A coupled carbon/climate model is used to explore the impact of Drake Passage opening and Central American Seaway closure on the distribution of carbon in the global oceans. We find that gateway ...evolution likely played an important role in setting the modern day distribution of oceanic dissolved inorganic carbon (DIC), which is currently characterized by relatively low concentrations in the Atlantic Ocean, and high concentrations in the Southern, Indian, and Pacific oceans. In agreement with previous studies, we find a closed Drake Passage in the presence of an open Central American Seaway results in suppressed Atlantic meridional overturning and enhanced southern hemispheric deep convection. Opening of the Drake Passage triggers Antarctic Circumpolar Current flow and a weak Atlantic meridional overturning circulation (AMOC). Subsequent Central American Seaway closure reinforces the AMOC while also stagnating equatorial Pacific subsurface waters. These gateway-derived oceanographic changes are reflected in large shifts to the global distribution of DIC. An initially closed Drake Passage results in high DIC concentrations in the Atlantic and Arctic oceans, and lower DIC concentrations in the Pacific/Indian/Southern oceans. Opening Drake Passage reverses this gradient by lowering mid-depth Atlantic and Arctic DIC concentrations and raising deep Pacific/Indian/Southern Ocean DIC concentrations. Central American Seaway closure further reinforces this trend through additional Atlantic mid-depth DIC decreases, as well as Pacific mid-depth DIC concentration increases, with the net effect being a transition to a modern distribution of oceanic DIC.
•Carbon/climate model used to explore ocean carbon response to gateway changes.•Drake Passage opening drives ocean carbon distribution towards modern state.•Central American closure reinforces Drake-Passage-derived trend.•Carbon response to gateway changes primarily related to circulation changes.
Nonlinearity of Carbon Cycle Feedbacks Zickfeld, Kirsten; Eby, Michael; Matthews, H. Damon ...
Journal of climate,
08/2011, Letnik:
24, Številka:
16
Journal Article
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Coupled climate–carbon models have shown the potential for large feedbacks between climate change, atmospheric CO₂ concentrations, and global carbon sinks. Standard metrics of this feedback assume ...that the response of land and ocean carbon uptake to CO₂ (concentration–carbon cycle feedback) and climate change (climate–carbon cycle feedback) combine linearly. This study explores the linearity in the carbon cycle response by analyzing simulations with an earth system model of intermediate complexity the University of Victoria Earth System Climate Model (UVic ESCM). The results indicate that the concentration–carbon and climate–carbon cycle feedbacks do not combine linearly to the overall carbon cycle feedback. In this model, the carbon sinks on land and in the ocean are less efficient when exposed to the combined effect of elevated CO₂ and climate change than to the linear combination of the two. The land accounts for about 80% of the nonlinearity, with the ocean accounting for the remaining 20%. On land, this nonlinearity is associated with the different response of vegetation and soil carbon uptake to climate in the presence or absence of the CO₂ fertilization effect. In the ocean, the nonlinear response is caused by the interaction of changes in physical properties and anthropogenic CO₂. These findings suggest that metrics of carbon cycle feedback that postulate linearity in the system’s response may not be adequate.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Determining the nature and source of hiring frictions is an important topic for policymakers, as these frictions impact both worker outcomes and economic growth. To date, there has been very little ...US‐based research that has combined detailed measures of employer skill requirements, market structure, organizational characteristics and hiring difficulties at the establishment level. Prior to this study, there has been almost no research that has investigated these issues in the context of a highly regulated industry such as healthcare, which employs more workers than either retail or manufacturing. Using a unique, nationally representative dataset, this study finds that organizational practices and market structure are more relevant predictors of hiring difficulties for laboratory technologists than factors, such as skill mismatch, that are often assumed to be of primary importance.
The question of what happens when a composer alters a poet's poetic cycle haunts examinations of many song cycles and has proven especially problematic for Robert Schumann's Dichterliebe. The ...long-held view that Schumann crafted a clear plot from Heine's non-narrative Lyrisches Intermezzo has recently been questioned in favour of a view of the cycle as an incoherent fragment. Using the tools of narratology, this article argues that Dichterliebe is both a fragment and a coherent whole, a string of memories held together by a distinct narrative logic. Identifying two poetic voices illuminates the cycle's narrative strategy and also sheds light on problematic aspects of the music, including Schumann's deletion of four songs, the voice-piano relationship and the enigmatic final postlude. This article proposes answers to age-old questions about Dichterliebe while also offering a fresh approach to the study of song cycles.
Vaccines for
have been of longstanding interest to immunologists, bacteriologists, and clinicians, due to the widespread prevalence of hospital-acquired infection. As
becomes increasingly antibiotic ...resistant, there is a dire need for novel treatments and preventive vaccines. Despite intense efforts, there currently remains no vaccine on the market to combat this dangerous pathogen. This article summarizes current and past vaccines under development that target various constituents of
. Targeting lipopolysaccharides and O-antigens have shown some promise in preventing infection. Recombinant flagella and pili that target TLR5 have been utilized to combat
by blocking its motility and adhesion. The type 3 secretion system components, such as needle-like structure PcrV or exotoxin PopB, are also potential vaccine targets. Outer membrane proteins including OprF and OprI are newer representatives of vaccine candidates. Live attenuated vaccines are a focal point in this review, and are also considered for novel vaccines. In addition, phage therapy is revived as an effective option for treating refractory infections after failure with antibiotic treatment. Many of the aforementioned vaccines act on a single target, thus lacking a broad range of protection. Recent studies have shown that mixtures of vaccines and combination approaches may significantly augment immunogenicity, thereby increasing their preventive and therapeutic potential.
In recent years, the viewing of reality television has
become increasingly prevalent among television audiences. However, little is
known about the psychological processes at work when viewing these ...programs.
This study examined how social comparisons to cast members influenced emotional
responses to reality television programming. Participants (N =
231) were cued with a specific comparison target group and placed in a situation
of self-image enhancement or threat. Afterwards, participants watched a clip
from a reality television program and then reported their emotional reactions to
it. The manipulations of comparison target group and self-image affected both
the direction of social comparisons made and their associated emotional
responses. Participant gender also influenced social comparisons to the cast
members and resulting emotional responses to the content. Although we were
unable to compare the social comparison-related emotional responses to reality
programs with those of scripted programs, the results of this study bring to
bear the associations between specific emotional responses and the types of
social comparisons that take place when watching reality television
programming.
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