Hub Premium, Airport Dominance and Market Power in the European Airline Industry.

Using evidence from an original dataset of more than 12 million fares, this study sheds light on two issues relating to the pricing behaviour of the main European airlines: 1) the extent to which an airline’s dominant position at the origin airport, at the route and the city-pair level affects the airlines’ market power; 2) whether fares follow a monotonic time path consistent with the pursuing of an inter-temporal price discrimination strategy. Our estimates reveal that enjoying a dominant position within a route is conducive to higher fares, possibly because of the limited size of many “natural monopoly” routes that facilitate the incumbent’s engagement in a limit pricing strategy. On the contrary, a larger share within a city-pair does not seem to facilitate the exercise of market power, thereby suggesting the existence of a large degree of substitutability between the routes in a city-pair.on-line pricing; price discrimination; dispersion; yield management.

Pricing strategies by European traditional and low cost airlines. Or, when is it the best time to book on line?

It is often assumed that the airlines’ fares increase monotonically over time, peaking a few days before the departure. Using fares for about 650 thousand flights operated by both Low-Cost and Full Service Carriers, we show several instances in which the monotonic property does not hold. We also show that the volatility of fares increase in the last four weeks before departure, which is the period when the airlines can formulate a better prediction for a flight’s load factor. Finally, especially within the last two weeks, Full Service Carriers may offer lower fares than those posted by Low Cost Carriers.on-line pricing; price discrimination; dispersion; yield management.

Pricing strategies by European Low Cost Carriers.

We introduce an on-line pricing tactic where airlines post, at the same time and for the same flight, fares in different currencies that violate the law of One Price. Unexpectedly for an on-line market, we find that price discrimination may be accompanied by arbitrage opportunities and that both tend to persist before a flight’s departure. We find discrimination to be of a competitive type, although arbitrage opportunities are more likely in concentrated routes. Finally, the evidence suggests that discrimination may be used to manage stochastic demand.on-line pricing; price discrimination; Law of One Price; sample selection; dispersion; airlines, exchange rate.

Foraminiferal biotopes in a shallow continental shelf environment: Esperance Bay (southwestern Australia)

The Great Australian Bight is a large carbonate cold water environment located on the central and western portions of the southern Australia. Seagrasses (Posidonia sp.) and macroalgae benthic habitats are widely distributed in the shallow water environment of southern Australia, contributing to the carbonate factory. This study investigated the distribution of modern benthic foraminiferal assemblages in the microtidal wave-dominated inner-shelf of Esperance Bay (southwestern Australia), that lies on the western margin of the Great Australian Bight. Benthic foraminifera were taxonomically identified and biotic parameters (species richness, density, Fisher-α index, Shannon–Weaver index, dominance) were calculated. Multivariate analyses (Hierarchical Cluster Analysis, Principal Component Analysis) were performed to understand foraminiferal distribution in the context of environmental conditions. Four main Foraminiferal assemblages have been recognized: (I) a nearshore assemblage of dense seagrass meadow, dominated by Lamellodiscorbis dimidiatus, Elphidium craticulatum, Elphidium crispum, Cibicidoides lobatulus, II) a second assemblage associated with unvegetated seabed (approximately 30 m depth) with Lamellodiscorbis dimidiatus, Elphidium crispum, Quinqueloculina disparilis, III) a third assemblage in the central sector of the bay, characterized by a discontinuous and mixed seagrass-algae coverage with Lamellodiscorbis dimidiatus, Elphidium crispum, Elphidium macellum, Cibicides refulgens, and Quinqueloculina poeyana, and IV) an epiphytic assemblage of transitional zone from the coastline to the upper limit of a mixed seagrass-algae meadow, dominated by Elphidium crispum, Chrysalidinella dimorpha, Planulinoides biconcava, Planoglabratella opercularis, Rugobolivinella elegans. The spatial distribution of the four assemblages appears closely related to sediment texture, seagrass cover and depth, but it is also influenced by the shoreface morphology and the hydrodynamic energy. The understanding of the ecological parameters that influence benthic foraminiferal distribution, composition and assemblage structure within seagrass meadows is useful for paleoecological and paleoenvironmental interpretations

Nitrite effect on the phosphorus uptake activity of phosphate accumulating organisms (PAOs) in pilot-scale SBR and MBR reactors

