A Study of Soil Erosion on a Steep Cultivated Slope in the Mt. Gongga Region near Luding, Sichuan, China, using the 137 Cs Technique

This paper reports the results of an investigation of soil erosion on a steep cultivated slope in the Mt Gongga region of the Upper Yangtze River Basin, Southwest China, using the 137Cs technique. The effective 137Cs reference inventory for the study field, estimated from the bottom layer of a 137Cs depth profile at the deposition zones, is 2373.9 Bq/m2, accounting for 65.8% the local 137Cs reference inventory of 3607.7 Bq/m2. It strongly indicates that a considerable amount of 137Cs input was lost prior to incorporation into the ploughing layer from the study field during the nuclear weapons testing period because of 137Cs surface enrichment. The average erosion rate is estimated to be 4914 t/km2 yr for a typical cultivated steep slope with an angle of 34°at the subtropical zone in the Mt Gongga region. It can reach to 22856 t/km2 yr for a failure slope under cultivation

Transport between edge states in multilayer integer quantum Hall systems: exact treatment of Coulomb interactions and disorder

A set of stacked two-dimensional electron systems in a perpendicular magnetic field exhibits a three-dimensional version of the quantum Hall effect if interlayer tunneling is not too strong. When such a sample is in a quantum Hall plateau, the edge states of each layer combine to form a chiral metal at the sample surface. We study the interplay of interactions and disorder in transport properties of the chiral metal, in the regime of weak interlayer tunneling. Our starting point is a system without interlayer tunneling, in which the only excitations are harmonic collective modes: surface magnetoplasmons. Using bosonization and working perturbatively in the interlayer tunneling amplitude, we express transport properties in terms of the spectrum for these collective modes, treating electron-electron interactions and impurity scattering exactly. We calculte the conductivity as a function of temperature, finding that it increases with increasing temperature as observed in recent experiments. We also calculate the autocorrelation function of mesoscopic conductance fluctuations induced by changes in a magnetic field component perpendicular to the sample surface, and its dependence on temperature. We show that conductance fluctuations are characterised by a dephasing length that varies inversely with temperature.Comment: 13 pages, 10 figures, minor changes made for publicatio

Do female association preferences predict the likelihood of reproduction?

Sexual selection acting on male traits through female mate choice is commonly inferred from female association preferences in dichotomous mate choice experiments. However, there are surprisingly few empirical demonstrations that such association preferences predict the likelihood of females reproducing with a particular male. This information is essential to confirm association preferences as good predictors of mate choice. We used green swordtails (<i>Xiphophorus helleri</i>) to test whether association preferences predict the likelihood of a female reproducing with a male. Females were tested for a preference for long- or short-sworded males in a standard dichotomous choice experiment and then allowed free access to either their preferred or non-preferred male. If females subsequently failed to produce fry, they were provided a second unfamiliar male with similar sword length to the first male. Females were more likely to reproduce with preferred than non-preferred males, but for those that reproduced, neither the status (preferred/non-preferred) nor the sword length (long/short) of the male had an effect on brood size or relative investment in growth by the female. There was no overall preference based on sword length in this study, but male sword length did affect likelihood of reproduction, with females more likely to reproduce with long- than short-sworded males (independent of preference for such males in earlier choice tests). These results suggest that female association preferences are good indicators of female mate choice but that ornament characteristics of the male are also important

The grain size characteristics of overbank deposits on the floodplains of British lowland rivers

Abstract River flood plains are attracting increasing attention because of their wideranging environmental significance. In the UK, little is currently known regarding the grain size composition of the fine-grained overbank deposits that dominate most lowland river flood plains. This paper reports the findings of a study aimed at investigating the grain size composition of the overbank flood plain deposits assoc iated with the flood plains of six rivers in southern Britain, embracing a range of catchment characteristics and hydrological conditions. More than 900 cores were collected from representative reaches along the flood plains of the six rivers and their grain size composition was determined. Analysis of the results obtained focuses on contrasts between the rivers, on within-reach and longitudinal variability in grain size composition and on the relationship between grain size composition and sedimentation rate

