bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Plasma Oxidized Low-Density Lipoprotein Removal on Atherosclerosis
Authors: Ishigaki Yasushi , Katagiri Hideki , Gao Junhong , Yamada Tetsuya , Imai Junta , Uno Kenji , Hasegawa Yutaka , Kaneko Keizo , Ogihara Takehide , Ishihara Hisamitsu , Sato Yuko , Takikawa Kenji , Nishimichi Norihisa , Matsuda Haruo , Sawamura Tatsuya , Oka Yoshitomo
Published: June 2008

Background—

Several clinical studies of statin therapy have demonstrated that lowering low-density lipoprotein (LDL) cholesterol prevents atherosclerotic progression and decreases cardiovascular mortality. In addition, oxidized LDL (oxLDL) is suggested to play roles in the formation and progression of atherosclerosis. However, whether lowering oxLDL alone, rather than total LDL, affects atherogenesis remains unclear.

Methods and Results—

To clarify the atherogenic impact of oxLDL, lectin-like oxLDL receptor 1 (LOX-1), an oxLDL receptor, was expressed ectopically in the liver with adenovirus administration in apolipoprotein E–deficient mice at 46 weeks of age. Hepatic LOX-1 expression enhanced hepatic oxLDL uptake, indicating functional expression of LOX-1 in the liver. Although plasma total cholesterol, triglyceride, and LDL cholesterol levels were unaffected, plasma oxLDL was markedly and transiently decreased in LOX-1 mice. In controls, atherosclerotic lesions, detected by Oil Red O staining, were markedly increased (by 38%) during the 4-week period after adenoviral administration. In contrast, atherosclerotic progression was almost completely inhibited by hepatic LOX-1 expression. In addition, plasma monocyte chemotactic protein-1 and lipid peroxide levels were decreased, whereas adiponectin was increased, suggesting decreased systemic oxidative stress. Thus, LOX1 expressed in the livers of apolipoprotein E–deficient mice transiently removes oxLDL from circulating blood and possibly decreases systemic oxidative stress, resulting in complete prevention of atherosclerotic progression despite the persistence of severe LDL hypercholesterolemia and hypertriglyceridemia.

Conclusions—

OxLDL has a major atherogenic impact, and oxLDL removal is a promising therapeutic strategy against atherosclerosis.
Intracoronary Compared With Intravenous Bolus Abciximab Application in Patients With ST-Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention
Authors: Thiele Holger , Schindler Kathrin , Friedenberger Josef , Eitel Ingo , Fürnau Georg , Grebe Eigk , Erbs Sandra , Linke Axel , Möbius-Winkler Sven , Kivelitz Dietmar , Schuler Gerhard
Published: June 2008

Background—

Abciximab reduces major adverse cardiac events in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention (PCI). Intracoronary abciximab bolus application results in high local drug concentrations and may be more effective than a standard intravenous bolus.

Methods and Results—

Patients undergoing primary PCI were randomized to either intracoronary (n=77) or intravenous (n=77) bolus abciximab administration with subsequent 12-hour intravenous infusion. The primary end point was infarct size and extent of microvascular obstruction as assessed by delayed enhancement magnetic resonance. Secondary end points were ST-segment resolution at 90 minutes, Thrombolysis in Myocardial Infarction flow and perfusion grades after PCI, and the occurrence of major adverse cardiac events within 30 days. The median infarct size was 15.1% (interquartile range, 6.1% to 25.2%) in the intracoronary versus 23.4% (interquartile range, 13.6% to 33.2%) in the intravenous group (
P
=0.01). Similarly, the extent of microvascular obstruction was significantly smaller in intracoronary compared with intravenous abciximab patients (
P
=0.01). Myocardial perfusion measured as early ST-segment resolution was significantly improved in intracoronary patients with an absolute ST-segment resolution of 77.8% (interquartile range, 66.7% to 100.0%) versus 70.0% (interquartile range, 45.2% to 83.5%;
P
=0.006). The Thrombolysis in Myocardial Infarction flow after PCI was not different between treatment groups (
P
=0.51), but there was a trend toward an improved perfusion grade (
P
=0.09). There also was a trend toward a lower major adverse cardiac event rate after intracoronary versus intravenous abciximab application (5.2% versus 15.6%;
P
=0.06; relative risk, 0.33; 95% CI, 0.09 to 1.05).

Conclusions—

Intracoronary bolus administration of abciximab in primary PCI is superior to standard intravenous treatment with respect to infarct size, extent of microvascular obstruction, and perfusion.
Gender and Outcome in Adult Congenital Heart Disease
Authors: Verheugt Carianne L. , Uiterwaal Cuno S.P.M. , van der Velde Enno T. , Meijboom Folkert J. , Pieper Petronella G. , Vliegen Hubert W. , van Dijk Arie P.J. , Bouma Berto J. , Grobbee Diederick E. , Mulder Barbara J.M.
Published: June 2008

Background—

Gender differences in prognosis have frequently been reported in cardiovascular disease but less so in congenital heart disease. We investigated whether gender is associated with outcome in adult patients with congenital heart disease.

