bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of exercise stress testing, diurnal variation and temporal decline on circulating progenitor cells
Authors: Karthikeyan Vellore , Jessani Shahirose , Goon Patrick , Watson Timothy , Shantsila Eduard , Lip Gregory
Published: November 2009

Endothelial damage/dysfunction is involved in numerous cardiovascular disease processes. Given that the mature endothelial cells have limited capacity for self regeneration, circulating progenitor cells (CPCs) may modulate the balance between vascular damage and regeneration. The three aims of the present study were 1) to define the influence of exercise treadmill testing (ETT) on peripheral CPC levels; 2) to assess the diurnal variation of CPC counts; and 3) to investigate the rate of temporal decline in CPCs once ex vivo. The dynamics of CPC count changes following an ETT were assessed on consecutive 20 patients referred to our ‘rapid-access’ chest pain clinic (70% male, age 69.9 ± 7.8) with venous blood samples taken pre-exercise, immediately post-exercise and at 30 minutes post-exercise. Diurnal variation in CPCs was assessed in 13 stable in-hospital patients (46% male, age 69.1 ± 7.5 years) with blood samples were taken five times every 6 hours. To investigate the temporal decline, blood samples from 12 patients (58.3% male, age 69.9 ± 7.9 years) were reprocessed for CPC counts at 4 hours and at 24 hours after sample collection. Plasma levels of von Willebrand factor (vWf) and soluble E-selectin (sE-selectin) were assessed by ELISA. CPCs were enumerated with flow cytometry as CD34+, CD133+, CD45dim events. Exercise led to significant increases in vWF and sE-selectin levels, but no significant influence on CPC counts were observed. Baseline CPC numbers demonstrated a negative correlation with vWf (r=-0.551, p=0.012) and sE-selectin levels (r=-0.494, p=0.027). CPC counts showed a significant diurnal variation, being significantly higher at 12 a.m. compared to 12 p.m. (p=0.046) and 6 p.m. (p=0.023). A 4 hour delay in sample preparation did not affect CPCs counts, but there was a significant decline in CPC recovery when sample processing was delayed by 24 hours (p<0.05). Routine exercise stress testing does not significantly affect CPC counts. Peripheral CPC levels showed a significant diurnal variation. Delays in sample preparation for CPC counts should be avoided as they may influence the accuracy of the test by resulting in a significant decline in CPC recovery. Thus, various factors may affect accuracy of CPC enumeration that may limit their role as a reliable clinical marker and biomarker of endothelial damage.
Aspirin therapy: An attempt to explain the events of prothrombotic complications after treatment discontinuation
Authors: Aguejouf Omar , Desplat Vanessa , Eizayaga Francisco , Doutremepuich Christian
Published: November 2009

Aspirin remains the most widely used drug for prevention of vascular events. Recent observational epidemiological evidence has raised the concern that aspirin withdrawal for treatment non-compliance, surgery or side effects can carry an increased thrombotic risk. The delay to the thrombotic event was between 7 to 30 days in most reports and most frequently 7 to 10 days. The mechanism underlying this effect remains poorly understood. Using an in vivo model of laser-induced thrombosis, aspirin injected in one single dose of 100 mg/kg bw has also shown a prothrombotic activity in the rat 8 to 10 days after injection in the normal rat. The hypothesis was made that minimal concentrations of aspirin or ultra-low dose aspirin (ULDA) could induce this effect. ULDA showed prothrombotic properties in the same model of induced thrombosis that were very similar to those described after aspirin withdrawal, but the effect was observed only one hour after aspirin administration. This prothrombotic effect of ULDA is very similar to the effect observed after COX 2 selective inhibition with NS 398. The administration of both the selective COX 2 inhibitor and ULDA did not produce further changes. High-dose ASA counterbalances the lack of COX 2 with an antithrombotic effect. No effect of residual ASA was observed in COX 2 -/- mice, thus confirming the existence of a COX 2 inhibition pathway. COX 2 inhibition produced by residual ASA is the probable cause of ischaemic accidents and drug-eluting stents thrombosis a few days after ASA withdrawal.
TRPC channels in vascular cell function
Authors: Gudermann Thomas , Dietrich Alexander , Kalwa Hermann
Published: November 2009

The mammalian transient receptor potential (TRP) superfamily of non-selective cation channels can be divided into six major families. Among them, the “classical” or “canonical” TRPC family is most closely related to Drosophila TRP, the founding member of the superfamily. All seven channels of this family designated TRPC1–7 share the common property of receptor-operated activation through phospholipase C (PLC)-coupled receptors, but their regulation by store-dependent mechanisms involving the proteins STIM and ORAi is still discussed controversially. This review will focus on the proposed functions of TRPC proteins in cells of the vascular system (e.g. platelets, smooth muscle cells and endothelial cells) and will present data concerning their physiological functions analysed in isolated tissues with down-regulated channel activity and in gene-deficient mouse models.
Hantavirus regulation of endothelial cell functions
Authors: Gavrilovskaya Irina , Mackow Erich
Published: November 2009

