1,638 research outputs found
The potential impact of BCG vaccine supply shortages on global paediatric tuberculosis mortality.
BACKGROUND: The Bacillus Calmette-Guérin (BCG) vaccine is provided to over 100 million neonates annually to protect against childhood tuberculosis (TB). Recent BCG manufacturing interruptions highlight global supply risks. We estimated the potential impact of BCG shortfalls on global paediatric (<15 years) TB mortality. METHODS: A static mathematical model was employed to estimate the number of paediatric TB deaths avoided by usual levels of BCG coverage, and potential additional TB deaths in the first 15 years of life due to 1-year BCG supply shortfalls of 6.3 % (as occurred in 2015) to 27.6 % (as anticipated without mitigating action in 2015) assuming no catch-up campaigns. RESULTS: BCG coverage without shortfalls, estimated at 90 % globally, was estimated to avoid 117,132 (95 % uncertainty range (UR): 5049-306,911) TB deaths globally per birth cohort in the first 15 years of life. An estimated 11,713 (UR: 505-30,691) additional TB deaths would occur in the first 15 years of life per 10 % (26 million dose) annual supply shortfall. A 16.5 million dose (6.3 %) shortfall as reported at the close of 2015, reflecting 84 % global coverage, was estimated as associated with 7433 (95 % UR: 320-19,477) excess TB deaths in the affected cohort in the first 15 years. A possible 24,914 (UR: 1074-65,278) additional deaths were avoided due to prompt shortfall reduction measures in 2015. CONCLUSIONS: BCG shortages could greatly increase paediatric TB mortality. Although rapid action in 2015 minimised BCG shortfalls, avoiding a large number of potential additional deaths, the possible public health impact of even relatively small shortfalls highlights the critical importance of ensuring secure future manufacturing capacity and global BCG supply continuity
A simulated study of implicit feedback models
In this paper we report on a study of implicit feedback models for unobtrusively tracking the information needs of searchers. Such models use relevance information gathered from searcher interaction and can be a potential substitute for explicit relevance feedback. We introduce a variety of implicit feedback models designed to enhance an Information Retrieval (IR) system's representation of searchers' information needs. To benchmark their performance we use a simulation-centric evaluation methodology that measures how well each model learns relevance and improves search effectiveness. The results show that a heuristic-based binary voting model and one based on Jeffrey's rule of conditioning [5] outperform the other models under investigation
Thinking Digitally, Together: Models for Digital Scholarship at Gettysburg College
Systems Librarian R.C. Miessler, College Archivist Amy Lucadamo, and senior Lauren White, discuss how Musselman Library has been involved in digital scholarship conversations and activities at Gettysburg, and invite discussion on how a campus-wide model for digital scholarship could emerge
#dssf16+1: Library-led Digital Scholarship for Undergraduates at a Small Institution
Librarian R.C. Miessler and Digital Scholarship Fellows Keira Koch, Julia Wall, and Lauren White were invited to speak to at the Pennsylvania Library Association, College and Research Division, Spring Conference about their experiences with the first cohort of the Digital Scholarship Summer Fellowship
#dssf16: Library-led Digital Scholarship for Undergraduates at a Small Institution
In the summer of 2016, Gettysburg College’s Musselman Library piloted the Digital Scholarship Summer Fellowship (DSSF), a library-led, student-centered introduction to digital scholarship. The Fellowship, a 10-week, paid, summer program for rising sophomores and juniors, is programmatic, based on a curriculum designed to introduce the student fellows to digital tools, project management, documentation, and the philosophy behind digital scholarship. The Fellowship aimed to create a digital scholarship community of practice at Gettysburg College, collaborating with educational technologists and faculty engaged in digital scholarship to support the needs of the first cohort; in addition, the Fellowship supported the digital scholarship activities of students participating in other summer research programs. R.C. Miessler, coordinator of the Digital Scholarship Summer Fellowship, will discuss the creation, development, implementation, and future of the program. The student fellows, Keira Koch, Julia Wall, and Lauren White, will reflect on their experience and present the digital projects they created
Outskirts of Nearby Disk Galaxies: Star Formation and Stellar Populations
The properties and star formation processes in the far-outer disks of nearby
spiral and dwarf irregular galaxies are reviewed. The origin and structure of
the generally exponential profiles in stellar disks is considered to result
from cosmological infall combined with a non-linear star formation law and a
history of stellar migration and scattering from spirals, bars, and random
collisions with interstellar clouds. In both spirals and dwarfs, the far-outer
disks tend to be older, redder and thicker than the inner disks, with the
overall radial profiles suggesting inside-out star formation plus stellar
scattering in spirals, and outside-in star formation with a possible
contribution from scattering in dwarfs. Dwarf irregulars and the far-outer
parts of spirals both tend to be gas dominated, and the gas radial profile is
often non-exponential although still decreasing with radius. The ratio of
H-alpha to far-UV flux tends to decrease with lower surface brightness in these
regions, suggesting either a change in the initial stellar mass function or the
sampling of that function, or a possible loss of H-alpha photons.Comment: 20 pages, 8 figures, Invited review, Book chapter in "Outskirts of
Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and
Space Science Library, Springer, in pres
Magnetoresistance of Granular Ferromagnets - Observation of a Magnetic Proximity Effect?
