PDF-Malware Detection: A Survey and Taxonomy of Current Techniques

Portable Document Format, more commonly known as PDF, has become, in the last 20 years, a standard for document exchange and dissemination due its portable nature and widespread adoption. The flexibility and power of this format are not only leveraged by benign users, but from hackers as well who have been working to exploit various types of vulnerabilities, overcome security restrictions, and then transform the PDF format in one among the leading malicious code spread vectors. Analyzing the content of malicious PDF files to extract the main features that characterize the malware identity and behavior, is a fundamental task for modern threat intelligence platforms that need to learn how to automatically identify new attacks. This paper surveys existing state of the art about systems for the detection of malicious PDF files and organizes them in a taxonomy that separately considers the used approaches and the data analyzed to detect the presence of malicious code. © Springer International Publishing AG, part of Springer Nature 2018

The phlebological surgery in elderly patients

The pathogenesis of the lower limbs varicose veins in the elderly patients is the same one as in the juvenile and adult age. What changes is the severity of the clinical picture, because the disease is a chronic pathology and it is aggravated with the passing of the years in absence of prophylaxis and missed or inadequate therapy. Equally the surgical operations on the superficial venous system of the elderly patients from a technical point of view are the same that are practiced in other ages of life. What changes is the anaesthesiological risk, which is increased, because other chronic pathologies are frequently associated with the old ones. Currently both the use of techniques of peripheral anesthesia, as the blocks of the lower limbs nervous trunks, and the introduction of poor toxic anesthetics for the heart in therapeutical practice allow in an inci¬sive way to submit elderly people to surgical procedures. Above all the out-patient hemodynamic surgery of the superficial chronic venous insufficiency, which requires a careful and meticulous instrumental investigation aimed surgical gestures, but simple, effective, of brief duration, has convinced many surgeons of the possibility to operate on the varicose patients of a more and more advance age. On the other hand the rapid postoperative mobiliza¬tion of those sick, in absence of immediate complica¬tions, means that they can be discharged from the hospital on the same day of the operation. This undoubtedly involves positive reflexes on the sanitary expense and it increases at the same time the compliance in terms of motivation and acceptance of the proposed procedure. The elderly patient, perhaps more than the younger adult, once informed of the new anaesthesiological and surgical techniques, gladly gives his consent to the inter¬vention, pleased to return to his own house and tquickly return to his daily occupations. How much I dictate you is translated in our experi¬ence, that is carried out near the Phlebological Center of the Siena University, in a progressive increase in the last 5 years both in absolute terms (223) and percen¬tages (12%) of the number of subjects older than sixty¬five years old that have been submitted to surgical operations for the venous disease. Of all 223 patients, males are 68 and females are 155; 144of them have an age between 66 and 70 years, 73 belonging to the eighty years of life and 6 subject to the ninty. All patients have been operated in Day Hospi¬tal admission. No mortality has been found. Local post-operative complications was encountered in 1,8% of the cases

Evidencia del síndrome neuropático en un estudio neurofisiológico e inmunohistoquímico de las fibras nerviosas en pacientes con síndrome de boca ardiente

