This study simulates the gravity-driven drainage of an open spheroidal tank. A dimensionless parameter λ is introduced that alters the geometry of the tank but not its volume, generating prolate, spherical, and oblate spheroidal variants. The openings in the tank are obtained by cutting its surface with two symmetrical planes, close to the ends, without significantly affecting its capacity. Based on the principles of hydrodynamics, two models are developed: a general numerical model and an approximate analytical model based on Torricelli’s theorem for analyzing the drainage process as a function of geometry and time. Both models are implemented using Python 3.13 code. The results show excellent agreement between the two approaches for a specific range of λ, although the analytical model loses validity near a critical threshold. Under conditions of equal volume and discharge opening, the prolate tank drains faster despite a higher initial fluid level, while the oblate tank, with a lower initial height, drains more slowly. These results may be of particular interest in hydraulic and process engineering for the control of liquid storage and distribution. The implementation in Python 3.13 provides an open-access, fully reproducible, and classroom-applicable educational resource.
In the present study, we tested three procedures for [177Lu]Lu-DOTATATE activity to estimate the renal absorbed dose. Two of these procedures involved determining total kidney activity based on a single slice of the volume obtained by SPECT, with mass determined either through segmentation of a single Computed Tomography scan (CT, method 3) or from emission images (method 2). Both methods were compared against total activity quantification using a voxelby-voxel approach and SPECT-CT fusion images (method 1, taken as the reference). As a result of the analysis of post-administration studies from 6 patients, the following average values were obtained for mass: 425.5 +/- 33.62 g; 429.67 +/- 40.66 g; 433.33 +/- 34 g, accumulated activity 15013.67 +/- 5987.55 MBq-hs.; 15921.5 +/- 6205.3 MBq-hs.; 14996 +/- 5859.87 MBq-hs., and renal absorbed dose: 3.12 +/- 1.19 Gy; 3.14 +/- 1.23 Gy; 3.05 +/- 1.05 Gy for methods 3, 2, and 1, respectively. Although the number of patients analyzed is small, this work provides evidence that simplified methods for quantifying renal [177Lu]Lu-DOTATATE activity (Methods 2 and 3) yielded values like the voxelized SPECT-CT reference method and could be used in SPECT or hybrid SPECT-CT systems with low-dose CT.
We present the results of a study of the precise spatial orientation of 44 colonial churches and chapels located in the Biosphere Reserve of Gran Canaria (Spain). We analyze whether these orientations respond to calendrical coincidences related to patron saint festivities or to topographical features in the landscape, or whether they follow the ancient tradition of pointing churches’ apses eastward. Our results show that 40% of these buildings orient their axes within the solar range and, among these, a significant proportion of churches point their axes toward solstitial declinations, especially toward the northern hemisphere summer solstice. This result marks a difference with respect to the orientation patterns already studied on the other main islands of the Canary archipelago and could suggest the existence of a pattern imitating pre-Hispanic aboriginal worship.
En el presente trabajo pusimos a prueba dos procedimientos simplificados de cuantificación de la actividad de 177Lu-Dotatate para estimar la dosis absorbida renal. Estos consistieron en determinar la actividad total de los riñones a partir de un solo corte del volumen obtenido por SPECT y de la masa a partir de la segmentación de una sola tomografía computada o con las imágenes de emisión. Ambos métodos se compararon con la cuantificación de la actividad total mediante vóxel a vóxel e imágenes de fusión SPECT-CT. Cómo resultado del análisis de los estudios post administración de 6 pacientes constatamos que ambos métodos simplificados de cuantificación arrojaron, en promedio, valores aproximadamente similares de la masa, actividad acumulada y dosis absorbida renal. Mientras que la diferencia con respecto al método vóxel a vóxel fue como máximo un 13 % para la dosis absorbida. Aunque el número de pacientes analizados es bajo, este trabajo presentó evidencia que los métodos simplificados de cuantificación de la actividad renal de 177Lu-Dotatate podrían utilizarse en equipos SPECT o SPECT-CT híbridos con TC de baja dosis.
