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PubMed1994

An information manager for the Assessment Protocol for Excellence in Public Health.

The Assessment Protocol for Excellence in Public Health (APEXPH) is a method for comprehensive public health planning that can be implemented by state and local health departments. Many local health departments have limited resources for the data analysis and synthesis needed for APEXPH. To facilitate the implementation of APEXPH in Michigan, we used the Centers for Disease Control and Prevention (CDC) Epi Info software package to develop an APEXPH information manager (CDC-AIM) for use by the 50 local health departments in that state. This report describes our methods for formatting, compressing, and presenting data. Examples of tables are provided for demographics by age and sex, numbers of deaths, years of potential life lost, crude mortality rates, and perinatal indicators such as low birthweight. Areas where additional work is needed to further improve CDC-AIM are discussed. Our experience in Michigan suggests that CDC-AIM potentially is an extremely helpful tool to assist state and local health departments in working with their communities to establish public health program plans based on mortality, morbidity, and risk-factor data.

Comprehensive Health Care↗
PubMed2003

Immediate sheath removal after PCI using a Femostop is feasible and safe. Results of a registry.

BACKGROUND: Due to antithrombotic therapy before, during, and after percutaneous coronary intervention (PCI), and due sometimes to the need for an urgent reintervention, the arterial femoral sheath is generally not removed immediately after PCI, unless a vascular closing device is used. This strategy causes discomfort to the patient, increases the workload for the nursing staff, and bears a risk of local complications. OBJECTIVE: The purpose of this registry is to demonstrate that immediate sheath removal after PCI is safe and feasible with the ultimate goal of enhancing patient care and hospital efficiency. METHODS: In patients undergoing PCI, the femoral arterial sheath was removed immediately after PCI in the cath lab, using a Femostop, without manual compression. The patient's discomfort and the complication rate were measured. The overall time given to haemostasis was assessed. RESULTS: A total of 339 patients were included. Patient discomfort during Femostop placement was assessed as follows: 85% suffered none, 2% slight, 3% moderate, and 10% severe discomfort. Complication rates were: 36% ecchimosis, 10% haematoma < 6 cm, 5% haematoma > or = 6 cm (literature data of manual compression--LDMC--5.1% to 9%), 1% pseudoaneurysm (LDMC 1% to 1.8%), 0.6% need for transfusion (LDMC 2.5%), 0.3% need for vascular repair (LDMC 1.5% to 2.7%). The patient's immobilisation time after PCI was reduced from at least 10 hours to 6 hours. The time given to haemostasis was also reduced. CONCLUSION: Immediate sheath removal using a Femostop is feasible, safe, and improves the patient's comfort. The complication rate is equal or even lower to that reported after classical manual compression. Early ambulation improves the patient's comfort, and reduced time given to haemostasis causes organisational benefit. If a vascular closing device is not routinely used after PCI (for example, for economical reasons), immediate sheath removal after PCI could be the routine strategy.

Adult↗
PubMed2006

Detecting computer-induced errors in remote-sensing JPEG compression algorithms.

The JPEG image compression standard is very sensitive to errors. Even though it contains error resilience features, it cannot easily cope with induced errors from computer soft faults prevalent in remote-sensing applications. Hence, new fault tolerance detection methods are developed to sense the soft errors in major parts of the system while also protecting data across the boundaries where data flow from one subsystem to the other. The design goal is to guarantee no compressed or decompressed data contain computer-induced errors without detection. Detection methods are expressed at the algorithm level so that a wide range of hardware and software implementation techniques can be covered by the fault tolerance procedures while still maintaining the JPEG output format. The major subsystems to be addressed are the discrete cosine transform, quantizer, entropy coding, and packet assembly. Each error detection method is determined by the data representations within the subsystem or across the boundaries. They vary from real number parities in the DCT to bit-level residue codes in the quantizer, cyclic redundancy check parities for entropy coding, and packet assembly. The simulation results verify detection performances even across boundaries while also examining roundoff noise effects in detecting computer-induced errors in processing steps.

Algorithms↗
PubMed1984

Thermodynamic properties of purple membrane.

We measured the density, expansivity, specific heat at constant pressure, and sound velocity of suspensions of purple membrane from Halobacterium halobium and their constituent buffers. From these quantities we calculated the apparent values for the density, expansivity, adiabatic compressibility, isothermal compressibility, specific heat at constant pressure, and specific heat at constant volume for the purple membrane. These results are discussed with respect to previously reported measurements on globular proteins and lipids. Our data suggest a simple additive model in which the protein and lipid molecules expand and compress independently of each other. However, this simple model seems to fail to describe the specific heat data. Our compressibility data suggest that bacteriorhodopsin in native purple membrane binds less water than many globular proteins in neutral aqueous solution, a finding consistent with the lipid surround of bacteriorhodopsin in purple membrane.

