RC beams strengthened in shear using the Embedded Through-Section technique: experimental results and analytical formulation

The Embedded Through-Section (ETS) is a recent strengthening technique that has been developed to retrofit existing reinforced concrete (RC) elements with shear reinforcement deficiencies. This technique is based on the execution of holes drilled through the element cross section, in which steel or fiber reinforced polymer (FRP) bars are inserted and bonded to the surrounding concrete with an epoxy adhesive. An experimental program was carried out with RC T-cross section beams strengthened in shear using steel ETS bars. The influence of the inclination and shear strengthening ratio of ETS on the shear strengthening efficiency was evaluated, as well as the interaction of ETS bars with existing steel stirrups. Two different analytical models are presented in this paper in order to calculate the contribution of ETS to shear resistance. The first model follows an empirical approach (experimental-based approach), while the second model takes into account the physical and mechanical principles of the technique (mechanical-based approach). The predictive performance of both models is assessed by using the experimental results.The authors wish to acknowledge the support provided by the CutInov project QREN n. 38780 supported by ADI, and by the Engineering Department of the University of Ferrara

Decoding information for grasping from the macaque dorsomedial visual stream

Neurodecoders have been developed by researchers mostly to control neuroprosthetic devices, but also to shed new light on neural functions. In this study, we show that signals representing grip configurations can be reliably decoded from neural data acquired from area V6A of the monkey medial posterior parietal cortex. Two Macaca fascicularis monkeys were trained to perform an instructed-delay reach-to-grasp task in the dark and in the light toward objects of different shapes. Population neural activity was extracted at various time intervals on vision of the objects, the delay before movement, and grasp execution. This activity was used to train and validate a Bayes classifier used for decoding objects and grip types. Recognition rates were well over chance level for all the epochs analyzed in this study. Furthermore, we detected slightly different decoding accuracies, depending on the task's visual condition. Generalization analysis was performed by training and testing the system during different time intervals. This analysis demonstrated that a change of code occurred during the course of the task. Our classifier was able to discriminate grasp types fairly well in advance with respect to grasping onset. This feature might be important when the timing is critical to send signals to external devices before the movement start. Our results suggest that the neural signals from the dorsomedial visual pathway can be a good substrate to feed neural prostheses for prehensile actions

Experimental tests and numerical simulations on the mechanical response of RC slabs externally strengthened by passive and prestressed FRP strips

Externally Bonded Reinforcement on Groove (EBROG) method has been introduced to enhance the bond resistance of FRP strips to concrete. It has demonstrated that EBROG generally outperforms EBR in terms of loadtransfer capacity between FRP strips and concrete. The present study aims to further demonstrate the potential of EBROG applied for flexural strengthening. A specimen reinforced according to the EBR solution and a nominally equal one reinforced through the EBROG system are first presented. Then, the performance of a newly fully-composite mechanical end anchorage for prestressed FRP strip to be used in conjunction with the EBROG method is investigated. The experimental results show that the premature debonding observed in EBR is avoided by EBROG in the case of "passive" FRP strips. Moreover, the combination of EBROG and end anchorage demonstrates their effectiveness, as the pre-stressed slab exhibits the full exploitation of the FRP up to rupture. Numerical analyses, carried out by means of a model already presented by the authors, show that the structural response of the tested slabs can be simulated in a very accurate manner if consistent assumptions are made in terms of bond-slip laws adopted to describe the interaction between FRP and concrete in EBR and EBROG

Embedded Through-Section shear strengthening technique using steel and CFRP bars in RC beams of different percentage of existing stirrups

The Embedded Through-Section (ETS) technique is a promising technique for the shear strengthening of existing (RC) elements. According to this technique, holes are drilled through the beam section, and bars of steel or FRP material are introduced into these holes and bonded to the concrete with adhesive materials. An experimental program was carried out with RC T-cross section beams strengthened in shear using the ETS steel bars and ETS CFRP rods. The research is focused on the evaluation of the ETS efficiency on beams with different percentage of existing internal transverse reinforcement (ρsw=0.0%, ρsw=0.1% and ρsw=0.17%). The effectiveness of different ETS strengthening configurations was also investigated. The good bond between the strengthening ETS bars and the surrounding concrete allowed the yield initiation of the ETS steel bars and the attainment of high tensile strains in the ETS CFPR rods, leading to significant increase of shear capacity, whose level was strongly influenced by the inclination of the ETS bars and the percentage of internal transverse reinforcement.The authors wish to acknowledge Elletipi S.r.l. (Ferrara, Italy) for supporting the experimental program, Interbau S.r.l. (Milano, Italy) for applying the ETS strengthening system, BASF company Italy for providing the CFRP rods and the ENDIF Geomatic Group (University of Ferrara, Italy) for monitoring the experimental program, as well as the support provided by FCT (PTDC/ECM/114511/2009). The authors wish also acknowledge the Engineering Department of the University of Ferrara for its financial support

Covert Shift of Attention Modulates the Ongoing Neural Activity in a Reaching Area of the Macaque Dorsomedial Visual Stream

