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US Labeling requirements for cosmetic products are established by the US Food and Drug Administration (USFDA) and detailed in the Code of Federal Regulations (21 CFR 701.3).1 Over 16,000 cosmetic ingredients names have been documented and ingredient nomenclature resources are recommended by the USFDA for use by manufacturers and suppliers.
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Cosméticos , Estados Unidos , Humanos , Cosméticos/efectos adversos , United States Food and Drug AdministrationRESUMEN
Experiments reveal a wide discrepancy between the permeability of porous media containing colloid deposits and the available predictive equations. Evidence suggests that this discrepancy results, in part, from the predictive equations failing to account for colloid deposit morphology. This article reports a series of experiments using static light scattering (SLS) to characterize colloid deposit morphology within refractive index matched (RIM) porous media during flow through a column. Real time measurements of permeability, specific deposit, deposit fractal dimension, and deposit radius of gyration, at different vertical positions, were conducted with initially clean porous media at various ionic strengths and fluid velocities. Decreased permeability (i.e., increased clogging) corresponded with higher specific deposit, lower fractal dimension, and smaller radius of gyration. During deposition, fractal dimension, radius of gyration, and permeability decreased with increasing specific deposit. During flushing with colloid-free fluid, these trends reversed, with increased fractal dimension, radius of gyration, and permeability. These observations suggest a deposition scenario in which large and uniform aggregates become deposits, which reduce porosity, lead to higher fluid shear forces, which then decompose the deposits, filling the pore space with small and dendritic fragments of aggregate.
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Coloides/química , Fractales , Filtración/instrumentación , Concentración Osmolar , Permeabilidad , Porosidad , Dispersión de RadiaciónRESUMEN
Understanding the dynamics of surface bubble formation and growth on heated surfaces holds significant implications for diverse modern technologies. While such investigations are traditionally confined to terrestrial conditions, the expansion of space exploration and economy necessitates insights into thermal bubble phenomena in microgravity. In this work, we conduct experiments in the International Space Station to study surface bubble nucleation and growth in a microgravity environment and compare the results to those on Earth. Our findings reveal significantly accelerated bubble nucleation and growth rates, outpacing the terrestrial rates by up to ~30 times. Our thermofluidic simulations confirm the role of gravity-induced thermal convective flow, which dissipates heat from the substrate surface and thus influences bubble nucleation. In microgravity, the influence of thermal convective flow diminishes, resulting in localized heat at the substrate surface, which leads to faster temperature rise. This unique condition enables quicker bubble nucleation and growth. Moreover, we highlight the influence of surface microstructure geometries on bubble nucleation. Acting as heat-transfer fins, the geometries of the microstructures influence heat transfer from the substrate to the water. Finer microstructures, which have larger specific surface areas, enhance surface-to-liquid heat transfer and thus reduce the rate of surface temperature rise, leading to slower bubble nucleation. Our experimental and simulation results provide insights into thermal bubble dynamics in microgravity, which may help design thermal management solutions and develop bubble-based sensing technologies.
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Astronauts experience significant and rapid bone loss as a result of an extended stay in space, making the International Space Station (ISS) the perfect laboratory for studying osteoporosis due to the accelerated nature of bone loss on the ISS. This prompts the question, how does the lack of load due to zero-gravity propagate to bone-forming cells, human fetal osteoblasts (hFOBs), altering their maturation to mineralization? Here, we aim to study the mechanotransduction mechanisms by which bone loss occurs in microgravity. Two automated experiments, 4 microfluidic chips capable of measuring single-cell mechanics of hFOBs via aspiration and cell spheroids incubated in pressure-controlled chambers, were each integrated into a CubeLab deployed to the ISS National Laboratory. For the first experiment, we report protrusion measurements of aspirated cells after exposure to microgravity at the ISS and compare these results to ground control conducted inside the CubeLab. Our analysis revealed slightly elongated protrusions for space samples compared to ground samples indicating softening of hFOB cells in microgravity. In the second experiment, we encapsulated osteoblast spheroids in collagen gel and incubated the samples in pressure-controlled chambers. We found that microgravity significantly reduced filamentous actin levels in the hFOB spheroids. When subjected to pressure, the spheroids exhibited increased pSMAD1/5/9 expression, regardless of the microgravity condition. Moreover, microgravity reduced YAP expression, while pressure increased YAP levels, thus restoring YAP expression for spheroids in microgravity. Our study provides insights into the influence of microgravity on the mechanical properties of bone cells and the impact of compressive pressure on cell behavior and signaling in space.