Hantaviruses cause two vascular permeability-based diseases and primarily infect endothelial cells which form the primary fluid barrier of the vasculature. Since hantavirus infections are not lytic, the mechanisms by which hantaviruses cause haemorrhagic fever with renal syndrome (HFRS) or Hantavirus Pulmonary Syndrome (HPS) are indeterminate. HPS is associated with acute pulmonary oedema and HFRS with moderate haemorrhage and renal sequelae, perhaps reflecting the location of vast microvascular beds and endothelial cell reservoirs available for hantavirus infection. Endothelial cells regulate capillary integrity, and hantavirus infection provides a primary means for alteing vascular permeability that contributes to pathogenesis. The central importance of endothelial cells in regulating oedema, vascular repair, angiogenesis, immune cell recruitment, platelet deposition as well as gas exchange and solute delivery suggest that a multitude of inputs and cellular responses may be influenced by hantavirus infection and contribute to pathogenic changes in vascular permeability. Here we focus on understanding hantavirus interactions with endothelial cells which are linked to vascular permeability, and provide insight into the contribution of endothelial cell responses in hantavirus pathogenesis.
Impaired Heart Rate Recovery and Chronotropic Incompetence in Patients With Heart Failure With Preserved Ejection Fraction
Authors: Phan Thanh Trung , Shivu Ganesh Nallur , Abozguia Khalid , Davies Chris , Nassimizadeh Mohammad , Jimenez Donie , Weaver Rebekah , Ahmed Ibrar , Frenneaux Michael
Published: November 2009

Background—

This study assessed the chronotropic response to exercise and heart rate (HR) recovery after exercise in a carefully phenotyped group of patients with heart failure with preserved left ventricular ejection fraction (HfpEF) and a control group of similar age and gender distribution.

Methods and Results—

We studied 41 patients with HfpEF, 41 healthy controls, and 16 hypertensive controls. None were taking HR-limiting medications. All study participants had clinical examination, 12-lead ECG, pulmonary function test, echocardiogram, and metabolic exercise test with HR monitoring throughout exercise. Chronotropic response was measured by the percentage of the HR reserve used during maximal exercise and the peak exercise HR as a percentage of predicted maximal HR. Patients with HfpEF were generally women (70%), overweight, aged 69±8 years. Controls were of similar gender (63%) and age (67±6 years). Patients with HfpEF had significantly reduced peak VO
2
compared with controls (20±4 mL · kg
−1
· min
−1
versus 31±6 mL · kg
−1
· min
−1
,
P
<0.001) and greater minute ventilation-carbon dioxide production relationship (V
e
/V
co
2
slope) (33±6 versus 29±4,
P
<0.001). Chronotropic incompetence was significantly more common in patients with HfpEF compared with matched healthy controls as measured by the percentage of the HR reserve used during maximal exercise (63% versus 2%, <0.001) and percentage of predicted maximal HR (34% versus 2%, <0.001). In addition, abnormal HR recovery 1-minute after exercise (defined as the reduction in the HR from peak exercise 1-minute after exercise) was also significantly more common in patients with HfpEF compared with controls (23% versus 2%,
P
=0.01). Hypertensive controls showed similar chronotropic response to peak exercise and HR recovery after exercise as healthy controls.

Conclusions—

Patients with HfpEF have impaired chronotropic incompetence during maximal exercise and abnormal HR recovery after exercise.
Distribution of 10-Year and Lifetime Predicted Risks for Cardiovascular Disease in US Adults
Authors: Marma Amanda K. , Berry Jarett D. , Ning Hongyan , Persell Stephen D. , Lloyd-Jones Donald M.
Published: November 2009

Background—

National guidelines for primary prevention suggest consideration of lifetime risk for cardiovascular disease in addition to 10-year risk, but it is currently unknown how many US adults would be identified as having low short-term but high lifetime predicted risk if stepwise stratification were used.

Methods and Results—

We included 6329 cardiovascular disease–free and nonpregnant individuals ages 20 to 79 years, representing approximately 156 million US adults, from the National Health and Nutrition Examination Survey 2003 to 2004 and 2005 to 2006. We assigned 10-year and lifetime predicted risks to stratify participants into 3 groups: low 10-year (<10%)/low lifetime (<39%) predicted risk, low 10-year (<10%)/high lifetime (≥39%) predicted risk, and high 10-year (≥10%) predicted risk or diagnosed diabetes. The majority of US adults (56%, or 87 million individuals) are at low short-term but high lifetime predicted risk for cardiovascular disease. Twenty-six percent (41 million adults) are at low short-term and low lifetime predicted risk, and only 18% (28 million individuals) are at high short-term predicted risk. The addition of lifetime risk estimation to 10-year risk estimation identifies higher-risk women and younger men in particular.

Conclusions—

Whereas 82% of US adults are at low short-term risk, two thirds of this group, or 87 million people, are at high lifetime predicted risk for cardiovascular disease. These results provide support for use of a stepwise stratification system aimed at improving risk communication, and they provide a baseline for public health efforts aimed at increasing the proportion of Americans with low short-term and low lifetime risk for cardiovascular disease.
Prognostic Implications of Myocardial Perfusion Single-Photon Emission Computed Tomography in the Elderly
Authors: Hachamovitch Rory , Kang Xingping , Amanullah Aman M. , Abidov Aiden , Hayes Sean W. , Friedman John D. , Cohen Ishac , Thomson Louise E.J. , Germano Guido , Berman Daniel S.
Published: November 2009

Background—

The goal of this study was to assess the clinical value of stress myocardial perfusion scintigraphy (MPS) in elderly patients (≥75 years of age).