En este trabajo se simula el vaciado por gravedad de un tanque esferoidal abierto. Se introduce un parámetro adimensional λ que altera la geometría del tanque, pero no su volumen, generando variantes esferoidales prolata, esférica y oblata. Las aberturas del tanque resultan de cortar su superficie con dos planos simétricos, próximos a los extremos, sin afectar significativamente su capacidad. A partir de los principios de la hidrodinámica, se desarrollan dos modelos: uno numérico general y otro analítico aproximado basado en el teorema de Torricelli para el análisis del proceso de vaciado en función de la geometría y el tiempo. Ambos modelos se implementan mediante un código en Python 3.13. Los resultados muestran una excelente concordancia entre ambos enfoques para un rango específico de λ, aunque el modelo analítico pierde validez cerca de un umbral crítico. Bajo condiciones de igualdad entre volumen y abertura de descarga, el tanque prolato se vacía más rápido a pesar de un mayor nivel inicial de fluido, mientras que el oblato, con menor altura inicial, presenta un vaciado más lento. Estos resultados pueden ser de particular interés en ingeniería hidráulica y de procesos para el control de almacenamiento y distribución de líquidos. La implementación en Python 3.13 ofrece un recurso didáctico de libre acceso, completamente reproducible y aplicable en un aula.
Presentamos los resultados del estudio de la orientación espacial precisa de 44 iglesias y ermitas coloniales ubicadas en la Reserva de la Biosfera de la isla de Gran Canaria (España). Analizamos si las orientaciones responden a coincidencias calendáricas de fiestas patronales o a características topográficas del paisaje, o si se sigue la antigua tradición de apuntar los ábsides de las iglesias hacia oriente. Nuestros resultados muestran que el 40% de estas construcciones orientan sus ejes dentro del rango solar y, entre estas, que existe una notable proporción de templos que apuntan sus ejes hacia declinaciones solsticiales, especialmente hacia el solsticio de verano boreal. Este resultado marca una diferencia con los patrones de orientación ya estudiados en las otras islas principales del archipiélago canario y podría sugerir la existencia de un patrón de imitación del culto aborigen prehispánico.
The aim of this work is the validation of a computational code developed in Open FOAM, which will subsequently be used to simulate the behavior of the prototype employed for Cherenkov radiation detection, located in the Puna Saltena. The need to compare experimental data with numerical results obtained from the computational code motivated the performance of laboratory-scale experiments. The experimental approach consisted of heating water contained in a cylindrical vessel through its lateral walls until a quasi-steady state was reached, and determining the time interval in which the numerical results remain within acceptable relative error margins. Additional experiments involved heating through a constant heat flux applied to the lateral wall, followed by cooling due to ambient temperature. Temperature measurements were recorded during the tests inside the fluid and on the wall of the enclosure. The system configuration consists of a cylindrical glass vessel surrounded by a heater on the side wall, with the top and bottom surfaces thermally insulated. The Rayleigh number range studied is 9.26 & times; 10(6)-2.32 & times; 10(7), Prandtl's 4.31-7.37 and the aspect ratio (Height/Radius) of 2.31-2.58. The simulation was carried out using the Buoyant Pimple Foam transient solver of Open FOAM v.9, in two dimensions. Three mesh sizes were considered: 30 and 80, 50 and 130, 70 and 180, radial and axial splits, respectively; confirming that the second mesh is capable of generating acceptable results. In addition, the measured data of temperature inside the fluid and the simulated data were compared. The absolute and root mean square errors determined do not exceed 0,5 degrees C. Thus, the simulation results obtained under the conditions analyzed are in good agreement with the experimental data for the different test cases, allowing the computational tool to be adjusted for the thermal of tanks under real conditions.
