Experimental test of an alignment-sensing scheme for a gravitational-wave interferometer

An alignment-sensing scheme for all significant angular degrees of freedom of a power-recycled Michelson interferometer with Fabry Perot cavities in the arms was tested on a tabletop interferometer. The response to misalignment of all degrees of freedom was measured at each sensor, and good agreement was found between measured and theoretical values

Real space investigation of structural changes at the metal-insulator transition in VO2

Synchrotron X-ray total scattering studies of structural changes in rutile VO2 at the metal-insulator transition temperature of 340 K reveal that monoclinic and tetragonal phases of VO2 coexist in equilibrium, as expected for a first-order phase transition. No evidence for any distinct intermediate phase is seen. Unbiased local structure studies of the changes in V--V distances through the phase transition, using reverse Monte Carlo methods, support the idea of phase coexistence and point to the high degree of correlation in the dimerized low-temperature structure. No evidence for short range V--V correlations that would be suggestive of local dimers is found in the metallic phase.Comment: 4 pages, 5 figure

Spin-induced symmetry breaking in orbitally ordered NiCr_2O_4 and CuCr_2O_4

At room temperature, the normal oxide spinels NiCr_2O_4 and CuCr_2O_4 are tetragonally distorted and crystallize in the I4_1/amd space group due to cooperative Jahn-Teller ordering driven by the orbital degeneracy of tetrahedral Ni$^{2+}$ ($t_2^4$) and Cu$^{2+}$ ($t_2^5$). Upon cooling, these compounds undergo magnetic ordering transitions; interactions being somewhat frustrated for NiCr_2O_4 but not for CuCr_2O_4. We employ variable-temperature high-resolution synchrotron X-ray powder diffraction to establish that at the magnetic ordering temperatures there are further structural changes, which result in both compounds distorting to an orthorhombic structure consistent with the Fddd space group. NiCr_2O_4 exhibits additional distortion, likely within the same space group, at a yet-lower transition temperature of $T$ = 30 K. The tetragonal to orthorhombic structural transition in these compounds appears to primarily involve changes in NiO_4 and CuO_4 tetrahedra

10. Influence of Container Color and Medium Depth on Avian Herbivory of Longleaf Pine Seed

Survey results from nursery managers have indicated avian herbivory as the leading cause of seed loss and germinant mortality in forest tree seedling nurseries in the southern United States. Reports indicate over $150,000 in lost revenue with a 1% seed loss. Shade cloths are typically used to prevent herbivory but can often exacerbate losses when birds become trapped underneath the cloth. In a previous research trial that investigated longleaf pine sowing methods and subsequent seedling development, it was observed that birds exclusively foraged on seeds sown in cavities filled to depths of five inches (operational depth) compared to those sown at depths of three inches. The goal of this research was to determine if container color and medium depth affected the level of avian herbivory during the germination phase. Longleaf pine seeds were sown in either black or white container cells filled to either three or five inches of growing medium for a total of four treatments. There were three repetitions (trays of 49 cells) for each treatment. Birds consumed 74% of seeds sown in full cavities compared to 36% of seeds in cavities filled to three inches. Seed loss was 20 percentage points higher in black cavities compared to white cavities. Consumption occurred faster in cells filled to five inches (majority in first five days). Determining patterns in seed loss by avian species will assist nursery managers with decisions on sowing techniques and container selection and will help eliminate economic losses

Embedding Security Functionality In Formal Specifications Of Requirements

The methodology in this paper will let designers specify the security properties defined through the functional families of the ISO/IEC 15408 Standard, graphic representations.  This blueprint will allow both business and technical participants, to discuss and refine a common solution.  It also serves as a roadmap, to guide the implementation process. We feel this can become a useful supporting methodology for the construction of effective security responses, because it ensures both the widest possible participation in the design process as well as the greatest degree of understanding.  The fact that the advice of the world’s experts is readily available and easy to use as a result of this process might also serve to make the mission to protect America’s information assets a little more effective

Total scattering descriptions of local and cooperative distortions in the oxide spinel (Mg,Cu)Cr2O4 with dilute Jahn-Teller ions

The normal spinel oxide MgCr2O4 is cubic at room temperature while the normal spinel CuCr2O4 is tetragonal as a consequence of the Jahn-Teller nature of Cu2+ on the tetrahedral sites. Despite different end-member structures, complete solid solutions of Mg_{1-x}Cu_xCr2O4 can be prepared that display a first-order structural transition with composition x = 0.43 at room temperature. Reverse Monte Carlo analysis of total neutron scattering on data acquired between 300 K and 15 K on samples with x = 0.10, 0.20, and 0.43 provides unbiased local and average structure descriptions of the samples, including an understanding of the transition from local Jahn-Teller distortions in the cubic phase to cooperative distortions that result in a tetragonal structure. Distributions of continuous symmetry measures help to understand and distinguish distorted and undistorted coordination around the tetrahedral site in the solid solutions. Magnetic exchange bias is observed in field-cooled hysteresis loops of samples with dilute Cu2+ concentration and in samples with tetragonal--cubic phase coexistence around 300 K.Comment: 10 pages, 14 figure