bluuebunny/crossref_metadata_2025 huggingface dataset:
Do Statins Improve Outcomes and Reduce the Incidence of Vasospasm After Aneurysmal Subarachnoid Hemorrhage
Authors: Sillberg Victoria A.H. , Wells George A. , Perry Jeffrey J.
Published: July 2008

Background and Purpose—

Subarachnoid hemorrhage (SAH) is a relatively rare cause of stroke with a high rate of morbidity and mortality, primarily due to the occurrence of delayed vasospasm. To date, many therapies have been proposed to help prevent vasospasm, but very few have been proven effective. The initiation of statin therapy after SAH may be effective in reducing the incidence of vasospasm; however, the only studies that have examined this effect have been small. This meta-analysis attempted to determine whether statins reduce morbidity and mortality after aneurysmal SAH.

Methods—

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for randomized, controlled trials relating to the use of statins in SAH. Foreign language and abstract articles were included. Two independent reviewers assessed studies for eligibility, data extraction, and quality. Primary outcome was the incidence of radiographically confirmed clinical vasospasm; secondary outcomes were incidence of delayed ischemic deficits and mortality.

Results—

The incidence of vasospasm (relative risk [RR]=0.73; 95% CI, 0.54 to 0.99), delayed ischemic deficits (RR=0.38; 95% CI, 0.17 to 0.83), and mortality (RR=0.22; 95% CI, 0.06 to 0.82) were significantly reduced in the statin group. For these outcomes, we calculated a number needed to treat of 6.25, 5, and 6.7, respectively.

Conclusions—

Initiation of statin therapy after aneurysmal SAH significantly reduces the incidence of vasospasm, delayed ischemic deficits, and mortality. This is consistent with animal research and retrospective studies and supports the routine use of statins in the care of patients with aneurysmal SAH.
Blood Biomarkers in the Diagnosis of Ischemic Stroke
Authors: Whiteley William , Tseng Mei-Chiun , Sandercock Peter
Published: July 2008

Background and Purpose—

The diagnosis of ischemic stroke can be difficult. CT may be normal in the early stages of ischemic stroke or in patients with minor symptoms and MR is not always possible. Many blood markers have been proposed for the diagnosis of stroke in the acute setting.

Methods and Results—

We have systematically reviewed the diagnostic literature and found 21 studies testing 58 single biomarkers and 7 panels of several biomarkers. Although all show either a high sensitivity or specificity, there are limitations in the design and reporting of all the studies that mean no biomarker can be recommended for use in clinical practice.

Conclusions—

We make recommendations for the design and reporting of studies of diagnostic blood biomarkers in stroke.
Perfusion Augmentation in Acute Stroke Using Mechanical Counter-Pulsation–Phase IIa
Authors: Alexandrov Anne W. , Ribo Marc , Wong Ka Sing , Sugg Rebecca M. , Garami Zsolt , Jesurum Jill T. , Montgomery Baxter , Alexandrov Andrei V.
Published: July 2008

Background and Purpose—

External counterpulsation (ECP) improves coronary perfusion, increases left ventricular stroke volume similar to intraaortic balloon counterpulsation, and recruits arterial collaterals within ischemic territories. We sought to determine ECPs effect on middle cerebral artery (MCA) blood flow augmentation in normal controls as a first step to support future clinical trials in acute stroke.

Methods—

Healthy volunteers were recruited and screened for exclusions. Bilateral 2-MHz pulsed wave transcranial Doppler (TCD) probes were mounted by head frame, and baseline M1 MCA TCD measurements were obtained. ECP was then initiated using standard procedures for 30 minutes, and TCD readings were repeated at 5 and 20 minutes. Physiological correlates associated with ECP-TCD waveform morphology were identified, and measurable criteria for TCD assessment of ECP arterial mean flow velocity (MFV) augmentation were constructed.

Results—

Five subjects were enrolled in the study. Preprocedural M1 MCA TCD measurements were within normal limits. Onset of ECP counterpulsation produced an immediate change in TCD waveform configuration with the appearance of a second upstroke at the dicrotic notch, labeled peak diastolic augmented velocity (PDAV). Although end-diastolic velocities did not increase, both R-MCA and L-MCA PDAVs were significantly higher than baseline end-diastolic values (
P
<0.05 Wilcoxon rank-sum test) at 5 and 20 minutes. Augmented MFVs (aMFVs) were also significantly higher than baseline MFV in the R-MCA and L-MCA at both 5 and 20 minutes (
P
<0.05).

Conclusions—

ECP induces marked changes in cerebral arterial waveforms and augmented peak diastolic and mean MCA flow velocities on TCD in 5 healthy subjects.
Education, Social Roles, and the Risk of Cardiovascular Disease Among Middle-Aged Japanese Women
Authors: Honjo Kaori , Iso Hiroyasu , Inoue Manami , Tsugane Shoichiro
Published: July 2008

Background and Purpose—

Little research has been conducted into variations in women’s health in relation to educational level and social roles in Japan. We sought to examine the effect of educational level on risk of cardiovascular disease and its modification by social roles at work and at home under the Japan Public Health Center-based Prospective Study (JPHC Study) Cohort I.