The possibility of quantifying the activity of a radiopharmaceutical from SPECT images depends, among others, on the technical specifications of the imaging equipment, the isotope/collimator combination, and the presence of physical phenomena experienced by the emitted radiation that degrades the image. These factors can be investigated and optimized using Monte Carlo-based simulations. The aim of this work is to evaluate the accuracy on the quantification of I-131 activity from SPECT images obtained with a General Electric SPECT equipment, model Discovery NM 630, under different operational conditions. To this end, a gamma camera was configured in SIMIND MC as a computational model of the clinical equipment and lesions containing I-131 in different locations of an anthropomorphic phantom was configured as a model of the patient. Simulated SPECT images were obtained using general purpose medium-and highenergy collimators and different thicknesses of scintillation crystal, and I-131 activity was quantified from the images, with and without attenuation correction. The quantified I-131 activity from simulated SPECT images without attenuation correction is always smaller than the activity configured in the simulation, yielding errors of between 39 and 64%. The error in the quantification of I-131 activity markedly decreases when the image is corrected for attenuation, yielding error values less than 0.4% in the thyroid remnants. The work verified that it is possible to quantify I-131 activity from SPECT images if an attenuation correction method is available.
The original bunker was designed for a 6 MV linear accelerator; however, the replacement of a new 10 MV accelerator involved the relocation of the isocenter, which invalidated the existing shielding calculation. Therefore, a time-optimized constructive redesign was required to comply with Radiological Protection standards, including the evaluation of materials and geometries of hollowed blocks, by means of Monte Carlo simulations in EGSncr software, for 10 MV spectrum. The shielding calculation was performed according to the methodology of NCRP report No151, taking into account the existing thicknesses of the primary and secondary barriers, projected at a workload of 16 hours per day and dose rate of 2400 UM/min (10 MV FFF). The redesign of the facility included the width of the primary barriers of 20 cm in the direction of isocenter displacement, as well as the addition of 1 HVL in the secondary barriers abutting the medical physics office and the command room. Among the materials studied, it was chosen to use hollowed serpentine concrete blocks with NBS 04 concrete infill, reinforced with iron rods. In conclusion, the optimization of the bunker design for the 10 MV equipment complies with the national radiological protection standards, which was corroborated by the radiometric survey, thus ensuring the safety of personnel and patients.
The optimization of dose in Computed Tomography is a topic of ongoing research, including the search for objective image-quality metrics, especially in the clinical setting. This study evaluated the ability of new image-quality metrics to discriminate between Low-Dose and Diagnostic chest CT protocols in the same patients. Thirty clinical examinations corresponding to 15 patients were analyzed (one study per protocol for each patient). The metrics considered were the clinical contrast-to-noise ratio (CNRc) and its mean value (CNRca), as well as the clinical spatial resolution expressed as the full width at half maximum (FWHMc) and its mean value per image (FWHMca), estimated from the edge-spread function of relevant anatomical structures. Size-specific dose estimates (SSDE) were 8.8 ± 1.5 mGy for the Low-Dose protocol and 13.5 ± 2.9 mGy for the Diagnostic protocol. CNRc and FWHMca exhibited statistically significant differences between protocols: FWHMca ranged from 1.40–1.97 mm in Low-Dose scans versus 0.9–1.2 mm in Diagnostic scans. These results confirm that CNRc, FWHMc and, in particular, FWHMca can quantitatively characterize clinical image quality, although larger-scale studies are needed to consolidate these observations.
In the last 20 years, the use of CMOS cameras has experienced a strong growth, accompanied by significant improvements in their performance. In this work, we carry out an exhaustive characterization of this technology using commercial sensors. We present the measurement of the photon transfer curve, which allows us to evaluate the dynamic range and linearity of the sensor. We measure the dark current rate as a function of temperature and analyze the effect of the infrared filter. In addition, we determine the readout noise, obtaining an average value of (3.06 +/- 0.01) e-. The results presented on the operating limits and potential scientific applications of commercial CMOS sensors are intended to serve as a starting point for a series of undergraduate-level experiments, as well as for their use in a variety of scientific applications.
In this work, we aim to functionalize the surface of a perovskite oxide (ABO(3) structure) with Ni-Fe nanoparticles via the exsolution technique, with the goal of enhancing its electrocatalytic properties as an electrode for solid oxide cells (SOC). Exsolution is a surface-decoration technique based on the controlled segregation of elements originally contained within the host oxide (in our case, Sr(Ti0.3Fe0.7)O-3-(delta), referred to as STF). We show how the exsolution of B-site metal cations leads to an excess of Sr at the A-site of the perovskite, which impacts negatively on its electrochemical performance. As a strategy to counteract this effect, we explore the introduction of a Sr deficiency at the A-site of the starting perovskite. Finally, we compare the fabrication of Ni-doped, Sr-deficient STF electrodes (composition Sr0.93Ti0.3Fe0.63Ni0.07O3-delta) using two different synthesis routes: the solid-state reaction method and a sol-gel route.