Methods and Results—

From the CONgenital CORvitia (CONCOR) national registry for adults with congenital heart disease, 7414 patients were identified. All outcomes before entry into the registry and during subsequent follow-up were recorded, and differences between men and women were analyzed with the underlying congenital heart defect taken into account. Median age at the end of follow-up was 35 years (range, 17 to 91 years); 49.8% were female. No gender difference in mortality was found. Women had a 33% higher risk of pulmonary hypertension (odds ratio [OR]=1.33; 95% CI, 1.07 to 1.65;
P
=0.01), a 33% lower risk of aortic outcomes (OR=0.67; 95% CI, 0.50 to 0.90;
P
=0.007), a 47% lower risk of endocarditis (OR=0.53; 95% CI, 0.40 to 0.70;
P
<0.001), and a 55% lower risk of an implantable cardioverter-defibrillator (OR=0.45; 95% CI, 0.26 to 0.80;
P
=0.006). Furthermore, the risk of arrhythmias appeared to be lower in women (OR=0.88; 95% CI, 0.77 to 1.02;
P
=0.08).

Conclusions—

The risk of several major cardiac outcomes in adult patients with congenital heart disease appears to vary by gender.
Renal and Hormonal Responses to Direct Renin Inhibition With Aliskiren in Healthy Humans
Authors: Fisher Naomi D.L. , Jan Danser A.H. , Nussberger J. , Dole William P. , Hollenberg Norman K.
Published: June 2008

Background—

Pharmacological interruption of the renin-angiotensin system focuses on optimization of blockade. As a measure of intrarenal renin activity, we have examined renal plasma flow (RPF) responses in a standardized protocol. Compared with responses with angiotensin-converting enzyme inhibition (rise in RPF ≈95 mL · min
−1
· 1.73 m
−2
), greater renal vasodilation with angiotensin receptor blockers (≈145 mL · min
−1
· 1.73 m
−2
) suggested more effective blockade. We predicted that blockade with the direct oral renin inhibitor aliskiren would produce renal vascular responses exceeding those induced by angiotensin-converting enzyme inhibitors and angiotensin receptor blockers.

Methods and Results—

Twenty healthy normotensive subjects were studied on a low-sodium (10 mmol/d) diet, receiving separate escalating doses of aliskiren. Six additional subjects received captopril 25 mg as a low-sodium comparison and also received aliskiren on a high-sodium (200 mmol/d) diet. RPF was measured by clearance of para-aminohippurate. Aliskiren induced a remarkable dose-related renal vasodilation in low-sodium balance. The RPF response was maximal at the 600-mg dose (197±27 mL · min
−1
· 1.73 m
−2
) and exceeded responses to captopril (92±20 mL · min
−1
· 1.73 m
−2
;
P
<0.01). Furthermore, significant residual vasodilation was observed 48 hours after each dose (
P
<0.01). The RPF response on a high-sodium diet was also higher than expected (47±17 mL · min
−1
· 1.73 m
−2
). Plasma renin activity and angiotensin levels were reduced in a dose-related manner. As another functional index of the effect of aliskiren, we found significant natriuresis on both diets.

Conclusions—

Renal vasodilation in healthy people with the potent renin inhibitor aliskiren exceeded responses seen previously with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. The effects were longer lasting and were associated with significant natriuresis. These results indicate that aliskiren may provide more complete and thus more effective blockade of the renin-angiotensin system.
Alternative Splicing of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Is Associated With Plasma Low-Density Lipoprotein Cholesterol Response to Simvastatin
Authors: Medina Marisa Wong , Gao Feng , Ruan Weiming , Rotter Jerome I. , Krauss Ronald M.
Published: June 2008

Background—

HMGCR
(3-Hydroxy-3-methylglutaryl coenzyme A reductase), the direct target of statin inhibition, undergoes alternative splicing of exon 13, which encodes part of the statin-binding domain of the enzyme. We hypothesized that
HMGCR
alternative splicing might be related to the interindividual variation in plasma low-density lipoprotein cholesterol response to statin treatment.

Methods and Results—

We measured mRNA expression of both the full-length and the alternatively spliced
HMGCR
transcript lacking exon 13 (
HMGCRv_1
) in 170 simvastatin-incubated immortalized lymphocyte cell lines derived from participants in the Cholesterol and Pharmacogenetics (CAP) study who were treated with simvastatin 40 mg/d for 6 weeks. Greater upregulation of
HMGCRv_1
in vitro was significantly correlated (
P
≤0.0001) with smaller in vivo reductions of plasma total cholesterol, low-density lipoprotein cholesterol, apoprotein B, and triglycerides and explained 6% to 15% of the variation in their response to treatment. In contrast, no significant relationship was found between expression of the full-length
HMGCR
transcript and in vivo response. By siRNA knockdown of the full-length transcript, we found that HMGCR enzyme activity measured in cells enriched in
HMGCRv_1
was relatively resistant to statin inhibition, consistent with the association of increased alternative splicing with reduced statin response in the CAP study. In addition, we found that a common
HMGCR
single-nucleotide polymorphism (rs3846662) located within intron 13 was associated with variation in the proportion of
HMGCR
mRNA that is alternatively spliced.

