Killing and replacing queen-laid eggs: low cost of worker policing in the honey bee

Worker honeybees, Apis mellifera, police each other’s reproduction by killing worker-laid eggs. Previous experiments demonstrated that worker policing is effective, killing most (∼98%) worker-laid eggs. However, many queen-laid eggs were also killed (∼50%) suggesting that effective policing may have high costs. In these previous experiments, eggs were transferred using forceps into test cells, mostly into unrelated discriminator colonies. We measured both the survival of unmanipulated queen-laid eggs and the proportion of removal errors that were rectified by the queen laying a new egg. Across 2 days of the 3-day egg stage, only 9.6% of the queen-laid eggs in drone cells and 4.1% in worker cells were removed in error. When queen-laid eggs were removed from cells, 85% from drone cells and 61% from worker cells were replaced within 3 days. Worker policing in the honeybee has a high benefit to policing workers because workers are more related to the queen’s sons (brothers, r = 0.25) than sister workers’ sons (0.15). This study shows that worker policing also has a low cost in terms of the killing of queen-laid eggs, as only a small proportion of queen-laid eggs are killed, most of which are rapidly replaced

Analysis of DCE-MRI Data using a Nonnegative Elastic Net

We present a nonnegative Elastic Net approach for the analysis of Dynamic Contrast-Enhanced Magnetic Resonance Imaging data. A multi-compartment approach is considered, which is translated into a (restricted) least square model selection problem. This is done by using a set of basis functions for a given set of candidate rate constants. The form of the basis functions is derived from a kinetic model and thus describes the contribution of some compartment. Using the Elastic Net estimator, we chose clusters of basis functions, and hence, rate constants of compartments. As further challenge, the estimator has to be restricted to positive regression parameters, which correspond to transfer rates of the compartments. The proposed estimation method is applied to an in-vivo data set

Influence of Exhaust Hydrogen addition and the Effects of oxygenated Fuels on a three-way Catalyst for GDI Engines

To mitigate the detrimental effects of ever increasing consumption of fossil fuels by the transport sector on urban air quality and the global climate, despite the continuous tightening of emissions legislation for road transport, necessitates further development of exhaust after-treatment systems and renewable fuels. To this end, it is vital that strategies for enhancing low temperature efficiencies of after-treatment catalysts be developed and that they can operate in synergy with the combustion of oxygenated renewable fuel blends. One such strategy is the upstream injection of hydrogen (H₂), which has shown to be effective in a lean exhaust environment but has received little attention in the context of stoichiometric GDI engine exhaust. The experimental studies in this work were carried out on a modified spark-ignition engine, equipped with hydrogen introduction and variable emission extraction capabilities to investigate commercially available after-treatment devices in a real exhaust gas environment. The system was built and commissioned for a precise H₂ addition upstream of a three-way catalyst (TWC), as well as long and short duration experiments for varying fuel blends, so as to investigate the effect of H₂ addition (H₂ levels up to 8000 ppm) and various oxygenated drop-in blends on the conversion performance of different TWC’s. Small amounts of H₂ addition showed a reduction in light-off temperature for the legislated gaseous emission species and increasing H₂ addition levels resulted in a decrease in steady-state oxidation conversion rates. H₂ was also found to decrease the time for particulate levels to reach stable conditions downstream of the TWC. A reduced light-off temperature was found with shorter oxygenated drop-in molecules, an effect which decreased with increasing chain length or complexity of the drop-in molecule. Any fuel effect on tailpipe particulate levels was inferior to the capability of the TWC to oxidise and trap small sized particles

The roles of dynamical variability and aerosols in cirrus cloud formation

International audienceThe probability of occurrence of ice crystal number densities in young cirrus clouds is examined based on airborne measurements. The observations have been carried out at midlatitudes in both hemispheres at equivalent latitudes (~52?55° N/S) during the same season (local autumn in 2000). The in situ measurements considered in the present study include temperatures, vertical velocities, and ice crystal concentrations, the latter determined with high precision and accuracy using a counterflow virtual impactor. Most young cirrus clouds typically contain high number densities (1?10 cm?3) of small (diameter -1. A second mode containing larger crystals extends from ~1 cm?3 to low concentrations close to the detection threshold (~3×104cm?3) and is associated with lower updraft speeds. Results of a statistical analysis provide compelling evidence that the dynamical variability of vertical air motions on the mesoscale is the key factor determining the observed probability distributions of pristine ice crystal concentrations in cirrus. Other factors considered are variations of temperature as well as size, number, and ice nucleation thresholds of the freezing aerosol particles. The variability in vertical velocities is likely caused by atmospheric waves. Inasmuch as gravity waves are widespread, mesoscale variability in vertical velocities can be viewed as a universa feature of young cirrus clouds. Large-scale models that do not account for this subgrid-scale variability yield erroneous predictions of the variability of basic cirrus cloud properties. Climate change may bring about changes in the global distribution of updraft speeds, mean air temperatures, and aerosol properties. As shown in this work, these changes could significantly modify the probability distribution of cirrus ice crystal concentrations. This study emphasizes the key role of vertical velocities and mesoscale variability in vertical velocities in controlling cirrus properties. The results suggest that, in any effort to ascribe cause to trends of cirrus cloud properties, a careful evaluation of dynamical changes in cloud formation should be done before conclusions regarding the role of other anthropogenic factors, such as changes in aerosol composition, are made

