285 research outputs found
Dealing with uncertainty in agent-based models for short-term predictions
Agent-based models (ABMs) are gaining traction as one of the most powerful modelling tools within the social sciences. They are particularly suited to simulating complex systems. Despite many methodological advances within ABM, one of the major drawbacks is their inability to incorporate real-time data to make accurate short-term predictions. This paper presents an approach that allows ABMs to be dynamically optimized. Through a combination of parameter calibration and data assimilation (DA), the accuracy of model-based predictions using ABM in real time is increased. We use the exemplar of a bus route system to explore these methods. The bus route ABMs developed in this research are examples of ABMs that can be dynamically optimized by a combination of parameter calibration and DA. The proposed model and framework is a novel and transferable approach that can be used in any passenger information system, or in an intelligent transport systems to provide forecasts of bus locations and arrival times
The second law, Maxwell's daemon and work derivable from quantum heat engines
With a class of quantum heat engines which consists of two-energy-eigenstate
systems undergoing, respectively, quantum adiabatic processes and energy
exchanges with heat baths at different stages of a cycle, we are able to
clarify some important aspects of the second law of thermodynamics. The quantum
heat engines also offer a practical way, as an alternative to Szilard's engine,
to physically realise Maxwell's daemon. While respecting the second law on the
average, they are also capable of extracting more work from the heat baths than
is otherwise possible in thermal equilibrium
Sub-kHz lasing of a CaF_2 Whispering Gallery Mode Resonator Stabilized Fiber Ring Laser
We utilize a high quality calcium fluoride whispering-gallery-mode resonator
to stabilize a simple erbium doped fiber ring laser with an emission frequency
of 196 THz (wavelenght 1530 nm) to a linewidth below 650 Hz. This corresponds
to a relative stability of 3.3 x 10^(-12) over 16 \mus. In order to
characterize the linewidth we use two identical self-built lasers and a
commercial laser to determine the individual lasing linewidth via the
three-cornered hat method.Comment: 4 pages, 3 figure
Let's listen: the voices of ethnic villagers in identifying host-tourist interaction issues in the Central Highlands, Vietnam
Host-tourist interaction is a core attraction of ethnic tourism. Yet both parties may confront challenges in such interactions because of different cultural backgrounds. This study aims to investigate host-tourist interaction issues in Vietnam’s Central Highlands by adopting a qualitative approach wherein 31 semi-structured interviews were conducted with villagers. Results find that villagers interacted with domestic tourists mostly in private houses, tourist attractions and facilities, and on tours. In such settings, the content of interactions varied from low to high intensity. Derived from the Coordinated Management of Meaning (CMM) theory [Pearce, W. B., & Cronen, V. E. (1980). Communication action and meaning. Praeger], verbal (language) and non-verbal behaviour and cultural patterns were the greatest interaction difficulties. While interaction difficulties occurred across different settings, higher intensity interactions resulted in more positive outcomes. This study enriches the existing knowledge on interaction between ethnic hosts and domestic tourists in the intra-national context. The interpretive theoretical and methodological utility of CMM provided insight into interaction difficulties, and opportunities to facilitate positive interactions in ethnic tourism development. Further implications for villagers, tourists, local policymakers, and tour operators were suggested to build long-term sustainability of the host-tourist relationship in the Central Highlands
Fluid Flows of Mixed Regimes in Porous Media
In porous media, there are three known regimes of fluid flows, namely,
pre-Darcy, Darcy and post-Darcy. Because of their different natures, these are
usually treated separately in literature. To study complex flows when all three
regimes may be present in different portions of a same domain, we use a single
equation of motion to unify them. Several scenarios and models are then
considered for slightly compressible fluids. A nonlinear parabolic equation for
the pressure is derived, which is degenerate when the pressure gradient is
either small or large. We estimate the pressure and its gradient for all time
in terms of initial and boundary data. We also obtain their particular bounds
for large time which depend on the asymptotic behavior of the boundary data but
not on the initial one. Moreover, the continuous dependence of the solutions on
initial and boundary data, and the structural stability for the equation are
established.Comment: 33 page
Quantum hypercomputation based on the dynamical algebra su(1,1)
An adaptation of Kieu's hypercomputational quantum algorithm (KHQA) is
presented. The method that was used was to replace the Weyl-Heisenberg algebra
by other dynamical algebra of low dimension that admits infinite-dimensional
irreducible representations with naturally defined generalized coherent states.
