Coded Emulation of Shared Atomic Memory for Message Passing Architectures

This paper considers the communication and storage costs of emulating atomic (linearizable) read/write shared memory in distributed message-passing systems. We analyze the costs of previously-proposed algorithms by Attiya, Bar-Noy, and Dolev (the ABD algorithm) and by Fan and Lynch (the LDR algorithm), and develop new coding-based algorithms that significantly reduce these costs. The paper contains three main contributions: (1) We present a new shared-memory algorithm that we call CAS, for Coded Atomic Storage. This algorithm uses erasure coding methods. (2) In a storage system with N servers that is resilient to f server failures, we show that the communication costs for the ABD and LDR algorithms, measured in terms of number of object values, are both at least f + 1, whereas the communication cost for CAS is N/(N-2f). (3) We also explicitly quantify the storage costs of the ABD, LDR, and CAS algorithms. The storage cost of the ABD algorithm, measured in terms of number of object values, is N; whereas the storage costs of the LDR and CAS algorithms are both unbounded. We present a modification of the CAS algorithm based on the idea of garbage collection. The modified version of CAS has a storage cost of (d + 1) N/(N-2f), where d in an upper bound on the number of operations that are concurrent with a read operation. Thus, if d is sufficiently small, the storage cost of CAS is lower than those of both the ABD and LDR algorithms

A Coded Shared Atomic Memory Algorithm for Message Passing Architectures

This paper considers the communication and storage costs of emulating atomic (linearizable) multi-writer multi-reader shared memory in distributed message-passing systems. The paper contains three main contributions: (1) We present a atomic shared-memory emulation algorithm that we call Coded Atomic Storage (CAS). This algorithm uses erasure coding methods. In a storage system with 'N' servers that is resilient to 'f' server failures, we show that the communication cost of CAS is N/(N-2f) . The storage cost of CAS is unbounded. (2) We present a modification of the CAS algorithm known as CAS with Garbage Collection (CASGC). The CASGC algorithm is parametrized by an integer 'd' and has a bounded storage cost. We show that in every execution where the number of write operations that are concurrent with a read operation is no bigger than 'd', the CASGC algorithm with parameter 'd' satisfies atomicity and liveness. We explicitly characterize the storage cost of CASGC, and show that it has the same communication cost as CASGC. (3) We describe an algorithm known as the Communication Cost Optimal Atomic Storage (CCOAS) algorithm that achieves a smaller communication cost than CAS and CASGC. In particular, CCOAS incurs read and write communication costs of N/(N-f) measured in terms of number of object values. We also discuss drawbacks of CCOAS as compared with CAS and CASGC

Implementation of a closed-loop structural control system using wireless sensor networks

Wireless sensor networks have rapidly matured in recent years to offer data acquisition capabilities on par with those of traditional tethered data acquisition systems. Entire structural monitoring systems assembled from wireless sensors have proven to be low cost, easy to install, and accurate. However, the functionality of wireless sensors can be further extended to include actuation capabilities. Wireless sensors capable of actuating a structure could serve as building blocks of future generations of structural control systems. In this study, a wireless sensor prototype capable of data acquisition, computational analysis and actuation is proposed for use in a real-time structural control system. The performance of a wireless control system is illustrated using a full-scale structure controlled by a semi-active magnetorheological (MR) damper and a network of wireless sensors. One wireless sensor designated as a controller automates the task of collecting state data, calculating control forces, and issuing commands to the MR damper, all in real time. Additional wireless sensors are installed to measure the acceleration and velocity response of each system degree of freedom. Base motion is applied to the structure to simulate seismic excitations while the wireless control system mitigates inter-storey drift response of the structure. An optimal linear quadratic regulation solution is formulated for embedment within the computational cores of the wireless sensors. Copyright © 2007 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/60230/1/214_ftp.pd

Zn Diffusion and α-Fe(Zn) Layer Growth During Annealing of Zn-Coated B Steel

Direct hot press forming of Zn-coated 22MnB5 steels is impeded by micro-cracks that occur in the substrate due to the presence of Zn during the forming process. A study was therefore undertaken to quantify concentration of Zn across the α-Fe(Zn) coating and on grain boundaries in the α-Fe(Zn) layer and the underlying γ-Fe(Zn) substrate after isothermal annealing of Zn-coated 22MnB5 at 1173 K (900 °C) and to link the Zn distribution to the amount and type of micro-cracks observed in deformed samples. Finite difference model was developed to describe Zn diffusion and the growth of the α-Fe(Zn) layer. The penetration of Zn into the γ-Fe(Zn) substrate after 600 seconds annealing at 1173 K (900 °C) through bulk diffusion is estimated to be 3 μm, and the diffusion depth of Zn on the γ-Fe(Zn) grain boundaries is estimated to be 6 μm, which is significantly shorter than the maximum length (15 to 50 μm) of the micro-cracks formed in the severely stressed conditions, indicating that the Zn diffusion into the γ-Fe(Zn) from the α-Fe(Zn) during annealing is not correlated to the depth of micro-cracks. On the other hand, the maximum amount of Zn present in α-Fe(Zn) layer decreases with annealing time as the layer grows and Zn oxidizes, and the amount of Zn-enriched areas inside the α-Fe(Zn) layer is reduced leading to reduced length of cracking. Solid-Metal-Induced Embrittlement mechanism is proposed to explain the benefit of extended annealing on reduced depth of micro-crack penetration into the γ-Fe(Zn) substrate

