bluuebunny/crossref_metadata_2025 huggingface dataset:
Storing semi-structured data on disk drives
Authors: Bhadkamkar Medha , Farfan Fernando , Hristidis Vagelis , Rangaswami Raju
Published: June 2009

Applications that manage semi-structured data are becoming increasingly commonplace. Current approaches for storing semi-structured data use existing storage machinery; they either map the data to relational databases, or use a combination of flat files and indexes. While employing these existing storage mechanisms provides readily available solutions, there is a need to more closely examine their suitability to this class of data. Particularly, retrofitting existing solutions for semi-structured data can result in a mismatch between the tree structure of the data and the access characteristics of the underlying storage device (disk drive). This study explores various possibilities in the design space of native storage solutions for semi-structured data by exploring alternative approaches that match application data access characteristics to those of the underlying disk drive. For evaluating the effectiveness of the proposed native techniques in relation to the existing solution, we experiment with XML data using the XPathMark benchmark. Extensive evaluation reveals the strengths and weaknesses of the proposed native data layout techniques. While the existing solutions work really well for
deep-focused
queries into a semi-structured document (those that result in retrieving entire subtrees), the proposed native solutions substantially outperform for the
non-deep-focused
queries, which we demonstrate are at least as important as the deep-focused. We believe that native data layout techniques offer a unique direction for improving the performance of semi-structured data stores for a variety of important workloads. However, given that the proposed native techniques require circumventing current storage stack abstractions, further investigation is warranted before they can be applied to general-purpose storage systems.
Writing the rules of digital privacy
Authors: Rowell Laurie
Published: June 2009

A little rational paranoia goes a long way toward protecting personal digital privacy and identity.
There's a fly in my digital soup
Authors: Conti Gregory
Published: June 2009

A dysfunctional online experience is no accident.
Explorations in statistics: confidence intervals
Authors: Curran-Everett Douglas
Published: June 2009

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This third installment of Explorations in Statistics investigates confidence intervals. A confidence interval is a range that we expect, with some level of confidence, to include the true value of a population parameter such as the mean. A confidence interval provides the same statistical information as the P value from a hypothesis test, but it circumvents the drawbacks of that hypothesis test. Even more important, a confidence interval focuses our attention on the scientific importance of some experimental result.
Construction, calibration, and validation of a simple patch-clamp amplifier for physiology education
Authors: Rouzrokh Ali , Ebrahimi Soltan Ahmed , Mahmoudian Massoud
Published: June 2009

A modular patch-clamp amplifier was constructed based on the Strickholm design, which was initially published in 1995. Various parts of the amplifier such as the power supply, input circuit, headstage, feedback circuit, output and nulling circuits were redesigned to use recent software advances and fabricated using the common lithographic printed circuit board fabrication process and commercially available electronic components. The calibration, validation, and regular recording procedures along with the results of an actual recording of inward Ca2+ currents from PC12 neuronal cells are described in detail. This work describes the construction of a low-cost patch-clamp amplifier and setting up an electrophysiology recording system in a laboratory with regular technical expertise. The constructed amplifier provides an inexpensive yet practical tool for research and teaching purposes while the experience obtained during construction and setting up of the patch-clamp amplifier provides the basic and advanced understanding required for operating an advanced cell potential recording apparatus.
Hypertonic Stress in the Kidney: A Necessary Evil
Authors: Kwon Min Seong , Lim Sun Woo , Kwon H. Moo
Published: June 2009

The interstitium of the renal medulla is hypertonic, imposing deleterious effects on local cells. At the same time, the hypertonicity provides osmotic gradient for water reabsorption and is a local signal for tissue-specific gene expression and differentiation of the renal medulla, which is a critical organ for water homeostasis.
Comparison of Primary Percutaneous Coronary Intervention and Fibrinolytic Therapy in ST-Segment-Elevation Myocardial Infarction
Authors: Huynh Thao , Perron Stephane , O'Loughlin Jennifer , Joseph Lawrence , Labrecque Michel , Tu Jack V. , Théroux Pierre
Published: June 2009

Background—

Published meta-analyses comparing primary percutaneous coronary intervention with fibrinolytic therapy in patients with ST-segment-elevation myocardial infarction include only randomized controlled trials (RCTs). We aim to obviate the limited applicability of RCTs to real-world settings by undertaking meta-analyses of both RCTs and observational studies.

Methods and Results—

We included all RCTs and observational studies, without language restriction, published up to May 1, 2008. We completed separate bayesian hierarchical random-effect meta-analyses for 23 RCTs (8140 patients) and 32 observational studies (185 900 patients). Primary percutaneous coronary intervention was associated with reductions in short-term (≤6-week) mortality of 34% (odds ratio, 0.66; 95% credible interval, 0.51 to 0.82) in randomized trials, and 23% lower mortality (odds ratio, 0.77; 95% credible interval, 0.62 to 0.95) in observational studies. Primary percutaneous coronary intervention was associated with reductions in stroke of 63% in RCTs and 61% in observational studies. At long-term follow-up (≥1 year), primary percutaneous coronary intervention was associated with a 24% reduction in mortality (odds ratio, 0.76; 95% credible interval, 0.58 to 0.95) and a 51% reduction in reinfarction (odds ratio, 0.49; 95% credible interval, 0.32 to 0.66) in RCTs. However, there was no conclusive benefit of primary percutaneous coronary intervention in the long term in the observational studies.

