65 research outputs found
Antidiarrheal pill in the airway
Pill aspiration depicts an unusual type of foreign body aspiration necessitating a discrete diagnostic and therapeutic approach.1 Some pills may remain intact in the endobronchial tree for many years without causing much harm, whereas others may dissolve2 The clinical outcomes may also vary, from an asymptomatic granuloma to severe, life-threatening airway complications, depending upon the chemical properties of the pill. We report a compelling case of pill aspiration in a healthy patient.
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Agent-based evolving network modeling: a new simulation method for modeling low prevalence infectious diseases
Agent-based network modeling (ABNM) simulates each person at the individual-level as agents of the simulation, and uses network generation algorithms to generate the network of contacts between individuals. ABNM are suitable for simulating individual-level dynamics of infectious diseases, especially for diseases such as HIV that spread through close contacts within intricate contact networks. However, as ABNM simulates a scaled-version of the full population, consisting of all infected and susceptible persons, they are computationally infeasible for studying certain questions in low prevalence diseases such as HIV. We present a new simulation technique, agent-based evolving network modeling (ABENM), which includes a new network generation algorithm, Evolving Contact Network Algorithm (ECNA), for generating scale-free networks. ABENM simulates only infected persons and their immediate contacts at the individual-level as agents of the simulation, and uses the ECNA for generating the contact structures between these individuals. All other susceptible persons are modeled using a compartmental modeling structure. Thus, ABENM has a hybrid agent-based and compartmental modeling structure. The ECNA uses concepts from graph theory for generating scale-free networks. Multiple social networks, including sexual partnership networks and needle sharing networks among injecting drug-users, are known to follow a scale-free network structure. Numerical results comparing ABENM with ABNM estimations for disease trajectories of hypothetical diseases transmitted on scale-free contact networks are promising for application to low prevalence diseases
Unseen Classes at a Later Time? No Problem
Recent progress towards learning from limited supervision has encouraged efforts towards designing models that can recognize novel classes at test time (generalized zero-shot learning or GZSL). GZSL approaches assume knowledge of all classes, with or without labeled data, beforehand. However, practical scenarios demand models that are adaptable and can handle dynamic addition of new seen and unseen classes on the fly (i.e continual generalized zero-shot learning or CGZSL). One solution is to sequentially retrain and reuse conventional GZSL methods, however, such an approach suffers from catastrophic forgetting leading to suboptimal generalization performance. A few recent efforts towards tackling CGZSL have been limited by difference in settings, practicality, data splits and protocols followed - inhibiting fair comparison and a clear direction forward. Motivated from these observations, in this work, we firstly consolidate the different CGZSL setting variants and propose a new Online-CGZSL setting which is more practical and flexible. Secondly, we introduce a unified feature-generative framework for CGZSL that leverages bi-directional incremental alignment to dynamically adapt to addition of new classes, with or without labeled data, that arrive over time in any of these CGZSL settings. Our comprehensive experiments and analysis on five benchmark datasets and comparison with baselines show that our approach consistently outperforms existing methods, especially on the more practical Online setting. © 2022 IEEE
Hypertension management in rural western Kenya: a needs-based health workforce estimation model
Background: Elevated blood pressure is the leading risk for mortality in the world. Task redistribution has been shown
to be efficacious for hypertension management in low- and middle-income countries. However, the workforce
requirements for such a task redistribution strategy are largely unknown. Therefore, we developed a needs-based
workforce estimation model for hypertension management in western Kenya, using need and capacity as inputs.
Methods: Key informant interviews, focus group discussions, a Delphi exercise, and time-motion studies were conducted
among administrative leadership, clinicians, patients, community leaders, and experts in hypertension management.
These results were triangulated to generate the best estimates for the inputs into the health workforce model. The local
hypertension clinical protocol was used to derive a schedule of encounters with different levels of clinician and health
facility staff. A Microsoft Excel-based spreadsheet was developed to enter the inputs and generate the full-time equivalent
workforce requirement estimates over 3 years.
Results: Two different scenarios were modeled: (1) “ramp-up” (increasing growth of patients each year) and (2) “steady
state” (constant rate of patient enrollment each month). The ramp-up scenario estimated cumulative enrollment of
7000 patients by year 3, and an average clinical encounter time of 8.9 min, yielding nurse full-time equivalent
requirements of 4.8, 13.5, and 30.2 in years 1, 2, and 3, respectively. In contrast, the steady-state scenario assumed a
constant monthly enrollment of 100 patients and yielded nurse full-time equivalent requirements of 5.8, 10.5, and 14.3
over the same time period.