How is research publishing going to progress in the next 20 years?:Transcription of Session for Editors, Associate Editors, Publishers and Others with an Interest in Scientific Publishing Held at IADR Meeting In Seattle on Wednesday, 20 March 2013

On March 20th 2013, a one‐hour session for E ditors, A ssociate Editors, P ublishers and others with an interest in scientific publishing was held at the IADR I nternational S ession in Seattle. Organised by K enneth E aton and C hris L ynch ( C hair and S ecretary, respectively, of the B ritish D ental E ditors F orum), the meeting sought to bring together leading international experts in dental publishing, as well as authors, reviewers and students engaged in research. The meeting was an overwhelming success, with more than 100 attendees. A panel involving four leading dental editors led a discussion on anticipated developments in publishing dental research with much involvement and contribution from audience members. This was the third such meeting held at the IADR for E ditors, A ssociate E ditors, P ublishers and others with an interest in scientific publishing. A follow up session will take place in C ape T own on 25 J une 2014 as part of the annual IADR meeting. The transcript of the meeting is reproduced in this article. Where possible speakers are identified by name. At the first time of mention their role/ position is also stated, thereafter only their name appears. We are grateful to S tephen H ancocks Ltd for their generous sponsorship of this event. For those who were not able to attend the authors hope this article gives a flavour of the discussions and will encourage colleagues to attend future events. Involvement is open to E ditors, A ssociate E ditors, Publishers and others with an interest in scientific publishing. It is a very open group and all those with an interest will be welcome to join in.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106931/1/eje12089.pd

Arachidonic acid metabolism is altered in sarcoid alveolar macrophages,

Macrophages produce various arachidonic acid (AA) metabolites which may either enhance or suppress inflammatory processes. We investigated AA metabolite production by alveolar macrophages (AMs) from 11 patients with pulmonary sarcoidosis and 9 normal volunteers. We assessed the production of both cyclooxygenase products (prostaglandin (PG) E2, thromboxane B2 (TXB2), PGF2[alpha], and 6-keto-PGF1[alpha]) and lipoxygenase products (leukotrienes (LT) and hydroxyeicosatetraenoic acids (HETEs)) in AM cultures. We found that sarcoid AMs produced less PGE2, TXB2, 6-keto-PGF1[alpha], and HETEs in both the unstimulated and the calcium ionophore-stimulated states compared with normal AMs. Sarcoid AMs also produced less PGF2[alpha] and LTs in the unstimulated state after 1 hr of incubation, but following calcium ionophore stimulation, these differences did not achieve statistical significance. We conclude that sarcoid AMs have a reduced capacity to produce AA metabolites compared with that of normal AMs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26855/1/0000420.pd

Startle disease mutations reduce the agonist sensitivity of the human inhibitory glycine receptor

The receptor for the inhibitory neurotransmitter glycine is a member of the ligand gated ion channel recep tor superfamily. Point mutations in the gene encoding the alpha 1 subunit of the glycine receptor channel complex (GlyR) have recently been identified in pedigrees with the autosomal dominant neurological disorder, startle disease (hyperekplexia). These mutations result in the substitution of leucine or glutamine for arginine 271. This charged residue is located near the ion channel region and is predicted to affect chloride permeation through the GlyR. We found little evidence for this role from the anion/cation selectivity and lack of pronounced rectification of currents flowing through recombinant human alpha 1 subunit GlyRs containing the startle disease mutations. We reveal, however, that the startle disease mutations profoundly disrupt GlyR func tion by causing 230-410-fold decreases in the sensitivity of receptor currents activated by the agonist glycine. Additionally, we report corresponding 56- and 120-fold reductions in the apparent binding affinity (K-i) of glycine to the mutant GlyRs, but no change in the binding affinity of the competitive antagonist, strychnine. Thus, startle disease reduces the efficacy of glycinergic inhibitory neurotransmission by producing GlyRs with diminished agonist responsiveness. Our results show that startle disease mutations define a novel receptor activation site

Plant communities affect arbuscular mycorrhizal fungal diversity and community composition in grassland microcosms

The diversity of arbuscular mycorrhizal (AM) fungi was investigated in an unfertilized limestone grassland soil supporting different synthesized vascular plant assemblages that had developed for 3 yr. The experimental treatments comprised: bare soil; monocultures of the nonmycotrophic sedge Carex flacca; monocultures of the mycotrophic grass Festuca ovina; and a species-rich mixture of four forbs, four grasses and four sedges. The diversity of AM fungi was analysed in roots of Plantago lanceolata bioassay seedlings using terminal-restriction fragment length polymorphism (T-RFLP). The extent of AM colonization, shoot biomass and nitrogen and phosphorus concentrations were also measured. The AM diversity was affected significantly by the floristic composition of the microcosms and shoot phosphorus concentration was positively correlated with AM diversity. The diversity of AM fungi in P. lanceolata decreased in the order: bare soil > C. flacca > 12 species > F. ovina. The unexpectedly high diversity in the bare soil and sedge monoculture likely reflects differences in the modes of colonization and sources of inoculum in these treatments compared with the assemblages containing established AM-compatible plants

Impact of sarcopenia on treatment tolerance in United States veterans with diffuse large B‐cell lymphoma treated with CHOP‐based chemotherapy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134181/1/ajh24465_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134181/2/ajh24465.pd