Light-cone quantization of two dimensional field theory in the path integral approach

A quantization condition due to the boundary conditions and the compatification of the light cone space-time coordinate $x^-$ is identified at the level of the classical equations for the right-handed fermionic field in two dimensions. A detailed analysis of the implications of the implementation of this quantization condition at the quantum level is presented. In the case of the Thirring model one has selection rules on the excitations as a function of the coupling and in the case of the Schwinger model a double integer structure of the vacuum is derived in the light-cone frame. Two different quantized chiral Schwinger models are found, one of them without a $\theta$-vacuum structure. A generalization of the quantization condition to theories with several fermionic fields and to higher dimensions is presented.Comment: revtex, 14 p

Matter-antimatter asymmetry without departure from thermal equilibrium

We explore the possibility of baryogenesis without departure from thermal equilibrium. A possible scenario is found, though it contains strong constraints on the size of the $CPT$ violation ($CPTV$) effects and on the role of the $B$ (baryon number) nonconserving interactions which are needed for it.Comment: Revtex, 4page

Comparison between Radiographic and Visual-Tactile Exams for the Detection and Assessment of Proximal Caries

Background: The optimal management of a caries lesion involves a precise and reliablediagnosis along with an appropriate treatment decision. The traditional diagnostic methodcontinues being the visual-tactile and it is focused in the detection of cavitated lesions.Currently, caries classification systems that include the early caries lesions and allow fornon-operative or operative treatment decisions are known. The radiography is known as acomplement for the current diagnosis of dental caries. The agreement between the visualtactileand the radiographic caries tests varies depending upon the caries prevalence. Purpose:To compare the number of proximal caries lesions detected radiographically and thevisual-tactile method. Methods: Visual-tactile (DMF-S criteria) and radiographic (bite-wingx-rays) examinations were conducted in 40 16-to-35 year olds. Results: The mean DMF-T was4.9±3.4 (D: 0.2±0.4; M: 0; F: 4.9±3.4). The visual-tactile exam in the posterior teeth showed amean DF-S of 5.0±4.0 (D: 0.2±0.5), and the radiographic of 16.0±3.4 (Radiolucency in dentine:2.9±1.7; in enamel: 13.1±3.3). The level of agreement (Kappa coefficient) between thevisual-tactile and the radiographic methods was insignificant (0.0012-0.08). Conclusion: Theradiographic exam detects 220 % more proximal caries lesions than the visual-tactile examin posterior teeth, which allows emphasizing the importance of the radiographic examinationfor the detection of dental caries.publishersversionPeer reviewe

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Identificación morfométrica y molecular de nematodos lesionadores de la raíz de Costa Rica. Nematropica

[EN] Root-lesion nematodes, Pratylenchus spp., are among the top three most significant nematode parasites of a wide range of vascular plants including several economically important crops. There are more than 100 described species. Identification at the species level is difficult due to morphological similarities and overlapping morphometric characters. This research was carried out between 2017 and 2019 with the aim of identifying Pratylenchus species associated with four crops in Costa Rica. Species of Pratylenchus were identified by their morphological features and with molecular methods. For molecular analysis, rDNA 28S expansion segments D2-D3 were amplified by PCR with D2A and D3B primers and the ITS1 region with the 18S and rDNA1 primers, which were subsequently sent for sequencing. Phylogenetic relationships between Pratylenchus species were established by Bayesian Inference, based on the sequences analyzed. Three species of Pratylenchus were detected: P. brachyurus associated with pineapple (Ananas comosus), P. coffeae with plantain (Musa paradisiaca), and P. zeae associated with rice (Oryza sativa) and star grass (Cynodon nlemfuensis). Of the three Pratylenchus species identified in this research, this is the first report of P. zeae associated with star grass in Costa Rica, however, this species had already been reported in rice in the country.[ES] Los nematodos lesionadores de raíces Pratylenchus spp. se encuentran entre las tres plagas de nematodos más importantes que parasitan una amplia gama de plantas vasculares, incluidos varios cultivos de importancia económica. Hay más de 100 especies descritas. La identificación a nivel de especie es difícil debido a las similitudes morfológicas y los caracteres morfométricos superpuestos. La presente investigación se llevó a cabo entre el 2017 y el 2019 con el objetivo de identificar especies de Pratylenchus asociadas a cuatro cultivos en Costa Rica. Se identificaron especies de Pratylenchus por sus características morfológicas y con métodos moleculares. Para los análisis moleculares se amplificaron por medio de PCR los segmentos de expansión D2-D3 del gen 28S del ADNr utilizando los cebadores D2A y D3B, y la región ITS1 con los cebadores 18S y rDNA1 los cuales posteriormente se enviaron a secuenciar. Se establecieron relaciones filogenéticas entre las especies de Pratylenchus por medio de Inferencia Bayesiana, con base en las secuencias analizadas. Se detectaron tres especies de Pratylenchus: P. brachyurus asociada al cultivo de piña (Ananas comosus L.), P. coffeae asociada con el cultivo de plátano (Musa paradisiaca) y P. zeae asociada a arroz (Oryza sativa) y a un cultivo de pasto estrella. De las tres especies de Pratylenchus identificadas en esta investigación, P. zeae se reporta por primera vez asociada a pasto estrella en Costa Rica; sin embargo, en el cultivo del arroz ya había sido previamente reportada.This research was supported by Laboratorio de Nematología at Universidad Nacional and funds FIDA (Fondo Institucional al Desarrollo Académico) from Universidad Nacional of Costa Rica.Peer reviewe

