Extended Non Linear Conformal Symmetry and DSR Velocities on the Physical Surface

The relation between Conformal generators and Magueijo Smolin Deformed Special Relativity term, added to Lorentz boosts, is achieved. The same is performed for Fock Lorentz transformations. Through a dimensional reduction procedure, it is demonstrated that a massless relativistic particle living in a $d$ dimensional space, is isomorphic to one living in a $d+2$ space with pure Lorentz invariance and to a particle living in a $AdS_{d+1}$ space. To accomplish these identifications, the Conformal Group is extended and a nonlinear algebra arises. Finally, because the relation between momenta and velocities is known, the problem of position space dynamics is solved.Comment: totally renewe

Identification of new Keynesian Phillips curves from a global perspective

This paper is concerned with the estimation of New Keynesian Phillips Curves (NKPC) and focuses on two issues: the weak instrument problem and the characterization of the steady states. It proposes some solutions from a global perspective. Using a global vector autoregressive (GVAR) model steady states are estimated as long-horizon expectations and valid instruments are constructed from the global variables as weighted averages. The proposed estimation strategy is illustrated using estimates of the NKPC for eight developed industrial countries. The GVAR generates global factors that are valid instruments and help alleviate the weak instrument problem. The steady states also reflect global influences and any long-run theoretical relationships that might prevail within and across countries in the global economy. The GVAR measure of the steady state performed better than the HP measure, and the use of foreign instruments substantially increased the precision of the estimates of the output coefficient

Supply, demand and monetary policy shocks in a multi-country new Keynesian model

This paper estimates and solves a multi-country version of the standard DSGE New Keynesian (NK) model. The country-specific models include a Phillips curve determining inflation, an IS curve determining output, a Taylor Rule determining interest rates, and a real effective exchange rate equation. The IS equation includes a real exchange rate variable and a countryspecific foreign output variable to capture direct inter-country linkages. In accord with the theory all variables are measured as deviations from their steady states, which are estimated as long-horizon forecasts from a reduced-form cointegrating global vector autoregression. The resulting rational expectations model is then estimated for 33 countries on data for 1980Q1-2006Q4, by inequality constrained IV, using lagged and contemporaneous foreign variables as instruments, subject to the restrictions implied by the NK theory. The multi-country DSGE NK model is then solved to provide estimates of identified supply, demand and monetary policy shocks. Following the literature, we assume that the within country supply, demand and monetary policy shocks are orthogonal, though shocks of the same type (e.g. supply shocks in different countries) can be correlated. We discuss estimation of impulse response functions and variance decompositions in such large systems, and present estimates allowing for both direct channels of international transmission through regression coefficients and indirect channels through error spillover effects. Bootstrapped error bands are also provided for the cross country responses of a shock to the US monetary policy

Prospect for relic neutrino searches

Unlike the relic photons, relic neutrinos have not so far been observed. The Cosmic Neutrino Background (C$\nu$B) is the oldest relic from the Big Bang, produced a few seconds after the Bang itself. Due to their impact in cosmology, relic neutrinos may be revealed indireclty in the near future through cosmological observations. In this talk we concentrate on other proposals, made in the last 30 years, to try to detect the C$\nu$B directly, either in laboratory searches (through tiny accelerations they produce on macroscopic targets) or through astrophysical observations (looking for absorption dips in the flux of Ultra-High Energy neutrinos, due to the annihilation of these neutrinos with relic neutrinos at the Z-resonance). We concentrate mainly on the first of these two possibilities.Comment: Talk given at the Nobel Symposium on Neutrino Physics, Enkoping, Sweden, Augus 19-24, 2004; 16 page

The Children's Revised Impact of Event Scale (CRIES):Validity as a screening instrument for PTSD

The Children's Revised Impact of Event Scale (CRIES) is a brief child-friendly measure designed to screen children at risk for Posttraumatic Stress Disorder (PTSD). It has good face and construct validity, a stable factor structure, correlates well with other indices of distress, and has been used to screen very large samples of at-risk-children following a wide range of traumatic events. However, few studies have examined the scale's validity against a structured diagnostic interview based on the DSM-IV criteria for PTSD. In the present study, the CRIES and the PTSD section of the Anxiety Disorders Interview Schedule-Child and Parent Version (ADIS-CP) were administered to a sample of children and adolescents (n=63) recruited from hospital accident and emergency rooms and the validity of the CRIES as a screening tool evaluated. Cutoff scores were chosen from this sample with a low base-rate of PTSD (11.1%) to maximize sensitivity and minimize the likelihood that children with a diagnosis of PTSD would fail to be identified. Cutoff scores were then cross-validated in a sample of 52 clinically referred children who had a high base-rate of PTSD (67.3%). A cutoff score of 30 on the CRIES-13 and a cutoff score of 17 on the CRIES-8 maximized sensitivity and specificity, minimized the rate of false negatives, and correctly classified 75-83% of the children in the two samples. The CRIES-8 (which lacks any arousal items) worked as efficiently as the CRIES-13 (which includes arousal items) in correctly classifying children with and without PTSD. Results are discussed in light of the current literature and of the need for further development of effective screens for children at-risk of developing PTSD

GpsTunes: controlling navigation via audio feedback

We combine the functionality of a mobile Global Positioning System (GPS) with that of an MP3 player, implemented on a PocketPC, to produce a handheld system capable of guiding a user to their desired target location via continuously adapted music feedback. We illustrate how the approach to presentation of the audio display can benefit from insights from control theory, such as predictive 'browsing' elements to the display, and the appropriate representation of uncertainty or ambiguity in the display. The probabilistic interpretation of the navigation task can be generalised to other context-dependent mobile applications. This is the first example of a completely handheld location- aware music player. We discuss scenarios for use of such systems

The Optical Polarization Properties of X-ray Selected BL Lacertae Objects

We discuss the optical polarization properties of X-ray selected BL Lacertae objects (XSBLs) as determined from three years of monitoring 37 BL Lac objects and candidates. The observed objects include a complete X-ray flux limited sample drawn from the EMS Survey. The majority of the XSBLs classi- fied solely on the appearance of their spectra are members of the class of BL~Lacs since they possess intrinsically polarized and variable continua. The duty cycle of polarized emission from XSBLs is 40\%. The majority of XSBLs ($\approx 85$\%) have preferred polarization position angles on time scales as long as three years. This reflects stability in the geometry of the region emitting the polarized optical emission. We discuss the observed spectral dependence of the degree of polarization and some of the possible mechanisms for producing the observed characteristics. While dilution of the polarized emission by the host galaxy starlight is present in some objects, we demon- strate that the average polarization properties derived from our observations are not drastically affected by this effect. The objects in our monitored sample did not display the larger than one magnitude variations generally used to characterize the optical variability of blazars in general.Comment: LaTex file, 21 pages, with tables appended as a poscript file. Contact [email protected] for postscript figure files. Institute for Advanced Study number AST 93/4