Submissões Recentes

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    Sensitivity estimation for the future laser ionization diagnosis in inferring neutral particle density in the TCABR Tokamak

    2024 - ALBUQUERQUE, FERNANDO A.F.; WETTER, NIKLAUS U.; SEVERO, JOSE H.F.

    This study undertakes an estimation of photoionization occurrences and the ensuing reduction in hydrogen spectral line intensities via Laser-Induced Ionization. The objective is to quantify the sensitivity of the neutral particle density diagnostic.

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    Preclinical evaluation of red laser combined with radioactive gold nanoparticles in breast cancer

    2024 - PINTO, MAYARA S.; ROSERO, WILMER A.A.; ROSTELATO, MARIA E.M.C.; RIBEIRO, MARTHA S.

    Breast cancer remains a leading cause of mortality among women worldwide, underscoring the urgent need for innovative therapeutic strategies to improve both quality of life and survival rates. Nanobrachytherapy (NB) and photobiomodulation therapy (PBM) have emerged as promising, less invasive approaches to breast cancer treatment. NB offers the potential to deliver high doses of ionizing radiation more precisely and rapidly compared to conventional radiotherapy. Meanwhile, PBM has shown promise in sensitizing cells, particularly when administered prior to NB. In this study, we aimed to assess the efficacy of combining PBM with NB utilizing radioactive gold nanoparticles (AuNPs) in treating breast cancer in a murine model. Murine 4T1 cells were cultured in RPMI medium and subsequently injected into the lower-left mammary fat pad of the animals. Once the tumor reached approximately 0.1 cm3, AuNPs (approximately 200 μCi) were introduced into the mouse breast. The tumor was then exposed to red LED irradiation (660 nm, 40 mW, 150 s, 6 J) either once or twice. Animals were monitored for three weeks until euthanasia. Our findings revealed a significant inhibition of tumor growth in the NB group compared to the control, as well as the PBM + NB groups after one or two sessions. These results suggest that a single PBM session alone did not augment the effectiveness of NB in treating breast cancer. In conclusion, while our study underscores the potential of NB in restraining breast cancer progression, further investigation is warranted to elucidate the optimal combination and timing of PBM therapy to maximize its synergistic effects with NB.

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    Optical neural network for all-optical logic gates solution

    2024 - PRADO, FELIPE M.; WETTER, NIKLAUS U.

    With the escalating demand for speed and computational power to meet the ever-growing requirements of AI algorithms, coupled with the limitations of von Neumann computing, there is an increasing necessity for alternatives to silicon-based computers. Photonic computers emerge as a promising solution to this challenge, leveraging the low latency and parallelism of light to deliver unrivaled capabilities for neuromorphic computing. Notably, they offer significant reductions in energy consumption and substantial speed enhancements, allowing for matrix multiplications at the speed of light. These operations are particularly crucial as they constitute approximately 80% of computer usage in convolutional neural networks. In this work, we present an optical system capable of performing logic operations, such as AND, OR, NOT, and XOR, in an all-optical manner. This is made possible by utilizing a spatial light modulator (SLM), which receives and adjusts the input light according to the desired logic operation and input binary values. These values are encoded using a metal mask that segments a collimated light beam from a He-Ne laser. To incorporate not only the binary value of each bit but also the desired logic operation simultaneously, specific regions within a CCD sensor that receive the input beam after passing through the mask are defined. In a simplified approach, we designate the two lower quadrants of the CCD image to represent individual bits (lower left = bit 1; lower right = bit 2) and by detecting light intensity above a defined threshold, a logic value of '1' is assigned; otherwise, '0' is interpreted. Similarly, the same intuitive method can be applied to the upper quadrants to determine the logic operation (upper left = AND; upper right = OR). Further divisions of the CCD image can be implemented to accommodate additional operations or to create a bias beam, which is crucial for solving more complex problems. The analogy between this optical neural network and traditional networks can be drawn as follows: incident light on each SLM pixel forms the input vector, multiplied by a weight matrix via programmable phase delays. The resulting light, reflected by the SLM, is focused by a lens and captured by a CCD camera, effectively summing up the results to produce an output or new layer. The presented approach is particularly interesting for establishing a basis for future improvements and characterizations of optical non-linear activation functions.

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    Compact diode-pumped Nd:YLF laser with triple-wavelength emission

    2024 - PRADO, FELIPE M.; FRANCO, TOMAS J.; WETTER, NIKLAUS U.

    Here we present a compact and cost-effective Nd:YLF laser, capable of operating with either single- or multi-wavelength emission at 1047 nm, 1321 nm, or 1370 nm. The Nd:YLF crystal is side-pumped by a 797 nm emitting diode stack in a single-bounce resonator, featuring a concave highly reflective mirror with a radius of curvature of 8 m and a plane output coupler. The transmission of the laser mirrors is carefully selected to favor emissions with lower cross-sections, while still providing enough reflection for wavelengths with higher absorption. Through this technique alone, it was possible to select each wavelength or a combination thereof simply by aligning one laser mirror. This approach not only excels in terms of versatility, enabling multiple applications within the same laser setup, but also introduces innovative wavelength emission at 1370 nm. To the best of our knowledge, this represents the first reported instance of a transversally-pumped Nd:YLF emitting at this wavelength. This new wavelength holds great promise, primarily due to its proximity to the eye-safe region of the spectrum that can be achieved by additional Raman conversion. This characteristic opens a diverse range of potential applications, including Light Detection and Ranging (LIDAR), and range finding.