Intrinsic quadrupole moment of the nucleon

We address the question of the intrinsic quadrupole moment Q_0 of the nucleon in various models. All models give a positive intrinsic quadrupole moment for the proton. This corresponds to a prolate deformation. We also calculate the intrinsic quadrupole moment of the Delta(1232). All our models lead to a negative intrinsic quadrupole moment of the Delta corresponding to an oblate deformation.Comment: 17 pages, 5 figure

Carbon isotope dynamics in Abies amabilis stands in the Cascades

Journal ArticleCarbon isotope ratios (d13C) of canopy air and carbon isotope discrimination at the ecosystem level were studied in three montane Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes) stands, an old-growth and two younger stands. Spatial and temporal variations of canopy CO2 concentrations ([CO2]) and their d13C were strongly related to stand structure. Within the old-growth stand, both daytime canopy [CO2] and canopy d13C stayed close to those of the troposphere, either indicating low overall photosynthetic rates or high turbulent mixing

Particle image velocimetry measurements of blood flow in a modeled carotid artery bifurcation

Cardiovascular diseases are on of the leading causes of mortality and morbidity in the western world. Amongst these diseases, atherosclerosis, a progressive narrowing of the arterial wall is one of the most severe and if untreated may lead to stroke or ischemic infarction. Fluid mechanic forces are a key player in the early development and progression of atherosclerosis and a better understanding of the interplay between haemodynamic and vascular diseases is needed. The carotid artery (CA) in one of the predominant sites of atherosclerotic plaque formation. In this work a transparent, scaled model of an average human carotid artery (AHCA) bifurcation was constructed and steady blood flow at Re = 290 and Re = 700 was simulated using an aqueous glycerin solution. Particle Image Velocimetry (PIV) measurements were performed in the plane of bifurcation and three axial planes in the carotid sinus. Flow inside the CA bifurcation was found to be three-dimensional with strong secondary currents due to the curvature of the vessel. An accurate method for wall shear stress (WSS) calculation along the outer internal carotid artery (ICA) wall is introduced. The method was tested against synthetically generated particle images and was found to perform best for an 8x8 pix2 interrogation windows. A large low momentum flow region with low WSS along the outer ICA wall exists, posing the potential for atherosclerotic plaque formation. Calculated WSS ranged between 0 and 21. Pa and compared well with in-vivo data

Exploring the Added Value of Population Distribution Indicators for Studies of European Urban Form

In Europe, landscape metrics dominate studies that apply quantitative analyses to urban form. Indicators describing population distribution in more detail than just population density, which in Europe are often neglected because of the difficulty in data acquisition, are likely to be more adequate for describing the socioeconomic perspective on urban form. This study aims to disclose the linkage between landscape metrics and population distribution metrics and to provide a better understanding of population distribution patterns. In our study, we quantified urban form in 35 European cities using the most common indicators from both groups of indicators, including measures for the gradient of population density with distance from the city center or (in-) equality of population distribution. We found that landscape metrics correlate only weakly with population distribution indicators by analyzing the correlation matrix. To obtain more insight into the largely neglected group of population distribution indicators, we also applied a regression analysis to understand their underlying information. The results show that population distribution indicators are related to other basic characteristics of cities, such as planning coordination and latitude. The indicated influence of national planning regime on urban form could stimulate further discussion on the effectiveness of urban planning measures. Our study demonstrates that population distribution indicators provide a different perspective than landscape metrics in describing urban form. We therefore stress that it is essential to include population distribution indicators also for describing European cities when aiming to comprehensively describe urban form

Methodological tests of the use of trace elements as tracers to assess root activity

peer-reviewedN.J.H. was funded by the Irish Research Council, co-funded by Marie Curie Actions under FP7. The field experiments A, B and G were supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under the grant agreements FP7-266018 (AnimalChange) and FP7- 244983 (MultiSward). Experiment F was supported by the German Science Foundation (FOR 456).Background and aims There is increasing interest in how resource utilisation in grassland ecosystems is affected by changes in plant diversity and abiotic conditions. Research to date has mainly focussed on aboveground responses and there is limited insight into belowground processes. The aim of this study was to test a number of assumptions for the valid use of the trace elements caesium, lithium, rubidium and strontium as tracers to assess the root activity of several grassland species. Methods We carried out a series of experiments addressing the reliability of soil labelling, injection density, incubation time, application rate and the comparability of different tracers in a multiple tracer method. Results The results indicate that it is possible to achieve a reliable labelling of soil depths. Tracer injection density affected the variability but not the mean level of plant tracer concentrations. Tracer application rates should be based on pilot studies, because of site- and species-specific responses. The trace elements did not meet prerequisites to be used in a multiple tracer method. Conclusions The use of trace elements as tracers is potentially a very useful tool to give insight into plant root activity at different soil depths. This work highlights some of the main benefits and pitfalls of the method and provides specific recommendations to assist the design of tracer experiments and interpretation of the results.N.J.H. was funded by the Irish Research Council, co-funded by Marie Curie Actions under FP7. The field experiments A, B and G were supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under the grant agreements FP7-266018 (AnimalChange) and FP7- 244983 (MultiSward). Experiment F was supported by the German Science Foundation (FOR 456).European Unio

