11 resultados para Frequency upconversion process
em BORIS: Bern Open Repository and Information System - Berna - Suiça
Resumo:
Tissue engineering has been increasingly brought to the scientific spotlight in response to the tremendous demand for regeneration, restoration or substitution of skeletal or cardiac muscle after traumatic injury, tumour ablation or myocardial infarction. In vitro generation of a highly organized and contractile muscle tissue, however, crucially depends on an appropriate design of the cell culture substrate. The present work evaluated the impact of substrate properties, in particular morphology, chemical surface composition and mechanical properties, on muscle cell fate. To this end, aligned and randomly oriented micron (3.3±0.8 μm) or nano (237±98 nm) scaled fibrous poly(ε-caprolactone) non-wovens were processed by electrospinning. A nanometer-thick oxygen functional hydrocarbon coating was deposited by a radio frequency plasma process. C2C12 muscle cells were grown on pure and as-functionalized substrates and analysed for viability, proliferation, spatial orientation, differentiation and contractility. Cell orientation has been shown to depend strongly on substrate architecture, being most pronounced on micron-scaled parallel-oriented fibres. Oxygen functional hydrocarbons, representing stable, non-immunogenic surface groups, were identified as strong triggers for myotube differentiation. Accordingly, the highest myotube density (28±15% of total substrate area), sarcomeric striation and contractility were found on plasma-coated substrates. The current study highlights the manifold material characteristics to be addressed during the substrate design process and provides insight into processes to improve bio-interfaces.
Resumo:
Site-selective spectroscopy in hexagonal beta-NaYF4:Er3+,Yb3+ has revealed different environments for Er3+ ions (multisite formation). The low-temperature S-4(3/2) -> (I15/2Er3+)-I-4 green emission depends on the excitation wavelength associated with the F-4(7/2) Er3+ level. We have studied the effect of hydrostatic pressure on the green, red, and blue Er3+ emission upon NIR excitation at similar to 980 nm, in order to establish the role played by energy resonance conditions and the multiple Er3+ sites due to the disordered structure for the upconversion (UC) process (energy tuning). The variation of photoluminescence spectra and lifetimes as a function of pressure and temperature reveals that the origin of the high green UC efficiency of the beta-NaYF4:Er3+,Yb3+ compound is mainly due to the multisite distribution, and the low phonon energy of the host lattice.
Resumo:
AIMS: The objective of the present study was to investigate the relationship between extremely low-frequency magnetic field (ELF-MF) exposure and mortality from several neurodegenerative conditions in Swiss railway employees. METHODS: We studied a cohort of 20,141 Swiss railway employees with 464,129 person-years of follow-up between 1972 and 2002. For each individual, cumulative exposure was calculated from on-site measurements and modelling of past exposure. We compared cause-specific mortality in highly exposed train drivers (mean exposure: 21 microT) with less exposed occupational groups (for example station masters: 1 microT). RESULTS: The hazard ratio for train drivers compared to station masters was 1.96 [95% confidence interval (CI) = 0.98-3.92] for senile dementia and 3.15 (95% CI = 0.90-11.04) for Alzheimer's disease. For every 10 microT years of cumulative exposure senile dementia mortality increased by 5.7% (95% CI = 1.3-10.4), Alzheimer's disease by 9.4% (95% CI = 2.7-16.4) and amyotrophic lateral sclerosis by 2.1% (95% CI = -6.8 to 11.7). There was no evidence for an increase in mortality from Parkinson's disease and multiple sclerosis. CONCLUSIONS: This study suggests a link between exposure to ELF-MF and Alzheimer's disease and indicates that ELF-MF might act in later stages of the disease process.
Resumo:
Childhood extraordinary daytime urinary frequency is likely a common but underreported condition characterized by daytime frequent voiding and typically not linked with complaints of burning, urinary incontinence, altered urinary stream, changes in the nighttime voiding pattern, excessive fluid intake and excessive urinary volume. To determine the features and outcome of extraordinary daytime urinary frequency, we report our experience with 14 children and the results of a formal systematic analysis of peer-reviewed English-language literature on this topic. Nineteen case series were found (together with 16 mostly pertinent comments), with each case series providing details on from one to 119 children. On the basis of our experience and the findings of our systematic analysis, we conclude that, in general practice, extraordinary daytime urinary frequency is a common cause of urinary frequency, that the age of such patients is, on average, 6 years and that the micturation abnormalities persist for an average of 6 months. The results of this review must be viewed with an understanding of the limitations of the analysis process, which incorporated data exclusively from case series.
