976 research outputs found
Polyfunctional fluorosilicone composition, method for making, and use
A fluorosilicone crosslinker and method for making is provided. Reaction is effected between a silanol terminated polyfluoroalkyl silicone fluid and a polyalkoxysilane in the presence of a Platinum Group Metal catalyst. The fluorosilicone crosslinker can be used in combination with a silanol terminated fluoroalkyl substituted polydiorganosiloxane to formulate a neutral, condensation curable, solvent resistant sealant
Predicting QSO Continua in the Ly Alpha Forest
We present a method to make predictions with sets of correlated data values,
in this case QSO flux spectra. We predict the continuum in the Lyman-Alpha
forest of a QSO, from 1020 -- 1216 A, using the spectrum of that QSO from 1216
-- 1600 A . We find correlations between the unabsorbed flux in these two
wavelengths regions in the HST spectra of 50 QSOs. We use principal component
analysis (PCA) to summarize the variety of these spectra and we relate the
weights of the principal components for 1020 -- 1600 A to the weights for 1216
-- 1600 A, and we apply this relation to make predictions. We test the method
on the HST spectra, and we find an average absolute flux error of 9%, with a
range 3 -- 30%, where individual predictions are systematically too low or too
high. We mention several ways in which the predictions might be improved.Comment: 17 pages, 4 figures, submitted to Ap
An investigation into manufacturing technology sourcing practices
This paper investigates the decisions that companies make when choosing the source of their manufacturing technology. It builds on previous research that has identified differences between the practices of US and Japanese manufacturing companies. A structured study of manufacturing technology sourcing practices at 14 US-based manufacturing companies is described. This research has confirmed that there is a trend in the companies studied to acquire manufacturing technology from sources external to their organisations. However, no formal processes are used to form these policies. When a rationale for this behaviour was sought, companies gave a series of reasons concerned with business focus, efficiency of technology acquisition, and the extent, defence and support of manufacturing capabilities
Copolymer sealant compositions and method for making
Condensation curable poly(fluoroorgano)siloxane-poly(silarylene)siloxane block copolymer compositions having a glass transition temperature not exceeding about -54.degree. C. and excellent solvent resistance have been found useful as sealants. Polyalkoxysilylorgano compounds, such as 1,4-bis[trimethoxysilyl(ethyl)]benzene have been found to be effective as cross-linkers
Copolymer sealant compositions and method for making
Condensation curable poly(fluoroorgano)siloxane-poly(silarylene)siloxane block copolymer compositions having a glass transition temperature not exceeding about -54.degree. C. and excellent solvent resistance have been found useful as sealants. Polyalkoxysilylorgano compounds, such as 1,4-bis[trimethoxysilyl(ethyl)]benzene have been found to be effective as cross-linkers
Rheological transitions in the middle crust:insights from Cordilleran metamorphic core complexes
High-strain mylonitic rocks in Cordilleran metamorphic
core complexes reflect ductile deformation in the middle crust, but in many
examples it is unclear how these mylonites relate to the brittle detachments
that overlie them. Field observations, microstructural analyses, and
thermobarometric data from the footwalls of three metamorphic core complexes
in the Basin and Range Province, USA (the Whipple Mountains, California; the
northern Snake Range, Nevada; and Ruby Mountains–East Humboldt Range,
Nevada), suggest the presence of two distinct rheological transitions in the
middle crust: (1) the brittle–ductile transition (BDT), which depends on
thermal gradient and tectonic regime, and marks the switch from discrete
brittle faulting and cataclasis to continuous, but still localized, ductile
shear, and (2) the localized–distributed transition, or LDT, a deeper, dominantly
temperature-dependent transition, which marks the switch from localized
ductile shear to distributed ductile flow. In this model, brittle normal
faults in the upper crust persist as ductile shear zones below the BDT in
the middle crust, and sole into the subhorizontal LDT at greater depths.<br><br>In metamorphic core complexes, the presence of these two distinct
rheological transitions results in the development of two zones of ductile
deformation: a relatively narrow zone of high-stress mylonite that is
spatially and genetically related to the brittle detachment, underlain by a
broader zone of high-strain, relatively low-stress rock that formed in the
middle crust below the LDT, and in some cases before the detachment was
initiated. The two zones show distinct microstructural assemblages,
reflecting different conditions of temperature and stress during
deformation, and contain superposed sequences of microstructures reflecting
progressive exhumation, cooling, and strain localization. The LDT is not
always exhumed, or it may be obscured by later deformation, but in the
Whipple Mountains, it can be directly observed where high-strain mylonites
captured from the middle crust depart from the brittle detachment along a
mylonitic front
The physics of blue crab larval recruitment in Delaware Bay: A model study
