Universitat Rovira i Virgili

This chapter presents a wide range of practical applications for chipless RFID technology, showcasing its versatility across various industries, including healthcare, logistics, and environmental monitoring. Among others, the chapter highlights three key applications: chipless tags for material identification in the recycling chain, low-cost chipless time-temperature indicators (TTI) for temperature-sensitive good monitoring in the food supply chain, and chipless RFID tags for glucose sensing and diabetes screening. These examples demonstrate the potential of chipless RFID to address real-world challenges while offering cost-effective and scalable solutions.

This chapter explores and compares the figures of merit, key requirements, and primary topologies of wideband antennas within the context of chipless RFID tag readers. The chapter also examines the trade-offs and considerations when selecting antenna topologies for chipless RFID systems, offering insights into how these factors influence the overall system performance. Through a detailed comparison, the chapter provides an understanding of the role of wideband antennas in optimizing chipless RFID tag reader functionality.

This chapter presents the main types of chipless RFID tags, categorized by their coding principles. It covers the working principles, performance metrics, and examples of frequency-coded (FC), time-coded (TC), hybrid, image-based, motion-modulation, and near-field chipless tags. The chapter also discusses important figures of merit for tag design, such as radar cross section (RCS) and quality factor (Q), offering a detailed examination of these tag technologies.

This chapter proposes a signal processing implementation workflow for chipless RFID systems, covering the entire process from backscattered response preprocessing in various domains to feature extraction and decoding post-processing methods. Preprocessing involves a set of algorithms that transform the response between domains to facilitate the decoding process. The chapter explores the performance of several time-frequency transforms, including the short-time Fourier transform (STFT), continuous wavelet transform (CWT), Wigner-Ville distribution (WVD), and the smoothed pseudo-WVD (SPWVD), using measurements from frequency-coded tags under different conditions.

This chapter begins with a review of time gating, the most widely used signal post-processing algorithm for isolating the spectral content of chipless RFID tags from unwanted components in the backscattered response. It then examines common feature extraction and decoding techniques based on the singularity expansion method (SEM). The chapter concludes by exploring emerging approaches, such as machine learning (ML) algorithms or principal component analysis (PCA), that provide a more comprehensive analysis of backscattered chipless RFID tag responses.

This chapter presents a summary of the ultrawideband (UWB) emission guidelines established by the U.S. Federal Communications Commission (FCC), the European Telecommunications Standards Institute (ETSI), and the Electronic Communications Committee (ECC) for unlicensed spectrum usage below 10.6 GHz. Given that most chipless RFID tags are designed for operation within the 1–10.6 GHz range, it is crucial for readers intended for realistic applications to comply with these UWB emission standards. The chapter also discusses the regulation compliance of frequency-domain and time-domain chipless RFID tag readers, along with an analysis of their read-range performance under varying conditions.

This chapter explores the sensing capabilities of chipless RFID tags, highlighting their potential applications across various sensing domains. It begins with an overview of the transduction principles underlying chipless tags, followed by a discussion on the design of frequency-coded (FC) tags specifically tailored for sensing applications. The chapter also covers various methods for analyzing and interpreting the signals generated by chipless tags in different sensing scenarios. To illustrate these concepts, the chapter concludes with several examples of chipless RFID sensors in practical applications, showcasing their versatility and effectiveness in real-world.

Des-Cubierta Cave, part of the Calvero de la Higuera complex, is situated in the intramountainous upper valley of the Lozoya River within the Guadarrama Range. The cave's geological, palaeontological, and archaeological record reveals a complex history of sedimentary and anthropogenic processes spanning hundreds of thousands of years, represented in 12 lithostratigraphic units. Among these, Unit 3 stands out for its archaeological significance, containing evidence of Neanderthal activity, including Mousterian lithic tools and an unusual assemblage of large mammal crania, which suggests symbolic behaviour. Geological data indicate that Unit 3 was deposited during cold periods (MIS 4) through multiple rockfall episodes, implying that these symbolic practices persisted across generations. The cave's geomorphology points to a possible Neanderthal entrance via a side opening created by erosion in the southern part of the cave. This study enhances our understanding of Des-Cubierta Cave's geological development and the long-term Neanderthal occupations, offering valuable insights into their symbolic and cultural behaviours.

