Variability in Forest Floor Mass and Nutrient Concentration of Mature Pine-Hardwoods in the Ouachita Mountains

Prior to timber harvesting, forest floor mass and nutrient concentrations in forest floor and mineral soil were determined in 24 mature, shortleaf pine (Pinus echinata Mill.)-hardwood stands occurring within the northern, eastern, southern and western sub-ecoregions of the Ouachita Mountains. The forest floor samples were collected at each of three locations representing the lower, mid, and upper slope positions within each stand. Samples of the L-(litter) and F-layers (fermentation) were collected separately. Materials from the L-layer were differentiated into hardwood foliage, pine foliage, and woody/reproductive components. Mass and nutrient concentrations of the various forest floor components were compared among slope positions and among sub-ecoregions to evaluate the influence of these factors on forest floor pools. Forest floor mass and nutrient concentrations generally did not differ among slope positions. Although mass did not differ among sub-ecoregions, forest floor concentrations of Ca, Mg, and Mn were significantly higher in the northern than the eastern or southern portion of the Ouachita Mountains

HYDROLOGIC EVALUATION OF RESIDENTIAL RAIN GARDENS USING A STORMWATER RUNOFF SIMULATOR

Engineered bioretention cells with underdrains have shown water quality and hydrologic benefits for abating urban stormwater problems. Less is known about the hydrologic performance of residential rain gardens that rely on in situ soil infiltration as the primary mechanism of volume control. Eleven residential rain gardens in Lincoln, Nebraska, were evaluated using a variable-rate stormwater runoff simulator. A volume-based water quality volume (WQV) design storm of 3.0 cm was applied to each rain garden as an SCS Type II runoff hydrograph until the system began overflowing to test the rain gardens for surface and subsurface storage capacity, drawdown rate, ponding depth, and overflow characteristics. Every rain garden tested drained in 30 h or less, with six gardens draining in less than 1 h. Rain garden surface storage capacity was poor, retaining on average only 16% of the WQV. On average, the rain gardens studied could store and infiltrate only 40% of the WQV, with only two gardens able to store and infiltrate greater than 90% of the WQV. On average, 59% of the runoff was captured as subsurface storage. Results of this study indicate that these 2- to 4-year-old rain gardens are limited not by drain times and rates, which often met or exceeded common design recommendations, but rather by inadequate surface storage characteristics. Extrapolating measured surface storage volumes to hypothetical systems with evenly graded depths of 15.2 cm, a minimum local depth recommendation, resulted in only one garden with enough storage to contain the WQV. On average, the extrapolated storage held only 65% of the WQV. It was shown that subsurface storage can make up for a lack of surface storage; the systems studied herein had an average of 2.7 times more subsurface storage than surface storage as a percentage of inflow volume before overflow began

Selection Factors in Housing Among Rural Low-To-Moderate Income Residents

Growth in rural areas has increased the need to examine more closely the quality and acceptability of different types of existing housing. This study focuses on the reasons rural residents moved to their housing and whether their needs were satisfied by their selections. Comparisons of reasons for moving among conventional home, mobile home, and apartment residents indicated similar motivations for housing choices. Comparisons of present housing satisfaction revealed that a large majority of all respondents selected housing that met their needs. The results suggest that despite the predominant preference for single-family conventionally built homes, a substantial portion of future housing demand for low-to-moderately priced housing in rural areas could be accommodated quite adequately with nonconventional housing such as mobile homes and apartments

An Effective Theory for Midgap States in Doped Spin Ladder and Spin-Peierls Systems: Liouville Quantum Mechanics

In gapped spin ladder and spin-Peierls systems the introduction of disorder, for example by doping, leads to the appearance of low energy midgap states. The fact that these strongly correlated systems can be mapped onto one dimensional noninteracting fermions provides a rare opportunity to explore systems which have both strong interactions and disorder. In this paper we show that the statistics of the zero energy midgap wave functions in these models can be effectively described by Liouville Quantum Mechanics. This enables us to calculate the disorder averaged N-point correlation functions of these states (the explicit calculation is performed for N=2,3). We find that whilst these midgap states are typically weakly correlated, their disorder averaged correlation are power law. This discrepancy arises because the correlations are not self-averaging and averages of the wave functions are dominated by anomalously strongly correlated configurations.Comment: 13 page latex fil

System for the measurement of ultra-low stray light levels

An apparatus is described for measuring the effectiveness of stray light suppression light shields and baffle arrangements used in optical space experiments and large space telescopes. The light shield and baffle arrangement and a telescope model are contained in a vacuum chamber. A source of short, high-powered light energy illuminates portions of the light shield and baffle arrangement and reflects a portion of same to a photomultiplier tube by virtue of multipath scattering. The resulting signal is transferred to time-channel electronics timed by the firing of the high energy light source allowing time discrimination of the signal thereby enabling the light scattered and suppressed by the model to be distinguished from the walls and holders around the apparatus

Dental Pulp Cell Behavior in Biomimetic Environments

There is emerging recognition of the importance of a physiologically relevant in vitro cell culture environment to promote maintenance of stem cells for tissue engineering and regenerative medicine purposes. In vivo, appropriate cellular cues are provided by local tissue extracellular matrix (ECM), and these are not currently recapitulated well in vitro using traditional cultureware. We therefore hypothesized that better replication of the in vivo environment for cell culture and differentiation could be achieved by culturing dental pulp cells with their associated ECM. Primary dental pulp cells were subsequently seeded onto pulp-derived ECM-coated cultureware. While at up to 24 h they exhibited the same level of adherence as those cells seeded on tissue culture–treated surfaces, by 4 d cell numbers and proliferation rates were significantly decreased in cells grown on pulp ECM compared with controls. Analysis of stem cell and differentiation marker transcripts, as well as Oct 3/4 protein distribution, supported the hypothesis that cells cultured on ECM better maintained a stem cell phenotype compared with those cultured on standard tissue culture–treated surfaces. Subsequent differentiation analysis of cells cultured on ECM demonstrated that they exhibited enhanced mineralization, as determined by alizarin red staining and mineralized marker expression. Supplementation of a 3% alginate hydrogel with pulp ECM components and dental pulp cells followed by differentiation induction in mineralization medium resulted in a time-dependent mineral deposition at the periphery of the construct, as demonstrated histologically and using micro–computed tomography analysis, which was reminiscent of tooth structure. In conclusion, data indicate that culture of pulp cells in the presence of ECM better replicates the in vivo environment, maintaining a stem cell phenotype suitable for downstream tissue engineering applications

Lower Neutrino Mass Bound from SN1987A Data and Quantum Geometry

A lower bound on the light neutrino mass $m_\nu$ is derived in the framework of a geometrical interpretation of quantum mechanics. Using this model and the time of flight delay data for neutrinos coming from SN1987A, we find that the neutrino masses are bounded from below by $m_\nu\gtrsim 10^{-4}-10^{-3}$eV, in agreement with the upper bound $m_\nu\lesssim$ $({\cal O}(0.1) - {\cal O} (1))$ eV currently available. When the model is applied to photons with effective mass, we obtain a lower limit on the electron density in intergalactic space that is compatible with recent baryon density measurements.Comment: 22 pages, 3 figure

An Inversion Disrupting FAM134B Is Associated with Sensory Neuropathy in the Border Collie Dog Breed

Sensory neuropathy in the Border Collie is a severe neurological disorder caused by the degeneration of sensory and, to a lesser extent, motor nerve cells with clinical signs starting between 2 and 7 months of age. Using a genome-wide association study approach with three cases and 170 breed matched controls, a suggestive locus for sensory neuropathy was identified that was followed up using a genome sequencing approach. An inversion disrupting the candidate gene FAM134B was identified. Genotyping of additional cases and controls and RNAseq analysis provided strong evidence that the inversion is causal. Evidence of cryptic splicing resulting in novel exon transcription for FAM134B was identified by RNAseq experiments. This investigation demonstrates the identification of a novel sensory neuropathy associated mutation, by mapping using a minimal set of cases and subsequent genome sequencing. Through mutation screening, it should be possible to reduce the frequency of or completely eliminate this debilitating condition from the Border Collie breed population

Image Analysis of Primary Bone-Derived Cells on Different Polystyrene Surfaces

The aim of the present study was to examine whether two different cell populations could be discerned using image analysis of a variety of morphological parameters on bacteriological and tissue culture polystyrene surfaces. Rat periosteal and osteoblast cultures were established on both polystyrene petri dishes and examined using phase contrast microscopy after one and two weeks before capturing digital images which were stored on a personal computer. The digital images were processed to identify the cell margins or perimeter, from which seven different morphological parameters were calculated using a program developed (by GL) for both the cell populations on the two polystyrene surfaces. None of the morphological parameters were able to distinguish between all of the culture types, so discriminant analyses were applied using different combinations of the parameters. The best discrimination between the different cell outlines was found after one week using 5 of the parameters combined in a quadratic discriminant analysis, which allocated 94% of the outlines to their correct group and 94% after two weeks using all the parameters. The study demonstrated that it was possible to quantify morphological differences between two cell populations grown on either tissue culture or bacteriological polystyrene petri dishes. It may be possible to develop this image and statistical analysis further to allow non-invasive automatic identification of particular cells in mixed populations in vitro