2,691 research outputs found
3-D Hand Pose Estimation from Kinect's Point Cloud Using Appearance Matching
We present a novel appearance-based approach for pose estimation of a human
hand using the point clouds provided by the low-cost Microsoft Kinect sensor.
Both the free-hand case, in which the hand is isolated from the surrounding
environment, and the hand-object case, in which the different types of
interactions are classified, have been considered. The hand-object case is
clearly the most challenging task having to deal with multiple tracks. The
approach proposed here belongs to the class of partial pose estimation where
the estimated pose in a frame is used for the initialization of the next one.
The pose estimation is obtained by applying a modified version of the Iterative
Closest Point (ICP) algorithm to synthetic models to obtain the rigid
transformation that aligns each model with respect to the input data. The
proposed framework uses a "pure" point cloud as provided by the Kinect sensor
without any other information such as RGB values or normal vector components.
For this reason, the proposed method can also be applied to data obtained from
other types of depth sensor, or RGB-D camera
Magma and fluid migration at Yellowstone Caldera in the last three decades inferred from InSAR, leveling and gravity measurements
We studied the Yellowstone caldera geological unrest between 1977 and 2010 by investigating
temporal changes in differential Interferometric Synthetic Aperture Radar (InSAR), precise spirit leveling and
gravity measurements. The analysis of the 1992–2010 displacement time series, retrieved by applying the SBAS
InSAR technique, allowed the identification of three areas of deformation: (i) the Mallard Lake (ML) and Sour
Creek (SC) resurgent domes, (ii) a region close to the Northern Caldera Rim (NCR), and (iii) the eastern Snake
River Plain (SRP). While the eastern SRP shows a signal related to tectonic deformation, the other two regions
are influenced by the caldera unrest. We removed the tectonic signal from the InSAR displacements, and we
modeled the InSAR, leveling, and gravity measurements to retrieve the best fitting source parameters. Our
findings confirmed the existence of different distinct sources, beneath the brittle-ductile transition zone, which
have been intermittently active during the last three decades. Moreover, we interpreted our results in the light
of existing seismic tomography studies. Concerning the SC dome, we highlighted the role of hydrothermal
fluids as the driving force behind the 1977–1983 uplift; since 1983–1993 the deformation source transformed
into a deeper one with a higher magmatic component. Furthermore, our results support the magmatic nature
of the deformation source beneath ML dome for the overall investigated period. Finally, the uplift at NCR is
interpreted as magma accumulation, while its subsidence could either be the result of fluids migration outside
the caldera or the gravitational adjustment of the source from a spherical to a sill-like geometr
Differential sensitivity of brainstem vs cortical astrocytes to changes in pH reveals functional regional specialization of astroglia
Astrocytes might function as brain interoceptors capable of detecting different (chemo)sensory modalities and transmitting sensory information to the relevant neural networks controlling vital functions. For example, astrocytes which reside near the ventral surface of the brainstem (central respiratory chemosensitive area) respond to physiological decreases in pH with vigorous elevations in intracellular Ca(2+) and release of ATP. ATP transmits astroglial excitation to the brainstem respiratory network and contributes to adaptive changes in lung ventilation. Here we show that in terms of pH-sensitivity ventral brainstem astrocytes are clearly distinct from astrocytes residing in the cerebral cortex. We monitored vesicular fusion in cultured rat brainstem astrocytes using total internal reflection fluorescence microscopy and found that approximately 35% of them respond to acidification with an increased rate of exocytosis of ATP-containing vesicular compartments. These fusion events require intracellular Ca(2+) signaling and are independent of autocrine ATP actions. In contrast, the rate of vesicular fusion in cultured cortical astrocytes is not affected by changes in pH. Compared to cortical astrocytes, ventral brainstem astrocytes display higher levels of expression of genes encoding proteins associated with ATP vesicular transport and fusion, including vesicle-associated membrane protein-3 and vesicular nucleotide transporter. These results suggest that astrocytes residing in different parts of the rat brain are functionally specialized. In contrast to cortical astrocytes, astrocytes of the brainstem chemosensitive area(s) possess signaling properties which are functionally relevant – they are able to sense changes in pH and respond to acidification with enhanced vesicular release of ATP
