Source Code Verification for Embedded Systems using Prolog

System relevant embedded software needs to be reliable and, therefore, well tested, especially for aerospace systems. A common technique to verify programs is the analysis of their abstract syntax tree (AST). Tree structures can be elegantly analyzed with the logic programming language Prolog. Moreover, Prolog offers further advantages for a thorough analysis: On the one hand, it natively provides versatile options to efficiently process tree or graph data structures. On the other hand, Prolog's non-determinism and backtracking eases tests of different variations of the program flow without big effort. A rule-based approach with Prolog allows to characterize the verification goals in a concise and declarative way. In this paper, we describe our approach to verify the source code of a flash file system with the help of Prolog. The flash file system is written in C++ and has been developed particularly for the use in satellites. We transform a given abstract syntax tree of C++ source code into Prolog facts and derive the call graph and the execution sequence (tree), which then are further tested against verification goals. The different program flow branching due to control structures is derived by backtracking as subtrees of the full execution sequence. Finally, these subtrees are verified in Prolog. We illustrate our approach with a case study, where we search for incorrect applications of semaphores in embedded software using the real-time operating system RODOS. We rely on computation tree logic (CTL) and have designed an embedded domain specific language (DSL) in Prolog to express the verification goals.Comment: In Proceedings WLP'15/'16/WFLP'16, arXiv:1701.0014

Legal Tools for Local Control of Oil and Gas Development: Successes, Challenges, and Opportunities – Focusing on Select Eastern and Western U.S. States with Current and Potential Oil/Gas Development

In response to the rise in unconventional oil and gas drilling and hydraulic fracturing, coupled with concerns over local environmental, social, and health impacts, and weak state regulatory oversight, many communities have chosen to assert zoning or regulatory control over oil and gas development. However, the legal framework that enables and constrains local government powers varies by state, based on diverse statutory and constitutional language as well as the preemption of local control by state agency regulations governing industry development. Through a series of case studies, this article identifies successful, legally defensible strategies for local control of oil and gas development as well as the legal constraints placed on local initiatives in select eastern and western states that have experienced oil or natural gas shale development and hydraulic fracturing within the last decade. For each state examined (New York, Pennsylvania, Colorado, New Mexico, and Montana), this article describes the state oil and gas legislation that constrains local government action, relevant constitutional provisions that enable local government action, relevant zoning laws that support local government action, and how local government authority is delegated and interpreted. Overall, this article concludes that zoning authority, although still subject to conflict preemption, is a more effective and widely used source of authority than home rule charters. The success of zoning ordinances that assert control over mineral development can vary based on the content and intent of the ordinance, the comprehensiveness of the state’s regulatory scheme, and the scope of local authority that can be asserted. The most significant factor, however, is the extent to which local zoning authority is liberally construed and the stated purpose of a state’s oil and gas legislation. These two factors influence whether or not a conflict preemption will arise that invalidates a local ordinance. Of the five states examined, New York is the only state in which local governments have broadly construed land use planning authority that allows them to completely prohibit any form of mineral development. Pennsylvania municipalities can also control where drilling may occur, but cannot completely prohibit mineral development, regardless of home rule authority and despite citizens’ constitutional right to a clean environment. In Montana, which has a similar constitutional right to a clean environment, only county governments are explicitly restricted from prohibiting mineral development, while municipal and citizen-initiated zoning districts have the potential to limit or prohibit mineral development. In New Mexico, since state regulations do not occupy the entire field of regulation or address local impacts, county and city governments have the authority to fill that gap with local ordinances, as long as the ordinances do not conflict with state law. In most states, such as New Mexico, Colorado, and Pennsylvania, local ordinances are in conflict with state law if they prohibit an activity that state law permits, regardless of home rule status. In addition to discussing how home rule authority does not immunize local government action from state preemption, this article also proposes the importance of a state constitutional guarantee to a clean environment in protecting local government land use planning authority from state encroachment

Analysis of an Adaptive Switching Point for LTE TDD by Dynamic System-Level Simulations

