Charge storage characteristics of ultra-small Pt nanoparticle embedded GaAs based non-volatile memory

Charge storage characteristics of ultra-small Pt nanoparticle embedded devices were characterized by capacitance-voltage measurements. A unique tilt target sputtering configuration was employed to produce highly homogenous nanoparticle arrays. Pt nanoparticle devices with sizes ranging from ∼0.7 to 1.34 nm and particle densities of ∼3.3–5.9 × 1012 cm−2 were embedded between atomic layer deposited and e-beam evaporated tunneling and blocking Al2O3 layers. These GaAs-based non-volatile memory devices demonstrate maximum memory windows equivalent to 6.5 V. Retention characteristics show that over 80% charged electrons were retained after 105 s, which is promising for device applications

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Manganese-Iron Phosphate Nodules at the Groken Site, Gale Crater, Mars

The MSL Curiosity rover investigated dark, Mn-P-enriched nodules in shallow lacustrine/fluvial sediments at the Groken site in Glen Torridon, Gale Crater, Mars. Applying all relevant information from the rover, the nodules are interpreted as pseudomorphs after original crystals of vivianite, (Fe2+,Mn2+)3(PO4)2·8H2O, that cemented the sediment soon after deposition. The nodules appear to have flat faces and linear boundaries and stand above the surrounding siltstone. ChemCam LIBS (laser-induced breakdown spectrometry) shows that the nodules have MnO abundances approximately twenty times those of the surrounding siltstone matrix, contain little CaO, and have SiO2 and Al2O3 abundances similar to those of the siltstone. A deconvolution of APXS analyses of nodule-bearing targets, interpreted here as representing the nodules’ non-silicate components, shows high concentrations of MnO, P2O5, and FeO and a molar ratio P/Mn = 2. Visible to near-infrared reflectance of the nodules (by ChemCam passive and Mastcam multispectral) is dark and relatively flat, consistent with a mixture of host siltstone, hematite, and a dark spectrally bland material (like pyrolusite, MnO2). A drill sample at the site is shown to contain minimal nodule material, implying that analyses by the CheMin and SAM instruments do not constrain the nodules’ mineralogy or composition. The fact that the nodules contain P and Mn in a small molar integer ratio, P/Mn = 2, suggests that the nodules contained a stoichiometric Mn-phosphate mineral, in which Fe did (i.e., could) not substitute for Mn. The most likely such minerals are laueite and strunzite, (Fe2+,Mn2+)3(PO4)2·8H2O and –6H2O, respectively, which occur on Earth as alteration products of other Mn-bearing phosphates including vivianite. Vivianite is a common primary and diagenetic precipitate from low-oxygen, P-enriched waters. Calculated phase equilibria show Mn-bearing vivianite could be replaced by laueite or strunzite and then by hematite plus pyrolusite as the system became more oxidizing and acidic. These data suggest that the nodules originated as vivianite, forming as euhedral crystals in the sediment, enclosing sediment grains as they grew. After formation, the nodules were oxidized—first to laueite/strunzite yielding the diagnostic P/Mn ratio, and then to hematite plus an undefined Mn oxy-hydroxide (like pyrolusite). The limited occurrence of these Mn-Fe-P nodules, both in space and time (i.e., stratigraphic position), suggests a local control on their origin. By terrestrial analogies, it is possible that the nodules precipitated near a spring or seep of Mn-rich water, generated during alteration of olivine in the underlying sediments

Digital Game-Based Learning of the Cell Cycle and its Effects on Students\u27 Academic Achievement and Motivation

