464 research outputs found
A new crack tip element for the phantom-node method with arbitrary cohesive cracks
We have developed a new crack tip element for the phantom-node method. In this method, a crack tip can be placed inside an element. Therefore, cracks can propagate almost independent of the finite element mesh. We developed two different formulations for the three-node triangular element and fournode quadrilateral element, respectively. Although this method is well suited for the one-point quadrature scheme, it can be used with other general quadrature schemes. We provide some numerical examples for some static and dynamic problems
Epidemiology of paediatric renal stone disease: a 22-year single centre experience in the UK
BACKGROUND: Whilst still rare, the incidence of paediatric stone disease is increasing in developed countries and it is important to evaluate the aetiology. We set up a dedicated renal stone service for children combining medical and surgical expertise in 1993 and now have a large case series of children to investigate the epidemiology. METHODS: A retrospective hospital note review of children presenting with kidney stones during the last 22Â years (1993-2015) was conducted. All patients had a comprehensive infective and metabolic screen and were classified as metabolic, infective or idiopathic stone disease. RESULTS: Five hundred eleven patients (322 male) were reviewed. The median age of presentation was 4.4y for males (1Â m-16.6y) and 7.3y (1-18.5y) for females with a median height and weight on the 25th centile for male and on 10th and 25th for female, respectively. One hundred seventy five (34%) had an underlying metabolic abnormality, 112 (22%) had infective stones and 224 (44%) were classified as idiopathic. Of the 175 patients with a metabolic abnormality: 91 (52%) had hypercalciuria (76 persistent and 15 transient), 37 (21%) hyperoxaluria, 38 (22%) cystinuria, 3 (2%) abnormalities in the purine metabolism and the remainder other metabolic abnormalities. Bilateral stones occurred in 27% of the metabolic group compared to 16% in the non-metabolic group (OR 0.2, pâ<â0.05). Urinary tract infection was a common complication (27%) in the metabolic group. CONCLUSIONS: In this paper, we present the largest cohort of paediatric stone disease reported from a developed country giving details on both, clinical and laboratory data. We show that in the majority of the patients there is an identifiable underlying metabolic and/or infective aetiology emphasizing the importance of a full work up to provide adequate treatment and prevent recurrence. Moreover, we show that stone disease in children, in contrast to the adult population, does not seem to be associated with obesity, as children have a weight below average at presentation
Isolated bilateral simplex ureteric ectopia: Bladder capacity as an indicator of continence outcome
INTRODUCTION:
Isolated bilateral simplex ectopic ureters (BSEUs) are rare but pose a therapeutic challenge: ureteric reimplantation alone does not accomplish continence in all. Identifying the patients needing additional procedures for continence early could prevent multiple operations.
OBJECTIVE:
Potential preoperative indicators for postoperative continence are explored in eight BSEU girls without cloacal, anorectal, or spinal anomalies.
STUDY DESIGN:
With institutional approval, all patients with BSEU between 1985 and 2012 were retrospectively reviewed. Cystoscopy determined the site of ureteric ectopia (6 of 16 at the bladder neck [BN], 5 of 16 below the BN, and 5 of 16 in the distal urethra). Bladders were assessed by a combination of ultrasound, urodynamics, micturating cystourethrogram, cystoscopic, and intraoperative observations. Expected bladder capacity for age (EBCA) was calculated by 30 ml + (30 ml Ă age in years) or 38 ml + (2.5 ml Ă age in months) for children greater or less than 2 years, respectively. Continence outcomes were appraised at a minimum of 4 years. The small number of patients precludes credible statistical analysis and therefore raw data are presented.
RESULTS:
Patients underwent cross-trigonal ureteric reimplantation at 1â5.5 years, in five without BN surgery and in three with a YoungâDeesâLeadbetter BN tightening. Of those without BN surgery at reimplantation, four achieved satisfactory continence for their age, but one has had multiple procedures culminating in BN closure, ileocystoplasty, and Mitrofanoff. Among the BN-tightening group, one was in nappies at 4 years, one had residual stress incontinence after two further BN injections, and one proceeded to artificial urinary sphincter after two BN injections. Five patients had significant renal impairment.