On the Effects of Core Microstructure on Energy Absorbing Capabilities of Sandwich Panels Intended for Additive Manufacturing
Increasing transportation safety can be observed as one of the biggest engineering chal-lenges. This challenge often needs to be combined with the need to deliver engineering solutions that are able to lower the environmental impact of transportation, by reducing fuel consumption. Consequentially, these topics have attracted considerable research efforts. The present work aims to address the previously cited challenges by maximizing the energy absorption capabilities of hybrid aluminum/composite shock absorbers with minimal thickness and mass. This engineering solution makes it possible to lighten vehicles and reduce fuel consumption, without compromising safety, in terms of crashworthiness capabilities. A numerical sensitivity study is presented, where the absorbed energy/mass (AE/m) and the absorbed energy/total panel thickness (AE/Htot) ratios, as a consequence of low-velocity impact simulations performed on six different shock absorbers, are compared. These hybrid shock absorbers have been numerically designed by modifying the core thickness of two basic absorbers’ configurations, characterized, respectively, by a metallic lattice core, intended to be produced through additive manufacturing, and a standard metallic honeycomb core. This work provides interesting information for the development of shock absorbers, which should be further developed with an experimental approach. Indeed, it demonstrates that, by inte-grating composite skins with a very light core producible, by means of additive manufacturing ca-pabilities, it is possible to design shock absorbers with excellent performance, even for very thin configurations with 6 mm thickness, and to provide a significant increase in AE/m ratios when compared to the respective equal volume standard honeycomb core configurations. This difference between the AE/m ratios of configurations with different core designs increases with the growth in volume. In detail, for configurations with a total thickness of 6 mm, the AE/m increases in additive manufacturing configurations by approximately 93%; for those with a total thickness of 10 mm, the increase is 175%, and, finally, for those with a total thickness of 14 mm, the increase is 220%
Structural and catalytic insights into HoLaMa, a derivative of Klenow DNA polymerase lacking the proofreading domain
We report here on the stability and catalytic properties of the HoLaMa DNA polymerase, a Klenow sub-fragment lacking the 3\u2019-5\u2019 exonuclease domain. HoLaMa was overexpressed in Escherichia coli, and the enzyme was purified by means of standard chromatographic techniques. High-resolution NMR experiments revealed that HoLaMa is properly folded at pH 8.0 and 20C. In addition, urea induced a cooperative folding to unfolding transition of HoLaMa, possessing an overall thermodynamic stability and a transition midpoint featuring \u394G and C M equal to (15.7 \ub1 1.9) kJ/mol and (3.5 \ub1 0.6) M, respectively. When the catalytic performances of HoLaMa were compared to those featured by the Klenow enzyme, we did observe a 10-fold lower catalytic efficiency by the HoLaMa enzyme. Surprisingly, HoLaMa and Klenow DNA polymerases possess markedly different sensitivities in competitive inhibition assays performed to test the effect of single dNTPs
Resultados del efecto de dos niveles de densidad de siembra y fertilización sobre la producción de dos cultivares de alfalfa. Dos años de producción
