Wideband digital phase comparator for high current shunts

A wideband phase comparator for precise measurements of phase difference of high current shunts has been developed at INRIM. The two-input digital phase detector is realized with a precision wideband digitizer connected through a pair of symmetric active guarded transformers to the outputs of the shunts under comparison. Data are first acquired asynchronously, and then transferred from on-board memory to host memory. Because of the large amount of data collected the filtering process and the analysis algorithms are performed outside the acquisition routine. Most of the systematic errors can be compensated by a proper inversion procedure. The system is suitable for comparing shunts in a wide range of currents, from several hundred of milliampere up to 100 A, and frequencies ranging between 500 Hz and 100 kHz. Expanded uncertainty (k=2) less than 0.05 mrad, for frequency up to 100 kHz, is obtained in the measurement of the phase difference of a group of 10 A shunts, provided by some European NMIs, using a digitizer with sampling frequency up to 1 MHz. An enhanced version of the phase comparator employs a new digital phase detector with higher sampling frequency and vertical resolution. This permits to decrease the contribution to the uncertainty budget of the phase detector of a factor two from 20 kHz to 100 kHz. Theories and experiments show that the phase difference between two high precision wideband digitizers, coupled as phase detector, depends on multiple factors derived from both analog and digital imprint of each sampling system.Comment: 20 pages, 9 figure

Investigating on the nuclear obscuration in two types of Seyfert 2 galaxies

We build a large sample of Seyfert 2 galaxies (Sy2s) with both optical spectropolarimetric and X-ray data available, in which 29 Sy2s with the detection of polarized broad emission line (PBL) and 25 without. We find that for luminous Sy2s with L_[OIII] > 10^41 erg/s, sources with PBL have smaller X-ray absorption column density comparing with those without PBL (at 92.3% confidence level): most of the Sy2s with N_H<10^23.8 cm^-2 show PBL (86%, 12 out 14), while the fraction is much smaller for sources with heavier obscuration (54%, 15 out 28). The confidence level of the difference in absorption bounces up to 99.1% while using the "T" ratio (F_2-10keV/F_[O III]) as an indicator. We rule out observation or selection bias as the origin for the difference. Our results, for the first time with high statistical confidence, show that, in additional to the nuclei activity, the nuclear obscuration also plays an important role in the visibility of PBL in Sy2s. These results can be interpreted in the framework of the unified model. We can reach these results in the unified model if: a) the absorption column density is higher at large inclinations and b) the scattering region is obscured at large inclinations.Comment: 28 pages, including 7 figures and 3 tables, ApJ accepte

The development of policing in Britain in the next five years.

The British police service is currently going through a radical transformation phase. The present Tory-led coalition government has set out an agenda to bring about drastic changes in policing. These proposed changes are unprecedented in the history of policing since 1829. The police service is governed by a tripartite arrangement of checks and balances laid down under the Police Act 1964. By this I mean that there are three key players in relation to police governance in Britain: the Home Secretary, the local police authority and the chief constable. The future of policing in the next five years is set out clearly by the Home Secretary, Theresa May MP, under the Police Reform and Social Responsibility Bill, which is currently being reviewed in the House of Lords. The recent phone hacking scandal has made it imperative for the British public to have a closer look at the police service in relation to proper accountability. There have been references to police corruption as far back as the era of 'parish constables', dating back to 1800, when it was alleged that police officers took bribes, got drunk whilst on duty and lacked moral credibility to protect and serve us (Critchley, 1978). In the seventies and eighties the British public was informed of another scandal involving members of Scotland Yard and criminal gangs in the East End of London. In this article, I shall argue that the issue of police corruption is not a new phenomenon. It is has been an ongoing issue that has haunted the police for over a century. This article is divided into three parts. In the first part of the article I present the following issues: the Metropolitan Police policing plan 2011-2014; the merits and demerits of the policing plan; tripartite police accountability and its shortcomings; democratic accountability and localisation of policing; the professionalisation of policing and the creation of the Police Body; review of police pay and benefits; and the impact of this on police officers' morale. In the second part of my article I present some of the criticisms levelled against the ongoing police reforms. I will look at the criticisms from both internal and external perspectives. By internal criticism, I mean police officers' opposition to the reforms. By external criticism, I mean criticisms from criminologists and members of the British public. In the third part of my article I made my position clear on where I stand in relation to the ongoing police reforms. I shall argue that the current ongoing job cuts in the police service are a disaster waiting to happen, and that our safety has been compromised by politicians. We are now living at the mercy of criminals and law breakers due to manpower shortage. We are all living witnesses to the ongoing public disturbances in Tottenham, Enfield, Brixton, Peckham, Walthamstow and Croydon, in London. The speed of the spread of these riots to other cities like Bristol, Birmingham, Manchester and Liverpool occurred on an unimaginable scale. We all watched how difficult it was for the police to restore order and normality. Rioters looted and plundered goods and burnt down buildings as if no laws existed in our country. A complete breakdown of law and order put the lives of citizens at risk. My article makes a passionate appeal to the present coalition government to rethink the issue of reducing the numbers of police officers protecting us. I shall argue that we need more police officers in Britain not fewer. The level of anger and social discontent is higher than the government ever anticipated, partly because of economic hardship. My argument is that economic hardship is not an excuse to commit burglary, theft, arson, murder and criminal damage with intent to endanger life. Rioters are shameless opportunists, a bunch of hoodlums, criminals who have no place in any civilised society, who should be made to face the due process of law

