367 research outputs found
Knowledge discovery in corporate email : the compliance bot meets Enron
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management, 2006.Includes bibliographical references (leaves 101-107).I propose the creation of a real-time compliance "bot" - software to momentarily pause each employee's email at the moment of sending and to electronically assess whether that email is likely to create liability or unanticipated expense for the corporation. My thesis describes the confluence of historical events making such a product necessary and desirable - increase in corporate regulation, explosive growth of email, acceptance of email as evidence in litigation. The cautionary tale of Enron provides the backdrop for the thesis. The government released hundreds of thousands of Enron management emails and they have become research fodder for those interested in "Knowledge Discovery," a computer science discipline that gleans meaningful information from data otherwise indecipherable due to its sheer size. CEO's and other C-level corporate managers are my intended audience, so I have attempted to counter the weightiness of the technical topics by focusing on the search for readily understandable management headaches such as the loss of productivity due to high participation in the fantasy football pool or the potential for dirty jokes to become evidence in an employment law claim.by K. Krasnow Waterman.M.B.A
Prototyping Fusion Center information sharing; implementing policy reasoning over cross-jurisdictional data transactions occurring in a decentralized environment
Abstract—In 2004, the White House and then Congress deter-mined there should be an “Information Sharing Environment” that facilitates the flow of critical information for counter-terrorism, related law enforcement, and disaster management activities. That work has been progressing but a major challenge is how to create technologies that: ensure compliance with laws and policies of the federal government, 50 states, and individual agencies; pass appropriate data that would support access control and privilege decisions in different jurisdictions; and achieve accountability and transparency for this activity. We have built a prototype of Fusion Center information sharing that shows significant progress in the representation of law in a policy language, the reasoning of that law over data transactions occurring in a web environment (internet or intranet), acquiring necessary information from authoritative sources wherever they reside in the decentralized environment, and providing both a binary response suitable for automated workflow implementation and a detailed justification suitable for human validation of the conclusion. In this paper, we briefly describe the technologies employed for serializing the data and policy, reasoning over the rules contained in the policy, and displaying the results to users. These combine to provide a powerful tool to support a range of necessary governmental functions including access control, privilege management, audit, periodic reporting, or risk modeling. I
Radial Construction of an Arterial Wall
SummarySome of the most serious diseases involve altered size and structure of the arterial wall. Elucidating how arterial walls are built could aid understanding of these diseases, but little is known about how concentric layers of muscle cells and the outer adventitial layer are assembled and patterned around endothelial tubes. Using histochemical, clonal, and genetic analysis in mice, here we show that the pulmonary artery wall is constructed radially, from the inside out, by two separate but coordinated processes. One is sequential induction of successive cell layers from surrounding mesenchyme. The other is controlled invasion of outer layers by inner layer cells through developmentally regulated cell reorientation and radial migration. We propose that a radial signal gradient controls these processes and provide evidence that PDGF-B and at least one other signal contribute. Modulation of such radial signaling pathways may underlie vessel-specific differences and pathological changes in arterial wall size and structure.Video Abstrac
Critical exponents for random knots
The size of a zero thickness (no excluded volume) polymer ring is shown to
scale with chain length in the same way as the size of the excluded volume
(self-avoiding) linear polymer, as , where . The
consequences of that fact are examined, including sizes of trivial and
non-trivial knots.Comment: 4 pages, 0 figure
Generation of human motor units with functional neuromuscular junctions in microfluidic devices
Neuromuscular junctions (NMJs) are specialized synapses between the axon of the lower motor neuron and the muscle facilitating the engagement of muscle contraction. In motor neuron disorders, such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), NMJs degenerate, resulting in muscle atrophy and progressive paralysis. The underlying mechanism of NMJ degeneration is unknown, largely due to the lack of translatable research models. This study aimed to create a versatile and reproducible in vitro model of a human motor unit with functional NMJs. Therefore, human induced pluripotent stem cell (hiPSC)-derived motor neurons and human primary mesoangioblast (MAB)-derived myotubes were co-cultured in commercially available microfluidic devices. The use of fluidically isolated micro-compartments allows for the maintenance of cell-specific microenvironments while permitting cell-to-cell contact through microgrooves. By applying a chemotactic and volumetric gradient, the growth of motor neuron-neurites through the microgrooves promoting myotube interaction and the formation of NMJs were stimulated. These NMJs were identified immunocytochemically through co-localization of motor neuron presynaptic marker synaptophysin (SYP) and postsynaptic acetylcholine receptor (AChR) marker α-bungarotoxin (Btx) on myotubes and characterized morphologically using scanning electron microscopy (SEM). The functionality of the NMJs was confirmed by measuring calcium responses in myotubes upon depolarization of the motor neurons. The motor unit generated using standard microfluidic devices and stem cell technology can aid future research focusing on NMJs in health and disease
Evaluation of the clinical value of bone metabolic parameters for the screening of osseous metastases compared to bone scintigraphy
