Radio continuum emission from knots in the DG Tau jet

Context: HH 158, the jet from the young star DG Tau, is one of the few sources of its type where jet knots have been detected at optical and X-ray wavelengths. Aims: To search, using Very Large Array observations of this source, radio knots and if detected, compare them with the optical and X-ray knots. To model the emission from the radio knots. Methods: We analyzed archive data and also obtained new Very Large Array observations of this source, as well as an optical image, to measure the present position of the knots. We also modeled the radio emission from the knots in terms of shocks in a jet with intrinsically time-dependent ejection velocities. Results: We detected radio knots in the 1996.98 and 2009.62 VLA data. These radio knots are,within error, coincident with optical knots. We also modeled satisfactorily the observed radio flux densities as shock features from a jet with intrinsic variability. All the observed radio, optical, and X-ray knot positions can be intepreted as four successive knots, ejected with a period of 4.80 years and traveling away from the source with a velocity of 198 km s$^{-1}$ in the plane of the sky. Conclusions: The radio and optical knots are spatially correlated and our model can explain the observed radio flux densities. However, the X-ray knots do not appear to have optical or radio counterparts and their nature remains poorly understood.Comment: 8 pages, 8 figures, to appear in Astronomy & Astrophysic

First detection of acceleration and deceleration in protostellar Jets? Time variability in the Chamaeleontis II outflows

Context. Kinematical and time variability studies of protostellar jets are fundamental for understanding the dynamics and the physics of these objects. Such studies remain very sporadic, since they require long baselines before they can be accomplished. Alms. We present for the first time a multi-epoch (20 years baseline) kinematical investigation of HH 52, 53, and 54 at optical and near-IR wavelengths, along with medium (optical) and high resolution (NIR) spectroscopic analyses, probing the kinematical and physical time variability conditions of the gas along the flows. Methods. By means of multi-epoch and multi-wavelength narrow-band images, we derived proper motions (PMs), tangential velocities, velocity and flux variability of the knots. Radial velocities and physical parameters of the gas were derived from spectroscopy. Finally, spatial velocities and inclination of the flows were obtained by combining both imaging and spectroscopy. Results. The PM analysis reveals three distinct, partially overlapping outflows. Spatial velocities of the knots vary from 50 km s -1 to 120 km s-1. The inclinations of the three flows are 58 ± 3°, 84 ± 2°, and 67 ± 3° (HH 52, HH 53, and HH 54 flows, respectively). In 20 years, about 60% of the observed knots show some degree of flux variability. Our set of observations apparently indicates acceleration and deceleration in a variety of knots along the jets. For about 20% of the knots, mostly coincident with working surfaces or interacting knots along the flows, a relevant variability in both flux and velocity is observed. We argue that both variabilities are related and that all or part of the kinetic energy lost by the interacting knots is successively radiated. The physical parameters derived from the diagnostics are quite homogeneous along and among the three outflows. The analysis indicates the presence of very light (NH � 103 cm-3), ionised (Te,. � 0.2-0.6), and hot (Te � 14000-26000 K) flows, impacting a denser medium. Several knots are deflected, especially in the HH 52 flow. At least for a couple of them (HH 54 G and GO), the deflection originates from the collision of the two. For the more massive parts of the flow, the deflection is likely the result of the flow collision with a dense cloud or with clumps. Finally, we discuss the possible driving sources of the flows. ©ESO 2009

Issues of ideology in English language education worldwide: an overview

The relatively limited consideration of ideology in mainstream theory and research of teaching the English language to speakers of other languages has arguably prevented the problematization of many taken-for-granted perceptions and practices of the field. In this article I attempt to bring part of this marginalized body of scholarship on issues of ideology in the area of English language teaching (ELT) to highlight its potential insights for the field. The article sets out from a view of ideology as the most fundamental beliefs in any social practice, which may provide a less-formidable conception of the term and lessen the divergence among the minority of ELT researchers and professionals that do concern themselves with ideology. Then, after a brief sketch of the notion of ideology of language (education), I present an overview of aspects of this marginal but vibrant stream of thought on issues of ideology in ELT worldwide. Overall, the discussion is aimed to act as a call for the further understanding and embracement of sociopolitically-sensitive and ideologically-informed approaches to ELT theory, research, and practice