Methods—

We calculated the adjusted hazard ratios of educational level for cardiovascular disease incidence within a 12-year study of 20 543 Japanese women aged 40 to 59 without history of stroke or heart disease.

Results—

The respective age and area-adjusted hazard ratios for junior high school education and college or higher education compared to high school education were 1.63 (95% CI: 1.29, 2.06) and 1.41(95% CI: 0.96, 2.05) for total stroke, 2.20 (95% CI: 1.34, 3.60) and 2.20 (95% CI: 1.08, 4.48) for subarachnoid hemorrhage, and 1.90 (95% CI: 1.30, 2.76) and 1.60 (95% CI: 0.87, 2.93) for ischemic stroke. The U-shaped association with risk of total stroke was primarily observed for working women with single social roles at home. No association was found between educational level and risk of coronary heart disease or intraparenchymal hemorrhage.

Conclusions—

A potential benefit of multiple social roles was suggested for stroke risk reduction among highly educated working women.
Metabolic Downregulation
Authors: Yenari Midori , Kitagawa Kazuo , Lyden Patrick , Perez-Pinzon Miguel
Published: July 2008

Background and Purpose—The search for effective neuroprotectants remains frustrating, particularly with regard to specific pharmaceuticals. However, laboratory studies have consistently shown remarkable neuroprotection with 2 nonpharmacological strategies—therapeutic hypothermia and ischemic preconditioning. Recent studies have shown that the mechanism of protection underlying both of these treatments is correlated to downregulation of cellular and tissue metabolism. Thus, understanding the mechanisms underlying such robust protective effects could lead to appropriate translation at the clinical level. In fact, hypothermia is already being used at many centers to improve neurological outcome from cardiac arrest.

Methods—A systematic review of both topics is presented in terms of underlying pathophysiological mechanisms and application at the clinical level.

Results—Although the mechanisms of protection for both therapeutic strategies are multifold, both share features of downregulating metabolism. Both therapeutic strategies are robust neuroprotectants, but translating them to the clinical arena is challenging, though not impossible, and clinical studies have shown or suggest benefits of both treatments.

Conclusions—The strategy of metabolic downregulation should be further explored to identify effective neuroprotectants that can be easily applied clinically.
The Predictive Value of Left Atrial Size for Incident Ischemic Stroke and All-Cause Mortality in African Americans
Authors: Nagarajarao Harsha S. , Penman Alan D. , Taylor Herman A. , Mosley Thomas H. , Butler Kenneth , Skelton Thomas N. , Samdarshi Tandaw E. , Aru Giorgio , Fox Ervin R.
Published: July 2008

Background and Purpose—

The association between left atrial (LA) size, ischemic stroke, and death has not been well established in African Americans despite their disproportionately higher rates of stroke and cardiovascular mortality compared to non-Hispanic whites.

Methods—

For the analysis, participants in the Jackson cohort of the Atherosclerosis Risk in Communities Study were followed from the date of the echocardiogram in cycle three to the date of the first ischemic stroke event (or death) or to December 31, 2004 if no ischemic stroke event (or death) was detected.

Results—

There were 1886 participants in the study population (mean age 58.9 years, 65% women). Participants in the top quintile of LA diameter indexed to height (LA diameter/height; 2.57 to 3.55 cm/m) were more likely women, hypertensive, diabetic, and obese compared to those not in the top quintile. Over a median follow-up of 9.8 years for ischemic stroke and 9.9 years for all-cause mortality, there were 106 strokes and 242 deaths. In a multivariable model adjusting for traditional clinical risk factors, the top quintile of LA diameter/height was significantly related to ischemic stroke (HR 1.7; 95% CI: 1.1, 2.7) and all-cause mortality (HR 2.0; 95% CI: 1.5, 2.7). After further adjustment for left ventricular (LV) hypertrophy and low LV ejection fraction, the top quintile remained significantly related to all-cause mortality (HR 1.8; 95% CI: 1.3, 2.5).

Conclusions—

In this population-based cohort of African Americans, LA size was a predictor of all-cause mortality after adjusting for traditional cardiovascular risk factors, LV hypertrophy, and low LV ejection fraction.
Comparison of Primary Angioplasty With Stent Placement for Treating Symptomatic Intracranial Atherosclerotic Diseases
Authors: Siddiq Farhan , Vazquez Gabriela , Memon Muhammad Zeeshan , Suri M. Fareed K. , Taylor Robert A. , Wojak Joan C. , Chaloupka John C. , Qureshi Adnan I.
Published: July 2008

Background and Purpose—

We sought to compare the clinical outcomes between primary angioplasty and stent placement for symptomatic intracranial atherosclerosis.

Methods—

We retrospectively analyzed the clinical and angiographic data of 190 patients treated with 95 primary angioplasty procedures and 98 intracranial stent placements (total of 193 procedures) in 3 tertiary care centers. Stroke and combined stroke and/or death were identified as primary clinical end points during the periprocedural and follow-up period of 5 years. The rates of significant postoperative residual stenosis (≥50% of greater stenosis immediately after the procedure) and binary restenosis (≥50% stenosis at follow-up angiography within 3 years) were also compared. The comparative analysis was performed after adjusting for age, sex, and center.

