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Inertial particles in wall-bounded turbulence are known to form streaks, but experimental evidence and predictive understanding of this phenomenon is lacking, especially in regimes relevant to atmospheric flows. We carry out wind tunnel measurements to investigate this process, characterizing the transport of microscopic particles suspended in turbulent boundary layers. The friction Reynolds number $Re_\tau = {O}(10^4)$ allows for significant scale separation and the emergence of large-scale motions, while the range of viscous Stokes number $St^+=18$–870 is relevant to the transport of dust and fine sand in the atmospheric surface layer. We perform simultaneous imaging of both carrier and dispersed phases along wall-parallel planes in the logarithmic layer, demonstrating that streamwise particle streaks largely overlap with large-scale low-speed flow regions. The fluid–particle slip velocity indicates that with increasing inertia, the particle streaks outlive the low-speed fluid streaks. Moreover, two-point statistics show that the width of the particle streaks increases linearly with Stokes number, bounded by the size of the coherent flow structures. Finally, the particle-sampled flow topology suggests that particle streaks reside between the legs of hairpin packets. From these observations, we infer a conceptual view of the formation of particle streaks in the frame of the attached eddy model. A scaling for the particle streaks’ width is derived as a function of $Re_\tau$ and $St^+$, which reproduces the measured trends and predicts widths ${O}(0.1)$ m in the atmospheric surface layer, comparable to aeolian streamers observed in the field.
We present a method for accurately determining the stability characteristics of spatially modulated shear layers. The algorithm can handle arbitrary commensurate states, which are not accessible to classical direct-numerical-simulation-based approaches. It uses spectral discretization of the field equations to handle field modulations and the spectrally accurate immersed boundary conditions method to handle the geometry modulations. The algorithm can deal with pattern interaction effects driven by modulations of different physical origins. Various tests demonstrate that the algorithm delivers spectral accuracy for eigenvalues and eigenfunctions. The algorithm can be easily extended to analyse many sources and patterns of modulation with minimal commitment to the user's time.
Our objective was to evaluate the psychometric properties of the culturally adapted NIH Toolbox African Languages® when used in Swahili and Dholuo-speaking children in western Kenya.
Method:
Swahili-speaking participants were recruited from Eldoret and Dholuo-speaking participants from Ajigo; all were <14 years of age and enrolled in primary school. Participants completed a demographics questionnaire and five fluid cognition tests of the NIH Toolbox® African Languages program, including Flanker, Dimensional Change Card Sort (DCCS), Picture Sequence Memory, Pattern Comparison, and List Sorting tests. Statistical analyses examined aspects of reliability, including internal consistency (in both languages) and test–retest reliability (in Dholuo only).
Results:
Participants included 479 children (n = 239, Swahili-speaking; n = 240, Dholuo-speaking). Generally, the tests had acceptable psychometric properties for research use within Swahili- and Dholuo-speaking populations (mean age = 10.5; SD = 2.3). Issues related to shape identification and accuracy over speed limited the utility of DCCS for many participants, with approximately 25% of children unable to match based on shape. These cultural differences affected outcomes of reliability testing among the Dholuo-speaking cohort, where accuracy improved across all five tests, including speed.
Conclusions:
There is preliminary evidence that the NIH Toolbox ® African Languages potentially offers a valid assessment of development and performance using tests of fluid cognition in Swahili and Dholuo among research settings. With piloting underway across other diverse settings, future research should gather additional evidence on the clinical utility and acceptability of these tests, specifically through the establishment of norming data among Kenyan regions and evaluating these psychometric properties.
The purpose of this paper is to analyse the effects of natural resources on income inequality conditional on economic complexity in 111 developed and developing countries from 1995 to 2016. The system-GMM results show that economic complexity reverses the positive effects of natural resource dependence on income inequality. Furthermore, results are robust to the distinction between dependence on point resources (fossil fuels, ores, and metals), dependence on diffuse resources (agricultural raw material), and resource abundance. Finally, there are significant differences between countries, depending on the level of ethnic fragmentation and democracy.
