On the kidney exchange problem: cardinality constrained cycle and chain problems on directed graphs: a survey of integer programming approaches

The Kidney Exchange Problem (KEP) is a combinatorial optimization problem and has attracted the attention from the community of integer programming/combinatorial optimisation in the past few years. Defined on a directed graph, the KEP has two variations: one concerns cycles only, and the other, cycles as well as chains on the same graph. We call the former a Cardinality Constrained Multi-cycle Problem (CCMcP) and the latter a Cardinality Constrained Cycles and Chains Problem (CCCCP). The cardinality for cycles is restricted in both CCMcP and CCCCP. As for chains, some studies in the literature considered cardinality restrictions, whereas others did not. The CCMcP can be viewed as an Asymmetric Travelling Salesman Problem that does allow subtours, however these subtours are constrained by cardinality, and that it is not necessary to visit all vertices. In existing literature of the KEP, the cardinality constraint for cycles is usually considered to be small (to the best of our knowledge, no more than six). In a CCCCP, each vertex on the directed graph can be included in at most one cycle or chain, but not both. The CCMcP and the CCCCP are interesting and challenging combinatorial optimization problems in their own rights, particularly due to their similarities to some travelling salesman- and vehicle routing-family of problems. In this paper, our main focus is to review the existing mathematical programming models and solution methods in the literature, analyse the performance of these models, and identify future research directions. Further, we propose a polynomial-sized and an exponential-sized mixed-integer linear programming model, discuss a number of stronger constraints for cardinality-infeasible-cycle elimination for the latter, and present some preliminary numerical results.

Implementation of China's new policies on organ procurement: An important but challenging step forward

In the last decade, health authorities in China have made a series of policy announcements concerning organ procurement programs and changes in practice have been intermittently reported (1). The international community of transplant professionals has followed these reports closely, preoccupied with one fundamental issue: the procurement of organs from executed prisoners, a practice that for many years has provided the majority of organs transplanted in China. Sharif et al. describe this practice as “ethically indefensible” (2), an evaluation that reflects the position embraced by the international community for more than two decades (3-5). Sharif et al. express concern that whilst some transplant programs in China have ceased using organs from executed prisoners, others continue to do so, and that all organs procured from the deceased may be allocated through a collective pool as part of the new China Organ Transplant Response System, effectively “laundering” organs obtained from prisoners. They also note that one of the new strategies to encourage deceased donation of organs among the Chinese public has involved financial incentives for donor families, another practice that has been strongly critiqued by the international professional community and global health authorities (6,7).

In China and in the United States, proponents of organ procurement from executed prisoners have argued that prisoners should not be denied the option to donate organs after their death if they so choose, as this may provide them or their families solace and an opportunity for moral, spiritual or social redemption (8,9). However, the predominant argument in favour of the practice appears to be essentially pragmatic: prisoners condemned to death represent an additional pool of potential “donors” with organs that will otherwise “go to waste” (10). In contrast, international professional societies and the World Health Organization among others have argued that the practice not only violates the core principles of medical ethics but also thereby undermines efforts to establish a sufficient supply of deceased donor organs. In this commentary, we reaffirm the ethics policy of The Transplantation Society (TTS) concerning organ procurement from executed prisoners (4), and briefly discuss the implications of this policy for international professional engagement with China at this time of significant evolution of Chinese organ procurement programs.

A bit of a dirty word: 'feminism' and female teachers identifying as feminist

Following the identification of a gap in the literature around reasons for contemporary women’s self-identification as ‘feminist’ (Swirsky & Angelone, 2015), this paper discusses an empirical study of an intergenerational group of contemporary Australian female teachers collaboratively designing English curriculum around girls’ media. The paper explores the group’s shared conversations around feminism, over a series of meetings, as we (teachers and researcher) plan curriculum and negotiate broader subject positions possible for girls and women. These contexts include the competing discourses of feminism and postfeminism and how these mediate texts chosen for study, our pedagogical approaches, and the ways we experience our own lives. In this study, we struggle to find a shared language, across generations, with which to work collaboratively in a community of practice committed to the critical study of media, but involving different individual orientations to ‘feminism’. This is a space in which impediments to the feminist study of girls’ media quickly emerge. The paper also serves as a reminder that feminist scholarship takes place in schools, as well as in the academy, and that the gender studies work teachers do in schools is potentially whole population work, worthy of keen attention in the gender studies academic mainstream.

