Non-Linear Deformations of Liquid-Liquid Interfaces Induced by Electromagnetic Radiation Pressure

The idea of working with a near-critical phase-separated liquid mixture whereby the surface tension becomes weak, has recently made the field of laser manipulation of liquid interfaces a much more convenient tool in practice. The deformation of interfaces may become as large as several tenths of micrometers, even with the use of conventional laser power. This circumstance necessitates the use of nonlinear geometrical theory for the description of surface deformations. The present paper works out such a theory, for the surface deformation under conditions of axial symmetry and stationarity. Good agreement is found with the experimental results of Casner and Delville [A. Casner and J. P. Delville, Phys. Rev. Lett. {\bf 87}, 054503 (2001); Opt. Lett. {\bf 26}, 1418 (2001); Phys. Rev. Lett. {\bf 90}, 144503 (2003)], in the case of moderate power or a broad laser beam. In the case of large power and a narrow beam, corresponding to surface deformations of about 50 micrometers or higher, the theory is found to over-predict the deformation. Possible explanations of this discrepancy are discussed.Comment: RevTeX4, 19 pages, 4 figures. Sec. IIIB rewritten, 4 new references. To appear in Phys. Rev.

The Hall current system revealed as a statistical significant pattern during fast flows

We have examined the dawn-dusk component of the magnetic field, <I>B<sub>Y</sub></I>, in the night side current sheet during fast flows in the neutral sheet. 237 h of Cluster data from the plasma sheet between 2 August 2002 and 2 October 2002 have been analysed. The spatial pattern of <I>B<sub>Y</sub></I> as a function of the distance from the centre of the current sheet has been estimated by using a Harris current sheet model. We have used the average slopes of these patterns to estimate earthward and tailward currents. For earthward fast flows there is a tailward current in the inner central plasma sheet and an earthward current in the outer central plasma sheet on average. For tailward fast flows the currents are oppositely directed. These observations are interpreted as signatures of Hall currents in the reconnection region or as field aligned currents which are connected with these currents. Although fast flows often are associated with a dawn-dusk current wedge, we believe that we have managed to filter out such currents from our statistical patterns

Oxygen and hydrogen ion abundance in the near-Earth magnetosphere: Statistical results on the response to the geomagnetic and solar wind activity conditions

The composition of ions plays a crucial role for the fundamental plasma properties in the terrestrial magnetosphere. We investigate the oxygen-to-hydrogen ratio in the near-Earth magnetosphere from -10 RE<XGSE}< 10 RE. The results are based on seven years of ion flux measurements in the energy range ~10 keV to ~955 keV from the RAPID and CIS instruments on board the Cluster satellites. We find that (1) hydrogen ions at ~10 keV show only a slight correlation with the geomagnetic conditions and interplanetary magnetic field changes. They are best correlated with the solar wind dynamic pressure and density, which is an expected effect of the magnetospheric compression; (2) ~10 keV O+ ion intensities are more strongly affected during disturbed phase of a geomagnetic storm or substorm than >274 keV O+ ion intensities, relative to the corresponding hydrogen intensities; (3) In contrast to ~10 keV ions, the >274 keV O+ ions show the strongest acceleration during growth phase and not during the expansion phase itself. This suggests a connection between the energy input to the magnetosphere and the effective energization of energetic ions during growth phase; (4) The ratio between quiet and disturbed times for the intensities of ion ionospheric outflow is similar to those observed in the near-Earth magnetosphere at >274 keV. Therefore, the increase of the energetic ion intensity during disturbed time is more likely due to the intensification than to the more effective acceleration of the ionospheric source. In conclusion, the energization process in the near-Earth magnetosphere is mass dependent and it is more effective for the heavier ions

