Ice-ocean-atmosphere interactions in the Arctic Seas

Arctic ice masses have rapidly lost mass during the past two decades, coincident with marked climatic and oceanic change. Accelerated ice discharge through marine-terminating outlet glaciers has been a primary contributor to deficits. However, substantial uncertainty exists over the factors controlling Arctic outlet glacier dynamics and their spatial variation. This thesis aims to quantify outlet glacier retreat rates across the Atlantic sector of the Arctic and to assess observed changes in relation to climatic, oceanic and glacier-specific controls. Results from a study region in north-west Greenland recorded dramatic retreat on Alison Glacier, coincident with marked atmospheric warming and sea ice decline. However, retreat rates varied substantially within the region, suggesting that fjord width variability and basal topography were important controls on glacier response to external forcing. The influence of fjord width variability was further explored on Novaya Zemlya, Russian High Arctic, where a statistically significant relationship between total retreat and along-fjord width variation was found and the first empirical categories of this relationship were defined. Here, retreat rates were an order of magnitude greater on marine-terminating outlets than on land-terminating glaciers and accelerated retreat from 2000 onwards was linked to sea ice decline. In a further case study, Humboldt Glacier, northern Greenland, retreated rapidly from 1999, coincident with atmospheric warming. However, retreat rates were an order of magnitude greater on its northern section, due to a major subglacial trough, which strongly modulated its response to external forcing. Overall, during the past decade, outlet glacier retreat was widespread and rapid in the Atlantic Arctic. Although some regional-scale patterns of retreat and response to forcing were evident, retreat rates varied markedly. Fjord width variation was identified as an important and widespread control on outlet glacier retreat, which highlights the need to consider glacier-specific factors when forecasting glacier response to climate change

Fanciful Examples

This article defends the use of fanciful examples within the method of wide reflective equilibrium. First, it characterizes the general persuasive role of described cases within that method. Second, it suggests three criteria any example must meet in order to succeed in this persuasive role; fancifulness has little or nothing to do with whether an example is able to meet these criteria. Third, it discusses several general objections to fanciful examples and concludes that they are objections to the abuse of described cases; they identify no special problem with fanciful examples

The Effect of Gamification on Elementary Students’ Spanish Language Achievement and Academic Self-Efficacy

A quasi-experimental, pretest-posttest, non-equivalent control group design was used to examine the effect of gamification on third and fourth grade students’ Spanish language achievement and student academic self-efficacy. In this study, the primary means of incorporating gamification into the experimental group’s Spanish language instruction was through the use of Duolingo®, a computer and mobile app that uses gamification and adaptive learning technology to teach foreign languages. Students in the control group received their regularly scheduled English L1/Spanish L2 class learning activities. The study was 12 weeks in duration. Students were assessed with a 50 question, multiple-choice English to Spanish and Spanish to English pretest covering vocabulary and grammar to control for prior Spanish language achievement. Students were assessed with the Pattern of Adaptive Learning Scales’ (PALS) Academic Efficacy subscale to control for prior academic self-efficacy. The same two instruments were used as posttests with questions arranged in a different order. Analysis showed no significant difference in students’ Spanish achievement between students who used Duolingo® and students who were taught with traditional means. Similarly, analysis showed no significant difference in students’ academic self-efficacy who were taught with Duolingo® versus those who were taught with traditional face-to-face instruction. This demonstrates that Duolingo® is a useful tool for teaching Spanish to elementary students

Quantifying Impacts of Timber Harvesting Operations on Suspended Sediment Inputs to Oregon Coast Range Headwater Streams

