Microlensing of Broad Absorption Line Quasars

The physical nature of the material responsible for the high--velocity, broad-absorption line features seen in a small fraction of quasar spectra has been the subject of debate since their discovery. This has been especially compounded by the lack of observational probes of the absorbing region. In this paper we examine the role of ``microlenses'' in external galaxies on observed variability in the profiles of broad absorption lines in multiply-imaged quasars. Utilizing realistic models for both the broad absorption line region and the action of an ensemble of microlensing masses, we demonstrate that stars at cosmological distances can provide an important probe of the physical state and structure of material at the heart of these complex systems. Applying these results to the macrolensed BAL quasar system, H1413+117, the observed spectral variations are readily reproduced, but without the fine-tuning requirements of earlier studies which employ more simplistic models.Comment: 7 pages, 4 figures (included), Latex (mn.sty), Submitted to MNRA

Dynamical mass of the O-type supergiant in Zeta Orionis A

A close companion of Zeta Orionis A was found in 2000 with the Navy Precision Optical Interferometer (NPOI), and shown to be a physical companion. Because the primary is a supergiant of type O, for which dynamical mass measurements are very rare, the companion was observed with NPOI over the full 7-year orbit. Our aim was to determine the dynamical mass of a supergiant that, due to the physical separation of more than 10 AU between the components, cannot have undergone mass exchange with the companion. The interferometric observations allow measuring the relative positions of the binary components and their relative brightness. The data collected over the full orbital period allows all seven orbital elements to be determined. In addition to the interferometric observations, we analyzed archival spectra obtained at the Calar Alto, Haute Provence, Cerro Armazones, and La Silla observatories, as well as new spectra obtained at the VLT on Cerro Paranal. In the high-resolution spectra we identified a few lines that can be associated exclusively to one or the other component for the measurement of the radial velocities of both. The combination of astrometry and spectroscopy then yields the stellar masses and the distance to the binary star. The resulting masses for components Aa of 14.0 solar masses and Ab of 7.4 solar masses are low compared to theoretical expectations, with a distance of 294 pc which is smaller than a photometric distance estimate of 387 pc based on the spectral type B0III of the B component. If the latter (because it is also consistent with the distance to the Orion OB1 association) is adopted, the mass of the secondary component Ab of 14 solar masses would agree with classifying a star of type B0.5IV. It is fainter than the primary by about 2.2 magnitudes in the visual. The primary mass is then determined to be 33 solar masses

Effective heavy-light meson energies in small-volume quenched QCD

We study effective energies of heavy-light meson correlation functions in lattice QCD and a small volume of (0.2 fm)^4 to non-perturbatively calculate their dependence on the heavy quark mass in the continuum limit. Our quenched results obtained here constitute an essential intermediate step of a first fully non-perturbative computation of the b-quark's mass in the static approximation that has recently been presented as an application of a new proposal to non-perturbatively renormalize the Heavy Quark Effective Theory. The renormalization constant and the improvement coefficients relating the renormalized current and subtracted quark mass are determined in the relevant parameter region at weak couplings, which allows to perform the numerical simulations at several, precisely fixed values of the renormalization group invariant heavy quark mass in a range from 3 GeV to 15 GeV.Comment: 24 pages including figures and tables, latex2e; version published in JHEP, small additions, results unchange

An Information Management Protocol to Control Routing and Clustering in Sensor Networks

In this paper, we develop and analyze a novel clustering protocol, Decentralized Energy Efficient cluster Propagation (DEEP), that attempts to manage the communication of data while minimizing energy consumption across the sensor networks. We also develop an Inter-Cluster Routing protocol (ICR) that is compatible with the proposed clustering technique. DEEP takes advantage of the multi-rate capabilities of 802.11a, b, g technologies by elevating the data rate to higher levels for shorter transmission ranges. This approach reduces the energy consumption by lowering the transmission time. Protocol DEEP starts with an initial cluster head and gradually forms clusters throughout the network by controlling the geographical dimensions of clusters and distribution of cluster heads in order to conserve energy and prolong network lifetime. Furthermore, due to the balanced load, protocol overhead caused by unnecessary frequent re-clustering is eradicated. Our simulation results demonstrate that DEEP distributes energy consumption approximately 8 times better than an existing clustering scheme, LEACH. In addition, DEEP substantially reduces total data communication and route setup energy consumption in the network compared to LEACH

LED TV IN THE CLASSROOM: IT’S ACCEPTABILITY AND EFFECTIVENESS IN THE PHILIPPINES

This study intends to surface the effects of using LED TV in the classroom utilizing a mixed method of quantitative to analyze teachers’ acceptability; and qualitative through phenomenology to describe the essence of the live-experienced of teachers; and phenomenography to structure the effect of LED TV in the learning of the students. Through validated researcher acceptability survey questionnaire, semi-structured interview guide, focus group discussion anchored in the Unified Theory of Acceptance and Use of Technology and Technology Acceptances Model (Kolog et al., 2015), and the richness of the data gathered, this study surfaced that the use of LED TV in the classroom is an effective and useful educational-technological tool, for it creates various effects both to teachers and students. With the use of LED TV, teachers became competent, confident, and effective teachers

Poultry for the Locker

How\u27s the best way to prepare poultry for freezing? We\u27ve been working on this problem for about 10 years at the Iowa Station. Other states have been studying it too. This story will tell you some of the things we have learned about getting the birds ready for freezing and storing

Impact of ERP implementation on the quality of work life of users: A sub-Saharan African study

ERP implementations have a disruptive impact on users and in sub-Saharan African (SSA) countries are more problematic than in developed countries. Extant ERP literature has not focused on the impact of implementations on users work life. Therefore this research aimed to confirm this impact on SSA users’ work life. A theoretical framework and survey was developed from Dooyeweerd’s “Down-To-Earth” aspects and the Easton and Van Laar Work-Related Quality of Life scale. Responses from users from 7 countries working for one case organisation were analysed. The significant effect of an ERP implementation on work life quality was confirmed. Cultural differences were also confirmed. The factors mostly accounting for work life quality impact were skills development and an improvement in working conditions due to a reduction in corruption pressure. The framework and research instrument can be used by organisations to assess the impact of an ERP implementation on user work life quality