bluuebunny/crossref_metadata_2025 huggingface dataset:
The humble electrocardiogram
Authors: Marsh Eleanor , O’Callaghan Peter , Smith Philip
Published: July 2008

Many patients with potentially life-threatening cardiac conditions presenting with transient loss of consciousness are referred first to neurology clinics. Therefore, neurologists must remain competent to interpret electrocardiograms (ECGs) and in particular be able to identify those rare conditions that predict sudden cardiac death. A 12-lead ECG is cheap and readily available, and can give essential diagnostic information. Here the authors review abnormalities in, and indications for, the ECG in neurological practice.
A practical approach to acute vertigo
Authors: Seemungal B M , Bronstein A M
Published: July 2008

Patients complaining of symptoms of acute vertigo present a diagnostic challenge for the clinician; the main differential diagnoses are acute unilateral peripheral vestibulopathy (“vestibular neuritis”), cerebellar stroke or migraine. The head impulse test is useful in the acute situation because, of these three diagnostic alternatives, it will only be positive in patients with vestibular neuritis. A history of acute vertigo and hearing loss suggests Ménière’s disease but the clinician must be wary of anterior inferior cerebellar artery strokes which may cause audiovestibular loss due to peripheral vestibulocochleal ischaemia, although the accompanying brainstem signs should remove diagnostic ambiguity. We also discuss other less common vertigo diagnoses that may be referred to the neurologist from the acute general hospital take. As ever in neurology, a careful history and focussed examination is necessary in the evaluation and management of acute vertigo.
Comparative growth and survival patterns of Mytilus trossulus and Mytilus edulis in Atlantic Canada
Authors: Mallet André L. , Carver Claire E.
Published: July 2008

Two size groups (20–30 and 45–55 mm) of Mytilus edulis and Mytilus trossulus were assessed from May to December 1992 at two locations in Nova Scotia. The two species were classified using electrophoresis based on mannose phosphate isomerase, and a discriminant function based on shell morphometry. The discriminant function misclassified less than 5% of the mussels and of these, 1% of the M. edulis were misclassified as M. trossulus, and 10% of the M. trossulus were misclassified as M. edulis. In general, both size groups of M. edulis tended to have higher shell growth rates than M. trossulus. Overall mortality was 6% and occurred primarily from mid-August to mid-September; M. edulis exhibited a slightly lower survival and for a given shell length had a higher average tissue and shell weight, as well as a greater shell height, than M. trossulus. Mytilus trossulus had a significantly lower tissue weight during the summer and was eliminated at a significantly higher rate during commercial grading trials than M. edulis. We estimated from the information on individual weight, survival, and grading losses that the economic value of M. edulis was 1.7 times higher than that of M. trossulus.
Effort control in the New England groundfish fishery: a bioeconomic perspective
Authors: Overholtz William J. , Edwards Steven F. , Brodziak Jon K. T.
Published: July 2008

A multispecies model of the New England fishery was developed to investigate selected biological and economic implications of effort control on groundfish. Performance measures, such as catch, spawning stock biomass, and catch per unit effort, as well as harvest revenue and consumer surplus were used to compare and contrast different levels of effort. Results suggest that significant gains in biological and economic benefits are possible, but major reductions in effort and some short-term losses in catch would be required. Large increases in catch per unit effort on the order of 3–5 times current values would occur, especially for flatfish and haddock. Additional revenues of approximately $10–13 million (U.S.) per year would accrue after several years with overall reductions in effort on this complex of stocks. Changes in stock age-structure would contribute to additional revenues because of the interaction of fish size, price, and increased biomass. Consumers would eventually profit from the lower prices that accompany increased landings. Additional benefits may be obtained after stock rebuilding occurs by application of management measures that stockpile biomass in the initial years of a planning horizon and harvest accumulated stock later.
Application of a one-dimensional model to vertical distributions of cod eggs on the northeastern Newfoundland Shelf
Authors: Anderson John T. , Young Brad de
Published: July 2008

A one-dimensional model is developed to describe the vertical distribution of cod eggs and larvae on the northeastern Newfoundland Shelf. The model is dependent on egg buoyancy, temperature-dependent development, and age-dependent changes in density for eggs in good and poor condition. The model was fit to physical oceanographic data from the inner and outer shelf collected in 1991. Output from the model compared favourably with field observations. Cod eggs (stages I to III) were bimodally distributed above and below 100 m depth. Late stage eggs (stage IV) and larvae (5–6 mm) were only abundant in surface waters (<50 m). There was a progression from deeper to shallower depths as cod eggs developed through to larvae. Cod eggs observed deeper in the water column were thought to be in poor condition and were probably sinking. The model demonstrates that the vertical distribution of cod eggs is sensitive to changes in water temperature, water density (salinity), and egg condition.
Metals-contaminated benthic invertebrates in the Clark Fork River Montana: effects on age-0 brown trout and rainbow trout
Authors: Woodward Daniel F. , Farag Aïda M. , Bergman Harold L. , DeLonay Aaron J. , Little Edward E. , Smiths Charlie E. , Barrows Frederic T.
Published: July 2008