In the present work, a fluorescence microscopy system was implemented that allows the acquisition of three dimensional images for subsequent processing using the SUPPOSe 3D algorithm with the aim of obtaining a superresolution reconstruction. SUPPOSe is a superresolution deconvolution algorithm that allows reconstructing the true distorted structure in an image by incorporating a priori information. The SUPPOSe approach consists of approximating the real structure in the sample as a superposition of point sources of equal intensity, called virtual sources. This procedure simplifies the deconvolution problem and converts it into an unconstrained minimization problem, which must be solved by finding the positions of the virtual sources. These positions can take values in the whole domain and are determined by minimizing an objective function through a genetic algorithm. Throughout this work the SUPPOSe method was tested for both synthetically generated and experimentally acquired 3D images with the implemented system. Samples with known structures were used to validate the results obtained and to evaluate the performance of the algorithm as a function of the characteristics of the processed images.
The transfer of van der Waals materials is a fundamental step for their characterization and integration into devices, as it allows the study of their intrinsic properties without interference from the synthesis environment. In this paper, we present a polymer-free wet transfer technique that uses only water as the separation medium. This methodology enables the transfer of MoS2 crystals from their growth substrate onto arbitrary surfaces. Unlike other wet transfer methods, it allows the selective transfer of small regions of the material, making it possible to reuse the same growth substrate for multiple experiments. Optical microscopy and Raman spectroscopy confirm the preservation of both morphology and structural quality of the transferred material. The simplicity and versatility of the procedure make it an attractive alternative to conventional transfer techniques.
During their operation, due to shifts in environmental conditions, devices undergo various forms of detuning from their optimal settings. Typically, this is addressed through control loops, which monitor variables and the device performance, to maintain settings at their optimal values. Quantum devices are particularly challenging since their functionality relies on precisely tuning their parameters. At the same time, the detailed modeling of the environmental behavior is often computationally unaffordable, while a direct measure of the parameters defining the system state is costly and introduces extra noise in the mechanism. In this study, we investigate the application of reinforcement learning techniques to develop a model-free control loop for continuous recalibration of quantum device parameters. Furthermore, we explore the advantages of incorporating minimal environmental noise models. As an example, the application to numerical simulations of a Kennedy receiver-based long-distance quantum communication protocol is presented.
En este trabajo se estudian algunas propiedades de las ondas rotantes progresivas (ORP) en un tubo infinito con simetría helicoidal, como consecuencia de la propiedad dinámica de los flujos de Beltrami1,5,6 (PDFB, González, 2014, 2022, 2023). Se muestra que la clasificación de ondas no interactuantes depende de sus velocidades de fase de la forma donde es el signo de la helicidad, lo que implica una velocidad de fase diferente para cada o sea una separación de modos con diferentes números azimutales. Que esto da lugar a un método geométrico para encontrar las ondas no interactuantes en función de su velocidad de fase. Y que esta clasificación facilita el estudio de propiedades de estas ondas como por ejemplo el transporte de momento angular que se calcula como ejemplo para un caso particular.
