Effects of post-fire logging on forest surface air temperatures in the Siskiyou Mountains, Oregon, USA

Following stand-replacing wildfire, post-fire (salvage) logging of fire-killed trees is a widely implemented management practice in many forest types. A common hypothesis is that removal of fire-killed trees increases surface temperatures due to loss of shade and increased solar radiation, thereby influencing vegetation establishment and possibly stand development. Six years after a wildfire in a Mediterranean-climate mixed-conifer forest in southwest Oregon, USA, we measured the effects of post-fire logging (> 90 per cent dead tree (snag) removal) on growing season surface air temperatures. Compared with unlogged severely burned forest, post-fire logging did not lead to increased maximum daily surface air temperature. However, dead tree removal was associated with lower nightly minimum temperatures (similar to 1 degrees C) and earlier daytime heating, leading to a 1-2 degrees C difference during the warming portion of the day. Effects varied predictably by aspect. The patterns reported here represent a similar but muted pattern as previously reported for microclimatic changes following clear-cutting of green trees. Effects of microsites such as tree bases on fine-scale temperature regimes require further investigation

The intercept of the BFKL pomeron from Forward Jets at HERA

Recently the H1 and ZEUS collaborations have presented cross sections for DIS events with a forward jet. The BFKL formalism is able to produce an excellent fit to these data. The extracted intercept of the hard pomeron suggests that when all higher order corrections are taken into account the cross section will still rise very rapidly as expected for low $x$ dynamics.Comment: 10 pages, one figure, accepted for publication in PL

Forecasting Sovereign Default risk with Merton’s Model

Merton's structural model for sovereigns is proven to be useful to analyze the default risk of a country. We are the first to investigate how fast CDS spreads react to changes in model inputs and outputs. CDS spread changes strongly correlate with exchange rate returns, which are an input to the model. But CDS spread changes on average react with a delay to changes in model outputs such as the distance to default, the default probability and model spreads. Hence contingency claim analysis for sovereigns provides useful predictions for CDS spreads

The intermediate pyrolysis of de-inking sludge to produce a sustainable liquid fuel

De-inking sludge is a waste product generated from secondary fibre paper mills who manufacture recycled paper into new paper sheets; it refers directly to the solid residues which evolve during the de-inking stage of the paper pulping process. The current practice for the disposal of this waste is either by land-spreading, land-filling or incineration which are unsustainable. This work has explored the intermediate pyrolysis of pre-conditioned de-inking sludge pellets in a recently patented 20 kg/h intermediate pyrolysis reactor (The Pyroformer). The reactor is essentially two co-axial screws which are configured in such a way as to circulate solids within the reactor and thus facilitate in the cracking of tars. The potential application of using the volatile organic vapours and permanent gases evolved would be to generate both combined heat and power (CHP) located at paper making sites. The results show that de-inking sludge could be successfully pyrolysed and the organic vapours produced were composed of a mixture of aromatic hydrocarbons, phenolic compounds and some fatty acid methyl esters as detected by liquid GC-MS. The calorific value of the oil after condensing was between 36 and 37 MJ/kg and the liquid fuel properties were also determined, permanent gases were detected by a GC-TCD and were composed of approximately 24% CO, 6% CH and 70% CO (v/v%). The solid residue from pyrolysis also contained a small residual calorific value, and was largely composed of mainly calcium based inert metal oxides. The application of applying intermediate pyrolysis to de-inking sludge for both CHP production and waste reduction is in principle a feasible technology which could be applied at secondary fibre paper mills

