Li non-stoichiometry and crystal growth of untwinned 1D quantum spin system Lix Cu2 O2

Floating-zone growth of untwinned single crystal of Li_xCu_2O_2 with high Li content of x ~ 0.99 is reported. Li content of Li_xCu_2O_2 has been determined accurately through combined iodometric titration and thermogravimetric methods, which also ruled out the speculation of chemical disorder between Li and Cu ions. The morphology and physical properties of single crystals obtained from slowing-cooling (SL) and floating-zone (FZ) methods are compared. The floating-zone growth under Ar/O_2=7:1 gas mixture at 0.64 MPa produces large area of untwinned crystal with highest Li content, which has the lowest helimagnetic ordering temperature ~19K in the Li_xCu_2O_2 system.Comment: 4 pages, 3 figure

Design of a Second Generation Electrostatic Precipitator for Martian Atmospheric Dust Mitigation of ISRU Intakes

A second generation electrostatic precipitator for use in the Martian environment has been developed by the Electrostatics and Surface Physics Laboratory (ESPL) at NASA Kennedy Space Center (KSC). This new system was designed to be modular and has three interchangeable test sections, each with a variety of replaceable high voltage electrodes, enabling optimization of the dust collection efficiency of the precipitator. It has the ability to maintain an increased atmospheric flow rate and provide more accurate dust delivery into the test section than was available in the previous prototypes. A majority of the controls for the system are provided by a software package developed to maintain a constant flow rate, low pressure, and electrode current to enable long duration performance characterization. This allows for testing of the technology in a relevant environment similar to those expected to be found in an atmospheric In-Situ Resource Utilization (ISRU) plant on Mars

Internet Predictions

More than a dozen leading experts give their opinions on where the Internet is headed and where it will be in the next decade in terms of technology, policy, and applications. They cover topics ranging from the Internet of Things to climate change to the digital storage of the future. A summary of the articles is available in the Web extras section

Electrical Characteristics of the Mars Electrostatic Precipitator

NASA's next generation Mars missions will include chemical processing plants to convert the Martian atmosphere into consumable products needed to support astronaut activities. The thin, mostly carbon dioxide atmosphere of Mars is estimated to have 5-10 particles/cu. cm which have a radius of 1.6-2.27 microns on average. These dust particles could potentially foul the chemical process or reduce the purity of the products. Electrostatic precipitation is one possible solution to remove dust particles from the ingested Mars atmosphere. The Electrostatics and Surface Physics Laboratory at NASA's Kennedy Space Center has developed an electrostatic precipitator testbed to understand the intricacies of corona discharges in dusty flows simulating Mars atmospheric conditions. Current-voltage trends have been established for a number of precipitator flow conditions. Corona onset voltage and streamer onset voltage trends versus pressure are also established

Equation of State for Natural Almandine, Spessartine, Pyrope Garnet: Implications for Quartz-In-Garnet Elastic Geobarometry

The equation of state (EoS) of a natural almandine74spessartine13pyrope10grossular3 garnet of a typical composition found in metamorphic rocks in Earth’s crust was obtained using single crystal synchrotron X-ray diffraction under isothermal room temperature compression. A third-order Birch-Murnaghan EoS was fitted to P-V data and the results are compared with published EoS for iron, manganese, magnesium, and calcium garnet compositional end-members. This comparison reveals that ideal solid solution mixing can reproduce the EoS for this intermediate composition of garnet. Additionally, this new EoS was used to calculate geobarometry on a garnet sample from the same rock, which was collected from the Albion Mountains of southern Idaho. Quartz-ingarnet elastic geobarometry was used to calculate pressures of quartz inclusion entrapment using alternative methods of garnet mixing and both the hydrostatic and Grunëisen tensor approaches. QuiG barometry pressures overlap within uncertainty when calculated using EoS for pure endmember almandine, the weighted averages of end-member EoS, and the EoS presented in this study. Grunëisen tensors produce apparent higher pressures relative to the hydrostatic method, but with large uncertainties

Updated Three-Stage Model for the Peopling of the Americas

Background: We re-assess support for our three stage model for the peopling of the Americas in light of a recent report that identified nine non-Native American mitochondrial genome sequences that should not have been included in our initial analysis. Removal of these sequences results in the elimination of an early (i.e.,40,000 years ago) expansion signal we had proposed for the proto-Amerind population. Methodology/Findings: Bayesian skyline plot analysis of a new dataset of Native American mitochondrial coding genomes confirms the absence of an early expansion signal for the proto-Amerind population and allows us to reduce the variation around our estimate of the New World founder population size. In addition, genetic variants that define New World founder haplogroups are used to estimate the amount of time required between divergence of proto-Amerinds from the Asian gene pool and expansion into the New World. Conclusions/Significance: The period of population isolation required for the generation of New World mitochondrial founder haplogroup-defining genetic variants makes the existence of three stages of colonization a logical conclusion. Thus, our three stage model remains an important and useful working hypothesis for researchers interested in the peopling of th

