762 research outputs found
Multifocal High-Grade Pancreatic Precursor Lesions: A Case Series and Management Recommendations
Background: The risk of developing invasive cancer in the remnant pancreas after resection of multifocal high-grade pancreatic precursor lesions is not well known. We report three patients who were followed up after resection of multifocal high-grade pancreatic intraepithelial neoplasia (PanIN)-3 or intraductal papillary mucinous neoplasia (IPMN), two of whom eventually developed invasive carcinoma. Presentation: 1) 68-year-old woman who had a laparoscopic distal pancreatectomy for multifocal mixed-type IPMN, identified as high-grade on final pathology, with negative surgical margins. During semiannual monitoring, eight years from the first surgery, the patient developed suspicious features prompting surgical resection of the body with final pathology revealing invasive ductal adenocarcinoma in the setting of IPMN. 2) 48-year-old woman who had a distal pancreatectomy for severe acute/chronic symptomatic pancreatitis, with final pathology revealing multifocal high-grade PanIN-3, with negative surgical margins. Despite semiannual monitoring, two years from the first surgery, the patient developed pancreatic adenocarcinoma with liver metastasis. 3) 55-year-old woman who had a Whipple procedure for symptomatic chronic pancreatitis, with multifocal PanIN-3 on final pathology. The patient underwent completion pancreatectomy due to symptomatology and her high-risk profile, with final pathology confirming multifocal PanIN-3. Conclusion: Multifocal high-grade dysplastic lesions of the pancreas might benefit from surgical resection
The Black Hole-Bulge Relationship in Luminous Broad-Line Active Galactic Nuclei and Host Galaxies
We have measured the stellar velocity dispersions (\sigma_*) and estimated
the central black hole (BH) masses for over 900 broad-line active galactic
nuclei (AGNs) observed with the Sloan Digital Sky Survey. The sample includes
objects which have redshifts up to z=0.452, high quality spectra, and host
galaxy spectra dominated by an early-type (bulge) component. The AGN and host
galaxy spectral components were decomposed using an eigenspectrum technique.
The BH masses (M_BH) were estimated from the AGN broad-line widths, and the
velocity dispersions were measured from the stellar absorption spectra of the
host galaxies. The range of black hole masses covered by the sample is
approximately 10^6 < M_BH < 10^9 M_Sun. The host galaxy luminosity-velocity
dispersion relationship follows the well-known Faber-Jackson relation for
early-type galaxies, with a power-law slope 4.33+-0.21. The estimated BH masses
are correlated with both the host luminosities (L_{H}) and the stellar velocity
dispersions (\sigma_*), similar to the relationships found for low-redshift,
bulge-dominated galaxies. The intrinsic scatter in the correlations are large
(~0.4 dex), but the very large sample size allows tight constraints to be
placed on the mean relationships: M_BH ~ L_H^{0.73+-0.05} and M_BH ~
\sigma_*^{3.34+-0.24}. The amplitude of the M_BH-\sigma_* relation depends on
the estimated Eddington ratio, such that objects with larger Eddington ratios
have smaller black hole masses than expected at a given velocity dispersion.Comment: Accepted for publication in A
Spectral Classification of Quasars in the Sloan Digital Sky Survey: Eigenspectra; Redshift and Luminosity Effects
We study 16,707 quasar spectra from the SDSS using the Karhunen-Lo\`eve (KL)
transform (or Principal Component Analysis, PCA). The quasar eigenspectra of
the full catalog reveal the following: 1st order - the mean spectrum; 2nd order
- a host-galaxy component; 3rd order - the UV-optical continuum slope; 4th
order - the correlations of Balmer emission lines. We find that the spectral
classification of quasars is redshift and luminosity dependent, as such there
does not exist a compact set (< 10 modes) of eigenspectra (covering 900 to 8000
angstrom) which can describe most variations (> 95%) of the entire catalog. We
therefore construct several sets of eigenspectra in different redshift and
luminosity bins. From these eigenspectra we find that quasar spectra can be
classified (by the first two eigenspectra) into a sequence that is defined by a
simple progression in the steepness of the slope of the continuum. We also find
a dependence on redshift and luminosity in the eigencoefficients. The dominant
redshift effect is a result of the evolution of the blended FeII emission
(optical) and the Balmer continuum (the ``small bump''). A luminosity
dependence is also present in the eigencoefficients and is related to the
Baldwin effect. The eigenspectra constructed from the wavelength-selected SDSS
spectra are found to agree with the principal components by Francis et al.
