963 resultados para Subpixel precision
Resumo:
MOTOR IMPAIRMENTS ARE COMMON AFTER STROKE but efficacious therapies for these dysfunctions are scarce. Extending an earlier study on the effects of music-supported training (MST), behavioral indices of motor function were obtained before and after a series of training sessions to assess whether this new treatment leads to improved motor functions. Furthermore, music-supported training was contrasted to functional motor training according to the principles of constraint-induced therapy (CIT). In addition to conventional physiotherapy, 32 stroke patients with moderately impaired motor function and no previous musical experience received 15 sessions of MST over a period of three weeks, using a manualized, step-bystep approach. A control group consisting of 15 patients received 15 sessions of CIT in addition to conventional physiotherapy. A third group of 30 patients received exclusively conventional physiotherapy and served as a control group for the other three groups. Fine as well as gross motor skills were trained by using either a MIDI-piano or electronic drum pads programmed to emit piano tones. Motor functions were assessed by an extensive test battery. MST yielded significant improvement in fine as well as gross motor skills with respect to speed, precision, and smoothness of movements. These improvements were greater than after CIT or conventional physiotherapy. In conclusion, with equal treatment intensity, MST leads to more pronounced improvements of motor functions after stroke than CIT.
Resumo:
The use of an internal standard (IS) in ET AAS can be considered a new trend after the commercial introduction of a simultaneous spectrometer. The evaluation of experimental data to choose the most appropriate IS can be done by comparing correlation graphs. They were used to verify the resemblance among the simultaneous measurements obtained for the analyte(s) and the IS by inductively coupled plasma optical emission spectrometry (ICPOES). The judicious selection of IS by using correlation graphs for determinations by ET AAS can be exploited to improve the precision and accuracy of the analytical results. Therefore, a new approach for studying the use of IS in ET AAS is presented.
Resumo:
A new solid phase microextraction (SPME) system, known as in-tube SPME, was recently developed using an open tubular fused-silica capilary column, instead of an SPME fiber, as the SPME device. On-line in-tube SPME is usually used in combination with high performance liquid chromatography. Drugs in biological samples are directly extracted and concentrated in the stationary phase of capillary columns by repeated draw/eject cycles of sample solution, and then directly transferred to the liquid chromatographic column. In-tube SPME is suitable for automation. Automated sample handling procedures not only shorten the total analysis time, but also usually provide better accuracy and precision relative to manual techniques. In-tube SPME has been demonstrated to be a very effective and highly sensitive technique to determine drugs in biological samples for various purposes such as therapeutic drug monitoring, clinical toxicology, bioavailability and pharmacokinetics.
Resumo:
A boron-doped diamond electrode is used for determination of Mn(II) in atmospheric particulate matter by square wave cathodic stripping voltammetry. The analytical curve was linear for Mn(II) concentrations between 5.0 and 37.5 µg L-1, with quantification limit of 3.6 µg L-1. The precision was evaluated by the relative standard deviation, with values between 5.1% and 9.3%. The electrode is free of adsorption, minimizing memory effects. Samples collected in the workplace atmosphere of a foundry had Mn(II) concentrations between 0.4 and 4 µg m-3. No significant differences were observed between the proposed method and inductively coupled plasma optical emission spectroscopy.
