Structural plasticity and associative memory in balanced neural networks with spike-time dependent inhibitory plasticity

Peer reviewe

A Definition and Investigation of Cooperative Acquisition Programs Using Multiple Case Studies

This thesis is an exploratory study of the management of cooperative acquisition programs. The investigation focuses on defining the nature of a cooperative acquisition strategy, identifying potential problems associated with this approach, and evaluating the effectiveness of the current guidance and support structure for such programs. The desired outcome of this strategy is a common solution. The operational definition of cooperative acquisition builds on the Department of Defense definition of Joint Service Acquisition. A pilot study and literature review are used to develop a structured interview for three case studies. Analysis of these cases indicates that difficulty in resolving core requirements, and funding instability are the two major sources of problems on cooperative acquisition programs. Also, the guidance and support for cooperative acquisition programs has been slow to develop

π\pi-Electron Ferromagnetism in Metal Free Carbon Probed by Soft X-Ray Dichroism

Elemental carbon represents a fundamental building block of matter and the possibility of ferromagnetic order in carbon attracted widespread attention. However, the origin of magnetic order in such a light element is only poorly understood and has puzzled researchers. We present a spectromicroscopy study at room temperature of proton irradiated metal free carbon using the elemental and chemical specificity of x-ray magnetic circular dichroism (XMCD). We demonstrate that the magnetic order in the investigated system originates only from the carbon $\pi$-electron system.Comment: 10 pages 3 color figure

Enhancement of Jc by Hf -Doping in the Superconductor MgB2: A Hyperfine Interaction Study

Measurements of the critical current density (Jc) by magnetization and the upper critical field (Hc2) by magnetoresistance have been performed for hafnium-doped MgB2. There has been a remarkable enhancement of Jc as compared to that by ion irradiation without any appreciable decrease in Tc, which is beneficial from the point of view of applications. The irreversibility line extracted from Jc shows an upward shift. In addition, there has been an increase in the upper critical field which indicates that Hf partially substitutes for Mg. Hyperfine interaction parameters obtained from time differential perturbed angular correlation (TDPAC) measurements revealed the formation of HfB and HfB2 phases along with the substitution of Hf. A possible explanation is given for the role of these species in the enhancement of Jc in MgB2 superconductor

A user-friendly fully digital TDPAC-spectrometer

A user-friendly fully digital TDPAC-spectrometer with six detectors and fast digitizers using Field Programmable Gate Arrays is described and performance data are given

Beyond the Ice

Leadership is a management tool to direct effective achievement of goals. Historical investigation can provide a valuable lens for the study of leadership styles. To that end, this study examines the disparate approaches of Roald Amundsen and Robert Scott as they raced to be the first explorer to reach the South Pole. The objective of this study is to analyze the leadership techniques used in these expeditions, and to determine how they shaped the outcome of each. The process of tacit knowledge and experience coalesce and foster both leadership and action that is not only communication-oriented and value-driven, but also rooted in growth mindset and reflexivity. Both of these concepts proved to be imperative to the success of both Amundsen and Scott’s expeditions. Ultimately, the experiences, choices, and eventual fate of polar explorers Roald Amundsen and Robert Scott provide a unique view of the human endeavor that holds valuable lessons for leaders in a variety of professional settings

The role of hydrogen in room-temperature ferromagnetism at graphite surfaces

We present a x-ray dichroism study of graphite surfaces that addresses the origin and magnitude of ferromagnetism in metal-free carbon. We find that, in addition to carbon $\pi$ states, also hydrogen-mediated electronic states exhibit a net spin polarization with significant magnetic remanence at room temperature. The observed magnetism is restricted to the top $\approx$10 nm of the irradiated sample where the actual magnetization reaches $\simeq 15$ emu/g at room temperature. We prove that the ferromagnetism found in metal-free untreated graphite is intrinsic and has a similar origin as the one found in proton bombarded graphite.Comment: 10 pages, 5 figures, 1 table, submitted to New Journal of Physic

Students\u27 Emotions for Achievement and Technology Use in Synchronous Hybrid Graduate Programmes: A Control-Value Approach

Synchronous hybrid delivery (simultaneously teaching on-campus and online students using web conferencing) is becoming more common; however, little is known about how students experience emotions in this learning environment. Based on Pekrun’s (2006) control-value theory of emotions, the dual purpose of this study was first to compare synchronous hybrid students who attend online versus on-campus in terms of control, value, emotions and perceived success and second to compare students’ degree of emotional activation in the domains of programme achievement and technology use. Survey data from 101 graduate business students revealed that online students reported significantly higher levels of technology-related anger, anxiety and helplessness. Furthermore, in compar- ison to their on-campus counterparts, online students more clearly separated their emotions in terms of programme achievement and technology use. Emotions related significantly to students’ perceived success for both programme achieve- ment and technology use, and mediated the effects of control and value appraisals on perceived success