CRITICAL POINTS OF THE PRODUCTION PROCESS OF SOLID WOOD FLOORING

The quality concepts represent one of the important factors for the success of organizations and among these concepts the stabilization of the production process contributes to the improvement, waste reduction and increased competitiveness. Thus, this study aimed to evaluate the production process of solid wood flooring on its predictability and capacity, based on its critical points. Therefore, the research was divided into three stages. The first one was the process mapping of the company and the elaboration of flowcharts for the activities. The second one was the identification and the evaluation of the critical points using FMEA (Failure Mode and Effect Analysis) adapted methodology. The third one was the evaluation of the critical points applying the statistical process control and the determination of the process capability for the C-pk index. The results showed the existence of six processes, two of them are critical. In those two ones, fifteen points were considered critical and two of them, related with the dimension of the pieces and defects caused by sandpaper, were selected for evaluation. The productive process of the company is unstable and not capable to produce wood flooring according to the specifications and, therefore these specifications should be reevaluated.

Effects of bovine sperm cryopreservation using different freezing techniques and cryoprotective agents on plasma, acrosomal and mitochondrial membranes

The success of semen cryopreservation is influenced by several factors, such as freezing curves and cryoprotectants. These two factors are of special interest once they may lead to many important physical-chemical changes resulting in different degrees of damage in spermatozoa structure. This experiment was designed to compare the effect of bull semen cryopreservation using two freezing techniques: conventional (CT cooling rate of -0.55 degrees C min-1 and freezing rate of -19.1 degrees C min-1) and automated (AT cooling rate of -0.23 degrees C min-1 and freezing rate of -15 degrees C min-1), performed with different curves, and with three cryoprotectants (glycerol, ethylene glycol and dimethyl formamide) on bovine sperm motility and integrity of plasma, acrosomal and mitochondrial membranes. These variables were simultaneously evaluated using the fluorescence probes propidium iodide, fluorescein-conjugated Pisum sativum agglutinin and MitoTracker Green FM. The effects of freezing techniques, as well as of different cryoprotectants were analysed by the analysis of variance. The means were compared by Fishers test. There were no significant differences between freezing techniques (P > 0.05). Glycerol showed higher percentages of motility, vigour and integrity of plasma, acrosomal and mitochondrial membranes than other two cryoprotectants (P < 0.05). Ethylene glycol preserved higher motility and integrity of plasma and mitochondrial membranes than dimethyl formamide (P < 0.05). Sperm motility with glycerol was 30.67 +/- 1.41% and 30.50 +/- 1.06%, with ethylene glycol was 21.17 +/- 1.66% and 21.67 +/- 1.13% and with dimethyl formamide was 8.33 +/- 0.65% and 9.17 +/- 0.72% to CT and AT curves, respectively. The percentage of spermatozoa with simultaneously intact plasma membrane, intact acrosome and mitochondrial function (IPIAH) was 14.82 +/- 1.49% (CT) and 15.83 +/- 1.26% (AT) to glycerol, 9.20 +/- 1.31% (CT) and 9.92 +/- 1.29% (AT) to ethylene glycol 4.65 +/- 0.93% (CT) and 5.17 +/- 0.87% (AT) to dimethyl formamide. Glycerol provided the best results, although nearly 85% of spermatozoa showed some degree of injury in their membranes, suggesting that further studies are required to improve the results of cryopreservation of bovine semen.

CTAB, Triton X-100 and freezing-thawing treatments of Candida guilliermondii: Effects on permeability and accessibility of the glucose-6-phosphate dehydrogenase, xylose reductase and xylitol dehydrogenase enzymes

