654 research outputs found
Upconversion Plasmonic Lasing from an Organolead Trihalide Perovskite Nanocrystal with Low Threshold
The understanding of nonlinear lightâmatter interactions at the nanoscale has fueled worldwide interest in upconversion emission for imaging, lasing, and sensing. Upconversion lasers with anti-Stokes-type emission with various designs have been reported. However, reducing the volume and lasing threshold of such lasers to the nanoscale level is a fundamental photonics challenge. Here, we demonstrate that the upconversion efficiency can be improved by exploiting single-mode upconversion lasing from a single organo-lead halide perovskite nanocrystal in a resonance-adjustable plasmonic nanocavity. This upconversion plasmonic nanolaser has a very low lasing threshold (10 ÎźJ cmâťÂ˛) and a calculated ultrasmall mode volume (âź0.06 Ν³) at 6 K. To provide the unique feature for lasing action, a temporal coherence signature of the upconversion plasmonic nanolasing was determined by measuring the second-order correlation function. The localized-electromagnetic-field confinement can be tailored in titanium nitride resonance-adjustable nanocavities, enhancing the pump-photon absorption and upconverted photon emission rate to achieve lasing. The proof-of-concept results significantly expand the performance of upconversion nanolasers, which are useful in applications such as on-chip, coherent, nonlinear optics, information processing, data storage, and sensing
The Vibrio cholerae var regulon encodes a metallo-β-lactamase and an antibiotic efflux pump, which are regulated by VarR, a LysR-type transcription factor
The genome sequence of V. cholerae O1 Biovar Eltor strain N16961 has revealed a putative antibiotic resistance (var) regulon that is predicted to encode a transcriptional activator (VarR), which is divergently transcribed relative to the putative resistance genes for both a metallo-β-lactamase (VarG) and an antibiotic efflux-pump (VarABCDEF). We sought to test whether these genes could confer antibiotic resistance and are organised as a regulon under the control of VarR. VarG was overexpressed and purified and shown to have β-lactamase activity against penicillins, cephalosporins and carbapenems, having the highest activity against meropenem. The expression of VarABCDEF in the Escherichia coli (ÎacrAB) strain KAM3 conferred resistance to a range of drugs, but most significant resistance was to the macrolide spiramycin. A gel-shift analysis was used to determine if VarR bound to the promoter regions of the resistance genes. Consistent with the regulation of these resistance genes, VarR binds to three distinct intergenic regions, varRG, varGA and varBC located upstream and adjacent to varG, varA and varC, respectively. VarR can act as a repressor at the varRG promoter region; whilst this repression was relieved upon addition of β-lactams, these did not dissociate the VarR/varRG-DNA complex, indicating that the de-repression of varR by β-lactams is indirect. Considering that the genomic arrangement of VarR-VarG is strikingly similar to that of AmpR-AmpC system, it is possible that V. cholerae has evolved a system for resistance to the newer β-lactams that would prove more beneficial to the bacterium in light of current selective pressures
XAIR: A Framework of Explainable AI in Augmented Reality
Explainable AI (XAI) has established itself as an important component of
AI-driven interactive systems. With Augmented Reality (AR) becoming more
integrated in daily lives, the role of XAI also becomes essential in AR because
end-users will frequently interact with intelligent services. However, it is
unclear how to design effective XAI experiences for AR. We propose XAIR, a
design framework that addresses "when", "what", and "how" to provide
explanations of AI output in AR. The framework was based on a
multi-disciplinary literature review of XAI and HCI research, a large-scale
survey probing 500+ end-users' preferences for AR-based explanations, and three
workshops with 12 experts collecting their insights about XAI design in AR.
