1,203 research outputs found

    Nucleation Induced Undulative Instability in Thin Films of nCB Liquid Crystals

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    A surface instability is reported in thin nematic films of 5CB and 8CB, occurring near the nematic--isotropic phase transition. Although this instability leads to patterns reminiscent of spinodal dewetting, we show that it is actually based on a nucleation mechanism. Its characteristic wavelength does not depend markedly on film thickness, but strongly on the heating rate.Comment: 4 pages, 5 figure

    Seismic strain and seismogenic stress regimes in the crust of the southern Tyrrhenian region

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    An investigation has been performed to identify and characterize the seismic deformation zones active over the last decades in the region of Italy that has experienced the strongest seismicity during the last centuries. The study is based on the estimate of hypocenter locations, fault plane solutions, seismogenic stress and seismic strain tensor orientations carried out using the entire dataset of the national and local seismic networks, and the recently improved three-dimensional (3D) crustal velocity model of the study area. A series of simulation tests have been performed to evaluate the significance of the earthquake space distribution obtained and whether it was influenced by network geometry problems related to the sea and the lack of ocean bottom seismometers. In the sectors where hypocentral location was synthetically proved to be reliable, space distributions of earthquakes located with epicenter and focal depth errors less than 3 and 4 km, respectively, have been compared with local geology in order to identify seismogenic faults. The dataset of 32 fault plane solutions estimated with fault parameter errors less than 20° has been used to investigate space variations of seismogenic stress and seismic strain orientations over the study area. Stress was found to be uniform in the Messina Strait and southern Calabria where inversion of the available set of 11 fault plane solutions showed clear evidence of an extensional regime. The different orientations of the minimum compressive stress and strain found in this sector, together with the information available on local geology and tectonics, lead us to propose that the seismicity occurring over the last decades in the Messina Strait and southern Calabria was not in general produced at the main faults, but at minor faults activated by the main tectonic stress field acting in the area. To the west, in the sector including western Etna, the Nebrodi chain and the western Aeolian Islands, analysis of the available set of 16 fault plane solutions revealed a certain degree of stress heterogeneity with an apparent prevalence of north–south compression. This east to west change of stress–strain regimes is evaluated in the light of current hypotheses regarding the geodynamics of the study region

    Localizzazione probabilistica 3D (NonLinLoc) applicata all’area calabro-peloritana

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    Sono presentati e discussi i risultati preliminari relativi ad una ri-localizzazione probabilistica non-lineare 3D dei terremoti dell’area compresa tra il Tirreno meridionale e l’Arco Calabro-Peloritano (Italia meridionale). Scopo del lavoro è dimostrare che l’applicazione di un’approccio probabilistico non-lineare nella localizzazione dei terremoti può fornire dei risultati più accurati ai fini della sorveglianza, ovviando al problema degli outlier, rispetto alle tecniche di localizzazione lineari (e.g. Hypoellipse), che minimizzano simultaneamente tutti i residui tra fasi osservate e calcolate. Il programma utilizzato è NonLinLoc [Lomax, et al., 2000; Lomax, et al., 2001; Lomax, 2005; http://www.alomax.net/nlloc; NonLinLoc di seguito] il quale permette di effettuare un’efficiente ricerca globale dello spazio dei parametri ipocentrali (coordinate spaziali e tempo origine) ottenendo una stima della funzione densità di probabilità (pdf, probability density function) a posteriori. La pdf fornisce una descrizione completa della localizzazione e delle sue incertezze; il campionamento dello spazio dei parametri ipocentrali è stato fatto mediante la tecnica Oct-tree nella regione compresa tra 37.75 e 39.40 N in latitudine e tra 14.80 e 16.80 E in longitudine, e utilizzando tutti gli eventi con profondità H ≤30 km. La struttura dell’Oct-tree è stata imposta in 100,000 celle ed un insieme di queste celle viene poi salvata in modo da poter rappresentare graficamente la pdf mediante nubi di punti a diversa densità. Il dataset utilizzato per le nostre analisi è composto da 1,304 terremoti, di 1.0<M<4.3, registrati nel periodo compreso tra il 1994 e il 2006; il modello di velocità 3D adottato è stato ottenuto da Barberi et al., 2008 [poster presentato a questo convegno] invertendo lo stesso dataset, mediante l’utilizzo del software TomoDD. I risultati ottenuti sono stati confrontati sia con le localizzazioni 1D (Hypoellipse) che con quelle 3D. Si evidenzia una maggiore clusterizzazione degli eventi e, soprattutto, un evidente miglioramento della qualità delle localizzazioni utilizzando il modello di velocità crostale 3D. Per cui riteniamo che, l’applicazione del metodo probabilistico associato ad un buon modello di velocità 3D, può essere utilizzato ai fini di sorveglianza

    Infectious diseases and vaccination strategies: how to protect the "unprotectable"?

