Physical Electronics

Contains reports on three research projects

Carotid endarterectomy using regional anesthesia: technique and considerations

BackgroundCarotid endarterectomy (CEA) is one of the most effective operations in minimizing stroke risk in both symptomatic and asymptomatic patients with carotid stenosis in the United States. Awake CEA with regional anesthesia may decrease both perioperative complications and length of hospital stay. Techniques of performing awake CEA is not often described in published literature.ObjectiveTo describe our experience with CEA using regional anesthesia with a focus on patient selection, anatomic variations, and surgical technique including cervical regional block. We particularly focus on nuances of the awake approach.MethodsCEA using regional anesthesia is described in detail.ResultsSuccessful use of regional anesthesia during CEA without complication.ConclusionRegional anesthesia for CEA is an advantageous approach for cervical plaque removal in appropriate patients. Thoughtful patient selection, as well as understanding of anatomy and its variants, is required. Potential advantages and disadvantages are discussed

Model of Inhomogeneous Impurity Distribution in Fermi Superfluids

The standard treatment of impurities in metals assumes a homogeneous distribution of impurities. In this paper we study distributions that are inhomogeneous. We discuss in detail the "isotropic inhomogeneous scattering model" which takes into account the spatially varying scattering on the scale of the superfluid coherence length. On a large scale the model reduces to a homogeneous medium with renormalized parameter values. We apply the model to superfluid 3He, where porous aerogel acts as the impurity. We calculate the transition temperature Tc, the order parameter, and the superfluid density. Both A- and B-like phases are considered. Two different types of behavior are identified for the temperature dependence of the order parameter. We compare the calculations with experiments on 3He in aerogel. We find that most of the differences between experiments and the homogeneous theory can be explained by the inhomogeneous model. All our calculations are based on the quasiclassical theory of Fermi liquids. The parameters of this theory for superfluid 3He in aerogel are discussed.Comment: 14 pages, 9 figures, minor change

Mitigating Bighorn Sheep–Vehicle Collisions and Habitat Fragmentation with Overpasses and Adaptive Mitigation

As transportation infrastructure expands to accommodate increasing human population growth, wildlife–vehicle conflicts (WVCs) are a growing concern for motorist safety and wildlife populations. In the case of large ungulates, minimal information exists on successful mitigation of WVCs involving bighorn sheep (Ovis canadensis) and habitat fragmentation. Too address this void, we evaluated the effectiveness of 3 new wildlife overpasses, 3 culverts, 2 bridges, and ungulate exclusionary fencing as potential desert bighorn sheep (O. c. nelsoni; sheep) crossing opportunities along US Highway 93 in Arizona, USA. We evaluated sheep movements using global positioning system (GPS) radio-transmitter collars and remote cameras for 4 years from March 2011 to March 2015 and sheep–vehicle collision data collected from 2011 to 2020. Although GPS determined pre- and post-mitigation passage rates of sheep that crossed US Highway 93 were initially similar, they increased every year and were on average 217% higher following inclusion of wildlife crossings and by year 4 had ultimately increased 633% from pre-construction rates. Cameras recorded 6,936 crossings by a dozen wildlife species with sheep accounting for 95% of all crossings. Sheep used the 3 overpasses (90% of all sheep crossings) disproportionately more than the 3 culverts and 2 underpasses (10% of all sheep crossings) in the same area, and use of the 3 overpasses increased 905% in the first year. Sheep initially used the 30-m-wide overpasses at 83% and 175% higher passage rates than 2 15-m-wide structures; however, by year 4 passage rates were similar across overpasses. From February 2011 through February 2020, we documented 0.8 sheep–vehicle collisions/year for an overall 93.3% reduction from the 12 collisions per year previously documented. Most of the collisions occurred immediately following completion of the project and gradually reduced as sheep access points were identified and addressed through an adaptive mitigation process to iteratively improve success. Overpasses appear to be the preferred wildlife crossing type for sheep and when properly located and linked with ungulate exclusion fencing successfully reduced collisions and habitat fragmentation. These findings add to our knowledge base of effective roadway mitigation for different species. Long-term monitoring informs species learning curves, preference of wildlife crossing structure type, and adaptive mitigation opportunities to increase effectiveness of mitigation measures on current and future projects

TCR hypervariable regions expressed by T cells that respond to effective tumor vaccines

A major goal of immunotherapy for cancer is the activation of T cell responses against tumor-associated antigens (TAAs). One important strategy for improving antitumor immunity is vaccination with peptide variants of TAAs. Understanding the mechanisms underlying the expansion of T cells that respond to the native tumor antigen is an important step in developing effective peptide-variant vaccines. Using an immunogenic mouse colon cancer model, we compare the binding properties and the TCR genes expressed by T cells elicited by peptide variants that elicit variable antitumor immunity directly ex vivo. The steady-state affinity of the natural tumor antigen for the T cells responding to effective peptide vaccines was higher relative to ineffective peptides, consistent with their improved function. Ex vivo analysis showed that T cells responding to the effective peptides expressed a CDR3β motif, which was also shared by T cells responding to the natural antigen and not those responding to the less effective peptide vaccines. Importantly, these data demonstrate that peptide vaccines can expand T cells that naturally respond to tumor antigens, resulting in more effective antitumor immunity. Future immunotherapies may require similar stringent analysis of the responding T cells to select optimal peptides as vaccine candidates. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00262-012-1217-5) contains supplementary material, which is available to authorized users

Physical Electronics

Contains reports on three research projects

Physical Electronics

Contains reports on four research projects

Early MESSENGER Results for Less Abundant or Weakly Emitting Species in Mercury's Exosphere

Now that the Messenger spacecraft is in orbit about Mercury, the extended observing time enables searches for exospheric species that are less abundant or weakly emitting compared with those for which emission has previously been detected. Many of these species cannot be observed from the ground because of terrestrial atmospheric absorption. We report here on the status of MESSENGER orbital-phase searches for additional species in Mercury's exosphere

MESSENGER Searches for Less Abundant or Weakly Emitting Species in Mercury's Exosphere

Mercury's exosphere is composed of material that originates at the planet's surface, whether that material is native or delivered by the solar wind and micrometeoroids. Many exospheric species have been detected by remote sensing, including H and He by Mariner 10, Na, K, and Ca by ground-based observations, and H, Na, Ca, Mg, and Ca+ by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Other exospheric species, including Fe, AI, Si, 0, S, Mn, CI, Ti, OH, and their ions, are expected to be present on the basis of MESSENGER surface measurements and models of Mercury's surface chemistry. Here we report on searches for these species made with the Ultraviolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS). No obvious signatures of the listed species have yet been observed in Mercury's exosphere by the UVVS as of this writing. It is possible that detections are elusive because the optimum regions of the exosphere have not been sampled. The Sun-avoidance constraints on MESSENGER place tight limits on instrument boresight directions, and some regions are probed infrequently. If there are strong spatial gradients in the distribution of weakly emitting species, a high-resolution sampling of specific regions may be required to detect them. Summing spectra over time will also aid in the ability to detect weaker emission. Observations to date nonetheless permit strong upper limits to be placed on the abundances of many undetected species, in some cases as functions of time and space. As those limits are lowered with time, the absence of detections can provide insight into surface composition and the potential source mechanisms of exospheric material

Physical Electronics

Contains reports on three research projects