To what extent can dynamical models describe statistical features of turbulent flows?

Statistical features of "bursty" behaviour in charged and neutral fluid turbulence, are compared to statistics of intermittent events in a GOY shell model, and avalanches in different models of Self Organized Criticality (SOC). It is found that inter-burst times show a power law distribution for turbulent samples and for the shell model, a property which is shared only in a particular case of the running sandpile model. The breakdown of self-similarity generated by isolated events observed in the turbulent samples, is well reproduced by the shell model, while it is absent in all SOC models considered. On this base, we conclude that SOC models are not adequate to mimic fluid turbulence, while the GOY shell model constitutes a better candidate to describe the gross features of turbulence.Comment: 14 pages, 4 figures, in press on Europhys. Lett. (may 2002

Environmental Implications of a Stabilization Pond Effluent Released in Paraná River at Ilha Solteira, Brazil: The Quality of Water and Sediment

Sewage treatment plants in Ilha Solteira City, which consist of stabilization ponds, have been modifying water and sediment characteristics around sewage outfall area. Water quality parameters such as dissolved oxygen (OD) and conductivity were directly influenced by the sewage outfall. OD values were reported before (6.36 mg L-1) and after (2.94 mg L-1) the sewage outfall. Measurement of organic matter content in the sediment showed the same pattern, with values of 1.34% and 4.80% for the SP1 and SP3 samples, respectively. A copper and zinc analysis indicated that metals are being transported through the water column, and SP3 is an important sedimentation zone. The total concentrations reported for copper are 6.48, 26.97, 37.54, 27.12 and 18.55 mg kg-1 for SP1, SP2, SP3, SP4 and SP5, respectively, and the total concentrations for zinc are 11.21, 48.53, 67.41, 58.62 and 24.76 mg kg-1. Bureau Community of Reference (BCR) sequential extraction indicated the following bioavailability order of copper and zinc: SP1 < SP5 < SP4 < SP3 < SP2. At SP2, more than 70% of the copper and zinc is found in bioavailable fractions. Benthic organism’s analysis indicates that the Oligochaetes correlation with organic matter content is related to the decrease in water quality. DOI: http://dx.doi.org/10.17807/orbital.v7i4.77

Allogeneic mesenchymal stem cells improve the wound healing process of sheep skin

Abstract Background Skin wound healing includes a system of biological processes, collectively restoring the integrity of the skin after injury. Healing by second intention refers to repair of large and deep wounds where the tissue edges cannot be approximated and substantial scarring is often observed. The objective of this study was to evaluate the effects of mesenchymal stem cells (MSCs) in second intention healing using a surgical wound model in sheep. MSCs are known to contribute to the inflammatory, proliferative, and remodeling phases of the skin regeneration process in rodent models, but data are lacking for large animal models. This study used three different approaches (clinical, histopathological, and molecular analysis) to assess the putative action of allogeneic MSCs at 15 and 42 days after lesion creation. Results At 15 days post-lesion, the wounds treated with MSCs showed a higher degree of wound closure, a higher percentage of re-epithelialization, proliferation, neovascularization and increased contraction in comparison to a control group. At 42 days, the wounds treated with MSCs had more mature and denser cutaneous adnexa compared to the control group. The MSCs-treated group showed an absence of inflammation and expression of CD3+ and CD20+. Moreover, the mRNA expression of hair-keratine (hKER) was observed in the MSCs-treated group 15 days after wound creation and had increased significantly by 42 days post-wound creation. Collagen1 gene (Col1α1) expression was also greater in the MSCs-treated group compared to the control group at both days 15 and 42. Conclusion Peripheral blood-derived MSCs may improve the quality of wound healing both for superficial injuries and deep lesions. MSCs did not induce an inflammatory response and accelerated the appearance of granulation tissue, neovascularization, structural proteins, and skin adnexa

Theory for Dynamical Short Range Order and Fermi Surface Volume in Strongly Correlated Systems

Using the fluctuation exchange approximation of the one band Hubbard model, we discuss the origin of the changing Fermi surface volume in underdoped cuprate systems due to the transfer of occupied states from the Fermi surface to its shadow, resulting from the strong dynamical antiferromagnetic short range correlations. The momentum and temperature dependence of the quasi particle scattering rate shows unusual deviations from the conventional Fermi liquid like behavior. Their consequences for the changing Fermi surface volume are discussed. Here, we investigate in detail which scattering processes might be responsible for a violation of the Luttinger theorem. Finally, we discuss the formation of hole pockets near half filling.Comment: 5 pages, Revtex, 4 postscript figure

Results of a multi-country exploratory survey of approaches and methods for IMCI case management training

