1,244 research outputs found
Band gaps in the relaxed linear micromorphic continuum
In this note we show that the relaxed linear micromorphic model recently
proposed by the authors can be suitably used to describe the presence of
band-gaps in metamaterials with microstructures in which strong contrasts of
the mechanical properties are present (e.g. phononic crystals and lattice
structures). This relaxed micromorphic model only has 6 constitutive parameters
instead of 18 parameters needed in Mindlin- and Eringen-type classical
micromorphic models. We show that the onset of band-gaps is related to a unique
constitutive parameter, the Cosserat couple modulus which starts to
account for band-gaps when reaching a suitable threshold value. The limited
number of parameters of our model, as well as the specific effect of some of
them on wave propagation can be seen as an important step towards indirect
measurement campaigns
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Geographic variability in the grey mullet Mugil cephalus: preliminary results of mtDNA and chromosome analyses
The grey mullet, Mugil cephalus, plays an important role in the fisheries and aquaculture of tropical and subtropical regions of the world. This species is considered cosmopolitan, but its distribution appears peculiar with regard to the coastal ecology of the species. A multidisciplinary study of the geographic variability of this species, through a cytogenetic, molecular and morphometric characterization, was undertaken to detect whether genetically distinct populations occur. The preliminary results from analyses of mitochondrial DNA and of chromosomes of seven different populations around the world are reported. The different populations analysed are well discriminated by mtDNA analyses: samples are clustered in four groups, Mediterranean, East Atlantic, Central Pacific and East Pacific, with a maximum sequence divergence of 3.3%. The karyotype of all the populations studied is uniformly composed of 48 acrocentric chromosomes, and neither heterochromatin distribution nor nucleolus organizer regions allow the identification of chromosomal markers useful in distinguishing these genetically differentiated groups of populations. © 1993
Prevalence of psychiatric disorders in thyroid diseased patients.
Several studies have underlined the high prevalence of psychiatric symptoms and disorders in thyroid diseases. The aim of this study was to evaluate the prevalence of psychiatric disorders in 93 inpatients affected by different thyroid diseases during their lifetimes, by means of a standardized instrument, i.e., the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-III-Revised, Upjohn Version (SCID-UP-R). The results showed higher rates of panic disorder, simple phobia, obsessive-compulsive disorder, major depressive disorder, bipolar disorder and cyclothymia in thyroid patients than in the general population. These findings would suggest that the co-occurrence of psychiatric and thyroid diseases may be the result of common biochemical abnormalities
Calibration of centre-of-mass energies at LEP 2 for a precise measurement of the W boson mass
The determination of the centre-of-mass energies for all LEP 2 running is
presented. Accurate knowledge of these energies is of primary importance to set
the absolute energy scale for the measurement of the W boson mass. The beam
energy between 80 and 104 GeV is derived from continuous measurements of the
magnetic bending field by 16 NMR probes situated in a number of the LEP
dipoles. The relationship between the fields measured by the probes and the
beam energy is defined in the NMR model, which is calibrated against precise
measurements of the average beam energy between 41 and 61 GeV made using the
resonant depolarisation technique. The validity of the NMR model is verified by
three independent methods: the flux-loop, which is sensitive to the bending
field of all the dipoles of LEP; the spectrometer, which determines the energy
through measurements of the deflection of the beam in a magnet of known
integrated field; and an analysis of the variation of the synchrotron tune with
the total RF voltage. To obtain the centre-of-mass energies, corrections are
then applied to account for sources of bending field external to the dipoles,
and variations in the local beam energy at each interaction point. The relative
error on the centre-of-mass energy determination for the majority of LEP 2
running is 1.2 x 10^{-4}, which is sufficiently precise so as not to introduce
a dominant uncertainty on the W mass measurement.Comment: 79 pages, 45 figures, submitted to EPJ
