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1.
Semin Neurol ; 44(2): 178-192, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38485124

RESUMEN

The burden of neurological disease is increasing globally. In the United States, this burden is disproportionally greater for Black and Latino communities who have limited access to neurological care. Health services researchers have attempted to identify racial and ethnic disparities in neurological care and possible solutions. This article reviews the most current literature on racial and ethnic disparities in commonly encountered neurological conditions, including Stroke, Alzheimer's Disease, Multiple Sclerosis, Epilepsy, Parkinson's Disease, and Migraine. Disparities exist in disease incidence, diagnosis, access to care, treatment, outcomes, and representation in epidemiologic studies and clinical trials. Many of the disparities observed in neurological care in the United States are a consequence of longstanding racist and discriminatory policies and legislation that increase risk factors for the development of neurological disease or lead to disparities in accessing quality neurological care. Therefore, additional efforts on the legislative, community health, and healthcare system levels are necessary to prevent the onset of neurological disease and achieve equity in neurological care.


Asunto(s)
Accesibilidad a los Servicios de Salud , Disparidades en Atención de Salud , Neurología , Grupos Raciales , Humanos , Estados Unidos
2.
Ann Intern Med ; 175(2): 179-190, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34781715

RESUMEN

BACKGROUND: Although most patients with SARS-CoV-2 infection can be safely managed at home, the need for hospitalization can arise suddenly. OBJECTIVE: To determine whether enrollment in an automated remote monitoring service for community-dwelling adults with COVID-19 at home ("COVID Watch") was associated with improved mortality. DESIGN: Retrospective cohort analysis. SETTING: Mid-Atlantic academic health system in the United States. PARTICIPANTS: Outpatients who tested positive for SARS-CoV-2 between 23 March and 30 November 2020. INTERVENTION: The COVID Watch service consists of twice-daily, automated text message check-ins with an option to report worsening symptoms at any time. All escalations were managed 24 hours a day, 7 days a week by dedicated telemedicine clinicians. MEASUREMENTS: Thirty- and 60-day outcomes of patients enrolled in COVID Watch were compared with those of patients who were eligible to enroll but received usual care. The primary outcome was death at 30 days. Secondary outcomes included emergency department (ED) visits and hospitalizations. Treatment effects were estimated with propensity score-weighted risk adjustment models. RESULTS: A total of 3488 patients enrolled in COVID Watch and 4377 usual care control participants were compared with propensity score weighted models. At 30 days, COVID Watch patients had an odds ratio for death of 0.32 (95% CI, 0.12 to 0.72), with 1.8 fewer deaths per 1000 patients (CI, 0.5 to 3.1) (P = 0.005); at 60 days, the difference was 2.5 fewer deaths per 1000 patients (CI, 0.9 to 4.0) (P = 0.002). Patients in COVID Watch had more telemedicine encounters, ED visits, and hospitalizations and presented to the ED sooner (mean, 1.9 days sooner [CI, 0.9 to 2.9 days]; all P < 0.001). LIMITATION: Observational study with the potential for unobserved confounding. CONCLUSION: Enrollment of outpatients with COVID-19 in an automated remote monitoring service was associated with reduced mortality, potentially explained by more frequent telemedicine encounters and more frequent and earlier presentation to the ED. PRIMARY FUNDING SOURCE: Patient-Centered Outcomes Research Institute.


Asunto(s)
COVID-19/terapia , Consulta Remota/métodos , Envío de Mensajes de Texto , Adulto , Anciano , COVID-19/mortalidad , Investigación sobre la Eficacia Comparativa , Servicio de Urgencia en Hospital , Femenino , Servicios de Atención de Salud a Domicilio , Hospitalización , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Estados Unidos/epidemiología
3.
BMC Med Educ ; 23(1): 960, 2023 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-38098006

