Tracing the reactive melting of glass-forming silicate batches by in situ Na-23 NMR

Winter, Rudolf; Jones, A.R.; Florian, P.; Massiot, D., (2005) 'Tracing the reactive melting of glass-forming silicate batches by in situ Na-23 NMR', Journal of Physical Chemistry B 109(10) pp.4324-4332 RAE2008

Khirbet et-Tannur Excavation Records

The Khirbet et-Tannur Excavation Records document the 1938 excavation of a Nabataean temple. The excavation was directed by Nelson Glueck. The collection includes level books, excavation diaries, artifacts, and photographs. The collection is being processed. A finding aid for the document portion of the collection is available.

On the Intrinsic Locality Properties of Web Reference Streams

There has been considerable work done in the study of Web reference streams: sequences of requests for Web objects. In particular, many studies have looked at the locality properties of such streams, because of the impact of locality on the design and performance of caching and prefetching systems. However, a general framework for understanding why reference streams exhibit given locality properties has not yet emerged. In this work we take a first step in this direction, based on viewing the Web as a set of reference streams that are transformed by Web components (clients, servers, and intermediaries). We propose a graph-based framework for describing this collection of streams and components. We identify three basic stream transformations that occur at nodes of the graph: aggregation, disaggregation and filtering, and we show how these transformations can be used to abstract the effects of different Web components on their associated reference streams. This view allows a structured approach to the analysis of why reference streams show given properties at different points in the Web. Applying this approach to the study of locality requires good metrics for locality. These metrics must meet three criteria: 1) they must accurately capture temporal locality; 2) they must be independent of trace artifacts such as trace length; and 3) they must not involve manual procedures or model-based assumptions. We describe two metrics meeting these criteria that each capture a different kind of temporal locality in reference streams. The popularity component of temporal locality is captured by entropy, while the correlation component is captured by interreference coefficient of variation. We argue that these metrics are more natural and more useful than previously proposed metrics for temporal locality. We use this framework to analyze a diverse set of Web reference traces. We find that this framework can shed light on how and why locality properties vary across different locations in the Web topology. For example, we find that filtering and aggregation have opposing effects on the popularity component of the temporal locality, which helps to explain why multilevel caching can be effective in the Web. Furthermore, we find that all transformations tend to diminish the correlation component of temporal locality, which has implications for the utility of different cache replacement policies at different points in the Web.

CloudNeg: An autonomous multi issue negotiation system, with preference elicitation component, for trading cloud services

Cloud services provide its users with flexible resource provisioning. But in the current market, a user has to choose from a limited set of configurations at a fixed price. This paper presents an autonomous negotiation system termed CloudNeg for negotiating cloud services. CloudNeg provides buyers and sellers of cloud services with autonomous agents to negotiate on the specifications of a cloud instance, including price, on their behalf. These agents elicit their buyers’ time preferences and use them in negotiations. Further, this paper presents two artifacts: a negotiation algorithm and a prototype which together form CloudNeg.

Design history: exploring corporate communities

A design history is a narrative involving a multitude of social groups, interpretive flexibility, and eventual stabilization of shared understanding. Design history surfaces the practices that help shape and define engagements and can increase not only our theoretical understanding of what design is, but also our capacity to realize this understanding in practice. We use a design history perspective to examine how corporate technology initiatives establish and support open source communities and the crafting of relevant design practices that enable their advancement. We foster an evolving expression of design research that treats artifacts not as stable objects to be singularly evaluated, but as evolving systems contingent on historical trajectories.

Effectuation and its implications for socio-technical design science research in information systems

We study the implications of the effectuation concept for socio-technical artifact design as part of the design science research (DSR) process in information systems (IS). Effectuation logic is the opposite of causal logic. Ef-fectuation does not focus on causes to achieve a particular effect, but on the possibilities that can be achieved with extant means and resources. Viewing so-cio-technical IS DSR through an effectuation lens highlights the possibility to design the future even without set goals. We suggest that effectuation may be a useful perspective for design in dynamic social contexts leading to a more dif-ferentiated view on the instantiation of mid-range artifacts for specific local ap-plication contexts. Design science researchers can draw on this paper’s conclu-sions to view their DSR projects through a fresh lens and to reexamine their re-search design and execution. The paper also offers avenues for future research to develop more concrete application possibilities of effectuation in socio-technical IS DSR and, thus, enrich the discourse.

Comparative performance of multiview stereoscopic and mammographic display modalities for breast lesion detection.

