Proportions of r-regular elements in finite classical groups

For a prime $r$, we obtain lower bounds on the proportion of $r$-regular elements in classical groups and show that these lower bounds are the best possible lower bounds that do not depend on the order of the defining field. Along the way, we also provide new upper bounds and answer some open questions of the first author, P\'{a}lfy and Saxl.Comment: 22 page

The Impact on U.K. Acquirers of Domestic, Cross-border, Public and Private Acquisitions

We examine the announcement and post-acquisition share returns of 4,000 acquisitions by U.K. public firms during 1984-1998. We include acquisitions of domestic and cross-border targets, and of both publicly quoted and privately held targets. In acquisitions of domestic public targets, abnormal returns are negative over both the announcement and post-acquisition period. In acquisitions of cross-border public targets, abnormal returns are zero over the announcement period but negative over the post-acquisition period. In contrast, acquisitions of both domestic and cross-border private targets result in positive announcement returns and zero long run returns. The main difference between private and public acquisitions is that glamour acquirers experience negative announcement and long run returns in public acquisitions, whereas glamour acquirers do not under-perform in private acquisitions. Furthermore, whereas the under-performance of domestic public acquisitions is limited to acquirers using non-cash methods of payment, acquirers of domestic private targets that use non-cash methods do not under-perform. Overall, cross-border acquisitions result in lower announcement and long run returns than domestic acquisitions. In cross-border acquisitions involving high?tech firms both announcement and long run returns are positive, whilst non-high-tech cross-border acquisitions experience zero announcement returns followed by negative long run performance. Our results also suggest that, in cross-border acquisitions, the national cultural difference between the bidder and target countries has a significantly negative impact on long run returns. This paper replaces WP214.Mergers and acquisitions; acquirer share returns; Cross-border targets; private targets

The development of a test harness for biometric data collection and validation

Biometric test reports are an important tool in the evaluation of biometric systems, and therefore the data entered into the system needs to be of the highest integrity. Data collection, especially across multiple modalities, can be a challenging experience for test administrators. They have to ensure that the data are collected properly, the test subjects are treated appropriately, and the test plan is followed. Tests become more complex as the number of sensors are increased, and therefore it becomes increasingly important that a test harness be developed to improve the accuracy of the data collection. This paper describes the development of a test harness for a complex multi-sensor, multi-visit data collection, and explains the processes for the development of such a harness. The applicability of such a software package for the broader biometric community is also considered

A new sighting study for the fixed concentration procedure to allow for gender differences

The fixed concentration procedure (FCP) has been proposed as an alternative to the median lethal concentration (LC50) test (organisation for economic co-operation and development (OECD) test guideline [TG] 403) for the assessment of acute inhalation toxicity. The FCP tests animals of a single gender (usually females) at a number of fixed concentration levels in a sequential fashion. It begins with a sighting study that precedes the main FCP study and is used to determine the main study starting concentration. In this paper, we propose a modification to the sighting study and suggest that it should be conducted using both male and female animals, rather than just animals of a single gender. Statistical analysis demonstrates that, when females are more sensitive, the new procedure is likely to give the same classification as the original FCP, whereas, if males are more sensitive, the new procedure is much less likely to lead to incorrect classification into a less toxic category. If there is no difference in the LC50 for females and males, the new procedure is slightly more likely to classify into a more stringent class than the original FCP. Overall, these results show that the revised sighting study ensures gender differences in sensitivity do not significantly impact on the performance of the FCP, supporting its use as an alternative test method for assessing acute inhalation toxicity

A statistical evaluation of the effects of gender differences in assessment of acute inhalation toxicity

Acute inhalation toxicity of chemicals has conventionally been assessed by the median lethal concentration (LC50) test (organisation for economic co-operation and development (OECD) TG 403). Two new methods, the recently adopted acute toxic class method (ATC; OECD TG 436) and a proposed fixed concentration procedure (FCP), have recently been considered, but statistical evaluations of these methods did not investigate the influence of differential sensitivity between male and female rats on the outcomes. This paper presents an analysis of data from the assessment of acute inhalation toxicity for 56 substances. Statistically significant differences between the LC50 for males and females were found for 16 substances, with greater than 10-fold differences in the LC50 for two substances. The paper also reports a statistical evaluation of the three test methods in the presence of unanticipated gender differences. With TG 403, a gender difference leads to a slightly greater chance of under-classification. This is also the case for the ATC method, but more pronounced than for TG 403, with misclassification of nearly all substances from Globally Harmonised System (GHS) class 3 into class 4. As the FCP uses females only, if females are more sensitive, the classification is unchanged. If males are more sensitive, the procedure may lead to under-classification. Additional research on modification of the FCP is thus proposed

Initial in vitro screening approach to investigate the potential health and environmental hazards of Envirox™ – a nanoparticulate cerium oxide diesel fuel additive

Nanotechnology is the new industrial revolution of the 21st Century as the various processes lead to radical improvements in medicine, manufacturing, energy production, land remediation, information technology and many other everyday products and applications. With this revolution however, there are undoubted concerns for health, safety and the environment which arise from the unique nature of materials and processes at the nanometre scale

Radiostereometric Evaluation of Tendon Elongation After Distal Biceps Repair.

BACKGROUND: Operative repair of distal biceps tendon ruptures has shown successful outcomes. However, little is known about the amount of tendon or repair site lengthening after repair. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate distal biceps tendon repair via intratendinous radiostereometric analysis to analyze tendon lengthening at different time intervals of healing. The hypothesis was that there is significant lengthening after repair. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Eleven patients with distal biceps ruptures requiring operative repair were recruited. During repair, two 2-mm tantalum beads with laser-etched holes were sutured to the distal biceps tendon. Beads were evaluated via computed tomography scans immediately postoperatively and at 16 weeks. Radiographs were obtained at time 0 and then at 4, 8, and 16 weeks postoperatively. Measurements were made using the button-to-bead and bead-to-bead distances to assess repair site elongation as well as tendon elongation over time. After final follow-up, patients filled out the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire and underwent ultrasound to confirm the integrity of the tendon. RESULTS: Ten patients had complete ruptures, with 1 having a partial rupture that underwent completion of the tear and subsequent repair. All patients showed statistically significant lengthening after surgery. The mean amount of tendon lengthening after surgery was 22.8 mm (range, 11.2-30.9 mm; P \u3c .05), and the repair site lengthened a mean 17.0 mm (range, 9.6-30.6 mm; P \u3c .05) from surgery to final follow-up. The greatest change in lengthening was noted between time 0 and week 4 (mean, 11.3 mm; P \u3c .05), with the least amount of lengthening between weeks 8 and 16 (mean, 2.6 mm; P \u3c .05). The mean DASH score was 11.2. Final ultrasound evaluations found all tendons to be in continuity. CONCLUSION: All patients undergoing distal biceps tendon repair have significant elongation after surgery, with the greatest amount of lengthening seen in the early postoperative period