1,569 research outputs found
Reduction of antibiotic use and antibiotic resistance in commercial poultry
Use of antibiotics for companion animals and livestock in the Netherlands has reduced by more than 60% over the last 10 years (SDa 2019; MARAN-2019). This reduction is the result of a change in policy towards the use of antibiotics in veterinary practice and is characterized by a series of coherent political decisions which changed the playing field for farmers and veterinarians considerably. In the years before 2009 the Netherlands was a high consumer of antibiotics in veterinary practice (Grave et al., 2010). The ban of antimicrobial growth promoters (AGPs) did not result in a reduction in total use since in the Netherlands the AGPs were fully replaced by antibiotics licensed for therapy. The total sales of all antibiotics remained stable at around 600 tons from 2000 to 2009.This use pattern resulted in high levels of antimicrobial resistance in bacteria from livestock and food thereof and high prevalence of Livestock Associated MRSA and ESBL-producing E. coli and Salmonella (MARAN, 2019; RIVM, 2009). Specifically, ESBL-producing isolates in the food chain were considered a risk for public health and their high prevalences, predominantly but not solely in poultry and poultry meat products were the direct reason to initiate the change in policy towards antibiotic use in animals.In this manuscript the trends in antibiotic use in poultry will be explored in the context of total use in livestock and its effect on the occurrence and trends in ESBL-producers and antimicrobial resistance in other bacterial species from poultry
Modified gravity without dark matter
On an empirical level, the most successful alternative to dark matter in
bound gravitational systems is the modified Newtonian dynamics, or MOND,
proposed by Milgrom. Here I discuss the attempts to formulate MOND as a
modification of General Relativity. I begin with a summary of the
phenomenological successes of MOND and then discuss the various covariant
theories that have been proposed as a basis for the idea. I show why these
proposals have led inevitably to a multi-field theory. I describe in some
detail TeVeS, the tensor-vector-scalar theory proposed by Bekenstein, and
discuss its successes and shortcomings. This lecture is primarily pedagogical
and directed to those with some, but not a deep, background in General
RelativityComment: 28 pages, 10 figures, lecture given at Third Aegean Summer School,
The Invisible Universe: Dark Matter and Dark Energy, minor errors corrected,
references update
Are parent-reported outcomes for self-directed or telephone-assisted behavioral family intervention enhanced if parents are observed?
The study examined the effects of conducting observations as part of a broader assessment of families participating in behavior family intervention (BFI). It was designed to investigate whether the observations improve intervention outcomes. Families were randomly assigned to different levels of BFI or a waitlist control condition and subsequently randomly assigned to either observation or no-observation conditions. This study demonstrated significant intervention and observation effects. Mothers in more intensive BFI reported more improvement in their child’s behavior and their own parenting. Observed mothers reported lower intensity of child behavior problems and more effective parenting styles. There was also a trend for less anger among mothers who were observed and evidence of an observation-intervention interaction for parental anger, with observed mothers in more intensive intervention reporting less anger compared to those not observed. Implications for clinical and research intervention contexts are discussed
High export via small particles before the onset of the North Atlantic spring bloom
Sinking organic matter in the North Atlantic Ocean transfers 1-3 Gt carbon year?1 from the surface ocean to the interior. The majority of this exported material is thought to be in form of large, rapidly sinking particles that aggregate during or after the spring phytoplankton bloom. However, recent work has suggested that intermittent water column stratification resulting in the termination of deep convection can isolate phytoplankton from the euphotic zone, leading to export of small particles. We present depth profiles of large (>0.1mm equivalent spherical diameter, ESD) and small (300m depth, leading to deep mixing of particles as deep as 600m. Subsequent re-stratification could trap these particles at depth and lead to high particle fluxes at depth without the need for aggregation (‘mixed layer pump'). Overall we suggest that pre-bloom fluxes to the mesopelagic are significant, and the role of small sinking particles requires careful consideration
Measuring Pancharatnam's relative phase for SO(3) evolutions using spin polarimetry
In polarimetry, a superposition of internal quantal states is exposed to a
single Hamiltonian and information about the evolution of the quantal states is
inferred from projection measurements on the final superposition. In this
framework, we here extend the polarimetric test of Pancharatnam's relative
phase for spin proposed by Wagh and Rakhecha [Phys. Lett. A {\bf 197},
112 (1995)] to spin undergoing noncyclic SO(3) evolution. We
demonstrate that the output intensity for higher spin values is a polynomial
function of the corresponding spin intensity. We further propose a
general method to extract the noncyclic SO(3) phase and visibility by rigid
translation of two spin flippers. Polarimetry on higher spin states
may in practice be done with spin polarized atomic beams.Comment: New title, minor corrections, journal reference adde
High export via small particles before the onset of the North Atlantic spring bloom
