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Fiber-reinforced composite resin systems (FRC) are widely used materials in engineering and biomedicine. For approximately 40 years they have been investigated demonstrating their excellent mechanical properties. From a clinical perspective, they are suggested in different disciplines of dentistry, where their applications are evidenced-based. With the introduction of new technologies and bonding protocols, these types of materials can be used as substructures. The attempt to explore the properties and applications of FRC's materials in non-everyday clinical cases, allows us to provide a viable alternative in the planning of complex restorative treatments. Las fibras reforzadas con resina compuesta (FRC) son materiales ampliamente utilizados en el área de la ingeniería y la biomedicina. Durante aproximadamente 40 años, vienen siendo investigados demostrando sus excelentes propiedades mecánicas. Desde la perspectiva clínica, se sugieren en diferentes disciplinas de la odontología, donde sus aplicaciones se sustentan con base en los resultados de evidencia científica. Con la introducción de nuevas tecnologías e incorporación de protocolos de adhesión, los materiales fabricados con fibras embebidas en matrices de resina, se recomiendan como subestructuras de soporte. El intento de explorar las propiedades y aplicaciones de los materiales FRC’s, en casos clínicos no cotidianos, nos permite brindar una alternativa viable para el planeamiento de tratamientos restauradores.

Ceramic veneers are considered viable alternatives compared to classic invasive procedures applied in restorative treatments. Adhesive bonding techniques combined with restorative materials that mimic the natural color of the tooth are part of one of the greatest achievements in modern aesthetic dentistry. Ceramic veneers structurally made with lithium disilicate materials are frequently selected to restore and stabilize the biomechanics of the tooth in cases with dental malformations, such as conoid teeth. This article explains the basic principles applied to the design of ceramic veneers, with copings in lithium disilicate and covered with feldspathic ceramic. Moreover, the long-term prognosis of ceramic veneers based on scientific evidence. Las carillas de cerámica son consideradas, alternativas viables en comparación con los procedimientos clásicos invasivos, utilizados en los tratamientos dentales. Las técnicas de unión adhesiva, combinadas con materiales similares al color natural del diente, forman parte de, los grandes logros alcanzados dentro de la odontología estética moderna. Las carillas de cerámica fabricadas estructuralmente a partir de materiales vítreos reforzados con disilicato de litio, son seleccionadas con frecuencia para restaurar y estabilizar la biomecánica del diente, sugiriéndose específicamente desde, la indicación de piezas dentales con insuficiente tejido de esmalte, hasta, la presencia de malformaciones dentales como, dientes conoides. El presente artículo explicará, los principios básicos aplicados en la tecnología avanzada para diseñar carillas de cerámica con subestructuras de soporte “coppings”, en disilicato de litio, permitiendo observar, el proceso de cobertura con cerámica feldespática en el laboratorio y el resultado final del procedimiento clínico, en la cementación. Explorará el pronóstico a largo plazo de carillas de cerámica según la información fundamentada en una serie de estudios científicos con base en evidencia científica.

Restoration of fractured anterior teeth presents a challenge to dental clinicians owing to its esthetic requirements and, more importantly, because of the young age of the patients. Thus, it is important to follow the most conservative protocol. Many professionals face the dilemma of whether or not to perform enamel beveling. This article briefly discusses the clinical perspective and evidence regarding this type of operative restoration procedure. Resumen: La restauración de dientes anteriores fracturados representa un desafío para los odontólogos debido a sus requisitos estéticos y, lo que es más importante, debido a la corta edad de los pacientes que generalmente necesitan del tratamiento. Por lo tanto, es importante seguir el protocolo más conservador. Muchos profesionales enfrentan el dilema de si realizar o no el biselado del esmalte. Este artículo discute brevemente la perspectiva clínica y la evidencia con respecto a este tipo de procedimiento de restauración quirúrgica.

The preservation of healthy dental structures contributes to the practice of a conservative dentistry. This concept involves the implementation of biological and mechanical principles in a more predictable manner. Minimally invasive cavity preparations are the complement to the selection of adhesive and composite resin materials. The correct application of an adhesive protocol will provide imperceptible aesthetic restorations and adequate clinical performance. La preservación de tejido dental sano contribuye a la práctica de una Odontología conservadora, permitiendo la aplicación de los principios biológicos y mecánicos de una forma más predecible. Las preparaciones cavitarias mínimamente invasivas son el complemento de la correcta selección de materiales adhesivos y de resina compuesta. La correcta aplicación de un protocolo adhesivo nos proporcionará resultados estéticos imperceptibles y un longevo desempeño clínico.

Nowadays agriculture is facing constantly challenges to produce more and better food for a growing population under a changing climate scenery. To afford this demand, agricultural practices must innovate in new methods for crop production, nutrition management, and plant health. In addition, the development of new compounds or biological agents able to improve plant yield (regulating plant physiology, metabolism, crop performance), and agro-product quality, are also necessary. In the last decade, agents with these characteristics have been proposed for a sustainable agriculture. These agents, defined as biostimulants, have showed to improve plant nutrition, quality, yield and abiotic tolerance in different agricultural crops. In particular, the use of protein hydrolysates as biostimulants offers promising results to reduce the use of agrochemicals and improve productivity parameters in a variety of cultivars, in agree with the modern agricultural production challenges. The present review is focused in the use of protein hydrolysates as plant biostimulants, describing typical and potential agro industrial by-products as sources substrates for protein-based biostimulants formulation, and commercial or experimental proteolytic enzymes used for hydrolysate production. Moreover, critical aspects during protein biostimulants manufacture, functional profiling and its applications are discussed. Finally, recent advances for the evaluation of protein hydrolysates on plant physiology and metabolism under experimental and commercial scale are also documented. Concluding in the necessity to conduct structural studies, in order to identify and produce bioactive peptides with agricultural applications.

