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During stroke reversals, insect wings interact with their own wake flow from the preceding half-stroke, resulting in an unsteady aerodynamic mechanism known as ‘wing–wake interaction’ or ‘wake capture’. To better elucidate this mechanism, we numerically solved the incompressible Navier–Stokes equations at Reynolds numbers $10^2$ and $10^3$. Simulations were conducted for wing planforms defined using the beta function distribution with varying aspect ratios ($AR=2\unicode{x2013}6$) and radial centroid locations ($\hat {r}_1=0.4\unicode{x2013}0.6$), whilst employing representative normal hovering kinematics. The wake development from the considered flapping wing planforms was investigated, and the wake capture contribution to aerodynamic force production was quantified by comparing the force generation between the fifth and first stroke cycles at multiple sections along the wingspan. Our results revealed that on the inboard wing region experiencing an attached leading-edge vortex (LEV) structure, wing–wake interaction is dominated by an unsteady downwash effect, resulting in a reduction in local force production. However, in regions closer to the wingtip experiencing detachment of the LEV, wing–wake interaction is dominated by an unsteady upwash effect, leading to an increase in local force production. Consequently, the global wake capture force production is controlled by the extent of LEV detachment, which primarily increases with the increase of wing aspect ratio. This suggests that for normal hovering flapping wings, the typical loss in translational force production due to wingtip stall is partially mitigated by wake capture effects.
Social cognition is commonly altered in people with psychosis. Two main brain networks have been implicated: the default-mode network (DMN), which is associated with socio-cognitive processing, and the salience network (SN) associated with socio-affective processing. Disturbances to the resting-state functional connectivity of these networks have been identified in schizophrenia and high-risk individuals, but there have been no studies in adolescents displaying distinct trajectories of subclinical psychotic-like experiences (PLEs). To address this, the present study measured SN and DMN resting-state connectivity in a unique longitudinally followed sample of youth (n = 92) presenting with typical and atypical 4-year PLE trajectories. Compared to the typically developing low PLE control group, the atypical increasing PLE trajectory displayed reduced connectivity between the SN and DMN, increased connectivity between left and right insula, and widespread dysconnectivity from the insula and amygdala. These alterations are similar to those reported in schizophrenia and clinical high-risk samples, suggesting that early detection may be useful for mapping the developmental trajectories of psychotic disorders.
The authors’ primary goal in this paper is to enhance the study of $T_0$ topological spaces by using the order of specialization of a $T_0$-space to introduce the lower topology (with a subbasis of closed sets $\mathord{\uparrow } x$) and studying the interaction of the original topology and the lower topology. Using the lower topology, one can define and study new properties of the original space that provide deeper insight into its structure. One focus of study is the property R, which asserts that if the intersection of a family of finitely generated sets $\mathord{\uparrow } F$, $F$ finite, is contained in an open set $U$, then the same is true for finitely many of the family. We first show that property R is equivalent to several other interesting properties, for example, the property that all closed subsets of the original space are compact in the lower topology. We then find conditions under which these spaces are compact, well-filtered, and coherent, a weaker variant of stably compact spaces. We also investigate what have been called strong $d$-spaces, develop some of their basic properties, and make connections with the earlier considerations involving spaces satisfying property R. Two key results we obtain are that if a dcpo $P$ with the Scott topology is a strong $d$-space, then it is well-filtered, and if additionally the Scott topology of the product $P\times P$ is the product of the Scott topologies of the factors, then the Scott space of $P$ is sober. We also exhibit connections of this work with de Groot duality.
We consider steady surface waves in an infinitely deep two-dimensional ideal fluid with potential flow, focusing on high-amplitude waves near the steepest wave with a 120$^{\circ }$ corner at the crest. The stability of these solutions with respect to coperiodic and subharmonic perturbations is studied, using new matrix-free numerical methods. We provide evidence for a plethora of conjectures on the nature of the instabilities as the steepest wave is approached, especially with regards to the self-similar recurrence of the stability spectrum near the origin of the spectral plane.
The concept of heightened human rights due diligence (hHRDD) is often used to address corporate responsibilities in situations of armed conflict. For companies in these contexts, the first step is to assess whether their activities impact the conflict and its dynamics, and, as a result, whether they are involved in conflict-related human rights abuses. However, companies often find that they have no impact on the conflict. Should companies in these scenarios just focus on regular human rights due diligence (HRDD)? This piece aims to illustrate, based on the example of Ukraine, the human rights challenges that emerge during a war which companies with no influence on the conflict still face and to respond to the question of whether in such situations companies should still engage in hHRDD or continue to conduct HRDD as usual.
We construct a new stochastic interest rate model with two stochastic factors, by introducing a stochastic long-run equilibrium level into the Vasicek interest rate model which follows another Ornstein–Uhlenbeck process. With the interest rate under the Black–Scholes model being assumed to follow the newly proposed model, a closed-form representation of European option prices is successfully presented, when the analytical characteristic function of the underlying log-price under a forward measure is derived. To assess the model performance, a preliminary empirical study is conducted using S&P 500 index and its options, with the Vasicek model and an alternative two-factor Vasicek model taken as benchmarks.
