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1.
Lancet Respir Med ; 12(8): 599-607, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38701817

RESUMEN

BACKGROUND: Delirium is common during critical illness and is associated with long-term cognitive impairment and disability. Antipsychotics are frequently used to treat delirium, but their effects on long-term outcomes are unknown. We aimed to investigate the effects of antipsychotic treatment of delirious, critically ill patients on long-term cognitive, functional, psychological, and quality-of-life outcomes. METHODS: This prespecified, long-term follow-up to the randomised, double-blind, placebo-controlled phase 3 MIND-USA Study was conducted in 16 hospitals throughout the USA. Adults (aged ≥18 years) who had been admitted to an intensive care unit with respiratory failure or septic or cardiogenic shock were eligible for inclusion in the study if they had delirium. Participants were randomly assigned-using a computer-generated, permuted-block randomisation scheme with stratification by trial site and age-in a 1:1:1 ratio to receive intravenous placebo, haloperidol, or ziprasidone for up to 14 days. Investigators and participants were masked to treatment group assignment. 3 months and 12 months after randomisation, we assessed survivors' cognitive, functional, psychological, quality-of-life, and employment outcomes using validated telephone-administered tests and questionnaires. This trial was registered with ClinicalTrials.gov, NCT01211522, and is complete. FINDINGS: Between Dec 7, 2011, and Aug 12, 2017, we screened 20 914 individuals, of whom 566 were eligible and consented or had consent provided to participate. Of these 566 patients, 184 were assigned to the placebo group, 192 to the haloperidol group, and 190 to the ziprasidone group. 1-year survival and follow-up rates were similar between groups. Cognitive impairment was common in all three treatment groups, with a third of survivors impaired at both 3-month and 12-month follow-up in all groups. More than half of the surveyed survivors in each group had cognitive or physical limitations (or both) that precluded employment at both 3-month and 12-month follow-up. At both 3 months and 12 months, neither haloperidol (adjusted odds ratio 1·22 [95% CI 0·73-2.04] at 3 months and 1·12 [0·60-2·11] at 12 months) nor ziprasidone (1·07 [0·59-1·96] at 3 months and 0·94 [0·62-1·44] at 12 months) significantly altered cognitive outcomes, as measured by the Telephone Interview for Cognitive Status T score, compared with placebo. We also found no evidence that functional, psychological, quality-of-life, or employment outcomes improved with haloperidol or ziprasidone compared with placebo. INTERPRETATION: In delirious, critically ill patients, neither haloperidol nor ziprasidone had a significant effect on cognitive, functional, psychological, or quality-of-life outcomes among survivors. Our findings, along with insufficient evidence of short-term benefit and frequent inappropriate continuation of antipsychotics at hospital discharge, indicate that antipsychotics should not be used routinely to treat delirium in critically ill adults. FUNDING: National Institutes of Health and the US Department of Veterans Affairs.


Asunto(s)
Antipsicóticos , Enfermedad Crítica , Delirio , Calidad de Vida , Humanos , Antipsicóticos/uso terapéutico , Antipsicóticos/efectos adversos , Delirio/tratamiento farmacológico , Masculino , Enfermedad Crítica/psicología , Enfermedad Crítica/terapia , Femenino , Persona de Mediana Edad , Método Doble Ciego , Anciano , Haloperidol/uso terapéutico , Resultado del Tratamiento , Piperazinas/uso terapéutico , Piperazinas/efectos adversos , Adulto , Tiazoles/uso terapéutico , Tiazoles/efectos adversos , Tiazoles/administración & dosificación , Estudios de Seguimiento , Unidades de Cuidados Intensivos
2.
Ground Water ; 61(3): 330-345, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36116941

