Signed zeros of Gaussian vector fields-density, correlation functions and curvature

We calculate correlation functions of the (signed) density of zeros of Gaussian distributed vector fields. We are able to express correlation functions of arbitrary order through the curvature tensor of a certain abstract Riemann-Cartan or Riemannian manifold. As an application, we discuss one- and two-point functions. The zeros of a two-dimensional Gaussian vector field model the distribution of topological defects in the high-temperature phase of two-dimensional systems with orientational degrees of freedom, such as superfluid films, thin superconductors and liquid crystals.Comment: 14 pages, 1 figure, uses iopart.cls, improved presentation, to appear in J. Phys.

The distribution of extremal points of Gaussian scalar fields

We consider the signed density of the extremal points of (two-dimensional) scalar fields with a Gaussian distribution. We assign a positive unit charge to the maxima and minima of the function and a negative one to its saddles. At first, we compute the average density for a field in half-space with Dirichlet boundary conditions. Then we calculate the charge-charge correlation function (without boundary). We apply the general results to random waves and random surfaces. Furthermore, we find a generating functional for the two-point function. Its Legendre transform is the integral over the scalar curvature of a 4-dimensional Riemannian manifold.Comment: 22 pages, 8 figures, corrected published versio

Ground-dwelling arthropod responses to succession in a pinyon-juniper woodland

Stand-replacing wildfire is an infrequent but important disturbance in southwestern pinyon-juniper woodlands. A typical successional cycle in these woodlands is approximately 300 years or more after a stand-replacing fire. Arthropods, especially ground-dwelling taxa, are one of the most abundant and diverse fauna in terrestrial ecosystems and are typically responsive to microhabitat change. Little is known regarding community responses of ground-dwelling arthropods to changes in woodland successional stages from early ecosystems dominated by grasses, herbaceous plants, and fire adapted shrubs to tree-dominated old-growth ecosystems. In 2007 and 2008, within Mesa Verde National Park, Colorado, we compared the community composition of ground-dwelling arthropods between old-growth pinyon-juniper stands that were 300–400 years old and early successional areas recovering from a stand-replacing fire in 2002. The 2002 fire eliminated the dominant woody vegetation, which was replaced by increased herbaceous vegetation and bare ground. The early successional arthropod community showed a significantly higher abundance in major arthropod taxonomic groups, except spiders, compared to old-growth woodland. Old-growth species richness was greater in late August–September, 2007 and greater in early successional habitats during April–July, 2008. Spatial variability of the habitat was much greater in the recently burned early successional plots than the old-growth late successional plots. The differences in habitat were strongly correlated with arthropod community composition, suggesting that ground-dwelling arthropods are very sensitive to habitat changes. Habitat affiliation was strong, with 83% (early succession ruderal) and 91% (old-growth woodland) of the species found primarily or exclusively in one habitat. Many habitat indicator species (defined as species found in significantly greater abundance in one habitat) were found in both burned and old-growth habitats. Several species were found to be strict specialists exclusive to only one of these habitats. Collectively, the results suggest that heightened concern over loss of old-growth woodlands is warranted, given the distinct nature of the ground-dwelling arthropod community in old-growth habitats

Persistent holes in a fluid

We observe stable holes in a vertically oscillated 0.5 cm deep aqueous suspension of cornstarch for accelerations a above 10g. Holes appear only if a finite perturbation is applied to the layer. Holes are circular and approximately 0.5 cm wide, and can persist for more than 10^5 cycles. Above a = 17g the rim of the hole becomes unstable producing finger-like protrusions or hole division. At higher acceleration, the hole delocalizes, growing to cover the entire surface with erratic undulations. We find similar behavior in an aqueous suspension of glass microspheres.Comment: 4 pages, 6 figure

Case Report : Neuroblastoma-Like Schwannoma in a Domestic Short-Haired Cat

An axillary mass was detected in a 6-year-old, neutered, male, domestic short-haired cat during a wellness exam. Gross examination following surgical removal revealed a discrete, deep subcutaneous, discoid mass that was between 0.5- and 0.7-cm-in-diameter and diffusely firm and white. Histologically, the mass was well-demarcated, partially encapsulated, and expanded the panniculus carnosus. It was composed of tightly packed, giant rosettes of radially arranged fusiform cells stacked in one to 10 layers with peripherally palisading nuclei and with centrally oriented, fibrillary, cytoplasmic processes, and collagenous fibers. Laminin immunoreactivity and ultrastructural examination highlighted a continuous basal lamina outside the plasma membrane of each neoplastic cell. Neoplastic cells were immunoreactive for GFAP, S100, periaxin, and Sox-10 and were immunonegative for synaptophysin, smooth muscle actin, and pancytokeratin. Collective findings were consistent with a diagnosis of neuroblastoma-like schwannoma. This is the first veterinary report of this rare variant of benign schwannoma

