Comparative study of two laparoscopic instrument tracker designs for motion analysis and image-guided surgery: a technical evaluation

Laparoscopic instrument tracking systems are a key element in image-guided interventions, which requires high accuracy to be used in a real surgical scenario. In addition, these systems are a suitable option for objective assessment of laparoscopic technical skills based on instrument motion analysis. This study presents a new approach that improves the accuracy of a previously presented system, which applies an optical pose tracking system to laparoscopic practice. A design enhancement of the artificial markers placed on the laparoscopic instrument as well as an improvement of the calibration process are presented as a means to achieve more accurate results. A technical evaluation has been performed in order to compare the accuracy between the previous design and the new approach. Results show a remarkable improvement in the fluctuation error throughout the measurement platform. Moreover, the accumulated distance error and the inclination error have been improved. The tilt range covered by the system is the same for both approaches, from 90º to 7.5º. The relative position error is better for the new approach mainly at close distances to the camera syste

Optical properties from extinction cross-section of single pollen particles under laboratory-controlled relative humidity

This work was supported by the Spanish Ministry of Science and Innovation through projects ELPIS (PID2020-12001-5RB-I00), by the Junta de Andalucía Excellence project ADAPNE (P20-00136), AEROPRE (P-18-RT-3820), FEDER Una manera de hacer Europa, EQC2019-006423-P, INTEGRATYON (PID2020-117825 GB-C21 and PID2020-117825 GB-C22), the European Union's Horizon 2020 research and innovation program through project ACTRIS. IMP (grant agreement No 871115), and ATMO-ACCESS (grant agreement No 101008004), and ACTRIS-España (RED2022-134824-E), FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades project DEM3TRIOS (A-RNM-430-UGR20) and by University of Granada Plan Propio through Excellence Research Unit Earth Science and Singular Laboratory AGORA (LS2022-1) programs and project Pre-GREENMITIGATION (PP2022.PP.34).A growing body of research suggests that pollen suspended in the atmosphere have a major environmental and climatic impact. However, our current knowledge of pollen is rather limited with respect to its extinction capacity, its optical properties and how these vary with atmospheric water content. Understanding their water absorption capacity can improve our understanding of their radiative effects and, thus, improve climate models. In this work, an electrodynamic Paul trap was coupled to a cavity ring down spectroscopy (CRDS) to directly measure the ring down time () of four individual types of pollen particles: Olea, Fraxinus, Populus and Salix exposed to changing relative humidity (RH). Resonant structures in values between ∼90 and 45 % RH indicated that pollen was wettable at high RHs. was used to calculate light extinction cross-section at 532 nm as a function of RH. Optical growth factor () was evaluated as the ratio between and From , the semi-empirical single hygroscopicity parameter () was found to be 0.038–0.058 for the four pollen types. Under controllable treatment of the water content and an adequate selection of complex refractive index , CRDS- data was fitted to theoretical from Mie theory. The reasonable agreement achieved allowed for gaining knowledge about the and how particle size shrugged during dehydration. As a result, a climate-lowering effect of Olea pollen particles, which contain a fraction of scattered aerosol, should be considered in the models.Spanish Ministry of Science and Innovation (PID2020-12001-5RB-I00)Junta de Andalucía Excellence: ADAPNE (P20-00136), AEROPRE (P-18-RT-3820), FEDER Una manera de hacer Europa, EQC2019-006423-P, INTEGRATYON (PID2020-117825GB-C21, PID2020-117825GB-C22)European Union's Horizon 2020 CTRIS.IMP 871115ATMO-ACCESS 101008004ACTRIS-España (RED2022-134824-E)FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades DEM3TRIOS (A-NM-430-UGR20)University of Granada LS2022-1, PP2022.PP.3

Production of drug-releasing biodegradable microporous scaffold impregnated with gemcitabine using a CO2 foaming process

