A Measurement of the Antiproton Flux in the Cosmic Rays

A balloon-borne instrument has been used to detect cosmic-ray antiprotons. These are identified topologically by the appearance of annihilation prongs in a thick lead-plate spark chamber. The initial recording of the data is enriched in potential antimatter events by a selective trigger. After a small subtraction for background, 14 identified antiprotons yield a flux of 1.7 plus or minus 0.00005 antiproton/(sq m ster sec MeV) between 130 and 320 MeV at the top of the atmosphere. When combined with higher energy antiproton flux measurements, this result indicates that the antiprotons have a spectrum whose shape is the same as that of the protons, but with a magnitude reduced by a factor of 1/3000

Leaf beetles are ant-nest beetles: the curious life of the juvenile stages of case-bearers (Coleoptera, Chrysomelidae, Cryptocephalinae)

Although some species of Cryptocephalinae (Coleoptera: Chrysomelidae) have been documented with ants (Hymenoptera: Formicidae) for almost 200 years, information on this association is fragmentary. This contribution synthesizes extant literature and analysizes the data for biological patterns. Myrmecophily is more common in the tribe Clytrini than in Cryptocephalini, but not documented for Fulcidacini or the closely-related Lamprosomatinae. Myrmecophilous cryptocephalines (34 species in 14 genera) primarily live among formicine and myrmecines ants as hosts. These two ant lineages are putative sister-groups, with their root-node dated to between 77–90 mya. In the New World tropics, the relatively recent radiation of ants from moist forests to more xeric ecosystems might have propelled the association of cryptocephalines and ant nests. Literature records suggest that the defensive behavioral profile or chemical profile (or both) of these ants has been exploited by cryptocephalines. Another pattern appears to be that specialized natural enemies, especially parasitoid Hymenoptera, exploit cryptocephaline beetles inside the ant nests. With the extant data at hand, based on the minimum age of a fossil larva dated to 45 mya, we can infer that the origin of cryptocephaline myrmecophily could have arisen within the Upper Cretaceous or later. It remains unknown how many times myrmecophily has appeared, or how old is the behavior. This uncertainty is compounded by incongruent hypotheses about the origins of Chrysomelidae and angiosperm-associated lineages of cryptocephalines. Living with ants offers multiple advantages that might have aided the colonization of xeric environments by some cryptocephaline species.Fil: Agrain, Federico Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Buffington, Matthew L.. National Museum of Natural History; Estados UnidosFil: Chaboo, Caroline S.. University of Kansas; Estados UnidosFil: Chamorro, Maria L.. National Museum of Natural History; Estados UnidosFil: Schöller, Matthias. Humboldt-Universität zu Berlin; Alemani

The Indianapolis Motor Speedway

This case study is intended to illustrate the issues surrounding planning and implementation of an enterprise system in a large organization with disparate business functions, with particular emphasis on application implementation, best practices, and IT investment decisions. It is recommended for either undergraduate- or graduate-level course work

Effective Use of Case Studies in the MIS Capstone Course through Semi-Formal Collaborative Teaching

This paper provides the theoretical grounding for the development of an instrument to assess the effectiveness of the case study approach in teaching the higher-level concepts associated with the MIS capstone course. The instrument was administered to students in the capstone class over three semesters. The resulting findings from the survey, combined with an understanding of each instructor’s approach to teaching case studies are then used collaboratively by the instructors as a means to identify strengths and areas for improvement. Items in the survey were developed from applicable prior research on teaching and learning and collaborative teaching. Responses to the survey items were subjected to an exploratory factor analysis, resulting in two dimensions of interest – teaching substance and teaching technique. The results of the survey indicate widespread satisfaction by students with the case study approach

Calibration of a Stack of NaI Scintillators at the Berkeley Bevalac

A stack of twelve NaI (Tl) discs, 2 cm think each, has been exposed to sea level muons, and to beams of relativistic carbon, neon, argon, and manganese at the Berkeley Bevalac. For ^(55)Mn with γ = 2.75, the position-measuring accuracy of individual discs is better than ±2 mm, individual layer responses are close to the Landau distribution, and residual error for measuring total kinetic energy of the stopping ions is less than 0.25%

Initial results from the Caltech/DRSI balloon-borne isotope experiment

The Caltech/DSRI balloonborne High Energy Isotope Spectrometer Telescope (HEIST) was flown successfully from Palestine, Texas on 14 May, 1984. The experiment was designed to measure cosmic ray isotopic abundances from neon through iron, with incident particle energies from approx. 1.5 to 2.2 GeV/nucleon depending on the element. During approximately 38 hours at float altitude, 100,000 events were recorded with Z or = 6 and incident energies approx. 1.5 GeV/nucleon. We present results from the ongoing data analysis associated with both the preflight Bevalac calibration and the flight data

A Cerenkov - ΔE/ΔX Experiment for Measuring Cosmic-Ray Isotopes from Neon Through Iron

A ballon-borne cosmic-ray experiment has been constructed to measure cosmic-ray isotope masses, It employs a pair of Cerenkov counters and a NaI scintillator stack to determine changes in ΔE in energy and Δγ in Lorentz factor for a traversing or stopping particle. Mass M = ΔE/Δγ. Mass resolution better than 0.3 a.m.u. is expected for incident elements from neon through iron, with incident Lorentz gammas ranging from 2.4 to 3.1, depending on the element. Using data obtained at the Berkeley Bevalac, the mass resolution ∂M ≈ 2 a.m.u., measured for ^(55)Mn ions with incident γ = 2.5

Initial Results from the Caltech/DSRI Balloon-Borne Isotope Experiment

The Caltech/DSRI balloonborne High Energy Isotope Spectrometer Telescope (HEIST) was flown successfully from Palestine, Texas on 14 May, 1984. The experiment was designed to measure cosmic ray isotopic abundances from neon through iron, with incident particle energies from ~1.5 to 2.2 GeV/nucleon depending on the element. During ~38 hours at float altitude, > 10^5 events were recorded with Z ≥ 6 and incident energies ≳ 1.5 GeV/nucleon. We present results from the ongoing data analysis associated with both the preflight Bevalac calibration and the flight data