Local gauge theory and coarse graining

Within the discrete gauge theory which is the basis of spin foam models, the problem of macroscopically faithful coarse graining is studied. Macroscopic data is identified; it contains the holonomy evaluation along a discrete set of loops and the homotopy classes of certain maps. When two configurations share this data they are related by a local deformation. The interpretation is that such configurations differ by "microscopic details". In many cases the homotopy type of the relevant maps is trivial for every connection; two important cases in which the homotopy data is composed by a set of integer numbers are: (i) a two dimensional base manifold and structure group U(1), (ii) a four dimensional base manifold and structure group SU(2). These cases are relevant for spin foam models of two dimensional gravity and four dimensional gravity respectively. This result suggests that if spin foam models for two-dimensional and four-dimensional gravity are modified to include all the relevant macroscopic degrees of freedom -the complete collection of macroscopic variables necessary to ensure faithful coarse graining-, then they could provide appropriate effective theories at a given scale.Comment: Based on talk given at Loops 11-Madri

Analysis of Nd3+:glass, solar-pumped, high-powr laser systems

The operating characteristics of Nd(3+):glass lasers energized by a solar concentrator were analyzed for the hosts YAG, silicate glass, and phosphate glass. The modeling is based on the slab zigzag laser geometry and assumes that chemical hardening methods for glass are successful in increasing glass hardness by a factor of 4. On this basis, it was found that a realistic 1-MW solar-pumped laser might be constructed from phosphate glass 4 sq m in area and 2 mm thick. If YAG were the host medium, a 1-MW solar-pumped laser need only be 0.5 sq m in area and 0.5 cm thick, which is already possible. In addition, Nd(3+) doped glass fibers were found to be excellent solar-pumped laser candidates. The small diameter of fibers eliminates thermal stress problems, and if their diameter is kept small (10 microns), they propagate a Gaussian single mode which can be expanded and transmitted long distances in space. Fiber lasers could then be used for communications in space or could be bundled and the individual beams summed or phase-matched for high-power operation

Bound-state dark matter with Majorana neutrinos

We propose a simple scenario in which dark matter (DM) emerges as a stable neutral hadronic thermal relics, its stability following from an exact $\operatorname{U}(1)_D$ symmetry. Neutrinos pick up radiatively induced Majorana masses from the exchange of colored DM constituents. There is a common origin for both dark matter and neutrino mass, with a lower bound for neutrinoless double beta decay. Direct DM searches at nuclear recoil experiments will test the proposal, which may also lead to other phenomenological signals at future hadron collider and lepton flavour violation experiments.Comment: 9 pages, 4 figures. arXiv admin note: text overlap with arXiv:1803.0852

Many-body effects in doped graphene on a piezoelectric substrate

We investigate the many-body properties of graphene on top of a piezoelectric substrate, focusing on the interaction between the graphene electrons and the piezoelectric acoustic phonons. We calculate the electron and phonon self-energies as well as the electron mobility limited by the substrate phonons. We emphasize the importance of the proper screening of the electron-phonon vertex and discuss the various limiting behaviors as a function of electron energy, temperature, and doping level. The effect on the graphene electrons of the piezoelectric acoustic phonons is compared with that of the intrinsic deformation acoustic phonons of graphene. Substrate phonons tend to dominate over intrinsic ones for low doping levels at high and low temperatures.Comment: 13 pages, 8 figure

An Analysis of Fitness, Stress and Job Performance: Concerns of Greensboro, North Carolina and Western New York Police Officers

Police Officers who have to handle stress daily, regardless of years on the force, should be in good physical condition to meet the psychological and physical stress challenges of police work. Police officers (N = 245) participated in the study. The officers consisted largely of male uniformed officers between the ages of 26-30. Data were collected using a seventy-one item police performance-fitness survey instrument and analyzed in relation to a Time on the Job (T.O.J.) variable for 1 ) 1 to 5; 2) 6 to 10; 3) 11 to 15; and 4) 15 + years on the job. The study included model fitness officers from Greensboro, N.C. and survey officers from Western New York (WNY). The questionnaire was developed to identify if physical fitness is of concern to the officers surveyed, if officers report physical fitness relates to their stress management and job performance, if model officers as compared to survey officers differ significantly in response to the survey questions and what the surveyed officers report their departments are doing for them in relation to physical fitness. The study lasted approximately two years. The level of statistical significance was set at (P\u3c .05) for chi-square values. Ninety-three percent of the officers surveyed stated they wanted to be involved in fitness programs. Yet, only 2 % of the WNY officers reported that their departments require periodic fitness test or standards after graduation from the academy. These responses were statistically significant for all T.O.J. groups with the exception of the third group. Of the officers involved in fitness programs, 67% felt it improved their job performance. This was statistically insignificant (P \u3e .05) for all comparisons. Final Communality estimates totals ranged between 3.50 and 3.96 showing that when sample questions from the survey were categorized according to stress, diet, department, personal fitness, fitness performance and health for factor analysis, overall, regardless of T.O.J ., there was little significant difference and that the model and survey groups were more alike than different in their responses to categorized questions. The study reveals that physical fitness is recognized by model and survey officers, but is not being promoted by Western New York Police Departments

2 GHz +14 dBm CMOS power amplifier for Low Power Wide Area Networks

Abstract. The design of a radiofrequency power amplifier (RF PA) for narrowband low-power wide area networks is presented in this thesis. Particularly, this RF PA is compliant with the 3GPP TS 36.101 standard for a NB1 device within the Power Class 6. To minimize silicon area consumption, this CMOS RF PA employs a single-ended single-stage topology, avoiding inter-stage matching network inductors and output baluns. This RF PA produces +14 dBm of output power with a PAE of 25% and an EVM better than 4% (−28 dB). Also, its out-of-band and spurious emissions satisfy the standard specifications with a large margin. Furthermore, it provides high ruggedness, tolerating an antenna mismatch with a VSWR of 8:1

Economic Implications of the Mexican Fruit Fly Infestation in Texas

The Texas citrus industry is threatened by the presence of Mexican fruit fly. The objective of this study was to estimate the economic losses caused by this invasive pest. Economic impact is estimated in terms of loss in revenue and increase in operating costs. Under current quarantined areas and pest management strategies, the Texas citrus industry could experience an annual economic loss of $5.79 million. The analysis was extended to evaluate the economic impact associated with different quarantined area scenarios. This article can be used to increase awareness and adapted to estimate the economic impact of emerging invasive pest outbreaks