Gamma ray transients

The discovery of cosmic gamma ray bursts was made with systems designed at Los Alamos Laboratory for the detection of nuclear explosions beyond the atmosphere. HELIOS-2 was the first gamma ray burst instrument launched; its initial results in 1976, seemed to deepen the mystery around gamma ray transients. Interplanetary spacecraft data were reviewed in terms of explaining the behavior and source of the transients

Design entrepreneurship as teaching methodology / Thomas Cline

As more design students plan for non-traditional jobs in the gig economy, it seems prudent to accommodate their educational needs within traditional models of design education. While most forms of design education are focused on producing designers that join traditional design firms, we should also accommodate those students who wish to work on task-based projects or open their own firms. Having found this additional content difficult to fit into the current curriculum, we have begun a student-centered design incubator and consultancy that allows our students to learn by doing—by becoming design entrepreneurs while remaining sheltered by the resources of the university. Louisiana Design Works provides educational and physical resources to students who wish to establish their own design-centered enterprises. These enterprises can take many forms; freelance opportunities, consultancies, graphic design firms, photography studios, and small-scale design and fabrication shops. It is through Louisiana Design Works that we teach our students skills beyond those typical to an undergraduate design education. They learn, in a very hands-on way, to research, design, market and manage their businesses, and manufacture and/or provide the services specific to their individual goals and aspirations. In creating this opportunity, we are able to promote, and retain, local designers and the products and services that they produce. In this way, we contribute to educational practices, economic growth, and community prosperity. While we do not yet have sufficient data to make substantial claims, we hold that this methodology is worth further exploration and would encourage others to adopt such a model of education

Kinetic description of fermion flavor mixing and CP-violating sources for baryogenesis

We derive transport equations for fermionic systems with a space-time dependent mass matrix in flavor space allowing for complex elements leading to CP violation required for electroweak baryogenesis. By constructing appropriate projectors in flavor space of the relevant tree level Kadanoff-Baym equations, we split the constraint equations into "diagonal" and "transversal" parts in flavor space, and show that they decouple. While the diagonal densities exhibit standard dispersion relations at leading order in gradients, the transverse densities exhibit a novel on-shell structure. Next, the kinetic equations are considered to second order in gradients and the CP-violating source terms are isolated. This requires a thorough discussion of a flavor independent definition of charge-parity symmetry operation. To make a link with baryogenesis in the supersymmetric extension of the Standard Model, we construct the Green functions for the leading order kinetic operator and solve the kinetic equations for two mixing fermions (charginos). We take account of flavor blind damping, and consider the cases of inefficient and moderate diffusion. The resulting densities are the CP-violating chargino currents that source baryogenesis.Comment: 33 pages, 6 figure

Axial Currents from CKM Matrix CP Violation and Electroweak Baryogenesis

The first principle derivation of kinetic transport equations suggests that a CP-violating mass term during the electroweak phase transition can induce axial vector currents. Since the important terms are of first order in gradients there is a possibility to construct new rephasing invariants that are proportional to the CP phase in the Cabibbo-Kobayashi-Maskawa matrix and to circumvent the upper bound of CP-violating contributions in the Standard Model, the Jarlskog invariant. Qualitative arguments are given that these new contributions still fail to explain electroweak baryogenesis in extensions of the Standard Model with a strong first order phase transition.Comment: RevTeX, 8 pages, 6 figure

Satellite Servicing in the Space Station Era

Repair and serv1c1ng of orbiting satellites in the Space Station era will realize significant enhancements to the capabilities available to date. The first on-orbit repair of an orbiting satellite was demonstrated in 1972 on the Skylab mission using makeshift tools, procedures, and Extravehicular Activity (EVA) techniques. Subsequently, in 1984, the repair and resultant extension of the Solar Maximum Mission (SMM) took full advantage of the spacecraft\u27s having been designed at the outset to be repaired and modified on orbit. Although this mission, among others performed by the Space Transportation System (STS) (Westar 6, Palapa 8-2, and Leasat F3), testified to the fact that much progress had been made in the on-orbit repair and servicing of satellites, it also served to highlight the areas in which considerable improvement and technology development were needed. The Space Station capabilities for on-orbit servicing will serve to provide these improvements and technology advances. By expanding on the servicing experience and capabilities provided directly by the STS, the Space Station will significantly enhance mission objectives of long-duration scientific missions, not only by repair and consumable replenishment, but also by the addition and replacement of scientfic instruments with upgraded versions. Major observatory missions such as the Hubble Space Telescope (HST), the Gamma Ray Observatory (GRO), and the Advanced X-ray Astronomical Facility (AXAF) will be among the beneficiaries of this new, enhanced capability. This paper will describe the satellite servicing capabilities planned for the Space Station

