phi-meson production in proton-antiproton annihilation

Apparent channel-dependent violations of the OZI rule in nucleon-antinucleon annihilation reactions are discussed in the presence of an intrinsic strangeness component in the nucleon. Admixture of strange-antistrange quark pairs in the nucleon wave function enables the direct coupling to the phi-meson in the annihilation channel without violating the OZI rule. Three forms are considered in this work for the strangeness content of the proton wave function, namely, the uud cluster with a strange-antistrange sea quark component, kaon-hyperon clusters based on a simple chiral quark model, and the pentaquark picture. Nonrelativistic quark model calculations reveal that the strangeness magnetic moment and the strangeness contribution to the proton spin from the first two models are consistent with recent experimental data. For the third model, the uuds subsystem with the configurations FS[31]F[211]S[22] and FS[31]F[31]S[22] leads to negative values for the strangeness magnetic moment and the strangeness contribution to the proton spin. With effective quark line diagrams incorporating the 3P0 quark model we give estimates for the branching ratios of the proton-antiproton annihilation reactions at rest to two mesons. Results for the branching ratios of phi-meson production from atomic proton-antiproton s-wave states are for the first and third model found to be strongly channel dependent, in good agreement with measured rates.Comment: 12 pages, 1 figur

Effective natural ventilation in modern apartment buildings

This paper addresses the challenge of evaluating for natural ventilation in modern apartment buildings. A number of natural ventilation design rules of thumb from published literature are listed. Their incorporation into one code for Australia (the Residential Flat Design Code, or RFDC) and India (the National Building Code, or NBC), in relation to apartment buildings is examined. Practical limitations to converting these rules of thumb into effective natural ventilation systems for apartment building designs are discussed. Apartment designs in the moderate locations of Sydney, Australia and Bengaluru, India are also reviewed to assess their effectiveness for natural ventilation. Simulation analysis presented indicate large energy savings are possible if apartments are retrofitted/designed to the proposed code requirements and designs compliant with thumb rules are capable of delivering effective natural ventilation if users choose to operate the apartment in “free running mode” during times when the outside dry bulb temperatures lie in an appropriate band. The paper also discusses how sub-optimal design solutions, affluence and adaptation to more stringent thermal conditions can negate the potential for natural ventilation and calls for proactive efforts to maintain climate responsive design standards and education/policy to encourage the benefits of natural ventilation over airconditioning

β-Lactoglobulin-linoleate complexes: In vitro digestion and the role of protein in fatty acids uptake

peer-reviewedThe dairy protein β-lactoglobulin (BLG) is known to bind fatty acids such as the salt of the essential longchain fatty acid linoleic acid (cis,cis-9,12-octadecadienoic acid, n-6, 18:2). The aim of the current study was to investigate how bovine BLG-linoleate complexes, of various stoichiometry, affect the enzymatic digestion of BLG and the intracellular transport of linoleate into enterocyte-like monolayers. Duodenal and gastric digestions of the complexes indicated that BLG was hydrolyzed more rapidly when complexed with linoleate. Digested as well as undigested BLG-linoleate complexes reduced intracellular linoleate transport as compared with free linoleate. To investigate whether enteroendocrine cells perceive linoleate differently when part of a complex, the ability of linoleate to increase production or secretion of the enteroendocrine satiety hormone, cholecystokinin, was measured. Cholecystokinin mRNA levels were different when linoleate was presented to the cells alone or as part of a protein complex. In conclusion, understanding interactions between linoleate and BLG could help to formulate foods with targeted fatty acid bioaccessibility and, therefore, aid in the development of food matrices with optimal bioactive efficacyS. Le Maux is currently supported by a Teagasc Walsh Fellowship and the Department of Agriculture, Fisheries and Food (FIRM project 08/RD/TMFRC/650). We also acknowledge funding from IRCSET-Ulysses Travel Grant

