[OI]63micron jets in class 0 sources detected by Herschel

We present Herschel PACS mapping observations of the [OI]63 micron line towards protostellar outflows in the L1448, NGC1333-IRAS4, HH46, BHR71 and VLA1623 star forming regions. We detect emission spatially resolved along the outflow direction, which can be associated with a low excitation atomic jet. In the L1448-C, HH46 IRS and BHR71 IRS1 outflows this emission is kinematically resolved into blue- and red-shifted jet lobes, having radial velocities up to 200 km/s. In the L1448-C atomic jet the velocity increases with the distance from the protostar, similarly to what observed in the SiO jet associated with this source. This suggests that [OI] and molecular gas are kinematically connected and that this latter could represent the colder cocoon of a jet at higher excitation. Mass flux rates (\.M$_{jet}$(OI)) have been measured from the [OI]63micron luminosity adopting two independent methods. We find values in the range 1-4 10$^{-7}$ Mo/yr for all sources but HH46, for which an order of magnitude higher value is estimated. \.M$_{jet}$(OI) are compared with mass accretion rates (\.M$_{acc}$) onto the protostar and with \.M$_{jet}$ derived from ground-based CO observations. \.M$_{jet}$(OI)/\.M$_{acc}$ ratios are in the range 0.05-0.5, similar to the values for more evolved sources. \.M$_{jet}$(OI) in HH46 IRS and IRAS4A are comparable to \.M$_{jet}$(CO), while those of the remaining sources are significantly lower than the corresponding \.M$_{jet}$(CO). We speculate that for these three sources most of the mass flux is carried out by a molecular jet, while the warm atomic gas does not significantly contribute to the dynamics of the system.Comment: 37 pages and 12 figures, accepted for publication on Astrophysical Journa

Genetically controlled environmental variance for sternopleural bristles in Drosophila melanogaster - an experimental test of a heterogeneous variance model

This is an Accepted Manuscript of an article published by Taylor & Francis in Acta Agriculturae Scandinavica Section A - Animal Science on2007, available online: http://doi.org/10.1080/09064700801959403[EN] objective of this study was to test the hypothesis that the environmental variance of sternopleural bristle number in Drosophila melanogaster is partly under genetic control. We used data from 20 inbred lines and 10 control lines to test this hypothesis. Two models were used: a standard quantitative genetics model based on the infinitesimal model, and an extension of this model. In the extended model it is assumed that each individual has its own environmental variance and that this heterogeneity of variance has a genetic component. The heterogeneous variance model was favoured by the data, indicating that the environmental variance is partly under genetic control. If this heterogeneous variance model also applies to livestock, it would be possible to select for animals with a higher uniformity of products across environmental regimes. Also for evolutionary biology the results are of interest as genes affecting the environmental variance may be important for adaptation to changing environmental conditions.Sørensen, AC.; Kristensen, TN.; Loeschcke, V.; Ibañez Escriche, N.; Sorensen, D. (2007). Genetically controlled environmental variance for sternopleural bristles in Drosophila melanogaster - an experimental test of a heterogeneous variance model. Acta Agriculturae Scandinavica Section A - Animal Science. 57(4):196-201. https://doi.org/10.1080/09064700801959403S19620157

Effect of bonding of a CO molecule on the conductance of atomic metal wires

We have measured the effect of bonding of a CO molecule on the conductance of Au, Cu, Pt, and Ni atomic contacts at 4.2 K. When CO gas is admitted to the metal nano contacts, a conductance feature appears in the conductance histogram near 0.5 of the quantum unit of conductance, for all metals. For Au, the intensity of this fractional conductance feature can be tuned with the bias voltage, and it disappears at high bias voltage (above $\sim$ 200 mV). The bonding of CO to Au appears to be weakest, and associated with monotomic Au wire formation.Comment: 6 figure

Scalable Group Level Probabilistic Sparse Factor Analysis

Many data-driven approaches exist to extract neural representations of functional magnetic resonance imaging (fMRI) data, but most of them lack a proper probabilistic formulation. We propose a group level scalable probabilistic sparse factor analysis (psFA) allowing spatially sparse maps, component pruning using automatic relevance determination (ARD) and subject specific heteroscedastic spatial noise modeling. For task-based and resting state fMRI, we show that the sparsity constraint gives rise to components similar to those obtained by group independent component analysis. The noise modeling shows that noise is reduced in areas typically associated with activation by the experimental design. The psFA model identifies sparse components and the probabilistic setting provides a natural way to handle parameter uncertainties. The variational Bayesian framework easily extends to more complex noise models than the presently considered.Comment: 10 pages plus 5 pages appendix, Submitted to ICASSP 1

