On the Key-Uncertainty of Quantum Ciphers and the Computational Security of One-way Quantum Transmission

We consider the scenario where Alice wants to send a secret (classical) $n$-bit message to Bob using a classical key, and where only one-way transmission from Alice to Bob is possible. In this case, quantum communication cannot help to obtain perfect secrecy with key length smaller then $n$. We study the question of whether there might still be fundamental differences between the case where quantum as opposed to classical communication is used. In this direction, we show that there exist ciphers with perfect security producing quantum ciphertext where, even if an adversary knows the plaintext and applies an optimal measurement on the ciphertext, his Shannon uncertainty about the key used is almost maximal. This is in contrast to the classical case where the adversary always learns $n$ bits of information on the key in a known plaintext attack. We also show that there is a limit to how different the classical and quantum cases can be: the most probable key, given matching plain- and ciphertexts, has the same probability in both the quantum and the classical cases. We suggest an application of our results in the case where only a short secret key is available and the message is much longer.Comment: 19 pages, 2 figures. This is a revised version of an earlier version that appeared in the proc. of Eucrocrypt'04:LNCS3027, 200

A logic approach for exceptions and anomalies in association rules

Association rules have been used for obtaining information hidden in a database. Recent researches have pointed out that simple associations are insu cient for representing the diverse kinds of knowledge collected in a database. The use of exceptions and anomalies deal with a di erent type of knowledge sometimes more useful than simple associations. Moreover ex- ceptions and anomalies provide a more comprehensive understanding of the information provided by a database. This work intends to go deeper in the logic model studied in [5]. In the model, association rules can be viewed as general relations between two or more attributes quanti ed by means of a convenient quanti er. Using this formulation we establish the true semantics of the distinct kinds of knowledge we can nd in the database hidden in the four folds of the contingency table. The model is also useful for providing some measures for assessing the validity of those kinds of rulesPeer Reviewe

Effects of historical land-use change in the Mediterranean environment

During the Holocene (last ~11,700 years), societies have continuously modified the landscape of the Mediterranean Basin through changes in land-use, exerting extraordinary pressures onto the environment and adding variability to the climate. Despite its importance to current land management, knowledge of how past land-use practices have impacted the regional climate of the Basin remains largely in the scientific sphere. Thereby, this work aims to inform non-scientific actors and practitioners about the environmental effects of past land-use changes on the hydrologic cycle of the Mediterranean Basin. For this purpose we: i) summarize fundamental observed interactions between land-use change and the environment, identified through a semi-systematic review of 23 scientific case-studies from around the Basin; ii) reflect on the consequences to the Mediterranean environment (atmosphere, biosphere, lithosphere, and hydrosphere) in a synthesized and integrated way; iii) argue the need for taking into account the impact of local land-use practices from a regional-scale perspective; iv) highlight the importance of recognizing historical factors, such as past land-use changes, for developing protective strategies in the rural areas of the Basin. With this work, we provide a synthesized and more integrated understanding of the effects of past and local land-use changes in the regional Mediterranean environment, assisting to bridge the gap between scientific findings, Mediterranean watersheds stakeholders, and regional policy-makers. © 2020The authors would like to thank David Moreno (BC3) for his valuable reflections when developing the manuscript, Erik-Logan Hughes (MIT) for his help constructing the feedback network map, Ambika Markanday (BC3) for her language revisions, and three anonymous reviewers that improved this work with their constructive comments. This research is supported by the Basque Government through the BERC 2018-2021 program and by the Spanish Ministry of Economy and Competitiveness MINECO through BC3 María de Maeztu excellence accreditation MDM 2017-0714

Influence of Zn excess on compositional, structural and vibrational properties of Cu2ZnSn0.5Ge0.5Se4 thin films and their effect on solar cell efficiency

This Accepted Manuscript will be available for reuse under a CC BY-NC-ND licence after 24 months of embargo periodThe effect of Zn content on compositional, structural and vibrational properties of Cu2ZnSn1-xGexSe4 (CZTGSe, x ~ 0.5) thin films is studied. Kesterite layer is deposited by co-evaporation onto 5 × 5 cm2 Mo/SLG substrate followed by a thermal treatment at maximum temperature of 480 °C, obtaining areas with different composition and morphology which are due to the sample position in the co-evaporation system and to the non-uniform temperature distribution across the substrate. Kesterite layers with higher Zn amounts are characterized by lower Cu and Ge contents; however, a uniform Ge distribution through the absorber layer is detected in all cases. The excess Zn concentration leads to the formation of ZnSe secondary phase on the surface and in the bulk of the absorber as determined by Raman spectroscopy. When higher Ge content and no ZnSe are present in the absorber layer, a compact structure is formed with larger grain size of kesterite. This effect could explain the higher Voc of the solar cell. The Zn content does not affect the bandgap energy significantly (Eg near 1.3 eV), although the observed effect of Zn excess in CZTGSe results in a decreased device performance from 6.4 to 4.2%. This investigation reveals the importance of the control of the off-stoichiometric CZTGSe composition during the deposition process to enhance solar cells propertiesThis work was supported by Spanish Ministry of Science, Innovation and Universities Project WINCOST (ENE2016-80788-C5-2-R) and European Project INFINITE CELL (H2020-MSCA-RISE-2017-777968). ARP also acknowledges financial support from Community of Madrid within Youth Employment Program (PEJD-2017-PRE/IND-4062). MG acknowledges the financial support from ACCIÓ-Generalitat de Catalunya within the TECNIOspring Plus fellowship (TECSPR18-1-0048

Recent flowering of Posidonia oceanica (L.) Delile at the SE of the Iberian peninsula

Floraciones de Posidonia en dos localidades del Mediterráneo estimadas por lepidocronología

Resolution of First- and Second-Order Linear Differential Equations with Periodic Inputs by a Computer Algebra System

In signal processing, a pulse means a rapid change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value. A square wave function may be viewed as a pulse that repeats its occurrence periodically but the return to the baseline value takes some time to happen. When these periodic functions act as inputs in dynamic systems, the standard tool commonly used to solve the associated initial value problem (IVP) is Laplace transform and its inverse. We show how a computer algebra system may also provide the solution of these IVP straight forwardly by adequately introducing the periodic input

The moderating role of gender on entrepreneurial intentions: a TPB perspective

Purpose: To disentangle the ways in which social norms shape entrepreneurial intentions of university students and to analyse the moderating effect of gender that may arise. Design/methodology/approach: We have used the entrepreneurial intention model based on Theory of Planned Behaviour (TPB) literature and moderated by students’ gender affecting this intention. We tested some hypotheses using data from undergraduate business students in Spain and their entrepreneurial intentions. Findings: Our results suggest that perceived behavioural control and attitudes affect the entrepreneurial intentions of university students towards entrepreneurship while subjective norms do not. Furthermore, our findings reveal that the moderating effect of gender has a positive influence for women in the relationship between those subjective norms and the perceived behavioural control. However, as to some research done so far, the moderating role of gender does not seem to have a particular effect on predicting entrepreneurial intentions when moderating TPB dimensions. Practical implications: Given the socio-economic benefits attributed to entrepreneurship, the results allow the design of more effective education initiatives and policies. Originality/value: This research provides support for the application of the TPB, allowing for a better understanding of gender differences in entrepreneurial intentions