Conclusions—

Variation in the production of an HMGCR isoform with reduced statin sensitivity is a determinant of interindividual differences in low-density lipoprotein cholesterol, apolipoprotein B, and triglyceride response to statin treatment.
History of Hypertension and Eplerenone in Patients With Acute Myocardial Infarction Complicated by Heart Failure
Authors: Pitt Bertram , Ahmed Ali , Love Thomas E. , Krum Henry , Nicolau Jose , Cardoso José S. , Parkhomenko Alexander , Aschermann Michael , Corbalán Ramon , Solomon Henry , Shi Harry , Zannad Faiez
Published: June 2008

In the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (n=6632), eplerenone-associated reduction in all-cause mortality was significantly greater in those with a history of hypertension (Hx-HTN). There were 4007 patients with Hx-HTN (eplerenone: n=1983) and 2625 patients without Hx-HTN (eplerenone: n=1336). Propensity scores for eplerenone use, separately calculated for patients with and without Hx-HTN, were used to assemble matched cohorts of 1838 and 1176 pairs of patients. In patients with Hx-HTN, all-cause mortality occurred in 18% of patients treated with placebo (rate, 1430/10 000 person-years) and 14% of patients treated with eplerenone (rate, 1058/10 000 person-years) during 2350 and 2457 years of follow-up, respectively (hazard ratio [HR]: 0.71; 95% CI: 0.59 to 0.85;
P
<0.0001). Composite end point of cardiovascular hospitalization or cardiovascular mortality occurred in 33% of placebo-treated patients (3029/10 000 person-years) and 28% of eplerenone-treated patients (2438/10 000 person-years) with Hx-HTN (HR: 0.82; 95% CI: 0.72 to 0.94;
P
=0.003). In patients without Hx-HTN, eplerenone reduced heart failure hospitalization (HR: 73; 95% CI: 0.55 to 0.97;
P
=0.028) but had no effect on mortality (HR: 0.91; 95% CI: 0.72 to 1.15;
P
=0.435) or on the composite end point (HR: 0.91; 95% CI: 0.76 to 1.10;
P
=0.331). Eplerenone should, therefore, be prescribed to all of the post–acute myocardial infarction patients with reduced left ventricular ejection fraction and heart failure regardless of Hx-HTN.
Aortic Stiffness in Untreated Adult Patients With Human Immunodeficiency Virus Infection
Authors: Schillaci Giuseppe , De Socio Giuseppe V.L. , Pucci Giacomo , Mannarino Massimo R. , Helou Johny , Pirro Matteo , Mannarino Elmo
Published: June 2008

HIV infection is associated with chronic immune activation, subclinical inflammation, and an atherogenic metabolic profile. It remains controversial whether HIV infection is a risk factor for accelerated arteriosclerosis independent from the effects of antiretroviral drugs. We investigated whether aortic stiffness, an early marker of arteriosclerosis, is increased in HIV patients who were not under antiretroviral treatment. In 39 untreated HIV-infected patients and 78 individually matched age-, sex-, and blood pressure–matched HIV-uninfected control subjects, we determined aortic pulse wave velocity (PWV), a direct noninvasive measure of aortic stiffness, by tonometric method. Subjects with overt cardiovascular disease or major cardiovascular risk factors were excluded from the study. Prevalence of the metabolic syndrome was higher in HIV patients (18% versus 5%;
P
=0.025). HIV patients had a higher aortic PWV (7.5±1.4 versus 6.7±1.1 m · s
−1
;
P
=0.001) than control subjects. Age, mean arterial pressure as a measure of distending pressure, and HIV infection (all
P
<0.05) independently predicted aortic PWV when a consistent number of cardiovascular risk factors was simultaneously controlled for. Among HIV-infected subjects, serum γ-glutamyl transpeptidase concentration (β=0.46;
P
=0.003) and mean arterial pressure (β=0.32;
P
=0.03) were independent determinants of aortic PWV. In conclusion, aortic stiffness is increased in HIV-infected individuals who have never received antiretroviral therapy. PWV increases with increasing serum γ-glutamyl transpeptidase concentration. Our data support the hypothesis that HIV infection is a risk factor for arteriosclerosis.
Exponential Size Distributions for Snow
Authors: Heymsfield Andrew J. , Field Paul , Bansemer Aaron
Published: June 2008

Using airborne data from several recent field projects, the authors have taken another look at the properties of exponential ice particle size distributions (PSDs) when the PSDs are broad. Two primary questions are addressed: for what ranges of ice water content (IWC) and equivalent radar reflectivity (Ze) do exponentials produce accurate estimates of these higher moments of the PSD, and why is there a lower limit to the value to the slope of exponential fits to PSD, λ, as has been found from airborne measurements?

Earlier studies at temperatures primarily above −10°C have found that λ measured in snow during spiral descents through deep ice cloud layers decreases to about 9 cm−1 and then remains there. Several physical processes have been advanced to explain these observations. If reliable, the data could be used to improve retrieval of ice cloud properties through remote sensing and for cloud model representations of ice cloud microphysical properties.

For data acquired from 2D probes, recent evidence indicates shattering of large ice particles ahead of, but attributable to, the probe’s sensing area, generating small crystals that the probe then senses. Shattered artifacts have been objectively removed from the data. Comparisons of size distributions before and after removal of suspected shattered particles suggest that the reported minimum may have been due to shattering and/or other instrument errors.

