Tidal Phase Research Articles

Efficiency of energy and enstrophy transfers in periodical flows

We apply a coarse-graining technique to understand the efficiency of scale-to-scale transport of energy and enstrophy in a quasi-two-dimensional weakly turbulent periodic flow. The investigated periodic flow resembles the propagation of a monochromatic tide in a tidal channel, connected to open sea through an inlet. The interaction of the periodic flow with the inlet mouth generates vortical structures in a wide spectrum of scales, and recently, how the corresponding energy and enstrophy fluxes change their signs depending on the tidal phase has been shown. In the present study, we are interested to extend the analysis to the efficiency of the nonlinear transfer rates by analyzing the geometric alignment between the turbulent stresses and the strain rates for the energy, and the vorticity stress and large-scale vorticity gradient for the enstrophy. Our results suggest that, depending on the phase of the period, energy is efficiently transferred to larger scales (inverse cascade) in a finite range of scales, whereas the observed direct energy cascade for very small and very large scales is much less efficient. Enstrophy shows similar behaviors in terms of transitions between direct and inverse cascading; however, all transfers seem to be relatively inefficient.

Earthquakes and Heavy Rainfall Influence on Aquifer Properties: A New Coupled Earth and Barometric Tidal Response Model in a Confined Bi‐Layer Aquifer

AbstractAmong the impacts of earthquakes on aquifers, permeability change is one of the most challenging to quantify, since techniques to measure permeability evolution are scarce. The study of tidal response of boreholes is one of the most promising, yet complex to use in practice. We used 14 years of piezometric level measurements and two concurrent source signals, earth tidal strain and barometric pressure, for which we separated the respective contribution in a state‐of‐the‐art tidal analysis. We developed a new general analytical hydrogeological model, based on geological observations of a confined bi‐layer aquifer. It is able to match combined observations of earth and barometric tide phase lags which could not be explained by existing models. We demonstrate that its relative complexity can be overcome thanks to the results of tidal analysis, yielding a simpler model adapted to the Fond Lahaye site of the Martinique Island. The resulting evolution of diffusivity and loading efficiency, was validated independently with several pumping tests occurring all along the studied period. The transient diffusivity increases and decreases indicate which earthquakes impacted the aquifer, enabling to establish an empirical magnitude‐distance relationship criterion. This criterion confirms the suspected dependence on dynamic stresses, which decrease as the square of the hypocentral distance. Additionally, we investigate two other factors of diffusivity changes: heavy rainfall events and aquifer withdrawals, which demonstrates the sensitivity of volcanic aquifers properties to environmental and anthropogenic influence.

Study of Hydrodynamic Patterns of Tanjung Pasir Banten Waters to Support the NCICD Sea Wall Development Plan

Numerical modeling of hydrodynamics (HD) around the Tanjung Pasir Waters was carried out using MIKE 21 HD Flexible Mesh software to get the current velocity pattern conditions during the west and east monsoons. This activity is to support the NCICD sea wall construction plan. In addition, the results that will be obtained in this modeling are the conditions of the speed and direction of the current in various tidal conditions during spring and neap. The data used in this modeling include wind speed and direction, wave height, wave period, and wave direction. Based on the research that has been done, the validation value of Naotide tidal data on tidal field data is 93.8 %. HD MIKE 21 modeling results on field data have a validation value of 93.4 %. Extract points 4 and 5 which are the northernmost, have the highest current velocity values compared to the other points. In addition, when heading to the high tide phase, both spring and neap conditions, the current velocity value has the highest value.

Relationships between the tide and fatal drowning at surf beaches in New South Wales, Australia: Implications for coastal safety management and practice

Beaches are popular, recreational destinations, but can be hazardous environments where drowning fatalities and other types of injuries can occur. Ocean lifeguards and beach safety managers make operational safety decisions based on ocean conditions, including various elements of the tide. This study addresses assumptions about the tide that are common in beach safety management; assessing the scientific basis that informs these decisions by evaluating the relationship between elements of the tide and fatal drowning on microtidal surf beaches in New South Wales (NSW), Australia. Lower tidal water levels and time periods closer to low tide were associated with increased likelihood of fatal drowning at surf beaches, while tidal phase (rising vs falling), tide range, and the rate of change of falling or rising water levels were not. These results have implications for ocean safety management and those responsible for educating the public about beach safety issues. Broad statements or anecdotal opinions that are not location or beach-specific should avoid describing times with falling water levels (an outgoing tide) as being inherently more dangerous.

