Virtual Reality Wand Design and Fabrication

As virtual reality (VR) is becoming a more viable option for real world skills training, developers are attempting to uncover the methods and technologies that will lead to the most efficient transfer of knowledge and proficiency of the target tasks. Within these optimization issues lies the question that asks what type of VR interaction device will provide users with maximum control within the virtual environment (VE) while being a convenient and comfortable tool to use. An ideal interaction device should balance the factors of functionality, user satisfaction, and cost while yielding a well-designed product in the process. Although the needs for all VR systems are not the same, popular interaction devices in use today include wired gloves as well as VR wands, the current mode of interaction for study during this summer REU ISR project

Dust detection by the wave instrument on STEREO: nanoparticles picked up by the solar wind?

The STEREO/WAVES instrument has detected a very large number of intense voltage pulses. We suggest that these events are produced by impact ionisation of nanoparticles striking the spacecraft at a velocity of the order of magnitude of the solar wind speed. Nanoparticles, which are half-way between micron-sized dust and atomic ions, have such a large charge-to-mass ratio that the electric field induced by the solar wind magnetic field accelerates them very efficiently. Since the voltage produced by dust impacts increases very fast with speed, such nanoparticles produce signals as high as do much larger grains of smaller speeds. The flux of 10-nm radius grains inferred in this way is compatible with the interplanetary dust flux model. The present results may represent the first detection of fast nanoparticles in interplanetary space near Earth orbit.Comment: In press in Solar Physics, 13 pages, 5 figure

Constraining long-term denudation and faulting history in intraplate regions by multisystem thermochronology: An example of the Sudetic Marginal Fault (Bohemian Massif, central Europe)

The Rychlebské hory Mountain region in the Sudetes (NE Bohemian Massif) provides a natural laboratory for studies of postorogenic landscape evolution. This work reveals both the exhumation history of the region and the paleoactivity along the Sudetic Marginal Fault (SMF) using zircon (U-Th)/He (ZHe), apatite fission track (AFT), and apatite (U-Th)/He (AHe) dating of crystalline basement and postorogenic sedimentary samples. Most significantly, and in direct contradiction of traditional paleogeographic reconstructions, this work has found evidence of a large Cretaceous sea and regional burial (to >6.5 km) of the Carboniferous-Permian basement in the Late Cretaceous (~95–80 Ma). During the burial by sediments of the Bohemian Cretaceous Basin System, the SMF acted as a normal fault as documented by offset ZHe ages across the fault. At 85–70 Ma, the basin was inverted, Cretaceous strata eroded, and basement blocks were exhumed to the near surface at a rate of ~300 m/Ma as evidenced by Late Cretaceous–Paleocene AFT ages and thermal modeling results. There is no appreciable difference in AFT and AHe ages across the fault, suggesting that the SMF acted as a reverse fault during exhumation. In the late Eocene–Oligocene, the basement was locally heated to <70°C by magmatic activity related to opening of the Eger rift system. Neogene or younger thermal activity was not recorded in the thermochronological data, confirming that late Cenozoic uplift and erosion of the basement blocks was limited to less than ∼1.5 km in the study area

U–Pb Zircon geochronology of the Cambro-Ordovician metagranites and metavolcanic rocks of central and NW Iberia

