93 research outputs found

    Starburst or AGN Dominance in Submillimetre-Luminous Candidate AGN?

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    It is widely believed that ultraluminous infrared (IR) galaxies and active galactic nuclei (AGN) activity are triggered by galaxy interactions and merging, with the peak of activity occurring at z~2, where submillimetre galaxies are thousands of times more numerous than local ULIRGs. In this evolutionary picture, submillimetre galaxies (SMGs) would host an AGN, which would eventually grow a black hole (BH) strong enough to blow off all of the gas and dust leaving an optically luminous QSO. To probe this evolutionary sequence we have focussed on the 'missing link' sources, which demonstrate both strong starburst (SB) and AGN signatures, in order to determine if the SB is the main power source even in SMGs when we have evidence that an AGN is present from their IRAC colours. The best way to determine if a dominant AGN is present is to look for their signatures in the mid-infrared with the Spitzer IRS, since often even deep X-ray observations miss identifying the presence of AGN in heavily dust-obscured SMGs. We present the results of our audit of the energy balance between star-formation and AGN within this special sub-population of SMGs -- where the BH has grown appreciably to begin heating the dust emission.Comment: 2 pages, 1 figure. To appear in "Hunting for the Dark: The Hidden Side of Galaxy Formation", Malta, 19-23 Oct. 2009, eds. V.P. Debattista and C.C. Popescu, AIP Conf. Ser., in pres

    Study of white privilege in K- 12 schools: minority teachersā€™ perspectives

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    The purpose of this dissertation is to capture and explore the existence of white privilege in K-12 schools through the perspective of minority educators. Further, my hope is to engage educators of all kind to begin conversations about white privilege in the schools; to deconstruct whiteness and its impact on education. This research brings forth voices of minority educators to shed light on conversations around race, whiteness and power in education. Today's educators must critically examine race and whiteness in order to break down barriers for children of color and create spaces where critical race consciousness is developed among students, parents, teachers and administrators. Not talking about race simply ignores it. By ignoring it, we are allowing systems of privilege to narrow mindedly influence education for us all. At the center of this dissertation lies a critical race theory foundation that calls one to challenge the experiences of whites as the normative standard. The null voices of minority educators are no longer acceptable within a critical race theory lens. Using narrative research design and semi structured interview questions, I was able to describe the experiences around white privilege from six minority educators. Dominant and emerging themes emerged including: Power Advantage, Exclusivity, Cultural Differences, Colorblind Ideology, Lack of Awareness or Understanding, Intentionality and Relationships

    Origins of the extragalactic background at 1mm from a combined analysis of the AzTEC and MAMBO data in GOODS-N

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    We present a study of the cosmic infrared background, which is a measure of the dust obscured activity in all galaxies in the Universe. We venture to isolate the galaxies responsible for the background at 1mm; with spectroscopic and photometric redshifts we constrain the redshift distribution of these galaxies. We create a deep 1.16mm map (sigma ~ 0.5mJy) by combining the AzTEC 1.1mm and MAMBO 1.2mm datasets in GOODS-N. This combined map contains 41 secure detections, 13 of which are new. By averaging the 1.16mm flux densities of individually undetected galaxies with 24um flux densities > 25uJy, we resolve 31--45 per cent of the 1.16mm background. Repeating our analysis on the SCUBA 850um map, we resolve a higher percentage (40--64 per cent) of the 850um background. A majority of the background resolved (attributed to individual galaxies) at both wavelengths comes from galaxies at z > 1.3. If the ratio of the resolved submillimeter to millimeter background is applied to a reasonable scenario for the origins of the unresolved submillimeter background, 60--88 per cent of the total 1.16mm background comes from galaxies at z > 1.3.Comment: 12 pages, 10 figures. Accepted by MNRAS. The combined map is publicly available at http://www.astro.umass.edu/~pope/goodsn_mm

    Stroke in children with posterior fossa brain malformations, hemangiomas, arterial anomalies, coarctation of the aorta and cardiac defects, and eye abnormalities (PHACE) syndrome: a systematic review of the literature.

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    Background and purposePHACE is an acronym for posterior fossa brain malformations, hemangiomas, arterial anomalies, coarctation of the aorta and cardiac defects, and eye abnormalities. Several case reports of arterial ischemic stroke (AIS) in individuals with PHACE have been published, but risk factors for AIS in PHACE have not been clearly defined. The objective of this article is to review all cases of stroke in PHACE in children and describe clinical characteristics that may be associated with an increased risk of AIS.MethodsA literature and registry search was conducted to identify patients with PHACE who had experienced AIS. Data were analyzed to determine age of onset, presenting signs and symptoms, and clinical features among this cohort compared with PHACE without AIS.ResultsTwenty-two individuals with PHACE and AIS were identified. Imaging of the arteries of the head and neck was reported in 20 of 22. Narrowing or nonvisualization of at least 1 great cerebral vessel was present in 19 of 20 and of those, 15 had ā‰„ 2 vessels involved. Aortic arch anomalies were reported in 13 of 22 individuals.ConclusionsAplasia, hypoplasia, or occlusion of a major cerebral artery appears to be a significant risk factor for AIS in children with PHACE, especially when >1 vessel is involved or if there is coarctation of the aorta