Bacteriorhodopsins↗
PubMed1975

[Acoustic investigations in orbital tumor diagnosis (author's transl)].

360 patients with unilateral exophthalmos were examined with echoophthalmograph to study the diagnostical possibilities of a method of echography in orbital tumors. The findings of para- and transbulbal methodics were checked in 140 patients. The tonometry of tumors and soft orbital tissues was performed. The methodics of acoustic orbitonometry based on the measurement of retrobulbal neoplasms at the moment of their step-by-step compression was worked out. The echographic symptoms of different orbital neoplasms is described as well as those of pseudotumor and tireotropic exophthalmos. The possibility of acoustic measurement of orbital neoplasms is shown. The dependence between the extent and progress of deformation in the exophthalmed eye on one hand-nature of exophthalmos, character and localization of the tumor on the other was revealed. The quantitative data about the compression of different orbital tumors were obtained. It was shown that the surveying echography, biometry and acoustic orbitonometry facilitate the task of differential diagnosis, allow the localization and size of the tumor to be detected and help to control the results of the treatment.

Anthropometry↗
PubMed1999

Discrete wavelet transform: a tool in smoothing kinematic data.

Motion analysis systems typically introduce noise to the displacement data recorded. Butterworth digital filters have been used to smooth the displacement data in order to obtain smoothed velocities and accelerations. However, this technique does not yield satisfactory results, especially when dealing with complex kinematic motions that occupy the low- and high-frequency bands. The use of the discrete wavelet transform, as an alternative to digital filters, is presented in this paper. The transform passes the original signal through two complementary low- and high-pass FIR filters and decomposes the signal into an approximation function and a detail function. Further decomposition of the signal results in transforming the signal into a hierarchy set of orthogonal approximation and detail functions. A reverse process is employed to perfectly reconstruct the signal (inverse transform) back from its approximation and detail functions. The discrete wavelet transform was applied to the displacement data recorded by Pezzack et al., 1977. The smoothed displacement data were twice differentiated and compared to Pezzack et al.'s acceleration data in order to choose the most appropriate filter coefficients and decomposition level on the basis of maximizing the percentage of retained energy (PRE) and minimizing the root mean square error (RMSE). Daubechies wavelet of the fourth order (Db4) at the second decomposition level showed better results than both the biorthogonal and Coiflet wavelets (PRE = 97.5%, RMSE = 4.7 rad s-2). The Db4 wavelet was then used to compress complex displacement data obtained from a noisy mathematically generated function. Results clearly indicate superiority of this new smoothing approach over traditional filters.

Algorithms↗
PubMed2005

Space-efficient whole genome comparisons with Burrows-Wheeler transforms.

The starting point for any alignment of mammalian genomes is the computation of exact matches satisfying various criteria. Time-efficient, O(n), data structures for this computation, such as the suffix tree, require O(n log(n)) space, several times the space of the genomes themselves. Thus, any reasonable whole-genome comparative project finds itself requiring tens of Gigabytes of RAM to maintain time-efficiency. This is beyond most modern workstations. With a new data structure, the compressed suffix array (CSA) implemented via the Burrows-Wheeler transform, we can trade time-efficiency for space-efficiency, taking O(n log(n)) time, but running in O(n) space, typically in total space less than or equal to that of the genomes themselves. If space is more expensive than time, this is an appropriate approach to consider. The most space-efficient implementation of this data structure requires 5 bits per nucleotide character to build on-line, in the worst case, and 2.5 bits per character to store once built. We present a description of this data structure and how it is used to obtain matches. An implementation (called bbbwt) is demonstrated by aligning two mammalian genomes on a modest workstation equipped with under 2 GB of free RAM in time superior to that of the implementations of other data structures.

Animals↗
PubMed1996

Normal saturation processing provides a model for understanding the effects of disease on color perception.

Saturation discrimination has been reported to be affected early in the course of a disease. Our empirical data show a compressive curvi-linear relationship between opponent/nonopponent channel activity and saturation thresholds in normal trichromatic observers. This relationship can be explained by a model based on the Hurvich and Jameson saturation coefficient (1957), Psychology Reviews, 64, 384-404. The model considers effects of both selective and nonselective channel losses on saturation processing based on the assumption that disease produces elevated thresholds while maintaining normal psychometric response functions. Both the model and data support clinical observations of saturation losses occurring early in disease. However, the results also indicate that saturation may not be the best modality for monitoring long-term progression of such conditions. We suggest that the different processing characteristics for blue-yellow thresholds may yield added information for saturation testing under some circumstances and that saturation processing occurs at a higher cortical level.

