bluuebunny/crossref_metadata_2025 huggingface dataset:
Association Between the Coronary Artery Disease Risk Locus on Chromosome 9p21.3 and Abdominal Aortic Aneurysm
Authors: Bown Matthew J. , Braund Peter S. , Thompson John , London Nicholas J.M. , Samani Nilesh J. , Sayers Robert D.
Published: October 2008

Background—

Recent genome-wide studies have shown a significant association of a locus on chromosome 9p21.3 and coronary artery disease. We performed a case-control study to investigate the association between this locus and abdominal aortic aneurysm (AAA).

Methods and Results—

A total of 1714 patients (899 patients with AAA and 815 controls) were genotyped for the lead single-nucleotide polymorphism, rs1333049, on chromosome 9p21. The frequency of the C (risk) allele of rs1333049 in the control group was 0.471. There was a significant association between the C allele and AAA (odds ratio, 1.22; 95% confidence interval, 1.06 to 1.39;
P
=0.004). The genotypic-specific odds ratios (compared with the GG genotype) were 1.17 (95% confidence interval, 0.93 to 1.47;
P
=0.191) for the GC genotype and 1.50 (95% confidence interval, 1.14 to 1.97;
P
=0.004) for the CC genotype. In logistic regression modeling, the association of the CC genotype with AAA was independent of the presence of clinical coronary artery disease (odds ratio, 1.46; 95% confidence interval, 1.11 to 1.94;
P
=0.008).

Conclusions—

Our study shows that the recently identified chromosome 9 variant that increases risk of coronary artery disease is also associated with the presence of AAA. The findings suggest that the effect of this locus on risk of cardiovascular disease extends beyond the coronary circulation.
Complication Rate of Right Ventricular Endomyocardial Biopsy via the Femoral Approach
Authors: Holzmann Matthias , Nicko Alexander , Kühl Uwe , Noutsias Michel , Poller Wolfgang , Hoffmann Wolfgang , Morguet Andreas , Witzenbichler Bernhard , Tschöpe Carsten , Schultheiss Heinz-Peter , Pauschinger Matthias
Published: October 2008

Background—

An unequivocal diagnosis of myocarditis and cardiac virus persistence is based on histological, immunohistological, and molecular biological analyses of endomyocardial biopsies (EMBs). Biopsy-based diagnosis of myocarditis has become increasingly important because recent studies have demonstrated the beneficial effects of biopsy-based causal treatment strategies (immunosuppressive or antiviral). Because the risks of major complications caused by EMB procedures have not yet been well defined, we evaluated the incidence of major and minor complications of right ventricular EMB procedures in this retrospective and prospective single-center study.

Methods and Results—

With the use of a modified Cordis bioptome, 1919 patients underwent 2505 EMB procedures retrospectively over a 9-year period (January 1995 to December 2003), and 496 patients underwent 543 EMB procedures prospectively between January 2004 and December 2005. A total of 2415 patients had 3048 EMB procedures via the right femoral vein approach under biplane fluoroscopic control to evaluate unexplained left ventricular dysfunction (retrospective left ventricular ejection fraction, 49.8±18.8%; prospective, 48.8±19.7%) after exclusion of secondary causes. During each EMB procedure, an average of 8.2±0.8 EMBs were obtained retrospectively and 10.1±0.6 specimens prospectively for a total of 26 025 specimens. No patient died or required emergency cardiac surgery. Other major complications like cardiac tamponade requiring pericardiocentesis or complete atrioventricular block requiring permanent pacing were very rare: 0.12% in the retrospective study and 0% in the prospective study. Minor complications such as pericardial effusion, conduction abnormalities, or arrhythmias occurred in 0.20% of the EMB procedures in the retrospective study and 5.5% in the prospective study.

Conclusions—

The EMB procedure via the femoral vein approach under fluoroscopic guidance has a very low complication rate when performed by experienced operators.
Standards for Measures Used for Public Reporting of Efficiency in Health Care
Authors: Krumholz Harlan M. , Keenan Patricia S. , Brush John E. , Bufalino Vincent J. , Chernew Michael E. , Epstein Andrew J. , Heidenreich Paul A. , Ho Vivian , Masoudi Frederick A. , Matchar David B. , Normand Sharon-Lise T. , Rumsfeld John S. , Schuur Jeremiah D. , Smith Sidney C. , Spertus John A. , Walsh Mary Norine
Published: October 2008

The assessment of medical practice is evolving rapidly in the United States. An initial focus on structure and process performance measures assessing the quality of medical care is now being supplemented with efficiency measures to quantify the “value” of healthcare delivery. This statement, building on prior work that articulated standards for publicly reported outcomes measures, identifies preferred attributes for measures used to assess efficiency in the allocation of healthcare resources. The attributes identified in this document combined with the previously published standards are intended to serve as criteria for assessing the suitability of efficiency measures for public reporting. This statement identifies the following attributes to be considered for publicly reported efficiency measures: integration of the quality and cost; valid cost measurement and analysis; minimal incentive to provide poor quality care; and proper attribution of the measure. The attributes described in this statement are relevant to a wide range of efforts to profile the efficiency of various healthcare providers, including hospitals, healthcare systems, managed-care organizations, physicians, group practices, and others that deliver coordinated care.
Incomplete Inhibition of Thromboxane Biosynthesis by Acetylsalicylic Acid
Authors: Eikelboom John W. , Hankey Graeme J. , Thom Jim , Bhatt Deepak L. , Steg P. Gabriel , Montalescot Gilles , Johnston S. Claiborne , Steinhubl Steven R. , Mak Koon-Hou , Easton J. Donald , Hamm Christian , Hu Tingfei , Fox Keith A.A. , Topol Eric J.
Published: October 2008

