Short-term effects of intratracheal installations of yttrium barium copper oxide

Inhalation exposures to the new high-temperature ({Tc}) superconductor (SC) materials can occur during manufacturing and fabrication processes. In this exploratory study, we examined the pulmonary response to the deposition of an yttrium barium copper oxide SC powder. Groups of Sprague-Dawley rats were intratracheally instilled with either 10 mg or 20 mg of SC in phosphate-buffered saline (PBS) or with PBS only. The animals were sacrificed 60 days later for histopathologic assessments of their lungs. Lung lesions in the 10-mg SC group were found mainly in alveolar ducts and proximal alveoli. The lesions consisted of variably sized foci of interstitial thickening involving accumulations of macrophages. These interstitial aggregates were often times centered around one or more extracellular crystals, which, presumably, were retained SC product. Trichome stains also demonstrated the presence of fibrosis in the walls of alveoli surrounding the granulomas. Similar interstitial-macrophage accumulations and fibrosis were observed in rats instilled with 20 mg of SC. However, alveolus like structures lined by ciliated cuboidal epithelium near interstitial granulomas were additionally found in the lungs of some of the animals in this latter group. These results suggest SC material of the yttrium barium copper oxide type may represent a potential exposure hazard to the lung

ROCker Models for Reliable Detection and Typing of Short-Read Sequences Carrying beta-Lactamase Genes

Identification of genes encoding beta-lactamases (BLs) from short-read sequences remains challenging due to the high frequency of shared amino acid functional domains and motifs in proteins encoded by BL genes and related non-BL gene sequences. Divergent BL homologs can be frequently missed during similarity searches, which has important practical consequences for monitoring antibiotic resistance. To address this limitation, we built ROCker models that targeted broad classes (e.g., class A, B, C, and D) and individual families (e.g., TEM) of BLs and challenged them with mock 150-bp- and 250-bp-read data sets of known composition. ROCker identifies most-discriminant bit score thresholds in sliding windows along the sequence of the target protein sequence and hence can account for nondiscriminative domains shared by unrelated proteins. BL ROCker models showed a 0% false-positive rate (FPR), a 0% to 4% false-negative rate (FNR), and an up-to-50-fold-higher F1 score [2 x precision x recall/(precision + recall)] compared to alternative methods, such as similarity searches using BLASTx with various e-value thresholds and BL hidden Markov models, or tools like DeepARG, ShortBRED, and AMRFinder. The ROCker models and the underlying protein sequence reference data sets and phylogenetic trees for read placement are freely available through http://enve-omics.ce.gatech.edu/data/rocker-bla. Application of these BL ROCker models to metagenomics, metatranscriptomics, and high-throughput PCR gene amplicon data should facilitate the reliable detection and quantification of BL variants encoded by environmental or clinical isolates and microbiomes and more accurate assessment of the associated public health risk, compared to the current practice. IMPORTANCE Resistance genes encoding beta-lactamases (BLs) confer resistance to the widely prescribed antibiotic class beta-lactams. Therefore, it is important to assess the prevalence of BL genes in clinical or environmental samples for monitoring the spreading of these genes into pathogens and estimating public health risk. However, detecting BLs in short-read sequence data is technically challenging. Our ROCker model-based bioinformatics approach showcases the reliable detection and typing of BLs in complex data sets and thus contributes toward solving an important problem in antibiotic resistance surveillance. The ROCker models developed substantially expand the toolbox for monitoring antibiotic resistance in clinical or environmental settings

Preparation of fiber reinforced titanium diboride and boron carbide composite bodies

A process is described for uniformly infiltrating woven carbon cloth with either titanium diboride or boron carbide at reduced pressure (15 to 25 torr). The effects of deposition temperature on the uniformity of penetration and on coating rate are described for temperatures from 750 to 1000/sup 0/C and deposit loadings from 20 to 43 vol. %. For the boron carbides, boron composition is discussed and evidence is presented suggesting that propene is the dominant rate controlling reactant

A Model for the Stray Light Contamination of the UVCS Instrument on SOHO

We present a detailed model of stray-light suppression in the spectrometer channels of the Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO spacecraft. The control of diffracted and scattered stray light from the bright solar disk is one of the most important tasks of a coronagraph. We compute the fractions of light that diffract past the UVCS external occulter and non-specularly pass into the spectrometer slit. The diffracted component of the stray light depends on the finite aperture of the primary mirror and on its figure. The amount of non-specular scattering depends mainly on the micro-roughness of the mirror. For reasonable choices of these quantities, the modeled stray-light fraction agrees well with measurements of stray light made both in the laboratory and during the UVCS mission. The models were constructed for the bright H I Lyman alpha emission line, but they are applicable to other spectral lines as well.Comment: 19 pages, 5 figures, Solar Physics, in pres

Multiwavelength Study on Solar and Interplanetary Origins of the Strongest Geomagnetic Storm of Solar Cycle 23

