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9 results, page 1 of 1

THE ATACAMA COSMOLOGY TELESCOPE: DATA CHARACTERIZATION AND MAPMAKING

David Hughes (2013)

We present a description of the data reduction and mapmaking pipeline used for the 2008 observing season of theAtacama Cosmology Telescope (ACT). The data presented here at 148 GHz represent 12% of the 90 TB collected by ACT from 2007 to 2010. In 2008 we observed for 136 days, producing a total of 1423 hr of data (11 TB for the 148 GHz band only), with a daily average of 10.5 hr of observation. From these, 1085 hr were devoted to an 850 deg² stripe (11.2 hr by 9º.1) centered on a declination of −52º.7, while 175 hr were devoted to a 280 deg² stripe (4.5 hrby 4º.8) centered at the celestial equator. The remaining 163 hr correspond to calibration runs. We discuss sourcesof statistical and systematic noise, calibration, telescope pointing, and data selection. For the 148 GHz band, out of 1260 survey hours and 1024 detectors in the array, 816 hr and 593 effective detectors remain after data selection, yielding a 38% survey efficiency. The total sensitivity in 2008, determined from the noise level between 5 Hz and 20 Hz in the time-ordered data stream (TOD), is 32μK√s in cosmic microwave background units. Atmospheric brightness fluctuations constitute the main contaminant in the data and dominate the detector noise covariance atlow frequencies in the TOD. The maps were made by solving the least-squares problem using the Preconditioned Conjugate Gradient method, incorporating the details of the detector and noise correlations. Simulations, as wellas cross-correlations with Wilkinson Microwave Anisotropy Probe sky maps on large angular scales, reveal thatour maps are unbiased at multipoles ℓ >300. This paper accompanies the public release of the 148 GHz southern stripe maps from 2008. The techniques described here will be applied to future maps and data releases.

Article

Genealogía del Arte digital mexicano, análisis de los aspectos vinculantes al diseño

Article

Sensitivity of the High Altitude Water Cherenkov Detector to Sources of Multi-TeV Gamma Rays

The High Altitude Water Cherenkov (HAWC) observatory is an array oflarge water Cherenkov detectors sensitive to gamma rays and hadronic cosmicrays in the energy band between 100 GeV and 100 TeV. The observatory willbe used to measure high-energy protons and cosmic rays via detection of theenergetic secondary particles reaching the ground when one of these particlesinteracts in the atmosphere above the detector. HAWC is under constructionat a site 4100 meters above sea level on the northern slope of the volcano SierraNegra, which is located in central Mexico at 19ºN latitude. It is scheduledfor completion in 2014. In this paper we estimate the sensitivity of the HAWCinstrument to point-like and extended sources of gamma rays. The source fluxesare modeled using both unbroken power laws and power laws with exponentialcutoffs. HAWC, in one year, is sensitive to point sources with integral power-lawspectra as low as 5 × 10⁻¹³ cm⁻² sec⁻¹ above 2 TeV (approximately 50mCrab) over 5 sr of the sky. This is a conservative estimate based on simpleevent parameters and is expected to improve as the data analysis techniquesare refined. We discuss known TeV sources and the scientific contributions that HAWC can make to our understanding of particle acceleration in these sources.

Article

NF-κΒ and SOD expression in preeclamptic placentas

Background/aim: Preeclampsia is a leading cause of maternal death in the developing world. Our aim was to quantify and compare messenger (mRNA) expression of nuclear factor-kappa beta (NF-κΒ) and superoxide dismutase (SOD) in control patients with preeclampsia and without preeclampsia with or without familial hereditary background. Materials and methods: Four groups of patients were formed depending on the presence or absence of preeclampsia and presence or absence of familial history for preeclampsia. NF-κΒ and SOD were measured in human placentas by real-time quantitative polymerase chain reaction. The 2–ΔΔct analysis method was used to measure the difference in the relative expression of the target genes in each group of patients. Results: In NF-κΒ expression, there was an increase of 23.35% in the group of women with preeclampsia versus women with preeclampsia without familial history. Regarding SOD, there was a reduction of about 33.33% in the expression in women with preeclampsia with familial history versus women with preeclampsia without familial history. Conclusion: Familial presence of preeclampsia could predispose to altered expression in SOD and NF-κΒ.

This project was partially funded by PROMEP/103.5/09/7342, Secretaría de Educación Pública, Mexico, and the Asociación Científica Latina (ASCILA).

Article

Sensado de materiales con estructuras de microondas

In this work describes the design of a measure the complex dielectric permittivity of materials with microwaves. This circuit is sensor to based on novel technologies of literature; integrated substrate waveguide "SIW", cavity disturbance technique "CPT" and Epsilon near zero "ENZ". This novel sensor using substrate integrated waveguide is presented for dielectric properties characterization. The structure is miniaturized using Epsilon Near Zero technique. This technique has already been reported. However, it is demonstrated that a high Q structure can be obtained by increasing the tunnel thickness and modifying the external coupling. In addition, this structure is designed to be reconfigurable to two frequencies 2.4 GHz and 3.5 GHz by using liquid metal switches. Cavity perturbation technique is used to measure the dielectric permittivity of some liquids, where the experimental results are very close to the values reported in the literature for the measured samples.

Master thesis

Quantification of the sulfidation extent of Mo in CoMo HDS catalyst through XPS

Background removal in X-ray photoelectron spectroscopy (XPS) spectra was carried out in Co–Mo hydrodesulfurization (HDS) catalysts supported alumina using traditional and recent methods. The sulfidation extent, expressed by the XPS area ratio AMo3d-MoS2/AMo3d-Total, which is a fundamental parameter in the performance of a hydrodesulfurization catalyst, was obtained using different methodologies. The methods include the use of the background active approach, in which the background is optimized during peak-fitting. The method allows for the use of several types of backgrounds, which proved crucial for fitting the Mo 3d-S 2s and the S 2p–Si 2p regions. Both regions contain two overlapped elements, making fundamental a distinction between them. In these cases, a slope background subtraction was used in conjunction with the Shirley-Vegh-Salvi-Castle (SVSC) method to have a clear distinction between the different strengths of backgrounds arising from the overlapped peaks Mo 3d-S 2s and S 2p–Si 2p. From the resulting fitting, the relative percentage (% rel.) of each species present in Mo and S in the catalyst CoMoAl was obtained. The results were compared with those obtained using the static (traditional) approach. With these results, the sulfidation extent, an important parameter in the performance of the HDS catalyst was determined.

Adolfo-Romero Galarza thanks Consejo Nacional de Ciencia y Tecnologia (CONACyT), Mexico for their postdoctoral fellowship (ID. 1908/2010C ) . We acknowledge financial support from Direccion General de Asuntos del Personal Academico ( DGAPA) Mexico, UNAM , project PAPIIT-IN-113015 . The authors appreciate the support provided by Gustavo Gomez-Sosa (CINVESTAV-Qro.) for the acquisition of the XPS data and Alberto Herrera-Gómez (CINVESTAV-Unidad Queretaro, Mexico) for engaging in useful discussion regarding the spectra fitting and for providing computer program AANALYZER version 1.2.

Article

Study of the properties of cosmic-rays using the ALICE-LHC detector

EMMA GONZALEZ HERNANDEZ (2021)

"ALICE is one of the four main experiments at the CERN Large Hadron Collider. The

location of ALICE detector allows the study the muonic component of cosmic-rays, since

it is located 52 meters underground with 28 meters of rock above it. The ALICE detector

is able to detect atmospheric muons from extensive air showers, making possible the study

of cosmic-rays physics. At this depth, only atmospheric muons with energies greater

than 16 GeV can reach the detection zone of ALICE. A study of cosmic charge ratio is

presented for events of atmospheric showers collected in 2015, 2016, 2017 and 2018 by the

ALICE experiment. The whole data sample corresponds to 62.5 days of data taking. The

analysis of the multiplicity distribution of atmospheric muons reconstructed by the Time

Projection Chamber (TPC) of ALICE is also presented. The rate of high muon multiplicity

events (number of muons >100) was estimated and compared with the predictions given

by QGSJET-II-04, SIBYLL and EPOS-LHC."

Doctoral thesis

Microwave-assisted synthesis of the lipase-catalyzed ring-opening copolymerization of ε-caprolactone and ω-pentadecanolactone: Thermal and FTIR characterization

Microwave-assisted synthesis of the lipase-catalyzed ring opening polymerization of ε-caprolactone (ε-CL) and ω-pentadecanolactone (ω-PDL) monomers was studied. A series of P(CL-co-PDL), with different molar feed ratios, including (ε-CL/ω-PDL) 100/0, 75/25, 50/50, 25/75, and 0/100, were synthesized. The resulting polyesters were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The microwave-assisted polymerization of the monomers reached high conversions (91–95%) within 60 min. FTIR spectra showed the typical absorption bands of these polyesters. A very intense band in the carbonyl region, which was shifted from 1,720 cm−1 for PCL to 1,732 cm−1 for PPDL homopolymer, as well as peaks owing to methylene groups in the 2,990–2,850 cm−1 range. DSC results revealed that all polyester samples were semi-crystalline. Interestingly, the copolymers exhibited only one melting peak (Tm), and their Tm values linearly increased from 57°C to 95°C as PPDL concentration was increased. Thermal stability of polyesters also depended on PDL content; an increase in PDL concentration increases polymer degradation temperature (Td).

Article

Materia oscura de dos campos escalares

En esta tesis se analizaron las propiedades físicas de dos partículas tipo campo escalar como modelo de materia oscura. Particularmente consideramos campos escalares libres (potencial de energía cuadrático) con masa distinta. Escribimos las expresiones para la dinámica del fondo cosmológico en un espacio-tiempo tipo Friedman-Lemaitre-Robertson-Walker con curvatura espacialmente nula. Se calcularon las perturbaciones lineales sobre la métrica y las componentes que conforman el modelo, incluyendo los dos campos libres. Las ecuaciones del fondo cosmológico y las perturbaciones se reescriben por medio de sistemas dinámicos. Se estudia la evolución del sistema a través de soluciones numéricas y se aplican cortes a las oscilaciones relacionadas a los campos escalares, empleando una versión modificada del código CLASS (Cosmic Linear Anisotropy Solving System). Contrastamos nuestros resultados con las predicciones teóricas de la materia oscura fría, enfocándonos en el espectro de potencia de masas. El modelo de dos campos libres con rangos definidos en su masa logra evitar el conocido “corte abrupto” en el espectro de potencia de masas a pequeñas escalas, que presentan modelos de un solo campo escalar libre con masa ultraligera. También se emplea el criterio del área que utiliza resultados de simulaciones numéricas y lo extrapola para determina la viabilidad de nuevos modelos, a partir de la desviación en el espectro de potencia de masas respecto al modelo base $\Lambda$CDM. Por último, se usa el estimador de parámetros cosmológicos Monte Python con datos de Lyman-$\alpha$ inferidos de eBOSS (extended Baryon Oscillation Spectroscopic Survey), para obtener restricciones a las masas y densidades de los dos campos escalares.

Master thesis