Simultaneous counter-flow of chlorinated volatile organic compounds across the saturated-unsaturated interface region of an aquifer

Concentrations of chlorinated volatile organic compounds (Cl-VOCs) at the saturated-unsaturated interface region (SUIR; depth of ∼18 m) of a sandy phreatic aquifer were measured in two monitoring wells located 25 m apart. The concentrations of the Cl-VOCs obtained above and below the water table along a 413-day period are interpreted to depict variable, simultaneous and independent movement of trichlorothene, tetrachloroethene, 1,1-dichloroethene, cis-1,2-dichloroethene, 1,1,1-trichloroethane, chloroform and 1,1-dichloroethane vapors in opposite directions across the SUIR.     

Impact of ZnO embedded feed spacer on biofilm development in membrane systems

The concept of suppressing biofouling formation using an antibacterial feed spacer was investigated in a bench scale-cross flow system mimicking a spiral wound membrane configuration. An antibacterial composite spacer containing zinc oxide-nanoparticles was constructed by modification of a commercial polypropylene feed spacer using sonochemical deposition. The ability of the modified spacers to repress biofilm development on membranes was evaluated in flow-through cells simulating the flow conditions in commercial spiral wound modules. The experiments were performed at laminar flow (Re = 300) with a 200 kDa molecular weight cut off polysulfone ultrafiltration membrane using Pseudomonas putida S-12 as model biofilm bacteria. The modified spacers reduced permeate flux decrease at least by 50% compared to the unmodified spacers (control). The physical properties of the modified spacer and biofilm development were evaluated using high resolution/energy dispersive spectrometry-scanning electron microscopy, atomic force microscopy and confocal laser scanning microscopy imaging (HRSEM, EDS, AFM and CLSM). HRSEM images depicted significantly less bacteria attached to the membranes exposed to the modified spacer, mainly scattered and in a sporadic monolayer structure. AFM analysis indicated the influence of the modification on the spacer surface including a phase change on the upper surface. Dead-live staining assay by CLSM indicated that most of the bacterial cells attached on the membranes exposed to the modified spacer were dead in contrast to a developed biofilm which was predominant in the control samples.     

An information entropy approach to the small-lot concept

Just-in-time and total quality management advocate the use of small lots in production, as they yield higher throughput, better quality, lower response time, less operating expenses, better due date performance, and less work in process. Implementation of the small-lot concept is often resisted by MIS managers and production people who feel that the larger number of lots-the apparently inevitable result of reducing lot size, will entail more information and stronger information technology. By developing a normative model, based on the entropy measurement, this paper claims that the move towards smaller lots implies less information needs. Theorems concerning the relationship between quantity of information and lot size are proved, showing that the new directions that manufacturing is taking entail less information needs     

does intravenous administration of human albumin prevent severe ovarian hyperstimulation syndrome?

OBJECTIVE: To report our experience with i.v. albumin as a means to prevent ovarian hyperstimulation syndrome (OHSS) in high-risk patients. DESIGN: Retrospective case-series. SETTING: University hospital-based IVF program. PATIENTS: Five women undergoing controlled ovarian stimulation for IVF-Based on previous history and/or E2 measurements and number of ovarian follicles, these patients were considered to be at high risk for developing OHSS. INTERVENTIONS: Intravenous albumin was given at the time of oocyte retrieval. Additional doses were given 12 and 24 hours later. MAIN OUTCOME MEASURE: Development of OHSS. RESULTS: Four patients developed OHSS; two of them had the severe form of the syndrome. CONCLUSIONS: Severe OHSS may develop in high-risk patients despite the prophylactic administration of i.v. albumin.     

Imaging H2(17)O distribution in a phantom and measurement of metabolically produced H2(17)O in live mice by proton NMR

Previously we suggested a method for indirect detection of H2(17)O via a combination of 1H spin-echo sequence and 17O decoupling. The method is based on the shortening of the water proton T2 due to the residual spin-spin coupling with the 17O nucleus, and on our finding that this shortening is abolished by applying an radio frequency field at the 17O resonance frequency. In the present work we demonstrate how the method can be used for imaging low concentrations of H2(17)O, and report for the first time an application of this method to in vivo detection of H2(17)O in live newborn mice, where the H2(17)O was introduced either directly i.p. or by inhalation of 17O2 where it was formed by oxidative metabolic activity.     

Usage and perceived effectiveness of fatigue countermeasures for professional and nonprofessional drivers

BackgroundDrivers adopt various strategies in order to cope with fatigue and falling asleep at the wheel. These strategies include a wide range of activities that may invigorate the body and/or the mind.ObjectivesTo compare usage patterns and to evaluate the perceived effectiveness of different coping behaviors adopted by professional and nonprofessional drivers in order to maintain alertness.MethodThe study was conducted using a large-scale survey, filled by 100 professional and 90 nonprofessional drivers.ResultsListening to the radio and opening the window were the most frequently used and also perceived as highly effective coping behaviors by both groups of drivers. Talking on a cellular phone or with a passenger were more frequently used by nonprofessional drivers whereas, planning rest stops ahead, stopping for a short nap and drinking coffee were more frequently used by professional drivers. These methods were also perceived as more effective by professional than by the nonprofessional drivers and their usage frequency highly correlated with their perceived effectiveness.ConclusionsNonprofessional drivers counteract fatigue only at the tactical/maneuvering level of the drive. Hence, they tend to adopt methods that help them pass the time and reduce their feeling of boredom but do not require advance preparations or adjustments in the driving. In contrast, professional drivers counteract fatigue also at the strategic/planning level of driving, and use a much larger repertoire of coping-behaviors.ImplicationsFatigue countermeasures should include all levels of the driving task hierarchy, and experience-based countermeasures used by professional drivers should be considered for experimental validation.     

Weak Derandomization of Weak Algorithms: Explicit Versions of Yao��s Lemma

A simple averaging argument shows that given a randomized algorithm A and a function f such that for every input x, Pr[A(x) = f(x)] ≥ 1 − ρ (where the probability is over the coin tosses of A), there exists a non-uniform deterministic algorithm B “of roughly the same complexity” such that Pr[B(x) = f(x)] ≥ 1 − ρ (where the probability is over a uniformly chosen input x). This implication is often referred to as “the easy direction of Yao’s lemma” and can be thought of as “weak derandomization” in the sense that B is deterministic but only succeeds on most inputs. The implication follows as there exists a fixed value r′ for the random coins of A such that “hardwiring r′ into A” produces a deterministic algorithm B. However, this argument does not give a way to explicitly construct B.