Error-Resistant Distributed Quantum Computation in Trapped Ion Chain

We consider experimentally feasible chains of trapped ions with pseudo-spin 1/2, and find models that can potentially be used to implement error-resistant quantum computation. Similar in spirit to classical neural networks, the error-resistance of the system is achieved by encoding the qubits distributed over the whole system. We therefore call our system a ''quantum neural network'', and present a ''quantum neural network model of quantum computation''. Qubits are encoded in a few quasi-degenerated low energy levels of the whole system, separated by a large gap from the excited states, and large energy barriers between themselves. We investigate protocols for implementing a universal set of quantum logic gates in the system, by adiabatic passage of a few low-lying energy levels of the whole system. Naturally appearing and potentially dangerous distributed noise in the system leaves the fidelity of the computation virtually unchanged, if it is not too strong. The computation is also naturally resilient to local perturbations of the spins.Comment: 10 pages, 7 figures, RevTeX4; v2: another noise model analysed, published versio

Spatial evolution of an AMD stream in the Iberian Pyrite Belt: process characterization and control factors on the hydrochemistry

This paper presents hydrochemical data of an AMD stream in the Iberian Pyrite Belt, obtained from its source, in the Poderosa Mine Portal, till its confluence at the Odiel River. The main objective is to establish potential interdependent relations between sulfate and metals’ loads and the following physical-chemical variables: pH, electric conductivity (EC), redox potential (EH), and dissolved oxygen (O2). All the parameters show a global increasing tendency since the tunnel’s exit to the confluence at Odiel River. The TDS and EC are two relevant exceptions. They behave similarly, showing a decreasing trend and a strong inflection that describes a minimum immediately after the discharging point. The spatial analysis combined with statistical tools put in evidence the typical AMD processes and the respective physical-chemical implications. Inputs with distinctive hydrochemical signatures impose relevant modifications in the Poderosa creek waters. This indicates low hydrochemical inertia and high vulnerability to external stimulus.Financial support for this research was provided by DGCICYT National Plan, project CGL2010-21268-C02-01 and the Andalusian Autonomous Government Excellence Projects, Project RNM-6570

In-situ trace metal (Cd, Pb, Cu) speciation along the Po River plume (Northern Adriatic Sea) using submersible systems

Highlights • In-situ trace metal speciation in the Adriatic Sea by submersible voltammetric sensors • Metal species distribution mainly affected by Po River outflow. • Metal dynamic concentrations below legal limits • Cu dynamic concentrations toxic to sensitive phytoplankton Abstract Information on the distribution and speciation of trace metals is of critical importance for our ability to interpret the links between the bioavailability and uptake of an element, and its biogeochemical cycle in coastal environments. Within the framework of the European Project “In-situ automated Monitoring of Trace metal speciation in Estuaries and Coastal zones in relation with the biogeochemical processes (IMTEC)”, the chemical speciation of Cd, Pb and Cu was carried out along the Po River plume in the period 27 October – 2 November 2002. During the cruise, five Voltammetric In-situ Profiling systems and one Multi Physical Chemical Profiler, as well as conventional voltammetric instruments, were successfully applied in order to evaluate the distribution of Cd, Pb and Cu between different fractions (free ion, dynamic, colloidal, dissolved and particulate fractions) and to assess the evolution of these fractions during estuarine mixing and in the water column. Dynamic concentrations were 0.05–0.2 nmol L−1 Cd, 0.02–0.2 nmol L−1 Pb, and 0.15–4.0 nmol L−1Cu. Cd was mainly present as dynamic fraction (40–100% of the dissolved Cd). High proportions of Pb (~70%) and Cu (~80%) were present as colloids probably of biogenic origin. Principal components analysis reveals a strong influence of the Po River discharge on the spatial and vertical distributions of metal species. Almost all the metal fractions globally decreased following the salinity gradient. Metal concentrations are far below (at least one order of magnitude lower) the Environmental Quality Standard established by the Italian law. However, the Cu dynamic fraction showed concentrations likely to be toxic to sensitive phytoplankton community and to have negative effects on larva development of coastal macroinvertebrate species (toxicity data extracted from literature)

Refrigerant Charge in Heat Pumps - Part II - Charge Reduced Heat Pump Design

This second part of the article series about refrigerant charge reduction in heat pumps is intended to provide an overview of ways of designing a charge-reduced heat pump. A close look at each of the main components of the heat pump reveals its potentials for charge reduction

Measurement of a R290 leakage with laser doppler anemometry

This paper describes the experience made with the measurement of the velocity field of a plume of leaking R290 into an air-filled space with Laser Doppler Anemometry. Two different leak sizes were tested with both liquid and vapour refrigerant

