5,526 research outputs found

    X-ray Bright Optically Inactive Galaxies (XBONG) in XMM-Newton/SDSS fields: more diluted than absorbed?

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    We explore the properties of X-ray Bright Optically Inactive Galaxies (XBONG) detected in the 0.5-8 keV spectral band in 20 public XMM fields overlapping with the SDSS. We constrain our sample to optically extended systems with log (f_X/f_o > -2) that have spectroscopic identifications available from the SDSS (r<19.2 mag). The resulting sample contains 12 objects with L_X (0.5-8keV)= 5 x 10^41 - 2x10^44 erg s-1 in the redshift range 0.06 < z < 0.45. The X-ray emission in four cases is extended suggesting the presence of hot gas associated with a cluster or group of galaxies. The X-ray spectral fits show that two additional sources are best fit with a thermal component emission (kT \~ 1 keV). Three sources aremost likely associated with AGN: their X-ray spectrum is described by a steep photon index ~ 1.9 typical of unobscured AGN while, they are very luminous in X-rays (L_X (0.5-8 keV) ~ 10^43 - 10^44 erg s-1.) Finally, three more sources could be associated with either normal galaxies or unobscured Low Luminosity AGN (L_X < 10^42 erg s-1). We find no evidence for significant X-ray absorbing columns in any of our XBONGs. The above suggest that XBONGs, selected in the total 0.5-8 keV band, comprise a mixed bag of objects primarily including normal elliptical galaxies and type-1 AGN whose optical nuclear spectrum is probably diluted by the strong stellar continuum. Nevertheless, as our sample is not statistically complete we cannot exclude the possibility that a fraction of optically fainter XBONG may be associated with heavily obscured AGN.Comment: 8 pages to appear in MNRA

    Assessment of the 2020 NICE criteria for preoperative radiotherapy in patients with rectal cancer treated by surgery alone in comparison with proven MRI prognostic factors: a retrospective cohort study

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    BACKGROUND: Selection of patients for preoperative treatment in rectal cancer is controversial. The new 2020 National Institute for Health and Care Excellence (NICE) guidelines, consistent with the National Comprehensive Cancer Network guidelines, recommend preoperative radiotherapy for all patients except for those with radiologically staged T1-T2, N0 tumours. We aimed to assess outcomes in non-irradiated patients with rectal cancer and to stratify results on the basis of NICE criteria, compared with known MRI prognostic factors now omitted by NICE. METHODS: For this retrospective cohort study, we identified patients undergoing primary resectional surgery for rectal cancer, without preoperative radiotherapy, at Basingstoke Hospital (Basingstoke, UK) between Jan 1, 2011, and Dec 31, 2016, and at St Marks Hospital (London, UK) between Jan 1, 2007, and Dec 31, 2017. Patients with MRI-detected extramural venous invasion, MRI-detected tumour deposits, and MRI-detected circumferential resection margin involvement were categorised as MRI high-risk for recurrence (local or distant), and their outcomes (disease-free survival, overall survival, and recurrence) were compared with patients defined as high-risk according to NICE criteria (MRI-detected T3+ or MRI-detected N+ status). Kaplan-Meier and Cox proportional hazards analyses were used to compare the groups. FINDINGS: 378 patients were evaluated, with a median of 66 months (IQR 44-95) of follow up. 22 (6%) of 378 patients had local recurrence and 68 (18%) of 378 patients had distant recurrence. 248 (66%) of 378 were classified as high-risk according to NICE criteria, compared with 121 (32%) of 378 according to MRI criteria. On Kaplan-Meier analysis, NICE high-risk patients had poorer 5-year disease-free survival compared with NICE low-risk patients (76% [95% CI 70-81] vs 87% [80-92]; hazard ratio [HR] 1·91 [95% CI 1·20-3·03]; p=0·0051) but not 5-year overall survival (80% [74-84] vs 88% [81-92]; 1·55 [0·94-2·53]; p=0·077). MRI criteria separated patients into high-risk versus low-risk groups that predicted 5-year disease-free survival (66% [95% CI 57-74] vs 88% [83-91]; HR 3·01 [95% CI 2·02-4·47]; p<0·0001) and 5-year overall survival (71% [62-78] vs 89% [84-92]; 2·59 [1·62-3·88]; p<0·0001). On multivariable analysis, NICE risk assessment was not associated with either disease-free survival or overall survival, whereas MRI criteria predicted disease-free survival (HR 2·74 [95% CI 1·80-4·17]; p<0·0001) and overall survival (HR 2·44 [95% CI 1·51-3·95]; p=0·00027). 139 NICE high-risk patients who were defined as low-risk based on MRI criteria had similar disease-free survival as 118 NICE low-risk patients; therefore, 37% (139 of 378) of patients in this study cohort would have been overtreated with NICE 2020 guidelines. Of the 130 patients defined as low-risk by NICE guidelines, 12 were defined as high-risk on MRI risk stratification and would have potentially been missed for treatment. INTERPRETATION: Compared to previous guidelines, implementation of the 2020 NICE guidelines will result in significantly more patients receiving preoperative radiotherapy. High-quality MRI selects patients with good outcomes (particularly low local recurrence) without radiotherapy, with little margin for improvement. Overuse of radiotherapy could occur with this unselective approach. The high-risk group, with the most chance of benefiting from preoperative radiotherapy, is not well selected on the basis of NICE 2020 criteria and is better identified with proven MRI prognostic factors (extramural venous invasion, tumour deposits, and circumferential resection margin). FUNDING: None

