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At least 703 records · Page 39Linked to original sources
PubMed2005

A dual optimization method for the material parameter identification of a biphasic poroviscoelastic hydrogel: Potential application to hypercompliant soft tissues.

A dual-indentation creep and stress relaxation methodology was developed and validated for the material characterization of very soft biological tissue within the framework of the biphasic poroviscoelastic (BPVE) constitutive model. Agarose hydrogel, a generic porous medium with mobile fluid, served as a mechanical tissue analogue for validation of the experimental procedure. Indentation creep and stress relaxation tests with a solid plane-ended cylindrical indenter were performed at identical sites on a gel sample with dimensions large enough with respect to indenter size in order to satisfy an infinite layer assumption. A finite element (FE) formulation coupled to a global optimization algorithm was utilized to simultaneously curve-fit the creep and stress relaxation data and extract the BPVE model parameters for the agarose gel. A numerical analysis with artificial data was conducted to validate the uniqueness of the computational procedure. The BPVE model was able to successfully cross-predict both creep and stress relaxation behavior for each pair of experiments with a single unique set of material parameters. Optimized elastic moduli were consistent with those reported in the literature for agarose gel. With the incorporation of appropriately-sized indenters to satisfy more stringent geometric constraints, this simple yet powerful indentation methodology can provide a straightforward means by which to obtain the BPVE model parameters of biological soft tissues that are difficult to manipulate (such as brain and adipose) while maintaining a realistic in situ loading environment.

Connective Tissue↗
PubMed1988

[Percutaneous biopsy (PB) of solid thoraco-abdominal formations with instrumental guidance. The authors' experience].

The results are reported of 283 percutaneous biopsies performed on solid thoracic and abdominal masses. Indications to biopsy are examined at first, which are relatively limited in number if compared to other authors' opinion on the subject--i.e., when the tumor cannot be characterized with any other methodology, or in case of neoplasms whose histological type is to be known in order to plan therapy. The techniques employed are then evaluated, with a special emphasis on the needle caliber and the guidance method (US, radioscopy and CT). Correct samplings have been obtained in more than 90% of cases. Minor complications were observed in less than 10% of cases, while major complications were totally absent. In conclusion, percutaneous biopsy proves useful in those cases where exam indication is respected and an accurate selection is previously performed.

Abdomen↗
PubMed2006

Rank-statistics based enrichment-site prediction algorithm developed for chromatin immunoprecipitation on chip experiments.

BACKGROUND: High density oligonucleotide tiling arrays are an effective and powerful platform for conducting unbiased genome-wide studies. The ab initio probe selection method employed in tiling arrays is unbiased, and thus ensures consistent sampling across coding and non-coding regions of the genome. Tiling arrays are increasingly used in chromatin immunoprecipitation (IP) experiments (ChIP on chip). ChIP on chip facilitates the generation of genome-wide maps of in-vivo interactions between DNA-associated proteins including transcription factors and DNA. Analysis of the hybridization of an immunoprecipitated sample to a tiling array facilitates the identification of ChIP-enriched segments of the genome. These enriched segments are putative targets of antibody assayable regulatory elements. The enrichment response is not ubiquitous across the genome. Typically 5 to 10% of tiled probes manifest some significant enrichment. Depending upon the factor being studied, this response can drop to less than 1%. The detection and assessment of significance for interactions that emanate from non-canonical and/or un-annotated regions of the genome is especially challenging. This is the motivation behind the proposed algorithm. RESULTS: We have proposed a novel rank and replicate statistics-based methodology for identifying and ascribing statistical confidence to regions of ChIP-enrichment. The algorithm is optimized for identification of sites that manifest low levels of enrichment but are true positives, as validated by alternative biochemical experiments. Although the method is described here in the context of ChIP on chip experiments, it can be generalized to any treatment-control experimental design. The results of the algorithm show a high degree of concordance with independent biochemical validation methods. The sensitivity and specificity of the algorithm have been characterized via quantitative PCR and independent computational approaches. CONCLUSION: The algorithm ranks all enrichment sites based on their intra-replicate ranks and inter-replicate rank consistency. Following the ranking, the method allows segmentation of sites based on a meta p-value, a composite array signal enrichment criterion, or a composite of these two measures. The sensitivities obtained subsequent to the segmentation of data using a meta p-value of 10-5, an array signal enrichment of 0.2 and a composite of these two values are 88%, 87% and 95%, respectively.

