Un método offline de validación de firmas, independiente del escritor e invariante a escalas y rotaciones

Descargue el texto completo en el repositorio institucional de la Universidade Federal do Rio Grande do Sul: http://hdl.handle.net/10183/247543El problema de validación de firmas consiste en verificar si una firma fue realizada por una persona comparándola con firmas verdaderas de ésta. En esta investigación, se propone un nuevo método offline (e independiente del escritor) de validación de firmas (llamado VerSig-R) basado en features obtenidas con el método "Moving Least Squares" y features transferidas desde una red neuronal convolucional. En los experimentos realizados, VerSig-R supera ampliamente a técnicas que forman parte del estado del arte en datasets de firmas de estilo occidental (dataset CEDAR), y obtiene resultados competitivos en datasets de firmas de estilo oriental (datasets Bangla/Hindi). Adicionalmente, un grupo amplio de experimentos demuestran que VerSig-R es el método más robusto cuando se aplican escalas y rotaciones a las firmas. Adicionalmente, se presenta una discusión sobre el bias detectado en uno de los datasets de firmas usado, así como el desempeño del método VerSig-R en datasets cruzados, un estudio con humanos que muestra que el método propuesto supera la precisión de los humanos al momento de validar la autenticidad de las firmas. Finalmente, se presenta una discusión sobre el impacto del número de ejemplos (por escritor) usados durante el entrenamiento en el desempeño y tiempo de ejecución de VerSig-R.Handwritten signatures are still one of the most used and accepted methods for user authentication. They are used in a wide range of human daily tasks, including applications from banking to legal processes. The signature verification problem consists of verifying whether a given handwritten signature was generated by a particular person, by comparing it (directly or indirectly) to genuine signatures from that person. In this research work, a new offline writer-independent signature verification method is introduced (named VerSig-R), based on a combination of handcrafted Moving Least-Squares features and features transferred from a convolutional neural network. In our experiments, VerSig-R outperforms state-of-the-art techniques on Western-style signatures (CEDAR dataset), while also obtaining competitive results on South Asian-style handwriting (Bangla and Hindi datasets). Furthermore, a wide range of experiments demonstrate that VerSig-R is the most robust in relation to differences in scale and rotation of the signature images. This work also presents a discussion on dataset bias and on cross-dataset performance of VerSig-R, as well as a small user study showing that the proposed technique outperforms the expected human accuracy on the signature-verification task. Finally, a discussion on the impact of the number of signature examples (per writer) used during training on performance and execution time is presented.Brasil. Universidade Federal do Rio Grande do Sul. Fundação de Apoio. Bolsa de Pesquisa Projeto 8351 - INF/Petrobras 5850.0109395.18.9Tesi

Beyond Clinical High-Risk State for Psychosis: The Network Structure of Multidimensional Psychosis Liability in Adolescents

OBJECTIVES: The main goal of the present study was to analyze the network structure of schizotypy dimensions in a representative sample of adolescents from the general population. Moreover, the network structure between schizotypy, mental health difficulties, subjective well-being, bipolar-like experiences, suicide ideation and behavior, psychotic-like experiences, positive and negative affect, prosocial behavior, and IQ was analyzed. METHOD: The study was conducted in a sample of 1,506 students selected by stratified random cluster sampling. The Oviedo Schizotypy Assessment Questionnaire, the Personal Wellbeing Index-School Children, the Paykel Suicide Scale, the Mood Disorder Questionnaire, the Strengths and Difficulties Questionnaire, the Prodromal Questionnaire-Brief, the Positive and Negative Affect Schedule for Children Shortened Version, and the Matrix Reasoning Test were used. RESULTS: The estimated schizotypy network was interconnected. The most central nodes in terms of standardized Expected Influence (EI) were 'unusual perceptual experiences' and 'paranoid ideation'. Predictability ranged from 8.7% ('physical anhedonia') to 52.7% ('unusual perceptual experiences'). The average predictability was 36.27%, implying that substantial variability remained unexplained. For the multidimensional psychosis liability network predictability values ranged from 9% (estimated IQ) to 74.90% ('psychotic-like experiences'). The average predictability was 43.46%. The results of the stability and accuracy analysis indicated that all networks were accurately estimated. CONCLUSIONS: The present paper points to the value of conceptualizing psychosis liability as a dynamic complex system of interacting cognitive, emotional, behavioral, and affective characteristics. In addition, provide new insights into the nature of the relationships between schizotypy, as index of psychosis liability, and the role played by risk and protective factors.Swiss National Science Foundation (100019_159440)Europa FEDER La Rioja 2014-2020 (SRS 6FRSABC026

Modified Measures as an Effective Theory for Causal Fermion Systems

We compare the structures of the theory of causal fermion systems (CFS), an approach to unify Quantum Theory with General Relativity, with those of modified measure theories (MMT), which are a set of modified gravity theories. Spacetimes with MMT can be obtained as the continuum limit of a CFS. This suggests that MMT could serve as effective descriptions of modifications to General Relativity implied by CFS. The goal is to lay the foundation for future research on exploring which MMTs are consistent with the causal action principle of CFS

