Close Cassini flybys of Saturn’s ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus

Saturn’s main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. Data on the moons’ morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. We find that the optical properties of the moons’ surfaces are determined by two competing processes: contamination by a red material formed in Saturn’s main ring system and accretion of bright icy particles or water vapor from volcanic plumes originating on the moon Enceladus.

Volumetric comparison of autogenous bone and tissue-engineered bone replacement materials in alveolar cleft repair: a systematic review and meta-analysis

The goal of reconstruction of the alveolar cleft in patients with cleft lip and palate is to improve the quality of tissue, the structural stability, and increase the volume of bone. This study is a systematic review with meta-analysis of volumetric bony filling using autogenous bone and various tissue-engineered bone substitutes. We made an electronic search on MEDLINE, EMBASE, SCOPUS, WEB OF SCIENCE, "grey" publications (materials and research produced by organisations outside traditional channels for commercial or academic publishing and distribution), and relevant cross references according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies that reported the outcomes of volumetric grafting were included in the meta-analysis. Of 1276 studies, 26 were included in the meta-analysis. Pooled analysis of 25 studies that used autogenous bone showed a significant reduction in the volume of the cleft equivalent to 62.0% bone fill (95% CI 54.3 to 69.6), in contrast to 10 studies that used a tissue-engineered material and reported bone filling of 68.7% (95% CI 54.5 to 82.8). The estimated sizes of pooled effects across studies showed that there was no significant difference between the two major intervention groups (p value 0.901). Our statistical analysis showed that autogenous bone grafts did not differ significantly from tissue-engineered materials in their ability to fill clefts. Systematic review registration: International Prospective Register of Systematic Reviews, PROSPERO (CRD42017065045).

Enhanced energy transfer in heterogeneous nanocrystals for near infrared upconversion photocurrent generation

The key to produce inorganic heterogeneous nanostructures, and to integrate multiple functionalities, is to enhance or at least retain the functionalities of different components of materials. However, this ideal scenario is often deteriorated at the interface of the heterogeneous nanostructures due to lattice mismatches, resulting in downgraded performance in most hybrid nanomaterials. Here, we report that there is a narrow window in controlling temperature in a Lewis acid-base reaction process to facilitate epitaxial alignment during the synthesis of hybrid nanomaterials. We demonstrate a perfectly fused NaYF₄:Yb,Tm@ZnO heterogeneous nanostructure, in which the semiconductor ZnO shell can be epitaxially grown onto lanthanide-doped upconversion nanoparticles. By achieving a matched crystal lattice, the interface defects and crystalline grain boundaries are minimized to enable more efficient energy transfer from the upconversion nanoparticles to the semiconductor, resulting in both enhanced upconversion luminescence intensity and superior photoelectrochemical properties. This strategy provides an outstanding approach to endow lanthanide-doped upconversion nanoparticles with versatile properties.

Increased production and cover in a variable native pasture following intensive grazing management

Native pastures account for approximately half the grazing area of the high-rainfall zone of southern Australia and the appropriate intensity of grazing management to improve pasture production and to sustain native species composition is still debated. This paper describes differences in pasture herbage mass, ground cover and composition for a native pasture managed under three distinct grazing-management intensities (1-, 4- and 20-paddock grazing systems). Grazing-management treatments were implemented for 4 years across a variable landscape and the interaction of grazing management and landscape position (high-, medium- and low-production zones) were examined. Increasing the intensity of grazing management (number of paddocks in the grazing system) resulted in higher standing, green and litter herbage mass and ground cover of pastures, with differences most pronounced in the high-production zone where selective grazing was regulated with grazing management. Landscape position largely influenced pasture composition, with higher pasture production and more productive species (e.g. Microlaena stipoides, Lolium rigidum and legumes) in the high-production zone. Small increases in the DM of native perennial grasses and lower levels of legumes and broad-leaf weeds developed in the 20-paddock system compared with grazing in 1- and 4-paddock systems. Net pasture growth was higher in the 20-paddock than 1-paddock treatment during spring in the last 2 years of the experiment, resulting in 21% (1.6 t DM/ha) more herbage mass accumulated over the year. While productivity and cover were higher under intensive rotational grazing, grazing management had little influence on pasture composition. A stable perennial pasture (>70% perennial grasses) stocking rates that were not degrading and the strong influence of landscape on pasture composition limited management influences. Practically, the results indicated that, at the same stocking rate, increasing the intensity of grazing management can increase the average pasture herbage mass, ground cover and pasture growth by more evenly distributing grazing.

