518 research outputs found
The Galvin property under the Ultrapower Axiom
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 -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 -complete ultrafilter on has the Galvin property if and only
if it is an iterated sum of -points
Hadronic interactions, precocious unification, and cosmic ray showers at Auger energies
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
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
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
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
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
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
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
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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