Resumo:
Current technology trends in medical device industry calls for fabrication of massive arrays of microfeatures such as microchannels on to nonsilicon material substrates with high accuracy, superior precision, and high throughput. Microchannels are typical features used in medical devices for medication dosing into the human body, analyzing DNA arrays or cell cultures. In this study, the capabilities of machining systems for micro-end milling have been evaluated by conducting experiments, regression modeling, and response surface methodology. In machining experiments by using micromilling, arrays of microchannels are fabricated on aluminium and titanium plates, and the feature size and accuracy (width and depth) and surface roughness are measured. Multicriteria decision making for material and process parameters selection for desired accuracy is investigated by using particle swarm optimization (PSO) method, which is an evolutionary computation method inspired by genetic algorithms (GA). Appropriate regression models are utilized within the PSO and optimum selection of micromilling parameters; microchannel feature accuracy and surface roughness are performed. An analysis for optimal micromachining parameters in decision variable space is also conducted. This study demonstrates the advantages of evolutionary computing algorithms in micromilling decision making and process optimization investigations and can be expanded to other applications
Resumo:
Several extraction procedures are described for the determination of exchangeable and fixed ammonium, nitrate + nitrite, total exchangeable nitrogen and total nitrogen in certified reference soils and petroleum reservoir rock samples by steam distillation and indophenol method. After improvement of the original distillation system, an increase in worker safety, a reduction in time consumption, a decrease of 73% in blank value and an analysis without ammonia loss, which could possibly occur, were achieved. The precision (RSD < 8%, n = 3) and the detection limit (9 mg kg-1 NH4+-N) are better than those of published procedures.
Resumo:
An analytical study based on extraction with acetonitrile-water, immunoaffinity column cleanup, and HPLC/fluorescence detection for separation and identification of ochratoxin A in coriander was carried out. Validation of the applied methodology was done through accuracy and precision studies. Homogenized samples of coriander were spiked in triplicate with ochratoxin A at 0.5, 1.0, 2.0, and 5.0 µg/kg levels. Recovery values were in the range of 98% for a fortification level at 0.5 µg/kg to 109.1% at 1.0 µg/kg. Application to coriander samples available in Portuguese markes showed no contamination with ochratoxin A.
Resumo:
Tämän diplomityön tarkoituksena oli tutkia tarkkuuselektroniikkatuotteen ympäristönäkökohtia elinkaariarvioinnin avulla. Työn osana tehtiin elinkaariarviointi (LCA) kahdelle tarkkuuselektroniikkatuotteelle. LCA:ssa keskityttiin elinkaaren kehdosta-asiakkaalle-vaiheisiin. Työn tavoitteena oli tuottaa määrällistä ja laadullista tietoa valittujen tuotteiden ympäristövaikutuksista. Selvitys tehtiin yrityksen tuotesuunnittelun tueksi. LCA:n inventaarioanalyysiin kerättiin prosessikohtaista tietoa selvityksen aikana. Myös kaupallista LCA-ohjelmaa ja sen tarjoamia tietopankkeja hyödynnettiin elinkaariarvioinnin toteuttamisessa. Teoriaosassa esitellään LCA-menetelmä. Lisäksi tarkastellaan elinkaariarviointiin liittyviä tuotekohtaisia ympäristökysymyksiä. Työssä eritellään myös yleisesti tarkkuuselektroniikkatuotteen eri osien elinkaareen vaiheita ja niihin liittyviä ympäristönäkökohtia. Kokeellisessa osassa kuvataan kahdelle tuotteelle tehtyä LCA-tapaustutkimusta. Elinkaariarvioinnin inventaariotiedon lähteet kuvataan. Inventaarioanalyysin ja vaikutusarvioinnin avulla tuodaan esille tuotteiden ympäristökuormaan merkittävimmin vaikuttavat prosessit ja elinkaaren vaiheet. Lisäksi tarkastellaan miten tapaustuotteiden ympäristökuormaa voitaisiin pienentää kahden esimerkin avulla. Lopuksi annetaan suosituksia jatkotoimenpiteistä tuotesuunnitteluun ja tiedonkeruuseen.
Resumo:
A high performance liquid chromatography method was developed to quantify lamivudine, stavudine and nevirapine combined in tablets. The separation was carried out in less than 10 min using a phosphate buffer of pH 3.0 and acetonitrile (75:25, v/v) as mobile phase, a LiChrospher ODS column and UV detection at 266 nm. The method was linear over the range of 15-135 µg/mL (lamivudine), 4-36 µg/mL (stavudine) and 20-180 µg/mL (nevirapine). The accuracy ranged from 98.56 to 102.04% and intra-day and inter-day precision was less than 1% for the three drugs. The method showed robustness, remaining unaffected by deliberate variations in relevant parameters.
