A moored array deployed across the shelf break in the northeast South China Sea during April-May 2001 collected sufficient current and pressure data to allow estimation of the barotropic tidal ...currents and energy fluxes at five sites ranging in depth from 350 to 71 m. The tidal currents in this area were mixed, with the diurnal O1 and K1 currents dominant over the upper slope and the semidiurnal M2 current dominant over the shelf. The semidiurnal S2 current also increased onshelf (northward), but was always weaker than O1 and K1. The tidal currents were elliptical at all sites, with clockwise turning with time. The O1 and K1 transports decreased monotonically northward by a factor of 2 onto the shelf, with energy fluxes directed roughly westward over the slope and eastward over the shelf. The M2 and S2 current ellipses turned clockwise and increased in amplitude northward onto the shelf. The M2 and S2 transport ellipses also exhibited clockwise veering but little change in amplitude, suggesting roughly nondivergent flow in the direction of major axis orientation. The M2 energy flux was generally aligned with the transport major axis with little phase lag between high water and maximum transport. These barotropic energy fluxes are compared with the locally generated diurnal internal tide and high-frequency internal solitary-type waves generated by the M2 flow through the Luzon Strait.
Temperature and salinity variability over the crest and southern flank of Georges Bank are investigated using moored observations obtained from February to August 1995 and historical data. There was ...a large seasonal variation in water temperature, which decreased 1°C–2°C in February to a minimum of 5°C due to surface cooling and wind‐forced cross‐bank advection, and then increased steadily due to surface heating, reaching 10°C (southern flank) to 17°C (crest) in August. The crest warmed more than the southern flank because it is shallower. Temperature variability at shorter timescales (days to weeks) was primarily due to surface heating on the crest and horizontal advection on the southern flank. Salinity variability over the southern flank was primarily associated with two processes. Intrusions of warm, salty, shelf‐slope‐front water in May and August were associated with Gulf Stream warm‐core rings, but did not cause longer‐term changes on the southern flank or penetrate onto the crest. Alongbank advection brought low‐salinity, cool Scotian Shelf Water to the southern flank sites in March and early May, about three weeks after crossing the Northeast Channel onto the northeastern flank of Georges Bank (≈130 km away). This low‐salinity water on the southern flank in the spring did not penetrate immediately onto the crest. Instead, the crest salinity steadily decreased from April to August due to both precipitation (evaporation was small) and, based on historical data, a tidally forced, cross‐frontal exchange flow (0.01–0.02 m s−1) that both freshens and cools the crest.
Scotian Shelf crossovers during winter/spring 1999 Smith, Peter C.; Flagg, Charles N.; Limeburner, Richard ...
Journal of Geophysical Research - Oceans,
November 2003, Letnik:
108, Številka:
C11
Journal Article
Recenzirano
A field program detected direct “crossover” of Scotian Shelf Water (SSC) from Browns to Georges Bank during winter/spring 1999 using (1) moored measurements, (2) drogued drifters, and (3) satellite ...imagery. Statistics of the 30‐day trajectories indicate that (18, 55) ± 17% of the drifters crossed the (100, 200) m isobaths on Georges Bank. Transit times ranged from 2 to 26 days. Four of the drifters crossed onto the Northeast Peak (NEP) coinciding with the detection of Scotian Shelf Water at the central NEP mooring. These events are deemed “significant” because they serve to deliver particles from the Scotian Shelf directly to the gadoid spawning grounds on Georges Bank. Depths of the SSC layers lie between 15 and 50 m, and “residence times” for the Scotian Shelf Water on the NEP are estimated at 3 to 4 weeks. Canonical correlation analysis of the NEP temperature and salinity records suggest that 10% of the correlation structure among the variables is related to SSCs, while 70% is associated with the annual cycle. A search for SSC driving mechanisms reveals that (1) interannual variability of the annual freshwater discharge from the Gulf of St. Lawrence is not a factor, (2) Ekman‐like response of near‐surface currents to southeast wind stress plays a role but is not the dominant factor, and (3) mesoscale baroclinic features penetrating Northeast Channel from offshore are the most likely cause. Furthermore, the incidence of SSCs may be related to offshore fronts whose proximity is positively correlated with the North Atlantic Oscillation index.
Vascular function of the peripheral circulation in patients with nephrosis.