A collaborative development of quality mathematics assessment tasks to promote preservice teachers’ professional eye

The Mathematics Teacher Education Collective (MTEC) — a self-study group based at the University of British Columbia, Canada — collaborates to enhance our pedagogical practice in mathematics teacher education through analysing, constructing, and reflecting on variations to assessment tasks. The theoretical framework underlying the establishment of the MTEC is based on Lave and Wenger’s (1991) view of learning through a Community of Practice (CoP). “Communities of practice are groups of people who share a concern or a passion for something they do and learn how to do it better as they interact regularly” (Wenger-Trayner, 2011, http://wenger-trayner.com/theory/). Three characteristics are viewed as crucial to the CoP: domain, community, and practice. The shared domain for MTEC is a commitment to gaining a deeper understanding of practice as mathematics teacher educators. In particular, as members we are interested in better understanding the role and development of tasks for learning to teach mathematics. As a community MTEC engages “in joint activities and discussions, [that] help each other, and share information” (Wenger-Trayner, 2011, http://wenger-trayner.com/theory/), with the goal to build relationships that provide members with opportunities to learn from one other. MTEC members are practitioners in the field. The success of the MTEC is based on the sharing, evaluation and critical reflection of assessment tasks and pedagogical approaches refined by the CoP.

Upholding whose right? Discretionary police powers to punish, collective 'pre-victimisation and the dilution of individual rights

This article uses the example of Victoria’s alcohol-related banning notice provisions to explore the changing conception of balance within criminal justice processes. Despite the formalisation of individual rights within measures such as Victoria’s Charter of Human Rights and Responsibilities Act 2006, the discretionary power of the police to issue on-the-spot punishments in response to actual or potential criminal behaviour has increased steadily. A key driver, evident across the parliamentary debates of the banning legislation, is a presumed need to protect the broader community of potential victims. As a result, the individual rights of those accused (but not necessarily convicted) of undesirable behaviours are increasingly subordinated to the pre-emptive protection of the law-abiding majority. This shift embodies a largely unsubstantiated notion of collective pre-victimisation. Significantly, despite the expectations of Victoria’s Charter, measures such as banning notices have been enacted with insufficient evidence of the underlying collective risk, of their likely effectiveness and without meaningful ongoing scrutiny. The motto of Victoria Police – Uphold the Right –appears to belie a growing uncertainty over whose rights should be upheld and how.

The Planned and the Emergent: An Alternative Model of Learning and Literacy

Within academic institutions, writing centers are uniquely situated, socially rich sites for exploring learning and literacy. I examine the work of the Michigan Tech Writing Center's UN 1002 World Cultures study teams primarily because student participants and Writing Center coaches are actively engaged in structuring their own learning and meaning-making processes. My research reveals that learning is closely linked to identity formation and leading the teams is an important component of the coaches' educational experiences. I argue that supporting this type of learning requires an expanded understanding of literacy and significant changes to how learning environments are conceptualized and developed. This ethnographic study draws on data collected from recordings and observations of one semester of team sessions, my own experiences as a team coach and UN 1002 teaching assistant, and interviews with Center coaches prior to their graduation. I argue that traditional forms of assessment and analysis emerging from individualized instruction models of learning cannot fully account for the dense configurations of social interactions identified in the Center's program. Instead, I view the Center as an open system and employ social theories of learning and literacy to uncover how the negotiation of meaning in one context influences and is influenced by structures and interactions within as well as beyond its boundaries. I focus on the program design, its enaction in practice, and how engagement in this type of writing center work influences coaches' learning trajectories. I conclude that, viewed as participation in a community of practice, the learning theory informing the program design supports identity formation —a key aspect of learning as argued by Etienne Wenger (1998). The findings of this study challenge misconceptions of peer learning both in writing centers and higher education that relegate peer tutoring to the role of support for individualized models of learning. Instead, this dissertation calls for consideration of new designs that incorporate peer learning as an integral component. Designing learning contexts that cultivate and support the formation of new identities is complex, involves a flexible and opportunistic design structure, and requires the availability of multiple forms of participation and connections across contexts.

Analysis of Land Use Change as a Method of Predicting Water Demands in an Urbanizing Environment: Redland, Miami-Dade County, Florida

The fluctuation in water demand in the Redland community of Miami-Dade County was examined using land use data from 2001 and 2011 and water estimation techniques provided by local and state agencies. The data was converted to 30 m mosaicked raster grids that indicated land use change, and associated water demand measured in gallons per day per acre. The results indicate that, first, despite an increase in population, water demand decreased overall in Redland from 2001 to 2011. Second, conversion of agricultural lands to residential lands actually caused a decrease in water demand in most cases while acquisition of farmland by public agencies also caused a sharp decline. Third, conversion of row crops and groves to nurseries was substantial and resulted in a significant increase in water demand in all such areas converted. Finally, estimating water demand based on land use, rather than population, is a more accurate approach.