Identificación taxonómica y molecular de especies del nematodo lesionador de la raíz Pratylenchus (Nematoda: Pratylenchidae) asociado a cuatro cultivos de Costa Rica

Trabajo presentado en el 51st annual Organization of Nematologists of Tropical America meeting (ONTA 2019), celebrada en San José (Costa Rica) del 21 al 25 de julio de 2019.Identificar taxonómica y molecularmente especies del nematodolesionador de la raíz Pratylenchus asociadas a una plantación de arroz (Oryza sativa), plátano (Musasp.), piña (Ananas comosus) y pasto estrella (Cynodon nlemfuensis) para la toma de decisiones y el manejo de las plantaciones.Peer reviewe

Supersonic plasma beams with controlled speed generated by the alternative low power hybrid ion engine (ALPHIE) for space propulsion

The characteristics of supersonic ion beams from the alternative low power hybrid ion engine (ALPHIE) are discussed. This simple concept of a DC powered plasma accelerator that only needs one electron source for both neutral gas ionization and ion beam neutralization is also examined. The plasma production and space charge neutralization processes are thus coupled in this plasma thruster that has a total DC power consumption of below 450 W, and uses xenon or argon gas as a propellant. The operation parameters of the plasma engine are studied in the laboratory in connection with the ion energy distribution function obtained with a retarding-field energy analyzer. The ALPHIE plasma beam expansion produces a mesothermal plasma flow with two-peaked ion energy distribution functions composed of low and high speed ion groups. The characteristic drift velocities of the fast ion groups, in the range 36.6?43.5 km/s, are controlled by the acceleration voltage. These supersonic speeds are higher than the typical ion sound velocities of the low energy ion group produced by the expansion of the plasma jet. The temperatures of the slow ion population lead to ion Debye lengths longer than the electron Debye lengths. Furthermore, the electron impact ionization can coexist with collisional ionization by fast ions downstream the grids. Finally, the performance characteristics and comparisons with other plasma accelerator schemes are also discussed

Epidemiología del hipotiroidismo congénito en México Epidemiology of congenital hypothyroidism in Mexico

OBJETIVO: Describir las características epidemiológicas del hipotiroidismo congénito en recién nacidos en unidades médicas de la Secretaría de Salud de México. MATERIAL Y MÉTODOS: Estudio transversal en el cual se cuantificó tirotropina en 1 379 717 muestras de sangre de recién nacidos (de cordón umbilical o de talón), recolectadas en papel filtro, de enero de 2001 a diciembre de 2002, en unidades médicas de la Secretaría de Salud. Las muestras con tirotropina >15 µUI/ml para sangre de cordón, y > 10 µUI/ml para talón, se consideraron sospechosas, y se notificaron para realizar el perfil tiroideo y gammagrafía. Cuando los resultados fueron positivos, el caso se registró como hipotiroidismo congénito confirmado, y se anotaron los datos clínicos y demográficos en formatos específicos. Se utilizó estadística descriptiva estándar. RESULTADOS: Se encontró una prevalencia de 4.12 x 10 000 recién nacidos, con predominancia del sexo femenino (66.84%). Se observaron variaciones estatales en la prevalencia, máxima en Quintana Roo (8.13 x 10 000 recién nacidos) y mínima en Sinaloa (0.62 X 10 000). Se encontraron 57.46% tiroides ectópicas, 35.91% agenesias tiroideas y 6.63% defectos de la función de las hormonas tiroideas. Los principales datos clínicos fueron hernia umbilical (43.73%) e ictericia (41.58%). A 151 (17.12%) sospechosos no se les realizó estudio confirmatorio debido a datos incompletos o falsos en la ficha de identificación, fallecimiento del recién nacido, renuencia de los padres y cambio de domicilio. CONCLUSIONES: El hipotiroidismo se presentó en 1:2 426 recién nacidos, con predominio femenino (2:1), siendo la ectopia tiroidea su forma más común, y la hernia umbilical y la ictericia sus datos clínicos prominentes.<br>OBJECTIVE: To describe the epidemiological characteristics of congenital hypothyroidism (CH) in newborns (NB) detected by the Ministry of Health of Mexico (SSA). MATERIAL AND METHODS: A cross-sectional study was conducted. Thyroid stimulating hormone (TSH) was quantified in 1 379 717 blood samples of NB (from umbilical cord or heel prick), collected in Guthrie cards, between January 2001 and December 2002, in medical units of the SSA. The samples with TSH >15 mUI/ml for cord blood and >10 mUI/ml for heel blood were considered suspicious and were submitted for confirmation by thyroid hormone profile and/or scintigraphy. When the results were positive, the case was registered as confirmed CH and the clinical and demographic data were recorded in specific formats. Statistical analysis was performed using descriptive statistics. RESULTS: The prevalence of CH was 4.12x10,000 NB, with female predominance (66.84%). Regional variations in the prevalence were observed, the highest in Quintana Roo (8.13 x 10 000 NB) and the lowest in Sinaloa (0.62 X 10,000 NB). Abnormalities included 57.46% of ectopic glands, 35.91% of athyrosis, and 6.63% abnormal thyroid function conditions. The main clinical features were umbilical hernia (43.73%) and jaundice (41.58%). A total of 151 (17.12%) suspicious NB were not confirmed because of incomplete or inaccurate identification data, death of the NB, parent refusal, and change of address. CONCLUSIONS: CH was present in 1:2 426 NB, with a female predominance (2:1); an ectopic thyroid was the most common finding, and its prominent clinical features were umbilical hernia and jaundice