Realization of efficient quantum gates with a superconducting qubit-qutrit circuit

Building a quantum computer is a daunting challenge since it requires good control but also good isolation from the environment to minimize decoherence. It is therefore important to realize quantum gates efficiently, using as few operations as possible, to reduce the amount of required control and operation time and thus improve the quantum state coherence. Here we propose a superconducting circuit for implementing a tunable system consisting of a qutrit coupled to two qubits. This system can efficiently accomplish various quantum information tasks, including generation of entanglement of the two qubits and conditional three-qubit quantum gates, such as the Toffoli and Fredkin gates. Furthermore, the system realizes a conditional geometric gate which may be used for holonomic (non-adiabatic) quantum computing. The efficiency, robustness and universality of the presented circuit makes it a promising candidate to serve as a building block for larger networks capable of performing involved quantum computational tasks.Comment: 27 pages including technical supplementary information, 9 figures, comments are most welcom

Large Faraday rotation of resonant light in a cold atomic cloud

We experimentally studied the Faraday rotation of resonant light in an optically-thick cloud of laser-cooled rubidium atoms. Measurements yield a large Verdet constant in the range of 200 000 degrees/T/mm and a maximal polarization rotation of 150 degrees. A complete analysis of the polarization state of the transmitted light was necessary to account for the role of the probe laser's spectrum

Mapping water in protostellar outflows with Herschel: PACS and HIFI observations of L1448-C

We investigate on the spatial and velocity distribution of H2O along the L1448 outflow, its relationship with other tracers, and its abundance variations, using maps of the o-H2O 1_{10}-1_{01} and 2_{12}-1_{01} transitions taken with the Herschel-HIFI and PACS instruments, respectively. Water emission appears clumpy, with individual peaks corresponding to shock spots along the outflow. The bulk of the 557 GHz line is confined to radial velocities in the range \pm 10-50 km/s but extended emission associated with the L1448-C extreme high velocity (EHV) jet is also detected. The H2O 1_{10}-1_{01}/CO(3-2) ratio shows strong variations as a function of velocity that likely reflect different and changing physical conditions in the gas responsible for the emissions from the two species. In the EHV jet, a low H2O/SiO abundance ratio is inferred, that could indicate molecular formation from dust free gas directly ejected from the proto-stellar wind. We derive averaged Tkin and n(H2) values of about 300-500 K and 5 10^6 cm-3 respectively, while a water abundance with respect to H2 of the order of 0.5-1 10^{-6} along the outflow is estimated. The fairly constant conditions found all along the outflow implies that evolutionary effects on the timescales of outflow propagation do not play a major role in the H2O chemistry. The results of our analysis show that the bulk of the observed H2O lines comes from post-shocked regions where the gas, after being heated to high temperatures, has been already cooled down to a few hundred K. The relatively low derived abundances, however, call for some mechanism to diminish the H2O gas in the post-shock region. Among the possible scenarios, we favor H2O photodissociation, which requires the superposition of a low velocity non-dissociative shock with a fast dissociative shock able to produce a FUV field of sufficient strength.Comment: 16 pages, 13 figures, accepted for publication on Astronomy & Astrophysic

OH far-infrared emission from low- and intermediate-mass protostars surveyed with Herschel-PACS

OH is a key species in the water chemistry of star-forming regions, because its presence is tightly related to the formation and destruction of water. This paper presents OH observations from 23 low- and intermediate-mass young stellar objects obtained with the PACS integral field spectrometer on-board Herschel in the context of the Water In Star-forming Regions with Herschel (WISH) key program. Most low-mass sources have compact OH emission (< 5000 AU scale), whereas the OH lines in most intermediate-mass sources are extended over the whole PACS detector field-of-view (> 20000 AU). The strength of the OH emission is correlated with various source properties such as the bolometric luminosity and the envelope mass, but also with the OI and H2O emission. Rotational diagrams for sources with many OH lines show that the level populations of OH can be approximated by a Boltzmann distribution with an excitation temperature at around 70 K. Radiative transfer models of spherically symmetric envelopes cannot reproduce the OH emission fluxes nor their broad line widths, strongly suggesting an outflow origin. Slab excitation models indicate that the observed excitation temperature can either be reached if the OH molecules are exposed to a strong far-infrared continuum radiation field or if the gas temperature and density are sufficiently high. Using realistic source parameters and radiation fields, it is shown for the case of Ser SMM1 that radiative pumping plays an important role in transitions arising from upper level energies higher than 300 K. The compact emission in the low-mass sources and the required presence of a strong radiation field and/or a high density to excite the OH molecules points towards an origin in shocks in the inner envelope close to the protostar.Comment: Accepted for publication in Astronomy and Astrophysics. Abstract abridge