-like or gap-like structure within the superconducting energy
gap, in contrast to the case of the d-wave superconductors. The influence of an
external magnetic field is mainly observable in the energy range above the bulk
gap. On the other hand, there is a small energy gap in the local density of
states at the domain wall between domains of the two degenerate p_x+i p_y-wave
and p_x-i p_y-wave states.Comment: 26 pages, 9 figures, to be published in J. Phys. Soc. Jpn. Vol. 68
(1999) No. 3, erratum: to appear in J. Phys. Soc. Jpn. Vol. 68 (1999) No.
Constituting monetary conservatives via the 'savings habit': New Labour and the British housing market bubble
The ongoing world credit crunch might well kill off the most recent bubble dynamics in the British housing market by driving prices systematically downwards from their 2007 peak. Nonetheless, the experience of that bubble still warrants analytical attention. The Labour Government might not have been responsible for consciously creating it, but it has certainly grasped the opportunities the bubble has provided in an attempt to enforce a process of agential change at the heart of the British economy. The key issue in this respect is the way in which the Government has challenged the legitimacy of passive welfare receipts in favour of establishing a welfare system based on incorporating the individual into an active asset-holding society. The housing market has taken on new political significance as a means for individuals first to acquire assets and then to accumulate wealth on the back of asset ownership. The ensuing integration of the housing market into an increasingly reconfigured welfare system has permeated into the politics of everyday life. It has been consistent with individuals remaking their political subjectivities in line with preferences for the type of conservative monetary policies that typically keep house price bubbles inflated
Class I methanol masers in low-mass star formation regions
Four Class I maser sources were detected at 44, 84, and 95 GHz toward
chemically rich outflows in the regions of low-mass star formation NGC 1333I4A,
NGC 1333I2A, HH25, and L1157. One more maser was found at 36 GHz toward a
similar outflow, NGC 2023. Flux densities of the newly detected masers are no
more than 18 Jy, being much lower than those of strong masers in regions of
high-mass star formation. The brightness temperatures of the strongest peaks in
NGC 1333I4A, HH25, and L1157 at 44 GHz are higher than 2000 K, whereas that of
the peak in NGC 1333I2A is only 176 K. However, rotational diagram analysis
showed that the latter source is also a maser. The main properties of the newly
detected masers are similar to those of Class I methanol masers in regions of
massive star formation. The former masers are likely to be an extension of the
latter maser population toward low luminosities of both the masers and the
corresponding YSOs.Comment: 5 pages, 1 figure, Proc. IAU Symp. 287 "Cosmic Masers: from OH to
H0". LSR velocities of the HH25 masers, which are presented in Table 1, are
correcte
Ice chemistry in massive Young Stellar Objects: the role of metallicity
We present the comparison of the three most important ice constituents
(water, CO and CO2) in the envelopes of massive Young Stellar Objects (YSOs),
in environments of different metallicities: the Galaxy, the Large Magellanic
Cloud (LMC) and, for the first time, the Small Magellanic Cloud (SMC). We
present observations of water, CO and CO2 ice in 4 SMC and 3 LMC YSOs (obtained
with Spitzer-IRS and VLT/ISAAC). While water and CO2 ice are detected in all
Magellanic YSOs, CO ice is not detected in the SMC objects. Both CO and CO2 ice
abundances are enhanced in the LMC when compared to high-luminosity Galactic
YSOs. Based on the fact that both species appear to be enhanced in a consistent
way, this effect is unlikely to be the result of enhanced CO2 production in
hotter YSO envelopes as previously thought. Instead we propose that this
results from a reduced water column density in the envelopes of LMC YSOs, a
direct consequence of both the stronger UV radiation field and the reduced
dust-to-gas ratio at lower metallicity. In the SMC the environmental conditions
are harsher, and we observe a reduction in CO2 column density. Furthermore, the
low gas-phase CO density and higher dust temperature in YSO envelopes in the
SMC seem to inhibit CO freeze-out. The scenario we propose can be tested with
further observations.Comment: accepted by MNRAS Letters; 5 pages, 3 figures, 1 tabl
- …