Benthic organisms in the upper Clark Fork River have recently been implicated as a dietary source of metals that may be a chronic problem for young-of-the-year rainbow trout (Oncorhynchus mykiss). In this present study, early life stage brown trout (Salmo trutta) and rainbow trout were exposed for 88 d to simulated Clark Fork River water and a diet of benthic invertebrates collected from the river. These exposures resulted in reduced growth and elevated levels of metals in the whole body of both species. Concentrations of As, Cd, Cu, and Pb increased in whole brown trout; in rainbow trout, As and Cd increased in whole fish, and As also increased in liver. Brown trout on the metals-contaminated diets exhibited constipation, gut impaction, increased cell membrane damage (lipid peroxidation), decreased digestive enzyme production (zymogen), and a sloughing of intestinal mucosal epithelial cells. Rainbow trout fed the contaminated diets exhibited constipation and reduced feeding activity. We believe that the reduced standing crop of trout in the Clark Fork River results partly from chronic effects of metals contamination in benthic invertebrates that are important as food for young-of-the-year fish.
Preservation of broadleaf species in Korean pine (Pinus koraiensis) plantations affects soil properties, carbon storage, biomass allocation, and available nitrogen storage
Authors: Li Xuefeng , Han Shijie
Published: July 2008

We analyzed forest floor mass, soil properties, soil organic carbon (SOC) storage, soil available nitrogen (NO3–-N and NH4+-N) (SAN) storage, litter production and decomposition, tree biomass, and the growth rate of Korean pine ( Pinus koraiensis Sieb. et Zucc.) to determine the impacts of keeping broadleaf species in the Korean pine plantation on Korean pine growth and identify the interactions of plants and soil. Forest biomass and litter production were significantly higher in the broadleaf mixed Korean pine plantation (KBP) than in the pure Korean pine plantation (KP). Broadleaf species redistributed carbon from forest floor to mineral soil via its fast litter decomposition rate with the result of a smaller forest floor mass and a greater SOC storage in KBP than in KP. KBP had significantly higher SOC and SAN storages, SOC and SAN concentrations, and pH, and lower soil bulk density than KP. Such differences can be largely explained by the input of broadleaf litter into KBP. The Korean pine in KBP had a greater growth rate and allocated a smaller proportion of biomass below ground, indicating that the broadleaf species influenced the Korean pine growth and biomass allocation pattern by changing soil properties. There was a positive feedback among litter N release rate, SAN storage, and plant growth rates.
How promptly nonindustrial private forest landowners regenerate their lands after harvest: a duration analysis
Authors: Sun Xing , Munn Ian A. , Sun Changyou , Hussain Anwar
Published: July 2008

Understanding factors that influence how promptly landowners regenerate their timberlands after harvest, if at all, is critical to developing policies to improve forest productivity. Mississippi forest landowners with over 100 acres (1 acre = 0.404 ha) of forestland were surveyed in 2006 to collect harvest and regeneration data from 1996 to 2006. This study investigated the length of the time interval between harvest and reforestation. Nonparametric duration analysis was used to examine how long nonindustrial private forest landowners waited to reforest after harvesting. Parametric duration analysis was used to examine factors that influenced the length of this period. The mean time elapsed from harvest to regeneration was 11 months for landowners that regenerated their lands. The instantaneous probability of regeneration reached its highest value in the 16th month after harvest and, thereafter, decreased steadily until the 28th month, after which the probability of regeneration was essentially nil. Interest in timber production, employing a consultant, and ownerships that were predominantly pine forest types were factors associated with substantially shorter reforestation times. Lower stumpage prices and higher reforestation costs were associated with substantially longer reforestation times.
Water table depth affects productivity, water use, and the response to nitrogen addition in a savanna system
Authors: Ford Chelcy R. , Mitchell Robert J. , Teskey Robert O.
Published: July 2008

We investigated annual aboveground net primary productivity (ANPP) and transpiration (E) of the dominant plant life forms, longleaf pine (Pinus palustris Mill.) trees and wiregrass (Aristida stricta Michx.), in a fire-maintained savanna. Experimental plots spanned a natural hydrologic gradient (xeric and mesic site types) mediated by soil moisture (θ) and water table depth (WTD), and received additions of either 0 or 100 kg N·ha–1·year–1. Low rates of ANPP (1.3–2.2 Mg·ha–1) and annual E (108–380 mm) were observed in these communities. WTD and N addition explained 95% of the variation in community ANPP, whereas site type and WTD explained 83% of variation in community E. Between tree and grass life forms, longleaf pine ANPP was more coupled to WTD than wiregrass. For any given leaf area supported, ANPP of longleaf pine increased linearly with increasing water use and decreasing WTD. The longleaf pine ANPP response to N addition was greater in sites with high water use compared with those with low water use, indicating that this savanna system is colimited by nutrient and water availability and that water table depth plays a role in regulating savanna productivity.
Aerobiology of Pinus taeda pollen clouds
Authors: Williams Claire G.
Published: July 2008