Conclusions—

Compared with fibrinolytic therapy, primary percutaneous coronary intervention was associated with short-term reductions in mortality, reinfarction, and stroke in ST-segment-elevation myocardial infarction. Primary percutaneous coronary intervention was associated with long-term reductions in mortality and reinfarction in RCTs, but there was no conclusive evidence for a long-term benefit in mortality and reinfarction in observational studies.
Relation of Disease Pathogenesis and Risk Factors to Heart Failure With Preserved or Reduced Ejection Fraction
Authors: Lee Douglas S. , Gona Philimon , Vasan Ramachandran S. , Larson Martin G. , Benjamin Emelia J. , Wang Thomas J. , Tu Jack V. , Levy Daniel
Published: June 2009

Background—

The contributions of risk factors and disease pathogenesis to heart failure with preserved ejection fraction (HFPEF) versus heart failure with reduced ejection fraction (HFREF) have not been fully explored.

Methods and Results—

We examined clinical characteristics and risk factors at time of heart failure onset and long-term survival in Framingham Heart Study participants according to left ventricular ejection fraction ≤45% (n=314; 59%) versus >45% (n=220; 41%) and hierarchical causal classification. Heart failure was attributed to coronary heart disease in 278 participants (52%), valvular heart disease in 42 (8%), hypertension in 140 (26%), or other/unknown causes in 74 (14%). Multivariable predictors of HFPEF (versus HFREF) included elevated systolic blood pressure (odds ratio [OR]=1.13 per 10 mm Hg; 95% confidence interval [CI], 1.04 to 1.22), atrial fibrillation (OR=4.23; 95% CI, 2.38 to 7.52), and female sex (OR=2.29; 95% CI, 1.35 to 3.90). Conversely, prior myocardial infarction (OR=0.32; 95% CI, 0.19 to 0.53) and left bundle-branch block QRS morphology (OR=0.21; 95% CI, 0.10 to 0.46) reduced the odds of HFPEF. Long-term prognosis was grim, with a median survival of 2.1 years (5-year mortality rate, 74%), and was equally poor in men and women with HFREF or HFPEF.

Conclusions—

Among community patients with new-onset heart failure, there are differences in causes and time-of-onset clinical characteristics between those with HFPEF versus HFREF. In people with HFREF, mortality is increased when coronary heart disease is the underlying cause. These findings suggest that heart failure with reduced left ventricular systolic function and heart failure with preserved left ventricular systolic function are partially distinct entities, with potentially different approaches to early detection and prevention.
Predicting the 30-Year Risk of Cardiovascular Disease
Authors: Pencina Michael J. , D'Agostino Ralph B. , Larson Martin G. , Massaro Joseph M. , Vasan Ramachandran S.
Published: June 2009

Background—

Present cardiovascular disease (CVD) risk prediction algorithms were developed for a ≤10-year follow up period. Clustering of risk factors at younger ages and increasing life expectancy suggest the need for longer-term risk prediction tools.

Methods and Results—

We prospectively followed 4506 participants (2333 women) of the Framingham Offspring cohort aged 20 to 59 years and free of CVD and cancer at baseline examination in 1971–1974 for the development of “hard” CVD events (coronary death, myocardial infarction, stroke). We used a modified Cox model that allows adjustment for competing risk of noncardiovascular death to construct a prediction algorithm for 30-year risk of hard CVD. Cross-validated survival C statistic and calibration χ
2
were used to assess model performance. The 30-year hard CVD event rates adjusted for the competing risk of death were 7.6% for women and 18.3% for men. Standard risk factors (male sex, systolic blood pressure, antihypertensive treatment, total and high-density lipoprotein cholesterol, smoking, and diabetes mellitus), measured at baseline, were significantly related to the incidence of hard CVD and remained significant when updated regularly on follow-up. Body mass index was associated positively with 30-year risk of hard CVD only in models that did not update risk factors. Model performance was excellent as indicated by cross-validated discrimination C=0.803 and calibration χ
2
=4.25 (
P
=0.894). In contrast, 30-year risk predictions based on different applications of 10-year functions proved inadequate.

Conclusions—

Standard risk factors remain strong predictors of hard CVD over extended follow-up. Thirty-year risk prediction functions offer additional risk burden information that complements that of 10-year functions.
Longitudinal Tracking of Left Ventricular Mass Over the Adult Life Course
Authors: Lieb Wolfgang , Xanthakis Vanessa , Sullivan Lisa M. , Aragam Jayashri , Pencina Michael J. , Larson Martin G. , Benjamin Emelia J. , Vasan Ramachandran S.
Published: June 2009

Background—

Information is limited on the longitudinal tracking of left ventricular (LV) mass over the adult life course and the determinants of such change.

Methods and Results—

We used multilevel modeling to evaluate the correlates of LV mass prospectively over a 16-year period in 4217 Framingham study participants (mean age 45 years, 53% women) using up to 4 serial routine echocardiographic observations on each individual (11 762 observations). Age, sex, body mass index, systolic blood pressure, antihypertensive treatment, smoking, and diabetes mellitus were related to longitudinal measures of LV mass. Women and participants with diabetes mellitus experienced a steeper increase in LV mass with advancing age (compared with men and those without diabetes mellitus;
P
for interactions <0.0001 and 0.0003, respectively). Women also displayed greater increments in LV mass with increasing body mass index (compared with men,
P
=0.04 for interaction). Participants with optimal values of these risk factors experienced lesser increases in LV mass over time. Analyses evaluating short-term (4-year) changes in LV mass (2605 unique individuals providing 4494 observations) identified the same key determinants that influenced its long-term trajectory (ie, body mass index, sex, systolic blood pressure, antihypertensive treatment, and smoking).

