The Gas Properties of the W3 GMC: A HARP study

We present 12CO, 13CO and C18O J=3-2 maps of the W3 GMC made at the James Clerk Maxwell Telescope. We combine these observations with Five Colleges Radio Astronomy Observatory CO J=1-0 data to produce the first map of molecular-gas temperatures across a GMC and the most accurate determination of the mass distribution in W3 yet obtained. We measure excitation temperatures in the part of the cloud dominated by triggered star formation (the High Density Layer, HDL) of 15-30 K, while in the rest of the cloud, which is relatively unaffected by triggering (Low Density Layer, LDL), the excitation temperature is generally less than 12 K. We identify a temperature gradient in the HDL which we associate with an age sequence in the embedded massive star-forming regions. We measure the mass of the cloud to be 4.4+/-0.4 x 10^5 solar masses, in agreement with previous estimates. Existing sub-mm continuum data are used to derive the fraction of gas mass in dense clumps as a function of position in the cloud. This fraction, which we interpret as a Clump Formation Efficiency (CFE), is significantly enhanced across the HDL, probably due to the triggering. Finally, we measure the 3D rms Mach Number as a function of position and find a correlation between the Mach number and the CFE within the HDL only. This correlation is interpreted as due to feedback from the newly-formed stars and a change in its slope between the three main star-forming regions is construed as another evolutionary effect. We conclude that triggering has affected the star-formation process in the W3 GMC primarily by creating additional dense structures that can collapse into stars. Any traces of changes in CFE due to additional turbulence have since been overruled by the feedback effects of the star-forming process itself.Comment: 14 pages, 11 figures, 1 table, accepted for publication in MNRA

Molecular gas in Arp 94: Implications for intergalactic star formation

We present $^{12}$CO(1-0) observations of the interacting galaxy system Arp 94, which contains the Seyfert galaxies NGC 3227 and NGC 3226 as well as the star-forming candidate dwarf galaxy J1023+1952. We mapped the CO distribution in J1023+1952 with the IRAM 30m telescope and found molecular gas across the entire extent of the neutral hydrogen cloud -- an area of about 9 by 6 kpc. The region where star formation (SF) takes place is restricted to a much smaller ($\sim$ 1.5 by 3 kpc) region in the south where the narrow line width of the CO shows that the molecular gas is dynamically cold. Neither the molecular nor the total gas surface density in the SF region are significantly higher than in the rest of the object suggesting that an external trigger is causing the SF. The fact that CO is abundant and apparently a good tracer for the molecular gas in J1023+1952 indicates that its metallicity is relatively high and argues for a tidal origin of this object.Comment: 5 pages, to appear in the proceedings of "The fate of gas in galaxies", held in Dwingeloo, July 200

Sign of the crossed conductances at a FSF double interface

Crossed conductance in hybrid Ferromagnet / Superconductor / Ferromagnet (FSF) structures results from the competition between normal transmission and Andreev reflection channels. Crossed Andreev reflection (CAR) and elastic cotunneling (EC) between the ferromagnets are dressed by local Andreev reflections, which play an important role for transparent enough interfaces and intermediate spin polarizations. This modifies the simple result previously obtained at lowest order, and can explain the sign of the crossed resistances in a recent experiment [D. Beckmann {\sl et al.}, cond-mat/0404360]. This holds both in the multiterminal hybrid structure model (where phase averaging over the Fermi oscillations is introduced ``by hand'' within the approximation of a single non local process) and for infinite planar interfaces (where phase averaging naturally results in the microscopic solution with multiple non local processes).Comment: 9 pages, 7 figure

Associations of long chain polyunsaturated fatty acids with bone mineral density and bone turnover in postmenopausal women

PURPOSE: The immunomodulatory properties of n-3 long chain polyunsaturated fatty acids (LCPUFA) are reported to reduce bone loss through alteration of bone remodelling and n-3 LCPUFA, therefore, may benefit bone health in post-menopausal women, a vulnerable group at high risk of osteoporosis. METHODS: Measures of bone mineral density (BMD) were determined using dual energy X-ray absorptiometry (DEXA) in 300 post-menopausal women. The bone turnover markers osteocalcin (OC), C-terminal telopeptides of type 1 collagen (CTX) and total alkaline phosphatase were quantified in serum along with urinary creatinine corrected deoxypyridinoline (DPD/Cr) and CTX/Cr and the CTX:OC ratio calculated. Total serum n-6 PUFA (LA + AA) and n − 3 LCPUFA (ALA + EPA + DPA + DHA) were measured and the n − 6:n − 3 ratio was calculated. RESULTS: Mean (SD) age and body mass index (BMI) were 61 (6.4) years and 27.4 (4.8) kg/m(2), respectively with participants being 12.6 (7.6) years post-menopause. Multiple regression analysis identified no association between n-3 LCPUFA and any of the measures of T-score or BMD albeit a significant positive association between total n − 3 LCPUFA and femur BMD (β = 0.287; p = 0.043) was observed within those women with a low n − 6:n − 3 ratio. There was a significant inverse association between ALA and urinary DPD/Cr (β = − 0.141; p = 0.016). CONCLUSION: A favourable low n − 6:n − 3 ratio was associated with higher femur BMD and a higher n − 3 LCPUFA (ALA) was associated with lower bone resorption. These results support a beneficial role for n − 3 LCPUFA in reducing postmenopausal bone resorption and favourably influencing BMD. TRIAL NUMBER & DATE OF REGISTRATION: ISRCTN63118444, 2nd October 2009, “Retrospectively registered”

Phenotypic variation in heteroblastic woody species does not contribute to shade survival

Heteroblastic species change their leaf morphology due to changes in light environment. However, growth and biomass allocation pattern do not contribute to their better survival relative to homoblastic congeners in low light. Thus, shade does not select for leaf heteroblasty

BEAR PGR Conference 2023 - Conference proceedings

BEAR Conference proceedings are the collection of papers and posters that were presented at the BEAR PGR conference. Conferences provide opportunities for people to present their research, and get input from other researchers and colleagues in their field

Institutions and governance of communal rangelands in South Africa

The creation of local institutions with a mandate over land access and control is seen as a prerequisite for successful decentralisation of land tenure and effective local resource management in sub-Saharan Africa. However, with land tenure reform in South Africa currently at a state of legislative impasse, real uncertainty now exists over land rights and governance of rangeland in many communal areas. This paper draws on case study material from Eastern Cape province to illustrate how this ongoing uncertainty has resulted in the operation of a range of traditional authority and civil society institutions in different communal areas with varying degrees of legitimate authority over land administration and highly variable performance in managing rangeland resources. Collective management of rangeland resources seems most difficult in environments where land rights are contested because of the coexistence of traditional leaders and civil society institutions. On this basis an approach to tenure reform is advocated, which vests all powers over local land administration in democratically elected and accountable civil society institutions. Some successful examples of this already exist and might serve to guide policy formation, which must be flexible enough to accommodate collective management approaches that emphasise cooperation both within and between communities.Keywords: common property, land tenure, natural resource management, traditional leadersAfrican Journal of Range & Forage Science 2013, 30(1&2): 77–8