Better knowledge of aerobiological properties of pollen clouds is needed for pines and other woody perennials because these properties shape the predictive accuracy of spatially explicit pollen dispersal models. Four properties were experimentally measured in this study using processed Pinus taeda L. (loblolly pine) pollen as well as pollen concentration and viability data collected from an 18-year-old P. taeda plantation. Results showed that P. taeda pollen had a settling or terminal velocity value of 2.1 cm·s–1; that daytime pollen count from a plantation was sparse, reaching a maximum of 1480 grains·m–3 at peak pollen shed; and that pollen concentration showed no vertical gradient above or below the plantation’s canopy. Pollen sampled above and within the canopy had comparable germination rates. Surprisingly, a low concentration of viable Pinus spp. pollen was present during nighttime. Study results added further to the idea that P. taeda pollen has a higher nuisance value than either Zea mays L. (maize) or Agrostis stolonifera L. (creeping bentgrass) pollen because of its low terminal velocity value, persistent viability, and perennial production.
Accounting for error correlations in diameter increment modelling: a case study applied to northern hardwood stands in Quebec, Canada
Authors: Fortin Mathieu , Bédard Steve , DeBlois Josianne , Meunier Sébastien
Published: July 2008

In this study, a diameter increment model was calibrated for individual trees in hardwood stands in Quebec, Canada. Two random effects, a first one for the plot and a second one for the time interval nested in the plot, and a covariance structure were included in the model to account for spatial and serial correlations. The diameter at breast height, species group, vigor and product classes, and basal area were the explanatory variables that were tested in this analysis. The adequacy of the covariance features (random effects and covariance structure) were tested through empirical correlations calculated from normalized residuals. A cross-validation was also carried out to evaluate the model. The normalized residuals showed no departure from the assumption of independently and normally distributed error terms with homogeneous variances. Consequently, the statistical inferences could be considered as valid. The results showed that the average diameter increment pattern differs among the species. Although tree product and vigor were significant explanatory variables, their effects were relatively small. On the other hand, basal area had a large and significant negative effect on diameter increment. Our study demonstrates that empirical correlations calculated from normalized residuals can be used as an additional tool to test the adequacy of the covariance features in a mixed-effects model.
Malonyl-CoA, a Key Signaling Molecule in Mammalian Cells
Authors: Saggerson David
Published: July 2008

Malonyl-CoA can be formed within the mitochondria, peroxisomes, and cytosol of mammalian cells. Besides being an intermediate in the pathways of de novo fatty acid biosynthesis and fatty acid elongation, malonyl-CoA has an important signaling function through its allosteric inhibition of carnitine palmitoyltransferase 1, the enzyme that normally exerts flux control over mitochondrial β-oxidation. Malonyl-CoA is rapidly turned over in mammalian cells, and the activities of acetyl-CoA carboxylase and malonyl-CoA decarboxylase are important determinants of its cytosolic concentration. It is now recognized that malonyl-CoA participates in a diverse range of physiological or pathological responses and systems. These include the ketogenic response of the liver to fasting and diabetes, carbohydrate versus fat fuel selection in muscle tissues, metabolic changes in muscle during contracture, alterations in fatty acid metabolism during cardiac ischemia and postischemic reperfusion, stimulation of B cell insulin secretion by glucose, and the hypothalamic control of appetite.
Metformin normalizes endothelial function by suppressing vasoconstrictor prostanoids in mesenteric arteries from OLETF rats, a model of type 2 diabetes
Authors: Matsumoto Takayuki , Noguchi Eri , Ishida Keiko , Kobayashi Tsuneo , Yamada Nobuhiro , Kamata Katsuo
Published: July 2008

We previously reported that in mesenteric arteries from aged Otsuka Long-Evans Tokushima fatty (OLETF) rats (a type 2 diabetes model) endothelium-derived hyperpolarizing factor (EDHF)-type relaxation is impaired while endothelium-derived contracting factor (EDCF)-mediated contraction is enhanced (Matsumoto T, Kakami M, Noguchi E, Kobayashi T, Kamata K. Am J Physiol Heart Circ Physiol 293: H1480–H1490, 2007). Here we investigated whether acute and/or chronic treatment with metformin might improve this imbalance between the effects of the above endothelium-derived factors in mesenteric arteries isolated from OLETF rats. In acute studies on OLETF mesenteric arteries, ACh-induced relaxation was impaired and the relaxation became weaker at high ACh concentrations. Both metformin and 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside [AICAR, an AMP-activated protein kinase (AMPK) activator that is also activated by metformin] 1) diminished the tendency for the relaxation to reverse at high ACh concentrations and 2) suppressed both ACh-induced EDCF-mediated contraction and ACh-stimulated production of prostanoids (thromboxane A2and PGE2). In studies on OLETF arteries from chronically treated animals, metformin treatment (300 mg·kg−1·day−1for 4 wk) 1) improved ACh-induced nitric oxide- or EDHF-mediated relaxation and cyclooxygenase (COX)-mediated contraction, 2) reduced EDCF-mediated contraction, 3) suppressed production of prostanoids, and 4) reduced superoxide generation. Metformin did not alter the protein expressions of endothelial nitric oxide synthase (eNOS), phospho-eNOS (Ser1177), or COX-1, but it increased COX-2 protein. These results suggest that metformin improves endothelial functions in OLETF mesenteric arteries by suppressing vasoconstrictor prostanoids and by reducing oxidative stress. Our data suggest that within the timescale studied here, metformin improves endothelial function through this direct mechanism, rather than by improving metabolic abnormalities.
Selective Growth of α‐Al2O3 Nanowires and Nanobelts
Authors: Zhang Yong , Li Ruying , Zhou Xiaorong , Cai Mei , Sun Xueliang
Published: July 2008

We report the selective growth of α‐Al2O3 nanowires and nanobelts via a catalyst‐free chemical vapor deposition process under ambient pressure. By controlling the flow rates of the carrier gas, high‐yield production of uniform alumina nanowires with diameter distribution (100 nm–200 nm) was achieved at a high growth rate over 200 μm/hour. Alumina nanobelts with variable width were also synthesized by modulating the carrier gas purge process. Further, the effects of temperatures and carrier gas flow rates on the growth of alumina nanostructures were also investigated. Oxygen partial pressure and supersaturation level of the aluminum suboxide are thought to be important factors in the formation process of the alumina nanowires or nanobelts. The typical growth of the alumina nanowires and nanobelts can be ascribed to vapor‐solid (VS) mechanism.
Vesicoureteral Reflux and Duplex Systems
Authors: Thomas John C.
Published: July 2008

Vesicoureteral reflux (VUR) is the most common anomaly associated with duplex systems. In addition to an uncomplicated duplex system, reflux can also be secondary in the presence of an ectopic ureterocele with duplex systems. Controversy exists in regard to the initial and most definitive management of these anomalies when they coexist. This paper will highlight what is currently known about duplex systems and VUR, and will attempt to provide evidence supporting the various surgical approaches to an ectopic ureterocele and duplex system and the implications of concomitant VUR.
Experiences from a Touch-Based Interaction and Digitally Enhanced Meal-Delivery Service for the Elderly
Authors: Isomursu Minna , Häikiö Juha , Wallin Arto , Ailisto Heikki
Published: July 2008

This paper reports the results of a field experiment where home-dwelling elderly people used a mobile technology-based service to interact with a home care service to order meals to be delivered to their homes. The primary research focus was on examining the suitability of touch-based interaction in the everyday life activities of elderly users. The eight-week experiment took place in the autumn of 2006. The findings are based primarily on user experience and on the socioeconomic analysis done from the data collected before, during, and after the experiment. The results show that touch-based interaction was easy to learn and adopt, and that the users were able to successfully use it regardless of their physical or cognitive weaknesses. However, the socioeconomic value of the service was questionable. The paper also summarises methodological issues and findings related to user experience evaluation in an experimental setting.
Composing Music and the Science of the Heart: How to Serve Two Masters
Authors: Bing Richard J.
Published: July 2008

The author, both a composer and a physician, chronicles his development as a musician—from his childhood fascination with improvising on the piano to the eventual performance of one of his compositions in the church of Saint Stefan in Vienna—and his career as a medical doctor studying heart disease and researching new cures. He finds that the common denominator in composing music and doing medical research is the creative impulse. In his life, music and medicine have never been in competition. Rather, when frustrated by difficulties in medical research, the author has found renewal in composing music.
The Low-Frequency Relationship of the Tropical–North Pacific Sea Surface Temperature Teleconnections
Authors: Yeh Sang-Wook , Kirtman Ben P.
Published: July 2008

The low-frequency relationship between interannual tropical and North Pacific sea surface temperature anomalies (SSTAs) in observations and a coupled general circulation model (CGCM) is investigated. The authors use the interactive ensemble CGCM, which advances a new approach for artificially increasing the signal-to-noise ratio, making it easier to detect physical and dynamical links with much reduced interference by atmospheric noise. The results presented here suggest that decadal variations in the relationship between the dominant modes of tropical and North Pacific interannual SSTA variability result from changes of spatial manifestation of North Pacific SSTA, both in the observation and in the model.

The authors conjecture that the details of tropical Pacific SST forcing ultimately determine the tropical–North Pacific SST teleconnections, and this conjecture is examined in a much longer time series from a CGCM simulation. There are two patterns of North Pacific interannual SSTA variability in the model. The first pattern is locally forced by noise in the surface air–sea fluxes associated due to internal atmospheric dynamics. The second pattern is remotely forced by tropical SSTA. As the relationship of tropical–North Pacific SST teleconnections varies in the model, the spatial manifestation of the North Pacific SSTA changes from the atmospheric noise-forced pattern to the remotely forced pattern and vice versa. In the model, the amplitude of the tropical Pacific SSTA variance varies on decadal time scales and this largely determines the dominant structure of North Pacific SSTA variability. Furthermore, the change in location of the maximum tropical SST forcing is associated with the changes in the spatial manifestation of North Pacific interannual SSTA variability.
Shallow Meridional Circulations in the Tropical Atmosphere
Authors: Zhang Chidong , Nolan David S. , Thorncroft Christopher D. , Nguyen Hanh
Published: July 2008

