220 research outputs found
Storm-induced inner-continental shelf circulation and sediment transport : Long Bay, South Carolina
This paper is not subject to U.S. copyright. The definitive version was published in Continental Shelf Research 42 (2012): 51–63, doi:10.1016/j.csr.2012.05.001.Long Bay is a sediment-starved, arcuate embayment located along the US East Coast connecting both South and North Carolina. In this region the rates and pathways of sediment transport are important because they determine the availability of sediments for beach nourishment, seafloor habitat, and navigation. The impact of storms on sediment transport magnitude and direction were investigated during the period October 2003–April 2004 using bottom mounted flow meters, acoustic backscatter sensors and rotary sonars deployed at eight sites offshore of Myrtle Beach, SC, to measure currents, water levels, surface waves, salinity, temperature, suspended sediment concentrations, and bedform morphology. Measurements identify that sediment mobility is caused by waves and wind driven currents from three predominant types of storm patterns that pass through this region: (1) cold fronts, (2) warm fronts and (3) low-pressure storms. The passage of a cold front is accompanied by a rapid change in wind direction from primarily northeastward to southwestward. The passage of a warm front is accompanied by an opposite change in wind direction from mainly southwestward to northeastward. Low-pressure systems passing offshore are accompanied by a change in wind direction from southwestward to southeastward as the offshore storm moves from south to north.
During the passage of cold fronts more sediment is transported when winds are northeastward and directed onshore than when the winds are directed offshore, creating a net sediment flux to the north–east. Likewise, even though the warm front has an opposite wind pattern, net sediment flux is typically to the north–east due to the larger fetch when the winds are northeastward and directed onshore. During the passage of low-pressure systems strong winds, waves, and currents to the south are sustained creating a net sediment flux southwestward. During the 3-month deployment a total of 8 cold fronts, 10 warm fronts, and 10 low-pressure systems drove a net sediment flux southwestward. Analysis of a 12-year data record from a local buoy shows an average of 41 cold fronts, 32 warm fronts, and 26 low-pressure systems per year. The culmination of these events would yield a cumulative net inner-continental shelf transport to the south–west, a trend that is further verified by sediment textural analysis and bedform morphology on the inner-continental shelf.This research was funded by the South Carolina Coastal
Erosion Project(http://pubs.usgs.gov/fs/2005/3041/), a cooperative study supported by the US Geological Survey and the South
Carolina Sea Grant Consortium(Sea Grant Project no:R/CP-11)
Dihexyl-Substituted Poly(3,4-Propylenedioxythiophene) as a Dual Ionic and Electronic Conductive Cathode Binder for Lithium-Ion Batteries
The polymer binders used in most lithium-ion batteries (LIBs) serve only a structural role, but there are exciting opportunities to increase performance by using polymers with combined electronic and ionic conductivity. To this end, here we examine dihexyl-substituted poly(3,4-propylenedioxythiophene) (PProDOT-Hx₂) as an electrochemically stable π-conjugated polymer that becomes electrically conductive (up to 0.1 S cm⁻¹) upon electrochemical doping in the potential range of 3.2 to 4.5 V (vs Li/Li⁺). Because this family of polymers is easy to functionalize, can be effectively fabricated into electrodes, and shows mixed electronic and ionic conductivity, PProDOT-Hx₂ shows promise for replacing the insulating polyvinylidene fluoride (PVDF) commonly used in commercial LIBs. A combined experimental and theoretical study is presented here to establish the fundamental mixed ionic and electronic conductivity of PProDOT-Hx₂. Electrochemical kinetics and electron spin resonance are first used to verify that the polymer can be readily electrochemically doped and is chemically stable in a potential range of interest for most cathode materials. A novel impedance method is then used to directly follow the evolution of both the electronic and ionic conductivity as a function of potential. Both values increase with electrochemical doping and stay high across the potential range of interest. A combination of optical ellipsometry and grazing incidence wide angle X-ray scattering is used to characterize both solvent swelling and structural changes that occur during electrochemical doping. These experimental results are used to calibrate molecular dynamics simulations, which show improved ionic conductivity upon solvent swelling. Simulations further attribute the improved ionic conductivity of PProDOT-Hx₂ to its open morphology and the increased solvation is possible because of the oxygen-containing propylenedioxythiophene backbone. Finally, the performance of PProDOT-Hx₂ as a conductive binder for the well-known cathode LiNi_(0.8)Co_(0.15)Al_(0.05)O₂ relative to PVDF is presented. PProDOT-Hx₂-based cells display a fivefold increase in capacity at high rates of discharge compared to PVDF-based electrodes at high rates and also show improved long-term cycling stability. The increased rate capability and cycling stability demonstrate the benefits of using binders such as PProDOT-Hx₂, which show good electronic and ionic conductivity, combined with electrochemical stability over the potential range for standard cathode operation
