Utility in Willingness to Pay Space: A Tool to Address Confounding Random Scale Effects in Destination Choice to the Alps

We compare two approaches for estimating the distribution of consumers' willingness to pay (WTP) in discrete choice models. The usual procedure is to estimate the distribution of the utility coefficients and then derive the distribution of WTP, which is the ratio of coefficients. The alternative is to estimate the distribution of WTP directly. We apply both approaches to data on site choice in the Alps. We find that the alternative approach fits the data better, reduces the incidence of exceedingly large estimated WTP values, and provides the analyst with greater control in specifying and testing the distribution of WTP. © 2008 Agricultural and Applied Economics Association.

The legacy of past manuring practices on soil contamination in remote rural areas

This paper demonstrates that there can be a legacy of contamination on former arable land in remote rural areas as a result of past manuring practices. In the first part of the study four farms abandoned in the late 19th to mid-20th century were investigated with samples collected from residual material in domestic hearths, the midden heaps, kailyards (walled garden for vegetables), infields (intensively managed arable land) and outfields (less intensively managed land for cropping or grazing). Consistent sequences in concentration values were found for such elements as Pb, Zn, Cu and P in the order hearth>midden>kailyard>infield>outfield. Such patterns can in part be explained in terms of atmospheric deposition on peat and turf which were subsequently burnt in hearths to result in enhanced elemental concentrations. The ash then was deposited in midden heaps and subsequently on kailyards or infields. In the second part, microanalytical results from St. Kilda are discussed. Enhanced loadings of Pb and Zn were found in the old arable land. The highest levels of Zn were found in small fragments of carbonised and humified material and bone fragments; in contrast Pb tended to be more uniformly distributed. Seabird waste was extensively applied to the arable land and some of the Zn may have accumulated in the soil by this pathway. The retention of Zn in bone is likely to have been very minor given the rarity of bone fragments as evident in thin sections (0.3%); this compares with 6.8% for black carbonised particles which are likely to provide the main storage sites for Zn.

Estimates of peer effects in adolescent smoking across twenty six European countries

Although it is widely believed that one of the key factors influencing whether an adolescent smokes or not is the smoking behaviour of his or her peers, empirical evidence on the magnitude of such peer effects, and even on their existence, is mixed. This existing evidence comes from a range of studies using a variety of country-specific data sources and a variety of identification strategies. This paper exploits a rich source of individual level, school-based, survey data on adolescent substance use across countries - the 2007 European Schools Survey Project on Alcohol and Other Drugs - to provide estimates of peer effects between classmates in adolescent smoking for 75,000 individuals across 26 European countries, using the same methods in each case. The results suggest statistically significant peer effects in almost all cases. These peer effects estimates are large: on average across countries, the probability that a 'typical' adolescent smokes increases by between.31 and.38 percentage points for a one percentage point increase in the proportion of classmates that smoke. Further, estimated peer effects in adolescent smoking are stronger intra-gender than inter-gender. They also vary across countries: in Belgium, for example, a one percentage point increase in reference group smoking is associated with a.16 to.27 percentage point increase in own smoking probability; in the Netherlands the corresponding increase is between.42 and.59 percentage points. © 2011 Elsevier Ltd.

Local-field and excitonic effects in the optical response of alpha-alumina

This paper introduces key ingredients of the dielectric response of a-alumina that go beyond an independent-particle (IP) treatment of the valence-electron excitations. The optical-response functions were calculated from first-principles both at the Bethe-Salpeter and the random-phase approximation (RPA) levels. Excitonic effects obtained within the Bethe-Salpeter framework were found essential for reproducing the low-energy part of the experimental spectra (below 15 eV) and the bound exciton in particular. For higher energies, local-field effects introduced through the RPA modified considerably the IP results and provided a satisfactory account of the reflectivity spectra and of the position and shape of the dominant bulk plasmon resonance in the electron energy-loss spectra.

