4,416 research outputs found
Diagnosing Emerging Fungal Threats: A One Health Perspective
Emerging fungal pathogens are a growing threat to global health, ecosystems, food security, and the world economy. Over the last century, environmental change and globalized transport, twinned with the increasing application of antifungal chemical drugs have led to increases in outbreaks of fungal diseases with sometimes catastrophic effects. In order to tackle contemporary epidemics and predemic threats, there is a pressing need for a unified approach in identification and monitoring of fungal pathogens. In this paper, we discuss current high throughput technologies, as well as new platforms capable of combining diverse data types to inform practical epidemiological strategies with a focus on emerging fungal pathogens of wildlife
Facile one-pot synthesis of amoxicillin-coated gold nanoparticles and their antimicrobial activity
Nanomaterials have been the object of intense study due to promising applications in a number of different disciplines. In particular, medicine and biology have seen the potential of these novel materials with their nanoscale properties for use in diverse areas such as imaging, sensing and drug vectorisation. Gold nanoparticles (GNPs) are considered a very useful platform to create a valid and efficient drug delivery/carrier system due to their facile and well-studied synthesis, easy surface functionalization and biocompatibility. In the present study, stable antibiotic conjugated GNPs were synthesised by a one-step reaction using a poorly water soluble antibiotic, amoxicillin. Amoxicillin, a member of the penicillin family, reduces the chloroauric acid to form nanoparticles and at the same time coats them to afford the functionalised nanomaterial. A range of techniques including UV-vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) were used to ascertain the gold/drug molar ratio and the optimum temperature for synthesis of uniform monodisperse particles in the ca. 30-40 nm size range. Amoxicillin-conjugated gold showed an enhancement of antibacterial activity against Escherichia coli compared to the antibiotic alone
Engineering Art Galleries
The Art Gallery Problem is one of the most well-known problems in
Computational Geometry, with a rich history in the study of algorithms,
complexity, and variants. Recently there has been a surge in experimental work
on the problem. In this survey, we describe this work, show the chronology of
developments, and compare current algorithms, including two unpublished
versions, in an exhaustive experiment. Furthermore, we show what core
algorithmic ingredients have led to recent successes
Involvement of mTOR in CXCL12 Mediated T Cell Signaling and Migration
CXCL12 is a pleiotropic chemokine involved in multiple different processes such as immune regulation, inflammatory responses, and cancer development. CXCL12 is also a potent chemokine involved in chemoattraction of T cells to the site of infection or inflammation. Mammalian target of rapamycin (mTOR) is a serine-threonine kinase that modulates different cellular processes, such as metabolism, nutrient sensing, protein translation, and cell growth. The role of mTOR in CXCL12-mediated resting T cell migration has yet to be elucidated.Rapamycin, an inhibitor of mTOR, significantly inhibits CXCL12 mediated migration of both primary human resting T cells and human T cell leukemia cell line CEM. p70(S6K1), an effector molecule of mTOR signaling pathway, was knocked down by shRNA in CEM cells using a lentiviral gene transfer system. Using p70(S6K1) knock down cells, we demonstrate the role of mTOR signaling in T cell migration both in vitro and in vivo.Our data demonstrate a new role for mTOR in CXCL12-induced T cell migration, and enrich the current knowledge regarding the clinical use of rapamycin
Accreting Neutron Stars in Low-Mass X-Ray Binary Systems
Using the Rossi X-ray Timing Explorer (RossiXTE), astronomers have discovered
that disk-accreting neutron stars with weak magnetic fields produce three
distinct types of high-frequency X-ray oscillations. These oscillations are
powered by release of the binding energy of matter falling into the strong
gravitational field of the star or by the sudden nuclear burning of matter that
has accumulated in the outermost layers of the star. The frequencies of the
oscillations reflect the orbital frequencies of gas deep in the gravitational
field of the star and/or the spin frequency of the star. These oscillations can
therefore be used to explore fundamental physics, such as strong-field gravity
and the properties of matter under extreme conditions, and important
astrophysical questions, such as the formation and evolution of millisecond
pulsars. Observations using RossiXTE have shown that some two dozen neutron
stars in low-mass X-ray binary systems have the spin rates and magnetic fields
required to become millisecond radio-emitting pulsars when accretion ceases,
but that few have spin rates above about 600 Hz. The properties of these stars
show that the paucity of spin rates greater than 600 Hz is due in part to the
magnetic braking component of the accretion torque and to the limited amount of
angular momentum that can be accreted in such systems. Further study will show
whether braking by gravitational radiation is also a factor. Analysis of the
kilohertz oscillations has provided the first evidence for the existence of the
innermost stable circular orbit around dense relativistic stars that is
predicted by strong-field general relativity. It has also greatly narrowed the
possible descriptions of ultradense matter.Comment: 22 pages, 7 figures, updated list of sources and references, to
appear in "Short-period Binary Stars: Observation, Analyses, and Results",
eds. E.F. Milone, D.A. Leahy, and D. Hobill (Dordrecht: Springer,
http://www.springerlink.com
Of cattle, sand flies and men : a systematic review of risk factor analyses for South Asian visceral leishmaniasis and implications for elimination
Background: Studies performed over the past decade have identified fairly consistent epidemiological patterns of risk
factors for visceral leishmaniasis (VL) in the Indian subcontinent.
Methods and Principal Findings: To inform the current regional VL elimination effort and identify key gaps in knowledge,
we performed a systematic review of the literature, with a special emphasis on data regarding the role of cattle because
primary risk factor studies have yielded apparently contradictory results. Because humans form the sole infection reservoir,
clustering of kala-azar cases is a prominent epidemiological feature, both at the household level and on a larger scale.
