The Mars ancient cratered terrain, smooth plains boundary: Implications of Viking color data for evolution of the Amenthes Region

The global color set compiled by the Mars Consortium was investigated. The problem of application of the martian surface color data to geologic interpretation are atmospheric contributions which increase with latitude, and the high correlation among the three color bands. In southern Amenthes the classified units show areas of possible mixing between cratered tarrain and smooth plains. It is suggested that some geologically meaningful correlation exists between surface units and the transformed color data in the Amenthes region. The knobby terrain protruding through the plains units appears to be remnants of ancient cratered terrain extending northward beneath the more youthful smooth plains

Pacific Herring, Clupea pallasi, spawning population assessment for San Francisco Bay, 1992-93

We conducted hydroacoustic surveys, spawn surveys, and sampled schools and fishery landings from 8 November 1992 through 18 March 1993 to assess the status of San Francisco Bay's Pacific herring spawning population. Our spawning biomass estimate of 21,186 tons is the lowest since 1978 when subtidal spawns were included in estimates; it also represents a third consecutive season of decline. The principal reason for this very low estimate is a lack of two-, three-, and four-year-old herring in the spawning population from the 1991,1990, and 1989 year-classes. Although four-year-olds were the most abundant cohort, their actual number was very low. Five-year-olds from the highly successful 1988 year-class were the second most abundant cohort. Warm-water conditions and poor upwelling associated with the 1991-92 El Nino are likely causes of the low spawning biomass, although adverse impacts on the condition and growth of spawners were not apparent. Warm water may have displaced herring to the north of San Francisco Bay. We also continued to collect data for a herring young-of-the-year abundance index during April, May, and June of 1993. The index was low for the 1990 and 1991 year-classes, but high for the 1989 year-class. The 1989 and 1990 year-classes appear poor; however, the success of the 1991 year-class will not be known until next season when it fully recruits to the spawning population.The index for the 1992 year-class is relatively low as is the index for 1993. The season's 5,555-ton quota (based on the previous season's biomass estimate) exceeded our harvest goal of no more than 20% of spawning biomass for the first time since the 1970s. The number of three-year-old fish in gill net catches increased substantially this season, possibly indicating the use of smaller mesh. Because of the extremely low spawning biomass and uncertainty about future recruitment, our recommendation to the Fish and Game Commission was to close the herring roe fishery in San Francisco Bay until the season following a spawning biomass estimate of 26,000 tons. (30pp.

Pacific herring, Clupea pallasi, spawning population assessment and fishery management for San Francisco Bay, 1993-94

Since the inception of a sac-roe fishery for Pacific herring, Clupea pallasi, in 1973, the California Department of Fish and Game (Department) has annually assessed the status of the state's two largest spawning populations of herring in Tomales and San Francisco Bays. Each year the Department's Pacific Herring Research Project estimates spawning biomass, determines the age structure of the spawning population, examines growth and general condition, estimates the relative abundance of young-of-the-year herring, and monitors the biological aspects of the catch. This information, along with environmental factors, is considered and used to set the harvest quota for the following season's fishery. San Francisco Bay supports the largest spawning population of Pacific herring in California, as well as the largest commercial herring fishery. Spawning generally occurs from November through March, in the intertidal and shallow subtidal zones of the central and southern regions of the Bay. This report presents work conducted during the 1993-94 spawning season and continues the time series of information for the San Francisco Bay spawning population. (36pp.

A Mathematical Hydrodynamic Circulation Model of Great Salt Lake for Resource Management

