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A simulated grazing was developed with Brachiaria decumbens cv. Basilisk, to study the performance of dairy cows during rainy season in two grazing intensities: T1 = 75 and T2 = 150 LAU ha-1 day-1. Twenty Siboney crossbred cows were studied, between the second and third lactation, with 480 ± 8 kg of body weight (10 animals treatment-1), grazing 15 hours a day. InfoStat statistical program, version 12.0, was used for data processing. T2 animals showed lower grass availability (P = 0.0072) and intake decrease (P = 0.0362) (24.35 vs. 17.57 and 12.77 vs. 11.33 kg DM animal-1 day-1 for availability and intake of animals of 75 and 150 LAU ha-1 day-1). No differences were reported in individual production per cow and dairy components. However, production per area increased (P = 0.0001) by 1.74 times in T2 with respect to T1 (3,279.99 and 5,722.71 kg of milk ha-1 rainy season-1, for T1 and T2, respectively). Production cost of a liter of milk increased by 11.8 % in the treatment with the lowest intensity (2.17 vs. 1.96 $ L-1, for 75 and 150 LAU ha-1 day-1). Results indicate that animals from the treatment with 150 LAU ha-1 day-1 showed no differences in individual production, although they increased productivity per grazing area by 2,842.72 L, and decreased costs by 0.21 $ produced L-1. [ABSTRACT FROM AUTHOR]

The study was carried out in two dairy farms of Dos Ríos enterprise, during 2015 and 2016, in order to identify the main factors that influence dairy production. In the analysis, ten variables with the highest preponderance were identified, grouped into four principal components (PC), which explained 79.6 % of the variance. As a result of cluster analysis, four groups were f ormed, which respond, in a general sense, to each dairy farm at every season. Impact factors of each combination, principal component vs. group, were identified. The production (PC1) in dry period showed values of -0.257 and -0.815, for farms 16 and 17, respectively, related to the high stocking rate and low proportion of biomass bank in dairy 17. Herd (PC2) showed a negative impact on farm 16, due to the low number of animals that it uses with respect to dairy 17. Reproduction (PC3) presented a negative impact in both units, which was very similar during rainy season. This phenomenon indicates a greater number of births in dry season, which is not suitable in tropical exploitation systems based on pastures and forages. Milk quality (PC4) showed negative values in farm 16 during rainy season, due to mastitis. The results allowed to assess the factors with the greatest impact, average by groups and PC, and made it possible to identify, with certainty, the difficulties in the production system, so that strategies could be implemented to minimize or eliminate them. [ABSTRACT FROM AUTHOR]

A simulated grazing system was developed, using a total of 2.66 hectares, established with the variety Brachiaria decumbens vc. Basilisk; with the objective of studying their performance under dry conditions and without fertilization, subjected to two grazing intensities (GI): GI1 = 75 and GI2 = 150 LAU ha-1 day-1, during the rainy period. It was worked with 20 crossbred Siboney dairy cows between the second and third lactation (10 animals treatment-1), the animals grazed 15 hours a day. The areas under study showed an increase (P <0.05) in the Brachiaria proportion, in 7.9 and 13.2 %, for 75 and 150 LAU ha-1 day-1, respectively. The areas subjected to the highest intensity, showed higher availability of DM ha-1 paddock-1 (P <0.01) in 39.9 % (1 831.05 vs 2 562.11 kg DM ha-1 rotation-1, for 75 and 150 LAU ha-1 day-1, respectively); likewise, the grass yield was favored (P <0.05) in 23.9 % when it was submitted to 150 LAU ha-1 day-1. There were not differences in the bromatological composition of the grass. The obtained results, under these conditions, show that the Basilisk grass variety, subjected to grazing intensity of 150 LAU ha-1 day-1, maintains higher stability and likewise showed higher availability and grass yield, not affecting the bromatological quality of it. [ABSTRACT FROM AUTHOR]

