Optical observation of single spins in silicon.

The global quantum internet will require long-lived, telecommunications-band photon-matter interfaces manufactured at scale1. Preliminary quantum networks based on photon-matter interfaces that meet a subset of these demands are encouraging efforts to identify new high-performance alternatives2. Silicon is an ideal host for commercial-scale solid-state quantum technologies. It is already an advanced platform within the global integrated photonics and microelectronics industries, as well as host to record-setting long-lived spin qubits3. Despite the overwhelming potential of the silicon quantum platform, the optical detection of individually addressable photon-spin interfaces in silicon has remained elusive. In this work, we integrate individually addressable 'T centre' photon-spin qubits in silicon photonic structures and characterize their spin-dependent telecommunications-band optical transitions. These results unlock immediate opportunities to construct silicon-integrated, telecommunications-band quantum information networks.

COVID-19 and the agri-food system in the United States and Canada.

Agri-food supply chains in North America have become remarkably efficient, supplying an unprecedented variety of items at the lowest possible cost. However, the initial stages of the COVID-19 pandemic and the near-total temporary loss of the foodservice distribution channel, exposed a vulnerability that many found surprising. Instead of continued shortages, however, the agri-food sector has since moved back to near normal conditions with prices and production levels similar to those typically observed in years prior to the pandemic. Ironically, the specialization in most food supply chains designed for "just-in-time" delivery to specific customers with no reserve capacity, which led to the initial disruptions, may have also been responsible for its rapid rebound. A common theme in assessing the impacts across the six commodities examined is the growing importance of understanding the whole supply chain. Over the longer term, a continuation of the pandemic could push the supply chain toward greater consolidation of firms and diversification of products given the increasing option value of maintaining flexibility. Other structural changes will be felt through input markets, most notably labour, as the trend toward greater automation will continue to accelerate as a response to meeting concerns about a consistent supply of healthy and productive workers. The economic fall out from the pandemic may lead to greater concentration in the sector as some firms are not able to survive the downturn and changes in consumer food buying behaviour, including movement toward online shopping and enhanced demand for attributes associated with resiliency, such as local. On the other hand, online shopping may provide opportunities for small producers and processors to shorten supply chains and reach customers directly. In the long term, COVID-19 impacts on global commerce and developing country production are more uncertain and could influence poverty reduction. While COVID-19's impacts on North American agriculture should have minimal effect on the Sustainable Development Goals (SDGs) through food prices, the ongoing global trends in trade and agribusiness accelerated by the pandemic are relevant for achievement of the SDGs.

Limitations in the inverse association between psychological resilience and depression in prostate cancer patients experiencing chronic physiological stress.

OBJECTIVE: To investigate the effect of chronic stress as measured in cortisol concentrations upon the association between psychological resilience (PR) and depression in prostate cancer (PCa) patients. METHODS: A total of 104 men with PCa completed inventories on PR, depression, and background factors, plus gave a sample of their saliva for cortisol assay. RESULTS: The inverse correlation between PR and depression was present only for PCa patients with low or moderate concentrations of salivary cortisol (when classified as more than 1.0 SD below the mean vs within 1.0 SD of the group mean) but not for those men whose cortisol was >1.0 SD from the group mean. Specific PR factors and behaviours that made the greatest contribution to depression were identified for the low and moderate cortisol groups. CONCLUSIONS: These results suggest that there are particular aspects of PR that are most strongly related to depression, but that PR's inverse association with depression may be absent in participants with extreme chronic physiological stress.

Comparing a genetic and a psychological factor as correlates of anxiety, depression, and chronic stress in men with prostate cancer.

PURPOSE: Some prostate cancer (PCa) patients become clinically anxious or depressed after diagnosis and treatment. Some also show the physiological signs of chronic stress. However, there are currently no data describing how these particular patients might be identified at intake. This study tested the individual and combined predictive power of a psychological factor and a genetic factor as potential predictors of anxiety, depression, and chronic stress in a sample of PCa patients. METHODS: Ninety-five PCa patients completed psychological inventories for anxiety, depression, and psychological resilience (PR) and also gave a saliva sample for cortisol and a mouthwash sample for genetic testing for the presence of the BDNF Val66Met polymorphism. RESULTS: High PR patients had significantly lower anxiety and depression than low PR patients, but showed no significant differences in their salivary cortisol. Carriers of the Met allele of the BDNF Val66Met polymorphism had significantly higher salivary cortisol concentrations than patients who did not carry this allele. CONCLUSIONS: Each of these two factors may provide valuable information regarding the vulnerability of PCa patients to anxiety, depression, or chronic stress. Suggestions are made for their inclusion in clinical settings.

