2,747 research outputs found
Relations between Entropies Produced in Nondeterministic Thermodynamic Processes
Landauer's erasure principle is generalized to nondeterministic processes on
systems having an arbitrary number of non-symmetrical logical states. The
condition that the process is applied in the same way, irrespective of the
initial logical state, imposes some restrictions on the individual heat
exchanges associated with each possible transition. The complete set of such
restrictions are derived by a statistical analysis of the phase-space flow
induced by the process. Landauer's erasure principle can be derived from and is
a special case of these.Comment: 12 pages with one figure; a final major revision in presentation;
physical assumptions are clarified no
United States Policy Regarding Recognition of Foreign States
Recognition is the act whereby the executive of a nation formally acknowledges the existence of a new state or government and determines all of the legal consequences flowing from this act to the new state or government. The author of this note proposes that recognition should be founded upon international legal standards, rather than political considerations
Universal efficiency at optimal work with Bayesian statistics
If the work per cycle of a quantum heat engine is averaged over an
appropriate prior distribution for an external parameter , the work becomes
optimal at Curzon-Ahlborn efficiency. More general priors of the form yield optimal work at an efficiency which stays close to
CA value, in particular near equilibrium the efficiency scales as one-half of
the Carnot value. This feature is analogous to the one recently observed in
literature for certain models of finite-time thermodynamics. Further, the use
of Bayes' theorem implies that the work estimated with posterior probabilities
also bears close analogy with the classical formula. These findings suggest
that the notion of prior information can be used to reveal thermodynamic
features in quantum systems, thus pointing to a new connection between
thermodynamic behavior and the concept of information.Comment: revtex4, 5 pages, abstract changed and presentation improved; results
unchanged. New result with Bayes Theorem adde
Information erasure without an energy cost
Landauer argued that the process of erasing the information stored in a
memory device incurs an energy cost in the form of a minimum amount of
mechanical work. We find, however, that this energy cost can be reduced to zero
by paying a cost in angular momentum or any other conserved quantity. Erasing
the memory of Maxwell's demon in this way implies that work can be extracted
from a single thermal reservoir at a cost of angular momentum and an increase
in total entropy. The implications of this for the second law of thermodynamics
are assessed.Comment: 8 pages with 1 figure. Final published versio
Memory erasure in small systems
We consider an overdamped nanoparticle in a driven double-well potential as a
generic model of an erasable one-bit memory. We study in detail the statistics
of the heat dissipated during an erasure process and show that full erasure may
be achieved by dissipating less heat than the Landauer bound. We quantify the
occurrence of such events and propose a single-particle experiment to verify
our predictions. Our results show that Landauer's principle has to be
generalized at the nanoscale to accommodate heat fluctuations.Comment: 4 pages, 4 figure
Entropy of Measurement and Erasure: Szilard’s Membrane Model Revisited
It is widely believed that measurement is accompanied by irreversible entropy increase. This conventional wisdom is based in part on Szilard\u27s 1929 study of entropy decrease in a thermodynamic system by intelligent intervention (i.e., a Maxwell\u27s demon) and Brillouin\u27s association of entropy with information. Bennett subsequently argued that information acquisition is not necessarily irreversible, but information erasure must be dissipative (Landauer\u27s principle). Inspired by the ensuing debate, we revisit the membrane model introduced by Szilard and find that it can illustrate and clarify (1) reversible measurement, (2) information storage, (3) decoupling of the memory from the system being measured, and (4) entropy increase associated with memory erasure and resetting
Resource Letter MD-1: Maxwell\u27s Demon
This Resource Letter provides a comprehensive guide to the voluminous literature that has developed around Maxwell’s demon, and offers a perspective on issues for which the hypothetical character Maxwell introduced over 120 years ago has inspired continuing research and debate. The code (E) indicates elementary level or general interest material useful to persons just learning the field; (I) indicates intermediate level or somewhat specialized material; and (A) indicates advanced or highly specialized material. No accompanying AAPT reprint book will be available, because an extensive reprint collection (Ref. 29) edited by the authors will be published separately
Review: Peroxisome Proliferator-Activated Receptor-γ and Its Role in the Development and Treatment of Diabetes
Since its identification as the receptor for antidiabetic
thiazolidinedione drugs, peroxisome proliferator-activated
receptor-γ (PPARγ) has been the focus of pharmaceutical
drug discovery programs directed toward finding better
drugs for the treatment of diabetes, as well as the object
of basic research aimed at understanding its role in
the regulation of metabolism. We now understand a great
deal about the crucial role that PPARγ plays in adipocyte
differentiation and development, and are rapidly gaining
knowledge about the role of the receptor in the regulation
of metabolism. However, many crucial aspects of the molecular
mechanism by which modulation of PPARγ activity
affects insulin resistance and glucose homeostasis are still
not clearly understood. Here the authors review the current
status of PPARγ research, with an emphasis on its role in
the causes and treatment of type 2 diabetes
Efficiency of a Brownian information machine
A Brownian information machine extracts work from a heat bath through a
feedback process that exploits the information acquired in a measurement. For
the paradigmatic case of a particle trapped in a harmonic potential, we
determine how power and efficiency for two variants of such a machine operating
cyclically depend on the cycle time and the precision of the positional
measurements. Controlling only the center of the trap leads to a machine that
has zero efficiency at maximum power whereas additional optimal control of the
stiffness of the trap leads to an efficiency bounded between 1/2, which holds
for maximum power, and 1 reached even for finite cycle time in the limit of
perfect measurements.Comment: 9 pages, 2 figure
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