2,460 research outputs found
Breaking boundaries for biodiversity : expanding the policy agenda to halt biodiversity loss
Our assessment from the perspective of the Netherlands, a country in the temperate zone, showed a slightly positive picture, in line with the overall results for this zone. The loss of biodiversity in the Netherlands has been slowed down, but the European target – halting the loss of biodiversity – could not be met. The picture in the Netherlands is less positive if the average low quality of the remaining Dutch biodiversity is taken into account. If the impacts on biodiversity abroad of imports into the Netherlands are also included, we conclude that the Netherlands is not succeeding in slowing down the loss of biodiversity
On the averaging principle for one-frequency systems. An application to satellite motions
This paper is related to our previous works [1][2] on the error estimate of
the averaging technique, for systems with one fast angular variable. In the
cited references, a general method (of mixed analytical and numerical type) has
been introduced to obtain precise, fully quantitative estimates on the
averaging error. Here, this procedure is applied to the motion of a satellite
in a polar orbit around an oblate planet, retaining only the J_2 term in the
multipole expansion of the gravitational potential. To exemplify the method,
the averaging errors are estimated for the data corresponding to two Earth
satellites; for a very large number of orbits, computation of our estimators is
much less expensive than the direct numerical solution of the equations of
motion.Comment: LaTeX, 35 pages, 12 figures. The final version published in Nonlinear
Dynamic
Haemolytic uraemic syndrome following Shigella dysenteriae type 1 outbreak in Zimbabwe: a clinical experience
A CAJM article on dysentry outbreak in Zimbabwe.Shigella dysenteriae type 1 related dysentery outbreak in Zimbabwe at the end of 1992 has been associated with an increase in the frequency of haemolytic uraemic syndrome (HUS). In order to document this new clinical experience a retrospective study was undertaken to document clinical and laboratory features, treatment and outcome of children with HUS
On the averaging principle for one-frequency systems. Seminorm estimates for the error
We extend some previous results of our work [1] on the error of the averaging
method, in the one-frequency case. The new error estimates apply to any
separating family of seminorms on the space of the actions; they generalize our
previous estimates in terms of the Euclidean norm. For example, one can use the
new approach to get separate error estimates for each action coordinate. An
application to rigid body under damping is presented. In a companion paper [2],
the same method will be applied to the motion of a satellite around an oblate
planet.Comment: LaTeX, 23 pages, 4 figures. The final version published in Nonlinear
Dynamic
Non-responsive coeliac disease : a comprehensive review from the NHS England national centre for refractory coeliac disease
Coeliac disease is a common small intestinal enteropathy which manifests following ingestion of gluten in genetically susceptible individuals. Since gluten was identified as the driving factor in coeliac disease, the gluten-free diet (GFD) has remained the mainstay of treatment. While most individuals will display improvement in symptoms and signs of coeliac disease following institution of the GFD, up to 30% will continue to experience symptoms and/or have persisting intestinal inflammation. These individuals can be classified as having non-responsive coeliac disease (NRCD), which may be associated with dietary indiscretion, slow healing, refractory coeliac disease, and/or an alternative condition. The purpose of this review is to provide an overview of the causes of NRCD in adults, highlight a systematic approach to investigate these patients, and appraise the latest management aspects of this subset of coeliac disease
The recognition of acted interpersonal stance in police interrogations
This research aims at finding how suspects in police interrogations express their interpersonal stance -in terms of T.Leary’s interpersonal circumplex- through body postures and facial expressions and how this can be simulated by virtual humans. Therefore, four types of stances were acted by eight actors. To see if the resulted postures are valid, short recordings were shown online in a survey to subjects who were asked to describe them by a selection of a number of adjectives. Results of this annotation task show that some stance types are better recognized than others. Validity (recognizing the intended stance) and inter-rater agreement do not always go hand in hand. The body postures and facial expressions of the best recognized fragments are annotated so they can be implemented in the artificial agent. The results of this study are used in a serious game for police interrogation training where the role of the suspect is played by an artificial embodied conversational agent
Herbivorous turtle ants obtain essential nutrients from a conserved nitrogen-recycling gut microbiome.
Nitrogen acquisition is a major challenge for herbivorous animals, and the repeated origins of herbivory across the ants have raised expectations that nutritional symbionts have shaped their diversification. Direct evidence for N provisioning by internally housed symbionts is rare in animals; among the ants, it has been documented for just one lineage. In this study we dissect functional contributions by bacteria from a conserved, multi-partite gut symbiosis in herbivorous Cephalotes ants through in vivo experiments, metagenomics, and in vitro assays. Gut bacteria recycle urea, and likely uric acid, using recycled N to synthesize essential amino acids that are acquired by hosts in substantial quantities. Specialized core symbionts of 17 studied Cephalotes species encode the pathways directing these activities, and several recycle N in vitro. These findings point to a highly efficient N economy, and a nutritional mutualism preserved for millions of years through the derived behaviors and gut anatomy of Cephalotes ants
Physical Optimization of Quantum Error Correction Circuits
Quantum error correcting codes have been developed to protect a quantum
computer from decoherence due to a noisy environment. In this paper, we present
two methods for optimizing the physical implementation of such error correction
schemes. First, we discuss an optimal quantum circuit implementation of the
smallest error-correcting code (the three bit code). Quantum circuits are
physically implemented by serial pulses, i.e. by switching on and off external
parameters in the Hamiltonian one after another. In contrast to this, we
introduce a new parallel switching method that allows faster gate operation by
switching all external parameters simultaneously. These two methods are applied
to electron spins in coupled quantum dots subject to a Heisenberg coupling
H=J(t) S_1*S_2 which can generate the universal quantum gate
`square-root-of-swap'. Using parallel pulses, the encoding for three-bit
quantum error correction in a Heisenberg system can be accelerated by a factor
of about two. We point out that parallel switching has potential applications
for arbitrary quantum computer architectures.Comment: 13 pages, 6 figure
Stability of axial orbits in galactic potentials
We investigate the dynamics in a galactic potential with two reflection
symmetries. The phase-space structure of the real system is approximated with a
resonant detuned normal form constructed with the method based on the Lie
transform. Attention is focused on the stability properties of the axial
periodic orbits that play an important role in galactic models. Using energy
and ellipticity as parameters, we find analytical expressions of bifurcations
and compare them with numerical results available in the literature.Comment: 20 pages, accepted for publication on Celestial Mechanics and
Dynamical Astronom
Homodyne Bell's inequalities for entangled mesoscopic superpositions
We present a scheme for demonstrating violation of Bell's inequalities using
a spin-1/2 system entangled with a pair of classically distinguishable wave
packets in a harmonic potential. In the optical domain, such wave packets can
be represented by coherent states of a single light mode. The proposed scheme
involves standard spin-1/2 projections and measurements of the position and the
momentum of the harmonic oscillator system, which for a light mode can be
realized by means of homodyne detection. We discuss effects of imperfections,
including non-unit efficiency of the homodyne detector, and point out a close
link between the visibility of interference and violation of Bell's
inequalities in the described scheme.Comment: 6 pages, 3 figures. Extended version, journal reference adde
- …