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Astronauts experience significant and rapid bone loss as a result of an extended stay in space, making the International Space Station (ISS) the perfect laboratory for studying osteoporosis due to the accelerated nature of bone loss on the ISS. This prompts the question, how does the lack of load due to zero-gravity propagate to bone-forming cells, human fetal osteoblasts (hFOBs), altering their maturation to mineralization? Here, we aim to study the mechanotransduction mechanisms by which bone loss occurs in microgravity. Two automated experiments, microfluidic chips capable of measuring single-cell mechanics via aspiration and cell spheroids incubated in pressure-controlled chambers, were each integrated into a CubeLab deployed to the ISS National Laboratory. For the first experiment, we report protrusion measurements of aspirated cells after exposure to microgravity at the ISS and compare these results to ground control conducted inside the CubeLab. We found slightly elongated protrusions for space samples compared to ground samples indicating softening of hFOB cells in microgravity. In the second experiment, we encapsulated osteoblast spheroids in collagen gel and incubated the samples in pressure-controlled chambers. We found that microgravity significantly reduced filamentous actin levels in the hFOB spheroids. When subjected to pressure, the spheroids exhibited increased pSMAD1/5/9 expression, regardless of the microgravity condition. Moreover, microgravity reduced YAP expression, while pressure increased YAP levels, thus restoring YAP expression for spheroids in microgravity. Our study provides insights into the influence of microgravity on the mechanical properties of bone cells and the impact of compressive pressure on cell signaling in space.
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Topical tretinoin has been approved for use in dermatology for 40 years and is currently approved for the treatment of acne vulgaris and photodamage. During this time, topical tretinoin has accumulated significant efficacy and safety data in the treatment of acne and photodamaged skin and demonstrated clinical potential for treating a range of other dermatologic conditions. The diverse effects may be due to complex underlying mechanisms of action associated with tretinoin, including keratolytic activity, collagenesis, and other mechanisms associated with the activation of nuclear retinoic acid receptors (RARα, RARß, and RARγ). In this article, we review the history of topical tretinoin use to date and outline emerging research suggesting that topical tretinoin may have potential clinical use for treating a multitude of other dermatological conditions when used either as monotherapy or in combination with other agents. We also describe newer formulations of topical tretinoin that have been designed to reduce irritation potential. In light of the substantial history of safety and efficacy of topical tretinoin in acne and photodamage, we speculate that it holds promise in treating many additional dermatological conditions, which may be explored in future research.
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Envejecimiento de la Piel/efectos de los fármacos , Tretinoina/uso terapéutico , Acné Vulgar/tratamiento farmacológico , Acné Vulgar/patología , Administración Cutánea , Humanos , Queratolíticos/administración & dosificación , Queratolíticos/efectos adversos , Queratolíticos/uso terapéutico , Enfermedades de la Piel/tratamiento farmacológico , Enfermedades de la Piel/patología , Tretinoina/administración & dosificación , Tretinoina/efectos adversos , Rayos Ultravioleta/efectos adversosRESUMEN
Because tires contain approximately 1-2% zinc by weight, zinc leaching is an environmental concern associated with civil engineering applications of tire crumb rubber. An assessment of zinc leaching data from 14 studies in the published literature indicates that increasing zinc leaching is associated with lower pH and longer leaching times, but the data display a wide range of zinc concentrations, and do not address the effect of crumb rubber size or the dynamics of zinc leaching during flow through porous crumb rubber. The present study was undertaken to investigate the effect of crumb rubber size using the synthetic precipitation leaching procedure (SPLP), the effect of exposure time using quiescent batch leaching tests, and the dynamics of zinc leaching using column tests. Results indicate that zinc leaching from tire crumb rubber increases with smaller crumb rubber and longer exposure time. Results from SPLP and quiescent batch leaching tests are interpreted with a single-parameter leaching model that predicts a constant rate of zinc leaching up to 96 h. Breakthrough curves from column tests displayed an initial pulse of elevated zinc concentration (~3 mg/L) before settling down to a steady-state value (~0.2 mg/L), and were modeled with the software package HYDRUS-1D. Washing crumb rubber reduces this initial pulse but does not change the steady-state value. No leaching experiment significantly reduced the reservoir of zinc in the crumb rubber.
