13 resultados para FREQUENCY APPROACH

em BORIS: Bern Open Repository and Information System - Berna - Suiça


Relevância:

30.00% 30.00%

Publicador:

Resumo:

The systemic capillary leak syndrome (SCLS), also known as Clarkson’s disease, is a life-threatening disorder of unknown cause. It is characterised by recurrent acute episodes of hypotension, weight gain and generalised oedema with haemoconcentration and hypoproteinaemia caused by paroxysmal capillary hyperpermeability with a shift of plasma fluid from the intravascular to the interstitial space. We report the case of a 40-year-old woman with chronic SCLS treated with high-dose intravenous immunoglobulins, after a prophylactic therapy with theophylline and terbutaline was poorly tolerated and failed to decrease the frequency and severity of the attacks sufficiently.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

For the first time we present a multi-proxy data set for the Russian Altai, consisting of Siberian larch tree-ring width (TRW), latewood density (MXD), δ13C and δ18O in cellulose chronologies obtained for the period 1779–2007 and cell wall thickness (CWT) for 1900–2008. All of these parameters agree well between each other in the high-frequency variability, while the low-frequency climate information shows systematic differences. The correlation analysis with temperature and precipitation data from the closest weather station and gridded data revealed that annual TRW, MXD, CWT, and δ13C data contain a strong summer temperature signal, while δ18O in cellulose represents a mixed summer and winter temperature and precipitation signal. The temperature and precipitation reconstructions from the Belukha ice core and Teletskoe lake sediments were used to investigate the correspondence of different independent proxies. Low frequency patterns in TRW and δ13C chronologies are consistent with temperature reconstructions from nearby Belukha ice core and Teletskoe lake sediments showing a pronounced warming trend in the last century. Their combination could be used for the regional temperature reconstruction. The long-term δ18O trend agrees with the precipitation reconstruction from the Teletskoe lake sediment indicating more humid conditions during the twentieth century. Therefore, these two proxies could be combined for the precipitation reconstruction.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Alternans of cardiac action potential duration (APD) is a well-known arrhythmogenic mechanism which results from dynamical instabilities. The propensity to alternans is classically investigated by examining APD restitution and by deriving APD restitution slopes as predictive markers. However, experiments have shown that such markers are not always accurate for the prediction of alternans. Using a mathematical ventricular cell model known to exhibit unstable dynamics of both membrane potential and Ca2+ cycling, we demonstrate that an accurate marker can be obtained by pacing at cycle lengths (CLs) varying randomly around a basic CL (BCL) and by evaluating the transfer function between the time series of CLs and APDs using an autoregressive-moving-average (ARMA) model. The first pole of this transfer function corresponds to the eigenvalue (λalt) of the dominant eigenmode of the cardiac system, which predicts that alternans occurs when λalt≤−1. For different BCLs, control values of λalt were obtained using eigenmode analysis and compared to the first pole of the transfer function estimated using ARMA model fitting in simulations of random pacing protocols. In all versions of the cell model, this pole provided an accurate estimation of λalt. Furthermore, during slow ramp decreases of BCL or simulated drug application, this approach predicted the onset of alternans by extrapolating the time course of the estimated λalt. In conclusion, stochastic pacing and ARMA model identification represents a novel approach to predict alternans without making any assumptions about its ionic mechanisms. It should therefore be applicable experimentally for any type of myocardial cell.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

