bluuebunny/crossref_metadata_2025 huggingface dataset:
Monocyte Count Is a Predictor of Novel Plaque Formation
Authors: Johnsen Stein Harald , Fosse Einar , Joakimsen Oddmund , Mathiesen Ellisiv B. , Stensland-Bugge Eva , Njølstad Inger , Arnesen Egil
Published: March 2005

Background and Purpose—

Activation of monocytes and differentiation into lipid-laden macrophages are fundamental events in generation of atherosclerotic lesions. There exist few data on monocyte activity and the risk for atherosclerosis. In this prospective population-based study, we examined whether monocyte count in blood is a predictor of future plaque formation in persons without pre-existing carotid atherosclerosis.

Methods—

At baseline, we measured monocyte count, white cell count (WCC), fibrinogen, intima-media thickness (IMT), and traditional cardiovascular risk factors in 2610 men and women aged 25 to 82 years who on ultrasound had no plaque in their right carotid artery. After 7 years of follow-up, a new ultrasound screening was performed and the number of novel plaques was grouped as none, 1 plaque, and 2 or more plaques.

Results—

In multivariate analysis, monocyte count, age, sex, total cholesterol, current smoking, systolic blood pressure, and IMT were independent predictors of novel plaque formation. No significant association was found between plaque formation and either WCC or fibrinogen. For 1 standard deviation (0.17×10
9
) increase in monocyte count, the risk of being in a higher plaque category increased by 18% (OR, 1.18; 95% CI, 1.08 to 1.29). In the highest monocyte quartile, the risk for having plaque compared with the lowest quartile was 1.85 (OR) (95% confidence interval, 1.41 to 2.43). Repeating the analysis without IMT did not change the monocyte estimate. Excluding subjects with cardiovascular disease and diabetes mellitus from analysis neither changed the monocyte estimate.

Conclusion—

Monocyte count is an independent predictor of future plaque formation in subjects without pre-existing carotid atherosclerosis.
Markedly Reduced Apparent Blood Volume on Bolus Contrast Magnetic Resonance Imaging as a Predictor of Hemorrhage After Thrombolytic Therapy for Acute Ischemic Stroke
Authors: Alsop David C. , Makovetskaya Elena , Kumar Sandeep , Selim Magdy , Schlaug Gottfried
Published: March 2005

Background and Purpose—

Accurate assessment of the risk of hemorrhage could help to improve patient selection for thrombolytic therapy and reduce hemorrhagic complications, especially for patients with longer or uncertain time after symptom onset. This study sought to define characteristics of hemodynamic magnetic resonance imaging (MRI), which best predict hemorrhage.

Methods—

Bolus contrast and diffusion MRI were performed before intravenous tissue plasminogen activator (tPA) therapy in 20 patients presenting with acute stroke symptoms within the first 6 hours after symptom onset. Hemorrhage was assessed on follow-up MRI (n=15) and computed tomography (n=5) scans.

Results—

Of the 20 patients studied, 5 had detectable hemorrhage on follow-up scans. Blood volume maps demonstrated virtually no signal within much of the hemorrhagic region, indicating contrast did not arrive by the end of the imaging series (80 seconds). Within the hemodynamically abnormal region, a threshold of at least 126 voxels with blood volume <5% of contralateral normal gray matter separated hemorrhagic patients from nonhemorrhagic with a sensitivity of 100% and a specificity of 73% (
P
<0.01). All subjects with hemorrhage were at least partially reperfused after thrombolysis, whereas most false-positives did not reperfuse (
P
<0.05). The number of low blood volume voxels within individual patients correlated with the number of voxels with apparent diffusion coefficient values <550×10
−6
mm
2
/s (
P
<0.019), another previously proposed predictor of hemorrhage.

Conclusions—

Extremely low or completely absent contrast arrival may indicate tissue-at-risk for hemorrhage before tPA treatment and thus may aid in risk–benefit assessments. Occurrence of hemorrhage within at-risk areas may depend on tissue reperfusion.
Relations of Serum High-Sensitivity C-Reactive Protein and Interleukin-6 Levels With Silent Brain Infarction
Authors: Hoshi Taku , Kitagawa Kazuo , Yamagami Hiroshi , Furukado Shigetaka , Hougaku Hidetaka , Hori Masatsugu
Published: March 2005

Background and Purpose—

Small silent brain infarction (SBI) is often found on magnetic resonance (MR) images of apparently healthy individuals at cardiovascular risk. Particularly, small SBI found in subcortical white matter, basal ganglia, or thalamus is thought to be caused by cerebral small vessel disease. Although several lines of evidence suggest a role of inflammatory processes in atherothrombotic vascular events, their involvement in SBI remains to be determined. This study examines the associations between serum inflammatory markers and SBI as a manifestation of cerebral small vessel disease.

Methods—

One hundred ninety-four patients without histories of cardiovascular accidents were prospectively enrolled for this study. All patients underwent brain MR imaging and carotid ultrasonography, and patients with SBI diagnosed underwent further MR angiography. As common inflammatory markers, serum levels of high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6) were evaluated.

