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PubMed1991

Effects of stimulus context on magnitude estimations and category ratings of perceived loudness--the spacing of intensity intervals.

Effects of stimulus context on magnitude estimations and on category ratings were examined for a range of stimulus intensities of a 1-kHz tone. The stimuli were distributed in equal-interval steps of energy so they formed a perceptual cluster of high-intensity tones with a perceptual outlier at the lowest intensity. According to the Invariance Principle, the shape of the response function should not be affected by the distribution of stimulus intensities. However, neither magnitude estimations nor category ratings yielded the linear functions predicted from the Invariance Principle when plotted on log-log axes. Instead, both procedures yielded concave-upward response functions for the group data as well as for the individual data sets of the six subjects. Moreover, unlike previous reports of a nonlinear relationship, we found a linear relationship between magnitude estimations and category ratings. Rather than implying an equivalence of the underlying sensory scales, however, our results may imply subjects used a similar attention strategy for both procedures. We consider some theoretical suggestions, including an attention-band concept, for modification of a multistage stimulus-response (S-R) transformation model.

Adult↗
PubMed2001

[3D visualization and information interaction in biomedical applications].

3D visualization and virtual reality are important trend in the development of modern science and technology, and as well in the studies on biomedical engineering. This paper presents a computer procedure developed for 3D visualization in biomedical applications. The biomedical models are constructed in slice sequences based on polygon cells and information interaction is realized on the basis of OpenGL selection mode in particular consideration of the specialties in this field such as irregularity in geometry and complexity in material etc. The software developed has functions of 3D model construction and visualization, real-time modeling transformation, information interaction and so on. It could serve as useful platform for 3D visualization in biomedical engineering research.

Biomedical Engineering↗
PubMedDate not supplied

[Relative reactivity of thiamine monophosphate and thiamine diphosphate upon interaction with alkaline phosphatase].

Reactivity of thiamin monophosphate (TMP) as calf intestinal alkaline phosphatase substrate in model transformations is lower comparing with thiamin diphosphate (TDP) reactivity. Under these conditions alkaline phosphatase catalyzes TDP, ADP and AMP hydrolysis approximately at same rate. It was shown that TDP competes with p-nitrophenyl phosphate more effectively than TMP for the binding in the active site. At pH 8.5 and 30 degrees C Km values are as follows: (5.2 +/- 1.6) x 10(-3) M for TMP and (3.0 +/- 0.8) x 10(-4) M for TDP. Under the same conditions the Vmax/Km value for TDP hydrolysis is 53 times higher than the one for corresponding reaction of TMP. It was suggested that positively charged thiazolium ion of TMP interacts with the nearest environment at the active center and by this way reduces enzyme activity.

Alkaline Phosphatase↗
PubMed2003

Department of Defense medical transformation: a case for the Defense Health Agency.

What are the threats facing the military health system (MHS) in the first quarter of the 21st century? The Department of Defense has decided that the emerging threats of weapons of mass destruction, information and asymmetrical warfare, well-organized terrorist groups, and rogue nations are going to require a transformation in future force structure and operational concepts. Is the MHS continuing to train and equip itself for the battlefield casualties of the Korean and Vietnam conflicts, or is it truly prepared for the emerging threats of the 21st century? Reliance on gradual, incremental change will not be sufficient to combat new emerging threats to the United States. Transformation is a radical concept; it demands a wholesale review of how the MHS views and accomplishes the mission. It does not accept the comfort afforded by slow, gradual evolution in military doctrine and organizational structure that bureaucracy affords. The Department of Defense is transforming. The MHS also needs to embrace transformational restructuring; to train and equip for the war on the horizon, to keep pace with the warfighter, and to provide integration and interoperability with other federal, state, and local agencies in support of homeland defense. More than two dozen formal audits, boards, studies, and reviews have questioned the necessity, efficiency, and effectiveness of the three services medical departments; yet the MHS has undergone little transformational change since World War II. The transformational model that will best support the operational forces and the United States in the coming decades is the Defense Health Agency model.

Forecasting↗
PubMed2003

Response surfaces for climate change impact assessments in urban areas.

