16 research outputs found
M87: A Misaligned BL LAC?
The nuclear region of M87 was observed with the Faint Object Spectrograph
(FOS) on the Hubble Space Telescope (HST) at 6 epochs, spanning 18 months,
after the HST image quality was improved with the deployment of the corrective
optics (COSTAR) in December 1993. From the FOS target acquisition data, we have
established that the flux from the optical nucleus of M87 varies by a factor ~2
on time scales of ~2.5 months and by as much as 25% over 3 weeks, and remains
unchanged (<= 2.5%) on time scales of ~1 day. The changes occur in an
unresolved central region <= 5 pc in diameter, with the physical size of the
emitting region limited by the observed time scales to a few hundred
gravitational radii. The featureless continuum spectrum becomes bluer as it
brightens while emission lines remain unchanged. This variability combined with
the observations of the continuum spectral shape, strong relativistic boosting
and the detection of significant superluminal motions in the jet, strongly
suggest that M87 belongs to the class of BL Lac objects but is viewed at an
angle too large to reveal the classical BL Lac properties.Comment: 12 pages, 3 Postscript figure
Long-Term Connectome Analysis Reveals Reshaping of Visual, Spatial Networks in a Model With Vascular Dementia Features
Background: Connectome analysis of neuroimaging data is a rapidly expanding field that offers the potential to diagnose, characterize, and predict neurological disease. Animal models provide insight into biological mechanisms that underpin disease, but connectivity approaches are currently lagging in the rodent. Methods: We present a pipeline adapted for structural and functional connectivity analysis of the mouse brain, and we tested it in a mouse model of vascular dementia. Results: We observed lacunar infarctions, microbleeds, and progressive white matter change across 6 months. For the first time, we report that default mode network activity is disrupted in the mouse model. We also identified specific functional circuitry that was vulnerable to vascular stress, including perturbations in a sensorimotor, visual resting state network that were accompanied by deficits in visual and spatial memory tasks. Conclusions: These findings advance our understanding of the mouse connectome and provide insight into how it can be altered by vascular insufficiency
Impaired serine metabolism complements LRRK2-G2019S pathogenicity in PD patients
Parkinson's disease (PD) is a multifactorial disorder with complex etiology. The most prevalent PD associated mutation, LRRK2-G2019S is linked to familial and sporadic cases. Based on the multitude of genetic predispositions in PD and the incomplete penetrance of LRRK2-G2019S, we hypothesize that modifiers in the patients' genetic background act as susceptibility factors for developing PD. To assess LRRK2-G2019S modifiers, we used human induced pluripotent stem cell-derived neuroepithelial stem cells (NESCs). Isogenic controls distinguish between LRRK2-G2019S dependent and independent cellular phenotypes. LRRK2-G2019S patient and healthy mutagenized lines showed altered NESC self-renewal and viability, as well as impaired serine metabolism. In patient cells, phenotypes were only partly LRRK2-G2019S dependent, suggesting a significant contribution of the genetic background. In this context we identified the gene serine racemase (SRR) as a novel patient-specific, developmental, genetic modifier contributing to the aberrant phenotypes. Its enzymatic product, n-serine, rescued altered cellular phenotypes. Susceptibility factors in the genetic background, such as SRR, could be new targets for early PD diagnosis and treatment.Analytical BioScience
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Design and Implementation of a CO2 Flood Utilizing Advanced Reservoir Characterization and Horizontal Injection Wells in a Shallow Shelf Carbonate Approaching Waterflood Depletion
Psychology and aggression
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68264/2/10.1177_002200275900300301.pd
Computer virus security in the Department of the Navy
This thesis discusses the growing threat of computer viruses and their impact on
Automated Information Systems. In particular, it attempts to show a need to establish
sound security programs that properly address computer viruses. A major area of the
thesis focuses on current guidance by the Department of Defense and the Department of
the Navy and provides recommendation for an effective Navy organization to effectively
combat the security threat from computer viruses. This thesis focuses on viruses gernerally
associated with personal computer systems and PC based local area networks. However,
the policies, guidelines and organizational measures presented in this paper are applicable
to larger computer systems and networks.http://archive.org/details/computervirussec00saltLieutenant, United States NavyApproved for public release; distribution is unlimited