A Physiological Examination of the Age-related Decline in Photosynthesis in Picea rubens

Numerous conifer species undergo predictable age-related changes in productivity, photosynthesis and foliar morphology and anatomy. While these phenomena have been demonstrated for many species, the physiological mechanisms controlling them are not well understood. In order to better understand this issue, we examined four possible controls of the age-related decline in photosynthesis in red spruce: stomatal limitation, a decline in investment into photosynthetic capacity, nutrient limitations and a demand-side decline in sink: source relations. We investigated these age-related trends in physiology for juvenile, mid-age and old (mean age ~13, ~54 and ~128 years old) red spruce trees in a multi-cohort stand in Maine. In order to examine stomatal limitations, we examined the diurnal trends in gas exchange parameters, whole tree conductivity and stable carbon isotopes. Photosynthetic capacity parameters (Vcmax and Jmax) and the amount of chlorophyll were examined to evaluate investment in photosynthetic capacity. Amounts of biologically important foliar nutrients (N, P and K) were analyzed to rule out any age-related nutrient deficiencies. Finally, the amount of total non-structural carbohydrates (NSC) were examined in order to better understand the supply and demand of photosynthetic end-product for each age class. All gas exchange parameters were measured in situ, on fully-expanded, current year foliage from the top 1/3 of the canopy using a LI-6400 gas exchange system. The transition from juvenile (sub-canopy) to mid-age (emergent) trees is controlled by increased stomatal limitation and decreased photosynthetic capacity. This was demonstrated by decreases in diurnal trends of gas exchange parameters, photosynthetic capacity parameters (Vcmax and Jmax) and chlorophyll between juvenile and older (mid-age and old) trees. Juvenile trees appear to be operating under a “go for broke strategy” to adapt to intraspecific and interspecific competition. The nutrient limitation hypothesis does not hold true, as there are no age-related difference in foliar nutrient quantities. The transition from mid-age to old trees is marked by a change from source (supply) control to sink (demand) control. Analysis of NSC demonstrates a build-up of photosynthate in old trees, indicating that older, established trees may be using a more conservative life-strategy. As a result, we conclude that the decrease in productivity in old P. rubens is not due to decreased photosynthesis, but to a decreased demand for new carbon compounds. Chapter 2 attempts to distinguish between maturational influences and those due to environmental factors, factors external to the meristem by minimizing the confounding factors of tree size and complexity. Growth and gas exchange measurements were performed on reciprocal grafts in the summer of 2004 using field-grown mid-age and old rootstock and potted juvenile rootstock. Results indicate that factors external to the meristem appear to be the principle influence for age-related changes in photosynthesis and physiology in red spruce

Gamification: Game-based Learning / Serious Games and 21st Century Soft Skill Development in Nursing Education

This study examined the development of 21st century skills through gamification, game-based learning (GBL), and serious games in nursing education in institutions of higher education in the United States. This paper reviews the history of gamification in nursing pedagogy through three domains of research. It includes an overview of research related to the development and implementation of gamification, GBL, and serious games in nursing education as well as the impact on the development of 21st century skills in digital natives. The focus was on the historical literature related to gamification, GBL, and serious games at institutions of higher education in nursing education to identify and analysis occurrences of 21st century skill development in historical research. Results were obtained through qualitative content analysis through the MAXQAD qualitative software program. Overall, the findings supported the use of gamification, GBL, and serious games in nursing education contributed to the development of 21st century skills among nursing students at institutions of higher education in the United States

Disability, access and design: a study of wheelchair access.

The aim of this study is to determine wheelchair user's views about access and ascertain whether designers are able to contribute to issues pertaining to inclusion through design solutions. Popular constructions of disability have established a relatively powerless and deviant status for the disabled population when compared to their able bodied peers. Regulatory controls and legislation require that builders and designers are sensitised to the needs of disabled people, but there is no legislative process to endorse disabled peoples request for a fully inclusive and accessible lifestyle. The enquiry is divided into two phases. The first phase considers access issues from a sample of wheelchair users via the use of focus groups and individual interviews. The data attained and information collated for the literature review leads the author to conclude that designers should consult with end users throughout the design process. During the second phase of the study the author proposes a model of inclusive design and an associated design resource. The author advocates that this is to be used by designers and development professionals to ensure inclusion within society is attained for all sectors of the community. The study concludes that, historically, society has responded to the needs of the disabled by providing separate and special services based on each individual's impairment, as opposed to the promotion of an equitable lifestyle for all. Inclusive design focuses on the design of the environment and not individual impairments. It is a process that promotes inclusivity for all sectors of society regardless of age, race, gender, sexuality or disability. Its principles consider diversity, and provides for an inclusive environment that can help break down barriers and exclusion as everyone will benefit from the end result

The impact of strictly protected areas in a deforestation hotspot

Protected areas are often thought of as a key conservation strategy for avoiding deforestation and retaining biodiversity; therefore, it is crucial to know how effective they are at achieving this purpose. Using a case study from Queensland, Australia, we identified and controlled for bias in allocating strictly protected areas (IUCN Class I and II) and evaluated their impact (in terms of avoiding deforestation) using statistical matching methods. Over the 30 years between 1988 and 2018, approximately 70,481 km2 of native forest was cleared in the study region. Using statistical matching, we estimated that 10.5% (1,447 km2) of Category I and II (strict) protected areas would have been cleared in the absence of protection. Put differently, 89.5% of strictly protected areas are unlikely to have been cleared, even if they were never protected. While previous studies have used statistical matching at a country or state level, we conducted an analysis that allows regional comparison across a single State. Our research indicates that strictly protected areas are marginally effective at preventing deforestation, and this likely due to biases in establishing protected areas on unproductive land

Notch/Delta signaling constrains reengineering of pro-T cells by PU.1

PU.1 is essential for early stages of mouse T cell development but antagonizes it if expressed constitutively. Two separable mechanisms are involved: attenuation and diversion. Dysregulated PU.1 expression inhibits pro-T cell survival, proliferation, and passage through β-selection by blocking essential T cell transcription factors, signaling molecules, and Rag gene expression, which expression of a rearranged T cell antigen receptor transgene cannot rescue. However, Bcl2 transgenic cells are protected from this attenuation and may even undergo β-selection, as shown by PU.1 transduction of defined subsets of Bcl2 transgenic fetal thymocytes with differentiation in OP9-DL1 and OP9 control cultures. The outcome of PU.1 expression in these cells depends on Notch/Delta signaling. PU.1 can efficiently divert thymocytes toward a myeloid-like state with multigene regulatory changes, but Notch/Delta signaling vetoes diversion. Gene expression analysis distinguishes sets of critical T lineage regulatory genes with different combinatorial responses to PU.1 and Notch/Delta signals, suggesting particular importance for inhibition of E proteins, Myb, and/or Gfi1 (growth factor independence 1) in diversion. However, Notch signaling only protects against diversion of cells that have undergone T lineage specification after Thy-1 and CD25 up-regulation. The results imply that in T cell precursors, Notch/Delta signaling normally acts to modulate and channel PU.1 transcriptional activities during the stages from T lineage specification until commitment