844 research outputs found
Factors that predict hazard perception in older adult road-users : A systematic review
Background: Older adults are more likely to be at-fault and killed in road crashes, and this has been argued to be due to their declining hazard perception (HP). There has been no comprehensive review on what factors predict this decline in HP ability for older adults. Objectives: The aim of this systematic review is to identify any predictors of HP in older adults across all road-user types. Data Sources: The search was indexed in the Medline, PsycINFO, and Scopus during January 2022. Studies had to be peer reviewed and written in English language. Participants had to be road-users over the age of 60. Studies had to investigate a relationship between a predictor and HP. Results: 21 articles met the inclusion criteria, 20 for drivers and one for pedestrians. Seven predictors were examined. Results suggested that driving experience and auditory distraction were the most consistent predictors of HP. HP training for drivers significantly improved HP. Results were mixed for visual abilities, cognitive abilities, and age. Training for pedestrians was not a significant predictor of HP. Limitations: Grey literature was not reviewed. Conclusions: Whilst results related to age were mixed, most studies suggested that advancing age is associated with HP decline. Driving experience appeared to be a protective factor against decline in HP. Contrast and motion sensitivity may be important in identifying at-risk drivers. Cognitive function was not a consistent predictor of HP. Auditory distractors consistently negatively impacted HP. Results indicated that there could be potential benefits of HP training. There is a dearth of research into HP in vulnerable road user types. Implications: By identifying the predictors of HP, road safety strategies such as holistic training programs could be developed to assist with keeping older adult road-users safe. Future research is necessary to explore HP in older pedestrians, cyclists, and motorcyclists
Shaken Granular Lasers
Granular materials have been studied for decades, also driven by industrial
and technological applications. These very simple systems, composed by
agglomerations of mesoscopic particles, are characterized, in specific regimes,
by a large number of metastable states and an extreme sensitivity (e.g., in
sound transmission) on the arrangement of grains; they are not substantially
affected by thermal phenomena, but can be controlled by mechanical
solicitations. Laser emission from shaken granular matter is so far unexplored;
here we provide experimental evidence that it can be affected and controlled by
the status of motion of the granular, we also find that competitive random
lasers can be observed. We hence demonstrate the potentialities of gravity
affected moving disordered materials for optical applications, and open the
road to a variety of novel interdisciplinary investigations, involving modern
statistical mechanics and disordered photonics.Comment: 4 pages, 3 figures. To be published in Physical Review Letter
Network dilution and asymmetry in an efficient brain
The ultimate goal of neuroscience is to ultimately understand how the brain functions. The advancement of brain imaging shows us how the brain continuously alternates complex activity patterns and experimentally reveals how these patterns are responsible for memory, association, reasoning, and countless other tasks. Two fundamental parameters, dilution (the number of connections per node), and symmetry (the number of bidirectional connections of the same weight) characterise two fundamental features underlying the networks that connect the single neurons in the brain and generate these patterns. Mammalian brains show large variations of dilution, and mostly asymmetric connectivity, unfortunately the advantages which drove evolution to these state of network dilution and asymmetry are still unknown. Here, we studied the effects of symmetry and dilution on a discrete-time recurrent neural network with McCulloch–Pitts neurons. We use an exhaustive approach, in which we probe all possible inputs for several randomly connected neuron networks with different degrees of dilution and symmetry. We find an optimum value for the synaptic dilution and symmetry, which turns out to be in striking quantitative agreement with what previous researchers have found in the brain cortex, neocortex and hippocampus. The diluted asymmetric brain shows high memory capacity and pattern recognition speed, but most of all it is the less energy-consumptive with respect to fully connected and symmetric network topologies
Crystallographic studies on complexes between retinoids and plasma retinol-binding protein.
