The time resolved measurement of ultrashort THz-band electric fields without an ultrashort probe

The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe and self-referenced FROG makes the technique inherently immune to timing jitter between the optical probe and THz pulse, and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.Comment: 7 pages, 3 figures, submitted to AP

High Resolution CO and H2 Molecular Line Imaging of a Cometary Globule in the Helix Nebula

We report high resolution imaging of a prominent cometary globule in the Helix nebula in the CO J=1-0 (2.6 mm) and H2 v=1-0 S(1) (2.12 micron) lines. The observations confirm that globules consist of dense condensations of molecular gas embedded in the ionized nebula. The head of the globule is seen as a peak in the CO emission with an extremely narrow line width (0.5 km/s) and is outlined by a limb-brightened surface of H2 emission facing the central star and lying within the photo-ionized halo. The emission from both molecular species extends into the tail region. The presence of this extended molecular emission provides new constraints on the structure of the tails, and on the origin and evolution of the globules.Comment: 12 pages, 3 figures. To appear in The Astrophysical Journal Letter

My Imagination Versus Your Feelings: Can Personal Affective Forecasts Be Improved by Knowing Other Peoples' Emotions?

A proposed remedy for biased affective forecasts is to base judgments on the actual feelings of people (surrogates) currently experiencing the event, rather than using imagination which conjures an inaccurate vision of the future. Gilbert et al. (2009) forced people to use surrogate reports by withholding all event information, resulting in better predictions. However, in life surrogate information rarely supplants event information - can people effectively integrate both types of information into their judgments? In 5 studies, respondents predicted the impact of a health state on their own happiness. Respondents incorporated surrogate information into their judgments both in the presence and absence of event information. However, they inappropriately discounted other people’s experiences as a valid predictor of their own - particularly in the presence of event information – and imagined their happiness would be different to surrogates’ happiness. Excluding pre-existing event knowledge, changing the size of the surrogate sample, or increasing the size of the response scale, did not alter the adjustment. Although surrogate information improved affective forecasts, its influence was diminished by the presence of event information

Decentralized Supply Chain Formation: A Market Protocol and Competitive Equilibrium Analysis

Supply chain formation is the process of determining the structure and terms of exchange relationships to enable a multilevel, multiagent production activity. We present a simple model of supply chains, highlighting two characteristic features: hierarchical subtask decomposition, and resource contention. To decentralize the formation process, we introduce a market price system over the resources produced along the chain. In a competitive equilibrium for this system, agents choose locally optimal allocations with respect to prices, and outcomes are optimal overall. To determine prices, we define a market protocol based on distributed, progressive auctions, and myopic, non-strategic agent bidding policies. In the presence of resource contention, this protocol produces better solutions than the greedy protocols common in the artificial intelligence and multiagent systems literature. The protocol often converges to high-value supply chains, and when competitive equilibria exist, typically to approximate competitive equilibria. However, complementarities in agent production technologies can cause the protocol to wastefully allocate inputs to agents that do not produce their outputs. A subsequent decommitment phase recovers a significant fraction of the lost surplus

Urban Catholic Elementary Schools: What are the Governance Models?

The closure of nearly half of Catholic elementary schools in the United States since the 1960s has led to the development of many innovative initiatives to stabilize, strengthen, and sustain urban Catholic elementary education. Improving school governance models has been a common agenda of these efforts. This study examined the governance models in use by urban Catholic elementary schools across the United States. Seven major governance models for urban Catholic elementary schools were identified and studied using structured interviews and document analysis. An eighth model, faith-inspired charter schools, is presented as one alternative to a Catholic school. The variety of governance models demonstrates innovation in response to the plight of urban Catholic elementary schools across the country. Common trends across the models are discussed. In short, traditional governance approaches are giving way to more strategic, data-supported models that have the potential t

The Compositional Structure of the Asteroid Belt

The past decade has brought major improvements in large-scale asteroid discovery and characterization with over half a million known asteroids and over 100,000 with some measurement of physical characterization. This explosion of data has allowed us to create a new global picture of the Main Asteroid Belt. Put in context with meteorite measurements and dynamical models, a new and more complete picture of Solar System evolution has emerged. The question has changed from "What was the original compositional gradient of the Asteroid Belt?" to "What was the original compositional gradient of small bodies across the entire Solar System?" No longer is the leading theory that two belts of planetesimals are primordial, but instead those belts were formed and sculpted through evolutionary processes after Solar System formation. This article reviews the advancements on the fronts of asteroid compositional characterization, meteorite measurements, and dynamical theories in the context of the heliocentric distribution of asteroid compositions seen in the Main Belt today. This chapter also reviews the major outstanding questions relating to asteroid compositions and distributions and summarizes the progress and current state of understanding of these questions to form the big picture of the formation and evolution of asteroids in the Main Belt. Finally, we briefly review the relevance of asteroids and their compositions in their greater context within our Solar System and beyond.Comment: Accepted chapter in Asteroids IV in the Space Science Series to be published Fall 201

The 2s atomic level in muonic 208-Pb

Relative intensities and energy measurements of 2s level in muonic Pb-20