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Studies on tillering dynamics are essential to understand the aspects underlying the persistence and adaptation pathways of grass communities, especially in more complex multispecific pastures. This study aimed to assess the tillering dynamics and population stability of Andropogon gayanus cv. Planaltina (PG), Megathyrsus maximus cv. Massai (MG) and Urochloa brizantha cv. BRS Piatã (PP) grown as monocultures and as a mixture. The treatments corresponded to three grasses described above. Sixteen 180 m2 plots were randomly assigned and managed intermittently under manual harvest at pre- and post-harvest heights of 35 and 17.5 cm, respectively, for two years. During autumn/winter/early spring, when resource availability is limited by abiotic factors, pasture population stability was ensured by the conservation strategy of all species, mainly through the high tiller survival rate (85.5 ± 0.32). In late spring and summer, the capture strategy was prioritized for all species, with stability ensured through high tiller appearance rates (30.3 ± 0.80 and 40.4 ± 1.47, respectively), which compensated for the high tiller death rate (28.7 ± 1.10) and resulted in greater species turnover during these both seasons. The association among PG, MG and PP in a mixture allows species to coexist with relatively stable populations and tillering dynamics, similar to their monocultures. These findings represent a step forward in our understanding of mixed swards stability and indicate that such associations could be viable alternatives to palisadegrass monocultures in tropical regions. Further research should test this mixed sward under grazing, during medium to long-term.
This study presents a modified intermediate long wave (mILW) equation derived from the Navier–Stokes equations via multi-scale analysis and perturbation expansion, aimed at describing internal solitary waves (ISWs) in finite-depth, stratified oceans. Compared to the classical ILW model, the proposed mILW equation incorporates cubic nonlinearities and captures the dynamical behaviour of large-amplitude ISWs more accurately. The equation reduces to the modified Korteweg–de Vries equation and modified Benjamin–Ono equations in the shallow- and deep-water limits, respectively, thus providing a unified framework across varying depth regimes. Soliton solutions are constructed analytically using Hirota’s bilinear method, and numerical simulations investigate wave–wave interactions, including rogue waves and Mach reflection. Furthermore, a smooth tanh-type density profile is adopted to reflect realistic stratification. Associated vertical modal structures and vertical velocity fields are analysed, and higher-order statistics (skewness and kurtosis) are introduced to reveal the density dependence of wave asymmetry. The results offer new insights into the nonlinear dynamics of ISWs, with implications for ocean mixing, energy transport and submarine acoustics.
John Cooper contends that ancient philosophers shared certain fundamental assumptions about the “motivating power” of truth and knowledge that have been abandoned by post-Renaissance philosophers. Consequently, he claims that those seeking philosophy as a guide to the good life can only find it in the works of ancient philosophers. I challenge that conclusion by arguing that philosophy as a way of life has not disappeared but has evolved. A key indicator of this continuity is the enduring presence of “professional” philosophers who, like their ancient counterparts, remain concerned with what used to be called “the state of one’s soul.”
This article argues that a pervasive but confused theory of free will is driving unwarranted resistance to behavioral genetic research and undermining the concept of personal responsibility enshrined in our moral and legal conventions. We call this the theory of ‘free-will-by-subtraction’. A particularly explicit version of this theory has been propounded by the psychologist Eric Turkheimer, who has proposed that human agency can be scientifically quantified as the behavioral variation that remains unexplained after known genetic and environmental causes have been accounted for. This theory motivates resistance to research that suggests genetic differences substantially account for differences in human behavior because that is seen to reduce the scope of human freedom. In academic philosophy, free-will-by-subtraction theory corresponds to a position called ‘libertarian incompatibilism’, which holds that human beings are not responsible for behavior that has antecedent causes yet maintains that free will nonetheless exists because some fraction of human behavioral variation is self-caused. However, this position is rejected by most professional philosophers. We argue that libertarian incompatibilism is inconsistent with a secular materialist outlook in which all human behavior is understood to have antecedent causes whether those causes are known to science or not — an outlook Turkheimer shares. We show that Turkheimer sustains this contradiction by adopting an untenable position we call ‘epistemic libertarianism’, which holds that antecedent causes of our behavior only infringe on our freedom if we know about them. By contrast, the overwhelming majority of secular materialist philosophers support a position called ‘compatibilism’, which maintains that free will is compatible with the comprehensive causation of human behavior. We show that compatibilism neutralizes the threat that genetic explanation poses to human agency and rescues a generous conception of personal responsibility that aligns with our moral intuitions.
