Phase diagram of the three-dimensional Anderson model of localization with random hopping

We examine the localization properties of the three-dimensional (3D) Anderson Hamiltonian with off-diagonal disorder using the transfer-matrix method (TMM) and finite-size scaling (FSS). The nearest-neighbor hopping elements are chosen randomly according to $t_{ij} \in [c-1/2, c + 1/2]$. We find that the off-diagonal disorder is not strong enough to localize all states in the spectrum in contradistinction to the usual case of diagonal disorder. Thus for any off-diagonal disorder, there exist extended states and, consequently, the TMM converges very slowly. From the TMM results we compute critical exponents of the metal-insulator transitions (MIT), the mobility edge $E_c$, and study the energy-disorder phase diagram.Comment: 4 pages, 5 EPS figures, uses annalen.cls style [included]; presented at Localization 1999, to appear in Annalen der Physik [supplement

Earnings of Black and White Youth and Their Relation to Poverty

This paper examines the relation between youth employment and poverty for black and white families. An increase in the employment proportions of black men ages 16–19, which have lagged far behind their white counterparts, would reduce poverty among blacks to a moderate but meaningful degree. We provide evidence of a small positive feedback relation between black youth employment and family incomes that would magnify gains in both variables if either variable were increased. We also provide evidence that improvements in labor market conditions that affect youth employment, in the educational attainments of black youth, and in other policy-related variables would raise both youth employment and their family incomes.

Do We See Eye to Eye? Moderators of Correspondence Between Student and Faculty Evaluations of Day-to-Day Teaching

Students and instructors show moderate levels of agreement about the quality of day-to-day teaching. In the present study, we replicated and extended this finding by asking how correspondence between student and instructor ratings is moderated by time of semester and student demographic variables. Participants included 137 students and 5 instructors. On 10 separate days, students and instructors rated teaching effectiveness and challenge level of the material. Multilevel modeling indicated that student and instructor ratings of teaching effectiveness converged overall, but more advanced students and Caucasian students converged more closely with instructors. Student and instructor ratings of challenge converged early but diverged later in the semester. These results extend our knowledge about the connection between student and faculty judgments of teaching

Proposal for a Universal Particle Detector Experiment

The Universal Particle Detector Experiment (UPDE), which consists of parallel planes of two diode laser beams of different wavelengths and a large surface metal oxide semiconductor (MOS) impact detector, is proposed. It will be used to perform real-time monitoring of contamination particles and meteoroids impacting the spacecraft surface with high resolution of time, position, direction, and velocity. The UPDE will discriminate between contaminants and meteoroids, and will determine their velocity and size distribution around the spacecraft environment. With two different color diode lasers, the contaminant and meteroid composition will also be determined based on laboratory calibration with different materials. Secondary particles dislodged from the top aluminum surface of the MOS detector will also be measured to determine the kinetic energy losses during energetic meteoroid impacts. The velocity range of this instrument is 0.1 m/s to more than 14 km/s, while its size sensitivity is from 0.2 microns to millimeter-sized particles. The particulate measurements in space of the kind proposed will be the first simultaneous multipurpose particulate experiment that includes velocities from very slow to hypervelocities, sizes from submicrometer- to pellet-sized diameters, chemical analysis of the particulate composition, and measurements of the kinetic energy losses after energetic impacts of meteroids. The experiment will provide contamination particles and orbital debris data that are critically needed for our present understanding of the space environment. The data will also be used to validate contamination and orbital debris models for predicting optimal configuration of future space sensors and for understanding their effects on sensitive surfaces such as mirrors, lenses, paints, and thermal blankets

Cost-effectiveness analysis of the management of distal ureteral stones in children

Objective To determine the most cost-effective approach to the management of distal ureteral stones in children given the potential for recurrent renal colic during a trial of passage versus potential stent discomfort and complications of ureteroscopy. Methods We developed a decision tree to project costs and clinical outcomes associated with observation, medical explusive therapy (MET), and ureteroscopy for the management of an index patient with a 4mm distal ureteral stone. We determined which strategy would be least costly and offer the most pain-free days within 30 days of diagnosis. We performed a one-way sensitivity analysis on the probability of successful stone passage with MET. We obtained probabilities from the literature and costs from the 2016 Pediatric Health Information System Database. Results Ureteroscopywas the costliest strategy but maximized the number of pain-free days within 30 days of diagnosis ($5,282/29 pain-free days). MET was less costly than ureteroscopybut also less effective ($615/21.8 pain-free days). Observation cost more than MET and was also less effective ($2,139/15.5 pain-free days). The one-way sensitivity analysis on the probability of successful stone passage with MET demonstrated that ureteroscopyalways has the highest net monetary benefits value and is therefore the recommended strategy given a fixed WTP. Discussion Using a rigorous decision-science approach, we found that ureteroscopy is the recommended strategy in children with small distal ureteral stones. Although it cost more than MET, it resulted in more pain-free days in the first 30 days following diagnosis given the faster resolution of the stone episode

