The effects of stand thinning on soil erosion rates at Jim's Creek in the Willamette National Forest, Oregon

Surface sediment transport is an important geomorphic process which can be significantly altered by management activities in forested ecosystems. Disturbance of the soil surface may result in increased sediment delivery to fish bearing streams and degradation of soil structure. Selective thinning and low impact yarding techniques were utilized in an effort to restore oak savanna ecosystem structure to the Jim’s Creek Savanna Restoration Project Area southeast of Oakridge, Oregon. This study monitored sediment transport rates following the thinning of nearly 90% of the existing 120 year old Douglas-fir stand within the project boundary. The study followed a before-after control-impact (BACI) design, in which the 12 sediment traps were monitored for 12 months prior to thinning, were removed during the logging activities, and then returned to the same locations following the thinning and monitored for an additional 2 year period. Estimated soil erosion rates derived from traps were then compared to baseline (pre-restoration) transport rates collected at the same locations in a previous study to assess change over time. Two control traps were included in the analysis and were placed in an area that did not undergo thinning activities during the study. The rest of the traps were place in areas in which thinning via skyline yarding techniques occurred (near the existing road network) or in areas where helicopter yarding was utilized to remove felled trees. Average estimated soil erosion rates from traps located in thinned areas declined from 983.5 g/m/yr to 379.8 g/m/yr following logging activities at the site; and rates declined from 156.5 to 84.1 at the two untreated reference plots. Previous work at the site suggests that rain- and throughfall-drop splash is the dominant surface soil erosion mechanism and that an alteration of canopy structure may influence this process. Reduced canopy structure can lead to a reduction in throughfall splash erosion. The hypothetical reduction in throughfall splash combined with possible loss of drop splash by fog drip as a result of canopy thinning may explain the observed decrease in surface soil erosion following stand thinning. There is some indication of a difference in the seasonality of peak surface sediment transport following the site treatments. However, this comparison may not be valid due to the duration of the pre-treatment study not including the later summer months which were included in the post-treatment monitoring and consistently showed the highest transport rates. Surface soil transport was simulated using a non-linear diffusion model as well as a version of the web-based GIS WEPP erosion model. Simulated rates generally poorly represented observed rates, and the WEPP model consistently over-predicted surface sediment transport rates. Continuation of existing erosion boxes and addition of sites to sample a range of canopy cover conditions would increase understanding of effects of canopy influences and long-term effects of site disturbance. Acquiring a finer scale digital elevation model may facilitate more accurate modeling of surface erosion

CIB1 is an endogenous inhibitor of agonist-induced integrin αIIbβ3 activation

In response to agonist stimulation, the αIIbβ3 integrin on platelets is converted to an active conformation that binds fibrinogen and mediates platelet aggregation. This process contributes to both normal hemostasis and thrombosis. Activation of αIIbβ3 is believed to occur in part via engagement of the β3 cytoplasmic tail with talin; however, the role of the αIIb tail and its potential binding partners in regulating αIIbβ3 activation is less clear. We report that calcium and integrin binding protein 1 (CIB1), which interacts directly with the αIIb tail, is an endogenous inhibitor of αIIbβ3 activation; overexpression of CIB1 in megakaryocytes blocks agonist-induced αIIbβ3 activation, whereas reduction of endogenous CIB1 via RNA interference enhances activation. CIB1 appears to inhibit integrin activation by competing with talin for binding to αIIbβ3, thus providing a model for tightly controlled regulation of αIIbβ3 activation

Scale-invariance in expanding and contracting universes from two-field models

We study cosmological perturbations produced by the most general two-derivative actions involving two scalar fields, coupled to Einstein gravity, with an arbitrary field space metric, that admit scaling solutions. For contracting universes, we show that scale-invariant adiabatic perturbations can be produced continuously as modes leave the horizon for any equation of state parameter $w \ge 0$. The corresponding background solutions are unstable, which we argue is a universal feature of contracting models that yield scale-invariant spectra. For expanding universes, we find that nearly scale-invariant adiabatic perturbation spectra can only be produced for $w \approx -1$, and that the corresponding scaling solutions are attractors. The presence of a nontrivial metric on field space is a crucial ingredient in our results.Comment: 23 pages, oversight in perturbations calculation corrected, conclusions for expanding models modifie

Revisiting consistency with random utility maximisation: theory and implications for practical work