This study shows the role of justice as a success factor in hotel outsourcing relationships. More specifically, it investigates the associations between two different dimensions of justice (procedural and distributive) and attitudes and behaviors in the relationship with suppliers, in terms of trust, cooperation, and long-term orientation. The work also analyzes to what degree these behavioral elements influence suppliers’ proactive improvement, and whether cooperation mediates these relationships. The study provides a unique perspective on this dynamic and the results of the relationships between suppliers and hotels. The results establish that the perception of distributive justice has a positive influence on the long-term orientation of the outsourcing relationship, whereas the perception of procedural justice negatively influences the long-term orientation. The research findings provide evidence about the influence of procedural and distributive justice on trust in the outsourcing relationships, and that trust has a positive impact on cooperation and a long-term orientation. The results show that the long-term orientation and trust do not directly influence proactive improvement, but there is an indirect effect through cooperation.

Clinical research and in vitro laboratory tests have enabled the development and improvement of dental ceramics. Comprehension of the physical and mechanical properties of this material is essential, in order to ensure a functional, aesthetic and long-lasting posterior ceramic restoration. The clinical protocol for onlay preparation involves important considerations in treatment planning, such as selection of the restorative material, biomechanical design, color selection, dental substrates conditioning and adhesive cementation. This article discusses a brief review on the topic and a case presentation in which a posterior tooth was rehabilitated with an IPS Empress Esthetic® ceramic onlay.

This study empirically identifies the role of the outsourcing strategy in the hotel sector. The study determines what strategic benefits and risks determine that an outsourcing strategy is accepted by hotel managers. This paper analyzes perceptions and evaluations of policies related to outsourcing. To do so, it analyzes to what degree the manager's attitude about outsourcing is influenced by tactical and strategic benefits provided by the outsourcing strategy and to what degree the strategic risks determine the manager's attitude toward outsourcing. The results indicate that tactical benefits are perceived the most. The most perceived strategic risks are those related to the loss of differentiation and control over the activities. The findings indicate that the manager's positive perception of the tactical benefits positively influences his/her attitude about outsourcing, and that the greater the perception of strategic risks, the less positive the attitude toward outsourcing will be.

Purpose The purpose of this study is to examine the levels of the main hotel outsourcing activities to identify the factors that determine the use of external suppliers for these activities. Design/methodology/approach A model was developed that analyzes the relationship between competitive advantage and outsourcing and how the relationship between competitive advantage and activity performance is affected by whether an activity is outsourced or not. Moreover, the study builds a matrix called “outsourcing and competitive advantage” where each of the activities can be placed. The study was carried out with a representative sample of hotels in a tourist destination, analyzing 12 activities from different departments in the hotels. Findings The study results indicate that there is a positive relationship between the competitive advantage of an activity and its outcome. In addition, the findings show that the relationship between competitive advantage and activity performance is stronger when the activity is developed internally than when it is outsourced. The study supports a negative relationship between the degree of outsourcing an activity and its competitive advantage. In addition, the findings showed that a change in the way of managing the outsourcing is determined by its performance. Practical implications This study aims to help managers make decisions about outsourcing by considering the perspective of the competitive advantage. Each hotel can situate the activities in the matrix created and compare itself to the sector mean for a strategic positioning of the outsourcing. Originality/value Most studies analyze asset specificity as a key variable; however, the competitive advantage has not been used in previous studies, in spite of being a better defined variable in the literature. This study classifies the activities into core and non-core and establishes their relationship with outsourcing. It also studies how the way of managing an activity (outsourcing or in-house) moderates the relationship between competitive advantage and performance. These aspects have not been analyzed in the literature..

To estimate the correlation between indices of diet quality (DQIs), insulin sensitivity (QUICKI) and resistance (HOMA-IR), waist circumference (WHR) and body mass (BMI) and the alleles and genotypes of the TJP1 SNP rs2291166 and the VNTR of ATXN2 in adolescent patients.The study enrolled 85 subjects aged 10-20years, from the city of Tuxtepec, Oaxaca, Mexico, recruited in the period 2017-2018. DQIs, BMI, WHR, HOMA-IR, QUICKI, and diet quality index were measured. The rs2291166 polymorphism in TJP1 was determined by allele-specific PCR and the (CAG)n expansion in ATXN2 was determined by hot start PCR. PCR products were analyzed using 8% PAGE electrophoresis and silver nitrate staining.A correlation was found of indices DQIs, HOMA-IR, WHR and BMI with the heterozygous genotype of the TJP1 SNP rs2291166 and the long and short repeats of the ATXN2 CAG repeat in obese adolescent patients. A very strong positive correlation was seen between the TJP1 SNP and the HOMA-IR index (P.05). A positive correlation was also found between the ATXN2 CAG repeat and the QUICKI index (P=.000) (P.05), while the DQIs index correlated more closely with BMI and WHR.DQIs, TJP1 SNP rs2291166, and ATXN2 CAG repeat are determinants of obesity-related risk parameters such as BMI, WHR, QUICKI, and HOMA-IR in the adolescent population analyzed.

