Kinetic model for international trade allowing transfer of individuals.

We propose a kinetic model to describe trade among different populations, living in different countries. The interaction rules are assumed depending on the trading propensity of each population and also on non-deterministic (random) effects. Moreover, the possible transfers of individuals from one country to another are also taken into account, by means of suitable Boltzmann-type operators. Consistent macroscopic equations for number density and mean wealth of each country are derived from the kinetic equations, and the effects of transfers on their equilibrium values are commented on. Finally, a suitable continuous trading limit is considered, leading to a simpler system of Fokker-Planck-type kinetic equations, with specific contributions accounting for transfers. This article is part of the theme issue 'Kinetic exchange models of societies and economies'.

A 'Fingerprint' of locomotor maturation: Motor development descriptors, reference development bands and data-set.

BACKGROUND: When aiming at studying and monitoring locomotor development in childhood, innovative indexes for the characterization of motor control performance and wearable technologies have highlighted the potential of significant advances. In particular, quantitative assessment of motor performance during natural walking (NW) and tandem walking (TW) has been proposed to highlight manifestations of motor automaticity and complexity, respectively. RESEARCH QUESTION: This work aims at providing a quantitative overview of metrics characterizing locomotor maturation in a typically developing population, by analysing NW and TW. The final goal is to propose a novel graphical representation of motor development from childhood to adulthood, providing metrics for quantitative assessment with reference bands and data-set, supporting data interpretation and longitudinal assessment. METHODS: 112 typically developing participants (age groups: 6-, 7-, 8-, 9-, 10-, 15-, and 25 years) walked in NW and in TW at self-selected speed. 3D acceleration and angular velocity of lower trunk and shanks were collected. Temporal parameters, their variability, and nonlinear metrics characterizing human movement (harmonic ratio, short-term Lyapunov exponents, multiscale entropy, and recurrence quantification analysis) were calculated. Effect of age was analysed on the different parameters and a graphical polar plot was defined to represent parameters that showed age effect in at least one of the two tasks. RESULTS: Age effect was shown on temporal parameters, their variability, multiscale entropy and recurrence quantification analysis. These parameters were selected for monitoring locomotor development and presented on an ad-hoc designed polar plot showing age-group reference bands. SIGNIFICANCE: Graphic results outline locomotor differences with maturation at first glance. The patterns in NW and TW allow to characterize specific aspects of locomotor maturation, to evaluate in which area changes occur and towards which direction, depending on the task. The novel database containing participants' raw collected data is made available as additional result of the present study.

Changes of human movement complexity during maturation: quantitative assessment using multiscale entropy.

Movement complexity can be defined as the capability of using different strategies to accomplish a specific task and is expected to increase with maturation, reaching its highest level in adulthood.Multiscale Entropy (MSE) has been proposed to estimate complexity on different kinematic signals, at different time scales. When applied on trunk acceleration data during natural walking (NW) at different ages, MSE decreased from childhood to adulthood, apparently contradicting the premises. On the contrary, authors hypothesised that this decrease was dependent on the specific task analysed and resulted from the concurrent increase in gait automaticity.This work aims to test this hypothesis, applying MSE on a non-paradigmatic task (tandem walking, TW), in order to exclude aspects related to automaticity.MSE was estimated on trunk acceleration data, collected on children, adolescents, and young adults during TW and NW. As hypothesized, MSE increased significantly with age in TW and decreased in NW on the sagittal plane. Assuming the development of complexity in TW as reference, MSE in NW showed a reduction to half of the complexity of TW with maturation on the sagittal plane. These results indicate MSE as sensitive to differences in performance due to maturation and to expected changes in complexity related to the specific performed task.

The Economic Impact of Space Weather: Where Do We Stand?

Space weather describes the way in which the Sun, and conditions in space more generally, impact human activity and technology both in space and on the ground. It is now well understood that space weather represents a significant threat to infrastructure resilience, and is a source of risk that is wide-ranging in its impact and the pathways by which this impact may occur. Although space weather is growing rapidly as a field, work rigorously assessing the overall economic cost of space weather appears to be in its infancy. Here, we provide an initial literature review to gather and assess the quality of any published assessments of space weather impacts and socioeconomic studies. Generally speaking, there is a good volume of scientific peer-reviewed literature detailing the likelihood and statistics of different types of space weather phenomena. These phenomena all typically exhibit "power-law" behavior in their severity. The literature on documented impacts is not as extensive, with many case studies, but few statistical studies. The literature on the economic impacts of space weather is rather sparse and not as well developed when compared to the other sections, most probably due to the somewhat limited data that are available from end-users. The major risk is attached to power distribution systems and there is disagreement as to the severity of the technological footprint. This strongly controls the economic impact. Consequently, urgent work is required to better quantify the risk of future space weather events.