Cells of Candida guilliermondii (ATCC 201935) were permeabilised with surfactant treatment (CTAB or Triton X-100) or a freezing-thawing procedure. Treatments were monitored by in situ activities of the key enzymes involved in xylose metabolism, that is, glucose-6-phosphate dehydrogenase (G6PD), xylose reductase (XR) and xylitol dehydrogenase (XD). The permeabilising ability of the surfactants was dependent on its concentration and incubation time. The optimum operation conditions for the permeabilisation of C. guilliermondii with surfactants were 0.41 mM (CTAB) or 2.78 mM (Triton X-100), 30 degrees C, and pH 7 at 200 rpm for 50 min. The maximum permeabilisation measured in terms of the in situ G6PD activity observed was, in order, as follows: CTAB (122.4 +/- 15.7 U/g(cells)) > freezing-thawing, , (54.3 +/- 1.9 U/g(cells)) > Triton X-100 (23.5 +/- 0.0 U/g(cells)). These results suggest that CTAB surfactant is more effective in the permeabilisation of C. guilliermondii cells in comparison to the freezing-thawing and Triton X-100 treatments. Nevertheless, freezing-thawing was the only treatment that allowed measurable in situ XR activity. Therefore, freezing-thawing permeabilised yeast cells could be used as a source of xylose reductase for analytical purposes or for use in biotransformation process such as xylitol preparation from xylose. The level of in situ xylose reductase was found to be 13.2 +/- 0.1 U/g(cells).

A simple method to evaluate, correlate and predict boiling and flash points of alkynes

Boiling points (T B) of acyclic alkynes are predicted from their boiling point numbers (Y BP) with the relationship T B(K) = -16.802Y BP2/3 + 337.377Y BP1/3 - 437.883. In turn, Y BP values are calculated from structure using the equation Y BP = 1.726 + Ai + 2.779C + 1.716M3 + 1.564M + 4.204E3 + 3.905E + 5.007P - 0.329D + 0.241G + 0.479V + 0.967T + 0.574S. Here Ai depends on the substitution pattern of the alkyne and the remainder of the equation is the same as that reported earlier for alkanes. For a data set consisting of 76 acyclic alkynes, the correlation of predicted and literature T B values had an average absolute deviation of 1.46 K, and the R² of the correlation was 0.999. In addition, the calculated Y BP values can be used to predict the flash points of alkynes.

Stability boundary characterization of nonlinear autonomous dynamical systems in the presence of saddle-node equilibrium points

A dynamical characterization of the stability boundary for a fairly large class of nonlinear autonomous dynamical systems is developed in this paper. This characterization generalizes the existing results by allowing the existence of saddle-node equilibrium points on the stability boundary. The stability boundary of an asymptotically stable equilibrium point is shown to consist of the stable manifolds of the hyperbolic equilibrium points on the stability boundary and the stable, stable center and center manifolds of the saddle-node equilibrium points on the stability boundary.

Regularizing a set of unstructured 3D points from a sequence of stereo images

[EN] In this paper we present a method for the regularization of a set of unstructured 3D points obtained from a sequence of stereo images. This method takes into account the information supplied by the disparity maps computed between pairs of images to constraint the regularization of the set of 3D points. We propose a model based on an energy which is composed of two terms: an attachment term that minimizes the distance from 3D points to the projective lines of camera points, and a second term that allows for the regularization of the set of 3D points by preserving discontinuities presented on the disparity maps. We embed this energy in a 2D finite element method. After minimizing, this method results in a large system of equations that can be optimized for fast computations. We derive an efficient implicit numerical scheme which reduces the number of calculations and memory allocations.

Experimentation and thermodynamic representations of binaries containing compounds of low boiling points: pentane and alkyl methanoates

[EN]This work presents experimental mixing properties, hEand vE, at several temperatures and the iso-baric vapor–liquid equilibria (iso-p VLE) at 101.32 kPa for four binaries containing pentane and four alkyl(methyl to butyl) methanoates. Particular conditions are established to work with these solutions withhighly volatile compounds, especially for the case of methyl methanoate + pentane system, for whicha continuous feeding device is designed and constructed for measuring the densities.

The Poincaré polynomial for the Hilbert scheme of points of C^2

Questo lavoro prende in esame lo schema di Hilbert di punti di C^2, il quale viene descritto assieme ad alcune sue proprietà, ad esempio la sua struttura hyper-kahleriana. Lo scopo della tesi è lo studio del polinomio di Poincaré di tale schema di Hilbert: ciò che si ottiene è una espressione del tipo serie di potenze, la quale è un caso particolare di una formula molto più generale, nota con il nome di formula di Goettsche.