Results—

SBIs were found in 40 patients, and all of those were located in subcortical and infratentorial area, without MR angiographic evidence for obstructive lesions in proximal cerebral arteries. Mean hsCRP and IL-6 levels were higher in patients with SBI than in those without. Also, higher levels of both hsCRP (odds ratio [OR], 1.85 per standard deviation [SD] increase) and IL-6 (OR, 2.00/SD increase) were associated with higher likelihood for SBI. Moreover, the associations were only slightly attenuated when adjusting traditional cardiovascular risk factors and carotid IMT.

Conclusions—

Higher levels of hsCRP and IL-6 appear to be associated with small SBI, suggesting a role of inflammatory processes in cerebral small vessel disease.
Functional Recovery in Aged and Young Rats After Embolic Stroke
Authors: Zhang Li , Zhang Rui Lan , Wang Ying , Zhang Chunling , Zhang Zheng Gang , Meng He , Chopp Michael
Published: March 2005

Background and Purpose—

Advanced age is associated with a decrease in brain plasticity compared with the young adult. Sildenafil, a phosphodiesterase type 5 (PDE5) inhibitor promotes brain plasticity and improves functional outcome after stroke in the young animal. Here, we test the hypothesis that sildenafil provides restorative therapeutic benefit to the aged animal.

Methods—

Male Wistar rats (aged, 18-month old; young, 3-month old) were subjected to embolic stroke. Saline or sildenafil was administered daily at a dose of 2 mg/kg orally or 10 mg/kg subcutaneously for 7 consecutive days starting 24 hour after stroke onset.

Results—

Aged rats exhibited significant impairment of functional recovery and reductions of vascular density, and endothelial cell proliferation compared with young rats. Aged rats treated with sildenafil at a dose of 10 mg/kg but not 2 mg/kg, showed significant improvements of functional recovery and concomitant increases in cortical cyclic guanosine 3′,5′-cyclic monophosphate (cGMP) level, vascular density, endothelial cell proliferation, and synaptogenesis compared with aged rats treated with saline. In young rats, treatment with sildenafil at a dose of 2 or 10 mg/kg significantly enhanced functional recovery and amplified brain plasticity compared with young rats treated with saline.

Conclusion—

Age is associated with reduction of angiogenesis, and poor neurological functional recovery after stroke. However, treatment of aged stroke rats with sildenafil improves functional recovery that is likely fostered by enhancement of angiogenesis and synaptogenesis.
Blood Pressure Control and Risk of Stroke
Authors: Li Cairu , Engström Gunnar , Hedblad Bo , Berglund Göran , Janzon Lars
Published: March 2005

Background and Purpose—

Adequate control of blood pressure (BP) is a cornerstone in stroke prevention. This study explored the risk of stroke in relation to the quality of BP control in a population-based cohort and whether control of hypertension was related to background characteristics of patients.

Methods—

A total of 27 936 subjects (10 953 men and 16 983 women), 45 to 73 years old, living in Malmö, Sweden participated in the study. Incidence of stroke was followed-up for a mean period of 6 years. Controlled BP was defined as BP <140/90 mm Hg in subjects with pharmacological treatment for hypertension.

Results—

In the whole cohort, 16 648 subjects (60%) had hypertension (BP ≥140/90 mm Hg) and 23% of them received treatment. Among treated hypertensives, 88.2% had BP levels ≥140/90 mm Hg and 49.5% had BP levels ≥160/100 mm Hg. During the follow-up, 137 strokes occurred among treated hypertensive subjects. The crude incidence of stroke was 289/100 000 person-year in controlled hypertensive subjects and 705/100 000 person-year in treated hypertensive subjects with BP ≥140/90 mm Hg. It was estimated that ≈45% of all strokes among subjects with treatment for hypertension might be attributed to uncontrolled BP. In treated hypertensives, the risk of stroke increased significantly with advancing age, current smoking, high level of diastolic BP, and diabetes. In hypertensive subjects without treatment (n=12 819), incidence of stroke was 363/100 000 person-year.

Conclusion—

Uncontrolled BP is highly prevalent in patients with pharmacological treatment for hypertension. More than 90% of stroke in this group occurred in those with uncontrolled BP. Adequate hypertension control may prevent a substantial proportion of first-ever stroke among treated hypertensives.
Pseudovertical Temperature Profiles and the Urban Heat Island Measured by a Temperature Datalogger Network in Phoenix, Arizona
Authors: Fast Jerome D. , Torcolini Joel C. , Redman Randy
Published: March 2005