Background—

Incomplete inhibition of platelet thromboxane generation, as measured by elevated urinary 11-dehydro thromboxane B
2
concentrations, has been associated with an increased risk of cardiovascular events. We aimed to determine the external validity of this association in aspirin-treated patients enrolled in the Clopidogrel for High Atherothrombotic Risk and Ischemic Stabilization, Management and Avoidance (CHARISMA) trial and to determine whether there are any modifiable factors or interventions that lower urinary 11-dehydro thromboxane B
2
concentrations that could thereby reduce cardiovascular risk.

Methods and Results—

Urinary 11-dehydro thromboxane B
2
concentrations were measured in 3261 aspirin-treated patients at least 1 month after they had been randomly assigned to placebo or clopidogrel. Baseline urinary 11-dehydro thromboxane B
2
concentrations in the highest quartile were associated with an increased risk of stroke, myocardial infarction, or cardiovascular death compared with the lowest quartile (adjusted hazard ratio 1.66, 95% CI 1.06 to 2.61,
P
=0.03). Increasing age, female sex, history of peripheral artery disease, current smoking, and oral hypoglycemic or angiotensin-converting enzyme inhibitor therapy were independently associated with higher urinary concentrations of 11-dehydro thromboxane B
2
, whereas aspirin dose ≥150 mg/d, history of treatment with nonsteroidal antiinflammatory drugs, history of hypercholesterolemia, and statin treatment were associated with lower concentrations. Randomization to clopidogrel (versus placebo) did not reduce the hazard of cardiovascular events in patients in the highest quartile of urinary 11-dehydro thromboxane B
2
levels.

Conclusions—

In aspirin-treated patients, urinary concentrations of 11-dehydro thromboxane B
2
are an externally valid and potentially modifiable determinant of stroke, myocardial infarction, or cardiovascular death in patients at risk for atherothrombotic events.
Fragmented QRS as a Marker of Conduction Abnormality and a Predictor of Prognosis of Brugada Syndrome
Authors: Morita Hiroshi , Kusano Kengo F. , Miura Daiji , Nagase Satoshi , Nakamura Kazufumi , Morita Shiho T. , Ohe Tohru , Zipes Douglas P. , Wu Jiashin
Published: October 2008

Background—

Conduction abnormalities serve as a substrate for ventricular fibrillation (VF) in patients with Brugada syndrome (BS). Signal-averaged electrograms can detect late potentials, but the significance of conduction abnormalities within the QRS complex is still unknown. The latter can present as multiple spikes within the QRS complex (fragmented QRS [f-QRS]). We hypothesized that f-QRS could indicate a substrate for VF and might predict a high risk of VF for patients with BS.

Methods and Results—

In study 1, we analyzed the incidence of f-QRS in 115 patients with BS (13 resuscitated from VF, 28 with syncope, and 74 asymptomatic). f-QRS was observed in 43% of patients, more often in the VF group (incidence of f-QRS: VF 85%, syncope 50%, and asymptomatic 34%,
P
<0.01).
SCN5A
mutations occurred more often in patients with f-QRS (33%) than in patients without f-QRS (5%). In patients with syncope or VF, only 6% without f-QRS experienced VF during follow-up (43±25 months), but 58% of patients with f-QRS had recurrent syncope due to VF (
P
<0.01). In study 2, to investigate the mechanism of f-QRS, we studied in vitro models of BS in canine right ventricular tissues (n=4) and optically mapped multisite action potentials. In the experimental model of BS, ST elevation resulted from a large phase 1 notch of the action potential in the epicardium, and local epicardial activation delay reproduced f-QRS in the transmural ECG.

Conclusions—

f-QRS appears to be a marker for the substrate for spontaneous VF in BS and predicts patients at high risk of syncope.
Local Tenomodulin Absence, Angiogenesis, and Matrix Metalloproteinase Activation Are Associated With the Rupture of the Chordae Tendineae Cordis
Authors: Kimura Naritaka , Shukunami Chisa , Hakuno Daihiko , Yoshioka Masatoyo , Miura Shigenori , Docheva Denitsa , Kimura Tokuhiro , Okada Yasunori , Matsumura Goki , Shin'oka Toshiharu , Yozu Ryohei , Kobayashi Junjiro , Ishibashi-Ueda Hatsue , Hiraki Yuji , Fukuda Keiichi
Published: October 2008

Background—

Rupture of the chordae tendineae cordis (CTC) is a well-known cause of mitral regurgitation. Despite its importance, the mechanisms by which the CTC is protected and the cause of its rupture remain unknown. CTC is an avascular tissue. We investigated the molecular mechanisms underlying the avascularity of CTC and the correlation between avascularity and CTC rupture.

