bluuebunny/crossref_metadata_2025 huggingface dataset:
Sci‐Fri AM: YIS‐08: Prototype fan beam optical computed tomography scanner for three‐dimensional dose verification in radiation therapy
Authors: Rudko D , Wells D , Jirasek A
Published: July 2008

A prototype, rapid, high precision fan beam optical computed tomography (OptCT) scanner for three‐dimensional polymer gel dosimetry of complex radiotherapy protocols has been developed. The scanner employs a sixty degree fan beam of 543 nm laser light to interrogate irradiated gel samples up to 19 cm in cross‐sectional diameter. Rapid data acquisition with minimal scattered light and minimal refraction and reflection artefacts is achieved with the unique radial design of the front and back apertures of the index matching medium tank, concentric arrangement of a CNC machined collimator and five photodiode detector arrays for light detection. Characteristics of the scanner include: an SNR of optical absorbance in light field projections of up to 100:1; SNR of optical absorbance in transmission projections of up to 92:1 for phantoms with absorbances ranging from 0.1 to 1.0 and a spatial resolution of 0.25 mm. OptCT dose maps extracted from normoxic NIPAM polymer gels irradiated with (a) a rectangular 3×3 cm2 field, (b) a 4‐field wedged treatment and (c) a C‐shaped IMRT plan are examined and compared to the Eclipse TPS. For these treatments, dose resolution is examined in steep and moderate dose gradient regions using dose difference and gamma function metrics. The effect of different OptCT reconstruction parameters on ring and streaking artefacts is also demonstrated.
Sci‐Fri AM: YIS‐10: Development of a flat panel detector with avalanche gain for low‐dose x‐ray imaging
Authors: Wronski MM , Reznik A , Rowlands JA , Zhao W , Segui JA
Published: July 2008

Digital flat panel detectors are increasingly being used in radiography and fluoroscopy. The imaging performance of current systems, however, is compromised by electronic noise at the low X‐ray exposures employed in fluoroscopy and low‐dose radiography. In other words, current flat panel detectors are not quantum noise limited at these low radiation exposures. There is thus a need to develop an imaging detector with the high sensitivity of an X‐ray image intensifier and the inherent advantages of a solid‐state flat panel detector. Towards this end, we have developed and characterized a novel solid‐state device capable of providing very high avalanche gains and an excellent temporal response. The device which is based on the amorphous photoconductor a‐Se, is scalable (i.e. can be manufactured in large areas), can overcome electronic noise even at the lowest X‐ray exposures used in diagnostic imaging (0.1 μR/frame at the detector) and has a very low level of dark current. Here, we investigate the gain and temporal characteristics of this device and discuss its applicability for low exposure X‐ray imaging as well as the effects of avalanche gain on the detective quantum efficiency. Coupled to a high‐resolution structured CsI X‐ray scintillator and a thin film transistor array, this device should provide a true solid‐state alternative to the X‐ray image intensifier, which is both robust and cost‐effective. This should open the door to dose‐efficient flat panel imagers for radiography and fluoroscopy as well as a number of other demanding medical imaging applications.
Sci‐Sat AM(1): Imaging‐03: On‐line dynamic contrast enhanced cone‐beam CT for measuring
Authors: Tang Q , Kim S , Clarkson R , Cho Y‐B , Moseley D , Yeung I
Published: July 2008

We propose a novel on‐line functional imaging method with which tumor microenvironment can be quantified at the treatment unit. It is an X‐ray contrast enhanced method based the (kv) cone beam CT (CBCT) platform and it promises to provide a surrogate measurement of tumor perfusion. The method was tested with 6 rabbits implanted with VX2 tumor. The technique involves a baseline CBCT followed by a contrast enhanced CBCT synchronized with contrast injection. The scan time for each CBCT is approximately 2 minutes during which a set of projections are acquired. The conventional reconstruction approach of contrast enhanced CBCT will give a single volumetric image with no temporal signature. On the other hand, the proposed technique makes use of a mathematical expression to parameterize the wash‐in and wash‐out behavior of contrast uptake in each voxel. Based on the projection data, the new method uses non‐linear optimization to solve for the parameters describing the dynamic characteristics of injected contrast with which tumor perfusion can be derived. In our rabbit study, dynamic contrast enhanced images were reconstructed with the CBCT projections by the proposed method. Results show that the estimated contrast enhancement with the proposed CBCT method is in excellent agreement with the measured enhancement by CT. The proposed CBCT method is sensitive for detecting changes in the tumor microenvironment as a result of radiation treatment.
Aggressive angiomyxoma of the lung
Authors: Choi Y D , Kim J H , Nam J H , Choi C , Na K J , Song S Y
Published: July 2008

Aggressive angiomyxoma (AAM) is a rare mesenchymal neoplasm that usually occurs in the pelvic–perineal region. Only two cases of AAM occurring outside this region have been reported. The case of AAM reported here originated from lung. A 70-year-old woman was admitted for evaluation of an incidentally detected pulmonary mass on chest radiography. Tumour resection under the thoracoscopy was performed. Pathological examination revealed microscopical features that were characteristic of AAM. The features were oval- to spindle-shaped tumour cells in a myxoid stroma, hyalinised thick vessels, and characteristic immunophenotype. The differential diagnosis of AAM and other mesenchymal neoplasms of lung is also discussed.
Todd, Faraday and the electrical basis of brain activity
Authors: Reynolds Edward
Published: July 2008

