3,341 research outputs found
Comparative study on breaking wave forces on vertical walls with cantilever surfaces
Physical experiments (at a scale of 1/20) are carried out using two different models: a vertical wall with cantilevering slab and a simple vertical wall. Tests are conducted for a range of values of water depth, wave period and wave height. The largest peak pressures were recorded at the SWL (82 pghs) on the vertical part and at the fixed corner of the cantilever slab (90 pghs). Pressure measurements and derived force calculations on the simple vertical wall were used to evaluate the existing prediction formulas. A significant effect of the cantilevering part is observed on the total horizontal force and overturning moment of a simple vertical wall. This is due to secondary impact occurring on the overhanging part by a jet climbing on the vertical part
Mariene beschermde gebieden in het Belgisch deel van de Noordzee: een eerste stap in de richting van het behoud van de mariene biodiversiteit?
Molecular epidemiology of penicillin-nonsusceptible Streptococcus pneumoniae among children in Greece
A total of 145 penicillin-nonsusceptible Streptococcus pneumoniae strains
were isolated from young carriers in Greece and analyzed by antibiotic
susceptibility testing, serotyping, restriction fragment end labeling
(RFEL), and penicillin-binding protein (PBP) genotyping. The serotypes 23A
and 23F (54%), 19A and 19F (25%), 9V (5%), 15A, 15B, and 15C (4%), 6A and
6B (4%), and 21 (4%) were most prevalent in this collection. Fifty-three
distinct RFEL types were identified. Sixteen different RFEL clusters,
harboring 2 to 32 strains each, accounted for 82% of all strains. Eight of
these genetic clusters representing 60% of the strains were previously
identified in other countries. A predominant lineage of 66 strains (46%)
harboring five RFEL types and the serotypes 19F and 23F was closely
related to the pandemic clone Spain(23F)-1 (genetic relatedness of > or
=85%). Another lineage, representing 11 strains, showed close genetic
relatedness to the pandemic clone France(9V)-3. Another lineage of 8
serotype 21 strains was Greece specific since the RFEL types were not
observed in an international collection of 193 genotypes from 16 different
countries. Characterization of the PBP genes pbp1a, pbp2b, and pbp2x
revealed 20 distinct PBP genotypes of which PBP type 1-1-1, initially
observed in the pandemic clones 23F and 9V, was predominantly present in
11 RFEL types in this Greek collection of penicillin-nonsusceptible
strains (55%). Sixteen PBP types covering 52 strains (36%) were Greece
specific. This study underlines the strong contribution of
penicillin-resistant international clones to the prevalence and spread of
penicillin-nonsusceptible pneumococci among young children in Greece
Low energy measurement of the 7Be(p,gamma)8B cross section
We have measured the cross section of the 7Be(p,gamma)8B reaction for E_cm =
185.8 keV, 134.7 keV and 111.7 keV using a radioactive 7Be target (132 mCi).
Single and coincidence spectra of beta^+ and alpha particles from 8B and 8Be^*
decay, respectively, were measured using a large acceptance spectrometer. The
zero energy S factor inferred from these data is 18.5 +/- 2.4 eV b and a
weighted mean value of 18.8 +/- 1.7 eV b (theoretical uncertainty included) is
deduced when combining this value with our previous results at higher energies.Comment: Accepted for publication in Phys. Rev. Let
Means and covariance functions for geostatistical compositional data: an axiomatic approach
This work focuses on the characterization of the central tendency of a sample
of compositional data. It provides new results about theoretical properties of
means and covariance functions for compositional data, with an axiomatic
perspective. Original results that shed new light on the geostatistical
modeling of compositional data are presented. As a first result, it is shown
that the weighted arithmetic mean is the only central tendency characteristic
satisfying a small set of axioms, namely continuity, reflexivity and marginal
stability. Moreover, this set of axioms also implies that the weights must be
identical for all parts of the composition. This result has deep consequences
on the spatial multivariate covariance modeling of compositional data. In a
geostatistical setting, it is shown as a second result that the proportional
model of covariance functions (i.e., the product of a covariance matrix and a
single correlation function) is the only model that provides identical kriging
weights for all components of the compositional data. As a consequence of these
two results, the proportional model of covariance function is the only
covariance model compatible with reflexivity and marginal stability
Early-onset primary antibody deficiency resembling common variable immunodeficiency challenges the diagnosis of Wiedeman-Steiner and Roifman syndromes
Syndromic primary immunodeficiencies are rare genetic disorders that affect both the immune system and other organ systems. More often, the immune defect is not the major clinical problem and is sometimes only recognized after a diagnosis has been made based on extra-immunological abnormalities. Here, we report two sibling pairs with syndromic primary immunodeficiencies that exceptionally presented with a phenotype resembling early-onset common variable immunodeficiency, while extra-immunological characteristics were not apparent at that time. Additional features not typically associated with common variable immunodeficiency were diagnosed only later, including skeletal and organ anomalies and mild facial dysmorphism. Whole exome sequencing revealed KMT2-Aassociated Wiedemann-Steiner syndrome in one sibling pair and their mother. In the other sibling pair, targeted testing of the known disease gene for Roifman syndrome (RNU4ATAC) provided a definite diagnosis. With this study, we underline the importance of an early-stage and thorough genetic assessment in paediatric patients with a common variable immunodeficiency phenotype, to establish a conclusive diagnosis and guide patient management. In addition, this study extends the mutational and immunophenotypical spectrum of Wiedemann-Steiner and Roifman syndromes and highlights potential directions for future pathophysiological research
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