Orientation effects in copper phthalocyanine films studied by electron paramagnetic resonance spectroscopy

The metallo-phthalocyanines (MPcs) are an interesting group of organic semiconductor materials for applications such as large area solar cells due to their optoelectronic properties coupled with the possibility of easily and cheaply fabricating thin films of MPcs [1, 2]. As for organic semiconductors in general, many of the interesting properties of the MPcs such as magnetism, light absorption and charge transport, are highly anisotropic [2, 3]. To maximise the efficiency of a device based on these materials it is therefore important to study their molecular orientation in films and to assess the influence of different growth conditions and substrate treatments.
X-ray diffraction is a well established and powerful technique for studying texture (and hence molecular orientation) in crystalline materials, but it cannot provide any information about amorphous or nanocrystalline films. In electron paramagnetic resonance (EPR) spectroscopy the signal comes from the spin of unpaired electrons in the material. This technique therefore does not require the sample to be crystalline. It works for any sample with paramagnetic centres such as the MPcs where the unpaired electrons are contributed by the metal. In this paper we present a continuous-wave X-band EPR study using the anisotropy of the EPR spectrum of CuPc [4] to determine the orientation effects in different types of CuPc films. From these measurements we gain insight into the molecular arrangement of films with different spin concentrations, and apply our technique to the study of molecular orientation in photovoltaic cells.

Orientation effects in copper phthalocyanine films studied by EPR

Organic semiconductors have already found commercial applications in for example displays with organic light-emitting diodes (OLEDs) and great advances are also being made in other areas, such as organic field-effect transistors and organic solar cells. [1] The organic semicondutor group of materials known as metal phthalocyanines (MPc’s) is interesting for applications such as large area solar cells due to their optoelectronic properties coupled with the possibility of easily and cheaply fabricating thin films of MPc’s. [1, 2]

Many of the properties of organic semiconductors, such as magnetism, light absorption and charge transport, show orientational anisotropy. [2, 3] To maximise the efficiency of a device based on these materials it is therefore important to study the molecular orientation in films and to assess the influence of different growth conditions and substrate treatments. X-ray diffraction is a well established and powerful technique for studying texture (and hence molecular orientation)_in crystalline materials, but cannot provide any information about amorphous or nanocrystalline films. In this paper we present a continuous wave X-band EPR study using the anisotropy of the CuPc EPR spectrum [4] to determine the orientation effects in different types of CuPc films. From these measurements we also gain insight into the molecular arrangement of films of CuPc mixed with the isomorphous H2Pc and with C60 in films typical of real solar cell systems.

Ensemble effects in the coupling of acetylene to benzene on a bimetallic surface: A study with Pd{111}/Au

Acetylene coupling to benzene on the Pd(lll) surface is greatly enhanced by the presence of catalytically inert Au atoms. LEED and Auger spectroscopy show that progressive annealing of Au overlayers on Pd(lll) leads to the formation of a series of random surface alloys with continuously varying composition. Cyclization activity is a strong function of surface composition-the most efficient catalyst corresponds to a surface of composition similar to 85% Pd. CO TPD and HREELS data show that acetylene cyclization activity is not correlated with the availability of singleton Pd atoms, nor just with the presence of 3-fold pure Pd sites-the preferred chemisorption site for C2H2 on Pd{111}. The data can be quantitatively rationalized in terms of a simple model in which catalytic activity is dominated by Pd6Au and Pd-7 surface ensembles, allowance being made for the known degree to which pure Pd{111} decomposes the reactant and product molecules.

Two-Ray Modeling of Recombination Effects in the Presence of a Phase Conjugation Array

This article describes by means of a simple model how signal recombination effects behave under the influence of phase conjugating retrodirective array (RDA) technology. A two-ray ground reflection model is used to predict the operational advantages of RDA technology in multipath rich environments. The simulation results show that advantageous signal recombination occurs due to automatic self-phasing. As the number of elements in the RDA increases, the fading effect normally observed due to out of phase multipath signal is mitigated to the extent that the system approaches that of one operating in a free space environment. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1987–1989, 2013

Peer effects in UK adolescent substance use: Never mind the classmates?

This article estimates peer influences on the alcohol, tobacco and cannabis use of UK adolescents. We present evidence of large, positive and statistically significant peer effects in all three behaviours when classmates are taken as the reference group. We also find large, positive and statistically significant associations between own substance use and friends' substance use. When both reference groups are considered simultaneously, the influence of classmates either disappears or is much reduced, whereas the association between own and friends' behaviours does not change. The suggestion is that classmate behaviour is primarily relevant only inasmuch as it proxies for friends' behaviour.