The finding that victims’ psychological problems tend to be exacerbated in lower-victimization classrooms has been referred to as the “healthy context paradox.” The current study has put the healthy context paradox to a strict test by examining whether classroom-level victimization moderates bidirectional within- and between-person associations between victimization and psychological adjustment. Across one school year, 3,470 Finnish 4th to 9th graders (Mage = 13.16, 46.1% boys) reported their victimization, depressive symptoms, anxiety, and self-esteem. Three types of multilevel models (cross-lagged panel, latent change score, and random-intercept cross-lagged panel) were estimated for each indicator of psychological adjustment. Findings indicated that the healthy context paradox emerges because classroom-level victimization moderates the prospective effect of victimization on psychological problems, rather than the effect of psychological problems on victimization. In classrooms with lower victimization, victims not only experience worse psychological maladjustment over time compared to others (between-person changes), but also higher maladjustment than before (absolute within-person changes).
Word list-learning tasks are commonly used to evaluate auditory-verbal learning and memory. However, different frequencies of word usage, subtle meaning nuances, unique word phonology, and different preexisting associations among words make translation across languages difficult. We administered lists of consonant-vowel-consonant (CVC) nonword trigrams to independent American and Italian young adult samples. We evaluated whether an auditory list-learning task using CVC nonword trigrams instead of words could be applied cross-culturally to evaluate similar learning and associative memory processes.
Participants and Methods:
Seventy-five native English-speaking (USA) and 104 native Italian-speaking (Italy) university students were administered 15-item lists of CVC trigrams using the Rey Auditory Verbal Learning Test paradigm with five study-test trials, an interference trial, and short- and long-term delayed recall. Bayesian t tests and mixed-design ANOVAs contrasted the primary learning indexes across the two samples and biological sex.
Results:
Performance was comparable between nationalities on all primary memory indices except the interference trial (List B), where the Italian group recalled approximately one item more than the American sample. For both nationalities, recall increased across the five learning trials and declined significantly on the postinterference trial, demonstrating susceptibility to retroactive interference. No effects of sex, age, vocabulary, or depressive symptoms were observed.
Conclusions:
Using lists of unfamiliar nonword CVC trigrams, Italian and American younger adults showed a similar performance pattern across immediate and delayed recall trials. Whereas word list-learning performance is typically affected by cultural, demographic, mood, and cognitive factors, this trigram list-learning task does not show such effects, demonstrating its utility for cross-cultural memory assessment.
Health benefits represent employers’ fastest growing operating expense. Efforts from human resources to control healthcare spending through restrictive plan design changes and corporate wellness programs may not achieve employer health and financial goals and may negatively impact employee outcomes. Employers are increasingly contracting directly with providers in order to access quality medical care and to control spending. The purpose of this practice-focused paper is to provide survey data collected from 10 employers as part of the quality improvement activities of a direct primary care (DPC) program. Overall, survey responses of employees engaged with DPC had higher patient satisfaction, group health plan rating, perceived organizational support, and job satisfaction than survey responses of those registered into the program but not yet engaged with a DPC physician. Implementation considerations and DPC characteristics are provided.
