Ultra-stable, low phase noise dielectric resonator stabilized oscillators for military and commercial systems

EPSD has designed, fabricated and tested, ultra-stable, low phase noise microwave dielectric resonator oscillators (DRO's) at S, X, Ku, and K-bands, for potential application to high dynamic range and low radar cross section target detection radar systems. The phase noise and the temperature stability surpass commercially available DROs. Low phase noise signals are critical for CW Doppler radars, at both very close-in and large offset frequencies from the carrier. The oscillators were built without any temperature compensation techniques and exhibited a temperature stability of 25 parts per million (ppm) over an extended temperature range. The oscillators are lightweight, small and low cost compared to BAW & SAW oscillators, and can impact commercial systems such as telecommunications, built-in-test equipment, cellular phone and satellite communications systems. The key to obtaining this performance was a high Q factor resonant structure (RS) and careful circuit design techniques. The high Q RS consists of a dielectric resonator (DR) supported by a low loss spacer inside a metal cavity. The S and the X-band resonant structures demonstrated loaded Q values of 20,300 and 12,700, respectively

Does the Plaintiff Matter?: An Empirical Analysis of Lead Plaintiffs in Securities Class Actions

With the enactment of the Private Securities Litigation Reform Act of 1995 (PSLR) the U.S. Congress introduced sweeping substantive and procedural reforms for securities class actions. A central provision of the Act is the lead plaintiff provision, which creates a rebuttable presumption that the investor with the largest financial interest in a securities fraud class action should be appointed the lead plaintiff for the suit. The lead plaintiff provision was adopted to encourage a class member with a large financial stake to become the class representative. Congress expected that such a plaintiff would actively monitor the conduct of a securities fraud class action so as to reduce the litigation agency costs that may arise when class counsel\u27s interests diverge from those of the shareholder class. Now, more than ten years after the enactment of the lead plaintiff provision, the claim that the lead plaintiff, and particularly the lead plaintiff that is an institutional investor, is a more effective monitor of class counsel in securities fraud class actions continues to be intuitively appealing, but remains unproven. In this study, Professors Cox and Thomas inquire anecdotally and empirically whether the lead plaintiff provision has performed as projected. The anecdotal evidence they uncover is mixed: in some instances demonstrating the virtues of the lead plaintiff provision, while in others showing that the provision has encountered difficulties, including hesitance among institutional lead plaintiffs to take on the burden of serving as lead plaintiff (though recently more institutional investors are taking on the role of lead plaintiff) and allegations of pay-to-play schemes between plaintiffs\u27 law firms and potential lead plaintiffs. Professors Cox and Thomas then conduct a series of statistical analyses of the lead plaintiff provision\u27s costs and benefits. Surprisingly, their results indicate that the ratio of settlement amounts to estimated provable losses in securities class actions---the most important indicator of whether investors have been compensated for their damages---has been lower since the passage of the PSLRA and that settlement size has not increased since the passage of PSLRA. However, they also find that the presence of an institutional investor increases the dollar amount of settlements in those cases in which they appear, suggesting that the current trend for institutional investors to be lead plaintiffs in securities class actions will positively affect average settlement size in such actions in the future. Their analysis also sheds new light on the relative impacts other types of lead plaintiffs, such as individuals versus an aggregation of individuals, have on the outcome of settlements. They conclude with a discussion of the policy implications of their findings

SEC Enforcement Heuristics: An Empirical Inquiry

This Article examines the overlap between SEC securities enforcement actions and private securities fraud class actions. We begin with an overview of data concerning all SEC enforcement actions from 1997 to 2002. We find that the volume of SEC enforcement proceedings is relatively modest. We next examine the scope of the recently enacted Fair Fund provision that authorizes the SEC to designate civil penalties it recovers from defendants to benefit defrauded private investors. We conclude that this provision offers only limited potential relief for private investors. We complete this Part of the Article with an analysis of the serious resource limitations faced by the SEC. The second portion of the Article contains an empirical analysis of the determinants of SEC enforcement actions and the overlap of private fraud suits and SEC enforcement proceedings. Using bivariate analysis, we find that (1) private suits with parallel SEC actions settle for significantly more than private suits without such proceedings; (2) SEC enforcement actions target significantly smaller companies than private actions alone; (3) private cases with parallel SEC actions take substantially less time to settle than other private cases; and (4) private cases with parallel SEC actions have significantly longer class periods than other private actions. Finally, we create a model for estimating damages to compare settlement ratios in cases with parallel SEC actions to those in private actions. We find that one-fourth of all the private class action settlements occurring in suits that yield less than 10 percent of provable losses are settled for less than 2 percent of provable losses, but that there are no private actions with parallel SEC suits with such small settlements. In the final Part of the Article, we conduct a multivariate regression analysis of the determinants of when SEC enforcement actions are filed. We find that the most highly significant determinant of SEC actions is financial distress. Estimated losses do not appear to be a statistically significant factor in the SEC\u27s decision to file these suits