The origins of our understanding of brain electricity and electrical discharges in epilepsy can be traced to Robert Bentley Todd (1809–60). Todd was influenced by his contemporary in London, Michael Faraday (1791–1867), who in the 1830s and 1840s was laying the foundations of our modern understanding of electromagnetism. Todd’s concept of nervous polarity, generated in nerve vesicles and transmitted in nerve fibres (neurons in later terminology), was confirmed a century later by the Nobel Prize-winning work of Hodgkin and Huxley, who demonstrated the ionic basis of neuro-transmission, involving the same ions which had had been discovered by Faraday’s mentor, Sir Humphry Davy (1778–1829).
Migraine prevention
Authors: Dodick D W , Silberstein S D
Published: July 2008

Preventive medications reduce migraine frequency and severity, and improve migraine-specific quality of life. Recent evidence also suggests that these same medications enhance the patient’s response to acute migraine therapies, and may also reduce the likelihood of developing chronic daily headache. However, many patients who should receive or be offered preventive treatment are not. Most patients can be successfully managed when patient and physician expectations are realistic and aligned, the selection of preventive medications is individualised, and the initiation and titration strategy is appropriate and carefully followed. Rational combinations of preventive medications may also be useful. This review provides an evidence and experience-based approach to the preventive treatment of migraine.
When the patient fails to respond to treatment: TIAs that go on, and on
Authors: Hankey G J
Published: July 2008

Most transient ischaemic attacks (TIAs) stop, with or without treatment, but some are followed by stroke within days or longer. But if the TIAs do not stop then the diagnosis must be reviewed (are they really TIAs or could they be migraine or epilepsy?), and if they are TIAs, what are they caused by (atherothromboembolism, embolism from the heart, etc)? With this information, both the medical and any surgical treatment can be optimised, even though one must accept that the randomised controlled trials mostly have not addressed the particular issue of continuing TIAs.
European Handbook of Neurological Management
Authors: Hankey G J
Published: July 2008

Edited by Richard Hughes, Michael Brainin, Nils Erik Gilhus. Published by Blackwell Publishing, £120. ISBN 1-4051-3050-4
Contrasting predation risks presented by introduced brown trout and native common river galaxias in New Zealand streams
Authors: McIntosh Angus R. , Townsend Colin R.
Published: July 2008

Alterations in the predation risk affecting macroinvertebrates in streams of the Taieri River system of New Zealand were assessed following the replacement of native common river galaxias (Galaxias vulgaris) in many sites by introduced brown trout (Salmo trutta). In laboratory channels, galaxias foraged on mayfly nymphs from benthic positions; they searched for prey at night but stayed in cover during the day except when attacking prey. Trout foraged from positions in the water column during day and night. There were no diel differences in foraging by galaxias but trout had higher reaction distances and consumed more during the day. No diel pattern was found in trout stomach contents in the field, probably because of a nocturnal increase in prey availability. Trout and galaxias populations in the field consumed similar biomasses of aquatic prey. However, these experiments indicate there have been subtle changes in the predation regime. Trout relied on visual cues to capture prey so predation risk was higher during the day and larger prey items were more at risk. In comparison, galaxias relied more on mechanical cues to capture prey and predation risk was similar during day and night.
Effects of habitat on settlement, growth, and postsettlement survival of Atlantic cod (Gadus morhua)
Authors: Tupper M. , Boutilier R. G.
Published: July 2008

Settlement and growth of age 0+ cod were monitored using snorkel and self-contained underwater breathing apparatus (SCUBA) in four distinct habitat types (sand, seagrass, cobble, and rock reef) in St. Margaret's Bay, Nova Scotia. Newly settled cod were marked with acrylic dye, allowing repeated visual length estimates of individual fish. Settlement of cod did not differ between habitat types, but postsettlement survival and subsequent juvenile densities were higher in more structurally complex habitats. These differences appear to be due to increased shelter availability and decreased predator efficiency in structurally complex habitats. Growth rate was highest in seagrass beds, while the efficiency of cod predators was lowest and cod survival was highest on rocky reefs and cobble bottoms. Thus, trade-offs occur between energy gain and predation risk. In St. Margaret's Bay, the population structure of Atlantic cod may be less influenced by patterns of larval supply than by postsettlement processes such as habitat-specific growth and mortality.
Spatial scales of variability in cod recruitment in the North Atlantic
Authors: Myers R. A. , Mertz G. , Barrowman N. J.
Published: July 2008

We reexamine the hypothesis that there are large-scale (thousands of kilometres) patterns of recruitment of Atlantic cod (Gadus morhua) in the North Atlantic. Previous analyses have used sequential population analysis to reconstruct population histories; however, these methods are subject to a variety of biases and rely on the accuracy of commercial catch-at-age data. Several different studies have arrived at conflicting interpretations using virtually the same data. Here we analyze alternative data from research surveys using statistical methods that explicitly account for estimation error and we also employ detrended sequential population analysis. We conclude that the spatial scale of recruitment correlations generally does not exceed 500 km.
Polymorphic microsatellite loci from Atlantic salmon (Salmo salar): genetic differentiation of North American and European populations
Authors: McConnell Stewart K. , O'Reilly Patrick , Hamilton Lorraine , Wright Jonathan M. , Bentzen Paul
Published: July 2008

