To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
While a clear human presence may be recognised in the Andes by 12 000–11 000 cal BP, most archaeological research has focused on occupation of the Andean highlands. To understand the initial occupation of inland areas of South America, the authors consider regional connections and spatial exploitation strategies of hunter-gatherers highlighted in a recent survey of Andean sites. Focusing on north-central Chile, artefacts and radiocarbon dates from three rock shelters suggest sporadic and brief occupation during the Terminal Pleistocene–Early Holocene. Co-occurrence of marine and montane resources, the authors argue, demonstrates a strategy of high mobility and local adaptation in early Andean occupation, using rock shelters as landmarks to navigate and learn new landscapes.
Putting a specific value on human life is important in many contexts and forms part of the basis for many political, administrative, commercial, and personal decisions. Sometimes, the value is set explicitly, sometimes even in monetary terms, but much more often, it is set implicitly through a decision that allows us to calculate the valuation of a life implicit in a certain rule or a certain resource allocation. We also value lives in what looks like a completely different way when we evaluate whether a particular life is being or has been lived well. Both of these ways of valuing are done from an outside or third-person perspective, but there is also a third way of valuing a life which is from the first-person perspective, and which essentially asks how much my life is worth to me. Is there any connection between these different ways of valuing life, and if so what is the connection between them? This paper provides an account of John Harris’ analysis of the value of life and discusses whether it can bridge the gap between first-person and third-person evaluations of the value of life, and whether it can do so in a way that still allows for resource allocation decisions to be made in health care and other sectors.
Embedding physical knowledge into neural network (NN) training has been a hot topic. However, when facing the complex real world, most of the existing methods still strongly rely on the quantity and quality of observation data. Furthermore, the NNs often struggle to converge when the solution to the real equation is very complex. Inspired by large eddy simulation in computational fluid dynamics, we propose an improved method based on filtering. We analysed the causes of the difficulties in physics-informed machine learning, and proposed a surrogate constraint (filtered partial differential equation, FPDE) of the original physical equations to reduce the influence of noisy and sparse observation data. In the noise and sparsity experiment, the proposed FPDE models (which are optimized by FPDE constraints) have better robustness than the conventional PDE models. Experiments demonstrate that the FPDE model can obtain the same quality solution with 100 % higher noise and 12 % quantity of observation data of the baseline. Besides, two groups of real measurement data are used to show the FPDE improvements in real cases. The final results show that the FPDE still gives more physically reasonable solutions when facing the incomplete equation problem and the extremely sparse and high-noise conditions. The proposed FPDE constraint is helpful for merging real-world experimental data into physics-informed training, and it works effectively in two real-world experiments: simulating cell movement in scratches and blood velocity in vessels.
This paper outlines the design of a six-element multiple-input–multiple-output (MIMO) antenna with pattern diversity for industrial scientific medical (ISM)/5G-enabled wireless body area networks (WBANs). Within the MIMO configuration, each element has a quasi-yagi antenna configuration implemented on an ultrathin microwave laminate. The proposed quasi-yagi antenna has a small form factor of 25 × 25 mm, featuring a dipole-like radiator excited through a microstrip-line to tapered slot-line transition. The antenna’s radiators are patterned to ensure a dual-narrow impedance bandwidth. The conventional strip-line director in the planar yagi is replaced with a semicircular loop-like director, enhancing directional radiation patterns. This proposed flexible antenna offers versatile functionality by operating at both ISM standards of 2.45 GHz and the 5G wireless local area network standard at 3.5 GHz. The quasi-yagi elements are strategically distributed in a hexagonal formation to construct the six-element MIMO scheme with pattern diversity, resulting in a tangential radiation pattern suitable for on-body communication. Following fabrication, the prototype MIMO antenna’s simulation results are validated through real-time measurements. The proposed antenna exhibits an average gain exceeding 3.5 dBi across both operating bands. Furthermore, the proposed MIMO antenna exhibits promising performance metrics suitable for densely cluttered WBAN environments.
