33 research outputs found
Likelihood-Based Text-to-Image Evaluation with Patch-Level Perceptual and Semantic Credit Assignment
Text-to-image synthesis has made encouraging progress and attracted lots of
public attention recently. However, popular evaluation metrics in this area,
like the Inception Score and Fr'echet Inception Distance, incur several issues.
First of all, they cannot explicitly assess the perceptual quality of generated
images and poorly reflect the semantic alignment of each text-image pair. Also,
they are inefficient and need to sample thousands of images to stabilise their
evaluation results. In this paper, we propose to evaluate text-to-image
generation performance by directly estimating the likelihood of the generated
images using a pre-trained likelihood-based text-to-image generative model,
i.e., a higher likelihood indicates better perceptual quality and better
text-image alignment. To prevent the likelihood of being dominated by the
non-crucial part of the generated image, we propose several new designs to
develop a credit assignment strategy based on the semantic and perceptual
significance of the image patches. In the experiments, we evaluate the proposed
metric on multiple popular text-to-image generation models and datasets in
accessing both the perceptual quality and the text-image alignment. Moreover,
it can successfully assess the generation ability of these models with as few
as a hundred samples, making it very efficient in practice
Recommended from our members
Neuroimaging Studies of Essential Tremor: How Well Do These Studies Support/Refute the Neurodegenerative Hypothesis?
Background: Tissueâbased research has recently led to a new pathoâmechanistic model of essential tremor (ET)âthe cerebellar degenerative model. We are not aware of a study that has reviewed the current neuroimaging evidence, focusing on whether the studies support or refute the neurodegenerative hypothesis of ET. This was our aim.
Methods: References for this review were identified by searches of PubMed (1966 to February 2014).
Results: Several neuroimaging methods have been used to study ET, most of them based on magnetic resonance imaging (MRI). The methods most specific to address the question of neurodegeneration are MRIâbased volumetry, magnetic resonance spectroscopy, and diffusionâweighted imaging. Studies using each of these methods provide support for the presence of cerebellar degeneration in ET, finding reduced cerebellar brain volumes, consistent decreases in cerebellar Nâacetylaspartate, and increased mean diffusivity. Other neuroimaging techniques, such as functional MRI and positron emission tomography (PET) are less specific, but still sensitive to potential neurodegeneration. These techniques are used for measuring a variety of brain functions and their impairment. Studies using these modalities also largely support cerebellar neuronal impairment. In particular, changes in 11Câflumazenil binding in PET studies and changes in iron deposition in an MRI study provide evidence along these lines. The composite data point to neuronal impairment and likely neuronal degeneration in ET.
Discussion: Recent years have seen a marked increase in the number of imaging studies of ET. As a whole, the combined data provide support for the presence of cerebellar neuronal degeneration in this disease
Reproducibility and effect of tissue composition on cerebellar GABA MRS in an elderly population.
Magnetic resonance spectroscopy (MRS) provides a valuable tool to non-invasively detect brain gamma-amino butyric acid (GABA) in vivo. GABAergic dysfunction has been observed in the aging cerebellum. Studying cerebellar GABA changes is of considerable interest in understanding certain age-related motor disorders. However, little is known about the reproducibility of GABA MRS in an aged population. Therefore, this study aimed to explore the feasibility and reproducibility of GABA MRS in the aged cerebellum at 3.0 Tesla and to examine the effect of differing tissue composition on GABA measurements. MRI and 1H MRS exams were performed on 10 healthy elderly volunteers (mean age 75.2 years ± 6.5 years) using a 3.0 Tesla Siemens Tim Trio scanner. Among them, 5 subjects were scanned twice to assess short-term reproducibility. The MEGA-PRESS J-editing sequence was used for GABA detection in two volumes of interest (VOIs) in left and right cerebellar dentate. MRS data processing and quantification were performed with LCModel 6.3-0L using two separate basis sets, generated from density matrix simulations using published values for chemical shifts an
Cingulate cortex hypoperfusion predicts Alzheimer's disease in mild cognitive impairment
BACKGROUND: Mild cognitive impairment (MCI) was recently described as a heterogeneous group with a variety of clinical outcomes and high risk to develop Alzheimer's disease (AD). Regional cerebral blood flow (rCBF) as measured by single photon emission computed tomography (SPECT) was used to study the heterogeneity of MCI and to look for predictors of future development of AD. METHODS: rCBF was investigated in 54 MCI subjects using Tc-99m hexamethylpropyleneamine oxime (HMPAO). An automated analysis software (BRASS) was applied to analyze the relative blood flow (cerebellar ratios) of 24 cortical regions. After the baseline examination, the subjects were followed clinically for an average of two years. 17 subjects progressed to Alzheimer's disease (PMCI) and 37 subjects remained stable (SMCI). The baseline SPECT ratio values were compared between PMCI and SMCI. Receiver operating characteristic (ROC) analysis was applied for the discrimination of the two subgroups at baseline. RESULTS: The conversion rate of MCI to AD was 13.7% per year. PMCI had a significantly decreased rCBF in the left posterior cingulate cortex, as compared to SMCI. Left posterior cingulate rCBF ratios were entered into a logistic regression model for ROC curve calculation. The area under the ROC curve was 74%â76%, which indicates an acceptable discrimination between PMCI and SMCI at baseline. CONCLUSION: A reduced relative blood flow of the posterior cingulate gyrus could be found at least two years before the patients met the clinical diagnostic criteria of AD
Mild cognitive impairment neuroimaging markers for early diagnosis of dementia
This thesis concerns the investigation of mild cognitive impairment (MCI)
and Alzheimer's disease (AD) using single photon emission computed
tomography (SPECT) and quantitative electroencepholography (qEEG).
