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Results for “data reproducibility”

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At least 865 records · Page 48Linked to original sources
PubMed1983

Algorithm-directed care by nonphysician practitioners in a pediatric population: Part I. Adherence to algorithm logic and reproducibility of nonphysician practitioner data-gathering behavior.

The ability of quickly trained nonphysician practitioners to care for pediatric patients with upper respiratory tract infections (URIs) was evaluated in 3802 patients. These nonphysician practitioners (Army Pamosists) used an explicit treatment protocol and computerized audit of protocol adherence. Pamosists omitted protocol-suggested plans in 3.7 per cent of cases and ordered unnecessary treatment plans in 1.7 per cent of cases. They did not obtain a suggested MD consultation in 6.2 per cent of the cases. Agreement between Pamosists and pediatricians on data and management decisions (PM-MD study) was then compared with agreement on the same variables between pairs of a group of five pediatricians who saw a separate but comparable group of 103 pediatric URI patients (MD-MD study). The Pamosists demonstrated good (77 to 89 per cent) overall agreement with pediatricians, and the amounts of agreement between Pamosists and pediatricians in the PM-MD study did not generally differ significantly (p greater than 0.05) from the agreement on the same variables between pairs of pediatricians in the MD-MD study.

Allied Health Personnel↗
PubMed1993

Quantitating cataract and nuclear brunescence, the Harvard and LOCS systems.

Subjective and objective systems are used to quantify cataract at The Center for Clinical Cataract Research. We have described each system and its use, presented data on reproducibility and validity, and for objective systems, demonstrated the correlation to the subjective grade of the cataract as defined by the Lens Opacities Classification Systems, Versions II and III (LOCS II and III). The subjective systems are used to classify nuclear color, nuclear opalescence, cortical cataract, and posterior subcapsular cataract. Reported kappa scores for LOCS II range from 0.85 to 1.0. Intraclass correlation coefficients for LOCS III (r1) range from 0.67 to 0.94. The computerized objective system are: (1) fast spectral scanning colorimetry (FSSC) for assessment of nuclear color (r1 = 0.96 to 0.98); (2) nuclear mean density (NMD) for assessment of nuclear opalescence (r1 = 0.97); and (3) percent area opacity (anterior = a; posterior = p) (OPAC-a and OPAC-p) for assessment of cortical and posterior subcapsular cataract (r1 = 0.92 to 0.96).

Adult↗
PubMed2005

Beta-hydroxy-beta-Methylbutyrate and its use in athletics.

Nutritional supplements are widely used by patients and athletes around the world for many different reasons. Many companies are thriving on this billion-dollar industry with little proof that these substances do what they are reported or suggested to do. Beta-hydroxy-beta-methylbutyrate (HMB) is a relatively new supplement on the ergogenic landscape. Studies of HMB supplementation have shown minimal gains in strength and lean body mass in specific populations, mainly untrained athletes and patients with wasting syndromes. HMB use in those athletes involved in regular high-intensity exercise has not been proven to be beneficial when multiple variables are evaluated. Unlike other ergogenics, with HMB no adverse events have been reported in association with short-term use. Despite these findings, HMB cannot be recommended as an ergogenic until further studies in larger groups reproduce early data. This review summarizes current literature on HMB, and provides the reader with information to better educate and treat patients and athletes.

Adult↗
PubMed2004

Evaluation of minimally invasive analysis system for cough leak point pressure measurement.

PURPOSE: Leak point pressure (LPP) measurement has become standard in the diagnosis of stress urinary incontinence. Leak point pressure is determined by increasing abdominal pressure, which can be done with a Valsalva maneuver or coughing, that is Valsalva LPP and cough LPP (CLPP). It may be influenced by catheter size, bladder volume and interobserver variability. A new, computerized LPP measuring technique for routine use in daily urodynamic practice was tested at a female unit urodynamic practice to evaluate female urinary incontinence. MATERIALS AND METHODS: A total of 28 female patients with a mean age of 54.07 years (range 23 to 82) and urinary incontinence underwent a new, minimally invasive measurement of the cough leak point. Measurements are made with the patient standing and repeated 3 times per patient. Additionally, parameters of the corresponding leak were recorded simultaneously. All patients underwent new CLPP measurement and a standard, complete urodynamic investigation, including filling cystometry with abdominal LPP and urethral pressure profile at rest. Statistical evaluation was done by linear regression analysis and the correlation coefficients among CLPP, age, standard abdominal LPP and maximum urethral pressure, and among the 3 measurements for each patient. RESULTS: : The assignment of leakage to the pressure signal presented no problem. All CLPP data were reproducible in the 3 repeated measurements per patient. No correlation was seen between CLPP and abdominal LPP or the urethral pressure profile. CONCLUSIONS: The study confirm that the CLPP is a practicable, consistent and minimally invasive method in routine use. Clinical use is easy and reproducible, and only 1 catheter is required for measurement.

