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Following the groundbreaking discovery of the ferroelectric nematic liquid crystal phase (N_{F}), a series of closely-related new polar phases have also been found. An especially interesting one is the ferroelectric smectic A phase (SmA_{F}) with spontaneous polarization along the layer normal observed in a few materials of the N_{F} realm. Here, we present a mean-field molecular model that successfully captures the rich phase diagrams experimentally observed in the literature in terms of two parameters. Additionally, we carry out second harmonic generation, X-ray diffraction, and birefringence measurements in a compound exhibiting the SmA_{F} phase to determine the appropriate order parameters and compare with the model predictions.

Ferroelectric nematic liquid crystals are currently being subject to a plethora of investigations since they are of great fundamental interest and could potentially foster promising applications. However, many basic aspects are still poorly understood, among which the problem of the dielectric constant stands out. Ferroelectric nematics have previously been reported to exhibit giant dielectric constants whose value depends on the thickness of the measurement cell, claims that have recently been shown to be the result of an incorrect interpretation of the experimental data. The intrinsic permittivity of these materials has not been determined yet. In this work, we tackle this problem by modeling the dielectric response of the liquid crystal filled cell through an equivalent circuit proposed by Clark et al. [Phys. Rev. Res. 6, 013195 (2024)2643-156410.1103/PhysRevResearch.6.013195] accounting for polarization reorientation and the effect of insulating interfacial layers. We arrive at the conclusion that the perpendicular component of the permittivity ɛ_{⊥} is of the order of 10 in the prototypical ferroelectric nematogen DIO, while the parallel component ɛ_{∥} is of the order of 150. In this way, the dielectric tensor of DIO has been fully determined.

A simple and novel setup for high-frequency dielectric spectroscopy of materials has been developed using a portable vector network analyzer. The measurement principle is based on radio frequency reflectometry, and both its capabilities and limitations are discussed. The results obtained on a typical liquid crystal prove that the device can provide reliable spectra between 107 and 109 Hz, thus extending the capabilities of conventional impedance analyzers., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

A great deal of effort has been recently devoted to the study of dielectric relaxation processes in ferroelectric nematic liquid crystals, yet their interpretation remains unclear. In this work, we present the results of broadband dielectric spectroscopy experiments of a prototypical ferroelectric nematogen in the frequency range 10 Hz-110 MHz at different electrode separations and under the application of DC bias fields. The results evidence a complex behavior in all phases due to the magnitude of polar correlations in these systems. The observed modes have been assigned to different relaxation mechanisms based on existing theoretical frameworks., (© 2023 Author(s). Published under an exclusive license by AIP Publishing.)

Using new and original nineteenth-century sources, we analysed the epidemiology, clinical features and virology of the 1889 pandemic, which was referred to at the time as 'Russian flu' or 'Asiatic flu'. However, we rejected this identification of the disease as an 'influenza', which we believe to have been based on insufficient knowledge of the causative agent and instead posit that the pandemic was caused by a coronavirus. We provide a new account of the 1889-1893 pandemic, with a more detailed chronology that included at least four epidemiological waves. At the end of 1889, a new virus appeared in Europe, which could be identified as the coronavirus HCoV-OC43, causing crude death rates of 1.3 per 1000 population in St Petersburg; 2.1 per 1000 in Paris; 2.8 per 1000 in Bilbao and on the French-Spanish border; between 2.9 and 5.2 per 1000 in small towns in the Basque Country; and 5.8 deaths per 1000 in Madrid, which had the highest death rate. The clinical features of the disease differed from classical influenza pandemics in terms of the latency phase, duration, symptomatology, convalescence, immunity, age and death rates. Another factor to be considered was the neurotropic capacity of the disease. The most frequent form of the 1889 pandemic was the 'nervous form', with specific symptoms such as 'heavy headache' ( céphalalgie gravative ), tiredness, fever and delirium. There are strong parallels between the 1889-1894 pandemic and the COVID-19 pandemic, and a better understanding of the former may therefore help us to better manage the latter.

