147 research outputs found
Shear Behavior of Screw Connection between Cold-Formed Steel and Gypsum Sheathing at Elevated Temperatures
The screw connections between cold-formed steel (CFS) and gypsum sheathing play an important role in the axial and lateral performance of CFS wall panels. Previous researches were mainly focus on the shear behavior of such screw connections at room temperature. This paper carried out a preliminary experimental investigation on the mechanical performance of screw connections with single layer gypsum sheathing at elevated temperatures. Limited to the cavity dimension of the furnace, the single-lap test of CFS coupon -fastener-sheathing connection was adopted and compared with the previous test results of sheathing-to-profile screw connections at room temperature. The failure of screw connections with single layer gypsum sheathing was identified as the breaking of the sheathing edge at elevated temperatures and a sharp decrease of the shear strength was observed beyond 150 °C. In addition, the load-displacement curves of screw connections were well predicted by an exponential model with the post-peak branch at elevated temperatures
A study of conceptual language similarity: comparison and evaluation
An interesting line of research in natural language processing (NLP) aims to
incorporate linguistic typology to bridge linguistic diversity and assist the
research of low-resource languages. While most works construct linguistic
similarity measures based on lexical or typological features, such as word
order and verbal inflection, recent work has introduced a novel approach to
defining language similarity based on how they represent basic concepts, which
is complementary to existing similarity measures. In this work, we study the
conceptual similarity in detail and evaluate it extensively on a binary
classification task
Regulation of retrotranslocation by p97-associated deubiquitinating enzyme ataxin-3
Misfolded proteins of the endoplasmic reticulum undergo retrotranslocation to enter the cytosol where they are degraded by the proteasome. Retrotranslocation of many substrates requires an ATPase complex consisting of the p97 ATPase and a dimeric cofactor, Ufd1-Npl4. We report that efficient elimination of misfolded ER proteins also involves ataxin-3 (atx3), a p97-associated deubiquitinating enzyme mutated in type-3 spinocerebellar ataxia. Overexpression of an atx3 mutant defective in deubiquitination inhibits the degradation of misfolded ER proteins and triggers ER stress. Misfolded polypeptides stabilized by mutant atx3 are accumulated in part as polyubiquitinated form, suggesting an involvement of its deubiquitinating activity in ER-associated protein degradation regulation. We demonstrate that atx3 transiently associates with the ER membrane via p97 and the recently identified Derlin–VIMP complex, and its release from the membrane appears to be governed by both the p97 ATPase cycle and its own deubiquitinating activity. We present evidence that atx3 may promote p97-associated deubiquitination to facilitate the transfer of polypeptides from p97 to the proteasome
Crosslingual Transfer Learning for Low-Resource Languages Based on Multilingual Colexification Graphs
In comparative linguistics, colexification refers to the phenomenon of a
lexical form conveying two or more distinct meanings. Existing work on
colexification patterns relies on annotated word lists, limiting scalability
and usefulness in NLP. In contrast, we identify colexification patterns of more
than 2,000 concepts across 1,335 languages directly from an unannotated
parallel corpus. We then propose simple and effective methods to build
multilingual graphs from the colexification patterns: ColexNet and ColexNet+.
ColexNet's nodes are concepts and its edges are colexifications. In ColexNet+,
concept nodes are additionally linked through intermediate nodes, each
representing an ngram in one of 1,334 languages. We use ColexNet+ to train
\overrightarrow{\mbox{ColexNet+}}, high-quality multilingual embeddings that
are well-suited for transfer learning. In our experiments, we first show that
ColexNet achieves high recall on CLICS, a dataset of crosslingual
colexifications. We then evaluate \overrightarrow{\mbox{ColexNet+}} on
roundtrip translation, sentence retrieval and sentence classification and show
that our embeddings surpass several transfer learning baselines. This
demonstrates the benefits of using colexification as a source of information in
multilingual NLP.Comment: EMNLP 2023 Finding
Structural basis for regulation of the nucleo-cytoplasmic distribution of Bag6 by TRC35
The metazoan protein BCL2-associated athanogene cochaperone 6 (Bag6) forms a hetero-trimeric complex with ubiquitin-like 4A and transmembrane domain recognition complex 35 (TRC35). This Bag6 complex is involved in tail-anchored protein targeting and various protein quality-control pathways in the cytosol as well as regulating transcription and histone methylation in the nucleus. Here we present a crystal structure of Bag6 and its cytoplasmic retention factor TRC35, revealing that TRC35 is remarkably conserved throughout the opisthokont lineage except at the C-terminal Bag6-binding groove, which evolved to accommodate Bag6, a unique metazoan factor. While TRC35 and its fungal homolog, guided entry of tail-anchored protein 4 (Get4), utilize a conserved hydrophobic patch to bind their respective partners, Bag6 wraps around TRC35 on the opposite face relative to the Get4–5 interface. We further demonstrate that TRC35 binding is critical not only for occluding the Bag6 nuclear localization sequence from karyopherin α to retain Bag6 in the cytosol but also for preventing TRC35 from succumbing to RNF126-mediated ubiquitylation and degradation. The results provide a mechanism for regulation of Bag6 nuclear localization and the functional integrity of the Bag6 complex in the cytosol
A Crosslingual Investigation of Conceptualization in 1335 Languages
Languages differ in how they divide up the world into concepts and words;
e.g., in contrast to English, Swahili has a single concept for `belly' and
