288 research outputs found
K-Rational D-Brane Crystals
In this paper the problem of constructing spacetime from string theory is
addressed in the context of D-brane physics. It is suggested that the knowledge
of discrete configurations of D-branes is sufficient to reconstruct the motivic
building blocks of certain Calabi-Yau varieties. The collections of D-branes
involved have algebraic base points, leading to the notion of K-arithmetic
D-crystals for algebraic number fields K. This idea can be tested for D0-branes
in the framework of toroidal compactifications via the conjectures of Birch and
Swinnerton-Dyer. For the special class of D0-crystals of Heegner type these
conjectures can be interpreted as formulae that relate the canonical Neron-Tate
height of the base points of the D-crystals to special values of the motivic
L-function at the central point. In simple cases the knowledge of the
D-crystals of Heegner type suffices to uniquely determine the geometry.Comment: 36 page
Milied it-tajjeb
Ġabra ta’ poeżiji u proża li tinkludi: Imħabba taħt siġra ta’ V. Caruana – L-isptar tal-Gwardamanġa ta’ P. Mattew – Lourdes – il-Belt tal-Madonna ta’ Ġużè Chetcuti – Ja iblah, ma temminx? ta’ John C. Friggieri – Ħolma ta’ A. Cremona – Il-Milied it-tajjeb ta’ Ġużè Borg Pantalleresco.peer-reviewe
Deo Altissimo
Ġabra ta’ poeżiji u proża li tinkludi: Presepju ta’ Tfuliti ta’ Dun Karm – Lil Mikiel Anton Vassalli ta’ A. Cremona – Lil Rosario Briffa ta’ Giorgio Pisani – Rmied ta’ Dun Karm – L-Ewwel Tqarbina – L-Ewwel Quddiesa ta’ Dun Karm – Deo Altissimo ta’ C. V.N/
The variability of birth weight
The material for this study was obtained from the maternity records relating to single births occurring in Malta throughout 1965. In this year there were 5,719 total births; of these the sample studied covers 2,517 births (44.11 percent). The records were personally examined by one of the authors (Cremona, 1967) from St. Luke's Hospital Malta, from Maltese private Hospitals, and from the District Nursing Association. In Malta the mean birth weight for male babies is 3446g, and for female babies 3358g. The mean birth weight tends to increase with the mother's parity, and this trend continues even with the higher parities. The association between birth weight and rising maternal age remains uncertain. It is also probable that birth weight has a geographical determinant. Birth weight is a multifactorial product and cannot be very reliable as a clinical parameter. A new terminology is necessary to distinguish between three different groups of babies with low birth weights.peer-reviewe
Zn-doped titania nanoparticles as building blocks for solid foam filters of water and air via photocatalytic oxidation
Photocatalytic oxidation (PCO) could provide energy-efficient purification of water and air. Its efficacy is constrained mainly by limited photocatalytic activity and active surface. To address both, solid foams with hierarchic porous structures spanning multiple length-scales, stabilized by photocatalytic Zn-doped titania nanoparticles (NP) were synthesized and tested. The NP were characterized by SEM, EDS, DLS, XRD, Raman and UV–Vis spectroscopies. Solid foams were stabilized by NP complexes with cationic surfactants. The foam morphology was characterized and photocatalytic activity was demonstrated in water. The present work paves the way for the development of efficient systems for air and water purification in demanding technological sectors, such as aerospace
Exhaled nitric oxide in patients with PiZZ Phenotype-related α 1-anti-trypsin deficiency
AbstractThere is no report of exhaled NO (eNO) in subjects with different phenotypes ofα1 -anti-trypsin (AAT) deficiency.Exhaled nitric oxide was evaluated by means of single-breath chemiluminescence analysis (fractional exhaled concentration at the plateau level [plFENO]) in 40 patients with AAT deficiency. Patients were divided according to the protease inhibitor (Pi) phenotype: PiMZ/MS, n=25; PiSZ n=6; PiZZ, n=9. Nineteen healthy subjects served as controls. Levels of eNO in PiZZ patients were also compared with those of subjects, without AAT deficiency (PiMM), matched for diagnosis, sex, age, smoking habit and forced expiratory volume in 1 sec (FEV1). In AAT deficiency