PURPOSE: Mammography is known to be one of the most difficult radiographic exams to interpret. Mammography has important limitations, including the superposition of normal tissue that can obscure a mass, chance alignment of normal tissue to mimic a true lesion and the inability to derive volumetric information. It has been shown that stereomammography can overcome these deficiencies by showing that layers of normal tissue lay at different depths. If standard stereomammography (i.e., a single stereoscopic pair consisting of two projection images) can significantly improve lesion detection, how will multiview stereoscopy (MVS), where many projection images are used, compare to mammography? The aim of this study was to assess the relative performance of MVS compared to mammography for breast mass detection. METHODS: The MVS image sets consisted of the 25 raw projection images acquired over an arc of approximately 45 degrees using a Siemens prototype breast tomosynthesis system. The mammograms were acquired using a commercial Siemens FFDM system. The raw data were taken from both of these systems for 27 cases and realistic simulated mass lesions were added to duplicates of the 27 images at the same local contrast. The images with lesions (27 mammography and 27 MVS) and the images without lesions (27 mammography and 27 MVS) were then postprocessed to provide comparable and representative image appearance across the two modalities. All 108 image sets were shown to five full-time breast imaging radiologists in random order on a state-of-the-art stereoscopic display. The observers were asked to give a confidence rating for each image (0 for lesion definitely not present, 100 for lesion definitely present). The ratings were then compiled and processed using ROC and variance analysis. RESULTS: The mean AUC for the five observers was 0.614 +/- 0.055 for mammography and 0.778 +/- 0.052 for multiview stereoscopy. The difference of 0.164 +/- 0.065 was statistically significant with a p-value of 0.0148. CONCLUSIONS: The differences in the AUCs and the p-value suggest that multiview stereoscopy has a statistically significant advantage over mammography in the detection of simulated breast masses. This highlights the dominance of anatomical noise compared to quantum noise for breast mass detection. It also shows that significant lesion detection can be achieved with MVS without any of the artifacts associated with tomosynthesis.

Differential inhibition of human immunodeficiency virus type 1 in peripheral blood mononuclear cells and TZM-bl cells by endotoxin-mediated chemokine and gamma interferon production.

Bacterial lipopolysaccharide (endotoxin) is a frequent contaminant of biological specimens and is also known to be a potent inducer of beta-chemokines and other soluble factors that inhibit HIV-1 infection in vitro. Though lipopolysaccharide (LPS) has been shown to stimulate the production of soluble HIV-1 inhibitors in cultures of monocyte-derived macrophages, the ability of LPS to induce similar inhibitors in other cell types is poorly characterized. Here we show that LPS exhibits potent anti-HIV activity in phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMCs) but has no detectable anti-HIV-1 activity in TZM-bl cells. The anti-HIV-1 activity of LPS in PBMCs was strongly associated with the production of beta-chemokines from CD14-positive monocytes. Culture supernatants from LPS-stimulated PBMCs exhibited potent anti-HIV-1 activity when added to TZM-bl cells but, in this case, the antiviral activity appeared to be related to IFN-gamma rather than to beta-chemokines. These observations indicate that LPS stimulates PBMCs to produce a complex array of soluble HIV-1 inhibitors, including beta-chemokines and IFN-gamma, that differentially inhibit HIV-1 depending on the target cell type. The results also highlight the need to use endotoxin-free specimens to avoid artifacts when assessing HIV-1-specific neutralizing antibodies in PBMC-based assays.

3D refraction correction and extraction of clinical parameters from spectral domain optical coherence tomography of the cornea.

Capable of three-dimensional imaging of the cornea with micrometer-scale resolution, spectral domain-optical coherence tomography (SDOCT) offers potential advantages over Placido ring and Scheimpflug photography based systems for accurate extraction of quantitative keratometric parameters. In this work, an SDOCT scanning protocol and motion correction algorithm were implemented to minimize the effects of patient motion during data acquisition. Procedures are described for correction of image data artifacts resulting from 3D refraction of SDOCT light in the cornea and from non-idealities of the scanning system geometry performed as a pre-requisite for accurate parameter extraction. Zernike polynomial 3D reconstruction and a recursive half searching algorithm (RHSA) were implemented to extract clinical keratometric parameters including anterior and posterior radii of curvature, central cornea optical power, central corneal thickness, and thickness maps of the cornea. Accuracy and repeatability of the extracted parameters obtained using a commercial 859nm SDOCT retinal imaging system with a corneal adapter were assessed using a rigid gas permeable (RGP) contact lens as a phantom target. Extraction of these parameters was performed in vivo in 3 patients and compared to commercial Placido topography and Scheimpflug photography systems. The repeatability of SDOCT central corneal power measured in vivo was 0.18 Diopters, and the difference observed between the systems averaged 0.1 Diopters between SDOCT and Scheimpflug photography, and 0.6 Diopters between SDOCT and Placido topography.

