Geomagnetic field observations in Antarctica at the geomagnetic observatories at Terra Nova Bay and DomeC

During the 1986-87 austral summer a geomagnetic observatory was installed at the Italian Antarctic Base Mario Zucchelli Station (TNB, geographic coordinates:74.7S, 164.1E; corrected geomagnetic coordinates: 80.0S, 307.7E; magnetic local time MLT=UT-8). In the first years the measurements of the geomagnetic field were carried out only during summer expeditions. Since 1991 the recording was implemented with an automatic acquisition system operating through the year. More recently,after two short test surveys, from October 2004 a geomagnetic French-Italian observatory was installed on the Antarctic plateau (Dome C, DMC), very close to the geomagnetic pole (geographic coordinates: 75.1S, 123.4E; corrected geomagnetic coordinates:88.8S, 55.6E; magnetic local time MLT=UT-1). In this work we present some results obtained from TNB observations coming from almost twenty years of observations and also the preliminary results obtained from the analysis of the first year of data from DMC

Impacts of misalignment effects on the Muon Spectrometer Performance

The ATLAS detector, currently being installed at CERN, is designed to exploit the full potential of the LHC, identifying and providing highly accurate energy and momentum measurements of particles emerging from the LHC protonproton collisions with a centre-of-mass energy at 14 TeV, starting in 2007. High-momentum final-state muons are among the most promising signatures at the LHC, thanks to a high-resolution Muon Spectrometer with standalone triggering and momentum measurement. As well known, muons interact primarily trough their electromagnetic charge, but since they are 200 times more massive than the electrons they are less affected by the electric fields of the nuclei they encounter. Muons with an energy of more than a few GeV penetrate the calorimeter and can reach the Muon Spectrometer, which consists out of more than 1.200 single drift-tubes chambers. The correct alignment of the ATLAS Muon Spectrometer is crucial to ensure its design performance. This note documents the first attempt at using various misaligned Muonspectrometer layouts to study their impacts Muon Spectrometer performance

Self-forces on extended bodies in electrodynamics

In this paper, we study the bulk motion of a classical extended charge in flat spacetime. A formalism developed by W. G. Dixon is used to determine how the details of such a particle's internal structure influence its equations of motion. We place essentially no restrictions (other than boundedness) on the shape of the charge, and allow for inhomogeneity, internal currents, elasticity, and spin. Even if the angular momentum remains small, many such systems are found to be affected by large self-interaction effects beyond the standard Lorentz-Dirac force. These are particularly significant if the particle's charge density fails to be much greater than its 3-current density (or vice versa) in the center-of-mass frame. Additional terms also arise in the equations of motion if the dipole moment is too large, and when the `center-of-electromagnetic mass' is far from the `center-of-bare mass' (roughly speaking). These conditions are often quite restrictive. General equations of motion were also derived under the assumption that the particle can only interact with the radiative component of its self-field. These are much simpler than the equations derived using the full retarded self-field; as are the conditions required to recover the Lorentz-Dirac equation.Comment: 30 pages; significantly improved presentation; accepted for publication in Phys. Rev.

Idiopathic orthostatic hypotension: Recent data (eleven cases) and review of the literature

Eight cases of Shy-Drager syndrome and three of Bradbury-Eggleston idiopathic orthostatic hypotension were examined. In all cases, examination of circulatory reflexes showed major dysfunction of the sympathetic vasoconstrictor system. Anomalies in the vagal cardiomoderator system were less constant. Normal urinary elimination of catecholamines was recorded daily. Characteristically, no elevation of blood or urine norepinephrine levels were found in orthostatism. Insulin hypoglycemia normally raised urinary adrenalin elimination in three of ten patients. Plasma dopa-beta-hydroxylase activity was normal. Renin-angiotensin-aldosterone system showed variable activity at basal state but usually rose during orthostatism. On the average, very low homovanillic acid levels were found in cerebrospinal fluid before and after probenecid; hydroxyindolacetic acid was normal. Cerebral autoregulation had deteriorated in two of four cases. Physiopathologically the two clinical types are indistinguishable with or without central neurological signs

Characterization of the angular memory effect of scattered light in biological tissues.