More about arc-polarized structures in the solar wind

We report results from a Cluster-based study of the properties of 28 arc-polarized magnetic structures (also called rotational discontinuities) in the solar wind. These Alfve ́nic events were selected from the database created and analyzed by Knetter (2005) by use of criteria chosen to elim- inate ambiguous cases. His studies showed that standard, four-spacecraft timing analysis in most cases lacks sufficient accuracy to identify the small normal magnetic field compo- nents expected to accompany such structures, leaving unan- swered the question of their existence. Our study aims to break this impasse. By careful application of minimum vari- ance analysis of the magnetic field (MVAB) from each indi- vidual spacecraft, we show that, in most cases, a small but significantly non-zero magnetic field component was present in the direction perpendicular to the discontinuity. In the very few cases where this component was found to be large, ex- amination revealed that MVAB had produced an unusual and unexplained orientation of the normal vector. On the whole, MVAB shows that many verifiable rotational discontinuities (Bn ̸= 0) exist in the solar wind and that their eigenvalue ratio (EVR=intermediate/minimum variance) can be extremely large (up to EVR = 400). Each of our events comprises four individual spacecraft crossings. The events include 17 ion- polarized cases and 11 electron-polarized ones. Fifteen of the ion events have widths ranging from 9 to 21 ion iner- tial lengths, with two outliers at 46 and 54. The electron- polarized events are generally thicker: nine cases fall in the range 20–71 ion inertial lengths, with two outliers at 9 and 13. In agreement with theoretical predictions from a one- dimensional, ideal, Hall-MHD description (Sonnerup et al., 2010), the ion-polarized events show a small depression in field magnitude, while the electron-polarized ones tend to show a small enhancement

Magnetospheric convection from Cluster EDI measurements compared with the ground-based ionospheric convection model IZMEM

Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for more than seven and a half years (2001–2008) have been used to derive a statistical model of the high-latitude electric potential distribution for summer conditions. Based on potential pattern for different orientations of the interplanetary magnetic field (IMF) in the GSM y-z-plane, basic convection pattern (BCP) were derived, that represent the main characteristics of the electric potential distribution in dependence on the IMF. The BCPs comprise the IMF-independent potential distribution as well as patterns, which describe the dependence on positive and negative IMF&lt;I&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/I&gt; and IMF&lt;I&gt;B&lt;sub&gt;y&lt;/sub&gt;&lt;/I&gt; variations. The full set of BCPs allows to describe the spatial and temporal variation of the high-latitude electric potential (ionospheric convection) for any solar wind IMF condition near the Earth&apos;s magnetopause within reasonable ranges. The comparison of the Cluster/EDI model with the IZMEM ionospheric convection model, which was derived from ground-based magnetometer observations, shows a good agreement of the basic patterns and its variation with the IMF. According to the statistical models, there is a two-cell antisunward convection within the polar cap for northward IMF&lt;I&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/I&gt;+&amp;le;2 nT, while for increasing northward IMF&lt;I&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/I&gt;+ there appears a region of sunward convection within the high-latitude daytime sector, which assumes the form of two additional cells with sunward convection between them for IMF&lt;I&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/I&gt;+&amp;asymp;4–5 nT. This results in a four-cell convection pattern of the high-latitude convection. In dependence of the &amp;plusmn;IMF&lt;I&gt;B&lt;sub&gt;y&lt;/sub&gt;&lt;/I&gt; contribution during sufficiently strong northward IMF&lt;I&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/I&gt; conditions, a transformation to three-cell convection patterns takes place

Dawn–Dusk Asymmetries In The Coupled Solar Wind–Magnetosphere–Ionosphere System: A Review

Dawn–dusk asymmetries are ubiquitous features of the coupled solar-wind–magnetosphere–ionosphere system. During the last decades, increasing availability of satellite and ground-based measurements has made it possible to study these phenomena in more detail. Numerous publications have documented the existence of persistent asymmetries in processes, properties and topology of plasma structures in various regions of geospace. In this paper, we present a review of our present knowledge of some of the most pronounced dawn–dusk asymmetries. We focus on four key aspects: (1) the role of external influences such as the solar wind and its interaction with the Earth\u27s magnetosphere; (2) properties of the magnetosphere itself; (3) the role of the ionosphere and (4) feedback and coupling between regions. We have also identified potential inconsistencies and gaps in our understanding of dawn–dusk asymmetries in the Earth\u27s magnetosphere and ionosphere

