148 research outputs found
A flexible cooking zone composed of partially overlapped inductors
Domestic induction cookers are evolving from fixed cooking areas to flexible surfaces in such a way that the pot can be placed at any position. This implies the use of a larger number of reduced-sized inductors, which present a lower efficiency. As a solution to increase the efficiency while maintaining the flexibility, we propose the use of partially overlapped inductors of a larger size. This concept is currently in use in wireless power transfer systems, where the transmitter arrangement consists of several overlapped coils. The aim of this paper is to evaluate this concept applied to domestic induction heating appliances, with special emphasis in analyzing the effects of introducing the multicoil system with dissipative media. Moreover, the losses in the winding will be studied in detail. The system will be prototyped and tested, delivering up to 3.7 kW
Analysis and design of tubular coils for wireless inductive power transfer systems
We evaluate copper tubes as alternative of litz wire for planar coils of inductive power transfer (IPT) systems. For this purpose, a design methodology focused on maximizing the product of the magnetic coupling and the quality factor is proposed. The methodology is based on a combination of FEA simulations and analytical calculations of the skin and proximity losses in the tube. Analytical calculations are based on solutions of Maxwell''s equations for a tubular geometry. These solutions are oriented to extract both skin and proximity losses in the tube. Performance of a prototype of 1.5 kW is evaluated and compared with a conventional litz-wire implementation
Analytical solution of the induced currents in multilayer cylindrical conductors under external electromagnetic sources
We present a closed-form solution for the induced losses in round conductors consisting of several concentric layers. The geometry under study corresponds to an infinitely-long and isolated multilayer cylinder where layers can have different electromagnetic properties and the number of layers is not restricted. The multilayer conductor is under an external time-varying magnetic field which induces currents and, accordingly, generates Joule dissipation. Total induced losses are obtained by integrating the losses of each layer. Mathematical expressions of the current distribution in each layer are derived from the solution of Maxwell''s equations. These expressions consist of a combination of Bessel functions of different kinds and orders. The current distribution in a particular layer not only depends on the properties of the layer but also on the properties of the rest of layers. Consequently, matrix formalism is adopted for describing current distribution of layers. Matrix description is numerically solved and results are compared with finite element simulations for different arrangements and cases
Estudio de las lesiones neoplásicas metacrónicas en el carcinoma colorrectal
Fundamento.
Analizar la frecuencia y las características de las lesiones neoplásicas metacrónicas, carcinomas y adenomas, tras la resección de un cáncer colo-rectal (CCR).
Pacientes y métodos.
Revisamos 382 CCR operados y seguidos mediante colonoscopias completas en dos hospitales de nuestra comunidad. Analizamos las lesiones metacrónicas registradas valorando su localización, momento del diagnóstico, histología, número y tamaño. Estudiamos la frecuencia de adenomas de aparición precoz (12 meses), comparando su tamaño con respecto al resto de lesiones.
Resultados.
La mediana de seguimiento fue de 48 meses (12-112), con 2,74±1,47 colonoscopias/caso. Diagnosticamos 7 cánceres metacrónicos (1,8%), 4 de ellos en estadio I. La mediana de tiempo hasta su diagnóstico fue de 24 meses (13-54). Registramos adenomas metacrónicos en 162 casos (42,4%), sin diferencias entre los dos hospitales: 42,1% vs. 43,8% (p=0,88). Un 6,3% de los pacientes presentaron adenomas avanzados. En 164 casos en que el primer control se efectuó a los 12 meses, la incidencia de adenomas fue del 24%. Los adenomas fueron mayoritariamente únicos (60,8%) y menores de 5 mm (68,5%). En un 55,5% de los casos con pólipos, alguno tenía una localización proximal. El diagnóstico se realizó en la 1ª exploración (56,2%), 2ª (27,8%) ó 3ª (9%). La mediana de tiempo hasta el diagnóstico fue de 21 meses (12-112) para el adenoma simple y de 35 (12-112) para el avanzado.
Conclusiones.