Results—

Fourteen procedures in the angioplasty-treated group (15%) and 4 in the stent-treated group (4.1%) had significant postoperative residual stenosis (relative risk [RR]=2.8, 95% CI, 0.85 to 9.5,
P
=0.09, for the adjusted model). There were 3 periprocedural deaths (1.5%), 1 in the angioplasty group (1.1%) and 2 in the stent-treated group (2.0%) and 14 periprocedural strokes (7.3%), 7 periprocedural strokes in each group (7.4% and 7.1%, respectively; hazard ratio=1.1; 95% CI, 0.57 to 1.9,
P
=0.85). Angiographic follow-up was available for 134 procedures (66 angioplasty-treated and 68 stent-treated cases). Forty-eight procedures (36.1%) had evidence of binary restenosis (25 of 66 angioplasties, 23 of 68 stents,
P
=0.85). Binary restenosis-free survival at 12 months was 68% for the angioplasty-treated group and 64% for the stent-treated group. There was no difference in follow-up survival (stroke, or stroke and/or death) between the angioplasty-treated and the stent-treated groups (hazard ratio=0.54; 95% CI, 0.11 to 2.5,
P
=0.44 and hazard ratio=0.50; 95%, CI 0.17 to 1.5,
P
=0.22, respectively, after adjusting for age, sex, and center). The stroke- and/or death-free survival at 2 years for the angioplasty-treated group and the stent-treated group was 92±4% and 89±5%, respectively.

Conclusions—

Stent treatment for intracranial atherosclerosis may lower the rate of significant postoperative residual stenosis compared with primary angioplasty alone. No benefit of stent placement over primary angioplasty in reducing stroke or stroke and/or death could be identified in this study.
Long Term Postischemic Stroke Mortality in Diabetes
Authors: Kamalesh Masoor , Shen Jianzhao , Eckert George J.
Published: July 2008

Background and Purpose—

Recent data on stroke mortality in diabetics in the United States is lacking. We investigated trends in diabetes prevalence and stroke morality among diabetics in a large veteran cohort.

Methods—

The Patient Treatment File was used to identify all patients discharged from any Veterans hospital between October 1990 and September 1997 with a diagnosis of ischemic stroke (ICD-9-CM codes 434, 436) listed as primary diagnosis. Demographic, morbidity, and mortality data were recorded. Chi-square tests were used to examine differences between diabetics and nondiabetics, and
t
tests were used for continuous variables. Cox proportional hazards regression was used to examine the effects of diabetes (DM) on the survival times controlling for multiple covariates.

Results—

Of 48 733 ischemic stroke patients identified, 98% were male and 13 925 (25%) had DM. Mean age was similar between DM and non-DM (67.2 versus 67.5,
P
=NS). Prevalence of DM among stroke subjects increased from 25% to 31%. Charlson index >2 was much higher in DM (68.2% versus 47.9%,
P
<0.001). Mortality at 60 days and 1 year was similar in both groups (2.9 versus 2.7%,
P
=NS; 12.6 versus 13.1,
P
=NS). Kaplan-Meier survival plot showed that DM had shorter long term survival time (log-rank,
P
<0.001). Multivariate Cox proportional hazards regression showed a higher risk of death for diabetics (HR=1.15, 95% CI 1.11 to 1.19,
P
<0.001).

Conclusion—

Despite greater comorbidity, postacute ischemic stroke mortality at 60 days and 1 year is not different between subjects with and without DM. Long term mortality after stroke is much lower among DM than that reported in older studies.
On the Zonal Structure of the North Atlantic Oscillation and Annular Modes
Authors: Gerber Edwin P. , Vallis Geoffrey K.
Published: July 2008

The zonal structure and dynamics of the dipolar patterns of intraseasonal variability in the extratropical atmosphere—namely, the North Atlantic Oscillation (NAO) and the so-called annular modes of variability—are investigated in an idealized general circulation model. Particular attention is focused on the relationships linking the zonal structure of the stationary waves, synoptic variability (i.e., the storm tracks), and the zonal structure of the patterns of intraseasonal variability. Large-scale topography and diabatic anomalies are introduced to modify and concentrate the synoptic variability, establishing a recipe for a localized storm track. Comparison of the large-scale forcing, synoptic variability, and patterns of intraseasonal variability suggests a nonlinear relationship between the large-scale forcing and the variability. It is found that localized NAO-like patterns arise from the confluence of topographic and diabatic forcing and that the patterns are more localized than one would expect based on superposition of the responses to topography and thermal forcing alone.

The connection between the eddy life cycle of growth and decay and the localization of the intraseasonal variability is investigated. Both the termination of the storm track and the localization of the intraseasonal variability in the GCM depend on a difluent region of weak upper-level flow, where eddies break and dissipate rather than propagate energy forward through downstream development. The authors' interpretation suggests that the North Atlantic storm track and the NAO are two manifestations of the same phenomenon. Conclusions from the GCM study are critiqued by comparison with observations.
The Effects of Critical Layers on Residual Layer Turbulence
Authors: Tjernström Michael , Balsley Ben B. , Svensson Gunilla , Nappo Carmen J.
Published: July 2008

The authors report results of a study of finescale turbulence structure in the portion of the nocturnal boundary layer known as the residual layer (RL). The study covers two nights during the Cooperative Atmosphere–Surface Exchange Study 1999 (CASES-99) field experiment that exhibit significant differences in turbulence, as indicated by the observed turbulence dissipation rates in the RL. The RL turbulence sometimes reaches intensities comparable to those in the underlying stable boundary layer.