Resumo:
Upconversion (UC) is a promising option to enhance the efficiency of solar cells by conversion of sub-bandgap infrared photons to higher energy photons that can be utilized by the solar cell. The UC quantum yield is a key parameter for a successful application. Here the UC luminescence properties of Er3+-doped Gd2O2S are investigated by means of luminescence spectroscopy, quantum yield measurements, and excited state dynamics experiments. Excitation into the maximum of the 4I15/2 → 4I13/2 Er3+ absorption band around 1500 nm induces very efficient UC emission from different Er3+ excited states with energies above the silicon bandgap, in particular, the emission originating from the 4I11/2 state around 1000 nm. Concentration dependent studies reveal that the highest UC quantum yield is realized for a 10% Er3+-doping concentration. The UC luminescence is compared to the well-known Er3+-doped β-NaYF4 UC material for which the highest UC quantum yield has been reported for 25% Er3+. The UC internal quantum yields were measured in this work for Gd2O2S: 10%Er3+ and β-NaYF4: 25%Er3+ to be 12 ± 1% and 8.9 ± 0.7%, respectively, under monochromatic excitation around 1500 nm at a power of 700 W/m2. The UC quantum yield reported here for Gd2O2S: 10%Er3+ is the highest value achieved so far under monochromatic excitation into the 4I13/2 Er3+ level. Power dependence and lifetime measurements were performed to understand the mechanisms responsible for the efficient UC luminescence. We show that the main process yielding 4I11/2 UC emission is energy transfer UC.
Resumo:
In natural hazard research, risk is defined as a function of (1) the probability of occurrence of a hazardous process, and (2) the assessment of the related extent of damage, defined by the value of elements at risk exposed and their physical vulnerability. Until now, various works have been undertaken to determine vulnerability values for objects exposed to geomorphic hazards such as mountain torrents. Yet, many studies only provide rough estimates for vulnerability values based on proxies for process intensities. However, the deduced vulnerability functions proposed in the literature show a wide range, in particular with respect to medium and high process magnitudes. In our study, we compare vulnerability functions for torrent processes derived from studies in test sites located in the Austrian Alps and in Taiwan. Based on this comparison we expose needs for future research in order to enhance mountain hazard risk management with a particular focus on the question of vulnerability on a catchment scale.
Resumo:
It is well established that the therapeutic relationship contributes about as much to therapy outcome as 'technical' intervention. Furthermore, it follows clear prescriptive concepts in the same manner as technical interventions do. 'Motive Oriented Therapeutic Relationship' is such a concept for establishing a solid basis for whatever therapeutic work the patients' problems require (Grawe, 1980, 1992; Caspar, 1996). Yet, the therapeutic relationship doesn't explain everything because other factors play a significant role too. Previous studies showed that outcome is clearly better when therapists achieved a generally high quality of a therapeutic relationship when they did not shy away from possibly threatening interventions such as confrontations. This ratio of a fruitful alliance and marginally present confrontations in the same session also showed significant correlations with patient's assessment of alliance and progress in therapy (Figlioli et al., 2009).Aim: The current state of research in the field does not give any answers to questions like how good and bad confrontations can be characterized or what role does the intensity, respectively frequency of confrontations play in the process of psychotherapy. Methods: A sample of 80 therapies of 3 sessions each representing either good or bad outcome was judged moment by moment by independent raters if and how therapists used confrontative interventions. Results: Preliminary analyses show that successful confrontations are explicitly uttered, short but intense, related to important patients goals in therapy and embedded in prior complementarity. Discussion: The results will be discussed in terms of their implications for the clinical daily work.
Resumo:
It is well established that the therapeutic relationship contributes about as much to therapy outcome as ‘technical’ intervention. Furthermore, it follows clear prescriptive concepts in the same manner as technical interventions do. ‘Motive Oriented Therapeutic Relationship’ is such a concept for establishing a solid basis for whatever therapeutic work the patients’ problems require (Grawe, 1980, 1992; Caspar, 1996). Yet, the therapeutic relationship doesn’t explain everything because other factors play a significant role too. Previous studies showed that outcome is clearly better when therapists achieved a generally high quality of a therapeutic relationship when they did not shy away from possibly threatening interventions such as confrontations. This ratio of a fruitful alliance and marginally present confrontations in the same session also showed significant correlations with patient’s assessment of alliance and progress in therapy (Figlioli et al., 2009). These findings are also very much in line with Sachse’s metaphor of accumulating, but then also using ‘relationship credits’ and Farrelly’s ‘Provocative Therapy’ (1986), as well as the ‘Intensive Short-Term Dynamic Psychotherapy’ by Davanloo (1980).Aim: The current state of research in the field does not give any answers to questions like how good and bad confrontations can be characterized or what role does the intensity, respectively frequency of confrontations play in the process of psychotherapy.Methods: A sample of 80 therapies of 3 sessions each representing either good or bad outcome was judged moment by moment by independent raters if and how therapists used confrontative interventions. Results / Discussion: The results will be discussed in terms of their implications for the clinical daily work. Preliminary analyses show that successful confrontations are explicitly uttered, short but intense, related to important patients goals in therapy and embedded in prior complementarity.
