Measuring magnetic fields in galaxies

The magnetic (B) field in the disk of a galaxy may play an important role in the dynamics and evolution of the interstellar medium (ISM). The process by which the interstellar B-field is generated and maintained is not well understood, but the general expectation is that the generated B-field will be toroidal (parallel to the disk of the galaxy). The large-scale B-field threading the cold ISM of external galaxies can be probed via optical and near-infrared (NIR) polarimetric observations. However, scattered light can introduce false-positive B-field detections into these observations and is a source of contamination. This dissertation sets a context for observations of the Milky Way B-field by assessing the degree to which scattered light affects NIR polarimetry and reporting measurements of the B-fields in the disks of several external galaxies. The polarization properties of scattered light were investigated in order to better understand the degree to which scattered light may be a source of contamination in studies of the cold ISM B-field of external galaxies. The optical and NIR polarization of three, nearby, reflection nebulae was observed, and the wavelength dependence of the polarization percentage was measured. This wavelength dependence was found to be related to the characteristics of the scattering dust grain population with the general conclusion that the total amount of polarized, scattered light decreases with increasing wavelength. This analysis was repeated for the scattering-dominated galaxy M82 to test if similar results obtained for galaxies outside the Milky Way. Observations of this object indicate that the total amount of contamination from scattered light in this object is also less at NIR wavelengths than at optical wavelengths, and they confirm that B-field generated polarization can be detected in external galaxies. A sample of edge-on galaxies was observed for NIR polarization to measure the cold ISM B-field there. These observations indicate the likely presence of non-toroidal B-fields, localized, coherent B-field structures, and spiral disk structure detectable via NIR polarimetry. A comparison of the B-fields threading the cold and hot components of the ISM suggests that these B-fields may be dynamically distinct under certain conditions

Ambiskew Hopf algebras

Necessary and sufficient conditions are obtained for an ambiskew polynomial algebra A over a Hopf k-algebra R to possess the structure of a Hopf algebra extending that of R, in which the added variables X+ and X- are skew primitive. The coradical filtration is calculated, many examples are described, and properties determined

The Birds, the Bees, and the Butterflies: the Truth about Feminist Sex

https://digitalcommons.chapman.edu/feminist_zines/1067/thumbnail.jp

Thermal Energy Storage for Load Shifting

The following document accounts for the progress made in the prototype development of our design solution since the Critical Design Review, and our group’s response to recent world events which greatly impacted planned activities. Our design challenge is to develop a thermal energy storage system which will sequester the energy from a photovoltaic (PV) array during the day and allow for its dispersal at night in the form of near boiling water. Looking at our user’s needs, we broke our design solution into four components: water heating, storage, distribution, and controls. Research of all components was conducted to ascertain which systems should be developed and which system components could be purchased. Engineering specifications were developed to directly address customer needs and to create performance goals which our final solution can be measured against. During this phase, our group was tasked with procuring all required materials, manufacturing our prototype, and conducting verification testing. The system configuration was selected in the previous phase, and lists of components were compiled, along with manufacturing steps. We have constructed our prototype, and we have completed some preliminary testing, however there is more work to be completed by our sponsor. The selected system composition is outlined, including supporting documentation for testing procedures. Our Final Design Review outlines all final development activities which have taken place and next steps required for further iteration of our prototype

Classifying training drills based on movement demands in Australian Football

Time-motion data was used to classify a selection of training drills. Ten midfielders (age=23.8±1.8yr; height=183.9±3.8cm; mass=83.2±5.0 kg) from an Australian Football League team participated in 17 training drills and four quarters of an official competitive match. Heart rate and time-motion data were collected using Global Positioning and Heart Rate Systems. Cluster analysis of mean distance travelled in the seven velocity zones identified three clusters: 1) game-specific conditioning; 2) skill refining/moderate intensity dominant; and 3) skill refining/low intensity dominant. Differences between the three clusters in distance travelled at the speed zones were confirmed using one-way ANOVA. Differences between clusters were also assessed for number of efforts in velocity zones and percentage time in heart rate zones. When compared to drills with a focus on skill refining or performed on a reduced playing area, drills utilising the entire playing field better replicated the movement characteristics of competitive game play

Wave turbulence and Bose-Einstein condensates

Asymptotic behavior of a class of nonlinear Schr\"odinger equations are studied. Particular cases of 1D weakly focusing and Bose-Einstein condensates are considered. A statistical approach is presented to describe the stationary probability density of a discretized finite system. Using a maximum entropy argument, the theory predicts that the statistical equilibrium is described by energy equivalued fluctuation modes around the coherent structure minimizing the Hamiltonian of the system. Good quantitative agreement is found with numerical simulations. In particular, the particle number spectral density follows an effective $1/k^2$ law for the asymptotic large time averaged solutions. Transient dynamics from a given initial condition to the statistically steady regime shows rapid oscillation of the condensate