We have observed a superparamagnetic to ferromagnetic transition in films of
isolated Ni grains covered by non-magnetic overlayers. The magnetoresistance
(MR) of the films was measured as a function of the overlayer thickness.
Initially, the granular Ni films exhibited negative MR curves peaked at H=0. As
different materials were deposited onto the grains hysteresis developed in the
MR. This behavior is ascribed to an increase of the typical domain size due to
magnetic coupling between grains. The strength of the inter-grain coupling is
found to correlate with the magnetic susceptibility of the overlayer material.
We discuss possible mechanisms for this coupling and suggest that the data may
reflect the existence of a magnetic proximity effect (analogous to the
well-known effect in superconductivity) in which a ferromagnetic moment is
induced in the metallic non-magnetic medium.Comment: 4 pages, 5 figure
Superconductors with Magnetic Impurities: Instantons and Sub-gap States
When subject to a weak magnetic impurity potential, the order parameter and
quasi-particle energy gap of a bulk singlet superconductor are suppressed.
According to the conventional mean-field theory of Abrikosov and Gor'kov, the
integrity of the energy gap is maintained up to a critical concentration of
magnetic impurities. In this paper, a field theoretic approach is developed to
critically analyze the validity of the mean field theory. Using the
supersymmetry technique we find a spatially homogeneous saddle-point that
reproduces the Abrikosov-Gor'kov theory, and identify instanton contributions
to the density of states that render the quasi-particle energy gap soft at any
non-zero magnetic impurity concentration. The sub-gap states are associated
with supersymmetry broken field configurations of the action. An analysis of
fluctuations around these configurations shows how the underlying supersymmetry
of the action is restored by zero modes. An estimate of the density of states
is given for all dimensionalities. To illustrate the universality of the
present scheme we apply the same method to study `gap fluctuations' in a normal
quantum dot coupled to a superconducting terminal. Using the same instanton
approach, we recover the universal result recently proposed by Vavilov et al.
Finally, we emphasize the universality of the present scheme for the
description of gap fluctuations in d-dimensional superconducting/normal
structures.Comment: 18 pages, 9 eps figure
Distributed Management of Massive Data: an Efficient Fine-Grain Data Access Scheme
This paper addresses the problem of efficiently storing and accessing massive
data blocks in a large-scale distributed environment, while providing efficient
fine-grain access to data subsets. This issue is crucial in the context of
applications in the field of databases, data mining and multimedia. We propose
a data sharing service based on distributed, RAM-based storage of data, while
leveraging a DHT-based, natively parallel metadata management scheme. As
opposed to the most commonly used grid storage infrastructures that provide
mechanisms for explicit data localization and transfer, we provide a
transparent access model, where data are accessed through global identifiers.
Our proposal has been validated through a prototype implementation whose
preliminary evaluation provides promising results
The phase relation between sunspot numbers and soft X-ray flares
To better understand long-term flare activity, we present a statistical study
on soft X-ray flares from May 1976 to May 2008. It is found that the smoothed
monthly peak fluxes of C-class, M-class, and X-class flares have a very
noticeable time lag of 13, 8, and 8 months in cycle 21 respectively with
respect to the smoothed monthly sunspot numbers. There is no time lag between
the sunspot numbers and M-class flares in cycle 22. However, there is a
one-month time lag for C-class flares and a one-month time lead for X-class
flares with regard to sunspot numbers in cycle 22. For cycle 23, the smoothed
monthly peak fluxes of C-class, M-class, and X-class flares have a very
noticeable time lag of one month, 5 months, and 21 months respectively with
respect to sunspot numbers. If we take the three types of flares together, the
smoothed monthly peak fluxes of soft X-ray flares have a time lag of 9 months
in cycle 21, no time lag in cycle 22 and a characteristic time lag of 5 months
in cycle 23 with respect to the smoothed monthly sunspot numbers. Furthermore,
the correlation coefficients of the smoothed monthly peak fluxes of M-class and
X-class flares and the smoothed monthly sunspot numbers are higher in cycle 22
than those in cycles 21 and 23. The correlation coefficients between the three
kinds of soft X-ray flares in cycle 22 are higher than those in cycles 21 and
23. These findings may be instructive in predicting C-class, M-class, and
X-class flares regarding sunspot numbers in the next cycle and the physical
processes of energy storage and dissipation in the corona.Comment: 8 pages, 3 figures, Accepted for publication in Astrophysics & Space
Scienc
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