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Aim This birth cohort study investigated longitudinal infant growth and associated factors in a multiethnic population living in a low‐resource district surrounding the town of Paarl in South Africa. Methods Between March 2012 and October 2014, all mothers attending their second trimester antenatal visit at Paarl Hospital were approached for enrolment. Mother–infant pairs were followed from birth until 12 months of age. Comprehensive socio‐demographic, nutritional and psychosocial data were collected at birth, two, six and 12 months. Infant anthropometry was analysed as z‐scores for weight and height. Linear regression was used to investigate predictors of birthweight, and linear mixed‐effects models were used to investigate predictors of infant growth. Results Longitudinal anthropometric data from 792 infants were included: 53% were Black African, 47% were mixed race, and 15% were born preterm. Stunting occurred in 13% of infants at 12 months. Maternal height, antenatal alcohol and tobacco use, ethnicity and socioeconomic status were significant predictors of birthweight. In the adjusted mixed‐effects model, birthweight was a significant predictor of growth during the first year of life. Conclusion Birthweight was an important predictor of growth trajectory during infancy. Birthweight and growth were influenced by several important modifiable factors.

Social epidemiology is the branch of epidemiology concerned with understanding how social and economic characteristics influence states of health in populations. There has been a resurgence recently in interest among epidemiologists about the roles that social and economic factors play in determining health, leading to valuable synergies with the social sciences. The determinants of health commonly studied in social epidemiology include absolute poverty, income inequality, as well as race and discrimination. Recently, social epidemiologists have been at the forefront of conceptual developments within the discipline that view the determinants of health at different levels of social organization. © 2008 Copyright © 2008 Elsevier Inc. All rights reserved.

Data are scarce regarding surgical and non-surgical education in accredited Female Pelvic Medicine and Reconstructive Surgery (FPMRS) fellowships in theUnited States. We compared surgical and non-surgical and education among training programs and expected surgical comfort level with pelvic reconstructive procedures from the perspective of the fellow and program director. An online survey was distributed to program directors and fellows from the 39 accredited FPMRS fellowships at the time (2010). Domains evaluated in the survey were academic education requirements; surgical approaches to prolapse and to incontinence; other surgical procedures; and research and publication expectations. In total, forty fellows from 21 programs and directors from 27 programs. The most common surgical procedures performed for apical, anterior, and posterior prolapse were uterosacral ligament suspension, native tissue anterior colporrhaphy, and posterior colporrhaphy, respectively. Differences in perceived surgical comfort level were seen for coccygeus suspension, graftreinforced posterior colporrhaphy, rectus fascial sling, urethral bulking agent, cystoscopic ureteral stent placement and bowel repair. A greater proportion of program directors reported that fellows would be comfortable performing these procedures upon graduation than the proportion reported by the fellows themselves. Differences exist in FPMRS training nationwide, however, responding fellows appeared to be trained in multiple approaches to prolapse repair. Differences were seen in surgical comfort level as perceived by fellows and program directors.

Polo-like kinases (Plk1-4) are emerging as an important class of proteins involved in many aspects of cell cycle regulation and response to DNA damage. Here, we report the cloning of a fifth member of the polo-like kinase family named Plk5. DNA and protein sequence analyses show that Plk5 shares more similarities with Plk2 and Plk3 than with Plk1 and Plk4. Consistent with this observation, we show that mouse Plk5 is a DNA damage inducible gene. Mouse Plk5 protein localizes predominantly to the nucleolus, and deletion of a putative nucleolus localization signal (NoLS) within its N-terminal moiety disrupts its nucleolar localization. Ectopic expression of Plk5 leads to cell cycle arrest in G1, decreased DNA synthesis, and to apoptosis, a characteristic it shares with Plk3. Interestingly, in contrast to mouse Plk5 gene, the sequence of human Plk5 contains a stop codon that produces a truncated protein lacking part of the kinase domain.

