New aperture photometry of QSO 0957+561; application to time delay and microlensing

We present a re-reduction of archival CCD frames of the doubly imaged quasar 0957+561 using a new photometry code. Aperture photometry with corrections for both cross contamination between the quasar images and galaxy contamination is performed on about 2650 R-band images from a five year period (1992-1997). From the brightness data a time delay of 424.9 +/- 1.2 days is derived using two different statistical techniques. The amount of gravitational microlensing in the quasar light curves is briefly investigated, and we find unambiguous evidence of both long term and short term microlensing. We also note the unusual circumstance regarding time delay estimates for this gravitational lens. Estimates by different observers from different data sets or even with the same data sets give lag estimates differing by typically 8 days, and error bars of only a day or two. This probably indicates several complexities where the result of each estimate depends upon the details of the calculation.Comment: 14 pages, 16 figures (several in color

Estimating sunspot number

An empirical method is developed to predict certain parameters of future solar activity cycles. Sunspot cycle statistics are examined, and curve fitting and linear regression analysis techniques are utilized

Three photometric methods tested on ground-based data of Q 2237+0305

The Einstein Cross, Q~2237+0305, has been photometrically observed in four bands on two successive nights at NOT (La Palma, Spain) in October 1995. Three independent algorithms have been used to analyse the data: an automatic image decomposition technique, a CLEAN algorithm and the new MCS deconvolution code. The photometric and astrometric results obtained with the three methods are presented. No photometric variations were found in the four quasar images. Comparison of the photometry from the three techniques shows that both systematic and random errors affect each method. When the seeing is worse than 1.0", the errors from the automatic image decomposition technique and the Clean algorithm tend to be large (0.04-0.1 magnitudes) while the deconvolution code still gives accurate results (1{sigma} error below 0.04) even for frames with seeing as bad as 1.7". Reddening is observed in the quasar images and is found to be compatible with either extinction from the lensing galaxy or colour dependent microlensing. The photometric accuracy depends on the light distribution used to model the lensing galaxy. In particular, using a numerical galaxy model, as done with the MCS algorithm, makes the method less seeing dependent. Another advantage of using a numerical model is that eventual non-homogeneous structures in the galaxy can be modeled. Finally, we propose an observational strategy for a future photometric monitoring of the Einstein Cross.Comment: 9 pages, accepted for publication in A&

Winter Survival and Physiology of Contrasting Fall Dormancy Selections of Alfalfa

Our objective was to determine the physiological changes that accompany selection from within a germplasm for contrasting fall dormancy reaction. Selection for greater fall dormancy improved winter survival of CUF 101 from 1 to 93%. The more fall dormant CUF 101 had higher sugar concentrations in buds and roots. Roots of the more fall dormant CUF 101 also contained higher soluble protein concentrations when compared to the other CUF 101 germplasms. Root protein extracts obtained in Dec. from the more fall dormant CUF 101 contained at least one polypeptide not found in protein extracts of the other CUF 101 germplasms. Efforts to characterize changes in gene expression that accompany winter hardening of these germplasms are underway

Increased host investment in extrafloral nectar (EFN) improves the efficiency of a mutualistic defensive service

Extrafloral nectar (EFN) plays an important role as plant indirect defence through the attraction of defending ants. Like all rewards produced in the context of a mutualism, however, EFN is in danger of being exploited by non-ant consumers that do not defend the plant against herbivores. Here we asked whether plants, by investing more in EFN, can improve their indirect defence, or rather increase the risk of losing this investment to EFN thieves. We used the obligate plant-ant Acacia-Pseudomyrmex system and examined experimentally in the field during the dry and the rainy seasons how variations in EFN secretion are related to (i) ant activity, to (ii) the ant-mediated defence against herbivores and (iii) the exploitation of EFN by non-ant consumers. Extrafloral investment enhanced ant recruitment and was positively related to the ant mediated defence against herbivores. The ant-mediated protection from exploiters also increased in proportion to the nectar sugar concentration. Although the daily peak of EFN production coincided with the highest activity of EFN thieves, Pseudomyrmex ferrugineus ants protected this resource effectively from exploiters. Nevertheless, the defensive effects by ants differed among seasons. During the dry season, plants grew slower and secreted more EFN than in the rainy season, and thus, experienced a higher level of ant-mediated indirect defence. Our results show that an increased plant investment in an indirect defence trait can improve the resulting defensive service against both herbivores and exploiters. EFN secretion by obligate ant-plants represents a defensive trait for which the level of investment correlates positively with the beneficial effects obtained

Reversal of hepatorenal syndrome type 1 with terlipressin plus albumin vs. placebo plus albumin in a pooled analysis of the OT-0401 and REVERSE randomised clinical studies

Background The goal of hepatorenal syndrome type 1 (HRS-1) treatment is to improve renal function. Terlipressin, a synthetic vasopressin analogue, is a systemic vasoconstrictor used for the treatment of HRS-1, where it is available. Aim To compare the efficacy of terlipressin plus albumin vs. placebo plus albumin in patients with HRS-1. Methods Pooled patient-level data from two large phase 3, randomised, placebo-controlled studies were analysed for HRS reversal [serum creatinine (SCr) value ≤133 μmol/L], 90-day survival, need for renal replacement therapy and predictors of HRS reversal. Patients received intravenous terlipressin 1–2 mg every 6 hours plus albumin or placebo plus albumin up to 14 days. Results The pooled analysis comprised 308 patients (terlipressin: n = 153; placebo: n = 155). HRS reversal was significantly more frequent with terlipressin vs. placebo (27% vs. 14%; P = 0.004). Terlipressin was associated with a more significant improvement in renal function from baseline until end of treatment, with a mean between-group difference in SCr concentration of −53.0 μmol/L (P \u3c 0.0001). Lower SCr, lower mean arterial pressure and lower total bilirubin and absence of known precipitating factors for HRS were independent predictors of HRS reversal and longer survival in terlipressin-treated patients. Conclusions Terlipressin plus albumin resulted in a significantly higher rate of HRS reversal vs. albumin alone in patients with HRS-1. Terlipressin treatment is associated with improved renal function

Nitrogen and Phosphorus Losses in Runoff on Beef Production Systems

In West Europe countries between 37 and 82% of the nitrogen (N) and between 27 and 38% of the phosphorus (P) reaching water sources come from agriculture and a strong correlation between the number of animals per area unit and N and P contribution to waters has been shown (Issermann, 1990). There are few data about the environmental impact of beef production systems in Southern Chile. The objective of this experiment was to quantify N and P losses in runoff (surface and subsurface) with two different stocking rates in Southern Chile

VZV-associated acute retinal necrosis in a patient with MS treated with natalizumab

Natalizumab (NTZ) was the first approved humanized monoclonal antibody in highly active relapsing remitting MS (RRMS). Because of the mechanism of inhibiting the migration of immune cells through the blood-brain barrier into the CNS, NTZ is associated with an increased risk of progressive multifocal leukoencephalopathy (PML) by the John Cunningham virus (JCV). Infections with other neurotropic viruses are rarely reported. We present a case of rapid retinal necrosis induced by varicella zoster virus (VZV) in a patient with RRMS under long-term NTZ treatment