6,247 research outputs found
A Roadmap for Integrating Human Rights Into the World Bank Group
Offers a framework for linking effective international development and poverty reduction with human rights, including empowering communities to use the World Bank Group's grievance mechanisms. Outlines accomplishments, shortfalls, and recommendations
SCUBA polarisation observations of the magnetic fields in the prestellar cores L1498 and L1517B
We have mapped linearly polarized dust emission from the prestellar cores
L1498 and L1517B with the James Clerk Maxwell Telescope (JCMT) using the
Submillimetre Common User Bolometer Array (SCUBA) and its polarimeter SCUBAPOL
at a wavelength of 850um. We use these measurements to determine the
plane-of-sky magnetic field orientation in the cores. In L1498 we see a
magnetic field across the peak of the core that lies at an offset of 19 degrees
to the short axis of the core. This is similar to the offsets seen in previous
observations of prestellar cores. To the southeast of the peak, in the
filamentary tail of the core, we see that the magnetic field has rotated to lie
almost parallel to the long axis of the filament. We hypothesise that the field
in the core may have decoupled from the field in the filament that connects the
core to the rest of the cloud. We use the Chandrasekhar-Fermi (CF) method to
measure the plane-of-sky field strength in the core of L1498 to be 10 +/- 7 uG.
In L1517B we see a more gradual turn in the field direction from the northern
part of the core to the south. This appears to follow a twist in the filament
in which the core is buried, with the field staying at a roughly constant 25
degree offset to the short axis of the filament, also consistent with previous
observations of prestellar cores. We again use the CF method and calculate the
magnetic field strength in L1517B also to be 30 +/- 10 uG. Both cores appear to
be roughly virialised. Comparison with our previous work on somewhat denser
cores shows that, for the denser cores, thermal and non-thermal (including
magnetic) support are approximately equal, while for the lower density cores
studied here, thermal support dominates.Comment: 6 pages, 2 figures; accepted for publication by MNRA
BIMA N2H+ 1-0 mapping observations of L183 -- fragmentation and spin-up in a collapsing, magnetized, rotating, pre-stellar core
We have used the Berkeley-Illinois-Maryland Array (BIMA) to make deep N2H+
1-0 maps of the pre-stellar core L183, in order to study the spatial and
kinematic substructure within the densest part of the core. Three spatially and
kinematically distinct clumps are detected, which we label L183-N1, L183-N2 and
L183-N3. L183-N2 is approximately coincident with the submillimetre dust peak
and lies at the systemic velocity of L183. Thus we conclude that L183-N2 is the
central dense core of L183. L183-N1 and 3 are newly-discovered fragments of
L183, which are marked by velocity gradients that are parallel to, but far
stronger than, the velocity gradient of L183 as a whole, as detected in
previous single-dish data. Furthermore, the ratio of the large-scale and
small-scale velocity gradients, and the ratio of their respective size-scales,
are consistent with the conservation of angular momentum for a rotating,
collapsing core undergoing spin-up. The inferred axis of rotation is parallel
to the magnetic field direction, which is offset from its long axis, as we have
seen in other pre-stellar cores. Therefore, we propose that we have detected a
fragmenting, collapsing, filamentary, pre-stellar core, rotating about its
B-field, which is spinning up as it collapses. It will presumably go on to form
a multiple protostellar system.Comment: 7 figures, 1 table, 21 pages, accepted for publication in Ap
Metal cluster hydrodesulfurization catalysts based on ternary molybdenum sulfides
Catalysts based on metal sulfide cluster compounds such as Chevrel phases (MxMo6S8) have been shown to possess high activity and selectivity for hydroprocessing reactions. Previous methods of preparing crystalline Chevrel phases have involved high temperature, solid-state synthetic routes which produce low surface area materials (0.1--1.0m2/gm). In our recent research, lower temperature syntheses via solution precursors have been explored as routes to these materials. The discovery of a new class of compounds, M2x/n n+(Mo6S8)Sx (n = 1--3) has resulted. These new reduced ternary molybdenum sulfides have been shown to have both high activity and selectivity in HDS reactions with thiophene, while also exhibiting initial surface areas near 200m2/gm. The stability and activity of these materials is dependent upon the pretreatment procedure. Surface area and porosity data have revealed a decrease in surface area and an increase in average pore size as the pretreatment temperature is increased. Temperature-programmed analysis studies were performed in conjunction with XPS to examine how the oxidation states change as a function of pretreatment temperature. The mechanism through which these new reduced ternary molybdenum sulfides convert to the crystalline Chevrel phase was also determined;The low temperature synthesis route of these new reduced molybdenum sulfides has allowed the synthesis of new cluster compounds, such as Pt(Mo6S8 )S. X-ray photoelectron spectroscopy, laser Raman spectroscopy, infrared spectroscopy and microprobe analysis indicate that this new material is structurally similar to other cluster compounds we have synthesized. Pretreatment of PtMoS in hydrogen at 950°C results in its conversion to the previously unknown crystalline Chevrel phase
Who is Eldest?