DISCUSSION:
Patients with satisfactory continence after reimplantation alone and those needing further procedures tended to differ in their preoperative observations of bladder capacity and apparent BN competence. This study suggests preoperative observations of an empty bladder on serial ultrasound and/or a wide-open BN with small or even moderate bladder capacity at cystoscopy to indicate the need for BN surgery. In contrast, children with bladder filling to at least 30% of expected bladder capacity for age on preoperative ultrasound or apposition of the BN at cystoscopy may achieve satisfactory continence after ureteric reimplantation alone. Bladder capacity as an indicator of BN competence can also be correlated to continence outcomes in previously published series. Polyuria associated with renal impairment can exacerbate the challenge for continence.
CONCLUSION:
Preoperative bladder capacity appears to be an indicator of inherent BN function and a thorough assessment of the urinary tract by cystoscopy, ultrasound, micturating cystourethrogram, and functional imaging may guide the surgeon on the need for BN surgery at the time of ureteric reimplantation. Where continence remains elusive, patients should be counselled that a further BN injection is occasionally of value although more significant BN procedures are required for most
Graphic-based concept retrieval
Two ways of expressing concepts in the context of image retrieval are presented. One, Keypics, is on the side of an image owner, who wants the image itself to be found on the Web; the second, Trittico, is on the side of the image searcher. Both are based on the paradigm of human intermediation for overcoming the semantic gap. Both require tools capable of qualitative analysis, and have been experimented by using persistent homology
Hard Occlusions in Visual Object Tracking
Visual object tracking is among the hardest problems in computer vision, as
trackers have to deal with many challenging circumstances such as illumination
changes, fast motion, occlusion, among others. A tracker is assessed to be good
or not based on its performance on the recent tracking datasets, e.g., VOT2019,
and LaSOT. We argue that while the recent datasets contain large sets of
annotated videos that to some extent provide a large bandwidth for training
data, the hard scenarios such as occlusion and in-plane rotation are still
underrepresented. For trackers to be brought closer to the real-world scenarios
and deployed in safety-critical devices, even the rarest hard scenarios must be
properly addressed. In this paper, we particularly focus on hard occlusion
cases and benchmark the performance of recent state-of-the-art trackers (SOTA)
on them. We created a small-scale dataset containing different categories
within hard occlusions, on which the selected trackers are evaluated. Results
show that hard occlusions remain a very challenging problem for SOTA trackers.
Furthermore, it is observed that tracker performance varies wildly between
different categories of hard occlusions, where a top-performing tracker on one
category performs significantly worse on a different category. The varying
nature of tracker performance based on specific categories suggests that the
common tracker rankings using averaged single performance scores are not
adequate to gauge tracker performance in real-world scenarios.Comment: Accepted at ECCV 2020 Workshop RLQ-TO
Long-Term Visual Object Tracking Benchmark
We propose a new long video dataset (called Track Long and Prosper - TLP) and
benchmark for single object tracking. The dataset consists of 50 HD videos from
real world scenarios, encompassing a duration of over 400 minutes (676K
frames), making it more than 20 folds larger in average duration per sequence
and more than 8 folds larger in terms of total covered duration, as compared to
existing generic datasets for visual tracking. The proposed dataset paves a way
to suitably assess long term tracking performance and train better deep
learning architectures (avoiding/reducing augmentation, which may not reflect
real world behaviour). We benchmark the dataset on 17 state of the art trackers
and rank them according to tracking accuracy and run time speeds. We further
present thorough qualitative and quantitative evaluation highlighting the
importance of long term aspect of tracking. Our most interesting observations
are (a) existing short sequence benchmarks fail to bring out the inherent
differences in tracking algorithms which widen up while tracking on long
sequences and (b) the accuracy of trackers abruptly drops on challenging long
sequences, suggesting the potential need of research efforts in the direction
of long-term tracking.Comment: ACCV 2018 (Oral
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