Low-diffusivity scalar transport using a WENO scheme and dual meshing

Interfacial mass transfer of low-diffusive substances in an unsteady flow environment is marked by a very thin boundary layer at the interface and other regions with steep concentration gradients. A numerical scheme capable of resolving accurately most details of this process is presented. In this scheme, the fourth-order accurate WENO method developed by Liu et al. (1994) was implemented on a non-uniform staggered mesh to discretize the scalar convection while for the scalar diffusion a fourth-order accurate central discretization was employed. The discretization of the scalar convection-diffusion equation was combined with a fourth-order Navier-Stokes solver which solves the incompressible flow. A dual meshing strategy was employed, in which the scalar was solved on a finer mesh than the incompressible flow. The solver was tested by performing a number of two-dimensional simulations of an unstably stratified flow with low diffusivity scalar transport. The unstable stratification led to buoyant convection which was modelled using a Boussinesq approximation with a linear relationship between flow temperature and density. The order of accuracy for one-dimensional scalar transport on a stretched and uniform grid was also tested. The results show that for the method presented above a relatively coarse mesh is sufficient to accurately describe the fluid flow, while the use of a refined mesh for the low-diffusive scalars is found to be beneficial in order to obtain a highly accurate resolution with negligible numerical diffusion

A Completely Endovascular Solution for Transcatheter Aortic Valve Implantation Embolisation and Inversion into the Aortic Arch

Introduction: Transcatheter aortic valve implantation (TAVI) has evolved into the preferred alternative to surgical valve replacement for severe aortic valve stenosis with high surgical risk. With expanding indications, life threatening complications including transcatheter aortic valve embolisation and inversion (TAVEI), in which the valve dislodges, inverts, and migrates caudally, may increase concomitantly. Report: An 80 year old male with severe aortic valve stenosis underwent balloon expandable transcatheter aortic valve implantation (TAVI). Valve embolisation into the aortic arch inverted the bioprothesis, excluding the option of fixation in the descending aorta. Through-valve thoracic endovascular aortic repair (TEVAR) was performed after bifemoral snaring using a through-and-through wire technique and pulling the valve into the descending aorta. Discussion: TAVI is emerging as the preferred treatment for severe aortic valve stenosis and comes with unique procedural complications, such as life threatening transcatheter aortic valve embolisation and inversion (TAVEI). Although some authors prefer treating embolisation of a non-inverted balloon expandable valve into the aorta by using the valvuloplasty balloon to pull the valve distally and fixing it in the descending aorta, this risks further expansion of the valve and consequently fixing it in an undesirable position and is not possible if the valve inverts. Downstream placement of the valve by snaring with a guiding catheter covering/protecting a through-and-through wire technique, combined with through-valve TEVAR, provides a new bail out strategy for this serious complication and may reduce TAVEI associated mortality and morbidity

Effects of minor compounds from virgin olive oil on inflammatory response in human leukocytes

Mediterranean diet protects against cardiovascular diseases such as atherosclerosis, now considered an inflammatory disorder. Virgin olive oil is one of the most important foods in this diet, leading to the suggestion that health benefits of Mediterranean diet are achieved at least partially due to the consumption of virgin olive oil. Extra virgin olive oil (EVOO) is the highest quality oil based on its chemical and sensorial properties. Our aim was to evaluate the anti-inflammatory effects of minor compounds found in the unsaponifibale fraction of EVOO on activated human monocytes and neutrophils. For this purpose, we isolated monocytes and neutrophils from blood samples of healthy volunteers. We also isolated the unsaponifiable fraction (UF) from EVOO. Cells were incubated with UF at different concentrations and the pro-inflammatory stimulus LPS. Afterwards, RNA was obtained from cells and then converted into cDNA. The relative gene expression of pro-inflammatory and anti-inflammatory markers was assessed by qRT-PCR. We found that UF from EVOO reduced relative gene expression of pro-inflammatory markers in a dose-dependent manner both in human monocytes and neutrophils. In contrast, UF from EVOO increased relative gene expression of anti-inflammatory markers in these cells. These findings unveil a role of UF from EVOO in the benefits from consumption of EVOO in disorders related to inflammation

Inclusive particle production at HERA: Higher-order QCD corrections to the resolved quasi-real photon contribution

We calculate in next-to-leading order inclusive cross sections of single-particle production via resolved photons in $ep$ collisions at HERA. Transverse-momentum and rapidity distributions are presented and the scale dependence is studied. The results are compared with first experimental data from the H1 Collaboration at HERA.Comment: 11 pages with 15 uuencoded PS figures. Preprint DESY 93-03