An optimised scalable synthesis of H2O@C60and a new synthesis of H2@C60

New high-yielding synthetic routes to the small-molecule endofullerenes H2O@C60, D2O@C60 and H2@C60 are described. The use of high temperatures and pressures for the endohedral molecule incorporation are avoided. A new partial closure step using PPh3, and final suturing using a novel Diels–Alder/retro-Diels–Alder sequence are amongst the advances reported

Rotten Apples: An Investigation of the Prevalence and Predictors of Teacher Cheating

We develop an algorithm for detecting teacher cheating that combines information on unexpected test score fluctuations and suspicious patterns of answers for students in a classroom. Using data from the Chicago Public Schools, we estimate that serious cases of teacher or administrator cheating on standardized tests occur in a minimum of 4-5 percent of elementary school classrooms annually. Moreover, the observed frequency of cheating appears to respond strongly to relatively minor changes in incentives. Our results highlight the fact that incentive systems, especially those with bright line rules, often induce behavioral distortions such as cheating. Statistical analysis, however, may provide a means of detecting illicit acts, despite the best attempts of perpetrators to keep them clandestine.

Catching Cheating Teachers: The Results of an Unusual Experiment in Implementing Theory

This paper reports on the results of a prospective implementation of methods for detecting teacher cheating. In Spring 2002, over 100 Chicago Public Schools elementary classrooms were selected for retesting based on the cheating detection algorithm. Classrooms prospectively identified as likely cheaters experienced large test score declines. In contrast, classes that had large test score gains on the original test, but were prospectively identified as being unlikely to have cheated, maintained their original gains. Randomly selected classrooms also maintained their gains. The cheating detection tools were thus demonstrated to be effective in distinguishing between classrooms that achieved large test-score gains as a consequence of cheating versus those whose gains were the result of outstanding teaching. In addition, the data generated by the implementation experiment highlight numerous ways in which the original cheating detection methods can be improved in the future.

Security Policy Specification Using a Graphical Approach

A security policy states the acceptable actions of an information system, as the actions bear on security. There is a pressing need for organizations to declare their security policies, even informal statements would be better than the current practice. But, formal policy statements are preferable to support (1) reasoning about policies, e.g., for consistency and completeness, (2) automated enforcement of the policy, e.g., using wrappers around legacy systems or after the fact with an intrusion detection system, and (3) other formal manipulation of policies, e.g., the composition of policies. We present LaSCO, the Language for Security Constraints on Objects, in which a policy consists of two parts: the domain (assumptions about the system) and the requirement (what is allowed assuming the domain is satisfied). Thus policies defined in LaSCO have the appearance of conditional access control statements. LaSCO policies are specified as expressions in logic and as directed graphs, giving a visual view of policy. LaSCO has a simple semantics in first order logic (which we provide), thus permitting policies we write, even for complex policies, to be very perspicuous. LaSCO has syntax to express many of the situations we have found to be useful on policies or, more interesting, the composition of policies. LaSCO has an object-oriented structure, permitting it to be useful to describe policies on the objects and methods of an application written in an object-oriented language, in addition to the traditional policies on operating system objects. A LaSCO specification can be automatically translated into executable code that checks an invocation of a program with respect to a policy. The implementation of LaSCO is in Java, and generates wrappers to check Java programs with respect to a policy.Comment: 28 pages, 22 figures, in color (but color is not essential for viewing); UC Davis CS department technical report (July 22, 1998

Micromechanical microphone using sideband modulation of nonlinear resonators

We report the successful detection of an audio signal via sideband modulation of a nonlinear piezoelectric micromechanical resonator. The 270$\times$96-$\mu$m resonator was shown to be reliable in audio detection for sound intensity levels as low as ambient room noise and to have an unamplified sensitivity of 23.9 $\mu$V/Pa. Such an approach may be adapted in acoustic sensors and microphones for consumer electronics or medical equipment such as hearing aids.Comment: 5 pages, 3 figure

The Effect of School Choice on Student Outcomes: Evidence from Randomized Lotteries

School choice has become an increasingly prominent strategy for urban school districts seeking to enhance academic achievement. Evaluating the impact of such programs is complicated by the fact that a highly select sample of students takes advantage of these programs. To overcome this difficulty, we exploit randomized lotteries that determine high school admission in the Chicago Public Schools. Surprisingly, we find little evidence that attending sought after programs provides any benefit on a wide variety of traditional academic measures, including standardized test scores, attendance rates, course-taking, and credit accumulation. This is true despite the fact that those students who win the lotteries attend better high schools along a number of dimensions, including higher peer achievement levels, higher peer graduation rates, and lower levels of poverty. We do, however, uncover evidence that attendance at such schools may improve a subset of non-traditional outcome measures, such as self-reported disciplinary incidences and arrest rates.

Magic composite pulses

I describe composite pulses during which the average dipolar interactions within a spin ensemble are controlled while realizing a global rotation. The construction method used is based on the average Hamiltonian theory and rely on the geometrical properties of the spin-spin dipolar interaction only. I present several such composite pulses robust against standard experimental defects in NRM: static or radio-frequency field miscalibration, fields inhomogeneities. Numerical simulations show that the magic sandwich pulse sequence, a pulse sequence that reverse the average dipolar field while applied, is plagued by defects originating from its short initial and final \pi/2 radio-frequency pulses. Using the magic composite pulses instead of \pi/2 pulses improves the magic sandwich effect. A numerical test using a classical description of NMR allows to check the validity of the magic composite pulses and estimate their efficiency.Comment: 22 pages, 6 figure

An Analysis Of Perceptions Of Restaurant Authenticity At Food Tourism Destinations In The Southeastern U.S

The purpose of this study was to develop a comprehensive scale, containing multiple restaurant attributes and authenticity conceptualizations, to measure restaurant authenticity; to test a model examining the mediators and outcomes of restaurant authenticity at independent, full service Southern-style restaurants at food tourism destinations in the Southeastern U.S.; and to determine if the influences of restaurant authenticity differ between food tourists, general tourists, and locals. A four-step approach adapted from Netemeyer et al. (2003) was used to develop the restaurant authenticity scale (RAS). Ultimately, the RAS contained six authenticity conceptualizations, 20 items and three dimensions: restaurant heritage and environment, food and beverage, and restaurant diners. A conceptual model based on social cognitive theory, Mehrabian-Russell model, congruence theory, the consumer-based model of authenticity, and associative network theory was then tested. Overall, the model contained 10 hypotheses and each was confirmed. By confirming these hypothesis, it was determined that relationships between restaurant authenticity and satisfaction and restaurant authenticity and restaurant loyalty were both partially mediated, while a relationship between restaurant authenticity and place attachment was fully mediated. Lastly, perceptions of food tourists, general tourists, and locals were compared via multigroup moderation analysis and MANOVA. Findings suggested that restaurant authenticity has the strongest influence on locals. This study contributed to both theory and practice. For theory, it determined which items, authenticity conceptualizations, and dimensions were included in the RAS. By testing the conceptual model, the efficacy of several theories and models were confirmed in the foodservice and food tourism context. Restaurant authenticity’s influence on relevant mediating and outcome variables was also confirmed. Lastly, results from the multigroup moderation analysis and MANOVA tests determined that some differences exist between the food tourists, general tourists, and locals with regard to authenticity. For restaurant practitioners, the structure of the RAS should call attention to certain restaurant attributes with regards to authenticity. Also, the multigroup moderation analysis and MANOVA tests determined that local restaurants should actively reach out to locals. For tourism practitioners, results from the conceptual model suggest that authentic local restaurants may serve as effective venues to engage tourists with certain travel promotions