The response of temperature to CO
2
change (climate sensitivity) in the geologic past may help inform future climate predictions. Proxies for CO
2
and temperature generally imply high climate ...sensitivities: ≥3 K per CO
2
doubling during ice-free times (fast-feedback sensitivity) and ≥6 K during times with land ice (Earth-system sensitivity). Climate models commonly underpredict the magnitude of climate change and have fast-feedback sensitivities close to 3 K. A better characterization of feedbacks in warm worlds raises climate sensitivity to values more in line with proxies and produces climate simulations that better fit geologic evidence. As CO
2
builds in our atmosphere, we should expect both slow (e.g., land ice) and fast (e.g., vegetation, clouds) feedbacks to elevate the long-term temperature response over that predicted from the canonical fast-feedback value of 3 K. Because temperatures will not decline for centuries to millennia, climate sensitivities that integrate slower processes have relevance for current climate policy.
Many palaeoclimate studies have quantified pre-anthropogenic climate change to calculate climate sensitivity (equilibrium temperature change in response to radiative forcing change), but a lack of ...consistent methodologies produces a wide range of estimates and hinders comparability of results. Here we present a stricter approach, to improve intercomparison of palaeoclimate sensitivity estimates in a manner compatible with equilibrium projections for future climate change. Over the past 65 million years, this reveals a climate sensitivity (in K W(-1) m(2)) of 0.3-1.9 or 0.6-1.3 at 95% or 68% probability, respectively. The latter implies a warming of 2.2-4.8 K per doubling of atmospheric CO(2), which agrees with IPCC estimates.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Many key aspects of early angiosperms are poorly known, including their ecophysiology and associated habitats. Evidence for fast-growing, weedy angiosperms comes from the Early Cretaceous Potomac ...Group, where angiosperm fossils, some of them putative herbs, are found in riparian depositional settings. However, inferences of growth rate from sedimentology and growth habit are somewhat indirect; also, the geographic extent of a weedy habit in early angiosperms is poorly constrained. Using a power law between petiole width and leaf mass, we estimated the leaf mass per area (LMA) of species from three Albian (110–105 Ma) fossil floras from North America (Winthrop Formation, Patapsco Formation of the Potomac Group, and the Aspen Shale). All LMAs for angiosperm species are low (<125 g/m 2 ; mean = 76 g/m 2 ) but are high for gymnosperm species (>240 g/m 2 ; mean = 291 g/m 2 ). On the basis of extant relationships between LMA and other leaf economic traits such as photosynthetic rate and leaf lifespan, we conclude that these Early Cretaceous landscapes were populated with weedy angiosperms with short-lived leaves (<12 mo). The unrivalled capacity for fast growth observed today in many angiosperms was in place by no later than the Albian and likely played an important role in their subsequent ecological success.
The theory and use of geochemical modeling of the long-term carbon cycle and four paleo-PCO2 proxies are reviewed and discussed in order to discern the best applications for each method. Geochemical ...models provide PCO2 predictions for the entire Phanerozoic, but most existing models present 5-10 m.y. means, and so often do not resolve short-term excursions.
Reading a CO2 Signal from Fossil Stomata Beerling, D. J.; Royer, D. L.
New phytologist,
March 2002, Letnik:
153, Številka:
3
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The inverse relationship between atmospheric CO2 and the stomatal index (proportion of epidermal cells that are stomata) of vascular land plant leaves has led to the use of fossil plant cuticles for ...determining ancient levels of CO2. In contemporary plants the stomatal index repeatedly shows a lower sensitivity atmospheric CO2 levels above 340 ppm in the short term. These observations demonstrate that the phenotypic response is nonlinear and may place constraints on estimating higher-than-present palaeo- CO2 levels in this way. We review a range of evidence to investigate the nature of this nonlinearity. Our new data, from fossil Ginkgo cuticles, suggest that the genotypic response of fossil Ginkgo closely tracks the phenotypic response seen in CO2 enrichment experiments. Reconstructed atmospheric CO2 values from fossil Ginkgo cuticles compare well with the stomatal ratio method of obtaining a quantitative CO2 signal from extinct fossil plants, and independent geochemical modelling studies of the long-term carbon cycle. Although there is self-consistency between palaeobiological and geochemical CO2 estimates, it should be recognized that the nonlinear response is a limitation of the stomatal approach to estimating high palaeo- CO2 levels.