Descriptive analysis of the test of everyday attention for children in a Spanish normative sample

Introduction. Test of Everyday Attention for Children (TEA-Ch) has been validated in different countries demonstrating that it is an instrument with a correct balance between reliability and duration. Given the shortage of trustworthy instruments of evaluation in our language for infantile population we decide to explore the Spanish version of the TEA-Ch. Methods. We administered TEA-Ch (version A) to a sample control of 133 Spanish children from 6 to 11 years enrolled in school in the Community of Madrid. Four children were selected at random by course of Primary Education, distributing the sex of equivalent form. Descriptive analysis and comparison by ages and sex in each of the TEA-Ch's subtests were conducted to establish a profile of the sample. In order to analyze the effect of the age, subjects were grouped in six sub-samples: 6, 7, 8, 9, 10 and 11 years-old. Results. This first descriptive analysis demonstrates age exerted a significant effect on each measure, due to an important "jump" in children's performance between 6 and 7 years-old. The effect of sex was significant only in two visual attention measures (Sky Search & Map) and interaction age and sex exerted a significant effect only in the dual task (Score DT). Conclusions. The results suggest that the Spanish version of the TEA-Ch (A) might be a useful instrument to evaluate attentional processes in Spanish child population.

Negotiating national identity on film: competing readings of Zhang Yimou’s 'Hero'

How are national identities transformed? If they are mostly narratives of belonging to a community of history and destiny to which people subscribe, those boundary-making procedures that constitute the political field by instituting differences can provide a tentative answer to this question. This paper is concerned with one such cultural practice, namely film-viewing. Globalisation, a boundary-blurring practice, has been the backdrop against which transformations in national identity are often discussed, either bemoaned as cultural imperialism or celebrated as ongoing hybridisation. This piece of research took Zhang Yimou’s controversial film Hero as a point of departure, and asked groups of Chinese audiences how they understood the Chinese identity it conveys. Although it is still a work in progress, provisional results are reported below.

A Grammar of Ts'ixa (Kalahari Khoe)

Ts’ixa is an endangered language of northern Botswana. It belongs to the Kalahari branch of the Khoe-Kwadi language family and is nowadays spoken by a small community of 200 individuals residing in the village of Mababe, Ngamiland. The internal affiliation of Ts’ixa within Kalahari Khoe is not clear, as the language displays affinities to both the western Kalahari Khoe language Khwe and the eastern Kalahari Khoe language Shua. The present work is the first attempt at providing a systematic description of Ts’ixa, based on phonological, morphological and syntactical features. Data from related Khoe languages, as well as from unrelated “Khoisan” languages of the Kx’a and Tuu families is used to locate Ts’ixa in both a genealogical and an areal framework. Findings suggest that Ts’ixa was shaped by a history of migration and contact between both related and unrelated languages, leading to a unique profile different from both Khwe and Shua, but with strong typological affinities to the Kalahari Basin as a linguistic area.

The potential of symbolic approximation. Disentangling the effects of approximation vs. calculation demands in nonsymbolic and symbolic representations.

Mathematical skills that we acquire during formal education mostly entail exact numerical processing. Besides this specifically human faculty, an additional system exists to represent and manipulate quantities in an approximate manner. We share this innate approximate number system (ANS) with other nonhuman animals and are able to use it to process large numerosities long before we can master the formal algorithms taught in school. Dehaene´s (1992) Triple Code Model (TCM) states that also after the onset of formal education, approximate processing is carried out in this analogue magnitude code no matter if the original problem was presented nonsymbolically or symbolically. Despite the wide acceptance of the model, most research only uses nonsymbolic tasks to assess ANS acuity. Due to this silent assumption that genuine approximation can only be tested with nonsymbolic presentations, up to now important implications in research domains of high practical relevance remain unclear, and existing potential is not fully exploited. For instance, it has been found that nonsymbolic approximation can predict math achievement one year later (Gilmore, McCarthy, & Spelke, 2010), that it is robust against the detrimental influence of learners´ socioeconomic status (SES), and that it is suited to foster performance in exact arithmetic in the short-term (Hyde, Khanum, & Spelke, 2014). We provided evidence that symbolic approximation might be equally and in some cases even better suited to generate predictions and foster more formal math skills independently of SES. In two longitudinal studies, we realized exact and approximate arithmetic tasks in both a nonsymbolic and a symbolic format. With first graders, we demonstrated that performance in symbolic approximation at the beginning of term was the only measure consistently not varying according to children´s SES, and among both approximate tasks it was the better predictor for math achievement at the end of first grade. In part, the strong connection seems to come about from mediation through ordinal skills. In two further experiments, we tested the suitability of both approximation formats to induce an arithmetic principle in elementary school children. We found that symbolic approximation was equally effective in making children exploit the additive law of commutativity in a subsequent formal task as a direct instruction. Nonsymbolic approximation on the other hand had no beneficial effect. The positive influence of the symbolic approximate induction was strongest in children just starting school and decreased with age. However, even third graders still profited from the induction. The results show that also symbolic problems can be processed as genuine approximation, but that beyond that they have their own specific value with regard to didactic-educational concerns. Our findings furthermore demonstrate that the two often con-founded factors ꞌformatꞌ and ꞌdemanded accuracyꞌ cannot be disentangled easily in first graders numerical understanding, but that children´s SES also influences existing interrelations between the different abilities tested here.