    Composite Fermion Wavefunctions Derived by Conformal Field Theory

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    The Jain theory of hierarchical Hall states is reconsidered in the light of recent analyses that have found exact relations between projected Jain wavefunctions and conformal field theory correlators. We show that the underlying conformal theory is precisely given by the W-infinity minimal models introduced earlier. This theory involves a reduction of the multicomponent Abelian theory that is similar to the projection to the lowest Landau level in the Jain approach. The projection yields quasihole excitations obeying non-Abelian fractional statistics. The analysis closely parallels the bosonic conformal theory description of the Pfaffian and Read-Rezayi states.Comment: 4 pages, 1 figur

    Resolving the extragalactic hard X-ray background

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    The origin of the hard (2-10 keV) X-ray background has remained mysterious for over 35 years. Most of the soft (0.5-2 keV) X-ray background has been resolved into discrete sources, which are primarily quasars; however, these sources do not have the flat spectral shape required to match the X-ray background spectrum. Here we report the results of an X-ray survey 30 times more sensitive than previous studies in the hard band and four times more sensitive in the soft band. The sources detected in our survey account for at least 75 per cent of the hard X-ray background. The mean X-ray spectrum of these sources is in good agreement with that of the background. The X-ray emission from the majority of the detected sources is unambiguously associated with either the nuclei of otherwise normal bright galaxies or optically faint sources, which could either be active nuclei of dust enshrouded galaxies or the first quasars at very high redshifts.Comment: Nature article in pres

    Germ Line Mutations in the Thyroid Hormone Receptor Alpha Gene Predispose to Cutaneous Tags and Melanocytic Nevi

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    Background: Many physiological effects of thyroid hormone (TH) are mediated by its canonical action via nuclear receptors (TH receptor α and β [TRα and TRβ]) to regulate transcription of target genes. Heterozygous dominant negative mutations in human TRα mediate resistance to thyroid hormone alpha (RTHα), characterized by features of hypothyroidism (e.g., skeletal dysplasia, neurodevelopmental retardation, constipation) in specific tissues, but near-normal circulating TH concentrations. Hitherto, 41 RTHα cases have been recorded worldwide. Methods: RTHα cases (n = 10) attending a single center underwent cutaneous assessment, recording skin lesions. Lesions excised from different RTHα patients were analyzed histologically and profiled for cellular markers of proliferation and oncogenic potential. Proliferative characteristics of dermal fibroblasts and inducible pluripotent stem cell (iPSC)-derived keratinocytes from patients and control subjects were analyzed. Results: Multiple skin tags and nevi were recorded in all cases, mainly in the head and neck area with a predilection for flexures. The affected patients had highly deleterious mutations (p.E403X, p.E403K, p.F397fs406X, p.A382PfsX7) involving TRα1 alone or mild/moderate loss-of-function mutations (p.A263V, p.L274P) common to TRα1 and TRα2 isoforms. In four patients, although lesions excised for cosmetic reasons were benign intradermal melanocytic nevi histologically, they significantly overexpressed markers of cell proliferation (K17, cyclin D1) and type 3 deiodinase. In addition, oncogenic markers typical of basal cell carcinoma (Gli-1, Gli-2, Ptch-1, n = 2 cases) and melanoma (c-kit, MAGE, CDK4, n = 1) were markedly upregulated in skin lesions. Cell cycle progression and proliferation of TRα mutation-containing dermal fibroblasts and iPSC-derived keratinocytes from patients were markedly increased. Conclusions: Our observations highlight frequent occurrence of skin tags and benign melanocytic nevi in RTHα, with cutaneous cells from patients being in a hyperproliferative state. Such excess of skin lesions, including nevi expressing oncogenic markers, indicates that dermatologic surveillance of RTHα patients, monitoring lesions for features that are suspicious for neoplastic change, is warranted