In study I, The qEEG values were cross-sectionally compared between AD,
MCI and controls. AD had decreased global field power (GFP) and more
anterior localization of three-dimensional dipole source in alpha and
beta frequency. The results of longitudinal investigation of MCI showed a
decreased alpha GFP and a more anterior localization of sources of theta,
alpha and beta frequency in progressive mild cognitive impairment (PMCI),
as compared to non-progressive mild cognitive impairment (SMCI). EEG
values showed a moderate diagnostic accuracy in the study of AD and MCI.
In study II & III, the baseline regional cerebral blood flow (rCBF) and
neuropsychology were investigated in PMCI and SMCI. PMCI had decreased
regional cerebral blood flow (rCBF) in posterior cingulate and parietal
lobe as well as increased brain perfusion in prefrontal cortex compared
to SMCI at baseline. The cognitive functions of PMCI were lower than SMCI
with respect to episodic memory, visuospatial and general cognitive
function represented by Mini-Mental State Examination (MMSE). Both SPECT
and Neuropsychological test had moderate discriminant function between
PMCI and SMCI at baseline and combining two methods can improve the
diagnostic accuracy.
In study IV, the longitudinal rCBF changes of PMCI and SMCI were
investigated. SPECT data were analyzed with statistical parametric
mapping (SPM) and BRASS program. No significant findings were detected
using SPM. The results of BRASS showed a significant rCBF longitudinal
reduction of PMCI in superior parietal lobe, parieto-temporal association
cortex and medial temporal lobe and a significantly decreased general
cognitive function represented by MMSE.
To summarize, SPECT and EEG could provide promising markers for the early
diagnosis of dementia and track the disease progression. Combining
imaging investigation with neuropsychological testing may increase the
diagnostic accuracy of preclinical dementia
Optimizing the performance of operations-finance interface by implementing supply chain finance schemes
Individual-level precision diagnosis for coronavirus disease 2019 related severe outcome: an early study in New York
Abstract Because of inadequate information provided by the on-going population level risk analyses for Coronavirus disease 2019 (COVID-19), this study aimed to evaluate the risk factors and develop an individual-level precision diagnostic method for COVID-19 related severe outcome in New York State (NYS) to facilitate early intervention and predict resource needs for patients with COVID-19. We analyzed COVID-19 related hospital encounter and hospitalization in NYS using Statewide Planning and Research Cooperative System hospital discharge dataset. Logistic regression was performed to evaluate the risk factors for COVID-19 related mortality. We proposed an individual-level precision diagnostic method by taking into consideration of the different weights and interactions of multiple risk factors. Age was the greatest risk factor for COVID-19 related fatal outcome. By adding other demographic variables, dyspnea or hypoxemia and multiple chronic co-morbid conditions, the model predictive accuracy was improved to 0.85 (95% CI 0.84â0.85). We selected cut-off points for predictors and provided a general recommendation to categorize the levels of risk for COVID-19 related fatal outcome, which can facilitate the individual-level diagnosis and treatment, as well as medical resource prediction. We further provided a use case of our method to evaluate the feasibility of public health policy for monoclonal antibody therapy
A comparative F-dopa and FDG PET study of parkinsonian subjects without evidence of dopaminergic dysfunction
A Rice Receptor-like Protein Negatively Regulates Rice Resistance to Southern Rice Black-Streaked Dwarf Virus Infection
Plants rely on various receptor-like proteins and receptor-like kinases to recognize and defend against invading pathogens. However, research on the role of receptor-like proteins in plant antiviral defense, particularly in riceâvirus interactions, is limited. In this study, we identified a receptor-like gene, OsBAP1, which was significantly induced upon infection with southern rice black-streaked dwarf virus (SRBSDV) infection. A viral inoculation assay showed that the OsBAP1 knockout mutant exhibited enhanced resistance to SRBSDV infection, indicating that OsBAP1 plays a negatively regulated role in rice resistance to viral infection. Transcriptome analysis revealed that the genes involved in plantâpathogen interactions, plant hormone signal transduction, oxidationâreduction reactions, and protein phosphorylation pathways were significantly enriched in OsBAP1 mutant plants (osbap1-cas). Quantitative real-time PCR (RT-qPCR) analysis further demonstrated that some defense-related genes were significantly induced during SRBSDV infection in osbap1-cas mutants. Our findings provide new insights into the role of receptor-like proteins in plant immune signaling pathways, and demonstrate that OsBAP1 negatively regulates rice resistance to SRBSDV infection