Adult↗
PubMed1998

Automatic EEG analysis during long-term monitoring in the ICU.

To assist in the reviewing of prolonged EEGs, we have developed an automatic EEG analysis method that can be used to compress the prolonged EEG into two pages. The proposed approach of Automatic Analysis of Segmented-EEG (AAS-EEG) consists of 4 basic steps: (1) segmentation; (2) feature extraction; (3) classification; and (4) presentation. The idea is to break down the EEG into stationary segments and extract features that can be used to classify the segments into groups of like patterns. The final step involves the presentation of the processed data in a compressed form. This is done by providing the EEGer with a representative sample from each group of EEG patterns and a compressed time profile of the complete EEG. To verify the above approach, 41 6 h EEG records were assessed for normality via the AAS-EEG and conventional EEG approaches. The difference between the overall assessment via compressed and conventional EEG was within one abnormality level 100% of the time, and within one-half level for 73.6% of the records. We demonstrated the feasibility and reliability of automatically segmenting and clustering the EEG, thus allowing the reduction of a 6 h tracing to a few representative segments and their time sequence. This should facilitate review of long recordings during monitoring in the ICU.

Child↗
PubMed1983

Adults' item and order errors on sequences of time-compressed rhyming words.

This investigation provided normative data for the intelligibility of time-compressed (TC) phonemes in 40 normal-hearing adults aged 18-26 yrs. Individual Ss were presented with 5-word rhyming sequences from the Fairbanks Rhyme Test (e.g., cat-bat-hat-mat-rat) sent to a monaural earphone at 40 db re SRT, and required to write the initial phonemes in the order as heard. Sequences were either at normal speed or at 60% TC, either unmasked or under contralateral multitalker masking at 65 db re SRT, counterbalanced for ear (R,L) and presentation order (R-L, L-R). Significant effects for both TC and masking were obtained with separate analyses of item and order errors. The findings support the diagnostic potential of these stimuli in detecting and documenting subtle auditory perceptual problems in adults, since they were consistent with findings for other stimuli known to be diagnostically effective and have the further property of tapping memory and sequencing abilities. Significant interactions with the factor of ear (R vs L) suggest that the stimuli may be especially sensitive to ear differences. Similar studies with groups such as those with high-level aphasia, sickle cell anemia, repeated strokes, etc., should be forthcoming to determine the clinical utility of these materials and procedures.

Adolescent↗
PubMed2000

Dosimetric implications of age related glandular changes in screening mammography.

The UK National Health Service Breast Screening Programme is currently organized to routinely screen women between the ages of 50 and 64, with screening for older women available on request. The lower end of this age range closely matches the median age for the menopause (51 years), during which significant changes in the composition of the breast are known to occur. In order to quantify the dosimetric effect of these changes, radiographic factors and compressed breast thickness data for a cohort of 1258 women aged between 35 and 79 undergoing breast screening mammography have been used to derive estimates of breast glandularity and mean glandular dose (MGD), and examine their variation with age. The variation of mean radiographic exposure factors with age is also investigated. The presence of a significant number of age trial women within the cohort allowed an extended age range to be studied. Estimates of MGD including corrections for breast glandularity based on compressed breast thickness only, compressed breast thickness and age and for each individual woman are compared with the MGD based on the conventional assumption of a 50:50 adipose/glandular composition. It has been found that the use of the conventional 50:50 assumption leads to overestimates of MGD of up to 13% over the age range considered. By using compressed breast thickness to estimate breast glandularity, this error range can be reduced to 8%, whilst age and compressed breast thickness based glandularity estimates result in an error range of 1%.

Adult↗
PubMed1991

SLOPE--a real-time ECG data compressor.

An ECG sampled at a rate of 250 samples s-1 or more produces a large amount of redundant data that are difficult to store and transmit. In the paper, a real-time ECG data compressor, SLOPE, is presented. SLOPE considers some adjacent samples as a vector, and this vector is extended if the coming sample falls in a fan spanned by this vector and a threshold angle; otherwise, it is delimited as a linear segment. By this means SLOPE repeatedly delimits linear segments of different lengths and different slopes. The Huffman codes for the parameters to describe this linear segment are transmitted for that linear segment. SLOPEa, which is a slightly modified version of SLOPE, is used to compress ambulatory ECG data. All the operations used by SLOPE and SLOPEa are simple integer operations, both SLOPE and SLOPEa being real-time compressors. Experimental results show that an average of 192 bits per channel per second (bpcs) for each ECG signal is obtained by SLOPE and an average of 148 bpcs for each ECG signal is obtained by SLOPEa.