The control of invasive species on private property with neighbor-to-neighbor spillovers.

Invasive pests cross property boundaries. Property managers may have private incentives to control invasive species despite not having sufficient incentive to fully internalize the external costs of their role in spreading the invasion. Each property manager has a right to future use of his own property, but his property may abut others' properties enabling spread of an invasive species. The incentives for a foresighted property manager to control invasive species have received little attention. We consider the efforts of a foresighted property manager who has rights to future use of a property and has the ability to engage in repeated, discrete control activities. We find that higher rates of dispersal, associated with proximity to neighboring properties, reduce the private incentives for control. Controlling species at one location provides incentives to control at a neighboring location. Control at neighboring locations are strategic complements and coupled with spatial heterogeneity lead to a weaker-link public good problem, in which each property owner is unable to fully appropriate the benefits of his own control activity. Future-use rights and private costs suggest that there is scope for a series of Coase-like exchanges to internalize much of the costs associated with species invasion. Pigouvian taxes on invasive species potentially have qualitatively perverse behavioral effects. A tax with a strong income effect (e.g, failure of effective revenue recycling) can reduce the value of property assets and diminish the incentive to manage insects on one's own property.

Modeling Product Choices in a Peer Network.

Consumers are uncertain about their preferences for innovative product attributes until the first trial. They search for information as a means of reducing uncertainty and improving the likelihood that they will be satisfied with their purchase. One way to receive information is through peer networks. As a peer network is often a priori unknown, we conduct an experiment to solicit self-reported peer nominations. We compare two mechanisms through which peer networks operate: Strength of social ties and perceived peer expertise, to draw inferences regarding consumers' preference reversal after exposure to peer recommendations. Our results indicate that perceived source expertise influences preferences while the closeness of social relationships has no statistically significant impact.

Design and rationale for evaluating salad bars and students' fruit and vegetable consumption: A cluster randomized factorial trial with objective assessments.

Building healthy fruit and vegetable (FV) consumption habits early in life is critical for primary prevention. However, U.S. youth do not come close to meeting national recommendations for FV intake. School-lunch salad bars are one of the most heavily promoted ways to meet FV guidelines. Contrary to popular belief, no rigorous randomized trials have examined whether salad bars increase students' FV consumption. This paper describes the design and rationale of a federally funded trial to evaluate whether introducing salad bars in elementary, middle, and high schools affects students' FV consumption and waste during lunch. A cluster factorial randomized trial will test new salad bars against waitlist controls, with and without an additional marketing intervention (N = 36 schools, N = 6804 students: n = 12 elementary, n = 12 middle and n = 12 high schools). Objective plate waste measurements of individual student's selection of FVs, consumption, and waste will be conducted using digital scales. Primary aim includes comparing FV consumption in schools without salad bars to those with new salad bars by grade level. Secondary aims include: a) whether FV marketing impacts the success of salad bars for FV consumption; b) whether salad bars differentially result in more FV waste compared to traditional serving methods; c) cost-benefit of using salad bars for consumption over traditional serving methods. When complete, this study stands to be one of the most definitive on the effectiveness of salad bars and contextual factors impacting their success. Findings will provide evidence for how to best spend limited federal dollars to improve FV intake in schools. Trial registration: ClinicalTrials.gov Identifier: NCT03283033 (date of registration: 9/14/2017).

A photonic platform for donor spin qubits in silicon.

Donor spins in silicon are highly competitive qubits for upcoming quantum technologies, offering complementary metal-oxide semiconductor compatibility, coherence (T2) times of minutes to hours, and simultaneous initialization, manipulation, and readout fidelities near ~99.9%. This allows for many quantum error correction protocols, which will be essential for scale-up. However, a proven method of reliably coupling spatially separated donor qubits has yet to be identified. We present a scalable silicon-based platform using the unique optical properties of "deep" chalcogen donors. For the prototypical 77Se+ donor, we measure lower bounds on the transition dipole moment and excited-state lifetime, enabling access to the strong coupling limit of cavity quantum electrodynamics using known silicon photonic resonator technology and integrated silicon photonics. We also report relatively strong photon emission from this same transition. These results unlock clear pathways for silicon-based quantum computing, spin-to-photon conversion, photonic memories, integrated single-photon sources, and all-optical switches.