Automated Hate Speech Detection and the Problem of Offensive Language

A key challenge for automatic hate-speech detection on social media is the separation of hate speech from other instances of offensive language. Lexical detection methods tend to have low precision because they classify all messages containing particular terms as hate speech and previous work using supervised learning has failed to distinguish between the two categories. We used a crowd-sourced hate speech lexicon to collect tweets containing hate speech keywords. We use crowd-sourcing to label a sample of these tweets into three categories: those containing hate speech, only offensive language, and those with neither. We train a multi-class classifier to distinguish between these different categories. Close analysis of the predictions and the errors shows when we can reliably separate hate speech from other offensive language and when this differentiation is more difficult. We find that racist and homophobic tweets are more likely to be classified as hate speech but that sexist tweets are generally classified as offensive. Tweets without explicit hate keywords are also more difficult to classify.Comment: To appear in the Proceedings of ICWSM 2017. Please cite that versio

Stable Gaussian Process based Tracking Control of Lagrangian Systems

High performance tracking control can only be achieved if a good model of the dynamics is available. However, such a model is often difficult to obtain from first order physics only. In this paper, we develop a data-driven control law that ensures closed loop stability of Lagrangian systems. For this purpose, we use Gaussian Process regression for the feed-forward compensation of the unknown dynamics of the system. The gains of the feedback part are adapted based on the uncertainty of the learned model. Thus, the feedback gains are kept low as long as the learned model describes the true system sufficiently precisely. We show how to select a suitable gain adaption law that incorporates the uncertainty of the model to guarantee a globally bounded tracking error. A simulation with a robot manipulator demonstrates the efficacy of the proposed control law.Comment: Please cite the conference paper. arXiv admin note: text overlap with arXiv:1806.0719

Human Factors in Automated and Robotic Space Systems: Proceedings of a symposium. Part 1

Human factors research likely to produce results applicable to the development of a NASA space station is discussed. The particular sessions covered in Part 1 include: (1) system productivity -- people and machines; (2) expert systems and their use; (3) language and displays for human-computer communication; and (4) computer aided monitoring and decision making. Papers from each subject area are reproduced and the discussions from each area are summarized

The Effects of Freewriting on High School Students’ Attitudes Toward Writing

This paper investigates the hypothesis that freewriting, when used as part of the writing process, will lead to more positive attitudes toward writing in a sample of advanced tenth grade students. An additional issue focuses on the level of positive attitudes of males when compared to females. Two intact classrooms taught by one teacher wrote weekly papers. The experimental group wrote freely, while the control group was restricted in topic choice, length and form of their writing. The experimental group received positive comments on the content of their writing, but the control group received standard error corrections on their writing. The subjects responded to an attitude instrument as pretest and posttest measures. The experimental group showed no significant increase in positive attitudes toward writing. Girls in both the experimental and comparison groups showed no more attitudes toward writing than pretesting or at post testing

The Epistemology of Ignorance

Nancy Tuana explores the nature of the epistemology of ignorance in her essay titled, Coming to Understand: Orgasm and the Epistemology of Ignorance . She describes our current epistemologies as too narrow, lacking in scope and truth because they focus only on the knowledge we have and ignore the knowledge we don’t have. If we want to more fully understand how our culture produces information, “we must also understand that practices that account for not knowing, that is, our lack of knowledge about a phenomena or, in some cases, an account of the practices that resulted in a group unlearning what was once a realm of knowledge”. Essentially and somewhat paradoxically, if we want to understand how we have knowledge, we have to know what we don’t know, and why. The epistemology of ignorance serves to marginalize types of knowledge and erase or simply make invisible what was once and has always been available. This activity of making certain knowledge invisible contributes to the oppression of one class to those in power. It is this power dynamic that I will explore in specific relation by the science of women’s raced and classed bodies