Study of the effect of clay particles on low salinity water injection in sandstone reservoirs

The need for optimal recovery of crude oil from sandstone and carbonate reservoirs around the world has never been greater for the petroleum industry. Water-flooding has been applied to the supplement primary depletion process or as a separate secondary recovery method. Low salinity water injection is a relatively new method that involves injecting low salinity brines at high pressure similar to conventional water-flooding techniques, in order to recover crude oil. The effectiveness of low salinity water injection in sandstone reservoirs depends on a number of parameters such as reservoir temperature, pressure, type of clay particle and salinity of injected brine. Clay particles present on reservoir rock surfaces adsorb polar components of oil and modify wettability of sandstone rocks to the oil-wet state, which is accountable for the reduced recovery rates by conventional water-flooding. The extent of wettability alteration caused by three low salinity brines on oil-wet sandstone samples containing varying clay content (15% or 30%) and type of clay (kaolinite/montmorillonite) were analyzed in the laboratory experiment. Contact angles of mica powder and clay mixture (kaolinite/montmorillonite) modified with crude oil were measured before and after injection with three low salinity sodium chloride brines. The effect of temperature was also analyzed for each sample. The results of the experiment indicate that samples with kaolinite clay tend to produce higher contact angles than samples with montmorillonite clay when modified with crude oil. The highest degree or extent of wettability alteration from oil-wet to intermediate-wet state upon injection with low salinity brines was observed for samples injected with brine having salinity concentration of 2000 ppm. The increase in temperature tends to produce contact angles values lying in the higher end of the intermediate-wet range (75°–115°) for samples treated at 50 °C, while their corresponding samples treated at 25 °C produced contact angle values lying in the lower end of intermediate-wet range

"Do this! Do that!, And Nothing will happen":Do specifications lead to securely stored passwords?

Does the act of writing a specification (how the code should behave) for a piece of security sensitive code lead to developers producing more secure code? We asked 138 developers to write a snippet of code to store a password: Half of them were asked to write down a specification of how the code should behave before writing the program, the other half were asked to write the code but without being prompted to write a specification first. We find that explicitly prompting developers to write a specification has a small positive effect on the security of password storage approaches implemented. However, developers often fail to store passwords securely, despite claiming to be confident and knowledgeable in their approaches, and despite considering an appropriate range of threats. We find a need for developer-centered usable mechanisms for telling developers how to store passwords: lists of what they must do are not working

Demarcating Geographic Regions using Community Detection in Commuting Networks with Significant Self-Loops

We develop a method to identify statistically significant communities in a weighted network with a high proportion of self-looping weights. We use this method to find overlapping agglomerations of U.S. counties by representing inter-county commuting as a weighted network. We identify three types of communities; non-nodal, nodal and monads, which correspond to different types of regions. The results suggest that traditional regional delineations that rely on ad hoc thresholds do not account for important and pervasive connections that extend far beyond expected metropolitan boundaries or megaregions.Comment: 38 page

Effect of Surgical Fusion on Volitional Weight-Shifting in Individuals With Adolescent Idiopathic Scoliosis

Study Design Prospective. Objectives The goals of this study were to (1) evaluate the differences in weightbearing symmetry between individuals with adolescent idiopathic scoliosis (AIS) and typically developing controls; (2) observe the effect of posterior spinal fusion and instrumentation (PSFI) on volitional weight-shifting at 1 and 2 years postoperatively; and (3) evaluate whether lowest instrumented fusion level (ie, lowest instrumented vertebra [LIV]) in PSFI has an effect on volitional weight-shifting. Summary of Background Data Previous studies have conflicting findings with regard to the effect of scoliosis on postural control tasks as well as the effect of surgery. They have also noted an inconsistent effect of PSFI at different LIVs, with more distal LIVs exhibiting greater reductions in postoperative range of motion. Methods The study was designed with an AIS group of 41 patients (8 males and 33 females) with AIS who underwent PSFI, along with a Control Group of 24 age-matched typically developing participants (12 male and 12 female). Both groups performed postural control tasks (static balance and volitional weight-shifting), with the AIS group repeating the tasks at 1 and 2 years postoperatively. Results At baseline, the AIS group showed increased weightbearing asymmetry than the Control Group (p = .01). The AIS group showed improvements in volitional weight-shifting at 2 years over baseline (p \u3c .01). There was no effect of LIV on volitional weight-shifting by the second postoperative year. Conclusions Individuals with AIS have greater weightbearing asymmetry but improved volitional weight-shifting over typically developing controls. PSFI improves volitional weight-shifting beyond preoperative baseline but does not differ significantly by LIV

Effect of Surgical Fusion on Volitional Weight-Shifting in Individuals With Adolescent Idiopathic Scoliosis

Study Design Prospective. Objectives The goals of this study were to (1) evaluate the differences in weightbearing symmetry between individuals with adolescent idiopathic scoliosis (AIS) and typically developing controls; (2) observe the effect of posterior spinal fusion and instrumentation (PSFI) on volitional weight-shifting at 1 and 2 years postoperatively; and (3) evaluate whether lowest instrumented fusion level (ie, lowest instrumented vertebra [LIV]) in PSFI has an effect on volitional weight-shifting. Summary of Background Data Previous studies have conflicting findings with regard to the effect of scoliosis on postural control tasks as well as the effect of surgery. They have also noted an inconsistent effect of PSFI at different LIVs, with more distal LIVs exhibiting greater reductions in postoperative range of motion. Methods The study was designed with an AIS group of 41 patients (8 males and 33 females) with AIS who underwent PSFI, along with a Control Group of 24 age-matched typically developing participants (12 male and 12 female). Both groups performed postural control tasks (static balance and volitional weight-shifting), with the AIS group repeating the tasks at 1 and 2 years postoperatively. Results At baseline, the AIS group showed increased weightbearing asymmetry than the Control Group (p = .01). The AIS group showed improvements in volitional weight-shifting at 2 years over baseline (p \u3c .01). There was no effect of LIV on volitional weight-shifting by the second postoperative year. Conclusions Individuals with AIS have greater weightbearing asymmetry but improved volitional weight-shifting over typically developing controls. PSFI improves volitional weight-shifting beyond preoperative baseline but does not differ significantly by LIV

Subtypes of Intellectual Disability in School-Aged Children

Purpose: To explore the presence of subtypes of intellectual functioning in children with mild intellectual disability (ID) and to externally validate the subtypes on measures of academic, adaptive and psychosocial functioning. Method: Participants were 167 children age 6-16 years with a mild ID. All children completed the WISC-III, WIAT, VABS, and PIC-R. Results: Based on a two-stage cluster analysis on the four WISC-III Index scores four subtypes emerged reflecting distinct profiles: (1) language-strength subtype; (2) nonverbal strength subtype; (3) symbol-processing strength subtype; and (4) global deficits subtype. The subtypes were externally validated on tests of academic achievement, adaptive functioning, and psychosocial functioning. Conclusions: Rather than only demonstrating a global or “flat" pattern of cognitive deficits, the findings suggest that children with mild ID have certain profiles of intellectual functioning that are similar to those seen in normal children and children with learning disabilities