182 research outputs found
Physical Investigation of the Potentially Hazardous Asteroid (144898) 2004 VD17
In this paper we present the observational campaign carried out at ESO NTT
and VLT in April and May 2006 to investigate the nature and the structure of
the Near Earth Object (144898) 2004 VD17. In spite of a great quantity of
dynamical information, according to which it will have a close approach with
the Earth in the next century, the physical properties of this asteroid are
largely unknown. We performed visible and near--infrared photometry and
spectroscopy, as well as polarimetric observations. Polarimetric and
spectroscopic data allowed us to classify 2004 VD17 as an E-type asteroid. A
good agreement was also found with the spectrum of the aubrite meteorite Mayo
Belwa. On the basis of the polarimetric albedo (p_v=0.45) and of photometric
data, we estimated a diameter of about 320 m and a rotational period of about 2
hours. The analysis of the results obtained by our complete survey have shown
that (144898) 2004 VD17 is a peculiar NEO, since it is close to the breakup
limits for fast rotator asteroids, as defined by Pravec and Harris (2000).
These results suggest that a more robust structure must be expected, as a
fractured monolith or a rubble pile in a "strength regime" (Holsapple 2002).Comment: 32 pages, 7 figure, paper accepted for publication in Icaru
Dynamic facial expressions of emotion transmit an evolving hierarchy of signals over time
Designed by biological and social evolutionary pressures, facial expressions of emotion comprise specific facial movements to support a near-optimal system of signaling and decoding. Although highly dynamical, little is known about the form and function of facial expression temporal dynamics. Do facial expressions transmit diagnostic signals simultaneously to optimize categorization of the six classic emotions, or sequentially to support a more complex communication system of successive categorizations over time? Our data support the latter. Using a combination of perceptual expectation modeling, information theory, and Bayesian classifiers, we show that dynamic facial expressions of emotion transmit an evolving hierarchy of âbiologically basic to socially specificâ information over time. Early in the signaling dynamics, facial expressions systematically transmit few, biologically rooted face signals supporting the categorization of fewer elementary categories (e.g., approach/avoidance). Later transmissions comprise more complex signals that support categorization of a larger number of socially specific categories (i.e., the six classic emotions). Here, we show that dynamic facial expressions of emotion provide a sophisticated signaling system, questioning the widely accepted notion that emotion communication is comprised of six basic (i.e., psychologically irreducible) categories, and instead suggesting four
Experimental Observation of Differences in the Dynamic Response of Newtonian and Viscoelastic Fluids
In this paper we present an experimental study of the dynamic responses of a
Newtonian fluid and a Maxwellian fluid under an oscillating pressure gradient.
We use laser Doppler anemometry in order to determine the velocity of each
fluid inside a cylindrical tube. In the case of the Newtonian fluid, the
dissipative nature is observed and the response obeys the Zhou and Sheng
universality (PRB 39, 12027 (1989)). In the dynamic response of the Maxwellian
fluid an enhancement at the frequencies predicted by the corresponding theory
(PRE 58, 6323 (1998)) is observed.Comment: 5 pages, 4 Figures, paper to be published in Phys. Rev.
Antihydrogen formation dynamics in a multipolar neutral anti-atom trap
Antihydrogen production in a neutral atom trap formed by an octupole-based
magnetic field minimum is demonstrated using field-ionization of weakly bound
anti-atoms. Using our unique annihilation imaging detector, we correlate
antihydrogen detection by imaging and by field-ionization for the first time.
We further establish how field-ionization causes radial redistribution of the
antiprotons during antihydrogen formation and use this effect for the first
simultaneous measurements of strongly and weakly bound antihydrogen atoms.
Distinguishing between these provides critical information needed in the
process of optimizing for trappable antihydrogen. These observations are of
crucial importance to the ultimate goal of performing CPT tests involving
antihydrogen, which likely depends upon trapping the anti-atom
Search For Trapped Antihydrogen
We present the results of an experiment to search for trapped antihydrogen
atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator.