The use of supercritical fluids technology, in particular the use of CO2, is an important advantage over other production techniques of controlled release systems. The impregnation and foaming process can be carried out in a single step. By adjusting the conditions of pressure, temperature, depressurization time or type of polymer used, microcellular scaffolds can be obtained with desired characteristics and adapted to the patient's requirements. Moreover, it has been demonstrated that the use of polymeric solutions allows carrying out impregnation process at mild conditions. In this work, Gemcitabine impregnation in PLGA foams from polymeric solutions of ethyl lactate has been studied. The effect of polymer lactide to glycolide ratio (50:50 or 75:25), pressure (120 or 200 bar) and temperature (25 or 40 °C) were studied for three initial drug ratios (175, 105 or 35 mg GEM/g PLGA). Cell size of the foams varied between 35 μm and 158 μm, achieving an impregnation efficiency higher than 90 %. Finally, a study of the release profile of Gemcitabine in Phosphate Buffered Saline (PBS) was investigated and a mathematical modelling was carried out. In this model it was considered that the release process was divided into three different steps controlled by the external diffusion in the first place, by the internal transfer of mass in the second and then by the degradation of the polymer.El uso de la tecnología de fluidos supercríticos, en particular el uso de CO2, es una importante ventaja frente a otras técnicas de producción de sistemas de liberación controlada. El proceso de impregnación y espumado se puede realizar en un solo paso. Ajustando las condiciones de presión, temperatura, tiempo de despresurización o tipo de polímero utilizado, se pueden obtener andamios microcelulares con las características deseadas y adaptados a los requerimientos del paciente. Además, se ha demostrado que el uso de soluciones poliméricas permite llevar a cabo el proceso de impregnación en condiciones suaves. En este trabajo se ha estudiado la impregnación de gemcitabina en espumas de PLGA a partir de soluciones poliméricas de lactato de etilo. El efecto de la relación entre la lactida y el glicólido del polímero (50:50 o 75:25), Se estudiaron la presión (120 o 200 bar) y la temperatura (25 o 40 °C) para tres proporciones iniciales de fármaco (175, 105 o 35 mg GEM/g PLGA). El tamaño de celda de las espumas varió entre 35 μm y 158 μm, logrando una eficiencia de impregnación superior al 90 %. Finalmente, se investigó un estudio del perfil de liberación de gemcitabina en solución salina tamponada con fosfato (PBS) y se llevó a cabo un modelo matemático. En este modelo se consideró que el proceso de liberación se dividía en tres pasos diferentes controlados por la difusión externa en primer lugar, por la transferencia interna de masa en el segundo y luego por la degradación del polímero. Se investigó un estudio del perfil de liberación de gemcitabina en solución salina tamponada con fosfato (PBS) y se llevó a cabo un modelo matemático. En este modelo se consideró que el proceso de liberación se dividía en tres pasos diferentes controlados por la difusión externa en primer lugar, por la transferencia interna de masa en el segundo y luego por la degradación del polímero. Se investigó un estudio del perfil de liberación de gemcitabina en solución salina tamponada con fosfato (PBS) y se llevó a cabo un modelo matemático. En este modelo se consideró que el proceso de liberación se dividía en tres pasos diferentes controlados por la difusión externa en primer lugar, por la transferencia interna de masa en el segundo y luego por la degradación del polímero

Technical evaluation of a third generation optical pose tracker for motion analysis and image-guided surgery

Laparoscopic instrument tracking systems are an essential component in image-guided interventions and offer new possibilities to improve and automate objective assessment methods of surgical skills. In this study we present our system design to apply a third generation optical pose tracker (Micron- Tracker®) to laparoscopic practice. A technical evaluation of this design is performed in order to analyze its accuracy in computing the laparoscopic instrument tip position. Results show a stable fluctuation error over the entire analyzed workspace. The relative position errors are 1.776±1.675 mm, 1.817±1.762 mm, 1.854±1.740 mm, 2.455±2.164 mm, 2.545±2.496 mm, 2.764±2.342 mm, 2.512±2.493 mm for distances of 50, 100, 150, 200, 250, 300, and 350 mm, respectively. The accumulated distance error increases with the measured distance. The instrument inclination covered by the system is high, from 90 to 7.5 degrees. The system reports a low positional accuracy for the instrument tip

Production of biodegradable PLGA foams processed with high pressure CO2

Microcellular scaffolds were prepared using high pressure fluids. Solutions of biodegradable material Poly (lactic-co-glycolic) acid (PLGA) in a green solvent such as ethyl lactate was used as the scaffold matrix. To carry out polymer foaming from polymer solutions allows the possibility of reducing the working temperature. The effect of the ratio lactide to glycolide of the polymer, the working pressure, the initial concentration of the polymer in the solvent and the depressurization time were the variables studied at a temperature of 25 °C. The morphology of the foams obtained was characterized based on the cell diameter and its standard deviation, indicator of the homogeneity of the scaffolds obtained, as well as the density of cells. In addition, a study was performed on how the glass transition temperature (Tg) of a polymer is modified by the plasticizing effect of CO2 pressure.Los andamios microcelulares se prepararon utilizando fluidos a alta presión. Como matriz de andamiaje se utilizaron soluciones de material biodegradable ácido poli (láctico-co-glicólico) (PLGA) en un disolvente verde como el lactato de etilo. Llevar a cabo la espumación de polímeros a partir de soluciones de polímeros permite la posibilidad de reducir la temperatura de trabajo. El efecto de la relación láctido a glicólido del polímero, la presión de trabajo, la concentración inicial del polímero en el solvente y el tiempo de despresurización fueron las variables estudiadas a una temperatura de 25 °C. La morfología de las espumas obtenidas se caracterizó en base al diámetro de celda y su desviación estándar, indicador de la homogeneidad de los andamios obtenidos, así como la densidad de celdas. Además,2 presiones