We evaluated the viral load of varicella-zoster virus (VZV) in ambient air, vesicle, and pharyngeal swabs in VZV-infected patients. Of 46 cases, 6 had VZV detected in indoor air samples from patient rooms. Results suggest an association between viral load in the pharyngeal swab and indoor air.
We show that rotating Rayleigh–Bénard convection, where a rotating fluid is heated from below, exhibits a non-Hermitian topological invariant. Recently, Favier & Knobloch (J. Fluid Mech., vol. 895, 2020, R1) hypothesized that the robust sidewall modes in rapidly rotating convection are topologically protected. By considering a Berry curvature defined in the complex wavenumber space, we reveal that the bulk states can be characterized by a non-zero integer Chern number, implying a potential topological origin of the edge modes based on the Atiyah–Patodi–Singer index theorem (Fukaya et al., Phys. Rev. D, vol. 96 2017, 125004; Yu et al., Nucl. Phys. B, vol. 916, 2017, pp. 550–566). The linearized eigenvalue problem is intrinsically non-Hermitian, therefore, the definition of Berry curvature generalizes that of the stably stratified problem. Moreover, the three-dimensional set-up naturally regularizes the eigenvector, avoiding the compactification problem in shallow water waves (Tauber et al., J. Fluid Mech., vol. 868, 2019, R2). Under the hydrostatic approximation, it recovers a two-dimensional analogue of the one which explains the topological origin of the equatorial Kelvin and Yanai waves (Delplace et al., Science, vol. 358, issue 6366, 2017, pp. 1075–1077). The non-zero Chern number relies only on rotation when the fluid is stratified, no matter whether it is stable or unstable. However, the neutrally stratified system does not support a topological invariant. In addition, we define a winding number to visualize the topological nature of the fluid. Our results represent a step forward for the topologically protected states in convection, but the bulk-boundary correspondence requires a further direct analysis for proof, and the robustness of the edge states under varying boundary conditions remains a question to be answered.
Psychiatric comorbidity is common in children and adolescents with CHDs. Early recognition and evidence-based treatments are crucial to prevent long-term consequences. To support early identification and reduce stigma, we 1) developed and 2) tested the usability and acceptability of online information material on common mental health disorders targeted healthcare professionals and affected families. Website content was shaped by insights from interviews with healthcare professionals across sectors, parents, and adolescents. Evaluations demonstrated promising acceptability and usability of the first prototype but indicated the need for improvements in specific aspects of content, navigation, and overall aesthetics.
It is, perhaps, with some surprise that I find the native/non-native divide again attracting attention. The first I remember of this being an issue was when we were informed that the native speaker was dead (Paikeday, 1985). Needless to say, to those of us who did not feel at all deceased, this came as a surprise, but the announcement certainly attracted attention. The next contribution to the debate that I remember was Peter Medgyes's (1992) question regarding whether native or non-native was worth more. And so the dispute has continued spasmodically until the present, when we find two pieces on the subject within two recent issues of Language Teaching (Llurda & Calvet-Terré, 2024; Selvi et al., 2024).
Le fardeau administratif renvoie au phénomène selon lequel la mise en œuvre des politiques publiques et, plus généralement, les interactions avec l’État, sont coûteuses et difficiles. Chaque personne est en effet confrontée à des coûts d'apprentissage lorsqu'elle acquiert de l'information sur les programmes et services publics, à des coûts de conformité lorsqu'elle tente de satisfaire à leurs règles, et à des coûts psychologiques (stress, etc.) lorsqu'elle interagit avec ceux-ci. Cette littérature, presque exclusivement anglophone, s'est développée à un rythme effréné. Cette synthèse critique fait le bilan de ces récents développements et propose une discussion articulée autour de trois thèmes : 1) Que sont les fardeaux administratifs et quels enjeux soulèvent-ils? ; 2) Quelles sont les sources des fardeaux? ; et 3) Quelles en sont les conséquences distributives et politiques? Des pistes de recherche future sont proposées pour chacun de ces thèmes.
The aim of this study was to evaluate the rate of dysplasia and carcinoma-ex-papillomatosis in patients with recurrent respiratory papillomatosis and assess for any risk factors.