BACKGROUND: Bone metastases are common in many types of cancer. As screening methods different imaging modalities are available. A new approach for the screening of osseous metastases represents the measurement of bone metabolic markers. Therefore aim of this study was to evaluate the usefulness of the determination of bone metabolic markers aminoterminal propeptide of type I procollagen (PINP, osteoblastic activity) and the carboxyterminal pyridinoline cross-linked telopeptide of type I collagen (ICTP, osteoclastic activity) for the detection of bone metastases associated with other malignancies. METHODS: 88 patients aged 21 – 82 years with malignant tumors were prospectively studied. The serum concentrations of PINP and ICTP were measured and compared to the results of bone scintigraphy, radiological bone series, CT, MRI and clinical follow-up. RESULTS: Osseous metastases were found in 21 patients. 19 of them were correctly identified by bone scintigraphy (sensitivity: 90%). For bone metabolic markers results were as follows: ICTP sensitivity: 71%, specificity: 42%; PINP sensitivity: 24%, specificity: 96%. CONCLUSIONS: As markers of bone metabolism PINP and ICTP showed low sensitivity and/or specificity for the detection of osseous metastases. The presented markers did not seem to be sufficient enough to identify patients with bone metastases or to replace established screening methods
PICH promotes sister chromatid disjunction and co-operates with topoisomerase II in mitosis
PICH is a SNF2 family DNA translocase that binds to ultra-fine DNA bridges (UFBs) in
mitosis. Numerous roles for PICH have been proposed from protein depletion experiments,
but a consensus has failed to emerge. Here, we report that deletion of PICH in avian cells
causes chromosome structural abnormalities, and hypersensitivity to an inhibitor of
Topoisomerase II (Topo II), ICRF-193. ICRF-193-treated PICH-/- cells undergo sister
chromatid non-disjunction in anaphase, and frequently abort cytokinesis. PICH co-localises
with Topo IIα on UFBs and at the ribosomal DNA locus, and the timely resolution of both
structures depends on the ATPase activity of PICH. Purified PICH protein strongly
stimulates the catalytic activity of Topo II in vitro. Consistent with this, a human PICH-/- cell
line exhibits chromosome instability and chromosome condensation and decatenation
defects similar to those of ICRF-193-treated cells. We propose that PICH and Topo II
cooperate to prevent chromosome missegregation events in mitosis
Order and Stochastic Dynamics in Drosophila Planar Cell Polarity
Cells in the wing blade of Drosophila melanogaster exhibit an in-plane polarization causing distal orientation of hairs. Establishment of the Planar Cell Polarity (PCP) involves intercellular interactions as well as a global orienting signal. Many of the genetic and molecular components underlying this process have been experimentally identified and a recently advanced system-level model has suggested that the observed mutant phenotypes can be understood in terms of intercellular interactions involving asymmetric localization of membrane bound proteins. Among key open questions in understanding the emergence of ordered polarization is the effect of stochasticity and the role of the global orienting signal. These issues relate closely to our understanding of ferromagnetism in physical systems. Here we pursue this analogy to understand the emergence of PCP order. To this end we develop a semi-phenomenological representation of the underlying molecular processes and define a “phase diagram” of the model which provides a global view of the dependence of the phenotype on parameters. We show that the dynamics of PCP has two regimes: rapid growth in the amplitude of local polarization followed by a slower process of alignment which progresses from small to large scales. We discuss the response of the tissue to various types of orienting signals and show that global PCP order can be achieved with a weak orienting signal provided that it acts during the early phase of the process. Finally we define and discuss some of the experimental predictions of the model
Serrano (Sano) Functions with the Planar Cell Polarity Genes to Control Tracheal Tube Length
Epithelial tubes are the functional units of many organs, and proper tube geometry is crucial for organ function. Here, we characterize serrano (sano), a novel cytoplasmic protein that is apically enriched in several tube-forming epithelia in Drosophila, including the tracheal system. Loss of sano results in elongated tracheae, whereas Sano overexpression causes shortened tracheae with reduced apical boundaries. Sano overexpression during larval and pupal stages causes planar cell polarity (PCP) defects in several adult tissues. In Sano-overexpressing pupal wing cells, core PCP proteins are mislocalized and prehairs are misoriented; sano loss or overexpression in the eye disrupts ommatidial polarity and rotation. Importantly, Sano binds the PCP regulator Dishevelled (Dsh), and loss or ectopic expression of many known PCP proteins in the trachea gives rise to similar defects observed with loss or gain of sano, revealing a previously unrecognized role for PCP pathway components in tube size control
Expression of Wnt gene family and frizzled receptors in head and neck squamous cell carcinomas
[Abstract] Genes of the Wnt and Frizzled class, expressed in HNSCC tissue and cell lines, have an established role in cell morphogenesis and differentiation, and also they have oncogenic properties. We studied Wnt and Fz genes as potential tumor-associated markers in HNSCC by qPCR. Expression levels of Wnt and Fz genes in 22 unique frozen samples from HNSCC were measured. We also assessed possible correlation between the expression levels obtained in cancer samples in relation to clinicopathologic outcome. Wnt-1 was not expressed in the majority of the HNSCC studied, whereas Wnt-5A was the most strongly expressed by the malignant tumors. Wnt-10B expression levels were related with higher grade of undifferentiation. Related to Fz genes, Fz-5 showed more expression levels in no-affectation of regional lymph nodes. Kaplan–Meier survival analyses suggest a reduced time of survival for low and high expression of Wnt-7A and Fz-5 mRNA, respectively. qPCR demonstrated that HNSCC express Wnt and Fz members, and suggested that Wnt and Fz signaling is activated in HNSCC cells
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