This study presents a particular mechanical device for lower limb amputees, a prosthetic ankle, designed for swimming and partially for walking in two possible configurations. Experimental static ...tests are carried out for a compliance according to the standard, in the configuration for walking which is considered the most severe in terms of loading. In parallel, a numerical model is created and validated by a comparison to the experimental test in terms of displacements and strains. The validated FE model is then used for an optimization of the geometry and of the used materials, and to provide a further simulation for the configuration of swimming.
Studying the evolution of galaxies located within groups may have important implications for the authors' understanding of the global evolution of the galaxy population as a whole. Using the group ...catalog obtained from zCOSMOS spectroscopic data and the complementary photometric data from the COSMOS survey, they explore segregation effects occurring in groups of galaxies at intermediate/high redshifts. Their aim is to reveal if, and how significantly, group environment affects the evolution of infalling galaxies. They built two composite groups at intermediate and high redshifts, and they divided the corresponding composite group galaxies into three samples according to their distance from the group center. They found that the most massive galaxies in their sample do not display any strong group-centric dependence of the fractions of red/blue objects. For galaxies of lower masses, there is a radial dependence in the changing mix of red and blue galaxies. This dependence is most evident in poor groups, whereas richer groups do not display any obvious trend of the blue fraction.
Aims. We present a continuation of our study about the relation between stellar mass and gas-phase metallicity in the VIMOS VLT Deep Survey (VVDS). In this work we extend the determination of ...metallicities up to redshift ≈1.24 for a sample of 42 star-forming galaxies with a mean redshift value of 0.99. Methods: For a selected sample of emission-line galaxies, we use both diagnostic diagrams and empirical calibrations based on Oii emission lines along with the empirical relation between the intensities of the Oiii and Neiii emission lines and the theoretical ratios between Balmer recombination emission lines to identify star-forming galaxies and to derive their metallicities. We derive stellar masses by fitting the whole spectral energy distribution with a set of stellar population synthesis models. Results: These new methods allow us to extend the mass-metallicity relation to higher redshift. We show that the metallicity determinations are consistent with more established strong-line methods. Taken together this allows us to study the evolution of the mass-metallicity relation up to z ≈ 1.24 with good control of systematic uncertainties. We find an evolution with redshift of the average metallicity of galaxies very similar to those reported in the literature: for a given stellar mass, galaxies at z ~ 1 have, on average, a metallicity ~ 0.3 dex lower than galaxies in the local universe. However we do not see any significant metallicity evolution between redshifts z ~ 0.7 (Paper I) and z ~ 1.0 (this paper). We find also the same flattening of the mass-metallicity relation for the most massive galaxies as reported in Paper I at lower redshifts, but again no apparent evolution of the slope is seen between z ~ 0.7 and z ~ 1.0. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, program 070.A-9007, and on data obtained at the Canada-France-Hawaii Telescope, operated by the CNRS in France, CNRC in Canada and the University of Hawaii.
MISTRAL is the new Faint Object Spectroscopic Camera mounted at the folded Cassegrain focus of the 1.93m telescope of Haute-Provence Observatory. We describe the design and components of the ...instrument and give some details about its operation. We emphasise in particular the various observing modes and the performances of the detector. A short description is also given about the working environment. Various types of objects, including stars, nebulae, comets, novae, galaxies have been observed during various test phases to evaluate the performances of the instrument. The instrument covers the range of 4000 to 8000A with the blue setting, or from 6000 to 10000A with the red setting, at an average spectral resolution of 700. Its peak efficiency is about 22% at 6000A. In spectroscopy, a limiting magnitude of 19.5 can be achieved for a point source in one hour with a signal to noise of 3 in the continuum (and better if emission lines are present). In imaging mode, limiting magnitudes of 20-21 can be obtained in 10-20mn (with average seing conditions of 2.5 arcsec at OHP). The instrument is very users-friendly and can be put into operations in less than 15mn (rapid change-over from the other instrument in use) if required by the science (like for Gamma-Rays Bursts). Some first scientific results are described for various types of objects, and in particular for the follow-up of GRBs. While some further improvements are still under way, in particular to ease the switch from blue to red setting and add more grisms or filters, MISTRAL is ready for the follow-up of transients and other variable objects, in the soon-to-come era of e.g. the SVOM satellite and of the Rubin telescope.
