Comparative Gas-Exchange in Leaves of Intact and Clipped, Natural and Planted Cherrybark Oak (Quercus pagoda Raf.) Seedlings

Gas-exchange measurements, including CO2 -exchange rate (net photosynthesis), stomatal conductance, and transpiration, were conducted on intact and clipped cherrybark oak (Quercus pagoda Raf.) seedlings growing in the field and in a nursery bed. Seedlings in the field, released from midstory and understory woody competition, showed significant increases in gas-exchange compared to non-released seedlings due to increases in light levels reaching seedlings. Concurrently, little difference occurred in the CO2 -exchange rate between intact and clipped seedlings in the released treatment although clipped seedlings maintained a consistently greater rate of stomatal conductance. In order to reduce the high variability of light levels recorded in the field, gas-exchange measurements were conducted on intact and clipped cherrybark oak seedlings growing in a nursery bed under consistent light conditions. Again, no differences were found in the CO2 - exchange rate between intact and clipped seedlings. Furthermore, no differences were found in stomatal conductance and transpiration between intact and clipped seedlings. However, significant differences in gas-exchange were found between first-flush and second-flush leaves regardless of seedling treatment (intact or a sprout). Greater rates of gas-exchange in second-flush leaves can be attributed to developing third-flush steams and leaves

Aging and aerobic fitness affect the contribution of noradrenergic sympathetic nerves to the rapid cutaneous vasodilator response to local heating

Sedentary aging results in a diminished rapid cutaneous vasodilator response to local heating. We investigated whether this diminished response was due to altered contributions of noradrenergic sympathetic nerves; assessing 1) the age-related decline and, 2) the effect of aerobic fitness. We measured skin blood flow (SkBF)(laser-Doppler flowmetry) in young (24±1 yr) and older (64±1 yr) endurance-trained and sedentary men (n=7 per group) at baseline and during 35 min of local skin heating to 42 °C at three forearm sites: 1) untreated; 2) bretylium tosylate (BT), preventing neurotransmitter release from noradrenergic sympathetic nerves; and 3) yohimbine and propranolol (YP), antagonising α- and β-adrenergic receptors. SkBF was converted to cutaneous vascular conductance (CVC) (SkBF/mean arterial pressure) and normalized to maximal CVC (%CVCmax) achieved by skin heating to 44 °C. Pharmacological agents were administered using microdialysis. In the young trained, the rapid vasodilator response was reduced at the BT and YP sites (P0.05) but treatment with BT did (P>0.05). Neither BT nor YP treatments affected the rapid vasodilator response in the older sedentary group (P>0.05). These data suggest that the age-related reduction in the rapid vasodilator response is due to an impairment of sympathetic-dependent mechanisms, which can be partly attenuated with habitual aerobic exercise. Rapid vasodilation involves noradrenergic neurotransmitters in young trained men, and non-adrenergic sympathetic cotransmitters (e.g., neuropeptide Y) in young sedentary and older trained men, possibly as a compensatory mechanism. Finally, in older sedentary men, the rapid vasodilation appears not to involve the sympathetic system

Economics of direct seeding and planting for establishing oak stands on old-field sites in the South.

On old-field sites in the South, oak stand may be established by direct seeding of acorns, or by planting seed- lings. Planting seedlings costs approximately 21/2 times the cost of direct seeding on a per acre basis, and based on our study of overall costs and returns, we conclude that in most cases the additional costs of planting are not justified by the additional benefits. Direct seeding is therefore an eco- nomically viable alternative to planting, although success with seeding requires careful selection of species/site combinations and proper seed handling and storag

Species Richness, Distribution, and Relative Abundance of Freshwater Mussels (Bivalvia: Unionidae) of the Buffalo National River, Arkansas

The Buffalo River in north-central Arkansas is approximately 246 km long and flows through the Boston Mountains and Springfield and Salem Plateaus to the White River near Buffalo City. The Buffalo River is America’s first National River with the National Park Service owning 11% of land in the watershed. The objectives of this project were to survey the entire perennially wet length of river, search for mussels of conservation concern, and document the freshwater mussel assemblages. During 2004 and 2005, 235 km of the river were qualitatively and quantitatively surveyed. We documented 64 mussel assemblages. Time constrained qualitatively sampled assemblages (n=41) resulted in a mean richness of 7.8 with a range of 2 to 12 species. Quantitatively sampled mussel assemblages (n=23) had a mean richness of 9.5, ranging from 4 to 16 species and a mean density of 6.9 individuals/m2 , ranging from 1.3 to 25.6 individuals/m2 . Detrended correspondence analysis revealed 4 distinct community types dominated by: 1) Ptychobranchus occidentalis (Conrad 1836), 2) Villosa iris (Lea 1829), 3) Cyclonaias tuberculata (Rafinesque 1820), and 4) Actinonaias ligamentina (Lamarck 1819) that represented approximate species gradients along the river’s length. Previous surveys collectively recorded a total of 26 species for the river, however; only 23 species were identified in this survey with no federally listed threatened or endangered species found. The Buffalo National River has a moderately diverse and abundant native freshwater mussel fauna. Seventy-eight percent of the current species are considered to be of conservation concern (S1-S3). Consequently, the Buffalo National River may prove to be an important refuge for a declining mussel resource