Methods and Results—

We found that tenomodulin, which is a recently isolated antiangiogenic factor, was expressed abundantly in the elastin-rich subendothelial outer layer of normal rodent, porcine, canine, and human CTC. Conditioned medium from cultured CTC interstitial cells strongly inhibited tube formation and mobilization of endothelial cells; these effects were partially inhibited by small-interfering RNA against tenomodulin. The immunohistochemical analysis was performed on 12 normal and 16 ruptured CTC obtained from the autopsy or surgical specimen. Interestingly, tenomodulin was locally absent in the ruptured areas of CTC, where abnormal vessel formation, strong expression of vascular endothelial growth factor-A and matrix metalloproteinases, and infiltration of inflammatory cells were observed, but not in the normal or nonruptured area. In anesthetized open-chest dogs, the tenomodulin layer of tricuspid CTC was surgically filed, and immunohistological analysis was performed after several months. This intervention gradually caused angiogenesis and expression of vascular endothelial growth factor-A and matrix metalloproteinases in the core collagen layer in a time-dependent manner.

Conclusions—

These findings provide evidence that tenomodulin is expressed universally in normal CTC in a concentric pattern and that local absence of tenomodulin, angiogenesis, and matrix metalloproteinase activation are associated with CTC rupture.
AMP Activated Protein Kinase-α2 Deficiency Exacerbates Pressure-Overload–Induced Left Ventricular Hypertrophy and Dysfunction in Mice
Authors: Zhang Ping , Hu Xinli , Xu Xin , Fassett John , Zhu Guangshuo , Viollet Benoit , Xu Wayne , Wiczer Brian , Bernlohr David A. , Bache Robert J. , Chen Yingjie
Published: October 2008

AMP activated protein kinase (AMPK) plays an important role in regulating myocardial metabolism and protein synthesis. Activation of AMPK attenuates hypertrophy in cultured cardiac myocytes, but the role of AMPK in regulating the development of myocardial hypertrophy in response to chronic pressure overload is not known. To test the hypothesis that AMPKα2 protects the heart against systolic overload–induced ventricular hypertrophy and dysfunction, we studied the response of AMPKα2 gene deficient (knockout [KO]) mice and wild-type mice subjected to 3 weeks of transverse aortic constriction (TAC). Although AMPKα2 KO had no effect on ventricular structure or function under control conditions, AMPKα2 KO significantly increased TAC-induced ventricular hypertrophy (ventricular mass increased 46% in wild-type mice compared with 65% in KO mice) while decreased left ventricular ejection fraction (ejection fraction decreased 14% in wild-type mice compared with a 43% decrease in KO mice). AMPKα2 KO also significantly exacerbated the TAC-induced increases of atrial natriuretic peptide, myocardial fibrosis, and cardiac myocyte size. AMPKα2 KO had no effect on total S6 ribosomal protein (S6), p70 S6 kinase, eukaryotic initiation factor 4E, and 4E binding protein-1 or their phosphorylation under basal conditions but significantly augmented the TAC-induced increases of p-p70 S6 kinase
Thr389
, p-S6
Ser235
, and p-eukaryotic initiation factor 4E
Ser209
. AMPKα2 KO also enhanced the TAC-induced increase of p-4E binding protein-1
Thr46
to a small degree and augmented the TAC-induced increase of p-Akt
Ser473
. These data indicate that AMPKα2 exerts a cardiac protective effect against pressure-overload–induced ventricular hypertrophy and dysfunction.
ADMA Impairs Nitric Oxide–Mediated Arteriolar Function Due to Increased Superoxide Production by Angiotensin II–NAD(P)H Oxidase Pathway
Authors: Veresh Zoltan , Racz Anita , Lotz Gabor , Koller Akos
Published: October 2008

Asymmetrical dimethylarginine (ADMA) is thought to be an endogenous regulator of arteriolar tone by inhibiting NO synthase. However, our previous studies showed that, in isolated arterioles, ADMA induced superoxide production as well. Thus, the mechanisms by which ADMA affects arteriolar tone remain obscure. We hypothesized that ADMA, by activating NAD(P)H oxidase, increases superoxide production, interfering with NO mediation of flow-induced dilation. In the presence of indomethacin, isolated arterioles from rat gracilis muscle (≈160 μm at 80 mm Hg) were incubated with ADMA (10
−4
mol/L), which elicited significant constriction (from 162±4 to 143±4 μm) and eliminated the dilations to increases in intraluminal flow (from a maximum 31±2% to 3±1%;
P
<0.05). In the presence of ADMA, superoxide dismutase plus catalase restored dilations to flow (from a maximum 3±1% to 28±2%). Endothelial denudation or incubation of arterioles with the NAD(P)H oxidase inhibitor apocynin or the angiotensin-converting enzyme inhibitor quinapril inhibited ADMA-induced constriction. In addition, apocynin, quinapril, or the angiotensin type 1 receptor blocker losartan restored flow-induced dilations reduced by ADMA. Furthermore, inhibition of NO synthase abolished the “superoxide dismutase/catalase-restored” flow-induced dilation in the presence of ADMA. ADMA-induced increased production of superoxide, assessed by dihydroethidium fluorescence, was inhibited by apocynin, quinapril, or losartan. We suggest that ADMA activates the local renin-angiotensin system, and the angiotensin II released activates NAD(P)H oxidase; superoxide produced interferes with the bioavailability of NO, resulting in diminished flow-induced dilation, a mechanism that may contribute to the development of arteriolar dysfunction and increased tone associated with elevated ADMA levels.
Blood Pressure Associated With Sleep-Disordered Breathing in a Population Sample of Children
Authors: Bixler Edward O. , Vgontzas Alexandros N. , Lin Hung-Mo , Liao Duanping , Calhoun Susan , Fedok Fred , Vlasic Vukmir , Graff Gavin
Published: October 2008