La alfalfa (Medicago sativa) es uno de los principales cultivos forrajeros para la alimentación del ganado en Argentina. Es necesario disponer de información en la zona de influencia de la Facultad de Ciencias Veterinarias de la Universidad Nacional de La Pampa acerca de la adaptación y comportamiento productivo de variedades de alfalfa ofrecidas en el mercado. Por ello, en la Unidad Demostrativa, Experimental y Productiva de dicha institución, en la zona de General Pico, se realiza un ensayo de dos cultivares comerciales de alfalfa de distinto grado de latencia (intermedia y corta), aplicando dos densidades de siembra (8 y 16 kg/ha) y dos dosis de fertilización (0 y 60 kg de superfostato/ha). Los resultados productivos y económicos del primer año de producción demostraron, en promedio, que la variedad de latencia intermedia produjo mayor cantidad de materia seca que la de latencia corta (P<0,05), pero no se observaron diferencias significativas entre densidades de siembra. Se encontró una tendencia a favor de las parcelas fertilizadas vs. las no fertilizadas. El análisis económico mostró diferencias significativas entre variedad y densidades, no así respecto a la fertilización. En el segundo año de producción se repite una mayor producción de la variedad de latencia intermedia sobre la de latencia corta (9.450 kg/ha vs. 9.361 kg/ha) y de las fertilizadas vs. las no fertilizadas (9.624 kg/ha vs. 9.187 kg/ha). Asimismo, tuvieron una mejor producción las alfalfas sembradas con una densidad de 16 kg/ha sobre las sembradas con 8 kg/ha (9.558 kg/ha vs. 9.253 kg/ha). El tercer año de producción tubo una merma importante de producción en todas sus representaciones producto principalmente de la sequía que afectó la región. Con un corte menos que el año anterior, se invirtieron los resultados en cuanto a latencia y fertilización. Finalmente, la producción total del ciclo (tomando en cuenta el cuarto y último año de su producción), se mantuvo la tendencia de la variedad de latencia intermedia sobre la de latencia corta (24.104 kg/ha vs. 22.536 kg/ha) y de las fertilizadas vs. las no fertilizadas (23.357 kg/ha vs. 23.283 kg/ha). Asimismo, tuvieron una mejor producción las alfalfas sembradas con una densidad de 16 kg/ha sobre las sembradas con 8 kg/ha (23.407 kg/ha vs. 23.232 kg/ha). El análisis económico por tonelada de materia seca marca diferencias principalmente entre densidades con un valor de 3,77 dólares para los 16 kg/ha vs un valor de 2,81 dólares para los 8 kg/ha (principalmente por el costo de la semilla); no así respecto a variedad y fertilización
Magnetic control of DTT alternative plasma configurations
One of the main challenges concerning next generation tokamaks (such as DEMO)
will be the development of a heat and power exhaust system able to withstand
the large loads expected in the divertor region. A dedicated Divertor Tokamak
Test (DTT) facility has been proposed in the EUROfusion Roadmap, with the aim
of testing unconventional solutions, such as advanced magnetic configurations
and liquid metal divertors. Magnetic control of alternative plasma
configurations, such as the X-Divertor, will play a key role in the solution of
the heat exhaust and yet can be a challenging point, due to increased
sensitivity introduced by secondary x-points. To overcome the complications
introduced by secondary x-points in advanced plasma shapes, magnetic control in
DTT is achieved by resolving to the eXtreme Shape Controller, in order to
control both the plasma shape and the secondary x-point position
STUDIO PROSPETTICO PER LA VALUTAZIONE DEI FATTORI DI RISCHIO DELLE CADUTE NELLE RESIDENZE SANITARIE ASSISTENZIALI (RSA) PER ANZIANI. FALL RISK ASSESSMENT IN INSTITUTIONALIZED ELDERLY LONGITUDINAL STUDY - FRAILS
Keywords: falls; risk factors; older; nursing homes
Introduction
Falls are common in older persons and sometimes lead to unfavorable outcomes, as traumas and hip fracture. The elderly living in nursing homes are at greater risk of injury resulting from a fall, due to a higher degree of frailty. Some factors are more associated to falls and especially to traumatic falls: functional deficiency, use of aids for walking, osteoporosis, postural instability, deficit of balance and gait; chronic disease, cognitive impairment, and polytherapy use of psychotropic drugs, new environments, previous falls (1,2). The guidelines on the prevention of falls in older people recommend the evaluation of risk factors, as a key element to prevent further falls and, especially, trauma secondary to falls (3,4).
Aim of the study and Methods
In order to know the risk factors associated with falls, the incidence of falls and traumatic falls in people cared for in nursing home, it was performed a prospective observational study with 12 months of follow up (October 2013 - September 2014).
For every resident we detect the functional, cognitive and nutritional status, comorbidity, number and type of drugs, risk of falling, number and outcomes of falls. It was used univariate and multivariate logistic regression to estimate the predictive role of clinical variables on people who had fallen. Results were considered significant at a level of p value <0.05 and a confidence interval of 95%, with two-tailed test.
