The secret world of shrimps: polarisation vision at its best

Animal vision spans a great range of complexity, with systems evolving to detect variations in optical intensity, distribution, colour, and polarisation. Polarisation vision systems studied to date detect one to four channels of linear polarisation, combining them in opponent pairs to provide intensity-independent operation. Circular polarisation vision has never been seen, and is widely believed to play no part in animal vision. Polarisation is fully measured via Stokes' parameters--obtained by combined linear and circular polarisation measurements. Optimal polarisation vision is the ability to see Stokes' parameters: here we show that the crustacean \emph{Gonodactylus smithii} measures the exact components required. This vision provides optimal contrast-enhancement, and precise determination of polarisation with no confusion-states or neutral-points--significant advantages. We emphasise that linear and circular polarisation vision are not different modalities--both are necessary for optimal polarisation vision, regardless of the presence of strongly linear or circularly polarised features in the animal's environment.Comment: 10 pages, 6 figures, 2 table

Endothelin-1 Predicts Hemodynamically Assessed Pulmonary Arterial Hypertension in HIV Infection.

BackgroundHIV infection is an independent risk factor for PAH, but the underlying pathogenesis remains unclear. ET-1 is a robust vasoconstrictor and key mediator of pulmonary vascular homeostasis. Higher levels of ET-1 predict disease severity and mortality in other forms of PAH, and endothelin receptor antagonists are central to treatment, including in HIV-associated PAH. The direct relationship between ET-1 and PAH in HIV-infected individuals is not well described.MethodsWe measured ET-1 and estimated pulmonary artery systolic pressure (PASP) with transthoracic echocardiography (TTE) in 106 HIV-infected individuals. Participants with a PASP ≥ 30 mmHg (n = 65) underwent right heart catheterization (RHC) to definitively diagnose PAH. We conducted multivariable analysis to identify factors associated with PAH.ResultsAmong 106 HIV-infected participants, 80% were male, the median age was 52 years and 77% were on antiretroviral therapy. ET-1 was significantly associated with higher values of PASP [14% per 0.1 pg/mL increase in ET-1, p = 0.05] and PASP ≥ 30 mmHg [PR (prevalence ratio) = 1.24, p = 0.012] on TTE after multivariable adjustment for PAH risk factors. Similarly, among the 65 individuals who underwent RHC, ET-1 was significantly associated with higher values of mean pulmonary artery pressure and PAH (34%, p = 0.003 and PR = 2.43, p = 0.032, respectively) in the multivariable analyses.ConclusionsHigher levels of ET-1 are independently associated with HIV-associated PAH as hemodynamically assessed by RHC. Our findings suggest that excessive ET-1 production in the setting of HIV infection impairs pulmonary endothelial function and contributes to the development of PAH

Fungal Adenylyl Cyclase Acts As a Signal Sensor and Integrator and Plays a Central Role in Interaction with Bacteria

10.1371/journal.ppat.1003612PLoS Pathogens910

A Dynamic Model of Interactions of Ca^(2+), Calmodulin, and Catalytic Subunits of Ca^(2+)/Calmodulin-Dependent Protein Kinase II

During the acquisition of memories, influx of Ca^(2+) into the postsynaptic spine through the pores of activated N-methyl-D-aspartate-type glutamate receptors triggers processes that change the strength of excitatory synapses. The pattern of Ca^(2+) influx during the first few seconds of activity is interpreted within the Ca^(2+)-dependent signaling network such that synaptic strength is eventually either potentiated or depressed. Many of the critical signaling enzymes that control synaptic plasticity, including Ca^(2+)/calmodulin-dependent protein kinase II (CaMKII), are regulated by calmodulin, a small protein that can bind up to 4 Ca^(2+) ions. As a first step toward clarifying how the Ca^(2+)-signaling network decides between potentiation or depression, we have created a kinetic model of the interactions of Ca^(2+), calmodulin, and CaMKII that represents our best understanding of the dynamics of these interactions under conditions that resemble those in a postsynaptic spine. We constrained parameters of the model from data in the literature, or from our own measurements, and then predicted time courses of activation and autophosphorylation of CaMKII under a variety of conditions. Simulations showed that species of calmodulin with fewer than four bound Ca^(2+) play a significant role in activation of CaMKII in the physiological regime, supporting the notion that processing ofCa^(2+) signals in a spine involves competition among target enzymes for binding to unsaturated species of CaM in an environment in which the concentration of Ca^(2+) is fluctuating rapidly. Indeed, we showed that dependence of activation on the frequency of Ca^(2+) transients arises from the kinetics of interaction of fluctuating Ca^(2+) with calmodulin/CaMKII complexes. We used parameter sensitivity analysis to identify which parameters will be most beneficial to measure more carefully to improve the accuracy of predictions. This model provides a quantitative base from which to build more complex dynamic models of postsynaptic signal transduction during learning

Reaching back: the relative strength of the retroactive emotional attentional blink

