Hamara Healthy Living Centre - an evaluation

Hamara is a Healthy Living Centre which aims to improve health and well-being through providing a range of culturally appropriate activities and services. Hamara has a vision of 'bringing communities together' and since it was established in 2004, the Centre has provided a valuable community resource in South Leeds. Partnership work between Hamara and Leeds Met goes back to 2002. In 2007, the Centre for Health Promotion Research carried out an evaluation of Hamara in partnership with Hamara staff and Leeds Met Community Partnerships and Volunteering. This was followed by a highly successful community cohesion conference 'One Community' which was held at Hamara on 10th October 2008, and was supported through a Leeds Met public engagement grant. The event attracted over a hundred people from diverse communities and organisations across Leeds. A packed audience heard Hilary Benn, local MP and Patron of Hamara, talk about the importance of working in collaboration around community cohesion. Jane South, Centre for Health Promotion Research, presented the main evaluation results and set out the some challenges for the future. The proceedings concluded with the presentation of awards to a number of for local community champions who work to bring people together and make a real difference in the city of Leeds

Where do "red and dead" early-type void galaxies come from?

Void regions of the Universe offer a special environment for studying cosmology and galaxy formation, which may expose weaknesses in our understanding of these phenomena. Although galaxies in voids are observed to be predominately gas rich, star forming and blue, a sub-population of bright red void galaxies can also be found, whose star formation was shut down long ago. Are the same processes that quench star formation in denser regions of the Universe also at work in voids? We compare the luminosity function of void galaxies in the 2dF Galaxy Redshift Survey, to those from a galaxy formation model built on the Millennium Simulation. We show that a global star formation suppression mechanism in the form of low luminosity "radio mode" AGN heating is sufficient to reproduce the observed population of void early-types. Radio mode heating is environment independent other than its dependence on dark matter halo mass, where, above a critical mass threshold of approximately M_vir~10^12.5 M_sun, gas cooling onto the galaxy is suppressed and star formation subsequently fades. In the Millennium Simulation, the void halo mass function is shifted with respect to denser environments, but still maintains a high mass tail above this critical threshold. In such void halos, radio mode heating remains efficient and red galaxies are found; collectively these galaxies match the observed space density without any modification to the model. Consequently, galaxies living in vastly different large-scale environments but hosted by halos of similar mass are predicted to have similar properties, consistent with observations.Comment: 6 pages, 3 figures, accepted MNRA

Another note on Rossby wave energy flux

Author Posting. © American Meteorological Society, 2020. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 50(2),(2020): 531-534, doi:10.1175/JPO-D-19-0237.1.Longuet-Higgins in 1964 first pointed out that the Rossby wave energy flux as defined by the pressure work is not the same as that defined by the group velocity. The two definitions provide answers that differ by a nondivergent vector. Longuet-Higgins suggested that the problem arose from ambiguity in the definition of energy flux, which only impacts the energy equation through its divergence. Numerous authors have addressed this issue from various perspectives, and we offer one more approach that we feel is more succinct than previous ones, both mathematically and conceptually. We follow the work described by Cai and Huang in 2013 in concluding that there is no need to invoke the ambiguity offered by Longuet-Higgins. By working directly from the shallow-water equations (as opposed to the more involved quasigeostrophic treatment of Cai and Huang), we provide a concise derivation of the nondivergent pressure work and demonstrate that the two energy flux definitions are equivalent when only the divergent part of the pressure work is considered. The difference vector comes from the nondivergent part of the geostrophic pressure work, and the familiar westward component of the Rossby wave group velocity comes from the divergent part of the geostrophic pressure work. In a broadband wave field, the expression for energy flux in terms of a single group velocity is no longer meaningful, but the expression for energy flux in terms of the divergent pressure work is still valid.This work was supported by NASA Grants NNX13AE46G and NNX14AM71G, and National Science Foundation Grant OCE-1336752. We are indebted to Roger Samelson, Joe Pedlosky, and two anonymous reviewers for comments that significantly improved the presentation.2020-08-1

