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Simulación Monte Carlo para determinar la dosis absorbida utilizando braquiterapia con una tasa alta de dosis concomitante a un campo magnético

FERNANDO MORENO BARBOSA (2020)

"En general, utilizar las simulaciones Monte Carlo a través de la herramienta TOPAS para

realizar un estudio comparativo en un escenario realista utilizando imágenes DICOM de

pacientes con diagnóstico de cáncer de pulmón.

En particular, validar TOPAS para aplicaciones de braquiterapia de tasa alta de dosis con

192Ir. Además, modelar el efecto de los campos magnéticos en la distribución de dosis con

192Ir usando geometrías simples y con material homogéneo. También, evaluar el efecto sobre

las distribuciones de dosis durante los tratamientos de braquiterapia de pulmón utilizando

una fuente de 192Ir dentro de un escáner de imagen por resonancia magnética (MRI, Magnetic

Resonance Imaging) en condiciones similares de tratamiento con la variante de presencia o

ausencia de un campo magnético estático.

Para alcanzar estos objetivos, se calcularon las distribuciones de dosis en un material

pulmonar homogéneo de baja densidad utilizando espectros de electrones mono y

polienergéticos, lo cual permitió evaluar los mejores y los peores escenarios en presencia o

ausencia de un campo magnético uniforme y externo."

Doctoral thesis

Braquiterapia con radioisótopos Campos magnéticos--Medición Materiales magnéticos Método Montecarlo--Programas de ordenador Física médica Radiología CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA

Submm/mm Galaxy Counterpart Identification Using a Characteristic Density Distribution

Itziar Aretxaga David Hughes (2013)

We present a new submm/mm galaxy counterpart identification technique whichbuilds on the use of Spitzer IRAC colors as discriminators between likely counter-parts and the general IRAC galaxy population. Using 102 radio- and SMA-confirmedcounterparts to AzTEC sources across three fields (GOODS-N, GOODS-S, and COSMOS), we develop a non-parametric IRAC color-color characteristic density distribution (CDD), which, when combined with positional uncertainty information vialikelihood ratios, allows us to rank all potential IRAC counterparts around SMGsand calculate the significance of each ranking via the reliability factor. We reportall robust and tentative radio counterparts to SMGs, the first such list available forAzTEC/COSMOS, as well as the highest ranked IRAC counterparts for all AzTECSMGs in these fields as determined by our technique. We demonstrate that the technique is free of radio bias and thus applicable regardless of radio detections. For observations made with a moderate beamsize (∼18′′), this technique identifies ∼85 percent of SMG counterparts. For much larger beamsizes (≳30′′), we report identificationrates of 33-49 per cent. Using simulations, we demonstrate that this technique is animprovement over using positional information alone for observations with facilities such as AzTEC on the LMT and SCUBA-2 on JCMT.

Article

Submillimetre: galaxies Radio continuum: galaxies Infrared: galaxies Galaxies: high redshift Techniques: photometric Methods: data analysis CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA ASTRONOMÍA Y ASTROFÍSICA RADIOASTRONOMÍA RADIOASTRONOMÍA

Emulación de la capa física de un sistema de comunicaciones DFTS-OFDM inalámbrico operando en modo full-duplex en banda (IBFD)

A DFTS-OFDM wireless system physic layer implementation operating in In-Band full-duplex mode (IBFD)

SERGIO ARMAS JIMENEZ (2021)