As part of an air-quality field campaign conducted in Phoenix, Arizona, during the summer of 2001, a network of temperature dataloggers and surface meteorological stations was deployed across the metropolitan area for a 61-day period. The majority of the dataloggers were deployed along two intersecting lines across the city to quantify characteristics of the urban heat island (UHI). To obtain pseudovertical temperature profiles, some of the instrumentation was also deployed along a mountain slope that rose to 480 m above the valley floor. The instrumentation along the mountain slope provided a reasonable approximation of the vertical temperature profile of the free atmosphere over the valley center during the night and a few hours after sunrise. Mean differences of 0.63 and 0.92 K and standard deviations of 1.33 and 1.45 K were obtained when compared with the in situ radiosonde and remote radio acoustic sounding system measurements, respectively. The vertical temperature gradients associated with temperature inversions within 200 m of the surface during the morning were also close to those obtained from the radiosondes. The average UHI during the measurement period was between 2.5° and 3.5°C; however, there was significant day-to-day variability, and it was as large as 10°C during one evening. The peak UHI usually occurred around midnight; however, a strong UHI was frequently observed 2–3 h after sunrise that coincided with the persistence of strong temperature inversions obtained from the radiosonde and the pseudovertical temperature profiles. The nocturnal horizontal temperature gradient was somewhat different than that reported for other large cities, and the UHI did not decrease with increasing wind speeds until the wind speeds exceeded 7 m s−1.
Evening Transition Observations in Phoenix, Arizona
Authors: Brazel A. J. , Fernando H. J. S. , Hunt J. C. R. , Selover N. , Hedquist B. C. , Pardyjak E.
Published: March 2005

Past research has suggested that the evening transition in complex topography typically has several main features, such as (a) continued weak upslope flows persisting 3–5 h after sunset (if the sidewalls of the valley prevent Coriolis-induced turning of winds), thus signifying delayed transition; (b) unsteady local stagnation and vertical mixing within tens of meters above the surface; and (c) transition of stagnation fronts to downslope/downvalley gravity currents during the evening hours, especially at higher-elevation (steeper) slopes, and their arrival at adjoining low-elevation gentle slopes as “slope breezes.” This transition process typically occurs in locales such as Phoenix, Arizona, which has expansive exposure to plains in one direction (to the west and south) and is adjacent to abrupt change in the terrain in other directions (primarily to the north and east). An analysis of wind records from several automated weather stations and a radar wind profiler for selected characteristic periods representing all four seasons and data from a previous major field campaign in the greater Phoenix valley illustrate (i) the shallow nature of transition flows that develop on a year-round basis during frequent clear, calm nights in the desert Southwest and their seasonal sensitivity; (ii) a spatial variation of transition times relative to the only first-order National Weather Service station in the region (Sky Harbor International Airport); (iii) the dependence of transition time (and hence the delay of transition) on the exposure, the elevation, and the magnitude of slope; and (iv) a possible heat-island influence. These observations are quantified using theoretical estimates, and the results are placed in the context of multiscale flows in urban basins.
NWCSAF AVHRR Cloud Detection and Analysis Using Dynamic Thresholds and Radiative Transfer Modeling. Part II: Tuning and Validation
Authors: Dybbroe Adam , Karlsson Karl-Göran , Thoss Anke
Published: March 2005

Algorithms for cloud detection (cloud mask) and classification (cloud type) at high and midlatitudes using data from the Advanced Very High Resolution Radiometer (AVHRR) on board the current NOAA satellites and future polar Meteorological and Operational Weather Satellites (METOP) of the European Organisation for the Exploitation of Meteorological Satellites have been extensively validated over northern Europe and the adjacent seas. The algorithms have been described in detail in Part I and are based on a multispectral grouped threshold approach, making use of cloud-free radiative transfer model simulations. The thresholds applied in the algorithms have been validated and tuned using a database interactively built up over more than 1 yr of data from NOAA-12, -14, and -15 by experienced nephanalysts. The database contains almost 4000 rectangular (in the image data)-sized targets (typically with sides around 10 pixels), with satellite data collocated in time and space with atmospheric data from a short-range NWP forecast model, land cover characterization, elevation data, and a label identifying the given cloud or surface type as interpreted by the nephanalyst. For independent and objective validation, a large dataset of nearly 3 yr of collocated surface synoptic observation (Synop) reports, AVHRR data, and NWP model output over northern and central Europe have been collected. Furthermore, weather radar data were used to check the consistency of the cloud type. The cloud mask performs best over daytime sea and worst at twilight and night over land. As compared with Synop, the cloud cover is overestimated during night (except for completely overcast situations) and is underestimated at twilight. The algorithms have been compared with the more empirically based Swedish Meteorological and Hydrological Institute (SMHI) Cloud Analysis Model Using Digital AVHRR Data (SCANDIA), operationally run at SMHI since 1989, and results show that performance has improved significantly.
An Empirical Model for Predicting the Decay of Tropical Cyclone Wind Speed after Landfall over the Indian Region
Authors: Bhowmik S. K. Roy , Kotal S. D. , Kalsi S. R.
Published: March 2005

An empirical model for predicting the maximum surface wind speed associated with a tropical cyclone after crossing the east coast of India is described. The model parameters are determined from the database of 19 recent cyclones. The model is based upon the assumption that tropical cyclone winds decay exponentially after landfall. A method for correcting the forecast during subsequent observation hours is also presented. Results show that without the correction factor the absolute mean error ranges from 6.1 to 4.9 kt (1 kt = 0.5144 m s−1) and the root-mean-square error ranges from 7.9 to 5.6 kt, with both decreasing over time. With the incorporation of the correction procedure, a significant improvement in the forecast skill is noticed for the case in which it is tested using the dependent sample. The model is expected to be very useful to operational forecasters.
Characteristics of Low-Level Jets over Northern Taiwan in Mei-Yu Season and Their Relationship to Heavy Rain Events
Authors: Chen George Tai-Jen , Wang Chung-Chieh , Lin David Ta-Wei
Published: March 2005

The present study investigates the characteristics of low-level jets (LLJs) (≥12.5 m s−1) below 600 hPa over northern Taiwan in the mei-yu season and their relationship to heavy rainfall events (≥50 mm in 24 h) through the use of 12-h sounding data, weather maps at 850 and 700 hPa, and hourly rainfall data at six surface stations during the period of May–June 1985–94. All LLJs are classified based on their height, appearance (single jet or double jet), and movement (migratory and nonmigratory). The frequency, vertical structure, and spatial and temporal distribution of LLJs relative to the onset of heavy precipitation are discussed.

