A Project Based Approach to Statistics and Data Science

In an increasingly data-driven world, facility with statistics is more important than ever for our students. At institutions without a statistician, it often falls to the mathematics faculty to teach statistics courses. This paper presents a model that a mathematician asked to teach statistics can follow. This model entails connecting with faculty from numerous departments on campus to develop a list of topics, building a repository of real-world datasets from these faculty, and creating projects where students interface with these datasets to write lab reports aimed at consumers of statistics in other disciplines. The end result is students who are well prepared for interdisciplinary research, who are accustomed to coping with the idiosyncrasies of real data, and who have sharpened their technical writing and speaking skills

Ab Initio Liquid Hydrogen Muon Cooling Simulations with ELMS in ICOOL

This paper presents new theoretical results on the passage of muons through liquid hydrogen which have been confirmed in a recent experiment. These are used to demonstrate that muon bunches may be compressed by ionisation cooling more effectively than suggested by previous calculations. Muon cooling depends on the differential cross section for energy loss and scattering of muons. We have calculated this cross section for liquid H2 from first principles and atomic data, avoiding traditional assumptions. Thence, 2-D probability maps of energy loss and scattering in mm-scale thicknesses are derived by folding, and stored in a database. Large first-order correlations between energy loss and scattering are found for H2, which are absent in other simulations. This code is named ELMS, Energy Loss & Multiple Scattering. Single particle trajectories may then be tracked by Monte Carlo sampling from this database on a scale of 1 mm or less. This processor has been inserted into the cooling code ICOOL. Significant improvements in 6-D muon cooling are predicted compared with previous predictions based on GEANT. This is examined in various geometries. The large correlation effect is found to have only a small effect on cooling. The experimental scattering observed for liquid H2 in the MUSCAT experiment has recently been reported to be in good agreement with the ELMS prediction, but in poor agreement with GEANT simulation.Comment: 6 pages, 3 figure

Quantifying the Effects of Hyperthermal Atomic Oxygen and Thermal Fatigue Environments on Carbon Nanotube Sheets for Space-Based Applications

The effects of atomic oxygen and thermal fatigue on two different types of carbon nanotube sheets were studied. One set was treated with nitric acid, while the other set was left untreated. Monotonic tensile tests were performed before and after exposure to determine the effects of either exposure type on the sheets’ mechanical properties. Electrical conductivity and electromagnetic interference measurements were recorded to determine the effects of AO-exposure and thermal cycling on the sheets’ electrical properties. Neither exposure type affected the sheets’ specific strengths. Both exposure types increased the sheets’ specific stiffnesses and decreased the sheets’ strains at failure. The electrical conductivity of both sheets decreased due to the different exposure types, while the EMI shielding effectiveness was unaffected. Scanning electron microscopy was used to observe any changes in the sheets’ surface morphologies, while energy-dispersive X-ray spectroscopy was used to determine the effects of AO on the sheets’ chemical makeup

Urban transportation: Perspectives on mobility and choice

A study of urban transportation systems are presented characterized by intensive scrutiny of many ideas, philosophies, and academic perspectives. This report is intended to communicate some dimensions of the urban transportation problem to the general public

Electrical signature in polar night cloud base variations

Layer clouds are globally extensive. Their lower edges are charged negatively by the fair weather atmospheric electricity current flowing vertically through them. Using polar winter surface meteorological data from Sodankyla ̈ (Finland) and Halley (Antarctica), we find that when meteorological diurnal variations are weak, an appreciable diurnal cycle, on average, persists in the cloud base heights, detected using a laser ceilometer. The diurnal cloud base heights from both sites correlate more closely with the Carnegie curve of global atmospheric electricity than with local meteorological measurements. The cloud base sensitivities are indistinguishable between the northern and southern hemispheres, averaging a (4.0 ± 0.5) m rise for a 1% change in the fair weather electric current density. This suggests that the global fair weather current, which is affected by space weather, cosmic rays and the El Nin ̃o Southern Oscillation, is linked with layer cloud properties

GRB 050408: An Atypical Gamma-Ray Burst as a Probe of an Atypical Galactic Environment