A shallow meridional circulation (SMC) in the tropical atmosphere features a low-level (e.g., 700 hPa) flow that is in the opposite direction to the boundary layer monsoon or trade wind flow and is distinct from the meridional flow above. Representations of the SMC in three global reanalyses show both similarities and astonishing discrepancies. While the SMC over West Africa appears to be the strongest, it also exists over the eastern Atlantic and eastern Pacific Oceans, and over the Indian subcontinent, with different strength and structure. All SMCs undergo marked seasonal cycles. The SMCs are summarized into two types: one associated with the marine ITCZ and the other with the summer monsoon. The large-scale conditions for these two types of SMCs are similar: a strong meridional gradient in surface pressure linked to surface temperature distributions and an absence of deep moist convection. The processes responsible for these conditions are different for the two types of SMCs, as are their structures relative to moist convection, associated precipitation, and deep meridional overturning circulations. It is suggested that discrepancies among the representations of the SMC in the three global reanalyses stem from different treatment of physical parameterizations, especially for cumulus convection, in the models used for the data assimilation.
Two Regimes of the Equatorial Warm Pool. Part I: A Simple Tropical Climate Model
Authors: Watanabe Masahiro
Published: July 2008

Atmosphere–ocean coupled processes responsible for generating and maintaining the equatorial warm pool were investigated using models of different complexities. The primary focus was to answer the following question: why is the observed warm pool concentrated around the maritime continent? In this first of a two-part series, the solutions of a simple conceptual model that represents the tropical Pacific and Indian Oceans interacting via the Walker circulation are examined. When the interbasin coupling is sufficiently strong, surface wind convergence over the Maritime Continent associated with easterly trades over the Pacific acts to generate the equatorial westerly over the Indian Ocean, leading to a warm pool spontaneously emerging between the two ocean basins. The conceptual model shows that tropical climate has two equilibria, depending upon the ocean basin widths—a single warm pool regime corresponding to the current climate and a split warm pool regime that accompanies warm pools created in the western parts of each ocean basin. The latter is found to be unstable and hence exhibits large-amplitude vacillations between the ocean basins being further amplified by the Bjerknes feedback. The above two regimes of the equatorial warm pool are identified in the model incorporating the interactive Atlantic Ocean as well, wherein the mean state and variability in the three ocean basins qualitatively agree with the observations.
Reduced Atlantic Storminess during Last Glacial Maximum: Evidence from a Coupled Climate Model
Authors: Li Camille , Battisti David S.
Published: July 2008

The Last Glacial Maximum (LGM), 21 000 yr before present, was the time of maximum land ice extent during the last ice age. A recent simulation of the LGM climate by a state-of-the-art fully coupled global climate model is shown to exhibit strong, steady atmospheric jets and weak transient eddy activity in the Atlantic sector compared to today’s climate. In contrast, previous work based on uncoupled atmospheric model simulations has shown that the LGM jets and eddy activity in the Atlantic sector are similar to those observed today, with the main difference being a northeastward extension of their maxima. The coupled model simulation is shown to agree more with paleoclimate proxy records and thus is taken as the more reliable representation of LGM climate. The existence of this altered atmospheric circulation state during LGM in the model has implications for understanding the stability of glacial climates, for the possibility of multiple atmospheric circulation regimes, and for the interpretation of paleoclimate proxy records.
A High-Resolution Simulation of Typhoon Rananim (2004) with MM5. Part I: Model Verification, Inner-Core Shear, and Asymmetric Convection
Authors: Li Qingqing , Duan Yihong , Yu Hui , Fu Gang
Published: July 2008

In this study, the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) is used to simulate Typhoon Rananim (2004) at high resolution (2-km grid size). The simulation agrees well with a variety of observations, especially for intensification, maintenance, landfall, and inner-core structures, including the echo-free eye, the asymmetry in eyewall convection, and the slope of the eyewall during landfall. The asymmetric feature of surface winds is also captured reasonably well by the model, as well as changes in surface winds and pressure near the storm center.

The shear-induced vortex tilt and storm-relative asymmetric winds are examined to investigate how vertical shear affects the asymmetric convection in the inner-core region. The inner-core vertical shear is found to be nonunidirectional, and to induce a nonunidirectional vortex tilt. The distribution of asymmetric convection is, however, inconsistent with the typical downshear-left pattern for a deep-layer shear. Qualitative agreement is found between the divergence pattern and the storm-relative flow, with convergence (divergence) generally associated with asymmetric inflow (outflow) in the eyewall. The collocation of the inflow-induced lower-level convergence in the boundary layer and the lower troposphere and the midlevel divergence causes shallow updrafts in the western and southern parts of the eyewall, while the deep and strong upward motion in the southeastern portion of the eyewall is due to the collocation of the net convergence associated with the strong asymmetric flow in the midtroposphere and the inflow near 400 hPa and its associated divergence in the outflow layer above 400 hPa.
Comparison of Four Cloud Schemes in Simulating the Seasonal Mean Field Forced by the Observed Sea Surface Temperature
Authors: Shimpo Akihiko , Kanamitsu Masao , Iacobellis Sam F. , Hong Song-You
Published: July 2008