Results on the general characteristics of LLJs suggest that they occurred about 15% of the time in northern Taiwan, with a top speed below 40 m s−1. The level of maximum wind appeared mostly between 850 and 700 hPa, with highest frequency at 825–850 hPa. A single jet was observed more often (76%) than a double jet (24%), while in the latter case a barrier jet usually existed at 900–925 hPa as the lower branch.

Migratory and nonmigratory LLJs each constituted about half of all cases, and there existed no apparent relationship between their appearance and movement. Migratory LLJs tended to be larger in size, stronger over a thicker layer, more persistent, and were much more closely linked to heavy rainfall than nonmigratory jets. They often formed over southern China between 20° and 30°N and moved toward Taiwan presumably along with the mei-yu frontal system.

Before and near the onset of the more severe heavy rain events (≥100 mm in 24 h) in northern Taiwan, there was a 94% chance that an LLJ would be present over an adjacent region at 850 hPa, and 88% at 700 hPa, in agreement with earlier studies. Occurrence frequencies of LLJs for less severe events (50–100 mm in 24 h) were considerably lower, and the difference in accumulative rainfall amount was seemingly also affected by the morphology of the LLJs, including their strength, depth, elevation of maximum wind, persistence, proximity to northern Taiwan, source region of moisture, and their relative timing of arrival before rainfall. During the data period, about 40% of all migratory LLJs at 850 or 700 hPa passing over northern Taiwan were associated with heavy rainfall within the next 24 h. The figure, however, was much lower compared to earlier studies, and some possible reasons are offered to account for this deficit.
Spectral (Bin) Microphysics Coupled with a Mesoscale Model (MM5). Part II: Simulation of a CaPE Rain Event with a Squall Line
Authors: Lynn Barry H. , Khain Alexander P. , Dudhia Jimy , Rosenfeld Daniel , Pokrovsky Andrei , Seifert Axel
Published: March 2005

Spectral (bin) microphysics (SBM) has been implemented into the three-dimensional fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5). The new model was used to simulate a squall line that developed over Florida on 27 July 1991. It is shown that SBM reproduces precipitation rate, rain amounts, and location, radar reflectivity, and cloud structure much better than bulk parameterizations currently implemented in MM5.

Sensitivity tests show the importance of (i) raindrop breakup, (ii) in-cloud turbulence, (iii) different aerosol concentrations, and (iv) inclusion of scavenging of aerosols. Breakup decreases average and maximum rainfall. In-cloud turbulence enhances particle drop collision rates and increases rain rates. A “continental” aerosol concentration produces a much larger maximum rainfall rate versus that obtained with “maritime” aerosol concentration. At the same time accumulated rain is larger with maritime aerosol concentration. The scavenging of aerosols by nucleating water droplets strongly affected the concentration of aerosols in the atmosphere.

The spectral (bin) microphysics mesoscale model can potentially be used for studies of specific phenomena such as severe storms, winter storms, tropical cyclones, etc. The more realistic reproduction of cloud structure than that obtained with bulk parameterization implies that the model will be more useful for remote sensing applications and in the development of advanced rain retrieval algorithms. The model can also simulate the effect of cloud seeding on rain production.
The Diurnal Cycle of Land–Atmosphere Interactions across Oklahoma’s Winter Wheat Belt
Authors: Haugland Matthew J. , Crawford Kenneth C.
Published: March 2005

This manuscript documents the impact of Oklahoma’s winter wheat belt (WWB) on the near-surface atmosphere by comparing the diurnal cycle of meteorological conditions within the WWB relative to conditions in adjacent counties before and after the wheat harvest.

To isolate the impact of the winter wheat belt on the atmosphere, data from several meteorological parameters were averaged to create a diurnal cycle before and after the wheat harvest. Observations from 17 Oklahoma Mesonet sites within the WWB (during a period of 9 yr) were compared with observations from 22 Mesonet sites in adjacent counties outside the winter wheat belt.

The average diurnal cycles of dewpoint, temperature, and surface pressure exhibited patterns that revealed a distinct mesoscale impact of the wheat fields. The diurnal patterns were consistent with the status of the wheat crop and the grassland in adjacent counties. The impact of the WWB was shown to be more significant during a month when soil moisture was abundant, and minimal during a month when soil moisture was limited. Statistically significant, hydrostatically consistent afternoon surface pressure anomalies suggest that there is a strong possibility of weak mesoscale circulations induced by the WWB.
Characteristics of Monsoon Rainfall around the Himalayas Revealed by TRMM Precipitation Radar
Authors: Bhatt B. C. , Nakamura K.
Published: March 2005

The climatological features of the diurnal cycle and its spatial and temporal variability are investigated around the Himalayas using hourly, 0.05° × 0.05° grid, near-surface rainfall data from the Precipitation Radar (PR) aboard the Tropical Rainfall Measuring Mission (TRMM) satellite during June–July–August (JJA) of 1998–2002. Though sampling errors inherent to TRMM PR measurements around the Himalayas could influence results, PR-observed precipitation features show agreement with previous studies in this region.