During two years, the fractionation, one or four times a day, of the supplementation with fresh semi-integral diet was evaluated in dairy cattle with a restricted grazing management. A total of 54 Criollo crossbreed cows were randomLy distributed in two treatments: I) supply of the fresh semi-integral diet once a day and II) supply of the diet four times a day. The results showed that when the semi-integral diet was offered four times a day, the total dry matter intake increased (P <0.05) in 8.1 and 9.3 %, in relation to the supply once a day in the rainy and dry season, respectively. This increase in the total dry matter intake is directly related to the increase (P <0.05) of the semi-integral diet, which does not differ in its intake in the rainy season, but this increased in15.4 % in the dry season, 7.12 vs. 8.22 kg DM diet cow-1 day-1. The milk production increased (P <0.01) in 4.5 and 8.6 %, when supplying the diet four times a day in the rainy and dry season, respectively (7.76 vs. 8.11 and 6.07 vs. 6.59 kg cow-1 day-1, for one and four times the supply in the rainy and dry season, respectively). Similarly, the milk quality improved in the studied components. The study shows that the fractionation of the supplementation with fresh semi-integral diet increases the milk productivity and improves the milk quality, without showing effect on the body condition of the animals. [ABSTRACT FROM AUTHOR]

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Se muestran los principales resultados obtenidos en producción de leche bovina en las condiciones de Cuba, con el pasto como alimento base. Con la interacción adecuada de las cargas y variedades de pasto, se alcanzaron producciones lácteas entre 8 y 9 kg d-1 durante la época de lluvias, con carga de 3.0 vacas ha-1 en bermuda cruzada (Cynodon dactylon), 4.0 vacas ha-1 en pangola (Digitaria decumbens Stent) y 5.0 vacas ha-1 en pasto estrella (Cynodon nlemfuensis). Para el manejo rotacional del pasto, el número de cuartones por grupo estuvo entre cuatro y ocho. La aplicación del método de puntero y continuadores posibilitó mayor equilibrio entre la composición y cantidad de pasto y los requerimientos de los animales. Con la utilización de las leguminosas en el sistema, se puede llegar a producciones de 15 kg leche vaca-1 d-1, con mínimo uso de suplemento. La suplementación mostró mayor ventaja cuando el diferencial entre el pasto y el potencial del animal fue más marcado. El efecto del suplemento fue mayor al inicio de la lactación. Los sistemas de alimentación con pastoreo restringido en el período poco lluvioso, complementados con ensilaje o caña de azúcar como forraje, alcanzaron producciones individuales entre 7 y 8 kg de leche d-1, con consumo de complemento entre 5.8 y 7.3 kg MS vaca-1 d-1 para la caña y ensilaje, respectivamente. [ABSTRACT FROM AUTHOR]

The main results obtained in milk production under Cuban conditions, with the grass as basic foods are shown. With the appropriate interaction of stocking rate and grass varieties, dairy productions between 8 and 9 kg d-1 during the rainy season were reached, with stocking rate of 3.0 cows ha-1 in coast cross Bermuda grass (Cynodon dactylon), 4.0 cows ha-1 in pangola grass (Digitaria decumbens Stent) and 5.0 cows ha-1 in star grass (Cynodon nlemfuensis).For the grass rotational management, the number of paddocks per group was between four and eight. The application of the pin pointer method and followers make possible higher balance between the composition and grass quantity and the animals requirements. With the use of legumes in the system, productions of 15 kg milk cow-1 d-1 can reached, with the lower supplement use. The supplementation showed higher advantage when the differential between the grass and the animal potential was more marked. The supplementation effect was higher at the beginning of lactation. The feeding systems with restricted grazing in the dry season, complemented with silage or sugar cane as forage, reached individuals productions between 7 and 8 kg of milk d-1, with complement intake between 5.8 and 7.3 kg DM cow -1 d-1for sugar cane and silage, respectively. [ABSTRACT FROM AUTHOR]

Para evaluar el probiótico Sorbial como aditivo para cabras lecheras en pastoreo de gramíneas en las condiciones del trópico, se evaluaron 180 cabras lecheras (90 Saanen y 90 Alpina), con 41.3 ± 0.4 kg de peso vivo, 23.6 d de lactancia y 2.1 partos como promedio. La duración del estudio fue de 245 d. Las cabras pastaron gramíneas (mezcla de pasto estrella y pasto natural) y se suplementaron con 0.46 kg de concentrado animal-1 d-1. Se distribuyeron aleatoriamente en dos tratamientos: A. 10 g de probiótico en el post-parto, hasta los 100 d de lactancia, y B.0 g de probiótico post-parto. Los resultados de la producción de leche indicaron que las cabras que consumieron el probiótico, en ambas razas, produjeron 3.9 % más de leche (P < 0.05) que las que no lo consumieron. Sin embargo, las cabras Saanen produjeron 2.4 % más de leche (P< 0.05) que las Alpinas. Con la utilización del probiótico, la calidad de la leche mejoró (P < 0.05) en 6.9 y 7.8 % para el porcentaje de grasa y sólidos no grasos. Los costos del litro de leche, por concepto de suplementos, disminuyeron (P < 0.05) en 0.012 y 0.007 pesos cubanos por la inclusión del probiótico, para las razas Saanen y Alpinas respectivamente. En las condiciones de este estudio, la utilización del probiótico durante los primeros 100 d de lactancia, mejoró la producción y calidad láctea, y disminuyó los costos por concepto de suplementos. [ABSTRACT FROM AUTHOR]