The objective of this article was to analyze the indications for the proper selection of Onlay adhesive ceramic restorations, providing a step-by-step clinical protocol. Biomechanical principles based on morphological considerations and geometric terms must be present for the careful preparation of Onlay-type cavities. Concepts about cavitary preparations are discussed under essential conditions in the preservation of healthy dental tissue, without compromising the functional and aesthetic results over time. The author's suggestion is to respect and follow in a timely manner each of the steps applied in this restorative clinical protocol, to improve the final outcome of the restoration. El objetivo de este artículo es analizar las indicaciones para la selección adecuada de restauraciones parciales de cerámica adhesiva tipo Onlay, proporcionando el protocolo clínico paso a paso para su correcta aplicación. Principios biomecánicos basados en consideraciones morfológicas y términos geométricos, deberán estar presentes para la cuidadosa preparación de cavidades tipo Onlay. Se discuten conceptos sobre las preparaciones cavitarias bajo condiciones esenciales en la preservación de tejido dental sano, sin compromiso de cúspides de soporte o vertientes que comprometan el resultado final de la restauración en condiciones funcionales y estéticas debidamente planificadas. La sugerencia del autor es respetar y seguir de forma puntual cada uno de los pasos aplicados en el protocolo clínico restaurador, para mejorar el resultado final de las restauraciones en los casos clínicos personalizados.

Background Clinical practice guidelines are tools that have been able to streamline decisions made in health issues and to decrease the gap between clinical action and scientific evidence. Objective The objective of the study is to share the experience in the development and to update the guidelines by the Sistema Nacional de Salud de Mexico. Material and methods The methodology in the development of the guidelines consists of 5 phases: prioritisation, establishment of work groups, development by adoption of international guidelines of de novo, validation and integration in the Master catalogue of clinical practice guidelines for its dissemination. Results The Master catalogue of clinical practice guidelines contains 664 guidelines, distributed in 42% Internal Medicine, 22% Surgery, 24% Paediatrics and 12% Gynaecology. From the total of guidelines coverage is granted at an 85% of the Universal catalogue of health services , an 84% of the Catastrophic expenses protection fund and a 61% of the XXI Century Medical Insurance of the National Commission of Social Protection in Health. Discussion The result is the sum of a great effort of coordination and cooperation between the institutions of the Sistema Nacional de Salud, political wills and a commitment of 3477 health professionals that participate in guidelines’ development and update. Conclusion Master catalogue guidelines’ integration , diffusion and implantation improve quality of attention and security of the users of the Sistema Nacional de Salud.

Giant squid (Dosidicus gigas) proteins have appropriate functional properties, albeit of smaller magnitude in comparison to other marine species. Therefore, this research characterizes the ultrasound-induced (20 kHz; 20 and 40% amplitude; 0, 1, 3 and 5 min) changes to the physicochemical and foaming properties of mantle proteins. The changes in pH, electrophoretic profile, viscosity, surface hydrophobicity, particle size and zeta potential, as well as foaming capacity and stability were evaluated. A slight decrease (p ≥ 0.05) in the pH occurred as the ultrasound time increased. While no changes in SDS-PAGE (reducing and non-reducing) were detected, native PAGE revealed new bands. Ultrasound increased the viscosity and surface hydrophobicity, and decreased the particle size and net surface charge. Moreover, foaming capacity was improved and foaming stability was maintained at 100% for 1 h. Therefore, the application of ultrasound represents an alternative to improve the foaming properties.

The number of left ventricular assist device implants has increased significantly in the last decade. Left ventricular assist device (LVAD) optimization, trouble-shooting complications, and surgical planning require a multi-modality imaging approach. Echocardiography remains the imaging modality of choice, particularly for physiological evaluation but accurate anatomical evaluation of the entirety of the LVAD is often challenging if not impossible. Cardiac computed tomography (CCT) offers additional information that is valuable in taking care of these complex patients. The purpose of this review is to understand the nuances of LVAD imaging and areas where CCT can aid LVAD evaluation and management. CCT has a well-established role in trouble-shooting complications particularly inflow and outflow cannula-related anatomic complications from suction and kinking. Even though the literature is scarce, there is evolving data to suggest that adverse inflow and outflow cannula positions may result in unfavorable outcomes. There is more interest in novel mechanisms of device implantation and planning for which data set from CCT is ideal. Functional evaluation of the right ventricle with CCT is becoming more sophisticated and maybe particularly useful in this patient population. Development in CCT technology has helped minimize safety concerns and improved image quality with reduction in LVAD-related artifacts. CCT is an important adjunct modality to echocardiography for patients with LVAD. Information obtained from CCT may help our understanding of LVAD and in turn help reduce and managed LVAD-related complications.

In this study, a research model investigates the influence of various factors of the outsourcing relationship that condition partnership quality. The factors considered as determinants of outsourcing partnership quality are the strategic benefits and the degree of outsourcing. Partnership quality is based on relationships governed by confidence, commitment, business understanding, shared benefits and risks, and conflict resolution. The model also studies the influence of the partnership quality between the supplier and the hotel on the outsourcing performance, considered from the financial, strategic, and overall satisfaction perspectives. To test the hypotheses, this study used the Partial Least Squares (PLS) technique with a sample of managers in an important tourist destination in Spain. The results of the study confirm that the strategic benefits and the degree of outsourcing perceived by the manager are determinant factors of the quality of the outsourcing partnership. In addition, they show that closer relationships with service suppliers imply greater outsourcing performance. Finally, implications for theory and practice are discussed.