Pomegranate polyphenols lower lipid peroxidation in adults with type 2 diabetes but have no effects in healthy volunteers:a pilot study

Aims. To examine the antioxidant and anti-inflammatory effects of pomegranate polyphenols in obese patients with type 2 diabetes (T2DM) (n = 8) and in healthy nondiabetic controls (n = 9). Methods. Participants received 2 capsules of pomegranate polyphenols (POMx, 1 capsule = 753?mg polyphenols) daily for 4 weeks. Blood draws and anthropometrics were performed at baseline and at 4 weeks of the study. Results. Pomegranate polyphenols in healthy controls and in T2DM patients did not significantly affect body weight and blood pressure, glucose and lipids. Among clinical safety profiles, serum electrolytes, renal function tests, and hematological profiles were not significantly affected by POMx supplementation. However, aspartate aminotransferase (AST) showed a significant increase in healthy controls, while alanine aminotransferase (ALT) was significantly decreased in T2DM patients at 4 weeks (P <0.05), though values remained within the normal ranges. Among the biomarkers of lipid oxidation and inflammation, oxidized LDL and serum C-reactive protein (CRP) did not differ at 4 weeks in either group, while pomegranate polyphenols significantly decreased malondialdehyde (MDA) and hydroxynonenal (HNE) only in the diabetic group versus baseline (P <0.05). Conclusions. POMx reduces lipid peroxidation in patients with T2DM, but with no effects in healthy controls, and specifically modulates liver enzymes in diabetic and nondiabetic subjects. Larger clinical trials are merited.

Predator cue studies reveal strong trait-mediated effects in communities despite variation in experimental designs

Nonconsumptive or trait-mediated effects of predators on their prey often outweigh density-mediated interactions where predators consume prey. For instance, predator presence can alter prey behaviour, physiology, morphology and/or development. Despite a burgeoning literature, our ability to identify general patterns in prey behavioural responses may be influenced by the inconsistent methodologies of predator cue experiments used to assess trait-mediated effects. We therefore conducted a meta-analysis to highlight variables (e.g. water type, predator husbandry, exposure time) that may influence invertebrate prey's behavioural responses to fish predator cues. This revealed that changes in prey activity and refuge use were remarkably consistent overall, despite wide differences in experimental methodologies. Our meta-analysis shows that invertebrates altered their behaviour to predator cues of both fish that were fed the focal invertebrate and those that were fed other prey types, which suggests that invertebrates were not responding to specific diet information in the fish cues. Invertebrates also altered their behaviour regardless of predator cue addition regimes and fish satiation levels. Cue intensity and exposure time did not have significant effects on invertebrate behaviour. We also highlight that potentially confounding factors, such as parasitism, were rarely recorded in sufficient detail to assess the magnitude of their effects. By examining the likelihood of detecting trait-mediated effects under large variations in experimental design, our study demonstrates that trait-mediated effects are likely to have pervasive and powerful influences in nature.

Pellino3 ubiquitinates RIP2 and mediates Nod2-induced signaling and protective effects in colitis

Mutations that result in loss of function of Nod2, an intracellular receptor for bacterial peptidoglycan, are associated with Crohn's disease. Here we found that the E3 ubiquitin ligase Pellino3 was an important mediator in the Nod2 signaling pathway. Pellino3-deficient mice had less induction of cytokines after engagement of Nod2 and had exacerbated disease in various experimental models of colitis. Furthermore, expression of Pellino3 was lower in the colons of patients with Crohn's disease. Pellino3 directly bound to the kinase RIP2 and catalyzed its ubiquitination. Loss of Pellino3 led to attenuation of Nod2-induced ubiquitination of RIP2 and less activation of the transcription factor NF-?B and mitogen-activated protein kinases (MAPKs). Our findings identify RIP2 as a substrate for Pellino3 and Pellino3 as an important mediator in the Nod2 pathway and regulator of intestinal inflammation. © 2013 Nature America, Inc. All rights reserved.

A multiconfigurational time-dependent Hartree-Fock method for excited electronic states. II. Coulomb interaction effects in single conjugated polymer chains

Conjugated polymers have attracted considerable attention in the last few decades due to their potential for optoelectronic applications. A key step that needs optimisation is charge carrier separation following photoexcitation. To understand better the dynamics of the exciton prior to charge separation, we have performed simulations of the formation and dynamics of localised excitations in single conjugated polymer strands. We use a nonadiabatic molecular dynamics method which allows for the coupled evolution of the nuclear degrees of freedom and of multiconfigurational electronic wavefunctions. We show the relaxation of electron-hole pairs to form excitons and oppositely charged polaron pairs and discuss the modifications to the relaxation process predicted by the inclusion of the Coulomb interaction between the carriers. The issue of charge photogeneration in conjugated polymers in dilute solution is also addressed. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3600404]