bluuebunny/crossref_metadata_2025 huggingface dataset:
Familial Combined Hyperlipidemia in Mexicans
Authors: Huertas-Vazquez Adriana , Aguilar-Salinas Carlos , Lusis Aldons J. , Cantor Rita M. , Canizales-Quinteros Samuel , Lee Jenny C. , Mariana-Nuñez Lizzette , Riba-Ramirez Roopa-Metha Laura , Jokiaho Anne , Tusie-Luna Teresa , Pajukanta Päivi
Published: June 2005

Objective—

To investigate the largely unknown genetic component of the common lipid disorder, familial combined hyperlipidemia (FCHL) in Mexicans, we analyzed the upstream transcription factor 1 (
USF1
) gene that was recently associated with FCHL and high triglycerides (TG) in Finns. We also analyzed the Mexican FCHL families for 26 microsatellite markers residing in the seven chromosomal regions on 2p25.1, 9p23, 10q11.23, 11q13, 16q24.1, 19q13, and 21q21, previously linked to FCHL in Whites.

Methods and Results—

We genotyped 314 individuals in 24 Mexican families for 13 SNPs spanning an 88-kb region, including
USF1.
The FCHL and TG traits showed significant evidence for association with 3 SNPs, hCV1459766, rs3737787, and rs2073658, and haplotype analyses further supported these findings (probability values of 0.05 to 0.0009 for SNPs and their haplotypes). Of these SNPs, hCV1459766 is located in the F11 receptor (
F11R
) gene, located next to
USF1
, making it difficult to exclude. Importantly, the association was restricted to a considerably smaller region than in the Finns (14 kb versus 46 kb), possibly because of a different underlying linkage disequilibrium structure. In addition, 1 of the 7 regions, 16q24.1, showed suggestive evidence for linkage (a lod score of 2.6) for total cholesterol in Mexicans.

Conclusions—

This study, the first to extensively investigate the genetic component of the common FCHL disorder in Mexicans, provides independent evidence for the role of USF1 in FCHL in an outbred population and links the 16q24.1 region to an FCHL-component trait in Mexicans.
Notch-Dependent Cell Cycle Arrest Is Associated With Downregulation of Minichromosome Maintenance Proteins
Authors: Noseda Michela , Niessen Kyle , McLean Graeme , Chang Linda , Karsan Aly
Published: June 2005

Perturbation of the Notch signaling pathway has been implicated in the pathogenesis of human cardiovascular diseases, and animal models have confirmed the requirement of Notch during cardiovascular development. We recently demonstrated that Notch activation delays S-phase entry and contributes to endothelial contact inhibition. Minichromosome maintenance (MCM) proteins, components of the prereplicative complex (pre-RC), are essential for DNA replication. Here, we report that Notch-mediated cell cycle arrest is associated with downregulation of MCM2 and MCM6 in endothelial cells and human fibroblasts. Downregulation of MCM proteins is also observed on activation of C promoter binding factor (CBF1) and is mediated by inhibition of Rb phosphorylation, as demonstrated using a constitutively active Rb mutant. Although the effects of the Notch pathway are cell-type specific and context-dependent, in cell types where Notch has an antiproliferative effect, downregulation of MCM proteins may be a common mechanism to inhibit DNA replication.
Differences Between Left and Right Ventricular Chamber Geometry Affect Cardiac Vulnerability to Electric Shocks
Authors: Rodríguez Blanca , Li Li , Eason James C. , Efimov Igor R. , Trayanova Natalia A.
Published: June 2005

Although effects of shock strength and waveform on cardiac vulnerability to electric shocks have been extensively documented, the contribution of ventricular anatomy to shock-induced polarization and postshock propagation and thus, to shock outcome, has never been quantified; this is caused by lack of experimental methodology capable of mapping 3-D electrical activity. The goal of this study was to use optical imaging experiments and 3-D bidomain simulations to investigate the role of structural differences between left and right ventricles in vulnerability to electric shocks in rabbit hearts. The ventricles were paced apically, and uniform-field, truncated-exponential, monophasic shocks of reversed polarity were applied over a range of coupling intervals (CIs) in experiment and model. Experiments and simulations revealed that reversing the direction of externally-applied field (RV− or LV− shocks) alters the shape of the vulnerability area (VA), the 2-D grid encompassing episodes of arrhythmia induction. For RV− shocks, VA was nearly rectangular indicating little dependence of postshock arrhythmogenesis on CI. For LV− shocks, the probability of arrhythmia induction was higher for longer than for shorter CIs. The 3-D simulations demonstrated that these effects stem from the fact that reversal of field direction results in relocation of the main postshock excitable area from LV wall (RV− shocks) to septum (LV− shocks). Furthermore, the effect of septal (but not LV) excitable area in postshock propagation was found to strongly depend on preshock state. Knowledge regarding the location of the main postshock excitable area within the 3-D ventricular volume could be important for improving defibrillation efficacy.
Proapoptotic, Antimigratory, Antiproliferative, and Antiangiogenic Effects of Commercial C-Reactive Protein on Various Human Endothelial Cell Types In Vitro
Authors: Liu Chunsheng , Wang Shaohua , Deb Arjun , Nath Karl A. , Katusic Zvonimir S. , McConnell Joseph P. , Caplice Noel M.
Published: June 2005

