Fog precipitation in the Sierra de las Minas Biosphere Reserve,Guatemala

Fog precipitation occurs when fog droplets are filtered by the forest canopy and coalesce on the vegetative surfaces to form larger water droplets that drip to the forest floor. This study examines the quantity of throughfall compared with incident precipitation produced by the canopy of a lower montane rain forest (2100 m) and an upper montane cloud forest (2550 m) in the Sierra de las Minas Biosphere Reserve, Guatemala. Fog precipitation was measured with throughfall and precipitation gauges from 23 July 1995 to 7 June 1996. Fog precipitation occurred during sampling periods when throughfall exceeded incident precipitation. Fog precipitation contributed <1% of total water inputs in the cloud forest at 2100 m during the 44‐week period, whereas fog precipitation contributed 7·4% at 2550 m during the same period. The depth equivalent of fog precipitation was greater at 2550 m (203·4 mm) than at 2100 m (23·4 mm). The calculation of fog precipitation in this study is underestimated. The degree of underestimation may be evident in the difference in apparent rainfall interception between 2100 m (35%) and 2550 m (4%). Because the apparent interception rate at 2550 m is significantly lower than 2100 m, the canopy probably is saturated for longer periods as a result of cloud water contributions. Data show a seasonal pattern of fog precipitation most evident at the 2550 m site. Fog precipitation represented a larger proportion of total water inputs during the dry season (November to May). Because cloud forests generate greater than 1 mm day^?1 of fog precipitation in higher elevations of the Sierra de las Minas, the conservation of the cloud forest may be important to meet the water demands of a growing population in the surrounding arid lowlands. Copyright © 2003 John Wiley & Sons, Ltd.     

Collisionless Saturnian rings

We show that particles orbiting a central body ($\text{i.e.}$, Saturn's rings) can be assembled into one or more dense ($\text{i.e.}$, opaque) independent rings without interparticle collisions taking place despite the inevitable particle oscillations about the ring plane. The resultant apparent bulk motion is a slow “rolling” motion of the ring, as it orbits, the individual rings describing a “helical” motion. Such rings would only evolve due to external perturbations or (slow) internal gravitational perturbations, since the particles need never collide. This picture opens up the possibility of having hollow rings, for example. Moreover, it is possible that an initially uniform disk of randomly moving particles may spontaneously separate into a series of such rings. The consequence would be a striated disk having virtually zero internal viscosity.     

A long-duration balloon payload for hard X-ray and gamma-ray observations of the sun

We describe a balloon payload designed to study the processes of energy release, particle acceleration, and heating of the active corona, in hard X-ray microflares and normal flares. An array of liquid nitrogen-cooled germanium detectors together with large area phoswich scintillation detectors provide the highest sensitivity (500 cm²) and energy resolution (0.7 keV) ever achieved for solar hard X-ray (15–600 keV) measurements. These detectors were flown in February 1987 from Australia on a long duration RAdiation COntrolled balloON (RACOON) flight (LDBF) which provided 12 days of observations before cutdown in Brazil. The payload includes solar cells for power, pointing and navigation sensors, a microprocessor controlled data system with VCR tape storage, and transmitters for GOES and ARGOS spacecraft. This successful flight illustrates the potential of LDBF's for solar flare studies.Also Physics Department.Presently at Space Sciences Laboratory, University of California, Berkeley CA 94720.     

Centrifugal instability of the jovian magnetosphere and its interaction with the solar wind

The outer regions (r > 2.3 R_j; R_j = radius of Jupiter) of the magnetosphere of Jupiter will systematically accumulate plasma. If sufficient plasma accumulates, the field lines must open to allow the plasma to escape. Available energy sources appear able to supply plasma at a high enough rate to keep the field lines constantly open beyond about 60 R_J. We suggest that the solar wind interaction with Jupiter may be essentially different from that with the Earth, with the Jovian magnetosphere opening up to form a planetary wind.     

Geospatial cryptography: enabling researchers to access private,spatially referenced,human subjects data for cancer control and prevention

Journal of Geographical Systems - As the volume, accuracy and precision of digital geographic information have increased, concerns regarding individual privacy and confidentiality have come to the...     

A multi-level perspective on small-area health and mortality: a case study of England and Wales

"This paper considers morbidity and mortality variations at the small-area level in England and Wales and their relation to socio-economic factors. Separate affluence and deprivation effects on illness and mortality are identified from a single-level analysis, both exceeding the influence of social class, urbanity or ethnicity. A multi-level perspective is then adopted to explore ecological associations operating both at micro-area and higher level spatial scales. Contextual effects (higher level variability in the impacts of ward level variables) are identified in the effects of small area deprivation on mortality and illness, as well as cross-level interactions; thus the impact of small area social structure on health is partly defined by the wider regional and district setting."     

Red Waters of <Emphasis Type="Italic">Myrionecta rubra</Emphasis> are Biogeochemical Hotspots for the Columbia River Estuary with Impacts on Primary/Secondary Productions and Nutrient Cycles

The localized impact of blooms of the mixotrophic ciliate Myrionecta rubra in the Columbia River estuary during 2007–2010 was evaluated with biogeochemical, light microscopy, physiological, and molecular data. M. rubra affected surrounding estuarine nutrient cycles, as indicated by high and low concentrations of organic nutrients and inorganic nitrogen, respectively, associated with red waters. M. rubra blooms also altered the energy transfer pattern in patches of the estuarine water that contain the ciliate by creating areas characterized by high primary production and elevated levels of fresh autochthonous particulate organic matter, therefore shifting the trophic status in emergent red water areas of the estuary from net heterotrophy towards autotrophy. The pelagic estuarine bacterial community structure was unaffected by M. rubra abundance, but red waters of the ciliate do offer a possible link between autotrophic and heterotrophic processes since they were associated with elevated dissolved organic matter and showed a tendency for enhanced microbial secondary production. Taken together, these findings suggest that M. rubra red waters are biogeochemical hotspots of the Columbia River estuary.     

The Exploitation of Plant Resources by Early Homo sapiens: The Phytolith Record from Pinnacle Point 13B Cave,South Africa

The capacity to detect remnants of fire usage in archaeological sites, along with a better understanding of its use by prehistoric populations, can help us to shed light on hominin cognition, social organization, and technology. The application of phytolith studies to understand fire and its use can be widely applicable since plants typically contain phytoliths that are identifiable to different taxonomic levels. Pinnacle Point 13B (PP13B) is one of several South African Middle Stone Age (MSA) sites that shows an abundant presence of lenses of burnt material and intact hearths. Phytolith analyses at PP13B have been used to identify the types of plants used as fuel in the hearths. The phytoliths overall show high levels of alteration, and varying alteration is used to identify areas with higher alkaline conditions related to dripping water. In some areas of the site, there is excellent preservation of multicellular structures from the epidermal leaves of dicotyledonous plants, suggesting in situ structures with practically no chemical or post‐depositional alteration. A notable pattern is the abundance of dicotyledonous leaves from the rear of the cave, which might indicate specific leaf‐fuels for the fires, short‐term fire activities, or other actions such as cooking.     

Permeability of JSC-1A: A lunar soil simulant

The permeability of lunar soil simulant, JSC-1A, is measured over a range of bulk densities from 1550 to 2000 kg m⁻³. The corresponding viscous flow permeability is 1 × 10⁻¹² m² to 6.1 × 10⁻¹² m² for this bulk density range. Implications of these values on the contamination of regolith by rockets, on barrier/enhancement to bulk flow of ice, and on cratering are discussed. Although the particle size and shape distribution of the JSC-1A are extremely wide, the permeability measurements agree surprisingly well with the Carman-Kozeny equation. The results provide evidence that the Carman-Kozeny model could be applicable to other naturally occurring soils if effective soil properties are considered.