Spin correlations in the electron-doped high-transition-temperature superconductor Nd{2-x}Ce{x}CuO{4+/-delta}

High-transition-temperature (high-Tc) superconductivity develops near antiferromagnetic phases, and it is possible that magnetic excitations contribute to the superconducting pairing mechanism. To assess the role of antiferromagnetism, it is essential to understand the doping and temperature dependence of the two-dimensional antiferromagnetic spin correlations. The phase diagram is asymmetric with respect to electron and hole doping, and for the comparatively less-studied electron-doped materials, the antiferromagnetic phase extends much further with doping [1, 2] and appears to overlap with the superconducting phase. The archetypical electron-doped compound Nd{2-x}Ce{x}CuO{4\pm\delta} (NCCO) shows bulk superconductivity above x \approx 0.13 [3, 4], while evidence for antiferromagnetic order has been found up to x \approx 0.17 [2, 5, 6]. Here we report inelastic magnetic neutron-scattering measurements that point to the distinct possibility that genuine long-range antiferromagnetism and superconductivity do not coexist. The data reveal a magnetic quantum critical point where superconductivity first appears, consistent with an exotic quantum phase transition between the two phases [7]. We also demonstrate that the pseudogap phenomenon in the electron-doped materials, which is associated with pronounced charge anomalies [8-11], arises from a build-up of spin correlations, in agreement with recent theoretical proposals [12, 13].Comment: 5 pages, 4 figure

Fine structure of alpha decay in odd nuclei

Using an alpha decay level scheme, an explanation for the fine structure in odd nuclei is evidenced by taking into account the radial and rotational couplings between the unpaired nucleon and the core of the decaying system. It is stated that the experimental behavior of the alpha decay fine structure phenomenon is directed by the dynamical characteristics of the system.Comment: 8 pages, 3 figures, REVTex, submitted to Physical Review

LYCOPENE AND THE ROLE IN METABOLIC PREVENTION

The origin of the tomato plant seems to be South America, in particular Chile and Ecuador, where it grows as a wild plant due to the tropical climate and is able to bear fruit throughout the year, while in European regions, if cultivated in 'open, has a seasonal cycle limited to the summer period. From here, it later spread to Central America and it was the Spaniards who made it known in Europe in the 16th century. Only at the end of the 18th century, the cultivation of tomatoes for food purposes experienced a strong boost in Europe, mainly in France and Southern Italy. Starting from the 19th century, the tomato was finally included in European gastronomic treaties, favoring a conspicuous diffusion both on the tables of the richest and those of the less well-off. Today tomatoes are a staple of our diet a series of researches have identified the effects that the consumption of this particular food, in its many variations, has on our health. If previously the effects that tomatoes have on the improvement of blood lipids were recognized, now researchers have identified a direct correlation between the risk of cardiovascular mortality and the consumption of the fruit, for the presence of Lycopene, a carotenoid antioxidant. It is lycopene, in particular, that produces the greatest benefits for our body. It is a powerful antioxidant that determines, among other things, the particular red color of the tomato. Through research on the effects of a diet rich in tomatoes on the body, the experts found a progressive decrease in the concentration of cholesterol accompanied by a decrease in cardiovascular risk

