Spin Versus Charge Density Wave Order in Graphene-like Systems

A variational technique is used to study sublattice symmetry breaking by strong on-site and nearest neighbor interactions in graphene. When interactions are strong enough to break sublattice symmetry, and with relative strengths characteristic of graphene, a charge density wave Mott insulator is favored over the spin density wave condensates. In the spin density wave condensate we find that introduction of a staggered on-site energy (quasiparticle mass) leads to a splitting of the fermi velocities and mass gaps of the quasiparticle spin states.Comment: 5 pages, 4 figures; some comments adde

^{115}In-NQR evidence for unconventional superconductivity in CeIn_3 under pressure

We report evidence for unconventional superconductivity in CeIn_3 at a pressure P = 2.65 GPa above critical pressure (P_c ~ 2.5 GPa) revealed by the measurements of nuclear-spin-lattice-relaxation time (T_1) and ac-susceptibility (ac-chi). Both the measurements of T_1 and ac-chi have pointed to a superconducting transition at T_c = 95 mK, which is much lower than an onset temperature T_{onset} = 0.15 K at zero resistance. The temperature dependence of 1/T_1 shows no coherence peak just below T_c, indicative of an unconventional nature for the superconductivity induced in CeIn_3.Comment: 4 pages, 4 figures, to be published in Phys.Rev.

Uniform Mixing of High-Tc Superconductivity and Antiferromagnetism on a Single CuO2 Plane in Hg-based Five-layered Cuprate

We report a site selective Cu-NMR study on under-doped Hg-based five-layered high-$T_{\rm c}$ cuprate HgBa2Ca4Cu5Oy with a Tc=72 K. Antiferromagnetism (AF) has been found to take place at TN=290 K, exhibiting a large antiferromagnetic moment of 0.67-0.69uB at three inner planes (IP's). This value is comparable to the values reported for non-doped cuprates, suggesting that the IP may be in a nearly non-doped regime. Most surprisingly, the AF order is also detected with M(OP)=0.1uB even at two outer planes (OP's) that are responsible for the onset of superconductivity (SC). The high-Tc SC at Tc = 72 K can uniformly coexist on a microscopic level with the AF at OP's. This is the first microscopic evidence for the uniform mixed phase of AF and SC on a single CuO2 plane in a simple environment without any vortex lattice and/or stripe order.Comment: 4 pages, 4 figures. To be published in Phys.Rev.Let

Multi-focal Disturbances of the Postischemic Rat Brain by Measuring Blood Flow, Glucose Metabolism and Adenosine A1 Binding Activity

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To synchronize or not to synchronize, that is the question: finite-size scaling and fluctuation effects in the Kuramoto model

The entrainment transition of coupled random frequency oscillators presents a long-standing problem in nonlinear physics. The onset of entrainment in populations of large but finite size exhibits strong sensitivity to fluctuations in the oscillator density at the synchronizing frequency. This is the source for the unusual values assumed by the correlation size exponent $\nu'$. Locally coupled oscillators on a $d$-dimensional lattice exhibit two types of frequency entrainment: symmetry-breaking at $d > 4$, and aggregation of compact synchronized domains in three and four dimensions. Various critical properties of the transition are well captured by finite-size scaling relations with simple yet unconventional exponent values.Comment: 9 pages, 1 figure, to appear in a special issue of JSTAT dedicated to Statphys2

Monte Carlo Simulation of X-Ray Spectra from Rh- and Cu-Targets Generated by kV-Electrons

Monte Carlo simulation is applied to calculate X-ray generation in thick targets under kV electron bombardment. As a preliminary examination, we adopted the simple model based on the uses of: (1) screened Rutherford scattering formula and Bethe\u27s stopping power for describing elastic scattering and energy loss process of penetrating electrons, respectively, (2) Burhop\u27s ionization-cross-section and Sommerfeld\u27s Bremsstrahlung equation for generation of characteristic and continuous X-rays, respectively. In the Monte Carlo simulation, however, more practical expressions were used for convenience of calculation to describe generation of X-rays. To see how precisely this Monte Carlo simulation describes X-ray spectrum generated in a thick target, we applied this approach to X-ray generation in Rh-and Cu-targets under bombardment by 50kV and 20kV electrons, respectively, to compare with experimental results. This comparison has led to the conclusion that the present Monte Carlo simulation describes general tendency of X-ray spectra from the Rh-and Cu-targets with considerable success although the simulation tends to underestimate the X-rays intensity at long wave length

Rubble Stone Masonry Buildings With Cement Mortar: Design Specifications in Seismic and Masonry Codes Worldwide

Nearly 325 seismic and masonry codes from all over the world have been analyzed, of countries where stone masonry was, or still is, abundantly practiced. This paper compares and summarizes design specifications and construction requirements, with a specific focus on “nominally reinforced rubble stone masonry (NRM) with cement mortar and wooden diaphragms in seismic areas.” Currently, the technique is only allowed and described in some detail in the codes of Nepal, India, China, Tajikistan, Georgia, Iran and Croatia. It is concluded that the design specifications vary greatly without any consensus on the main sizes, dimensions or details. This raises questions about the completeness and correctness, as well as the reliability and actual value of the knowledge in this field. It is further observed that types of stone masonry and stone properties are seldom clearly described in the codes. It is also noted that several countries where stone masonry is still broadly practiced, are currently not allowing the technique (or have no codes in place), such as Afghanistan, Pakistan, Bhutan, Azerbaijan, Kyrgyzstan, Morocco, Tunisia, Turkey, Yemen and Albania. This, however, does not serve the current engineering practices and construction needs in these countries. To address all shortcomings, the paper recommends clear descriptions and terminology; the international adaption of NRM as a fourth masonry category; and the development of a stand-alone code specifically for this technique. Therefore, the authors propose a full assessment, validation, optimization and complementation of the existing knowledge, by means of the current state-of-the-art for calculating, testing and modeling. This envisions a structured research approach with focus on vernacular and traditional construction techniques, called “Non-Engineered 2.0,” for which a research initiative is started under the name “SMARTnet,” meaning “Seismic Methodologies for Applied Research and Testing of non-engineered techniques.” The findings of this paper will serve as the starting point for the upcoming follow-up paper, which will complement the seismic demand with hand-made base shear calculations for countries that still allow the technique. The paper ends with an appeal to experts, academics and final-year students worldwide, to exchange their knowledge and to support the project with their time and expertise