A primer on using Monte Carlo simulations to evaluate marksmanship

Purpose – Evaluating warfighter lethality is a critical aspect of military performance. Raw metrics such as marksmanship speed and accuracy can provide some insight, yet interpreting subtle differences can be challenging. For example, is a speed difference of 300 milliseconds more important than a 10% accuracy difference on the same drill? Marksmanship evaluations must have objective methods to differentiate between critical factors while maintaining a holistic view of human performance. Design/methodology/approach – Monte Carlo simulations are one method to circumvent speed/accuracy trade-offs within marksmanship evaluations. They can accommodate both speed and accuracy implications simultaneously without needing to hold one constant for the sake of the other. Moreover, Monte Carlo simulations can incorporate variability as a key element of performance. This approach thus allows analysts to determine consistency of performance expectations when projecting future outcomes. Findings – The review divides outcomes into both theoretical overview and practical implication sections. Each aspect of the Monte Carlo simulation can be addressed separately, reviewed and then incorporated as a potential component of small arms combat modeling. This application allows for new human performance practitioners to more quickly adopt the method for different applications. Originality/value – Performance implications are often presented as inferential statistics. By using the Monte Carlo simulations, practitioners can present outcomes in terms of lethality. This method should help convey the impact of any marksmanship evaluation to senior leadership better than current inferential statistics, such as effect size measures

Banded Application of Phosgard 0-40-0 to a representative area in Guam’s Pago Watershed

Water quality and coral reef health in Guam are greatly affected by surface runoff from sedimentation. Mitigation strategies (i.e. tree planting) are difficult to implement in highly degraded settings. We propose to conduct research testing mitigation strategies focusing on ameliorative soil enrichment. We hypothesize that increasing the soils’ resiliency in Guam’s Pago Watershed by banded application of Phosgard 0-40-0 will address critical soil fertility deficiencies (i.e. phosphorus, organic matter, and pH levels). Subsequent landscape scale mitigation projects on Guam may better address reduction from the damaging energy in surface water runoff resulting in extreme soil erosion and sedimentation. These actions are important to support landscape scale restoration of native forest plants. In a representative area of 100’ x 50’, a treatment area of 40’ x 50’ with a slope of 5-7%, Phosgard 0-40-0 (0.5lb) will be applied to three treatment contour lines (20’L x 0.5’W x 0.25’H). Baseline data collection will include line transect and reference photo plots. Specialized tools will be used to take before treatment soil samples which will be analyzed to measure nutrient content, organic matter, and pH level. Data regarding vegetative response to banding of Phosgard 0-40-0 will be collected and used to determine treatment effectiveness. This method of applying Phosgard 0-40-0 may be further refined and simplified in the future, which will permit the public to assist in conservation efforts. For future studies, the effectiveness of limestone quarry dust may be tested as a low cost locally available soil amendment for landscape scale mitigation projects

Reuseable Orbital Transfer Vehicles: Why it is the Future for LEO, Cislunar Space and Beyond

The emerging Low-Earth-Orbit commercial economy brings exciting opportunities for technological innovation in space at unprecedented speed. This vibrant new commercial space age is disrupting the status quo, driving down costs, and revolutionizing general accessibility and sustained presence in LEO. Today, however, there is a reluctance in the space industry to embrace reusable spacecraft because of the perception of increased mission risk for no additional return on investment. This hesitation appears similar to the industry’s initial caution in adopting reusable launch vehicles in the early 2000s. In this work we share our vision of the future: reusable orbital service vehicles (OSVs) will transform the space economy and grow the emerging on-orbit servicing sector. A reusable OSV serves as a satellite’s ‘connecting flight’ that provides multiple on-orbit destinations, analogous to the airline industry. Development of a reliable, reusable OSV will expand the utility of a single satellite, allowing for plane changes, escape trajectories, multi-orbit missions and more. OSVs further enable payload upgrades, satellite constellation maintenance, deorbiting at the end of operational life, and orbital debris removal. These added capabilities differentiate reusable OSVs from single orbit mission alternatives and increase the on-orbit economic opportunity. Once a network of OSVs has been established in LEO, rendezvous and transfers can be scheduled efficiently to minimize on-orbit wait times between connections. This poster emphasizes current trends in the industry and presents an OSV architecture and logistics model that enables expanded access to space. Safety and reliability aspects are considered, and a satellite constellation design reference mission discussed. Future work will leverage 6 decades of hard-won lessons and insights from the commercial airline industry with its hub and spoke carrier models to improve OSV reliability and cost effectiveness. Just like reusable launch vehicles drastically reduced launch costs, and well-placed hub airports transformed the costs and safety of commercial air travel, reusable OSVs and orbital infrastructure have the potential to increase space asset safety and return on investment. These vehicles have utility in LEO and cislunar space, as well as far reaching deep space missions to Mars and beyond. Ultimately, more affordable, sustained access to space will enable the next deep space telescope, space station, or other similarly bold and impactful endeavors to be built and deployed in orbit at a fraction of the cost of a terrestrially built equivalent

Disk Detective: Discovery of New Circumstellar Disk Candidates through Citizen Science

