SAperI: Approaching Gender Gap Using Spatial Ability Training Week in High-School Context

The purpose of this paper is to describe the structure of a girls summer school, “SAperI – Spatial Ability per l’Ingegneria” (in English, “Knowledge – Spatial Ability for Engineering”), and to illustrate its impact on spatial ability development and future career preferences on those who participated in the week long summer school compared to a control group that did not participate.The 5 days school,organized by Politecnico di Torino (Italy), was included in a larger project addressing 17 years old high-school students. Thirtyseven girls actively took part in a summer school, while 167 students (both males and females) were tested as a controlled group.For those who attended the summer school, significant gains were observed in four measures of spatial ability - mental rotation, spatialvisualization, mental cutting and paper folding. For a minority of participants, scores on one of these tests, paper folding, were lower when measured at the end of the summer school but this was an exception. Furthermore, when tested several months after the summer school, the gains in spatial ability that were made during the course were maintained indicating stability over time with regard to the improvement in spatial ability.In terms of the experience of taking the course, the feedback provided was very positive and all but one participant would recommend the summer school to othergirls at this stage of high school

Chondrule-Forming Shock Fronts in the Solar Nebula: A Possible Unified Scenario for Planet and Chondrite Formation

Chondrules are mm-sized spherules found throughout primitive, chondritic meteorites. Flash heating by a shock front is the leading explanation of their formation. However, identifying a mechanism for creating shock fronts inside the solar nebula has been difficult. In a gaseous disk capable of forming Jupiter, the disk must have been marginally gravitationally unstable at and beyond Jupiter's orbit. We show that this instability can drive inward spiral shock fronts with shock speeds of up to about 10 km/s at asteroidal orbits, sufficient to account for chondrule formation. Mixing and transport of solids in such a disk, combined with the planet-forming tendencies of gravitational instabilities, results in a unified scenario linking chondrite production with gas giant planet formation.Comment: 2 figures. ApJ Letters, in pres

Spatial Encoding Strategy Theory: The Relationship between Spatial Skill and STEM Achievement

Learners’ spatial skill is a reliable and significant predictor of achievement in STEM, including computing, education. Spatial skill is also malleable, meaning it can be improved through training. Most cognitive skill training improves performance on only a narrow set of similar tasks, but researchers have found ample evidence that spatial training can broadly improve STEM achievement. We do not yet know the cognitive mechanisms that make spatial skill training broadly transferable when other cognitive training is not, but understanding these mechanisms is important for developing training and instruction that consistently benefits learners, especially those starting with low spatial skill. This paper proposes the spatial encoding strategy (SpES) theory to explain the cognitive mechanisms connecting spatial skill and STEM achievement. To motivate SpES theory, the paper reviews research from STEM education, learning sciences, and psychology. SpES theory provides compelling post hoc explanations for the findings from this literature and aligns with neuroscience models about the functions of brain structures. The paper concludes with a plan for testing the theory’s validity and using it to inform future research and instruction. The paper focuses on implications for computing education, but the transferability of spatial skill to STEM performance makes the proposed theory relevant to many education communities

Highly-accurate 5-axis flank CNC machining with conical tools

A new method for $5$-axis flank computer numerically controlled (CNC) machining using a predefined set of tappered ball-end-mill tools (aka conical) cutters is proposed. The space of lines that admit tangential motion of an associated truncated cone along a general, doubly curved, free-form surface is explored. These lines serve as discrete positions of conical axes in 3D space. Spline surface fitting is used to generate a ruled surface that represents a single continuous sweep of a rigid conical milling tool. An optimization based approach is then applied to globally minimize the error between the design surface and the conical envelope. Our computer simulation are validated with physical experiments on two benchmark industrial datasets, reducing significantly the execution times while preserving or even reducing the milling error when compared to the state-of-the-art industrial software

