790 research outputs found
Enhancing seedling survival on former floodplain grazing land in the Capertee Valley, Australia
© 2017 Ecological Society of Australia and John Wiley & Sons Australia, Ltd Active revegetation is an essential component of biodiversity conservation for fragmented ecosystems and the species that depend on them. However, key knowledge gaps exist around the most cost-effective revegetation strategies to employ in different contexts. This article reports on a revegetation trial undertaken in the Capertee Valley of New South Wales, Australia, to assist the conservation of the critically endangered bird, the Regent Honeyeater (Anthochaera phrygia). Seven treatments were compared to assess their cost-effectiveness for enhancing plant survival at a floodplain site with a history of grazing on introduced pastures. While overall survival rates were low, treatments involving tree guards had higher survival rates and were more cost-effective than treatments without guards. Weed growth, animal activity and water stress all appeared to play a role in the low survival rates at this site, with enhanced weed control emerging as a priority for future trials at similar sites
p75 Neurotrophin receptor expression defines a population of BDNF-responsive neurogenic precursor cells
Although our understanding of adult neurogenesis has increased dramatically over the last decade, confusion still exists regarding both the identity of the stem cell responsible for neuron production and the mechanisms that regulate its activity. Here we show, using flow cytometry, that a small population of cells (0.3%) within the stem cell niche of the rat subventricular zone (SVZ) expresses the p75 neurotrophin receptor (p75(NTR)) and that these cells are responsible for neuron production in both newborn and adult animals. In the adult, the p75(NTR)-positive population contains all of the neurosphere-producing precursor cells, whereas in the newborn many of the precursor cells are p75(NTR) negative. However, at both ages, only the neurospheres derived from p75(NTR)-positive cells are neurogenic. We also show that neuron production from p75(NTR)-positive but not p75(NTR)-negative precursors is greatly enhanced after treatment with brain-derived neurotrophic factor (BDNF) or nerve growth factor. This effect appears to be mediated specifically by p75(NTR), because precursor cells from p75(NTR)-deficient mice show a 70% reduction in their neurogenic potential in vitro and fail to respond to BDNF treatment. Furthermore, adult p75(NTR)-deficient mice have significantly reduced numbers of PSA-NCAM ( polysialylated neural cell adhesion molecule)-positive SVZ neuroblasts in vivo and a lower olfactory bulb weight. Thus, p75(NTR) defines a discrete population of highly proliferative SVZ precursor cells that are able to respond to neurotrophin activation by increasing neuroblast generation, making this pathway the most likely mechanism for the increased neurogenesis that accompanies raised BDNF levels in a variety of disease and behavioral situations
Hungry for change: the Sydney Food Fairness Alliance
The Sydney Food Fairness Alliance is one of a growing number of nascent food movements in Australia to have emerged out of concern for the countryâs food future, as well as the deleterious effect the present food system is having on its citizensâ health and the continentâs fragile environment. The Allianceâs structure and activities clearly position it as a new social movement (NSM) engaged in collective action on a specific issue, in this instance, food security/justice, and operating outside the political sphere while aiming to influence and affect societal change. Food security as a human right lies at the heart of the Allianceâs philosophy, and equitable, sustainable food policies for New South Wales are a core focus of its advocacy work. The authors argue that the Alliance is a distinctive food movement in that it positions itself as an \u27umbrella\u27 organization representing a wide range of stakeholders in the food system. This chapter reflects on the values, achievements, issues of concern, strengths and weaknesses, and future of the Sydney Food Fairness Alliance.
This resource is Chapter 8 in \u27Food Security in Australia: Challenges and Prospects for the Future\u27 published by Springer in 2013
Laser diode ignition activities at Sandia National Laboratories
The topics are presented in viewgraph form and include the following: ignition subsystems, enhanced safety, optical ordnance power densities, optical ignition factors, low energy optical ordnance program, absorptance of 2-(5-cyanotetrazolato) pentaaminecobalt(III) perchlorate (CP) near 800 nm, power dependence of doped CP, system operational electrical requirements, dopant concentration effects for different CP particle sizes, ZR/KCLO4 optical ignition thresholds, and electrostatic discharge testing
Reviews
The following publications have been reviewed by the mentioned authors;An Italic Calligraphy Handbook by Carolyn Knudsen Adams, reviewed by John LancasterDesign and British Industry by Richard Stewart, reviewed by John H. CarswellDesign Graphics by David Fair and Marilyn Kenny, reviewed by D. R. JonesGCSE Craft, Design and Technology by Richard Kimbell, John Plater and Tristram Shepard, reviewed by D. R. JonesProblem Solving in Science and Technology by David Rowlands, reviewed by Peter C. MillrayTechnical Drawing, An Usborne Guide by Susan Peach, reviewed by Keith VickersTVEI and Secondary Education: a critical appraisal by Denis Gleeson, reviewed by Martin MersonWorking in Design by the Careers and Occupational Information Centre, reviewed by S. J. Lodg
A mass threshold in the number density of passive galaxies at z2
The process that quenched star formation in galaxies at intermediate and high
redshift is still the subject of considerable debate. One way to investigate
this puzzling issue is to study the number density of quiescent galaxies at
z~2, and its dependence on mass. Here we present the results of a new study
based on very deep Ks-band imaging (with the HAWK-I instrument on the VLT) of
two HST CANDELS fields (the UKIDSS Ultra-deep survey (UDS) field and
GOODS-South). The new HAWK-I data (taken as part of the HUGS VLT Large Program)
reach detection limits of Ks>26 (AB mag). We select a sample of
passively-evolving galaxies in the redshift range 1.4<z<2.5. Thanks to the
depth and large area coverage of our imaging, we have been able to extend the
selection of quiescent galaxies a magnitude fainter than previous analyses.
