Toward quantifying the increasing role oceanic heat in sea ice loss in the new Arctic

Author Posting. © American Meteorological Society, 2015. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 96 (2015): 2079–2105, doi:10.1175/BAMS-D-13-00177.1.The loss of Arctic sea ice has emerged as a leading signal of global warming. This, together with acknowledged impacts on other components of the Earth system, has led to the term “the new Arctic.” Global coupled climate models predict that ice loss will continue through the twenty-first century, with implications for governance, economics, security, and global weather. A wide range in model projections reflects the complex, highly coupled interactions between the polar atmosphere, ocean, and cryosphere, including teleconnections to lower latitudes. This paper summarizes our present understanding of how heat reaches the ice base from the original sources—inflows of Atlantic and Pacific Water, river discharge, and summer sensible heat and shortwave radiative fluxes at the ocean/ice surface—and speculates on how such processes may change in the new Arctic. The complexity of the coupled Arctic system, and the logistic and technological challenges of working in the Arctic Ocean, require a coordinated interdisciplinary and international program that will not only improve understanding of this critical component of global climate but will also provide opportunities to develop human resources with the skills required to tackle related problems in complex climate systems. We propose a research strategy with components that include 1) improved mapping of the upper- and middepth Arctic Ocean, 2) enhanced quantification of important process, 3) expanded long-term monitoring at key heat-flux locations, and 4) development of numerical capabilities that focus on parameterization of heat-flux mechanisms and their interactions.2016-06-0

Cache coherence requirements for interprocess rendezvous

Multiprocessors in which a shared bus is used by the processor to communicate with common memory are an emerging class of machines where there is a need to support parallel programming languages. A language construct that is found in a number of parallel programming languages to support synchronization and communication in the interprocess rendezvous. Shared-bus multiprocessor require a protocol to keep the date in their caches coherent. There are two major categories of these protocols: invalidation and write-boadcast. This paper examines the requirements for cache coherence protocols to support efficient interprocessor rendezvous. The approach taken is to examine the memory referencing patterns to the run-time data structures during rendezvous execution. The appropriate coherence protocol is shown to be a function of the processor scheduling strategy used by the run-time system at synchronzation points during the rendezvous. When processes migrate freely as a result of the scheduling strategy, invalidation protocols are found to be more efficient. When migration is restricted by the scheduler, write-broadcast protocols are more efficient.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44571/1/10766_2005_Article_BF01407863.pd

Cache Coherence Requirements for Interprocess Rendezvous

Multiprocessors in which a shared bus is used by the processors to com-municate with common memory are an emerging class of machines where there is a need to support parallel programming languages. A language construct that is found in a number of parallel programming languages to support syn-chronization and communication in the interprocess rendezvous. Shared-bus multiprocessors require a protocol to keep the date in their caches coherent. There are two major categories of these protocols: invalidation and write-broad-cast. This paper examines the requirements for cache coherence protocols to support efficient interprocessor rendezvous. The approach taken is to examine the memory referencing patterns to the run-time data structures during rendez-vous execution. The appropriate coherence protocol is shown to be a function of the processor scheduling strategy used by the run-time system at synchroniza-tion points during the rendezvous. When processes migrate freely as a result of the scheduling strategy, invalidation protocols are found to he more eff When migration is restricted by the scheduler, write-broadcast protocols are more efficient. KEY WORDS: Cache coherence; rendezvous; run-time systems; process migration; concurrent programming languages. 1

Preemptive Circular Defence of Immature Insects: Definition and Occurrences of Cycloalexy Revisited

AbstractCycloalexy was coined by Vasconcellos-Neto and Jolivet in 1988 and further defined by Jolivet and collaborators in 1990 in reference to a specific type of circular defence. The term has been applied to numerous organisms, including adult insects, nymphs, and even vertebrates, but has lost precision with the accumulation of anecdotal reports not addressing key elements of the behaviour as first defined. We review the literature and propose three criteria that are sufficient and necessary to define the behaviour: (1) individuals form a circle; (2) defensive attributes of the individuals are positioned on the periphery of the circle, and as a result, the periphery of the circle uniformly contains either heads or abdomens; (3) animals preemptively adopt the circle as a resting formation, meaning it is not necessary to observe predation. When these considerations are taken into account, cycloalexy appears less common in nature than the literature suggests. We argue that unequivocal cases of cycloalexy have been found only in sawflies (Tenthredinoidea: Pergidae, Argidae), leaf beetles (Chrysolemidae: Galerucinae, Cassidinae, Chrysomelinae, Criocerinae), weevils (Curculionidae: Phelypera distigma), and midges (Diptera: Ceratopogonidae, Forcipomyia). Reports of cycloalexy in caterpillars (Saturniidae: Hemileucinae: Lonomia, Papilionidae) require further documentation. We report one new case of cycloalexy in thrips (Thysanoptera) and question reports of cycloalexic behaviour in other taxa

Breath gas metabolites and bacterial metagenomes from cystic fibrosis airways indicate active pH neutral 2,3-butanedione fermentation.

The airways of cystic fibrosis (CF) patients are chronically colonized by patient-specific polymicrobial communities. The conditions and nutrients available in CF lungs affect the physiology and composition of the colonizing microbes. Recent work in bioreactors has shown that the fermentation product 2,3-butanediol mediates cross-feeding between some fermenting bacteria and Pseudomonas aeruginosa, and that this mechanism increases bacterial current production. To examine bacterial fermentation in the respiratory tract, breath gas metabolites were measured and several metagenomes were sequenced from CF and non-CF volunteers. 2,3-butanedione was produced in nearly all respiratory tracts. Elevated levels in one patient decreased during antibiotic treatment, and breath concentrations varied between CF patients at the same time point. Some patients had high enough levels of 2,3-butanedione to irreversibly damage lung tissue. Antibiotic therapy likely dictates the activities of 2,3-butanedione-producing microbes, which suggests a need for further study with larger sample size. Sputum microbiomes were dominated by P. aeruginosa, Streptococcus spp. and Rothia mucilaginosa, and revealed the potential for 2,3-butanedione biosynthesis. Genes encoding 2,3-butanedione biosynthesis were disproportionately abundant in Streptococcus spp, whereas genes for consumption of butanedione pathway products were encoded by P. aeruginosa and R. mucilaginosa. We propose a model where low oxygen conditions in CF lung lead to fermentation and a decrease in pH, triggering 2,3-butanedione fermentation to avoid lethal acidification. We hypothesize that this may also increase phenazine production by P. aeruginosa, increasing reactive oxygen species and providing additional electron acceptors to CF microbes