497 research outputs found
Law Libraries and Laboratories: The Legacies of Langdell and His Metaphor
Law Librarians and others have often referred to Harvard Law School Dean C.C. Langdellâs statements that the law library is the lawyerâs laboratory. Professor Danner examines the context of what Langdell through his other writings, the educational environment at Harvard in the late nineteenth century, and the changing perceptions of university libraries generally. He then considers how the âlaboratory metaphorâ has been applied by librarians and legal scholars during the twentieth century and into the twenty-first. The article closes with thoughts on Langdellâs legacy for law librarians and the usefulness of the laboratory metaphor
HST FOC spectroscopy of the NLR of NGC 4151. I. Gas kinematics
We present the results from a detailed kinematic analysis of both
ground-based, and Hubble Space Telescope/Faint Object Camera long-slit
spectroscopy at sub-arcsec spatial resolution, of the narrow-line region of NGC
4151. In agreement with previous work, the extended emission gas (R > 4") is
found to be in normal rotation in the galactic plane, a behaviour that we were
able to trace even across the nuclear region, where the gas is strongly
disturbed by the interaction with the radio jet, and connects smoothly with the
large scale rotation defined by the neutral gas emission. The HST data, at
0.029" spatial resolution, allow us for the first time to truly isolate the
kinematic behaviour of the individual clouds in the inner narrow-line region.
We find that, underlying the perturbations introduced by the radio ejecta, the
general velocity field can still be well represented by planar rotation down to
a radius of ~ 0.5" (30 pc), distance at which the rotation curve has its
turnover.
The most striking result that emerges from our analysis is that the galaxy
potential derived fitting the rotation curve changes from a "dark halo" at the
ENLR distances to dominated by the central mass concentration in the NLR, with
an almost Keplerian fall-off in the 1"< R < 4" interval. The observed velocity
of the gas at 0.5" implies a mass of M ~ 10E9 M(sol) within the inner 60 pc.
The presence of a turnover in the rotation curve indicates that this central
mass concentration is extended. The first measured velocity point (outside the
region saturated by the nucleus) would imply an enclosed mass of ~ 5E7 M(sol)
within R ~ 0.15" (10 pc) which represents an upper limit to any nuclear point
mass.Comment: 30 pages (aaspp4.sty), 14 figures. Fig. 1, 2 and 4 available by
anonymous FTP at 143.54.2.51 (cd /pub/winge) as GIF files; or upon request to
[email protected]. Accepted for publication in the Astrophysical Journal
(part 1
High field x-ray diffraction study on a magnetic-field-induced valence transition in YbInCu4
We report the first high-field x-ray diffraction experiment using synchrotron
x-rays and pulsed magnetic fields exceeding 30 T. Lattice deformation due to a
magnetic-field-induced valence transition in YbInCu4 is studied. It has been
found that the Bragg reflection profile at 32 K changes significantly at around
27 T due to the structural transition. In the vicinity of the transition field
the low-field and the high-field phases are observed simultaneously as the two
distinct Bragg reflection peaks: This is a direct evidence of the fact that the
field-induced valence state transition is the first order phase transition. The
field-dependence of the low-field-phase Bragg peak intensity is found to be
scaled with the magnetization.Comment: 5 pages, 6 figures, submitted to J. Phys. Soc. Jp
No effect of ablation of surfactant protein-D on acute cerebral infarction in mice
BACKGROUND: Crosstalk between the immune system in the brain and the periphery may contribute to the long-term outcome both in experimental and clinical stroke. Although, the immune defense collectin surfactant protein-D (SP-D) is best known for its role in pulmonary innate immunity, SP-D is also known to be involved in extrapulmonary modulation of inflammation in mice. We investigated whether SP-D affected cerebral ischemic infarction and ischemia-induced inflammatory responses in mice. METHODS: The effect of SP-D was studied by comparing the size of ischemic infarction and the inflammatory and astroglial responses in SP-D knock out (KO) and wild type (WT) mice subjected to permanent middle cerebral artery occlusion. SP-D mRNA production was assessed in isolated cerebral arteries and in the whole brain by PCR, and SP-D protein in normal appearing and ischemic human brain by immunohistochemistry. Changes in plasma SP-D and TNF were assessed by ELISA and proximity ligation assay, respectively. RESULTS: Infarct volumetric analysis showed that ablation of SP-D had no effect on ischemic infarction one and five days after induction of ischemia. Further, ablation of SP-D had no effect on the ischemia-induced increase in TNF mRNA production one day after induction of ischemia; however the TNF response to the ischemic insult was affected at five days. SP-D mRNA was not detected in parenchymal brain cells in either naĂŻve mice or in mice subjected to focal cerebral ischemia. However, SP-D mRNA was detected in middle cerebral artery cells in WT mice and SP-D protein in vascular cells both in normal appearing and ischemic human brain tissue. Measurements of the levels of SP-D and TNF in plasma in mice suggested that levels were unaffected by the ischemic insult. Microglial-leukocyte and astroglial responses were comparable in SP-D KO and WT mice. CONCLUSIONS: SP-D synthesis in middle cerebral artery cells is consistent with SP-D conceivably leaking into the infarcted area and affecting local cytokine production. However, there was no SP-D synthesis in parenchymal brain cells and ablation of SP-D had no effect on ischemic cerebral infarction
Parsec-scale dust distributions in Seyfert galaxies - Results of the MIDI AGN snapshot survey
The emission of warm dust dominates the mid-infrared spectra of active
galactic nuclei (AGN). Only interferometric observations provide the necessary
angular resolution to resolve the nuclear dust and to study its distribution
and properties. The investigation of dust in AGN cores is hence one of the main
science goals for the MID-infrared Interferometric instrument MIDI at the VLTI.
