Detection of broad 21-cm absorption at z = 0.656 in the complex sight-line towards 3C336

We report the detection of 21-cm absorption at z = 0.656 towards 1622+238 (3C336). The line is very broad with a Full-Width Half Maximum (FWHM) of 235 km/s, giving a velocity integrated optical depth of 2.2 km/s. The centroid of the line is offset from that of the known damped Lyman-alpha absorption (DLA) system by 50 km/s, and if the Lyman-alpha and 21-cm absorption are due to the same gas, we derive a spin temperature of < 60 K, which would be the lowest yet in a DLA. The wide profile, which is over four times wider than that of any other DLA, supports the hypothesis that the hydrogen absorption is occurring either in the disk of a large underluminous spiral or a group of dim unidentified galaxies, associated with the single object which has been optically identified at this redshift.Comment: 5 pages, 3 figures, accepted by MNRAS Letter

Electrophysiological correlates of high-level perception during spatial navigation

We studied the electrophysiological basis of object recognition by recording scalp\ud electroencephalograms while participants played a virtual-reality taxi driver game.\ud Participants searched for passengers and stores during virtual navigation in simulated\ud towns. We compared oscillatory brain activity in response to store views that were targets or\ud nontargets (during store search) or neutral (during passenger search). Even though store\ud category was solely defined by task context (rather than by sensory cues), frontal ...\ud \u

Quantum Symmetries and Strong Haagerup Inequalities

In this paper, we consider families of operators $\{x_r\}_{r \in \Lambda}$ in a tracial C$^\ast$-probability space $(\mathcal A, \phi)$, whose joint $\ast$-distribution is invariant under free complexification and the action of the hyperoctahedral quantum groups $\{H_n^+\}_{n \in \N}$. We prove a strong form of Haagerup's inequality for the non-self-adjoint operator algebra $\mathcal B$ generated by $\{x_r\}_{r \in \Lambda}$, which generalizes the strong Haagerup inequalities for $\ast$-free R-diagonal families obtained by Kemp-Speicher \cite{KeSp}. As an application of our result, we show that $\mathcal B$ always has the metric approximation property (MAP). We also apply our techniques to study the reduced C$^\ast$-algebra of the free unitary quantum group $U_n^+$. We show that the non-self-adjoint subalgebra $\mathcal B_n$ generated by the matrix elements of the fundamental corepresentation of $U_n^+$ has the MAP. Additionally, we prove a strong Haagerup inequality for $\mathcal B_n$, which improves on the estimates given by Vergnioux's property RD \cite{Ve}

Electron-impact ionization of atomic hydrogen at 2 eV above threshold

The convergent close-coupling method is applied to the calculation of fully differential cross sections for ionization of atomic hydrogen by 15.6 eV electrons. We find that even at this low energy the method is able to yield predictive results with small uncertainty. As a consequence we suspect that the experimental normalization at this energy is approximately a factor of two too high.Comment: 10 page

Trends in aerosol abundances and distributions

The properties of aerosols that reside in the upper atmosphere are described. Special emphasis is given to the influence these aerosols have on ozone observation systems, mainly through radiative effects, and on ambient ozone concentrations, mainly through chemical effects. It has long been appreciated that stratospheric particles can interfere with the remote sensing of ozone distribution. The mechanism and magnitude of this interference are evaluated. Separate sections deal with the optical properties of upper atmospheric aerosols, long-term trends in stratospheric aerosols, perturbations of the stratospheric aerosol layer by volcanic eruptions, and estimates of the impacts that such particles have on remotely measured ozone concentrations. Another section is devoted to a discussion of the polar stratospheric clouds (PSC's). These unique clouds, recently discovered by satellite observation, are now thought to be intimately connected with the Antarctic ozone hole. Accordingly, interest in PSC's has grown considerably in recent years. This chapter describes what we know about the morphology, physical chemistry, and microphysics of PSC's

Mapping ammonia risk on sensitive habitats in Ireland

© 2018 Elsevier B.V. The aim of this study was to provide a simple, cost-effective, risk-based map of terrestrial areas in Ireland where environmental quality may be at risk from atmospheric ammonia. This risk-based approach identifies Natura 2000 sites in Ireland at risk from agricultural atmospheric ammonia, collating best available data using Geographical Information Systems (GIS). In mapping ammonia risk on sensitive habitats (MARSH), the method identifies sources of ammonia, classifying them on a scale of risk from 0 to 5. These sources are subsequently summed based on a weighting determined by their contribution to national emissions divided by their potentially impacted area. A Pearson's correlation coefficient of 0.72 allows for concentrations from United Kingdom's FRAME modelling to be applied to the MARSH model, which are corrected based on recent monitoring. Applying Designation Weighted Indicators (DWI), the MARSH model predicts that 80.7, 34.3 and 5.9% of Natura 2000 sites in Ireland may exceed ambient concentrations of 1, 2, and 3 μg/m3, respectively. A Nitroindex map of Ireland based on available lichen records was also developed and is presented as part of this study. This Nitroindex was used to identify areas where impacts have already been recorded, thus informing the classification of sites “at-risk”. The combination of both the MARSH and Nitroindex models ascertains which Natura 2000 sites are most at risk, thereby providing valuable data to relevant authorities. The MARSH model acts as a first step towards screening and assessing Natura 2000 sites most at risk from atmospheric ammonia, providing a tool to demonstrate compliance with the National Emissions Ceilings Directive

ERS-2 SAR soil moisture and herbaceous biomass monitoring across a semi-arid transect in Israel

Relationships between radar backscattering coefficient (σº) and environmental parameters of volumetric soil moisture and biomass were empirically investigated in two sites. These sites represent an annual rainfall change from 450 mm to 250 mm across a semiarid transition zone between Mediterranean and arid environments in Israel. A strong linear correlation was found between ground measurements of volumetric soil moisture taken place at the two sites in three different dates and corresponding radar backscatter intensities measured from ERS-2 SAR images. The slope and intercept values of the regression equation are similar to those reported in other regions of the world. Relationships between the radar backscatter and Herbaceous biomass were examined in areas of homogenous vegetation cover. Results show strong linear correlation between Herbaceous biomass measured in the field and the ERS-2 backscatter