5,838 research outputs found
The Holevo-Schumacher-Westmoreland Channel Capacity for a Class of Qudit Unital Channels
The Holevo-Schumacher-Westmoreland (HSW) classical (entanglement-unassisted)
channel capacity for a class of qudit unital channels is shown to be C =
log2(d) - Smin, where d is the dimension of the qudit, and Smin is the minimum
possible von Neumann entropy at the channel output. The HSW channel capacity
for tensor products of this class of unital qudit channels is shown to obey the
same formula.Comment: 21 Pages. No Figure
Measurement of the Î hyperon lifetime
A new, more precise measurement of the Lambda hyperon lifetime is performed using a large data sample of Pb-Pb collisions at root s(NN) = 5.02 TeV with ALICE. The Lambda and (Lambda)_bar hyperons are reconstructed at midrapidity using their two-body weak decay channel Lambda -> p + pi(-) and (Lambda)_bar -> (p )_bar + pi(+). The measured value of the Lambda lifetime is tau(Lambda) = [261.07 +/- 0.37(stat.) +/- 0.72o(syst)] ps. The relative difference between the lifetime of Lambda and (Lambda)_bar, which represents an important test of CPT invariance in the strangeness sector, is also measured. The obtained value (tau(Lambda) - tau((Lambda)_bar))/tau(Lambda) = (0.0013 +/- 0.0028(stat.) +/- 0.0021(syst.) is consistent with zero within the uncertainties. Both measurements of the. hyperon lifetime and of the relative difference between tau(Lambda) and tau((Lambda)_bar) are in agreement with the corresponding world averages of the Particle Data Group and about a factor of three more precise
Constraining the ages of the fireballs in the wake of the dIrr galaxy VCC1217 / IC3418
A complex of Halpha emitting blobs with strong FUV excess is associated to
the dIrr galaxy VCC1217 / IC3418 (Hester et al. 2010), and extends up to 17 Kpc
in the South-East direction. These outstanding features can be morphologically
divided into diffuse filaments and compact knots, where most of the star
formation activity traced by Halpha takes place. We investigate the properties
of the galaxy and the blobs using a multiwavelength approach in order to
constrain their origin. We collect publicly available data in UV and Halpha and
observe the scene in the optical U,g,r,i bands with LBT. The photometric data
allows to evaluate the star formation rate and to perform a SED fitting
separately of the galaxy and the blobs in order to constrain their stellar
population age. Moreover we analyze the color and luminosity profile of the
galaxy and its spectrum to investigate its recent interaction with the Virgo
cluster. Our analysis confirms that the most plausible mechanism for the
formation of the blobs is ram pressure stripping by the Virgo cluster IGM. The
galaxy colors, luminosity profile and SED are consistent with a sudden gas
depletion in the last few hundred Myr. The SED fitting of the blobs constrains
their ages in < 400 Myr.Comment: 10 pages, 11 figures, accepted for publication in Astronomy and
Astrophysic
New technologies to improve root canal disinfection
Effective irrigant delivery and agitation are prerequisites to promote root canal disinfection and debris removal and improve successful endodontic treatment. This paper presents an overview of the currently available technologies to improve the cleaning of the endodontic space and their debridement efficacy. A PubMed electronic search was conducted with appropriate key words to identify the relevant literature on this topic. After retrieving the full-text articles, all the articles were reviewed and the most appropriate were included in this review. Several different systems of mechanical activation of irrigants to improve endodontic disinfection were analysed: manual agitation with gutta-percha cones, endodontic instruments or special brushes, vibrating systems activated by low-speed hand-pieces or by sonic or subsonic energy, use of ultrasonic or laser energy to mechanically activate the irrigants and apical negative pressure irrigation systems. Furthermore, this review aims to describe systems designed to improve the intracanal bacterial decontamination by a specific chemical action, such as ozone, direct laser action or light-activated disinfection. The ultrasonic activation of root canal irrigants and of sodium hypochlorite in particular still remains the gold standard to which all other systems of mechanical agitation analyzed in this article were compared. From this overview, it is evident that the use of different irrigation systems can provide several advantages in the clinical endodontic outcome and that integration of new technologies, coupled with enhanced techniques and materials, may help everyday clinical practice
The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). II. Constraints on star formation in ram-pressure stripped gas
Context: Several galaxies in the Virgo cluster are known to have large HI gas
tails related to a recent ram-pressure stripping event. The Virgo cluster has
been extensively observed at 1539 A in the far-ultraviolet for the GALEX
Ultraviolet Virgo Cluster Survey (GUViCS), and in the optical for the Next
Generation Virgo Survey (NGVS), allowing a study of the stellar emission
potentially associated with the gas tails of 8 cluster members. On the
theoretical side, models of ram-pressure stripping events have started to
include the physics of star formation. Aim: We aim to provide quantitative
constraints on the amount of star formation taking place in the ram-pressure
stripped gas, mainly on the basis of the far-UV emission found in the GUViCS
images in relation with the gas content of the tails. Methods: We have
performed three comparisons of the young stars emission with the gas column
density: visual, pixel-by-pixel and global. We have compared our results to