Resumo:
Tumor budding (single tumor cells or small tumor cell clusters) at the invasion front of colorectal cancer (CRC) is an adverse prognostic indicator linked to epithelial-mesenchymal transition. This study characterized the immunogenicity of tumor buds by analyzing the expression of the major histocompatibility complex (MHC) class I in the invasive tumor cell compartment. We hypothesized that maintenance of a functional MHC-I antigen presentation pathway, activation of CD8+ T-cells, and release of antitumoral effector molecules such as cytotoxic granule-associated RNA binding protein (TIA1) in the tumor microenvironment can counter tumor budding and favor prolonged patient outcome. Therefore, a well-characterized multipunch tissue microarray of 220 CRCs was profiled for MHC-I, CD8, and TIA1 by immunohistochemistry. Topographic expression analysis of MHC-I was performed using whole tissue sections (n = 100). Kirsten rat sarcoma viral oncogene homolog (KRAS) and B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutations, mismatch repair (MMR) protein expression, and CpG-island methylator phenotype (CIMP) were investigated. Our results demonstrated that membranous MHC-I expression is frequently down-regulated in the process of invasion. Maintained MHC-I at the invasion front strongly predicted low-grade tumor budding (P = 0.0004). Triple-positive MHC-I/CD8/TIA1 in the tumor microenvironment predicted early T-stage (P = 0.0031), absence of lymph node metastasis (P = 0.0348), lymphatic (P = 0.0119) and venous invasion (P = 0.006), and highly favorable 5-year survival (90.9% vs 39.3% in triple-negative patients; P = 0.0032). MHC-I loss was frequent in KRAS-mutated, CD8+ CRC (P = 0.0228). No relationship was observed with CIMP, MMR, or BRAF mutation. In conclusion, tumor buds may evade immune recognition through downregulation of membranous MHC-I. A combined profile of MHC-I/CD8/TIA1 improves the prognostic value of antitumoral effector cells and should be preferred to a single marker approach.
Resumo:
Sound knowledge of the spatial and temporal patterns of rockfalls is fundamental for the management of this very common hazard in mountain environments. Process-based, three-dimensional simulation models are nowadays capable of reproducing the spatial distribution of rockfall occurrences with reasonable accuracy through the simulation of numerous individual trajectories on highly-resolved digital terrain models. At the same time, however, simulation models typically fail to quantify the ‘real’ frequency of rockfalls (in terms of return intervals). The analysis of impact scars on trees, in contrast, yields real rockfall frequencies, but trees may not be present at the location of interest and rare trajectories may not necessarily be captured due to the limited age of forest stands. In this article, we demonstrate that the coupling of modeling with tree-ring techniques may overcome the limitations inherent to both approaches. Based on the analysis of 64 cells (40 m × 40 m) of a rockfall slope located above a 1631-m long road section in the Swiss Alps, we illustrate results from 488 rockfalls detected in 1260 trees. We illustrate that tree impact data cannot only be used (i) to reconstruct the real frequency of rockfalls for individual cells, but that they also serve (ii) the calibration of the rockfall model Rockyfor3D, as well as (iii) the transformation of simulated trajectories into real frequencies. Calibrated simulation results are in good agreement with real rockfall frequencies and exhibit significant differences in rockfall activity between the cells (zones) along the road section. Real frequencies, expressed as rock passages per meter road section, also enable quantification and direct comparison of the hazard potential between the zones. The contribution provides an approach for hazard zoning procedures that complements traditional methods with a quantification of rockfall frequencies in terms of return intervals through a systematic inclusion of impact records in trees.
Resumo:
The human turn-taking system regulates the smooth and precise exchange of speaking turns during face-to-face interaction. Recent studies investigated the processing of ongoing turns during conversation by measuring the eye movements of noninvolved observers. The findings suggest that humans shift their gaze in anticipation to the next speaker before the start of the next turn. Moreover, there is evidence that the ability to timely detect turn transitions mainly relies on the lexico-syntactic content provided by the conversation. Consequently, patients with aphasia, who often experience deficits in both semantic and syntactic processing, might encounter difficulties to detect and timely shift their gaze at turn transitions. To test this assumption, we presented video vignettes of natural conversations to aphasic patients and healthy controls, while their eye movements were measured. The frequency and latency of event-related gaze shifts, with respect to the end of the current turn in the videos, were compared between the two groups. Our results suggest that, compared with healthy controls, aphasic patients have a reduced probability to shift their gaze at turn transitions but do not show significantly increased gaze shift latencies. In healthy controls, but not in aphasic patients, the probability to shift the gaze at turn transition was increased when the video content of the current turn had a higher lexico-syntactic complexity. Furthermore, the results from voxel-based lesion symptom mapping indicate that the association between lexico-syntactic complexity and gaze shift latency in aphasic patients is predicted by brain lesions located in the posterior branch of the left arcuate fasciculus. Higher lexico-syntactic processing demands seem to lead to a reduced gaze shift probability in aphasic patients. This finding may represent missed opportunities for patients to place their contributions during everyday conversation.