Conclusions—

Our longitudinal observations on a large community-based sample identified higher blood pressure, excess adiposity, smoking, and diabetes mellitus as fundamental determinants of LV mass tracking over the adult life course. These observations are consistent with the notion that maintenance of optimal levels of these risk factors in midlife will reduce the burden of LV hypertrophy, and possibly heart failure, in older age.
DITPA (3,5-Diiodothyropropionic Acid), a Thyroid Hormone Analog to Treat Heart Failure
Authors: Goldman Steven , McCarren Madeline , Morkin Eugene , Ladenson Paul W. , Edson Robert , Warren Stuart , Ohm Janet , Thai Hoang , Churby Lori , Barnhill Jamie , O'Brien Terrence , Anand Inder , Warner Alberta , Hattler Brack , Dunlap Mark , Erikson John , Shih Mei-Chiung , Lavori Phil
Published: June 2009

Background—In animal studies and a pilot trial in patients with congestive heart failure, the thyroid hormone analog 3,5 diiodothyropropionic acid (DITPA) had beneficial hemodynamic effects.

Methods and Results—This was a phase II multicenter, randomized, placebo-controlled, double-blind trial of New York Heart Association class II to IV congestive heart failure patients randomized (2:1) to DITPA or placebo and treated for 6 months. The study enrolled 86 patients (n=57 to DITPA, n=29 to placebo). The primary objective was to assess the effect of DITPA on a composite congestive heart failure end point that classifies patients as improved, worsened, or unchanged based on symptom changes and morbidity/mortality. DITPA was poorly tolerated, which obscured the interpretation of congestive heart failure-specific effects. Fatigue and gastrointestinal complaints, in particular, were more frequent in the DITPA group. DITPA increased cardiac index (by 18%) and decreased systemic vascular resistance (by 11%), serum cholesterol (−20%), low-density lipoprotein cholesterol (−30%), and body weight (−11 lb). Thyroid-stimulating hormone was suppressed in patients given DITPA, which reflects its thyromimetic effect; however, no symptoms or signs of potential hypothyroidism or thyrotoxicosis were seen.

Conclusions—DITPA improved some hemodynamic and metabolic parameters, but there was no evidence for symptomatic benefit in congestive heart failure.
Risk of Assessing Mortality Risk in Elective Cardiac Operations
Authors: Ranucci Marco , Castelvecchio Serenella , Menicanti Lorenzo , Frigiola Alessandro , Pelissero Gabriele
Published: June 2009

Background—

Several mortality risk scores exist in cardiac surgery. All include a considerable number of independent risk factors. In elective cardiac surgery patients, the operative mortality is low, the number of events recorded per year is limited, and the risk model may be overfitted. The present study aims to develop and validate an operative mortality risk score for elective patients based on a limited number of factors.

Methods and Results—

The development series included 4557 adult patients who had undergone an elective cardiac operation at our institution from 2001 to 2003; the validation series includes the 4091 patients who subsequently underwent an operation. Three independent factors were included in the mortality risk model: age, creatinine, and left ventricular ejection fraction (ACEF). The ACEF score was computed as follows: age (years)/ejection fraction (%)+1 (if serum creatinine value was >2 mg/dL). The ACEF score was compared with 5 other risk scores in the validation series. Discriminatory power (accuracy) was defined with a receiver-operating characteristics analysis. The best accuracy was achieved by the Cleveland Clinic score (0.812), with ACEF score just below it (0.808). In coronary operations, the 2 scores performed equally well (0.815 versus 0.813), and in isolated coronary operations, the best accuracy was achieved by ACEF (0.826), with the Cleveland Clinic score at 0.806.

Conclusion—

A risk model limited to 3 independent predictors has similar or better accuracy and calibration compared with more complex risk scores if applied to elective cardiac operations.
Rosiglitazone Reduces the Development and Rupture of Experimental Aortic Aneurysms
Authors: Jones Alun , Deb Rajdeep , Torsney Evelyn , Howe Franklyn , Dunkley Mathew , Gnaneswaran Yanosha , Gaze David , Nasr Hosaam , Loftus Ian M. , Thompson Mathew M. , Cockerill Gillian W.
Published: June 2009

Background—Development and rupture of aortic aneurysms involve a combination of complex biological processes. Rosiglitazone, a peroxisome proliferator-activated receptor-γ agonist, has been shown to have a broad spectrum of effects in vivo. The hypothesis that rosiglitazone would reduce aneurysm expansion or rupture was tested in the angiotensin II (Ang II)-induced hypercholesterolemic mouse model.

