1,734 research outputs found
Nanosized patterns as reference structures for macroscopic transport properties and vortex phases in YBCO films
This paper studies the striking correlation between nanosized structural
patterns in YBCO films and macroscopic transport current. A nanosized network
of parallel Josephson junctions laced by insulating dislocations is almost
mimicking the grain boundary structural network. It contributes to the
macroscopic properties and accounts for the strong intergranular pinning across
the film in the intermediate temperature range. The correlation between the two
networks enables to find out an outstanding scaling law in the (Jc,B) plane and
to determine meaningful parameters concerning the matching between the vortex
lattice and the intergranular defect lattice. Two asymptotic behaviors of the
pinning force below the flux flow regime are checked: the corresponding vortex
phases are clearly individuated.Comment: 4 pages, 4 figure
Validation of a score tool for measurement of histological severity in juvenile dermatomyositis and association with clinical severity of disease.
OBJECTIVES: To study muscle biopsy tissue from patients with juvenile dermatomyositis (JDM) in order to test the reliability of a score tool designed to quantify the severity of histological abnormalities when applied to biceps humeri in addition to quadriceps femoris. Additionally, to evaluate whether elements of the tool correlate with clinical measures of disease severity. METHODS: 55 patients with JDM with muscle biopsy tissue and clinical data available were included. Biopsy samples (33 quadriceps, 22 biceps) were prepared and stained using standardised protocols. A Latin square design was used by the International Juvenile Dermatomyositis Biopsy Consensus Group to score cases using our previously published score tool. Reliability was assessed by intraclass correlation coefficient (ICC) and scorer agreement (α) by assessing variation in scorers' ratings. Scores from the most reliable tool items correlated with clinical measures of disease activity at the time of biopsy. RESULTS: Inter- and intraobserver agreement was good or high for many tool items, including overall assessment of severity using a Visual Analogue Scale. The tool functioned equally well on biceps and quadriceps samples. A modified tool using the most reliable score items showed good correlation with measures of disease activity. CONCLUSIONS: The JDM biopsy score tool has high inter- and intraobserver agreement and can be used on both biceps and quadriceps muscle tissue. Importantly, the modified tool correlates well with clinical measures of disease activity. We propose that standardised assessment of muscle biopsy tissue should be considered in diagnostic investigation and clinical trials in JDM
THE EVOLUTION ACROSS AGES OF EFFICIENCY AND ECONOMY OF (ASSISTED) HUMAN LOCOMOTION AND EXERCISE
Human evolution and ingenuity both collaborated in providing biological/technological tools to move faster, despite of the same actuator, and to better adapt our locomotion to very different environments. While evolution resulted in a versatile musculo-skeletal system featuring optimization and energy-saving mechanisms to produce force and work more effectively, humans also invented passive tools, particularly in the last 4-5 millennia, allowing to moving faster and more economically on land, on/under water and in the air. Among the most featured examples: bone skating on ice, ancient cross-country skiing, bicycling, rowing. But also hand-held masses (Minetti & Ardigo, 2002) enhanced standing long jump and bows/crossbows made us throwing objects at longer distances (a hand-thrown arrow barely reach 25 m, while with a modern bow the distance exceeds 1.3 km). In the past few years we reviewed the historic evolution of passive tools devoted to enhance human locomotion (Minetti, 2004; Ardigo et al., 2005). Sometimes we built replicas of ancient tools (as in cycling - Minetti et al., 2001, cross-country skiing - Formenti et al., 2005 and ice skating - Formenti & Minetti, 2006), in other cases we used modern tools (as fins - Zamparo et al., 2002) in order to study, through biomechanical and metabolic experiments, the progressive adaptation of (the same) muscle to the different machines and environments. The focus of my presentation will be on how limitations of the musculo-skeletal system have been attenuated both inside (gear ratio, tendons) and outside (crank, gears, poles, skis, fins) the body. The relevance into the necessary mechanical work, the economy of transport and the related efficiency of motion/locomotion will be discussed
A new apparatus for deep patterning of beam sensitive targets by means of high-energy ion beam
The paper reports on a high precision equipment designed to modify over
3-dimensions (3D) by means of high-energy gold ions the local properties of
thin and thick films. A target-moving system aimed at creating patterns across
the volume is driven by an x-y writing protocol that allows one to modify beam
sensitive samples over micrometer-size regions of whatever shape. The apparatus
has a mechanical resolution of 15 nm. The issue of the local fluence
measurement has been particularly addressed. The setup has been checked by
means of different geometries patterned on beam sensitive sheets as well as on
superconducting materials. In the last case the 3D modification consists of
amorphous nanostructures. The nanostructures create zones with different
dissipative properties with respect to the virgin regions. The main analysis
method consists of magneto-optical imaging that provides local information on
the electrodynamics of the modified zones. Features typical of non-linear
current flow hint at which pattern geometry is more functional to applications
in the framework of nanostructures across superconducting films.Comment: 7 page
Health-related quality of life and functional changes in DMD:A 12-month longitudinal cohort study