Polo-like kinases (Plks) are key regulators of the cell cycle, especially in the G2 phase and mitosis. They are incorporated into signaling networks that regulate many aspects of the cell cycle, including but not limited to centrosome maturation and separation, mitotic entry, chromosome segregation, mitotic exit, and cytokinesis. The Plks have well conserved 30-amino-acid elements, designated polo boxes (PBs), located in their carboxyl-termini, which with their flanking regions constitute a functional Polo-box domain (PBD). Members of the Plk family exist in a variety of organisms including Polo in Drosophila melanogaster; Cdc5 in Saccharomyces cerevisiae; Plo1 in Schizosaccharomyces pombe; Plx1 in Xenopus laevis; and Plk1, Snk/Plk2, Fnk/Prk/Plk3, and Sak in mammals. Polo, Cdc5, and Plo1 are essential for viability. The Plks can be separated into two groups according to their functions. The first group (Polo, Cdc5, plo1, Plx1, and Plk1) primarily performs mitotic functions, whereas the second group (Plk2 and Plk3) appears to have additional functions during the G1, S, and G2 phases of the cell cycle. Several contributions to this issue will discuss different aspects of Plk involvement in cell-cycle regulation. This review, therefore, will focus on the role of Plk3 in regulating Cdc25 phosphatase function and its effect on the cell cycle.

The Polo-like kinases (Plks) are a conserved family of kinases that contribute to cell cycle regulation, particularly in G2 and mitosis. In mammals, there are at least three members of the Plk family. Here we show that Plk3 is a stress response protein that becomes phosphorylated following DNA damage or mitotic spindle disruption. Phosphorylation enhances its kinase activity and is dependent upon ataxia telangiectasia-mutated (ATM) in the former case but not the latter. Plk3 associates with complexes of multiple sizes ranging from 150 to greater then 600 kDa. In its unphosphorylated form it elutes from a sizing column at about 400 kDa whereas it associates with complexes of 150 and 600 kDa when phosphorylated. Among the proteins with which it physically associates and utilizes, as substrates are Chk2 and P53. It phosphorylates Chk2 on a residue different from threonine 68 (Thr68), the principal target for ATM. While ATM is necessary for phosphorylation and activation of Chk2 in vivo, Plk3 seems to contribute to its full activation. In its phosphorylated form it also coelutes and forms a complex with unpolymerized tubulin. In aggregate, the data argue that Plk3 is a multifunctional protein that associates with multiple complexes and that contributes to response to stress incurred by DNA damage and mitotic spindle disruption, albeit via different pathways.

Seagrass habitats exhibit high structural variability at local (

The signing of the Convention on Biological Diversity at the ``Earth Summit'' in 1992, its ratification and its subsequent entering into force have highlighted the need for an approach to biodiversity conservation that employs both ex situ and in situ techniques in a complementary manner. Though much research has focused on ex situ techniques, less progress has been made in developing methodologies for the conservation of genetic diversity in situ. The definition of in situ conservation used in the Convention on Biological Diversity encompasses two distinct processes: conservation of wild species in genetic reserves and of crops on-farm. Of these two, the latter, where the genetic diversity of crop land races is conserved within traditional farming systems, has been the less studied and remains less well understood. While there are still relatively few practical examples of on-farm genetic resources conservation, most genetic diversity of immediate and potential use to plant breeders is found among land races, and there is evidence that it is being rapidly eroded. This paper attempts to set on-farm conservation within the context of plant genetic resource conservation as a whole, to introduces a possible generalised model for the conservation of genetic diversity on-farm and to promote debate around the science of on-farm conservation.

The number of HIV positive lesbians is on the rise. Yet, the Centers for Disease Control and Prevention has no statistical category by which to classify female-to-female transmitted AIDS cases. Women who have sex with women have been dismissed as a “low risk” group without the benefit of empirical data. This study used data collected from subscribers of an international lesbian magazine (n = 248) to examine how beliefs held by lesbians may be influencing their risk for contracting HIV. Using the Health Belief Model, it was anticipated that perceived personal risk, knowledge regarding HIV transmission mechanisms, knowing a lesbian with HIV, or having been diagnosed HIV positive would increase the use of safer sex practices. Regression analysis found perceived personal risk, knowing a lesbian with HIV, and educational level significant predictors of barrier use.

