Antarctic krill (Euphausia superba) are considered a keystone species for higher trophic level predators along the West Antarctic Peninsula (WAP) during the austral summer. The connectivity of krill ...may play a critical role in predator biogeography, especially for central-place foragers such as the Pygoscelis spp. penguins that breed along the WAP during the austral summer. Antarctic krill are also heavily fished commercially; therefore, understanding population connectivity of krill is critical to effective management. Here, we used a physical ocean model to examine adult krill connectivity in this region using simulated krill with realistic diel vertical migration behaviors across four austral summers. Our results indicate that krill north and south of Low Island and the southern Bransfield Strait are nearly isolated from each other and that persistent current features play a role in this lack of inter-region connectivity. Transit and entrainment times were not correlated with penguin populations at the large spatial scales examined. However, long transit times and reduced entrainment correlate spatially with the areas where krill fishing is most intense, which heightens the risk that krill fishing may lead to limited krill availability for predators.
Bacteria from the genus Polaromonas are dominant phylotypes in clone libraries and culture collections from polar and high-elevation environments. Although Polaromonas has been found on six ...continents, we do not know if the same phylotypes exist in all locations or if they exhibit genetic isolation by distance patterns. To examine their biogeographic distribution, we analyzed all available, long-read 16S rRNA gene sequences of Polaromonas phylotypes from glacial and periglacial environments across the globe. Using genetic isolation by geographic distance analyses, including Mantel tests and Mantel correlograms, we found that Polaromonas phylotypes are globally distributed showing weak isolation by distance patterns at global scales. More focused analyses using discrete, equally sampled distances classes, revealed that only two distance classes (out of 12 total) showed significant spatial structuring. Overall, our analyses show that most Polaromonas phylotypes are truly globally distributed, but that some, as yet unknown, environmental variable may be selecting for unique phylotypes at a minority of our global sites. Analyses of aerobiological and genomic data suggest that Polaromonas phylotypes are globally distributed as dormant cells through high-elevation air currents; Polaromonas phylotypes are common in air and snow samples from high altitudes, and a glacial-ice metagenome and the two sequenced Polaromonas genomes contain the gene hipA, suggesting that Polaromonas can form dormant cells.
As the U.S. Congress has steadily evolved since the Founding of our nation, so too has our understanding of the institution. The second edition of New Directions in Congressional Politics offers an ...accessible overview of the current developments in our understanding of America's legislative branch. Jamie L. Carson and Michael S. Lynch help students bridge the gap between roles, rules, and outcomes by focusing on a variety of thematic issues: the importance of electoral considerations, legislators' strategic behavior to accomplish objectives, the unique challenges of Congress as a bicameral institution in a polarized environment, and the often-overlooked policy outputs of the institution.
This book brings together leading scholars of Congress to provide a general overview of the entire field. Each chapter covers the cutting-edge developments on its respective topic. As the political institution responsible for enacting laws, the American public regularly looks to the U.S. Congress to address the important issues of the day. The contributors in this volume help explain why staying atop the research trends helps us better understand these issues in the ever-changing field of American politics.
New to the Second Edition
New and updated chapters highlighting party recruitment, redistricting, women in Congress, the nationalization of Congressional elections, and the reassertion of Congressional oversight.
A first look at Congressional-executive relations in the Trump era.
Updated data through the 2018 Midterm elections.
Studies of solar radio bursts play an important role in understanding the dynamics and acceleration processes behind solar space weather events, and the influence of solar magnetic activity on solar ...system planets. Similar low-frequency bursts detected from active M-dwarfs are expected to probe their space weather environments and therefore the habitability of their planetary companions. Active M-dwarfs produce frequent, powerful flares which, along with radio emission, reveal conditions within their atmospheres. However, to date, only one candidate solar-like coherent radio burst has been identified from these stars, preventing robust observational constraints on their space weather environment. During simultaneous optical and radio monitoring of the nearby dM5.5e star Proxima Centauri, we detected a bright, long-duration optical flare, accompanied by a series of intense, coherent radio bursts. These detections include the first example of an interferometrically detected coherent stellar radio burst temporally coincident with a flare, strongly indicating a causal relationship between these transient events. The polarization and temporal structure of the trailing long-duration burst enable us to identify it as a type IV burst. This represents the most compelling detection of a solar-like radio burst from another star to date. Solar type IV bursts are strongly associated with space weather events such as coronal mass ejections and solar energetic particle events, suggesting that stellar type IV bursts may be used as a tracer of stellar coronal mass ejections. We discuss the implications of this event for the occurrence of coronal mass ejections from Proxima Cen and other active M-dwarfs.
Preclinical studies of human immunodeficiency virus type 1 (HIV-1) vaccine candidates have typically shown post-infection virological control, but protection against acquisition of infection has ...previously only been reported against neutralization-sensitive virus challenges. Here we demonstrate vaccine protection against acquisition of fully heterologous, neutralization-resistant simian immunodeficiency virus (SIV) challenges in rhesus monkeys. Adenovirus/poxvirus and adenovirus/adenovirus-vector-based vaccines expressing SIV(SME543) Gag, Pol and Env antigens resulted in an 80% or greater reduction in the per-exposure probability of infection against repetitive, intrarectal SIV(MAC251) challenges in rhesus monkeys. Protection against acquisition of infection showed distinct immunological correlates compared with post-infection virological control and required the inclusion of Env in the vaccine regimen. These data demonstrate the proof-of-concept that optimized HIV-1 vaccine candidates can block acquisition of stringent, heterologous, neutralization-resistant virus challenges in rhesus monkeys.
