2,214 research outputs found

    Aerosol optical properties at Lampedusa (Central Mediterranean) ? 2. Determination of single scattering albedo at two wavelengths for different aerosol types

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    International audienceAerosol optical properties were retrieved from direct and diffuse spectral irradiance measurements made by a multi-filter rotating shadowband radiometer (MFRSR) at the island of Lampedusa (35.5° N, 12.6° E), in the Central Mediterranean, in the period July 2001?September 2003. In a companion paper (Pace et al., 2005) the aerosol optical depth (AOD) and Ångström exponent were used together with airmass backward trajectories to identify and classify different aerosol types. The MFRSR diffuse-to-direct ratio (DDR) at 415.6 nm and 868.7 nm for aerosol classified as biomass burning-urban/industrial, originating primarily from the European continent, and desert dust, originating from the Sahara, is used in this study to estimate the aerosol single scattering albedo (SSA). A detailed radiative transfer model is initialized with the measured aerosol optical depth; calculations are performed at the two wavelengths varying the SSA values until the modelled DDR matches the MFRSR observations. Sensitivity studies are performed to estimate how uncertainties on AOD, DDR, asymmetry factor (g), and surface albedo influence the retrieved SSA values. The results show that a 3% variation of AOD or DDR produce a change of about 0.02 in the retrieved SSA value at 415.6 and 868.7 nm; a ±0.06 variation of the asymmetry factor g produces a change of the estimated SSA of <0.04 at 415.6 nm, and <0.06 at 868.7 nm; finally, an increase of the assumed surface albedo of 0.05 gives very small changes (0.01?0.02) in the retrieved SSA. The calculations show that the SSA of desert dust (DD) increases with wavelength, from 0.81±0.05 at 415.6 nm to 0.94±0.05 at 868.7 nm; on the contrary, the SSA of urban/industrial (UN) aerosols decreases from 0.96±0.02 at 415.6 nm to 0.87±0.07 at 868.7 nm; the SSA of biomass burning (BB) particles is 0.82±0.04 at 415.6 nm and 0.80±0.05 at 868.7 nm. Episodes of UN aerosols occur usually in June and July; BB aerosol episodes with large AOD and long duration are observed mainly in July and August, the driest months of the year, when the development of fires is favoured

    Holocene slip rate variability along the Pernicana fault system (Mt. Etna, Italy): Evidence from offset lava flows

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    The eastern flank of the Mount Etna stratovolcano is affected by extension and is slowly sliding eastward into the Ionian Sea. The Pernicana fault system forms the border of the northern part of this sliding area. It consists of three E-W−oriented fault sectors that are seismically active and characterized by earthquakes up to 4.7 in magnitude (M) capable of producing ground rupture and damage located mainly along the western and central sectors, and by continuous creep on the eastern sector. A new topographic study of the central sector of the Pernicana fault system shows an overall bell-shaped profile, with maximum scarp height of 35 m in the center of the sector, and two local minima that are probably due to the complex morphological relation between fault scarp and lava flows. We determined the ages of lava flows cut by the Pernicana fault system at 12 sites using cosmogenic 3He and 40Ar/39Ar techniques in order to determine the recent slip history of the fault. From the displacement-age relations, we estimate an average throw rate of ∼2.5 mm/yr over the last 15 k.y. The slip rate appears to have accelerated during the last 3.5 k.y., with displacement rates of up to ∼15 mm/yr, whereas between 3.5 and 15 ka, the throw rate averaged ∼1 mm/yr. This increase in slip rate resulted in significant changes in seismicity rates, for instance, decreasing the mean recurrence time of M ≥ 4.7 earthquakes from ∼200 to ∼20 yr. Based on empirical relationships, we attribute the variation in seismic activity on the Pernicana fault system to factors intrinsic to the system that are likely related to changes in the volcanic system. These internal factors could be fault interdependencies (such as those across the Taupo Rift, New Zealand) or they could represent interactions among magmatic, tectonic, and gravitational processes (e.g., Kīlauea volcano, Hawaii). Given their effect on earthquake recurrence intervals, these interactions need to be fully assessed in seismic hazard evaluations

