An extension of the characteristic angle method to the easy-plane spin-3/2 ferromagnet

The Characteristic Angle (CA) method [Lei Zhou and Ruibao Tao, J. Phys. A, {\bf 27} 5599] developed previously for the easy-plane spin-1 magnetic systems has been successfully extended to the spin-3/2 case. A compact form of the CA spin-3/2 operator transformation is given, then the ground state energy, the magnon dispersion relation and the spontaneous magnetization are discussed for an easy-plane spin-3/2 ferromagnet by using the CA method. Comparisons with the old theoretical methods are made in the end.Comment: LaTex formatted. To be published in the forthcoming issue of Physics Letters A (1996). 3 figures. Email address: [email protected]

Neutrino initiated cascades at mid and high altitudes in the atmosphere

High energy neutrinos play a very important role for the understanding of the origin and propagation of ultra high energy cosmic rays (UHECR). They can be produced as a consequence of the hadronic interactions suffered by the cosmic rays in the acceleration regions, as by products of the propagation of the UHECR in the radiation background and as a main product of the decay of super heavy relic particles. A new era of very large exposure space observatories, of which the JEM-EUSO mission is a prime example, is on the horizon which opens the possibility of neutrino detection in the highest energy region of the spectrum. In the present work we use a combination of the PYTHIA interaction code with the CONEX shower simulation package in order to produce fast one-dimensional simulations of neutrino initiated showers in air. We make a detail study of the structure of the corresponding longitudinal profiles, but focus our physical analysis mainly on the development of showers at mid and high altitudes, where they can be an interesting target for space fluorescence observatories.Comment: To appear in Astroparticle Physic

De Sitter Cosmic Strings and Supersymmetry

We study massive spinor fields in the geometry of a straight cosmic string in a de Sitter background. We find a hidden N=2 supersymmetry in the fermionic solutions of the equations of motion. We connect the zero mode solutions to the heat-kernel regularized Witten index of the supersymmetric algebra.Comment: Version similar to the one accepted by General Relativity and Gravitatio

Air fluorescence measurements in the spectral range 300-420 nm using a 28.5 GeV electron beam

Measurements are reported of the yield and spectrum of fluorescence, excited by a 28.5 GeV electron beam, in air at a range of pressures of interest to ultra-high energy cosmic ray detectors. The wavelength range was 300 - 420 nm. System calibration has been performed using Rayleigh scattering of a nitrogen laser beam. In atmospheric pressure dry air at 304 K the yield is 20.8 +/- 1.6 photons per MeV.Comment: 29 pages, 10 figures. Submitted to Astroparticle Physic

Heavy-tailed densities

The concept of heavy- or long-tailed densities (or distributions) has attracted much well-deserved attention in the literature. A quick search in Google using the keywords long-tailed statistics retrieves almost 12 million items. The concept has become a pillar of the theory of extremes, and through its connection with outlier-prone distributions, long-tailed distributions also play a central role in the theory of robustness. The concept of tail heaviness is by now ubiquitous, appearing in a diverse set of disciplines that includes: economics, communications, atmospheric sciences, climate modeling, social sciences, physics, modeling of complex systems, etc. Nevertheless, the precise meaning of ‘long-’ or ‘heavy tails’ remains somewhat elusive. Thus, in a substantial portion of the early literature, long-tailednessmeant that the underlying distributionwas capable of producing anomalous observations in the sense that they were ‘too far’ from themain body of observations. Implicit in these informal definitions was the notion that any distribution that behaved that way had to do so because its tails were longer than those of the normal distribution. This paper discusses tail orderings and several approaches for the classification of probability distributions according to tail heaviness. It is concluded that an approach based on the limiting behavior of the residual life function, and its corresponding characterizations based on functions of regular variation and asymptotic distribution of extreme spacings, provides the more natural and illuminating concepts of tail behavior

Production and characterization of carbamazepine nanocrystals by electrospraying for continuous pharmaceutical manufacturing

