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We report the dynamics of a droplet levitated in a multi-emitter, single-axis acoustic levitator. The deformation and atomisation behaviour of the droplet in the acoustic field displays myriad complex phenomena, in a series of events. These include the primary breakup of the droplet, wherein it exhibits stable levitation, deformation, sheet formation and equatorial atomisation, followed by its secondary breakup, which could be of various types such as umbrella, bag, bubble or multi-stage breakup. A large number of tiny atomised droplets, formed as a result of the primary and secondary breakup, can remain levitated in the acoustic levitator and exhibit aggregation and coalescence. The visualisation of the interfacial instabilities on the surface of the liquid sheet using both side- and top-view imaging is presented. An approximate size distribution of the atomised droplets is also provided. The stable levitation of the droplet is due to a balance of acoustic and gravitational forces while the resulting ellipsoidal shape of the droplet is a consequence of the balance of the deforming acoustic force and the restoring capillary force. Stronger acoustic forces can no longer be balanced by capillary forces, resulting in a highly flattened droplet, with a thin liquid sheet at the edge (equatorial region). The thinning of the sheet is caused by the differential acceleration induced by the increasing pressure difference between the poles and the equator as the sheet deforms. When the sheet thickness reduces to of the order of a few microns, Faraday waves develop at the thinnest region (preceding the rim), which causes the generation of tiny-sized droplets that are ejected perpendicular to the sheet. The corresponding hole formation results in a perforated sheet that causes the detachment of the annular rim, which breaks due to Rayleigh–Plateau (RP) instability. The radial ligaments generated in the sheet, possibly due to Rayleigh–Taylor (RT) instability, break into droplets of different sizes. The secondary breakup exhibits Weber number dependency and includes umbrella, bag, bubble or multi-stage types, ultimately resulting in the complete atomisation of the droplets. Both the primary and the secondary breakup of the droplet involve interfacial instabilities such as Faraday, Kelvin–Helmholtz, RT and RP and are well supported by visual evidence.
Bounds on heat transfer have been the subject of previous studies concerning convection in the Boussinesq approximation: in the Rayleigh–Bénard configuration, the first result obtained by Howard (J. Fluid Mech., vol. 17, issue 3, 1963, pp. 405–432) states that the dimensionless heat flux $\textit {Nu}$ carried out by convection is such that $\textit {Nu} < (3/64 \ Ra)^{1/2}$ for large values of the Rayleigh number $Ra$, independently of the Prandtl number $Pr$. This is still the best-known upper bound, only with the prefactor improved to $\textit {Nu} -1 < 0.02634 \ Ra^{1/2}$ by Plasting & Kerswell (J. Fluid Mech., vol. 477, 2003, pp. 363–379). In the present paper, this result is extended to compressible convection. An upper bound is obtained for the anelastic liquid approximation, which is similar to an anelastic model used in astrophysics based on a turbulent diffusivity for entropy. The anelastic bound is still scaling as $Ra^{1/2}$, independently of $Pr$, but depends on the dissipation number $\mathcal {D}$ and on the equation of state. For monatomic gases and large Rayleigh numbers, the bound is $\textit {Nu} < 25.8\, Ra^{{1}/{2}} / (1-\mathcal {D}/2 )^{{5}/{2}}$.
Flows over a disc are studied in a wind tunnel over incidence angles between $0^\circ \text { and }36^\circ$, a Reynolds number of $2.7 \times 10^4$ and rotational speed ratios of $0\unicode{x2013}10$. Smoke-wire visualization, particle image velocimetry and hot-film anemometry are employed. Two vortex shedding modes originating from the upstream surface of the disc are observed. The first is dominant at incidence angles up to ${\sim }21^\circ$. Beyond $21^\circ$, the second mode dominates. It appears as a soliton on the vortices and has a shedding frequency nearly twice that of the first at the highest incidence angle. The Strouhal number monotonically increases with incidence angle from approximately 0.2 to 0.4. Spectral analysis of the hot-film measurements confirms the findings from flow visualization experiments. Flows over the spinning disc generally mimic the stationary disc flows; however, centrifugal forces lead to cross-stream instability features that may be attributed to spiral wave instabilities intrinsic to the boundary layers in rotating flows. Velocity measurements are used to construct streamline patterns to compare with the smoke streaklines. The unsteadiness of the flows results in large variances. Mean strain rates are extracted from velocity data, where the fixed disc case at normal incidence compares well with theoretical predictions. The unsteady boundary layer thickness over the fixed disc, however, is approximately twice that predicted by theory for steady flow, stemming from the dominance of large unsteady vortices. Limited comparisons are made of the Strouhal numbers from experiments and numerical calculations in the literature.
In this paper, we study random walks on groups that contain superlinear-divergent geodesics, in the line of thoughts of Goldsborough and Sisto. The existence of a superlinear-divergent geodesic is a quasi-isometry invariant which allows us to execute Gouëzel’s pivoting technique. We develop the theory of superlinear divergence and establish a central limit theorem for random walks on these groups.
Nancy Pelosi makes history. She was the first woman elected to a high-ranking position in the US House of Representatives when she became the Democratic Whip in 2001. She made more history as the first female Democratic Leader in 2003, and first woman elected as Speaker of the House in 2007. She made history by remaining the Democratic Leader even after losing the House majority. Pelosi made history yet again when she was again elected Speaker in 2019, joining Sam Rayburn as the only House leader to lose and then regain the Speakership.
The dimensional transition in turbulent jets of a shear-thinning fluid is studied via direct numerical simulations. Our findings reveal that under vertical confinement, the flow exhibits a unique mixed-dimensional (or 2.5-dimensional) state, where large-scale two-dimensional and small-scale three-dimensional structures coexist. This transition from three-dimensional turbulence near the inlet to two-dimensional dynamics downstream is dictated by the level of confinement: weak confinement guarantees turbulence to remain three-dimensional, whereas strong confinement forces the transition to two dimensions; the mixed-dimensional state is observed for moderate confinement and it emerges as soon as flow scales are larger than the vertical length. In this scenario, we observed that the mixed-dimensional state is an overall more energetic state, and it shows a multi-cascade process, where the direct cascade of energy at small scales and the direct cascade of enstrophy at large scales coexist. The results provide insights into the complex dynamics of confined turbulent flows, relevant in both natural and industrial settings.
In this article, I carry out an in-depth conceptualization of right-to-development governance to illustrate how, as a rights-based model suited to redressing the challenges that have held Africa back over the decades, it can leverage and accelerate the processes for development on the continent. I do so to provide clarity on the deficits in the understanding of the right to development and the dilemma of its implementation in Africa. Through a theoretical and qualitative socio-legal analysis, I frame the argument that Africa's development setbacks are largely generated and sustained by the lack of an operational model that can drive transformation on the continent. Besides having evolved as a claimable human right, the right to development is equally conceived as a model or paradigm for development which is yet to be fully explored to inform development thinking and practice on the continent, and thus enable shared prosperity and improved quality of life and standards of living for the peoples of Africa. The proposed right-to-development governance model is appropriately theorized in this article to provide the basis for its operationalization, which, as explained, entails a nuanced blend of nominal capitalism, communitarian socialism and contemporary culturalism.
One of the most enduring criticisms of papal infallibility is that it seems to set the pope apart from the Church. Much has already been done to correct this impression, but the current ‘synodal moment’ offers a unique opportunity to substantially further this ecclesiological integration. Along such lines, the present article first proposes that the teachings on infallibility in Lumen gentium be read through the chapter on the People of God (LG25 through LG12), thereby treating the pope as a member of the faithful and drawing out the charismatic dimension of infallibility. The article then pivots to exploring the widely overlooked Eastern Catholic reception of Vatican I. Specifically, it details the dogmatic importance of a clause added to Pastor aeternus by two patriarchs as part of their conditional acceptance – something drawing from a deeper tradition of synodal examination of papal teaching. These two sections converge to reveal a more synodal infallibility at the level of initial discernment and reception. More so, these genuinely synodal elements of papal infallibility are discovered as existing within the previous tradition. Elements that, going forward, can fruitfully be given a new hermeneutical priority.