The revised PSDs indicate that for λ < 40 cm−1, 0.1 g m−1 < IWC, and 5 dB < Ze, moments two (IWC) through four (Ze) of the PSD are dominated by particles larger than a few hundred microns. Analytical representations with more variables than exponentials (e.g., gamma PSD) are not required to accurately derive these moments from the PSD. In these situations, the intercept parameter of the exponential PSD, N0 ≈ 1 cm−4, is 5 to 30 times larger than assumed earlier.
Entrainment in Cumulus Clouds: What Resolution is Cloud-Resolving?
Authors: Craig George C. , Dörnbrack Andreas
Published: June 2008

Systematic numerical experiments were conducted to determine the spatial resolution required to resolve a moist thermal show convergence at a scale proportional to the smaller of the initial thermal diameter D0 and a buoyancy length scale Lbuoy. The buoyancy length scale Lbuoy = ΔT0/ΔΓ (ΔT0 is the initial buoyancy excess of the thermal and ΔΓ is the ambient stratification) describes the maximum vertical displacement that can be induced against the stratification in the environment by buoyancy-driven pressure perturbations in the cloud and, thus, the maximum scale of eddies that cross the cloud boundary. For typical atmospheric conditions in which the cloud size D0 is larger than Lbuoy, numerical simulations of the mixing processes in cumulus clouds must resolve Lbuoy.
A Method to Find Perturbations That Trigger Blocking Onset: Conditional Nonlinear Optimal Perturbations
Authors: Mu Mu , Jiang Zhina
Published: June 2008

In this paper the following question is addressed: assuming that some information is available about initial perturbations (e.g., that they belong to an ensemble, which consists of the perturbations whose magnitudes are less than a given value), how can one determine which perturbations belong to this ensemble and trigger the blocking onset? The applicability of linear singular vectors (LSVs) and conditional nonlinear optimal perturbations (CNOPs) is investigated by a T21L3 quasigeostrophic (QG) model and its tangent linear and adjoint versions. Particular attention is focused on the roles of nonlinear processes and the importance of choosing a proper objective function.

LSVs are the fastest-growing perturbations when the evolutions of the initial perturbations are well described by the tangent linear version of the nonlinear model. CNOPs are a natural generalization of LSVs into the nonlinear category, that is, the initial perturbation whose nonlinear evolution attains the maximum of the objective function at a prescribed forecast time under some initial constraint conditions. The results of this research show that in some cases for the given initial ensemble perturbations CNOPs trigger a transition to a blocking regime (whereas LSVs may not generate such a transition), which shows that nonlinear advection processes are fundamental for studying the weather regime transitions from zonal flow to blocking in the medium range.

By choosing two objective functions and investigating the resulting CNOPs, it is found that CNOPs obtained from the objective function of the blocking-index form (type-1 CNOPs) may trigger a transition to a blocking regime under some circumstances, whereas CNOPs related to the streamfunction squared norm (type-2 CNOPs) fail to yield such a transition. This demonstrates the importance of selecting a proper objective function when aiming at finding the perturbations yielding such a transition.

The mechanism of blocking onset triggered by perturbations is also explored. It is shown that the approach of type-1 CNOP remains a viable tool to capture the spatial structure of initial perturbations that trigger a blocking onset. The planetary-scale projection of the nonlinear interaction of such initial perturbations contributes to the amplification of the blocking downstream and then triggers a blocking onset.
Sensitivity of a Cloud-Resolving Model to Bulk and Explicit Bin Microphysical Schemes. Part I: Comparisons
Authors: Li Xiaowen , Tao Wei-Kuo , Khain Alexander P. , Simpson Joanne , Johnson Daniel E.
Published: June 2008

A two-dimensional cloud-resolving model is used to study the sensitivities of two microphysical schemes, a bulk scheme and an explicit spectral bin scheme, in simulating a midlatitude summertime squall line [Preliminary Regional Experiment for Storm-Scale Operational and Research Meteorology (PRE-STORM), 10–11 June 1985]. In this first part of a two-part paper, the developing and mature stages of simulated storms are compared in detail. Some variables observed during the field campaign are also presented for validation. It is found that both schemes agree well with each other, and also with published observations and retrievals, in terms of storm structures and evolution, average storm flow patterns, pressure and temperature perturbations, and total heating profiles. The bin scheme is able to produce a much more extensive and homogeneous stratiform region, which compares better with observations.

However, instantaneous fields and high temporal resolution analyses show distinct characteristics in the two simulations. During the mature stage, the bulk simulation produces a multicell storm with convective cells embedded in its stratiform region. Its leading convection also shows a distinct life cycle (strong evolution). In contrast, the bin simulation produces a unicell storm with little temporal variation in its leading cell regeneration (weak evolution). More detailed, high-resolution observations are needed to validate and, perhaps, generalize these model results. Interactions between the cloud microphysics and storm dynamics that produce the sensitivities described here are discussed in detail in Part II of this paper.
Sensitivity of a Cloud-Resolving Model to Bulk and Explicit Bin Microphysical Schemes. Part II: Cloud Microphysics and Storm Dynamics Interactions
Authors: Li Xiaowen , Tao Wei-Kuo , Khain Alexander P. , Simpson Joanne , Johnson Daniel E.
Published: June 2008

Part I of this paper compares two simulations, one using a bulk and the other a detailed bin microphysical scheme, of a long-lasting, continental mesoscale convective system with leading convection and trailing stratiform region. Diagnostic studies and sensitivity tests are carried out in Part II to explain the simulated contrasts in the spatial and temporal variations by the two microphysical schemes and to understand the interactions between cloud microphysics and storm dynamics. It is found that the fixed raindrop size distribution in the bulk scheme artificially enhances rain evaporation rate and produces a stronger near-surface cool pool compared with the bin simulation. In the bulk simulation, cool pool circulation dominates the near-surface environmental wind shear in contrast to the near-balance between cool pool and wind shear in the bin simulation. This is the main reason for the contrasting quasi-steady states simulated in Part I. Sensitivity tests also show that large amounts of fast-falling hail produced in the original bulk scheme not only result in a narrow trailing stratiform region but also act to further exacerbate the strong cool pool simulated in the bulk parameterization.

