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We investigate the dynamics of a columnar Taylor–Green vortex array under strong stratification, focusing on Froude numbers $0.125\leq Fr \leq 1.0$, with the aim of identifying and understanding the primary instabilities that lead to the vortices’ breakdown. Linear stability analysis reveals that the fastest-growing vertical wavenumber scales with $Fr^{-1}$, while the dimensionless growth rate remains approximately constant. The most unstable eigenmode, identified as the mixed hyperbolic mode by Hattori et al. (J. Fluid Mech., vol. 909, 2021, A4), bears significant similarities to the zigzag instability, first discovered by Billant & Chomaz (J. Fluid Mech., vol. 418, 2000, pp. 167–188). Direct numerical simulations further confirm that the zigzag instability is crucial in amplifying initial random perturbations to finite amplitude, with the flow structure and modal growth rate consistent with the linear stability analysis. In particular, the characteristic vertical length scale of turbulence matches that of the fastest-growing linear mode. These findings underscore the broader relevance of the zigzag instability mechanism beyond its initial discovery in vortex pairs, demonstrating its role in facilitating direct energy transfer from vertically uniform vortical motions to a characteristic vertical length scale proportional to $Fr$ in strongly stratified flows.
The ideological and issue positions of parties are known to shape citizens’ political attitudes and voting behaviour. One important way to obtain estimates of parties’ positions is to ask experts to place parties on salient ideological dimensions. The Chapel Hill Expert Survey (CHES) has been collecting such estimates for democracies in Europe and elsewhere. CHES Canada adds to this project by providing estimates of party positions and characteristics of Canadian federal parties and provincial parties in Ontario and Quebec. This note introduces this new data source, clarifies how the data were collected and illustrates how the data can be used to (comparatively) study party politics in Canada.
As the population of Aotearoa New Zealand ages, informal family carers will play an increasingly important role in caring for older adults at home. Multi-generational living arrangements are a growing trend, particularly among Māori communities, where caring for older relatives within the family home is widespread. This article uses in-depth, semi-structured interviews with Māori whānau (extended family members) caring for kaumātua (older family members) at home to explore how carers experienced care coordination in the broader care collective. The findings centred on three interconnected factors that described the collective organisation of care: (1) whānau care as normal; (2) whānau care as collective coordination; and (3) whānau carer knowledge and needs as unseen. The findings show that although whānau care of kaumātua is highly valued, ‘structural holes’ within care systems contribute to challenges in care coordination. Despite extensive whānau support for kaumātua, primary carers often felt that their knowledge, preferences and self-care needs remained unseen and not translatable to those outside the everyday care situation. Rather than assuming an artificial binary difference between ‘collective’ and ‘individually oriented’ care contexts and cultures, analysing the cultural norms surrounding whānau care-giving confirms that collective care system members face similar and different challenges to carers with smaller caring capacities.
Gilles Deleuze est, parmi les penseurs français contemporains, celui ayant démontré la plus grande sensibilité à l’égard de la culture québécoise en intégrant quelques-unes de ses forces révolutionnaires dans son œuvre. C'est ce qu'illustre la première partie de l'article en faisant référence à des figures culturelles marquantes discutées par Deleuze : Jack Kérouac, Pierre Perrault, Michèle Lalonde, Norman McLaren et Alexis le Trotteur. L'article explore ensuite la réception de Deleuze au Québec dans et à l'extérieur des milieux universitaires en montrant que la pensée deleuzienne a pris part à la contre-culture avant d'acquérir une visibilité au sein des départements de philosophie.
Seven decades after Brown v. Board, Black students continue to lag White students. This article analyzes six experiments conducted over three decades to study whether, consistent with social identity theory, White Americans are more supportive of funding increases for nonracially targeted educational programs that benefit their racial ingroup compared to race-targeted programs. We also ask whether racial prejudice is a factor, if implicit or explicit racial priming accounts for any observed differences, and if the effects have changed over time. Our results show that consistent with social identity theory, White Americans are more likely to favor funding increases for public schools or programs for poor children, categories that are majority White, than programs targeted to Black children. Furthermore, we find no evidence of implicit or explicit racial priming. Across all experiments and all years, interactions between racial priors and the treatments are null. We conclude that ingroup favoritism, not prejudice nor racial priming, explains racially discriminatory support for increases in education funding.
Let $r$ be any positive integer. We prove that for every sufficiently large $k$ there exists a $k$-chromatic vertex-critical graph $G$ such that $\chi (G-R)=k$ for every set $R \subseteq E(G)$ with $|R|\le r$. This partially solves a problem posed by Erdős in 1985, who asked whether the above statement holds for $k \ge 4$.
In this paper, we study a connection between disintegration of measures and geometric properties of probability spaces. We prove a disintegration theorem, addressing disintegration from the perspective of an optimal transport problem. We look at the disintegration of transport plans, which are used to define and study disintegration maps. Using these objects, we study the regularity and absolute continuity of disintegration of measures. In particular, we exhibit conditions for which the disintegration map is weakly continuous and one can obtain a path of measures given by this map. We show a rigidity condition for the disintegration of measures to be given into absolutely continuous measures.
