THE STRUCTURE, LIMITS, AND DRIVERS OF DAPHNID DIVERSITY

In 1961 Hutchinson proposed the “Paradox of the Plankton” questioning how sympatric planktonic species can coexist for long periods of time while seemingly avoiding the competitive exclusion principle. As this ‘paradox’ became a focus of inquiry, one researcher conducted a 2-year study (1961-1962; Tappa 1965) on Aziscohos Lake Daphnia to address the question. While the study did not solve the enigma, it provided a detailed record of the dynamics and interactions of six coexisting species. Aziscohos Lake and its zooplankton have not been studied since. This study revisits the ‘paradox of the plankton’ by establishing the dynamics of extant Daphnid populations within Aziscohos Lake. Analysis of plankton tows indicate that five species (D. catawba, D. ambigua, D. g. mendotae, D.retrocurva, D. dubia) from Tappa’s study are still present in addition to three species (D. rosea, D. schødleri, D. parvula) recorded for the first time in Aziscohos Lake. This composition is unusually high given that the typical lake has between 1 and 3 species of Daphnia. It is proposed here that a seasonal compression of the littoral region from drawdowns of Aziscohos Lake is forcing littoral species into direct competition and overlap with pelagic species. This results in a higher species richness from a pelagic sample than the average lake that does not undergo such drastic lake level fluctuations. Further research of the littoral zone of Aziscohos Lake is recommended, as all previous studies have focused on the pelagic zone

The Late Prehistory of the Alutiiq People: Culture Change on the Kodiak Archipelago From 1200-1750 A.D.

Esta tesis se centra en un estudio experimental sobre la adquisición de las obstruyentes del chino y del español como L3 las oclusivas, las africadas y las fricativas. En este estudio, participaron dos grupos de hablantes: un grupo de nativos chinos cuya L2 es el inglés y cuya L3 es el español y un grupo de nativos españoles cuya L2 es el inglés y cuya L3 es el chino. Los dos grupos constituyen el grupo de análisis de su L3, al mismo tiempo, sirven de grupo de control de su L1. Ambos grupos de informantes participaron en una serie de experimentos, tanto de producción como de percepción. En la tarea de producción, se leyeron textos fonéticamente equilibrados para cada lengua y, en la de percepción, se llevó a cabo una tarea de identificación de los fonemas que presentaban alguna dificultad en la producción. De esta forma, se comprobó si en la adquisición de las obstruyentes el proceso de producción precedía al de percepción. Para analizar los datos de producción, se utilizaron dos métodos diferentes: la categorización de errores y el análisis acústico de los datos. Los resultados obtenidos señalan un comportamiento diferente en función del tipo de análisis, de la categoría, de la lengua y del tipo de tarea. En primer lugar, la sistematización de los errores requiere un análisis acústico para categorizar las realizaciones que produce el hablante. Algunas realizaciones producidas por el grupo de aprendices, que han sido categorizadas como correctas, muestran en un análisis acústico posterior características diferentes a las del grupo de nativos. En segundo lugar, categorías diferentes de sonidos presentan distintos resultados de adquisición; por lo tanto, no se pueden tratar de la misma forma. El chino y el español, aunque cuentan con algunos fonemas similares, no poseen exactamente las mismas características, lo que da lugar a una reflexión sobre el concepto de fonemas similares. La producción y la percepción también muestran resultados diferentes, indicando una complejidad en la relación de ambos procesos. Por último, los resultados obtenidos nos ayudan a interpretar mejor las interacciones entre los sistemas fónicos de un hablante y entender las influencias interlingüísticas que se pueden dar entre las lenguas que conoce un mismo hablante.This thesis aims at investigating the acquisition of Spanish and Mandarin Chinese by L3 learners. The sounds under investigation are the obstruents, namely, stops, affricates and fricatives. Two groups of participants were involved in the study: L1 Mandarin Chinese, L2 English, and L3 Spanish speakers; L1 Spanish, L2 English and L3 Mandarin Chinese speakers. The participants took part in a series of perception and production tasks for data elicitation in Chinese and Spanish. The production tasks involve in reading phonetically balanced passages. Based on their performance in production, perceptual tests were designed on those sounds which presented more difficulty. For data analysis, production data were categorized based on acoustic observation in the spectrogram and only those production which were categorized as authentic production were submitted for acoustic comparison. Later, perception tasks were performed on the sounds where more mistakes were observed. The results show that different tasks, languages, and sounds may have an effect on participants' performance. It also seems that categorization is not enough to evaluate the learners' production, since the sounds which were categorized as correct production show different acoustic performance from that of the native speakers. Secondly, not all sounds show the same degree of difficulty. Some sounds were produced and perceived more accurately than others. Thus, it may be more adequate to treat them separately during the investigation. Moreover, even though Mandarin and Spanish share some similar phonemes, they may differ acoustically. The relationship between production and perception seems to be complex and no unique pattern has been observed. All the findings seem to suggest that the cross-linguistic influence may be observed in these learners. It takes different directions and it can either facilitate or hinder learners' acquisition. Learners' L3 seems to be influenced by their L1 and L2. There also seems to be a regressive transfer on their L1