Methods and Results—Apolipoprotein E-deficient mice, 12 months of age, were allocated to 4 groups. Three groups were infused with Ang II (1 μg · min−1· kg−1), and the fourth was infused with saline. Rosiglitazone was given 1 week before infusion and 1 week after infusion. At day 28, aortic size was measured, and tissues were collected for analyses. Both pretreatment and posttreatment with rosiglitazone inhibited the occurrence of fatal rupture (11 of 30 versus 0 of 30 versus 0 of 15;P=0.0013) and reduced maximal dilatation of the aorta (4.6±0.13 versus 2.4±0.48 versus 2.15±0.46 mm2;P<0.0001). Blood glucose, total cholesterol, body weight, and atherosclerosis did not differ between groups. Pretreatment with rosiglitazone inhibited the Ang II-induced expression of angiotensin type 1a Ang II receptor while having no effect on the angiotensin type 2 Ang II receptor, in addition to reducing Ang II-induced expression of E-selectin, tumor necrosis factor-α, and interleukin-6.

Conclusions—Pretreatment or posttreatment with RGZ reduced aortic expansion and rupture in this mouse model. Reduction of lesions in animals pretreated with rosiglitazone is concomitant with decreased expression of inflammatory mediators. Further studies are needed to elucidate the precise mechanism.
Ventral Lamina Terminalis Mediates Enhanced Cardiovascular Responses of Rostral Ventrolateral Medulla Neurons During Increased Dietary Salt
Authors: Adams Julye M. , Bardgett Megan E. , Stocker Sean D.
Published: June 2009

Increased dietary salt enhances sympathoexcitatory and sympathoinhibitory responses evoked from the rostral ventrolateral medulla (RVLM). The purpose of the present study was to determine whether neurons of the forebrain lamina terminalis (LT) mediated these changes in the RVLM. Male Sprague-Dawley rats with and without LT lesions were fed normal chow and given access to water or 0.9% NaCl for 14 to 15 days. Unilateral injection ofl-glutamate into the RVLM produced significantly larger increases in renal sympathetic nerve activity and arterial blood pressure of sham rats ingesting 0.9% NaCl versus water. However, these differences were not observed between ventral LT-lesioned rats drinking 0.9% NaCl versus water. Similar findings were observed when angiotensin II or γ-aminobutyric acid was injected into the RVLM. Interestingly, a subset of animals drinking 0.9% but with damage restricted to the organum vasculosum of the lamina terminalis did not show enhanced responses tol-glutamate or γ-aminobutyric acid. In marked contrast, RVLM injection ofl-glutamate or γ-aminobutyric acid produced exaggerated sympathetic nerve activity and arterial blood pressure responses in animals drinking 0.9% NaCl versus water after an acute ventral LT lesion or chronic lesion of the subfornical organ. Additional experiments demonstrated that plasma sodium concentration and osmolality were increased at night in rats ingesting 0.9% NaCl. These findings suggest that neurons of the ventral LT mediate the ability of increased dietary salt to enhance the responsiveness of RVLM sympathetic neurons.
Attenuation of Angiotensin II–Induced Vascular Dysfunction and Hypertension by Overexpression of Thioredoxin 2
Authors: Widder Julian D. , Fraccarollo Daniela , Galuppo Paolo , Hansen Jason M. , Jones Dean P. , Ertl Georg , Bauersachs Johann
Published: June 2009

Reactive oxygen species increase in the cardiovascular system during hypertension and in response to angiotensin II. Because mitochondria contribute to reactive oxygen species generation, we sought to investigate the role of thioredoxin 2, a mitochondria-specific antioxidant enzyme. Mice were created with overexpression of human thioredoxin 2 (Tg
hTrx2
mice) and backcrossed to C57BL/6J mice for ≥6 generations. Twelve-week-old male Tg
hTrx2
or littermate wild-type mice were made hypertensive by infusion of angiotensin II (400 ng/kg per minute) for 14 days using osmotic minipumps. Systolic arterial blood pressure was not different between Tg
hTrx2
and wild-type animals under baseline conditions (101±1 respective 102±1 mm Hg). The angiotensin II–induced hypertension in wild-type mice (145±2 mm Hg) was significantly attenuated in Tg
hTrx2
mice (124±1 mm Hg;
P
<0.001). Aortic endothelium-dependent relaxation was significantly reduced in wild-type mice after angiotensin II infusion but nearly unchanged in transgenic mice. Elevated vascular superoxide and hydrogen peroxide levels, as well as expression of NADPH oxidase subunits in response to angiotensin II infusion, were significantly attenuated in Tg
hTrx2
mice. Mitochondrial superoxide anion levels were augmented after angiotensin II infusion in wild-type mice, and this was blunted in Tg
hTrx2
mice. Angiotensin II infusion significantly increased myocardial superoxide formation, heart weight, and cardiomyocyte size in wild-type but not in Tg
hTrx2
mice. These data indicate a major role for mitochondrial thioredoxin 2 in the development of cardiovascular alterations and hypertension during chronic angiotensin II infusion. Thioredoxin 2 may represent an important therapeutic target for the prevention and treatment of hypertension and oxidative stress.
Estrous Cycle–Dependent Neurovascular Dysfunction Induced by Angiotensin II in the Mouse Neocortex
Authors: Capone Carmen , Anrather Josef , Milner Teresa A. , Iadecola Costantino
Published: June 2009