    An AzTEC 1.1 mm survey of the GOODS-N field ā€“ II. Multiwavelength identifications and redshift distribution

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    We present results from a multiwavelength study of 29 sources (false detection probabilities <5 per cent) from a survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field at 1.1 mm using the Astronomical Thermal Emission Camera (AzTEC). Comparing with existing 850 Ī¼m Submillimetre Common-User Bolometer Array (SCUBA) studies in the field, we examine differences in the source populations selected at the two wavelengths. The AzTEC observations uniformly cover the entire survey field to a 1Ļƒ depth of ~1 mJy. Searching deep 1.4 GHz Very Large Array (VLA) and Spitzer 3ā€“24 Ī¼m catalogues, we identify robust counterparts for 21 1.1 mm sources, and tentative associations for the remaining objects. The redshift distribution of AzTEC sources is inferred from available spectroscopic and photometric redshifts. We find a median redshift of z= 2.7 , somewhat higher than z= 2.0 for 850 Ī¼m selected sources in the same field, and our lowest redshift identification lies at a spectroscopic redshift z= 1.1460 . We measure the 850 Ī¼m to 1.1 mm colour of our sources and do not find evidence for '850 Ī¼m dropouts', which can be explained by the low signal-to-noise ratio of the observations. We also combine these observed colours with spectroscopic redshifts to derive the range of dust temperatures T, and dust emissivity indices Ī² for the sample, concluding that existing estimates T ~ 30 K and Ī² ~ 1.75 are consistent with these new data

    Management of infantile hemangiomas during the COVID pandemic

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    This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.The COVIDā€19 pandemic has caused significant shifts in patient care including a steep decline in ambulatory visits and a marked increase in the use of telemedicine. Infantile hemangiomas (IH) can require urgent evaluation and risk stratification to determine which infants need treatment and which can be managed with continued observation. For those requiring treatment, prompt initiation decreases morbidity and improves longā€term outcomes. The Hemangioma Investigator Group has created consensus recommendations for management of IH via telemedicine. FDA/EMAā€approved monitoring guidelines, clinical practice guidelines, and relevant, upā€toā€date publications regarding initiation and monitoring of betaā€blocker therapy were used to inform the recommendations. Clinical decisionā€making guidelines about when telehealth is an appropriate alternative to inā€office visits, including medication initiation, dosage changes, and ongoing evaluation, are included. The importance of communication with caregivers in the context of telemedicine is discussed, and online resources for both hemangioma education and propranolol therapy are provided

    Comparative genomics of Cluster O mycobacteriophages

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    Mycobacteriophages - viruses of mycobacterial hosts - are genetically diverse but morphologically are all classified in the Caudovirales with double-stranded DNA and tails. We describe here a group of five closely related mycobacteriophages - Corndog, Catdawg, Dylan, Firecracker, and YungJamal - designated as Cluster O with long flexible tails but with unusual prolate capsids. Proteomic analysis of phage Corndog particles, Catdawg particles, and Corndog-infected cells confirms expression of half of the predicted gene products and indicates a non-canonical mechanism for translation of the Corndog tape measure protein. Bioinformatic analysis identifies 8-9 strongly predicted SigA promoters and all five Cluster O genomes contain more than 30 copies of a 17 bp repeat sequence with dyad symmetry located throughout the genomes. Comparison of the Cluster O phages provides insights into phage genome evolution including the processes of gene flux by horizontal genetic exchange

    Complete Genome Sequences of Cluster A Mycobacteriophages BobSwaget, Fred313, KADY, Lokk, MyraDee, Stagni, and StepMih

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    Seven mycobacteriophages from distinct geographical locations were isolated, using Mycobacterium smegmatis mc2155 as the host, and then purified and sequenced. All of the genomes are related to cluster A mycobacteriophages, BobSwaget and Lokk in subcluster A2; Fred313, KADY, Stagni, and StepMih in subcluster A3; and MyraDee in subcluster A18, the first phage to be assigned to that subcluster

    Comparative Genomics of Cluster O Mycobacteriophages

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    Mycobacteriophages ā€“ viruses of mycobacterial hosts ā€“ are genetically diverse but morphologically are all classified in the Caudovirales with double-stranded DNA and tails. We describe here a group of five closely related mycobacteriophages ā€“ Corndog, Catdawg, Dylan, Firecracker, and YungJamal ā€“ designated as Cluster O with long flexible tails but with unusual prolate capsids. Proteomic analysis of phage Corndog particles, Catdawg particles, and Corndog-infected cells confirms expression of half of the predicted gene products and indicates a non-canonical mechanism for translation of the Corndog tape measure protein. Bioinformatic analysis identifies 8ā€“9 strongly predicted SigA promoters and all five Cluster O genomes contain more than 30 copies of a 17 bp repeat sequence with dyad symmetry located throughout the genomes. Comparison of the Cluster O phages provides insights into phage genome evolution including the processes of gene flux by horizontal genetic exchange
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