Lamellar body ultrastructure revisited: high-pressure freezing and cryo-electron microscopy of vitreous sections

Lamellar bodies are the storage sites for lung surfactant within type II alveolar epithelial cells. The structure-function models of lamellar bodies are based on microscopic analyses of chemically fixed tissue. Despite available alternative fixation methods that are less prone to artifacts, such as cryofixation by high-pressure freezing, the nature of the lung, being mostly air filled, makes it difficult to take advantage of these improved methods. In this paper, we propose a new approach and show for the first time the ultrastructure of intracellular lamellar bodies based on cryo-electron microscopy of vitreous sections in the range of nanometer resolution. Thus, unspoiled by chemical fixation, dehydration and contrasting agents, a close to native structure is revealed. Our approach uses perfluorocarbon to substitute the air in the alveoli. Lung tissue was subsequently high-pressure frozen, cryosectioned and observed in a cryo-electron microscope. The lamellar bodies clearly show a tight lamellar morphology. The periodicity of these lamellae was 7.3 nm. Lamellar bifurcations were observed in our cryosections. The technical approach described in this paper allows the examination of the native cellular ultrastructure of the surfactant system under near in vivo conditions, and therefore opens up prospectives for scrutinizing various theories of lamellar body biogenesis, exocytosis and recycling.

Time-referenced effects of an internal vs. external focus of attention on muscular activity and compensatory variability

The paralysis-by-analysis phenomenon, i.e., attending to the execution of one's movement impairs performance, has gathered a lot of attention over recent years (see Wulf, 2007, for a review). Explanations of this phenomenon, e.g., the hypotheses of constrained action (Wulf et al., 2001) or of step-by-step execution (Masters, 1992; Beilock et al., 2002), however, do not refer to the level of underlying mechanisms on the level of sensorimotor control. For this purpose, a “nodal-point hypothesis” is presented here with the core assumption that skilled motor behavior is internally based on sensorimotor chains of nodal points, that attending to intermediate nodal points leads to a muscular re-freezing of the motor system at exactly and exclusively these points in time, and that this re-freezing is accompanied by the disruption of compensatory processes, resulting in an overall decrease of motor performance. Two experiments, on lever sequencing and basketball free throws, respectively, are reported that successfully tested these time-referenced predictions, i.e., showing that muscular activity is selectively increased and compensatory variability selectively decreased at movement-related nodal points if these points are in the focus of attention.

Evaluation of articular cartilage in patients with femoroacetabular impingement (FAI) using T2* mapping at different time points at 3.0 Tesla MRI: a feasibility study

To define the feasibility of utilizing T2* mapping for assessment of early cartilage degeneration prior to surgery in patients with symptomatic femoroacetabular impingement (FAI), we compared cartilage of the hip joint in patients with FAI and healthy volunteers using T2* mapping at 3.0 Tesla over time.

Dorsal rather than ventral visual pathways discriminate freezing status in Parkinson's disease

BACKGROUND: Although visuospatial deficits have been linked with freezing of gait (FOG) in Parkinson's disease (PD), the specific effects of dorsal and ventral visual pathway dysfunction on FOG is not well understood. METHOD: We assessed visuospatial function in FOG using an angle discrimination test (dorsal visual pathway bias) and overlapping figure test (ventral visual pathway bias), and recorded overall response time, mean fixation duration and dwell time. Covariate analysis was conducted controlling for disease duration, motor severity, contrast sensitivity and attention with Bonferroni adjustments for multiple comparisons. RESULTS: Twenty seven people with FOG, 27 people without FOG and 24 controls were assessed. Average fixation duration during angle discrimination distinguished freezing status: [F (1, 43) = 4.77 p < 0.05] (1-way ANCOVA). CONCLUSION: Results indicate a preferential dysfunction of dorsal occipito-parietal pathways in FOG, independent of disease severity, attentional deficit, and contrast sensitivity.