Compression of EEG data.
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Electroencephalography↗
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Results for “Data Compression”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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Computerised method for acquisition and display of gastrointestinal motility data.
A computerised system is developed for the acquisition and display of gastrointestinal motility data which utilises a purpose developed software program called 'PC-motil', running on an IBM compatible microcomputer. 'PC-motil' displays data during collection, writes data to disk file and compresses all data at the end of a study on to a single monitor screen for convenient overview. Any area of interest, in single or multiple channels, may be selected and expanded for detailed examination. This system is tested by the recording of gastric and jejunal motility patterns of 11 healthy volunteers in fasting and fed states. All antral and jejunal migrating motor complexes (MMCs) in fasting studies, as well as all fed motility patterns were recognisable in both 'compressed' and 'expanded' form. The reproduction of motility patterns by the computer based system was indistinguishable from that of a conventional analogue chart recorder. This computerised system provides a convenient and cost-effective means of acquisition, storage and display of motility data in digital form.
Adult↗
The effect of mechanical deformation on the movement of water in foods.
This study has shown the importance of relating NMR spectroscopic information on the water in model food structures to the mechanical properties of those structures. Analysis of the NMR relaxation data can be used to examine the distribution of water domain sizes, and this has been related to the mechanical properties of the samples. A novel NMR probe-head has been designed, which allows both the NMR and the mechanical data to be simultaneously measured during compression of the sample. This probe-head allows compressive stress/strain data to be obtained directly from the NMR sample, allowing changes in the distribution of the water to be directly correlated to changes in mechanical properties.
Chemical Phenomena↗
Recurrent deep venous thrombosis: limitations of US.
Compression ultrasound (US) has become widely used to diagnose acute deep venous thrombosis (DVT). To determine the appearance of veins with previous DVT, 60 legs (58 patients) in which DVT had been diagnosed 6-31 months earlier (mean, 15.1 months) were reexamined with compression US. At reevaluation there was no indication of acute DVT. Thirty-two extremities had an appearance consistent with clot at the time of this study; 28 demonstrated normal findings. Variables that correlated with findings at follow-up US included age, location of clot, number of previous clots, pain, and augmentation of flow at compression. These preliminary data indicate that compression US may not be reliable as a follow-up study in patients in whom postphlebotic syndrome develops after an acute episode of DVT.
Follow-Up Studies↗
An efficient algorithm for MR image reconstruction and compression.
In magnetic resonance imaging (MRI), the original data are sampled in the spatial frequency domain. The sampled data thus constitute a set of discrete Fourier transform (DFT) coefficients. The image is usually reconstructed by taking inverse DFT. The image data may then be efficiently compressed using the discrete cosine transform (DCT). We present here a method of using DCT to treat the sampled data, which combines two procedures, image reconstruction and data compression. This method may be particularly useful in medical picture archiving and communication systems (PACS) where both image reconstruction and compression are important issues.
Algorithms↗
Enhancement and compression of digital chest radiographs.
The application of digital technologies to chest radiography holds the promise of routine application of image processing techniques to effect image enhancement. Because of their inherent spatial resolution, however, digital chest images impose severe constraints on data storage devices. Compression of these images will relax such constraints and facilitate image transmission on a digital network. We evaluated an algorithm for enhancing digital chest images that has allowed significant data compression while improving the diagnostic quality of the image. This algorithm is based on the photographic technique of unsharp masking. Image quality was measured with respect to the task of tumor detection and compression ratios as high as 2:1 were achieved. This compression can be supplemented by irreversible methods.
Algorithms↗
The compression of medical ultrasonic data.
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Humans↗
[The nasopharynx in jaw compression--craniometric and rhinologic data].