Through extensive simulations we demonstrate, for the first time, that the
observed turn-over in the number of quiescent galaxies at K>22 is real. This
has enabled us to establish unambiguously that the number counts of quiescent
galaxies at z~2 flatten and slightly decline at magnitudes fainter than
Ks~22(AB mag.). We show that this trend corresponds to a stellar mass threshold
below which the mechanism that halts the star
formation in high-redshift galaxies seems to be inefficient. Finally we compare
the observed pBzK number counts with those of quiescent galaxies extracted from
four different semi-analytic models. We find that none of the models provides a
statistically acceptable description of the number density of quiescent
galaxies at these redshifts. We conclude that the mass function of quiescent
galaxies as a function of redshift continues to present a key and demanding
challenge for proposed models of galaxy formation and evolution.Comment: Accepted for publication on Astronomy and Astrophysic
Degradation analysis in the estimation of photometric redshifts from non-representative training sets
We perform an analysis of photometric redshifts estimated by using a
non-representative training sets in magnitude space. We use the ANNz2 and GPz
algorithms to estimate the photometric redshift both in simulations as well as
in real data from the Sloan Digital Sky Survey (DR12). We show that for the
representative case, the results obtained by using both algorithms have the
same quality, either using magnitudes or colours as input. In order to reduce
the errors when estimating the redshifts with a non-representative training
set, we perform the training in colour space. We estimate the quality of our
results by using a mock catalogue which is split samples cuts in the -band
between . We obtain slightly better results with GPz on single
point z-phot estimates in the complete training set case, however the
photometric redshifts estimated with ANNz2 algorithm allows us to obtain mildly
better results in deeper -band cuts when estimating the full redshift
distribution of the sample in the incomplete training set case. By using a
cumulative distribution function and a Monte-Carlo process, we manage to define
a photometric estimator which fits well the spectroscopic distribution of
galaxies in the mock testing set, but with a larger scatter. To complete this
work, we perform an analysis of the impact on the detection of clusters via
density of galaxies in a field by using the photometric redshifts obtained with
a non-representative training set.Comment: 19 pages, 9 figures. Accepted for publication in MNRA
High-efficiency pharmacogenetic ablation of oligodendrocyte progenitor cells in the adult mouse CNS
Approaches to investigate adult oligodendrocyte progenitor cells (OPCs) by targeted cell ablation in the rodent CNS have limitations in the extent and duration of OPC depletion. We have developed a pharmacogenetic approach for conditional OPC ablation, eliminating >98% of OPCs throughout the brain. By combining recombinase-based transgenic and viral strategies for targeting OPCs and ventricular-subventricular zone (V-SVZ)-derived neural precursor cells (NPCs), we found that new PDGFRA-expressing cells born in the V-SVZ repopulated the OPC-deficient brain starting 12 days after OPC ablation. Our data reveal that OPC depletion induces V-SVZ-derived NPCs to generate vast numbers of PDGFRA+NG2+ cells with the capacity to proliferate and migrate extensively throughout the dorsal anterior forebrain. Further application of this approach to ablate OPCs will advance knowledge of the function of both OPCs and oligodendrogenic NPCs in health and disease
Wildlife hunting in complex human-environmental systems: How understanding natural resource use and human welfare can improve conservation in the Ankarafantsika National Park, Madagascar
Conservation officials work to manage complex and interacting human-environmental systems, where balancing needs between the two systems can become a source of tension. This study presents information on the use of natural resources by, and the health and welfare of, rural communities within and near Ankarafantsika National Park (ANP) in northwestern Madagascar. We focus on behaviors that are difficult for natural resource managers to measure themselves, including the hunting of threatened and protected wildlife and on sensitive information about humanwealth, health, and food security. We surveyed 41 9 households and measured the health of 1 860 individuals in 1 8 communities adjacent to or within the boundaries of ANP. We found a very high prevalence of child malnutrition, illness, and food insecurity and a heavy reliance on natural products to meet subsistence needs. More than 90% of the population reported that they hunted wildlife and harvested wild vegetables at least one day during the prior week as a direct means to cope with their food insecurity. Further, we found a high reliance on the forest for both healthcare and the building of adequate shelter. Efforts to improve overall food security would likely improve both human welfare and the long-term conservation of the threatened wildlife and habitat of Ankarafantsika. These data can help both conservation and community livelihood programs to find integrated solutions to the shared challenges of improving the well-being of human populations and the protection of Madagascarâs unique, endemic, and highly threatened biodiversity.
