CEO GENDER AND FIRM PERFORMANCE

Based on data collected from the Execucomp database concerning S&P 1,500 U.S. firms over the period 1992 to 2013, we evaluate whether CEO gender affects firm performance. We also examine CEO performance in terms of company risk. Our research reveals that on average the gender of the CEO has no significant effect on firm performance. Specifically, our research shows that the gender of CEO does not affect the firm risk level, and in terms of stock return, the difference is not significant between female and male CEOs. Furthermore, We divide firms into high risk and low risk groups based on their β, where β greater than one is considered high risk and β less than one is considered low risk. As a result of this analysis there is no evidence that CEO gender has a significant impact on firm performance regardless of the company risk level

A KP-mKP Hierarchy via Operators with Two Derivations

By using pseudo-differential operators containing two derivations, we extend the Kadomtsev-Petviashvili (KP) hierarchy to a certain KP-mKP hierarchy. For the KP-mKP hierarchy, we obtain its B\"{a}cklund transformations, bilinear equations of Baker-Akhiezer functions and Hirota equations of tau functions. Moreover, we show that this hierarchy is equivalent to a subhierarchy of the dispersive Whitham hierarchy associated to the Riemann sphere with its infinity point and one movable point marked

Self-organized chains of nanodots induced by an off-normal incident beam

We propose a model to show that under off-normal bombardment of an incident ion beam, a solid surface may spontaneously form nanoscale dots lining up into chains perpendicular to the incident beam direction. These dots demonstrate a highly ordered hexagonal pattern. We attribute the self-organization behavior to surface instability under concurrent surface kinetics and to a shadow effect that causes the self-alignment of dots. The fundamental mechanism may be applicable to diverse systems, suggesting an effective approach for nanofabrication

Long-term mechanical behavior of Yucca Mountain tuff and its variability

The study of the long term mechanical behavior of Yucca Mountain tuffs is important for several reasons. Long term stability of excavations will affect accessibility (e.g. for inspection purposes), and retrievability. Long term instabilities may induce loading of drip shields and/or emplaced waste, thus affecting drip shield and/or waste package corrosion. Failure of excavations will affect airflow, may affect water flow, and may affect temperature distributions. The long term mechanical behavior of “hard” rocks remains an elusive topic, loaded with uncertainties. A variety of approaches have been used to improve the understanding of this complex subject, but it is doubtful that it has reached a stage where firm predictions can be considered feasible

Experimental investigation of time dependent behavior of welded Topopah Spring Tuff

Four types of laboratory tests have been performed. Specimens were attained from four lithophysal zones of the welded Topopah Spring Tuff unit at Yucca Mountain, Nevada: upper lithophysal, middle nonlithophysal, lower lithophysal and lower nonlithophysal zones. Two types of tests are conducted to study time-dependent behavior: constant strain rate and creep tests. Sixty five specimens from the middle nonlithophysal zone were tested at six strain rates: 10 , 10 , 10 , 10 , 10 , and 10 . Test durations range from 2 seconds to 7 days. Fourteen specimens from middle nonlithophysal, lower lithophysal and lower nonlithophysal zones are creep tested by incremental stepwise loading. All the tests are conducted under uniaxial compression at room temperature and humidity. Specimens exhibit extremely brittle fracture and fail by axial splitting, and show very little dilatancy if any. It is assumed that microfracturing dominates the inelastic deformation and failure of the tuff. Nonlinear regression is applied to the results of the constant strain rate tests to estimate the relations between peak strength, peak axial strain, secant modulus and strain rate. All three these parameters decrease with a decrease of strain rate and follow power functions:σ peak= 271.37ε&0.0212 ε peak= 0.0066ε&0.0083 ES = 41985.4ε&0.015. Secant modulus is introduced mainly as a tool to analyze strain rate dependent axial strain

Understanding and Advancing the Status Quo of DDoS Defense

Two decades after the first distributed denial-of-service (DDoS) attack, the Internet remains challenged by DDoS attacks as they evolve. Not only is the scale of attacks larger than ever, but they are also harder to detect and mitigate. Nevertheless, the Internet's fundamental design, based on which machines are free to send traffic to any other machines, remains the same. This thesis reinvestigates the prior DDoS defense solutions to find less studied but critical issues in existing defense solutions. It proposes solutions to improve the input, design, and evaluation of DDoS defense. Specifically, we show why DDoS defense systems need a better view of the Internet's traffic at the autonomous system (AS) level. We use a novel attack to expose the inefficiencies in the existing defense systems. Finally, we reason why a defense solution needs a sound empirical evaluation and provide a framework that mimics real-world networks to facilitate DDoS defense evaluation. This dissertation includes published and unpublished co-authored materials

Complete Recovery of a Booked Primigravida with Hemorrhagic Stroke Due to Severe Preeclampsia

Stroke is a major contributor to morbidity and mortality during pregnancy and puerperium. Intracerebral hemorrhage (ICH), which is bleeding within the cerebral parenchyma as a result of rupture of a blood vessel, is the second most common type of stroke after ischemic stroke. We report a case of ICH due to severe preeclampsia that was suspected to have occurred shortly before cesarean section in a woman with prior normal prenatal care. She recovered completely without any neurological deficit.KEY WORDS: Complete recovery, intracerebral hemorrhage, Nigeria, preeclampsia, strok

Ion irradiation-induced bimodal surface morphology changes in InSb

High-energy ion irradiation of InSb results in the formation of bimodal surface structures, namely microscale hillock-like structures fully composed of nanoscale fibers. Analysis of the surface structures by a wide range of electron microscopy techniques reveals correlations between the irradiation conditions, such as the ion energy and fluence, and changes in the surface morphology. Sputtering effects play a key role in the integrity of the surface layer with increasing ion fluence. Possible mechanisms responsible for the morphological transformation are discussed, including both irradiation-induced and mechanical effects.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85399/1/nano10_32_325602.pd

The status change of culture and education in the traditional Chinese city landscape after the Song and Yuan Dynasty

After the Song and Yuan dynasties, the development of the imperial examination system was witnessed by the spread of the Neo-Confucianism of the Song and Ming dynasties. This was accompanied by the position of culture and education buildings in the local urban landscape system that was greatly improved, some even dominating the performance of the urban landscape. The resulted structure of the urban landscape before the Song Dynasty is described as the so-called status change of the "The Status Change of Culture and Education." Studies have shown that "The Status Change" during the Ming and Qing Dynasties could be found here and there. This work took the City of Yangzhou Prefecture in the Ming and Qing Dynasties as the research object. Starting from the background of the development of culture and education, this paper expounds the process and characteristics of such a status change during this period