Restless and Aloft

Combined media on photographic paper. 90" x 55" Santa Monica Airport Museum

Local Currency Pricing, Foreign Monetary Shocks and Exchange Rate Policy

The implications of local currency pricing (LCP) for monetary regime choice are analysed for a country facing foreign monetary shocks. In this analysis expenditure switching is potentially welfare reducing. This contrasts with the existing LCP literature, which focuses on productivity shocks and thus analyses a world where expenditure switching is welfare enhancing. This paper shows that, when home and foreign producers follow LCP, expenditure switching is absent and a floating rate is preferred by the home country. But when only home producers follow LCP, expenditure switching is present and a fixed rate can be welfare enhancing for the home country.

Congested hubs

Hub congestion is a major problem and a relevant policy issue because it causes delays and many organizational problems at airports that end up implying unpleasant consequences both for air travelers and airlines. In a competitive framework in which carriers choose aircraft size, this paper suggests that airlines schedule too many flights using overly small aircraft, which constitutes a major contributor to congestion. Two- part congestion tolls, accounting for the congestion imposed on other carriers and the congestion imposed on all passengers, are needed to recover e¢ ciency. Finally, we analyze the validity of the results by studying the effects of network size, airport capacity, competition in layover time, and the formation of airline alliances. Keywords: congestion; hub-and-spoke networks; overprovision of frequency; con- gestion internalization; congestion tolls JEL Classiffication Numbers: L13; L2; L93

Agents mòbils i DTN: disseny i implementació d'un protocol d'encaminament en l'entorn PROSES

En aquest projecte s’ha treballat en l’entorn PROSES, on aeroports i avions de l’espai aeri són mules de transport sobre una xarxa DTN. L’objectiu principal és estudiar i simular dos escenaris concrets: l’enviament de notícies des de les torres de control als avions, i l’enviament de canvis de rutes de vol dels avions a un aeroport en qüestió. S’ha simulat el comportament de dos protocols d’encaminament diferents sobre els escenaris creats. Per a realitzar les proves s’ha utilitzat el simulador The ONE, s’ha implementat un nou protocol d’encaminament, s’ha creat un Generador de Mapes i Rutes, i s’han realitzat amb èxit les simulacions.

Ant brood function as life preservers during floods.

Social organisms can surmount many ecological challenges by working collectively. An impressive example of such collective behavior occurs when ants physically link together into floating 'rafts' to escape from flooded habitat. However, raft formation may represent a social dilemma, with some positions posing greater individual risks than others. Here, we investigate the position and function of different colony members, and the costs and benefits of this functional geometry in rafts of the floodplain-dwelling ant Formica selysi. By causing groups of ants to raft in the laboratory, we observe that workers are distributed throughout the raft, queens are always in the center, and 100% of brood items are placed on the base. Through a series of experiments, we show that workers and brood are extremely resistant to submersion. Both workers and brood exhibit high survival rates after they have rafted, suggesting that occupying the base of the raft is not as costly as expected. The placement of all brood on the base of one cohesive raft confers several benefits: it preserves colony integrity, takes advantage of brood buoyancy, and increases the proportion of workers that immediately recover after rafting.

Aerotropolis: an aviation-linked space

This paper examines the conditions allowing the formation of aeropolitan areas as large industrial areas with a high concentration of commercial activities in the proximity of selected airports. We assume that firms deliver their production by plane and land competition takes place among service operators, firms and farmers. Service operators supply facilities that firms can absorb. Our framework identifies a unique land equilibrium characterized by the spatial sequence Airport - Industrial park - Rural area (A-I-R). Aerotropolis-type configurations are associated with the level of transport costs and the degree of intensity of facilities. Keywords: aerotropolis; facilities; bid-rent function. JEL Classification Numbers: L29; L90; R14.