The Disk Detective citizen science project aims to find new stars with 22 micron excess emission from circumstellar dust using data from NASA's WISE mission. Initial cuts on the AllWISE catalog provide an input catalog of 277,686 sources. Volunteers then view images of each source online in 10 different bands to identify false-positives (galaxies, background stars, interstellar matter, image artifacts, etc.). Sources that survive this online vetting are followed up with spectroscopy on the FLWO Tillinghast telescope. This approach should allow us to unleash the full potential of WISE for finding new debris disks and protoplanetary disks. We announce a first list of 37 new disk candidates discovered by the project, and we describe our vetting and follow-up process. One of these systems appears to contain the first debris disk discovered around a star with a white dwarf companion: HD 74389. We also report four newly discovered classical Be stars (HD 6612, HD 7406, HD 164137, and HD 218546) and a new detection of 22 micron excess around a previously known debris disk host star, HD 22128.Comment: 50 pages, accepted for publication in the Astrophysical Journa

Serology reveals heterogeneity of Plasmodium falciparum transmission in northeastern South Africa: implications for malaria elimination

BACKGROUND: It is widely acknowledged that modifications to existing control interventions are required if South Africa is to achieve malaria elimination. Targeting indoor residual spraying (IRS) to areas where cases have been detected is one strategy currently under investigation in northeastern South Africa. This seroprevalence baseline study, nested within a targeted IRS trial, was undertaken to provide insights into malaria transmission dynamics in South Africa and evaluate whether sero-epidemiological practices have the potential to be routinely incorporated into elimination programmes. METHODS: Filter-paper blood spots, demographic and household survey data were collected from 2710 randomly selected households in 56 study wards located in the municipalities of Ba-Phalaborwa and Bushbuckridge. Blood spots were assayed for Plasmodium falciparum apical membrane antigen-1 and merozoite surface protein-119 blood-stage antigens using an enzyme linked immunosorbent assay. Seroprevalence data were analysed using a reverse catalytic model to determine malaria seroconversion rates (SCR). Geospatial cluster analysis was used to investigate transmission heterogeneity while random effects logistic regression identified risk factors associated with malaria exposure. RESULTS: The overall SCR across the entire study site was 0.012 (95% CI 0.008-0.017) per year. Contrasting SCRs, corresponding to distinct geographical regions across the study site, ranging from <0.001 (95% CI <0.001-0.005) to 0.022 (95% CI 0.008-0.062) per annum revealed prominent transmission heterogeneity. Geospatial cluster analysis of household seroprevalence and age-adjusted antibody responses detected statistically significant (p < 0.05) spatial clusters of P. falciparum exposure. Formal secondary education was associated with lower malaria exposure in the sampled population (AOR 0.72, 95% CI 0.56-0.95, p = 0.018). CONCLUSIONS: Although overall transmission intensity and exposure to malaria was low across both study sites, malaria transmission intensity was highly heterogeneous and associated with low socio-economic status in the region. Findings suggest focal targeting of interventions has the potential to be an appropriate strategy to deploy in South Africa. Furthermore, routinely incorporating sero-epidemiological practices into elimination programmes may prove useful in monitoring malaria transmission intensity in South Africa, and other countries striving for malaria elimination

General Relativistic Geodetic Spin Precession in Binary Pulsar B1913+16: Mapping the Emission Beam in Two Dimensions

We have carefully measured the pulse profile of the binary pulsar PSR B1913+16 at 21 cm wavelength for twenty years, in order to search for variations that result from general relativistic geodetic precession of the spin axis. The profile width is found to decrease with time in its inner regions, while staying essentially constant on its outer skirts. We fit these data to a model of the beam shape and precession geometry. Four equivalent solutions are found, but evolutionary considerations and polarization data select a single preferred model. While the current data sample only a limited range of latitudes owing to the long precessional cycle, the preferred model shows a beam elongated in the latitude direction and hourglass--shaped.Comment: Accepted by AP

Finding Radio Pulsars in and Beyond the Galactic Center

Radio-wave scattering is enhanced dramatically for Galactic center sources in a region with radius >~ 15 arc min. Using scattering from Sgr A* and other sources, we show that pulse broadening for pulsars in the Galactic center is {\em at least} 6.3 \nu^{-4} seconds (\nu = radio frequency in GHz) and is most likely 50--200 times larger because the relevant scattering screen appears to be within the Galactic center region itself. Pulsars beyond---but viewed through---the Galactic center suffer even greater pulse broadening and are angularly broadened by <~ 2 {\em arc min}. Periodicity searches at radio frequencies are likely to find only long period pulsars and, then, only if optimized by using frequencies >~ 7 GHz and by testing for small numbers of harmonics in the power spectrum. The optimal frequency is $\nu ~ 7.3 GHz (\Delta_{0.1}P\sqrt{\alpha})^{-1/4}$ where \Delta_{0.1} is the distance of the scattering region from Sgr A* in units of 0.1 kpc, P is the period (seconds), and \alpha is the spectral index. A search for compact sources using aperture synthesis may be far more successful than searches for periodicities because the angular broadening is not so large as to desensitize the survey. We estimate that the number of {\em detectable} pulsars in the Galactic center may range from <= 1 to 100, with the larger values resulting from recent, vigorous starbursts. Such pulsars provide unique opportunities for probing the ionized gas, gravitational potential, and stellar population near Sgr A*.Comment: 13 pages, 4 PS figures, LaTeX and requires AASTeX macro aas2pp4, accepted by ApJ, also available as http://astrosun.tn.cornell.edu/SPIGOT/papers/pulsar/gc_psr.web