Atlantic salmon populations show low levels of genetic differentiation relative to other salmonid species, when surveyed by allozymes, and with mitochondrial DNA and nuclear ribosomal DNA markers. Here we report the application of three novel microsatellite VNTR loci to population differentiation in Atlantic salmon. A total of 232 microsatellites, cloned from Atlantic salmon, were classified as perfect, imperfect, and compound repeats. Microsatellite length, as in other teleosts, was significantly larger than published mammalian microsatellites. Primers for PCR amplification of three salmon microsatellites were designed. Allele frequencies, degree of polymorphism, and heterozygosity were estimated for five populations from Nova Scotia, Canada, and from Europe. Nei's genetic distances of 0.02–0.9 were observed among populations. There was a clear discrimination between Canadian and European fish based on unique alleles present at two loci. These Atlantic salmon primers also amplify presumably homologous loci in nine other salmonid species. The polymorphic microsatellites loci reported here demonstrate great potential as genetic markers in population, breeding, and evolutionary studies.
Response of the Laflamme Lake watersheds Quebec, to reduced sulphate deposition (1981–1992)
Authors: Couture Suzanne
Published: July 2008

To verify the effectiveness of Canadian and U.S. programs to reduce SO2 emissions, Environment Canada operates an aquatic ecosystem monitoring program that includes the Laflamme Lake integrated watershed north of Quebec City. Wet atmospheric sulphate deposition to the Laflamme Lake watershed declined between 1981 and 1991, particularly during the latter half of this period. The nitrate concentration increased in precipitation between 1981 and 1991. For the lake water, this resulted principally in a slow reduction in alkalinity between June 1981 and May 1992. After 1986, reductions in lake sulphate concentration were offset principally by reductions in Ca and Mg concentrations. An increase in lake water nitrate concentration was observed after 1986. The gradual loss of lake alkalinity demonstrates that the acid inputs to the lake are still too high for chemical recovery to occur. The potential improvement in lake alkalinity related to reduced sulphate concentration may be lost because of an increasing nitrogen-based acidification.
Reproductive interactions between sympatric brook and brown trout in a small Minnesota stream
Authors: Sorensen Peter W. , Essington Tim , Weigel Dana E. , Cardwell James R.
Published: July 2008

The reproductive activities of sympatric brook (Salvelinus fontinalis) and brown trout (Salmo trutta) in a Minnesota stream were documented on a regular basis for 3 years to determine whether behavioral interactions between these species might influence their spawning activities and success. The spawning seasons of brook and brown trout consistently overlapped by 2–4 weeks, during which time nearly 10% of all sexually active females were simultaneously courted by males of both species. Male brook trout attempted to hybridize most frequently; however, both our behavioral observations and population census suggested that these fish had little success. There was also strong evidence of frequent redd superimposition, particularly by the later spawning and larger brown trout. Analysis of redd site habitat demonstrated that these species had overlapping preferences. Although it seems likely that attempted hybridization and redd superimposition work to the disadvantage of both species, the effects of these activities are likely to be particularly severe for the brook trout, which spawns earlier in the season, is smaller in size, and rarely survives to be old enough to spawn twice. Thus, reproductive interactions may be partially responsible for the displacement of brook trout by brown trout in many regions of North America.
The influence of elevation on benthic community responses to heavy metals in Rocky Mountain streams
Authors: Clements William H. , Kiffney Peter M.
Published: July 2008

We examined the influence of elevation on benthic macroinvertebrate community responses to heavy metals at 33 sites in six Colorado streams where zinc (Zn) concentration ranged from 2 to 691 μg/L and elevation ranged from 2200 to 3500 m above sea level. We assigned the 33 sites to one of four categories, on the basis of the total Zn concentration and the hardness-based criterion for Zn. Number of taxa, abundance, and species richness of mayflies (Ephemeroptera), and abundance of most mayfly and stonefly (Plecoptera) taxa were significantly reduced at sites where Zn concentration exceeded the hardness-based criterion. Although most measures of benthic community structure were not affected at sites where the Zn concentration was less than the criterion, the species richness of mayflies and the abundance of Heptageniidae, Drunella, and Rhyacophila were significantly reduced. Results of stepwise multiple regression analysis and canonical discriminant analysis showed that the effects of Zn on benthic community structure were influenced by elevation. These natural changes in benthic communities confound results of biomonitoring studies and must be considered when assessing heavy metal impacts. Total abundance and species richness of mayflies, and abundance of Heptageniidae were the most reliable indicators of heavy metal impacts in our southern Rocky Mountain streams.
Relative sensitivity of brown and rainbow trout to pulsed exposures of an acutely lethal mixture of metals typical of the Clark Fork River, Montana
Authors: Marr J. C. A. , Bergman H. L. , Parker M. , Lipton J. , Cacela D. , Erickson W. , Phillips G. R.
Published: July 2008

Brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) fry and juveniles were episodically or continuously exposed to a metals mixture (Zn, Cu, Pb, Cd): the concentrations and ratios of the metals, and variations in water quality (pH, hardness), were selected to represent conditions measured during episodic storm events in the Clark Fork River, Montana. Brown trout fry were more sensitive (lower LC50) than rainbow trout fry to the metals in 8-h exposures with constant hardness and pH, but less sensitive to elevated metal concentrations in conjunction with depressed hardness and pH. Fry were more sensitive than juveniles when exposure was continuous, but neither life stage was clearly more sensitive when exposure was pulsed. Whole-body concentrations of K+ and Ca2+ but not Na+ were significantly depressed in fry exposed to metals. Results support the hypotheses that changes in water quality during thunderstorms are lethal to fry and juvenile life stages of brown and rainbow trouts and that the relative sensitivity of the species to the metals mixture may explain their distributions in the Clark Fork River. Low-frequency extreme conditions may effectively act as a bottleneck on the viability of populations whose relative sensitivities to such extremes may control distributions of species in a system.
Differences in relative sensitivity of naive and metals-acclimated brown and rainbow trout exposed to metals representative of the Clark Fork River, Montana
Authors: Marr J. C. A. , Bergman H. L. , Lipton J. , Hogstrand C.
Published: July 2008

Naive and metals-acclimated juvenile brown (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) were exposed to a metals mixture containing zinc, copper, lead, and cadmium, to compare relative sensitivities to metals concentrations typical of the Clark Fork River, Montana. Differences in the survival responses (tolerance versus resistance) measured for naive fish indicated that the rainbow trout are more tolerant (higher 96-h LC50) of the metals mixture, yet the naive rainbow and brown trout showed similarities in resistance (mean time to death). Differences for metals-acclimated fish indicated that brown trout are more resistant. Thus, the relative sensitivity of brown and rainbow trout varies with both the survival response measured and pre-exposure effects of metals on the physiological condition of the animal. Brown trout continued to acquire metals resistance for up to 5 weeks during acclimation to chronic concentrations of the metals mixture. Hepatic metallothionein and copper residue levels were positively correlated in both naive and metals-acclimated trout, and an energetic cost of metals acclimation was evidenced by reduced weight in brown trout acclimated to the metals. In contrast, rainbow trout demonstrated the least degree of acclimation and no significant growth inhibition was observed.
Hierarchical forest management with anticipation: an application to tactical–operational planning integration
Authors: Beaudoin D. , Frayret J.-M. , LeBel L.
Published: July 2008

This paper examines the problem of harvest capacity planning at a tactical level. Annual capacity planning allows planners to determine the number of contractors to hire per period throughout the year and to define the duration of their contracts. In practice, this process usually involves the analysis of historical data regarding the operational use of capacity and aggregated demand forecast, the output of which then serves to plan harvest operations. Although this form of hierarchical planning reduces the complexity of the task, the decomposition into subproblems that must be successively resolved can lead to infeasibility or poor use of harvesting capacity. The specific problem addressed here resides in how one can consider the operational impact of harvesting decisions taken at the tactical level to ensure a plan’s feasibility at the operational level. We present a tactical planning process based on Schneeweiss’ generic hierarchical modeling approach. A computational experiment demonstrates how a tactical planning process is influenced by the input of the operational level anticipation model. The anticipation approach we propose appears to be a valid method to better integrate key operational-level decisions into tactical plans.
Sphagnum mosses limit total carbon consumption during fire in Alaskan black spruce forests
Authors: Shetler Gordon , Turetsky Merritt R. , Kane Evan , Kasischke Eric
Published: July 2008

The high water retention of hummock-forming Sphagnum species minimizes soil moisture fluctuations and might protect forest floor organic matter from burning during wildfire. We hypothesized that Sphagnum cover reduces overall forest floor organic matter consumption during wildfire compared with other ground-layer vegetation. We characterized variability in soil organic layer depth and organic matter stocks in two pairs of burned and unburned black spruce ( Picea mariana (Mill.) BSP) stands in interior Alaska. In the unburned stands, microsites dominated by Sphagnum had more than twice as much soil organic matter·m–2 as microsites dominated by feather moss and (or) lichens. Whereas 20% of soil organic matter was consumed during fire in microsites dominated by Sphagnum, 45% was consumed in microsites dominated by the feather moss and (or) lichens. Across 79 recently burned black spruce stands, unburned moss abundance (primarily remnant Sphagnum hummocks), landscape position (backslope, flat upland, flat lowland classes), and the interaction among these variables explained 60% of postfire organic soil depths. We suggest that “Sphagnum sheep” could serve as a useful visual indicator of variability in postfire soil carbon stocks in boreal black spruce forests. Sphagnum mosses are important ecosystem engineers not only for their influence on decomposition rates, but also for their effect on fuel consumption and fire patterning.
Forest structure estimation and pattern exploration from discrete-return lidar in subalpine forests of the central Rockies
Authors: Sherrill K. R. , Lefsky M. A. , Bradford J. B. , Ryan M. G.
Published: July 2008