As the first step, the feasibility of AGN observations was verified and the
most promising sources for detailed studies were identified. This was carried
out in a "snapshot survey" with MIDI using Guaranteed Time Observations. In the
survey, observations were attempted for 13 of the brightest AGN in the
mid-infrared which are visible from Paranal. The results of the three
brightest, best studied sources have been published in separate papers. Here we
present the interferometric observations for the remaining 10, fainter AGN. For
8 of these, interferometric measurements could be carried out. Size estimates
or limits on the spatial extent of the AGN-heated dust were derived from the
interferometric data of 7 AGN. These indicate that the dust distributions are
compact, with sizes on the order of a few parsec. The derived sizes roughly
scale with the square root of the luminosity in the mid-infrared, s ~ sqrt(L),
with no clear distinction between type 1 and type 2 objects. This is in
agreement with a model of nearly optically thick dust structures heated to T ~
300 K. For three sources, the 10 micron feature due to silicates is tentatively
detected either in emission or in absorption. Based on the results for all AGN
studied with MIDI so far, we conclude that in the mid-infrared the differences
between individual galactic nuclei are greater than the generic differences
between type 1 and type 2 objects.Comment: 18 pages, 8 figures, updated to version published in A&A 502, 67-8
Mean Diffusional Kurtosis in Patients with Glioma: Initial Results with a Fast Imaging Method in a Clinical Setting
ABSTRACT BACKGROUND AND PURPOSE: Diffusional kurtosis imaging is an MR imaging technique that provides microstructural information in biologic systems. Its application in clinical studies, however, is hampered by long acquisition and postprocessing times. We evaluated a new and fast (2 minutes 46 seconds) diffusional kurtosis imaging method with regard to glioma grading, compared it with conventional diffusional kurtosis imaging, and compared the diagnostic accuracy of fast mean kurtosis (MKĐ) to that of the widely used mean diffusivity
Protein profiling in hepatocellular carcinoma by label-free quantitative proteomics in two west african populations.
Background Hepatocellular Carcinoma is the third most common cause of cancer related death worldwide, often diagnosed by measuring serum AFP; a poor performance stand-alone biomarker. With the aim of improving on this, our study focuses on plasma proteins identified by Mass Spectrometry in order to investigate and validate differences seen in the respective proteomes of controls and subjects with LC and HCC. Methods Mass Spectrometry analysis using liquid chromatography electro spray ionization quadrupole time-of-flight was conducted on 339 subjects using a pooled expression profiling approach. ELISA assays were performed on four significantly differentially expressed proteins to validate their expression profiles in subjects from the Gambia and a pilot group from Nigeria. Results from this were collated for statistical multiplexing using logistic regression analysis. Results Twenty-six proteins were identified as differentially expressed between the three subject groups. Direct measurements of four; hemopexin, alpha-1-antitrypsin, apolipoprotein A1 and complement component 3 confirmed their change in abundance in LC and HCC versus control patients. These trends were independently replicated in the pilot validation subjects from Nigeria. The statistical multiplexing of these proteins demonstrated performance comparable to or greater than ALT in identifying liver cirrhosis or carcinogenesis. This exercise also proposed preliminary cut offs with achievable sensitivity, specificity and AUC statistics greater than reported AFP averages. Conclusions The validated changes of expression in these proteins have the potential for development into high-performance tests usable in the diagnosis and or monitoring of HCC and LC patients. The identification of sustained expression trends strengthens the suggestion of these four proteins as worthy candidates for further investigation in the context of liver disease. The statistical combinations also provide a novel inroad of analyses able to propose definitive cut-offs and combinations for evaluation of performance
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