Advantages of digital holographic microscopy for real-time full field absolute phase imaging

Different interferometric techniques were developed last decade to obtain full field, quantitative, and absolute phase imaging, such as phase-shifting, Fourier phase microscopy, Hilbert phase microscopy or digital holographic microscopy (DHM). Although, these techniques are very similar, DHM combines several advantages. In contrast, to phase shifting, DHM is indeed capable of single-shot hologram recording allowing a real-time absolute phase imaging. On the other hand, unlike to Fourier phase or Hilbert phase microscopy, DHM does not require to record in focus images of the specimen on the digital detector (CCD or CMOS camera), because a numerical focalization adjustment can be performed by a numerical wavefront propagation. Consequently, the depth of view of high NA microscope objectives is numerically extended. For example, two different biological cells, floating at different depths in a liquid, can be focalized numerically from the same digital hologram. Moreover, the numerical propagation associated to digital optics and automatic fitting procedures, permits vibrations insensitive full- field phase imaging and the complete compensation for a priori any image distortion or/and phase aberrations introduced for example by imperfections of holders or perfusion chamber. Examples of real-time full-field phase images of biological cells have been demonstrated. ©2008 COPYRIGHT SPIE

Persistence of retinal function after intravitreal melphalan injection for retinoblastoma.

BACKGROUND: The risk/benefit profile of intravitreal melphalan injection for treatment of active vitreous seeds in retinoblastoma remains uncertain. We report clinical and electroretinography results after 6 months of one patient who has shown a favorable initial clinical response to intravitreal melphalan injections for treatment of refractory vitreous seeds. METHODS: Clinical case report. PATIENT: The patient presented at age 17 months with bilateral retinoblastoma [OD: International Classification (ICRB) group E, Reese-Ellsworth (R-E) class Vb; OS: ICRB D, R-E Vb] with no known prior family history. The right eye was enucleated primarily. The patient received systemic chemotherapy and extensive local treatment to the left eye. Ten months later, she presented with recurrent disease, including fine, diffuse vitreous seeds. Tumor control was established with intra-arterial chemotherapy and local treatment. Subsequent recurrence was treated with further intra-arterial chemotherapy, local treatment, and plaque radiotherapy with iodine-125. Persistent free-floating spherical vitreous seeds were treated with 4 cycles of intravitreal melphalan injection via the pars plana, with doses of 30, 30, 30, and 20 μg. RESULTS: After 6 months of follow-up, the left eye remained free of active tumor. Visual acuity was 20/40. Photopic ERGs amplitudes were unchanged compared with those recorded prior to the intravitreal injection treatments. CONCLUSIONS: Intravitreal melphalan injection for refractory spherical vitreous seeds of retinoblastoma with favorable tumor response is compatible with good central visual acuity and preservation of retinal function as indicated by photopic ERG recordings.

Winter survival of immature instars of Mansonia indubitans Dyar & Shannon and Mansonia titillans Walker (Diptera: Culicidae), in Buenos Aires, Argentina

We conducted a whole year research on the ecology of Mansonia indubitans and Ma. titillans in Macáes Pond, Costanera Sur Reserve, Buenos Aires, Argentina. The usage of different floating plants by immature instars and their overwintering was analized. The percentage of usage of the available floating macrophytes (Pistia, Limnobium, and Salvinia) by the larvae and pupae was studied. Also, we defined positivity (P+) as the percentage of plants with immature instars for each plant genus on a monthly basis. Ma. immature instars were captured throughout the year and Pistia was the resource most commonly exploited by the mosquitoes. The percentage of fourth-instar larvae and pupae on Pistia roots with respect to total immature instars captured was assessed on a monthly and seasonal basis. The proportion of fourth-instar larvae and pupae from both species of Mansonia on water lettuce roots, showed significant differences between months and seasons. Our results suggest that the populations of Ma. indubitans and Ma. titillans in Macáes Pond, survive during winter mainly as fourth-instar larvae.

Estudi de comparació de rendiment de Benchmark multicore i multithreading amb OpenMP 2.5 i OpenMP 3.0

Estudi comparatiu amb benchmark del rendiment en dues plataformes multicore multithreading de diferents modalitats de paral·lelització de multiplicacions de matrius de nombres enters i de nombres en coma flotant mitjançant el model de memòria compartida OpenMP versió 2.5 i OpenMP versió 3.0.