AA-Amyloidosis Can Be Transferred by Peripheral Blood Monocytes

Spongiform encephalopathies have been reported to be transmitted by blood transfusion even prior to the clinical onset. Experimental AA-amyloidosis shows similarities with prion disease and amyloid-containing organ-extracts can prime a recipient for the disease. In this systemic form of amyloidosis N-terminal fragments of the acute-phase reactant apolipoprotein serum amyloid A are the main amyloid protein. Initial amyloid deposits appear in the perifollicular region of the spleen, followed by deposits in the liver. We used the established murine model and induced AA-amyloidosis in NMRI mice by intravenous injections of purified amyloid fibrils (‘amyloid enhancing factor’) combined with inflammatory challenge (silver nitrate subcutaneously). Blood plasma and peripheral blood monocytes were isolated, sonicated and re-injected into new recipients followed by an inflammatory challenge during a three week period. When the animals were sacrificed presence of amyloid was analyzed in spleen sections after Congo red staining. Our result shows that some of the peripheral blood monocytes, isolated from animals with detectable amyloid, contained amyloid-seed that primed for AA-amyloid. The seeding material seems to have been phagocytosed by the cells since the AA-precursor (SAA1) was found not be expressed by the monocytes. Plasma recovered from mice with AA amyloidosis lacked seeding capacity. Amyloid enhancing activity can reside in monocytes recovered from mice with AA-amyloidosis and in a prion-like way trigger amyloid formation in conjunction with an inflammatory disorder. Human AA-amyloidosis resembles the murine form and every individual is expected to be exposed to conditions that initiate production of the acute-phase reactant. The monocyte-transfer mechanism should be eligible for the human disease and we point out blood transfusion as a putative route for transfer of amyloidosis

Jurassic sedimentation in the Cleveland Basin : a review

This review combines two Presidential Addresses (2005, 2006) and aims to provides an up-to-date overview of the stratigraphy and sedimentation of the Jurassic sequence of the Cleveland Basin (Yorkshire), including poorly known data from the western outcrop. These fascinating rocks have been the focus of geological research since the 18th Century and have had a profound influence on the development of the geological sciences. Throughout the 20th Century, the excellent coastal exposures have acted as a magnet for palaeontologists, stratigraphers, sedimentologists and geochemists, as a natural geological laboratory, and in recent decades, the coastal exposures received increased scientific interest as a result of their analogy with hydrocarbon source and reservoir rocks in the North Sea. Designation of the international Global Stratotype Section and Point (GSSP) for the Sinemurian–Pliensbachian stage boundary in Robin Hood's Bay, the establishment of the Dinosaur Coast, and development of the Rotunda Museum in Scarborough have all given the regional geology additional importance. The Lias Group (Hettangian–Toarcian age; 199.6–175.6 Ma), exposed in the well known coastal sections, is illustrated by the fully cored Felixkirk Borehole, located at the western margin of the outcrop, and is one of the best examples of shallow marine sedimentation in an epeiric shelf-sea setting. It comprises two large-scale, upward coarsening cycles, namely the Redcar Mudstone to Staithes Sandstone cycle, followed by the Cleveland Ironstone to Blea Wyke Sandstone cycle. Within this broad pattern, smaller scale transgressive–regressive cycles are described from stratigraphically expanded and reduced successions. Detailed ammonite biostratigraphy provides a finely calibrated temporal framework to study the variations in sedimentation, which include storm-generated limestones and sandstones (‘tempestites’) interbedded with mudstone deposited during fair-weather periods. Hemipelagic mud, occasionally organic-rich, reflects deeper-water anoxic events that may indicate a response to global climate change. In cores, the tempestite beds (Hettangian–Sinemurian) are characterized by sharp bases that, at outcrop, are often masked by downward penetrating burrows. Cyclicity on a centimetre scale in the overlying Pliensbachian ‘Banded Shales’ may be the result of orbitally induced, climatic cycles. Gradational upward coarsening to the Staithes Sandstone Formation marks a transition to sand-rich tempestite deposits, characterized by low angle and swaley cross-lamination, interbedded with sand-starved units (striped siltstones). The sands were probably deposited from sediment-laden, storm-surge and ebb currents in inner- and mid-shelf settings; the sandy substrate was, at some levels, extensively bioturbated by deposit feeding organisms that produced a spectacular range of trace fossil assemblages characteristic of shoreface, inner-, mid-, and outer-shelf settings. Intrabasinal tectonics was a controlling factor during deposition of both the Staithes Sandstone and the overlying Cleveland Ironstone (Late Pliensbachian). The influx of sand is attributed to hinterland uplift and increased sediment flux. More marked intraformational uplift during deposition of the Cleveland Ironstone is manifested in a much attenuated succession in the west of the basin (Felixkirk); southwards, towards the Market Weighton High, the Pecten/Main Seam of the ironstone oversteps unconformably onto progressively older beds to rest on the lower part of the Redcar Mudstone Formation. Ironstone, in the form of berthierine ooids and sideritic mud, was deposited during 5–6 cycles (in coastal exposures) of high sea-level stands that cut off siliciclastic influx from the low-gradient hinterland; regressive, upward-shoaling intervals are marked by interbedded, bioturbated siltstone and fine-grained sandstone. The Toarcian succession (Whitby Mudstone and Blea Wyke Sandstone formations) continues the second upward coarsening cycle in response to increased subsidence, rising sea-level, and an influx of siliciclastic sand. Oxygenated, open marine mud was deposited during the initial deepening phase, followed by bituminous mud, attributed to ocean-water stratification and the establishment of anoxic bottom conditions; in the west of the basin an upward shoaling sequence suggests that water depths were not as great. Recent research on the geochemistry and stable isotope signatures across this early Toarcian interval indicates a widespread, global anoxic event, possibly attributed to the release of methane hydrate on the ocean floor. The Alum Shale Member represents increasingly oxygenated bottom conditions and an upward coarsening motif with passage to the Blea Wyke Sandstone Formation, which is preserved only in the Peak Trough, an actively subsiding graben. Basin uplift accompanied by gentle folding in late Toarcian to Aalenian times removed much of the late Toarcian succession so that the Middle Jurassic Dogger Formation (Aalenian), a complex, condensed, shallow water unit rests unconformably on beds as low as the Alum Shale over much of the basin. Deep boreholes and revision mapping by the British Geological Survey (BGS) in the west of the outcrop have allowed a fuller, basin-wide synthesis of the palaeoenvironments and the influence of intra-Jurassic tectonics during Mid- to Late Jurassic times. During Mid-Jurassic times the low-lying, paralic coastal plain, typified by braided and meandering fluvial systems and lacustrine deposits was invaded by marine incursions from the south and east. Each transgressive event was different in its geographical penetration across the coastal plain, resulting in varied lithofacies and palaeoenvironments including ooidal ironstone and lime mud (Eller Beck Formation), peloid and ooid carbonate shoals (Lebberston Member), and tidal sand bars, pelloidal limestones and nearshore marine muds (Scarborough Formation). Trace fossils, including dinosaur footprints, and macro-plant fossils tell us much about the palaeoenvironments on the coastal plain, during this time interval (175.6–164.7 Ma) that was characterized by a warm, seasonal climate. The basin wide transgression and marked global sea-level rise represented by the Cornbrash Formation, marks deposition in a shallow marine environment during the Callovian, followed by sand (Osgodby Formation) and deeper water muds (Oxford Clay Formation) that spread northwards from the East Midlands over the Market Weighton High during the Oxfordian. Subsequent shallowing of the basin resulted in the establishment of a carbonate/siliciclastic platform typified by ooidal shoals, coral patch reefs and sponge spicule-rich marine sands (Corallian Group). Their complex sedimentation pattern was influenced by local infra-Oxfordian tectonics related to the Howardian–Flamborough Fault Belt. Although the Ampthill Clay and Kimmeridge Clay formations, the latter representing the most important regional hydrocarbon source rock, are not well-exposed, recent boreholes in the Cleveland Basin have allowed a much better understanding of the hemi-pelagic marine environment (both oxic and anoxic) during this phase of sedimentation which marks a global sea-level rise. Although well-studied by world standards, the Jurassic sediments of the Cleveland Basin continue to throw up surprises and advances in our understanding of the Earth as a dynamic system over a period of c. 30 million years. These studies have directly and indirectly influenced our understanding of the Earth as a system, and have played an important role in educating non-specialists, undergraduates and professional geologists over many decades

