The development of the Silurian trilobite Aulacopleura koninckii reconstructed by applying inferred growth and segmentation dynamics: A case study in paleo-evo-devo

Fossilized growth series provide rare glimpses into the development of ancient organisms, illustrating descriptively how size and shape changed through ontogeny. Occasionally fossil preservation is such that it is feasible to test alternative possibilities about how ancient development was regulated. Here we apply inferred developmental parameters pertaining to size, shape, and segmentation in the abundant and well-preserved 429 Myr old trilobite Aulacopleura koninckii that we have investigated previously to reconstruct the post-embryonic ontogeny of this ancient arthropod. Our published morphometric analyses associated with model testing have shown that: specification of the adult number of trunk segments (polymorphic in this species) was determined precociously in ontogeny; that growth regulation was targeted (i.e., compensatory), such that each developmental stage exhibited comparable variance in size and shape; and that growth gradients operating along the main body axis, both during juvenile and adult ontogeny, resulted from a form of growth control based on positional specification. While such developmental features are common among extant organisms, our results represent the oldest evidence for them within Metazoa. Herein, the novel reconstruction of the development of Aulacopleura koninckii permits visualization of patterns of relative and absolute growth and segmentation as never before possible for a fossilized arthropod ontogeny. By conducting morphometric analysis of appropriate data sets it is thus possible to move beyond descriptive ontogenetic studies and to address questions of high interest for evolutionary developmental biology using data from fossils, which can help elucidate both how developmental processes themselves evolve and how they affect the evolution of organismal body patterning. By extending similar analyses to other cases of exceptional preservation of fossilized ontogeny, we can anticipate beginning to realize the research program of “paleo-evo-devo.

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Review of Low pay and the minimum wage, Labour relations in the public service: developing countries, Public employment law: the role of the contract of employment in Australia and Britain, The system of industrial relations in New Zealan

The structure and spectra of molecular ions

PhD ThesisI give a review of the theory of the hydrogen molecular ion H2+ and its isotopomers D2+ and HD+ including the direct analytical solution and the standard adiabatic approximation. I discuss dissociation limits for homonuclear and heteronuclear species; the effect of an external electric field; non adiabatic calculations, relativistic and radiative effects; and spectroscopic measurements of H2+ and D2+ with a comparison of theoretical to experimental values. I give a detailed description of the fast ion-beam spectrometer as used for both laser-beam and microwave spectroscopy and describe the challenges involved in making high resolution spectroscopic measurements. An account is given of theory, experimental details and measurements of transition frequencies and intensities of the forbidden rotational transition (v = 19, N = 1) - (v = 19, N = 0) in the ground electronic state (X2Σg+, also represented as 1sσg) of H2+. Theory has predicted that the transition has measurable intensity due to the Fermi contact hyperfine interaction causing a breaking of electronic g/u symmetry resulting in the mixing of ortho-para states. The measurements were made in both single and double resonance using a fast ion beam/microwave spectrometer at a transition frequency of 14961.7 ± 1.1 MHz, in agreement with the theoretical prediction of 14960 ± 3 MHz. An account is also given of a further search that was conducted for a second forbidden rotational transition (v = 0, N = 1) - (v = 0, N = 0) in the first excited electronic state (2pσu) of H2+. A discussion is given on the possibility of making further observations of forbidden rotational transitions and the experimental difficulties involved; and of adapting the experimental techniques used in order to observe the recently discovered (v = 1, N = 0) in the first excited electronic state (2pσu) of H2+.The British Mass Spectrometry Society for funding my research with a John Beynon scholarship; to Seneca College of Applied Arts and Technology, Toronto, Canada for their assistance during the latter stages of my study

Performance evaluation of on-chip wavelength conversion based on InP/In1−x_{1-x}Gax_xAsy_yP1−y_{1-y} semiconductor waveguide platforms