Cerca del 95 % de los incendios forestales ocurren por causas antropogénicas. La quema de pastizales como método de barrido para la explotación ganadera y agrícola ha sido implementada desde hace más de dos siglos en el continente americano. Cada invierno, el fuego es utilizado para el rebrote de especies forrajeras en el Delta del río Paraná. Las condiciones meteorológicas atípicas y el cambio climático han exacerbado el impacto de los incendios alrededor del mundo. En el año 2020, la acumulación y propagación de las emisiones de incendios forestales sin precedentes afectaron a los habitantes del Área Metropolitana de Rosario (AMR), Argentina. En este trabajo, se analizaron las condiciones meteorológicas, el número de focos de incendios detectados por el instrumento satelital VIIRS y la concentración del material particulado fino (PM2.5) medida en el AMR. Se calcularon las anomalías de la precipitación, humedad relativa y temperatura registradas in situ entre junio y agosto en el periodo 2010-2020. Los resultados muestran que para el año 2020, la humedad y temperatura ambientes tuvieron una disminución en promedio del 10 % y 3 %, respectivamente, mientras que la precipitación acumulada tuvo una reducción alrededor del 70 %, con respecto a los años anteriores. El modelo de agrupamiento mostró que la mediana más alta del NI coincide con la menor precipitación acumulada y baja humedad relativa, así como vientos predominantes del sector noroeste. El análisis de vientos revela que las corrientes provenientes de la dirección noroeste promovieron una mayor afectación superficial de los incendios en el Delta del río Paraná y los vientos del noreste incrementaron los niveles de PM2.5 en el AMR. Estos hallazgos subrayan la importancia de considerar las condiciones meteorológicas en la evaluación de riesgos ambientales y en la formulación de estrategias de mitigación frente a la contaminación del aire y los incendios forestales.
En este trabajo se describe el desarrollo de una GUI (Graphic User Interface) en Python para sistematizar el análisis de imágenes, en el marco del estudio hemorreológico in vitro de fitoquímicos que podrían ser utilizados en el tratamiento de la diabetes. Los criterios de usabilidad de la GUI basada en la librería TkInter están dirigidos a usuarios no expertos. Los algoritmos de procesamiento de imágenes están contenidos en la biblioteca OpenCV2, que utiliza las redes neuronales previamente entrenadas. Las imágenes se obtuvieron con una cámara digital acoplada a un microscopio invertido y objetivo 40x. En este trabajo se optimizó el proceso de búsqueda de parámetros (porcentajes de células aisladas y el coeficiente de células aisladas) para glóbulos rojos incubados con soluciones de quercetina a distintas concentraciones. Palabras clave: interfaz gráfica de usuario, python, quercetina, diabetes.
En este trabajo se utilizó un enfoque experimental para evaluar la utilidad de la técnica de biospeckle en el estudio del proceso de coagulación sanguínea. Se analizaron los tiempos de tromboplastina parcial con activador en plasma normal, plasma con deficiencia de Factor VIII y la mezcla de ambos. Los resultados muestran una correlación entre los cambios en los patrones de speckle y la formación de la malla de fibrina en las muestras normal y patológica. En consecuencia, la técnica de biospeckle puede ser una herramienta útil para evaluar la hemostasia y los cambios que se generan en la polimerización de la fibrina frente a deficiencias o interferencias. Palabras Clave: biospeckle, coagulación sanguínea, THSP, coeficiente de correlación, procesamiento de señales.
El desarrollo de dispositivos microfluídicos se presenta como un enfoque innovador para mejorar las técnicas actuales de reproducción asistida las cuales distan de ser muy eficientes. El diseño de estos microdispositivos en general es muy chato, posee muchos canales y todas las paredes desempeñan un papel fundamental, encontrándose a distancias micrométricas entre ellas. Para estudiar este efecto de alto confinamiento, se modeló el movimiento espermático humano en dos dimensiones utilizando dinámica de Langevin. Se calcularon los perfiles de densidad celular dentro de canales (con entradas y salidas asimétricas) de ancho micrométrico y aspecto (ancho/largo, w/L) menor a uno. Con el propósito de obtener una representación precisa de su dinámica oscilatoria, se utilizó un modelo fenomenológico con parámetros de movilidad espermática obtenidos experimentalmente. Al disminuir el ancho del canal, se observa que la cercanía entre las paredes influye significativamente en la distribución de densidad principalmente cuando la distancia entre ellas es de pocas células, haciendo evidente los efectos de alto confinamiento. Se observó que el perfil transversal varía para distintas posiciones a lo largo del canal, especialmente cerca a las entradas y salidas, y se mantiene constante en torno a la mitad del largo (L/2). Por ejemplo, para un largo de 300 μm el perfil se mantiene constante a lo largo de 125 μm, en cambio para canales muy cortos como L=50μm los perfiles son distintos a lo largo del canal, es decir, la asimetría del mismo domina.