Enhancer Remodeling during Adaptive Bypass to MEK Inhibition Is Attenuated by Pharmacologic Targeting of the P-TEFb Complex
Targeting the dysregulated BRaf-MEK-ERK pathway in cancer has increasingly emerged in clinical trial design. Despite clinical responses in specific cancers using inhibitors targeting BRaf and MEK, resistance develops often involving non-genomic adaptive bypass mechanisms. Inhibition of MEK1/2 by trametinib in triple negative breast cancer (TNBC) patients induced dramatic transcriptional responses, including upregulation of receptor tyrosine kinases (RTKs) comparing tumor samples before and after one week of treatment. In preclinical models MEK inhibition induced genome-wide enhancer formation involving the seeding of BRD4, MED1, H3K27 acetylation and p300 that drives transcriptional adaptation. Inhibition of P-TEFb associated proteins BRD4 and CBP/p300 arrested enhancer seeding and RTK upregulation. BRD4 bromodomain inhibitors overcame trametinib resistance, producing sustained growth inhibition in cells, xenografts and syngeneic mouse TNBC models. Pharmacological targeting of P-TEFb members in conjunction with MEK inhibition by trametinib is an effective strategy to durably inhibit epigenomic remodeling required for adaptive resistance
Advanced structural brain aging in preclinical autosomal dominant Alzheimer disease
BackgroundBrain-predicted age estimates biological age from complex, nonlinear features in neuroimaging scans. The brain age gap (BAG) between predicted and chronological age is elevated in sporadic Alzheimer disease (AD), but is underexplored in autosomal dominant AD (ADAD), in which AD progression is highly predictable with minimal confounding age-related co-pathology.MethodsWe modeled BAG in 257 deeply-phenotyped ADAD mutation-carriers and 179 non-carriers from the Dominantly Inherited Alzheimer Network using minimally-processed structural MRI scans. We then tested whether BAG differed as a function of mutation and cognitive status, or estimated years until symptom onset, and whether it was associated with established markers of amyloid (PiB PET, CSF amyloid-beta-42/40), phosphorylated tau (CSF and plasma pTau-181), neurodegeneration (CSF and plasma neurofilament-light-chain [NfL]), and cognition (global neuropsychological composite and CDR-sum of boxes). We compared BAG to other MRI measures, and examined heterogeneity in BAG as a function of ADAD mutation variants, APOE epsilon 4 carrier status, sex, and education.ResultsAdvanced brain aging was observed in mutation-carriers approximately 7 years before expected symptom onset, in line with other established structural indicators of atrophy. BAG was moderately associated with amyloid PET and strongly associated with pTau-181, NfL, and cognition in mutation-carriers. Mutation variants, sex, and years of education contributed to variability in BAG.ConclusionsWe extend prior work using BAG from sporadic AD to ADAD, noting consistent results. BAG associates well with markers of pTau, neurodegeneration, and cognition, but to a lesser extent, amyloid, in ADAD. BAG may capture similar signal to established MRI measures. However, BAG offers unique benefits in simplicity of data processing and interpretation. Thus, results in this unique ADAD cohort with few age-related confounds suggest that brain aging attributable to AD neuropathology can be accurately quantified from minimally-processed MRI
Staphylococcus aureus Surface Protein SdrE Binds Complement Regulator Factor H as an Immune Evasion Tactic
Similar to other highly successful invasive bacterial pathogens, Staphylococcus aureus recruits the complement regulatory protein factor H (fH) to its surface to inhibit the alternative pathway of complement. Here, we report the identification of the surface-associated protein SdrE as a fH-binding protein using purified fH overlay of S. aureus fractionated cell wall proteins and fH cross-linking to S. aureus followed by mass spectrometry. Studies using recombinant SdrE revealed that rSdrE bound significant fH whether from serum or as a purified form, in both a time- and dose-dependent manner. Furthermore, rSdrE-bound fH exhibited cofactor functionality for factor I (fI)-mediated cleavage of C3b to iC3b which correlated positively with increasing amounts of fH. Expression of SdrE on the surface of the surrogate bacterium Lactococcus lactis enhanced recruitment of fH which resulted in increased iC3b generation. Moreover, surface expression of SdrE led to a reduction in C3-fragment deposition, less C5a generation, and reduced killing by polymorphonuclear cells. Thus, we report the first identification of a S. aureus protein associated with the staphylococcal surface that binds factor H as an immune evasion mechanism
Impact of H1N1 on Socially Disadvantaged Populations: Systematic Review
