The development and appraisal of a linear program for the teaching of complex numbers

After a brief review of the development of Programmed Learning the work reviews some techniques for producing linear programmes. The development of the linear programme for teaching the manipulation of complex numbers, and its preliminary trial in 1965 are described. The examination of the errors and subsequent modifications to the programmes are also shown. In 1966 the programme was administered to 33 mature students (Mean age 38) in a College of Education, who were compared with another group of 12 in the same college. This latter group had been taught the same material in a conventional way. No significant differences were found in post test scores or times needed to complete the work by either method. Some other correlations are investigated. The programme teaches successfully (Mean Gain + 72%), and methods of improving its performance for poorer students are discussed. A loop branching method is also suggested as an alternative way of helping less able students

Monte Carlo Simulation of the Rapid Crystallization of Bismuth-Doped Silicon

In this Letter we report Ising model simulations of the growth of alloys which predict quite different behavior near and far from equilibrium. Our simulations reproduce the phenomenon which has been termed 'solute trapping,' where concentrations of solute, which are far in excess of the equilibrium concentrations, are observed in the crystal after rapid crystallization. This phenomenon plays an important role in many processes which involve first order phase changes which take place under conditions far from equilibrium. The underlying physical basis for it has not been understood, but these Monte Carlo simulations provide a powerful means for investigating it

Delirium, frailty and mortality:interactions in a prospective study of hospitalized older people

AbstractBackgroundIt is unknown if the association between delirium and mortality is consistent for individuals across the whole range of health states. A bimodal relationship has been proposed, where delirium is particularly adverse for those with underlying frailty, but may have a smaller effect (perhaps even protective) if it is an early indicator of acute illness in fitter people. We investigated the impact of delirium on mortality in a cohort simultaneously evaluated for frailty.MethodsWe undertook an exploratory analysis of a cohort of consecutive acute medical admissions aged ≥70. Delirium on admission was ascertained by psychiatrists. A Frailty Index (FI) was derived according to a standard approach. Deaths were notified from linked national mortality statistics. Cox regression was used to estimate associations between delirium, frailty and their interactions on mortality.ResultsThe sample consisted of 710 individuals. Both delirium and frailty were independently associated with increased mortality rates (delirium: HR 2.4, 95%CI 1.8-3.3, p&lt;0.01; frailty (per SD): HR 3.5, 95%CI 1.2-9.9, p=0.02). Estimating the effect of delirium in tertiles of FI, mortality was greatest in the lowest tertile: tertile 1 HR 3.4 (95%CI 2.1-5.6); tertile 2 HR 2.7 (95%CI 1.5-4.6); tertile 3 HR 1.9 (95% CI 1.2-3.0).ConclusionWhile delirium and frailty contribute to mortality, the overall impact of delirium on admission appears to be greater at lower levels of frailty. In contrast to the hypothesis that there is a bimodal distribution for mortality, delirium appears to be particularly adverse when precipitated in fitter individuals.</jats:sec

Initial Investigation of Reaction Control System Design on Spacecraft Handling Qualities for Earth Orbit Docking

A program of research, development, test, and evaluation is planned for the development of Spacecraft Handling Qualities guidelines. In this first experiment, the effects of Reaction Control System design characteristics and rotational control laws were evaluated during simulated proximity operations and docking. Also, the influence of piloting demands resulting from varying closure rates was assessed. The pilot-in-the-loop simulation results showed that significantly different spacecraft handling qualities result from the design of the Reaction Control System. In particular, cross-coupling between translational and rotational motions significantly affected handling qualities as reflected by Cooper-Harper pilot ratings and pilot workload, as reflected by Task-Load Index ratings. This influence is masked but only slightly by the rotational control system mode. While rotational control augmentation using Rate Command Attitude Hold can reduce the workload (principally, physical workload) created by cross-coupling, the handling qualities are not significantly improved. The attitude and rate deadbands of the RCAH introduced significant mental workload and control compensation to evaluate when deadband firings would occur, assess their impact on docking performance, and apply control inputs to mitigate that impact

Extremes in body mass index affect overall survival in women with cervical cancer

