Single-particle Excitation Spectra of C60_{60} Molecules and Monolayers

In this paper we present calculations of single-particle excitation spectra of neutral and three-electron-doped Hubbard C$_{60}$ molecules and monolayers from large-scale quantum Monte Carlo simulations and cluster perturbation theory. By a comparison to experimental photoemission, inverse photoemission, and angle-resolved photoemission data, we estimate the intermolecular hopping integrals and the C$_{60}$ molecular orientation angle, finding agreement with recent X-ray photoelectron diffraction (XPD) experiments. Our results demonstrate that a simple effective Hubbard model, with intermediate coupling, $U=4t$, provides a reasonable basis for modeling the properties of C$_{60}$ compounds.Comment: 6 page

Two-stage hands-on technology activity to develop preservice teachers’ competency in applying science and mathematics concepts

This paper discusses the implementation of a two-stage hands-on technology learning activity, based on Dewey’s learning experience theory that is designed to enhance preservice teachers’ primary and secondary experiences in developing their competency to solve hands-on problems that apply science and mathematics concepts. The major conclusions were that: (1) preservice teachers understood the science and mathematics concepts related to the hands-on activity, but they need more help in exploring practical products of applying discipline related concepts for the purpose of stimulating their design ideas; and (2) the two-stage hands-on technology learning activity served as useful prompts in developing preservice teachers’ primary and secondary experiences in applying science and mathematics concepts during the design process. However, it was evident that preservice teachers still needed more training in improving their design ideas by the application of more in-depth related science and mathematics concepts

Associations of Emergency Department Length of Stay With Publicly Reported Quality-of-care Measures.

OBJECTIVE: The Institute of Medicine identified emergency department (ED) crowding as a critical threat to patient safety. We assess the association between changes in publicly reported ED length of stay (LOS) and changes in quality-of-care measures in a national cohort of hospitals. METHODS: Longitudinal analysis of 2012 and 2013 data from the American Hospital Association (AHA) Survey, Center for Medicare and Medicaid Services (CMS) Cost Reports, and CMS Hospital Compare. We included hospitals reporting Hospital Compare timeliness measure of LOS for admitted patients. We used AHA and CMS data to incorporate hospital predictors of interest. We used the method of first differences to test for relationships in the change over time between timeliness measures and six hospital-level measures. RESULTS: The cohort consisted of 2,619 hospitals. Each additional hour of ED LOS was associated with a 0.7% decrease in proportion of patients giving a top satisfaction rating, a 0.7% decrease in proportion of patients who would definitely recommend the hospital, and a 6-minute increase in time to pain management for long bone fracture (p \u3c 0.01 for all). A 1-hour increase in ED LOS is associated with a 44% increase in the odds of having an increase in left without being seen (95% confidence interval = 25% to 68%). ED LOS was not associated with hospital readmissions (p = 0.14) or time to percutaneous coronary intervention (p = 0.14). CONCLUSION: In this longitudinal study of hospitals across the United States, improvements in ED timeliness measures are associated with improvements in the patient experience

Active coupled-resonator optical waveguides. II. Current injection InP-InGaAsP Fabry-Perot resonator arrays

We investigate active, electrically pumped coupled-resonator optical waveguides (CROWs) in the form of InP-InGaAsP Fabry-Perot resonator arrays. We discuss the fabrication of these devices and present measurements of the transmission spectra. The signal-to-noise ratio is found to be a strong function of wavelength and degraded rapidly along the resonator chain away from the input. Our results highlight a number of ingredients toward practical implementations loss-compensated and amplifying CROWs

Two-dimensional Bragg grating lasers defined by electron-beam lithography

Two-dimensional Bragg grating (2DBG) lasers with two quarter-wave slip line defects have been designed and fabricated by electron-beam lithography and reactive ion etching. Unlike conventional two-dimensional photonic crystal defect lasers, which use a large refractive index perturbation to confine light in a plane, the 2DBG structures described here selectively control the longitudinal and transverse wave vector components using a weak index perturbation. Two line defects perpendicular to each other are introduced in the 2DBG to define the optical resonance condition in the longitudinal and transverse directions. In this article, we describe the lithography process used to pattern these devices. The 2DBG lasers were defined using polymethylmethacrylate resist exposed in a Leica Microsystems EBPG 5000+ electron-beam writer at 100 kV. A proximity correction code was used to obtain a uniform pattern distribution over a large area, and a dosage matrix was used to optimize the laser design parameters. Measurements of electrically pumped 2DBG lasers showed modal selection in both the longitudinal and transverse directions due to proper design of the grating and defects, making them promising candidates for single-mode, high power, high efficiency, large-area lasers

