Comparison of Saturated Hydraulic Conductivity Measurement Methods for a Glacial-Till Soil

Hydraulic conductivity is the single most important hydraulic parameter for flow and transport-related phenomena in soil, but the results from different measuring methods vary under different field conditions. To evaluate the performance of four in situ saturated hydraulic conductivity (Ks) measuring methods, Ks measurements were made at four depths (15, 30, 60, and 90 cm) and five locations on a glacial-till soil of Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll)-Clarion (fine-loamy, mixed, mesic Typic Hapludoll) association. The four in situ methods were: (i) Guelph permeameter, (ii) velocity permeameter, (iii) disk permeameter, and (iv) double-tube method. The Ks was also determined in the laboratory on undisturbed soil cores collected from all the five sites and four depths. The Guelph permeameter method gave the lowest Ks values, possibly because of small sample size, whereas the disk permeameter and double-tube methods gave maximum values for Ks with minimum variability, possibly because of large sample size. Maximum variability in Ks values for soil cores at shallow depths may have occurred because of the presence or absence of open-ended macropores. Estimates of Ks, however, are most comparable for the velocity permeameter and the laboratory method using a constant-head permeameter

The Wnt/β-catenin pathway regulates growth and maintenance of colonospheres

<p>Abstract</p> <p>Background</p> <p>Recent evidence suggests that epithelial cancers, including colorectal cancer are driven by a small sub-population of self-renewing, multi-potent cells termed cancer stem cells (CSCs) which are thought to be responsible for recurrence of cancer. One of the characteristics of CSCs is their ability to form floating spheroids under anchorage-independent conditions in a serum-free defined media. The current investigation was undertaken to examine the role of Wnt/β-catenin pathway in regulating the growth and maintenance of colonospheres. Human colon cancer cells HCT-116 (p53 wild type; <it>K-ras </it>mutant), HCT-116 (p53 null; <it>K-ras </it>mutant) and HT-29 (p53 mutant) were used.</p> <p>Results</p> <p>Colonospheres formed <it>in vitro </it>exhibited higher expression of colon CSCs markers LGR5, CD44, CD166 and Musashi-1 along with putative CSC marker EpCAM, compared to the corresponding parental cancer cells and also exhibit the ability to form spheroids under extreme limiting dilution, indicating the predominance of CSCs in colonospheres. Colonospheres formed by HCT-116 cells show over 80% of the cells to be CD44 positive, compared to ≤ 1% in the corresponding parental cells. Additionally, colonospheres showed reduced membrane bound β-catenin but had increased levels of total β-catenin, cyclin-D1 and c-myc and down regulation of axin-1 and phosphorylated β-catenin. Increased expression of β-catenin was associated with a marked transcriptional activation of TCF/LEF. The latter was greatly decreased following down regulation of β-catenin by the corresponding siRNA, leading to a marked reduction in CD44 positive cells as well as colonospheres formation. In contrast, upregulation of c-myc, a down-stream effector of TCF/LEF greatly augmented the formation of colonospheres.</p> <p>Conclusion</p> <p>Our data suggest that colonospheres formed by colon cancer cell lines are highly enriched in CSCs and that Wnt/β-catenin pathway plays a critical role in growth and maintenance of colonospheres.</p

Temporal Dynamics of Preferential Flow to a Field Tile

We conducted a sequential tracer leaching study on a field plot to investigate the temporal behavior of preferential flow to a field tile during an irrigation and subsequent rainfall events over a 14-d period. Two herbicides, along with the conservative tracer Br, were applied to a strip adjacent to a tile drain immediately before a 4.2-mm hr-1 irrigation. Three additional conservative fluoridated benzoates (PF, TF, and PF) were applied to the strip at 2-hr intervals during the irrigation. Breakthrough of the conservative tracer Br and the two herbicides occurred within the first 2-hr of irrigation, indicating that a small fraction of the solute moved through preferential flow paths. The last tracer (PF), applied 6 hr after the start of irrigation, took only 15 min and 1 mm of irrigation water to travel the 1.2-m distance between the soil surface and the tile. Thus, flow along preferential flow paths was faster during later stages of the irrigation. This study demonstrates that solute transport rates in preferential flow pathways is not a constant during a leaching event

To study the incidence of retinopathy of prematurity in high-risk neonates and the risk factors associated with the disease

Background: Retinopathy of prematurity (ROP) is a complex disease of the developing retinal vasculature in premature infant. The challenge in India is that a large number of neonatal intensive care units (NICUs) don’t have an effective ROP screening strategy. Objective: To measure the incidence of ROP in neonates with gestational age (≤32 weeks) or weighing &lt;2000 g with risk factors and evaluation of risk factor associated with ROP. Materials and Methods: This prospective study was conducted in the Department of Pediatrics and Ophthalmology from January to July 2016. Neonates with gestational age ≤32 weeks, birth weight (BW) ≤1500 g, and selected preterm infants with a BW between 1501 and 2000 g with risk factors admitted in NICU/special new-born care unit were included in the study and screened for ROP by trained ophthalmologist under supervision of the pediatrician. All data were analyzed using SPSS or MedCalc. Univariate and multivariate logistic regression was done to determine the risk factors for the development of any ROP. Result: The incidence of ROP in our study was 19%. 4% of the neonates have severe (early treatment for ROP [ETROP] Type 1) ROP while 15% have non-severe (ETROP Type 2) ROP. 8 neonates developed Stage 1 ROP (42.11%), 7 developed Stage 2 (36.84%), and 4 neonates developed Stage 3 ROP (21.05%). Conclusion: The current study revealed that the incidence of ROP in sick neonates was 19%. Significant risk factors were found to be low BW, low gestational age, supplemental oxygen, and mechanical ventilation, culture proven sepsis, anemia, apnea, and respiratory distress syndrome (RDS)

Preferential Flow Effects on NO3-N Losses with Tile Flow

The variation in continuity and geometry of macropores over the growing season can affect subsurface drain ‘tile’ water and nitrate-nitrogen (NO3-N) concentrations in tile water. This study analyzes the patterns of tile flows and nitrate-nitrogen (NO3-N) concentrations in tile water in relation to rainfall events using field measured data as well as invoking the macropore option of the Root Zone Water Quality Model (RZWQM98). The increase in NO3-N concentration in tile flow during the growing season in comparison with the decrease in NO3-N concentrations after the crop harvest following heavy rainfalls support the role of dual flow theory, soil matrix flow and preferential flow. These results and model simulations suggest that variation in macropore during the growing season can have significant effect on tile flow and NO3-N concentrations in tile water for soils similar to the study area