While the paradigm of utility maximisation has formed the basis of the majority of applications in discrete choice modelling for over 40 years, its core assumptions have been questioned by work in both behavioural economics and mathematical psychology as well as more recently by developments in the RUM-oriented choice modelling community. This paper reviews the basic properties with a view to explaining the historical pre-eminence of utility maximisation and addresses the question of what departures from the paradigm may be necessary or wise in order to accommodate richer behavioural patterns. We find that many, though not all, of the behavioural traits discussed in the literature can be approximated sufficiently closely by a random utility framework, allowing analysts to retain the many advantages that such an approach possesses

Changes in white cell estimates and plasma chemistry measurements following oral or external dosing of double-crested cormorants, \u3ci\u3ePhalacocorax auritus\u3c/i\u3e, with artificially weathered MC252 oil

Scoping studies were designed whereby double-crested cormorants (Phalacocorax auritus) were dosed with artificially weathered Deepwater Horizon (DWH) oil either daily through oil injected feeder fish, or by application of oil directly to feathers every three days. Preening results in oil ingestion, and may be an effective means of orally dosing birds with toxicant to improve our understanding of the full range of physiological effects of oral oil ingestion on birds. Blood samples collected every 5–6 days were analyzed for a number of clinical endpoints including white blood cell (WBC) estimates and differential cell counts. Plasma biochemical evaluations were performed for changes associated with oil toxicity. Oral dosing and application of oil to feathers resulted in clinical signs and statistically significant changes in a number of biochemical endpoints consistent with petroleum exposure. In orally dosed birds there were statistically significant decreases in aspartate amino transferase (AST) and gamma glutamyl transferase (GGT) activities, calcium, chloride, cholesterol, glucose, and total protein concentrations, and increases in plasma urea, uric acid, and phosphorus concentrations. Plasma electrophoresis endpoints (pre-albumin, albumin, alpha-2 globulin, beta globulin, and gamma globulin concentrations and albumin: globulin ratios) were decreased in orally dosed birds. Birds with external oil had increases in urea, creatinine, uric acid, creatine kinase (CK), glutamate dehydrogenase (GLDH), phosphorus, calcium, chloride, potassium, albumin, alpha-1 globulin and alpha-2 globulin. Decreases were observed in AST, beta globulin and glucose. WBC also differed between treatments; however, this was in part driven by monocytosis present in the externally oiled birds prior to oil treatment

Changes in white cell estimates and plasma chemistry measurements following oral or external dosing of double-crested cormorants, \u3ci\u3ePhalacocorax auritus\u3c/i\u3e, with artificially weathered MC252 oil

Scoping studies were designed whereby double-crested cormorants (Phalacocorax auritus) were dosed with artificially weathered Deepwater Horizon (DWH) oil either daily through oil injected feeder fish, or by application of oil directly to feathers every three days. Preening results in oil ingestion, and may be an effective means of orally dosing birds with toxicant to improve our understanding of the full range of physiological effects of oral oil ingestion on birds. Blood samples collected every 5–6 days were analyzed for a number of clinical endpoints including white blood cell (WBC) estimates and differential cell counts. Plasma biochemical evaluations were performed for changes associated with oil toxicity. Oral dosing and application of oil to feathers resulted in clinical signs and statistically significant changes in a number of biochemical endpoints consistent with petroleum exposure. In orally dosed birds there were statistically significant decreases in aspartate amino transferase (AST) and gamma glutamyl transferase (GGT) activities, calcium, chloride, cholesterol, glucose, and total protein concentrations, and increases in plasma urea, uric acid, and phosphorus concentrations. Plasma electrophoresis endpoints (pre-albumin, albumin, alpha-2 globulin, beta globulin, and gamma globulin concentrations and albumin: globulin ratios) were decreased in orally dosed birds. Birds with external oil had increases in urea, creatinine, uric acid, creatine kinase (CK), glutamate dehydrogenase (GLDH), phosphorus, calcium, chloride, potassium, albumin, alpha-1 globulin and alpha-2 globulin. Decreases were observed in AST, beta globulin and glucose. WBC also differed between treatments; however, this was in part driven by monocytosis present in the externally oiled birds prior to oil treatment

