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where $\Omega \subset \mathbb {R}^{3}$ is a bounded domain, either convex or with $\mathcal {C}^{1,1}$ boundary, $\nu$ is the exterior normal, $\lambda <0$ is a real parameter, $2^{\ast }_{\alpha }=3+\alpha$ with $0<\alpha <3$ is the upper critical exponent due to the Hardy–Littlewood–Sobolev inequality. By introducing some suitable Coulomb spaces involving curl operator $W^{\alpha,2^{\ast }_{\alpha }}_{0}(\mathrm {curl};\Omega )$, we are able to obtain the ground state solutions of the curl–curl equation via the method of constraining Nehari–Pankov manifold. Correspondingly, some sharp constants of the Sobolev-like inequalities with curl operator are obtained by a nonlocal version of the concentration–compactness principle.
The crystal structure of ractopamine hydrochloride has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Ractopamine hydrochloride crystallizes in space group Pbca (#61) with a = 38.5871(49), b = 10.7691(3), c = 8.4003(2) Å, V = 3490.75(41) Å3, and Z = 8. The ractopamine cation contains two chiral centers, and the sample consists of a mixture of the S,S/R,R/S,R and R,S forms. Models for the two diastereomers S,S and S,R were refined, and yielded equivalent residuals, but the S,R form is significantly lower in energy. The crystal structure consists of layers of molecules parallel to the bc-plane. In each structure one of the H atoms on the protonated N atom acts as a donor in a strong discrete N–H⋯Cl hydrogen bond. Hydroxyl groups act as donors in O–H⋯Cl and O–H⋯O hydrogen bonds. Both the classical and C–H⋯Cl and C–H⋯O hydrogen bonds differ between the forms, helping to explain the large microstrain observed for the sample. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™ (PDF®).
Cavitation inception originates from nuclei in a liquid. This paper proposes a Gibbs free energy approach that provides a smooth transition from homogeneous to heterogeneous nucleation when gas is present. The impact of gas content on nucleation is explored. It is found that the gas content stabilises nuclei, a phenomenon not present in pure liquid–vapour systems. This reduces the energy barrier over that required to nucleate a vapour bubble. Different gas saturation levels are studied. Gas content can significantly reduce the energy barrier required for nucleation, and under certain circumstances eliminate it. An analytic solution for the critical radius and activation energy is obtained that accounts for gas content. The classical Blake radius is recovered as a limiting case. The hysteresis between incipience and desinence is explained using the asymmetry observed in the critical radii. The solution is used to obtain the initial bubble radius, given a critical pressure condition in cavitation susceptibility meter experiments. The relationship between initial bubble diameter and critical pressure is described by an analytic solution that accounts for gas content. A model for the derivative of the cumulative nuclei histogram with respect to bubble diameter is proposed. An analytic expression is obtained that shows good agreement with decades worth of experimental data compiled by Khoo et al. (Exp. Fluids, vol. 61, issue 2, 2020, pp. 1–20) from ocean to water tunnels. The expression recovers the $-4$ power law that is observed experimentally.
Hegel's philosophy has been a fundamental reference point for a broad network of mid-twentieth century anticolonial thinkers and activists, a major inspiration for figures such as W. E. B. Du Bois, Frantz Fanon, C. L. R. James, Martin Luther King Jr. and Angela Davis, among others. James's Notes on Dialectics (1948) constitutes one of the most significant textual engagements with Hegel from within that internationalist tradition. Even though James considered Notes to be his most important work and one of his lasting contributions to Marxist theory, it remains the least read and studied of his books. In comparison to the abovementioned thinkers, all of whom drew inspiration from Hegel's social and political philosophy, in his monograph, James turns instead to Hegel's most difficult text, the Science of Logic, as the true locus of Hegel's critical theory. Situating James's study within the Marxist philosophical tradition, this essay explores how James interprets, appropriates and makes use of Hegel's dialectic.
This study assessed postprandial plasma aminoacidemia, glycemia, insulinemia and appetite responses to ingestion of a novel salmon-derived protein peptide (Salmon PP) compared with milk protein isolate (Milk PI). In a randomised, participant-blind crossover design, eleven healthy adults (M = 5, F = 6; mean ± sd age: 22 ± 3 years; BMI: 24 ± 3 kg/m2) ingested 0·3 g/kg/body mass of Salmon PP or Milk PI. Arterialised blood samples were collected whilst fasted and over a 240-min postprandial period. Appetite sensations were measured via visual analogue scales. An ad libitum buffet-style test meal was administered after each trial. The incremental AUC (iAUC) plasma essential amino acid (EAA) response was similar between Salmon PP and Milk PI. The iAUC plasma leucine response was significantly greater following Milk PI ingestion (P < 0·001), whereas temporal and iAUC plasma total amino acid (P = 0·001), non-essential amino acid (P = 0·002), glycine (P = 0·0025) and hydroxyproline (P < 0·001) responses were greater following Salmon PP ingestion. Plasma insulin increased similarly above post-absorptive values following Salmon PP and Milk PI ingestion, whilst plasma glucose was largely unaltered. Indices of appetite were similarly altered following Salmon PP and Milk PI ingestion, and total energy and macronutrient intake during the ad libitum meal was similar between Salmon PP and Milk PI. The postprandial plasma EAA, glycine, proline and hydroxyproline response to Salmon PP ingestion suggest this novel protein source could support muscle and possibly connective tissue adaptive remodelling, which warrants further investigation, particularly as the plasma leucine response to Salmon PP ingestion was inferior to Milk PI.
We propose generating functions, $\textrm {RGF}_p(x)$, for the quotients of numerical semigroups which are related to the Sylvester denumerant. Using MacMahon’s partition analysis, we can obtain $\textrm {RGF}_p(x)$ by extracting the constant term of a rational function. We use $\textrm {RGF}_p(x)$ to give a system of generators for the quotient of the numerical semigroup $\langle a_1,a_2,a_3\rangle $ by p for a small positive integer p, and we characterise the generators of ${\langle A\rangle }/{p}$ for a general numerical semigroup A and any positive integer p.
Materials in a high radioactive environment undergo structural changes. X-ray diffraction (XRD) is commonly used to study the micro-structural changes of such materials. Therefore, a safe procedure is required for the preparation of specimens. In this paper, a simple methodology for the preparation of radioactive powder specimens to be analyzed in a non-nuclearized laboratory diffractometer is presented. The process is carried out inside a shielded glove box, where the milling of the radioactive sample and specimen preparation occurs. Minimum amount of sample is required (<20 mg), which is drop-casted on a polyether ether ketone (PEEK) foil and glue-sealed inside a disposable plastic holder for a safe handling of the specimen. One example using neutron-irradiated granite is shown, where unit-cell parameters and crystal density of the main phases were calculated. The developed methodology represents an easy and affordable way to study neutron irradiated materials with low activity at laboratory scale.
Tonsillectomy is a common procedure performed nationally. The personal protective equipment and surgical gowning practices used during this procedure vary widely. We compiled a survey of ENT specialists to gain a national opinion about gowning in tonsillectomy with the aim of determining whether we could make it more environmentally friendly whilst maintaining the highest safety standards.
Method
We developed a nine-question survey that was piloted prior to final implementation. The questionnaire was sent to senior registrars and consultant otolaryngologists in the UK.
Results
The survey was completed by a total of 63 ENT specialists. It was found that 82.54 per cent of clinicians would consider wearing a reusable gown that would be sterilised between each procedure.
Conclusion
Our survey suggests most ENT clinicians would consider using a more environmentally friendly surgical gown and some may even consider wearing no gown at all, although many are understandably concerned about the transmission of infection or blood splatter.
When a fluid system is subjected to an acoustic wave (or another periodic actuation), the response of the fluid is not purely periodic, but is rather characterized by the combination of a periodic flow and a steady Stokes drift component, where the former is, in many cases, an acoustic wave and the latter is commonly referred to as acoustic streaming. Classical theories of acoustic streaming have focused on slow acoustic streaming, where the periodic flow is the leading-order flow, and is insensitive to the steady flow component which appears as a small correction and is characterized by a small hydrodynamic Reynolds number. In contrast, Dubrovski et al. (J. Fluid Mech. vol. 975, 2023, A4) tackle the fast acoustic streaming regime – conceived by Zarembo (Acoustic streaming. In High-Intensity Ultrasonic Fields, 1971, pp. 135–199. Springer) approximately fifty years ago – where both the periodic and steady flow components are of a similar order of magnitude such that the periodic flow both supports and is simultaneously impacted by the steady flow. They present a novel theoretical framework that accounts for the convection of momentum both within and between the periodic and steady flow to extend slow-streaming equations to the case of steady flow with arbitrary hydrodynamic Reynolds number. They leverage a scaling analysis of the resulting system of equations and a case study to demonstrate the compatibility of their equations with slow streaming theories and highlight the distinctive features of fast streaming.