Abdomen↗
PubMed2005

Endoscopic extraperitoneal radical prostatectomy: oncological and functional results after 700 procedures.

PURPOSE: We review our experience with endoscopic (totally) extraperitoneal radical prostatectomy (EERPE) as first line therapy for localized prostate cancer. MATERIALS AND METHODS: A total of 700 consecutive patients underwent EERPE. Mean patient age was 63.4 years (range 42 to 77). Mean preoperative prostate specific antigen was 10.7 ng/ml (range 1.4 to 82). A total of 206 patients (29.4%) had a history of previous lower abdominal or pelvic surgery including inguinal hernioplasty with mesh placement and 43 patients (6.1%) had a history of prostatic intervention (transurethral resection of the prostate, high intensity focused ultrasound, Millin prostatectomy, radiotherapy). After preparation of the preperitoneal space the technique of EERPE duplicates the steps of classic open descending retropubic radical prostatectomy including a nerve sparing EERPE when indicated. RESULTS: Mean operative time was 151 minutes (range 50 to 320). There was no conversion and the transfusion rate was 0.9% in 6. Four patients (0.6%) had intraoperative rectal injuries which were treated endoscopically with a 2-layer suture. A total of 14 patients (2%) required early and 3 patients (0.4%) required late postoperative reintervention. Pathological stage was pT2a in 89 patients (12.7%), pT2b in 54 (7.7%), pT2c in 245 (35%), pT3a in 229 (32.7%), pT3b in 79 (11.2%) and pT4 in 4 patients (0.6%). Positive surgical margins were found in 10.8% (42 of 388) of patients with a pT2 tumor and in 31.2% (96 of 308) of patients with a pT3 tumor. Pelvic lymph node dissection was performed in 266 patients (38%), of whom 14 (5.3%) were found to have lymph node involvement. Mean catheterization time was 6.2 days. Six months after surgery 83.8% of the patients were completely continent, 10.4% needed 1 to 2 pads daily and 5.8% of patients needed more than 2 pads daily. Of all patients who underwent nerve sparing procedures, 100 patients had a postoperative followup of 6 months. Of the 66 patients with the unilateral nerve sparing approach 8 (12.1%) had erections sufficient for intercourse and 16 of 34 patients (47.1%) with the bilateral nerve sparing procedure had erections sufficient for intercourse with or without the help of phosphodiesterase type 5 inhibitors. CONCLUSIONS: The results of this series are promising. Perioperative morbidity is low, and short-term oncological and functional results are favorable. Although the followup is too short to draw definite conclusions, it is obvious that a nerve sparing approach in EERPE is feasible and reproducible. Our data demonstrate that EERPE can be performed with equal efficacy and results compared with laparoscopic transperitoneal radical prostatectomy, while providing the ease and safety of a totally extraperitoneal approach, completely avoiding intraperitoneal complications.

Adult↗
PubMed2000

The 10q25 neocentromere and its inactive progenitor have identical primary nucleotide sequence: further evidence for epigenetic modification.

We have previously localized the core centromere protein-binding domain of a 10q25.2-derived neocentromere to an 80-kb genomic region. Detailed analysis has indicated that the 80-kb neocentromere (NC) DNA has a similar overall organization to the corresponding region on a normal chromosome 10 (HC) DNA, derived from a genetically unrelated CEPH individual. Here we report sequencing of the HC DNA and its comparison to the NC sequence. Single-base differences were observed at a maximum rate of 4.6 per kb; however, no deletions, insertions, or other structural rearrangements were detected. To investigate whether the observed changes, or subsets of these, might be de novo mutations involved in neocentromerization (i.e., in committing a region of a chromosome to neocentromere formation), the progenitor DNA (PnC) from which the NC DNA descended, was cloned and sequenced. Direct comparison of the PnC and NC sequences revealed 100% identity, suggesting that the differences between NC and HC DNA are single nucleotide polymorphisms (SNPs) and that formation of the 10q25.2 NC did not involve a change in DNA sequence in the core centromere protein-binding NC region. This is the first study in which a cloned NC DNA has been compared directly with its inactive progenitor DNA at the primary sequence level. The results form the basis for future sequence comparison outside the core protein-binding domain, and provide direct support for the involvement of an epigenetic mechanism in neocentromerization.

Alleles↗
PubMed2000

An ordered comparative map of the cattle and human genomes.

