Simulation of Clinical PET Studies for the Assessment of Quantification Methods

On this PhD thesis we developed a methodology for evaluating the robustness of SUV measurements based on MC simulations and the generation of novel databases of simulated studies based on digital anthropomorphic phantoms. This methodology has been applied to different problems related to quantification that were not previously addressed. Two methods for estimating the extravasated dose were proposed andvalidated in different scenarios using MC simulations. We studied the impact of noise and low counting in the accuracy and repeatability of three commonly used SUV metrics (SUVmax, SUVmean and SUV50). The same model was used to study the effect of physiological muscular uptake variations on the quantification of FDG-PET studies. Finally, our MC models were applied to simulate 18F-fluorocholine (FCH) studies. The aim was to study the effect of spill-in counts from neighbouring regions on the quantification of small regions close to high activity extended sources

Universal Cycles for Some Combinatorial Objects

A de Bruijn cycle commonly referred to as a universal cycle (u-cycle), is a complete and compact listing of a collection of combinatorial objects. In this paper, we show the power of de Bruijn\u27s original theorem, namely that the cycles bearing his name exist for n-letter words on a k-letter alphabet for all values of k,n, to prove that we can create de Bruijn cycles for multi-sets using natural encodings and M-Lipschitz n-letter words and the assignment of elements of [n]={1,2,...,n} to the sets in any labeled subposet of the Boolean lattice; de Bruijn\u27s theorem corresponds to the case when the subposet in question consists of a single ground element. In this paper, we also show that de Bruijn\u27s cycles exist for words with weight between s and t, where these parameters are suitably restricted

Differences of vegetation structure and diversity of a forest in an altitudinal gradient of the Sierra La Laguna Biosphere Reserve, Mexico

Abstract Background: The Sierra La Laguna Biosphere Reserve is located which is considered an “island of vegetation” within an arid environment. Considering that this protected natural area has an altitudinal gradient that ranges from 500 to 2,100 meters above sea level. Hypothesis: Higher altitudinal gradient decreases abundance, basal area and diversity of plant species. Studied species and data description: The data analyzed in this study included the structural variables of abundance (N ha-1), basal area (m2 ha-1) and diversity (alfa and beta) of arborous species in areas with different elevations. Study site and dates: This study was carried out in four localities of the tropical deciduous forest and broadleaved forest. In the spring of 2016. Methods: Five circular sampling plots of 500 m2 for arborous vegetation and 1m2 for herbaceous vegetation were established in every vegetation community, resulting in 20 sampling plots. Results: Sixteen families, 22 genera and 22 vascular plant species were recorded. The most diverse family was Fabacea with four species followed by Cactaceae with three species. The abundance, dominance and diversity of vegetation species did not show any decrease (or increase) tendency of values as the altitudinal gradient augmented. Conclusions: The hypothesis is rejected because abundance, dominance and diversity of vegetation species do not show any decrease or increase tendency as the altitudinal gradient augmented. The vegetation communities showed a high similarity in the composition of species. Key words: Altitudinal gradient, Baja California, diversity, species richness, vegetation structure. Resumen Antecedentes: La Reserva de la Biosfera Sierra la Laguna se encuentra en lo que es considerado una “isla de vegetación” dentro de un ambiente árido. Considerando que esta área natural protegida tiene un rango altitudinal que va desde los 500 a 2,100 metros sobre el nivel del mar. Hipótesis: A mayor gradiente altitudinal disminuye la abundancia, área basal y diversidad de las especies vegetales. Especies de estudio y descripción de datos: La información analizada en este estudio incluyó las variables estructurales de abundancia (N ha-1), el área basal (m2 ha-1) y diversidad (alfa y beta) de especies arbóreas en áreas con diferentes elevaciones. Sitio de estudio y año de estudio: Este estudio fue realizado en cuatro comunidades de selva baja caducifolia y bosque de latifoliadas. En la primavera de 2016. Métodos: Cinco parcelas circulares de 500 m2 para vegetación arbórea y 1m2 para vegetacion herbácea fueron establecidas en cada comunidad vegetal, resultado en 20 parcelas de muestreo. Resultados: Dieciséis familias, 22 géneros y 22 especies de plantas vasculares fueron registradas. La familia más diversa fue Fabacea con cuatro especies, seguido de Cactaceae con tres especies. La abundancia, dominancia y diversidad de especies vegetales no mostró una tendencia decreciente (o incremento) conforme el gradiente altitudinal aumentó. Conclusiones: La hipótesis fue rechazada debido a que la abundancia, dominancia y diversidad de especies vegetales no mostró ninguna tendencia decreciente (o incremento) en los valores conforme el gradiente altitudinal aumenta. Las comunidades vegetales mostraron una alta similitud en la composición de especies. Palabras clave: Baja California, diversidad, estructura vegetal, gradiente altitudinal, riqueza de especies