The study analyzes whether the strategic orientation of the firm, measured in six dimensions, influences the level of outsourcing. It also analyzes whether outsourcing has an impact on organizational performance from financial and non-financial perspectives. To do so, an important European tourist destination is analyzed. The findings suggest that the majority of the strategic dimensions influence the hotel’s level of outsourcing. The defensiveness and proactive dimensions are positively related to the level of outsourcing, whereas the competitive analysis and competitive aggressiveness dimensions influence it negatively. In addition, the riskiness dimension has a positive influence, whereas the dimension related to futurity does not influence the level of outsourcing. A positive and significant relationship is found between outsourcing and financial performance, whereas for non-financial performance, the relationship is not significant.

Currently there is controversy in the literature about clinical and adhesive effectiveness with respect to adhesive systems aimed to root reinforcement. Thus, the objective of this study was to evaluate the Push-Out bond strength between the Rebilda® post system and the intraradicular dentine. Thus, 28 unirradicular teeth were used, cut and standardized in 16 mm. The root segments were submitted to endodontic treatment; and then randomly divided into two groups, Group 1 (n = 14): Rebilda® DC + Futurabond DC; Group 2 (n = 14): RelyX ARC + Adper Scothbond Multipurpose Plus. Ten specimens from each group were submitted to the Push-Out Test. The remaining 4 specimens from each group were prepared for Scanning Electron Microscopy (SEM) in order to evaluate the formation of resinous extensions at the post-cement-dentin interface. Group 2 showed better results when compared to Group 1 regarding bond strength and in formation of resinous extensions or tags, but there was no statistically significant difference (p>0.05). It was concluded that the REBILDA® Post System promotes adequate bond strength to intraradicular dentin.

BACKGROUND: Prediction of neonatal respiratory morbidity may be useful to plan delivery in complicated pregnancies. The limited predictive performance of the current diagnostic tests together with the risks of an invasive procedure restricts the use of fetal lung maturity assessment. OBJECTIVE: The objective of the study was to evaluate the performance of quantitative ultrasound texture analysis of the fetal lung (quantusFLM) to predict neonatal respiratory morbidity in preterm and early-term (

Cooking jumbo squid (Dosidicusgigas) muscle produces high organic-matter effluents, potentially pollutant for the environment. Effluent composition and physicochemical properties of solids recovered by freeze drying and spray drying were evaluated after being ultrafiltrated through 30 and 1 kDa cut-off membranes. Ultrafiltration reduced chemical and biochemical oxygen demands (99.8% and 99.4%, respectively). Hue angle and whiteness index were affected (p

Background: The use of sagittal abdominal diameter (SAD) has been proposed for screening cardio-metabolic risk factors; however, its accuracy can be influenced by the choice of thresholds values. Aim: To determine the SAD threshold values for cardio-metabolic risk factors in Mexican adults; to assess whether parallel and serial SAD testing can improve waist circumference (WC) sensitivity and specificity; and to analyze the effect of considering SAD along with WC and body mass index (BMI) in detecting cardio-metabolic risk. Methods: This cross-sectional study was conducted during 2012-2014 in Northeast Mexico (n = 269). Data on anthropometric, clinical, and biochemical measurements were collected. Sex-adjusted receiver-operating characteristic curves (ROC) were obtained using hypertension, dysglycemia, dyslipidemia and insulin resistance as individual outcomes and metabolic syndrome as a composite outcome. Age-adjusted odds ratios and 95% confidence intervals (CI) were estimated using logistic regression. Results: The threshold value for SAD with acceptable combination of sensitivity and specificity was 24.6 cm in men and 22.5 cm in women. Parallel SAD testing improved WC sensitivity and serial testing improved WC specificity. The co-occurrence of high WC/high SAD increased the risk for insulin resistance by 2.4-fold (95% CI: 1.1-5.3), high BMI/high SAD by 4.3-fold (95% CI: 1.7-11.9) and SAD alone by 2.2-fold (95% CI: 1.2.-4.2). Conclusions: The use of SAD together with traditional obesity indices such as WC and BMI has advantages over using either of these indices alone. SAD may be a powerful screening tool for interventions for high-risk individuals. Introducción: el diámetro sagital del abdomen (SAD) se ha usado para detectar factores de riesgo cardiometabólicos; su precisión se ve afectada por los valores de corte. Objetivo: determinar valores de corte para factores de riesgo cardiometabólicos en mexicanos adultos; evaluar la sensibilidad y especificidad cuando se utiliza en serie o en paralelo con la circunferencia de la cintura (WC); y analizar el uso del SAD individualmente o junto a WC o el índice de masa corporal (IMC) para detectar factores de riesgo cardiometabólicos. Métodos: en forma transversal, de 2012 a 2014 se estudiaron 209 sujetos provenientes del noreste mexicano. Se recopilaron datos antropométricos, clínicos y bioquímicos. Se construyeron curvas ROC ajustadas por sexo utilizando como resultado individual hipertensión, disglicemia y resistencia a la insulina y como resultado compuesto, el síndrome metabólico. Se calcularon razón de momios e intervalos de confianza (IC 95%) mediante regresión logística. Resultados: los valores de corte fueron 24,6 cm en hombres y 22,5 cm en mujeres. El SAD en paralelo con la WC mejoró sensibilidad y en forma seriada, la especificidad de WC. La coocurrencia de WC y SAD por encima de los rangos incrementó el riesgo para resistencia a la insulina 2,4 veces (95% CI: 1,1-5,3); BMI y SAD elevados, 4,3 veces (95% CI: 1,7-11,9) y SAD individualmente, 2,2 veces (95% CI: 1,2-4,2). Conclusiones: utilizar el SAD junto a índices tradicionales de obesidad (WC y BMI) tiene ventajas sobre su uso individual. El SAD puede ser una poderosa herramienta de tamizaje para intervenciones en individuos de alto riesgo.

Quality of fresh Monterey sardine (Sardinops sagax caeurela) muscle intended for canning was assessed in a local Mexican plant. Postharvest and processing times and temperatures were monitored at five different processing stages, in order to evaluate their impact on product quality and to compare their biochemical vs. their chronological age. Postmortem muscle spoilage indices were analysed (pH, nitrogen from total volatile bases, trimethylamine, histamine, peroxide value, and thiobarbituric acid-reactive substances) and the K value was analysed as the freshness indicator. Inadequate temperature increments were detected during the canning process. Spoilage indices remained constant throughout the process, indicating that no deterioration occurred in the raw material. Concerning the K value, although sardine showed a good quality for canning, its freshness reduction occurred three times faster than would otherwise occur under optimum handling conditions (0 °C), thus affecting (increasing) its biochemical age. Actual sardine management and treatment by the processor require better control during the canning process, thus reducing their impact on the freshness and biochemical age of sardine intended for this process.

This paper presents the mantisGRID project, an interinstitutional initiative from Colombian medical and academic centers aiming to provide medical grid services for Colombia and Latin America. The mantisGRID is a GRID platform, based on open source grid infrastructure that provides the necessary services to access and exchange medical images and associated information following digital imaging and communications in medicine (DICOM) and health level 7 standards. The paper focuses first on the data abstraction architecture, which is achieved via Open Grid Services Architecture Data Access and Integration (OGSA-DAI) services and supported by the Globus Toolkit. The grid currently uses a 30-Mb bandwidth of the Colombian High Technology Academic Network, RENATA, connected to Internet 2. It also includes a discussion on the relational database created to handle the DICOM objects that were represented using Extensible Markup Language Schema documents, as well as other features implemented such as data security, user authentication, and patient confidentiality. Grid performance was tested using the three current operative nodes and the results demonstrated comparable query times between the mantisGRID (OGSA-DAI) and Distributed mySQL databases, especially for a large number of records.

The Mexican ballad, or corrido is often considered a genre that expresses the notion of "truth" as perceived by its authors and consumers. This essay offers a reading of the corrido that denies this idea of transparency while looking at what the corrido itself contributes to its own definition. First we look at various popular conceptions of what the corrido is thought to accomplish, then we offer an analysis of the self-referential ballad by Los Tigres del Norte aptly titled "El corrido." It is here that, when coupled with instances of metafictional commentary found in other ballads, the breakdown and contradiction of the corrido as vessel of memory shows its own internal fissures. Once this inconsistency is established, we focus on the most popular and conflictive sub-genre of the Mexican ballad, the narco-ballad or narcocorrido. By interpreting the lyrics of various narcocoriddos, we further underscore how this musical form breaks with the journalistic fact finding discourse found in traditional corridos. The concluding section looks to testimonial writing as a comparable genre that is also framed in truth claims in order to establish a hypothetical response to the need for believing the corrido as repository of truth.

One of the major challenges with the use of computed tomography (CT) is to establish the proper tradeoff between radiation dose and image quality. Imaging phantoms are a primary tool that can be used to optimize acquisition protocols without exposing the patients to any unnecessary risk. The purpose of this work was to develop a flexible and low cost imaging phantom to be used for CT optimization. A phantom container made of acrylic and with an elliptical shape was built. A scaffold to insert up to 9 samples with materials of radiological relevance was included within the phantom. Samples of iodinated contrast agent and bone-like material (calcium chloride) were inserted to the phantom. For experimentation two 64-slice systems were used: a dual-source and a conventional single-source CT systems. Imaging protocols with tube potential ranging from 80 to 140 kVp were used. Image noise, contrast, contrast-to-noise ratio (CNR) and figure of merit were calculated in order to assess the performance of the systems at the various acquisition schemes. A strong linear relationship (R2>0.95 in all cases) was found between iodine and calcium materials at different concentrations relative to the CT numbers. This was the case at all tube potentials evaluated and independent of the CT system. At lower tube potential values image contrast increased but image noise also increased. When evaluating a dose-weighted CNR, it was found that the lower kVp provided the most CNR per dose. In conclusion, the development of a low cost imaging phantom which can be used for CT protocols was demonstrated. Experimental evaluations of the phantom across CT protocols with several acquisition parameters and different vendors were performed. It was also demonstrated that this phantom allows to evaluate these systems (and corresponding protocol) performance by relating both achievable CNR and scanner radiation output.