A cattle-human whole-genome comparative map was constructed using parallel radiation hybrid (RH) mapping in conjunction with EST sequencing, database mining for unmapped cattle genes, and a predictive bioinformatics approach (COMPASS) for targeting specific homologous regions. A total of 768 genes were placed on the RH map in addition to 319 microsatellites used as anchor markers. Of these, 638 had human orthologs with mapping data, thus permitting construction of an ordered comparative map. The large number of ordered loci revealed > or =105 conserved segments between the two genomes. The comparative map suggests that 41 translocation events, a minimum of 54 internal rearrangements, and repositioning of all but one centromere can account for the observed organizations of the cattle and human genomes. In addition, the COMPASS in silico mapping tool was shown to be 95% accurate in its ability to predict cattle chromosome location from random sequence data, demonstrating this tool to be valuable for efficient targeting of specific regions for detailed mapping. The comparative map generated will be a cornerstone for elucidating mammalian chromosome phylogeny and the identification of genes of agricultural importance."Ought we, for instance, to begin by discussing each separate species-in virtue of some common element of their nature, and proceed from this as a basis for the consideration of them separately?" from Aristotle, On the Parts of Animals, 350 B.C.E.

Animals↗
PubMed1999

Toward real-world sequencing by microdevice electrophoresis.

We report results using a microdevice for DNA sequencing using samples from chromosome 17, obtained from the Whitehead Institute Center for Genome Research (WICGR) production line. The device had an effective separation distance of 11.5 cm and a lithographically defined injection width of 150 microm. The four-color raw data were processed, base-called by the sequencing software Trout, and compared to the corresponding ABI 377 sequence from WICGR. With a criteria of 99% accuracy, we achieved average continuous reads of 505 bases in 27 min with 3% linear polyacrylamide (LPA) at 150 V/cm, and 460 bases in 22 min with 4% LPA at 200 V/cm at a temperature of 45 degrees C. In the best case, up to 565 bases could be base-called with the same accuracy in <25 min. In some instances, Trout allowed for accurate base-calling down to a resolution R as low as R = 0.35. This may be due in part to the high signal-to-noise ratio of the microdevice. Unlike many results reported on capillary machines, no additional sample cleanup other than ethanol precipitation was required. In addition, DNA fragment biasing (i.e., discrimination against larger fragments) was reduced significantly through the unique sample injection mechanism of the microfabricated device. This led to increased signal strength for long fragments, which is of great importance for the high performance of the microdevice.

Base Sequence↗
PubMed2003

Information flow dynamics and timing patterns in the arrival of email viruses.

Analysis of the timing of the arrival of email viruses at different computers provides a way of probing the structural and dynamical properties of the Internet. We found that the intervals t between the arrival of four different strains of email viruses have a power law distribution proportional to t(-d), where 1.5<or=d<or=3.2 and that there are positive correlations between these intervals. Salient features of the data were reproduced with a model having subnetwork units of different size where the structural components and the dynamical components all have power law scaling relationships with the size of the units. This is an assumption, that we hope will encourage empirical evaluation of these relationships.

Journal Article↗
PubMed2004

Nonlinear theory of pattern formation in ferrofluid films at high field strengths.

When a magnetic field is applied to a thin layer of a suspension of magnetic nanoparticles (ferrofluid), the formation of labyrinthine and hexagonal patterns is observed. We introduce a theory to describe ferrofluid patterns at high field, where a nonlinear relationship between field and magnetization is expected. The computational difficulties due to the use of a nonlinear magnetization curve are solved by a reformulation of the magnetic energy equation. The evolution of the pattern size at intermediate and very high fields can be understood by an analysis of limiting cases of the magnetization curve. In particular, at a very high field the pattern size reaches a constant saturation value which has been recently confirmed by experiments. The field for the onset of a nonlinear behavior is shifted to higher field strength due to a demagnetization effect. This can partially explain the ability of linear approaches to reproduce experimental data even at a high field. Finally, the impact of the nonlinearity of the magnetization curve on the transition between hexagonal and labyrinthine patterns is discussed.

Journal Article↗
PubMed2004

Empirical test for cellular automaton models of traffic flow.

Based on a detailed microscopic test scenario motivated by recent empirical studies of single-vehicle data, several cellular automaton models for traffic flow are compared. We find three levels of agreement with the empirical data: (1) models that do not reproduce even qualitatively the most important empirical observations, (2) models that are on a macroscopic level in reasonable agreement with the empirics, and (3) models that reproduce the empirical data on a microscopic level as well. Our results are not only relevant for applications, but also shed light on the relevant interactions in traffic flow.

Journal Article↗
PubMed2005

Square-lattice site percolation at increasing ranges of neighbor bonds.