Batch tests were performed to investigate the nitrite effect on the P-uptake of biomass grown in pilot-scale SBR and MBR systems. The results showed that the nitrite has an inhibitory effect on the aerobic P-uptake of the SBR and the MBR biomasses. The degree of inhibition was observed to be 65 % and 37 % at 10 mg NO2-N/ℓ for the SBR and the MBR respectively. Both biomasses were found capable of using nitrite as electron acceptor as effectively as nitrate. Moreover, for the SBR biomass the anoxic P-uptake rate using nitrite was found even higher (60%) than the P-uptake rate with nitrate. From a modelling point of view, the current models require appropriate extensions to describe these various effects of nitrite. Hence, an extension of the ASM2d model has been provided. Prevention of nitrite build-up in full-scale EBPRs will eliminate the nitrite inhibition problem. Alternatively one can adopt a proactive approach in which the aerobic P-uptake phase is replaced with an anoxic P-uptake phase using only nitrite as electron acceptor. Such an approach offers considerable cost savings and enhanced nitrogen and phosphorus removal. This, however, requires further research for experimental validation and testing.Keywords: ASM2d, MBR, modelling, nitrogen and phosphorus removal, nitrite inhibition, polyphosphate accumulating organisms, phosphate uptake, SB

Intracranial V. cholerae Sialidase Protects against Excitotoxic Neurodegeneration

Converging evidence shows that GD3 ganglioside is a critical effector in a number of apoptotic pathways, and GM1 ganglioside has neuroprotective and noötropic properties. Targeted deletion of GD3 synthase (GD3S) eliminates GD3 and increases GM1 levels. Primary neurons from GD3S−/− mice are resistant to neurotoxicity induced by amyloid-β or hyperhomocysteinemia, and when GD3S is eliminated in the APP/PSEN1 double-transgenic model of Alzheimer's disease the plaque-associated oxidative stress and inflammatory response are absent. To date, no small-molecule inhibitor of GD3S exists. In the present study we used sialidase from Vibrio cholerae (VCS) to produce a brain ganglioside profile that approximates that of GD3S deletion. VCS hydrolyzes GD1a and complex b-series gangliosides to GM1, and the apoptogenic GD3 is degraded. VCS was infused by osmotic minipump into the dorsal third ventricle in mice over a 4-week period. Sensorimotor behaviors, anxiety, and cognition were unaffected in VCS-treated mice. To determine whether VCS was neuroprotective in vivo, we injected kainic acid on the 25th day of infusion to induce status epilepticus. Kainic acid induced a robust lesion of the CA3 hippocampal subfield in aCSF-treated controls. In contrast, all hippocampal regions in VCS-treated mice were largely intact. VCS did not protect against seizures. These results demonstrate that strategic degradation of complex gangliosides and GD3 can be used to achieve neuroprotection without adversely affecting behavior

R5-SHIV Induces Multiple Defects in T Cell Function during Early Infection of Rhesus Macaques Including Accumulation of T Reg Cells in Lymph Nodes

Background: HIV-1 is a pathogen that T cell responses fail to control. HIV-1gp120 is the surface viral envelope glycoprotein that interacts with CD4 T cells and mediates entry. HIV-1gp120 has been implicated in immune dysregulatory functions that may limit anti-HIV antigen-specific T cell responses. We hypothesized that in the context of early SHIV infection, immune dysregulation of antigen-specific T-effector cell and regulatory functions would be detectable and that these would be associated or correlated with measurable concentrations of HIV-1gp120 in lymphoid tissues. Methods: Rhesus macaques were intravaginally inoculated with a Clade C CCR5-tropic simian-human immunodeficiency virus, SHIV-1157ipd3N4. HIV-1gp120 levels, antigen-specificity, levels of apoptosis/anergy and frequency and function of Tregs were examined in lymph node and blood derived T cells at 5 and 12 weeks post inoculation. Results/Conclusions: We observed reduced responses to Gag in CD4 and gp120 in CD8 lymph node-derived T cells compared to the peripheral blood at 5 weeks post-inoculation. Reduced antigen-specific responses were associated with higher levels of PD-1 on lymph node-derived CD4 T cells as compared to peripheral blood and uninfected lymph node-derived CD4 T cells. Lymph nodes contained increased numbers of Tregs as compared to peripheral blood, which positively correlated with gp120 levels; T regulatory cell depletion restored CD8 T cell responses to Gag but not to gp120. HIV gp120 was also able to induce T regulatory cell chemotaxis in a dose-dependent, CCR5-mediated manner. These studies contribute to our broader understanding of the ways in which HIV-1 dysregulates T cell function and localization during early infection