One of the most recent advances in computed tomography is the use of dual energy (DECT). However, this technique typically requires high-end CT scanners. The purpose of this work was the implementation of a protocol that can be used to perform dual energy acquisition with a single source CT scanner (DE-SSCT) by performing two consecutive scans with different tube potential. A semi-anthropomorphic phantom was used. The phantom contained samples of iodine and calcium, and was scanned using both a SSCT and a dual source CT (DSCT). The DSCT system was operated in conventional SSCT mode (ie using only one source), but also in dual-energy mode (ie using both sources) for validation of the proposed approach. The proposed DE-SSCT approach partitioned the dose for each of the two consecutive scans, such that the volume CT dose index (CTDIvol) matched that of a routine SSCT examinations performed at 120 kVp. To characterize the performance of DECT, voxel by voxel CT number ratio (CTR) values between the CT numbers at high and low energy were calculated. Paired t-student test were used to compare mean CTR values. The CTR values for calcium and iodine obtained with the DSCT system operated in dual-energy mode were 1,69 and 2,10; and 1,68 and 2,05 using the DSCT system but with the proposed DE-SSCT method. CTR differences were statistically significant (p

The purpose of this study is to investigate how well model observer can correlate with human observer in the lesion detection and localization task when the location of lesion is uncertain in CT imaging. A 35 × 26 cm oblong-shaped water phantom was scanned with and without two cylindrical rods (3 mm and 5 mm diameters) to simulate lesions with - 15HU contrast. Scans were repeated 100 times with the rods and 100 times without for each of 4 dose levels. Signal and background images were generated by selecting ROIs with 128x128 pixels, with the location of signal in each ROI randomly distributed. Human observer studies were conducted as three medical physicists identified the presence or absence of lesion, indicated the lesion location in each image and scored confidence level with a 6-point scale. ROC curves were fitted and area under curve (AUC) was calculated. The same data set was also analyzed using a Channelized Hottelling model observer with Gabor channels. Internal noise was added to the test variables for model observer study. AUC of ROC and LROC curves were calculated using non-parametric approach. The performance of human observer and model observer was compared. The Peason's product-moment correlation coefficients were 0.994 and 0.998 for 3mm and 5mm diameter lesions in ROC analysis and 0.987 and 0.999 in LROC analysis, indicating that model observer performance was highly correlated with the human observer performance for different size of lesions and different dose levels when signal location is uncertain. These results provide the potential of using model observer that correlates with human observer to assess CT image quality, optimize scanning protocol and reduce radiation dose.

The objective of this study was to investigate the effect on radiation dose and image quality of the use of additional spectral filtration for dual-energy CT using dual-source CT (DSCT).A commercial DSCT scanner was modified by adding tin filtration to the high-kV tube, and radiation output and noise were measured in water phantoms. Dose values for equivalent image noise were compared between the dual-energy mode with and without tin filtration and the single-energy mode. To evaluate dual-energy CT material discrimination, the material-specific dual-energy ratio for calcium and that for iodine were determined using images of anthropomorphic phantoms. Data were additionally acquired from imaging a 38-kg pig and an 87-kg pig, and the noise of the linearly mixed images and virtual noncontrast images was compared between dual-energy modes. Finally, abdominal dual-energy CT images of two patients of similar sizes undergoing clinically indicated CT were compared.Adding tin filtration to the high-kV tube improved the dual-energy contrast between iodine and calcium as much as 290%. Data from our animal study showed that tin filtration had no effect on noise in the dual-energy CT mixed images but decreased noise by as much as 30% in the virtual noncontrast images. Virtual noncontrast images of patients acquired using 100 and 140 kV with added tin filtration had improved image quality relative to those generated using 80 and 140 kV without tin filtration.Tin filtration of the high-kV tube of a DSCT scanner increases the ability of dual-energy CT to discriminate between calcium and iodine without increasing dose relative to single-energy CT. Furthermore, the use of 100- and 140-kV tube potentials allows improved dual-energy CT imaging of large patients.

The purpose of this paper is to present a new image reconstruction algorithm for dynamic data, termed non-convex prior image constrained compressed sensing (NC-PICCS). It generalizes the prior image constrained compressed sensing (PICCS) algorithm with the use of non-convex priors. Here, we concentrate on perfusion studies using computed tomography examples in simulated phantoms (with and without added noise) and in vivo data, to show how the NC-PICCS method holds potential for dramatic reductions in radiation dose for time-resolved CT imaging. We show that NC-PICCS can provide additional undersampling compared to conventional convex compressed sensing and PICCS, as well as, faster convergence under a quasi-Newton numerical solver.

Optimal noise control is important for improving image quality and reducing radiation dose in computed tomography. Here we investigated two image space based nonlinear filters for noise reduction: the bilateral filter (BF) and the nonlocal means (NLM) algorithm. Images from both methods were compared against those from a commercially available weighted filtered backprojection (WFBP) method. A standard phantom for quality assurance testing was used to quantitatively compare noise and spatial resolution, as well as low contrast detectability (LCD). Additionally, an image dataset from a patient's abdominal CT exam was used to assess the effectiveness of the filters on full dose and simulated half dose acquisitions. We found that both the BF and NLM methods improve the tradeoff between noise and high contrast spatial resolution with no significant difference in LCD. Results from the patient dataset demonstrated the potential of dose reduction with the denoising methods. Care must be taken when choosing the NLM parameters in order to minimize the generation of artifacts that could possibly compromise diagnostic value.