Nuestro seguimiento permitió aplicar un tratamiento teóricamente curativo en la mayoría de los carcinomas metacrónicos diagnosticados. La alta incidencia de adenomas y su frecuente localización proximal hacen necesario un seguimiento con colonoscopias completas, que debería iniciarse al año de la operación y podría pasar a ser menos estricto tras tres exploraciones consecutivas sin pólipos
Estudio de la frecuencia, distribución y rendimiento diagnóstico en las lesiones neoplásicas sincrónicas del carcinoma colo-rectal
ABSTRACT
To analyse the frequency, characteristics and
diagnosis of synchronic neoplastic lesions in colorectal cancer.
A review was carried out of 384 colorectal
cancers, diagnosed through complete colonoscopy and
resected. The synchronic cancers and the characteristics of the
adenomas were determined: number, size, histological type,
dysplasia, as well as their localisation in the colon and with
respect to the carcinoma.
Twenty-eight synchronic cancers were found
(7.3% of the total); 8 developed tumours and 20 malignant
polyps. In 54.4% of the cases there was a synchronic adenoma.
In patients with synchronic lesions, 43% showed an advanced
adenoma. Twenty percent of the synchronic polyps found were
proximal to the splenic flexure; 41% were distal and 38% had
both localisations. Fifty-nine point one percent of the patients
had some adenoma proximal to the cancer, with criteria of
advanced adenoma in 13.9%. The distribution of the adenomas
was more uniformly spread in the cancers with a proximal
localisation (p = 0.038). Seventeen percent of the distal cancers
presented synchronic lesions with a proximal colon localisation
exclusively. Partial endoscopies would diagnose the distal
cancers, but would omit a synchronic adenoma in 42.3% of the
sigmoidoscopies and 40% of the short colonoscopies.
High rates of carcinoma and synchronic
adenomas were registered. We underline the high index of
advanced adenomas and the frequency of synchronic lesions
proximal to the cancer, which is why incomplete colonoscopies,
although allowing the diagnosis of the distal cancer, omit a high
percentage of synchronic adenomas, including advanced
lesions. All of this confirms the need to perform a complete pre-
, intra- and post operational colonoscopy in resectable
colorectal cancer
Portion control tableware differentially impacts eating behaviour in women with and without overweight
Portion control tableware has been described as a potentially effective approach for weight management,
however the mechanisms by which these tools work remain unknown. We explored the processes by which a
portion control (calibrated) plate with visual stimuli for starch, protein and vegetable amounts modulates food
intake, satiety and meal eating behaviour. Sixty-five women (34 with overweight/obesity) participated in a
counterbalanced cross-over trial in the laboratory, where they self-served and ate a hot meal including rice,
meatballs and vegetables, once with a calibrated plate and once with a conventional (control) plate. A subsample of 31 women provided blood samples to measure the cephalic phase response to the meal. Effects of
plate type were tested through linear mixed-effect models. Meal portion sizes (mean ± SD) were smaller for the
calibrated compared with the control plate (served: 296 ± 69 vs 317 ± 78 g; consumed: 287 ± 71 vs 309 ± 79 g
respectively), especially consumed rice (69 ± 24 vs 88 ± 30 g) (p < 0.05 for all comparisons). The calibrated
plate significantly reduced bite size (3.4 ± 1.0 vs 3.7 ± 1.0 g; p < 0.01) in all women and eating rate (32.9 ± 9.5
vs 33.7 ± 9.2 g/min; p < 0.05), in lean women. Despite this, some women compensated for the reduced intake
over the 8 h following the meal. Pancreatic polypeptide and ghrelin levels increased post-prandially with the
calibrated plate but changes were not robust. Plate type had no influence on insulin, glucose levels, or memory
for portion size. Meal size was reduced by a portion control plate with visual stimuli for appropriate amounts of
starch, protein and vegetables, potentially because of the reduced self-served portion size and the resulting
reduced bite size. Sustained effects may require the continued use of the plate for long-term impact
Development and validation of a new methodological platform to measure behavioral, cognitive, and physiological responses to food interventions in real time
