1,040 research outputs found
Estimating the benefits of traffic calming on through routes: A choice expermiment approach
Excessive speed is a major contributory factor in a large proportion of deaths and serious injuries on British roads. One approach to tackling the speeding problem is the use of traffic calming measures as a means of enforcing speed restrictions along roads running through populated areas. But speed reduction is only one of the benefits of traffic calming. This paper reports the results of a series of choice experiments that were used to investigate the willingness to pay (WTP) of a sample of local residents in three English towns for traffic calming measures that would achieve a range of reductions in speed, noise and community severance. Utility difference indices are estimated from logit models based on responses to the choice experiments. These revealed that local people had a positive WTP for a reduction in the negative impacts of road traffic and for more attractive, rather than basic, designs of the traffic calming measures. Some specifications of the logit model corroborate the hypothesis that WTP for reducing the negative impacts of traffic calming is lower for local households living outside visible and audible range of the road
Finite temperature bosonization
Finite temperature properties of a non-Fermi liquid system is one of the most
challenging probelms in current understanding of strongly correlated electron
systems. The paradigmatic arena for studying non-Fermi liquids is in one
dimension, where the concept of a Luttinger liquid has arisen. The existence of
a critical point at zero temperature in one dimensional systems, and the fact
that experiments are all undertaken at finite temperature, implies a need for
these one dimensional systems to be examined at finite temperature.
Accordingly, we extended the well-known bosonization method of one dimensional
electron systems to finite temperatures. We have used this new bosonization
method to calculate finite temperature asymptotic correlation functions for
linear fermions, the Tomonaga-Luttinger model, and the Hubbard model.Comment: REVTex, 48 page
Derivation of the Blackbody Radiation Spectrum from a Natural Maximum-Entropy Principle Involving Casimir Energies and Zero-Point Radiation
By numerical calculation, the Planck spectrum with zero-point radiation is
shown to satisfy a natural maximum-entropy principle whereas alternative
choices of spectra do not. Specifically, if we consider a set of
conducting-walled boxes, each with a partition placed at a different location
in the box, so that across the collection of boxes the partitions are uniformly
spaced across the volume, then the Planck spectrum correspond to that spectrum
of random radiation (having constant energy kT per normal mode at low
frequencies and zero-point energy (1/2)hw per normal mode at high frequencies)
which gives maximum uniformity across the collection of boxes for the radiation
energy per box. The analysis involves Casimir energies and zero-point radiation
which do not usually appear in thermodynamic analyses. For simplicity, the
analysis is presented for waves in one space dimension.Comment: 11 page
Parque Estadual da Ilha Grande ameaças ambientais e diretrizes para conservação
O Parque Estadual da Ilha Grande é somente uma parte (5.594 hectares) de toda a ilha (19.300 hectares) localizada na costa sul do Estado do Rio de Janeiro, entre as cidades de Mangaratiba e Angra dos Reis. Aproximadamente a metade da área do Parque (47%) é coberta por floresta densa, ombrófila, de Mata Atlântica. A mata secundária, em processo de regeneração por sucessão ecológica, está perto da maturidade (43%) e o restante (10%) é composto por áreas antropizadas (1%), afloramentos rochosos com vegetação herbácea (7%), restingas, manguezais e praias (2%). A fauna está bem representada, mas já mostra sinais de degradação com a presença de espécies introduzidas. A análise conduzida sobre o grau de ameaças mostrou que a floresta ombrófila densa está relativamente bem conservada, enquanto a mata secundária, as restingas e mangues e a vegetação herbácea dos terrenos rochosos (e suas respectivas faunas) estão categorizadas como vulneráveis. A área onde há ocupação humana é categorizada como ameaçada. Contraditoriamente, a maior ameaça à biodiversidade local em suas unidades de paisagens é o turismo. Uma vez que a costa onde se localiza a Ilha Grande tem alto valor cênico (conhecida como costa verde pelo constraste entre o mar e o verde da Mata Atlântica que cobre a Serra do Mar), o turismo tem alto potencial para se tornar o meio de atingir a sustentabilidade econômica para conservação. No entanto, por causa do turismo desorganizado e sem controle hoje em prática, com visitantes em número superior à capacidade de suporte na alta estação, a proliferação de hotéis, pousadas e acampamentos e o conseqüente esgoto a céu aberto, depósito de lixo e outras atividades prejudiciais à biodiversidade são as principais ameaças. _______________________________________________________________________________ ABSTRACTThe State Park of Ilha Grande is only a part (5,594 hectares) of the entire island (19,300 hectares) which is located off the south coast of Rio de Janeiro state, between the cities of Mangaratiba and Angra dos Reis. Approximately half of the Park area (47%) is covered by dense Atlantic forest. The secondary forest growth is in a process of ecological succession close to attaining maturity (43%) and the remaining part (10%) is composed of human-altered areas (1%), rocky outcrops with herbaceous vegetation (7%), mangroves and beaches (2%). The fauna is well represented but already shows signs of degradation with introduced species. The analysis of the degree of threat has shown that the dense forest habitat has a relatively stable status of conservation while the secondary forest, the mangrove and the herbaceous vegetation on rocky outcrops (and their fauna) are categorized as vulnerable. The area altered by human occupation is considered threatened. Since the coastal area where Ilha Grande is located is well known for its beautiful scenery (known as the green coast, because of the contrast between the ocean and the Atlantic forest covering the Serra do Mar mountain chain). There is a strong possibility for tourism to become the means in which to achieve economic sustainability for conservation. Contradictorily, tourism is also the major threat to local biodiversity and its landscape units. Because tourism is not organized and controlled, during high season the numbers grow above local capacity, giving rise to a proliferation of hotels, guesthouses and camping grounds. The resulting untreated open sewage, random garbage disposal and other harmful activities form the major threats to biodiversity
On the Second Law of thermodynamics and the piston problem
The piston problem is investigated in the case where the length of the
cylinder is infinite (on both sides) and the ratio is a very small
parameter, where is the mass of one particle of the gaz and is the mass
of the piston. Introducing initial conditions such that the stochastic motion
of the piston remains in the average at the origin (no drift), it is shown that
the time evolution of the fluids, analytically derived from Liouville equation,
agrees with the Second Law of thermodynamics.