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Contaminantes Ambientales/aislamiento & purificación , Goma/química , Zinc/aislamiento & purificación , Modelos QuímicosRESUMEN
This paper presents a case example of the Indigenous Evaluation Framework as applied to a science, technology, engineering, and mathematics (STEM) education pilot program. Indigenous methodologies include knowledge and data that are inclusive of historically marginalized groups, are highly meaningful, valid, and useful for all. A paradigm shift from Western evaluation methodologies to Indigenous evaluation is necessary when evaluating STEM programs that are committed to increasing recruitment, retention, and graduation of students from historically marginalized groups. This paper describes the use of the Indigenous Evaluation Framework during the first two years of the newly created Environmental Stewardship of Indigenous Lands program at the University of Colorado Denver. We discuss the importance of the Indigenous Evaluation Framework and how it informs the development and continued improvements to the program that also provides agency to program leads and participants.
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Ingeniería , Tecnología , Ingeniería/educación , Humanos , Matemática , Evaluación de Programas y Proyectos de Salud , Tecnología/educación , UniversidadesRESUMEN
BACKGROUND: Topical retinoids have been in clinical use for the treatment of chronic skin conditions, including acne, photodamage, and psoriasis, for 30 years. OBJECTIVE: A systematic literature review was conducted to assess the incidence of noncutaneous adverse events (AE) among patients treated with topical retinoids with a focus on topical tretinoin studies reported before the Veterans Affairs Topical Tretinoin Chemoprevention trial. METHODS: Electronic literature searches were conducted in Embase and MEDLINE for literature reporting development of nonteratogenic, noncutaneous AE among patients treated with topical retinoids published through September 2008. RESULTS: The search yielded 2778 citations, of which 20 studies met inclusion criteria. Tretinoin was used in 14 of the studies. Other retinoids assessed included isotretinoin, adapalene, alitretinoin, and tazarotene. Within patients receiving topical tretinoin, 27.9% reported the occurrence of at least one noncutaneous AE. The majority of noncutaneous AE were transient and judged not to be related to tretinoin treatment. LIMITATIONS: The conclusions of this study apply largely to tretinoin compared with other topical retinoids. Many of the included trials were designed to evaluate the efficacy of topical treatment and reporting of safety events concentrated on incidence of localized AE, rather than systemic or noncutaneous events. CONCLUSION: We found no clear evidence of a relationship between the use of topical tretinoin and the development of noncutaneous AE before a recent report of excess mortality in a clinical trial. The majority of noncutaneous AE reported by patients receiving topical retinoids consisted of nonsevere, nonspecific symptoms that were judged not to be related to treatment.
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Fármacos Dermatológicos/administración & dosificación , Fármacos Dermatológicos/efectos adversos , Tretinoina/administración & dosificación , Tretinoina/efectos adversos , Administración Tópica , HumanosRESUMEN
Compost mulches have potential to significantly offset on- and off-site environmental impacts resulting from mechanical soil disturbances and training manoeuvres on military training ranges. N and P transport was investigated in runoff from compost mulch berms made from various organic waste materials in combination with each other and with soil on a simulated military training landscape in north Alabama in 2007 and 2008. Berms were constructed using composted municipal yard waste (YW), wood chips (WC), pine bark fines (PB), and soil (SL) mixed in eight different proportions. Berms made from 100% soil which had a cumulative runoff PO(4)-P content of 12 mg L(-1) posed the greatest threat of negatively impacting the environment from inorganic P transport. Using compost mulch material with 40% soil to build berms reduced the potential for yard waste and wood chips to cause off-site negative environmental impacts from total dissolved solids, N, and P transport. Berms made from 100% pine bark fines which had cumulative runoff values of 760, 9, 22 and 5 mg L( -1), respectively, of TDS, NH(4)-N, NO(3)-N, and PO( 4)-P had the least potential to cause negative off-site environmental impact. To prevent negative impacts of nutrient transport in runoff from berms on training landscapes, the sites need to be well buffered to hydrologically isolate them from adjoining ecosystems.