In this paper, an electrospray technique followed by annealing at high temperatures was developed to produce nanocrystals of carbamazepine (CBZ), a poorly water-soluble drug, for continuous pharmaceutical manufacturing process. Electrospraying solutions of CBZ in methanol obeys the expected scaling law of current, which is I ∼ Q[superscript 1/2] (I, electrical current; Q, flow rate), for liquids with sufficiently high conductivity and viscosity. Lower flow rates during electrospraying were preferred to produce smaller diameters of monodisperse, dense CBZ nanoparticles. CBZ nanoparticles were predominantly amorphous immediately after electrospraying. Crystallization of CBZ nanoparticles was accelerated by annealing at high temperatures. CBZ nanocrystals with the most stable polymorph, form III, were obtained by annealing at 90°C, which is above the transition temperature, 78°C, for the enantiotropic CBZ form III and form I. The solubility and dissolution rates of CBZ nanocrystals increased significantly as compared with those of CBZ bulk particles. Therefore, electrospray technology has the potential to produce pharmaceutical dosage forms with enhanced bioavailability and can readily be integrated in a continuous pharmaceutical manufacturing process.Novartis-MIT Center for Continuous Manufacturin

Radiomics-Based Computed Tomography Urogram Approach for the Prediction of Survival and Recurrence in Upper Urinary Tract Urothelial Carcinoma

Upper tract urothelial carcinoma (UTUC) is a rare and aggressive malignancy with a poor prognosis. The accurate prediction of survival and recurrence in UTUC is crucial for effective risk stratification and guiding therapeutic decisions. Models combining radiomics and clinicopathological data features derived from computed tomographic urograms (CTUs) can be a way to predict survival and recurrence in UTUC. Thus, preoperative CTUs and clinical data were analyzed from 106 UTUC patients who underwent radical nephroureterectomy. Radiomics features were extracted from segmented tumors, and the Least Absolute Shrinkage and Selection Operator (LASSO) method was used to select the most relevant features. Multivariable Cox models combining radiomics features and clinical factors were developed to predict the survival and recurrence. Harrell’s concordance index (C-index) was applied to evaluate the performance and survival distribution analyses were assessed by a Kaplan–Meier analysis. The significant outcome predictors were identified by multivariable Cox models. The combined model achieved a superior predictive accuracy (C-index: 0.73) and higher recurrence prediction (C-index: 0.84). The Kaplan–Meier analysis showed significant differences in the survival (p < 0.0001) and recurrence (p < 0.002) probabilities for the combined datasets. The CTU-based radiomics models effectively predicted survival and recurrence in the UTUC patients, and enhanced the prognostic performance by combining radiomics features with clinical factors

Microwave and Quantum Magnetics

Contains research objectives and reports on seven research projects.U.S. Army Research Office (Contract DAAG29-81-K-0126)National Science Foundation (Grant 8008628-DAR)Joint Services Electronics Program (Contract DAAG29-80-C-0104)National Institutes of Health (Grant 1 PO1 CA31303-01

Working toward exposure thresholds for blast-induced traumatic brain injury: thoracic and acceleration mechanisms

Research in blast-induced lung injury resulted in exposure thresholds that are useful in understanding and protecting humans from such injury. Because traumatic brain injury (TBI) due to blast exposure has become a prominent medical and military problem, similar thresholds should be identified that can put available research results in context and guide future research toward protecting warfighters as well as diagnosis and treatment. At least three mechanical mechanisms by which the blast wave may result in brain injury have been proposed - a thoracic mechanism, head acceleration and direct cranial transmission. These mechanisms need not be mutually exclusive. In this study, likely regions of interest for the first two mechanisms based on blast characteristics (positive pulse duration and peak effective overpressure) are developed using available data from blast experiments and related studies, including behind-armor blunt trauma and ballistic pressure wave studies. These related studies are appropriate to include because blast-like pressure waves are produced that result in neurological effects like those caused by blast. Results suggest that injury thresholds for each mechanism are dependent on blast conditions, and that under some conditions, more than one mechanism may contribute. There is a subset of blast conditions likely to result in TBI due to head acceleration and/or a thoracic mechanism without concomitant lung injury. These results can be used to guide experimental designs and compare additional data as they become available. Additional data are needed before actual probabilities or severity of TBI for a given exposure can be described.Comment: 11 page