Sensitivity analysis of polar orbiter motion to lunar viscoelastic tidal deformation

We investigate the impact of viscoelastic tidal deformation of the Moon on the motion of a polar orbiter. The dissipative effects in the Moon’s interior, i.e., tidal phase lags, are modeled as Fourier series sampled at given frequencies associated with linear combinations of Delaunay arguments, the fundamental parameters describing the lunar motion around the Earth and the Sun. We implement the tidal model to evaluate the temporal lunar gravity field and the induced perturbation on the orbiter. We validate the numerical scheme via a frequency analysis of the perturbed orbital motion. We show that, in the case of the Lunar Reconnaissance Orbiter at a low altitude of less than 200 km, the main lunar tides and hence the potential Love numbers around the monthly and some multiple frequencies are dynamically separable. The omission of those effects in practice introduces a position error at the level of a few decimeters within 10 days.

Cross‐shore suspended sediment transport in a macro‐tidal and low‐sloping upper shoreface

AbstractThe driving mechanisms of sediment transport across the upper shoreface have been poorly examined to date because of the scarcity of field measurements beyond the intertidal area, which is mainly due to instrumentation difficulties. Here, we investigate the cross‐shore suspended sediment transport from synchronized time series of bottom pressure, current velocity and suspended sediment concentration measured by 13 m water depth, in a macro‐tidal and low‐sloping shoreface, under storm waves and fair weather conditions. Depending on the tidal phase and the incoming wave height, the measuring structure was alternatively located in the shoaling zone and in the outer surf zone. The analysis of field observations first revealed that steady currents dominate suspended transport, with a notable contribution of the wave‐driven return current under storm wave conditions. Cross‐spectral analysis further indicates that short waves globally induce an offshore‐directed transport under energetic conditions associated with a crest‐to‐trough phase lag effect. The contribution of infragravity (IG) waves, which reaches as much as 20% of the total transport, shows contrasting directions depending on whether IG waves are bound to the short wave groups or propagate as free waves.

Influence of Wave–Current Interaction on a Cyclone-Induced Storm Surge Event in the Ganges–Brahmaputra–Meghna Delta: Part 1—Effects on Water Level

The Ganges–Brahmaputra–Meghna Delta (GBMD) located in the head of the Bay of Bengal is regularly affected by severe tropical cyclones frequently. The GBMD covers the Bangladesh coast, which is one of the most vulnerable areas in the world due to cyclone-induced storm surges. More than 30% of the total country’s population lives on the Bangladesh coast. Hence, it is crucial to understand the underlying processes that modulate the storm surge height in the GBMD. A barotropic numerical 3D model setup is established by using Delft3D and SWAN to investigate a cyclone-induced storm surge event. The model is calibrated and validated for Cyclone Sidr in 2007 and applied to six idealized cyclonic scenarios. Numerical experiments with different coupling configurations are performed to distinguish the contribution of wind, tides, waves, and wave–current interactions (WCI) on the storm surge height. Results show that the wind-driven setup is the dominant contributor to the storm surge height during cyclonic events. Based on the tidal phase and wind direction, the interaction between tide and wind can increase or decrease the magnitude of the storm surge height. Finally, considering the wind-driven wave may increase the surge height up to 0.3 m along the coastline through a strong wave setup.

