Mission design for a ballistic slow flyby Comet Encke 1980

Preliminary mission analyses for a proposed 1980 slow flyby (7-9 km/s) of comet Encke are presented. Among the topics covered are science objectives, Encke's physical activity and ephemeris accuracy, trajectory and launch-window analysis, terminal guidance, and spacecraft concepts. The nominal mission plan calls for a near-perihelion intercept with two spacecraft launched on a single launch vehicle. Both spacecraft will arrive at the same time, one passing within 500 km from Encke's nucleus on its sunward side, the other cutting through the tail region. By applying a small propulsive correction about three weeks after the encounter, it is possible to retarget both spacecraft for a second Encke intercept in 1984. The potential science return from the ballistic slow flyby is compared with other proposed mission modes for the 1980 Encke flyby mission, including the widely advocated slow flyby using solar-electric propulsion. It is shown that the ballistic slow flyby is superior in every respect

Techniques for improving reliability of computers

Modular design techniques improve methods of error detection, diagnosis, and recovery. Theoretical computer (MARCS (Modular Architecture for Reliable Computer Systems)) study deals with postulated and modeled technology indigenous to 1975-1980. Study developments are discussed

Sports medicine in Hawaii: care of the high school athlete in Oahu's public schools.

A recent study by the National Athletic Trainers Association indicated that injuries occur more often during practice than during games in high school athletics. Results of the 3-year study indicated that 60% of basketball injuries occurred in boys and young men during practice and 59% occurred in women. About 2/3 of the estimated 120,000 injuries suffered by prep wrestlers each year happen during practice. The study found that an average of 331,865 high school football players (1/3 of the million who play football each year) were sidelined by an injury at least once. With these statistics in mind, our study looks at the approach to the management of injury in the public schools that make up the Oahu Inter-scholastic Association (OIA) in the state of Hawaii. The estimated number of student athletes that participate in organized athletics in the OIA is 7,960 and the number of coaches is 1,189

Buoyancy waves in Pluto's high atmosphere: Implications for stellar occultations

We apply scintillation theory to stellar signal fluctuations in the high-resolution, high signal/noise, dual-wavelength data from the MMT observation of the 2007 March 18 occultation of P445.3 by Pluto. A well-defined high wavenumber cutoff in the fluctuations is consistent with viscous-thermal dissipation of buoyancy waves (internal gravity waves) in Pluto's high atmosphere, and provides strong evidence that the underlying density fluctuations are governed by the gravity-wave dispersion relation.Comment: Accepted 18 June 2009 for publication in Icaru

Close Companions to T Tauri Stars: Abundant and Perturbing

The results of a speckle imaging survey of T Tauri stars suggest that most, if not all, young low mass stars have companions. Furthermore, this survey reveals a distinction between the classical T Tauri stars (CTTS) and the weak-lined T Tauri stars (WTTS) based on the binary star frequency as a function of separation: the WTTS binary star distribution is enhanced at the closer separations. This suggests that close companions interact with the circumstellar disk material to effectively shorten the accretion time scale in multiple star systems. Recent follow up work has revealed orbital motion in the closest pairs (≤0."3), providing (1) evidence that these systems are indeed gravitationally bound and not the result of chance superpositions and (2) the basis for mass estimates that are necessary to distinguish between the various binary star formation mechanisms that have been proposed to date

#MeToo in EM: A Multicenter Survey of Academic Emergency Medicine Faculty on Their Experiences with Gender Discrimination and Sexual Harassment

Introduction: Gender-based discrimination and sexual harassment of female physicians are well documented. The #MeToo movement has brought renewed attention to these problems. This study examined academic emergency physicians’ experiences with workplace gender discrimination and sexual harassment.Methods: We conducted a cross-sectional survey of a convenience sample of emergency medicine (EM) faculty across six programs. Survey items included the following: the Overt Gender Discrimination at Work (OGDW) Scale; the frequency and source of experienced and observed discrimination; and whether subjects had encountered unwanted sexual behaviors by a work superior or colleague in their careers. For the latter question, we asked subjects to characterize the behaviors and whether those experiences had a negative effect on their self-confidence and career advancement. We made group comparisons using t-tests or chi-square analyses, and evaluated relationships between gender and physicians’ experiences using correlation analyses.Results: A total of 141 out of 352 (40.1%) subjects completed at least a portion of the survey. Women reported higher mean OGDW scores than men (15.4 vs 10.2; 95% confidence interval [CI], 3.6–6.8). Female faculty were also more likely to report having experienced gender-based discriminatory treatment than male faculty (62.7% vs 12.5%; 95% CI, 35.1%-65.4%), although male and female faculty were equally likely to report having observed gender-based discriminatory treatment of another physician (64.7% vs 56.3%; 95% CI, 8.6%-25.5%). The three most frequent sources of experienced or observed gender-based discriminatory treatment were patients, consulting or admitting physicians, and nursing staff. The majority of women reported having encountered unwanted sexual behaviors in their careers, with a significantly greater proportion of women reporting them compared to men (52.9% vs 26.2%, 95% CI, 9.9%-43.4%). The majority of unwanted behaviors were sexist remarks and sexual advances. Of those respondents who encountered these unwanted behaviors, 22.9% and 12.5% reported at least somewhat negative effects on their self-confidence and career advancement.Conclusion: Female EM faculty perceived more gender-based discrimination in their workplaces than their male counterparts. The majority of female and approximately a quarter of male EM faculty encountered unwanted sexual behaviors in their careers.

Assessing Human Error Against a Benchmark of Perfection

An increasing number of domains are providing us with detailed trace data on human decisions in settings where we can evaluate the quality of these decisions via an algorithm. Motivated by this development, an emerging line of work has begun to consider whether we can characterize and predict the kinds of decisions where people are likely to make errors. To investigate what a general framework for human error prediction might look like, we focus on a model system with a rich history in the behavioral sciences: the decisions made by chess players as they select moves in a game. We carry out our analysis at a large scale, employing datasets with several million recorded games, and using chess tablebases to acquire a form of ground truth for a subset of chess positions that have been completely solved by computers but remain challenging even for the best players in the world. We organize our analysis around three categories of features that we argue are present in most settings where the analysis of human error is applicable: the skill of the decision-maker, the time available to make the decision, and the inherent difficulty of the decision. We identify rich structure in all three of these categories of features, and find strong evidence that in our domain, features describing the inherent difficulty of an instance are significantly more powerful than features based on skill or time.Comment: KDD 2016; 10 page

The USNO/NRL Green Bank interferometer program

Application of the connected-element radio interferometer of the National Radio Astronomy Observation in Green Bank, West Virginia to the determination of improved source coordinates, astronomical constants, and variations in Earth rotation parameters is discussed. It is concluded that because of the brevity and discontinuity of the data so far no reliable conclusions regarding the accuracy of the data can be drawn