A generalization of Gabriel's Galois covering functors II: 2-categorical Cohen-Montgomery duality

Given a group $G$, we define suitable 2-categorical structures on the class of all small categories with $G$-actions and on the class of all small $G$-graded categories, and prove that 2-categorical extensions of the orbit category construction and of the smash product construction turn out to be 2-equivalences (2-quasi-inverses to each other), which extends the Cohen-Montgomery duality.Comment: 31 pages. I moved the Sec of G-GrCat into Sec 3, and added Lem 5.6. I added more explanations in the proof of Cor 7.6 with (7.5). I added Def 7.7 and Lem 7.8 with the necessary additional assumptions in Props 7.9 and 7.11. I added Lem 8.8 with a short proof, Rmk 8.9 and the proof of Lem 8.10. The final publication is available at Springer via http://dx.doi.org/10.1007/s10485-015-9416-

Animal-Plant Interactions in an Atriplex canescens Dominant Community Browsed by Cattle

Atriplex canescens is a relatively widespread shrub in rangelands of the western United States,with a longstanding reputation as a valuable browse resource for ruminants. The breeding system of tetraploid populations has been extensively studied both in common gardens and in natural populations. However, browser-driven alterations of shrub sex ratios, and the probable mechanisms involved in such processes, have received relatively little attention in these populations. We report results from a preliminary study conducted in a stand of A. canescens at a site on the shortgrass steppe. Numbers of young shrubs decreased with increasing shrub density. Sex ratios did not differ from the expected 55:35:10 pistillate : staminate : monecious ratio in grazed plots, but did differ significantly from this ratio in exclosures, where they were clearly more female-biased. We discuss probable grazing-related mechanisms that could account for these results

The Intrinsic Fundamental Group of a Linear Category

We provide an intrinsic definition of the fundamental group of a linear category over a ring as the automorphism group of the fibre functor on Galois coverings. If the universal covering exists, we prove that this group is isomorphic to the Galois group of the universal covering. The grading deduced from a Galois covering enables us to describe the canonical monomorphism from its automorphism group to the first Hochschild-Mitchell cohomology vector space.Comment: Final version, to appear in Algebras and Representation Theor

Rotura de cápsula posterior en cirugía de catarata: frecuencia, manejo y resultado visual

Para determinar la frecuencia de rotura de cápsula posterior (RCP) durante la cirugía decatarata, el manejo intra y postoperatorio y la agudeza visual (AV) final, se realizó unestudio observacional, retrospectivo, con fichas de pacientes sometidos a cirugía decatarata en nuestro servicio entre Abril de 2007 y Marzo de 2008. Se analizaron datosdemográficos, antecedentes patológicos, AV pre y postoperatoria, alteraciones a nivel delfondo de ojo, técnica quirúrgica, experiencia del cirujano, pérdida de vítreo durante lacirugía, tipo de vitrectomía, implante de lente intraocular, complicaciones postoperatorias.Setecientos cincuenta y cuatro pacientes fueron sometidos a cirugía de catarata en elperiodo de estudio, 54 (7.1%) presentaron RCP. Se seleccionaron fichas de 49 pacientescon RCP para el análisis de las variables. La edad promedio fue de 69 años, 38 pacientes(76%) tenían AV preoperatoria de cuenta dedos a buena percepción luminosa, 10pacientes (20.4%) presentaban dilatación pupilar menor a 6mm y 19 (38.8%)pseudoexfoliación capsular, 73.5% fueron operados por residentes. Se realizó extracciónextracapsular en el 79.6% de los casos. El 73.5% presentó pérdida de vítreo y se realizóvitrectomía, 69.4% recibió implante de lente intraocular y 26.5% presentó complicacionespostoperatorias. El 75.5% de los pacientes llegó a una AV postoperatoria mejor a 20/140.Se encontró relación estadísticamente significativa al comparar la AV postoperatoria conla presencia de complicaciones (p: 0.01). La RCP es una complicación a la que estánexpuestos todos los cirujanos de catarata y el manejo adecuado es fundamental paraevitar en lo posible las complicaciones y lograr una buena AV

Nosema bombi (Microsporidia: Nosematidae) and trypanosomatid prevalence in spring bumble bee queens (Hymenoptera: Apidae: Bombus) in Kansas

Citation: Tribodi, A., Cibils-Stewart, X., McCornack, B., & Szlanski, A. (2014). Nosema bombi (Microsporidia: Nosematidae) and Trypanosomatid Prevalence in Spring Bumble Bee Queens (Hymenoptera: Apidae: Bombus) in Kansas. Journal of the Entomological Society, 87(2), 225-233. https://doi.org/10.2317/JKES130730.1Several species of bumble bees are declining in the United States; these declining populations often show higher prevalence of Nosema bombi, a microsporidian pathogen. To date, surveys of bumble bee pathogens in the United States have only been conducted on workers and males, yet the health of a population is ultimately dependent on the success of colony-founding queens. We conducted a molecular-diagnostic survey of the prevalence of N. bombi and trypanosomatids, such as Crithidia bombi, in six species of spring queens (n  =  142) collected in 2011 and 2013 at three sites in central Kansas. Nosema bombi was found in 27% of Bombus pensylvanicus and 13% of B. auricomus but was not found in the other species sampled. Trypanosomatids were only found in B. pensylvanicus (9%) during the May 2013 sampling period. The high prevalence of N. bombi in B. pensylvanicus is consistent with other surveys for this pathogen in other castes, but the high prevalence of N. bombi in B. auricomus is a novel finding. Although the conservation status of B. auricomus has not been thoroughly assessed, two recently published surveys showed that B. auricomus were less common in portions of the species' range. Based on those findings and an oft-cited link between N. bombi prevalence and bumble bee species' decline (e.g., B. pensylvanicus) in other studies, our findings suggest B. auricomus populations in Kansas may warrant further scrutiny

