Graph- versus Vector-Based Analysis of a Consensus Protocol

The Paxos distributed consensus algorithm is a challenging case-study for standard, vector-based model checking techniques. Due to asynchronous communication, exhaustive analysis may generate very large state spaces already for small model instances. In this paper, we show the advantages of graph transformation as an alternative modelling technique. We model Paxos in a rich declarative transformation language, featuring (among other things) nested quantifiers, and we validate our model using the GROOVE model checker, a graph-based tool that exploits isomorphism as a natural way to prune the state space via symmetry reductions. We compare the results with those obtained by the standard model checker Spin on the basis of a vector-based encoding of the algorithm.Comment: In Proceedings GRAPHITE 2014, arXiv:1407.767

Model Checking Paxos in Spin

We present a formal model of a distributed consensus algorithm in the executable specification language Promela extended with a new type of guards, called counting guards, needed to implement transitions that depend on majority voting. Our formalization exploits abstractions that follow from reduction theorems applied to the specific case-study. We apply the model checker Spin to automatically validate finite instances of the model and to extract preconditions on the size of quorums used in the election phases of the protocol.Comment: In Proceedings GandALF 2014, arXiv:1408.556

On the Complexity of Parameterized Reachability in Reconfigurable Broadcast Networks

We investigate the impact of dynamic topology reconfiguration on the complexity of verification problems for models of protocols with broadcast communication. We first consider reachability of a configuration with a given set of control states and show that parameterized verification is decidable with polynomial time complexity. We then move to richer queries and show how the complexity changes when considering properties with negation or cardinality constraints

EXPERIMENTAL RESULTS AND TRANSIENT MODEL VALIDATION OF AN EXTERNALLY FIRED MICRO GAS TURBINE

ABSTRACT This paper presents the performance of the world's first Externally Fired micro Gas Turbine (EFmGT) demonstration plant based on micro gas turbine technology. The plant was designed by Ansaldo Ricerche (ARI) s.r.l. and the Thermochemical Power Group (TPG) of the Università di Genova, using the in-house TPG codes TEMP (Thermoeconomic Modular Program) and TRANSEO. The plant was based on a recuperated 80 kW micro gas turbine (Elliott TA-80R), which was integrated with the externally fired cycle at the ARI laboratory. The first goal of the plant construction was the demonstration of the EFmGT system at full and part-load operations, mainly from the control point of view. The performance obtained in the field can be improved in the near future using high-temperature heat exchangers and apt external combustors, which should allow the system to operate at the actual micro gas turbine inlet temperature (900-950 °C). This paper presents the plant layout and the control system employed for regulating the microturbine power and rotational speed. The experimental results obtained by the pilot plant in early 2004 are shown: the feasibility of such a plant configuration has been demonstrated, and the control system has successfully regulated the shaft speed in all the tests performed. Finally, the plant model in TRANSEO, which was formerly used to design the control system, is shown to accurately simulate the plant behavior both at steady-state and transient conditions

A Case of Neurotrophic Keratopathy Concomitant to Brain Metastasis

We report a case of a 63-year-old Caucasian female referred to the cornea service of Clinica Oculistica with a neurotrophic corneal ulcer, decreased corneal sensitivity, absent corneal reflex, and decreased lacrimation. The medical record review was relevant for mastectomy and adjuvant therapy for breast cancer complicated by pontocerebellar angle metastasis. Eye patching and application of antibiotic and vitamin ointments were prescribed at first, without a significant improvement. Thus, treatment with autologous serum was started. In about two weeks, the cornea recovered and visual acuity improved with a residual corneal scarring. Finally, we should mention that, in our case, the main cause of the neurotrophic corneal ulcer could be identified in the previous trigeminal damage at the pontocerebellar angle and trigeminal ganglion. Sensory nerves play an important regulatory role via neuro-mediators on corneal wound healing, as denervation may interfere with cellular metabolism and inhibit mitosis, leading to an epithelial defect even with no direct damage

Impact of different chemotherapy regimens on intestinal mucosal injury assessed with bedside ultrasound: a study in 213 AML patients

IntroductionNeutropenic enterocolitis (NEC) is a life-threatening complication reported in patients with acute myeloid leukemia (AML) following chemotherapy (CHT). Intensive induction and consolidation CHT may damage intestinal mucosa leading to a NEC episode (NECe). NEC reported mortality may be up to 30-60%. Early US-guided bed-side diagnosis and prompt treatment may substantially improve the survival. An emerging worldwide concern is the intestinal colonization by multi-drug-resistant bacteria especially when patients are exposed to chemotherapy regimens potentially correlated to mucosal damage. MethodsIn our study we prospectively enrolled all AML patients admitted in our leukemia unit to receive intensive induction and consolidation chemotherapy and experiencing chemotherapy-induced-neutropenia (CHTN). Results and discussionOverall, we enrolled N=213 patients from 2007 to March 2023. We recorded N=465 CHTN, and N=42 NECe (9.0% incidence). The aim of our study was to assess which chemotherapy regimens are more associated with NEC. We found that ALM1310, followed by 7 + 3 (daunorubicin), 7 + 3 (idarubicin), 5 + 3 + 3 (cytarabine, etoposide, idarubicin), and AML1310 (consolidation) were associated with a statistically higher incidence of NEC. We did not detect NEC episodes in patients treated with CPX-351, 5 + 2 (cytarabine, idarubicine), and high-dose cytarabine. Thus, we found that cytarabine could determine mucosal damage when associated with an anthracycline but not if delivered either alone or as dual-drug liposomal encapsulation of daunorubicin/cytarabine. We also describe NEC mortality, symptoms at diagnosis, intestinal sites involvement, and prognostic significance of bowel wall thickening

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection