Balancing the (carbon) budget: Using linear inverse models to estimate carbon flows and mass-balance 13C:15N labelling experiments in low oxygen sediments.

Over 1 million km² of seafloor experience permanent low-oxygen conditions within oxygen minimum zones (OMZs). OMZs are predicted to grow as a consequence of climate change, potentially affecting oceanic biogeochemical cycles. The Arabian Sea OMZ impinges upon the western Indian continental margin at bathyal depths (150 - 1500 m) producing a strong depth dependent oxygen gradient at the sea floor. The influence of the OMZ upon the short term processing of organic matter by sediment ecosystems was investigated using in situ stable isotope pulse chase experiments. These deployed doses of ¹³C:¹⁵N labeled organic matter onto the sediment surface at four stations from across the OMZ (water depth 540 - 1100 m; [O₂] = 0.35 - 15 μM). In order to prevent experimentally anoxia, the mesocosms were not sealed. ¹³C and ¹⁵N labels were traced into sediment, bacteria, fauna and ¹³C into sediment porewater DIC and DOC. However, the DIC and DOC flux to the water column could not be measured, limiting our capacity to obtain mass-balance for C in each experimental mesocosm. Linear Inverse Modeling (LIM) provides a method to obtain a mass-balanced model of carbon flow that integrates stable-isotope tracer data with community biomass and biogeochemical flux data from a range of sources. Here we present an adaptation of the LIM methodology used to investigate how ecosystem structure influenced carbon flow across the Indian margin OMZ. We demonstrate how oxygen conditions affect food-web complexity, affecting the linkages between the bacteria, foraminifera and metazoan fauna, and their contributions to benthic respiration. The food-web models demonstrate how changes in ecosystem complexity are associated with oxygen availability across the OMZ and allow us to obtain a complete carbon budget for the stationa where stable-isotope labelling experiments were conducted.

Use of bacterial whole-genome sequencing to investigate local persistence and spread in bovine tuberculosis

Mycobacterium bovis is the causal agent of bovine tuberculosis, one of the most important diseases currently facing the UK cattle industry. Here, we use high-density whole genome sequencing (WGS) in a defined sub-population of M. bovis in 145 cattle across 66 herd breakdowns to gain insights into local spread and persistence. We show that despite low divergence among isolates, WGS can in principle expose contributions of under-sampled host populations to M. bovis transmission. However, we demonstrate that in our data such a signal is due to molecular type switching, which had been previously undocumented for M. bovis. Isolates from farms with a known history of direct cattle movement between them did not show a statistical signal of higher genetic similarity. Despite an overall signal of genetic isolation by distance, genetic distances also showed no apparent relationship with spatial distance among affected farms over distances <5 km. Using simulations, we find that even over the brief evolutionary timescale covered by our data, Bayesian phylogeographic approaches are feasible. Applying such approaches showed that M. bovis dispersal in this system is heterogeneous but slow overall, averaging 2 km/year. These results confirm that widespread application of WGS to M. bovis will bring novel and important insights into the dynamics of M. bovis spread and persistence, but that the current questions most pertinent to control will be best addressed using approaches that more directly integrate WGS with additional epidemiological data.

Blood: Tests used to assess the physiological and immunological properties of blood.

The properties of blood and the relative ease of access to which it can be retrieved make it an ideal source to gauge different aspects of homeostasis within an individual, form an accurate diagnosis, and formulate an appropriate treatment regime. Tests used to determine blood parameters such as the erythrocyte sedimentation rate, hemoglobin concentration, hematocrit, bleeding and clotting times, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean cell volume, and determination of blood groups are routinely used clinically, and deviations outside the normal range can indicate a range of conditions such as anemia, pregnancy, dehydration, overhydration, infectious disease, cancer, thyroid disease, and autoimmune conditions, to mention a few. As these tests can be performed relatively inexpensively and do not require high levels of technical expertise, they are ideally suited for use in the teaching laboratory, enabling undergraduate students to link theory to practice. The practicals described here permit students to examine their own blood and that of their peers and compare these with clinically accepted normal ranges. At the end of the practicals, students are required to answer a number of questions about their findings and to link abnormal values to possible pathological conditions by answering a series of questions based on their findings.

A Brief Review to Integrated Energy System and Energy Internet 综合能源系统与能源互联网简述

Integrated energy system and Energy Internet are two hot topics in the field of energy. In this paper, these two concepts and their focuses are summarized and analyzed. Typical research in the areas of integrated energy system and Energy Internet is reviewed. The research concerns and technologies of these two concepts are then outlined respectively. The differences and similarities of these two concepts and their future development are discussed.

'"To have its cake and eat it too:" US policy toward South Africa during the Kennedy administration

The assumption that US policy toward Africa was characterized by continuity during the cold war has recently been challenged by scholars who argue that President John F. Kennedy embarked on an African policy that was distinct from his predecessors. This may be true for black Africa, but Kennedy’s support for African nationalism did not extend to South Africa. This article reveals that Kennedy’s cold war priorities ensured continuity in US policy toward the apartheid state and, in some cases, additional cooperation as cold war crises increased the perceived importance of South Africa as an ideological and strategic ally and bastion against communism on a rapidly changing continent. This article also explores the role South Africa’s apartheid government played in this cold war alliance. The ruling National Party recognized its importance to US foreign policy goals and used this to stave off serious American criticism of its racial policies, deflect attention in the United Nations, and ensure continued economic and military cooperation with the United States.

How to promote professional competence and identity in social work students

Background: Field placement experiences are frequently cited in the literature as having most impact on a student social worker’s learning as they emerge into the profession. Placements are integral to the development of practice competence and in acquiring a sense of social work identity. However research on the effectiveness of educational strategies used to deliver learning and assess competence during placement are scarce. Internationally, pressures to meet increasing numbers of student enrolments have raised concerns about the potential impact on the quality of placements and practice teaching provided. These pressures may also impact on the appropriate transfer and application of learning to the student’s practice.
Aim: To identify learning activities rated most useful for developing professional practice competence and professional identity of social work students.
Method: Data were collected from 396 students who successfully completed their first or final placement during 2013-2014 and were registered at one of two Universities in Northern Ireland. Students completed a self-administered questionnaire which covered: placement setting and service user group; type of supervision model; frequency of undertaking specific learning activities; who provided the learning; which activities contributed to their developing professional competence and identity and their overall satisfaction.
Our findings confirmed the centrality of the supervisory relationship as the vehicle to enable quality student learning. Shadowing others, receiving regular supervision and receiving constructive feedback were the tasks that students reported as ‘most useful’ to developing professional identity, competence and readiness to practice. Disturbingly over 50% of students reported that linking practice to the professional codes, practice foci and key roles were not valued as ‘useful’ in terms of readiness to practice, feeling competent and developing professional social work identity. These results offer strong insights into how both the University and the practice placement environment needs to better prepare, assess and support students during practice placements in the field.