We report polarization properties for eight narrowband bursts from FRB 121102 that have been re-detected in a high-frequency (4-8 GHz) Breakthrough Listen observation with the Green Bank Telescope, ...originally taken on 2017 August 26. The bursts were found to exhibit nearly 100% linear polarization, Faraday rotation measures (RM) bordering 9.3\(\times\)10\(^4\) rad-m\(^{-2}\), and stable polarization position angles (PA), all of which agree with burst properties previously reported for FRB 121102 at the same epoch. We confirm that these detections are indeed physical bursts with limited spectral occupancies and further support the use of sub-banded search techniques in FRB detection.
Bioinspired spring origami Faber, Jakob A; Arrieta, Andres F; Studart, André R
Science,
03/2018, Letnik:
359, Številka:
6382
Journal Article
Recenzirano
Odprti dostop
Origami enables folding of objects into a variety of shapes in arts, engineering, and biological systems. In contrast to well-known paper-folded objects, the wing of the earwig has an exquisite ...natural folding system that cannot be sufficiently described by current origami models. Such an unusual biological system displays incompatible folding patterns, remains open by a bistable locking mechanism during flight, and self-folds rapidly without muscular actuation. We show that these notable functionalities arise from the protein-rich joints of the earwig wing, which work as extensional and rotational springs between facets. Inspired by this biological wing, we establish a spring origami model that broadens the folding design space of traditional origami and allows for the fabrication of precisely tunable, four-dimensional-printed objects with programmable bioinspired morphing functionalities.
Soft actuation allows robots to interact safely with humans, other machines, and their surroundings. Full exploitation of the potential of soft actuators has, however, been hindered by the lack of ...simple manufacturing routes to generate multimaterial parts with intricate shapes and architectures. Here, we report a 3D printing platform for the seamless digital fabrication of pneumatic silicone actuators exhibiting programmable bioinspired architectures and motions. The actuators comprise an elastomeric body whose surface is decorated with reinforcing stripes at a well-defined lead angle. Similar to the fibrous architectures found in muscular hydrostats, the lead angle can be altered to achieve elongation, contraction, or twisting motions. Using a quantitative model based on lamination theory, we establish design principles for the digital fabrication of silicone-based soft actuators whose functional response is programmed within the material's properties and architecture. Exploring such programmability enables 3D printing of a broad range of soft morphing structures.
The properties of conventional materials result from the arrangement of and the interaction between atoms at the nanoscale. Metamaterials have shifted this paradigm by offering property control ...through structural design at the mesoscale, thus broadening the design space beyond the limits of traditional materials. A family of mechanical metamaterials consisting of soft sheets featuring a patterned array of reconfigurable bistable domes is reported here. The domes in this metamaterial architecture can be reversibly inverted at the local scale to generate programmable multistable shapes and tunable mechanical responses at the global scale. By 3D printing a robotic gripper with energy‐storing skin and a structure that can memorize and compute spatially‐distributed mechanical signals, it is shown that these metamaterials are an attractive platform for novel mechanologic concepts and open new design opportunities for structures used in robotics, architecture, and biomedical applications.
A dome‐patterned mechanical metamaterial displaying extraordinary property adaptation, shape‐shifting, and intrinsic mechanologic is presented. This displays an exponentially large and unique set of programmed global states that can be accessed by specific spatiotemporal deformations. This programmability is applied to designing soft robotic grippers that actuate without external energy sources and the collocation of memory and computation as a material property.
An epidemic of foodborne infection with
Escherichia coli
associated with a high rate of the hemolytic–uremic syndrome and caused by a novel
E. coli
strain (O104:H4) recently occurred in Germany. This ...final report updates epidemiologic, clinical, and microbiologic information.
On May 19, 2011, the Robert Koch Institute, Germany's national-level public health authority, was informed about a cluster of three cases of the hemolytic–uremic syndrome in children admitted on the same day to the university hospital in the city of Hamburg. On May 20, a team from the Robert Koch Institute arrived in Hamburg to assist with the public health investigation. It quickly became clear that the case numbers were continuing to rise, that there were also cases in adults, and that other areas of Germany, especially northern Germany, were also affected. An investigation of the outbreak involving all levels . . .
Leaf dark respiratory CO2‐release (RD) is, according to some literature, dependent on the rate of leaf transpiration. If this is true, then at a given vapor pressure deficit, the leaf stomatal ...conductance (gs) will be expected to be a controlling factor of measured RD at any given time. We artificially lowered leaf gs by applying abscisic acid (ABA). Although leaf RD generally covaried temporally with gs, artificially lowering gs by applying ABA does not affect the measured leaf RD. These results indicate that observed diel fluctuations in gs are not directly influencing the measured leaf RD, thereby simplifying both future studies and the interpretation of past studies of the underlying environmental‐ and physiological drivers of temporal variation in leaf RD.
The existence of gender disparities in academia is well documented. Many explanations have been proposed and productivity is one of the most used variables to explain a possible correlation between ...gender and differences in academic rank or leadership positions. The literature on the existence of a productivity gender gap is inconclusive which may due to the variety of study designs. This article presents the results of a longitudinal bibliometric study of health science researchers controlling for sub-disciplinary affiliation, education, year of enrollment and age. The productivity and impact of the researchers are analyzed during a 16-year period. We find no or little difference in productivity or impact among the group of health sciences researchers from the time of enrollment in the Ph.D. program and 10 years beyond, and women outperform men in some cases. There are negligible differences in productivity and impact prior to enrollment. The implications of the findings are discussed.
Conventional methods of programmed shape change in polymers are one-way and one-time only. We introduce a new method of combining a bioinspired, hierarchical architecture with the pre-strain ...generated by extrusion-based 3D printing to encode multiple permanent shapes in thermoplastic polymer shell structures. At high temperature, these structures are multistable and can snap repeatedly between all encoded permanent shapes without reprogramming. At low temperature, the structures are monostable with increased stiffness; the multistability can be switched on and off via temperature. Characterization studies are performed to determine how to control the level of pre-strain and the deflection behavior of the structure to enable finite element modeling for analysis and design. This pre-straining technique may be thought of as a virtual mold: printed structures are initially flat but have multiple permanent shapes encoded. Taking advantage of the geometric freedom of 3D printing, complex geometries, and pre-strain fields may be used to create highly tailored snapping structures. Thermoplastic filaments with added particles may be used to impart additional multifunctionality to the structures, such as magnetic responsiveness, to enable remote actuation. These switchable multistable structures have potential applications in fields including robotics, aerospace, and smart buildings.
Display omitted
•Multiple permanent shapes are encoded in shape memory polymer structures.•Printed polymer structures have reversible, repeatable morphing without reprogramming.•Multistability can be repeatedly switched on and off with temperature.•3D printing is used to create bioinspired hierarchical architectures.•Amount of pre-strain is controlled through print settings.
Leaf dark respiratory CO
-release (R
) is, according to some literature, dependent on the rate of leaf transpiration. If this is true, then at a given vapor pressure deficit, the leaf stomatal ...conductance (g
) will be expected to be a controlling factor of measured R
at any given time. We artificially lowered leaf g
by applying abscisic acid (ABA). Although leaf R
generally covaried temporally with g
, artificially lowering g
by applying ABA does not affect the measured leaf R
. These results indicate that observed diel fluctuations in g
are not directly influencing the measured leaf R
, thereby simplifying both future studies and the interpretation of past studies of the underlying environmental- and physiological drivers of temporal variation in leaf R
.
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