927 research outputs found

    Persistent Decadal-Scale Rainfall Variability in the Tropical South Pacific Convergence Zone Through the Past Six Centuries

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    Modern Pacific decadal variability (PDV) has global impacts; hence records of PDV from the pre-instrumental period are needed to better inform models that are used to project future climate variability. We focus here on reconstructing rainfall in the western tropical Pacific (Solomon Islands; similar to 9.5 degrees S, similar to 160 degrees E), a region directly influenced by PDV, using cave deposits (stalagmite). A relationship is developed between delta O-18 variations in the stalagmite and local rainfall amount to produce a 600 yr record of rainfall variability from the South Pacific Convergence Zone (SPCZ). We present evidence for large (similar to 1.5 m), abrupt, and periodic changes in total annual rainfall amount on decadal to multidecadal timescales since 1423 +/- 5 CE (Common Era) in the Solomon Islands. The timing of the decadal changes in rainfall inferred from the 20th-century portion of the stalagmite delta O-18 record coincides with previously identified decadal shifts in PDV-related Pacific ocean-atmosphere behavior (Clement et al., 2011; Deser et al., 2004). The Solomons record of PDV is not associated with variations in external forcings, but rather results from internal climate variability. The 600 yr Solomon Islands stalagmite delta O-18 record indicates that decadal oscillations in rainfall are a persistent characteristic of SPCZ-related climate variability.Taiwan ROC NSCNTU 101-2116-M-002-009, 102-2116-M-002-016, 101R7625Geological Science

    Granitic Boulder Erosion Caused by Chaparral Wildfire: Implications for Cosmogenic Radionuclide Dating of Bedrock Surfaces

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    Rock surface erosion by wildfire is significant and widespread but has not been quantified in southern California or for chaparral ecosystems. Quantifying the surface erosion of bedrock outcrops and boulders is critical for determination of age using cosmogenic radionuclide techniques, as even modest surface erosion removes the accumulation of the cosmogenic radionuclides and causes significant underestimate of age. This study documents the effects on three large granitic boulders following the Esperanza Fire of 2006 in southern California. Spalled rock fragments were quantified by measuring the removed rock volume from each measured boulder. Between 7% and 55% of the total surface area of the boulders spalled in this single fire. The volume of spalled material, when normalized across the entire surface area, represents a mean surface lowering of 0.7–12.3 mm. Spalled material was thicker on the flanks of the boulders, and the height of the fire effects significantly exceeded the height of the vegetation prior to the wildfire. Surface erosion of boulders and bedrock outcrops as a result of wildfire spalling results in fresh surfaces that appear unaffected by chemical weathering. Such surfaces may be preferentially selected by researchers for cosmogenic surface dating because of their fresh appearance, leading to an underestimate of age

    Are Alternative School Leader Preparation Programs Really Needed to Prepare Next-Generation School Leaders?

