An expression for the water-sediment moving layer in unsteady flows valid for open channels and embankments

Abstract. During the floods, the effects of sediment transport in river beds are particulary significant and can be studied through the evolution of the water-sediment layer which moves in the lower part of a flow, named "moving layer". Moving layer variations along rivers lead to depositions and erosions and are typically unsteady, but are often tackled with expressions developed for steady (equilibrium) conditions. In this paper, we develop an expression for the moving layer in unsteady conditions and calibrate it with experimental data. During laboratory tests, we have in fact reproduced a rapidly changing unsteady flow by the erosion of a granular steep slope. Results have shown a clear tendency of the moving layer, for fixed discharges, toward equilibrium conditions. Knowing the equilibrium achievement has presented many difficulties, being influenced by the choice of the equilibrium expression and moreover by the estimation of the parameters involved (for example friction angle). Since we used only data relevant to hyper-concentrated mono-dimensional flows for the calibration – occurring for slope gradients in the range 0.03–0.20 – our model can be applied both on open channels and on embankments/dams, providing that the flows can be modelled as mono-dimensional, and that slopes and applied shear stress levels fall within the considered ranges

Trigonometric Parallaxes for 1,507 Nearby Mid-to-Late M-dwarfs

The MEarth survey is a search for small rocky planets around the smallest, nearest stars to the Sun as identified by high proper motion with red colors. We augmented our planetary search time series with lower cadence astrometric imaging and obtained two million images of approximately 1800 stars suspected to be mid-to-late M dwarfs. We fit an astrometric model to MEarth's images for 1507 stars and obtained trigonometric distance measurements to each star with an average precision of 5 milliarcseconds. Our measurements, combined with the 2MASS photometry, allowed us to obtain an absolute K_s magnitude for each star. In turn, this allows us to better estimate the stellar parameters than those obtained with photometric estimates alone and to better prioritize the targets chosen to monitor at high cadence for planetary transits. The MEarth sample is mostly complete out to a distance of 25 parsecs for stars of type M5.5V and earlier, and mostly complete for later type stars out to 20 parsecs. We find eight stars that are within ten parsecs of the Sun for which there did not exist a published trigonometric parallax distance estimate. We release with this work a catalog of the trigonometric parallax measurements for 1,507 mid-to-late M-dwarfs, as well as new estimates of their masses and radii.Comment: ApJ, accepted. 36 pages, 8 figures, 2 tables. Please find our data table here: http://www.cfa.harvard.edu/MEarth/DataDR2.htm

The Quantum Reverse Shannon Theorem based on One-Shot Information Theory

The Quantum Reverse Shannon Theorem states that any quantum channel can be simulated by an unlimited amount of shared entanglement and an amount of classical communication equal to the channel's entanglement assisted classical capacity. In this paper, we provide a new proof of this theorem, which has previously been proved by Bennett, Devetak, Harrow, Shor, and Winter. Our proof has a clear structure being based on two recent information-theoretic results: one-shot Quantum State Merging and the Post-Selection Technique for quantum channels.Comment: 30 pages, 4 figures, published versio

A Search for Additional Bodies in the GJ 1132 Planetary System from 21 Ground-based Transits and a 100 Hour Spitzer Campaign

We present the results of a search for additional bodies in the GJ 1132 system through two methods: photometric transits and transit timing variations of the known planet. We collected 21 transit observations of GJ 1132b with the MEarth-South array since 2015. We obtained 100 near-continuous hours of observations with the $Spitzer$ Space Telescope, including two transits of GJ 1132b and spanning 60\% of the orbital phase of the maximum period at which bodies coplanar with GJ 1132b would pass in front of the star. We exclude transits of additional Mars-sized bodies, such as a second planet or a moon, with a confidence of 99.7\%. When we combine the mass estimate of the star (obtained from its parallax and apparent $K_s$ band magnitude) with the stellar density inferred from our high-cadence $Spitzer$ light curve (assuming zero eccentricity), we measure the stellar radius of GJ 1132 to be $0.2105^{+0.0102}_{-0.0085} R_\odot$, and we refine the radius measurement of GJ 1132b to $1.130 \pm 0.056 R_\oplus$. Combined with HARPS RV measurements, we determine the density of GJ 1132b to be $6.2 \pm 2.0$\ g cm$^{-3}$, with the mass determination dominating this uncertainty. We refine the ephemeris of the system and find no evidence for transit timing variations, which would be expected if there was a second planet near an orbital resonance with GJ 1132b.Comment: 29 pages, 4 Tables, 8 Figures, Submitted to ApJ. Comments welcom

Partograph utilization and associated factors among obstetric care providers in North Shoa Zone, Central Ethiopia: a cross sectional study

Background: Globally, prolonged and obstructed labor contributed to 8% of maternal deaths which can be reduced by proper utilization of partograph during labor.Methods: An Institution based cross-sectional study was conducted in June, 2013 on 403 obstetric care providers. A pre-tested and structured questionnaire was used to collect data. Data was entered to EpiInfo version 3.5.1 statistical package and exported to SPSS version 20.0 for further analysis. Logistic regression analyses were used to see the association of different variables.Results: Out of 403 obstetric care providers, 40.2% utilized partograph during labor.Those who were midwives by profession were about 8 times more likely to have a consistent utilization of the partograph than general practitioners (AOR=8. 13, 95% CI: 2.67, 24.78). Similarly, getting on job training (AOR=2. 86, 95% CI: 1.69, 4.86), being knowledgeable on partograph (AOR=3. 79, 95% CI: 2.05, 7.03) and having favorable attitude towards partograph (AOR=2. 35, 95% CI: 1.14, 4.87) were positively associated with partograph utilization.Conclusion: Partograph utilization in labor monitoring was found to be low. Being a midwife by profession, on job training, knowledge and attitude of obstetric care providers were factors affecting partograph utilization. Providing on job training for providers would improve partograph utilization.Keywords: Ethiopia, obstetric care providers, partograp