Female mice are protected from the cerebrovascular dysfunction induced by angiotensin II (Ang II), an effect attributed to estrogen. We examined whether such cerebrovascular protection from Ang II is related to the estrous cycle. Cerebral blood flow was monitored by laser-Doppler flowmetry in anesthetized (urethane-chloralose) C57BL/6 female mice equipped with a cranial window. The phase of the estrous cycle was determined by vaginal smear cytology and plasma estrogen measurement. Ang II (0.25 μg/kg per minute, IV, 30 to 45 minutes) elevated arterial pressure (15 to 20 mm Hg) equally across the estrous cycle. However, in proestrus and estrus, phases in which estrogen is relatively high, Ang II did not impair the increase in the cerebral blood flow induced by neural activity or by endothelium-dependent vasodilators (P>0.05 from vehicle). In contrast, in diestrus (lower estrogen), Ang II induced a marked cerebrovascular dysfunction comparable to that of male mice. For example, the cerebral blood flow responses to whisker stimulation and to the endothelium-dependent vasodilator acetylcholine were attenuated by 41±12% and 49±12%, respectively (P<0.05; n=6 per group). The protection from the cerebrovascular effects of Ang II in proestrus was abolished by the estrogen receptor inhibitor ICI182,780. Ang II also increased production of free radicals in cerebral blood vessels in diestrus (+116±13%;P<0.05) but not in proestrus and estrus (P>0.05 from control). Topical treatment with ICI182,780 reestablished Ang II–induced oxidative stress in proestrus (P>0.05 from diestrus). We conclude that the protection from the neurovascular dysfunction induced by acute administration of Ang II in females depends on the estrous cycle and may underlie the increased propensity to cerebrovascular damage associated with low estrogen states.
Pulse Wave Velocity Assessment by External Noninvasive Devices and Phase-Contrast Magnetic Resonance Imaging in the Obese
Authors: Joly Laure , Perret-Guillaume Christine , Kearney-Schwartz Anna , Salvi Paolo , Mandry Damien , Marie Pierre-Yves , Karcher Gilles , Rossignol Patrick , Zannad Faiez , Benetos Athanase
Published: June 2009

Carotid-femoral pulse wave velocity (PWV) is considered the gold-standard measurement of arterial stiffness. Obesity, however, can render inaccurate the measurement of PWV by external noninvasive devices. Phase-contrast MRI allows the determination of aortic PWV in multiple aortic locations with intra-arterial distance measurements, as well as the assessment of aortic mechanical properties. The purpose of this study was to assess the reliability of external carotid-femoral PWV values measured by well-validated external devices in comparison with MRI acquisitions of PWV and aortic mechanical properties in a population of obese subjects. PWV was measured with PulsePen and Complior II devices in 32 volunteers (18 men and 14 women), aged 46 to 65 years (mean: 55.7±5.1 years), presenting with isolated abdominal obesity, with a waist circumference >102 cm for men and >88 cm for women, and a body mass index between 27 and 35. These results were then compared with MRI PWV values and cross-sectional MRI thoracic aorta distensibility values. MRI PWV values were positively correlated with PWV measured by both PulsePen (
r
=0.47;
P
=0.005) and Complior (
r
=0.43;
P
=0.01). Aortic cross-sectional stiffness was positively correlated with PulsePen PWV (
r
=0.42;
P
=0.02). The same trend was also observed with Complior PWV (
r
=0.33;
P
=0.06). This is the first study comparing transcutaneous PWV measurements with MRI aortic elastic properties in obese subjects. Our results indicate that, for body mass index values ≤35 kg m
−2
, PWV measured externally with Complior or PulsePen validly reflect values obtained directly in the thoracic aorta through MRI.
Initial-Condition Sensitivities and the Predictability of Downslope Winds
Authors: Reinecke Patrick A. , Durran Dale R.
Published: June 2009

The sensitivity of downslope wind forecasts to small changes in initial conditions is explored by using 70-member ensemble simulations of two prototypical windstorms observed during the Terrain-Induced Rotor Experiment (T-REX). The 10 weakest and 10 strongest ensemble members are composited and compared for each event.

In the first case, the 6-h ensemble-mean forecast shows a large-amplitude breaking mountain wave and severe downslope winds. Nevertheless, the forecasts are very sensitive to the initial conditions because the difference in the downslope wind speeds predicted by the strong- and weak-member composites grows to larger than 28 m s−1 over the 6-h forecast. The structure of the synoptic-scale flow one hour prior to the windstorm and during the windstorm is very similar in both the weak- and strong-member composites.

Wave breaking is not a significant factor in the second case, in which the strong winds are generated by a layer of high static stability flowing beneath a layer of weaker mid- and upper-tropospheric stability. In this case, the sensitivity to initial conditions is weaker but still significant. The difference in downslope wind speeds between the weak- and strong-member composites grows to 22 m s−1 over 12 h. During and one hour before the windstorm, the synoptic-scale flow exhibits appreciable differences between the strong- and weak-member composites. Although this case appears to be more predictable than the wave-breaking event, neither case suggests that much confidence should be placed in the intensity of downslope winds forecast 12 or more hours in advance.
Changes in the Global Sulfate Burden due to Perturbations in Global CO2 Concentrations
Authors: Ackerley Duncan , Highwood Eleanor J. , Frame David J. , Booth Ben B. B.
Published: June 2009

