Petri net-based modelling of human-automation conflicts in aviation.

Analyses of aviation safety reports reveal that human-machine conflicts induced by poor automation design are remarkable precursors of accidents. A review of different crew-automation conflicting scenarios shows that they have a common denominator: the autopilot behaviour interferes with the pilot's goal regarding the flight guidance via 'hidden' mode transitions. Considering both the human operator and the machine (i.e. the autopilot or the decision functions) as agents, we propose a Petri net model of those conflicting interactions, which allows them to be detected as deadlocks in the Petri net. In order to test our Petri net model, we designed an autoflight system that was formally analysed to detect conflicting situations. We identified three conflicting situations that were integrated in an experimental scenario in a flight simulator with 10 general aviation pilots. The results showed that the conflicts that we had a-priori identified as critical had impacted the pilots' performance. Indeed, the first conflict remained unnoticed by eight participants and led to a potential collision with another aircraft. The second conflict was detected by all the participants but three of them did not manage the situation correctly. The last conflict was also detected by all the participants but provoked typical automation surprise situation as only one declared that he had understood the autopilot behaviour. These behavioural results are discussed in terms of workload and number of fired 'hidden' transitions. Eventually, this study reveals that both formal and experimental approaches are complementary to identify and assess the criticality of human-automation conflicts. Practitioner Summary: We propose a Petri net model of human-automation conflicts. An experiment was conducted with general aviation pilots performing a scenario involving three conflicting situations to test the soundness of our formal approach. This study reveals that both formal and experimental approaches are complementary to identify and assess the criticality conflicts.

Multimodal therapy of word retrieval disorder due to phonological encoding dysfunction.

OBJECTIVE: To determine whether phonological multimodal therapy can improve naming and communication in a patient showing a lexical phonological naming disorder. This study employed oral and written learning tasks, using an error reduction procedure. METHODS: A single-case design computer-assisted treatment was used with a 52 year-old woman with fluent aphasia consecutive to a cerebral infarction. The cognitive analysis of her word retrieval disorder exhibited a phonological encoding dysfunction. Thus, a phonological procedure was designed addressing the output phonological lexicon using computer analysis of spoken and written words. The effects were tested for trained words, generalization to untrained words, maintenance and specificity. Transfer of improvement to daily life was also assessed. OUTCOMES AND RESULTS: After therapy, the verbal naming of both trained and untrained words was improved at p < 0.001. The improvement was still maintained after 3 months without therapy. This treatment was specific since the word dictation task did not change. Communication in daily life was improved at p < 0.05. CONCLUSIONS: This study of a patient with word retrieval disorder due to phonological encoding dysfunction demonstrated the effectiveness of a phonological and multimodal therapeutic treatment.

Clinical outcome after a totally implantable venous access port-related infection in cancer patients: a prospective study and review of the literature.

Morbidity and mortality after a totally implantable venous access port (TIVAP)-related infection in oncology patients have rarely been studied. We conducted this study to assess the incidence and factors associated with the following outcome endpoints: severe sepsis or septic shock at presentation, cancellation of antineoplastic chemotherapy, and mortality at week 12. We conducted a prospective single-center observational study including all adult patients with solid cancer who experienced a TIVAP-related infection between February 1, 2009, and October 31, 2010. Patients were prospectively followed for 12 weeks. Among 1728 patients receiving antineoplastic chemotherapy during the inclusion time, 72 had an episode of TIVAP-related infection (4.2%) and were included in the study (median age, 60 yr; range, 28-85 yr). The incidence of complications was 18% for severe sepsis or septic shock (13/72 patients), 30% for definitive cancellation of antineoplastic chemotherapy (14/46 patients who still had active treatment), and 46% for death at week 12 (33/72 patients). Factors associated with severe sepsis or septic shock were an elevated C-reactive protein (CRP) level and an infection caused by Candida species; 4 of the 13 severe episodes (31%) were due to coagulase-negative staphylococci (CoNS). Factors associated with death at week 12 were a low median Karnofsky score, an elevated Charlson comorbidity index, the metastatic evolution of cancer, palliative care, and an elevated CRP level at presentation. Hematogenous complications (that is, infective endocarditis, septic thrombophlebitis, septic pulmonary emboli, spondylodiscitis, septic arthritis, or organ abscesses) were found in 8 patients (11%). In conclusion, patients' overall condition (comorbidities and autonomy) and elevated CRP level were associated with an unfavorable clinical outcome after a TIVAP-related infection. Candida species and CoNS were responsible for severe sepsis or septic shock.

Rehabilitation of word deafness due to auditory analysis disorder.

BACKGROUND: Word deafness refers to an inability to understand spoken words despite intact hearing. In a cognitive approach, word deafness could be explained by a deficiency at the lower perceptive level of the auditory process. The impairment of the auditory analysis system would explain a disorder of identification of speech sounds. Only few studies addressed rehabilitation of central auditory processing and have described therapy focused on phoneme discrimination. OBJECTIVE: To determine whether a specific auditory analysis rehabilitation addressing phoneme discrimination and phoneme recognition may improve oral comprehension and communication. METHOD: A single-case experimental design was used in a 65 year-old woman, with word deafness consecutive to a cerebral infarction which occurred 10 months before. Verbal naming, written expression and written comprehension were normal. Verbal comprehension, repetition and phoneme discrimination and recognition were impaired. In terms of cognitive model of auditory processing, the patient showed impairment of the auditory analysis system affecting verbal comprehension. A computerized rehabilitation of auditory analysis system was carried out in two consecutive tasks: phoneme discrimination and phoneme recognition. Errorless learning therapy was used, with a difficulty hierarchy practised from the easier to the most difficult phoneme and systematic visual cues which were progressively delayed and suppressed. This study tested the efficacy and the specificity of this therapy on the addressed tasks (phoneme discrimination and recognition), related tasks (oral comprehension and repetition), independent tasks (recognition of environmental sounds) and daily life (questionnaire). RESULTS: The phoneme discrimination and recognition impairment was stable over 4 months before therapy. After therapy, phoneme discrimination (p < 0.001) and phoneme recognition (p < 0.0001) were improved. The improvement was specific to verbal sounds recognition, while non-verbal sounds recognition was unchanged. An improvement occurred for repetition (p < 0.05) and oral comprehension (p < 0.01). The communication disability decreased (p < 0.05). CONCLUSION: In a case of word deafness, this study demonstrates not only the efficacy of a specific phoneme processing therapy but also its efficacy in the improvement of higher level of cognitive treatment such as oral comprehension and its transfer in daily life. The role of errorless therapy using systematic visual cues and difficulty hierarchy must be underlined.