`womb'. We investigate these differences in conceptualization across 1,335
languages by aligning concepts in a parallel corpus. To this end, we propose
Conceptualizer, a method that creates a bipartite directed alignment graph
between source language concepts and sets of target language strings. In a
detailed linguistic analysis across all languages for one concept (`bird') and
an evaluation on gold standard data for 32 Swadesh concepts, we show that
Conceptualizer has good alignment accuracy. We demonstrate the potential of
research on conceptualization in NLP with two experiments. (1) We define
crosslingual stability of a concept as the degree to which it has 1-1
correspondences across languages, and show that concreteness predicts
stability. (2) We represent each language by its conceptualization pattern for
83 concepts, and define a similarity measure on these representations. The
resulting measure for the conceptual similarity of two languages is
complementary to standard genealogical, typological, and surface similarity
measures. For four out of six language families, we can assign languages to
their correct family based on conceptual similarity with accuracy between 54%
and 87%.Comment: ACL 202
Modeling Clinically Heterogeneous Presenilin Mutations with Transgenic Drosophila
SummaryTo assess the potential of Drosophila to analyze clinically graded aspects of human disease, we developed a transgenic fly model to characterize Presenilin (PS) gene mutations that cause early-onset familial Alzheimer's disease (FAD). FAD exhibits a wide range in severity defined by ages of onset from 24 to 65 years [1]. PS FAD mutants have been analyzed in mammalian cell culture, but conflicting data emerged concerning correlations between age of onset and PS biochemical activity [2–4]. Choosing from over 130 FAD mutations in Presenilin-1, we introduced 14 corresponding mutations at conserved residues in Drosophila Presenilin (Psn) and assessed their biological activity in transgenic flies by using genetic, molecular, and statistical methods. Psn FAD mutant activities were tightly linked to their age-of-onset values, providing evidence that disease severity in humans primarily reflects differences in PS mutant lesions rather than contributions from unlinked genetic or environmental modifiers. Our study establishes a precedent for using transgenic Drosophila to study clinical heterogeneity in human disease
Bag6 complex contains a minimal tail-anchor–targeting module and a mock BAG domain
BCL2-associated athanogene cochaperone 6 (Bag6) plays a central role in cellular homeostasis in a diverse array of processes and is part of the heterotrimeric Bag6 complex, which also includes ubiquitin-like 4A (Ubl4A) and transmembrane domain recognition complex 35 (TRC35). This complex recently has been shown to be important in the TRC pathway, the mislocalized protein degradation pathway, and the endoplasmic reticulum-associated degradation pathway. Here we define the architecture of the Bag6 complex, demonstrating that both TRC35 and Ubl4A have distinct C-terminal binding sites on Bag6 defining a minimal Bag6 complex. A crystal structure of the Bag6–Ubl4A dimer demonstrates that Bag6–BAG is not a canonical BAG domain, and this finding is substantiated biochemically. Remarkably, the minimal Bag6 complex defined here facilitates tail-anchored substrate transfer from small glutamine-rich tetratricopeptide repeat-containing protein α to TRC40. These findings provide structural insight into the complex network of proteins coordinated by Bag6
USP13 antagonizes gp78 to maintain functionality of a chaperone in ER-associated degradation
Physiological adaptation to proteotoxic stress in the endoplasmic reticulum (ER) requires retrotranslocation of misfolded proteins into the cytoplasm for ubiquitination and elimination by ER-associated degradation (ERAD). A surprising paradox emerging from recent studies is that ubiquitin ligases (E3s) and deubiquitinases (DUBs), enzymes with opposing activities, can both promote ERAD. Here we demonstrate that the ERAD E3 gp78 can ubiquitinate not only ERAD substrates, but also the machinery protein Ubl4A, a key component of the Bag6 chaperone complex. Remarkably, instead of targeting Ubl4A for degradation, polyubiquitination is associated with irreversible proteolytic processing and inactivation of Bag6. Importantly, we identify USP13 as a gp78-associated DUB that eliminates ubiquitin conjugates from Ubl4A to maintain the functionality of Bag6. Our study reveals an unexpected paradigm in which a DUB prevents undesired ubiquitination to sharpen substrate specificity for an associated ubiquitin ligase partner and to promote ER quality control
A Planar Low-Profile Meander Antenna Design for Wireless Terminal Achieving Low RF Interference and High Isolation in Multi-Antenna Systems
In this article, a meander line internal antenna used for wireless terminal is proposed. The current of this antenna is mostly distributed on the antenna radiator itself, rather than on the main board of the wireless device. As a result, the chance of having radiofrequency (RF) interference issues, which usually result in receiver desensitization in wireless radios, can be significantly reduced. The antenna has good radiation performance in the vertical polarization with a low physical profile, compared with the existing antenna designs for typical wireless terminals. The antenna has efficiency similar to the monopole antenna with much less reference/ground plane dependence, achieving lower RF interference, which is demonstrated by the noise coupling measurements in a predefined digital clock - antenna configuration. Furthermore, the mutual coupling (i.e., isolation) between two such antennas is studied and the envelope correlation coefficient between the two antennas is found to be low. A router assembled with the two proposed antennas is tested, and the total isotropic sensitivity is found lower compared with monopole antennas, due to the characteristics of low RF interference and high isolation of the proposed antenna
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