Indefinite theta functions and black hole partition functions

We explore various aspects of supersymmetric black hole partition functions in four-dimensional toroidally compactified heterotic string theory. These functions suffer from divergences owing to the hyperbolic nature of the charge lattice in this theory, which prevents them from having well-defined modular transformation properties. In order to rectify this, we regularize these functions by converting the divergent series into indefinite theta functions, thereby obtaining fully regulated single-centered black hole partitions functions.Comment: 35 pages; v2: various comments added; v3: a few typos correcte

Electronic Transport Properties of Incipient Graphitic Domains Formation in PAN Derived Carbon Nanofibers

The carbon nanofibers used in this work were derived from a polyacrylonitrile (PAN)/N, N-dimethyl formamide (DMF) precursor solution using electrospinning and vacuum pyrolysis techniques. Their conductivity, σ, was measured at temperatures between 1.9 and 300 K and transverse magnetic field between -9 and 9 T. Zero magnetic field conductivity σ(0,T) was found to increase monotonically with the temperature with a convex σ(0,T) versus T curve. Conductivity increases with the external transverse magnetic field, revealing a negative magnetoresistance at temperatures between 1.9 and 10 K, with a maximum magnetoresistance of - 75 % at 1.9 K and 9 T. The magnetic field dependence of the conductivity and the temperature dependence of the zero-field conductivity are best described using the two-dimensional weak localization effect

Pyrolysis Temperature and Time Dependence of Electrical Conductivity Evolution for Electrostatically Generated Carbon Nanofibers

Carbon nanofibers were produced from polyacrylonitrile/N, N-Dimethyl Formamide (PAN/DMF) precursor solution using electrospinning and vacuum pyrolysis at temperatures from 773-1273 K for 0.5, 2, and 5 h, respectively. Their conductance was determined from I – V curves. The length and cross-section area of the nanofibers were evaluated using optical microscope and scanning probe microscopes, respectively, and were used for their electrical conductivity calculation. It was found that the conductivity increases sharply with the pyrolysis temperature, and increases considerably with pyrolysis time at the lower pyrolysis temperatures of 873, 973, and 1073 K, but varies, less obviously, with pyrolysis time at the higher pyrolysis temperatures of 1173 and 1273 K. This dependence was attributed to the thermally activated transformation of disordered to graphitic carbons

Street food: factors influencing perception of product quality

Purpose – The purpose of this study is to evaluate whether the perceptions of cleanliness and organization of the point of sale, hygiene and training of those who serve the public (service) and healthiness of the products, constitute a base for the perception of the quality of food sold in the street. Studies about development of street food trade have gained relevance in academic debate because of its social and economic significance. Usually, aspects related to sanitary issues are presented, and the factors that influence consumer perception regarding quality of food consumed are less explored. This was the focus of this work. The relationships among possible predecessors – attendance, cleanliness, organization and healthiness – were tested, all acting together, influencing the variable perception of product quality. Competitive models were tested because of theoretical divergences regarding the relationship between quality and healthiness, not yet totally clear in the literature. Design/methodology/approach – A quantitative survey was carried out in the city of Diadema (SP, Brazil), getting 603 respondents, with data and theoretical models analyzed by structural equation modeling. Findings – Results indicated that organization variable is not significant regarding perception of product quality, while attendance and healthiness directly affect this perception. On the other hand, cleanliness influences perceived healthiness and this, in turn, reinforces perception of product quality. Practical implications – The focus of street food traders should be on clerk cleanliness and politeness (characteristics related to the service) that end up influencing the perception that the consumer develops regarding healthiness (characteristic related to product quality). Originality/value – Usually research studies on this theme include only aspects related to sanitary and safety issues, and those which focus on consumer perception of food quality cover conventional outlets such as bars and restaurants. There are few ones performed as in this study that analyze street food consumer behavior regarding his/her perception of quality, cleanliness, care received, among others

Supra and intracondylar open fracture of the femur in a motocross athlete: case report

The authors report the case of a patient (amateur motocross competitor) who suffered a fall during a motocross competition resulting in a supra and intracondylar open fracture in the right femur.Os autores apresentam o relato de um caso de uma paciente (atleta amador de motocross) que sofreu uma queda durante uma competição e teve fratura supra e intracondiliana exposta de fêmur direito.Universidade Federal de São Paulo (UNIFESP) Departamento de Ortopedia e Traumatologia Centro de Traumatologia do EsporteHospital e Maternidade Assunção Departamento de Ortopedia e TraumatologiaUNIFESP, Depto. de Ortopedia e Traumatologia Centro de Traumatologia do EsporteSciEL

Common injuries in athletes' knee: experience of a specialized center

OBJECTIVE:The present cross-sectional study aims to identify the most common knee injuries in athletes cared at a Specialized Outpatient Clinics.METHOD:Analysis of patients cared at the Knee Outpatient Clinics of a Sports Trauma Center, divided by gender, age and diagnosed injury.RESULTS:Initially 440 patients were divided into 33 types of sports; after excluding the less statistically significant practices, nine sports remained. The most frequently performed sports were football with almost 50% of total patients presenting anterior cruciate ligament (ACL) injury, and road runs with great frequency of meniscal injury. There was no correlation of the disorder with the type of sports performed but a correlation was found with patient's age/gender.CONCLUSION:The complete ACL rupture was the most common injury found in football, basketball and volleyball players, followed by meniscal injury in street runners.Level of Evidence IV, Study Transversal.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Department of Orthopedics and TraumatologyUniversidade Federal de São Paulo (UNIFESP) Department of Orthopedics and TraumatologyUNIFESP, EPM, Department of Orthopedics and TraumatologyUNIFESP, Department of Orthopedics and TraumatologySciEL