Surface Convergence Zones due to Lagrangian Residual Flow in Tidally Driven Estuaries

Abstract Buoyant material, such as floating debris, marine organisms, and spilled oil, is aggregated and trapped within estuaries. Traditionally, the aggregation of buoyant material is assumed to be a consequence of converging Eulerian surface currents, often associated with lateral (cross-estuary) density gradients that drive baroclinic lateral circulations. This study explores an alternative aggregation mechanism due to tidally driven Lagrangian residual circulations without Eulerian convergence zones and without lateral density variation. In a tidally driven estuary, the depth-dependent tidal phase of the lateral velocity varies across the estuary. This study demonstrates that the lateral movement of surface trapped material follows the tidal phase, resulting in a lateral Lagrangian residual circulation known as Stokes drift for small-amplitude motions. For steeper bathymetry, the lateral change in tidal phase is greater and the corresponding lateral Lagrangian residual flow faster. At local depth extrema, e.g., in the thalweg, depth does not vary laterally, so that the associated tidal phase is laterally constant. Therefore, the Stokes drift is weak near depth extrema resulting in Lagrangian convergence zones where buoyant material concentrates. These ideas are evaluated employing an idealized analytic model in which the along-estuary tidal flow is driven by an imposed barotropic pressure gradient, whereas cross-estuary flow is induced by the Coriolis force. Model results highlight that convergence zones due to Lagrangian residual velocities are efficient in forming persistent aggregation regions of buoyant material along the estuary. Significance Statement Our study focuses on the aggregation of buoyant material (e.g., debris, oil, organisms) in estuaries. Traditionally, the aggregation of buoyant material is assumed to be a consequence of converging Eulerian surface currents, often associated with lateral (cross-estuary) density gradients that drive baroclinic lateral circulations. Our study explores an alternative aggregation mechanism due to tidally driven Lagrangian residual circulations without Eulerian convergence zones and without lateral density variation. Our results highlight that convergence zones due to Lagrangian residual velocities are efficient in forming persistent aggregation regions of buoyant material along the estuary.

Observation of Scintillation Enhancements and Large‐Scale Structures Within the Equatorial Ionization Anomaly During a Sudden Stratospheric Warming Event

AbstractTotal electron content (TEC) and L‐band scintillations measured by several networks of GPS and GNSS receivers that operate in South and Central America and the Caribbean region are used to observe the morphology of the equatorial ionization anomaly (EIA), examine the evolution of plasma bubbles, and investigate the enhancement of L‐band scintillations that occurred on February 12 and 13, 2016. A few weak and short magnetic storms developed these days, and a minor sudden stratospheric warming (SSW) event was initiated a few days before. During these unusual conditions, TEC maps reported a split of the otherwise continuous crests of the EIA and the formation of a large‐scale (thousands of kilometers) almost‐circular structure. The western part of the southern crest faded, and a north‐south aligned segment developed near the center of the South American continent, joining the north and south crests of the EIA, forming an anomaly that resembled a closed loop on the eastern side of the continent. Concurrently with the anomaly events, several GPS stations reported increases in the L‐band scintillation index from 0.4 to values greater than 1. We analyzed TEC values from receivers between ±6° from the magnetic equator to identify and follow TEC depletions associated with plasma bubbles when they reach different stations. Although the magnetic activity was moderate (Kp = 3°), we believe that the anomaly redistribution and the scintillation enhancements are not related to a prompt penetration electric field but to enhancing the semidiurnal lunar tide propitiated by the onset of the minor SSW event. We found that depending on the lunar tide phase cycle, the neutral wind's meridional component can augment sub‐km scale irregularities and enhance L‐band scintillations through the wind gradient instability when U·n < 0 or the action of wind gradients (U) within the bubbles. Our observations imply that the SSW event enables prominent changes in the thermosphere wind system at F‐region altitudes.

Understanding tidal mixing at the Strait of Gibraltar: A high-resolution model approach

