844 research outputs found
The maximum efficiency of nano heat engines depends on more than temperature
Sadi Carnot's theorem regarding the maximum efficiency of heat engines is
considered to be of fundamental importance in thermodynamics. This theorem
famously states that the maximum efficiency depends only on the temperature of
the heat baths used by the engine, but not on the specific structure of baths.
Here, we show that when the heat baths are finite in size, and when the engine
operates in the quantum nanoregime, a revision to this statement is required.
We show that one may still achieve the Carnot efficiency, when certain
conditions on the bath structure are satisfied; however if that is not the
case, then the maximum achievable efficiency can reduce to a value which is
strictly less than Carnot. We derive the maximum efficiency for the case when
one of the baths is composed of qubits. Furthermore, we show that the maximum
efficiency is determined by either the standard second law of thermodynamics,
analogously to the macroscopic case, or by the non increase of the max relative
entropy, which is a quantity previously associated with the single shot regime
in many quantum protocols. This relative entropic quantity emerges as a
consequence of additional constraints, called generalized free energies, that
govern thermodynamical transitions in the nanoregime. Our findings imply that
in order to maximize efficiency, further considerations in choosing bath
Hamiltonians should be made, when explicitly constructing quantum heat engines
in the future. This understanding of thermodynamics has implications for
nanoscale engineering aiming to construct small thermal machines.Comment: Main text 14 pages. Appendix 60 pages. Accepted in Journal Quantu
Improving Palliative Care with Deep Learning
Improving the quality of end-of-life care for hospitalized patients is a
priority for healthcare organizations. Studies have shown that physicians tend
to over-estimate prognoses, which in combination with treatment inertia results
in a mismatch between patients wishes and actual care at the end of life. We
describe a method to address this problem using Deep Learning and Electronic
Health Record (EHR) data, which is currently being piloted, with Institutional
Review Board approval, at an academic medical center. The EHR data of admitted
patients are automatically evaluated by an algorithm, which brings patients who
are likely to benefit from palliative care services to the attention of the
Palliative Care team. The algorithm is a Deep Neural Network trained on the EHR
data from previous years, to predict all-cause 3-12 month mortality of patients
as a proxy for patients that could benefit from palliative care. Our
predictions enable the Palliative Care team to take a proactive approach in
reaching out to such patients, rather than relying on referrals from treating
physicians, or conduct time consuming chart reviews of all patients. We also
present a novel interpretation technique which we use to provide explanations
of the model's predictions.Comment: IEEE International Conference on Bioinformatics and Biomedicine 201
Experimental implementation of bit commitment in the noisy-storage model
Fundamental primitives such as bit commitment and oblivious transfer serve as
building blocks for many other two-party protocols. Hence, the secure
implementation of such primitives are important in modern cryptography. In this
work, we present a bit commitment protocol which is secure as long as the
attacker's quantum memory device is imperfect. The latter assumption is known
as the noisy-storage model. We experimentally executed this protocol by
performing measurements on polarization-entangled photon pairs. Our work
includes a full security analysis, accounting for all experimental error rates
and finite size effects. This demonstrates the feasibility of two-party
protocols in this model using real-world quantum devices. Finally, we provide a
general analysis of our bit commitment protocol for a range of experimental
parameters.Comment: 21 pages (7 main text +14 appendix), 6+3 figures. New version changed
author's name from Huei Ying Nelly Ng to Nelly Huei Ying Ng, for consistency
with other publication
Filipino Bands Performing Hotels, Clubs, and Restaurants in Asia: Purveyors of Transnational Culture In a Global Arena
Filipino musicians can be found performing in many cities throughout Asia. They
form the largest and most widely dispersed population of traveling entertainers in Asia.
Their performance venues include five-star hotels, cruise liners, international chain pubs
and restaurants like the Hard Rock Café and Planet Hollywood, and tiny karaoke lounges
in Japan where entertaining entails singing karaoke with guests. Many Filipino
musicians aspire to perform abroad because of the higher salaries and status it confers
upon them. International hotels, and upscale clubs and restaurants are the mainstay for a
large proportion of Filipino entertainers. Their audience ranges from tourists and business
travelers to expatriates working for multinational corporations, and the local middle and
upper classes. They are in demand in these venues for their ability to perform mainstream
western pop and rock in the most ‘authentic’ style, including the ‘oldies’ and the latest
2
hits on the British and the American music charts. By ‘authentic,’ I mean they are able to
imitate the voice quality, singing style, and dance movements of well-known singers
from Britain and the United States. Filipino musicians are also in demand in Asia
because they can sing and speak in many different languages and can appeal to the local
audiences in the different countries where they perform.
This dissertation examines the reasons behind the demand of Filipino bands
performing Anglo-American mainstream popular music in Asia. It looks at the ways
globalization has facilitated working transnationally, and explores the culture Filipino
musicians employ in order to adapt to changing work environments. This dissertation
also reveals the ways in which transnationals influence the culture of those in their own
homeland and in the countries in which they are employed. This study will show that
Filipino bands provide a ‘global performance,’ involving the singing of Anglo-American
mainstream popular music, Asian hit songs, and international hits in other languages such
as Spanish and Italian, so that they can cater to the entertainments need of their diverse
audiences throughout Asia. Their performances reflect the global imaginings of their
audiences in Asia, while their experiences abroad shape the global imagination of
Filipinos in their homeland.Ph.D.Music: MusicologyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/58624/1/ng_stephanie_dissertation.pd
Investigation of intramolecular [2+2] photocycloadditions : using new cycloaddition/fragmentation strategies toward medium ring-containing natural products
Thesis advisor: Marc L. SnapperIntramolecular [2+2] photocycloadditions have been studied: (i) Previous studies in our group have demonstrated that there is a regiochemical dependence of intramolecular [2+2] photocycloadditions on the solvent employed. In order to understand the generality of hydrogen bonding effects of photochemical reactions of β-hydroxyl enones, we examined the photochemical outcome of enones with both acyclic and cyclic olefin tethers. (ii) An application of an intramolecular [2+2] photocycloaddition/ fragmentation strategy to form 5-8-5 ring systems has been demonstrated toward the synthesis of the natural product cycloaraneosene.Thesis (PhD) — Boston College, 2008.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Chemistry
The second laws of quantum thermodynamics
10.1073/pnas.1411728112Proceedings of the National Academy of Sciences of the United States of America112113275-327
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