Uniform Labeled Transition Systems for Nondeterministic, Probabilistic, and Stochastic Process Calculi

Labeled transition systems are typically used to represent the behavior of nondeterministic processes, with labeled transitions defining a one-step state to-state reachability relation. This model has been recently made more general by modifying the transition relation in such a way that it associates with any source state and transition label a reachability distribution, i.e., a function mapping each possible target state to a value of some domain that expresses the degree of one-step reachability of that target state. In this extended abstract, we show how the resulting model, called ULTraS from Uniform Labeled Transition System, can be naturally used to give semantics to a fully nondeterministic, a fully probabilistic, and a fully stochastic variant of a CSP-like process language.Comment: In Proceedings PACO 2011, arXiv:1108.145

The Spectrum of Strong Behavioral Equivalences for Nondeterministic and Probabilistic Processes

We present a spectrum of trace-based, testing, and bisimulation equivalences for nondeterministic and probabilistic processes whose activities are all observable. For every equivalence under study, we examine the discriminating power of three variants stemming from three approaches that differ for the way probabilities of events are compared when nondeterministic choices are resolved via deterministic schedulers. We show that the first approach - which compares two resolutions relatively to the probability distributions of all considered events - results in a fragment of the spectrum compatible with the spectrum of behavioral equivalences for fully probabilistic processes. In contrast, the second approach - which compares the probabilities of the events of a resolution with the probabilities of the same events in possibly different resolutions - gives rise to another fragment composed of coarser equivalences that exhibits several analogies with the spectrum of behavioral equivalences for fully nondeterministic processes. Finally, the third approach - which only compares the extremal probabilities of each event stemming from the different resolutions - yields even coarser equivalences that, however, give rise to a hierarchy similar to that stemming from the second approach.Comment: In Proceedings QAPL 2013, arXiv:1306.241

A uniform framework for modelling nondeterministic, probabilistic, stochastic, or mixed processes and their behavioral equivalences

Labeled transition systems are typically used as behavioral models of concurrent processes, and the labeled transitions define the a one-step state-to-state reachability relation. This model can be made generalized by modifying the transition relation to associate a state reachability distribution, rather than a single target state, with any pair of source state and transition label. The state reachability distribution becomes a function mapping each possible target state to a value that expresses the degree of one-step reachability of that state. Values are taken from a preordered set equipped with a minimum that denotes unreachability. By selecting suitable preordered sets, the resulting model, called ULTraS from Uniform Labeled Transition System, can be specialized to capture well-known models of fully nondeterministic processes (LTS), fully probabilistic processes (ADTMC), fully stochastic processes (ACTMC), and of nondeterministic and probabilistic (MDP) or nondeterministic and stochastic (CTMDP) processes. This uniform treatment of different behavioral models extends to behavioral equivalences. These can be defined on ULTraS by relying on appropriate measure functions that expresses the degree of reachability of a set of states when performing single-step or multi-step computations. It is shown that the specializations of bisimulation, trace, and testing equivalences for the different classes of ULTraS coincide with the behavioral equivalences defined in the literature over traditional models

Revisiting bisimilarity and its modal logic for nondeterministic and probabilistic processes

We consider PML, the probabilistic version of Hennessy-Milner logic introduced by Larsen and Skou to characterize bisimilarity over probabilistic processes without internal nondeterminism.We provide two different interpretations for PML by considering nondeterministic and probabilistic processes as models, and we exhibit two new bisimulation-based equivalences that are in full agreement with those interpretations. Our new equivalences include as coarsest congruences the two bisimilarities for nondeterministic and probabilistic processes proposed by Segala and Lynch. The latter equivalences are instead in agreement with two versions of Hennessy-Milner logic extended with an additional probabilistic operator interpreted over state distributions rather than over individual states. Thus, our new interpretations of PML and the corresponding new bisimilarities offer a uniform framework for reasoning on processes that are purely nondeterministic or reactive probabilistic or are mixing nondeterminism and probability in an alternating/non-alternating way

LONG-TERM INTRAOCULAR PRESSURE AFTER UNCOMPLICATED PARS PLANA VITRECTOMY FOR IDIOPATHIC EPIRETINAL MEMBRANE

\u2019Purrpose: To investigate long-term intraocular pressure trends after uncomplicated pars plana vitrectomy for idiopathic epiretinal membrane. Methods: Three hundred and sixty-eight eyes of 368 consecutive patients were enrolled. Changes in intraocular pressure 1, 3, 6, and 12 months after surgery and during the fi nal follow-up visit were evaluated in vitrectomized eyes and nonvitrectomized fellow eyes. Results: The median follow-up period was 36 months (range 12 \u2013 92 months). Longitudinal data analysis evidenced a 2.5-mmHg (2.2 mmHg; 2.7 mmHg, 95% con fi dence interval) statis- tically signi fi cant difference in intraocular pressure 30 days after surgery between treated and fellow untreated eyes, gradually recovering to a not signi fi cant 0.2-mmHg ( 2 0.1 mmHg; 0.4 mmHg, 95% con fi dence interval) difference within 26 months. The incidence of late-onset ocular hypertension was 5.7% (21 over 347, 2%; 12%, 95% con fi dence interval) without difference between the treated eyes and the group control. No signi fi cant difference in the incidence of late-onset ocular hypertension and sex, lens status, or gauge of vitrectomy instru- ments was detected. Only patient \u2019 sagewassigni fi cantly higher (mean difference 4.2 years; 0.1 \u2013 8.0 years, Monte Carlo, 95% con fi dence interval) in those who de veloped late-onset ocular hypertension in the vitrectomized eye. Conclusion: Uncomplicated pars plana vitrectomy for idiopathic epiretinal membrane seems not to increase the risk of late-onset ocular hypertension or open-angle glaucoma development.

