1,349 research outputs found
Neutral Hydrogen in the Ringed Barred Galaxies NGC 1433 and NGC 6300
We have made observations of the \ion{H}{1} in the southern ringed barred
spiral galaxies NGC~1433 and NGC~6300 with the Australia Telescope Compact
Array (ATCA), the main goal being to test the resonance theory for the origin
of these rings. NGC~1433 is the prototypical ringed barred spiral, and displays
distinct \ion{H}{1}~counterparts to its nuclear ring, inner ring, outer
pseudoring, and plume-like features. The and regions at
corotation, as well as the bar itself, are relatively devoid of neutral atomic
hydrogen. By associating the inner ring of NGC~1433 with the inner second
harmonic resonance, and its outer pseudoring with the outer Lindblad resonance,
we are able to infer a bar pattern speed for NGC~1433 of
~km~s~kpc. By way of contrast, NGC~6300 possesses a much
more extended \ion{H}{1}~disk than NGC~1433. There is a gas ring underlying the
inner pseudoring, but it is both broader and slightly larger in diameter than
the optical feature. By again linking this inner ring feature to the inner
second harmonic resonance, we derive a bar pattern speed for NGC~6300 of
~km~s~kpc, but in this case, neither the outer pseudoring
nor the nuclear ring predicted by the resonance-ring theory can be identified
in NGC~6300. Although it may be the case that the ring in NGC~6300 is not
related to a resonance with the bar at all, we postulate instead that NGC~6300
is merely a less well-developed example of a resonance-ring galaxy than is
NGC~1433.Comment: 21 pages, aas2pp4 LaTeX, no figures included. Accepted for April 1
1996 ApJ. Full paper (with figures) available from
http://www.phys.unsw.edu.au/~sdr/prep.htm
The value and significance of corporate community relations: an Italian SME perspective
Purpose – This paper investigates the link between community of place and small and medium-sized enterprises (SMEs) in Lombard industrial districts in Italy.
Design/methodology/approach – A brief literature review of international authors from the stakeholder approach and Corporate Community Relations field is presented. This paper refers to a survey of Lombard industrial districts conducted by ALTIS. The data was collected via a telephone survey from 834 firms.
Findings – The main finding is that managing Corporate Community Relations (CCR) is of major importance for company success. The results of the survey show that there are some tools and actions that Italian industrial district SMEs uses to interact with their particular communities of place to develop effective and coherent relationships with their stakeholder groups. Moreover, although the survey shows that though SMEs do implement different CCR activities, they are not able to communicate these effectively through systematic communication strategies. However, the narrow sample includes only a sample of some Lombard districts. Nonetheless, the findings indicate that effective CCR seems to confer competitive advantage based on stakeholder responses and rewards sought.
Research limitations/implications – The framework could assist in supporting CCR developments between industrial districts as various players would know how to improve CCR activities. One further suggestion is that University and Research Centres could have a role to play in creating and communicating codified knowledge concerning community relations in industrial districts, while other public players still have to develop specific tasks in improving infrastructures.
Originality/value – This study is in line with the main focus of CCR, which is in striving to meet stakeholder and societal needs. However, industrial district SMEs have to learn how to communicate their CCR activities from the examples set by large Italian companies. The paper links the notion of CCR with tools and actions to develop meaningful relationships with both community of place and interest. Moreover, considering the survey results, a new framework for local player roles is proposed
The Physical Characteristics of a CO2 Seeping Fault: the implications of fracture permeability for carbon capture and storage integrity
To ensure the effective long-term storage of CO2 in candidate geological storage sites, evaluation of potential leakage pathways to the surface should be undertaken. Here we use a series of natural CO2 seeps along a fault in South Africa to assess the controls on CO2 leakage to the surface. Geological mapping and detailed photogrammetry reveals extensive fracturing along the mapped fault trace. Measurements of gas flux and CO2 concentration across the fracture corridor give maximum soil gas measurements of 27% CO2 concentration and a flux of 191 g m−2 d−1. These measurements along with observations of gas bubbles in streams and travertine cones attest to CO2 migration to the surface. Permeability measurements on the host rock units show that the tillite should act as an impermeable seal to upward CO2 migration. The combined permeability and fracture mapping data indicate that fracture permeability creates the likely pathway for CO2 migration through the low permeability tillite to the surface. Heterogeneity in fracture connectivity and intensity at a range of scales will create local higher permeability pathways along the fracture corridor, although these may seal with time due to fluid-rock interaction. The results have implications for the assessment and choice of geological CO2 storage sites, particularly in the assessment of sub-seismic fracture networks
Early Cenozoic denudation of central west Britain in response to transient and permanent uplift above a mantle plume