Recent experimental studies suggest C-reactive protein (CRP) may be a potential mediator of atherosclerosis and its complications. However, there is growing criticism of in vitro CRP studies that use commercial CRP preparations containing biologically active contaminants. The effects of commercial CRP, dialyzed commercial CRP (dCRP) to remove azide, and sodium azide (NaN
3
) alone at equivalent concentrations to the undialyzed preparation were tested at varying concentrations on human umbilical vein endothelial cells (HUVEC), circulating endothelial outgrowth cells (EOC), and endothelial progenitor cells (EPC) in vitro. CRP and NaN
3
alone exhibited equivalent concentration-dependent, proapoptotic effects on HUVEC, EOC, and EPC (
P
<0.01 versus control), whereas dCRP had no such effect. Similarly, CRP and NaN
3
alone caused equivalent concentration-dependent decreases in migration, proliferation, and matrigel tube formation (
P
<0.01 versus control) in EOC and HUVEC, whereas dCRP had absolutely no effect on these biological functions at any of the concentrations used. We conclude that proapoptotic, antiproliferative, antimigratory, and antiangiogenic effects of this commercial CRP preparation on a number of endothelial cell phenotypes in culture may be explained by the presence of sodium azide in this preparation. This study has implications for interpretation of in vitro studies using CRP preparations containing azide at equivalent or higher concentrations.
Endothelin-1, via ET
A
Receptor and Independently of Transforming Growth Factor-β, Increases the Connective Tissue Growth Factor in Vascular Smooth Muscle Cells
Authors: Rodriguez-Vita Juan , Ruiz-Ortega Marta , Rupérez Mónica , Esteban Vanessa , Sanchez-López Elsa , Plaza Juan José , Egido Jesús
Published: June 2005

Endothelin (ET)-1 is a potent vasoconstrictor that participates in cardiovascular diseases. Connective tissue growth factor (CTGF) is a novel fibrotic mediator that is overexpressed in human atherosclerotic lesions, myocardial infarction, and experimental models of hypertension. In vascular smooth muscle cells (VSMCs), CTGF regulates cell proliferation/apoptosis, migration, and extracellular matrix (ECM) accumulation. Our aim was to investigate whether ET-1 could regulate CTGF and to investigate the potential role of ET-1 in vascular fibrosis. In growth-arrested rat VSMCs, ET-1 upregulated CTGF mRNA expression, promoter activity, and protein production. The blockade of CTGF by a CTGF antisense oligonucleotide decreased FN and type I collagen expression in ET-1–treated cells, showing that CTGF participates in ET-1–induced ECM accumulation. The ET
A
, but not ET
B
, antagonist diminished ET-1–induced CTGF expression gene and production. Several intracellular signals elicited by ET-1, via ET
A
receptors, are involved in CTGF synthesis, including activation of RhoA/Rho-kinase and mitogen-activated protein kinase and production of reactive oxygen species. CTGF is a mediator of TGF-β– and angiotensin (Ang) II–induced fibrosis. In VSMCs, ET-1 did not upregulate TGF-β gene or protein. The presence of neutralizing transforming growth factor (TGF)-β antibody did not modify ET-1–induced CTGF production, showing a TGF-β–independent regulation. We have also found an interrelationship between Ang II and ET-1 because the ET
A
antagonist diminished CTGF upregulation caused by Ang II. Collectively, our results show that, in cultured VSMCs, ET-1, independently of TGF-β and through the activation of several intracellular signals via ET
A
receptors, regulates CTGF. This novel finding suggests that CTGF could be a mediator of the profibrotic effects of ET-1 in vascular diseases.
Antiarrhythmic Engineering of Skeletal Myoblasts for Cardiac Transplantation
Authors: Abraham M. Roselle , Henrikson Charles A. , Tung Leslie , Chang Marvin G. , Aon Miguel , Xue Tian , Li Ronald A. , O’ Rourke Brian , Marbán Eduardo
Published: June 2005

Skeletal myoblasts are an attractive cell type for transplantation because they are autologous and resistant to ischemia. However, clinical trials of myoblast transplantation in heart failure have been plagued by ventricular tachyarrhythmias and sudden cardiac death. The pathogenesis of these arrhythmias is poorly understood, but may be related to the fact that skeletal muscle cells, unlike heart cells, are electrically isolated by the absence of gap junctions. Using a novel in vitro model of myoblast transplantation in cardiomyocyte monolayers, we investigated the mechanisms of transplant-associated arrhythmias. Cocultures of human skeletal myoblasts and rat cardiomyocytes resulted in reentrant arrhythmias (spiral waves) that reproduce the features of ventricular tachycardia seen in patients receiving myoblast transplants. These arrhythmias could be terminated by nitrendipine, an
l
-type calcium channel blocker, but not by the Na channel blocker lidocaine. Genetic modification of myoblasts to express the gap junction protein connexin43 decreased arrhythmogenicity in cocultures, suggesting a specific means for increasing the safety (and perhaps the efficacy) of myoblast transplantation in patients.
Heat Shock Protein 27 Is Associated With Freedom From Graft Vasculopathy After Human Cardiac Transplantation
Authors: De Souza A.I. , Wait R. , Mitchell A.G. , Banner N.R. , Dunn M.J. , Rose M.L.
Published: June 2005

