Survival Analysis: An Exact Method for Rare Events

Conventional asymptotic methods for survival analysis work well when sample sizes are at least moderately sufficient. When dealing with small sample sizes or rare events, the results from these methods have the potential to be inaccurate or misleading. To handle such data, an exact method is proposed and compared against two other methods: 1) the Cox proportional hazards model and 2) stratified logistic regression for discrete survival analysis data

The Influence of Secondary Principals\u27 Perceived Trust of Assistant Principals and Central Office Supervisors on Principal Self-Efficacy for Instructional Leadership

Although self-efficacy has been studied widely in education, variables associated with the self-efficacy of principals have received relatively limited attention. The current study investigated the relationship between secondary principals’ perceptions of trust in their assistant principal and central office supervisor and their own self-efficacy for instructional leadership. Surveys were collected from 80 secondary principals. Open-ended questions were utilized to gain greater understanding of the behaviors contributing to principals’ perceptions of trust and feelings of self-efficacy. Data were analyzed using correlation and multiple regression. Quantitative results revealed that no statistically significant relationship is present between trust perceptions in the relationships investigated and principals’ self-efficacy for instructional leadership. Analysis of the open-ended responses indicates that behaviors categorized as offer support, dependability, communication, and competence were the most frequently cited by principals as contributing to trust. In reference to behaviors that serve as a source of self-efficacy, principals referenced those categorized as supports my decision making, engage in support behaviors, and verbal persuasion most frequently. Responses including related to instructional leadership were noticeably absent from the open-ended responses. Recognizing the value of trusting relationships and instructional leadership established in existing research, the discussion of this study outlines the necessity to balance efforts for both. Principal perceptions of trust may be a necessary but insufficient condition for principals to experience self-efficacy for instructional leadership. Practical instructional leadership skills are also required. Recommendations are made that principal preparation programs, district leaders, and assistant principals take intentional action to support the development of instructional leadership skills to build principal self-efficacy for instructional leadership

The economic potential of switchgrass as a viable biofuel alternative

To be commercially viable as a bioenergy feedstock, switchgrass must be cost-competitive. Switchgrass production and delivery costs are calculated for the Chariton Valley Switchgrass Biomass Project located in the Chariton Valley, Iowa. Sensitivity analyses are performed to determine which variables have the greatest impact on cost. Switchgrass production costs would require higher than expected market prices, and therefore various incentive payment options are considered. The incentive payments attempt to encapsulate the positive environmental attributes from the production of switchgrass as well as using switchgrass as a clean energy coal substitute. A modified CRP payment, carbon payment, and green tag payment are all considered, and their relative advantages and disadvantages are discussed. The modified CRP payment and the green tag payment are shown to have significant potential for offsetting high switchgrass costs of production

The potential of computed crystal energy landscapes to aid solid-form development

Solid-form screening to identify all solid forms of an active pharmaceutical ingredient (API) has become increasingly important in ensuring the quality by design of pharmaceutical products and their manufacturing processes. However; despite considerable enlargement of the range of techniques that have been shown capable of producing novel solid forms; it is possible that practically important forms might not be found in the short timescales currently allowed for solid-form screening. Here; we report on the state-of-the-art use of computed crystal energy landscapes to complement pharmaceutical solid-form screening. We illustrate how crystal energy landscapes can help establish molecular-level understanding of the crystallization behavior of APIs and enhance the ability of solid-form screening to facilitate pharmaceutical development

Coherent two-dimensional multiphoton photoelectron spectroscopy of metal surfaces

