413 research outputs found
Electron-correlation effects in the -factor of light Li-like ions
We investigate electron-correlation effects in the -factor of the ground
state of Li-like ions. Our calculations are performed within the
nonrelativistic quantum electrodynamics (NRQED) expansion up to two leading
orders in the fine-structure constant , and . The
dependence of the NRQED results on the nuclear charge number is studied and
the individual -expansion contributions are identified. Combining the
obtained data with the results of the all-order (in ) calculations
performed within the expansion, we derive the unified theoretical
predictions for the -factor of light Li-like ions.Comment: 9 pages, 4 table
Field relations and petrology of the Trafalgar Plutonic Suite and comparisons with other Devonian granitoid plutons in the Meguma terrane, Nova Scotia, Canada
The Trafalgar Plutonic Suite intruded metasedimentary rocks of the Goldenville and Halifax groups in the northeastern part of the Meguma terrane of southern Nova Scotia at about 374 Ma, based on previously published UâPb and 40Ar/39Ar mineral ages. Using field and petrographic observations, the suite is divided into 20 different plutons on the combined basis of variations in grain size (fine, medium, or coarse), texture (equigranular or porphyritic) and modal mineralogy (quartz diorite/tonalite, granodiorite, monzogranite, and syenogranite). The granodiorite, monzogranite, and syenogranite plutons are relatively uniform in composition with little variation in mineralogy or chemistry within each pluton or between plutons of the same lithology. In contrast the quartz diorite/tonalite plutons show mineralogical and chemical variation, both within and between plutons. The granodiorite, monzogranite, and syenogranite plutons closely resemble other peraluminous granitoid plutons characteristic of the Meguma terrane. The quartz diorite/tonalite plutons are varied but chemically resemble minor Devonian mafic intrusions elsewhere in the Meguma terrane. Like other plutons of the Meguma terrane, the Trafalgar Plutonic Suite has chemical characteristics of volcanic-arc to syn-collisional granitoid rocks and likely has experienced extensive contamination by metasedimentary material as documented by previous studies of plutons in the Meguma terrane. The minor quartz diorite/tonalite plutons are additional examples of the mafic rocks that have been proposed in tectonic models of the Meguma terrane to have facilitated melting of the lower crust to generate granodioritic parent magmas, followed by crystal fractionation and extensive contamination by metasedimentary material.La suite plutonique de Trafalgar sâest mise en place dans les roches mĂ©tasĂ©dimentaires des groupes de Goldenville et Halifax dans la partie nord-est de la zone de Meguma au sud de la Nouvelle-Ăcosse Ă environ 374 Ma, dâaprĂšs des Ăąges U-Pb et 40Ar/39Ar dĂ©jĂ publiĂ©s. Ă partir dâobservations sur le terrain et pĂ©trographiques, la suite se divise en 20 plutons, basĂ© sur un ensemble de caractĂ©ristiques telles que la variation granulomĂ©trique (fin, moyen ou grossier), la texture des roches (Ă©quidimensionnel ou porphyritique) et la proportion minĂ©ralogique (diorite quartzifĂšre/tonalite, granodiorite, monzogranite et syĂ©nogranite). La composition des plutons constituĂ©s de granodiorite, de monzogranite et de syĂ©nogranite est relativement uniforme avec peu de variation minĂ©ralogique ou chimique au sein de chacun des plutons ou dâun pluton Ă un autre de lithologie semblable. En revanche, les plutons formĂ©s de diorite quartzifĂšre/tonalite prĂ©sentent des variations minĂ©ralogiques et chimiques Ă lâintĂ©rieur du mĂȘme pluton et Ă travers la suite plutonique. Les plutons constituĂ©s de granodiorite, de monzogranite et de syĂ©nogranite ressemblent Ă©troitement aux autres granitoĂŻdes peralumineux de la zone de Meguma. Les plutons de diorite quartzifĂšre/tonalite sont variables mais chimiquement comparables aux intrusions mafiques dĂ©voniens retrouvĂ©s ailleurs dans la zone de Meguma. Comme plusieurs autres plutons de la zone de Meguma, la suite plutonique de Trafalgar possĂšde des caractĂ©ristiques chimiques semblables aux granitoĂŻdes de type arc volcanique Ă syncollisionnel et ayant sans doute subi une contamination significative des roches mĂ©tasĂ©dimentaires, tels que documentĂ© dans des Ă©tudes prĂ©cĂ©dentes sur les plutons de la zone de Meguma. Les moins vastes plutons formĂ©s de diorite quartzifĂšre/tonalite constituent des exemples supplĂ©mentaires de roches mafiques qui furent prĂ©sentĂ©es dans des modĂšles tectoniques de la zone de Meguma comme ayant contribuĂ©es Ă la fusion de la croute infĂ©rieure et ainsi gĂ©nĂ©rer un magma parent granodioritique, suivi dâune cristallisation fractionnĂ©e combinĂ©e Ă une contamination importante provenant des roches mĂ©tasĂ©dimentaires
Development of a Pain Management Protocol for a Paediatric Ward in the Gambia, West Africa