The three-dimensional structures of complexes between bovine plasma retinol-binding protein (RBP) and three retinol analogs with different end groups (fenretinide, all-trans retinoic acid, and axerophthene) have been determined to 1.8-1.9-A resolution. Their models are very similar to that of the bovine retinol.RBP complex: the root mean square deviations between equivalent alpha-carbons in the two proteins range from 0.17 to 0.24 A. The retinoid molecules fit in the beta-barrel cavity assuming the same conformation of the vitamin, and the substitutions have no consequences on the overall protein structure. While confirming that an intact hydroxyl end group is not an absolute requirement for a correct retinoid binding to RBP, this study has shown the occurrence of conformational changes, although limited, in the rather flexible loop region at the entrance of the beta-barrel upon fenretinide and retinoic acid binding. These changes are suitable for accommodating the end groups of the above retinoids. Instead, no such changes have been revealed in RBP complexed with axerophthene, a retinol analog bearing a hydrogen atom in place of the hydroxyl end group. The protein conformational changes in the above loop region, the steric hindrance of bulky end groups of bound retinoids, and the lack of the retinol hydroxyl group appear to be responsible for the possible reduced affinity of retinoids for RBP relative to retinol and, at the same time, for the abolished or reduced affinity of retinoid.RBP complexes for transthyretin relative to retinol-RBP
Probing the structure of copper(II)-casiopeina type coordination complexes [Cu(O-O)(N-N)]+ by EPR and ENDOR spectroscopy
Although copper based complexes have been widely used in homogeneous catalysis, more recently they are attracting considerable attention as pharmaceutical therapeutic agents. Of paramount importance in their efficacy of use is their structure and electronic properties, which can be thoroughly probed using advanced EPR techniques. In this study, a series of [Cu(acac)(N-N)]+ Casiopeina type complexes were investigated, bearing a series of diimine N-N ligands (including bipy, phen, Py-bipy and dppz). All complexes displayed rhombic g and CuA tensors, although the extent of rhombicity was dependent on the N-N ligand. Greater Cu(II)-N2 in-plane distortion, away from the square planar arrangement, was detected by CW W-band EPR for the smaller bipy and phen ligands compared to the larger Py-bipy and dppz ligands. Changes in ligand spin density distributions (over the 1H and 14N nuclei) were revealed by CW Q-band ENDOR. The largest components of the 1H imine and 14N hyperfine coupling decreased as the ligand size increased, following the trend bipy > phen > Py-bipy > dppz. These results indicate how even small structural and electronic (spin density) perturbations within the Casiopeina family of Cu(II) complexes can be probed by advanced EPR methods
A P2P Platform for real-time multicast video streaming leveraging on scalable multiple descriptions to cope with bandwidth fluctuations
In the immediate future video distribution applications will increase their diffusion thanks tothe ever-increasing user capabilities and improvements in the Internet access speed and performance.The target of this paper is to propose a content delivery system for real-time streaming services based ona peer-to-peer approach that exploits multicast overlay organization of the peers to address thechallenges due to bandwidth heterogeneity. To improve reliability and flexibility, video is coded using ascalable multiple description approach that allows delivery of sub-streams over multiple trees andallows rate adaptation along the trees as the available bandwidth changes. Moreover, we have deployeda new algorithm for tree-based topology management of the overlay network. In fact, tree based overlaynetworks better perform in terms of end-to-end delay and ordered delivery of video flow packets withrespect to mesh based ones. We also show with a case study that the proposed system works better thansimilar systems using only either multicast or multiple trees
Elevated Concentrations of Liver Enzymes and Ferritin Identify a New Phenotype of Insulin Resistance: Effect of Weight Loss After Gastric Banding
BACKGROUND: Several studies have associated elevated liver enzymes (LFTs), obesity, and type 2 diabetes (T2DM), and a link has been established between insulin resistance (IR) and elevated ferritin concentrations. We examined the relationship between LFTs, ferritin, and IR in morbid obese subjects and the effect of weight loss after bariatric surgery. METHODS: We measured liver enzymes, ferritin, insulin resistance, and glucose tolerance (by OGTT) in 159 morbid obese subjects (BMI = 44.4 +/- 0.4 kg/m(2)) at baseline, 6 months and 1 year after laparoscopic-adjustable-gastric banding (LAGB). Subjects were divided in two groups: increased LFTs (ALT > 30; AST/ALT < 1) vs. normal LFTs. RESULTS: A large proportion of morbid obese subjects had increased LFTs (44%) which were associated with increased IR and ferritin, suggesting potential liver disease. A majority of the morbidly obese with increased LFTs, IGT, and T2DM, were male and had almost double ferritin concentrations, strongly correlated with ALT (r = 0.43, p < 0.0001). Both ferritin and ALT correlated with waist circumference and IR. One year after, LAGB glucose tolerance improved, LFTs and IR were reduced; ferritin did not change significantly, but was still correlated with IR. CONCLUSIONS: Ferritin may be an additional useful marker for more severe hepatic IR