Algorithms↗
PubMed2001

[Living the inexorability of time and its changes with losses and possibilities: women in climacteric].

This research deals with the experience of women in climacterium. Symbolic interactionism and Grounded Theory were the theoretical and methodological framework of the study. Its objectives were to understand: how the experience of the climacterium is defined by the women; what were the psychosocial processes of interaction lived by the women; and to develop a theoretical model representing the experience of the women in climacterium. The strategies used to collect the data were participant observation and open ended interviews. The subjects were women in the age group of 45 to 60. The sample was of 30 women. The study revealed that the climacterium experience may be constituted of two phenomena: REJECTING CHANGES which is characterized by the women as a moment of loss and TRYING TO COPE WITH CHANGES, which represents the moment construction of new concepts with possibilities of reconstruction of life. Supported by these two phenomena, the central category was generated: LIVING THE INEXORABILITY OF TIME AND ITS CHANGES WITH LOSSES AND POSSIBILITIES which is fundamental to the generation of the theoretical model representing the experience of women in climacterium.

Climacteric↗
PubMed2006

Nursing advocacy: how is it defined by patients and nurses, what does it involve and how is it experienced?

UNLABELLED: THE STUDY'S RATIONALE: Advocacy is an integral part of nursing. However, there is a scarcity of empirical evidence on nursing advocacy process and most of that evidence concerns nurses' views on the care of certain vulnerable patient groups in acute care settings. Before nursing practice can truly adopt advocacy as an inherent and natural part of nursing, a clearer understanding is needed of how it is defined and what activities are needed to accomplish advocacy. AIMS AND OBJECTIVES: The aim was to describe the way that nursing advocacy is defined, the activities through which nursing advocacy is accomplished and the way that nursing advocacy is experienced by patients and nurses. METHODOLOGICAL DESIGN AND JUSTIFICATION: Based on a qualitative approach, the study was limited to adult patients experiencing procedural pain in somatic care. Interviews were conducted in a convenience sample of patients (n = 22) and nurses (n = 21) from four medical and four surgical wards in Finland. A qualitative content analysis of the tape-recorded data was then carried out. ETHICAL ISSUES AND APPROVAL: The appropriate ethical principles were followed. All the participants gave their informed consent and formal approval for conducting the research was obtained according to national and local directives. RESULTS: Nursing advocacy seems to integrate aspects of individuality, professionalism and experiences of empowering, exceptional care. It is not a single event, but a process of analysing, counselling, responding, shielding and whistleblowing activities in clinical nursing practice. CONCLUSIONS: In nursing practice the abstract concept of nursing advocacy finds expression in voicing responsiveness, which integrates an acknowledged professional responsibility for and active involvement in supporting patients' needs and wishes.

Adult↗
PubMed2005

Flow-injection enzymatic analysis for glycerol and triacylglycerol.