Phylogeny and Geographic History of Annonaceae

Whereas Takhtajan and Smith situated the origin of angiosperms between Southeast Asia and Australia, Walker and Le Thomas emphasized the concentration of primitive pollen types of Annonaceae in South America and Africa, suggesting instead a Northern Gondwanan origin for this family of primitive angiosperms. A cladistic analysis of Annonaceae shows a basal split of the family into Anaxagorea, the only genus with an Asian and Neotropical distribution, and a basically African and Neotropical line that includes the rest of the family. Several advanced lines occur in both Africa and Asia, one of which reaches Australia. This pattern may reflect the following history: (a) disjunction of Laurasian (Anaxagorea) and Northern Gondwanan lines in the Early Cretaceous, when interchanges across the Tethys were still easy and the major lines of Magnoliidae are documented by paleobotany; (b) radiation of the Northern Gondwanan line during the Late Cretaceous, while oceanic barriers were widening; (c) dispersal of African lines into Laurasia due to northward movement of Africa and India in the Early Tertiary, attested by the presence of fossil seeds of Annonaceae in Europe, and interchanges between North and South America at the end of the Tertiary.Alors que Takhtajan et Smith situaient l'origine des Angiospermes entre le Sud-Est asiatique et l'Australie. Walker et Le Thomas ont souligné la concentration des types polliniques primitifs d'Annonaceae en Amérique du Sud et en Afrique, laissant plutôt supposer une origine nord-gondwanienne pour cette famille d'Angiospermes primitives. Une analyse cladistique des Annonaceae révèle une division basale de la famille en Anaxagorea, seul genre de répartition asiatique et néotropicale, et une lignée fondamentalement africaine et néotropicale qui comprend le reste de la famille. Plusieurs lignées évoluées sont partagées entre l'Afrique et l'Asie, dont une atteint l'Australie. Ce schéma pourrait traduire l'histoire suivante : (a) la disjonction des lignées laurasienne (Anaxagorea) et nord-gondwanienne au Crétacé inférieur, alors que les échanges à travers la Téthys étaient encore faciles et que les grandes lignées de Magnoliidae sont établies par la paléobotanique; (b) la radiation de la lignée nord-gondwanienne pendant le Crétacé supérieur, lorsque les barrières océaniques s'élargissaient; (c) la dispersion de lignées africaines en Laurasie due au mouvement de l'Afrique et de l'Inde vers le nord au début du Tertiaire, attestée par la présence de graines fossiles d'Annonaceae en Europe, et des échanges entre l'Amérique du Nord et l'Amérique du Sud à la fin du Tertiaire.Wàhrend Takhtajan und Smith den Ursprung der Angiospermen zwischen Sùdostasien und Australien ansiedelten. haben Walker und Le Thomas die Konzentration primitiver Pollen-Typen von Annonaceae in Sùdamerika und Afrika hervorgehoben und so stattdessen einen Ursprung in Nord-Gondwanaland fur dièse Familie primitiver Angiospermen vorgeschlagen. Eine kladistische Analyse der Annonaceae zeigt eine Basis-Aufspaltung der Familie in Anaxagorea. die einzige Gattung mit asiatischer und neotropischer Verteilung und in eine grundsâtzlich afrikanische und neotropische Linie, welche den Rest der Familie einschliesst. Mehrere entwickelte Linien treten sowohl in Afrika wie Asien auf und eine davon erreicht Australien. Dies Schema kônnte die folgende Geschichte spiegeln: (a) Trennung der laurasischen (Anaxagorea) und der Nord-Godwanaland-Linien in derfrùhen Kreidezeit, zu einer Zeit als der Austausch ùber das Tethys noch einfach war und die Hauptlinien von Magnoliidae durch die Paieobotanik dokumentiert sind; (b) Radiation der Nord-Gondwanaland-Linie wàhrend der spâten Kreidezeit, als die Ozeanbarrieren sich verbreiterten; (c) Verbreitung der afrikanischen Linie ùber Laurasia aufgrund der Nordwàrts-Verschiebung von Afrika und Indien im frùhen Tertiâr, welche durch das Vorkommen fossiler Samen von Annonaceae in Europa bezeugt wird, und Austausch zwischen Nord- und Sùdamerika am Ende des Tertiârs

Infrared point source variability between the Spitzer and MSX surveys of the Galactic mid-plane