The burden of H1N1 among socially disadvantaged populations is unclear. We aimed to synthesize hospitalization, severe illness, and mortality data associated with pandemic A/H1N1/2009 among socially disadvantaged populations.Studies were identified through searching MEDLINE, EMBASE, scanning reference lists, and contacting experts. Studies reporting hospitalization, severe illness, and mortality attributable to laboratory-confirmed 2009 H1N1 pandemic among socially disadvantaged populations (e.g., ethnic minorities, low-income or lower-middle-income economy countries [LIC/LMIC]) were included. Two independent reviewers conducted screening, data abstraction, and quality appraisal (Newcastle Ottawa Scale). Random effects meta-analysis was conducted using SAS and Review Manager.Sixty-two studies including 44,777 patients were included after screening 787 citations and 164 full-text articles. The prevalence of hospitalization for H1N1 ranged from 17-87% in high-income economy countries (HIC) and 11-45% in LIC/LMIC. Of those hospitalized, the prevalence of intensive care unit (ICU) admission and mortality was 6-76% and 1-25% in HIC; and 30% and 8-15%, in LIC/LMIC, respectively. There were significantly more hospitalizations among ethnic minorities versus non-ethnic minorities in two studies conducted in North America (1,313 patients, OR 2.26 [95% CI: 1.53-3.32]). There were no differences in ICU admissions (n = 8 studies, 15,352 patients, OR 0.84 [0.69-1.02]) or deaths (n = 6 studies, 14,757 patients, OR 0.85 [95% CI: 0.73-1.01]) among hospitalized patients in HIC. Sub-group analysis indicated that the meta-analysis results were not likely affected by confounding. Overall, the prevalence of hospitalization, severe illness, and mortality due to H1N1 was high for ethnic minorities in HIC and individuals from LIC/LMIC. However, our results suggest that there were little differences in the proportion of hospitalization, severe illness, and mortality between ethnic minorities and non-ethnic minorities living in HIC
Risk of COVID-19 death for people with a pre-existing cancer diagnosis prior to COVID-19-vaccination : A systematic review and meta-analysis
Research Funding National Health and Medical Research Council. Grant Number: APP1194679 World Health Organization Article Funding Open access publishing facilitated by The University of Sydney, as part of the Wiley - The University of Sydney agreement via the Council of Australian University Librarians.Peer reviewedPublisher PD
Risk of COVID-19 death for people with a pre-existing cancer diagnosis prior to COVID-19-vaccination:A systematic review and meta-analysis
While previous reviews found a positive association between pre-existing cancer diagnosis and COVID-19-related death, most early studies did not distinguish long-term cancer survivors from those recently diagnosed/treated, nor adjust for important confounders including age. We aimed to consolidate higher-quality evidence on risk of COVID-19-related death for people with recent/active cancer (compared to people without) in the pre-COVID-19-vaccination period. We searched the WHO COVID-19 Global Research Database (20 December 2021), and Medline and Embase (10 May 2023). We included studies adjusting for age and sex, and providing details of cancer status. Risk-of-bias assessment was based on the Newcastle-Ottawa Scale. Pooled adjusted odds or risk ratios (aORs, aRRs) or hazard ratios (aHRs) and 95% confidence intervals (95% CIs) were calculated using generic inverse-variance random-effects models. Random-effects meta-regressions were used to assess associations between effect estimates and time since cancer diagnosis/treatment. Of 23 773 unique title/abstract records, 39 studies were eligible for inclusion (2 low, 17 moderate, 20 high risk of bias). Risk of COVID-19-related death was higher for people with active or recently diagnosed/treated cancer (general population: aOR = 1.48, 95% CI: 1.36-1.61, I2 = 0; people with COVID-19: aOR = 1.58, 95% CI: 1.41-1.77, I2 = 0.58; inpatients with COVID-19: aOR = 1.66, 95% CI: 1.34-2.06, I2 = 0.98). Risks were more elevated for lung (general population: aOR = 3.4, 95% CI: 2.4-4.7) and hematological cancers (general population: aOR = 2.13, 95% CI: 1.68-2.68, I2 = 0.43), and for metastatic cancers. Meta-regression suggested risk of COVID-19-related death decreased with time since diagnosis/treatment, for example, for any/solid cancers, fitted aOR = 1.55 (95% CI: 1.37-1.75) at 1 year and aOR = 0.98 (95% CI: 0.80-1.20) at 5 years post-cancer diagnosis/treatment. In conclusion, before COVID-19-vaccination, risk of COVID-19-related death was higher for people with recent cancer, with risk depending on cancer type and time since diagnosis/treatment.</p
The global meningitis genome partnership.
Genomic surveillance of bacterial meningitis pathogens is essential for effective disease control globally, enabling identification of emerging and expanding strains and consequent public health interventions. While there has been a rise in the use of whole genome sequencing, this has been driven predominately by a subset of countries with adequate capacity and resources. Global capacity to participate in surveillance needs to be expanded, particularly in low and middle-income countries with high disease burdens. In light of this, the WHO-led collaboration, Defeating Meningitis by 2030 Global Roadmap, has called for the establishment of a Global Meningitis Genome Partnership that links resources for: N. meningitidis (Nm), S. pneumoniae (Sp), H. influenzae (Hi) and S. agalactiae (Sa) to improve worldwide co-ordination of strain identification and tracking. Existing platforms containing relevant genomes include: PubMLST: Nm (31,622), Sp (15,132), Hi (1935), Sa (9026); The Wellcome Sanger Institute: Nm (13,711), Sp (> 24,000), Sa (6200), Hi (1738); and BMGAP: Nm (8785), Hi (2030). A steering group is being established to coordinate the initiative and encourage high-quality data curation. Next steps include: developing guidelines on open-access sharing of genomic data; defining a core set of metadata; and facilitating development of user-friendly interfaces that represent publicly available data
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