Computer 3D modeling of radiofrequency ablation of atypical cartilaginous tumours in long bones using finite element methods and real patient anatomy

BACKGROUND: Radiofrequency ablation (RFA) is a minimally invasive technique used for the treatment of neoplasms, with a growing interest in the treatment of bone tumours. However, the lack of data concerning the size of the resulting ablation zones in RFA of bone tumours makes prospective planning challenging, needed for safe and effective treatment. METHODS: Using retrospective computed tomography and magnetic resonance imaging data from patients treated with RFA of atypical cartilaginous tumours (ACTs), the bone, tumours, and final position of the RFA electrode were segmented from the medical images and used in finite element models to simulate RFA. Tissue parameters were optimised, and boundary conditions were defined to mimic the clinical scenario. The resulting ablation diameters from postoperative images were then measured and compared to the ones from the simulations, and the error between them was calculated. RESULTS: Seven cases had all the information required to create the finite element models. The resulting median error (in all three directions) was -1 mm, with interquartile ranges from -3 to 3 mm. The three-dimensional models showed that the thermal damage concentrates close to the cortical wall in the first minutes and then becomes more evenly distributed. CONCLUSIONS: Computer simulations can predict the ablation diameters with acceptable accuracy and may thus be utilised for patient planning. This could allow interventional radiologists to accurately define the time, electrode length, and position required to treat ACTs with RFA and make adjustments as needed to guarantee total tumour destruction while sparing as much healthy tissue as possible

Simulation and experimental study of rheological properties of CeO2 – water nanofluid

Open Access. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Metal oxide nanoparticles offer great merits over controlling rheological, thermal, chemical and physical properties of solutions. The effectiveness of a nanoparticle to modify the properties of a fluid depends on its diffusive properties with respect to the fluid. In this study, rheological properties of aqueous fluids (i.e. water) were enhanced with the addition of CeO2 nanoparticles. This study was characterized by the outcomes of simulation and experimental results of nanofluids. The movement of nanoparticles in the fluidic media was simulated by a large-scale molecular thermal dynamic program (i.e. LAMMPS). The COMPASS force field was employed with smoothed particle hydrodynamic potential (SPH) and discrete particle dynamics potential (DPD). However, this study develops the understanding of how the rheological properties are affected due to the addition of nanoparticles in a fluid and the way DPD and SPH can be used for accurately estimating the rheological properties with Brownian effect. The rheological results of the simulation were confirmed by the convergence of the stress autocorrelation function, whereas experimental properties were measured using a rheometer. These rheological values of simulation were obtained and agreed within 5 % of the experimental values; they were identified and treated with a number of iterations and experimental tests. The results of the experiment and simulation show that 10 % CeO2 nanoparticles dispersion in water has a viscosity of 2.0–3.3 mPasPeer reviewedFinal Published versio

Improving Interferometric Null Depth Measurements using Statistical Distributions: Theory and First Results with the Palomar Fiber Nuller

A new "self-calibrated" statistical analysis method has been developed for the reduction of nulling interferometry data. The idea is to use the statistical distributions of the fluctuating null depth and beam intensities to retrieve the astrophysical null depth (or equivalently the object's visibility) in the presence of fast atmospheric fluctuations. The approach yields an accuracy much better (about an order of magnitude) than is presently possible with standard data reduction methods, because the astrophysical null depth accuracy is no longer limited by the magnitude of the instrumental phase and intensity errors but by uncertainties on their probability distributions. This approach was tested on the sky with the two-aperture fiber nulling instrument mounted on the Palomar Hale telescope. Using our new data analysis approach alone-and no observations of calibrators-we find that error bars on the astrophysical null depth as low as a few 10-4 can be obtained in the near-infrared, which means that null depths lower than 10-3 can be reliably measured. This statistical analysis is not specific to our instrument and may be applicable to other interferometers

