271 research outputs found
Holocene Geology and Migration of a Low-Profile Barrier Island System, Metompkin Island, Virginia
Analysis of historical shoreline position, cross-island profile change, and stratigraphic data provided a shoreline response model for low-profile barrier island systems. Historical shoreline data illustrates continuous, shore-parallel retreat between 1852 and 1957, at which time the island narrowed to a width of approximately 200 m. Between 1957 and 1981, ephemeral inlet breaching along southern Metompkin Island disrupted longshore sediment transport, increased the rate of shoreline recession, and resulted in differential rates of retreat associated with an abrupt break in backbarrier morphology. By 1981, a 400 m offset had formed at a position midway along Metompkin Island, suggesting that ephemeral inlet processes were the primary mechanisms for accelerated migration rates along the southern island shoreline segment. More recently, a two-year island profiling study (11/83 to 11/85) showed significant deficits of sand along northern Metompkin Island and small additions along the southern island segment. Washover was the primary sand source to landward profile segments during recession, supporting the concept of barrier rollover.
Sediment deposits of the barrier island system include thick sequences of fine-grained, bioturbated backbarrier material that are capped by 0.6- to 2-m thick marsh deposits along northern Metompkin Island and by finely laminated sand to bioturbated silty sand units, associated with inlet sedimentation in Metompkin Bay. Configurations of the pre-Holocene surface affected the distribution of coastal lithosomes. Lagoonal mud thickens to the east and south towards a prominent antecedent valley associated with Folly Creek.
A model describing the late Holocene depositional history of the Metompkin Island system starts with a period of relative shoreline stability when fine-grained deposition was dominant throughout the back-barrier system. Between 1859 and 1887, formation of the Fishing Point spit complex significantly reduced the magnitude of longshore transport to the beach along Metompkin Island. Consequently, the rate of shoreline recession increased and the island narrowed. When island width decreased to approximately 200 m, inlet breaching was frequent along bay-backed southern Metompkin Island, increasing the rate of shoreline retreat. The primary mechanism by which the northern marsh-backed shoreline segment migrated landward was washover
Provenance study of late Eocene arkosic sandstones in southwest and central Washington
The purpose of this study is to compare the sandstone composition and trace element geochemistry between samples representing the Summit Creek sandstone, Naches, Chumstick, and Carbonado Formations in order to determine if these sediments were all derived from the same provenance, and to determine the composition of the source rocks in hopes to identify the present day location of the source areas
Diagnostic Role of Chromosomal Instability in Melanoma
Early diagnosis gives melanoma patients the best chance for long term survival. However discrimination of an early melanoma from an unusual/atypical benign nevus can represent a significant challenge. There are no current pathological markers to definitively define malignant potential in these indeterminate lesions. Thus, there is a need for improved diagnostic tools. Chromosomal instability (CIN) is a hallmark of cancer and is markedly prevalent in melanoma. Advances in genomics have opened the door for the development of molecular tools to better segregate benign and malignant lesions. This paper focuses on CIN in melanoma and the role of current diagnostic approaches
The Geology of Kansas—Arbuckle Group
Cambrian-Ordovician Arbuckle Group rocks in Kansas occur entirely in the subsurface. As is demonstrated throughout this paper, the historical and current understanding of the Arbuckle Group rocks in Kansas has in large part been dependent on petroleum-industry philosophies, practices, and trends. The widely accepted conceptual model of Arbuckle reservoirs as an unconformity play guided drilling and completion practices in which wells were drilled into the top of the Arbuckle with relatively short penetration (under 10 to 50 ft) deeper into the Arbuckle. This resulted in very little log or core data available from the Arbuckle interval. In addition, due to the early development (1917-1940) of the majority of Arbuckle reservoirs, log and geophysical data are not up to modern standards. Over the last few decades, deep penetrating wells have been drilled into the Arbuckle accompanied by full modern log suites and drill-stem tests. However, little corresponding core has been taken to calibrate the logs, and no detailed studies have been conducted to date on the more extensive, modern log data. Thus, data and detailed understanding of Arbuckle Group strata in Kansas are lacking relative to Arbuckle and age-equivalent strata from other areas in the United States, especially those where Arbuckle strata crop out. However, Arbuckle Group strata remain an important reservoir target in Kansas, and our understanding of the unit will increase with continued studies that incorporate modern data, techniques, and approaches
Primordial black holes with an accurate QCD equation of state
