Fourier series solution to the heat conduction equation with an internal heat source linearly dependent on temperature: Application to chilling of fruit and vegetables

This paper proposes a separation of variables solution to the equation for heat transfer by conduction in simply-shaped, homogeneous and isotropic bodies subjected to cooling or heating processes without a phase change and with an internal heat source that is a linear function of temperature and subject to homogeneous external conditions of the third kind. The solution is given by the sum of an infinite Fourier series. Starting from this solution, the paper also proposes a simple calculation of chilling time based on an approximation to the first term of that solution (exponential zone); it further proposes a first approximation to the maximum value attained by the temperature history, and to the corresponding time. © 2008 Elsevier Ltd. All rights reserved.Peer Reviewe

Photon to axion conversion during Big Bang Nucleosynthesis

We investigate how the resonant conversion at a temperature $\bar{T}=25$-$65$ keV of a fraction of the CMB photons into an axion-like majoron affects BBN. The scenario, that assumes the presence of a primordial magnetic field and the subsequent decay of the majorons into neutrinos at $T\approx 1$ eV, has been proposed to solve the $H_0$ tension. We find two main effects. First, since we lose photons to majorons at $\bar{T}$, the baryon to photon ratio is smaller at the beginning of BBN $(T>\bar{T})$ than during decoupling and structure formation ($T\ll \bar{T}$). This relaxes the $2\sigma$ mismatch between the observed deuterium abundance and the one predicted by the standard $\Lambda$CDM model. Second, since the conversion implies a sudden drop in the temperature of the CMB during the final phase of BBN, it interrupts the synthesis of lithium and beryllium and reduces their final abundance, possibly alleviating the lithium problem.Comment: 12 pages, 3 figures; new section added, matches version accepted by JCA

Pasiones de la filología

Este artículo propone una defensa de la filología que toma como punto de partida la relación entre el “amor al lenguaje” y el “amor al saber” en la cultura griega antigua. En la retórica psicagógica de Platón y en la lógica de Aristóteles la palabra es concebida como una forma de pathos, símbolo de las pasiones del alma o de las afecciones de la mente. Esta idea determina una larga tradición de filosofía del lenguaje que llega a la filología de época romántica e idealista, cuando Friedrich Schlegel proyecta una “Filosofía de la Filología” inspirada en el pensamiento kantiano, cuyos postulados fragmentarios han influido en algunas tendencias posteriores de los estudios filológicos y literarios. De esta moderna tradición de filología crítica (o filología filosófica) se deriva una nueva comprensión de las últimas teorías del lenguaje y la literatura, desde la deconstrucción de Jacques Derrida y Paul de Man hasta los recientes programas neofilológicos de Hans Ulrich Gumbrecht y Werner Hamacher.This article suggests an approach to philology that examines the relationships between “love of language” and “love of knowledge” in the cultural context of Ancient Greece. In accordance with Plato’s view of rhetoric as an art of “psychagogia” (soul-leading), and with Aristotle’s logic, words are conceived as symbols of the soul’s passions and the mind’s dispositional affects. These ideas have engendered an enduring tradition in the philosophy of language that extends to the philological program in Romantic Idealism, specifically Friedrich Schlegel’s project of a “philosophy of philology”, inspired by Kantian thought and its influence on subsequent methodologies and critical approaches in literary studies. Emerging from this modern tradition of critical philology is a new understanding of contemporary theories of language and literature, encompassing Jacques Derrida’s and Paul de Man’s Deconstruction, as well as the insights of Hans Ulrich Gumbrecht and Werner Hamacher

Cosmology of an Axion-Like Majoron

We propose a singlet majoron model that defines an inverse seesaw mechanism in the v sector. The majoron phi has a mass m(phi) approximate to 0.5 eV and a coupling to the tau lepton similar to the one to neutrinos. In the early universe it is initially in thermal equilibrium, then it decouples at T approximate to 500 GeV and contributes with just Delta N-eff = 0.026 during BBN. At T = 26 keV (final stages of BBN) a primordial magnetic field induces resonant gamma phi oscillations that transfer 6% of the photon energy into majorons, implying Delta N-eff = 0.55 and a 4.7% increase in the baryon to photon ratio. At T approximate to m(phi) the majoron enters in thermal contact with the heaviest neutrino and it finally decays into v (v) over bar pairs near recombination, setting Delta N-eff = 0.85. The boost in the expansion rate at later times may relax the Hubble tension (we obtain H-0 = (71.4 +/- 0.5) km/s/Mpc), while the processes v (v) over bar phi suppress the free streaming of these particles and make the model consistent with large scale structure observations. Its lifetime and the fact that it decays into neutrinos instead of photons lets this axion-like majoron avoid the strong bounds that affect other axion-like particles of similar mass and coupling to photons.We would like to thank Mar Bastero, Adrián Carmona, Mikael R. Chala, Miguel Escudero, Javier Olmedo, José Santiago and Samuel Witte for discussions. This work was partially supported by the Spanish Ministry of Science, Innovation and Universities (PID2019-107844GB-C21/AEI/10.13039/501100011033) and by the Junta de Andalucía (FQM 101, SOMM17/6104/UGR, P18-FR-1962, P18-FR-5057)

General relativistic effects of strong magnetic fields on the gravitational force: a driving engine for bursts of gamma rays in SGRs?