To evaluate the Sorbial probiotic as additive for dairy goats in grazing under tropic conditions, 180 dairy goats were evaluated (90 Saanen and 90 Alpina), with 41.3 ? 0.4 kg of live weight, 23.6 days of lactation and 2.1parturition as average. The study lasted 245 days. Goats grazing (start grass and natural grass mixing) and were supplemented with 0.46 kg of concentrate animal-1 d-1. They were randomly distributed in 2 treatments: A.10g of probiotic in post parturition, until 100 days of lactation, and B. 0g of probiotic post parturition probiotic. The results of milk production showed that goats that consumed the probiotic, in both breeds, produced 3.9% more milk (P < 0.05) than those that did not consume it. Although, the Saanen goats produced 2.4% more milk (P < 0.05) than the Alpinas. With the probiotic usage, milk quality improved (P < 0.05) in 6.9 and 7.8% for the fat percentage and non fat solids. The costs of the milk liter, per supplement concepts, decreased (P < 0.05) in 0.012 and 0.007 Cuban pesos due to the probiotic inclusion, for Saanen and Alpine breeds, respectively. In this study conditions, the use of the probiotic during the first 100 lactation days, decreased costs per supplement concepts. [ABSTRACT FROM AUTHOR]

In order to characterize the performance of dairy cows under stabulation conditions, fed integral diets of tropical forages, a study was conducted for three years. The observations were conducted for 72 h consecutively in each season to calculate the times spent in each activity (feed intake, rumination, water ingestion, resting and walking). A linear model of fixed effect was used for the statistical analysis, controlling group, season, year and possible interactions. The times dedicated to consumption were longer (P < 0.01) during the day and in the dry season (369.47, 83.67, 415.55 and 120.40 min, rainy/daytime, rainy /night time, dry season/daytime and dry season/night time, respectively). In rumia, the times increased (P < 0.001) in the dry season and at night (67.35, 271.79, 61.23 and 329.07 min for rainy/daytime, rainy/night time, dry season/daytime and dry season/night time, respectively). The intake rate of the milking cows in both seasons diminished (P < 0.01) in 24.2 and 25.5% in the rainy and dry season, respectively, compared with those that were not lactating. The distribution of the animals' percentage in the intake activity was maintained, approximately, in 90.0% in the rainy season, three hours after the feed supply, and in the dry season during the first five hours. Meanwhile, the animals' percentage in rumination was concentrated between 10.00 p.m. and 3.00 a.m., and was superior to 40%. The study demonstrated that, apart from the management under stabulation conditions, the animals maintained a behavior in accordance with the availability and quality of forages. Besides, it was proved that the feed supply time influences markedly on the intake distribution. [ABSTRACT FROM AUTHOR]