The current criteria for sleep-disordered breathing (SDB) in children are not based on a clinically relevant outcome. The purpose of this study was to assess the association of blood pressure with SDB in a random sample of the local elementary school children (kindergarten through grade 5) using a 2-phased strategy. During phase 1, a brief questionnaire was completed for all of the children (N=5740) with a response rate of 78.5%. During phase 2, 700 randomly selected children from phase 1 with a response rate of 70.0% were assessed with a full polysomnograph and a history/physical, including an ECG; ear, nose, and throat; and pulmonary evaluation. We observed a significantly elevated systolic blood pressure associated with the apnea hypopnea index (AHI): AHI ≥1 (2.9 mm Hg); AHI ≥3 (7.1 mm Hg); and AHI ≥5 (12.9 mm Hg). The SDB and blood pressure association remained significant after adjusting for age, sex, race, body mass index percentile or waist circumference, sleep efficiency, percentage of rapid eye movement sleep, and snoring. In addition, older age, body mass index percentile, waist circumference, and snoring were significantly associated with blood pressure, independent of SDB. Based on these findings, our study suggests that SDB is significantly associated with higher levels of systolic blood pressure in children aged 5 to 12 years even after adjusting for the various confounding factors. Clinically, the data support the threshold of AHI ≥5 for the initiation of treatment for SDB. Additional research is indicated to assess the efficacy of SDB treatment on reducing blood pressure.
Plasma 25-Hydroxyvitamin D Levels and Risk of Incident Hypertension Among Young Women
Authors: Forman John P. , Curhan Gary C. , Taylor Eric N.
Published: October 2008

Numerous cross-sectional studies demonstrate an inverse association between plasma 25-hydroxyvitamin D [25(OH)D] and blood pressure or hypertension. Prospective data, however, are limited. Among 1484 women aged 32 to 52 years who did not have hypertension at baseline, we prospectively analyzed the association between plasma levels of 25(OH)D and the odds of incident hypertension using a nested case-control study design. We matched cases and controls on age, race, and month of blood collection and further adjusted for body mass index, physical activity, family history of hypertension, oral contraceptive use, and plasma levels of parathyroid hormone, calcium, phosphorous, creatinine, and uric acid. Median plasma 25(OH)D levels were lower in the cases (25.6 ng/mL) than in the controls (27.3 ng/mL;
P
<0.001). Women in the lowest compared with highest quartile of plasma 25(OH)D had an adjusted odds ratio for incident hypertension of 1.66 (95% CI: 1.11 to 2.48;
P
for trend=0.01). Compared with women with sufficient levels, those with vitamin D deficiency (<30 ng/mL; 65.7% of the study population) had a multivariable odds ratio of 1.47 (95% CI: 1.10 to 1.97). Plasma 25(OH)D levels are inversely and independently associated with the risk of developing hypertension.
Case-Marking Strategies
Authors: de Hoop Helen , Malchukov Andrej L.
Published: October 2008

Two strategies of case marking in natural languages are discussed. These are defined as two violable constraints whose effects are shown to converge in the case of differential object marking but diverge in the case of differential subject marking. The discourse prominence of the case-bearing arguments is shown to be of utmost importance for case-marking and voice alternations. The analysis of the case-marking patterns that are found crosslinguistically is couched in a bidirectional Optimality Theory analysis.
On the Nature of the Antiagreement Effect: Evidence from Wh-in-Situ in Ibibio
Authors: Baker Mark C.
Published: October 2008

The Ibibio language displays an antiagreement effect (AAE), in which φ-feature agreement on the verb is suppressed in subject questions, even when the wh-phrase remains in situ. I discuss why this fact is problematic for existing theories of the AAE. I then suggest that the AAE arises when the deletion process that applies to copies in a movement chain removes the φ-features of a copy along with its semantic features. This formulation applies equally well to overt and covert wh-movement. It also generalizes to explain why quantified subjects do not trigger an AAE in Ibibio, whereas subjects in negative clauses do.
An Argument against Assimilating Appositive Relatives to Coordinate Structures
Authors: Citko Barbara
Published: October 2008

This article offers a critical examination of De Vries's (2006) account of appositive relatives, which treats appositive relatives and nominal appositions alike and assimilates both to coordinate structures. Its main focus is on the following properties of appositive relatives: (a) the category of the appositive head, (b) the case of the appositive head, (c) relative pronoun selection, (d) extraction phenomena, (e) the typology of specifying coordinators, and (f) the lack of prenominal appositives. It examines these properties from both an empirical and a theoretical perspective, contrasting De Vries's account with a version of an adjunction account.
The Temperature Paradox and Temporal Interpretation
Authors: Romero Maribel
Published: October 2008

Montague's analysis of the well-known temperature paradox poses a problem for Gupta's syllogism, whose surface syntax differs from that of the temperature syllogism by the addition of the intensional adverb necessarily. Lasersohn (2005) argues that the puzzle arising from these syllogisms can be solved if one adopts the Fregean presuppositional treatment of definite descriptions, and he concludes that the temperature-Gupta puzzle provides an argument in favor of such treatment. This article shows that the analysis of definite descriptions is in fact orthogonal to the puzzle. Instead, the differences between the two syllogisms turn out to stem from the temporal interpretation of their premises.
Evaluation of the Simple Urban Energy Balance Model Using Selected Data from 1-yr Flux Observations at Two Cities
Authors: Kawai Toru , Ridwan Mohammad Kholid , Kanda Manabu
Published: October 2008