Some scholars argue that democratic stability requires political elites to practice forbearance: roughly speaking, “restraint in deploying their institutional prerogatives” (Levitsky and Ziblatt, How Democracies Die, 2018). The article proposes a novel conception of forbearance as a mechanism of democratic stability. According to this view, public officials exercise forbearance when they refrain from actions of uncertain legitimacy, actions that, while in fact compatible with democracy’s constitutive rules, are not commonly known to be. The argument is that such actions, by provoking divergent reactions among citizens, create uncertainty about the extent to which others are willing to resist breaches of democracy’s rules. This uncertainty undermines their ability to coordinate responses to genuine abuses of power in the future. The article concludes with observations about the normative implications of the theory, introducing the concept of the “Democrat’s Dilemma” to illustrate the difficulties of knowing when democrats ought to practice forbearance.
Chemical weapons are among the weapons of mass destruction that have caused huge human casualties in the last century. Because of their easy manufacturing and accessibility, and despite international treaties, they remain a serious threat to global security, not just limited to military staff but also to civilian populations and the environment in the short and long term.
Unstable approaches contribute significantly to accidents during the critical approach and landing phases of flight, many of which could have been prevented by executing a go-around. This review investigates cognitive lockup, a tendency to adhere to task completion despite shifting priorities, and its role in aviation incidents. Specifically, we explore the psychological underpinnings of cognitive lockup, the influence on pilot decision-making and potential mitigation strategies. We examine factors such as task completion bias, framing effects and the perceived cost of task switching, and provide recommendations for training and policy modifications to reduce cognitive lockup. Aviation safety in critical flight phases can be improved through enhanced pilot training, mindfulness techniques, positive policy framing and AI-based alert systems.
An improved identification algorithm is adopted to calibrate the kinematic parameters of the serial-parallel robot, which improves the motion accuracy of the end-effector. Firstly, a kinematic model of the serial-parallel robot is constructed based on the closed-loop vector method. Secondly, a kinematic error model is established by combining geometric error analysis with the vector differential method. Then, with the effective separation of compensable and non-compensable error sources, an identification model of kinematic parameters is constructed. Finally, an improved pivot element weighted iterative algorithm is used to identify the geometric error parameters. Through actual pose measurement, MATLAB is used to simulate the calibration process. The simulation and experimental results show that after kinematic calibration, compared with the traditional least squares method, the improved identification algorithm can significantly reduce the end-effector pose error of the serial-parallel robot, thus effectively improving the motion accuracy of the end-effector.
where $\alpha,\beta$ are real parameters, $n \gt 2,\, q \gt k\geqslant 1$ and $S_k(D^2v)$ stands for the k-Hessian operator of v. Our results are based mainly on the analysis of an associated dynamical system and energy methods. We derive some properties of the solutions of the above equation for different ranges of the parameters α and β. In particular, we describe with precision its asymptotic behaviour at infinity. Further, according to the position of q with respect to the first critical exponent $\frac{(n+2)k}{n}$ and the Tso critical exponent $\frac{(n+2)k}{n-2k}$ we study the existence of three classes of solutions: crossing, slow decay or fast decay solutions. In particular, if k > 1 all the fast decay solutions have a compact support in $\mathbb{R}^n$. The results also apply to construct self-similar solutions of type I to a related nonlinear evolution equation. These are self-similar functions of the form $u(t,x)=t^{-\alpha}v(xt^{-\beta})$ with suitable α and β.
