Clonal diversity in an expanding community of Arctic Salix spp. and a model for recruitment modes of arctic plants

Rapid climate change in arctic environments is leading to a widespread expansion in woody deciduous shrub populations. However, little is known about the reproductive, dispersal, and establishment mechanisms associated with shrub expansion. It is assumed that harsh environmental conditions impose limitations on plant sexual reproduction in the Arctic, such that population survival and expansion is predominately a function of clonal recruitment. We present contrary evidence from microsatellite genetic data suggesting the prevalence of recruitment by seed. Further, we present a conceptual model describing modes of recruitment in relation to the abiotic environment. Climate change may be alleviating abiotic stress so that resources are available for more frequent recruitment by seed. Such changes have widespread implications for ecosystem structure and functioning, including species composition, wildlife habitat, biogeochemical cycling, and surface energy balance. © 2010 Regents of the University of Colorado

The relevance of the content of an HIV and AIDS social intervention programme for the youth in the Northern Cape, South Africa

The numbers of people infected with HIV and living with AIDS remain high in South Africa. The youth of the Northern Cape province in South Africa are a vulnerable population in this regard. However, there seems to be a dearth of rigorous evaluations of HIV and AIDS social intervention programmes targeted at the youth. This study aimed to evaluate the relevance of the content of an HIV and AIDS social intervention programme for the youth in the Northern Cape as well as to collect attendees’ recommendations with regards to programme content. The data collection method comprised a group-administered questionnaire completed by youth (N = 172) who participated in the Soul City social intervention programme (SCP) implemented for the youth in the Northern Cape, and recruited through stratified random sampling. Based on specific criteria, the results showed that the SCP programme’s content was relevant to the communities it served. The youth also forwarded recommendations for the programme content. Recommendations from the study include that youth support should be beyond dialogues; women’s rights should be promoted within the context of HIV prevention strategies; the SCP should intensify its condom promotion efforts because it is relevant to the South African government’s macro-level plan; relevant community leaders should be visited to explain the rationale for the youth’s involvement in programmes; and the programme should focus more pertinently on poverty alleviation strategies.http://www.www.tandfonline.com/toc/raar202020-10-01hj2019Social Work and Criminolog

Hydrological, Sedimentological, and Meteorological Observations and Analysis on the Sagavanirktok River