This study evaluates the relative ability of simple light detection and ranging (lidar) indices (i.e., mean and maximum heights) and statistically derived canonical correlation analysis (CCA) variables attained from discrete-return lidar to estimate forest structure and forest biomass variables for three temperate subalpine forest sites. Both lidar and CCA explanatory variables performed well with lidar models having slightly higher explained variance and lower root mean square error. Adjusted R2 values were 0.93 and 0.93 for mean height, 0.74 and 0.73 for leaf area index, and 0.93 and 0.85 for all carbon in live biomass for the lidar and CCA explanatory regression models, respectively. The CCA results indicate that the primary source of variability in canopy structure is related to forest height, biomass, and total leaf area, and the second most important source of variability is related to the amount of midstory foliage and tree density. When stand age is graphed as a function of individual plot scores for canonicals one and two, there is a clear relationship with stand age and the development of stand structure. Lidar-derived biomass and related estimates developed in this work will be used to parameterize decision-support tools for analysis of carbon cycle impacts as part of the North American Carbon Program.
Radar observation and aerial capture of mountain pine beetle,Dendroctonus ponderosaeHopk. (Coleoptera: Scolytidae) in flight above the forest canopy
Authors: Jackson Peter L. , Straussfogel Dennis , Lindgren B. Staffan , Mitchell Selina , Murphy Brendan
Published: July 2008

An outbreak of the mountain pine beetle ( Dendroctonus ponderosae Hopk.) in central British Columbia, Canada, has reached an unprecedented size and intensity and has been spreading. The 2005 emergence and subsequent flight of mountain pine beetle was studied using direct observation of emergence, weather radar imagery, and aerial capture. To verify that the daytime, clear-air radar returns seen during this period were indeed generated by airborne mountain pine beetles, aerial sampling in the area covered by the radar was performed using a drogue capture net towed by a single-engine light aircraft. Results verify that airborne mountain pine beetles are being detected by the weather radar and that, during the emergence period, significant numbers of mountain pine beetles can be found at altitudes up to more than 800 m above the forest canopy. An estimate of transport distance indicates that mountain pine beetles in flight above the forest canopy may move 30–110 km·day–1. An estimate of the instantaneous density of mountain pine beetles in flight above the canopy on flight days in 2005 indicate a mean (maximum) density of 4950 (18 600) beetles·ha–1.
Amount of downed woody debris and its prediction using stand characteristics in boreal and mixedwood forests of Ontario, Canada
Authors: Ter-Mikaelian Michael T. , Colombo Stephen J. , Chen Jiaxin
Published: July 2008

We analyzed data on downed woody debris (DWD) from 435 permanent sample plots in boreal and mixedwood forests of Ontario seeking empirical relationships to predict DWD quantity from stand attributes. In each permanent sample plot, data were collected along three transects, including diameter, tree species, and degree of decomposition of DWD pieces with diameter greater than or equal to 7.5 cm at the point of intersection with the transect. Amounts of DWD in sample plots ranged from 0.7 to 402.7 m3·ha–1 and from 0.1 to 103.4 t·ha–1. Mean DWD values were 65.4 m3·ha–1 and 15.9 t·ha–1 in softwood- and 61.9 m3·ha–1 and 16.5 t·ha–1 in hardwood-dominated plots. Our analysis revealed no relationship between DWD and stand age, site index, or stocking for plots dominated by black spruce ( Picea mariana (Mill.) BSP), eastern white pine ( Pinus strobus L.), sugar maple ( Acer saccharum Marsh.), and red oak ( Quercus rubra L.) and weak relationships for plots dominated by jack pine ( Pinus banksiana Lamb.), red pine ( Pinus resinosa Ait.), trembling aspen ( Populus tremuloides Michx.), and white birch ( Betula papyrifera Marsh.). We submit that DWD in Ontario’s forests should be treated as a constant factor until the relationship between the amount of DWD and present stand condition is better understood and discuss considerations for future studies on DWD.
Dietary Manipulation of Histone Structure and Function
Authors: Delage Barbara , Dashwood Roderick H.
Published: July 2008

Post-translational modifications of histones are the subject of intensive investigations with the aim of decoding how they regulate, alone or in combination, chromatin structure, genomic stability, and gene expression. Major epigenetic programming events take place during gametogenesis and fetal development and are thought to have long-lasting consequences on adult health. Epidemiological and experimental studies have pointed toward maternal nutrition as a major player during prenatal development in influencing disease susceptibility later in life. Although the mechanisms underlying such observations are not well elucidated, epigenetic alterations of histones by particular maternal diets might be of central importance. Moreover, as much as dietary sources can influence epigenetic programming during pregnancy, they have started to be implicated in cancer chemoprevention, via the targeting of reversible epigenetic deregulations at the level of the histones.
Nanocrystalline Diamond as a Coating for Joint Implants: Cytotoxicity and Biocompatibility Assessment
Authors: Amaral Margarida , Gomes Pedro S. , Lopes Maria A. , Santos José D. , Silva Rui F. , Fernandes Maria H.
Published: July 2008

