SEARCH · PubMed Health

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources

PubMed1991

Effect of moisture content on compression properties of two dextrose-based directly compressible diluents.

Moisture sorption characteristics and the effect of moisture content on the compression properties of two dextrose-based directly compressible diluents, namely, Emdex (diluent A) and Sweetrex (diluent B) were studied. Both diluents sorbed moisture rapidly at relative humidities greater than 60%. For both the diluents, pressures required to compress tablets to the same relative density decreased with increasing moisture content. Yield pressures calculated from linear Heckel plots obtained from the compression data of both diluents reflected decreasing values with increasing moisture content. Three-way surface profile graphs of moisture content versus tablet parameters such as crushing force, relative density, and compression pressure give a unique overall picture of the compression properties of a diluent and offer the tablet formulator a useful tool for diluent comparison.

Chemical Phenomena↗

PubMed2025

SKiM: accurately classifying metagenomic ONT reads in limited memory.

MOTIVATION: Oxford Nanopore Technologies' devices, such as MinION, permit affordable, real-time DNA sequencing, and come with targeted sequencing capabilities. Such capabilities create new challenges for metagenomic classifiers that must be computationally efficient yet robust enough to handle potentially erroneous DNA reads, while ideally inspecting only a few hundred bases of a read. Currently available DNA classifiers leave room for improvement with respect to classification accuracy, memory usage, and the ability to operate in targeted sequencing scenarios. RESULTS: We present SKiM: Short K-mers in Metagenomics, a new lightweight metagenomic classifier designed for ONT reads. Compared to state-of-the-art classifiers, SKiM requires only a fraction of memory to run, and can classify DNA reads with higher accuracy after inspecting only their first few hundred bases. To achieve this, SKiM introduces new data compression techniques to maintain a reference database built from short k-mers, and treats classification as a statistical testing problem. AVAILABILITY AND IMPLEMENTATION: SKiM source code, documentation, and test data are available from: https://gitlab.com/SCoRe-Group/skim.

Metagenomics↗

PubMedDate not supplied

Automated electrocardiogram analysis: the state of the art.

The overwhelming number of electrocardiograms (ECGs) now recorded routinely has prompted the development of computer analysis which in turn has benefited electrocardiography with important technological advances. All automated ECG analysis systems adopt a similar approach: a measurement program and a program that interprets the clinical significance of these measurements along with a rhythm analysis algorithm. Measurement, selection and classification of parameters vary according to the program used. Data compression is applied to the signal to reduce processing time and allow long-term storage. Diagnostic accuracy, however, is not greatly improved over that of experienced cardiologists. Programs studied using a validated data bank provided by an international group of cardiologists show a variability not only in parameter measurement but also in diagnostic statement and in the way in which such statements are expressed. Recommendations for measurement standards have been made to fulfil the need for exchange of diagnostic criteria. No recommendations concerning the selection of parameters have been proposed, and so new parameters or combinations of parameters can be introduced with the ultimate aim of increased diagnostic performance.

Diagnosis, Computer-Assisted↗

PubMed1992

Teleradiology via narrow-band integrated services digital network (N-ISDN) and Joint Photographic Experts Group (JPEG) image compression.

The importance of remote access to both radiological images and medical information has stimulated many demonstration projects that use a variety of telecommunications providers' offerings. Teleradiology, through modest cost channels, can achieve adequate response times using a combination of narrow-band integrated services digital network (N-ISDN) and data compression. A demonstration project, developed in collaboration with Southwestern Bell Technology Resources, Inc, uses the aggregate bandwidth of two B channels (achieving a rate of 120 kilobits per second) and a block-oriented discrete cosine transform compression/decompression implementation based on the Joint Photographic Experts Group Standard for Still Image Compression. System response measurements for an Inquiry and Display Station accessing the Mallinckrodt Institute of Radiology's Radiology Image and Information Management Testbed via the N-ISDN connection show response times to be within 20 seconds. Viewing applications have been shown at sites within St Louis and at Radiological Society of North America, 1990, in Chicago.

Computer Communication Networks↗

PubMed1990

Perimeter encoding for teleradiology.

Perimeter encoding is a technique of data compression that is done simply by outlining the area of interest on an examination. In a sample of 92 emergency room examinations (excluding chest, abdomen, and pelvic exams), 304 films were interpreted by a resident radiologist who indicated the area of interest by marking four corners of a rectangle. The adequacy of the area of interest was determined by a staff osteoradiologist during subsequent review of the films. The amount of data reduction was measured by determining the ratio of the area of interest inside a rectangle to the area of the film (compression ratio). The overall average compression ratio was 3 to 1. This preliminary study suggests that further evaluation of perimeter encoding is warranted.

Emergency Medical Service Communication Systems↗

PubMedDate not supplied

Radiological image compression using full-frame cosine transform with adaptive bit-allocation.

