1,727 research outputs found
An unusual cause of difficult weaning in a patient with newly diagnosed small cell lung cancer
AbstractWe describe a patient with acute respiratory insufficiency and difficult ventilator weaning in the ICU ward, leading to diagnosis of small cell lung cancer with superior vena cava superior syndrome. Bilateral vocal cord paralysis caused his respiratory distress and weaning difficulties. Thyroidectomy and neurological problems (such as Parkinson disease and Guillain Barré syndrome) are more common causes of bilateral vocal cord paralysis. Lung cancer patients are also at risk due to mediastinal invasion. The left recurrent laryngeal nerve is more prone to paralysis because of the typical anatomy. In contrary, bilateral vocal cord paralysis is rare and doesn't result in speech problems but rather breathing difficulties. Tracheostomy is the classic therapy, but laser cordectomy and Botulinum toxin injection in the laryngeal muscles are alternatives
Algorithmic Bayesian Persuasion
Persuasion, defined as the act of exploiting an informational advantage in
order to effect the decisions of others, is ubiquitous. Indeed, persuasive
communication has been estimated to account for almost a third of all economic
activity in the US. This paper examines persuasion through a computational
lens, focusing on what is perhaps the most basic and fundamental model in this
space: the celebrated Bayesian persuasion model of Kamenica and Gentzkow. Here
there are two players, a sender and a receiver. The receiver must take one of a
number of actions with a-priori unknown payoff, and the sender has access to
additional information regarding the payoffs. The sender can commit to
revealing a noisy signal regarding the realization of the payoffs of various
actions, and would like to do so as to maximize her own payoff assuming a
perfectly rational receiver.
We examine the sender's optimization task in three of the most natural input
models for this problem, and essentially pin down its computational complexity
in each. When the payoff distributions of the different actions are i.i.d. and
given explicitly, we exhibit a polynomial-time (exact) algorithm, and a
"simple" -approximation algorithm. Our optimal scheme for the i.i.d.
setting involves an analogy to auction theory, and makes use of Border's
characterization of the space of reduced-forms for single-item auctions. When
action payoffs are independent but non-identical with marginal distributions
given explicitly, we show that it is #P-hard to compute the optimal expected
sender utility. Finally, we consider a general (possibly correlated) joint
distribution of action payoffs presented by a black box sampling oracle, and
exhibit a fully polynomial-time approximation scheme (FPTAS) with a bi-criteria
guarantee. We show that this result is the best possible in the black-box model
for information-theoretic reasons
Anharmonicities of giant dipole excitations
The role of anharmonic effects on the excitation of the double giant dipole
resonance is investigated in a simple macroscopic model.Perturbation theory is
used to find energies and wave functions of the anharmonic ascillator.The cross
sections for the electromagnetic excitation of the one- and two-phonon giant
dipole resonances in energetic heavy-ion collisions are then evaluated through
a semiclassical coupled-channel calculation.It is argued that the variations of
the strength of the anharmonic potential should be combined with appropriate
changes in the oscillator frequency,in order to keep the giant dipole resonance
energy consistent with the experimental value.When this is taken into
account,the effects of anharmonicities on the double giant dipole resonance
excitation probabilities are small and cannot account for the well-known
discrepancy between theory and experiment
Fairly Allocating Contiguous Blocks of Indivisible Items
In this paper, we study the classic problem of fairly allocating indivisible
items with the extra feature that the items lie on a line. Our goal is to find
a fair allocation that is contiguous, meaning that the bundle of each agent
forms a contiguous block on the line. While allocations satisfying the
classical fairness notions of proportionality, envy-freeness, and equitability
are not guaranteed to exist even without the contiguity requirement, we show
the existence of contiguous allocations satisfying approximate versions of
these notions that do not degrade as the number of agents or items increases.
We also study the efficiency loss of contiguous allocations due to fairness
constraints.Comment: Appears in the 10th International Symposium on Algorithmic Game
Theory (SAGT), 201
How harmonic is dipole resonance of metal clusters?
We discuss the degree of anharmonicity of dipole plasmon resonances in metal
clusters. We employ the time-dependent variational principle and show that the
relative shift of the second phonon scales as in energy, being
the number of particles. This scaling property coincides with that for nuclear
giant resonances. Contrary to the previous study based on the boson-expansion
method, the deviation from the harmonic limit is found to be almost negligible
for Na clusters, the result being consistent with the recent experimental
observation.Comment: RevTex, 8 page
Proof-theoretic Analysis of Rationality for Strategic Games with Arbitrary Strategy Sets
In the context of strategic games, we provide an axiomatic proof of the
statement Common knowledge of rationality implies that the players will choose
only strategies that survive the iterated elimination of strictly dominated
strategies. Rationality here means playing only strategies one believes to be
best responses. This involves looking at two formal languages. One is
first-order, and is used to formalise optimality conditions, like avoiding
strictly dominated strategies, or playing a best response. The other is a modal
fixpoint language with expressions for optimality, rationality and belief.
Fixpoints are used to form expressions for common belief and for iterated
elimination of non-optimal strategies.Comment: 16 pages, Proc. 11th International Workshop on Computational Logic in
Multi-Agent Systems (CLIMA XI). To appea
Double Giant Dipole Resonance in ^{208}Pb
Double-dipole excitations in ^{208}Pb are analyzed within a microscopic model
explicitly treating 2p2h-excitations. Collective states built from such
2p2h-excitations are shown to appear at about twice the energy of the isovector
giant dipole resonance, in agreement with the experimental findings. The
calculated cross section for Coulomb excitation at relativistic energies cannot
explain simultaneously the measured single-dipole and double-dipole cross
sections, however.Comment: 7 pages, Latex, 5 postscript figure
Anharmonic collective excitation in a solvable model
We apply the time-dependent variational principle, the nuclear field theory,
and the boson expansion method to the Lipkin model to discuss anharmonicities
of collective vibrational excitations. It is shown that all of these approaches
lead to the same anharmonicity to leading order in the number of particles.
Comparison with the exact solution of the Lipkin model shows that these
theories reproduce it quite well.Comment: RevTex, 18 pages, 4 postscript figure
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