601 research outputs found
Cohomological Hasse principle and motivic cohomology for arithmetic schemes
In 1985 Kazuya Kato formulated a fascinating framework of conjectures which
generalizes the Hasse principle for the Brauer group of a global field to the
so-called cohomological Hasse principle for an arithmetic scheme. In this paper
we prove the prime-to-characteristic part of the cohomological Hasse principle.
We also explain its implications on finiteness of motivic cohomology and
special values of zeta functions.Comment: 47 pages, final versio
Inhomogeneity of the intrinsic magnetic field in superconducting YBa2Cu3OX compounds as revealed by rare-earth EPR-probe
X-band electron paramagnetic resonance on doped Er3+ and Yb3+ ions in
Y0.99(Yb,Er)0.01Ba2Cu3OX compounds with different oxygen contents in the wide
temperature range (4-120)K have been made. In the superconducting species, the
strong dependencies of the linewidth and resonance line position from the sweep
direction of the applied magnetic field are revealed at the temperatures
significantly below TC. The possible origins of the observed hysteresis are
analyzed. Applicability of the presented EPR approach to extract information
about the dynamics of the flux-line lattice and critical state parameters
(critical current density, magnetic penetration depth, and characteristic
spatial scale of the inhomogeneity) is discussedComment: 17 pages, 5 Figures. Renewed versio
THE EUROPEAN NUCLEAR EDUCATION NETWORK AND ITS ACTIONS IN FAVOUR OF EDUCATION, TRAINING, INFORMATION AND TRANSFER OF EXPERTISE
The European Nuclear Education Network (ENEN) Association is a non-profit organization established by the consortium of the EU 5th Framework Programme (FP) “ENEN” project in 2003. The ENEN Association started as a network of universities and research centers involved in education and training in nuclear engineering in EU countries and is presently involved in the challenging role of coordinating E&T in the nuclear fields in Europe. The main objective of ENEN is, in fact, the preservation and further development of expertise in the nuclear fields by higher education and training. Its members are now universities, research centers and industrial bodies established in European Countries; in addition, MoUs have been signed with several institutions and networks beyond the borders of European Union, thus reaching the number of more than 60 members. The objective of this paper is to provide an up to date view of the actions and plans of the Association in pursuing its missions
Effective and Efficient Similarity Index for Link Prediction of Complex Networks
Predictions of missing links of incomplete networks like protein-protein
interaction networks or very likely but not yet existent links in evolutionary
networks like friendship networks in web society can be considered as a
guideline for further experiments or valuable information for web users. In
this paper, we introduce a local path index to estimate the likelihood of the
existence of a link between two nodes. We propose a network model with
controllable density and noise strength in generating links, as well as collect
data of six real networks. Extensive numerical simulations on both modeled
networks and real networks demonstrated the high effectiveness and efficiency
of the local path index compared with two well-known and widely used indices,
the common neighbors and the Katz index. Indeed, the local path index provides
competitively accurate predictions as the Katz index while requires much less
CPU time and memory space, which is therefore a strong candidate for potential
practical applications in data mining of huge-size networks.Comment: 8 pages, 5 figures, 3 table
On the Whitehead spectrum of the circle
The seminal work of Waldhausen, Farrell and Jones, Igusa, and Weiss and
Williams shows that the homotopy groups in low degrees of the space of
homeomorphisms of a closed Riemannian manifold of negative sectional curvature
can be expressed as a functor of the fundamental group of the manifold. To
determine this functor, however, it remains to determine the homotopy groups of
the topological Whitehead spectrum of the circle. The cyclotomic trace of B
okstedt, Hsiang, and Madsen and a theorem of Dundas, in turn, lead to an
expression for these homotopy groups in terms of the equivariant homotopy
groups of the homotopy fiber of the map from the topological Hochschild
T-spectrum of the sphere spectrum to that of the ring of integers induced by
the Hurewicz map. We evaluate the latter homotopy groups, and hence, the
homotopy groups of the topological Whitehead spectrum of the circle in low
degrees. The result extends earlier work by Anderson and Hsiang and by Igusa
and complements recent work by Grunewald, Klein, and Macko.Comment: 52 page
Fine sediment reduces vertical migrations of Gammarus pulex (Crustacea: Amphipoda) in response to surface water loss
Surface and subsurface sediments in river ecosystems are recognized as refuges that may promote invertebrate survival during disturbances such as floods and streambed drying. Refuge use is spatiotemporally variable, with environmental factors including substrate composition, in particular the proportion of fine sediment (FS), affecting the ability of organisms to move through interstitial spaces. We conducted a laboratory experiment to examine the effects of FS on the movement of Gammarus pulex Linnaeus (Crustacea: Amphipoda) into subsurface sediments in response to surface water loss. We hypothesized that increasing volumes of FS would impede and ultimately prevent individuals from migrating into the sediments. To test this hypothesis, the proportion of FS (1–2 mm diameter) present within an open gravel matrix (4–16 mm diameter) was varied from 10 to 20% by volume in 2.5% increments. Under control conditions (0% FS), 93% of individuals moved into subsurface sediments as the water level was reduced. The proportion of individuals moving into the subsurface decreased to 74% at 10% FS, and at 20% FS no individuals entered the sediments, supporting our hypothesis. These results demonstrate the importance of reducing FS inputs into river ecosystems and restoring FS-clogged riverbeds, to promote refuge use during increasingly common instream disturbances
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