Cognitive reserve (CR) is typically operationalized as episodic memory residualized on brain health indices. The dimensionality of more generalized models of CR has rarely been examined.
Methods:
In a sample of N = 113 dementia-free older adults (ages 62–86 years at MRI scan; 58.4% women), the domain-specific representation of general cognition (COG) before vs. after residualization on brain indices (brain volume loss, cerebral blood flow, white matter hyperintensities) was compared (i.e., COG vs. CR). COG and CR were assessed by 15 tasks spanning five domains: processing speed, verbal memory, visuospatial memory, fluid reasoning, and vocabulary. Measurement invariance and item-construct representation were tested in a series of structural factor analyses. COG and CR were then examined in relation to 22 risk and protective factors and dementia status at time of death.
Results:
Item-factor loadings differed such that CR more strongly emphasized fluid reasoning. More years of education, higher occupational class, more hobbies/interests, and fewer difficulties with personal mobility similarly predicted better COG and CR. Only the sub-domain of visuospatial memory (both before and after residualization) was associated with conversion to dementia by end-of-life (r = −.30; p = .01).
Conclusions:
Results provide tentative support for the role of fluid reasoning (intelligence) as a potential compensatory factor for age- and/or neuropathology-related reductions in processing speed and memory. Intellectually stimulating work, efforts to preserve personal mobility, and a diversity of hobbies and interests may attenuate age- and/or pathology-related reductions in cognitive functioning prior to dementia onset.
Normal aging often leads to cognitive decline, and oldest old people, over 80 years old, have a 15% risk of developing neurodegenerative diseases. Therefore, it is important to have appropriate tools to assess cognitive function in old age. The study aimed to provide new norms for neuropsychological tests used to evaluate the cognitive abilities in people aged 80 years and older in France, focusing on the impact of education and gender differences.
Method:
107 healthy participants with an average age of 85.2 years, with no neurological history or major cognitive deficits were included. A comprehensive neuropsychological assessment was performed, covering several cognitive functions such as memory, visuospatial abilities, executive functions, attention, processing speed, and praxis.
Results:
Individuals with lower levels of education performed poorly on some tests and took longer to complete. Gender differences were observed, with women outperforming men in verbal episodic memory, while men showed better performance in visuoconstructive tasks. The participants showed lower performance in verbal episodic memory compared to norms established in previous French studies. In relation to executive functions, participants were slower to perform complex tasks than participants in previous studies.
Conclusion:
This study provides cognitive norms specifically adapted to the oldest old population, which differ from established norms for younger aging adults. It highlights the importance of including these norms in future clinical and scientific investigations. The findings underscore the importance of education on cognitive abilities and emphasize the need to consider gender differences when assessing cognitive functions in aging populations.
The background potential energy (BPE) is the only reservoir that double diffusive instabilities can tap their energy from when developing from an unforced motionless state with no available potential energy (APE). Recently, Middleton and Taylor linked the extraction of BPE into APE to the sign of the diapycnal component of the buoyancy flux, but their criterion can predict only diffusive convection instability, not salt finger instability. Here, we show that the problem can be corrected if the sign of the APE dissipation rate is used instead, making it emerge as the most fundamental criterion for double diffusive instabilities. A theory for the APE dissipation rate for a two-component fluid relative to its single-component counterpart is developed as a function of three parameters: the diffusivity ratio, the density ratio, and a spiciness parameter. The theory correctly predicts the occurrence of both salt finger and diffusive convection instabilities in the laminar unforced regime, while more generally predicting that the APE dissipation rate for a two-component fluid can be enhanced, suppressed, or even have the opposite sign compared to that for a single-component fluid, with important implications for the study of ocean mixing. Because negative APE dissipation can also occur in stably stratified single-component and doubly stable two-component stratified fluids, we speculate that only the thermodynamic theory of exergy can explain its physics; however, this necessitates accepting that APE dissipation is a conversion between APE and the internal energy component of BPE, in contrast to prevailing assumptions.
Let G be a connected semisimple real algebraic group. For a Zariski dense Anosov subgroup $\Gamma <G$ with respect to a parabolic subgroup $P_\theta $, we prove that any $\Gamma $-Patterson–Sullivan measure charges no mass on any proper subvariety of $G/P_\theta $. More generally, we prove that for a Zariski dense $\theta $-transverse subgroup $\Gamma <G$, any $(\Gamma , \psi )$-Patterson–Sullivan measure charges no mass on any proper subvariety of $G/P_\theta $, provided the $\psi $-Poincaré series of $\Gamma $ diverges at its abscissa of convergence. In particular, our result also applies to relatively Anosov subgroups.