Nanocrystalline diamond (NCD) coatings combine a very low surface roughness with the outstanding diamond properties, such as superlative hardness, low self‐friction coefficient, high wear and corrosion resistance, and biotolerance, which are ideal features for applications in medicine (knee and hip replacement) and surgical tools. The present work presents a comprehensive study of the cytotoxicity and biocompatibility of NCD films grown by hot‐filament chemical vapour deposition (HFCVD) technique, aiming such future applications. Cytotoxicity was evaluated in vitro by seeding human gingival fibroblasts on the NCD surface for 14 days, while specific biocompatibility was assessed on samples seeded with human bone marrow‐derived osteoblasts during 21 days. The NCD coatings proved to be noncytotoxic in the preliminary human gingival fibroblast cell cultures, as denoted by a notable sequence of cell attachment, spreading, and proliferation events. In the specific biocompatibility assay envisaging bone tissue applications, NCD coatings induced human osteoblast proliferation and the stimulation of differentiation markers, compared to standard polystyrene tissue culture plates.
Bird Watching: An Introduction to Amateur Satellite Spotting
Authors: Marmor Kathy
Published: July 2008

Space satellites are invisible instruments of globalization that influence governmental policies. This paper examines remote sensing satellites as optical devices capable of redefining human cognition. They represent accessibility and openness through the more agreeable paradigm of transparency. However, transparency, like surveillance, is based on the interconnection between power, knowledge and perceptual experience. Artists use a variety of tactical practices, including amateurism, to tease apart these connections. Amateurism dedicates itself to the politics of knowledge. The author concludes, based on examples of her work and that of others, that the potential for political intervention exists when knowledge is paired with action.
Operating Text and Transcending Machine: Toward an Interdisciplinary Taxonomy of Media Works
Authors: Chow Kenny K.N.
Published: July 2008

This paper uncovers the relationship between texts and machines, two major human inventions seemingly situated at polarities. In the Western tradition, the former originates from Aristotelian poetics and rhetoric, while the latter is associated with science and technology. The two have started to overlap in the 20th century, especially with the advent of the computer—a machine simulating human mental activities. This article begins by revisiting a few cardinal ideas from various scholars. Then, having outlined a corpus of texts in different manifestations related to the essence of machines, the author attempts to devise a preliminary framework for an inventive taxonomy of media artifacts in the post-digital age.
Between Real and Ideal: Documenting Media Art
Authors: Jones Caitlin , Muller Lizzie
Published: July 2008

This paper describes a new approach to documenting media art which seeks to place in dialogue the artist's intentions and the audience's experience. It explicitly highlights the productive tension between the ideal, conceptual existence of the work, and its actual manifestation through different iterations and exhibitions in the real world. The paper describes how the approach was developed collaboratively during the production of a documentary collection for the artwork Giver of Names, by David Rokeby. It outlines the key features of the approach including artist's interview, audience interviews and data structure.
On Multidecadal and Quasi-Decadal North Atlantic Variability
Authors: Álvarez-García F. , Latif M. , Biastoch A.
Published: July 2008

Observed sea surface temperatures (SSTs) in the North Atlantic from 1958 through 2000, as well as data from an ocean model simulation driven with the atmospheric variability observed during the same period, are examined using multichannel singular spectrum analysis. The two leading oscillatory modes are associated with a multidecadal and a quasi-decadal period. The former is connected to a basinwide uniform SST pattern and changes in the deep North Atlantic meridional overturning circulation. The quasi-decadal mode involves a tripolar SST anomaly pattern forced by atmospheric variability with a spatial structure resembling that of the North Atlantic Oscillation (NAO). The upper ocean’s dynamical response to this NAO variability provides an instantaneous positive feedback to the SST pattern, while a delayed negative feedback is due to shallow overturning circulation anomalies.
Parameterized Mesoscale Forcing Mechanisms for Initiating Numerically Simulated Isolated Multicellular Convection
Authors: Loftus Adrian M. , Weber Daniel B. , Doswell Charles A.
Published: July 2008

Two methods designed to parameterize mesoscale ascent in a three-dimensional numerical cloud model via near-surface momentum and heat fluxes are presented and compared to the commonly used technique of an initial perturbation placed within the model initial condition. The flux techniques use a continuously reinforced thermal or convergent low-level wind field to produce upward vertical motion on the order of 10 cm s−1, by which deep, moist convection can be initiated. The sensitivity of the convective response to the type, strength, and size of the forcing is evaluated using numerical simulations of a conditionally unstable environment with weak unidirectional shear. Precipitation-free cloud processes are used to further simplify the model response to the forcing. The three methods tested produce an initial convective response, but only the momentum and heat flux methods are able to produce sustained deep convection that approximately resembles isolated multicellular convection. Cell regeneration periods, defined as the elapsed time between subsequent vertical velocity maxima passing through a constant level in the updraft region above the source, vary from 8 to 25 min, depending on the forcing type, magnitude, and geometry.
Structure and Formation Mechanism on the 24 May 2000 Supercell-Like Storm Developing in a Moist Environment over the Kanto Plain, Japan
Authors: Shimizu Shingo , Uyeda Hiroshi , Moteki Qoosaku , Maesaka Takeshi , Takaya Yoshimasa , Akaeda Kenji , Kato Teruyuki , Yoshizaki Masanori
Published: July 2008

