1,493 research outputs found
Why legal cannabis may be more widespread in the US after the election.
The process of implementing comprehensive cannabis legislation varies between states and is often met with bureaucratic challenges. With many states putting medical and recreational cannabis on the ballot this election, Lee Hannah, Gideon Cunningham and Daniel Mallinson look at the key differences in these states’ approaches to legalisation. The increasing momentum on legal cannabis, they write, is likely to put further pressure on Congress to pass national cannabis policy reform
Stratosphere-troposphere separation of nitrogen dioxide columns from the TEMPO geostationary satellite instrument
Separating the stratospheric and tropospheric contributions in satellite retrievals of atmospheric NO2 column abundance is a crucial step in the interpretation and application of the satellite observations. A variety of stratosphere–troposphere separation algorithms have been developed for sun-synchronous instruments in low Earth orbit (LEO) that benefit from global coverage, including broad clean regions with negligible tropospheric NO2 compared to stratospheric NO2. These global sun-synchronous algorithms need to be evaluated and refined for forthcoming geostationary instruments focused on continental regions, which lack this global context and require hourly estimates of the stratospheric column. Here we develop and assess a spatial filtering algorithm for the upcoming TEMPO geostationary instrument that will target North America. Developments include using independent satellite observations to identify likely locations of tropospheric enhancements, using independent LEO observations for spatial context, consideration of diurnally varying partial fields of regard, and a filter based on stratospheric to tropospheric air mass factor ratios. We test the algorithm with LEO observations from the OMI instrument with an afternoon overpass, and from the GOME-2 instrument with a morning overpass.
We compare our TEMPO field of regard algorithm against an identical global algorithm to investigate the penalty resulting from the limited spatial coverage in geostationary orbit, and find excellent agreement in the estimated mean daily tropospheric NO2 column densities (R2=0.999, slope=1.009 for July and R2=0.998, slope=0.999 for January). The algorithm performs well even when only small parts of the continent are observed by TEMPO. The algorithm is challenged the most by east coast morning retrievals in the wintertime (e.g., R2=0.995, slope=1.038 at 14:00 UTC). We find independent global LEO observations (corrected for time of day) provide important context near the field-of-regard edges. We also test the performance of the TEMPO algorithm without these supporting global observations. Most of the continent is unaffected (R2=0.924 and slope=0.973 for July and R2=0.996 and slope=1.008 for January), with 90 % of the pixels having differences of less than ±0.2×1015 molecules cm−2 between the TEMPO tropospheric NO2 column density and the global algorithm. For near-real-time retrieval, even a climatological estimate of the stratospheric NO2 surrounding the field of regard would improve this agreement. In general, the additional penalty of a limited field of regard from TEMPO introduces no more error than normally expected in most global stratosphere–troposphere separation algorithms. Overall, we conclude that hourly near-real-time stratosphere–troposphere separation for the retrieval of NO2 tropospheric column densities by the TEMPO geostationary instrument is both feasible and robust, regardless of the diurnally varying limited field of regard.The authors are grateful to Kelly Chance, Xiong Liu, John Houck, Peter Zoogman, and other members of the TEMPO trace gas retrieval team for their input in preparation of this paper. Work at Dalhousie University was supported by Environment and Climate Change Canada. The authors also gratefully acknowledge the free use of TEMIS NO2 data from the GOME-2 sensor provided by http://www.temis.nl, last access: 12 November 2018, and the NASA Standard Product NO2 data from OMI provided by https://disc.gsfc.nasa.gov/datasets/OMNO2_V003/summary, last access: 9 November 2018. (Environment and Climate Change Canada)https://www.atmos-meas-tech.net/11/6271/2018/Published versio
Sway, yaw, and roll coupling effects on straight line stability of submersibles
This thesis analyzes the sway, yaw, and roll dynamic stability of neutrally
buoyant submersibles. Utilizing the hydrodynamic coefficients for a Mark
IX Swimmer Delivery Vehicle (SDV) as a base-line model, the linearized
equations of motion for the decoupled steering and roll systems are
compared to the coupled system. Two different configurations of
hydrodynamic coefficients are considered along with the effects of varying