Price responsiveness of alfalfa seed demand is estimated using a panel data set of seven Western states, covering the period 1950 to 1992. The demand function is derived from a generalized Leontief variable cost function with a time trend. Tests are performed and corrections are made for heteroskedasticity and serial autocorrelation. Estimated own-price elasticities of demand are highly inelastic, but over time become price sensitive. The estimated cross-price elasticities indicate that machinery price has the highest impact on alfalfa seed demand. An estimate of technological change indicates that the industry has been taking advantage of the improved seed genetics. © 1998 John Wiley & Sons, Inc.

Farms in South Africa have to compete in a very hostile agricultural economic environment and it has become imperative for farmers to find new ways of generating additional income. Research undertaken in the Mopani District Municipality (MDM) in the Limpopo Province of South Africa identified agritourism as a potential means to this end. The main aim of this primarily qualitative study was to gain a better understanding of the perceptions and opportunities for agritourism in the study area. Data were mainly collected through interviews and questionnaires. Participants consisted of farmers and tourists, as well as owners of existing agritourism farms within the MDM. Five current active agritourism establishments were identified. Key fidnings revealed that agritourism is not being utilised to its full potential. Although perceptions of respondents towards agritourism are positive, marketing around it is insufficient and not all farmers are willing to host agritourism activities on their farms for various reasons. However, the MDM is a tourist hub with many visitors passing through various reasons. However, the MDM is a tourist hub with many visitors passing through the area en route to the Kruger National Park. Therefore, the potential already exists to host agritourism activities that will benefit farmers in various ways. By developing farm trails, scheduling daily farm activities, using information brochures, forming networks with existing tourist establishments, encouraging the use of local and fresh produce and providing good roadside signage, farmers can gain increased exposure and recognition for what they do and opportunities for growth and development may be realised. Keywords: Agritourism, farm tourism, alternative tourism, farm activities, tourism

Managing irrigation water to replace soil moisture depletion is equivalent to managing water for yield maximization, and does not constitute efficient resource use. Irrigation water allocation models should be based on profit maximization, which will occur at the same point that maximizes water use efficiency. The objectives of this study were to: (i) optimize water allocation based on profit maximization; and (ii) compare curvilinear and linear water production functions for profit maximization. Water production functions were developed for four seasonal harvests of alfalfa (Medicago sativa L.) from data collected over a 6-yr field research project conducted at the University of Nevada, Reno [...]

The polo-like kinases (Plks1-5) are emerging as an important class of proteins involved in many facets of cell cycle regulation and response to DNA damage and stress. Here we show that Plk3 phosphorylates the key cell cycle protein phosphatase Cdc25A on two serine residues in its cyclinB/cdk1 docking domain and regulates its stability in response to DNA damage. We generated a Plk3 knock-out mouse and show that Cdc25A protein from Plk3-deficient cells is less susceptible to DNA damage-mediated degradation than cells with functional Plk3. We also show that absence of Plk3 correlates with loss of the G1/S cell cycle checkpoint. However, neither this compromised DNA damage checkpoint nor reduced susceptibility to proteasome-mediated degradation after DNA damage translated into a significant increase in tumor incidence in the Plk3-deficient mice.

Background: To evaluate the skill of fifth-year medical students at the University of Cape Town in the performance of fundoscopy at the end of their ophthalmology rotation.Methods: The design was a prospective cohort study. The study was conducted at Groote Schuur Hospital in Cape Town. The ability of fifth-year medical students to perform fundoscopy on mannequin heads fitted with fundus photographs using direct ophthalmoscopes was evaluated. The outcome measures used were ability to see the fundus and ability to recognise fundus pathology.Results: The fundus photographs could be seen in 95% of cases. The correct diagnosis could be made in only 57% of cases.Conclusion: Medical students at the University of Cape Town need more than the current one week of practical ophthalmology training to improve their fundoscopy skills.Keywords: primary health eye care; teaching fundoscopy; essential basic medical skill; medical student training

(.)The objective of this study were to: develop a production function that includes irrigation water and crop evapotranspiration as variables; and estimate individual harvest water production functions and determine if they are statistically different. Yield data were derived from four different water application rates based on 50, 75, 100 and 125% of FAO modified pan evaporation (.)