Salivary Metabolomic Signatures and Body Mass Index in Italian Adolescents: A Pilot Study
Context: Obesity surveillance is scarce in adolescents, and little is known on whether salivary metabolomics data, emerging minimally invasive biomarkers, can characterize metabolic patterns associated with overweight or obesity in adolescents. Objective: This pilot study aims to identify the salivary molecular signatures associated with body mass index (BMI) in Italian adolescents. Methods: Saliva samples and BMI were collected in a subset of n = 74 young adolescents enrolled in the Public Health Impact of Metal Exposure study (2007-2014). A total of 217 untargeted metabolites were identified using liquid chromatography-high resolution mass spectrometry. Robust linear regression was used to cross-sectionally determine associations between metabolomic signatures and sex-specific BMI-for-age z-scores (z-BMI). Results: Nearly 35% of the adolescents (median age: 12 years; 51% females) were either obese or overweight. A higher z-BMI was observed in males compared to females (P = .02). One nucleoside (deoxyadenosine) and 2 lipids (18:0-18:2 phosphatidylcholine and dipalmitoyl-phosphoethanolamine) were negatively related to z-BMI (P < .05), whereas 2 benzenoids (3-hydroxyanthranilic acid and a phthalate metabolite) were positively associated with z-BMI (P < .05). In males, several metabolites including deoxyadenosine, as well as deoxycarnitine, hyodeoxycholic acid, N-methylglutamic acid, bisphenol P, and trigonelline were downregulated, while 3 metabolites (3-hydroxyanthranilic acid, theobromine/theophylline/paraxanthine, and alanine) were upregulated in relation to z-BMI (P < .05). In females, deoxyadenosine and dipalmitoyl-phosphoethanolamine were negatively associated with z-BMI while deoxycarnitine and a phthalate metabolite were positively associated (P < .05). A single energy-related pathway was enriched in the identified associations in females (carnitine synthesis, P = .04). Conclusion: Salivary metabolites involved in nucleotide, lipid, and energy metabolism were primarily altered in relation to BMI in adolescents
An Industry-Relevant Metal Mixture, Iron Status, and Reported Attention-Related Behaviors in Italian Adolescents
BACKGROUND: Exposure to environmental metals has been consistently associated with attention and behavioral deficits in children, and these associations may be modified by coexposure to other metals or iron (Fe) status. However, few studies have investigated Fe status as a modifier of a metal mixture, particularly with respect to attention -related behaviors. METHODS: We used cross-sectional data from the Public Health Impact of Metals Exposure study, which included 707 adolescents (10-14 years of age) from Brescia, Italy. Manganese, chromium, and copper were quantified in hair samples, and lead was quantified in whole blood, using inductively coupled plasma mass spectrometry. Concentrations of Fe status markers (ferritin, hemoglobin, transferrin) were measured using immunoassays or luminescence assays. Attention -related behaviors were assessed using the Conners Rating Scales Self -Report Scale-Long Form, Parent Rating Scales Revised-Short Form, and Teacher Rating Scales Revised-Short Form. We employed Bayesian kernel machine regression to examine associations of the metal mixture with these outcomes and evaluate Fe status as a modifier. RESULTS: Higher concentrations of the metals and ferritin were jointly associated with worse self -reported attention -related behaviors: metals and ferritin set to their 90th percentiles were associated with 3.0% [0 = 0.03; 95% credible interval (CrI): -0.01, 0.06], 4.1% (0 = 0.04; 95% CrI: 0.00, 0.08), and 4.1% (0= 0.04; 95% CrI: 0.00, 0.08) higher T -scores for self -reported attention deficit/hyperactivity disorder (ADHD) index, inattention, and hyperactivity, respectively, compared with when metals and ferritin were set to their 50th percentiles. These associations were driven by hair manganese, which exhibited nonlinear associations with all self -reported scales. There was no evidence that Fe status modified the neurotoxicity of the metal mixture. The metal mixture was not materially associated with any parent -reported or teacher -reported scale. CONCLUSIONS: The overall metal mixture, driven by manganese, was adversely associated with self -reported attention -related behavior. These findings suggest that exposure to multiple environmental metals impacts adolescent neurodevelopment, which has significant public health implications. https://doi.org/10.1289/EHP1298
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