The commonly accepted concept of turbulence generation below critical values of the gradient Richardson number (Rig) is scale dependent: Ri values typically decrease with decreasing vertical scale size, so that critical Rig values (≈0.25) occur at vertical scales of only a few tens of meters. The very small scale for the occurrence of subcritical Ri poses problems for incorporating experimentally determined Rig -based methods in model closures in models with poor resolution.

There appear to be two distinct turbulence “regimes” in the RL: a very weak but ever-present background turbulence level with minimal temporal and spatial structure and a more intense intermittent regime during which turbulent intensity can approach near-surface nighttime turbulent intensities. It is hypothesized that the locally produced RL turbulence can be related to upward-propagating atmospheric gravity waves generated by flow over the low-relief terrain. The presence of critical layers in the RL, caused by wind turning with height, results in the generation of intermittent turbulence.
Aerodynamic Contrails: Phenomenology and Flow Physics
Authors: Gierens K. , Kärcher B. , Mannstein H. , Mayer B.
Published: July 2008

Aerodynamic contrails have been recognized for a long time although they appear sporadically. Usually one observes them under humid conditions near the ground, where they are short-lived phenomena. Aerodynamic contrails appear also at cruise levels where they may persist when the ambient atmosphere is ice-supersaturated. The present paper presents a theoretical investigation of aerodynamic contrails in the upper troposphere. The required flow physics are explained and applied to a case study. Results show that the flow over aircraft wings leads to large variations of pressure and temperature. Average pressure differences between the upper and lower sides of a wing are on the order of 50 hPa, which is a quite substantial fraction of cruise-level atmospheric pressures. Adiabatic cooling exceeds 20 K about 2 m above the wing in a case study shown here. Accordingly, extremely high supersaturations (exceeding 1000%) occur for a fraction of a second. The potential consequences for the ice microphysics are discussed. Because aerodynamic contrails are independent of the formation conditions of jet contrails, they form an additional class of contrails that might be complementary because they form predominantly in layers that are too warm for jet contrail formation.
Aerodynamic Contrails: Microphysics and Optical Properties
Authors: Kärcher B. , Mayer B. , Gierens K. , Burkhardt U. , Mannstein H. , Chatterjee R.
Published: July 2008

Aerodynamic contrails form when air flows across the wings of subsonic aircraft in cruise. During a short adiabatic expansion phase, high supersaturations trigger burstlike homogeneous ice formation on ambient liquid aerosol particles within a wing depth. Small particles freeze first because they equilibrate most rapidly. Ambient temperature is the key determinant of nascent aerodynamic contrail properties. Only above ∼232 K do they become visible (but optically thin). These temperatures are at the high end of those prevailing at tropical upper tropospheric flight levels of subsonic aircraft. In colder midlatitude conditions, aerodynamic contrails stay invisible and the very small ice particles formed quickly evaporate when exposed to small subsaturations, explaining why the formation of these contrails is rarely observed. After formation, aerodynamic contrails develop into contrail cirrus if air is supersaturated with respect to ice. This type of anthropogenic ice cloud adds to contrail cirrus derived from jet exhaust contrails and may become particularly important in the future because air traffic is projected to increase significantly in tropical and subtropical regions. Regardless of whether aerodynamically induced ice formation leads to persistent contrail cirrus, cruising aircraft may act as sources of potent heterogeneous ice nuclei by preactivating the insoluble fraction in atmospheric particle populations. Aerodynamic contrails and aerodynamically induced preactivation should therefore be studied experimentally and with global models to explore their potential to induce climate change.
The Relationship between Statistically Linear and Nonlinear Feedbacks and Zonal-Mean Flow Variability in an Idealized Climate Model
Authors: Kravtsov Sergey , Ten Hoeve John E. , Feldstein Steven B. , Lee Sukyoung , Son Seok-Woo
Published: July 2008

Simulations using an idealized, atmospheric general circulation model (GCM) subjected to various thermal forcings are analyzed via a combination of probability density function (PDF) estimation and spectral analysis techniques. Seven different GCM runs are examined, each model run being characterized by different values in the strength of the tropical heating and high-latitude cooling. For each model run, it is shown that a linear stochastic model constructed in the phase space of the ten leading empirical orthogonal functions (EOFs) of the zonal-mean zonal flow provides an excellent statistical approximation to the simulated zonal flow variability, which includes zonal index fluctuations, and quasi-oscillatory, poleward, zonal-mean flow anomaly propagation. Statistically significant deviations from the above linear stochastic null hypothesis arise in the form of a few anomalously persistent, or statistically nonlinear, flow patterns, which occupy particular regions of the model’s phase space. Some of these nonlinear regimes occur during certain phases of the poleward propagation; however, such an association is, in general, weak. This indicates that the regimes and oscillations in the model may be governed by distinct dynamical mechanisms.
Relationship between Tropical Easterly Waves and Precipitation during the North American Monsoon
Authors: Ladwig William C. , Stensrud David J.
Published: July 2008