The bright GRB 050408 was localized by HETE-II near local midnight, enabling an impressive ground-based followup effort as well as space-based followup from Swift. The Swift data from the X-Ray Telescope (XRT) and our own optical photometry and spectrum of the afterglow provide the cornerstone for our analysis. Under the traditional assumption that the visible waveband was above the peak synchrotron frequency and below the cooling frequency, the optical photometry from 0.03 to 5.03 days show an afterglow decay corresponding to an electron energy index of p_lc = 2.05 +/- 0.04, without a jet break as suggested by others. A break is seen in the X-ray data at early times (at ~12600 sec after the GRB). The spectral slope of the optical spectrum is consistent with p_lc assuming a host-galaxy extinction of A_V = 1.18 mag. The optical-NIR broadband spectrum is also consistent with p = 2.05, but prefers A_V = 0.57 mag. The X-ray afterglow shows a break at 1.26 x 10^4 sec, which may be the result of a refreshed shock. This burst stands out in that the optical and X-ray data suggest a large H I column density of N_HI ~ 10^22 cm^-2; it is very likely a damped Lyman alpha system and so the faintness of the host galaxy (M_V > -18 mag) is noteworthy. Moreover, we detect extraordinarily strong Ti II absorption lines with a column density through the GRB host that exceeds the largest values observed for the Milky Way by an order of magnitude. Furthermore, the Ti II equivalent width is in the top 1% of Mg II absorption-selected QSOs. This suggests that the large-scale environment of GRB 050408 has significantly lower Ti depletion than the Milky Way and a large velocity width (delta v > 200 km/s).Comment: ApJ submitte

Computational studies of light acceptance and propagation in straight and curved multimodal active fibres

A Monte Carlo simulation has been performed to track light rays in cylindrical multimode fibres by ray optics. The trapping efficiencies for skew and meridional rays in active fibres and distributions of characteristic quantities for all trapped light rays have been calculated. The simulation provides new results for curved fibres, where the analytical expressions are too complex to be solved. The light losses due to sharp bending of fibres are presented as a function of the ratio of curvature to fibre radius and bending angle. It is shown that a radius of curvature to fibre radius ratio of greater than 65 results in a light loss of less than 10% with the loss occurring in a transition region at bending angles of pi/8 rad.Comment: 21 pages, 13 figure

Geographic variation in host selection in the spider wasps \u3ci\u3eEntypus unifasciatus\u3c/i\u3e (Say) and \u3ci\u3eTachypompilus ferrugineus\u3c/i\u3e (Say) (Hymenoptera: Pompilidae), II

This paper is the sequel to a 20 year-long (2002–2021) study of geographic variation in host selec­tion in the common American spider wasps (Hymenoptera: Pompilidae) Entypus unifasciatus (Say) (Pepsini) and Tachypompilus ferrugineus (Say) (Pompilini) (rusty spider wasp). Geography and host spider family are strongly linked in both species when 3387 host spider locality records from the years 1918–2021 are mapped. Entypus unifasciatus lycosid host records are plentiful from 43–44° N in the United States and southern Ontario to northern Mexico. Tachypompilus ferrugineus lycosid host records are abundant from southern Ontario and New England southward to Mexico east of the Rocky Mountains. The vast majority (~80%) of E. unifasciatus and T. ferrugineus pisaurid host records are from the southeastern United States. Trechaleid host records for E. unifasciatus and T. ferrugineus are predominant in southern Mexico and Central America, while ctenid host records for these spider wasps are prevalent in Central America and, especially, South America. All E. unifasciatus sparassid host records are from extreme southwestern United States and north­ern Mexico, whereas T. ferrugineus sparassid host records are scattered from Texas, Florida and Hispaniola/Puerto Rico southward to Panama and Brazil. Based on this study Lycosidae is the predominant host spider family in the Americas for E. unifasciatus (83.1%) and T. ferrugineus (64.0%) followed by Pisauridae (4.9%, 24.8%), Trechaleidae (4.2%, 6.0%), Ctenidae (4.3%, 2.7%), and Sparassidae (3.1%, 1.6%). Lycosidae and Pisauridae are overrepresented in this study as most host records (88.1%) are from the United States and On­tario, Canada where such species are abundant. Trechaleidae and Ctenidae are grossly underrepresented as host records from Mexico, Central America and South America are scarce (11.9%). Zoropsidae/Miturgidae 2 · March 31, 2022 Kurczewski et al. and Zoropsidae/Agelenidae/Selenopidae are atypical host spider families for E. unifasciatus (0.2%, 0.2%) and T. ferrugineus (0.7%, 0.2%, \u3c0.1%), respectively. Rabidosa rabida (Walckenaer) (Lycosidae) (rabid wolf spi­der) is the predominant host spider species for both E. unifasciatus (47.7%) and T. ferrugineus (48.0%) based mainly on United States host records