The 1918-1919 influenza pandemic had a significantly different impact on mortality rates in Spanish and Portuguese provinces and cities. In this study, several small villages have been identified which were not affected at all by the Spanish influenza pandemic. These all shared a number of features in common: their villages were very small, comprising only a few hundred inhabitants; they were located in mountainous regions, with very poor transport infrastructure; and they were self-sufficient and capable of fulfilling their basic alimentary needs. Their inhabitants were conscious of the problem and acted together, effectively isolating themselves from surrounding villages. Since these villagers managed to avoid direct contact with ill people from other municipalities, the flu was not transmitted and the pandemic did not arise in their villages. In this paper, it is proposed that the human habitability spaces that meet these characteristics, I call them "Safe Villages" or "Shelter Village". Knowledge of the circumstances in which the 1918-1919 flu pandemic developed and of the means employed to resist it can help us to take relevant measures when faced with future pandemics., Competing Interests: Conflict of interest statement The author declares no conflict of interest., (©2020 Pacini Editore SRL, Pisa, Italy.)

Computer vision is used in this work to detect lighting elements in buildings with the goal of improving the accuracy of previous methods to provide a precise inventory of the location and state of lamps. Using the framework developed in our previous works, we introduce two new modifications to enhance the system: first, a constraint on the orientation of the detected poses in the optimization methods for both the initial and the refined estimates based on the geometric information of the building information modelling (BIM) model; second, an additional reprojection error filtering step to discard the erroneous poses introduced with the orientation restrictions, keeping the identification and localization errors low while greatly increasing the number of detections. These enhancements are tested in five different case studies with more than 30,000 images, with results showing improvements in the number of detections, the percentage of correct model and state identifications, and the distance between detections and reference positions.

The present article investigates the question of building energy monitoring systems used for data collection to estimate the Heat Loss Coefficient (HLC) with existing methods, in order to determine the Thermal Envelope Performance (TEP) of a building. The data requirements of HLC estimation methods are related to commonly used methods for fault detection, calibration, and supervision of energy monitoring systems in buildings. Based on an extended review of experimental tests to estimate the HLC undertaken since 1978, qualitative and quantitative analyses of the Monitoring and Controlling System (MCS) specifications have been carried out. The results show that no Fault Detection and Diagnosis (FDD) methods have been implemented in the reviewed literature. Furthermore, it was not possible to identify a trend of technology type used in sensors, hardware, software, and communication protocols, because a high percentage of the reviewed experimental tests do not specify the model, technical characteristics, or selection criteria of the implemented MCSs. Although most actual Building Automation Systems (BAS) may measure the required parameters, further research is still needed to ensure that these data are accurate enough to rigorously apply HLC estimation methods.

Background: The impact of socio-demographic factors and baseline health on the mortality burden of seasonal and pandemic influenza remains debated. Here we analyzed the spatial-temporal mortality patterns of the 1918 influenza pandemic in Spain, one of the countries of Europe that experienced the highest mortality burden., Methods: We analyzed monthly death rates from respiratory diseases and all-causes across 49 provinces of Spain, including the Canary and Balearic Islands, during the period January-1915 to June-1919. We estimated the influenza-related excess death rates and risk of death relative to baseline mortality by pandemic wave and province. We then explored the association between pandemic excess mortality rates and health and socio-demographic factors, which included population size and age structure, population density, infant mortality rates, baseline death rates, and urbanization., Results: Our analysis revealed high geographic heterogeneity in pandemic mortality impact. We identified 3 pandemic waves of varying timing and intensity covering the period from Jan-1918 to Jun-1919, with the highest pandemic-related excess mortality rates occurring during the months of October-November 1918 across all Spanish provinces. Cumulative excess mortality rates followed a south-north gradient after controlling for demographic factors, with the North experiencing highest excess mortality rates. A model that included latitude, population density, and the proportion of children living in provinces explained about 40% of the geographic variability in cumulative excess death rates during 1918-19, but different factors explained mortality variation in each wave., Conclusions: A substantial fraction of the variability in excess mortality rates across Spanish provinces remained unexplained, which suggests that other unidentified factors such as comorbidities, climate and background immunity may have affected the 1918-19 pandemic mortality rates. Further archeo-epidemiological research should concentrate on identifying settings with combined availability of local historical mortality records and information on the prevalence of underlying risk factors, or patient-level clinical data, to further clarify the drivers of 1918 pandemic influenza mortality.

