280 research outputs found
UBVRI photopolarimetry of the long period eclipsing AM Herculis binary V1309
We report simultaneous UBVRI photo-polarimetric observations of the long
period (7.98 h) AM Her binary V1309 Ori. The length and shape of the eclipse
ingress and egress varies from night to night. We suggest this is due to the
variation in the brightness of the accretion stream. By comparing the phases of
circular polarization zero-crossovers with previous observations, we confirm
that V1309 Ori is well synchronized, and find an upper limit of 0.002 percent
for the difference between the spin and orbital periods. We model the
polarimetry data using a model consisting of two cyclotron emission regions at
almost diametrically opposite locations, and centered at colatitude 35 (deg)
and 145 (deg) on the surface of the white dwarf. We also present archive X-ray
observations which show that the negatively polarised accretion region is X-ray
bright.Comment: 11 pages, 12 figures (2 colour), Fig1 and Fig 4 are in lower
resolution than in original paper, accepted for publication in Monthly
Notices of the Royal Astronomical Societ
Polarimetry of an Intermediate-age Open Cluster: NGC 5617
We present polarimetric observations in the UBVRI bands of 72 stars located
in the direction of the medium age open cluster NGC 5617. Our intention is to
use polarimetry as a tool membership identification, by building on previous
investigations intended mainly to determine the cluster's general
characteristics rather than provide membership suitable for studies such as
stellar content and metallicity, as well as study the characteristics of the
dust lying between the Sun and the cluster. The obsevations were carried out
using the five-channel photopolarimeter of the Torino Astronomical Observatory
attached to the 2.15m telescope at the Complejo Astron\'omico El Leoncito
(CASLEO; Argentina. We are able to add 32 stars to the list of members of NGC
5617, and review the situation for others listed in the literature. In
particular, we find that five blue straggler stars in the region of the cluster
are located behind the same dust as the member stars are and we confirm the
membership of two red giants. The proposed polarimetric memberships are
compared with those derived by photometric and kinematical methods, with
excellent results. Among the observed stars, we identify 10 with intrinsic
polarization in their light. NGC 5617 can be polarimetrically characterized
with and . The spread in polarization
values for the stars observed in the direction of the cluster seems to be
caused by the uneven distribution of dust in front of the cluster's face.
Finally, we find that in the direction of the cluster, the interstellar medium
is apparently free of dust, from the Sun's position up to the
Carina-Sagittarius arm, where NGC 5617 seems to be located at its farthest
border
Three cases of mcr-1-positive colistin-resistant Escherichia coli bloodstream infections in Italy, August 2016 to January 2017
We describe three cases of bloodstream infection caused by colistin-resistant Escherichia coli in patients in a tertiary hospital in Italy, between August 2016 and January 2017. Whole genome sequencing detected the mcr-1 gene in three isolated strains belonging to different sequence types (STs). This occurrence of three cases with mcr-1-positive E. coli belonging to different STs in six months suggests a widespread problem in settings where high multidrug resistance is endemic such as in Italy
Multiband optical polarimetry of the BL Lac object PKS 2155--304. Intranight and long term variability
The polarized and total flux of the BL Lac object PKS 2155-304 were monitored
intensively and simultaneously in the optical UBVRI bands with the Turin
photopolarimeter at the CASLEO 2.15 m telescope during 4 campaigns in June,
August, November 1998 and August 1999. The effective observation time amounted
to ~47 hours. PKS 2155-304 showed a linear polarization percentage (P) usually
ranging between 3% and 7% and a polarization position angle (PA) mainly between
70 and 120 deg. The highest temporal resolution of our observations, 15
minutes, is unprecedented for polarimetric monitoring of this source, and has
allowed us to detect amplitude variations of the linear polarization percentage
from 6 to 7.5% in time scales of hours. In some nights the polarization
percentage seems to increase toward shorter wavelengths, however the polarized
spectrum does not vary significantly with time. The most remarkable variability
event occurred on 1998 June 18, when the degree of linear polarization
decreased by more than a factor 2 in one day in all bands, while the PA rotated
by 90 deg. This is consistent with the presence of two emission components, of
different polarization degree and position angle. Intranight variability of P
and PA can be interpreted with small amplitude physical or geometrical changes
within the jet. Measurements of the circular polarization over time intervals
of days set upper limits of 0.2%. Simultaneous photometry taken with the Turin
Photopolarimeter and with a CCD camera at Cordoba Astronomical Observatory did
not show light variations correlated with those of the linearly polarized flux.Comment: 21 pages, 6 eps figures. Accepted for The Astrophysical Journal
Supplement Serie
Multiple Klebsiella pneumoniae KPC Clones Contribute to an Extended Hospital Outbreak
The circulation of carbapenem-resistant Klebsiella pneumoniae (CRKP) is a significant problem worldwide. In this work we characterize the isolates and reconstruct the spread of a multi-clone epidemic event that occurred in an Intensive Care Unit in a hospital in Northern Italy. The event took place from August 2015 to May 2016 and involved 23 patients. Twelve of these patients were colonized by CRKP at the gastrointestinal level, while the other 11 were infected in various body districts. We retrospectively collected data on the inpatients and characterized a subset of the CRKP isolates using antibiotic resistance profiling and whole genome sequencing. A SNP-based phylogenetic approach was used to depict the evolutionary context of the obtained genomes, showing that 26 of the 32 isolates belong to three genome clusters, while the remaining six were classified as sporadic. The first genome cluster was composed of multi-resistant isolates of sequence type (ST) 512. Among those, two were resistant to colistin, one of which indicating the insurgence of resistance during an infection. One patient hospitalized in this period was colonized by two strains of CRKP, both carrying the blaKPC gene (variant KPC-3). The analysis of the genome contig containing the blaKPC locus indicates that the gene was not transmitted between the two isolates. The second infection cluster comprised four other genomes of ST512, while the third one (ST258) colonized 12 patients, causing five clinical infections and resulting in seven deaths. This cluster presented the highest level of antibiotic resistance, including colistin resistance in all 17 analyzed isolates. The three outbreaking clones did not present more virulence genes than the sporadic isolates and had different patterns of antibiotic resistance, however, were clearly distinct from the sporadic ones in terms of infection status, being the only ones causing overt infections
