765 research outputs found

    Excitations and S-matrix for su(3) spin chain combining 3{3} and ${3^{*}}

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    The associated Hamiltonian for a su(3) spin chain combining 3{3} and 3{3^{*}} representations is calculated. The ansatz equations for this chain are obtained and solved in the thermodynamic limit, and the ground state and excitations are described. Thus, relations between the number of roots and the number of holes in each level have been found . The excited states are characterized by means of these quantum numbers. Finally, the exact S matrix for a state with two holes is found.Comment: 17 pages, plaintex, harvmac (to be published in J. of Phys. A

    Integrable su(3) spin chain combining different representations

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    The general expression for the local matrix t(θ)t(\theta) of a quantum chain with the site space in any representation of su(3) is obtained. This is made by generalizing t(θ)t(\theta) from the fundamental representation and imposing the fulfillment of the Yang-Baxter equation. Then, a non-homogeneous spin chain combining different representations of su(3) is solved by developing a method inspired in the nested Bethe ansatz. The solution for the eigenvalues of the trace of the monodromy matrix is given as two coupled Bethe equations. A conjecture about the solution of a chain with the site states in different representations of su(n) is presented. The thermodynamic limit of the ground state is calculated.Comment: PlainTex harvmac, 30 pages, 7 figures, to appear in Journal of Physics

    Artificial intelligence in wind speed forecasting: a review

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    Wind energy production has had accelerated growth in recent years, reaching an annual increase of 17% in 2021. Wind speed plays a crucial role in the stability required for power grid operation. However, wind intermittency makes accurate forecasting a complicated process. Implementing new technologies has allowed the development of hybrid models and techniques, improving wind speed forecasting accuracy. Additionally, statistical and artificial intelligence methods, especially artificial neural networks, have been applied to enhance the results. However, there is a concern about identifying the main factors influencing the forecasting process and providing a basis for estimation with artificial neural network models. This paper reviews and classifies the forecasting models used in recent years according to the input model type, the pre-processing and post-processing technique, the artificial neural network model, the prediction horizon, the steps ahead number, and the evaluation metric. The research results indicate that artificial neural network (ANN)-based models can provide accurate wind forecasting and essential information about the specific location of potential wind use for a power plant by understanding the future wind speed values

    Reutilización Fraccional de Frecuencia con Sectorización sobre Redes Celulares

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    In this paper, we investigate the downlink of homogeneous LTE cellular networks with Fractional Frequency Reuse (FFR) and sectorized antennas where non-ideal radiation patterns have been considered. Three frequency allocation schemes are proposed: i) static; ii) dynamic and iii) proportional, that differ in complexity and performance. Such schemes are compared in terms of aggregate (per cell) capacity and fairness for the case of 3 and 6 sectors. Results reveal that proportional allocation achieves a good balance between aggregate capacity and fairness, while dynamic allocation achieves the highest capacity with a small fairness. Finally, it is observed that 6-sectors configuration leads to a higher capacity and fairness.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Relación entre el valor del ratio elastográfico y la clasificación citológica de Bethesda en la patología tiroidea