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    Introduction. The circulation of infectious diseases puts small infants too young to be vaccinated at risk of morbidity and mortality, often requiring prolonged hospitalization. Material and Methods. We have reviewed the medical records of children not eligible for vaccination because of age, admitted to hospital for pertussis, measles, or varicella from February 1, 2010, till February 1, 2012. Results. Of the case records scrutinized, 21 were hospitalized for pertussis, 18 for measles, and 32 for varicella. Out of them, 42%, 66%, and 78% diagnosed with, respectively, pertussis, measles, and varicella had a complicated course of the disease. Discussion. To avoid infectious disease circulation, childhood immunization strategies should be adopted, such as vaccination of healthcare givers, adult household contacts, and parents planning to have, or who have had, a newborn baby

    Tectonics and seismicity of the Tindari Fault System, southern Italy: Crustal deformations at the transition between ongoing contractional and extensional domains located above the edge of a subducting slab

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    The Tindari Fault System (southern Tyrrhenian Sea, Italy) is a regional zone of brittle deformation located at the transition between ongoing contractional and extensional crustal compartments and lying above the western edge of a narrow subducting slab. Onshore structural data, an offshore seismic reflection profile, and earthquake data are analyzed to constrain the present geometry of the Tindari Fault System and its tectonic evolution since Neogene, including the present seismicity. Results show that this zone of deformation consists of a broad NNW trending system of faults including sets of right-lateral, left-lateral, and extensional faults as well as early strike-slip faults reworked under late extension. Earthquakes and other neotectonic data provide evidence that the Tindari Fault System is still active in the central and northern sectors and mostly accommodates extensional or rightlateral transtensional displacements on a diffuse array of faults. From these data, a multiphase tectonic history is inferred, including an early phase as a right-lateral strike-slip fault and a late extensional reworking under the influence of the subductionrelated processes, which have led to the formation of the Tyrrhenian back-arc basin. Within the present, regional, geodynamic context, the Tindari Fault System is interpreted as an ongoing accommodation zone between the adjacent contractional and extensional crustal compartments, these tectonic compartments relating to the complex processes of plate convergence occurring in the region. The Tindari Fault System might also be included in an incipient, oblique-extensional, transfer zone linking the ongoing contractional belts in the Calabrian-Ionian and southern Tyrrhenian compartments

    Localizzazione probabilistica 3D (NonLinLoc) applicata all’area calabro-peloritana

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    Sono presentati e discussi i risultati preliminari relativi ad una ri-localizzazione probabilistica non-lineare 3D dei terremoti dell’area compresa tra il Tirreno meridionale e l’Arco Calabro-Peloritano (Italia meridionale). Scopo del lavoro è dimostrare che l’applicazione di un’approccio probabilistico non-lineare nella localizzazione dei terremoti può fornire dei risultati più accurati ai fini della sorveglianza, ovviando al problema degli outlier, rispetto alle tecniche di localizzazione lineari (e.g. Hypoellipse), che minimizzano simultaneamente tutti i residui tra fasi osservate e calcolate. Il programma utilizzato è NonLinLoc [Lomax, et al., 2000; Lomax, et al., 2001; Lomax, 2005; http://www.alomax.net/nlloc; NonLinLoc di seguito] il quale permette di effettuare un’efficiente ricerca globale dello spazio dei parametri ipocentrali (coordinate spaziali e tempo origine) ottenendo una stima della funzione densità di probabilità (pdf, probability density function) a posteriori. La pdf fornisce una descrizione completa della localizzazione e delle sue incertezze; il campionamento dello spazio dei parametri ipocentrali è stato fatto mediante la tecnica Oct-tree nella regione compresa tra 37.75 e 39.40 N in latitudine e tra 14.80 e 16.80 E in longitudine, e utilizzando tutti gli eventi con profondità H ≤30 km. La struttura dell’Oct-tree è stata imposta in 100,000 celle ed un insieme di queste celle viene poi salvata in modo da poter rappresentare graficamente la pdf mediante nubi di punti a diversa densità. Il dataset utilizzato per le nostre analisi è composto da 1,304 terremoti, di 1.0<M<4.3, registrati nel periodo compreso tra il 1994 e il 2006; il modello di velocità 3D adottato è stato ottenuto da Barberi et al., 2008 [poster presentato a questo convegno] invertendo lo stesso dataset, mediante l’utilizzo del software TomoDD. I risultati ottenuti sono stati confrontati sia con le localizzazioni 1D (Hypoellipse) che con quelle 3D. Si evidenzia una maggiore clusterizzazione degli eventi e, soprattutto, un evidente miglioramento della qualità delle localizzazioni utilizzando il modello di velocità crostale 3D. Per cui riteniamo che, l’applicazione del metodo probabilistico associato ad un buon modello di velocità 3D, può essere utilizzato ai fini di sorveglianza