The analysis of precipitation characteristics presented here is based on two rain-rate thresholds: (a) light rain rate (≤5 mm h−1), and (b) moderate to heavy rain rate (>5 mm h−1). The results suggest that afternoon to evening precipitation is noticed as embedded convection within a large region of light rain over the south-facing slopes of the Himalayas. The moderate to heavy conditional rain rate exhibits a relatively stronger diurnal cycle of precipitation in this region. However, this may be biased because of sampling. Almost all the Tibetan Plateau shows light rain activity.

The Tibetan Plateau and northern Indian subcontinent regions are characterized by daytime maximum precipitation. From the analysis of near-surface rainfall over the finescale topography, it is observed that daytime (1200–1800 LT) precipitation is concentrated over the ridges and strong ridge–valley gradients with rain appearing over the south-facing slopes of the Himalayas. During midnight–early morning, intense rainfall concentrates over the ridges as well as in river valleys. Precipitation broadening and movement are noticed during this time period.
Tracer Advection Using Dynamic Grid Adaptation and MM5
Authors: Iselin John P. , Gutowski William J. , Prusa Joseph M.
Published: March 2005

A dynamic grid adaptation (DGA) technique is used to numerically simulate tracer transport at meso- and regional scales. A gridpoint redistribution scheme is designed to maximize heuristic characteristics of a “good” grid. The advective solver used in conjunction with the DGA is the multidimensional positive definite advection transport algorithm (MPDATA). The DGA results for regional tracer transport are compared against results generated using the leapfrog as well as MPDATA advection schemes with uniformly spaced, static grids. Wind fields for all tracer transport algorithms are provided by the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5). A mesoscale-sized test case with idealized initial condition and wind field clearly shows qualitatively and quantitatively the advantage of using the dynamic adaptive grid, which is a marked reduction in numerical error. These results are further corroborated by more realistic test cases that used NCEP–NCAR reanalysis data from 6–11 March 1992 to set initial and boundary conditions for (i) a mesoscale-sized, 24-h simulation with an idealized initial tracer field, and (ii) a regional, 5-day simulation with water vapor field initialized from the reanalysis data but then treated as a passive tracer. A result of interest is that MPDATA substantially outperforms the leapfrog method with fourth-order artificial dissipation (central to MM5) in all of our test cases. We conclude that with dynamic grid adaptation, results with approximately the same accuracy as a uniform grid may be obtained using only a quarter of the grid points of the uniform grid MPDATA simulations. Compared to results generated using the leapfrog method on a uniform grid, the DGA does even better.
Convective Initiation ahead of the Sea-Breeze Front
Authors: Fovell Robert G.
Published: March 2005

In earlier work, a three-dimensional cloud model was used to simulate the interaction between the sea-breeze front (SBF) and front-parallel horizontal convective rolls (HCRs), resulting in the SBF systematically encountering roll updrafts and downdrafts as it progressed inland. Interestingly, deep convection was spawned above an HCR updraft ahead of the SBF as the front approached, well before the inevitable front–roll merger. Ostensibly, both the sea-breeze and roll circulations were required for deep convection to be present in this case at all because convection was entirely absent when either phenomenon was removed.

Further analysis reveals why both circulations were necessary yet not sufficient for the excitation of deep convection in this case. The sea-breeze circulation (SBC) made its upstream (inland) environment more favorable for convection by bringing about persistent if gentle lifting over an extended region stretching well ahead of the SBF. This persistent ascent established a moist and cool tongue of air, manifested by a visible and/or subvisible cloud feature termed the cloud shelf emanating ahead of the front. Though this lifting moistened and destabilized the environment, the roll’s direct and indirect effects on this moist tongue were also required. The former consisted of a moisture plume lofted by the roll updraft, and the latter consisted of obstacle effect gravity waves generated as the roll drafts penetrated through the top of the boundary layer, into the SBC-associated offshore flow farther aloft. These provided the missing spark, which led to rapid growth of cumulus above the roll updraft, drawing first from air located above the boundary layer.