Nephrotic syndrome is associated with abnormal lipoprotein metabolism and increased risk of coronary heart disease. ...Endothelial dysfunction, an early phase of atherogenesis that manifests as impaired flow-mediated dilation (FMD) of the peripheral circulation, may link these associations.
We examined endothelial function of the brachial artery and forearm resistance arteries in 15 patients with nephrosis (NP), 15 patients with primary hyperlipidemia (HL) alone, and 15 normolipidemic, nonproteinuric subjects (NC) matched for age, sex, and weight. The NP and HL groups had similar serum cholesterol and triglyceride concentrations. Post-ischemic FMD (endothelium-dependent) and glyceryl trinitrate-mediated dilation (GTNMD; endothelium-independent) of the brachial artery were studied using ultrasonography and computerized edge detection software. Postischemic forearm blood flow was also measured using plethysmography.
Postischemic FMD of the brachial artery was significantly lower in the NP and HL groups compared with NC group (mean ± SE): NP 4.91 ± 0.8%, HL 4.53 ± 0.6%, NC 8.45 ± 0.5% (P < 0.001). There were no significant differences among the groups in baseline diameter and GTNMD of the brachial artery, nor in maximal forearm blood flow and flow debt repayment of the forearm microcirculation. Significant differences in FMD among the groups were principally related to differences in serum low-density lipoprotein cholesterol.
Patients with NP have abnormal endothelium-dependent but preserved endothelium-independent dilation of the brachial artery following an ischemic stimulus. Postischemic forearm microcirculatory function is unimpaired. Dyslipoproteinemia is probably the principal cause of endothelial dysfunction of conduit arteries in patients with NP and the basis for their increased risk of cardiovascular disease.
The benefits of recording the tumor, node, and metastasis (TNM) stages of cancer patients are well accepted, but little is known about how accurately this is performed. An audit was performed to ...determine the accuracy of recorded stage and to act as a baseline before the implementation of an education program.
All new patient referrals to Princess Margaret Hospital between July 1 and August 31, 1997, were reviewed. An audit panel composed of five health record technicians (HRTs) and 10 doctors was assembled. Each auditor reviewed 10% of the health record. If there was a discrepancy between the stage in the health record and the auditor stage, then the final stage was determined by the audit committee. Analysis of the agreement between the health record, the physician auditor, the HRT auditor, and the final stage was performed.
A total of 855 patients were referred with a new diagnosis of a malignancy for which there was a TNM stage system; 833 patients (97.4%) had a stage assigned. There was agreement between the health record stage and final stage in 80% (95% confidence interval CI, 77% to 82%) of cases for clinical stage, compared with 90% (95% CI, 87% to 92%) for pathologic stage. Of the major site groups, lung was the least accurately recorded. The most common major discrepancies were due to the recording of X when a definite category could be assigned.
This audit demonstrates the importance of staging and provides impetus to develop staging guidelines and education programs.
Moored fish cage dynamics in waves and currents Fredriksson, D.W.; Swift, M.R.; Eroshkin, O. ...
IEEE journal of oceanic engineering,
2005-Jan., 2005-01-00, 20050101, Letnik:
30, Številka:
1
Journal Article
Recenzirano
Recent work in the area of open ocean aquaculture system dynamics has focused separately upon either the response of fish cages in waves or the steady drag response due to ocean currents. In reality, ...however, forcing on these open ocean structures is a nonlinear, multidirectional combination of both wave and current profiles. At the University of New Hampshire-operated Open Ocean Aquaculture site, data were collected from a wave measurement buoy and a downward-looking Acoustic Doppler Current Profiler to characterize the surface elevation and water velocity profiles during an extreme northeast storm event. In addition to waves and currents, fish cage motion response in heave, surge, and pitch was inferred from accelerometer measurements during the same storm. The environmental data sets obtained during the peak of the storm were processed, analyzed, and used as input to a dynamic finite-element model. Simulations were performed using three load case scenarios: 1) in both waves and currents; 2) in waves only; and 3) in currents only. Model motion response results in both the time and frequency domain were compared with data obtained in situ . In addition to the motion response tests, the wave and current forcing influencing the mooring line tension response was also investigated. Analysis shows that in this case, the currents do not severely influence the oscillatory motion response, but do cause the cage to tilt, layback, and sink. The wave and current interaction effect did, however, influence the anchor line loads with a portion being attributed to nonlinear effects.
