3,235 research outputs found
Adiabatic theorem for non-hermitian time-dependent open systems
In the conventional quantum mechanics (i.e., hermitian QM) the adia- batic
theorem for systems subjected to time periodic fields holds only for bound
systems and not for open ones (where ionization and dissociation take place)
[D. W. Hone, R. Ketzmerik, and W. Kohn, Phys. Rev. A 56, 4045 (1997)]. Here
with the help of the (t,t') formalism combined with the complex scaling method
we derive an adiabatic theorem for open systems and provide an analytical
criteria for the validity of the adiabatic limit. The use of the complex
scaling transformation plays a key role in our derivation. As a numerical
example we apply the adiabatic theorem we derived to a 1D model Hamiltonian of
Xe atom which interacts with strong, monochromatic sine-square laser pulses. We
show that the gener- ation of odd-order harmonics and the absence of
hyper-Raman lines, even when the pulses are extremely short, can be explained
with the help of the adiabatic theorem we derived
From Health Decisions to Performance: The Network Effect
This study uses a simulation as a vehicle for social networks research application. Eighty five companies were created as partof a simulated healthcare industry. Our results suggest that companies positioning themselves at pivotal points within thenetwork outperform companies that do not. The findings show the applicability of network theory and the use of simulationsin applied research on healthcare decision-making
On Interactive Proofs of Proximity with Proof-Oblivious Queries
Interactive proofs of proximity (IPPs) offer ultra-fast approximate verification of assertions regarding their input, where ultra-fast means that only a small portion of the input is read and approximate verification is analogous to the notion of approximate decision that underlies property testing. Specifically, in an IPP, the prover can make the verifier accept each input in the property, but cannot fool the verifier into accepting an input that is far from the property (except for with small probability).
The verifier in an IPP system engages in two very different types of activities: interacting with an untrusted prover, and querying its input. The definition allows for arbitrary coordination between these two activities, but keeping them separate is both conceptually interesting and necessary for important applications such as addressing temporal considerations (i.e., at what time is each of the services available) and facilitating the construction of zero-knowledge schemes. In this work we embark on a systematic study of IPPs with proof-oblivious queries, where the queries should not be affected by the interaction with the prover. We assign the query and interaction activities to separate modules, and consider different limitations on their coordination.
The most strict limitation requires these activities to be totally isolated from one another; they just feed their views to a separate deciding module. We show that such systems can be efficiently emulated by standard testers.
Going to the other extreme, we only disallow information to flow from the interacting module to the querying module, but allow free information flow in the other direction. We show that extremely efficient one-round (i.e., two-message) systems of such type can be used to verify properties that are extremely hard to test (without the help of a prover). That is, the complexity of verifying can be polylogarithmic in the complexity of testing. This stands in contrast the MAPs (viewed as 1/2-round systems) in which proof-oblivious queries are as limited as our isolated model.
Our focus is on an intermediate model that allows shared randomness between the querying and interacting modules but no information flow between them. In this case we show that 1-round systems are efficiently emulated by standard testers but 3/2-round systems of extremely low complexity exist for properties that are extremely hard to test. One additional result about this model is that it can efficiently emulate any IPP for any property of low-degree polynomials
Case Presentation for Suprascapular Neuropathy
CASE HISTORY: The patient is an 18-year-old female collegiate volleyball player who has suffered progressive shoulder pain in her right shoulder. She states that the pain has progressively gotten worse over the past 3-4 years. The sharp pain began when she would raise her right arm above 90 degrees when hitting an overhand serve. Over time, the pain progressed and became noticeable in additional movements. The patient had noted significant weakness in both her right arm and right shoulder. The patient states when she sleeps on her right arm/shoulder she wakes up in severe pain. She has tried sleeping with the right elbow in extension which has helped in alleviating the pain. PHYSICAL EXAM: The patient’s vital signs were all within normal ranges. A physical exam was performed and identified pain with Hawkins-Kennedy and empty can. Manual muscle testing demonstrated infraspinatus (2/5) and supraspinatus (3/5) weakness. Upper Quarter Y Balance Test revealed right and left composite scores of 85.7 and 96.1, respectively. DIFFERENTIAL DIAGNOSES: Suprascapular nerve palsy; Ulnar nerve palsy; Infraspinatus atrophy; Subacromial impingement syndrome; and rotator cuff injury. TESTS & RESULTS: An X-ray for the right arm and shoulder was also preformed which did not show any pathologies. The patient had a magnetic resonance imaging (MRI) of the right arm and shoulder revealing two lesions in the head of the humerus. An MRI of the cervical spine without contrast was preformed and revealed a mild disk bulge at C5 and C6 with no significant Neural Foraminal Stenosis (NF) narrowing. There was straightening and very slight reversal of