The study was conducted for a year in a dairy unit DESA-120. A total of 45 dairy cows from Siboney breed were used since the beginning of lactation. They were randomly distributed in three treatments of 15 animals each: a) supplementation, with 100 % commercial feedstuff; b) supplementation, with 50 % commercial feedstuff and 50 % Norgold, and c) supplementation, with 100 % Norgold. All the animals grazed together for 16 h daily, in paddocks of pure grasses (Guinea grass and star grass) or in association of grasses and legumes (Guinea grass and leucaena). The results of milk production did not show differences between treatments (14.7, 14.4 and 14.8 kg/cow/d, for 100 % feedstuff, 50 % feedstuff-50 % Norgold and 100 % Norgold, respectively). In respect to milk production per lactation, the animals of first lactation produced less (P < 0.001) than those of the second and third. The analysis of dairy quality showed that the fat percentage of the milk from the animals supplemented with 100 % Norgold was lower (P < 0.01) than the rest of the treatments, that did not differ among them (3.98, 3.99 and 3.73 % for the treatments with 100 % feedstuff, 50 % commercial feedstuff-50 % Norgold and 100 % Norgold, respectively). There were no differences between the other dairy components. The daily intake of supplement per cow did not indicate differences between treatments and was in the order of 4.7 to 4.8 kg of fresh matter/milking cow/d. The cost of the milk liter produced by concept of the supplement indicated that the lowest cost (P < 0.001) was for the milk from the animals supplemented 100 % Norgold (0.09, 0.08 and 0.06 $/L of milk), for the treatments with 100 % feedstuff, 50 % commercial feedstuff-50 % Norgold and 100 % Norgold, respectively. The results of liveweight and of the main reproductive indicators did not show differences between treatments. It is concluded that, under the conditions of this study, the use of Norgold in the supplementation of dairy cows in grazing did not affect milk production, liveweight or reproductive performance. However, the production costs by concept of supplementation decreased between 11.1 and 33.3 %. Further studies with a larger number of animals and longer duration including other measurements such as the general health of the dairy animal are recommended. [ABSTRACT FROM AUTHOR]

El trabajo se desarrolló durante un año en una vaquería DESA-120. Se utilizaron en total 45 vacas lecheras, de la raza Siboney de Cuba, desde el inicio de lactancia. Estas se distribuyeron aleatoriamente en tres tratamientos de 15 animales cada uno: a) suplementación, con 100 % de pienso comercial; b) suplementación, con 50 % de pienso comercial y 50 % de Norgold y c) suplementación, con 100 % de Norgold. Todos los animales pastaron juntos, durante 16 h diarias, en cuartones de gramíneas puras (guinea Likony y pasto estrella) o en asociación de gramíneas y leguminosas (guinea Likony y leucaena). Los resultados de la producción de leche no expresaron diferencias entre los tratamientos (14.7, 14.4 y 14.8 kg/vaca/d, para 100 % de pienso, 50 % de pienso - 50 % de Norgold y 100 % Norgold, respectivamente). Con respecto a la producción de leche por lactancia, los animales de primera lactancia produjeron menos (P < 0.001) que los de la segunda y tercera. Los análisis de la calidad láctea demostraron que el porcentaje de grasa de la leche de los animales suplementados con 100 % de Norgold fue menor (P < 0.01) que el del resto de los animales, que no difirieron entre sí (3.98, 3.99 y 3.73 % para los tratamientos con 100 % de pienso, 50 % de pienso comercial y 50 % de Norgold y 100 % Norgold, respectivamente). No hubo diferencias entre los demás componentes lácteos. El consumo diario de suplemento por vaca no indicó diferencias entre los tratamientos y estuvo en el orden de 4.7 a 4.8 kg de materia fresca/vaca en ordeño/d. El costo del litro de leche producido por concepto del suplemento indicó que el menor costo (P < 0.001) fue para la leche de los animales suplementados con 100 % de Norgold (0.09, 0.08 y 0.06 $/L de leche), para los tratamientos con 100 % de pienso, 50 % de pienso comercial y 50 % de Norgold, respectivamente. Los resultados del peso vivo y de los principales indicadores reproductivos no presentaron diferencias entre los tratamientos. Se concluye que, en las condiciones de este estudio, la utilización de Norgold en la suplementación a vacas lecheras en pastoreo no afectó la producción de leche, el peso vivo ni el comportamiento reproductivo. Sin embargo, disminuyeron los costos de producción por concepto de suplementación, entre 11.1 y 33.3 %. Se recomiendan estudios con mayor número de animales y duración, en los que se contemplen otras mediciones como la salud general del animal lechero. [ABSTRACT FROM AUTHOR]

The article presents a study which characterized the animal behavior at different grazing intensities. The materials and methods used are described, as well as the time distribution of the activities related to the intake of the grazing animals. According to the authors, the availability and quality of the pasture had great influence on the animal behavior during grazing.

The article provides information on a study which assessed the balance of nitrogen (N), phosphorous (P) and potassium (K) in a dairy unity, established with star grass. Used in the study were a completely randomized design with four repetitions on a red ferralic soil and two grazing methods with 9 hectares each and commercial Holstein cows. Mathematical analysis was also used according to a simple classification model.

