513 research outputs found
Effects of Mass Media and Cultural Drift in a Model for Social Influence
In the context of an extension of Axelrod's model for social influence, we
study the interplay and competition between the cultural drift, represented as
random perturbations, and mass media, introduced by means of an external
homogeneous field. Unlike previous studies [J. C. Gonz\'alez-Avella {\it et
al}, Phys. Rev. E {\bf 72}, 065102(R) (2005)], the mass media coupling proposed
here is capable of affecting the cultural traits of any individual in the
society, including those who do not share any features with the external
message. A noise-driven transition is found: for large noise rates, both the
ordered (culturally polarized) phase and the disordered (culturally fragmented)
phase are observed, while, for lower noise rates, the ordered phase prevails.
In the former case, the external field is found to induce cultural ordering, a
behavior opposite to that reported in previous studies using a different
prescription for the mass media interaction. We compare the predictions of this
model to statistical data measuring the impact of a mass media vasectomy
promotion campaign in Brazil.Comment: 10 pages, 3 figures; minor changes; added references. To appear in
IJMP
Exact time-reversal focusing of acoustic and quantum excitations in open cavities: The perfect inverse filter
The time-reversal mirror (TRM) prescribes the reverse playback of a signal to
focalize an acoustic excitation as a Loschmidt echo. In the quantum domain, the
perfect inverse filter (PIF) processes this signal to ensure an exact reversion
provided that the excitation originated outside the cavity delimited by the
transducers. We show that PIF takes a simple form when the initial excitation
is created inside this cavity. This also applies to the acoustical case, where
it corrects the TRM and improves the design of an acoustic bazooka. We solve an
open chaotic cavity modeling a quantum bazooka and a simple model for a
Helmholtz resonator, showing that the PIF becomes decisive to compensate the
group velocities involved in a highly localized excitation and to achieve
subwavelength resolution.Comment: 6 pages, 2 figure
Enhancement of Stochastic Resonance in distributed systems due to a selective coupling
Recent massive numerical simulations have shown that the response of a
"stochastic resonator" is enhanced as a consequence of spatial coupling.
Similar results have been analytically obtained in a reaction-diffusion model,
using "nonequilibrium potential" techniques. We now consider a field-dependent
diffusivity and show that the "selectivity" of the coupling is more efficient
for achieving stochastic-resonance enhancement than its overall value in the
constant-diffusivity case.Comment: 10 pgs (RevTex), 4 figures, submitted to Phys.Rev.Let
Toward An Identity for the Field of Doctoral Education in Health Sciences
The Association of Doctoral Programs in Health Sciences (ADPHS) was informally established in November 2019, officially incorporated in August 2021, and is currently a 501(c)(3) non-profit organization comprised of the directors of member doctoral programs of health sciences. The ADPHS grew from informal discussions among program directors who agreed that a major problem in the field of doctoral education in health sciences was the lack of a clearly defined and easily articulable identity. The discussions led to the drafting of an informal and nonscientific survey used to help clarify the current health sciences education environment, relevant emerging trends, and the educational philosophies adopted by the directors of health sciences doctoral programs nationally. The results of the survey and follow-up discussions revealed a strong consensus among program directors that the field of doctorate education in health sciences is uniformly characterized by its interdisciplinary nature. In this position paper, we provide the rationale for the formal position of the ADPHS that the identity of the field of doctoral education in health sciences is based on its interdisciplinary approach to education
ADJOINT-ASSISTED INVERSION FOR SHALLOW WATER ENVIRONMENT PARAMETERS
The adjoint of a forward model can back-propagate mismatch between observations and their predictions and produce the corrections to the forward model inputs that caused the mismatch. As an example of this process, the adjoint of a parabolic equation propagation model is used to invert errors in pressure predictions at a receiver for sound speed perturbations due to internal tides
Spatial diversity in passive time reversal communications
A time reversal mirror exploits spatial diversity to achieve spatial and temporal focusing, a useful property for communications in an environment with significant multipath. Taking advantage of spatial diversity involves using a number of receivers distributed in space. This paper presents the impact of spatial diversity in passive time reversal communications between a probe source (PS) and a vertical receive array using at-sea experimental data, while the PS is either fixed or moving at about 4 knots. The performance of two different approaches is compared in terms of output signal-to-noise ratio versus the number of receiver elements: (1) time reversal alone and (2) time reversal combined with adaptive channel equalization. The time-varying channel response due to source motion requires an adaptive channel equalizer such that approach (2) outperforms approach (1) by up to 13 dB as compared to 5 dB for a fixed source case. Experimental results around 3 kHz with a 1 kHz bandwidth illustrate that as few as two or three receivers (i.e., 2 or 4 in array aperture) can provide reasonable performance at ranges of 4.2 and 10 km in 118 in deep water. (c) 2006 Acoustical Society of America
Exact expression for the diffusion propagator in a family of time-dependent anharmonic potentials
We have obtained the exact expression of the diffusion propagator in the
time-dependent anharmonic potential . The
underlying Euclidean metric of the problem allows us to obtain analytical
solutions for a whole family of the elastic parameter a(t), exploiting the
relation between the path integral representation of the short time propagator
and the modified Bessel functions. We have also analyzed the conditions for the
appearance of a non-zero flow of particles through the infinite barrier located
at the origin (b<0).Comment: RevTex, 19 pgs. Accepted in Physical Review
Advertising and irreversible opinion spreading in complex social networks
Irreversible opinion spreading phenomena are studied on small-world and
scale-free networks by means of the magnetic Eden model, a nonequilibrium
kinetic model for the growth of binary mixtures in contact with a thermal bath.
In this model, the opinion of an individual is affected by those of their
acquaintances, but opinion changes (analogous to spin flips in an Ising-like
model) are not allowed. We focus on the influence of advertising, which is
represented by external magnetic fields. The interplay and competition between
temperature and fields lead to order-disorder transitions, which are found to
also depend on the link density and the topology of the complex network
substrate. The effects of advertising campaigns with variable duration, as well
as the best cost-effective strategies to achieve consensus within different
scenarios, are also discussed.Comment: 20 pages, 11 figures. To appear in IJMP
Computerized clinical documentation system in the pediatric intensive care unit
BACKGROUND: To determine whether a computerized clinical documentation system (CDS): 1) decreased time spent charting and increased time spent in patient care; 2) decreased medication errors; 3) improved clinical decision making; 4) improved quality of documentation; and/or 5) improved shift to shift nursing continuity. METHODS: Before and after implementation of CDS, a time study involving nursing care, medication delivery, and normalization of serum calcium and potassium values was performed. In addition, an evaluation of completeness of documentation and a clinician survey of shift to shift reporting were also completed. This was a modified one group, pretest-posttest design. RESULTS: With the CDS there was: improved legibility and completeness of documentation, data with better accessibility and accuracy, no change in time spent in direct patient care or charting by nursing staff. Incidental observations from the study included improved management functions of our nurse manager; improved JCAHO documentation compliance; timely access to clinical data (labs, vitals, etc); a decrease in time and resource use for audits; improved reimbursement because of the ability to reconstruct lost charts; limited human data entry by automatic data logging; eliminated costs of printing forms. CDS cost was reasonable. CONCLUSIONS: When compared to a paper chart, the CDS provided a more legible, compete, and accessible patient record without affecting time spent in direct patient care. The availability of the CDS improved shift to shift reporting. Other observations showed that the CDS improved management capabilities; helped physicians deliver care; improved reimbursement; limited data entry errors; and reduced costs
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