The authors’ objective was to apply the Simple Urban Energy Balance Model for Mesoscale Simulation (SUMM) to cities. Data were selected from 1-yr flux observations conducted at three sites in two cities: one site in Kugahara, Japan (Ku), and two sites in Basel, Switzerland (U1 and U2). A simple vegetation scheme was implemented in SUMM to apply the model to vegetated cities, and the surface energy balance and radiative temperature TR were evaluated. SUMM generally reproduced seasonal and diurnal trends of surface energy balance and TR at Ku and U2, whereas relatively large errors were obtained for the daytime results of sensible heat flux QH and heat storage ΔQS at U1. Overall, daytime underestimations of QH and overestimations of ΔQS and TR were common. These errors were partly induced by the poor parameterization of the natural logarithm of the ratio of roughness length for momentum to heat (κB−1); that is, the observed κB−1 values at vegetated cities were smaller than the simulated values. The authors proposed a new equation for predicting this coefficient. This equation accounts for the existence of vegetation and improves the common errors described above. With the modified formula for κB−1, simulated net all-wave radiation and TR agreed well with observed values, regardless of site and season. However, at U1, simulated QH and ΔQS were still overestimated and underestimated, respectively, relative to observed values.
Formation of Jets and Equatorial Superrotation on Jupiter
Authors: Schneider Tapio , Liu Junjun
Published: October 2008

The zonal flow in Jupiter’s upper troposphere is organized into alternating retrograde and prograde jets, with a prograde (superrotating) jet at the equator. Existing models posit as the driver of the flow either differential radiative heating of the atmosphere or intrinsic heat fluxes emanating from the deep interior; however, they do not reproduce all large-scale features of Jupiter’s jets and thermal structure. Here it is shown that the difficulties in accounting for Jupiter’s jets and thermal structure resolve if the effects of differential radiative heating and intrinsic heat fluxes are considered together, and if upper-tropospheric dynamics are linked to a magnetohydrodynamic (MHD) drag that acts deep in the atmosphere and affects the zonal flow away from but not near the equator. Baroclinic eddies generated by differential radiative heating can account for the off-equatorial jets; meridionally propagating equatorial Rossby waves generated by intrinsic convective heat fluxes can account for the equatorial superrotation. The zonal flow extends deeply into the atmosphere, with its speed changing with depth, away from the equator up to depths at which the MHD drag acts. The theory is supported by simulations with an energetically consistent general circulation model of Jupiter’s outer atmosphere. A simulation that incorporates differential radiative heating and intrinsic heat fluxes reproduces Jupiter’s observed jets and thermal structure and makes testable predictions about as yet unobserved aspects thereof. A control simulation that incorporates only differential radiative heating but not intrinsic heat fluxes produces off-equatorial jets but no equatorial superrotation; another control simulation that incorporates only intrinsic heat fluxes but not differential radiative heating produces equatorial superrotation but no off-equatorial jets. The proposed mechanisms for the formation of jets and equatorial superrotation likely act in the atmospheres of all giant planets.
Dynamics of the West African Monsoon. Part IV: Analysis of 25–90-Day Variability of Convection and the Role of the Indian Monsoon
Authors: Janicot Serge , Mounier Flore , Hall Nicholas M. J. , Leroux Stéphanie , Sultan Benjamin , Kiladis George N.
Published: October 2008

This paper is part of a series of studies addressing the dynamics of the West African summer monsoon at intraseasonal time scales between 10 and 90 days. The dominant mode of 25–90-day convective variability in the African monsoon was investigated, starting from previous results involving the excitation of dry equatorial Kelvin and Rossby waves by a negative diabatic heat source located over the warm pool. This evolution is consistent with a significant contribution by a convectively coupled equatorial Rossby wave and the MJO. On the other hand, convectively coupled Kelvin waves as well as the dry Kelvin wave signal have a very weak impact. However, there is more to the global control of the African summer monsoon than convectively coupled wave dynamics. The active/break cycle of the Indian monsoon, controlled by a northward-moving dipole of diabatic heating in the Indian sector, can also influence the African monsoon through atmospheric teleconnections. Simulations performed with a dry primitive equation model show that this influence may be transferred through the northern Indian heat source, which excites a Rossby cyclonic circulation propagating westward over North Africa that is cut off by the northward arrival of the equatorial Indian heat source and the associated intrusion of an anticyclonic ridge. Low-level westerly winds and moisture advection within the ITCZ consequently increase over Africa. The mean time lag between an active phase over India and over Africa is about 15–20 days.
Effective Eddy Diffusivities Inferred from a Point Release Tracer in an Eddy-Resolving Ocean Model
Authors: Lee Mei-Man , Nurser A. J. George , Coward Andrew C. , de Cuevas Beverly A.
Published: October 2008

This study uses tracer experiments in a global eddy-resolving ocean model to examine two diagnostic methods for inferring effective eddy isopycnic diffusivity from point release tracers. The first method is based on the growth rate of the area occupied by the tracers (the equivalent variance). During the period when tracer dispersion is dominated by stirring, the equivalent variance is found to increase at a rate between the second power law (for a pure shearing flow regime) and the exponential law (for a pure stretching flow regime). The second method is based on the length of the tracer contours. In the framework of equivalent radius, the two methods of inferring eddy diffusivity can be understood as two different averagings over the tracer patch. Over a shorter period of tracer dispersion the two methods give different eddy diffusivities, and only over a longer time when tracer dispersion approaches the final stage of diffusion do they give a similar value of diffusivity. A new diagnostic quantity called stirring efficiency is introduced to indicate different flow regimes by measuring the efficiency of stirring against mixing. The new diagnostic quantity has the advantage that it can be calculated directly from the gradients of tracer distribution without needing to estimate strain rate or background diffusivity.
Wave-Driven Circulation of a Coastal Reef–Lagoon System
Authors: Lowe Ryan J. , Falter James L. , Monismith Stephen G. , Atkinson Marlin J.
Published: October 2008

