Brain-Computer Interface meets ROS: A robotic approach to mentally drive telepresence robots

This paper shows and evaluates a novel approach to integrate a non-invasive Brain-Computer Interface (BCI) with the Robot Operating System (ROS) to mentally drive a telepresence robot. Controlling a mobile device by using human brain signals might improve the quality of life of people suffering from severe physical disabilities or elderly people who cannot move anymore. Thus, the BCI user can actively interact with relatives and friends located in different rooms thanks to a video streaming connection to the robot. To facilitate the control of the robot via BCI, we explore new ROS-based algorithms for navigation and obstacle avoidance in order to make the system safer and more reliable. In this regard, the robot exploits two maps of the environment, one for localization and one for navigation, and both are used as additional visual feedback for the BCI user to control the robot position. Experimental results show a decrease of the number of commands needed to complete the navigation task, suggesting a reduction user’s cognitive workload. The novelty of this work is to provide a first evidence of an integration between BCI and ROS that can simplify and foster the development of software for BCI driven robotics devices

Free Differential Algebras and Pure Spinor Action in IIB Superstring Sigma Models

In this paper we extend to the case of IIB superstring sigma models the method proposed in hep-th/10023500 to derive the pure spinor approach for type IIA sigma models. In particular, starting from the (Free) Differential Algebra and superspace parametrization of type IIB supergravity, extended to include the BRST differential and all the ghosts, we derive the BRST transformations of fields and ghosts as well as the standard pure spinor constraints for the ghosts $\lambda$ related to supersymmetry. Moreover, using the method first proposed by us, we derive the pure spinor action for type IIB superstrings in curved supergravity backgrounds (on shell), in full agreement with the action first obtained by Berkovits and Howe.Comment: 24 page

A Twistor Formulation of the Non-Heterotic Superstring with Manifest Worldsheet Supersymmetry

We propose a new formulation of the $D=3$ type II superstring which is manifestly invariant under both target-space $N=2$ supersymmetry and worldsheet $N=(1,1)$ super reparametrizations. This gives rise to a set of twistor (commuting spinor) variables, which provide a solution to the two Virasoro constraints. The worldsheet supergravity fields are shown to play the r\^ole of auxiliary fields.Comment: 21p., LaTe

In Vitro Production of Calcified Bone Matrix onto Wool Keratin Scaffolds via Osteogenic Factors and Electromagnetic Stimulus

Pulsed electromagnetic field (PEMF) has drawn attention as a potential tool to improve the ability of bone biomaterials to integrate into the surrounding tissue. We investigated the effects of PEMF (frequency, 75 Hz; magnetic induction amplitude, 2 mT; pulse duration, 1.3 ms) on human osteoblast-like cells (SAOS-2) seeded onto wool keratin scaffolds in terms of proliferation, differentiation, and production of the calcified bone extracellular matrix. The wool keratin scaffold offered a 3D porous architecture for cell guesting and nutrient diffusion, suggesting its possible use as a filler to repair bone defects. Here, the combined approach of applying a daily PEMF exposure with additional osteogenic factors stimulated the cells to increase both the deposition of bone-related proteins and calcified matrix onto the wool keratin scaffolds. Also, the presence of SAOS-2 cells, or PEMF, or osteogenic factors did not influence the compression behavior or the resilience of keratin scaffolds in wet conditions. Besides, ageing tests revealed that wool keratin scaffolds were very stable and showed a lower degradation rate compared to commercial collagen sponges. It is for these reasons that this tissue engineering strategy, which improves the osteointegration properties of the wool keratin scaffold, may have a promising application for long term support of bone formation in vivo

Use of electrical bioimpedance analysis to evaluate the quality of bovine raw milk

The objective of the present study was to use electrical bioimpedance analysis (BIA) as an alternative method of evaluating the quality of bovine raw milk. Fourteen lactating purebred Dutch cows were used. For the analyses of milk quality and electrical bioimpedance, 140 ml milk per mammary quarter and a homogeneous sample of each animal were collected, totalling 70 samples. The criteria used to evaluate milk quality consisted of somatic cell count (CCS), total bacterial count (CBT), fat, protein, lactose, total solids (ST) and non-greasy solids (SNG) as required by IN No 62/2011. A monofrequential 50 kHz and 800 μA alternating current generator was used for electrical BIAs. The temperature of the raw milk was 5 °C for all samples. Primary resistance and reactance readings were obtained. From these values, the values of impedance, conductance and phase angle were obtained. Correlation analyses were performed to determine the variables used by the regression analyses. The regression analysis was performed using raw milk components as dependent variables and BIA measurements as independent variables. Lactose, ST and SNG were the components of milk that correlated best and presented moderate prediction equations in relation to BIA variables. The prediction equations using resistance showed R2 of 0.42 and 0.45 for ST and SNG, respectively. In the prediction equation for ST and SNG, the conductance resulted in R2 of 0.45, and 0.45, respectively. Regarding impedance, the R2 of 0.42 and 0.45 were obtained for the predicted equations ST and SNG, respectively. Thus, it can be concluded that BIA has the potential to estimate the composition and quality of bovine raw milk.Keywords: conductance, impedance, milk compositio

Pure Spinor Approach to Type IIA Superstring Sigma Models and Free Differential Algebras

This paper considers the Free Differential Algebra and rheonomic parametrization of type IIA Supergravity, extended to include the BRS differential and the ghosts. We consider not only the ghosts lambda's of supersymmetry but also the ghosts corresponding to gauge and Lorentz transformations. In this way we can derive not only the BRS transformations of fields and ghosts but also the standard pure spinor constraints on lambda's. Moreover the formalism allows to derive the action for the pure spinor formulation of type IIA superstrings in a general background, recovering the action first obtained by Berkovits and Howe.Comment: 1+23 pages, v2: added clarifications and a reference, misprints corrected, v3: presentation improved, results unchange