Survival of the NASA Mars Odyssey isolate Acinetobacter radioresistens 50v1 on different spaceflight relevant antimicrobial surfaces

Since many years, human mankind travels to space. One of our mayor interests is the health of astronauts and the protection of the spacecraft. Apart from external influences, the microbial burden inside of the International Space Station (ISS) may be dangerous and must be limited to a minimum. To ensure the status and the protection of the crew as well as the spacecraft itself, it is necessary to determine the survival of microorganisms on different surfaces. Microorganisms are constantly changing their strategy of survival, primarily induced by extreme environmental conditions, such as space conditions, compared to their terrestrial habitats. However, the increased levels in resistance and robustness possibly play a sensitive role in evolving new virulence factors in the space environment. One of the bacteria on the NASA Mars Odyssey spacecraft, which have been isolated, is the Gram-negative, non-motile bacterium Acinetobacter radioresistens. Apart from Deinococcus radiodurans, A. radioresistens shows similar levels in radiation and oxidative stress tolerance (McCoy et al., 2012). In our work, we used the strain 50v1, isolated from the surface of the Mars Odyssey spacecraft as well as the type strain DSM6976, which was isolated on Earth from cotton and soil samples. We investigated the resistance regarding in their desiccation tolerance on metallic surfaces including materials with different antimicrobial properties. For those experiments we exposed and desiccated both strains on the different surfaces (such as copperand silver-containing materials) and determined the survival over different time points. First results show a high resistance of the spacecraft isolated strain compared to the type strain. These results give implications about the higher survivability of environmental microorganisms and highlight the essence of bioburden reduction and improve sterilization approaches/techniques for upcoming space exploration missions towards the search for life outside Earth

Formulation of the Spinor Field in the Presence of a Minimal Length Based on the Quesne-Tkachuk Algebra

In 2006 Quesne and Tkachuk (J. Phys. A: Math. Gen. {\bf 39}, 10909, 2006) introduced a (D+1)-dimensional $(\beta,\beta')$-two-parameter Lorentz-covariant deformed algebra which leads to a nonzero minimal length. In this work, the Lagrangian formulation of the spinor field in a (3+1)-dimensional space-time described by Quesne-Tkachuk Lorentz-covariant deformed algebra is studied in the case where $\beta'=2\beta$ up to first order over deformation parameter $\beta$. It is shown that the modified Dirac equation which contains higher order derivative of the wave function describes two massive particles with different masses. We show that physically acceptable mass states can only exist for $\beta<\frac{1}{8m^{2}c^{2}}$. Applying the condition $\beta<\frac{1}{8m^{2}c^{2}}$ to an electron, the upper bound for the isotropic minimal length becomes about $3 \times 10^{-13}m$. This value is near to the reduced Compton wavelength of the electron $(\lambda_c = \frac{\hbar}{m_{e}c} = 3.86\times 10^{-13} m)$ and is not incompatible with the results obtained for the minimal length in previous investigations.Comment: 11 pages, no figur

Deep Eyes: Binocular Depth-from-Focus on Focal Stack Pairs

Human visual system relies on both binocular stereo cues and monocular focusness cues to gain effective 3D perception. In computer vision, the two problems are traditionally solved in separate tracks. In this paper, we present a unified learning-based technique that simultaneously uses both types of cues for depth inference. Specifically, we use a pair of focal stacks as input to emulate human perception. We first construct a comprehensive focal stack training dataset synthesized by depth-guided light field rendering. We then construct three individual networks: a Focus-Net to extract depth from a single focal stack, a EDoF-Net to obtain the extended depth of field (EDoF) image from the focal stack, and a Stereo-Net to conduct stereo matching. We show how to integrate them into a unified BDfF-Net to obtain high-quality depth maps. Comprehensive experiments show that our approach outperforms the state-of-the-art in both accuracy and speed and effectively emulates human vision systems

Quantum Monte Carlo calculation of the finite temperature Mott-Hubbard transition

We present clear numerical evidence for the coexistence of metallic and insulating dynamical mean field theory(DMFT) solutions in a half-filled single-band Hubbard model with bare semicircular density of states at finite temperatures. Quantum Monte Carlo(QMC) method is used to solve the DMFT equations. We discuss important technical aspects of the DMFT-QMC which need to be taken into account in order to obtain the reliable results near the coexistence region. Among them are the critical slowing down of the iterative solutions near phase boundaries, the convergence criteria for the DMFT iterations, the interpolation of the discretized Green's function and the reduction of QMC statistical and systematic errors. Comparison of our results with those of other numerical methods is presented in a phase diagram.Comment: 4 pages, 5 figure

