Assessment of malaria transmission changes in Africa, due to the climate impact of land use change using Coupled Model Intercomparison Project Phase 5 earth system models

Using mathematical modelling tools, we assessed the potential for land use change (LUC) associated with the Intergovernmental Panel on Climate Change low- and high-end emission scenarios (RCP2.6 and RCP8.5) to impact malaria transmission in Africa. To drive a spatially explicit, dynamical malaria model, data from the four available earth system models (ESMs) that contributed to the LUC experiment of the Fifth Climate Model Intercomparison Project are used. Despite the limited size of the ESM ensemble, stark differences in the assessment of how LUC can impact climate are revealed. In three out of four ESMs, the impact of LUC on precipitation and temperature over the next century is limited, resulting in no significant change in malaria transmission. However, in one ESM, LUC leads to increases in precipitation under scenario RCP2.6, and increases in temperature in areas of land use conversion to farmland under both scenarios. The result is a more intense transmission and longer transmission seasons in the southeast of the continent, most notably in Mozambique and southern Tanzania. In contrast, warming associated with LUC in the Sahel region reduces risk in this model, as temperatures are already above the 25-30°C threshold at which transmission peaks. The differences between the ESMs emphasise the uncertainty in such assessments. It is also recalled that the modelling framework is unable to adequately represent local-scale changes in climate due to LUC, which some field studies indicate could be significant

Black Holes, Instanton Counting on Toric Singularities and q-Deformed Two-Dimensional Yang-Mills Theory

We study the relationship between instanton counting in N=4 Yang-Mills theory on a generic four-dimensional toric orbifold and the semi-classical expansion of q-deformed Yang-Mills theory on the blowups of the minimal resolution of the orbifold singularity, with an eye to clarifying the recent proposal of using two-dimensional gauge theories to count microstates of black holes in four dimensions. We describe explicitly the instanton contributions to the counting of D-brane bound states which are captured by the two-dimensional gauge theory. We derive an intimate relationship between the two-dimensional Yang-Mills theory and Chern-Simons theory on generic Lens spaces, and use it to show that the correct instanton counting is only reproduced when the Chern-Simons contributions are treated as non-dynamical boundary conditions in the D4-brane gauge theory. We also use this correspondence to discuss the counting of instantons on higher genus ruled Riemann surfaces.Comment: 27 page

Polymorphic Behavior of Copolymers of Syndiotactic Polystyrene with m-Methylstyrene.

The influence of the presence of different amounts m-methylstyrene (m-MS), in the composition range 4−21 mol %, on the polymorphic behavior of syndiotactic polystyrene (s-PS) is presented. A comparison with the effect of the presence of p-methylstyrene is also presented. The behavior of copolymers subjected to solvent extraction or annealing procedures indicates that the presence of m-MS stabilizes the γ form of s-PS, which remains stable in a large temperature range, up to 210−220 °C. The helical mesoporous δ form of s-PS has not been observed in copolymers with m-MS. The presence of low contents of m-MS induces crystallization of the β form from polymer solution (by casting at high temperatures), whereas high concentrations of m-MS tend to stabilize the γ form. The copolymer samples crystallize from the melt in α and β forms depending on the concentration of m-MS, which stabilizes the β form for composition around 11 mol %, and induces crystallization in the α form for lower (4 mol %) and higher (21 mol %) concentration. Moreover, even when the memory of the α form is maintained in the melt, the presence of m-MS in a concentration around 11 mol % induces the crystallization of the β form, whereas, even though no memory of the α form is present in the melt, samples with 4 and 21 mol % of m-MS crystallize in the α form. The α form obtained in these copolymers, by melt-crystallization or annealing of the γ form, does not correspond to neither the disordered α‘, nor the ordered α‘ ‘ modifications observed in s-PS. The presence of m-MS comonomeric units induces structural variation in the crystal packing of the trans-planar chains, and a new crystalline form is obtained

Inkjet printing of a polymeric vibration damper for MEMS application adopting a step-reticulation process

