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LDRD Project progress report: Broadly tunable, solid-state coherent light sources
Our program of nanosecond optical parametric oscillator (OPO) development has concentrated on improving the spectral purity and tunability as well as the beam quality of OPO`s and other tunable sources based on frequency mixing in nonlinear crystals. To facilitate quick evaluation of new OPO and frequency-mixing configurations and to provide insight to OPO operation, we developed a computer model of seeded OPO operation that includes pump depletion, birefringent walkoff, diffraction, temporal and spatial beam profiles, and cavity optics. It predicts conversion efficiency, beam quality, spectra, and time behavior. Our model development was complemented by laboratory OPO studies that served to validate the model and also to highlight the practical problems associated with limitations of optical coating and nonlinear crystal growth technologies. We present here a set of papers that compare model calculation and laboratory characterization of a seeded, nanosecond OPO, that apply the model to illustrate distortions of specta and beam quality in frequency mixing, and that point out the peculiarities of two-crystal frequency mixing
Mesoscopic QCD and the Theta Vacua
The partition function of QCD is analyzed for an arbitrary number of flavors,
N_f, and arbitrary quark masses including the contributions from all
topological sectors in the Leutwyler--Smilga regime. For given N_f and
arbitrary vacuum angle, \theta, the partition function can be reduced to N_f-2
angular integrations of single Bessel functions. For two and three flavors, the
\theta dependence of the QCD vacuum is studied in detail. For N_f= 2 and 3, the
chiral condensate decreases monotonically as \theta increases from zero to \pi
and the chiral condensate develops a cusp at \theta=\pi for degenerate quark
masses in the macroscopic limit. We find a discontinuity at \theta=\pi in the
first derivative of the energy density with respect to \theta for degenerate
quark masses. This corresponds to the first--order phase transition in which CP
is spontaneously broken, known as Dashen's phenomena.Comment: 31 pages, revtex, 10 figures, final version to appear in Nucl. Phys.
Nonpolitical Images Evoke Neural Predictors of Political Ideology
Political ideologies summarize dimensions of life that define how a person organizes their public and private behavior, including their attitudes associated with sex, family, education, and personal autonomy [1, 2]. Despite the abstract nature of such sensibilities, fundamental features of political ideology have been found to be deeply connected to basic biological mechanisms [3–7] that may serve to defend against environmental challenges like contamination and physical threat [8–12]. These results invite the provocative claim that neural responses to nonpolitical stimuli (like contaminated food or physical threats) should be highly predictive of abstract political opinions (like attitudes toward gun control and abortion) [13]. We applied a machinelearning method to fMRI data to test the hypotheses that brain responses to emotionally evocative images predict individual scores on a standard political ideology assay. Disgusting images, especially those related to animalreminder disgust (e.g., mutilated body), generate neural responses that are highly predictive of political orientation even though these neural predictors do not agree with participants’ conscious rating of the stimuli. Images from other affective categories do not support such predictions. Remarkably, brain responses to a single disgusting stimulus were sufficient to make accurate predictions about an individual subject’s political ideology. These results provide strong support for the idea that fundamental neural processing differences that emerge under the challenge of emotionally evocative stimuli may serve to structure political beliefs in ways formerly unappreciated
Continuous-wave room-temperature diamond maser
The maser, older sibling of the laser, has been confined to relative
obscurity due to its reliance on cryogenic refrigeration and high-vacuum
systems. Despite this it has found application in deep-space communications and
radio astronomy due to its unparalleled performance as a low-noise amplifier
and oscillator. The recent demonstration of a room-temperature solid- state
maser exploiting photo-excited triplet states in organic pentacene molecules
paves the way for a new class of maser that could find applications in
medicine, security and sensing, taking advantage of its sensitivity and low
noise. However, to date, only pulsed operation has been observed in this
system. Furthermore, organic maser molecules have poor thermal and mechanical
properties, and their triplet sub-level decay rates make continuous emission
challenging: alternative materials are therefore required. Therefore, inorganic
materials containing spin-defects such as diamond and silicon carbide have been
proposed. Here we report a continuous-wave (CW) room-temperature maser
oscillator using optically pumped charged nitrogen-vacancy (NV) defect centres
in diamond. This demonstration unlocks the potential of room-temperature
solid-state masers for use in a new generation of microwave devices.Comment: 7 pages, 4 figure
Gangs and guilt: Towards a new theory of horror film
The most basic and unanimous statement made in scholarship on horror films is that horror films are ‘about’ fear: the primary purpose of horror films is to scare viewers. Based on horror films from the 1970s until the present in which child gangs play a significant part, this essay advances a new theory of horror film, namely that horror films primarily seek to elicit not fear but guilt. The analysis focuses on four topics: themes, camera angles, horror’s cinematic casting of ‘abnormality,’ and the rift, unique to the horror genre, between audience ‘alignment’ and ‘allegiance.
