187 research outputs found
Type II Quasars from the Sloan Digital Sky Survey: V. Imaging host galaxies with the Hubble Space Telescope
Type II quasars are luminous Active Galactic Nuclei whose centers are
obscured by large amounts of gas and dust. In this paper we present 3-band HST
images of nine type II quasars with redshifts 0.2 < z < 0.4 selected from the
Sloan Digital Sky Survey based on their emission line properties. The intrinsic
luminosities of these AGN are estimated to be -24 > M_B > -26, but optical
obscuration allows their host galaxies to be studied unencumbered by bright
nuclei. Each object has been imaged in three continuum filters (`UV', `blue'
and `yellow') placed between the strong emission lines. The spectacular, high
quality images reveal a wealth of details about the structure of the host
galaxies and their environments. Six of the nine galaxies in the sample are
ellipticals with de Vaucouleurs light profiles, one object has a well-defined
disk component and the remaining two have marginal disks. Stellar populations
of type II quasar hosts are more luminous (by a median of 0.3-0.7 mag,
depending on the wavelength) and bluer (by about 0.4 mag) than are M* galaxies
at the same redshift. When smooth fits to stellar light are subtracted from the
images, we find both positive and negative residuals that become more prominent
toward shorter wavelengths. We argue that the negative residuals are due to
kpc-scale dust obscuration, while most positive residuals are due to the light
from the nucleus scattered off interstellar material in the host galaxy.
Scattered light makes a significant contribution to the broad band continuum
emission and can be the dominant component of the extended emission in the UV
in extreme cases.Comment: 51 pages, including 12 grey scale figures, 4 color figures, 5 tables.
In press in AJ. Version with higher-resolution images available at
http://www.astro.princeton.edu/~nadia/qso2.html. (Minor changes in response
to the referee report
Large Cell Neuroendocrine Carcinoma of the Ampulla of Vater
Context Large cell neuroendocrine carcinomas of the ampulla of Vater are rare and confer a very poor prognosis despite aggressive therapy. There are few case reports of large cell neuroendocrine carcinomas of the ampulla of Vater in the literature and to date no studies have been done to establish optimal management. We describe a pooled case series from published reports of neuroendocrine carcinomas of the ampulla of Vater including a case which presented to our institution. Methods A narrative review was undertaken including all published English case reports of large cell neuroendocrine carcinomas of the ampulla of Vater. Our primary outcome was to determine the overall survival. Results Twenty cases of large cell neuroendocrine carcinomas of the ampulla of Vater were identified. Seventy-six percent of patients were reported to have died of disease with a mean survival of 11.8 months. Twenty percent of the tumours were associated with an adenoma. The approximate median survivals were 15 months for those with an associated adenoma and 11 months without. Conclusions This pooled analysis demonstrates both the rarity and poor prognosis of large cell neuroendocrine carcinomas of the ampulla of Vater. Although surgical resection is the mainstay of treatment, we review common adjuvant chemotherapy regimes. Prognosis may be improved when these tumours are associated with adenomas, however, further studies are needed.Image: Circumferential fleshy ulcerated tumour
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Chylous Ascites Post Open Cholecystectomy After Severe Pancreatitis
Context Chylous ascites a rare complication post cholecystectomy. There are to our knowledge only 3 reported cases in the literature. We describe a case of chylous ascites post open cholecystectomy in a patient with recent severe pancreatitis. We propose a potential relationship between acute biliary pancreatitis and the development of chylous ascites. Case report We present a 37 year old man with a history of severe biliary pancreatitis 10 months prior. He was electively admitted for laparoscopic cholecystectomy. His surgery was converted to open cholecystectomy due to adhesions. A closed, non suction drain was placed intraoperatively draining serosanguinous fluid. Two days post operatively the draining fluid changed to a milky colour fluid with high triglyceride level. Chylous ascites was confirmed clinically with a 24 hour fast. He was treated with total parenteral nutrition. His chylous ascites resolved with conservative management and his drain was removed. Conclusion We describe the diagnosis and management of chylous ascites post cholecystectomy. We propose the hypothesis to the aetiology of this rare condition, based on ours and one previous case, that a history of recent severe acute pancreatitis poses a risk factor in the development of chylous ascites