To fully understand the causes and mechanisms involved in overeating and obesity, measures of both cognitive and physiological determinants of eating behavior need to be integrated. Effectively synchronizing behavioral measures such as meal micro-structure (e.g., eating speed), cognitive processing of sensory stimuli, and metabolic parameters, can be complex. However, this step is central to understanding the impact of food interventions on body weight. In this paper, we provide an overview of the existing gaps in eating behavior research and describe the development and validation of a new methodological platform to address some of these issues. As part of a controlled trial, 76 men and women self-served and consumed food from a buffet, using a portion-control plate with visual stimuli for appropriate amounts of main food groups, or a conventional plate, on two different days, in a random order. In both sessions participants completed behavioral and cognitive tests using a novel methodological platform that measured gaze movement (as a proxy for visual attention), eating rate and bite size, memory for portion sizes, subjective appetite and portion-size perceptions. In a sub-sample of women, hormonal secretion in response to the meal was also measured. The novel platform showed a significant improvement in meal micro-structure measures from published data (13 vs. 33% failure rate) and high comparability between an automated gaze mapping protocol vs. manual coding for eye-tracking studies involving an eating test (ICC between methods 0.85; 90% CI 0.74, 0.92). This trial was registered at Clinical Trials.gov with Identifier NCT03610776
Idiopathic dilatation of the right atrium. Report of four fetal cases
Introduction: Idiopathic dilatation of the right atrium (IDRA) is a rare anomaly defined as isolated enlargement of the right atrium in the absence of other cardiac lesions or predisposing conditions to cause right atrial (RA) dilatation, especially tricuspid valve diseases..
Modelado numérico de pérdidas en conductores de sección rectangular mediante análisis por elementos finitos
En esta ponencia, se presenta un método para calcular las pérdidas en alterna (incluyendoefecto skin y proximidad) en dispositivos magnéticos planares con sección de conducciónrectangular. Se desarrolla un modelado de pérdidas similar al empleado con conductores desección circular para los conductores anteriormente mencionados. El objetivo es obtener unproceso de diseño adecuado, especialmente para los dispositivos magnéticos implementadosen placa de circuito impreso (PCB). Básicamente, el modelado de pérdidas está basado en lasuperposición de las pérdidas en el conductor (pérdidas de conducción y de proximidad), ytambién en una descomposición ortogonal del campo bajo el que se encuentran losconductores. El número de funciones necesarias para calcular las pérdidas de proximidad sereduce a una, tal y como ocurre en los conductores circulares. Esta función, junto con lafunción que describe las pérdidas de conducción, ambas contienen las dependenciasgeométricas y frecuenciales, son calculadas y tabuladas mediante un Análisis por ElementosFinitos (FEA). El campo magnético se calcula mediante una simulación magnetostática basadaen FEA. De esta forma las pérdidas son obtenidas con una reducción del tiempo de cálculoconsiderable. Finalmente, se han caracterizado varios prototipos para verificar el modelado depérdidas
S-adenosylmethionine regulates MAT1A and MAT2A gene expression in cultured rat hepatocytes: a new role for S-adenosylmethionine in the maintenance of the differentiated status of the liver
Methionine metabolism starts with the formation of S-adenosylmethionine (AdoMet), the most important biological methyl donor. This reaction is catalyzed by methionine adenosyltransferase (MAT). MAT is the product of two different genes: MAT1A, which is expressed only in the adult liver, and MAT2A, which is widely distributed, expressed in the fetal liver, and replaces MAT1A in hepatocarcinoma. In the liver, preservation of high expression of MAT1A and low expression of MAT2A is critical for the maintenance of a functional and differentiated organ. Here we describe that in cultured rat hepatocytes MAT1A expression progressively decreased, as described for other liver-specific genes, and MAT2A expression was induced. We find that this switch in gene expression was prevented by adding AdoMet to the culture medium. We also show that in cultured hepatocytes with decreased MAT1A expression AdoMet addition markedly increased MAT1A transcription in a dose-dependent fashion. This effect of AdoMet was mimicked by methionine, and blocked by 3-deazaadenosine and L-ethionine, but not D-ethionine, indicating that the effect was specific and mediated probably by a methylation reaction. These findings identify AdoMet as a key molecule that differentially regulates MAT1A and MAT2A expression and helps to maintain the differentiated status of the hepatocyte
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