Effects of horizontal vibration on hopper flows of granular materials

The current experiments investigate the discharge of glass spheres in a planar wedge-shaped hopper (45 degree sidewalls) that is vibrated hoizontally. When the hopper is discharged without vibration, the discharge occurs as a funnel flow, with the material exiting the central region of the hopper and stagnant material along the sides. With horizontal vibration, the discharge rate increases with the velocity of vibration as compared with the discharge rate without vibration. For a certain range of acceleration parameters (20-30 Hz and accelerations greater than about 1 g), the discharge of the material occurs in an inverted-funnel pattern, with the material along the sides exiting first, followed by the material in the core; the free surface shows a peak at the center of the hopper with the free surface particles avalanching from the center toward the sides. During the deceleration phase of a vibration cycle, particles all along the trailing or low-pressure wall separate from the surface and fall under gravity for a short period before reconnecting the hopper. For lower frequencies (5 and 10 Hz), the free surface remains horizontal and the material appears to discharge uniformly from the hopper

Effects of Horizontal Vibration on Hopper Flows of Granular Material

This study experimentally examines the flow of glass spheres in a wedge-shaped hopper that is vibrated hoizontally. When the hopper is discharged without vibration, discharge occurs as a funnel flow, with the material exiting the central region of the hopper and stagnant material along the sides. With vibration, the discharge of the material occurs in reverse, with the material along the sides exiting first, followed by the material in the central region. These patterns are observed with flow visualization and high-speed photography. The study also includes measurements of the discharge rate, which increases with the amplitude of the velocity of vibration

Income Security for Workers: A Stressed Support System in Need of Innovation

The current mix of public and private programs to support workers after they experience disability onset provides benefits to millions of workers and former workers. Yet, despite the large and growing costs of these programs, the inflation-adjusted household incomes of workers with disabilities have been falling for over two decades, both absolutely and, especially, relative to the incomes of those without disabilities. The aging of the baby boom generation is likely to make matters worse, and the government’s fiscal circumstance will make it increasingly difficult to sustain existing public programs. Current public policy initiatives might eventually improve the disability support system, but they are not likely to ward off the adverse consequences of the pending crisis. Policy changes that leverage existing private sector practices and capabilities might achieve greater success, but have received little attention and are far from proven

Counting Working-Age People with Disabilities: What Current Data Tell Us and Options for Improvement

This book offers a systematic review of what current statistics and data on working-age people with disabilities can and cannot tell us, and how the quality of the data can be improved to better inform policymakers, advocates, analysts, service providers, administrators, and others interested in this at-risk population.https://research.upjohn.org/up_press/1162/thumbnail.jp

Onshore Wind Speed Modulates Microbial Aerosols along an Urban Waterfront

Wind blowing over aquatic and terrestrial surfaces produces aerosols, which include microbial aerosols. We studied the effect of onshore wind speeds on aerosol concentrations as well as total and culturable microbial aerosols (bacterial and viral) at an urban waterfront (New York, NY, USA). We used two distinct methods to characterize microbial aerosol responses to wind speed: A culture-based exposure-plate method measuring viable bacterial deposition near-shore (CFU accumulation rate); and a culture-independent aerosol sampler-based method measuring total bacterial and viral aerosols (cells m−3 air). While ambient coarse (\u3e2 µm) and fine (0.3–2 µm) aerosol particle number concentrations (regulated indicators of air quality) decreased with increasing onshore wind speeds, total and depositing culturable bacterial aerosols and total viral aerosols increased. Taxonomic identification of the 16S rDNA of bacterial aerosol isolates suggested both terrestrial and aquatic sources. Wind appears to increase microbial aerosol number concentrations in the near-shore environment by onshore transport at low wind speeds (s−1 ), and increased local production and transport of new microbial aerosols from adjacent water surfaces at higher wind speeds (\u3e4 m s−1 ). This study demonstrates a wind-modulated microbial connection between water and air in the coastal urban environment, with implications for public health management and urban microbial ecology

Time Constants of Heating and Cooling in the Eastern Water Dragon. Physignathus Lesueurii and Some Generalizations About Heating and Cooling in Reptiles

In keeping with other reptiles, core temperature of the lizard Physignathus lesueurii responds more rapidly to a step function increase in temperature than to a corresponding decrease. 2. Observations on twelve species (five families) of non-Chelonian reptiles heating and cooling in air and water show that strongly predictable relationships exist between thermal time constants and body size. Chelonia show a different pattern. 3. These observations are compared with the predictions of a simple model which, although not sufficiently complex to simulate physiological changes, provides insight into the relative importance of the physical and biological factors which underlie the observed relationships

“New” cyanobacterial blooms are not new: two centuries of lake production are related to ice cover and land use

Recent cyanobacterial blooms in otherwise unproductive lakes may be warning signs of impending eutrophication in lakes important for recreation and drinking water, but little is known of their historical precedence or mechanisms of regulation. Here, we examined long-term sedimentary records of both general and taxon-specific trophic proxies from seven lakes of varying productivity in the northeastern United States to investigate their relationship to historical in-lake, watershed, and climatic drivers of trophic status. Analysis of fossil pigments (carotenoids and chlorophylls) revealed variable patterns of past primary production across lakes over two centuries despite broadly similar changes in regional climate and land use. Sediment abundance of the cyanobacterium Gloeotrichia, a large, toxic, nitrogen-fixing taxon common in recent blooms in this region, revealed that this was not a new taxon in the phytoplankton communities but rather had been present for centuries. Histories of Gloeotrichia abundance differed strikingly across lakes and were not consistently associated with most other sediment proxies of trophic status. Changes in ice cover most often coincided with changes in fossil pigments, and changes in watershed land use were often related to changes in Gloeotrichia abundance, although no single climatic or land-use factor was associated with proxy changes across all seven lakes. The degree to which changes in lake sediment records co-occurred with changes in the timing of ice-out or agricultural land use was negatively correlated with the ratio of watershed area to lake area. Thus, both climate and land management appeared to play key roles in regulation of primary production in these lakes, although the manner in which these factors influenced lakes was mediated by catchment morphometry. Improved understanding of the past interactions between climate change, land use, landscape setting, and water quality underscores the complexity of mechanisms regulating lake and cyanobacterial production and highlights the necessity of considering these interactions—rather than searching for a singular mechanism—when evaluating the causes of ongoing changes in low-nutrient lakes

Macrosystems ecology: Understanding ecological patterns and processes at continental scales

Macrosystems ecology is the study of diverse ecological phenomena at the scale of regions to continents and their interactions with phenomena at other scales. This emerging subdiscipline addresses ecological questions and environmental problems at these broad scales. Here, we describe this new field, show how it relates to modern ecological study, and highlight opportunities that stem from taking a macrosystems perspective. We present a hierarchical framework for investigating macrosystems at any level of ecological organization and in relation to broader and finer scales. Building on well-established theory and concepts from other subdisciplines of ecology, we identify feedbacks, linkages among distant regions, and interactions that cross scales of space and time as the most likely sources of unexpected and novel behaviors in macrosystems. We present three examples that highlight the importance of this multiscaled systems perspective for understanding the ecology of regions to continents