Upwelling mantle plumes beneath continental crust are predicted to produce difficult to quantify, modest uplift and denudation. The contribution of permanent and transient components to the uplift is also difficult to distinguish. A pulse of denudation in Britain in the Early Paleogene has been linked, although with some controversy, with the arrival of the proto-Iceland mantle plume. In this contribution we show that combining apatite and zircon (U-Th-Sm)/He and apatite fission track analyses from central west Britain with numerical modeling clearly identifies a pulse of early Cenozoic denudation. The data indicate that rock uplift and denudation were centered on the northern East Irish Sea Basin and 1.0–2.4 km of rocks were removed during the latest Cretaceous-early Paleogene. Uplift and erosion appears to have started a few million years before the earliest magmatism in the region. The regional denudation pattern mirrors the distribution of low-density magmatic rocks that has been imaged in the deep crust. However, the injection of the underplating melt is not enough to account for the total denudation. An additional regional uplift of at least 300 m is required, which is consistent with a transient thermal effect from the hot mantle plume. The rapid exhumation event ceased by ~40 Ma and the data do not require significant Neogene exhumation
The HIPASS Catalogue - II. Completeness, Reliability, and Parameter Accuracy
The HI Parkes All Sky Survey (HIPASS) is a blind extragalactic HI 21-cm
emission line survey covering the whole southern sky from declination -90 to
+25. The HIPASS catalogue (HICAT), containing 4315 HI-selected galaxies from
the region south of declination +2, is presented in Meyer et al. (2004a, Paper
I). This paper describes in detail the completeness and reliability of HICAT,
which are calculated from the recovery rate of synthetic sources and follow-up
observations, respectively. HICAT is found to be 99 per cent complete at a peak
flux of 84 mJy and an integrated flux of 9.4 Jy km/s. The overall reliability
is 95 per cent, but rises to 99 per cent for sources with peak fluxes >58 mJy
or integrated flux > 8.2 Jy km/s. Expressions are derived for the uncertainties
on the most important HICAT parameters: peak flux, integrated flux, velocity
width, and recessional velocity. The errors on HICAT parameters are dominated
by the noise in the HIPASS data, rather than by the parametrization procedure.Comment: Accepted for publication in MNRAS. 12 pages, 11 figures. Paper with
higher resolution figures can be downloaded from http://hipass.aus-vo.or
Palaeogenomes of Eurasian straight-tusked elephants challenge the current view of elephant evolution
The straight-tusked elephants Palaeoloxodon spp. were widespread across Eurasia during the Pleistocene. Phylogenetic reconstructions using morphological traits have grouped them with Asian elephants (Elephas maximus), and many paleontologists place Palaeoloxodon within Elephas. Here, we report the recovery of full mitochondrial genomes from four and partial nuclear genomes from two P. antiquus fossils. These fossils were collected at two sites in Germany, Neumark-Nord and Weimar-Ehringsdorf, and likely date to interglacial periods ~120 and ~244 thousand years ago, respectively. Unexpectedly, nuclear and mitochondrial DNA analyses suggest that P. antiquus was a close relative of extant African forest elephants (Loxodonta cyclotis). Species previously referred to Palaeoloxodon are thus most parsimoniously explained as having diverged from the lineage of Loxodonta, indicating that Loxodonta has not been constrained to Africa. Our results demonstrate that the current picture of elephant evolution is in need of substantial revision
Search for Second-Generation Scalar Leptoquarks in Collisions at =1.96 TeV
Results on a search for pair production of second generation scalar
leptoquark in collisions at =1.96 TeV are reported. The
data analyzed were collected by the CDF detector during the 2002-2003 Tevatron
Run II and correspond to an integrated luminosity of 198 pb. Leptoquarks
(LQ) are sought through their decay into (charged) leptons and quarks, with
final state signatures represented by two muons and jets and one muon, large
transverse missing energy and jets. We observe no evidence for production
and derive 95% C.L. upper limits on the production cross sections as well
as lower limits on their mass as a function of , where is the
branching fraction for .Comment: 9 pages (3 author list) 5 figure
The theory of deformation fabrics : a theoretical examination of the effects of plastic deformation by dislocation glide on the development of preferred crystallographic orientation amongst the grains of a monomineralic mass of rock forming mineral, or of a metal, using quartz as a detailed example
Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt(s) = 1.96 TeV
We present a measurement of the top quark pair production cross section in
ppbar collisions at sqrt(s)=1.96 TeV using 318 pb^{-1} of data collected with
the Collider Detector at Fermilab. We select ttbar decays into the final states
e nu + jets and mu nu + jets, in which at least one b quark from the t-quark
decays is identified using a secondary vertex-finding algorithm. Assuming a top
quark mass of 178 GeV/c^2, we measure a cross section of 8.7 +-0.9 (stat)
+1.1-0.9 (syst) pb. We also report the first observation of ttbar with
significance greater than 5 sigma in the subsample in which both b quarks are
identified, corresponding to a cross section of 10.1 +1.6-1.4(stat)+2.0-1.3
(syst) pb.Comment: Accepted for publication in Physics Review Letters, 7 page
High NRF2 expression controls endoplasmic reticulum stress induced apoptosis in multiple myeloma
Multiple myeloma (MM) is an incurable disease characterized by clonal plasma cell proliferation. The stress response transcription factor Nuclear factor erythroid 2 [NF-E2]-related factor 2 (NRF2) is known to be activated in MM in response to proteasome inhibitors (PI). Here, we hypothesize that the transcription factor NRF2 whose physiological role is to protect cells from reactive oxygen species via the regulation of drug metabolism and antioxidant gene plays an important role in MM cells survival and proliferation. We report for the first time that NRF2 is constitutively activated in circa 50% of MM primary samples and all MM cell lines. Moreover, genetic inhibition of constitutively expressed NRF2 reduced MM cell viability. We confirm that PI induced further expression of NRF2 in MM cell lines and primary MM. Furthermore, genetic inhibition of NRF2 of PI treated MM cells increased ER-stress through the regulation of CCAAT-enhancer-binding protein homologous protein (CHOP). Finally, inhibition of NRF2 in combination with PI treatment significantly increased apoptosis in MM cells. Here we identify NRF2 as a key regulator of MM survival in treatment naive and PI treated cells
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