548 research outputs found
Convergence Analysis of a Fully Discrete Family of Iterated Deconvolution Methods for Turbulence Modeling with Time Relaxation
We present a general theory for regularization models of the Navier-Stokes equations based on the Leray deconvolution model with a general deconvolution operator designed to fit a few important key properties. We provide examples of this type of operator, such as the (modified) Tikhonov-Lavrentiev and (modified) Iterated Tikhonov-Lavrentiev operators, and study their mathematical properties. An existence theory is derived for the family of models and a rigorous convergence theory is derived for the resulting algorithms. Our theoretical results are supported by numerical testing with the Taylor-Green vortex problem, presented for the special operator cases mentioned above
Identifying teeth and tooth fragments from digital 3D models
Dental anatomy is an essential skill for human identification in forensic odontology. With the advent of technology enabling virtual autopsies, there is scope for virtual consultation by forensic odontologists especially when the expertise is unavailable but needed in zones of conflict or disasters. This study aimed to investigate potential benefits and challenges of identifying intact and damaged teeth from 3D scanned digital models. Ten 3D tooth models – nine permanent and deciduous human teeth and one animal tooth were uploaded on a hosting platform. A 3-part survey was circulated among 60 forensic odontologists with questions about demography (P1), tooth identification of the scanned 3D models (P2) and the perceived usefulness of 3D models for tooth identification (P3). This was the first time that a survey required the identification of individual human teeth (intact or not) and animal tooth combined. The response rate for study participation was 58%. Substantial agreement among participants was seen in the determination of tooth classification (i.e., molars, premolars) or non-human and tooth within the same tooth class (i.e., lateral incisors, second molar) (both k=0.61). The least agreement (k=0.21) was seen in identification of tooth according to the FDI notation with a mean accuracy of 0.34. While most responders correctly identified the animal tooth, most incorrect responses were seen in the identifica-tion of the intact third molar. While 3D-scanned teeth have the potential to be identified virtually, fo-rensic odontologists should continuously test their skills in tooth morphology and dental anatomy of humans (damaged or not) and animals
Identifying teeth and tooth fragments from digital 3D models
Dental anatomy is an essential skill for human identification in forensic odontology. With the advent of technology enabling virtual autopsies, there is scope for virtual consultation by forensic odontologists especially when the expertise is unavailable but needed in zones of conflict or disasters. This study aimed to investigate potential benefits and challenges of identifying intact and damaged teeth from 3D scanned digital models. Ten 3D tooth models – nine permanent and deciduous human teeth and one animal tooth were uploaded on a hosting platform. A 3-part survey was circulated among 60 forensic odontologists with questions about demography (P1), tooth identification of the scanned 3D models (P2) and the perceived usefulness of 3D models for tooth identification (P3). This was the first time that a survey required the identification of individual human teeth (intact or not) and animal tooth combined. The response rate for study participation was 58%. Substantial agreement among participants was seen in the determination of tooth classification (i.e., molars, premolars) or non-human and tooth within the same tooth class (i.e., lateral incisors, second molar) (both k=0.61). The least agreement (k=0.21) was seen in identification of tooth according to the FDI notation with a mean accuracy of 0.34. While most responders correctly identified the animal tooth, most incorrect responses were seen in the identifica-tion of the intact third molar. While 3D-scanned teeth have the potential to be identified virtually, fo-rensic odontologists should continuously test their skills in tooth morphology and dental anatomy of humans (damaged or not) and animals
Microplastic exposure increases predictability of predator avoidance strategies in hermit crabs
The contamination of natural systems with plastic debris has become one of the most pressing global environmental issues. Microplastics (MPs) are of particular concern because their ubiquity and small size make them available for ingestion by a range of aquatic biota. MP exposure studies are hence proliferating rapidly but are typically limited to the analyses of population-level responses in toxicity endpoints across treatments. Potential contaminant-induced alterations in behavioural patterns, however, could manifest on numerous levels of variation: at the population-level, between individuals and within individuals. Here, we used repeated measures on startle response durations – a risk-avoidance mechanism – in European hermit crabs, Pagurus bernhardus, to measure behavioural responses to MP exposure across multiple levels of variation. We found that MP exposure led to a significant decrease of startle duration at the population-level as well as a reduction of intra-individual variation. In other words, crabs became less risk averse on average and their behaviour became more predictable with increasing MP concentrations. Collectively, our findings indicate that MP pollution might increase susceptibility to predation in hermit crabs
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Environmental conditions are poor predictors of immature white shark Carcharodon carcharias occurrences on coastal beaches of eastern Australia
Understanding and predicting the distribution of organisms in heterogeneous environments is a fundamental ecological question and a requirement for sound management. To implement effective conservation strategies for white shark Carcharodon carcharias populations, it is imperative to define drivers of their movement and occurrence patterns and to protect critical habitats. Here, we acoustically tagged 444 immature white sharks and monitored their presence in relation to environmental factors over a 3 yr period (2016-2019) using an array of 21 iridium satellite-linked (VR4G) receivers spread along the coast of New South Wales, Australia. Results of generalized additive models showed that all tested predictors (month, time of day, water temperature, tidal height, swell height, lunar phase) had a significant effect on shark occurrence. However, collectively, these predictors only explained 1.8% of deviance, suggesting that statistical significance may be rooted in the large sample size rather than biological importance. On the other hand, receiver location, which captures geographic fidelity and local conditions not captured by the aforementioned environmental variables, explained a sizeable 17.3% of deviance. Sharks tracked in this study hence appear to be tolerant to episodic changes in environmental conditions, and movement patterns are likely related to currently undetermined, location-specific habitat characteristics or biological components, such as local currents, prey availability or competition. Importantly, we show that performance of VR4G receivers can be strongly affected by local environmental conditions, and provide an example of how a lack of range test controls can lead to misinterpretation and erroneous conclusions of acoustic detection data.</jats:p
Minimally invasive treatment of urinary fistulas using n-butyl-2-cyanoacrylate : a valid first option
BACKGROUND:
A few single case reports and only one clinical series have been published so far about the use of N-butyl-2-cyanoacrylate in the treatment of urinary fistulas persisting after conventional urinary drainage.
CASE PRESENTATION:
We treated five patients with a mean age of 59.2 years presenting iatrogenic urinary fistulas which persisted following conventional drainage manouvres. There were 3 calyceal fistulas following open, laparoscopic and robotic removal of renal lesions respectively, one pelvic fistula after orthotopic ileal neobladder and a bilateral dehiscence of uretero-sigmoidostomy. We used open-end catheters of different sizes adopting a retrograde endoscopic approach for cyanoacrylate injection in the renal calyces, while a descending percutaneous approach via the pelvic drain tract and bilateral nephrostomies respectively was used for the pelvic fistulas. Fluoroscopic control was always used during the occlusion procedures. The amount of adhesive injected ranged between 2 and 5 cc and in one case the procedure was repeated. With a median follow-up of 11 months we observed clinical and radiological resolution in 4 cases (80%), while a recurrent and infected calyceal fistula after laparoscopic thermal renal damage during tumor enucleoresection required nephrectomy. No significant complications were documented.
CONCLUSIONS:
In an attempt to spare further challenging surgery in patients that had been already operated on recently, minimally invasive occlusion of persistent urinary fistulas with N-butyl-2-cyanoacrylate represents a valid first line treatment, justified in cases when the urinary output is not excessive and there is a favorable ratio between the length and diameter of the fistulous tract
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