Control of synchronization regimes in networks of mobile interacting agents

We investigate synchronization in a population of mobile pulse-coupled agents with a view towards implementations in swarm robotics systems and mobile sensor networks. Previous theoretical approaches dealt with range and nearest neighbor interactions. In the latter case, a synchronization-hindering regime for intermediate agent mobility was found. In the present work, we investigate the robustness of this intermediate regime under practical scenarios. We show that synchronization in the intermediate regime can be predicted by means of a suitable metric of the phase response curve. Furthermore, we study more realistic K-nearest neighbors and cone of vision interactions, showing that it is possible to control the extent of the synchronization-hindering region by appropriately tuning the size of the neighborhood. To assess the effect of noise, we analyze the propagation of perturbations over the network and draw an analogy between the response in the hindering regime and stable chaos. Our findings reveal the conditions for the control of clock or activity synchronization of agents with intermediate mobility. In addition, the emergence of the intermediate regime is validated experimentally using a swarm of physical robots interacting with cone of vision interactions

Discovery of a wide companion near the deuterium burning mass limit in the Upper Scorpius association

We present the discovery of a companion near the deuterium burning mass limit located at a very wide distance, at an angular separation of 4.6+/-0.1 arcsec (projected distance of ~ 670 AU) from UScoCTIO108, a brown dwarf of the very young Upper Scorpius association. Optical and near-infrared photometry and spectroscopy confirm the cool nature of both objects, with spectral types of M7 and M9.5, respectively, and that they are bona fide members of the association, showing low gravity and features of youth. Their masses, estimated from the comparison of their bolometric luminosities and theoretical models for the age range of the association, are 60+/-20 and 14^{+2}_{-8} MJup, respectively. The existence of this object around a brown dwarf at this wide orbit suggests that the companion is unlikely to have formed in a disk based on current planet formation models. Because this system is rather weakly bound, they did not probably form through dynamical ejection of stellar embryos.Comment: 10 pages, including 4 figures and 2 table

Computing the Singularities of Rational Surfaces

Given a rational projective parametrization \cP(\ttt,\sss,\vvv) of a rational projective surface \cS we present an algorithm such that, with the exception of a finite set (maybe empty) \cB of projective base points of \cP, decomposes the projective parameter plane as \projdos\setminus \cB=\cup_{k=1}^{\ell} \cSm_k such that if (\ttt_0:\sss_0:\vvv_0)\in \cSm_k then \cP(\ttt_0,\sss_0,\vvv_0) is a point of \cS of multiplicity $k$.Comment: In this new version, we only have changed the thanks. In particular, we have written: This work was developed, and partially supported, under the research project MTM2008-04699-C03-01 "Variedades param\'etricas: algoritmos y aplicaciones", Ministerio de Ciencia e Innovaci\'on, Spain and by "Fondos Europeos de Desarrollo Regional" of the European Unio

High spatial resolution and high contrast optical speckle imaging with FASTCAM at the ORM

In this paper, we present an original observational approach, which combines, for the first time, traditional speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high contrast (1e-5) within 0.5 to 2 arcseconds around a bright star. The post-processing step is based on wavelet filtering an has analogy with edge enhancement and high-pass filtering. Our I-band on-sky results with the 2.5-m Nordic Telescope (NOT) and the lucky imaging instrument FASTCAM show that we are able to detect L-type brown dwarf companions around a solar-type star with a contrast DI~12 at 2" and with no use of any coronographic capability, which greatly simplifies the instrumental and hardware approach. This object has been detected from the ground in J and H bands so far only with AO-assisted 8-10 m class telescopes (Gemini, Keck), although more recently detected with small-class telescopes in the K band. Discussing the advantage and disadvantage of the optical regime for the detection of faint intrinsic fluxes close to bright stars, we develop some perspectives for other fields, including the study of dense cores in globular clusters. To the best of our knowledge this is the first time that high contrast considerations are included in optical speckle imaging approach.Comment: Proceedings of SPIE conference - Ground-based and Airborne Instrumentation for Astronomy III (Conference 7735), San Diego 201

