2,933 research outputs found
Practical Schemes For Privacy & Security Enhanced RFID
Proper privacy protection in RFID systems is important. However, many of the
schemes known are impractical, either because they use hash functions instead
of the more hardware efficient symmetric encryption schemes as a efficient
cryptographic primitive, or because they incur a rather costly key search time
penalty at the reader. Moreover, they do not allow for dynamic, fine-grained
access control to the tag that cater for more complex usage scenarios.
In this paper we investigate such scenarios, and propose a model and
corresponding privacy friendly protocols for efficient and fine-grained
management of access permissions to tags. In particular we propose an efficient
mutual authentication protocol between a tag and a reader that achieves a
reasonable level of privacy, using only symmetric key cryptography on the tag,
while not requiring a costly key-search algorithm at the reader side. Moreover,
our protocol is able to recover from stolen readers.Comment: 18 page
On the necessity of complexity
Wolfram's Principle of Computational Equivalence (PCE) implies that universal
complexity abounds in nature. This paper comprises three sections. In the first
section we consider the question why there are so many universal phenomena
around. So, in a sense, we week a driving force behind the PCE if any. We
postulate a principle GNS that we call the Generalized Natural Selection
Principle that together with the Church-Turing Thesis is seen to be equivalent
to a weak version of PCE. In the second section we ask the question why we do
not observe any phenomena that are complex but not-universal. We choose a
cognitive setting to embark on this question and make some analogies with
formal logic. In the third and final section we report on a case study where we
see rich structures arise everywhere.Comment: 17 pages, 3 figure
Ramsar Policy Brief No. 5. Restoring drained peatlands: A necessary step to achieve global climate goals
Peatlands cover about 400 million hectares (ha), or 3% of the land surface of our planet. Yet they store more carbon, more effectively and for longer periods, than any other ecosystem on land. Intact peatlands also provide essential ecosystem services such as regulating water cycles, purifying water, and supporting a wealth of biodiversity. Since peat is hidden below ground, it is often unrecognised and can be damaged unknowingly. New, large peatland areas are still being discovered including forest-covered peatlands in the tropics.
Around 50 million ha of peatlands globally are currently drained and have been transformed to grazing land, forestry land and cropland, used for peat extraction or impacted by infrastructure. These drained peatlands are responsible for approximately 4% (2 Gt CO2 -eq/year) of all anthropogenic greenhouse gas emissions. Achieving the climate goals of the Paris Agreement requires protection of all remaining intact peatland and rapid restoration of almost all drained peatlands.
This will also contribute to delivering the Sustainable Development Goals (SDGs), in particular SDG 6, Target 6.6, on protecting and restoring water related ecosystems and SDG 15, Targets 15.1, on conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services, as well as 15.5 on reducing degradation of natural habitats. The United Nations Decade on Ecosystem Restoration 2021-2030 provides the opportunity to rapidly scale up efforts
Functional consequences of sphingomyelinase-induced changes in erythrocyte membrane structure.
Inflammation enhances the secretion of sphingomyelinases (SMases). SMases catalyze the hydrolysis of sphingomyelin into phosphocholine and ceramide. In erythrocytes, ceramide formation leads to exposure of the removal signal phosphatidylserine (PS), creating a potential link between SMase activity and anemia of inflammation. Therefore, we studied the effects of SMase on various pathophysiologically relevant parameters of erythrocyte homeostasis. Time-lapse confocal microscopy revealed a SMase-induced transition from the discoid to a spherical shape, followed by PS exposure, and finally loss of cytoplasmic content. Also, SMase treatment resulted in ceramide-associated alterations in membrane-cytoskeleton interactions and membrane organization, including microdomain formation. Furthermore, we observed increases in membrane fragility, vesiculation and invagination, and large protein clusters. These changes were associated with enhanced erythrocyte retention in a spleen-mimicking model. Erythrocyte storage under blood bank conditions and during physiological aging increased the sensitivity to SMase. A low SMase activity already induced morphological and structural changes, demonstrating the potential of SMase to disturb erythrocyte homeostasis. Our analyses provide a comprehensive picture in which ceramide-induced changes in membrane microdomain organization disrupt the membrane-cytoskeleton interaction and membrane integrity, leading to vesiculation, reduced deformability, and finally loss of erythrocyte content. Understanding these processes is highly relevant for understanding anemia during chronic inflammation, especially in critically ill patients receiving blood transfusions
Active microwave users working group program planning
A detailed programmatic and technical development plan for active microwave technology was examined in each of four user activities: (1) vegetation; (2) water resources and geologic applications, and (4) oceanographic applications. Major application areas were identified, and the impact of each application area in terms of social and economic gains were evaluated. The present state of knowledge of the applicability of active microwave remote sensing to each application area was summarized and its role relative to other remote sensing devices was examined. The analysis and data acquisition techniques needed to resolve the effects of interference factors were reviewed to establish an operational capability in each application area. Flow charts of accomplished and required activities in each application area that lead to operational capability were structured
Automatic rebuilding and optimization of crystallographic structures in the Protein Data Bank
Motivation: Macromolecular crystal structures in the Protein Data Bank (PDB) are a key source of structural insight into biological processes. These structures, some >30 years old, were constructed with methods of their era. With PDB_REDO, we aim to automatically optimize these structures to better fit their corresponding experimental data, passing the benefits of new methods in crystallography on to a wide base of non-crystallographer structure users
The Texel textile find revisited:the testing of cleaning and drying processes for historical wet rags
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