Free Electron Sources and Diffraction in Time

The quantum revolution of the last century advanced synergistically with technology, for example, with control of the temporal and spatial coherence, and the polarization state of light. Indeed, experimental confirmation of the quirks of quantum theory, as originally highlighted by Einstein, Podolsky, and Rosen, through Bohm, and then Bell, have been performed with photons, i.e., electromagnetic wave packets prepared in the same quantum states. Experimental tests of quantum mechanics with matter wave packets have been limited due to challenges in preparing all of the packets with similar quantum states. While great strides have been made for trapped atoms and Bose-Einstein condensates, the technology for electron matter waves has not kept pace. In other words, electron sources typically have a low quantum degeneracy. As new techniques to control the coherence of electron wave packets are developed, new avenues to test quantum theory become available. To better understand the temporal coherence of a pulsed electron source, we have studied electron emission from metallic and semiconductor structures. Ultrafast electron emission was obtained by focusing femtosecond laser pulses on metallic nanotips and nanoribbons, as well as semiconductor shards. The various emission mechanisms from these sources were investigated in efforts to control the coherence of the emitted electron wave packets. The electronic band structure of semiconductor materials provides an additional feature in that the spin state of emitted electrons can be optically controlled. Controlling the spin polarization in a pulsed electron source could lead to a source with the highest quantum degeneracy yet achieved. The development of a quantum degenerate source of matter waves is a step toward realizing fundamental tests of quantum mechanics with electron wave packets. As quantum degenerate electron sources do not yet exist, their potential and utility remains to be explored. An ultrafast spin-polarized source of electrons is itself intriguing for studying nanoscale magnetic systems with unprecedented temporal resolution. These advancements suggest that an entirely new field of free electron quantum optics may be within our reach, with all of its possibilities open for exploration. The quantum revolution may yet have some surprises in store. Advisor: Herman Batelaa

Approaches to Enhance Driver Situational Assessment Aids

Collision warning systems encounter a fundamental trade-off between providing the driver more time in which to respond and alerting the driver unnecessarily. The probability that a driver successfully avoids a hazard increases as the driver is provided more time and distance in which to identify the hazard and execute the most effective response. However, alerting the driver at earlier, more conservative thresholds increases the probability that the alerts are unnecessary, either because sensor error has falsely identified a hazard or because the environment has changed such that a hazard is no longer a threat. Frequent unnecessary alerts degrade alert effectiveness by reducing trust in the system. The human-factors issues pertaining to a forward collision warning system (FCWS) were analyzed using an Integrated Human-Centered Systems approach, from which two design features were proposed: multi-stage alerting, which alerts the driver at a conservative early threshold, in addition to a more serious late threshold; and directional alerting, which provides the driver information regarding the location of the hazard that prompted the alert activation. Alerting the driver earlier increases the probability of a successful response by conditioning the driver to respond more effectively if and when evasive action is necessary. Directional alerting decreases the amount of time required to identify the hazard, while promoting trust in the system by informing the driver of the cause of the alert activation. The proposed design features were incorporated into three FCWS configurations, and an experiment was conducted in which drivers were equipped with the systems and placed in situations in which a collision would occur if they did not respond. Drivers who were equipped with multi-stage and directional alerting were more effective at avoiding hazardous situations than drivers who were not provided early alerting. Drivers with early alerting tended to respond earlier and more consistently, which promoted more successful responses. Subjective feedback indicates that drivers experienced high levels of acceptance, confidence, and trust in multi-stage and directional alerting.This work was funded by a grant provided through the Ford-MIT Alliance

The proliferation of conventionally-powered submarines: balancing U.S. Cruise missile diplomacy? The cases of India and Iran

The end of the Cold War has left the United States as the world's sole superpower. The ability of the United States to strike deep into the territories of most nations with impunity represents a new security threat to many nations. Defeating the U.S. military is not feasible in mostcases, but balancing the United States may be possible, especially with weapons of mass destruction (WMD). Although WMD might provide a formidable deterrent, their technical, political, and economic costs preclude most nations from ursuing them. On the other hand, modern conventionally powered submarines are easier to obtain and operate and could present a significant deterrent to U.S. military force. This thesis assesses whether the perceived threat posed by the United States has emerged as a motivation for acquiring conventionally powered submarines since the end of the Cold War. After examining the motivations behind the recent submarine acquisitions of India and Iran, this thesis presents an economic model to predict when developing nations will be able to afford submarines if they choose to acquire themhttp://archive.org/details/proliferationofc00joneLieutenant, United States NavyApproved for public release; distribution is unlimited

Seismic data acquisition at the FACT site for the CASPAR project.

Since May 2010, we have been recording continuous seismic data at Sandia's FACT site. The collected signals provide us with a realistic archive for testing algorithms under development for local monitoring of explosive testing. Numerous small explosive tests are routinely conducted around Kirtland AFB by different organizations. Our goal is to identify effective methods for distinguishing these events from normal daily activity on and near the base, such as vehicles, aircraft, and storms. In this report, we describe the recording system, and present some observations of the varying ambient noise conditions at FACT. We present examples of various common, non-explosive, sources. Next we show signals from several small explosions, and discuss their characteristic features

Affective Responses to Common Fitness Testing in College-Aged Women

Fitness testing provides awareness of discrepancy from normative standards and is a major component in most health, medical, and wellness settings. This discrepancy may have an effect on an individual’s desire to change or maintain particular health behaviors. PURPOSE: The purpose of the present study was to examine the affective responses to discrepancies from normative data across six standard fitness tests. METHODS: Forty-eight college-aged women were presented with their discrepancy from a normative standard across standard fitness tests for body fat, body shape, aerobic fitness, muscular strength, muscular endurance, and flexibility. RESULTS: Findings support previous conceptualizations on perceived discrepancies and affective responses: greater negative discrepancies from a normative standard in common fitness tests are associated with greater changes in negative feeling states. However, feeling more negative about a discrepancy does not guarantee a specific change in frustration-anger, which is theorized to relate to increased effort to reduce a discrepancy. Only three tests related to such responses, body fat (r=.46, p\u3c.01), aerobic fitness (r=.41, p\u3c.01), and muscular endurance (r=.34, p\u3c.05), perhaps due to their perceived threat to one’s global physical self-worth. CONCLUSION: Only discrepancies from body fat, aerobic fitness, and muscular endurance norms produced a change in feeling state which may in turn affect future behavior. Future research should examine how affective response could have positive or negative impacts on future behavior to reduce the perceived discrepancy, in addition to why particular discrepancies may be linked to physical self-worth, and not others