    ONE-TROCAR VIDEO-ASSISTED STRIPPING TECHNIQUE FOR USE IN THE TREATMENT OF LARGE OVARIAN CYSTS IN INFANTS

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    Background Management of ovarian cysts in infants is controversial; it can be conservative or surgical, and the management is determined by the cyst''s size and sonographic features. Methods A surgical approach using a 10-mm umbilically placed operative laparoscope was taken in 3 female infants with antenatally diagnosed large, simple ovarian cysts. The contents of the cysts were partially aspirated and the cyst walls were stripped off the remaining ovarian parenchyma. No intraoperative or postoperative complications were recorded. Conclusions The one-trocar video-assisted stripping technique for large ovarian cysts in infants appears to be an ovarian-tissue-preserving procedure, and it sidesteps the disadvantages of large scars and formation of adhesions

    Nonuniversal temperature dependencies of the low-frequency ac magnetic susceptibility in high-T c superconductors

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    The complex ac magnetic susceptibilities ({\ensuremath{\chi}}_{n}={\ensuremath{\chi}}_{n}^{\ensuremath{'}}+i{\ensuremath{\chi}}_{n}^{\ensuremath{''}}) of high-Tc{T}_{c} superconductors in absence of dc fields have been studied by numerically solving the nonlinear diffusion equation for the magnetic flux, where the diffusivity is determined by the resistivity. In our approach the parallel resistor model between the creep and flux flow resistivities is used, so that the crossover between different flux dynamic processes (thermally activated flux flow, flux creep, flux flow) can naturally arise. For this reason we remark that, as the frequency increases, the presence of a different nonlinearity in different regions of the I\ensuremath{-}V characteristic determines nonuniversal temperature dependencies of the {\ensuremath{\chi}}_{n}, i.e., the {\ensuremath{\chi}}_{n} are found to be not universal functions of a frequency- and temperature-dependent single parameter. Moreover, the actual frequency-dependent behavior is also shown to be strictly related to the particular pinning model chosen for the simulations. Indeed, for large values of the reduced pinning potential (U/KTg 220)(U/KTg~220) and for increasing frequency, a transition has been observed between dynamic regimes dominated by creep and flux flow processes. On the other hand, for smaller reduced pinning potentials, a transition from the thermally activated flux flow (Taff) to the flow regime occurs. In qualitative agreement with available experimental data but in contrast with previously used simpler models, the amplitude of the peak of the imaginary part of the first harmonic is shown to be frequency dependent. Moreover the frequency dependence of its peak temperature shows large discrepancies with approximated analytical predictions. Finally, the shapes of the temperature dependencies of the higher harmonics are found to be strongly affected by the frequency

    E-PTFE (Gore-Tex) implant with or without low-dosage mitomycin-C as an adjuvant in penetrating glaucoma surgery: 2 year randomized clinical trial.

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    Purpose: To test the expanded polytetrafluoroethylene (ePTFE) as a new adjuvant in trabeculectomy. Methods: Consecutive glaucoma surgical inpatients were observed at the Department of Ophthalmology of Palermo University. Sixty patients (60 eyes)were randomly assigned to undergo trabeculectomy (T), trabeculectomy with mitomycin-C (TMMC), with ePTFE (TG) or with mitomycin-C and ePTFE (TGMMC). Postoperative visits were scheduled at 24 hr, 7 days, 1, 3, 6, 12, 18 and 24 months. Complete success and qualified success were assessed at two target intraocular pressure (IOP) levels – £21 and £17 mmHg – by Kaplan–Meier curves. Results: The postoperative IOP reduction was significant (P < 0.01) at the endpoint in all groups, with a mean IOP of 16.9 (±2.9), 16.2 (±2.7), 15.3 (±3.4) and 15.2 (±4.3) mmHg in T, TMMC, TG and TGMMC eyes, respectively. No intergroup difference was found at either IOP targets. The Kaplan–Meier curves relating to either the £21 mmHg or the £17 mmHg target IOP did not show significant intergroup differences for complete and qualified success rate. When ePTFE was used, a trend favouring the medium-term survival rate was noted. No adverse reaction to the ePTFE was present, and no membrane extrusion or conjuctival erosion were noted in any cases. Hypotony was significantly more frequent (P = 0.035) in groups without ePTFE. Moreover, the late MMC-related complications were more frequent when MMC was applied. Conclusion: Expanded polytetrafluoroethylene implant in trabeculectomy is well tolerated and could act as a filtration modulating device. Therefore, it is useful in reducing early hypotony-related complications and contributes to attaining medium-term IOP control that is comparable to the low-dosage MMC