A flow-injection enzymatic analytical system was developed for determination of glycerol and triacylglycerol based on enzymatic reactions in capillary followed by electrochemical detection. The hydrogen peroxide produced from the enzyme reaction was monitored by a platinum-based electrochemical probe. Different immobilization strategies on silica support were studied. The best and most effective configuration found for the measurement of glycerol and triacylglycerols in this system was the tandem connection of a lipase column and a silica-fused capillary column coimmobilized with glycerokinase (GK) and glycerol-3-phosphate oxidase (GPO). Lipase helps the breakdown of triacylglycerol to yield free fatty acids and glycerol, while glycerokinase catalyzes the adenosine-5-triphosphate-dependent phosphorylation of glycerol to yield alpha-glycerol phosphate, which can subsequently be oxidized by 3-glycerol phosphate oxidase to produce hydrogen peroxide. Response-surface methodology (RSM) was applied to optimize the proposed system for glycerol. Experiment settings were designed by central composite design to investigate the combined effects of pH, flow rate, reaction temperature, and ATP concentration on collected signals. The fitted model, per RSM, showed that the optimum conditions of the system are 2 mM ATP in 0.1 M carbonate buffer (pH 11.0), flow rate of 0.18 mL/min, temperature of 35 degrees C, 20 microL of sample injection, and applied voltage of 0.650 V. The proposed biosensing system using lipase, GK, and GPO exhibited a flow-injection analysis peak response of 2.5 min and a detection limit of 5 x 10(-5) M glycerol (S/N = 3) with acceptable reproducibility (CV < 4.30%). It also had linear working ranges from 10(-4) to 10(-2) M for glycerol and from 10(-3) to 10(-2) M for triacylglycerol. The capillary enzyme reactor was stable up to 2 months in continuous operation, and it was possible to analyze up to 15 samples per hour. The present biosensing system holds promise for on-line detection of triacylglycerol in serum and glycerol content in fermented products.

Biosensing Techniques↗
PubMed2004

Methodological issues in public reporting of patient perspectives on hospital quality.

BACKGROUND: Increasing attention is being focused on public reporting of patient satisfaction and experience with hospital care, both nationally and at the state level. Comparative reports on hospital patient satisfaction use a standard survey, but little is known about underlying methodological approaches for reporting these quality measures. METHODS: Literature, Web sites, and key informants were used to identify nine public reports. In-depth reviews were conducted to determine approaches to collecting, analyzing, and publicly reporting comparative data. Data were grouped into four analytic categories: survey, sampling, computation of scores, and reporting of scores. RESULTS: The reports were similar in response rates and sampling procedures but differed in the number of hospitals included, the survey instrument, and survey procedure. The reports varied considerably in the techniques for computing hospital scores and decisions about reporting scores. CONCLUSIONS: Reports from nine locales illustrate the decision making necessary to produce comparative reports on hospital patient satisfaction. Differences stem from decisions about the survey instrument and statistical decisions about how to interpret and report data. These issues should be clearly delineated as part of any public reporting process.

Benchmarking↗
PubMed2001

Expression of results with uncertainty for the determination of pesticides in melon--experience in a proficiency test.

The expression of results with an uncertainty through the "bottom-up" approach, involving the estimation and combination of all the sources of uncertainty, represents a challenge when the analytical method includes mass transfer steps (MTS). These steps (e.g. extraction, evaporation, digestion, etc.) with inherently different from 100% recoveries lack models capable of describing their precision and efficiency. Recently, a new methodology was published aimed at the estimation of the performance of these critical steps. Comparison of the experimental dispersion from the replicated analysis of spiked samples with the combination of the uncertainty associated with gravimetric, volumetric and instrumental quantification steps (described by well established models) allows the estimation of the MTS uncertainty. Evaluation of the behaviour of the MTS within the analytical range supports the use of developed estimations over a wide concentration range. This methodology was applied, with success, to the determination of pesticide residues in melon in one particular proficiency test organised by the Food Analysis Performance Assessment Scheme (FAPAS) between November 2000 and February 2001.

Chromatography, Gas↗
PubMed2006

Content analysis of free-response narratives to personal meanings of death among Chinese children and adolescents.

The study explores development of the concept of death among 204 Chinese children and adolescents and analyzes the relationships between death concept development and background variables. A coding manual for content analysis of death constructs adapted from R. A. Neimeyer et al. (1983) was used to classify each construct in the paragraphs written by participants regarding their views of death. The 6 categories most frequently identified were Internal Causality, Negative Emotion State, External Causality, Nonexistence, Negative Body State, and Existence. Death-related experiences did not significantly influence concepts regarding death, while significant differences emerged as a function of grade, gender, religion, and family death discussion for several death constructs. Compared with earlier American samples, Chinese children and adolescents identified less with choice and purposeful death constructs and were less likely to view death in terms of personal choice and morals or in terms of psychological or natural meaning. Whether the differences were due to cultural, methodological or age factors deserves further study. Finally, this study concludes with some recommendations for the future study of death constructs.

