A Little Birdie Told Me About Agriculture: Best Practices and Future Uses of Twitter in Agriculutral Communications

Social media sites, such as Twitter, are impacting the ways businesses, organizations, and individuals use technology to connect with their audiences. Twitter enables users to connect with others through 140-character messages called “tweets” that answer the question, “What’s happening?” Twitter use has increased exponentially to more than five million active users but has a dropout rate of more than 50%. Numerous agricultural organizations have embraced the use of Twitter to promote their products and agriculture as a whole and to interact with audiences in a new way. This article addresses current Twitter use trends within agriculture and offers advice for practitioners

(E)-3-Bromo-N-(1,3-oxazolidin-2-yl­idene)benzamide

The five- and six-membered rings in the title compound, C10H9BrN2O2, are essentially coplanar. This is consistent with a highly conjugated system, as seen in the short N—C bond distances of 1.308 (6) and 1.317 (5) Å

Nanomechanical testing of freestanding polymer thin films

A new approach for tensile testing of freestanding polymer thin films has been developed to investigate nanomechanical phenomena with precise control of strain rate, environmental and in situ TEM imaging capabilities. Several techniques for mechanical testing of polymer thin films have been reported previously, but there is a lack of consensus regarding size-dependent mechanical properties1–3. The technique described here is derived from a nanomechanical tensile testing platform known as at Push-to-Pull (PTP) device (Figure 1) using a novel sample preparation approach. A free-standing specimen is placed across the tensile actuation gap of the PTP device such that it can be mounted at the end of a specialized TEM holder for quantitative in situ tensile testing or to a specialized mount was designed to enable PTP experiments to be performed using a stand-alone nanoindenter. With this adaptation, all of the capabilities of ex situ nanoindentation are accessible to PTP tensile testing; which includes environmental control (temperature and humidity), DMA, and a wide range of strain rates. Polystyrene was chosen as a model system for direct comparison with alternative testing techniques. While polystyrene is traditionally thought of as a brittle polymer at room temperature, our initial testing of thin sections has revealed extreme ductility (Figure 1). Ductility in polystyrene thin films has been previously reported in literature1–3, but only to elongations of less than 7% before fracture. Initial results using the PTP device have shown extreme ductility in polystyrene, with strains exceeding 100% without fracture. Our results appear to be independent of strain rate in the range tested; unlike the yield stress, which shows a strong strain-rate dependence. The origin of this nanomechanical pheno Please click Additional Files below to see the full abstract

Fast Grain Mapping with Sub-Nanometer Resolution Using 4D-STEM with Grain Classification by Principal Component Analysis and Non-Negative Matrix Factorization

High-throughput grain mapping with sub-nanometer spatial resolution is demonstrated using scanning nanobeam electron diffraction (also known as 4D scanning transmission electron microscopy, or 4D-STEM) combined with high-speed direct electron detection. An electron probe size down to 0.5 nm in diameter is implemented and the sample investigated is a gold-palladium nanoparticle catalyst. Computational analysis of the 4D-STEM data sets is performed using a disk registration algorithm to identify the diffraction peaks followed by feature learning to map the individual grains. Two unsupervised feature learning techniques are compared: Principal component analysis (PCA) and non-negative matrix factorization (NNMF). The characteristics of the PCA versus NNMF output are compared and the potential of the 4D-STEM approach for statistical analysis of grain orientations at high spatial resolution is discussed

A dynamic explanation for the origin of the western Mediterranean organic-rich layers

The eastern Mediterranean sapropels are among the most intensively investigated phenomena in the paleoceanographic record, but relatively little has been written regarding the origin of the equivalent of the sapropels in the western Mediterranean, the organic-rich layers (ORLs). ORLs are recognized as sediment layers containing enhanced total organic carbon that extend throughout the deep basins of the western Mediterranean and are associated with enhanced total barium concentration and a reduced diversity (dysoxic but not anoxic) benthic foraminiferal assemblage. Consequently, it has been suggested that ORLs represent periods of enhanced productivity coupled with reduced deep ventilation, presumably related to increased continental runoff, in close analogy to the sapropels. We demonstrate that despite their superficial similarity, the timing of the deposition of the most recent ORL in the Alboran Sea is different than that of the approximately coincident sapropel, indicating that there are important differences between their modes of formation. We go on to demonstrate, through physical arguments, that a likely explanation for the origin of the Alboran ORLs lies in the response of the western Mediterranean basin to a strong reduction in surface water density and a shoaling of the interface between intermediate and deep water during the deglacial period. Furthermore, we provide evidence that deep convection had already slowed by the time of Heinrich Event 1 and explore this event as a potential agent for preconditioning deep convection collapse. Important differences between Heinrich-like and deglacial-like influences are highlighted, giving new insights into the response of the western Mediterranean system to external forcing

Uniform Shock Waves in Disordered Granular Matter

The confining pressure $P$ is perhaps the most important parameter controlling the properties of granular matter. Strongly compressed granular media are, in many respects, simple solids in which elastic perturbations travel as ordinary phonons. However, the speed of sound in granular aggregates continuously decreases as the confining pressure decreases, completely vanishing at the jamming-unjamming transition. This anomalous behavior suggests that the transport of energy at low pressures should not be dominated by phonons. In this work we use simulations and theory to show how the response of granular systems becomes increasingly nonlinear as pressure decreases. In the low pressure regime the elastic energy is found to be mainly transported through nonlinear waves and shocks. We numerically characterize the propagation speed, shape, and stability of these shocks, and model the dependence of the shock speed on pressure and impact intensity by a simple analytical approach.Comment: 12 pages, 11 figure

(E)-Benzaldehyde O-{[3-(pyridin-3-yl)isoxazol-5-yl]meth­yl}oxime

The asymmetric unit of the title compound, C16H13N3O2, contains two independent mol­ecules in which the pyridine and benzene rings form dihedral angles of 81.7 (2) and 79.8 (2)°, indicating the twist in the mol­ecules. In the crystal, weak C—H⋯N inter­actions link mol­ecules into chains along [100]