espanolIntroduccion: El sindrome de la boca ardiente (SBA) es una enfermedad de frecuente aparicion, caracterizada para un dolor quemante y ardiente en la lengua y en la cavidad oral, en ausencia de alteraciones estructurales macroscopicas de las mucosas. La etiopatogenesis del SBA no es todavia conocida y por lo tanto no presenta un esquema diagnostico claro y bien definido. Material y metodos: Para evaluar la hipotesis que contempla una alteracion de las fibras nerviosas perifericas de pequeno calibre, asociada o no con una alteracion trofica de las mucosas, hemos seleccionados 25 pacientes (7 varones y 18 mujeres, con una edad comprendida entre 36 y 75 anos, una media de 54 anos) afectados por SBA, que llegaron a nuestra clinica para una serie de examenes que suelen realizarse de forma rutinaria en las sindromes de dolor neurologico. En todos los pacientes se ha realizado un cuidadoso examen objetivo y una ortopantomografia, con la finalidad de excluir alteraciones de las mucosas y enfermedades odontologicas. En todos los pacientes se han realizado: examenes hematoquimicos, examenes objetivos neurologicos, teletermografia de la lengua y de la cara, examen cuantitativo de la sensibilidad termica de la lengua, de las manos y de la parte dorsal del pie. Los resultados del examen cuantitativo de la sensibilidad termica de la lengua y de la muneca se confrontaban con una poblacion control homogenea. En una poblacion de 10 pacientes (3 varones y 7 mujeres; de una edad comprendida entre 34 y 53 anos, una media de 49 anos) se ha realizado un biopsia de la parte dorsal de la lengua, la biopsias se han analizado con microscopia optica e inmunofluresencia tras un tratamiento con anticuerpos activos para proteinas neuronales citoplasmaticas (protein gene product 9.5). Resultados: Los datos obtenidos evidenciaban la presencia de una polineuropatia subclinica en el 50% de los pacientes. Especialmente se apreciaban signos de baja funcionalidad de las fibras nerviosas de pequeno calibre de la lengua en casi la mitad de los pacientes examinados. El examen histologico de la mucosa lingual evidenciaba una atrofia discreta en el 70% de los pacientes, mientras que la observacion de las fibras nerviosas de pequeno calibre por medio de la inmunofluoresencia hacia suponer la presencia de alteraciones relacionadas con una polineuropatia de tipo periferico. EnglishAims. Burning pain is considered characteristic of chronic neuropathic pain condition in general, and so me recent data seem to suggest peripheral or central nervous system involvement as possible underlying factor in BMS. This study was designed to determinate if burning mouth symptoms could be originated from a peripheal neuropathy of small diameter nerve fibres. Material and methods. The material of the study consisted of 25 patients (18 female, 7 male, 30-75 years; means 54 years). In all patients there were not: oral muco membranes lesions, oral muco membranes diseases, oral correlated diseases, oral dysfunctions, dental and periodontal diseases. Besides there were: no evidence of central nervous system pathology, no evidence of peripheral nervous system pathology, no presence of organic body disfunctions. AIIpatients didn't show significant alterations of blood investigations. AII patients were undermitted to our protocol including: oral and facial clinical examinations, neurological exam, blood investigations, Mc Gill Pain Questionnaire, VAS (visual analogical scale), biopsy of tongue mucosa with hystological and immunofluorescence exams, quantitative somatosensory thermotest and teletermography examination of tongue mucosa. ResuIts. These examinations have showed subclinical polineurophaty in 50% of patients. In particular were observed a loss of function in small diameter nervous fibres in about 50% of patients. Hystological exam of mucosal tongue revealed a moderate atrophy and alterations of structures. Conclusion. Etiology, pathogenetic processes, clinical and diagnostic approaches, therapeutical resolutions and researches of burning mouth syndrome are not clear yet. The local alterations of small diameter sensitive nerve fibres could cause an increase of oral burning, without muco membranes pathologies. These locallesions could justify the bms clinical symptomatology. The hystological alteration of small diameter sensitive nerve fibres could involve meaningful alterations of thermal reactivity of oral and body surfaces. These clinical reactivities are evident in chronic peripheal neuropathy (diabetes). These conclusions and our study results are still provisory. It will be necessary to estend and to increase our results, comparing our research with other bms etio-pathogenetic hypotesis

Limit Synchronization in Markov Decision Processes

Markov decision processes (MDP) are finite-state systems with both strategic and probabilistic choices. After fixing a strategy, an MDP produces a sequence of probability distributions over states. The sequence is eventually synchronizing if the probability mass accumulates in a single state, possibly in the limit. Precisely, for 0 <= p <= 1 the sequence is p-synchronizing if a probability distribution in the sequence assigns probability at least p to some state, and we distinguish three synchronization modes: (i) sure winning if there exists a strategy that produces a 1-synchronizing sequence; (ii) almost-sure winning if there exists a strategy that produces a sequence that is, for all epsilon > 0, a (1-epsilon)-synchronizing sequence; (iii) limit-sure winning if for all epsilon > 0, there exists a strategy that produces a (1-epsilon)-synchronizing sequence. We consider the problem of deciding whether an MDP is sure, almost-sure, limit-sure winning, and we establish the decidability and optimal complexity for all modes, as well as the memory requirements for winning strategies. Our main contributions are as follows: (a) for each winning modes we present characterizations that give a PSPACE complexity for the decision problems, and we establish matching PSPACE lower bounds; (b) we show that for sure winning strategies, exponential memory is sufficient and may be necessary, and that in general infinite memory is necessary for almost-sure winning, and unbounded memory is necessary for limit-sure winning; (c) along with our results, we establish new complexity results for alternating finite automata over a one-letter alphabet

Clar Sextet Analysis of Triangular, Rectangular and Honeycomb Graphene Antidot Lattices

Pristine graphene is a semimetal and thus does not have a band gap. By making a nanometer scale periodic array of holes in the graphene sheet a band gap may form; the size of the gap is controllable by adjusting the parameters of the lattice. The hole diameter, hole geometry, lattice geometry and the separation of the holes are parameters that all play an important role in determining the size of the band gap, which, for technological applications, should be at least of the order of tenths of an eV. We investigate four different hole configurations: the rectangular, the triangular, the rotated triangular and the honeycomb lattice. It is found that the lattice geometry plays a crucial role for size of the band gap: the triangular arrangement displays always a sizable gap, while for the other types only particular hole separations lead to a large gap. This observation is explained using Clar sextet theory, and we find that a sufficient condition for a large gap is that the number of sextets exceeds one third of the total number of hexagons in the unit cell. Furthermore, we investigate non-isosceles triangular structures to probe the sensitivity of the gap in triangular lattices to small changes in geometry