Obesidad como factor de riesgo a complicaciones intra y postoperatorias en colecistectomía laparoscópica en pacientes de la tercera edad

Objetivo. Determinar si la obesidad es un factor de riesgo para las complicaciones intraoperatorias y postoperatorias en colecistectomía laparoscópica en pacientes de la tercera edad Material y método. Se realizó un estudio analítico, observacional, cohorte, retrospectivo. La población estuvo constituida de 194 pacientes mayores de 65 años que fueron operados por colecistectomía laparoscópica en el Hospital Víctor Lazarte Echegaray durante el periodo 2014-2018. Estos fueron divididos en dos grupos, el primero consistió en 97 pacientes obesos y el segundo grupo de 97 pacientes no obesos. Una vez formados dichos grupos, se determinó la presencia o no de complicaciones intra y post operatorias en cada uno de los grupos. Resultados. Existió una relación estadísticamente significativa entre la obesidad y las complicaciones intraoperatorias y postoperatorias en colecistectomía laparoscópica en pacientes de la tercera edad, mediante la prueba chi-cuadrado (x2=5,575) hallándose un valor de p=0.018 (p<0.005) y un Riesgo Relativo (RR) de 3 para un IC al 95% (1,135 -7,931). Además se encontró que la incidencia de complicaciones intra y postoperatorias en pacientes con obesidad de la tercera edad sometidos a colecistectomía laparoscópica fue del 15.5% mientras que que la incidencia de complicaciones intra y postoperatorias en pacientes sin obesidad de la tercera edad sometidos a colecistectomía laparoscópica fue del 5.2%. Conclusión. La obesidad es un factor de riesgo para las complicaciones intraoperatorias y postoperatorias en colecistectomía laparoscópica en pacientes de la tercera edad.Objective. To determine if obesity is a risk factor for intraoperative and postoperative complications in laparoscopic cholecystectomy in elderly patients Material and method. An analytical, observational, cohort, retrospective study was carried out. The population consisted of 194 patients older than 65 years who underwent laparoscopic cholecystectomy at the Víctor Lazarte Echegaray Hospital during the period 2014-2018. These were divided into two groups, the first consisting of 97 obese patients and the second group of 97 non-obese patients. Once these groups were formed, the presence or absence of intra- and postoperative complications in each of the groups wa determined. Results There was a statistically significant relationship between obesity and intraoperative and postoperative complications in laparoscopic cholecystectomy in elderly patients, using the chi-square test (x2 = 5.575) finding a value of p = 0.018 (p <0.005) and a risk Relative (RR) of 3 for a 95% CI (1,135 -7,931). It was also found that the incidence of intra and postoperative complications in patients with obesity in the elderly undergoing laparoscopic cholecystectomy was 15.5% while the incidence of intra and postoperative complications in patients without obesity in the elderly undergoing laparoscopic cholecystectomy was 5.2% Conclusion. Obesity is a risk factor for intraoperative and postoperative complications in laparoscopic cholecystectomy in elderly patients.Tesi

Valuation of a new entrant in an oligopolistic market, including its option to abandon: A real-life case

The purpose of this paper is to increase current empirical evidence on the relevance of real options for explaining firm investment decisions in oligopolistic markets. We study an actual investment case in the Spanish mobile telephony industry, the entrant in the market of a new operator, Yoigo. We analyze the option to abandon in order to show the relevance of the possibility of selling the company in an oligopolistic market where competitors are not allowed free entrance. The NPV (net present value) of the new entrant is calculated as a starting point. Then, based on the general approach proposed by Copeland and Antikarov (2001), a binomial tree is used to model managerial flexibility in discrete time periods, and value the option to abandon. The strike price of the option is calculated based on incremental EBITDA margins due to selling customers or merging with a competitor

O impacto da pandemia COVID-19 para os trabalhadores terceirizados do Instituto Federal da Paraíba - Campus João Pessoa

O aumento da terceirização de mão de obra no serviço público é fato sob o prisma da otimização de serviços, redução de custos e busca por eficiência, agravado com a Lei da terceirização 13.429/17 e a reforma trabalhista Lei nº 13.467/17, inclusive o IFPB segue a tendência. Este trabalho de conclusão de curso traz um estudo sobre a terceirização de mão de obra no Instituto Federal da Paraíba, campus João Pessoa. O objetivo é analisar o impacto da pandemia COVID-19 para os trabalhadores terceirizados contratados para atuar na educação pública. Os trabalhadores terceirizados, quando comparados aos efetivos, apresentam regime de trabalho e condições diferentes, com redução de benefícios e/ou direitos, sendo este o caso dos trabalhadores terceirizados das empresas prestadoras de serviço no campus estudado, podendo ter impactos maiores para o trabalhador ou fragilidades, que o estudo propôs observar, para a gestão pública, na qualidade e execução de seu trabalho, principalmente diante do cenário pandêmico. A metodologia escolhida inclui uma pesquisa de campo (exploratória) de natureza qualitativa e quantitativa desenvolvida através da observação de campo, de conversas informais e a aplicação de 20 questionários com os prestadores de serviço e encarregados das contratadas e servidores públicos ligados à coordenação de contratos. Dentre os principais resultados destacam-se os problemas que afetam os trabalhadores terceirizados da instituição como, por exemplo, a precarização dos salários e o não cumprimento dos direitos trabalhistas. Como conclusão, observa-se a necessidade de ampliação do debate sobre a terceirização no serviço público como alternativas de gestão que favoreçam a qualidade de trabalho e que reduzam impactos externos, como o da covid-19 que mudou a dinâmica de vida e trabalho de toda uma sociedade