RESUMEN

Changes in climate and land use will alter groundwater heat transport dynamics in the future. These changes will in turn affect watershed processes (e.g., nutrient cycling) as well as watershed characteristics (e.g., distribution and persistence of cold-water habitat). Thus, groundwater flow and heat transport models at watershed scales that can characterize and quantify thermal impacts of surface temperature change on groundwater system temperatures may support forecasting changes to groundwater-linked ecosystems in riparian zones, streams, and lakes. Including unsaturated zone processes has previously been shown to be important for properly determining the timing and magnitude of groundwater recharge (Hunt et al. 2008). Similarly, heat transport dynamics in the saturated-zone, as well as connected surface-water systems, can be appreciably influenced by unsaturated-zone processes; in this way the unsaturated zone forms an inextricable link between the land surface where change occurs and the groundwater system that transmits that change. This paper presents new capabilities for the existing MT3D-USGS transport simulator by adding functionality for simulating heat transport through the unsaturated zone. New simulation capabilities are verified through comparison of simulation results with those of the variably saturated heat transport simulator VS2DH under steady and transient conditions for both water and heat flow. The new capabilities are assessed using a number of conceptualizations and include evaluations of convective and conductive heat flow. These additional capabilities increase the utility for applied watershed-scale simulations, which in turn may facilitate more realistic characterizations of temperature change on thermally sensitive ecosystems, such as stream habitat.


Asunto(s)
Agua Subterránea , Calor , Ecosistema , Clima , Agua
3.
Ground Water ; 58(4): 524-534, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-31364162

RESUMEN

Protection of fens-wetlands dependent on groundwater discharge-requires characterization of groundwater sources and stresses. Because instrumentation and numerical modeling of fens is labor intensive, easy-to-apply methods that model fen distribution and their vulnerability to development are desirable. Here we demonstrate that fen areas can be simulated using existing steady-state MODFLOW models when the unsaturated zone flow (UZF) package is included. In cells where the water table is near land surface, the UZF package calculates a head difference and scaled conductance at these "seepage drain" cells to generate average rates of vertical seepage to the land. This formulation, which represents an alternative to blanketing the MODFLOW domain with drains, requires very little input from the user because unsaturated flow-routing is inactive and results are primarily driven by easily obtained topographic information. Like the drain approach, it has the advantage that the distribution of seepage areas is not predetermined by the modeler, but rather emerges from simulated heads. Beyond the drain approach, it takes account of intracell land surface variation to explicitly quantify multiple surficial flows corresponding to infiltration, rejected recharge, recharge and land-surface seepage. Application of the method to a basin in southeastern Wisconsin demonstrates how it can be used as a decision-support tool to first, reproduce fen distribution and, second, forecast drawdown and reduced seepage at fens in response to shallow pumping.


Asunto(s)
Agua Subterránea , Predicción , Modelos Teóricos , Movimientos del Agua , Humedales , Wisconsin
4.
N Engl J Med ; 379(26): 2506-2516, 2018 12 27.
Artículo en Inglés | MEDLINE | ID: mdl-30346242

RESUMEN

BACKGROUND: There are conflicting data on the effects of antipsychotic medications on delirium in patients in the intensive care unit (ICU). METHODS: In a randomized, double-blind, placebo-controlled trial, we assigned patients with acute respiratory failure or shock and hypoactive or hyperactive delirium to receive intravenous boluses of haloperidol (maximum dose, 20 mg daily), ziprasidone (maximum dose, 40 mg daily), or placebo. The volume and dose of a trial drug or placebo was halved or doubled at 12-hour intervals on the basis of the presence or absence of delirium, as detected with the use of the Confusion Assessment Method for the ICU, and of side effects of the intervention. The primary end point was the number of days alive without delirium or coma during the 14-day intervention period. Secondary end points included 30-day and 90-day survival, time to freedom from mechanical ventilation, and time to ICU and hospital discharge. Safety end points included extrapyramidal symptoms and excessive sedation. RESULTS: Written informed consent was obtained from 1183 patients or their authorized representatives. Delirium developed in 566 patients (48%), of whom 89% had hypoactive delirium and 11% had hyperactive delirium. Of the 566 patients, 184 were randomly assigned to receive placebo, 192 to receive haloperidol, and 190 to receive ziprasidone. The median duration of exposure to a trial drug or placebo was 4 days (interquartile range, 3 to 7). The median number of days alive without delirium or coma was 8.5 (95% confidence interval [CI], 5.6 to 9.9) in the placebo group, 7.9 (95% CI, 4.4 to 9.6) in the haloperidol group, and 8.7 (95% CI, 5.9 to 10.0) in the ziprasidone group (P=0.26 for overall effect across trial groups). The use of haloperidol or ziprasidone, as compared with placebo, had no significant effect on the primary end point (odds ratios, 0.88 [95% CI, 0.64 to 1.21] and 1.04 [95% CI, 0.73 to 1.48], respectively). There were no significant between-group differences with respect to the secondary end points or the frequency of extrapyramidal symptoms. CONCLUSIONS: The use of haloperidol or ziprasidone, as compared with placebo, in patients with acute respiratory failure or shock and hypoactive or hyperactive delirium in the ICU did not significantly alter the duration of delirium. (Funded by the National Institutes of Health and the VA Geriatric Research Education and Clinical Center; MIND-USA ClinicalTrials.gov number, NCT01211522 .).


