5,021 research outputs found
THE PACIFIC RIM BEEF TRADE: IMPACTS OF LIFTING FOOT-AND-MOUTH DISEASE TRADE BARRIERS
International Relations/Trade,
Experiences With Peace Corps’ Third Goal: Perspectives Of Peace Corps Mali Volunteers
When asked what the best part of their service was, the large majority of Peace Corps Volunteers will light up as they describe a cross-cultural experience or relationship. Peace Corps Volunteers want to share these sentiments with Americans. I conducted a qualitative case study by interviewing three fellow Peace Corps Volunteers and evaluating 35 survey responses, in order to explore Peace Corps Volunteers’ perceptions of Peace Corps’ Third Goal- to share a host country culture with Americans. The interviews were transcribed and then compared and contrasted. From the interviews and survey findings, it has been found that the Peace Corps Mali training program and interactions with Peace Corps Staff gives the impression that Goal 3 is not as important to meet as Goal 1- skills exchange and project development; Volunteers are not trained on techniques to share their experiences responsibly; Volunteers do not consider cultural exchanges as satisfying “work” due to its perceived, abstract nature in measuring the outcomes; and that the frustrations related to Goal 3 are also contributing to Volunteers carrying out unsustainable projects. It is concluded that the implementation of the recommendations of this study would put an action to Peace Corps Director Aaron William’s words of Goal 3 as one of his top priorities, showing Volunteers in the best way that Peace Corps believes all their goals carry equal weight of importance. Additionally, the lack in promotion of the importance of Goal 3 does not start in Peace Corps training, it comes from the culture of “Development” and American values, leaving Volunteers at a loss for how to meet Goal 3 successfully
Three-body recombination of ultracold Bose gases using the truncated Wigner method
We apply the truncated Wigner method to the process of three-body
recombination in ultracold Bose gases. We find that within the validity regime
of the Wigner truncation for two-body scattering, three-body recombination can
be treated using a set of coupled stochastic differential equations that
include diffusion terms, and can be simulated using known numerical methods. As
an example we investigate the behaviour of a simple homogeneous Bose gas.Comment: Replaced paper same as original; correction to author list on
cond-mat mad
Long delay times in reaction rates increase intrinsic fluctuations
In spatially distributed cellular systems, it is often convenient to
represent complicated auxiliary pathways and spatial transport by time-delayed
reaction rates. Furthermore, many of the reactants appear in low numbers
necessitating a probabilistic description. The coupling of delayed rates with
stochastic dynamics leads to a probability conservation equation characterizing
a non-Markovian process. A systematic approximation is derived that
incorporates the effect of delayed rates on the characterization of molecular
noise, valid in the limit of long delay time. By way of a simple example, we
show that delayed reaction dynamics can only increase intrinsic fluctuations
about the steady-state. The method is general enough to accommodate nonlinear
transition rates, allowing characterization of fluctuations around a
delay-induced limit cycle.Comment: 8 pages, 3 figures, to be published in Physical Review
Derivation of quantum work equalities using quantum Feynman-Kac formula
On the basis of a quantum mechanical analogue of the famous Feynman-Kac
formula and the Kolmogorov picture, we present a novel method to derive
nonequilibrium work equalities for isolated quantum systems, which include the
Jarzynski equality and Bochkov-Kuzovlev equality. Compared with previous
methods in the literature, our method shows higher similarity in form to that
deriving the classical fluctuation relations, which would give important
insight when exploring new quantum fluctuation relations.Comment: 5 page
Predicting rare events in chemical reactions: application to skin cell proliferation
In a well-stirred system undergoing chemical reactions, fluctuations in the
reaction propensities are approximately captured by the corresponding chemical
Langevin equation. Within this context, we discuss in this work how the Kramers
escape theory can be used to predict rare events in chemical reactions. As an
example, we apply our approach to a recently proposed model on cell
proliferation with relevance to skin cancer [P.B. Warren, Phys. Rev. E {\bf
80}, 030903 (2009)]. In particular, we provide an analytical explanation for
the form of the exponential exponent observed in the onset rate of uncontrolled
cell proliferation.Comment: New materials and references added. To appear in Physical Review
Nonnormal amplification in random balanced neuronal networks
In dynamical models of cortical networks, the recurrent connectivity can
amplify the input given to the network in two distinct ways. One is induced by
the presence of near-critical eigenvalues in the connectivity matrix W,
producing large but slow activity fluctuations along the corresponding
eigenvectors (dynamical slowing). The other relies on W being nonnormal, which
allows the network activity to make large but fast excursions along specific
directions. Here we investigate the tradeoff between nonnormal amplification
and dynamical slowing in the spontaneous activity of large random neuronal
networks composed of excitatory and inhibitory neurons. We use a Schur
decomposition of W to separate the two amplification mechanisms. Assuming
linear stochastic dynamics, we derive an exact expression for the expected
amount of purely nonnormal amplification. We find that amplification is very
limited if dynamical slowing must be kept weak. We conclude that, to achieve
strong transient amplification with little slowing, the connectivity must be
structured. We show that unidirectional connections between neurons of the same
type together with reciprocal connections between neurons of different types,
allow for amplification already in the fast dynamical regime. Finally, our
results also shed light on the differences between balanced networks in which
inhibition exactly cancels excitation, and those where inhibition dominates.Comment: 13 pages, 7 figure
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