Making use of definitive new lattice computations of the Standard Model thermodynamics during the quantum chromodynamic (QCD) phase transition, we calculate the enhancement in the mass distribution of primordial black holes (PBHs) due to the softening of the equation of state. We find that the enhancement peaks at approximately 0.7 M-circle dot, with the formation rate increasing by at least two orders of magnitude due to the softening of the equation of state at this time, with a range of approximately 0.3 M-circle dot <M <1.4 M-circle dot at full width half-maximum. PBH formation is increased by a smaller amount for PBHs with masses spanning a large range, 10(-3) M-circle dot <M-PBH <10(3) M-circle dot, which includes the masses of the BHs that LIGO detected. The most significant source of uncertainty in the number of PBHs formed is now due to unknowns in the formation process, rather than from the phase transition. A near scale-invariant density power spectrum tuned to generate a population with mass and merger rate consistent with that detected by LIGO should also produce a much larger energy density of PBHs with solar mass. The existence of BHs below the Chandresekhar mass limit would be a smoking gun for a primordial origin and they could arguably constitute a significant fraction of the cold dark matter density. They also pose a challenge to infiationary model building which seek to produce the LIGO BHs without overproducing lighter PBHs.Peer reviewe
Germ Cell Proteins in Melanoma: Prognosis, Diagnosis, Treatment, and Theories on Expression
Germ cell protein expression in melanoma has been shown to correlate with malignancy, severity of disease and to serve as an immunologic target for therapy. However, very little is known about the role that germ cell proteins play in cancer development. Unique germ cell pathways include those involved in immortalization, genetic evolution, and energy metabolism. There is an ever increasing recognition that within tumors there is a subpopulation of cells with stem-cell-like characteristics that play a role in driving tumorgenesis. Stem cell and germ cell biology is intertwined. Given the enormous potential and known expression of germ cell proteins in melanoma, it is possible that they represent a largely untapped resource that may play a fundamental role in tumor development and progression. The purpose of this paper is to provide an update on the current value of germ cell protein expression in melanoma diagnosis, prognosis, and therapy, as well as to review critical germ cell pathways and discuss the potential roles these pathways may play in malignant transformation
From fat droplets to floating forests: cross-domain transfer learning using a PatchGAN-based segmentation model
Many scientific domains gather sufficient labels to train machine algorithms
through human-in-the-loop techniques provided by the Zooniverse.org citizen
science platform. As the range of projects, task types and data rates increase,
acceleration of model training is of paramount concern to focus volunteer
effort where most needed. The application of Transfer Learning (TL) between
Zooniverse projects holds promise as a solution. However, understanding the
effectiveness of TL approaches that pretrain on large-scale generic image sets
vs. images with similar characteristics possibly from similar tasks is an open
challenge. We apply a generative segmentation model on two Zooniverse
project-based data sets: (1) to identify fat droplets in liver cells
(FatChecker; FC) and (2) the identification of kelp beds in satellite images
(Floating Forests; FF) through transfer learning from the first project. We
compare and contrast its performance with a TL model based on the COCO image
set, and subsequently with baseline counterparts. We find that both the FC and
COCO TL models perform better than the baseline cases when using >75% of the
original training sample size. The COCO-based TL model generally performs
better than the FC-based one, likely due to its generalized features. Our
investigations provide important insights into usage of TL approaches on
multi-domain data hosted across different Zooniverse projects, enabling future
projects to accelerate task completion.Comment: 5 pages, 4 figures, accepted for publication at the Proceedings of
the ACM/CIKM 2022 (Human-in-the-loop Data Curation Workshop
Potential Role of Meiosis Proteins in Melanoma Chromosomal Instability
Melanomas demonstrate chromosomal instability (CIN). In fact, CIN can be used to differentiate melanoma from benign nevi. The exact molecular mechanisms that drive CIN in melanoma have yet to be fully elucidated. Cancer/testis antigens are a unique group of germ cell proteins that are found to be primarily expressed in melanoma as compared to benign nevi. The abnormal expression of these germ cell proteins, normally expected only in the testis and ovaries, in somatic cells may lead to interference with normal cellular pathways. Germ cell proteins that may be particularly critical in CIN are meiosis proteins. Here, we review pathways unique to meiosis with a focus on how the aberrant expression of meiosis proteins in normal mitotic cells “meiomitosis” could impact chromosomal instability in melanoma and other cancers
Feasibility of Harbor-wide Barrier Systems: Preliminary Analysis for Boston Harbor
The aim of this study is to provide the City of Boston with a preliminary assessment of the feasibilities and potential benefits, costs, and environmental impacts of three harborwide barrier configurations.
While this study is not comprehensive, and there are many ways that further research could refine and extend its findings, those findings were clear enough to justify making recommendations for next steps. The authors recommend that the City continue to focus its climate resilience strategy for the next several decades on the shore-based multi-layered approach described in Climate Ready Boston. Shore-based solutions would provide flood management more quickly at a lower cost, offer several key advantages over a harbor-wide barrier, and provide more flexibility in adapting and responding to changing conditions, technological innovations, and new information about global sea level rise. These shore-based solutions would be needed in any case over the next few decades to manage coastal flooding during the design and construction period of a harbor-wide barrier if a decision was made to build one in the future
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