Ana's tragedy - and Europe's a contemplation over Romani, belonging and citizenship making in a Europe of migration

This article deals with the notion of belonging in today’s multi-ethnic Sweden and hints at perpectives of future European identity-building. On the basis of Frantz Fanon’s understanding of colonialism and the colonized mentality as theoretical, the article deals with the situation of Roma in Sweden – and Europe. With the story of a young Roma woman that has migrated to Sweden from Hungary as point of departure, the article addresses the situation for Romani people, but also for other migrants in Europe, with particular focus on who are allowed to belong to the community of Swedish and European citizens, and who are not

A gallery walk: 'drawing out' understandings of collaborative self-study in teacher education

The Collaborative Reflective Experience and Practice in Education (CREPE) Research Group formed mid 2014 as a group of eight teacher educators interested in working collaboratively to improve our teaching practice through self-study methodology. Located at distance across the three campuses of Deakin University in Victoria, Australia and from the disciplines of mathematics, science, visual arts, performing arts, and curriculum and pedagogy, we aimed to better understand, improve, and share our practices as teacher-educators. While a few of us had engaged in self-study previously, all were comfortable with observing some kind of professional reflective/reflexive practice. We shared the intention of engaging in the scholarship (teaching practice and research) of self-study methodology via community of practice approaches, focusing on our collaborative (overarching) research as well as engaging in focused research simultaneously. It is our efforts towards collaborative research that are the subject of this chapter.

Every day you learn something : learning for life? Neighbourhood houses, adult learning and transitions to higher education

This book comes from a research project titled ‘Lifelong Learning? Neighbourhood Houses, Adult Learning and Transitions to Higher Education’ (T Ollis, Starr, Ryan, Angwin, & Harrison, 2016). This research has examined adult learning in the context of Neighbourhood Houses in the regions of Geelong and South Western Victoria.The research was conducted in 2015 and 2016 and sought to examine the learning experiences of adult learners who participate in the education programs of Neighbourhood Houses. The focus was on second chance learners and their transition pathways to higher education such as TAFE and University. A second group of learners were identified during the research process – later life learners. These learners were engaging with Neighbourhood Houses for personal interest learning and social and community connection. This small book provides a snapshot of the stories of learners who were involved in this research. It tells the lived stories of the participants, which is important as learning and education are connected with the ongoing development of ourselves as human beings. Learning is essential to our personhood and impacts on adults in terms of their welfare, health and prosperity over a lifetime. Many of the learners’ stories outlined in this book reveal checkered histories of education. Some have experienced learning difficulties, others have experienced family trauma that prevented them from finishing secondary schooling. Some of the stories describe issues related to reskilling or retraining in later life, responding to industry changes and work in the Greater Geelong and South West regions. Others were pursuing recreation and social connection and came to the Neighbourhood Houses to learn crafts, writing, photography and computer literacy skills. In almost all accounts of learning in this book, individuals had experienced less social isolation by being connected to others in the unique social environment of Neighbourhood houses.

The flora and vegetation of rocky outcrops in three municipalities in the northern region of Ceará, Brazil: phytosociological characterization

This study aims to identify the flora and vegetation of rocky outcrops of low altitude and confined in the municipalities of Sobral, Groaíras and Santa Quitéria (Ceará state, Brazil), to propose a phytosociological classification for the xerophilous communities. We selected five stations in areas with high proportion of bare rock (> 80%), and the field work were conducted in March 2014 and 2015 respectively (3º 56’ S and 40º 23’ W, 4º 01’ S and 40º 05’ W, 4º 07’’ S and 40º 08’ W, 4º 09’ S and 40º 09’ W and 4º 03’ S and 40º 00’ W). Floristic relevés were made following the Braun-Blanquet classic sigmatist method. The minimum areas of the floristic relevés vary between 8 e 16 m². All the plant species growing in cracks, crevices and vegetation "spots" that can be found in these habitats were identified. The classification of the relevés was made through the Twinspan. The floristic list is composed of 89 species, distributed in 61 genera and 29 families. Fabaceae was the most representative in species richness, 20 species, followed by Poaceae (10 spp.), Euphorbiaceae (7 spp.) and Convolvulaceae (6 spp.). 22 Brazilian endemisms have been identified. Based in the phytosociological analysis and in the classification results we identified five groups and two communities can be clearly distinguished: community of Pilosocereus gounellei FA.C.Weber) Byles & Rowley and Encholirium spectabile Mart. ex Schult. & Schult.f. and the community of Crateva tapia L. and Combretum leprosum Mart..