1,524 research outputs found
A New Kind of Finance
Finance has benefited from the Wolfram's NKS approach but it can and will
benefit even more in the future, and the gains from the influence may actually
be concentrated among practitioners who unintentionally employ those principles
as a group.Comment: 13 pages; Forthcoming in "Irreducibility and Computational
Equivalence: 10 Years After Wolfram's A New Kind of Science," Hector Zenil,
ed., Springer Verlag, 201
“An ethnographic seduction”: how qualitative research and Agent-based models can benefit each other
We provide a general analytical framework for empirically informed agent-based simulations. This methodology provides present-day agent-based models with a sound and proper insight as to the behavior of social agents — an insight that statistical data often fall short of providing at least at a micro level and for hidden and sensitive populations. In the other direction, simulations can provide qualitative researchers in sociology, anthropology and other fields with valuable tools for: (a) testing the consistency and pushing the boundaries, of specific theoretical frameworks; (b) replicating and generalizing results; (c) providing a platform for cross-disciplinary validation of results
Reforming the Veterans Health Administration-Beyond Palliation of Symptoms
The Veterans Health Administration (VHA) is one of the largest health care delivery systems in the United States, with 9.1 million enrollees, 20,000 physicians, 1600 facilities, 288,000 employees, and a $59 billion budget. In response to highly publicized concerns regarding delayed access to care, preventable deaths in patients awaiting care, and falsification of lists to make waiting times appear shorter, Congress passed and President Barack Obama signed the Veterans Access, Choice, and Accountability Act of 2014. In addition to expanding non-VHA treatment options for veterans, this law requires a comprehensive, independent assessment of 12 areas of VHA care delivery and management (see box). Eleven assessments were
conducted under the Centers for Medicare and Medicaid Services Alliance to Modernize Healthcare, operated by the MITRE Corporation; the assessment of one area, “Access Standards,” was conducted by the Institute of Medicine. An independent blue-ribbon panel of experts was formed to examine and advise on all aspects of data collection and review, best practices, assessments, and recommendations. That panel, which we chaired, unanimously endorsed an integrated report, which was delivered to Secretary of Veterans Affairs Robert McDonald and Congress on September 1, 2015, and publicly released on September 18.
Probabilistic Inductive Classes of Graphs
Models of complex networks are generally defined as graph stochastic
processes in which edges and vertices are added or deleted over time to
simulate the evolution of networks. Here, we define a unifying framework -
probabilistic inductive classes of graphs - for formalizing and studying
evolution of complex networks. Our definition of probabilistic inductive class
of graphs (PICG) extends the standard notion of inductive class of graphs (ICG)
by imposing a probability space. A PICG is given by: (1) class B of initial
graphs, the basis of PICG, (2) class R of generating rules, each with
distinguished left element to which the rule is applied to obtain the right
element, (3) probability distribution specifying how the initial graph is
chosen from class B, (4) probability distribution specifying how the rules from
class R are applied, and, finally, (5) probability distribution specifying how
the left elements for every rule in class R are chosen. We point out that many
of the existing models of growing networks can be cast as PICGs. We present how
the well known model of growing networks - the preferential attachment model -
can be studied as PICG. As an illustration we present results regarding the
size, order, and degree sequence for PICG models of connected and 2-connected
graphs.Comment: 15 pages, 6 figure
Laser trabeculoplasty
Over a decade, laser trabeculoplasty has evolved from being a novel new treatment to one that is a commonly accepted intervention in the management of open-angle glaucoma. Despite its widespread use, however, there are still many unanswered questions about laser trabeculoplasty, including its mechanism of action and the ideal treatment parameters. In this review, we will discuss the history of the technique, the clinical experience, and some of the experimental studies that have been conducted to answer the questions regarding its mechanism of action.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29363/1/0000431.pd
A True Aneurysm of the Profunda Femoris Artery: A Case Report and Review of the English Language Literature
A rare case of true aneurysm of the profunda femoris artery (PFA) is reported. Surgical management consisted of ligation of the aneurysm and decompression of the sac. Presentation, diagnosis, and treatment of true PFA aneurysms are discussed and the English language literature is comprehensively reviewed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41367/1/10016_2004_Article_116.pd
Diabetes reduces bone marrow and circulating porcine endothelial progenitor cells, an effect ameliorated by atorvastatin and independent of cholesterol
Bone marrow derived endothelial progenitor cells (EPCs) are early precursors of mature endothelial cells which replenish aging and damaged endothelial cells. The authors studied a diabetic swine model to determine if induction of DM adversely affects either bone marrow or circulating EPCs and whether a HMG-CoA reductase inhibitor (statin) improves development and recruitment of EPCs in the absence of cholesterol lowering. Streptozotocin was administered to Yorkshire pigs to induce DM. One month after induction, diabetic pigs were treated with atorvastatin (statin, n = 10), ezetimibe (n = 10) or untreated (n = 10) and evaluated for number of bone marrow and circulating EPCs and femoral artery endothelial function. There was no effect of either medication on cholesterol level. One month after induction of DM prior to administration of drugs, the number of bone marrow and circulating EPCs significantly decreased (P < 0.0001) compared to baseline. Three months after DM induction, the mean proportion of circulating EPCs significantly increased in the atorvastatin group, but not in the control or ezetimibe groups. The control group showed progressive reduction in percentage of flow mediated vasodilatation (no dilatation at 3 months) whereas the atorvastatin group and ezetimibe exhibited vasodilatation, 6% and 4% respectively. DM results in significant impairment of bone marrow and circulating EPCs as well as endothelial function. The effect is ameliorated, in part, by atorvastatin independent of its cholesterol lowering effect. These data suggest a model wherein accelerated atherosclerosis seen with DM may, in part, result from reduction in EPCs which may be ameliorated by treatment with a statin
Gridded and direct Epoch of Reionisation bispectrum estimates using the Murchison Widefield Array
We apply two methods to estimate the 21~cm bispectrum from data taken within
the Epoch of Reionisation (EoR) project of the Murchison Widefield Array (MWA).
Using data acquired with the Phase II compact array allows a direct bispectrum
estimate to be undertaken on the multiple redundantly-spaced triangles of
antenna tiles, as well as an estimate based on data gridded to the -plane.
The direct and gridded bispectrum estimators are applied to 21 hours of
high-band (167--197~MHz; =6.2--7.5) data from the 2016 and 2017 observing
seasons. Analytic predictions for the bispectrum bias and variance for point
source foregrounds are derived. We compare the output of these approaches, the
foreground contribution to the signal, and future prospects for measuring the
bispectra with redundant and non-redundant arrays. We find that some triangle
configurations yield bispectrum estimates that are consistent with the expected
noise level after 10 hours, while equilateral configurations are strongly
foreground-dominated. Careful choice of triangle configurations may be made to
reduce foreground bias that hinders power spectrum estimators, and the 21~cm
bispectrum may be accessible in less time than the 21~cm power spectrum for
some wave modes, with detections in hundreds of hours.Comment: 19 pages, 10 figures, accepted for publication in PAS
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