7,417 research outputs found
Characterisation and textural analysis of Middle Bronze Age Transdanubian inlaid wares of the Encrusted Pottery Culture, Hungary: a preliminary study
Inlaid ceramics belonging to the Encrusted Pottery Culture and dated to the Middle Bronze Age (2000–1500 BC) are highly distinctive vessels with complex decorative motifs found in large numbers in the Transdanubia region of Hungary. Despite this considerable corpus of material there has been little systematic investigation of the composition of the inlays. Micro-analysis of Transdanubian inlaid wares by X-ray diffraction (XRD), micro-Fourier transform infrared microscopy (FT-IR), and scanning electron microscopy (SEM) provides new compositional, structural and textural information on the inlays. In contrast to common statements in the literature regarding the materials used to make inlays, these new data show that the majority of inlays are composed of hydroxyapatite (bone) that was previously ashed, although some of the inlays are composed of calcium carbonate. Additional compositional and textural variation in the bone inlays suggests that bone material from different skeletal elements and/or of different age may have been used, and that contrasting recipes for inlay preparation were employed during fabrication. These results suggest that the production of inlaid vessels of the Encrusted Pottery Culture was more complex than has hitherto been thought
Dynamical Equations from a First-Order Perturbative Superspace Formulation of 10D N=1 String-Corrected Supergravity (I)
Utilizing a first-order perturbative superspace approach, we derive the
bosonic equations of motion for the 10D, N = 1 supergravity fields. We give the
Lagrangian corresponding to these equations derived from superspace geometry.
Moreover, the equivalence of this Lagrangian to the first-order perturbative
component level Lagrangian of anomaly-free supergravity is proven. Our
treatment covers both the two-form and six-form formulations.Comment: 20 pages, no figures, references and note in proof adde
Teleportation: from probability distributions to quantum states
The role of the off-diagonal density matrix elements of the entangled pair is
investigated in quantum teleportation of a qbit. The dependence between them
and the off-diagonal elements of the teleported density matrix is shown to be
linear. In this way the ideal quantum teleportation is related to an entirely
classical communication protocol: the one-time pad cypher. The latter can be
regarded as the classical counterpart of Bennett's quantum teleportation
scheme. The quantum-to-classical transition is demonstrated on the statistics
of a gedankenexperiment.Comment: 11 pages, 1 figure, accepted for publication in J. Phys. A (Math.
Gen.
Ageing as a price of cooperation and complexity: Self-organization of complex systems causes the ageing of constituent networks
The analysis of network topology and dynamics is increasingly used for the description of the structure, function and evolution of complex systems. Here we summarize key aspects of the evolvability and robustness of the hierarchical network-set of macromolecules, cells, organisms, and ecosystems. Listing the costs and benefits of cooperation as a necessary behaviour to build this network hierarchy, we outline the major hypothesis of the paper: the emergence of hierarchical complexity needs cooperation leading to the ageing of the constituent networks. Local cooperation in a stable environment may lead to over-optimization developing an ‘always-old’ network, which ages slowly, and dies in an apoptosis-like process. Global cooperation by exploring a rapidly changing environment may cause an occasional over-perturbation exhausting system-resources, causing rapid degradation, ageing and death of an otherwise ‘forever-young’ network in a necrosis-like process. Giving a number of examples we explain how local and global cooperation can both evoke and help successful ageing. Finally, we show how various forms of cooperation and consequent ageing emerge as key elements in all major steps of evolution from the formation of protocells to the establishment of the globalized, modern human society. Thus, ageing emerges as a price of complexity, which is going hand-in-hand with cooperation enhancing each other in a successful community
Magnetic and Transport Properties of Fe-Ag granular multilayers
Results of magnetization, magnetotransport and Mossbauer spectroscopy
measurements of sequentially evaporated Fe-Ag granular composites are
presented. The strong magnetic scattering of the conduction electrons is
reflected in the sublinear temperature dependence of the resistance and in the
large negative magnetoresistance. The simultaneous analysis of the magnetic
properties and the transport behavior suggests a bimodal grain size
distribution. A detailed quantitative description of the unusual features
observed in the transport properties is given
Quantifying inter-field movements of the western corn rootworm (Diabrotica virgifera virgifera LeConte) — A Central European field study