Nutrient Demand in Food Away from Home.

Food away from home (FAFH) and, specifically fast food, has been targeted by academics and public policy officials alike as a major contributor to the obesity epidemic. Criticized as high in energy, fat and sugars, the implication is that consumers demand the combination of nutrients in FAFH in excess. If market-based policies intended to correct the perceived market failure in nutrient demand are to be successful, information on nutrient elasticities is required. Moreover, co-dependent relationships between nutrient intake and bioeconomic outcomes - obesity, physical activity and health status - are found to be important in the public health literature, but are not typically included in econometric studies of FAFH demand. Nutrients, however, do not have market prices. This study derives a set of implicit nutrient prices and estimates the elasticities of demand for nutrients in FAFH that takes into account the endogeneity of bioeconomic outcomes. Our estimation results show that fat is the only macro-nutrient that is elastic in demand, and all cross-price elasticities are small, so nutrient-based price policies may indeed be effective in modifying FAFH choices. Simulation results confirm this hypothesis, and also support the use of policies that subsidize positive health outcomes.

Characterization of stanniocalcin-1 receptors in the rainbow trout.

Mammalian stanniocalcin-1 (STC-1) is one of several ligands targeted to mitochondria. High affinity STC-1 receptors are present on the mitochondrial membranes of nephron cells, myocytes, and hepatocytes, to enable ligand sequestration within the matrix. However, STC-1 receptors have not been characterized in fish. Nor is it known if mitochondrial targeting occurs in fish. The aim of the study was to address these questions. Saturation binding assays were carried out to obtain estimates of K(D) and B(max). They revealed the presence of saturable, high-affinity receptors on both membranes and mitochondria of liver, muscle, and gill filament. In situ ligand binding (ISLB) was used to localize receptors at the histological level and revealed some unexpected findings. In cranium, for instance, receptors were found mainly in the cartilage matrix, as opposed to the chondrocytes. In brain, the majority of receptors were located on neuropil areas as opposed to neuronal cell bodies. In skeletal muscle, receptors were confined to periodic striations, tentatively identified as the Z lines. Receptors were even found on STC-1 producing corpuscles of Stannius cells, raising the possibility of there being an autocrine feedback loop or, perhaps, a soluble binding protein that is released with the ligand to regulate its bioavailability.

The cell cycle and DNA mismatch repair.

The DNA mismatch repair (MMR) pathway contributes to the fidelity of DNA synthesis and recombination by correcting mispaired nucleotides and insertion/deletion loops (IDLs). We have investigated whether MMR protein expression, activity, and subcellular location are altered during discrete phases of the cell cycle in mammalian cells. Two distinct methods have been used to demonstrate that although physiological MMR protein expression, mismatch binding, and nick-directed MMR activity within the nucleus are at highest levels during S phase, MMR is active throughout the cell cycle. Despite equal MMR nuclear protein concentrations in S and G(2) phases, mismatch binding and repair activities within G(2) are significantly lower, indicating a post-translational decrease in MMR activity specific to G(2). We further demonstrate that typical co-localization of MutSalpha to late S phase replication foci can be disrupted by 2 microM N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). This concentration of MNNG does not decrease ongoing DNA synthesis nor induce cell cycle arrest until the second cell cycle, with long-term colony survival decreased by only 24%. These results suggest that low level alkylation damage can selectively disrupt MMR proofreading activity during DNA synthesis and potentially increase mutation frequency within surviving cells.

Determination of deforestation rates of the world's humid tropical forests.

A recently completed research program (TREES) employing the global imaging capabilities of Earth-observing satellites provides updated information on the status of the world's humid tropical forest cover. Between 1990 and 1997, 5.8 +/- 1.4 million hectares of humid tropical forest were lost each year, with a further 2.3 +/- 0.7 million hectares of forest visibly degraded. These figures indicate that the global net rate of change in forest cover for the humid tropics is 23% lower than the generally accepted rate. This result affects the calculation of carbon fluxes in the global budget and means that the terrestrial sink is smaller than previously inferred.