5,630 research outputs found
A Free-Form Lensing Grid Solution for A1689 with New Mutiple Images
Hubble Space Telescope imaging of the galaxy cluster Abell 1689 has revealed
an exceptional number of strongly lensed multiply-imaged galaxies, including
high-redshift candidates. Previous studies have used this data to obtain the
most detailed dark matter reconstructions of any galaxy cluster to date,
resolving substructures ~25 kpc across. We examine Abell 1689 (hereafter,
A1689) non-parametrically, combining strongly lensed images and weak
distortions from wider field Subaru imaging, and we incorporate member galaxies
to improve the lens solution. Strongly lensed galaxies are often locally
affected by member galaxies, however, these perturbations cannot be recovered
in grid based reconstructions because the lensing information is too sparse to
resolve member galaxies. By adding luminosity-scaled member galaxy deflections
to our smooth grid we can derive meaningful solutions with sufficient accuracy
to permit the identification of our own strongly lensed images, so our model
becomes self consistent. We identify 11 new multiply lensed system candidates
and clarify previously ambiguous cases, in the deepest optical and NIR data to
date from Hubble and Subaru. Our improved spatial resolution brings up new
features not seen when the weak and strong lensing effects are used separately,
including clumps and filamentary dark matter around the main halo. Our
treatment means we can obtain an objective mass ratio between the cluster and
galaxy components, for examining the extent of tidal stripping of the luminous
member galaxies. We find a typical mass-to-light ratios of M/L_B = 21 inside
the r<1 arcminute region that drops to M/L_B = 17 inside the r<40 arcsecond
region. Our model independence means we can objectively evaluate the
competitiveness of stacking cluster lenses for defining the geometric
lensing-distance-redshift relation in a model independent way.Comment: 23 pages with 25 figures Replced with MNRAS submitted version. Some
figures have been corrected and minor text edit
M22: A [Fe/H] Abundance Range Revealed
Intermediate resolution spectra at the Ca II triplet have been obtained for
55 candidate red giants in the field of the globular cluster M22 with the
VLT/FORS instrument. Spectra were also obtained for a number of red giants in
standard globular clusters to provide a calibration of the observed line
strengths with overall abundance [Fe/H]. For the 41 M22 member stars that lie
within the V-V_HB bounds of the calibration, we find an abundance distribution
that is substantially broader than that expected from the observed errors
alone. We argue that this broad distribution cannot be the result of
differential reddening. Instead we conclude that, as has long been suspected,
M22 is similar to omega Cen in having an intrinsic dispersion in heavy element
abundance. The observed M22 abundance distribution rises sharply to a peak at
[Fe/H] = -1.9 with a broad tail to higher abundances: the highest abundance
star in our sample has [Fe/H] = -1.45 dex. If the unusual properties of omega
Cen have their origin in a scenario in which the cluster is the remnant nucleus
of a disrupted dwarf galaxy, then such a scenario likely applies also to M22.Comment: 29 pages, 9 figures, accepted for publication in the Astrophysical
Journa
Involvement of large rearrangements in MSH6 and PMS2 genes in southern Italian patients with Lynch syndrome
Background and aim of the work: The Lynch Syndrome (LS) is associated with germline mutations in one of the MisMatch Repair (MMR) genes. Most of germline mutations are point variants, followed by large rearrangements that account to 15-55% of all pathogenic mutations. Many study reporting the frequency of large rearrangements in the MLH1 and MSH2 genes were performed, while, little is known about the contribution of large rearrangements in other MMR genes, as PMS2 and MSH6. Therefore, in this study we investigated the involvment of large rearrangements in MSH6 and PMS2 genes in a well-characterized series of 20 LS southern Italian patients. Methods: These large rearrangements are not usually detected by methods of mutation analysis, such as denaturing high-performance liquid chromatography (DHPLC) and direct DNA sequencing, but they are detectable by a known technique as the Multiplex Ligation-Probe Dependent Amplification (MLPA) assay. Results: No large rearrangements were identified in MSH6 gene; instead, a large rearrangement was identified in PMS2 gene. A large duplication including the exons 3 and 4 of the PMS2 gene was identified in a patient who developed a rectum carcinoma at 45 years of age, an endometrial carcinoma and a vaginal cancer at the 65 years of age. Conclusion: We can affirm that the detection of large rearrangements in the MSH6 and PMS2 genes should be included in the routine testing for Lynch syndrome, especially considering the simplicity of the MLPA assay
Triple positive breast cancer. A distinct subtype?
