544 research outputs found
Sequence of the OXA2 β-lactamase: comparison with other penicillin-reactive enzymes
AbstractThe nucleotide sequence of the unusual plasmid-mediated OXA2 β-lactamase is presented, and compared with other β-lactamases. The OXA2 enzyme has similar features at the presumed active site, but no other significant regions ofhomology with other penicillin-reactive enzymes. The active site homology may therefore represent convergent evolution of otherwise dissimilar genes
Population Monte Carlo algorithms
We give a cross-disciplinary survey on ``population'' Monte Carlo algorithms.
In these algorithms, a set of ``walkers'' or ``particles'' is used as a
representation of a high-dimensional vector. The computation is carried out by
a random walk and split/deletion of these objects. The algorithms are developed
in various fields in physics and statistical sciences and called by lots of
different terms -- ``quantum Monte Carlo'', ``transfer-matrix Monte Carlo'',
``Monte Carlo filter (particle filter)'',``sequential Monte Carlo'' and
``PERM'' etc. Here we discuss them in a coherent framework. We also touch on
related algorithms -- genetic algorithms and annealed importance sampling.Comment: Title is changed (Population-based Monte Carlo -> Population Monte
Carlo). A number of small but important corrections and additions. References
are also added. Original Version is read at 2000 Workshop on
Information-Based Induction Sciences (July 17-18, 2000, Syuzenji, Shizuoka,
Japan). No figure
A classification of smooth embeddings of 3-manifolds in 6-space
We work in the smooth category. If there are knotted embeddings S^n\to R^m,
which often happens for 2m<3n+4, then no concrete complete description of
embeddings of n-manifolds into R^m up to isotopy was known, except for disjoint
unions of spheres. Let N be a closed connected orientable 3-manifold. Our main
result is the following description of the set Emb^6(N) of embeddings N\to R^6
up to isotopy.
The Whitney invariant W : Emb^6(N) \to H_1(N;Z) is surjective. For each u \in
H_1(N;Z) the Kreck invariant \eta_u : W^{-1}u \to Z_{d(u)} is bijective, where
d(u) is the divisibility of the projection of u to the free part of H_1(N;Z).
The group Emb^6(S^3) is isomorphic to Z (Haefliger). This group acts on
Emb^6(N) by embedded connected sum. It was proved that the orbit space of this
action maps under W bijectively to H_1(N;Z) (by Vrabec and Haefliger's
smoothing theory). The new part of our classification result is determination
of the orbits of the action. E. g. for N=RP^3 the action is free, while for
N=S^1\times S^2 we construct explicitly an embedding f : N \to R^6 such that
for each knot l:S^3\to R^6 the embedding f#l is isotopic to f.
Our proof uses new approaches involving the Kreck modified surgery theory or
the Boechat-Haefliger formula for smoothing obstruction.Comment: 32 pages, a link to http://www.springerlink.com added, to appear in
Math. Zei
Different value of coronary calcium score to predict obstructive coronary artery disease in patients with and without moderate chronic kidney disease.
published_or_final_versio
On complex surfaces diffeomorphic to rational surfaces
In this paper we prove that no complex surface of general type is
diffeomorphic to a rational surface, thereby completing the smooth
classification of rational surfaces and the proof of the Van de Ven conjecture
on the smooth invariance of Kodaira dimension.Comment: 34 pages, AMS-Te
Towards a global platform for linking soil biodiversity data
Soil biodiversity is immense, with an estimated 10–100 million organisms belonging to over 5000 taxa in a handful of soil. In spite of the importance of soil biodiversity for ecosystem functions and services, information on soil species, from taxonomy to biogeographical patterns, is incomplete and there is no infrastructure to connect pre-existing or future data. Here, we propose a global platform to allow for greater access to soil biodiversity information by linking databases and repositories through a single open portal. The proposed platform would for the first time, link data on soil organisms from different global sites and biomes, and will be inclusive of all data types, from molecular sequences to morphology measurements and other supporting information. Access to soil biodiversity species records and information will be instrumental to progressing scientific research and education. Further, as demonstrated by previous biodiversity synthesis efforts, data availability is key for adapting to, and creating mitigation plans in response to global changes. With the rapid influx of soil biodiversity data, now is the time to take the first steps forward in establishing a global soil biodiversity information platform
The influence of the political environment and destination governance on sustainable tourism development: a study of Bled, Slovenia
In the context of sustainable tourism development, there are many studies about the exchange process between residents and tourism, yet this issue is practically unexplored with respect to the political environment of tourism. Therefore, this paper introduces and posits that the political environment is a necessary enabler for implementing sustainable tourism. The authors extend the established three-pillar sustainability concept by adding in the political dimension. Then they surveyed how residents' positive and negative perceptions of tourism impacts determine their satisfaction with life in the tourism destination and thus their support for tourism in their community. The model was empirically tested within the context of the long-established Alpine destination of Bled in Slovenia. The findings confirm the importance of the political environment and question the sustainability of Bled's tourism development. It is suggested that the community has relatively weak destination governance due to the underdeveloped political environment. The survey expands and deepens the tourism sustainability debate by adding in the political environment and how it relates to the emerging growth of research on destination governance. The proposed model can be adapted and applied to any destination in order to improve its governance, including the implementation of sustainable tourism development
Continuously improving the practice of cardiology
Guidelines for the management of patients with
cardiovascular disease are designed to assist
cardiologists and other physicans in their practice.
Surveys are conducted to assess whether guidelines
are followed in practice. The results of surveys on
acute coronary syndromes, coronary revascularisation,
secondary prevention, valvular heart disease
and heart failure are presented. Comparing surveys
conducted between 1995 and 2002, a gradual improvement
in use ofsecondary preventive therapy
is observed. Nevertheless, important deviations
from established guidelines are noted, with a
significant variation among different hospitals in
the Netherlands and in other European countries.
Measures for fiuther improvement of clinical
practice indude more rapid treatment of patients
with evolving myocardial infarction, more frequent
use of clopidogrel and glycoprotein IIb/IIIa
receptor blockers in patients with acute coronary
syndromes, more frequent use of 5-blockers in
patients with heart failure and more intense
measures to encourage patients to stop smoking.
Targets for the proportion ofpatients who might
receive specific therapies are presented
- …