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Nitrógeno/análisis , Fósforo/análisis , Contaminantes del Suelo/análisis , Contaminantes del Agua/análisis , Alabama , Monitoreo del Ambiente , Suelo , Movimientos del AguaRESUMEN
Evaluating the impact of urban development on natural ecosystem processes has become an increasingly complex task for planners, environmental scientists, and engineers. As the built environment continues to grow, unregulated nonpoint pollutants from increased human activity and large-scale development severely stress urban streams and lakes resulting in their currently impaired or degraded state. In response, integrated water quality management programs have been adopted to address these unregulated nonpoint pollutants by utilizing best management practices (BMPs) that treat runoff as close to the source as possible. Knowing where to install effective BMPs is no trivial task, considering budget constraints and the spatially extensive nature of nonpoint stormwater runoff. Accordingly, this paper presents an initial, straightforward and cost-effective methodology to identify critical nonpoint pollutant source watersheds through correlation of water quality with land use. Through an illustrative application to metropolitan Denver, Colorado, it is shown how this method can be used to aid stormwater professionals to evaluate and specify retrofit locations in need of water quality treatment features reduce, capture and treat stormwater runoff prior to entering receiving waters.
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Lluvia , Urbanización , Movimientos del Agua , Ciudades , Colorado , Contaminación del AguaRESUMEN
BACKGROUND: Because the scientific literature on the pharmacotherapy of attention-deficit/hyperactivity disorder (ADHD) is almost entirely based on the results of studies in samples consisting primarily of boys, much is unknown about the treatment response in girls. OBJECTIVE: This post hoc analysis compared the efficacy, tolerability, and time course of the effect of mixed amphetamine salts extended release (MAS XR) and atomoxetine in school-age girls with ADHD. METHODS: This was an intent-to-treat subanalysis of the data from girls enrolled in a multicenter, 18-day, randomized, double-blind, parallel-group, forced dose-titration, laboratory school study enrolling boys and girls aged 6 to 12 years with ADHD. The study compared the efficacy, tolerability, and time course of the effect of increasing doses of MAS XR (10, 20, and 30 mg/d) and atomoxetine (0.5 and 1.2 mg/kg per day). The laboratory school sessions were organized in cycles to include 12 hours of observation. Efficacy measures included the SKAMP (Swanson, Kotkin, Agler, M-Flynn, and Pelham) deportment rating subscale, the SKAMP attention rating subscale, and academic testing (number of math problems attempted and answered correctly). Adverse events were assessed throughout the study period. Tolerability and efficacy measures were assessed during laboratory school visits on days 7, 14, and 21. RESULTS: This subanalysis included 57 girls (median age, 9 years; 49.1% white, 22.8% black, 17.5% Hispanic) with a diagnosis of ADHD, combined subtype. Twenty-six girls were randomized to receive MAS XR and 31 were randomized to receive atomoxetine. Mean SKAMP deportment and attention subscale scores in the 2 groups were similar at baseline. Mean changes from baseline were significantly greater for MAS XR compared with atomoxetine on the SKAMP deportment score (-0.48 vs -0.04, respectively; P<0.001) and SKAMP attention score (-0.45 vs -0.05; P<0.001). The time course of medication effect, based on change from baseline in SKAMP deportment scores, indicated 12-hour efficacy for MAS XR at hours 2, 4.5, 7, 9.5, and 12 (all time points, P<0.01 vs baseline) but not for atomoxetine. At the end of the study, both treatment groups had a significant increase from baseline in the mean number of math problems attempted and answered correctly (P<0.001). Girls who received MAS XR attempted significantly greater numbers of problems compared with those who received atomoxetine (P=0.04). Both MAS XR and atomoxetine were well tolerated. The most frequently occurring treatment-related adverse events in girls receiving MAS XR were decreased appetite (40.7%), upper abdominal pain (29.6%), insomnia (25.9%), and headache (14.8%). The most frequently occurring treatment-related adverse events in girls receiving atomoxetine were somnolence (28.1%), upper abdominal pain (15.6%), vomiting (15.6%), nausea (12.5%), and decreased appetite (12.5%). CONCLUSION: This post hoc analysis in a subpopulation of girls with ADHD, combined subtype, found that 18-day treatment with MAS XR was significantly more effective than atomoxetine in terms of ratings of classroom behavior, attention, and academic productivity.
