Cleaving-temperature dependence of layered-oxide surfaces

The surfaces generated by cleaving non-polar, two-dimensional oxides are often considered to be perfect or ideal. However, single particle spectroscopies on Sr2RuO4, an archetypal non-polar two dimensional oxide, show significant cleavage temperature dependence. We demonstrate that this is not a consequence of the intrinsic characteristics of the surface: lattice parameters and symmetries, step heights, atom positions, or density of states. Instead, we find a marked increase in the density of defects at the mesoscopic scale with increased cleave temperature. The potential generality of these defects to oxide surfaces may have broad consequences to interfacial control and the interpretation of surface sensitive measurements

Polar surface engineering in ultra-thin MgO(111)/Ag(111) -- possibility of metal-insulator transition and magnetism

A recent report [Kiguchi {\it et al.}, Phys. Rev. B {\bf 68}, 115402 (2003)] that the (111) surface of 5 MgO layers grown epitaxially on Ag(111) becomes metallic to reduce the electric dipole moment raises a question of what will happen when we have fewer MgO layers. Here we have revealed, first experimentally with electron energy-loss spectroscopy, that MgO(111) remains metallic even when one-layer thick, and theoretically with the density functional theory that the metallization should depend on the nature of the substrate. We further show, with a spin-density functional calculation, that a ferromagnetic instability may be expected for thicker films.Comment: 5 pages, 7 figure

Deploying homeland security technology

The success of each depends on how efficiently they implement new technologies. Although the White House and the Congress have responded swiftly to the events of September 11, 2001, the long-term security of our Nation, and thus the success of the newly created Department of Homeland Security, will depend in a substantial way on the efficiency with which technologies relevant to homeland security are created and, more importantly, deployed. The purpose of this paper is to assess the Administration's revealed understanding of the innovation process, which underlies the creation of new homeland security technology, and attendant factors that relate to the efficiency with which the new technology is deployed. By -revealed understanding‖ we are referring to the written word, namely what is outlined in the Homeland Security Act of 2002 and related documents. Certainly, the Act, and related document s from t he Whit e House, are only init ial templates that frame activities to come. But, as the Brookings Institution's (2002, p. i) early assessment of the Department 's organizat ion, and t he Depart ment 's organization is fundamentally related to its ability to provide incentives for the creation and deployment of homeland security technology, -... while it is possible to revisit or even reverse organizational decisions at a later stage, it is far better to get it right the first time.‖ The Department of Homeland Security will be charged with four primary tasks. The new agency will [1] control our borders and prevent terrorists and explosives from entering our country. It will [2] work with state and local authorities to respond quickly and effectively to emergencies. It will [3] bring together our best scientists to develop technologies that detect biological, chemical, and nuclear weapons, and to discover the drugs and treatments to best protect our citizens. And this new department will [4] review intelligence and law enforcement information from all agencies of government, and produce a single daily picture of threats against our homeland. An emphasis on homeland security technology One of the first policy institutes to offer an opinion on homeland security was the Heritage Foundation (2002). 2 Its report, Defending the American Homeland, recommended four well conceived priorities: protecting the Nation's infrastructures, strengthening civil defense, improving intelligence and law enforcement, and military operations to combat terrorism

Exchange bias and interface electronic structure in Ni/Co3O4(011)

A detailed study of the exchange bias effect and the interfacial electronic structure in Ni/Co3O4(011) is reported. Large exchange anisotropies are observed at low temperatures, and the exchange bias effect persists to temperatures well above the Neel temperature of bulk Co3O4, of about 40 K: to ~80 K for Ni films deposited on well ordered oxide surfaces, and ~150 K for Ni films deposited on rougher Co3O4 surfaces. Photoelectron spectroscopy measurements as a function of Ni thickness show that Co reduction and Ni oxidation occur over an extended interfacial region. We conclude that the exchange bias observed in Ni/Co3O4, and in similar ferromagnetic metallic/Co3O4 systems, is not intrinsic to Co3O4 but rather due to the formation of CoO at the interface.Comment: 8 pages, 6 figures. Accepted for publication in Physical Review B