BACKGROUND: The term 'isolated extraordinary daytime urinary frequency' designates an abnormally increased diurnal frequency of painless urination in a completely toilet-trained child with normal urinalysis. METHODS: We report the history of 26 children (16 boys and 10 girls; aged between 4.1 and 10 years) who were referred to us between 2002 and 2006 and subsequently diagnosed with this condition. RESULTS: Possible psychosocial problems, or recent emotional stressors, were disclosed in the majority of the children: recent (36 months or less) asylum seekers (n = 9), school-related problems (n = 4), parental divorce (n = 2) or death of the mother (n = 1). Possible dietary causes were observed in 9 patients: oxalate-rich beverages (n = 5) and liberal ingestion of 'acidic' juices (n = 4). A diet low in oxalates was recommended when children were consuming large quantities of oxalate-rich beverages; and a diet low in acidic juice was recommended in those liberally ingesting acidic juices. Reassurance and observation were the approach in the remaining cases. The median duration of the symptoms was 5 months. A longer (p < 0.05) duration was noted in children of asylum seekers. CONCLUSIONS: This functional condition is easily identifiable, but often under- or misdiagnosed. Confounding the condition might result in redundant investigation.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The frequency of large-scale heavy precipitation events in the European Alps is expected to undergo substantial changes with current climate change. Hence, knowledge about the past natural variability of floods caused by heavy precipitation constitutes important input for climate projections. We present a comprehensive Holocene (10,000 years) reconstruction of the flood frequency in the Central European Alps combining 15 lacustrine sediment records. These records provide an extensive catalog of flood deposits, which were generated by flood-induced underflows delivering terrestrial material to the lake floors. The multi-archive approach allows suppressing local weather patterns, such as thunderstorms, from the obtained climate signal. We reconstructed mainly late spring to fall events since ice cover and precipitation in form of snow in winter at high-altitude study sites do inhibit the generation of flood layers. We found that flood frequency was higher during cool periods, coinciding with lows in solar activity. In addition, flood occurrence shows periodicities that are also observed in reconstructions of solar activity from C-14 and Be-10 records (2500-3000, 900-1200, as well as of about 710, 500, 350, 208 (Suess cycle), 150, 104 and 87 (Gleissberg cycle) years). As atmospheric mechanism, we propose an expansion/shrinking of the Hadley cell with increasing/decreasing air temperature, causing dry/wet conditions in Central Europe during phases of high/low solar activity. Furthermore, differences between the flood patterns from the Northern Alps and the Southern Alps indicate changes in North Atlantic circulation. Enhanced flood occurrence in the South compared to the North suggests a pronounced southward position of the Westerlies and/or blocking over the northern North Atlantic, hence resembling a negative NAO state (most distinct from 4.2 to 2.4 kyr BP and during the Little Ice Age). South-Alpine flood activity therefore provides a qualitative record of variations in a paleo-NAO pattern during the Holocene. Additionally, increased South Alpine flood activity contrasts to low precipitation in tropical Central America (Cariaco Basin) on the Holocene and centennial time scale. This observation is consistent with a Holocene southward migration of the Atlantic circulation system, and hence of the ITCZ, driven by decreasing summer insolation in the Northern hemisphere, as well as with shorter-term fluctuations probably driven by solar activity. (C) 2013 Elsevier Ltd. All rights reserved.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

One of the main problems of flood hazard assessment in ungauged or poorly gauged basins is the lack of runoff data. In an attempt to overcome this problem we have combined archival records, dendrogeomorphic time series and instrumental data (daily rainfall and discharge) from four ungauged and poorly gauged mountain basins in Central Spain with the aim of reconstructing and compiling information on 41 flash flood events since the end of the 19th century. Estimation of historical discharge and the incorporation of uncertainty for the at-site and regional flood frequency analysis were performed with an empirical rainfall–runoff assessment as well as stochastic and Bayesian Markov Chain Monte Carlo (MCMC) approaches. Results for each of the ungauged basins include flood frequency, severity, seasonality and triggers (synoptic meteorological situations). The reconstructed data series clearly demonstrates how uncertainty can be reduced by including historical information, but also points to the considerable influence of different approaches on quantile estimation. This uncertainty should be taken into account when these data are used for flood risk management.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

PURPOSE To analyze the frequency of perforation of the sinus membrane during maxillary sinus floor elevation (SFE) and to assess possible risk factors. MATERIALS AND METHODS Seventy-seven cases of SFE performed with a lateral window approach were evaluated retrospectively. Clinical and radiographic variables potentially influencing the risk of sinus membrane perforation were evaluated and divided into patient-related factors (age, sex, smoking habit); surgery-related factors (type of surgical approach, side, units, sites, and technique of osteotomy); and maxillary sinus-related factors (presence and height of septum, height of residual ridge, thickness of lateral sinus wall, width of antrum, and thickness and status of sinus membrane). RESULTS The following factors presented with at least a 10% difference in rates of perforations: smokers (46.2%) versus nonsmokers (23.4%), simultaneous (32%) versus staged (18.5%) approach, mixed premolar-molar sites (41.2%) versus premolar-only sites (16.7%) versus molar-only sites (26.2%), presence of septa (42.9%) versus no septa (23.8%), and minimum height of residual ridge ≤4 mm (34.2%) versus > 4 mm (20.5%). These same parameters, except minimum height of residual ridge, also showed an odds ratio above 2. However, none of the comparisons reached statistical significance. CONCLUSION The present study failed to demonstrate any factor that statistically significantly increased the risk of sinus membrane perforation during SFE using the lateral window approach.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