Ambient noise cross-correlation observations of fundamental and higher-mode Rayleigh wave propagation governed by basement resonance

Measurement of basement seismic resonance frequencies can elucidate shallow velocity structure, an important factor in earthquake hazard estimation. Ambient noise cross correlation, which is well-suited to studying shallow earth structure, is commonly used to analyze fundamental-mode Rayleigh waves and, increasingly, Love waves. Here we show via multicomponent ambient noise cross correlation that the basement resonance frequency in the Canterbury region of New Zealand can be straightforwardly determined based on the horizontal to vertical amplitude ratio (H/V ratio) of the first higher-mode Rayleigh waves. At periods of 1–3 s, the first higher-mode is evident on the radial-radial cross-correlation functions but almost absent in the vertical-vertical cross-correlation functions, implying longitudinal motion and a high H/V ratio. A one-dimensional regional velocity model incorporating a ~ 1.5 km-thick sedimentary layer fits both the observed H/V ratio and Rayleigh wave group velocity. Similar analysis may enable resonance characteristics of other sedimentary basins to be determined

Female Sex Development and Reproductive Duct Formation Depend on Wnt4a in Zebrafish.

In laboratory strains of zebrafish, sex determination occurs in the absence of a typical sex chromosome and it is not known what regulates the proportion of animals that develop as males or females. Many sex determination and gonad differentiation genes that act downstream of a sex chromosome are well conserved among vertebrates, but studies that test their contribution to this process have mostly been limited to mammalian models. In mammals, WNT4 is a signaling ligand that is essential for ovary and Müllerian duct development, where it antagonizes the male-promoting FGF9 signal. Wnt4 is well conserved across all vertebrates, but it is not known if Wnt4 plays a role in sex determination and/or the differentiation of sex organs in nonmammalian vertebrates. This question is especially interesting in teleosts, such as zebrafish, because they lack an Fgf9 ortholog. Here we show that wnt4a is the ortholog of mammalian Wnt4, and that wnt4b was present in the last common ancestor of humans and zebrafish, but was lost in mammals. We show that wnt4a loss-of-function mutants develop predominantly as males and conclude that wnt4a activity promotes female sex determination and/or differentiation in zebrafish. Additionally, both male and female wnt4a mutants are sterile due to defects in reproductive duct development. Together these results strongly argue that Wnt4a is a conserved regulator of female sex determination and reproductive duct development in mammalian and nonmammalian vertebrates

Facilitators and barriers to the successful implementation of pediatric antibacterial drug trials: Findings from CTTI's survey of investigators.

An urgent need exists to develop new antibacterial drugs for children. We conducted research with investigators of pediatric antibacterial drug trials to identify facilitators and barriers in the conduct of these trials. Seventy-three investigators completed an online survey assessing the importance of 15 facilitators (grouped in 5 topical categories) and the severity of 36 barriers (grouped in 6 topical categories) to implementing pediatric antibacterial drug trials. Analysis focused on the identification of key factors that facilitate the successful implementation of pediatric antibacterial drug trials and the key barriers to implementation. Almost all investigators identified two factors as very important facilitators: having site personnel for enrollment and having adequate funding. Other top factors were related to staffing. Among the barriers, factors related to parent concerns and consent were prominent, particularly obtaining parental consent when there was disagreement between parents, concerns about the number of blood draws, and concerns about the number of invasive procedures. Having overly narrow eligibility criteria was also identified as a major barrier. The survey findings suggest three areas in which to focus efforts to help facilitate ongoing drug development: (1) improving engagement with parents of children who may be eligible to enroll in a pediatric antibacterial drug trial, (2) broadening inclusion criteria to allow more participants to enroll, and (3) ensuring adequate staffing and establishing sustainable financial strategies, such as funding pediatric trial networks. The pediatric antibacterial drug trials enterprise is likely to benefit from focused efforts by all stakeholders to remove barriers and enhance facilitation

