Phantom distribution functions for some stationary sequences

The notion of a phantom distribution function (phdf) was introduced by O'Brien (1987). We show that the existence of a phdf is a quite common phenomenon for stationary weakly dependent sequences. It is proved that any $\alpha$-mixing stationary sequence with continuous marginals admits a continuous phdf. Sufficient conditions are given for stationary sequences exhibiting weak dependence, what allows the use of attractive models beyond mixing. The case of discontinuous marginals is also discussed for $\alpha$-mixing. Special attention is paid to examples of processes which admit a continuous phantom distribution function while their extremal index is zero. We show that Asmussen (1998) and Roberts et al. (2006) provide natural examples of such processes. We also construct a non-ergodic stationary process of this type

Exact solution of time-dependent Lindblad equations with closed algebras

Time-dependent Lindblad master equations have important applications in areas ranging from quantum thermodynamics to dissipative quantum computing. In this paper we outline a general method for writing down exact solutions of time-dependent Lindblad equations whose superoperators form closed algebras. We focus on the particular case of a single qubit and study the exact solution generated by both coherent and incoherent mechanisms. We also show that if the time-dependence is periodic, the problem may be recast in terms of Floquet theory. As an application, we give an exact solution for a two-levels quantum heat engine operating in a finite-time.Comment: 15 pages, 12 figure

Evaluation of a cool-season grass-white clover mixture for low-nitrogen input lawns

Turfgrass lawns require supplemental nitrogen (N) to maintain green color and seasonal shoot density. Improper lawn fertilization with excess N or phosphorus has the potential to contaminate both surface and groundwater. Thus, to reduce the reliance on supplemental N fertilization, alternative strategies or novel turf systems like grass-legume mixtures need explored. White clover ( Trifolium repens L.) is a stoloniferous legume that biologically fixes N from the atmosphere and adds N into the soil via mineralization. The objective of this field study was to evaluate the persistence and feasibility of a cool-season grass-clover lawn mixture. A lawn grass mixture with and without a novel white clover ‘Microclover’ (MC) was grown at two annual N rates (0 and 98 kg N ha-1 yr-1) for two growing seasons. Dry matter yield (DMY), yield component analysis (YCA), visual appearance, canopy greenness, clover populations, and flower production were measured. Total DMY ranged from 3815 to 15583 kg ha-1 and turf that received supplemental N produced the most DMY, 15583 and 13136 kg ha-1, respectively, for turf with and without MC. By contrast, unfertilized turf with and without MC produced 8754 and 3815 kg ha-1, respectively. The YCA in year two showed that MC contributed approximately 15% to DMY in unfertilized turf, and 3% in turf receiving supplemental N. All treatments except the unfertilized turf without MC demonstrated acceptable visual quality and where supplemental N was applied, the highest visual quality was observed. In year two, the unfertilized grass-only turf lacked vigor and was affected by two leaf blighting diseases, red thread and dollar spot, resulting in localized patches of brown, dead turf which negatively impacted visual appearance. Canopy greenness was highest in turf with MC receiving supplemental N, and lowest in unfertilized turf without MC, while unfertilized turf with MC and turf without MC receiving supplemental N were identical. Clover populations decreased over the two years regardless of supplemental N. Clover in the turf receiving supplemental N decreased substantially (17 to 1%), while slightly less in the unfertilized turf (14 to 5%), which also affected subsequent flower numbers measured in year two. In a second study, the effect of annual N-rate (0, 98, 146, 195 kg N ha-1 yr-1) on MC population changes was assessed using a poultry manure fertilizer. Although the MC populations again decreased over time, roughly 25 to 11 % across all treatments, there was surprisingly no difference due to any N-rate. This observation, demonstrates that in the future, various N-sources deserve further exploration for their compatibility with grass-legume systems. Overall, these results highlight the influence of traditional N fertilization practices on DMY, visual quality, canopy greenness, and MC persistence in a cool-season lawn grass mixture with and without MC. Further, this study demonstrated that a grass-MC lawn can persist and provide reasonable visual lawn quality and is a potentially feasible option for lawns in the cool-humid region where minimal supplemental N is the goal

Estimating Prices for R&D Investment in the 2007 R&D Satellite Account

This paper is part of a series that provides the details behind the Bureau of Economic Analysis's (BEA) satellite account on research and development (R&D) activity. In the current work, the focus is on the theoretical underpinnings and empirical implementation of the R&D price index used to construct real R&D output. We examine four alternative price indexes. For each, we lay out the theoretical assumptions needed for the approach to be valid and examine how well the approach works in practice. We then compare these four alternative price indexes and explain the choice of our preferred price index.

