3,379 research outputs found
Genetic Variation in Resistance of Scotch Pine to Zimmerman Pine Moth
(excerpt)
Scotch pine (Pinus sylvestris L.), a forest tree introduced from Eurasia, is commonly planted for Christmas tree and timber use in northeastern United States. In this country it has numerous insect enemies. Among the most important are European pine shoot moth, Rhyacionia buoliana (Schiffermiieller); pine root collar weevil, Hylobius radicis Buchanan;,European pine sawfly, Neodiprion sertifer (Geoffroy); and eastern white-pine shoot borer, Eucosma gloriola Heinrich. Previous studies (Wright et al., 1967; Wright and Wilson, 1972; Steiner, 1974) have revealed large genetic differences in resistance to some of these pests.
Another destructive pest is the Zimmerman pine moth, Dioryctria zimmermani (Grote). In 1968 this insect, native to the United States, was found attacking trees in a Scotch pine provenance test in southwestern Michigan. The attack rate was heavy and by 1973 it was obvious that some rams or varieties were attacked more heavily than others. This is a report on those differences
Regional Economic Implications of Water Allocation and Reliability
The understanding of how allocation decisions can maximise the economic returns to the community from water for irrigation has received little attention, but is a significant issue for regional councils, those interested in water allocation policy development, and for irrigated farmers. There is a tradeoff between the amount of irrigated area and the reliability with which it can be undertaken. Overseas studies have generated a curve with optimum levels of allocation which maximise the economic return to the community from the resource. The study on which this paper is based used a single case study to model the individual and regional economic outcomes for four scenarios of water allocation, using daily time step simulation models of the hydrological, irrigation, farm and financial systems over the 1973 – 2000 period. The results show that there is an increasing return to the region as the allocation from the resource increases, at the expense of lower returns to existing users.Irrigation, reliability, regional economic impacts, Agribusiness, Agricultural and Food Policy, Agricultural Finance, Community/Rural/Urban Development, Environmental Economics and Policy, Farm Management, Financial Economics, Institutional and Behavioral Economics, Land Economics/Use, Resource /Energy Economics and Policy,
Conformational Preferences of cis-1,3-Cyclopentanedicarboxylic Acid and Its Salts by ^1H NMR Spectroscopy: Energetics of Intramolecular Hydrogen Bonds in DMSO
The conformational populations of cis-1,3-
cyclopentanedicarboxylic acid (1) and its mono- and dianion
were established in DMSO solution by comparing the vicinal
proton−proton coupling constants (^3JHH) obtained in solution to their theoretical counterparts. Geometries used for ^3JHH theoretical estimation (using Karplus-type equations) were obtained from optimized structures at the B3LYP/6-31G-(2d,2p) level. The diacid (1) adopted many conformations, whereas the ionized species (1A mono- and 1B dianion) assumed single conformations. A downfield chemical shift of 19.45 ppm (Δδ_H = 7.43 ppm) observed at −60 °C was indicative of intramolecular hydrogen bonding in 1A, which was later corroborated by determining the ratio of the first (K_1) to the second (K_2) ionization constants. K_1/K_2 in DMSO (1.3 × 10^7) was significantly larger than the value in water (2 × 10). In addition, K_1/K_E = 200 (where K_E is the acidity constant of the monomethylester of 1) was greater than the intramolecular hydrogen bonding threshold value of 2. The calculated intramolecular hydrogen bond strength of 1A was ∼3.1 kcal mol^(−1), which is ∼2.7 kcal mol^(−1) more stable than the values for cis-
1,3-cyclohexanedicarboxylic acid (2A). Thus, the relative energies of intramolecular hydrogen bonding in the monoanions 1A and 2A suggests that 1,3-diaxial conformers are more favored for cyclopentane than for cyclohexane rings
Development of Advanced High Lift Leading Edge Technology for Laminar Flow Wings
This paper describes the Advanced High Lift Leading Edge (AHLLE) task performed by Northrop Grumman Systems Corporation, Aerospace Systems (NGAS) for the NASA Subsonic Fixed Wing project in an effort to develop enabling high-lift technology for laminar flow wings. Based on a known laminar cruise airfoil that incorporated an NGAS-developed integrated slot design, this effort involved using Computational Fluid Dynamics (CFD) analysis and quality function deployment (QFD) analysis on several leading edge concepts, and subsequently down-selected to two blown leading-edge concepts for testing. A 7-foot-span AHLLE airfoil model was designed and fabricated at NGAS and then tested at the NGAS 7 x 10 Low Speed Wind Tunnel in Hawthorne, CA. The model configurations tested included: baseline, deflected trailing edge, blown deflected trailing edge, blown leading edge, morphed leading edge, and blown/morphed leading edge. A successful demonstration of high lift leading edge technology was achieved, and the target goals for improved lift were exceeded by 30% with a maximum section lift coefficient (Cl) of 5.2. Maximum incremental section lift coefficients ( Cl) of 3.5 and 3.1 were achieved for a blown drooped (morphed) leading edge concept and a non-drooped leading edge blowing concept, respectively. The most effective AHLLE design yielded an estimated 94% lift improvement over the conventional high lift Krueger flap configurations while providing laminar flow capability on the cruise configuration
V838 Monocerotis: the central star and its environment a decade after outburst
Aims. V838 Monocerotis erupted in 2002, brightened in a series of outbursts,