In the frame of additive manufacturing techniques, inkjet printing (IJP) has gained great attention both from the academic and industrial point of view, for its customization, cost-effectiveness and simplicity, in contrast to more traditional patterning techniques, i.e. lithography. IJP could be flanked in the industrial manufacturing of parts of MEMS. In particular, since MEMS are constituted of mechanical parts, they are subjected to undesired vibrations that can degrade the device. In particular, polymers are optimal material candidates for vibration damping applications. The idea of the work was to demonstrate the possibility to adopt IJP for the production of a polymeric vibration damping layer on a floating spring of a MEMS device. In depth characterization of the polymeric ink is provided as well as a jetting characterization that helped the optimization of the printing process. A common reported issue of IJP is the impossibility to reproduce perfectly vertical walls, due to drops spreading when impacting the substrate. We tried to tackle this issue by proposing an alternative process, improving the verticality of the printed pattern walls. Printing was transferred to patterned MEMS and device characterization is proposed, in terms of how the printed polymeric layer can alter or not the mechanical properties of the spring. The work highlights how IJP can be adopted to produce components of devices, avoiding the use of expensive techniques

Phase transitions, double-scaling limit, and topological strings

Topological strings on Calabi--Yau manifolds are known to undergo phase transitions at small distances. We study this issue in the case of perturbative topological strings on local Calabi--Yau threefolds given by a bundle over a two-sphere. This theory can be regarded as a q--deformation of Hurwitz theory, and it has a conjectural nonperturbative description in terms of q--deformed 2d Yang--Mills theory. We solve the planar model and find a phase transition at small radius in the universality class of 2d gravity. We give strong evidence that there is a double--scaled theory at the critical point whose all genus free energy is governed by the Painlev\'e I equation. We compare the critical behavior of the perturbative theory to the critical behavior of its nonperturbative description, which belongs to the universality class of 2d supergravity. We also give evidence for a new open/closed duality relating these Calabi--Yau backgrounds to open strings with framing.Comment: 49 pages, 3 eps figures; section added on non-perturbative proposal and 2d gravity; minor typos correcte

Climate Change and Geographic Ranges: The Implications for Russian Forests

Forest ecosystems of the Russian Federation are expected to face high risks under environmental dynamics related to climate change. Analyzing the likely impacts of climate change on forest ecosystems is crucial in order to understand the potential adaptation of forests, to guide management strategies, as well as to preserve ecosystem services. With the aim to provide information on the possible modifications of geographic ranges, in the medium to long-term, for some Russian dominant forest species under climate change, we applied a Cascade Ensemble System (CES) approach. This consists of combining Ensemble Platform for Species Distribution Models (SDMs) to six bias-corrected Earth System Model (ESM) projections, driven in turn by two Representative Concentration Pathways (RCPs) proxies of greenhouse gas emission scenarios, in order to obtain area maps of the future suitability for forest species. The suitability information is then flagged with information about its “likelihood,” adopting the IPCC terminology based on a consensus among projections. Maps of aggregated changes were created in order to identify areas potentially more vulnerable to climate change. Results showed that possible impacts of climate change (either gain or loss) were diversified across species with a pronounced Northward shift of the ranges. Further analyses were performed at sub-regional levels revealing the potential for the Arctic Circle to become a refuge area for some conifer species. Species-aggregated change analyses spotted two distinct areas as more vulnerable to habitat change, in the central and south-east portions of the Russian territory. Our findings represent useful and immediate biogeographical information available to Russian policy makers to delineate conservation strategies and forest management plans

Efectos biofísicos sobre la temperatura y la precipitación debido al cambio de cobertura terrestre

Anthropogenic land cover changes (LCC) affect regional and global climate through biophysical variations of the surface energy budget mediated by albedo, evapotranspiration, and roughness. This change in surface energy budget may exacerbate or counteract biogeochemical greenhouse gas effects of LCC, with a large body of emerging assessments being produced, sometimes apparently contradictory. We reviewed the existing scientific literature with the objective to provide an overview of the state-of-the-knowledge of the biophysical LCC climate effects, in support of the assessment of mitigation/adaptation land policies. Out of the published studies that were analyzed, 28 papers fulfilled the eligibility criteria, providing surface air temperature and/or precipitation change with respect to LCC regionally and/or globally. We provide a synthesis of the signal, magnitude and uncertainty of temperature and precipitation changes in response to LCC biophysical effects by climate region (boreal/temperate/tropical) and by key land cover transitions. Model results indicate that a modification of biophysical processes at the land surface has a strong regional climate effect, and non-negligible global impact on temperature. Simulation experiments of large-scale (i.e. complete) regional deforestation lead to a mean reduction in precipitation in all regions, while air surface temperature increases in the tropics and decreases in boreal regions. The net global climate effects of regional deforestation are less certain. There is an overall consensus in the model experiments that the average global biophysical climate response to complete global deforestation is atmospheric cooling and drying. Observed estimates of temperature change following deforestation indicate a smaller effect than model-based regional estimates in boreal regions, comparable results in the tropics, and contrasting results in temperate regions. Regional/local biophysical effects following LCC are important for local climate, water cycle, ecosystems, their productivity and biodiversity, and thus important to consider in the formulation of adaptation policy. However before considering the inclusion of biophysical climate effects of LCC under the UNFCCC, science has to provide robust tools and methods for estimation of both country and global level effects