Developing efficient heterogeneous Fenton-like materials is crucial for widespread implementation as it addresses technical challenges associated with conventional Fenton processes. These challenges include the need for large quantities of homogeneous catalysts and resulting secondary pollution from added catalytic species and their oxides. This paper describes the synthesis of a highly effective NiCuAl-HT compound. The compound serves as a Fenton-like catalyst when combined with H2O2 to oxidize organic contaminants in a simulated synthetic wastewater from oil refineries ‘SPRW’. The catalyst was calcined at different temperatures (180°C, 320°C, and 870°C) to evaluate and compare its performance with that of the non-calcined catalyst. Calcination of the NiCuAl-HT material, formed by achieving high supersaturation with the molar ratio R: (Ni2++Cu2+)/Al3+ equal to 2.0 and the molar ratio Ni2+/Cu2+ equal to 1.0, leads to the formation of nanometric oxides. The non-calcined sample exhibited superior performance for SPRW oxidation, as revealed by comparative analysis. The NiCuAl-HT/H2O2 system achieved almost complete mineralization, as shown by TOC analysis, with a 65.24% removal efficiency after 90 min, the other systems where the material is calcined at 380°C and 870°C, TOC removal was 47.80% and 06.67%, respectively, setting all parameters at: H2O2/COD: 5, mcat: 0.4 g L−1, T: 60°C, and pH: pHPZC. The efficiency of the catalytic reaction can be attributed to the layered structure of HT and the inclusion of hydroxyl groups on the brucite sheets.

Mobile dating apps (MDA) are popular for intimate encounters, but romantic rejection is common, and can drive surveillance using information from social media. Awareness cues convey digital information about others’ activities, but their link with rejection is underexplored. This study explores the uses of awareness cues in mobile dating applications (MDAs) in relation to rejection, social surveillance and post-digital safety. Using a 1-month diary study with eight participants of diverse gender and sexual identities, we identify a grammar of awareness cues that helps users interpret others’ intentions, manage relational uncertainty (e.g. ghosting) and navigate rejection. While awareness cues convey helpful information, they also expose users to social surveillance or even stalking. Since ‘incognito mode’ is a premium affordance on most MDAs, participants developed creative invisibility strategies to restrict access to social surveillance mechanisms.

Chemometric models play a critical role in the spectroscopic analysis of food, particularly with near‐infrared spectroscopy (NIRS), enabling the accurate prediction and monitoring of physicochemical properties. Although chemometric methods have proven to be useful tools in NIRS analysis, their reliability depends on rigorous validation to ensure the rigour of their predictions and their applicability. This systematic review examines validation strategies applied to regression models in NIRS‐based food analysis, emphasising the use of cross‐validation, external validation and figures of merit (FoM) as key evaluation tools. This comprehensive literature search identified trends in validation methodologies, highlighting frequent reliance on partial least squares (PLS) regression and common flaws in validation methodologies and their reporting. While external validation is considered the best approach, many studies lack it and employ cross‐validation methods solely, which may lead to overoptimistic model performance estimates. Furthermore, inconsistencies in the selection and definition of FoM hinder direct comparison across studies. This review underscores the need for increased methodological transparency and rigour in the validation of chemometric models to enhance their reliability.

People organize in groups and contagions spread across them. A simple stochastic process, yet complex to model due to dynamical correlations within and between groups. Moreover, groups can evolve if agents join or leave in response to contagions. To address the lack of analytical models that account for dynamical correlations and adaptation in groups, we introduce the method of generalized approximate master equations. We first analyze how nonlinear contagions differ when driven by group-level or individual-level dynamics. We then study the characteristic levels of group activity that best describe the stochastic process and that optimize agents’ ability to adapt to it. Naturally lending itself to study adaptive hypergraphs, our method reveals how group structure unlocks new dynamical regimes and enables distinct suitable adaptation strategies. Our approach offers a highly accurate model of binary-state dynamics on hypergraphs, advances our understanding of contagion processes, and opens the study of adaptive group-structured systems.

The present erratum is intended to correct some typos in our paper [J. Opt. Soc. Am. A 39, 1774 (2022)JOAOD60740-323210.1364/JOSAA.466318].

Metapopulation models have traditionally assessed epidemic dynamics by emphasizing local (in situ) interactions within defined subpopulations, often neglecting transmission occurring during mobility phases (in itinere). Here, we extend the Movement–Interaction–Return metapopulation framework to explicitly include contagions acquired during transit, considering agents traveling along shared transportation networks. We reveal that incorporating in itinere contagion entails a notable reduction of the epidemic threshold and a pronounced delocalization of the epidemic trajectory, particularly significant in early-stage outbreaks.