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Inhibidores de Captación Adrenérgica/uso terapéutico , Anfetaminas/uso terapéutico , Trastorno por Déficit de Atención con Hiperactividad/tratamiento farmacológico , Estimulantes del Sistema Nervioso Central/uso terapéutico , Propilaminas/uso terapéutico , Clorhidrato de Atomoxetina , Niño , Preparaciones de Acción Retardada/uso terapéutico , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Femenino , Humanos , Escalas de Valoración Psiquiátrica , Resultado del TratamientoRESUMEN
BACKGROUND: Hard water is associated with atopic dermatitis (eczema). We wanted to determine if a baby cleanser and its individual components altered free ionized calcium (Ca2+) in a simulated hard water baby bath. For these studies, an in vitro determination of free Ca2+ in a simulated hard water baby bath, and an in vivo exploratory study of free Ca2+ absorption into skin from hard water were performed. METHODS: Free Ca2+ was measured with an ion-sensitive electrode in vitro in hard water (100-500 ppm, Ca2+) before and after addition of the cleanser and/or its components. In an exploratory study, absorption of Ca2+ into skin from hard water was determined in three female participants (aged 21-29 years). RESULTS: At an in-use dilution of 1%, the test cleanser reduced free Ca2+ from ~500 ppm to <200 ppm; a 10% in-use dilution bound virtually all free Ca2+. The anionic surfactant component contributed the most to this effect. In the exploratory in vivo study, we measured a reduction of ~15% in free Ca2+ from simulated hard water over 10 minutes. CONCLUSION: Baby cleansers can bind free Ca2+ and reduce the effective water hardness of bath water. Reducing the amount of free Ca2+ in the water will reduce the availability of the ion for binding to the skin. Altering or reducing free Ca2+ concentrations in bath water may be an important parameter in creating the ideal baby bath.
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Mixed amphetamine salts extended release (MAS XR; Adderall XR) and atomoxetine (Strattera) were compared in children 6 to 12 years old with attention deficit/hyperactivity disorder (ADHD) combined or hyperactive/impulsive type in a randomized, double-blind, multicenter, parallel-group, forced-dose-escalation laboratory school study. Primary efficacy measure was the SKAMP (Swanson, Kotkin, Agler, M-Flynn, and Pelham) behavioral rating scale. Changes in mean SKAMP deportment scores from baseline were significantly greater for MAS XR (n = 102) than for atomoxetine (n = 101) overall (-0.56 and -0.13, respectively; p < .0001) and at each week (p < .001). Adverse events were similar for both treatment groups. The extended time course of action and greater therapeutic efficacy of MAS XR suggests that it is more effective than atomoxetine in children with ADHD.
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Anfetaminas/uso terapéutico , Trastorno por Déficit de Atención con Hiperactividad/tratamiento farmacológico , Estimulantes del Sistema Nervioso Central/uso terapéutico , Propilaminas/uso terapéutico , Clorhidrato de Atomoxetina , Niño , Preparaciones de Acción Retardada/administración & dosificación , Preparaciones de Acción Retardada/farmacología , Preparaciones de Acción Retardada/uso terapéutico , Método Doble Ciego , Esquema de Medicación , Femenino , Humanos , Masculino , Norepinefrina/metabolismo , Propilaminas/administración & dosificación , Propilaminas/farmacología , Resultado del TratamientoRESUMEN
The cumulative irritation test (CIT) is an accepted method used to evaluate the skin irritation potential and safety of individual ingredients and formulas of leave-on skin care and cosmetic compounds. Here, we report the results of CITs collected by JOHNSON & JOHNSON Consumer Companies, Inc. (Skillman, NJ), part of an extensive tiered program to evaluate product safety. In the CIT, test formulations were applied to the skin of adults (18-70 years) with no known skin disease or allergies, 3 times per week for 2 weeks using semi-occlusive clinical patches. Preservatives were 1 of up to 16 components of test formulas, and included ethylenediaminetetraacetic acid, diazolidinyl urea, 1,3-Bis(hydroxymethyl)-5,5-dimethylimidazolidine-2,4-dione, parabens, isothiazolinone, phenoxyethanol, sorbates, or benzoates. Skin sites were scored after each patch removal using a 5-point scale, with 0 = no visible reaction and 4 = erythema, marked edema, or substantial vesiculation. Scores were reported as percentage of maximal irritation score. Data were analyzed from 1363 CIT studies (over 45 000 subjects). There were no significant differences in percentage of maximal scores between formulas grouped by preservative types (p > .1). Median score across the entire dataset was 0.44, with most formulas showing none or mild irritation. Although seasonal variations were observed, no correlation was noted between score and preservative concentration. In conclusion, in a large, normal subject dataset, preservatives at typical in-use concentrations did not appear to contribute to skin irritation.