We have selected the Lie algebra , due to that this algebra
posses the necessary characteristics for to realize the hypercomputation and
also due to that such algebra has been identified as the dynamical algebra
associated to many relatively simple quantum systems. In addition to an
algebraic adaptation of KHQA over the algebra , we
presented an adaptations of KHQA over some concrete physical referents: the
infinite square well, the infinite cylindrical well, the perturbed infinite
cylindrical well, the P{\"o}sch-Teller potentials, the Holstein-Primakoff
system, and the Laguerre oscillator. We conclude that it is possible to have
many physical systems within condensed matter and quantum optics on which it is
possible to consider an implementation of KHQA.Comment: 25 pages, 1 figure, conclusions rewritten, typing and language errors
corrected and latex format changed minor changes elsewhere and
Large energy mode locking of an erbium-doped fiber laser with atomic layer graphene
We report on large energy pulse generation in an erbium-doped fiber laser
passively mode-locked with atomic layer graphene. Stable mode locked pulses
with single pulse energy up to 7.3 nJ and pulse width of 415 fs have been
directly generated from the laser. Our results show that atomic layer graphene
could be a promising saturable absorber for large energy mode locking.Comment: 14 pages 4 figure
Whispering gallery mode resonator based ultra-narrow linewidth external cavity semiconductor laser
We demonstrate a miniature self-injection locked DFB laser using resonant
optical feedback from a high-Q crystalline whispering gallery mode resonator.
The linewidth reduction factor is greater than 10,000, with resultant
instantaneous linewidth less than 200 Hz. The minimal value of the Allan
deviation for the laser frequency stability is 3x10^(-12) at the integration
time of 20 us. The laser possesses excellent spectral purity and good long term
stability.Comment: To be published in Optics Letter
Development of a Micro-credential Curriculum: The Interprofessional Dementia Caregiving Telehealth Community Practicum Badge
Purpose: Informal dementia caregiving by family caregivers is a crucial component of the care provided to people living with dementia (PLwD). The numbers of these family caregivers are rapidly increasing at a time, when in the U.S., the availability of formal caregivers is decreasing. Currently, health professional training focuses on providing care to PLwD and not necessarily addressing the caregiver’s needs, and this training takes place within professional silos and not interprofessionally. This study sought to address this issue by: 1) examining the current state of interprofessional dementia caregiving trainings in the US; and 2) developing a micro-credential curriculum called interprofessional dementia caregiving telehealth community practicum badge suitable for health profession students in order to meet the needs of dementia caregivers in Wisconsin. Methods: A four-phase-embedded approach was used. In the first phase, a scoping review on the current state of interprofessional education regarding caregivers of PLwD was conducted. Next, a team comprised of 6 faculty and staff with expertise in dementia care and caregiving, 2 dementia care specialists (DCS), and 2 family caregivers provided their expertise and input into developing the components of a micro-credential badge. These components and details were then assessed/revised based on interviews with 11 additional family caregivers, DCSs, and community leaders. Finally, the micro-credential interprofessional dementia caregiving curriculum was developed. Results: The micro-credential curriculum was named the Interprofessional Dementia Caregiving Telehealth Community Practicum Badge. The badge requires that an interprofessional team of students to: 1) complete five self-directed modules; 2) conduct initial virtual caregiver home visit to assess needs; 3) hold a virtual meeting with an Aging Disability Resource Center (ADRC) specialist to acquire the resources; 4) develop a customized Caregiver Health and Wellness Resource Packet; 5) hold a second/final virtual home visit to present the packet to the caregiver; 6) conduct a debrief session with all involved parties; and 7) finalize/submit the Packet along with reflection as a Capstone Project. Conclusion The micro-credential badge curriculum was piloted in the spring of 2022 while incorporating findings from this study. The completion of the interprofessional dementia caregiving badge counts towards the UW IPE Path of Distinctio
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