Asunto(s)
Antipsicóticos/uso terapéutico , Enfermedad Crítica/psicología , Delirio/tratamiento farmacológico , Antagonistas de Dopamina/uso terapéutico , Haloperidol/uso terapéutico , Piperazinas/uso terapéutico , Tiazoles/uso terapéutico , Anciano , Antipsicóticos/efectos adversos , Enfermedad Crítica/mortalidad , Enfermedad Crítica/terapia , Método Doble Ciego , Femenino , Haloperidol/administración & dosificación , Haloperidol/efectos adversos , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Piperazinas/administración & dosificación , Piperazinas/efectos adversos , Insuficiencia Respiratoria/psicología , Choque/psicología , Tiazoles/administración & dosificación , Tiazoles/efectos adversos , Insuficiencia del Tratamiento
5.
Ground Water ; 54(4): 532-44, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-26757094

RESUMEN

In order to better represent the configuration of the stream network and simulate local groundwater-surface water interactions, a version of MODFLOW with refined spacing in the topmost layer was applied to a Lake Michigan Basin (LMB) regional groundwater-flow model developed by the U.S. Geological. Regional MODFLOW models commonly use coarse grids over large areas; this coarse spacing precludes model application to local management issues (e.g., surface-water depletion by wells) without recourse to labor-intensive inset models. Implementation of an unstructured formulation within the MODFLOW framework (MODFLOW-USG) allows application of regional models to address local problems. A "semi-structured" approach (uniform lateral spacing within layers, different lateral spacing among layers) was tested using the LMB regional model. The parent 20-layer model with uniform 5000-foot (1524-m) lateral spacing was converted to 4 layers with 500-foot (152-m) spacing in the top glacial (Quaternary) layer, where surface water features are located, overlying coarser resolution layers representing deeper deposits. This semi-structured version of the LMB model reproduces regional flow conditions, whereas the finer resolution in the top layer improves the accuracy of the simulated response of surface water to shallow wells. One application of the semi-structured LMB model is to provide statistical measures of the correlation between modeled inputs and the simulated amount of water that wells derive from local surface water. The relations identified in this paper serve as the basis for metamodels to predict (with uncertainty) surface-water depletion in response to shallow pumping within and potentially beyond the modeled area, see Fienen et al. (2015a).


Asunto(s)
Agua Subterránea , Movimientos del Agua , Modelos Teóricos , Agua , Pozos de Agua
8.
Crit Care Nurs Q ; 37(2): 170-81, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24595254

RESUMEN

The purpose of this study was to determine whether the addition of rapid-acting insulin bolus for enteral feed coverage and a reduction in basal insulin improve glycemic control and decrease hypoglycemia in a medical intensive care unit. A quasi-experimental posttest design assessing glucose control postimplementation of a revised nurse-driven ICU hyperglycemia protocol was conducted on a 16-bed medical intensive care unit at a multicenter hospital system. A daily report of all patients on the ICU hyperglycemia protocol was automated for the inpatient diabetes management team, and pertinent data were collected. Univariate statistics were conducted for all variables. The variability in blood glucose based on different clinical variables was compared using t tests. The hypoglycemic rate was only 0.72%, and no glucose value was less than 40 mg/dL. In addition, the mean glucose value throughout the study was 160.9 ± 35.6 mg/dL. Findings from this study will hopefully provide insight on an effective way to control glucose within a medical intensive care unit as well as reduce hypoglycemia rates within this setting.