Measurement, correlation and modelling of high-pressure phase equilibrium of PLGA solutions in CO2

Poly (lactic-co-glycolic acid) (PLGA) is a copolymer used as drug carrier in controlled release systems as microparticles or scaffolds. Foamed structures are industrially obtained by injecting gas at temperatures above the melting point of the polymer that may promote PLGA degradation. High temperatures are avoidable in this foaming process if a polymer dissolution is used. Ethyl acetate and ethyl lactate are suitable solvents for the PLGA since the polymer is easily solubilised, is environmentally friendly and highly recommendable for medical purposes. CO2 is proposed as antisolvent because is environmentally benign, non-flammable and non-toxic. The knowledge of the solubility of these solvents in CO2 is essential to find the most appropriate working conditions for the foaming process. In this work, the solubility of ethyl acetate and ethyl lactate in CO2 in the presence of different initial concentrations of PLGA has been studied at 298.15 K and at pressures up to 150 bar using a high-pressure variable volume view cell.El poli (ácido láctico-co-glicólico) (PLGA) es un copolímero que se utiliza como transportador de fármacos en sistemas de liberación controlada como micropartículas o andamios. Las estructuras espumadas se obtienen industrialmente mediante la inyección de gas a temperaturas superiores al punto de fusión del polímero que pueden promover la degradación del PLGA. Las altas temperaturas se pueden evitar en este proceso de formación de espuma si se utiliza una disolución de polímero. El acetato de etilo y el lactato de etilo son disolventes adecuados para el PLGA ya que el polímero se solubiliza fácilmente, es respetuoso con el medio ambiente y muy recomendable para fines médicos. El CO2 se propone como antidisolvente porque es ambientalmente benigno, no inflamable y no tóxico. El conocimiento de la solubilidad de estos disolventes en CO 2es fundamental encontrar las condiciones de trabajo más adecuadas para el proceso de espumado. En este trabajo se ha estudiado la solubilidad del acetato de etilo y lactato de etilo en CO 2 en presencia de diferentes concentraciones iniciales de PLGA a 298,15 K y presiones de hasta 150 bar utilizando una celda de visión de volumen variable de alta presión

Copper wire as a clean and efficient catalyst for click chemistry in supercritical CO2

Use of copper wire bits as simple catalyst in a click chemistry reaction using supercritical CO2 has been achieved. The use of this catalyst in the reaction between polylactic acid (PLA) and coumarin allows to remove the whole amount of catalyst in the final product with a simple purification step using a green solvent where no toxic solvent is used in order to synthetize the product.Se ha logrado el uso de brocas de alambre de cobre como catalizador simple en una reacción química clic usando CO2 supercrítico . El uso de este catalizador en la reacción entre el ácido poliláctico (PLA) y la cumarina permite eliminar la cantidad total de catalizador en el producto final con un simple paso de purificación usando un solvente verde donde no se usa ningún solvente tóxico para sintetizar el producto

Automating Customer Experience Agents’ Evaluation with Natural Language Processing

The importance and relevance of online commerce in society have grown uninterruptedly over the last years, with people changing their purchasing habits. The COVID-19 pandemic significantly accelerated this adoption, as quarantines forced people to stay in their homes. Under this scenario, online shopping became a more convenient option, considering product availability, the possibility to compare prices and shipping options, and door-to-door delivery. With this, e-commerce retailers and marketplaces must give excellent customer service to their customers, especially in this context when most activities are returning to their pre-COVID levels and restrictions. To manage customers that have any kind of problem, digital marketplaces and retailers usually have a team of Customer Experience (CX) agents that interact, talk and answer clients’ questions and inquiries, avoiding any potential negative situations on three different channels: voice calls, e-mails, and chat messages.Sociedad Argentina de Informática e Investigación Operativ

Analytic-numerical solution of random boundary value heat problems in a semi-infinite bar