XAIR's utility and effectiveness was verified via a study with 10 designers and
another study with 12 end-users. XAIR can provide guidelines for designers,
inspiring them to identify new design opportunities and achieve effective XAI
designs in AR.Comment: Proceedings of the 2023 CHI Conference on Human Factors in Computing
System
The Semantic Reader Project: Augmenting Scholarly Documents through AI-Powered Interactive Reading Interfaces
Scholarly publications are key to the transfer of knowledge from scholars to
others. However, research papers are information-dense, and as the volume of
the scientific literature grows, the need for new technology to support the
reading process grows. In contrast to the process of finding papers, which has
been transformed by Internet technology, the experience of reading research
papers has changed little in decades. The PDF format for sharing research
papers is widely used due to its portability, but it has significant downsides
including: static content, poor accessibility for low-vision readers, and
difficulty reading on mobile devices. This paper explores the question "Can
recent advances in AI and HCI power intelligent, interactive, and accessible
reading interfaces -- even for legacy PDFs?" We describe the Semantic Reader
Project, a collaborative effort across multiple institutions to explore
automatic creation of dynamic reading interfaces for research papers. Through
this project, we've developed ten research prototype interfaces and conducted
usability studies with more than 300 participants and real-world users showing
improved reading experiences for scholars. We've also released a production
reading interface for research papers that will incorporate the best features
as they mature. We structure this paper around challenges scholars and the
public face when reading research papers -- Discovery, Efficiency,
Comprehension, Synthesis, and Accessibility -- and present an overview of our
progress and remaining open challenges
Phylogeny and Historical Biogeography of Asian Pterourus Butterflies (Lepidoptera: Papilionidae): A Case of Intercontinental Dispersal from North America to East Asia
The phylogenetic status of the well-known Asian butterflies often known as Agehana (a species group, often treated as a genus or a subgenus, within Papilio sensu lato) has long
remained unresolved. Only two species are included, and one of them especially, Papilio
maraho, is not only rare but near-threatened, being monophagous on its vulnerable hostplant, Sassafras randaiense (Lauraceae). Although the natural history and population conservation of âAgehanaâ has received much attention, the biogeographic origin of this group
still remains enigmatic. To clarify these two questions, a total of 86 species representatives
within Papilionidae were sampled, and four genes (concatenated length 3842 bp) were
used to reconstruct their phylogenetic relationships and historical scenarios. Surprisingly,
âAgehanaâ fell within the American Papilio subgenus Pterourus and not as previously suggested, phylogenetically close to the Asian Papilio subgenus Chilasa. We therefore formally
synonymize Agehana with Pterourus. Dating and biogeographic analysis allow us to infer
an intercontinental dispersal of an American ancestor of Asian Pterourus in the early Miocene, which was coincident with historical paleo-land bridge connections, resulting in the
present âEast Asia-Americaâ disjunction distribution. We emphasize that species exchange
between East Asia and America seems to be a quite frequent occurrence in butterflies during the Oligocene to Miocene climatic optima.Š 2015 Wu et al. This is an open access
article distributed under the terms of the Creative
Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are
credited
Integrated Analyses of Copy Number Variations and Gene Expression in Lung Adenocarcinoma
Numerous efforts have been made to elucidate the etiology and improve the treatment of lung cancer, but the overall five-year survival rate is still only 15%. Identification of prognostic biomarkers for lung cancer using gene expression microarrays poses a major challenge in that very few overlapping genes have been reported among different studies. To address this issue, we have performed concurrent genome-wide analyses of copy number variation and gene expression to identify genes reproducibly associated with tumorigenesis and survival in non-smoking female lung adenocarcinoma. The genomic landscape of frequent copy number variable regions (CNVRs) in at least 30% of samples was revealed, and their aberration patterns were highly similar to several studies reported previously. Further statistical analysis for genes located in the CNVRs identified 475 genes differentially expressed between tumor and normal tissues (p<10â5). We demonstrated the reproducibility of these genes in another lung cancer study (pâ=â0.0034, Fisher's exact test), and showed the concordance between copy number variations and gene expression changes by elevated Pearson correlation coefficients. Pathway analysis revealed two major dysregulated functions in lung tumorigenesis: survival regulation via AKT signaling and cytoskeleton reorganization. Further validation of these enriched pathways using three independent cohorts demonstrated effective prediction of survival. In conclusion, by integrating gene expression profiles and copy number variations, we identified genes/pathways that may serve as prognostic biomarkers for lung tumorigenesis