The structure and formation mechanism of a supercell-like storm in a moist environment below a melting layer were investigated using dual-Doppler radar analysis and a cloud-resolving storm simulator (CReSS). The supercell-like storm developed over the Kanto Plain, Japan, on 24 May 2000. The environment of the supercell-like storm possessed large convective available potential energy (1000 J kg−1), strong vertical wind shear (4.2 × 10−3 s−1 between the surface and 5 km above sea level), and a moist layer (the relative humidity was 60%–90% below a melting layer at 3 km in height). The dual-Doppler radar analysis with a variational method revealed that the supercell-like storm had similar structures to those of a typical supercell in a dry environment below a melting layer, such as that in the Great Plains in the United States. The structures included a hook echo, an overhanging echo structure, and a strong updraft with strong vertical vorticity. However, some of the characteristics of the supercell-like storm differed from those of a typical supercell. For example, a weak downdraft, a weak outflow, a weak inflow, and a short time maintenance of a single cyclonically rotating updraft (about 30 min) were noted. Dual-Doppler radar analysis revealed that the convergence between the weak outflow and the weak inflow kept its location just under the updraft for about 30 min; in other words, the strength of the outflow balanced the strength of the inflow. The observed features were simulated well using CReSS, and the thermodynamical features of the formation mechanism were revealed. The weak downdraft with a small evaporative cooling rate was simulated in a moist layer below the melting layer at 3 km in height. The small evaporation cooling was a major cause of the weak downdraft and the weak outflow. Because the outflow was weak and did not cut off the initial updraft, the weak inflow was able to keep supplying warm air to the initial updraft for about 30 min. Therefore, the present supercell-like storm could form as a result of the balance of the strengths of the weak inflow and the weak outflow in a moist environment.
Improving the Ocean Initialization of Coupled Hurricane–Ocean Models Using Feature-Based Data Assimilation
Authors: Yablonsky Richard M. , Ginis Isaac
Published: July 2008

Coupled hurricane–ocean forecast models require proper initialization of the ocean thermal structure. Here, a new feature-based (F-B) ocean initialization procedure in the GFDL/University of Rhode Island (URI) coupled hurricane prediction system is presented to account for spatial and temporal variability of mesoscale oceanic features in the Gulf of Mexico, including the Loop Current (LC), Loop Current eddies [i.e., warm-core rings (WCRs)], and cold-core rings (CCRs). Using only near-real-time satellite altimetry for the “SHA-assimilated” case, the LC, a single WCR, and a single CCR are assimilated into NAVOCEANO’s Global Digitized Environmental Model (GDEM) ocean temperature and salinity climatology along with satellite-derived daily sea surface temperature (SST) data from 15 September 2005 to produce a more realistic three-dimensional temperature field valid on the model initialization date (15 September 2005). For the “fully assimilated” case, both near-real-time altimetry and real-time in situ airborne XBT (AXBT) temperature profiles are assimilated into GDEM along with SST to produce the three-dimensional temperature field. Vertical profiles from the resulting SHA-assimilated and fully assimilated temperature fields are compared to 18 real-time AXBT temperature profiles, the ocean climatology (GDEM), and an alternative data-assimilated product [the daily North and Equatorial Atlantic Ocean Prediction System Best Estimate (RSMAS HYCOM), which uses an Optimal Interpolation (OI) based assimilation technique] to determine the relative accuracy of the F-B initialization procedure presented here. Also, the tropical cyclone heat potential (TCHP) from each of these profiles is calculated by integrating the oceanic heat content from the surface to the depth of the 26°C isotherm. Assuming the AXBT profiles are truth, the TCHP rms error for the F-B SHA-assimilated case, the F-B fully assimilated case, the GDEM ocean climatology, and the RSMAS HYCOM product is 12, 10, 45, and 26 kJ cm−2, respectively.
The Influence of the El Niño–Southern Oscillation on Cloud-to-Ground Lightning Activity along the Gulf Coast. Part II: Monthly Correlations
Authors: Laing Arlene , LaJoie Mark , Reader Steven , Pfeiffer Karl
Published: July 2008

The El Niño–Southern Oscillation (ENSO) cycle is known to influence weather and climate along the Gulf Coast region, causing anomalously high precipitation during El Niño winters. This region is also known for having the highest lightning flash density in the United States. An 8-yr dataset (1995–2002) of cloud-to-ground (CG) lightning flashes was analyzed to determine if the ENSO cycle influences lighting activity along the Gulf Coast region. Simple Pearson’s correlations were computed between concurrent monthly pairings of Niño-3.4 sea surface temperature (SST) and CG lightning flash deviation values from the study area. The correlation results are mapped and analyzed for links to meteorological features.

Statistically significant correlation values greater than 0.8 were noted over large swaths of the study area during each winter month. The highest correlations were arranged in banded swaths and associated with regions of low flash densities during December and February. In January, areas of high correlation were spatially coincident with areas of enhanced flash density. Both the enhanced CG flash regions and high correlation values and patterns are indicative of a southerly shift in the midlatitude storm track known to occur during warm ENSO events. During the spring and summer, most of the region has weak correlation with ENSO except for August, which has a large area of negative correlations. These findings indicate that lightning increases during La Niña summers. Correlation patterns in late fall are similar to those of winter. The ENSO–lightning relationship has implications for hazard assessment and can be a useful tool for long-term seasonal planning.
Idealized Mesoscale Convective System Structure and Propagation Using Convective Parameterization
Authors: Correia James , Arritt Raymond W. , Anderson Christopher J.
Published: July 2008

The development and propagation of mesoscale convective systems (MCSs) was examined within the Weather Research and Forecasting (WRF) model using the Kain–Fritsch (KF) cumulus parameterization scheme and a modified version of this scheme. Mechanisms that led to propagation in the parameterized MCS are evaluated and compared between the versions of the KF scheme. Sensitivity to the convective time step is identified and explored for its role in scheme behavior. The sensitivity of parameterized convection propagation to microphysical feedback and to the shape and magnitude of the convective heating profile is also explored.