Relationships between tropical easterly waves (TEWs) and precipitation over Mexico and the United States are examined during the North American monsoon (NAM). The National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis data are used to identify 137 TEWs that cross Mexico north of 20°N after monsoon onset over a 31-yr period from 1975 to 2005. Mean precipitation anomalies over two-day periods both before and after TEW passage are determined using Climate Prediction Center daily precipitation analyses. Results indicate that positive precipitation anomalies occur along the west coast of Mexico and extending into the west-central United States in association with TEW passage. Negative precipitation anomalies are found in the south-central United States. These precipitation anomaly patterns share many similarities to precipitation anomaly patterns previously defined in association with gulf surge events. On longer time scales, correlations between the total number of these northern TEWs crossing Mexico and 90-day monsoon period precipitation anomalies are also examined. An out-of-phase relationship is found between monsoon period precipitation anomalies in the southwestern and south-central United States, suggesting that increasing the number of northern TEWs crossing Mexico leads to enhanced monsoon period rainfall in Arizona and New Mexico and reduced monsoon period rainfall in Texas and Oklahoma. Thus, these northern TEWs likely play an important role in producing the distribution of precipitation throughout the NAM region and the south-central United States during the monsoon season, and extended-range predictions of northern TEW frequency may lead to improved seasonal rainfall anomaly forecasts in these regions.
An Observed Connection between the North Atlantic Oscillation and the Madden–Julian Oscillation
Authors: Lin Hai , Brunet Gilbert , Derome Jacques
Published: July 2008

Based on the bivariate Madden–Julian oscillation (MJO) index defined by Wheeler and Hendon and 25 yr (1979–2004) of pentad data, the association between the North Atlantic Oscillation (NAO) and the MJO on the intraseasonal time scale during the Northern Hemisphere winter season is analyzed. Time-lagged composites and probability analysis of the NAO index for different phases of the MJO reveal a statistically significant two-way connection between the NAO and the tropical convection of the MJO. A significant increase of the NAO amplitude happens about 5–15 days after the MJO-related convection anomaly reaches the tropical Indian Ocean and western Pacific region. The development of the NAO is associated with a Rossby wave train in the upstream Pacific and North American region. In the Atlantic and African sector, there is an extratropical influence on the tropical intraseasonal variability. Certain phases of the MJO are preceded by the occurrence of strong NAOs. A significant change of upper zonal wind in the tropical Atlantic is caused by a modulated transient westerly momentum flux convergence associated with the NAO.
Stochastic Forcing of Ocean Variability by the North Atlantic Oscillation
Authors: Chhak Kettyah C. , Moore Andrew M. , Milliff Ralph F.
Published: July 2008

At middle and high latitudes, the magnitude of stochastic wind stress forcing of the ocean by atmospheric variability on synoptic time scales (i.e., “weather” related variability) is comparable to that of the seasonal cycle. Stochastic forcing may therefore have a significant influence on the ocean circulation, climate, and ocean predictability. Here, the influence of stochastic forcing associated with the North Atlantic Oscillation on the subtropical gyre circulation of the North Atlantic is explored in an eddy-permitting quasigeostrophic framework. For the North Atlantic winds used in this study, the root-mean-square of the annual average Ekman pumping velocity of the seasonal cycle between 35° and 52°N is 1.3 × 10−7 m s−1, while the wintertime standard deviation of the stochastic component of the North Atlantic Oscillation over the same latitude band is 2.2 × 10−7 m s−1. Significant stochastically induced variability in the ocean circulation occurs near the western boundary region and along the western margins of the abyssal plains associated with vortex stretching, energy release from the mean flow, and the generation of topographic Rossby waves. Variability arises from a combination of two effects, depending on the measure of variance used: growth of unstable modes of the underlying circulation and modal interference resulting from their nonnormal nature, which dominates during the first 10 days or so of perturbation growth. Near the surface, most of the variability is associated with large-scale changes in the barotropic circulation, although more than 20% of the energy and enstrophy variability is associated with small-scale baroclinic waves. In the deep ocean, much of the stochastically induced variability is apparently due to topographic Rossby wave activity along the continental rise and ocean ridges. Previous studies have demonstrated that rectification of topographic Rossby wave–induced circulations in the western North Atlantic may contribute to the western boundary current recirculation zones. The authors suggest that a source of topographic Rossby wave energy, significant enough to rectify the mean ocean circulation, may arise from stochastic forcing by large-scale atmospheric forcing, such as the North Atlantic Oscillation and other atmospheric teleconnection patterns.
Unification of the Anelastic and Quasi-Hydrostatic Systems of Equations
Authors: Arakawa Akio , Konor Celal S.
Published: July 2008

