Information techniques for irrigation systems: Selected proceedings of the Second International Network Meeting on Information Techniques for Irrigation Systems held in Lahore/Bahawalnagar, Pakistan, 5-8 December 1994

Irrigation management / Irrigation systems / Decision support tools / Decision making / Information systems / Computer techniques / Models / Water management / Malaysia / Pakistan / Sri Lanka

Prevalence and causes of blindness and visual impairment in Muyuka: a rural health district in South West Province, Cameroon.

AIM: To estimate the prevalence and causes of blindness and visual impairment in the population aged 40 years and over in Muyuka, a rural district in the South West Province of Cameroon. METHODS: A multistage cluster random sampling methodology was used to select 20 clusters of 100 people each. In each cluster households were randomly selected and all eligible people had their visual acuity (VA) measured by an ophthalmic nurse. Those with VA <6/18 were examined by an ophthalmologist. RESULTS: 1787 people were examined (response rate 89.3%). The prevalence of binocular blindness was 1.6% (95% CI: 0.8% to 2.4%), 2.2% (1.% to 3.1%) for binocular severe visual impairment, and 6.4% (5.0% to 7.8%) for binocular visual impairment. Cataract was the main cause of blindness (62.1%), severe visual impairment (65.0%), and visual impairment (40.0%). Refractive error was an important cause of severe visual impairment (15.0%) and visual impairment (22.5%). The cataract surgical coverage for people was 55% at the <3/60 level and 33% at the <6/60 level. 64.3% of eyes operated for cataract had poor visual outcome (presenting VA<6/60). CONCLUSIONS: Strategies should be developed to make cataract services affordable and accessible to the population in the rural areas. There is an urgent need to improve the outcome of cataract surgery. Refractive error services should be provided at the community level

Deterministic Threshold Queries of Distributed Data Structures

Abstract. Convergent replicated data types, or CvRDTs, are latticebased data structures for enforcing the eventual consistency of replicated objects in a distributed system. Although CvRDTs are provably eventually consistent, queries of CvRDTs nevertheless allow inconsistent intermediate states of replicas to be observed; and although in practice, many systems allow a mix of eventually consistent and strongly consistent queries, CvRDTs only support the former. Taking inspiration from our previous work on LVars for deterministic parallel programming, we show how to extend CvRDTs to support deterministic, strongly consistent queries using a mechanism called threshold queries. The threshold query technique generalizes to any lattice, and hence any CvRDT, and allows deterministic observations to be made of replicated objects before the replicas ’ states have converged

Performances du goutte à goutte enterré pour l'irrigation de jeunes palmiers dattiers

Dans les zones oasiennes, les ressources en eau de surface deviennent de plus en plus rares et les ressources en eau souterraines sont souvent surexploitées et de mauvaise qualité avec une salinité élevée. L'économie de l'eau et sa préservation est devenue par conséquent un impératif pour la durabilité des oasis. Si l'irrigation localisée est actuellement préconisée au Maroc pour l'économie de l'eau, son utilisation dans les régions subdésertiques ne permet pas de réduire les taux élevés des pertes par évaporation. Une alternative à ce système serait l'utilisation de la technique d'irrigation souterraine au moyen d'émetteurs débitant l'eau à des taux généralement similaire à l'irrigation goutte à goutte de surface. L'irrigation souterraine étant une technique très récemment introduite au Maroc, une meilleure compréhension dans les conditions locales du processus d'infiltration, et son impact sur la croissance d'une plante comme le palmier dattier s'avère nécessaire. Cette étude vise à contribuer à l'amélioration de l'efficience de l'utilisation de l'eau en testant la performance du système d'irrigation souterraine dans un contexte où l'eau est une ressource limitée. L'objectif de ce travail de recherche est l'évaluation des performances en conditions arides d'un système d'irrigation au goutte à goutte enterré sur jeunes palmiers dattiers en comparaison avec le goutte à goutte de surface. En préambule à ce travail, on s'attachera à déterminer une méthode adaptée à la mesure du débit d'un goutteur enterré. Un essai expérimental visant à caractériser les performances respectives du goutte à goutte de surface et du goutte à goutte enterré sur de jeunes palmiers dattiers a été mis en place chez un agriculteur de la région d'Erfoud (Province d'Errachidia, Sud-Est du Maroc). La mesure du débit pour évaluer l'uniformité de l'application a été faite selon deux méthodes: une mesure du débit des goutteurs en ''hors sol'' et une autre en présence du sol. Cette dernière méthode nous a aussi permis d'estimer les pertes par évaporation pour les deux techniques d'irrigation. En outre, Pour pouvoir comparer l'effet des deux modes d'irrigation, on a choisi des plantes au hasard pour chaque type d'irrigation pour le suivi de certains paramètres agronomiques (nombres cumulés de palmes et développement racinaire). L'expérimentation présente une uniformité de distribution de l'ordre de 88%; qualifiée de satisfaisante pour l'irrigation goutte à goutte souterraine alors qu'elle est de l'ordre de 80% pour l'irrigation goutte à goutte de surface. Les résultats obtenus montrent aussi une augmentation du développement racinaire et du nombre de palmes, ainsi qu'une économie d'eau considérable suite à la diminution des pertes par évaporation par rapport à la méthode d'irrigation goutte à goutte classique. Les résultats de cette étude ont montré que l'irrigation goutte à goutte souterraine est une technique efficiente susceptible de contribuer à une irrigation durable dans les zones arides. (Résumé d'auteur