This is the final version of the article. Available via open access from Optical Society of America via the DOI in this record.High resolution optical microscopy is essential in neuroscience but suffers from scattering in biological tissues and therefore grants access to superficial brain layers only. Recently developed techniques use scattered photons for imaging by exploiting angular correlations in transmitted light and could potentially increase imaging depths. But those correlations ('angular memory effect') are of a very short range and should theoretically be only present behind and not inside scattering media. From measurements on neural tissues and complementary simulations, we find that strong forward scattering in biological tissues can enhance the memory effect range and thus the possible field-of-view by more than an order of magnitude compared to isotropic scattering for ∼1 mm thick tissue layers.This work was funded by European Research Council Grant 278025 and the Agence Nationale de la Recherche (Investissements d’Avenir ANR-10-LABX-54 MEMO LIFE, ANR-11-IDEX- 0001-02 PSL* Research University). We thank Prof. Georg Maret for enabling Sam Schott’s stay at institut Langevin and his support of the project and David Martina for technical help in the development of the experimental setup

Geomagnetic field observations in Antarctica at the geomagnetic observatories at Terra Nova Bay and DomeC

During the 1986-87 austral summer a geomagnetic observatory was installed at the Italian Antarctic Base Mario Zucchelli Station (TNB, geographic coordinates:74.7S, 164.1E; corrected geomagnetic coordinates: 80.0S, 307.7E; magnetic local time MLT=UT-8). In the first years the measurements of the geomagnetic field were carried out only during summer expeditions. Since 1991 the recording was implemented with an automatic acquisition system operating through the year. More recently,after two short test surveys, from October 2004 a geomagnetic French-Italian observatory was installed on the Antarctic plateau (Dome C, DMC), very close to the geomagnetic pole (geographic coordinates: 75.1S, 123.4E; corrected geomagnetic coordinates:88.8S, 55.6E; magnetic local time MLT=UT-1). In this work we present some results obtained from TNB observations coming from almost twenty years of observations and also the preliminary results obtained from the analysis of the first year of data from DMC

Experimental determination of the degree of quantum polarisation of continuous variable states

We demonstrate excitation-manifold resolved polarisation characterisation of continuous-variable (CV) quantum states. In contrast to traditional characterisation of polarisation that is based on the Stokes parameters, we experimentally determine the Stokes vector of each excitation manifold separately. Only for states with a given photon number does the methods coincide. For states with an indeterminate photon number, for example Gaussian states, the employed method gives a richer and more accurate description. We apply the method both in theory and in experiment to some common states to demonstrate its advantages.Comment: 5 page

Towards the Opening of a Magnetic Observatory at Dome C (Antarctica)

The opening of a new magnetic observatory is one of the activities aimed at by the creation of a scientific base at DomeC, Antarctica (lat. 75° 06’S, long. 123° 21’E, elev. 3200m). There are many reasons supporting this objective: all Antarctic magnetic observatories providing absolute values are located along the shore and are therefore subject to coast effects and crustal field contamination. DomeC and Vostok will be so far the sole observatories free from these effects. On one hand, high latitude absolute observatories are very useful to global or regional modeling based upon satellite data, because, at high latitudes, only total field measurements can be used due to the strong influence of field aligned currents. On the other hand, the availability of magnetic data from the well distributed observatories of Terra Nova Bay (TNB), Scott Base (SBA), Dumont d’Urville (DRV), Casey (CSY) and Vostok (VOS) will provide strong support to auroral and polar cap ionosphere studies as well as asymmetry analyses between Northern and Southern hemispheres. This paper summarizes the results gathered during three summer campaigns, in 1999-2000, 2001 and 2003-2004