Asunto(s)
Enfermería de Cuidados Críticos/métodos , Diabetes Mellitus/tratamiento farmacológico , Hiperglucemia/enfermería , Hiperglucemia/prevención & control , Insulina/administración & dosificación , Unidades de Cuidados Intensivos , Adulto , Anciano , Anciano de 80 o más Años , Análisis de Varianza , Glucemia/análisis , Cuidados Críticos/métodos , Diabetes Mellitus/sangre , Diabetes Mellitus/enfermería , Femenino , Estudios de Seguimiento , Índice Glucémico , Humanos , Hiperglucemia/tratamiento farmacológico , Infusiones Intravenosas , Masculino , Persona de Mediana Edad , Proyectos Piloto , Medición de Riesgo , Índice de Severidad de la Enfermedad , Resultado del Tratamiento , Adulto Joven
9.
Crit Care ; 17(2): R72, 2013 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-23594407

RESUMEN

INTRODUCTION: Data are sparse as to whether obesity influences the risk of death in critically ill patients with septic shock. We sought to examine the possible impact of obesity, as assessed by body mass index (BMI), on hospital mortality in septic shock patients. METHODS: We performed a nested cohort study within a retrospective database of patients with septic shock conducted in 28 medical centers in Canada, United States and Saudi Arabia between 1996 and 2008. Patients were classified according to the World Health Organization criteria for BMI. Multivariate logistic regression analysis was performed to evaluate the association between obesity and hospital mortality. RESULTS: Of the 8,670 patients with septic shock, 2,882 (33.2%) had height and weight data recorded at ICU admission and constituted the study group. Obese patients were more likely to have skin and soft tissue infections and less likely to have pneumonia with predominantly Gram-positive microorganisms. Crystalloid and colloid resuscitation fluids in the first six hours were given at significantly lower volumes per kg in the obese and very obese patients compared to underweight and normal weight patients (for crystalloids: 55.0 ± 40.1 ml/kg for underweight, 43.2 ± 33.4 for normal BMI, 37.1 ± 30.8 for obese and 27.7 ± 22.0 for very obese). Antimicrobial doses per kg were also different among BMI groups. Crude analysis showed that obese and very obese patients had lower hospital mortality compared to normal weight patients (odds ratio (OR) 0.80, 95% confidence interval (CI) 0.66 to 0.97 for obese and OR 0.61, 95% CI 0.44 to 0.85 for very obese patients). After adjusting for baseline characteristics and sepsis interventions, the association became non-significant (OR 0.80, 95% CI 0.62 to 1.02 for obese and OR 0.69, 95% CI 0.45 to 1.04 for very obese). CONCLUSIONS: The obesity paradox (lower mortality in the obese) documented in other populations is also observed in septic shock. This may be related in part to differences in patient characteristics. However, the true paradox may lie in the variations in the sepsis interventions, such as the administration of resuscitation fluids and antimicrobial therapy. Considering the obesity epidemic and its impact on critical care, further studies are warranted to examine whether a weight-based approach to common therapeutic interventions in septic shock influences outcome.


Asunto(s)
Índice de Masa Corporal , Internacionalidad , Obesidad/epidemiología , Obesidad/terapia , Choque Séptico/epidemiología , Choque Séptico/terapia , Adulto , Anciano , Estudios de Cohortes , Femenino , Mortalidad Hospitalaria/tendencias , Humanos , Masculino , Persona de Mediana Edad , Obesidad/diagnóstico , Estudios Retrospectivos , Choque Séptico/diagnóstico , Resultado del Tratamiento
10.
Hepatology ; 56(6): 2305-15, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22753144

RESUMEN

UNLABELLED: It is unclear whether practice-related aspects of antimicrobial therapy contribute to the high mortality from septic shock among patients with cirrhosis. We examined the relationship between aspects of initial empiric antimicrobial therapy and mortality in patients with cirrhosis and septic shock. This was a nested cohort study within a large retrospective database of septic shock from 28 medical centers in Canada, the United States, and Saudi Arabia by the Cooperative Antimicrobial Therapy of Septic Shock Database Research Group between 1996 and 2008. We examined the impact of initial empiric antimicrobial therapeutic variables on the hospital mortality of patients with cirrhosis and septic shock. Among 635 patients with cirrhosis and septic shock, the hospital mortality was 75.6%. Inappropriate initial empiric antimicrobial therapy was administered in 155 (24.4%) patients. The median time to appropriate antimicrobial administration was 7.3 hours (interquartile range, 3.2-18.3 hours). The use of inappropriate initial antimicrobials was associated with increased mortality (adjusted odds ratio [aOR], 9.5; 95% confidence interval [CI], 4.3-20.7], as was the delay in appropriate antimicrobials (aOR for each 1 hour increase, 1.1; 95% CI, 1.1-1.2). Among patients with eligible bacterial septic shock, a single rather than two or more appropriate antimicrobials was used in 226 (72.9%) patients and was also associated with higher mortality (aOR, 1.8; 95% CI, 1.0-3.3). These findings were consistent across various clinically relevant subgroups. CONCLUSION: In patients with cirrhosis and septic shock, inappropriate and delayed appropriate initial empiric antimicrobial therapy is associated with increased mortality. Monotherapy of bacterial septic shock is also associated with increased mortality. The process of selection and implementation of empiric antimicrobial therapy in this high-risk group should be restructured.