The impacts of four stratiform cloud parameterizations on seasonal mean fields are investigated using the global version of the Experimental Climate Prediction Center (ECPC) global-to-regional forecast system (G-RSM). The simulated fields are compared with the International Satellite Cloud Climatology Project (ISCCP) data for clouds, the Global Precipitation Climatology Project data for precipitation, the Earth Radiation Budget Experiment and the Surface Radiation Budget data for radiation, and the National Centers for Environmental Prediction (NCEP)–Department of Energy (DOE) Atmospheric Model Intercomparison Project (AMIP-II) Reanalysis (R-2) for temperature.

Compared to observations, no stratiform cloud parameterization performed better in simulating all aspects of clouds, temperature, precipitation, and radiation fluxes. There are strong interactions between parameterized stratiform clouds and boundary layer clouds and convection, resulting in changes in low-level cloudiness and precipitation in the simulations.

When the simulations are compared with ISCCP cloudiness and cloud water, and the NCEP/DOE R-2 relative humidity, the cloud amounts simulated by all four cloud schemes depend mostly on relative humidity with less dependency on the model’s cloud water, while the observed cloud amount is more strongly dependent on cloud water than relative humidity, suggesting that cloud parameterizations and the simulation of cloud water require further improvement.
A Case Study of Convective Boundary Layer Development during IHOP_2002: Numerical Simulations Compared to Observations
Authors: Conzemius Robert J. , Fedorovich Evgeni
Published: July 2008

Results are presented from a combined numerical and observational study of the convective boundary layer (CBL) diurnal evolution on a day of the International H2O Project (IHOP_2002) experiment that was marked by the passage of a dryline across part of the Oklahoma and Texas Panhandles. The initial numerical setup was based on observational data obtained from IHOP_2002 measurement platforms and supplementary datasets from surrounding locations. The initial goals of the study were as follows: (i) numerical investigation of the structure and evolution of the relatively shallow and homogeneous CBL east of the dryline by means of large-eddy simulation (LES), (ii) evaluation of LES predictions of the sheared CBL growth against lidar observations of the CBL depth evolution, and (iii) comparison of the simulated turbulence structures with those observed by lidar and vertically pointing radar during the CBL evolution. In the process of meeting these goals, complications associated with comparisons between LES predictions and atmospheric observations of sheared CBLs were encountered, adding an additional purpose to this study, namely, to convey and analyze these issues.

For a period during mid- to late morning, the simulated CBL evolution was found to be in fair agreement with atmospheric lidar and radar observations, and the simulated entrainment dynamics were consistent with those from previous studies. However, CBL depths, determined from lidar data, increased at a faster rate than in the simulations during the afternoon, and the wind direction veered in the simulations more than in the observations. The CBL depth discrepancy can be explained by a dryline solenoidal circulation reported in other studies of the 22 May 2002 case. The discrepancy in winds can be explained by time variation of the large-scale pressure gradient, which was not included in LES.
Analysis and Prediction of a Squall Line Observed during IHOP Using Multiple WSR-88D Observations
Authors: Sun Juanzhen , Zhang Ying
Published: July 2008

This paper presents a case study on the assimilation of observations from multiple Doppler radars of the Next Generation Weather Radar (NEXRAD) network. A squall-line case documented during the International H2O Project (IHOP_2002) is used for the study. Radar radial velocity and reflectivity observations from four NEXRADs are assimilated into a convection-permitting model using a four-dimensional variational data assimilation (4DVAR) scheme. A mesoscale analysis using a supplementary sounding, velocity–azimuth display (VAD) profiles, and surface observations from Meteorological Aerodrome Reports (METAR) are produced and used to provide a background and boundary conditions for the 4DVAR radar data assimilation. Impact of the radar data assimilation is assessed by verifying the skill of the subsequent very short-term (5 h) forecasts.

Assimilation and forecasting experiments are conducted to examine the impact of radar data assimilation on the subsequent precipitation forecasts. It is found that the 4DVAR radar data assimilation significantly reduces the model spinup required in the experiments without radar data assimilation, resulting in significantly improved 5-h forecasts. Additional experiments are conducted to study the sensitivity of the precipitation forecasts with respect to 4DVAR cycling configurations. Results from these experiments suggest that the forecasts with three 4DVAR cycles are improved over those with cold start, but the cycling impact seems to diminish with more cycles. The impact of observations from each of the individual radars is also examined by conducting a set of experiments in which data from each radar are alternately excluded. It is found that the accurate analysis of the environmental wind surrounding the convective cells is important in successfully predicting the squall line.
Dynamical Downscaling of Global Analysis and Simulation over the Northern Hemisphere
Authors: Kanamaru Hideki , Kanamitsu Masao
Published: July 2008

