Three dimensional imaging of short pulses

We exploit a slightly noncollinear second-harmonic cross-correlation scheme to map the 3D space-time intensity distribution of an unknown complex-shaped ultrashort optical pulse. We show the capability of the technique to reconstruct both the amplitude and the phase of the field through the coherence of the nonlinear interaction down to a resolution of 10 $\mu$m in space and 200 fs in time. This implies that the concept of second-harmonic holography can be employed down to the sub-ps time scale, and used to discuss the features of the technique in terms of the reconstructed fields.Comment: 16 pages, 6 figure

Dark Matter detection via lepton cosmic rays

Recent observations of lepton cosmic rays, coming from the PAMELA and FERMI experiments, have pushed our understanding of the interstellar medium and cosmic rays sources to unprecedented levels. The imprint of dark matter on lepton cosmic rays is the most exciting explanation of both PAMELA's positron excess and FERMI's total flux of electrons. Alternatively, supernovae are astrophysical objects with the same potential to explain these observations. In this work, we present an updated study of the astrophysical sources of lepton cosmic rays and the possible trace of a dark matter signal on the positron excess and total flux of electrons.Comment: 6 pages and 3 figures. Proceedings for PASCOS 2010, Valencia, Spai

Fire analysis of timber composite beams with interlayer slip

The purpose of this paper is to model the behaviour of timber composite beams with interlayer slip, when simultaneously exposed to static loading and fire. A transient moisture-thermal state of a timber beam is analysed by the Luikov equations, and mechanical behaviour of timber composite beam is modelled by Reissner's kinematic equations. The model can handle layers of different materials. Material properties are functions of temperature. The thermal model is validated against the experimental data presented in the literature. Generally, the model provides excellent agreement with the experimental data. It is shown that the material properties of timber play an important role in the fire resistance analysis of timber structures when exposed to fire

Nafion-TiO2 composite DMFC membranes: Physico-chemical properties of the filier versus electrochemical performance

TiO2 nanometric powders were prepared via a sol-gel procedure and calcined at various temperatures to obtain different surface and bulk properties. The calcined powders were used as fillers in composite Nafion membranes for application in high temperature direct methanol fuel cells (DMFCs). The powder physico-chemical properties were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and pH measurements. The observed characteristics were correlated to the DMFC electrochemical behaviour. Analysis of the high temperature conductivity and DMFC performance reveals a significant influence of the surface characteristics of the ceramic oxide, such as oxygen functional groups and surface area, on the membrane electrochemical behaviour. A maximum DMFC power density of 350 mW cm-2 was achieved under oxygen feed at 145°C in a pressurized DMFC (2.5 bar, anode and cathode) equipped with TiO2 nano-particles based composite membranes. © 2004 Elsevier Ltd. All rights reserved

Hybrid supramolecular gels of Fmoc-F/halloysite nanotubes: systems for sustained release of camptothecin

Supramolecular gel hybrids obtained by self-assembly of Fmoc-L-phenylalanine (Fmoc-F) in the presence of functionalized halloysite nanotubes (f-HNT) were obtained in biocompatible solvents and employed as carriers for the delivery of camptothecin (CPT) molecules. The synthesis of the new f-HNT material as well as its characterization are described. The properties of the hybrid hydrogels and organogels were analyzed by several techniques. The presence of small amounts of f-HNT allows good dispersion of the tubes and the subsequent formation of homogeneous gels. The experimental results show that f-HNT functions only as an additive in the hybrid gels and does not demonstrate gelator behavior. The in vitro kinetic release from both f-HNT/CPT and Fmoc-F/f-HNT/CPT was studied in media that imitates physiological conditions, and the factors controlling the release process were determined and discussed. Furthermore, the antiproliferative in vitro activities of the gels were evaluated towards human cervical cancer HeLa cells. A comparison of data collected in both systems shows the synergistic action of f-HNT and the gel matrix in controlling the release of CPT in the media and maintaining the drug in its active form. Finally, a comparison with pristine HNT is also reported. This study suggests a suitable strategy to obtain two-component gel hybrids based on nanocarriers with controlled drug carrier capacity for biomedical applications

