5,397 research outputs found
Wild Bee Conservation within Urban Gardens and Nurseries: Effects of Local and Landscape Management
Across urban environments, vegetated habitats provide refuge for biodiversity. Gardens (designed for food crop production) and nurseries (designed for ornamental plant production) are both urban agricultural habitats characterized by high plant species richness but may vary in their ability to support wild pollinators, particularly bees. In gardens, pollinators are valued for crop production. In nurseries, ornamental plants rarely require pollination; thus, the potential of nurseries to support pollinators has not been examined. We asked how these habitats vary in their ability to support wild bees, and what habitat features relate to this variability. In 19 gardens and 11 nurseries in California, USA, we compared how local habitat and landscape features affected wild bee species abundance and richness. To assess local features, we estimated floral richness and measured ground cover as proxies for food and nesting resources, respectively. To assess landscape features, we measured impervious land cover surrounding each site. Our analyses showed that differences in floral richness, local habitat size, and the amount of urban land cover impacted garden wild bee species richness. In nurseries, floral richness and the proportion of native plant species impacted wild bee abundance and richness. We suggest management guidelines for supporting wild pollinators in both habitats.DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli
Introduction to Library Trends 28 (1) Summer 1979: The Economics of Academic Libraries
published or submitted for publicatio
Jewish Community Study of New York: 2011 Special Report on Poverty
The sheer scale of needs associated with being poor or near poor dwarfs the resources of even the largest Jewish community in the United States. One is tempted to believe that the scale of need is so vast that the Jewish community should abandon this field to others.Yet since the earliest days of Jewish communal life in New York, the organized Jewish community has accepted its responsibilities to care for those in need. Even since the New Deal, when the federal government took on the primary role of providing a societal safety net, the Jewish community has been active in providing philanthropic support and services for poor and near-poor Jews.The numbers of poor and near-poor Jewish households, the enormous increase in the number of these households over the past 20 years, and the diverse groups affected by poverty create an imperative for an extraordinary response -- from government, the voluntary sector, the philanthropic sector, and all segments of society. These findings suggest that the organized Jewish community needs to take a hard look at current planning, advocacy, service delivery, and resource investment
An instability criterion for a finite amplitude localized disturbance in a shear flow of electrically conducting fluids
The stability of shear flows of electrically conducting fluids, with respect
to finite amplitude three-dimensional localized disturbances is considered. The
time evolution of the fluid impulse integral, characterizing such disturbances,
for the case of low magnetic Reynolds number is obtained by integrating
analytically the vorticity equation. Analysis of the resulted equation reveals
a new instability criterion.Comment: 10 pages in LaTex, no figures, accepted in Phys. Fluid
Studies of Bacterial Branching Growth using Reaction-Diffusion Models for Colonial Development
Various bacterial strains exhibit colonial branching patterns during growth
on poor substrates. These patterns reflect bacterial cooperative
self-organization and cybernetic processes of communication, regulation and
control employed during colonial development. One method of modeling is the
continuous, or coupled reaction-diffusion approach, in which continuous time
evolution equations describe the bacterial density and the concentration of the
relevant chemical fields. In the context of branching growth, this idea has
been pursued by a number of groups. We present an additional model which
includes a lubrication fluid excreted by the bacteria. We also add fields of
chemotactic agents to the other models. We then present a critique of this
whole enterprise with focus on the models' potential for revealing new
biological features.Comment: 1 latex file, 40 gif/jpeg files (compressed into tar-gzip). Physica
A, in pres
Modeling branching and chiral colonial patterning of lubricating bacteria
In nature, microorganisms must often cope with hostile environmental
conditions. To do so they have developed sophisticated cooperative behavior and
intricate communication capabilities, such as: direct cell-cell physical
interactions via extra-membrane polymers, collective production of
extracellular "wetting" fluid for movement on hard surfaces, long range
chemical signaling such as quorum sensing and chemotactic (bias of movement
according to gradient of chemical agent) signaling, collective activation and
deactivation of genes and even exchange of genetic material. Utilizing these
capabilities, the colonies develop complex spatio-temporal patterns in response
to adverse growth conditions. We present a wealth of branching and chiral
patterns formed during colonial development of lubricating bacteria (bacteria
which produce a wetting layer of fluid for their movement). Invoking ideas from
pattern formation in non-living systems and using ``generic'' modeling we are
able to reveal novel survival strategies which account for the salient features
of the evolved patterns. Using the models, we demonstrate how communication
leads to self-organization via cooperative behavior of the cells. In this
regard, pattern formation in microorganisms can be viewed as the result of the
exchange of information between the micro-level (the individual cells) and the
macro-level (the colony). We mainly review known results, but include a new
model of chiral growth, which enables us to study the effect of chemotactic
signaling on the chiral growth. We also introduce a measure for weak chirality
and use this measure to compare the results of model simulations with
experimental observations.Comment: 50 pages, 24 images in 44 GIF/JPEG files, Proceedings of IMA
workshop: Pattern Formation and Morphogenesis (1998
Social Links from Latent Topics in Microblogs
Language use is overlaid on a network of social con-nections, which exerts an influence on both the top-ics of discussion and the ways that these topics can be expressed (Halliday, 1978). In the past, efforts t
NASA Ames and Future of Space Exploration, Science, and Aeronautics
Pushing the frontiers of aeronautics and space exploration presents multiple challenges. NASA Ames Research Center is at the forefront of tackling these issues, conducting cutting edge research in the fields of air traffic management, entry systems, advanced information technology, intelligent human and robotic systems, astrobiology, aeronautics, space, earth and life sciences and small satellites. Knowledge gained from this research helps ensure the success of NASA's missions, leading us closer to a world that was only imagined as science fiction just decades ago
The Throat and The Voice: Rear Pages, Index, and Back Cover
Rear Pages, Index, and Back Coverhttps://jdc.jefferson.edu/throat_and_voice/1027/thumbnail.jp
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