Complexity of human gait pattern at different ages assessed using multiscale entropy: From development to decline.

Multiscale entropy (MSE) has been applied in biomechanics to evaluate gait stability during human gait and was found to be a promising method for evaluating fall risk in elderly and/or pathologic subjects. The hypothesis of this work is that gait complexity is a relevant parameter of gait development during life, decreasing from immature to mature gait and then increasing again during old age. In order to verify this hypothesis, MSE was applied on trunk acceleration data collected during gait of subjects of different ages: toddlers at the onset of walking, pre-scholar and scholar children, adolescents, young adults, adults and elderlies. MSE was estimated by calculating sample entropy (SEN) on raw unfiltered data of L5 acceleration along the three axes, using values of τ ranging from 1 to 6. In addition, other performance parameters (cadence, stride time variability and harmonic ratio) were evaluated. The results followed the hypothesized trend when MSE was applied on the vertical and/or anteroposterior axis of trunk acceleration: an age effect was found and adult SEN values were significantly different from children ones. From young adults to elderlies a slight increase in SEN values was shown although not statistically significant. While performance gait parameters showed adolescent gait similar to the one of adults, SEN highlighted that their gait maturation is not complete yet. In conclusion, present results suggest that the complexity of gait, evaluated on the sagittal plane, can be used as a characterizing parameter of the maturation of gait control.

Evaluation of toddler different strategies during the first six-months of independent walking: a longitudinal study.

Twenty infants (age 10-16 month) were analyzed using inertial sensors over a 6-month period after the onset of independent walking. Changes in gait temporal parameters, coordination and gait strategies were evaluated. Gait temporal parameters showed a developmental shift at 2 months of walking experience: after this period, a change in the developmental trend was present in most of the analyzed parameters. Cadence results showed that the increased velocity is more due to an increase in step length than to an increase in cadence, after the first two months of independent walking. Different gait strategies were identified during the first month of independent gait based on collected data; after one month, characteristics of the pendulum mechanism were present in each examined toddler.

Green synthesis of silver nanoparticles and their application to cotton fabrics.

Herein we present a green synthesis of silver nanoparticles (AgNPs) under the reducing action of sugar and the stabilizing action of polyethylene glycol (PEG). Factors affecting the synthesis notably molecular weight of PEG and concentrations of both sugar and silver nitrate were examined for the sake of optimization. Thus obtained AgNPs were characterized, by ultraviolet-visible (UV-vis) spectra for estimation of AgNPs formation and, Transmission electron microscopy (TEM) for determination of size and shape. AgNPs were applied with 1,2,3,4-butane tetracarboxylic acid (BTCA) and sodium hypophosphite (SHP) as a catalyst to cotton fabric. Application was performed according to the conventional pad-dry-cure technique. The treated fabrics were evaluated via monitoring morphological changes of the fibers using scanning electron microscopy (SEM), tensile strength and crease recovery angles in addition to bioassay of antimicrobial activity of the treated fabrics. Research output disclosed that PEG having molecular weight 2000 is the best among the other PEG used.

Gait variability and stability measures: minimum number of strides and within-session reliability.

BACKGROUND: Several methods are proposed in the literature for the quantification of gait variability/stability from trunk accelerations. Since outputs can be influenced by implementation differences, reliability assessment and standardization of implementation parameters are still an issue. The aim of this study is to assess the minimum number of required strides and the within-session reliability of 11 variability/stability measures. METHOD: Ten healthy participants walked in a straight line at self-selected speed wearing two synchronized tri-axial Inertial Measurement Units. Five variability measures were calculated based on stride times namely Standard deviation, Coefficient of variation, Inconsistency of variance, Nonstationary index and Poincaré plot. Six stability measures were calculated based on trunk accelerations namely Maximum Floquet multipliers, Short term/long term Lyapunov exponents, Recurrence quantification analysis, Multiscale entropy, Harmonic ratio and Index of harmonicity. The required minimum number of strides and the within-session reliability for each measure were obtained based on the interquartile range/mean ratio. Measures were classified in five categories (namely excellent, good, average, poor, and very poor) based on their reliability. RESULTS: The number of strides required to obtain a reliable measure was generally larger than those conventionally used. Variability measures showed average to poor reliability, while stability measures ranged from excellent to very poor reliability. CONCLUSION: Recurrence quantification analysis and multiscale entropy of trunk accelerations showed excellent reliability and a reasonable number of required strides. Based on these results, these measures should be taken into consideration in the assessment of fall risk.

