Statistical evidence links exceptional 1995 Atlantic hurricane season to record sea warming

Tropical cyclones rank above earthquakes as the major geophysical cause of loss of life and property (Bryant, 1991; Houghton, 1994). In the United States alone, the damage bill from mainland landfalling hurricanes over the last 50 years averages $2.0 billion per year (Hebert et al., 1996). Years with high numbers of hurricanes provide new insight on the environmental factors influencing interannual variability; hence the interest in the exceptional 1995 Atlantic season which saw 11 hurricanes and a total of 19 tropical storms, double the 50-year average. While most environmental factors in 1995 were favourable for tropical cyclone development, we show that a factor not fully explored before, the sea surface temperature (SST) was the most significant. For the 10 degrees-20 degrees N, 20 degrees-60 degrees W region where 93% of the anomalous 1995 hurricanes developed, similar to 45 year statistical regressions show that SST is the dominating influence, independent of all known other factors, behind the interannual variance in Atlantic hurricance numbers. With this SST experiencing record warm levels in 1995, 0.66 degrees C above the 1946-1995 mean, these regressions indicate that sea warming explains 61+/-34% of the anomalous hurricane activity in 1995 to 95% confidence

Out of sight but no longer out of mind: A climate of change for marine conservation in Madagascar

With over 5,500 km of coastline spanning more than 14 degrees of latitude, Madagascar boasts a diversity of marine and coastal habitats that is unrivalled in the Indian Ocean. These ecosystems are of paramount importance to national food security, as well as the livelihoods and culture of coastal people. Yet Madagascar’s fragile marine resources are facing unprecedented threats from climate change, habitat destruction and overfishing. Development of an ecologically robust national marine protected area network presents the only viable means of safeguarding the resilience of remaining healthy ecosystems. But in the current post - crisis context, characterised by a lack of fully functional national environmental governance institutions, severe funding gaps and pervasive coastal poverty, conventional centralised approaches to marine protected area planning and management are unable to respond effectively to the scale and immediacy of the challenge. Given these constraints, the ongoing expansion of local coastal governance efforts will be key to promoting socially viable adaptive management strategies. Encouragingly, the recent rapid growth and scaling - up of locally managed marine areas (LMMAs) in Madagascar is unsurpassed throughout east Africa and the Indian Ocean region, with communities pioneering new and innovative approaches to fisheries management and livelihood diversification. The durability of such local conservation efforts, however, will depend on their capacity to demonstrate the economic as well as biodiversity benefits of sustainable marine resource management. This challenge necessitates placing a renewed focus on proving, quantifying and communicating the utilitarian benefits of marine biodiversity. Making this business case will be a fundamental prerequisite to stemming the tide of marine environmental degradation in Madagascar, and tackling the twin tragedies of coastal poverty and the marine commons

From the mechanical properties of single cells to those of simple tissues

As interest in biophysics and biophysical modelling has grown in the cell and developmental biology communities, a variety of techniques have been developed to measure the mechanical properties of single cells. Atomic Force Microscopy (AFM) has become one of the preferred methods for these measurements primarily due to its ease of operation and commercial availability. However, measurements on soft cells with a variable surface topography require an additional level of care so that the predicted contact area with the cell surface is accurately estimated. Using combined AFM and confocal microscopy I have shown that with pyramidal tipped cantilevers the cell body can easily deform to the shape of the tip but can also touch the underside of the AFM cantilever beam causing an overestimation of elasticity. Such artefactual increases in contact area could be avoided by using spherical tipped cantilevers or tips with a high aspect ratio. I examined the role of the cytoskeleton and cell contractility in setting single cell stiffness with AFM. With techniques such as AFM, the rheology of single cells is becoming increasingly well characterised. The next logical step in furthering our understanding of organ and embryo mechanics is to scale up investigations to simple tissues such as on cell thick monolayers. I have developed methods to measure the mechanical properties of MDCK epithelial cell monolayers under AFM indentation or planar extension. Using deep indentation of monolayers cultured on soft gels I have measured the evolution of mechanical properties upon the establishment of cell-cell junctions. The relative mechanical stiffnesses of monolayer-gel composites evolve as cell contacts are established and required the formation of mature contractile adherens junctions. To measure the planar mechanical properties of cell monolayers I designed a system to create monolayers freely suspended from their susbstrate between two test rods. Cell monolayers have a higher stiffness than their cellular constituents due to the organisation of the cell cytoskeleton upon the formation of matured intercellular junctions