LAGOVirtual: A Collaborative Environment for the Large Aperture GRB Observatory

We present the LAGOVirtual Project: an ongoing project to develop platform to collaborate in the Large Aperture GRB Observatory (LAGO). This continental-wide observatory is devised to detect high energy (around 100 GeV) component of Gamma Ray Bursts, by using the single particle technique in arrays of Water Cherenkov Detectors (WCD) at high mountain sites (Chacaltaya, Bolivia, 5300 m a.s.l., Pico Espejo, Venezuela, 4750 m a.s.l., Sierra Negra, Mexico, 4650 m a.s.l). This platform will allow LAGO collaboration to share data, and computer resources through its different sites. This environment has the possibility to generate synthetic data by simulating the showers through AIRES application and to store/preserve distributed data files collected by the WCD at the LAGO sites. The present article concerns the implementation of a prototype of LAGO-DR adapting DSpace, with a hierarchical structure (i.e. country, institution, followed by collections that contain the metadata and data files), for the captured/simulated data. This structure was generated by using the community, sub-community, collection, item model; available at the DSpace software. Each member institution-country of the project has the appropriate permissions on the system to publish information (descriptive metadata and associated data files). The platform can also associate multiple files to each item of data (data from the instruments, graphics, postprocessed-data, etc.).Comment: Second EELA-2 Conference Choroni, Venezuela, November 25th to 27th 200

Comparison of Physiological Responses and Perceived Respiratory Resistance Among Mask Usage During Exercise

Since the beginning of the COVID-19 pandemic, the use of a face mask in public is recommended when social distancing cannot be maintained to decrease the spread of the virus with many fitness facilities requiring their patrons to wear a face mask during exercise. The physiological response of wearing a face mask during exercise is relatively unknown and is speculated among the media resulting in contradicting messages conveyed to the public PURPOSE: The purpose of this study was to determine if a face mask influenced performance (time to exhaustion), physiological responses (heart rate, oxyhemoglobin saturation and temperature) and subjective measurements such as dyspnea, perceived respiratory resistance, and rating of perceived exertion (RPE) during exercise. METHODS: Fifteen healthy males (n =8) and females (n=7) completed three graded exercise treadmill tests with (1) a surgical face mask, (2) a cloth face mask, and (3) no mask randomly with at least 48hrs apart. Heart rate (HR), oxyhemoglobin saturation (SpO2), temperature, RPE, dyspnea, was measured throughout exercise. Participants rated their perceived respiratory resistance for each condition at rest, beginning of exercise, and at fatigue using a 100 mm visual analog scale. RESULTS: Significant differences (p \u3c 0.05) were observed in perceived respiratory resistance between no mask and both surgical and cloth conditions at rest (1.55 ± 2.34mm; 6.33 ± 6.11mm; 9.67 ± 10.77mm respectively) and at the beginning of exercise (5.93 ± 6.64mm; 15.47 ± 12.56mm; 21.07± 15.04mm respectively). During stage 3 of the exercise test, the no mask condition had a significantly lower RPE compared to the cloth mask condition (13.22 ± 2.14;14.60 ± 2.13 respectively). Time to exhaustion was similar for all conditions (mask: 11:51 ± 2:31min; cloth: 11:16 ± 2:24min; surgical: 11:32 ± 2:23min). At all times points, there was no significant (p \u3e 0.05) difference between the conditions for HR, SpO2, temperature, and dyspnea. CONCLUSION: Wearing either a surgical or cloth face mask is safe during exercise in healthy adults and has no effect on HR, SpO2, or body temperature. It appears that wearing a face mask may have a minor influence on subjective measurements such as perceived respiratory resistance or RPE during exercise

Phytoremediation of Heavy Metal Contaminated Wastes From Small-Scale Gold Mining Using Pityrogramma calomelanos