The wavenumber–frequency content of resonantly excited equatorial waves

Author Posting. © American Meteorological Society, 2012. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 42 (2012): 1834–1858, doi:10.1175/JPO-D-11-0234.1.The theoretical resonant excitation of equatorial inertia–gravity waves and mixed Rossby–gravity waves is examined. Contrary to occasionally published expectations, solutions show that winds that are broadband in both zonal wavenumber and frequency do not in general produce peaks in the wavenumber–frequency spectrum of sea surface height (SSH) at wavenumbers associated with vanishing zonal group velocity. Excitation of total wave energy in inertia–gravity modes by broadband zonal winds is virtually wavenumber independent when the meridional structure of the winds does not impose a bias toward negative or positive zonal wavenumbers. With increasing wavenumber magnitude |k|, inertia–gravity waves asymptote toward zonally propagating pure gravity waves, in which the magnitude of meridional velocity υ becomes progressively smaller relative to the magnitude of zonal velocity u and pressure p. When the total wave energy is independent of wavenumber, this effect produces a peak in |υ|2 near the wavenumber where group velocity vanishes, but a trough in |p|2 (or SSH variance). Another consequence of the shift toward pure gravity wave structure is that broadband meridional winds excite inertia–gravity modes progressively less efficiently as |k| increases and υ becomes less important to the wave structure. Broadband meridional winds produce a low-wavenumber peak in total wave energy leading to a subtle elevation of |p|2 at low wavenumbers, but this is due entirely to the decrease in the forcing efficiency of meridional winds with increasing |k|, rather than to the vanishing of the group velocity. Physical conditions that might alter the above conclusions are discussed.This research was funded by NASA Grant NNX10AO93G.2013-05-0

Experiments to Find or Exclude a Long-Lived, Light Gluino

Gluinos in the mass range ~1 1/2 - 3 1/2 GeV are absolutely excluded. Lighter gluinos are allowed, except for certain ranges of lifetime. Only small parts of the mass-lifetime parameter space are excluded for larger masses unless the lifetime is shorter than ~ 2 10^{-11} (m_{gluino}/ GeV) sec. Refined mass and lifetime estimates for R-hadrons are given, present direct and indirect experimental constraints are reviewed, and experiments to find or definitively exclude these possibilities are suggested.Comment: 27 pp, latex with 1 uufiled figure, RU-94-35. New version amplifies discussion of some points and corresponds to version for Phys. Rev.

Hadron Helicity Violation in Exclusive Processes: Quantitative Calculations in Leading Order QCD

We study a new mechanism for hadronic helicity flip in high energy hard exclusive reactions. The mechanism proceeds in the limit of perfect chiral symmetry, namely without any need to flip a quark helicity. The fundamental feature of the new mechanism is the breaking of rotational symmetry of the hard collision by a scattering plane in processes involving independent quark scattering. We show that in the impulse approximation there is no evidence for of the helicity violating process as the energy or momentum transfer $Q^2$ is increased over the region 1 GeV^2 < Q^2 < 100 GeV^2. In the asymptotic region Q^2> 1000 GeV^2, a saddle point approximation with doubly logarithmic accuracy yields suppression by a fraction of power of Q^2. ``Chirally--odd" exclusive wave functions which carry non--zero orbital angular momentum and yet are leading order in the high energy limit, play an important role.Comment: uuencoded LaTeX file (21 pages) and PostScript figure