We present a list of 552 sources with suspected variability, based on a comparison of mid-infrared photometry from the GLIMPSE I and MSX surveys, which were carried out nearly a decade apart. We were careful to address issues such as the difference in resolution and sensitivity between the two surveys, as well as the differences in the spectral responses of the instruments. We selected only sources where the IRAC 8.0 and MSX 8.28 micron fluxes differ by more than a factor of two, in order to minimize contamination from sources where the difference in fluxes at 8 micron is due to a strong 10 micron silicate feature. We present a subset of 40 sources for which additional evidence suggests variability, using 2MASS and MIPSGAL data. Based on a comparison with the variability flags in the IRAS and MSX Point-Source Catalogs we estimate that at least a quarter of the 552 sources, and at least half of the 40 sources are truly variable. In addition, we tentatively confirm the variability of one source using multi-epoch IRAS LRS spectra. We suggest that most of the sources in our list are likely to be Asymptotic Giant Branch stars.Comment: 47 pages, 12 Figures, 3 Tables, accepted for publication in A

Effects of wall compliance on the laminar–turbulent transition of torsional Couette flow

Torsional Couette flow between a rotating disk and a stationary wall is studied experimentally. The surface of the disk is either rigid or covered with a compliant coating. The influence of wall compliance on characteristic flow instabilities and on the laminar–turbulent flow transition is investigated. Data obtained from analysing flow visualizations are discussed. It is found that wall compliance favours two of the three characteristic wave patterns associated with the transition process and broadens the parameter regime in which these patterns are observed. The results for the effects of wall compliance on the third pattern are inconclusive. However, the experiments indicate that the third pattern is not a primary constituent of the laminar–turbulent transition process of torsional Couette flow

Measurement of overall insecticidal effects in experimental hut trials

BACKGROUND: The 'overall insecticidal effect' is a key measure used to evaluate public health pesticides for indoor use in experimental hut trials. It depends on the proportion of mosquitoes that are killed out of those that enter the treated hut, intrinsic mortality in the control hut, and the ratio of mosquitoes entering the treatment hut to those entering the control hut. This paper critically examines the way the effect is defined, and discusses how it can be used to infer effectiveness of intervention programmes. FINDINGS: The overall insecticidal effect, as defined by the World Health Organization in 2006, can be negative when deterrence from entering the treated hut is high, even if all mosquitoes that enter are killed, wrongly suggesting that the insecticide enhances mosquito survival. Also in the absence of deterrence, even if the insecticide kills all mosquitoes in the treatment hut, the insecticidal effect is less than 100%, unless intrinsic mortality is nil. A proposed alternative definition for the measurement of the overall insecticidal effect has the desirable range of 0 to 1 (100%), provided mortality among non-repelled mosquitoes in the treated hut is less than the corresponding mortality in the control hut. This definition can be built upon to formulate the coverage-dependent insecticidal effectiveness of an intervention programme. Coverage-dependent population protection against feeding can be formulated similarly. CONCLUSIONS: This paper shows that the 2006 recommended quantity for measuring the overall insecticidal effect is problematic, and proposes an alternative quantity with more desirable propertie

Block Coordinate Descent for Sparse NMF

Nonnegative matrix factorization (NMF) has become a ubiquitous tool for data analysis. An important variant is the sparse NMF problem which arises when we explicitly require the learnt features to be sparse. A natural measure of sparsity is the L$_0$ norm, however its optimization is NP-hard. Mixed norms, such as L$_1$/L$_2$ measure, have been shown to model sparsity robustly, based on intuitive attributes that such measures need to satisfy. This is in contrast to computationally cheaper alternatives such as the plain L$_1$ norm. However, present algorithms designed for optimizing the mixed norm L$_1$/L$_2$ are slow and other formulations for sparse NMF have been proposed such as those based on L$_1$ and L$_0$ norms. Our proposed algorithm allows us to solve the mixed norm sparsity constraints while not sacrificing computation time. We present experimental evidence on real-world datasets that shows our new algorithm performs an order of magnitude faster compared to the current state-of-the-art solvers optimizing the mixed norm and is suitable for large-scale datasets