Tuberculosis (TB) preventive therapy is not effective in human immunodeficiency virus (HIV) infected adults with negative tuberculin skin tests (TSTs). However, there are insufficient data on patients with advanced HIV disease from high TB incidence areas.We conducted a randomised, double-blind, controlled trial comparing isoniazid (INH) with placebo among TST-negative adults with World Health Organization Stage 3 or 4 HIV disease. INH/placebo was administered for 12 months by patient-nominated supervisors. TST-positive participants were given open-label INH. Participants, who did not have access to antiretroviral therapy (ART), were followed up for 24 months with 6-monthly sputum culture and chest radiography.A total of 118 participants were enrolled: TST was negative in 98. In the randomised arms, the incidence of TB was 18/100 person-years (py) in the INH arm and 11.6/100 py in the placebo arm (hazard ratio 1.59, 95%CI 0.57-4.49). There were no significant differences in mortality, hospitalisation rate or CD4+ lymphocyte decline. INH/placebo adherence was 85%, and was significantly higher among participants with work-based treatment supervisors.We did not find any association between INH preventive therapy and reductions in incident TB among TST-negative adults with advanced HIV disease, but the study had limited statistical power. High levels of adherence were observed with patient-nominated supervisors.

The tumor suppressor gene Chk2 encodes a serine/threonine kinase that signals DNA damage to cell cycle checkpoints. In response to ionizing radiation, Chk2 is phosphorylated on threonine 68 (T68) by ataxia-telangiectasia mutated (ATM) protein leading to its activation. We have previously shown that polo-like kinase 3 (Plk3), a protein involved in DNA damage checkpoint and M-phase functions, interacts with and phosphorylates Chk2. When Chk2 was immunoprecipitated from Daudi cells (Plk3-deficient), it had weak kinase activity towards Cdc25C compared with Chk2 derived from T47D cells (Plk3-expressing cells). This activity was restored by addition of recombinant Plk3 in a dose-dependent manner. Plk3 phosphorylates Chk2 at two residues, serine 62 (S62) and serine 73 (S73) in vitro, and this phosphorylation facilitates subsequent phosphorylation of Chk2 on T68 by ATM in response to DNA damage. When the Chk2 mutant construct GFP-Chk2 S73A (serine 73 mutated to alanine) is transfected into cells, it no longer associates with a large complex in vivo, and manifests a significant reduction in kinase activity. It is also inefficiently activated by ATM by phosphorylation at T68 and, in turn, is unable to phosphorylate the Cdc25C peptide 200-256, which contains the inhibitory S216 target phosphorylation residue. As a consequence, tyrosine 15 (Y15) on Cdc2 remains hypophosphorylated, and there is a loss of the G2/M checkpoint. These data describe a functional role for Plk3 in a pathway linking ATM, Plk3, Chk2, Cdc25C and Cdc2 in cellular response to DNA damage.

As part of the USDOE Natural Gas Program, LBNL is the lead institution in a multi-institutional project ( Conoco, Lynn Inc., Schlumberger, Stanford and Virginia Tech.) which is developing methods for mapping fractures that control flow in naturally fractured gas reservoirs. The work has progressed from lab studies to controlled field studies and now to full scale application in the San Juan Basin in New Mexico. This paper is a summary of the latest field efforts in the spring of 2002 to apply high resolution methods (logging (including FMI, cross dipole), single well seismic, and VSP) in order to compare to the results of previous 3-D surface P-wave imaging. The goal is to develop new methodology that can be applied at all scales and determine the optimum scale for each method for not only locating the fractures but quantifying the fracture properties such that the fractures controlling the main permeability can be identified.