Trapeziometacarpal arthroplasty is a well-known treatment of thumb basal joint arthritis. However, only a few studies have been done on its use specifically in men, with one of the most recent ...showing a high implant failure rate. Our study was a retrospective analysis of the ISIS prosthesis exclusively in men. Our hypothesis was that it is a viable therapeutic solution. Between 2010 and 2020, 23 ISIS prostheses were implanted in 19 patients. A radiological and functional analysis was done, combined with a self-evaluation by multiple validated outcome scores (visual analog scale for pain, QuickDASH, PRWE, SF36, and Kapandji scores). The median follow-up was 76 months (13–134) with a median age of 69 years. The mean pain level was 1/10, the QuickDASH was 22.7, the PRWE was 14.2, the SF-36 was 61.1 and the Kapandji score was 8.9. One dislocation occurred in one patient; two patients had to be reoperated for periprosthetic ossifications. Radiolucency was found around the cup in one patient and around the metacarpal shaft in one patient. There was no implant failure and only one case of asymptomatic loosening, with a survival rate of 94% at 111 months. In the medium-term, clinical, and functional outcomes were satisfactory with pain relief similar to that of published studies, with a low rate of complications. ISIS arthroplasty appears to be a suitable treatment for thumb basal joint arthritis in men, although a non-negligible rate of periprosthetic ossifications required revision surgery in half of the cases.
L’arthroplastie trapézo-métacarpienne est un traitement reconnu de la rhizarthrose, mais dont l’évaluation spécifique chez l’homme a été peu étudiée, avec une des séries les plus récentes montrant un important taux de faillite de l’implant. Notre étude consistait en une analyse rétrospective de la prothèse ISIS exclusivement chez les hommes. Notre hypothèse était que celle-ci constitue une solution thérapeutique viable. Entre 2010 et 2020, 23 prothèses ISIS ont été implantées chez 19 hommes. Une analyse radiologique et fonctionnelle a été réalisée, associée à une auto-évaluation par de multiples questionnaires validés (évaluation visuelle analogique de la douleur, scores QuickDASH, PRWE, S-36, de Kapandji pour l’opposition). Le recul médian était de 76 mois (13–134) avec un âge médian de 69 ans. Nous notions une douleur à 1/10, des scores QuickDASH à 22,7, PRWE 14,2, SF-36 à 61,1 et de Kapandji à 8,9. Nous relevions une luxation de prothèse et deux reprises chirurgicales pour ossifications périprothétiques. Un liseré autour de la cupule était présent chez un patient, autour de la tige métacarpienne chez 4 patients. Nous n’avons pas trouvé de faillite de l’implant, un seul cas de descellement asymptomatique, avec un taux de survie de 94,1% à 111 mois. Nous rapportons une satisfaction clinique, fonctionnelle et une indolence à moyen terme comparables à cellesdu reste de la littérature, associées à un faible taux de complications. La prothèse ISIS nous apparait comme une thérapeutique adaptée de la rhizarthrose chez l’homme, avec toutefois un taux non négligeable d‘ossifications périprothétiques imposant une reprise chirurgicale dans la moitié des cas.
Abstract
Designing integrated circuits in radiation environments such as the High Luminosity LHC (HL-LHC) is challenging.
Integrated circuits will be exposed to radiation-induced Single Event Effects ...(SEE).
In deep sub-micron technology devices, the impact of SEEs can be mitigated by triple modular redundancy.
The triplication of the most sensitive data is used to recover most of the data corruption induced by interacting particles.
One type of SEE, called single event upset (SEU), is studied in this paper. The SEU cross-section and the
performance of the triplication are estimated using an ASIC prototype exposed to a beam of protons.
The SEU cross-section is measured and systematic difference between 1→0 and 0→1 bit flip rates is observed. The efficiency of the mitigation method is investigated.
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