MSSM Electroweak Baryogenesis and Flavour Mixing in Transport Equations

We make use of the formalism developed in Ref. [1], and calculate the chargino mediated baryogenesis in the Minimal Supersymmetric Standard Model. The formalism makes use of a gradient expansion of the Kadanoff-Baym equations for mixing fermions. For illustrative purposes, we first discuss the semiclassical transport equations for mixing bosons in a space-time dependent Higgs background. To calculate the baryon asymmetry, we solve a standard set of diffusion equations, according to which the chargino asymmetry is transported to the top sector, where it biases sphaleron transitions. At the end we make a qualitative and quantitative comparison of our results with the existing work. We find that the production of the baryon asymmetry of the Universe by CP-violating currents in the chargino sector is strongly constrained by measurements of electric dipole moments.Comment: 30 pages, 6 figures; minor changes, published versio

Blown Away: a Case Study in Modulated Airflow through Digital Modeling and Fabrication

This paper describes an interdisciplinary project: the design and fabrication of temporary HVAC diffusers for the University of Louisiana Lafayette School of Architecture and Design to decrease and distribute air supply across the studio environment. To begin the design process, we charged the students to record data measuring the air velocity around the existing diffusers using an anemometer, creating a grid of yarn to located points in space. In addition to collecting the numerical data, the student observed the movement of the lengths of yarn in response to the airflow. Once the students could visualize the movement of the air, they hypothesized on how best to control the air. Several designs provided variations on ductwork typology, featuring perforations or shaping flanges to distribute the air. By contrast, three designs employed rudders or fins and waterfall-like shelf structures to create spouts, conceiving of the air as a fluid. With a task to spread and slow the air, these solutions were destined to be most successful. The project acts as a case study on data collection, research, and design for environmental factors. Students learned how to frame a research question, follow an organized practice of data collection and analysis, relate that data to industry-established standards, hypothesize about solutions through prototyping, test those solutions through digital analysis, and then verify hypotheses through empirical collection of data once their design was installed. This methodology allowed students to relate benchmarks established by ASHRAE’s standards for comfort to the qualitative experience of their own design. Additionally, this project serves as an example of cross-disciplinary research, and provides a model for college initiated grant development, specifically tailored to STEM

A Possible Cepheid-Like Luminosity Estimator for the Long Gamma-Ray Bursts

We present a possible Cepheid-like luminosity estimator for the long gamma-ray bursts based on the variability of their light curves. To construct the luminosity estimator, we use CGRO/BATSE data for 13 bursts, Wind/KONUS data for 5 bursts, Ulysses/GRB data for 1 burst, and NEAR/XGRS data for 1 burst. Spectroscopic redshifts, peak fluxes, and high resolution light curves are available for 11 of these bursts; partial information is available for the remaining 9 bursts. We find that the isotropic-equivalent luminosities L of these bursts positively correlate with a rigorously-constructed measure V of the variability of their light curves. We fit a model to these data that accommodates both intrinsic scatter (statistical variance) and extrinsic scatter (sample variance). If one excludes GRB 980425 from the fit on the grounds that its association with SN 1998bw at a redshift of z = 0.0085 is not secure, the luminosity estimator spans approx. 2.5 orders of magnitude in L, and the slope of the correlation between L and V is positive with a probability of 1 - 1.4 x 10^-4 (3.8 sigma). Although GRB 980425 is excluded from this fit, its L and V values are consistent with the fitted model, which suggests that GRB 980425 may well be associated with SN 1998bw, and that GRB 980425 and the cosmological bursts may share a common physical origin. If one includes GRB 980425 in the fit, the luminosity estimator spans approx. 6.3 orders of magnitude in L, and the slope of the correlation is positive with a probability of 1 - 9.3 x 10^-7 (4.9 sigma). Independently of whether or not GRB 980425 should be included in the fit, its light curve is unique in that it is much less variable than the other approx. 17 light curves in our sample for which the signal-to-noise is reasonably good.Comment: Accepted to The Astrophysical Journal, 31 pages, 13 figures, LaTe