RESUMEN

BACKGROUND: Medical school acceptance rates in the United States (US) have been lower for applicants who identify as Underrepresented-in-Medicine (UiM) compared to non-UiM applicants. The gap between UiM and no-UiM groups is narrowing in recent years. Less well-studied are associations of acceptance decisions with family income and parental education. This study's purpose is to evaluate the relationships between medical school acceptance and family income, parental education status, racial/ethnic background, Grade Point Average (GPA), Medical College Admission Test (MCAT) score, and participation in extracurricular activities. METHODS: This is a cross-sectional study of first-time US medical school applicants between 2017 and 2020. Acceptance rates for first-time applicants were calculated for first-generation (FG), low-income (LI), and UiM applicants. Associations of these attributes with MCAT scores, science GPAs, and seven categories of extracurricular activities were evaluated. Regression analyses estimated associations between acceptance to medical school with all variables with and without interaction terms (FG*URM, LI*URM, FG*LI). RESULTS: The overall acceptance rate for first-time applicants from 2017-2020 was 45.3%. The acceptance rates among FG, LI and UiM applicants were 37.9%, 39.6% and 44.2%, respectively. In univariable logistic regression analyses, acceptance was negatively associated with being FG (OR: 0.68, CI: 0.67-0.70), LI (OR: 0.70, CI: 0.69-0.72), and UiM (OR: 0.95, CI: 0.93-0.97). In multivariable regression, acceptance was most strongly associated with science GPA (OR: 7.15, CI: 6.78-7.54 for the highest quintile) and UiM (OR: 5.56, CI: 5.48-5.93) status and MCAT score (OR: 1.19, CI: 1.18-1.19), FG (OR: 1.14, CI: 1.10-1.18), and most extracurricular activities. Including interaction terms revealed a negative association between acceptance and LI (OR:0.90, CI: 0.87-0.94) and FG was no longer significant (OR:1.10, CI:0.96-1.08). CONCLUSIONS: Collectively these results suggest medical school admissions committees may be relying on holistic admission practices. While MCAT and GPA scores continue to predict acceptance, individuals from racially and ethnically UiM backgrounds have favorable odds of acceptance when controlling for MCAT and GPA. However, these positive associations were not seen for low-income and first-generation applicants. Additional preparation for college and the MCAT for these latter groups may help further diversify the medical profession.


Asunto(s)
Criterios de Admisión Escolar , Facultades de Medicina , Humanos , Estados Unidos , Estudios Transversales , Etnicidad , Prueba de Admisión Académica
4.
Aesthet Surg J ; 42(2): 133-148, 2022 01 12.
Artículo en Inglés | MEDLINE | ID: mdl-33855336

RESUMEN

BACKGROUND: Facial features and measurements are utilized to analyze patients' faces for various reasons, including surgical planning, scientific communications, patient-surgeon communications, and post-surgery evaluations. OBJECTIVES: There are numerous descriptions regarding these features and measurements scattered throughout the literature, and the authors did not encounter a current compilation of these parameters in the medical literature. METHODS: A narrative literature review of the published medical literature for facial measurements used for facial analysis in rhinoplasty was conducted through the electronic databases MEDLINE/PubMed and Google Scholar, along with a citation search. RESULTS: A total of 61 facial features were identified: 45 points (25 bilateral, 20 unilateral), 5 lines (3 bilateral, 2 unilateral), 8 planes, and 3 areas.A total of 122 measurements were identified: 48 distances (6 bilateral, 42 unilateral), 57 angles (13 bilateral, 44 unilateral), and 17 ratios. Supplemental figures were created to depict all features and measurements utilizing a frontal, lateral, or basal view of the face. CONCLUSIONS: This paper provides the most comprehensive and current compilation of facial measurements to date. The authors believe this compilation will guide further developments (methodologies and software tools) for analyzing nasal structures and assessing the objective outcomes of facial surgeries, in particular rhinoplasty. Moreover, it will improve communication as a reference for facial measurements of facial surface anthropometry, in particular rhinoplasty.


Asunto(s)
Rinoplastia , Cirujanos , Antropometría , Humanos , Nariz/anatomía & histología , Nariz/cirugía , Programas Informáticos
5.
Sensors (Basel) ; 21(8)2021 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-33920610

RESUMEN

Construction activities typically create large amounts of ground disturbance, which can lead to increased rates of soil erosion. Construction stormwater practices are used on active jobsites to protect downstream waterbodies from offsite sediment transport. Federal and state regulations require routine pollution prevention inspections to ensure that temporary stormwater practices are in place and performing as intended. This study addresses the existing challenges and limitations in the construction stormwater inspections and presents a unique approach for performing unmanned aerial system (UAS)-based inspections. Deep learning-based object detection principles were applied to identify and locate practices installed on active construction sites. The system integrates a post-processing stage by clustering results. The developed framework consists of data preparation with aerial inspections, model training, validation of the model, and testing for accuracy. The developed model was created from 800 aerial images and was used to detect four different types of construction stormwater practices at 100% accuracy on the Mean Average Precision (MAP) with minimal false positive detections. Results indicate that object detection could be implemented on UAS-acquired imagery as a novel approach to construction stormwater inspections and provide accurate results for site plan comparisons by rapidly detecting the quantity and location of field-installed stormwater practices.

