Robust Cryptography in the Noisy-Quantum-Storage Model

It was shown in [WST08] that cryptographic primitives can be implemented based on the assumption that quantum storage of qubits is noisy. In this work we analyze a protocol for the universal task of oblivious transfer that can be implemented using quantum-key-distribution (QKD) hardware in the practical setting where honest participants are unable to perform noise-free operations. We derive trade-offs between the amount of storage noise, the amount of noise in the operations performed by the honest participants and the security of oblivious transfer which are greatly improved compared to the results in [WST08]. As an example, we show that for the case of depolarizing noise in storage we can obtain secure oblivious transfer as long as the quantum bit-error rate of the channel does not exceed 11% and the noise on the channel is strictly less than the quantum storage noise. This is optimal for the protocol considered. Finally, we show that our analysis easily carries over to quantum protocols for secure identification.Comment: 34 pages, 2 figures. v2: clarified novelty of results, improved security analysis using fidelity-based smooth min-entropy, v3: typos and additivity proof in appendix correcte

State of the art of pricing policy in air transportation: network carriers vs. low-cost airlines

The modern air transport industry is highly competitive. To survive in the market, the implementation of a successful marketing strategy is fundamental. In particular, an effective pricing policy has become crucial for airlines to remain profitable. Correspondingly, the different types of airline in the market have also established very distinct pricing policies. The present study is based on a literature review and presents the state of the art of pricing policy in air transportation. The aim is to compare and discuss the pricing strategies of network carriers and low-cost airlines. Special attention is paid to Revenue Management, which is a very important management tool used by airlines to take advantage of the differences in willingness to pay of passengers. The pricing policy, however, depends on the overall business strategy of the airline. Results show many differences, resulting from the fact that these two types of airline are characterized by very different fundamental business models and, correspondingly, also target groups. Since network carriers and also low-cost airlines have adjusted their pricing strategies lately, these recent developments will be discussed as well. This paper adds to the knowledge of this topic because it presents the most up-to-date and complete study on pricing regarding network carriers vs. low-cost airlines.A moderna indústria do transporte aéreo é altamente competitiva. Para sobreviver no mercado, a implementação de uma estratégia de marketing bem-sucedida é fundamental. Em particular, uma política de preços eficaz tornou-se crucial para as companhias aéreas continuarem lucrativas. Os diferentes tipos de companhias aéreas no mercado também estabeleceram políticas de preços muito distintas. O presente estudo baseia-se numa revisão da literatura e apresenta o estado da arte da política de preços no transporte aéreo. O objetivo é comparar e discutir as estratégias de preços de companhias aéreas de linha e companhias aéreas de baixo custo. Atenção especial é dada à Gestão de Receitas (Revenue Management), que é uma ferramenta de gestão usada pelas companhias aéreas para aproveitar as diferenças na disposição de pagar dos passageiros. A política de preços, no entanto, depende da estratégia geral de negócios da companhia aérea. Os resultados mostram muitas diferenças, resultantes do facto de que esses dois tipos de companhias aéreas são caracterizados por modelos de negócios fundamentais muito diferentes e, correspondentemente, também grupos-alvo. Como as operadoras de rede e também as companhias aéreas de baixo custo ajustaram as suas estratégias de preços ultimamente, esses desenvolvimentos recentes também serão discutidos. Este documento contribui para o conhecimento deste tópico, pois apresenta o estudo mais atualizado e completo sobre preços de companhias aéreas de linha versus companhias aéreas de baixo custo.info:eu-repo/semantics/publishedVersio

Experimental implementation of bit commitment in the noisy-storage model

Fundamental primitives such as bit commitment and oblivious transfer serve as building blocks for many other two-party protocols. Hence, the secure implementation of such primitives are important in modern cryptography. In this work, we present a bit commitment protocol which is secure as long as the attacker's quantum memory device is imperfect. The latter assumption is known as the noisy-storage model. We experimentally executed this protocol by performing measurements on polarization-entangled photon pairs. Our work includes a full security analysis, accounting for all experimental error rates and finite size effects. This demonstrates the feasibility of two-party protocols in this model using real-world quantum devices. Finally, we provide a general analysis of our bit commitment protocol for a range of experimental parameters.Comment: 21 pages (7 main text +14 appendix), 6+3 figures. New version changed author's name from Huei Ying Nelly Ng to Nelly Huei Ying Ng, for consistency with other publication

