Cryptanalysis of an MPEG-Video Encryption Scheme Based on Secret Huffman Tables

This paper studies the security of a recently-proposed MPEG-video encryption scheme based on secret Huffman tables. Our cryptanalysis shows that: 1) the key space of the encryption scheme is not sufficiently large against divide-and-conquer (DAC) attack and known-plaintext attack; 2) it is possible to decrypt a cipher-video with a partially-known key, thus dramatically reducing the complexity of the DAC brute-force attack in some cases; 3) its security against the chosen-plaintext attack is very weak. Some experimental results are included to support the cryptanalytic results with a brief discuss on how to improve this MPEG-video encryption scheme.Comment: 8 pages, 4 figure

Ökologischer Weinbau in Deutschland - Feldversuche und praktische Erfahrungen zur Kupferreduzierung

Ableitend aus dem aktuellen Kenntnisstand, den vorgestellten Ergebnissen und vielfältigen Erfahrungen aus der Praxis muss festgestellt werden, dass derzeit keine praxisreifen Kupferersatzstoffe aus den Bereichen anorganische Salze, Pflanzenextrakte und biologische Antagonisten zur Verfügung stehen. Die im Rahmen der vorgestellten Versuche mit einem unformulierten Präparat des biologischen Antagonisten von Plasmopara viticola, Erwinia herbicola, erzielten Ergebnisse machen den Forschungsbedarf in diesem Sektor deutlich. Die Wirkungspotentiale von Erwinia herbicola konnten mit dem unformulierten Versuchsprodukt bei gleichzeitig starkem Infektionsdruck und den realisierten Applikationsintervallen nicht ausgeschöpft werden. Gute Ergebnisse beim Einsatz von Erwinia herbicola Anfang der 90er Jahre belegen die Wirksamkeit dieses Antagonisten, wobei besonders durch entsprechende Formulierung Wirkungssteigerungen erreicht wurden. Um die Existenz des europäischen Bioweinbaus sicherzustellen ist der Erhalt bestimmter Kupferverbindungen im Anhang II der EU-VO 2092/91 derzeit unverzichtbar. Weiterhin ist aufgrund der klimatisch bedingten, an Stärke zunehmenden Infektionsereignisse durch Plasmopara viticola eine Reduzierung der Aufwandmengen unter 3 kg/ha und Jahr in der Praxis nicht vorstellbar. Möglichkeiten zu einer weiteren nationalen Reduzierung des Kupfereinsatzes (< 3 kg/ha) bei hohem Befallsdruck wären derzeit nur nach einer Wiederzulassung von phosphithaltigen Präparaten durch die BBA (Ökofluid-P und Robus sind derzeit nicht als Pflanzenstärkungsmittel registriert) gegeben und im Sinne der Praxis verantwortbar, wobei die Akzeptanz dieser Präparate durch die Bioanbauverbände gegeben sein müsste. Bei einer Eingruppierung als Pflanzenschutzmittel wäre eine Aufnahme in den Anhang II der EU Verordnung zu beantragen. Bereits bekannte Ergebnisse aus den 90er Jahren und aktuelle Untersuchungen zu Phosphonatrückständen in den Weinen aus den vorgestellten Versuchen sowie weiteren Proben aus der Praxis belegen die bestehende Rückstandsproblematik. Aktuell laufende Untersuchungen weisen jedoch darauf hin, dass dieser Problematik durch eine Begrenzung des Einsatzes bis in den Bereich des Entwicklungsstadiums „Erbsengröße“ (BBCH 75) sowie den Einsatz von Präparaten mit geringerer Phosphonatkonzentration deutlich entgegengewirkt werden kann. Die Untersuchungen hierzu sind noch nicht abgeschlossen und werden fortgesetzt

Instability of the rhodium magnetic moment as origin of the metamagnetic phase transition in alpha-FeRh

Based on ab initio total energy calculations we show that two magnetic states of rhodium atoms together with competing ferromagnetic and antiferromagnetic exchange interactions are responsible for a temperature induced metamagnetic phase transition, which experimentally is observed for stoichiometric alpha-FeRh. A first-principle spin-based model allows to reproduce this first-order metamagnetic transition by means of Monte Carlo simulations. Further inclusion of spacial variation of exchange parameters leads to a realistic description of the experimental magneto-volume effects in alpha-FeRh.Comment: 10 pages, 13 figures, accepted for publication in Phys. Rev.