Systemic changes in multiple diseases may influence the onset of dementia. However, the specific temporality between exposure diseases and dementia remains uncertain.
Aims
By characterising the full spectrum of temporal disease trajectories before dementia, this study aims to yield a global picture of precursor diseases to dementia and to provide detailed instructions for risk management and primary prevention of dementia.
Method
Using the multicentre, community-based prospective UK Biobank, we constructed disease trajectories before dementia utilising the phenome-wide association analysis, paired directional test and association quantification. Stratified disease trajectories were constructed by dementia subtypes, gender, age of diagnosis and Apolipoprotein E (ApoE) status, respectively.
Results
Our study population comprised 434 266 participants without baseline dementia and 4638 individuals with all-cause dementia. In total, 1253 diseases were extracted as potential components of the disease trajectory before dementia. We identified three clusters of disease trajectories preceding all-cause dementia, initiated by circulatory, metabolic and respiratory diseases occurring approximately 5–15 years before dementia. Cerebral infarction or chronic renal failure following chronic ischaemic heart disease was the specific trajectory before vascular dementia. Apolipoprotein E (ApoE) ε4 non-carriers exhibited more complex trajectories compared with carriers. Lipid metabolism disorders remained in the trajectories regardless of dementia subtypes, gender, age of diagnosis and ApoE status.
Conclusions
This study provides a comprehensive view of the longitudinal disease trajectories before dementia and highlights the potential targets of midlife cardiometabolic dysfunction for dementia screening and prevention.
Several models of maternal undernutrition reveal impairment of testicular development and compromise spermatogenesis in male offspring. The expansion of the litter size model, valuable for studying the impact of undernutrition on early development, has not yet been used to evaluate the consequences of early undernutrition in the adult male reproductive system. For this purpose, pups were raised in either normal litter (ten pups/dam) or large litter (LL; sixteen pups/dam). On postnatal day 90, sexual behaviour was evaluated or blood, adipose and reproductive tissues were collected for biochemical, histological and morphological analysis. Adult LL animals were lighter and thinner than controls. They showed increased food intake, but decrease of retroperitoneal white adipose tissue weight, glycaemia after oral glucose overload and plasma concentration of cholesterol. Reproductive organ weights were not altered by undernutrition, but histopathological analysis revealed an increased number of abnormal seminiferous tubules and number of immature spermatids in the tubular lumen of LL animals. These animals also showed reduction in total spermatic reserve and daily sperm production in the testes. Undernutrition decreased the number of Sertoli cells, and testosterone production was increased in the LL group. Mitochondrial activity of spermatozoa remained unchanged between experimental groups, suggesting no significant impact on the energy-related processes associated with sperm function. All animals from both experimental groups were considered sexually competent, with no significant difference in the parameters of sexual behaviour. We conclude that neonatal undernutrition induces histological and physiological testicular changes, without altering sperm quality and sexual behaviour of animals.
For too long, questions of racism and colonialism have not been part of historical sociology’s understanding of modernity. Yet, a new generation of scholars has begun to address this, placing racism and empire at the center of their inquiries. This new generation looks to previously marginalized scholars for guidelines and inspiration. In line with this shift in historical sociology, this paper brings the work of W.E.B. Du Bois and other writers in the Black Radical Tradition to bear on longer-standing analytic and methodological debates: How do these authors allow us to think about theory-building and comparison? What is the goal of explanation? How should we approach archives and sources? Building on these insights, this paper explains how the work of Du Bois and the Black Radical Tradition provides a model for a new historical sociology, and a framework that allows us to see the connections between racism, colonialism, and modernity.
The first insights on habitat and phylogenetic origin of a newly found population of Solen marginatus are provided in the mid-North Atlantic Azores archipelago, in the bay of Praia da Vitória, Terceira Island. Distribution is confined to the northern portion and most sheltered part of the bay down to 14.2 m depth. Densities with an average of 12.69 individuals/m2 were found at 8.4 m depth, using 4 × 20 sqm visual transects. Sizes of shell length between 10 and 12 cm comprised 60% of collected specimens (n = 118), ranging between 8.79 and 15.4 cm and averaging 11.28 cm. Considering shell length, the high densities and dispersion area, a settlement period above 20 years is estimated. Greater genetic affinity was found in the Ria de Aveiro (North of Portugal) and the Asturias populations (North of Spain). The source origin remains undetermined, with intentional or non-intentional anthropogenic introduction, as well as natural dispersion remaining possible, although more unlikely. Due to the commercial value of this species, a new clam fishery is likely to develop in the area, requiring further studies and immediate conservation measures.