    A genealogical map of the concept of habit

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    The notion of information processing has dominated the study of the mind for over six decades. However, before the advent of cognitivism, one of the most prominent theoretical ideas was that of Habit. This is a concept with a rich and complex history, which is again starting to awaken interest, following recent embodied, enactive critiques of computationalist frameworks. We offer here a very brief history of the concept of habit in the form of a genealogical network-map. This serves to provide an overview of the richness of this notion and as a guide for further re-appraisal. We identify 77 thinkers and their influences, and group them into seven schools of thought. Two major trends can be distinguished. One is the associationist trend, starting with the work of Locke and Hume, developed by Hartley, Bain, and Mill to be later absorbed into behaviorism through pioneering animal psychologists (Morgan and Thorndike). This tradition conceived of habits atomistically and as automatisms (a conception later debunked by cognitivism). Another historical trend we have called organicism inherits the legacy of Aristotle and develops along German idealism, French spiritualism, pragmatism, and phenomenology. It feeds into the work of continental psychologists in the early 20th century, influencing important figures such as Merleau-Ponty, Piaget, and Gibson. But it has not yet been taken up by mainstream cognitive neuroscience and psychology. Habits, in this tradition, are seen as ecological, self-organizing structures that relate to a web of predispositions and plastic dependencies both in the agent and in the environment. In addition, they are not conceptualized in opposition to rational, volitional processes, but as transversing a continuum from reflective to embodied intentionality. These are properties that make habit a particularly attractive idea for embodied, enactive perspectives, which can now re-evaluate it in light of dynamical systems theory and complexity research.This work is funded by the eSMCs: Extending Sensorimotor Contingencies to Cognition project, FP7-ICT-2009-6 no: 270212. XEB hold a Postdoc with the FECYT foundation (funded by Programa Nacional de Movilidad de Recursos Humanos del MEC-MICINN, Plan I-D+I 2008-2011, Spain) during the development of this work and acknowledges IAS-Research group funding IT590-13 from the Basque Government

    Human Subcutaneous Adipose Tissue Sampling using a Mini-liposuction Technique

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    Studies on adipose tissue are useful in understanding metabolic and other conditions. Human subcutaneous adipose tissue is accessible. With appropriate training and strict adherence to aseptic technique, subcutaneous adipose samples can be safely and efficiently obtained in a non-clinical setting by researchers. Following the administration of local anesthetic lateral to the umbilicus, a 14 G needle attached to a 5 or 10 mL syringe is inserted through the skin into the subcutaneous tissue. Under suction, the syringe is moved in a reciprocating, slicing motion to isolate fragments of adipose tissue. Withdrawing the plunger is enough to ensure that adipose tissue fragments are aspirated through the needle into the syringe. A single biopsy can collect about 200 mg of tissue. This biopsy technique is very safe for both participants and research staff. Following the biopsy, participants can resume most everyday activities, although they should avoid swimming and overly strenuous activities for 48 h to avoid excessive bleeding. Participants can safely undergo 2 biopsies within a single day, meaning that the technique can be applied in before-after acute intervention studies

    Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research

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    This review discusses the current status of supermassive black hole research, as seen from a purely observational standpoint. Since the early '90s, rapid technological advances, most notably the launch of the Hubble Space Telescope, the commissioning of the VLBA and improvements in near-infrared speckle imaging techniques, have not only given us incontrovertible proof of the existence of supermassive black holes, but have unveiled fundamental connections between the mass of the central singularity and the global properties of the host galaxy. It is thanks to these observations that we are now, for the first time, in a position to understand the origin, evolution and cosmic relevance of these fascinating objects.Comment: Invited Review, 114 pages. Because of space requirements, this version contains low resolution figures. The full resolution version can be downloaded from http://www.physics.rutgers.edu/~lff/publications.htm

    Differential branching fraction and angular analysis of the decay B0→K∗0μ+μ−

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    The angular distribution and differential branching fraction of the decay B 0→ K ∗0 μ + μ − are studied using a data sample, collected by the LHCb experiment in pp collisions at s√=7 TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
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