4,579 research outputs found
Effect of woodstack structure on invertebrate abundance and diversity
Reduced quantities of dead wood in managed forests have resulted in a reduction in the abundance and diversity of saproxylic invertebrates to the extent that many are now considered red list species. To mitigate against this loss, one conservation measure is the provision of dead wood, in the form of piles of chopped logs, i.e. âwoodstacksâ. The heterogeneity and volume of dead wood habitat is considered to be an important component of habitat suitability. However, the value of different woodstack types to invertebrate conservation has rarely been quantified and there is little consensus on how to best to survey the invertebrate fauna of woodstacks. This study used both sticky traps and pitfall traps to sample the invertebrate fauna of three types of sycamore woodstack. Woodstacks were made from 10 logs, 20 logs and 10 scorched logs plus a control woodstack made of unplasticised polyvinyl chloride (uPVC) plastic piping and observed over a 4-week period. A total of 1446 invertebrates from 16 orders, including 127 Coleoptera, were caught during the sampling period. A generalized linear model was used to analyse invertebrate abundance between woodstack and between trap types, and diversity was determined using Shannon diversity indices and analysed using a two-way Analysis of Variance (ANOVA). The woodstack type had no effect on the abundance of invertebrates. However, Shannon diversity was highest on the scorched woodstacks, with little difference between the 10 and 20â
log stacks and the control uPVC woodstacks. However, closer inspection of orders revealed the uPVC woodstacks to have the lowest abundance and diversity of Coleoptera. This study suggests that constructing woodstacks can provide suitable habitat for a variety of invertebrates. However, these invertebrates may have simply used the structures for shelter and the true value with saproxylic invertebrates could not be measured in this 4-week study. To fully appreciate the conservation value of woodstacks will require longer term studies that examine how and when saproxylic invertebrates use dead and decaying wood
Additive decompositions for rings of modular forms
We study rings of integral modular forms for congruence subgroups as modules
over the ring of integral modular forms for the full modular group. In many
cases these modules are free or decompose at least into well-understood pieces.
We apply this to characterize which rings of modular forms are Cohen--Macaulay
and to prove finite generation results. These theorems are based on
decomposition results about vector bundles on the compactified moduli stack of
elliptic curves.Comment: Complete revision. Comments welcome. arXiv admin note: text overlap
with arXiv:1609.0926
Chemical effects in ion mixing of a ternary system (metal-SiO_2)
The mixing of Ti, Cr, and Ni thin films with SiO_2 by lowâtemperature (â196â25â°C) irradiation with 290 keV Xe has been investigated. Comparison of the morphology of the intermixed region and the dose dependences of net metal transport into SiO_2 reveals that long range motion and phase formation probably occur as separate and sequential processes. Kinetic limitations suppress chemical effects in these systems during the initial transport process. Chemical interactions influence the subsequent phase formation
The Intensity Profile of the Solar Supergranulation
We have measured the average radial (cell center to network boundary) profile
of the continuum intensity contrast associated with supergranular flows using
data from the Precision Solar Photometric Telescope (PSPT) at the Mauna Loa
Solar Observatory (MLSO). After removing the contribution of the network flux
elements by the application of masks based on Ca II K intensity and averaging
over more than 10^5 supergranular cells, we find a ~ 0.1% decrease in red and
blue continuum intensity from the supergranular cell centers outward,
corresponding to a ~ 1.0 K decrease in brightness temperature across the cells.
The radial intensity profile may be caused either by the thermal signal
associated with the supergranular flows or a variation in the packing density
of unresolved magnetic flux elements. These are not unambiguously distinguished
by the observations, and we raise the possibility that the network magnetic
fields play an active role in supergranular scale selection by enhancing the
radiative cooling of the deep photosphere at the cell boundaries.Comment: Accepted to Ap
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Hostile behavior as a function of strength of need, degree of insight, and need-relevance of the stimulus.
Near-Earth Ion Irradiation Effects on Functional Ceramic Materials: A Combined Experimental-Monte Carlo Approach
The near-Earth space radiation environment is a complex system that creates a harmful environment for materials to operate in. Motivated by the search for using optical defects as an indicator of radiation damage, five single-crystal functional ceramic materials were selected to undergo ion irradiation at conditions found in the near-Earth space environment. Due to the complex nature of ion irradiation effects in ceramic materials, a host of calculations and experimental characterization methods were used. Calculations using the 2013 SRIM code were used to evaluate the ion projected range and the type and number of defects (vacancies) created by ion irradiation. Structural characterization by Raman spectroscopy was combined with results from UV-visible spectroscopy, radioluminescence, and thermoluminescence to determine changes induced by ion irradiation. This work revealed that the structure and optical properties are sensitive to ion irradiation and can be experimentally characterized by the methods used
A Framework for the Economic Analysis of Ditch System Management Alternatives
Replaced with revised version of paper 05/10/06.Land Economics/Use,
Methods for identifying surgical wound infection after discharge from hospital: a systematic review.
Background: Wound infections are a common complication of surgery that add significantly to the morbidity of patients and costs of treatment. The global trend towards reducing length of hospital stay post-surgery and the increase in day case surgery means that surgical site infections (SSI) will increasingly occur after hospital discharge. Surveillance of SSIs is important because rates of SSI are viewed as a measure of hospital performance, however accurate detection of SSIs post-hospital discharge is not straightforward. Methods: We conducted a systematic review of methods of post discharge surveillance for surgical wound infection and undertook a national audit of methods of post-discharge surveillance for surgical site infection currently used within United Kingdom NHS Trusts. Results: Seven reports of six comparative studies which examined the validity of post-discharge surveillance methods were located; these involved different comparisons and some had methodological limitations, making it difficult to identify an optimal method. Several studies evaluated automated screening of electronic records and found this to be a useful strategy for the identification of SSIs that occurred post discharge. The audit identified a wide range of relevant post-discharge surveillance programmes in England, Scotland and Wales and Northern Ireland; however, these programmes used varying approaches for which there is little supporting evidence of validity and/or reliability. Conclusion: In order to establish robust methods of surveillance for those surgical site infections that occur post discharge, there is a need to develop a method of case ascertainment that is valid and reliable post discharge. Existing research has not identified a valid and reliable method. A standardised definition of wound infection ( e. g. that of the Centres for Disease Control) should be used as a basis for developing a feasible, valid and reliable approach to defining post discharge SSI. At a local level, the method used to ascertain post discharge SSI will depend upon the purpose of the surveillance, the nature of available routine data and the resources available
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