6.
Cardiol Young ; 28(1): 118-125, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28847337

RESUMEN

OBJECTIVE: To evaluate differences in interstage growth of pulmonary arteries between use of polytetrafluoroethylene and femoral vein homograft as Sano shunt during stage-I Norwood palliation. METHODS: A retrospective review of all patients who survived to the second stage following Norwood-Sano operation at two institutions was performed. Either polytetrafluoroethylene or the valved segment of femoral vein homograft was used for construction of the Sano shunt. The size of pulmonary arteries was compared at pre-Glenn catheterisation. RESULTS: A total of 48 neonates with the diagnosis of hypoplastic left heart syndrome or its variants comprised the study population. Femoral vein homograft of 5-6 mm diameter was used in 14 and polytetrafluoroethylene graft of 5 mm was used in 34 patients. The two groups were comparable in terms of preoperative demographics and age at time of pre-Glenn catheterisation (3.9±0.7 versus 3.4±0.8 months, p=0.06). Patients who received femoral vein homograft demonstrated a significantly higher pre-Glenn Nakata index [264 (130-460) versus 165 (108-234) mm2/m2, p=0.004]. The individual branch pulmonary arteries were significantly larger in the femoral vein group (right, 7.8±3.6 versus 5.0±1.2, p=0.014; left, 7.2±2.1 versus 5.6±1.9, p=0.02). There were no differences in cardiac index, Qp:Qs, ventricular end-diastolic pressure or systemic oxygen saturations. CONCLUSIONS: Utilisation of a valved segment of femoral vein homograft as right ventricle to pulmonary artery conduit during Norwood-Sano operation confers better interstage growth of the pulmonary arteries. Further studies are needed to evaluate the impact of femoral vein homograft on single ventricle function.


Asunto(s)
Prótesis Vascular , Vena Femoral/trasplante , Síndrome del Corazón Izquierdo Hipoplásico/cirugía , Procedimientos de Norwood , Arteria Pulmonar/cirugía , Femenino , Ventrículos Cardíacos/fisiopatología , Humanos , Recién Nacido , Masculino , Politetrafluoroetileno , Prótesis e Implantes , Estudios Retrospectivos , Trasplante Homólogo , Presión Ventricular
7.
Nucleic Acids Res ; 43(9): e62, 2015 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-25820427

RESUMEN

Mutations in human mitochondrial DNA (mtDNA) can cause mitochondrial disease and have been associated with neurodegenerative disorders, cancer, diabetes and aging. Yet our progress toward delineating the precise contributions of mtDNA mutations to these conditions is impeded by the limited availability of faithful transmitochondrial animal models. Here, we report a method for the isolation of mutations in mouse mtDNA and its implementation for the generation of a collection of over 150 cell lines suitable for the production of transmitochondrial mice. This method is based on the limited mutagenesis of mtDNA by proofreading-deficient DNA-polymerase γ followed by segregation of the resulting highly heteroplasmic mtDNA population by means of intracellular cloning. Among generated cell lines, we identify nine which carry mutations affecting the same amino acid or nucleotide positions as in human disease, including a mutation in the ND4 gene responsible for 70% of Leber Hereditary Optic Neuropathies (LHON). Similar to their human counterparts, cybrids carrying the homoplasmic mouse LHON mutation demonstrated reduced respiration, reduced ATP content and elevated production of mitochondrial reactive oxygen species (ROS). The generated resource of mouse mtDNA mutants will be useful both in modeling human mitochondrial disease and in understanding the mechanisms of ROS production mediated by mutations in mtDNA.


Asunto(s)
ADN Mitocondrial/química , Modelos Animales de Enfermedad , Ratones/genética , Enfermedades Mitocondriales/genética , Mutagénesis , Mutación , Animales , Ingeniería Celular/métodos , Línea Celular , Respiración de la Célula , Humanos , Especies Reactivas de Oxígeno/metabolismo
9.
Cardiol Young ; 26(4): 629-35, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26510606

RESUMEN

Common pulmonary vein atresia is a rare and usually fatal congenital anomaly, in which the pulmonary veins come together to form a confluence that does not connect to the left atrium. We report our experience with three cases of common pulmonary vein atresia and review the literature on this anomaly. The diagnosis of common pulmonary vein atresia must be entertained in any newborn that presents with cyanosis, refractory acidosis, and decreased systemic perfusion within the first 48 hours of life. Echocardiography is a useful screening tool, but cardiac catheterisation is the preferred diagnostic tool. Common pulmonary vein atresia can be fatal without surgical intervention, but survival after surgery continues to be poor.