Format This is a copy of the slides presented at the meeting but not formally written up for the volume. Abstract Targeting potent anti-cancer therapeutics to solid tumors is best accomplished by first avoiding recognition and uptake by the immune system and second by limiting the biodistribution of the drug to the tumor. We have achieved these objectives by binding tumor necrosis factor alpha (TNF) to the surface of 30 nm pegylated colloidal gold particles. Pegylation of the gold nanoparticles is accomplished by binding thiolated polyethylene glycol in between the TNF molecules on the surface of the gold nanoparticles. This formulation is termed CYT-6091 (Aurimune). The liver or spleen (the RES) take-up little or no drug 6 hr after CYT-6091 is injected into mice, and TNF levels in the tumors increase over this time period (in contrast to decreasing levels of TNF seen in healthy tissues). Electron micrographs also show gold nanoparticles in the tumors, but few or no particles in healthy tissue. By getting more TNF to the tumors, CYT-6091 is both safer and more effective in causing tumor regression in mice. CYT-6091 has also been given to dogs with naturally occurring cancers. Most notably in both dogs with cancer and in healthy rabbits, CYT-6091 caused fever, but did not induce hypotension. Historically, hypotension has been the dose-limiting toxicity for TNF and the primary reason for its failure in human clinical trials. For human testing, the manufacturing of CYT-6091 was successfully scaled-up and produced under cGMP. CYT-6091 is currently being tested in end-stage disease cancer patients in an NCI sponsored Phase I clinical trial.

This report is a description of the design study for a pilot-scale field demonstration of the Viscous Liquid Barrier (VLB) technology, a new subsurface containment technology for waste isolation using a new generation of barrier liquids. The demonstration site was Retention Basin 281-3H, a shallow catchment basin at the Savannah River Site, which is contaminated mainly by radionuclides ({sup 137}Cs, {sup 90}Sr, and {sup 238}Pu). The goals of the field demonstration were (a) to demonstrate the ability to create a continuous subsurface barrier in order to isolate the contaminants, and (b) to demonstrate the continuity, performance, and integrity of the barrier. The site was characterized, and preliminary hydraulic conductivity data were obtained from core samples. Based on the site characteristics and the functional requirements, a conceptual model was developed, the barrier specifications were defined, and lance injection was selected as the emplacement method. The injection strategy for the subsurface conditions at the site was determined using numerical simulations. An appropriate variant of Colloidal Silica (CS) was selected as the barrier liquid based on its relative insensitivity to interactions with the site soils, and the formulation for optimum site performance was determined. A barrier verification strategy, including hydraulic, pneumatic, tracer, and geophysical methods, was developed. A lance water injection test was conducted in order to obtain representative estimates of the hydraulic conductivity and its distribution for the design of the barrier emplacement. The water injection test demonstrated the lack of permeable zones for CS injection, and a decision not to proceed with the barrier emplacement was reached.

A pilot-scale field demonstration of waste isolation using viscous- liquid containment barriers has been planned for the 281-3H retention basin at the Savannah River Site, Aiken, SC. The 281-3H basin is a shallow retention/seepage basin contaminated mainly by radionuclides. The viscous-liquid containment barrier utilizes the permeation of liquid grout to either entomb the contaminants within a monolithic grout structure or to isolate the waste by drastically reducing the permeability, of the soils around the plume. A clear understanding of the hydrogeologic setting of the retention basin is necessary for proper design of the viscous liquid barrier. To aid in the understanding of the hydrogeology of the 281-3H retention basin, and to obtain critical parameters necessary for grout injection design, a series of tests were undertaken in a region immediately adjacent to the basin. The objectives of the LWIT were: 1. To evaluate the general performance of the Lance Injection Technique for grout emplacement at the site, including the range and upper limits of injection pressures, the flow rates applicable for site conditions, as well as the mechanical forces needed for lance penetration. 2. To obtain detailed information on the injectability of the soils immediately adjacent to the H-area retention basin. 3. To identify any high permeability zones suitable for injection and evaluate their spatial distribution. 4. To perform ground penetrating radar (GPR) to gain information on the structure of the soil column and to compare the results with LWIT data. This report will focus on results pertinent to these objectives.