Once established, deep convection above the roll updraft modulated cloudiness above the approaching SBF, at first suppressing it but subsequently assuring its reestablishment and eventual growth into deep convection, again prior to the front–roll merger. This resulted from the influence of gravity waves excited owing to heating and cooling within the roll cloud.
The Diurnal Cycle of Precipitation in the Tropical Andes of Colombia
Authors: Poveda Germán , Mesa Oscar J. , Salazar Luis F. , Arias Paola A. , Moreno Hernán A. , Vieira Sara C. , Agudelo Paula A. , Toro Vladimir G. , Alvarez J. Felipe
Published: March 2005

Using hourly records from 51 rain gauges, spanning between 22 and 28 yr, the authors study the diurnal cycle of precipitation over the tropical Andes of Colombia. Analyses are developed for the seasonal march of the diurnal cycle and its interannual variability during the two phases of El Niño–Southern Oscillation (ENSO). Also, the diurnal cycle is analyzed at intra-annual time scales, associated with the westerly and easterly phases of the Madden–Julian oscillation, as well as higher-frequency variability (<10 days), mainly associated with tropical easterly wave activity during ENSO contrasting years. Five major general patterns are identified: (i) precipitation exhibits clear-cut diurnal (24 h) and semidiurnal (12 h) cycles; (ii) the minimum of daily precipitation is found during the morning hours (0900–1100 LST) regardless of season or location; (iii) a predominant afternoon peak is found over northeastern and western Colombia; (iv) over the western flank of the central Andes, precipitation maxima occur either near midnight, or during the afternoon, or both; and (v) a maximum of precipitation prevails near midnight amongst stations located on the eastern flank of the central Cordillera. The timing of diurnal maxima is highly variable in space for a fixed time, although a few coherent regions are found in small groups of rain gauges within the Cauca and Magdalena River valleys. Overall, the identified strong seasonal variability in the timing of rainfall maxima appears to exhibit no relationship with elevation on the Andes. The effects of both phases of ENSO are highly consistent spatially, as the amplitude of hourly and daily precipitation diminishes (increases) during El Niño (La Niña), but the phase remains unaltered for the entire dataset. We also found a generalized increase (decrease) in hourly and daily rainfall rates during the westerly (easterly) phase of the Madden–Julian oscillation, and a diminished (increased) high-frequency activity in July–October and February–April during El Niño (La Niña) years, associated, among others, with lower (higher) tropical easterly wave (4–6 day) activity over the Caribbean.
The 30 May 1998 Spencer, South Dakota, Storm. Part II: Comparison of Observed Damage and Radar-Derived Winds in the Tornadoes
Authors: Wurman Joshua , Alexander Curtis R.
Published: March 2005

A violent supercell tornado passed through the town of Spencer, South Dakota, on the evening of 30 May 1998 producing large gradients in damage severity. The tornado was rated at F4 intensity by damage survey teams. A Doppler On Wheels (DOW) mobile radar followed this tornado and observed the tornado at ranges between 1.7 and 8.0 km during various stages of the tornado's life. The DOW was deployed less than 4.0 km from the town of Spencer between 0134 and 0145 UTC, and during this time period, the tornado passed through Spencer, and peak Doppler velocity measurements exceeded 100 m s−1. Data gathered from the DOW during this time period contained high spatial resolution sample volumes of approximately 34 m × 34 m × 37 m along with frequent volume updates every 45–50 s.

The high-resolution Doppler velocity data gathered from low-level elevation scans, when sample volumes are between 20 and 40 m AGL, are compared to extensive ground and aerial damage surveys performed by the National Weather Service (NWS) and the National Institute of Standards and Technology (NIST). Idealized radial profiles of tangential velocity are computed by fitting a model of an axisymmetric translating vortex to the Doppler radar observations, which compensates for velocity components perpendicular to the radar beam as well as the translational motion of the tornado vortex.

Both the original single-Doppler velocity data and the interpolated velocity fields are compared with damage survey Fujita scale (F-scale) estimates throughout the town of Spencer. This comparison on a structure-by-structure basis revealed that radar-based estimates of the F-scale intensity usually exceeded the damage-survey-based F-scale both inside and outside the town of Spencer. In the town of Spencer, the radar-based wind field revealed two distinct velocity time series inside and outside the passage of the core-flow region. The center of the core-flow region tracked about 50 m farther north than the damage survey indicated because of the asymmetry induced by the 15 m s−1 translational motion of the tornado. The radar consistently measured the strongest winds in the lowest 200 m AGL with the most extreme Doppler velocities residing within 50 m AGL. Alternate measures of tornado wind field intensity that incorporated the effects of the duration of the extreme winds and debris were explored. It is suggested that damage may not be a simple function of peak wind gust and structural integrity, but that the duration of intense winds, directional changes, accelerations, and upwind debris loading may be critical factors.
A Local Energetics Analysis of the Life Cycle Differences between Consecutive, Explosively Deepening, Continental Cyclones
Authors: Decker Steven G. , Martin Jonathan E.
Published: March 2005

Local energetics diagnostics of the life cycles of consecutive, explosively deepening, extratropical cyclones that migrated across central North America in April 2001 are presented. Both storms developed rapidly and followed nearly identical tracks through the region. Despite similar mature-stage intensities, the two storms underwent vastly different evolutions during cyclolysis; the first decayed as rapidly as it had developed, and the second decayed very slowly. Examination of the volume-integrated eddy kinetic energy (EKE) budget for each storm reveals that the sea level pressure minimum associated with the first cyclone developed well after its associated EKE center had reached its maximum intensity. In contrast, the second cyclone’s sea level pressure minimum developed much more in concert with the development of its associated EKE center. As a consequence, the first cyclone began losing EKE through downstream energy fluxes even as it was developing at the surface, whereas the second cyclone did not disperse EKE downstream until later in its life cycle. Consideration of the EKE budget results in terms of baroclinic wave packets demonstrates that the first cyclone developed and decayed on the upstream edge of a wave packet, whereas the second cyclone developed in the midst of a wave packet, only decaying once it had reached the upstream edge. Thus, it is suggested that postmature phase decay is dynamically linked to a cyclone’s position in a given wave packet.
Incorporating State-Dependent Temperature–Salinity Constraints in the Background Error Covariance of Variational Ocean Data Assimilation
Authors: Ricci S. , Weaver A. T. , Vialard J. , Rogel P.
Published: March 2005