THE VALUE OF DIAGNOSTIC ULTRASOUND FOR DETECTING OCCULT INGUINAL HERNIA IN PATIENTS WITH GROIN PAIN

Aims: chronic groin pain caused by an occult hernia can be a difficult clinical diagnosis and may require additional investiga- tive modalities. The aim of this study was to demonstrate the accuracy of ultrasound in diagnosing occult hernia in patients with recurrent inguinal pain and a negative clinical examination. Patients and methods: over a period of three years, a total of 76 patients were referred for ultrasound examination with clini- cally suspected occult inguinal hernia. Patients with positive US scans were offered surgery, while those with negative US findings were offered further imaging or other diagnostic tests. The ultrasound examination of the inguinal region was conducted using a 5- 10 MHz linear probe. The scan was performed with the patient in the supine and erect positions, in a relaxed state, as well as during coughing and during a Valsalva manoeuvre. Results: overall, ultrasound diagnosed 31 inguinal hernias and all 31 patients with positive scans underwent surgery. Surgery confirmed the ultrasound diagnosis in 30 patients, having only 1/31 no hernia at operation (100% ultrasound sensitivity and 96.9% specificity). Patients undergoing surgery showed complete symptom resolution at a three-month follow-up. Conclusions: this study confirms that ultrasound is capable of accurately diagnosing groin hernia and this may justify its use in patients with chronic groin pain due to a suspected occult herni

A review of wildland fire spread modelling, 1990-present, 1: Physical and quasi-physical models

In recent years, advances in computational power and spatial data analysis (GIS, remote sensing, etc) have led to an increase in attempts to model the spread and behaviour of wildland fires across the landscape. This series of review papers endeavours to critically and comprehensively review all types of surface fire spread models developed since 1990. This paper reviews models of a physical or quasi-physical nature. These models are based on the fundamental chemistry and/or physics of combustion and fire spread. Other papers in the series review models of an empirical or quasi-empirical nature, and mathematical analogues and simulation models. Many models are extensions or refinements of models developed before 1990. Where this is the case, these models are also discussed but much less comprehensively.Comment: 31 pages + 8 pages references + 2 figures + 5 tables. Submitted to International Journal of Wildland Fir

Reactivity during bench-scale combustion of biomass fuels for carbon capture and storage applications

Reactivities of four biomass samples were investigated in four combustion atmospheres using non-isothermal thermogravimetric analysis (TGA) under two heating rates. The chosen combustion atmospheres reflect carbon capture and storage (CCS) applications and include O2O2 and CO2CO2-enrichment. Application of the Coats–Redfern method assessed changes in reactivity. Reactivity varied due to heating rate: the reactivity of char oxidation was lower at higher heating rates while devolatilisation reactions were less affected. In general, and particularly at the higher heating rate, increasing [O2O2] increased combustion reactivity. A lesser effect was observed when substituting N2N2 for CO2CO2 as the comburent; in unenriched conditions this tended to reduce char oxidation reactivity while in O2O2-enriched conditions the reactivity marginally increased. Combustion in a typical, dry oxyfuel environment (30% O2O2, 70% CO2CO2) was more reactive than in air in TGA experiments. These biomass results should interest researchers seeking to understand phenomena occurring in larger scale CCS-relevant experiments

THE VALUE OF DIAGNOSTIC ULTRASOUND FOR DETECTING OCCULT INGUINAL HERNIA IN PATIENTS WITH GROIN PAIN

Aims: chronic groin pain caused by an occult hernia can be a difficult clinical diagnosis and may require additional investiga- tive modalities. The aim of this study was to demonstrate the accuracy of ultrasound in diagnosing occult hernia in patients with recurrent inguinal pain and a negative clinical examination. Patients and methods: over a period of three years, a total of 76 patients were referred for ultrasound examination with clini- cally suspected occult inguinal hernia. Patients with positive US scans were offered surgery, while those with negative US findings were offered further imaging or other diagnostic tests. The ultrasound examination of the inguinal region was conducted using a 5- 10 MHz linear probe. The scan was performed with the patient in the supine and erect positions, in a relaxed state, as well as during coughing and during a Valsalva manoeuvre. Results: overall, ultrasound diagnosed 31 inguinal hernias and all 31 patients with positive scans underwent surgery. Surgery confirmed the ultrasound diagnosis in 30 patients, having only 1/31 no hernia at operation (100% ultrasound sensitivity and 96.9% specificity). Patients undergoing surgery showed complete symptom resolution at a three-month follow-up. Conclusions: this study confirms that ultrasound is capable of accurately diagnosing groin hernia and this may justify its use in patients with chronic groin pain due to a suspected occult herni