Relative and Absolute Mappings for Rotating Remote 3D Objects on Multi-Touch Tabletops

The use of human fingers as an object selection and manipulation tool has raised significant challenges when interacting with direct-touch tabletop displays. This is particularly an issue when manipulating remote objects in 3D environments as finger presses can obscure objects at a distance that are rendered very small. Techniques to support remote manipulation either provide absolute mappings between finger presses and object transformation or rely on tools that support relative mappings t o selected objects. This paper explores techniques to manipulate remote 3D objects on direct-touch tabletops using absolute and relative mapping modes. A user study was conducted to compare absolute and relative mappings in support of a rotation task. Overall results did not show a statistically significant difference between these two mapping modes on both task completion time and the number of touches. However, the absolute mapping mode was found to be less efficient than the relative mapping mode when rotating a small object. Also participants preferred relative mapping for small objects. Four mapping techniques were then compared for perceived ease of use and learnability. Touchpad, voodoo doll and telescope techniques were found to be comparable for manipulating remote objects in a 3D scene. A flying camera technique was considered too complex and required increased effort by participants. Participants preferred an absolute mapping technique augmented to support small object manipulation, e.g. the voodoo doll technique

Self-Screening Hawking Atmosphere in the Presence of a Bulk Viscosity

The recent theory of 't Hooft [ Nucl. Phys. Suppl. {\bf 68}, 174 (1998)] models the black hole as a system endowed with an envelope of matter that obeys an equation of state in the form $p=(\gamma -1)\rho$, and acts as a source in Einstein's equations. The present paper generalizes the 't Hooft theory so as to take into account a bulk viscosity $\zeta$ in the fluid. It is shown that even a slight positive value of $\zeta$ will suffice to yield complete agreement with the Hawking formula for the entropy of the black hole, if the value of the constant $\gamma$ takes a value that is slightly less than 4/3. The value $\gamma=4/3$ corresponds to a radiation fluid.Comment: 12 pages, LaTeX, no figures, minor extensions of the discussion. To appear in PR

Electrical conductivity of the Pampean Shallow Subduction Region of Argentina near 33 S: evidence for a slab window

We present a three-dimensional (3-D) interpretation of 117 long period (20–4096 s) magnetotelluric (MT) sites between 31°S and 35°S in western Argentina. They cover the most horizontal part of the Pampean shallow angle subduction of the Nazca Plate and extend south into the more steeply dipping region. Sixty-two 3-D inversions using various smoothing parameters and data misfit goals were done with a nonlinear conjugate gradient (NLCG) algorithm. A dominant feature of the mantle structure east of the horizontal slab is a conductive plume rising from near the top of the mantle transition zone at 410 km to the probable base of the lithosphere at 100 km depth. The subducted slab is known to descend to 190 km just west of the plume, but the Wadati-Benioff zone cannot be traced deeper. If the slab is extrapolated downdip it slices through the plume at 250 km depth. Removal of portions of the plume or blocking vertical current flow at 250 km depth significantly changes the predicted responses. This argues that the plume is not an artifact and that it is continuous. The simplest explanation is that there is a “wedge”-shaped slab window that has torn laterally and opens down to the east with its apex at the plume location. Stress within the slab and seismic tomography support this shape. Its northern edge likely explains why there is no deep seismicity south of 29°S.Fil: Burd, Aurora I.. University of Washington; Estados UnidosFil: Booker, John R.. University of Washington; Estados UnidosFil: Mackie, Randall. Land General Geophysics; ItaliaFil: Pomposiello, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotopica; ArgentinaFil: Favetto, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotopica; Argentin

Grd19/Snx3p functions as a cargo-specific adapter for retromer-dependent endocytic recycling

Amajor function of the endocytic system is the sorting of cargo to various organelles. Endocytic sorting of the yeast reductive iron transporter, which is composed of the Fet3 and Ftr1 proteins, is regulated by available iron. When iron is provided to iron-starved cells, Fet3p–Ftr1p is targeted to the lysosome-like vacuole and degraded. In contrast, when iron is not available, Fet3p–Ftr1p is maintained on the plasma membrane via an endocytic recycling pathway requiring the sorting nexin Grd19/Snx3p, the pentameric retromer complex, and the Ypt6p Golgi Rab GTPase module. A recycling signal in Ftr1p was identified and found to bind directly to Grd19/Snx3p. Retromer and Grd19/Snx3p partially colocalize to tubular endosomes, where they are physically associated. After export from the endosome, Fet3p–Ftr1p transits through the Golgi apparatus for resecretion. Thus, Grd19/Snx3p, functions as a cargo-specific adapter for the retromer complex, establishing a precedent for a mechanism by which sorting nexins expand the repertoire of retromer-dependent cargos