Visual stimuli with emotional content appearing in close temporal proximity either before or after a target a stimulus can hinder conscious perceptual processing of the target via an emotional attentional blink (EAB). This occurs for targets that appear after the emotional stimulus (forward EAB) and for those appearing before the emotional stimulus (retroactive EAB). Additionally, the traditional attentional blink (AB) occurs because detection of any target hinders detection of a subsequent target. The present study investigated the relations between these different attentional processes. Rapid sequences of landscape images were presented to thirty-one male participants with occasional landscape targets (rotated images). For the forward EAB, emotional or neutral distractor images of people were presented before the target; for the retroactive EAB, such images were also targets and presented after the landscape target. In the latter case, this design allowed investigation of the AB as well. Erotic and gory images caused more EABs than neutral images, but there were no differential effects on the AB. This pattern is striking because while using different target categories (rotated landscapes, people) appears to have eliminated the AB, the retroactive EAB still occurred, offering additional evidence for the power of emotional stimuli over conscious attention

Diagnostic value of harmonic transthoracic echocardiography in native valve infective endocarditis: comparison with transesophageal echocardiography

<p>Abstract</p> <p>Background</p> <p>Although echocardiography has been incorporated into the diagnostic algorithm of patients with suspected infective endocarditis (IE), systematic usage in clinical practice remains ill defined. To determine the diagnostic accuracy of detecting vegetations using harmonic transthoracic echocardiography (hTTE) as compared to transesophageal echocardiography (TEE) in patients with an intermediate likelihood of native valve IE.</p> <p>Methods</p> <p>Between 2004 and 2005, 36 consecutive inpatients with an intermediate likelihood of disease were prospectively evaluated by hTTE and TEE.</p> <p>Results</p> <p>Of 36 patients (21 males with a mean age of 57 ± 15 years, range 32 to 86 years), 19 patients had definite IE by TEE. The sensitivity for the detection of vegetations by hTTE was 84%, specificity of 88%, positive predictive value (PPV) of 89% and negative predictive value (NPV) of 82%. The association between hTTE and TTE interpretation for the presence and absence of vegetations were high (kappa = 0.90 and 0.85 respectively).</p> <p>Conclusion</p> <p>In patients with an intermediate likelihood of native valve IE, TTE with harmonic imaging provides diagnostic quality images in the majority of cases, has excellent concordance with TEE and should be recommended as the first line test.</p

Aviation turbulence: dynamics, forecasting, and response to climate change

Atmospheric turbulence is a major hazard in the aviation industry and can cause injuries to passengers and crew. Understanding the physical and dynamical generation mechanisms of turbulence aids with the development of new forecasting algorithms and, therefore, reduces the impact that it has on the aviation industry. The scope of this paper is to review the dynamics of aviation turbulence, its response to climate change, and current forecasting methods at the cruising altitude of aircraft. Aviation-affecting turbulence comes from three main sources: vertical wind shear instabilities, convection, and mountain waves. Understanding these features helps researchers to develop better turbulence diagnostics. Recent research suggests that turbulence will increase in frequency and strength with climate change, and therefore, turbulence forecasting may become more important in the future. The current methods of forecasting are unable to predict every turbulence event, and research is ongoing to find the best solution to this problem by combining turbulence predictors and using ensemble forecasts to increase skill. The skill of operational turbulence forecasts has increased steadily over recent decades, mirroring improvements in our understanding. However, more work is needed—ideally in collaboration with the aviation industry—to improve observations and increase forecast skill, to help maintain and enhance aviation safety standards in the future

Angel investor's selection criteria: a comparative institutional perspective

Despite the important role of angel investors as critical financial providers for new ventures, little is known regarding how institutions make their investment decisions. While angels make decisions based on selection criteria during the first stage, they are also embedded within and affected by different institutional settings and as a result weight these criteria differently than other investors. We compare angel investors' selection criteria in China and Denmark using the comparative institutional perspective. We use a policy capturing approach and hierarchy linear modeling, revealing that since Chinese angels are embedded within relationship-based institutional settings they tend to reply more on strong ties such as family and friends in management team, as well as weighting risks less compared to Danish angels operating within more rule-based institutional contexts

Measurement of Exclusive B Decays to Final States Containing a Charmed Baryon

Using data collected by the CLEO detector in the Upsilon(4S) region, we report new measurements of the exclusive decays of B mesons into final states of the type Lambda_c^+ p-bar n(pi), where n=0,1,2,3. We find signals in modes with one, two and three pions and an upper limit for the two body decay Lambda_c^+ pbar. We also make the first measurements of exclusive decays of B mesons to Sigma_c p-bar n(pi), where n=0,1,2. We find signals in modes with one and two pions and an upper limit for the two body decay Sigma_c p-bar. Measurements of these modes shed light on the mechanisms involved in B decays to baryons.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

Measurement of the Masses and Widths of the Sigma_c^++ and Sigma_c^0 Charmed Baryons

Using data recorded by the CLEO II and CLEO II.V detector configurations at CESR, we report new measurements of the masses of the Sigma_c^{++} and Sigma_c^0 charmed baryons, and the first measurements of their intrinsic widths. We find M(Sigma_c^{++}) - M(Lambda_c^+) = 167.4 +- 0.1 +- 0.2 MeV, Gamma(Sigma_c^{++}) = 2.3 +- 0.2 +- 0.3 MeV, and M(Sigma_c^0) - M(Lambda_c^+) = 167.2 +- 0.1 +- 0.2 MeV, Gamma(Sigma_c^0) = 2.5 +- 0.2 +- 0.3 MeV, where the uncertainties are statistical and systematic, respectively.Comment: 9 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PRD, Rapid Communications. Reference [13] correcte