Family caregivers of people with amyotrophic lateral sclerosis (ALS) live stressful lives in which they spend most of their time caring for their loved ones and managing difficult situations, thereby reducing the time spent in taking care of themselves. This situation may last several years. Previous literature has widely highlighted that this situation reduces caregivers' quality of life and increases their psychological distress and risk of health problems, but there is a lack of studies that focus on psychological interventions for these situations. This qualitative study examined a pilot experience of two mutual support groups for family caregivers of people with ALS. The aim was to identify caregivers' needs, the prominent aspects of their experience, and to understand whether and how this intervention strategy might help them. Six partners (four men and two women) and six adult children (five women and one man) participated in the groups, which were conducted in northern Italy. After the support groups finished, participants underwent semi-structured interviews. The authors conducted a content analysis of the transcripts of the interviews and the 20 group sessions. The thematic areas identified were "caregiving," "being the son/daughter of a person with ALS," "being the partner of a person with ALS," "group experience" and "group evaluation." The caregiving experience was profoundly different depending on whether the caregiver was a son/daughter or a partner of a patient with ALS. Moreover, comparison with peers and mutual support helped participants to better cope with ALS and its consequences, to improve their care for their relatives and to overcome typical caregiver isolation. These results suggest the usefulness of involving communities in caregiver support in order to create new networks and activate personal and social resources for well-being
Eculizumab treatment of atypical haemolytic uraemic syndrome: results from the largest prospective clinical trial to date
Inertial biometry from commercial 3D body meshes
Body segments inertial parameters (or, more generally encompassing humans and animal species, inertial biometry), often necessary in kinetics calculations, have been obtained in the past from cadavers, medical 3D imaging, 3D scanning, or geometric approximations. This restricted the inertial archives to a few species. The methodology presented here uses commercial 3D meshes of human and animal bodies, which can be further re-shaped and 'posed', according to an underlying skeletal structure, before processing. The sequence of steps from virtually chopping the mesh to the estimation of inertial parameters of body segments is described. The accuracy of the method is tested by comparing the estimated results to real data published for humans (male and female), horses, and domestic cats. The proposed procedure opens the possibility of remarkably expanding biomechanics research when body size and shape change, or when external tools, such as prosthesis and sport material, take part in biological movement
Autologous deciduous tooth-derived material for alveolar ridge preservation: a clinical and histological case report
The management of the alveolar socket is fundamental to create conditions that would allow the positioning of dental implants in the same site, when required. A number of biomaterials were described in scientific literature to be used for alveolar socket preservation immediately after tooth extraction: autogenous grafts, allograft (of various origin), and synthetic products. Among the autogenous biomaterials, some authors proposed the use of autogenous dentin and/or enamel, retrieved from teeth, adequately managed, and purified. The present case report with two-year follow-up shows one case of alveolar socket preservation by using tooth graft material that was subsequently treated with one implant-supported rehabilitation in the same site. The paper presents clinical and histological outcomes and confirms the feasibility of adopting such autogenous biomaterial in standard procedures
Measurements of the reaction of antiproton annihilation at rest at three hydrogen target densities
The proton-antiproton annihilation at rest into the final state
was measured for three different target densities: liquid hydrogen, gaseous
hydrogen at NTP and at a low pressure of 5 mbar. The yield of this reaction in
the liquid hydrogen target is smaller than in the low-pressure gas target. The
branching ratios of the channel were calculated on the basis of
simultaneous analysis of the three data samples. The branching ratio for
annihilation into from the protonium state turns out to be
about ten times smaller as compared to the one from the state.Comment: 10 pages, 3 Postscript figures. Accepted by Physics Letters
Metabolic cost and mechanical work of walking in a virtual reality emulator
Purpose: The purpose of this study was to investigate the metabolic cost (C), mechanical work, and kinematics of walking on a multidirectional treadmill designed for locomotion in virtual reality. Methods: Ten participants (5 females, body mass 67.2 ± 8.1 kg, height 1.71 ± 0.07 m, age 23.6 ± 1.9 years, mean ± SD) walked on a Virtuix Omni multidirectional treadmill at four imposed stride frequencies: 0.70, 0.85, 1.00, and 1.15 Hz. A portable metabolic system measured oxygen uptake, enabling calculation of C and the metabolic equivalent of task (MET). Gait kinematics and external, internal, and total mechanical work (WTOT) were calculated by an optoelectronic system. Efficiency was calculated either as WTOT/C or by summing WTOT to the work against sliding frictions. Results were compared with normal walking, running, and skipping. Results: C was higher for walking on the multidirectional treadmill than for normal walking, running, and skipping, and decreased with speed (best-fit equation: C = 20.2–27.5·speed + 15.8·speed2); the average MET was 4.6 ± 1.4. Mechanical work was higher at lower speeds, but similar to that of normal walking at higher speeds, with lower pendular energy recovery and efficiency; differences in efficiency were explained by the additional work against sliding frictions. At paired speeds, participants showed a more forward-leaned trunk and higher ankle dorsiflexion, stride frequency, and duty factor than normal walking. Conclusion: Walking on a multidirectional treadmill requires a higher metabolic cost and different mechanical work and kinematics than normal walking. This raises questions on its use for gait rehabilitation but highlights its potential for high-intensity exercise and physical activity promotion
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