Richtmyer–Meshkov instability (RMI) at a light–heavy single-mode interface over a wide range of post-shock Atwood numbers $A_1$ is studied systematically through elaborate experiments. The interface generation and $A_1$ variation are achieved by the soap-film technology and gas-layer scheme, respectively. Qualitatively, the nonlinear interface evolution features, including spike, bubble and roll-up structures, are more significant in RMI with higher $A_1$. Quantitatively, both the impulsive model and an analytical linear model perform well in predicting the linear growth rate under a wide range of $A_1$ conditions. For the weakly nonlinear stage, the significant spike acceleration occurring when $A_1$ is high, which is observed experimentally for the first time, results in the evolution law of RMI with high $A_1$ being different from the counterpart with low or intermediate $A_1$. None of the considered nonlinear models is found to be applicable for RMI under all $A_1$ conditions, and the predictive capabilities of these models are analysed and summarized. Based on the present experimental results, an empirical nonlinear model is proposed for RMI over a wide range of $A_1$. Further, modal analysis shows that in RMI with high (low or intermediate) $A_1$, high-order harmonics evolve rapidly (slowly) and cannot (can) be ignored. Accordingly, for RMI with high (low or intermediate) $A_1$, the modal model proposed by Zhang & Sohn (Phys. Fluids, vol. 9, 1997, pp. 1106–1124) is less (more) accurate than the one proposed by Vandenboomgaerde et al. (Phys. Fluids, vol. 14, 2002, pp. 1111–1122), since the former ignores perturbation solutions higher than fourth order (the latter retains only terms with the highest power in time).
Neuropsychiatric symptoms (NPSs) after moderate-to-severe traumatic brain injury (TBI) have been well documented in WEIRD (Western, educated, industrialized, rich, and democratic) populations. In non-WEIRD populations, such as Vietnam, however, patients with TBI clinically remain uninvestigated with potential neuropsychiatric disorders, limiting on-time critical interventions. This study aims to (1) adapt the Vietnamese Neuropsychiatric Inventory (V-NPI), (2) examine NPSs after moderate-to-severe TBI and (3) evaluate their impact on caregiver burden and well-being in Vietnam.
Method:
Caregivers of seventy-five patients with TBI completed the V-NPI, and other behavior, mood, and caregiver burden scales.
Results:
Our findings demonstrated good internal consistency, convergent validity, and structural validity of the V-NPI. Caregivers reported that 78.7% of patients with TBI had at least three symptoms and 16.0% had more than seven. Behavioral and mood symptoms were more prevalent (ranging from 44.00% to 82.67% and from 46.67% to 66.67%, respectively) and severe in the TBI group. Importantly, NPSs in patients with TBI uniquely predicted 55.95% and 33.98% of caregiver burden and psychological well-being, respectively.
Conclusion:
This study reveals the first evidence for the presence and severity of NPSs after TBI in Vietnam, highlighting an urgent need for greater awareness and clinical assessment of these symptoms in clinical practice. The adapted V-NPI can serve as a useful tool to facilitate such assessments and interventions. In addition, given the significant impact of NPS on caregiver burden and well-being, psychosocial support for caregivers should be established.
This paper investigates the Confucian conception of political responsibility as a political virtue essential for an ordinary non-Confucian ruler's actualization of humane government by paying close attention to the early Confucian discourses of Heaven and disaster. After briefly discussing Confucius's seminal idea of responsibility, this paper shows how Mencius developed the political conception of responsibility, as a noncausal responsibility shared by the ruler and the virtuous ministers for a humane government, especially under the condition of natural disasters. It then discusses how the Han Confucian philosopher Dong Zhongshu reformulated the Mencian theory of responsibility and humane government under radically altered political circumstances by advancing a new version of Confucianism, central to which is the causal conception of political responsibility. This paper concludes by discussing how the evolution of Confucian political theory from Mencius to Dong Zhongshu should be understood with a view to the question of political legitimacy.
John Stuart Mill's account of his education in Autobiography (1873) is typically sifted through three interrelated sets of polarities: nurture/nature; reason/emotion; authority/autonomy. First, the father tried to mold the son's development towards a specific ideal, curbing his spontaneous growth. Second, James relentlessly sharpened John Stuart's analytical prowess to the almost total neglect of his emotional needs. Third, the authoritarianism involved in the design and execution of James Mill's curriculum rendered John Stuart Mill incapable of autonomy. This article argues that the dualities of nurture/nature and reason/emotion are not unambiguous, though ever-present in the reception of the younger Mill's education. Widening our perspective in their examination opens the possibility of a different assessment of that famous education being no education for autonomy.
