Design and implementation in USRP of a preamble-based synchronizer for OFDM systems

The Orthogonal Frequency Division Multiplexing (OFDM) is one of the most widely adopted schemes in wireless technologies such as Wi-Fi and LTE due to its high transmission rates, and the robustness against Intersymbol Interference (ISI). However, OFDM is highly sensitive to synchronism errors, which affects the orthogonality of the carriers. We analyzed several synchronization algorithms based on the correlation of the preamble symbols through the implementation in Software-Defined Radio (SDR) using the Universal Software Radio Peripheral (USRP). Such an implementation was performed in three stages: frame detection, comparing the autocorrelation output and the average power of the received signal; time synchronism, where the cross-correlation based on the short and long preamble symbols was implemented; and the frequency synchronism, where the Carrier Frequency Offset (CFO) added by the channel was detected and corrected. The synchronizer performance was verified through the USRP implementation. The results serve as a practical guide to selecting the optimal synchronism scheme and show the versatility of the USRP to implement digital communication systems efficiently.Comment: 6 pages, to be presented at the ANDESCON - Biannual Technical and Scientific Conference of the Andean Council of the IEEE 202

Why hyperbolic theories of dissipation cannot be ignored: Comments on a paper by Kostadt and Liu

Contrary to what is asserted in a recent paper by Kostadt and Liu ("Causality and stability of the relativistic diffusion equation"), experiments can tell apart (and in fact do) hyperbolic theories from parabolic theories of dissipation. It is stressed that the existence of a non--negligible relaxation time does not imply for the system to be out of the hydrodynamic regime.Comment: 8 pages Latex, to appear in Phys.Rev.

Lessons from the operation of the "Penning-Fluorescent" TPC and prospects

We have recently reported the development of a new type of high-pressure Xenon time projection chamber operated with an ultra-low diffusion mixture and that simultaneously displays Penning effect and fluorescence in the near-visible region (300 nm). The concept, dubbed `Penning-Fluorescent' TPC, allows the simultaneous reconstruction of primary charge and scintillation with high topological and calorimetric fidelity

H(z)H(z) diagnostics on the nature of dark energy

The two dominant components of the cosmic budget today, pressureles matter and dark energy, may or may not be interacting with each other. Currently, both possibilities appear compatible with observational data. We propose several criteria based on the history of the Hubble factor that can help discern whether they are interacting and whether dark energy is phantom or quintessence in nature.Comment: 22 pages, 7 figures. Accepted for publication in IJMP

Association between Active Transportation and Public Transport with an Objectively Measured Meeting of Moderate-To-Vigorous Physical Activity and Daily Steps Guidelines in Adults by Sex from Eight Latin American Countries

This study aimed to examine the associations between active transportation and public transport and the objectively measured meeting of moderate-to-vigorous physical activity (MVPA) and steps per day guidelines in adults by sex from eight Latin American countries. As part of the Latin American Study of Nutrition and Health (ELANS), data were collected from 2524 participants aged 18–65 years. MVPA and steps per day were evaluated using Actigraph GT3X accelerometers. The mode of transportation, its frequency and duration were collected using a self-reported questionnaire. The average time dedicated to active transportation was 12.8 min/day in men (IQR: 2.8–30.0) and 12.9 min/day in women (IQR: 4.3–25.7). A logistic regression analysis was conducted, showing that active transportation (≥10 min) was associated with higher odds of meeting MVPA guidelines (men: OR: 2.01; 95%CI: 1.58–2.54; women: OR: 1.57; 95%CI: 1.25–1.96). These results show a greater association when considering active transportation plus public transport (men: OR: 2.98; 95%CI: 2.31–3.91; women: OR: 1.82; 95%CI: 1.45–2.29). Active transportation plus public transport was positively associated with meeting steps per day guidelines only in men (OR: 1.55; 95%CI: 1.15–2.10). This study supports the suggestion that active transportation plus public transport is significantly associated with meeting the MVPA and daily steps recommendations.Fieldwork and data analysis formulated in the ELANS protocol was supported by a scientific grant from the Coca Cola Company (2014/24168-6), and by grant and/or support from Instituto Pensi/Hospital Infantil Sabara, International Life Science Institute of Argentina, Universidad de Costa Rica, Pontificia Universidad Católica de Chile, Pontificia Universidad Javeriana, Universidad Central de Venezuela (CENDES-UCV)/Fundación Bengoa, Universidad San Francisco de Quito, and Instituto de Investigación Nutricional de Peru. The funding sponsors had no role in study design; the collection, analyses, or interpretation of data; writing of the manuscript; or in the decision to publish the results