New U–Pb zircon data from metagranites and metavolcanic rocks of the Schist-Graywacke Complex Domain and the Schistose Domain of Galicia Tras-os-Montes Zone from central and NW Iberia contribute to constrain the timing of the Cambro-Ordovician magmatism from Central Iberian and Galicia Tras-os-Montes Zones which occurred between 498 and 462 Ma. The crystallization ages of the metagranites and metavolcanic rocks from the northern Schist-Graywacke Complex Domain are as follows: (a) in west Salamanca, 489 ± 5 Ma for Vitigudino, 486 ± 6 Ma for Fermoselle and 471 ± 7 Ma for Ledesma; (b) in northern Gredos, 498 ± 4 Ma for Castellanos, 492 ± 4 Ma for San Pelayo and 488 ± 3 Ma for Bercimuelle; (c) in Guadarrama, 490 ± 5 Ma for La Estacion I, 489 ± 9 Ma for La Canada, 484 ± 6 Ma for Vegas de Matute (leucocratic), 483 ± 6 Ma for El Cardoso, 482 ± 8 Ma for La Morcuera, 481 ± 9 Ma for Buitrago de Lozoya, 478 ± 7 Ma for La Hoya, 476 ± 5 Ma for Vegas de Matute (melanocratic), 475 ± 5 Ma for Riaza, 473 ± 8 Ma for La Estacion II and 462 ± 11 Ma for La Berzosa; and (d) in Toledo, 489 ± 7 Ma for Mohares and 480 ± 8 Ma for Polan. The crystallization ages of the metagranites from the Schistose Domain of Galicia Tras-os-Montes Zone are 497 ± 6 Ma for Laxe, 486 ± 8 Ma for San Mamede, 482 ± 7 Ma for Bangueses, 481 ± 5 Ma for Noia, 480 ± 10 for Rial de Sabucedo, 476 ± 9 Ma for Vilanova, 475 ± 6 Ma for Pontevedra, 470 ± 6 Ma for Cherpa and 462 ± 8 Ma for Bande.This magmatism is characterized by an average isotopic composition of (87Sr/86Sr)485Ma ≈ 0.712, (eNd)485Ma ≈ -4.1 and (TDM) ≈ 1.62 Ga, and a high zircon inheritance, composed of Ediacaran–Early Cambrian (65 %) and, to a lesser extent, Cryogenian, Tonian, Mesoproterozoic, Orosirian and Archean pre-magmatic cores. Combining our geochronological and isotopic data with others of similar rocks from the European Variscan Belt, it may be deduced that Cambro-Ordovician magmas from this belt were mainly generated by partial melting of Ediacaran–Early Cambrian igneous rocks

Variscan multistage granitoid magmatism in Brunovistulicum: petrological and SHRIMP U-Pb zircon geochronological evidence from the southern part of the Strzelin Massif, SW Poland

U-Pb SHRIMP ages of one granodiorite and two tonalite samples from the Strzelin Massif, northern part of Brunovistulicum, reveal three distinct stages of Carboniferrous-early Permian granitoid magmatism: tonalitic I - 324 Ma, granodioritic - 305 Ma and tonalitic II/granitic - 295 Ma. The first stage of magmatism coincided with the first migmatization event which took place shortly after the first deformation. The second stage of granitoid plutonism was coeval with the second migmatization event which produced abundant pegmatites. It took place after compressional phases of the second deformation and was related to decompression at the beginning of tectonic denudation. The third, most abundant stage of magmatism was connected with late extension in that part of the Variscan Orogen

Exogenous seed treatment with proline and its consequences to Norway spruce (Picea abies (L.) H. Karst) seedling establishment

Accumulation of proline is a defense mechanism against external stress conditions, preventing damage to the structure and function of cells and improving plant development processes, such as germination. The purpose of this study was to investigate proline treatment as a means of improving the germination and development of Norway spruce seedlings. The effect of exogenous proline has been studied in three stages of initial plant development. The collected seeds were soaked in water or 8 mM proline solution and placed on the germinators. The germination capacity and the mean germination time were determined. Seedlings with radicles >10 mm were transferred to the sand-peat substrate at a constant temperature of 20 °C. Seedlings at 3 subsequent developmental stages (S1 – germinated seeds with radicles > 3 mm; S2 – seedlings with radicles >10 mm; S3 – established seedlings grown for 90 days) were examined for the oxygen consumption rate, total antioxidant capacity, hydrogen peroxide level, malondialdehyde level and intracellular proline content. Proline treatment was conducive to lowering the levels of hydrogen peroxide and malondialdehyde at stage S1. At the subsequent stages of development, the levels of hydrogen peroxide and malondialdehyde increased, and at the S3 stage, there was also a marked increase in total antioxidant capacity. At stage S3, the seedlings of the proline treatment were characterized by a lower total mass, and the response to exogenous proline was stronger in the root tissues than in the leaves. The oxygen consumption rate was higher for the proline treatment at all stages of development. Seedlings at the analyzed stages of establishment differed in response to proline treatment. Exogenous proline had some beneficial effects during the first phase of germination by reducing the level of hydrogen peroxide and improving the condition of lipid membranes. In the subsequent stages of seedling development, in response to the same concentration of proline solution, undesirable effects, such as an increase in hydrogen peroxide levels and damage to cytoplasmic membranes, were observed. Optimal concentrations of exogenous proline should be determined prior to commercial use of proline treatment to improve plant stress tolerance

