ALCH: An Imperative Language for Chemical Reaction Network-Controlled Tile Assembly

In 2015 Schiefer and Winfree introduced the chemical reaction network-controlled tile assembly model (CRN-TAM), a variant of the abstract tile assembly model (aTAM), where tile reactions are mediated via non-local chemical signals. In this paper, we introduce ALCH, an imperative programming language for specifying CRN-TAM programs. ALCH contains common features like Boolean variables, conditionals, and loops. It also supports CRN-TAM-specific features such as adding and removing tiles. A unique feature of the language is the branch statement, a nondeterministic control structure that allows us to query the current state of tile assemblies. We also developed a compiler that translates ALCH to the CRN-TAM, and a simulator that simulates and visualizes the self-assembly of a CRN-TAM program. Using this language, we show that the discrete Sierpinski triangle can be strictly self-assembled in the CRN-TAM. This solves an open problem that the CRN-TAM is capable of self-assembling infinite shapes at scale one that the aTAM cannot. ALCH allows us to present this construction at a high level, abstracting species and reactions into C-like code that is simpler to understand. Our construction utilizes two new CRN-TAM techniques that allow us to tackle this open problem. First, it employs the branching feature of ALCH to probe the previously placed tiles of the assembly and detect the presence and absence of tiles. Second, it uses scaffolding tiles to precisely control tile placement by occluding any undesired binding sites

Neutral red retention time assay in determination of toxicity of nanoparticles

The neutral red retention time (NRRT) assay is useful for detecting decreased lysosomal membrane stability in haemocytes sampled from bivalves, a phenomenon often associated with exposure to environmental pollutants including nanomaterials. Bivalves are popular sentinel species in ecotoxicology and use of NRRT in study of species in the genus Mytilus is widespread in environmental monitoring. The NRRT assay has been used as an in vivo test for toxicity of carbon nanoparticles (Moore MN, Readman JAJ, Readman JW, Lowe DM, Frickers PE, Beesley A. 2009. Lysosomal cytotoxicity of carbon nanoparticles in cells of the molluscan immune system: An in vivo study. Nanotoxicology. 3 (1), 40-45). We here report application of this assay adapted to a microtitre plate format to a panel of metal and metal oxide nanoparticles (2 ppm). This showed that copper, chromium and cobalt nanoparticles are toxic by this criterion while gold and titanium nanoparticles are not. As the former three nanoparticles are often reported to be cytotoxic while the latter two are thought to be non-cytotoxic, these data support use of NRRT as a general in vitro assay in nanotoxicology

Policy options for the world’s primary forests in multilateral environmental agreements

We identify policies that would provide a solid foundation in key international negotiations to ensure that primary forests persist into the 21st Century. A novel compilation of primary forest cover and other data revealed that protection of primary forests is a matter of global concern being equally distributed between developed and developing countries. Almost all (98%) of primary forest is found within 25 countries with around half in five developed ones (USA, Canada, Russia, Australia, and NZ). Only approximate to 22% of primary forest is found in IUCN Protected Areas Categories I-VI, which is approximately 5% of preagriculture natural forest cover. Rates of deforestation and forest degradation are rapid and extensive, and the long-term integrity of primary forest cannot be assumed. We recommend four new actions that could be included in climate change, biodiversity, and sustainable development negotiations: (1) recognize primary forests as a matter of global concern within international negotiations; (2) incorporate primary forests into environmental accounting; (3) prioritize the principle of avoided loss; and (4) universally accept the important role of indigenous and community conserved areas. In the absence of specific policies for primary forest protection, their unique biodiversity values and ecosystem services will continue to erode

How to … grow a team in clinical education research

The Incubator for Clinical Education Research (ClinEdR) is a UK-wide network, established with support from the National Institute for Health and Care Research (NIHR), to lead initiatives to build capacity in the field. Our lived experiences as members of the NIHR ClinEdR Incubator and wider literature are woven into this ‘How to …’ paper, which outlines what to consider as you seek to grow and develop a ClinEdR team. This paper sets out pragmatic steps to grow an effective ClinEdR team that has a wider impact and mutual benefits for its members and their institution(s). Growing a ClinEdR team requires more than a dynamic character to bring people together. In our view, you can grow a ClinEdR team with other people through a structured, well-thought-out approach, in which its members develop through collaborative work to achieve a shared objective

Language of Lullabies: The Russification and De-Russification of the Baltic States

This article argues that the laws for promotion of the national languages are a legitimate means for the Baltic states to establish their cultural independence from Russia and the former Soviet Union

Impact on and use of health services by international migrants: questionnaire survey of inner city London A&E attenders