The response of the circulation of a coral reef system in Kaneohe Bay, Hawaii, to incident wave forcing was investigated using field data collected during a 10-month experiment. Results from the study revealed that wave forcing was the dominant mechanism driving the circulation over much of Kaneohe Bay. As predicted theoretically, wave setup generated near the reef crest resulting from wave breaking established a pressure gradient that drove flow over the reef and out of the two reef channels. Maximum reef setup was found to be roughly proportional to the offshore wave energy flux above a threshold root-mean-square wave height of 0.7 m (at which height setup was negligible). On the reef flat, the wave-driven currents increased approximately linearly with incident wave height; however, the magnitude of these currents was relatively weak (typically <20 cm s−1) because of (i) the mild fore-reef slope of Kaneohe Bay that reduced setup resulting from a combination of frictional wave damping and its relatively wide surf zone compared to steep-faced reefs, and (ii) the presence of significant wave setup inside its coastally bounded lagoon, resulting from frictional resistance on the lagoon–channel return flows, which reduced cross-reef setup gradients by 60%–80%. In general, the dynamics of these wave-driven currents roughly matched predictions derived from quasi-one-dimensional mass and momentum balances that incorporated radiation stresses, setup gradients, bottom friction, and the morphological properties of the reef–lagoon system.
Objective Classification of Precipitating Convective Regimes Using a Weather Radar in Darwin, Australia
Authors: Caine Simon , Jakob Christian , Siems Steven , May Peter
Published: October 2008

A clustering algorithm was applied to Frequency with Altitude Diagrams (FADs) derived from 4 yr of hourly radar data to objectively define four tropical precipitation regimes that occur during the wet season over Darwin Australia. The precipitation regimes defined are distinguished in terms of convective intensity, presence of stratiform precipitation, and precipitation coverage. Regime 1 consists of patchy convection of medium intensity and low area coverage, and regime 2 contains strong convection with relatively small area coverage. Regime 3 is composed of weak convection with large area coverage and large stratiform regions, and regime 4 contains strong convection with large area coverage and large stratiform regions. Analysis of the seasonal cycle, diurnal cycle, and regime occurrence as a function of monsoon activity all provide insight into the different physical character of the precipitation regimes. Two of the regimes exhibit a diurnal cycle with a peak in the afternoon, while the other two show a peak in their frequency of occurrence in the early morning. The different character of the regimes is also confirmed by the varying contributions that convective and stratiform rainfall make to the overall within-regime precipitation.
Four-Dimensional Variational Data Assimilation for WRF: Formulation and Preliminary Results
Authors: Huang Xiang-Yu , Xiao Qingnong , Barker Dale M. , Zhang Xin , Michalakes John , Huang Wei , Henderson Tom , Bray John , Chen Yongsheng , Ma Zaizhong , Dudhia Jimy , Guo Yongrun , Zhang Xiaoyan , Won Duk-Jin , Lin Hui-Chuan , Kuo Ying-Hwa
Published: October 2008

The Weather Research and Forecasting (WRF) model–based variational data assimilation system (WRF-Var) has been extended from three- to four-dimensional variational data assimilation (WRF 4D-Var) to meet the increasing demand for improving initial model states in multiscale numerical simulations and forecasts. The initial goals of this development include operational applications and support to the research community. The formulation of WRF 4D-Var is described in this paper. WRF 4D-Var uses the WRF model as a constraint to impose a dynamic balance on the assimilation. It is shown to implicitly evolve the background error covariance and to produce the flow-dependent nature of the analysis increments. Preliminary results from real-data 4D-Var experiments in a quasi-operational setting are presented and the potential of WRF 4D-Var in research and operational applications are demonstrated. A wider distribution of the system to the research community will further develop its capabilities and to encourage testing under different weather conditions and model configurations.
Characteristics of Vertical Velocity Cores in Different Convective Systems Observed over Gadanki, India
Authors: Uma K. N. , Rao T. Narayana
Published: October 2008