Assessment of the impacts of climate change in real-world water systems, such as urban drainage networks, is a research priority for IPCC (Intergovernmental Panel of Climate Change). The usual approach is to force a hydrological transformation model with a changed climate scenario. To tackle uncertainty, the model should be run with at least high, middle and low change scenarios. This paper shows the value of response surfaces for displaying multiple simulated responses to incremental changes in air temperature and precipitation. The example given is inflow, related to sewer infiltration, at the Lycksele waste water treatment plant. The range of plausible changes in inflow is displayed for a series of runs for eight GCMs (Global Circulation Model; ACACIA; Carter, 2002, pers. comm.). These runs are summarised by climate envelopes, one for each prediction time-slice (2020, 2050, 2080). Together, the climate envelopes and response surfaces allow uncertainty to be easily seen. Winter inflows are currently sensitive to temperature, but if average temperature rises to above zero, inflow will be most sensitive to precipitation. Spring inflows are sensitive to changes in winter snow accumulation and melt. Inflow responses are highly dependent on the greenhouse gas emission scenario and GCM chosen.

Cities↗
PubMed2005

[Advances in medical image registration based on mutual information].

The matching algorithm based on mutual information, which has the advantages of high speed, good automation and superion accuracy, is widely used in medical image registration. In this paper are presented the basic conception of mutual information, the transform model, the insert value algorithm, the optimization algorithm and the strategy in computing mutual information. Furthermore, we introduce some efficient methods for solving the problems in registration technique based on mutual information, and look forward to the future research work.

Algorithms↗
PubMed1988

In vitro growth patterns and autocrine production of hemopoietic colony stimulating factors: analysis of leukemic populations arising in irradiated mice from cells of an injected factor-dependent continuous cell line.

Cells of the factor-dependent hemopoietic cell line FDC-P1 become leukemic when injected intravenously to irradiated syngeneic mice. An analysis of 117 cell lines derived from 17 such leukemic mice showed that they displayed different patterns of growth in vitro ranging from full autonomy to absolute dependency on stimulation by granulocyte-macrophage colony stimulating factor (GM-CSF) or multipotential colony stimulating factor (multi-CSF). In contrast to parental FDC-P1 cells, even the factor-dependent variant cell lines were tumorigenic in vivo. The behavior of these latter cell lines could not be explained by hyperresponsiveness to CSFs or prolonged survival in the absence of CSFs. Conditioned media and cell lysates from leukemic cell lines from 8 animals contained variable levels of GM-CSF or multi-CSF. Proliferation of a GM-CSF-producing cell line was inhibited by anti-GM-CSF antibody, while both the parental FDC-P1 line and a leukemic line secreting multi-CSF remained unaffected. The patterns of growth in vitro of the leukemic cells tended to correlate with the amounts of CSFs produced. The observations show that leukemic transformation of FDC-P1 cells in vivo is frequently linked to autogenous production of hemopoietic growth factors. The range of abnormal in vitro growth patterns observed includes those typical of human acute myeloid leukemia, and the in vivo transformation model may be useful in analyzing the mechanisms leading to the development of this human disease.

Animals↗
PubMed1984

[A new method for the evaluation of the success of anti-arrhythmic drug therapy and a paradoxical drug-induced arrhythmogenic effect in individual patients].

The aim of this study was to develop standards to define both antiarrhythmic drug efficacy and a drug-induced arrhytmogenic effect. In 45 patients with frequent and complex ventricular tachyarrhythmias 3 continuous 24-hour Holter recordings were performed. The spontaneous variability of ventricular premature beats and ventricular pairs was calculated using a new statistical method (transformation model). If two 24-hour Holter monitoring periods, one period before and the other with antiarrhythmic therapy, are compared, at least 75% reduction of ventricular premature beats and 90% reduction of ventricular pairs is necessary to be reasonably certain that one is measuring a drug response rather than spontaneous arrhythmia reduction (p less than or equal to 0.05). On the other hand, drug-induced aggravation can be assumed if ventricular premature beats and ventricular pairs have increased by more than 144% and 227%, respectively (p less than or equal to 0.05).

Anti-Arrhythmia Agents↗
PubMedDate not supplied

Osteosarcoma cells in tissue culture. III. Actin filament distribution.

