3,341 research outputs found
Exploring the Time to Intervene with a Reactive Mass Vaccination Campaign in Measles Epidemics.
The current WHO policy during measles outbreaks focuses on case management rather than reactive vaccination campaigns in urban areas of resource-poor countries having low vaccine coverage. Vaccination campaigns may be costly, or not timely enough to impact significantly on morbidity and mortality. We explored the time available for intervention during two recent epidemics. Our analysis suggests that the spread of measles in African urban settings may not be as fast as expected. Examining measles epidemic spread in Kinshasa (DRC), and Niamey (Niger) reveals a progression of smaller epidemics. Intervening with a mass campaign or in areas where cases have not yet been reported could slow the epidemic spread. The results of this preliminary analysis illustrate the importance of revisiting outbreak response plans
Try it on: Voice, concordancing and text-matching in doctoral writing
Appropriate use and acknowledgement of sources continues to be a central concern of academic integrity. A major challenge for research students in using sources is the development of a confident authorial voice that matches disciplinary expectations in language use, yet manages to do so without plagiarising through inappropriate text- matching or recycling of language. This is a daunting challenge for all research writers, particularly for English as an Additional Language (EAL) researchers who are still grappling with English grammar and syntax. In order to develop novice research writers' understanding of acceptable use of sources and mastery of disciplinary language, we have developed a process called "Try it on" that uses concordancing software alongside text-matching software (Turnitin). Here we present textual analyses of two cases using this process: in one, the student's percentage of matches decreased as he developed his authorial voice; in the second, the percentage of matches increased as the student's language choices came to reflect more closely the expected usage in the discipline, thus replicating the expected authorial voice for that particular audience. These cases demonstrate how "Try it on" can be used to help students write in an appropriate authorial voice while also avoiding plagiarism
Interface Dipole : Effects on Threshold Voltage and Mobility for both Amorphous and Poly-crystalline Organic Field Effect Transistors
We report a detailed comparison on the role of a self-assembled monolayer
(SAM) of dipolar molecules on the threshold voltage and charge carrier mobility
of organic field-effect transistor (OFET) made of both amorphous and
polycrystalline organic semiconductors. We show that the same relationship
between the threshold voltage and the dipole-induced charges in the SAM holds
when both types of devices are fabricated on strictly identical base
substrates. Charge carrier mobilities, almost constant for amorphous OFET, are
not affected by the dipole in the SAMs, while for polycrystalline OFET
(pentacene) the large variation of charge carrier mobilities is related to
change in the organic film structure (mostly grain size).Comment: Full paper and supporting informatio
Sample Police Officers Duty Manual
A police organization is that part of the government responsibile for enforcing laws and ordinances adopted by elected representatives of the people. The letter of the law determines what a police officer m ust do to discharge the obligation im posed by his oath, but it does not encom pass all of the circum stances which arise in the practical application of these written principles. Understanding of human behavior and application of comm on sense are fundamental to the successful attainment of police obj ectives. These alone, however, are not sufficient to insure the proper handling of every incident. There must be standards of quality and rules for procedure and conduct to serve as guides. These standards, rules and regulations are set forth in this Manual. This Manual prescribes the manner in which m embers of the Police Department will conduct them selves in discharging their sworn obligations. Violations of provisions of this Manual will constitute grounds for disciplinary action
3-dimensional Rules for Finite-Temperature Loops
We present simple diagrammatic rules to write down Euclidean n-point
functions at finite temperature directly in terms of 3-dimensional momentum
integrals, without ever performing a single Matsubara sum. The rules can be
understood as describing the interaction of the external particles with those
of the thermal bath.Comment: 12 pages, 4 figures, to appear in Physics Letters
Theoretical tools for atom laser beam propagation
We present a theoretical model for the propagation of non self-interacting
atom laser beams. We start from a general propagation integral equation, and we
use the same approximations as in photon optics to derive tools to calculate
the atom laser beam propagation. We discuss the approximations that allow to
reduce the general equation whether to a Fresnel-Kirchhoff integral calculated
by using the stationary phase method, or to the eikonal. Within the paraxial
approximation, we also introduce the ABCD matrices formalism and the beam
quality factor. As an example, we apply these tools to analyse the recent
experiment by Riou et al. [Phys. Rev. Lett. 96, 070404 (2006)]
Tuberculosis treatment in a refugee and migrant population: 20 years of experience on the Thai-Burmese border.
Although tuberculosis (TB) is a curable disease, it remains a major global health problem and an important cause of morbidity and mortality among vulnerable populations, including refugees and migrants
Mechanisms for Lasing with Cold Atoms as the Gain Medium
We realize a laser with a cloud of cold rubidium atoms as gain medium, placed
in a low-finesse cavity. Three different regimes of laser emission are observed
corresponding respectively to Mollow, Raman and Four Wave Mixing mechanisms. We
measure an output power of up to 300 W and present the main properties of
these different lasers in each regime
Electron transport through rectifying self-assembled monolayer diodes on silicon: Fermi level pinning at the molecule-metal interface
We report the synthesis and characterization of molecular rectifying diodes
on silicon using sequential grafting of self-assembled monolayers of alkyl
chains bearing a pi group at their outer end (Si/sigma-pi/metal junctions). We
investigate the structure-performance relationships of these molecular devices
and we examine to what extent the nature of the pi end-group (change in the
energy position of their molecular orbitals) drives the properties of these
molecular diodes. For all the pi-groups investigated here, we observe
rectification behavior. These results extend our preliminary work using phenyl
and thiophene groups (S. Lenfant et al., Nano Letters 3, 741 (2003)).The
experimental current-voltage curves are analyzed with a simple analytical
model, from which we extract the energy position of the molecular orbital of
the pi-group in resonance with the Fermi energy of the electrodes. We report
the experimental studies of the band lineup in these silicon/alkyl-pi
conjugated molecule/metal junctions. We conclude that Fermi level pinning at
the pi-group/metal interface is mainly responsible for the observed absence of
dependence of the rectification effect on the nature of the pi-groups, even
though they were chosen to have significant variations in their electronic
molecular orbitalsComment: To be published in J. Phys. Chem.
Optical parametric oscillation with distributed feedback in cold atoms
There is currently a strong interest in mirrorless lasing systems, in which
the electromagnetic feedback is provided either by disorder (multiple
scattering in the gain medium) or by order (multiple Bragg reflection). These
mechanisms correspond, respectively, to random lasers and photonic crystal
lasers. The crossover regime between order and disorder, or correlated
disorder, has also been investigated with some success. Here, we report
one-dimensional photonic-crystal lasing (that is, distributed feedback lasing)
with a cold atom cloud that simultaneously provides both gain and feedback. The
atoms are trapped in a one-dimensional lattice, producing a density modulation
that creates a strong Bragg reflection with a small angle of incidence. Pumping
the atoms with auxiliary beams induces four-wave mixing, which provides
parametric gain. The combination of both ingredients generates a mirrorless
parametric oscillation with a conical output emission, the apex angle of which
is tunable with the lattice periodicity
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