Designing a grazing-system experiment for variable native pastures and flexible lamb-production systems

Grazing-system experiments address complex interactions among animals, pastures, soils, climate and management. As part of the national EverGraze program, a grazing-system experiment was designed to determine how the intensity of grazing management, from continuous grazing (P01) to flexible 4- and 20-paddock rotational systems (P04 and P20), influences the profitability and sustainability of a Merino ewe, terminal sire, lamb production system grazed on heterogeneous native pastures. When implementing such an experiment, it is important to understand and characterise landscape variability, and include this in the design of the experiment. A second challenge for grazing-system research is to operate experimental systems with sufficient flexibility to adequately represent commercial production systems and maintain even utilisation across treatments. The present paper addresses the following two issues: (1) the process used to characterise the potential productivity of variable native pastures and the results of this characterisation; and (2) the development of flexible systems that adequately represent commercial production within an experiment. This was undertaken with input from a project-steering committee called the EverGraze Regional Group, comprising producers, extension staff and private consultants. Prior to the commencement, the site was mapped into three production zones, namely, high (HPZ), medium (MPZ) and low (LPZ), by visually estimating green herbage mass in late spring and marking boundaries between zones with a GPS. The production zones represented differences in soil properties (gravel, pH and available P) and pasture composition, and were used to balance potential production among plots within the same replication. Grazing-system options were evaluated using the sustainable grazing systems pasture model to help choose an appropriate starting stocking rate. The initial stocking rate chosen for the spring-lambing systems was 5.4 ewes/ha. The modelling predicted large variations in feed availability and quality over summer among years; flexible management criteria were therefore developed, including variable sale time for lambs, to utilise the greater feed supply in better seasons. Minimum-pasture benchmarks (>0.8 t DM/ha standing herbage mass and >80% ground cover) and variable green herbage-mass targets were designed to sustain high levels of livestock production and prevent pasture degradation. Criteria for adjusting ewe numbers were developed, but were constrained to pre-joining (March), scanning (July) and post-weaning (December), being consistent with commercial practices. The experiment incorporated flexible management rules as these were considered integral to the successful management of commercial grazing systems.

Depression, marijuana use and early-onset marijuana use conferred unique effects on neural connectivity and cognition

OBJECTIVE

Marijuana (MJ) use is common. Research shows risks for psychiatric illnesses, including major depressive disorder (MDD) and cognitive deficits with MJ use, particularly early-onset use. We investigated cognitive function, functional connectivity, and genetic risk with MDD alone and combined with MJ use, and differences between early-vs. late-onset/non-MJ use in youth.

METHOD

A total of 74 youth in four groups were studied: healthy control, MDD, frequent MJ use and current/past MDD plus frequent MJ use. Psychiatric symptoms, cognitive performance and demographics were measured. Default mode network (DMN) brain connectivity was determined. Risk alleles in six genes of interest were evaluated.

RESULTS

DMN differences among groups in reward-processing and motor control regions were found; the effects of MJ use and MDD were distinct. Early-onset MJ use was associated with lower IQ and hyperconnectivity within areas of the DMN. Early-onset MJ use was associated with the BDNF risk allele.

CONCLUSIONS

Cognitive deficits linked with early-onset MJ use were present within several years after MJ use began and may result from, predispose to, or share a common cause with early-onset MJ use. The DMN was affected by MDD, MJ and their combination, as well as by early-onset MJ use. BDNF carrier state may predispose to early-onset MJ use.