Computer Systems↗
PubMed2007

Improvement of elastographic displacement estimation using a two-step cross-correlation method.

The cross-correlation algorithm used to compute the local strain components for elastographic imaging requires a minimum radio-frequency data segment length of around 10 wavelengths to obtain accurate and precise strain estimates with a reasonable signal-to-noise ratio. Shorter radio-frequency data segments generally introduce increased estimation errors as the information content in the data segment reduces. However, shorter data segments and increased overlaps are essential to improve the axial resolution in the strain image. In this paper, we propose a two-step cross-correlation technique that enables the use of window lengths on the order of a single wavelength to provide displacement and strain estimates with similar noise properties as those obtained with a 10 wavelength window. The first processing step utilizes a window length on the order of 10 wavelengths to obtain coarse displacement estimates between the pre- and post-compression radio frequency data frames. This coarse displacement is then interpolated and utilized as the initial guess-estimate for the second cross-correlation processing step using the smaller window. This step utilizes a single wavelength window to improve the axial resolution in strain estimation, without significantly compromising the noise properties of the image. Simulation and experimental results show that the signal-to-noise and contrast-to-noise ratio estimates improve significantly at the smaller window lengths with the two-step processing when compared with the use of a similar sized window in the currently utilized single window method.

Elasticity↗
PubMed1999

Fluorescence and FTIR study of the pressure-induced denaturation of bovine pancreas trypsin.

The pressure denaturation of trypsin from bovine pancreas was investigated by fluorescence spectroscopy in the pressure range 0. 1-700 MPa and by FTIR spectroscopy up to 1000 MPa. The tryptophan fluorescence measurements indicated that at pH 3.0 and 0 degrees C the pressure denaturation of trypsin is reversible but with a large hysteresis in the renaturation profile. The standard volume changes upon denaturation and renaturation are -78 mL.mol-1 and +73 mL.mol-1, respectively. However, the free energy calculated from the data in the compression and decompression directions are quite different in absolute values with + 36.6 kJ.mol-1 for the denaturation and -5 kJ. mol-1 for the renaturation. For the pressure denaturation at pH 7.3 the tryptophan fluorescence measurement and enzymatic activity assays indicated that the pressure denaturation of trypsin is irreversible. Interestingly, the study on 8-anilinonaphthalene-1-sulfonate (ANS) binding to trypsin under pressure leads to the opposite conclusion that the denaturation is reversible. FTIR spectroscopy was used to follow the changes in secondary structure. The pressure stability data found by fluorescence measurements are confirmed but the denaturation was irreversible at low and high pH in the FTIR investigation. These findings confirm that the trypsin molecule has two domains: one is related to the enzyme active site and the tryptophan residues; the other is related to the ANS binding. This is in agreement with the study on urea unfolding of trypsin and the knowledge of the molecular structure of trypsin.

Anilino Naphthalenesulfonates↗
PubMed2001

Accuracy and cost- and time-effectiveness of digital clip versus videotape interpretation of echocardiograms in patients with valvular disease.

BACKGROUND: Although digital and videotaped images are known to be comparable for the evaluation of left ventricular function, their relative accuracy for assessment of more complex anatomy is unclear. We sought to compare reading time, storage costs, and concordance of video and digital interpretations across multiple observers and sites. METHODS: One hundred one patients with valvular (90 mitral, 48 aortic, 80 tricuspid) disease were selected prospectively, and studies were stored according to video and standardized digital protocols. The same reviewer interpreted video and digital images independently and at different times with the use of a standard report form to evaluate 40 items (e.g., severity of stenosis or regurgitation, leaflet thickening, and calcification) as normal or mildly, moderately, or severely abnormal. Concordance between modalities was expressed at kappa. Major discordance (difference of >1 level of severity) was ascribed to the modality that gave the lesser severity. CD-ROM was used to store digital data (20:1 lossy compression), and super-VHS videotape was used to store video data. The reading time and storage costs for each modality were compared. RESULTS: Measured parameters were highly concordant (ejection fraction was 52% +/- 13% by both). Major discordance was rare, and lesser values were reported with digital rather than video interpretation in the categories of aortic and mitral valve thickening (1% to 2%) and severity of mitral regurgitation (2%). Digital reading time was 6.8 +/- 2.4 minutes, 38% shorter than with video (11.0 +/- 3.0, range 8 to 22 minutes, P <.001). Compressed digital studies had an average size of 60 +/- 14 megabytes (range 26 to 96 megabytes). Storage cost for video was A$0.62 per patient (18 studies per tape, total cost A$11.20), compared with A$0.31 per patient for digital storage (8 studies per CD-ROM, total cost A$2.50). CONCLUSION: Digital and video interpretation were highly concordant; in the few cases of major discordance, the digital scores were lower, perhaps reflecting undersampling. Use of additional views and longer clips may be indicated to minimize discordance with video in patients with complex problems. Digital interpretation offers a significant reduction in reading times and the cost of archiving.

