Behavioral nudges in Facebook ads reached nearly 15 million people across six diverse countries and, consequently, many thousands took the step of navigating to governments' vaccine signup sites. However, none of the treatment ads caused significantly more vaccine signup intent than placebo uniformly across all countries. Critically, reporting the descriptive norm that 87% of people worldwide had either been vaccinated or planned vaccination-social proof-did not meaningfully increase vaccine signup intent in any country and significantly backfired in Taiwan.
View Article and Find Full Text PDFWhile machine coding of data has dramatically advanced in recent years, the literature raises significant concerns about validation of LLM classification showing, for example, that reliability varies greatly by prompt and temperature tuning, across subject areas and tasks-especially in "zero-shot" applications. This paper contributes to the discussion of validation in several different ways. To test the relative performance of supervised and semi-supervised algorithms when coding political data, we compare three models' performances to each other over multiple iterations for each model and to trained expert coding of data.
View Article and Find Full Text PDFPerceptions of social norms can have downstream consequences for attitudes and behaviors, especially when it comes to the acceptance of marginalized groups. While interventions focusing on social norms may boost tolerance, few studies test whether variations in norm communication affect individuals' perceptions. Thus, in this paper, we test the effectiveness of three communicative aspects-valence framing (Experiments 1-3), point of view (Experiment 1), and group centrism (Experiment 3)-in shifting perceptions of social norms.
View Article and Find Full Text PDFObjective: Acute traumatic subdural hematoma complicated by brain parenchymal injury is associated with a 60 to 90% mortality rate. Early surgical evacuation of the mass lesion is essential for a favorable outcome, but the severity of the underlying brain injury determines the outcome, even when surgery has been prompt. The purpose of this study was to analyze tissue biochemical patterns in the brain underlying an evacuated acute subdural hematoma to identify a characteristic pattern of changes that might indicate evolving brain injury.
View Article and Find Full Text PDFObjectives: Increasing PaO2 can increase brain tissue PO2 (PbtO2). Nevertheless, the small increase in arterial O2 content induced by hyperoxia does not increase O2 delivery much, especially when cerebral blood flow (CBF) is low, and the effectiveness of hyperoxia as a therapeutic intervention remains controversial. The purpose of this study was to examine the role of regional (r)CBF at the site of the PO2 probe in determining the response of PbtO2 to induced hyperoxia.
View Article and Find Full Text PDFPurpose Of Review: This review describes recent advances in multimodal neuromonitoring of patients following severe head injury during the period from 2001 to 2002.
Recent Findings: Monitoring intracranial pressure is considered a standard part of therapy despite a lack of randomized studies comparing patients with and without intracranial pressure monitoring. Jugular oximetry and brain tissue oxygen pressure monitoring are being used more frequently as part of a treatment protocol.
The authors report the use of percutaneous transpedicular vertebroplasty performed using polymethylmethacrylate (PMMA) in two patients. These men (53 and 57 years old) had previously undergone open surgery and posterior instrumentation to treat myelomatous compression fractures. Both patients presented with acute back pain that manifested after minor activities.
View Article and Find Full Text PDFIntroduction: Dynamic testing of cerebral pressure autoregulation is more practical than static testing for critically ill patients. The process of cuff deflation is innocuous in the normal subject, but the systemic and cerebral effects of cuff deflation in severely head-injured patients have not been studied. The purposes of this study were to examine the physiological effects of cuff deflation and to study their impact on the calculation of autoregulatory index (ARI).
View Article and Find Full Text PDFObjective And Importance: Delineation of cerebral white matter tracts using MR tractography adds essential information for planning intracranial surgery. Integrating tractography with intraoperative neuronavigation may reduce the likelihood of new neurological deficits after surgery done to remove tumors adjacent to the projection fibers of eloquent cortex. We report the utility of such integration for the resection of deep (paraventricular) tumors.
View Article and Find Full Text PDFThis review focuses on recent advances in the treatment of traumatic brain injury (TBI) during 2004 and 2005. Injured brain is a very heterogeneous structure, significantly evolving over time. Implementation of multimodal neuromonitoring will certainly provide more insights into pathophysiology of TBI.
View Article and Find Full Text PDFObjective: Induced hypertension is commonly used to improve cerebral perfusion, but this treatment may have the deleterious side effect of raising intracranial pressure (ICP). We tested the hypothesis that dynamic pressure autoregulation testing could identify patients who might develop increased ICP during induced hypertension.
Methods: Twenty-two studies were performed in 21 patients.
Background: It is controversial whether a low cerebral blood flow (CBF) simply reflects the severity of injury or whether ischemia contributes to the brain's injury. It is also not clear whether posttraumatic cerebral hypoperfusion results from intracranial hypertension or from pathologic changes of the cerebral vasculature. The answers to these questions have important implications for whether and how to treat a low CBF.