An empirical formula for a correction factor, r(qr) = 0.11qr−1.27 + 0.98, is developed to correct the overestimation of rain evaporation in the bulk model, where r is the ratio of the rain evaporation rate between the bulk and bin simulations and qr(g kg−1) is the rain mixing ratio. This formula offers a practical fix for the simple bulk scheme in rain evaporation parameterization.
A Simple Stochastic Model for Generating Broken Cloud Optical Depth and Cloud-Top Height Fields
Authors: Prigarin Sergei M. , Marshak Alexander
Published: June 2008

A simple and fast algorithm for generating two correlated stochastic two-dimensional (2D) cloud fields is described. The algorithm is illustrated with two broken cumulus cloud fields: cloud optical depth and cloud-top height retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS). Only two 2D fields are required as an input. The algorithm output is statistical realizations of these two fields with approximately the same correlation and joint distribution functions as the original ones. The major assumption of the algorithm is statistical isotropy of the fields. In contrast to fractals and the Fourier filtering methods frequently used for stochastic cloud modeling, the proposed method is based on spectral models of homogeneous random fields. To retain the same probability density function as the (first) original field, the method of inverse distribution function is used. When the spatial distribution of the first field has been generated, a realization of the correlated second field is simulated using a conditional distribution matrix. This paper serves as a theoretical justification of the publicly available software “Simulation of a two-component cloud field,” which has been recently released. Although 2D rather than full 3D, the stochastic realizations of two correlated cloud fields that mimic statistics of given fields have proven to be very useful to study 3D radiative transfer features of broken cumulus clouds for a better understanding of shortwave radiation and the interpretation of remote sensing retrievals.
Diminutive Frontal Waves—A Link between Fronts and Cyclones
Authors: Hewson Tim D.
Published: June 2008

A number of recent publications have dealt with cyclone identification and tracking. Following on, this paper extends the typical cyclone life cycle back in time to embrace a new feature called a “diminutive frontal wave.” One aim is to improve predictability by extending tracks. This is particularly important for small, cyclonic windstorms, which can often be missed in postprocessed output from operational, ensemble, and climate runs.

The recognition of diminutive waves requires a new, front-relative, low-level vorticity partition. The parts are labeled “frontal vorticity” and “disturbance vorticity” and are computed, respectively, from front-parallel and cross-front low-level wind components. A diminutive frontal wave then lies wherever there is a local, along-front maximum in the disturbance vorticity. Computations require local coordinates; these are conveniently provided, at all grid points, by objective front diagnostics.

Analysis of cyclone-type transitions over the North Atlantic in operational numerical model data confirms the validity of adding the diminutive wave stage to the revised cyclone life cycle. Examples then suggest that nonmodal growth of diminutive waves can occur, albeit with a sometimes complex interplay between separate cyclonic features. In all cases, model resolution is necessarily higher than the 100–500 km typically used in previous work.
Convectively Coupled Kelvin Waves over Tropical Africa during the Boreal Summer: Structure and Variability
Authors: Mekonnen Ademe , Thorncroft Chris D. , Aiyyer Anantha R. , Kiladis George N.
Published: June 2008

The structure and variability of convectively coupled Kelvin waves during the boreal summer are explored using satellite-observed brightness temperature data and ECMWF reanalyses. Kelvin wave activity is most prominent between the central and eastern Pacific, across Africa, and the Indian Ocean. Composite analysis shows that over sub-Saharan Africa Kelvin wave convection is peaked north of the equator, while the dynamical fields tend to be symmetric with respect to the equator. Convectively coupled Kelvin waves propagate faster over the Pacific and western Atlantic (∼24 m s−1), and slow down over tropical Africa (∼14 m s−1), consistent with stronger coupling between the dynamics and convection over tropical Africa. The Kelvin waves observed over Africa generally propagate into the region from anywhere between the eastern Pacific and the Atlantic, and decay over the eastern Indian Ocean basin.

Results show marked interannual variability of Kelvin wave activity over Africa. Anomalously high Kelvin wave variance tends to occur during dry years, while low variance occurs during wet years. African Kelvin wave activity is positively correlated with SST anomalies in the equatorial east Pacific. The same warm SST anomalies that are favorable for enhanced Kelvin wave activity suppress the mean rainfall over tropical Africa via a more slowly varying teleconnection and associated subsidence.