Subclinical infection also tends to show clustering around kala-azar cases. Within villages, areas become saturated over a
period of several years; kala-azar incidence then decreases while neighboring areas see increases. More recently, post kalaazar
dermal leishmaniasis (PKDL) cases have followed kala-azar peaks. Mud walls, palpable dampness in houses, and peridomestic
vegetation may increase infection risk through enhanced density and prolonged survival of the sand fly vector.
Bed net use, sleeping on a cot and indoor residual spraying are generally associated with decreased risk. Poor micronutrient
status increases the risk of progression to kala-azar. The presence of cattle is associated with increased risk in some studies
and decreased risk in others, reflecting the complexity of the effect of bovines on sand fly abundance, aggregation, feeding
behavior and leishmanial infection rates. Poverty is an overarching theme, interacting with individual risk factors on multiple
levels.
Conclusions: Carefully designed demonstration projects, taking into account the complex web of interconnected risk
factors, are needed to provide direct proof of principle for elimination and to identify the most effective maintenance
activities to prevent a rapid resurgence when interventions are scaled back. More effective, short-course treatment
regimens for PKDL are urgently needed to enable the elimination initiative to succeed
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Sponsor ownership in Asian REITs
This study examines the relationship between sponsor ownership and firm performance proxied by firm value, operating cash flow, and dividend policy with Asian real estate investment trusts (REITs) in Japan, Hong Kong, Malaysia, and Singapore for the period from 2002 to 2012, focusing on both the incentive alignment effect and the entrenchment effect. Our study sheds new light on effective corporate governance for Asian REITs that are prone to agency problems. Such agency problems arise from the inequitable distribution of power to sponsors that results from the external management structure. The findings suggest that larger sponsor ownership aligns the interests of sponsors and minority shareholders and enhances the performance of Asian REITs, while such an effect diminishes as sponsors become more entrenched. We find that the incentive alignment effect and entrenchment effect are primarily driven by developer-sponsored REITs. Also evident is that the presence of institutional investors mitigates agency problems and increases firm performance
Verticalization of bacterial biofilms
Biofilms are communities of bacteria adhered to surfaces. Recently, biofilms
of rod-shaped bacteria were observed at single-cell resolution and shown to
develop from a disordered, two-dimensional layer of founder cells into a
three-dimensional structure with a vertically-aligned core. Here, we elucidate
the physical mechanism underpinning this transition using a combination of
agent-based and continuum modeling. We find that verticalization proceeds
through a series of localized mechanical instabilities on the cellular scale.
For short cells, these instabilities are primarily triggered by cell division,
whereas long cells are more likely to be peeled off the surface by nearby
vertical cells, creating an "inverse domino effect". The interplay between cell
growth and cell verticalization gives rise to an exotic mechanical state in
which the effective surface pressure becomes constant throughout the growing
core of the biofilm surface layer. This dynamical isobaricity determines the
expansion speed of a biofilm cluster and thereby governs how cells access the
third dimension. In particular, theory predicts that a longer average cell
length yields more rapidly expanding, flatter biofilms. We experimentally show
that such changes in biofilm development occur by exploiting chemicals that
modulate cell length.Comment: Main text 10 pages, 4 figures; Supplementary Information 35 pages, 15
figure
Entangled Quantum States of Magnetic Dipoles
Free magnetic moments usually manifest themselves in Curie Laws, where weak
external magnetic fields produce magnetizations diverging as the reciprocal 1/T
of the temperature. for a variety of materials that do not disply static
magnetism, including doped semiconductors and certain rare earth
intermetallics, the 1/T law is changed to a power law T^-a with a<1. We report
here that a considerably simpler material, namely an insulating magneticsalt
can also display such a power law, and show via comparison to specific heat
data and numerical simulations that quantum mechanics is crucial for its
formation. Two quantum mechanical phenomena are needed, namely level splitting
- which affects the spectrum of excited states - and entanglement - where the
wavefunction of a system with several degrees of freedom cannot be written as a
product of wavefunctions for each degree of freedom. Entanglement effects
become visible for remarkably small tunnelling terms, and are turned on well
before tunnelling has visible effects on the spectrum. Our work is significant
because it illustrates that entanglement is at the very heart of a very simple
experimental observation for an insulating quantum spin system.Comment: 17 pages, 4 figure
Dynamical R-parity Breaking at the LHC
In a class of extensions of the minimal supersymmetric standard model with
(B-L)/left-right symmetry that explains the neutrino masses, breaking R-parity
symmetry is an essential and dynamical requirement for successful gauge
symmetry breaking. Two consequences of these models are: (i) a new kind of
R-parity breaking interaction that protects proton stability but adds new
contributions to neutrinoless double beta decay and (ii) an upper bound on the
extra gauge and parity symmetry breaking scale which is within the large hadron
collider (LHC) energy range. We point out that an important prediction of such
theories is a potentially large mixing between the right-handed charged lepton
() and the superpartner of the right-handed gauge boson (), which leads to a brand new class of R-parity violating interactions of
type and \widetilde{d^c}^\dagger\u^c
e^c. We analyze the relevant constraints on the sparticle mass spectrum and
the LHC signatures for the case with smuon/stau NLSP and gravitino LSP. We note
the "smoking gun" signals for such models to be lepton flavor/number violating
processes: (or ) and
(or ) without
significant missing energy. The predicted multi-lepton final states and the
flavor structure make the model be distinguishable even in the early running of
the LHC.Comment: 30 pages, 13 figures, 6 tables, reference adde
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