How to distinguish between a block cipher and a random permutation by lowering the input entropy

IEEE 35th International Carnahan Conference on Security Technology. Londres, 16-19 October 2001A novel cryptanalysis technique is presented, and its suitability for distinguishing a block cipher algorithm or a hash function from a random permutation is explained. Additionally, we propose a genetic algorithm based implementation and show some preliminary results of these ideas on reduced rounds versions of the block cipher TEA

Using classifiers to predict linear feedback shift registers

Proceeding of: IEEE 35th International Carnahan Conference on Security Technology. October 16-19, 2001, LondonPreviously (J.C. Hernandez et al., 2000), some new ideas that justify the use of artificial intelligence techniques in cryptanalysis are presented. The main objective of that paper was to show that the theoretical next bit prediction problem can be transformed into a classification problem, and this classification problem could be solved with the aid of some AI algorithms. In particular, they showed how a well-known classifier called c4.5 could predict the next bit generated by a linear feedback shift register (LFSR, a widely used model of pseudorandom number generator) very efficiently and, most importantly, without any previous knowledge over the model used. The authors look for other classifiers, apart from c4.5, that could be useful in the prediction of LFSRs. We conclude that the selection of c4.5 by Hernandez et al. was adequate, because it shows the best accuracy of all the classifiers tested. However, we have found other classifiers that produce interesting results, and we suggest that these algorithms must be taken into account in the future when trying to predict more complex LFSR-based models. Finally, we show some other properties that make the c4.5 algorithm the best choice for this particular cryptanalytic problem.Publicad

Enabling conditions for the implementation and conservation outcomes of a private nature reserve

Expanding conservation efforts to private land is paramount to halt biodiversity loss and achieve global conservation targets. Individual landowners can play disproportionately important roles by establishing private parks and managing them with biodiversity‐focused objectives. However, several constraints hinder the expansion of such initiatives, and little is known about their extent, characteristics and keys for success.Here, we provide insights on the conditions that favoured the establishment and conservation outcomes of a private reserve in central Spain whose management has been fully conservation‐oriented for the past two decades. We report on the actions implemented to accomplish four key targets that aimed at protecting and enhancing wildlife populations, and on the landholder's motivations to devote his personal resources to pursue this goal.The landholder suggests that public policy should reduce the bureaucratic burden to intrinsically motivated landowners and provide them technical advice, trust and financial incentives to expand conservation on private land.Ministerio de Asuntos Económicos y Transformación DigitalMinisterio de Ciencia e InnovaciónMinisterio de Educación, Cultura y DeporteComunidad de Madri

Calendario pluviométrico en el margen oriental del área agrícola argentina

En el margen oriental del área agrícola Argentina se combinan un régimen de precipitaciones abundantes, con frecuentes episodios de tormentas intensas, con suelos pesados de tipo vertisol, lo cual dificulta considerablemente el desarrollo de las labores agrícolas. En dicho ambiente reviste gran importancia contar con calendarios pluviométricos que permitan planificar las tareas agropecuarias. Con esta finalidad, se analizaron los datos diarios de precipitación de cuatro localidades de la Provincia de Entre Ríos, cuyos registros son representativos de lo expuesto, a fin de evaluar la existencia de fechas con probabilidad significativa de que no ocurran precipitaciones y fechas con alta probabilidad de ocurrencia de precipitaciones y alta intensidad de las mismas. Los resultados obtenidos se cotejaron con las fechas de siembra y cosecha de los cultivos más comunes en la zona a fin de determinar las implicancias de los resultados alcanzados. El análisis de los datos demostró que efectivamente hay días del año definidos como días secos, con probabilidad diaria de precipitación menor al 10 % y con cantidad media diaria de precipitación menor a 1 mm, concentrados mayormente en los meses que van de mayo a septiembre; y días de tormenta con probabilidad diaria de precipitación mayor al 20 % y con cantidad media diaria de precipitación mayor a 25 mm, distribuidos a lo largo de todo el año, pero con singularidades en otoño y primavera.The eastern margin of the argentinian agricultural area combines a regime of plentiful precipitations, with frequent heavy storms, with heavy vertisolic soils, which considerably hampers fieldwork. In this environment is very important to develop pluviometric calendars which may allow to plan the agricultural activities. With this aim, data from 4 localizations in Entre Ríos Province, Argentina, were analyzed to assess the existence of dates with significant probability of precipitation or no precipitation. The results obtained were compared with the dates of planting, bloom and harvest of more common crops in the zone to determinate the implications of the reached results. This analysis showed the effective existence of dry days, with a precipitation probability less than 10% and a daily mean under 1 mm, concentrated mainly in the months from May to September, as well as stormy days, with a precipitation probability higher than 20% and a daily mean over 25 mm, distributed all over the year, but with some preference for spring and autumn.Fil: Perez, Silvia P.. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Recursos Naturales y Ambiente. Cátedra de Climatología y Fenologias Agrícolas; ArgentinaFil: Sierra, Eduardo Mario. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Recursos Naturales y Ambiente. Cátedra de Climatología y Fenologias Agrícolas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; ArgentinaFil: Peschiera, José M.. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Recursos Naturales y Ambiente. Cátedra de Climatología y Fenologias Agrícolas; Argentin

Estudio de las redes educativas de centros escolares en Andalucía (España): claves para su análisis de la evaluación de los asesores de centros de profesores