the normal cervical lordosis. A nerve conduction study was performed and identified a right sided suprascapular neuropathy at the spinoglenoid notch with significant motor axon loss. Lastly, electrophysiologic testing was done which identified right sided ulnar neuropathy. FINAL DIAGNOSIS: Right sided suprascapular neuropathy at the spinoglenoid notch. Right sided ulnar neuropathy. DISCUSSION: Suprascapular neuropathy is a very uncommon cause for shoulder pain and is often times misdiagnosed. Frequently the diagnosis of suprascapular neuropathy is mistaken for subacromial impingement syndrome, rotator cuff injuries, etc. Common signs and symptoms of suprascapular neuropathy are pain and weakness in the shoulder, atrophy, and often burning and aching. Suprascapular neuropathy is reported to only be found in 0.4% of patients with shoulder pain. The compression of the suprascapular nerve at the spinoglenoid notch is often due to repetitive use and space-occupying lesions. Athletes that perform sports like tennis, weight-lifting, and volleyball are more likely to experience a suprascapular neuropathy injury. OUTCOME OF THE CASE: The patient has been diagnosed with suprascapular neuropathy caused by compression of the suprascapular nerve at the spinoglenoid notch. This patient has been prescribed a rehabilitation program involving the throwers ten to strengthen her rotator cuff muscles along with improving her scapular and glenohumeral stabilization and proprioception. The athlete is participating in normal practice and play and has been told to take over the counter anti-inflammatory medications such as ibuprofen, as needed. RETURN TO ACTIVITY AND FURTHER FOLLOW-UP: The patient is to remain in normal practice and play and continue her basic rehabilitation program. She has been referred to a surgical doctor and has been asked to seek a surgical consultation in the future
Efficient Quantum Polar Coding
Polar coding, introduced 2008 by Arikan, is the first (very) efficiently
encodable and decodable coding scheme whose information transmission rate
provably achieves the Shannon bound for classical discrete memoryless channels
in the asymptotic limit of large block sizes. Here we study the use of polar
codes for the transmission of quantum information. Focusing on the case of
qubit Pauli channels and qubit erasure channels, we use classical polar codes
to construct a coding scheme which, using some pre-shared entanglement,
asymptotically achieves a net transmission rate equal to the coherent
information using efficient encoding and decoding operations and code
construction. Furthermore, for channels with sufficiently low noise level, we
demonstrate that the rate of preshared entanglement required is zero.Comment: v1: 15 pages, 4 figures. v2: 5+3 pages, 3 figures; argumentation
simplified and improve
Entropy, Optimization and Counting
In this paper we study the problem of computing max-entropy distributions
over a discrete set of objects subject to observed marginals. Interest in such
distributions arises due to their applicability in areas such as statistical
physics, economics, biology, information theory, machine learning,
combinatorics and, more recently, approximation algorithms. A key difficulty in
computing max-entropy distributions has been to show that they have
polynomially-sized descriptions. We show that such descriptions exist under
general conditions. Subsequently, we show how algorithms for (approximately)
counting the underlying discrete set can be translated into efficient
algorithms to (approximately) compute max-entropy distributions. In the reverse
direction, we show how access to algorithms that compute max-entropy
distributions can be used to count, which establishes an equivalence between
counting and computing max-entropy distributions
Multi-Modal Motion Planning Using Composite Pose Graph Optimization
In this paper, we present a motion planning framework for multi-modal vehicle
dynamics. Our proposed algorithm employs transcription of the optimization
objective function, vehicle dynamics, and state and control constraints into
sparse factor graphs, which -- combined with mode transition constraints --
constitute a composite pose graph. By formulating the multi-modal motion
planning problem in composite pose graph form, we enable utilization of
efficient techniques for optimization on sparse graphs, such as those widely
applied in dual estimation problems, e.g., simultaneous localization and
mapping (SLAM). The resulting motion planning algorithm optimizes the
multi-modal trajectory, including the location of mode transitions, and is
guided by the pose graph optimization process to eliminate unnecessary
transitions, enabling efficient discovery of optimized mode sequences from
rough initial guesses. We demonstrate multi-modal trajectory optimization in
both simulation and real-world experiments for vehicles with various dynamics
models, such as an airplane with taxi and flight modes, and a vertical take-off
and landing (VTOL) fixed-wing aircraft that transitions between hover and
horizontal flight modes.Comment: 7 pages, 6 figures, to be included in proceedings of IEEE
International Conference on Robotics and Automation 202
Conformal Risk Control
We extend conformal prediction to control the expected value of any monotone
loss function. The algorithm generalizes split conformal prediction together
with its coverage guarantee. Like conformal prediction, the conformal risk
control procedure is tight up to an factor. Worked examples
from computer vision and natural language processing demonstrate the usage of
our algorithm to bound the false negative rate, graph distance, and token-level
F1-score.Comment: Code available at https://github.com/aangelopoulos/conformal-ris
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