Global radiative forcing from contrail cirrus

Aviation makes a significant contribution to anthropogenic climate forcing. The impacts arise from emissions of greenhouse gases, aerosols and nitrogen oxides, and from changes in cloudiness in the upper troposphere. An important but poorly understood component of this forcing is caused by âÂÂcontrail cirrusâÂÂâÂÂa type of cloud that consist of young line-shaped contrails and the older irregularly shaped contrails that arise from them. Here we use a global climate model that captures the whole life cycle of these man-made clouds to simulate their global coverage, as well as the changes in natural cloudiness that they induce. We show that the radiative forcing associated with contrail cirrus as a whole is about nine times larger than that from line-shaped contrails alone. We also find that contrail cirrus cause a significant decrease in natural cloudiness, which partly offsets their warming effect. Nevertheless, net radiative forcing due to contrail cirrus remains the largest single radiative-forcing component associated with aviation. Our findings regarding global radiative forcing by contrail cirrus will allow their effects to be included in studies assessing the impacts of aviation on climate and appropriate mitigation options

The influence of the Tübingen soft palate plate and early cleft closure on the nasopharyngeal airway for the management of airway obstruction in an infant with Pierre Robin sequence: A case report

AbstractINTRODUCTIONA Tübingen palate plate and early cleft closure for successful airway management is described in a newborn with Pierre Robin sequence.PRESENTATION OF CASEA three-day-old newborn with an acute airway obstruction underwent primary treatment with a Tübingen soft palate plate.DISCUSSIONAfter stabilization of the airway, the cleft soft palate was closed after three months.CONCLUSIONThe Tübingen soft palate plate proved to be a very satisfactory treatment for the infant

Dust ice nuclei effects on cirrus clouds

In order to study aerosol–cloud interactions in cirrus clouds, we apply a new multiple-mode ice microphysical scheme to the general circulation model ECHAM5-HAM. The multiple-mode ice microphysical scheme allows for analysis of the competition between homogeneous freezing of solution droplets, deposition nucleation of pure dust particles, and immersion freezing of coated dust particles and pre-existing ice. We base the freezing efficiencies of coated and pure dust particles on the most recent laboratory data. The effect of pre-existing ice, which has been neglected in previous ice nucleation parameterizations, is to deplete water vapour by depositional growth and thus prevent homogeneous and heterogeneous freezing from occurring

Factors controlling contrail cirrus optical depth

Aircraft contrails develop into contrail cirrus by depositional growth and sedimentation of ice particles and horizontal spreading due to wind shear. Factors controlling this development include temperature, ice supersaturation, thickness of ice-supersaturated layers, and vertical gradients in the horizontal wind field. An analytical microphysical cloud model is presented and validated that captures these processes. Many individual contrail cirrus are simulated that develop differently owing to the variability in the controlling factors, resulting in large samples of cloud properties that are statistically analyzed. Contrail cirrus development is studied over the first four hours past formation, similar to the ages of line-shaped contrails that were tracked in satellite imagery on regional scales. On these time scales, contrail cirrus optical depth and microphysical variables exhibit a marked variability, expressed in terms of broad and skewed probability distribution functions. Simulated mean optical depths at a wavelength of 0.55 <i>μ</i>m range from 0.05-0.5 and a substantial fraction 20-50% of contrail cirrus stay subvisible (optical depth <0.02), depending on meteorological conditions. <br><br> A detailed analysis based on an observational case study over the continental USA suggests that previous satellite measurements of line-shaped persistent contrails have missed about 89%, 50%, and 11% of contrails with optical depths 0-0.05, 0.05-0.1, and 0.1-0.2, respectively, amounting to 65% of contrail coverage of all optical depths. When comparing observations with simulations and when estimating the contrail cirrus climate impact, not only mean values but also the variability in optical depth and microphysical properties need to be considered