Analysis of the operating efficiency of mobile operators during the 2002 to 2008 period

This article aims to quantify the efficiency of mobile operators in Spain and other European countries such as France and Germany. The period considered is from 2002 to 2008. Linear regression is used to analyze the relationship between growth in revenue and gross operating margin (EBITDA) generated by the relevant operators and the aggregate industry in each country. At the industry level, it is shown that (i) there is a strong correlation between revenue and margin; and (ii) this correlation weakens when competitive intensity grows. At the operator level, those which achieved larger increases in revenues did not sacrifice their margins, but offset the additional investments and costs required to achieve said growth through economies of scale

A quadratic cumulative production model for the material balance of an abnormally pressured gas reservoir

The premise of this research is the concept, development, and application of an approximate relation for the material balance of abnormally-pressured gas reservoirs. The approximation is formulated directly from the rigorous material balance for the case of an abnormally-pressured gas reservoir. The primary assumption in this derivation is that WGp <1 or Ce(p)(pi-p)<1. Further, we can proceed by assuming that W is either constant or some arbitrary function. If we assume W=constant, then the following form results: At first glance there may be concern that this approximation is not sufficiently valid for field applications however, we have shown this relation to be an extraordinarily accurate approximation of the rigorous material balance. This result is suited not only for use as a characteristic model, but also for use as a data analysis mechanism (i.e., this result is used to develop a suite of analysis plots, plotting functions, a type curve, etc.). In this work we provide the following new results: 1) A suite of 6 (six) plotting functions based on the p/z-Gp2 material balance model. 2) A suite of 4 (four) p/z-Gp performance plots which are used to calibrate analysis. 3) A new type curve in terms of a dimensionless pressure function (pD=(pi/zi-p/z)/pi/zi) versus a dimensionless cumulative production function (GpD=Gp/G), where the type curve solution is based on the new p/z-Gp^2 (a quadratic material balance) model

Determination of patulin in apple and derived products by UHPLC-MS/MS. Study of matrix effects with atmospheric pressure ionisation sources.

Sensitive and reliable analytical methodology has been developed for the measurement of patulin in regulated foodstuffs by using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC–MS/MS) with triple quadrupole analyser. Solid samples were extracted with ethyl acetate, while liquid samples were directly injected into the chromatographic system after dilution and filtration without any clean-up step. Chromatographic separation was achieved in less than 4 min. Electrospray (ESI) and atmospheric pressure chemical ionisation (APCI) sources were evaluated, in order to assess matrix effects. The use of ESI source caused strong signal suppression in samples; however, matrix effect was negligible using APCI, allowing quantification with calibration standards prepared in solvent. The method was validated in four different apple matrices (juice, fruit, puree and compote) at two concentrations at the low μg kg−1 level. Average recoveries (n = 5) ranged from 71% to 108%, with RSDs lower than 14

Inhibition of larval growth and adult fecundity in Asian long-horned beetle (Anoplophora glabripennis) exposed to azadirachtins under quarantine laboratory conditions

BACKGROUND: The Asian long-horned beetle [ALB; Anoplophora glabripennis (Motschulsky)] is an invasive, wood-boringinsect posing significant economic and ecological threats to the deciduous forests of North America. An efficacious andenvironmentally acceptable chemical control technique is a requirement of a comprehensive, integrated response strategy.RESULTS: Results of this study demonstrate statistically significant, concentration-dependent effects of azadirachtins, a familyof natural compounds derived f rom the neem tree, on both ALB larval and adult life stages. Growth inhibitory effects on ALBlarvae were greatest on early life stages. Significant effects on adults included inhibition of female feeding, oviposition effortand fecundity for adults exposed to azadirachtins via maturation feeding on systemically loaded twigs.CONCLUSION: These quarantine laboratory experiments verify multi-mechanistic, deleterious effects on both larval and adultlife stages of ALB, an exotic, invasive insect pest of critical importance in North America. Field efficacy studies are requiredto further understand dose acquisition by larval and adult ALB life stages following systemic injections to host trees undersemi-operational use scenarios. Such studies could also be used to test postulates regarding optimal deployment strategiesto meet objectives such as slowing the spread of this pest and protection of high-value deciduous forest resources