The diffuse X-ray spectrum from 14-200 keV as measured on OSO-5

The measurement of energy spectrum of the diffuse component of cosmic X-ray flux made on the OSO-5 spacecraft is described. The contributions to the total counting rate of the actively shielded X-ray detector are considered in some detail and the techniques used to eliminate the non-cosmic components are described. Positive values for the cosmic flux are obtained in seven energy channels between 14 and 200 keV and two upper limits are obtained between 200 and 254 keV. The results can be fitted by a power law spectrum. A critical comparison is made with the OSO-3 results. Conclusions show that the reported break in the energy spectrum at 40 keV is probably produced by an erroneous correction for the radioactivity induced in the detector on each passage through the intense charged particle fluxes in the South Atlantic anomaly

A Time-Space Tradeoff for Triangulations of Points in the Plane

In this paper, we consider time-space trade-offs for reporting a triangulation of points in the plane. The goal is to minimize the amount of working space while keeping the total running time small. We present the first multi-pass algorithm on the problem that returns the edges of a triangulation with their adjacency information. This even improves the previously best known random-access algorithm

Intima-Media Thickness: Setting a Standard for a Completely Automated Method of Ultrasound Measurement

The intima – media thickness (IMT) of the common carotid artery is a widely used clinical marker of severe cardiovascular diseases. IMT is usually manually measured on longitudinal B-Mode ultrasound images. Many computer-based techniques for IMT measurement have been proposed to overcome the limits of manual segmentation. Most of these, however, require a certain degree of user interaction. In this paper we describe a new completely automated layers extraction (CALEXia) technique for the segmentation and IMT measurement of carotid wall in ultrasound images. CALEXia is based on an integrated approach consisting of feature extraction, line fitting, and classification that enables the automated tracing of the carotid adventitial walls. IMT is then measured by relying on a fuzzy K-means classifier. We tested CALEXia on a database of 200 images. We compared CALEXia performances to those of a previously developed methodology that was based on signal analysis (CULEXsa). Three trained operators manually segmented the images and the average profiles were considered as the ground truth. The average error from CALEXia for lumen – intima (LI) and media – adventitia (MA) interface tracings were 1.46 ± 1.51 pixel (0.091 ± 0.093 mm) and 0.40 ± 0.87 pixel (0.025 ± 0.055 mm), respectively. The corresponding errors for CULEXsa were 0.55 ± 0.51 pixels (0.035 ± 0.032 mm) and 0.59 ± 0.46 pixels (0.037 ± 0.029 mm). The IMT measurement error was equal to 0.87 ± 0.56 pixel (0.054 ± 0.035 mm) for CALEXia and 0.12 ± 0.14 pixel (0.01 ± 0.01 mm) for CULEXsa. Thus, CALEXia showed limited performance in segmenting the LI interface, but outperformed CULEXsa in the MA interface and in the number of images correctly processed (10 for CALEXia and 16 for CULEXsa). Based on two complementary strategies, we anticipate fusing them for further IMT improvements

Reconsidering the Reality of Southeastern Mesoamerica: Continuity, Diversity, and Inter-Valley Interaction in Western Honduras

The late fifth century AD was a time of rapid transformation in non-­‐Maya southeastern Mesoamerica. From this time forward, the landscape of western Honduras would become filled with increasingly complex polities and rising populations. So too is there evidence for a distinctive change in material culture, such as the development of widely shared regional polychrome ceramic traditions and the stabilization of obsidian exchange networks. Arguably, more than any other period in prehistory, it is during the Late Classic that a unique cultural identity emerges from this part of southeastern Mesoamerica. In this paper we seek to answer the question, can we characterize the diverse peoples and communities of Late Classic western Honduras as belonging to a culture area of shared affiliation and concordant identities, or is “southeastern Mesoamerica” nothing more than a geographic designation, which encompasses a diversity of strategies just different enough to defy uniform classification? To address this question we place the findings of our own research in the broader context of the long-­‐term research projects conducted by our colleagues since the 1980s. In particular, we emphasize the inter-­‐valley interactions among these polities to illuminate the shared and divergent paths taken by these communities during this period

Documentation of the data analysis system for the gamma ray monitor aboard OSO-H

The programming system is presented which was developed to prepare the data from the gamma ray monitor on OSO-7 for scientific analysis. The detector, data, and objectives are described in detail. Programs presented include; FEEDER, PASS-1, CAL1, CAL2, PASS-3, Van Allen Belt Predict Program, Computation Center Plot Routine, and Response Function Programs

MR coil sensitivity inhomogeneity correction for plaque characterization in carotid arteries

We are involved in a comprehensive program to characterize atherosclerotic disease using multiple MR images having different contrast mechanisms (T1W, T2W, PDW, magnetization transfer, etc.) of human carotid and animal model arteries. We use specially designed intravascular and surface array coils that give high signal-to-noise but suffer from sensitivity inhomogeneity. With carotid surface coils, challenges include: (1) a steep bias field with an 80% change; (2) presence of nearby muscular structures lacking high frequency information to distinguish bias from anatomical features; (3) many confounding zero-valued voxels subject to fat suppression, blood flow cancellation, or air, which are not subject to coil sensitivity; and (4) substantial noise. Bias was corrected using a modification of the adaptive fuzzy c-mean method reported by Pham et al. (IEEE TMI, 18:738-752), whereby a bias field modeled as a mechanical membrane was iteratively improved until cluster means no longer changed. Because our images were noisy, we added a noise reduction filtering step between iterations and used approximate to5 classes. In a digital phantom having a bias field measured from our MR system, variations across an area comparable to a carotid artery were reduced from 50% t

Bilateral temporal spinous projections overshadowing the sphenoidal spines: an anatomical and radiological evaluation

The infratemporal fossa has traditionally been described as a post-maxillary space, which is open below, to the rear and laterally. The most reliable osseous landmarks of the infratemporal and parapharyngeal spaces are the pterygoid and styloid processes and the sphenoidal spine. In the present study the skull exhibited the normal sphenoidal spines along with a prominent spinous projection emanating bilaterally from the tympanic plate of the temporal bone. The objective of the present paper is to report an anatomical and radiological evaluation of the sphenoidal spines coexistent with bilateral temporal spinous projections. Additionally, the topographical relationship of this osseous variation is discussed with particular reference to neurovascular structures. Unduly prominent temporal spinous projections may cause obstruction, thus reducing the operative field. The anatomical variations relating to bony and vascular structures in this region are of paramount importance to neurosurgeons and otorhinolaryngologists

Designing Minimum Cost Nonblocking Communication Networks

This paper addresses the problem of topological design of ATM (and similar) communication networks. We formulate the problem from a worst-case point of view, seeking network desings that, subject to specified traffic constraints, are nonblocking for point-to-point and multicast virtual circuits. Within this model we give various conditions under which star networks are optimal or near-optimal. These conditions are approximately satisfied in many common situations making the results of practical significance. An important consequence of these results is that, where they apply, there is no added cost for nonblocking multicast communication, relative to networks that are nonblocking for point-to-point traffic only