Assesses internal evidence in The Lord of the Rings to determine if Tom Bombadil is the eldest living creature in Middle-earth
Endothelial function response to different modes of acute and chronic exercise in both health and diseased populations
Endothelial microparticles (EMP) offer an insight into the state of the endothelium and are known to be elevated in diseases characterised by endothelial dysfunction (ED) (Horstman et al., 2004; Vince et al., 2009a). EMP have also been shown to increase after exercise/endothelial stress in healthy individuals (Sossdorf et al., 2011; Vince et al, 2009) but this area remains relatively novel.The purpose of the first experiment was to quantify the effects of an acute bout of strenuous exercise on the circulating levels of EMP and to assess if this effect is different after the ingestion of an extensively researched ergogenic aid (sodium bicarbonate, NaHCO3). Seven physically active and apparently healthy males volunteered to perform 10 x 15 second (s) cycle sprints after the ingestion of either 0.03 g.kg.BW⁻¹ NaHCO₃ or 0.045 g.kg.BW⁻¹ of a placebo (sodium chloride, NaCl) in capsules. The ingestion of NaHCO₃ induced a pre exercise alkalosis as evidenced by a significantly altered resting acid base status, but had no influence on levels of EMP in healthy males. As a result, the data was combined for the two experimental groups, and the exercise produced a significantly increased level of CD105+ MP (MP; microparticles) at 90 minutes (min) and 180 min when compared with resting levels (p = 0.010, p = 0.043 respectively). The observed peak value at 90 min was also significantly greater compared to immediately post exercise (p = 0.019). CD106+ MP also increased significantly to 90 min from immediately post exercise (p = 0.020) and this was still greater at 180 min compared to post exercise (p = 0.015). It was concluded that exercise of this nature was sufficient to elicit ED, although the endothelium shows signs of endothelial repair within a matter of hours (hr). Also, it appears that pre exercise alkalosis has no effect on the attenuation of EMP quantity.Additional work was completed to verify the novel finding that CD105+ MP and CD106+ MP appear markers of endothelial function (EF), and to further examine the quantification of EMP, this time in healthy females. There was also an additional blood draw in order to assess where the maximum level of endothelial stress was occurring post exercise. In the second experiment, 10 healthy females completed the identical repeated sprints protocol as the first experiment, this time without the ingestion of NaHCO₃. CD105+ MP were increased 90 min post exercise compared to immediately after exercise (p = 0.042). There was again a decline in both markers from 90 min to 180 min, although this was not significant. Furthermore, with the addition of a blood draw at 45 min post exercise, it was suggested that EMP levels appear to be rising between 45 min and 90 min post exercise, speculating this is the time point of greatest endothelial damage. Finally, shear stress was suggested as a key reason behind the increase in endothelial damage as a result of exercise, as indicated by significant changes in variables such as heart rate (HR) and systolic blood pressure (SBP).The third experiment employed a longer 90 min interval cycling protocol with the purpose of quantifying EF over a greater period of time, allowing investigation into whether the markers of EF were altered in the same way as the previous two experiments. It was also an aim to further assess the possible influence of shear stress factors on ED. Fourteen healthy males completed 90 min of high intensity aerobic exercise, and there were several changes in both CD105+ MP and CD106+ MP. CD105+ MP rose significantly from rest to an observed peak at 90 min (p = 0.019). Both of these markers indicated a significant restoration of the endothelium as indicated by a fall from peak values during recovery to 180 min post exercise (CD105+ MP, p = 0.009; CD106+ MP, p = 0.022). This experiment concluded that the endothelium is greatly affected by highly intense exercise over a prolonged period of time, but is recovered fully in a time period of 3 hr. The effects of shear stress again appear to be largely influential, but future work must now be conducted in order to build on the findings from this research and examine shear stress closely during exercise and its relationship with EMP quantification.It was the aim of the next experiment to investigate two separate methods of assessing EF (EMP and EndoPAT-2000), this time in a group of sedentary, but otherwise healthy individuals, in order to monitor the changes as a result of an acute bout of moderate intensity acute exercise. There were no significant differences found in EF as a result of exercise. This was indicated by no significant changes in CD105+ MP concentrations from pre to post