11,623 research outputs found
Observable geometric phase induced by a cyclically evolving dissipative process
In a prevous paper (Phys. Rev. Lett. 96, 150403 (2006)) we have proposed a
new way to generate an observable geometric phase on a quantum system by means
of a completely incoherent phenomenon. The basic idea was to force the ground
state of the system to evolve ciclically by "adiabatically" manipulating the
environment with which it interacts. The specific scheme we have previously
analyzed, consisting of a multilevel atom interacting with a broad-band
squeezed vacuum bosonic bath whose squeezing parameters are smoothly changed in
time along a closed loop, is here solved in a more direct way. This new
solution emphasizes how the geometric phase on the ground state of the system
is indeed due to a purely incoherent dynamicsComment: 6 pages, 1 figur
Following Snowden: A Cross-cultural Study on the Social Impact of Snowden's Revelations
Purpose – This paper introduces a cross-cultural study of the views and implications of Snowden's
revelations about NSA/GCHQ surveillance practices, undertaken through surveys administered in
eight countries. The aims and the academic and social significance are explained and justification
offered for the methods used.
Design/methodology/approach – Pilot surveys were deployed in two countries, following which
revised versions were deployed in eight countries (including new collection in the original pilot
countries). Quantitative analysis of suitable answer sets (Yes/No; Likert scales) and quantitative
analysis (interpretation of free text answers) were performed.
Findings – Through the pilot survey studies conducted in Japan and Spain, the academic
significance and validity as well as social significance of the project were confirmed.
Social implications – The results of the cross-cultural study are expected to contribute not only to
the advance of surveillance studies but also to the enhancement of ordinary, non-technical people's
awareness of state surveillance and their proactive approach to protecting their own rights and
dignity from covert intrusion by government agencies.
Originality/value – This paper clarifies the importance and methodologies of investigating the
social impact of Snowden's revelations on youngsters' attitudes toward privacy and state
surveillance in a cross-cultural analysis framework. Although a few other studies have looked at the
impact of Snowden's revelations, these have mostly focussed on the US, so this is the only study to
date considering that impact on a broad international scale, using highly similar surveys to ensure
comparability. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down
Characterizing Atacama B-mode Search Detectors with a Half-Wave Plate
The Atacama B-Mode Search (ABS) instrument is a cryogenic (10 K)
crossed-Dragone telescope located at an elevation of 5190 m in the Atacama
Desert in Chile that observed for three seasons between February 2012 and
October 2014. ABS observed the Cosmic Microwave Background (CMB) at large
angular scales () to limit the B-mode polarization spectrum around
the primordial B-mode peak from inflationary gravity waves at .
The ABS focal plane consists of 480 transition-edge sensor (TES) bolometers.
They are coupled to orthogonal polarizations from a planar ortho-mode
transducer (OMT) and observe at 145 GHz. ABS employs an ambient-temperature,
rapidly rotating half-wave plate (HWP) to mitigate systematic effects and move
the signal band away from atmospheric noise, allowing for the recovery of
large angular scales. We discuss how the signal at the second harmonic of the
HWP rotation frequency can be used for data selection and for monitoring the
detector responsivities.Comment: 7 pages, 3 figures, conference proceedings submitted to the Journal
of Low Temperature Detector
Membrane-less organic-inorganic aqueous flow batteries with improved cell potential
A membrane-less organic-inorganic flow battery based on zinc and quinone species is proposed. By virtue of the slow dissolution rate of the deposited anode (<11.5 mg h-1 cm-2), the battery has a cell voltage of ca. 1.52 V with an average energy efficiency of ca. 73 at 30 mA cm-2 over 12 cycles
The Extended Shapes of Galactic Satellites
We are exploring the extended stellar distributions of Galactic satellite
galaxies and globular clusters. For seven objects studied thus far, the
observed profile departs from a King function at large r, revealing a ``break
population'' of stars. In our sample, the relative density of the ``break''
correlates to the inferred M/L of these objects. We discuss opposing hypotheses
for this trend: (1) Higher M/L objects harbor more extended dark matter halos
that support secondary, bound, stellar ``halos''. (2) The extended populations
around dwarf spheroidals (and some clusters) consist of unbound, extratidal
debris from their parent objects, which are undergoing various degrees of tidal
disruption. In this scenario, higher M/L ratios reflect higher degrees of
virial non-equilibrium in the parent objects, thus invalidating a precept
underlying the use of core radial velocities to obtain masses.Comment: 8 pages, including 2 figures Yale Cosmology Workshop: The Shapes of
Galaxies and Their Halo
Decoherence Rate of Semiconductor Charge Qubit Coupled to Acoustic Phonon Reservoir
We analyze decoherence of an electron in a double-dot due to the interaction
with acoustic phonons. For large tunneling rates between the quantum dots, the
main contribution to decoherence comes from the phonon emission relaxation
processes, while for small tunneling rates, the virtual-phonon, dephasing
processes dominate. Our results show that in common semiconductors, such as Si
and GaAs, the latter mechanism determines the upper limit for the double-dot
charge qubit performance measure.Comment: 4 pages, 2 figures, typos corrected, fig. 2 replaced by the improved
versio
Mineralogy of Interplanetary Dust Particles from the Comet Giacobini-Zinner Dust Stream Collections
The Draconoid meteor shower, originating from comet 21P/Giacobini-Zinner, is a low-velocity Earth-crossing dust stream that had a peak anticipated flux on Oct. 8, 2012. In response to this prediction, NASA performed dedicated stratospheric dust collections to target interplanetary dust particles (IDPs) from this comet stream on Oct 15-17, 2012 [3]. Twelve dust particles from this targeted collection were allocated to our coordinated analysis team for studies of noble gas (Univ. Minnesota, Minnesota State Univ.), SXRF and Fe-XANES (SSL Berkeley) and mineralogy/isotopes (JSC). Here we report a mineralogical study of 3 IDPs from the Draconoid collection.
Membrane-less hybrid flow battery based on low-cost elements
The capital cost of conventional redox flow batteries is relatively high (>USD$ 200/kWh) due to the use of expensive active materials and ion-exchange membranes. This paper presents a membrane-less hybrid organic-inorganic flow battery based on the low-cost elements zinc (92.7% with the use of carbon felt electrodes. In the presence of a fully oxidized active species close to its solubility limit, dissolution of the deposited anode is relatively slow (<2.37 g h−1 cm−2) with an equivalent corrosion current density of <1.9 mA cm−2. In a parallel plate flow configuration, the resulting battery was charge-discharge cycled at 30 mA cm−2 with average coulombic and energy efficiencies of c.a. 71.8 and c.a. 42.0% over 20 cycles, respectively
Low Energy Branes, Effective Theory and Cosmology
The low energy regime of cosmological BPS-brane configurations with a bulk
scalar field is studied. We construct a systematic method to obtain
five-dimensional solutions to the full system of equations governing the
geometry and dynamics of the bulk. This is done for an arbitrary bulk scalar
field potential and taking into account the presence of matter on the branes.
The method, valid in the low energy regime, is a linear expansion of the system
about the static vacuum solution. Additionally, we develop a four-dimensional
effective theory describing the evolution of the system. At the lowest order in
the expansion, the effective theory is a bi-scalar tensor theory of gravity.
One of the main features of this theory is that the scalar fields can be
stabilized naturally without the introduction of additional mechanisms,
allowing satisfactory agreement between the model and current observational
constraints. The special case of the Randall-Sundrum model is discussed.Comment: 19 pages, 4 figure
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