196 research outputs found
Measurement and Particle Statistics in the Szilard Engine
A Szilard Engine is a hypothetical device which is able to extract work from
a single thermal reservoir by measuring the position of particles within the
engine. We derive the amount of work that can be extracted from such a device
in the low temperature limit. Interestingly, we show this work is determined by
the information gain of the initial measurement rather than by the number and
type of particles which constitute the working substance. Our work provides
another clear connection between information gain and extractable work in
thermodynamical processes.Comment: 4 page
THE ANALYSIS OF THE EFFECTS OF LOVE VALUES IN KOREAN DRAMAS ON TAIWANESE VIEWERS--FROM THE PERSPECTIVE OF BUSINESS.
Korean dramas have played an influential role in Taiwanese society since they were first introduced into Taiwan. One of the most dominant themes in most Korean dramas is the theme of love. As a story topic, love accounts for about ninety percent of the themes dealt with by these dramas. By applying the theoretical idea of cultural proximity, and by using content analysis to analyze the underlying values contained in the dramas, this study examines the theme of love in these dramas. The data pool includes 10 popular Korean dramas aired between the years of 2008 and 2012. Using these 10 dramas as a sample, I examine whether contemporary feminist attitudes about women’s autonomy play a role in how Taiwanese audiences identify with stories about love in Korean dramas. Through interviews with four television station managers from companies including LTV, ETTV, Videoland Drama and ELTA, I also gathered information about the process of localization within Korean dramas. In addition to the above strategies, my study incorporates secondary data to analyze related reports and statistical data about Korean dramas
Equations over free inverse monoids with idempotent variables
We introduce the notion of idempotent variables for studying equations in
inverse monoids.
It is proved that it is decidable in singly exponential time (DEXPTIME)
whether a system of equations in idempotent variables over a free inverse
monoid has a solution. The result is proved by a direct reduction to solve
language equations with one-sided concatenation and a known complexity result
by Baader and Narendran: Unification of concept terms in description logics,
2001. We also show that the problem becomes DEXPTIME hard , as soon as the
quotient group of the free inverse monoid has rank at least two.
Decidability for systems of typed equations over a free inverse monoid with
one irreducible variable and at least one unbalanced equation is proved with
the same complexity for the upper bound.
Our results improve known complexity bounds by Deis, Meakin, and Senizergues:
Equations in free inverse monoids, 2007.
Our results also apply to larger families of equations where no decidability
has been previously known.Comment: 28 pages. The conference version of this paper appeared in the
proceedings of 10th International Computer Science Symposium in Russia, CSR
2015, Listvyanka, Russia, July 13-17, 2015. Springer LNCS 9139, pp. 173-188
(2015
All-optical formation of coherent dark states of silicon-vacancy spins in diamond
Spin impurities in diamond can be versatile tools for a wide range of
solid-state-based quantum technologies, but finding spin impurities which offer
sufficient quality in both photonic and spin properties remains a challenge for
this pursuit. The silicon-vacancy center has recently attracted a lot of
interest due to its spin-accessible optical transitions and the quality of its
optical spectrum. Complementing these properties, spin coherence is essential
for the suitability of this center as a spin-photon quantum interface. Here, we
report all-optical generation of coherent superpositions of spin states in the
ground state of a negatively charged silicon-vacancy center using coherent
population trapping. Our measurements reveal a characteristic spin coherence
time, T2*, exceeding 250 nanoseconds at 4 K. We further investigate the role of
phonon-mediated coupling between orbital states as a source of irreversible
decoherence. Our results indicate the feasibility of all-optical coherent
control of silicon-vacancy spins using ultrafast laser pulses.Comment: Additional data and analysis is available for download in PDF format
at the publications section of http://www.amop.phy.cam.ac.uk/amop-m
Dynamics of a mesoscopic nuclear spin ensemble interacting with an optically driven electron spin
The ability to discriminate between simultaneously occurring noise sources in
the local environment of semiconductor InGaAs quantum dots, such as electric
and magnetic field fluctuations, is key to understanding their respective
dynamics and their effect on quantum dot coherence properties. We present a
discriminatory approach to all-optical sensing based on two-color resonance
fluorescence of a quantum dot charged with a single electron. Our measurements
show that local magnetic field fluctuations due to nuclear spins in the absence
of an external magnetic field are described by two correlation times, both in
the microsecond regime. The nuclear spin bath dynamics show a strong dependence
on the strength of resonant probing, with correlation times increasing by a
factor of four as the optical transition is saturated. We interpret the
behavior as motional averaging of both the Knight field of the resident