Resumo:
A simple and reliable ashing procedure is proposed for the preparation of used lubricating oil samples for the determination of Zn, Fe, Pb, Ni and Cu by the flame atomic absorption spectrometry technique. Sulphanilic acid was added to oil samples, the mixture coked and the coke ashed at 550 ºC. The solutions of the ash were analysed by flame AAS for these metals. The quantification limits were 38.250 µg g-1 for Zn, 4.550 µg g-1 for Fe, 1.562 µg g-1 for Pb, 1.450 µg g-1 for Ni, and 0.439 µg g-1 for Cu. The determinations, in lubricating oil, showed good precision and accuracy with recoveries between 90 and 110 %, indicating a negligible matrix effect in the experiments using addition of analyte, with relative standard deviation lower than 5%. The results for analysis of wastewater contamined by theses lubricants showed a very high relative standard deviation.
Resumo:
A rapid and efficient method for the analysis of histamine in wines using HPLC with fluorescence detection after derivatization was developed and validated. The method LOD and LOQ values were 0.25 and 0.50 mg L-1 respectively. The repeatability and intermediary precision for the instrument and for the method presented RSD values of 3.7 and 2.9%, and 6.0 and 5.6%, respectively. The recoveries were 95.5 and 89.9% for the fortification levels of 2 and 10 mg L-1. The method was applied to determine the histamine content in Cabernet Sauvignon wines, which presented values between 1.2 and 5.7 mg L-1.
Resumo:
A proficiency assay of the determination of dithiocarbamate pesticide residues in banana was carried out. Fourteen laboratories participated in this study. Homogeneity and stability testing were performed by INCQS on the samples sent to the laboratories. Analytical results supplied by the pesticide residues laboratory of the VWA/KvW, Amsterdam, Holland, were used to define the designated value for the thiram concentration in the study samples. RESULTS: Fifty percent of the participating laboratories had satisfactory results. Efforts are needed to improve the precision of the analytical results and to decrease the number of false negative results observed.
Resumo:
A simple method was proposed for determination of paracetamol and ibuprofen in tablets, based on UV measurements and partial least squares. The procedure was performed at pH 10.5, in the concentration ranges 3.00-15.00 µg ml-1 (paracetamol) and 2.40-12.00 µg ml-1 (ibuprofen). The model was able to predict paracetamol and ibuprofen in synthetic mixtures with root mean squares errors of prediction of 0.12 and 0.17 µg ml-1, respectively. Figures of merit (sensitivity, limit of detection and precision) were also estimated. The results achieved for the determination of these drugs in pharmaceutical formulations were in agreement with label claims and verified by HPLC.
Resumo:
The liquid-liquid extraction with the low temperature partition technique was developed for the analysis of four pyrethroids in water by CG. Using a factorial design the extraction technique was optimised evaluating the effect of the variables ionic strength, contact time and proportion between sample and solvent volumes. The validation parameters sensitivity, precision, accuracy and detection and quantification limits were evaluated. The LOD and LOQ of the method varied from 1.1 to 3.2 µg L-1 and 2.7 to 9.5 µg L-1, respectively.
Resumo:
Large differences in reduced glutathione (GSH) levels have been found in different investigations, also in healthy people. GSH oxidation in vitro has been associated with sample acidification in the presence of oxihemoglobin. In this work, the influence of different acids on GSH determination utilizing HPLC with UV detection was evaluated. The results showed that metaphosphoric acid and sulfosalicylic acid were inadequate for analysis, because metaphosphoric acid showed to be inefficient for deproteinization and with sulfosalicylic acid loss of GSH was observed. Trichloroacetic acid did not effect GSH quantification, since the deproteinized form was immediately derivatized with 5, 5´-dithio-bis (2-nitrobenzoic) acid. Methods with TCA deproteinization presented linear results from 0.5 to 3.0 mM. The correlation coefficient between aqueous curves and GSH spiked RBC exceeded 0.99. Precision calculations showed CV lower than 10% and bias within ± 10% for concentrations of 0.5; 1.5 and 3.0 mM GSH. The recovery was higher than 94%. Moreover, GSH blood concentrations were independent of hemoglobin concentrations.