subjects airway hyper-responsiveness to methacholine (PD20FEV1) was also assessed.plFENOwas significantly lower in the PiZZ group (4·5±1·4 ppb) than in matched PiMM subjects (8·2±3·8 ppb), in healthy controls (9·3±2·8 ppb) and in patients of other phenotypes. Dynamic lung volumes and DLCOwere significantly lower in PiZZ than in other AAT-deficient patients. Bronchial hyper-responsiveness was not different among AAT phenotypes.These results suggest that eNO may be significantly reduced in PiZZ as compared to healthy control subjects and to AAT subjects with other phenotypes, independent of the level of airway obstruction. Whether, at least potentially, eNO may be considered as an early marker of lung involvement in AAT deficiency must be confirmed with studies on larger number of subjects
Modular symbols in Iwasawa theory
This survey paper is focused on a connection between the geometry of
and the arithmetic of over global fields,
for integers . For over , there is an explicit
conjecture of the third author relating the geometry of modular curves and the
arithmetic of cyclotomic fields, and it is proven in many instances by the work
of the first two authors. The paper is divided into three parts: in the first,
we explain the conjecture of the third author and the main result of the first
two authors on it. In the second, we explain an analogous conjecture and result
for over . In the third, we pose questions for general
over the rationals, imaginary quadratic fields, and global function fields.Comment: 43 page
The Wicked Machinery of Government: Malta and the Problems of Continuity under the New Model Administration
This is a study focused on the early years of British rule in Malta (1800-1813). It explores the application to the island of the “new model” of colonial government, one based on direct rule from London mediated by the continuation of existing laws and institutions. Systemic deficiencies are identified. These tended to undermine the effectiveness of direct British rule. This study also reveals, in the context of legal and constitutional continuity, unresolved tensions between modernity and tradition. The political stability of the island was damaged and the possibility of continued British possession was threatened
Ballata
Ġabra ta’ poeżiji u proża li tinkludi: Lil Dun Anton Mifsud ta’ Dun Karm – Hekk Kien Miktub ta’ A. Cremona – Mara tad-Dnub ta’ Arthur V. Vassallo – Għajn Riħana ta’ George Zammit – Il-Mewt ta’ Ġużè Chetcuti – Ballata ta’ Ros. Briffa.N/
Deuterium retention and erosion in liquid Sn samples exposed to D2 and Ar plasmas in GyM device
The use of tin (Sn) as a liquid metal for plasma facing components has been recently proposed as a solution to the high heat load issue on the divertor target plates in nuclear fusion reactors. Due to its low vapor pressure, low reactivity with hydrogen and good resilience to neutron impact, tin is a good candidate as plasma facing component. However its high atomic number poses concerns about plasma contamination.In this paper two fundamental aspects have been investigated: deuterium retention and erosion fluxes from the Sn surface towards the plasma. The samples were exposed to plasma inside the linear machine GyM in magnetic cusp configuration. This setup permits to expose free liquid specimens without the need for the Capillary Porous System. Moreover it permits to lower the magnetic field in order to increase Sn Larmor radius and consequently limit Sn re-deposition in erosion experiments.Ex-situ analyses by ion beam diagnostics on solid samples exposed to deuterium plasma have proved that the amount of retained atomic deuterium is very low, approximately 0.18 at% estimated by Nuclear Reaction Analysis and 0.25 at% estimated by Elastic Recoil Detection Analysis.In the framework of erosion studies, the spectroscopic parameter S/XB was evaluated in Ar plasma for the SnI line at 380.1 nm by Optical Emission Spectroscopy and mass loss measurements in the 5–11 eV Te range, at a density ne ∼ 1.5 × 1011 cm−3. An average value of 150 ± 23 was obtained. Keywords: Liquid metals, Deuterium retention, Erosion, Double-cusp magnetic configuration, Ion beam diagnostics, S/XB spectroscopic paramete
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