The Indian mesosphere–stratosphere–troposphere (MST) radar measurements during the passage of 60 convective systems are used to study the vertical air velocity (w) characteristics of tropical convection. The up- and downdraft cores and various stages/types of convection (shallow, deep, and decaying) are discerned from radar time–intensity maps of w. The characteristics of cores (speed, size, orientation, vertical extent, gravity wave activity, etc.) at different stages of convection are discussed with the help of three case studies. The cores stratified based on the type of convection are mostly erect in nature in all types of convective systems, except for deep updraft cores. A considerable percentage (35%) of deep updraft cores show inclined structure with elevation angles as low as 0°–20°. The variation of the horizontal wind field with height and the internal dynamics of mesoscale convective systems (MCSs) are thought to be responsible for this geometry. Further, the vertical extent of draft cores is limited in all types of convection, except for deep updraft cores. About 77% of deep updraft cores have a vertical extent greater than 10 km and ∼23% of these cores reach an altitude of 16 km. The size (overpass time) of the core shows an increasing trend with altitude up to 10–12 km and then decreases. Among different types of convection, the size of core is larger for deep updraft cores and smaller for shallow updraft cores. The variation of w distribution with height is different for different convection categories. The mode (and also the mean) of the distribution shows low-level descent (below 3 km) and mid–high-level ascent in shallow and deep convection categories, while nearly uniform distribution is seen in decaying convection. Strong updrafts are seen in deep convective systems in the upper troposphere (of the order of 15–20 m s−1), followed by shallow and decaying systems, while downdrafts are generally weaker in all types of convection. The variability (within the cores and also with altitude) and the number of data points are larger in updraft cores than in downdraft cores corresponding to shallow and deep convection. Contrasting the composite w profile at Gadanki with those obtained elsewhere revealed interesting features: the absence of subsidence at higher levels, the presence of low-level subsidence, a single ascent peak in the middle troposphere, etc. Further, the magnitude of composite w derived from wind profiler measurements is larger than that obtained with other techniques.
Permittivity Characteristics in the X- and S-Band Frequencies of Microwave Absorbers Based on Rubber Ferrite Composites
Authors: Prema K.H. , Kurian Philip , Anantharaman M.R. , Suma M.N. , Joseph Manoj
Published: October 2008

Fine particles of nickel ferrite are synthesized by the sol-gel technique and characterized by the X-ray diffraction method. These materials are incorporated in ethylene propylene diene rubber (EPDM) according to a specific recipe for various loadings. The rubber ferrite composites (RFCs) thus obtained have several applications, such as microwave absorbers, EMI shielding materials, etc. In the present study, microwave attenuation and dielectric properties of RFCs are studied in the X- and S-band frequencies. Real and imaginary parts of the dielectric permittivity are determined by cavity perturbation method. Dielectric permittivity in X-band frequency, based on Maxwell—Garnet equation is calculated and presented here.
Effect of Bagasse on the Physico-mechanical Properties of Natural and Styrene-Butadiene Rubbers
Authors: Abdelwahab N.A. , Helaly F.M. , Badran A.S.
Published: October 2008

Different concentrations of bagasse waste with particle sizes 300 nm, 125 nm, 75 nm, and <75nm are incorporated in natural and styrene-butadiene rubber formulations. The rheological characteristics and physico-mechanical properties of the compounded rubber are investigated and determined. The effect of bagasse upon ageing characteristics of corresponding vulcanizates is evaluated. The rubber vulcanizates containing the smallest particle size of bagasse with concentration 30phr showed the best retained values of physico-mechanical properties and equilibrium swelling in comparison with those of conventional fillers (Hisil, calcium carbonate, and High Abrasion Furance carbon black) used in industry. The bagasse with particle size 300 nm and concentration 70 phr showed the least retained values of physico-mechanical properties and equilibrium swelling in comparison with the other investigated particle sizes.
Hydrosilylation of Impact Polypropylene Co-polymer in a Twin-screw Extruder
Authors: Bulsari Mercy P. , Tzoganakis Costas , Penlidis Alexander
Published: October 2008

The production of hydrosilylated impact polypropylene (PP) copolymer has been demonstrated in a co-rotating twin-screw extruder. This has been accomplished through a two-step reactive extrusion process that involves: (i) the formation of terminal double bonds on a commodity PP copolymer through peroxide initiated degradation reactions, and (ii) the melt-phase functionalization of these double bonds with hydride-terminated polydimethylsiloxane (PDMS). Spectroscopic analysis of the peroxide degraded PP and the purified hydrosilylated PP has been performed to confirm the attachment of PDMS onto the PP chains. In addition, the hydrosilylated PP has been characterized in terms of molecular, rheological, surface, and mechanical properties. It has been found that the two-step hydrosilylation reaction decreases molecular weight, imparts formation of branching/chain extension, decreases impact strength, and improves surface hydrophobicity. Finally, oscillatory shear measurements exhibit an unusual up-turn in the viscosity curve at low frequencies.
The Burroughs Wellcome Career Award in the Biomedical Sciences
Authors: Pion Georgine M. , Cordray David S.
Published: October 2008

The Career Award in Biomedical Sciences (CABS) was launched by the Burroughs Wellcome Fund to assist talented scientists to cross the “bridge” that connects postdoctoral training with independent investigator status. This study examines the causal effects of CABS, using both conventional methods and a newer method (propensity score analysis) in attempting to account for selection biases (e.g., selecting the “best and the brightest”) in estimating the award's impact. The results indicated that grantees outperformed unsuccessful applicants in obtaining a faculty position, competing for an R01 grant, and publishing in prestigious journals. However, it was nearly impossible to remove all the effects of selection bias from estimates of program effects. Because selection bias is a pervasive problem in assessing these programs, recommendations for improving evaluations of similar merit-based programs are offered.
How is sleep quality affected by the psychological and symptom distress of advanced cancer patients?
Authors: Mystakidou K , Parpa E , Tsilika E , Gennatas C , Galanos A , Vlahos L
Published: October 2008

