The role of outflow geometry in the formation of the recirculating bulge region in coastal buoyant outflows

Density-driven coastal currents are a common feature in the world\u27s coastal oceans. These currents may separate from the coastline due to variations in geometry. Past studies have shown that this separation may produce two distinctly different flow states: a continuation of the coastal current, or a recirculating gyre downshelf of, and attached to, the separation point. Laboratory experiments of coastal buoyant outflows (rotationally dominated, buoyancy driven) were undertaken to examine the role of bay geometry on the evolution of the outflow. Experiments were conducted on a rotating turntable in relatively deep water (such that the buoyant layer depth was much less than the total ocean depth). The geometry of the bay-exit was varied, both in exit angle () and in radius of curvature (rc). The width of the bay was varied such that the bay exit Kelvin number (a ratio between the width of the bay exit and the internal Rossby deformation radius) was order 1 for all experiments. A recirculating bulge (a large, anticyclonic gyre joining the coastal current to the buoyant source) was occasionally observed to form. Results are compared to the Bormans and Garrett (1989) hypothesis: this hypothesis is found to explain a portion of the results only. Geometrical arguments are presented that build upon the Bormans and Garrett hypothesis that parameterizes the magnitude of the flow separation between the buoyant fluid and the exit. A separation ratio, Γ, is defined as a ratio between the inertial turning radius of the flow and the maximum offshore distance between the separated flow and the coast. A recirculating bulge was observed to form for flows with values of Γ \u3e 0.5. The separation ratio, Γ, is shown to be equivalent to the impact angle, Φ, of the buoyant fluid re-encountering the wall. The impact angle governs the upshelf and downshelf volume flux of the impacting fluid: recirculating bulge formation is found to occur when at least 50% of the source volume flux returns to the source region. This is equivalent to an impact angle greater than or equal to 60-degrees

The characteristics of the recirculating bulge region in coastal buoyant outflows

A relatively large recirculating gyre, or bulge (anticyclonic buoyant lens) region attached to the source has been observed to occur in some numerical simulations and in some oceanic outflows. The purpose of this paper is to determine the dynamics of such recirculating bulge regions. Laboratory experiments were conducted for the purpose of examining the characteristics, evolution, and impact of a recirculating bulge in a coastal buoyant outflow. All experiments were performed such that the buoyant layer was thin compared to the total water depth, and the width of the bay exit was approximately equal to the internal Rossby deformation radius of the buoyant outflow. The geometry of the bay-exit (radius of curvature and exit angle) was varied in order to produce experiments with recirculating bulge formation, and experiments without. Measurements of the density and velocity fields were undertaken. The dimensions of the recirculating bulge were found to evolve identically (when appropriately scaled) for all experiments in which such a bulge formed, regardless of bay-exit geometry. When recirculating bulges formed, it was determined that the freshwater storage within the bulge was approximately 60 -70% of the source freshwater flux. The impact on the attached coastal current downshelf of the recirculating bulge was found to be significant: the width, length, and velocities of such attached coastal currents were much reduced in comparison to coastal currents that evolved in the absence of a recirculating bulge. Growth rates of the bulge were measured with time: the recirculating bulge was found to grow radially as ~t2/5 and vertically as ~t1/5. Baroclinic instabilities were observed in the recirculating bulge. The instabilities evolved as multiple rotating cores within the larger anticyclonic gyre. The presence of the instabilities in the recirculating bulge may account for its relatively large radial growth but weak vertical growth

The role of Kelvin Number on bulge formation from estuarine buoyant outflows

Abstract This investigation examines the influence of the Kelvin number (K) and fractional depth (h/D) on bulge formation from buoyant outflows from an estuary or strait perpendicular to the coastline. Here K=W/R is the ratio of the width (W) at the mouth of the estuary to the deformation radius (R), and h and D are the buoyant layer and ambient ocean depths, respectively. Measurements of velocity and lateral shear (≈ relative vorticity ζ) at the baymouth are reported for experiments on a flat-bottomed rotating turntable. The form of the velocity profile across the mouth depends on the value of K. The buoyant outflow flows across the entire width of the estuary for narrow estuaries (i.e., K≤1). In contrast, for wide estuaries (K>2), dense oceanic water inflows on the left and the buoyant waters outflow on the right (looking seaward). Velocity profiles of the inflowing oceanic waters are laterally uniform with velocities (V/C≈−0.4), whereas velocity profiles of the outflowing buoyant waters are laterally sheared with peak velocities of V/C≈1.0 at the right hand exit. The flow pathways when bulges form comprises an anticyclonic turn offshore of the mouth and a downshelf propagating coastal current. Anticyclonic bulges form for surface-advected outflows h/D<0.25. Anticyclonic bulges do not form for sufficiently large magnitudes of non-dimensional relative vorticity ζ/f (>0.4), and an additional flow pathway is that buoyant waters recirculate back cyclonically into the estuary at the left-hand (upshelf) side of the estuary. The offshore extent of buoyant waters associated with this cyclonic recirculation can be as large as 7R