El sector del transporte aéreo en España y Alemania: Un estudio comparativo de factores determinantes de la lealtad del pasajero

La creciente competencia durante los últimos años ha convertido el sector del transporte aéreo en un ámbito empresarial complejo. Por ello, no sorprende que muchas compañías aéreas hayan empezado a sufrir resultados adversos. Para sobrevivir en este mercado tan competitivo, una estrategia orientada al consumidor es de gran importancia para las compañías aéreas. Sin embargo, esto supone un desafío especial, puesto que las compañías aéreas suelen operar a nivel internacional y, por lo tanto, se enfrentan a una demanda de transporte aéreo muy diversa. Dentro de sus estrategias de marketing internacional, las aerolíneas tienen que decidir si se adaptan a las distintas necesidades y expectativas de los consumidores de los mercados locales. Mientras que ignorar completamente estas diferencias ofreciendo un servicio estandarizado permite ahorrar muchos costes, un servicio muy diferenciado garantiza cumplir las necesidades de los consumidores, a unos costes más elevados. Las compañías aéreas tienen que determinar para cada país en el que operan, el equilibrio óptimo entre estandarización y diferenciación. Aparte de la importancia del mercado, las decisiones estratégicas en este contexto dependen, sobre todo, de la orientación estratégica general de la compañía aérea, es decir, liderazgo en costes o de diferenciación, así como de las características de los públicos objetivos en el país. El objetivo principal de la presente tesis doctoral es analizar y comparar los pasajeros españoles y alemanes para descubrir posibles diferencias entre ellos, que podrían ser de relevancia para las estrategias de marketing internacional de las aerolíneas que operan en estos países. El análisis se basa en una encuesta realizada a través de un cuestionario, en el que los pasajeros españoles y alemanes han tenido que responder a una serie de cuestiones relacionadas con su último vuelo con respecto a la calidad de servicio percibida, el valor percibido, la satisfacción, y sus intenciones de lealtad hacia la compañía aérea. La encuesta se ha realizado de forma online, así como también personalmente en las cercanías de dos aeropuertos españoles. En total, se han recogido 742 cuestionarios válidos de pasajeros españoles y 781 de pasajeros alemanes. Aparte de un análisis descriptivo de los datos, se comparan las relaciones entre los constructos incluidos de marketing de los pasajeros españoles y alemanes. Como existen aerolíneas con modelos de negocio muy distintos en el mercado, se incluyen diferentes niveles de análisis en la presente tesis doctoral. Los dos tipos decompañías aéreas más importantes son las aerolíneas tradicionales (también conocidas como compañías aéreas de red) y las aerolíneas de bajo coste. Las aerolíneas tradicionales se centran en ofrecer un servicio de alta calidad, mientras que las aerolíneas de bajo coste se caracterizan por proveer el transporte aéreo con un número reducido de servicios incluidos, pero a un precio muy económico. Debido a las estrategias de negocios opuestas que tienen estos dos tipos de compañías aéreas, las características de sus públicos objetivos son también muy distintas. Por lo tanto, además de una comparación de los viajeros españoles y alemanes incluyendo a los pasajeros de todas las aerolíneas, también se comparan ambas nacionalidades teniendo en consideración de manera separada los pasajeros de compañías aéreas de red y los viajeros de aerolíneas de bajo coste. Los resultados del estudio empírico han descubierto varias similitudes, pero también algunas diferencias entre pasajeros españoles y alemanes. Los hallazgos indican que la satisfacción del consumidor es el factor clave para garantizar la lealtad de los pasajeros hacia una compañía aérea. No obstante, se han encontrado diferencias en cuanto a la formación de la satisfacción de los clientes. Para los pasajeros alemanes, la satisfacción depende principalmente de la calidad de servicio percibida. En cambio, para los viajeros españoles, también, el valor percibido es de gran relevancia en la formación de la satisfacción. Con respecto a los pasajeros de los distintos tipos de compañía aérea, se puede apreciar que los viajeros españoles y alemanes que vuelan con aerolíneas de bajo coste parecen que son muy similares en referencia al comportamiento del consumidor. Sin embargo, sucede el caso inverso con respecto a los pasajeros de compañías aéreas de red. Los resultados tienen implicaciones prácticas para las aerolíneas que operan en los dos países analizados.The continuously increasing competition over the last years turned the air transport sector in a very complex business environment. Therefore, it is not surprising that many airlines are currently struggling with declining profits. In order to survive in this highly competitive market, a customer-oriented marketing strategy is of paramount importance for airlines. However, this has been found to be challenging, since airlines usually operate at an international level and, consequently, face a very diverse demand for air travel. Within their international marketing strategies, airlines have to decide whether or not they adapt to the different needs and expectations of local market customers. Whereas completely ignoring the differences by offering a standardized service leads to significant cost savings, a highly differentiated service guarantees to meet customer needs, it is, however, very cost-intensive. An airline has to determine the optimum balance between standardization and differentiation for each country in which it is operating. Besides the importance of the market in question, strategic decisions in this context depend, especially, on the overall strategic orientation of the airline, i.e. cost leadership or differentiation strategy, as well as the characteristics of the target groups in the country. The main objective of the present dissertation is to analyze and compare Spanish and German airline passengers in order to reveal possible differences among them, which could ultimately be useful for the international marketing strategies for airlines operating in these countries. The analysis is based on a survey conducted by way of a questionnaire, in which Spanish and German passengers were asked several questions related to their last flight with regard to perceived service quality, perceived value, satisfaction and their loyalty intentions towards the airline. The survey was carried out online as well as in person in the vicinity of two Spanish airports. In total, 742 valid questionnaires from Spanish passengers and 781 from German passengers were collected. Besides a descriptive data analysis of the assessments of the flights, the relationships between the included marketing constructs are tested and compared between Spanish and German passengers. Since airlines with very distinctive business models are established on the market, different levels of analysis are included in the present dissertation. The two most important airline types are legacy carriers (also called network carriers) and low-cost airlines. Whereas legacy carriers focus on offering a high-quality service, low-cost carriers are characterized by providing air transportation with a very reduced number of services included, but at a very low price. Because of these contrasting business strategies, the characteristics of the target groups of the two mentioned airline types are very different as well. Therefore, apart from a comparison of Spanish and German travellers including passengers of all airlines, both nationalities are also compared considering separately passengers of network carriers as well as passengers of low-cost carriers. The empirical study revealed several similarities, but also some differences between Spanish and German passengers. The results indicate that in both nationalities, satisfaction is thecrucial factor to guarantee loyalty of the passengers towards an airline. However, differences can be found regarding the formation of customer satisfaction. For German passengers, the satisfaction mainly depends on the perceived service quality. On the other hand, for Spanish passengers, in addition, the perceived value is of high relevance in the formation of satisfaction. Concerning the passengers of the individual airline types, it can be noted that the Spanish and German travellers flying with low-cost carriers seem to be very similar with regard to consumer behaviour. However, with respect to the passengers of network carriers, the opposite occurs. The findings of the empirical study have practical implications for airlines operating in the two analyzed countries