Phytoplasmas are phloem-limited bacteria that are primarily transmitted by hemipteran insects and are emerging threats to Camptotheca acuminata Decne plants due to their associations with a witches’ broom disease. Despite numerous studies, there has been no report on insect transmission of phytoplasma among C. acuminata. Here, transmission characteristics of the leafhopper, Empoasca paraparvipenis Zhang and Liu, 2008 and the phytoplasma in plant leaves through PCR quantification are described. The interaction between C. acuminata-phytoplasma and insect vectors was examined by analysing the impact on the life characteristics and progeny population in a temperature-dependent manner. Phytoplasma-infected C. acuminata plant exhibited symptoms including shorter internodes, weak and clustered branches, shrunken and yellowed leaves, and red leaf margins. The acquisition and transmission time of bacterial-infected third-instar nymphs of insect vectors were 10 (11.11%) and 30 min (33.33%), respectively. A single insect vector can infect a plant after 72 h of feeding, and the incidence rate of disease increases with the number of insects following 11–100% from single to 20 insects. The development time of the infected insect vectors (1–3 instars) was significantly shorter than that of the healthy insects, and the development duration of instar individuals was longer. In progeny populations, the higher the phytoplasma concentration (88–0% for 1–5 instars nymph, female and male adults), the shorter the development time and the longer the adult lifetime (both male and female). These findings provided research evidence of phytoplasma transmission by insect vectors; however, further investigation of the mechanisms for prevention and management of phytoplasma diseases is needed.
Appropriate Dispute Resolution (ADR) is rooted in Africa. However, this is not reflected in scholarship and practice. The last few decades have witnessed the supposed introduction of ADR in Africa, masquerading as an innovation imported from the USA and aiming to extend access to justice. This is a pure revisionism. While African communities rely on ADR to solve disputes, ADR epistemology has not developed in its scientific form. Hence, there is a dearth of literature on what emic unadulterated justice would look like in Africa. This article seeks to provide a framework for how to think about ADR in Africa by presenting five normative conceptions that are latent in African ADR: dispute avoidance; reconciliation; all-inclusive justice; consensus building; and matching disputes to the best process.
The dominance of the Abrahamic tradition in contemporary analytic philosophy of religion has led some to call for greater exploration of alternatives to the traditional conception of God, such as Pantheism, Ultimism, and Axiarchism. While we think this call for alternatives is important, we go in a different direction. Rather than explore and defend alternative conceptions of God, we defend a range of fairly traditional but non-religious conceptions of God. This range of views, from deism to philosophical theism, enjoys a variety of benefits over its religious competitors and deserves greater attention.
Coffee is one of the most known and consumed beverages worldwide. Only three species are used in commercial coffee production, that is, Coffea arabica L. (Arabica coffee), Coffea canephora Pierre ex A. Froehner (Robusta coffee) and Coffea liberica Hiern (Excelsa coffee). The world population consumes approximately two billion cups of coffee per day, making it an important commercial resource of bioactive compounds in world markets. High interest in coffee consumption described in the literature is due not only to its organoleptic properties (for example, desirable bitterness, amount of flavours and aromas) but also to its ability to stimulate the central nervous system.
It is now known that there are more than 1000 compounds in coffee beverages, several of which have a bioactive activity. Recent studies show that consuming three to four cups of coffee per day, that is, moderate consumption according to the European Food Safety Authority, may be beneficial for health.
The main objective of the proposed review is to provide a comprehensive overview of bioactive compounds in coffee and other caffeine-containing beverages and their effects on neurodegenerative proteinopathies.
We prove the existence of a vector-valued cusp form for the full modular group for which the nth derivative of its L-function does not vanish under certain conditions. As an application, we generalize our result to Kohnen’s plus space and prove an analogous result for Jacobi forms.
