289 research outputs found

    Geochronological and geochemical characteristics of the Dehzaman intrusive and volcanic rocks (NE Iran): Implication for a Cadomian magmatism

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    Cadomian magmatism is interpreted to indicate fragments of late Neoproterozoic-Early Cambrian continental arcs bordering the northern margin of Gondwana. Cadomian rocks constitute the main elements of the continental crust of central Iranian block (including the Lut block). An example of such Cadomian rocks from NE Iran is studied here: the Dehzaman igneous rocks within the Kashmar- Kerman Tectonic Zone (KKTZ). The Cadomian exposure in NE Iran includes intrusive rocks with a thick sequence of felsic volcanic rocks. Zircon U-Pb dating of syenogranites and ryholites yielded 238U/206Pb crystallization ages of ≈521.3 to ≈524.3 Ma, respectively and the age of 557 Ma to Biosyenogranites already was obtained by Rossetti et al. (2015) (Ediacaran-Early Cambrian). Geochemically, the intrusive rocks are mostly characterized by high-K content and are similar to the I-type granites. These rocks are characterized by enrichment in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) along with depletion in high field strength elements (HFSEs). Their initial ΔNd (t) ranges from -0.6 to -2.1 at 86Sr/87Sr (i)=0.7045-0.7073. The Cadomian rocks from NE Iran, along with similaraged rocks from Turkey and Iran are suggested to form in an early stage of an active continental margin.publishe

    Multi-Domain Cognitive Assessment of Male Mice Shows Space Radiation Is Not Harmful to High-Level Cognition and Actually Improves Pattern Separation

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    Astronauts on interplanetary missions - such as to Mars - will be exposed to space radiation, a spectrum of highly-charged, fast-moving particles that includes 56Fe and 28Si. Earth-based preclinical studies show space radiation decreases rodent performance in low- and some high-level cognitive tasks. Given astronaut use of touchscreen platforms during training and space flight and given the ability of rodent touchscreen tasks to assess functional integrity of brain circuits and multiple cognitive domains in a non-aversive way, here we exposed 6-month-old C57BL/6J male mice to whole-body space radiation and subsequently assessed them on a touchscreen battery. Relative to Sham treatment, 56Fe irradiation did not overtly change performance on tasks of visual discrimination, reversal learning, rule-based, or object-spatial paired associates learning, suggesting preserved functional integrity of supporting brain circuits. Surprisingly, 56Fe irradiation improved performance on a dentate gyrus-reliant pattern separation task; irradiated mice learned faster and were more accurate than controls. Improved pattern separation performance did not appear to be touchscreen-, radiation particle-, or neurogenesis-dependent, as 56Fe and 28Si irradiation led to faster context discrimination in a non-touchscreen task and 56Fe decreased new dentate gyrus neurons relative to Sham. These data urge revisitation of the broadly-held view that space radiation is detrimental to cognition

    The tropical managed forests observatory: a research network addressing the future of tropical logged forests.

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    While attention on logging in the tropics has been increasing, studies on the long-term effects of silviculture on forest dynamics and ecology remain scare and spatially limited. Indeed, most of our knowledge on tropical forests arises from studies carried out in undisturbed tropical forests. This biasis problematic given that logged and disturbed tropical forests are now covering a larger area thantheso-alled primary forests. A new network of permanent sample plots in logged forests, the Tropical managed Forests Observatory (TmFO), aims to ?ll this gap by providing unprecedented opportunities to examine long-term data on the resilience of logged tropical forests at regional and global scales. TmFO currently includes 24 experimental sites distributed across three tropical regions, with a total of 490 permanent plots and 921 ha of forest inventories

    Understanding earthquake hazards in southern California - the "LARSE" project - working toward a safer future for Los Angeles

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    The Los Angeles region is underlain by a network of active faults, including many that are deep and do not break the Earth’s surface. These hidden faults include the previously unknown one responsible for the devastating January 1994 Northridge earthquake, the costliest quake in U.S. history. So that structures can be built or strengthened to withstand the quakes that are certain in the future, the Los Angeles Region Seismic Experiment (LARSE) is locating hidden earthquake hazards beneath the region to help scientists determine where the strongest shaking will occur

    Comparison of the efficacy of four drug combinations for immobilization of wild pigs