ACT-Enhanced Behavior Therapy in Group Format for Trichotillomania: An Effectiveness Study

Background This study sought to investigate the effectiveness of group treatment for trichotillomania (TTM) in ordinary clinical settings. Treatment consisted of a combination of habit reversal training (HRT) and acceptance and commitment treatment (ACT). Both short- and long-term effects were explored, as well as individual change trajectories. Methods The sample consist of fifty-three patients with TTM. Treatment outcomes were evaluated at post-treatment and at one-year follow-up using self-report questionnaires (Massachusetts General Hospital Hair Pulling Scale, MGH-HS), structured clinical interviews (National Institute of Mental Health Trichotillomania Severity Scale, NIMH-TSS), and the Clinical Global Impression scale for TTM (CGI-TTM). Results Analyses by mixed models for repeated measurements yielded a statistically significant effect of time (p Conclusions ACT-enhanced behavior therapy in a group format seems efficient for reducing symptoms of trichotillomania

Genotyping errors in a calibrated DNA register: implications for identification of individuals

<p>Abstract</p> <p>Background</p> <p>The use of DNA methods for the identification and management of natural resources is gaining importance. In the future, it is likely that DNA registers will play an increasing role in this development. Microsatellite markers have been the primary tool in ecological, medical and forensic genetics for the past two decades. However, these markers are characterized by genotyping errors, and display challenges with calibration between laboratories and genotyping platforms. The Norwegian minke whale DNA register (NMDR) contains individual genetic profiles at ten microsatellite loci for 6737 individuals captured in the period 1997-2008. These analyses have been conducted in four separate laboratories for nearly a decade, and offer a unique opportunity to examine genotyping errors and their consequences in an individual based DNA register. We re-genotyped 240 samples, and, for the first time, applied a mixed regression model to look at potentially confounding effects on genotyping errors.</p> <p>Results</p> <p>The average genotyping error rate for the whole dataset was 0.013 per locus and 0.008 per allele. Errors were, however, not evenly distributed. A decreasing trend across time was apparent, along with a strong within-sample correlation, suggesting that error rates heavily depend on sample quality. In addition, some loci were more error prone than others. False allele size constituted 18 of 31 observed errors, and the remaining errors were ten false homozygotes (i.e., the <it>true </it>genotype was a heterozygote) and three false heterozygotes (i.e., the <it>true </it>genotype was a homozygote).</p> <p>Conclusions</p> <p>To our knowledge, this study represents the first investigation of genotyping error rates in a wildlife DNA register, and the first application of mixed models to examine multiple effects of different factors influencing the genotyping quality. It was demonstrated that DNA registers accumulating data over time have the ability to maintain calibration and genotyping consistency, despite analyses being conducted on different genotyping platforms and in different laboratories. Although errors were detected, it is demonstrated that if the re-genotyping of individual samples is possible, these will have a minimal effect on the database's primary purpose, i.e., to perform individual identification.</p

Laser acceleration of ion beams

We consider methods of charged particle acceleration by means of high-intensity lasers. As an application we discuss a laser booster for heavy ion beams provided, e.g. by the Dubna nuclotron. Simple estimates show that a cascade of crossed laser beams would be necessary to provide additional acceleration to gold ions of the order of GeV/nucleon.Comment: 4 pages, 4 figures, Talk at the Helmholtz International Summer School "Dense Matter in heavy Ion Collisions and Astrophysics", August 21 - September 1, 2006, JINR Dubna, Russia; v2, misprints correcte