The article presents a four-year study which evaluated the economical effect of two grazing intensities in a soil-plant-animal system in Cuba. Expenses and incomes were taken by the grazing method in the economical analysis. The benefit-cost radio did not show any difference between the methods used, and the economical gains per animal per area did not differ between treatments. The results indicated that there is an unsustainability in the systems during the four years.

Sixty crossbred heifers (371 ± 7 kg) were used in a 63-d feeding trial (4 pens per treatment in a randomized complete block design) to evaluate the influence of dietary supplementation with zilpaterol hydrochloride (β-agonist) or with different levels of chromium-enriched live yeast (Cr-YC) on growth performance and carcass characteristics. Heifers were fed a diet based on steam-flaked corn (1.45 Mcal of net energy of gain, NEg kg-1). Treatments were: 1) control, no yeast, no zilpaterol supplementation (Ctrl); treatments 2, 3 and 4) were the same basal diet supplemented with a commercial Cr-YC for a final dose of 10, 20 or 30 g hd-1 d-1 of yeast strain, and 5) the same basal diet (Ctrl) supplemented with 6 mg of zilpaterol kg-1 of feed for 30 d (ZIL), drug withdrawn from the diet 3 d pre-harvest. Compared with controls, ZIL increased final weight (3.8 %, P < 0.03), carcass-adjusted daily gain (18.7 %, P = 0.05), apparent dietary net energy of maintenance (14 %, P < 0.01), and decreased observed/expected DMI (14 %, P < 0.01). Treatment with ZIL did not affect (P < 0.13) marbling score, but, compared with control group, increased carcass dressing percentage (2.6 %, P = 0.01), and reduced (P = 0.02) kidney, pelvic and heart fat (KPH, 19.8 %) and fat thickness (9.4 %) and tended (5.9 %, P = 0.06) to increase Longissimus muscle area. Compared with Cr-YC treatments, ZIL increased apparent dietary NEm (P = 0.03) and dressing percentage (P < 0.01), and decreased observed/expected DMI (P = 0.03) and KPH (P=0.04). Treatment with Cr-YC did not affect carcass characteristics, but compared with control, Cr-YC supplementation tended to increase final BW (P = 0.08), ADG (0.09), fed:gain ratio (F:G, P = 0.08) and dietary NE (P = 0.06). Level of supplemental Cr-YC increased (linear component, P ≤ 0.04) final BW, ADG, F:G, apparent dietary NEm, and decreased (P = 0.02) observed/expected DMI. Level of supplemental Cr-YC did not affect (P ≥ 0.33) dressing percentage, LM area or marbling score, but, fat thickness and KPH decreased (P = 0.02) as Cr-YC level supplementation increase. DMI and HCW tended (P ≤ 0.08) to increase with increasing Cr-YC supplementation level. It is concluded that, zilpaterol supplementation increase growth performance in heifers as results of greater muscle accretion and for reduction of body fat. Chromium-enriched yeast supplementation increase growth performance and dietary NE, with modest effect in carcass characteristics. Better responses were observed at level of Cr-YC supplementation of 30 g hd-1 d-1 that corresponds to daily intakes of 1.65 x 1011 colony forming units and 15 mg chromium. [ABSTRACT FROM AUTHOR]