Asunto(s)
Antiinfecciosos/uso terapéutico , Mortalidad Hospitalaria , Cirrosis Hepática/complicaciones , Errores de Medicación , Choque Séptico/tratamiento farmacológico , APACHE , Adulto , Anciano , Antiinfecciosos/administración & dosificación , Infecciones Bacterianas/tratamiento farmacológico , Canadá , Intervalos de Confianza , Cuidados Críticos , Quimioterapia Combinada , Femenino , Humanos , Tiempo de Internación , Modelos Lineales , Modelos Logísticos , Masculino , Persona de Mediana Edad , Micosis/tratamiento farmacológico , Oportunidad Relativa , Estudios Retrospectivos , Arabia Saudita , Índice de Severidad de la Enfermedad , Choque Séptico/complicaciones , Choque Séptico/microbiología , Estadísticas no Paramétricas , Factores de Tiempo , Estados Unidos
11.
Crit Care Med ; 38(9): 1773-85, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20639750

RESUMEN

BACKGROUND: Septic shock represents the major cause of infection-associated mortality in the intensive care unit. The possibility that combination antibiotic therapy of bacterial septic shock improves outcome is controversial. Current guidelines do not recommend combination therapy except for the express purpose of broadening coverage when resistant pathogens are a concern. OBJECTIVE: To evaluate the therapeutic benefit of early combination therapy comprising at least two antibiotics of different mechanisms with in vitro activity for the isolated pathogen in patients with bacterial septic shock. DESIGN: Retrospective, propensity matched, multicenter, cohort study. SETTING: Intensive care units of 28 academic and community hospitals in three countries between 1996 and 2007. SUBJECTS: A total of 4662 eligible cases of culture-positive, bacterial septic shock treated with combination or monotherapy from which 1223 propensity-matched pairs were generated. MEASUREMENTS AND MAIN RESULTS: The primary outcome of study was 28-day mortality. Using a Cox proportional hazards model, combination therapy was associated with decreased 28-day mortality (444 of 1223 [36.3%] vs. 355 of 1223 [29.0%]; hazard ratio, 0.77; 95% confidence interval, 0.67-0.88; p = .0002). The beneficial impact of combination therapy applied to both Gram-positive and Gram-negative infections but was restricted to patients treated with beta-lactams in combination with aminoglycosides, fluoroquinolones, or macrolides/clindamycin. Combination therapy was also associated with significant reductions in intensive care unit (437 of 1223 [35.7%] vs. 352 of 1223 [28.8%]; odds ratio, 0.75; 95% confidence interval, 0.63-0.92; p = .0006) and hospital mortality (584 of 1223 [47.8%] vs. 457 of 1223 [37.4%]; odds ratio, 0.69; 95% confidence interval, 0.59-0.81; p < .0001). The use of combination therapy was associated with increased ventilator (median and [interquartile range], 10 [0-25] vs. 17 [0-26]; p = .008) and pressor/inotrope-free days (median and [interquartile range], 23 [0-28] vs. 25 [0-28]; p = .007) up to 30 days. CONCLUSION: Early combination antibiotic therapy is associated with decreased mortality in septic shock. Prospective randomized trials are needed.