113 patients-7 to 29 years old-of the orthodontic department of the School of Dentistry, University of Minnesota, were studied. 51 patients had a high SN-MP angle (a long face) and 62 a low SN-MP angle (a broad face). As compared to the broad-faced group the probands with a long face showed, on the average, a narrower palatal arch, a more posteriorly postitioned hard palate, a smaller nasopharynx (measured in the sagittal plane), and more frequent nasopharyngeal problems. According to our statistical evaluation, a narrower maxillary dental arch and clinical apparent adenoid hypertrophy do not appear to be connected to each other in a cause-and-effect relationship. They rather seem to be two independent symptoms found frequently, though not necessarily in combination with each other, in persons with a long face.
Adolescent↗
Compression of Holter ECG data.
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Algorithms↗
Compression and reconstruction of MRI images using 2D DCT.
In magnetic resonance imaging (MRI), the original data are sampled in the spatial frequency domain. The sampled data thus constitute a set of discrete Fourier transform (DFT) coefficients. The image is usually reconstructed by taking inverse DFT. The image data may then be compressed using the discrete cosine transform (DCT). We present here a method of treating the data that combines two procedures, image reconstruction and data compression. This method may be particularly useful in medical picture archiving and communication systems (PACS) where both image reconstruction and compression are important issues.
Fourier Analysis↗
On the use of statistics for representing the knowledge acquired from experts in a medical consulting system.
For making medical consulting systems, it is important and significant to select and devise the method for representing the knowledge acquired from professional experts. As quantities of data required for consultation are increasing according to the progress of medical science, we have to introduce some new kinds of statistics into a medical consultation system. From another point of view, since the process of diagnosis of experts is considered to be a kind of effective model for compressing (or condensing) data quantitatively and qualitatively, we discuss the use of statistics for representing the knowledge acquired from experts from the standpoint of data compression.
Adult↗
Compression of nucleic acid and protein sequence data.
This paper describes the application of text compression methods to machine-readable files of nucleic acid and protein sequence data. Two main methods are used to reduce the storage requirements of such files, these being n-gram coding and run-length coding. A Pascal program combining both of these techniques resulted in a compression figure of 74.6% for the GenBank data-base and a program that used only n-gram coding gave a compression figure of 42.8% for the Protein Identification Resource database.
Algorithms↗
RSHash: a fast and space-efficient hash table for k-mers.
SUMMARY: Large genomic data collections can be viewed as a continuous string of DNA characters. The essential operations for data structures indexing the k-mer content of such a string are lookup and locate. Lookup determines whether a query k-mer q exists in the string and locate returns all locations in the string where q is present. High-throughput DNA sequencing generates very many k-mer sets of size exceeding billions of characters. In such scenarios, memory consumption and query efficiency pose significant challenges to a data structure supporting the above mentioned queries. To address this problem, we describe a simple, compressed, static data structure for k-mers that answers lookup and can be extended for supporting locate. The general scheme follows the use of minimizers like the state-of-the art SSHash. However, instead of using minimum perfect hash functions our solution (RSHash for Rank-Select Hash) relies on bitvectors with rank and select support, a multiple layered minimizer scheme, and a clever buffering strategy. We can show that RSHash is on average 40% and in some cases up to two times faster than SSHash while having the same memory requirements. Indeed we can go as low as 8 bits per canonical 31-mer on a human dataset. AVAILABILITY: https://github.com/jonsmcode/rshash.
Sequence Analysis, DNA↗
[Simplification of gamma-ray spectral data by using Fourier transform].
A method is proposed to represent gamma-ray response spectra by Fourier series for the purpose of compressing spectral data. The usefulness of the method was confirmed by applying it to a spectral library of a NaI detector. In the method, a response spectrum as a wave is described by superposition of sine (cosine) waves with low frequencies, whose coefficient parameters can be obtained by a Fast Fourier Transform program. The relation between the number of parameters and the fitting error is discussed, and as the result, it is shown that the number of parameters can be reduced to about a half. The merits and features are presented in practical application of the method to the analysis of gamma-ray spectra.
Fourier Analysis↗
Effect of fitting adjustments on compressive strength of a new foil crown system.