Testing of an oral dosing technique for double-crested cormorants, \u3ci\u3ePhalacocorax auritus\u3c/i\u3e, laughing gulls, \u3ci\u3eLeucophaeus atricilla\u3c/i\u3e, homing pigeons, \u3ci\u3eColumba livia\u3c/i\u3e, and western sandpipers, \u3ci\u3eCalidris mauri\u3c/i\u3e, with artificially weather MC252 oil

Scoping studies were designed to determine if double-crested cormorants (Phalacocorax auritus), laughing gulls (Leucophaues atricilla), homing pigeons (Columba livia) and western sandpipers (Calidris mauri) that were gavaged with a mixture of artificially weathered MC252 oil and food for either a single day or 4–5 consecutive days showed signs of oil toxicity. Where volume allowed, samples were collected for hematology, plasma protein electrophoresis, clinical chemistry and electrolytes, oxidative stress and organ weigh changes. Double-crested cormorants, laughing gulls and western sandpipers all excreted oil within 30 min of dose, while pigeons regurgitated within less than one hour of dosing. There were species differences in the effectiveness of the dosing technique, with double-crested cormorants having the greatest number of responsive endpoints at the completion of the trial. Statistically significant changes in packed cell volume, white cell counts, alkaline phosphatase, alanine aminotransferase, creatine phosphokinase, gamma glutamyl transferase, uric acid, chloride, sodium, potassium, calcium, total glutathione, glutathione disulfide, reduced glutathione, spleen and liver weights were measured in double-crested cormorants. Homing pigeons had statistically significant changes in creatine phosphokinase, total glutathione, glutathione disulfide, reduced glutathione and Trolox equivalents. Laughing gulls exhibited statistically significant decreases in spleen and kidney weight, and no changes were observed in any measurement endpoints tested in western sandpipers

Heterogeneity and Strategic Choices: The Case of Stock Repurchases

Strategic decisions are fundamentally tough choices. Theory suggests that managers are likely to display bounded rationality. Empirics on the other hand assume rationality in choice behavior. Recognizing this inherent disconnect between theory and empirics, we try to account for behavioral biases using a theoretically consistent choice model. The traditional approach to modeling strategic choice has been to use discrete choice models and make inference on the conditional mean effects. We argue that the conditional mean effect does not capture behavioral biases. The focus should be on the conditional variance. Explicitly modeling the conditional variance (in the discrete choice framework) provides us with valuable information on individual level variation in decision-making. We demonstrate the effect of ignoring the role of variance in choice modeling in the context of firm’s decisions to conduct open market repurchases. We show that when taking into account the heterogeneity in choices, manager’s choices of conducting open market repurchases displays considerable heterogeneity and that not accounting for such heterogeneity might lead to wrong conclusions on the mean effects

Norovirus Regulation of the Innate Immune Response and Apoptosis Occurs via the Product of the Alternative Open Reading Frame 4

Small RNA viruses have evolved many mechanisms to increase the capacity of their short genomes. Here we describe the identification and characterization of a novel open reading frame (ORF4) encoded by the murine norovirus (MNV) subgenomic RNA, in an alternative reading frame overlapping the VP1 coding region. ORF4 is translated during virus infection and the resultant protein localizes predominantly to the mitochondria. Using reverse genetics we demonstrated that expression of ORF4 is not required for virus replication in tissue culture but its loss results in a fitness cost since viruses lacking the ability to express ORF4 restore expression upon repeated passage in tissue culture. Functional analysis indicated that the protein produced from ORF4 antagonizes the innate immune response to infection by delaying the upregulation of a number of cellular genes activated by the innate pathway, including IFN-Beta. Apoptosis in the RAW264.7 macrophage cell line was also increased during virus infection in the absence of ORF4 expression. In vivo analysis of the WT and mutant virus lacking the ability to express ORF4 demonstrated an important role for ORF4 expression in infection and virulence. STAT1-/- mice infected with a virus lacking the ability to express ORF4 showed a delay in the onset of clinical signs when compared to mice infected with WT virus. Quantitative PCR and histopathological analysis of samples from these infected mice demonstrated that infection with a virus not expressing ORF4 results in a delayed infection in this system. In light of these findings we propose the name virulence factor 1, VF1 for this protein. The identification of VF1 represents the first characterization of an alternative open reading frame protein for the calicivirus family. The immune regulatory function of the MNV VF1 protein provide important perspectives for future research into norovirus biology and pathogenesis

The Earth: Plasma Sources, Losses, and Transport Processes

This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed