University of Nevada, Reno

About: University of Nevada, Reno is a education organization based out in Reno, Nevada, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 13561 authors who have published 28217 publications receiving 882002 citations. The organization is also known as: University of Nevada & Nevada State University.

A theory-driven approach to tree-ring standardization: defining the biological trend from expected basal area increment

Abstract: One of the main elements of dendrochronological standardization is removing the biological trend, i.e. the progressive decline of ring width along a cross-sectional radius that is caused by the corresponding increase in stem size and tree age over time. The ‘‘conservative’’ option for removing this biological trend is to fit a modified negative exponential curve (or a straight line with slope # 0) to the ring-width measurements. This method is based on the assumption that, especially for open-grown and/or shade-intolerant species, annual growth rate of mature trees fluctuates around a specific level, expressed by a constant ring width. Because this method has numerical and conceptual drawbacks, we propose an alternative approach based on the assumption that constant growth is expressed by a constant basal area increment distributed over a growing surface. From this starting point, we derive a mathematical expression for the biological trend of ring width, which can be easily calculated and used for dendrochronological standardization. The proposed C-method is compared to other standardization techniques, including Regional Curve Standardization (RCS), of tree-ring width from ponderosa pines (Pinus ponderosa Douglas ex P.Lawson & C.Lawson) located at the Gus Pearson Natural Area (GPNA) in northern Arizona, USA. Master ring-index chronologies built from ring area, RCS, and C-method reproduced stand-wide patterns of tree growth at the GPNA, whereas other standardization options, including the ‘‘conservative’’ one, failed to do so. In addition, the C-method has the advantage of calculating an expected growth curve for each tree, whereas RCS is based on applying the same growth curve to all trees. In conclusion, the C-method replaces the purely empirical ‘‘conservative’’ option with a theorybased approach, which is applicable to individual ring-width measurement series, does not require fitting a growth curve using nonlinear regression, and can be rigorously tested for improving tree-ring records of environmental changes.

Thermal pretreatment of lignocellulosic biomass

Abstract: Torrefaction is a process to convert diverse lignocellulosic biomass feedstocks into an energy dense homogeneous solid, a pretreatment for subsequent thermochemical conversion. Loblolly pine was treated by wet torrefaction (hot compressed water, 200–260°C) and dry torrefaction (nitrogen, 250–300°C), with mass yield of solid product ranging between 57 and 89%, and energy densification to 108–136% of the original feedstock. The solid product has been characterized, including proximate analysis, fiber analysis, ultimate analysis, and equilibrium moisture. In both dry and wet torrefaction, increasing temperature results in decreased mass yield and increased energy densification, and results in a solid with increased carbon content, decreased oxygen content, and decreased volatiles. The biomass is transformed into a fuel similar to a low-rank coal. Generally, the wet torrefaction process produces a solid with greater energy density than dry torrefaction, with the same mass yield. The fiber analysis indicates that hemicellulose is quickly removed during wet torrefaction, and the solid product contains substantial quantities of aqueous soluble compounds. The equilibrium moisture content of solids produced by both processes is somewhat decreased from that of the biomass feedstock, indicating a hydrophobic solid suitable for storage and transportation. © 2009 American Institute of Chemical Engineers Environ Prog, 2009

Interstitial Cells of Cajal Mediate Cholinergic Neurotransmission from Enteric Motor Neurons

Abstract: Interstitial cells of Cajal (ICC) are interposed between enteric neurons and smooth muscle cells in gastrointestinal muscles The role of intramuscular ICC (IC-IM) in mediating enteric excitatory neural inputs was studied using gastric fundus muscles of wild-type animals and W/Wv mutant mice, which lack IC-IM Excitatory motor neurons, labeled with antibodies to vesicular acetylcholine transporter or substance-P, were closely associated with IC-IM Immunocytochemistry showed close contacts between enteric neurons and IC-IM IC-IM also formed gap junctions with smooth muscle cells Electrical field stimulation yielded fast excitatory junction potentials in the smooth muscle that were blocked by atropine Neural responses were greatly reduced in muscles ofW/Wv animals Loss of cholinergic responses in W/Wv muscles seemed to be caused by the loss of close synaptic contacts between motor neurons and IC-IM, because these muscles were not less responsive to exogenous acetylcholine than were wild-type musclesW/Wv muscles also responded to excitatory nerve stimulation when the breakdown of acetylcholine was blocked by neostigmine The density of cholinergic nerve bundles within the muscles was not significantly different in wild-type andW/Wv muscles, and similar amounts of14[C]choline were released from preloaded wild-type andW/Wv muscles in response to nerve stimulation The impact of losing IC-IM on gastric compliance was also evaluated in intact stomachs Pressure increased as a function of fluid volume and infusion rate in wild-type animals, butW/Wv animals showed little basal tone and minimal increases in pressure with fluid infusions These data suggest that IC-IM play a major role in receiving cholinergic excitatory inputs from the enteric nervous system in the murine fundus

Linking Management Behavior to Ethical Philosophy—An Empirical Investigation

Abstract: Ethical theory is linked to management behavior by classifying responses of managers to a series of vignettes according to the ethical theory represented by the response. The vignettes represent ethical dilemmas in the following areas: (I) coercion and control, (2) conflict of interest, (3) physical environment, (4) paternalism, and (5) personal integrity.