Pronounced and prevalent intersexuality does not impede the ‘Demon Shrimp’ invasion

Crustacean intersexuality is widespread and often linked to infection by sex-distorting parasites. However, unlike vertebrate intersexuality, its association with sexual dysfunction is unclear and remains a matter of debate. The ‘Demon Shrimp,’ Dikerogammarus haemobaphes, an amphipod that has invaded continental waterways, has recently become widespread in Britain. Intersexuality has been noted in D. haemobaphes but not investigated further. We hypothesise that a successful invasive population should not display a high prevalence of intersexuality if this condition represents a truly dysfunctional phenotype. In addition, experiments have indicated that particular parasite burdens in amphipods may facilitate invasions. The rapid and ongoing invasion of British waterways represents an opportunity to determine whether these hypotheses are consistent with field observations. This study investigates the parasites and sexual phenotypes of D. haemobaphes in British waterways, characterising parasite burdens using molecular screening, and makes comparisons with the threatened Gammarus pulex natives. We reveal that invasive and native populations have distinct parasitic profiles, suggesting the loss of G. pulex may have parasite-mediated eco-system impacts. Furthermore, the parasite burdens are consistent with those previously proposed to facilitate biological invasions. Our study also indicates that while no intersexuality occurs in the native G. pulex, approximately 50% of D. haemobaphes males present pronounced intersexuality associated with infection by the microsporidian Dictyocoela berillonum. This unambiguously successful invasive population presents, to our knowledge, the highest reported prevalence of male intersexuality. This is the clearest evidence to date that such intersexuality does not represent a form of debilitating sexual dysfunction that negatively impacts amphipod populations

Motion in the north Iceland volcanic rift zone accommodated by bookshelf faulting

Along mid-ocean ridges the extending crust is segmented1 on length scales of 10–1,000 km. Where rift segments are offset from one another, motion between segments is accommodated by transform faults that are oriented orthogonally to the main rift axis. Where segments overlap, non-transform offsets with a variety of geometries2 accommodate shear motions. Here we use micro-seismic data to analyse the geometries of faults at two overlapping rift segments exposed on land in north Iceland. Between the rift segments, we identify a series of faults that are aligned sub-parallel to the orientation of the main rift. These faults slip through left-lateral strike-slip motion. Yet, movement between the overlapping rift segments is through right-lateral motion. Together, these motions induce a clockwise rotation of the faults and intervening crustal blocks in a motion that is consistent with a bookshelf-faulting mechanism, named after its resemblance to a tilting row of books on a shelf3. The faults probably reactivated existing crustal weaknesses, such as dyke intrusions, that were originally oriented parallel to the main rift and have since rotated about 15° clockwise. Reactivation of pre-existing, rift-parallel weaknesses contrasts with typical mid-ocean ridge transform faults and is an important illustration of a non-transform offset accommodating shear motion between overlapping rift segments

Review of the evidence base in relation to early childhood approaches to support children in highly disadvantaged communities for the Children’s Ground Project

The Children’s Ground project aims to develop a place-based approach to support children and their families in highly disadvantaged communities. The project approach is informed by research and evidence, recognising the multiple and multi-level influences on children’s development and the need to support the role of communities in improving outcomes for children. The review of the evidence base, undertaken by the Centre for Community Child Health in collaboration with the Royal Children’s Hospital Education Institute, begins by outlining the changing social and environmental conditions and the influence of these changes on vulnerable children and families. The report then discusses actions undertaken to address these challenges and the reasons why these actions have failed. Next, key factors enabling optimal outcomes for children and contemporary Australian and international evidence-based interventions and approaches that support vulnerable children are examined. The review concludes by summarising the research on the financial and social costs of doing nothing to intervene and improve outcomes for children. In summary, the review endorses the development of a place-based approach with a number of key strategies that simultaneously address families’ immediate needs for support (the foreground factors) and the broader conditions under which families are raising young children (the background factors). The approach needs to promote wrap around, integrated services that are responsive to and driven by the community. Focus must also be given to how services are delivered rather than what is delivered. In order to implement the approach, it is critical that a robust governance structure or entity capable of coordinating and supporting the many stakeholders and services involved is established and a long-term financial and policy commitment is made. Key messages encapsulating broad themes from the literature, supported by concluding statements, have been developed to enable clear communication to a variety of audiences.&nbsp