Asunto(s)
Venas Pulmonares/anomalías , Anomalías Congénitas/diagnóstico por imagen , Resultado Fatal , Femenino , Humanos , Recién Nacido , Masculino
10.
Inorg Chem ; 53(14): 7485-99, 2014 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-24961904

RESUMEN

An experimental and computational study of correlations between solid-state structure and optical/electronic properties of cyclotrimeric gold(I) carbeniates, [Au3(RN═COR')3] (R, R' = H, Me, (n)Bu, or (c)Pe), is reported. Synthesis and structural and photophysical characterization of novel complexes [Au3(MeN═CO(n)Bu)3], [Au3((n)BuN═COMe)3], [Au3((n)BuN═CO(n)Bu)3], and [Au3((c)PeN═COMe)3] are presented. Changes in R and R' lead to distinctive variations in solid-state stacking, luminescence spectra, and conductive properties. Solid-state emission and excitation spectra for each complex display a remarkable dependence on the solid-state packing of the cyclotrimers. The electronic structure of [Au3(RN═COR')3] was investigated via molecular and solid-state simulations. Calculations on [Au3(HN═COH)3] models indicate that the infinitely extended chain of eclipsed structures with equidistant Au--Au intertrimer aurophilic bonding can have lower band gaps, smaller Stokes shifts, and reduced reorganization energies (λ). The action of one cyclotrimer as a molecular nanowire is demonstrated via fabrication of an organic field effect transistor and shown to produce a p-type field effect. Hole transport for the same cyclotrimer-doped within a poly(9-vinylcarbazole) host-produced a colossal increase in current density from ∼1 to ∼1000 mA/cm(2). Computations and experiments thus delineate the complex relationships between solid-state morphologies, electronic structures, and optoelectronic properties of gold(I) carbeniates.

11.
Microbiol Resour Announc ; : e0032124, 2024 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-38819140

RESUMEN

We present the complete mitochondrial genome of Carausius morosus from Salinas, CA. The mitochondrial genome of C. morosus is circular, AT rich (78.1%), and 16,671 bp in length. It consists of 13 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes and is identical in gene content to Carausius sp.

12.
J Environ Qual ; 52(1): 64-73, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36333932

RESUMEN

A saturated riparian buffer (SRB) is an edge-of-field conservation practice that intercepts tile drainage and reduces nitrate flux to nearby streams by redistributing the flow as shallow groundwater. In this study, a three-dimensional, finite-difference groundwater model representative of SRBs in central Iowa was developed to assess the flow of groundwater and implications for nitrate removal during spring conditions, when flow to the SRB is highest. The model reproduces field observations of water level with Nash-Sutcliffe efficiency of 0.68, which is deemed acceptable for hydrologic models. The modeling shows that groundwater flow is three-dimensional near the distribution pipe and the stream and primarily one-dimensional in the rest of the buffer. The path the water takes in flowing toward the stream depends on where it exits the distribution pipe. When nitrate is not limiting, the potential for nitrate removal depends on the length of the path-and thus travel time-and depth because denitrification potential varies with depth. Travel time Tt can be estimated well with slight modifications to a one-dimensional approximation: Tt = 1.11Lx /vx , where Lx is the buffer width and vx is a one-dimensional approximation of the average linear velocity of groundwater. Refining knowledge of SRB function is an important step toward enhancing design for improving water quality.


Asunto(s)
Agua Subterránea , Nitratos , Nitratos/análisis , Monitoreo del Ambiente , Calidad del Agua , Ríos
13.
J Clin Microbiol ; 50(5): 1783-6, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22403418

RESUMEN

The TaqMan real-time PCR assay was developed from the Blastomyces dermatitidis BAD1 gene promoter. The assay identified all haplotypes of B. dermatitidis and five of six positive paraffin-embedded tissues. The assay sensitivity threshold was 1 pg genomic DNA of the mold form and 2 CFU of the yeast form of B. dermatitidis. No cross-reactivity was observed against other fungal DNA. The assay allowed rapid (5-h) identification of B. dermatitidis from culture and from clinical specimens.


