The Cleo III Ring Imaging Cherenkov Detector

The CLEO detector has been upgraded to include a state of the art particle identification system, based on the Ring Imaging Cherenkov Detector (RICH) technology, in order to take data at the upgraded CESR electron positron collider. The expected performance is reviewed, as well as the preliminary results from an engineering run during the first few months of operation of the CLEO III detector.Comment: 5 pages, 2 Figures Talk given by M. Artuso at 8th Pisa Meeting on Advanced Detectors, May 200

Dynamic structure factors of a dense mixture

We compute the dynamic structure factors of a dense binary liquid mixture. These describe dynamics on molecular length scales, where structural relaxation is important. We find that the presence of a few large particles in a dense fluid of small particles slows down the dynamics considerably. We also observe a deep narrowing of the spectrum for a disordered mixture composed of a nearly equal packing of the two species. In contrast, a few small particles diffuse easily in the background of a dense fluid of large particles. We expect our results to describe neutron scattering from a dense mixture

Searching for Earth analogues around the nearest stars: the disk age-metallicity relation and the age distribution in the Solar Neighbourhood

The chemical composition of Earth's atmosphere has undergone substantial evolution over the course of its history. It is possible, even likely, that terrestrial planets in other planetary systems have undergone similar changes; consequently, the age distribution of nearby stars is an important consideration in designing surveys for Earth-analogues. Valenti & Fischer (2005) provide age and metallicity estimates for 1039 FGK dwarfs in the Solar Neighbourhood. Using the Hipparcos catalogue as a reference to calibrate potential biases, we have extracted volume-limited samples of nearby stars from the Valenti-Fischer dataset. Unlike other recent investigations, our analysis shows clear evidence for an age-metallicity relation in the local disk, albeit with substantial dispersion at any epoch. The mean metallicity increases from -0.3 dex at a lookback time of ~10 Gyrs to +0.15 dex at the present day. Supplementing the Valenti-Fischer measurements with literature data to give a complete volume-limited sample, the age distribution of nearby FGK dwarfs is broadly consistent with a uniform star-formation rate over the history of the Galactic disk. In striking contrast, most stars known to have planetary companions are younger than 5 Gyrs; however, stars with planetary companions within 0.4 AU have a significantly flatter age distribution, indicating that those systems are stable on timescales of many Gyrs. Several of the older, lower metallicity host stars have enhanced [alpha/Fe] ratios, implying membership of the thick disk. If the frequency of terrestrial planets is also correlated with stellar metallicity, then the median age of such planetary system is likely to be ~3 Gyrs. We discuss the implications of this hypothesis in designing searches for Earth analogues among the nearby stars.Comment: Accepted for publication in Ap

The CLEO-III Ring Imaging Cherenkov Detector

The CLEO-III Detector upgrade for charged particle identification is discussed. The RICH design uses solid LiF crystal radiators coupled with multi-wire chamber photon detectors, using TEA as the photosensor, and low-noise Viking readout electronics. Results from our beam test at Fermilab are presented.Comment: Invited talk by R.J. Mountain at ``The 3rd International Workshop on Ring Imaging Cherenkov Detectors," a research workshop of the Israel Science Foundation, Ein-Gedi, Dead-Sea, Israel, Nov. 15-20, 1998, 14 pages, 9 figure

Light scattering spectra of supercooled molecular liquids

The light scattering spectra of molecular liquids are derived within a generalized hydrodynamics. The wave vector and scattering angle dependences are given in the most general case and the change of the spectral features from liquid to solidlike is discussed without phenomenological model assumptions for (general) dielectric systems without long-ranged order. Exact microscopic expressions are derived for the frequency-dependent transport kernels, generalized thermodynamic derivatives and the background spectra.Comment: 12 page

Growing Correlation Length on Cooling Below the Onset of Caging in a Simulated Glass-Forming Liquid

We present a calculation of a fourth-order, time-dependent density correlation function that measures higher-order spatiotemporall correlations of the density of a liquid. From molecular dynamics simulations of a glass-forming Lennard-Jones liquid, we find that the characteristic length scale of this function has a maximum as a function of time which increases steadily beyond the characteristic length of the static pair correlation function $g(r)$ in the temperature range approaching the mode coupling temperature from above

Cenozoic Global Sea Level, Sequences, and the New Jersey Transect: Results from Coastal Plain and Continental Slope Drilling

