We consider the interactions of internal tides (ITs) with a dynamic, rotational and heterogeneous ocean, and spatially varying topography. The IT fields are expanded using vertical modal basis functions, whose amplitudes vary horizontally and temporally. We obtain the evolution equations of modal amplitudes and energy including simultaneous three-way interactions with the mean flow, buoyancy and topography. We apply these equations to a set of idealized and two realistic data-assimilative primitive equation simulations. These simulations reveal that significant interactions of ITs with the background fields occur at topographic features and strong currents, in particular when the scales of the background and ITs are similar. In local hot spots, the new three-way interaction terms, when compared to the total modal conversion, are found to reach up to 10 %–30 % at steep topography and approximately 50 % in the Gulf Stream. We provide a dimensional analysis to guide the diagnosis of such strong interactions. When IT interactions are with a large-scale barotropic current (without topographic effects), our modal energy equation reduces to the conservation of modal wave action under a Wentzel–Kramers–Brillouin consideration. We further derive analytical solutions of the modulation of wavenumber and energy of an IT propagating into a collinear current. For ITs propagating along the flow direction, the wavelength is stretched and the amplitude is reduced, with the degree of modulation determined by $|\,f/\omega _0|$, the ratio of inertial to tidal frequencies. For ITs propagating opposite to the flow direction, a critical value of $|\,f/\omega _0|$ exists, below and above which the waves show remarkably different behaviours. The critical opposing current speed which triggers the wave focusing/blocking phenomenon is obtained and its implication for the propagation and dissipation of ITs is discussed.

Vitamin D (VD) has been reported to play multiple and significant roles in improving pig health via modulating calcium and phosphorus homeostasis, skeletal muscle development and the immune system. Apart from food, photochemical action of 7-dehydrocholesterol in the skin is the main source of this molecule for pigs. The VD from dietary intake or photosynthesized via skin can be absorbed into the liver for hydroxylation, and further hydroxylated into the hormone form of VD (1,25-dihydroxyvitamin D3 or 1,25(OH)2D3) in the kidney. As a sterol hormone, 1,25(OH)2D3 is able to bind with the VD receptor (VDR), and this ligand-receptor complex (VDR/retinoic X receptor) translocates from the cytoplasm into the nucleus to regulate gene expression, thus modulating metabolism. In this review, we summarized the recent studies regarding the non-skeletal health benefits of VD for pigs, and focused on the recent advances in the cellular and molecular mechanisms of VD that affects the immune system and reproductive health. This review provides a reference for future research and application of VD in pigs.

In this paper, we define a family of functionals generalizing the Yang–Mills–Higgs functionals on a closed Riemannian manifold. Then we prove the short-time existence of the corresponding gradient flow by a gauge-fixing technique. The lack of a maximum principle for the higher order operator brings us a lot of inconvenience during the estimates for the Higgs field. We observe that the $L^2$-bound of the Higgs field is enough for energy estimates in four dimensions and we show that, provided the order of derivatives appearing in the higher order Yang–Mills–Higgs functionals is strictly greater than one, solutions to the gradient flow do not hit any finite-time singularities. As for the Yang–Mills–Higgs k-functional with Higgs self-interaction, we show that, provided $\dim (M)<2(k+1)$, for every smooth initial data the associated gradient flow admits long-time existence. The proof depends on local $L^2$-derivative estimates, energy estimates and blow-up analysis.

This article investigates the collective responsibility organizations among boatmen in nineteenth-century Chongqing, when the city became one of the most important metropolises on the southwest Qing frontier. It also introduces two successive turning points in self-organization that were associated with two different classes of boatmen – skippers and sailors. First, in 1803, skippers gained the authority to institutionalize their organizations through their negotiations with the local state regarding official services and service fees. Second, when similar service and fiscal tensions emerged between skippers and sailors in the mid-nineteenth century, the skippers facilitated and supervised the institutionalization of collective responsibility organizations that were run by the sailors themselves. By contextualizing this expansion of collective responsibility organizations within the multilayered interactions between skippers and sailors, this article proposes that the perspective of interclass networks is crucial for deepening the study of state−society interactions, the capital−labor relationship, as well as the tension between imperial integration and regional diversity in early modern China.

