An updated stellar census of the Quintuplet cluster

Context. Found within the central molecular zone, the Quintuplet is one of the most massive young clusters in the Galaxy. As a consequence it offers the prospect of constraining stellar formation and evolution in extreme environments. However, current observations suggest that it comprises a remarkably diverse stellar population that is difficult to reconcile with an instantaneous formation event. Aims. To better understand the nature of the cluster our aim is to improve observational constraints on the constituent stars. Methods. In order to accomplish this goal we present Hubble Space Telescope/NICMOS+WFC3 photometry and Very Large Telescope/SINFONI+KMOS spectroscopy for ∼100 and 71 cluster members, respectively. Results. Spectroscopy of the cluster members reveals the Quintuplet to be far more homogeneous than previously expected. All supergiants are classified as either O7–8 Ia or O9–B0 Ia, with only one object of earlier (O5 I–III) spectral type. These stars form a smooth morphological sequence with a cohort of seven early-B hypergiants and six luminous blue variables and WN9-11h stars, which comprise the richest population of such stars of any stellar aggregate known. In parallel, we identify a smaller population of late-O hypergiants and spectroscopically similar WN8–9ha stars. No further H-free Wolf–Rayet (WR) stars are identified, leaving an unexpectedly extreme ratio of 13:1 for WC/WN stars. A subset of the O9–B0 supergiants are unexpectedly faint, suggesting they are both less massive and older than the greater cluster population. Finally, no main sequence objects were identifiable. Conclusions. Due to uncertainties over which extinction law to apply, it was not possible to quantitatively determine a cluster age via isochrone fitting. Nevertheless, we find an impressive coincidence between the properties of cluster members preceding the H-free WR phase and the evolutionary predictions for a single, non-rotating 60 M⊙ star; in turn this implies an age of ∼3.0–3.6 Myr for the Quintuplet. Neither the late O-hypergiants nor the low luminosity supergiants are predicted by such a path; we suggest that the former either result from rapid rotators or are the products of binary driven mass-stripping, while the latter may be interlopers. The H-free WRs must evolve from stars with an initial mass in excess of 60 M⊙ but it appears difficult to reconcile their observational properties with theoretical expectations. This is important since one would expect the most massive stars within the Quintuplet to be undergoing core-collapse/SNe at this time; since the WRs represent an evolutionary phase directly preceding this event,their physical properties are crucial to understanding both this process and the nature of the resultant relativistic remnant. As such, the Quintuplet provides unique observational constraints on the evolution and death of the most massive stars forming in the local, high metallicity Universe

The Arches cluster revisited: II. A massive eclipsing spectroscopic binary in the Arches cluster

We have carried out a spectroscopic variability survey of some of the most massive stars in the Arches cluster, using K-band observations obtained with SINFONI on the VLT. One target, F2, exhibits substantial changes in radial velocity; in combination with new KMOS and archival SINFONI spectra, its primary component is found to undergo radial velocity variation with a period of 10.483+/-0.002 d and an amplitude of ~350 km/s-1. A secondary radial velocity curve is also marginally detectable. We reanalyse archival NAOS-CONICA photometric survey data in combination with our radial velocity results to confirm this object as an eclipsing SB2 system, and the first binary identified in the Arches. We model it as consisting of an 82+/-12 M⊙ WN8-9h primary and a 60+/-8 M⊙ O5-6 Ia+ secondary, and as having a slightly eccentric orbit, implying an evolutionary stage prior to strong binary interaction. As one of four X-ray bright Arches sources previously proposed as colliding-wind massive binaries, it may be only the first of several binaries to be discovered in this cluster, presenting potential challenges to recent models for the Arches' age and composition. It also appears to be one of the most massive binaries detected to date; the primary's calculated initial mass of >~120 M⊙ would arguably make this the most massive binary known in the Galaxy

