20 research outputs found
Compression of High-Resolution Satellite Images Using Optical Image Processing
This chapter presents a novel method for compressing satellite imagery using phase grating to facilitate the optimization of storage space and bandwidth in satellite communication. In this research work, each Satellite image is first modulated with high grating frequency in a fixed orientation. Due to this modulation, three spots (spectrum) have been generated. From these three spots, by applying Inverse Fourier Transform in any one band, we can recover the image. Out of these three spots, one is center spectrum spot and other spots represent two sidebands. Care should be taken during the spot selection is to avoid aliasing effect. At the receiving end, to recover image we use only one spectrum. We have proved that size of the extracted image is less than the original image. In this way, compression of satellite image has been performed. To measure quality of the output images, PSNR value has been calculated and compared this value with previous techniques. As high-resolution satellite image contains a lot of information, therefore to get detail information from extracted image, compression ratio should be as minimum as possible
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Predicting seizure recurrence after an initial seizure-like episode from routine clinical notes using large language models: A retrospective cohort study
Background: The evaluation and management of first-time seizure-like events in children can be difficult because these episodes are not always directly observed and might be epileptic seizures or other conditions (seizure mimics). We aimed to evaluate whether machine learning models using real-world data could predict seizure recurrence after an initial seizure-like event. Methods: This retrospective cohort study compared models trained and evaluated on two separate datasets between Jan 1, 2010, and Jan 1, 2020: electronic medical records (EMRs) at Boston Children's Hospital and de-identified, patient-level, administrative claims data from the IBM MarketScan research database. The study population comprised patients with an initial diagnosis of either epilepsy or convulsions before the age of 21 years, based on International Classification of Diseases, Clinical Modification (ICD-CM) codes. We compared machine learning-based predictive modelling using structured data (logistic regression and XGBoost) with emerging techniques in natural language processing by use of large language models. Findings: The primary cohort comprised 14 021 patients at Boston Children's Hospital matching inclusion criteria with an initial seizure-like event and the comparison cohort comprised 15 062 patients within the IBM MarketScan research database. Seizure recurrence based on a composite expert-derived definition occurred in 57% of patients at Boston Children's Hospital and 63% of patients within IBM MarketScan. Large language models with additional domain-specific and location-specific pre-training on patients excluded from the study (F1-score 0路826 [95% CI 0路817-0路835], AUC 0路897 [95% CI 0路875-0路913]) performed best. All large language models, including the base model without additional pre-training (F1-score 0路739 [95% CI 0路738-0路741], AUROC 0路846 [95% CI 0路826-0路861]) outperformed models trained with structured data. With structured data only, XGBoost outperformed logistic regression and XGBoost models trained with the Boston Children's Hospital EMR (logistic regression: F1-score 0路650 [95% CI 0路643-0路657], AUC 0路694 [95% CI 0路685-0路705], XGBoost: F1-score 0路679 [0路676-0路683], AUC 0路725 [0路717-0路734]) performed similarly to models trained on the IBM MarketScan database (logistic regression: F1-score 0路596 [0路590-0路601], AUC 0路670 [0路664-0路675], XGBoost: F1-score 0路678 [0路668-0路687], AUC 0路710 [0路703-0路714]). Interpretation: Physician's clinical notes about an initial seizure-like event include substantial signals for prediction of seizure recurrence, and additional domain-specific and location-specific pre-training can significantly improve the performance of clinical large language models, even for specialised cohorts.</p
Hierarchical class incremental learning of anatomical structures in fetal echocardiography videos
This paper proposes an ultrasound video
interpretation algorithm that enables novel classes or
instances to be added over time, without significantly
affecting prediction abilities on prior representations. The
motivating application is fetal echocardiography in midtrimester scans. In this application, a sonographer may
acquire multiple video clips of the heart at different points
in the full scan. The goal is to make a complete inference
of the health of the fetal heart from those multiple clips.
To address this scenario, we propose to use an
incremental learning approach to build a hierarchical
network model that allows for a parallel inclusion of
previously unseen anatomical classes without requiring
prior data distributions. Super classes are obtained by
coarse classification followed by fine classification to
allow the model to self-organize anatomical structures in a
sequence of categories through a modular architecture.
We show that this approach can be adapted with new
variable data distributions without significantly affecting
previously learned representations. Two extreme
situations of new data addition are considered; (1) new
class data is available over time with volume and
distribution similar to prior available classes, and (2)
imbalanced datasets arrive over future time to be learned
in a few-shot setting. In either case, availability of data
from prior classes is not assumed. Evolution of the
learning process is validated using incremental
accuracies of fine classification over novel classes and
compared to results from an end-to-end transfer learningderived model fine-tuned on a clinical dataset annotated
by experienced sonographers. The modularization of
subsequent learning reduces the depreciation in future
accuracies over old tasks from 6.75% to 1.10% using
balanced increments. The depreciation is reduced from
6.95% to 1.89% with imbalanced data distributions in
future increments, while retaining competitive
classification accuracies in new additions of fine classes
with parameter operations in the same order of magnitude
in all stages in both cases
Respondent-specific randomized response technique to estimate sensitive proportion
In estimating the proportion of people bearing a stigmatizing characteristic in a community of people, randomized response techniques are plentifully available in the literature. They are implemented essentially using boxes of similar cards of two distinguishable types. In this paper, we propose a more general procedure using five different types of cards. A respondent-specific randomized response technique is also proposed, in which respondents are allowed to build up the boxes according to their own choices. An immediate objective for this change is to enhance, sense of protection of privacy of the respondents. But as by-products, higher efficiency in terms of actual coverage percentages of confidence intervals and related features are demonstrated by a simulation study, and superior jeopardy levels against divulgence of personal secrecy are also reported to be achievable. AMS subject classification: 62D05
How privacy may be protected in optional randomized response surveys
There are materials in literature about how privacy on stigmatizing features like alcoholism, history of tax-evasion, or testing positive in AIDS-related testing may be partially protected by a proper application of randomized response techniques (RRT). The paper demonstrates what amendments are necessary for this approach while applying optional RRTs covering qualitative characteristics, permitting a sampled respondent either to directly reveal sensitive data or choose a randomized response respectively with complementary probabilities. Only a few standard RRTs are illustrated in the text