The Strait of Gibraltar is a narrow and shallow channel that controls the Mediterranean Sea thermohaline and biogeochemical balances. Strong tidal currents significantly modulate exchanges across this strait and induce an intense vertical mixing, impacting both the Mediterranean Sea and the Atlantic Ocean on a climatic scale. However, the turbulent processes controlling the tidal mixing location, timing, and magnitude remain unclear. To fill this gap, we investigate tidal mixing at the Strait of Gibraltar in yearly twin tidal and non-tidal simulations from a regional configuration of the three-dimensional numerical model MITgcm, using a high spatial resolution around the Strait of Gibraltar (1/200°, 100 vertical levels). More specifically, we investigate the model turbulence closure scheme, based on a turbulent kinetic energy budget, and illustrate that vertical buoyancy fluxes should be preferred to diapycnal diffusivities as mixing indicators. In agreement with previous literature, we find that tides strongly intensify vertical mixing and motions within the Strait of Gibraltar. We then demonstrate that tidal mixing relies on two main ingredients: a sustained vertical shear of horizontal velocities and a local weakening of stratification. In the Mediterranean layer, the former drives diapycnal mixing near the seafloor and the latter in shallower areas above the prominent sills of the strait. We also evidence the frequent but irregular occurrences of static instabilities in the vicinity of these sills. In the Atlantic layer, both vertical shear and stratification are involved in diapycnal mixing that develops along the trail of the eastward internal bore released at the Camarinal sill. At high frequency, the local weakening of stratification results from convergence and divergence patterns in the vicinity of the Camarinal and Espartel sills, feeding recirculation cells between the Atlantic and Mediterranean layers. In addition, we highlight that diapycnal mixing mainly develops during the westward tidal phase in the Mediterranean layer and the eastward tidal phase in the Atlantic layer. We conclude by proposing a revised conceptual view of tidal mixing at the Strait of Gibraltar, where tidally-induced recirculation cells play an instrumental role in transforming the exchanged water masses. Overall, this study emphasizes the relevance of a realistic representation of both tides and abrupt topography to simulate the exchanges through the Strait of Gibraltar and argues for the use of a specific tidal mixing parameterization otherwise.

Mass transport pattern and mechanism in the tide-dominant Bohai Sea

Based on a numerical hydrodynamic model and Lagrangian particle tracking method, the Lagrangian flow network and the Lagrangian residual velocity were derived to exhibit the mass transport pattern in the tide-dominant Bohai Sea. The characteristics of the Lagrangian flow network, represented by degree and hydrodynamic provinces, show distinct regional features in the Central Basin and the three bays. The first-order Lagrangian residual velocity (i.e., the mass transport velocity) can be well maintained over a dozen averaging tidal periods, with its magnitude slightly decreasing with the increasing number of tidal periods. The second-order Lagrangian residual velocity (i.e., the Lagrangian drift velocity) includes the dependence on the initial tidal phase, which is also weakened with the increasing number of tidal periods. The mechanism behind the above two features of the Lagrangian residual velocity is explained theoretically. In the Bohai Sea, with about 15 averaging tidal periods, the Lagrangian residual velocity is approximately independent of the initial tidal phase and close to the mass transport velocity. The streamlines of the Lagrangian residual velocity averaged over 15 tidal periods are parallel to the province boundaries in the Lagrangian flow network, which means that the Lagrangian flow network is determined by the Lagrangian residual current. This may lay the foundation for using Lagrangian flow network to analyze and quantify flow and transport pathways in shallow, tide-dominated coastal regions.

Comprehensive studies of river mouths flowing into the Onezhskiy Bay of the White Sea

Comprehensive oceanological studies depending on the tidal phase are important for an objective assessment of the patterns of biogeochemical parameters in the White Sea. Rivers are the main contributors of pollutants from the watershed to the White Sea. The studies of the mouths flowing into the Onezhskiy Bay of the White Sea were carried out from June 20 to June 28, 2023. The distributions of hydrophysical, hydrochemical and biological parameters were obtained depending on the phase of the tidal cycle. The maximum of total phosphorus content was observed in the Nizhny Vyg River Mouth – 42 μg/l, the highest concentration of total nitrogen was in the Onega River Mouth – 0.37 mg N/l. In the mouth of the Kem’ River, concentration of ammonium nitrogen prevailed among inorganic forms, like directly in the river, which indicates anthropogenic impact. The highest values of chlorophyll-a were observed at the most desalinated station, in the Onega River the highest were detected – 2.20 mg/m3. The influence of the phases of the tidal cycle in the study area on the spatial and temporal variability of environmental characteristics was manifested in changes in temperature and salinity.