Breast cancer is a heterogeneous disease, and within the HER-2 positive subtype this is highly exemplified by the presence of substantial phenotypical and clinical heterogeneity, mostly related to hormonal receptor (HR) expression. It is well known how HER-2 positivity is commonly associated with a more aggressive tumor phenotype and decreased overall survival and, moreover, with a reduced benefit from endocrine treatment. Preclinical studies corroborate the role played by functional crosstalks between HER-2 and estrogen receptor (ER) signaling in endocrine resistance and, more recently, the activation of ER signaling is emerging as a possible mechanism of resistance to HER-2 blocking agents. Indeed, HER-2 positive breast cancer heterogeneity has been suggested to underlie the variability of response not only to endocrine treatments, but also to HER-2 blocking agents. Among HER-2 positive tumors, HR status probably defines two distinct subtypes, with dissimilar clinical behavior and different sensitivity to anticancer agents. The triple positive subtype, namely, ER/PgR/Her-2 positive tumors, could be considered the subset which most closely resembles the HER-2 negative/HR positive tumors, with substantial differences in biology and clinical outcome. We argue on whether in this subgroup the "standard" treatment may be considered, in selected cases, i.e., small tumors, low tumor burden, high expression of both hormonal receptors, an overtreatment. This article review the existing literature on biologic and clinical data concerning the HER-2/ER/PgR positive tumors, in an attempt to better define the HER-2 subtypes and to optimize the use of HER-2 targeted agents, chemotherapy and endocrine treatments in the various subsets
Imatinib mesylate therapy in chronic myeloid leukemia patients in stable complete cytogenetic response after interferon-alpha results in any high complete molecular response.
To determine the impact on minimal residual disease by switching to imatinib chronic phase chronic myeloid leukaemia (CP-CML) patients responsive to interferon-alpha (IFNα), in stable complete cytogenetic response (CCR) but with persistent PCR positivity.
Twenty-six Philadelphia positive (Ph+) CML patients in stable CCR after IFNα but persistently positive at PCR analysis during this treatment, were given imatinib mesylate at standard dose.
At enrolment into the study, median IFN treatment and CCR duration were 88 months (range 15–202) and 73 months (range 10–148), respectively. Imatinib treatment resulted in a progressive and consistent decline of the residual disease as measured by quantitative PCR (RQ-PCR) in all but one of the 26 patients; at the end of follow-up, after a median of 32 months (range 21–49) of treatment, a major molecular response (BCR/ABL levels <0.1) was reached in 20 patients (77%), and BCR/ABL transcripts were undetectable in 13 (50%). The achievement of molecular response was significantly correlated with post-IFN baseline transcript level (mean 1.194 for patients achieving complete molecular response versus 18.97 for those who did not; p < 0.001), but not with other clinical/biological disease characteristics.
These results indicate that patients induced into CCR by IFN treatment represent a subset with very favourable prognosis, which can significantly improve molecular response with imatinib and further support investigative treatment schedules combining these two drugs
Expression and purification of the recombinant subunits of toluene/o-xylene monooxygenase and reconstitution of the active complex.
This paper describes the cloning of the genes coding for each component of the complex of toluene/o-xylene monooxygenase from Pseudomonas stutzeri OX1, their expression, purification and characterization. Moreover, the reconstitution of the active complex from the recombinant subunits has been obtained, and the functional role of each component in the electron transfer from the electron donor to molecular oxygen has been determined. The coexpression of subunits B, E and A leads to the formation of a subcomplex, named H, with a quaternary structure (BEA)2, endowed with hydroxylase activity. Tomo F component is an NADH oxidoreductase. The purified enzyme contains about 1 mol of FAD, 2 mol of iron, and 2 mol of acid labile sulfide per mol of protein, as expected for the presence of one [2Fe-2S] cluster, and exhibits a typical flavodoxin absorption spectrum. Interestingly, the sequence of the protein does not correspond to that previously predicted on the basis of DNA sequence. We have shown that this depends on minor errors in the gene sequence that we have corrected. C component is a Rieske-type ferredoxin, whose iron and acid labile sulfide content is in agreement with the presence of one [2Fe-2S] cluster. The cluster is very sensitive to oxygen damage. Mixtures of the subcomplex H and of the subunits F, C and D are able to oxidize p-cresol into 4-methylcathecol, thus demonstrating the full functionality of the recombinant subunits as purified. Finally, experimental evidence is reported which strongly support a model for the electron transfer. Subunit F is the first member of an electron transport chain which transfers electrons from NADH to C, which tunnels them to H subcomplex, and eventually to molecular oxyge
Inclusive search for same-sign dilepton signatures in pp collisions at root s=7 TeV with the ATLAS detector
An inclusive search is presented for new physics in events with two isolated leptons (e or mu) having the same electric charge. The data are selected from events collected from p p collisions at root s = 7 TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb(-1). The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sources of same-sign high-mass dilepton events in the ee, e mu and mu mu channels. Four models predicting same-sign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. A lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks
Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV
A measurement of the production cross-section for top quark pairs(\ttbar)
in collisions at \sqrt{s}=7 \TeV is presented using data recorded with
the ATLAS detector at the Large Hadron Collider. Events are selected in two
different topologies: single lepton (electron or muon ) with large
missing transverse energy and at least four jets, and dilepton (,
or ) with large missing transverse energy and at least two jets. In a
data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton
topology and 9 events in the dilepton topology. The corresponding expected
backgrounds from non-\ttbar Standard Model processes are estimated using
data-driven methods and determined to be events and events, respectively. The kinematic properties of the selected events are
consistent with SM \ttbar production. The inclusive top quark pair production
cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where
the first uncertainty is statistical and the second systematic. The measurement
agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables,
CERN-PH number and final journal adde
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