Experimental studies have suggested that protective genes protect allografts from cardiac allograft vasculopathy (CAV), the major complication after cardiac transplantation. Here we have sought to confirm this hypothesis using long-term heart transplant recipients. Twenty-two patients that were 9 years or older after transplant were investigated; 11 of these were without angiographic evidence of CAV; 11 had developed early CAV at 1 to 3 years after transplant. To identify proteins that may act as protectors from CAV, a global proteomic approach was used comparing cardiac biopsies from 12 patients taken within the first 2 weeks after transplant and those taken after 9 years from the same patient. Proteins were separated by 2-D gel-electrophoresis, detected by silver staining, and analyzed using Progenesis software. A particular protein spot was found in 4/6 biopsies from patients without CAV, but absent from 5/6 biopsies from those with CAV (
P
=0.24); however, quantitative analysis of spot intensity showed a significant difference (0.061±0.05 versus 0.003±0.01,
P
=0.04). This spot was identified by mass spectrometry and a combination of techniques as a diphosphorylated form of HSP27. Immunohistochemistry of further biopsies not only validated that HSP27 was more abundantly expressed on biopsies without CAV but also showed it to be localized to blood vessels. In contrast, vessels from patients with CAV did not express HSP27 (
P
=0.028×10
−4
). Immunohistochemistry of 12 further early biopsies and nontransplanted heart showed HSP27 to be present in normal blood vessels. These findings suggest that expression of a specific diphosphorylated form of HSP27 is associated with healthy blood vessels; it appears to be lost from vessels of patients with graft vasculopathy.
Spatial and Temporal Patterns of Thunderstorm Events that Produce Cloud-to-Ground Lightning in the Interior Southeastern United States
Authors: Murphy Mark S. , Konrad Charles E.
Published: June 2005

Cloud-to-ground (CG) lightning data are used in this study to trace the daily patterns of thunderstorms in time and space across the topographically diverse southeastern United States. Four reoccurring patterns of thunderstorms (i.e., local, multilocal, regional, and widespread) are identified on the basis of the size of the region of CG lightning as well as the spatial pattern of the flashes within this region. To identify these patterns, hourly maps of CG flashes are produced over five summer seasons (June–August) and used to identify thunderstorm events on all days in which at least one CG lightning is observed. Thunderstorm events are defined by a temporally and spatially clustered hourly pattern of lightning flashes. The spatial pattern of lightning associated with each event is examined during the hour in which the flash density is the highest and is used to classify the event. The geographical and temporal patterns of each thunderstorm type are described. Also, flash densities are calculated at spatial scales ranging from 1- to 100-km radial distance. Over half of the identified thunderstorm events in the study were confined to the local scale and contained relatively few flashes. They were most common early in the morning and in the mountainous portions of the study area. Widespread events, on the other hand, showed a dense coverage of flashes within a given hour over a majority of the area. Although they occurred much less frequently (i.e., once every 8 days across most locales), they were responsible for the highest number of CG lightning flashes in the study region; furthermore, they produced the highest flash densities, both at the local and regional scale. A radar echo classification revealed that these events were not tied to mesoscale convective systems, but rather to the early afternoon development of numerous convective cell clusters and lines across the study area.
A Grid- and Subgrid-Scale Radiation Parameterization of Topographic Effects for Mesoscale Weather Forecast Models
Authors: Müller Mathias D. , Scherer Dieter
Published: June 2005

Complex topography significantly modifies radiation fluxes at the earth’s surface. As spatial resolutions of mesoscale weather forecast models increase, terrain effects on radiation fluxes induced by slope aspect, slope angle, sky view factor, and shadowing also gain importance. A radiation parameterization scheme is hence designed to better represent these topographic influences to improve weather forecasts.

The grid- and subgrid-scale radiation parameterization scheme allows computation of radiation fluxes for each weather forecast model grid cell by considering arbitrarily fine resolved topography without degrading the model’s computational performance. The proposed scheme directly computes mean fluxes for each model grid cell based on flux computations at full spatial resolution of a digital elevation model covering the model domain. Thus the scheme does not require a problematic computation of averaged topographic properties such as aspect angles. Furthermore, the scheme has a nonlocal computation of sky view restriction and shadowing effects.

Case studies with the Nonhydrostatic Mesoscale Model (NMM) at resolutions of 4 and 2 km, respectively, and the parameterization based on a 1-km resolved elevation model, showed that effects of this parameterization are significant and result in better temperature forecasts in complex terrain. Rms and mean error of 2-m temperature forecasts are generally improved by 0.5 to 1 K. At night, the consideration of restricted sky view leads to a temperature increase between 0.5 and 1.5 K along valleys. During clear-sky daytime, this warming is of the same magnitude for grid cells containing slopes exposed to the sun. Under overcast conditions, rms error is reduced by 0.2 to 0.5 K. In wintertime, shadows reduce temperatures in valleys by 0.5 to 3 K during daytime.
Evaluation of Large-Eddy Simulations via Observations of Nocturnal Marine Stratocumulus
Authors: Stevens Bjorn , Moeng Chin-Hoh , Ackerman Andrew S. , Bretherton Christopher S. , Chlond Andreas , de Roode Stephan , Edwards James , Golaz Jean-Christophe , Jiang Hongli , Khairoutdinov Marat , Kirkpatrick Michael P. , Lewellen David C. , Lock Adrian , Müller Frank , Stevens David E. , Whelan Eoin , Zhu Ping
Published: June 2005