Deep Depth From Focus

Depth from focus (DFF) is one of the classical ill-posed inverse problems in computer vision. Most approaches recover the depth at each pixel based on the focal setting which exhibits maximal sharpness. Yet, it is not obvious how to reliably estimate the sharpness level, particularly in low-textured areas. In this paper, we propose `Deep Depth From Focus (DDFF)' as the first end-to-end learning approach to this problem. One of the main challenges we face is the hunger for data of deep neural networks. In order to obtain a significant amount of focal stacks with corresponding groundtruth depth, we propose to leverage a light-field camera with a co-calibrated RGB-D sensor. This allows us to digitally create focal stacks of varying sizes. Compared to existing benchmarks our dataset is 25 times larger, enabling the use of machine learning for this inverse problem. We compare our results with state-of-the-art DFF methods and we also analyze the effect of several key deep architectural components. These experiments show that our proposed method `DDFFNet' achieves state-of-the-art performance in all scenes, reducing depth error by more than 75% compared to the classical DFF methods.Comment: accepted to Asian Conference on Computer Vision (ACCV) 201

The influence of shock pressure, pre-shock temperature, and host rock composition on the survival rate of endolithic microorganisms during impact ejection from Mars

Petrographic and biological analysis of shock recovery experiments confirms the possible life transport due to an impact from Mars to Earth

"Killing them softly" … challenges in the Bacillus subtilis spore inactivation by plasma sterilization

The elimination of bacterial endospores is absolutely essential in numerous fields, ranging from hospital hygiene, the food processing industry, all the way to the space industry. A major goal of space exploration is the search for signatures of life forms and biomolecules on other planetary bodies and moons in our solar system. The transfer of microorganisms or biomolecules of terrestrial origin to critical areas of exploration is of particular risk to impact the development and integrity of life-detection missions.1 Plasma sterilization is a promising alternative to conventional sterilization methods for spaceflight purposes. Due to their extraordinary resistance properties, spores of the Gram-positive bacterium Bacillus subtilis are used as biological indicators for decontamination studies to identify the relevant mechanism that leads to the rapid bacterial inactivation.1,3 Here, we present novel insights into the key factors involved in spore inactivation by low pressure plasma sterilization using a double inductively-coupled plasma reactor. (2,4) In order to standardize the assessment of inactivation efficiencies by plasma discharges, an electrically driven spray deposition device was developed, allowing fast, reproducible, and homogeneous preparation of B. subtilis spore monolayers. We demonstrate that plasma discharges caused significant physical damage to spore surface structures as visualized by atomic force microscopy. A systematic analysis of B. subtilis spores lacking individual coat and crust layers - the first barrier to environmental influences – revealed the coat to be one of the contributing factors in the spore resistance to plasma sterilization. (2-4) Furthermore, we identified spore-specific and general protection mechanisms and DNA repair pathways during spore germination and outgrowth after plasma treatment, leading to a better understanding of the complex molecular mechanisms involved in the inactivation by plasma sterilization processes

Determining the global minimum of Higgs potentials via Groebner bases - applied to the NMSSM

Determining the global minimum of Higgs potentials with several Higgs fields like the next-to-minimal supersymmetric extension of the Standard Model (NMSSM) is a non-trivial task already at the tree level. The global minimum of a Higgs potential can be found from the set of all its stationary points defined by a multivariate polynomial system of equations. We introduce here the algebraic Groebner basis approach to solve this system of equations. We apply the method to the NMSSM with CP conserving as well as CP violating parameters. The results reveal an interesting stationary-point structure of the potential. Requiring the global minimum to give the electroweak symmetry breaking observed in Nature excludes large parts of the parameter space.Comment: 10 pages, 2 figure

Stereo-EEG exploration in the insula/operculum in paediatric patients with refractory epilepsy

PURPOSE: Failure to recognise involvement of the insula / opercula (I/O) region is associated with poor outcome in epilepsy surgery. Recognition is challenging due to high connectivity with adjacent structures resulting in variable and misleading semiology, often subjective and therefore likely to be underreported by children. In this study we explored prevalence and characteristics of I/O involvement in paediatric patients undergoing sEEG exploration. METHOD: We retrospectively included all consecutive patients undergoing sEEG at our centre between 11/2014 and 01/2018 with at least three contacts within I/O and excluded those with undetermined seizure onset zone (SOZ) by sEEG. We divided patients into three groups: 1) SOZ in I/O, 2) spread to I/O and 3) no I/O involvement. We compared pre-invasive characteristics, sEEG results, surgery and outcome for each group. RESULTS: 29 of all 53 consecutive patients had an identified SOZ by sEEG and at least three contacts within the I/O and were included. 41% had I/O SOZ, 38% had I/O spread and 21% had no I/O involvement. Insula associated symptoms described in adult literature were not statistically different between the three groups. Complications due to sEEG were low (2 of 53 patients). Following I/O surgery, 63% were seizure free while an additional 26% of patients achieved seizure reduction. Postoperative deficits were seen in 75% of the patients but completely resolved in all but one patient. CONCLUSIONS: Our data suggest an important role of the I/O region with frequent onset or propagation to the I/O region (at least 64% of all 53 sEEG cases). Semiology appears less specific than in adults. Insula depth electrode insertion is safe with subsequent good surgical outcomes albeit common transient deficits