Isotopic variation of parity violation in atomic ytterbium

We report on measurements of atomic parity violation, made on a chain of ytterbium isotopes with mass numbers A=170, 172, 174, and 176. In the experiment, we optically excite the 6s2 1S0 -> 5d6s 3D1 transition in a region of crossed electric and magnetic fields, and observe the interference between the Stark- and weak-interaction-induced transition amplitudes, by making field reversals that change the handedness of the coordinate system. This allows us to determine the ratio of the weak-interaction-induced electric-dipole (E1) transition moment and the Stark-induced E1 moment. Our measurements, which are at the 0.5% level of accuracy for three of the four isotopes measured, allow a definitive observation of the isotopic variation of the weak-interaction effects in an atom, which is found to be consistent with the prediction of the Standard Model. In addition, our measurements provide information about an additional Z' boson.Comment: 19 pages, 4 figures, 2 table

Photoconductance Quantization in a Single-Photon Detector

We have made a single-photon detector that relies on photoconductive gain in a narrow electron channel in an AlGaAs/GaAs 2-dimensional electron gas. Given that the electron channel is 1-dimensional, the photo-induced conductance has plateaus at multiples of the quantum conductance 2e$^{2}$/h. Super-imposed on these broad conductance plateaus are many sharp, small, conductance steps associated with single-photon absorption events that produce individual photo-carriers. This type of photoconductive detector could measure a single photon, while safely storing and protecting the spin degree of freedom of its photo-carrier. This function is valuable for a quantum repeater that would allow very long distance teleportation of quantum information.Comment: 4 pages, 4 figure

ASCR/HEP Exascale Requirements Review Report

This draft report summarizes and details the findings, results, and recommendations derived from the ASCR/HEP Exascale Requirements Review meeting held in June, 2015. The main conclusions are as follows. 1) Larger, more capable computing and data facilities are needed to support HEP science goals in all three frontiers: Energy, Intensity, and Cosmic. The expected scale of the demand at the 2025 timescale is at least two orders of magnitude -- and in some cases greater -- than that available currently. 2) The growth rate of data produced by simulations is overwhelming the current ability, of both facilities and researchers, to store and analyze it. Additional resources and new techniques for data analysis are urgently needed. 3) Data rates and volumes from HEP experimental facilities are also straining the ability to store and analyze large and complex data volumes. Appropriately configured leadership-class facilities can play a transformational role in enabling scientific discovery from these datasets. 4) A close integration of HPC simulation and data analysis will aid greatly in interpreting results from HEP experiments. Such an integration will minimize data movement and facilitate interdependent workflows. 5) Long-range planning between HEP and ASCR will be required to meet HEP's research needs. To best use ASCR HPC resources the experimental HEP program needs a) an established long-term plan for access to ASCR computational and data resources, b) an ability to map workflows onto HPC resources, c) the ability for ASCR facilities to accommodate workflows run by collaborations that can have thousands of individual members, d) to transition codes to the next-generation HPC platforms that will be available at ASCR facilities, e) to build up and train a workforce capable of developing and using simulations and analysis to support HEP scientific research on next-generation systems.Comment: 77 pages, 13 Figures; draft report, subject to further revisio

Coherent amplitude modulation of continuous-wave light in cesium vapor

We report on observations of coherent, sustained oscillations in the absorption of continuous-wave light at 388 nm that excites the $6S_{1/2}\rightarrow 8P_{3/2}$ transition in cesium vapor. The oscillation frequency is close to the spacing of hyperfine levels of the $8P_{3/2}$ level that are excited simultaneously by the 388 nm field. We observe threshold behavior of the oscillation amplitude with pump power, and suggest that the effect is associated with infrared directional emission due to amplified spontaneous emission from the $8P_{3/2}\rightarrow 8S_{1/2}$ transition, that is assisted by retro-reflections from the cell windows. The effect may be used to probe a lasing process in an atomic vapor, by checking the temporal properties of the pump field transmitted through the vapor

Methodology for integrated socio-economic assessment of offshore platforms : towards facilitation of the implementation of the marine strategy framework directive

In this paper a Methodology for Integrated Socio-Economic Assessment (MISEA) of the viability and sustainability of different designs of Multi-Use Offshore Platforms (MUOPs) is presented. MUOPs are designed for multi-use of ocean space for energy extraction (wind power production and wave energy), aquaculture and transport maritime services. The developed methodology allows identification, valuation and assessment of: the potential range of impacts of a number of feasible designs of MUOP investments, and the likely responses of those impacted by the investment project. This methodology provides decision-makers with a valuable decision tool to assess whether a MUOP project increases the overall social welfare and hence should be undertaken, under alternative specifications regarding its design, the discount rate and the stream of net benefits, if a Cost-Benefit Analysis (CBA) is to be followed or sensitivity analysis of selected criteria in a Multi-Criteria Decision Analysis (MCDA) framework. Such a methodology is also crucial for facilitating of the implementation of the Marine Strategy Framework Directive (MSFD adopted in June 2008) that aims to achieve good environmental status of the EU's marine waters by 2020 and to protect the resource base upon which marine-related economic and social activities depend. According to the MSFD each member state must draw up a program of cost-effective measures, while prior to any new measure an impact assessment which contains a detailed cost-benefit analysis of the proposed measures is required

Post-Disaster Recovery Assessment Using Sentiment Analysis of English-Language Tweets: A Tenth-Anniversary Case Study of the 2010 Haiti Earthquake

\ua9 2025 by the authors. The 2010 Haiti earthquake stands as one of the most catastrophic events in terms of loss of life and destruction. Following an earthquake, there is an urgent demand for information. Regrettably, few studies have tracked the progress of the post-disaster recovery, leaving this phase poorly understood. In previous years, data were exclusively collected through on-site missions, but today, social media (SM) has enhanced earthquake reconnaissance teams’ capacity to collect data beyond the emergency phase. However, text data from SM is unstructured, making it necessary to use natural language processing techniques to extract meaningful information. Sentiment analysis (SA), which classifies people’s opinions into positive, negative, or neutral polarity, is a promising tool for understanding earthquake recovery. For the purposes of this paper, we conduct SA at the tweet level on data collected around the tenth anniversary of the earthquake using human expertise to fine-tune automatic classification methods. We conclude that the anniversary date is the best time to collect data. In our sample, 56.3% of the tweets in the sample were classified as negative, followed by positive (27.3%), neutral (8.2%), and unrelated (8.1%). In our study, we conclude that the assessment of the recovery progress based on data collected from Twitter is negative. The automatic method for SA with the highest accuracy is ‘btweet’. The assessment result must be validated by stakeholders