Towards a More Realistic Cost-Benefits Analysis - Attempting to Integrate Transaction Costs and Energy Efficiency Services

In order to calculate the financial return of energy efficiency measures, a cost-benefit analysis (CBA) is a proven tool for investors. Generally, however, most CBAs for investors have a narrow focus, which is - simply speaking - on investment costs compared with energy cost savings over the life span of the investment. This only provides part of the full picture. Ideally, a comprehensive or extended CBA would take additional benefits as well as additional costs into account. The objective of this paper is to reflect upon integrating into a CBA two important cost components: transaction costs and energy efficiency Services - and how they interact. Even though this concept has not been carried out to the knowledge of the authors, we even go a step further to try to apply this idea. In so doing, we carried out a meta-analysis on relevant literature and existing data and interviewed a limited number of energy experts with comprehensive experience in carrying out energy services. Even though data is hardly available, we succeeded in constructing three real-world cases and applied an extended CBA making use of information gathered on transaction costs and energy services costs. We were able to show that, despite these additional cost components, the energy efficiency measures are economically viable. Quantitative data was not available on how energy services reduce transaction costs; more information on this aspect could render our results even more positive. Even though empirical and conceptual research must intensify efforts to design an even more comprehensive CBA, these first-of-its-kind findings can counterargue those that believe energy efficiency is not worth it (in monetary terms) due to transaction costs or energy services costs. In fact, this is good news for energy efficiency and for those that seek to make use of our findings to argue in favor of taking up energy efficiency investments in businesses

Natural circulation defrosting with propane in horizontal evaporators of large capacity air-to water heat pump

This paper presents natural circulation defrosting for a large capacity horizontally mounted evaporator designed for a propane refrigeration cycle. This defrosting method is based on a two-phase thermosiphon. It is mounted as an additional loop next to a nominal refrigeration circuit to allow switching between the completely different requirements for refrigerant charge either in nominal heat pump operation or in defrosting mode. A fin-and-tube heat exchanger with 5mm round tube with a conventional 32 port nozzle distributor was successfully tested. Considered design criteria, thermal performance and analysis of the defrosting process are presented

Nursing schools and academic health centers: toward improved alignment and a synergistic partnership

Azita Emami,1 Darcy Jaffe,2 Paula Minton-Foltz,3 Grace Parker,4 Susan Manfredi,5 Theresa Braungardt,6 Kelly W Marley,1 Laura Cooley,1 Staishy Bostick Siem7 1University of Washington School of Nursing, Seattle, WA, USA; 2Harborview Medical Center, University of Washington Medicine, Seattle, WA, USA; 3Patient Care Services, Harborview Medical Center, University of Washington Medicine, Seattle, WA, USA; 4University of Washington Medical Center, Seattle, WA, USA; 5Patient Care Services, Northwest Hospital and Medical Center, Seattle, WA, USA; 6Valley Medical Center, Seattle, WA, USA; 7Marketing and Communications, University of Washington School of Nursing, Seattle, WA, USA Abstract: This paper presents the findings from a national survey which the University of Washington conducted among leaders of 32 US academic nursing institutions that are part of academic health centers (AHCs) and complements these findings with results from a separate report by the American Association of Colleges of Nursing. While expressing overall satisfaction with their AHC relationships, these leaders find that nursing is often given greater parity in matters of education and research than in mission setting, financial, and governance matters. AHCs are being asked to meet new health care challenges in new ways, starting with the education of health care professionals. AHCs need to be restructured to give nursing full parity if the nation’s and world’s needs for preventive and clinical care are to be best met.Keywords: nursing parity, academic nursing institutions, nurse leaders, institutional alignmen

Theoretical pathways towards experimental quantum simulators

Recent progress in quantum optics and quantum information has brought the long-standing dreams of quantum simulators and even quantum computers (almost) within reach. Here, we review some current theoretical pathways supporting experimental progress towards quantum simulators. In this, we focus mainly on topological aspects and numerical studies of quantum computation. © Sociedad Española de Óptica.This work was funding by the Spanish MEC projects TOQATA (FIS2008-00784), QOIT (Consolider Ingenio 2010), ACUTE, ERC Advanced Grant QUAGATUA, EU STREP NAMEQUAM, partly (E. Sz.) by the Hungarian Research Fund (OTKA) under Grant No. 68340, the Barcelona Supercomputing Center - Centro Nacional de Supercomputación (FI2008-3-0029, FI2009-1-0019) (A.N.), and Alexander von Humboldt Foundation (M.L.).Peer Reviewe