A system of equations is presented that unifies the nonhydrostatic anelastic system and the quasi-hydrostatic compressible system for use in global cloud-resolving models. By using a properly defined quasi-hydrostatic density in the continuity equation, the system is fully compressible for quasi-hydrostatic motion and anelastic for purely nonhydrostatic motion. In this way, the system can cover a wide range of horizontal scales from turbulence to planetary waves while filtering vertically propagating sound waves of all scales. The continuity equation is primarily diagnostic because the time derivative of density is calculated from the thermodynamic (and surface pressure tendency) equations as a correction to the anelastic continuity equation. No reference state is used and no approximations are made in the momentum and thermodynamic equations. An equation that governs the time change of total energy is also derived. Normal-mode analysis on an f plane without the quasigeostrophic approximation and on a midlatitude β plane with the quasigeostrophic approximation is performed to compare the unified system with other systems. It is shown that the unified system reduces the westward retrogression speed of the ultra-long barotropic Rossby waves through the inclusion of horizontal divergence due to compressibility.
High Oil Prices: Implications and Prospects
Authors: Weale Martin
Published: July 2008

The sharp rise in the real price of oil has taken it up to or above the levels seen after the second oil crisis of the late 1970s (depending on the currency considered) and has been, to say the least, somewhat disruptive to a world which had anticipated relatively cheap oil, probably for the indefinite future. At the very least, it is hard to imagine that some major consuming countries would have saved as little as they did, had they given proper attention to oil's status as an exhaustible resource. In this commentary the current situation is viewed from that perspective. The short-term impact of high oil prices is discussed on pp. 34–8.
Robust growth and rising inflation in East Asia
Authors: Pomerantz Olga
Published: July 2008

Output growth in the economies of East Asia, including Japan, remained firm in the opening months of this year, in line with relatively resilient GDP growth in the US and in Europe. Hong Kong's economy continued to boom despite the cooling-off of China's economy. Real GDP grew at an annual rate of 7.2 per cent, faster than the 6.9 per cent growth in the final quarter of last year, supported by exports which have benefited from the effective devaluation that has come from the fixed link to the US dollar. Domestic demand continued to expand briskly, registering a 7.0 per cent gain on an annual basis. In South Korea, domestic demand growth decelerated somewhat to 3.6 per cent per annum in the first quarter, but strong export performance meant that the economy as a whole grew by a respectable 5.7 per cent on an annual basis. Elsewhere, strong credit growth and rampant infrastructure spending have been supporting domestic demand growth across the region in general. We continue to expect output growth to moderate somewhat but to remain healthy this year in much of East Asia and Australia. Following strong output growth of 3.6 per cent in the first quarter, Australian GDP is forecast to expand by about 3¼ per cent per annum this year, down from 3.9 per cent recorded last year. Korean growth is expected to accelerate partly in response to the recent 10 per cent fall in the effective exchange rate. We expect growth to exceed 6 per cent this year and inflation is expected to accelerate in response to high oil prices and the weak exchange rate. Chinese growth is forecast to moderate only slightly this year, as the last minute preparations for the Beijing Olympics and the event itself are expected to provide a boost to domestic demand in the second half of the year. Output growth in Taiwan is likewise expected to moderate to about 4¾ per cent on an annual basis.
The Oil Intensity of Output
Authors: Barrell Ray , Kirby Simon , Liadze Iana
Published: July 2008

Since our last forecast in April 2008 there have been further increases in oil prices, as is illustrated in figure 1, which tracks oil price projections in our forecasts this year, and compares them to the projection we made in January and July 2007. Over the past eighteen months oil prices have risen from around $60 per barrel to a currently projected level of $123 in 2009. Oil prices have recently reached a peak of $145.6 a barrel before falling back to around $134. Our projection for the short term is based on those of the US Energy Information Agency and uses information from forward markets as well as an evaluation of supply conditions. In the longer term we presume that real oil prices will rise in line with the real interest rate, as is discussed on pp. 4–7 of this Review. This note looks at the impacts of recent increases in oil prices on the path for real wages by investigating the share of fossil fuels in costs. It also evaluates the impact of the rise in prices since our last forecast, and investigates the impact on oil prices of the growth in demand outside the OECD.
Consumption, Housing Wealth and Financial Crises
Authors: Barrell Ray , Kirby Simon
Published: July 2008

This note reviews recent Institute work on the factors that might affect the future evolution of consumption. Drawing on Barrell and Davis (2007), it discusses the evidence for the effects of housing wealth on consumption, and shows that there has been strong and well supported evidence for a link for some time. This evidence suggests that a fall in house prices will cause consumption growth to slow. The discussion also covers evidence from Barrell, Davis and Pomerantz (2006) on the effects of financial crises on consumption behaviour. They suggest that there are large and significant negative effects on consumption during banking crises that are over and above the effects on consumption of the crisis-induced changes in income and wealth. Much of this work is embedded in our structural model, NiGEM, and it is possible to estimate the effects of house price declines and financial crises on consumption and income using the model. The note also gives a set of ready reckoners for the impacts of house price declines on output and of a given associated fall in the level of housing wealth on the level of consumption.
A novel quantum ant colony optimization algorithm and its application to fault diagnosis
Authors: Ling Wang  , Qun Niu  , Minrei Fei
Published: July 2008