Bibliometrie in der Forschungsevaluation. Zur Konstitution und Funktionslogik wechselseitiger Beobachtung zwischen Wissenschaft und Politik

Taubert NC. Bibliometrie in der Forschungsevaluation. Zur Konstitution und Funktionslogik wechselseitiger Beobachtung zwischen Wissenschaft und Politik. In: Passoth J, Wehner J, eds. Quoten, Kurven und Profile. Zur Vermessung der sozialen Welt. Wiesbaden: Springer VS; 2013: 179-204

Untersuchung der Schallimmission im Zentrum von Leipzig

Negativ empfundene Schallereignisse, d.h. Lärm, sind nach wie vor eines der bedeutendsten Umweltprobleme besonders in urbanen Räumen. Die Ausbreitung von Schallwellen findet, abgesehen von Wechselwirkungen mit dem Boden, in der Atmosphäre statt und wird durch deren Struktur beeinflusst. Eine maßgebliche Rolle spielt dabei die raum-zeitliche Variabilität der meteorologischen Größen Temperatur, Windvektor sowie Luftfeuchtigkeit, die durch Brechung, Streuung und Absorption zu einer verstärkten oder verringerten Schallimmission an einem Ort führen kann. Im Rahmen einer Schülerarbeit (“Besondere Lernleistung”) wurden Schallpegelwerte an mehreren Messpunkten auf dem Gelände des Leipziger Instituts für Meteorologie bei verschiedenen Atmosphärenzuständen aufgenommen. Erste Auswertungen der Messergebnisse werden in dieser Studie vorgestellt.Noise is one of the most important environmental problems especially in urban regions. The propagation of sound waves takes place in the atmosphere, apart from interactions with the ground surface, and is influenced by the atmospheric structure. Thereby, the spatial and temporal variability of meteorological quantities like temperature, wind vector and air moisture leads to refraction, scattering and absorption and thereupon to an increased or decreased noise exposure. Within the scope of a pupil’s work sound level measurements were carried out on different places at the site of Leipzig Institute of Meteorology during variable atmospheric conditions. First results are presented in this study