Data from the first research flight (RF01) of the second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS-II) field study are used to evaluate the fidelity with which large-eddy simulations (LESs) can represent the turbulent structure of stratocumulus-topped boundary layers. The initial data and forcings for this case placed it in an interesting part of parameter space, near the boundary where cloud-top mixing is thought to render the cloud layer unstable on the one hand, or tending toward a decoupled structure on the other hand. The basis of this evaluation consists of sixteen 4-h simulations from 10 modeling centers over grids whose vertical spacing was 5 m at the cloud-top interface and whose horizontal spacing was 35 m. Extensive sensitivity studies of both the configuration of the case and the numerical setup also enhanced the analysis. Overall it was found that (i) if efforts are made to reduce spurious mixing at cloud top, either by refining the vertical grid or limiting the effects of the subgrid model in this region, then the observed turbulent and thermodynamic structure of the layer can be reproduced with some fidelity; (ii) the base, or native configuration of most simulations greatly overestimated mixing at cloud top, tending toward a decoupled layer in which cloud liquid water path and turbulent intensities were grossly underestimated; (iii) the sensitivity of the simulations to the representation of mixing at cloud top is, to a certain extent, amplified by particulars of this case. Overall the results suggest that the use of LESs to map out the behavior of the stratocumulus-topped boundary layer in this interesting region of parameter space requires a more compelling representation of processes at cloud top. In the absence of significant leaps in the understanding of subgrid-scale (SGS) physics, such a representation can only be achieved by a significant refinement in resolution—a refinement that, while conceivable given existing resources, is probably still beyond the reach of most centers.
Finescale Topography and the MC2 Dynamics Kernel
Authors: Girard Claude , Benoit Robert , Desgagné Michel
Published: June 2005

The Canadian Mesoscale Compressible Community (MC2) model provided daily forecasts across the Alps at 3-km resolution during the Mesoscale Alpine Programme (MAP) field phase of 1999. Among the results of this endeavor, some have had an immediate impact on MC2 itself as it increasingly became evident that the model was spuriously too sensitive to finescale orographic forcing. The model solves the Euler equations of motion using a semi-implicit semi-Lagrangian scheme in an oblique terrain-following coordinate. To improve model behavior, typical approaches were tried at first. These included a generalization of the coordinate transformation to make the terrain influence decay much more quickly with height as well as the introduction of nonisothermal basic states to diminish the amplitude of numerical truncation errors. The concept of piecewise-constant finite elements was invoked to reduce coding arbitrariness. But it was later pointed out that the problem was very specific and due to a numerical inconsistency. The true height of model grid points is fixed and known in height-based coordinates. Nevertheless, it was discovered that for this semi-Lagrangian scheme to be consistent, the departure height is an unknown that must be obtained in the same manner as the other unknowns.
The Cold Front of 15 April 1994 over the Central United States. Part I: Observations
Authors: Demoz B. B. , Starr D. O’C. , Evans K. D. , Lare A. R. , Whiteman D. N. , Schwemmer G. , Ferrare R. A. , Goldsmith J. E. M. , Bisson S. E.
Published: June 2005

Detailed observations of the interactions of a cold front and a dryline over the central United States that led to dramatic undulations in the boundary layer, including an undular bore, are investigated using high-resolution water vapor mixing ratio profiles measured by Raman lidars. The lidar-derived water vapor mixing ratio profiles revealed the complex interaction between a dryline and a cold-frontal system. An elevated, well-mixed, and deep midtropospheric layer, as well as a sharp transition (between 5- and 6-km altitude) to a drier region aloft, was observed. The moisture oscillations due to the undular bore and the mixing of the prefrontal air mass with the cold air at the frontal surface are all well depicted. The enhanced precipitable water vapor and roll clouds, the undulations associated with the bore, the strong vertical circulation and mixing that led to the increase in the depth of the low-level moist layer, and the subsequent lifting of this moist layer by the cold-frontal surface, as well as the feeder flow behind the cold front, are clearly indicated.

A synthesis of the Raman lidar–measured water vapor mixing ratio profiles, satellite, radiometer, tower, and Oklahoma Mesonet data indicated that the undular bore was triggered by the approaching cold front and propagated south-southeastward. The observed and calculated bore speeds were in reasonable agreement. Wave-ducting analysis showed that favorable wave-trapping mechanisms existed; a low-level stable layer capped by an inversion, a well-mixed midtropospheric layer, and wind curvature from a low-level jet were found.
The Development and Structure of an Oceanic Squall-Line System during the South China Sea Monsoon Experiment
Authors: Wang Jian-Jian , Carey Lawrence D.
Published: June 2005

A primary goal of the South China Sea Monsoon Experiment (SCSMEX), a major field campaign of the Tropical Rainfall Measuring Mission (TRMM), is to define the initiation, structure, evolution, and dynamics of precipitation processes associated with the onset of the South China Sea (SCS) summer monsoon. In this study, dual-Doppler and dual-polarimetric radar analysis techniques are used to investigate the development and structure of a squall-line system observed on 24 May 1998. The focus is the linkage between the airflow and the microphysical fields through the system.