Predicting bedforms and primary current stratification in cohesive mixtures of mud and sand

The use of sedimentary structures as indicators of flow and sediment morphodynamics in ancient sediments lies at the very heart of sedimentology, and allows reconstruction of formative flow conditions generated in a wide range of grain sizes and sedimentary environments. However, the vast majority of past research has documented and detailed the range of bedforms generated in essentially cohesionless sediments that lack the presence of mud within the flow and within the sediment bed itself. Yet most sedimentary environments possess fine-grained sediments and recent work has shown how the presence of this fine sediment may substantially modify the fluid dynamics of such flows. It is increasingly evident that understanding the influence of mud, and the presence of cohesive forces, is essential to permit a fuller interpretation of many modern and ancient sedimentary successions. In this paper, the present state of knowledge on the stability of current- and wave-generated bedforms and their primary current stratification is reviewed, and a new extended bedform phase diagram is presented that summarizes the bedforms generated in mixtures of sand and mud under rapidly decelerated flows. This diagram provides a phase space using the variables of yield strength and grain mobility as the abscissa and ordinate axes, respectively, and defines the stability fields of a range of bedforms generated under flows that have modified fluid dynamics owing to the presence of suspended sediment within the flow. Our results also present unique data on a range of bedforms generated in such flows, whose recognition is essential to help interpret such deposits in the ancient sedimentary record, including the following: (1) heterolithic stratification, comprising alternating laminae or layers of sand and mud; (2) the preservation of low-amplitude bed-waves, large current ripples and bed scours with intrascour composite bedforms; (3) low-angle cross-lamination and long lenses and streaks of sand and mud formed by bed-waves; (4) complex stacking of reverse bedforms, mud layers and low-angle cross-lamination on the upstream face of bed scours; (5) planar bedding comprising stacked mud–sand couplets. Furthermore, the results shown herein demonstrate that flow variability is not required to produce deposits consisting of interbedded sand and muds, and that the nature of flaser, wavy and lenticular bedding (sensu Reineck & Wunderlich 1968) may also need reconsideration in the deposits of such sediment-laden flows