A large ensemble of general circulation model (GCM) integrations coupled to a fully interactive sulfur cycle scheme were run on the climateprediction.net platform to investigate the uncertainty in the climate response to sulfate aerosol and carbon dioxide (CO2) forcing. The sulfate burden within the model (and the atmosphere) depends on the balance between formation processes and deposition (wet and dry). The wet removal processes for sulfate aerosol are much faster than dry removal and so any changes in atmospheric circulation, cloud cover, and precipitation will feed back on the sulfate burden. When CO2 is doubled in the Hadley Centre Slab Ocean Model (HadSM3), global mean precipitation increased by 5%; however, the global mean sulfate burden increased by 10%. Despite the global mean increase in precipitation, there were large areas of the model showing decreases in precipitation (and cloud cover) in the Northern Hemisphere during June–August, which reduced wet deposition and allowed the sulfate burden to increase. Further experiments were also undertaken with and without doubling CO2 while including a future anthropogenic sulfur emissions scenario. Doubling CO2 further enhanced the increases in sulfate burden associated with increased anthropogenic sulfur emissions as observed in the doubled CO2-only experiment. The implications are that the climate response to doubling CO2 can influence the amount of sulfate within the atmosphere and, despite increases in global mean precipitation, may act to increase it.
Evaluation of Incremental Improvements to Quantitative Precipitation Estimates in Complex Terrain
Authors: Gourley Jonathan J. , Jorgensen David P. , Matrosov Sergey Y. , Flamig Zachary L.
Published: June 2009

Advanced remote sensing and in situ observing systems employed during the Hydrometeorological Testbed experiment on the American River basin near Sacramento, California, provided a unique opportunity to evaluate correction procedures applied to gap-filling, experimental radar precipitation products in complex terrain. The evaluation highlighted improvements in hourly radar rainfall estimation due to optimizing the parameters in the reflectivity-to-rainfall (Z–R) relation, correcting for the range dependence in estimating R due to the vertical variability in Z in snow and melting-layer regions, and improving low-altitude radar coverage by merging rainfall estimates from two research radars operating at different frequencies and polarization states. This evaluation revealed that although the rainfall product from research radars provided the smallest bias relative to gauge estimates, in terms of the root-mean-square error (with the bias removed) and Pearson correlation coefficient it did not outperform the product from a nearby operational radar that used optimized Z–R relations and was corrected for range dependence. This result was attributed to better low-altitude radar coverage with the operational radar over the upper part of the basin. In these regions, the data from the X-band research radar were not available and the C-band research radar was forced to use higher-elevation angles as a result of nearby terrain and tree blockages, which yielded greater uncertainty in surface rainfall estimates. This study highlights the challenges in siting experimental radars in complex terrain. Last, the corrections developed for research radar products were adapted and applied to an operational radar, thus providing a simple transfer of research findings to operational rainfall products yielding significantly improved skill.
Relating the Drag Coefficient and the Roughness Length over the Sea to the Wavelength of the Peak Waves
Authors: Andreas Edgar L.
Published: June 2009

The standard 10-m reference height for computing the drag coefficient over the sea is admittedly arbitrary. The literature contains occasional suggestions that a scaling length based on the wavelength of the peak waves λp is a more natural reference height. Attempts to confirm this hypothesis must be done carefully, however, because of the potential for fictitious correlation between nondimensional dependent and independent variables. With the DMAJ dataset as an example, this study reviews the issue of fictitious correlation in analyses that use λp/2 as the reference height for evaluating the drag coefficient and that use kp (=2π/λp) as a scale for the roughness length z0. (The DMAJ dataset is a compilation of four individual datasets; D, M, A, and J, respectively, identify the lead authors of the four studies: Donelan, Merzi, Anctil, and Janssen.) This dataset has been used in several previous studies to evaluate the dependence of kpz0 and the drag coefficient evaluated at λp/2 on the nondimensional wave parameter ω* = ωpu*/g. Here ωp is the radian frequency of the peak in the wind–wave spectrum, u* is the friction velocity, and g is the acceleration of gravity. Because the DMAJ dataset does not, however, include independent measurements of λp and ωp, λp had to be inferred from measurements of ωp through the wave dispersion relation. The presence of ωp in both the dependent and independent variables, therefore, exacerbates the fictitious correlation. One conclusion, thus, is that using λp to formulate the drag coefficient and the nondimensional roughness length as functions of a nondimensional variable that includes ωp requires a dataset with independent measurements of λp and ωp.
Stress-dependent Moisture Diffusion in Composite Materials
Authors: Youssef G. , Fréour S. , Jacquemin F.
Published: June 2009

Experiments have indicated that the diffusion properties of a penetrant organic matrix composite system may change with time due to evolution of the internal mechanical strain states experienced by the constituting matrix of the composite plies. A multi-scale approach coupling the internal mechanical states, predicted by continuum medium mechanics, and their localization at the ply-constituent scale to the traditional Fick's law governing the moisture diffusion process was used in order to achieve the modeling of the response of composite laminates submitted to environmental hygroscopic loads, from the transient part of the diffusion process to its permanent stage. Various numerical practical cases were considered: the effects of the internal swelling strains on the time- and space-dependent diffusion coefficient, maximum moisture absorption capacity, moisture content, and states of internal stresses are extensively studied and discussed.
Influence of Chemical Modification and Filler Loading on Fundamental Properties of Bamboo Fibers Reinforced Polypropylene Composites
Authors: Lee Sun-Young , Chun Sang-Jin , Doh Geum-Hyun , Kang In-Aeh , Lee Soo , Paik Ki-Hyon
Published: June 2009

