Insulator-to-Metal Transition in Selenium-Hyperdoped Silicon: Observation and Origin

Hyperdoping has emerged as a promising method for designing semiconductors with unique optical and electronic properties, although such properties currently lack a clear microscopic explanation. Combining computational and experimental evidence, we probe the origin of sub-band gap optical absorption and metallicity in Se-hyperdoped Si. We show that sub-band gap absorption arises from direct defect-to-conduction band transitions rather than free carrier absorption. Density functional theory predicts the Se-induced insulator-to-metal transition arises from merging of defect and conduction bands, at a concentration in excellent agreement with experiment. Quantum Monte Carlo calculations confirm the critical concentration, demonstrate that correlation is important to describing the transition accurately, and suggest that it is a classic impurity-driven Mott transition.Comment: 5 pages, 3 figures (PRL formatted

Ambulatory Electromyogram Activity in the Upper Trapezius Region: Patients With Muscle Pain vs. Pain-free Control Subjects

Study Design: This study compared the ambulatory electromyogram activity of persons reporting pain in the shoulder and cervical regions with an equal group of persons not reporting such pain. Ambulatory electromyogram data were obtained over 3-day periods. In addition, all participants completed several standard psychological questionnaires. Objectives: The results were analyzed with inferential statistics to determine whether subjects reporting significant pain in the shoulder and cervical regions had greater ambulatory electromyogram activity than an equal number of subjects not reporting pain. Summary of Background Data: Considerable controversy exists regarding the role of muscle activity in the etiology and maintenance of muscle pain disorders. Given the availability of ambulatory recording devices that can provide a detailed record of muscle activity over an extended period of time, the present research was conducted to determine whether persons reporting shoulder and cervical pain could be differentiated from a group of normal subjects. Methods: All subjects (N = 20) completed a battery of tests with standardized psychometric instruments and then were fitted with ambulatory electromyogram monitors to record electromyographic activity of the upper trapezius region of the dominant side; the time, duration, and amplitude of electromyogram activity greater than 2 μV was recorded. The monitors were worn during normal working hours (mean, 6.2 hours per day) over 3 consecutive days. In addition to wearing the monitors, all subjects completed hourly self-ratings of perceived muscle tension during the recording periods. Results: As expected, subjects with muscle pain reported significantly more pain (mean, 4.9) than did the normal control subjects (mean, 0.9), t(15) = 3.29, P \u3c 0.01. However, patients with muscle pain did not have greater average electromyogram activity (mean, 6.4 μV) over the 3-day period as compared to the normal controls (mean, 7.1 μV), t(18) = -0.25, P \u3c 0.80. Self-monitoring of perceived muscle tension also did not reveal differences between pain subjects and the normal control subjects (P \u3c 0.75). Conclusions: Ambulatory measurements of electromyogram activity did not differentiate persons reporting upper trapezius or cervical pain from those that did not report such pain. Persons reporting pain are also not distinguishable from normal control subjects on a variety of self-report measures. These results raise questions regarding the role of ambulatory electromyogram recordings in the evaluation and treatment of muscle pain disorders

Relationship of first hollow stem and heading in winter wheat

The majority of wheat (Triticum aestivum L.) in the southern Great Plains is produced as a dual-purpose crop enterprise. Profitability of the system is highly dependent on removal of cattle (Bos taurus L.) from wheat pastures at the first-hollowstem stage of growth. A previous survey implied that earliness of first hollow stem and earliness of heading are independent traits, which would allow a grower to select a cultivar with late first hollow stem without sacrificing early maturity. We evaluated first hollow stem and heading records for 52 hard winter wheat lines (49 commercially available winter wheat cultivars and three advanced experimental lines) during a 7- yr period at Stillwater, OK. Our analysis shows a positive, linear relationship between the occurrence of first hollow stem and heading in wheat when these phenological events were expressed as a function of cumulative thermal units after 1 January. When expressed in terms of calendar date, however, intervals between the earliest and latest cultivars for the first-hollow-stem stage were much greater than those for heading date. Overall, our analysis indicates that among commercially available cultivars and advanced experimental lines, choosing a cultivar with later occurrence of first hollow stem will also result in later heading in the same given environment.Peer reviewedPlant and Soil SciencesStatistic

Genomics reveals historic and contemporary transmission dynamics of a bacterial disease among wildlife and livestock

Whole-genome sequencing has provided fundamental insights into infectious disease epidemiology, but has rarely been used for examining transmission dynamics of a bacterial pathogen in wildlife. In the Greater Yellowstone Ecosystem (GYE), outbreaks of brucellosis have increased in cattle along with rising seroprevalence in elk. Here we use a genomic approach to examine Brucella abortus evolution, cross-species transmission and spatial spread in the GYE. We find that brucellosis was introduced into wildlife in this region at least five times. The diffusion rate varies among Brucella lineages (∼3 to 8 km per year) and over time. We also estimate 12 host transitions from bison to elk, and 5 from elk to bison. Our results support the notion that free-ranging elk are currently a self-sustaining brucellosis reservoir and the source of livestock infections, and that control measures in bison are unlikely to affect the dynamics of unrelated strains circulating in nearby elk populations

Central line-associated blood stream infections in pediatric intensive care units: Longitudinal trends and compliance with bundle strategies.