The squall-line system, including three distinct lines, persisted from 1200 UTC 24 May to the following day. A detailed study was performed on the structure of the second and most intense line, lasting for over 10 h. Compared to tropical squall lines observed in other regions, this narrow squall-line system had some interesting features including 1) maximum reflectivity as high as 55 dBZ; 2) relatively little stratiform rainfall that preceded instead of trailed the convective line; and 3) a broad vertical velocity maximum in the rear part of the system, rather than a narrow ribbon of vertical velocity maximum near the leading edge.

Polarimetric radar–inferred microphysical (e.g., hydrometeor type, amount, and size) and rainfall properties are placed in the context of the mesoscale morphology and dual-Doppler-derived kinematics for this squall-line system. A comparison is made between results from this study for SCSMEX and the previous studies for the TRMM Large-Scale Biosphere–Atmosphere experiment (LBA). It was found that precipitation over the SCS monsoon region during the summer monsoon onset was similar to the precipitation over the Amazon monsoon region during the westerly regime of the TRMM–LBA, which has previously been found to be closer to typical conditions over tropical oceans. Both of these cases showed lower rain rates and rainwater contents, smaller raindrops, and significantly lower ice water contents between 5 and 8 km than the precipitation over the Amazon during the easterly regime of the TRMM–LBA with more tropical continental characteristics.
Centrifuging of Hydrometeors and Debris in Tornadoes: Radar-Reflectivity Patterns and Wind-Measurement Errors
Authors: Dowell David C. , Alexander Curtis R. , Wurman Joshua M. , Wicker Louis J.
Published: June 2005

High-resolution Doppler radar observations of tornadoes reveal a distinctive tornado-scale signature with the following properties: a reflectivity minimum aloft inside the tornado core (described previously as an “eye”), a high-reflectivity tube aloft that is slightly wider than the tornado core, and a tapering of this high-reflectivity tube near the ground. The results of simple one-dimensional and two-dimensional models demonstrate how these characteristics develop. Important processes in the models include centrifugal ejection of hydrometeors and/or debris by the rotating flow and recycling of some objects by the near-surface inflow and updraft.

Doppler radars sample the motion of objects within the tornado rather than the actual airflow. Since objects move at different speeds and along different trajectories than the air, error is introduced into kinematic analyses of tornadoes based on radar observations. In a steady, axisymmetric tornado, objects move outward relative to the air and move more slowly than the air in the tangential direction; in addition, the vertical air-relative speed of an object is less than it is in still air. The differences between air motion and object motion are greater for objects with greater characteristic fall speeds (i.e., larger, denser objects) and can have magnitudes of tens of meters per second. Estimates of these differences for specified object and tornado characteristics can be obtained from an approximation of the one-dimensional model.

Doppler On Wheels observations of the 30 May 1998 Spencer, South Dakota, tornado demonstrate how the apparent tornado structure can change when the radar-scatterer type changes. When the Spencer tornado entered the town and started lofting debris, changes occurred in the Doppler velocity and reflectivity fields that are consistent with an increase in mean scatterer size.
The Extratropical Transition of Tropical Cyclone Lili (1996) and Its Crucial Contribution to a Moderate Extratropical Development
Authors: Agustí-Panareda Anna , Gray Suzanne L. , Craig George C. , Thorncroft Chris
Published: June 2005

The transition that a tropical cyclone experiences as it moves into the extratropical environment (known as extratropical transition) can result in the decay or intensification of a baroclinic cyclone. The extratropical transition (ET) of Tropical Cyclone Lili (1996) in the North Atlantic resulted in a moderate extratropical development of a baroclinic cyclone. The impact of Lili in the extratropical development that occurred during its ET is investigated. Numerical experiments are performed using potential vorticity inversion and the Met Office Unified Model to forecast the extratropical development with and without the tropical cyclone in the initial conditions. In contrast with other case studies in the literature, Lili is shown to play a crucial role during its ET in the development of a baroclinic cyclone that occurred in the same region. A hypothesis of the possible scenarios of ET is presented that links the case-to-case variability of ET case studies in the literature with a classification of the life cycles of baroclinic cyclones.
Radar Observations of the Diurnally Forced Offshore Convective Lines along the Southeastern Coast of Taiwan
Authors: Yu Cheng-Ku , Jou Ben Jong-Dao
Published: June 2005

This study documents offshore convective lines along the southeastern coast of Taiwan, a frequent but poorly understood mesoscale phenomenon that influences coastal weather during the Taiwan mei-yu season. Doppler radar and surface observations were gathered from a specially chosen period (11–15 May 1998) when the offshore convective lines were active off the southeastern coast of Taiwan. These observations were used to show the basic character, structure, and possible formative processes of offshore convective lines. The synoptic environment accompanying these events was found to be relatively undisturbed and featured uniformly prevailing southerly/south-southeasterly winds in the boundary layer with southwesterlies/westerlies aloft. Examination of radar data during the study period indicates that the lines generally occurred ∼10–30 km offshore and were characterized by an elongated narrow zone (∼5–10 km wide) of heavy precipitation. The lines were oriented roughly parallel to the coastline and generally did not move significantly. The intensity of the radar reflectivity associated with the lines exhibited a marked diurnal variation and was closely related to the coastal offshore flow developing at night.

