Observational evidences on the modulation of the South American Low Level Jet east of the Andes according the ENSO variability

The differences on the phase and wavelength of the quasi-stationary waves over the South America generated by El Niño (EN) and La Niña (LN) events seem to affect the daily evolution of the South American Low Level Jet east of the Andes (SALLJ). For the austral summer period of 1977–2004 the SALLJ episodes detected according to Bonner criterion 1 show normal to above-normal frequency in EN years, and in LN years the episodes show normal to below-normal frequency. <br><br> During EN and LN years the SALLJ episodes were associated with positive rainfall anomalies over the La Plata Basin, but more intense during LN years. During EN years the increase in the SALLJ cases were associated to intensification of the Subtropical Jet (SJ) around 30° S and positive Sea Level Pressure (SLP) anomalies over the western equatorial Atlantic and tropical South America, particularly over central Brazil. This favored the intensification of the northeasterly trade winds over the northern continent and it channeled by the Andes mountain to the La Plata Basin region where negative SLP are found. The SALLJ cases identified during the LN events were weaker and less frequent when compared to those for EN years. In this case the SJ was weaker than in EN years and the negative SLP anomalies over the tropical continent contributed to the inversion of the northeasterly trade winds. Also a southerly flow anomaly was generated by the geostrophic balance due to the anomalous blocking over southeast Pacific and the intense cyclonic transient over the southern tip of South America. As result the warm tropical air brought by the SALLJ encounters the cold extratropical air from the southerly winds over the La Plata basin. This configuration can increase the conditional instability over the La Plata basin and may explain the more intense positive rainfall anomalies in SALLJ cases during LN years than in EN years

Paediatric Recurrent Ear, Nose and Throat Infections and Complications: Can We Do More?

Recurrent respiratory tract infections (rRTIs), of which there are three main groups—otitis media, tonsillitis and sinusopathies—are very common in paediatric populations and are associated with significant morbidity and mortality due to complications. These infections substantially reduce quality of life for paediatric patients and their families and are a significant personal, medical and economic burden on the patients, the patients’ families and the healthcare system. Most rRTIs are of viral origin; however, indiscriminate use of antibiotics in their treatment has led to development of bacterial resistance. Effective management of rRTIs to reduce the burden of disease and to avoid overuse of antibiotics has become a great therapeutic challenge. New strategies for the management of paediatric rRTIs include focus on prevention using non-specific immunomodulators to boost the body’s natural defences against infection and to downregulate infection- and allergen-induced airway inflammation. The oral immunomodulator, OM-85, a bacterial lysate, acts on the innate and adaptive branches of the immune system, conferring protection against viral and bacterial infections, and controls inflammation, thereby reducing tissue damage. OM-85 has demonstrated good tolerability and clinical efficacy in reducing the number and duration of RTIs in children with recurrent airway infections. It has also been reported to reduce the use of concomitant medications, including antibiotics, time to cure and school absenteeism. OM-85 is efficacious and well tolerated when administered concomitantly with inactivated influenza vaccine (IIV) and has been shown to reduce wheezing attacks induced by RTI in young children. Clinical results show that the greater the risk of rRTIs, the greater the benefit with OM-85. OM-85 may be considered a promising tool to add to the limited armamentarium of the ear, nose and throat (ENT) physician dealing with rRTIs and their complications, such as recurrent wheeze and asthma inception

Observations of Extrasolar Planets During the non-Cryogenic Spitzer Space Telescope Mission

Precision infrared photometry from Spitzer has enabled the first direct studies of light from extrasolar planets, via observations at secondary eclipse in transiting systems. Current Spitzer results include the first longitudinal temperature map of an extrasolar planet, and the first spectra of their atmospheres. Spitzer has also measured a temperature and precise radius for the first transiting Neptune-sized exoplanet, and is beginning to make precise transit timing measurements to infer the existence of unseen low mass planets. The lack of stellar limb darkening in the infrared facilitates precise radius and transit timing measurements of transiting planets. Warm Spitzer will be capable of a precise radius measurement for Earth-sized planets transiting nearby M-dwarfs, thereby constraining their bulk composition. It will continue to measure thermal emission at secondary eclipse for transiting hot Jupiters, and be able to distinguish between planets having broad band emission versus absorption spectra. It will also be able to measure the orbital phase variation of thermal emission for close-in planets, even non-transiting planets, and these measurements will be of special interest for planets in eccentric orbits. Warm Spitzer will be a significant complement to Kepler, particularly as regards transit timing in the Kepler field. In addition to studying close-in planets, Warm Spitzer will have significant application in sensitive imaging searches for young planets at relatively large angular separations from their parent stars.Comment: 12 pages, 7 figures, to appear in "Science Opportunities for the Warm Spitzer Mission

Infrared Observations of the Helix Planetary Nebula

We have mapped the Helix (NGC 7293) planetary nebula (PN) with the IRAC instrument on the Spitzer Space Telescope. The Helix is one of the closest bright PNs and therefore provides an opportunity to resolve the small-scale structure in the nebula. The emission from this PN in the 5.8 and 8 μm IRAC bands is dominated by the pure rotational lines of molecular hydrogen, with a smaller contribution from forbidden line emission such as [Ar III] in the ionized region. The IRAC images resolve the "cometary knots," which have been previously studied in this PN. The "tails" of the knots and the radial rays extending into the outer regions of the PN are seen in emission in the IRAC bands. IRS spectra on the main ring and the emission in the IRAC bands are consistent with shock-excited H_2 models, with a small (~10%) component from photodissociation regions. In the northeast arc, the H_2 emission is located in a shell outside the Hα emission

Penetration characteristics of a liquid droplet impacting on a narrow gap:Experimental and numerical analysis

Experimentalists are limited in the amount of information they can derive from drop impact experiments on porous surfaces because of the short timescales involved and the normally opaque nature of porous materials. Numerical simulations can supplement experiments and provide researchers with previously unattainable information such as velocity and pressure profiles, and quantification of fluid volume flow rates into the pores. Ethanol drops, 2.0 mm in diameter, are impacted on a narrow gap at Weber numbers that match the impact of water drops, also 2.0 mm in diameter, on the same gap size in a previous study. The experiments show the ethanol drops cleaving at all Weber numbers tested, while the water drops completely enter the gap at low Weber numbers and only cleave at higher Weber numbers. A volume of fluid numerical model of the experiments is constructed in OpenFOAM and used to probe the interior of the drops during impact. For the water drop, a high-pressure region fills the drop during impact which continuously drives liquid into the gap. For the ethanol drops, the high-pressure region is smaller and quickly attenuates, which results in a near-zero vertical velocity at the entrance of the gap. Compared to water, the lower surface tension of ethanol causes these drops to spread further upon impact, recoil less, and overall have less liquid over the gap, which promotes cleaving. Against a superficial thought, when the penetration of liquids into porous materials is to be maximized, a higher surface tension liquid is therefore desirable