Methods and Results—

We followed up 5200 elderly patients (41% exercise) after dual-isotope MPS over 2.8±1.7 years (362 cardiac deaths [CDs], 7.0%, 2.6%/y) and a subset with extended follow-up (684 patients for 6.2±2.9 years; 320 all-cause deaths). Survival modeling of CD revealed that both MPS-measured ischemia and fixed defect added incrementally to pre-MPS data in both adenosine and exercise stress patients. Modeling a subset with gated MPS (n=2472) revealed that ejection fraction and perfusion data added incrementally to each other, further enhancing risk stratification. Unadjusted, annualized post–normal MPS CD rate was 1.3% but <1% in patients with normal rest ECG, exercise stress, or age of 75 to 84 years and was 2.3% to 3.7% in patients ≥85 years of age or undergoing pharmacological stress. However, compared with age-matched US population CD rates (75 to 84 years of age, 1.5%; ≥85 years, 4.8%), normal MPS CD rates were approximately one-third lower than the baseline risk of US individuals (both
P
<0.05). Modeling of all-cause death in 684 patients with extended follow-up revealed that after risk adjustment, an interaction between early treatment and ischemia was present; increasing ischemia was associated with increasing survival with early revascularization, whereas in the setting of little or no ischemia, medical therapy had improved outcomes.

Conclusions—

Stress MPS effectively stratifies CD risk in elderly patients and may identify optimal post-MPS therapy. CD rates after normal MPS are low in all subsets in relative terms compared with the age-matched US population.
Vascular Endothelial-Specific Dimethylarginine Dimethylaminohydrolase-1–Deficient Mice Reveal That Vascular Endothelium Plays an Important Role in Removing Asymmetric Dimethylarginine
Authors: Hu Xinli , Xu Xin , Zhu Guangshuo , Atzler Dorothee , Kimoto Masumi , Chen Ju , Schwedhelm Edzard , Lüneburg Nicole , Böger Rainer H. , Zhang Ping , Chen Yingjie
Published: November 2009

Background—

Asymmetrical methylarginines inhibit NO synthase activity and thereby decrease NO production. Dimethylarginine dimethylaminohydrolase 1 (DDAH1) degrades asymmetrical methylarginines. We previously demonstrated that in the heart DDAH1 is predominantly expressed in vascular endothelial cells. Because an earlier study showed that mice with global DDAH1 deficiency experienced embryonic lethality, we speculated that a mouse strain with selective vascular endothelial DDAH1 deficiency (endo-DDAH1
−/−
) would largely abolish tissue DDAH1 expression in many tissues but possibly avoid embryonic lethality.

Methods and Results—

By using the LoxP/Cre approach, we generated the endo-DDAH1
−/−
mice. The endo-DDAH1
−/−
mice had no apparent defect in growth or development compared with wild-type littermates. DDAH1 expression was greatly reduced in kidney, lung, brain, and liver, indicating that in these organs DDAH1 is distributed mainly in vascular endothelial cells. The endo-DDAH1
−/−
mice showed a significant increase of asymmetric dimethylarginine concentration in plasma (1.41 μmol/L in the endo-DDAH1
−/−
versus 0.69 μmol/L in the control mice), kidney, lung, and liver, which was associated with significantly increased systolic blood pressure (132 mm Hg versus 113 mm Hg in wild-type). The endo-DDAH1
−/−
mice also exhibited significantly attenuated acetylcholine-induced NO production and vessel relaxation in isolated aortic rings.

Conclusions—

Our study demonstrates that DDAH1 is highly expressed in vascular endothelium and that endothelial DDAH1 plays an important role in regulating blood pressure. In the context that asymmetric methylarginines are broadly produced by many type of cells, the strong DDAH1 expression in vascular endothelium demonstrates for the first time that vascular endothelium can be an important site to actively dispose of toxic biochemical molecules produced by other types of cells.
Validation of Magnetic Resonance Myocardial Perfusion Imaging With Fractional Flow Reserve for the Detection of Significant Coronary Heart Disease
Authors: Watkins Stuart , McGeoch Ross , Lyne Jonathan , Steedman Tracey , Good Richard , McLaughlin Mairi-Jean , Cunningham Tony , Bezlyak Vladimir , Ford Ian , Dargie Henry J. , Oldroyd Keith G.
Published: November 2009

Background—

Magnetic resonance myocardial perfusion imaging (MRMPI) has a number of advantages over the other noninvasive tests used to detect reversible myocardial ischemia. The majority of previous studies have generally used quantitative coronary angiography as the gold standard to assess the accuracy of MRMPI; however, only an approximate relationship exists between stenosis severity and functional significance. Pressure wire–derived fractional flow reserve (FFR) values <0.75 correlate closely with objective evidence of reversible ischemia. Accordingly, we have compared MRMPI with FFR.