The effects of chemical modification (silane coupling) and filler loading on the fundamental properties of the bamboo fiber (BF) filled polypropylene (PP) bio-composites were investigated in this study. Mechanical properties of the PP/ BF composites, such as the tensile strength, flexural strength, and impact strength decreased as BF loading increased. However, the tensile modulus, flexural modulus, and water absorption were increased by the increase of the BF loading. The addition of aminopropyltrimethoxysilane (AS) and tetramethoxy orthosilicate (TMOS) after the alkali pretreatment for the BF increased all the tensile, flexural, impact strength, and water desorption of the resultant composites, resulting from the improved adhesion between the BF and PP matrix. This tendency was more obvious with the increase of the BF loading. The melting temperature, melting enthalpy, crystallization enthalpy, and crystallinity were decreased by the increase of BF loading and the AS and TMOS treatments. One the other hand, the crystalline temperature was increased by the addition of the BF, AS, and TMOS. Hence, AS and TMOS are considered as effectual coupling agents for the PP/BF composite systems.
Doing More With Less
Authors: Sargent Tanja C. , Hannum Emily
Published: June 2009

Teacher professional learning communities provide environments in which teachers engage in regular research and collaboration. They have been found effective as a means for connecting professional learning to the day-to-day realities faced by teachers in the classroom. In this article, the authors draw on survey data collected in primary schools serving 71 villages in rural Gansu Province as well as transcripts from in-depth interviews with 30 teachers. Findings indicate that professional learning communities penetrate to some of China's most resource-constrained schools but that their nature and development are shaped by institutional supports, principal leadership, and teachers' own initiative.
The Complexities of Systems Change in Creating Equity for Students With Disabilities in Urban Schools
Authors: Kozleski Elizabeth B. , Smith Anne
Published: June 2009

This article explores the complexities of urban school improvement and systems change through the lens of educational equity policy initiatives. The authors situate urban schools within a critical context where contested identity politics, sociopolitical agendas, and economic stratification marginalize culturally and linguistically diverse students. The study uses the elements of a framework for systemic change and examines urban schools. Analyzing local educational change, the authors examine the interaction between structural reform, collective, community narratives about children, and their impacts on the urban schools. Along with lessons learned from school improvement and technical assistance activities, these perspectives look at how local-activity arenas respond to reform and how understanding the complexities of local practice could inform the next-generation policy initiatives. Without deep and shared understanding, the strategies employed to achieve short-term improvements will circumvent work on the changes required to shift students from the margins while simultaneously changing the mainstream conditions.
Meeting the Needs of English Language Learners With Disabilities in Urban Settings
Authors: Rodriguez Diane
Published: June 2009

English-language learners with disabilities are capable of learning and are entitled to high-quality educational experiences. Their academic and social needs should be considered from multiple perspectives. To be effective, bilingual special education programs must implement best practices. This article highlights findings from research devoted to examining the influence of language on teaching and learning.
Antecedents and Consequences of Social Identity Complexity: Intergroup Contact, Distinctiveness Threat, and Outgroup Attitudes
Authors: Schmid Katharina , Hewstone Miles , Tausch Nicole , Cairns Ed , Hughes Joanne
Published: June 2009

Social identity complexity defines people's more or less complex cognitive representations of the interrelationships among their multiple ingroup identities. Being high in complexity is contingent on situational, cognitive, or motivational factors, and has positive consequences for intergroup relations. Two survey studies conducted in Northern Ireland examined the extent to which intergroup contact and distinctiveness threat act as antecedents, and outgroup attitudes as consequences, of social identity complexity. In both studies, contact was positively, and distinctiveness threat negatively, associated with complex multiple ingroup perceptions, whereas respondents with more complex identity structures also reported more favorable outgroup attitudes. Social identity complexity also mediated the effects of contact and distinctiveness threat on attitudes. This research highlights that the extent to which individuals perceive their multiple ingroups in more or less complex and differentiated ways is of central importance to understanding intergroup phenomena.
Parenting Self-Efficacy and Social Support in Japan and the United States
Authors: Suzuki Sawako , Holloway Susan D. , Yamamoto Yoko , Mindnich Jessica D.
Published: June 2009

To understand the conditions that give rise to parenting self-efficacy in Japan and the United States, the authors have investigated its relation to the perceptions of support available to mothers of children in the final year of preschool ( N = 235; n = 121 in United States, n = 114 in Japan). Hierarchical regression analysis indicates that in both countries, women who experience higher parenting self-efficacy report more positive childhood memories of parental support and greater satisfaction with husband’s and friends’ support. Mothers in the United States are significantly more self-efficacious than are mothers in Japan, even after controlling for the effects of the support predictors. A follow-up mediational analysis reveals that Japanese women’s lower levels of parenting self-efficacy are partially attributable to their low satisfaction with husband’s support.
The Impact of Active Consent Procedures on Nonresponse and Nonresponse Error in Youth Survey Data
Authors: Courser Matthew W. , Shamblen Stephen R. , Lavrakas Paul J. , Collins David , Ditterline Paul
Published: June 2009