Stylized facts of intraday precious metals

This paper examines the stylized facts, correlation and interaction between volatility and returns at the 5-minute frequency for gold, silver, platinum and palladium from May 2000 to April 2015. We study the full sample period, as well as three subsamples to determine how high-frequency data of precious metals have developed over time. We find that over the full sample, the number of trades has increased substantially over time for each precious metal, while the bid-ask spread has narrowed over time, indicating an increase in liquidity and price efficiency. We also find strong evidence of periodicity in returns, volatility, volume and bid- ask spread. Returns and volume both experience strong intraday periodicity linked to the opening and closing of major markets around the world while the bid-ask spread is at its low- est when European markets are open. We also show a bilateral Granger causality between returns and volatility of each precious metal, which holds for the vast majority subsamples

The PAV trial: Does lactobacillus prevent post-antibiotic vulvovaginal candidiasis? Protocol of a randomised controlled trial [ISRCTN24141277]

BACKGROUND: Complementary and alternative medicines are used by many consumers, and increasingly are being incorporated into the general practitioner's armamentarium. Despite widespread usage, the evidence base for most complementary therapies is weak or non-existent. Post-antibiotic vulvovaginitis is a common problem in general practice, for which complementary therapies are often used. A recent study in Melbourne, Australia, found that 40% of women with a past history of vulvovaginitis had used probiotic Lactobacillus species to prevent or treat post-antibiotic vulvovaginitis. There is no evidence that this therapy is effective. This study aims to test whether oral or vaginal lactobacillus is effective in the prevention of post-antibiotic vulvovaginitis. METHODS/DESIGN: A randomised placebo-controlled blinded 2 × 2 factorial design is being used. General practitioners or pharmacists approach non-pregnant women, aged 18–50 years, who present with a non-genital infection requiring a short course of oral antibiotics, to participate in the study. Participants are randomised in a four group factorial design either to oral lactobacillus powder or placebo and either vaginal lactobacillus pessaries or placebo. These interventions are taken while on antibiotics and for four days afterwards or until symptoms of vaginitis develop. Women self collect a vaginal swab for culture of Candida species and complete a survey at baseline and again four days after completing their study medications. The sample size (a total of 496 – 124 in each factorial group) is calculated to identify a reduction of half in post-antibiotic vulvovaginitis from 23%, while allowing for a 25% drop-out. An independent Data Monitoring Committee is supervising the trial. Analysis will be intention-to-treat, with two pre-specified main comparisons: (i) oral lactobacillus versus placebo and (ii) vaginal lactobacillus versus placebo

Future directions in international financial integration research. A crowdsourced perspective

This paper is the result of a crowdsourced effort to surface perspectives on the present and future direction of international finance. The authors are researchers in financial economics who attended the INFINITI 2017 conference in the University of Valencia in June 2017 and who participated in the crowdsourcing via the Overleaf platform. This paper highlights the actual state of scientific knowledge in a multitude of fields in finance and proposes different directions for future research

High frequency trading strategies, market fragility and price spikes: an agent based model perspective

Given recent requirements for ensuring the robustness of algorithmic trading strategies laid out in the Markets in Financial Instruments Directive II, this paper proposes a novel agent-based simulation for exploring algorithmic trading strategies. Five different types of agents are present in the market. The statistical properties of the simulated market are compared with equity market depth data from the Chi-X exchange and found to be significantly similar. The model is able to reproduce a number of stylised market properties including: clustered volatility, autocorrelation of returns, long memory in order flow, concave price impact and the presence of extreme price events. The results are found to be insensitive to reasonable parameter variations

The vaginal Bifidobacterium flora in women of reproductive age

Recent studies have shown that certain lactobacilli strains have the ability to interfere with the adherence and growth of uropathogenic bacteria. This interaction if believed to be important in the maintenance of a normal urogenital flora and in the prevention of infection in females. In the present study, Lactobacillus casei ssp. rhamnosus GR-1 and Lactobacillus acidophilus 76 were found to exert an inhibitory effect on pyelonephritogenic mutant Escherichia coli Hu 734 and E. coli ATCC 25922. The bioactivity of the inhibitor produced by strain GR-1 was retained under pH buffered conditions and was bactericidal. The bioactive substance was heat labile, not precipitated by up to 80% ammonium sulphate, and extractable in chloroform. The data indicated that the inhibitor is not lactic acid or hydrogen peroxide and has a molecular weight greater than 12 000 - 14 000. Human urine supported production of the inhibitor and reduced and delayed outgrowth of the E. coli. The ability of L. casei GR-1 and possibly other lactobacilli strains to produce inhibitors or uropathogenic bacteria may have clinical importance and significance in the microbial ecology of the urogenital tract