Soft–bottom sipunculans from San Pedro del Pinatar (Western Mediterranean): influence of anthropogenic impacts and sediment characteristics on their distribution

We analysed the distribution of soft bottom sipunculans from San Pedro del Pinatar (Western Mediterranean). This study was carried out from December 2005 to June 2010, sampling with biannual periodicity (June and December). Physical and chemical parameters of the sediment were analysed (granulometry, organic matter content, pH, bottom salinity and shelter availability). Nine different species and subspecies were identified, belonging to five families. Aspidosiphon muelleri muelleri was the dominant species, accumulating 89.06% of the total abundance of sipunculans. Higher sipunculan abundances were correlated with stations of higher percentage of coarse sand, empty mollusc shells and empty tubes of the serpulid polychaete Ditrupa arietina, where some of the recorded species live. Sediment characteristics played the main role controlling the sipunculans distribution. Anthropogenic impacts could be indirectly affecting their distribution, changing the sediment characteristics. Key words: Sipuncula, Aspidosiphon muelleri, Mediterranean, Anthropogenic impact, Soft–bottom.Se analizó la distribución de los sipuncúlidos de fondos blandos de San Pedro del Pinatar (Mediterráneo occidental). Este estudio se llevó a cabo entre diciembre de 2005 y junio de 2010, muestreando con periodicidad semestral (junio y diciembre). Se analizaron parámetros físicos y químicos del sedimento (granulometría, contenido de materia orgánica, pH, salinidad de fondo y disponibilidad de refugio). Nueve especies y subespecies diferentes fueron identificadas, pertenecientes a cinco familias. Aspidosiphon muelleri muelleri fue la especie dominante, acumulando el 89,06% de la abundancia total de sipuncúlidos. Las mayores abundancias de sipuncúlidos se correlacionaron con las estaciones con mayores porcentajes de arena gruesa, conchas de moluscos vacías y tubos vacíos del poliqueto serpúlido Ditrupa arietina, donde viven algunas de las especies registradas. Las características del sedimento jugaron el papel principal en el control de la distribución de sipuncúlidos. Los impactos antropogénicos podrían estar afectando indirectamente su distribución, cambiando las características del sedimento. Palabras clave: Sipuncúlidos, Aspidosiphon muelleri, Mediterráneo, Impacto antropogénico, Fondos blandos.We analysed the distribution of soft bottom sipunculans from San Pedro del Pinatar (Western Mediterranean). This study was carried out from December 2005 to June 2010, sampling with biannual periodicity (June and December). Physical and chemical parameters of the sediment were analysed (granulometry, organic matter content, pH, bottom salinity and shelter availability). Nine different species and subspecies were identified, belonging to five families. Aspidosiphon muelleri muelleri was the dominant species, accumulating 89.06% of the total abundance of sipunculans. Higher sipunculan abundances were correlated with stations of higher percentage of coarse sand, empty mollusc shells and empty tubes of the serpulid polychaete Ditrupa arietina, where some of the recorded species live. Sediment characteristics played the main role controlling the sipunculans distribution. Anthropogenic impacts could be indirectly affecting their distribution, changing the sediment characteristics. Key words: Sipuncula, Aspidosiphon muelleri, Mediterranean, Anthropogenic impact, Soft–bottom

Improving the light collection efficiency of silicon photomultipliers through the use of metalenses

Metalenses are optical devices that implement nanostructures as phase shifters to focus incident light. Their compactness and simple fabrication make them a potential cost-effective solution for increasing light collection efficiency in particle detectors with limited photosensitive area coverage. Here we report on the characterization and performance of metalenses in increasing the light collection efficiency of silicon photomultipliers (SiPM) of various sizes using an LED of 630 nm, and find a six to seven-fold increase in signal for a 1.3×1.3 mm² SiPM when coupled with a 10-mm-diameter metalens manufactured using deep ultraviolet stepper lithography. Such improvements could be valuable for future generations of particle detectors, particularly those employed in rare-event searches such as dark matter and neutrinoless double beta decay