The Dalton Highway near Deadhorse was closed twice during late March and early April 2015 because of extensive overflow from the Sagavanirktok River that flowed over the highway. That spring, researchers from the Water and Environmental Research Center at the University of Alaska Fairbanks (UAF) monitored the river conditions during breakup, which was characterized by unprecedented flooding that overtopped and consequently destroyed several sections of the Dalton Highway near Deadhorse. The UAF research team has monitored breakup conditions at the Sagavanirktok River since that time. Given the magnitude of the 2015 flooding, the Alyeska Pipeline Service Company started a long-term monitoring program within the river basin. In addition, the Alaska Department of Transportation and Public Facilities (ADOT&PF) funded a multiyear project related to sediment transport conditions along the Sagavanirktok River. The general objectives of these projects include determining ice elevations, identifying possible water sources, establishing surface hydro-meteorological conditions prior to breakup, measuring hydro-sedimentological conditions during breakup and summer, and reviewing historical imagery of the aufeis extent. In the present report, we focus on new data and analyze it in the context of previous data. We calculated and compared ice thickness near Franklin Bluffs for 2015, 2016, and 2017, and found that, in general, ice thickness during both 2015 and 2016 was greater than in 2017 across most of the study area. Results from a stable isotope analysis indicate that winter overflow, which forms the aufeis in the river area near Franklin Bluffs, has similar isotopic characteristics to water flowing from mountain springs. End-of-winter snow surveys (in 2016/2017) within the watershed indicate that the average snow water equivalent was similar to what we observed in winter 2015/2016. Air temperatures in May 2017 were low on the Alaska North Slope, which caused a long and gradual breakup, with peak flows occurring in early June, compared with mid-May in both 2015 and 2016. Maximum discharge measured at the East Bank station, near Franklin Bluffs was 750 m3/s (26,485 ft3/s) on May 30, 2017, while the maximum measured flow was 1560 m3/s (55,090 ft3/s) at the same station on May 20, 2015. Available cumulative rainfall data indicate that 2016 was wetter than 2017. ii In September 2015, seven dry and wet pits were dug near the hydro-sedimentological monitoring stations along the Sagavanirktok River study reach. The average grain-size of the sediment of exposed gravel bars at sites located upstream of the Ivishak-Sagavanirktok confluence show relatively constant values. Grain size becomes finer downstream of the confluence. We conducted monthly topo-bathymetric surveys during the summer months of 2016 and 2017 in each pit. Sediment deposition and erosion was observed in each of the pits. Calculated sedimentation volumes in each pit show the influence of the Ivishak River in the bed sedimenttransport capacity of the Sagavanirktok River. In addition, comparison between dry and wet pit sedimentation volumes in some of the stations proves the complexity of a braided river, which is characterized by frequent channel shifting A two-dimensional hydraulic model is being implemented for a material site. The model will be used to estimate the required sediment refill time based on different river conditions.ABSTRACT ..................................................................................................................................... i LIST OF FIGURES ......................................................................................................................... i LIST OF TABLES ....................................................................................................................... xiv ACKNOWLEDGMENTS AND DISCLAIMER ........................................................................ xvi CONVERSION FACTORS, UNITS, WATER QUALITY UNITS, VERTICAL AND HORIZONTAL DATUM, ABBREVIATIONS, AND SYMBOLS .......................................... xvii ABBREVIATIONS, ACRONYMS, AND SYMBOLS .............................................................. xix 1 INTRODUCTION ................................................................................................................... 1 2 STUDY AREA ........................................................................................................................ 2 2.1 Sagavanirktok River near MP318 Site 066 (DSS4) ......................................................... 7 2.2 Sagavanirktok River at Happy Valley Site 005 (DSS3) .................................................. 7 2.3 Sagavanirktok River below the Confluence with the Ivishak River (DSS2) ................... 9 2.4 Sagavanirktok River near MP405 Site 042 (DSS1) ....................................................... 10 3 METHODOLOGY AND EQUIPMENT .............................................................................. 13 3.1 Pits .................................................................................................................................. 13 3.1.1 Excavation............................................................................................................... 13 3.1.2 Surveying ................................................................................................................ 14 3.2 Surface Meteorology ...................................................................................................... 15 3.3 Aufeis Extent .................................................................................................................. 17 3.3.1 Field Methods ......................................................................................................... 18 3.3.2 Imagery ................................................................................................................... 18 3.4 Water Level Measurements ............................................................................................ 19 3.5 Runoff............................................................................................................................. 20 3.6 Suspended Sediment ...................................................................................................... 21 3.7 Turbidity ......................................................................................................................... 22 3.8 Stable Isotopes................................................................................................................ 22 4 RESULTS .............................................................................................................................. 23 4.1 Meteorology ................................................................................................................... 23 4.1.1 Air Temperature ...................................................................................................... 23 4.1.2 Precipitation ............................................................................................................ 31 4.1.2.1 Cold Season Precipitation ................................................................................ 31 4.1.2.2 Warm Season Precipitation ............................................................................. 36 4.1.3 Wind Speed and Direction ...................................................................................... 39 iv 4.2 Aufeis Extent .................................................................................................................. 40 4.2.1 Historical Aufeis at Franklin Bluffs ........................................................................ 41 4.2.2 Delineating Ice Surface Elevation with GPS and Aerial Imagery .......................... 45 4.3 Surface Water Hydrology ............................................................................................... 52 4.3.1 Sagavanirktok River at MP318 (DSS4) .................................................................. 58 4.3.2 Sagavanirktok River at Happy Valley (DSS3) ....................................................... 61 4.3.3 Sagavanirktok River near MP347 (ASS1) .............................................................. 65 4.3.4 Sagavanirktok River below the Ivishak River (DSS2) ........................................... 66 4.3.5 Sagavanirktok River at East Bank (DSS5) near Franklin Bluffs ............................ 70 4.3.6 Sagavanirktok River at MP405 (DSS1) West Channel .......................................... 78 4.3.7 Additional Field Observations ................................................................................ 82 4.3.8 Preliminary Rating Curves and Estimated Discharge ............................................. 85 4.4 Stable Isotopes................................................................................................................ 86 4.5 Sediment Grain Size Distribution .................................................................................. 90 4.5.1 Streambed Sediment Grain Size Distribution ......................................................... 90 4.5.2 Suspended Sediment Grain Size Distribution ......................................................... 94 4.6 Suspended Sediment Concentration ............................................................................... 95 4.6.1 Sagavanirktok River near MP318 (DSS4) .............................................................. 95 4.6.2 Sagavanirktok River at Happy Valley (DSS3) ..................................................... 100 4.6.3 Sagavanirktok River below the Ivishak River (DSS2) ......................................... 105 4.6.4 Sagavanirktok River near MP405 (DSS1) ............................................................ 111 4.6.5 Discussion ............................................................................................................. 114 4.7 Turbidity ....................................................................................................................... 116 4.7.1 Sagavanirktok River near MP318 (DSS4) ............................................................ 116 4.7.2 Sagavanirktok River at Happy Valley (DSS3) ..................................................... 119 4.7.3 Sagavanirktok River below the Ivishak (DSS2) ................................................... 124 4.7.4 Sagavanirktok River near MP405 (DSS1) ............................................................ 126 4.7.5 Discussion ............................................................................................................. 130 4.8 Analysis of Pits............................................................................................................. 130 4.8.1 Photographs of Pits ............................................................................................... 130 4.8.2 GIS Analysis of Pit Bathymetry ........................................................................... 141 4.8.3 Pit Sedimentation .................................................................................................. 142 4.8.4 Erosion Surveys .................................................................................................... 149 4.8.5 Patterns of Sediment Transport Along the River .................................................. 156 v 4.9 Hydraulic Modeling ..................................................................................................... 158 4.9.1 Model Development .............................................................................................. 160 4.9.2 Results of Simulation ............................................................................................ 165 5 CONCLUSIONS ................................................................................................................. 171 6 REFERENCES .................................................................................................................... 174 7 APPENDICES ..................................................................................................................... 18