A brief analysis of an intense Kelvin wave in August 1987 (a dry year) shows a clear impact of the wave on convective development and daily rainfall over tropical Africa. This Kelvin wave was also associated with a series of easterly wave initiations over tropical Africa.
Anatomizing the Ocean’s Role in ENSO Changes under Global Warming*
Authors: Yang Haijun , Zhang Qiong
Published: June 2008

A revisit on observations shows that the tropical El Niño–Southern Oscillation (ENSO) variability, after removing both the long-term trend and decadal variation of the background climate, has been enhanced by as much as 50% during the past 50 yr. This is inconsistent with the changes in the equatorial atmosphere, which shows a slowdown of the zonal Walker circulation and tends to stabilize the tropical coupling system. The ocean role is highlighted in this paper. The enhanced ENSO variability is attributed to the strengthened equatorial thermocline that acts as a destabilizing factor of the tropical coupling system. To quantify the dynamic effect of the ocean on the ENSO variability under the global warming, ensemble experiments are performed using a coupled climate model [Fast Ocean Atmosphere Model (FOAM)], following the “1pctto2x” scenario defined in the Intergovernmental Panel on Climate Change (IPCC) reports. Term balance analyses on the temperature variability equation show that the anomalous upwelling of the mean vertical temperature gradient (referred as the “local term”) in the eastern equatorial Pacific is the most important destabilizing factor to the temperature variabilities. The magnitude of local term and its change are controlled by its two components: the mean vertical temperature gradient Tz and the “virtual vertical heat flux” −w′T ′. The former can be viewed as the background of the latter and these two components are positively correlated. A stronger Tz is usually associated with a bigger upward heat flux −w′T ′, which implies a bigger impact of thermocline depth variations on SST. The Tz is first enhanced during the transient stage of the global warming with a 1% yr−1 increase of CO2, and then reduced during the equilibrium stage with a fixed doubled CO2. This turnaround in Tz determines the turnaround of ENSO variability in the entire global warming period.
Arctic Total Water Vapor: Comparison of Regional Climate Simulations with Observations, and Simulated Decadal Trends
Authors: Rinke A. , Melsheimer C. , Dethloff K. , Heygster G.
Published: June 2008

Satellite-retrieved data of total water vapor (TWV) over the Arctic are patchy, with large areas of missing data because of various limitations of the retrieval algorithms. To overcome these observational difficulties, a new retrieval algorithm has been developed that allows for monitoring the TWV over the Arctic during most of the year. This method retrieves TWV from satellite microwave radiometer data [the Advanced Microwave Sounding Unit B (AMSU-B)]. These new data have been made available for 4 yr (2000–03) and have been used to evaluate high-resolution simulations with the Arctic regional atmospheric climate model HIRHAM at daily, monthly, and seasonal time scales. The strong dynamic TWV variability on the daily time scale, linked with moisture transport by weather systems, is discussed for selected case studies. Both the simulated climatological seasonal mean patterns and the variability on interannual and decadal time scales are in agreement with those of the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data. Trends in Arctic TWV for 1958–2001, broken down by season, are presented. Although an increase in the TWV is obvious in all seasons, there are also regions where a decreasing trend appears. Significant maximum positive trends are calculated over the western Arctic in summer (up to 0.06 kg m−2 yr−1), and a significant small negative trend is calculated over the East Siberian Sea in winter.
Passage of a Barotropic Vortex through a Gap
Authors: Duran-Matute M. , Fuentes O. U. Velasco
Published: June 2008

The flow of a vortex advected by a uniform current toward a gap in a straight barrier is studied. This is an idealization of flows observed in the world’s oceans, for example, in the Yucatan Channel and in the various passages of the Lesser Antilles. The vortex evolution and the transport properties are studied as a function of three nondimensional parameters related to the vortex intensity, the vortex initial position, and the gap’s span. The flow evolution is computed numerically with a two-dimensional inviscid model. The vortex is observed to behave in one of the following ways: it passes completely through the gap, it splits and only a fraction passes, or it stays entirely in the upstream side of the wall. In each of these regimes, transport and mixing are analyzed using the Lagrangian flow geometry, finite-size Lyapunov exponents, and residence times of fluid particles. Laboratory experiments are performed in a homogeneous, rotating fluid. In the region of parameter space that leads to total passage of the vortex, there is good agreement between the evolution observed in the laboratory and that obtained numerically. In the regions of parameter space, which lead to partial passage and full blockage, the agreement is good only until the generation of vorticity on the walls becomes important.
Quality Assessment of Weather Radar Wind Profiles during Bird Migration
Authors: Holleman Iwan , van Gasteren Hans , Bouten Willem
Published: June 2008

Wind profiles from an operational C-band Doppler radar have been combined with data from a bird tracking radar to assess the wind profile quality during bird migration. The weather radar wind profiles (WRWPs) are retrieved using the well-known volume velocity processing (VVP) technique. The X-band bird radar performed range–height scans perpendicular to the main migration direction and bird densities were deduced by counting and normalizing the observed echoes. It is found that the radial velocity standard deviation (σr) obtained from the VVP retrieval is a skillful indicator of bird migration. Using a threshold of 2 m s−1 on σr, more than 93% of the bird-contaminated wind vectors are rejected while over 70% of the true wind vectors are accepted correctly. For high bird migration densities the raw weather radar wind vectors have a positive speed bias of 8.6 ± 3.8 m s−1, while the quality-controlled wind vectors have a negligible speed bias. From the performance statistics against a limited area numerical weather prediction model, it is concluded that all (significant) bird contamination is removed and that high-quality weather radar wind profiles can be obtained, even during the bird migration season.
The Spatial Distribution and Evolution Characteristics of North Atlantic Cyclones
Authors: Dacre H. F. , Gray S. L.
Published: June 2008

