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Given a nonzero integer n, Gupta and Saha [‘Integer solutions of the generalised polynomial Pell equations and their finiteness: the quadratic case’, Canad. Math. Bull., to appear] classified all polynomials $x^2+ax+b\in {\mathbb {Z}}[x]$ for which the polynomial Pell equation $P^2-(x^2+ax+b)Q^2=n$ has solutions ${P,Q\in {\mathbb {Z}}[x]}$ with $Q\neq 0$. We generalise their work to the equation $P^2-(f^2+af+b)Q^2=nR$, where f is a fixed polynomial in ${\mathbb {Z}}[x]$. As an application of our results, we study the equation $P^2-D(f)Q^2=n$, where D is a monic, quartic and non square-free polynomial in ${\mathbb {Z}}[x]$. This extends Theorem 1.4 of Scherr and Thompson [‘Quartic integral polynomial Pell equations’, J. Number Theory259 (2024), 38–56].
Between 2023 – 2024, 60 infections (urinary tract, n = 31; skin/soft tissue, n = 18; pneumonia, n = 7; influenza-like illness, n = 5) were diagnosed by home-based primary care clinicians from one site, including 35% through telehealth. 43% met standardized surveillance definitions. Most antibiotic prescriptions (n = 27/48) involved durations ≥7 days. Additional studies of home care infections are needed.
This article assesses a 10-month co-created universal school-based mental health (SBMH) promotion initiative for adolescents (10–19). The study combined quantitative and qualitative components. Pre- and post-intervention surveys were conducted in four schools in Tanzania (n = 400 baseline, 488 endline, with 100 intervention participants at both) and eight schools in Vietnam (n = 1,036 baseline, 893 endline and 436 in panel). In each country, ~90 qualitative interactions (interviews and focus groups) were held at baseline and endline with adolescents, parents, teachers and service providers (total = ~180). In Tanzania, multivariate analysis indicated significant gains among intervention participants relative to peers. Emotional literacy rose 9.5% (p = 0.007; d = 0.57). Attitudes toward help-seeking (p = 0.021; d = 0.50) and prosocial behaviors (p = 0.043, d = 0.38) also improved Active coping increased 15.6% (p = 0.006; d = 0.55). In Vietnam, emotional literacy increased 5.3% (p = 0.012, η2 = .019), and positively, emotion-focused coping declined 14.4% (p = 0.032, η2 = .015). Qualitative evidence reinforces these findings, and suggested spillover effects for nonparticipants. Overall results indicate that co-created universal SBMH initiatives can improve adolescent well-being and offer viable alternatives to limited adolescent-focused mental health services in LMICs.
Let $G = X \wr H$ be the wreath product of a nontrivial finite group X with k conjugacy classes and a transitive permutation group H of degree n acting on the set of n direct factors of Xn. If H is semiprimitive, then $k(G) \leq k^n$ for every sufficiently large n or k. This result solves a case of the non-coprime k(GV) problem and provides an affirmative answer to a question of Garzoni and Gill for semiprimitive permutation groups. The proof does not require the classification of finite simple groups.
Verification of the coincidence between the radiation and mechanical isocentres is an essential quality assurance (QA) procedure for linear accelerators (linacs) in radiotherapy. Ensuring this alignment is critical for accurate beam targeting, especially in conformal and intensity-modulated radiotherapy techniques.
Objective:
This study aimed to evaluate the feasibility and effectiveness of using computed radiography (CR) with a bare imaging plate (IP) to assess the coincidence between radiation and mechanical isocentres, as a practical QA method, especially applicable in resource-limited settings.
Materials and Methods:
The study was conducted on a Precise linac installed at Bac Ninh General Hospital No2. A Fujifilm IP and an FCR Prima T2 reader were used. Mechanical isocentre marking was performed via 1 monitor unit (MU) open-field exposure. Radiation isocentre verification involved multiple exposures with narrow rectangular fields at various gantry, collimator and couch angles. The latent images were processed using FCR View software to analyse displacement diameters between mechanical and radiation centres.
Results:
The CR system demonstrated sufficient sensitivity to detect exposures as low as 1 MU. Deviations (diameters) were 0·44–1·04 mm with expanded uncertainty U up to 0·44 mm (k = 2). All measurements were within the ±2 mm tolerance recommended by American Association of Physicists in Medicine (AAPM) for non-stereotactic systems.
Conclusion:
The use of a bare IP in CR offers a reliable and low-cost alternative for verifying the coincidence of radiation and mechanical isocentres. This method is suitable for routine QA procedures in clinical environments lacking access to radiochromic film or electronic portal imaging devices.
We sought to identify risk factors for coagulase-negative staphylococcal (CoNS) surgical site infection (SSI). Risk factors associated with an increased risk of CoNS SSI include male sex and asthma or COPD. Colon surgery was associated with a reduced risk of CoNS SSI.