Every school constitutes a singular case when it comes to changes and improvements as each of them belongs to a social and cultural context with their own idiosyncrasy and needs. This article aims to study 12 in depth a research on educative networks organized in groups of teachers, focusing on its origin, structure, resources, organization and impact. The process of data gathering has followed a descriptivenarrative methodology, based on a qualitative research, and using a questionnaire for advisors in Teachers Centers within Seville, where they inform about the benefits of networking. The results of the analysis show that the development and setting of these networks occur in response to both the need of support that teachers are sometimes missing in their professional day to day; and the requirements of the regional inspection service of education, Servicio de Inspección Educativa, in order to cope with basic difficulties that may arise in the teaching learning process, such as the reading and writing learning process or the improvement of the coexistence within the educational community. Feedback from this research proves the impact that the networking procedures have had in the educational community and centers, as well as its positive results and improvements in their development.Cada escuela se constituye en un caso especial para la implementación de cambios y mejoras, de forma que cada una responde a un contexto social y cultural con su propia idiosincrasia y necesidades. El objetivo principal del artículo es dar a conocer el estudio de las redes educativas configuradas en grupos de trabajo entre profesores en lo que se refiere a su origen, diseño, recursos, organización e impacto, con la finalidad de profundizar en su funcionamiento y repercusión en los centros escolares. Para la recogida de datos se ha utilizado una metodología descriptivo narrativa, basada en la investigación cualitativa, a partir de un cuestionario para asesores de centros de profesores de Sevilla capital y provincia, donde informan de la idoneidad del trabajo en red. Los resultados del análisis determinan que el desarrollo y puesta en marcha de las redes responde a las necesidades de apoyo que los docentes encuentran en su desarrollo profesional y a la exigencia del Servicio de Inspección Educativa para paliar problemas básicos dentro del proceso de enseñanza aprendizaje, como es el aprendizaje de la lectoescritura y la mejora de la convivencia en la comunidad educativa. Las principales conclusiones reconocen el impacto del trabajo en red en los centros y en la comunidad educativa, sus resultados y las mejoras en el desarrollo de las mismas

Robust new method in frequency domain watermarking

Proceeding of: 4th International Conference, ISC 2001, Malaga, Spain, October 1-3, 2001This article presents a new and robust watermarking method in the frequency domain that improves over the existing ones. It is robust to JPEG compression, very configurable, simple, efficient and very easy to implement. Apart from JPEG test, it shows very good results in all tests applied.Publicad

Internal ribosome entry site drives cap-independent translation of reaper and heat shock protein 70 mRNAs in Drosophila embryos

Translation is a sensitive regulatory step during cellular stress and the apoptosis response. Under such conditions, cap-dependent translation is reduced and internal ribosome entry site (IRES)-dependent translation plays a major role. However, many aspects of how mRNAs are translated under stress remain to be elucidated. Here we report that reaper mRNA, a pro-apoptotic gene from Drosophila melanogaster, is translated in a cap-independent manner. In Drosophila mutant embryos devoid of the eukaryotic initiation factor 4E (eIF4E), reaper transcription is induced and apoptosis proceeds. In vitro translation experiments using wild-type and eIF4E mutant embryonic extracts show that reporter mRNA bearing reaper 5′ untranslated region (UTR) is effectively translated in a cap-independent manner. The 5′UTR of reaper exhibits a high degree of similarity with that of Drosophila heat shock protein 70 mRNA, and both display IRES activity. Studies of mRNA association to polysomes in embryos indicate that both reaper and heat shock protein 70 70 mRNAs are recruited to polysomes under apoptosis or thermal stress. Our data suggest that heat shock protein 70 70 and reaper, two antagonizing factors in apoptosis, use a similar mechanism for protein synthesis.Facultad de Ciencias Exacta

Printers are dangerous

Proceeding of: IEEE 35th International Carnahan Conference on Security Technology, London , UK, 16 - 19 october 2001In the last years, many new intelligent full-featured peripherals that assist information systems have appeared. Those peripherals, such as printers, copiers, PDA organizers, Web cameras, etc. usually have a very friendly way of configuration and management (via http, ftp or telnet servers) and offer more networked services everyday. Their computation, memory and networking capabilities have also increased in the last years. Nowadays, many of them are comparable to workstations and run complete operating systems such as Linux or Solaris. All those factors imply that these devices could represent a real threat to the security of information systems. This problem is even worse because most of those peripherals have been considered inoffensive and not many administrators are aware of their security risks. The most representative example is printers, which have been traditionally considered totally harmless devices. At the present time, that idea is difficult to defend because many security incidents related with networked printers have arisen in the last years. System and security administrators have traditionally focused their efforts in fortifying servers and hosts only, but it seems that this view is not enough for assuring security nowadays.Publicad

The hydrosoluble fiber Plantago ovata husk improves levodopa (with carbidopa) bioavailability after repeated administration

P. 15-20The influence of treatment duration (7 or 14 days) with Plantago ovata husk/levodopa/carbidopa in the bioavailability and other pharmacokinetic parameters of levodopa were evaluated in rabbits. Fiber was administered at two different doses, 100 and 400 mg/kg, and the dosage of levodopa/carbidopa was 20:5 mg/kg. These doses were administered once a day. When 100 mg/kg of fiber was administered, the mean AUC value obtained for levodopa increased 20.2% from day 1 to day 7, and 27.2% from day 1 to day 14; Cmax was 8.6% higher on day 7 and 11.7% higher on day 14. When administering 400 mg/kg of fiber, the increase in AUC values was 17.6% on day 7 and 24.9% on day 14, and that of Cmax 11.1% on day 7 and 11.3% on day 14. The concentration determined immediately before drug administration (Cmin) increased progressively with the duration of treatment, and the highest increase (53.2%) was observed on day 14 with 100 mg/kg of fiber. There was also a delay in levodopa elimination (higher MRT and lower Cl) in a fiber-dose dependent manner. In summary, we found that there was an improvement in the extent of levodopa absorbed with higher final concentrations and that levodopa elimination was slower with the administration of P. ovata husk.S