We report site percolation thresholds for square lattice with neighbor bonds at various increasing ranges. Using Monte Carlo techniques we found that nearest neighbors (NN), next-nearest neighbors (NNN), next-next-nearest neighbors (4N), and fifth-nearest neighbors (6N) yield the same pc = 0.592... . The fourth-nearest neighbors (5N) give pc = 0.298... . This equality is proved to be mathematically exact using symmetry argument. We then consider combinations of various kinds of neighborhoods with (NN+NNN), (NN+4N), (NN+NNN+4N), and (NN+5N). The calculated associated thresholds are respectively pc = 0.407..., 0.337..., 0.288..., and 0.234... . The existing Galam-Mauger universal formula for percolation thresholds does not reproduce the data showing dimension and coordination number are not sufficient to build a universal law which extends to complex lattices.

Journal Article↗
PubMed2006

Phase behavior of mixtures of oppositely charged protein nanoparticles at asymmetric charge ratios.

We present experimental and theoretical results for the phase behavior of mixtures of oppositely charged globular protein molecules in aqueous solutions containing monovalent salt. These colloidal mixtures are interesting model systems, on the one hand for electrolyte solutions ("colloidal ionic liquids"), and on the other for mixtures of oppositely charged (bio)macromolecules, colloids, micelles, etc., with the range of the electrostatic interactions (Debye length) easily tunable from much smaller to much larger than the particle size, simply by adding different amounts of monovalent salt. In this paper we investigate the phase behavior of such mixtures in the case that equally sized colloids have a large difference in charge magnitude. This is possible at any mixing ratio because small ions compensate any colloidal charge asymmetry. Our experimental system is based on lysozyme, a positively charged "hard" globular protein molecule, and succinylated lysozyme, a chemical modification of lysozyme which is negatively charged. By changing the solution pH we can adjust the ratio of charge between the two molecules. To describe phase separation into a dilute phase and a dense "complex" phase, a thermodynamic model is set up in which we combine the Carnahan-Starling-van der Waals equation of state with a heterogeneous Poisson-Boltzmann cell model and include the possibility that protein molecules adjust their charge when they move from one phase to the other (charge regulation). The theory uses the nonelectrostatic attraction strength as the only adjustable parameter and reasonably well reproduces the data in that complexation is only possible at intermediate , not too asymmetric mixing ratios, and low enough ionic strength and temperature.

Journal Article↗
PubMed2000

Formation of supported membranes from vesicles.

Using a combination of the quartz crystal microbalance and surface plasmon resonance techniques, we have studied the spontaneous formation of supported lipid bilayers from small (approximately 25 nm) unilamellar vesicles. Together these experimental methods measure the amount of lipid adsorbed on the surface and the amount of water trapped by the lipid. With this approach, we have, for the first time, been able to observe in detail the progression from the adsorption of intact vesicles to rupture and bilayer formation. Monte Carlo simulations reproduce the data.

Adsorption↗
PubMed2002

Monitoring the transitions of the charge-induced reconstruction of Aau(110) by reflectance anisotropy spectroscopy.

Missing-row reconstructions on Au(110) immersed in electrolytes have been studied by in situ reflectance anisotropy spectroscopy. Transitions between the 1 x 3, 1 x 2, and 1 x 1 surface structures were monitored as a function of the applied potential. A kinetic model allowed us to reproduce the data satisfactorily. These results confirm the theoretical predictions showing that the surface charge determines the surface reconstruction. The transition potentials and the activation barriers were determined.

Journal Article↗
PubMed2003

Spin-density response function in a 2D electron system under a magnetic field.

We study the spin density response function in a two-dimensional electron system under a strong perpendicular magnetic field. The theoretical framework is the extended RPA which takes into account all the second order self-energies of particle-hole propagators. Our results reproduce the data obtained by a light scattering experiment. We clarify how the extended RPA explains the empirical findings which are different even qualitatively from the RPA response. Especially the important role played by the two-particle-two-hole degrees of freedom is stressed.

Journal Article↗
PubMed2005

Discrete and continuum spectra in the unified shell model approach.

A new version of the nuclear shell model unifies the consideration of the discrete spectrum, where the results reproduce the standard shell model, and continuum. The ingredients of the method are the non-Hermitian effective Hamiltonian, energy-dependent one-body and two-body decay amplitudes, and self-consistent treatment of thresholds. The results for helium and oxygen isotope chains reproduce the data well.

Journal Article↗
PubMed2005

Surprises in threshold antikaon-nucleon physics.

Low energy KN interactions are studied within unitary chiral perturbation theory at next-to-leading order with ten coupled channels. We pay special attention to the recent precise determination of the strong shift and width of the kaonic hydrogen 1s state by the DEAR Collaboration that has challenged our theoretical understanding of this sector of strong interactions. We typically find two classes of solutions, both of them reproducing previous data, that either can or cannot accommodate the DEAR measurements. The former class has not been previously discussed.

Journal Article↗