Impact of extreme climatic events on wheat productivity in South-West, Western Australia

It is of major concern that climate change will be associated with an increase in extreme events, in recent years there are evidences of an increase in the frequency and intensity of such events. To confirm this, a trend analysis of historical extreme events was undertaken using case studies. We also examined likely impact of climate extremes on wheat production in the near future (2030). Extreme climate events were determined using Climate Extreme Indices (CEIs) adapted from the Expert Team on Climate Change Detection Indices (ETCCDI). Biophysical examination of wheat productivity was conducted through applying a Global Climate Model (GCM) data set projected for 1991-2010, downscaled by a quantile matching (QM), to APSIM and comparing the output with simulated historical production. Changes to the occurrence and intensity of extreme climatic events have occurred when evaluating the output data to the defined CEIs. An increase in extreme maximum temperatures, a decrease in minimum temperatures and an increase in rainfall variability have been observed in the last decade. Extreme event intensity is expected to decrease as frequency increases in South-West, Western Australia. Wheat yield at a relatively high rainfall site (Katanning, WA) projected to return higher yield compared to the baseline due to decreasing extreme event intensity projected for 2030 (RCP: 8.5, GCM: GFDL-CM3, downscaled by QM). However, the annual wheat yield trends for both simulations, historical and projected climate for 2030, are expected to decrease annually through time as a result of the changing intensity and frequency of extreme climatic events

The septin cytoskeleton facilitates membrane retraction during motility and blebbing.

Increasing evidence supports a critical role for the septin cytoskeleton at the plasma membrane during physiological processes including motility, formation of dendritic spines or cilia, and phagocytosis. We sought to determine how septins regulate the plasma membrane, focusing on this cytoskeletal element's role during effective amoeboid motility. Surprisingly, septins play a reactive rather than proactive role, as demonstrated during the response to increasing hydrostatic pressure and subsequent regulatory volume decrease. In these settings, septins were required for rapid cortical contraction, and SEPT6-GFP was recruited into filaments and circular patches during global cortical contraction and also specifically during actin filament depletion. Recruitment of septins was also evident during excessive blebbing initiated by blocking membrane trafficking with a dynamin inhibitor, providing further evidence that septins are recruited to facilitate retraction of membranes during dynamic shape change. This function of septins in assembling on an unstable cortex and retracting aberrantly protruding membranes explains the excessive blebbing and protrusion observed in septin-deficient T cells

Host Plant Resistance of Cool-Season (C3) Turfgrasses to Above- and Belowground Feeding by Tipula paludosa (Diptera: Tipulidae)

Feeding on above- and belowground plant tissues by Tipula paludosa Meigen during the period of rapid growth from second to forth instars is highly damaging to cool-season (C3) turfgrasses. It may be possible to reduce this damage by identifying grass genotypes that increase host plant protection. This study examined the impacts of plant genotype, endophyte infection, and plant ontogeny on host plant and insect responses during whole-plant feeding by T. paludosa. A series of no-choice greenhouse trials were conducted with third instar crane flies to determine 1) host plant tolerance in terms of reductions to above- and belowground plant biomass, 2) antixenosis resistance impacting insect behavior (emigration), and 3) antibiosis resistance impacting insect growth. Results showed that insect infestation level was the primary factor influencing plant biomass reductions. Belowground tissues were more tolerant to feeding than were aboveground tissues, with tall fescues, Festuca arundinacea Schreber, being most resistant to aboveground biomass reduction. Host plant associations with intercellular fungal endophytes (E+) decreased insect weight gain and decreased insect movement, but did not increase host plant tolerance. Plant ontogeny affected this response with insect weight gain significantly decreased on young (28 d) growth E+ grasses but not on old (90 d) growth E+ grasses, however. Host plant genotype and plant ontogeny can have significant impacts to host plant tolerance and insect physiology for T. paludosa larva. Furthermore, plant-endophyte associations have apparent sublethal effects that impact insect fitness and may further enhance host plant protectio

Temperature contributes to host specialization of coffee wilt disease (Fusarium xylarioides) on arabica and robusta coffee crops

Coffee wilt disease, caused by the fungus Fusarium xylarioides, is a vascular wilt disease that has affected coffee production in sub-Saharan Africa over the past century. Today, the disease has two host-specific populations specialising on arabica and robusta coffee crops, which grow at high and low altitude, respectively. Here we test whether adaptation to different temperatures contributes to specialisation of the fungi on each crop. Firstly, climate models show that the severity of the arabica and robusta populations of coffee wilt disease correlates with temperature. The robusta population shows higher peak severity than the arabica population overall, but the latter has greater cold tolerance. Secondly, growth assays of thermal performance of fungal strains in vitro show that, while robusta strains grow faster than arabicas at intermediate temperatures, the arabica strains have higher sporulation and spore germination rates at temperatures below 15ºC. The match between environmental patterns of severity in nature with thermal performance of fungal cultures in the laboratory supports a role for temperature adaptation in specialisation on arabica and robusta coffee. Extrapolating our temperature-models to future climate change predicts that disease severity could decline on average due to increased temperature but could increase in some coffee-growing regions

