Modeling river delta formation

A new model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/ erosion law. Different delta types are reproduced using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore our model is capable to simulate the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi river

Non-Newtonian fluid flow through three-dimensional disordered porous media

We investigate the flow of various non-Newtonian fluids through three-dimensional disordered porous media by direct numerical simulation of momentum transport and continuity equations. Remarkably, our results for power-law (PL) fluids indicate that the flow, when quantified in terms of a properly modified permeability-like index and Reynolds number, can be successfully described by a single (universal) curve over a broad range of Reynolds conditions and power-law exponents. We also study the flow behavior of Bingham fluids described in terms of the Herschel-Bulkley model. In this case, our simulations reveal that the interplay of ({\it i}) the disordered geometry of the pore space, ({\it ii}) the fluid rheological properties, and ({\it iii}) the inertial effects on the flow is responsible for a substantial enhancement of the macroscopic hydraulic conductance of the system at intermediate Reynolds conditions. This anomalous condition of ``enhanced transport'' represents a novel feature for flow in porous materials.Comment: 5 pages, 5 figures. This article appears also in Physical Review Letters 103 194502 (2009

Medium‐grade proteinuria is a risk factor for incident markers of chronic kidney disease

Objective Medium‐grade proteinuria (100–500 mg/g creatinine) is common among people living with HIV/AIDS (PLWHA) but is often undetected or ignored. This prospective, observational cohort study examined medium‐grade proteinuria as a risk factor for markers of chronic kidney disease (CKD). Methods Quantitative urine samples were collected from 241 PLWHA without known renal disease at baseline between January 2009 and February 2011 and at follow‐up 240 weeks later. Multivariate analysis was performed to assess medium‐grade proteinuria as a risk factor for incident markers of CKD (estimated glomerular filtration rate < 60 mL/min/1.73 m2, albuminuria, phosphaturia). Results Incident markers of CKD were identified in 33 patients (14%), of whom 24 (74%) had medium‐grade proteinuria at baseline. Of these, 22 even had proteinuria of < 200 mg/g creatinine. Multivariate analysis showed an adjusted relative risk (aRR) of 2.4 for patients with baseline medium‐grade proteinuria to develop signs of CKD. Age was identified as an additional independent predictor. By testing for interaction, tenofovir disoproxil fumarate (TDF)‐independent proteinuria was strongly associated with incident CKD markers (aRR = 12.1). Conclusion Medium‐grade proteinuria of 100–500 mg/g creatinine is both frequent in PLWHA and a significant risk factor for developing markers of CKD, especially in the absence of TDF. Relevant risk seems to be associated with proteinuria levels as low as 100–200 mg/g creatinine. Current guidelines recommend specific action for proteinuria exceeding 135–200 mg/g but still will miss a relevant number of PLWHA potentially at risk for CKD. An even lower cut‐off to trigger nephrological work‐up and potentially renoprotective interventions appears to be indicated

First trimester fetal heart rate as a predictor of newborn sex

OBJECTIVE: To predict the sex of newborns using first trimester fetal heart rate (FHR). METHODS: This was a retrospective review of medical records and ultrasounds performed between 8 and 13 weeks of gestation. Continuous variables were compared using Student\u27s t-tests while categorical variables were compared using Chi-square test. RESULTS: We found no significant differences between 332 (50.7%) female and 323 (49.3%) male FHRs during the first trimester. The mean FHR for female fetuses was 167.0 +/- 9.1 bpm and for male fetuses 167.3 +/- 10.1 bpm (p = 0.62). There was no significant difference in crown rump length between female and male fetuses (4.01 +/- 1.7 versus 3.98 +/- 1.7 cm; p = 0.78) or in gestational age at birth (38.01 +/- 2.1 versus 38.08 +/- 2.1 weeks; p = 0.67). The males were significantly heavier than females (3305.3 +/- 568.3 versus 3127.5 +/- 579.8 g; p \u3c 0.0001) but there were no differences in the proportion of small for gestational age (SGA), average for gestational age (AGA) and large for gestational age (LGA) infants. CONCLUSIONS: We found no significant difference between the female and male FHR during the first trimester in contrast to the prevailing lay view of females having a faster FHR. The only statistically significant difference was that males weighed more than female newborns

LOSS OF PHOSPHORUS BY RUNOFF FOR AGRICULTURAL WATERSHEDS

The loss of nutrients in runoff from agricultural land is a major cause of poor surface water quality in the United State. Scientists (NRCS) developed a technique to estimate the impact of agricultural watersheds on natural water resources. The objectives of this study were to apply this technique on the Wagon Train (WT),watershed to predict (1) loss of water by surface runoff, (2) loss of phosphorus (P) from soils by runoff and P loading for WT reservoir. The annual loss of water by runoff was estimated at 4.32 million m3 . The USGS data for a 50-year period (1951 to 2000) indicated that the average annual inflow for WT reservoir was 4.25 million m3 . The predicted annual P loss by runoff was 844 kg and could be considered as the annual loading for WT reservoir. The predicted P concentration in the runoff water at field sites was 196 μg/L. Phosphorus concentration observed in major streams at the beginning of spring (March) ranged from 99 μg/L to 240 μg/L with an average of 162 μg/L (S.D..= 40 μg/L), and the average P concentration in water samples taken from different locations in the reservoir was 140 μg/L. Phosphorus uptake by algae, weeds and aquatic plants, as well as high pH in the reservoir and streams might explain the slight drop of P concentration in waters. Further, the average P concentration observed in the main stream samples for the entire rainy season (March through October), ranged between 157 and 346 μg/L with an average of 267 μg/L (S.D. = 65 μg/L). Application of P fertilizers (April/May) for summer crops might explain the increase in P concentration. When factors affecting P concentration in streams are considered, the technique could provide a reasonable estimation of P concentration in stream water