Fate of organochlorine contaminants in arctic and subarctic lakes estimated by mass balance modelling.

Elevated concentrations of some persistent organic pollutants (POPs) in fish from arctic and subarctic lakes have been hypothesized to be due to processes within food webs and fish physiology. We investigated limnological processes and contaminant chemistry as explanations of these elevated concentrations by developing and applying fugacity-based mass balance models to a relatively small lake in the high arctic and a series of larger lakes in the southern Yukon River basin. The results indicate that high arctic lakes are transient and inefficient sinks for POPs.

Modern and historical fluxes of halogenated organic contaminants to a lake in the Canadian arctic, as determined from annually laminated sediment cores.

Two annually laminated cores collected from Lake DV09 on Devon Island in May 1999 were dated using 210Pb and 137Cs, and analyzed for a variety of halogenated organic contaminants (HOCs), including polychlorinated biphenyls (PCBs), organochlorine pesticides, short-chain polychlorinated n-alkanes (sPCAs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs). Dry weight HOC concentrations in Lake DV09 sediments were generally similar to other remote Arctic lakes. Maximum HOC fluxes often agreed well with production maxima, although many compound groups exhibited maxima at or near the sediment surface, much later than peak production.

Gas-particle partitioning of polychlorinated naphthalenes and non- and mono-ortho-substituted polychlorinated biphenyls in arctic air.

Gas-particle partitioning relationships were developed for partitioning of polychlorinated naphthalenes (PCNs) and non- and mono-ortho PCBs in arctic air by regressing observed gas-particle partition coefficients, K(P), at Alert and Dunai in the high Arctic with temperature-adjusted experimental vapor pressures (p(L) degrees ) and octanol-air partition coefficients (K(OA)). Slopes were near -0.5 and 0.

Temporal and spatial variabilities of atmospheric polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and polycyclic aromatic hydrocarbons (PAHs) in the Canadian Arctic: results from a decade of monitoring.

The Northern Contaminants Program (NCP) baseline monitoring project was established in 1992 to monitor for persistent organic pollutants (POPs) in Arctic air. Under this project, weekly samples of air were collected at four Canadian and two Russian arctic sites, namely Alert, Nunavut; Tagish, Yukon; Little Fox Lake, Yukon; Kinngait, Nunavut; Dunai Island, Russia and Amderma, Russia. Selected POPs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides, were analyzed in both the gas and particulate phases.

Visualization of tensor fields using superquadric glyphs.

The spatially varying tensor fields that arise in magnetic resonance imaging are difficult to visualize due to the multivariate nature of the data. To improve the understanding of myocardial structure and function a family of objects called glyphs, derived from superquadric parametric functions, are used to create informative and intuitive visualizations of the tensor fields. The superquadric glyphs are used to visualize both diffusion and strain tensors obtained in canine myocardium.

Fluorinated organic compounds in an eastern Arctic marine food web.

An eastern Arctic marine food web was analyzed for perfluorooctanesulfonate (PFOS, C8F17SO3-), perfluorooctanoate (PFOA, C7F15COO-), perfluorooctane sulfonamide (PFOSA, C8F17SO2NH2), and N-ethylperfluorooctane sulfonamide (N-EtPFOSA, C8F17SO2NHCH2CH3) to examine the extent of bioaccumulation. PFOS was detected in all species analyzed, and mean concentrations ranged from 0.28 +/- 0.

Seasonal and spatial variation of polychlorinated naphthalenes and non-/mono-ortho-substituted polychlorinated biphenyls in arctic air.

Archived extracts of weekly air samples collected at remote arctic monitoring stations at Alert and Tagish, Canada, and Dunai Island, Russia, in 1994-1995 were combined into 4-week composites and analyzed for levels and seasonal trends of polychlorinated naphthalenes (PCNs) and non- and mono-ortho-substituted polychlorinated biphenyls (PCBs). Mean annual sigmaPCN concentrations were 0.69, 0.

Electrical injuries: a 20-year review.

