Analysis of the die casting process by design of experiments

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Strong variability of the coronal line region in NGC 5548

We present the second extensive study of the coronal line variability in an active galaxy. Our data set for the well-studied Seyfert galaxy NGC 5548 consists of five epochs of quasi-simultaneous optical and near-infrared spectroscopy spanning a period of about five years and three epochs of X-ray spectroscopy overlapping in time with it. Whereas the broad emission lines and hot dust emission varied only moderately, the coronal lines varied strongly. However, the observed high variability is mainly due to a flux decrease. Using the optical [FeVII] and X-ray OVII emission lines we estimate that the coronal line gas has a relatively low density of n~10^3/cm^3 and a relatively high ionisation parameter of log U~1. The resultant distance of the coronal line gas from the ionising source of about eight light years places this region well beyond the hot inner face of the dusty torus. These results imply that the coronal line region is an independent entity. We find again support for the X-ray heated wind scenario of Pier & Voit; the increased ionising radiation that heats the dusty torus also increases the cooling efficiency of the coronal line gas, most likely due to a stronger adiabatic expansion. The much stronger coronal line variability of NGC 5548 relative to that of NGC 4151 can also be explained within this picture. NGC 5548 has much stronger coronal lines relative to the low ionisation lines than NGC 4151 indicating a stronger wind, in which case a stronger adiabatic expansion of the gas and so fading of the line emission is expected.Comment: 10 pages, 6 figures; accepted for publication in MNRAS. arXiv admin note: substantial text overlap with arXiv:1501.0292

Variability of the coronal line region in NGC 4151

We present the first extensive study of the coronal line variability in an active galaxy. Our data set for the nearby source NGC 4151 consists of six epochs of quasi-simultaneous optical and near-infrared spectroscopy spanning a period of about eight years and five epochs of X-ray spectroscopy overlapping in time with it. None of the coronal lines showed the variability behaviour observed for the broad emission lines and hot dust emission. In general, the coronal lines varied only weakly, if at all. Using the optical [Fe VII] and X-ray O VII emission lines we estimate that the coronal line gas has a relatively low density of n~10^3 cm^-3 and a relatively high ionisation parameter of log U~1. The resultant distance of the coronal line gas from the ionising source is about two light years, which puts this region well beyond the hot inner face of the obscuring dusty torus. The high ionisation parameter implies that the coronal line region is an independent entity rather than part of a continuous gas distribution connecting the broad and narrow emission line regions. We present tentative evidence for the X-ray heated wind scenario of Pier & Voit. We find that the increased ionising radiation that heats the dusty torus also increases the cooling efficiency of the coronal line gas, most likely due to a stronger adiabatic expansion.Comment: 12 pages, 9 figures; accepted by MNRA

Chemotaxis of Arbacia punctulata spermatozoa to resact, a peptide from the egg jelly layer

Resact, a peptide of known sequence isolated from the jelly layer of Arbacia punctulata eggs, is a potent chemoattractant for A. punctulata spermatozoa. The chemotactic response is concentration dependent, is abolished by pretreatment of the spermatozoa with resact, and shows an absolute requirement for millimolar external calcium. A. punctulata spermatozoa do not respond to speract, a peptide isolated from the jelly layer of Strongylocentrotus purpuratus eggs. This is the first report of animal sperm chemotaxis in response to a defined egg-derived molecule

A determination of the weight enumerator of the code of the projective plane of order 5

We determine the weight enumerator of the code of the projective plane of order 5 by hand. The main tools used are a version of Gleason's theorem on the enumerators of self-dual codes and geometric descriptions of codewords of low weight. This paper contains the full details of the companion paper [9] the outlined our results

Distributed computing system with dual independent communications paths between computers and employing split tokens

This is a distributed computing system providing flexible fault tolerance; ease of software design and concurrency specification; and dynamic balance of the loads. The system comprises a plurality of computers each having a first input/output interface and a second input/output interface for interfacing to communications networks each second input/output interface including a bypass for bypassing the associated computer. A global communications network interconnects the first input/output interfaces for providing each computer the ability to broadcast messages simultaneously to the remainder of the computers. A meshwork communications network interconnects the second input/output interfaces providing each computer with the ability to establish a communications link with another of the computers bypassing the remainder of computers. Each computer is controlled by a resident copy of a common operating system. Communications between respective ones of computers is by means of split tokens each having a moving first portion which is sent from computer to computer and a resident second portion which is disposed in the memory of at least one of computer and wherein the location of the second portion is part of the first portion. The split tokens represent both functions to be executed by the computers and data to be employed in the execution of the functions. The first input/output interfaces each include logic for detecting a collision between messages and for terminating the broadcasting of a message whereby collisions between messages are detected and avoided

Student and Faculty Perceptions of the Quality of Online Learning Experiences

Some faculty members are reluctant to offer online courses because of significant concerns relative to the impact of such formats on the quality of instruction, learning, and participant interaction. Faculty members from The University of Southern Mississippi implemented synchronous interactive online instruction (SIOI) in the spring of 2007. This article explores the rationale for use of the particular technology, faculty conclusions regarding implementation of the technology, and the impact of the technology on instruction and learning. Comparisons by students of the quality of the learning experience in this environment with the quality of learning in face-to-face and asynchronous online learning environments were also analyzed. The study finds that instructors and students view SIOI favourably. The mean student ratings for the dimensions of instructional quality were the same for SIOI and face-to-face course formats in all but one dimension, but mean ratings for SIOI and face-to-face formats were consistently higher than those for asynchronous online instruction. The single exception was for the dimension, ease of access to the course; the SIOI and asynchronous online formats were rated higher than the face-to-face format in this quality dimension. These findings suggest that it is possible to achieve levels of effectiveness in an online instructional format similar to those that are realized in face-to-face delivery. However, there is slight, though not statistically significant, evidence of concern about the quality of student collaboration in SIOI-enabled courses. Thus, instructors will need to capitalize on available mechanisms for interaction and collaboration

Student and faculty perceptions of the quality of online learning experiences

Some faculty members are reluctant to offer online courses because of significant concerns relative to the impact of such formats on the quality of instruction, learning, and participant interaction. Faculty members from The University of Southern Mississippi implemented synchronous interactive online instruction (SIOI) in the spring of 2007. This article explores the rationale for use of the particular technology, faculty conclusions regarding implementation of the technology, and the impact of the technology on instruction and learning. Comparisons by students of the quality of the learning experience in this environment with the quality of learning in face-to-face and asynchronous online learning environments were also analyzed.The study finds that instructors and students view SIOI favourably. The mean student ratings for the dimensions of instructional quality were the same for SIOI and face-to-face course formats in all but one dimension, but mean ratings for SIOI and face-to-face formats were consistently higher than those for asynchronous online instruction. The single exception was for the dimension, ease of access to the course; the SIOI and asynchronous online formats were rated higher than the face-to-face format in this quality dimension. These findings suggest that it is possible to achieve levels of effectiveness in an online instructional format similar to those that are realized in face-to-face delivery. However, there is slight, though not statistically significant, evidence of concern about the quality of student collaboration in SIOI-enabled courses. Thus, instructors will need to capitalize on available mechanisms for interaction and collaboration