The aim of this study was to assess the relationship between sleep quality, pain, psychological distress, cognitive status and post-traumatic experience in advanced cancer patients. Participants were 82 advanced cancer patients referred to a palliative care unit for control of pain and other symptoms. A variety of assessment tools were used to examine the prevalence of sleep disturbance, the severity of pain and depression, hopelessness, cognitive function and quality of life. Using the Pittsburgh Sleep Quality Index (PSQI) 96% of patients were ‘poor sleepers’. Statistically significant associations were found between PSQI and the SF-12 (Short Form-12) Quality of Life Instrument (MCS, P < 0.0005, PCS, P < 0.0005), depression (Greek Depression Inventory) ( P < 0.0005) and hopelessness (Beck Hopelessness Scale) ( P = 0.003). Strong associations were also found between PSQI and IES-R (Impact of Event Scale-Revised) ( P = 0.004). The strongest predictors of poor sleep quality in this model were MCS ( P < 0.0005), PCS ( P < 0.0005) and IES-R ( P = 0.010). Post-traumatic experience and quality of life seemed to be the strongest predictors of sleep quality in a sample of advanced cancer patients referred for palliative care.
Low-dose quetiapine for patients with dysregulation of hyperthymic and cyclothymic temperaments
Authors: Bisol Luísa W , Lara Diogo R
Published: October 2008

Patients with hyperthymic and cyclothymic temperaments often develop symptoms that fail to meet diagnostic criteria for bipolar disorders. These patients can be conceived as having bipolar disorder NOS (not otherwise specified), a bipolar spectrum disorder, cyclothymic disorder or cluster B personality traits. Here, we describe four of these patients with mild to moderate symptoms affecting mood, behaviour, emotional reactivity and sleep. Treatment with low-dose quetiapine (25—75 mg/day at night) lead to sustained symptom remission. Two of them were on quetiapine monotherapy. Such low doses occupy a minority of D2 and 5-HT2 receptors, which may nevertheless be of therapeutic value in mild cases. Alternatively, other mechanisms more likely to occur at low doses, such as antagonism of H1, α(1B)-adrenergic and other serotonin receptors, as well as reduction cortisol secretion, may be involved in the therapeutic efficacy of quetiapine.
Tolerance to the cataleptic effect that follows repeated nitric oxide synthase inhibition may be related to functional enzymatic recovery
Authors: Del-Bel EA , Guimarães FS , Joca SRL , Echeverry MB , Ferreira FR
Published: October 2008

Systemic or intra-striatal acute administration of nitric oxide synthase (NOS) inhibitors causes catalepsy in rodents. This effect disappears after sub-chronic treatment. The aim of the present study was to investigate if this tolerance is related to changes in the expression of NOS or dopamine-2 (D2) receptor or to a recovery of NOS activity. Male albino Swiss mice (25—30 g) received single or sub-chronic (once a day for 4 days) i.p. injections of saline or L-nitro-arginine (L-NOARG, 40 mg/kg), a non-selective inhibitor of neuronal nitric oxide synthase (nNOS). Twenty-four hours after the last injection, the animals were killed and their brains were removed for immunohistochemistry assay to detect the presence of nNOS or for ‘in-situ’ hybridisation study using 35S-labeled oligonucleotide probe complementary to D2 receptor mRNA. The results were analysed by computerised densitometry. Independent groups of animals received the same treatment, but were submitted to the catalepsy test and had their brain removed to measure nitrite and nitrate (NOx) concentrations in the striatum. Acute administration of L-NOARG caused catalepsy that disappeared after sub-chronic treatment. The levels of NOx were significantly reduced after acute L-NOARG treatment. The decrease in NOx after drug injection suffered a partial tolerance after sub-chronic treatment. The catalepsy time after acute or sub-chronic treatment with L-NOARG was negatively (r = −0.717) correlated with NOx levels. Animals that received repeated L-NOARG injections also showed an increase in the number of nNOS-positive neurons in the striatum. No change in D2 receptor mRNA expression was found in the dorsal striatum, nucleus accumbens and substantia nigra. Together, these results suggest that tolerance to L-NOARG cataleptic effects do not depend on changes in D2 receptors. They may depend, however, on plastic changes in nNOS neurons resulting in partial recovery of NO formation in the striatum.
A neurotensin agonist and antagonist decrease and increase activity, respectively, but do not preclude discrete cue conditioning
Authors: Norman C. , Grimond-Billa SK , Bennett GW , Cassaday HJ
Published: October 2008

There is evidence to suggest that neurotensin (NT) may enhance cognitive function. For example, in aversive trace conditioning, the NT agonist PD149163 selectively increased trace conditioning (Grimond-Billa, et al., 2008). The present study, therefore, examined the role of NT in associative learning, tested using an appetitive trace conditioning procedure (0-s or 10-s inter-stimulus-interval [ISI]) with a mixed frequency noise as a conditioned stimulus (CS) and food delivery as the unconditioned stimulus (UCS). The effects of an NT agonist (PD149163, 0.125 and 0.25 mg/kg, Experiment 1) and an NT antagonist (SR142948A, 0.01 and 0.1 mg/kg, Experiment 2) were compared. To take nonspecific effects of these compounds into account, conditioning to the CS was measured as a percentage of total responding, during UCS deliveries and in the inter-trial-interval (ITI). In both experiments, associative learning to the contiguously (0-s) presented CS was demonstrated, although there was a relative reduction in this learning under 0.125 mg/kg PD149163. Counter to prediction, the only effect on trace conditioning was some overall reduction in responding to the CS in the 10-s group conditioned under 0.25 mg/kg PD149163. The NT antagonist was without any effect on appetitive conditioning. However, these NT compounds were not ineffective: decreases and increases in responding in the ITI, ISI and during UCS deliveries seen under PD149163 and SR142948A were dissociable from effects on discrete cue conditioning.