Advanced stratified charge rotary aircraft engine design study

A technology base of new developments which offered potential benefits to a general aviation engine was compiled and ranked. Using design approaches selected from the ranked list, conceptual design studies were performed of an advanced and a highly advanced engine sized to provide 186/250 shaft Kw/HP under cruise conditions at 7620/25,000 m/ft altitude. These are turbocharged, direct-injected stratified charge engines intended for commercial introduction in the early 1990's. The engine descriptive data includes tables, curves, and drawings depicting configuration, performance, weights and sizes, heat rejection, ignition and fuel injection system descriptions, maintenance requirements, and scaling data for varying power. An engine-airframe integration study of the resulting engines in advanced airframes was performed on a comparative basis with current production type engines. The results show airplane performance, costs, noise & installation factors. The rotary-engined airplanes display substantial improvements over the baseline, including 30 to 35% lower fuel usage

The Agricultural Matrix and a Future Paradigm for Conservation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73889/1/j.1523-1739.2006.00582.x.pd

Yield and Economic Performance of Organic and Conventional Cotton-Based Farming Systems – Results from a Field Trial in India

The debate on the relative benefits of conventional and organic farming systems has in recent time gained significant interest. So far, global agricultural development has focused on increased productivity rather than on a holistic natural resource management for food security. Thus, developing more sustainable farming practices on a large scale is of utmost importance. However, information concerning the performance of farming systems under organic and conventional management in tropical and subtropical regions is scarce. This study presents agronomic and economic data from the conversion phase (2007–2010) of a farming systems comparison trial on a Vertisol soil in Madhya Pradesh, central India. A cotton-soybean-wheat crop rotation under biodynamic, organic and conventional (with and without Bt cotton) management was investigated. We observed a significant yield gap between organic and conventional farming systems in the 1st crop cycle (cycle 1: 2007–2008) for cotton (229%) and wheat (227%), whereas in the 2nd crop cycle (cycle 2: 2009–2010) cotton and wheat yields were similar in all farming systems due to lower yields in the conventional systems. In contrast, organic soybean (a nitrogen fixing leguminous plant) yields were marginally lower than conventional yields (21% in cycle 1, 211% in cycle 2). Averaged across all crops, conventional farming systems achieved significantly higher gross margins in cycle 1 (+29%), whereas in cycle 2 gross margins in organic farming systems were significantly higher (+25%) due to lower variable production costs but similar yields. Soybean gross margin was significantly higher in the organic system (+11%) across the four harvest years compared to the conventional systems. Our results suggest that organic soybean production is a viable option for smallholder farmers under the prevailing semi-arid conditions in India. Future research needs to elucidate the long-term productivity and profitability, particularly of cotton and wheat, and the ecological impact of the different farming systems

Measurement of the Positive Muon Anomalous Magnetic Moment to 0.20 ppm

We present a new measurement of the positive muon magnetic anomaly, a_{μ}≡(g_{μ}-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, ω[over ˜]_{p}^{'}, and of the anomalous precession frequency corrected for beam dynamics effects, ω_{a}. From the ratio ω_{a}/ω[over ˜]_{p}^{'}, together with precisely determined external parameters, we determine a_{μ}=116 592 057(25)×10^{-11} (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a_{μ}(FNAL)=116 592 055(24)×10^{-11} (0.20 ppm). The new experimental world average is a_{μ}(exp)=116 592 059(22)×10^{-11} (0.19 ppm), which represents a factor of 2 improvement in precision

Cryptic Diversity of African Tigerfish (Genus Hydrocynus) Reveals Palaeogeographic Signatures of Linked Neogene Geotectonic Events

The geobiotic history of landscapes can exhibit controls by tectonics over biotic evolution. This causal relationship positions ecologically specialized species as biotic indicators to decipher details of landscape evolution. Phylogeographic statistics that reconstruct spatio-temporal details of evolutionary histories of aquatic species, including fishes, can reveal key events of drainage evolution, notably where geochronological resolution is insufficient. Where geochronological resolution is insufficient, phylogeographic statistics that reconstruct spatio-temporal details of evolutionary histories of aquatic species, notably fishes, can reveal key events of drainage evolution. This study evaluates paleo-environmental causes of mitochondrial DNA (mtDNA) based phylogeographic records of tigerfishes, genus Hydrocynus, in order to reconstruct their evolutionary history in relation to landscape evolution across Africa. Strong geographical structuring in a cytochrome b (cyt-b) gene phylogeny confirms the established morphological diversity of Hydrocynus and reveals the existence of five previously unknown lineages, with Hydrocynus tanzaniae sister to a clade comprising three previously unknown lineages (Groups B, C and D) and H. vittatus. The dated phylogeny constrains the principal cladogenic events that have structured Hydrocynus diversity from the late Miocene to the Plio-Pleistocene (ca. 0–16 Ma). Phylogeographic tests reveal that the diversity and distribution of Hydrocynus reflects a complex history of vicariance and dispersals, whereby range expansions in particular species testify to changes to drainage basins. Principal divergence events in Hydrocynus have interfaced closely with evolving drainage systems across tropical Africa. Tigerfish evolution is attributed to dominant control by pulses of geotectonism across the African plate. Phylogenetic relationships and divergence estimates among the ten mtDNA lineages illustrates where and when local tectonic events modified Africa's Neogene drainage. Haplotypes shared amongst extant Hydrocynus populations across northern Africa testify to recent dispersals that were facilitated by late Neogene connections across the Nilo-Sahelian drainage. These events in tigerfish evolution concur broadly with available geological evidence and reveal prominent control by the African Rift System, evident in the formative events archived in phylogeographic records of tigerfish

Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab

This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 dataset of the Fermilab Muon g-2 Experiment. Two corrections to the measured muon precession frequency ωam are associated with well-known effects owing to the use of electrostatic quadrupole (ESQ) vertical focusing in the storage ring. An average vertically oriented motional magnetic field is felt by relativistic muons passing transversely through the radial electric field components created by the ESQ system. The correction depends on the stored momentum distribution and the tunes of the ring, which has relatively weak vertical focusing. Vertical betatron motions imply that the muons do not orbit the ring in a plane exactly orthogonal to the vertical magnetic field direction. A correction is necessary to account for an average pitch angle associated with their trajectories. A third small correction is necessary, because muons that escape the ring during the storage time are slightly biased in initial spin phase compared to the parent distribution. Finally, because two high-voltage resistors in the ESQ network had longer than designed RC time constants, the vertical and horizontal centroids and envelopes of the stored muon beam drifted slightly, but coherently, during each storage ring fill. This led to the discovery of an important phase-acceptance relationship that requires a correction. The sum of the corrections to ω_{a}^{m} is 0.50±0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of ω_{a}^{m}

Complex evolutionary history of the Mexican stoneroller Campostoma ornatum Girard, 1856 (Actinopterygii: Cyprinidae)

<p>Abstract</p> <p>Background</p> <p>Studies of the phylogeography of Mexican species are steadily revealing genetic patterns shared by different species, which will help to unravel the complex biogeographic history of the region. <it>Campostoma ornatum </it>is a freshwater fish endemic to montane and semiarid regions in northwest Mexico and southern Arizona. Its wide range of distribution and the previously observed morphological differentiation between populations in different watersheds make this species a useful model to investigate the biogeographic role of the Sierra Madre Occidental and to disentangle the actions of Pliocene tecto-volcanic processes <it>vs </it>Quaternary climatic change. Our phylogeographic study was based on DNA sequences from one mitochondrial gene (<it>cytb</it>, 1110 bp, n = 285) and two nuclear gene regions (S7 and RAG1, 1822 bp in total, n = 56 and 43, respectively) obtained from 18 to 29 localities, in addition to a morphological survey covering the entire distribution area. Such a dataset allowed us to assess whether any of the populations/lineages sampled deserve to be categorised as an evolutionarily significant unit.</p> <p>Results</p> <p>We found two morphologically and genetically well-differentiated groups within <it>C. ornatum</it>. One is located in the northern river drainages (Yaqui, Mayo, Fuerte, Sonora, Casas Grandes, Santa Clara and Conchos) and another one is found in the southern drainages (Nazas, Aguanaval and Piaxtla). The split between these two lineages took place about 3.9 Mya (CI = 2.1-5.9). Within the northern lineage, there was strong and significant inter-basin genetic differentiation and also several secondary dispersal episodes whit gene homogenization between drainages. Interestingly, three divergent mitochondrial lineages were found in sympatry in two northern localities from the Yaqui river basin.</p> <p>Conclusions</p> <p>Our results indicate that there was isolation between the northern and southern phylogroups since the Pliocene, which was related to the formation of the ancient Nazas River paleosystem, where the southern group originated. Within groups, a complex reticulate biogeographic history for <it>C. ornatum </it>populations emerges, following the taxon pulse theory and mainly related with Pliocene tecto-volcanic processes. In the northern group, several events of vicariance promoted by river or drainage isolation episodes were found, but within both groups, the phylogeographic patterns suggest the occurrence of several events of river capture and fauna interchange. The Yaqui River supports the most diverse populations of <it>C. ornatum</it>, with several events of dispersal and isolation within the basin. Based on our genetic results, we defined three ESUs within <it>C. ornatum </it>as a first attempt to promote the conservation of the evolutionary processes determining the genetic diversity of this species. They will likely be revealed as a valuable tool for freshwater conservation policies in northwest Mexico, where many environmental problems concerning the use of water have rapidly arisen in recent decades.</p