This article reports results from a student survey fielded using an experimental design with 14 Kentucky school districts. Seven of the 14 districts were randomly assigned to implement the survey with active consent procedures; the other seven districts implemented the survey with passive consent procedures. We used our experimental design to investigate the impact of consent procedures on (a) participation rates, (b) demographic characteristic of the survey samples, and (c) estimates of alcohol, tobacco, and other drugs (ATOD) use. We found that the use of active consent procedures resulted in reduced response rates, underrepresentation of male students and older students, and lower lifetime and past 30-day prevalence rates for most drugs and for most antisocial behaviors. Methodological implications of these findings are discussed along with directions for further research.
A randomized controlled trial of a controlled breathing protocol on heart rate variability following myocardial infarction or coronary artery bypass graft surgery
Authors: Adams Jenny , Julian Peter , Hubbard Matthew , Hartman Julie , Baugh Sally , Segrest Wendy , Russell Jenny , McDonnell Jeff , Wheelan Kevin
Published: June 2009

Objectives: To determine whether a controlled breathing programme increases heart rate variability following an acute myocardial infarction and/or coronary artery bypass graft surgery.

Rationale: Heart rate variability is reduced following a myocardial infarction, and low heart rate variability is associated with a high mortality risk. By changing tidal volume and rate of breathing, individuals can alter beat-to-beat heart rate variability. It is hypothesized that heart rate increases with inspiration and decreases with exhalation, and that deep slow breathing enhances respiratory sinus arrhythmia, increasing heart rate variability.

Design: Randomized controlled trial.

Setting: Cardiac rehabilitation programme at a large academic medical centre in North Texas.

Subjects: From 2001 to 2005, 44 patients, age 46—65 years, who had a myocardial infarction and/or undergone coronary artery bypass graft surgery 1—8 weeks previously and were referred to the Cardiac Rehabilitation Program.

Intervention: Patients were randomized to either usual cardiac rehabilitation or cardiac rehabilitation with controlled breathing (6 breaths/min for 10 minutes twice daily during the eight-week treatment period).

Main measures: Weekly measurements of total power and standard deviation of the mean normal to normal RR interval (SDNN), and fortnightly measurements of respiratory sinus arrhythmia were taken using Biocom Technologies Heart Rhythm Scanner and Tracker software.

Results: No significant difference in change were seen between groups in SDNN (P = 0.3984), baseline respiratory sinus arrhythmia (P = 0.6556) or total power (P = 0.6184).

Conclusion: Results suggest participation in the controlled breathing programme offered no additional benefit in increasing heart rate variability following myocardial infarction or coronary artery bypass graft surgery. However, 77% of study patients were on heart rate-lowering medications, which may have masked changes in heart rate variability.
Development of Goal-Sensitive Health-Related Utility Assessment Procedures
Authors: Schwartz Alan , Hazen Gordon B. , Leifer Ariel , Heckerling Paul S.
Published: June 2009

Purpose. To measure the degree to which people express willingness to trade life or health for nonmedical goals. Method. In 3 studies, outpatients provided important life goals. In study 1, patients performed time-tradeoff between life-years and goal achievement and chose between states that varied in goal achievement, life expectancy, and disability; in study 2, patients made choices that traded off health state and goal achievement; in study 3, patients performed time-tradeoff assessments in 3 different goal achievement contexts. Results. In study 1 (n = 58), participants were eager to trade life-years for goal achievement, trading, on average, 71% of their remaining life for certain achievement v. certain nonachievement or 54% of their remaining life for their expected likelihood of achievement v. nonachievement. Life expectancy, disability status, and goal achievement each had a significant main effect on utility. In study 2 (n = 54), participants equally preferred a moderately impaired health state with goal achievement to perfect health without goal achievement and more strongly preferred the moderately impaired state with goal achievement than other less impaired states without goal achievement. Study 3 (n = 62) demonstrated that the mere discussion of goals and goal achievement or nonachievement in the context of a standard time-tradeoff assessment (without trading off goals) did not impact the assessment. Conclusions. Nonmedical life goals are important determinants of quality of life. People express willingness to trade off life and health in pursuit of these goals, which are extrinsic to the standard quality-adjusted life-year model.
Exploring Negative Group Dynamics
Authors: Xia Ling , Yuan Y. Connie , Gay Geri
Published: June 2009

Most previous social network studies have focused on the positive aspects of social relationships. In contrast, this research examined how the negative aspects of social networks in work groups can influence individual performance within the group. Accordingly, two studies were conducted to make this assessment. The first study examined the effect of negative relations and frequency of communication on performance among student groups. The second study investigated how the Five Factor Model of personality and position in adversarial networks interacted to influence individuals' performance. Although results of the first study indicated that frequent communication with others could make a person more likeable, consequently helping him or her perform better, the second study showed that those individuals disliked by others were less likely to achieve a good performance rating, despite their conscientiousness, emotional stability, or openness to experiences.
Where Do New Firms Come From?
Authors: Steier Lloyd
Published: June 2009

The creation of new firms is an important economic activity; however, understanding of the actual venture-creation process remains limited. P. Rodriguez, C. S. Tuggle, and S. M. Hackett (2009) address this deficiency by adopting an internal social capital perspective and examining the effects of family financial, social, health, and ethnic contexts on firm creation. This commentary extends their work by reinforcing that households are important units of analysis and are usefully viewed as incubators and opportunity platforms for venture creation. It further suggests that social capital has a nested nature and that households should be viewed as part of the overall welfare mix.