322 research outputs found
Positivstellens\"atze and Moment problems with Universal Quantifiers
This paper studies Positivstellens\"atze and moment problems for sets that
are given by universal quantifiers. Let be a closed set and let be a tuple of polynomials in two vector variables and .
Then is described as the set of all points such that each for all . Fix a measure with , and assume
it satisfies the Carleman condition.
The first main result of the paper is a Positivstellensatz with universal
quantifiers: if a polynomial is positive on , then it belongs to the
quadratic module associated to , under the archimedeanness
assumption on . Here, denotes the quadratic module of
polynomials in that can be represented as where each is a sum of squares polynomial.
Second, necessary and sufficient conditions for a full (or truncated)
multisequence to admit a representing measure supported in are given. In
particular, the classical flat extension theorem of Curto and Fialkow is
generalized to truncated moment problems on such a set . Finally,
applications of these results for solving semi-infinite optimization problems
are presented
RADAR: Robust AI-Text Detection via Adversarial Learning
Recent advances in large language models (LLMs) and the intensifying
popularity of ChatGPT-like applications have blurred the boundary of
high-quality text generation between humans and machines. However, in addition
to the anticipated revolutionary changes to our technology and society, the
difficulty of distinguishing LLM-generated texts (AI-text) from human-generated
texts poses new challenges of misuse and fairness, such as fake content
generation, plagiarism, and false accusation of innocent writers. While
existing works show that current AI-text detectors are not robust to LLM-based
paraphrasing, this paper aims to bridge this gap by proposing a new framework
called RADAR, which jointly trains a Robust AI-text Detector via Adversarial
leaRning. RADAR is based on adversarial training of a paraphraser and a
detector. The paraphraser's goal is to generate realistic contents to evade
AI-text detection. RADAR uses the feedback from the detector to update the
paraphraser, and vice versa. Evaluated with 8 different LLMs (Pythia, Dolly
2.0, Palmyra, Camel, GPT-J, Dolly 1.0, LLaMA, and Vicuna) across 4 datasets,
experimental results show that RADAR significantly outperforms existing AI-text
detection methods, especially when paraphrasing is in place. We also identify
the strong transferability of RADAR from instruction-tuned LLMs to other LLMs,
and evaluate the improved capability of RADAR via GPT-3.5.Comment: Preprint. Project page and demos: https://radar.vizhub.a
A gene catalogue for post-diapause development of an anhydrobiotic arthropod Artemia franciscana
<p>Abstract</p> <p>Background</p> <p>Diapause is a reversible state of developmental suspension and found among diverse taxa, from plants to animals, including marsupials and some other mammals. Although previous work has accumulated ample data, the molecular mechanism underlying diapause and reactivation from it remain elusive.</p> <p>Results</p> <p>Using <it>Artemia franciscana</it>, a model organism to study the development of post-diapause embryos in Arthropod, we sequenced random clones up to a total of 28,039 ESTs from four cDNA libraries made from dehydrated cysts and three time points after rehydration/reactivation, which were assembled into 8,018 unigene clusters. We identified 324 differentially-expressed genes (DEGs, <it>P </it>< 0.05) based on pairwise comparisons of the four cDNA libraries. We identified a group of genes that are involved in an anti-water-deficit system, including proteases, protease inhibitors, heat shock proteins, and several novel members of the late embryogenesis abundant (LEA) protein family. In addition, we classified most of the up-regulated genes after cyst reactivation into metabolism, biosynthesis, transcription, and translation, and this result is consistent with the rapid development of the embryo. Some of the specific expressions of DEGs were confirmed experimentally based on quantitative real-time PCR.</p> <p>Conclusion</p> <p>We found that the first 5-hour period after rehydration is most important for embryonic reactivation of <it>Artemia</it>. As the total number of expressed genes increases significantly, the majority of DEGs were also identified in this period, including a group of water-deficient-induced genes. A group of genes with similar functions have been described in plant seeds; for instance, one of the novel LEA members shares ~70% amino-acid identity with an <it>Arabidopsis </it>EM (embryonic abundant) protein, the closest animal relative to plant LEA families identified thus far. Our findings also suggested that not only nutrition, but also mRNAs are produced and stored during cyst formation to support rapid development after reactivation.</p
GlycoPep MassList: Software to Generate Massive Inclusion Lists for Glycopeptide Analyses