The Gondola: a boat to respond to the history, and the morpho-dynamics of the Venice Lagoon

Origin and evolution of the gondola have been reconstructed from historical and documentary written and pictorial sources (figures in books, engravings and paintings), in relation to the physical environment of the Lagoon, its morpho-dynamics with shallow and deep waters, marshes and canals. Particular care has been applied to the physical and hydrodynamic aspects in order to interpret the data and understand how the ancient Venetians could have had an advanced knowledge of the tidal range from sea stairs, tidal phase from the algae colour and direction, bottom depth from surface ripples, and exchanges between the Lagoon and the sea from suspended debris. The various elements of the boat are considered in terms of use and physical advantage, e.g. rowing style, cabin, hull and decorations. The boat evolution has been followed and documented over the centuries. This study clarifies the original shape of the gondola in the 11th century, from the analysis of the contemporary manuscripts and Byzantine mosaics in Ravenna and Venice, and a tablet of the early 14th century. In the 16th century, the gondola changed shape and size. The reason of this restyling was unknown, but has been found in the contemporary edicts, diaries and chronicles and other historical sources. The transformation was kept as a military secret, as well the production of a fleet of small boats provided of rostrums to sail on the rivers Po and Adige and fight against Ferrara and its Allies of the League of Cambrai. A comparison with the Viking- Norman vessels of Bayeux, Palermo and some codices show several strong analogies with the military gondolas of the 16th century. An overview of the written and pictorial sources has allowed to classify the various gondola types and recognize several technical details. Finally, the size and depth have been considered to interpret the ancient chronicles that mentioned that in the occasion of the most extreme storm surges, the gondolas could ride on San Marco Square, i.e. the flooding water depth necessary to float and to navigate over street paving.

ПРОДОЛЖИТЕЛЬНЫЕ ПОВЫШЕНИЯ И ПОНИЖЕНИЯ УРОВНЯ ПОКРЫТОГО ЛЬДОМ МОРЯ У ПОБЕРЕЖЬЯ ОХОТСКОГО МОРЯ В ЗАЛИВЕ МОРДВИНОВА

The analysis of the causes of sea level rise and fall under the ice was carried out using sea level time series obtained by measurements performed in the coastal zone of the southeastern coast of Sakhalin island in 2019–2021. The analysis of all the events of sea level rising and falling showed that they are not associated with tidal waves, the minima of sea level correspond to different phases of tide and the duration of the events is several times longer than the period of the daily tidal wave. Analysis of the causes of six detected events of sea level fall showed that they are the result of long-lasting winds of the western direction. The fast ice field breaks away from the shore due to these winds and at the place of formed polynya a small set-down appears under the influence of the same winds. Instruments recorded this sea set-down as a decrease of sea level. The analysis of the seven selected events associated with sea level rise showed their connection with a decrease of atmospheric pressure during the cyclones passage near the observation area. The comparison of sea level behaviour and regression coefficients for an ice-covered sea with similar ones for an ice-free sea showed that for an ice-free sea, the level rises are about twice longer in time and occur later than the atmospheric pressure minima. At the same time, the absolute values of the regression coefficient for an ice-free sea are on average almost four times less than for an ice-covered one. The assumption that atmospheric pressure fluctuations can saturate the continental shelf waves has been verified using the Buchwald and Adams shelf wave model. Shelf wave periods of 37.7 hours calculated from spectra confirmed the possibility of transmission to sea level rise, and the shelf waves themselves can be saturated by atmospheric pressure fluctuations from passing cyclones.

Vulnerability of biological resources to potential oil spills in the Lower Amazon River, Amapá, Brazil.