Methods
A 15-year retrospective observational cohort study was performed from a single centre. Data on patient demographics, treatment history and pathology results were extracted from clinical records.
Results
Of the 123 patients identified, nine had juvenile-onset recurrent respiratory papillomatosis and 114 had adult-onset recurrent respiratory papillomatosis. Thirteen (11 per cent) of patients with adult-onset recurrent respiratory papillomatosis had dysplasia, and one patient progressed to carcinoma-ex-papillomatosis. Patients with evidence of dysplasia had an average older age of disease onset compared to those without dysplasia (49 years vs 39 years, p = 0.03).
Conclusion
An older age of recurrent respiratory papillomatosis onset was the only risk factor for dysplasia. Gender, tobacco use, subglottic or tracheal involvement, number of surgeries and cidofovir were not prognostic factors in this series.
This article focuses on reducing mutual coupling between the ports of dielectric resonator antenna (DRA) using defected ground structures (DGSs). The antenna has the dimension of 50 mm × 50 mm × 8.5 mm. The resonating element in the proposed two-port radiator consists of a cylindrical structure of alumina ceramic (ɛr = 9.8). The rectangular-shaped aperture is utilized to excite both of the resonating elements. The resonating ceramic elements acting as radiators are offset-fed to enhance the antenna’s coupling. Combining interdigital-shaped and semicircular arc-shaped DGSs improves isolation between two resonating elements, embodying the structural novelty. The measured operating frequency range of Port-1 and Port-2 is 5.19–6.7 and 5.15–6.68 GHz, resonating at 5.58 and 5.56 GHz, respectively. The measured mutual coupling between the two ports is −35.5 dB. The measured gain for Port-1 is depicted to be 5.5 dB. The presented multiple-input–multiple-output (MIMO) radiator in this article is an appropriate candidate for WLAN (5.25–5.35, 5.47–5.725, 5.725–5.85, 5.850–5.925 GHz) and WiMAX(5.5 GHz) applications. All the simulated and experimentally observed MIMO parameters of the radiator are discovered to be within optimal bounds.
We prove several results concerning the existence of surfaces of section for the geodesic flows of closed orientable Riemannian surfaces. The surfaces of section $\Sigma $ that we construct are either Birkhoff sections, which means that they intersect every sufficiently long orbit segment of the geodesic flow, or at least they have some hyperbolic components in $\partial \Sigma $ as limit sets of the orbits of the geodesic flow that do not return to $\Sigma $. In order to prove these theorems, we provide a study of configurations of simple closed geodesics of closed orientable Riemannian surfaces, which may have independent interest. Our arguments are based on the curve shortening flow.
The world is currently undergoing a technological transformation with numerous innovative concepts emerging. This shift is driven by remarkable advancements in artificial intelligence and the urgent need for decarbonisation. With this comes a growing demand for skilled engineers who can actively contribute at any stage within the life cycle of a product. This can be the generation of new concepts at low Technology Readiness Levels or contributing actively to their development and operational safety. This paper explores the integration of a 1-day practical activity to reinforce theoretical concepts learned within a classroom-based environment. Small groups of students were given the opportunity of engaging with a small helicopter engine (Rolls-Royce Gnome engine) through the disassembly and reassembly of the exhaust and power turbine section while following the manufacturer’s manual and ensuring industrial norms for safe practice. This hands-on activity included an introduction to tooling, a Gnome familiarisation activity, and an introduction to inspection techniques. Based on the feedback recorded, the students experienced a notable improvement in their basic understanding by effectively reinforcing knowledge acquired within the classroom through active engagement with an actual gas turbine engine.
The COVID-19 pandemic created stressors to daily living, leading to increased mental health problems. It is important to assess the influence of COVID-19 pandemic on mental health, specifically anxiety.
Objectives
The goal was to determine the prevalence and sociodemographic, clinical, and other correlates of likely Generalized Anxiety Disorder (GAD) among study subjects in Ghana.
Design
This study employed a cross-sectional approach, using an online survey administered primarily through social media platforms. The survey questions included the GAD-7 scale, which was used to assess likely GAD in respondents. Data were analyzed using descriptive statistics, chi-square tests, and logistic regression analysis.