Asunto(s)
Antibacterianos/uso terapéutico , Choque Séptico/tratamiento farmacológico , Tasa de Supervivencia , Anciano , Antibacterianos/administración & dosificación , Quimioterapia Combinada , Femenino , Humanos , Masculino , Persona de Mediana Edad , Puntaje de Propensión , Estudios Retrospectivos , Choque Séptico/microbiología , Resultado del Tratamiento
12.
Crit Care Med ; 34(6): 1589-96, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16625125

RESUMEN

OBJECTIVE: To determine the prevalence and impact on mortality of delays in initiation of effective antimicrobial therapy from initial onset of recurrent/persistent hypotension of septic shock. DESIGN: A retrospective cohort study performed between July 1989 and June 2004. SETTING: Fourteen intensive care units (four medical, four surgical, six mixed medical/surgical) and ten hospitals (four academic, six community) in Canada and the United States. PATIENTS: Medical records of 2,731 adult patients with septic shock. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The main outcome measure was survival to hospital discharge. Among the 2,154 septic shock patients (78.9% total) who received effective antimicrobial therapy only after the onset of recurrent or persistent hypotension, a strong relationship between the delay in effective antimicrobial initiation and in-hospital mortality was noted (adjusted odds ratio 1.119 [per hour delay], 95% confidence interval 1.103-1.136, p<.0001). Administration of an antimicrobial effective for isolated or suspected pathogens within the first hour of documented hypotension was associated with a survival rate of 79.9%. Each hour of delay in antimicrobial administration over the ensuing 6 hrs was associated with an average decrease in survival of 7.6%. By the second hour after onset of persistent/recurrent hypotension, in-hospital mortality rate was significantly increased relative to receiving therapy within the first hour (odds ratio 1.67; 95% confidence interval, 1.12-2.48). In multivariate analysis (including Acute Physiology and Chronic Health Evaluation II score and therapeutic variables), time to initiation of effective antimicrobial therapy was the single strongest predictor of outcome. Median time to effective antimicrobial therapy was 6 hrs (25-75th percentile, 2.0-15.0 hrs). CONCLUSIONS: Effective antimicrobial administration within the first hour of documented hypotension was associated with increased survival to hospital discharge in adult patients with septic shock. Despite a progressive increase in mortality rate with increasing delays, only 50% of septic shock patients received effective antimicrobial therapy within 6 hrs of documented hypotension.


Asunto(s)
Antiinfecciosos/uso terapéutico , Hipotensión/epidemiología , Choque Séptico/mortalidad , Adulto , Femenino , Estudios de Seguimiento , Mortalidad Hospitalaria/tendencias , Humanos , Hipotensión/etiología , Masculino , Manitoba/epidemiología , Persona de Mediana Edad , Oportunidad Relativa , Alta del Paciente/estadística & datos numéricos , Alta del Paciente/tendencias , Prevalencia , Estudios Retrospectivos , Choque Séptico/complicaciones , Choque Séptico/tratamiento farmacológico , Tasa de Supervivencia/tendencias , Factores de Tiempo , Estados Unidos/epidemiología
13.
Ground Water ; 44(2): 201-11, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-16556202

RESUMEN

Aquitards protect underlying aquifers from contaminants and limit recharge to those aquifers. Understanding the mechanisms and quantity of ground water flow across aquitards to underlying aquifers is essential for ground water planning and assessment. We present results of laboratory testing for shale hydraulic conductivities, a methodology for determining the vertical hydraulic conductivity (K(v)) of aquitards at regional scales and demonstrate the importance of discrete flow pathways across aquitards. A regional shale aquitard in southeastern Wisconsin, the Maquoketa Formation, was studied to define the role that an aquitard plays in a regional ground water flow system. Calibration of a regional ground water flow model for southeastern Wisconsin using both predevelopment steady-state and transient targets suggested that the regional K(v) of the Maquoketa Formation is 1.8 x 10(-11) m/s. The core-scale measurements of the K(v) of the Maquoketa Formation range from 1.8 x 10(-14) to 4.1 x 10(-12) m/s. Flow through some additional pathways in the shale, potential fractures or open boreholes, can explain the apparent increase of the regional-scale K(v). Based on well logs, erosional windows or high-conductivity zones seem unlikely pathways. Fractures cutting through the entire thickness of the shale spaced 5 km apart with an aperture of 50 microns could provide enough flow across the aquitard to match that provided by an equivalent bulk K(v) of 1.8 x 10(-11) m/s. In a similar fashion, only 50 wells of 0.1 m radius open to aquifers above and below the shale and evenly spaced 10 km apart across southeastern Wisconsin can match the model K(v).