In general relativity all forms of energy contribute to gravity and not only just ordinary matter as in Newtonian Physics. This fact can be seen in the modified hydrostatic equilibrium equation for relativistic stars pervaded by magnetic (B) fields. It has an additional term coupled to the matter part as well as an anisotropic term which is purely of magnetic origin. That additional term coming from the pressure changed by the radial component of the diagonal electromagnetic field tensor, weakens the gravitational force when B is strong enough and can even produce an unexpected change in the attractive nature of the force by reversing its sign. In an extreme case, this new general relativistic (GR) effect can even trigger an instability in the star as a consequence of the sudden reversal of the hydrostatic pressure gradient. We suggest here that this GR effect may be the possible central engine driving the transient giant outbursts observed in Soft Gamma-ray Repeaters (SGRs). In small regions of the neutron star (NS), strong magnetic condensation can take place. Beyond a critical limit, these highly magnetised bubbles may explode releasing the trapped energy as a burst of gamma-rays of ~ 10^{36-40} erg.Comment: 6 pages, 2 figure

A user-centered chatbot to identify and interconnect individual, social and environmental risk factors related to overweight and obesity

[EN] The objective of this study was to assess the feasibility of using a user-centered chatbotfor collecting linked data to study overweight and obesity causes ina target population. In total 980 people participated in the feasibility study organized in three studies: (1) within a group of university students (88 participants), (2) in a small town (422 participants), and (3) within a university community (470 participants). We gathered self-reported data through the Wakamola chatbot regarding participants diet, physical activity, social network, living area, obesity-associated diseases, and sociodemographic data. For each study, we calculated the mean Body Mass Index (BMI) and number of people in each BMI level. Also, we defined and calculated scores (1-100 scale) regarding global health, BMI, alimentation, physical activity and social network. Moreover, we graphically represented obesity risk for living areas and the social network with nodes colored by BMI. Students group results: Mean BMI 21.37 (SD 2.57) (normal weight), 8 people underweight, 5 overweight, 0 obesity, global health status 78.21, alimentation 63.64, physical activity 65.08 and social 26.54, 3 areas with mean BMI level of obesity, 17 with overweight level. Small town ' s study results: Mean BMI 25.66 (SD 4.29) (overweight), 2 people underweight, 63 overweight, 26 obesity, global health status 69.42, alimentation 64.60, physical activity 60.61 and social 1.14, 1 area with mean BMI in normal weight; University ' s study results: Mean BMI 23.63 (SD 3.7) (normal weight), 22 people underweight, 86 overweight, 28 obesity, global health status 81.03, alimentation 81.84, physical activity 70.01 and social 1.47, 3 areas in obesity level, 19 in overweight level. Wakamola is a health care chatbot useful to collect relevant data from populations in the risk of overweight and obesity. Besides, the chatbot provides individual self-assessment of BMI and general status regarding the style of living. Moreover, Wakamola connects users in a social network to help the study of O & O ' s causes from an individual, social and socio-economic perspective.Funding for this study was provided by the authors' various departments, and partially by the Crowd Health Project (Collective Wisdom Driving Public Health Policies [727560]).Asensio-Cuesta, S.; Blanes-Selva, V.; Conejero, JA.; Portolés, M.; Garcia-Gomez, JM. (2022). A user-centered chatbot to identify and interconnect individual, social and environmental risk factors related to overweight and obesity. Informatics for Health and Social Care. 47(1):38-52. https://doi.org/10.1080/17538157.2021.1923501385247

Influence of hydrogen on the hydraulic fracture behavior of a 42CrMo4 steel welds: Effect of the prior austenite grain size

The influence of hydrogen on the mechanical behavior of a quenched and tempered 42CrMo4 steel has been evaluated by means of high internal pressure fracture tests carried out on hydrogen precharged notched cylindrical specimens. The notched cylindrical specimens were precharged in a 1 M H2SO4 + 0.25 g/l As2O3 solution for 3 h with 1.2 mA/cm2. Hydraulic fracture tests were performed at different loading rates. Hydrogen embrittlement resistance increased with grain size refinement although the fine grained specimen had a higher hydrogen content than the coarse grained one. Fractographic analysis showed hydrogen enhanced decohesion fracture was less pronounced with decreasing grain size. Hydrogen embrittlement susceptibility is discussed in terms of the prior austenite grain size (PAGS) and the operative fracture mechanisms.The authors would like to thank the Spanish Government for the financial support received to perform the research projects TED2021-130413B-I00 and PID2021-124768OB-C21. This work was supported by the Regional Government of Castilla y León (Junta de Castilla y León) and by the Ministry of Science and Innovation MICIN and the European Union Next Generation EU/PRTR (MR5W.P3) and PRTR (MR4W.P2). L.B. Peral is grateful for his Margarita Salas Postdoctoral contract (Ref.: MU-21-UP2021-030) funded by the University of Oviedo through the Next Generation European Union

Development of a novel scheme for long-term body temperature monitoring: a review of benefits and applications

Body temperature is a health or disease marker that has been in clinical use for centuries. The threshold currently applied to define fever, with small variations, is 38 °C. However, current approaches do not provide a full picture of the thermoregulation process and its correlation with disease. This paper describes a new non-invasive body temperature device that improves the understanding of the pathophysiology of diseases by integrating a variety of temperature data from different body locations. This device enables to gain a deeper insight into fever, endogenous rhythms, subject activity and ambient temperature to provide anticipatory and more efficient treatments. Its clinical use would be a big step in the overcoming of the anachronistic febrile/afebrile dichotomy and walking towards a system medicine approach to certain diseases. This device has already been used in some clinical applications successfully. 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