Did Going North Give Us Migraine? An Evolutionary Approach on Understanding Latitudinal Differences in Migraine Epidemiology

This commentary discusses a recent publication by evolutionary biologists with strong implications for migraine experts. The Authors showed that a gene polymorphism associated with migraine gave our ancestors an evolutionary advantage when colonizing northern, and thus colder, territories. They then highlight that the prevalence of migraine may differ among countries because of climatic adaptation. These results may prove useful in planning both epidemiological and physiological studies in the field of migraine

Coupled DEM-LBM method for the free-surface simulation of heterogeneous suspensions

The complexity of the interactions between the constituent granular and liquid phases of a suspension requires an adequate treatment of the constituents themselves. A promising way for numerical simulations of such systems is given by hybrid computational frameworks. This is naturally done, when the Lagrangian description of particle dynamics of the granular phase finds a correspondence in the fluid description. In this work we employ extensions of the Lattice-Boltzmann Method for non-Newtonian rheology, free surfaces, and moving boundaries. The models allows for a full coupling of the phases, but in a simplified way. An experimental validation is given by an example of gravity driven flow of a particle suspension

A DEM evaluation of the clogging probability of debris-flow barriers: from the contact parameters to the overall interaction mechanism

In this work, we study the interaction between geophysical phenomena such as debris ow, and retention structures. We propose a numerical tool based on the Discrete Element Method, where the frictional nature of natural grains is reproduced through the implementation of frictional contacts and rolling resistance. The relationship between the contact parameters and the overall behavior of the granular mass is investigated through a set of heap-formation calibration tests, which allow to track the transition from a fluid regime to stable granular structures. The information gathered in the calibration tests is then used to study the stoppage of a granular flow on an incline. This is induced by placing a slit dam with a single vertical opening. The relative size between slit opening and grain diameter determines the overall e ciency of the retention, but also the basal friction controlled by the channel inclination plays a vital role. Numerous threshold are in this way obtained. The grains clog instantly for small relative opening sizes, and flow freely when a very large slit is used. Two secondary thresholds exist in the intermediate range, corresponding to a partial release of the mass through multiple consecutive clogging and ruptures of the grains behind the slit, and to the delayed formation of a single two-dimensional arch at the base. The consequences for the design of structures of this type are then discussed

Physical activity programs for balance and fall prevention in elderly: A systematic review

BACKGROUND: Due to demographic changes the world's population is progressively ageing. The physiological decay of the elderly adult may lead to a reduction in the ability to balance and an increased risk of falls becoming an important issue among the elderly. In order to counteract the decay in the ability to balance, physical activity has been proven to be effective. The aim of this study is to systematically review the scientific literature in order to identify physical activity programs able to increase balance in the elderly. METHODS: This review is based on the data from Medline-NLM, Pubmed, ScienceDirect, and SPORTDiscuss and includes randomized control trials that have analyzed balance and physical activity in healthy elderly over 65 years of age during the last decade. A final number of 8 manuscripts were included in the qualitative synthesis, which comprised 200 elderly with a mean age of 75.1 ± 4.4 years. The sample size of the studies varied from 9 to 61 and the intervention periods from 8 to 32 weeks. RESULTS: Eight articles were considered eligible and included in the quantitative synthesis. The articles investigated the effects of resistance and aerobic exercise, balance training, T-bow© and wobble board training, aerobic step and stability ball training, adapted physical activity and Wii Fit training on balance outcomes. Balance measures of the studies showed improvements between 16% and 42% compared to baseline assessments. CONCLUSIONS: Balance is a multifactorial quality that can be effectively increased by different exercise training means. It is fundamental to promote physical activity in the aging adult, being that a negative effect on balance performance has been seen in the no-intervention control groups