Detailed analyses of an event on 14–15 May 1998 further show the important physical link between the offshore flow and the development of the line. The offshore line was found to be located near and immediately ahead of the seaward extent of the offshore flow. Particularly, a very narrow zone (∼2 km) of low-level heavy precipitation (40–45 dBZ) coincided with regions of strong updrafts and convergence, where the prevailing southerly onshore flow encountered the cool offshore flow nearshore. This offshore flow–induced convergence, given a stable thermodynamic condition in the lowest ∼1 km in the inflow region, was a crucial low-level forcing that provided lifting to trigger moist deep convection in this case. The line’s precipitation tilt eastward was confined primarily to the warmer inflow side rather than feeding the offshore flow to the west of the line. No consistent upshear tilt of updrafts throughout the storm layer was observed, which is consistent with the presence of a strong westerly shear in the line’s environment. Both of these observations explain a relatively strong (weak) modification of low-level onshore (offshore) flow by precipitation. Additionally, a combination of surface and Doppler radar observations indicates that the leading edge of the offshore flow moved seaward very slowly at 0.7 m s−1 and possessed a frontal character with notable discontinuities in near-surface wind and temperature (instead of pressure and dewpoint temperature).
Southerly Surges on Submonthly Time Scales over the Eastern Indian Ocean during the Southern Hemisphere Winter
Authors: Fukutomi Yoshiki , Yasunari Tetsuzo
Published: June 2005

Meridional wind surges from the extratropics into the Tropics strongly regulate tropical convective activity. This paper confirms that extratropical forcing manifested as a meridional surge does modulate the tropical atmosphere over the eastern Indian Ocean, and it describes the tropical–extratropical connection in the region.

Surges in the lower atmosphere on submonthly (6–25 days) time scales over the eastern Indian Ocean were examined in tandem with associated tropical convection and large-scale atmospheric fields during the Southern Hemisphere (SH) winter (June–August). Data used in this study are NCEP-2 reanalyses and daily NOAA/Climate Diagnostics Center (CDC) outgoing longwave radiation (OLR) data for 23 yr, from 1979 to 2001. A low-level surge index was calculated using the 850-hPa meridional wind component (υ) averaged over a region where sub–monthly scale υ variance shows a local maximum (17.5°–2.5°S, 87.5°–97.5°E). The surge index defines 62 different surge events. Composites of various components were generated based on the index to define relationships between surge events and large-scale fields.

Low-level southerly surges over the eastern Indian Ocean originate from midlatitude Rossby waves with strong baroclinic development in the entrance region of a subtropical jet core off Australia’s west coast. Strengthened low-level wind surges cause cross-equatorial flow stretching from the subtropical eastern Indian Ocean to the southern Bay of Bengal. Surges are accompanied by the advection of cold, dry air from midlatitudes into the Tropics. A cold and dry front develops at the leading surge edge during the surge period. Two to four days later, as the surge peaks, negative OLR anomalies develop near the key region. The OLR anomalies indicate a local blow up of convection over the tropical eastern Indian Ocean. Convection reflects increased instability in the surge region, which is caused by low-level dry air advection and near-surface moistening that is forced by enhanced sea surface evaporation associated with the surge. The southerly surge on submonthly time scales is an important bridge linking the Tropics and midlatitudes over the Indian Ocean.
A Spatial Two-Dimensional Discrete Filter for Limited-Area-Model Evaluation Purposes
Authors: Feser Frauke , von Storch Hans
Published: June 2005

A two-dimensional discrete spatial filter was developed. It serves as a means to classify meteorological fields on a limited-area grid according to their spatial dimensions by filtering certain wavenumber ranges. Thereby it performs an isotropic spatial-scale separation of the atmospheric fields. A general algorithm was developed, which allows the construction of a filter that closely approximates a specific isotropic response function. The filter is simple in the construction and easy to apply while giving reasonable results. The method allows for considerable flexibility in choosing this specific response. This way, low-, band-, and high-pass filters are obtained. Examples show an effective scale separation of atmospheric fields on limited-area grids that can be used for process studies, model evaluation, or comparisons.
Atlantic Hurricane Season of 2003
Authors: Lawrence Miles B. , Avila Lixion A. , Beven John L. , Franklin James L. , Pasch Richard J. , Stewart Stacy R.
Published: June 2005

The 2003 Atlantic hurricane season is described. The season was very active, with 16 tropical storms, 7 of which became hurricanes. There were 49 deaths directly attributed to this year’s tropical cyclones.
Linearization of a Simple Moist Convection Scheme for Large-Scale NWP Models
Authors: Mahfouf Jean-François
Published: June 2005