Casuarina equisetifolia L. commonly called whistling pine is an economically and industrially important tree species with global significance. Although species possess versatile importance worldwide, efforts imparted for selection and designing a robust model of selection index are inadequate. The selection process, based on quantitative and qualitative traits, identified 15 superior trees from the eastern coastal plain of Odisha. These superior trees showcased exceptional qualitative and quantitative attributes. Correlation analysis highlighted key similarities among various traits like volume and above ground biomass (AGB), volume and diameter at breast height (DBH), DBH and AGB, DBH and Tree Height (TH), crown length (CL), height, AGB and height. Principal component analysis emphasized substantial contributions of traits like DBH, height, CL, crown width, AGB and volume across different clusters. Furthermore, culmination resulted in a comprehensive selection index, integrating both qualitative and quantitative characters, reaching 52.04, signifying superior performance among specific accessions. The current study provides valuable insights into selection and designing optimal selection index of C. equisetifolia, guiding future decisions concerning optimal wood production and resource management.
We propose a simple method to identify unstable parameter regions in general inviscid unidirectional shear flow stability problems. The theory is applicable to a wide range of basic flows, including those that are non-monotonic. We illustrate the method using a model of Jupiter's alternating jet streams based on the quasi-geostrophic equation. The main result is that the flow is unstable if there is an interval in the flow domain for which the reciprocal Rossby Mach number (a quantity defined in terms of the zonal flow and potential vorticity distribution), surpasses a certain threshold or ‘hurdle’. The hurdle height approaches unity when we can take the hurdle width to greatly exceed the atmosphere's intrinsic deformation length, as holds on gas giants. In this case, the Kelvin–Arnol’d sufficient condition of stability accurately detects instability. These results improve the theoretical framework for explaining the stable maintenance of Jupiter and Saturn's jets over decadal time scales.
Automated dispensers that dilute concentrated disinfectants with water are commonly used in healthcare facilities. In a point-prevalence product evaluation, 9 of 10 (90%) hospitals using dilutable disinfectants had 1 or more malfunctioning dispensers. Twenty-nine of 107 (27.1%) systems dispensed product with lower-than-expected concentrations, including 15 (14.0%) with no detectable disinfectant.
This article explores the militarisation of the North Korean police and the establishment of specialised units, including the Railroad and Maritime Police, and the Korean-Manchurian border guard. The analysis primarily draws from unpublished Soviet archival material. Contrary to the assumption that strengthening the North Korean police under Soviet military administration was aimed at providing a backbone to the North Korean regime, our examination reveals that, at least initially, it was driven by the urgent need to address immediate challenges in public security. The initial crisis arose with anti-trusteeship protests and worsened when the Soviets initiated land reform, coinciding with a series of terrorist attacks against North Korean politicians and Soviet military units. The article also sheds light on the background processes that led to the creation of specialised police units such as the Railroad Police and the Maritime Police. Contrary to common perceptions, these units were not designed to become military units from the outset. Soviet documents clearly reveal that their primary function was to assist the Soviets in guarding the North Korean railroad and coastline. The Soviets initiated and controlled the establishment of the Korean-Manchurian border guard to address issues on the northern border of Korea.
Days of antibiotic spectrum coverage (days of ASC: DASC) is a metric for antibiotic usage calculated by ASC scores for spectrum and addresses limitations of days of therapy (DOT), which does not include spectrum. This study aims to investigate whether ASC-related metrics offer different aspects compared to aggregated DOT for all antibiotics (DOTtotal) and to assess their correlation in evaluating the impact of antimicrobial stewardship team (AST) programs.
Design:
Retrospective.
Setting:
A single center within an 845-bed hospital.
Methods:
Trends in DOTtotal, DASC, and the DASC/DOT ratio, representing the average spectrum coverage per therapy day, were analyzed pre- and post-AST programs (April 2018) from January 2015 to December 2023, using interrupted time series analysis. Independent of the DASC/DOT, we also advocated ASC-stratified DOT (ASDOT), which facilitates comprehensive evaluation of DOT across ASC scores of <6, 6–10, and >10, representing narrow-, intermediate-, and broad-spectrum antibiotics.
Results:
Among inpatients, AST programs significantly moderated the increasing trends of these metrics. Specifically, although the rates of increase in DOTtotal and DASC were slowed or plateaued, the DASC/DOT ratio decreased (P < 0.001). ASDOT metrics revealed a decrease and subsequent plateau in DOTtotal for the broad- and intermediate-spectrum antibiotics, with an increase observed for the narrow-spectrum antibiotics (P < 0.001 for each). DASC did not provide additional insights in the outpatient’s population.
Conclusions:
The study demonstrates that ASC-related metrics may yield different and useful conclusions about the effectiveness of AST programs for inpatients.
We conducted a retrospective cohort study to identify factors influencing intravenous (IV) versus oral antibiotic therapy in first-episode prosthetic joint infections. Of the 34/78 (44%) cases treated intravenously, negative cultures (26%), concomitant infections necessitating IV antibiotics (21%), and delays in susceptibility testing (15%) were the most common reasons for IV therapy.