Methods and Results—

One hundred three patients referred for investigation of suspected angina underwent MRMPI with a 1.5-T scanner. The stress agent was intravenous adenosine (140 μg · kg
−1
· min
−1
), and the first-pass bolus contained 0.1 mmol/kg gadolinium. In the following week, coronary angiography with pressure wire studies was performed. FFR was recorded in all patent major epicardial coronary arteries, with a value <0.75 denoting significant stenosis. MRMPI scans, analyzed by 2 blinded observers, identified perfusion defects in 121 of 300 coronary artery segments (40%), of which 110 had an FFR <0.75. We also found that 168 of 179 normally perfused segments had an FFR ≥0.75. The sensitivity and specificity of MRMPI for the detection of functionally significant coronary heart disease were 91% and 94%, respectively, with positive and negative predictive values of 91% and 94%.

Conclusion—

MRMPI can detect functionally significant coronary heart disease with excellent sensitivity, specificity, and positive and negative predictive values compared with FFR.
High Residual Platelet Reactivity After Clopidogrel Loading and Long-Term Clinical Outcome After Drug-Eluting Stenting for Unprotected Left Main Coronary Disease
Authors: Migliorini Angela , Valenti Renato , Marcucci Rossella , Parodi Guido , Giuliani Gabriele , Buonamici Piergiovanni , Cerisano Giampaolo , Carrabba Nazario , Gensini Gian Franco , Abbate Rosanna , Antoniucci David
Published: November 2009

Background—

No data exist about the impact of high residual platelet reactivity (HRPR) after clopidogrel loading on long-term clinical outcome in patients undergoing drug-eluting stent (DES) implantation for unprotected left main disease (ULMD).

Methods and Results—

Consecutive patients who underwent percutaneous coronary intervention for ULMD had prospective platelet reactivity assessment by light transmittance aggregometry after a loading dose of 600 mg of clopidogrel. The primary end point of the study was cardiac mortality, and the secondary end point was stent thrombosis. From January 2005 to September 2008, 215 consecutive patients were treated with DES for ULMD. The incidence of HRPR after clopidogrel loading was 18.6%. The median follow-up was 19.3 months. The overall estimated 1-, 2- and 3-year cardiac mortality rate was 3.9±1.3%, 7.5±2.2%, and 12.2±3.4%, respectively. The 3-year cardiac mortality rate was 8.0±3.1% in the low residual platelet reactivity (LRPR) group and 28.3±10.4% in the HRPR group (
P
=0.005). The 3-year stent thrombosis rate was 4.2±1.8% in the low residual platelet reactivity group and 16.0±7.3% in the HRPR group (
P
=0.021). By forward stepwise regression analysis, HRPR after clopidogrel loading was the only independent predictor of cardiac death (hazard ratio, 3.82; 95% confidence interval,1.38 to 10.54;
P
=0.010) and stent thrombosis (hazard ratio, 3.69; 95% confidence interval, 1.12 to 12.09;
P
=0.031).

Conclusions—

HRPR after 600-mg clopidogrel loading is a strong marker of increased risk of cardiac death and DES thrombosis in patients receiving DES stenting for ULMD. Routine assessment of in vitro residual platelet reactivity after clopidogrel loading in patients with ULMD potentially suitable for DES-supported percutaneous coronary intervention should be considered to guide patient care decisions.
B-Type Natriuretic Peptides and Cardiovascular Risk
Authors: Di Angelantonio Emanuele , Chowdhury Rajiv , Sarwar Nadeem , Ray Kausik K. , Gobin Reeta , Saleheen Danish , Thompson Alexander , Gudnason Vilmundur , Sattar Naveed , Danesh John
Published: November 2009

Background—

Measurement of B-type natriuretic peptide (BNP) concentration or its precursor (N-terminal fragment [NT-proBNP]) is recommended in patients with symptoms of left ventricular dysfunction and in other settings, but the relevance of these peptides to cardiovascular disease (CVD) in general populations or in patients with stable vascular disease is uncertain.

Methods and Results—

Data were collated from 40 long-term prospective studies involving a total of 87 474 participants and 10 625 incident CVD outcomes. In a comparison of individuals in the top third with those in the bottom third of baseline values of natriuretic peptides, the combined risk ratio (RR), adjusted for several conventional risk factors, was 2.82 (95% confidence interval [CI], 2.40 to 3.33) for CVD. Analysis of the 6 studies with at least 250 CVD outcomes (which should be less prone to selective reporting than are smaller studies) yielded an adjusted RR of 1.94 (95% CI, 1.57 to 2.39). RRs were broadly similar with BNP or NT-proBNP (RR, 2.89 [95% CI, 1.91 to 4.38] and 2.82 [95% CI, 2.35 to 3.38], respectively) and by different baseline vascular risk (RR, 2.68 [95% CI, 2.07 to 3.47] in approximately general populations; RR, 3.35 [95% CI, 2.38 to 4.72] in people with elevated vascular risk factors; RR, 2.60 [95% CI, 1.99 to 3.38] in patients with stable CVD). Assay of BNP or NT-proBNP in addition to measurement of conventional CVD risk factors yielded generally modest improvements in risk discrimination.

