63 research outputs found
Imbalanced Gradients: A Subtle Cause of Overestimated Adversarial Robustness
Evaluating the robustness of a defense model is a challenging task in
adversarial robustness research. Obfuscated gradients, a type of gradient
masking, have previously been found to exist in many defense methods and cause
a false signal of robustness. In this paper, we identify a more subtle
situation called Imbalanced Gradients that can also cause overestimated
adversarial robustness. The phenomenon of imbalanced gradients occurs when the
gradient of one term of the margin loss dominates and pushes the attack towards
to a suboptimal direction. To exploit imbalanced gradients, we formulate a
Margin Decomposition (MD) attack that decomposes a margin loss into individual
terms and then explores the attackability of these terms separately via a
two-stage process. We also propose a MultiTargeted and an ensemble version of
our MD attack. By investigating 17 defense models proposed since 2018, we find
that 6 models are susceptible to imbalanced gradients and our MD attack can
decrease their robustness evaluated by the best baseline standalone attack by
another 2%. We also provide an in-depth analysis of the likely causes of
imbalanced gradients and effective countermeasures.Comment: 19 pages, 7 figue
Eureka: Human-Level Reward Design via Coding Large Language Models
Large Language Models (LLMs) have excelled as high-level semantic planners
for sequential decision-making tasks. However, harnessing them to learn complex
low-level manipulation tasks, such as dexterous pen spinning, remains an open
problem. We bridge this fundamental gap and present Eureka, a human-level
reward design algorithm powered by LLMs. Eureka exploits the remarkable
zero-shot generation, code-writing, and in-context improvement capabilities of
state-of-the-art LLMs, such as GPT-4, to perform evolutionary optimization over
reward code. The resulting rewards can then be used to acquire complex skills
via reinforcement learning. Without any task-specific prompting or pre-defined
reward templates, Eureka generates reward functions that outperform expert
human-engineered rewards. In a diverse suite of 29 open-source RL environments
that include 10 distinct robot morphologies, Eureka outperforms human experts
on 83% of the tasks, leading to an average normalized improvement of 52%. The
generality of Eureka also enables a new gradient-free in-context learning
approach to reinforcement learning from human feedback (RLHF), readily
incorporating human inputs to improve the quality and the safety of the
generated rewards without model updating. Finally, using Eureka rewards in a
curriculum learning setting, we demonstrate for the first time, a simulated
Shadow Hand capable of performing pen spinning tricks, adeptly manipulating a
pen in circles at rapid speed.Comment: Project website and open-source code:
https://eureka-research.github.io
Re-ViLM: Retrieval-Augmented Visual Language Model for Zero and Few-Shot Image Captioning
Augmenting pretrained language models (LMs) with a vision encoder (e.g.,
Flamingo) has obtained the state-of-the-art results in image-to-text
generation. However, these models store all the knowledge within their
parameters, thus often requiring enormous model parameters to model the
abundant visual concepts and very rich textual descriptions. Additionally, they
are inefficient in incorporating new data, requiring a computational-expensive
fine-tuning process. In this work, we introduce a Retrieval-augmented Visual
Language Model, Re-ViLM, built upon the Flamingo, that supports retrieving the
relevant knowledge from the external database for zero and in-context few-shot
image-to-text generations. By storing certain knowledge explicitly in the
external database, our approach reduces the number of model parameters and can
easily accommodate new data during evaluation by simply updating the database.
We also construct an interleaved image and text data that facilitates
in-context few-shot learning capabilities. We demonstrate that Re-ViLM
significantly boosts performance for image-to-text generation tasks, especially
for zero-shot and few-shot generation in out-of-domain settings with 4 times
less parameters compared with baseline methods.Comment: Findings of EMNLP 202
Overexpressed transferrin receptor implied poor prognosis and relapse in gastrointestinal stromal tumors
Ferroptosis, as a novel-induced programmed cell death, plays critical roles in the pathogenesis of cancers. However, the promising biomarkers of ferroptosis in gastrointestinal stromal tumor (GIST) remain to be elucidated. Herein, the expression of ferroptosis-related genes was analyzed in GIST. Among the 64 ferroptosis-related genes, transferrin receptor (TFRC) expression presented a remarkable upregulation in high-risk patients through Gene Expression Omnibus (GEO) dataset analysis, as well as its significant change after imatinib was treated. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of TFRC-relevant genes revealed that TFRC expression was closely associated with cell growth pathways and metabolism-related pathways. Furthermore, patients at high risk of recurrence were more likely to exhibit high TFRC expression by immunohistochemistry. Additionally, high TFRC expression indicated an undesirable state of patient relapse, which could serve as a powerful significant independent predictor of recurrence-free survival (RFS). In summary, we systematically summarize the expression characteristics and clinical relevance of TFRC and show that TFRC can be used as a prognostic factor, which can be considered a potential therapeutic target in GIST
Reticulation is a Risk Factor of Progressive Subpleural non-Fibrotic Interstitial Lung Abnormalities
Rationale: Interstitial lung abnormalities (ILAs) are being increasingly identified in clinical
practice. In particular for subpleural non-fibrotic ILAs, the risk of progression over time and
the risk factors for progressive behavior are still largely unknown.
Objectives: To determine the age band prevalence of ILAs and the risk of radiological
progression of subpleural non-fibrotic ILAs over time in a large health check-up population,
and to identify how reticulation contributes to the risk of radiological progression.
Methods: Based on ILAs definition by the Fleischner Society, low-dose chest CT images from
community-dwelling population undergone health check-up were evaluated for ILAs.
Multivariable logistic regression was used to assess the risk of radiological progression.