Fault detection in chemical production processes is difficult because of the amount of data that needs to be analysed and the absence of fault data. This paper uses support vector machines (SVMs) to diagnose faults, as it fits the small sample problem. To eliminate system disturbances and noise from the high levels of data, it then combines SVMs with a novel quantum ant colony optimization (QACO) algorithm to select the fault features. The proposed method is then tested using the benchmark Tennessee Eastman Process and shown to be effective. In particular, it is demonstrated that QACO and SVMs can find the essential fault variables exactly, and will greatly improve the fault diagnosis performance of SVMs for a complex chemical process.
Stability analysis of a double integrator swarm model related to position and velocity
Authors: Dan Jin  , Lixin Gao
Published: July 2008

In this paper, we propose a biologically inspired, continuous double integrator model based on individual Newton's law in an n-dimensional space. The double integrator model is related to positions and velocities of individuals. We discuss three cases of the attraction/repulsion functions, which are odd for the attractive force and repulsion force taking effect in opposite directions, and we obtain the swarm size and ultimate motions for cohesion in every case. Stability analysis and numerical simulations are also presented to demonstrate the effectiveness of our model.
A new method for short-term electricity load forecasting
Authors: Wang Jing-Min , Wang Li-Ping
Published: July 2008

Accurate forecasting of short-term electricity load is an important issue in the electricity industry. This paper proposes a new forecasting model by integrating the support vector machines (SVMs) forecasting technique and rough sets (RSs) with reduced attributes using evolutionary algorithms (EAs). Simulation results show that this new model can improve the prediction accuracy, speed the convergence and require less computational effort in comparison with another two methods, namely the traditional SVM model and a model combining the SVMs and simulated annealing algorithms (SVMSA). This improvement is related to fact that the RS techniques can reduce the SVM input variables and improve the convergence.
A hybrid approach to 3D arm motion tracking
Authors: Yaqin Tao  , Huosheng Hu
Published: July 2008

This paper presents a hybrid approach to 3D arm motion tracking for tele-rehabilitation applications. A particle filter (PF) algorithm is adopted in the proposed system to fuse data from inertial and visual sensors in a probabilistic manner. Multi-modal distributions of system states are propagated based on a 'factor sampling' technique. To avoid the problem of particle degeneracy in conventional PF algorithms, two strategies are adopted in our system, namely state-space pruning and an arm physical geometry constraint. Experimental results show that the proposed PF framework outperforms other fusion methods and tracking results are accurate in comparison to the ground truth provided by a commercial mark-based motion tracking system.
Modified Likelihood-Based Item Fit Statistics for the Generalized Graded Unfolding Model
Authors: Roberts James S.
Published: July 2008

Orlando and Thissen (2000) developed an item fit statistic for binary item response theory (IRT) models known as S - X2. This article generalizes their statistic to polytomous unfolding models. Four alternative formulations of S - X2 are developed for the generalized graded unfolding model (GGUM). The GGUM is a unidimensional IRT model for unfolding polytomous responses. It yields single-peaked, nonmonotonic item characteristic curves that predict a higher item score to the extent that an individual is located close to an item on the underlying latent continuum. A simulation was performed to examine the characteristics of these new item fit indices under the GGUM, as well as a traditional likelihood ratio χ2 test ( G2). All variants of S - X2 exhibited reasonable Type I error rates, but that for G2 was more erratic. The new indices exhibited variable power to detect misfit. Two new item fit tests are recommended for use based on simulation results.
Multidimensional Scoring of Abilities: The Ordered Polytomous Response Case
Authors: de la Torre Jimmy
Published: July 2008

Recent work has shown that multidimensionally scoring responses from different tests can provide better ability estimates. For educational assessment data, applications of this approach have been limited to binary scores. Of the different variants, the de la Torre and Patz model is considered more general because implementing the scoring procedure does not require prior knowledge of the correlational structure of the abilities, and existing item parameter estimates from traditional item response theory models can be utilized. This article extends the application of this method to data scored on ordered polytomous scales. A simulation study systematically examines how improvement in ability estimates is affected by factors such as the number of score categories, number of tests, test length, and correlation between abilities. Application of the method is illustrated using real data. Estimates of the abilities and the correlational structure are obtained using the Markov chain Monte Carlo method.
Are Mothers Really “Gatekeepers” of Children?
Authors: Sano Yoshie , Richards Leslie N. , Zvonkovic Anisa M.
Published: July 2008

Guided by symbolic interactionism, this qualitative study based on interviews with 83 rural mothers investigated mothers' perceptions of nonresident fathers' involvement in low-income families. Contrary to some fathers' claims that mothers “gatekeep” their access to children, the majority of mothers in our study wanted increased father involvement. The mothers' desire for active father–child interaction was not dampened by their frustration at the lack or irregularity of child support payment, which mothers tended to accept, given the lack of economic opportunities in rural communities. Despite their wishes to promote father–child contact, mothers also experienced frustration and distrust toward former partners when they perceived that the fathers were not fulfilling their expected parental roles. This study demonstrates that mothers' actions, which may be interpreted as gatekeeping by the fathers, are often not intended to discourage father involvement but rather are meant to negotiate more acceptable father behavior.
African American Students and College Choice
Authors: Muhammad Crystal Gafford
Published: July 2008

