154 research outputs found

    A Fermi Surface study of Ba1−x_{1-x}Kx_{x}BiO3_{3}

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    We present all electron computations of the 3D Fermi surfaces (FS's) in Ba1−x_{1-x}Kx_{x}BiO3_{3} for a number of different compositions based on the selfconsistent Korringa-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) approach for incorporating the effects of Ba/K substitution. By assuming a simple cubic structure throughout the composition range, the evolution of the nesting and other features of the FS of the underlying pristine phase is correlated with the onset of various structural transitions with K doping. A parameterized scheme for obtaining an accurate 3D map of the FS in Ba1−x_{1-x}Kx_{x}BiO3_{3} for an arbitrary doping level is developed. We remark on the puzzling differences between the phase diagrams of Ba1−x_{1-x}Kx_{x}BiO3_{3} and BaPbx_{x}Bi1−x_{1-x}O3_{3} by comparing aspects of their electronic structures and those of the end compounds BaBiO3_{3}, KBiO3_3 and BaPbO3_3. Our theoretically predicted FS's in the cubic phase are relevant for analyzing high-resolution Compton scattering and positron-annihilation experiments sensitive to the electron momentum density, and are thus amenable to substantial experimental verification.Comment: 12 pages, 7 figures, to appear in Phys. Rev.

    Characterization and quantification of postharvest losses of apple fruit stored under commercial conditions.

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    The objectives of this study were to characterize and quantify postharvest losses of apples under commercial conditions in Santa Catarina state, Brazil. Two experiments were conducted using ?Gala? and ?Fuji? apples. The first experiment was to characterize and quantify the most important causes of loss of fruit treated or not treated with 1-methylcyclopropene (1-MCP) then held in controlled atmosphere (CA) storage. This experiment was conducted in commercial storage facilities from 2007 to 2010. In each year, 10 samples of ≈380 kg each for ?Gala? and 400 kg each for ?Fuji? were collected from bins of commercially harvested fruit from each of 15 ?Gala? and 17 ?Fuji? orchards. Half of the samples from each orchard were treated with 1-MCP at harvest. Fruit were stored in CA, at 0.7 °C, for 150 to 300 days. After storage, one subsample of 100 disorder-free apples were selected from each sample and held at 22 °C for 7 days to simulate shelf-life conditions. The fruit were analyzed after CA storage and shelf life for the incidence of disorders. The second experiment was conducted in 2011 to identify the main fungi causing decay during storage. In this study, apples were stored in 10 commercial CA storage rooms at 0.7 °C for 180 to 240 days. After storage, fruit with decay symptoms were collected at the commercial sorting line. A total of 10 samples of 100 decayed apples were taken throughout the sorting period for each cultivar and storage room. The fungal decays were identified by visual symptoms on each fruit. Total apple losses during storage varied from 3.9% to 12.1% for ?Gala? and 6.6% to 8.4% for ?Fuji?, depending on the year and 1-MCP treatment. During storage, deterioration caused by fungal decay was ≈60% and 80% of total losses for ?Gala? and ?Fuji?, respectively. During shelf life, additional losses caused by fungal decay ranged from 8.4% to 17.6% for ?Gala? and 12.4% to 27.2% for ?Fuji?, depending on the year. Senescent breakdown and superficial scald were the major physiological disorders. 1-MCP treatment had no effect on losses due to decay. Bull?s-eye rot, blue mold, gray mold, and alternaria rot were the most prevalent fungal decay symptoms, accounting for 52%, 27%, 9% and 10% of ?Gala? losses and 42%, 25%, 18% and 5% of ?Fuji? losses, respectively. Sources of variability for losses among years and orchards is discussed