Participants
Overall, 756 respondents completed the survey, mainly from Ashanti and Greater Accra, which were the hardest hit by COVID-19.
Results
The prevalence of likely GAD in our sample was 7.6%. Gender, loss of job due to COVID-19, and seeking mental health counseling were independently associated with increased likelihood of GAD.
Conclusions
The findings suggest that women, those who lost their jobs due to the COVID-19 pandemic, and those who sought mental health counseling were more likely to experience moderate to high anxiety symptoms as a result of the COVID-19 pandemic. Priority must be attached to psychological support measures for members of these groups.
Complicated option pricing models attract much attention in financial industries, as they produce relatively better accurate values by taking into account more realistic assumptions such as market liquidity, uncertain volatility and so forth. We propose a new hybrid method to accurately explore the behaviour of the nonlinear pricing model in illiquid markets, which is important in financial risk management. Our method is based on the Newton iteration technique and the Fréchet derivative to linearize the model. The linearized equation is then discretized by a differential quadrature method in space and a quadratic trapezoid rule in time. It is observed through computations that the accurate solutions for the model emerge using very few grid points and time elements, compared with the finite difference method in the literature. Furthermore, this method also helps to avoid consideration of the convergence issues of the Newton approach applied to the nonlinear algebraic system containing many unknowns at each time step if an implicit method is used in time discretization. It is important to note that the Fréchet derivative supports to enhance the convergence order of the proposed iterative scheme.
Geothermal gradients and heterogeneous permeability are commonly observed in natural geological formations for underground CO$_2$ sequestration. In this study, we conduct three-dimensional direct numerical simulations on the double-diffusive convection with both unstable temperature and concentration gradients in homogeneous and heterogeneous porous media. For homogeneous porous media, the root-mean-squared velocity increases linearly with density ratio defined as the buoyancy ratio by temperature and concentration differences. The flow structures show no remarkable changes when temperature Rayleigh number ${Ra}_T$ is less than its critical value, but alter from sheet-like to cellular structures as ${Ra}_T$ surpasses this threshold. The concentration wavenumber scales approximately as $k_{rS}\sim {Ra}_e^{0.47}$ with a defined effective Rayleigh number ${Ra}_e$. By using a scale analysis, the concentration flux exhibits a consistent linear relation with the total driving forces for all simulations. For heterogeneous porous media, where the Dykstra–Parsons coefficient $V_{DP}$ and correlation length $l_{r}$ determine the spatial distribution of the permeability field, the flow is strengthened in places with higher permeability. The velocity and concentration flux are less affected by $l_{r}$ than that by $V_{DP}$. For small correlation length, the flow structures coarsen and their characteristic width generally increases with increasing heterogeneity. For large correlation length, small structures emerge in the regions with large permeability, which can be attributed to the intensified local Rayleigh number triggering more vigorous convection there. The variations of concentration flux with $l_{r}$ and $V_{DP}$ can be explained by the portion of area covered by high concentration with large vertical velocity near the boundaries.
Debate surrounds the early peopling of the Arabian Peninsula. The first evidence of the Levallois lithic technology in the Huqf area of south-eastern Arabia now extends the Middle Palaeolithic record of hominin activity into central Oman and helps to diversify the picture of Arabian prehistory.
The taxonomy of the subfamily Scolytinae has traditionally been based on external morphological attributes corresponding to the elytral declivity, head, and pronotum. Some traits from the general morphology of the aedeagus and spermatheca have been proposed in scarce genera. In this study, we explore and improve a technique of endophallus inflation to apply it in Scolytinae members and to describe its morphology for the first time in 16 species from Dendroctonus Erichson, Ips DeGeer, and Phloeosinus Chapuis. These taxa display differences in the attachment types of endophallus and two distinct inflation and retraction mechanisms. Our results support the use of the internal sac as a taxonomic feature in Scolytinae because each tribe, genus, and species display a particular morphological pattern. The results also indicate use of the internal sac for Dendroctonus taxonomy supports phylogenetic inferences.