Adolescent↗
PubMed2002

Issues of race, ethnicity, and culture in caregiving research: a 20-year review (1980-2000).

PURPOSE: The goals of this review are to synthesize what is known about caregiving among diverse groups and to identify gaps in knowledge to guide future research on caregiving. The review focuses on conceptual and theoretical approaches, sampling strategies, measurement techniques, and similarities and differences found among groups and across studies. DESIGN AND METHODS: A narrative approach was used to review 59 articles published between 1980 and 2000, with particular attention to race, ethnicity, and/or culture. Primary sources of relevant articles included electronic databases, other review articles, and reference lists. RESULTS: Caregiving experiences and outcomes varied across racial and ethnic groups. However, the use of nontheoretical approaches, nonprobability samples, and inconsistent measures among studies has limited understanding of caregiving among diverse populations. IMPLICATIONS: It is important that conceptualization and theorizing broaden with increasing numbers of studies that include diverse groups. Future caregiving research needs to give more attention to such issues as acculturation, assimilation, and cultural values, beliefs, and norms, while also improving theoretical and methodological rigor.

Caregivers↗
PubMed2026

Benchmarking computational decontamination of ambient RNA.

Gene expression profiling of single cells using single-cell and single-nucleus RNA sequencing (sxRNA-seq) enables researchers to characterize cellular heterogeneity and unraveling complex biological processes at unprecedented resolution. However, sxRNA-seq faces challenges due to the presence of ambient RNA, extraneous RNA molecules not originating from the cells of interest. Sample preparation is a major source of ambient RNA, where harsh conditions can lead to cell lysis and the release of intracellular RNA. This inescapable inclusion of ambient RNA can cause erroneous results and hinder downstream analyses. To address this issue, various methodologies have been developed to identify, quantify, and remove ambient RNA. Here, we rigorously evaluate 7 state-of-the-art methodologies for ambient RNA removal using simulated datasets, species-mixing experiments of varying complexities, and genotype-mixing experiments. We find that no single method performs the best across all datasets and metrics, but CellBender, DecontX and SoupX generally perform well.

ambient RNA↗
PubMed1995

Rotavirus quantification: a comparison between the enumerative and the MPN techniques.

A commonly used technique to isolate rotaviruses from a water environment involves the inoculation on cell culture associated with the revelation of the viral multiplication by indirect immunofluorescence. The results of the experiment using this methodology may be expressed either with an enumerative technique or with a MPN technique. We have found that the enumerative method provided the highest yield as opposed to the MPN method by a ratio close to 3.7. According to the experimental conditions that were used, the enumerative method should be favored for the detection of viruses from a medium with low viral density or when quantifying viruses from a given sample. This work involves a comparative study where the MPN method is very attractive because of the ease of implementation and the rapidity with which results may be obtained.

Analysis of Variance↗
PubMed2005

Bioaerosol emission rate and plume characteristics during land application of liquid class B biosolids.

This study investigated bioaerosol emission rates and plume characteristics of bioaerosols generated during land application of liquid Class B biosolids. In addition, it compared the rate of aerosolization of coliphages and total coliform bacteria during land application of liquid Class B biosolids to the rate of aerosolization during land application of groundwater inoculated with similar concentrations of Escherichia coli and coliphage MS2. Air samples were taken immediately downwind of a spray applicator as it applied liquid (approximately 8% solids) biosolids to farmland near Tucson, Arizona. Air samples were also collected immediately downwind of groundwater seeded with MS2 and E. coli applied to land in an identical manner. Air samples, collected with liquid impingers, were taken in horizontal and vertical alignment with respect to the passing spray applicator. Vertical and horizontal sample arrays made it possible to calculate the flux of microorganisms through a virtual plane of air samplers, located 2 m downwind of the passing spray applicator. Neither coliphages nor coliform bacteria were detected in air downwind of spray application of liquid Class B biosolids. Based on limits of detection for the methodology, the rate of aerosolization during land application of liquid biosolids was calculated to be less than 33 plaque forming units (PFU) of coliphage and 10 colony forming units (CFU) of coliform bacteria per meter traveled by the spray applicator. The rate of aerosolization during land application of seeded groundwater was found to be, on average, 2.02 x 10(3) CFU E. coli and 3.86 x 10(3) PFU MS2 aerosolized per meter traveled by the spray applicator. This is greater aerosolization than was observed during land application of biosolids. Because concentrations of coliphages and coliforms were similar in the liquid biosolids and the seeded water, itwas concluded that some property of biosolids reduces aerosolization of microorganisms relative to groundwater. Additional experiments utilizing a novel air sampling protocol showed that the duration of bioaerosol exposure immediately (2 m) downwind of biosolids spray application is brief and the plume of bioaerosols generated is discrete. Additional air samples showed that aerosolization of coliphages and coliform bacteria after liquid biosolids have been applied to land does not occur at detectable levels.