The effect of die spacing and precementation internal adjustments on the compressive strength of a new ceramic foil crown system was examined in vitro. Twenty-four ceramic foil crowns were made for identical stylized master dies made of polycarbonate filled with 30 wt% carbon. One half of the stone working dies were coated with die spacer and the remaining were left untreated. A special foil used for these crowns was adapted to the working dies under 2500 psi loading. A sculpturing device was used to standardize the size and shape of the ceramic foil crowns. Only crowns made on dies coated with die spacer received precementation fitting adjustment. All crowns in the two groups were cemented with zinc phosphate cement and were subjected to compressive force until fracture occurred. Compressive strength data were analyzed and compared. Results showed that the use of die spacer and internal adjustments increased the compressive strength of the new ceramic foil crown.
Crowns↗
Trends in future urodynamics: computer support-data base-digitized imaging.
The use of computers in urodynamics must be based preferably on the structure of the urodynamic investigation itself. This enables implementation of computerized systems in the urodynamic laboratory in the most natural way and provides transparency of urodynamic software for the investigators. Additionally, the algorithms of the urodynamic software then can provide for a urodynamic investigation following a logical path based on the patient's history and clinical data and (automatically interpreted) results from earlier steps in the urodynamics. As an extension of this structured logical reasoning, the computer use in urodynamics can be extended to include validation and decision rules, comprising measurement data and rules for interpretation and combination of history, clinical and measurement data. Conclusions will be presented then in the form of a preliminary differential diagnosis, including the odds for each of the possible diagnoses. These kinds of computerized interpretation systems will be validated by comparison with the classical clinical diagnoses and are generally known as expert systems. These systems rely on logical branching-as opposed to systems that are statistical in nature and use large data bases to classify individual data into known groups. Data bases will remain for the purpose of documentation, based on individual patients and comprising all patient data-comparable to the existing patient files in the hospital's archives. The computer files have to include also the original data from functional studies like urodynamics-and not just the abstracted conclusions-and from imaging techniques. Intelligent compression of data prevents the data bases from exploding. Digital imaging techniques combined with computerized urodynamic investigations open possibilities for dynamic analysis of morphologic data and combination thereof with urodynamic measurement data.
Databases, Factual↗
Saccular aneurysm of the transverse thoracic aorta detected by transesophageal echocardiography.
A patient with a saccular aneurysm of the thoracic aortic arch presented with severe right ventricular failure due to pulmonary artery compression. Contradictory data were derived from computed tomography, pulmonary isotope perfusion scan and cardiac catheterization. Transesophageal echocardiography revealed a saccular aneurysm which compressed the main pulmonary artery and gave access to a fistulous connection to the left pulmonary artery. Surgery confirmed these findings.
Aorta, Thoracic↗
Measurements of bone strain in foals with altered foot balance.
Two to 7 days after birth, 9 foals were anesthetized, and strain gauges were applied to lateral and medial aspects of the third metacarpal bone of the left forelimb. In 5 of these foals, strain gauges also were applied to the radius of the left forelimb. Four to 6 days later, foals were walked (5 sets of 10 to 20 strides), and compressive and tensile strains in the bone beneath strain gauges were recorded on paper and diskette. After recording base-line data, a wedge was fitted to the hoof of the limb with the strain gauges, in such a way that the lateral bearing surface was raised, and strains were recorded again. The wedge was left in place, and further recordings were made every 2 to 3 days for 10 days. At the normal walk (base-line data), the compressive strain was higher than the tensile strain in the third metacarpal bone, on the medial side of which the mean principal compressive strain was approximately twice that on the lateral surface. Immediately after application of the wedge, strain values from the medial surface of the third metacarpal bone decreased by 40%, and the lateral surface compressive strain increased by 100%. These changes gradually decreased over 10 days, at which time there was no significant difference from base-line values (P less than 0.05). Similar but much less obvious trends were observed in the radius. Abnormal hoof balance apparently had no lasting effect on compressive forces running through the limb, and the natural situation of higher compressive strain medially was restored quickly.
Animals↗