BACKGROUND Acetabular fractures and surgical interventions used to treat them can result in nerve injuries. To date, only small case studies have tried to explore the frequency of nerve injuries and their association with patient and treatment characteristics. High-quality data on the risk of traumatic and iatrogenic nerve lesions and their epidemiology in relation to different fracture types and surgical approaches are lacking. QUESTIONS/PURPOSES The purpose of this study was to determine (1) the proportion of patients who develop nerve injuries after acetabular fracture; (2) which fracture type(s) are associated with increased nerve injury risk; and (3) which surgical approach was associated with the highest proportion of patients developing nerve injuries using data from the German Pelvic Trauma Registry. Two secondary aims were (4) to assess hospital volume-nerve-injury relationship; and (5) internal data validity. METHODS Between March 2001 and June 2012, 2236 patients with acetabular fractures were entered into a prospectively maintained registry from 29 hospitals; of those, 2073 (92.7%) had complete records on the endpoints of interest in this retrospective study and were analyzed. The neurological status in these patients was captured at their admission and at the discharge. A total of 1395 of 2073 (67%) patients underwent surgery, and the proportions of intervention-related and other hospital-acquired nerve injuries were obtained. Overall proportions of patients developing nerve injuries, risk based on fracture type, and risk of surgical approach type were analyzed. RESULTS The proportion of patients being diagnosed with nerve injuries at hospital admission was 4% (76 of 2073) and at discharge 7% (134 or 2073). Patients with fractures of the "posterior wall" (relative risk [RR], 2.0; 95% confidence interval [CI], 1.4-2.8; p=0.001), "posterior column and posterior wall" (RR, 2.9; CI, 1.6-5.0; p=0.002), and "transverse+posterior wall" fracture (RR, 2.1; CI, 1.3-3.5; p=0.010) were more likely to have nerve injuries at hospital discharge. The proportion of patients with intervention-related nerve injuries and that of patients with other hospital-acquired nerve injuries was 2% (24 of 1395 and 46 of 2073, respectively). They both were associated with the Kocher-Langenbeck approach (RR, 3.0; CI, 1.4-6.2; p=0.006; and RR, 2.4; CI, 1.4-4.3; p=0.004, respectively). CONCLUSIONS Acetabular fractures with the involvement of posterior wall were most commonly accompanied with nerve injuries. The data suggest also that Kocher-Langenbeck approach to the pelvic ring is associated with a higher risk of perioperative nerve injuries. Trauma surgeons should be aware of common nerve injuries, particularly in posterior wall fractures. The results of the study should help provide patients with more exact information on the risk of perioperative nerve injuries in acetabular fractures. LEVEL OF EVIDENCE Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

BACKGROUND The copy number variation (CNV) in beta-defensin genes (DEFB) on human chromosome 8p23 has been proposed to contribute to the phenotypic differences in inflammatory diseases. However, determination of exact DEFB CN is a major challenge in association studies. Quantitative real-time PCR (qPCR), paralog ratio tests (PRT) and multiplex ligation-dependent probe amplification (MLPA) have been extensively used to determine DEFB CN in different laboratories, but inter-method inconsistencies were observed frequently. In this study we asked which one is superior among the three methods for DEFB CN determination. RESULTS We developed a clustering approach for MLPA and PRT to statistically correlate data from a single experiment. Then we compared qPCR, a newly designed PRT and MLPA for DEFB CN determination in 285 DNA samples. We found MLPA had the best convergence and clustering results of the raw data and the highest call rate. In addition, the concordance rates between MLPA or PRT and qPCR (32.12% and 37.99%, respectively) were unacceptably low with underestimated CN by qPCR. Concordance rate between MLPA and PRT (90.52%) was high but PRT systematically underestimated CN by one in a subset of samples. In these samples a sequence variant which caused complete PCR dropout of the respective DEFB cluster copies was found in one primer binding site of one of the targeted paralogous pseudogenes. CONCLUSION MLPA is superior to PRT and even more to qPCR for DEFB CN determination. Although the applied PRT provides in most cases reliable results, such a test is particularly sensitive to low-frequency sequence variations preferably accumulating in loci like pseudogenes which are most likely not under selective pressure. In the light of the superior performance of multiplex assays, the drawbacks of such single PRTs could be overcome by combining more test markers.

Relevância:

30.00% 30.00%

Publicador:

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.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

We present a power-scalable approach for yellow laser-light generation based on standard Ytterbium (Yb) doped fibers. To force the cavity to lase at 1154 nm, far above the gain-maximum, measures must be taken to fulfill lasing condition and to suppress competing amplified spontaneous emission (ASE) in the high-gain region. To prove the principle we built a fiber-laser cavity and a fiber-amplifier both at 1154 nm. In between cavity and amplifier we suppressed the ASE by 70 dB using a fiber Bragg grating (FBG) based filter. Finally we demonstrated efficient single pass frequency doubling to 577 nm with a periodically poled lithium niobate crystal (PPLN). With our linearly polarized 1154 nm master oscillator power fiber amplifier (MOFA) system we achieved slope efficiencies of more than 15 % inside the cavity and 24 % with the fiber-amplifier. The frequency doubling followed the predicted optimal efficiency achievable with a PPLN crystal. So far we generated 1.5 W at 1154nm and 90 mW at 577 nm. Our MOFA approach for generation of 1154 nm laser radiation is power-scalable by using multi-stage amplifiers and large mode-area fibers and is therefore very promising for building a high power yellow laser-light source of several tens of Watt.