Time-odd mean fields in the rotating frame: microscopic nature of nuclear magnetism

The microscopic role of nuclear magnetism in rotating frame is investigated for the first time in the framework of the cranked relativistic mean field theory. It is shown that nuclear magnetism modifies the expectation values of single-particle spin, orbital and total angular momenta along the rotational axis effectively creating additional angular momentum. This effect leads to the increase of kinematic and dynamic moments of inertia at given rotational frequency and has an impact on effective alignments.Comment: 16 pages, 4 figures, submitted to Physical Review

Riemann's theorem for quantum tilted rotors

The angular momentum, angular velocity, Kelvin circulation, and vortex velocity vectors of a quantum Riemann rotor are proven to be either (1) aligned with a principal axis or (2) lie in a principal plane of the inertia ellipsoid. In the second case, the ratios of the components of the Kelvin circulation to the corresponding components of the angular momentum, and the ratios of the components of the angular velocity to those of the vortex velocity are analytic functions of the axes lengths.Comment: 8 pages, Phys. Rev.

A Radio Study of the Seyfert Galaxy IC 5063: Evidence for Fast Gas Outflow

New radio continuum (8 GHz and 1.4 GHz) and HI 21 cm line observations of the Seyfert 2 galaxy IC 5063 (PKS 2048-572) were obtained with the Australia Telescope Compact Array (ATCA). The 8 GHz image reveals a linear triple structure (~4'', 1.5 kpc) oriented perpendicular to the optical polarization position angle. It is aligned with the inner dust lane and shows strong morphological association with the narrow emission line region (NLR). At 21 cm, very broad (~700 km/s) HI absorption is observed against the strong continuum source. This absorption is almost entirely blueshifted, indicating a fast net outflow, but a faint and narrow redshifted component is also present. In IC 5063 we see clear evidence for strong shocks resulting from the radio plasma-ISM interaction in the central few kpc. However, the energy flux in the radio plasma is an order of magnitude smaller than the energy emitted in emission lines. Thus, shocks are unlikely to account solely for the global ionization of the emission line region, particularly at large distances. The HI emission outlines a warped disk associated with the system of dust lanes some ~2' (~38 kpc) in radius. The lack of kinematically disturbed gas outside the central few kpc, coupled with the disk warp and close morphological connection of the inner dust lanes and the large-scale ionized gas, support the idea that the gas at large radii is photoionized by the central region, while shadowing effects are important in defining its X-shaped morphology. The kinematics of the ionized and of the neutral gas suggests the existence of a dark halo.Comment: 18 pages, 8 Postscript figures, 3 jpeg figures, Postscript preprint is available from http://jhufos.pha.jhu.edu/~zlatan/papers.htm

Self-consistent anisotropic oscillator with cranked angular and vortex velocities

The Kelvin circulation is the kinematical Hermitian observable that measures the true character of nuclear rotation. For the anisotropic oscillator, mean field solutions with fixed angular momentum and Kelvin circulation are derived in analytic form. The cranking Lagrange multipliers corresponding to the two constraints are the angular and vortex velocities. Self-consistent solutions are reported with a constraint to constant volume.Comment: 12 pages, LaTex/RevTex, Phys. Rev. C4

The Unified Model & Evolution of Active Galaxies: Implications from a Spectropolarimetric Study

We extend the analysis presented in Tran (2001) of a spectropolarimetric survey of the CfA and 12micron samples of Seyfert 2 galaxies (S2s). We confirm that S2s with hidden broad line regions (HBLRs) tend to have hotter circumnuclear dust temperatures, show mid-IR spectra more characteristic of S1 galaxies, and are intrinsically more luminous than non-HBLR S2s. The level of obscuration and circumnuclear star formation, however, appear to be similar between HBLR and non-HBLR S2 galaxies, based on an examination of various observational indicators. HBLR S2s, on average, share many similar large-scale, presumably isotropic, characteristics with Seyfert 1 galaxies (S1s), as would be expected if the unified model is correct, while non-HBLR S2s generally do not. The active nuclear engines of non-HBLR S2s then, appear to be truly weaker than HBLR S2s, which in turn, are fully consistent with being S1s viewed from another direction. There is also evidence that the fraction of detected HBLR increases with radio power of the AGN. Thus, not all Seyfert 2 galaxies may be intrinsically similar in nature, and we speculate that evolutionary processes may be at work.Comment: 15 pages with embedded figs, ApJ in press, vol. 583, 2003 Feb. 1. v2: minor corrections to text, some typos removed; updated reference list: some added, some remove