Mineralogy of apophyllite-prehnite veins from skarns near Bludov

Mineralogy of the new find of apophyllite-prehnite vein from Ca-skarn in quarry at Bludov near Šumperk was studied, using microscopy, WDX-analysis and X-ray powder diffraction. Up-to 5 cm thick vein is composed of dominant green prehnite and younger white apophyllite, both in coarsegrained aggregates. Accessory minerals of the vein are the oldest hydrothermal epidote, young calcite, and relicts of grossular (with 30–43 % andradite) and pyroxene from host skarn. Prehnite vein changes into quartz vein. Apophyllite is practically pure end-member (97–99 % fluorapophyllite) and according to X-ray analysis is not albitized. Higher contents of F (0.04–1.46 wt. %) are typical for all vein minerals (prehnite, epidote) and relics of garnet and diopside, which indicates high activity of F in fl uids. More generation of prehnite were identified. The studied apophyllite-prehnite vein of the „Alpine type“ crystallized from low-temperature hydrothermal solutions of local origin.Mineralogy of the new find of apophyllite-prehnite vein from Ca-skarn in quarry at Bludov near Šumperk was studied, using microscopy, WDX-analysis and X-ray powder diffraction. Up-to 5 cm thick vein is composed of dominant green prehnite and younger white apophyllite, both in coarsegrained aggregates. Accessory minerals of the vein are the oldest hydrothermal epidote, young calcite, and relicts of grossular (with 30–43 % andradite) and pyroxene from host skarn. Prehnite vein changes into quartz vein. Apophyllite is practically pure end-member (97–99 % fluorapophyllite) and according to X-ray analysis is not albitized. Higher contents of F (0.04–1.46 wt. %) are typical for all vein minerals (prehnite, epidote) and relics of garnet and diopside, which indicates high activity of F in fl uids. More generation of prehnite were identified. The studied apophyllite-prehnite vein of the „Alpine type“ crystallized from low-temperature hydrothermal solutions of local origin

Dating and Digging Stratified Archaeology in Circumpolar North America : A View from Nunalleq, Southwestern Alaska

The results presented in this paper were funded by a NERC Radiocarbon Facility grant (NRCF 1917.0415), while the wider project is funded by the Arts and Humanities Research Council (AH/K006029/1). The authors wish to thank all the members of the excavation crew from the 2014 field season for their hard work in the challenging weather conditions of southwest Alaska – without their attention to detail this study would not have been possible. Additional thanks are also due to Qanirtuuq Incorporated for logistical support and warm hospitality in Quinhagak. We also wish to thank Kevin Edwards and Kate Britton, who read an earlier draft of this paper, and three anonymous reviewers for highly constructive criticism that helped us to improve the final manuscript.Peer reviewedPublisher PD

Reconstructing caribou seasonal biogeography in Little Ice Age (late Holocene) Western Alaska using intra-tooth strontium and oxygen isotope analysis

