Numerical models indicate that collective animal behavior may emerge from simple local rules of interaction among the individuals. However, very little is known about the nature of such interaction, ...so that models and theories mostly rely on aprioristic assumptions. By reconstructing the three-dimensional positions of individual birds in airborne flocks of a few thousand members, we show that the interaction does not depend on the metric distance, as most current models and theories assume, but rather on the topological distance. In fact, we discovered that each bird interacts on average with a fixed number of neighbors (six to seven), rather than with all neighbors within a fixed metric distance. We argue that a topological interaction is indispensable to maintain a flock's cohesion against the large density changes caused by external perturbations, typically predation. We support this hypothesis by numerical simulations, showing that a topological interaction grants significantly higher cohesion of the aggregation compared with a standard metric one.
Introduction
In elderly patients, an established treatment for femoral neck fractures is hip hemiarthroplasty (HHA) using the anterolateral approach (ALA). Early postoperative mobilization is crucial ...to reduce perioperative complications. The direct anterior approach (DAA) has been reported to facilitate early recovery of ambulation and is increasingly popular in elective hip surgery but rarely used in femoral neck fractures. The aim was to compare the outcome of the DAA and the ALA in patients treated for femoral neck fracture.
Materials and methods
All HHAs with complete data sets were reviewed from a tertiary public healthcare institution (2013–2020). Propensity score matching was applied to compensate for possible confounders; outcome parameters were perioperative blood loss, postoperative mobility and pain. Secondary outcomes were duration of surgery, length of stay (LOS), complications, reoperation and mortality rates.
Results
There were 237 patients (mean age 85.8 years) available for analysis. The DAA group mobilized earlier during hospitalization (outside patient room: 50.6 vs 38.6%,
p
= 0.01; walking on crutches/walker: 48.1 vs 36.1%,
p
< 0.01), had shorter surgeries (DAA vs ALA: 72.5 vs 89.5 min,
p
< 0.001) and a trend towards fewer complications (32.9% vs 44.9%,
p
= 0.076). Blood loss (286 vs 287 ml), LOS (10.4 vs 9.5 days), pain (cessation of opioid medication: 2.9 vs 3.3 days post-op), revision (2.5 vs 3.2%) or mortality (30-days: 7.6 vs 5.7%) did not differ between patient groups.
Conclusions
DAA for HHA led to earlier in-hospital mobility, shorter surgeries and a tendency towards fewer complications. No advantage was found regarding perioperative blood loss and pain.
AIMIt has been reported that in patients with spinal muscular atrophy (SMA), lower levels of motor function are associated with hyperleptinemia. Additionally, hyperleptinemia has been found to be ...more frequent in underweight SMA patients. Therefore, we aimed to analyze serum leptin levels in patients with SMA. METHODThis was a cross-sectional study of pediatric patients (2-19 years old) with SMA types 2 and 3. The investigations included anthropometric measurements, assessment of pubertal status, motor function evaluation using the Hammersmith Functional Motor Scale - Expanded (HFMSE), and serum leptin levels. RESULTSIn total, 37 patients (22 with type 2 and 15 with type 3 SMA) were included in the study. The male-to-female ratio was 1:1.3 and 62.2% of patients were prepubertal. No statistically significant correlation was found between the HFMSE score and leptin levels, rs(35) = 0.24, p = 0.15. There was, however, a strong positive relationship between the body mass index (BMI) z-score and leptin levels, rs(35) = 0.87, p < 0.001. CONCLUSIONSerum leptin levels do not seem to be a useful marker of disease severity in children and adolescents with types 2 and 3 SMA. As in the general pediatric population, leptin levels are strongly correlated with BMI, which is a surrogate measure of body fat.
Aim To review the clinical experience of children and teens diagnosed with Type 2 diabetes (T2DM) at a paediatric hospital serving a large urban multi‐ethnic population.
Methods Retrospective chart ...review of patients with T2DM followed in the diabetes clinic at the Hospital for Sick Children (HSC) over an 8‐year period. Patients who were included were younger than 18, referred at the onset of diabetes, and where presentation and/or clinical course was ‘typical’ of T2DM.
Results Of 1020 children with diabetes followed at HSC, 4% were identified as having T2DM in 2002. There was a sixfold increase in new cases from 1994 to 2002. The mean age at diagnosis was 13.5 ± 2.2 years (range 8.8–17.5) with a female‐to‐male ratio of 1.7. Most had a first‐ or second‐degree relative with T2DM. There was an overrepresentation of children with T2DM from Asian and African Canadian ethnic groups relative to the regional population. The majority of teens were asymptomatic at presentation, with a smaller number in diabetic ketoacidosis (DKA) at diagnosis. Mean HbA1c at diagnosis was 10 ± 3.4%. Approximately one half of patients were initially treated by diet and exercise with many requiring intensification of therapy over a short period of time.
Conclusions We report a similar increase in T2DM incidence and clinical presentation at HSC to other clinic reports in large North American urban centres. Of note is the high prevalence of children of South/South‐East Asian descent.
The proliferation of devices with Android OS recently facilitated the integration of various consumer electronic devices running Android for novel applications. In this paper the architecture and a ...framework for the development of TV-centric games is presented. These games involve set-top boxes or TV receivers, mobile devices and the Internet towards the creation of an innovative gameplay. The paper discusses the benefits of TV-centric gaming concept, presents several developed game prototypes and gives the first results of user survey with regard to the usability of the concept.
Bird flocking is a striking example of collective animal behaviour. A vivid illustration of this phenomenon is provided by the aerial display of vast flocks of starlings gathering at dusk over the ...roost and swirling with extraordinary spatial coherence. Both the evolutionary justification and the mechanistic laws of flocking are poorly understood, arguably because of a lack of data on large flocks. Here, we report a quantitative study of aerial display. We measured the individual three-dimensional positions in compact flocks of up to 2700 birds. We investigated the main features of the flock as a whole (shape, movement, density and structure) and we discuss these as emergent attributes of the grouping phenomenon. Flocks were relatively thin, of various sizes, but constant proportions. They tended to slide parallel to the ground and, during turns, their orientation changed with respect to the direction of motion. Individual birds kept a minimum distance from each other that was comparable to their wing span. The density within the aggregations was nonhomogeneous, as birds were packed more tightly at the border than the centre of the flock. These results constitute the first set of large-scale data on three-dimensional animal aggregations. Current models and theories of collective animal behaviour can now be tested against these data.
The choice of optimal pressing regime for certain types of substrate is of great importance in production of veneered panels. In this paper, the impact of pressing regime on the bonding strength of ...beech and oak veneers, glued with urea-formaldehyde (UF) adhesive, on medium-density fiberboard (MDF), and moisture-resistant MDF (MR MDF) substrates was examined. The analyses showed a generally higher bond strength with oak veneer compared to beech veneer, which was also the case with regular MDF compared to moisture-resistant MDF. Multivariate analysis of variance (ANOVA) showed that with beech veneer, all of the used regimes produced better results on regular MDF compared to moisture-resistant MDF. In contrast, with oak veneer, the influence of pressing regime had a more noteworthy impact than the type of substrate used. These results indicated that the use of MR MDF as substrate in combination with UF adhesive was inadequate.
Joint aspiration in suspected infected implants is a validated diagnostic method in establishing the diagnosis of prosthetic joint infection (PJI). Cut-off values for synovial leukocyte counts and ...differentials are well described for patients with hip and knee PJI. In 19 failed shoulder implants, a leucocyte count of >12.2 G/L had a sensitivity and specificity of 92% and 100% respectively; A differential of >54% neutrophils had a sensitivity of 100 % and a specificity of 75%.
PDF