Decision and function problems based on boson sampling

Boson sampling is a mathematical problem that is strongly believed to be intractable for classical computers, whereas passive linear interferometers can produce samples efficiently. So far, the problem remains a computational curiosity, and the possible usefulness of boson-sampling devices is mainly limited to the proof of quantum supremacy. The purpose of this work is to investigate whether boson sampling can be used as a resource of decision and function problems that are computationally hard, and may thus have cryptographic applications. After the definition of a rather general theoretical framework for the design of such problems, we discuss their solution by means of a brute-force numerical approach, as well as by means of non-boson samplers. Moreover, we estimate the sample sizes required for their solution by passive linear interferometers, and it is shown that they are independent of the size of the Hilbert space.Comment: Close to the version published in PR

Local Food Systems: Concepts, Impacts, and Issues

This comprehensive overview of local food systems explores alternative definitions of local food, estimates market size and reach, describes the characteristics of local consumers and producers, and examines early indications of the economic and health impacts of local food systems. There is no consensus on a definition of “local” or “local food systems” in terms of the geographic distance between production and consumption. But defining “local” based on marketing arrangements, such as farmers selling directly to consumers at regional farmers’ markets or to schools, is well recognized. Statistics suggest that local food markets account for a small, but growing, share of U.S. agricultural production. For smaller farms, direct marketing to consumers accounts for a higher percentage of their sales than for larger farms. Findings are mixed on the impact of local food systems on local economic development and better nutrition levels among consumers, and sparse literature is so far inconclusive about whether localization reduces energy use or greenhouse gas emissions.local food systems, farmers’ markets, direct-to-consumer marketing, direct-to-retail/ foodservice marketing, community supported agriculture, farm to school programs, Farmers’ Market Promotion Program, food miles, Community/Rural/Urban Development,

Electron photodetachment from a Dirac bubble potential. A model for the fullerene negative ion C-60

A model for the fullerene anion C-60 is proposed in which the outer electron moves in an attractive deltafunction potential in the shape of a spherical bubble. Exact solutions from this "Dirac bubble potential" were previously worked out. On the basis of this model, the photodetachment cross-section and its angular distribution are computed as functions of photoelectron energy, for the electron in both S-like and P-like bound states. Secondary maxima and minima in the cross section appear at higher energy values, somewhat analogous to the scattering of radiation from a conducting sphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29792/1/0000134.pd

Outcome of probe-based confocal laser endomicroscopy (pCLE) during endoscopic retrograde cholangiopancreatography: a single-center prospective study in 45 patients

Background: Diagnosis of pre-malignant and malignant lesions in the bile duct and the pancreas is sometimes cumbersome. This applies in particular to intraductal papillary mucinous neoplasia (IPMN) and bile duct strictures in primary sclerosing cholangitis (PSC). Aims: To evaluate in a prospective cohort study the sensitivity and specificity of probe-based confocal laser microscopy (pCLE) during endoscopic retrograde cholangiopancreatography (ERCP). Methods: We performed pCLE together with mother-baby endoscopy (SpyGlass) during 50 ERCP sessions in 45 patients. The Miami and Paris criteria were applied. Clinical diagnosis via imaging was compared to pCLE and the final pathological diagnosis from surgically-resected, biopsy, or cytology specimens. Patients were followed up for at least 1 year. Results: We were able to perform pCLE in all patients. Prior to endoscopy, the diagnosis was benign in 23 patients and undetermined (suspicious) in 16 patients, while six patients had an unequivocal diagnosis of malignancy. Sensitivity was 91% and specificity 52%. The positive (PPV) and negative predictive value (NPV) was 82% and 100%, respectively. Apart from mild post-ERCP pancreatitis in two patients, no complications occurred. Conclusions: Our study showed that pCLE is a safe, expert endoscopic method with high technical feasibility, high sensitivity and high NPV. It provided diagnostic information that can be helpful for decisions on patient management, especially in the case of IPMN and unclear pancreatic lesions, in individuals whom are at increased risk for pancreatic cancer

Peptide microarray-based characterization of antibody responses to host proteins after bacille Calmette-Guerin vaccination