This report is the design study for a medium-scale field demonstration of Lawrence Berkeley National Laboratory`s new subsurface containment technology for waste isolation using a new generation of barrier liquids. The test site is located in central California in a quarry owned by the Los Banos Gravel Company in Los Banos, California, in heterogeneous unsaturated deposits of sand, silt, and -ravel typical of many of the and DOE cleanup sites and particularly analogous to the Hanford site. The coals of the field demonstration are (a) to demonstrate the ability to create a continuous subsurface barrier isolating a medium-scale volume (30 ft long by 30 ft wide by 20 ft deep, i.e. 1/10th to 1/8th the size of a buried tank at the Hanford Reservation) in the subsurface, and (b) to demonstrate the continuity, performance, and integrity of the barrier.

3586 Background: CYT-6091 is the first tumor-targeted nanomedicine formulation designed to safely deliver an API that itself is not approved for systemic administration due to unacceptable toxicity. CYT-6091, consisting of tumor necrosis factor-α (TNF) covalently linked to pegylated colloidal gold nanoparticles, has been safely administered in preclinical models, demonstrating an increased T1/2 compared to native TNF, a documented trafficking of nanoparticles to tumor, and no hypotension, the known DLT for TNF. Methods: CYT-6091 was tested in a phase I open label trial in solid tumor, advanced stage patients. Patients (n = 3/dose), admitted to the NIH Clinical Center ICU, received two IV injections of CYT-6091 on day 0 and 14. Dosing started at 50 μg/m2 of TNF, up to 600 μg/m2. Vital signs were monitored and blood samples were drawn over 48 h. The primary endpoint of the study was to determine the MTD for CYT-6091. Secondary endpoints included PK, disease response (staged 45 days post treatment by RECIST), and the detection of gold nanoparticles in tumors and in adjacent healthy tissue. Results: Twenty-nine patients were treated. Even at the lowest dose (50 μg/m2), patients exhibited a febrile response, which was mitigated by acetaminophen and indomethacin pretreatment. None of the 29 patients treated with doses of 50–600 μg/m2 showed a DLT hypotensive response, and in fact, no DLT was seen. T1/2 estimates for TNF, administered as CYT-6091, are 120, 131, 127, 146, 112, 113, 266, 371, and 160 minutes for 50, 100, 150, 200, 250, 300, 400, 500, 600 μg/m2, respectively (published T1/2 for native TNF is ∼27 minutes). In the 28 patients eligible for response assessment, there was 1 PR (100 μg/m2 dose, 7 months duration) and 3 SD (2, 2, and 3 months duration). Electron micrographs show gold nanoparticles in tumor biopsies. Conclusions: CYT-6091 is well tolerated at doses up to 600 μg/m2 of TNF, levels 3-times greater than the published MTD for native TNF. CYT-6091 targets tumors in humans. Efficacy studies in combination with chemotherapy are planned. [Table: see text]

3603 Background: CYT-6091, a nanotherapeutic manufactured by covalently linking tumor necrosis factor-a (TNF) onto the surface of 30 nm particles of pegylated colloidal gold, avoids uptake by the reticuloendothelial system (RES) and distributes primarily to solid tumors. In tumor bearing mice, CYT-6091 shows little to no uptake by the RES and increases intra-tumor TNF levels 10-fold. Electron micrographs show the accumulation of gold nanoparticles in tumors, with few particles in healthy tissue. In dogs with naturally occurring cancers and healthy rabbits, CYT-6091 caused fever but no hypotension, the known DLT for TNF. Methods: CYT-6091 is being tested in a phase I open label trial in solid tumor, advanced stage disease patients. Patients (n=3/dose), admitted to the NIH Clinical Center ICU, receive two IV injections of CYT-6091 on day 0 and 14. Doses start at 50 μg/m2 of TNF and increase by 50 μg/m2 increments to 300 μg/m2. Vital signs are monitored and blood samples are drawn over 48 hours. The primary endpoint of the study is to determine the MTD for CYT-6091. Secondary endpoints include PK, disease response (staged 45 days post treatment), and the detection of gold nanoparticles in tumors and in adjacent healthy tissue. Results: Seven patients have been treated to date. The three treated with the lowest dose (50 μg/m2) exhibited a febrile response, which was mitigated by acetaminophen and indomethacin pretreatment. None of the seven patients treated with 50, 100 or 150 μg/m2 showed a DLT hypotensive response, and blood chemistries and urinalysis were not significantly different following treatment. PK estimates for the TNF T1/2, administered as CYT-6091, are 117, 145 and 127 minutes for 50, 100 and 150 μg/m2, respectively. Electron micrographs of tumor biopsies and adjacent healthy tissue show as much as a 10-fold increase in the number of gold nanoparticles in tumors from 5 of 6 patients compared to adjacent healthy tissue. Conclusion: These observations are the first definitive demonstration in man of the tumor targeting of a systemically administered, colloidal gold-based nanomedicine. No significant financial relationships to disclose.