Light interacting with metals elicits an ultrafast coherent many-body screening response on sub- to few-femtosecond time-scales, which makes its experimental observation challenging. Here, we describe the coherent two-dimensional (2D) multi-photon photoemission study of the Shockley surface state (SS) of Ag(111) as a benchmark for spectroscopy of the coherent nonlinear response of metals to an optical field in the perturbative regime. Employing interferometrically time-resolved multi-photon photoemission spectroscopy (ITR-mPP), we correlate the coherent polarizations and populations excited in the sample with final photoelectron distributions where the interaction terminates. By measuring the non-resonant 3- and 4-photon photoemission of the SS state, as well as its replica structures in the above-threshold photoemission (ATP), we record the coherent response of the Ag(111) surface by 2D photoemission spectroscopy and relate it to its band structure. We interpret the mPP process by an optical Bloch equation (OBE) model, which reproduces the main features of the surface state coherent polarization dynamics recorded in ITR-mPP experiments: The spectroscopic components of the 2D photoelectron spectra are shown to depend on the nonlinear orders of the coherent photoemission process m as well as on the induced coherence n.Comment: 34 pages, 8 figures in main paper, pages 33 and 34: supplemental material, 1 figur

The Structure and Function of Urban Pharmacies: Visits to Community Pharmacies in Inner-City Chicago

Visits were made to 21 pharmacies in two poor neighborhoods on the west side of Chicago and interviews conducted with pharmacists-in-charge. The objective of the study was to provide a comprehensive description of the function, capabilities, and problems of urban pharmacy. We present results on the structure and function of these inner-city pharmacies. The pharmacies fit one of three structural forms: chain, independent, or medical center. The majority of respondents viewed the function of the inner-city pharmacy as patient-centered but also identified several barriers to effective patient communication. The results suggest that inner-city physicians and pharmacists should communicate with patients more often and in ways that patients understand. Also, Medicaid and other drug insurance programs should develop patient information networks and coverage packages intended to maximize patient health status

Sensing Defects during Directed-Energy Additive Manufacturing of Metal Parts using Optical Emissions Spectroscopy

Critical components produced via additive manufacturing must be free of unwanted defects. While defects may be detectable after deposition using nondestructive testing techniques, detecting defects during the deposition process offers many benefits: it may enable users to interrupt deposition to repair the part, or to abort deposition to minimize further loss of time and material. Here, we present a method for real-time defect detection during directed-energy additive manufacturing of metals. The method utilized optical emission spectroscopy and a custom-built data acquisition and control infrastructure. It was implemented on a LENS MR-7 machine, and employed during manufacturing of Ti-6Al-4V components in which defects were intentionally introduced. Emission spectra were correlated with defect locations, determined via computed tomography and metallographic cross-sectioning. Preliminary results indicated that defect formation was correlated with atomic titanium (Ti I) and Vanadium (V I) emissions and that measurement of the line-to-continuum ratio for line emissions could be used for defect detection. Based on these findings, sensing strategies for defect detection and, potentially, in-situ-defect repair may be realizable.Mechanical Engineerin

Process Monitoring of Directed-Energy Deposition of Inconel-718 via Plume Imaging

Laser-metal interactions typically results in vaporization and plume formation. These phenomena are complex and depend upon the details of the laser-vapor-melt interactions. As such, plume characteristics are sensitive to changes in process characteristics. Here, a spectroscopy-based imaging technique is presented for the monitoring of directed energy deposition of Inconel 718. Plume geometry is shown to be related to the processing parameters and geometry of single-bead deposits.Mechanical Engineerin

Get a GRIP on Comprehension

Durkin\u27s research (1978-79) has indicated that much more time is spent testing reading comprehension than teaching it. Consequently, all reading comprehension skills need to be taught by the teacher to the students in the classroom. Since making inferences is a necessary comprehension skill when reading across the curriculum (Gordon, 1985), it also must be taught. However, many children find it difficult to make inferences because they are required not only to derive a conclusion from the facts or premises found in their reading materials, but in many cases, they must go beyond the text to their own knowledge and experiences for information. Thus, prior knowledge which student bring to the text, as well as their sensitivity to the text information, are essential aspects of inferential comprehension

Can computed crystal energy landscapes help understand pharmaceutical solids?

Computational crystal structure prediction (CSP) methods can now be applied to the smaller pharmaceutical molecules currently in drug development. We review the recent uses of computed crystal energy landscapes for pharmaceuticals, concentrating on examples where they have been used in collaboration with industrial-style experimental solid form screening. There is a strong complementarity in aiding experiment to find and characterise practically important solid forms and understanding the nature of the solid form landscape