exercise (p = 0.84) or pre to 60 min post exercise (p = 0.612). CD106+ MP concentrations showed a decrease from resting values (2513 CD106+ MP per μl platelet free plasma; PFP) to immediately post exercise (1368 CD106+ MP per μl PFP, p = 0.09), and again at 60 min post exercise (1293 CD106+ MP per μl PFP, p = 0.073) compared to resting values. Additionally, EndoPAT scores were unaffected by exercise, with values of reactive hyperaemia index (RHI) changing from rest (2.43) to post exercise (2.57), but this was not significant (p = 0.35). Correlations were carried out in order to determine and comparisons that may have existed between EMP and EndoPAT score using RHI. Although there was a slight trend for the higher numbers of CD105+ MP to correlate with the lower scores of RHI (r = 0.327) this was not significant (p = 0.171). CD106+ MP showed no correlations with RHI (r = -0.087, p = 0.717). This chapter suggested that exercise was not strenuous enough to see any significant changes in EF, and EMP continue to appear efficient markers of EF in a population of sedentary, healthy individuals.The final experimental chapter investigated the effects of a supervised 8 week moderate intensity exercise programme on women with polycystic ovary syndrome (PCOS) and control women free from any known disease. The aim was to assess if this type of exercise could improve EF in this population, and if there was a relationship with EMP (CD105+ MP and CD106+ MP) to other factors, such as body composition and cardiorespiratory fitness. EF was improved from baseline values to post exercise programme, with CD105+ MP concentrations reducing from 2113 CD105+ MP per μl PFP to 424 CD105+ MP per μl PFP (p = 0.025). Furthermore, control women showed no significant change from pre to post exercise programme in CD105+ MP (p = 0.25), or CD106+ MP (p = 0.99). Further analysis was performed to look for any associations with the changes in EMP compared to body composition changes as a result of exercise, but no significant correlations existed. This study concluded that supervised, moderate intensity exercise independent of substantial weight loss was enough to elicit an00 improvement in EF in women with PCOS compared to healthy control women. Additionally, EMP concentrations appear to be able to effectively map changes in EF across a long period of time in diseased states, adding to the notion that EMP may account for EF. Future work must now build on these findings from this research and examine this response in a larger cohort involving PCOS women with varied phenotypes and body composition
On the relativistic magnetic reconnection
Reconnection of the magnetic lines of force is considered in case the
magnetic energy exceeds the rest energy of the matter. It is shown that the
classical Sweet-Parker and Petschek models are generalized straightforwardly to
this case and the reconnection rate may be estimated by substituting the Alfven
velocity in the classical formulas by the speed of light. The outflow velocity
in the Sweet-Parker configuration is mildly relativistic. In the Petschek
configuration, the outflow velocity is ultrarelativistic whereas the angle
between the slow shocks is very small. Due to the strong compression, the
plasma outflow in the Petschek configuration may become strongly magnetized if
the reconnecting fields are not exactly antiparallel.Comment: Accepted by MNRA
SCUBA and Spitzer observations of the Taurus molecular cloud - pulling the bull's tail
We present continuum data from the Submillimetre Common-User Bolometer Array
(SCUBA) on the James Clerk Maxwell Telescope (JCMT), and the Mid-Infrared
Photometer for Spitzer (MIPS) on the Spitzer Space Telescope, at submillimetre
and infrared wavelengths respectively. We study the Taurus molecular cloud 1
(TMC1), and in particular the region of the Taurus Molecular Ring (TMR). In the
continuum data we see no real evidence for a ring, but rather we see one side
of it only, appearing as a filament. We name the filament `the bull's tail'.
The filament is seen in emission at 850, 450 and 160um, and in absorption at
70um. We compare the data with archive data from the Infra-Red Astronomical
Satellite (IRAS) at 12, 25, 60, 100um, in which the filament is also seen in
absorption. We find that the emission from the filament consists of two
components: a narrow, cold (~8K), central core; and a broader, slightly warmer
(~12K), shoulder of emission. We use a radiative transfer code to model the
filament's appearance, either in emission or absorption, simultaneously at each
of the different wavelengths. Our best fit model uses a Plummer-like density
profile and a homogeneous interstellar dust grain population. Unlike previous
work on a similar, but different filament in Taurus, we require no grain
coagulation to explain our data.Comment: 10 pages, 9 Figures, Accepted by MNRA
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