Cool carbon stars in the halo and in dwarf galaxies: Halpha, colours, and variabiity

The population of cool carbon (C) stars located far from the galactic plane is probably made of debris of small galaxies such as the Sagittarius dwarf spheroidal galaxy (Sgr), which are disrupted by the gravitational field of the Galaxy. We aim to know this population better through spectroscopy, 2MASS photometric colours, and variability data. When possible, we compared the halo results to C star populations in the Fornax dwarf spheroidal galaxy, Sgr, and the solar neighbourhood. We first present a few new discoveries of C stars in the halo and in Fornax. The number of spectra of halo C stars is now 125. Forty percent show Halpha in emission. The narrow location in the JHK diagram of the halo C stars is found to differ from that of similar C stars in the above galaxies. The light curves of the Catalina and LINEAR variability databases were exploited to derive the pulsation periods of 66 halo C stars. A few supplementary periods were obtained with the TAROT telescopes. We confirm that the period distribution of the halo strongly resembles that of Fornax, and we found that is it very different from the C stars in the solar neighbourhood. There is a larger proportion of short period Mira/SRa variables in the halo than in Sgr, but the survey for C stars in this dwarf galaxy is not complete, and the study of their variability needs to be continued to investigate the link between Sgr and the cool halo C stars.Comment: 11 pages, 10 figures + one appendix of 26 pages; accepted for publication in Astronomy and Astrophysic

Aquifères karstiques et caractéristiques physico-chimiques des eaux à l'étiage : exemple de la zone tropicale de l'hémisphère sud (Madagascar)

Deux karsts de la zone tropicale actuelle de l'hémisphère sud (Madagascar), sont tout d'abord analysés sur le plan géomorphologique. Les facteurs lithologiques, structuraux et climatiques confèrent à ces karsts des évolutions et des fonctionnements actuels nettement différenciés entre eux. Dans un deuxième temps, les caractéristiques hydrochimiques des eaux à l'étiage sont examinées et comparées à celles d'un karst de la zone tempérée (bordure méditerranéenne). De cette comparaison, il ressort que les eaux karstiques présentent des caractéristiques physico-chimiques à l'étiage très voisines quelle que soit la latitude. Par exemple, toutes les eaux sont sous-saturées en carbonates, sauf si la nappe est captive. Enfin, il est mis l'accent en conclusion sur le fait que les conditions climatiques propices à la karstification et à un haut degré d'évolution ne s'expriment pleinement que si des évènements tectoniques interviennent au cours des phénomènes de dissolution. Les morphologies karstiques hautement évoluées, comme celles de Madagascar, résultent ainsi d'une étroite complémentarité entre facteurs lithologiques, structuraux et climatiques. (Résumé d'auteur

A new spice-like modeling tool for bio- and electro- acoustic systems including thermoviscous effects

International audienceA dedicated toolbox has been developed within ASYGN a recent software tool that simulates aVLSI circuits at a high-level of modeling. It accounts in both time- and frequency- domain for the specific feature of bio- and electro- acoustic systems especially when some of the constituting elements are very thin or narrow. The models correspond to systems of complex equations in which some of the complex coefficients can be frequency dependent. Results are solved and viewed in real time. The tool was developed to introduce some improvement in the model of the auditory system of the cricket. In 2007 Reeve et al. designed and tested an electrical equivalent circuit based on Michelsen 1994. The latter results from two major simplification namely the absence of thermoviscous effects and of any acoustical role of a septum located in the middle of a transverse acoustic trachea. Thanks to the weak couplings the model can be subdivided into independent elements such as tubes, cavities or membranes simply connected together. Thermoviscous effects and the role of the medial septum can now be fully investigated. Our results were first validated using Matlab. Our model reveals interesting feature compared to its historical counterpart

Ventromedial medulla inhibitory neuron inactivation induces REM sleep without atonia and REM sleep behavior disorder

Despite decades of research, there is a persistent debate regarding the localization of GABA/glycine neurons responsible for hyperpolarizing somatic motoneurons during paradoxical (or REM) sleep (PS), resulting in the loss of muscle tone during this sleep state. Combining complementary neuroanatomical approaches in rats, we first show that these inhibitory neurons are localized within the ventromedial medulla (vmM) rather than within the spinal cord. We then demonstrate their functional role in PS expression through local injections of adeno-associated virus carrying specific short-hairpin RNA in order to chronically impair inhibitory neurotransmission from vmM. After such selective genetic inactivation, rats display PS without atonia associated with abnormal and violent motor activity, concomitant with a small reduction of daily PS quantity. These symptoms closely mimic human REM sleep behavior disorder (RBD), a prodromal parasomnia of synucleinopathies. Our findings demonstrate the crucial role of GABA/glycine inhibitory vmM neurons in muscle atonia during PS and highlight a candidate brain region that can be susceptible to α-synuclein-dependent degeneration in RBD patients

Business exit and strategic change: Sticking to the knitting or striking a new strategic path?