New textiles of biocidal activity by introduce insecticide in cotton-poly (GMA) copolymer containing ß-Cd.

The present work deals with the preparation of innovative cotton textiles which act against blood sucking insects such as mosquitoes. Thus experiments were designed to incorporation of efficient insecticide (Permethrin, bioallethrin) in the macro-molecular structure of modified cotton fabrics. Chemical modification of cotton was realized by grafting with glycidyl methacrylate alone or in combination with ß-cyclodextrin by irradiation using fasting electron beam. Retreatment of the so obtained modified cotton was also made to increase the amount of CDs, and in turn, their cavities within the molecular structure of the modified cottons. Finished fabrics were though evaluated using chemical analysis; physical testing, bioassay tests and IR as well as SEM. Results obtained conclude that the amount of insecticide in the finished fabrics increases by increasing of the fixed amount of cyclodextrins which incorporate through their cavities the insecticide. The bioassay test shows that finished cotton fabrics display fast acting against mosquitoes.

Orbital stability analysis in biomechanics: a systematic review of a nonlinear technique to detect instability of motor tasks.

Falls represent a heavy economic and clinical burden on society. The identification of individual chronic characteristics associated with falling is of fundamental importance for the clinicians; in particular, the stability of daily motor tasks is one of the main factors that the clinicians look for during assessment procedures. Various methods for the assessment of stability in human movement are present in literature, and methods coming from stability analysis of nonlinear dynamic systems applied to biomechanics recently showed promise. One of these techniques is orbital stability analysis via Floquet multipliers. This method allows to measure orbital stability of periodic nonlinear dynamic systems and it seems a promising approach for the definition of a reliable motor stability index, taking into account for the whole task cycle dynamics. Despite the premises, its use in the assessment of fall risk has been deemed controversial. The aim of this systematic review was therefore to provide a critical evaluation of the literature on the topic of applications of orbital stability analysis in biomechanics, with particular focus to methodologic aspects. Four electronic databases have been searched for articles relative to the topic; 23 articles were selected for review. Quality of the studies present in literature has been assessed with a customised quality assessment tool. Overall quality of the literature in the field was found to be high. The most critical aspect was found to be the lack of uniformity in the implementation of the analysis to biomechanical time series, particularly in the choice of state space and number of cycles to include in the analysis.

Sensitivity analysis of an energetic muscle model applied at whole body level in recumbent pedalling.

Musculoskeletal models are used in order to describe and analyse the mechanics of human movement. In order to get a complete evaluation of the human movement, energetic muscle models were developed and were shown to be promising. The aim of this work is to determine the sensitivity of muscle mechanical and energetic model estimates to changes in parameters during recumbent pedalling. Inputs of the model were electromyography and joint angles, collected experimentally on one participant. The sensitivity analysis was performed on muscle-specific tension, physiological cross-sectional area, muscle maximal force, tendon rest length and percentage of fast-twitch fibres using an integrated sensitivity ratio. Soleus, gastrocnemius, vasti, gluteus and medial hamstrings were selected for the analyses. The energetic model was found to be always less sensitive to parameter changes than the mechanical model. Tendon slack length was found to be the most critical parameter for both energetic and mechanical models even if the effect on the energetic output was smaller than on muscle force and joint moments.

Serenoa repens (Permixon®) reduces intra- and postoperative complications of surgical treatments of benign prostatic hyperplasia.