The New Jersey Sea Level Transect was designed to evaluate the relationships among global sea level (eustatic) change, unconformity-bounded sequences, and variations in subsidence, sediment supply, and climate on a passive continental margin. By sampling and dating Cenozoic strata from coastal plain and continental slope locations, we show that sequence boundaries correlate (within ±0.5 myr) regionally (onshore-offshore) and interregionally (New Jersey-Alabama-Bahamas), implicating a global cause. Sequence boundaries correlate with δ18O increases for at least the past 42 myr, consistent with an ice volume (glacioeustatic) control, although a causal relationship is not required because of uncertainties in ages and correlations. Evidence for a causal connection is provided by preliminary Miocene data from slope Site 904 that directly link δ18O increases with sequence boundaries. We conclude that variation in the size of ice sheets has been a primary control on the formation of sequence boundaries since ∼42 Ma. We speculate that prior to this, the growth and decay of small ice sheets caused small-amplitude sea level changes (less than 20 m) in this supposedly ice-free world because Eocene sequence boundaries also appear to correlate with minor δ18O increases. Subsidence estimates (backstripping) indicate amplitudes of short-term (million-year scale) lowerings that are consistent with estimates derived from δ18O studies (25–50 m in the Oligocene-middle Miocene and 10–20 m in the Eocene) and a long-term lowering of 150–200 m over the past 65 myr, consistent with estimates derived from volume changes on mid-ocean ridges. Although our results are consistent with the general number and timing of Paleocene to middle Miocene sequences published by workers at Exxon Production Research Company, our estimates of sea level amplitudes are substantially lower than theirs. Lithofacies patterns within sequences follow repetitive, predictable patterns: (1) coastal plain sequences consist of basal transgressive sands overlain by regressive highstand silts and quartz sands; and (2) although slope lithofacies variations are subdued, reworked sediments constitute lowstand deposits, causing the strongest, most extensive seismic reflections. Despite a primary eustatic control on sequence boundaries, New Jersey sequences were also influenced by changes in tectonics, sediment supply, and climate. During the early to middle Eocene, low siliciclastic and high pelagic input associated with warm climates resulted in widespread carbonate deposition and thin sequences. Late middle Eocene and earliest Oligocene cooling events curtailed carbonate deposition in the coastal plain and slope, respectively, resulting in a switch to siliciclastic sedimentation. In onshore areas, Oligocene sequences are thin owing to low siliciclastic and pelagic input, and their distribution is patchy, reflecting migration or progradation of depocenters; in contrast, Miocene onshore sequences are thicker, reflecting increased sediment supply, and they are more complete downdip owing to simple tectonics. We conclude that the New Jersey margin provides a natural laboratory for unraveling complex interactions of eustasy, tectonics, changes in sediment supply, and climate change

A critical analysis of the potential for EU Common Agricultural Policy measures to support wild pollinators on farmland

1. Agricultural intensification and associated loss of high‐quality habitats are key drivers of insect pollinator declines. With the aim of decreasing the environmental impact of agriculture, the 2014 EU Common Agricultural Policy (CAP) defined a set of habitat and landscape features (Ecological Focus Areas: EFAs) farmers could select from as a requirement to receive basic farm payments. To inform the post‐2020 CAP, we performed a European‐scale evaluation to determine how different EFA options vary in their potential to support insect pollinators under standard and pollinator‐friendly management, as well as the extent of farmer uptake. 2. A structured Delphi elicitation process engaged 22 experts from 18 European countries to evaluate EFAs options. By considering life cycle requirements of key pollinating taxa (i.e. bumble bees, solitary bees and hoverflies), each option was evaluated for its potential to provide forage, bee nesting sites and hoverfly larval resources. 3. EFA options varied substantially in the resources they were perceived to provide and their effectiveness varied geographically and temporally. For example, field margins provide relatively good forage throughout the season in Southern and Eastern Europe but lacked early‐season forage in Northern and Western Europe. Under standard management, no single EFA option achieved high scores across resource categories and a scarcity of late season forage was perceived. 4. Experts identified substantial opportunities to improve habitat quality by adopting pollinator‐friendly management. Improving management alone was, however, unlikely to ensure that all pollinator resource requirements were met. Our analyses suggest that a combination of poor management, differences in the inherent pollinator habitat quality and uptake bias towards catch crops and nitrogen‐fixing crops severely limit the potential of EFAs to support pollinators in European agricultural landscapes. 5. Policy Implications. To conserve pollinators and help protect pollination services, our expert elicitation highlights the need to create a variety of interconnected, well‐managed habitats that complement each other in the resources they offer. To achieve this the Common Agricultural Policy post‐2020 should take a holistic view to implementation that integrates the different delivery vehicles aimed at protecting biodiversity (e.g. enhanced conditionality, eco‐schemes and agri‐environment and climate measures). To improve habitat quality we recommend an effective monitoring framework with target‐orientated indicators and to facilitate the spatial targeting of options collaboration between land managers should be incentivised