14,654 research outputs found
The distribution of free electrons in the inner galaxy from pulsar dispersion measures
The dispersion measures of a sample of 149 pulsars in the inner Galaxy (absolute value of l 50 deg) were statistically analyzed to deduce the large-scale distribution of free thermal electrons in this region. The dispersion measure distribution of these pulsars shows significant evidence for a decrease in the electron scale height from a local value greater than the pulsar scale height to a value less than the pulsar scale height at galactocentric radii inside of approximately 7 kpc. An increase in the electron density (to a value around .15/cu cm at 4 to 5 kpc) must accompany such a decrease in scale height. There is also evidence for a large-scale warp in the electron distribution below the b + 0 deg plane inside the Solar circle. A model is proposed for the electron distribution which incorporates these features and Monte Carlo generated dispersion measure distributions are presented for parameters which best reproduce the observed pulsar distributions
Cheapside: commerce and commemoration
The broad street of Cheapside, Vanessa Harding shows, was a central location in the lives and minds of early modern Londoners. In a crowded city it was a significant open space where public events could be staged and important issues communicated to a wide audience. The everyday reality of shop and market trading â where qualities and values were scrutinized and false dealing punished - enhanced its association with truth and patency. Normally dominated by the authorities, it was on occasion captured by oppositional groups, though their activities tended to reinforce Cheapside's identity as a place of publicity and validation
The Deterrent Effect of Death Penalty Eligibility: Evidence from the Adoption of Child Murder Eligibility Factors
We draw on within-state variations in the reach of capital punishment statutes between 1977 and 2004 to identify the deterrent effects associated with capital eligibility. Focusing on the most prevalent eligibility expansion, we estimate that the adoption of a child murder factor is associated with an approximately 20% reduction in the homicide rate of youth victims. Eligibility expansions may enhance deterrence by (1) paving the way for more executions and (2) providing prosecutors with greater leverage to secure enhanced non-capital sentences. While executions themselves are rare, this latter channel is likely to be triggered fairly regularly, providing a reasonable basis for a general deterrent response
Attachment preference in auditory German sentences: Individual differences and pragmatic strategy
Relative clauses modify a preceding element, but as this element can be flexibly located, the point of attachment is sometimes ambiguous. Preference for this attachment can vary within languages such as German, yet explanations for differences in attachment preference related to cognitive strategies or constraints have been conflicting in the current literature. The present study aimed to assess the preference for relative clause attachment among German listeners and whether these preferences could be explained by strategy or individual differences in working memory or musical rhythm ability. We performed a sentence completion experiment, conducted post hoc interviews, and measured working memory and rhythm abilities with diagnostic tests. German listeners had no homogeneous attachment preference, although participants consistently completed individual sentences across trials according to the general preference that they reported offline. Differences in attachment preference were moreover not linked to individual differences in either working memory or musical rhythm ability. However, the pragmatic content of individual sentences sometimes overrode the general syntactic preference in participants with lower rhythm ability. Our study makes an important contribution to the field of psycholinguistics by validating offline self-reports as a reliable diagnostic for an individualâs online relative clause attachment preference. The link between pragmatic strategy and rhythm ability is an interesting direction for future research
The Effect of Statutory Rape Laws on Teen Birth Rates
Policymakers have often been explicit in expanding statutory rape laws to reduce teenage pregnancies and live births by teenage mothers, often with the goal of reducing associated welfare outlays. In this paper, we explore whether expansions in such laws are indeed associated with reductions in teen birth rates. In order to codify statutory-rape-law expansions, we use a national micro-level sample of sexual encounters to simulate the degree to which such encounters generally implicate the relevant laws. By codifying statutory-rape laws in terms of their potential reach into sexual encounters, as opposed to using crude binary treatment variables, this simulation approach facilitates the use of multi-state difference-in-difference designs in the face of highly heterogeneous legal structures. Our results suggest that live birth rates for teenage mothers fall by roughly 4.5 percent (or 0.1 percentage points) upon a 1 standard-deviation increase in the share of sexual activity among a given age group that triggers a felony for the elder party to the encounter. This response, however, is highly heterogeneous across ages and weakens notably in the case of the older teen years. Furthermore, we do not find strong results suggesting a further decline in birth rates upon increases in punishment severities
Coâoperative crossâplatform courseware development
The UKMCC (UK Mathematics Courseware Consortium) is a Consortium funded under TLTP (Training and Learning Technology Programme) to produce courseware for service mathematics teaching, using the SEFI (SociĂ©tĂ© EuropĂ©enne pour la Formation des IngĂ©nieurs) syllabus. There are agreed courseware design guidelines and a simple courseware management system which allows crossâreferencing. Courseware is divided into modules, with an author as implementer for each. On any one hardware platform, a variety of authoring languages is possible. Across hardware platforms, the design guidelines ensure that conversion is possible, and will preserve look and feel. We argue here that these arrangements provide a basis for continued coâoperation between authors and future development as the technology changes
Population Synthesis of Normal Radio and Gamma-ray Pulsars Using Markov Chain Monte Carlo Techniques
We present preliminary results of a pulsar population synthesis of normal
pulsars from the Galactic disk using a Markov Chain Monte Carlo method to
better understand the parameter space of the assumed model. We use the Kuiper
test, similar to the Kolmogorov-Smirnov test, to compare the cumulative
distributions of chosen observables of detected radio pulsars with those
simulated for various parameters. Our code simulates pulsars at birth using
Monte Carlo techniques and evolves them to the present assuming initial
spatial, kick velocity, magnetic field, and period distributions. Pulsars are
spun down to the present, given radio and gamma-ray emission characteristics,
filtered through ten selected radio surveys, and a {\it Fermi} all-sky
threshold map. Each chain begins with a different random seed and searches a
ten-dimensional parameter space for regions of high probability for a total of
one thousand different simulations before ending. The code investigates both
the "large world" as well as the "small world" of the parameter space. We apply
the K-means clustering algorithm to verify if the chains reveal a single or
multiple regions of significance. The outcome of the combined set of chains is
the weighted average and deviation of each of the ten parameters describing the
model. While the model reproduces reasonably well the detected distributions of
normal radio pulsars, it does not replicate the predicted detected
distribution of {\it Fermi} pulsars. The simulations do not produce sufficient
numbers of young, high- pulsars in the Galactic plane.Comment: 4 pages, 2 figures, The proceedings from the Pulsar Conference:
Electromagnetic Radiation from Pulsars and Magnetars will be published in the
Astronomical Society of the Pacific Conference Serie
Global Entrepreneurship Monitor United Kingdom: 2007 Executive Report
This monitoring report compares Global Entrepreneurship Monitor (GEM) measures of entrepreneurial activity in the UK with participating G7 countries and the large industrialised or industrialising countries of Brazil, Russia, India and China ("BRIC"). It also summarises entrepreneurial activity within Government Office Regions of the UK
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