Dispersal plays a key role in the adaptation of species. It has been suggested that even in a stable and predictable environment, it is essential for any given population to “send” a certain portion of its offspring to disperse (referred as evolutionary stable dispersal rate). Although the literature on the flight behaviour of one of the major maize pests, the western corn rootworm, is rich, relatively little is known about its inter-field movements under field conditions. In the present study, inter-field movement of adult beetles was observed in Central-Europe under quasi-isolated conditions of infested continuous and un-infested first year maize fields, and related to candidate predictor variables. Percent of immigrants (net percent of adults within a given population leaving their natal maize field and arriving in first-year maize) varied greatly across years and locations (0.4–93.3%, mean = 38.7%). Results of the study provided field evidence of the assumption that western corn rootworm performs density dependent inter-field movement. Independent from pest densities, it appeared that about 1/3 of an adult beetle population always leaves its natal maize field, which likely allows the species to find new food sources and oviposition sites. The distance between maize fields and the phenological status of maize influenced inter-field movements but at a much less extent than it could have been expected from laboratory research findings
N=4 central charge superspace at work for supergravity coupled to an arbitrary number of abelian vector multiplets
We present the description in central charge superspace of N=4 supergravity
with antisymmetric tensor coupled to an arbitrary number of abelian vector
multiplets. All the gauge vectors of the coupled system are treated on the same
footing as gauge fields corresponding to translations along additional bosonic
coordinates. It is the geometry of the antisymmetric tensor which singles out
which combinations of these vectors belong to the supergravity multiplet and
which are the additional coupled ones. Moreover, basic properties of
Chapline-Manton coupling mechanism, as well as the SO(6,n)/SO(6)*SO(n) sigma
model of the Yang-Mills scalars are found as arising from superspace geometry.Comment: 18 page
Measurement induced chaos with entangled states
The dynamics of an ensemble of identically prepared two-qubit systems is
investigated which is subjected to the iteratively applied measurements and
conditional selection of a typical entanglement purification protocol. It is
shown that the resulting measurement-induced non-linear dynamics of the
two-qubit state exhibits strong sensitivity to initial conditions and also true
chaos. For a special class of initially prepared two-qubit states two types of
islands characterize the asymptotic limit. They correspond to a separable and a
maximally entangled two-qubit state, respectively, and their boundaries form
fractal-like structures. In the presence of incoherent noise an additional
stable asymptotic cycle appears.Comment: 5 pages, 3 figure
Tailoring Fe/Ag Superparamagnetic Composites by Multilayer Deposition
The magnetic properties of Fe/Ag granular multilayers were examined by SQUID
magnetization and Mossbauer spectroscopy measurements. Very thin (0.2 nm)
discontinuous Fe layers show superparamagnetic properties that can be tailored
by the thickness of both the magnetic and the spacer layers. The role of
magnetic interactions was studied in novel heterostructures of
superparamagnetic and ferromagnetic layers and the specific contribution of the
ferromagnetic layers to the low field magnetic susceptibility was identified.Comment: 5 pages and 3 figure
New iron-based Heusler compounds Fe2YZ: Comparison with theoretical predictions of the crystal structure and magnetic properties
The present work reports on the new soft ferromagnetic Heusler phases
Fe2NiGe, Fe2CuGa, and Fe2CuAl, which in previous theoretical studies have been
predicted to exist in a tetragonal regular Heusler structure. Together with the
known phases Fe2CoGe and Fe2NiGa these materials have been synthesized and
characterized by powder XRD, 57 Fe M\"ossbauer spectroscopy, SQUID and EDX
measurements. In particular M\"ossbauer spectroscopy was used to monitor the
degree of local atomic order/disorder and to estimate magnetic moments at the
Fe sites from the hyperfine fields. It is shown that in contrast to the
previous predictions all the materials except Fe2NiGa basically adopt the
inverse cubic Heusler (X-) structure with differing degrees of disorder. The
disorder is more enhanced in case of Fe2NiGa, which was predicted as an inverse
Heusler phase. The experimental data are compared with results from ab-inito
electronic structure calculations on LDA level incorporating the effects of
atomic disorder by using the coherent potential approximation (CPA). A good
agreement between calculated and experimental magnetic moments is found for the
cubic inverse Heusler phases. Model calculations on various atomic
configurations demonstrate that antisite disorder tends to enhance the
stability of the X-structure. Given the fundamental scientific and
technological importance of tetragonal Heusler phases the present results call
for further investigations to unravel the factors stabilizing tetragonal
Heusler materials
- …