Protein glycosylation drives many biological processes and serves as markers for disease; therefore, the development of tools to study glycosylation is an essential and growing area of research. Mass spectrometry can be used to identify both the glycans of interest and the glycosylation sites to which those glycans are attached, when proteins are proteolytically digested and their glycopeptides are analyzed by a combination of high-resolution mass spectrometry (MS) and tandem mass spectrometry (MS/MS) methods. One major challenge in these experiments is collecting the requisite MS/MS data. The digested glycopeptides are often present in complex mixtures and in low abundance, and the most commonly used approach to collect MS/MS data on these species is data-dependent acquisition (DDA), where only the most intense precursor ions trigger MS/MS. DDA results in limited glycopeptide coverage. Semi-targeted data acquisition is an alternative experimental approach that can alleviate this difficulty. However, due to the massive heterogeneity of glycopeptides, it is not obvious how to expediently generate inclusion lists for these types of analyses. To solve this problem, we developed the software tool GlycoPep MassList, which can be used to generate inclusion lists for liquid chromatography tandem-mass spectrometry (LC-MS/MS) experiments. The utility of the software was tested by conducting comparisons between semi-targeted and untargeted data-dependent analysis experiments on a variety of proteins, including IgG, a protein whose glycosylation must be characterized during its production as a biotherapeutic. When the GlycoPep MassList software was used to generate inclusion lists for LC-MS/MS experiments, more unique glycopeptides were selected for fragmentation. Generally, ā¼30 % more unique glycopeptides can be analyzed per protein, in the simplest cases, with low background. In cases where background ions from proteins or other interferents are high, usage of an inclusion list is even more advantageous. The software is freely publically accessible
Transcriptomic profiling of mature embryo from an elite super-hybrid rice LYP9 and its parental lines
<p>Abstract</p> <p>Background</p> <p>The mature embryo of rice (<it>Oryza sativa, L</it>.) is a synchronized and integrated tissue mass laying the foundation at molecular level for its growth, development, and differentiation toward a developing and ultimately a mature plant. We carried out an EST (expressed-sequence-tags)-based transcriptomic study, aiming at gaining molecular insights into embryonic development of a rice hybrid triadāan elite hybrid rice <it>LYP</it>9 and its parental lines (<it>93-11 </it>and <it>PA64s</it>)āand possible relatedness to heterosis.</p> <p>Results</p> <p>We generated 27,566 high-quality ESTs from cDNA libraries made from mature rice embryos. We classified these ESTs into 7,557 unigenes (2,511 contigs and 5,046 singletons) and 7,250 (95.9%) of them were annotated. We noticed that the high-abundance genes in mature rice embryos belong to two major functional categories, stress-tolerance and preparation-for-development, and we also identified 191 differentially-expressed genes (General Chi-squared test, <it>P</it>-value <= 0.05) between <it>LYP9 </it>and its parental lines, representing typical expression patterns including over-dominance, high- and low-parent dominance, additivity, and under-dominance. In <it>LYP9</it>, the majority of embryo-associated genes were found not only abundantly and specifically enriched but also significantly up-regulated.</p> <p>Conclusion</p> <p>Our results suggested that massively strengthening tissue-(or stage-) characteristic functions may contribute to heterosis rather than a few simple mechanistic explanations at the individual gene level. In addition, the large collection of rice embryonic ESTs provides significant amount of data for future comparative analyses on plant development, especially for the important crops of the grass family.</p
Fake science: The impact of pseudo-psychological demonstrations on peopleās beliefs in psychological principles
Magicians use deception to create effects that allow us to experience the impossible. More recently, magicians have started to contextualize these tricks in psychological demonstrations. We investigated whether witnessing a magic demonstration alters peopleās beliefs in these pseudo-psychological principles. In the classroom, a magician claimed to use psychological skills to read a volunteerās thoughts. After this demonstration, participants reported higher beliefs that an individual can 1) read a personās mind by evaluating micro expressions, psychological profiles and muscle activities, and 2) effectively prime a personās behaviour through subtle suggestions. Whether he was presented as a magician or psychologist did not influence peopleās beliefs about how the demonstration was achieved, nor did it influence their beliefs in pseudo-psychological principles. Our results demonstrate that pseudo-psychological demonstrations can have a significant impact on perpetuating false beliefs in scientific principles and raise important questions about the wider impact of scientific misinformation
Fabrication and Characterization of Collagen/PVA Dual-Layer Membranes for Periodontal Bone Regeneration