Immune response of hibernating European bats to a fungal challenge

Immunological responses of hibernating mammals are suppressed at low body temperatures, a possible explanation for the devastating effect of the white-nose syndrome on hibernating North American bats. However, European bats seem to cope well with the fungal causative agent of the disease. To better understand the immune response of hibernating bats, especially against fungal pathogens, we challenged European greater mouse-eared bats (Myotis myotis) by inoculating the fungal antigen zymosan. We monitored torpor patterns, immune gene expressions, different aspects of the acute phase response and plasma oxidative status markers, and compared them with sham-injected control animals at 30 min, 48 h and 96 h after inoculation. Torpor patterns, body temperatures, body masses, white blood cell counts, expression of immune genes, reactive oxygen metabolites and non-enzymatic antioxidant capacity did not differ between groups during the experiment. However, zymosan injected bats had significantly higher levels of haptoglobin than the control animals. Our results indicate that hibernating greater mouse-eared bats mount an inflammatory response to a fungal challenge, with only mild to negligible consequences for the energy budget of hibernation. Our study gives a first hint that hibernating European bats may have evolved a hibernation-adjusted immune response in order to balance the trade-off between competent pathogen elimination and a prudent energy-saving regime

CAMP: An instrumented platform for balloon-borne aerosol particle studies in the lower atmosphere

Airborne observations of vertical aerosol particle distributions are crucial for detailed process studies and model improvements. Tethered balloon systems represent a less expensive alternative to aircraft to probe shallow atmospheric boundary layers (ABLs). This study presents the newly developed cubic aerosol measurement platform (CAMP) for balloon-borne observations of aerosol particle microphysical properties. With an edge length of 35 cm and a weight of 9 kg, the cube is an environmentally robust instrument platform intended for measurements at low temperatures, with a particular focus on applications in cloudy Arctic ABLs. The aerosol instrumentation on board CAMP comprises two condensation particle counters with different lower detection limits, one optical particle size spectrometer, and a miniaturized absorption photometer. Comprehensive calibrations and characterizations of the instruments were performed in laboratory experiments. The first field study with a tethered balloon system took place at the Leibniz Institute for Tropospheric Research (TROPOS) station in Melpitz, Germany, in the winter of 2019. At ambient temperatures between-8 and 15 C, the platform was operated up to a 1.5 km height on 14 flights under both clear-sky and cloudy conditions. The continuous aerosol observations at the ground station served as a reference for evaluating the CAMP measurements. Exemplary profiles are discussed to elucidate the performance of the system and possible process studies. Based on the laboratory instrument characterizations and the observations during the field campaign, CAMP demonstrated the capability to provide comprehensive aerosol particle measurements in cold and cloudy ABLs

Crucial role of ultraviolet light for desert ants in determining direction from the terrestrial panorama

Ants use the panoramic skyline in part to determine a direction of travel. A theoretically elegant way to define where terrestrial objects meet the sky is to use an opponent-process channel contrasting green wavelengths of light with ultraviolet (UV) wavelengths. Compared with the sky, terrestrial objects reflect relatively more green wavelengths. Using such an opponent-process channel gains constancy in the face of changes in overall illumination level. We tested the use of UV wavelengths in desert ants by using a plastic that filtered out most of the energy below 400 nm. Ants, Melophorus bagoti, were trained to home with an artificial skyline provided by an arena (experiment 1) or with the natural panorama (experiment 2). On a test, a homing ant was captured just before she entered her nest, and then brought back to a replicate arena (experiment 1) or the starting point (the feeder, experiment 2) and released. Blocking UV light led to deteriorations in orientation in both experiments. When the artificial skyline was changed from opaque to transparent UV-blocking plastic (experiment 3) on the other hand, the ants were still oriented. We conclude that UV wavelengths play a crucial role in determining direction based on the terrestrial surround.10 page(s