Two Mental Models of integrated Care For advanced Liver Disease: Qualitative Study of Multidisciplinary Health Professionals

OBJECTIVES: The purpose of this paper is to present two divergent mental models of integrated advanced liver disease (AdvLD) care among 26 providers who treat patients with AdvLD. SETTING: 3 geographically dispersed United States Veterans Health Administration health systems. PARTICIPANTS: 26 professionals (20 women and 6 men) participated, including 9 (34.6%) gastroenterology, hepatology, and transplant physicians, 2 (7.7%) physician assistants, 7 (27%) nurses and nurse practitioners, 3 (11.5%) social workers and psychologists, 4 (15.4%) palliative care providers and 1 (3.8%) pharmacist. MAIN OUTCOME MEASURES: We conducted qualitative in-depth interviews of providers caring for patients with AdvLD. We used framework analysis to identify two divergent mental models of integrated AdvLD care. These models vary in timing of initiating various constituents of care, philosophy of integration, and supports and resources needed to achieve each model. RESULTS: Clinicians described integrated care as an approach that incorporates elements of curative care, symptom and supportive care, advance care planning and end-of-life services from a multidisciplinary team. Analysis revealed two mental models that varied in how and when these constituents are delivered. One mental model involves sequential transitions between constituents of care, and the second mental model involves synchronous application of the various constituents. Participants described elements of teamwork and coordination supports necessary to achieve integrated AdvLD care. Many discussed the importance of having a multidisciplinary team integrating supportive care, symptom management and palliative care with liver disease care. CONCLUSIONS: Health professionals agree on the constituents of integrated AdvLD care but describe two competing mental models of how these constituents are integrated. Health systems can promote integrated care by assembling multidisciplinary teams, and providing teamwork and coordination supports, and training that facilitates patient-centred AdvLD care

Measurement component technology. Volume 3: Cryogenic temperature measurement and high temperature strain gage technology

For abstract, see N74-27185

Description and dosimetric verification of the PEREGRINE Monte Carlo dose calculation system for photon beams incident on a water phantom

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134919/1/mp1551.pd

Late Quaternary evolution of a lowland anastomosing river system: Geological-topographic inheritance, non-uniformity and implications for biodiversity and management

Lowland multiple-channel rivers are characterised by floodplain-corridor heterogeneity, high ecological and heritage value, and can be in quasi-stable states. This holistic study of a surviving temperate zone example (Culm, UK) uses geomorphological mapping, 14C, direct sediment dating (OSL, fallout radionuclides), and palaeoecology. This reveals the evolution of a channel-floodplain system from an initial braided state in the Late Pleistocene to its late Holocene anastomosing state. After the Pleistocene Holocene transition the reduced channel system incised into its braid-plain, only able to rework gravels locally due to reduced competence in relation to inherited bounding sediment calibre. This resulted in the creation of terrace islands, palaeochannels, and a stable anastomosing pattern dominated by channel junctions, bifurcations and palaeochannel intersections. Survey, coring and excavation reveal a persistence of mid-channel bars and riffles at channel junctions, and where channels crossed palaeochannel fills. In common with most other European lowland rivers this system evolves in the later Holocene due to both climate and catchment changes with a major hydrological critical transition in the mid-Holocene (c. 5300 BP). However, in the case of the Culm, the increase in fine sediment supply often seen in lowland catchments in the Middle-Late Holocene, occurred later, and was insufficient to convert the system to a single medium-low sinuosity channel-floodplain. This allowed the persistence of high heterogeneity and biodiversity (including the persistence of riffle beetles) as part of multiple-scales of non-uniformity. Indeed the pool-riffle persistence is an example of this system’s non-uniformity, being due, at least in part, to the effects of previous channel history. This paper reveals why this river survived in a multichannel state, and by implication, why others did not. These results are being used in the bespoke eco-heritage management of the Culm, but could also inform the restoration of other former multi-channel lowland temperate river systems worldwide