    Implicating factors in the increase in cases of central precocious puberty (CPP) during the COVID-19 pandemic: Experience of a tertiary centre of pediatric endocrinology and review of the literature

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    Sexual development is a complex mechanism activated by the hypothalamic-pituitary-gonadal axis. Over the last one hundred years there has been a decline in the age at puberty onset in industrialised countries. Some Italian studies showed an increase in diagnoses of Central Precocious Puberty (CPP) during the COVID-19 pandemic. It is thus supposed that in this period there was an increased impact of factors that can influence pubertal development. Our retrospective monocentric study aimed to confirm the existence of this phenomenon and analysed possible related factors. We retrospectively evaluated clinical, laboratory, radiological and ultrasound (US) data of 154 girls referred to our Tertiary Centre of Paediatric Endocrinology from January 2019 to April 2021 for different forms of Precocious Puberty. We subdivided the cases into subgroups according to the final diagnosis: CPP, Early Puberty (EP), isolated thelarche and isolated pubarche. The observation period was subdivided into: Period 1, before lockdown (1 January 2019 - 8 March 2020) and Period 2, lockdown and the following months (9 March 2020 - 30 April 2021). Period 2 was further divided into "restrictive lockdown period" (Period 2.1) (March 2020 - 14 June 2020, in which the schools were closed) and "less restrictive lockdown period" (Period 2.2) (15 June 2020 - 30 April 2021). We analysed data regarding the use of electronic devices before and during lockdown in a group of girls with CPP diagnosed in Period 2 and we compared the data with that of a control group. Our data show an increase in the number of new diagnoses of CPP during lockdown and in the following months, compared with the previous period. We also detected a higher use of PCs and smartphones in girls with CPP diagnosed in Period 2, compared with the control group. The percentage of the presence of endometrial rhyme detected during the pelvic ultrasound was higher in girls with CPP in Period 2, compared with the previous period. Based on our data we assume there was an environmental effect on pubertal timing that calls our attention to factors such as food, use of electronic devices and stress. We will need further studies to better understand this data

    Optimization of the appearance quality in CO2 processed ready-to-eat carrots through image analysis

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    A high-pressure CO2 process applied to ready-to-eat food products guarantees an increase of both their microbial safety and shelf-life. However, the treatment often produces unwanted changes in the visual appearance of products depending on the adopted process conditions. Accordingly, the alteration of the visual appearance influences consumers’ perception and acceptability. This study aims at identifying the optimal treatment conditions in terms of visual appearance by using an artificial vision system. The developed methodology was applied to fresh-cut carrots (Daucus carota) as the test product. The results showed that carrots packaged in 100% CO2 and subsequently treated at 6 MPa and 40◦C for 15 min maintained an appearance similar to the fresh product for up to 7 days of storage at 4◦C. Mild appearance changes were identified at 7 and 14 days of storage in the processed products. Microbiological analysis performed on the optimal treatment condition showed the microbiological stability of the samples up to 14 days of storage at 4◦C. The artificial vision system, successfully applied to the CO2 pasteurization process, can easily be applied to any food process involving changes in the appearance of any food product
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