Several studies have illustrated how the univariate assimilation of temperature data can have a detrimental effect on the ocean-state variables (salinity, currents, etc.) not directly constrained by the data. In this paper, the authors describe how the salinity adjustment method proposed by Troccoli and Haines can be included as a multivariate temperature–salinity (T–S) constraint within a background-error covariance model for variational data assimilation. The method is applied to a three-dimensional variational assimilation (3DVAR) system for a tropical Pacific version of the Océan Parallélisé (OPA) ocean general circulation model. An identical twin experiment is presented first to illustrate how the method is effective in reconstructing a density profile using only temperature observations from that profile. The 3DVAR system is then cycled over the period 1993–98 using in situ temperature data from the Global Temperature and Salinity Pilot Programme. Relative to a univariate (T) 3DVAR, the multivariate (T, S) 3DVAR significantly improves the salinity mean state. A comparison with salinity data that are not assimilated is also presented. The fit to these observations is improved when the T–S constraint is applied. The salinity correction leads to a better preservation of the salinity structure and avoids the development of spurious geostrophic currents that were evident in the univariate analysis. The currents at the surface and below the core of the undercurrent are also improved.

Examination of the heat budget highlights how the temperature increment must compensate for a perpetual degradation of the temperature field by abnormally strong advection in the univariate experiment. When the T–S constraint is applied, this spurious advection is reduced and the mean temperature increment is decreased. Examination of the salt budget shows that spurious advection is also the main cause of the upper-ocean freshening. When the T–S constraint is applied, the salinity structure is improved allowing for a better representation of the advection term and better preservation of the salt content in the upper ocean. The T–S constraint does not correct for all problems linked to data assimilation: vertical mixing is still too strong, and the surface salinity state and currents still have substantial errors. Improvements can be expected by including additional constraints in the background error covariances and by assimilating salinity data.
Personal Care Aide Turnover in Residential Care Settings: An Assessment of Ownership, Economic, and Environmental Factors
Authors: Konetzka R. Tamara , Stearns Sally C. , Konrad T. Robert , Magaziner Jay , Zimmerman Sheryl
Published: March 2005

Turnover among personal care aides is a chronic problem facing long-term-care industries. High turnover leads to high recruitment and training costs and to the potential for substandard care. Studies in nursing homes have found environmental factors to be more important than economic factors in predicting turnover rates, but no studies have been done in an assisted living setting or have considered the effects of the physical environment and location of the facility. This study assesses the importance of a variety of factors on turnover among personal care aides, using a two-part model. The results show that certain ownership and environmental factors (facility type, chain ownership, and attractiveness of the neighborhood)are important predictors of turnover. Although adequate economic compensation is undoubtedly important in attracting and retaining qualified staff, the results identify facility characteristics that may indicate a greater level of turnover as well as greater potential for improvement through interventions to reduce turnover.
A Professional Development Program in Geriatric Interdisciplinary Teamwork: Implications for Managed Care and Quality of Care
Authors: Coogle Constance L. , Parham Iris A. , Cotter J. James , Welleford E. Ayn , Netting F. Ellen
Published: March 2005

This study investigated the effectiveness of a multiyear geriatric interdisciplinary team training (ITT) program conducted by a geriatric education center in cooperation with three large health care systems. Approximately 40 half-day training sessions were planned and implemented by the university-community partnership. The training sessions included core content on team processes and substantive clinical material on geriatric concerns and disease states (dementia, diabetes, etc.). Statistical analyses revealed that a critical amount of training is necessary to induce positive changes in team skills and attitudes about geriatric health care teams. Results also indicated that maturity, practical experience, and some previous formal training in geriatrics or gerontology are predisposing factors contributing to the effectiveness of geriatric ITT. Because resources to implement these kinds of comprehensive training programs are often limited, more focused educational interventions are advisable.
Family Caregiver Involvement and Satisfaction With Institutional Care During the 1st Year After Admission
Authors: Levy-Storms Lené , Miller-Martinez Dana
Published: March 2005

The purpose of this research is to examine the relationship between caregivers’ involvement and their satisfaction with institutional care during the 1st year. This panel study includes 145 care-givers. A summary indicator of satisfaction was analyzed (a) near admission and (b) for change 1 year after admission. Caregivers were least satisfied with physicians and the number of staff at both time points. Satisfaction at admission and change in satisfaction from admission to 1 year later were regressed on caregivers’ involvement after controlling for caregivers’ depression, family tension, and perceived behavioral problems of their relatives. Multivariate results indicated that more involved caregivers at admission were less satisfied with institutional care at admission and became less satisfied during the year after admission. More involved caregivers may be less satisfied because they see firsthand problems with nursing home care and because a meaningful caregiving role after institutionalization is not facilitated by nursing homes.
Caregiver Psychological Adjustment and Institutionalization of Persons With Alzheimer’s Disease
Authors: Gilley David W. , McCann Judith J. , Bienias Julia L. , Evans Denis A.
Published: March 2005

