Preliminary analysis of LDEF instrument A0187-1: Chemistry of Micrometeoroids Experiment

The Chemistry of Micrometeoroids Experiment (CME) exposed approximately 0.8 sq. m of gold on the Long Duration Exposure Facility's (LDEF's) trailing edge (location A03) and approximately 1.1 sq. m of aluminum in the forward-facing A11 location. The most significant results to date relate to the discovery of unmelted pyroxene and olivine fragments associated with natural cosmic dust impacts. The latter are sufficiently large for detailed phase studies, and they serve to demonstrate that recovery of unmelted dust fragments is a realistic prospect for further dust experiments that will employ more advanced collector media. We also discovered that man-made debris impacts occur on the LDEF's trailing edge with substantially higher frequency than expected, suggesting that orbital debris in highly elliptical orbits may have been somewhat underestimated

The Survival Benefit of Liver Transplantation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73611/1/j.1600-6143.2004.00703.x.pd

Transplanting Kidneys Without Points for HLA‐B Matching: Consequences of the Policy Change

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87103/1/j.1600-6143.2011.03606.x.pd

Does the Indication for Breast Surgery Impact Surgical Outcomes? A Contemporary Analysis of the ACS-NSQIP Database

Background. There is limited data about whether perioperative outcomes differ based on the indication for breast surgery. Herein we aim to assess if breast surgery for prophylaxis, compared to that for malignancy, impacts surgical outcomes. Methods. All women who underwent simple or subcutaneous mastectomy were identified from the 2007-2012 ACS-NSQIP database. Patients were identified by their ICD-9 codes and categorized into two groups. Group 1 consisted of patients diagnosed with breast cancer or carcinoma in situ; group 2 consisted of patients diagnosed with a genetic predisposition to malignant neoplasm of the breast (i.e., BRCA mutation). Demographic and preoperative variables were compared between groups and outcome variables. Outcome variables were analyzed using age- and operative time-adjusted logistic regression models. Results. 30,803 patients were identified. Group 1 consisted of 30,644 (99.5%) patients diagnosed with malignancy; group 2 consisted of 159 (0.5%) who underwent prophylactic surgery. In univariate analyses, those undergoing prophylactic surgery were significantly younger (p \u3c 0.01). There were no other preoperative differences between groups. When adjusted, the prophylactic group demonstrated a greater risk of DVT (p = 0.03). There were no differences in mortality, superficial/deep/organ space infections, UTI, wound dehiscence, or MI. Conclusion. In this analysis of a national cohort of breast surgery patients, those undergoing prophylactic surgery due to a genetic predisposition had a greater risk of perioperative DVT, compared to those who underwent surgery for a diagnosis of malignancy. This data may allow for improved perioperative management of patients to prevent DVT development and their devastating consequences

A Higher Dimensional Stationary Rotating Black Hole Must be Axisymmetric

A key result in the proof of black hole uniqueness in 4-dimensions is that a stationary black hole that is ``rotating''--i.e., is such that the stationary Killing field is not everywhere normal to the horizon--must be axisymmetric. The proof of this result in 4-dimensions relies on the fact that the orbits of the stationary Killing field on the horizon have the property that they must return to the same null geodesic generator of the horizon after a certain period, $P$. This latter property follows, in turn, from the fact that the cross-sections of the horizon are two-dimensional spheres. However, in spacetimes of dimension greater than 4, it is no longer true that the orbits of the stationary Killing field on the horizon must return to the same null geodesic generator. In this paper, we prove that, nevertheless, a higher dimensional stationary black hole that is rotating must be axisymmetric. No assumptions are made concerning the topology of the horizon cross-sections other than that they are compact. However, we assume that the horizon is non-degenerate and, as in the 4-dimensional proof, that the spacetime is analytic.Comment: 24 pages, no figures, v2: footnotes and references added, v3: numerous minor revision

Geometric reconstruction methods for electron tomography

Electron tomography is becoming an increasingly important tool in materials science for studying the three-dimensional morphologies and chemical compositions of nanostructures. The image quality obtained by many current algorithms is seriously affected by the problems of missing wedge artefacts and nonlinear projection intensities due to diffraction effects. The former refers to the fact that data cannot be acquired over the full $180^\circ$ tilt range; the latter implies that for some orientations, crystalline structures can show strong contrast changes. To overcome these problems we introduce and discuss several algorithms from the mathematical fields of geometric and discrete tomography. The algorithms incorporate geometric prior knowledge (mainly convexity and homogeneity), which also in principle considerably reduces the number of tilt angles required. Results are discussed for the reconstruction of an InAs nanowire

Nonequilibrium spectral diffusion due to laser heating in stimulated photon echo spectroscopy of low temperature glasses

A quantitative theory is developed, which accounts for heating artifacts in three-pulse photon echo (3PE) experiments. The heat diffusion equation is solved and the average value of the temperature in the focal volume of the laser is determined as a function of the 3PE waiting time. This temperature is used in the framework of nonequilibrium spectral diffusion theory to calculate the effective homogeneous linewidth of an ensemble of probe molecules embedded in an amorphous host. The theory fits recently observed plateaus and bumps without introducing a gap in the distribution function of flip rates of the two-level systems or any other major modification of the standard tunneling model.Comment: 10 pages, Revtex, 6 eps-figures, accepted for publication in Phys. Rev.

DNA-based Self-Assembly of Chiral Plasmonic Nanostructures with Tailored Optical Response

Surface plasmon resonances generated in metallic nanostructures can be utilized to tailor electromagnetic fields. The precise spatial arrangement of such structures can result in surprising optical properties that are not found in any naturally occurring material. Here, the designed activity emerges from collective effects of singular components equipped with limited individual functionality. Top-down fabrication of plasmonic materials with a predesigned optical response in the visible range by conventional lithographic methods has remained challenging due to their limited resolution, the complexity of scaling, and the difficulty to extend these techniques to three-dimensional architectures. Molecular self-assembly provides an alternative route to create such materials which is not bound by the above limitations. We demonstrate how the DNA origami method can be used to produce plasmonic materials with a tailored optical response at visible wavelengths. Harnessing the assembly power of 3D DNA origami, we arranged metal nanoparticles with a spatial accuracy of 2 nm into nanoscale helices. The helical structures assemble in solution in a massively parallel fashion and with near quantitative yields. As a designed optical response, we generated giant circular dichroism and optical rotary dispersion in the visible range that originates from the collective plasmon-plasmon interactions within the nanohelices. We also show that the optical response can be tuned through the visible spectrum by changing the composition of the metal nanoparticles. The observed effects are independent of the direction of the incident light and can be switched by design between left- and right-handed orientation. Our work demonstrates the production of complex bulk materials from precisely designed nanoscopic assemblies and highlights the potential of DNA self-assembly for the fabrication of plasmonic nanostructures.Comment: 5 pages, 4 figure