The traditional ground collision avoidance system (GCAS) makes avoidance decisions based on predicted collision time, without considering the impact of terrain environment and dynamic changes in load factor on avoidance decisions. This increases the risk of ground collisions for the aircraft. To solve the problem, a GCAS with multi-trajectory risk assessment and decision function is proposed. Firstly, a variety of predicted flight avoidance trajectories are established within the final manoeuvering capability of the aircraft. Secondly, for each predicted trajectory, the uncertain length between adjacent prediction points is used to construct a rectangular distance bin, and the terrain data below the avoided trajectory is extracted. Finally, the regret theory is used to establish a multi-attribute avoidance decision model to evaluate and prioritise the risk of collision avoidance trajectories, to provide effective collision avoidance decision for pilots. The algorithm is tested and verified with real digital elevation model and simulated flight data, and compared with traditional GCAS. Simulation results show that the proposed algorithm can comprehensively consider manoeuvering performance and threatening terrain, and provide safe and effective avoidance decisions for pilots.
Intracellular levels of glutathione, the major mammalian antioxidant, are reported to decline with age in several species. To understand whether ageing affects circulating glutathione levels in cats, blood was sampled from two age groups, < 3 years and > 9 years. Further, to determine whether dietary supplementation with glutathione precursor glycine (GLY) affects glutathione concentrations in senior cats (> 8 years), a series of free GLY inclusion level dry diets were fed. Subsequently, a 16-week GLY feeding study was conducted in senior cats (> 7 years), measuring glutathione, and markers of oxidative stress. Whole blood and erythrocyte total, oxidised and reduced glutathione levels were significantly decreased in senior cats, compared with their younger counterparts (P ≤ 0·02). The inclusion level study identified 1·5 % free GLY for the subsequent dry diet feeding study. Significant increases in erythrocyte total and reduced glutathione were observed between senior cats fed supplemented and control diets at 4 weeks (P ≤ 0·03; maximum difference of 1·23 µM). Oxidative stress markers were also significantly different between groups at 8 (P = 0·004; difference of 0·68 nG/ml in 8-hydroxy-2'-deoxyguanosine) and 12 weeks (P ≤ 0·049; maximum difference of 0·62 nG/mG Cr in F2-isoprostane PGF2α). Senior cats have lower circulating glutathione levels compared with younger cats. Feeding senior cats a complete and balanced dry diet supplemented with 1·5 % free GLY for 12 weeks elevated initial erythrocyte glutathione and altered markers of oxidative stress. Dietary supplementation with free GLY provides a potential opportunity to restore age-associated reduction in glutathione in cats.
The structure of Ni(3-amino-4,4′-bipyridine)[Ni(CN)4] (or known as Ni-BpyNH2) in powder form was determined using synchrotron X-ray diffraction and refined using the Rietveld refinement technique (R = 8.8%). The orthorhombic (Cmca) cell parameters were determined to be a = 14.7218(3) Å, b = 22.6615(3) Å, c = 12.3833(3) Å, V = 4131.29(9) Å3, and Z = 8. Ni-BpyNH2 forms a 3-D network, with a 2-D Ni(CN)4 net connecting to each other via the BpyNH2 ligands. There are two independent Ni sites on the net. The 2-D nets are connected to each other via the bonding of the pyridine “N” atom to Ni2. The Ni2 site is of six-fold coordination to N with relatively long Ni2–N distances (average of 2.118 Å) as compared to the four-fold coordinated Ni1–C distances (average of 1.850 Å). The Ni(CN)4 net is arranged in a wave-like fashion. The functional group, –NH2, is disordered and was found to be in the m-position relative to the N atom of the pyridine ring. Instead of having a unique position, N has ¼ site occupancy in each of the four m-positions. The powder reference diffraction pattern for Ni-BpyNH2 was prepared and submitted to the Powder Diffraction File (PDF) at the International Centre of Diffraction Data (ICDD).
A model for the crystal structure of carbadox has been generated and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Carbadox crystallizes in space group P21 (#4) with a = 13.8155(3), b = 21.4662(1), c = 16.3297(3) Å, β = 110.0931(7)°, V = 4548.10(3) Å3, and Z = 16. The crystal structure is characterized by approximately parallel stacking of the eight independent carbadox molecules parallel to the bc-plane. There are two different molecular configurations of the eight carbadox molecules; five are in the lower-energy configuration and three are in a ~10% higher-energy configuration. This arrangement likely achieves the lowest-energy crystalline packing via hydrogen bonding. Hydrogen bonds link the molecules both within and between the planes. Each of the amino groups forms a N–H⋯O hydrogen bond to an oxygen atom of the 1,4-dioxidoquinoxaline ring system of another molecule. The result is four pairs of hydrogen-bonded molecules, which form rings with graph set R2,2(14). Variation in specimen preparation can affect the preferred orientation of particles considerably. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).