Westward mountain-gap wind jets of the northern Red Sea as seen by QuikSCAT

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Remote Sensing of Environment 209 (2018): 677-699, doi:10.1016/j.rse.2018.02.075.We analyse ten years of QuikSCAT satellite surface winds to statistically characterize the spatio-temporal variability of the westward mountain-gap wind jets over the northern Red Sea. These wind jets bring relatively cold and dry air from the Arabian Desert, increasing heat loss and evaporation over the region similar to cold-air outbreaks from mid and subpolar latitudes. QuikSCAT captures the spatial structure of the wind jets and agrees well with in situ observations from a heavily instrumented mooring in the northern Red Sea. The local linear correlations between QuikSCAT and in situ winds are 0.96 (speed) and 0.85 (direction). QuikSCAT also reveals that cross-axis winds such as the mountain-gap wind jets are a major component of the regional wind variability. The cross-axis wind pattern appears as the second (or third) mode in the four vector Empirical Orthogonal Function analyses we performed, explaining between 6% to 11% of the wind variance. Westward wind jets are typical in winter, especially in December and January, but with strong interannual variability. Several jets can occur simultaneously and cover a large latitudinal range of the northern Red Sea, which we call large-scale westward events. QuikSCAT recorded 18 large-scale events over ten years, with duration between 3 to 8 days and strengths varying from 3–4 to 9–10 m/s. These events cause large changes in the wind stress curl pattern, imposing a remarkable sequence of positive and negative curl along the Red Sea main axis, which might be a wind forcing mechanism for the oceanic mesoscale circulation.This work was supported by NSF grant OCE-1435665 and NASA grant NNX14AM71G

Evaporative implications of dry-air outbreaks over the northern Red Sea.

Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Atmospheres, 124(9), (2019): CP3-4861, doi: 10.1029/2018JD028853.We investigate the impacts of westward wind events on the Red Sea evaporation using the 35‐year second Modern‐Era Retrospective analysis for Research and Applications reanalysis and a 2‐year‐long record of in situ observations from a heavily instrumented air‐sea interaction mooring. These events are common during boreal winter, and their effects are similar to cold‐air outbreaks that occur in midpolar and subpolar latitudes. They cause extreme heat loss from the sea, which is dominated by latent heat fluxes. Different from cold‐air outbreaks, the intensified heat loss is due to the low relative humidity as we show through latent heat flux decomposition. Rainfall is negligible during these events, and we refer to them as dry‐air outbreaks. We also investigate the general atmospheric circulation pattern that favors their occurrence, which is associated with an intensified Arabian High at the north‐central portion of the Arabian Peninsula—a feature that seems to be an extension of the Siberian High. The analyses reveal that the westward winds over the northern Red Sea and the winter Shamal winds in the Persian Gulf are very likely to be part of the same subsynoptic‐scale feature. The second Modern‐Era Retrospective analysis for Research and Applications reanalysis indicates that the occurrence of westward wind events over the northern Red Sea has grown from 1980 to 2015, especially the frequency of large‐scale events, the cause of which is to be investigated. We hypothesize that dry‐air outbreaks may induce surface water mass transformation in the surface Red Sea Eastern Boundary Current and could represent a significant process for the oceanic thermohaline‐driven overturning circulation.We thank the three anonymous reviewers and the associated editor who provided valuable comments that contributed to the improvement of the present paper. We wish to acknowledge the use of the Ferret program (NOAA/PMEL) and NCL (doi: 10.5065/D6WD3XH5) for analysis and graphics in this paper. We thanks Julie Hildebrandt for helping with the final manuscript version, Marcio Vianna for fruitful discussion about this work, and Stephen Swift for pointing out the long time series from Yenbo and Wejh at the National Climatic Data Center (NCDC/NOAA). We acknowledge the Global Modeling and Assimilation Office (GMAO) and the Goddard Earth Sciences Data and Information Services Center (GESDISC) for the dissemination of MERRA‐2 reanalysis and the NCDC/NOAA for making the Global Surface Summary of the Day freely and easily available on the internet. MERRA‐2 and QuikSCAT winds at 25 and 12.5 km data are available online (https://disc.gsfc.nasa.gov/datareleases/merra_2_data_release; www.remss.com/missions/qscat/; and https://podaac.jpl.nasa.gov, respectively). The in situ data from the WHOI/KAUST mooring is available at a WHOI repository (http://uop.whoi.edu/projects/kaust/form.php) and provided solely for academic and research purposes. The mooring data collected during the WHOI‐KAUST collaboration was made possible by award USA00001, USA00002, and KSA00011 to the WHOI by the KAUST in the Kingdom of Saudi Arabia. This work was supported by NSF grant OCE‐1435665 and NASA grant NNX14AM71G.2019-10-0