This paper introduces an LTE system level simulatorand presents investigations of scenarios with differently balancedtraffic emergence between uplink and downlink as well asinhomogeneous distribution of link direction asymmetry. In theTDD mode of LTE, duplexing is implemented via sharing thetime domain between uplink and downlink users. This is done bydifferent switching configurations, which offer varying capacitydistributions between downlink and uplink, from a downlinkheavyconfiguration with 90 percent of the capacity in downlinkdirection to uplink heavy configurations with 60 percent uplink.We utilize the available capacity perfectly by adjusting the linkconfiguration appropriately to traffic emergence. Performancegains when selecting a configuration appropriate to the arisingtraffic compared to usage of a static configuration with equallydistributed capacity are investigated. In case of different configurations,additional interference can occur in neighbored cellsdue to distinct communication direction at the same time. Weclarify the differences between these scenarios and quantify thegains and losses when the switching point between uplink anddownlink is variable

Loss of empathy in medical school understood from the Buddhist concept of non-self

As students progress through medical school the level of empathy they entered with declines during the four years of education. Although no specific aspect of the medical curriculum has been shown to directly decrease empathy, the decline raises concern for adequate patient centered medical education. Such a loss can then lead to an erosion of ethical behavior and patient care. Although there are multiple theories regarding causes for the decline in empathy, I propose that the loss of empathy in medical school correlates with the search for a professional identity and is best understood from the perspective of Buddhist psychological theory

The decline in medical student empathy: a student's perspective

As students progress through medical school the level of empathy they entered with declines during the four years of education. Multiple explanations for the decline have been set forth in the literature such as the stressful medical curriculum, transmission of attitudes from upper level residents, and the displaced professional identity of students. I analyze the empathetic decline through the lens of a third year medical student in order to demonstrate how the challenges of developing a professional identity contribute to the empathetic loss. The decline correlates to a pursuit of self-advancement in a professional sense. I propose that in the end, this decline exists as a logical outcome from the professional expectations that medical students, faculty, and institutions place on graduating seniors. Shifting an understanding of the self away from the purely Western to a more traditionally Eastern view can help reduce the decline

The national survey of seroprevalence for evaluation of the control of Chagas disease in Brazil (2001-2008)

