Water does partially dissociate on the perfect TiO2(110) surface : a quantitative structure determination

There has been a long-standing controversy as to whether water can dissociate on perfect areas of a TiO2(110) surface; most early theoretical work indicated this dissociation was facile, while experiments indicated little or no dissociation. More recently the consensus of most theoretical calculations is that no dissociation occurs. New results presented here, based on analysis of scanned-energy mode photoelectron diffraction data from the OH component of O 1s photoemission, show the coexistence of molecular water and OH species in both atop (OHt) and bridging (OHbr) sites. OHbr can arise from reaction with oxygen vacancy defect sites (Ovac), but OHt have only been predicted to arise from dissociation on the perfect areas of the surface. The relative concentrations of OHt and OHbr sites arising from these two dissociation mechanisms are found to be fully consistent with the initial concentration Ovac sites, while the associated Ti-O bondlengths of the OHt and OHbr species are found to be 1.85±0.08Å and 1.94±0.07 Å, respectively

ECONOMIC FEASIBILITY OF THE CATTLE FEEDING INDUSTRY IN THE NORTHERN PLAINS AND WESTERN LAKES STATES - SUMMARY

The five-state study area of the Northern Plains and Western Lakes States, Minnesota, Montana, North Dakota, South Dakota, and Wisconsin, has adequate feed supplies and feeder cattle to markedly increase cattle feeding. Feed costs in these states have historically been lower than in the Southern Plains States. However, higher transportation costs appear to offset that advantage. Close access to slaughter plants in these states could offset that transportation disadvantage. Backgrounding of cattle appears to be quite profitable and cattle feeding, especially in larger sized feedlots, can be profitable. However, the cattle feeding industry has an increasing level of excess capacity. To be successful, new feedlots in the Northern Plains and Western Lakes States would need cost efficiencies to offset higher production costs, compared to Nebraska and Kansas, or would need to produce for a niche market unaffected by the lower operating costs of already established feedlots in the Central and Southern Plains States. Finally, a range of strategies are available in developing value-added cattle production in the Northern Plains and Western Lakes States. These strategies embody differing levels of capital investment, and involve different levels of risk and profitability.cattle feeding, Northern Plains, economies of scale, cooperative ownership, entrance strategies, Production Economics,

Choptuik scaling in six dimensions

We perform numerical simulations of the critical gravitational collapse of a spherically symmetric scalar field in 6 dimensions. The critical solution has discrete self-similarity. We find the critical exponent \gamma and the self-similarity period \Delta.Comment: 8 pages, 3 figures RevTe

A photoelectron diffraction investigation of vanadyl phthalocyanine on Au(1 1 1)

Scanned-energy mode photoelectron diffraction using the O 1s and V 2p emission perpendicular to the surface has been used to investigate the orientation and internal conformation of vanadyl phthalocyanine (VOPc) adsorbed on Au(1 1 1). The results confirm earlier indications from scanning tunnelling microscopy that the Vdouble bond; length as m-dashO vanadyl bond points out of, and not into, the surface. The Vdouble bond; length as m-dashO bondlength is 1.60 ± 0.04 Å, not significantly different from its value in bulk crystalline VOPc. However, the V atom in the adsorbed molecule is almost coplanar with the surrounding N atoms and is thus pulled down into the approximately planar region defined by the N and C atoms by 0.52 (+0.14/−0.10) Å, relative to its location in crystalline VOPc. This change must be attributed to the bonding interaction between the molecule and the underlying metal surface

Phase Gradient Algorithm Method for 3-D Holographic Ladar Imaging

3-D holographic ladar uses digital holography with frequency diversity to add the ability to resolve targets in range. A key challenge is that since individual frequency samples are not recorded simultaneously, differential phase aberrations may exist between them making it difficult to achieve range compression. We describe steps specific to this modality so that phase gradient algorithms (PGA) can be applied to 3-D holographic ladar data for phase corrections across multiple temporal frequency samples. Substantial improvement of range compression is demonstrated with a laboratory experiment where our modified PGA technique is applied. Additionally, the PGA estimator is demonstrated to be efficient for this application and the maximum entropy saturation behavior of the estimator is analytically described

