A Small Interstellar Probe to the Heliospheric Boundary and Interstellar Space

The Small Interstellar Probe m1ss1on would be designed to cross the solar wind termination shock and the heliopause, and make a significant penetration into nearby interstellar space. The principal scientific objectives of this mission would be to explore the structure of the heliosphere, to investigate its interaction with the interstellar medium, and to explore the nature of the interstellar medium itself. These studies would be carried out by a ~200 kg spacecraft carrying a scientific payload designed to make comprehensive, in situ measurements of both heliospheric and interstellar plasma, fields, energetic particles, gas, and dust. New trajectory calculations indicate significantly improved performance over earlier studies with larger spacecraft, including spacecraft velocities ranging from -6 to -14 AU/yr., depending on trajectory and launch vehicle

Investigation of the reactivity of AlCl3 and CoCl2 toward molten alkali-metal nitrates in order to synthesize CoAl2O4

Cobalt aluminate CoAl2O4 powder, constituted of nano-sized crystallites, is prepared, involving the reactivity of AlCl3 and CoCl2 with molten alkali-metal nitrates. The reaction at 450 °C for 2 h leads to a mixture of spinel oxide Co3O4 and amorphous γ-Al2O3. It is transformed into the spinel oxide CoAl2O4 by heating at 1000 °C. The powders are mainly characterized by XRD, FTIR, ICP, electron microscopy and diffraction, X-EDS and diffuse reflection. Their properties are compared to those of powders obtained by solid state reactions of a mechanical mixture of chlorides or oxides submitted to the same thermal treatment

Importance of quantum tunneling in vacancy-hydrogen complexes in diamond

Our ab initio calculations of the hyperfine parameters for negatively charged vacancy-hydrogen and nitrogen-vacancy-hydrogen complexes in diamond compare static defect models and models which account for the quantum tunneling behavior of hydrogen. The static models give rise to hyperfine splittings that are inconsistent with the experimental electron paramagnetic resonance data. In contrast, the hyperfine parameters for the quantum dynamical models are in agreement with the experimental observations. We show that the quantum motion of the proton is crucial to the prediction of symmetry and hyperfine constants for two simple defect centers in diamond. Static a priori methods fail for these systems

Influence of the wintertime North Atlantic Oscillation on European tropospheric composition: an observational and modelling study

We have used satellite observations and a simulation from the TOMCAT chemistry transport model (CTM) to investigate the influence of the well-known wintertime North Atlantic Oscillation (NAO) on European tropospheric composition. Under the positive phase of the NAO (NAO-high), strong westerlies tend to enhance transport of European pollution (e.g. nitrogen oxides, NOx; carbon monoxide, CO) away from anthropogenic source regions. In contrast, during the negative phase of the NAO (NAO-low), more stable meteorological conditions lead to a build-up of pollutants over these regions relative to the wintertime average pollution levels. However, the secondary pollutant ozone shows the opposite signal of larger values during NAO-high. NAO-high introduces Atlantic ozone-enriched air into Europe, while under NAO-low westerly transport of ozone is reduced, yielding lower values over Europe. Furthermore, ozone concentrations are also decreased by chemical loss through the reaction with accumulated primary pollutants such as nitric oxide (NO) in NAO-low. Peroxyacetyl nitrate (PAN) in the upper troposphere–lower stratosphere (UTLS) peaks over Iceland and southern Greenland in NAO-low, between 200 and 100 hPa, consistent with the trapping by an anticyclone at this altitude. Model simulations show that enhanced PAN over Iceland and southern Greenland in NAO-low is associated with vertical transport of polluted air from the mid-troposphere into the UTLS. Overall, this work shows that NAO circulation patterns are an important governing factor for European wintertime composition and air pollution

Ionic adsorption on the brucite (0001) surface:a periodic electrostatic embedded cluster method study