CD-ROM↗
PubMed1998

Vestibular schwannoma management in the next century: a radiosurgical perspective.

PURPOSE: To discuss how the evolution of vestibular schwannoma radiosurgery, changes in health care delivery, and patient accessibility to medical information will affect the management of vestibular schwannomas in the future. CONCEPT: In comparison with microsurgical resection of vestibular schwannomas, radiosurgery has a lower morbidity rate, a similar risk of requiring further surgery, and higher patient satisfaction. As this information becomes more widely available to patients and third-party payors, radiosurgery may replace surgical resection as the preferred management strategy for patients with small to medium sized vestibular schwannomas in the United States. RATIONALE: It is estimated that 2500 patients are diagnosed with vestibular schwannomas each year in the United States. Assuming that 80% undergo surgery, 2000 operations are performed annually for newly diagnosed vestibular schwannomas. Data available since 1987 regarding the number of cases for which gamma knife radiosurgery was performed were used to predict the number of patients who will undergo vestibular schwannoma radiosurgery in the future. If the current trend continues, an equal number of patients will undergo surgical resection and radiosurgery to treat their vestibular schwannomas (approximately 1000/yr) sometime between 2005 and 2010. Moreover, it is predicted that by 2020, two-thirds of the patients who are newly diagnosed with vestibular schwannomas will undergo radiosurgery, with surgical resection being reserved for patients with large tumors associated with symptomatic brain stem compression. DISCUSSION: Early data regarding vestibular schwannoma radiosurgery predicted an exponential growth curve. Although it is premature to assume that the current trend will continue, it is likely that an ever increasing percentage of patients will undergo radiosurgery as accessibility to this alternative increases, and more data are published regarding long-term tumor growth control rates. If the mathematical model proves to be accurate, then stereotactic radiosurgery will replace surgical resection as the preferred management strategy for the majority of patients with vestibular schwannomas.

Delivery of Health Care↗
PubMed1995

Is the stroke belt disappearing? An analysis of racial, temporal, and age effects.

BACKGROUND AND PURPOSE: The stroke risk among white residents of the coastal plain of North Carolina, South Carolina, and Georgia (the "Stroke Belt") has been reported to be between 1.3 and 2.0 times the national average. In this study we examined (1) whether a similar excess risk exists for blacks in this region, (2) whether this regional excess stroke risk has decreased over time, and (3) whether the regional excess risk is consistent across ages from 45 to more than 85 years. METHODS: Using data from the Compressed Mortality File, we estimated the annual relative stroke mortality risk for black and white men and women in a region of 153 coastal plain counties and compared these rates to those for the remainder of the United States. RESULTS: The relative geographic excess risk of stroke death was similar for black residents and white residents of the Stroke Belt for both men and women. Despite the decline in stroke mortality, the relative increased risk of stroke death in the region has remained constant from 1968 to 1991; however, the pattern of excess risk across age differed significantly between race/sex groups. CONCLUSIONS: These data show that the Stroke Belt continues to exist for blacks and whites and for men and women. Although the specific causes of the Stroke Belt remain unknown, the public health impact is staggering, with a greater than 40% excess risk of stroke mortality and more than 1200 excess stroke deaths annually.

Age Factors↗
PubMed1998

The Kodak approach to digital cardiovascular imaging laboratories.

Cine film had been a global standard in the cardiac catheterization lab for the acquisition, archive, review and exchange for decades. The advent of digital imaging in the cath lab heightened the desire to store cath procedure images in a digital format. The issues related to the development of a digital exchange standard, the data capacities and data rates, lossless and lossy compression, and techniques to obtain digital image data from the lab are discussed. In addition, Kodak's approach to cine film replacement with digital systems is described.

Cardiac Catheterization↗