Analytic expressions for the constitutive parameters of magnetoelectric metamaterials

Electromagnetic metamaterials are artificially structured media typically composed of arrays of resonant electromagnetic circuits, the dimension and spacing of which are considerably smaller than the free-space wavelengths of operation. The constitutive parameters for metamaterials, which can be obtained using full-wave simulations in conjunction with numerical retrieval algorithms, exhibit artifacts related to the finite size of the metamaterial cell relative to the wavelength. Liu showed that the complicated, frequency-dependent forms of the constitutive parameters can be described by a set of relatively simple analytical expressions. These expressions provide useful insight and can serve as the basis for more intelligent interpolation or optimization schemes. Here, we show that the same analytical expressions can be obtained using a transfer-matrix formalism applied to a one-dimensional periodic array of thin, resonant, dielectric, or magnetic sheets. The transfer-matrix formalism breaks down, however, when both electric and magnetic responses are present in the same unit cell, as it neglects the magnetoelectric coupling between unit cells. We show that an alternative analytical approach based on the same physical model must be applied for such structures. Furthermore, in addition to the intercell coupling, electric and magnetic resonators within a unit cell may also exhibit magnetoelectric coupling. For such cells, we find an analytical expression for the effective index, which displays markedly characteristic dispersion features that depend on the strength of the coupling coefficient. We illustrate the applicability of the derived expressions by comparing to full-wave simulations on magnetoelectric unit cells. We conclude that the design of metamaterials with tailored simultaneous electric and magnetic response-such as negative index materials-will generally be complicated by potentially unwanted magnetoelectric coupling. © 2010 The American Physical Society.

Hyperpolarized Xe MR imaging of alveolar gas uptake in humans.

BACKGROUND: One of the central physiological functions of the lungs is to transfer inhaled gases from the alveoli to pulmonary capillary blood. However, current measures of alveolar gas uptake provide only global information and thus lack the sensitivity and specificity needed to account for regional variations in gas exchange. METHODS AND PRINCIPAL FINDINGS: Here we exploit the solubility, high magnetic resonance (MR) signal intensity, and large chemical shift of hyperpolarized (HP) (129)Xe to probe the regional uptake of alveolar gases by directly imaging HP (129)Xe dissolved in the gas exchange tissues and pulmonary capillary blood of human subjects. The resulting single breath-hold, three-dimensional MR images are optimized using millisecond repetition times and high flip angle radio-frequency pulses, because the dissolved HP (129)Xe magnetization is rapidly replenished by diffusive exchange with alveolar (129)Xe. The dissolved HP (129)Xe MR images display significant, directional heterogeneity, with increased signal intensity observed from the gravity-dependent portions of the lungs. CONCLUSIONS: The features observed in dissolved-phase (129)Xe MR images are consistent with gravity-dependent lung deformation, which produces increased ventilation, reduced alveolar size (i.e., higher surface-to-volume ratios), higher tissue densities, and increased perfusion in the dependent portions of the lungs. Thus, these results suggest that dissolved HP (129)Xe imaging reports on pulmonary function at a fundamental level.

Phase II Archaeological Excavations at 99 Main Street, 18AP21 (Sign of the Whale), Annapolis, Maryland

Historical Annapolis Foundation (HAF) conducted terrestrial archaeological investigations at site 18AP21 in the city of Annapolis, Maryland. Excavations were carried out at this National Register site ostensibly as a Phase II project to evaluate the site and assess the need for further work. The site is at 99 Main Street in the center of downtown Annapolis, near the Annapolis waterfront. The project was carried out as part of the advanced work for the Annapolis History Center project, to be built in the adjoining buildings of 99 Main and 196 Green Streets. The buildings are the property of the Historic Annapolis Foundation and located in Maryland Research Unit 7. The excavations were undertaken by HAF, and funded by HAFF. The work was conducted for HAF and MHT, who holds an archaeological easement on the property. This preliminary phase of work included stratigraphic excavation of two testpit units. These two units revealed that the site of the existing 99 Main Street building was the location of three previous constructions. The current building at 99 Main Street, built in 1791, was preceded by an earlier brick dwelling, evidenced by a stout pier of bricks, which was attached to a wooden-sided structure that stood on a foundation of brick and stone. Ceramics indicate that these buildings date to the early-middle of the 18th century. A third structure of post-in-ground construction, evidenced by recovery of burned posts and wood fragments, likely existed prior to these, but evidence was scant. These excavations reveal that the site of 18AP21 holds potential for understanding Annapolis's early cultural developments, especially in the area of initial settlement and the origins of waterfront commerce. The assemblage of artifacts recovered includes a broad sample of common 18th century pottery such as creamware and Chinese export porcelain, and also includes some early colonial types such as tin-glazed earthenware and various red-bodied slipwares. The excavations do not provide conclusive evidence of the construction sequence. Consultation with MHT representatives indicates that further work at the site will likely be needed before modifications to the floor of the building can progress.