LASIK monocular en pacientes adultos con ambliopía por anisometropía

ResumenObjetivoDeterminar la eficacia y la seguridad del LASIK en el tratamiento de la ambliopía por anisometropía en pacientes adultos.MétodosSerie de casos. Estudiamos a 12 pacientes adultos ambliopes por anisometropía a los cuales se realizó LASIK monocular de nuestro servicio de Córnea y Cirugía Refractiva. Evaluamos el error refractivo pre y postoperatorio, equivalente esférico (ES), la agudeza visual sin corrección (AVSC) y la agudeza visual mejor corregida (AVMC). La agudeza visual medida por la cartilla de Snellen fue convertida a LogMAR con fines de análisis estadístico.ResultadosLa edad promedio fue de 31.92 (± 12.13) años. El ES preoperatorio promedio en el ojo tratado fue de –3.49 D (± 3.24), el ES promedio del ojo no tratado fue de 0.25 D (± 0.30). La AVSC preoperatoria fue de 1.12 (± 0.3) LogMAR y la AVMC preoperatoria fue 0.31 (± 0.1) LogMAR. El seguimiento promedio fue de 19.1 (rango 6-74) meses. El ES promedio postoperatorio disminuyó a –0.28 (± 0.48). Cinco pacientes (42%) ganaron una línea de visión, un (8%) paciente ganó 2 líneas de visión y un (8%) paciente ganó 3 líneas de visión. El resto (42%) permaneció sin cambios comparados a la AVMC preoperatoria. Se encontraron diferencias estadísticamente significativas entre la AVSC preoperatoria (1.12 [±0.3]) y la AVSC postoperatoria (0.27 [±0.1]) (p=0.002, Z-Wilcoxon) y entre la AVMC postoperatoria (0.23 [±0.12]) y la AVMC preoperatoria (0.31 [±0.1]) (p=0.014, Z-Wilcoxon). No hubo complicaciones relacionadas con la cirugía.ConclusionesLa cirugía refractiva monocular en pacientes con ambliopía por anisometropía es una opción terapéutica segura y efectiva que ofrece resultados visuales satisfactorios, preservando o incluso mejorando la AVMC preoperatoria.AbstractPurposeTo investigate the efficacy and safety of LASIK for the correction of anisometropic amblyopia in adult patients.MethodsA retrospective, case series. We found 12 amblyopic adult patients that underwent monocular LASIK for anisometropía in our Cornea and Refractive service. We evaluated the preoperative and postoperative refractive error, spherical equivalent (SE), uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA). Snellen visual acuity measurements were converted to LogMAR for statistical purposes.ResultsThe mean age was 31.92 (±12.13) years. The average preoperative SE in the treated eyes was -3.49 (±3.24), the average SE of the untreated eye was 0.25(±0.30). Preoperative UCVA was 1.12 (±0.3) and average preoperative BCVA was 0.31 (±0.1). All patients had LASIK with an average follow-up time of 19.1(6-74) months. The average postoperative SE decreased to -0.28 (±0.48). Five patients (42%) gained 1 line of vision, 1 (8%) patient gained 2 lines of vision, 1 (8%) patient gained 3 lines of vision and the rest (42%) remained unchanged compared to preoperative BCVA. Statistically significant differences were observed between the preoperative UCVA [1.12 (±0.3)] with the postoperative UCVA [0.27 (±0.1)](p=0.002, Z-Wilcoxon) and between the postoperative BCVA [0.23 (±0.12)] with the preoperative BCVA [0.31 (±0.1)] (p=0.014, Z-Wilcoxon). There were no complications related to the surgical procedures.ConclusionsMonocular refractive surgery in adult patients with anisometropic amblyopia is a safe and effective therapeutic option that offers a satisfactory visual outcome, preserving or even improving the preoperative BCVA