Our aim was to evaluate neurosensory symptoms after lateralisation of the inferior alveolar nerve (IAN). We studied a retrospective case series with one-year follow up that included 139 procedures in 123 patients. After the IAN had been located it was deflected from the mandibular body and the implant placed. Sensitivity was mapped 24hours, one month, six months, and one year after the intervention by gently pressing the skin and lips with the tip of a probe. A total of 337 implants were placed in 123 patients aged between 44 and 68 years. There were 33 men and 90 women and they all recovered. The IAN was mobilised by one of two procedures, one that involves the nerve directly (transposition) and one that does not (lateralisation). During lateralisation the nerve is deflected laterally through a mandibular osteotomy, while the mental nerve and mental foramen are not manipulated. The resulting hypoaesthetic area was drawn on a graph to assess its extension. Although different techniques are available for placing implants in atrophic jaws, mobilisation of the IAN is indicated in certain cases in which other techniques are not feasible or have a high risk of complications., (Copyright © 2019 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The aim of the present study was to determine the role of the catechol group in the antioxidant and neuroprotective effects of minor components of virgin olive oil in rat brain tissue. Hydroxytyrosol ethyl ether (HT, 2 OH), tyrosol ethyl ether (Ty, 1 OH) and 3,4-di-ortho-methylidene-hydroxytyrosol ethyl ether (MET, no OH) were compared. Oxidative stress was induced with ferrous salts (lipid peroxidation induction), diethylmaleate (depletion of glutathione) and hypoxia-reoxygenation in brain slices. Lipid peroxidation was inhibited in direct proportion to the number of OH groups: HT>Ty>MET. Exposure to HT led to partial recovery of the glutathione system after chemical inhibition or hypoxia-reoxygenation. All three compounds inhibited cell death in hypoxia-reoxygenation experiments (HT≥Ty>MET). Peroxynitrite formation (3-nitrotyrosine) and inflammatory mediators (prostaglandin E2 and interleukin 1ß) were inhibited by all three compounds. In conclusion, the presence of OH groups in the molecule of these phenolic compounds from virgin olive oil is a determinant factor in their antioxidant effect in brain tissue, but this antioxidant effect is not the only explanation for their neuroprotective effect., (Copyright © 2015. Published by Elsevier Inc.)

We studied 10 minutes segments of heartbeat interval fluctuations from 18 young women in labor with normal outcome of pregnancy. Data of each studied case were classified into two distinct groups. One group involving segments where the uterine activity was observable (three or more contractions in ten minutes), and the other group of reference having segments with fewer uterine activity or not presenting contractions at all. For comparison, we also included segments collected during the last trimester of gestation prior to labor from a third group of women. Corresponding RR interval series were analyzed to estimate RR(mean), RMSSD, α(1), α(1(MAG)) and α(1(SIGN)) parameters. No significant differences among groups were identified in RMSSD, α(1) and α(1(MAG)) Nevertheless, α(1(SIGN)) did present significant differences in comparison with the last trimester results (p<0.007), revealing a subtle change in the temporal organization of maternal RR series during labor. Results of these parameters then suggest that during labor, despite preserving a concomitant non-linear influence, the maternal short-term autonomic cardiac regulation behaves with less antagonism.

Histologically, Kikuchi-Fujimoto disease (KFD) is a necrotising, self-limiting lymphadenitis. It typically affects the lymph nodes of the neck and it is often accompanied by a high fever. The present paper documents the case of a 28-year old male carrier of KFD. From the x-ray images, the KFD clinically appeared to be a submandibular salivary gland tumor. An ultrasound study led us to believe that it was more likely a branchial cyst. Malignant lymphoma can be mistaken for KFD, thus the diagnosis must be precise and the differentiation is crucial.

Report case of a Wunderlich syndrome due to spontaneous rupture of a simple renal cyst. The patient is a 77-year old, hypertensive female who was on routine treatment with Aspirin. The rarity of retroperitoneal haemorrhage with this origin is documented; also the influence of aspirin as predisposing factor for this condition is ruled out. Brief evaluation of the various diagnostic means available. An accurate evaluation that may allow to adopt a conservative aptitude is recommended.

The Southington, Connecticut, water-supply system is characterized by a distribution network that contains more than 1 700 pipeline segments of varying diameters and construction materials, more than 186 mi (299 km) of pipe, 9 groundwater extraction wells capable of pumping more than 4 700 gal/min (0.2965 m3/s), and 3 municipal reservoirs. Volatile organic compounds, which contaminated the underlying groundwater reservoir during the 1970s, contaminated the water-supply system and exposed the town's residents to volatile organic chemicals. We applied a computational model to the water-supply system to characterize and quantify the distribution of volatile organic compounds in the pipelines, from which we estimated the demographic distribution of potential exposure to the town's residents. Based on results from modeling analyses, we concluded the following: (a) exposure to volatile organic compound contamination may vary significantly from one census block to another, even when these census blocks are adjacent to each other within a specified radius; (b) maximum spatial spread of contamination in a water-distribution system may not occur under peak demand conditions, and, therefore, maximum spatial distribution of the exposed population also may not correspond to peak demand conditions, and (c) use of the proposed computational model allows for a more refined and rigorous methodology with which to estimate census-block-level contamination for exposure assessment and epidemiologic investigations.