The Virginia Chesapeake Bay: recent sedimentation and paleodrainage

A comparison of the bathymetric surveys of the 1850-series and 1950-series indicated an average sedimentation rate for the Virginia Chesapeake Bay of 0.55 m (1.81 ft) for the last century. A statistically significant relationship between the depth of water and the rate of sedimentation was found where high rates of sedimentation exist in extremely shallow water (0 to 2 m) and in intermediate depths (6 to 13 m), while low rates exist between 2 m and 6 m, and in some cases in water deeper than 13 m. The results of 900 km of continuous seismic reflection profiles taken in the Virginia and lower-Maryland Chesapeake Bay indicate that the ancestral Rappahannock, Piankatank, York, and James rivers were not tributary to the ancestral Susquehanna River during the Wisconsin Glaciation as was previously believed. The ancestral Rappahannock, Piankatank, and York rivers converge and flow out of the present bay area through a paleochannel located under Tail of the Horseshoe Shoal on the south side of the Bay entrance. These combined rivers probably converged with the ancestral James River somewhere on the present continental shelf. A paleochannel in the Mainstem of the Bay north of the Potomac River mouth has an apparent thalweg depth of -42 m (-138 ft), whereas a much deeper channel at -61 m (-200 ft) has been reported by Ryan (1953) in the upper bay reaches. This suggests that the Susquehanna did not flow in the Mainstem region during the Wisconsinan Glaciation and most probably flowed in the Tangier Sound region. No evidence was found to support theories concerning the existence of significant Post-Tertiary crustal movement in the lower Bay region

Storm Surge Wave Interaction Model: Literature review of surge models, model description, and results of Virginian Sea Model

ABSTRACT The effect of storm surge on wave refraction patterns along 320 km of shoreline in the Virginian Sea (Mid-Atlantic Shelf) has been investigated using an analytical model. Two types of storm surge patterns based on Bodine (1971) and Jelesnianski (1972 and 1974) are used to alter the ocean surface of the Virginian Sea Wave Climate Model (Goldsmith, et al., 1974). The first pattern, based on Bodine\u27s (1971) Bathystrophic Storm Surge Model, is of circular shape (with the maximum sea level rise in the center) and in real situations results mostly from the inverted barometric pressure effect associated with intense low-pressure storm systems, wind setup and the astronomic tide. The center of these surge was located at two places in 30 m water depths on the shelf in order to determine if a general wave response pattern could be established, and to delineate a sequence of wave responses. The second type of surge model, based on the general pattern shown by Jelesnianski (1972 and 1974), develops as the storm moves towards shore, and the effects of shoaling, wind stress, and inertia change the shape and height of the surge. At landfall the surge is a long, narrow strip impinging against the shore with a seawardly exponential decay, and with a higher surge height to the right of center. Based on a comparison of two sets of wave ray diagrams, and shoreline wave energy and wave height distributions computed for (a) the two surge types and (b) no-surge conditions, using similar initial wave input parameters, the characteristics of the general wave response models are briefly sununarized for both surge types as follows: Shelf Surge: Changing wave refraction patterns result in: (a) maximum increases in shoreline wave energy located to the north and south of that point of land downwave of the storm; and (b) decreases in shoreline wave energy in a shadow zone directly downwave from the storm surge. Shoreline Surge: An increase in longshore drift caused by lesser wave refraction. The deeper water close to shore results in a greater shoreline breaker angle than that observed during no-surge conditions. Thus irrespective of the wave height, any type of surge will cause significant changes in the shoreline wave refraction patterns resulting in local increases in longshore drift. The tendency for increases in longshore transport, and concomitant decreases in offshore-onshore transport, is thus promoted by water surges, irrespective of wave size and direction and results in permanent local losses of sediment

A 100-Year Sediment Budget for Chesapeake Bay

Chesapeake Bay is a depositional basin that is filling from both ends and the sides. During the century ended in the mid-1950s between 1.0 x 109 and 2.92 x 109 metric tons of sediment accumulated in the bay. The bay\u27s largest tributary, the Susquehanna River, is a major source of fine-grained sediments; its coarser load being trapped by dams. The continental shelf is the largest single source of sediment for the basin. A massive quantity of sand, perhaps as much of forty percent of the net deposition, enters the bay between the Virginia capes and works its way tens of kilometers upstream, potentially as far north as Tangier Island, near the Virginia-Maryland boundary. Other sources of sediment are shoreline erosion, biogenic production, preHolocene outcrops, and the other tributaries. These tributary estuaries do provide coarse sediment to the bay through longshore transport and bedload movement in the nearshore.shallows and, perhaps, in the channel bottom. The contribution of suspended or fine-grained sediment by the tributary estuaries is unknown. Indeed they may be sinks and not sources. \u27The contribution of the tributary estuaries and the quantification of the bay-mouth sand-source and uncertainties associated with the bathymetric comparisons in the determination of the net mass of sediment deposition, make it difficult to balance a sediment budget for Chesapeake Bay. Most of the imbalance is in the sand fraction within the Virginia portion of the system; with far more sand being deposited than can be accounted for by the independently quantifiable sources. Not considering the continental shelf as a source of sand, the budget fails to balance by a factor of between 2.7 and 7.6. Making certain assumptions about the quantity of sanQ entering the bay through its mouth (the continental shelf source), the difference can be sufficiently reduced that the budget more nearly balances