Associação de espécies florestais com forrageiras para ocupação de áreas degradadas.

bitstream/item/57383/1/CPATU-PA145.pd

The PKC, HOG and Ca2+ signalling pathways co-ordinately regulate chitin synthesis in Candida albicans

Open Access via PMC2649417Peer reviewedPublisher PD

Інвестиційний клімат України та шляхи його покращення

Background —Hypertrophic cardiomyopathy is a myocardial disorder resulting from inherited sarcomeric dysfunction. We report a mutation in the myosin-binding protein-C (MyBP-C) gene, its clinical consequences in a large family, and myocardial tissue findings that may provide insight into the mechanism of disease. Methods and Results —History and clinical status (examination, ECG, and echocardiography) were assessed in 49 members of a multigeneration family. Linkage analysis implicated the MyBP-C gene on chromosome 11. Myocardial mRNA, genomic MyBP-C DNA, and the myocardial proteins of patients and healthy relatives were analyzed. A single guanine nucleotide insertion in exon 25 of the MyBP-C gene resulted in the loss of 40 bases in abnormally processed mRNA. A 30-kDa truncation at the C-terminus of the protein was predicted, but a polypeptide of the expected size (≈95 kDa) was not detected by immunoblot testing. The disease phenotype in this family was characterized in detail: only 10 of 27 gene carriers fulfilled diagnostic criteria. Five carriers showed borderline hypertrophic cardiomyopathy, and 12 carriers were asymptomatic, with normal ECG and echocardiograms. The age of onset in symptomatic patients was late (29 to 68 years). In 2 patients, outflow obstruction required surgery. Two family members experienced premature sudden cardiac death, but survival at 50 years was 95%. Conclusions —Penetrance of this mutation was incomplete and age-dependent. The large number of asymptomatic carriers and the good prognosis support the interpretation of benign disease. </jats:p

The onset of magnetic order in fcc-Fe films on Cu(100)

On the basis of a first-principles electronic structure theory of finite temperature metallic magnetism in layered materials, we investigate the onset of magnetic order in thin (2-8 layers) fcc-Fe films on Cu(100) substrates. The nature of this ordering is altered when the systems are capped with copper. Indeed we find an oscillatory dependence of the Curie temperatures as a function of Cu-cap thickness, in excellent agreement with experimental data. The thermally induced spin-fluctuations are treated within a mean-field disordered local moment (DLM) picture and give rise to layer-dependent `local exchange splittings' in the electronic structure even in the paramagnetic phase. These features determine the magnetic intra- and interlayer interactions which are strongly influenced by the presence and extent of the Cu cap.Comment: 13 pages, 3 figure

Magnetic properties of X-Pt (X=Fe,Co,Ni) alloy systems

We have studied the electronic and magnetic properties of Fe-Pt, Co-Pt and Ni-Pt alloy systems in ordered and disordered phases. The influence of various exchange-correlation functionals on values of equilibrium lattice parameters and magnetic moments in ordered Fe-Pt, Co-Pt and Ni-Pt alloys have been studied using linearized muffin-tin orbital method. The electronic structure calculations for the disordered alloys have been carried out using augmented space recursion technique in the framework of tight binding linearized muffin-tin orbital method. The effect of short range order has also been studied in the disordered phase of these systems. The results show good agreements with available experimental values.Comment: 21 pages, 4 eps figures, accepted for publication in Journal of Physics Condensed Matte

Noncollinear magnetic ordering in small Chromium Clusters

We investigate noncollinear effects in antiferromagnetically coupled clusters using the general, rotationally invariant form of local spin-density theory. The coupling to the electronic degrees of freedom is treated with relativistic non-local pseudopotentials and the ionic structure is optimized by Monte-Carlo techniques. We find that small chromium clusters (N \le 13) strongly favor noncollinear configurations of their local magnetic moments due to frustration. This effect is associated with a significantly lower total magnetization of the noncollinear ground states, ameliorating the disagreement between Stern-Gerlach measurements and previous collinear calculations for Cr_{12} and Cr_{13}. Our results further suggest that the trend to noncollinear configurations might be a feature common to most antiferromagnetic clusters.Comment: 9 pages, RevTeX plus .eps/.ps figure

Spin fluctuations in nearly magnetic metals from ab-initio dynamical spin susceptibility calculations:application to Pd and Cr95V5

We describe our theoretical formalism and computational scheme for making ab-initio calculations of the dynamic paramagnetic spin susceptibilities of metals and alloys at finite temperatures. Its basis is Time-Dependent Density Functional Theory within an electronic multiple scattering, imaginary time Green function formalism. Results receive a natural interpretation in terms of overdamped oscillator systems making them suitable for incorporation into spin fluctuation theories. For illustration we apply our method to the nearly ferromagnetic metal Pd and the nearly antiferromagnetic chromium alloy Cr95V5. We compare and contrast the spin dynamics of these two metals and in each case identify those fluctuations with relaxation times much longer than typical electronic `hopping times'Comment: 21 pages, 9 figures. To appear in Physical Review B (July 2000