Eurasian Arctic greening reveals teleconnections and the potential for novel ecosystems

Arctic warming has been linked to observed increases in tundra shrub cover and growth in recent decades on the basis of significant relationships between deciduous shrub growth/biomass and temperature. These vegetation trends have been linked to Arctic sea ice decline and thus to the sea ice/albedo feedback known as Arctic amplification. However, the interactions between climate, sea ice and tundra vegetation remain poorly understood. Here we reveal a 50- year growth response over a >100,000 km2 area to a rise in summer temperature for alder (Alnus) and willow (Salix), the most abundant shrub genera respectively at and north of the continental treeline. We demonstrate that whereas plant productivity is related to sea ice in late spring, the growing season peak responds to persistent synoptic-scale air masses over West Siberia associated with Fennoscandian weather systems through the Rossby wave train. Substrate is important for biomass accumulation, yet a strong correlation between growth and temperature encompasses all observed soil types. Vegetation is especially responsive to temperature in early summer. These results have significant implications for modelling present and future Low Arctic vegetation responses to climate change, and emphasize the potential for structurally novel ecosystems to emerge fromwithin the tundra zone.Vertaisarviointia edeltävä käsikirjoitu

Oncogenic PIK3CA corrupts growth factor signaling specificity

Pathological activation of the PI3K/AKT pathway is among the most frequent defects in human cancer and is also the cause of rare overgrowth disorders. Yet, there is currently no systematic understanding of the quantitative flow of information within PI3K/AKT signaling and how it is perturbed by disease-causing mutations. Here, we develop scalable, single-cell approaches for systematic analyses of signal processing within the PI3K pathway, enabling precise calculations of its information transfer for different growth factors. Using genetically-engineered human cell models with allele dose-dependent expression of PIK3CAH1047R, we show that this oncogene is not a simple, constitutive pathway activator but a context-dependent modulator of extracellular signal transfer. PIK3CAH1047Rreduces information transmission downstream of IGF1 while selectively enhancing EGF-induced signaling and transcriptional responses. This leads to a gross reduction in signaling specificity, akin to “blurred” signal perception. The associated increase in signaling heterogeneity promotes phenotypic diversity in a human cervical cancer cell line model and in human induced pluripotent stem cells. Collectively, these findings and the accompanying methodological advances lay the foundations for a systematic mapping of the quantitative mechanisms of PI3K/AKT-dependent signal processing and phenotypic control in health and disease