Conclusions—

Available prospective studies indicate strong associations between circulating concentration of natriuretic peptides and CVD risk under a range of different circumstances. Further investigation is warranted, particularly in large general population studies, to clarify any predictive utility of these markers and to better control for publication bias.
The Commonality of Neural Networks for Verbal and Visual Short-term Memory
Authors: Majerus Steve , D'Argembeau Arnaud , Martinez Perez Trecy , Belayachi Sanaâ , Van der Linden Martial , Collette Fabienne , Salmon Eric , Seurinck Ruth , Fias Wim , Maquet Pierre
Published: November 2009

Although many neuroimaging studies have considered verbal and visual short-term memory (STM) as relying on neurally segregated short-term buffer systems, the present study explored the existence of shared neural correlates supporting verbal and visual STM. We hypothesized that networks involved in attentional and executive processes, as well as networks involved in serial order processing, underlie STM for both verbal and visual list information, with neural specificity restricted to sensory areas involved in processing the specific items to be retained. Participants were presented sequences of nonwords or unfamiliar faces, and were instructed to maintain and recognize order or item information. For encoding and retrieval phases, null conjunction analysis revealed an identical fronto-parieto-cerebellar network comprising the left intraparietal sulcus, bilateral dorsolateral prefrontal cortex, and the bilateral cerebellum, irrespective of information type and modality. A network centered around the right intraparietal sulcus supported STM for order information, in both verbal and visual modalities. Modality-specific effects were observed in left superior temporal and mid-fusiform areas associated with phonological and orthographic processing during the verbal STM tasks, and in right hippocampal and fusiform face processing areas during the visual STM tasks, wherein these modality effects were most pronounced when storing item information. The present results suggest that STM emerges from the deployment of modality-independent attentional and serial ordering processes toward sensory networks underlying the processing and storage of modality-specific item information.
Daytime Precipitation Estimation Using Bispectral Cloud Classification System
Authors: Behrangi Ali , Hsu Koulin , Imam Bisher , Sorooshian Soroosh
Published: November 2009

Two previously developed Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) algorithms that incorporate cloud classification system (PERSIANN-CCS) and multispectral analysis (PERSIANN-MSA) are integrated and employed to analyze the role of cloud albedo from Geostationary Operational Environmental Satellite-12 (GOES-12) visible (0.65 μm) channel in supplementing infrared (10.7 mm) data. The integrated technique derives finescale (0.04° × 0.04° latitude–longitude every 30 min) rain rate for each grid box through four major steps: 1) segmenting clouds into a number of cloud patches using infrared or albedo images; 2) classification of cloud patches into a number of cloud types using radiative, geometrical, and textural features for each individual cloud patch; 3) classification of each cloud type into a number of subclasses and assigning rain rates to each subclass using a multidimensional histogram matching method; and 4) associating satellite gridbox information to the appropriate corresponding cloud type and subclass to estimate rain rate in grid scale. The technique was applied over a study region that includes the U.S. landmass east of 115°W. One reference infrared-only and three different bispectral (visible and infrared) rain estimation scenarios were compared to investigate the technique’s ability to address two major drawbacks of infrared-only methods: 1) underestimating warm rainfall and 2) the inability to screen out no-rain thin cirrus clouds. Radar estimates were used to evaluate the scenarios at a range of temporal (3 and 6 hourly) and spatial (0.04°, 0.08°, 0.12°, and 0.24° latitude–longitude) scales. Overall, the results using daytime data during June–August 2006 indicate that significant gain over infrared-only technique is obtained once albedo is used for cloud segmentation followed by bispectral cloud classification and rainfall estimation. At 3-h, 0.04° resolution, the observed improvement using bispectral information was about 66% for equitable threat score and 26% for the correlation coefficient. At coarser 0.24° resolution, the gains were 34% and 32% for the two performance measures, respectively.
Energy Flux and Wavelet Diagnostics of Secondary Mountain Waves
Authors: Woods Bryan K. , Smith Ronald B.
Published: November 2009

In recent years, aircraft data from mountain waves have been primarily analyzed using velocity and temperature power spectrum and momentum flux estimation. Herein it is argued that energy flux wavelets (i.e., pressure–velocity wavelet cross-spectra) provide a more powerful tool for locating and classifying different types of mountain waves. In the first part of the paper, pressure–velocity cross-spectra using various linear mountain-wave solutions are shown to be capable of disentangling collocated waves with different propagation directions and wavelength. A field of group velocity vectors can also be determined.

In the second part, the energy flux wavelet technique is applied to five cases of mountain waves entering the stratosphere from the Terrain-Induced Rotor Experiment (T-REX) in 2006. Perturbation pressure along the flight track is determined using aircraft static pressure corrected hydrostatically with GPS altitude. In four of the cases, collocated long up-propagating and short down-propagating waves are seen in the stratosphere. These waves have strong, but opposite, p′w′ cospectra. In one of these cases, a patch of turbulence is collocated with the up and down waves. In two other cases, trapped waves riding on the tropopause inversion layer (TIL) are seen. These trapped waves have p′w′ quadrature spectra that reverse sign across the tropopause. These newly discovered wave types may arise from secondary wave generation (i.e., a nonlinear transfer of energy from the long vertically propagating waves to shorter modes).
Can Climate Models Capture the Structure of Extratropical Cyclones?
Authors: Catto Jennifer L. , Shaffrey Len C. , Hodges Kevin I.
Published: November 2009