We report a new bit-allocation scheme based on the full-frame cosine transform for radiological image compression. The new technique differs from a previously reported method in its use of a two-dimensional bit-allocation table to encode the compression data. This allows for an improved treatment of high frequency components in the transform domain. Consequently, it has the capability of faithfully reproducing limited numbers of high-contrast sharp edges in the image. Previously reported artifacts, induced in the reconstructed image by sharp edges in the original, have been eliminated. Experiments with 10 radiological chest images show almost no perceivable degradation in the reconstructed image at compression ratios below 10:1. Image quality at a fixed compression ratio is, in every case, comparable or superior to results using the old method. Furthermore, the new algorithm lends itself to hardware implementations that are both simple and fast.

Algorithms↗

PubMedDate not supplied

Selective archiving of radiologic images.

The increasing number of radiographic images is a problem in most radiology departments. The problem will be emphasized with the introduction of digital acquisition and storage of radiographs. Changes in image management strategies will therefore become necessary. Such strategies will have great technologic and financial impact and will probably determine the applicability and success of digital radiography. Based on the experience that not all radiographs are equally important and on the assumption that not every image in a radiology archive can be maintained on-line, we investigated the effect of storing only selected, clinically informative radiographs; i.e., clinical data compression. In 165 routine examinations (77 barium enemas, 16 barium meals and 72 urographies) 2433 films were used (14.7 films per examination). We archived only the 461 films (19%) which were considered to be of future informative value. During a one-year follow-up period none of the 1972 removed films was requested. This indicates that a considerable number of films and a considerable amount of image data can be removed from the archive without affecting the clinical work.

Humans↗

PubMed1991

Circular harmonic averaging of rotary-shadowed and negatively stained creatine kinase macromolecules.

The structure of mitochondrial creatine kinase is investigated by high-resolution shadowing at very low temperature and conventional negative staining. The electron microscopic images are analyzed with circular harmonic averaging, a method suited for the processing of single molecules. The rotational alignment and averaging is performed with the circular harmonic components, which allows data compression and several steps of noise reduction to be carried out within the averaging procedure. In addition, the symmetry can be deduced. For the mitochondrial creatine kinase, a fourfold symmetry is found that is compatible with the biochemical and biophysical characterization of the molecule.

Creatine Kinase↗

PubMed1991

Flexibility of globular proteins in water as revealed by compressibility.

In order to elucidate the flexibility-structure-function relationships of proteins, the adiabatic compressibility of about 30 globular proteins, including food proteins, was determined by means of sound velocity and density measurements in aqueous solutions. Most proteins studied showed positive compressibility, indicating the large internal flexibility of the molecules. The volume fluctuation was in the range of 30-200 ml/mol, which corresponded to about 0.3% of the total protein volume. From the statistical analyses of the compressibility data, it was found that the flexibility of proteins is closely related to structural factors such as hydrophobicity, helix element, and amino acid composition, and to functional properties such as digestibility and foaming capacity. These results indicate that the dynamics of protein structure should be taken into account in predicting precisely the functions and properties of a protein from its primary or tertiary structure.

Amino Acids↗

PubMed1991

The application of delta modulation to EEG waveforms for database reduction and real-time signal processing.

The large volume of digital data and the demanding processing task involved in electroencephalogram (EEG) analysis place stringent requirements on computer resources in terms of data transfer, computation speed, and temporary or permanent storage. The reduction of the database to a manageable size is therefore necessary for economical use of transmission channels and the storage media. The two criteria, waveform reproducibility and processing applications, must be analyzed and optimized in terms of signal-to-noise ratio (SNR) using the various factors affecting the coding. This analysis and optimization can become cumbersome, and a specialized workstation has been developed specifically for analysis of digital coding. Our interest in data compression stems from the study of the feasibility of predicting pilots' acceleration (Gz) tolerance during flight by processing both their uncoded and coded EEG.

Aerospace Medicine↗

PubMed1991

Management and clinical utilization of computed tomography, magnetic resonance imaging, and angiography in Hokkaido University Hospital picture archiving and communication system.

We made a preliminary assessment of the Hokkaido University picture archiving and communication system (HU-PACS). Data access time from either imaging machines or data base to workstations was 1.5 minutes, which is great benefit for data communication in routine examinations. Image quality of the work station was estimated in terms of brain computed tomography (CT) and digitized cerebral angiograms. Cerebral infarction was definitely observed on the cathode-ray tube (CRT) monitor of the work station. Although the picture quality of CRT was acceptable, we had to manipulate window level and width for CRT diagnosis of cerebral angiography. Data compression was routinely used without significant degradation of those image quality. Nevertheless, further improvement of maneuverability of the workstation should be considered.

Angiography, Digital Subtraction↗

PubMed1979

A computer feedback system for clinical research.

This paper presents a computerized data base management and information retrieval system for a heroin addiction research clinic, which has potential application for any type of clinical research. It describes data input checking programs, file structures, and output programs. The system contains several interesting features: built-in feedback error detection and correction; patient month matrix formatting and data compression; and a virtual blocking system to reduce the size of the files.

Computers↗

PubMed1992

Image manipulation: digital versus analog.