Aerosols↗
PubMed1981

Use of stable isotopes of selenium in human metabolic studies: development of analytical methodology.

Use of stable isotopes of selenium in relation to enrichment of diets for studies of selenium absorption and metabolism in human subjects is discussed. A method based on radiochemical neutron activation analysis is described which allows accurate measurement of stable isotopes 74Se, 76Se, and 80Se in matrices (feces, plasma, red blood cells, and urine) of interest in metabolic studies. We show that these isotopes can routinely be measured with analytical precision and accuracy of 10% in samples of available size. This precision and accuracy is satisfactory for conduct of many nutritional experiments concerned with gastrointestinal absorption, plasma and red cell selenium turnover, and urinary excretion of the element, using an oral dose of 74Se. Original, experimental data are presented to illustrate the degree of enrichment of 74Se in feces, plasma, and urine after a single oral ingestion of 50 micrograms of the isotope with a breakfast meal in healthy young men.

Absorption↗
PubMed2001

Species-specific isotope-ratio measurements of volatile tin and antimony compounds using capillary GC-ICP-time-of-flight MS.

The analytical performance of an axial inductively-coupled-plasma time-of-flight mass spectrometer (ICP-TOFMS) as a detector for fast transient chromatographic signals resulting from the coupling to capillary gas chromatography (CGC) was investigated. A cryotrapping GC-ICP-TOFMS method for the determination of volatile metal(loid) compounds (VOMs) in gases was used and the suitability of the TOF mass analyzer for multielemental speciation analysis and multi-isotope ratio determinations was studied in terms of accuracy and precision. Isotope ratios 118Sn/120Sn and 121Sb/123Sb have been determined in in-house gas standard atmospheres in Tedlar bags at two different levels (100 pg and 1 ng) for different elemental species (SnH4, MeSnH3, Me2SnH2, Me3SnH, BuSnH3, SbH3, and MeSbH2). A limitation arising from counting statistics in both detection modes could be shown. A solution containing rhodium (10 ng mL(-1)) and cadmium (40 ng mL(-1)) was introduced simultaneously to the GC outlet. Rhodium acts as a continuous internal standard and Cd is used for mass-bias correction (by measuring the 111Cd/113Cd ratio). The detection system in both pulse counting and analog mode was examined. The best attainable precision was established for Me2SnH2 (analog mode, 12 replicates, 1 ng, RSD 0.34%, accuracy 0.31%) whereas most other species ranged between 0.4 and 0.5% RSD if higher concentrations were used. The limitations of the pulse counting system are clearly seen, with peak heights of more than 2000 counts reaching saturation (for an integration time of 100 ms), which reduces the accuracy of isotope ratio determinations. A dozen VOM could be detected in an aged landfill gas sample; several unidentified Sn compounds were present. Although their isotope ratios are within the confidence value of the standards, it is not yet clear if the acquired precision is good enough to identify isotopic fractionation of metal(loid)s through biovolatilization processes. With the precision achieved, the combination of cryotrapping GC and ICP-TOFMS is a powerful tool for monitoring volatile multi-element species in multi-tracer experiments and isotope dilution methodology.

Antimony↗
PubMed1985

An improved bioassay method for determining natriuretic activity of atrial extracts.