Se implementó la capa física de un sistema inalámbrico de comunicaciones que contempla multiplexado por división de frecuencias ortogonales (OFDM, por sus siglas en inglés) y esparcimiento con la transformada discreta de Fourier (DFTS, por sus siglas en inglés), DFTS-OFDM, operando en modo Full-Duplex (FD). La plataforma de implementación fue el software de GNU Radio junto con el hardware de USRP (siglas en inglés de Universal Software Radio Peripheral). La operación de un nodo FD requiere de la disminución al máximo de la señal de auto-interferencia (SI, por sus siglas en inglés); para conseguirlo, se aplicaron cuatro técnicas: dos en el dominio de la propagación y dos más en el digital. En el dominio de RF se aplicó supresión pasiva de SI con el acomodo ortogonal entre los campos electromagnéticos de las antenas transmisora (Tx) y receptora (Rx), y supresión activa con la generación de una señal canceladora de SI. Las técnicas aplicadas en el dominio digital son contribuciones originales y tienen como objetivo mejorar la calidad del enlace, facilitando la cancelación del residual de la señal de SI. La primera técnica consiste en esparcir los datos digitalmente modulados con la aplicación de una DFT, previo a la formación del símbolo OFDM, generando una señal DFTS-OFDM. Con el símbolo DFTS-OFDM se consiguen dos beneficios importantes: una ganancia de codificación a la carga y el cambio de la señal con prominentes picos de potencia a una más homogénea. La segunda técnica propone utilizar símbolos OFDM con distinta cantidad de sub-portadoras (S-P, en delante), lo que produce dos sistemas virtualmente distintos coexistiendo en el mismo canal, sin posibilidad de sincronizarse erróneamente. Las primeras dos técnicas permiten atenuar la señal de SI, mientras que las dos técnicas propuestas como novedad en este trabajo, la harán ver como ruido gaussiano, facilitando su cancelación y la recuperación de la señal de interés en el nodo FD. El funcionamiento del nodo FD fue probado en un esquema de tres nodos, el cual permite tener dos enlaces distintos, operando simultáneamente sobre el mismo ancho de banda. Dos de los nodos en dicho esquema son de tipo half-duplex (HD), los cuales se enlazan al nodo FD, actuando uno como Tx y otro como Rx. Para aislar los nodos HD entre sí, se diseñó una caja con material absorbente de RF. El desempeño global al aplicar las técnicas de SIC, se midió en términos de tasa de bit erróneo (BER, por sus siglas en inglés) en función ...

The physical layer of a wireless communication system that applies orthogonal frequency division multiplexing (OFDM) and spreading with the discrete Fourier transform (DFTS), DFTS-OFDM, operating in Full-Duplex (FD) mode, was implemented in this thesis, using GNU (GNU’s Not Unix) Radio software and universal software radio peripheral (USRP) hardware technology. The FD operation on a device requires the reduction to a minimum level of the self-interference (SI) signal. To achieve this, four techniques were applied: two in the radio frequency (RF) domain and two in the digital domain. In the RF domain, a passive suppression is obtained by placing the transmitter (Tx) and receiver (Rx) antennas such that they generate orthogonal electromagnetic fields. Also, an active signal suppression is achieved, by generating a local SI cancellation (SIC) signal, then the obtained SIC and the Rx signals are combined and the resulting signal is feeding to the low noise amplifier at the FD receiver node. The techniques applied in the digital domain are original contributions and aim to improve the quality of the link, facilitating the cancellation of the SI signal. The first technique consists of spreading the digitally modulated data with the application of a DFT, prior to the formation of the OFDM symbol, generating a DFTS-OFDM signal. Two important benefits are achieved with the DFTS-OFDM technique: a coding gain on payload data and the shift of the signal with prominent power peaks to one with more homogeneous behavior. The second technique proposes to use OFDM symbols with different amount of sub-carriers (S-P), which produces two virtually different systems coexisting on the same channel, without the possibility of being erroneously synchronized. The first two techniques make it possible to attenuate the SI signal, while the two digital techniques, proposed as a novelty in this work, will make it look like gaussian noise, facilitating its cancellation and the recovery of the signal of interest at the FD node. The operation of the FD system was tested in a three-node scheme, using two additional half-duplex (HD) type nodes. The three node scheme allows to have two different links, operating simultaneously on the same bandwidth. To guarantee minimal interference between the HD nodes (linked to the FD node, one acting as Tx and the other as Rx), a box with RF absorbing material was designed, which allowed them to be isolated. Overall performance when applying SIC ...

Doctoral thesis

FD, IBFD, DFTS-OFDM, SIC, GNU Radio, USRP FD, IBFD, DFTS-OFDM, SIC, GNU Radio, USRP INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA DE LAS TELECOMUNICACIONES DISPOSITIVOS FOTOELÉCTRICOS DISPOSITIVOS FOTOELÉCTRICOS

High-Resolution Broadband Millimeter-Wave Astrophysical Spectrometer with Triple Product Acousto-Optical Processor

MIGUEL CHAVEZ DAGOSTINO ALEXANDER SHCHERBAKOV Adán Omar Arellanes Bernabe Vahram Chavushyan (2013)

An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as one of the potential observational infrastructures where the acousto-optical spectrometer can be successfully used. A summary on the study of molecular gas in relatively old (age > 10 Myr) disks around main sequence stars is provided. We have identified this as one of the science cases in which the proposed processor can have a big impact. Then we put forward triple product acousto-optical processor is able to realize algorithm of the space-and-time integrating, which is desirable for a wideband spectrum analysis of radio-wave signals with an improved resolution providing the resolution power of about 105 - 106 . It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this algorithm is based on exploiting the chirp Z-transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of developing the triple product acousto-optical processor in frames of the astrophysical instrumentation is shortly discussed.

Article

Astrophysical Instrumentation Radio-Astronomy Millimeter-Wave Spectrometer Space-and-Time Integrating Acousto-Optical Devices Optical Processing System CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Studies on CIS thin Films Deposited by R. F. Sputtering and CdS Nanoparticles Deposited by Microwave Assisted CBD for Photovoltaic Aplications

Rodrigo Cué Sampedro Soberanis (2009)

La conversión de energía por medio de dispositivos fotovoltaicos es una alternativa viable para reducir las emisiones que contribuyen al calentamiento global. En la actualidad el silicio representa el principal material empleado en las celdas fotovoltaicas, el cual debe

tener una pureza muy elevada y una estructura cristalina casi perfecta. Esto representa procesos muy caros que elevan el costo del producto y hace que la conversión de energía lumínica no sea una opción competitiva en comparación con la generación de energía por medio de combustibles fósiles.

Article

INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA DE LAS TELECOMUNICACIONES RADIOONDAS Y MICROONDAS

The connection between jets and host galaxies of radio loud AGN: Blazars vs NLSy1s

Alejandro Olguín Iglesias (2018)

This doctoral dissertation discuss the main properties of the host galaxies of those active galactic nuclei (AGN) capable of generating strong relativistic jets (and therefore, capable of emitting up to the γ−ray energy ranges) and with their jets pointing very close to the line of sight, namely; blazars (including flat spectrum radio quasars [FSRQ] and BL Lac objects [BL Lac]) and narrow-line Seyfert 1 galaxies (NLSy1s). Our aim is to identify galaxy properties that might influence its AGN and vice versa. Despite the progress on AGN research and important results such as the correlation found between the spheroid (elliptical galaxies or bulges in disc galaxies) properties and its central super massive black hole mass (which suggests a link between evolutionary processes of the galaxy and its black hole and hence, a likely relation between the host galaxy and its AGN) the relation between the jet that some AGN are capable to launch and its black hole remains unclear, although it is essential for the understanding of the energy release mechanisms and AGN evolution. Motivated by this, in this thesis work I take advantage of Nordical Optical Telescope (NOT) near infrared (nir) imagery and perform a homogeneous and systematic structural modeling of a sample of radio–loud AGN with prominent relativistic jets and redshifts 0.3 < z < 1.0 and also, compile host galaxy and nuclear magnitudes for radio–loud AGN from literature. The combined sample (our analysis and the compilation) contains 100 radio-loud AGN with host galaxy detections and a broad range of radio luminosities L1.4GHz ∼ 1023.7 − 1023.7W Hz−1 , allowing us to divide our blazars sample into high-luminosity blazars (HLBs) and low-luminosity blazars (LLBs). The main results of this part of the thesis was published in Olguin-Iglesias et al. (2016) where We found that the host galaxies of our sample are bright and seem to follow the µe − Reff relation for ellipticals and bulges (Kormendy relation). The two populations of blazars show different behaviors in the Mnuc −Mbulge plane, a statistically significant correlation is observed for HLBs and a constant Mbulge for the whole range of Mnuc of LLB. As shown by previous studies, we find that both blazar types are hosted by massive red elliptical galaxies; the so called, jet paradigm.

Doctoral thesis

Host galaxies AGN Radio Loud AGN NLSy1 Seyfert galaxy CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA ASTRONOMÍA Y ASTROFÍSICA ASTRONOMÍA Y ASTROFÍSICA

OH Maser Sources in W49N: Probing Magnetic Field and Differential Anisotropic Scattering with Zeeman pairs using the VLBA

Eduardo Mendoza Torres (2013)

Our analysis of a VLBA 12-hour synthesis observation of the OH masers in awell-known star-forming region W49N has yielded valuable data that enables usto probe distributions of magnetic fields in both the maser columns and the inter-vening interstellar medium (ISM). The data consisting of detailed high angular-resolution images (with beam-width ∼20 milli-arc-seconds) of several dozen OH maser sources or spots, at 1612, 1665 and 1667 MHz, reveal anisotropic scatter broadening, with typical sizes of a few tens of milli-arc-seconds and axial ratios between 1.5 to 3. Such anisotropies have been reported earlier by Desai, Gwinn & Diamond (1994) and interpreted as induced by the local magnetic field parallel tothe Galactic plane. However, we find a) the apparent angular sizes on the averagea factor of about 2.5 less than those reported by Desai et al. (1994), indicating significantly less scattering than inferred earlier, and b) a significant deviation inthe average orientation of the scatter-broadened images (by ∼10 degrees) from that implied by the magnetic field in the Galactic plane. More intriguingly, for afew Zeeman pairs in our set, significant differences (up to 6σ) are apparent in thescatter broadened images for the two hands of circular polarization, even when apparent velocity separation is less than 0.1 km s⁻¹. This may possibly be the first example of a Faraday rotation contribution to the diffractive effects in the ISM. Using the Zeeman pairs, we also study the distribution of magnetic field inthe W49N complex, finding no significant trend in the spatial structure function.In this paper, we present the details of our observations and analysis leading tothese findings, discuss implications of our results for the intervening anisotropic magneto-ionic medium, and suggest the possible implications for the structure of magnetic fields within this star-forming region.

Article

Masers ISM: molecules Magnetic fields Individual (W49N) Radio lines: ISM Structure function CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA ASTRONOMÍA Y ASTROFÍSICA ASTRONOMÍA Y ASTROFÍSICA

MILLIMETER AND SUBMILLIMETER COUNTERPARTS OF THE 2009 SEPTEMBER 26 SOLAR PROMINENCE

José Eduardo Mendoza Torres (2013)

We present observations of the millimeter and submillimeter wavelength radio emission from an extended solar prominence. The data were obtained at the Solar Submillimeter Telescope (SST) during regular observation son 2009 September 26. The prominence signals were detected at 1.41 mm (212 GHz) and 0.74 mm (405 GHz) in an east-west raster practiced on the solar disk. Detection was confirmed by the He II image from the Extreme Ultraviolet Imaging Telescope of the Solar and Heliospheric Observatory (EIT/SOHO). The peak brightness temperature at the 1.41 mm and 0.74 mm are separatedby ∼4 arcmin with the 0.74 mm one closer to the solar limb. Assuming a free-free emission mechanism, both peak intensities correspond to an excess of brightness temperature of Tb ∼2×10³ K and they are consistent with an electron temperature and density of Te∼5.6 × 10³ K and ne∼ 10¹⁰ cm¯³, respectively.

Presentamos observaciones en longitudes de onda milimétricas y submilimétricas de una prominencia solar extendida. Los datos fueron obtenidos en el Solar Submillimeter Telescope (SST) durante observaciones rutinarias el 29 de septiembre de 2009. Las radio señales fueron detectadas a 1.41 mm (212 GHz) y 0.74 mm (405 GHz) durante un barrido de este a oeste realizado sobre el disco solar. La detección fue confirmada por medio de la imagen de He II del Extreme Ultraviolet Imaging Telescope del Solar and Heliospheric Observatory (EIT/SOHO). Los máximos de las temperaturas de brillo a 1.41 mm y 0.74 mm están separados por ∼4 minutos de arco y la emisión a 0.74 mm es más cercana al limbo solar. Suponiendo un mecanismo de emisión del tipo libre-libre, ambos máximos corresponden a un exceso en la temperatura de brillo de Tb ∼2×10³ K, consistente con una temperatura y densidad electrónica de Te∼5.6 × 10³ K y ne∼ 10¹⁰ cm¯³, respectivamente.

Article

Sun: filaments, prominences Sun: radio radiation Sun: UV radiation CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA ASTRONOMÍA Y ASTROFÍSICA ASTRONOMÍA Y ASTROFÍSICA

THE CHROMOSPHERIC SOLAR MILLIMETER-WAVE CAVITY ORIGINATES IN THE TEMPERATURE MINIMUM REGION

Victor De la Luz (2013)

We present a detailed theoretical analysis of the local radio emission at the lower part of the solar atmosphere. To accomplish this, we have used a numerical code to simulate the emission and transport of high-frequency electromagnetic waves from 2 GHz up to 10 THz. As initial conditions, we used VALC, SEL05, and C7 solar chromospheric models. In this way, the generated synthetic spectra allow us to study the local emission and absorption processes with high resolution in both altitude and frequency. Associated with the temperature minimum predicted by these models, we found that the local optical depth at millimeter wavelengths remains constant, producing an optically thin layer that is surrounded by two layers of high local emission. We callthis structure the Chromospheric Solar Millimeter-wave Cavity (CSMC). The temperature profile, which features temperature minimum layers and a subsequent temperature rise, produces the CSMC phenomenon. The CSMCshows the complexity of the relation between the theoretical temperature profile and the observed brightness temperature and may help us to understand the dispersion of the observed brightness temperature in the millimeter wavelength range.

Article

Methods: numerical Radiation mechanisms: thermal Radiative transfer Stars: chromospheres Sun: chromosphere Sun: radio radiation CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA ASTRONOMÍA Y ASTROFÍSICA ASTRONOMÍA Y ASTROFÍSICA