    Esophageal atresia in newborns: a wide spectrum from the isolated forms to a full VACTERL phenotype?

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    Background: VATER association was first described in 1972 by Quan and Smith as an acronym which identifies a non-random co-occurrence of Vertebral anomalies, Anal atresia, Tracheoesophageal fistula and/or Esophageal atresia, Radial dysplasia. It is even possible to find out Cardiovascular, Renal and Limb anomalies and the acronym VACTERL was adopted, also, embodying Vascular, as single umbilical artery, and external genitalia anomalies. Methods: Data on patients with esophageal atresia (EA) with or without tracheoesophageal fistula (TEF) admitted in the Neonatal Intensive Care Unit (NICU) between January 2003 and January 2013 were evaluated for the contingent occurrence of typical VACTERL anomalies (VACTERL-type) and non tipical VACTERL anomalies (non-VACTERL-type). The inclusion criterion was the presence of EA with or without TEF plus two or more of the following additional malformations: vertebral defects, anal atresia, cardiovascular defects, renal anomalies and lower limb deformities, like radial dysplasia. Results: Among 52 patients with EA/TEF, 20 (38,4%) had isolated EA and 7 (21,8%) had a recognized etiology such a syndrome and therefore were excluded. Among 32 infants with EA and associated malformations, 15 (46,8%) had VACTERL association. The most common anomalies were congenital heart defects (73,3%), followed by vertebral anomalies (66,6%). Many patients also had additional non-VACTERL-type defects. Single umbilical artery was the most common one followed by nervous system abnormalities and anomalies of toes. Between the groups of infants with VACTERL type and non-VACTERL-type anomalies, there are several overlapping data regarding both the tipically described spectrum and the most frequently reported non-VACTERL-type malformations. Thus, it is possible to differentiate infants with a full phenotype (VACTERL full phenotype) and patients that do not meet all the criteria mentioned above, but with some homologies with the first group (VACTERL partial phenotype). Conclusion: The high frequency of non-VACTERL-type anomalies encountered in full and partial phenotype patients would suggest the need for an extension of the clinical criteria for the diagnosis of VACTERL association and also for pre- and post-operative management and follow-up in the short and long term

    Emotional expression and coping style in female breast cancer.

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    Background: The study of the relationship of emotional status and tumor etiology has been investigated in order to elaborate a multifactorial model able to provide an answer integrating the different disciplines on cancer. The aim of this work is to investigate the knowledge on the alexithymia construct, exploring the presence of such trait in women affected by mammary carcinoma and analyzing the used coping strategies. The study has also examined personal thoughts related to event control (locus of control). Method: The Toronto Alexithymia Scale, Coping Orientation to Problems Experienced, and Locus of Control questionnaires were administered to a group of 86 women aged 31\u201355 years (mean = 43.7; SD 6.57)\u2014experimental group (N = 44): women with breast cancer diagnosed in the last 6 months; control group (N = 42): women without oncologic pathology, referred at the aforementioned institutions to undergo a breast check-up. Results: According to our hypothesis and literature data, a significant presence of alexithymic subjects (36.4% versus 2.4%; v2 = 20.9; P < 0.0001) and a tendency to adopt coping strategies not focused on the problem were reported among women with mammary carcinoma. This causes incapability to act in order to actively contrast pathology-linked stress or to lower the effects. Conclusion: Our results indicate that the tendency to repress one\u2019s emotions is associated to some general schemes of reaction to stress which, when used in a dysfunctional manner (such as the attempt to ignore how threatening an event is), are maladaptive in the end
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