Cook and Reckhow [5] pointed out that $\mathcal {N}\mathcal {P} \neq co\mathcal {N}\mathcal {P}$ iff there is no propositional proof system that admits polynomial size proofs of all tautologies. The theory of proof complexity generators aims at constructing sets of tautologies hard for strong and possibly for all proof systems. We focus on a conjecture from [16] in foundations of the theory that there is a proof complexity generator hard for all proof systems. This can be equivalently formulated (for p-time generators) without a reference to proof complexity notions as follows:
• There exists a p-time function g stretching each input by one bit such that its range $rng(g)$ intersects all infinite $\mathcal {N}\mathcal {P}$ sets.
We consider several facets of this conjecture, including its links to bounded arithmetic (witnessing and independence results), to time-bounded Kolmogorov complexity, to feasible disjunction property of propositional proof systems and to complexity of proof search. We argue that a specific gadget generator from [18] is a good candidate for g. We define a new hardness property of generators, the $\bigvee $-hardness, and show that one specific gadget generator is the $\bigvee $-hardest (w.r.t. any sufficiently strong proof system). We define the class of feasibly infinite $\mathcal {N}\mathcal {P}$ sets and show, assuming a hypothesis from circuit complexity, that the conjecture holds for all feasibly infinite $\mathcal {N}\mathcal {P}$ sets.
We present the general analytical solution of the Riemann problem (decay of a jump discontinuity) for non-convex relativistic hydrodynamics. In convex dynamics, an elementary nonlinear wave, i.e. a rarefaction or a shock, originates at the discontinuity and travels towards one of the initial states. Between the left and right waves, an equilibrium state appears represented by a contact discontinuity. The exact solution to the Riemann problem in convex relativistic hydrodynamics was first addressed by Martí & Müller (J. Fluid Mech., vol. 258, 1994, pp. 317–333). In non-convex dynamics, two sequences of elementary nonlinear waves move towards the left and right initial states. Solving the Riemann problem involves determining the types of wave developing and the equilibrium state where they coincide. The procedure consists of constructing the wave curves associated with the nonlinear waves in the pressure–velocity phase space, where the intersection of the wave curves indicates the equilibrium state. We describe the relation between the wave curves, the explicit formulas for their calculation, and the outline of the process for a correct derivation and representation of the waves in the spatial domain. We present examples of the exact solution of a Riemann problem that illustrate the complex phenomena of non-convex dynamics by using the phenomenological non-convex equation of state proposed by Ibáñez et al. (Mon. Not. R. Astron. Soc., vol. 476, 2017, pp. 1100–1110).
Subjective cognitive decline (SCD) and how much cognitive decline impacts one’s ability to perform instrumental activities of daily living (iADLs) are necessary elements of neuropsychological assessment when diagnosing mild cognitive impairment (MCI) and dementia. Though limited, the literature suggests that culture and self-appraisal of cognitive abilities are related. However, it is unclear if differences exist in the subjective elements of neuropsychological assessments between patients born in Anglosphere countries (Canada, the USA, and the UK) versus immigrants born elsewhere (International Group).
Method:
We conducted a retrospective chart review of advanced Parkinson’s disease (PD) patients (n = 764). Reports of SCD and iADL difficulties were extracted from neuropsychological reports and coded by two independent raters. We also examined responses on self- and family-rated questionnaires of executive functioning and iADL difficulties.
Results:
Anglosphere and International patients did not differ on overall, memory, or attention SCD, or overall iADL difficulties based on interviews. Anglosphere patients reported more executive and language SCD during the interview but International care-partners reported more current executive dysfunction on a questionnaire. International patients and care-partners reported more iADL difficulties on a questionnaire, which they ascribed to motor (not cognitive) symptoms. The effects on questionnaires were small and persisted after accounting for depression severity ratings.
Conclusion:
There were no consistent group differences in the number or pervasiveness of SCD or iADL difficulties reported by Anglosphere versus International groups. Immigration status has limited effect on these subjective elements and they should be given significant weight when diagnosing cognitive dysfunction in PD.