Guided tissue regeneration (GTR) is a promising treatment for periodontal tissue defects, which generally uses a membrane to build a mechanical barrier from the gingival epithelium and hold space for the periodontal regeneration especially the tooth-supporting bone. However, existing membranes possess insufficient mechanical properties and limited bioactivity for periodontal bone regenerate. Herein, fish collagen and polyvinyl alcohol (Col/PVA) dual-layer membrane were developed via a combined freezing/thawing and layer coating method. This dual-layer membrane had a clear but contact boundary line between collagen and PVA layers, which were both hydrophilic. The dual membrane had an elongation at break of 193 Ā± 27% and would undergo an in vitro degradation duration of more than 17 days. Further cell experiments showed that compared with the PVA layer, the collagen layer not only presented good cytocompatibility with rat bone marrow-derived mesenchymal stem cells (BMSCs), but also promoted the osteogenic genes (RUNX2, ALP, OCN, and COL1) and protein (ALP) expression of BMSCs. Hence, the currently developed dual-layer membranes could be used as a stable barrier with a stable degradation rate and selectively favor the bone tissue to repopulate the periodontal defect. The membranes could meet the challenges encountered by GTR for superior defect repair, demonstrating great potential in clinical applications
Towards Distribution-Agnostic Generalized Category Discovery
Data imbalance and open-ended distribution are two intrinsic characteristics
of the real visual world. Though encouraging progress has been made in tackling
each challenge separately, few works dedicated to combining them towards
real-world scenarios. While several previous works have focused on classifying
close-set samples and detecting open-set samples during testing, it's still
essential to be able to classify unknown subjects as human beings. In this
paper, we formally define a more realistic task as distribution-agnostic
generalized category discovery (DA-GCD): generating fine-grained predictions
for both close- and open-set classes in a long-tailed open-world setting. To
tackle the challenging problem, we propose a Self-Balanced Co-Advice
contrastive framework (BaCon), which consists of a contrastive-learning branch
and a pseudo-labeling branch, working collaboratively to provide interactive
supervision to resolve the DA-GCD task. In particular, the contrastive-learning
branch provides reliable distribution estimation to regularize the predictions
of the pseudo-labeling branch, which in turn guides contrastive learning
through self-balanced knowledge transfer and a proposed novel contrastive loss.
We compare BaCon with state-of-the-art methods from two closely related fields:
imbalanced semi-supervised learning and generalized category discovery. The
effectiveness of BaCon is demonstrated with superior performance over all
baselines and comprehensive analysis across various datasets. Our code is
publicly available.Comment: Accepted at NeurIPS 202
Tunable hysteresis effect for perovskite solar cells
Perovskite solar cells (PSCs) usually suffer from a hysteresis effect in currentāvoltage measurements,
which leads to an inaccurate estimation of the device e
fficiency. Although ion migration, charge trapping/
detrapping, and accumulation have been proposed as a b
asis for the hysteresis, the
origin of the hysteresis
has not been apparently unraveled. Herein we reporte
d a tunable hysteresis effect based uniquely on open-
circuit voltage variations in printable mesos
copic PSCs with a simplified triple-layer TiO
2
/ZrO
2
/carbon
architecture. The electrons are collected by the compact TiO
2
/mesoporous TiO
2
(c-TiO
2
/mp-TiO
2
)bilayer,
and the holes are collected by the carbon layer. By adj
usting the spray deposition cycles for the c-TiO
2
layer
andUV-ozonetreatment,weachievedhysteresis-norm
al, hysteresis-free, and hysteresis-inverted PSCs.
Such unique trends of tunable hysteresis are anal
yzed by considering the polarization of the TiO
2
/perovskite
interface, which can accumulate positive charges reversibly. Successfully tuning of the hysteresis effect
clarifies the critical importance of the c-TiO
2
/perovskite interface in controlling the hysteretic trends
observed, providing important insights towards the understanding of this rapidly developing photovoltaic
technology
Do Chinese Traditional and Modern Cultures Affect Young Adultsā Moral Priorities?
Dramatic cultural change has occurred in Mainland China over the past four decades, yet little is known about how this cultural shift impacts Chinese peoplesā moral values. The present research aims to fill this gap by examining whether Chinese traditional and modern cultures influence young adultsā moral judgments. Study 1 investigated the relation between psychological traditionality/modernity and moral concerns. Results indicated that participants who strongly endorsed Chinese traditional culture prioritize relationship concern rather than justice concern. Study 2 used the cultural priming method and tested the effects of traditional and modern icons on moral concerns. Results suggested that participants who were primed with traditional or modern or neutral icons did not give priority to relationship or justice concern. Together, our findings provide initial empirical evidence on whether Chinese traditional and modern cultures shift the moral mindsets of bicultural young Chinese among alternative (and even competing) moral codes
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