(1992) and the well-known ``Eigenvector-1'' (Boroson and Green 1992).
(Abridged)Comment: AJ accepted. 65 pages, 27 figures, 9 tables. Resolutions of some
figures are lowere
Muon-Spin Rotation Measurements of the Magnetic Field Dependence of the Vortex-Core Radius and Magnetic Penetration Depth in NbSe2
Muon-spin rotation spectroscopy has been used to measure the internal
magnetic field distribution in NbSe2 for Hc1 << H < 0.25 Hc2. The deduced
profiles of the supercurrent density indicate that the vortex-core radius in
the bulk decreases sharply with increasing magnetic field. This effect, which
is attributed to increased vortex-vortex interactions, does not agree with the
dirty-limit microscopic theory. A simple phenomenological equation in which the
core radius depends on the intervortex spacing is used to model this behaviour.
In addition, we find for the first time that the in-plane magnetic penetration
depth increases linearly with H in the vortex state of a conventional
superconductor.Comment: 4 pages, RevTeX, 4 encapsulated postscript figures, (to appear in
Phys. Rev. Lett. 25Aug97 issue
An SU(N) Mott insulator of an atomic Fermi gas realized by large-spin Pomeranchuk cooling
The Hubbard model, containing only the minimum ingredients of nearest
neighbor hopping and on-site interaction for correlated electrons, has
succeeded in accounting for diverse phenomena observed in solid-state
materials. One of the interesting extensions is to enlarge its spin symmetry to
SU(N>2), which is closely related to systems with orbital degeneracy. Here we
report a successful formation of the SU(6) symmetric Mott insulator state with
an atomic Fermi gas of ytterbium (173Yb) in a three-dimensional optical
lattice. Besides the suppression of compressibility and the existence of charge
excitation gap which characterize a Mott insulating phase, we reveal an
important difference between the cases of SU(6) and SU(2) in the achievable
temperature as the consequence of different entropy carried by an isolated
spin. This is analogous to Pomeranchuk cooling in solid 3He and will be helpful
for investigating exotic quantum phases of SU(N) Hubbard system at extremely
low temperatures.Comment: 20 pages, 6 figures, to appear in Nature Physic
NTT and NOT spectroscopy of SDSS-II supernovae
Context. The SDSS-II Supernova Survey, conducted between 2005 and 2007, was
designed to detect a large number of Type Ia supernovae (SNe Ia) around z~0.2,
the redshift "gap" between low-z and high-z SN searches. The survey has
provided multi-band photometric lightcurves for variable targets, and SN
candidates were scheduled for spectroscopic observations, primarily to provide
SN classification and accurate redshifts. We present SN spectra obtained in
2006 and 2007 using the NTT and the NOT. Aims. We provide an atlas of SN
spectra in the range z =0.03-0.32 that complements the well-sampled lightcurves
from SDSS-II in the forthcoming three-year SDSS SN cosmology analysis. The
sample can, for example, be used for spectral studies of SNe Ia, which are
critical for understanding potential systematic effects when SNe are used to
determine cosmological distances. Methods. The spectra were reduced in a
uniform manner, and special care was taken in estimating the uncertainties for
the different processing steps. Host-galaxy light was subtracted when possible
and the SN type fitted using the SuperNova IDentification code (SNID). We also
present comparisons between spectral and photometric dating using SALT
lightcurve fits to the photometry from SDSS-II, as well as the global
distribution of our sample in terms of the lightcurve parameters: stretch and
colour. Results. We report new spectroscopic data from 141 SNe Ia, mainly
between -9 and +15 days from lightcurve maximum, including a few cases of
multi-epoch observations. This homogeneous, host-galaxy subtracted, SN Ia
spectroscopic sample is among the largest such data sets and unique in its
redshift interval. The sample includes two potential SN 1991T-like SNe (SN
2006on and SN 2007ni) and one potential SN 2002cx-like SN (SN 2007ie). In
addition, the new compilation includes spectra from 23 confirmed Type II and 8
Type Ib/c SNe.Comment: Accepted for publication in A&
Routine Gastric Decompression after Pancreatoduodenectomy: Treating the Surgeon?