Debris-flow interaction with slid barriers: efficiency and clogging mechanism

The design of structures for debris flow mitigation is still mostly based on the application of simple, empirical formulas. Standard practice suggests that slit structures might be a convenient solution for partially stopping the flow by filtering out the largest grains, which represent the most hazardous component. However, efforts towards the development of rational approaches for the design of the abovementioned structures have been hindered by the complexity of the debris materials. The interaction between a granular flow composed of monodisperse grains and a slit barrier is in this work reproduced by a discrete numerical model. The model is validated by comparison with a set of experimental runs with an analogous geometry. While the model greatly simplifies reality, it is anyway able to give insight in how clogging, and eventually stoppage, develops. Traditionally, the slit size is prescribed by choosing a multiple of the desired grain size to be stopped. The results highlight how stoppage can be achieved with a relatively wide range of possible slit openings. A family of recurring behaviors is observed, depending on the amount of entrained material and on whether stoppage is instantaneous or delayed. Finally, the initial assumptions are relaxed by moving to a bi-disperse flow. The results of the monodisperse case can be generalized to the bi-disperse case by definition of an equivalent radius

Comparison of depth-averaged and full-3D model for the benchmarking exercise on landslide runout

Two models, with fundamental differences in their approaches, are used for modeling benchmarking exercise. The first, RASH3D, is based on a set of depth-averaged equation, solved in an Eulerian framework. The second, HYBIRD, employs a 3D Lattice-Boltzmann Model (LBM), i.e. the conservation equations are not depth-averaged and therefore multiple velocity measures are available over the depth. The model output are compared for what concerns the Yu-Tung debris flow back-analysis. Two additional cases are then analyzed using RASH3D

Multiple-Sliding-Surface Guidance and Control for Terminal Atmospheric Reentry and Precise Landing

The development of an effective guidance and attitude control architecture for terminal descent and landing represents a crucial issue for the design of reusable vehicles capable of performing a safe atmospheric planetary entry. The sliding mode control represents a nonlinear technique able to generate an effective real-time closed-loop guidance law, even in the presence of challenging contingencies. This work proposes a multiple sliding-surface guidance control law that is able to drive a lifting vehicle toward safe landing conditions, associated with a desired downrange, crossrange, runway heading, and final vertical velocity at touchdown, even starting from challenging initial conditions. The time derivatives of the lift coefficient and the bank angle are used as the control inputs, whereas the sliding surfaces are defined so that these two inputs are involved simultaneously in the lateral and the vertical guidance. The commanded attitude is pursued by the attitude control system, which employs a feedback nonlinear control law that enjoys quasi-global stability properties. Effectiveness and accuracy of the guidance and control strategy at hand are proven numerically by means of a Monte Carlo campaign, in the presence of stochastic wind and large dispersions on the initial conditions

From depth-averaging to fully three-dimensional modelling of debris-flow dynamics

Two numerical codes, with fundamental differences in their approaches, are used for modeling the Yu Tung debris flow, which occurred in Hong Kong in 2008. The first code, RASH3D, is based depthaveraged St. Venant equations, solved in an Eulerian framework. The second code, HYBIRD, is fully 3D and based on Lattice-Boltzmann Model (LBM), i.e. the conservation equations are not depth-averaged and therefore multiple velocity measures are available over the depth. The two model output are compared and discussed

The challenge of perioperative pain management in opioid-tolerant patients

The increasing number of opioid users among chronic pain patients, and opioid abusers among the general population, makes perioperative pain management challenging for health care professionals. Anesthesiologists, surgeons, and nurses should be familiar with some pharmacological phenomena which are typical of opioid users and abusers, such as tolerance, physical dependence, hyperalgesia, and addiction. Inadequate pain management is very common in these patients, due to common prejudices and fears. The target of preoperative evaluation is to identify comorbidities and risk factors and recognize signs and symptoms of opioid abuse and opioid withdrawal. Clinicians are encouraged to plan perioperative pain medications and to refer these patients to psychiatrists and addiction specialists for their evaluation. The aim of this review was to give practical suggestions for perioperative management of surgical opioid-tolerant patients, together with schemes of opioid conversion for chronic pain patients assuming oral or transdermal opioids, and patients under maintenance programs with methadone, buprenorphine, or naltrexone