4,196 research outputs found
Barley’s Second Spring as a Model Organism for Chloroplast Research
Barley (Hordeum vulgare) has been widely used as a model crop for studying molecular and physiological processes such as chloroplast development and photosynthesis. During the second half of the 20th century, mutants such as albostrians led to the discovery of the nuclear-encoded, plastid-localized RNA polymerase and the retrograde (chloroplast-to-nucleus) signalling communication pathway, while chlorina-f2 and xantha mutants helped to shed light on the chlorophyll biosynthetic pathway, on the light-harvesting proteins and on the organization of the photosynthetic apparatus. However, during the last 30 years, a large fraction of chloroplast research has switched to the more \u201cuser-friendly\u201d model species Arabidopsis thaliana, the first plant species whose genome was sequenced and published at the end of 2000. Despite its many advantages, Arabidopsis has some important limitations compared to barley, including the lack of a real canopy and the absence of the proplastid-to-chloroplast developmental gradient across the leaf blade. These features, together with the availability of large collections of natural genetic diversity and mutant populations for barley, a complete genome assembly and protocols for genetic transformation and gene editing, have relaunched barley as an ideal model species for chloroplast research. In this review, we provide an update on the genomics tools now available for barley, and review the biotechnological strategies reported to increase photosynthesis efficiency in model species, which deserve to be validated in barley
General rules for bosonic bunching in multimode interferometers
We perform a comprehensive set of experiments that characterize bosonic
bunching of up to 3 photons in interferometers of up to 16 modes. Our
experiments verify two rules that govern bosonic bunching. The first rule,
obtained recently in [1,2], predicts the average behavior of the bunching
probability and is known as the bosonic birthday paradox. The second rule is
new, and establishes a n!-factor quantum enhancement for the probability that
all n bosons bunch in a single output mode, with respect to the case of
distinguishable bosons. Besides its fundamental importance in phenomena such as
Bose-Einstein condensation, bosonic bunching can be exploited in applications
such as linear optical quantum computing and quantum-enhanced metrology.Comment: 6 pages, 4 figures, and supplementary material (4 pages, 1 figure
SLaMA-URM method for the seismic vulnerability assessment of UnReinforced Masonry structures: Formulation and validation for a substructure
An analytical procedure based on the SLaMA (Simplified Lateral Mechanism Analysis) method is proposed for the seismic vulnerability assessment of UnReinforced Masonry (URM) structures. The procedure considers an equivalent frame discretization for the structure (pier, spandrel, and joint elements) and includes: (i) the evaluation of moment‒rotation capacity curves at each pier-spandrel subassembly; (ii) the assessment of the hierarchy of strength in each subassembly; and (iii) the calculation of the structure capacity curve according to the expected failure mechanism. Validation of the proposed SLaMA-URM procedure is achieved in a one-story URM substructure tested under lateral cyclic loading. The analytical predictions are compared with numerical ones from a 2D continuous finite element (FE) model based on a macro-modelling strategy. The flexural capacity of the components is estimated using a monolithic beam analogy, and the results compared with those from traditional sectional analysis. The influence of the substructure geometry on the hierarchy of strength at the subassembly and global levels is investigated. An analytical formulation of the pier-spandrel joint strength is also proposed to be considered in the assessment of the hierarchy of strength. The method is validated for a one-story substructure subjected to lateral in-plane loading. Results, in terms of crack patterns and capacity curves, are in relatively good agreement with the experimental and FE results, even when a bilinear curve approximation is used. The potential of the SLaMA-URM method for the seismic assessment of URM buildings is demonstrated, whose application to a larger URM structure is planned as a subsequent study
Validation of a smart mirror for gesture recognition in gym training performed by a vision-based deep learning system
This paper illustrates the development and validation of a smart mirror for sports training. The application is based on the skeletonization algorithm MediaPipe and runs on an embedded device Nvidia Jetson Nano equipped with two fisheye cameras. The software has been evaluated considering the exercise biceps curl. The elbow angle has been measured by both MediaPipe and the motion capture system BTS (ground truth), and the resulting values have been compared to determine angle uncertainty, residual errors, and intra-subject and inter-subject repeatability. The uncertainty of the joints’ estimation and the quality of the image captured by the cameras reflect on the final uncertainty of the indicator over time, highlighting the areas of improvement for further development