Background: Studies of the Spanish Influenza pandemic (1918-1920) provide interesting information that may improve our preparation for present and future influenza pandemic threats., Methods: We studied archives from France, Italy, Spain and Portugal, obtaining high-quality data that allowed us to calculate mortality rates associated with the Spanish flu and to characterize the proportional distribution of influenza deaths by age in the capital cities of these countries., Results: French and American troops who fought in the First World War began to be affected from April 1918 onwards by a benign influenza epidemic, which hardly caused any deaths. The first occidental European country in which the pandemic spread to large sectors of the population, causing serious mortality, was Spain. The associated influenza provoked in Madrid a mortality rate of 1.31 per 1000 inhabitants between May and June (1918). In the following months of June and July, the epidemic spread to Portugal, but did not reach the Pyrenees. In September 1918, the influenza pandemic spread with tremendous virulence, presenting itself simultaneously during the month of October in South Western European countries. In Madrid, the 1918 excess mortality due in large part to the influenza pandemic is estimated at 5.27 per 1000. In Paris, the 1918 mortality rate provoked by the influenza and pathologies of the respiratory system was 6.08 per 1000. In South Western European countries, mortality rates oscillated between 10.6 and 12.1 per 1000 inhabitants. A study of the age distribution of deaths due to influenza between 1916 and 1921 reveals that the Spanish influenza principally affected men and women between 15 and 44 years of age. Deaths associated with the seasonal influenza of 1916, 1917 and 1921 represented 19.7%, 12.5% and 21.0% of all deaths respectively, whereas during the rawest moments of the Spanish influenza, in 1918, the proportion of deaths due to flu for those aged between 15 and 44 years of age reached 68.2% in Paris and 66.3% in Madrid., Conclusion: Victim age is an important criterion that can be used to evaluate the phase and evolution of pandemic influenza. The Spanish Influenza affected particularly the 25- to 34-year-old and 15- to 24-year-old age groups.

The virus which was responsible for the first benign wave of the Spanish Influenza in the spring of 1918, and which was to become extremely virulent by the end of the summer of 1918, was inextricably associated with the soldiers who fought during the First World War. The millions of young men who occupied the military camps and trenches were the substrate on which the influenza virus developed and expanded. Many factors contributed to it, such as: the mixing on French soil of soldiers and workers from the five continents, the very poor quality of life of the soldiers, agglomeration, stress, fear, war gasses used for the first time in history in a massive and indiscriminate manner, life exposed to the elements, cold weather, humidity and contact with birds, pigs and other animals, both wild and domestic. Today, this combination of circumstances is not present and so it seems unlikely that new pandemics, such as those associated with the avian influenza or swine influenza, will emerge with the virulence which characterized the Spanish Influenza during the autumn of 1918.

The Basque Museum of the History of Medicine was founded in 1982 to preserve the historic memory of medicine in the Basque Country and conserve its scientific heritage. Its permanent exposition comprises approx. 6,000 medical objects of the 19th and 20th centuries arranged, thematically in 24 rooms devoted to different medical specialities: folk medicine, unconventional medicine, pharmacy, weights and measures, asepsis and antisepsis, microscopes, laboratory material, X-rays, obstetrics and gynaecology, surgery, anesthesia, endoscope, odontology, cardiology, ophthalmology, electrotherapy, pathological anatomy and natural sciences. Temporary exhibitions are also held. The Museum is located on the university campus (UPV/EHU) and is important in the training of students in the Faculty of Medicine and the students coming from other faculties. Teaching and research constitute two of the pillars of the Museum that are complemented with publications and the organization of conferences, lectures and other activities.

The paper studies the great epidemics that have affected Europe from the middle ages until the 20th century. A special emphasis is put on in the mortality of the Black Death in 1348 (500 per thousand), the smallpox in the 18th century (150 per thousand), the spotted fever in the end of the 18th century (50 per thousand), the cholera pandemic in the 19th century (25.5 - 62.7 per thousand), the tuberculosis in the end of the 19th century (5.3 per thousand) and the mortality that the Spanish influenza produced in the beginnings of the 20th century (12.1 per thousand) in the Basque Country.

This article presents calculations and comparisons of mortality rates for influenza, for diseases of the respiratory system (with the exception of tuberculosis) and for all the causes of death, in 21 locations in the Basque Country (between Spain and France). The data were collected from all the entries in the death registers for the period between May 1918 and April 1919. The Spanish influenza pandemic affected this population sample to a varying extent. Depending on the characteristic of the different locations, the mortality rate varied between 2.2 and 19.7 per thousand for influenza, and between 7.5 and 25.7 per thousand for influenza and other diseases of the respiratory system. The mortality rate for the total population studied has been calculated to be 6.8 per thousand for Spanish influenza and 12.1 per thousand for influenza and other diseases of the respiratory system. The first wave of the pandemic (spring 1918) was benign like a seasonal influenza. The second wave (autumn 1918) was extremely virulent owing to the mutation of the virus in Europe during the summer. This article identifies one of the sites, on the border between France and Spain, from which the second wave of the Spanish flu spread.