An evaluation of the use of concentrators for domiciliary oxygen supply for less than 8 h day−1

AbstractSince their introduction in 1985, oxygen concentrators have only been recommended when domiciliary oxygen is used for over 8 h day−1. Subsequent changes in the prices of oxygen merit a reappraisal of the prescribing of concentrators and cylinders when oxygen is used for less than 8 h day−1.Twenty-six patients in two health districts who used oxygen for less than 8 h day−1 completed a crossover study in which each group received oxygen from each source for consecutive 3-month periods. The patients were visited at home before and during the study, and on each visit they completed a questionnaire asking about their use of oxygen, how acceptable they found the two sources and about several dimensions of their quality of life. The theoretical minimum cost of cylinder supply, the actual cost of cylinder supply and the average concentrator costs were assessed.The patients found the concentrators to be more acceptable, more useful and less obtrusive than cylinders. They used more oxygen in more rooms of the home during treatment with concentrators, and there were improvements in the quality-of-life measurements. The costing information showed that, both in theory and in practice, oxygen concentrators are cheaper than cylinders when oxygen is used for more than about 1·4 h day−1.These results suggest that the provisions for the supply of domiciliary oxygen should be reviewed and that concentrators should be recommended for patients who use more than around 1·4 h day−1

An analogue of the Magnus problem for associative algebras

We prove an analogue of the Magnus theorem for associative algebras without unity over arbitrary fields. Namely, if an algebra is given by n+k generators and k relations and has an n-element system of generators, then this algebra is a free algebra of rank n

Bayesian algorithms for recovering structure from single-particle diffraction snapshots of unknown orientation: a comparison

The advent of X-ray Free Electron Lasers promises the possibility to determine the structure of individual particles such as microcrystallites, viruses and biomolecules from single-shot diffraction snapshots obtained before the particle is destroyed by the intense femtosecond pulse. This program requires the ability to determine the orientation of the particle giving rise to each snapshot at signal levels as low as ~10-2 photons/pixel. Two apparently different approaches have recently demonstrated this capability. Here we show they represent different implementations of the same fundamental approach, and identify the primary factors limiting their performance.Comment: 10 pages, 2 figure

Self-management strategies of cancer survivors: who does what and why? A mixed methods study

This thesis examined self-management (SM) strategies of cancer survivors from pre-diagnosis, through treatment and into survivorship. A healthcare definition of SM as a lifestyle modifying behaviour potentially impacting on cancer survivors’ health, wellbeing and quality of life (QoL) was given. Due to a lack of existing literature, a systematic review and meta-analyses investigating whether complementary and alternative medicine (CAM) improves cancer survivors’ QoL was undertaken, finding moderate to poor quality evidence of this. A mixed methods study explored SM patterns over time. The questionnaire study examined the prevalence and distribution of SM patterns, finding SM uptake was highest in survivorship. Subgroup analyses found SM uptake was highest in breast cancer and chemotherapy respondents, whilst correlation analysis revealed significant associations between SM uptake and both QoL and internal health locus of control (HLC), but none between SM uptake and work ability. The interview study explored how and why cancer survivors made decisions about incorporating SM practices into their daily lives. The concept of normality in survivorship emerged, with cancer survivors assembling a new health-related normality to adapt to their new lives post-cancer. A theoretical framework proposed that cancer survivors use SM as a supportive mechanism to attain their new health-related normality

Sleep and Circadian Rhythm Regulation in Early Parkinson Disease

Importance: Sleep disturbances are recognized as a common nonmotor complaint in Parkinson disease but their etiology is poorly understood. Objective: To define the sleep and circadian phenotype of patients with early-stage Parkinson disease. Design, Setting, and Participants: Initial assessment of sleep characteristics in a large population-representative incident Parkinson disease cohort (N=239) at the University of Cambridge, England, followed by further comprehensive case-control sleep assessments in a subgroup of these patients (n=30) and matched controls (n=15). Main Outcomes and Measures: Sleep diagnoses and sleep architecture based on polysomnography studies, actigraphy assessment, and 24-hour analyses of serum cortisol, melatonin, and peripheral clock gene expression (Bmal1, Per2, and Rev-Erbα). Results: Subjective sleep complaints were present in almost half of newly diagnosed patients and correlated significantly with poorer quality of life. Patients with Parkinson disease exhibited increased sleep latency (P = .04), reduced sleep efficiency (P = .008), and reduced rapid eye movement sleep (P = .02). In addition, there was a sustained elevation of serum cortisol levels, reduced circulating melatonin levels, and altered Bmal1 expression in patients with Parkinson disease compared with controls. Conclusions and Relevance: Sleep dysfunction seen in early Parkinson disease may reflect a more fundamental pathology in the molecular clock underlying circadian rhythms

Extraction of platinum metals during procssing of chromium ores from dunnite deposits

Currently, the main raw materials sources of platinum group metals in Russia are complex sulfide copper-nickel ores of the Taimyr region and placer deposits. However, in view of the inevitable loss of platinum metals during the metallurgical processing of initial ores and the deterioration of the quality of ore raw materials, along with a decrease in the share of platinum mining from placers, there is a need to look for new non-traditional sources of platinum group metals. Dunnites of the Middle Urals are promising platinum-bearing raw materials. The use of the gravitational-magnetic processing of chromium ores of dunnite deposits makes it possible to identify a magnetic platinum-bearing concentrate with a high content of magnetite and platinum-iron alloys, they can be refined using chemical-metallurgical methods. This article presents the results of research of identifying peculiarities of technological behavior of chromium, iron and noble metals during mechanical processing of ledge chromium ore. The kinetic regularities of the sulfuric acid decomposition of magnetite are determined. Optimum technological parameters of sulfuric acid leaching of iron from magnetic products of chromium ore dressing are established. Based on the conducted studies, the PDF and PID for the complex processing of chromium ores of dunnite deposits is proposed, which ensures the production of a rich platinum-bearing concentrate and a high-quality chromite concentrate that meets the requirements of chemical production

Identities in upper triangular tropical matrix semigroups and the bicyclic monoid

We establish necessary and sufficient conditions for a semigroup identity to hold in the monoid of n x n upper triangular tropical matrices, in terms of equivalence of certain tropical polynomials. This leads to an algorithm for checking whether such an identity holds, in time polynomial in the length of the identity and size of the alphabet. It also allows us to answer a question of Izhakian and Margolis, by showing that the identities which hold in the monoid of upper triangular tropical matrices are exactly the same as those which hold in the bicyclic monoid. Our results extend to a broader class of “chain structured tropical matrix semigroups”; we exhibit a faithful representation of the free monogenic inverse semigroup within such a semigroup, which leads also to a representation by upper triangular tropical matrices