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    The essays in this chapter focus on the issue of how best to recruit the very best administrative talent to leadership positions in schools. For years, the accepted practice has been for school leaders to be prepared through traditional school administration programs with higher education institutions. These programs, almost exclusively housed within colleges and schools of education, consisted of a range of courses from school law to school finance, often with associated and embedded field and clinical components. The focus on school leader preparation has emerged in partial response to the No Child Left Behind legislation. Clearly, there are expanded expectations regarding what principals can and should be able to do in order to be effective as school leaders. Critics of traditional preparation programs, such as Frederick Hess of the American Enterprise Institute, argue that far too little of the principal preparation curriculum focuses on accountability while far too much deals with issues that simply do not create opportunities for principals to understand how to use data and how to effectively evaluate the personnel who report to them. Critics such as Hess and others expect principals to be able to use data in ways that will help them manage school programs so that all students are able to achieve to their full potential and so that every teacher can be productive in terms of fostering essential and necessary student academic growth. The critics challenge whether traditional programs have been able to keep pace with the educational demands that are a part of a competitive, globalized economy. Whether such critics have it right is debatable, but what both critics and advocates of traditional programs agree on is the fact that the principal is absolutely critical to the success of any school program. Teachers need a school leader who understands how to manage a complex educational environment. The question remains about how best to prepare such school leaders, which serves as the focus for this chapter. This is not the first time that there have been serious and ongoing efforts to upgrade the quality of administrator preparation, but even with current and previous efforts, serious concerns have surfaced as to whether traditional programs can really deliver to PreK-12 schools the intellectual talent needed to foster educational excellence. Some critics believe that the real solution to the problem is to bring persons with business degrees into schools who understand how to operate, manage, and market businesses. Indeed, some universities around the country are now working through their business schools to prepare individuals who have interests in taking their business degrees into educational environments for the purpose of serving as principals or school leaders. Emmy L. Partin and Jamie Davies O\u27Leary, from the Thomas B. Fordham Institute, make the case that more nontraditional, nonuniversity-based options are needed. They argue that programs run by charter management organizations or selected non profits, such as New Leaders for New Schools, create new vehicles for attracting talent to school leadership positions that simply are not being evidenced through traditional, university-based programs. In addition, Partin and O\u27Leary assert that many of the nontraditional options place emphasis on preparing administrators for some of the nation\u27s most poorly performing schools, where the need for quality school leaders is most pronounced. Theodore J. Kowalski from the University of Dayton takes a different view. Kowalski is one of the nation\u27s thought leaders in terms of school leader preparation practices. He has concerns that the alternatives will deprofessionalize school leadership at precisely the time when more professional skills and understandings are required by those assuming the difficult responsibilities associated with school administration. Kowalski perceives that, in general, no shortage of administrative talent exists in the United States and that traditional programs are much better suited to address the preparation demands that are currently found in the educational marketplace. These two essays capture in a significant way much of the active and substantive debate currently found in the professional literature about how to ensure that the nation secures the school leaders it needs. Everyone agrees that school principals and district superintendents are critical ingredients to educational excellence. What these two essays highlight is the very different approaches that policymakers and practitioners have taken relative to how best to recruit and train the next generation of school leaders. In reading these two essays, consider the following questions. First, will emerging alternatives really deprofessionalize what it means to be a school leader? Second, if it is really essential to have the right people in a leadership position, how should schools best recruit the talent they need? Finally, is the key to recruiting more professional principals paying them more so that you attract better quality or training them differently so that they are assured of possessing skills they need for success? — Thomas J. Lasley II, University of Dayto

    Evolution of structural and electronic properties of highly mismatched InSb films

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    We have investigated the evolution of structural and electronic properties of highly mismatched InSb films, with thicknesses ranging from 0.1 to 1.5 μm. Atomic force microscopy, cross-sectional transmission electron microscopy, and high-resolution x-ray diffraction show that the 0.1 μm films are nearly fully relaxed and consist of partially coalesced islands, which apparently contain threading dislocations at their boundaries. As the film thickness increases beyond 0.2 μm, the island coalescence is complete and the residual strain is reduced. Although the epilayers have relaxed equally in the 〈110〉 in-plane directions, the epilayer rotation about an in-plane axis (epilayer tilt) is not equal in both 〈110〉 in-plane directions. Interestingly, the island-like surface features tend to be preferentially elongated along the axis of epilayer tilt. Furthermore, epilayer tilt which increases the substrate offcut (reverse tilt) is evident in the [110] direction. High-resolution transmission electron microscopy indicates that both pure-edge and 60° misfit dislocations contribute to the relaxation of strain. In addition, as the film thickness increases, the threading dislocation density decreases, while the corresponding room-temperature electron mobility increases. The other structural features, including the residual strain, and the surface and interface roughness, do not appear to impact the electron mobility in these InSb films. Together, these results suggest that free-carrier scattering from the threading dislocations is the primary room-temperature mobility-limiting mechanism in highly mismatched InSb films. Finally, we show quantitatively that free-carrier scattering from the lattice dilation associated with threading dislocations, rather than scattering from a depletion potential surrounding the dislocations, is the dominant factor limiting the electron mobility. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70332/2/JAPIAU-88-11-6276-1.pd