Asunto(s)
Movimientos del Agua , Abastecimiento de Agua , Fenómenos Geológicos , Geología , Wisconsin
14.
Ground Water ; 41(2): 190-9, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12656285

RESUMEN

A stepwise modeling approach is implemented in which a regional one-layer analytic element model is used to simulate the flow system and to furnish boundary conditions for an extracted local three-dimensional model. In this case study the stepwise approach is used to evaluate the fate of recharge in the Menomonee Valley adjacent to Lake Michigan. Two major receptors exist for recharge that flows through contaminated valley fill: the surface water estuary and a tunnel system constructed approximately 75 to 110 m below land surface to store storm runoff. The primary objective of the modeling is to delineate the contributing areas of recharge to each receptor. Of interest is the ability of the one-layer regional model to furnish flux boundary conditions to the local three-dimensional model despite the presence of vertical flow conditions at the boundaries of the local model. Sensitivity analysis suggests that the local model was insensitive to the vertical distribution of the flux. Each step of the modeling approach demonstrates that both receptors play an important role in capturing valley recharge. The pattern of capture of the one-layer model differed in shape from that delineated by the multi-layer local model in the presence of a flow system with pronounced vertical anisotropy and with sinks drawing water from different elevations.


Asunto(s)
Modelos Teóricos , Movimientos del Agua , Abastecimiento de Agua , Predicción
15.
Ground Water ; 41(2): 227-37, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12656289

RESUMEN

Approaches for modeling lake-ground water interactions have evolved significantly from early simulations that used fixed lake stages specified as constant head to sophisticated LAK packages for MODFLOW. Although model input can be complex, the LAK package capabilities and output are superior to methods that rely on a fixed lake stage and compare well to other simple methods where lake stage can be calculated. Regardless of the approach, guidelines presented here for model grid size, location of three-dimensional flow, and extent of vertical capture can facilitate the construction of appropriately detailed models that simulate important lake-ground water interactions without adding unnecessary complexity. In addition to MODFLOW approaches, lake simulation has been formulated in terms of analytic elements. The analytic element lake package had acceptable agreement with a published LAKI problem, even though there were differences in the total lake conductance and number of layers used in the two models. The grid size used in the original LAKI problem, however, violated a grid size guideline presented in this paper. Grid sensitivity analyses demonstrated that an appreciable discrepancy in the distribution of stream and lake flux was related to the large grid size used in the original LAKI problem. This artifact is expected regardless of MODFLOW LAK package used. When the grid size was reduced, a finite-difference formulation approached the analytic element results. These insights and guidelines can help ensure that the proper lake simulation tool is being selected and applied.


Asunto(s)
Modelos Teóricos , Movimientos del Agua , Abastecimiento de Agua , Guías como Asunto , Reproducibilidad de los Resultados , Suelo
16.
Expert Opin Investig Drugs ; 11(12): 1795-812, 2002 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-12457439

RESUMEN

Severe sepsis and septic shock is a common problem encountered in the critical care unit with an estimated incidence in the US of 750,000 cases/year and a mortality rate of 30-50%. Sepsis involves a complex interaction between bacterial factors and the host immune system producing a systemic inflammatory state that may progress to multiple organ failure and death. Endotoxin (a lipopolysaccharide) released from Gram-negative bacteria has been implicated as a potent, prototypical stimulus of the immune response to bacterial infection. Current antiendotoxin strategies utilise various approaches ranging from the prevention of binding to endotoxin receptors with antibodies (monoclonal or polyclonal) against endotoxin or endotoxin receptor/carrier molecules (antiCD14 or antilipopolysaccharide-binding protein antibodies), enhancing clearance or neutralisation (haemoperfusion, lipoproteins, lipopolysaccharide-neutralising proteins) or impairing cellular signalling (lipid A analogues, tyrosine kinase inhibitors). In the future, innovative therapies involving Toll-like receptors and their downstream signalling elements will be developed. This review discusses current knowledge regarding endotoxin signalling, antiendotoxin therapies currently under development, and future areas for research.


Asunto(s)
Proteínas de Fase Aguda , Endotoxinas/antagonistas & inhibidores , Glicoproteínas de Membrana , Sepsis/tratamiento farmacológico , Taurina/análogos & derivados , Anticuerpos Monoclonales/uso terapéutico , Proteínas Portadoras/antagonistas & inhibidores , Humanos , Receptores de Lipopolisacáridos/efectos de los fármacos , Polimixina B/uso terapéutico , Transducción de Señal/efectos de los fármacos , Taurina/uso terapéutico , Tiadiazinas/uso terapéutico , Vacunación
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