BACKGROUND: Knowing the temporal trend central line-associated bloodstream infection (CLABSI) rates among U.S. pediatric intensive care units (PICUs), the current extent of central line bundle compliance, and the impact of compliance on rates is necessary to understand what has been accomplished and can be improved in CLABSI prevention. METHODS: This is a longitudinal study of PICUs in National Healthcare Safety Network hospitals and a cross-sectional survey of directors and managers of infection prevention and control departments regarding PICU CLABSI prevention practices, including self-reported compliance with elements of central line bundles. Associations between 2011-2012 PICU CLABSI rates and infection prevention practices were examined. RESULTS: Reported CLABSI rates decreased during the study period, from 5.8 per 1,000 line days in 2006 to 1.4 in 2011-2012 (P \u3c .001). Although 73% of PICUs had policies for all central line prevention practices, only 35% of those with policies reported ≥95% compliance. PICUs with ≥95% compliance with central line infection prevention policies had lower reported CLABSI rates, but this association was statistically insignificant. CONCLUSION: There was a nonsignificant trend in decreasing CLABSI rates as PICUs improved bundle policy compliance. Given that few PICUs reported full compliance with these policies, PICUs increasing their efforts to comply with these policies may help reduce CLABSI rates

Development of a Maxwell X-57 High Lift Motor Reference Design

NASA's all-electric X-57 airplane will utilize 14 electric motors, of which 12 are exclusively for lift augmentation during takeoff and landing. This report covers the design and development process taken to create an open reference model representative of the 12 lift augmenting motors. A combined worst case scenario was used as the design point, which represents the simultaneously occurring worst case aspects of thermal, static stress, electromagnetic, and rotor dynamic conditions. This work also highlights the tightly coupled nature of aerospace electric motor design, requiring constant iteration between all disciplines involved. Further adding to the uniqueness is the cooling method, which is limited to nacelle skin forced convection cooling only, no internal air flow is permitted. The stator outer diameter limit of 156.45 mm greatly impacts the degree of coupling between the electromagnetic design with the thermal analysis. The permanent magnet synchronous motor developed here operates between 385 V and 538 V, at a peak current of 50 A. Detailed electromagnetic, thermal, static load, and rotordynamic analysis was completed for this electric motor; all of which are required for a full design. The rotordynamic analysis took into consideration the motor housing which is designed specifically for this motor. The final electric motor has a mass of 2.34 kg, produces 24.1 Nm of torque with a specific power of 5.56 kW/kg, and has an efficiency of 96.61% at the combined worst case design point

Discharge Age and Weight for Very Preterm Infants in Six Countries: 2012-2020

BACKGROUND Postmenstrual age for surviving infants without congenital anomalies born at 24-29 weeks' gestational age from 2005 to 2018 in the USA increased 8 days, discharge weight increased 316 grams, and median discharge weight z-score increased 0.19 standard units. We asked whether increases were observed in other countries. METHODS We evaluated postmenstrual age, weight, and weight z-score at discharge of surviving infants without congenital anomalies born at 24-29 weeks' gestational age admitted to Vermont Oxford Network member hospitals in Austria, Ireland, Italy, Switzerland, the UK, and the USA from 2012 to 2020. RESULTS After adjustment, the median postmenstrual age at discharge increased significantly in Austria (3.6 days, 99% CI [1.0, 6.3]), Italy (4.0 days [2.3, 5.6]), and the USA (5.4 days [5.0, 5.8]). Median discharge weight increased significantly in Austria (181 grams, 99% CI [95, 267]), Ireland (234 [143, 325]), Italy (133 [83, 182]), and the USA (207 [194, 220]). Median discharge weight z-score increased in Ireland (0.24 standard units, 99% CI [0.12, 0.36]) and the USA (0.15 [0.13, 0.16]). Discharge on human milk increased in Italy, Switzerland, and the UK, while going home on cardiorespiratory monitors decreased in Austria, Ireland, and USA and going home on oxygen decreased in Ireland. CONCLUSIONS In this international cohort of neonatal intensive care units, postmenstrual discharge age and weight increased in some, but not all, countries. Processes of care at discharge did not change in conjunction with age and weight increases

Dual-purpose wheat: Management for forage and grain production

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