Three Hundred Years in Annapolis: Phase III Archaeological Investigations of the Anne Arundel County Courthouse Site (18AP63), Annapolis, Maryland

During the summer of 1994, Archaeology in Annapolis conducted archaeological investigations of the city block bounded by Franklin, South and Cathedral Streets in the city of Annapolis. This Phase III excavation was conducted as a means to identify subsurface cultural resources in the impact area associated with the proposed construction of the Anne Arundel County Courthouse addition. This impact area included both the upper and lower parking lots used by Courthouse employees. Investigations were conducted in the form of mechanical trenching and hand excavated units. Excavations in the upper lot area yielded significant information concerning the interior area of the block. Known as Bellis Court, this series of rowhouses was constructed in the late nineteenth century and was used as rental properties by African-Americans. The dwellings remained until the middle of the twentieth century when they were demolished in preparation for the construction of a Courthouse addition. Portions of the foundation of a house owned by William H. Bellis in the 1870s were also exposed in this area. Construction of this house was begun by William Nicholson around 1730 and completed by Daniel Dulany in 1732/33. It was demolished in 1896 by James Munroe, a Trustee for Bellis. Excavations in the upper lot also revealed the remains of a late seventeenth/early eighteenth century wood-lined cellar, believed to be part of the earliest known structure on Lot 58. After an initially rapid deposition of fill around 1828, this cellar was gradually covered with soil throughout the remainder of the nineteenth century. The fill deposit in the cellar feature yielded a mixed assemblage of artifacts that included sherds of early materials such as North Devon gravel-tempered earthenware, North Devon sgraffito and Northem Italian slipware, along with creamware, pearlware and whiteware. In the lower parking lot, numerous artifacts were recovered from yard scatter associated with the houses that at one time fronted along Cathedral Street and were occupied by African- Americans. An assemblage of late seventeenth century/early eighteenth century materials and several slag deposits from an early forge were recovered from this second area of study. The materials associated with the forge, including portions of a crucible, provided evidence of some of the earliest industry in Annapolis. Investigations in both the upper and lower parking lots added to the knowledge of the changing landscape within the project area, including a prevalence of open space in early periods, a surprising survival of impermanent structures, and a gradual regrading and filling of the block with houses and interior courts. Excavations at the Anne Arundel County Courthouse proved this to be a multi-component site, rich in cultural resources from Annapolis' Early Settlement Period through its Modern Period (as specified by Maryland's Comprehensive Historic Preservation Plan (Weissman 1986)). This report provides detailed interpretations of the archaeological findings of these Phase III investigations.

Archaeological Investigation at Slayton House, 18AP74, Annapolis, Maryland

Archaeological investigation at the Slayton House site in Annapolis revealed evidence of occupation of the lot since the early 18th century. The intact late 18th century ground surfaces on which John Ridout built the row houses, and subsequent changes in the landscape and use of the yard as work space in the 19th century were discovered. There was ample visible evidence of the early 20th century landscape and use of the yard as a pleasure garden when excavation was started. Deposits inside the house were quite disturbed, but there was evidence of the work done by the African Americans who lived there. A number of artifacts were found which may indicate the slaves and free African Americans were practicing African-related folk beliefs. No further investigations are recommended for the site. However, if severe or deep ground-disturbing activities were to take place on the property, they should be monitored by a qualified archaeologist.

Bayesian Gaussian Copula Factor Models for Mixed Data.

Gaussian factor models have proven widely useful for parsimoniously characterizing dependence in multivariate data. There is a rich literature on their extension to mixed categorical and continuous variables, using latent Gaussian variables or through generalized latent trait models acommodating measurements in the exponential family. However, when generalizing to non-Gaussian measured variables the latent variables typically influence both the dependence structure and the form of the marginal distributions, complicating interpretation and introducing artifacts. To address this problem we propose a novel class of Bayesian Gaussian copula factor models which decouple the latent factors from the marginal distributions. A semiparametric specification for the marginals based on the extended rank likelihood yields straightforward implementation and substantial computational gains. We provide new theoretical and empirical justifications for using this likelihood in Bayesian inference. We propose new default priors for the factor loadings and develop efficient parameter-expanded Gibbs sampling for posterior computation. The methods are evaluated through simulations and applied to a dataset in political science. The models in this paper are implemented in the R package bfa.