As an extreme demonstration of regional climate model capability, a dynamical downscaling of the NCEP–NCAR reanalysis was successfully performed over the Northern Hemisphere. Its success is due to the use of the scale-selective bias-correction scheme, which maintains the large-scale analysis of the driving global reanalysis in the interior of the domain where lateral boundary forcing has very little control. The downscaled analysis was found to produce reasonable regional details by comparison against 0.5° gridded analysis from the Climatic Research Unit of the University of East Anglia. Comparisons with smaller-area regional downscaling runs in India, Europe, and Japan using the same downscaling system showed that there is no degradation of quality in downscaled climate analysis by expanding the domain from a regional scale to a hemispherical scale.
Impact of NOAA Ground-Based GPS Observations on the Canadian Regional Analysis and Forecast System
Authors: Macpherson S. R. , Deblonde G. , Aparicio J. M. , Casati B.
Published: July 2008

Half-hourly GPS zenith tropospheric delay (ZTD) and collocated surface weather observations of pressure, temperature, and relative humidity are available in near–real time from the NOAA Global Systems Division (GSD) research GPS receiver network. These observations, located primarily over the continental United States, are assimilated in a research version of the Environment Canada (EC) regional (North America) analysis and forecast system. The impact of the assimilation on regional analyses and 0–48-h forecasts is evaluated for two periods: summer 2004 and winter 2004/05. Forecasts are verified against radiosonde, rain gauge, and NOAA GPS network observations.

The impacts of GPS ZTD and collocated surface weather observations for the summer period are generally positive, and include reductions in forecast errors for precipitable water, surface pressure, and geopotential height. It is shown that the ZTD data are primarily responsible for these forecast error reductions. The impact on precipitation forecasts is mixed, but more positive than negative, especially for the central U.S. region and for forecasts of larger precipitation amounts. Assimilation of the collocated surface weather data with ZTD contributes to the positive impact on precipitation forecasts for the central U.S. region. The NOAA GPS network data also have a positive impact on tropical storm system forecasts over the southeast United States, in terms of both storm track and precipitation. Impacts for the winter case are generally smaller because of the lower precipitable water (PW) over North America, but some positive impacts are observed for precipitation forecasts. The greatest regional impacts in the winter case are observed for the southeast U.S. (the Gulf) region where average PW is highest.
Impact of SSM/I Observations Related to Moisture, Clouds, and Precipitation on Global NWP Forecast Skill
Authors: Kelly G. A. , Bauer P. , Geer A. J. , Lopez P. , Thépaut J-N.
Published: July 2008

This paper presents the results from the Observing System Experiments (OSEs) with the current ECMWF data assimilation and modeling system for quantifying the impact on both analysis and forecast quality of Special Sensor Microwave Imager (SSM/I) observations sensitive to moisture and clouds as well as precipitation. SSM/I radiances have been assimilated operationally in clear-sky areas for 8 yr and in cloud- and rain-affected areas since June 2005. This paper examines experiments set up such that clear-sky and rain-affected observations were either added to a baseline with a restricted observing system configuration or withdrawn from the full system. The experiment duration was 10 weeks of which the first 14 days were excluded from the evaluation to allow the system to lose the memory of the initial conditions at day −1.

It is shown that both clear-sky and rain-affected observations account for the bulk correction of moisture in the ECMWF analysis. SSM/I data adds 1 day of forecast skill over the first 48 h when evaluated in addition to a baseline-observing system. In the tropics, the rain-affected data contributes more skill to the moisture forecast than the clear-sky data at 700 hPa and above. In the Northern and Southern Hemispheres, the effect is generally weaker and slightly in favor of clear-sky observations. A similar performance can be seen with respect to the wind vector forecast skill, which reflects the connection between the analysis of moisture and dynamics.
The Influence of Ice Cover on Two Lake-Effect Snow Events over Lake Erie
Authors: Cordeira Jason M. , Laird Neil F.
Published: July 2008

It is generally understood that extensive regions of significant lake ice cover impact lake-effect (LE) snow storms by decreasing the upward heat and moisture fluxes from the lake surface; however, it is only recently that studies have been conducted to more thoroughly examine this relationship. This study provides the first examination of Great Lakes LE snow storms that developed in association with an extensively ice-covered lake. The LE snow events that occurred downwind of Lake Erie on 12–14 February 2003 and 28–31 January 2004 produced maximum snowfall totals of 43 and 64 cm in western New York state, respectively. The presence of widespread ice cover led these snows to be less anticipated than snowfalls from Lake Ontario, which had limited ice cover. For both events, a variety of ice-cover conditions and meso- and synoptic-scale factors (i) helped support LE snow storm development, (ii) lead to the transitions in LE convective type, and (iii) resulted in noteworthy snowfalls near Lake Erie. Thinner ice cover along with favorable fetch directions during the 2004 event likely aided the development of more significant snowband time periods and the resulting greater snowfall. Although Lake Erie had regions with lower ice concentration during the 2003 event, thicker ice cover was present across a greater area of the lake, fetch directions during lake-effect time periods were positioned over higher ice concentration regions, and snowbands had a shorter duration and impacted the same region to a lesser degree than the 2004 case.
A Vortex-Based Perspective of Eastern Pacific Tropical Cyclone Formation
Authors: Davis Christopher , Snyder Chris , Didlake Anthony C.
Published: July 2008

