Home  About us  Contact
 

Sequential Model (sequential + model)

Distribution by Scientific Domains
Medical Sciences33%

Selected Abstracts

Sequential model of phage PRD1 DNA delivery: active involvement of the viral membrane

MOLECULAR MICROBIOLOGY, Issue 5 2002
A. Marika Grahn
Summary DNA translocation across the barriers of recipient cells is not well understood. Viral DNA delivery mechanisms offer an opportunity to obtain useful information in systems in which the process can be arrested to a number of stages. PRD1 is an icosahedral double-stranded (ds)DNA bacterial virus with an internal membrane. It is an atypical dsDNA phage, as any of the vertex spikes can be used for receptor recognition. In this report, we dissect the PRD1 DNA entry into a number of steps: (i) outer membrane (OM) penetration; (ii) peptidoglycan digestion; (iii) cytoplasmic membrane (CM) penetration; and (iv) DNA translocation. We present a model for PRD1 DNA entry proposing that the initial stage of entry is powered by the pressure build-up during DNA packaging. The viral protein P11 is shown to function as the first DNA delivery protein needed to penetrate the OM. We also report a DNA translocation machinery composed of at least three viral integral membrane proteins, P14, P18 and P32. [source]

The effect of uncontrolled concurrency on model checking

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 12 2008
Donna M. Carter
Abstract Correctness of concurrent software is usually checked by techniques such as peer code reviews or code walkthroughs and testing. These techniques, however, are subject to human error, and thus do not achieve an in-depth verification of correctness. Model-checking techniques, which can systematically identify and verify every state that a system can enter, are a powerful alternative method for verifying concurrent systems. However, the usefulness of model checking is limited because the number of states for concurrent models grows exponentially with the number of processes in the system. This is often referred to as the ,state explosion problem.' Some processes are a central part of the software operation and must be included in the model. However, we have found that some exponential complexity results due to uncontrolled concurrency introduced by the programmer rather than due to the intrinsic characteristics of the software being modeled. We have performed tests on multimedia synchronization to show the effect of abstraction as well as uncontrolled concurrency using the Promela/SPIN model checker. We begin with a sequential model not expected to have exponential complexity but that results in exponential complexity. In this paper, we provide alternative designs and explain how uncontrolled concurrency can be removed from the code. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Physiotherapists in Balint group training

PHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 2 2000
Dr Madeleine Abrandt Dahlgren
Abstract Background and Purpose Balint group training (BGT) is a method widely used for enhancing understanding of the relationship and communication between health professionals and their patients. Participants meet in small groups, on a regular basis, with a tutor to discuss their experiences of problem cases. The method was originally developed in the 1950s for enhancing understanding of the doctor,patient relationship. Few studies have focused on BGT and physiotherapists. The aim of the present study was to describe and analyse physiotherapists' experiences of participation in BGT as a means of learning and understanding the physiotherapist,patient relationship. Method Semi-structured, in-depth interviews were conducted with three physiotherapists working in private practice, all participating in BGT. The intervews were transcribed and subjected to a qualitative analysis. Results The results are presented in a sequential model, featuring eight themes in which the physiotherapists' experiences of the training process are portrayed. Conclusions The results suggest that BGT and sharing the experiences of others may be considered a way of enhancing understanding of the patient encounter in clinical practice, possibly to the benefit of physiotherapists and their patients. Copyright © 2000 Whurr Publishers Ltd. [source]

Sequential innovation, patents, and imitation

THE RAND JOURNAL OF ECONOMICS, Issue 4 2009
James Bessen
We argue that when innovation is "sequential" (so that each successive invention builds in an essential way on its predecessors) and "complementary" (so that each potential innovator takes a different research line), patent protection is not as useful for encouraging innovation as in a static setting. Indeed, society and even inventors themselves may be better off without such protection. Furthermore, an inventor's prospective profit may actually be enhanced by competition and imitation. Our sequential model of innovation appears to explain evidence from a natural experiment in the software industry. [source]

Formation of submarginal and proglacial end moraines: implications of ice-flow mechanism during the 1963,64 surge of Brúarjökull, Iceland

BOREAS, Issue 3 2009
ÍVAR ÖRN BENEDIKTSSON
The morphology, sedimentology and architecture of an end moraine formed by a ,9 km surge of Brúarjökull in 1963,64 are described and related to ice-marginal conditions at surge termination. Field observations and accurate mapping using digital elevation models and high-resolution aerial photographs recorded at surge termination and after the surge show that commonly the surge end moraine was positioned underneath the glacier snout by the termination of the surge. Ground-penetrating radar profiles and sedimentological data reveal 4,5 m thick deformed sediments consisting of a top layer of till overlying gravel and fine-grained sediments, and structural geological investigations show that the end moraine is dominated by thrust sheets. A sequential model explaining the formation of submarginal end moraines is proposed. The hydraulic conductivity of the bed had a major influence on the subglacial drainage efficiency and associated porewater pressure at the end of the surge, thereby affecting the rates of subglacial deformation. High porewater pressure in the till decreased its shear strength and raised its strain rate, while low porewater pressure in the underlying gravel had the opposite effect, such that the gravel deformed more slowly than the till. The principal velocity component was therefore located within the till, allowing the glacier to override the gravel thrust sheets that constitute the end moraine. The model suggests that the processes responsible for the formation of submarginal end moraines are different from those operating during the formation of proglacial end moraines. [source]

Are dysautonomic and sensory symptoms present in early Parkinson's disease?

ACTA NEUROLOGICA SCANDINAVICA, Issue 2010
O.-B. Tysnes
Tysnes O-B, Müller B, Larsen JP. Are dysautonomic and sensory symptoms present in early Parkinson's disease? Acta Neurol Scand: 2010: 122 (Suppl. 190): 72,77. © 2010 John Wiley & Sons A/S. Parkinson's disease (PD) occurs with an annual incidence of 13/100.000, is slightly more frequent in men and is characterized by the motor symptoms tremor, rigidity, bradykinesia and postural instability. In addition, non-motor symptoms have been increasingly connected to the disease although already described in James Parkinson's ,Essay on the shaking palsy' from 1817. The motor symptoms in PD are related to the degeneration of dopaminergic cells in the substantia nigra (SN). These symptoms respond well to dopaminergic substitution. It is much more unclear whether non-motor symptoms like dysautonomia, insomnia, day-time sleepiness, fatigue, pain and neuropsychiatric symptoms respond to levodopa. Autonomic symptoms include dizziness because of orthostatic hypotension, constipation, nausea, voiding symptoms and increased sweating. Such symptoms as well as sensory symptoms like hyposmia and pain are very frequently reported in PD and seem to occur early in the disease process. Braak proposed a sequential model of neuropathology in PD starting with affection of the olfactory bulb and the autonomic innervation of the heart and gut. Affection of SN is seen from Braak stage 3, and limbic and cortical structures are affected in the later stages of the disease. Currently, the evidence for sensory and autonomic involvement in PD is reviewed with special focus on the early phase of the disease. [source]