Response of the South China Sea to tropical cyclone Ernie 1996

Journal of Geophysical Research, American Geophysical Union, 105, 13991-14009.A moving tropical cyclone is an intense localized source of surface wind stress and wind stress curl that produces a significant response in the ocean environment, especially in the ocean thermal structure, the upper ocean currents, and the sea surface elevation. Such a response has been well identified in the open-ocean region, but not in the coastal ocean region. In this study we use the Princeton Ocean Model with 20 km horizontal resolution and 23 sigma levels conforming to a realistic bottom topography to identify the response of the South China Sea to Tropical Cyclone Ernie 1996. Results show strong similarities in the responses between open ocean and coastal regions, including near-surface strong a symmetric response such as divergent currents with near-inertial oscillations, significant sea surface temperature cooling, biase to the right of the storm track, sea surface depressions in the wake of the storm, and subsurface intense upwelling and cooling at the base of the mixed layer to the right of the storm track. The unique features of the SCS response to Ernie are also discussed

Summary of findings and research recommendations from the Gulf of Mexico Research Initiative

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wilson, C. A., Feldman, M. G., Carron, M. J., Dannreuther, N. M., Farrington, J. W., Halanych, K. M., Petitt, J. L., Rullkotter, J., Sandifer, P. A., Shaw, J. K., Shepherd, J. G., Westerholm, D. G., Yanoff, C. J., & Zimmermann, L. A. Summary of findings and research recommendations from the Gulf of Mexico Research Initiative. Oceanography, 34(1), (2021): 228–239, https://doi.org/10.5670/oceanog.2021.128.Following the Deepwater Horizon explosion and oil spill in 2010, the Gulf of Mexico Research Initiative (GoMRI) was established to improve society’s ability to understand, respond to, and mitigate the impacts of petroleum pollution and related stressors of the marine and coastal ecosystems. This article provides a high-level overview of the major outcomes of the scientific work undertaken by GoMRI. This i scientifically independent initiative, consisting of over 4,500 experts in academia, government, and industry, contributed to significant knowledge advances across the physical, chemical, geological, and biological oceanographic research fields, as well as in related technology, socioeconomics, human health, and oil spill response measures. For each of these fields, this paper outlines key advances and discoveries made by GoMRI-funded scientists (along with a few surprises), synthesizing their efforts in order to highlight lessons learned, future research needs, remaining gaps, and suggestions for the next generation of scientists

Clinical Characteristics Associated with Bacterial Bloodstream Coinfection in COVID-19

INTRODUCTION: Inappropriate antibiotic use in COVID-19 is often due to treatment of presumed bacterial coinfection. Predictive factors to distinguish COVID-19 from COVID-19 with bacterial coinfection or bloodstream infection are limited. METHODS: We conducted a retrospective cohort study of 595 COVID-19 patients admitted between March 8, 2020, and April 4, 2020, to describe factors associated with a bacterial bloodstream coinfection (BSI). The primary outcome was any characteristic associated with BSI in COVID-19, with secondary outcomes including 30-day mortality and days of antibiotic therapy (DOT) by antibiotic consumption (DOT/1000 patient-days). Variables of interest were compared between true BSI (n = 25) and all other COVID-19 cases (n = 570). A secondary comparison was performed between positive blood cultures with true BSI (n = 25) and contaminants (n = 33) on antibiotic use. RESULTS: Fever (\u3e 38 °C) (as a COVID-19 symptom) was not different between true BSI (n = 25) and all other COVID-19 patients (n = 570) (p = 0.93), although it was different as a reason for emergency department (ED) admission (p = 0.01). Neurological symptoms (ED reason or COVID-19 symptom) were significantly higher in the true BSI group (p \u3c 0.01, p \u3c 0.01) and were independently associated with true BSI (ED reason: OR = 3.27, p \u3c 0.01; COVID-19 symptom: OR = 2.69, p = 0.03) on multivariate logistic regression. High (15-19.9 × 10(9)/L) white blood cell (WBC) count at admission was also higher in the true BSI group (p \u3c 0.01) and was independently associated with true BSI (OR = 2.56, p = 0.06) though was not statistically significant. Thirty-day mortality was higher among true BSI (p \u3c 0.01). Antibiotic consumption (DOT/1000 patient-days) between true BSI and contaminants was not different (p = 0.34). True bloodstream coinfection was 4.2% (25/595) over the 28-day period. CONCLUSION: True BSI in COVID-19 was associated with neurological symptoms and nonsignificant higher WBC, and led to overall higher 30-day mortality and worse patient outcomes