Loss of high-level perceptual knowledge of object structure in DAT

Peer reviewe

Laplacian-level density functionals for the kinetic energy density and exchange-correlation energy

We construct a Laplacian-level meta-generalized gradient approximation (meta-GGA) for the non-interacting (Kohn-Sham orbital) positive kinetic energy density $\tau$ of an electronic ground state of density $n$. This meta-GGA is designed to recover the fourth-order gradient expansion $\tau^{GE4}$ in the appropiate slowly-varying limit and the von Weizs\"{a}cker expression $\tau^{W}=|\nabla n|^2/(8n)$ in the rapidly-varying limit. It is constrained to satisfy the rigorous lower bound $\tau^{W}(\mathbf{r})\leq\tau(\mathbf{r})$. Our meta-GGA is typically a strong improvement over the gradient expansion of $\tau$ for atoms, spherical jellium clusters, jellium surfaces, the Airy gas, Hooke's atom, one-electron Gaussian density, quasi-two dimensional electron gas, and nonuniformly-scaled hydrogen atom. We also construct a Laplacian-level meta-GGA for exchange and correlation by employing our approximate $\tau$ in the Tao, Perdew, Staroverov and Scuseria (TPSS) meta-GGA density functional. The Laplacian-level TPSS gives almost the same exchange-correlation enhancement factors and energies as the full TPSS, suggesting that $\tau$ and $\nabla^2 n$ carry about the same information beyond that carried by $n$ and $\nabla n$. Our kinetic energy density integrates to an orbital-free kinetic energy functional that is about as accurate as the fourth-order gradient expansion for many real densities (with noticeable improvement in molecular atomization energies), but considerably more accurate for rapidly-varying ones.Comment: 9 pages, 16 figure

Tropical cyclone projections: changing climate threats for Pacific island defense installations

Potential changing climate threats in the tropical and subtropical North Pacific Ocean were assessed, using coupled ocean-atmosphere and atmosphere-only general circulation models, to explore their response to projected increasing greenhouse gas emissions. Tropical cyclone occurrence, described by frequency and intensity, near islands housing major U.S. defense installations was the primary focus. Four island regions-Guam and Kwajalein Atoll in the tropical northwestern Pacific, Okinawa in the subtropical northwestern Pacific, and Oahu in the tropical north-central Pacific-were considered, as they provide unique climate and geographical characteristics that either enhance or reduce the tropical cyclone risk. Guam experiences the most frequent and severe tropical cyclones, which often originate as weak systems close to the equator near Kwajalein and sometimes track far enough north to affect Okinawa, whereas intense storms are the least frequent around Oahu. From assessments of models that simulate well the tropical Pacific climate, it was determined that, with a projected warming climate, the number of tropical cyclones is likely to decrease for Guam and Kwajalein but remain about the same near Okinawa and Oahu; however, the maximum intensity of the strongest storms may increase in most regions. The likelihood of fewer but stronger storms will necessitate new localized assessments of the risk and vulnerabilities to tropical cyclones in the North Pacific

Book Reviews

Reviews of the following books: Mainers in the Civil War by Harry Gratwick; The 22nd Maine Volunteer Infantry in the Civil War: A History and Roster by Ned Smith; Write Quick: War and a Woman\u27s Life in Letters 1835-1867 Edited by Ann Fox Chandonnet and Robert Gibson Pevear; Civil War Senator: William Pitt Fessenden and the Fight to Save the American Republic by Robert J. Cook; Lincoln\u27s Friend: Leonard Swett by Robert S. Eckley; We Are in His Hands Whether We Live or Die: The Letters of Brevet Brigadier General Charles Henry Howard edited by David K. Thomson; Fanny & Joshua: The Enigmatic Lives of Frances Caroline Adams and Joshua Lawrence Chamberlain by Diane Monroe Smith; This Birth Place of Souls:The Civil War Nursing Diary of Harriet Eaton edited with an Introduction by Jane E. Schultz; Army at Home: Women and the Civil War on the Northern Home Front by Judith Giesberg; A Visitation of God: Northern Civilians Interpret the Civil War by Sean A. Scott; Freedom National: The Destruction of Slavery in the United States, 1861-1865 by James Oakes; War Upon the Land: Military Strategy and the Transformation of Southern Landscapes during the American Civil War by Lisa M. Brady; Remembering the Civil War: Reunion and the Limits of Reconciliation by Caroline E. Janne