Chaotic Friedmann-Robertson-Walker Cosmology

We show that the dynamics of a spatially closed Friedmann - Robertson - Walker Universe conformally coupled to a real, free, massive scalar field, is chaotic, for large enough field amplitudes. We do so by proving that this system is integrable under the adiabatic approximation, but that the corresponding KAM tori break up when non adiabatic terms are considered. This finding is confirmed by numerical evaluation of the Lyapunov exponents associated with the system, among other criteria. Chaos sets strong limitations to our ability to predict the value of the field at the Big Crunch, from its given value at the Big Bang. (Figures available on request)Comment: 28 pages, 11 figure

Clinical investigation of an outbreak of alveolitis and asthma in a car engine manufacturing plant

Background Exposure to metal working fluid (MWF) has been associated with outbreaks of EAA in the US, with bacterial contamination of MWF being a possible cause, but was uncommon in the UK. Twelve workers developed extrinsic allergic alveolitis (EAA) in a car engine manufacturing plant in the UK, presenting clinically between December 2003 and May 2004. This paper reports the subsequent epidemiological investigation of the whole workforce. This had three aims:- • To measure the extent of the outbreak by identifying other workers who may have developed EAA or other work-related respiratory diseases. • To provide case-detection so that those affected can be treated. • To provide epidemiological data to identify the cause of the outbreak. Methods The outbreak was investigated in a three-phase cross-sectional survey of the workforce. Phase I A respiratory screening questionnaire was completed by 808/836 workers (96.7%) in May 2004. Phase II 481 employees with at least one respiratory symptom on screening and 50 asymptomatic controls were invited for investigation at the factory in June 2004. This included a questionnaire, spirometry and clinical opinion. 454/481(94.4%) responded along with 48/50(96%) controls. Workers were identified who needed further investigation and serial measurements of peak expiratory flow (PEF). Phase III 162 employees were seen at the Birmingham Occupational Lung Disease clinic. 198 employees returned PEF records, including 141 of the 162 who attended for clinical investigation. Case definitions for diagnoses were agreed. Results 87 workers (10.4% of workforce) met case definitions for occupational lung disease, comprising EAA(19), occupational asthma(74) and humidifier fever(7). 12 workers had more than one diagnosis. The peak onset of work-related breathlessness was Spring 2003. The proportion of workers affected was higher for those using metal working fluid (MWF) from a large sump(27.3%) compared with working all over the manufacturing area (7.9%) (OR=4.39,p<0.001). Two workers had positive specific provocation tests to the used but not the unused MWF solution. Conclusions Extensive investigation of the outbreak of EAA detected a large number of affected workers, not only with EAA but also occupational asthma. This is the largest reported outbreak in Europe. Mist from used MWF is the likely cause. In workplaces using MWF, there is a need to carry out risk assessments, to monitor and maintain fluid quality, to control mist and to carry out respiratory health surveillance

On homothetic cosmological dynamics

We consider the homogeneous and isotropic cosmological fluid dynamics which is compatible with a homothetic, timelike motion, equivalent to an equation of state $\rho + 3P = 0$. By splitting the total pressure $P$ into the sum of an equilibrium part $p$ and a non-equilibrium part $\Pi$, we find that on thermodynamical grounds this split is necessarily given by $p = \rho$ and $\Pi = - (4/3)\rho$, corresponding to a dissipative stiff (Zel'dovich) fluid.Comment: 8 pages, to be published in Class. Quantum Gra

Chaos in Anisotropic Pre-Inflationary Universes

We study the dynamics of anisotropic Bianchi type-IX models with matter and cosmological constant. The models can be thought as describing the role of anisotropy in the early stages of inflation. The concurrence of the cosmological constant and anisotropy are sufficient to produce a chaotic dynamics in the gravitational degrees of freedom, connected to the presence of a critical point of saddle-center type in the phase space of the system. The invariant character of chaos is guaranteed by the topology of the cylinders emanating from unstable periodic orbits in the neighborhood of the saddle-center. We discuss a possible mechanism for amplification of specific wavelengths of inhomogeneous fluctuations in the models. A geometrical interpretation is given for Wald's inequality in terms of invariant tori and their destruction by increasing values of the cosmological constant.Comment: 14 pages, figures available under request. submitted to Physical Review

On the Cosmology of Massive Vector Fields with SO(3) Global Symmetry

A relevant reference ([14]) has been added.Comment: 19 pages, plain tex, DF/IST-3/92 and DFFCUL 03-5/199

On the Realization of Assisted Inflation

We consider conditions necessary for a successful implementation of so-called assisted inflation. We generalize the applicability of assisted inflation beyond exponential potentials as originally proposed to include standard chaotic (\lambda \phi^4 or m^2 \phi^2) models as well. We also demonstrate that in a purely 4-dimensional theory, unless the assisted sector is in fact decoupled, the additional fields of the assisted sector actually impede inflation. As a specific example of an assisted sector, we consider a 5-dimensional KK model for which the extra dimension may be somewhat or much larger than the inverse Planck scale. In this case, the assisted sector (coming from a KK compactification) eliminates the need for a fine-tuned quartic coupling to drive chaotic inflation. This is a general result of models with one or more "large" extra dimensions.Comment: 25 pages, LaTeX fil