Sinking organic matter in the North Atlantic Ocean transfers 1-3 Gt carbon year?1 from the surface ocean to the interior. The majority of this exported material is thought to be in form of large, rapidly sinking particles that aggregate during or after the spring phytoplankton bloom. However, recent work has suggested that intermittent water column stratification resulting in the termination of deep convection can isolate phytoplankton from the euphotic zone, leading to export of small particles. We present depth profiles of large (>0.1mm equivalent spherical diameter, ESD) and small (<0.1mm ESD) sinking particle concentrations and fluxes prior to the spring bloom at two contrasting sites in the North Atlantic (61°30N, 11°00W and 62°50N, 02°30W) derived from the Marine Snow Catcher and the Video Plankton Recorder. The downward flux of organic carbon via small particles ranged from 23-186 mg C m?2 d?1, often constituting the bulk of the total particulate organic carbon flux. We propose that these rates were driven by two different mechanisms: In the Norwegian Basin, small sinking particles likely reached the upper mesopelagic by disaggregation of larger, faster sinking particles. In the Iceland Basin, a storm deepened the mixed layer to >300m depth, leading to deep mixing of particles as deep as 600m. Subsequent re-stratification could trap these particles at depth and lead to high particle fluxes at depth without the need for aggregation (‘mixed layer pump'). Overall we suggest that pre-bloom fluxes to the mesopelagic are significant, and the role of small sinking particles requires careful consideration. <br/
Spin squeezing and pairwise entanglement for symmetric multiqubit states
We show that spin squeezing implies pairwise entanglement for arbitrary
symmetric multiqubit states. If the squeezing parameter is less than or equal
to 1, we demonstrate a quantitative relation between the squeezing parameter
and the concurrence for the even and odd states. We prove that the even states
generated from the initial state with all qubits being spin down, via the
one-axis twisting Hamiltonian, are spin squeezed if and only if they are
pairwise entangled. For the states generated via the one-axis twisting
Hamiltonian with an external transverse field for any number of qubits greater
than 1 or via the two-axis counter-twisting Hamiltonian for any even number of
qubits, the numerical results suggest that such states are spin squeezed if and
only if they are pairwise entangled.Comment: 6 pages. Version 3: Small corrections were mad
High-Energy Cosmology: gamma rays and neutrinos from beyond the galaxy
Our knowledge of the high-energy universe is undergoing a period of rapid
change as new astronomical detectors of high-energy radiation start to operate
at their design sensitivities. Now is a boomtime for high-energy astrophysics,
with new discoveries from Swift and HESS, results from MAGIC and VERITAS
starting to be reported, the upcoming launches of the gamma-ray space
telescopes GLAST and AGILE, and anticipated data releases from IceCube and
Auger. A formalism for calculating statistical properties of cosmological
gamma-ray sources is presented. Application is made to model calculations of
the statistical distributions of gamma-ray and neutrino emission from (i)
beamed sources, specifically, long-duration GRBs, blazars, and extagalactic
microquasars, and (ii) unbeamed sources, including normal galaxies, starburst
galaxies and clusters. Expressions for the integrated intensities of faint
beamed and unbeamed high-energy radiation sources are also derived. A toy model
for the background intensity of radiation from dark-matter annihilation taking
place in the early universe is constructed. Estimates for the gamma-ray fluxes
of local group galaxies, starburst, and infrared luminous galaxies are briefly
reviewed. Because the brightest extragalactic gamma-ray sources are flaring
sources, and these are the best targets for sources of PeV -- EeV neutrinos and
ultra-high energy cosmic rays, rapidly slewing all-sky telescopes like MAGIC
and an all-sky gamma-ray observatory beyond Milagro will be crucial for optimal
science return in the multi-messenger age.Comment: 10 pages, 3 figs, accepted for publication in the Barcelona
Conference on Multimessenger Astronomy; corrected eq. 27, revised Fig. 3,
added 2 ref
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Unified concepts for understanding and modelling turnover of dissolved organic matter from freshwaters to the ocean: the UniDOM model
The transport of dissolved organic matter (DOM) across the land-ocean-aquatic continuum (LOAC), from freshwater to the ocean, is an important yet poorly understood component of the global carbon budget. Exploring and quantifying this flux is a significant challenge given the complexities of DOM cycling across these contrasting environments. We developed a new model, UniDOM, that unifies concepts, state variables and parameterisations of DOM turnover across the LOAC. Terrigenous DOM is divided into two pools, T1 (strongly-UV-absorbing) and T2 (non- or weakly-UV-absorbing), that exhibit contrasting responses to microbial consumption, photooxidation and flocculation. Data are presented to show that these pools are amenable to routine measurement based on specific UV absorbance (SUVA). In addition, an autochtonous DOM pool is defined to account for aquatic DOM production. A novel aspect of UniDOM is that rates of photooxidation and microbial turnover are parameterised as an inverse function of DOM age. Model results, which indicate that ~5% of the DOM originating in streams may penetrate into the open ocean, are sensitive to this parameterisation, as well as rates assigned to turnover of freshly produced DOM. The predicted contribution of flocculation to DOM turnover is remarkably low, although a mechanistic representation of this process in UniDOM was considered unachievable because of the complexities involved. Our work highlights the need for ongoing research into the mechanistic understanding and rates of photooxidation, microbial consumption and flocculation of DOM across the different environments of the LOAC, along with the development of models based on unified concepts and parameterisations
Binary decay of Ni56 formed in the 32S+24Mg reaction
Fully energy-damped yields from the Mg32 reaction have been measured at center-of-mass energies of Ec.m.=51.6 and 60.5 MeV with the use of an experimental arrangement where both of the resulting heavy fragments could be detected in coincidence. Energy, velocity, and angular distributions of the reaction fragments have been determined. The cross sections prior to secondary light-particle emission have been deduced for the breakup of the compound system into different mass channels. These data are discussed in terms of two possible reaction mechanisms: fusion followed by fission and deep-inelastic orbiting
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