Sensitive diagnostics of the temperatures, sizes, and densities of the trapped
antiproton and positron plasmas have been developed, which in turn permitted
development of techniques to precisely and reproducibly control the initial
experimental parameters. The use of a position-sensitive annihilation vertex
detector, together with the capability of controllably quenching the
superconducting magnetic minimum trap, enabled us to carry out a
high-sensitivity and low-background search for trapped synthesised antihydrogen
atoms. We aim to identify the annihilations of antihydrogen atoms held for at
least 130 ms in the trap before being released over ~30 ms. After a three-week
experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9
positrons to produce 6 10^5 antihydrogen atoms, we have identified six
antiproton annihilation events that are consistent with the release of trapped
antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts,
is incompatible with this observation at a significance of 5.6 sigma. Extensive
simulations predict that an alternative source of annihilations, the escape of
mirror-trapped antiprotons, is highly unlikely, though this possibility has not
yet been ruled out experimentally.Comment: 12 pages, 7 figure
Electronic cigarettes: A position statement from the Thoracic Society of Australia and New Zealand*
The TSANZ develops position statements where insufficient data exist to write formal clinical guidelines. In 2018, the TSANZ addressed the question of potential benefits and health impacts of electronic cigarettes (EC). The working party included groups focused on health impacts, smoking cessation, youth issues and priority populations. The 2018 report on the Public Health Consequences of E-Cigarettes from the United States NASEM was accepted as reflective of evidence to mid-2017. A search for papers subsequently published in peer-reviewed journals was conducted in August 2018. A small number of robust and important papers published until March 2019 were also identified and included. Groups identified studies that extended, modified or contradicted the NASEM report. A total of 3793 papers were identified and reviewed, with summaries and draft position statements developed and presented to TSANZ membership in April 2019. After feedback from members and external reviewers, a collection of position statements was finalized in December 2019. EC have adverse lung effects and harmful effects of long-term use are unknown. EC are unsuitable consumer products for recreational use, part-substitution for smoking or long-term exclusive use by former smokers. Smokers who require support to quit smoking should be directed towards approved medication in conjunction with behavioural support as having the strongest evidence for efficacy and safety. No specific EC product can be recommended as effective and safe for smoking cessation. Smoking cessation claims in relation to EC should be assessed by established regulators
Triaxial Superdeformation in 163 Lu
Abstract High-spin states in 163 Lu have been investigated using the Euroball spectrometer array. The previously known superdeformed band has been extended at low and high energies, and its connection to the normal-deformed states has been established. From its decay the mixing amplitude and interaction strength between superdeformed and normal states are derived. In addition, a new band with a similar dynamic moment of inertia has been found. The experimental results are compared to cranking calculations which suggest that the superdeformed bands in this mass region correspond to shapes with a pronounced triaxiality ( Îł â±20°)
Study Design and Baseline Characteristics of the CARDINAL Trial: A Phase 3 Study of Bardoxolone Methyl in Patients with Alport Syndrome
Introduction: Alport syndrome is a rare genetic disorder that affects as many as 60,000 persons in the USA and a total of 103,000 persons (200 pg/mL at baseline or with significant cardiovascular histories were excluded. Patients were randomized 1:1 to bardoxolone methyl or placebo, with stratification by baseline UACR. Results: A total of 371 patients were screened, and 157 patients were randomly assigned to receive bardoxolone methyl (n = 77) or placebo (n = 80). The average age at screening was 39.2 years, and 23 (15%) were <18 years of age. Of the randomized population, 146 (93%) had confirmed genetic diagnosis of Alport syndrome, and 62% of patients had X-linked mode of inheritance. Mean baseline eGFR was 62.7 mL/min/1.73 m2, and the geometric mean UACR was 141.0 mg/g. The average annual rate of eGFR decline prior to enrollment in the study was -4.9 mL/min/1.73 m2 despite 78% of the patient population receiving ACE inhibitor (ACEi) or ARB therapy. Discussion/Conclusion: CARDINAL is one of the largest interventional, randomized controlled trials in Alport syndrome conducted to date. Despite the use of ACEi or ARB, patients were experiencing significant loss of kidney function prior to study entry
Marking as judgment
An aspect of assessment which has received little attention compared with perennial concerns, such as standards or reliability, is the role of judgment in marking. This paper explores marking as an act of judgment, paying particular attention to the nature of judgment and the processes involved. It brings together studies which have explored marking from a psychological perspective for the purpose of critical discussion of the light they shed on each other and on the practice of marking. Later stages speculate on recent developments in psychology and neuroscience which may cast further light on educational assessment
The role of fundamental solution in Potential and Regularity Theory for subelliptic PDE
In this survey we consider a general Hormander type operator, represented as a sum of squares of vector fields plus a drift and we outline the central role of the fundamental solution in developing Potential and Regularity Theory for solutions of related PDEs. After recalling the Gaussian behavior at infinity of the kernel, we show some mean value formulas on the level sets of the fundamental solution, which are the starting point to obtain a comprehensive parallel of the classical Potential Theory. Then we show that a precise knowledge of the fundamental solution leads to global regularity results, namely estimates at the boundary or on the whole space. Finally in the problem of regularity of non linear differential equations we need an ad hoc modification of the parametrix method, based on the properties of the fundamental solution of an approximating problem
- âŠ