Costly Information Acquisition

We examine price formation in a simple static model with asymmetric information, a countable number of risk neutral traders and without noise traders. Prices can exhibit excess volatility (the variance of prices exceeds the variance of dividends), even in such a simple model. More generally, we show that for an open set of parameter values no equilibrium has prices which turn out to equal the value of dividends state by state, while for another open set of parameter values there exist equilibria such that equilibrium prices equal the value of dividends state by state. When information collection is endogenous and costly, expected prices exhibit a "V-shape" as a function of the cost of information: They are maximized when information is either costless so that everyone acquires it, or else is so costly that no one chooses to acquire it. Prices are depressed if information is cheap enough so that some agents become informed, while others do not. If the model is altered so that information is useful in making productive decisions, then the V-shape is altered, reducing the attractiveness of prohibitively high costs.

Influence of Riding Experience on Glance Behavior, Brake Response Time and Deceleration Rates by Drivers and Motorcyclists

The focus of the research was to address the crash avoidance behaviors of drivers versus motorcyclists. Avoidance tasks include, attention maintenance and hazard anticipation measured with glance behaviors, and hazard mitigation measured with response times and deceleration. Specifically, where might the driver behavior be similar or different than that of a motorcyclist? The performances of 23participants were analyzed while they drove a car and rode a motorcycle over the same low-volume, open roads. Participants wore eye-tracking equipment used to record eye-glance information while the motorcycle and car were instrumented with an on-board accelerometer and GPS apparatus. Operators also responded by braking quickly to a stop when an LED, mounted in front of them, was illuminated. Motorcyclists spent less time glancing toward the road ahead and made fewer last-glances toward the direction of most threatening traffic before turning when riding the motorcycle, as opposed to when driving a car. Additionally, motorcyclists’ response times were similar to those when driving, yet motorcyclists decelerated less sharply compared to drivers. These results suggest that riders may be exposing themselves to unnecessary risk. Specifically, motorcyclists frequently failed to make proper glances and practice optimal riding techniques. The implication of these results relative to a training curriculum is discussed

Endogenous games and mechanisms: Side payments among players

We characterize the outcomes of games when players may make binding offers of strategy contingent side payments before the game is played. This does not always lead to efficient outcomes, despite complete information and costless contracting. The characterizations are illustrated in a series of examples, including voluntary contribution public good games, Cournot and Bertrand oligopoly, principal–agent problems, and commons games, among others

Molecular evolution: sex accelerates adaptation

An analysis confirms the long-standing theory that sex increases the rate of adaptive evolution by accelerating the speed at which beneficial mutations sweep through sexual, as opposed to asexual, populations

Can Physicians Identify Inappropriate Nuclear Stress Tests? An Examination of Inter-Rater Reliability for the 2009 Appropriate Use Criteria for Radionuclide Imaging

Background—We sought to determine inter-rater reliability of the 2009 Appropriate Use Criteria for radionuclide imaging and whether physicians at various levels of training can effectively identify nuclear stress tests with inappropriate indications. Methods and Results—Four hundred patients were randomly selected from a consecutive cohort of patients undergoing nuclear stress testing at an academic medical center. Raters with different levels of training (including cardiology attending physicians, cardiology fellows, internal medicine hospitalists, and internal medicine interns) classified individual nuclear stress tests using the 2009 Appropriate Use Criteria. Consensus classification by 2 cardiologists was considered the operational gold standard, and sensitivity and specificity of individual raters for identifying inappropriate tests were calculated. Inter-rater reliability of the Appropriate Use Criteria was assessed using Cohen κ statistics for pairs of different raters. The mean age of patients was 61.5 years; 214 (54%) were female. The cardiologists rated 256 (64%) of 400 nuclear stress tests as appropriate, 68 (18%) as uncertain, 55 (14%) as inappropriate; 21 (5%) tests were unable to be classified. Inter-rater reliability for noncardiologist raters was modest (unweighted Cohen κ, 0.51, 95% confidence interval, 0.45–0.55). Sensitivity of individual raters for identifying inappropriate tests ranged from 47% to 82%, while specificity ranged from 85% to 97%. Conclusions—Inter-rater reliability for the 2009 Appropriate Use Criteria for radionuclide imaging is modest, and there is considerable variation in the ability of raters at different levels of training to identify inappropriate tests