Ships that transport oil or derivatives on the Lower Amazon River waterway are at a considerably high risk of suffering spills, with severe environmental and socioeconomic consequences. The present study is aimed at modeling and simulating the oil dispersion and magnitude of these accidents in terms of the vulnerability of biological resources, considering two oil types most often transported by medium-sized tankers in the region (S500 and S10). The study method was as follows: (a) secondary data were collected from local species, and the coastal sensitivity index (CSI) was calculated, obtained from Brazil's Letters of Environmental Sensitivity to Oil Spill (Cartas de Sensibilidade Ambiental ao Derramamento de Óleo (SAO)); (b) ship traffic information was obtained from Brazil's Statistical Yearbook of Waterway (Anuário Estatístico Aquaviário (ANTAQ)); (c) modeling and numerical simulation of oil spills in water were performed, in order to investigate dispersion scenarios (SisBaHia); (d) three numerical scenarios of oil plume dispersion (in May and November) were integrated to assess species vulnerability in three zones of environmental interest (I, II, and III). Some species identified in zone II were considered to be the most vulnerable (fish, plankton, aquatic mammals, amphibians, aquatic invertebrates, trees, and plants), with the mammal Sotalia fluviatilis being at risk of extinction (Gervais & Deville, 1853). The simulated scenarios showed that contingency plans should have a minimum response time of 3h and a maximum response time of 72h to prevent the oil plumes from dispersing as far as 170km longitudinally, depending on the zone, season, and tidal phase. Thus, a total of 62 sites of biological resources were identified in the literature recorded from 2016. Considering them, 324 species of flora and fauna were recorded, distributed in the following seven groups: (i) 49 tree and plant species, (ii) 37 amphibian species, (iii) 2 aquatic invertebrate species, (iv) 23 invertebrate species, (v) 1 aquatic mammal species, (vi) 95 fish species, and (vii) 117 planktonic species. A failure to respond to these accidents would impact immense intact aquatic areas and ecosystems, with unpredictable consequences for local biodiversity conservation.

Beyond the linear tide: impact of the non-linear tidal response of neutron stars on gravitational waveforms from binary inspirals

ABSTRACT Tidal interactions in coalescing binary neutron stars modify the dynamics of the inspiral and hence imprint a signature on their gravitational wave (GW) signals in the form of an extra phase shift. We need accurate models for the tidal phase shift in order to constrain the supranuclear equation of state from observations. In previous studies, GW waveform models were typically constructed by treating the tide as a linear response to a perturbing tidal field. In this work, we incorporate non-linear corrections due to hydrodynamic three- and four-mode interactions and show how they can improve the accuracy and explanatory power of waveform models. We set up and numerically solve the coupled differential equations for the orbit and the modes and analytically derive solutions of the system’s equilibrium configuration. Our analytical solutions agree well with the numerical ones up to the merger and involve only algebraic relations, allowing for fast phase shift and waveform evaluations for different equations of state over a large parameter space. We find that, at Newtonian order, non-linear fluid effects can enhance the tidal phase shift by $\gtrsim 1\, {\rm radian}$ at a GW frequency of 1000 Hz, corresponding to a $10{{\%}}-20{{\%}}$ correction to the linear theory. The scale of the additional phase shift near the merger is consistent with the difference between numerical relativity and theoretical predictions that account only for the linear tide. Non-linear fluid effects are thus important when interpreting the results of numerical relativity and in the construction of waveform models for current and future GW detectors.

Tidal effects on periodical variations in the occurrence of singing humpback whales in coastal waters of Chichijima Island, Ogasawara, Japan

Marine organisms inhabiting coastal waters are known to be driven by periodic cycles such as diel, tidal, and seasonal changes. Humpback whales (Megaptera novaeangliae) breed in shallow and warm coastal waters, with males singing complex songs during the breeding season. To investigate periodic variations in humpback whale singing activities, we conducted fixed passive acoustic monitoring in the Ogasawara (Bonin) Islands, Japan, from winter to spring during 2016–2018. The singing activity and individual number of singers were observed throughout the day and night using a very long baseline passive acoustic array. The occurrence of singers peaked before sunrise and in the evening and was reduced during the daytime. The frequency of song reception depended on the tidal phase. A generalised additive model demonstrated that the occurrence of singers increased during the flood tide and decreased during the ebb tide in the waters west of Chichijima Island. These results suggest that the singing behaviour of humpback whales in breeding areas is affected by the diel and tidal cycles. Male humpback whales may change their behaviour or singing location depending on the strength and direction of the tidal current, considering that the selection of a stable location is beneficial for singing whales.

