Synthesizing a Global Net State from Synchronized Local Pieces

A traditional problem with state space analysis for concurrent systems has been the exponential explosion in the size of the state space relative to the size of the system. This explosion not only consumes an exponential amount of time in generating a state space, but an exponential amount of storage space as well. In this report we show a technique that attacks both the storage half and the time half of this problem. A synchronous net set is a collection of Petri nets that together model a system of concurrent processes. Rather than combine the process models into a large net for analysis, we keep the nets separate and allow special transitions to synchronize their respective executions implicitly. Analysis is done by computing and storing the state spaces for the individual nets, and then virtually combining the state spaces when a system-wide state query is performed. This approach saves a large amount of storage space over using a global net state space, and for certain conditions ..

Hyperdocuments as Automata: Verification of Trace-based Browsing Properties by Model Checking

As hypertext systems proliferate and as networks become more ubiquitous, an important problem is to determine how to provide hyperdocument interoperability. Instead of taking the approach of standardizing, and implementing, a large and complex set of browsing features gleaned from some "union" of existing systems, we present an approach that allows each document to encode its own browsing semantics in the links of the hyperdocument. Any implementation offering the "follow link" operation can then simulate the intent of the author. The method requires a mental shift in how a hyperdocument is viewed abstractly. Instead of treating the links of a document as defining a static directed graph, they are thought of as defining an abstract program, termed the links-automaton of the document. A branching temporal logic notation, termed HTL*, is introduced for specifying properties a document should exhibit during browsing. An automated program verification technique called model checking is ..

Hyperdocuments as Automata: Trace-based Browsing Property Verification

In many hypertext systems, meaningfully traversing a document depends on capabilities, features, and navigational aids that are part of the browser implementation. For example, if a reader browses to a node that has no out links, then backing up, or "warping" to the table of contents can allow the browsing session to continue. If hyperdocuments are to become interchangeable among hypertext systems, rather than being readable only on the systems from which they are authored, one obvious but complex approach is to try and standardize on (most likely, very many) browsing features and behaviors, forming some standard union of the capabilities of current major implementations. This approach molds (or perhaps restricts) future systems, since new browsing "features" must then be worked into such a standard. An alternate approach, used in this paper, is to de-emphasized browser features and emphasize inherent document structure with browsing semantics. An author should be able to create docume..

Methodological considerations on segmenting rhabdomyosarcoma with diffusion-weighted imaging—What can we do better?

Key points Strategies for segmenting sarcoma tumors vary widely throughout literature. Details of the segmentation strategy are often not reported. Including necrotic or cystic areas in the segmentation affects diffusion measurements. Varying the slice of a single-slice segmentation can drastically impact diffusion measurements

Quantitative diffusion-weighted MRI response assessment in rhabdomyosarcoma: an international retrospective study on behalf of the European paediatric Soft tissue sarcoma Study Group Imaging Committee

Objective To investigate the feasibility of diffusion-weighted magnetic resonance imaging (DW-MRI) as a predictive imaging marker after neoadjuvant chemotherapy in patients with rhabdomyosarcoma.Material and methods We performed a multicenter retrospective study including pediatric, adolescent and young adult patients with rhabdomyosarcoma, Intergroup Rhabdomyosarcoma Study group III/IV, treated according to the European paediatric Soft tissue sarcoma Study Group (EpSSG) RMS2005 or MTS2008 studies. DW-MRI was performed according to institutional protocols. We performed two-dimensional single-slice tumor delineation. Areas of necrosis or hemorrhage were delineated to be excluded in the primary analysis. Mean, median and 5th and 95th apparent diffusion coefficient (ADC) were extracted.Results Of 134 included patients, 82 had measurable tumor at diagnosis and response and DW-MRI scans of adequate quality and were included in the analysis. Technical heterogeneity in scan acquisition protocols and scanners was observed. Mean ADC at diagnosis was 1.1 (95% confidence interval [CI]: 1.1-1.2) (all ADC expressed in * 10(-3) mm(2)/s), versus 1.6 (1.5-1.6) at response assessment. The 5th percentile ADC was 0.8 (0.7-0.9) at diagnosis and 1.1 (1.0-1.2) at response. Absolute change in mean ADC after neoadjuvant chemotherapy was 0.4 (0.3-0.5). Exploratory analyses for association between ADC and clinical parameters showed a significant difference in mean ADC at diagnosis for alveolar versus embryonal histology. Landmark analysis at nine weeks after the date of diagnosis showed no significant association (hazard ratio 1.3 [0.6-3.2]) between the mean ADC change and event-free survival.Conclusion A significant change in the 5th percentile and the mean ADC after chemotherapy was observed. Strong heterogeneity was identified in DW-MRI acquisition protocols between centers and in individual patients.[GRAPHICS]