The 24-h Movement Compositions in Weekday, Weekend Day or Four-Day Periods Differentially Associate with Fundamental Movement Skills

The aim of this study was to investigate the relationship between weekday, weekend day and four-day physical activity (PA) behaviours and fundamental movement skills (FMS) in British preschool children from a low socio-economic status background using compositional data analysis (CoDA). One hundred and eighty-five preschool children aged 3–4 years provided objectively assessed PA and sedentary behaviour (SB) data (GENEActiv accelerometer) and FMS (TGMD-2). The association of 24-h movement behaviours with FMS was explored using CoDA and isotemporal substitution (R Core Team, 3.6.1). When data were considered compositionally (SB, light PA (LPA), moderate and vigorous PA (MVPA)) and adjusted for age, BMI and sex, the weekday-derived composition predicted total motor competence (r2 = 0.07), locomotor (r2 = 0.08) and object control skills (r2 = 0.09); the weekend day-derived composition predicted total motor competence (r2 = 0.03) and object control skills (r2 = 0.03), the 4-day-derived composition predicted total motor competence (r2 = 0.07), locomotor (r2 = 0.07) and object control skills (r2 = 0.06) (all p < 0.05). Reallocation of 5 min of LPA at the expense of any behaviour was associated with significant improvements in total motor competence, locomotor and object control skills; for weekend-derived behaviours, MVPA was preferential. Considering movement behaviours over different time periods is required to better understand the effect of the 24-h movement composition on FMS in preschool children

Brand management and the marketing mix model

Abstract Brand management is typically defined as the way in which brands are positioned in the marketplace, both in terms of tangibles such as price, packaging and the marketing mix and intangibles such as consumer perceptions and brand equity. The conventional marketing mix model is often used to inform the tangible elements, but is lacking into two key aspects. Firstly, it ignores the role of intangibles. Secondly, the focus is solely on individual brands in isolation. This ignores the wider competitive context, where the decision to choose one brand is the simultaneous decision not to choose another. Successful brand management, however, requires a simultaneous holistic view of all players. To address both issues, this paper argues for a dynamic time series version of the discrete choice attraction model. Firstly, the demand system structure treats the entire category as a single unit, capturing competitive steal, cannibalisation, halo and category expansion effects of brand specific marketing. This provides accurate marketing ROI and budget allocation, facilitating the manufacturer-retailer relationship. Secondly, the time series approach allows us to quantify the evolution and drivers of consumer brand tastes -critical to understanding brand intangibles. This enables managers to set marketing strategy for optimal long-term brand performance

Epidural Analgesia Decreases Narcotic Requirements in Low Level Spina Bifida Patients Undergoing Urologic Laparotomy for Neurogenic Bladder and Bowel

Purpose Concern of anatomical anomalies and worsening neurologic symptoms has prevented widespread use of epidural catheters in patients with low level spina bifida (LLSB). We hypothesize that thoracic epidural placement in the T9-T10 interspace is safe and decreases narcotic requirements in LLSB patients following major open lower urinary tract reconstruction (LUTR). Materials and Methods We reviewed consecutive LLSB patients who had LUTR and epidurals for post-operative pain control. Controls were LLSB patients who received single shot transversus abdominis plane (TAP) blocks with similar procedures. Complications from epidural placement, including changes in motor and sensory status were recorded. Opioid consumption was calculated utilizing equivalent IV morphine doses. Mean and maximum pain scores on post-operative day (POD) 0-3 were calculated. Results 10 LLSB patients who had lower urinary tract reconstruction and epidurals were matched to 10 LLSB patients who had lower urinary tract reconstruction and transverse abdominis plane blocks. Groups were demographically similar. All had full abdominal sensation and functional levels at or below L3. No epidural complications or changes in neurological status were noted. The epidural group had decreased opioid consumption on POD 0-3 (0.75 mg/kg vs. 1.29 mg/kg, p=0.04). Pain scores were similar or improved in the epidural group. Conclusions Thoracic epidural analgesia appears to be a safe and effective opioid sparing option to assist with post-operative pain management following lower urinary tract reconstruction in LLSB patients