The consolidation of scientific knowledge is based on the accumulation and understanding of previous findings. Nowadays, reviews of the scientific literature have become more effective through the use of meta-analyses, which are systematic evaluations of the results from multiple studies. Similarly, mega-analyses, which combine raw data from many studies into a single sample for processing and statistical analysis, are a very powerful tool for analyzing results of heterogeneous origin but require a high level of collaboration between the researchers contributing data. In the framework of a collaborative methodology between different Spanish viticultural research groups, this work uses a mega-analytical approach to quantify the effects of changes in vine water status on vine vegetative growth, yield, and grape composition, integrating a wide range of growing conditions to obtain robust general trends of vine performance under water deficit. The mean seasonal stem water potential data from the different studies allowed a classification into five levels of water status (no deficit ⟶ mild ⟶ moderate ⟶ high ⟶ severe). A progressive decrease in vegetative growth with increasing deficit was observed, while yield decreased more markedly as water deficit progressed from moderate to high. On the other hand, titratable acidity was more sensitive to variation in water status than sugar concentration, with a greater decrease in titratable acidity when changing from no to moderate deficit. Conversely, increasing water deficit from moderate to high resulted in the greatest increases in grape anthocyanin in the red varieties explored. The results obtained in this work provide solid information on general trends in grapevine response to water deficit that can be used in simulation models or incorporated by grape growers in their decision-making processes in relation not only to irrigation management but also on other agronomic tools to impact grapevine water status.

Intelligent soft matter lies at the intersection of materials science, physics, and cognitive science, promising to change how we design and interact with materials. This transformative field aims to create...

This conceptual chapter delves into the transformative impact of hybrid work models on environmental sustainability in the post-COVID-19 period of transformed knowledge work and hybridized places of work. It narratively examines and debates how the integration of in-office and remote work can significantly reduce energy consumption and carbon emissions. The focus is twofold: first, on the reduction of office resource needs, including energy demands for heating, cooling, and lighting in commercial spaces; second, on the substantial decrease in commuting requirements, leading to lower traffic congestion and reduced urban pollution. The chapter further explores the potential of hybrid workplaces to inspire employees toward more sustainable lifestyles, influencing both urban planning and personal transportation choices. Crucially, it discusses the need for strategic implementation of these models, emphasizing the roles of technological integration, efficient home-office setups, and balanced scheduling to optimize environmental benefits. Finally, the chapter concludes that effectively managed hybrid work environments align with contemporary workforce expectations and represent a pivotal advancement toward sustainable, post-pandemic workplaces.

The first 1000 days of life are crucial for health, making it essential that foods for infants and young children (FIYC) meet high nutritional standards, as defined by the World Health Organization's (WHO) Nutrient and Promotion Profile Model (NPPM). There is high reliance on commercially available highly processed FIYC for children under 3 years of age, and a growing market. The aim of this study is to analyse the nutrient profiles of FIYC using the WHO NPPM and determine the proportion of products available in Spain suitable for promotion. Data on 830 FIYC available from brands sold by major retailers in Spain were collected. Product nutrient composition and label information were assessed using the WHO NPPM for the European Region. The processed fruit and vegetables were the most common FIYC category, accounting for 46% of the products surveyed. Overall, only 23% met all NPPM nutritional standards. About 60% of products had excessive sugar content, with 98% of fruit and vegetable purees qualifying for a front-of-pack sugar warning. One in four savoury meals was protein-deficient and one in four of all FIYC was energy-deficient. Only 7% and 2% exceeded the sodium and fat limits, respectively. No product fully met the NPPM promotion recommendations. Conclusion: Nearly 80% of FIYC products in Spain do not meet WHO’s NPPM criteria for nutrient quality, with many high in sugar, low in protein and too watery (low energy). None met the promotional recommendations, highlighting the need for better regulation to improve the nutritional content and appropriate marketing of products for young children. What is Known? • The first 1,000 days of life are critical for child development and require optimal nutrition. • The WHO European Region developed the Nutrient and Promotion Profile Model (NPPM) to evaluate foods for infants and young children (FIYC). What is New? • This is the first comprehensive study applying the WHO NPPM to 830 FIYC products on the Spanish market. • Nearly 80% of products failed to meet the nutritional standards, and none complied with the promotion criteria.