To unveil the adaptation of Litopenaeus vannamei to elevated ambient ammonia-N, crustacean hyperglycaemic hormone (CHH) was knocked down to investigate its function in glucose metabolism pathway under ammonia-N exposure. When CHH was silenced, haemolymph glucose increased significantly during 3–6 h, decreased significantly during 12–48 h and recovered to the control groups’ level at 72 h. After CHH knock-down, dopamine (DA) contents reduced significantly during 3–24 h, which recovered after 48 h. Besides, the expressions of guanylyl cyclase (GC) and DA1R in the hepatopancreas decreased significantly, while DA4R increased significantly. Correspondingly, the contents of cyclic AMP (cAMP), cyclic GMP (cGMP) and diacylglycerol (DAG) and the expressions of protein kinase A (PKA), protein kinase G (PKG), AMP active protein kinase α (AMPKα) and AMPKγ were significantly down-regulated, while the levels of protein kinase C (PKC) and AMPKβ were significantly up-regulated. The expressions of cyclic AMP response element-binding protein (CREB) and GLUT2 decreased significantly, while GLUT1 increased significantly. Moreover, glycogen content, glycogen synthase and glycogen phosphorylase activities in hepatopancreas and muscle were significantly increased. Furthermore, the levels of key enzymes hexokinase, pyruvate kinase and phosphofructokinase in glycolysis (GLY), rate-limiting enzymes citrate synthase in tricarboxylic acid and critical enzymes phosphoenolpyruvate carboxykinase, fructose diphosphate and glucose-6-phosphatase in gluconeogenesis (GNG) were significantly decreased in hepatopancreas. These results suggest that CHH affects DA and then they affect their receptors to transmit glucose metabolism signals into the hepatopancreas of L. vannamei under ammonia-N stress. CHH acts on the cGMP-PKG-AMPKα-CREB pathway through GC, and CHH affects DA to influence cAMP-PKA-AMPKγ-CREB and DAG-PKC-AMPKβ-CREB pathways, thereby regulating GLUT, inhibiting glycogen metabolism and promoting GLY and GNG. This study contributes to further understand glucose metabolism mechanism of crustacean in response to environmental stress.

Through ensemble-based data assimilation, we address one of the most notorious difficulties in phase-resolved ocean wave forecast, regarding the deviation of numerical solution from the true surface elevation due to the chaotic nature of and underrepresented physics in the nonlinear wave models. In particular, we develop a coupled approach of the high-order spectral (HOS) method with the ensemble Kalman filter (EnKF), through which the measurement data can be incorporated into the simulation to improve the forecast performance. A unique feature in this coupling is the mismatch between the predictable zone and measurement region, which is accounted for through a special algorithm to modify the analysis equation in EnKF. We test the performance of the new EnKF–HOS method using both synthetic data and real radar measurements. For both cases (though differing in details), it is shown that the new method achieves much higher accuracy than the HOS-only method, and can retain the phase information of an irregular wave field for an arbitrarily long forecast time with sequentially assimilated data.

Koopman decomposition is a nonlinear generalization of eigen-decomposition, and is being increasingly utilized in the analysis of spatio-temporal dynamics. Well-known techniques such as the dynamic mode decomposition (DMD) and its linear variants provide approximations to the Koopman operator, and have been applied extensively in many fluid dynamic problems. Despite being endowed with a richer dictionary of nonlinear observables, nonlinear variants of the DMD, such as extended/kernel dynamic mode decomposition (EDMD/KDMD) are seldom applied to large-scale problems primarily due to the difficulty of discerning the Koopman-invariant subspace from thousands of resulting Koopman eigenmodes. To address this issue, we propose a framework based on a multi-task feature learning to extract the most informative Koopman-invariant subspace by removing redundant and spurious Koopman triplets. In particular, we develop a pruning procedure that penalizes departure from linear evolution. These algorithms can be viewed as sparsity-promoting extensions of EDMD/KDMD. Furthermore, we extend KDMD to a continuous-time setting and show a relationship between the present algorithm, sparsity-promoting DMD and an empirical criterion from the viewpoint of non-convex optimization. The effectiveness of our algorithm is demonstrated on examples ranging from simple dynamical systems to two-dimensional cylinder wake flows at different Reynolds numbers and a three-dimensional turbulent ship-airwake flow. The latter two problems are designed such that very strong nonlinear transients are present, thus requiring an accurate approximation of the Koopman operator. Underlying physical mechanisms are analysed, with an emphasis on characterizing transient dynamics. The results are compared with existing theoretical expositions and numerical approximations.

