On the beneficial role of noise in resistive switching

We study the effect of external noise on resistive switching. Experimental results on a manganite sample are presented showing that there is an optimal noise amplitude that maximizes the contrast between high and low resistive states. By means of numerical simulations, we study the causes underlying the observed behavior. We find that experimental results can be related to general characteristics of the equations governing the system dynamics.Comment: 4 pages, 5 figure

Elementary excitation families and their frequency ordering in cylindrically symmetric Bose-Einstein condensates

We present a systematic classification of the elementary excitations of Bose-Einstein condensates in cylindrical traps in terms of their shapes. The classification generalizes the concept of families of excitations first identified by Hutchinson and Zaremba (1998) Phys. Rev. A 57 1280 by introducing a second classification number that allows all possible modes to be assigned to a family. We relate the energy ordering of the modes to their family classification, and provide a simple model which explains the relationship.Comment: 15 pages, 8 figures; abstract complemented, section 4.2 shortened, references corrected; to be published in J. Phys.

How to Grow Strawberries in the Home Garden

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A new paradigm of governance for a carbon-pricing system

Throughout its life, the United Nations has played a pioneering role in the world of ideas. COP21 – also known as Paris 2015 – shows the path for the United Nations to establish a new governance that will enforce the compliance of a new planetary carbon-pricing system. Maintaining global warming below 2 °C means implementing an efficient carbon-pricing system, supported by effective measures promoting a green energy transition. A planetary carbon governance yields a number of new insights that include the following: (1) a bonus-malus system with a fixed signal price for carbon, (2) a planetary carbon market that will gather existing regional carbon markets, (3) a hybrid carbon-pricing system linking a carbon tax and a carbon market for advanced countries and (4) a support mechanism for emerging and developing countries to assist them with a carbon-pricing system. This new governance will promote an energy transition plan. In the COP21 context, responsible policymaking requires key characteristics for the enforcement of a successful planetary carbon-pricing system

Sub-visual Cirrus detection and characterization

Analysis of archived cold optics (COR) radiometer data is yielding useful information on the diurnal, geographic, seasonal and altitude variability of atmospheric background radiance levels in the 11 micron window region. This database is a compilation of Kuiper Infrared Technology Experiment (KITE) and Atmospheric Radiance Study (ARS) observations under a wide variety of conditions. Correlating the measurements from these two studies with the LOWTRAN model code has revealed several important results. First, the 11 micron window appears to be filled-in, i.e., the troughs on either side of the nitric acid peak are shallower than expected. Second, the amplitude of the background radiances measured exceeds the model predictions by a factor of 2 to 3 or more. This is thought to be due to the existence of thin, high altitude cirrus clouds (sub-visual cirrus) above the sensor platform. These high background levels are observed under quiescent conditions in the South Pacific (Marshall Islands), as well as over the continental United States (the West Coast). In the tropics, there appears to be little diurnal variability, a plausible seasonal variation and a linear dependence between 7.2 and 11.4 micron band data, indicating possible multi-spectral approaches to detection of sub-visual cirrus clouds. Theoretical analysis of the magnitude of the effects of a sub-visual cirrus cloud on atmospheric background radiances measured by a near-horizontal sensor is in progress

The well-being of British expatriate retirees in southern Europe

This article examines the personal outcomes of overseas residence in later life, by analysing some findings from the first large-scale, comparative study of the retirement of British citizens to southern Europe. Four study areas are compared: Tuscany in Italy, Malta, the Costa del Sol of Spain, and the Algarve region of Portugal. The analysis focuses on the expressed reasons for moving to and residing in the areas, the reported advantages and disadvantages, and the respondents' predictions of whether they would stay or leave in response to adverse and beneficial events. Overall the subjects give very positive reports, but there are considerable differences among the four areas. The associations of individual variation in well-being with both a person's ‘temporal commitment’ to the area and to facets of their social integration are analysed. The onset of severe incapacity, sufficient to prevent the continued running of a home, is the event most likely to cause people to leave their adopted areas of residence

Apollo experience report: Guidance and control systems: Command and service module entry monitor subsystem

The conceptual aspects of the command and service module entry monitor subsystem, together with an interpretation of the displays and their associated relationship to entry trajectory control, are presented. The entry monitor subsystem is described, and the problems encountered during the developmental phase and the first five manned Apollo flights are discussed in conjunction with the design improvements implemented

Coercivity of domain wall motion in thin films of amorphous rare earth-transition metal alloys

Computer simulations of a two dimensional lattice of magnetic dipoles are performed on the Connection Machine. The lattice is a discrete model for thin films of amorphous rare-earth transition metal alloys, which have application as the storage media in erasable optical data storage systems. In these simulations, the dipoles follow the dynamic Landau-Lifshitz-Gilbert equation under the influence of an effective field arising from local anisotropy, near-neighbor exchange, classical dipole-dipole interactions, and an externally applied field. Various sources of coercivity, such as defects and/or inhomogeneities in the lattice, are introduced and the subsequent motion of domain walls in response to external fields is investigated

Exploratory wind-tunnel investigation of a wingtip-mounted vortex turbine for vortex energy recovery

The Langley 8-foot transonic pressure tunnel was used for tests to determine the possibility of recovering, with a turbine-type device, part of the energy loss associated with the lift-induced vortex system. Tests were conducted on a semispan model with an unswept, untapered wing, with and without a wingtip-mounted vortex turbine. Three sets of turbine blades were tested to determine the effect of airfoil section shape and planform. The tests were conducted at a Mach number of 0.70 over an angle-of-attack range from 0 deg. to 4 deg. at a Reynolds number of 3.82 x 10 to the 6th power based on the wing reference chord of 13 in