Hipertirotropinemia en recién nacidos mexicanos

Objetivo. Comunicar las diferencias encontradas en los niveles de concentración sanguínea de la hormona estimulante de la tiroides y su posible uso como indicador del estado de suficiencia de yodo en una muestra de recién nacidos mexicanos. Material y métodos. De septiembre de 1999 a agosto de 2000 se estudiaron 25 427 recién nacidos en unidades asistenciales de la Secretaría de Salud de cinco estados de la República Mexicana. Se analizaron 8 095 muestras de sangre de talón y 17 332 de cordón umbilical. La sangre fue recolectada en papel filtro y procesada mediante ensayo inmunoenzimático. Para el análisis estadístico se emplearon las pruebas U de Mann- Wittney, y de Kruskal-Wallis. Resultados. Se observó que 9.95% de las muestras de talón y 24.27% de las de cordón presentaron hipertirotropinemia (TSH>5 mUI/ml). Conclusiones. El porcentaje de muestras de hipertirotropinemia observado es mayor del esperado para una población con aporte suficiente de yodo. Este hallazgo pudiera deberse a una deficiencia en la ingesta materna de yodo

Hipertirotropinemia en recién nacidos mexicanos Hyperthyrotropinemia in Mexican newborns

OBJETIVO: Comunicar las diferencias encontradas en los niveles de concentración sanguínea de la hormona estimulante de la tiroides y su posible uso como indicador del estado de suficiencia de yodo en una muestra de recién nacidos mexicanos. MATERIAL Y MÉTODOS: De septiembre de 1999 a agosto de 2000 se estudiaron 25 427 recién nacidos en unidades asistenciales de la Secretaría de Salud de cinco estados de la República Mexicana. Se analizaron 8 095 muestras de sangre de talón y 17 332 de cordón umbilical. La sangre fue recolectada en papel filtro y procesada mediante ensayo inmunoenzimático. Para el análisis estadístico se emplearon las pruebas U de Mann-Wittney, y de Kruskal-Wallis. RESULTADOS: Se observó que 9.95% de las muestras de talón y 24.27% de las de cordón presentaron hipertirotropinemia (TSH>5 µUI/ml). CONCLUSIONES: El porcentaje de muestras de hipertirotropinemia observado es mayor del esperado para una población con aporte suficiente de yodo. Este hallazgo pudiera deberse a una deficiencia en la ingesta materna de yodo.OBJECTIVE: To assess the differences in the blood concentration levels of the thyroid stimulating hormone and their possible use as an indicator of iodine sufficiency, in a sample of Mexican newborns. MATERIAL AND METHODS: A cross-sectional study was conducted from September 1999 to August 2000, among 25,427 Mexican newborns in the Ministry of Health clinics from 5 states. A total of 8 095 heel-prick and 17 332 umbilical cord blood samples were analyzed. Blood samples were collected in filter paper and processed by enzyme-linked immunosorbent assay. The Mann-Whitney U test and the Kruskal-Wallis test were used for statistical analyses. RESULTS: Hyperthyrotropinemia was found in 9.95% of heel samples and in 24.27% of umbilical cord samples (TSH>5 µUI/ml). CONCLUSIONS: The percentage of hyperthyrotropinemia observed in this study was higher than that expected in a population with sufficient iodine intake; these findings could be due to poor maternal iodine intake