Relationship of blood pressure, antihypertensive therapy, and outcome in ischemic stroke treated with intravenous thrombolysis: retrospective analysis from Safe Implementation of Thrombolysis in Stroke-International Stroke Thrombolysis Register (SITS-ISTR)

<p><b>Background and Purpose:</b> The optimal management of blood pressure (BP) in acute stroke remains unclear. For ischemic stroke treated with intravenous thrombolysis, current guidelines suggest pharmacological intervention if systolic BP exceeds 180 mm Hg. We determined retrospectively the association of BP and antihypertensive therapy with clinical outcomes after stroke thrombolysis.</p> <p><b>Methods:</b> The SITS thrombolysis register prospectively recorded 11 080 treatments from 2002 to 2006. BP values were recorded at baseline, 2 hours, and 24 hours after thrombolysis. Outcomes were symptomatic (National Institutes of Health Stroke Scale score deterioration ≥4) intracerebral hemorrhage Type 2, mortality, and independence at (modified Rankin Score 0 to 2) 3 months. Patients were categorized by history of hypertension and antihypertensive therapy within 7 days after thrombolysis: Group 1, hypertensive treated with antihypertensives (n=5612); Group 2, hypertensive withholding antihypertensives (n=1573); Group 3, without history of hypertension treated with antihypertensives (n=995); and Group 4, without history of hypertension not treated with antihypertensives (n=2632). For 268 (2.4%) patients, these data were missing. Average systolic BP 2 to 24 hours after thrombolysis was categorized by 10-mm Hg intervals with 100 to 140 used as a reference.</p> <p><b>Results:</b> In multivariable analysis, high systolic BP 2 to 24 hours after thrombolysis as a continuous variable was associated with worse outcome (P<0.001) and as a categorical variable had a linear association with symptomatic hemorrhage and a U-shaped association with mortality and independence with systolic BP 141 to 150 mm Hg associated with most favorable outcomes. OR (95% CI) from multivariable analysis showed no difference in symptomatic hemorrhage (1.09 [0.83 to 1.51]; P=0.58) and independence (1.03 [0.93 to 1.10]; P=0.80) but lower mortality (0.82 [0.73 to 0.92]; P=0.0007) for Group 1 compared with Group 4. Group 2 had a higher symptomatic hemorrhage (1.86 [1.34 to 2.68]; P=0.0004) and mortality (1.62 [1.41 to 1.85]; P<0.0001) and lower independence (0.89 [0.80 to 0.99]; P=0.04) compared with Group 4. Group 3 had similar results as Group 1.</p> <p><b>Conclusions:</b> There is a strong association of high systolic BP after thrombolysis with poor outcome. Withholding antihypertensive therapy up to 7 days in patients with a history of hypertension was associated with worse outcome, whereas initiation of antihypertensive therapy in newly recognized moderate hypertension was associated with a favorable outcome.</p&gt

MEASURING HISTORICAL RISK IN QUARTERLY MILK PRICES

Various methods have been used to estimate risk indices with historical data. An industry perception of increasing milk price risk over time provides a standard for evaluating several techniques used to measure historical risk. Risk measures from a regression model and an ARIMA model were consistent with the perception of increasing risk.Risk and Uncertainty,

Dynamical Origin of Extrasolar Planet Eccentricity Distribution

We explore the possibility that the observed eccentricity distribution of extrasolar planets arose through planet-planet interactions, after the initial stage of planet formation was complete. Our results are based on ~3250 numerical integrations of ensembles of randomly constructed planetary systems, each lasting 100 Myr. We find that for a remarkably wide range of initial conditions the eccentricity distributions of dynamically active planetary systems relax towards a common final equilibrium distribution, well described by the fitting formula dn ~ e exp[-1/2 (e/0.3)^2] de. This distribution agrees well with the observed eccentricity distribution for e > 0.2, but predicts too few planets at lower eccentricities, even when we exclude planets subject to tidal circularization. These findings suggest that a period of large-scale dynamical instability has occurred in a significant fraction of newly formed planetary systems, lasting 1--2 orders of magnitude longer than the ~1 Myr interval in which gas-giant planets are assembled. This mechanism predicts no (or weak) correlations between semimajor axis, eccentricity, inclination, and mass in dynamically relaxed planetary systems. An additional observational consequence of dynamical relaxation is a significant population of planets (>10%) that are highly inclined (>25deg) with respect to the initial symmetry plane of the protoplanetary disk; this population may be detectable in transiting planets through the Rossiter-McLaughlin effect.Comment: Accepted to ApJ, conclusions updated to reflect the current observational constraint

