Multi-Frequency Study of the NVSS Foreground Sources in the Cosmic Background Imager Fields

The point radio sources comprise one amongst the major contaminants of the Cosmic Microwave Background radiation. Consequently, they possess a significant potential for causing severe distortion of the information imprinted in its anisotropies. They demand therefore some sort of treatment that usually boils down to removing contaminated pixels in any CMB experiment. As a support to the Cosmic Background Imager (CBI) we have carried out intensive observations of a sample of nearly 6000 NVSS sources that happen to be in the targeted fields at two frequencies (4.85 and 10.45 GHz) with the 100-m telescope at Effelsberg. The objective has been the estimation of the flux density that each one of them could contribute at the central frequency of the CBI (31 GHz) on the basis of their three-point radio spectral index and their 1.4-GHz flux density as extracted from the NVSS catalogue. However, the compilation of such an extended data base of multi-frequency measurements gives handle for a series of further studies. First, we exploit the sample in order to compute the source counts at different frequencies. That provides the opportunity for comparison with direct surveys at those wavelengths and more importantly with the theoretical predictions. Practically, this can assist the computation of the confusion limits that set a physical limit to the reachable sensitivity of radio instruments. Further, the computed spectral indices have been used to trace candidates for GHz-Peacked Spectrum sources and their extreme sub-class of High Frequency Peakers that are believed to be the early evolutionary stages of radio activity. Additionally, although the observations have been designed to be time-efficient we manage to carry some polarization studies. Finally, the weakness of the anisotropies in terms of brightness temperature has forced the goal of reaching levels of only a few mJy. That became possible only with the deep understanding of the system and the development of new case-dependent methods and tools of analysis

Climate and Vector Borne Pathogens: Challenges of the Present and of the Future

International audienc

Physical Conditions and Variability Processes in AGN Jets through Multi-Frequency Linear and Circular Radio Polarization Monitoring

Radio polarimetry is an invaluable tool to investigate the physical conditions and variability processes in active galactic nuclei (AGN) jets. However, detecting their linear and circular polarization properties is a challenging endeavor due to their low levels and possible depolarization effects. We have developed an end-to-end data analysis methodology to recover the polarization properties of unresolved sources with high accuracy. It has been applied to recover the linear and circular polarization of 87 AGNs measured by the F-GAMMA program from July 2010 to January 2015 with a mean cadence of 1.3 months. Their linear polarization was recovered at four frequencies between 2.64 and 10.45 GHz and the circular polarization at 4.85 and 8.35 GHz. The physical conditions required to reproduce the observed polarization properties and the processes which induce their variability were investigated with a full-Stokes radiative transfer code which emulates the synchrotron emission of modeled jets. The model was used to investigate the conditions needed to reproduce the observed polarization behavior for the blazar 3C 454.3, assuming that the observed variability is attributed to evolving internal shocks propagating downstream.Comment: 6 pages, 2 figure

Radio QPO in the γ{\gamma}-ray-loud X-ray binary LS I +61∘{^\circ}303

LS I +61${^\circ}$303 is a $\gamma$-ray emitting X-ray binary with periodic radio outbursts with time scales of one month. Previous observations have revealed microflares superimposed on these large outbursts with periods ranging from a few minutes to hours. This makes LS I +61${^\circ}$303, along with Cyg X-1, the only TeV emitting X-ray binary exhibiting radio microflares. To further investigate these microflaring activity in LS I +61${^\circ}$303 we observed the source with the 100-m Effelsberg radio telescope at 4.85, 8.35, and 10.45 GHz and performed timing analysis on the obtained data. Radio oscillations of 15 hours time scales are detected at all three frequencies. We also compare the spectral index evolution of radio data to that of the photon index of GeV data observed by Fermi-LAT. We conclude that the observed QPO could result from multiple shocks in a jet.Comment: 5 pages, 4 figures, accepted for publication in MNRA

Comparison of Real-Time Quantitative PCR and Culture for the Diagnosis of Emerging Rickettsioses

Diagnosis of Rickettsia infection would benefit by use of the more rapid and sensitive method of quantitative real-time PCR than the time-intensive and less sensitive method of culturing Rickettsia species from skin biopsies. We evaluated culture sensitivity compared to PCR according to sampling delay and previous antibiotic treatment. We found that skin biopsies can be positive even when molecular tests were negative, and a negative result using molecular assays did not exclude the diagnosis of Rickettsia spp. infection. Rickettsia africae was the most common species in skin biopsies and R. slovaca was most common in ticks. We found a positive correlation between the number of bacteria copies and the isolation success in skin biopsies and ticks. The probability of isolating Rickettsia spp. was higher in untreated patients and in patients from our hometown. To increase the sensitivity of culture, skin biopsies should be sampled before treatment early in the course of the disease and should be inoculated as soon as possible

Potential for Tick-borne Bartonelloses

Although possible, tick transmission to a vertebrate host has not been proven

Vancomycin Treatment of Infective Endocarditis Is Linked with Recently Acquired Obesity

BACKGROUND: Gut microbiota play a major role in digestion and energy conversion of nutrients. Antibiotics, such as avoparcin (a vancomycin analogue), and probiotics, such as Lactobacillus species, have been used to increase weight in farm animals. We tested the effect of antibiotics given for infective endocarditis (IE) on weight gain (WG). METHODOLOGY/PRINCIPAL FINDINGS: Forty-eight adults with a definite diagnosis of bacterial IE (antibiotic group) were compared with forty-eight age-matched controls without IE. Their body mass index (BMI) was collected at one month before the first symptoms and one year after hospital discharge. The BMI increased significantly and strongly in vancomycin-plus-gentamycin-treated patients (mean [+/-SE] kg/m(2), +2.3 [0.9], p = 0.03), but not in controls or in patients treated with other antibiotics. Seventeen patients had a BMI increase of >or=10%, and five of the antibiotic group developed obesity. The treatment by vancomycin-plus-gentamycin was an independent predictor of BMI increase of >or=10% (adjusted OR, 6.7; 95% CI, 1.37-33.0; p = 0.02), but not treatment with other antibiotics. Weight gain was particularly high in male patients older than 65 who did not undergo cardiac surgery. Indeed, all three vancomycin-treated patients with these characteristics developed obesity. CONCLUSIONS/SIGNIFICANCE: A major and significant weight gain can occur after a six-week intravenous treatment by vancomycin plus gentamycin for IE with a risk of obesity, especially in males older than 65 who have not undergone surgery. We speculate on the role of the gut colonization by Lactobacillus sp, a microorganism intrinsically resistant to vancomycin, used as a growth promoter in animals, and found at a high concentration in the feces of obese patients. Thus, nutritional programs and weight follow-up should be utilized in patients under such treatment