Efficacy and Safety of Single-Agent Zandelisib Administered By Intermittent Dosing in Patients with Relapsed or Refractory (R/R) Follicular Lymphoma (FL): Final Results of the Tidal Phase 2 Study

Introduction: Zandelisib is a novel, highly selective, structurally differentiated, oral PI3Kδ inhibitor. Its on-target residence time (≥5 hours) and high volume of distribution lead to higher tumor exposure relative to plasma over time. In a dose optimization Phase 1b study in various B-cell malignancies, zandelisib was evaluated initially by continuous dosing (CD), and then by intermittent dosing (ID) to allow regulatory T-cell repopulation, thereby reducing immune-related adverse events (AEs) (Pagel et al. Lancet Oncol 2022). The TIDAL trial (NCT03768505) started as a randomized, double-blind, 2-arm study to evaluate the safety and efficacy of zandelisib CD (n=16) vs. ID (n=121) in R/R FL and marginal zone lymphoma (MZL) patients (pts). Here we present results from the final analysis of the FL cohort in the ID arm. Methods: Eligible pts ≥18 years with FL Grade I-IIIA, ECOG performance status 0-1, progressive disease after ≥2 prior therapies including an anti-CD20 antibody and chemotherapy, and no prior PI3K inhibitor, provided consent and subsequently received zandelisib 60 mg orally once daily for two 28-day cycles, then ID (days 1-7 of 28-day cycles). The study arm evaluating zandelisib 60 mg daily CD closed early to enrollment after maturing data from the Ph 1b study showed pts on ID having fewer discontinuations due to treatment-emergent AEs and a high rate of durable responses. Study treatment was administered until disease progression or intolerance. The primary efficacy endpoint was objective response rate (ORR) as assessed by blinded independent central review (BICR) using modified Lugano Classification. Secondary endpoints were duration of response (DOR), complete response (CR) rate, median progression-free survival (mPFS), safety and tolerability. Prophylaxis for Pneumocystis jirovecii pneumonia was not mandatory in this single agent trial. Results: Between June 2019 and September 2021, 121 FL pts were enrolled in the ID arm, intent-to-treat (ITT) population, with the initial 91 pts representing the primary efficacy population (PEP). The median number of prior therapies was 3 (range 2-8), 28 pts (23.1%) had prior stem cell transplant, 54 pts (44.6%) were refractory to last therapy, 42 pts (34.7%) had bulky disease (≥5 cm), and 68 pts (56.2%) were POD24. Efficacy data overall and by subgroup (POD24, prior therapy, refractoriness) are shown in the Table. The ORR (CR rate) in the PEP and ITT were 72.5% (36.3%) and 70.2% (34.7%). With median follow-up of 11.3 months in PEP and 9.3 months in ITT, median DOR was estimated at 16.4 and 16.4 months, respectively. Preliminary PFS in the ITT population is shown in the Figure. With a median follow-up of 14.3 months (range: 1.0-30.5) among 121 pts, the most common AEs (all grade/Gr ≥3) were diarrhea (37.2%/5.8%), neutropenia (28.9%/21.5%), nausea (22.3%/0), fatigue (19.0%/0), pyrexia (19.0%/1.7%), and abdominal pain (15.7%/0.8%). 15 pts (12.4%) discontinued therapy due to treatment-related AE. Gr ≥3 AEs of special interest (AESI) in the ID arm were diarrhea in 7 pts (5.8%), lung infection/pneumonia in 6 (5.0%), noninfectious colitis in 4 (3.3%), rash in 4 (3.3 %), stomatitis in 3 (2.5%), and 1 (0.8%) each for ALT and AST increased and noninfectious pneumonitis. In 16 pts in the CD arm, 5 (31.3%) discontinued therapy due to drug-related AE, and 4 (25%) had Gr ≥3 diarrhea/colitis. Gr 5 AEs in the ID arm, excluding COVID-19, were tumor lysis syndrome (1 pt) and pneumonia (1 pt). There were 17 pts with COVID events, fatal in 5. Conclusions: Single agent zandelisib on ID was associated with high rate of durable responses (72.5% ORR, 36.3% CR rate in PEP) in heavily pretreated R/R FL pts, including those with POD24 and refractory disease, and was associated with a relatively lower incidence of Gr ≥3 AESI and AE-related discontinuations, compared with CD. Based on the safety and efficacy profiles observed in this study, these results support further evaluation of zandelisib ID, alone or in combinations, in various B-cell malignancies. Zandelisib plus rituximab vs. chemoimmunotherapy is being evaluated in the randomized phase 3 study COASTAL in R/R FL and MZL (NCT04745832). Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Modeling the hydrodynamics of a tidal inlet during bay-side storms