Validation of reference genes for expression analysis in the salivary gland and the intestine of Rhodnius prolixus (Hemiptera, Reduviidae) under different experimental conditions by quantitative real-time PCR

<p>Abstract</p> <p>Background</p> <p><it>Rhodnius prolixus </it>is a blood-feeding insect that can transmit <it>Trypanosoma cruzi </it>and <it>Trypanosoma rangeli </it>to vertebrate hosts. Recently, genomic resources for invertebrate vectors of human pathogens have increased significantly, and <it>R. prolixus </it>has been one of the main species studied among the triatomines. However, the paucity of information on many of the fundamental molecular aspects of this species limits the use of the available genomic information. The present study aimed to facilitate gene expression studies by identifying the most suitable reference genes for the normalization of mRNA expression data from qPCR.</p> <p>Results</p> <p>The expression stability of five candidate reference genes (<it>18S </it>rRNA, <it>GAPDH</it>, β-actin, α-tubulin and ribosomal protein <it>L26</it>) was evaluated by qPCR in two tissues (salivary gland and intestine) and under different physiological conditions: before and after blood feeding and after infection with <it>T. cruzi </it>or <it>T. rangeli</it>. The results were analyzed with three software programs: geNorm, NormFinder and BestKeeper. All of the evaluated candidate genes proved to be acceptable as reference genes, but some were found to be more appropriate depending on the experimental conditions. <it>18S</it>, <it>GAPDH </it>and α-tubulin showed acceptable stability for studies in all of the tissues and experimental conditions evaluated. β-actin, one of the most widely used reference genes, was confirmed to be one of the most suitable reference genes in studies with salivary glands, but it had the lowest expression stability in the intestine after insect blood feeding. <it>L26 </it>was identified as the poorest reference gene in the studies performed.</p> <p>Conclusions</p> <p>The expression stability of the genes varies in different tissue samples and under different experimental conditions. The results provided by three statistical packages emphasize the suitability of all five of the tested reference genes in both the crop and the salivary glands with a few exceptions. The results emphasise the importance of validating reference genes for qRT-PCR analysis in <it>R. prolixus </it>studies.</p

BioSimulators: a central registry of simulation engines and services for recommending specific tools

Computational models have great potential to accelerate bioscience, bioengineering, and medicine. However, it remains challenging to reproduce and reuse simulations, in part, because the numerous formats and methods for simulating various subsystems and scales remain siloed by different software tools. For example, each tool must be executed through a distinct interface. To help investigators find and use simulation tools, we developed BioSimulators (https://biosimulators.org), a central registry of the capabilities of simulation tools and consistent Python, command-line and containerized interfaces to each version of each tool. The foundation of BioSimulators is standards, such as CellML, SBML, SED-ML and the COMBINE archive format, and validation tools for simulation projects and simulation tools that ensure these standards are used consistently. To help modelers find tools for particular projects, we have also used the registry to develop recommendation services. We anticipate that BioSimulators will help modelers exchange, reproduce, and combine simulations

The study of atmospheric ice-nucleating particles via microfluidically generated droplets

Ice-nucleating particles (INPs) play a significant role in the climate and hydrological cycle by triggering ice formation in supercooled clouds, thereby causing precipitation and affecting cloud lifetimes and their radiative properties. However, despite their importance, INP often comprise only 1 in 10³–10⁶ ambient particles, making it difficult to ascertain and predict their type, source, and concentration. The typical techniques for quantifying INP concentrations tend to be highly labour-intensive, suffer from poor time resolution, or are limited in sensitivity to low concentrations. Here, we present the application of microfluidic devices to the study of atmospheric INPs via the simple and rapid production of monodisperse droplets and their subsequent freezing on a cold stage. This device offers the potential for the testing of INP concentrations in aqueous samples with high sensitivity and high counting statistics. Various INPs were tested for validation of the platform, including mineral dust and biological species, with results compared to literature values. We also describe a methodology for sampling atmospheric aerosol in a manner that minimises sampling biases and which is compatible with the microfluidic device. We present results for INP concentrations in air sampled during two field campaigns: (1) from a rural location in the UK and (2) during the UK’s annual Bonfire Night festival. These initial results will provide a route for deployment of the microfluidic platform for the study and quantification of INPs in upcoming field campaigns around the globe, while providing a benchmark for future lab-on-a-chip-based INP studies