BACKGROUND: Bacille Calmette–Guérin (BCG) is the world’s most widely distributed vaccine, used against tuberculosis (TB), in cancer immunotherapy, and in autoimmune diseases due to its immunomodulatory properties. To date, the effect of BCG vaccination on antibody responses to host proteins has not been reported. High-content peptide microarrays (HCPM) offer a unique opportunity to gauge specific humoral immune responses. METHODS: The sera of BCG-vaccinated healthy adults were tested on a human HCPM platform (4953 randomly selected epitopes of human proteins) to detect specific immunoglobulin gamma (IgG) responses. Samples were obtained at 56, 112, and 252 days after vaccination. Immunohistology was performed on lymph node tissue from patients with TB lymphadenitis. Results were analysed with a combination of existing and novel statistical methods. RESULTS: IgG recognition of host peptides exhibited a peak at day 56 post BCG vaccination in all study subjects tested, which diminished over time. Primarily, IgG responses exhibited increased reactivity to ion transporters (sodium, calcium channels), cytokine receptors (interleukin 2 receptor β (IL2Rβ), fibroblast growth factor receptor 1 (FGFR1)), other cell surface receptors (inositol, somatostatin, angiopoeitin), ribonucleoprotein, and enzymes (tyrosine kinases, phospholipase) on day 56. There was decreased IgG reactivity to transforming growth factor-beta type 1 receptor (TGFβR1) and, in agreement with the peptide microarray findings, immunohistochemical analysis of TB-infected lymph node samples revealed an overexpression of TGFβR in granulomatous lesions. Moreover, the vesicular monoamine transporter (VMAT2) showed increased reactivity on days 112 and 252, but not on day 56 post-vaccination. IgG to interleukin 4 receptor (IL4R) showed increased reactivity at 112 days post-vaccination, while IgG to IL2Rβ and FGFR1 showed decreased reactivity on days 112 and 252 as compared to day 56 post BCG vaccination. CONCLUSIONS: BCG vaccination modifies the host’s immune landscape after 56 days, but this imprint changes over time. This may influence the establishment of immunological memory in BCG-vaccinated individuals

The structures and dipole moments of Ar–PF3 and Kr–PF3

The complexes of PF3 with Ar and Kr, were studied by Fourier transform microwave spectroscopy. The force constants and amplitudes of vibration for the van der Waals modes of the complexes and the average moments of inertia and structural parameters were estimated from the centrifugal distortion constants. The distance (Rc.m. )ave between the rare‐gas atom and the center of mass of PF3 is 3.959 Å for the Ar complex and 4.077 Å for Kr while the angle (θc.m. )ave between the Rc.m. vector and the C3 axis of the PF3 is 69.30° and 67.25°, respectively. The dipole moments of both complexes and of free PF3 were determined. The induced dipole components estimated for the rare gas using electric fields from ab initio calculations of PF3 agree with the experimental values for a conformation with the rare gas over a PF2 face. The PF2 face conformation is also consistent with the observed and ab initio estimates of the 83 Kr nuclear quadrupole coupling constant for the 83 Kr–PF3 species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70747/2/JCPSA6-90-12-6949-1.pd

Advancing national greenhouse gas inventories for agriculture in developing countries : improving activity data, emission factors and software technology

Peer reviewedPublisher PD

Disease-related p63 DBD mutations impair DNA binding by distinct mechanisms and varying degree

: The transcription factor p63 shares a high sequence identity with the tumour suppressor p53 which manifests itself in high structural similarity and preference for DNA sequences. Mutations in the DNA binding domain (DBD) of p53 have been studied in great detail, enabling a general mechanism-based classification. In this study we provide a detailed investigation of all currently known mutations in the p63 DBD, which are associated with developmental syndromes, by measuring their impact on transcriptional activity, DNA binding affinity, zinc binding capacity and thermodynamic stability. Some of the mutations we have further characterized with respect to their ability to convert human dermal fibroblasts into induced keratinocytes. Here we propose a classification of the p63 DBD mutations based on the four different mechanisms of DNA binding impairment which we identified: direct DNA contact, zinc finger region, H2 region, and dimer interface mutations. The data also demonstrate that, in contrast to p53 cancer mutations, no p63 mutation induces global unfolding and subsequent aggregation of the domain. The dimer interface mutations that affect the DNA binding affinity by disturbing the interaction between the individual DBDs retain partial DNA binding capacity which correlates with a milder patient phenotype