Superconducting properties of novel BiSe2_{2}-based layered LaO1−x_{1-x}Fx_{x}BiSe2_{2} single crystals

F-doped LaOBiSe$_{2}$ superconducting single crystals with typical size of 2$\times$4$\times$0.2 mm$^{3}$ are successfully grown by flux method and the superconducting properties are studied. Both the superconducting transition temperature and the shielding volume fraction are effectively improved with fluorine doping. The LaO$_{0.48}$F$_{0.52}$BiSe$_{1.93}$ sample exhibits zero-resistivity at 3.7 K, which is higher than that of the LaO$_{0.5}$F$_{0.5}$BiSe$_{2}$ polycrystalline sample (2.4K). Bulk superconductivity is confirmed by a clear specific-heat jump at the associated temperature. The samples exhibit strong anisotropy and the anisotropy parameter is about 30, as estimated by the upper critical field and effective mass modelComment: 5 pages, 5 figures, 2 tables, accepted for publication in Europhysics Lette

Substrate specificity provides insights into the sugar donor recognition mechanism of O-GlcNAc transferase (OGT).

O-Linked β-N-acetylglucosaminyl transferase (OGT) plays an important role in the glycosylation of proteins, which is involved in various cellular events. In human, three isoforms of OGT (short OGT [sOGT]; mitochondrial OGT [mOGT]; and nucleocytoplasmic OGT [ncOGT]) share the same catalytic domain, implying that they might adopt a similar catalytic mechanism, including sugar donor recognition. In this work, the sugar-nucleotide tolerance of sOGT was investigated. Among a series of uridine 5'-diphosphate-N-acetylglucosamine (UDP-GlcNAc) analogs tested using the casein kinase II (CKII) peptide as the sugar acceptor, four compounds could be used by sOGT, including UDP-6-deoxy-GlcNAc, UDP-GlcNPr, UDP-6-deoxy-GalNAc and UDP-4-deoxy-GlcNAc. Determined values of Km showed that the substitution of the N-acyl group, deoxy modification of C6/C4-OH or epimerization of C4-OH of the GlcNAc in UDP-GlcNAc decreased its affinity to sOGT. A molecular docking study combined with site-directed mutagenesis indicated that the backbone carbonyl oxygen of Leu653 and the hydroxyl group of Thr560 in sOGT contributed to the recognition of the sugar moiety via hydrogen bonds. The close vicinity between Met501 and the N-acyl group of GlcNPr, as well as the hydrophobic environment near Met501, were responsible for the selective binding of UDP-GlcNPr. These findings illustrate the interaction of OGT and sugar nucleotide donor, providing insights into the OGT catalytic mechanism

Magneto Transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3: Ag Polycrystalline Composites

We report the synthesis, (micro)structural, magneto-transport and magnetization of polycrystalline La2/3Ca1/3MnO3:Agx composites with x = 0.0, 0.1, 0.2, 0.3 and 0.4. The temperature coefficient of resistance (TCR) near ferromagnetic (FM) transition is increased significantly with addition of Ag. The FM transition temperature (TFM) is also increased slightly with Ag addition. Magneto-transport measurements revealed that magneto-resistance MR is found to be maximum near TFM. Further the increased MR of up to 60% is seen above 300 K for higher silver added samples in an applied field of 7 Tesla. Sharp TCR is seen near TFM with highest value of up to 15 % for Ag (0.4) sample, which is an order of magnitude higher than as for present pristine sample and best value yet reported for any polycrystalline LCMO compound. Increased TCR, TFM and significant above room temperature MR of La2/3Ca1/3MnO3:Agx composites is explained on the basis of improved grains size and connectivity with silver addition in the matrix. Better coupled FM domains and nearly conducting grain boundaries give rise to improved physical properties of the La2/3Ca1/3MnO3 manganites.Comment: 16 pages Text + Figs. ACCEPTED: Solid State Communications (Sept. 2006

Magnetic properties of the ferrimagnetic cobaltite CaBaCo4O7

The magnetic properties of the ferrimagnetic cobaltite CaBaCo$_4$O$_7$ are systematically investigated. We find that the susceptibility exhibits a downward deviation below $\sim$ 360 K, suggesting the occurrence of short range magnetic correlations at temperature well above $T_C$. The effective moment is determined to be 4.5 $\mu_B$/f.u, which is consistent with that expected for the Co$^{2+}$/Co$^{3+}$ high spin species. Using a criterion given by Banerjee [Phys. Lett. \textbf{12}, 16 (1964)], we demonstrate that the paramagnetic to ferrimagnetic transition in CaBaCo$_4$O$_7$ has a first order character.Comment: 9 pages, 4 figures. To be published in Solid State Communication

From AADL to Timed Abstract State Machines: A Verified Model Transformation

International audienceArchitecture Analysis and Design Language (AADL) is an architecture description language standard for embedded real-time systems widely used in the avionics and aerospace industry to model safety-critical applications. To verify and analyze the AADL models, model transformation technologies are often used to automatically extract a formal specification suitable for analysis and verification. In this process, it remains a challenge to prove that the model transformation preserves the semantics of the initial AADL model or, at least, some of the specific properties or requirements it needs to satisfy. This paper presents a machine checked semantics-preserving transformation of a subset of AADL (including periodic threads, data port communications, mode changes, and the AADL behavior annex) into Timed Abstract State Machines (TASM). The AADL standard itself lacks at present a formal semantics to make this translation validation possible. Our contribution is to bridge this gap by providing two formal semantics for the subset of AADL. The execution semantics provided by the AADL standard is formalized as Timed Transition Systems (TTS). This formalization gives a reference expression of AADL semantics which can be compared with the TASM-based translation (for verification purpose). Finally, the verified transformation is mechanized in the theorem prover Coq

SECURE BOOTSTRAPPING AND ACCESS CONTROL IN NDN-BASED SMART HOME SYSTEMS

Smart home systems utilize network-enabled sensors to collect environmental data and provide various services to home residents. Such a system must be designed with security mechanisms to protect the safety and privacy of the residents. More specifically, we need to secure the production, dissemination, and consumption of smart home data, as well as prevent any unauthorized access to the services provided by the system. In this work, we study how to build a secure smart home system in the context of Named Data Networking, a future Internet architecture that has unique advantages in securing Internet of Things. We focus on solving two security problems: (a) mutual authentication between a new device and an existing smart home system to bootstrap the device, and (b) controlling access to smart home data. We designed a naming hierarchy for a smart home system and the corresponding trust model. Based on the naming and trust model, we designed bootstrapping protocols which enforce mutual cryptographic challenges, and a programming template which facilitates Name-based Access Control. We have designed and implemented an application that incorporates these solutions. Evaluation result shows: (a) the bootstrapping protocols can defend against replay attacks with a small computation overhead, and (b) Name-Based Access Control can provide accurate time schedules to restrict access to fine-grained data types with a small computation overhead

Establishing a co-production framework between researchers and the autistic community: embracing the neurodiversity paradigm

Autism research is evolving from a medical paradigm， which emphasizes deficits and interventions， to a neurodiversity paradigm that values autism as an integral part of human diversity. Historically， the medical paradigm’s focus on “rescue” efforts has distanced researchers from the autistic community， often failing to address the community’s real needs. In contrast， the neurodiversity paradigm advocates a comprehensive understanding of autism and the adoption of participatory research practices. This shift encourages active collaboration between researchers and autistic individuals， fostering inclusive knowledge production that is both meaningful and impactful for the autistic community. However， achieving this collaborative approach requires dismantling social barriers， such as power imbalances， that hinders effective partnership. This article explores the principles and practice of a neurodiversity-aligned participatory research approach and proposes a co-production framework designed to support researchers and the autistic community in advancing autism research that is relevant， respectful， and responsive