Análisis de la demanda turística en vuelos de bajo coste: Turista de negocios vs turista de ocio

L’estudi pretén establir si el turista de negocis es pot considerar un segment de mercat diferenciat del turista d’oci, ara que els vols de baix cost augmenten. Per això s’analitza una mostra de turistes estrangers en vols de baix cost a l’aeroport de Girona al 2005. Els resultats apunten a unes característiques diferencials en la demanada del turista de negocis, com són la durada de l’estança,i el tipus d’allotjament, però no s’aprecien diferències en la valoració del preu i de l’hora del vol, ni en la tipologia del bitllet

Estimation of the real population and its impact on the utilisation of healthcare services in Mediterranean resort regions: an ecological study.

BACKGROUND The demographic structure has a significant influence on the use of healthcare services, as does the size of the population denominators. Very few studies have been published on methods for estimating the real population such as tourist resorts. The lack of information about these problems means there is a corresponding lack of information about the behaviour of populational denominators (the floating population or tourist load) and the effect of this on the use of healthcare services. The objectives of the study were: a) To determine the Municipal Solid Waste (MSW) ratio, per person per day, among populations of known size; b) to estimate, by means of this ratio, the real population in an area where tourist numbers are very significant; and c) to determine the impact on the utilisation of hospital emergency healthcare services of the registered population, in comparison to the non-resident population, in two areas where tourist numbers are very significant. METHODS An ecological study design was employed. We analysed the Healthcare Districts of the Costa del Sol and the island of Menorca. Both are Spanish territories in the Mediterranean region. RESULTS In the two areas analysed, the correlation coefficient between the MSW ratio and admissions to hospital emergency departments exceeded 0.9, with p < 0.001. On the basis of MSW generation ratios, obtained for a control zone and also measured in neighbouring countries, we estimated the real population. For the summer months, when tourist activity is greatest and demand for emergency healthcare at hospitals is highest, this value was found to be double that of the registered population. CONCLUSION The MSW indicator, which is both ecological and indirect, can be used to estimate the real population in areas where population levels vary significantly during the year. This parameter is of interest in planning and dimensioning the provision of healthcare services.

Intraovarian sperm storage in Helicolenus dactylopterus dactylopterus fertilitzation, crypt formation and maintenance of stored sperm

The females of the bluemouth rockfish, Helicolenus dactylopterus dactylopterus (DelaRoche, 1809), store sperm within their ovaries for periods of up to 10 months. Twenty six females with standard lengths between 152 and 257 mm and six males with standard lengths between 253 and 209 mm were caught storage crypts with stored spermatozoa and to describe their evolution over the year. After internal fertilization and once sperm reaches the ovary, a crypt forms probably by an epithelial inclusion at the base of the lamellae of one or several spermatozoa groups that are floating freely in the interlamellar space of the ovarian lumen. Stored spermatozoa have a large cytoplasm bag surrounding their heads. This bag could serve as a nutritive reservoir during the long storage period. Many desmosonal and tight junctions between the crypt cells ensure tha male sex cells are protected against the female immune system

A quantum molecular similarity analysis of changes in molecular electron density caused by basis set flotation and electric field application

Quantum molecular similarity (QMS) techniques are used to assess the response of the electron density of various small molecules to application of a static, uniform electric field. Likewise, QMS is used to analyze the changes in electron density generated by the process of floating a basis set. The results obtained show an interrelation between the floating process, the optimum geometry, and the presence of an external field. Cases involving the Le Chatelier principle are discussed, and an insight on the changes of bond critical point properties, self-similarity values and density differences is performed

Airline Consolidation and the Distribution of Traffic between Primary and Secondary Hubs

Several airline consolidation events have recently been completed both in Europe and in the United States. The model we develop considers two airlines operating hub-and-spoke networks, using different hubs to connect the same spoke airports. We assume the airlines to be vertically differentiated, which allows us to distinguish between primary and secondary hubs. We conclude that this differentiation in air services becomes more accentuated after consolidation, with an increased number of flights being channeled through the primary hub. However, congestion can act as a brake on the concentration of flight frequency in the primary hub following consolidation. Our empirical application involves an analysis of Delta s network following its merger with Northwest. We find evidence consistent with an increase in the importance of Delta s primary hubs at the expense of its secondary airports. We also find some evidence suggesting that the carrier chooses to divert traffic away from those hub airports that were more prone to delays prior to the merger, in particular New York s JFK airport. Keywords: primary hub; secondary hub; airport congestion; airline consolidation; airline networks JEL Classi fication Numbers: D43; L13; L40; L93; R4