Robot Assisted Surgical Ward Rounds: Virtually Always There
Background: While an explosion in technological sophistication has revolutionized surgery within the operating theatre, delivery of surgical ward-based care has seen little innovation. Use of telepresence allowing off-site clinicians communicate with patients has been largely restricted to outpatient settings or use of complex, expensive, static devices. We designed a prospective study to ascertain feasibility and face validity of a remotely controlled mobile audiovisual drone (LUCY) to access inpatients. This device is, uniquely, lightweight, freely mobile and emulates ‘human’ interaction by swiveling and adjusting height to patients’ eye-level. Methods: Robot-assisted ward rounds(RASWR) were conducted over 3 months. A remotely located consultant surgeon communicated with patients/bedside teams via encrypted audiovisual telepresence robot (DoubleRoboticstm, California USA). Likert-scale satisfaction questionnaires, incorporating free-text sections for mixed-methods data collection, were disseminated to patient and staff volunteers following RASWRs. The same cohort completed a linked questionnaire following conventional (gold-standard) rounds, acting as control group. Data were paired, and non-parametric analysis performed. Results: RASWRs are feasible (>90% completed without technical difficulty). The RASWR(n=52 observations) demonstrated face validity with strong correlations (r>0.7; Spearman, p-value <0.05) between robotic and conventional ward rounds among patients and staff on core themes, including dignity/confidentiality/communication/satisfaction with management plan. Patients (96.08%, n=25) agreed RASWR were a satisfactory alternative when consultant physical presence was not possible. There was acceptance of nursing/NCHD cohort (100% (n=11) willing to regularly partake in RASWR). Conclusion: RASWRs receive high levels of patient and staff acceptance, and offer a valid alternative to conventional ward rounds when a consultant cannot be physically present
H2A.Z Acidic Patch Couples Chromatin Dynamics to Regulation of Gene Expression Programs during ESC Differentiation
The histone H2A variant H2A.Z is essential for embryonic development and for proper control of developmental gene expression programs in embryonic stem cells (ESCs). Divergent regions of amino acid sequence of H2A.Z likely determine its functional specialization compared to core histone H2A. For example, H2A.Z contains three divergent residues in the essential C-terminal acidic patch that reside on the surface of the histone octamer as an uninterrupted acidic patch domain; however, we know little about how these residues contribute to chromatin structure and function. Here, we show that the divergent amino acids Gly92, Asp97, and Ser98 in the H2A.Z C-terminal acidic patch (H2A.Z[superscript AP3]) are critical for lineage commitment during ESC differentiation. H2A.Z is enriched at most H3K4me3 promoters in ESCs including poised, bivalent promoters that harbor both activating and repressive marks, H3K4me3 and H3K27me3 respectively. We found that while H2A.Z[superscript AP3] interacted with its deposition complex and displayed a highly similar distribution pattern compared to wild-type H2A.Z, its enrichment levels were reduced at target promoters. Further analysis revealed that H2A.Z[superscript AP3] was less tightly associated with chromatin, suggesting that the mutant is more dynamic. Notably, bivalent genes in H2A.Z[superscript AP3] ESCs displayed significant changes in expression compared to active genes. Moreover, bivalent genes in H2A.Z[superscript AP3] ESCs gained H3.3, a variant associated with higher nucleosome turnover, compared to wild-type H2A.Z. We next performed single cell imaging to measure H2A.Z dynamics. We found that H2A.Z[superscript AP3] displayed higher mobility in chromatin compared to wild-type H2A.Z by fluorescent recovery after photobleaching (FRAP). Moreover, ESCs treated with