Heavy metals as an indicator of ecological impact of a fragmented land uses, San Luis Potosi, Mexico

La necesidad de estudiar la presencia de metales pesados en el suelo radica en su impacto como indicador de contaminación ambiental. Se determinó la presencia de Cu, Zn, Pb y Cd en suelos donde se distribuyen especies vegetales en un corredor ecológico. Entre los municipios de Soledad de Graciano Sánchez y San Luis Potosí (México) fueron establecidos 30 puntos distribuidos en cinco prácticas dominantes de usos de suelo: agropecuario, residencial rural, comercio y servicios, residencial urbano y minero. Los muestreos se realizaron en cuatro épocas durante 2009 y 2010 (verano, otoño, invierno y primavera). Se encontró un efecto significativo del uso del suelo en cuanto a los niveles de Cu (p = 0,000), Pb (p = 0,043) y Cd (p = 0,010). En el caso del Zn, el uso del suelo (p = 0,000) y la estación (p = 0,059) fueron significativos. El uso del suelo minero mostró las mayores concentraciones de metales y el agrícola las menores. Los niveles de los cuatro metales se encuentran en el rango marcado como alto por la EPA y por otras fuentes técnicas. En el caso de Pb y Cd no rebasan los estándares NOM-147- SEMARNAT-SSA1. Estos resultados reflejan el potencial indicativo del uso del suelo en la evaluación de la calidad ambiental, sin embargo, se requiere continuar con un monitoreo de metales pesados en la zona.The need to study the presence of heavy metals in the soil lies on their impact as a indicator of environmental pollution. Therefore, it was determined the presence of Cu, Zn, Pb and Cd in soils where plant species were distributed in an ecological corridor. Among the municipalities of Soledad Graciano Sanchez and San Luis Potosi (Mexico), 30 points were established, distributed in five land uses: agricultural , rural residential, trade and services, urban residential and mining. Sampling was conducted from 2009 to 2010 (summer, fall, winter and spring). A significant effect of land use was found in terms of Cu (p = 0.000), Pb (p = 0.043) and Cd (p = 0.010). In the case of Zn both the land use (p = 0.000) and season (p = 0.059) had significant effects. It is emphasized that mining land use presented the highest concentrations of the studied metals and agricultural land use the lowest. The levels of four metals are in the range marked like high by the EPA and other technical sources. The levels of Pb and Cd do not exceed the NOM-147-SEMARNAT-SSA1. These results reflect the indicative potential of the soil and its consideration for future to evaluate the habitat of plant species. These results reflect the potential indicative land use in the assessment of environmental quality, however, requires continued monitoring of heavy metals in the area.Fil: Alcalá Jáuregui, Jorge. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: Ávila Castorena, Cecilia. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: Rodríguez Ortíz, Juan C.. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: Hernández Montoya, Alejandra. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: Beltrán Morales, F. Alfredo. Universidad Autónoma de Baja California Sur (México)Fil: Rodríguez Fuentes, Humberto. Universidad Autónoma de Nuevo León (México). Facultad de Agronomía.Fil: Loya Ramírez, J. Guadalupe. Universidad Autónoma de Baja California Sur (México

The ubiquitous ζ\zeta-function and some of its "usual" and "unusual" meromorphic properties

In this contribution we announce a complete classification and new exotic phenomena of the meromorphic structure of \z-functions associated to conic manifolds proved in \cite{KLP1}. In particular, we show that the meromorphic extensions of these \z-functions have, in general, countably many logarithmic branch cuts on the nonpositive real axis and unusual locations of poles with arbitrarily large multiplicity. Moreover, we give a precise algebraic-combinatorial formula to compute the coefficients of the leading order terms of the singularities.Comment: Paper presented at the 8th Workshop on Quantum Field Theory under the Influence of External Conditions (Leipzig, Germany, 16-21 September, 2007