156 research outputs found
1st Place Solution to MultiEarth 2023 Challenge on Multimodal SAR-to-EO Image Translation
The Multimodal Learning for Earth and Environment Workshop (MultiEarth 2023)
aims to harness the substantial amount of remote sensing data gathered over
extensive periods for the monitoring and analysis of Earth's ecosystems'health.
The subtask, Multimodal SAR-to-EO Image Translation, involves the use of robust
SAR data, even under adverse weather and lighting conditions, transforming it
into high-quality, clear, and visually appealing EO data. In the context of the
SAR2EO task, the presence of clouds or obstructions in EO data can potentially
pose a challenge. To address this issue, we propose the Clean Collector
Algorithm (CCA), designed to take full advantage of this cloudless SAR data and
eliminate factors that may hinder the data learning process. Subsequently, we
applied pix2pixHD for the SAR-to-EO translation and Restormer for image
enhancement. In the final evaluation, the team 'CDRL' achieved an MAE of
0.07313, securing the top rank on the leaderboard
Breakdown of the interlayer coherence in twisted bilayer graphene
Coherent motion of the electrons in the Bloch states is one of the
fundamental concepts of the charge conduction in solid state physics. In
layered materials, however, such a condition often breaks down for the
interlayer conduction, when the interlayer coupling is significantly reduced by
e.g. large interlayer separation. We report that complete suppression of
coherent conduction is realized even in an atomic length scale of layer
separation in twisted bilayer graphene. The interlayer resistivity of twisted
bilayer graphene is much higher than the c-axis resistivity of Bernal-stacked
graphite, and exhibits strong dependence on temperature as well as on external
electric fields. These results suggest that the graphene layers are
significantly decoupled by rotation and incoherent conduction is a main
transport channel between the layers of twisted bilayer graphene.Comment: 5 pages, 3 figure
Self-Updatable Encryption: Time Constrained Access Control with Hidden Attributes and Better Efficiency
Revocation and key evolving paradigms are central issues in cryptography, and in PKI in particular. A novel concern related to these areas was raised in the recent work of Sahai, Seyalioglu, and Waters (Crypto 2012) who noticed that revoking past keys should at times (e.g., the scenario of cloud storage) be accompanied by revocation of past ciphertexts (to prevent unread ciphertexts from being read by revoked users). They introduced revocable-storage attribute-based encryption (RS-ABE) as a good access control mechanism for cloud storage. RS-ABE protects against the revoked users not only the future data by supporting key-revocation but also the past data by supporting ciphertext-update, through which a ciphertext at time can be updated to a new ciphertext at time using only the public key.
Motivated by this pioneering work, we ask whether it is possible to have a modular approach, which includes a primitive for time managed ciphertext update as a primitive. We call encryption which supports this primitive a ``self-updatable encryption\u27\u27 (SUE). We then suggest a modular cryptosystems design methodology based on three sub-components: a primary encryption scheme, a key-revocation mechanism, and a time-evolution mechanism which controls the ciphertext self-updating via an SUE method, coordinated with the revocation (when needed). Our goal in this is to allow the self-updating ciphertext component to take part in the design of new and improved cryptosystems and protocols in a flexible fashion. Specifically, we achieve the following results:
- We first introduce a new cryptographic primitive called self-updatable encryption (SUE), realizing a time-evolution mechanism. In SUE, a ciphertext and a private key are associated with time. A user can decrypt a ciphertext if its time is earlier than that of his private key. Additionally, anyone (e.g., a cloud server) can update the ciphertext to a ciphertext with a newer time. We also construct an SUE scheme and prove its full security under static assumptions.
- Following our modular approach, we present a new RS-ABE scheme with shorter ciphertexts than that of Sahai et al. and prove its security. The length efficiency is mainly due to our SUE scheme and the underlying modularity.
- We apply our approach to predicate encryption (PE) supporting attribute-hiding property, and obtain a revocable-storage PE (RS-PE) scheme that is selectively-secure.
- We further demonstrate that SUE is of independent interest, by showing it can be used for timed-release encryption (and its applications), and for augmenting key-insulated encryption with forward-secure storage
Crystallization and preliminary X-ray analysis of neoagarobiose hydrolase from Saccharophagus degradans 2-40
Many agarolytic bacteria degrade agar polysaccharide into the disaccharide unit neoagarobiose [O-3,6-anhydro-α-L-galactopyranosyl-(1→3)-D-galactose] using various β-agarases. Neoagarobiose hydrolase is an enzyme that acts on the α-1,3 linkage in neoagarobiose to yield D-galactose and 3,6-anhydro-L-galactose. This activity is essential in both the metabolism of agar by agarolytic bacteria and the production of fermentable sugars from agar biomass for bioenergy production. Neoagarobiose hydrolase from the marine bacterium Saccharophagus degradans 2-40 was overexpressed in Escherichia coli and crystallized in the monoclinic space group C2, with unit-cell parameters a = 129.83, b = 76.81, c = 90.11 Å, β = 101.86°. The crystals diffracted to 1.98 Å resolution and possibly contains two molecules in the asymmetric unit
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