Despite recent advances in our understanding of paediatric pain and its management, pain continues to be undertreated globally, particularly in children and in low income countries. This article describes the development of a paediatric analgesia and sedation protocol, tailored to the specific setting of the Medical Research Council (MRC) paediatric ward in the Gambia, West Africa. An iterative process was used throughout development, with inputs from the medical literature, local providers, and pain experts, incorporated to ensure a safe, effective, and locally appropriate protocol. We demonstrate that evidence-based published guidelines, can and should be adapted to allow for optimal pain management given the resources and capabilities of specific health care settings. It is hoped that the process and protocol described here, will not only help to improve care on the MRC ward, but serve as an example to others working toward improving pain management in similar health care settings
Self-energy screening effects in the factor of Li-like ions
We report an investigation of the self-energy screening effects for the
factor of the ground state of Li-like ions. The leading screening contribution
of the relative order is calculated to all orders in the binding nuclear
strength parameter (where is the nuclear charge number and
is the fine-structure constant). We also extend the known results for
the expansion of the QED screening correction by deriving the leading
logarithmic contribution of order and obtaining approximate
results for the and contributions. The comparison of the
two approaches yields a stringent check of consistency of the two calculations
and allows us to obtain improved estimations of the higher-order screening
effects.Comment: Several misprints are corrected in ver.3; Sec. VI is updated in ver.
Transit Timing Analysis in the HAT-P-32 system
We present the results of 45 transit observations obtained for the transiting
exoplanet HAT-P-32b. The transits have been observed using several telescopes
mainly throughout the YETI network. In 25 cases, complete transit light curves
with a timing precision better than min have been obtained. These light
curves have been used to refine the system properties, namely inclination ,
planet-to-star radius ratio , and the ratio between
the semimajor axis and the stellar radius . First analyses by
Hartman et al. (2011) suggest the existence of a second planet in the system,
thus we tried to find an additional body using the transit timing variation
(TTV) technique. Taking also literature data points into account, we can
explain all mid-transit times by refining the linear ephemeris by 21ms. Thus we
can exclude TTV amplitudes of more than min.Comment: MNRAS accepted; 13 pages, 10 figure
Transit Timing Analysis in the HAT-P-32 System
We present the results of 45 transit observations obtained for the transiting exoplanet HATP- 32b. The transits have been observed using several telescopes mainly throughout the YETI (Young Exoplanet Transit Initiative) network. In 25 cases, complete transit light curves with a timing precision better than 1.4 min have been obtained. These light curves have been used to refine the system properties, namely inclination i, planet-to-star radius ratio Rp/Rs, and the ratio between the semimajor axis and the stellar radius a/Rs. First analyses by Hartman et al. suggests the existence of a second planet in the system, thus we tried to find an additional body using the transit timing variation (TTV) technique. Taking also the literature data points into account, we can explain all mid-transit times by refining the linear ephemeris by 21 ms. Thus, we can exclude TTV amplitudes of more than âŒ1.5min
Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii Determination
Changes in the mean-square nuclear charge radii along the lithium isotopic
chain were determined using a combination of precise isotope shift measurements
and theoretical atomic structure calculations. Nuclear charge radii of light
elements are of high interest due to the appearance of the nuclear halo
phenomenon in this region of the nuclear chart. During the past years we have
developed a new laser spectroscopic approach to determine the charge radii of
lithium isotopes which combines high sensitivity, speed, and accuracy to
measure the extremely small field shift of an 8 ms lifetime isotope with
production rates on the order of only 10,000 atoms/s. The method was applied to
all bound isotopes of lithium including the two-neutron halo isotope Li-11 at
the on-line isotope separators at GSI, Darmstadt, Germany and at TRIUMF,
Vancouver, Canada. We describe the laser spectroscopic method in detail,
present updated and improved values from theory and experiment, and discuss the
results.Comment: 34 pages, 24 figures, 14 table
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