The descent method is one of the approaches to study the Brauer–Manin obstruction to the local–global principle and to weak approximation on varieties over number fields, by reducing the problem to ‘descent varieties’. In recent lecture notes by Wittenberg, he formulated a ‘descent conjecture’ for torsors under linear algebraic groups. The present article gives a proof of this conjecture in the case of connected groups, generalizing the toric case from the previous work of Harpaz–Wittenberg. As an application, we deduce directly from Sansuc’s work the theorem of Borovoi for homogeneous spaces of connected linear algebraic groups with connected stabilizers. We are also able to reduce the general case to the case of finite (étale) torsors. When the set of rational points is replaced by the Chow group of zero-cycles, an analogue of the above conjecture for arbitrary linear algebraic groups is proved.
This chapter connects the French introduction of fast-growing, exotic hard timber species in Vietnam to the intensive search for mine timber to support the coal mining industry. The filao tree known scientifically as Casuarina equisetifolia, and the eucalyptus were introduced in Vietnam by the French in 1896 for the dual purpose of harvesting their hard timber for mine props and using them to reforest the shifting sand dunes along the coast of Annam, a French protectorate in what is now central Vietnam. Through a long and complex process of growing and acclimating the trees to Annam’s coastal sand dunes, French foresters were able to successfully grow the filao in industrial-style plantations and nurseries. Their success helped establish the filao as a popular exotic hard timber species for the reforestation of coastal sand dunes, not just in Vietnam but also in other French colonies, such as Senegal and Madagascar. Overall, the stories of the filao shed light on transnational connections between coal mining and the environment during the age of the empire, when the mining-driven search for hard timber commodities transformed the landscapes of both Vietnam and Africa.
Drawing from ca dao vùng mỏ (the lesser-known writings of anonymous Vietnamese miners), the vibrant Vietnamese print press of the 1930s, and other archival sources, this chapter offers insights into the internal workings of large-scale coal mining enterprises, which were founded on racial, professional, and gendered power structures. In addition, this chapter describes the formation of a strong oppositional and distinctive Vietnamese miner subculture, forged both within and beyond the mines. Outside the mines, far from company surveillance, miners engaged in collective acts, such as theft, fraud, and illicit recreational activities, such as opium smoking, gambling, and smuggling, to supplement their wage income or to simply decompress after a hard day at work in the company of their workmates. The relative autonomy and strength of this miner subculture reveal the failure of the internal working regime of coal mining companies to impose uniform working patterns on their employees. Instead, workers banded together and utilized their networks and autonomous culture to contest and exploit the limitations in French labor management for their own personal gains.
This Introduction provides an overview of the main arguments and contributions of the book to the literature on the environmental and economic history of French colonial Vietnam and the larger French colonial empire. It emphasizes how the book pays special attention to the significance of local networks and the role of diverse indigenous actors as it explores the formation of a regional and transnational coal regime of French colonial Vietnam. The Introduction also offers outlines of all chapters as well as the book’s key sources.
This chapter documents the conflicts among Đông Triều Coal Company (also known as SCDT), the city of Hải Phòng, and the French colonial government in Tonkin over the protection of potable water at a time when uncontrolled mining expansion in the Đông Triều highland, where SCDT was based, threatened to pollute the Hương River – Hải Phòng city’s source of potable water. This chapter argues that the French colonial state’s environment-centered attempts to safeguard the Hương River and public health, such as the creation of a massive water protection zone, were primarily driven by French concerns about the lack of hygiene and infectious diseases circulating within the indigenous communities located close to the Hương River rather than the industrial pollution caused by SCDT. The chapter also underlines issues pertaining to environmental laws, such as the logistical challenges of surveying and protecting water sources, and the lack of compliance with environmental regulations by big coal companies such as SCDT. More importantly, the chapter underscores the complex impact of mining expansion and environmental regulations on local ethnicities, such as the Dao communities.
This chapter documents the development of urban mining centers along the coal frontier of Quảng Yên and their impact on the landscape and its people. It examines the French vision of turning coal towns into orderly landscapes where spatial and racial segregation, as well as medical and hygiene surveillance, could be applied. The architects of these emerging mining towns expected their newly designed urban spaces to stabilize the restless and highly mobile indigenous migrant mining workforce while also protecting the towns’ tiny European population from epidemic diseases and security threats. However, several factors reduced these urban visions to a patchwork of modernity. Racial divides, security and medical concerns, coupled with strained resources, led to the unequal distribution of living space and public resources between the European and indigenous quarters. Infectious diseases, such as malaria, tuberculosis, cholera, and plague, spread rapidly across the overcrowded dormitories of mine workers. In addition, crime and illicit activities flourished on the commercial streets of these towns and cities.