Misinformation in the African American community regarding college costs, access, and the benefits of a college education abound. Counseling from a trustworthy, supportive school counselor can make a difference in stemming African American talent loss, especially among young Black men. Using the 1988 National Educational Longitudinal Survey, the author finds that African American students' understanding of their counselors' expectations for their future education positively influences college predisposition at a magnitude comparable to fatherly support. Implications for principals and school counselor assignments are addressed.
Evaluating and Improving the Quality of Teacher Collaboration
Authors: Gajda Rebecca , Koliba Christopher J.
Published: July 2008

Teacher collaboration is an essential element of substantive school change for which principals have responsibility for cultivating. As such, it is becoming increasingly important for school leaders to employ models of supervision that focus on the performance and improvement of collective teacher behavior. In this article, the authors present a field-tested, action-research leadership framework for evaluating the quality and improving the performance of teacher collaboration at the secondary school level.
Supportive Schooling
Authors: Calaff Kristin Percy
Published: July 2008

Given the challenges of a culturally and linguistically diverse student body, one exemplary high school has developed supportive schooling practices that provide academic rigor and access for all students while embracing their linguistic and cultural identities. This ethnographic study documents how this school contributed to the college preparation of nine Latino immigrant students. Implications also address the need for partnerships with university and community resources that assist students and families in the college preparation process.
Health Behavior in Mexican Pregnant Women with a History of Violence
Authors: Quelopana Ana M. , Champion Jane Dimmitt , Salazar Bertha C.
Published: July 2008

This study examines the association between history of violence, attitudes toward pregnancy, and initiation of prenatal care (PNC). Pregnant women receiving their first PNC visit at a public prenatal clinic in Monterrey, Mexico, were enrolled in the study. Structured interviews collected information concerning demographics, reproductive history, current pregnancy, attitudes toward pregnancy, history of violence, and perceived barriers and benefits of PNC. Results showed that 35% of participants reported violence. A current or previous partner was the most common perpetrator. Of women experiencing abuse, 47% reported that abuse was ongoing during the current pregnancy. More women reporting violence were unmarried, did not live with a partner, and reported a lower monthly income. An experience of violence was associated with initiation of PNC, number of pregnancies, perception of barriers, and negative attitudes toward pregnancy. This issue should be emphasized in recognition of the important role that nurses and midwives have regarding violence.
Theological History and the Legitimacy of the Modern Social Sciences: Considerations on the Work of Hans Blumenberg
Authors: Harrington Austin
Published: July 2008

This article explores the much neglected work of the German philosopher and cultural theorist Hans Blumenberg, a figure still relatively little known in the Anglophone world. The thesis is defended that Blumenberg's conception of The Legitimacy of the Modern Age (1966) offers valuable resources for addressing some important questions about the philosophical self-understanding of the modern social sciences in relation to theological and religious sources of thought and language. The article begins with an assessment of the contemporary relevance of Blumenberg's critique of the idea of modern scientific culture as a merely `secularized form' of theological thinking. This critique is then compared with Blumenberg's account of the relationship of theoretico-scientific inquiry to mythological consciousness in his second major philosophical monograph of 1979, Work on Myth. The article concludes with a range of reflections on ways in which Blumenberg's work helps us understand how certain explanatory constructs and devices employed in the modern social sciences can be said to incorporate, assimilate, and at the same time critically transform figures of thought and language that display a mythic, religious and theological context of historical origination, provenance or genealogy.
Sovereignty, Governance and the Political: The Problematic of Foucault
Authors: Singer Brian C. J. , Weir Lorna
Published: July 2008

Contemporary Foucauldian research assimilates the political with governance. This formulation dates to Foucault's emphasis on the significance of the anti-Machiavellians in introducing the concept of governance into political theory. Returning to Machiavelli, we argue that early modern political theory was instead characterized by the simultaneous problematization of ruler and ruled, and the co-constitution of sovereignty and governance. We then outline the relation of ruler and ruled in the political structure of the democratic sovereign. Concepts of both sovereignty and governance are necessary to theorize the political in modernity, including the dangers that arise from fusing sovereignty and governance, as occurred during the Nazi period in Germany, when the distinction between the sovereign people and the governed population was conflated.
Academic Entrepreneurship and the Creative Economy
Authors: Peters Michael A. , Besley Tina (A. C.)
Published: July 2008

This article explores the relationships between several notions: the `creative economy'; New Growth Theory and the primacy of ideas; academic entrepreneurship; and the new paradigm of cultural production. Broadly conceptualized, the creative economy links the primacy of ideas in both arts and sciences in a more embedded and social framework of entrepreneurship which positions education as central, since its institutions are the primary knowledge institutions that provide the conditions for the transmission and development of new ideas. Entrepreneurship develops within networks that use new information and communication technologies. The role of the arts, humanities and social sciences becomes re-profiled as crucial in the generation of new ideas within the creative economy, moving discussion and analysis away from a single focus on Science, Technology, Engineering and Mathematics (STEM) and the hard sciences such that the redesign of institutional/academic environments is necessary in order to capitalize on ideas and move from creativity to systems of innovation.