A climatology of extratropical cyclones is produced using an objective method of identifying cyclones based on gradients of 1-km height wet-bulb potential temperature. Cyclone track and genesis density statistics are analyzed and this method is found to compare well with other cyclone identification methods. The North Atlantic storm track is reproduced along with the major regions of genesis. Cyclones are grouped according to their genesis location and the corresponding lysis regions are identified. Most of the cyclones that cross western Europe originate in the east Atlantic where the baroclinicity and the sea surface temperature gradients are weak compared to the west Atlantic. East Atlantic cyclones also have higher 1-km height relative vorticity and lower mean sea level pressure at their genesis point than west Atlantic cyclones. This is consistent with the hypothesis that they are secondary cyclones developing on the trailing fronts of preexisting “parent” cyclones. The evolution characteristics of composite west and east Atlantic cyclones have been compared. The ratio of their upper- to lower-level forcing indicates that type B cyclones are predominant in both the west and east Atlantic, with strong upper- and lower-level features. Among the remaining cyclones, there is a higher proportion of type C cyclones in the east Atlantic, whereas types A and C are equally frequent in the west Atlantic.
Surface Characteristics of Observed Cold Pools
Authors: Engerer Nicholas A. , Stensrud David J. , Coniglio Michael C.
Published: June 2008

Cold pools are a key element in the organization of precipitating convective systems, yet knowledge of their typical surface characteristics is largely anecdotal. To help to alleviate this situation, cold pools from 39 mesoscale convective system (MCS) events are sampled using Oklahoma Mesonet surface observations. In total, 1389 time series of surface observations are used to determine typical rises in surface pressure and decreases in temperature, potential temperature, and equivalent potential temperature associated with the cold pool, and the maximum wind speeds in the cold pool. The data are separated into one of four convective system life cycle stages: first storms, MCS initiation, mature MCS, and MCS dissipation. Results indicate that the mean surface pressure rises associated with cold pools increase from 3.2 hPa for the first storms’ life cycle stage to 4.5 hPa for the mature MCS stage before dropping to 3.3 hPa for the dissipation stage. In contrast, the mean temperature (potential temperature) deficits associated with cold pools decrease from 9.5 (9.8) to 5.4 K (5.6 K) from the first storms to the dissipation stage, with a decrease of approximately 1 K associated with each advance in the life cycle stage. However, the daytime and early evening observations show mean temperature deficits over 11 K. A comparison of these observed cold pool characteristics with results from idealized numerical simulations of MCSs suggests that observed cold pools likely are stronger than those found in model simulations, particularly when ice processes are neglected in the microphysics parameterization. The mean deficits in equivalent potential temperature also decrease with the MCS life cycle stage, starting at 21.6 K for first storms and dropping to 13.9 K for dissipation. Mean wind gusts are above 15 m s−1 for all life cycle stages. These results should help numerical modelers to determine whether the cold pools in high-resolution models are in reasonable agreement with the observed characteristics found herein. Thunderstorm simulations and forecasts with thin model layers near the surface are also needed to obtain better representations of cold pool surface characteristics that can be compared with observations.
MOS Uncertainty Estimates in an Ensemble Framework
Authors: Glahn Bob , Peroutka Matthew , Wiedenfeld Jerry , Wagner John , Zylstra Greg , Schuknecht Bryan , Jackson Bryan
Published: June 2008

It is being increasingly recognized that the uncertainty in weather forecasts should be quantified and furnished to users along with the single-value forecasts usually provided. Probabilistic forecasts of “events” have been made in special cases; for instance, probabilistic forecasts of the event defined as 0.01 in. or more of precipitation at a point over a specified time period [i.e., the probability of precipitation (PoP)] have been disseminated to the public by the Weather Bureau/National Weather Service since 1966. Within the past decade, ensembles of operational numerical weather prediction models have been produced and used to some degree to provide probabilistic estimates of events easily dealt with, such as the occurrence of specific amounts of precipitation. In most such applications, the number of ensembles restricts this “enumeration” method, and the ensembles are characteristically underdispersive. However, fewer attempts have been made to provide a probability density function (PDF) or cumulative distribution function (CDF) for a continuous variable. The Meteorological Development Laboratory (MDL) has used the error estimation capabilities of the linear regression framework and kernel density fitting applied to individual and aggregate ensemble members of the Global Ensemble Forecast System of the National Centers for Environmental Prediction to develop PDFs and CDFs. This paper describes the method and results for temperature, dewpoint, daytime maximum temperature, and nighttime minimum temperature. The method produces reliable forecasts with accuracy exceeding the raw ensembles. Points on the CDF for 1650 stations have been mapped to the National Digital Forecast Database 5-km grid and an example is provided.
Emergency Management Decision Making during Severe Weather
Authors: Baumgart Leigh A. , Bass Ellen J. , Philips Brenda , Kloesel Kevin
Published: June 2008

Emergency managers make time-sensitive decisions in order to protect the public from threats including severe weather. Simulation and questionnaires were used to capture the decision-making process of emergency managers during severe weather events. These data were combined with insights from emergency manager instructors, National Weather Service (NWS) forecasters, and experienced emergency managers to develop a descriptive decision-making model of weather information usage, weather assessments, and decisions made during severe weather. This decision-making model can be used to develop better decision support tools, improve training, and to understand how innovative weather information could potentially affect emergency managers’ role of protecting the public.
ADHD: Does Parenting Style Matter?
Authors: Modesto-Lowe Vania , Danforth Jeffrey S. , Brooks Donna
Published: June 2008