Electrical injuries continue to present problems with devastating complications and long-term socioeconomic impact. The purpose of this study is to review one institution's experience with electrical injuries. From 1982 to 2002, there were 700 electric injury admissions.

Computational cardiac anatomy using MRI.

Ventricular geometry and fiber orientation may undergo global or local remodeling in cardiac disease. However, there are as yet no mathematical and computational methods for quantifying variation of geometry and fiber orientation or the nature of their remodeling in disease. Toward this goal, a landmark and image intensity-based large deformation diffeomorphic metric mapping (LDDMM) method to transform heart geometry into common coordinates for quantification of shape and form was developed.

The force of symmetry revisited: symmetry-to-noise ratios regulate (a)symmetry effects.

Freyd and Tversky's [Am. J. Psychol.

Semivolatile organic compounds in window films from lower Manhattan after the September 11th World Trade Center attacks.

The September 11th World Trade Center (WTC) terrorist attacks resulted in the large-scale release of contaminants that were deposited on the environment of New York City (NYC). Six weeks after the attacks, samples of an organic film on window surfaces were collected and analyzed for polybrominated diphenyl ethers (PBDE), polychlorinated biphenyls (PCB), polychlorinated naphthalenes (PCN), polycyclic aromatic hydrocarbons (PAH), and organochlorine pesticides (OCPs). Concentrations dropped by an order of magnitude within 1 km of the WTC and reached background concentrations by 3.

Transparallel processing by hyperstrings.

Human vision research aims at understanding the brain processes that enable us to see the world as a structured whole consisting of separate objects. To explain how humans organize a visual pattern, structural information theory starts from the idea that our visual system prefers the organization with the simplest descriptive code, that is, the code that captures a maximum of visual regularity. Empirically, structural information theory gained support from psychological data on a wide variety of perceptual phenomena, but theoretically, the computation of guaranteed simplest codes remained a troubling problem.

Localization and function of the Na+/Ca2+-exchanger in normal and detubulated rat cardiomyocytes.

It is controversial whether the Na+/Ca2+-exchanger (NCX) can induce cardiomyocyte contraction through reverse-mode exchange and Ca2+-induced Ca2+ release (CICR). Information about the spatial distribution and functional activity within different sarcolemmal (SL) regions could shed light on this potential role. We raised a new antibody to the NCX and showed by confocal laser scanning microscopy (CLSM) that immunoreactivity is strongly expressed throughout the surface SL and intercalated disk regions with punctate labeling of the vertical transverse (T)-tubules but not the longitudinal T-tubules.

Spatial distribution of polychlorinated naphthalenes in air over the Great Lakes and air-water gas exchange in Lake Ontario.

High-volume air samples were collected during research cruises of Lake Superior in August 1996 and May 1997 and of Lake Ontario (North America) in July and September 1998 and June 2000 and analyzed for polychlorinated naphthalenes (PCNs). Levels of tetra- to octachloronaphthalene (sigmaPCN) varied spatially, with mean values (+/-SD) of 1.78 +/- 0.

Chiral pesticides in soil and water and exchange with the atmosphere.

The enantiomers of chiral pesticides are often metabolised at different rates in soil and water, leading to nonracemic residues. This paper reviews enantioselective metabolism of organochlorine pesticides (OCPs) in soil and water, and the use of enantiomers to follow transport and fate processes. Residues of chiral OCPs and their metabolites are frequently nonracemic in soil, although exceptions occur in which the OCPs are racemic.

Novel technique for cardiac electromechanical mapping with magnetic resonance imaging tagging and an epicardial electrode sock.

Near-simultaneous measurements of electrical and mechanical activation over the entire ventricular surface are now possible using magnetic resonance imaging tagging and a multielectrode epicardial sock. This new electromechanical mapping technique is demonstrated in the ventricularly paced canine heart. A 128-electrode epicardial sock and pacing electrodes were placed on the hearts of four anesthetized dogs.

Intraoperative surgical complication during cesarean section: an observational study of the incidence and risk factors.