    A prospective adaptive utility trial to validate performance of a novel urine exosome gene expression assay to predict high-grade prostate cancer in patients with prostate-specific antigen 2-10ng/ml at initial biopsy

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    BACKGROUND: Discriminating indolent from clinically significant prostate cancer (PCa) in the initial biopsy setting remains an important issue. Prospectively evaluated diagnostic assays are necessary to ensure efficacy and clinical adoption. OBJECTIVE: Performance and utility assessment of ExoDx Prostate (IntelliScore) (EPI) urine exosome gene expression assay versus standard clinical parameters for discriminating Grade Group (GG) ≥2 PCa from GG1 PCa and benign disease on initial biopsy. DESIGN, SETTING, AND PARTICIPANTS: A two-phase adaptive clinical utility study (NCT03031418) comparing EPI results with biopsy outcomes in men, with age ≥50 yr and prostate-specific antigen (PSA) 2-10ng/ml, scheduled for initial prostate biopsy. After EPI performance assessment during phase I, a clinical implementation document (ie, CarePath) was developed for utilizing the EPI test in phase II, where the biopsy decision is uncertain. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Performance evaluation of the EPI test in patients enrolled in phase I and publication of a consensus CarePath for phase II. RESULTS AND LIMITATIONS: In a total of 503 patients, with median age of 64 yr, median PSA 5.4ng/ml, 14% African American, 70% Caucasian, 53% positive biopsy rate (22% GG1, 17% GG2, and 15% ≥ GG3), EPI was superior to an optimized model of standard clinical parameters with an area under the curve (AUC) 0.70 versus 0.62, respectively, comparable with previously published results (n=519 patients, EPI AUC 0.71). Validated cut-point 15.6 would avoid 26% of unnecessary prostate biopsies and 20% of total biopsies, with negative predictive value (NPV) 89% and missing 7% of ≥GG2 PCa. Alternative cut-point 20 would avoid 40% of unnecessary biopsies and 31% of total biopsies, with NPV 89% and missing 11% of ≥GG2 PCa. The clinical investigators reached consensus recommending use of the 15.6 cut-point for phase II. Outcome of the decision impact cohort in phase II will be reported separately. CONCLUSIONS: EPI is a noninvasive, easy-to-use, gene expression urine assay, which has now been successfully validated in over 1000 patients across two prospective validation trials to stratify risk of ≥GG2 from GG1 cancer and benign disease. The test improves identification of patients with higher grade disease and would reduce the total number of unnecessary biopsies. PATIENT SUMMARY: It is challenging to predict which men are likely to have high-grade prostate cancer (PCa) at initial biopsy with prostate-specific antigen 2-10ng/ml. This study further demonstrates that the ExoDx Prostate (IntelliScore) test can predict ≥GG2 PCa at initial biopsy and defer unnecessary biopsies better than existing risk calculator\u27s and standard clinical data

    Zee electrical interconnect

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    An interconnect, having some length, that reliably connects two conductors separated by the length of the interconnect when the connection is made but in which one length if unstressed would change relative to the other in operation. The interconnect comprises a base element an intermediate element and a top element. Each element is rectangular and formed of a conducting material and has opposed ends. The elements are arranged in a generally Z-shape with the base element having one end adapted to be connected to one conductor. The top element has one end adapted to be connected to another conductor and the intermediate element has its ends disposed against the other end of the base and the top element. Brazes mechanically and electrically interconnect the intermediate element to the base and the top elements proximate the corresponding ends of the elements. When the respective ends of the base and the top elements are connected to the conductors, an electrical connection is formed therebetween, and when the conductors are relatively moved or the interconnect elements change length the elements accommodate the changes and the associated compression and tension forces in such a way that the interconnect does not mechanically fatigue

    Quantifying site-level usage and certainty of absence for an invasive species through occupancy analysis of camera-trap data

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    Copyright Springer International Publishing This document is a U.S. government work and is not subject to copyright in the United States. https://doi.org/10.1007/s10530-017-1579-
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