[EN] This paper deals with the analytic-numerical solution of random heat problems for the temperature distribution in a semi-infinite bar with different boundary value conditions. We apply a random Fourier sine and cosine transform mean square approach. Random operational mean square calculus is developed for the introduced transforms. Using previous results about random ordinary differential equations, a closed form solution stochastic process is firstly obtained. Then, expectation and variance are computed. Illustrative numerical examples are included.This work has been partially supported by the Ministerio de Economia y Competitividad Grant no. DPI2010-20891-C02-01 and Universitat Politecnica de Valencia Grant no. PAID06-11-2070.Casabán Bartual, MC.; Cortés López, JC.; García Mora, MB.; Jódar Sánchez, LA. (2013). Analytic-numerical solution of random boundary value heat problems in a semi-infinite bar. Abstract and Applied Analysis. 2013(676372):1-9. https://doi.org/10.1155/2013/676372S192013676372Chiba, R. (2009). Stochastic heat conduction analysis of a functionally graded annular disc with spatially random heat transfer coefficients. Applied Mathematical Modelling, 33(1), 507-523. doi:10.1016/j.apm.2007.11.014Li, Y., & Long, S. (2009). A finite element model based on statistical two-scale analysis for equivalent heat transfer parameters of composite material with random grains. Applied Mathematical Modelling, 33(7), 3157-3165. doi:10.1016/j.apm.2008.10.018Cortés, J. C., Jódar, L., Villafuerte, L., & Villanueva, R. J. (2007). Computing mean square approximations of random diffusion models with source term. Mathematics and Computers in Simulation, 76(1-3), 44-48. doi:10.1016/j.matcom.2007.01.020Cortés, J.-C., Jódar, L., Roselló, M.-D., & Villafuerte, L. (2012). Solving initial and two-point boundary value linear random differential equations: A mean square approach. Applied Mathematics and Computation, 219(4), 2204-2211. doi:10.1016/j.amc.2012.08.066Madera, A. G. (1993). Modelling of stochastic heat transfer in a solid. Applied Mathematical Modelling, 17(12), 664-668. doi:10.1016/0307-904x(93)90077-tMadera, A. G., & Sotnikov, A. N. (1996). Method for analyzing stochastic heat transfer in a fluid flow. Applied Mathematical Modelling, 20(8), 588-592. doi:10.1016/0307-904x(96)00006-6Villafuerte, L., Braumann, C. A., Cortés, J.-C., & Jódar, L. (2010). Random differential operational calculus: Theory and applications. Computers & Mathematics with Applications, 59(1), 115-125. doi:10.1016/j.camwa.2009.08.061Calbo, G., Cortés, J.-C., & Jódar, L. (2011). Random Hermite differential equations: Mean square power series solutions and statistical properties. Applied Mathematics and Computation, 218(7), 3654-3666. doi:10.1016/j.amc.2011.09.008Cortés, J. C., Sevilla-Peris, P., & Jódar, L. (2005). Analytic-numerical approximating processes of diffusion equation with data uncertainty. Computers & Mathematics with Applications, 49(7-8), 1255-1266. doi:10.1016/j.camwa.2004.05.01

Improvement of PLGA loading and release of curcumin by supercritical technology

This work studies the feasibility of supercritical technology for the improvement of the loading and release of curcumin in PLGA. We synthetized the poly (lactic-co-glycolic acid (PLGA) support as a solid block, determining the effect of PLGA molar composition in the range (20:80 to 80:20). A curcumin solubility study selected acetone, methanol and ethanol like more convenient solvents. Curcumin impregnation process was studied at atmospheric and high pressure using scCO2. High-pressure impregnation performances practically doubled bulk results, leading to values up to 86.1% and practically free of solvent in a sponge form. These samples could be commercialized without any further purification step. The release kinetics of the samples constantly delivered more than 90% of curcumin between 9 and 12 days. Compared to other technologies our samples improved significantly the combined loading and release characteristics, indicating that supercritical technology is an interesting alternative for curcumin loading and controlled delivery in medical applications.Este trabajo estudia la viabilidad de la tecnología supercrítica para la mejora de la carga y liberación de curcumina en PLGA. Sintetizamos el soporte de poli (ácido láctico-co-glicólico (PLGA) como un bloque sólido, determinando el efecto de la composición molar de PLGA en el rango (20:80 a 80:20). Un estudio de solubilidad de la curcumina seleccionó acetona, metanol y etanol. como solventes más convenientes El proceso de impregnación de curcumina se estudió a presión atmosférica y alta usando scCO 2. Las prestaciones de impregnación a alta presión prácticamente duplicaron los resultados a granel, llegando a valores de hasta el 86,1% y prácticamente sin disolvente en forma de esponja. Estas muestras podrían comercializarse sin ningún otro paso de purificación. La cinética de liberación de las muestras entregó constantemente más del 90 % de curcumina entre 9 y 12 días. En comparación con otras tecnologías, nuestras muestras mejoraron significativamente las características combinadas de carga y liberación, lo que indica que la tecnología supercrítica es una alternativa interesante para la carga y el suministro controlado de curcumina en aplicaciones médicas