    Regional actorness and interregional relations:ASEAN, the EU and Mercosur

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    The European Union (EU) has a long tradition of interregional dialogue mechanisms with other regional organisations and is using these relations to project its own model of institutionalised actorness. This is partly motivated by the emerging actorness of the EU itself, which benefits from fostering capable regional counterparts in other parts of the world. This article advances the argument that actorness, which we conceptualise in terms of institutions, recognition and identity, is a relational concept, dependent on context and perception. Taking the Association of Southeast Asian Nations (ASEAN) and the Common Market of the South (Mercosur) and their relations with the EU as case studies, this article demonstrates that the actorness capabilities of all three organisations have been enhanced as result of ASEAN-EU and Mercosur-EU relations. However, there are clear limits to the development of the three components of regional actorness and to the interregional relations themselves. These limits stem both from the type of interregionalism at play and from the different regional models the actors incorporate. While there is evidence of institutional enhancement in ASEAN and Mercosur, these formal changes have been grafted on top of firmly entrenched normative underpinnings. Within the regional organisations, interactions with the EU generate centrifugal forces concerning the model to pursue, thus limiting their institutional cohesion and capacity. In addition, group-to-group relations have reinforced ASEAN and Mercosur identities in contrast to the EU. The formation of such differences has narrowed the scope of EU interregionalism despite the initial success of improved regional actorness

    The observational clinical registry (cohort design) of the European Reference Network on Rare Adult Solid Cancers: The protocol for the rare head and neck cancers

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    Care for head and neck cancers is complex in particular for the rare ones. Knowledge is limited and histological heterogeneity adds complexity to the rarity. There is a wide consensus that to support clinical research on rare cancer, clinical registries should be developed within networks specializing in rare cancers. In the EU, a unique opportunity is provided by the European Reference Networks (ERN). The ERN EURACAN is dedicated to rare adults solid cancers, here we present the protocol of the EURACAN registry on rare head and neck cancers (ClinicalTrials.gov Identifier: NCT05483374). Study design Registry-based cohort study including only people with rare head and neck cancers. Objectives 1.To help describe the natural history of rare head and neck cancers; 2.To evaluate factors that influence prognosis; 3.To assess treatment effectiveness; 4.To measure indicators of quality of care. Methods Settings and participants It is an hospital based registry established in hospitals with expertise in head and neck cancers. Only adult patients with epithelial tumours of nasopharynx; nasal cavity and paranasal sinuses; salivary gland cancer in large and small salivary glands; and middle ear will be included in the registry. This registry won t select a sample of patients. Each patient in the facility who meets the above mentioned inclusion criteria will be followed prospectively and longitudinally with follow-up at cancer progression and / or cancer relapse or patient death. It is a secondary use of data which will be collected from the clinical records. The data collected for the registry will not entail further examinations or admissions to the facility and/or additional appointments to those normally provided for the patient follow-up. Variables Data will be collected on patient characteristics (eg. patient demographics, lifestyle, medical history, health status); exposure data (eg. disease, procedures, treatments of interest) and outcomes (e.g. survival, progression, progression-free survival, etc.). In addition, data on potential confounders (e.g. comorbidity; functional status etc.) will be also collected. Statistical methods The data analyses will include descriptive statistics showing patterns of patients and cancers variables and indicators describing the quality of care. Multivariable Cox s proportional hazards model and Hazard ratios (HR) for all-cause or cause specific mortality will be used to determine independent predictors of overall survival, recurrence etc. Variables to include in the multivariable regression model will be selected based on the results of univariable analysis. The role of confounding or effect modifiers will be evaluated using stratified analysis or sensitivity analysis. To assess treatment effectiveness, multivariable models with propensity score adjustment and progression-free survival will be performed. Adequate statistical (eg. marginal structural model) methods will be used if time-varying treatments/ confounders and confounding by indication (selective prescribing) will be present. Results The registry initiated recruiting in May 2022. The estimated completion date is December 2030 upon agreement on the achievement of all the registry objectives. As of October 2022, the registry is recruiting. There will be a risk of limited representativeness due to the hospital-based nature of the registry and to the fact that hospital contributing to the registry are expert centres for these rare cancers. Clinical Follow-up could also be an issue but active search of the life status of the patients will be guaranteed

    Thermal conductivity of high- T c superconductors

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    This paper reviews existing data on the thermal conductivity of high- T c superconductors. Included are discussions of pristine polycrystalline high- T c ceramics, single crystal specimens, and high- T c materials structurally modified by substitution or by radiation damage. The thermal conductivity of high- T c superconductors is compared with that of conventional superconductors, and dramatic differences are found between the two families. Mechanisms of thermal conductivity applicable to high- T c perovskites are discussed and implications for theories of high- T c superconductivity are noted.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45121/1/10948_2004_Article_BF00617463.pd
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