Conclusions: A needs-based workforce estimation model yielded health worker full-time equivalent estimates required
for hypertension management in western Kenya. The model is able to provide workforce projections that are useful for
program planning, human resource allocation, and policy formulation. This approach can serve as a benchmark for
chronic disease management programs in low-resource settings worldwideResearch reported in this publication was supported by the Fogarty International
Center of the National Institutes of Health under award number K01 TW 009218-
05
Discrete-Event Simulation and Integer Linear Programming for Constraint-Aware Resource Scheduling
This paper presents a method for scheduling resources in complex systems that integrate humans with diverse hardware and software components, and for studying the impact of resource schedules on system characteristics. The method uses discrete-event simulation and integer linear programming, and relies on detailed models of the system’s processes, specifications of the capabilities of the system’s resources, and constraints on the operations of the system and its resources. As a case study, we examine processes involved in the operation of a hospital emergency department, studying the impact staffing policies have on such key quality measures as patient length of stay (LoS), number of handoffs, staff utilization levels, and cost. Our results suggest that physician and nurse utilization levels for clinical tasks of 70% result in a good balance between LoS and cost. Allowing shift lengths to vary and shifts to overlap increases scheduling flexibility. Clinical experts provided face validation of our results. Our approach improves on the state of the art by enabling using detailed resource and constraint specifications effectively to support analysis and decision making about complex processes in domains that currently rely largely on trial and error and other ad hoc methods
De Sitter Vacua from Heterotic M-Theory
It is shown how metastable de Sitter vacua might arise from heterotic
M-theory. The balancing of its two non-perturbative effects, open membrane
instantons against gaugino condensation on the hidden boundary, which act with
opposing forces on the interval length, is used to stabilize the orbifold
modulus (dilaton) and other moduli. The non-perturbative effects break
supersymmetry spontaneously through F-terms which leads to a positive vacuum
energy density. In contrast to the situation for the weakly coupled heterotic
string, the charged scalar matter fields receive non-vanishing vacuum
expectation values and therefore masses in a phenomenologically relevant
regime. It is important that in order to obtain these de Sitter vacua we are
not relying on exotic effects or fine-tuning of parameters. Vacua with more
realistic supersymmetry breaking scales and gravitino masses are obtained by
breaking the hidden gauge group down to groups of smaller rank. Also
small values for the open membrane instanton Pfaffian are favored in this
respect. Finally we outline how the incorporation of additional flux
superpotentials can be used to stabilize the remaining moduli.Comment: 45 pages, 5 figures, typos correcte
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How Good Science and Stories Can Go Hand-In-Hand
What do you say when you have only a minute to explain to a municipal official why keeping track of the number of bird species found in a park may help make decisions about park management? Talk of significant differences among treatments or testing theory will likely meet with glazed looks. In contrast, sharing the stories of the citizen scientists who have censused the birds year after year makes the information more personal and more salient.
Stories bring conservation science to life. When one hears how Trevor Lloyd Evans, indefatigable director of bird banding at Manomet Center for Conservation Sciences, awoke before dawn every morning, rain or shine, and led his team of volunteer banders in their mist‐netting surveys, as he has done every spring and fall for more than 40 years; how spring migrants arrive earlier than they used to; and how magical the day was when volunteers mist‐netted a Golden‐winged Warbler (Vermivora chrysoptera), a species not captured in over a decade, the significance of the issues, the contributions of science, and possible solutions become much clearer (Manomet Center 2012). We can explain, through Trevor's story, how assessments of ecosystem health are informed by long‐term observations and deep knowledge of natural and human history in particular places.
Here, however, we focus on the complementary roles stories can play, together with science, in advancing conservation science and practice. We assert that conservation interventions that recognize the synergies between science and storytelling may achieve more substantial biological and social outcomes than those that rely on only one or the other. In our work as conservation scientists, we have observed at least 3 types of synergy between stories and science: stories convey the significance of our science (communication), stories can serve as data (scholarship), and stories illustrate how scientific knowledge can illuminate policy choices (translation). We illustrate these synergies with a story from Cabo Pulmo, a national park in Mexico's Baja California Sur.Keywords: Gulf of California, Conservation science, Ecosystem services, Biodiversit
M(atrix) Theory: Matrix Quantum Mechanics as a Fundamental Theory
A self-contained review is given of the matrix model of M-theory. The
introductory part of the review is intended to be accessible to the general
reader. M-theory is an eleven-dimensional quantum theory of gravity which is
believed to underlie all superstring theories. This is the only candidate at
present for a theory of fundamental physics which reconciles gravity and
quantum field theory in a potentially realistic fashion. Evidence for the
existence of M-theory is still only circumstantial---no complete
background-independent formulation of the theory yet exists. Matrix theory was
first developed as a regularized theory of a supersymmetric quantum membrane.
More recently, the theory appeared in a different guise as the discrete
light-cone quantization of M-theory in flat space. These two approaches to
matrix theory are described in detail and compared. It is shown that matrix
theory is a well-defined quantum theory which reduces to a supersymmetric
theory of gravity at low energies. Although the fundamental degrees of freedom
of matrix theory are essentially pointlike, it is shown that higher-dimensional
fluctuating objects (branes) arise through the nonabelian structure of the
matrix degrees of freedom. The problem of formulating matrix theory in a
general space-time background is discussed, and the connections between matrix
theory and other related models are reviewed.Comment: 56 pages, 3 figures, LaTeX, revtex style; v2: references adde
Comments on black holes in bubbling spacetimes
In five-dimensional minimal supergravity, there are spherical black holes
with nontrivial topology outside the horizon which have the same conserved
charges at infinity as the BMPV solution. We show that some of these black
holes have greater entropy than the BMPV solution. These spacetimes are all
asymptotically flat, stationary, and supersymmetric. We also show that there is
a limit in which the black hole shrinks to zero size and the solution becomes a
nonsingular "bubbling" geometry. Thus, these solutions provide explicit
analytic examples of placing black holes inside solitons.Comment: 17 pages, 5 figures; v2: references adde
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