Energetics in Delaware Bay: Comparison of two box models with observations

A corrected version of an unstratified box model of potential energy anomaly , initially developed by Garvine and Whitney (2006), and a new two-layer box model that allows for stratified and well-mixed conditions are applied to Delaware Bay. The models are applied for the Garvine and Whitney (2006) 1988-1994 study period and in Spring 2003; however, only model results of potential energy anomaly from the latter period are compared to in situ observations obtained outside the bay mouth. Unstratified model results for the two study periods reveal that the river discharge (Ω1) is the largest potential energy anomaly contributor. This term is closely followed (but with opposite sign) by the coastal current efflux term (Ω2). For the two-layer model the largest contributor is the dense inflow term (Ω6). The wind term (Ω5) is the second largest, followed by the tide (Ω3), river discharge (Ω1) and coastal current terms. In both models the solar heat flux term (Ω4) makes the smallest contribution to ϕ. The available one-month comparison of model results to observations renders statistically insignificant correlation coefficients for both models. We speculate dynamical differences between conditions at the estuary mouth and the instrument location on the nearby shelf contribute to the model-observation mismatch. Other statistics, such as the root mean square error indicate that the unstratified model performs better than the two-layer model for the observation period. The latter model is, however, able to depict the importance of tides and winds in the computation of potential energy anomaly and is able to detect the response of ϕ due to strong wind events. While there is no clear model choice for the Delaware Bay, the unstratified model may be entirely inappropriate for highly stratified estuaries

Approximate Analytical Solutions to the Initial Data Problem of Black Hole Binary Systems

We present approximate analytical solutions to the Hamiltonian and momentum constraint equations, corresponding to systems composed of two black holes with arbitrary linear and angular momentum. The analytical nature of these initial data solutions makes them easier to implement in numerical evolutions than the traditional numerical approach of solving the elliptic equations derived from the Einstein constraints. Although in general the problem of setting up initial conditions for black hole binary simulations is complicated by the presence of singularities, we show that the methods presented in this work provide initial data with $l_1$ and $l_\infty$ norms of violation of the constraint equations falling below those of the truncation error (residual error due to discretization) present in finite difference codes for the range of grid resolutions currently used. Thus, these data sets are suitable for use in evolution codes. Detailed results are presented for the case of a head-on collision of two equal-mass M black holes with specific angular momentum 0.5M at an initial separation of 10M. A straightforward superposition method yields data adequate for resolutions of $h=M/4$, and an "attenuated" superposition yields data usable to resolutions at least as fine as $h=M/8$. In addition, the attenuated approximate data may be more tractable in a full (computational) exact solution to the initial value problem.Comment: 6 pages, 5 postscript figures. Minor changes and some points clarified. Accepted for publication in Phys. Rev.

Phytochrome A Antagonizes PHYTOCHROME INTERACTING FACTOR 1 to Prevent Over-Activation of Photomorphogenesis

Phytochrome A (phyA) is crucial to initiate the early steps of the transition between skoto- and photomorphogenesis upon light exposure and to complete this process under far-red light (typical of dense vegetation canopies). However, under prolonged red or white light, phyA mutants are hyper-photomorphogenic in many respects. To investigate this issue, we analyzed the late response of the transcriptome of the phyA mutant to red light. Compared to the wildtype(WT), hyper-responsive genes outnumbered the genes showing reduced response to red light in phyA. A network analysis revealed the co-expression of PHYTOCHROME INTERACTING FACTOR 1 (PIF1) with those genes showing hyperpromotion by red light in phyA. The enhanced responses of gene expression, cotyledon unfolding, hypocotyl growth, and greening observed in the phyA mutant compared to the WT were absent in the phyA pif1 double mutant compared to pif1, indicating that the hyper-photomorphogenic phenotype of phyA requires PIF1. PIF1 directly binds to gene promoters that displayed PIF1-mediated enhanced response to red light. Expression of mutant PIF1 deficient in interactions with phyA and phyB enhanced the long-term growth response to red light but reduced the expression of selected genes in response to red light. We propose that phytochrome-mediated degradation of PIF1 prevents over-activation of photomorphogenesis during early seedling development.Fil: Krzymuski, Martin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Cerdan, Pablo Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Zhu, Ling. University of Texas at Austin; Estados UnidosFil: Vinh, Amanda. University of Texas at Austin; Estados UnidosFil: Chory, Joanne. Salk Institute. Plant Biology Laboratory; Estados UnidosFil: Huq, Enamul. University of Texas at Austin; Estados UnidosFil: Casal, Jorge José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Grazing Collisions of Black Holes via the Excision of Singularities

We present the first simulations of non-headon (grazing) collisions of binary black holes in which the black hole singularities have been excised from the computational domain. Initially two equal mass black holes $m$ are separated a distance $\approx10m$ and with impact parameter $\approx2m$. Initial data are based on superposed, boosted (velocity $\approx0.5c$) solutions of single black holes in Kerr-Schild coordinates. Both rotating and non-rotating black holes are considered. The excised regions containing the singularities are specified by following the dynamics of apparent horizons. Evolutions of up to $t \approx 35m$ are obtained in which two initially separate apparent horizons are present for $t\approx3.8m$. At that time a single enveloping apparent horizon forms, indicating that the holes have merged. Apparent horizon area estimates suggest gravitational radiation of about 2.6% of the total mass. The evolutions end after a moderate amount of time because of instabilities.Comment: 2 References corrected, reference to figure update

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030