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    ResumenObjetivoPresentar nuestra experiencia en la categorización de la patología tiroidea, a través de la utilización de parámetros ecográficos de malignidad y elastografía con medición del ratio de la deformación tisular, y la correlación de los hallazgos obtenidos con la clasificación citológica de Bethesda.Materiales y métodosSe llevó a cabo un estudio prospectivo y observacional, entre septiembre de 2012 y abril de 2013, que incluyó 137 nódulos tiroideos. Se excluyeron 10 casos Bethesda III-IV. Se realizó ecografía, power Doppler, visualización de micropartículas (Micropure) y elastografía con medición del ratio elastográfico, así como también punción aspirativa con aguja fina guiada por ecografía (con el citólogo presente), utilizando la clasificación Bethesda. Los estudios fueron hechos por el mismo operador con un ecógrafo Toshiba Aplio 400 y los datos estadísticos se evaluaron con el programa IBM SPSS Statistics 20.ResultadosSe estudiaron 127 nódulos en pacientes con una edad promedio de 59±16 años. El 82% de los casos ocurrió en mujeres. Ciento veinte nódulos (94%) fueron clasificados como Bethesda II. La media elastográfica para Bethesda I-II fue de 1,94±2,12 vs. 7,07±5,46 para V-VI (p: 0,048). El punto de corte elastográfico ≤ 2 (87 de 127) presentó una sensibilidad del 85,7% y una especificidad del 81,7% para predecir Bethesda asociada a patología benigna, con un valor predictivo negativo (VPN) del 99% y un valor predictivo positivo del 15%.ConclusionesEl ratio elastográfico permitió descartar la patología tiroidea maligna con valores ≤ 2 y un VPN del 99%, mejorando la selección de los pacientes a punzar. El incremento del ratio elastográfico se asoció a una mayor probabilidad de patología maligna, aunque no se pudo establecer un valor de corte debido al bajo número de casos con Bethesda V-VI.AbstractObjectivesWe present our experience in the categorization of thyroid pathology using the sonographic parameters of malignancy and elastography with measurement elastography strain ratio, to evaluate the relationship between the results found and the Bethesda classification.Materials and methodsProspective observational study, included 137 thyroid nodules studied between September 2012- April 2013. We excluded 10 cases with Bethesda categories III-IV. Ultrasonography, Doppler, Micropure, elastogrphy strain ratio between the lesion and the normal tissue, fine needle aspiration cytology (FNAC),were the diagnosis methods used. The pathologist was always present and the cytological classi fication of Bethesda was used. All study was made by the same physician used Toshiba Aplio 400 ultrasound unit. Results were analyzed with IBM SPSS Statistics 20.ResultsWe studied 127 nodules in patients 59±16 years old, 82% were female; 120 were Bethesda II (94%). The average strain ratio for nodules Bethesda I-II was 1.94±2.12 vs. 7.07±5.46 for those nodules Bethesda V-VI (p:0,048). This means that an elastography strain ratio ≤ 2 (87 of 127 nodules) has a sensibility of 85.7% and a specificity of 81.7% of predicting Bethesda associated with benign pathology with a negative predictive value (NPV) of 99% and a positive predictive value of 15%.ConclusionThe elastography strain ratio allowed to discard malignant nodules with strain ratio ≤ 2 with a NPV of 99% improves the selection of patients for FNAC. The increment in the elastography strain ratio was associated to a higher possibility of malignant thyroid pathology, being unable to determine a limit value due to the low amount of cases with nodules Bethesda V-VI

    Biorefinery of biomass of agro-Industrial banana waste to obtain high-value biopolymers

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    On a worldwide scale, food demand is increasing as a consequence of global population growth. This makes companies push their food supply chains’ limits with a consequent increase in generation of large amounts of untreated waste that are considered of no value to them. Biorefinery technologies offer a suitable alternative for obtaining high-value products by using unconventional raw materials, such as agro-industrial waste. Currently, most biorefineries aim to take advantage of specific residues (by either chemical, biotechnological, or physical treatments) provided by agro-industry in order to develop high-value products for either in-house use or for sale purposes. This article reviews the currently explored possibilities to apply biorefinery-known processes to banana agro-industrial waste in order to generate high-value products out of this residual biomass source. Firstly, the Central and Latin American context regarding biomass and banana residues is presented, followed by advantages of using banana residues as raw materials for the production of distinct biofuels, nanocellulose fibers, different bioplastics, and other high-value products Lastly, additional uses of banana biomass residues are presented, including energy generation and water treatmen

    Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron II. Observations of 3C 273 at minimum activity

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    RadioAstron is a 10 m orbiting radio telescope mounted on the Spektr-R satellite, launched in 2011, performing Space Very Long Baseline Interferometry (SVLBI) observations supported by a global ground array of radio telescopes. With an apogee of about 350 000 km, it is offering for the first time the possibility to perform {\mu}as-resolution imaging in the cm-band. We present observations at 22 GHz of 3C 273, performed in 2014, designed to reach a maximum baseline of approximately nine Earth diameters. Reaching an angular resolution of 0.3 mas, we study a particularly low-activity state of the source, and estimate the nuclear region brightness temperature, comparing with the extreme one detected one year before during the RadioAstron early science period. We also make use of the VLBA-BU-BLAZAR survey data, at 43 GHz, to study the kinematics of the jet in a 1.5-year time window. We find that the nuclear brightness temperature is two orders of magnitude lower than the exceptionally high value detected in 2013 with RadioAstron at the same frequency (1.4x10^13 K, source-frame), and even one order of magnitude lower than the equipartition value. The kinematics analysis at 43 GHz shows that a new component was ejected 2 months after the 2013 epoch, visible also in our 22 GHz map presented here. Consequently this was located upstream of the core during the brightness temperature peak. These observations confirm that the previously detected extreme brightness temperature in 3C 273, exceeding the inverse Compton limit, is a short-lived phenomenon caused by a temporary departure from equipartition. Thus, the availability of interferometric baselines capable of providing {\mu}as angular resolution does not systematically imply measured brightness temperatures over the known physical limits for astrophysical sources.Comment: Accepted for publication in A&