A Theoretical Study of the Hydrodynamic Performance of an Asymmetric Fixed-Detached OWC Device

The chamber configuration of an asymmetric, fixed-detached Oscillating Water Column (OWC) device was investigated theoretically to analyze its effects on hydrodynamic performance. Two-dimensional linear wave theory was used, and the solutions for the associated radiation and scattering boundary value problems (BVPs) were derived through the matched eigenfunction expansion method (EEM) and the boundary element method (BEM). The results for the hydrodynamic efficiency and other important hydrodynamic properties were computed and analyzed for various cases. Parameters, such as the length of the chamber and the thickness and submergence of the rear and front walls, were varied. The effects on device performance of adding a step under the OWC chamber and reflecting wall in the downstream region were also investigated. A good agreement between the analytical and numerical results was found. Thinner walls and low submergence of the chamber were seen to increase the efficiency bandwidth. The inclusion of a step slightly reduced the frequency at which resonance occurs, and when a downstream reflecting wall is included, the hydrodynamic efficiency is noticeably reduced at low frequencies due to the near trapped waves in the gap between the OWC device and the rigid vertical wall.The current investigation was developed under the framework of the Basque Government (IT1314-19 research group). The authors additionally thank the funding provided by CEMIE-Océano (Mexican Centre for Innovation in Ocean Energy). Project FSE-2014-06-249795 financed by CONACYT-SENER Sustentabilidad Energética

Características sociodemográficas de adolescentes embarazadas menores de 16 años de una unidad de medicina familiar en San Luis Potosí, México

ResumenObjetivoidentificar las características sociodemográficas de adolescentes embarazadas menores de 16 años de la unidad de medicina familiar no. 45 del Instituto Mexicano del Seguro Social (imss), Delegación San Luis Potosí, México.Material y métodosestudio descriptivo y transversal. Muestra: no probabilística por conveniencia. Se efectuó entre el 2 de enero y el 30 de noviembre de 2011. Se incluyeron 41 adolescentes embarazadas menores de 16 años, las cuales participaron de forma voluntaria; en todos los casos se solicitó la autorización correspondiente. El instrumento de recolección de datos incluyó: ficha de identificación, antecedentes sociofamiliares, antecedentes relacionados con el embarazo actual y antecedentes patológicos, con un total de 28 ítems.Resultadosse entrevistó a 41 adolescentes, 34 de entre 15 y 16 años y siete de entre 13 y 14 años. Un total de 33 adolescentes pertenecía a familias nucleares y ocho a familias monoparentales; 28 adolescentes estaban integradas a familias modernas y 13 a familias tradicionales; 38 pertenecían a hogares con estrato socioeconómico bajo y tres con estrato medio bajo.Conclusioneslos médicos de los tres niveles de atención deberían estar más comprometidos con la difusión de la educación sexual para los adolescentes y con ser fuente eficaz de información anticonceptiva. Se deberían replantear las estrategias que se llevan a cabo en la prevención tanto primaria como secundaria del embarazo en adolescentes.SummaryObjectiveto identify the social-demographic characteristics of pregnant adolescents under 16 years old of the Family Medicine Unit No. 45 of the Mexican Institute of Social Security (imss), in San Luis Potosi, Mexico.Material and methodsdescriptive and cross-sectional study: non-probabilistic by convenience. The study was carried out between January 02 and November 30, 2011. It was included 41 pregnant adolescents under 16, which participated on a voluntary basis; in all cases the authorization was requested. The data collection instrument included: identification card, social and family history and background related to the current pregnancy and pathological history, with a total of 28 items.Results41 adolescents were interviewed, 34 of them between 15 and 16 years and seven between 13 and 14 years old. A total of 33 teenagers belonged to nuclear families and eight to single-parent families; 28 adolescents were part of modern families and 13 to traditional families; 38 belonged to low socioeconomic level homes and three to medium low level.ConclusionsPhysicians of the three levels of care should be more committed to the diffusion of sexual education for adolescents and be a more effective source of contraceptive information. They should reconsider strategies that are carried out in both primary and secondary prevention of Teenage Pregnancy