Flow equations for Hamiltonians: Contrasting different approaches by using a numerically solvable model

To contrast different generators for flow equations for Hamiltonians and to discuss the dependence of physical quantities on unitarily equivalent, but effectively different initial Hamiltonians, a numerically solvable model is considered which is structurally similar to impurity models. By this we discuss the question of optimization for the first time. A general truncation scheme is established that produces good results for the Hamiltonian flow as well as for the operator flow. Nevertheless, it is also pointed out that a systematic and feasible scheme for the operator flow on the operator level is missing. For this, an explicit analysis of the operator flow is given for the first time. We observe that truncation of the series of the observable flow after the linear or bilinear terms does not yield satisfactory results for the entire parameter regime as - especially close to resonances - even high orders of the exact series expansion carry considerable weight.Comment: 25 pages, 10 figure

Categorification of a linear algebra identity and factorization of Serre functors

We provide a categorical interpretation of a well-known identity from linear algebra as an isomorphism of certain functors between triangulated categories arising from finite dimensional algebras. As a consequence, we deduce that the Serre functor of a finite dimensional triangular algebra A has always a lift, up to shift, to a product of suitably defined reflection functors in the category of perfect complexes over the trivial extension algebra of A.Comment: 18 pages; Minor changes, references added, new Section 2.

Anestesia sub-Tenoniana versus Anestesia Peribulbar en Cirugía Extracapsular de Catarata

Con el objeto de comparar la efectividad de la anestesia sub-tenoniana con la peribulbar en cirugía extracapsular de catarata, se seleccionaron aleatoriamente en la Fundación Visión de Asunción (Paraguay), 35 pacientes adultos para recibir anestesia sub-tenoniana (8 mujeres y 9varones) o anestesia peribulbar (13 mujeres y 5 varones). La presión intraocular (PIO) antes, al primer y a los diez minutos de la anestesia fue medida, como así también la motilidad de los músculos rectos a los 10 minutos de la anestesia, el grado de dolor del paciente durante y altérmino de la cirugía y el grado de satisfacción del cirujano. La elevación de la PIO con la peribulbar fue estadísticamente significativa (p<0,008) al minuto de la inyección, retornando a los diez minutos a los niveles basales en ambos grupos. Diez minutos después de la aplicación delanestésico se encontraron diferencias estadísticamente significativas entre los grupos en la elevación (p=0,005), abducción (p=0,02) y depresión (p=0,01) de los músculos rectos; como así también en los niveles de dolor intraquirúrgico (p=0,04), pero no en los niveles de dolor debido a laaplicación de la anestesia o en el grado de satisfacción del cirujano. En conclusión, la anestesia subtenoniana produjo menor elevación de la PIO que la peribulbar y la aquinesia parcial obtenida con ella no fue un factor limitante para el cirujano. Aunque mayor porcentaje del grupo de la anestesia sub-tenoniana refirió algún grado de dolor intraquirúrgico, fue considerado tolerable debido a que no fue necesario refuerzo del anestésico

Clostridium Perfringens: agente etiologico de queratitis infecciosa

Clostridium perfringens es un raro agente causal de queratitis infecciosa, usualmente produce enfermedades necrotizantes severas. Presentación del caso: Agricultor de 32 años, procedente de General Artigas, Paraguay consultó en un servicio debido a un trauma con metal, cable en ojo derecho. Fue tratado con cicloplégico, AINES (antiinflamatorio no esteroideo) y aplicación de lente de contacto terapéutico. Después de 18 días sin mejoría acudió al Departamento de Oftalmología del Hospital de Clínicas de la Universidad Nacional de Asunción. El paciente presentó ausencia de percepción luminosa en el ojo afecto, quemosis, hipopion y ulcera central de cornea (5 mm). Se tomó muestra por raspado de cornea y el examen directo reveló bacilos Gram positivos. Se realizó cultivo en placas de agar sangre, agar chocolate y en caldo tioglicolato incubados a 37ºC y en agar Sabouraud incubados a 28 ºC. Después del informe laboratorial se inició tratamiento con cefazolina 50 mg/ml y gentamicina 14 mg/ml cada hora. Del medio de enriquecimiento fue aislado Clostridium perfringens después de tres días. Desafortunadamente el paciente no asistió a su control

Small denominators, frequency operators, and Lie transforms for nearly integrable quantum spin systems

Based on the previously proposed notions of action operators and of quantum integrability, frequency operators are introduced in a fully quantum-mechanical setting. They are conceptually useful because another formulation can be given to unitary perturbation theory. When worked out for quantum spin systems, this variant is found to be formally equivalent to canonical perturbation theory applied to nearly integrable systems consisting of classical spins. In particular, it becomes possible to locate the quantum-mechanical operator-valued equivalent of the frequency denominators that may cause divergence of the classical perturbation series. The results that are established here link the concept of quantum-mechanical integrability to a technical question, namely, the behavior of specific perturbation series