Objetivo: Comprobar los datos urodinámicos en las pacientes con infecciones urinarias recidivantes en orden a demostrar una causa que las justifique. Métodos: Se realiza un estudio transversal comparativo en una serie de 114 mujeres, de edad media 51.9 anos (desviación típica: 23.5 anos), divididas en dos grupos de 57 mujeres cada uno: grupo con infecciones urinarias recidivantes (ITU), y grupo sin infecciones urinarias recidivantes (no ITU). A las pacientes se les sometió a interrogatorio clínico, exploración física y estudio videourodinámico. Los datos fueron almacenados en una base de datos Access y posteriormente importados al programa de análisis estadísticos SPSS. Se aplicaron el test exacto de Fisher, Chi-Cuadrado de Pearson, y t de Student. Se calculo la curva ROC. Se elaboro un modelo multivalente de regresion logistica. Resultados: Únicamente se demostraron diferencias significativas en los valores del flujo miccional máximo (menor en el grupo ITU), volumen residuo postmiccional (mayor en el grupo ITU), y presión de la contracción involuntaria del detrusor (menor en el grupo ITU). No obstante, la unica variable independiente fue el residuo postmiccional, constituyéndose las dos restantes en variables dependientes. El punto de corte ideal entre residuo postmiccional e infección urinaria correspondió a un residuo de 48.5 ml. El coeficiente de determinación del modelo fue de 0.13. No se demostraron relaciones significativas de las infecciones urinarias con (entre otras): la presencia y grado de cistocele, asi como con la hiperactividad del detrusor e incontinencia urinaria de esfuerzo. Conclusiones: El residuo postmiccional explicaría el 13 % de las infecciones urinarias recidivantes de la mujer. El resto se debería a otros factores no incluidos en el modelo.

he aim of this In Vivo study was to evaluate the influence of the cavosurface angle (with bevel, and no preparation), of direct composite resin restorations in previous fractured teeth after 4 years of clinical performance. The restorations were performed by a single operator, following a restorative standardized protocol. For the study were selected 24 upper central incisors with fracture or with class IV restorations with an indication of replacement. According to the restorative technique, the teeth were divided into 2 groups: group I (n = 12) Class IV Restorations with a bevel preparation technique; and group II (n = 12) Class IV Restorations performed with no preparation. The restorations were evaluated at 7 days and 4 years, by two examiners, previously calibrated using modified USPHS criteria. After 4 years, two restorations were excluded, representing 22 restorations (11 with bevel preparation, and 11 without). The Fisher test demonstrates no significant differences between groups (p > 0.05). This study presents clinical evidence that the cavosurface angle configuration does not influence the clinical performance of direct composite resin restorations in fractured teeth. Thus, we recommend no preparation of the cavosurface angle to preserve sound dental tissue based on a Minimally Invasive Dentistry approach. El objetivo de este estudio clínico fue evaluar la influencia del ángulo cavo superficial (con bisel o sin bisel) de restauraciones directas de resina compuesta en dientes anteriores fracturados después de 4 años de desempeño clínico. Las restauraciones se realizaron por un solo operador, siguiendo un protocolo estandarizado. Para el estudio se seleccionaron 24 incisivos centrales superiores con fractura o con restauraciones clase IV con una indicación substitución. De acuerdo con la técnica de restauración, las piezas dentales se dividieron en 2 grupos: grupo I (n = 12) restauraciones Clase IV con una técnica de preparación con bisel; y grupo II (n = 12) restauraciones Clase IV sin ninguna técnica. Las restauraciones se evaluaron a los 7 días y 4 años, por dos examinadores previamente calibrados utilizando criterios USPHS modificados. Después de 4 años, se excluyeron dos sujetos de estudio, lo que representa 22 restauraciones (11 restauraciones con preparación en bisel, y 11 sin preparación de bisel). La prueba de Fisher demostró que no existen diferencias significativas entre los grupos (p> 0,05). Este estudio presenta evidencia clínica demostrando que la configuración del ángulo cavo superficial no influye en el desempeño clínico de las restauraciones de resina compuesta directas en dientes anteriores fracturados. Por lo tanto, se recomienda evitar la preparación con bisel del ángulo cavo superficial, con el objetivo de preservar tejido dental sano basado en el enfoque de la Odontología Mínimamente Invasiva.

La violencia doméstica masculina contra la pareja hetero-sexual (VDMCPH) es un tema que se ha investigado de manera sistemática en México en los últimos 15 años. El propósito de este trabajo es reflexionar sobre los aportes hechos sobre el tema en el país. La discusión está centrada en tres grandes ámbitos temáticos: la magnitud del fenómeno considerando sus implicaciones teóricas, metodológicas y técnicas; la relación de la violencia con diversos factores; y las consecuencias del ejercicio de la VDMCPH en la propia mujer. La exposición está guiada por los aportes hechos en estudios cuantitativos y complementada con la visión cualitativa.

The present study was performed in order to identify the cost of drugs used without documenting them in the patients' file and the wastage of drugs in a pediatric anesthesiology ward. In a prospective, blinded, observational design, drug utilization of 610 consecutive patients, undergoing an elective or emergency surgical procedure was evaluated. The number of undocumented drugs per 100 requested units and the number of wasted drugs per 100 requested units were computed and multiplied by its corresponding unitary cost. The median undocumented cost was 92.4 US dollars (95% CI 17.2-216.6 dollars) per 100 requested units. Succinylcholine (40 mg/2 mL) was the main undocumented drug; its use was not documented in approximately 50% cases in which this neuromuscular blocking agent was requested. However, rocuronium and nalbuphine had the highest unjustified cost, 770.6 dollars and 847.0 dollars per 100 requested units, respectively. Ketorolac, diclofenac, metamizol, furosemide, methylprednisolone, sodium bicarbonate, and cisatracurium were requested and documented. The median cost of wasted drug was 141.8 dollars (95% CI 55.8-448.2 dollars) per 100 requested drugs. More than 80% of adrenaline, naloxone, flunitrazepam, ephedrine, and cisatracurium were wasted. However, the highest cost of wasted drugs was for ondansetron, cisatracurium, methylprednisolone, and rocuronium. The uncontrolled availability and use of drugs may represent an important amount of resources wasted without any awareness of the staff in a department of pediatric anesthesia.