A simple Kuo-type convection scheme with an improved closure based on moist enthalpy accession (Kuo symmetric) has been linearized for the tangent-linear (TL) and adjoint (AD) versions of the Global Environmental Multiscale (GEM) model. The nonlinear scheme exhibits a reasonable behavior in terms of heating and moistening rates when evaluated in stand-alone mode over a set of deep convective profiles. A preliminary evaluation of a straightforward linearization in the global TL model has revealed the existence of noise that leads to an unacceptable solution after 12 h of integration. By neglecting several terms in the linearization (detrainment rate and cloud properties), the temporal evolution of humidity analysis increments is improved by including this simplified linearized convection scheme in the TL model. The behavior of the linearized scheme has also been compared favorably to the linearized version of the European Centre for Medium-Range Weather Forecasts (ECMWF) mass-flux convection scheme. When examining the validity of the TL approximation for surface precipitation, it appears that linearization errors are large for both stratiform and convective rainfall (rms errors are about twice the mean absolute perturbed precipitation). These errors are not reduced when considering accumulated rain rates instead of instantaneous quantities. However, the occurrence of “on–off” processes is reduced by a temporal integration of rain. This could make the variational assimilation of accumulated precipitation rates easier. Finally, errors coming from internal nonlinearities are slightly larger than those produced by discontinuities. This confirms the interest for improving the linearity of nonlinear convection schemes for applications in variational contexts.
Moist Dynamics and Orographic Precipitation in Northern and Central California during the New Year’s Flood of 1997
Authors: Galewsky Joseph , Sobel Adam
Published: June 2005

The dynamics of moist orographic flows during the January 1997 floods in northern and central California are investigated using numerical simulations computed with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5). Early in the event (31 December 1996–1 January 1997), the low-level winds offshore of California’s central coast were blocked by the topography of the Santa Lucia Range, and the low-level winds in the Central Valley were blocked by the topography of the central Sierra Nevada Range. In contrast, moisture-laden winds along the northern Coast Ranges and the northern Sierra Nevada flowed over topographic barriers. As the core of humid air migrated to the south over 24 h, the low-level barrier jets weakened as the atmospheric stability decreased, bringing heavy rainfall to the central and southern Sierra Nevada at the end of the event. The heavy precipitation during this event was largely controlled by the interaction of the flow with topography, with little contribution from non–topographically forced dynamical uplift. Latent heating was essential for lowering the effective stability of the flow and allowing the winds to flow over mountainous terrain, particularly in the northern Coast Ranges, and for enhancing the low-level jet and associated moisture transport. The horizontal distribution of static stability played a key role in the event by setting up a complex combination of flow-over and flow-around regimes that enhanced uplift in the northern Sierra Nevada during the period of heaviest rainfall.
Relative Humidity over the West Florida Continental Shelf
Authors: Virmani J. I. , Weisberg R. H.
Published: June 2005

Observed relative humidity variations on the coastal ocean of the West Florida Continental Shelf (WFS) are examined over the 5-yr period 1998–2003. Despite considerable daily variability within seasons, the monthly mean values are nearly constant at about 75%. Summertime specific humidity is twice that during winter, so high air temperatures are responsible for the low summer monthly mean relative humidities. Winter has the greatest relative humidity variability; values range from less than 50% to over 100% as extratropical fronts move over the WFS. Saturation (and fog) occurs as warm moist air passes over colder water. Two different sensors, mounted on multiple moorings, were used to make these observations. Monthly mean values from the Rotronics MP-100F are higher than the Hygrometrix 1020SHT. In addition to sensor differences, a contributing cause to this offset appears to be the locations chosen for sensor deployment. NCEP reanalysis climatology over the WFS and land-based coastal data both show an annual cycle in monthly mean relative humidity, with higher values in summer, suggesting that the reanalysis field is influenced by land. Air–sea fluxes over the WFS are sensitive to small spatial variability in the coastal ocean and atmosphere. The large grid spacing of the NCEP reanalysis does not capture this variability. The lack of coastal ocean data for assimilation biases the NCEP reanalysis fields toward land-based measurements. Increased spatial coverage via evolving Coastal Ocean Observing Systems should remedy this problem by providing required information for describing and understanding the complicated ocean–atmosphere interactions that occur on continental shelves.
Alignment Error Models and Ensemble-Based Data Assimilation
Authors: Lawson W. Gregory , Hansen James A.
Published: June 2005

The concept of alternative error models is suggested as a means to redefine estimation problems with non-Gaussian additive errors so that familiar and near-optimal Gaussian-based methods may still be applied successfully. The specific example of a mixed error model including both alignment errors and additive errors is examined. Using the specific form of a soliton, an analytical solution to the Korteweg–de Vries equation, the total (additive) errors of states following the mixed error model are demonstrably non-Gaussian for large enough alignment errors, and an ensemble of such states is handled poorly by a traditional ensemble Kalman filter, even if position observations are included. Consideration of the mixed error model itself naturally suggests a two-step approach to state estimation where the alignment errors are corrected first, followed by application of an estimation scheme to the remaining additive errors, the first step aimed at removing most of the non-Gaussianity so the second step can proceed successfully. Taking an ensemble approach for the soliton states in a perfect-model scenario, this two-step approach shows a great improvement over traditional methods in a wide range of observational densities, observing frequencies, and observational accuracies. In cases where the two-step approach is not successful, it is often attributable to the first step not having sufficiently removed the non-Gaussianity, indicating the problem strictly requires an estimation scheme that does not make Gaussian assumptions. However, in these cases a convenient approximation to the two-step approach is available, which trades obtaining a minimum variance estimate ensemble mean for more physically sound updates of the individual ensemble members.
Maximum Likelihood Ensemble Filter: Theoretical Aspects
Authors: Zupanski Milija
Published: June 2005