Nutrition plays a key role in shaping children’s eating behaviors, which can be influenced by environment and social interactions, making careful management essential at home and school. This cross-sectional study aimed to evaluate the perceptions of caregivers in these settings regarding the consumption and eating behaviors of children aged 3-6 years. Food preferences and frequency questionnaires were administered to teachers, children, and their caregivers, supplemented by free drawing and coloring activities. The results revealed discrepancies between parents and teachers, with parents recognizing the importance of fruits and vegetables for health and reporting that children have access to these foods at home. Although parents recognized the importance of vegetable consumption, teachers did not share this perception, as they observed limited access to these foods among children and even reported difficulties in introducing them into the school environment. The most consumed foods during main meals were rice, beans, vegetables, and meats, while fruits and dairy products were predominant in breakfast and snacks. Children frequently mentioned fruits like watermelon, strawberry, and apple in free drawing and coloring activities. These findings highlight significant differences in perceptions between parents and teachers regarding children’s access to healthy foods, underscoring the need for improved communication to promote healthier eating habits.
The timing for intervention in patients with significant chronic aortic regurgitation is based on adult guidelines and criteria which may not apply to children. There is limited data on the use of cardiac MRI parameters to guide surgical decision-making in paediatrics. We examined associations between MRI quantification of aortic regurgitation and left ventricular volumetric function and the need for surgical intervention.
Methods:
Forty children and young adults with aortic regurgitation who had undergone cardiac MRI were divided into two groups based on aortic valve surgery (n = 20) or no surgery (n = 20). Ventricular volumetric functional parameters and aortic regurgitant volume and fraction were collected. Differences in MRI parameters between the groups were compared using unpaired t-tests. Receiver operating characteristic analysis identified MRI cut-off values with discriminatory ability towards primary end point of surgery (area under the curve > 0.7).
Results:
Patients who underwent surgery had significantly larger ventricular volumes and aortic regurgitant fraction than those without surgery. Aortic regurgitant fraction and volume had the highest discriminatory power (0.93 and 0.92, respectively) between the two groups, followed by indexed left ventricular volumes (end-diastolic volume 0.85 and end-systolic volume 0.89).
Conclusions:
Current guidelines for surgical intervention in children with chronic aortic regurgitation are limited. Our findings suggest potential MRI-based threshold values that may aid in surgical decision-making and highlight the need future research for aortic valve surgery in children with chronic aortic regurgitation.
The increase in activities related to unmanned aircraft systems and the implementation of this new ecosystem have introduced new hazards, impacting the operational safety of air traffic, particularly near airports, creating risks and disruptions in the flow of aircraft. The establishment of airspace for unmanned traffic management has required the integration of this new airspace with the existing one, bringing the potential for issues from this integration. A method was identified as needed to guide the detection of hazards posed to air traffic control activities and the consequent implementation of required mitigation measures. The aim of this work is to propose a framework for identifying hazards introduced to air traffic control, with a view to ensure the safe transition of this process. The method involved consulting air traffic operational safety specialists via a questionnaire, presenting the hazards highlighted in the literature concerning the integration of new airspace concepts within air traffic control activities. The results, obtained through a Delphi consultation, were analysed based on the most frequently assigned scores (mode) to reflect expert consensus. The results were organised into the proposed framework, establishing a guide to risk management activities aimed at implementing the change. The resulting structure was re-submitted to specialists and validated based on the Delphi method. Contributions to society include a guide for this process and potential future implementations, while the literature gap was addressed by adding knowledge to the scientific process.
According to what I call the Probabilistic View, absence of evidence is evidence of absence when finding evidence is highly expected. However, this view fails to make sense of the practice of using absence of evidence in the paleosciences, where finding evidence is typically not highly expected. Using a case from paleogeology, I offer a novel account of when absence of evidence should be evidence of absence, which I call the Pragmatic View: Appeals to absence of evidence as evidence of absence are warranted because they offer a scaffold to investigate auxiliary hypotheses related to the hypothesis in question.