Each version of the KF scheme has a favored calling frequency that alters the scheme’s initiation frequency despite using the same convective trigger function. The authors propose that this behavior results in part from interaction with computational damping in WRF. A propagating convective system develops in simulations with both versions, but the typical flow structures are distorted (elevated ascending rear inflow as opposed to a descending rear inflow jet as is typically observed). The shape and magnitude of the heating profile is found to alter the propagation speed appreciably, even more so than the microphysical feedback. Microphysical feedback has a secondary role in producing realistic flow features via the resolvable-scale model microphysics. Deficiencies associated with the schemes are discussed and improvements are proposed.
Surface Analysis of the Rear-Flank Downdraft Outflow in Two Tornadic Supercells
Authors: Hirth Brian D. , Schroeder John L. , Weiss Christopher C.
Published: July 2008

The rear-flank downdraft regions of two tornadic supercells were sampled on 12 June 2004 and 9 June 2005 using four “mobile mesonet” probes. These rear-flank downdraft outflows were sampled employing two different data collection routines; therefore, each case is described from a different perspective. The data samples were examined to identify variations in measured surface equivalent potential temperature, virtual potential temperature, and kinematics. In the 12 June 2004 case, the tornadic circulation was accompanied by small equivalent potential temperature deficits within the rear-flank downdraft outflow early in its life followed by increasing deficits with time. Virtual potential temperature deficits modestly increased through the duration of the sample as well. The 9 June 2005 case was highlighted by heavy precipitation near the tornado itself and relatively small negative, or even positive, equivalent and virtual potential temperature perturbations. Large horizontal variations of surface thermodynamic properties were also noted within several regions of this rear-flank downdraft outflow.
A Funnel Cloud in a Convective Cloud Line to the Rear of a Surface Cold Front
Authors: Bluestein Howard B.
Published: July 2008

This brief case study describes the unusually benign environment in which a funnel cloud formed along a line of convective towers during the summer in Kansas. The parent cloud line was solitary and very narrow, yet organized on the mesoscale. The cloud line appeared to be best correlated with a zone of horizontal temperature gradient to the northwest of cool (evaporatively produced) outflow from an area of precipitation located just to the rear of a cold front. Implications for forecasting such an event are noted.
Ruptured Aneurysm of the Sinus of Valsalva in Association with Persistent Left Superior Vena Cava
Authors: Yildirir Aylin , Batur Mustafa Kemal , Kabakci Giray , Yildirir Aylin
Published: July 2008

A 58-year-old man presenting with chest pain and dyspnea was diagnosed by trans esophageal echocardiography and cardiac catheterization to have the rare combination of ruptured aneurysm of noncoronary sinus of Valsalva into the right ventricle in associ ation with persistent left superior vena cava. These defects were confirmed at cardiac surgery. This case shows the importance of complementary use of invasive and noninva sive methods together in the diagnosis of rare combinations of lesions.
Paravalvular Regurgitation: A Rare Complication Following Valve Replacement Surgery
Authors: Safi Arshad M. , Kwan Tak , Afflu Ernest , Al Kamme Ahmad , Salciccioli Louis
Published: July 2008

Paravalvular regurgitation is an uncommon but important complication, usually following valve replacement surgery. Early recognition and management are important for reop erations are associated with high morbidity and mortality rates. Presently, little data are available on this topic. The authors review the subject.
Intravenous Leiomyomatosis Extending into the Right Ventricular Cavity: One-Stage Radical Operation Using Cardiopulmonary Bypass
Authors: Wakiyama Hidetaka , Sugimoto Takaki , Ataka Keiji , Yamashita Chojiro , Tsuji Yoshihiko , Nakagiri Keitaro , Inoue Kyozo , Okada Masayoshi , Wakiyama Hidetaka
Published: July 2008

The authors describe a 47-year-old woman with intravenous leiomyomatosis (IVL) extending into the right ventricular cavity. This rare entity is a neoplasm originating from smooth muscle of the uterus, with vermiform extensions into the inferior vena cava. The patient underwent a one-stage operation under simultaneous sternotomy and laparo tomy, and radical excision of the tumor was successfully achieved with use of normoth ermic cardiopulmonary bypass. Although this tumor is histologically benign, it sometimes extends into the cardiac cavity and causes sudden death due to incarceration into the atri oventricular orifice. Moreover, recurrence or lung metastasis of IVL has been reported. The authors recommend a one stage-radical resection of the tumor or a two-staged operation within a short interval. In the literature, 24 surgical cases of the intravenous leiomyomatosis with intracardiac extension have been reported. The diagnosis and surgical treatment of this tumor are reviewed and discussed.