and eventually developed a spectacular light echo. A very red star emerged a
few months after the outburst. The whole event has been interpreted as the
result of a merger. Methods. We obtained near-IR and mid-IR interferometric
observations of V838 Mon with the AMBER and MIDI recombiners located at the
Very Large Telescope Interferometer (VLTI) array. The MIDI two-beam
observations were obtained with the 8m Unit Telescopes between October 2011 and
February 2012. The AMBER three-beam observations were obtained with the compact
array (Bm) in April 2013 and the long array (B140m) in May 2014,
using the 1.8m Auxiliary Telescopes. Results. A significant new result is the
detection of a compact structure around V838 Mon, as seen from MIDI data. The
extension of the structure increases from a FWHM of 25 mas at 8 {\mu}m to 70
mas at 13 {\mu}m. At the adopted distance of D = 6.1 0.6 kpc, the dust is
distributed from about 150 to 400 AU around V838 Mon. The MIDI visibilities
reveal a flattened structure whose aspect ratio increases with wavelength. The
major axis is roughly oriented around a position angle of -10 degrees, which
aligns with previous polarimetric studies reported in the literature. This
flattening can be interpreted as a relic of the 2002 eruption or by the
influence of the currently embedded B3V companion. The AMBER data provide a new
diameter for the pseudo-photosphere, which shows that its diameter has
decreased by about 40% in 10yrs, reaching a radius R = 750 200
R (3.5 1.0 AU). Conclusions. After the 2002 eruption,
interpreted as the merging of two stars, it seems that the resulting source is
relaxing to a normal state. The nearby environment exhibits an equatorial
over-density of dust up to several hundreds of AU.Comment: Astronomy and Astrophysics (2014) Will be set by the publishe
Hierarchical Star Formation in Nearby LEGUS Galaxies
Hierarchical structure in ultraviolet images of 12 late-type LEGUS galaxies
is studied by determining the numbers and fluxes of nested regions as a
function of size from ~1 to ~200 pc, and the number as a function of flux. Two
starburst dwarfs, NGC 1705 and NGC 5253, have steeper number-size and flux-size
distributions than the others, indicating high fractions of the projected areas
filled with star formation. Nine subregions in 7 galaxies have similarly steep
number-size slopes, even when the whole galaxies have shallower slopes. The
results suggest that hierarchically structured star-forming regions several
hundred parsecs or larger represent common unit structures. Small galaxies
dominated by only a few of these units tend to be starbursts. The
self-similarity of young stellar structures down to parsec scales suggests that
star clusters form in the densest parts of a turbulent medium that also forms
loose stellar groupings on larger scales. The presence of super star clusters
in two of our starburst dwarfs would follow from the observed structure if
cloud and stellar subregions more readily coalesce when self-gravity in the
unit cell contributes more to the total gravitational potential.Comment: 9 pages, 4 figures, accepted for ApJ
Spectroscopic Characteristics of Carbon Dots (C-Dots) Derived from Carbon Fibers and Conversion to Sulfur-Bridged C-Dots Nanosheets
We synthesized sub‐10 nm carbon nanoparticles (CNPs) consistent with photoluminescent carbon dots (C-dots) from carbon fiber starting material. The production of different C-dots fractions was monitored over seven days. During the course of the reaction, one fraction of C-dots species with relatively high photoluminescence was short-lived, emerging during the first hour of reaction but disappearing after one day of reaction. Isolation of this species during the first hour of the reaction was crucial to obtaining higher-luminescent C-dots species. When the reaction proceeded for one week, the appearance of larger nanostructures was observed over time, with lateral dimensions approaching 200 nm. The experimental evidence suggests that these larger species are formed from small C-dot nanoparticles bridged together by sulfur-based moieties between the C-dot edge groups, as if the C-dots polymerized by cross-linking the edge groups through sulfur bridges. Their size can be tailored by controlling the reaction time. Our results highlight the variety of CNP products, from sub‐10 nm C-dots to ~200 nm sulfur-containing carbon nanostructures, that can be produced over time during the oxidation reaction of the graphenic starting material. Our work provides a clear understanding of when to stop the oxidation reaction during the top-down production of C-dots to obtain highly photoluminescent species or a target average particle size
MitoNeoD:a mitochondria-targeted superoxide probe
Mitochondrial superoxide (O2⋅−) underlies much oxidative damage and redox signaling. Fluorescent probes can detect O2⋅−, but are of limited applicability in vivo, while in cells their usefulness is constrained by side reactions and DNA intercalation. To overcome these limitations, we developed a dual-purpose mitochondrial O2⋅− probe, MitoNeoD, which can assess O2⋅− changes in vivo by mass spectrometry and in vitro by fluorescence. MitoNeoD comprises a O2⋅−-sensitive reduced phenanthridinium moiety modified to prevent DNA intercalation, as well as a carbon-deuterium bond to enhance its selectivity for O2⋅− over non-specific oxidation, and a triphenylphosphonium lipophilic cation moiety leading to the rapid accumulation within mitochondria. We demonstrated that MitoNeoD was a versatile and robust probe to assess changes in mitochondrial O2⋅− from isolated mitochondria to animal models, thus offering a way to examine the many roles of mitochondrial O2⋅−production in health and disease
- …