Extracts of mammalian atrial tissue contain potent natriuretic substances known collectively as atrial natriuretic factor (ANF). The purposes of the present experiments were: 1) to improve on existing bioassay methodology for the detection of ANF activity in atrial extracts, and 2) to compare the ANF activity of atrial extracts prepared from Brattleboro-stain diabetes insipidus (DI) rats with that from normal and water-deprived Long-Evans (LE) rats. A pool of atrial tissue extract (AE) was prepared from normal Sprague-Dawley rats for use as a standard against which unknown AE samples could be compared. Five doses, ranging from 27 to 432 micrograms of AE protein, were assayed in the Sprague-Dawley bioassay rats. Phosphate-buffered saline (PBS) vehicle and ventricular tissue extracts were also assayed. Statistical analysis of several log dose-response relationships revealed that the bioassay response most appropriate in determining relative natriuretic activity of AE was the log of the experimental/control ratio for sodium excretion. The bioassay was used to demonstrate that PBS atrial extracts from both water-deprived LE rats and DI rats contain more natriuretic activity than do PBS atrial extracts from LE rats.

Animals↗
PubMed1993

A Delphi study of pediatric oncology nurses' facilitative behaviors.

Using a classic Delphi methodology, this study identified the nursing behaviors and interventions that oncology nurses rated as most important in facilitating the patient's, parents', and siblings' coping efforts with the effects of disease and treatment. Random selection of 300 pediatric oncology nurses resulted in a final sample of 69 nurses who completed all 3 rounds of the Delphi. The majority of the nurses were younger than 35 years of age, had less than 10 years of experience, were educated with at least a bachelor's degree, and practiced in an all-oncology setting. Twenty-eight facilitative behaviors were identified for the child with cancer, 25 for the parents, and 25 for the siblings. Results of this study support previous research on patient, parent, and sibling coping.

Adaptation, Psychological↗
PubMed2004

A new in vivo interdental sampling method comparing a daily flossing regime versus a manual brush control.

OBJECTIVE: The impact of flossing the interdental space is typically assessed by visual methods of questionable reliability, such as clinician observations and evaluations for scoring of plaque on visual tooth surfaces. The objective of this study was to develop and validate a method to measure interproximal quantities of dental plaque, thereby permitting quantitative evaluations of between-teeth cleaning and biofilm removal. METHODOLOGY: Laboratory studies were performed correlating the quantity of bacteria to the amount of measured protein in a sample using a standardized protein assay (Bio-Rad Protein Assay) and samples containing single bacterial species and saliva/bacterial pellets. Analysis of the plaque was standardized against a bovine serum albumin (BSA) control. Pilot studies helped develop a technique for hygienist-applied interproximal flossing, reducing contamination from saliva and other possible sources of indeterminate error. Repeated sampling experiments were carried out to optimize the technique needed to remove the majority of quantifiable plaque, the best choice of flossing material, and establish the technique for collection. A pilot clinical trial assessed the benefits of daily flossing in reducing measurable quantities of interproximal plaque using the developed method. Thirty-nine subjects had six interdental sites (distributed across all four quadrants, pre-molar and molar boundaries) sampled on either side, over a three-week treatment period, in two balanced and equally sized treatment groups, with twice-daily manual brushing with or without daily flossing. RESULTS: Laboratory studies confirmed the accuracy of the protein detection kit in assaying bacterial plaque loads from single species or complex biofilms. In pilot developmental screens, single flossing sweeps with appropriate dental floss were sufficient to remove the majority of quantifiable biomass from interproximal sites. The clinical study demonstrated that after three weeks, interdental plaque in floss users was significantly reduced versus baseline scores. Non-floss users showed no significant reduction. In direct comparison, less interdental plaque was recovered from subjects who had followed a daily flossing regime compared to subjects who had used a manual toothbrush alone (p = 0.0866). CONCLUSION: The sampling method quantified the cleaning effects of daily flossing on interproximal plaque levels. Daily flossing significantly reduced the amount of plaque found between the teeth compared to a manual brushing regimen alone. This new method should be useful in future studies on the evaluation of mechanical or chemical means of interproximal plaque control.

Adult↗