Um inquérito de soroprevalência de doença de Chagas foi realizado em amostra representativa da população com idade até cinco anos de toda a área rural brasileira, exceto o Estado do Rio de Janeiro. Foram estudadas 104.954 crianças, que tiveram amostras de sangue coletadas em papel de filtro e submetidas a testes de screening pelas técnicas de imunofluorescência indireta (IFI) e ELISA em um único laboratório. Todas as amostras com resultados positivos ou indeterminados, juntamente com 10% daquelas com resultados negativos, foram enviadas para um laboratório de referência e aí submetidas a novos testes por IFI e ELISA, além de western blot TESA (Trypomastigote Excreted Secreted Antigen). Para as crianças com resultado final positivo foi agendada uma re-visita para coleta de sangue venoso do próprio participante e das suas mães e familiares. Da avaliação do conjunto de testes resultaram 104 (0,1%) resultados positivos, dos quais apenas 32 (0,03%) foram confirmadas como infectadas. Destas, 20 (0,02%) com positividade materna concomitante (sugerindo transmissão congênita), 11 (0,01%) com positividade apenas na criança (indicativo de provável transmissão vetorial), e uma criança positiva cuja mãe havia falecido. Em 41 situações ocorreu confirmação apenas nas mães, sugerindo transferência passiva de anticorpos maternos; em 18 a positividade não se confirmou nem nas crianças nem nas suas mães; e em 13 não foi possível a localização de ambas. As 11 crianças que adquiriram a infecção por provável via vetorial distribuíram-se predominantemente na região nordeste (Piauí, Ceará, Rio Grande do Norte, Paraíba e Alagoas), acrescidas de um caso no Amazonas e um no Paraná. Dos 20 casos com provável transmissão congênita sobressaiu-se o Rio Grande do Sul, com 60% deles, representando este o primeiro relato de diferenças regionais na transmissão congênita da doença de Chagas no Brasil, possivelmente relacionada à existência de Trypanosoma cruzi grupo IId e IIe, atualmente classificados como TcV e TcVI. Os resultados deste inquérito apontam para a virtual inexistência de transmissão de doença de Chagas por via vetorial no Brasil em anos recentes, resultante da combinação dos programas regulares e sistemáticos de combate á moléstia e de mudanças de natureza socioeconômica observadas no país ao longo das últimas décadas. Por outro lado, reforçam a necessidade de manutenção de um programa de controle que garanta a consolidação deste grande avanço.A survey for seroprevalence of Chagas disease was held in a representative sample of Brazilian individuals up to 5 years of age in all the rural areas of Brazil, with the single exception of Rio de Janeiro State. Blood on filter paper was collected from 104,954 children and screened in a single laboratory with two serological tests: indirect immunofluorescence and enzyme linked immunoassay. All samples with positive or indetermined results, as well as 10% of all the negative samples were submitted to a quality control reference laboratory, which performed both tests a second time, as well as the western blot assay of TESA (Trypomastigote Excreted Secreted Antigen). All children with confirmed final positive result (n = 104, prevalence = 0.1%) had a follow-up visit and were submitted to a second blood collection, this time a whole blood sample. In addition, blood samples from the respective mothers and familiar members were collected. The infection was confirmed in only 32 (0.03%) of those children. From them, 20 (0.025%) had maternal positive results, suggesting congenital transmission; 11 (0.01%) had non-infected mothers, indicating a possible vectorial transmission; and in one whose mother had died the transmission mechanism could not be elucidated. In further 41 visited children the infection was confirmed only in their mothers, suggesting passive transference of maternal antibodies; in other 18, both child and mother were negative; and in 13 cases both were not localized. The 11 children that acquired the infection presumably through the vector were distributed mainly in the Northeast region of Brazil (States of Piauí, Ceará, Rio Grande do Norte, Paraíba and Alagoas), in addition to one case in Amazonas (North region) and another in Parana (South region). Remarkably, 60% of the 20 cases of probably congenital transmission were from a single State, Rio Grande do Sul, with the remaining cases distributed in other states. This is the first report demonstrating regional geographical differences in the vertical transmission of Chagas disease in Brazil, which probably reflects the predominant Trypanosoma cruzi group IId and IIe (now TcV and TcVI) found in this state. Overall, these results show that the regular and systematic control programs against the transmission of Chagas disease, together with socioeconomic changes observed in Brazil in the last decades, interrupted the vectorial transmission in Brazil, resumed in the few cases found in this national survey. Furthermore they reinforce the need for maintenance of control programs for the consolidation of this major advance in public health

Comparison between the classical and artificial xenodiagnosis in chronical Chagas' disease

O xenodiagnóstico (xeno) clássico e artificial feitos com Dipatalogaster maximus de primeiro estágio foi realizado simultaneamente em 57 pacientes com infecção chagásica crônica (22 do sexo masculino e 35 do sexo feminino, com idades entre 7 e 80 anos). Exceto dois pacientes com clínica de megaesôfago, os demais tinham dois exames sorológicos prévios positivos sendo feita nova sorológia no decorrer do estudo. Os pacientes eram provenientes do ambulatório do Hospital Universitário de Brasília (HUB) ou eram residentes no município de Mambaí, GO. Dos 57 pacientes, 24 (42%) apresentaram xenodiagnósticos positivos. Dos 114 xenodiagnósticos realizados, 36 (32%) foram positivos. A comparação das duas técnicas não mostrou diferença estatisticamente significante (p = 0,42), porém o xeno artificial apresenta vantagem porque o sangue é oferecido aos triatomíneos através de um aparelho enquanto, no xeno clássico, os triatomíneos sugam através da pele do paciente.Classical and artificial xenodiagnostic techniques made with Dipetalogaster maximus of first stage were performed simultaneously in 57 patients with chronic T. cruzi infection (22 male and 35 female patients, aged 7-80 years). With the exception of two patients with megaoesophagus, all had two previous positive serological reaction and a further test was done at the time of the examination. The patients came from the outpatient department of the university hospital or were resident in Mambaí, Goiás. Of the 57 patients, 24 (42%) had a positive xenodiagnoses. Of a total of 114 tests performed, 36(32%) were positive. Comparing the two xenodiagnostic techniques, no significant advantage was apparent statistically (p = 0,42), but the artificial technique has advantages because the blood is offered for triatomines through a device while in the classical technique, the triatomines suck through the patient's skin