Tropical cyclone formation over the eastern Pacific during 2005 and 2006 was examined using primarily global operational analyses from the National Centers for Environmental Prediction. This paper represents a “vortex view” of genesis, adding to previous work on tropical cyclone formation associated with tropical waves. Between 1 July and 30 September during 2005 and 2006, vortices at 900 hPa were tracked and vortex-following diagnostic quantities were computed. Vortices were more abundant during periods of an enhanced “Hadley” circulation with monsoon westerlies around 10°N in the lower troposphere. This zonally confined Hadley circulation was significantly stronger during the genesis of developing vortices. Developing vortices were stronger at the outset, with a deeper potential vorticity maximum, compared to nondeveloping vortices. This implies that developing disturbances were selected early on by favorable synoptic-scale features.

The characteristic time-mean reversal of the meridional gradient of absolute vorticity in the lower troposphere was found to nearly vanish when the aggregate contribution of strong vortices was removed from the time-mean vorticity. This finding implies that it is difficult to unambiguously attribute development to a preexisting enhancement of vorticity on the synoptic scale. The time-mean enhancement of cyclonic vorticity primarily results from the accumulated effect of vortices. It is suggested that horizontal deformation in the background state helps distinguish developing vortices from nondevelopers, and also biases the latitude of development poleward of the climatological ITCZ axis.
Effects of Transvenous Regional Guanethidine Block in the Treatment of Critical Finger Ischemia
Authors: Stümpflen Andreas , Ahmadi Ali , Atteneder Marcus , Gschwandtner Michael , Hofmann Sabine , Maca Thomas , Schnürer Gerald , Minar Erich , Stümpflen Andreas
Published: July 2008

The objective of this study was to determine the effects of transvenous regional guanethi dine block in the treatment of patients with critical finger ischemia. Twenty-seven patients (17 collagen vascular disease, four thromboangiitis obliterans, three embolism, three atherothrombosis) presenting with ischemic rest pain and/or ulcerations of the fingers received a single block with 5 mg guanethidine injected in 60 mL into the clini cally more affected hand under 30 minutes of arterial arrest. Marked hyperemia was induced in the treated upper limb, increases (p < 0.01) in finger blood flow, finger skin temperature, and laser Doppler flux were higher and longer lasting than in forearm blood flow, persisting for a whole month. Effects in patients with ischemic finger ulcers were less pronounced than in those without, yet statistically significant increases of all evaluated parameters were observed in these patients too. No effects were seen in the contralateral untreated upper limb or in systemic blood pressure. Subjective symptoms (reduction of rest pain, numbness, vasospastic attacks) were improved in 25/27 (92.6%) patients, ischemic rest pain disappeared in 20/27 (74.1%), and complete healing of finger tip ulcerations within 1 month was achieved in 10/12 (83.3%) affected patients. No side effects were observed. This described method combines good clinical efficacy with lack of undesirable side effects and can be repeated easily. Therefore, this technique is recom mended for broader clinical use.
Morphologic and Functional Changes of Left Ventricle in Dialyzed Patients After Treatment with Recombinant Human Erythropoietin (r-HuEPO)
Authors: Jeren-Strujić B. , Raos V. , Jeren T. , Horvatin-Godler S. , Jeren-Strujić B.
Published: July 2008

Dysfunction of the cardiovascular system is a common complication of chronic renal insufficiency. Many factors can cause left ventricular hypertrophy (LVH), and hyperten sion and anemia are among them. They play an important role in the pathogenesis of LVH as well as in the development of cardiac dysfunction. Echocardiography enables early detection of functional macrocirculatory changes as well as adequate measuring of cardiac structures and LV mass. Anemia of end-stage chronic renal insufficiency (ESRD) is only one among its many complications and has complex pathogenesis; one of the primary factors causing anemia is insufficient production of erythropoietin, a leading factor in the production of erythropoiesis. Anemia correction with recombinant human erythropoietin (r-HuEPO) in ESRD has a positive effect on the cardiovascular system. In this study the authors examined the hemodynamic effect of erythropoietin in anemic patients undergoing hemodialysis and observed its positive effect on the cardiovascular system. Twenty-two patients were included in the study (13 men and 9 women) mean age x=39.5 years. All patients were dialyzed three times a week for 4 hours and were all treated, according to protocol, with r-HuEPO for 8 months. Left ventricular mass was measured by the Penn Convention formula. The authors noticed the effectiveness of this therapy through an increase of hemoglobin of 35% and of hematocrit of 34% and a direct effect on the cardiovascular system. Echocardiographic findings showed decrease of LV mass from 391 to 274 mg (30%).

The correction of renal anemia with erythropoietin leads to structural microcircula tory changes and partial morphologic regression of preexistent LVH, which again leads to regression of cardiac dysfunctions and improved hemodynamic effect, physical capacity, and cardiopulmonary status, and ultimately better quality of life for dialyzed patients.