Dynamics of earthquake nucleation process represented by the Burridge-Knopoff model

Dynamics of earthquake nucleation process is studied on the basis of the one-dimensional Burridge-Knopoff (BK) model obeying the rate- and state-dependent friction (RSF) law. We investigate the properties of the model at each stage of the nucleation process, including the quasi-static initial phase, the unstable acceleration phase and the high-speed rupture phase or a mainshock. Two kinds of nucleation lengths L_sc and L_c are identified and investigated. The nucleation length L_sc and the initial phase exist only for a weak frictional instability regime, while the nucleation length L_c and the acceleration phase exist for both weak and strong instability regimes. Both L_sc and L_c are found to be determined by the model parameters, the frictional weakening parameter and the elastic stiffness parameter, hardly dependent on the size of an ensuing mainshock. The sliding velocity is extremely slow in the initial phase up to L_sc, of order the pulling speed of the plate, while it reaches a detectable level at a certain stage of the acceleration phase. The continuum limits of the results are discussed. The continuum limit of the BK model lies in the weak frictional instability regime so that a mature homogeneous fault under the RSF law always accompanies the quasi-static nucleation process. Duration times of each stage of the nucleation process are examined. The relation to the elastic continuum model and implications to real seismicity are discussed.Comment: Title changed. Changes mainly in abstract and in section 1. To appear in European Physical Journal

Summer warming explains widespread but not uniform greening in the Arctic tundra biome

Arctic warming can influence tundra ecosystem function with consequences for climate feedbacks, wildlife and human communities. Yet ecological change across the Arctic tundra biome remains poorly quantified due to field measurement limitations and reliance on coarse-resolution satellite data. Here, we assess decadal changes in Arctic tundra greenness using time series from the 30 m resolution Landsat satellites. From 1985 to 2016 tundra greenness increased (greening) at ~37.3% of sampling sites and decreased (browning) at ~4.7% of sampling sites. Greening occurred most often at warm sampling sites with increased summer air temperature, soil temperature, and soil moisture, while browning occurred most often at cold sampling sites that cooled and dried. Tundra greenness was positively correlated with graminoid, shrub, and ecosystem productivity measured at field sites. Our results support the hypothesis that summer warming stimulated plant productivity across much, but not all, of the Arctic tundra biome during recent decades

Acute-Phase-HDL Remodeling by Heparan Sulfate Generates a Novel Lipoprotein with Exceptional Cholesterol Efflux Activity from Macrophages

During episodes of acute-inflammation high-density lipoproteins (HDL), the carrier of so-called good cholesterol, experiences a major change in apolipoprotein composition and becomes acute-phase HDL (AP-HDL). This altered, but physiologically important, HDL has an increased binding affinity for macrophages that is dependent on cell surface heparan sulfate (HS). While exploring the properties of AP-HDL∶HS interactions we discovered that HS caused significant remodeling of AP-HDL. The physical nature of this change in structure and its potential importance for cholesterol efflux from cholesterol-loaded macrophages was therefore investigated. In the presence of heparin, or HS, AP-HDL solutions at pH 5.2 became turbid within minutes. Analysis by centrifugation and gel electrophoresis indicated that AP-HDL was remodeled generating novel lipid poor particles composed only of apolipoprotein AI, which we designate β2. This remodeling is dependent on pH, glycosaminoglycan type, is promoted by Ca2+ and is independent of protease or lipase activity. Compared to HDL and AP-HDL, remodeled AP-HDL (S-HDL-SAA), containing β2 particles, demonstrated a 3-fold greater cholesterol efflux activity from cholesterol-loaded macrophage. Because the identified conditions causing this change in AP-HDL structure and function can exist physiologically at the surface of the macrophage, or in its endosomes, we postulate that AP-HDL contains latent functionalities that become apparent and active when it associates with macrophage cell surface/endosomal HS. In this way initial steps in the reverse cholesterol transport pathway are focused at sites of injury to mobilize cholesterol from macrophages that are actively participating in the phagocytosis of damaged membranes rich in cholesterol. The mechanism may also be of relevance to aspects of atherogenesis