View Article and Find Full Text PDFPurpose: The epidermal growth factor receptor (EGFR) is overexpressed in approximately 50% to 60% of glioblastoma multiforme tumors, and the most common EGFR mutant, EGFRvIII, is expressed in 24% to 67% of cases. We sought to determine whether glioblastoma multiforme expression of either overexpressed wild-type EGFR or the mutant EGFRvIII is an independent predictor of overall patient survival.
Experimental Design: Glioblastoma multiforme patients (n = 196) underwent a > or =95% volumetric tumor resection followed by conformal radiation.
Arterial hypotension and intracranial hypertension are detrimental to the injured brain. Although artificial elevation of cerebral perfusion pressure (CPP) has been advocated as a means to maintain an adequate cerebral blood flow (CBF), the optimal CPP for the treatment of severe traumatic brain injury (TBI) remains unclear. In addition, CBF evolves significantly over time after TBI, and CBF may vary considerably in patient to patient.
View Article and Find Full Text PDFObjective: Acute traumatic subdural hematoma complicated by brain parenchymal injury is associated with a 60 to 90% mortality rate. Early surgical evacuation of the mass lesion is essential for a favorable outcome, but the severity of the underlying brain injury determines the outcome, even when surgery has been prompt. The purpose of this study was to analyze tissue biochemical patterns in the brain underlying an evacuated acute subdural hematoma to identify a characteristic pattern of changes that might indicate evolving brain injury.
View Article and Find Full Text PDFBackground: Carcinoid tumors rarely metastasize to the brain. The objectives of the current study were to assess the frequency of brain metastasis from carcinoid tumors, determine correlates of survival, and describe treatment modalities and their outcomes.
Methods: Between January 1977 and December 2003, 1633 patients with a carcinoid tumor were registered at The University of Texas M.
The purpose of this study was to compare the effects of L-arginine and tetrahydrobiopterin administration on post-traumatic cerebral blood flow (CBF) and tissue levels of NO in injured brain tissue. Rats were anesthetized with isoflurane. Mean blood pressure, intracranial pressure, cerebral blood flow using laser Doppler flowmetry (LDF) and brain tissue nitric oxide (NO) concentrations were measured prior to, and for 2 h after a controlled cortical impact injury.
View Article and Find Full Text PDFThe purpose of this study was to examine the patterns of change in microdialysate concentrations of glucose, lactate, pyruvate, and glutamate in the brain during periods of hypoxia/ischemia identified by monitoring brain tissue pO2 (PbtO2). Of particular interest was a better understanding of what additional information could be obtained by the microdialysis parameters that was not available from the PbtO2. Fifty-seven patients admitted with severe traumatic brain injury who had placement of both a brain tissue pO2 (PbtO2) and microdialysis probe were studied.
View Article and Find Full Text PDFNitric oxide (NO) is a gaseous chemical messenger which has functions in the brain in a variety of broad physiological processes, including control of cerebral blood flow, interneuronal communications, synaptic plasticity, memory formation, receptor functions, intracellular signal transmission, and release of neurotransmitters. As might be expected from the numerous and complex roles that NO normally has, it can have both beneficial and detrimental effects in disease states, including traumatic brain injury. There are two periods of time after injury when NO accumulates in the brain, immediately after injury and then again several hours-days later.
View Article and Find Full Text PDFTraumatic brain injury causes a reduction in cerebral blood flow, which may cause additional damage to the brain. The purpose of this study was to examine the role of nitric oxide produced by endothelial nitric oxide synthase (eNOS) in these vascular effects of trauma. To accomplish this, cerebral hemodynamics were monitored in mice deficient in eNOS and wild-type control mice that underwent lateral controlled cortical impact injury followed by administration of either L-arginine, 300 mg/kg, or saline at 5 min after the impact injury.
View Article and Find Full Text PDFJ Cereb Blood Flow Metab
May 2003
Nitric oxide (NO) has important regulatory functions within the central nervous system. NO is oxidized in vivo to nitrate and nitrite (NO(x)). Measurement of these products gives an index of NO production.
View Article and Find Full Text PDFObjective: Hypodense lesions identified on computed tomographic (CT) scans are often assumed to indicate ischemia. The purpose of this study was to investigate regional cerebral blood flow (rCBF) in hypodense areas of the brain after severe traumatic brain injury.
Methods: CBF was measured by stable xenon-enhanced CT scans.
Object: The purpose of this study was to evaluate the extent and timing of impairment of cerebral pressure autoregulation after severe head injury.
Methods: In a prospective study of 122 patients with severe head trauma (median Glasgow Coma Scale Score 6), dynamic tests of pressure autoregulation were performed every 12 hours during the first 5 days postinjury and daily during the next 5 days. The autoregulatory index ([ARI] normal value 5 +/- 1.