Performance of the model for end-stage liver disease score for mortality prediction and the potential role of etiology

Background & Aims: Although the discriminative ability of the model for end-stage liver disease (MELD) score is generally considered acceptable, its calibration is still unclear. In a validation study, we assessed the discriminative performance and calibration of 3 versions of the model: original MELD-TIPS, used to predict survival after transjugular intrahepatic portosystemic shunt (TIPS); classic MELD-Mayo; and MELD-UNOS, used by the United Network for Organ Sharing (UNOS). We also explored recalibrating and updating the model. Methods: In total, 776 patients who underwent elective TIPS (TIPS cohort) and 445 unselected patients (non-TIPS cohort) were included. Three, 6 and 12-month mortality predictions were calculated by the 3 MELD versions: discrimination was assessed by c-statistics and calibration by comparing deciles of predicted and observed risks. Cox and Fine and Grey models were used for recalibration and prognostic analyses. Results: In the TIPS/non-TIPS cohorts, the etiology of liver disease was viral in 402/188, alcoholic in 185/130, and non-alcoholic steatohepatitis in 65/33; mean follow-up±SD was 25±9/19±21 months; and the number of deaths at 3-6-12 months was 57-102-142/31-47-99, respectively. C-statistics ranged from 0.66 to 0.72 in TIPS and 0.66 to 0.76 in non-TIPS cohorts across prediction times and scores. A post hoc analysis revealed worse c-statistics in non-viral cirrhosis with more pronounced and significant worsening in the non-TIPS cohort. Calibration was acceptable with MELD-TIPS but largely unsatisfactory with MELD-Mayo and -UNOS whose performance improved much after recalibration. A prognostic analysis showed that age, albumin, and TIPS indication might be used to update the MELD. Conclusions: In this validation study, the performance of the MELD score was largely unsatisfactory, particularly in non-viral cirrhosis. MELD recalibration and candidate variables for an update to the MELD score are proposed. Lay summary: While the discriminative performance of the model for end-stage liver disease (MELD) score is credited to be fair to good, its calibration, the correspondence of observed to predicted mortality, is still unsettled. We found that application of 3 different versions of the MELD in 2 independent cirrhosis cohorts yielded largely imprecise mortality predictions particularly in non-viral cirrhosis. Thus, we propose a recalibration and suggest candidate variables for an update to the model

Direct-acting antivirals and hepatocellular carcinoma in chronic hepatitis C: A few lights and many shadows

With the introduction of direct-acting antiviral agents (DAA), the rate of sustained virological response (SVR) in the treatment of hepatitis C virus (HCV) has radically improved to over 95%. Robust scientific evidence supports a beneficial role of SVR after interferon therapy in the progression of cirrhosis, resulting in a decreased incidence of hepatocellular carcinoma (HCC). However, a debate on the impact of DAAs on the development of HCC is ongoing. This review aimed to analyse the scientific literature regarding the risk of HCC in terms of its recurrence and occurrence after the use of DAAs to eradicate HCV infection. Among 11 studies examining HCC occurrence, the de novo incidence rate ranged from 0 to 7.4% (maximum follow-up: 18 mo). Among 18 studies regarding HCC recurrence, the rate ranged from 0 to 54.4% (maximum "not well-defined" followup: 32 mo). This review highlights the major difficulties in interpreting data and reconciling the results of the included studies. These difficulties include heterogeneous cohorts, potential misclassifications of HCC prior to DAA therapy, the absence of an adequate control group, short follow-up times and different kinds of follow-up. Moreover, no clinical feature-based scoring system accounts for the molecular characteristics and pathobiology of the tumours. Nonetheless, this review does not suggest that there is a higher rate of de novo HCC occurrence or recurrence after DAA therapy in patients with previous HCV infection. \ua9 2018 The Author(s). Published by Baishideng Publishing Group Inc. All rights reserved