Density functional theory (DFT) at the generalised gradient approximation level is employed within the periodic electrostatic embedded cluster method (PEECM) to model the brucite (0001) surface. Three representative studies are then used to demonstrate the reliability of the PEECM for the description of the interactions of various ionic species with the layered Mg(OH)2 structure, and its performance is compared with periodic DFT, an approach known to be challenging for the adsorption of charged species. The adsorption energies of a series of s block cations, including Sr2+ and Cs+ which are known to coexist with brucite in nuclear waste storage ponds, are well described by the embedded cluster model, provided that basis sets of triple-zeta quality are employed for the adsorbates. The substitution energies of Ca2+ and Sr2+ into brucite obtained with the PEECM are very similar to periodic DFT results, and comparison of the approaches indicates that two brucite layers in the quantum mechanical part of the PEECM are sufficient to describe the substitution. Finally, a detailed comparison of the periodic and PEECM DFT approaches to the energetic and geometric properties of differently coordinated Sr[(OH)2(H2O)4] complexes on brucite shows an excellent agreement in adsorption energies, Sr–O distances, and bond critical point electron densities (obtained via the quantum theory of atoms-in-molecules), demonstrating that the PEECM can be a useful alternative to periodic DFT in these situations

Validation of SCIAMACHY top-of-atmosphere reflectance for aerosol remote sensing using MERIS L1 data

Aerosol remote sensing is very much dependent on the accurate knowledge of the top-of-atmosphere (TOA) reflectance measured by a particular instrument. The status of the calibration of such an instrument is reflected in the quality of the aerosol retrieval. Current data of the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument (operated with the data processor version 5 and earlier) give too small values of the TOA reflectance, compared e.g. to data from MERIS (Medium Resolution Imaging Spectrometer), both operating on ENVISAT (ENVIronmental SATellite). This effect causes retrievals of wrong aerosol optical thickness and disables the processing of aerosol parameters. <br><br> From an inter-comparison of MERIS and SCIAMACHY TOA reflectance, for collocated scenes correction factors are derived to improve the insufficient SCIAMACHY L1 data calibration for data obtained with the processor 5 for the purpose of aerosol remote sensing. The corrected reflectance has been used for tests of remote sensing of the aerosol optical thickness by the BAER (Bremen AErosol Retrieval) approach using SCIAMACHY data

Pedestrian, Crowd, and Evacuation Dynamics

This contribution describes efforts to model the behavior of individual pedestrians and their interactions in crowds, which generate certain kinds of self-organized patterns of motion. Moreover, this article focusses on the dynamics of crowds in panic or evacuation situations, methods to optimize building designs for egress, and factors potentially causing the breakdown of orderly motion.Comment: This is a review paper. For related work see http://www.soms.ethz.c

Gene editing could open up animal organ transplants into humans

The clinical potential and ethical difficulty posed by gene-editing technology, which can “find and replace” targeted genes, is seemingly endless. But while public attention is focused on whether we should use it to change the genes of embryos, application of the technology to genetically modify pig tissues and organs for transplantation into humans could potentially have a bigger and more immediate impact on human health. The transplantation of living cells, tissues, or organs from one species to another is known as xenotransplantation. It has long been championed as a solution to the shortage of human donor organs. Xenotransplantation could be used either as definitive therapy or to “buy time” while the patient waits for a human donor organ. While progress has been slow, trials have demonstrated benefit in patients with type 1 diabetes who are transplanted with porcine pancreatic cells. And gene-editing research published in October shows incredible promise for making xenotransplantation a reality. Xenotransplantation faces two major challenges: the risk of immune rejection and the risk of transmitting diseases from animals to humans (xenozoonosis)

Gene editing advance re‐ignites debate on the merits and risks of animal to human transplantation

In Australia and internationally, the shortage of organ and tissue donors significantly limits the number of patients with critical organ or tissue failure who are able to receive a transplant each year. The rationale for xenotransplantation – the transplantation of living cells, tissues or organs from one species to another – is to meet this shortfall in human donor material. While early clinical trials showed promise, particularly in patients with Type I diabetes whose insulin dependence could be temporarily reversed by the transplantation of porcine islet cells, these benefits have been balanced with scientific, clinical and ethical concerns revolving around the risks of immune rejection and the potential transmission of porcine endogenous retroviruses (PERV) or other infectious agents from porcine grafts to human recipients. However, the advent of CRISPR/Cas9, a revolutionary gene editing technology, has re-ignited interest in the field with the possibility of genetically engineering porcine organs and tissues that are less immunogenic and have virtually no risk of PERV transmission. At the same time, CRISPR/Cas9 may also open up myriad possibilities for tissue engineering and stem cell research which may complement xenotransplantation research by providing an additional source of donor cells, tissues and organs for transplantation into patients. The recent international symposium on gene editing, organised by the US National Academy of Sciences, highlights both the enormous therapeutic potential of CRISPR/Cas9 and the raft of ethical and regulatory challenges that may follow its utilisation in transplantation and in medicine more generally