This prospective study examines the relationship between caregiver psychological adjustment and institutionalization of persons with Alzheimer’s disease (AD). Method: A 3-year longitudinal study was conducted with a clinic-based cohort of 396 persons with AD and their respective family caregivers. Caregiver adjustment was sequentially measured in 3-month intervals using standard scales of appraisal (perceived burden and satisfaction) and emotion (depressive symptoms and positive affect). Results: In multivariable proportional hazards regression models predicting time to institutionalization controlling for AD severity, hazard ratios were significant for appraisal measures of caregiver adjustment, perceived burden (1.053; 95% confidence interval [CI], 1.014, 1.093), and satisfaction (.929; 95% CI, .883, .977). In contrast, levels of caregivers’ positive and negative emotion did not reliably predict institutionalization. Discussion: The findings highlight the importance of caregiver appraisals in decisions to institutionalize persons with a dementia syndrome, but the limited impact of caregiver emotion was unexpected and requires further study.
Factors Affecting Choice of Community Residential Care Setting
Authors: Sales A. E. , Hedrick S. C. , Sullivan J. , Gray S. L. , Curtis M. , Tornatore J.
Published: March 2005

To investigate factors associated with residents’ choice of type of Medicaid-funded community residential care setting in western Washington State. Method: Prospective cohort design including residents new to any of three setting types (264 residents entering 170 different facilities), using data from state and Medicaid databases and in-person interviews. The authors used analysis of variance and multinomial logistic regression to examine bivariate associations and estimate effects of resident and facility characteristics on choice of facility type at baseline. Results: Several resident characteristics appear to be associated with choice of community residential care setting, including age, marital status, education, functional status, and reported memory and behavior problems. Facility policies differ significantly among types of facilities and also appear to be associated with choice of setting. Discussion: Selection processes operate in choice of community residential care setting, with residents choosing facility type based on the fit of their needs with facility characteristics.
Discretionary Hospitalization of Nursing Home Residents With and Without Alzheimer’s Disease
Authors: Porell Frank W. , Carter Mary
Published: March 2005

This study analyzes facility variations in hospital admission rates of nursing home (NH) residents with and without Alzheimer’s disease (AD) or related dementia with the aim of better understanding how facility-level contextual factors differentially affect hospitalization risks. Method: The sample population consists of 19,217 and 18,399 Medicaid residents with and without AD, respectively, from 546 NHs in Massachusetts between 1991 and 1993. Hospital use is measured as annual nonpsychiatric discretionary hospital admissions to short-term general hospitals. Multilevel estimation methods are used to obtain facility and market area parameter estimates. Results: There was greater interfacility variation in discretionary hospital admission rates of AD residents than residents without AD, particularly among more vulnerable subgroups of AD residents. Discussion: The findings underscore the importance of licensed nursing personnel in reducing discretionary hospitalizations among NH residents with AD.
Modifiable Impairments Predict Progressive Disability Among Older Persons
Authors: Tinetti Mary E. , Allore Heather , Araujo Katy L. B. , Seeman Teresa
Published: March 2005

Our purpose was to determine the extent to which a predetermined set of modifiable impairments predicted progression of disability. Method: We conducted a 3-year follow-up of two community-based cohorts of older adults. The impairment areas included lower extremity, upper extremity, hearing, vision, and affect. Home management and social or productive activities were the domains of function investigated. Results: All five impairments were of at least borderline significance in predicting decline in both functional domains in both cohorts with the exception of hearing for home management activities. The five impairments together explained from 17% to 23% of the decline seen in the functional outcomes (partial R2s 0.17 to 0.23). Discussion: Five prevalent and potentially modifiable impairments explained much of the progressive disability experienced. Given the priority that older patients place on function as a health outcome, these impairments should be routinely assessed and modified.
Radiation Effects on Thermal Properties of Polymers. I. Polyethylene (contd.)
Authors: Briskman Boris A. , Tlebaev Kayrat B.
Published: March 2005

The information about radiation effects on the thermal properties of polymeric materials is of special interest as: (1) the temperature regime of technical structural units operated in the radiation fields is determined in many respects by the values of the material thermal constants and the rate of their degradation (2) the temperature and dose dependencies of heat conductivity and, especially, heat capacity characterize the polymer structure. The data on radiation effects on the thermal conductivity, heat capacity and diffusivity, linear thermal expansion, density, degree of crystallinity, heat and temperature of phase transitions were presented in the first part of this paper [ Nucl. Instr. Meth. in Phys. Res. B 185 (2001) 116–122] for polyethylene of high and low density, as a well-known and typical partly-crystalline polymer that is very convenient for investigation of the radiolysis processes. This part of the review examines such problems as reversible radiation effects on heat capacity, analytical models of the radiation-induced changes and anisotropy effects on the thermal conductivity, accumulated radiation energy (‘heat defect’) and important problems of specific action of different kinds of radiation on the thermal properties of the polymer and dose-rate effects, especially under vacuum.