Asunto(s)
Blastomyces/aislamiento & purificación , Blastomicosis/diagnóstico , Técnicas de Laboratorio Clínico/métodos , Micología/métodos , Patología Molecular/métodos , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Animales , Blastomicosis/microbiología , ADN de Hongos/genética , Humanos , Regiones Promotoras Genéticas , Sensibilidad y Especificidad
14.
J Orthop Res ; 40(12): 2856-2864, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-35277882

RESUMEN

Ligamentous Lisfranc injuries cause debilitating pain and loss of function. Even small diastasis of this normally rigid joint after injury requires surgical treatment, but outcomes remain poor. Existing literature has compared the different surgical procedures using cadaveric models, but no approach has been recommended over others. This study uses a computational biomechanical approach consistent with a cadaveric study to evaluate the different procedures' ability to stabilize the Lisfranc joint without inducing secondary consequences. A validated rigid body model for the cadaver foot with a Lisfranc injury was extended to compare the stability of four different surgical repairs-three open reduction and internal fixation procedures with different hardware (cannulated screws, endobuttons, and screws with a dorsal plate) and primary arthrodesis with screws. Forces calculated from the rigid body model for 50% partial weight bearing provided boundary conditions for a finite element model of the surgical repairs. Comparing the different surgical procedures, the open reduction and internal fixation with screws and primary arthrodesis with screws showed the most stable postoperative Lisfranc joint. However, the use of cannulated screws for fixation showed regions of high stress that may be susceptible to breakage and also resulted in higher contact forces in joints adjacent to the surgery site. Endobuttons and dorsal plates did not restore sufficient stability. Since all procedures showed different points of concern that could impact outcomes, additional surgical approaches could be needed in the future. This study offers a standard protocol for benchmarking the new procedures against those currently used.


Asunto(s)
Huesos Metatarsianos , Humanos , Huesos Metatarsianos/lesiones , Fijación Interna de Fracturas/métodos , Placas Óseas , Artrodesis , Cadáver
15.
J Environ Psychol ; 772021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34720327

RESUMEN

In the United States, people of color from low income and working-class backgrounds are at disproportionate risk to pollution and other environmental stressors. These environmental justice communities (EJCs) can also experience increased risk when a natural disaster collides with a preexisting environmental risk. The current research is an exploratory field study that examines perceptions of environmental risk after a natural disaster and how meaningful a public apology would be in three communities. Residents (N=161) in two EJCs and a community without documented risks reported their environmental concerns and perceptions of public apologies. Overall, EJC residents reported greater concern about chemical hazard exposure than did residents with decreased risk. Furthermore, chemical exposure concerns facilitated public apology meaningfulness within the EJCs, but not in the decreased risk community.

16.
West J Emerg Med ; 22(6): 1335-1340, 2021 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-34787559

RESUMEN

INTRODUCTION: To determine the accuracy of landmark-guided shoulder joint injections (LGI) with point-of-care ultrasound for patients with anterior shoulder dislocations. METHODS: Patients with anterior shoulder dislocations who underwent LGI were enrolled at our tertiary-care and trauma center. LGI attempts were recorded by an ultrasound fellowship-trained ED physician who determined if they were placed successfully. Pain and satisfaction scores were recorded. RESULTS: A total of 34 patients with anterior shoulder dislocation and their treating ED physicians were enrolled. 41.1% of all LGI were determined to be misplaced (n=14). Patients with successful LGI had a greater decrease in mean pain scores post-LGI. CONCLUSIONS: LGI had a substantial failure rate in our study. Using ultrasound-guidance to assist intra-articular injections may increase its accuracy and thus reduce pain and the need for subsequent procedural sedation.


Asunto(s)
Luxación del Hombro , Articulación del Hombro , Humanos , Inyecciones Intraarticulares , Luxación del Hombro/diagnóstico por imagen , Luxación del Hombro/tratamiento farmacológico , Articulación del Hombro/diagnóstico por imagen , Ultrasonografía , Ultrasonografía Intervencional
17.
Int J Comput Assist Radiol Surg ; 16(8): 1381-1391, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34146225