Measurements and Main Results: Among 155,539 individuals, 3,300 (2.1%) were confirmed
to have ILAs: the vast majority (81.7%) were defined as subpleural non-fibrotic ILAs. The
prevalence of ILAs increased linearly with age (P for trend<0.0001). Of 454 individuals with
subpleural non-fibrotic ILAs, 198 (43.6%) had radiological progression over 4 years. The
presence of reticulation on initial imaging was an independent predictor of radiological
progression (OR 1.9; 95%CI 1.2-3.0, P=0.0040). No difference in radiological progression was
identified between subpleural non-fibrotic ILAs with extensive reticulation and subpleural
fibrotic ILAs (73.0% vs. 68.8%, P=0.7626).
Conclusions: The prevalence of ILAs increases linearly with age. Nearly half of subpleural
non-fibrotic ILAs progress radiologically over 4 years. The presence of reticulation is a risk
factor for radiological progression. Subpleural non-fibrotic ILAs with extensive reticulation
are likely to be a feature of subpleural fibrotic ILAs
Metoclopramide or domperidone improves post-pyloric placement of spiral nasojejunal tubes in critically ill patients: a prospective, multicenter, open-label, randomized, controlled clinical trial
Epac1 mediates protein kinase A–independent mechanism of forskolin-activated intestinal chloride secretion
Intestinal Cl− secretion is stimulated by cyclic AMP (cAMP) and intracellular calcium ([Ca2+]i). Recent studies show that protein kinase A (PKA) and the exchange protein directly activated by cAMP (Epac) are downstream targets of cAMP. Therefore, we tested whether both PKA and Epac are involved in forskolin (FSK)/cAMP-stimulated Cl− secretion. Human intestinal T84 cells and mouse small intestine were used for short circuit current (Isc) measurement in response to agonist-stimulated Cl− secretion. FSK-stimulated Cl− secretion was completely inhibited by the additive effects of the PKA inhibitor, H89 (1 µM), and the [Ca2+]i chelator, 1,2-bis-(o-aminophenoxy)-ethane-N,N,N’,N’-tetraacetic acid, tetraacetoxymethyl ester (BAPTA-AM; 25 µM). Both FSK and the Epac activator 8-pCPT-2’-O-Me-cAMP (50 µM) elevated [Ca2+]i, activated Ras-related protein 2, and induced Cl− secretion in intact or basolateral membrane–permeabilized T84 cells and mouse ileal sheets. The effects of 8-pCPT-2’-O-Me-cAMP were completely abolished by BAPTA-AM, but not by H89. In contrast, T84 cells with silenced Epac1 had a reduced Isc response to FSK, and this response was completely inhibited by H89, but not by the phospholipase C inhibitor U73122 or BAPTA-AM. The stimulatory effect of 8-pCPT-2’-O-Me-cAMP on Cl− secretion was not abolished by cystic fibrosis transmembrane conductance (CFTR) inhibitor 172 or glibenclamide, suggesting that CFTR channels are not involved. This was confirmed by lack of effect of 8-pCPT-2’-O-Me-cAMP on whole cell patch clamp recordings of CFTR currents in Chinese hamster ovary cells transiently expressing the human CFTR channel. Furthermore, biophysical characterization of the Epac1-dependent Cl− conductance of T84 cells mounted in Ussing chambers suggested that this conductance was hyperpolarization activated, inwardly rectifying, and displayed a Cl−>Br−>I− permeability sequence. These results led us to conclude that the Epac-Rap-PLC-[Ca2+]i signaling pathway is involved in cAMP-stimulated Cl− secretion, which is carried by a novel, previously undescribed Cl− channel
Actively implementing an evidence-based feeding guideline for critically ill patients (NEED): a multicenter, cluster-randomized, controlled trial
Background: Previous cluster-randomized controlled trials evaluating the impact of implementing evidence-based guidelines for nutrition therapy in critical illness do not consistently demonstrate patient benefits. A large-scale, sufficiently powered study is therefore warranted to ascertain the effects of guideline implementation on patient-centered outcomes.
Methods: We conducted a multicenter, cluster-randomized, parallel-controlled trial in intensive care units (ICUs) across China. We developed an evidence-based feeding guideline. ICUs randomly allocated to the guideline group formed a local "intervention team", which actively implemented the guideline using standardized educational materials, a graphical feeding protocol, and live online education outreach meetings conducted by members of the study management committee. ICUs assigned to the control group remained unaware of the guideline content. All ICUs enrolled patients who were expected to stay in the ICU longer than seven days. The primary outcome was all-cause mortality within 28 days of enrollment.
Results: Forty-eight ICUs were randomized to the guideline group and 49 to the control group. From March 2018 to July 2019, the guideline ICUs enrolled 1399 patients, and the control ICUs enrolled 1373 patients. Implementation of the guideline resulted in significantly earlier EN initiation (1.20 vs. 1.55 mean days to initiation of EN; difference − 0.40 [95% CI − 0.71 to − 0.09]; P = 0.01) and delayed PN initiation (1.29 vs. 0.80 mean days to start of PN; difference 1.06 [95% CI 0.44 to 1.67]; P = 0.001). There was no significant difference in 28-day mortality (14.2% vs. 15.2%; difference − 1.6% [95% CI − 4.3% to 1.2%]; P = 0.42) between groups.
Conclusions: In this large-scale, multicenter trial, active implementation of an evidence-based feeding guideline reduced the time to commencement of EN and overall PN use but did not translate to a reduction in mortality from critical illness. Trial registration: ISRCTN, ISRCTN12233792. Registered November 20th, 2017
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