Several experiments to measure postimpact burial of seafloor mines by scour and fill have been conducted near the Woods Hole Oceanographic Institution's Martha's Vineyard Coastal Observatory (MVCO, ...Edgartown, MA). The sedimentary environment at MVCO consists of a series of rippled scour depressions (RSDs), which are large scale bedforms with alternating areas of coarse and fine sand. This allows simultaneous mine burial experiments in both coarse and fine sand under almost identical hydrodynamic forcing conditions. Two preliminary sets of mine scour burial experiments were conducted during winters 2001-2002 in fine sand and 2002-2003 in coarse sand with a single optically instrumented mine in the field of view of a rotary sidescan sonar. From October 2003 to April of 2004, ten instrumented mines were deployed along with several sonar systems to image mine behavior and to characterize bedform and oceanographic processes. In fine sand, the sonar imagery of the mines revealed that large scour pits form around the mines during energetic wave events. Mines fell into their own scour pits, aligned with the dominant wave crests and became level with the ambient seafloor after several energetic wave events. In quiescent periods, after the energetic wave events, the scour pits episodically infilled with mud. After several scour and infilling events, the scour pits were completely filled and a layer of fine sand covered both the mines and the scour pits, leaving no visible evidence of the mines. In the coarse sand, mines were observed to bury until the exposed height above the ripple crests was approximately the same as the large wave orbital ripple height (wavelengths of 50-125 cm and heights of 10-20 cm). A hypothesis for the physical mechanism responsible for this partial burial in the presence of large bedforms is that the mines bury until they present roughly the same hydrodynamic roughness as the orbital-scale bedforms present in coarse sand.
The annual evolution of the geostrophic flow structure in the Gulf of Maine was studied with a combined set of moored pressure time-series measurements and five hydrographic surveys from August 1986 ...through September 1987. A series of quasi-synoptic dynamic height maps depicts a gulf flow structure whose typical spatial scales decrease from order 100 km during the winter to about half that in the summer, when the evolution of surface, intermediate, and deep water masses is most rapid and complex. The unusually large amount of freshwater in the gulf during 1987 was partially responsible for the establishment of a north-south across-gulf front during the summer. Year-long time series of bottom pressure and internal pressure (derived from temperature and conductivity measurements in Georges and Jordan basins) have been differenced with coastal synthetic subsurface pressures (SSP) to yield a history of the basin-scale geostrophic flow variability. A conceptual model of the annual evolution of gull-scale flow, based on a hypothesized interplay of pressure gradient forcing produced by variable inflows (outflows), thermohaline forcing, and, to a lesser extent, wind forcing is presented.
Objective While current emphases on operative teaching focus on “virtual” education, residents and faculty engage most intimately in the operating room. The utilization of intraoperative teaching ...techniques, drawn from adult education principles, is understudied. Design A survey with both quantitative and qualitative elements was administered to surgical residents and their faculty. Thirty-eight analogous questions regarding teaching techniques, populating four general domains, were rated for frequency of application. Respondents were asked to rank best teaching practices and identify other effective educational approaches using open-ended questions. Setting University-based general surgical residency (5 institutions). Participants General surgical residents and their faculty. Results 46 residents (77%) and 37 faculty (63%; mean 17 yrs experience) completed the survey. There was significant disagreement between residents and faculty in how frequently 32 of the 38 teaching techniques were applied (all p < 0.032). Faculty rated the technique “I set and communicate high standards” as the most frequently applied strategy, while residents rated “The faculty demonstrate technical consistency” the highest. The least employed approach, acknowledged by both groups, was “The faculty ask how they might improve their teaching.” There were few differences between perceptions and preferences of junior vs. senior learners, and junior vs. senior faculty. Resident and faculty appreciation of most-effective teaching approaches was similar. Qualitative analysis of the open-ended questions yielded themes which resonate with both learners and teachers: communication processes, time pressures, optimization of the work/teaching environment, teacher engagement, patience/tolerance, autonomy, feedback, learner preparedness, and patient advocacy. Conclusions The perceptions of residents and faculty regarding the frequency of using effective approaches for operative teaching are disparate. While faculty appear to value adult learning principles and perceive that they are employed regularly, residents have a discrepant viewpoint. However, themes that were identified by both residents and faculty through qualitative analysis provide the foundation for educational process improvements.
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