Bremsstrahlung in the gravitational field of a cosmic string
In the framework of QED we investigate the bremsstrahlung process for an
electron passing by a straight static cosmic string. This process is precluded
in empty Minkowski space-time by energy and momentum conservation laws. It
happens in the presence of the cosmic string as a consequence of the conical
structure of space, in spite of the flatness of the metric. The cross section
and emitted electromagnetic energy are computed and analytic expressions are
found for different energies of the incoming electron. The energy interval is
divided in three parts depending on whether the energy is just above electron
rest mass , much larger than , or exceeds , with the
string mass per unit length in Planck units. We compare our results with those
of scalar QED and classical electrodynamics and also with conic pair production
process computed earlier.Comment: 21 pages, to appear in Phys. Rev. D., KONS-RGKU-94-0
Report of Third Annual Seminar on Estate Planning
Reports from the UK/CLE Third Annual Seminar on Estate Planning held July 23-24, 1976
The PHENIX Experiment at RHIC
The physics emphases of the PHENIX collaboration and the design and current
status of the PHENIX detector are discussed. The plan of the collaboration for
making the most effective use of the available luminosity in the first years of
RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program
available at http://www.rhic.bnl.gov/phenix
The utilisation of health research in policy-making: Concepts, examples and methods of assessment
The importance of health research utilisation in policy-making, and of understanding the
mechanisms involved, is increasingly recognised. Recent reports calling for more resources to
improve health in developing countries, and global pressures for accountability, draw greater
attention to research-informed policy-making. Key utilisation issues have been described for at
least twenty years, but the growing focus on health research systems creates additional dimensions.
The utilisation of health research in policy-making should contribute to policies that may eventually
lead to desired outcomes, including health gains. In this article, exploration of these issues is
combined with a review of various forms of policy-making. When this is linked to analysis of
different types of health research, it assists in building a comprehensive account of the diverse
meanings of research utilisation.
Previous studies report methods and conceptual frameworks that have been applied, if with varying
degrees of success, to record utilisation in policy-making. These studies reveal various examples of
research impact within a general picture of underutilisation.
Factors potentially enhancing utilisation can be identified by exploration of: priority setting;
activities of the health research system at the interface between research and policy-making; and
the role of the recipients, or 'receptors', of health research. An interfaces and receptors model
provides a framework for analysis.
Recommendations about possible methods for assessing health research utilisation follow
identification of the purposes of such assessments. Our conclusion is that research utilisation can
be better understood, and enhanced, by developing assessment methods informed by conceptual
analysis and review of previous studies
Public value and political astuteness in the work of public managers: the art of the possible
The public value framework, with its call for more entrepreneurial activities by public managers, has attracted concern and criticism about its implicit breaching of the politics/administration dichotomy. This paper explores the role of political astuteness not only in discerning and creating public value, but also in enabling public managers to be sensitive to the dichotomy. We employ a conceptual framework to identify the skills of political astuteness, and then articulate these in relation to identifying and generating public value. Drawing on a survey of 1012 public managers in Australia, New Zealand and the UK, and depth interviews with 42 of them, we examine the perceptions and capabilities of public managers in producing value for the public while traversing the line (or zone) between politics and administration. We conclude that political astuteness is essential to both creating value and maintaining allegiance to democratic principles
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