A Study of the Meteorological Conditions Associated with Anomalously Early and Late Openings of a Northwest Territories Winter Road

In the Canadian Arctic, winter roads are engineered across the frozen land, rivers, and lakes. The strength and longevity of these roads depend on particular weather conditions. Our research focuses on the winter road between Tulita and Norman Wells, Northwest Territories, which has been maintained officially by the territorial government since 1982. Statistical analysis of the opening dates for the winter road showed five seasons with extremely early dates and five with extremely late dates. The extremely early-opening seasons are distinguished by anomalously high sea-level pressures, anomalously cold tropospheric air, and northwesterly surface winds during the November prior to the road opening. The extremely late-opening seasons are characterized by an anomalously strong Aleutian low in the preceding November. The extremely late-opening years are correlated with strong El Niño seasons, whereas the extremely early-opening years are not systematically associated with teleconnection patterns. Our analysis of meteorological conditions near Norman Wells, associated with the extreme opening dates for this winter road, may provide planners with more precise information germane to this road construction.Dans l’Arctique canadien, les routes hivernales sont construites sur le sol, les lacs et les rivières gelées. La solidité et la durabilité de ces routes dépendent de conditions météorologiques particulières. Nos recherches mettent l’emphase sur la route hivernale officiellement entretenue par le gouvernement territorial depuis 1982, entre Tulita et Norman Wells dans les Territoires du Nord-Ouest. L’analyse des statistiques relativement aux dates d’ouverture de cette route ont permis de dénoter des dates d’ouverture très hâtives dans le cas de cinq saisons, et très tardives dans le cas de cinq autres saisons. Les années où l’ouverture est extrêmement hâtive sont distinguées par une pression au niveau de la mer irrégulièrement haute, de l’air troposphérique irrégulièrement froid, et des vents de surface du nord-ouest durant le mois de novembre précédant l’ouverture de la route. Les cinq années dont l’ouverture est extrêmement tardive sont précédées par un mois de novembre où la basse pression des Aléoutiennes y est irrégulièrement forte. Les résultats démontrent que les années où l’ouverture est extrêmement tardive sont des saisons influencées par El Niño tandis que les années dont l’ouverture est extrêmement hâtive ne sont pas systématiquement associées avec des signaux de téléconnexions. L’analyse des conditions météorologiques près de Norman Wells, associée avec les dates d’ouvertures extrêmes pour cette route, procure aux planificateurs de ces routes de l’information plus précise pour la construction de celles-ci

Perceived barriers to pediatrician and family practitioner participation in pediatric clinical trials: Findings from the Clinical Trials Transformation Initiative.

Despite legislation to stimulate pediatric drug development through clinical trials, enrolling children in trials continues to be challenging. Non-investigator (those who have never served as a clinical trial investigator) providers are essential to recruitment of pediatric patients, but little is known regarding the specific barriers that limit pediatric providers from participating in and referring their patients to clinical trials. We conducted an online survey of pediatric providers from a wide variety of practice types across the United States to evaluate their attitudes and awareness of pediatric clinical trials. Using a 4-point Likert scale, providers described their perception of potential barriers to their practice serving as a site for pediatric clinical trials. Of the 136 providers surveyed, 52/136 (38%) had previously referred a pediatric patient to a trial, and only 17/136 (12%) had ever been an investigator for a pediatric trial. Lack of awareness of existing pediatric trials was a major barrier to patient referral by providers, in addition to consideration of trial risks, distance to the site, and time needed to discuss trial participation with parents. Overall, providers perceived greater challenges related to parental concerns and parent or child logistical barriers than study implementation and ethics or regulatory barriers as barriers to their practice serving as a trial site. Providers who had previously been an investigator for a pediatric trial were less likely to be concerned with potential barriers than non-investigators. Understanding the barriers that limit pediatric providers from collaboration or inhibit their participation is key to designing effective interventions to optimize pediatric trial participation