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Cosméticos/toxicidad , Erupciones por Medicamentos/etiología , Crema para la Piel/toxicidad , Piel/efectos de los fármacos , Adolescente , Adulto , Anciano , Erupciones por Medicamentos/fisiopatología , Edema/inducido químicamente , Edema/fisiopatología , Eritema/inducido químicamente , Eritema/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Estaciones del Año , Índice de Severidad de la Enfermedad , Enfermedades de la Piel/inducido químicamente , Enfermedades de la Piel/fisiopatología , Pruebas de Irritación de la Piel , Estados Unidos , Adulto JovenRESUMEN
Colloidal phenomena in porous media, natural or engineered, are important in a breadth of science and technology applications, but fundamental understanding is hampered by the difficulty in measuring colloid deposit morphology in situ. To partially address this need, this paper describes a static light scattering apparatus using a flow cell filled with refractive index matched (RIM) porous media, allowing real-time measurement of colloidal phenomena as a function of depth within the flow cell. A laser interacts with the colloids in the pore space and their structures, but not with the RIM media. The intensity of scattered light is measured as a function of scattering angle, which allows characterization of colloid deposit morphology as a fractal dimension and a radius of gyration. In parallel, fluid discharge rate and pressure drop are recorded to determine permeability, a key parameter for any application involving flow through porous media. This apparatus should prove useful in any application requiring characterization of colloidal phenomena within porous media. Additionally, this paper describes how to use granular Nafion as RIM porous media.
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BACKGROUND: The right to self-determination is fundamental in clinical ethics. End-of-life conversations and advance directives (ADs), in addition to preserving this right, have been shown to decrease the likelihood of in-hospital death, improve the quality of care, and lower health costs in the final week of life. Despite these benefits, the rates of AD documentation are poor. OBJECTIVE: Our aim was to assess the effectiveness of an electronic medical record (EMR)-based reminder in improving AD documentation rates. METHODS: We conducted a prospective quality improvement study in outpatients at the Grady Memorial Hospital Purple Pod Clinic in Atlanta, GA. Using the EMR system EPIC we set to implement a reminder system consisting of the addition of "Advanced Directives Counseling" to the problem list (ADPL) of 50% of outpatients meeting one of the following criteria: age >65 years, congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), acquired immune deficiency syndrome (AIDS), malignancy, cirrhosis, end-stage renal disease (ESRD), or stroke. Primary care physicians were encouraged to document ADs for all patients. The number of patients with documented ADs was assessed at 6 months post-test of change. RESULTS: A total of 588 patient charts were screened by seven providers, with 157 patients meeting the predefined criteria for AD documentation. During a 6-month period, 64 patients were seen in the clinic; 38 had AD on their problem list, and 26 did not. Seventy-six percent of charts with ADPL had documentation of an AD. Only 11.5% of those without ADPL had an AD documented. CONCLUSIONS: EMR-based reminders are effective in improving documentation rates of ADs. Further research is needed to establish whether improved documentation impacts inpatient management and costs of care.
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Directivas Anticipadas , Instituciones de Atención Ambulatoria , Documentación/normas , Registros Electrónicos de Salud , Planificación Anticipada de Atención , Anciano , Humanos , Estudios Prospectivos , Mejoramiento de la Calidad , Enfermo TerminalRESUMEN
Colloidal phenomena play an important role in natural porous media, where they influence soil structuring, contaminant migration, filtration, and clogging. Several methods are available to measure pore space geometry within porous media, but these methods have limited applicability when the relevant physical, chemical, or biological processes are dominated by dynamic colloidal phenomena. Here we report a new technique to quantify colloid aggregate structure as a fractal dimension using static light scattering within index-matched porous media (granular Nafion). We validate the method by obtaining consistent results for scattering in suspensions and in porous media, and verify that multiple scattering at environmentally relevant colloid concentrations does not affect the determination of fractal dimension. We also observe restructuring of aggregates during homogenization in the porous media, indicated by an apparent increase in fractal dimension, which can be explained by an analysis of the fluid shear stress caused by repeated inversions of test tubes either containing or not containing granular media. This technique will permit progress in obtaining fundamental descriptions of colloidal phenomena in porous media.