Microfilaments, especially actin, have been demonstrated in a variety of noncontractile cells. In earlier studies, the quantity as well as the distribution of these microfilaments has been used to differentiate normal murine fibroblasts from virally transformed cells. This study examines these differences in cells from spontaneously occurring, human osteosarcomas and normal human fibroblasts by transmission election microscopy and heavy meromyosin (HMM) decoration. Both the tumor cells and the normal fibroblasts were found to have subcortical bands of 7-nm microfilaments that labelled with HMM and were 150-300 nm in thickness. There was a central reticular pattern of microfilaments predominantly composed of 7-nm filaments in the fibroblasts but with a larger proportion of 10-nm filaments in the osteosarcoma cells. Arrowhead formation was present after mild Triton X-100 extraction and HMM decoration on only the 7-nm microfilaments, in both types of cells. Differences in the quantity of 10-nm filaments between cells in culture from spontaneously occurring human sarcomas and normal fibroblasts may account for differential surface responses, e.g., contact inhibition and saturation density. Unlike some evidence from viral transformation models, the data from this study do not support the hypothesis that tumorgenicity is linked mechanistically to decreases in polymerized cellular actin, at least not in cells from spontaneously occurring human sarcomas. The cellular behavior of human sarcomas, both in vitro and in vivo, may be a manifestation of differences both in structural proteins and cell surface proteins.

Actins↗
PubMed2004

Spot shape modelling and data transformations for microarrays.

MOTIVATION: To study lowly expressed genes in microarray experiments, it is useful to increase the photometric gain in the scanning. However, a large gain may cause some pixels for highly expressed genes to become saturated. Spatial statistical models that model spot shapes on the pixel level may be used to infer information about the saturated pixel intensities. Other possible applications for spot shape models include data quality control and accurate determination of spot centres and spot diameters. RESULTS: Spatial statistical models for spotted microarrays are studied including pixel level transformations and spot shape models. The models are applied to a dataset from 50mer oligonucleotide microarrays with 452 selected Arabidopsis genes. Logarithmic, Box-Cox and inverse hyperbolic sine transformations are compared in combination with four spot shape models: a cylindric plateau shape, an isotropic Gaussian distribution and a difference of two-scaled Gaussian distribution suggested in the literature, as well as a proposed new polynomial-hyperbolic spot shape model. A substantial improvement is obtained for the dataset studied by the polynomial-hyperbolic spot shape model in combination with the Box-Cox transformation. The spatial statistical models are used to correct spot measurements with saturation by extrapolating the censored data. AVAILABILITY: Source code for R is available at http://www.matfys.kvl.dk/~ekstrom/spotshapes/

Algorithms↗
PubMed1986

A microcomputer algorithm for solving compartmental models involving radionuclide transformations.

An algorithm for solving first-order non-recycling compartment models is described. Given the initial amounts of a radioactive material in each compartment and the fundamental transfer rate constants between each compartment, the algorithm gives both the amount of material remaining at any time t and the integrated number of transformations that would occur up to time t. The method is analytical, and consequently, is ideally suited for implementation on a microcomputer. For a typical microcomputer with 64 kilobytes of random access memory, a model containing up to 100 compartments, with any number of interconnecting translocation routes, can be solved in a few seconds; providing that no recycling occurs. An example computer program, written in 30 lines of Microsoft BASIC, is included in an appendix to demonstrate the use of the algorithm. A detailed description is included to show how the algorithm is modified to satisfy the requirements commonly encountered in compartment modelling, for example, continuous intake, partitioning of activity, and transformations from radioactive progeny. Although the algorithm does not solve models involving recycling, it is often possible to represent such cases by a non-recycling model which is mathematically equivalent.

Computers↗
PubMed1992

Interpretation of linear regression models that include transformations or interaction terms.

In linear regression analyses, we must often transform the dependent variable to meet the statistical assumptions of normality, variance stability, or linearity. Transformations, however, can complicate the interpretation of results because they change the scale on which the dependent variable is measured. In this setting, the inclusion of product terms or the transformation of some independent (or predictor) variables may further complicate interpretation. In this article, we present some interpretations of linear models that include transformations or product terms. We illustrate these interpretations using regression analyses designed to study determinants of serum testosterone levels. These examples show how one can present results using simple measures, such as medians, and interpret regression parameters.

Epidemiologic Methods↗
PubMed2003

Estimating blood-brain barrier opening in a rat model of hemorrhagic transformation with Patlak plots of Gd-DTPA contrast-enhanced MRI.