Tests of silicon sensors for the CMS pixel detector

The tracking system of the CMS experiment, currently under construction at the Large Hadron Collider (LHC) at CERN (Geneva, Switzerland), will include a silicon pixel detector providing three spacial measurements in its final configuration for tracks produced in high energy pp collisions. In this paper we present the results of test beam measurements performed at CERN on irradiated silicon pixel sensors. Lorentz angle and charge collection efficiency were measured for two sensor designs and at various bias voltages.Comment: Talk presented at 6th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors, September 29-October 1, 2003, Firenze, Italy. Proceedings will be published in Nuclear Instr. & Methods in Phys. Research, Section

Induction of diapause in Drosophila melanogaster: photoperiodic regulation and the impact of arrhythmic clock mutations on time measurement.

The fruit fly Drosophila melanogaster displays an ovarian diapause that is regulated by photoperiod. Newly eclosed female flies (Canton-S wild type) exposed to short days (less than 14 hr of light per day) at 12 degrees C (or 10 degrees C) enter a fairly shallow reproductive diapause. Females exposed to long days (16 hr of light per day) at the same low temperature undergo ovarian maturation. The short day induced diapause continues for 6-7 weeks under a 10:14 light/dark cycle at 12 degrees C but is terminated rapidly after a transfer to higher temperature (18 or 25 degrees C) or to long days (18:6 light/dark cycle). Females from three strains homozygous for alleles of the period (per) locus, reportedly arrhythmic for behavioral circadian rhythms, and females that possessed two overlapping deletions of per were also capable of discriminating between long and short days, although, when compared with the wild-type flies, the critical day length was shifted to shorter values by approximately 2 hr. It is concluded that the period locus is not causally involved in photoperiod time measurement

Replacement of Palm Methyl Ester to Rapeseed Methyl Ester for Tar Removal in the Nong Bua Dual Fluidized Bed Gasification Power Plant

The blockage problem of tar in a biomass power plant is a main problem and it must be removed. Rapeseed methyl ester (RME) was imported and used as scrubbing solvent to scrub tar at a 1 MWel Nong Bua prototype Dual Fluidised Bed (DFB) gasifier in Nong Bua district, Nakhonsawan province, Thailand. Using local oil in Thailand is an attractive choice from economic viewpoint. Pervious lab test study on naphthalene solubility in different local oils in Thailand was investigated. Local palm methyl ester (PME) shows the competitive performance to the RME. In this research, PME was tested to scrub tar in an oil scrubber at the Nong Bua DFB gasifier plant. Gravimetric tar content after passed a PME scrubber was measured and compared to that from a RME oil scrubber. The results show that both solvents have similar tar removal performance due to their contents of ester, methanol, and glycerin are similar. In addition, viscosity of both solvents has no significant effect on tar removal. From the current research, therefore, PME has been used as solvent in an oil scrubber at 1 MWel Nong Bua prototype DFB gasifier with technical and economic reasons

Photoelectron diffraction investigation of the structure of the clean TiO2(110)(1×1) surface

The surface relaxations of the rutile TiO2(110)(1×1) clean surface have been determined by O 1 s and Ti 2p3∕2 scanned-energy mode photoelectron diffraction. The results are in excellent agreement with recent low-energy electron diffraction (LEED) and medium energy ion scattering (MEIS) results, but in conflict with the results of some earlier investigations including one by surface x-ray diffraction. In particular, the bridging O atoms at the surface are found to relax outward, rather than inward, relative to the underlying bulk. Combined with the recent LEED and MEIS results, a consistent picture of the structure of this surface is provided. While the results of the most recent theoretical total-energy calculations are qualitatively consistent with this experimental consensus, significant quantitative differences remain