In this study, viability of employing the waste treatment technique for industrial application was conducted by setting up a phytoremediation protocol for field application where heavy metal (Arsenic and Copper) contaminated adsorbents, i.e. coco peat and nanofiber membrane, used for the treatment of wastewater were also included. An arsenic hyperaccumulator, Pityrogramma calomelanos was used for the treatment of mine wastes-tailings, coco peat and nanofiber membrane. Phytoremediation procedure was established by investigating planting parameters namely ; plot height - (9 cm and 15 cm) and planting distance- (15 cm and 20 cm) for a period of five months. Translocation factor and % uptake of As and Cu by ferns were measured. According to the results, % uptake of As and Cu by P. Calomelanos was 0.16 % and 0.01 % and translocation factor of As and Cu was 6.78 and 0.04, respectively. Plant growth factors (root length, frond height and dry weight) in tailings mixture plant boxes and control soil were also determined. Accordingly, P. calomelanos grew well in tailings mixture without the symptom of phytotoxicity. Therefore, P. calomelanos can be used for the phytoremediation of the said heavy metal contaminated mine wastes. Based on this study, 15 cm plot height and 20 cm plant distance were suitable for field experiment although long term research data is required. The overall protocol for the treatment of mine wastes as field experiment was proposed based on the results

Firefly-Inspired Synchronization in Swarms of Mobile Agents

Recently, there has been growing interest in the synchronization of mobile pulse-coupled oscillators. We build on the work by Prignano et al. (Phys. Rev. Lett. 110, 114101) and show that agents that interact exclusively with others in their cone of vision can exhibit different synchronization regimes. Depending on their speed, synchronization emerges as a slow process through spreading of the local coherence, as a fast process where global synchronization dominates, or it is inhibited for a range of intermediate speeds. In addition, we show that, not only the speed of the agents, but also their angle and range of interaction can tune the appearance of this intermediate regime

Modular Hydraulic Propulsion: A Robot that Moves by Routing Fluid Through Itself

This paper introduces the concept of Modular Hydraulic Propulsion, in which a modular robot that operates in a fluid environment moves by routing the fluid through itself. The robot’s modules represent sections of a hydraulics network. Each module can move fluid between any of its faces. The modules (network sections) can be rearranged into arbitrary topologies. We propose a decentralized motion controller, which does not require modules to communicate, compute, nor store information during run-time. We use 3-D simulations to compare the performance of this controller to that of a centralized controller with full knowledge of the task. We also detail the design and fabrication of six 2-D prototype modules, which float in a water tank. Results of systematic experiments show that the decentralized controller, despite its simplicity, reliably steers modular robots towards a light source. Modular Hydraulic Propulsion could offer new solutions to problems requiring reconfigurable systems to move precisely in 3-D, such as inspection of pipes, vascular systems or other confined spaces

Characterization of a putative grapevine Zn transporter, VvZIP3, suggests its involvement in early reproductive development in Vitis vinifera L

Gonzalez, E (reprint author), Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, Chile.Background: Zinc (Zn) deficiency is one of the most widespread mineral nutritional problems that affect normal development in plants. Because Zn cannot passively diffuse across cell membranes, it must be transported into intracellular compartments for all biological processes where Zn is required. Several members of the Zinc-regulated transporters, Iron-regulated transporter-like Protein (ZIP) gene family have been characterized in plants, and have shown to be involved in metal uptake and transport. This study describes the first putative Zn transporter in grapevine. Unravelling its function may explain an important symptom of Zn deficiency in grapevines, which is the production of clusters with fewer and usually smaller berries than normal. Results: We identified and characterized a putative Zn transporter from berries of Vitis vinifera L., named VvZIP3. Compared to other members of the ZIP family identified in the Vitis vinifera L. genome, VvZIP3 is mainly expressed in reproductive tissue - specifically in developing flowers - which correlates with the high Zn accumulation in these organs. Contrary to this, the low expression of VvZIP3 in parthenocarpic berries shows a relationship with the lower Zn accumulation in this tissue than in normal seeded berries where its expression is induced by Zn. The predicted protein sequence indicates strong similarity with several members of the ZIP family from Arabidopsis thaliana and other species. Moreover, VvZIP3 complemented the growth defect of a yeast Zn-uptake mutant, ZHY3, and is localized in the plasma membrane of plant cells, suggesting that VvZIP3 has the function of a Zn uptake transporter. Conclusions: Our results suggest that VvZIP3 encodes a putative plasma membrane Zn transporter protein member of the ZIP gene family that might play a role in Zn uptake and distribution during the early reproductive development in Vitis vinifera L., indicating that the availability of this micronutrient may be relevant for reproductive development