Recent studies have shown that the tidal-, wind- and buoyancy-driven surface currents govern the transport of blue crab (Callinectes sapidus) larvae within the coastal ocean and estuaries. Here, we develop a model of larval transport within Delaware Bay and the adjoining coastal ocean using a particle advection scheme coupled to a previously validated physical circulation model which includes realistic tidal forcing, bottom bathymetry, wind stress and river discharge. The coupled model is then used to quantify the effects of several mechanisms on larval transport and recruitment in this region and hindcast actual larval settlement for a four-year period.The model is run for the years 1989–1992 and compared with observations of larval settlement collected in the Broadkill River, a small tributary to Delaware Bay. It is able to reproduce all of the major observed recruitment events in 1990–1992, suggesting that larval recruitment is primarily driven by the physical mechanisms included in the model. Analysis of the modeled particle trajectories and the settlement data reveals that wind stress is the dominant mechanism in the determination of the timing of the settlement events, while horizontal diffusion and mortality determine the magnitude of the events. The model fails to agree with observations in 1989, indicating that small-scale physical events as well as larval behavior not reproduced in the numerical model can be important in larval settlement
An Inquiry into Pennsylvania\u27s Early Childhood Quality Rating and Improvement System
High-quality care in the earliest years of life has been shown to relate to positive developmental outcomes for children, including improved early academic skills, social-emotional competencies, and cognitive functioning. Unfortunately, the early care experiences of many children are not always high quality; rather, research suggests that high-quality care is the exception. The growing evidence relating quality care to improved learning outcomes, the variability in quality across care settings, and the failure of existing approaches to improve child care have led to a national call to enhance the quality of early care and education programs. In response to this call, states have created Quality Rating and Improvement Systems (QRISs)
An Inquiry into Pennsylvania’s Keystone STARS: Research Report
A team from the University of Pennsylvania was funded by the William Penn Foundation to conduct an inquiry of Keystone STARS. The goal of this inquiry was to provide a broad look at Keystone STARS to inform future revisions and evaluation of the system as part of Pennsylvania’s Race to the Top Early Learning Challenge grant (2013-2018). The inquiry focused on providing an overarching look at Keystone STARS with respect to three major areas and presents a detailed review of the data and findings for each of the three aspects: Child outcomes: examining the relations between Keystone STARS and children’s overall developmental competencies. Quality components: investigating the extent of evidence from theory, empirical research, and practitioner expertise linking each of the Keystone STARS quality components to child outcomes. Systems approach to rating quality and guiding improvements: examining overall features of the system that could be improved to enhance the effectiveness and efficiency of the system.
The authors conclude with an overview of the lessons learned and point to promising areas of reform for improving Keystone STARS for the children of Pennsylvania
Temporary amnesia from sleep loss: A framework for understanding consequences of sleep deprivation
Throughout its modern history, sleep research has been concerned with both the benefits of sleep and the deleterious impact of sleep disruption for cognition, behavior, and performance. When more specifically examining the impact of sleep on memory and learning, however, research has overwhelmingly focused on how sleep following learning facilitates memory, with less attention paid to how lack of sleep prior to learning can disrupt subsequent memory. Although this imbalance in research emphasis is being more frequently addressed by current investigators, there is a need for a more organized approach to examining the effect of sleep deprivation before learning. The present review briefly describes the generally accepted approach to analyzing effects of sleep deprivation on subsequent memory and learning by means of its effects on encoding. Then, we suggest an alternative framework with which to understand sleep loss and memory in terms of temporary amnesia from sleep loss (TASL). The review covers the well-characterized properties of amnesia arising from medial temporal lobe lesions and shows how the pattern of preserved and impaired aspects of memory in amnesia may also be appearing during sleep loss. The view of the TASL framework is that amnesia and the amnesia-like deficits observed during sleep deprivation not only affect memory processes but will also be apparent in cognitive processes that rely on those memory processes, such as decision-making. Adoption of the TASL framework encourages movement away from traditional explanations based on narrowly defined domains of memory functioning, such as encoding, and taking instead a more expansive view of how brain structures that support memory, such as the hippocampus, interact with higher structures, such as the prefrontal cortex, to produce complex cognition and behavioral performance, and how this interaction may be compromised by sleep disruption
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