In the Great Basin region of this country, the resource which has always been of great importance is water. In Utah, the proper management of the resources of Great Salt Lake and the watersheds tributary to it, has become a topic of increasing concern. Recently, much emphasis has been placed on developing the recreational and industrial resources of Great Salt Lake. For optimum economic and social benefits from future development plans, the lake and its tributary watersheds need to be considered in terms of a single entity. In this regard, the Utah Water Research Laboratory (UWRL) has conducted several studies which involve hydrologic basins tributary to Great Salt Lake. Significantly lacking, however, was a comprehensive study of Great Salt Lake itself. The reserach reported herein is directed towards the development of a comprehensive predictive hydrodynamic model of Great Salt Lake (see Figure 1). This model provides two general types of information. First, it provides circulation patterns within the lake for configurations and conditions imposed by the planner. This information is necessary to predict movement of pollutants, paths of freshwater inflows, and other phenomena which depend on currents. Second, the model provides information on the distribution of salinity throughout the lake. This informatino is vital to the industries around the lake which extract minerals from the brines of the lake. These capabilities of the model will also be valuable in providing data to be used by quality models. It could be argued that because of a lack of field data for model verification, the development of a mathematical model was premature. Some field data on salinity are being collected regularly and the data base is steadily growing. Hopefully, the Utah Separtment of Natural Resources will implement a program of measuring velocities and circulation patterns to provide a data base for calibrating the hydraulic model. In any case, the initial development of a mathematical model is appropriate so that over the next few years, it can be improved and adjusted as more data become available. It seemed unwise to wait for a complete data base before launching a lengthy program of development of a mathematical model. The objectives of the research were as follows: 1. To develop new mathematical models or incorporate existing models of the flow through the Southern Pacific causeway embankment and culverts to act as boundary conditions in mathementical circulation models of the southern and northern arms of the Great Salt Lake. 2. To develop an upper-layer hydrodynamic circulation model of Great Salt Lake. As a first step toward developing a more comprehensive two-layer model, it was recognized that the main function of the lower layer within the lake may be to act as a reservoir for passing salinity from the north arm to the surface layer in the south arm. If this is indeed the case, then an upper-layer model could be constucted based on the assumption that the interface is a horizontal boundary which feeds salinity itno the upper layer in some reasonable fashion to maintain continuity. 3. To attempt to develop a coupled two-layer model of Great Salt Lake. It was proposed to use the finite element technique to generate a hydrodynamic model of the circulation patterns in both the upper and lower layers. The finite element representation incorporates cubic velocity variations in the two layers to more accurately simulate the recircualtion flow patterns caused by wind action on the surface and fresh water flow from the contributing streams. 4. To perform a laboratory experiment devised to evaluate the rate of salinity exchange from the lower high-density layer through the interfacial shear zone into the upper layer. It was believed that the exchange of salinity between the two layers is a direct function of the intensity of the interfacial shear and the resulting turbulent mixing at the interface. 5. To attempt to adjust the model to Great Salt Lake. All available velocity and salinity concentration data collected by the United States Geological Survey (USGS) and the Utah Geological and Mineral Survey (UGMS) during recent years was used. 6. To cooperate with researchers who are studying other aspects of the lake by making the mathematical model available to them. A modeling appraoch utilizing equations based on the fundamental laws of physics, coupled with the application of the versatile finite element method gives the hydrodynamic and convetion-dispersion models of Great Salt Lake the versatility required to examine the spectrum of management alternatives. The predictive capability is greatly enhanced in this approach by minimizing the number of empirical constants to be evlatued. It seems clear that the development of these comprehensive models of the lake is a necessary step in the subsequent development and use of both water quality and management models of this important natural resource

Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 13: Injection therapies, low-back pain, and lumbar fusion

pre-printThe medical literature continues to fail to support the use of lumbar epidural injections for long-term relief of chronic back pain without radiculopathy. There is limited support for the use of lumbar epidural injections for short-term relief in selected patients with chronic back pain. Lumbar intraarticular facet injections are not recommended for the treatment of chronic lower-back pain. The literature does suggest the use of lumbar medial nerve blocks for short-term relief of facet-mediated chronic lower-back pain without radiculopathy. Lumbar medial nerve ablation is suggested for 3-6 months of relief for chronic lower-back pain without radiculopathy. Diagnostic medial nerve blocks by the double-injection technique with an 80% improvement threshold are an option to predict a favorable response to medial nerve ablation for facet-mediated chronic lower-back pain without radiculopathy, but there is no evidence to support the use of diagnostic medial nerve blocks to predict the outcomes in these same patients with lumbar fusion. There is insufficient evidence to support or refute the use of trigger point injections for chronic lower-back pain without radiculopathy

Improving access to and engagement with mental health services among young people from refugee backgrounds: service user and provider perspectives

Limited research has been conducted worldwide on the experiences that children and young people from refugee backgrounds have with mental health services, despite evidence that they have significant vulnerability to the development of mental health problems and to suicidal behaviour and that those with mental ill-health typically underutilise services. The authors were particularly interested in barriers and facilitators to service access and engagement, and conducted two qualitative research projects to improve understanding of the issues – the first with service providers experienced in the refugee area and the second with young refugee service users. The aim of this project was to compare the perspectives of professionals and service users and to identify similarities and differences. The perspectives of the service users and providers were strikingly similar. The analysis identified 21 implications for policy makers, agencies and practitioners, which ranged from issues concerning cultural sensitivity, background matching and mental health literacy to accessibility, setting boundaries and expectations and implementing a holistic and outreach approach. There is a range of specific, practical measures that policy makers and service providers can introduce to enhance access to and engagement with mental health services for young people from refugee backgrounds

Thermal perturbations caused by large impacts and consequences for mantle convection

We examine the effects of thermal perturbations on a convecting layer of incompressible fluid with uniform viscosity in the limit of infinite Prandtl number, for two upper boundary conditions (free- and no-slip) and heat sources (100% volumetric heating and 100% bottom heating) in 2-D Cartesian finite element simulations. Small, low-temperature perturbations are swept into nearby downflows and have almost no effect on the ambient flow field. Large, high-temperature perturbations are rapidly buoyed and flattened, and spread along the layer\u27s upper boundary as a viscous gravity current. The spreading flow severs and displaces downwellings in its path, and also thins and stabilizes the upper thermal boundary layer (TBL), preventing new instabilities from growing until the spreading motion stops. A return flow driven by the spreading current displaces the roots of plumes toward the center of the spreading region and inhibits nascent plumes in the basal TBL. When spreading halts, the flow field is reorganized as convection reinitiates. We obtain an expression for the spreading time scale, ts, in terms of the Rayleigh number and a dimensionless perturbation temperature (Θ), as well as a size (Λ), and a condition that indicates when convection is slowed at a system-wide scale. We also describe a method for calculating the heat deposited by shock waves at the increased temperatures and pressures of terrestrial mantles, and supply estimates for projectile radii in the range 200 to 900 km and vertical incident velocities in the range 7 to 20 km s−1. We also consider potential applications of this work for understanding the history of early Mars