136 research outputs found
Recurrence Relations for Moments of Dual Generalized Order Statistics from Weibull Gamma Distribution and Its Characterizations
In this paper, we establish explicit forms and new recurrence relations satisfied by the single and product moments of dual generalized order statistics from Weibull gamma distribution (WGD). The results include as particular cases the relations for moments of reversed order statistics and lower records.We present characterizations ofWGD based on (i) recurrence relation for single moments, (ii) truncated moments of certain function of the variable and (iii) hazrad function
Conservation of statistical results under the reduction of pair-contact interactions to solvation interactions
We show that the hydrophobicity of sequences is the leading term in
Miyazawa-Jernigan interactions. Being the source of additive (solvation) terms
in pair-contact interactions, they were used to reduce the energy parameters
while resulting in a clear vector manipulation of energy. The reduced
(additive) potential performs considerably successful in predicting the
statistical properties of arbitrary structures. The evaluated designabilities
of the structures by both models are highly correlated. Suggesting
geometrically non-degenerate vectors (structures) as protein-like structures,
the additive model is a powerful tool for protein design. Moreover, a crossing
point in the log-linear diagram of designability-ranking shows that about 1/e
of the structures have designabilities above the average, independent on the
used model.Comment: 17 pages and 10 figure
Iteration Complexity of Randomized Primal-Dual Methods for Convex-Concave Saddle Point Problems
In this paper we propose a class of randomized primal-dual methods to contend
with large-scale saddle point problems defined by a convex-concave function
. We analyze the convergence rate of the
proposed method under the settings of mere convexity and strong convexity in
-variable. In particular, assuming is
Lipschitz and is coordinate-wise Lipschitz for
any fixed , the ergodic sequence generated by the algorithm achieves the
convergence rate of in a suitable error metric where
denotes the number of coordinates for the primal variable. Furthermore,
assuming that is uniformly strongly convex for any ,
and that is linear in , the scheme displays convergence rate
of . We implemented the proposed algorithmic framework to
solve kernel matrix learning problem, and tested it against other
state-of-the-art solvers
Development and validation of a pragmatic natural language processing approach to identifying falls in older adults in the emergency department
BACKGROUND:
Falls among older adults are both a common reason for presentation to the emergency department, and a major source of morbidity and mortality. It is critical to identify fall patients quickly and reliably during, and immediately after, emergency department encounters in order to deliver appropriate care and referrals. Unfortunately, falls are difficult to identify without manual chart review, a time intensive process infeasible for many applications including surveillance and quality reporting. Here we describe a pragmatic NLP approach to automating fall identification.
METHODS:
In this single center retrospective review, 500 emergency department provider notes from older adult patients (age 65 and older) were randomly selected for analysis. A simple, rules-based NLP algorithm for fall identification was developed and evaluated on a development set of 1084 notes, then compared with identification by consensus of trained abstractors blinded to NLP results.
RESULTS:
The NLP pipeline demonstrated a recall (sensitivity) of 95.8%, specificity of 97.4%, precision of 92.0%, and F1 score of 0.939 for identifying fall events within emergency physician visit notes, as compared to gold standard manual abstraction by human coders.
CONCLUSIONS:
Our pragmatic NLP algorithm was able to identify falls in ED notes with excellent precision and recall, comparable to that of more labor-intensive manual abstraction. This finding offers promise not just for improving research methods, but as a potential for identifying patients for targeted interventions, quality measure development and epidemiologic surveillance
Finite-time quantum Stirling heat engine
We study the thermodynamic performance of a finite-time non-regenerative quantum Stirling-like cycle used as a heat engine. We consider specifically the case in which the working substance (WS) is a two-level system (TLS). The Stirling cycle is made of two isochoric transformations separated by a compression and an expansion stroke during which the WS is in contact with a thermal reservoir. To describe these two strokes we derive a non-Markovian master equation which allows to study the real-time dynamics of a driven open quantum system with arbitrary fast driving. Following the real-time dynamics of the WS using this master equation, the endpoints of the isotherms can deviate from the equilibrium thermal states. The role of this deviation in the performance of the heat engine is addressed. We found that the finite-time dynamics and thermodynamics of the cycle depend non-trivially on the different time scales at play. In particular, driving the WS at a time scale comparable to the resonance time of the bath enhances the performance of the cycle and allows for an efficiency higher than the efficiency of the quasistatic cycle, but still below the Carnot bound. However, by adding thermalization of the WS with the baths at the end of compression/expansion processes one recovers the conventional scenario in which efficiency decreases by speeding up the processes. In addition, the performance of the cycle is dependent on the compression/expansion speeds asymmetrically, which suggests new freedom in optimizing quantum heat engines. The maximum output power and the maximum efficiency are obtained almost simultaneously when the real-time endpoints of the compression/expansion processes are considered instead of the equilibrium thermal endpoint states. However, the net extractable work always declines by speeding up the drive.Peer reviewe
Geometrically Reduced Number of Protein Ground State Candidates
Geometrical properties of protein ground states are studied using an
algebraic approach. It is shown that independent from inter-monomer
interactions, the collection of ground state candidates for any folded protein
is unexpectedly small: For the case of a two-parameter Hydrophobic-Polar
lattice model for -mers, the number of these candidates grows only as .
Moreover, the space of the interaction parameters of the model breaks up into
well-defined domains, each corresponding to one ground state candidate, which
are separated by sharp boundaries. In addition, by exact enumeration, we show
there are some sequences which have one absolute unique native state. These
absolute ground states have perfect stability against change of inter-monomer
interaction potential.Comment: 9 page, 4 ps figures are include
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