Composites of wind speeds, equivalent potential temperature, mean sea level pressure, vertical velocity, and relative humidity have been produced for the 100 most intense extratropical cyclones in the Northern Hemisphere winter for the 40-yr ECMWF Re-Analysis (ERA-40) and the high resolution global environment model (HiGEM). Features of conceptual models of cyclone structure—the warm conveyor belt, cold conveyor belt, and dry intrusion—have been identified in the composites from ERA-40 and compared to HiGEM. Such features can be identified in the composite fields despite the smoothing that occurs in the compositing process. The surface features and the three-dimensional structure of the cyclones in HiGEM compare very well with those from ERA-40. The warm conveyor belt is identified in the temperature and wind fields as a mass of warm air undergoing moist isentropic uplift and is very similar in ERA-40 and HiGEM. The rate of ascent is lower in HiGEM, associated with a shallower slope of the moist isentropes in the warm sector. There are also differences in the relative humidity fields in the warm conveyor belt. In ERA-40, the high values of relative humidity are strongly associated with the moist isentropic uplift, whereas in HiGEM these are not so strongly associated. The cold conveyor belt is identified as rearward flowing air that undercuts the warm conveyor belt and produces a low-level jet, and is very similar in HiGEM and ERA-40. The dry intrusion is identified in the 500-hPa vertical velocity and relative humidity. The structure of the dry intrusion compares well between HiGEM and ERA-40 but the descent is weaker in HiGEM because of weaker along-isentrope flow behind the composite cyclone. HiGEM’s ability to represent the key features of extratropical cyclone structure can give confidence in future predictions from this model.
Coupling the ISBA Land Surface Model and the TOPMODEL Hydrological Model for Mediterranean Flash-Flood Forecasting: Description, Calibration, and Validation
Authors: Bouilloud Ludovic , Chancibault Katia , Vincendon Béatrice , Ducrocq Véronique , Habets Florence , Saulnier Georges-Marie , Anquetin Sandrine , Martin Eric , Noilhan Joel
Published: November 2009

Innovative coupling between the soil–vegetation–atmosphere transfer (SVAT) model Interactions between Soil, Biosphere, and Atmosphere (ISBA) and the hydrological model TOPMODEL has been specifically designed for flash-flood forecasting in the Mediterranean area. The coupled model described in this study combines the advantages of the two types of model: the accurate representation of water and energy transfer between the soil and the atmosphere within the SVAT column and an explicit representation of the lateral transfer of water over the hydrological catchment unit. Another advantage of this coupling is that the number of parameters to be calibrated is reduced by two, as only two parameters instead of four parameters concern the TOPMODEL formulation used here. The parameters to be calibrated concern only the water transfer. The model was calibrated for the simulation of flash-flood events on the three main watersheds covering the French Cévennes–Vivarais region using a subset of past flash-flood events having occurred since 2000. The complementary subset of flash-flood events was then used to carry out an objective verification of the coupled model after calibration. The evaluation on these six independent past flash-flood events shows satisfactory results. The comparison of the observed and simulated hydrographs demonstrates that no flash-flood peaks are missed. Relevant information for flash-flood forecasting can always be inferred from the simulations, even for those with quite poor results, making the system useful for real-time and operational flash-flood forecasting.
Satellite-Scale Snow Water Equivalent Assimilation into a High-Resolution Land Surface Model
Authors: De Lannoy Gabriëlle J. M. , Reichle Rolf H. , Houser Paul R. , Arsenault Kristi R. , Verhoest Niko E. C. , Pauwels Valentijn R. N.
Published: November 2009

Four methods based on the ensemble Kalman filter (EnKF) are tested to assimilate coarse-scale (25 km) snow water equivalent (SWE) observations (typical of passive microwave satellite retrievals) into finescale (1 km) land model simulations. Synthetic coarse-scale observations are assimilated directly using an observation operator for mapping between the coarse and fine scales or, alternatively, after disaggregation (regridding) to the finescale model resolution prior to data assimilation. In either case, observations are assimilated either simultaneously or independently for each location. Results indicate that assimilating disaggregated finescale observations independently (method 1D-F1) is less efficient than assimilating a collection of neighboring disaggregated observations (method 3D-Fm). Direct assimilation of coarse-scale observations is superior to a priori disaggregation. Independent assimilation of individual coarse-scale observations (method 3D-C1) can bring the overall mean analyzed field close to the truth, but does not necessarily improve estimates of the finescale structure. There is a clear benefit to simultaneously assimilating multiple coarse-scale observations (method 3D-Cm) even as the entire domain is observed, indicating that underlying spatial error correlations can be exploited to improve SWE estimates. Method 3D-Cm avoids artificial transitions at the coarse observation pixel boundaries and can reduce the RMSE by 60% when compared to the open loop in this study.
Conditional Nonlinear Optimal Perturbations: Adjoint-Free Calculation Method and Preliminary Test
Authors: Wang Bin , Tan Xiaowei
Published: November 2009

