641 research outputs found
Multilevel upper body movement control during gait in children with cerebral palsy
Upper body movements during walking provide information about balance control and gait stability. Typically developing (TD) children normally present a progressive decrease of accelerations from the pelvis to the head, whereas children with cerebral palsy (CP) exhibit a general increase of upper body accelerations. However, the literature describing how they are transmitted from the pelvis to the head is lacking. This study proposes a multilevel motion sensor approach to characterize upper body accelerations and how they propagate from pelvis to head in children with CP, comparing with their TD peers. Two age-and gender-matched groups of 20 children performed a 10m walking test at self-selected speed while wearing three magneto-inertial sensors located at pelvis, sternum, and head levels. The root mean square value of the accelerations at each level was computed in a local anatomical frame and its variation from lower to upper levels was described using attenuation coefficients. Between-group differences were assessed performing an ANCOVA, while the mutual dependence between acceleration components and the relationship between biomechanical parameters and typical clinical scores were investigated using Regression Analysis and Spearman's Correlation, respectively (alpha = 0.05). New insights were obtained on how the CP group managed the transmission of accelerations through the upper body. Despite a significant reduction of the acceleration from pelvis to sternum, children with CP do not compensate for large accelerations, which are greater than in TD children. Furthermore, those with CP showed negative sternum-to-head attenuations, in agreement with the documented rigidity of the head-trunk system observed in this population. In addition, the estimated parameters proved to correlate with the scores used in daily clinical practice. The proposed multilevel approach was fruitful in highlighting CP-TD gait differences, supported the in-field quantitative gait assessment in children with CP and might prove beneficial to designing innovative intervention protocols based on pelvis stabilization
Thermal and Cold Neutron Computed Tomography at the Los Alamos Neutron Scattering Center Using an Amorphous Silicon Detector Array
The use of the EG&G-Heimann RTM 128 [1] or dpiX FS20 [2] amorphous silicon (a-Si) detector array for thermal neutron radiography/computed tomography has proven to be a quick and efficient means of producing high quality digital radiographic images. The resolution, although not as good as film, is about 750 μm with the RTM and 127 μm with the dpiX array with a dynamic range in excess of 2800. In many respects using an amorphous silicon detector is an improvement over other techniques such as imaging with a CCD camera, using a storage phosphor plate or film radiography. Unlike a CCD camera, which is highly susceptible to radiation damage, a-Si detectors can be placed in the beam directly behind the object under examination and do not require any special optics or turning mirrors. The amorphous silicon detector also allows enough data to be acquired to construct a digital image in just a few seconds (minimum gate time 40 ms) whereas film or storage plate exposures can take many minutes and need to be digitized with a scanner. The flat panel can, therefore, acquire a complete 3D computed tomography data set in just a few tens of minutes. While a-Si detectors have been proposed for use in imaging neutron beams [3], this is the first reported implementation of such a detector for neutron imaging [4]
Usefulness of magnetoinertial wearable devices in neurorehabilitation of children with cerebral palsy
Background. Despite the increasing use of wearable magnetoinertial measurement units (MIMUs) for gait analysis, the efficacy of MIMU-based assessment for planning rehabilitation has not been adequately documented yet. Methods. The usefulness of a MIMU-based assessment was evaluated comparing the data acquired by three MIMUs located at the pelvis, sternum, and head levels in 12 children with cerebral palsy (CP, age: 2-9 years) and 12 age-matched children with typical development (TD). Gait stability was quantified in terms of acceleration attenuation coefficients from pelvis to head, pelvis to sternum, and sternum to head. Children with CP were randomly divided in two groups: in the first group (CPI), MIMU-based parameters were used by therapists for planning patient-tailored rehabilitation programs, whereas in the second group (CPB), therapists were blind to the MIMU-based assessment results. Both CPI and CPB were tested before and after the relevant neurorehabilitation program. Ad hoc questionnaires were also administered to therapists of the CPI group to assess the degree of usefulness perceived about the information provided by the MIMU-based assessment. Results. Significant differences were found between children with CP and those with TD for the acceleration attenuation coefficient from pelvis to head (p = 0 048) and from pelvis to sternum (p = 0 021). After neurorehabilitation, this last parameter increased more in CPI (35%) than in CPB (6%, p = 0 017 for the interaction group per time). The results of the questionnaires showed that therapists agreed with the usability (100% judged it as "easy to use") and usefulness of the MIMU-based assessment in defining patient-oriented interventions (87%). Conclusions. There is a large debate in literature about the efficacy of classical gait analysis that should be enlarged to new technological approaches, such as that based on MIMUs. This study is a first proof of concept about the efficacy of this approach for neurorehabilitation of children with CP
Automotive leathers – evaluating the performance limits (part II)
Content:
Consumers perceive leather as a durable and natural product. To support this positive image, car manufacturers have set demanding performance profiles addressing wear, emissions and sustainable
manufacture. Poor performance of auto leather becomes visible as the polymeric finishing coat wears off or cracks over time. Therefore ageing property is seen as a representative key performance parameter and is determined by checking how flexible and strong a polymer coating remains after leather has been exposed to light, heat and humidity for a given time. Ageing of leather is complex to determine and depends on various parameters and requires a full system approach .
In a first step different type of crusts (wet-blue, wet-white) were prepared and finished with a standard polyurethane coating. It turned out that the selection of the right fat liquors and tanning agents as well as the presence of vegetable tannins play an important role. On top of this the effective use of proper protective chemicals like anti-oxidants is needed.
In a second approach the polymer coating itself was studied and optimized with regard to aged flexing and abrasion. Parameters like polymer type, crosslinking, application technology, coating thickness and impact of additives were investigated and tested when applied on the best crust leathers selected from part 1 of this work. Results show that not only is the right selection of polymers critical but also so is the way the coat is being applied . Furthermore coating thickness greatly defines wear (abrasion), lightfastness and ageing properties. Additives like dulling agents, levelers, feel agents, waxes ,fillers although needed can weaken the integrity of the polymer matrix and consequently reduce physical and chemical fastness properties. This may also apply to a certain extent to protective additives such as anti-oxidants and UV stabilizers, but when used properly their advantages outweigh the potential disadvantages. As to application, special emphasis is given to transfer coating technology which can provide advantages in application and quality consistency but also with regards to fastness properties such as wear and ageing.
Take-Away:
- crust leather has a critical impact on performance of finishing coat of automotive leathers and requires careful selction of products and use of protective chemical
- polymer selection and use of protective chemical play an important role for achieving good aged flexing performance
- type of application of finishing coat on auto leather further determines the performance of coatin
LCA assessment related to the evolution of the earthquake performance of a strategic structure
Several buildings and infrastructures, located in urban areas, are identified as strategic in the case of an earthquake event. This is the case of a water treatment plant which is currently built in Genoa, Italy, and which has been assessed for the scope of this research. Since the structure has been designed following the seismic design prescriptions, this work aims to provide a preliminary assessment of how the degradation mechanisms do affect its earthquake response. To this purpose, both chloride attack and carbonation are taken into account as main degradation mechanisms. Moreover, due to the importance of the water treatment plant, to develop a realistic Life Cycle Assessment (LCA) analysis, the earthquake resistance of the structure and its evolution over time as a function of the aforesaid degradation mechanisms, have been accounted as Serviceability Limit State to estimate the frequency of the maintenance activities needed in a timeframe of 100 years
One-Stage Coverage of Leg Region Defects with STSG Combined with VAC Dressing Improves Early Patient Mobilisation and Graft Take: A Comparative Study
Lower limb skin defects are very common and can result from a wide range of aetiologies. Split thickness skin graft (STSG) is a widely used method to address these problems. The role of postoperative dressing is primary as it permits one to apply a uniform pressure over the grafted area and promote adherence. Focusing on lower limb reconstruction, our clinical study compares the application of V.A.C. (Vacuum Assisted Closure) Therapy vs. conventional dressing in the immediate postoperative period following skin grafting. We included in the study all patients who received skin grafts on the leg region between January 2015 and December 2018, despite the aetiology of the defect. Only reconstructions with complete preoperative and postoperative follow-up data were included in the study. Patients were divided into two groups depending on if they received a traditional compressive dressing or a VAC dressing in the immediate postoperative period. We could retain 92 patients, 23 in the No VAC group and 69 in the VAC group. The patients included in the VAC group showed a statistically significant higher rate of graft take together with a lower immobilisation time (p < 0.05). Moreover, a lower rate of postoperative infection was recorded in the VAC group. This study represents the largest in the literature to report in detail surgical outcomes comparing the use of VAC therapy vs. conventional dressing after STSG in the postoperative management of lower limb reconstruction using skin grafts. VAC therapy was used to secure the grafts in the leg region, increasing the early graft take rate while at the same time improving patient mobilisation
Characterization of atmospheric aerosol optical properties based on the combined use of a ground-based Raman lidar and an airborne optical particle counter in the framework of the Hydrological Cycle in the Mediterranean Experiment – Special Observation Period 1
Vertical profiles of the particle backscattering coefficient
at 355, 532 and 1064 nm measured by the University of Basilicata Raman
lidar system (BASIL) have been compared with simulated particle backscatter profiles obtained through a Mie
scattering code based on the use of simultaneous and almost co-located
profiles provided by an airborne optical particle counter. Measurements
were carried out during dedicated flights of the French research aircraft
ATR42 in the framework of the European Facility for Airborne Research (EUFAR)
project “WaLiTemp”, as part of the Hydrological Cycle in the Mediterranean
Experiment – Special Observation Period 1 (HyMeX-SOP1). Results from two
selected case studies are reported and discussed in the paper, and a dedicated analysis approach is illustrated and applied to the
dataset. Results reveal a good agreement between measured and simulated
multi-wavelength particle backscattering profiles. Specifically, simulated
and measured particle backscattering profiles at 355 and 532 nm for the second case study are found to
deviate less than 15 % (mean value =5.9 %) and 50 % (mean
value =25.9 %), respectively, when considering the presence of a
continental–urban aerosol component, while slightly larger deviation values are found for the first study. The reported good agreement between
measured and simulated multi-wavelength particle backscatter profiles
testifies to the ability of multi-wavelength Raman lidar systems to infer
aerosol types at different altitudes.</p
Nuclear de-excitation line spectrum of Cassiopeia A
The supernova remnant Cassiopeia A is a prime candidate for accelerating
cosmic ray protons and ions. Gamma rays have been observed at GeV and TeV
energies, which indicates hadronic interactions, but they could also be caused
by inverse-Compton scattering of low-energy photons by accelerated electrons.
We seek to predict the flux of nuclear de-excitation lines from Cas A through
lower-energy cosmic rays and to compare it with COMPTEL measurements. Assuming
a hadronic origin of the high-energy emission, we extrapolate the cosmic ray
spectrum down to energies of 10 MeV, taking into account an equilibrium
power-law momentum spectrum with a constant slope. We then calculate the
nuclear line spectrum of Cassiopeia A, considering the most prominent chemical
elements in the MeV band and their abundances as determined by X-ray
spectroscopy. We show that the predicted line spectrum is close to the level of
the COMPTEL sensitivity and agrees with conservative upper limits.Comment: 4 pages, 1 figure, accepted for publication by A&
Biomarker phenotyping drives clinical management in axillary sentinel node: A retrospective study on women with primary breast cancer in 2002
The current study examined if cancer biomarker phenotyping could predict the clinical/pathological status of axillary nodes in women with primary breast cancer. Primary breast cancers from 2002 were analyzed for tumor size, estrogen receptor (ER), progesterone receptor (PgR), Ki.67MIB expression and Her2/neu amplification. Relationships between the clinical and pathological status of the axilla and the biological subtypes classification were analyzed using univariate, multivariate and regression tree analysis. A total of 65% of women with axillary nodes clinically involved had complete axillary node dissection (ALND) while 705 women with clinically negative axillary underwent sentinel lymph node biopsy (SLNB), 18.5% of the latter had at least one pathologically SLNB involved node. Multivariate analysis revealed that the Luminal A subtype was significantly associated (OR 0.62; P<10-9) with clinical negative axilla while HER2pos/not Luminal was associated with clinical positivity (OR 1.71; P<0.01). No significant association between biological subtypes and SLNB status was demonstrated. Regression tree analysis revealed that subgroups with significantly different probability of SLNB status were separated according to tumor size and PgR values. In conclusion, the current study demonstrated that biomarker breast cancer phenotyping is significantly associated with clinical status of axillary nodes but not with pathological involvement of nodes at SLNB. Regression tree analysis could represent a valid attempt to individualize some patients subgroups candidate to different surgical axilla approaches
5.9-keV Mn K-shell X-ray luminosity from the decay of Fe-55 in Type Ia supernova models
We show that the X-ray line flux of the Mn Kα line at 5.9 keV from the decay of 55Fe is
a promising diagnostic to distinguish between Type Ia supernova (SN Ia) explosion models.
Using radiation transport calculations, we compute the line flux for two three-dimensional
explosion models: a near-Chandrasekhar mass delayed detonation and a violent merger of
two (1.1 and 0.9 M⊙) white dwarfs. Both models are based on solar metallicity zero-age
main-sequence progenitors. Due to explosive nuclear burning at higher density, the delayeddetonation
model synthesizes ∼3.5 times more radioactive 55Fe than the merger model. As
a result, we find that the peak Mn Kα line flux of the delayed-detonation model exceeds
that of the merger model by a factor of ∼4.5. Since in both models the 5.9-keV X-ray flux
peaks five to six years after the explosion, a single measurement of the X-ray line emission
at this time can place a constraint on the explosion physics that is complementary to those
derived from earlier phase optical spectra or light curves. We perform detector simulations
of current and future X-ray telescopes to investigate the possibilities of detecting the X-ray
line at 5.9 keV. Of the currently existing telescopes, XMM–Newton/pn is the best instrument
for close (!1–2 Mpc), non-background limited SNe Ia because of its large effective area. Due
to its low instrumental background, Chandra/ACIS is currently the best choice for SNe Ia
at distances above ∼2 Mpc. For the delayed-detonation scenario, a line detection is feasible
with Chandra up to ∼3 Mpc for an exposure time of 106 s. We find that it should be possible
with currently existing X-ray instruments (with exposure times !5 × 105 s) to detect both
of our models at sufficiently high S/N to distinguish between them for hypothetical events
within the Local Group. The prospects for detection will be better with future missions. For
example, the proposed Athena/X-IFU instrument could detect our delayed-detonation model
out to a distance of ∼5 Mpc. This would make it possible to study future events occurring
during its operational life at distances comparable to those of the recent supernovae SN 2011fe
(∼6.4 Mpc) and SN 2014J (∼3.5 Mpc)
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