2008 Survey of the Performance of American Elections: Final Report

Analyzes results of a survey on the 2008 elections voting experience, voter confidence in the system, reasons for not voting, and support for reform proposals. Examines how age, race/ethnicity, and length of residency affect voters' experiences

Justice and Law Journals

What is the role for a law journal in advancing justice? What is the role of a justice-minded practitioner in furthering legal scholarship? And what is the intersection—practically and normatively—for law journals, legal scholars, practitioners, and justice? This brief Article attempts to lay a foundation for answering these important, but oft-neglected, questions. In the following conversation, a frequent contributor to the Michigan Journal of Race & Law (MJRL) and a former Editor-in-Chief of the Journal posit some ideas on how legal scholarship engages with justice, and how race-conscious practitioners can interact with race-conscious legal scholars

Effect of Some Performance Indicators of Mathematics in the Nalerigu Senior High School

This study employed the multivariate analysis of variance (MANOVA) procedure to examine the influence of students’ sex, age and course of study (department) on mathematics performance in Nalerigu Senior High School of the East Mampurisi district in the Northern of Ghana. The results showed that male students perform better on the average for all the mathematics performance indicators (understanding, knowledge and perception). The MANOVA analysis revealed that students performance in mathematics do not differ across sex (gender) and age group. The results however showed that there was significant difference in performance of mathematics across course of study (department). However, the univariate analysis of variance (ANOVA) results revealed that there was no sex difference in understanding and knowledge of mathematics while significant differences exist in perception of mathematics among male and female students. Further, the study revealed a significant difference in students understanding and knowledge in mathematics and no bias in perception of mathematics among students age. The study therefore recommended that, the Ministry of Education, school managements and other stakeholders such as Non Governmental Organizations should sensitize students to discard beliefs and practices that prohibit effective participation of female students which result to poor performance in mathematics

Chemically activated reactions on the C7H5 energy surface: Propargyl + diacetylene, i-C5H3 + acetylene, and n-C5H3 + acetylene

This study uses computational chemistry and statistical reaction rate theory to investigate the chemically activated reaction of diacetylene (butadiyne, C4H2) with the propargyl radical (C •H2CCH) and the reaction of acetylene (C 2H2) with the i-C5H3 (CH 2CCCC•H) and n-C5H3 (CHCC •HCCH) radicals. A detailed G3SX-level C7H 5 energy surface demonstrates that the C3H3 + C4H2 and C5H3 + C2H 2 addition reactions proceed with moderate barriers, on the order of 10 to 15 kcal mol-1, and form activated open-chain C 7H5 species that can isomerize to the fulvenallenyl radical with the highest barrier still significantly below the entrance channel energy. Higher-energy pathways are available leading to other C 7H5 isomers and to a number of C7H4 species + H. Rate constants in the large multiple-well (15) multiple-channel (30) chemically activated system are obtained from a stochastic solution of the one-dimensional master equation, with RRKM theory for microcanonical rate constants. The dominant products of the C4H2 + C 3H3 reaction at combustion-relevant temperatures and pressures are i-C5H3 + C2H2 and CH2CCHCCCCH + H, along with several quenched C7H 5 intermediate species below 1500 K. The major products in the n-C5H3 + C2H2 reaction are i-C 5H3 + C2H2 and a number of C 7H4 species + H, with C7H5 radical stabilization at lower temperatures. The i-C5H3 + C 2H2 reaction predominantly leads to C7H 4 + H and to stabilized C7H5 products. The title reactions may play an important role in polycyclic aromatic hydrocarbon (PAH) formation in combustion systems. The C7H5 potential energy surface developed here also provides insight into several other important reacting gas-phase systems relevant to combustion and astrochemistry, including C2H + the C3H4 isomers propyne and allene, benzyne + CH, benzene + C(3P), and C7H5 radical decomposition, for which some preliminary analysis is presented. © 2011 the Owner Societies