The Ultraviolet Sky: An Overview from the GALEX Surveys

The Galaxy Evolution Explorer (GALEX) has performed the first surveys of the sky in the Ultraviolet (UV). Its legacy is an unprecedented database with more than 200 million source measurements in far-UV (FUV) and near-UV (NUV), as well as wide-field imaging of extended objects, filling an important gap in our view of the sky across the electromagnetic spectrum. The UV surveys offer unique sensitivity for identifying and studying selected classes of astrophysical objects, both stellar and extra-galactic. We examine the overall content and distribution of UV sources over the sky, and with magnitude and color. For this purpose, we have constructed final catalogs of UV sources with homogeneous quality, eliminating duplicate measurements of the same source. Such catalogs can facilitate a variety of investigations on UV-selected samples, as well as planning of observations with future missions. We describe the criteria used to build the catalogs, their coverage and completeness. We included observations in which both the far-UV and near-UV detectors were exposed; 28,707 fields from the All-Sky Imaging survey (AIS) cover a unique area of 22,080 square degrees (after we restrict the catalogs to the central 1-degree diameter of the field), with a typical depth of about 20/21 mag (FUV/NUV, in the AB mag system), and 3,008 fields from the Medium-depth Imaging Survey (MIS) cover a total of 2,251 square degrees at a depth of about 22.7mag. The catalogs contain about 71 and 16.6 million sources respectively. The density of hot stars reflects the Galactic structure, and the number counts of both Galactic and extra-galactic sources are modulated by the Milky Way dust extinction, to which the UV data are very sensitive.Comment: J. Adv. Space Res. (2013), Full resolution figures can be found in the original published article (open access) at : http://www.sciencedirect.com/science/article/pii/S0273117713004742 or from http://dolomiti.pha.jhu.edu/publgoto.html ; catalogs are posted on MAS

To NACK or not to NACK? Negative Acknowledgments in Information-Centric Networking

Information-Centric Networking (ICN) is an internetworking paradigm that offers an alternative to the current IP\nobreakdash-based Internet architecture. ICN's most distinguishing feature is its emphasis on information (content) instead of communication endpoints. One important open issue in ICN is whether negative acknowledgments (NACKs) at the network layer are useful for notifying downstream nodes about forwarding failures, or requests for incorrect or non-existent information. In benign settings, NACKs are beneficial for ICN architectures, such as CCNx and NDN, since they flush state in routers and notify consumers. In terms of security, NACKs seem useful as they can help mitigating so-called Interest Flooding attacks. However, as we show in this paper, network-layer NACKs also have some unpleasant security implications. We consider several types of NACKs and discuss their security design requirements and implications. We also demonstrate that providing secure NACKs triggers the threat of producer-bound flooding attacks. Although we discuss some potential countermeasures to these attacks, the main conclusion of this paper is that network-layer NACKs are best avoided, at least for security reasons.Comment: 10 pages, 7 figure

Poseidon: Mitigating Interest Flooding DDoS Attacks in Named Data Networking

Content-Centric Networking (CCN) is an emerging networking paradigm being considered as a possible replacement for the current IP-based host-centric Internet infrastructure. In CCN, named content becomes a first-class entity. CCN focuses on content distribution, which dominates current Internet traffic and is arguably not well served by IP. Named-Data Networking (NDN) is an example of CCN. NDN is also an active research project under the NSF Future Internet Architectures (FIA) program. FIA emphasizes security and privacy from the outset and by design. To be a viable Internet architecture, NDN must be resilient against current and emerging threats. This paper focuses on distributed denial-of-service (DDoS) attacks; in particular we address interest flooding, an attack that exploits key architectural features of NDN. We show that an adversary with limited resources can implement such attack, having a significant impact on network performance. We then introduce Poseidon: a framework for detecting and mitigating interest flooding attacks. Finally, we report on results of extensive simulations assessing proposed countermeasure.Comment: The IEEE Conference on Local Computer Networks (LCN 2013

The Dark Side(-Channel) of Mobile Devices: A Survey on Network Traffic Analysis

In recent years, mobile devices (e.g., smartphones and tablets) have met an increasing commercial success and have become a fundamental element of the everyday life for billions of people all around the world. Mobile devices are used not only for traditional communication activities (e.g., voice calls and messages) but also for more advanced tasks made possible by an enormous amount of multi-purpose applications (e.g., finance, gaming, and shopping). As a result, those devices generate a significant network traffic (a consistent part of the overall Internet traffic). For this reason, the research community has been investigating security and privacy issues that are related to the network traffic generated by mobile devices, which could be analyzed to obtain information useful for a variety of goals (ranging from device security and network optimization, to fine-grained user profiling). In this paper, we review the works that contributed to the state of the art of network traffic analysis targeting mobile devices. In particular, we present a systematic classification of the works in the literature according to three criteria: (i) the goal of the analysis; (ii) the point where the network traffic is captured; and (iii) the targeted mobile platforms. In this survey, we consider points of capturing such as Wi-Fi Access Points, software simulation, and inside real mobile devices or emulators. For the surveyed works, we review and compare analysis techniques, validation methods, and achieved results. We also discuss possible countermeasures, challenges and possible directions for future research on mobile traffic analysis and other emerging domains (e.g., Internet of Things). We believe our survey will be a reference work for researchers and practitioners in this research field.Comment: 55 page