Acknowledgements This work was funded by an Arts and Humanities Research Council (AH/K006029/1) grant awarded to Rick Knecht, Kate Britton and Charlotta Hillerdal (Aberdeen). The onsite collection of samples was carried out by staff and students from the University of Aberdeen, volunteer excavators and the residents of Quinhagak. We also thank the Qanirtuuq Incorporated, Quinhagak, Alaska, and the people of Quinhagak for logistical and planning support for fieldwork and sampling permissions. Special thanks for Warren Jones and Qanirtuuq Incorporated (especially Michael Smith and Lynn Church), and to all Nunalleq project team members, particularly Edouard Masson-MacLean and Paul Ledger (Aberdeen). Thanks also to Alison Harris (Stockholm/York), Rebecca Lam and Sherri Strong (Memorial University) and Michael Maus (Johannes-Gutenberg Universität, Mainz) for methodological and technical assistance. Thank you to Dominic Demma (Alaska Department of Fish and Game) for providing information on the Mulchatna herd, to Edouard Masson-MacLean for comments on an earlier draft of this manuscript, and to the guest editors for inviting us to contribute to this special issue. Finally, the authors would like to thank the reviewers for their valuable and constructive comments on this manuscript.Peer reviewedPublisher PD

Development of life satisfaction in young physicians: results of the prospective SwissMedCareer Study

Purpose: The objectives of the study were to investigate the gender-related development of life satisfaction in young physicians over an 8-year period of residency, to compare it with a representative sample, and to analyze the relationships between both person- and health-related factors and life satisfaction. Methods: A prospective study was carried out including five measurement points among a cohort of 337 Swiss physicians. Measurements include domain-specific life satisfaction (FLZM), sense of coherence (SOC-13), anxiety and depression (HADS-D), chronic stress (TICS) and socio-demographic variables. Data were analyzed with multivariate procedures. Results: Life satisfaction in physicians of both genders is lower compared to a representative sample. Over the 8-year period of residency, the course of life satisfaction seems to be rather unstable and domain-specific. Female physicians are more satisfied with life than their male counterparts. Depressive symptoms and stress experience are highly negatively associated with life satisfaction in multivariate analysis. Conclusions: To study the development of life satisfaction over time, it is more appropriate to use a domain-specific life satisfaction questionnaire than a total score. Furthermore, it is a matter of concern that—compared to a representative sample—physicians in residency show lower life satisfaction at all measurement points. Depressive symptoms and chronic stress are found to diminish life satisfaction. This could keep some physicians from staying in the medical profession. Senior physicians should be aware of the negative impact of chronic stress on life satisfactio

Reduction of hydraulic losses in a piston pump

The hydraulic losses are the decrease in energy of the fluid due to vortex formation, friction between the fluid and the pipe, changing the flow of fluid. The decrease in energy of the fluid, in turn, leads to the following consequences: decrease efficiency, increase energy consumption and decrease cavitation stock pump. The main danger in a piston pump is to reduce cavitation stock. This leads to boiling of water by pressure reduction and rapid destruction the flow part of the pump

Three Generations Under One Roof? Bayesian Modeling of Radiocarbon Data from Nunalleq, Yukon-Kuskokwim Delta, Alaska

Acknowledgments. This research was funded through an Arts and Humanities Research Council grant (AH/K006029/1) awarded to Drs. Rick Knecht, Charlotta Hillerdal, and Kate Britton, and two NERC Radiocarbon Facility grants (NF/2015/1/6 and NF/2015/2/3) awarded to Drs. Rick Knecht and Paul Ledger. Véronique Forbes received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement number 703322. Excavations at Nunalleq have also benefited from the support of the local community who have made us all feel at home in Quinhagak. In particular, we wish to thank Qanirtuuq Incorporated and Warren Jones for logistical support and their consistently warm hospitality. Thanks also to Philip Ashlock who took the aerial image presented in Figure 3. We also wish to acknowledge the contribution of all of the students and researchers who have excavated at Nunalleq between 2009 and 2015. Without their hard work and dedication, in sometimes challenging conditions, this article would not have been possible. Finally, we wish to thank three anonymous reviewers and Robert Kelly for constructive criticism that has helped improved this manuscript. Permission for excavations at Nunalleq was granted by Qanirtuuq Incorporated.Peer reviewedPublisher PD