RESUMEN

PURPOSE: Rhinoplasty is one of the most common and challenging plastic surgery procedures. Facial analysis is a crucial step in planning. Utilizing three-dimensional (3D) model of a patient's face is an emerging way of performing facial analysis. This paper evaluates the agreement and reliability of facial measurements taken using a web app, located at digitized-rhinoplasty.com, that utilizes 3D models of the patient's face. METHODS: Eleven measurements were calculated on 16 human subjects. Three methods of measurements were performed: direct measurements on human subjects' faces, measurements on 2D photographs, and measurements on 3D models of face scans. The Bland-Altman plot is used for testing the agreement between the web app and the well-known Blender 3D modeling software. Intra-rater and inter-rater reliability was calculated and compared for 2D and 3D methods using the intraclass correlation coefficient (ICC) method. The statistical analysis methods were checked for the normality and homoscedasticity assumptions. RESULTS: The results indicate that the web app and Blender software show agreement within 95% confidence limits. The web app performs well in intra-rater and inter-rater reliability statistical analysis. The web app's reliability scores are consistently better than facial analysis software which was found highly reliable in a previous study. We also compare the methods of measurements in terms of time, ease of use, and cost. CONCLUSION: The utilization of 3D computer modeling for facial analysis has its advantages and started to become more common due to recent advances in technology. The web app utilizes 3D face scans for pre-operative planning and post-operative evaluation of facial surgeries. The web app performs well in agreement and inter-/intra-reliability analysis and performs consistently better than software that works utilizing 2D photographs. The web app provides accurate, repeatable, affordable, and fast facial measurements for facial analysis when compared to direct and 2D methods.


Asunto(s)
Imagenología Tridimensional/métodos , Rinoplastia/métodos , Programas Informáticos , Adolescente , Adulto , Estudios Cruzados , Cara , Femenino , Humanos , Internet , Masculino , Persona de Mediana Edad , Periodo Posoperatorio , Curva ROC , Reproducibilidad de los Resultados , Adulto Joven
18.
J Environ Qual ; 50(6): 1430-1439, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34390594

RESUMEN

Saturated riparian buffers (SRBs) reduce nitrate export from agricultural tile drainage by infusing drainage water into carbon-rich riparian soils where denitrification and plant uptake occur. The water quality benefits from SRBs are well documented, but uncertainties about their effect on streambank stability have led to design standards that limit the maximum bank height and minimum buffer width, thus reducing the number of suitable candidate sites. In this study, the relationship between SRB design and streambank stability was examined through numerical slope stability modeling and validated using field sites. At the study sites, the addition of SRB flow increased the probability of failure by less than 3% for both simulated dry and rainfall scenarios. Furthermore, the simulations provide no evidence to support excluding potential sites based on bank height alone. Multivariate analysis of dimensionless parameters developed for SRB flow conditions was used to predict the factor of safety as a function of the SRB site and design conditions. The equation presented allows designers to assess the stability of a potential site where bank failure poses a heightened risk. The results of this study alleviate the need for extensive geotechnical evaluations at future SRB sites and could increase SRB implementation by expanding the range of eligible sites.


Asunto(s)
Monitoreo del Ambiente , Ríos , Agricultura , Nitratos/análisis , Suelo
20.
J Environ Qual ; 49(6): 1624-1632, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33145805

RESUMEN

A saturated riparian buffer (SRB) is an edge-of-field conservation practice that reduces nitrate export from agricultural lands by redistributing tile drainage as shallow groundwater and allowing for denitrification and plant uptake. We propose an approach to improve the design of SRBs by analyzing a tradeoff in choosing the SRB width, and we apply the approach to six sites with SRBs in central Iowa. A larger width allows for more residence time, which increases the opportunity for removing nitrate that enters the buffer. However, because the SRBs considered here treat only a portion of the tile flow when it is large, for the same difference in hydraulic head, a smaller width allows more of the total tile flow to enter the buffer and therefore treats more of the drainage. By maximizing the effectiveness of nitrate removal, defined as the ratio of total nitrate removed by the SRB to total nitrate leaving the field in tile drainage, an equation for the optimal width was derived in terms of soil properties, denitrification rates, and head difference. All six sites with existing SRBs considered here have optimal widths smaller than the current width, and two are below the minimum width listed in current design standards. In terms of uncertainty, the main challenges in computing the optimal width for a site are estimating the removal coefficient for nitrate and determining the saturated hydraulic conductivity. Nevertheless, including a width that accounts for site conditions in the design standards would improve water quality locally and regionally.


Asunto(s)
Agua Subterránea , Nitratos , Tampones (Química) , Iowa , Nitratos/análisis , Suelo
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