Background: The study was intended to estimate the incidence of intraoperative surgical complications with the impact of the educational level of the surgeon and a history of previous cesarean section on intraoperative complications at cesarean childbirth.

Methods: In the period between August 1st 1995 and July 30th 1996, 7782 women gave birth at the three Obstetric Departments in Copenhagen County, Denmark, of which 929 (11.9%) were delivered by cesarean section.

Current combustion-related sources contribute to polychlorinated naphthalene and dioxin-like polychlorinated biphenyl levels and profiles in air in Toronto, Canada.

Polychlorinated naphthalenes (PCNs) and mono- and non-ortho substituted PCBs were analyzed in air from two sites in Toronto, Ontario, Canada to determine whether current combustion-related sources contribute to the levels and profiles of PCNs found in urban air. High-volume air samples were collected periodically at the University of Toronto (UT, a downtown site) and in north Toronto at the Meteorological Service of Canada (MSC). SigmaPCN concentrations ranged from 31 to 78 pg m(-3) at UT and from 7 to 84 pg m(-3) at MSC with concentrations lower at MSC than UT for paired samples.

Blobs strengthen repetition but weaken symmetry.

The human visual system is more sensitive to symmetry than to repetition. According to the so-called holographic approach [J. Math.

Evaluation of registration methods used in frameless stereotactic surgery for the lumbar and cervical regions of the spine.

Computer-assisted pedicle screw insertion is feasible but has proved to be problematic. The purpose of this study was to detail the accuracy of registration techniques and pedicle screw insertion using a frameless stereotactic system. Two registration techniques were evaluated on a model spine.

Imaging-based integrative models of the heart: closing the loop between experiment and simulation.

We describe methodologies for: (a) mapping ventricular activation using high-density epicardial electrode arrays; (b) measuring and modelling ventricular geometry and fibre orientation at high spatial resolution using diffusion tensor magnetic resonance imaging (DTMRI); and (c) simulating electrical conduction; using comprehensive data sets collected from individual canine hearts. We demonstrate that computational models based on these experimental data sets yield reasonably accurate reproduction of measured epicardial activation patterns. We believe this ability to electrically map and model individual hearts will lead to enhanced understanding of the relationship between anatomical structure, and electrical conduction in the cardiac ventricles.

Electromechanical mapping with MRI tagging and epicardial sock electrodes.

Methods currently exist for the precise measurement of local three-dimensional myocardial motion noninvasivly with magnetic resonace imaging tagging. From these motion estimates, strain images representing the local deformation of the myocardium can be formed to show local myocardial contraction. These images clearly show the sequence of mechanical events during the activation and relaxation of the heart, making them ideal to visualize abnormalities caused by asynchronous electrical activation or ischemia.

Polychlorinated naphthalenes and coplanar polychlorinated biphenyls in beluga whale (Delphinapterus leucas) and ringed seal (Phoca hispida) from the eastern Canadian Arctic.

Blubber collected from beluga whales and ringed seals during subsistence hunts in the southern Baffin Island region of the Canadian Arctic were analysed for polychlorinated naphthalenes and eight planar PCB congeners (mono-ortho PCBs: 105, 114, 118 and 156; non-ortho PCBs: 77, 81, 126, 169). SigmaPCN (3-7 Cl) concentrations in blubber ranged from 35.9-383 pg/g (lipid weight; lw) in beluga and 35.

Predictors of quality of life as measured by the Burn Specific Health Scale in persons with major burn injury.

To determine 1) change over time in Quality of Life (QOL) and 2) functional, community reentry, and psychosocial predictors of QOL, data were prospectively collected from adults with major burn injury 2 months after hospital discharge (n = 110) and 6 (n = 97) and 12 (n = 69) months after injury. The dependent QOL variable was the Burn Specific Health Scale (BSHS) and the predictor variables were Brief Symptom Inventory, Functional Assessment Screening Questionnaire, Functional Independence Measure, Pain Analog Scale, and Community Integration Questionnaire. BSHS global scores were unchanged across the measurement periods.