Patlak plot processing of Gd-shifted T1 relaxation-time images from a rat model of hemorrhagic transformation yielded estimates and maps of the blood-to-brain influx rate constant of Gd-DTPA (K1). The Patlak plots also produced a heretofore unrecognized parameter, the distribution space of the intravascular-Gd-shifted protons (Vp), an index of blood-to-tissue transfer of water. The K1 values for Gd-DTPA were very high for the regions of blood-brain barrier (BBB) opening and were similar to those of 14C-sucrose concurrently obtained by quantitative autoradiographic (QAR) analysis. In these same ROI's, Vp was five-fold greater than normal, which suggests that the permeability of the BBB to water was also increased. The 14C-sucrose space of distribution in the ischemic ROI's was around 8%, thus indicating a sizable interstitial space. The spatial resolving power of Gd-DTPA-deltaT1 imaging was rather good, although no match for 14C-sucrose-QAR. This study shows that quantitative deltaT1-MRI estimates of regional blood-brain transfer constants of Gd-DTPA and water distribution are possible when Patlak plots are employed to process the data. This approach may be useful for tracking the time-course of BBB barrier function in both animals and humans.

Animals↗
PubMed2026

LAMBDA: a prophage detection benchmark for genomic language models.

Transformer-based genomic sequence models represent an emerging frontier in computational biology. Yet, their embeddings have not yet shown the same level of predictive power as natural and protein language models, highlighting a gap between current implementations and theoretical promise. Existing benchmarks for DNA language models primarily focus on classifying regulatory elements in eukaryotic genomes, leaving open the fundamental question of whether these models learn sequence-level features across whole genomes. We introduce LAMBDA, a benchmark designed to rigorously evaluate genome language model embeddings through phage-bacteria sequence discrimination across four categories of increasing complexity: probing tasks, fine-tuning assessments, diagnostic tests, and genome-wide prophage detection. Our comprehensive analysis of current genomic language models provides insight into the importance of training data selection relative to model size, the need for domain-specific training, and the capabilities and limitations of genomic language models for detecting prophage sequences. This benchmark represents a challenging genomic annotation task in the bacterial domain and addresses a key computational problem with direct relevance to microbiology and medicine.

Prophages↗
PubMed2026

LAMBDA: A Prophage Detection Benchmark for Genomic Language Models.

Transformer-based genomic sequence models represent an emerging frontier in computational biology. Yet, their embeddings have not yet shown the same level of predictive power as natural and protein language models, indicating a gap between current implementations and theoretical promise. Existing benchmarks for DNA language models primarily focus on classifying regulatory elements in eukaryotic genomes, leaving open the fundamental question of whether these models learn sequence-level features across whole genomes. We introduce LAMBDA, a benchmark designed to rigorously evaluate genome language model embeddings through phage-bacteria sequence discrimination across four categories of increasing complexity: probing tasks, fine-tuning assessments, diagnostic tests, and genome-wide prophage detection. Our comprehensive analysis of current genomic language models provides novel insights into the importance of training data quality relative to model size, the need for domain-specific training, and the application of genomic language models for detecting prophage sequences. This benchmark represents a challenging genomic annotation task in the bacterial domain and addresses a key computational problem with direct relevance to microbiology and medicine.

DNA language model↗
PubMed2000

Transforming growth factor beta3 promotes fascial wound healing in a new animal model.

HYPOTHESIS: Transforming growth factor beta(3) (TGF-beta(3)) promotes fascial wound healing in a new animal model, as measured by wound breaking strength, collagen deposition, and cellular proliferation. DESIGN/INTERVENTION: Bilateral, longitudinal incisions were made in the anterior rectus sheaths of 24 male New Zealand white rabbits. One incision was treated with 1 microg of TGF-beta(3); the contralateral incision served as a control. The wounds were harvested at 1, 2, 3, 4, 6, and 8 weeks after creation ("wounding"). MAIN OUTCOME MEASURES: Wound tissue was tested for breaking strength using a tensiometer and processed for histological examination of collagen deposition and cellular proliferation at all time points after wounding. Collagen deposition and cellular proliferation were measured in histological cross sections of wounds with Masson trichrome staining and proliferating cell nuclear antigen immunohistochemistry, respectively. RESULTS: At all time points after wounding, treatment with TGF-beta(3) significantly increased the wound breaking strength (up to 138%) and collagen deposition (up to 150%) over the control group. Cellular proliferation was increased during the first 3 weeks after wounding (up to 147%), but returned to baseline levels by the fourth week. CONCLUSIONS: Transforming growth factor beta(3) promotes fascial wound healing. In this new animal model of fascial wound healing, TGF-beta(3) increased fascia breaking strength, collagen deposition, and cellular proliferation. These results are similar to findings in cutaneous wound models and demonstrate, for the first time, a pharmacologic agent to accelerate fascial healing.

Animals↗