Polarization of synchrotron emission from relativistic reconfinement shocks with ordered magnetic fields

We calculate the polarization of synchrotron radiation produced at the relativistic reconfinement shocks, taking into account globally ordered magnetic field components, in particular toroidal and helical fields. In these shocks, toroidal fields produce high parallel polarization (electric vectors parallel to the projected jet axis), while chaotic fields generate moderate perpendicular polarization. Helical fields result in a non-axisymmetric distribution of the total and polarized brightness. For a diverging downstream velocity field, the Stokes parameter U does not vanish and the average polarization is neither strictly parallel nor perpendicular. A distance at which the downstream flow is changing from diverging to converging can be easily identified on polarization maps as the turning point, at which polarization vectors switch, e.g., from clockwise to counterclockwise.Comment: 10 pages, 6 figures, accepted for publication in A&

Holiday Price Rigidity and Cost of Price Adjustment

Using unique retail and wholesale price data for 4,532 products carried by a major Midwestern grocery retailer, we find evidence of significant retail price rigidity during the Thanksgiving through Christmas holiday period relative to the rest of the year. We suggest that this pattern of holiday retail price rigidity is best explained by an increased opportunity cost of changing prices at these stores during the holiday period. Evidence based on discussions with retail managers suggests that during holidays the physical, managerial, and customer costs of changing prices rise considerably. Due to higher store traffic, performing tasks such as restocking shelves, handling customers’ questions and inquiries, running cash registers, cleaning, and bagging, become more urgent during holidays and thus receive priority. As a result, the holiday-period opportunity cost of price adjustment increases dramatically for the stores. The data provide a natural experimental setting to study variation in price rigidity because the products, stores, and surrounding institutional features and arrangements, including the market structure, the contractual arrangements, and the nature of relationships, etc., do not change between holiday and non-holiday weeks.Price Rigidity, Price Flexibility, Cost of Price Adjustment, Menu Cost, Holidays, Thanksgiving Holiday, Christmas Holiday, Scanner Data, Transaction Price Data, Retail Price, Wholesale Price, Natural Experiment, Opportunity Cost of Changing Price

A survey of training aids and teaching methods employed in the signal corps ROTC program

Thesis (Ed.M.)--Boston Universit

TERRORISM, PROSCRIPTION AND THE RIGHT TO RESIST IN THE AGE OF CONFLICT

This paper focuses on the international community’s response to the increased perceived threat of terrorism since 9/11 and how the so-called “war on terror” has affected our understanding of what constitutes terrorism. It briefly details some of the major legislative changes that have been enacted and examines the impact of counter-terror strategies on certain unresolved legal issues that have historically dogged the international community’s efforts to arrive at an internationally agreed definition of terror. This includes the relationship between terrorism and the right to self-determination, the emerging right to democracy, and the existence of a license to use force as a last resort against an oppressive regime. The paper explores how the failure to resolve the relationship between these international legal principles has seriously undermined the efficacy of certain proscription regimes adopted around the world. It examines whether proscription regimes are in danger of disproportionately interfering with certain fundamental freedoms thereby reducing the scope for conflict resolution between aggrieved parties engaged in violence around the world.

Pheromone-induced polarization is dependent on the Fus3p MAPK acting through the formin Bni1p

During mating, budding yeast cells reorient growth toward the highest concentration of pheromone. Bni1p, a formin homologue, is required for this polarized growth by facilitating cortical actin cable assembly. Fus3p, a pheromone-activated MAP kinase, is required for pheromone signaling and cell fusion. We show that Fus3p phosphorylates Bni1p in vitro, and phosphorylation of Bni1p in vivo during the pheromone response is dependent on Fus3p. fus3 mutants exhibited multiple phenotypes similar to bni1 mutants, including defects in actin and cell polarization, as well as Kar9p and cytoplasmic microtubule localization. Disruption of the interaction between Fus3p and the receptor-associated Gα subunit caused similar mutant phenotypes. After pheromone treatment, Bni1p-GFP and Spa2p failed to localize to the cortex of fus3 mutants, and cell wall growth became completely unpolarized. Bni1p overexpression suppressed the actin assembly, cell polarization, and cell fusion defects. These data suggest a model wherein activated Fus3p is recruited back to the cortex, where it activates Bni1p to promote polarization and cell fusion.</jats:p