Automatic generation of high-quality meshes is a base of CAD/CAE systems. The element extraction is a major mesh generation method for its capabilities to generate high-quality meshes around the domain boundary and to control local mesh densities. However, its widespread applications have been inhibited by the difficulties in generating satisfactory meshes in the interior of a domain or even in generating a complete mesh. The element extraction method's primary challenge is to define element extraction rules for achieving high-quality meshes in both the boundary and the interior of a geometric domain with complex shapes. This paper presents a self-learning element extraction system, FreeMesh-S, that can automatically acquire robust and high-quality element extraction rules. Two central components enable the FreeMesh-S: (1) three primitive structures of element extraction rules, which are constructed according to boundary patterns of any geometric boundary shapes; (2) a novel self-learning schema, which is used to automatically define and refine the relationships between the parameters included in the element extraction rules, by combining an Advantage Actor-Critic (A2C) reinforcement learning network and a Feedforward Neural Network (FNN). The A2C network learns the mesh generation process through random mesh element extraction actions using element quality as a reward signal and produces high-quality elements over time. The FNN takes the mesh generated from the A2C as samples to train itself for the fast generation of high-quality elements. FreeMesh-S is demonstrated by its application to two-dimensional quad mesh generation. The meshing performance of FreeMesh-S is compared with three existing popular approaches on ten pre-defined domain boundaries. The experimental results show that even with much less domain knowledge required to develop the algorithm, FreeMesh-S outperforms those three approaches in essential indices. FreeMesh-S significantly reduces the time and expertise needed to create high-quality mesh generation algorithms.

Extreme cavitation scenarios, such as water column separations in hydraulic systems during transient processes caused by large cavitation bubbles, can lead to catastrophic destruction. In the present paper, we study the onset criteria and dynamics of large cavitation bubbles in a tube. A new cavitation number $Ca_2 = {l^*}^{-1} Ca_0$ is proposed to describe the maximum length $L_{max}$ of the cavitation bubble, where $l^*$ is a non-dimensional length of the water column indicating its slenderness, and $Ca_0$ is the classic cavitation number. Combined with the onset criteria for acceleration-induced cavitation ($Ca_1<1$, Pan et al., Proc. Natl Acad. Sci. USA, vol. 114, 2017, pp. 8470–8474), we show that the occurrence of large cylindrical cavitation bubbles requires both $Ca_2<1$ and $Ca_1<1$ simultaneously. We also establish a Rayleigh-type model for the dynamics of large cavitation bubbles in a tube. The bubbles collapse at a finite end speed, and the time from the maximum bubble size to collapse is $T_c=\sqrt {2}\sqrt {lL_{max}}\sqrt {{\rho }/{p_\infty }}$, where $l$ is the length of the water column, $L_{max}$ is the maximum bubble length, $\rho$ is the liquid density and $p_{\infty }$ is the reference pressure in the far field. The analytical results are validated against systematic experiments using a modified ‘tube-arrest’ apparatus, which can decouple acceleration and velocity. The results in the current work can guide design and operation of hydraulic systems encountering transient processes.