Antibacterial Solution Using Cinnamomum verum (Cinammon) and Cympobogon citratus (Lemongrass) Essential Oils with Hydrogen Peroxide Against Staphylococcus aureus and Escherichia coli

Amidst the pandemic, millions of impoverished Filipinos lack sufficient access to sanitation services that protect them from bacterial infections. As such, this study endeavored to formulate a disinfectant spray of hydrogen peroxide and varying concentrations of lemongrass (Cymbopogon citratus) and cinnamon (Cinnamomum verum) essential oils to produce a maximally effective solution. Due to their natural origin, these essential oils were chosen for their extensive antibacterial properties, affordable price, and low toxicity levels. Six disinfectant spray solutions containing different concentrations of either essential oil were tested against Staphylococcus aureus and Escherichia coli bacteria through the agar disk diffusion method. After analyzing the data using mean, standard deviation, and MANOVA, it was found that including cinnamon and lemongrass essential oil had no statistically significant effect on the antibacterial activity of the hydrogen peroxide solution, regardless of the concentration of essential oil used, p \u3e 0.05. However, the lemongrass samples were slightly more effective than the cinnamon solutions. Thus, future researchers are encouraged to investigate other components that can potentially increase the antibacterial activity of a disinfectant spray

Interacting models may be key to solve the cosmic coincidence problem

It is argued that cosmological models that feature a flow of energy from dark energy to dark matter may solve the coincidence problem of late acceleration (i.e., "why the energy densities of both components are of the same order precisely today?"). However, much refined and abundant observational data of the redshift evolution of the Hubble factor are needed to ascertain whether they can do the job.Comment: 25 pages, 11 figures; accepted for publication in JCA

El impacto del embarazo en el desenlace de pancreatitis biliar aguda

Antecedentes y objetivo: La pancreatitis aguda es una de las condiciones gastrointestinalesmás comunes que requieren hospitalización. Aunque su aparición durante el embarazo es pococomún, representa un reto médico. Actualmente, no existen estudios que comparen los desen-laces clínicos entre mujeres embarazadas con pancreatitis aguda y pacientes no embarazadascon pancreatitis aguda. Nuestro objetivo fue comparar las características y desenlaces clínicosde las mujeres embarazadas y no embarazadas con pancreatitis aguda.Métodos: Realizamos un estudio retrospectivo que incluyó a todas las pacientes admitidas ennuestro hospital con pancreatitis aguda durante un periodo de 10 a˜nos. Se evaluaron y compa-raron los datos demográficos, las características generales y los desenlaces clínicos entre lasmujeres embarazadas y las mujeres no embarazadas con pancreatitis aguda, con una razón de1:5.Resultados: Se trató a 27 pacientes embarazadas con pancreatitis aguda en un periodo de10 a˜nos. La etiología fue biliar en el 96% de los casos y en el 3.4% de los casos la causa fuehipertrigliceridemia (un paciente). La edad media de las pacientes fue de 26.2 a˜nos (rango de15-36 a˜nos). La causa principal de la pancreatitis aguda fue la enfermedad biliar (96%). Laspacientes en el grupo de estudio cursaban su primer, segundo o tercer trimestre del embarazo,con una distribución del 7.4, el 33.3 y el 59.3%, respectivamente. En la comparación entrepacientes embarazadas y no embarazadas con pancreatitis aguda, no existieron diferencias enedad, tiempo de hospitalización (7.37 vs. 10.8, p = 0.814), gravedad (grave, 3.7% vs. 16.7%,p = 0.79), complicaciones locales (0% vs. 1.9%, p = 0.476) o mortalidad (0% vs. 1.9%, p = 0.476). Conclusiones: La evolución clínica de ambos grupos con pancreatitis biliar aguda fue similar,con baja morbimortalidad