On the Lawrence–Doniach and Anisotropic Ginzburg–Landau Models for Layered Superconductors

The authors consider two models, the Lawrence-Doniach and the anisotropic Ginzburg-Landau models for layered superconductors such as the recently discovered high-temperature superconductors. A mathematical description of both models is given and existence results for their solution are derived. The authors then relate the two models in the sense that they show that as the layer spacing tends to zero, the Lawrence-Doniach model reduces to the anisotropic Ginzburg- Landau model. Finally, simplified versions of the models are derived that can be used to accurately simulate high-temperature superconductors

Searching for observational studies: what does citation tracking add to PubMed? A case study in depression and coronary heart disease

BACKGROUND: PubMed is the most widely used method for searches of the medical literature, but fails to identify many relevant articles. Electronic citation tracking offers an alternative search method. METHODS: Articles investigating the role of depression in the aetiology and prognosis of coronary heart disease were sought through two methods: a) PubMed, and b) citation tracking where Science Citation Index was searched for all articles which cited ("forward citation tracking") or were cited by ("backward citation tracking") any of the articles in an index review. The number and quality of eligible articles identified by the two methods were compared. RESULTS: 50 articles that were not already included in the index review met our inclusion criteria; 11 were identified through Science Citation Index alone, 8 through PubMed alone, and 31 through both methods. Articles identified by Science Citation Index alone were published in higher impact factor journals, were larger and were less likely to show a positive association. CONCLUSION: Science Citation Index identified more eligible articles than PubMed, and these differed qualitatively. Failing to use citation tracking in a systematic review of observational studies may result in bias

Phonon Coherence and New Set of Sidebands in Phonon-Assisted Photoluminescence

We investigate excitonic polaron states comprising a local exciton and phonons in the longitudinal optical (LO) mode by solving the Schr\"{o}dinger equation. We derive an exact expression for the ground state (GS), which includes multi-phonon components with coefficients satisfying the Huang-Rhys factors. The recombination of GS and excited polaron states gives one set of sidebands in photoluminescence (PL): the multi-phonon components in the GS produce the Stokes lines and the zero-phonon components in the excited states produce the anti-Stokes lines. By introducing the mixing of the LO mode and environal phonon modes, the exciton will also couple with the latter, and the resultant polaron states result in another set of phonon sidebands. This set has a zero-phonon line higher and wider than that of the first set due to the tremendous number of the environal modes. The energy spacing between the zero-phonon lines of the first and second sets is proved to be the binding energy of the GS state. The common exciton origin of these two sets can be further verified by a characteristic Fano lineshape induced by the coherence in the mixing of the LO and the environal modes.Comment: 5 pages, 3 figures 1 figure (fig. 1) replaced 1 figure (fig. 2) remove