Preliminary Experience with Small Animal SPECT Imaging on Clinical Gamma Cameras

The traditional lack of techniques suitable for in vivo imaging has induced a great interest in molecular imaging for preclinical research. Nevertheless, its use spreads slowly due to the difficulties in justifying the high cost of the current dedicated preclinical scanners. An alternative for lowering the costs is to repurpose old clinical gamma cameras to be used for preclinical imaging. In this paper we assess the performance of a portable device, that is, working coupled to a single-head clinical gamma camera, and we present our preliminary experience in several small animal applications. Our findings, based on phantom experiments and animal studies, provided an image quality, in terms of contrast-noise trade-off, comparable to dedicated preclinical pinhole-based scanners. We feel that our portable device offers an opportunity for recycling the widespread availability of clinical gamma cameras in nuclear medicine departments to be used in small animal SPECT imaging and we hope that it can contribute to spreading the use of preclinical imaging within institutions on tight budgets.This work was supported in part by public Fondo de Investigaciones Sanitarias ISCIII PS09/01206 and PI11/01806. P. Aguiar was awarded a public fellowship from Xunta de Galicia, POS-A/2013/001S

Geant4-GATE Simulation of a Large Plastic Scintillator for Muon Radiography

Envisaging the possibility of using large-area plastic scintillator slabs as robust detectors for high spatial resolution muon radiography, and prior to prototype development, we study expected basic performance by Monte Carlo simulation. We present preliminary results for a scalable square footprint detector unit of similar to 1 m(2), defining a representative simulation model volume of 50 cm x 50 cm, with reflective surfaces and a light readout by direct coupling of 4 small PMTs (in a square arrangement) at one face of the scintillator slab. Light detection efficiency is calculated for several light collection configurations, considering different values of surface roughness, reflectivity, optical coupling index and scintillator thickness. Values maximizing photon detection have been identified. The light response function of 2.5-3.5 cm diameter PMTs for the proposed configuration has been determined. A detector intrinsic spatial resolution of the order of 1 cm is estimated for muon interactions at the center region of the detector module, using a simple centroid positioning algorithm (Anger logic)

Preliminary experience with small animal SPECT imaging on clinical gamma cameras

The traditional lack of techniques suitable for in vivo imaging has induced a great interest in molecular imaging for preclinical research. Nevertheless, its use spreads slowly due to the difficulties in justifying the high cost of the current dedicated preclinical scanners. An alternative for lowering the costs is to repurpose old clinical gamma cameras to be used for preclinical imaging. In this paper we assess the performance of a portable device, that is, working coupled to a single-head clinical gamma camera, and we present our preliminary experience in several small animal applications. Our findings, based on phantom experiments and animal studies, provided an image quality, in terms of contrast-noise trade-off, comparable to dedicated preclinical pinhole-based scanners. We feel that our portable device offers an opportunity for recycling the widespread availability of clinical gamma cameras in nuclear medicine departments to be used in small animal SPECT imaging and we hope that it can contribute to spreading the use of preclinical imaging within institutions on tight budgets

Combination of DROOL rules and Protégé knowledge bases in the ONTO-H annotation tool

ONTO-H is a semi-automatic collaborative tool for the semantic annotation of documents, built as a Protégé 3.0 tab plug-in. Among its multiple functionalities aimed at easing the document annotation process, ONTO-H uses a rule-based system to create cascading annotations out from a single drag and drop operation from a part of a document into an already existing concept or instance of the domain ontology being used for annotation. It also gives support to the detection of name conflicts and instance duplications in the creation of the annotations. The rule system runs on top of the open source rule engine DROOLS and is connected to the domain ontology used for annotation by means of an ad-hoc programmed Java proxy

Satisfacción laboral y rotación del personal en empresas del rubro hotelero

RESUMEN Para realizar el análisis del sector hotelero, se recurrió a la búsqueda de información sistemática donde se recopilaron estudios de revistas científicas y tesis de las universidades más importantes del país y del mundo, en ellas se detallaban los puntos más importantes de la satisfacción laboral, la rotación de personal y todo lo que tiene relación directa con el tema. Según las fuentes consultadas, se determinó que la satisfacción laboral está vinculada a la calidad de servicio de igual manera, se hallaron evidencias que reafirman que los bajos niveles de motivación, la insatisfacción en el tema salarial, la ausencia de beneficios sociales y desarrollo personal y profesional son las principales causas para que los colaboradores decidan abandonar sus puestos de trabajo. También se menciona la relación que existe entre la satisfacción laboral y la satisfacción con la vida. Con esta investigación se pretende comunicar la importancia del capital humano en las empresas del sector hotelero, ya que finalmente son los colaboradores quienes tienen contacto directo con el cliente externo. Ofrecer un ambiente grato de trabajo, bienestar y equilibrio entre la vida laboral y profesional resulta ser la clave para lograr que el personal se sienta parte de la organización. PALABRAS CLAVES: Satisfacción laboral, motivación, calidad, servicio al cliente, rotación de personal