    Toxicity study in a pig model of intraperitoneal collagenase as an “enzymatic scalpel” directed to break stroma in order to generate a new perspective for peritoneal carcinomatosis approach: an experimental research

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    Background: This study aimed to measure the toxicity resulting from collagenase administration to the peritoneal cavity in a pig model as a preliminary step to break down the stroma surrounding tumors. Methods: Eight pigs were treated with 2 different collagenase concentrations previously tested in rats by our group. Time and temperature were controlled using a peritoneal lavage system (PRS System, Combat Medical Ltd.) identical to that used in human surgeries through hyperthermic intraperitoneal chemotherapy (HIPEC); 2 additional pigs were treated with peritoneal lavage only. Samples of blood and peritoneal fluid were collected pre-treatment, immediately after treatment, and 24 h postoperatively. In addition, histological studies and blood collagenase levels were measured. Results: No complications were observed during the surgeries. Intraoperative images evidenced the release of peritoneal tissue during collagenase treatment. After surgery, the animals showed no signs of pain. Diet and mobility were normal at 4 h postoperatively, and there were no significant differences in hematologic or biochemical parameters. Quantification of MMP1 and MMP2 in all samples as measured by absorbance showed no differences in blood collagenase levels between pre-treatment, post-treatment, and 24 h postoperatively. None of the animals treated with collagenase showed peritoneal adhesions during the second surgery. Histologically, peritoneal organs and serous structures did not show any microscopic alterations associated with collagenase treatment in any group. Conclusion: Lavage of the peritoneal cavity with doses of up to 100,000 collagen digestion units/animal for 30 min is safe and removes connective tissue from the peritoneal cavity

    Psychophysiological condition in the performance of sanitary-military tasks with surgical mask

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    Using a quasi-experimental design with 19 health workers (33.7 ± 5.1 years), the importance of physical and cognitive condition and performance when wearing protective equipment with a surgical mask during training situations in significant contexts of military intervention has been analysed. Heart rate and its variability, glucose levels, thermoregulation, explosive strength and perceived effort in specific motor performance tasks (tapping test, tourniquet, ammunition), and cognitive and decisional performance (triage) were measured. The results indicate significant differences (p < 05) depending on the physical condition (blood glucose and explosive strength), gender (explosive strength and tourniquet), smoking habit (perceived effort) and specialty (glucose level) in the study group. In conclusion, the importance of physical and psychological training is highlighted to improve the operational response in health-military situations that require the use of a surgical maskSe ha analizado, mediante un diseño cuasi-experimental con 19 sanitarios (33.7 ± 5.1 años), la importancia de la condición física, cognitiva y el rendimiento al portar un equipo de protección con mascarilla quirúrgica durante situaciones de entrenamiento en contextos significativos de intervención militar. Se midieron la frecuencia cardíaca y su variabilidad, los niveles de glucosa, la termorregulación, la fuerza explosiva y el esfuerzo percibido en tareas de rendimiento motor específicas (tapping test, torniquete, municionamiento), y de rendimiento cognitivo y decisional (triaje). Los resultados indican diferencias significativas (p < 05) en función de la condición física (glucemia y fuerza explosiva), del género (fuerza explosiva y torniquete), del hábito tabáquico (esfuerzo percibido) y del cuerpo de pertenencia (nivel de glucemia) en el grupo de estudio. Como conclusión, se destaca la importancia del entrenamiento físico y psicológico para la mejora de la respuesta operativa en situaciones sanitario-militares que requieren el uso de mascarilla quirúrgic

    Primary Hepatosplenic Large B-Cell Lymphoma: A Rare Aggressive Tumor

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    Diffuse large B-cell lymphoma is the most common form of lymphoma. It usually begins in the lymph nodes; up to 40% may have an extranodal presentation. According to a definition of primary extranodal lymphoma with presentation only in extranodal sites, there are reports of large B-cell lymphomas limited to liver or spleen as separate entities, and to date there have been only three documented cases of primary hepatosplenic presentation. This paper reports a fourth case. Due to a review of the literature and the clinical course of the case reported, we conclude that primary hepatosplenic large B-cell lymphoma has been found predominantly in females older than 60 years. The patients reported had <2 months of evolution prior to diagnosis, prominent B symptoms, splenomegaly in three and hepatomegaly in two, none with lymph node involvement. All had thrombocytopenia and abnormal liver function tests; three had anemia and elevated serum lactic dehydrogenase levels, two with hemophagocytosis in bone marrow. Because of the previously mentioned data, it can be stated that primary hepatosplenic lymphoma is an uncommon and aggressive form of disease that requires immediate recognition and treatment
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