Prediction of the Spectrum of a Digital Delta–Sigma Modulator Followed by a Polynomial Nonlinearity

This paper presents a mathematical analysis of the power spectral density of the output of a nonlinear block driven by a digital delta-sigma modulator. The nonlinearity is a memoryless third-order polynomial with real coefficients. The analysis yields expressions that predict the noise floor caused by the nonlinearity when the input is constant

Improving understanding of website privacy policies

Machine-readable privacy policies have been developed to help reduce user effort in understanding how websites will use personally identifiable information (PII). The goal of these policies is to enable the user to make informed decisions about the disclosure of personal information in web-based transactions. However, these privacy policies are complex, requiring that a user agent evaluate conformance between the user’s privacy preferences and the site’s privacy policy, and indicate this conformance information to the user. The problem addressed in this thesis is that even with machine-readable policies and current user agents, it is still difficult for users to determine the cause and origin of a conflict between privacy preferences and privacy policies. The problem arises partly because current standards operate at the page level: they do not allow a fine-grained treatment of conformance down to the level of a specific field in a web form. In this thesis the Platform for Privacy Preferences (P3P) is extended to enable field-level comparisons, field-specific conformance displays, and faster access to additional field-specific conformance information. An evaluation of a prototype agent based on these extensions showed that they allow users to more easily understand how the website privacy policy relates to the user’s privacy preferences, and where conformance conflicts occur

Medium to long-term outcome of thoracoscapular arthrodesis with screw fixation for facioscapulohumeral muscular dystrophy

Background: Shoulder girdle muscle weakness is the most constant feature of facioscapulohumeral muscular dystrophy and leads to scapular winging. Mechanical fixation of the scapula to the thoracic wall provides a stable fulcrum on which the deltoid muscle can exert its action on the humerus. The aim of this study was to evaluate the medium to long-term outcome of thoracoscapular arthrodesis with screw fixation (the modified Howard-Copeland technique). Methods: All patients with facioscapulohumeral dystrophy who underwent thoracoscapular arthrodesis with screw fixation and bone-grafting from July 1997 to July 2010 were retrospectively reviewed. Preoperative and postoperative clinical assessment included active shoulder elevation, the Constant score, a patient satisfaction score, and cosmetic satisfaction. Union was determined both clinically and radiographically. Results: Thoracoscapular arthrodesis was performed in thirty-five shoulders in twenty-four patients; eleven patients underwent bilateral procedures. The principal study group consisted of thirty-two shoulders in twenty-one patients with a minimum follow-up of twenty-four months (Mean, eighty-eight months; range, twenty-four to 174 months). The mean Constant score increased from 30 (range, 17 to 41) preoperatively to 61 (range, 30 to 90) postoperatively. The mean satisfaction score increased from 1 (range, 0 to 4) to 8.4 (range, 4 to 10). Early complications consisted of one pneumothorax, one superficial wound infection, and four early failures, two of which were associated with noncompliance with the postoperative regimen. Late complications consisted of one posttraumatic fracture resulting in loosening and one painful nonunion; both were treated successfully with revision. Conclusions: Thoracoscapular arthrodesis with screw fixation prevented scapular winging and improved short-term and long-term shoulder function in patients with facioscapulohumeral dystrophy. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence

Petawatt laser absorption bounded

The interaction of petawatt ($10^{15}\ \mathrm{W}$) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light $f$, and even the range of $f$ is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that $f$ exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials