Relativistic heavy-ion physics

The study of relativistic heavy-ion collisions is an important part of the LHC research programme at CERN. This emerging field of research focuses on the study of matter under extreme conditions of temperature, density, and pressure. Here we present an introduction to the general aspects of relativistic heavy-ion physics. Afterwards we give an overview of the accelerator facility at CERN and then a quick look at the ALICE project as a dedicated experiment for heavy-ion collisions.Comment: 23 pages, Lectures given at the 5th CERN-Latin-American School of High-Energy Physics, Recinto Quirama, Colombia, 15 - 28 Mar 200

The ALICE experiment at the LHC: a status review

ALICE is one of the big experiments at the LHC. It focuses on the study of heavy ion collisions at ultra-relativistic energies. Its main goal is to observe a transition of ordinary matter into a plasma of quarks and gluons. Here we review the status of the experiment just before data taking starts. Cosmic ray studies as well as the results of the past beam tests show the potential of the detector

Double Penalty in Returns to Education: Informality and Educational Mismatch in the Colombian Labour market

This paper examines the returns to education taking into consideration the existence of educational mismatches in the formal and informal employment of a developing country. Results show that the returns of surplus, required and deficit years of schooling are different in the two sectors. Moreover, they suggest that these returns vary along the wage distribution, and that the pattern of variation differs for formal and informal workers. In particular, informal workers face not only lower returns to their education, but suffer a second penalty associated with educational mismatches that puts them at a greater disadvantage compare to their formal counterparts

Informality and Overeducation in the Labor Market of a Developing Country

In this paper, we explore the connection between labor market segmentation in two sectors, a modern protected formal sector and a traditionalunprotected-informal sector, and overeducation in a developing country. Informality is thought to have negative consequences, primarily through poorer working conditions, lack of social security, as well as low levels of productivity throughout the economy. This paper considers an aspect that has not been previously addressed, namely the fact that informality might also affect the way workers match their actual education with that required performing their job. We use micro-data from Colombia to test the relationship between overeducation and informality. Empirical results suggest that, once the endogeneity of employment choice has been accounted for, formal male workers are less likely to be overeducated. Interestingly, the propensity of being overeducated among women does not seem to be closely related to the sector choice

Development and Validation of an X-ray Imaging Detector for Digital Radiography at Low Resolution

Digital X-ray detectors are required in different sciences and applications, however many high quality devices are expensive although high-resolution images are not always required. We present an easy way to build a detector capable of forming X-ray digital images and video with a very large area (18×18 cm2). The detector is formed by three main components: scintillator, optics lenses and CCD sensor. Basically, the device converts the X-rays into visible light which is then collected by the CCD sensor. The scintillator is Gadox type, from Carestream®, 18×18 cm2, regular type, lambda 547 nm. The optics lenses are generic, with manual focus and widely visual field. The CCD sensor has a size of 1/3″, 752 × 582 pixels, monochrome, 20 FPS, 12 bits ADC and pixel size of 3.8 μm. With the built detector and an X-ray source, we formed an X-ray imaging detection system to generate digital radiographs of biological or inert objects-examples are given-, as well as real-time X-ray video. Additionally, the spatial resolution limit was measured in terms of Modulation Transfer Function by the method of opaque edge from a lead sheet with a result of 1.1 Lp/mm. Finally using a filter, the focal spot of the X-ray source is measured, resulting in a diameter of 0.9 mm (FWHM)

A Method to Shorten Signals in SM-OFDM

Spatial modulation (SM) added to traditional OFDM communications has been intensively studied as a candidate transmission method to convey high-speed, low-delay, powerefficient and high-mobility 5G communications in a reliable basis. This approach implies the use of multiple antennas at the transmitter. Then, the fundamental aspect revised in this work takes into account that in a single-carrier SM system, the selection of the active transmit antenna according to (part of) the information bits makes it possible to use a single power amplifier (PA) that is switched among the available antennas. On the other hand, in a conventional SM-OFDM system, every antenna needs to be continuously active as the index information is typically different for each subcarrier. Consequently, we propose a transmission scheme that precodes the information symbols in frequency domain, such that the global symbol period is split into partitions that enable a sequential operation of antennas which can be fed by a single PA. In addition, it is possible to establish that the proposed approach tends to be more robust against disturbances observed in high mobility environments.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Estudio de la investigación turística a través de las coautorías de artículos: cálculo de indicadores de colaboración y análisis de redes sociales

Se analiza la colaboración científica de las universidades catalanas en el campo del turismo entre 2000 y 2010. A partir de las coautorías de artículos, se calculan indicadores de colaboración simples y se examina la red colaboración. Se estudia la colaboración entre investigadores, instituciones y territorios. Los resultados muestran un aumento de la colaboración, diferencias entre las revistas y ausencia de relación entre colaboración y multidisciplinariedad. La red de colaboración presenta una baja densidad y varias subredes.Catalan universities scientific collaboration in tourism is analyzed, from 2000 to 2010. Through coauthorship data, simple collaboration indicators are calculated and the collaboration network is examined. Collaboration among researchers, institutions and territories is investigated. Results show an increase in collaboration, differences among journals, and absence of relationship between collaboration and multidisciplinarity. The collaboration network presents a low density and several subnetworks

A Method to Shorten Signals in SM-OFDM

Spatial modulation (SM) added to traditional OFDM communications has been intensively studied as a candidate transmission method to convey high-speed, low-delay, powerefficient and high-mobility 5G communications in a reliable basis. This approach implies the use of multiple antennas at the transmitter. Then, the fundamental aspect revised in this work takes into account that in a single-carrier SM system, the selection of the active transmit antenna according to (part of) the information bits makes it possible to use a single power amplifier (PA) that is switched among the available antennas. On the other hand, in a conventional SM-OFDM system, every antenna needs to be continuously active as the index information is typically different for each subcarrier. Consequently, we propose a transmission scheme that precodes the information symbols in frequency domain, such that the global symbol period is split into partitions that enable a sequential operation of antennas which can be fed by a single PA. In addition, it is possible to establish that the proposed approach tends to be more robust against disturbances observed in high mobility environments.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Competitividad Internacional del Arroz Mexicano: un análisis con base en datos de comercio exterior

Rice is one of the fundamental crops for feeding Mexicans and also one of those that has suffered severe setbacks in its production over the last few years. This study, with descriptive ambitions, aims to assess the competitiveness of Mexican rice in international markets, through the analysis of four indicators: the value of exports, the trade balance, the index of food self-sufficiency and the index of commercial openness, for a period from 2012 to 2021 (in the first two indicators) and from 2010 to 2018 (in the aforementioned indices). The results suggest that Mexico lacks the capacity to compete in international rice markets, that it is highly dependent on imports of this crop, and that this dependence has tended to deepen over time.El arroz es uno de los cultivos fundamentales para la alimentación de los mexicanos y también uno de los que han sufrido severos retrocesos en su producción a lo largo de los últimos años. El presente estudio, con ambiciones descriptivas, tiene por objetivo evaluar la competitividad del arroz mexicano en los mercados internacionales, mediante el análisis de cuatro indicadores: el valor de las exportaciones, el saldo comercial, el índice de autosuficiencia alimentaria y el índice de apertura comercial, para un periodo comprendido de 2012 a 2021 (en los primeros dos indicadores) y de 2010 a 2018 (en los índices mencionados). Los resultados sugieren que México carece de capacidad para competir en los mercados internacionales del arroz, que es altamente dependiente de las importaciones de este bien para solventar su consumo interno, y que dicha dependencia ha tendido a profundizarse con el paso del tiempo. &nbsp

Informality and overeducation in the labor market of a developing country

In this paper, we explore the connection between labor market segmentation in two sectors, a modern protected formal sector and a traditional- unprotected-informal sector, and overeducation in a developing country. Informality is thought to have negative consequences, primarily through poorer working conditions, lack of social security, as well as low levels of productivity throughout the economy. This paper considers an aspect that has not been previously addressed, namely the fact that informality might also affect the way workers match their actual education with that required performing their job. We use micro-data from Colombia to test the relationship between overeducation and informality. Empirical results suggest that, once the endogeneity of employment choice has been accounted for, formal male workers are less likely to be overeducated. Interestingly, the propensity of being overeducated among women does not seem to be closely related to the employment choice