It's hip to be square : The CubeSat revolution

With the launch of the UK’s first commercial CubeSat, UKube-1, on the horizon, Malcolm Macdonald and Christopher Lowe look at what the future holds for this standardised spacecraft platform

What next? Rewilding as a radical future for the British countryside

Rewilding is an optimistic environmental agenda to reverse the loss of biodiversity and reconnect society with nature. This chapter explores Britain’s ecological history, back to the Last Interglacial before the arrival of modern humans, when the climate was similar to today, to analyse how conservationists can learn from the past to rewild the ecosystems of the present and prepare for an uncertain future. Because there is no single point in history that should or could be recreated, rewilding focuses on re-establishing naturally dynamic ecological processes that, through an appropriate sequence of species reintroductions, attempts to move the ecosystem towards a more appropriately biodiverse and functional state. A state that is self-sustaining in the present climate, and that projected for the near future. Specifically, this chapter explores a rewilding solution to conservation challenges associated with over-grazing, limited germination niche availability, and river dynamics: the reintroduction of wolves, wild boar, and beaver respectively. This sequence of reintroductions is suggested to be complimentary, each altering ecosystem dynamics to facilitate the return of the next. Evidence indicates wolves will reduce deer abundance and re-distribute browsing intensity promoting tree regeneration, particularly in riparian areas, increasing woodland availability to the more habitat-dependent wild boar and beaver. An important message behind rewilding is that a rich biodiversity with all guilds well represented, including the ones that polarize public opinion, such as large predators, are important components of ecosystem service rich and self-sustaining ecosystems, particularly in core areas

Through-life modelling of nano-satellite power system dynamics

This paper presents a multi-fidelity approach to finding optimal, mission-specific power system configurations for CubeSats. The methodology begins with propagation of the orbit elements over the mission lifetime, via a continuous-time model, accounting for orbital perturbations (drag, solar radiation and non-spherical geo-potential). Analytical sizing of the power system is then achieved at discrete long-term intervals, to account for the effects of variations in environmental conditions over the mission life. This sizing is based on worst case power demand and provides inputs to a numerical assessment of the in-flight energy collection for each potential solar array deployment configuration. Finally, two objective functions (minimum deviation about the orbit average power and maximum average power over the entire mission) are satisfied to identify the configurations most suitable for the specific mission requirement. Most Nano-satellites are designed with relatively simple, static-models only and tend to be over-engineered as a result, often leading to a power-limited system. The approach described here aims to reduce the uncertainty in energy collection during flight and provide a robust approach to finding the optimal solution for a given set of mission requirements

Parametric CubeSat flight simulation architecture

This paper presents the architecture of a system of models that provides realistic simulation of the dynamic, in-orbit behaviour of a CubeSat. Time-dependent relationships between sub-systems and between the satellite and external nodes (ground stations and celestial bodies) are captured through numerical analysis of a multi-disciplinary set of state variables including position, attitude, stored energy, stored data and system temperature. Model-Based Systems Engineering and parametric modelling techniques are employed throughout to help visualise the models and ensure flexibility and expandability. Operational mode states are also incorporated within the design, allowing the systems engineer to assess flight behaviour over a range of mission scenarios. Finally, both long and short term dynamics are captured using a coupled-model philosophy; described as Lifetime and Operations models. An example mission is analysed and preliminary results are presented as an illustration of early capabilities

SOIL QUALITY INDICATORS AND VEGETATION RESPONSES FOLLOWING ECOLOGICAL RESTORATION THINNING OF PONDEROSA PINE ON THREE SOIL PARENT MATERIAL TYPES UNDER GRAZING AND NON-GRAZING IN NORTHERN ARIZONA

This research was performed in a northern Arizona ponderosa pine (Pinus ponderosa P. & C., Lawson) forest. The objectives were to a) increase understanding of long-term vegetation responses to ecological restoration treatments on three soils types, with and without grazing, b) evaluate the responses soil physical, chemical, and biological properties to restoration treatments, with and without grazing, c) determine the utility of measured soil quality indicators to informing risks to sustainable soils management in southwestern ponderosa pine forests. There were no significant differences in soil bulk density by soil type, treatment type, or grazing treatment. No significant differences in saturated infiltration capacity were observed among treatment types under either grazed or non-grazed conditions. Saturated infiltration capacity was affected by soil type under non-grazed conditions. Grazing resulted in lower soil aggregate stability in comparison to non-grazing. Soil slaking was affected by grazing and forest treatment type. Grazing on basalt-derived soils was less negative to soil slaking potential than limestone-derived soils (p = 0.008). There were no significant differences in soil organic matter, organic carbon, nitrogen, calcium , or potassium (Mg ha-1) in the upper 10 cm of soil based on soil type, forest treatment type, or grazing treatment. There were significant differences in soil magnesium content (Mg ha-1) by soil type. Basalt-derived soils had significantly lower soil phosphorus (P) levels than benmoreite-derived soils. Limestone-derived soils had significantly lower soil S than basalt- and benmoreite-derived soils. Vegetative cover and species richness were affected by forest treatment type, soil parent material type, grazing treatment, and measurement year, depending on life form, longevity, and nativity. As observed by Abella et al. (2015), responses were hierarchically controlled, with soil parent material type often moderating vegetative responses. Limestone-derived soils had the greatest overall total plant cover and benmoreite-derived soils often had the lowest. Grazing affected vegetative cover, depending on measurement year, but rarely affected species richness. This study highlights the importance of considering both inherent and dynamic soil properties when planning ecological restoration treatments since soil parent material type strongly influences vegetative responses of cover and richness, particularly in relation to livestock and wildlife forage production and sustaining healthy native plant communities following forest restoration treatments