Safe approaches for camptothecin delivery: Structural analogues and nanomedicines
[EN] Twenty-(S)-camptothecin is a strongly cytotoxic molecule with excellent antitumor activity over a wide spectrum of human cancers. However, the direct formulation is limited by its poor water solubility, low plasmatic stability and severe toxicity, which currently limits its clinical use. As a consequence, two strategies have been developed in order to achieve safe and efficient delivery of camptothecin to target cells: structural analogues and nanomedicines. In this review, we summarize recent advances in the design, synthesis and development of camptothecin molecular derivatives and supramolecular vehicles, following a systematic classification according to structure-activity relationships (structural analogues) or chemical nature (nanomedicines). A series of organic, inorganic and hybrid materials are presented as nanoplatforms to overcome camptothecin restrictions in administration, biodistribution, pharmacokinetics and toxicity. Nanocarriers which respond to a variety of stimuli endogenously (e.g., pH, redox potential, enzyme activity) or exogenously (e.g., magnetic field, light, temperature, ultrasound) seem the best positioned therapeutic materials for optimal spatial and temporal control over drug release. The main goal of this review is to be used as a source of relevant literature for others interested in the field of camptothecin-based therapeutics. To this end, final remarks on the most important formulations currently under clinical trial are provided. (C) 2016 Elsevier B.V. All rights reserved.Financial support of the Spanish Ministry of Economy and Competitiveness (projects MAT2012-39290-C02-02 and SEV-2012-0267) is gratefully acknowledged. Dr. E.M. Rivero thanks the Cursol Foundation for a post-doctoral scholarship.Botella Asuncion, P.; Rivero-Buceta, EM. (2017). Safe approaches for camptothecin delivery: Structural analogues and nanomedicines. Journal of Controlled Release. 247:28-54. https://doi.org/10.1016/j.jconrel.2016.12.023S285424
iTRAQ Identification of Candidate Serum Biomarkers Associated with Metastatic Progression of Human Prostate Cancer
A major challenge in the management of patients with prostate cancer is identifying those individuals at risk of developing metastatic disease, as in most cases the disease will remain indolent. We analyzed pooled serum samples from 4 groups of patients (nâ=â5 samples/group), collected prospectively and actively monitored for a minimum of 5 yrs. Patients groups were (i) histological diagnosis of benign prostatic hyperplasia with no evidence of cancer âBPHâ, (ii) localised cancer with no evidence of progression, ânon-progressingâ (iii) localised cancer with evidence of biochemical progression, âprogressingâ, and (iv) bone metastasis at presentation âmetastaticâ. Pooled samples were immuno-depleted of the 14 most highly abundant proteins and analysed using a 4-plex iTRAQ approach. Overall 122 proteins were identified and relatively quantified. Comparisons of progressing versus non-progressing groups identified the significant differential expression of 25 proteins (p<0.001). Comparisons of metastatic versus progressing groups identified the significant differential expression of 23 proteins. Mapping the differentially expressed proteins onto the prostate cancer progression pathway revealed the dysregulated expression of individual proteins, pairs of proteins and âpanelsâ of proteins to be associated with particular stages of disease development and progression. The median immunostaining intensity of eukaryotic translation elongation factor 1 alpha 1 (eEF1A1), one of the candidates identified, was significantly higher in osteoblasts in close proximity to metastatic tumour cells compared with osteoblasts in control bone (pâ=â0.0353, Mann Whitney U). Our proteomic approach has identified leads for potentially useful serum biomarkers associated with the metastatic progression of prostate cancer. The panels identified, including eEF1A1 warrant further investigation and validation
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