ABSTRACT IMPACT: This poster will demonstrate how a community issue from a CTSI Community Advisory Board member organization initiated a collaborative, community-engaged project to identify priority areas of concern and culturally appropriate mitigation strategies. OBJECTIVES/GOALS: Little is known about the health and psychosocial impact of construction on older adults living near construction sites. We applied a mixed methods approach to identify evidence-based strategies to mitigate community prioritized health and psychosocial concerns related to long-term construction on older adults in NYC’s Manhattan Chinatown. METHODS/STUDY POPULATION: In Chinatown, where approximately 20% of its residents are seniors, many are poor, have a disability, and experience ambulatory difficulties. We used a mixed methods approach including: 1) a high level scoping review of the published literature on the health impact of long-term construction for older adults; 2) key informant interviews with stakeholders; and 3) a two-part community-engaged modified Delphi process to identify priority topic areas related to construction and older adults and evidence-informed, culturally-relevant mitigation strategies. Using priority areas identified through the modified Delphi process, we conducted a literature review on the health and psychosocial impact of construction on older adults. RESULTS/ANTICIPATED RESULTS: We identified five priority topics: construction site emissions; noise; outdoor nocturnal lighting; neighborhood changes; and relocation. Long-term construction is associated with environmental and psychosocial consequences with greater negative impacts on vulnerable populations. Current NYC mitigation policies are based on general population and need revisions to consider impacts for the most vulnerable, e.g. older adults and children, to mitigate adverse health outcomes. Findings were shared with City Council members and resulted in enacting specific recommended mitigation strategies, e.g. double paned windows, etc. Seniors are highly susceptible to the effects of air pollution, noise, and environmental changes, with exposure associated with higher morbidity, mortality, and social isolation. DISCUSSION/SIGNIFICANCE OF FINDINGS: Long-term construction may pose serious health implications for seniors residing near construction sites. Standards and guidelines for the general population may not protect them. Community-driven coalitions, like community-academic partnerships, can successfully advance community priorities and inform strategies to protect the elderly.

ABSTRACT IMPACT: This poster will demonstrate how input from a CTSI Community Advisory Board was used to develop a large, annual dissemination event focused on health disparities, health equity, and community engagement. OBJECTIVES/GOALS: The NYU Langone Annual Health Disparities Symposium began in response to the NYU-H+H CTSI’s Community Advisory Board, which expressed a desire to 1) learn about health disparities research at NYU, H+H, and beyond; 2) build connections and interdisciplinary collaborations; 3) support bidirectional dissemination between community and researchers. METHODS/STUDY POPULATION: The annual symposium, a collaboration between NYU Langone’s CTSI, Department of Population Health, Office of Diversity Affairs, and the NYU-CUNY Prevention Research Center, features a keynote, a series of rapid-fire talks, panels on current controversies in population health and the work of the Community Engagement Cores of NYC-based CTSAs, and poster sessions. Each year the event is focused around a specific theme, with the 2020 theme being ‘Research Into Action’. Audience members include faculty, staff, students, health care providers, community health workers, and representatives from community-based organizations, health care facilities, and the NYC Department of Health and Mental Hygiene. For the very first time, the event was held virtually days and CME/CNE credits were provided free of cost. RESULTS/ANTICIPATED RESULTS: The conference explored how institutions have turned research into action, and speakers addressed the ways in which COVID-19 has highlighted structural inequities that have existed across time. 585 attendees participated in the event, with 63 claiming an average of 7.8 hours of continuing education credits. 46 individuals completed the post-event evaluation, with 95% agreeing/strongly agreeing that the symposium increased their awareness of health disparities research taking place at NYU, H+H, and beyond, 91% agreeing/strongly agreeing that they are likely to apply the information learned to their own work, and 91% agreeing/strongly agreeing that the symposium increased their interest in health disparities research. 86% were very/extremely satisfied with the quality of the meeting overall. DISCUSSION/SIGNIFICANCE OF FINDINGS: The 2020 event had the greatest proportion of health care provider attendees (24%), likely due to the opportunity to earn CME/CNE credits. Attendance also grew over the years, from 150 in 2015 to 585 in 2020. This increase is likely due to increased awareness of the event, as well as well as virtual the format, which made it more convenient for attendees.