Activation of Wnt Signaling by Chemically Induced Dimerization of LRP5 Disrupts Cellular Homeostasis

Wnt signaling is crucial for a variety of biological processes, including body axis formation, planar polarity, stem cell maintenance and cellular differentiation. Therefore, targeted manipulation of Wnt signaling in vivo would be extremely useful. By applying chemical inducer of dimerization (CID) technology, we were able to modify the Wnt co-receptor, low-density lipoprotein (LDL)-receptor-related protein 5 (LRP5), to generate the synthetic ligand inducible Wnt switch, iLRP5. We show that iLRP5 oligomerization results in its localization to disheveled-containing punctate structures and sequestration of scaffold protein Axin, leading to robust β-catenin-mediated signaling. Moreover, we identify a novel LRP5 cytoplasmic domain critical for its intracellular localization and casein kinase 1-dependent β-catenin signaling. Finally, by utilizing iLRP5 as a Wnt signaling switch, we generated the Ubiquitous Activator of β-catenin (Ubi-Cat) transgenic mouse line. The Ubi-Cat line allows for nearly ubiquitous expression of iLRP5 under control of the H-2Kb promoter. Activation of iLRP5 in isolated prostate basal epithelial stem cells resulted in expansion of p63+ cells and development of hyperplasia in reconstituted murine prostate grafts. Independently, iLRP5 induction in adult prostate stroma enhanced prostate tissue regeneration. Moreover, induction of iLRP5 in male Ubi-Cat mice resulted in prostate tumor progression over several months from prostate hyperplasia to adenocarcinoma. We also investigated iLRP5 activation in Ubi-Cat-derived mammary cells, observing that prolonged activation results in mammary tumor formation. Thus, in two distinct experimental mouse models, activation of iLRP5 results in disruption of tissue homeostasis, demonstrating the utility of iLRP5 as a novel research tool for determining the outcome of Wnt activation in a precise spatially and temporally determined fashion

The Atacama Cosmology Telescope: A Measurement of the DR6 CMB Lensing Power Spectrum and its Implications for Structure Growth

We present new measurements of cosmic microwave background (CMB) lensing over $9400$ sq. deg. of the sky. These lensing measurements are derived from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) CMB dataset, which consists of five seasons of ACT CMB temperature and polarization observations. We determine the amplitude of the CMB lensing power spectrum at $2.3\%$ precision ($43\sigma$ significance) using a novel pipeline that minimizes sensitivity to foregrounds and to noise properties. To ensure our results are robust, we analyze an extensive set of null tests, consistency tests, and systematic error estimates and employ a blinded analysis framework. The baseline spectrum is well fit by a lensing amplitude of $A_{\mathrm{lens}}=1.013\pm0.023$ relative to the Planck 2018 CMB power spectra best-fit $\Lambda$CDM model and $A_{\mathrm{lens}}=1.005\pm0.023$ relative to the $\text{ACT DR4} + \text{WMAP}$ best-fit model. From our lensing power spectrum measurement, we derive constraints on the parameter combination $S^{\mathrm{CMBL}}_8 \equiv \sigma_8 \left({\Omega_m}/{0.3}\right)^{0.25}$ of $S^{\mathrm{CMBL}}_8= 0.818\pm0.022$ from ACT DR6 CMB lensing alone and $S^{\mathrm{CMBL}}_8= 0.813\pm0.018$ when combining ACT DR6 and Planck NPIPE CMB lensing power spectra. These results are in excellent agreement with $\Lambda$CDM model constraints from Planck or $\text{ACT DR4} + \text{WMAP}$ CMB power spectrum measurements. Our lensing measurements from redshifts $z\sim0.5$--$5$ are thus fully consistent with $\Lambda$CDM structure growth predictions based on CMB anisotropies probing primarily $z\sim1100$. We find no evidence for a suppression of the amplitude of cosmic structure at low redshiftsComment: 45+21 pages, 50 figures. Prepared for submission to ApJ. Also see companion papers Madhavacheril et al and MacCrann et a