511 research outputs found

    The Galvin property under the Ultrapower Axiom

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    We continue the study of the Galvin property. In particular, we deepen the connection between certain diamond-like principles and non-Galvin ultrafilters. We also show that any Dodd sound ultrafilter that is not a pp-point is non-Galvin. We use these ideas to formulate an essentially optimal large cardinal hypothesis that ensures the existence of a non-Galvin ultrafilter, improving on results of Benhamou and Dobrinen. Finally, we use a strengthening of the Ultrapower Axiom to prove that in all the known canonical inner models, a κ\kappa-complete ultrafilter on κ\kappa has the Galvin property if and only if it is an iterated sum of pp-points

    Hadronic interactions, precocious unification, and cosmic ray showers at Auger energies

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    At Auger energies only model predictions enable us to extract primary cosmic ray features. The simulation of the shower evolution depends sensitively on the first few interactions, necessarily related to the quality of our understanding of high energy hadronic collisions. Distortions of the standard ``soft semi-hard'' scenario include novel large compact dimensions and a string or quantum gravity scale not far above the electroweak scale. Na\"{\i}vely, the additional degrees of freedom yield unification of all forces in the TeV range. In this article we study the influence of such precocious unification during atmospheric cascade developments by analyzing the most relevant observables in proton induced showers.Comment: 16 pages latex. 4 eps figure

    Modeling the impact of glacial runoff on fjord circulation and submarine melt rate using a new subgrid-scale parameterization for glacial plumes

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    This work was funded by NERC grant NE/K014609/1 to Peter Nienow and Andrew Sole.The injection at depth of ice sheet runoff into fjords may be an important control on the frontal melt rate of tidewater glaciers. Here we develop a new parameterization for ice marginal plumes within the Massachusetts Institute of Technology General Circulation Model (MITgcm), allowing three-dimensional simulation of large (500 km2) glacial fjords on annual (or longer) time scales. We find that for an idealized fjord (without shelf-driven circulation), subglacial runoff produces a thin, strong, and warm down-fjord current in the upper part of the water column, balanced by a thick and slow up-fjord current at greater depth. Although submarine melt rates increase with runoff due to higher melt rates where the plume is in contact with the ice front, we find that annual submarine melt rate across the ice front is relatively insensitive to variability in annual runoff. Better knowledge of the spatial distribution of runoff, controls on melt rate in those areas not directly in contact with plumes, and feedback mechanisms linking submarine melting and iceberg calving are necessary to more fully understand the sensitivity of glacier mass balance to runoff-driven fjord circulation.Publisher PDFPeer reviewe

    Informant Personality Is Associated With Ratings of Memory Problems in Older Adults

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    Memory complaints are a key diagnostic criterion for dementia and Mild Cognitive Impairment. Rating scales can be used to capture information about individuals’ memory problems from informants such as family members. However, problems with scale reliability suggest that individual differences influence the ratings informants provide. This project tested whether informants’ neuroticism was associated with their ratings of an older adult’s memory. In an online study, 293 volunteers completed a Five Factor personality questionnaire and used two memory questionnaires to provide ratings of memory problems in an older individual they knew well. Rater neuroticism correlated positively with estimates of memory problems: more neurotic informants provided higher estimates of memory difficulties in the person they were rating. A second study replicated this finding with 786 volunteers and another widely used memory measure, the AD8. In both studies, exploratory analyses suggested the effect size was large enough to impact on clinical practice

    Novel metered aerosol valve

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    The design and performance of a new valving mechanism for portable pressurized spraying devices is described, where the propellant in the device is a safe gas (so-called compressed gas) propellant rather than the current liquefied gases all of which are either volatile organic compounds or greenhouse gases. The valve sprays a fixed volume of liquid when the spraying actuator is depressed, as is essential used medical sprays, such as pressurized metered dose inhalers and nasal sprays, and also for automatic (wall-mounted) aerosol delivery systems for air-fresheners, insecticides and disinfectants. For ‘compressed gas’ aerosol formats, there is no flash vaporization of propellant so that pumping liquid from a metering chamber and atomization to form a spray must be achieved entirely by designing some means of using the pumping action of the gas in the container to act upon the liquid in the metering chamber. The new design utilizes a loosely fitting spherical piston element and a simple arrangement of a concentric housing and a moveable valve stem, such that liquid flow paths between the different elements are automatically closed and opened in the correct time sequence when the valve stem is depressed and released. Spraying data show excellent repeatability of liquid sprayed per pulse throughout the lifetime of device and drop sizes that are acceptable for devices such as air-fresheners and nasal sprays. The valve has only one additional component compared with liquefied gas metered valves and can be straightforwardly injection moulded. As will be explained, previous attempts failed due to expense, complexity and unreliability. Keywords Aerosol valve, spray metering, insert, inhaler, air-freshene