the transcriptional inhibitor flavopiridol resulted in a decrease in the H2A.Z[superscript AP3] mobile fraction and an increase in its occupancy at target genes indicating that the mutant can be properly incorporated into chromatin. Collectively, our work suggests that the divergent residues in the H2A.Z acidic patch comprise a unique domain that couples control of chromatin dynamics to the regulation of developmental gene expression patterns during lineage commitment.Massachusetts Life Sciences Center (David H. Koch Institute for Integrative Cancer Research at MIT Core Grant P30-CA14051)National Science Foundation (U.S.). Emergent Behaviors of Integrated Cellular Systems (Grant CBET-0939511)MIT Faculty Start-up FundMassachusetts Institute of Technology. Computational and Systems Biology Initiative (Merck & Co. Postdoctoral Fellowship
3D modelling of the impact of stellar activity on tidally locked terrestrial exoplanets: atmospheric composition and habitability
Life and Liesegang: Outcrop-Scale Microbially Induced Diagenetic Structures and Geochemical Self-Organization Phenomena Produced by Oxidation of Reduced Iron
The Kanab Wonderstone is sandstone (Shinarump Member, Chinle Formation) that is cemented and stained with iron oxide. The iron-oxide cementation and staining in these rocks have been considered examples of the Liesegang phenomenon, but we will show that they comprise a microbially induced structure. The spacing of bands of iron-oxide stain follow the Jablczynski spacing law (wherein the spacing between bands of iron-oxide stain increases as one traverses a series of bands) characteristic of Liesegang. Bands of iron-oxide cement exhibit more variable spacing and exhibit a weak but significant correlation between band thickness and distance between bands of cement. The pore-filling cement contains morphotypes that are similar in size and habit to those exhibited by microaerophilic iron-oxidizing bacteria. Other disseminated iron-oxide mineralization occurs as rhombohedra interpreted to be pseudomorphs after siderite. We interpret the cement to be produced by microbially mediated oxidation of siderite (a typical early diagenetic mineral in fluvial sandstones). Iron-oxidizing bacteria colonized the redox interface between siderite-cemented sand and porous sandstone. Microbes oxidized aqueous Fe(II), generating acid that caused siderite dissolution. The iron-oxide cement is the microbial product of a geochemical drive for organization; whereas the iron-oxide stain is true Liesegang. Together, they comprise a distinctive microbially induced structure with high preservation potential. Key Words: Biosignatures—Iron oxides—Diagenesis—Iron-oxidizing bacteria—Shinarump
Multi-omic biomarker panel in pancreatic cyst fluid and serum predicts patients at a high risk of pancreatic cancer development
Integration of multi-omic data for the purposes of biomarker discovery can provide novel and robust panels across multiple biological compartments. Appropriate analytical methods are key to ensuring
accurate and meaningful outputs in the multi-omic setting. Here, we extensively profile the proteome and transcriptome of patient pancreatic cyst fluid (PCF) (n=32) and serum (n=68), before integrating matched omic and biofluid data, to identify biomarkers of pancreatic cancer risk. Differential expression analysis, feature reduction, multi-omic data integration, unsupervised hierarchical clustering, principal component analysis, spearman correlations and leave-one-out cross-validation
were performed using RStudio and CombiROC software. An 11-feature multi-omic panel in PCF [PIGR, S100A8, REG1A, LGALS3, TCN1, LCN2, PRSS8, MUC6, SNORA66, miR-216a-5p, miR-216b-5p] generated an AUC=0.806. A 13-feature multi-omic panel in serum [SHROOM3, IGHV3-72, IGJ, IGHA1, PPBP, APOD, SFN, IGHG1, miR-197-5p, miR-6741-5p, miR-3180, miR-3180-3p, miR-6782-5p] produced an AUC=0.824. Integration of the strongest performing biomarkers generated a 10-feature crossbiofluid multi-omic panel [S100A8, LGALS3, SNORA66, miR-216b-5p, IGHV3-72, IGJ, IGHA1, PPBP, miR-3180, miR-3180-3p] with an AUC=0.970. Multi-omic profiling provides an abundance of potential biomarkers. Integration of data from different omic compartments, and across biofluids, produced a biomarker panel that performs with high accuracy, showing promise for the risk stratification of
patients with pancreatic cystic lesions
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