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    Field immobilization of native or invasive wild pigs (Sus scrofa) is challenging. Drug combinations commonly used often result in unsatisfactory immobilization, poor recovery, and adverse side effects, leading to unsafe handling conditions for both animals and humans. We compared four chemical immobilization combinations, medetomidine–midazolam–butorphanol (MMB), butorphanol–azaperone–medetomidine (BAMℱ), nalbuphine–medetomidine–azaperone (NalMed-A), and tiletamine– zolazepam–xylazine (TZX), to determine which drug combinations might provide better chemical immobilization of wild pigs. We achieved adequate immobilization with no post-recovery morbidity withMMB. Adequate immobilization was achieved with BAMℱ; however, we observed post-recovery morbidity. Both MMB and BAMℱ produced more optimal results relative to body temperature, recovery, and post-recovery morbidity and mortality compared to TZX. Adequate immobilization was not achieved with NalMed-A. Of the four drug combinations examined, we conclude that MMB performed most optimally for immobilization and recovery of wild pigs

    Alcohol policy enforcement and changes in student drinking rates in a statewide public college system: a follow-up study

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    <p>Abstract</p> <p>Background</p> <p>Heavy alcohol use among U.S. college students is a major contributor to young adult morbidity and mortality. The aim of this study was to examine whether college alcohol policy enforcement levels predict changes in student drinking and related behaviors in a state system of public colleges and universities, following a system-wide change to a stricter policy.</p> <p>Methods</p> <p>Students and administrators at 11 Massachusetts public colleges/universities completed surveys in 1999 (N of students = 1252), one year after the policy change, and again in 2001 (N = 1074). We calculated policy enforcement scores for each school based on the reports of deans of students, campus security chiefs, and students, and examined the correlations between perceived enforcement levels and the change in student drinking rates over the subsequent two year period, after weighting the 2001 data to adjust for demographic changes in the student body.</p> <p>Results</p> <p>Overall rates of any past-30-days drinking, heavy episodic drinking, and usual heavy drinking among past-30-days drinkers were all lower in 2001 compared to 1999. School-level analyses (N = 11) found deans' baseline reports of stricter enforcement were strongly correlated with subsequent declines in heavy episodic drinking (Pearson's r = -0.73, p = 0.011). Moreover, consistently high enforcement levels across time, as reported by deans, were associated with greater declines in heavy episodic drinking. Such relationships were not found for students' and security chiefs' reports of enforcement. Marijuana use did not rise during this period of decline in heavy drinking.</p> <p>Conclusions</p> <p>Study findings suggest that stronger enforcement of a stricter alcohol policy may be associated with reductions in student heavy drinking rates over time. An aggressive enforcement stance by deans may be an important element of an effective college alcohol policy.</p

    Unusual shock-excited oh maser emission in a young Planetary Nebula

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    © 2016. The American Astronomical Society. All rights reserved. We report on OH maser emission toward G336.644-0.695 (IRAS 16333-4807), which is a H2O maser-emitting Planetary Nebula (PN). We have detected 1612, 1667, and 1720 MHz OH masers at two epochs using the Australia Telescope Compact Array, hereby confirming it as the seventh known case of an OH-maser-emitting PN. This is only the second known PN showing 1720 MHz OH masers after K 3-35 and the only evolved stellar object with 1720 MHz OH masers as the strongest transition. This PN is one of a group of very young PNe. The 1612 MHz and 1667 MHz masers are at a similar velocity to the 22 GHz H2O masers, whereas the 1720 MHz masers show a variable spectrum, with several components spread over a higher velocity range (up to 36 km s-1). We also detect Zeeman splitting in the 1720 MHz transition at two epochs (with field strengths of ~2 to ~10 mG), which suggests the OH emission at 1720 MHz is formed in a magnetized environment. These 1720 MHz OH masers may trace short-lived equatorial ejections during the formation of the PN

    Accurate OH maser positions from the SPLASH pilot region

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    We report on high spatial resolution observations, using the Australia Telescope Compact Array (ATCA), of ground-state OH masers. These observations were carried out toward 196 pointing centers previously identified in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) pilot region, between Galactic longitudes of 334 and 344 and Galactic latitudes of -2 and +2. Supplementing our data with data from the MAGMO (Mapping the Galactic Magnetic field through OH masers) survey, we find maser emission toward 175 of the 196 target fields. We conclude that about half of the 21 nondetections were due to intrinsic variability. Due to the superior sensitivity of the followup ATCA observations, and the ability to resolve nearby sources into separate sites, we have identified 215 OH maser sites toward the 175 fields with detections. Among these 215 OH maser sites, 111 are new detections. After comparing the positions of these 215 maser sites to the literature, we identify 122 (57%) sites associated with evolved stars (one of which is a planetary nebula), 64 (30%) with star formation, two sites with supernova remnants, and 27 (13%) of unknown origin. The infrared colors of evolved star sites with symmetric maser profiles tend to be redder than those of evolved star sites with asymmetric maser profiles, which may indicate that symmetric sources are generally at an earlier evolutionary stage. © 2016. The American Astronomical Society. All rights reserved
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