An ensemble-based approach is proposed to obtain conditional nonlinear optimal perturbation (CNOP), which is a natural extension of linear singular vector to a nonlinear regime. The new approach avoids the use of adjoint technique during maximization and is thus more attractive. Comparisons among CNOPs of a simple theoretical model generated by the ensemble-based, adjoint-based, and simplex-search methods, respectively, not only show potential equivalence of the first two approaches in application according to their very similar spatial structures and time evolutions of the CNOPs, but also reveal the limited performance of the third measure, an existing adjoint-free algorithm, due to its inconsistent spatial distribution and weak net growth ratio of norm square of CNOP comparing with the results of the first two methods. Because of its attractive features, the new approach is likely to make it easier to apply CNOP in predictability or sensitivity studies using operational prediction models.
Intercomparison of Variational Data Assimilation and the Ensemble Kalman Filter for Global Deterministic NWP. Part I: Description and Single-Observation Experiments
Authors: Buehner Mark , Houtekamer P. L. , Charette Cecilien , Mitchell Herschel L. , He Bin
Published: November 2009

An intercomparison of the Environment Canada variational and ensemble Kalman filter (EnKF) data assimilation systems is presented in the context of global deterministic NWP. In an EnKF experiment having the same spatial resolution as the inner loop in the four-dimensional variational data assimilation system (4D-Var), the mean of each analysis ensemble is used to initialize the higher-resolution deterministic forecasts. Five different variational data assimilation experiments are also conducted. These include both 4D-Var and 3D-Var (with first guess at appropriate time) experiments using either (i) prescribed background-error covariances similar to those used operationally, which are static in time and include horizontally homogeneous and isotropic correlations; or (ii) flow-dependent covariances computed from the EnKF background ensembles with spatial covariance localization applied. The fifth variational data assimilation experiment is a new approach called the Ensemble-4D-Var (En-4D-Var). This approach uses 4D flow-dependent background-error covariances estimated from EnKF ensembles to produce a 4D analysis without the need for tangent-linear or adjoint versions of the forecast model. In this first part of a two-part paper, results from a series of idealized assimilation experiments are presented. In these experiments, only a single observation or vertical profile of observations is assimilated to explore the impact of various fundamental differences among the EnKF and the various variational data assimilation approaches considered. In particular, differences in the application of covariance localization in the EnKF and variational approaches are shown to have a significant impact on the assimilation of satellite radiance observations. The results also demonstrate that 4D-Var and the EnKF can both produce similar 4D background-error covariances within a 6-h assimilation window. In the second part, results from medium-range deterministic forecasts for the study period of February 2007 are presented for the EnKF and the five variational data assimilation approaches considered.
India and the European Union
Authors: Sachdeva Gulshan
Published: November 2009

India and Europe share the vision of a democratic, multi-cultural and multi-polar world. In the recent past, trade and other economic ties have formed the core of India–EU partnership. Encouraged by positive trends, both have forged a strategic partnership and are negotiating for a broad-based bilateral trade and investment agreement. Despite many positive developments in the economic sphere, Indian policy makers are sceptical about Europe’s role as a major strategic player in Asia. Apart from economic issues, India’s partnership with the EU is still at a ‘dialogue’ level. The main challenge in the coming years will be to broaden the existing economic partnership to cover traditional and non-traditional security issues.
Coming into Money: The Impact of Foreign Aid on Leader Survival
Authors: Licht Amanda A.
Published: November 2009

Donors are more likely to send aid to leaders facing elevated risks of losing power, but targets’ ability to benefit from this assistance is conditioned by regime type and political processes. The institutionalization of winning coalitions’ loyalty across regime type follows opposite patterns, supporting opposite temporal dynamics across regime types. Democratic leaders’ coalitions are firmest immediately after taking office, and aid is of most assistance to them at that time. As competition and dissatisfaction grow, aid becomes a political liability. In small winning coalition systems, however, coalitions become more solid over time, facilitating increasing benefits from aid. Without a firm coalition, however, external resources are destabilizing to autocratic leaders. Analysis of 4,692 leader years from 1960 to 2001 using a censored probit model supports these expectations.
Intentional Control and Operational Constraints in Prosodic Phrasing: A Study of Picture-elicited Narrations by French Children
Authors: Vion Monique , Colas Annie
Published: November 2009

This study deals with the determinants of prosodic phrasing in French schoolchildren’s narratives. Children (aged 7 to 11) told picture stories to a silent same-age peer. The establishment of temporal and/or causal relations between the events was more or less guided by the drawings (ordered vs. arbitrary sequences). The comprehension of the referential links was more or less supported by the way the frames were displayed (simultaneous vs. consecutive display mode). Four storytelling conditions that differed by the constraints imposed on inference-resolving and memory-searching were thus defined.