A vision-based teleoperation system for robotic systems
Despite advances in robotic perception are increasing autonomous capabilities, human intelligence is still considered a necessity in unstructured or unpredictable environments. Hence, also according to the Industry 4.0 paradigm, humans and robots are encouraged to achieve mutual Human-Robot Interaction (HRI). HRI can be physical (pHRI) or not, depending on the assigned task. For example, when the robot is constrained in a dangerous environment or must handle hazardous materials, pHRI is not recommended. In these cases, robot teleoperation may be necessary. A teleoperation system concerns with the exploration and exploitation of spaces where the user presence is not allowed. Therefore, the operator needs to move the robot remotely. Although plenty of human-machine interfaces for teleoperation have been developed considering a mechanical device, vision-based interfaces do not require physical contact with external devices. This grants a more natural and intuitive interaction, which is reflected in task performance. Our proposed system is a novel robot teleoperation system that exploits RGB cameras, which are easy to use and commonly available on the market at a reduced price. A ROS-based framework has been developed to supply hand tracking and hand-gesture recognition features, exploiting the OpenPose software based on the Deep Learning framework Caffe. This, in combination with the ease of availability of an RGB camera, leads the framework to be strongly open-source-oriented and highly replicable on all ROS-based platforms. It is worth noting that the system does not include the Z-axis control in this first version. This is due to the high precision and sensitivity required to robustly control the third axis, a precision that 3D vision systems are not able to provide unless very expensive devices are adopted. Our aim is to further develop the system to include the third axis control in a future release
A gesture-based robot program building software
With the advent of intelligent systems, industrial workstations and working areas have undergone a revolution. The increased need for automation is satisfied using high-performance industrial robots in fully automated workstations. In the manufacturing industry, sophisticated tasks still require human intervention in completely manual workstations, even if at a slower production rate. To improve the efficiency of manual workstations, Collaborative Robots (Co-Bots) have been designed as part of the Industry 4.0 paradigm. These robots collaborate with humans in safe environments to support the workers in their tasks, thus achieving higher production rates compared to completely manual workstations. The key factor is that their adoption relieves humans from stressful and heavy operations, decreasing job-related health issues. The drawback of Co-Bots stands in their design: to work side-by-side with humans they must guarantee safety; thus, they have very strict limitations on their forces and velocities, which limits their efficiency, especially when performing non-trivial tasks. To overcome these limitations, our idea is to design Meta-Collaborative workstations (MCWs), where the robot can operate behind a safety cage, either physical or virtual, and the operator can interact with the robot, either industrial or Collaborative, by means of the same communication channel. Our proposed system has been developed to easily build robot programs purposely designed for MCWs, based on (i) the recognition of hand gestures (using a vision-based communication channel) and (ii) ROS to carry out communication with the robot
Engineering a C-Phase quantum gate: optical design and experimental realization
A two qubit quantum gate, namely the C-Phase, has been realized by exploiting
the longitudinal momentum (i.e. the optical path) degree of freedom of a single
photon. The experimental setup used to engineer this quantum gate represents an
advanced version of the high stability closed-loop interferometric setup
adopted to generate and characterize 2-photon 4-qubit Phased Dicke states. Some
experimental results, dealing with the characterization of multipartite
entanglement of the Phased Dicke states are also discussed in detail.Comment: accepted for publication on EPJ
Anisotropic suppression in nuclear collisions
The nuclear overlap zone in non-central relativistic heavy ion collisions is
azimuthally very asymmetric. By varying the angle between the axes of
deformation and the transverse direction of the pair momenta, the suppression
of and will oscillate in a characteristic way. Whereas the
average suppression is mostly sensitive to the early and high density stages of
the collision, the amplitude is more sensitive to the late stages. This effect
provides additional information on the suppression mechanisms such as
direct absorption on participating nucleons, comover absorption or formation of
a quark-gluon plasma. The behavior of the average suppression and its
amplitude with centrality of the collisions is discussed for SPS, RHIC and LHC
energies with and without a phase transition.Comment: Revised and extended version, new figure
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