<p>Abstract</p> <p>Background</p> <p>The Integrated Management of Childhood Illness Strategy (IMCI) is effective in improving management of sick children, and thus child survival. It is currently recommended that in-service IMCI case management training (ICMT) occur over 11-days; that the participant: facilitator ratio should be ≤4:1 and that at least 30% of ICMT time be spent on clinical practice. In 2006–2007, approximately ten years after IMCI implementation, we conducted a multi-country exploratory questionnaire survey to document country experiences with ICMT, and to determine the acceptability of shortening duration of ICMT.</p> <p>Methods</p> <p>Questionnaires (QA) were sent to national IMCI focal persons in 27 purposively-selected countries. To probe further, questionnaires (QB and QC respectively) were also sent to course-directors or facilitators and IMCI trainees, selected using snowball sampling after applying pre-defined criteria, in these countries. Questionnaires gathered quantitative and qualitative data.</p> <p>Results</p> <p>Thirty-three QA, 163 QB, 272 QC and two summaries were returned from 24 countries. All countries continued to adapt course content to local disease burden. All countries offer shorter ICMT courses, ranging from 3–10 days (commonest being 5–8 days). The shorter ICMT courses offer fewer exercises, more homework, less individual feedback and reduced clinical practice (<30% time). Whereas changes to course content were usually evidence-based, changes to training methodology and course duration evolved as pressure to expand implementation mounted. Participants varied in their self-reported skill and perception about each course. However, the varied methodology and integrated approach to management of illnesses were commonly cited as strengths of ICMT, and the chart booklet and clinical practice sessions were identified as critical components of ICMT. Four themes emerged from the qualitative work, viz. the current 11-day course is too expensive and should be shortened; advocacy around IMCI should increase; content should be regularly updated, new content areas should be introduced cautiously and more attention should be paid to skills-building rather than knowledge accumulation.</p> <p>Conclusion</p> <p>Whilst the 11-day ICMT course is still recommended, as efforts intensify to increase access to quality care and meet MDG4, standardized shorter ICMT courses, that include participatory methodologies and adequate clinical practice, could be acceptable globally.</p

The plasma boundary in Single Helical Axis RFP plasmas

Single Helical Axis (SHAx) states obtained in high current reversed field pinch (RFP) plasmas display, aside from a dominant mode in the m=1 spectrum, also a dominant m=0 mode, with the same toroidal mode number as the m=1 one. The two modes have a fixed phase relationship. The island chain created by the m=0 mode across the reversal surface gives rise, at shallow reversal of the toroidal field, to an X-point structure which separates the last closed flux surface from the first wall, creating a divertor-like configuration. The plasma-wall interaction is found to be related to the connection length of the field lines intercepting the wall, which displays a pattern modulated by the dominant mode toroidal periodicity. This configuration, which occurs only for shallow toroidal field reversal, could be exploited to realize an island divertor in analogy to stellarators.Comment: 12 pages, 9 figures Submitted to Nuclear Fusio

Evaluation of fluoride release from experimental TiF4 and NaF varnishes in vitro

Fluoride varnishes play an important role in the prevention of dental caries, promoting the inhibition of demineralization and the increase of remineralization. OBJECTIVE: This study aimed to analyze the amount of fluoride released into water and artificial saliva from experimental TiF(4 )and NaF varnishes, with different concentrations, for 12 h. MATERIAL AND METHODS: Fluoride varnishes were applied on acrylic blocks and then immersed in 10 ml of deionized water and artificial saliva in polystyrene bottles. The acrylic blocks were divided in seven groups (n=10): 1.55% TiF(4 )varnish (0.95% F, pH 1.0); 3.10% TiF(4 )varnish (1.90% F, pH 1.0); 3.10% and 4% TiF(4 )varnish (2.45% F, pH 1.0); 2.10% NaF varnish (0.95% F, pH 5.0); 4.20% NaF varnish (1.90% F, pH 5.0); 5.42% NaF varnish (2.45% F, pH 5.0) and control (no treatment, n=5). The fluoride release was analyzed after 1/2, 1, 3, 6, 9 and 12 h of exposure. The analysis was performed using an ion-specific electrode coupled to a potentiometer. Two-way ANOVA and Bonferroni's test were applied for the statistical analysis (p<0.05). RESULTS: TiF(4 )varnishes released larger amounts of fluoride than NaF varnishes during the first 1/2 h, regardless of their concentration; 4% TiF(4) varnish released more fluoride than NaF varnishes for the first 6 h. The peak of fluoride release occurred at 3 h. There was a better dose-response relationship among the varnishes exposed to water than to artificial saliva. CONCLUSIONS: The 3.10% and 4% TiF(4 )-based varnishes have greater ability to release fluoride into water and artificial saliva compared to NaF varnish; however, more studies must be conducted to elucidate the mechanism of action of TiF(4 )varnish on tooth surface