Functional characterization of the type I toxin Lpt from Lactobacillus rhamnosus by fluorescence and atomic force microscopy
Lpt is a 29 amino acid long type I toxin identified in the plasmid DNA of wild Lactobacillus rhamnosus strains isolated from food. We previously reported that transcription of the encoding gene was upregulated under nutritional starvation conditions mimicking cheese ripening environment. The heterologous expression of the Lpt peptide in E. coli resulted in cell growth inhibition, nucleoid condensation and compromised integrity of the cell membrane. Fusion of the Lpt peptide with the fluorescent protein mCherry allowed to visualize the accumulation of the peptide into the membrane, while mutagenesis experiments showed that either the insertion of a negatively charged amino acid into the hydrophobic a-helix or deletion of the hydrophilic C-terminal region, leads to a non-toxic peptide. AFM imaging of Lpt expressing E. coli cells has revealed the presence of surface defects that are compatible with the loss of portions of the outer membrane bilayer. This observation provides support for the so-called "carpet" model, by which the Lpt peptide is supposed to destabilize the phospholipid packing through a detergent-like mechanism leading to the removal of small patches of bilayer through micellization
Collective behavior and self-organization in neural rosette morphogenesis
Neural rosettes develop from the self-organization of differentiating human pluripotent stem cells. This process mimics the emergence of the embryonic central nervous system primordium, i.e., the neural tube, whose formation is under close investigation as errors during such process result in severe diseases like spina bifida and anencephaly. While neural tube formation is recognized as an example of self-organization, we still do not understand the fundamental mechanisms guiding the process. Here, we discuss the different theoretical frameworks that have been proposed to explain self-organization in morphogenesis. We show that an explanation based exclusively on stem cell differentiation cannot describe the emergence of spatial organization, and an explanation based on patterning models cannot explain how different groups of cells can collectively migrate and produce the mechanical transformations required to generate the neural tube. We conclude that neural rosette development is a relevant experimental 2D in-vitro model of morphogenesis because it is a multi-scale self-organization process that involves both cell differentiation and tissue development. Ultimately, to understand rosette formation, we first need to fully understand the complex interplay between growth, migration, cytoarchitecture organization, and cell type evolution
Neoadjuvant eribulin mesylate following anthracycline and taxane in triple negative breast cancer: Results from the HOPE study
Background Eribulin mesylate (E) is indicated for metastatic breast cancer patients previously treated with anthracycline and taxane. We argued that E could also benefit patients eligible for neoadjuvant chemotherapy. Methods Patients with primary triple negative breast cancer 2 cm received doxorubicin 60 mg/m2 and paclitaxel 200 mg/m2 x 4 cycles (AT) followed by E 1.4 mg/m2 x 4 cycles. Primary endpoint was pathological complete response (pCR) rate; secondary and explorative endpoints included clinical/metabolic response rates and safety, and biomarker analysis, respectively. Using a two-stage Simon design, 43 patients were to be included provided that 4 of 13 patients had achieved pCR in the first stage of the study. Results In stage I of the study 13 women were enrolled, median age 43 years, tumor size 2–5 cm in 9/13 (69%), positive nodal status in 8/13 (61%). Main grade 3 adverse event was neutropenia (related to AT and E in 4 and 2 cases, respectively). AT followed by E induced clinical complete + partial responses in 11/13 patients (85%), pCR in 3/13 (23%). Median measurements of maximum standardized uptake value (SUVmax) resulted 13, 3, and 1.9 at baseline, after AT and E, respectively. Complete metabolic response (CMR) occurred after AT and after E in 2 and 3 cases, respectively. Notably, 2 of the 5 (40%) patients with CMR achieved pCR at surgery. Immunostaining of paired pre-/post-treatment tumor specimens showed a reduction of β-catenin, CyclinD1, Zeb-1, and c-myc expression, in the absence of N-cadherin modulation. The study was interrupted at stage I due to the lack of the required patients with pCR. Conclusions Despite the early study closure, preoperative E following AT showed clinical and biological activity in triple negative breast cancer patients. Furthermore, the modulation of β-catenin pathway core proteins, supposedly outside the domain of epithelial–mesenchymal transition, claims for further investigation. Trial registration EU Clinical Trial Register, EudraCT number 2012-004956-12
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