Generalized "Quasi-classical" Ground State for an Interacting Two Level System

We treat a system (a molecule or a solid) in which electrons are coupled linearly to any number and type of harmonic oscillators and which is further subject to external forces of arbitrary symmetry. With the treatment restricted to the lowest pair of electronic states, approximate "vibronic" (vibration-electronic) ground state wave functions are constructed having the form of simple, closed expressions. The basis of the method is to regard electronic density operators as classical variables. It extends an earlier "guessed solution", devised for the dynamical Jahn-Teller effect in cubic symmetry, to situations having lower (e.g., dihedral) symmetry or without any symmetry at all. While the proposed solution is expected to be quite close to the exact one, its formal simplicity allows straightforward calculations of several interesting quantities, like energies and vibronic reduction (or Ham) factors. We calculate for dihedral symmetry two different $q$-factors ("$q_z$" and "$q_x$") and a $p$-factor. In simplified situations we obtain $p=q_z +q_x -1$. The formalism enables quantitative estimates to be made for the dynamical narrowing of hyperfine lines in the observed ESR spectrum of the dihedral cyclobutane radical cation.Comment: 28 pages, 4 figure

Implementation and Sustainment of a Statewide Telemedicine Diabetic Retinopathy Screening Network for Federally Designated Safety-Net Clinics

CONTEXT: Diabetic retinopathy (DR) is the leading cause of incident blindness among working-age adults in the United States. Federally designated safety-net clinics (FDSC) often serve as point-of-contact for patients least likely to receive recommended DR screenings, creating opportunity for targeted interventions to increase screening access and compliance. STUDY DESIGN AND METHODS: With such a goal, we implemented and assessed the longitudinal performance of an FDSC-based telemedicine DR screening (TDRS) network of 22 clinical sites providing nonmydriatic fundus photography with remote interpretation and reporting. Retrospective analysis of patient encounters between February 2014 and January 2019 was performed to assess rates of pathology and referral. A generalized estimating equation logistic regression model was used for subset analysis from audits of pre- and post-implementation screening rates. Finally, patient surveys were conducted and assessed as a measure of intervention acceptability. RESULTS: Of the 13,923 individual telescreening encounters (4327 female, 4220 male, and 5376 unspecified; mean [SD] age, 54.9 [12.5] years) studied, 10,540 were of adequate quality to identify 3532 (33.5%) patients with ocular pathology: 2319 (22.0%) patients had some level of DR with 1604 (15.2%) requiring specialist referral, and 808 (7.7%) patients required referral for other ocular pathologies. The mean screening rate for audited clinics in the year prior to program implementation was 29.9% (641/2147), which increased to 47.7% (1012/2124) in the program’s first year, doubling patients’ odds of being screened (OR 2.2; 95% CI: 1.3–3.7; P = .003). These gains were sustained over four years following implementation (OR 1.9; 95% CI: 1.1–3.1; P = .018) despite varied clinic screening performance (4-year averaged range, 22.9–55.1%). Odds of early detection likewise doubled for patients with consecutive screenings (OR 2.2, 95% CI: 2.0–2.4; P \u3c .001). Finally, surveyed patients preferred TDRS to specialist exams (82.5%; 776/941) and would recommend the service to friends (92.7%; 868/936). CONCLUSION AND RELEVANCE: A statewide, FDSC-centered TDRS network was successfully established and sustained in a medically underserved region of the United States. Our results suggest that large TDRS networks in FDSCs can increase screening access and compliance for otherwise unscreened populations, but outcomes can vary greatly among clinics. Further work to optimize program implementation is needed to maximize this model\u27s impact

A Gene Expression Panel is Accurate for Diagnosis and Monitoring Treatment of Eosinophilic Esophagitis in Adults

Eosinophilic esophagitis (EoE) can be difficult to diagnose. We aimed to evaluate whether a gene expression score could differentiate adult EoE cases from non-EoE controls and to determine whether scores normalized after treatment for EoE

Corn Stover Availability and Collection Efficiency Using Typical Hay Equipment

Corn stover has been identified as a potential feedstock for the production of fermentable sugars and thermochemical processes. The availability and efficiency of typical hay equipment for collecting corn stover has not been well quantified. Corn stover was collected for two years on a central Kentucky farm near Louisville. Six different harvesting treatments, using traditional hay equipment, were used to harvest corn stover. A rotary mower, rotary scythe (flail-type mower with windrow-forming shields), parallel bar rake, and a round baler were utilized. The average stover moisture content prior to grain harvest was above 40%, and field drying was required before baling. All treatments were analyzed for collection efficiency and corn stover yield. The stover collection yields varied from 1.93 to 5.34 dry t/ha, with collection efficiencies (ratio of stover collected to the total above-ground stover excluding grain) between 32.1% and 94.5%. The most promising collection strategy was disengaging the straw chopper and spreader to produce a windrow behind the combine. This windrow could then be baled in a separate operation that resulted in a collection efficiency of 74.1%