Background
The decision to routinely leave a nasogastric tube after pancreatoduodenectomy remains controversial. We sought to determine the impact of immediate nasogastric tube removal versus early nasogastric tube removal (<24 h) on postoperative outcomes.
Methods
A retrospective review of our institutionās prospective ACS-NSQIP database identified patients that underwent pancreatoduodenectomy from 2015 to 2018. Outcomes were compared among patients with immediate nasogastric tube removal versus early nasogastric tube removal.
Results
A total of 365 patients were included in primary analysis (no nasogastric tube, n = 99; nasogastric tube removed 0.05). Incidence of delayed gastric emptying (11.1 versus 13.2%) was similar between groups. Patients with no nasogastric tube less frequently required nasogastric tube reinsertion (n = 4, 4%) compared to patients with NGT <24 h (n = 39, 15%) (OR = 3.83, 95% CI [1.39-10.58]; P = 0.009).
Conclusion
Routine gastric decompression can be safely avoided after uneventful pancreaticoduodenectomy
Global protease activity profiling provides differential diagnosis of pancreatic cysts
Purpose: Pancreatic cysts are estimated to be present in 2%-3% of the adult population. Unfortunately, current diagnostics do not accurately distinguish benign cysts from those that can progress into invasive cancer. Misregulated pericellular proteolysis is a hallmark of malignancy, and therefore, we used a global approach to discover protease activities that differentiate benign nonmucinous cysts from premalignant mucinous cysts.Experimental Design: We employed an unbiased and global protease profiling approach to discover protease activities in 23 cyst fluid samples. The distinguishing activities of select proteases was confirmed in 110 samples using specific fluorogenic substrates and required less than 5 Ī¼L of cyst fluid.Results: We determined that the activities of the aspartyl proteases gastricsin and cathepsin E are highly increased in fluid from mucinous cysts. IHC analysis revealed that gastricsin expression was associated with regions of low-grade dysplasia, whereas cathepsin E expression was independent of dysplasia grade. Gastricsin activity differentiated mucinous from nonmucinous cysts with a specificity of 100% and a sensitivity of 93%, whereas cathepsin E activity was 92% specific and 70% sensitive. Gastricsin significantly outperformed the most widely used molecular biomarker, carcinoembryonic antigen (CEA), which demonstrated 94% specificity and 65% sensitivity. Combined analysis of gastricsin and CEA resulted in a near perfect classifier with 100% specificity and 98% sensitivity.Conclusions: Quantitation of gastricsin and cathepsin E activities accurately distinguished mucinous from nonmucinous pancreatic cysts and has the potential to replace current diagnostics for analysis of these highly prevalent lesions. Clin Cancer Res; 23(16); 4865-74. Ā©2017 AACR
Unification of Luminous Type 1 Quasars through CIV Emission
Using a sample of 30,000 quasars from SDSS-DR7, we explore the range of
properties exhibited by high-ionization, broad emission lines, such as CIV
1549. Specifically we investigate the anti-correlation between L_UV and
emission line EQW (the Baldwin Effect) and the "blueshifting" of
high-ionization emission lines. The blueshift of the CIV emission line is
nearly ubiquitous, with a mean shift of 810 km/s for radio-quiet (RQ) quasars
and 360 km/s for radio-loud (RL) quasars, and the Baldwin Effect is present in
both RQ and RL samples. Composite spectra are constructed as a function of CIV
emission line properties in attempt to reveal empirical relationships between
different line species and the SED. Within a two-component disk+wind model of
the broad emission line region (BELR), where the wind filters the continuum
seen by the disk component, we find that RL quasars are consistent with being
dominated by the disk component, while BALQSOs are consistent with being
dominated by the wind component. Some RQ objects have emission line features
similar to RL quasars; they may simply have insufficient black hole (BH) spin
to form radio jets. Our results suggest that there could be significant
systematic errors in the determination of L_bol and BH mass that make it
difficult to place these findings in a more physical context. However, it is
possible to classify quasars in a paradigm where the diversity of BELR
parameters are due to differences in an accretion disk wind between quasars
(and over time); these differences are underlain primarily by the SED, which
ultimately must be tied to BH mass and accretion rate.Comment: 51 pages, 18 figures, accepted by AJ, revised version includes
various modifications based on the referee's comment
Dimethylaminoparthenolide and gemcitabine: a survival study using a genetically engineered mouse model of pancreatic cancer
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