Observation of blue-shifted ultralong-range Cs2_{2} Rydberg molecules

We observe ultralong-range blue-shifted Cs$_{2}$ molecular states near $ns_{1/2}$ Rydberg states in an optical dipole trap, where $31\leq n\leq34$. The accidental near degeneracy of $(n-4)l$ and $ns$ Rydberg states for $l>2$ in Cs, due to the small fractional $ns$ quantum defect, leads to non-adiabatic coupling among these states, producing potential wells above the $ns$ thresholds. Two important consequences of admixing high angular momentum states with $ns$ states are the formation of large permanent dipole moments, $\sim 15-100\,$Debye, and accessibility of these states via two-photon association. The observed states are in excellent agreement with theory. Both projections of the total angular momentum on the internuclear axis are visible in the experiment

Safety, the Preface Paradox and Possible Worlds Semantics

This paper contains an argument to the effect that possible worlds semantics renders semantic knowledge impossible, no matter what ontological interpretation is given to possible worlds. The essential contention made is that possible worlds semantic knowledge is unsafe and this is shown by a parallel with the preface paradox

Photoionization Rates of Cs Rydberg Atoms in a 1064 nm Far Off-Resonance Trap

Experimental measurements of photoionization rates of $nD_{5/2}$ Rydberg states of Cs ($50 \leq n \leq 75$) in a 1064 nm far off-resonance dipole trap are presented. The photoionization rates are obtained by measuring the lifetimes of Rydberg atoms produced inside of a 1064 nm far off-resonance trap and comparing the lifetimes to corresponding control experiments in a magneto-optical trap. Experimental results for the control experiments agree with recent theoretical predictions for Rydberg state lifetimes and measured photoionization rates are in agreement with transition rates calculated from a model potential.Comment: 12 pages, 4 figure

ENVIROSAT-2000 report: Federal agency satellite requirements

The requirement of Federal agencies, other than NOAA, for the data and services of civil operational environmental satellites (both polar orbiting and geostationary) are summarized. Agency plans for taking advantage of proposed future Earth sensing space systems, domestic and foreign, are cited also. Current data uses and future requirements are addressed as identified by each agency

Irreversibility and Polymer Adsorption

Physisorption or chemisorption from dilute polymer solutions often entails irreversible polymer-surface bonding. We present a theory of the non-equilibrium layers which result. While the density profile and loop distribution are the same as for equilibrium layers, the final layer comprises a tightly bound inner part plus an outer part whose chains make only fN surface contacts where N is chain length. The contact fractions f follow a broad distribution, P(f) ~ f^{-4/5}, in rather close agreement with strong physisorption experiments [H. M. Schneider et al, Langmuir v.12, p.994 (1996)].Comment: 4 pages, submitted to Phys. Rev. Let

Market-Oriented Strategies to Improve Household Access to Food: Experience from Sub-Saharan Africa

The objectives of this report are to identify market-oriented strategies to alleviate both chronic and transitory food insecurity, and to examine the interactions between short-run targeting mechanisms and longer-run strategies designed to alleviate the chronic causes of inadequate access to food. The main premise of the report is that sustained improvements in household access to food in Sub-Saharan Africa require the development of more reliable food and input markets that (a) create incentives to adopt cost-reducing investments at various stages in the food system; and (b) offer incentives for rural households to shift from a subsistence-oriented pattern of production and consumption to more productive systems based on specialization and gains from exchange. Sustained productivity growth in most parts of the world has typically entailed some form of structural transformation, which, in the historical development processes of other regions, has been a prerequisite for broad-based and sustained growth in productivity, real incomes and purchasing power throughout society. Structural transformation involves a movement away from subsistence-oriented, household-level production toward an integrated economy based on specialization and exchange. But specialization makes households dependent on the performance of exchange systems. The ability to capture the productivity gains from new technology and specialization thus depends on reducing the risks and uncertainty of market-based exchange, thereby facilitating greater participation in the types of specialized production and consumption patterns involved in the process of structural transformation. Section 3 presents empirical evidence from research conducted in Africa to draw conclusions about how the design of agricultural policies and transfer programs have affected household access to food in both rural and urban areas. Based on the foregoing, section 4 presents the following guidelines for the design of strategies to promote access to food in Africa: (1.) Focus on achieving productivity gains in the food system. (2.) Focus on how food and income transfer programs can be designed to promote the long-run development of the food system- the basis for providing food for most people over the long run in addition to providing food to people in the short run. (3.) Focus on reducing consumer food costs by expanding the range of products available to produce and consume. (4.) Focus on the cost and reliability of food supplies to rural areas as a component of non-farm, livestock, and other income diversification strategies designed to promote access to food over the longer run. (5.) Focus on developing local analytical expertise to help guide food system development.Food Security and Poverty, Downloads July 2008-June 2009: 12,

A Mathematical Programming Formulation for the Budding Yeast Cell Cycle

The budding yeast cell cycle can be modeled by a set of ordinary differential equations with 143 rate constant parameters. The quality of the model (and an associated vector of parameter settings) is measured by comparing simulation results to the experimental data derived from observing the cell cycles of over 100 selected mutated forms. Unfortunately, determining whether the simulated phenotype matches experimental data is difficult since the experimental data tend to be qualitative in nature (i.e., whether the mutation is viable, or which development phase it died in). Because of this, previous methods for automatically comparing simulation results to experimental data used a discontinuous penalty function, which limits the range of techniques available for automated estimation of the differential equation parameters. This paper presents a system of smooth inequality constraints that will be satisfied if and only if the model matches the experimental data. Results are presented for evaluating the mutants with the two most frequent phenotypes. This nonlinear inequality formulation is the first step toward solving a large-scale feasibility problem to determine the ordinary differential equation model parameters

Enabling Small-Scale Maize Marketing and Processing to Assure Supplies of Low-Cost Staples

Crop Production/Industries, Downloads December 2008 - July 2009: 6,

By design : negotiating flexible learning in the built environment discipline

The term ‘flexible education’ is now firmly entrenched within Australian higher education discourse, yet the term is a contested one imbued with a multiplicity of meanings. This paper describes a process designed to elucidate how the idea of flexible education can be translated into teaching models that are informed by the specific demands of disciplinary contexts. The process uses a flexible learning ‘matching’ tool to articulate the understandings and preferences of students and academics of the Built Environment to bridge the gap between student expectations of flexibility and their teacher’s willingness and ability to provide that flexibility within the limits of the pedagogical context and teaching resources. The findings suggest an informed starting point for educators in the Built Environment and other creative disciplines from which to traverse the complexities inherent in negotiating flexibility in an increasingly digital world

Strongly correlated growth of Rydberg aggregates in a vapor cell

The observation of strongly interacting many-body phenomena in atomic gases typically requires ultracold samples. Here we show that the strong interaction potentials between Rydberg atoms enable the observation of many-body effects in an atomic vapor, even at room temperature. We excite Rydberg atoms in cesium vapor and observe in real-time an out-of-equilibrium excitation dynamics that is consistent with an aggregation mechanism. The experimental observations show qualitative and quantitative agreement with a microscopic theoretical model. Numerical simulations reveal that the strongly correlated growth of the emerging aggregates is reminiscent of soft-matter type systems