Results
The study, carried out in two nursing homes in Milan, involved 409 residents of which 331 in ordinary units, and in 78 specialized units for dementia, predominantly women (82%) with a mean age of 83 years (\ub1 9.4).
Most of the residents had a total dependence (43.8%) or severe (32.8%) in the activities of daily living (Barthel index median: 26) and mild (11%), moderate (20%) or severe (42%) cognitive impairment, detected by the Mini Mental State Examination. Residents showed an average 6.30 (\ub1 2.2) disease with moderate severity (2.24 \ub1 0.47), derived by the average of 13 categories of the Cumulative Illness Rating Scale. In 117 residents it was detected a risk of malnutrition: moderate (11.5%) or high (17.1%), using the Malnutrition Universal Screening Tool. However only 67 residents were underweight (body mass index: 0 to 18.49).
In one of the nursing home 83% (185/223) had a risk of falling, with a median value of 5, detected by the Conley Scale ( 652 values are indicative of risk). In the second RSA, based on the scores of Tinetti Balance Assessment Tool, 106/186 residents were at risk of falling, including 31.2% lower and 25.8% higher, while 80 residents were not considered at risk, because they did not walk. About 40% of the residents were restrained with one or more restraint and at 286/409 residents (70%) were applied to bilateral bed rails.
The residents took an average of 8.5 (\ub1 3.4) active ingredients per day (median 8, range 0-19), of which an average of 4.8 (\ub1 2.2) drugs at risk (median 5, range 0-14 ) which include cardiovascular drugs, agents on metabolism/alimentary tract and acting on the nervous system.
In the observation period 111/409 (27%) residents fell, of which 54 had a lesion from mild to severe. It was detected an average of 1.26 (\ub1 0.48) falls/resident, with a range from 1 to 10 and a higher percentage (and statistically significant) of falls among males (28/75) compared with women (83/334 ) and the residents cared for in special unit for dementia (29/78) than residents in ordinary units (83/331).
Multivariate logistic regression confirmed statistically significant risk factors: type of nursing home unit, level of dependence in activities of daily living, previous falls, psycholeptics. Residents with a lower dependence in activities of daily living (Barthel> 27), compared to those with a total dependence, had a risk more than four times significantly higher (OR: 4.75; 95% CI 2.50 to 9.02 p: 0.000). Previous falls bring a three-fold risk of falling (OR: 3.34; 95% CI 1.5 to 7.44; P 0.003), instead the residents cared for in specialized units presented a two-fold risk (OR: 2.22; 95% CI 1.16 to 4.27; P 0.016). Although it was less significant, there was a greater risk of falling in people taking antipsychotic drugs (OR: 1.66; 95% CI 0.99 to 2.76; p: 0.052).
Conclusion
The prevalence of falls is quite in line with results described in literature. A lesser dependency in ADL seems to have a high predictive role, although in some studies was observed an opposite direction. The results confirmed that a previous fall should be taken as alert of further falls, although it is considered a predictor of more than one risk factor, and as such it cannot be eliminated or preventable, but can direct a first level of screening.
The risk assessment should be the first step to predict recurrent falls, although it should accept some degree of risk, because it is not possible to eliminate all of the falls. The results of this study will allow to direct the development of new research hypotheses, including the evaluation of multidimensional programs for the prevention of traumatic falls in nursing home, specifically targeted to major risk factors found in the elderly, which include the improvement / maintenance of functional ability and medication review
Assessment of the resistance model uncertainties in plane stress NLFEA of cyclically loaded reinforced concrete systems
The present work is devoted to estimate the resistance model uncertainty within plane stress non-linear finite element analyses (NLFEAs) of reinforced concrete structures subjected to cyclic loads. Specifically, various shear walls experimentally tested are considered for the investigation. The comparison between the plane stress NLFE structural model results and the experimental outcomes is carried out considering the possible modelling hypotheses available to describe the mechanical behaviour of reinforced concrete members subjected to cyclic loads. Several NLFE structural models are defined for each experimental test in order to investigate the resistance model uncertainty
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