In this paper we consider the postural stability problem for nonlinearly actuated quasi-static biped robots, both with respect to the joint angular positions and also with reference to the gripping ...effect between the foot/feet against the ground during robot locomotion. Zero moment point based mathematical models are developed to establish a relationship between the robot state variables and the stability margin of the foot (feet) contact surface and the supporting ground. Then, in correspondence with the developed dynamical model and its associated uncertainty, and in the presence of non-modeled robot mechanical structure vibration modes, we propose a robust control architecture that uses two cascade regulators. The overall robust control system consists of a nonlinear robust variable structure controller in an inner feedback loop for joint trajectory tracking, and an
H∞ linear robust regulator in an outer, direct zero moment point feedback loop to ensure the foot-ground contact stability. The effectiveness of this cascade controller is evaluated using a simplified prototype of a nonlinearly actuated biped robot in double support placed on top of a one-degree-of-freedom mobile platform and subjected to external disturbances. The achieved experimental results have revealed that the simplified prototype is successfully stabilized.
BACKGROUND:Esophageal motility abnormalities have been observed in patients with gastroesophageal reflux disease.
GOALS:The aim of the present study was to determine if esophageal motor disorders in ...patients with a positive response to the omeprazole test are related to the existence of reflux or they are concomitant findings.
STUDY:A 24-hour pH monitoring and a stationary manometry were performed on 128 patients49 of them had normal manometry, 31 hypotensive lower esophageal sphincter, 29 motor disorder in esophageal body, and 19 hypotensive lower esophageal sphincter and motor disorder in esophageal body.
RESULTS:We found an association between the presence of abnormal reflux and motor disorder in esophageal body (χ test; P < 0.05). However, ineffective esophageal motility was the disorder most strongly related to reflux, whereas the hypercontractile disorders were not clearly attributed to it.
CONCLUSIONS:Esophageal manometric abnormalities should be considered cautiously before considering a motor disorder as a consequence of abnormal reflux.
Orthogonal frequency-division multiplexing (OFDM) systems, such as the new wireless standards or the schemes proposed for third-generation (3G) evolution, exhibit great sensitivity to the effects of ...phase noise and the time-varying propagation channel, which can introduce interchannel interference (ICI) due to the loss of orthogonality among subcarriers. In this paper, joint channel estimation and ICI reduction schemes are investigated, which compensate the effects of phase noise and multipath channel in a realistic scenario, where the channel is not assumed perfectly known, whereas its estimation is obtained by combining a decision-feedback scheme and a pilot-aided estimator. We propose a technique for ICI compensation that has reduced complexity by only considering the most significant terms of ICI.
Here we describe an eight-year-old miniature schnauzer (MS) dog from Brazil with Persistent Mullerian Duct Syndrome (PMDS) and the single base pair substitution in AMHR2 exon 3, first detected in ...this breed in the USA. This finding is evidence of mutation dissemination to South America. In PMDS, a type of XY Disorder of Sex Development (DSD), dogs with a male karyotype and external phenotype also have a uterus, oviducts, and a cranial vagina internally. Approximately half of PMDS MS are unilaterally or bilaterally cryptorchid and many develop pyometra and/or Sertoli cell tumor. Bilateral Sertoli cell testicular tumors were present in this case, and the dog died a few days after surgical castration and hysterectomy. Although the karyotype was compatible with male chromosomal sex, a Robertsonian translocation was also identified, which may be an incidental finding. This report emphasizes the importance of cytogenetic and molecular genetic analyses, along with clinical examination, to identify chromosomal or genetic variations associated with canine PMDS. These are helpful tools to obtain early diagnosis in the MS, which is important to improve health outcomes for affected dogs and to reduce the prevalence of PMDS and cryptorchidism in this breed by avoiding the mating of carriers.
The fifth-generation (5G) of cellular communications is expected to be deployed in the next years to support a wide range of services with different demands of peak data rates, latency and quality of ...experience (QoE). In this work, we propose a novel approach for radio network dimensioning (RND), named as Heuristic RND (HRND), which uses real open data in the network dimensioning process. This procedure, named as NetDataDrilling, provides the dimensioning target area by means of network data selection and visualization from the existing infrastructure. Moreover, the proposed NetDimensioning heuristic considers the necessary parameters of numerology and bandwidth parts (BWP) supported by New Radio (NR) to provide a balanced network design mediating among the requirements of coverage, capacity, QoE and cost. The proposed HRND is based on the novel quality of experience (QoE) parameter ζ by probabilistically characterizing the 5G radio resource control (rrc) states to ensure the availability of peak data rates for the MNO's required percentage of the time. The simulation results show the fulfilment of QoE and load balancing parameters with significant cost savings compared to the conventional RND methodology.