Amputation as a life-saving measure for earthquake-trapped patients is supported by WHO and INSARAG guidelines. However, implementing these guidelines in highly stressful contexts can complicate decision-making. This report presents a case of life-saving amputation during the 2023 Turkey earthquake, adhering to recommended guidelines. The 16-year-old patient was trapped for 55 hours in a narrow corridor. Extensive interdisciplinary discussions led to the decision for a field amputation after alternative rescue attempts failed. Consent was obtained from the family, given the patient’s delirium. Meticulous planning and anesthesia using midazolam and ketamine ensured successful amputation with minimal blood loss. Challenges encountered during the disaster response were discussed. Delays in administering antibiotics, a lack of cervical protection, ethical dilemmas, psychological concerns, and legal implications were highlighted. Continued improvement and addressing ethical, legal, and psychological aspects are essential for optimal disaster response outcomes.
To capture the distortion of exploratory activity typical of patients with spatial neglect, traditional diagnostic methods and new virtual reality applications use confined workspaces that limit patients’ exploration behavior to a predefined area. Our aim was to overcome these limitations and enable the recording of patients’ biased activity in real, unconfined space.
Methods:
We developed the Free Exploration Test (FET) based on augmented reality technology. Using a live stream via the back camera on a tablet, patients search for a (non-existent) virtual target in their environment, while their exploration movements are recorded for 30 s. We tested 20 neglect patients and 20 healthy participants and compared the performance of the FET with traditional neglect tests.
Results:
In contrast to controls, neglect patients exhibited a significant rightward bias in exploratory movements. The FET had a high discriminative power (area under the curve = 0.89) and correlated positively with traditional tests of spatial neglect (Letter Cancellation, Bells Test, Copying Task, Line Bisection). An optimal cut-off point of the averaged bias of exploratory activity was at 9.0° on the right; it distinguished neglect patients from controls with 85% sensitivity.
Discussion:
FET offers time-efficient (execution time: ∼3 min), easy-to-apply, and gamified assessment of free exploratory activity. It supplements traditional neglect tests, providing unrestricted recording of exploration in the real, unconfined space surrounding the patient.
Rapid technological development means that the ground on which recent academic studies and public debates about the future of work organisation are based is shifting too rapidly for predictions to be credible. Organisational studies scholars have provided a counterpoint to this futuristic, speculative debate about the world of tomorrow with studies that contextualise seemingly new trends within a longer history of industrial capitalism. In this article, using Moritz Altenried's The Digital Factory (2022) as a starting point, I further explore the historical contextualisation of two aspects of platform capitalism: its de-spatialisation and its use of “autonomy”.
More than two-thirds of women during childbearing years (20–39 years old) are overweight or obese in the United States, with protein intake among 20–49-year-old women being 1.6 times higher than recommended (75.4 g/day versus 46 g/day) that can be considered as a relatively high-protein diet (HPD). Both gestational obesity and HPDs during gestation adversely affect offspring health. This study investigates the impact of HPDs fed during gestation and lactation on obese mothers and their offspring in Wistar rats. Dams randomized to either a normal-protein diet (NPD) or HPD (n = 12/group). Pups from each maternal group were weaned to either NPD or HPD for 17 weeks (n = 12/group). No effect of maternal or weaning diet on food intake, body weight, or body fat/weight ratio was observed. However, NPD dams exhibited higher glucose area under the curve compared with HPD dams (p < 0.03). At weaning, offspring born to NPD dams showed higher fasting plasma glucose (P < 0.03) and insulin/glucose ratio (P = 0.05) than those born to HPD dams. The Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) index was higher in offspring born to NPD dams (P < 0.04) and weaned to NPD (P < 0.05) at week 17. These findings underscore the role of high-protein maternal and weaning diets in pregnancy outcomes for obese mothers, particularly in glucose homeostasis, although gestational obesity may overshadow other parameters. Further research is needed to fully understand the impact on both maternal and offspring health and their underlying mechanisms in this context.
This study describes the presence of the royal cucumber Parastichopus regalis (Cuvier, 1817) in The Natural Park of Ria Formosa (NPRF), Portugal. A single individual was observed during a monitoring scuba dive at a depth of 3 m inside this shallow mesotidal lagoon. The most plausible explanation for this occurrence is attributed to the rejection by trawlers when returning to their home port from their fishing grounds. This marine species has a deeper distribution outside the lagoon and is commonly captured as by-catch and subsequently discarded. This study also alerts us to the growing presence of non-indigenous species and the emergent threat of new invasions, highlighting the need to adopt biosecurity measures, like good practices for fishers when dealing with discards to avoid new species introductions in this fragile coastal marine habitat.
To capture prey more efficiently, cetaceans can display a wide range of foraging tactics to separate individual prey. Barrier feeding tactics are performed to restrict prey movements, using natural and non-natural barriers and some species can even create barriers with their own bodies. Mud ring feeding has been observed in bottlenose dolphins in Florida Bay and in Chetumal-Corozal Bay, where ring-maker dolphins create ring-shaped mud plumes to encircle fish schools. Here, we document for the first time Guiana dolphins performing the mud ring feeding behaviour in the Cananéia estuarine system, in the southern portion of the state of São Paulo, Brazil. A total of 11 dolphins were recorded in four expeditions through aerial footage engaging in the behaviour. These findings expand our knowledge about the behavioural plasticity of the species and builds upon existing records of mud ring feeding behaviour in cetaceans.