This paper presents the design and implementation of a broadband down-converter system using the AWR (Advancing the Wireless Revolution) modeling and Microwave Office tool. The radio frequency (RF) signal coming to the antenna interface requires a frequency down-converter to be lowered to the intermediate frequency (IF) band. It includes mixing blocks, oscillators, amplifiers, step attenuators, isolators, and filters. The input frequency band (RF) is 8250 ± 250 MHz, while the output frequency (IF) band is 720 ± 200 MHz. The gain dynamic range of the circuit is expanded through the use of digital attenuators. It is a superheterodyne down-conversion circuit, combining the IF band to produce the desired RF spectrum in one pass. Two phase-locked oscillators are used at the local oscillator port of the mixer, one providing a single frequency, while the other has a programmable frequency synthesizer with 1 MHz steps in the frequency range from 7280 to 7780 MHz.
The formation mechanism for the stopping vortex ring (SVR) and its effects on the development of starting jets have been systematically investigated. The radial inward flow near the nozzle exit, arising from the pressure difference caused by the deceleration of starting jets, is considered to be the main contributing factor to the formation of the SVR. The formation process can generally be divided into (i) the rapid accumulation stage ($t_d^*\leq 1$) and (ii) the development stage ($t_d^*>1$), where $t_d^*$ is the formation time defined by the duration of the deceleration stage. For starting jets with different $(L/D)_d$, the final circulation value and circulation growth rate of the SVR can be scaled by $[(L/D)_d]^{-0.5}$ and $[(L/D)_d]^{-1.5}$, respectively. Here $(L/D)_d$ represents the stroke ratio during the deceleration stage. Analysing the temporal evolution of fluid parcels in the vicinity of the nozzle exit reveals that SVR entrains fluid from both inside and outside of the nozzle. Additionally, the influence of the SVR on the leading vortex ring and the trailing jet has been examined, with particular attention to its effects on the propulsive performance of the starting jet. The SVR affects the profiles of axial velocity and gauge pressure at the nozzle exit, thereby enhancing the generation of total thrust during the deceleration stage. Analysis has shown that depending on the deceleration rate, SVR can enhance the average velocity thrust by at least $10\,\%$ and compensate for up to a $60\,\%$ reduction in pressure thrust due to deceleration.
Information related to the climate, sowing time, harvest, and crop development is essential for defining appropriate strategies for agricultural activities, which helps both producers and responsible bodies. Paraná, the second largest soybean producer in Brazil, has high climatic variability, which greatly influences planting, harvesting, and crop productivity periods. Therefore, the objective of this study was to regionalize the state of Paraná, considering decennial metrics associated with climate variables and the enhanced vegetation index (EVI) during the soybean cycle. Individual and global analyses of these metrics were conducted performed using multivariate techniques. These analyses were carried out in agricultural scenarios with low, medium, and high precipitation, corresponding to harvest years 2011/2012, 2013/2014, and 2015/2016, respectively. The results obtained from the scores of the retained factors and the cluster analysis were the profile of the groups, with Group 1 presenting more favourable climatic and agronomic conditions for the development of soybean crops for the three harvest years. The opposite occurred for Groups 2 (2011/2012 and 2013/2014) and Group 3 (2015/2016). During the soybean reproductive phases (R2 – R5), precipitation values were inadequate, especially for Group 2 (2011/2012 and 2013/2014) with high water deficit, resulting in a drop in soybean productivity. The climatic and agronomic regionalization of Paraná made it possible to identify the regions most suitable for growing soybeans, the effect of climatic conditions on phenological stages, and the variability of soybean productivity in the three harvest years.
This article looks at the gender regime of the governing Justice and Development Party (Adalet ve Kalkınma Partisi; AKP) in Turkey through the double lenses of “gender ideology” and moral panics. It traces the itinerary along which “gender ideology” as a reactionary discourse has traveled through a landscape stretching from the Vatican to Turkey. This trajectory places the AKP’s gender perspective and policies within a larger right-wing populist rhetoric of transnational fundamentalism which claims gender is an ideology. The “gender ideology” discourse of the AKP is maintained through a constant sense of crisis which reveals itself in moments of moral panics. The article specifically takes the period of 2019–2020 where such a moment of moral panic was heightened and examines this specific period through an analysis of public speeches of political figures, newspaper articles, and other published materials on the issue. The article shows how this fundamentalist discourse of “gender ideology” and its concomitant strategy of moral panics built an oppressive political environment for women and LGBTI+ people in Turkey and paved the road to the country’s withdrawal from the İstanbul Convention in 2021.