Encouraging Social Innovation Through Capital: Using Technology to Address Barriers

Outlines how technology can help foster a robust capital market for public education innovation by improving content, linking technology with face-to-face networks, and streamlining transactions. Suggests steps for government, foundations, and developers

Strategies for Reducing the Impact of Tumour Motion During Helical Tomotherapy

Tumour motion presents a significant limitation for effective radiotherapy of lung cancer, and more specifically for helical tomotherapy. The simultaneous and continuous movements of tomotherapy subsystems (gantry, couch, and binary multi-leaf collimator) can lead to inaccurate dose delivery, when combined with tumour motion. In this thesis, we have investigated the impact of tumour motion and strategies to reduce the resulting dose discrepancies for helical tomotherapy, through computer simulations and film measurements performed in a dynamic body phantom. Three distinctively different types of dose discrepancies have been isolated: dose rounding, dose rippling, and the intensity-modulated radiation therapy (IMRT) asynchronization effect. Each effect was shown to be affected by different combinations of tumour motion and treatment parameters. In clinical practice using a conventional fractionation scheme, the dose rounding effect remains the major concern, which can be compensated by assigning a larger treatment margin around the tumour volume. For hypofractionation schemes, the IMRT asynchronization effect can become an additional concern by introducing dose discrepancies inside the target volume, necessitating the use of a motion management technique. Two new motion management techniques have thus been developed for helical tomotherapy: loose helical tomotherapy with breath-holding and multi-pass respiratory gating. Both methods require the treatment couch to be reset to its starting position to repeat the entire helical treatment, until nearly all planned dose is delivered. For sinusoidal target motion, employing multi-pass respiratory gating was shown to reduce the dose deviation inside the target volume from 14% to 2% for a single fraction, using 4 gated passes. For non-sinusoidal tumour motion causing a dose deviation of 6% within the tumour volume, the required number of passes to keep the dose deviation below 1% was approximately 4 passes for 30 fractions and 5 passes for 3 fractions, demonstrating the feasibility of the multi-pass respiratory gating approach. Clinical implementation of the multi-pass respiratory gating technique would require a number of electronic control and communication modifications to the existing tomotherapy machine, which would lead to significant improvements in the dose distributions delivered for lung tomotherapy treatments – especially for patients exhibiting large tumour motion who are treated with hypofractionation schemes

A Markov Switching Model of Congressional Partisan Regimes

Studies of development and change in partisan fortunes in the US emphasize epochs of partisan stability, separated by critical events or turning points. A major empirical issue that has plagued the study of American political development is the estimation of the critical moments and durations of these partisan regimes. In this paper we introduce a fresh approach to the study of partisan regimes. Our method is based in the method of Markov switching, introduced by James Hamilton. We apply Hamilton’s approach to the size of party coalitions in the US House of Representatives from 1854 to the present. Our model assumes that the political system is either in a state of domination by one party or it is not (in which case the other party dominates). The Markov switching approach also yields estimated state probabilities that allow us to make inferences about periods of empirical party balance. Roughly speaking, when the Republicans constitute the dominant partisan coalition, they can expect to capture 60 percent of House seats in any given election. The Democrats can expect 59 percent when dominant. Our method also allows the estimation of critical transition points between Republican and Democratic partisan coalitions. The periods we identify as governed by a being Republican coalition are roughly 1860 through 1872, 1894 through 1906, and 1918 through 1928.

Fiction, Culture and Pedophilia: Fantasy and the First Amendment after United States v. Whorley

In 1998, congressional and public sentiment was set ablaze by the publication of a seemingly esoteric academic article by three previously little-known psychologists. The article, in an American Psychological Association ("APA") journal, Psychological Bulletin, challenged the "lay belie[f] that child sexual abuse (CSA) causes intense harm" and concluded that the common construct of child sexual abuse was "of questionable scientific validity." The authors suggested further that psychologists researching child sexuality use different terms, "adultchild sex, a value-neutral term" for "a willing encounter with positive reactions," reserving "child sexual abuse, a term that implies harm to the individual," for a nonconsensual experience accompanied by negative feelings. The National Association for Research and Therapy of Homosexuality ("NARTH"), a group that claims to "help" gays and lesbians rid themselves of "unwanted homosexuality," was the first to comment. NARTH claimed that the APA was attempting to "normalize pedophiles." Dr. Laura Schlessinger agreed, and together with NARTH and the conservative organization Family Research Council, prodded Congress to respond. House Majority Whip Tom DeLay (R-Texas) and Dr. Schlessinger appeared at a press conference convened by the Family Research Council, introducing a bill requiring the APA to renounce the findings of the study. A House Resolution condemning the psychologists' conclusions passed 355 to zero in 1999.8 Looking back on the episode, literary critic Kathryn Bond Stockton comments that "Congress, it would seem, has acted only once to resolve against science: in order to say that children must be harmed.

Evaluating the Correlation Characteristics of Arbitrary AM and FM Radio Signals for the Purpose of Navigation

The Global Positioning System (GPS) provides position estimates on the Earth at anytime, anywhere and in any weather. However, to provide robust positioning, GPS requires an unobstructed path to satellite signals. As such, GPS performance generally degrades or becomes non-existent in environments such as large urban areas. This research investigates and analyzes the correlation characteristics of arbitrary AM and FM radio signals for the purpose of navigation. Simulations are conducted with different combinations of correlation methods (`fixed\u27 or `varying\u27), modulation types (AM or FM), and signal types (song or voice). Out of the eight different variations considered, only two provided promising results for the purpose of navigation. Both the FM voice and FM song signals exhibit distinct autocorrelation peaks (i.e., 5.0 dB peak-to-sidelobe ratios) using the `fixed\u27 reference correlation method. However, results for both FM signal types revealed limited potential for navigation when using the `varying\u27 reference correlation method. All the AM signals considered yielded relatively limited potential for navigation using either correlation method

On Determining Minimal Spectrally Arbitrary Patterns

In this paper we present a new family of minimal spectrally arbitrary patterns which allow for arbitrary spectrum by using the Nilpotent-Jacobian method. The novel approach here is that we use the Intermediate Value Theorem to avoid finding an explicit nilpotent realization of the new minimal spectrally arbitrary patterns.Comment: 8 page