Whole number thinking, learning and development: neuro-cognitive, cognitive and developmental approaches

The participants of working group 2 presented a broad range of studies, 11 papers in total, related to whole number learning representing research groups from 11 countries as follows. Two large cross-sectional studies focused on developmental aspects of young children’s number learning provide a lens for re-examining ‘traditional’ features of number acquisition. van den Heuvel-Panhuizen (the Netherlands) presented a co-authored paper with Elia (Cyprus; Elia and van den Heuvel-Panhuizen 2015) on a cross-cultural study of kindergartners’ number competence focused on counting, additive and multiplicative thinking. Second, Milinković (2015) examined the development of young Serbian children’s initial understanding of representations of whole numbers and counting strategies in a large study of 3- to 7-year-olds. Children’s invented (formal) representations such as set representation and the number line were found to be limited in their recordings. In a South African study focused on early counting and addition, Roberts (2015) directs attention to the role of teachers by providing a framework to support teachers’ interpretation of young disadvantaged learners’ representations of number when engaging with whole number additive tasks. Some papers reflected the increasing role of neuroscientific concepts and methodologies utilised in research on WNA learning and development. Sinclair and Coles (2015) drew upon neuroscientific research to highlight the significant role of symbol-to-symbol connections and the use of fingers and touch counting exempli- fied by the TouchCounts iPad app. Gould (2015) reported aspects of a large Australian large study of children in the first years of schooling aimed at improving numeracy and literacy in disadvantaged communities. A case study exemplified how numerals were identified by relying on a mental number line by using location to retrieve number names. This raised the question addressed in the neuroscientific work of Dehaene and other papers focused on individual differences in how the brain processes numbers. The Italian PerContare1 project (Baccaglini-Frank 2015) built upon the collaboration between cognitive psychologists and mathematics educators, aimed at developing teaching strategies for preventing and addressing early low achievement in arithmetic. It takes an innovative approach to the development of number sense that is grounded upon a kinaesthetic and visual-spatial approach to part-whole relationships. Mulligan and Woolcott (2015) provided a discussion paper on the underlying nature of number. They presented a broader view of mathematics learning (including WNA) as linked to spatial interaction with the environment; the concept of connectivity across concepts and the development of underlying pattern and structural relationships are central to their approach

Human and Chimpanzee Gene Expression Differences Replicated in Mice Fed Different Diets

Although the human diet is markedly different from the diets of closely related primate species, the influence of diet on phenotypic and genetic differences between humans and other primates is unknown. In this study, we analyzed gene expression in laboratory mice fed diets typical of humans and of chimpanzees. The effects of human diets were found to be significantly different from that of a chimpanzee diet in the mouse liver, but not in the brain. Importantly, 10% of the genes that differ in their expression between humans and chimpanzee livers differed also between the livers of mice fed the human and chimpanzee diets. Furthermore, both the promoter sequences and the amino acid sequences of these diet-related genes carry more differences between humans and chimpanzees than random genes. Our results suggest that the mouse can be used to study at least some aspects of human-specific traits

Editing site analysis in a gymnosperm mitochondrial genome reveals similarities with angiosperm mitochondrial genomes

Sequence analysis of organelle genomes and comprehensive analysis of C-to-U editing sites from flowering and non-flowering plants have provided extensive sequence information from diverse taxa. This study includes the first comprehensive analysis of RNA editing sites from a gymnosperm mitochondrial genome, and utilizes informatics analyses to determine conserved features in the RNA sequence context around editing sites. We have identified 565 editing sites in 21 full-length and 4 partial cDNAs of the 39 protein-coding genes identified from the mitochondrial genome of Cycas taitungensis. The information profiles and RNA sequence context of C-to-U editing sites in the Cycas genome exhibit similarity in the immediate flanking nucleotides. Relative entropy analyses indicate that similar regions in the 5′ flanking 20 nucleotides have information content compared to angiosperm mitochondrial genomes. These results suggest that evolutionary constraints exist on the nucleotide sequences immediately adjacent to C-to-U editing sites, and similar regions are utilized in editing site recognition