Complexity of Bradley-Manna-Sipma Lexicographic Ranking Functions

In this paper we turn the spotlight on a class of lexicographic ranking functions introduced by Bradley, Manna and Sipma in a seminal CAV 2005 paper, and establish for the first time the complexity of some problems involving the inference of such functions for linear-constraint loops (without precondition). We show that finding such a function, if one exists, can be done in polynomial time in a way which is sound and complete when the variables range over the rationals (or reals). We show that when variables range over the integers, the problem is harder -- deciding the existence of a ranking function is coNP-complete. Next, we study the problem of minimizing the number of components in the ranking function (a.k.a. the dimension). This number is interesting in contexts like computing iteration bounds and loop parallelization. Surprisingly, and unlike the situation for some other classes of lexicographic ranking functions, we find that even deciding whether a two-component ranking function exists is harder than the unrestricted problem: NP-complete over the rationals and $\Sigma^P_2$-complete over the integers.Comment: Technical report for a corresponding CAV'15 pape

Aircraft measurements of the latitudinal, vertical, and seasonal variations of NMHCs, methyl nitrate, methyl halides, and DMS during the First Aerosol Characterization Experiment (ACE 1)

Canister sampling for the determination of atmospheric mixing ratios of nonmethane hydrocarbons (NMHCs), selected halocarbons, and methyl nitrate was conducted aboard the National Center for Atmospheric Research (NCAR) C-130 aircraft over the Pacific and Southern Oceans as part of the First Aerosol Characterization Experiment (ACE 1) during November and December 1995. A latitudinal profile, flown from 76°N to 60°S, revealed latitudinal gradients for most trace gases. NMHC and halocarbon gases with predominantly anthropogenic sources, including ethane, ethyne, and tetrachloroethene, exhibited significantly higher mixing ratios in the northern hemisphere at all altitudes. Methyl chloride exhibited its lowest mixing ratios at the highest northern hemisphere latitudes, and the distributions of methyl nitrate and methyl iodide were consistent with tropical and subtropical oceanic sources. Layers containing continental air characteristic of aged biomass burning emissions were observed above about 3 km over the remote southern Pacific and near New Zealand between approximately 19°S and 43°S. These plumes originated from the west, possibly from fires in southern Africa. The month-long intensive investigation of the clean marine southern midlatitude troposphere south of Australia revealed decreases in the mixing ratios of ethane, ethyne, propane, and tetrachloroethene, consistent with their seasonal mixing ratio cycle. By contrast, increases in the average marine boundary layer concentrations of methyl iodide, methyl nitrate, and dimethyl sulfide (DMS) were observed as the season progressed to summer conditions. These increases were most appreciable in the region south of 44°S over Southern Ocean waters characterized as subantarctic and polar, indicating a seasonal increase in oceanic productivity for these gases. Copyright 1999 by the American Geophysical Union

The effects of two weeks high-intensity interval training on fasting glucose, glucose tolerance and insulin resistance in adolescent boys: a pilot study

This is the final version. Available on open access from BMC via the DOI in this recordAvailability of data and materials: The datasets generated and analysed during the current study are not publicly available due to ethical restrictions but are available from the corresponding author upon reasonable request.Background Current evidence of metabolic health benefits of high-intensity interval training (HIIT) are limited to longer training periods or conducted in overweight youth. This study assessed 1) fasting and postprandial insulin and glucose before and after 2 weeks of HIIT in healthy adolescent boys, and 2) the relationship between pre intervention health outcomes and the effects of the HIIT intervention. Methods Seven healthy boys (age:14.3 ± 0.3 y, BMI: 21.6 ± 2.6, 3 participants classified as overweight) completed 6 sessions of HIIT over 2 weeks. Insulin resistance (IR) and blood glucose and insulin responses to a Mixed Meal Tolerance Test (MMTT) were assessed before (PRE), 20 h and 70 h after (POST) the final HIIT session. Results Two weeks of HIIT had no effect on fasting plasma glucose, insulin or IR at 20 h and 70 h POST HIIT, nor insulin and glucose response to MMTT (all P > 0.05). There was a strong negative correlation between PRE training IR and change in IR after HIIT (r = − 0.96, P < 0.05). Conclusion Two weeks of HIIT did not elicit improvements to fasting or postprandial glucose or insulin health outcomes in a group of adolescent boys. However the negative correlation between PRE IR and improvements after HIIT suggest that interventions of this type may be effective in adolescents with raised baseline IR.National Institute for Health Research (NIHR)Northcott Devon Medical Foundatio

Formation of adherens junctions leads to the emergence of a tissue-level tension in epithelial monolayers.