Les gestionnaires oeuvrant pour la protection de la nature sont gĂ©nĂ©ralement confrontĂ©s Ă des systĂšmes socio-Ă©cologiques complexes et interactifs dans lesquels la recherche de lâĂ©quilibre entre les besoins de ces deux systĂšmes peut sâavĂ©rer ĂȘtre une source de tension. Cette Ă©tude prĂ©sente des informations sur l'utilisation des ressources naturelles par les communautĂ©s rurales riveraines du parc national d'Ankarafantsika (PNA) dans le nord-ouest de Madagascar, ainsi que sur la santĂ© et le bien-ĂȘtre de ces communautĂ©s. LâĂ©tude sâest en particulier orientĂ©e sur les comportementsdifficiles Ă mesurer pour les gestionnaires de ressources naturelles, Ă savoir la chasse d'animaux sauvages menacĂ©s et protĂ©gĂ©s et les informations portant sur lâopulence, la santĂ© et la sĂ©curitĂ© alimentaire des gens. Une enquĂȘte a Ă©tĂ© rĂ©alisĂ©e auprĂšs de 41 9 mĂ©nages et lâĂ©tat de santĂ© de 1 860 personnes a Ă©tĂ© mesurĂ© dans 1 8 communautĂ©s vivant Ă la pĂ©riphĂ©rie ou Ă lâintĂ©rieur des limites du PNA. Une trĂšs forte prĂ©valence de la malnutrition infantile a Ă©tĂ© observĂ©e ainsi que diverses pathologies, une insĂ©curitĂ© alimentaire et une dĂ©pendance importante Ă l'Ă©gard des produits naturels pour rĂ©pondre aux besoins de subsistance. Plus de 90% de la population a dĂ©clarĂ© qu'elle avait chassĂ© des animaux et rĂ©coltĂ© des plantes sauvages au moins un jour au cours de la semaine prĂ©cĂ©dente, Ă titre de moyen direct pour faire face Ă l' insĂ©curitĂ© alimentaire. Une forte dĂ©pendance Ă l'Ă©gard des forĂȘts a Ă©galement Ă©tĂ© notĂ©e pour les produits destinĂ©s Ă la santĂ© et la construction de maisons. Les efforts visant Ă amĂ©liorer la sĂ©curitĂ© alimentaire dans son ensemble pourraient vraisemblablement amĂ©liorer le bien-ĂȘtre humain aussi bien que la conservationĂ long terme de la faune et des habitats menacĂ©s de l'Ankarafantsika. Ces donnĂ©es peuvent aider les programmes de conservation et de subsistance de la communautĂ© Ă trouver des solutions intĂ©grĂ©es aux problĂšmes communs de lâamĂ©lioration du bien-ĂȘtre des populations humaines et de la protection de la biodiversitĂ© unique, endĂ©mique et hautement menacĂ©e de Madagascar
The ALHAMBRA survey: Evolution of galaxy clustering since zâŒ1
We study the clustering of galaxies as function of luminosity and redshift in the range 0.35< z < 1.25 using data from the Advanced Large Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey. The ALHAMBRA data used in this work cover 2.38 deg2 in seven independent fields, after applying a detailed angular selection mask, with accurate photometric redshifts,ÏzâČ 0.014(1 + z), down to IAB < 24. Given the depth of the survey, we select samples in B-band luminosity down to Lth â 0.16L* at z=0.9. We measure the real-space clustering using the projected correlation function, accounting for photometric redshifts uncertainties. We infer the galaxy bias, and study its evolution with luminosity. We study the effect of sample variance, and confirm earlier results that the Cosmic Evolution Survey (COSMOS) and European Large Area ISO Survey North 1 (ELAIS-N1) fields are dominated by the presence of large structures. For the intermediate and bright samples, Lmed âł 0.6L*, we obtain a strong dependence of bias on luminosity, in agreement with previous results at similar redshift. We are able to extend this study to fainter luminosities, where we obtain an almost flat relation, similar to that observed at low redshift. Regarding the evolution of bias with redshift, our results suggest that the different galaxy populations studied reside in haloes covering a range in mass between log10[Mh( h-1M{bull's eye})] âł 11.5 for samples with Lmed = 0.3L* and log10[Mh( h-1Mâ)] âł 13.0 for samples with Lmed = 2L*, with typical occupation numbers in the range of 1-3 galaxies per halo.Junta de AndalucĂa P08-TIC-3531Ministerio de Ciencia e InnovaciĂłn AYA2010-22111- C03-01 CSD2007-0006
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