other observational and theoretical studies. Results: We find that the level of
star formation taking place in the gas stripped from galaxies by ram-pressure
is low with respect to the available amount of gas. Star formation is lower by
at least a factor 10 compared to the predictions of the Schmidt Law as
determined in regular spiral galaxy disks. It is also lower than measured in
dwarfs galaxies and the outer regions of spirals, and than predicted by some
numerical simulations. We provide constraints on the star formation efficiency
in the ram-pressure stripped gas tails, and compare these with current models.Comment: Accepted in A&A, 17 pages (including the appendix and "on-line"
figures of the paper
Advances on Testing C-Planarity of Embedded Flat Clustered Graphs
We show a polynomial-time algorithm for testing c-planarity of embedded flat
clustered graphs with at most two vertices per cluster on each face.Comment: Accepted at GD '1
When a leader job resource can be ambivalent or even destructive: Independence at work as a double-edged sword
<div><p>Independence at work is commonly considered a job resource which fosters motivation and employee well-being. Somewhat paradoxically, it is embedded in a relationship, and employeesâ independence also hinges on their leadersâ willingness to grant it. Analyzing this resource as part of the leader-follower relationship can be useful in exploring its beneficial, ambivalent, or detrimental reciprocal effects. We present two Actor-Partner Interdependence Models (APIM) which analyze leadersâ and followersâ independence as antecedents, and work engagement and emotional exhaustion as outcomes. We test our models on 112 pairs of UK workers, finding a significant partner effect between leadersâ independence and followersâ exhaustion. Our findings confirm the utility of a dyadic perspective for investigating leadership and well-being at work, and suggest improvements for leadership training and measures fostering job well-being.</p></div
Recommended from our members
Parkinsonâs disease-linked Parkin mutations impair glutamatergic signaling in hippocampal neurons
Background
Parkinsonâs disease (PD)-associated E3 ubiquitin ligase Parkin is enriched at glutamatergic synapses, where it ubiquitinates multiple substrates, suggesting that its mutation/loss-of-function could contribute to the etiology of PD by disrupting excitatory neurotransmission. Here, we evaluate the impact of four common PD-associated Parkin point mutations (T240M, R275W, R334C, G430D) on glutamatergic synaptic function in hippocampal neurons.
Results
We find that expression of these point mutants in cultured hippocampal neurons from Parkin-deficient and Parkin-null backgrounds alters NMDA and AMPA receptor-mediated currents and cell-surface levels and prevents the induction of long-term depression. Mechanistically, we demonstrate that Parkin regulates NMDA receptor trafficking through its ubiquitination of GluN1, and that all four mutants are impaired in this ubiquitinating activity. Furthermore, Parkin regulates synaptic AMPA receptor trafficking via its binding and retention of the postsynaptic scaffold Homer1, and all mutants are similarly impaired in this capacity.
Conclusion
Our findings demonstrate that pathogenic Parkin mutations disrupt glutamatergic synaptic transmission in hippocampal neurons by impeding NMDA and AMPA receptor trafficking. Such effects may contribute to the pathophysiology of PD in PARK2 patients
Computing NodeTrix Representations of Clustered Graphs
NodeTrix representations are a popular way to visualize clustered graphs;
they represent clusters as adjacency matrices and inter-cluster edges as curves
connecting the matrix boundaries. We study the complexity of constructing
NodeTrix representations focusing on planarity testing problems, and we show
several NP-completeness results and some polynomial-time algorithms. Building
on such algorithms we develop a JavaScript library for NodeTrix representations
aimed at reducing the crossings between edges incident to the same matrix.Comment: Appears in the Proceedings of the 24th International Symposium on
Graph Drawing and Network Visualization (GD 2016
Molecular gas dominated 50 kpc ram pressure stripped tail of the Coma galaxy D100
We have discovered large amounts of molecular gas, as traced by CO emission, in the ram pressure stripped gas tail of the Coma cluster galaxy D100 (GMP 2910), out to large distances of about 50 kpc. D100 has a 60 kpc long, strikingly narrow tail which is bright in X-rays and H{\alpha}. Our observations with the IRAM 30m telescope reveal in total ~ 10^9 M_sun of H_2 (assuming the standard CO-to-H_2 conversion) in several regions along the tail, thus indicating that molecular gas may dominate its mass. Along the tail we measure a smooth gradient in the radial velocity of the CO emission that is offset to lower values from the more diffuse H{\alpha} gas velocities. Such a dynamic separation of phases may be due to their differential acceleration by ram pressure. D100 is likely being stripped at a high orbital velocity >2200 km/s by (nearly) peak ram pressure. Combined effects of ICM viscosity and magnetic fields may be important for the evolution of the stripped ISM. We propose D100 has reached a continuous mode of stripping of dense gas remaining in its nuclear region. D100 is the second known case of an abundant molecular stripped-gas tail, suggesting that conditions in the ICM at the centers of galaxy clusters may be favorable for molecularization. From comparison with other galaxies, we find there is a good correlation between the CO flux and the H{\alpha} surface brightness in ram pressure stripped gas tails, over about 2 dex
- âŠ