Then and Now: An Analysis of Broad-based Merit Aid Initial Eligibility Policies after Twenty Years

Using Hall’s framework of policy changes, we sought to document and classify changes in initial eligibility and award provisions of broad-based merit aid scholarship programs at inception and present day. Our analysis revealed five first-order changes, two second-order changes, and only one third order change. Although the policy settings, instruments, and goals remained static in five states, the scholarship dollars in four of them have not kept up with increases in overall cost of attendance

Resonance between Noise and Delay

We propose here a stochastic binary element whose transition rate depends on its state at a fixed interval in the past. With this delayed stochastic transition this is one of the simplest dynamical models under the influence of ``noise'' and ``delay''. We demonstrate numerically and analytically that we can observe resonant phenomena between the oscillatory behavior due to noise and that due to delay.Comment: 4 pages, 5 figures, submitted to Phys.Rev.Lett Expanded and Added Reference

Case Report: Hemorrhage into an Occult Spinal Ependymoma after Epidural Anesthesia

Epidural anesthesia is a procedure which is well tolerated and has a low incidence of adverse events. In performing caesarean sections, regional anesthesia (spinal or epidural) is the preferred modality for anesthetic delivery. Although rare with continuous epidural anesthesia, epidural hematomas have been reported to occur with an incidence between 1:150,000 and 1:190,00010. An underlying bleeding diathesis has been implicated as a causative factor. We present the sixth reported case of hemorrhage into an occult intradural neoplasm after spinal or epidural anesthesia. Similar lesions have not been reported in the recent spine literature

Anatomical relationships of the anterior blood vessels to the lower lumbar intervertebral discs: analysis based on magnetic resonance imaging of patients in the prone position.

BACKGROUND: Intra-abdominal vascular injuries are rare during posterior lumbar spinal surgery, but they can result in major morbidity or mortality when they do occur. We are aware of no prior studies that have used prone patient positioning during magnetic resonance imaging for the purpose of characterizing the retroperitoneal iliac vasculature with respect to the intervertebral disc. The purpose of this study was to define the vascular anatomy adjacent to the lower lumbar spine with use of supine and prone magnetic resonance imaging. METHODS: A prospective observational study included thirty patients without spinal abnormality who underwent supine and prone magnetic resonance imaging without abdominal compression. The spinal levels of the aortic bifurcation and confluence of the common iliac veins were identified. The proximity of the anterior iliac vessels to the anterior and posterior aspects of the anulus fibrosus in sagittal and coronal planes was measured by two observers, and interobserver reliability was calculated. RESULTS: The aortic bifurcation and confluence of the common iliac veins were most commonly at the level of the L4 vertebral body and migrated cranially with prone positioning. The common iliac vessels were closer to the anterior aspect of the intervertebral disc and to the midline at L4-L5 as compared with L5-S1, consistent with the bifurcation at the L4 vertebral body. Prone positioning resulted in greater distances between the disc and iliac vessels at L4-L5 and L5-S1 by an average of 3 mm. The position of the anterior aspect of the anulus with respect to each iliac vessel demonstrated substantial variation between subjects. The intraclass correlation coefficient for measurement of vessel position exceeded 0.9, demonstrating excellent interobserver reliability. CONCLUSIONS: This study confirmed the L4 level of the aortic bifurcation and iliac vein coalescence but also demonstrated substantial mobility of the great vessels with positioning. Supine magnetic resonance imaging will underestimate the proximity of the vessels to the intervertebral disc. Large interindividual variation in the location of vasculature was noted, emphasizing the importance of careful study of the location of the retroperitoneal vessels on a case-by-case basis. CLINICAL RELEVANCE: Anatomic relationships between vessels and intervertebral discs on supine magnetic resonance imaging may differ from relationships during surgery with the patient in a prone position

The 2001 Mars In-Situ-Propellant-Production Precursor (MIP) Flight Demonstration

The successful performance of the five individual demonstrations of MARS IN-SITU-PROPELLANT-PRODUCTION PRECURSOR (MIP) will provide both knowledge of and confidence in the reliability of this technology. At the completion of this flight demonstration, the MIP Team will be able to: a) recommend preferred hardware configurations for the intake and adsorption of carbon dioxide from the Martian atmosphere; b) understand the performance characteristics of zirconia cells to generate propellant-grade oxygen; c) understand long-term performance characteristics of advanced solar cells/arrays operated in the actual Mars environment; d) evaluate the functionality of methods to mitigate the deposition of airborne dust onto solar arrays; and e) recommend preferred hardware designs for innovative thermal management including the radiation of heat to the outside environment