Bay-side storms, defined here as storms with tracks on the landward side of barrier islands, may disturb the hydrodynamics of inner bays to a larger extent than on the ocean side. These storms are common in large-scale O(>100,000 m) estuarine systems and have the potential to modify the circulation in bays and within tidal inlets. Here, we provide an overview of the hydrodynamic response of a tidal inlet under forcings caused by bay-side storms and explore the role of waves in modulating the release of storm surge from the back-barrier regions into the ocean. A two-dimensional horizontal numerical model including wave-current interactions is calibrated and validated against field observations of water levels and depth-averaged velocities at Oregon Inlet, NC. The model is then used to investigate the effect of synthetic bay-side storms with varying wave conditions and water levels based on those generated by Hurricane Irene (2011), which is the strongest bay-side storm to hit the Outer Banks of North Carolina in the last two decades. Effect of timing of the peak storm surge during the ebb and flood phases of the tide is also explored.Results from synthetic storms indicate that, during bay-side storms, the water level gradient along the inlet favors ebbing flows regardless of the timing of the storms relative to tidal phase. These results suggest that waves might be responsible for any influx of volume to the bay during high bay-side surge events. Wave blocking effects were found to be stronger along the ebb shoal and only reached the flood delta when bay water levels were nearly the same as the ocean water levels. Reduction of currents by waves in the inlet have the potential to extend the duration of the inundation period in the back barrier region. Bay-side storms also caused flux enhancement over inlet shoals and channels in the flood delta, which could have implications for circulation patterns as well as the morphodynamics of the system.

Follow-up analyses of the binary-neutron-star signals GW170817 and GW190425 by using post-Newtonian waveform models

We reanalyze the binary-neutron-star signals, GW170817 and GW190425, focusing on the inspiral regime to avoid uncertainties on waveform modeling in the postinspiral regime. We use post-Newtonian waveform models as templates, which are theoretically rigid and efficiently describe the inspiral regime. We study potential systematic difference in estimates of the binary tidal deformability $\tilde{\Lambda}$ by using different descriptions for the point-particle dynamics and tidal effects. We find that the estimates of $\tilde{\Lambda}$ show no significant systematic difference among three models for the point-particle parts: TF2, TF2g, and TF2+, when they employ the same tidal model. We compare different tidal descriptions given by different post-Newtonian orders in the tidal phase. Our results indicate that the estimates of $\tilde{\Lambda}$ slightly depend on the post-Newtonian order in the tidal phase and an increase in the tidal post-Newtonian order does not lead to a monotonic change in the estimate of $\tilde{\Lambda}$. We also compare the estimate of $\tilde{\Lambda}$ obtained by the post-Newtonian tidal model and numerical-relativity calibrated tidal models. We find that the post-Newtonian model gives slightly larger estimate of $\tilde{\Lambda}$ and wider posterior distribution than the numerical-relativity calibrated models. According to Bayesian model comparison, it is difficult to identify a preference among the post-Newtonian orders by relying on the GW170817 and GW190425 data. Our results indicate no preference among numerical-relativity calibrated tidal models over the post-Newtonian model. Additionally, we present constraints on equation-of-state models for neutron stars with the post-Newtonian model, which show that the GW170817 data disfavor less compact models, though they are slightly weaker constraints than the numerical-relativity calibrated tidal models.