A conceptual difference between "analog" and "digital" digitizing is reviewed. Analog and digital type image filing systems are discussed from a comparative point of view: The analog type is advantageous in the number of recordable images, the recording and reproducing speed, and the ability to record a moving picture, while the digital type, in which images are digitized when recorded, is capable of reproducing a higher quality image that does not deteriorate when copied repeatedly. It has the advantage that it easily interfaces with computer systems. As technology developed to compensate for the drawbacks of the digital type systems, image data compression was introduced. Finally, the possibility for recording a moving picture in a digital type system is discussed.

Image Processing, Computer-Assisted↗

PubMed1989

Evaluation of routine telephone transmission of nuclear medicine studies.

Rapid and reliable transmission of nuclear medicine studies using conventional telephone lines and commercially available modems and computer systems has been accomplished through use of software developed within the authors' hospital. Original digital images of all-night and weekend studies, acquired on any of the acquisition computers from different manufacturers, are now routinely sent for remote reading at the physician's home. Data, software, and letters are routinely exchanged using modems and standard telephone lines with a sister institution in Haifa, Israel. The software has been designed to achieve no loss data compression and minimal turnaround time loss. Thus, an average lung perfusion image or gallbladder study requires about 1-3 minutes of transmission time. Full analysis and display software is available on the remote computer.

Computer Communication Networks↗

PubMed1991

[Thyroid carcinoma as cystic nodule. The diagnostic role of cytology by needle aspiration].

195 patients affected by a cystic thyroid lesion were studied by a Fine Needle Aspiration biopsy (FNAb). 42 patients were operated on account of clinical data, compressive phenomena or cytologic results suggesting a neoplasia. Out of the operated patients, 3 were affected by a carcinoma in the cystic lesion (one "pure" cystic nodule and two "mixed" ones), while three more patients with multinodular goiters showed a carcinomatous lesion in a nodule different from the cystic one. Macroscopic characteristics of the aspirated fluid (quantity and quality) didn't affect the cytologic diagnosis. Cytology was useful in the preoperative diagnosis of benign thyroid nodules (only two false positives out of 42 patients) and was diagnostic in all the three patients affected by a carcinoma in the cystic nodule.

Adolescent↗

PubMed1991

Digital imaging and picture archiving and communication systems.

Great progress has been made in digital imaging of the chest. Most studies are dealing with computed radiography. Chest radiography in the intensive care unit may, in most cases, be performed using computed radiography. However, subtle pulmonary interstitial disease can be demonstrated less confidently using computed radiography. Significantly better detection of calcified lung nodules can be obtained by using simplified single-exposure dual-energy technique that uses storage phosphor. The wide latitude of computed radiography permits images of high quality in areas other than chest radiography. Encouraging results are presented especially in the diagnostic evaluation of scoliosis and other musculoskeletal abnormalities. An important technical innovation in digital radiography is an improved method for single-exposure dual-energy digital imaging using prefiltration with gadolinium, a cassette consisting of four photostimulable phosphor plates, spatially dependent scatter and beam hardening corrections, and noise reduction algorithm. Other groups tested algorithms for enhancement of digital images that allowed significant data compression. The implementation of picture archiving and communication systems (PACS) is inevitable; the question concerning PACS implementation is not why, but when. A comparison of the cost-effectiveness of PACS with conventional film archiving and communication systems shows that PACS should provide indirect savings when regarding the hidden costs of conventional systems. Much more experience will be needed before there is general agreement on the best design for the radiologist's workstation. Teleradiology should contribute to radiologic consultation for remote locations, because it improves the efficacy of management of patients in such locations.

Child↗

PubMed1989

Shape description in osteology using automatic Fourier analysis. Example of the human atlas.

An image analysing procedure for the shape characterisation in osteology is described. We used expansion in Fourier series of an equiangular polar representation of the contour. Fourier analysis is an information preserving technique, and it is therefore possible to reconstruct the original contour from the shape descriptors (Fourier coefficients and descriptors). The properties of the truncated expansion of the Fourier series can be used for smoothing effect and noise reduction, for interpolated reconstruction, and for data compression. Fourier analysis also allows a quantitative description of the shape. The first components describe the gross feature, the following ones the fine details.

Cervical Atlas↗

PubMed1975

Computer signal processing of long duration biotelemetric brain data.

The EEG represents brain processing under diverse physiological conditions. A complete system involving acquisition and quantitation of this important information about brain function is described. The time-domain EEG and other biological signals are obtained using a multichannel PAM/FM biotelemeter mounted on the head of the experimental animal. This data is transmitted, demodulated and recorded by electronic recording techniques. A computer-based EEG analysis system is described for acquiring the primary data and transforming it into the frequency domain using Fourier methods. The computing system is developed to semi-automatically signal process about 4 h of eight channel EEG records. Data compression by plotting in a quasi-three-dimensional spectral profile allows visual correlations of pattern features to drug manipulations, etc. The software programs are briefly described for each step in signal processing. The feasibility of the complete system approach is demonstrated using biotelemetry to acquire low voltage EEG signals without behavioral distortions or introduction of artifacts by cables.

Animals↗