Ground Delay Program Analytics with Behavioral Cloning and Inverse Reinforcement Learning

We used historical data to build two types of model that predict Ground Delay Program implementation decisions and also produce insights into how and why those decisions are made. More specifically, we built behavioral cloning and inverse reinforcement learning models that predict hourly Ground Delay Program implementation at Newark Liberty International and San Francisco International airports. Data available to the models include actual and scheduled air traffic metrics and observed and forecasted weather conditions. We found that the random forest behavioral cloning models we developed are substantially better at predicting hourly Ground Delay Program implementation for these airports than the inverse reinforcement learning models we developed. However, all of the models struggle to predict the initialization and cancellation of Ground Delay Programs. We also investigated the structure of the models in order to gain insights into Ground Delay Program implementation decision making. Notably, characteristics of both types of model suggest that GDP implementation decisions are more tactical than strategic: they are made primarily based on conditions now or conditions anticipated in only the next couple of hours

Neurologic improvement after thoracic, thoracolumbar, and lumbar spinal cord (conus medullaris) injuries

Study Design. Retrospective. Objective. With approximately 10,000 new spinal cord injury (SCI) patients in the United States each year, predicting public health outcomes is an important public health concern. Combining all regions of the spine in SCI trials may be misleading if the lumbar and sacral regions (conus) have a neurologic improvement at different rates than the thoracic or thoracolumbar spinal cord. Summary of Background Data. Over a 10-year period between January 1995 to 2005, 1746 consecutive spinal injured patients were seen, evaluated, and treated through a level 1 trauma referral center. A retrospective analysis was performed on 150 patients meeting the criteria of T4 to S5 injury, excluding gunshot wounds. One-year follow-up data were available on 95 of these patients. Methods. Contingency table analyses (chi-squared statistics) and multivariate logistic regression. Variables of interest included level of injury, initial American Spinal Injury Association (ASIA), age, race, and etiology. Results. A total of 92.9% of lumbar (conus) patients neurologically improved one ASIA level or more compared with 22.4% of thoracic or thoracolumbar spinal cord-injured patients. Only 7.7% of ASIA A patients showed neurologic improvement, compared with 95.2% of ASIA D patients; ASIA B patients demonstrated a 66.7% improvement rate, whereas ASIA C had a 84.6% improvement rate. When the two effects were considered jointly in a multivariate analysis, ASIA A and thoracic/thoracolumbar patients had only a 4.1% rate of improvement, compared with 96% for lumbar (conus) and incomplete patients (ASIA B-D) and 66.7% to 72.2% for the rest of the patients. All of these relationships were significant to P \u3c 0.001 (chi-square test). There was no link to age or gender, and race and etiology were secondary to region and severity of injury. Conclusion. Thoracic (T4-T9) SCIs have the least potential for neurologic improvement. Thoracolumbar (T10-T12) and lumbar (conus) spinal cord have a greater neurologic improvement rate, which might be related to a greater proportion of lower motor neurons. Thus, defining the exact region of injury and potential for neurologic improvement should be considered in future clinical trial design. Combining all anatomic regions of the spine in SCI trials may be misleading if different regions have neurologic improvement at different rates. Over a ten-year period, 95 complete thoracic/thoracolumbar SCI patients had only a 4.1% rate of neurologic improvement, compared with 96.0% for incomplete lumbar (conus) patients and 66.7% to 72.2% for all others

Uneven integration for perception and action cues in children’s working memory

We examined the development of visual cue integration in a desktop working-memory task using boxes with different visual action cues (opening actions) and perceptual surface cues (colours, monochromatic textures, or images of faces). Children had to recall which box held a hidden toy, based on (a) the action cue, (b) the surface cue, or (c) a conjunction of the two. Results from three experiments show a set of asymmetries in children's integration of action and surface cues. The 18–24-month-olds disregarded colour in conjunction judgements with action; 30–36-month-olds used colour but disregarded texture. Images of faces were not disregarded at either age. We suggest that 18–24-month-olds' disregard of colour, seen previously in reorientation tasks (Hermer & Spelke, 1994), may represent a general phenomenon, likened to uneven integration between the dorsal and ventral streams in early development