The unusual pulsation spectrum of the cool ZZ Ceti star HS 0507+0434B

We present the analysis of one week of single-site high-speed CCD photometric observations of the cool ZZ Ceti star HS 0507+0434B. Ten independent frequencies are detected in the star's light variations: one singlet and three nearly-equally spaced triplets. We argue that these triplets are due to rotationally split modes of spherical degree l=1. This is the first detection of consistent multiplet structure in the amplitude spectrum of a cool ZZ Ceti star and it allows us to determine the star's rotation period: 1.70 +/- 0.11 d. We report exactly equal frequency, not period, spacings between the detected mode groups. In addition, certain pairs of modes from the four principal groups have frequency ratios which are very close to 3:4 or 4:5; while these ratios are nearly exact (within one part in 10^4), they still lie outside the computed error bars. We speculate that these relationships between different frequencies could be caused by resonances. One of the three triplets may not be constant in amplitude and/or frequency. We compare our frequency solution for the combination frequencies (of which we detected 38) to Wu's (1998, 2001) model thereof. We obtain consistent results when trying to infer the star's convective thermal time and the inclination angle of its rotational axis. Theoretical combination-frequency amplitude spectra also resemble those of the observations well, and direct theoretical predictions of the observed second-order light-curve distortions were also reasonably successful assuming the three triplets are due to l=1 modes. Attempts to reproduce the observed combination frequencies adopting all possible l=2 identifications for the triplets did not provide similarly consistent results, supporting their identification with l=1.Comment: Accepted for publication in MNRAS; 12 pages, 8 figure

A Gravitational Redshift Determination of the Mean Mass of White Dwarfs. DA Stars

We measure apparent velocities (v_app) of the Halpha and Hbeta Balmer line cores for 449 non-binary thin disk normal DA white dwarfs (WDs) using optical spectra taken for the ESO SN Ia Progenitor surveY (SPY; Napiwotzki et al. 2001). Assuming these WDs are nearby and co-moving, we correct our velocities to the Local Standard of Rest so that the remaining stellar motions are random. By averaging over the sample, we are left with the mean gravitational redshift, : we find = = 32.57 +/- 1.17 km/s. Using the mass-radius relation from evolutionary models, this translates to a mean mass of 0.647 +0.013 -0.014 Msun. We interpret this as the mean mass for all DAs. Our results are in agreement with previous gravitational redshift studies but are significantly higher than all previous spectroscopic determinations except the recent findings of Tremblay & Bergeron (2009). Since the gravitational redshift method is independent of surface gravity from atmosphere models, we investigate the mean mass of DAs with spectroscopic Teff both above and below 12000 K; fits to line profiles give a rapid increase in the mean mass with decreasing Teff. Our results are consistent with no significant change in mean mass: ^hot = 0.640 +/- 0.014 Msun and ^cool = 0.686 +0.035 -0.039 Msun.Comment: Accepted for publication in ApJ, 14 pages, 12 figure

Weakly group-theoretical and solvable fusion categories

We introduce two new classes of fusion categories which are obtained by a certain procedure from finite groups - weakly group-theoretical categories and solvable categories. These are fusion categories that are Morita equivalent to iterated extensions (in the world of fusion categories) of arbitrary, respectively solvable finite groups. Weakly group-theoretical categories have integer dimension, and all known fusion categories of integer dimension are weakly group theoretical. Our main results are that a weakly group-theoretical category C has the strong Frobenius property (i.e., the dimension of any simple object in an indecomposable C-module category divides the dimension of C), and that any fusion category whose dimension has at most two prime divisors is solvable (a categorical analog of Burnside's theorem for finite groups). This has powerful applications to classification of fusion categories and semsisimple Hopf algebras of a given dimension. In particular, we show that any fusion category of integer dimension <84 is weakly group-theoretical (i.e. comes from finite group theory), and give a full classification of semisimple Hopf algebras of dimensions pqr and pq^2, where p,q,r are distinct primes.Comment: 28 pages, latex; added many references and details in proof

Coherent states and geodesics: cut locus and conjugate locus

The intimate relationship between coherent states and geodesics is pointed out. For homogenous manifolds on which the exponential from the Lie algebra to the Lie group equals the geodesic exponential, and in particular for symmetric spaces, it is proved that the cut locus of the point $0$ is equal to the set of coherent vectors orthogonal to $\vert 0>$. A simple method to calculate the conjugate locus in Hermitian symmetric spaces with significance in the coherent state approach is presented. The results are illustrated on the complex Grassmann manifold.Comment: 19 pages, enlarged version, 14 pages, Latex + some macros from Revtex + some AMS font