Gravitons and Lightcone Fluctuations II: Correlation Functions

A model of a fluctuating lightcone due to a bath of gravitons is further investigated. The flight times of photons between a source and a detector may be either longer or shorter than the light propagation time in the background classical spacetime, and will form a Gaussian distribution centered around the classical flight time. However, a pair of photons emitted in rapid succession will tend to have correlated flight times. We derive and discuss a correlation function which describes this effect. This enables us to understand more fully the operational significance of a fluctuating lightcone. Our results may be combined with observational data on pulsar timing to place some constraints on the quantum state of cosmological gravitons.Comment: 16 pages and two figures, uses eps

Negative Energy Density States for the Dirac Field in Flat Spacetime

Negative energy densities in the Dirac field produced by state vectors that are the superposition of two single particle electron states are examined. I show that for such states the energy density of the field is not bounded from below and that the quantum inequalities derived for scalar fields are satisfied. I also show that it is not possible to produce negative energy densities in a scalar field using state vectors that are arbitrary superpositions of single particle states.Comment: 11 pages, LaTe

A New Generation Gap? Some thoughts on the consequences of increasingly early ICT first contact

One possible consequence of ICT’s rapid rise will be a new ‘generation gap’ arising from differing perceptions of the learning technologies. The nature, causes and consequences of this gap are of interest to educational practitioners and policymakers. This paper uses data from an ongoing project together with a synopsis of research to describe the ICT-based generation gap that currently exists between students and their teachers and parents. It is argued that this gap may exist between students differing in age by as little as five years. Results from a related project exploring Networked Information and Communication Literacy Skills (NICLS), are used to introduce a discussion on the nature of any skills gap that must be addressed in the light of this generation gap

Quantum Inequalities on the Energy Density in Static Robertson-Walker Spacetimes

Quantum inequality restrictions on the stress-energy tensor for negative energy are developed for three and four-dimensional static spacetimes. We derive a general inequality in terms of a sum of mode functions which constrains the magnitude and duration of negative energy seen by an observer at rest in a static spacetime. This inequality is evaluated explicitly for a minimally coupled scalar field in three and four-dimensional static Robertson-Walker universes. In the limit of vanishing curvature, the flat spacetime inequalities are recovered. More generally, these inequalities contain the effects of spacetime curvature. In the limit of short sampling times, they take the flat space form plus subdominant curvature-dependent corrections.Comment: 18 pages, plain LATEX, with 3 figures, uses eps

Gravitational vacuum polarization III: Energy conditions in the (1+1) Schwarzschild spacetime

Building on a pair of earlier papers, I investigate the various point-wise and averaged energy conditions for the quantum stress-energy tensor corresponding to a conformally-coupled massless scalar field in the in the (1+1)-dimensional Schwarzschild spacetime. Because the stress-energy tensors are analytically known, I can get exact results for the Hartle--Hawking, Boulware, and Unruh vacua. This exactly solvable model serves as a useful sanity check on my (3+1)-dimensional investigations wherein I had to resort to a mixture of analytic approximations and numerical techniques. Key results in (1+1) dimensions are: (1) NEC is satisfied outside the event horizon for the Hartle--Hawking vacuum, and violated for the Boulware and Unruh vacua. (2) DEC is violated everywhere in the spacetime (for any quantum state, not just the standard vacuum states).Comment: 7 pages, ReV_Te