Measurements of the effect of horizontal variability of atmospheric backscatter on dial measurements

The horizontal variability of atmospheric backscatter may have a substantial effect on how Differential Absorption Lidar (DIAL) data must be taken and analyzed. To minimize errors, lidar pulse pairs are taken with time separations which are short compared to the time scales associated with variations in atmospheric backscatter. To assess the atmospheric variability for time scales which are long compared to the lidar pulse repetition rate, the variance of the lidar return signal in a given channel can be computed. The variances of the on-line, off-line, and ration of the on-line to off-line signals at given altitudes obtained with the dual solid-state Alexandrite laser system were calculated. These evaluations were made for both down-looking aircraft and up-looking ground-based lidar data. Data were taken with 200 microsecond separation between on-line and off-line laser pulses, 30 m altitude resolution, 5 Hz repetition rate, and the signal were normalized for outgoing laser energy

Homotheties and topology of tangent sphere bundles

We prove a Theorem on homotheties between two given tangent sphere bundles $S_rM$ of a Riemannian manifold $M,g$ of $\dim\geq 3$, assuming different variable radius functions $r$ and weighted Sasaki metrics induced by the conformal class of $g$. New examples are shown of manifolds with constant positive or with constant negative scalar curvature, which are not Einstein. Recalling results on the associated almost complex structure $I^G$ and symplectic structure ${\omega}^G$ on the manifold $TM$, generalizing the well-known structure of Sasaki by admitting weights and connections with torsion, we compute the Chern and the Stiefel-Whitney characteristic classes of the manifolds $TM$ and $S_rM$.Comment: 15 pages, to appear in Journal of Geometr

Католицька концепція міжрелігійного діалогу: зміна акцентів

In Arabidopsis roots, the transcription factor MYB72 plays a dual role in the onset of rhizobacteria-induced systemic resistance (ISR) and plant survival under conditions of limited iron availability. Previously, it was shown that MYB72 coordinates the expression of a gene module that promotes synthesis and excretion of iron-mobilizing phenolic compounds in the rhizosphere, a process involved in both iron acquisition and ISR signaling. Here, we show that volatile compounds (VOCs) from ISR-inducing Pseudomonas bacteria are important elicitors of MYB72. VOCs-induced MYB72 is co-expressed with the iron uptake-related genes FERRIC REDUCTION OXIDASE 2 (FRO2) and IRON-REGULATED TRANSPORTER 1 (IRT1) in a FER-LIKE IRON DEFICIENCY INDUCED TRANSCRIPTION FACTOR (FIT)-dependent manner, indicating that MYB72 is an intrinsic part of the plants’ iron acquisition response that is typically activated upon iron starvation. However, VOCs-induced MYB72 is activated independently of the iron availability in the root vicinity. Moreover, rhizobacterial VOCs-mediated induction of MYB72 requires photosynthesis-related signals, while iron deficiency in the rhizosphere can activate MYB72 in the absence of shoot-derived signals. Together, these results show that the ISR- and iron acquisition-related transcription factor MYB72 in Arabidopsis roots is activated by rhizobacterial volatiles and photosynthesis-related signals, and can enhance the iron acquisition capacity of roots independently of the iron availability in the rhizosphere. This work highlights the role of MYB72 in plant processes by which root microbiota simultaneously stimulate systemic immunity and activate the iron uptake machinery in their host plants

Equilibrium of sinks and sources of sulphate over Europe: comparison between a six-year simulation and EMEP observations

Sulphate distributions were simulated with a global chemistry transport model. A chemical scheme describing the sulphur cycle and the parameterisations of the main sinks for sulphate aerosols were included in the model. A six-year simulation was conducted from the years 2000 to 2005, driven by the ECMWF operational analyses. Emissions come from an inventory representative of the year 2000. This paper focuses on the analysis of the sulphate sinks and sources over Europe for the entire period of simulation. The Sulphate burden shows a marked annual cycle, which is the result of the annual variations of the aqueous and gaseous chemistry. Regionally, the monthly mean aerosol burden can vary by a factor of 2 from one year to another, because of different weather conditions, driving chemistry, transport and wet deposition of sulphate aerosols. Sulphate ground concentrations, scavenging fluxes and precipitation modelled were compared with observations. The model represents quite well sulphate fields over Europe, but has a general tendency to overestimate sulphate ground concentrations, in particular over Northern Europe. We assume that it is linked to the representation of the scavenging fluxes, which are underestimated. We suggest that uncertainties in modelled precipitation explain only partially the underestimation of the scavenging fluxes in the model

Large tunable valley splitting in edge-free graphene quantum dots on boron nitride

Coherent manipulation of binary degrees of freedom is at the heart of modern quantum technologies. Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been demonstrated in many solid state systems, while exploitation of the valley has only recently been started, yet without control on the single electron level. Here, we show that van-der Waals stacking of graphene onto hexagonal boron nitride offers a natural platform for valley control. We use a graphene quantum dot induced by the tip of a scanning tunneling microscope and demonstrate valley splitting that is tunable from -5 to +10 meV (including valley inversion) by sub-10-nm displacements of the quantum dot position. This boosts the range of controlled valley splitting by about one order of magnitude. The tunable inversion of spin and valley states should enable coherent superposition of these degrees of freedom as a first step towards graphene-based qubits

Nonintegrability of the two-body problem in constant curvature spaces

We consider the reduced two-body problem with the Newton and the oscillator potentials on the sphere ${\bf S}^{2}$ and the hyperbolic plane ${\bf H}^{2}$. For both types of interaction we prove the nonexistence of an additional meromorphic integral for the complexified dynamic systems.Comment: 20 pages, typos correcte

Observation of Two Narrow States Decaying into Ξc+γ\Xi_{c}^{+}\gamma and Ξc0γ\Xi_{c}^{0}\gamma

We report the first observation of two narrow charmed strange baryons decaying to $\Xi_c^+\gamma$ and $\Xi_c^0\gamma$, respectively, using data from the CLEO II detector at CESR. We interpret the observed signals as the $\Xi_c^{+\prime}(c{su})$ and $\Xi_c^{0\prime}(c{sd})$, the symmetric partners of the well-established antisymmetric $\Xi_c^+(c[su])$ and $\Xi_c^0(c[sd])$. The mass differences $M(\Xi_c^{+\prime})-M(\Xi_c^+)$ and $M(\Xi_c^{0\prime})-M(\Xi_c^0)$ are measured to be $107.8\pm 1.7\pm 2.5$ and $107.0\pm 1.4\pm 2.5 MeV/c^2$, respectively.Comment: 11 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Improved Measurement of the Pseudoscalar Decay Constant fDsf_{D_{s}}

We present a new determination of the Ds decay constant, f_{Ds} using 5 million continuum charm events obtained with the CLEO II detector. Our value is derived from our new measured ratio of widths for Ds -> mu nu/Ds -> phi pi of 0.173+/- 0.021 +/- 0.031. Taking the branching ratio for Ds -> phi pi as (3.6 +/- 0.9)% from the PDG, we extract f_{Ds} = (280 +/- 17 +/- 25 +/- 34){MeV}. We compare this result with various model calculations.Comment: 23 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

How acceptable are antiretrovirals for the prevention of sexually transmitted HIV? A review of research on the acceptability of oral pre-exposure prophylaxis and treatment as prevention

Recent research has demonstrated how antiretrovirals (ARVs) could be effective in the prevention of sexually transmitted HIV. We review research on the acceptability of oral pre-exposure prophylaxis (PrEP) and treatment as prevention (TasP) for HIV prevention amongst potential users. We consider with whom, where and in what context this research has been conducted, how acceptability has been approached, and what research gaps remain. Findings from 33 studies show a lack of TasP research, PrEP studies which have focused largely on men who have sex with men (MSM) in a US context, and varied measures of acceptability. In order to identify when, where and for whom PrEP and TasP would be most appropriate and effective, research is needed in five areas: acceptability of TasP to people living with HIV; motivation for PrEP use and adherence; current perceptions and management of risk; the impact of broader social and structural factors; and consistent definition and operationalisation of acceptability which moves beyond adherence