HEALTH PROPERTIES OF LYCOPERSICUM ESCULENTUM

The tomato, Lycopersicum esculentum, is a horticultural plant belonging to the Solanaceae family. In Italy, the term "tomato" is found for the first time in the famous "Herbarius" by Pietro Mattioli. The etymology of the name leads back to the Latin "pomum aureus", apple or golden apple. Unlike in other languages, such as English, the term "tomato" is linked to the etymology of the Aztec version "Xitotomate". The origin of the tomato plant seems to be South America, in particular Chile and Ecuador, where it grows as a wild plant due to the tropical climate and is able to bear fruit throughout the year, while in European regions, if cultivated in 'open, has a seasonal cycle limited to the summer period. From here, it later spread to Central America and it was the Spaniards who made it known in Europe in the 16th century. The cultivation of the tomato plant was already widespread in the pre-Columbian age, when it was used as an ornamental plant and was not used in the kitchen: this is because the tomato was considered poisonous due to its high content in solanine, a substance considered harmful for the 'man. In 1544, the Italian herbalist Pietro Mattioli classified the tomato plant among the poisonous species. It is not clear when the tomato, as an ornamental and poisonous plant, was considered edible by Europeans; it should be noted that not even the inhabitants of South America ate the fruits of the plant. From Europe, or perhaps more precisely from Spain, the tomato plant landed in Morocco, where it found an ideal climate, and from there it spread throughout the Mediterranean basin. Starting from the seventeenth century, in southern Europe, as well as in Bohemia and England, the tomato began to be used fresh and for the preparation of sauces, while its diffusion as a food in northern Europe encountered many difficulties, perhaps due to the presence of other similar wild plants which, due to their high alkaloid content, were not suitable for food consumption. Only at the end of the 18th century, the cultivation of tomatoes for food purposes experienced a strong boost in Europe, mainly in France and Southern Italy. Starting from the 19th century, the tomato was finally included in European gastronomic treaties, favoring a conspicuous diffusion both on the tables of the richest and those of the less well-off

Subthreshold K+ production in deuteron and alpha induced nuclear reactions

Double differential cross sections have been measured for pi+ and K+ emitted around midraidity in d+A and He+A collisions at a beam kinetic energy of 1.15 GeV/nucleon. The total pi+ yield increases by a factor of about 2 when using an alpha projectile instead of a deuteron whereas the K+ yield increases by a factor of about 4. According to transport calculations, the K+ enhancement depends both on the number of hadron-hadron collisions and on the energy available in those collisions: their center-of-mass energy increases with increasing number of projectile nucleons

Production of Charged Pions, Kaons and Antikaons in Relativistic C+C and C+Au Collisions

Production cross sections of charged pions, kaons and antikaons have been measured in C+C and C+Au collisions at beam energies of 1.0 and 1.8 AGeV for different polar emission angles. The kaon and antikaon energy spectra can be described by Boltzmann distributions whereas the pion spectra exhibit an additional enhancement at low energies. The pion multiplicity per participating nucleon M(pi+)/A_part is a factor of about 3 smaller in C+Au than in C+C collisions at 1.0 AGeV whereas it differs only little for the C and the Au target at a beam energy of 1.8 AGeV. The K+ multiplicities per participating nucleon M(K+)/A_part are independent of the target size at 1 AGeV and at 1.8 AGeV. The K- multiplicity per participating nucleon M(K-)/A_part is reduced by a factor of about 2 in C+Au as compared to C+C collisions at 1.8 AGeV. This effect might be caused by the absorption of antikaons in the heavy target nucleus. Transport model calculations underestimate the K-/K+ ratio for C+C collisions at 1.8 AGeV by a factor of about 4 if in-medium modifications of K mesons are neglected.Comment: 19 pages, 14 figures, accepted for publication in Eur. Phys. J.

Phase Decomposition and Chemical Inhomogeneity in Nd2-xCexCuO4

Extensive X-ray and neutron scattering experiments and additional transmission electron microscopy results reveal the partial decomposition of Nd2-xCexCuO4 (NCCO) in a low-oxygen-fugacity environment such as that typically realized during the annealing process required to create a superconducting state. Unlike a typical situation in which a disordered secondary phase results in diffuse powder scattering, a serendipitous match between the in-plane lattice constant of NCCO and the lattice constant of one of the decomposition products, (Nd,Ce)2O3, causes the secondary phase to form an oriented, quasi-two-dimensional epitaxial structure. Consequently, diffraction peaks from the secondary phase appear at rational positions (H,K,0) in the reciprocal space of NCCO. Additionally, because of neodymium paramagnetism, the application of a magnetic field increases the low-temperature intensity observed at these positions via neutron scattering. Such effects may mimic the formation of a structural superlattice or the strengthening of antiferromagnetic order of NCCO, but the intrinsic mechanism may be identified through careful and systematic experimentation. For typical reduction conditions, the (Nd,Ce)2O3 volume fraction is ~1%, and the secondary-phase layers exhibit long-range order parallel to the NCCO CuO2 sheets and are 50-100 angstromsthick. The presence of the secondary phase should also be taken into account in the analysis of other experiments on NCCO, such as transport measurements.Comment: 15 pages, 17 figures, submitted to Phys. Rev.