A Domain-Specific Language for Incremental and Modular Design of Large-Scale Verifiably-Safe Flow Networks (Preliminary Report)

We define a domain-specific language (DSL) to inductively assemble flow networks from small networks or modules to produce arbitrarily large ones, with interchangeable functionally-equivalent parts. Our small networks or modules are "small" only as the building blocks in this inductive definition (there is no limit on their size). Associated with our DSL is a type theory, a system of formal annotations to express desirable properties of flow networks together with rules that enforce them as invariants across their interfaces, i.e, the rules guarantee the properties are preserved as we build larger networks from smaller ones. A prerequisite for a type theory is a formal semantics, i.e, a rigorous definition of the entities that qualify as feasible flows through the networks, possibly restricted to satisfy additional efficiency or safety requirements. This can be carried out in one of two ways, as a denotational semantics or as an operational (or reduction) semantics; we choose the first in preference to the second, partly to avoid exponential-growth rewriting in the operational approach. We set up a typing system and prove its soundness for our DSL.Comment: In Proceedings DSL 2011, arXiv:1109.032

Shared Nearest Neighbors Approach and Interactive Browser for Network Analysis of a Comprehensive Non-Small-Cell Lung Cancer Data Set

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A comparative view of glacial and periglacial landforms on Earth and Mars

This paper emphasizes the importance of using terrestrial analogues to improve our understanding of the role of ice on Mars through its associated landforms. We discuss terrestrial regions and techniques that can help understand Martian icy environments, and highlight the necessity to explore the Martian cryosphere as the next natural step

The IEEE 802.17 Media Access Protocol for High-Speed Metropolitan-Area Resilient Packet Rings

The Resilient Packet Ring (RPR) IEEE 802.17 standard is under development as a new high-speed technology for metropolitan backbone networks. A key performance objective of RPR is to simultaneously achieve high utilization, spatial reuse, and fairness, an objective not achieved by current technologies such as SONET and Gigabit Ethernet nor by legacy ring technologies such as FDDI. The core technical challenge for RPR is the design of a fairness algorithm that dynamically throttles traffic to achieve these properties. The difficulty is in the distributed nature of the problem, that upstream ring nodes must inject traffic at a rate according to congestion and fairness criteria downstream. This article provides an overview of the RPR protocol with a focus on medium access and fairness

Design, Analysis, and Implementation of DVSR: A Fair, High Performance Protocol for Packet Rings

The Resilient Packet Ring (RPR) IEEE 802.17 standard is a new technology for high-speed backbone metropolitan area networks. A key performance objective of RPR is to simultaneously achieve high utilization, spatial reuse, and fairness, an objective not achieved by current technologies such as SONET and Gigabit Ethernet nor by legacy ring technologies such as FDDI. The core technical challenge for RPR is the design of a bandwidth allocation algorithm that dynamically achieves these three properties. The difficulty is in the distributed nature of the problem, that upstream ring nodes must inject traffic at a rate according to congestion and fairness criteria downstream. Unfortunately, we show that under unbalanced and constant-rate traffic inputs, the RPR fairness algorithm suffers from severe and permanent oscillations spanning nearly the entire range of the link capacity. Such oscillations hinder spatial reuse, decrease throughput, and increase delay jitter. In this paper, we introduce a new dynamic bandwidth allocation algorithm called Distributed Virtualtime Scheduling in Rings (DVSR). The key idea is for nodes to compute a simple lower bound of temporally and spatially aggregated virtual time using per-ingress counters of packet (byte) arrivals. We show that with this information propagated along the ring, each node can remotely approximate the ideal fair rate for its own traffic at each downstream link. Hence, DVSR flows rapidly converge to their ring-wide fair rates while maximizing spatial reuse. To evaluate DVSR, we develop an idealized fairness reference model and bound the deviation in service between DVSR and the reference model, thereby bounding the unfairness. With simulations, we find that compared to current techniques, DVSR's convergence times are an orde..

Alpha-2-adrenoceptor control of cortisol and ACTH in normal volunteers: preliminary open trial of the effects of acute and chronic idazoxan.

To examine the role of alpha 2-adrenoceptors in the control of cortisol and ACTH, hormone responses to the selective alpha 2-antagonist idazoxan were studied in 12 normal volunteers. Plasma cortisol and ACTH were measured from 0930h-1230h on three occasions: before, on the 1st day, and on the 22nd day of an open treatment trial with idazoxan 40 mg administered three times per day. Compared with pretreatment cortisol levels, acute but not chronic idazoxan treatment attenuated the normal diurnal fall in plasma cortisol. Plasma ACTH concentrations were not altered by either dose of idazoxan. The attenuation of the diurnal fall in cortisol after acute idazoxan may be mediated through increased central availability of norepinephrine, and is similar to responses after high doses of the less selective alpha 2-antagonist yohimbine. Activity of central noradrenergic neurons appears to be reduced or normalized by chronic idazoxan, indicated by restoration of the normal diurnal fall in cortisol