Monitoring surface charge migration in the spectral dynamics of single CdSe∕CdS nanodot/nanorod heterostructures

Journal ArticleSpherical CdSe nanocrystals capped by a CdS rod-like shell exhibit interesting spectral dynamics on the single particle level. Spectral boxcar averaging reveals a high degree of correlation between the emission energy, spectral linewidth, phonon coupling strength, and emission intensity of the single nanocrystal. The results can be described in terms of a spatially varying surface charge density in the vicinity of the exciton localized in the CdSe core, leading to a quantum confined Stark effect which modifies the transition energy and the radiative rate. Whereas internal charging of the particle results in a change in the nonradiative rate, surface charges primarily influence the radiative rate. Additionally, we observe characteristic spectral dynamics in frequency space, the magnitude of which depends slightly on temperature and strongly on excitation density. By distinguishing between continuous spectral jitter and discrete spectral jumping associated with a reversible particle ionization event, we can attribute the spectral dynamics to either a slowly varying surface charge density or a rapidly occurring polarization change due to a reversible expulsion of a charge carrier from the semiconductor nanostructure. Whereas the former exhibits universal Gaussian statistics, the latter is best characterized by a Lorentzian noise spectrum. The Gaussian spectral noise increases with spectral redshift of the emission and with increasing proximity of the surface charge to the localized exciton. The observation of a high degree of correlation between peak position and linewidth right up to room temperature suggests applications of the nanocrystals as extremely sensitive single charge detectors in both solid state devices and in biomolecular labeling, where highly local measurements of the dielectric environment are required. Nanoscale control of the physical shape of nanocrystals provides a versatile test bed for studying electronic noise, making the approach relevant to a wide range of conducting and emissive solid state systems

The greedy basis equals the theta basis

We prove the equality of two canonical bases of a rank 2 cluster algebra, the greedy basis of Lee-Li-Zelevinsky and the theta basis of Gross-Hacking-Keel-Kontsevich.Comment: 17 page

Analysis and use of VAS satellite data

A series of interrelated investigations has examined the analysis and use of VAS (VISSR Atmospheric Sounder) satellite data. A case study of VAS-derived mesoscale stability parameters suggested that they would have been a useful supplement to conventional data in the forecasting of thunderstorms on the day of interest. However, the meteorological significance of small or short lived stability features was uncertain. A second investigation examined the roles of first guess and VAS radiometric data in producing sounding retrievals. The radiance data often did not have a decisive influence on the final satellite soundings. Broad-scale patterns of the first guess, radiances, and retrievals frequently were similar, whereas small scale retrieval features, especially in the dew points, were often of uncertain origin

Analysis and use of VAS satellite data

Four interrelated investigations have examined the analysis and use of VAS satellite data. A case study of VAS-derived mesoscale stability parameters suggested that they would have been a useful supplement to conventional data in the forecasting of thunderstorms on the day of interest. A second investigation examined the roles of first guess and VAS radiometric data in producing sounding retrievals. Broad-scale patterns of the first guess, radiances, and retrievals frequently were similar, whereas small-scale retrieval features, especially in the dew points, were often of uncertain origin. Two research tasks considered 6.7 micron middle tropospheric water vapor imagery. The first utilized radiosonde data to examine causes for two areas of warm brightness temperature. Subsidence associated with a translating jet streak was important. The second task involving water vapor imagery investigated simulated imagery created from LAMPS output and a radiative transfer algorithm. Simulated image patterns were found to compare favorably with those actually observed by VAS. Furthermore, the mass/momentum fields from LAMPS were powerful tools for understanding causes for the image configurations