Adherens junctions and desmosomes interface the cytoskeletons of adjacent cells into a mechanical syncitium. In doing so, intercellular junctions endow tissues with the strength needed to sustain mechanical stresses encountered in normal physiology and coordinate tension during morphogenesis. Though much is known about the biological mechanisms underlying junction formation, little is known about how tissue-scale mechanical properties are established. Here, we use deep AFM indentation to measure the apparent stiffness of epithelial monolayers reforming from dissociated cells and examine which cellular processes give rise to tissue-scale mechanics. We show that the formation of intercellular junctions coincided with an increase in the apparent stiffness of reforming monolayers that reflected the generation of a tissue-level tension. Tension rapidly increased reaching a maximum after 150 minutes before settling to a lower level over the next three hours as monolayers reached homeostasis. The emergence of tissue tension correlated with the formation of adherens junctions but not desmosomes. As a consequence, inhibition of any of the molecular mechanisms participating in adherens junction initiation, remodelling, and maturation significantly impeded the emergence of tissue-level tension in monolayers

The effect of windspeed on sea surface temperature retrieval from space

The effect of windspeed on water emissivity, whilst being negligible around normal incidence, becomes significant above angles of about 50-degrees. We calculate the effect of windspeed On retrieved sea surface temperature and show that errors become significant for the potentially very accurate Along Track Scanning Radiometer (ATSR, carried on board ESA's first remote sensing satellite, ERS-1) since brightness temperatures measured at almost-equal-to 56-degrees, as well as those measured at nadir, are used to provide improved atmospheric correction. We show that when an SST retrieval algorithm generated assuming zero windspeed is applied to brightness temperatures calculated for windspeeds of 5, 10 and 15 m/s, a potential error of up to 0.4 K is introduced. Since coincident windspeed data can be obtained from the ERS-1 radar altimeter, accurate correction can be made for this effect and we Provide a Preliminary algorithm for the correction of ATSR SST data

Simulating Reionization: Character and Observability

In recent years there has been considerable progress in our understanding of the nature and properties of the reionization process. In particular, the numerical simulations of this epoch have made a qualitative leap forward, reaching sufficiently large scales to derive the characteristic scales of the reionization process and thus allowing for realistic observational predictions. Our group has recently performed the first such large-scale radiative transfer simulations of reionization, run on top of state-of-the-art simulations of early structure formation. This allowed us to make the first realistic observational predictions about the Epoch of Reionization based on detailed radiative transfer and structure formation simulations. We discuss the basic features of reionization derived from our simulations and some recent results on the observational implications for the high-redshift Ly-alpha sources.Comment: 3 pages, to appear in the Proceedings of First Stars III, Santa Fe, July 2007, AIP Conference Serie

Emergence of homeostatic epithelial packing and stress dissipation through divisions oriented along the long cell axis.

Cell division plays an important role in animal tissue morphogenesis, which depends, critically, on the orientation of divisions. In isolated adherent cells, the orientation of mitotic spindles is sensitive to interphase cell shape and the direction of extrinsic mechanical forces. In epithelia, the relative importance of these two factors is challenging to assess. To do this, we used suspended monolayers devoid of ECM, where divisions become oriented following a stretch, allowing the regulation and function of epithelial division orientation in stress relaxation to be characterized. Using this system, we found that divisions align better with the long, interphase cell axis than with the monolayer stress axis. Nevertheless, because the application of stretch induces a global realignment of interphase long axes along the direction of extension, this is sufficient to bias the orientation of divisions in the direction of stretch. Each division redistributes the mother cell mass along the axis of division. Thus, the global bias in division orientation enables cells to act collectively to redistribute mass along the axis of stretch, helping to return the monolayer to its resting state. Further, this behavior could be quantitatively reproduced using a model designed to assess the impact of autonomous changes in mitotic cell mechanics within a stretched monolayer. In summary, the propensity of cells to divide along their long axis preserves epithelial homeostasis by facilitating both stress relaxation and isotropic growth without the need for cells to read or transduce mechanical signals.We thank D. Farquharson and S. Townsend at the University College London workshop and Joel Jennings and Richard Adams for help with model development. B.B. and J.B. thank Cancer Research UK, the Biotechnology and Biological Sciences Research Council (BBSRC) (Grant BB/K009001), the French Institut National du Cancer, and Matthieu Piel for support. T.P.J.W. and A.D. were supported by the Engineering and Physical Sciences Research Council. A.R.H. was supported by the BBSRC (Grant BB/K013521 to G.C. and A.K.), and M.L. was supported by the Agency for Science Technology and Research (Singapore) and the Wellcome Trust.This is the accepted manuscript of a paper published in the Proceedings of the National Academy of Sciences (Wyatt et al., PNAS 2015, 112, 18, 5726-5731, doi:10.1073/pnas.1420585112). The final version is available at http://dx.doi.org/10.1073/pnas.142058511