Competing narratives : the interplay between racial and ethno-religious identity among Ashkenazi Jewish undergraduate anti-racist peer educators.

This study examined the various ways in which Ashkenazi Jewish undergraduate anti-racism peer educators understood and used their Jewish identity in their work with non-Jewish people of color and white Christians. Ashkenazi Jews, who are Jews of Central European heritage, often find themselves questioning the racial space they occupy. The ways in which students of Ashkenazi Jewish identification compare or contrast their historical and current social position with that of communities of color can either facilitate or disrupt their efforts to be effective anti-racist educators. Fifteen Ashkenazi Jews who are peer facilitators in a nationally-recognized social justice program at a university in the Midwest were interviewed. Three data gathering techniques were utilized: demographic intake form, individual interview, and focus group interview. Participants articulated a complex understanding of the position of Ashkenazi Jews in U.S.-based systems of ethnicity, religion, race and class. Based on these systems, the students claimed that Jews are both insiders and outsiders in American society, targeted and privileged simultaneously in their ethno-religious and class identities. Findings reveal that being Jewish is salient and a distinct identity for this generation of college students; the history of Jewish oppression continues to inform Jewish identity; Jewish students continues to describe a connection with Blacks; and distinctive processes of ethnic and ethno-religious identity development take place for Jewish undergraduates. Findings suggest the need for a new social identity model that addresses the unique racial, ethnic and ethno-religious positionality of Ashkenazi Jewish undergraduates. The author presents a Jewish ethno-religious target development model, along with implications for anti-racism and social justice education and suggestions for further research

Synergistic transcriptional regulation of collagenase gene expression in chondrocytes

PhD ThesisThe proteolytic degradation of articular cartilage in load-bearing joints is a key pathological step in the progression of arthritis, a process mediated by enzymes called collagenases (specifically MMP-1 and MMP-13). My research has focused on the transcriptional regulation of these enzymes in cartilage cells (chondrocytes) in response to a pro-catabolic stimulus which mimics the complex milieu of elevated cytokines found within the arthritic joint. Activating Protein (AP)-1 transcription factors, specifically the c-Fos/c-Jun heterodimer, have previously been shown to be crucial in collagenase gene regulation. c-Fos/c-Jun gene expression, protein production and collagenase promoter enrichment studies identified a temporal deficit between transient c-Fos/c-Jun peak following 1 hour stimulation and the initiation of collagenase gene transcription following 6 hours stimulation. Protein synthesis inhibitor studies indicated that although c-Fos/c-Jun are indeed important, they are not the sole regulators of collagenase gene expression. DNA microarray studies highlighted a number of genes that contributed to transcriptional regulation early within this temporal deficit. Collagenase gene expression was assessed following the siRNA-mediated silencing of these factors. This confirmed that new factors, not previously associated with collagenase gene regulation, were demonstrated to have a significant role in initiating their transcription. This included factors such as activating transcription factor (ATF)3 and early growth response (EGR)2 which demonstrated differential regulation of the collagenase genes, with their silencing affecting MMP13 expression alone. Having identified a number of contributing factors, I then assessed their temporal gene expression and protein production. Comparisons to c-Fos/c-Jun induction confirmed that a number of these factors were transient, similar to AP-1, yet they peaked following longer durations of stimulation. Subsequent siRNA gene silencing of c-Fos and c-Jun led to decreased expression of some of these factors. This demonstrated that these factors may be regulating collagenase expression indirectly by controlling the expression of other transcription factors that, themselves contribute to the regulation of collagenase gene. The present study improves our understanding of how collagenases are regulated in chondrocytes in response to pro-catabolic stimuli. With an improved knowledge of regulation it may be possible to specifically abrogate aberrant collagenases expression in disease. Moreover, by exploiting the differential regulation of collagenases exhibited by some of these factors, there is the potential to mitigate the side effects associated with broad-spectrum collagenase inhibition, thereby removing the barrier to successful treatment.Oliver Bird Rheumatism Programme and the Nuffield foundatio