    Next generation of consumer aerosol valve design using inert gases

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    The current global consumer aerosol products such as deodorants, hairsprays, air-fresheners, polish, insecticide, disinfectant are primarily utilised unfriendly environmental propellant of liquefied petroleum gas (LPG) for over three decades. The advantages of the new innovative technology described in this paper are: (i) no butane or other liquefied hydrocarbon gas; (ii) compressed air, nitrogen or other safe gas propellant; (iii) customer acceptable spray quality and consistency during can lifetime; (iv) conventional cans and filling technology. Volatile organic compounds and greenhouse gases must be avoided but there are no flashing propellants replacements that would provide the good atomisation and spray reach. On the basis of the energy source for atomising, the only feasible source is inert gas (i.e. compressed air), which improves atomisation by gas bubbles and turbulence inside the atomiser insert of the actuator. This research concentrates on using ‘bubbly flow’ in the valve stem, with injection of compressed gas into the passing flow, thus also generating turbulence. Using a vapour phase tap in conventional aerosol valves allows the propellant gas into the liquid flow upstream of the valve. However, forcing bubbly flow through a valve is not ideal. The novel valves designed here, using compressed gas, thus achieved the following objectives when the correct combination of gas and liquid inlets to the valve, and the type and size of atomiser ‘insert’ were derived: 1. Produced a consistent flow rate and drop size of spray throughout the life of the can, compatible with the current conventional aerosols that use LPG: a new ‘constancy’ parameter is defined and used to this end. 2. Obtained a discharge flow rate suited to the product to be sprayed; typically between 0.4 g/s and 2.5 g/s. 3. Attained the spray droplets size suited to the product to be sprayed; typically between 40 mm and 120 mm

    Prefrontal Cortex Modulation during Anticipation of Working Memory Demands as Revealed by Magnetoencephalography

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    During the anticipation of task demands frontal control is involved in the assembly of stimulus-response mappings based on current goals. It is not clear whether prefrontal modulations occur in higher-order cortical regions, likely reflecting cognitive anticipation processes. The goal of this paper was to investigate prefrontal modulation during anticipation of upcoming working memory demands as revealed by magnetoencephalography (MEG). Twenty healthy volunteers underwent MEG while they performed a variation of the Sternberg Working Memory (WM) task. Beta band (14–30 Hz) SAM (Synthetic Aperture Magnetometry) analysis was performed. During the preparatory periods there was an increase in beta power (event-related synchronization) in dorsolateral prefrontal cortex (DLPFC) bilaterally, left inferior prefrontal gyrus, left parietal, and temporal areas. Our results provide support for the hypothesis that, during preparatory states, the prefrontal cortex is important for biasing higher order brain regions that are going to be engaged in the upcoming task

    The true self online: personality correlates of preference for self-expression online, and observer ratings of personality online and offline

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    Theorists have suggested some people find it easier to express their “true selves” online than in person. Among 523 participants in an online study, Shyness was positively associated with online ‘Real Me’ self location, while Conscientiousness was negatively associated with an online self. Extraversion was indirectly negatively associated with an online self, mediated by Shyness. Neuroticism was positively associated with an online self, partly mediated by Shyness. 107 online and offline friends of participants provided ratings of them. Overall, both primary participants and their observers indicated that offline relationships were closer. However, participants who located their Real Me online reported feeling closer to their online friends than did those locating their real selves offline. To test whether personality is better expressed in online or offline interactions, observers’ ratings of participants’ personalities were compared. Both online and offline observers’ ratings of Extraversion, Agreeableness and Conscientiousness correlated with participants’ self-reports. However, only offline observers’ ratings of Neuroticism correlated with participants’ own. Except for Neuroticism, the similarity of online and offline observers’ personality ratings to participants’ self-reports did not differ significantly. The study provides no evidence that online self-presentations are more authentic; indeed Neuroticism may be more visibly expressed offline

    A Precise Cluster Mass Profile Averaged from the Highest-Quality Lensing Data

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    We outline our methods for obtaining high precision mass profiles, combining independent weak-lensing distortion, magnification, and strong-lensing measurements. For massive clusters the strong and weak lensing regimes contribute equal logarithmic coverage of the radial profile. The utility of high-quality data is limited by the cosmic noise from large scale structure along the line of sight. This noise is overcome when stacking clusters, as too are the effects of cluster asphericity and substructure, permitting a stringent test of theoretical models. We derive a mean radial mass profile of four similar mass clusters of high-quality HST and Subaru images, in the range R=40kpc/h to 2800kpc/h, where the inner radial boundary is sufficiently large to avoid smoothing from miscentering effects. The stacked mass profile is detected at 58-sigma significance over the entire radial range, with the contribution from the cosmic noise included. We show that the projected mass profile has a continuously steepening gradient out to beyond the virial radius, in remarkably good agreement with the standard Navarro-Frenk-White form predicted for the family of CDM-dominated halos in gravitational equilibrium. The central slope is constrained to lie in the range, -dln{\rho}/dln{r}=0.89^{+0.27}_{-0.39}. The mean concentration is c_{vir}=7.68^{+0.42}_{-0.40} (at a mean virial mass 1.54^{+0.11}_{-0.10}\times 10^{15} M_{sun}/h), which is high for relaxed, high-mass clusters, but consistent with LCDM when a sizable projection bias estimated from N-body simulations is considered. This possible tension will be more definitively explored with new cluster surveys, such as CLASH, LoCuSS, Subaru HSC, and XXM-XXL, to construct the c-M relation over a wider mass range.Comment: Accepted by ApJ, minor text changes (10 pages, 3 figures
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