Radiative decays of decuplet hyperons

We calculate the radiative decay widths of decuplet hyperons in a chiral constituent quark model including electromagnetic exchange currents between quarks. Exchange currents contribute significantly to the E2 transition amplitude, while they largely cancel for the M1 transition amplitude. Strangeness suppression of the radiative hyperon decays is found to be weakened by exchange currents. Differences and similarities between our results and other recent model predictions are discussed.Comment: 11 pages, 1 eps figure, revtex, accepted for publication in Phys. Rev.

Intrapartum-related birth asphyxia in South Africa lessons From the first national perinatal care survey

Background. The recent amalgamation of data by users of the Perinatal Problem Identification Programme (PPIP) throughout South Africa has culminated in the publication of the Saving Babies report.Objectives. To determine the absolute rate of death from intrapartum-related birth asphyxia, and the contribution of intrapartum-related asphyxia to total perinatal mortality in South African hospitals, and to identify the primary obstetric causes and avoidable factors for these deaths.Methods. The amalgamated PPIP data for the year 2000 were obtained from 27 state hospitals (6 metropolitan, 12 town and 9 rural) in South Africa. In PPIP-based audit, all perinatal deaths are assigned primary obstetric causes and avoidable factors, and these elements were obtained for all deaths resulting from intrapartum-related birth asphyxia. Results. There were 123 508 births in the hospitals surveyed, with 4 142 perinatal deaths among infants ≥ 1 000 g, giving a perinatal mortality rate of 33.5/1 000 births. The perinatal mortality rate from intrapartum-related birth asphyxia was 4.8/1 000 births. The most frequent avoidable factors were delay by mothers in seeking attention during labour (36.6%), signs of fetal distress interpreted incorrectly (24.9%), inadequate fetal monitoring (18.0%) and no response to poor progress in labour (7.0%). The perinatal mortality rates for metropolitan, town and rural areas were 30.0, 39.4 and 30.9/1 000 births respectively. The contribution of intrapartum-related birth asphyxia to perinatal mortality in these areas was 10.8%, 16.7% and 26.4% respectively

Airflow in a Domestic Kitchen Oven measured by Particle Image Velocimetry

Particle Image Velocimetry (PIV) was used to map the internal airflow of a domestic kitchen oven. Oven cooking performance is dependant on the airflow within the cavity. Previous flow measurement techniques such as hot wire anemometry and pitot probes are very time consuming and prone to error in the hot recirculating flow in an oven. The oven cavity, a commercially available mid-range oven, was modified for optical access. The PIV system consisted of a CCD camera, light sheet illumination from a pulsed Nd:YAG laser, and propanediol droplets and hollow glass spheres with a Stokes number of less than 0.055. Experiments were conducted in an empty oven at room temperature and at 180oC, and at 180oC with a single cooking tray installed. Velocity fields were measured in seven adjacent, coplanar object planes each on four different planes in the oven. The velocity data was averaged to yield mean flow fields, and the seven coplanar data fields were subsequently collaged to produce a full cross-sectional velocity map for each oven plane. In the cold and hot empty cavity a single vortex centred on the fan axis was seen, with strong radial flow. The maximum measured velocity in the cold oven was 1.8ms-1, which compared well with earlier hot-wire measurements. When a tray was introduced, the single vortex was replaced by three circulatory features. Shear flow was seen on both upper and lower sides of the tray, with a lower velocity and a stagnation point on the upper side

The Matter and the Pseudoscalar Densities in Lattice QCD

The matter and the pseudoscalar densities inside a hadron are calculated via gauge-invariant equal-time correlation functions. A comparison is made between the charge charge and the matter density distributions for the pion, the rho, the nucleon and the $\Delta^+$ within the quenched theory, and with two flavours of dynamical quarks.Comment: Typos corrected; 13 pages, 16 figure