The purpose of this study is to examine the potential of business exit for initiating strategic change in divesting parent firms. In contrast to prior literature that mainly investigates the impact of different antecedents on the likelihood of business exit in general, this study additionally tests the influence of these antecedents on the choice between two exit types with a cross-industry sample of divesting firms listed in the German CDAX over the time period 1999-2004. A divestiture involving strategic change is a strategic business exit; otherwise it is denoted as status quo-preserving. The findings reveal that a relatively highly dissipated focus does not automatically enhance the likelihood of business exit in general and status quo-preserving business exit in particular. CEO turnover and pressures exerted by institutional investors predict neither strategic nor status quo-preserving business exit. Low firm performance does not nurture the likelihood of business exit per se but especially promotes status quo-preserving business exit

Student Support: A K-6 At-risk Program Model

The purpose of this study was to identify priority components and measurement standards of an effective K-6 At-Risk Program, then develop a resource guide for At-Risk program managers. A survey was sent to the Washington school districts with at-risk programs in place, as identified by the Student Retention and Retrieval Program handbook issued by the Office of the Superintendent of Public Instruction. The survey was successful in helping identify the most effective program components: individual and small group counseling, classroom presentations with published materials, parent education, attendance monitoring, and peer/adult tutors. Evaluation standards vary according to program components and generally rely on feedback from staff, parents, and students. The result of the study was a handbook titled, Student Support: A K-6 At-Risk Program Model

Depth-bounded Epistemic Logic

Epistemic logics model how agents reason about their beliefs and the beliefs of other agents. Existing logics typically assume the ability of agents to reason perfectly about propositions of unbounded modal depth. We present DBEL, an extension of S5 that models agents that can reason about epistemic formulas only up to a specific modal depth. To support explicit reasoning about agent depths, DBEL includes depth atoms Ead (agent a has depth exactly d) and Pad (agent a has depth at least d). We provide a sound and complete axiomatization of DBEL. We extend DBEL to support public announcements for bounded depth agents and show how the resulting DPAL logic generalizes standard axioms from public announcement logic. We present two alternate extensions and identify two undesirable properties, amnesia and knowledge leakage, that these extensions have but DPAL does not. We provide axiomatizations of these logics as well as complexity results for satisfiability and model checking. Finally, we use these logics to illustrate how agents with bounded modal depth reason in the classical muddy children problem, including upper and lower bounds on the depth knowledge necessary for agents to successfully solve the problem.Comment: In Proceedings TARK 2023, arXiv:2307.0400

A search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology at sqrt(s) = 1.96 TeV

We report a search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology, using an integrated luminosity of 0.93 inverse femtobarn recorded by the D0 detector at the Fermilab Tevatron Collider. The analysis includes signal contributions from pp->ZH->nu nu b b, as well as from WH production in which the charged lepton from the W boson decay is undetected. Neural networks are used to separate signal from background. In the absence of a signal, we set limits on the cross section of pp->VH times the branching ratio of H->bb at the 95% C.L. of 2.6 - 2.3 pb, for Higgs boson masses in the range 105 - 135 GeV, where V=W,Z. The corresponding expected limits range from 2.8 pb - 2.0 pb.Comment: Submitted to Phys. Rev. Letter

Observation of ZZ production in ppbar collisions at sqrt(s) = 1.96 TeV

We present an observation for ZZ -> l+l-l'+l'- (l, l' = e or mu) production in ppbar collisions at a center-of-mass energy of sqrt(s) = 1.96 TeV. Using 1.7 fb-1 of data collected by the D0 experiment at the Fermilab Tevatron Collider, we observe three candidate events with an expected background of 0.14 +0.03 -0.02 events. The significance of this observation is 5.3 standard deviations. The combination of D0 results in this channel, as well as in ZZ -> l+l-nunubar, yields a significance of 5.7 standard deviations and a combined cross section of sigma(ZZ) = 1.60 +/- 0.63 (stat.) +0.16 -0.17 (syst.) pb.Comment: 7 pages, 1 figure, 2 tables Modified slightly following review proces

Measurement of the W boson mass

We present a measurement of the W boson mass in W -> ev decays using 1 fb^-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W -> ev candidate events, we measure M_W = 80.401 +- 0.043 GeV. This is the most precise measurement from a single experiment.Comment: As published in PR