A new ensemble-based data assimilation method, named the maximum likelihood ensemble filter (MLEF), is presented. The analysis solution maximizes the likelihood of the posterior probability distribution, obtained by minimization of a cost function that depends on a general nonlinear observation operator. The MLEF belongs to the class of deterministic ensemble filters, since no perturbed observations are employed. As in variational and ensemble data assimilation methods, the cost function is derived using a Gaussian probability density function framework. Like other ensemble data assimilation algorithms, the MLEF produces an estimate of the analysis uncertainty (e.g., analysis error covariance). In addition to the common use of ensembles in calculation of the forecast error covariance, the ensembles in MLEF are exploited to efficiently calculate the Hessian preconditioning and the gradient of the cost function. A sufficient number of iterative minimization steps is 2–3, because of superior Hessian preconditioning. The MLEF method is well suited for use with highly nonlinear observation operators, for a small additional computational cost of minimization. The consistent treatment of nonlinear observation operators through optimization is an advantage of the MLEF over other ensemble data assimilation algorithms. The cost of MLEF is comparable to the cost of existing ensemble Kalman filter algorithms. The method is directly applicable to most complex forecast models and observation operators. In this paper, the MLEF method is applied to data assimilation with the one-dimensional Korteweg–de Vries–Burgers equation. The tested observation operator is quadratic, in order to make the assimilation problem more challenging. The results illustrate the stability of the MLEF performance, as well as the benefit of the cost function minimization. The improvement is noted in terms of the rms error, as well as the analysis error covariance. The statistics of innovation vectors (observation minus forecast) also indicate a stable performance of the MLEF algorithm. Additional experiments suggest the amplified benefit of targeted observations in ensemble data assimilation.
MODIS-Derived Boundary Conditions for a Mesoscale Climate Model: Application to Irrigated Agriculture in the Euphrates Basin
Authors: Zaitchik Benjamin F. , Evans Jason , Smith Ronald B.
Published: June 2005

In arid and semiarid parts of the world, evaporation from irrigated fields may significantly influence humidity, near-surface winds, and precipitation. Using Moderate Resolution Imaging Spectroradiometer (MODIS) Terra imagery from summer and autumn 2000 the authors attempt to improve the realism of a regional climate model (the fifth-generation Pennsylvania State University–NCAR Mesoscale Model) with respect to irrigated agriculture. MODIS data were used to estimate spatially distributed vegetation fraction and to identify areas of irrigated land use. Additionally, a novel surface flux routine designed to simulate traditional flood irrigation was implemented. Together these modifications significantly improved model predictions of water flux and the surface energy balance when judged against independent weather station data and known crop requirements. Model estimates of watershed-level water consumption were more than doubled relative to simulations that did not incorporate MODIS data, and there were small but systematic differences in predicted temperature and humidity near the surface. The modified version of the mesoscale model also predicts the existence of heat-driven circulations around large irrigated features, and these circulations are similar in structure and magnitude to those predicted by linear theory. Based on these results, it was found that accurate representation of irrigated agriculture is a prerequisite to any study of the impact of land-use change on climate or on water resources.
Traveling to Violence: The Case for a Mobility-Based Spatial Typology of Homicide
Authors: Tita George , Griffiths Elizabeth
Published: June 2005

According to routine activities theory, crime is the result of an intersection between victims and offenders in both time and space. We introduce a spatial typology that identifies five combinations of victim and offender mobility to homicide incident locations: internal, predatory, intrusion, offense mobility, and total mobility types. The authors’ argue that the joint mobility pattern of the victim and offender is the mechanism underlying routine activities theory, and made explicit by the spatial typology. Using information on the 420 homicides in Pittsburgh, Pennsylvania, between 1987 and 1995, we demonstrate that the majority of homicides involve at least some mobility on the part of victims and/or offenders. Our results also indicate that mobility to homicide incident locations is most associated with event characteristics such as motive, rather than with characteristics of the participants. With most offenders committing the homicide outside of their own neighborhood, levels of lethal violence in a community are influenced more by the interaction among nonlocal participants than by the violent actions of local residents.
Examining the Effectiveness of Boot Camps: A Randomized Experiment with a Long-Term Follow Up
Authors: Bottcher Jean , Ezell Michael E.
Published: June 2005

The boot camp model became a correctional panacea for juvenile offenders during the early 1990s, promising the best of both worlds—less recidivism and lower operating costs. Although there have been numerous studies of boot camp programs since that time, most have relied on nonrandomized comparison groups. The California Youth Authority’s (CYA’s) experimental study of its juvenile boot camp and intensive parole program (called LEAD)—versus standard custody and parole—was an important exception, but its legislatively mandated in-house evaluation was prepared before complete outcome data were available. The present study capitalizes on full and relatively long-term follow-up arrest data for the LEAD evaluation provided by the California Department of Justice in August 2002. Using both survival models and negative binomial regression models, the results indicate that there were no significant differences between groups in terms of time to first arrest or average arrest frequency.