We thus have a non equilibrium microscopical model whose evolution can be
explicitly shown to obey the two laws of thermodynamics.Comment: 29 pages, 9 figures submitted to Journal of Statistical Physics
(2003
Grain Surface Models and Data for Astrochemistry
AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions
Theoretical study of the absorption spectra of the sodium dimer
Absorption of radiation from the sodium dimer molecular states correlating to
Na(3s)-Na(3s) is investigated theoretically. Vibrational bound and continuum
transitions from the singlet X Sigma-g+ state to the first excited singlet A
Sigma-u+ and singlet B Pi-u states and from the triplet a Sigma-u+ state to the
first excited triplet b Sigma-g+ and triplet c Pi-g states are studied
quantum-mechanically. Theoretical and experimental data are used to
characterize the molecular properties taking advantage of knowledge recently
obtained from ab initio calculations, spectroscopy, and ultra-cold atom
collision studies. The quantum-mechanical calculations are carried out for
temperatures in the range from 500 to 3000 K and are compared with previous
calculations and measurements where available.Comment: 19 pages, 8 figures, revtex, eps
Ice chemistry in embedded young stellar objects in the Large Magellanic Cloud
We present spectroscopic observations of a sample of 15 embedded young
stellar objects (YSOs) in the Large Magellanic Cloud (LMC). These observations
were obtained with the Spitzer Infrared Spectrograph (IRS) as part of the
SAGE-Spec Legacy program. We analyze the two prominent ice bands in the IRS
spectral range: the bending mode of CO_2 ice at 15.2 micron and the ice band
between 5 and 7 micron that includes contributions from the bending mode of
water ice at 6 micron amongst other ice species. The 5-7 micron band is
difficult to identify in our LMC sample due to the conspicuous presence of PAH
emission superimposed onto the ice spectra. We identify water ice in the
spectra of two sources; the spectrum of one of those sources also exhibits the
6.8 micron ice feature attributed to ammonium and methanol. We model the CO_2
band in detail, using the combination of laboratory ice profiles available in
the literature. We find that a significant fraction (> 50%) of CO_2 ice is
locked in a water-rich component, consistent with what is observed for Galactic
sources. The majority of the sources in the LMC also require a pure-CO_2
contribution to the ice profile, evidence of thermal processing. There is a
suggestion that CO_2 production might be enhanced in the LMC, but the size of
the available sample precludes firmer conclusions. We place our results in the
context of the star formation environment in the LMC.Comment: Minor corrections to Table 2. Accepted for publication in ApJ, 66
pages, 9 figures (some in color), 4 table
Introducing willingness-to-pay for noise changes into transport appraisal: an application of benefit transfer.
Numerous research studies have elicited willingness-to-pay values for transport-related noise, however, in many industrialised countries including the UK, noise costs and benefits are still not incorporated into appraisals for most transport projects and policy changes (Odgaard et al, 2005; Grant-Muller et al, 2001). This paper describes the actions recently taken in the UK to address this issue, comprising: primary research based on the city of Birmingham; an international review of willingness-to-pay evidence; development of values using benefit transfers over time and locations; and integration with appraisal methods. Amongst the main findings are: that the willingness-to-pay estimates derived for the UK are broadly comparable with those used in appraisal elsewhere in Europe; that there is a case for a lower threshold at
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45dB(A)Leq,18hr1 rather than the more conventional 55dB(A); and that values per dB(A) increase with the noise level above this threshold. There are significant issues over the valuation of rail versus road noise, the neglect of non-residential noise and the valuation of high noise levels in different countries. Conclusions are drawn regarding the feasibility of noise valuation based on benefit transfers in the UK and elsewhere, and future research needs in this field are discussed
The discovery of potent, selective, and reversible inhibitors of the house dust mite peptidase allergen Der p 1: an innovative approach to the treatment of allergic asthma.
Blocking the bioactivity of allergens is conceptually attractive as a small-molecule therapy for allergic diseases but has not been attempted previously. Group 1 allergens of house dust mites (HDM) are meaningful targets in this quest because they are globally prevalent and clinically important triggers of allergic asthma. Group 1 HDM allergens are cysteine peptidases whose proteolytic activity triggers essential steps in the allergy cascade. Using the HDM allergen Der p 1 as an archetype for structure-based drug discovery, we have identified a series of novel, reversible inhibitors. Potency and selectivity were manipulated by optimizing drug interactions with enzyme binding pockets, while variation of terminal groups conferred the physicochemical and pharmacokinetic attributes required for inhaled delivery. Studies in animals challenged with the gamut of HDM allergens showed an attenuation of allergic responses by targeting just a single component, namely, Der p 1. Our findings suggest that these inhibitors may be used as novel therapies for allergic asthma
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