Background: Attention is used to enhance neural processing of selected parts of a visual scene. It increases neural responses to stimuli near target locations and is usually coupled to eye movements. Covert attention shifts, however, decouple the attentional focus from gaze, allowing to direct the attention to a peripheral location without moving the eyes. We tested whether covert attention shifts modulate ongoing neuronal activity in cortical area V6A, an area that provides a bridge between visual signals and arm-motor control. Methodology/Principal Findings: We performed single cell recordings from 3 Macaca Fascicularis trained to fixate straight-head, while shifting attention outward to a peripheral cue and inward again to the fixation point. We found that neurons in V6A are influenced by spatial attention. The attentional modulation occurs without gaze shifts and cannot be explained by visual stimulations. Visual, motor, and attentional responses can occur in combination in single neurons. Conclusions/Significance: This modulation in an area primarily involved in visuo-motor transformation for reaching may form a neural basis for coupling attention to the preparation of reaching movements. Our results show that cortical processes of attention are related not only to eye-movements, as many studies have shown, but also to arm movements, a finding that has been suggested by some previous behavioral findings. Therefore, the widely-held view that spatial attention is tightly intertwined with - and perhaps directly derived from - motor preparatory processes should be extended to a broader spectrum of motor processes than just eye movements

Parallel hardware architectures for the cryptographic Tate pairing

Identity-based cryptography uses pairing functions, which are sophisticated bilinear maps defined on elliptic curves. Computing pairings efficiently in software is presently a relevant research topic. Since such functions are very complex and slow in software, dedicated hard- ware (HW) implementations are worthy of being stud- ied, but presently only very preliminary research is avail- able. This work affords the problem of designing paral- lel dedicated HW architectures, i.e.,co-processors, for the Tate pairing, in the case of the Duursma-Lee algorithm in characteristic 3. Formal scheduling methodologies are applied to carry out an extensive exploration of the archi- tectural solution space, evaluating the obtained structures by means of different figures of merit such as computation time, circuit area and combinations thereof.Comparisons with the (few) existing proposals are carried out, show- ing that a large space exists for the efficient parallelHW computation of pairings

Neural coding of action in three dimensions: Task- and time-invariant reference frames for visuospatial and motor-related activity in parietal area V6A

Goal-directed movements involve a series of neural computations that compare the sensory representations of goal location and effector position, and transform these into motor commands. Neurons in posterior parietal cortex (PPC) control several effectors (e.g., eye, hand, foot) and encode goal location in a variety of spatial coordinate systems, including those anchored to gaze direction, and to the positions of the head, shoulder, or hand. However, there is little evidence on whether reference frames depend also on the effector and/or type of motor response. We addressed this issue in macaque PPC area V6A, where previous reports using a fixate-to-reach in depth task, from different starting arm positions, indicated that most units use mixed body/hand-centered coordinates. Here, we applied singular value decomposition and gradient analyses to characterize the reference frames in V6A while the animals, instead of arm reaching, performed a nonspatial motor response (hand lift). We found that most neurons used mixed body/hand coordinates, instead of \u201cpure\u201d body-, or hand-centered coordinates. During the task progress the effect of hand position on activity became stronger compared to target location. Activity consistent with body-centered coding was present only in a subset of neurons active early in the task. Applying the same analyses to a population of V6A neurons recorded during the fixate-to-reach task yielded similar results. These findings suggest that V6A neurons use consistent reference frames between spatial and nonspatial motor responses, a functional property that may allow the integration of spatial awareness and movement control

Efficient software implementation of AES on 32-bit platforms

Rijndael is the winner algorithm of the AES contest; therefore it should become the most used symmetric-key cryptographic algorithm. One important application of this new standard is cryptography on smart cards. In this paper we present an optimisation of the Rijndael algorithm to speed up execution on 32-bits processors with memory constraints, such as those used in smart cards. First a theoretical analysis of the Rijndael algorithm and of the proposed optimisation is discussed, and then simulation results of the optimised algorithm on different processors are presented and compared with other reference implementations, as known from the technical literature

Decoding information for grasping from the macaque dorsomedial visual stream

Neurodecoders have been developed by researchers mostly to control neuroprosthetic devices, but also to shed new light on neural functions. In this study, we show that signals representing grip configurations can be reliably decoded from neural data acquired from area V6A of the monkey medial posterior parietal cortex. Two Macaca fascicularis monkeys were trained to perform an instructed-delay reach-to-grasp task in the dark and in the light toward objects of different shapes. Population neural activity was extracted at various time intervals on vision of the objects, the delay before movement, and grasp execution. This activity was used to train and validate a Bayes classifier used for decoding objects and grip types. Recognition rates were well over chance level for all the epochs analyzed in this study. Furthermore, we detected slightly different decoding accuracies, depending on the task's visual condition. Generalization analysis was performed by training and testing the system during different time intervals. This analysis demonstrated that a change of code occurred during the course of the task. Our classifier was able to discriminate grasp types fairly well in advance with respect to grasping onset. This feature might be important when the timing is critical to send signals to external devices before the movement start. Our results suggest that the neural signals from the dorsomedial visual pathway can be a good substrate to feed neural prostheses for prehensile actions

Integer compositions and syntactic trees of repeat-until programs

In this work we study some properties of integer compositions in connection with the recognition of rational trace languages. In particular, we introduce some operations defined on integer compositions and present procedures for their computation that work in linear or in quadratic time. These procedures turn out to be useful in the analysis of syntactic trees of certain regular expressions, called repeat-until expressions, which intuitively represent programs of instructions nested in repeat-until loops. Our main aim is to show how, in some cases, such an analysis allows us to design algorithms for the recognition of (rational) trace languages defined by repeat-until expressions, which work in quadratic time independently of the concurrency relation