BACKGROUND: Changing immigration trends pose new challenges for the UK's open access health service and there is considerable speculation that migrants from resource-poor countries place a disproportionate burden on services. Data are needed to inform provision of services to migrant groups and to ensure their access to appropriate health care. We compared sociodemographic characteristics and impact of migrant groups and UK-born patients presenting to a hospital A&E/Walk-In Centre and prior use of community-based General Practitioner (GP) services. METHODS: We administered an anonymous questionnaire survey of all presenting patients at an A&E/Walk-In Centre at an inner-city London hospital during a 1 month period. Questions related to nationality, immigration status, time in the UK, registration and use of GP services. We compared differences between groups using two-way tables by Chi-Square and Fisher's exact test. We used logistic regression modelling to quantify associations of explanatory variables and outcomes. RESULTS: 1611 of 3262 patients completed the survey (response rate 49.4%). 720 (44.7%) were overseas born, representing 87 nationalities, of whom 532 (73.9%) were new migrants to the UK (≤10 years). Overseas born were over-represented in comparison to local estimates (44.7% vs 33.6%; p < 0.001; proportional difference 0.111 [95% CI 0.087–0.136]). Dominant immigration status' were: work permit (24.4%), EU citizens (21.5%), with only 21 (1.3%) political asylum seekers/refugees. 178 (11%) reported nationalities from refugee-generating countries (RGCs), eg, Somalia, who were less likely to speak English. Compared with RGCs, and after adjusting for age and sex, the Australians, New Zealanders, and South Africans (ANS group; OR 0.28 [95% CI 0.11 to 0.71]; p = 0.008) and the Other Migrant (OM) group comprising mainly Europeans (0.13 [0.06 to 0.30]; p = 0.000) were less likely to have GP registration and to have made prior contact with GPs, yet this did not affect mode of access to hospital services across groups nor delay access to care. CONCLUSION: Recently arrived migrants are a diverse and substantial group, of whom migrants from refugee-generating countries and asylum seekers comprise only a minority group. Service reorganisation to ensure improved access to community-based GPs and delivery of more appropriate care may lessen their impact on acute services

Considering weed management as a social dilemma bridges individual and collective interests

Weeds pose severe threats to agricultural and natural landscapes worldwide. One major reason for the failure to effectively manage weeds at landscape scales is that current Best Management Practice guidelines, and research on how to improve such guidelines, focus too narrowly on property-level management decisions. Insufficiently considered are the aggregate effects of individual actions to determine landscape-scale outcomes, or whether there are collective practices that would improve weed management outcomes. Here, we frame landscape-scale weed management as a social dilemma, where trade-offs occur between individual and collective interests. We apply a transdisciplinary system approach—integrating the perspectives of ecologists, evolutionary biologists and agronomists into a social science theory of social dilemmas—to four landscape-scale weed management challenges: (i) achieving plant biosecurity, (ii) preventing weed seed contamination, (iii) maintaining herbicide susceptibility and (iv) sustainably using biological control. We describe how these four challenges exhibit characteristics of ‘public good problems’, wherein effective weed management requires the active contributions of multiple actors, while benefits are not restricted to these contributors. Adequate solutions to address these public good challenges often involve a subset of the eight design principles developed by Elinor Ostrom for ‘common pool social dilemmas’, together with design principles that reflect the public good nature of the problems. This paper is a call to action for scholars and practitioners to broaden our conceptualization and approaches to weed management problems. Such progress begins by evaluating the public good characteristics of specific weed management challenges and applying context-specific design principles to realize successful and sustainable weed management

Careers in context: An international study of career goals as mesostructure between societies’ career-related human potential and proactive career behavior

Careers exist in a societal context that offers both constraints and opportunities for career actors. Whereas most studies focus on proximal individual and/or organisational‐level variables, we provide insights into how career goals and behaviours are understood and embedded in the more distal societal context. More specifically, we operationalise societal context using the career‐related human potential composite and aim to understand if and why career goals and behaviours vary between countries. Drawing on a model of career structuration and using multilevel mediation modelling, we draw on a survey of 17,986 employees from 27 countries, covering nine of GLOBE's 10 cultural clusters, and national statistical data to examine the relationship between societal context (macrostructure building the career‐opportunity structure) and actors' career goals (career mesostructure) and career behaviour (actions). We show that societal context in terms of societies' career‐related human potential composite is negatively associated with the importance given to financial achievements as a specific career mesostructure in a society that is positively related to individuals' proactive career behaviour. Our career mesostructure fully mediates the relationship between societal context and individuals' proactive career behaviour. In this way, we expand career theory's scope beyond occupation‐ and organisation‐related factors

Genetically determined height and coronary artery disease.

BACKGROUND: The nature and underlying mechanisms of an inverse association between adult height and the risk of coronary artery disease (CAD) are unclear. METHODS: We used a genetic approach to investigate the association between height and CAD, using 180 height-associated genetic variants. We tested the association between a change in genetically determined height of 1 SD (6.5 cm) with the risk of CAD in 65,066 cases and 128,383 controls. Using individual-level genotype data from 18,249 persons, we also examined the risk of CAD associated with the presence of various numbers of height-associated alleles. To identify putative mechanisms, we analyzed whether genetically determined height was associated with known cardiovascular risk factors and performed a pathway analysis of the height-associated genes. RESULTS: We observed a relative increase of 13.5% (95% confidence interval [CI], 5.4 to 22.1; P<0.001) in the risk of CAD per 1-SD decrease in genetically determined height. There was a graded relationship between the presence of an increased number of height-raising variants and a reduced risk of CAD (odds ratio for height quartile 4 versus quartile 1, 0.74; 95% CI, 0.68 to 0.84; P<0.001). Of the 12 risk factors that we studied, we observed significant associations only with levels of low-density lipoprotein cholesterol and triglycerides (accounting for approximately 30% of the association). We identified several overlapping pathways involving genes associated with both development and atherosclerosis. CONCLUSIONS: There is a primary association between a genetically determined shorter height and an increased risk of CAD, a link that is partly explained by the association between shorter height and an adverse lipid profile. Shared biologic processes that determine achieved height and the development of atherosclerosis may explain some of the association. (Funded by the British Heart Foundation and others.).Supported by the British Heart Foundation, the United Kingdom National Institute for Health Research, the European Union project CVgenes@target, and a grant from the Leducq Foundation.This is the final published version. It first appeared at http://www.nejm.org/doi/full/10.1056/NEJMoa1404881