electron spin and the hyperfine-mediated nuclear spin-spin interaction due to
optically-induced electron spin flips
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Environment-assisted quantum control of a solid-state spin via coherent dark states
Understanding the interplay between a quantum system and its environment lies at the heart of quantum science and its applications. So far most efforts have focused on circumventing decoherence induced by the environment by either protecting the system from the associated noise or by manipulating the environment directly. Recently, parallel efforts using the environment as a resource have emerged, which could enable dissipation-driven quantum computation and coupling of distant quantum bits. Here, we realize the optical control of a semiconductor quantum-dot spin by relying on its interaction with an adiabatically evolving spin environment. The emergence of hyperfine-induced, quasi-static optical selection rules enables the optical generation of coherent spin dark states without an external magnetic field. We show that the phase and amplitude of the lasers implement multi-axis manipulation of the basis spanned by the dark and bright states, enabling control via projection into a spin-superposition state. Our approach can be extended, within the scope of quantum control and feedback, to other systems interacting with an adiabatically evolving environment.We gratefully acknowledge financial support by the University of Cambridge, the European Research Council ERC Consolidator Grant agreement no. 617985, EU-FP7 Marie Curie Initial Training Network S3NANO, the NSF-funded Physics Frontier Center at the Joint Quantum Institute, and ARO MURI award no. W911NF0910406.
TEAD and YAP regulate the enhancer network of human embryonic pancreatic progenitors.
The genomic regulatory programmes that underlie human organogenesis are poorly understood. Pancreas development, in particular, has pivotal implications for pancreatic regeneration, cancer and diabetes. We have now characterized the regulatory landscape of embryonic multipotent progenitor cells that give rise to all pancreatic epithelial lineages. Using human embryonic pancreas and embryonic-stem-cell-derived progenitors we identify stage-specific transcripts and associated enhancers, many of which are co-occupied by transcription factors that are essential for pancreas development. We further show that TEAD1, a Hippo signalling effector, is an integral component of the transcription factor combinatorial code of pancreatic progenitor enhancers. TEAD and its coactivator YAP activate key pancreatic signalling mediators and transcription factors, and regulate the expansion of pancreatic progenitors. This work therefore uncovers a central role for TEAD and YAP as signal-responsive regulators of multipotent pancreatic progenitors, and provides a resource for the study of embryonic development of the human pancreas
Targeted kinase inhibition relieves slowness and tremor in a Drosophila model of LRRK2 Parkinson’s disease
Disease models: A reflex reaction A simple reflex in flies can be used to test the effectiveness of therapies that slow neurodegeneration in Parkinson’s disease (PD). Christopher Elliott and colleagues at the University of York in the United Kingdom investigated the contraction of the proboscis muscle which mediates a taste behavior response and is regulated by a single dopaminergic neuron. Flies bearing particular mutations in the PD-associated gene leucine-rich repeat kinase 2 (LRRK2) in dopaminergic neurons lost their ability to feed on a sweet solution. This was due to the movement of the proboscis muscle becoming slower and stiffer, hallmark features of PD. The authors rescued the impaired reflex reaction by feeding the flies l-DOPA or LRRK2 inhibitors. These findings highlight the proboscis extension response as a useful tool to identify other PD-associated mutations and test potential therapeutic compounds
A Comparison of Levels of Select Minerals in Scalp Hair Samples with Estimated Dietary Intakes of These Minerals in Women of Reproductive Age
The objective of this study was to evaluate daily intake of minerals and concentrations of minerals in hair in women of reproductive age. The study included 77 menstruating women, aged 35.9 ± 9.7 years. Subjects were divided into three groups according to age. All women were healthy. Hair samples were taken from several points of the occipital scalp. The content of minerals in hair samples was determined by flame atomic absorption spectrometry. Dietary intake of the analysed minerals was assayed on the basis of dietary intake interviews from three preceding days and evaluated using the dietetic computer programme. It was shown that calcium and iron daily intake by the women was below the recommended value. Only few women had low concentrations (below reference values) of magnesium, copper and zinc in hair. Statistically significant differences were shown between age groups. Generally, the concentrations of minerals in hair in the younger (19–30 years) and the older women (41–50 years) were higher than in hair of middle-aged women (31–40 years). The content of calcium, magnesium, iron and zinc in daily diets of women correlated inversely with copper level in their hair. Food products with good bioavailability of iron and calcium should be recommended for women of childbearing age in all age groups
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