the vertical (Zg ) and longitudinal (Xg) centers of gravity of the vehicle while
the longitudinal center of buoyancy (Xb) is held constant. Results
demonstrate the significant effects on stability of coupling the steering and
roll equations of motion, and the importance of Zg and Xg selection in
minimizing those effects while retaining stability. Perturbation analysis
results confirm the essential dependence of the linearized coupled
equations on the separation of Xg and Xb.http://archive.org/details/swayyawndrollcou1094524234Lieutenant, United States NavyApproved for public release; distribution is unlimited
Observation of Porosity Reduction in a Densification-Prone Test Fuel Rod: Data and Analysis
Instrumented fuel assembly (IFA)-431 was irradiated in the Halden Boiling Water Reactor (HBWR) for the purpose of extending the steady-state data base. Rod 6 of this assembly began irradiation with UO{sub 2} fuel of 92% theoretical density (TD) that was unstable with respect to in-reactor densification. Thermal resintering tests resulted in a final density of 95.3% TD while post-irradiation examination (PIE) indicated a final density of 96.5% TD. Observed microstructural changes were consistent with published densification studies; there was a marked depletion of submicrometer diameter pores and total pore volume. However, grain size increased only slightly, indicating that internal pellet temperatures did not reach the 1875K applied in resintering tests. Oensification was observed to increase the temperatures in rod 6, but temperatures did not become as high as for a sibling rod that simulated instantaneous densification. Temperatures calculated with U.S. Nuclear Regulatory Commission (NRC) fuel performance computer codes were generally higher than observed temperatures
Tactile bill-tip organs in seabirds suggest conservation of a deep avian symplesiomorphy
Birds’ bills are their main tactile interface with the outside world. Tactile bill-tip organs associated with specialized foraging techniques are present in several bird groups, yet remain understudied in most clades. One example is Austrodyptornithes, the major seabird clade uniting Procellariiformes (albatrosses and petrels) and Sphenisciformes (penguins). Here, we describe the mechanoreceptor arrangement and neurovascular anatomy in the premaxillae of Austrodyptornithes. Using a wide phylogenetic sample of extant birds (361 species), we show that albatrosses and penguins exhibit complex tactile bill-tip anatomies, comparable to birds with known bill-tip organs, despite not being known to use tactile foraging. Petrels (Procellariidae, Hydrobatidae and Oceanitidae) lack these morphologies, indicating an evolutionary transition in bill-tip mechanosensitivity within Procellariiformes. The bill-tip organ in Austrodyptornithes may be functionally related to nocturnal foraging and prey detection under water, or courtship displays involving tactile stimulation of the bill. Alternatively, these organs may be vestigial as is likely the case in most palaeognaths (e.g. ostriches and emu). Ancestral state reconstructions fail to reject the hypothesis that the last common ancestor of Austrodyptornithes had a bill-tip organ; thus, tactile foraging may be ancestral for this major extant clade, perhaps retained from a deeper point in crown bird evolutionary history.</jats:p
Measuring Recovery: An Adapted Brief Assessment of Mood (BAM+) Compared to Biochemical and Power Output Alterations
ObjectivesBiochemical (e.g., creatine kinase (CK)) and neuromuscular (e.g., peak power output (PPO)) markers of recovery are expensive and require specialist equipment. Perceptual measures are an effective alternative, yet most validated scales are too long for daily use.DesignThis study utilises a longitudinal multi-level design to test an adapted Brief Assessment of Mood (BAM + ), with four extra items and a 100 mm visual analogue scale to measure recovery.MethodsElite under-21 academy soccer players (N = 11) were monitored across five games with data (BAM+, CK and PPO) collected for each game at 24 hours pre, 24 hours and 48 hours post-match. Match activity data for each participant was also collected using GPS monitors on players.ResultsBAM+, CK and PPO had significant (p < .05) linear and quadratic growth curves across time and games that matched the known time reports of fatigue and recovery. Multi-level linear modelling (MLM) with random intercepts for ‘participant’ and ‘game’ indicated only CK significantly contributed to the variance of BAM+ scores (p < .05). Significant correlations (p < .01) were found between changes in BAM+ scores from baseline at 24 and 48 hours post-match for total distance covered per minute, high intensity distance covered per minute, and total number of sprints per minute.ConclusionsVisual and inferential results indicate that the BAM+ appears effective for monitoring longitudinal recovery cycles in elite level athletes. Future research is needed to confirm both the scales reliability and validity