We study the solar sources of an intense geomagnetic storm of solar cycle 23 that occurred on 20 November 2003, based on ground- and space-based multiwavelength observations. The coronal mass ejections (CMEs) responsible for the above geomagnetic storm originated from the super-active region NOAA 10501. We investigate the H-alpha observations of the flare events made with a 15 cm solar tower telescope at ARIES, Nainital, India. The propagation characteristics of the CMEs have been derived from the three-dimensional images of the solar wind (i.e., density and speed) obtained from the interplanetary scintillation data, supplemented with other ground- and space-based measurements. The TRACE, SXI and H-alpha observations revealed two successive ejections (of speeds ~350 and ~100 km/s), originating from the same filament channel, which were associated with two high speed CMEs (~1223 and ~1660 km/s, respectively). These two ejections generated propagating fast shock waves (i.e., fast drifting type II radio bursts) in the corona. The interaction of these CMEs along the Sun-Earth line has led to the severity of the storm. According to our investigation, the interplanetary medium consisted of two merging magnetic clouds (MCs) that preserved their identity during their propagation. These magnetic clouds made the interplanetary magnetic field (IMF) southward for a long time, which reconnected with the geomagnetic field, resulting the super-storm (Dst_peak=-472 nT) on the Earth.Comment: 24 pages, 16 figures, Accepted for publication in Solar Physic

Interchange Slip-Running Reconnection and Sweeping SEP Beams

We present a new model to explain how particles (solar energetic particles; SEPs), accelerated at a reconnection site that is not magnetically connected to the Earth, could eventually propagate along the well-connected open flux tube. Our model is based on the results of a low-beta resistive magnetohydrodynamics simulation of a three-dimensional line-tied and initially current-free bipole, that is embedded in a non-uniform open potential field. The topology of this configuration is that of an asymmetric coronal null-point, with a closed fan surface and an open outer spine. When driven by slow photospheric shearing motions, field lines, initially fully anchored below the fan dome, reconnect at the null point, and jump to the open magnetic domain. This is the standard interchange mode as sketched and calculated in 2D. The key result in 3D is that, reconnected open field lines located in the vicinity of the outer spine, keep reconnecting continuously, across an open quasi-separatrix layer, as previously identified for non-open-null-point reconnection. The apparent slipping motion of these field lines leads to form an extended narrow magnetic flux tube at high altitude. Because of the slip-running reconnection, we conjecture that if energetic particles would be traveling through, or be accelerated inside, the diffusion region, they would be successively injected along continuously reconnecting field lines that are connected farther and farther from the spine. At the scale of the full Sun, owing to the super-radial expansion of field lines below 3 solar radii, such energetic particles could easily be injected in field lines slipping over significant distances, and could eventually reach the distant flux tube that is well-connected to the Earth

Phenomenology As Philosophy and Method

Phenomenology is a philosophical movement that approaches the study of human beings and their culture differently from the logical positivist model used in the natural sciences and in special education. phenomenologists view the application of the logical positivist model to the study of human beings as inappropriate because the model does not address the uniqueness of human life. in this article, the theroetical assumptions and methodological orientations of phenomenology are discussed, followed by their applications to ways of doing research in special education.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68638/2/10.1177_074193259501600305.pd

Recent Advances in Understanding Particle Acceleration Processes in Solar Flares

We review basic theoretical concepts in particle acceleration, with particular emphasis on processes likely to occur in regions of magnetic reconnection. Several new developments are discussed, including detailed studies of reconnection in three-dimensional magnetic field configurations (e.g., current sheets, collapsing traps, separatrix regions) and stochastic acceleration in a turbulent environment. Fluid, test-particle, and particle-in-cell approaches are used and results compared. While these studies show considerable promise in accounting for the various observational manifestations of solar flares, they are limited by a number of factors, mostly relating to available computational power. Not the least of these issues is the need to explicitly incorporate the electrodynamic feedback of the accelerated particles themselves on the environment in which they are accelerated. A brief prognosis for future advancement is offered.Comment: This is a chapter in a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011

Sources of SEP Acceleration during a Flare-CME Event

A high-speed halo-type coronal mass ejection (CME), associated with a GOES M4.6 soft X-ray flare in NOAA AR 0180 at S12W29 and an EIT wave and dimming, occurred on 9 November 2002. A complex radio event was observed during the same period. It included narrow-band fluctuations and frequency-drifting features in the metric wavelength range, type III burst groups at metric--hectometric wavelengths, and an interplanetary type II radio burst, which was visible in the dynamic radio spectrum below 14 MHz. To study the association of the recorded solar energetic particle (SEP) populations with the propagating CME and flaring, we perform a multi-wavelength analysis using radio spectral and imaging observations combined with white-light, EUV, hard X-ray, and magnetogram data. Velocity dispersion analysis of the particle distributions (SOHO and Wind in situ observations) provides estimates for the release times of electrons and protons. Our analysis indicates that proton acceleration was delayed compared to the electrons. The dynamics of the interplanetary type II burst identify the burst source as a bow shock created by the fast CME. The type III burst groups, with start times close to the estimated electron release times, trace electron beams travelling along open field lines into the interplanetary space. The type III bursts seem to encounter a steep density gradient as they overtake the type II shock front, resulting in an abrupt change in the frequency drift rate of the type III burst emission. Our study presents evidence in support of a scenario in which electrons are accelerated low in the corona behind the CME shock front, while protons are accelerated later, possibly at the CME bow shock high in the corona.Comment: Solar Physics, November 2007, in pres