Collapse of a Circular Loop of Cosmic String

We study the collapse of a circular loop of cosmic string. The gravitational field of the string is treated using the weak field approximation. The gravitational radiation from the loop is evaluated numerically. The memtric of the loop near the point of collapse is found analytically.Comment: 15 page

Quantitative adsorbate structure determination under catalytic reaction conditions

Current methods allow quantitative local structure determination of adsorbate geometries on surfaces in ultrahigh vacuum (UHV) but are incompatible with the higher pressures required for a steady-state catalytic reactions. Here we show that photoelectron diffraction can be used to determine the structure of the methoxy and formate reaction intermediates during the steady-state oxidation of methanol over Cu(110) by taking advantage of recent instrumental developments to allow near-ambient pressure x-ray photoelectron spectroscopy. The local methoxy site differs from that under static UHV conditions, attributed to the increased surface mobility and dynamic nature of the surface under reaction conditions

Drawing Trees with Perfect Angular Resolution and Polynomial Area

We study methods for drawing trees with perfect angular resolution, i.e., with angles at each node v equal to 2{\pi}/d(v). We show: 1. Any unordered tree has a crossing-free straight-line drawing with perfect angular resolution and polynomial area. 2. There are ordered trees that require exponential area for any crossing-free straight-line drawing having perfect angular resolution. 3. Any ordered tree has a crossing-free Lombardi-style drawing (where each edge is represented by a circular arc) with perfect angular resolution and polynomial area. Thus, our results explore what is achievable with straight-line drawings and what more is achievable with Lombardi-style drawings, with respect to drawings of trees with perfect angular resolution.Comment: 30 pages, 17 figure

Keck Spectroscopy and HST Imaging of Field Galaxies at Moderate Redshift

We present 18 spectra, obtained with the Keck 10m telescope, of faint field galaxies (19 $<$ I $<$ 22, 0.2 $<$ z $<$ 0.84) previously imaged by {\it HST's} WFPC2. Though small, our sample appears to be representative of field spirals with a magnitude--limit of I $\le$ 22. Combining the results from the spectral and imaging data, we have derived various quantitative parameters for the galaxies, including colors, inclinations, emission line equivalent widths, redshifts, luminosities, internal velocity information and physical scale lengths. In particular, disk scale lengths (with sizes ranging from $\sim$1--5 kpc) have been measured from fits to the surface brightness profiles. We have also measured internal velocities with a rest frame resolution of $\sigma$ = 55 to 80 km s$^{-1}$ by fitting to the emission lines. The luminosity--disk size and luminosity--internal velocity (Tully--Fisher) relations for our moderate redshift galaxies are similar to the scaling relations seen for local galaxies, albeit with a modest brightening of $\sim$1 magnitude. The one bulge--dominated galaxy in our sample (at z = 0.324) has a relatively blue color, reveals weak emission lines and is $\sim$0.5 magnitude brighter in the rest frame than expected for a passive local elliptical. Our data suggest that galaxies at about half the age of the Universe have undergone mild luminosity evolution to the present epoch, but are otherwise quantitatively similar to galaxies seen locally.Comment: replaced short version of paper. 31 pages, figures and tables available at http://www.ucolick.org/~forbes/home.htm

Femoroacetabular Impingement as a Complication of Acetabular Fracture Fixation

Case We present the case of a thirteen-year-old female who sustained a posterior wall acetabular fracture dislocation. She underwent urgent closed reduction and subsequent uncomplicated open reduction and internal fixation. Post reduction computed tomography demonstrated a concentrically reduced hip joint with no evidence of femoroacetabular impingement (FAI). She subsequently healed her fracture and returned to running activities; however, one year later presented with aching pain in her thigh. Radiographs demonstrated the development of a large osseous prominence on her anterolateral femoral neck consistent with femoroacetabular impingement. Based on these findings she was evaluated by a hip preservation specialist. She subsequently underwent successful hip arthroscopy for labral repair and femoral osteochondroplasty. She was eventually able to return to running sports with little pain. Summary We present a case of FAI presenting as a complication of acetabular fracture fixation. This should be discussed with patients presenting with traumatic hip dislocations as a possible complication of surgical fixation or possibly of the injury itself