Breakdown of the Korringa Law of Nuclear Spin Relaxation in Metallic GaAs

We present nuclear spin relaxation measurements in GaAs epilayers using a new pump-probe technique in all-electrical, lateral spin-valve devices. The measured T1 times agree very well with NMR data available for T > 1 K. However, the nuclear spin relaxation rate clearly deviates from the well-established Korringa law expected in metallic samples and follows a sub-linear temperature dependence 1/T1 ~ T^0.6 for 0.1 K < T < 10 K. Further, we investigate nuclear spin inhomogeneities.Comment: 5 pages, 4 (color) figures. arXiv admin note: text overlap with arXiv:1109.633

Ethnomusicology Matters:Influencing Social and Political Realities

This book gathers international voices from the field of ethnomusicology discussing the socio-political relevance of the discipline. The articles draw from contemporary discourses that take into account the role of music and dance in shaping social and political realities. An important field connected to political relevance is heritage, either in connection with the UNESCO or with archives. Ontologies of indigenous groups and their relevance in knowledge production is discussed in ethnomusicology nowadays as well as the possibilities of decolonising the discipline. Two articles from ethno-choreology explore dance from the gender perspective and in the post-socialist political structures. Different approaches from applied ethnomusicology deal with social justice, participatory dialogical practice, and the socio-political relevance of performance. Forced migration is seen as comprehensive topic for future ethnomusicology. The contents of the book mirror influential discourses of ethnomusicology today that will definitely shape the future development of the discipline

Exobiology of the Venusian Clouds: New Insights into Habitability through Terrestrial Models and Methods of Detection

The search for life beyond Earth has focused on Mars and the icy moons Europa and Enceladus, all of which are considered a safe haven for life due to evidence of current or past water. The surface of Venus, on the other hand, has extreme conditions that make it a nonhabitable environment to life as we know it. This is in contrast, however, to its cloud layer, which, while still an extreme environment, may prove to be a safe haven for some extreme forms of life similar to extremophiles on Earth. We consider the venusian clouds a habitable environment based on the presence of (1) a solvent for biochemical reactions, (2) appropriate physicochemical conditions, (3) available energy, and (4) biologically relevant elements. The diversity of extreme microbial ecosystems on Earth has allowed us to identify terrestrial chemolithoautotrophic microorganisms that may be analogs to putative venusian organisms. Here, we hypothesize and describe biological processes that may be performed by such organisms in the venusian clouds. To detect putative venusian organisms, we describe potential biosignature detection methods, which include metal-microbial interactions and optical methods. Finally, we describe currently available technology that can potentially be used for modeling and simulation experiments. © Copyright 2021, Mary Ann Liebert, Inc., publishers 2021.NASA HQ Planetary ScienceSpace Research Institute of the Russian Academy of SciencesUniversity of Wisconsin-Madison, UWAustrian Science Fund, FWF, (V333)The work presented here was motivated by fruitful dialogue at the 2019 Venus Cloud Layer Habitability and Landing Site Selection workshop organized by the Roscosmos-IKI/NASA Venera-D Joint Science Definition Team and supported by NASA HQ Planetary Science (A. Ocampo, Lead Venus Scientist) and Astrobiology programs (M. Voytek, Senior Scientist for Astrobiology) and the Space Research Institute of the Russian Academy of Sciences (IKI RAN). JAC acknowledges the support of the Genome Sciences Training Program at University of Wisconsin–Madison. TM is grateful to the Austrian Science Fund (FWF) for providing support through the Elise-Richter Research fellowship (V333). We thank Sanjay Limaye for his support, including of this publication, and for resparking the conversation on Venus astrobiology

Development of Diamond Tracking Detectors for High Luminosity Experiments at LHC

During 2006 detectors based on new polycrystalline CVD (pCVD) material were produced as candidates for use in LHC experiments. The first full size diamond pixel module with ATLAS specifications using a $2 \times 6$ cm$^2$ pCVD sample was characterized in the 2006 CERN test beam. Radiation damage studies performed outside of CERN corroborate the radiation hardness of this material. Radiation hardness studies at CERN using the highest quality diamond were deferred until 2007 due to the PS magnet problem. ATLAS, CMS, ALICE and LHCb are planning to use diamond for their beam conditions monitoring systems. Construction of the BCM system for ATLAS was completed in 2006 and the BCM modules were characterized in 2006 CERN test beams. Similar devices are under construction for the CMS, ALICE and LHCb experiments. Single-crystal CVD (scCVD) samples were produced and made available to RD42 institutes. The first scCVD diamond pixel device was constructed and tested in the 2006 CERN test beams. In this report we present the progress and work done by the RD42 collaboration on the development of CVD diamond material for radiation detectors

A Bit-Vector Differential Model for the Modular Addition by a Constant

ARX algorithms are a class of symmetric-key algorithms constructed by Addition, Rotation, and XOR, which achieve the best software performances in low-end microcontrollers. To evaluate the resistance of an ARX cipher against differential cryptanalysis and its variants, the recent automated methods employ constraint satisfaction solvers, such as SMT solvers, to search for optimal characteristics. The main difficulty to formulate this search as a constraint satisfaction problem is obtaining the differential models of the non-linear operations, that is, the constraints describing the differential probability of each non-linear operation of the cipher. While an efficient bit-vector differential model was obtained for the modular addition with two variable inputs, no differential model for the modular addition by a constant has been proposed so far, preventing ARX ciphers including this operation from being evaluated with automated methods. In this paper, we present the first bit-vector differential model for the n-bit modular addition by a constant input. Our model contains O(log2(n)) basic bit-vector constraints and describes the binary logarithm of the differential probability. We also represent an SMT-based automated method to look for differential characteristics of ARX, including constant additions, and we provide an open-source tool ArxPy to find ARX differential characteristics in a fully automated way. To provide some examples, we have searched for related-key differential characteristics of TEA, XTEA, HIGHT, and LEA, obtaining better results than previous works. Our differential model and our automated tool allow cipher designers to select the best constant inputs for modular additions and cryptanalysts to evaluate the resistance of ARX ciphers against differential attacks.acceptedVersio

Human Movement Is Both Diffusive and Directed

Understanding the influence of the built environment on human movement requires quantifying spatial structure in a general sense. Because of the difficulty of this task, studies of movement dynamics often ignore spatial heterogeneity and treat movement through journey lengths or distances alone. This study analyses public bicycle data from central London to reveal that, although journey distances, directions, and frequencies of occurrence are spatially variable, their relative spatial patterns remain largely constant, suggesting the influence of a fixed spatial template. A method is presented to describe this underlying space in terms of the relative orientation of movements toward, away from, and around locations of geographical or cultural significance. This produces two fields: one of convergence and one of divergence, which are able to accurately reconstruct the observed spatial variations in movement. These two fields also reveal categorical distinctions between shorter journeys merely serving diffusion away from significant locations, and longer journeys intentionally serving transport between spatially distinct centres of collective importance. Collective patterns of human movement are thus revealed to arise from a combination of both diffusive and directed movement, with aggregate statistics such as mean travel distances primarily determined by relative numbers of these two kinds of journeys