Ultrasound (US) has an important role in musculoskeletal (MSK) evaluation, allowing the study of muscle morphology and function. Muscle thickness (MT) and muscle echo-intensity (EI) are two important ...parameters that may quantify muscle structural adaptations to a variety of stimuli. The aim was to explore the potential of quantitative US imaging for assessing the adaptations and responses of the muscle tissue to increased contractile activity using B-mode US. This study was centred on the quadriceps femoris muscle contractile activity on MT and EI.
Twenty-eight young male adults participated in the study, divided in a control group and two training groups performing concentric or eccentric strength training, respectively. The effect of a 15-week strength program was studied on MT and EI in several regions of the heads of the quadriceps femoris using B-mode US. All images acquisitions and measurements were done by the same experience sonographer.
Strength training resulted in an increase of MT at all muscles and sites (p < 0.05), except the VM. Strength training failed in changing EI in most of the quadriceps femoris, except in the VI and some regions of the VL. No statistically significant differences were observed in our quantitative US parameters between concentric and eccentric training (p > 0.05).
These results emphasise the value of MT as a quantifiable muscle US method for evaluating muscle adaptation to exercise training. However, the inconsistency of the EI values indicates that more studies are needed to develop it as an accurate diagnostic tool.
•Both concentric and eccentric strength training produced similar results in MT and EI.•After strength training, changes existed in MT between different regions of the muscles.•MT is a consistently accurate tool for measuring change in muscle.•After training, there were no consistent changes on the quadriceps femoris EI values.•EI values showed that more studies are needed to develop it as an accurate US tool.
In peripheral nerves MSCs can modulate Wallerian degeneration and the overall regenerative response by acting through paracrine mechanisms directly on regenerating axons or upon the nerve-supporting ...Schwann cells. In the present study, the effect of human MSCs from Wharton’s jelly (HMSCs), differentiated into neuroglial-like cells associated to poly (DL-lactide-ε-caprolactone) membrane, on nerve regeneration, was evaluated in the neurotmesis injury rat sciatic nerve model. Results in vitro showed successful differentiation of HMSCs into neuroglial-like cells, characterized by expression of specific neuroglial markers confirmed by immunocytochemistry and by RT-PCR and qPCR targeting specific genes expressed. In vivo testing evaluated during the healing period of 20 weeks, showed no evident positive effect of HMSCs or neuroglial-like cell enrichment at the sciatic nerve repair site on most of the functional and nerve morphometric predictors of nerve regeneration although the nociception function was almost normal. EPT on the other hand, recovered significantly better after HMSCs enriched membrane employment, to values of residual functional impairment compared to other treated groups. When the neurotmesis injury can be surgically reconstructed with an end-to-end suture or by grafting, the addition of a PLC membrane associated with HMSCs seems to bring significant advantage, especially concerning the motor function recovery.
This paper provides the results of a complete study about the indoor radio propagation channel at 17 GHz. Wideband parameters, as coherence bandwidth or rms delay spread, and coverage are analyzed ...for the design of an OFDM-based broadband WLAN. A discussion of some adequate system parameters is also included. The report presents the characterization results as well as a previously developed indoor channel model; both of them have been checked and compared to bibliography results in order to verify their reliability.
Interest in climbing and walking robots (CLAWAR) has increased remarkably over recent years. Novel solutions for complex and very diverse application fields (exploration/intervention in severe ...environments, personal services, emergency rescue operations, transportation, entertainment, medical, etc.), have been anticipated by great progress in this area of robotics. This book contains the proceedings of the 7th Climbing and Walking Robots 2004 (CLAWAR 2004) Conference, offering the international scientific community one of the most excellent forums for academics, researchers and industrialists interested in this motivating area of climbing and walking robots. It provides a wide forum of original state-of-the-art contributions from various industrial and new/emerging research fields, presenting a full picture of climbing and walking robots. The conference, held in Madrid, Spain, September 22-24 2004, was organized by the Thematic Network 'CLAWAR 2' and funded by the European Commission under the GROWTH Program.
We focus on the mean achievable rate per user of the coordinated base station downlink transmission in a clustered cellular environment, with transmit power constraints at the base stations. Block ...Diagonalization is employed within the cluster to remove interference among users while the interference from other clusters remains. The average achievable rate per user is evaluated considering the effects of the propagation channel and the interference and a theoretical framework is presented to provide its analytical expression, validated by simulation results with different power allocation schemes. As an application, the number of cells of the cluster that maximizes the mean achievable rate per user is investigated. It can be seen that in most of the cases a reduced cluster size, close to seven cells, guarantees a rate very close to the maximum achievable.
PDF