The Tax Reform Act of 1986 has been shown to greatly impact after-tax net farm incomes for sole proprietor agricultural enterprises. Capitalization of these income reductions into land values of a typical Western beef cattle ranch is assessed in this article. Total effects of the Act may decrease the value of a typical ranch by 40%.

Research of extreme importance in the field of electric welding is reviewed briefly in this progress report. Laboratory tests have demonstrated the impossibility to strike an arc with 1 2 0 volts between pure iron electrodes in an atmosphere of pure argon, an observation that may require the modification of basic conceptions of the nature of the electric arc discharge

An assessment was performed of existing mathematical models for subsidence simulation and prediction. Detailed analyses are presented of the theory, power, usability, and performance of the seven models used in conjunction with an ongoing research program aimed at improved understanding and control of ground movements caused by geothermal power production. The models used were: hand-calculation techniques; the nucleus-of-strain method; the one-dimensional Terzaghi consolidation method; the two-dimensional boundary-integral-equation method; two-dimensional finite-element coupled fluid flow and deformation; three-dimensional integrated finite difference, coupled fluid flow, heat flow, and porosity change; and the three-dimensional displacement discontinuity method. (MHR)

The data base developed for selection and evaluation of geothermal subsidence case studies is presented. Data from this data base were used in case studies of Wairakei, The Geysers, and Austin Bayou Prospect (Report LBL 10571).

There are a variety of theories, techniques, and parameters in the subsidence literature. Biot's theory, Terzaghi's theory, and the theory of interacting continua (TINC) are used to explain solid-fluid interaction; stress-strain theories range from linear elastic to e-log p to plasticity and pore-collapse theories. Parameters are numerous: void ratio,, permeability, compaction coefficient, pore compressibility, Young's modulus, bulk modulus, shear modulus, Poisson's ratio, Lame coefficients, coefficient of consolidation, and storage coefficient. The physical processes which govern compaction and deformation in geothermal systems are reviewed. The review is an attempt to provide a reasonably coherent general structure for the theories and parameters which were referred to above. The materials presented is a compendium of existing published work.

In 1978, Congress passed the Energy Tax Act which, in addition to the 10% investment tax credit then available, added a 10% tax credit (increased to 15% by the Crude Oil Windfall Profits Tax Act of 1980) to specifically encourage industrial investment in equipment which either generated energy from renewable sources or conserved energy. The purpose of this study is to estimate the amount of renewable energy investment these tax credits will cause, if they are retained until 1991, and to estimate the net costs to the US Tresury of providing these tax credit programs. The effect of increasing the level of renewable energy tax credit program from 15 to 30, 45, or 60% was also considered. In addition, the current tax credit program and the at-risk provision of tax law were examined and their impact on renewable energy investment considered. The present situation, the anticipated effects of preserving the present tax credit policy, and the probable effects of changing tax credit policy to further encourage renewable energy investment are examined. The findings on each of these issues are summarized.

The results of an assessment of existing mathematical models for subsidence simulation and prediction are summarized. The following subjects are discussed: the prediction process, physical processes of geothermal subsidence, computational models for reservoir flow, computational models for deformation, proficiency assessment, and real and idealized case studies. (MHR)