Background: Recombinant human platelet‐derived growth factor (rhPDGF) is safe and effective for the treatment of periodontal defects in short‐term studies up to 6 months in duration. We now provide ...results from a 36‐month extension study of a multicenter, randomized, controlled clinical trial evaluating the effect and long‐term stability of PDGF‐BB treatment in patients with localized severe periodontal osseous defects.
Methods: A total of 135 participants were enrolled from six clinical centers for an extension trial. Eighty‐three individuals completed the study at 36 months and were included in the analysis. The study investigated the local application of β‐tricalcium phosphate scaffold matrix with or without two different dose levels of PDGF (0.3 or 1.0 mg/mL PDGF‐BB) in patients possessing one localized periodontal osseous defect. Composite analysis for clinical and radiographic evidence of treatment success was defined as percentage of cases with clinical attachment level (CAL) ≥2.7 mm and linear bone growth (LBG) ≥1.1 mm.
Results: The participants exceeding this composite outcome benchmark in the 0.3 mg/mL rhPDGF‐BB group went from 62.2% at 12 months, 75.9% at 24 months, to 87.0% at 36 months compared with 39.5%, 48.3%, and 53.8%, respectively, in the scaffold control group at these same time points (P <0.05). Although there were no significant increases in CAL and LBG at 36 months among all groups, there were continued increases in CAL gain, LBG, and percentage bone fill over time, suggesting overall stability of the regenerative response.
Conclusion: PDGF‐BB in a synthetic scaffold matrix promotes long‐term stable clinical and radiographic improvements as measured by composite outcomes for CAL gain and LBG for patients possessing localized periodontal defects (ClinicalTrials.gov no. CT01530126).
Marine pollution is becoming ubiquitous in the environment. Observations of pollution on beaches, in the coastal ocean, and in organisms in the Antarctic are becoming distressingly common. Increasing ...human activity, growing tourism, and an expanding krill fishing industry along the West Antarctic Peninsula all represent potential sources of plastic pollution and other debris (collectively referred to as debris) to the region. However, the sources of these pollutants from point (pollutants released from discrete sources) versus non-point (pollutants from a large area rather than a specific source) sources are poorly understood. We used buoyant simulated particles released in a high-resolution physical ocean model to quantify pollutant loads throughout the region. We considered non-point sources of debris from the Antarctic Circumpolar Current, Bellingshausen Sea, Weddell Sea, and point source pollution from human activities including tourism, research, and fishing. We also determined possible origins for observed debris based on data from the Southern Ocean Observing System and Palmer Long-Term Ecological Research program. Our results indicate that point source pollution released in the coastal Antarctic is more likely to serve as a source for observed debris than non-point sources, and that the dominant source of pollution is region-specific. Penguin colonies in the South Shetland and Elephant Islands had the greatest debris load from point sources whereas loads from non-point sources were greatest around the southernmost colonies. Penguin colonies at Cornwallis Island and Fort Point were exposed to the highest theoretical debris loads. While these results do not include physical processes such as windage and Stokes Drift that are known to impact debris distributions and transport in the coastal ocean, these results provide critical insights to building an effective stratified sampling and monitoring effort to better understand debris distributions, concentrations, and origins throughout the West Antarctic Peninsula.
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•Marine debris are an emerging threat to Antarctic coastlines and local wildlife.•Simulated buoyant debris released in coastal areas remained in the coastal ocean.•Penguin colonies in the South Shetland Islands may be exposed to high debris loads.•Observed debris in coastal ocean likely originated from coastal human activities.•Model improvements and systematic surveys of marine debris will improve predictions.
Increasingly, local governments are crafting policy to tackle climate change. This article examines why cities develop and implement climate change programs. The authors consider the impact of ...interest group pressure, political institutions, and problem severity on a city’s decision to develop and implement climate protection programs. Their results suggest that organized interests influence both adoption and implementation of climate mitigation programs. This effect, however, is contingent on political institutions. In general, organized interests are more effective in mayoral as opposed to city manager forms of governments. Interestingly, while financially strapped cities may adopt climate mitigation programs to advance cobenefits or cost savings, fiscal stress also impedes program implementation.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic, resulting millions of infections and deaths with few effective interventions available. Here, we demonstrate ...that SARS-CoV-2 evades interferon (IFN) activation in respiratory epithelial cells, resulting in a delayed response in bystander cells. Since pretreatment with IFNs can block viral infection, we reasoned that pharmacological activation of innate immune pathways could control SARS-CoV-2 infection. To identify potent antiviral innate immune agonists, we screened a panel of 75 microbial ligands that activate diverse signaling pathways and identified cyclic dinucleotides (CDNs), canonical STING agonists, as antiviral. Since CDNs have poor bioavailability, we tested the small molecule STING agonist diABZI, and found that it potently inhibits SARS-CoV-2 infection of diverse strains including variants of concern (B.1.351) by transiently stimulating IFN signaling. Importantly, diABZI restricts viral replication in primary human bronchial epithelial cells and in mice in vivo. Our study provides evidence that activation of STING may represent a promising therapeutic strategy to control SARS-CoV-2.
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