Movement Demands of Elite Under-20s and Senior International Rugby Union Players
This study compared the movement demands of elite international Under-20 age grade (U20s) and senior international rugby union players during competitive tournament match play. Forty elite professional players from an U20 and 27 elite professional senior players from international performance squads were monitored using 10Hz global positioning systems (GPS) during 15 (U20s) and 8 (senior) international tournament matches during the 2014 and 2015 seasons. Data on distances, velocities, accelerations, decelerations, high metabolic load (HML) distance and efforts, and number of sprints were derived. Data files from players who played over 60 min (n = 258) were separated firstly into Forwards and Backs, and more specifically into six positional groups; FR–Front Row (prop & hooker), SR–Second Row, BR–Back Row (Flankers & No.8), HB–Half Backs (scrum half & outside half), MF–Midfield (centres), B3 –Back Three (wings & full back) for match analysis. Linear mixed models revealed significant differences between U20 and senior teams in both the forwards and backs. In the forwards the seniors covered greater HML distance (736.4 ± 280.3 vs 701.3 ± 198.7m, p = 0.01) and severe decelerations (2.38 ± 2.2 vs 2.28 ± 1.65, p = 0.05) compared to the U20s, but performed less relative HSR (3.1 ± 1.6 vs 3.2 ± 1.5, p < 0.01), moderate (19.4 ± 10.5 vs 23.6 ± 10.5, p = 0.01) and high accelerations (2.2 ± 1.9 vs 4.3 ± 2.7, p < 0.01) and sprint•min-1 (0.11 ± 0.06 vs 0.11 ± 0.05, p < 0.01). Senior backs covered a greater relative distance (73.3 ± 8.1 vs 69.1 ± 7.6 m•min-1, p < 0.01), greater High Metabolic Load (HML) distance (1138.0 ± 233.5 vs 1060.4 ± 218.1m, p < 0.01), HML efforts (112.7 ± 22.2 vs 98.8 ± 21.7, p < 0.01) and heavy decelerations (9.9 ± 4.3 vs 9.5 ± 4.4, p = 0.04) than the U20s backs. However, the U20s backs performed more relative HSR (7.3 ± 2.1 vs 7.2 ± 2.1, p <0.01) and sprint•min-1 (0.26 ± 0.07 vs 0.25 ± 0.07, p < 0.01). Further investigation highlighted differences between the 6 positional groups of the teams. The positional groups that differed the most on the variables measured were the FR and MF groups, with the U20s FR having higher outputs on HSR, moderate & high accelerations, moderate, high & severe decelerations, HML distance, HML efforts, and sprints•min-1. For the MF group the senior players produced greater values for relative distance covered, HSR, moderate decelerations, HML distance and sprint•min-1. The BR position group was most similar with the only differences seen on heavy accelerations (U20s higher) and moderate decelerations (seniors higher). Findings demonstrate that U20s internationals appear to be an adequate ‘stepping stone’ for preparing players for movement characteristics found senior International rugby, however, the current study highlight for the first time that certain positional groups may require more time to be able to match the movement demands required at a higher playing level than others. Conditioning staff must also bear in mind that the U20s players whilst maintaining or improving match movement capabilities may require to gain substantial mass in some positions to match their senior counterparts
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Selective nitrogen adsorption via backbonding in a metal-organic framework with exposed vanadium sites.
Industrial processes prominently feature π-acidic gases, and an adsorbent capable of selectively interacting with these molecules could enable important chemical separations1-4. Biological systems use accessible, reducing metal centres to bind and activate weakly π-acidic species, such as N2, through backbonding interactions5-7, and incorporating analogous moieties into a porous material should give rise to a similar adsorption mechanism for these gaseous substrates8. Here, we report a metal-organic framework featuring exposed vanadium(II) centres capable of back-donating electron density to weak π acids to successfully target π acidity for separation applications. This adsorption mechanism, together with a high concentration of available adsorption sites, results in record N2 capacities and selectivities for the removal of N2 from mixtures with CH4, while further enabling olefin/paraffin separations at elevated temperatures. Ultimately, incorporating such π-basic metal centres into porous materials offers a handle for capturing and activating key molecular species within next-generation adsorbents
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