We propose and design the high confinement InP/In1-xGaxAsyP1-y semiconductor waveguides and report the results of effective wavelength conversion based on this platform. Efficient confinement and mode field area fluctuation at different wavelength is analyzed to achieve the high nonlinear coefficient. The numerical results show that nearly zero phase-mismatch condition can be satisfied through dispersion tailoring of InP/In1-xGaxAsyP1-y waveguides, and the wavelength conversion ranging over 40 nm with the maximum conversion efficiency -26.3 dB is achieved for fixing pump power 100 mW. Meanwhile, the influences of the doping parameter y and pumping wavelength on the bandwidth and conversion efficiency are also discussed and optimized. It is indicated the excellent optical properties of the InP/In1-xGaxAsyP1-y waveguides and pave the way towards direct integration telecom band devices on stand semiconductor platforms.Comment: 21 page

Neisseria gonorrhoeae molecular typing for understanding sexual networks and antimicrobial resistance transmission: A systematic review.

OBJECTIVES: Neisseria gonorrhoeae (NG) is a significant global public health concern due to rising diagnoses rates and antimicrobial resistance. Molecular combined with epidemiological data have been used to understand the distribution and spread of NG, as well as relationships between cases in sexual networks, but the public health value gained from these studies is unclear. We conducted a systematic review to examine how molecular epidemiological studies have informed understanding of sexual networks and NG transmission, and subsequent public health interventions. METHODS: Five research databases were systematically searched up to 31st March 2017 for studies that used sequence-based DNA typing methods, including whole genome sequencing, and linked molecular data to patient-level epidemiological data. Data were extracted and summarised to identify common themes. RESULTS: Of the 49 studies included, 82% used NG Multi-antigen Sequence Typing. Gender and sexual orientation were commonly used to characterise sexual networks that were inferred using molecular clusters; clusters predominantly of one patient group often contained a small number of isolates from other patient groups. Suggested public health applications included using these data to target interventions at specific populations, confirm outbreaks, and inform partner management, but these were mainly untested. CONCLUSIONS: Combining molecular and epidemiological data has provided insight into sexual mixing patterns, and dissemination of NG, but few studies have applied these findings to design or evaluate public health interventions. Future studies should focus on the application of molecular epidemiology in public health practice to provide evidence for how to prevent and control NG

Dual-frequency sweeping light source based on four-wave mixing in silicon-on-insulator nano-waveguide

Four-wave mixing (FWM) is a well-known technique to achieve all-optical control wavelength conversion. We propose a well-designed silicon nano-waveguide based on silicon-on-insulator (SOI) to achieve FWM conversion. Particularly, the original signal light continuously sweeps along the C band, and the generated idler light is correspondingly sweeping as the original signal is swept. The wavelengths of the idler and signal lights are symmetric with respect to the pump light wavelength. Simulation and experimental results of the FWM conversion properties are well-matched. With the pump light filtered out, a dual-frequency continuously sweeping laser source is achieved, which could be applied in dual-frequency scanning interferometry to eliminate dynamic errors in practical use

Understanding the different challenges facing students in transitioning to university particularly with a focus on ethnicity

A positive and successful transition into University is crucial if students are to stay the course in higher education and experience successful outcomes. However, challenges exist in ensuring a connected transition from secondary and further education to higher education that is inclusive and supports the diversity in our current undergraduate student body. We set out to explore the diverse experiences that first year students report about their recent transition to a post-1992 University. We were particularly interested in how these experiences and challenges differed by ethnicity. This is incredibly important given the disparity, recognised in the sector, in the attainment of Black and Minority Ethnic (BME) students compared to their White counterparts and particularly pertinent that this trend reverses attainment patterns in secondary education. This paper summarises some of our key findings in determining the challenges facing students from different backgrounds in their transition to university. It argues that Universities will have to change their transition and wider offer to ensure that diverse students feel welcomed and develop a sense belonging in Higher Education in order for them to achieve successful outcomes