Effect of a standard schema of self-monitoring blood glucose in patients with poorly controlled, non-insulin-treated type 2 diabetes mellitus: A controlled longitudinal study
The effect of self-monitoring of blood glucose (SMBG) on glycemic control with regard to non-insulintreated Type 2 diabetes mellitus (NIT-Type 2 DM) is still a controversial topic. Against this backdrop, we sought to compare the effect of a continuous short-term SMBG schema with as-usual treatment, based on changes in oral antidiabetic treatment in patients with poorly controlled Type 2 DM. We reviewed 492 NIT-Type 2 DM record charts, selecting 27 patients, with poor glycemic control, who were thought to self-monitor their blood glucose levels (SMBG group). We then compared them with 27 patients treated with modifying drugs or diets to achieve and maintain the glycemic target (Control Group). Haemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) were evaluated at baseline, after 3 and 6 months. HbA1c values decreased after 3 and 6 months in the SMBG group (P < 0.001 on both occasions) and in the control group (P < 0.05 and P < 0.01, respectively), but without a significant difference between the two groups when compared at the same time. The FPG progressively decreased in both groups, reaching a significant difference in the SMBG group after 3 months and in the control group after 6 months, and without a significant difference between the two groups. The SMBG schema used in our study could be adopted for target groups before proceeding to the next therapeutic enhancement drug step, representing a useful tool that can help diabetic patients in raising awareness of and treating their disease
Pten loss promotes MAPK pathway dependency in HER2/neu breast carcinomas
Loss of the tumor suppressor gene PTEN is implicated in breast cancer progression and resistance to targeted therapies, and is thought to promote tumorigenesis by activating PI3K signaling. In a transgenic model of breast cancer, Pten suppression using a tetracycline-regulatable short hairpin (sh)RNA cooperates with human epidermal growth factor receptor 2 (HER2/neu), leading to aggressive and metastatic disease with elevated signaling through PI3K and, surprisingly, the mitogen-activated protein kinase (MAPK) pathway. Restoring Pten function is sufficient to down-regulate both PI3K and MAPK signaling and triggers dramatic tumor regression. Pharmacologic inhibition of MAPK signaling produces similar effects to Pten restoration, suggesting that the MAPK pathway contributes to the maintenance of advanced breast cancers harboring Pten loss
Asteroid taxonomic signatures from photometric phase curves
We explore the correlation between an asteroid's taxonomy and photometric
phase curve using the H, G12 photometric phase function, with the shape of the
phase function described by the single parameter G12. We explore the usability
of G12 in taxonomic classification for individual objects, asteroid families,
and dynamical groups. We conclude that the mean values of G12 for the
considered taxonomic complexes are statistically different, and also discuss
the overall shape of the G12 distribution for each taxonomic complex. Based on
the values of G12 for about half a million asteroids, we compute the
probabilities of C, S, and X complex membership for each asteroid. For an
individual asteroid, these probabilities are rather evenly distributed over all
of the complexes, thus preventing meaningful classification. We then present
and discuss the G12 distributions for asteroid families, and predict the
taxonomic complex preponderance for asteroid families given the distribution of
G12 in each family. For certain asteroid families, the probabilistic prediction
of taxonomic complex preponderance can clearly be made. The Nysa-Polana family
shows two distinct regions in the proper element space with different G12
values dominating in each region. We conclude that the G12-based probabilistic
distribution of taxonomic complexes through the main belt agrees with the
general view of C complex asteroid proportion increasing towards the outer
belt. We conclude that the G12 photometric parameter cannot be used in
determining taxonomic complex for individual asteroids, but it can be utilized
in the statistical treatment of asteroid families and different regions of the
main asteroid belt.Comment: submitted to Icaru
Multiband optical polarimetry of BL Lac objects with the Nordic Optical Telescope
Optical polarization of seven selected BL Lac objects in UBVRI bands was
studied with the Nordic Optical Telescope from December 10-14, 1999. Two of
them, 3C 66A and PKS 0735+178, were monitored for 4 nights for a total
integration time of 4.75 and 5.5 hours, respectively. Other objects (1Jy
0138-097, H 0414+009, PKS 0823-223, OJ287 and BL Lac) were observed sparsely
during the run. Apart from PKS 0823-223 (more polarized than observed in the
past), the sources show levels of flux and polarization consistent with results
at previous epochs. 3C 66A and PKS 0735+178 were intensively observed during
December 11 and 12 and exhibited variability of polarization, both on
internight and intranight time scales. Wavelength dependence of polarization
has been investigated, as well as circular polarization. The results are
discussed within the standard model for BL Lacs.Comment: 11 pages, 7 figures, accepted to Astronomy & Astrophysic
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