Effects of spermidine on germination of Salix spp. after storage under controlled conditions

Willows produce fast germinating and short-lived seeds, difficult to store in the long-term under controlled conditions. The aim of this study was to examine the feasibility of storage of three Salix spp. at controlled temperatures (3°, −10°, −196 °C). We also analyzed the effect of spermidine (Spd) as an antioxidant factor in desiccated seeds. Collected seeds were either desiccated or hydrated to obtain 10 levels of moisture content (between app. 4% and 2%) and subjected to storage at temperatures 3°, −10°, or −196 °C (liquid nitrogen; LN). After two months, seeds were germinated on the light at 20 °C. Seeds desiccated below a safe range of moisture content were further tested and germinated on filter paper with additions of 0.25 mM Spd solution. After 7 days seedlings were examined for hydrogen peroxide content (H2O2) and total antioxidant capacity (TAC). Fresh seeds of three Salix species: Persian willow (S. aegyptiaca L.), heartleaf willow (S. cordata Michx.) and crack willow (S. ×fragilis L.) were successfully stored at temperature −10° and −196 °C for two months. After cryopreservation seed of S. aegyptiaca, S. cordata, and S. ×fragilis germinated without viability loss in moisture content ranging from 4.4–15.9%, 6.4–18.5%, and 7.1–11.5% respectively. The addition of Spd during germination of desiccated seed did not affect germination capacity. However, seedlings of S. aegyptiaca had lower hydrogen peroxide content in comparison with control (germination on water). Seedlings of S. cordata showed an increase in hydrogen peroxide content in control after storing in LN. In seedlings of Crack willow Spd increased hydrogen peroxide content. Seeds of tested species differ in response to storage conditions. Salix seeds can be stored successfully for two months at −10° or −196 °C without losing viability in the safe range of moisture content. Storing at 3 °C can be used for storage in the narrower range of seeds’ moisture content, however, seedlings stored at this temperature produce a higher level of reactive oxygen species. Germinating seeds in Spd did not increase their germination, however in S. aegyptiaca and S. cordata decreased hydrogen peroxide content

Population mobility and lithic tool diversity in the Late Gravettian – The case study of Lubná VI (Bohemian Massif)

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordThis paper presents the results of excavations conducted at the Late Gravettian site of Lubná VI in 2012 and 2018. This site is an exceptional example of a short-term Late Gravettian campsite, occupied between 27.5 and 27.1 ka cal BP. Due to the specific location of this site, in an area situated far from lithic raw material sources, the archaeological remains offer a rare possibility to understand the subsistence strategy of highly mobile hunter-gatherers in the Late Pleistocene. The knapped lithic assemblage is composed of erratic Cretaceous flint imported over long distances, and the tool inventory is typical of Late Gravettian assemblages from Central Europe, with a dominance of burins and backed implements. However, the lack of chert and flint raw material in the vicinity of the site inspired the occupants to use bladelet blanks to make hunting weaponry from burin spalls. This specific behaviour is unique among Gravettian inventories known from the western Carpathians. Reindeer dominate the faunal assemblage over other species. The season of occupation at Lubná VI was probably early autumn, and may be associated with the maximum use of environmental resources by the hunter-gatherers. The small campsite was located at a convenient spot for processing reindeer carcasses, where some hearth stone constructions were arranged. Because there was no woody vegetation in the closest vicinity of the site, reindeer bones and fat were used as fuel in hearths. Given the lack of nearby flint raw materials, the accessibility of large numbers of reindeer near Lubná, probably present on a seasonal basis, explains the occurrence of Late Gravettian occupation in this micro-region.National Science Center, PolandMinistry for Innovation and TechnologyHungarian Academy of Sciences (MTA