Context: The rate at which galaxies grow via successive mergers is a key element in understanding the main phases of galaxy evolution. Aims: We measure the evolution of the fraction of galaxies in ...pairs and the merging rate since redshift z 1 assuming a (H0 = 70 km s-1 Mpc-1, ΩM = 0.3 and ΩΛ = 0.7) cosmology. Methods: From the VIMOS VLT Deep Survey we use a sample of 6464 galaxies with I_AB ≤ 24 to identify 314 pairs of galaxies, each member with a secure spectroscopic redshift, which are close in both projected separation and in velocity. Results: We estimate that at z 0.9, 10.9 ± 3.2% of galaxies with MB(z) ≤ -18-Qz (Q = 1.11) are in pairs with separations Δ rp ≤ 20 h-1 kpc, Δ v≤ 500 km s-1, and with Δ MB ≤ 1.5, significantly larger than 3.8 ± 1.7% at z 0.5; thus, the pair fraction evolves as (1 + z)m with m = 4.73 ± 2.01. For bright galaxies with MB(z = 0) ≤ -18.77, the pair fraction is higher and its evolution with redshift is flatter with m = 1.50 ± 0.76, a property also observed for galaxies with increasing stellar masses. Early-type pairs (dry mergers) increase their relative fraction from 3% at z 0.9 to 12% at z 0.5. The star formation rate traced by the rest-frame OII EW increases by 26 ± 4% for pairs with the smallest separation rp ≤ 20 h-1 kpc. Following published prescriptions to derive merger timescales, we find that the merger rate of MB(z) ≤ -18-Qz galaxies evolves as N_mg = (4.96 ± 2.07)×10-4×(1 + z)2.20 ± 0.77 mergers Mpc-3 Gyr-1. Conclusions: The merger rate of galaxies with MB(z) ≤ -18-Qz has significantly evolved since z 1 and is strongly dependent on the luminosity or stellar mass of galaxies. The major merger rate increases more rapidly with redshift for galaxies with fainter luminosities or stellar mass, while the evolution of the merger rate for bright or massive galaxies is slower, indicating that the slow evolution reported for the brightest galaxies is not universal. The merger rate is also strongly dependent on the spectral type of galaxies involved. Late-type mergers were more frequent in the past, while early-type mergers are more frequent today, contributing to the rise in the local density of early-type galaxies. About 20% of the stellar mass in present day galaxies with log(M/M{ȯ}) ≥ 9.5 has been accreted through major merging events since z = 1. This indicates that major mergers have contributed significantly to the growth in stellar mass density of bright galaxies over the last half of the life of the Universe. based on observations obtained with the European Southern Observatory Telescopes at the Paranal Observatory, under programs 072.A-0586 and 073.A-0647.
Object of the present study is an ankle prosthesis for transtibial amputees, designed for children. Standards for prostheses compliance available in literature are all related to adults, while very ...few studies are present for children. In the first part of the paper a discussion on the modification of the standard in terms of loads and distances is presented, to adapt the available data to the test case, a boy of 12 years and 45 kg. In the second part, experimental results are shown, considering four different types of tests: static proof and ultimate tests, fatigue tests and static torsion tests. Results were positive for the designed and tested ankle prosthesis.
The headache is a very frequent symptom and represents the 0.36%-2.5% of all reasons of claim to Emergency Department. Even if it is rarely related to high risk diseases, it is mandatory to promptly ...differentiate life-threatening conditions. In order to establish a correct diagnostic and therapeutic pathway and ask for aimed specialistic consultation, the emergency physician must be familiar with the various categories of headache. It is important to distinguish between essential headache and secondary headache. All patients presenting to the emergency department with the complaint of headache should be interviewed carefully regarding their history. The quality of pain associated with the intensity, location, rate, duration, modality of onset, relieving or worsening conditions, response to drugs, symptoms or signs associated must be investigated as well. Careful neurological examination including the vision of fundus oculi and the evaluation of rigor nucalis can provide further important diagnostic information. Laboratory exams do not usually give significant issues in the majority of patients with headache. However, dosage of inflammation index can be useful when an infective or inflammatory disease is suspected. CT scan can rule-out the suspicion of organic intracranial causes. When the physician suspects meningitis or subarachnoid hemorrhage (SAH) not showed by CT scanning, rachicentesis can turn out diagnostic. The modality of onset, clinical characteristics and differential diagnosis of subarachnoid hemorrhage, intracranial hypertension, colloidal cyst of the third ventricle, trigeminal neuralgia, temporal arteritis and pituitary adenomas and apoplexy will be discussed. These diseases are not only of neurological and neurosurgical interest, but involve also the physician in the Emergency Department.
Melanocytic nevi, both congenital and acquired, are considered to be precursors of melanomas. Data about the malignant potential of these nevi are conflicting, particularly with reference to the ...nevus of the smallest size. Patients with preexisting melanocytic nevi (both congenital and acquired) have risks of developing melanoma that differ from those of subjects without them. The purpose of this study was to verify the presence of melanoma in preexisting nevi both congenital (congenital nevus associated melanoma) (CNAM) and acquired (ANAM). In particular, we investigated melanomas associated with small congenital nevi (SCN). A cohort of 190 patients with primary melanomas was studied. Congenital nevi were called “small” (SCN) when their diameters were less than 1.5 cm. Epiluminescence microscopy (ELM) was performed to further improve the clinical diagnosis and to observe the more subtle changes in the preexisting nevi. Forty of the 190 cases of melanoma were associated with preexisting nevi; of these, 15 had congenital features with a CNAM largest diameter of 1.5 cm. These 15 cases were melanomas of the superficial type with a mean tumor thickness lower than that of ANAM (0.33 vs 1.50). There were no differences between the locations of CNAM and other melanomas. Male patients were significantly more affected. ELM microscopy permitted us to detect the early malignant changes in nevi and thus to improve our diagnosis. A high percentage of small congenital nevi were found to be associated with melanomas. They may be considered as melanomas precursors. Because of their large number and frequency, prophylactic removal of all SCN is not feasible. However, they should be removed as soon as possible when clinical or ELM changes are observed.
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