Impact of Epiretinal Membrane on Optical Coherence Tomography Tools Used for Monitoring Glaucoma

Background: Retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) measurements can be influenced by many factors including the presence of concomitant retinal diseases. The aim of this study it to assess the impact of epiretinal membrane (ERM) on RNFL and GCL assessment using optical coherence tomography (OCT). Methods: GCL, peripapillary RNFL (pRNFL), and Bruch's Membrane Opening Minimum Rim Width (BMO-MRW) thicknesses were analysed using an SD-OCT (Spectralis OCT) in eyes with idiopathic ERM and compared with a control group. Results: 161 eyes were included, 73 eyes in the control group and 88 eyes with idiopathic ERM. The pRNFL analysis revealed a statistically significant difference between the two groups in overall and temporal sector thicknesses. For GCL thickness report, the percentage of scans in which the GCL was erroneously segmented by automatic segmentation was assessed for each eye. A statistically significant difference was found in all sectors (p < 0.001), with the exception of external nasal sector. A statistically significant difference (p < 0.001) in the GCL total volume report was found in ERM group compared to the control group. For MRW at BMO analysis, there was no statistically significant difference in MRW thickness in any sector. Conclusion: In eyes with ERM, the GCL and pRNFL analysis seemed affected by the morphological retinal layers' modification. MRW-BMO did not appear to be directly affected by the presence of ERM

Video-Assisted Thyroidectomy for Papillary Thyroid Carcinoma

Background. The results of video-assisted thyroidectomy (VAT) were evaluated in a large series of patients with papillary thyroid carcinoma (PTC), especially in terms of completeness of the surgical resection and short-to-medium term recurrence. Methods. The medical records of all patients who underwent video-assisted thyroidectomy for PTC between June 1998 and May 2009 were reviewed. Results. Three hundred fifty-nine patients were included. One hundred twenty-six patients underwent concomitant central neck node removal. Final histology showed 285 pT1, 26 pT2, and 48 pT3 PTC. Lymph node metastases were found in 27 cases. Follow-up was completed in 315 patients. Mean postoperative serum thyroglobulin level off levothyroxine was 5.4 ng/mL. Post operative ultrasonography showed no residual thyroid tissue in all the patients. Mean post-operative 131I uptake was 1.7%. One patient developed lateral neck recurrence. No other recurrence was observed

Bacterioplankton diversity and distribution in relation to phytoplankton community structure in the Ross Sea surface waters

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cordone, A., D’Errico, G., Magliulo, M., Bolinesi, F., Selci, M., Basili, M., de Marco, R., Saggiomo, M., Rivaro, P., Giovannelli, D., & Mangoni, O. Bacterioplankton diversity and distribution in relation to phytoplankton community structure in the Ross Sea surface waters. Frontiers in Microbiology, 13, (2022): 722900, https://doi.org/10.3389/fmicb.2022.722900.Primary productivity in the Ross Sea region is characterized by intense phytoplankton blooms whose temporal and spatial distribution are driven by changes in environmental conditions as well as interactions with the bacterioplankton community. However, the number of studies reporting the simultaneous diversity of the phytoplankton and bacterioplankton in Antarctic waters are limited. Here, we report data on the bacterial diversity in relation to phytoplankton community structure in the surface waters of the Ross Sea during the Austral summer 2017. Our results show partially overlapping bacterioplankton communities between the stations located in the Terra Nova Bay (TNB) coastal waters and the Ross Sea Open Waters (RSOWs), with a dominance of members belonging to the bacterial phyla Bacteroidetes and Proteobacteria. In the TNB coastal area, microbial communities were characterized by a higher abundance of sequences related to heterotrophic bacterial genera such as Polaribacter spp., together with higher phytoplankton biomass and higher relative abundance of diatoms. On the contrary, the phytoplankton biomass in the RSOW were lower, with relatively higher contribution of haptophytes and a higher abundance of sequences related to oligotrophic and mixothrophic bacterial groups like the Oligotrophic Marine Gammaproteobacteria (OMG) group and SAR11. We show that the rate of diversity change between the two locations is influenced by both abiotic (salinity and the nitrogen to phosphorus ratio) and biotic (phytoplankton community structure) factors. Our data provide new insight into the coexistence of the bacterioplankton and phytoplankton in Antarctic waters, suggesting that specific rather than random interaction contribute to the organic matter cycling in the Southern Ocean.Samples were collected in the framework of Plankton biodiversity and functioning of the Ross Sea ecosystems in a changing Southern Ocean [P-ROSE – (PNRA16_00239)], and CDW Effects on glacial mElting and on Bulk of Fe in the Western Ross sea [CELEBeR – (PNRA16_00207)] projects – Italian National Antarctic Program – funded by the Ministry of Education, University and Research (MIUR), awarded to OM and PR, respectively. MM was supported by an Earth-Life Science Institute (Tokyo, Japan) visiting fellowship. This work was partially supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948972) to DG