Attention deficit hyperactivity disorder (ADHD) is a condition typically arising in childhood, which untreated, can have consequences reaching into adolescence and beyond. Effective pharmacological treatment is available and has become widespread in the West. Outcomes for both the child with ADHD and the parent may be influenced by the nature of interaction between them. The authors of this article aim to review published research examining the interaction between parents and their children with ADHD. A PubMed search was conducted of studies written in English between 2000 and 2007 with the keywords ADHD and parenting. Child ADHD elicits high levels of parental stress and maladaptive parenting. The presence of parental psychopathology is common and influences the parent's response to the child's ADHD symptoms. Optimizing parent—child interaction and parental psychiatric status may improve outcomes for both parent and child.
Pathogens Causing Recurrent and Difficult-to-Treat Acute Otitis Media, 2003-2006
Authors: Pichichero Michael E. , Casey Janet R. , Hoberman Alejandro , Schwartz Richard
Published: June 2008

This study sought to determine the microbiology of recurrent acute otitis media (AOM) and AOM treatment failure (AOMTF) in the context of widespread use of heptavalent pneumococcal conjugate vaccine (PCV7). In this retrospective cohort study, 244 AOM isolates obtained by tympanocentesis during 3 respiratory seasons—2003-2004 (n = 126), 2004-2005 (n = 52), 2005-2006 (n = 66)—from three geographically diverse pediatric populations were compared. Most isolates were from children less than 2 years old, who had received PCV7. For the 3 seasons the proportion of Streptococcus pneumoniae isolates was 35%, 35%, and 46% and for Haemophilus influenzae was 55%, 58%, and 39%, respectively (change in trend, P = .09). A total of 37%, 39%, and 50% of S. pneumoniae were penicillin nonsusceptible (PNSP) and 48%, 67%, and 50% of H. influenzae produced β-lactamase, respectively. Although H. influenzae remains the most frequently isolated pathogen in children with AOMTF or recurrent AOM, S. pneumoniae that are PNSP are reemerging as important organisms.
Employment Self-Disclosure Rates and Rationales of University Graduates With Learning Disabilities
Authors: Madaus Joseph W.
Published: June 2008

Five hundred graduates with learning disabilities (LD) from three universities in the United States completed a survey related to their postschool employment outcomes and experiences. The present study presents data related to their decisions regarding LD disclosure in employment settings. Although 73% of the respondents reported that the LD affected their job in some way, only 55% reported self-disclosing, and only 12% reported requesting accommodations. Specific reasons for each of these decisions are presented, as are areas in which LD affect work, strategies for dealing with LD in the workplace, and perceptions of the Americans with Disabilities Act. Implications for secondary and postsecondary programs are discussed.
Interventions for Reading Difficulties
Authors: Lovett Maureen W. , De Palma Maria , Frijters Jan , Steinbach Karen , Temple Meredith , Benson Nancy , Lacerenza Léa
Published: June 2008

This article explores whether struggling readers from different primary language backgrounds differ in response to phonologically based remediation. Following random assignment to one of three reading interventions or to a special education reading control program, reading and reading-related outcomes of 166 struggling readers were assessed before, during, and following 105 intervention hours. Struggling readers met criteria for reading disability, were below average in oral language and verbal skills, and varied in English as a first language (EFL) versus English-language learner (ELL) status. The research-based interventions proved superior to the special education control on both reading outcomes and rate of growth. No differences were revealed for children of EFL or ELL status in intervention outcomes or growth during intervention. Oral language abilities at entry were highly predictive of final outcomes and of reading growth during intervention, with greater language impairment being associated with greater growth.
Effects of Polarity on Electrospinning Process
Authors: Kilic Ali , Oruc Fatih , Demir Ali
Published: June 2008

As one of the nanofiber production processes, the electrospinning process has a conventional configuration consisting of a charged syringe and a grounded collector plate. In this study, the polarities of the electrodes are reversed so that while the collector is charged by power supply, the syringe is grounded. A solution of 7.5 wt % polyvinyl (alcohol)/water is electrospun. The conventional setup and the new inverse setup are compared in terms of production efficiency and the diameter of the nanofibers is produced. Thus, it is aimed to determine which configuration best suits for an extruder-collector system in an industrial context. Results showed that the conventional setup has a noticeably higher nanofiber production efficiency than the new setup due to a lack of Coulombic force acting on the polymer jet in the new setup. Also, nanofiber diameters and web layer pore sizes produced by the conventional setup are much finer and more homogenously distributed than those produced by the new reversed setup.
Static Tearing, Part I: Its Significance in the Light of European Standards
Authors: Witkowska Beata , Frydrych Iwona
Published: June 2008

Static tearing is one of the most common types of failure in textile fabrics and determines the durability of an article. The tear resistance is the strength parameter, which characterizes the textile product with respect to its resistance to outer mechanical forces. In the presented work, we describe in detail the problem of static tear strength in woven fabrics. In the first part, the meaning of the tear strength in an assessment of textiles, particularly with reference to the present day, is presented.