Disinfection of Ocular Cells and Tissues by Atmospheric-Pressure Cold Plasma

Background: Low temperature plasmas have been proposed in medicine as agents for tissue disinfection and have received increasing attention due to the frequency of bacterial resistance to antibiotics. This study explored whether atmospheric-pressure cold plasma (APCP) generated by a new portable device that ionizes a flow of helium gas can inactivate ocular pathogens without causing significant tissue damage. Methodology and Principal Findings: We tested the APCP effects on cultured Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus fumigatus and Herpes simplex virus-1, ocular cells (conjunctival fibroblasts and keratocytes) and ex-vivo corneas. Exposure to APCP for 0.5 to 5 minutes significantly reduced microbial viability (colony-forming units) but not human cell viability (MTT assay, FACS and Tunel analysis) or the number of HSV-1 plaque-forming units. Increased levels of intracellular reactive oxygen species (ROS) in exposed microorganisms and cells were found using a FACS-activated 2',7'-dichlorofluorescein diacetate probe. Immunoassays demonstrated no induction of thymine dimers in cell cultures and corneal tissues. A transient increased expression of 8-OHdG, genes and proteins related to oxidative stress (OGG1, GPX, NFE2L2) was determined in ocular cells and corneas by HPLC, qRT-PCR and Western blot analysis. Conclusions: A short application of APCP appears to be an efficient and rapid ocular disinfectant for bacteria and fungi without significant damage on ocular cells and tissues, although the treatment of conjunctival fibroblasts and keratocytes caused a time-restricted generation of intracellular ROS and oxidative stress-related responses

Relationship between Audiometric Slope and Tinnitus Pitch in Tinnitus Patients: Insights into the Mechanisms of Tinnitus Generation

BACKGROUND: Different mechanisms have been proposed to be involved in tinnitus generation, among them reduced lateral inhibition and homeostatic plasticity. On a perceptual level these different mechanisms should be reflected by the relationship between the individual audiometric slope and the perceived tinnitus pitch. Whereas some studies found the tinnitus pitch corresponding to the maximum hearing loss, others stressed the relevance of the edge frequency. This study investigates the relationship between tinnitus pitch and audiometric slope in a large sample. METHODOLOGY: This retrospective observational study analyzed 286 patients. The matched tinnitus pitch was compared to the frequency of maximum hearing loss and the edge of the audiogram (steepest hearing loss) by t-tests and correlation coefficients. These analyses were performed for the whole group and for sub-groups (uni- vs. bilateral (117 vs. 338 ears), pure-tone vs. narrow-band (340 vs. 115 ears), and low and high audiometric slope (114 vs. 113 ears)). FINDINGS: For the right ear, tinnitus pitch was in the same range and correlated significantly with the frequency of maximum hearing loss, but differed from and did not correlate with the edge frequency. For the left ear, similar results were found but the correlation between tinnitus pitch and maximum hearing loss did not reach significance. Sub-group analyses (bi- and unilateral, tinnitus character, slope steepness) revealed identical results except for the sub-group with high audiometric slope which revealed a higher frequency of maximum hearing loss as compared to the tinnitus pitch. CONCLUSION: The study-results confirm a relationship between tinnitus pitch and maximum hearing loss but not to the edge frequency, suggesting that tinnitus is rather a fill-in-phenomenon resulting from homeostatic mechanisms, than the result of deficient lateral inhibition. Sub-group analyses suggest that audiometric steepness and the side of affected ear affect this relationship. Future studies should control for these potential confounding factors

Environmental Implications of a Stabilization Pond Effluent Released in Paraná River at Ilha Solteira, Brazil: The Quality of Water and Sediment

Sewage treatment plants in Ilha Solteira City, which consist of stabilization ponds, have been modifying water and sediment characteristics around sewage outfall area. Water quality parameters such as dissolved oxygen (OD) and conductivity were directly influenced by the sewage outfall. OD values were reported before (6.36 mg L-1) and after (2.94 mg L-1) the sewage outfall. Measurement of organic matter content in the sediment showed the same pattern, with values of 1.34% and 4.80% for the SP1 and SP3 samples, respectively. A copper and zinc analysis indicated that metals are being transported through the water column, and SP3 is an important sedimentation zone. The total concentrations reported for copper are 6.48, 26.97, 37.54, 27.12 and 18.55 mg kg-1 for SP1, SP2, SP3, SP4 and SP5, respectively, and the total concentrations for zinc are 11.21, 48.53, 67.41, 58.62 and 24.76 mg kg-1. Bureau Community of Reference (BCR) sequential extraction indicated the following bioavailability order of copper and zinc: SP1 < SP5 < SP4 < SP3 < SP2. At SP2, more than 70% of the copper and zinc is found in bioavailable fractions. Benthic organism’s analysis indicates that the Oligochaetes correlation with organic matter content is related to the decrease in water quality. DOI: http://dx.doi.org/10.17807/orbital.v7i4.77