The study aims to explore the effects of digital game-based learning on student’s academic achievement and motivation. Previous studies show that the effect of implementing game-based learning within the class positively affects the students’ academic achievement and motivation. The study focuses on the students’ recent Biology course, specifically regarding the cell cycle (mitosis, interphase, cytokinesis). With that said, the game to be used is called Mitosis Mover. Mitosis Mover is an HTML game that teaches students about the basics of the cell cycle. The game is accessible through a website and is structured like a slideshow presentation with occasional multiple-choice questions and interactive elements. The study followed a quantitative approach. The data collection process involves the use of pretests and post-tests for both academic achievement and motivation. The motivation assessment is based on the ARCS model (attention, relevance, confidence, satisfaction). The game implementation occurs after the pretest and before the posttest. To gain a more inferential conclusion from the gathered results, a right-tailed paired sample t-test analysis was performed for both the overall academic achievement and motivation scores. Through this inferential analysis, the implementation of a game-based learning program — in this case, Mitosis Mover! — positively affects the students’ overall academic achievement and motivation

On Trade Wind Cumulus Cold Pools

Abstract Shallow precipitating cumuli within the easterly trades were investigated using shipboard measurements, scanning radar data, and visible satellite imagery from 2 weeks in January 2005 of the Rain in Cumulus over the Ocean (RICO) experiment. Shipboard rainfall rates of up to 2 mm h−1 were recorded almost daily, if only for 10–30 min typically, almost always from clouds within mesoscale arcs. The precipitating cumuli, capable of reaching above 4 km, cooled surface air by 1–2 K, in all cases lowered surface specific humidities by up to 1.5 g kg−1, reduced surface equivalent potential temperatures by up to 6 K, and were often associated with short-lived increases in wind speed. Upper-level downdrafts were inferred to explain double-lobed moisture and temperature sounding profiles, as well as multiple inversions in wind profiler data. In two cases investigated further, the precipitating convection propagated faster westward than the mean surface wind by about 2–3 m s−1, consistent with a density current of depth ~200 m. In their cold pool recovery zones, the surface air temperatures equilibrated with time to the sea surface temperatures, but the surface air specific humidities stayed relatively constant after initial quick recoveries. This suggested that entrainment of drier air from above fully compensated the moistening from surface latent heat fluxes. Recovery zone surface wind speeds and latent heat fluxes were not higher than environmental values. Nonprecipitating clouds developed after the surface buoyancy had recovered (barring encroachment of other convection). The mesoscale arcs favored atmospheres with higher water vapor paths. These observations differed from those of stratocumulus and deep tropical cumulus cold pools

Defective heart development in hypomorphic Lsd1 mice

Lysine-specific demethylase 1 (Lsd1/Aof2/Kdm1a), the first enzyme with specific lysine demethylase activity to be described, demethylates several target proteins, including histones, DNMT1 and p53. Lsd1 can act as either a transcriptional activator or repressor, depending on the histone lysine it demethylates; its specificity for either H3K4 or H3K9 appears to be determined by its binding partners. We have previously demonstrated that a complete loss of this protein results in early embryonic lethality. However, it was also noted that no adult mice homozygous for the floxed allele survived, even though this allele should be indistinguishable from wild-type Lsd1 after splicing removes the LoxP sites. Homozygous pups die perinatally, with most animals showing major heart development defects. The Aof22lox allele contains two point mutations; the resulting protein shows reduced interaction with known binding partners and decreased enzymatic activity. The expression of a very limited subset of genes is altered in the hearts. This includes an increase in CK2beta expression, the regulatory subunit of the CK2 kinase, which results in E-cadherin hyperphosphorylation. These results identify a previously unknown role for Lsd1 in heart development, through the control of E-cadherin phosphorylation

Protein expression in the developmentally-defective hearts.

<p>The expression of proteins in 3 hypomorphic and 2 wild-type control E18.5 hearts was examined by immunoblotting. A decrease in Lsd1 and a major increase in phosphorylation of E-cadherin were noted in the <i>Aof2</i>^2lox/2lox hearts, whereas all other proteins examined showed no obvious changes. In the E-cadherin blot, the arrow indicates the correct E-cadherin band, and the identity of the higher band is unknown. The Ncam antibody recognizes the 140 kDa isoform of this protein. Relevant molecular weight markers are indicated, in kDa, to the right of each panel.</p