Thyristor-Bypassed Sub-Module Power-Groups for Achieving High-Efficiency, DC Fault Tolerant Multilevel VSCs

Achieving DC fault tolerance in modular multilevel converters requires the use of a significant number of Sub-Modules (SMs) which are capable of generating a negative voltage. This results in an increase in the number of semiconductor devices in the current path, increasing converter conduction losses. This paper introduces a thyristor augmented multilevel structure called a Power-Group (PG), which replaces the stacks of SMs in modular converters. Each PG is formed out of a series stack of SMs with a parallel force-commutated thyristor branch, which is used during normal operation as a low loss bypass path in order to achieve significant reduction in overall losses. The PG also offers negative voltage capability and so can be used to construct high efficiency DC fault tolerant converters. Methods of achieving the turn-on and turn-off of the thyristors by using voltages generated by the parallel stack of SMs within each PG are presented, while keeping both the required size of the commutation inductor, and the thyristor turn-off losses low. Efficiency estimates indicate that this concept could result in converter topologies with power-losses as low as 0.3% rated power, whilst retaining high quality current waveforms and achieving tolerance to both AC and DC faults

Dimensioning and Modulation Index Selection for the Hybrid Modular Multilevel Converter

The Hybrid MMC, comprising a mixture of fullbridge and half-bridge sub-modules, provides tolerance to DC faults without compromising the efficiency of the converter to a large extent. The inclusion of full-bridges creates a new freedom over the choice of ratio of AC to DC voltage at which the converter is operated, with resulting impact on the converter’s internal voltage, current and energy deviation waveforms, all of which impact the design of the converter. A design method accounting for this, and allowing the required level of derating of nominal sub-module voltage and up-rating of stack voltage capability to ensure correct operation at the extremes of the operating envelope is presented. A mechanism is identified for balancing the peak voltage that the full-bridge and halfbridge sub-modules experience over a cycle. Comparisons are made between converters designed to block DC side faults and converters that also add STATCOM capability. Results indicate that operating at a modulation index of 1.2 gives a good compromise between reduced power losses and additional required sub-modules and semiconductor devices in the converter. The design method is verified against simulation results and the operation of the converter at the proposed modulation index is demonstrated at laboratory-scale

An Analysis of the Environments of FU Orionis Objects with Herschel

We present Herschel-HIFI, SPIRE, and PACS 50-670 {\mu}m imaging and spectroscopy of six FU Orionis-type objects and candidates (FU Orionis, V1735 Cyg, V1515 Cyg, V1057 Cyg, V1331 Cyg, and HBC 722), ranging in outburst date from 1936-2010, from the "FOOSH" (FU Orionis Objects Surveyed with Herschel) program, as well as ancillary results from Spitzer-IRS and the Caltech Submillimeter Observatory. In their system properties (Lbol, Tbol, line emission), we find that FUors are in a variety of evolutionary states. Additionally, some FUors have features of both Class I and II sources: warm continuum consistent with Class II sources, but rotational line emission typical of Class I, far higher than Class II sources of similar mass/luminosity. Combining several classification techniques, we find an evolutionary sequence consistent with previous mid-IR indicators. We detect [O I] in every source at luminosities consistent with Class 0/I protostars, much greater than in Class II disks. We detect transitions of 13CO (J_up of 5 to 8) around two sources (V1735 Cyg and HBC 722) but attribute them to nearby protostars. Of the remaining sources, three (FU Ori, V1515 Cyg, and V1331 Cyg) exhibit only low-lying CO, but one (V1057 Cyg) shows CO up to J = 23 - 22 and evidence for H2O and OH emission, at strengths typical of protostars rather than T Tauri stars. Rotational temperatures for "cool" CO components range from 20-81 K, for ~ 10^50 total CO molecules. We detect [C I] and [N II] primarily as diffuse emission.Comment: 31 pages, 15 figures; accepted to Ap