Naïve French listeners were asked to segment tape-recorded narrations using prosodic variation as a criterion, and to decide whether each prosodic segment was “conclusive” or “continuative.” The comparison of the listeners’ segmentation labels to those of an expert (functional and formal annotation) showed that more than 91% of the labels corresponded to prosodic boundaries and more than 78% of the non-terminal labels corresponded to non-terminal boundaries, but only 55% of the terminal labels corresponded to terminal boundaries. The storytellers’ boundaries were then analyzed as a function of age and storytelling conditions. Non-terminal and terminal boundaries varied with the picture-display mode. Terminal boundaries also depended on the type of event sequence, and non-terminal boundaries on the improvement of the linguistic and communicative skills of the narrators. Terminal judgments of non-terminal boundaries mainly occurred in texts where each event was told in a single proposition either without anaphoric references to the main character or with anaphoric pronouns.
Violence, Weak Ontology, and Late-Modernity
Authors: White Stephen K.
Published: November 2009

This essay responds to the characterization Ted Miller offers (in his December 2008 essay in Political Theory) of the kind of nonfoundationalism I have referred to as “weak ontology,” and that Gianni Vattimo frequently calls “weak thought.” Miller argues that such a position embodies, first, a philosophy of history in which strong ontologies (e.g., religion) are assessed categorically as passé, and, second, are associated essentially with violence. I show that while these characterizations may be appropriate for Vattimo’s thought, they are not for weak ontology as I understand it. Finally, I suggest that the former might more usefully be categorized as “antifoundationalism” and the latter as “nonfoundationalism.”
Examining an Evolution: A Case Study of Organizational Change Accompanying the Community College Baccalaureate
Authors: McKinney Lyle , Morris Phillip A.
Published: November 2009

This study examined the nature and degree of organizational change that occurs when community colleges offer their own baccalaureate degree programs. Utilizing qualitative research methodology, we investigated how executive administrators at two Florida colleges managed this momentous change process and how this transformation has affected their colleges’ day-to-day operations. Our findings shed light on several important themes that emerged in interviews with the administrators: justifying the need for the degree, acquiring state approval and regional accreditation, modifying existing college policies and services, meeting challenges that are inherent in this transition, and developing strategies for leading this institutional transformation. Our goal was to provide a better understanding of this multifaceted organizational change process to help community college stakeholders make educated decisions regarding the introduction of 4-year degree programs at their institutions.
Chinese Constitutional Currents
Authors: White Lynn T.
Published: November 2009

The Chinese constitution in action is far more flexible than the written state charter might suggest. Jiang Shigong and Xueguang Zhou best capture China’s actual constitutional patterns of power, appointment, jurisdiction, and amendment when they treat China as complex, evolving, and large.
Responses of Young Adult Grandchildren to Grandparents’ Painful Self-Disclosures
Authors: Fowler Craig , Soliz Jordan
Published: November 2009

This study examined grandchildren’s relational and communicative responses to grandparents’ painful self-disclosures (PSDs). From the perspective of young adult grandchildren ( N = 297), discomfort with PSDs is more significant in differentiating positive and negative aspects of the grandparent—grandchild relationship than simply the occurrence of such disclosures. Furthermore, results reveal that the family communication environment and communicative responsiveness of the grandchild are important factors in predicting discomfort with PSDs as well as grandchildren’s communication with grandparents.
Some Problems in the Early Stages of Teaching Numbers to Language-Handicapped Children
Authors: Grauberg Eva
Published: November 2009

The paper deals with features of language-handicapped children which may lead to difficulties in understanding elementary number work. Six features are identified. Weakness in symbolic understanding is studied in relation to three aspects of the curriculum: understanding cardinality of numbers, the use of Hindu-Arabic figures, and the understanding of place value. An attempt is made to see problems from the child's perspective. Methodological suggestions for teaching are given, including the use of historic number systems as preparatory or intermediate steps, and the general adoption of a holistic approach.
What Does a Language Score Really Mean?
Authors: Müller Dave J.
Published: November 2009

This paper examines critically the use of psychometric tests as a means of assessing language-handicapped children. The nature of psychometric tests is described with reference to the way in which language scores are derived. The theoretical assumptions underlying psychometric measures of language are questioned, followed by a discussion of the difficulties which arise from interpreting language scores. The practical use of language scores is discussed and emphasis is given to how they might be incorporated into a scheme for working with language-handicapped children.
Developing Phonological Skills
Authors: Grunwell Pamela
Published: November 2009

Learning to pronounce is an integral part of the child's development of language. Children who experience difficulties learning language frequently exhibit pronunciation problems as well. This paper examines the nature of phonological development and the implications for helping language-handicapped children with phonological disorders.
CardioWest temporary total artificial heart
Authors: Platis Anthony , Larson Douglas F
Published: November 2009

Background: The CardioWest temporary total artificial heart (TAH-t) replaces both native ventricles of the heart and is more beneficial for a select group of patients than most other typical ventricular assist devices (VADs). This review will expand on the current literature and highlight the chronology of this device. The CardioWest TAH-t has been implanted in over 715 patients at 30 multiple institutional centers worldwide as a bridge-to-transplant (BTT) since 1993. The mechanical flow dynamics of the device are manufactured and designed differently from other traditional VADs, allowing increased outputs and normal filling pressures, allowing for sufficient organ and tissue perfusion and dramatic recoveries, allowing patients to return to an almost normal quality of life. Results: There was a 79% survival to transplant achievement in the protocol group who received the TAH-t versus a 46% in the control group (P < 0.001). Furthermore, there was a 70% survival rate at one year in the protocol group versus 31% in the control group (P < 0.001). The one- and five-year survival rates after transplantation were 69% and 34%, respectively, in the control group and 86% and 64%, respectively, in the protocol group. Conclusion: It is evident that the advancement of modern engineering and medicine has made way for a reliable and durable device that provides a promising future in the field of end-stage heart failure.