Background In Mexico, guidelines for fasting periods, or any audits on this topic are unavailable, and therefore the attitudes of anesthesiologists for recommending preoperative fasting periods are unknown. Material and methods The study was a cross-sectional survey of anesthesiologists subscribed to the Annual Updated Course, organized by the Sociedad Mexicana de Anestesiologia in 2000. The response rate was 31.4%. Results Most respondents were general anesthesiologists, with 5 or more years experience in a clinical post, were working in both public and private hospitals, and were performing anesthetic procedures on both pediatric and adult patients and in both ambulatory and hospitalized patients. Approximately 23% of the respondents considered natural fruit juices to be clear liquids. For a pediatric patient ingesting breast milk 1 h before undergoing a surgical procedure, 45% thought that surgery should be delayed for 3h, followed by those delaying the surgical procedure for 6 to 8 h. Our results show that more than 50% of the anesthesiologists had better defined attitudes for fasting milk and clear liquids in patients of 6 month or under than for older children and adults. However, due to the poor definition or pre-operative fasting, using clear liquids, in all other patient groups, several patients are allowed to go without oral clear liquids administration for prolonged periods. Conclusion Preoperative fasting periods recommended by Mexican anesthesiologists differ from international guidelines.

Purpose: Iterative reconstruction (IR) offers notable advantages in computed tomography (CT). However, its performance characterization is complicated by its potentially nonlinear behavior, impacting performance in terms of specific tasks. This study aimed to evaluate the performance of IR with both task-specific and task-generic strategies. Methods: The performance of IR in CT was mathematically assessed with an observer model that predicted the detection accuracy in terms of the detectability index (d′). d′ was calculated based on the properties of the image noise and resolution, the observer, and the detection task. The characterizations of image noise and resolution were extended to accommodate the nonlinearity of IR. A library of tasks was mathematically modeled at a range of sizes (radius 1–4 mm), contrast levels (10–100 HU), and edge profiles (sharp and soft). Unique d′ values were calculated for each task with respect to five radiation exposure levels (volume CT dose index, CTDIvol: 3.4–64.8 mGy) and four reconstruction algorithms (filtered backprojection reconstruction, FBP; iterative reconstruction in imaging space, IRIS; and sinogram affirmed iterative reconstruction with strengths of 3 and 5, SAFIRE3 and SAFIRE5; all provided by Siemens Healthcare, Forchheim, Germany). The d′ values were translated into the areas under the receiver operating characteristic curve (AUC) to represent human observer performance. For each task and reconstruction algorithm, a threshold dose was derived as the minimum dose required to achieve a threshold AUC of 0.9. A task-specific dose reduction potential of IR was calculated as the difference between the threshold doses for IR and FBP. A task-generic comparison was further made between IR and FBP in terms of the percent of all tasks yielding an AUC higher than the threshold. Results: IR required less dose than FBP to achieve the threshold AUC. In general, SAFIRE5 showed the most significant dose reduction potentials (11–54 mGy, 77%–84%), followed by SAFIRE3 (7–36 mGy, 50%–61%) and IRIS (6–26 mGy, 37%–50%). The dose reduction potentials highly depended on task size and task contrast, with tasks of lower contrasts and smaller sizes, i.e., more challenging tasks, indicating higher dose reductions. Softer edge profile showed higher dose reduction potentials with SAFIRE3 and SAFIRE5, but not with IRIS. The task-generic comparison between IR and FBP demonstrated the overall superiority of IR performance, as IR allowed a larger percent of tasks to exceed the threshold AUC: IRIS, 8%–12%; SAFIRE3, 10%–16%; and SAFIRE5, 20%–33%. The improvement with IR was generally more pronounced at lower dose levels. Conclusions: Expanding beyond traditional contrast and noise based assessments of IR, we performed both task-specific and task-generic evaluations of IR performance. The task-specific evaluation demonstrated the dependency of IR’s dose reduction potential on task attributes, which can be employed to optimize IR for clinical indications with specific range of size and contrast. The task-generic evaluation demonstrated IR’s overall superiority over FBP in terms of the range of tasks exceeding a threshold performance level, which can be employed for general comparisons between algorithms.

Background Several neuromuscular blocking (NMB) agents are available for clinical use in anesthesia. The present study was performed in order to identify preferences and behaviors of anesthesiologists for using vecuronium, rocuronium or other NMB agents in their clinical practice. Material and methods The cross-sectional survey was applied at the Updated Course of the Colegio Mexicano de Anestesiología performed last year. Of 989, 282 (28.5%) surveys were returned. Results Most anesthesiologists were working at both public and private hospitals, performed anesthetic procedures for hospitalized and ambulatory patients, and anesthetized children as well as adults. Respondents did not consider mechanomyography as the gold standard method for neuromuscular monitoring. The T25 was not recognized as a pharmacodynamic parameter that represents the clinical duration of the neuromuscular block. Most answered that vecuronium induces less histamine release than rocuronium, had never used any neuromuscular monitor, did not know the cost of vecuronium and rocuronium, and preferred rocuronium in multiple-sampling vials and vecuronium in either a vial for single or multiple sampling. Rocuronium was preferred for emergency surgery in patients with full stomach only. Almost all of anesthesiologists that conserve the unused drug did it without refrigeration and more than 30% conserve the unused drug in one syringe for further use. Conclusion Vecuronium was preferred for most clinical situations, and the decision for this choice was not based on costs. Storage of unused drugs without refrigeration in a single syringe for purpose of future use in several patients represented a dangerous common practice.