OBJECTIVE: To examine the effect of BMI on pathologic findings, cancer recurrence and survival in cervical cancer patients. METHODS: A retrospective cohort study of cervical cancer patients treated from July 2000 to March 2013 was performed. BMI was calculated, and patients were classified by BMI. The primary outcome was overall survival (OS). Secondary outcomes included stage, histopathology, disease-specific survival (DSS) and recurrence free survival (RFS). Kaplan-Meier survival curves were generated and compared using Cox proportional hazard ratios. RESULTS: Of 632 eligible patients, 24 (4%) were underweight, 191 (30%) were normal weight, 417 (66%) were overweight/obese. There was no difference in age (p=0.91), stage at presentation (p=0.91), grade (p=0.46), or histology (p=0.76) between weight categories. There were fewer White patients in the underweight (54%) and overweight/obese (58%) groups compared to the normal weight (71%) group (p=0.04). After controlling for prognostic factors, underweight and overweight/obese patients had worse median RFS than normal weight patients (7.6 v 25.0months, p=0.01 and 20.3 v 25.0months, p=0.03). Underweight patients also had worse OS (10.4 v 28.4months, p=0.031) and DSS (13.8 v 28.4months, p=0.04) compared to normal weight patients. Overweight/obese patients had worse OS than normal weight patients (22.2 v 28.4months, p=0.03) and a trend toward worse DSS (21.9 v 28.4months, p=0.09). CONCLUSION: Both extremes of weight (underweight and overweight/obesity) were associated with worse survival in patients with cervical cancer. Optimizing weight in cervical cancer patients may improve outcomes in these patients

Human B cell lineages associated with germinal centers following influenza vaccination are measurably evolving

The poor efficacy of seasonal influenza virus vaccines is often attributed to pre-existing immunity interfering with the persistence and maturation of vaccine-induced B cell responses. We previously showed that a subset of vaccine-induced B cell lineages are recruited into germinal centers (GCs) following vaccination, suggesting that affinity maturation of these lineages against vaccine antigens can occur. However, it remains to be determined whether seasonal influenza vaccination stimulates additional evolution of vaccine-specific lineages, and previous work has found no significant increase in somatic hypermutation among influenza-binding lineages sampled from the blood following seasonal vaccination in humans. Here, we investigate this issue using a phylogenetic test of measurable immunoglobulin sequence evolution. We first validate this test through simulations and survey measurable evolution across multiple conditions. We find significant heterogeneity in measurable B cell evolution across conditions, with enrichment in primary response conditions such as HIV infection and early childhood development. We then show that measurable evolution following influenza vaccination is highly compartmentalized: while lineages in the blood are rarely measurably evolving following influenza vaccination, lineages containing GC B cells are frequently measurably evolving. Many of these lineages appear to derive from memory B cells. We conclude from these findings that seasonal influenza virus vaccination can stimulate additional evolution of responding B cell lineages, and imply that the poor efficacy of seasonal influenza vaccination is not due to a complete inhibition of vaccine-specific B cell evolution

Repulsive Casimir forces

We discuss repulsive Casimir forces between dielectric materials with non trivial magnetic susceptibility. It is shown that considerations based on naive pair-wise summation of Van der Waals and Casimir Polder forces may not only give an incorrect estimate of the magnitude of the total Casimir force, but even the wrong sign of the force when materials with high dielectric and magnetic response are involved. Indeed repulsive Casimir forces may be found in a large range of parameters, and we suggest that the effect may be realized in known materials. The phenomenon of repulsive Casimir forces may be of importance both for experimental study and for nanomachinery applications

Investigation of Control System and Display Variations on Spacecraft Handling Qualities for Docking with Stationary and Rotating Targets

This paper documents the investigation into the manual docking of a preliminary version of the Crew Exploration Vehicle with stationary and rotating targets in Low Earth Orbit. The investigation was conducted at NASA Langley Research Center in the summer of 2008 in a repurposed fixed-base transport aircraft cockpit and involved nine evaluation astronauts and research pilots. The investigation quantified the benefits of a feed-forward reaction control system thruster mixing scheme to reduce translation-into-rotation coupling, despite unmodeled variations in individual thruster force levels and off-axis center of mass locations up to 12 inches. A reduced rate dead-band in the phase-plane attitude controller also showed some promise. Candidate predictive symbology overlaid on a docking ring centerline camera image did not improve handling qualities, but an innovative attitude status indicator symbol was beneficial. The investigation also showed high workload and handling quality problems when manual dockings were performed with a rotating target. These concerns indicate achieving satisfactory handling quality ratings with a vehicle configuration similar to the nominal Crew Exploration Vehicle may require additional automation

Resolution of Failed Financial Institutions: Orderly Liquidation Authority and a New Chapter 14

Studies by the Resolution Project at Stanford University\u27s Hoover Institution Working Group on Economic Polic