32 research outputs found
Unbiased Supervised Contrastive Learning
Many datasets are biased, namely they contain easy-to-learn features that are
highly correlated with the target class only in the dataset but not in the true
underlying distribution of the data. For this reason, learning unbiased models
from biased data has become a very relevant research topic in the last years.
In this work, we tackle the problem of learning representations that are robust
to biases. We first present a margin-based theoretical framework that allows us
to clarify why recent contrastive losses (InfoNCE, SupCon, etc.) can fail when
dealing with biased data. Based on that, we derive a novel formulation of the
supervised contrastive loss (epsilon-SupInfoNCE), providing more accurate
control of the minimal distance between positive and negative samples.
Furthermore, thanks to our theoretical framework, we also propose FairKL, a new
debiasing regularization loss, that works well even with extremely biased data.
We validate the proposed losses on standard vision datasets including CIFAR10,
CIFAR100, and ImageNet, and we assess the debiasing capability of FairKL with
epsilon-SupInfoNCE, reaching state-of-the-art performance on a number of biased
datasets, including real instances of biases in the wild.Comment: Accepted at ICLR 202
Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy
IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical
attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced
colorectal cancers at diagnosis.
OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced
oncologic stage and change in clinical presentation for patients with colorectal cancer.
DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all
17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December
31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period),
in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was
30 days from surgery.
EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery,
palliative procedures, and atypical or segmental resections.
MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer
at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as
cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding,
lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery,
and palliative surgery. The independent association between the pandemic period and the outcomes
was assessed using multivariate random-effects logistic regression, with hospital as the cluster
variable.
RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years)
underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142
(56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was
significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR],
1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic
lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03).
CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the
SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients
undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for
these patients
Large deformation cyclic tests on stainless steel reinforcing bars for reinforced concrete structures in seismic regions
Experimental tests on strain rate dependance of mechanical characteristics of stainless steel bars for seismic resistant reinforced concrete structures
First evidence of Holocene activity and surface diplacement of the Budoia-Aviano Thrust System in north-eastern Italy, unravelled through the integration of geological, geophysic and paleoseismological analyses
We present the findings of a multimethodological study made on the Budoia-Aviano Thrust System conducted as part of the NASA4SHA PRIN Project “Fault segmentation and seismotectonics
of active thrust systems: the Northern Apennines and Southern Alps laboratories for new Seismic Hazard Assessments in northern Italy