AIM: The aim of this study was to evaluate the efficacy of pre-treatment with Serenoa repens (Permixon®) in reducing intra- and postoperative complications of surgical treatments of benign prostatic hyperplasia (BPH). METHODS: A total of 144 patients with BPH, who were candidates for transurethral resection of the prostate (TURP) and open prostatectomy (OP), were admitted to the study and randomized to receive either a daily pre-treatment with 320 mg of Serenoa repens, Permixon® for two months prior to surgery (G1) or to undergo surgery without any pre-treatment (G2). Preoperative and postoperative courses were carefully monitored for each patient. RESULTS: Of the 144 patients, 24 dropped out of the trial: 10 in G1 and 14 in G2. In G1, the duration of surgery was significantly shorter than in G2 (59.8 min vs. 77.6 min, respectively; P<0.001), no intraoperative complications were observed (0% vs. 15% in the control group; P=0.001) and transfusion needs were remarkably lower (0% in G1vs. 38.33% in G2; P<0.001). The postoperative course was significantly more favorable in G1 (with a shorter duration of catheterization, 64.95 h vs. 91.7 h in G2; P<0.001). There was also a significant change in hemodynamic parameters and the length of hospitalization was significantly shorter in the pretreated group (5.92 d in G1 vs. 7.92 d in G2; P<0.001). CONCLUSION: These data suggest that pre-treatment with Serenoa repens before surgery (TURP or OP) for BPH is effective in reducing intra- and postoperative complications.

Kinetic Bhatnagar-Gross-Krook model for fast reactive mixtures and its hydrodynamic limit.

A recently proposed consistent Bhatnagar-Gross-Krook-type approach for reversible bimolecular chemical reactions, well suited to deal with collision dominated gas mixtures in which mechanical and chemical relaxation times are of the same order of magnitude (fast reactions), is discussed. The model recovers essential features of the chemical process such as mass action law at equilibrium and reactive H theorem. The hydrodynamic limit, at both Euler and Navier-Stokes levels, is derived by a Chapman-Enskog procedure, in terms of the relevant hydrodynamic variables, and compared to the corresponding limits holding in the nonreactive and in the slowly reactive cases. In particular, results show that reactive corrections to transport coefficients cannot be neglected for fast reactions.

Lithiasis and risk factors.

Nephrolithiasis is a worldwide disease with high clinical and economic costs. The increasing incidence in industrialized countries seems to be related to several risk factors, which are partly inherited and partly acquired. Although risk factors in urolithiasis are still under discussion, their identification would provide a notable gain for the patient in terms of stone episodes, and for the health service in terms of costs. This article presents an easy classification of risk factors based on clinical background.

A physical phantom for the calibration of three-dimensional X-ray microtomography examination.

X-ray microtomography is rapidly gaining importance as a non-destructive investigation technique, especially in the three-dimensional examination of trabecular bone. Appropriate quantitative three-dimensional parameters describing the investigated structure were introduced, such as the model-independent thickness and the structure model index. The first parameter calculates a volume-based thickness of the structure in three dimensions independent of an assumed structure type. The second parameter estimates the characteristic form of which the structure is composed, i.e. whether it is more plate-like, rod-like or even sphere-like. These parameters are now experiencing a great diffusion and are rapidly growing in importance. To measure the accuracy of these three-dimensional parameters, a physical three-dimensional phantom containing different known geometries and thicknesses, resembling those of the examined structures, is needed. Unfortunately, such particular phantoms are not commonly available and neither does a consolidated standard exist. This work describes the realization of a calibration phantom for three-dimensional X-ray microtomography examination and reports an application example using an X-ray microtomography system. The calibration phantom (external size 13 mm diameter, 23 mm height) was based on various aluminium inserts embedded in a cylinder of polymethylmethacrylate. The inserts had known geometries (wires, foils, meshes and spheres) and thicknesses (ranging from 20 microm to 1 mm). The phantom was successfully applied to an X-ray microtomography device, providing imaging of the inserted structures and calculation of three-dimensional parameters such as the model-independent thickness and the structure model index. With the indications given in the present work it is possible to design a similar phantom in a histology laboratory and to adapt it to the requested applications.

Classic and common migraine suggestive clinical evidence of two separate entities.

To help clarify whether or not classic migraine (C1M) and common migraine (CoM) should be considered as a single entity, we compared the clinical features of a group of C1M patients with those of a group of CoM patients. Significant differences between the two forms of migraine were found in the following areas: age distribution of sufferers; family history of migraine, ischemic cerebrovascular disease, and coronary heart disease; age at onset; frequency of attacks; duration, location, and severity of pain; accompanying symptoms; and, evolution during weekends, menstruation, pregnancy, and puerperium. Our comparative investigation suggests that CIM and CoM are more distinct than previously considered.