Timber harvesting practices can increase fine sediment inputs to streams due to increased hillslope soil erosion and mass wasting of roads, hillslopes, and stream channels. Excessive fine sediment depositions have been shown to impact aquatic ecosystems, fish habitat, and downstream community water supply. Despite these deleterious impacts, the influence of timber harvesting, using contemporary best management practices (BMPs), on sediment inputs to streams remains poorly understood. In this study, I quantified proportional sediment source contributions in forested and harvested Oregon Coast Range watersheds to determine if timber harvesting altered local erosional processes. Additionally, I tested the efficacy of riparian buffers at mitigating sediment movement off recently harvested areas into streams. To do this, I quantified the amounts of sediment moving off harvested hillslopes, through riparian buffers, and along forested, reference hillslopes. Specifically, in Chapter 2, I present research results from a study using sediment fingerprinting analyses to investigate the primary sources of suspended sediment in streams adjacent to recent forest harvesting activity. To do this, I instrumented two catchments, Enos Creek (harvested summer 2016) and Scheele Creek (reference), in fall 2016. Phillips samplers (5–6 per catchment) were deployed longitudinally down each of the streams to enable robust characterization of suspended sediment. I collected samples monthly over two wet seasons and compared the chemical properties of stream sediment samples with those of potential source areas including roads, streambanks, and hillslopes. I analyzed all samples for total carbon, total nitrogen, stable isotopes (δ¹⁵N, δ¹³C), and geochemistry (Fe, K, and Ca). Then, I used a mixing model and Monte-Carlo simulation to quantify the contributions of each potential source area to the suspended sediment. My results indicated that the suspended sediment in the stream draining the harvested watershed was, on average, comprised of 90.2 ± 3.4 % streambank sediment, 7.1 ± 3.1 % hillslope sediment, and 3.6 ± 3.6 % road sediment. Similarly, the proportional contributions of suspended sediment in the stream draining the reference watershed were 93.1 ± 1.8 % streambank sediment, 6.9 ± 1.8 % hillslope sediment, and 0.0 ± 0.0 % road sediment. These results, in conjunction with field observations of few erosional features and low suspended sediment concentrations (SSCs) during high flow events at the harvested watershed outlet, suggest that contemporary timber harvesting BMPs at the site did not substantially alter erosional mechanisms or increase sediment deposition to the stream. Chapter 3 reports the efficacy of the 50-foot fixed-width riparian buffer in the same timber harvested watershed (Enos Creek). To do this, I installed 36 silt fences in early summer 2017 to capture sediment movement from the general harvest area, within the riparian buffer, and from a forested, reference hillslope. Specifically, I installed 12 fences above the riparian buffer at the buffer/harvest edge, 12 fences within the riparian buffer near the stream edge, and 12 fences at the base of an adjacent forested hillslope, also near the stream edge. I collected sediment from each of the silt fences monthly during winter 2017–18 and returned them to the laboratory for drying and weighing. Results provided strong evidence that sediment movement from the general harvest area into the riparian buffer was greater than both sediment movement within the buffer (10.6-times higher; p = 0.0008) and on the forested hillslope (4.6-times higher; p = 0.005). I constructed a linear model to test if ground cover, canopy cover, and localized slope could account for differences in collected sediment mass. This model accounted for 46 % of the variability in the sediment masses in the silt fences. While there was substantial uncertainty in the relative importance of each of my site characteristic variables, my model indicated that ground cover was the most important explanatory variable (48 %), followed by local slope (31 %), and canopy cover (21 %). In sum, these results suggest that the 50-foot fixed-width riparian buffer was sufficient to mitigate sediment movement from the general harvest area to the adjacent stream during the second rainy season after forest harvesting

La aplicación de Estudio del Trabajo, para mejorar la productividad en los servicios de mantenimiento de la Empresa Flashman S.A.C., Lima – 2017

El trabajo de investigación tiene como finalidad el determinar si la aplicación del estudio del trabajo contribuye a la mejora de la productividad, la eficiencia y eficacia en los servicios de mantenimiento que brinda la empresa FLASHMAN S.A.C. La investigación consta de siete capítulos; en el primer capítulo se realizó la identificación del problema de investigación; en el segundo se describe detalles de la metodología, la misma que corresponde a las siguientes características: aplicada – explicativa con el fin de poder establecer la influencia de las variables y demostrar que con la aplicación del estudio del trabajo se puede incrementar la productividad en los servicios de mantenimiento de las unidades de buses que brinda la empresa. FLASHMAN S.A.C. Se tomó como muestra la producción, en términos de servicio de mantenimiento brindado en 60 días de trabajo antes de la aplicación de la mejora propuesta y 60 días después de la aplicación de la mejora propuesta. En tercer capítulo se presentan los procedimientos y resultados obtenidos durante la investigación. En el cuarto capítulo se discute los resultados obtenidos comparándolo con resultados obtenidos por otros estudios similares. En el quinto capítulo se presentan las conclusiones para cada uno de los objetivos que se establecieron y en el sexto capítulo se dan las recomendaciones respectivas. Finalmente, en el último capítulo se detallan las referencias bibliográficas consultadas

Evolutionary Debunking Arguments

Evolutionary debunking arguments (EDAs) are arguments that appeal to the evolutionary origins of evaluative beliefs to undermine their justification. This paper aims to clarify the premises and presuppositions of EDAs—a form of argument that is increasingly put to use in normative ethics. I argue that such arguments face serious obstacles. It is often overlooked, for example, that they presuppose the truth of metaethical objectivism. More importantly, even if objectivism is assumed, the use of EDAs in normative ethics is incompatible with a parallel and more sweeping global evolutionary debunking argument that has been discussed in recent metaethics. After examining several ways of responding to this global debunking argument, I end by arguing that even if we could resist it, this would still not rehabilitate the current targeted use of EDAs in normative ethics given that, if EDAs work at all, they will in any case lead to a truly radical revision of our evaluative outlook