X and Y waves in the spatiotemporal Kerr dynamics of a self-guided light beam

The nonlinear stage of development of the spatiotemporal instability of the monochromatic Townes beam in a medium with self-focusing nonlinearity and normal dispersion is studied by analytical and numerical means. Small perturbations to the self-guided light beam are found to grow into two giant, splitting Y pulses featuring shock fronts on opposite sides. Each shocking pulse amplifies a co-propagating X wave, or dispersion- and diffraction-free linear wave mode of the medium, with super-broad spectrum.Comment: 9 pages, 9 figure

Full integration of teaching 'Medical Humanities' in the medical curriculum: the challenge of the florence medical school.

Mankind has always longed to preserve and improve health. However, inherent in the practice of medicine lies the possibility of danger. Overlying the problem is the role of the medical profession, the skills it proclaims to profess and its relationship with the patient. Members of the medical profession are often criticized for overriding the wishes of the patient or for acting without informed consent [1]. The role of informed consent is one of the great challenges to the ethics and practice of modern medicine. The aim of this letter is to point out how education in Medical Humanities can enhance physicians' education and facilitate a different approach towards the relationship with the patient. Medicine began by espousing a paternalistic attitude towards medical treatments, which were continued in spite of the patient's disapproval or ignorance. In recent times the concept of informed consent, based on information given to the patient regarding the means of treatment, its benefits and risks, has come to the fore. Very often, however, the patient may not clearly understand the situation, due to the inaccessibility of medical language to the great majority of the population. Furthermore, the great expansion of the Internet and of the media in general has produced an undesired effect: patients very often arrive in the outpatient clinic having already looked for alternative sources of information. This can place strains on the physicianpatient relationship since patients do not possess the medical knowledge needed to evaluate the quality of the information they have already obtained and doctors have difficulties in countering misinformation in their patients. Consequently, it is first necessary to clear away prejudices that can endanger the decision making process; thus physicians must spend more time in reaching increased patient involvement. However, a subjective approach is not enough to obtain the generalized satisfaction of patients: the establishment of a partnership between physician and patient is the winning choice, but it has to face the constant pressure of time. Time is therefore a fundamental key in facilitating the passage from compliance to concordance [2]. The other basic problem is that of language. Medical language has always been the expression of a closed social class: even the Hippocratic oath places emphasis on the fact that medical education is to be directed to the doctor's sons, the sons of his mentor and to the students who are going to swear the medical oath, but to nobody else. Not surprisingly, while other languages for special purposes have become institutionalized only in recent times, medical language was already shaped in the 13th century, confirming the ancient attitude of considering the medical class a privileged entity that acted as a repository of knowledge which could not be shared [3]. The in-depth study of the History of Medicine can be of aid in fully understanding current linguistic medical patterns and, most importantly, in avoiding the repetition of the errors of the past in the patient-physician relationship. A comprehensive awareness of medical ethics and professional deontology includes a correct attitude towards the patient, an attitude that begins from a clear and understandable language. With regard to this, recent deliberations on the medical profession have emphasized that the incorrect use of jargon has widened the distance between doctor and patient, creating a discontinuity between them, while, on the contrary, this distance should be bridged by the avoidance of ambiguous words, complicated expressions and complex concepts. To give some examples: the Salk vaccination for poliomyelitis has been abbreviated in so many ways that any reader may have difficulties in identifying them all; similarly, idiopathic myeloid splenomegaly has 12 synonyms in English, 13 in German and 31 in French [4]. The international classification of diseases, published by the World Health Organization, is ignored by the greater part of the medical community. It is also rejected by some medical schools, that follow their own local traditions of terminology. It is therefore necessary to put some order into medical language, to allow clarity of communication with the general public. Physicians must know how to speak with the patient and not to the patient and therefore they must abandon their jargon and their superior attitude. If their language is to be understood, it must be adapted to the specific needs of the patient. The doctor's code must correspond to that of the patient, particularly with respect to risks and benefits, and this can be the result only of a precise management of the relationship. How may these aims be reached? We think that Medical Humanities can play a fundamental role in the education of physicians. The History of Medicine, that has become a specific academic discipline in many European countries during the 20th century, has endowed itself with a triad of basic principles, which deal with its relevance in helping physicians to acquire clinical and epidemiological knowledge, its role in legitimatizing the rise of professional experts, and its function as a school of ethics, proposing a continuous reflection on the everyday profession and favouring the development of the exercise of criticism

On the estimation of the Lorenz curve under complex sampling designs

This paper focuses on the estimation of the concentration curve of a finite population, when data are collected according to a complex sampling design with different inclusion probabilities. A (design-based) Hajek type estimator for the Lorenz curve is proposed, and its asymptotic properties are studied. Then, a resampling scheme able to approximate the asymptotic law of the Lorenz curve estimator is constructed. Applications are given to the construction of (i) a confidence band for the Lorenz curve, (ii) confidence intervals for the Gini concentration ratio, and (iii) a test for Lorenz dominance. The merits of the proposed resampling procedure are evaluated through a simulation study