96 research outputs found
Generating Property-Directed Potential Invariants By Backward Analysis
This paper addresses the issue of lemma generation in a k-induction-based
formal analysis of transition systems, in the linear real/integer arithmetic
fragment. A backward analysis, powered by quantifier elimination, is used to
output preimages of the negation of the proof objective, viewed as unauthorized
states, or gray states. Two heuristics are proposed to take advantage of this
source of information. First, a thorough exploration of the possible
partitionings of the gray state space discovers new relations between state
variables, representing potential invariants. Second, an inexact exploration
regroups and over-approximates disjoint areas of the gray state space, also to
discover new relations between state variables. k-induction is used to isolate
the invariants and check if they strengthen the proof objective. These
heuristics can be used on the first preimage of the backward exploration, and
each time a new one is output, refining the information on the gray states. In
our context of critical avionics embedded systems, we show that our approach is
able to outperform other academic or commercial tools on examples of interest
in our application field. The method is introduced and motivated through two
main examples, one of which was provided by Rockwell Collins, in a
collaborative formal verification framework.Comment: In Proceedings FTSCS 2012, arXiv:1212.657
The Impact Of Hospital Nursing On Postsurgical Sepsis
Sepsis is common, deadly, and costly. Over 1 million patients are affected each year, and as many as half of them die. The cost of care exceeds that of any hospital admission. Early diagnosis and rapid response are essential elements of effective treatment. Nurses providing direct patient care have the patient contact and clinical knowledge to make them critical components of inpatient sepsis prevention, surveillance, and response. There is a large research literature on sepsis. Many studies evaluate clinical interventions and examine patient risk factors. These studies inform evidence-based guidelines, such as the Surviving Sepsis Campaign. Despite the international expert consensus on sepsis treatment that this campaign represents, sepsis incidence and mortality varies by hospital. The Quality Health Outcomes Model posits that system (and patient) characteristics mediate the relationship between interventions and outcomes such that in actual practice, clinical guidelines often do not have their intended effects. Hospital nursing characteristics are system-level features that may help explain institutional differences in sepsis incidence and mortality. This study explored the relationship between hospital nursing characteristics and sepsis. Specifically, it determined the impact of nurse staffing, education, and the work environment among postsurgical patients on the odds of sepsis (Aim 1), and on mortality among septic patients (Aim 2). This was a cross-sectional, secondary analysis of nurse survey responses, patient discharge abstracts, and hospital administrative data from hospitals in four states. The sample included 1,435,919 patients who were hospitalized for general, orthopedic, or vascular surgeries from 2005 through 2007, 23,603 nurse survey respondents, and the 503 hospitals associated with these subjects. Logistic regression was used to model the relationship between hospital nursing characteristics and patient outcomes. There was a significant association between hospital work environment and postsurgical sepsis and between nurse education and death after sepsis. Surgical patients in hospitals with better nurse work environment experienced lower odds of sepsis (OR 0.93; p=0.002). Postsurgical septic patients in hospitals with a higher percentage of BSN-prepared nurses had lower odds of death (OR 0.94; p\u3c0.001). Nursing resources were associated with patient outcomes and may be a mechanism for administrators to reduce sepsis incidence and mortality
A Public Literary Twitter Role-Play
Curatorial note from Digital Pedagogy in the Humanities: Petra Dierkes-Thrun has run several iterations of the public literary Twitter role-play assignment, having students reenact and inhabit texts like The Portrait of Dorian Gray, Lolita, and Frankenstein. Each experiment uses a different prompt to engage students in her physical class and also virtual participants around the world. Her larger goals focus on âclose-reading, critical thinking, and critical writing,â allowing students to comment on the text and also put their readings to use, drawing nonscholars into animated language-play and literary discussion. Dierkes-Thrun does not make students participate openly online but invites them to. When asking students to work on the open Web, itâs important to give thought to student privacy, data, and FERPA (the Family Educational Rights and Privacy Act), but what is most important is that students be given space to make informed choices about how they will occupy the Web
The Association of Meat Intake With All-Cause Mortality and Acute Myocardial Infarction Is Age-Dependent in Patients With Stable Angina Pectoris
Background: Red and processed meat intake have been associated with increased risk of morbidity and mortality, and a restricted intake is encouraged in patients with cardiovascular disease. However, evidence on the association between total meat intake and clinical outcomes in this patient group is lacking.
Objectives: To investigate the association between total meat intake and risk of all-cause mortality, acute myocardial infarction, cancer, and gastrointestinal cancer in patients with stable angina pectoris. We also investigated whether age modified these associations.
Materials and Methods: This prospective cohort study consisted of 1,929 patients (80% male, mean age 62 years) with stable angina pectoris from the Western Norway B-Vitamin Intervention Trial. Dietary assessment was performed by the administration of a semi-quantitative food frequency questionnaire. Cox proportional hazards models were used to investigate the association between a relative increase in total meat intake and the outcomes of interest.
Results: The association per 50 g/1,000 kcal higher intake of total meat with morbidity and mortality were generally inconclusive but indicated an increased risk of acute myocardial infarction [HR: 1.26 (95% CI: 0.98, 1.61)] and gastrointestinal cancer [1.23 (0.70, 2.16)]. However, we observed a clear effect modification by age, where total meat intake was associated with an increased risk of mortality and acute myocardial infarction among younger individuals, but an attenuation, and even reversal of the risk association with increasing age.
Conclusion: Our findings support the current dietary guidelines emphasizing a restricted meat intake in cardiovascular disease patients but highlights the need for further research on the association between meat intake and health outcomes in elderly populations. Future studies should investigate different types of meat separately in other CVD-cohorts, in different age-groups, as well as in the general population.publishedVersio
Paternity of Subordinates Raises Cooperative Effort in Cichlids
Background
In cooperative breeders, subordinates generally help a dominant breeding pair to raise offspring. Parentage studies have shown that in several species subordinates can participate in reproduction. This suggests an important role of direct fitness benefits for cooperation, particularly where groups contain unrelated subordinates. In this situation parentage should influence levels of cooperation. Here we combine parentage analyses and detailed behavioural observations in the field to study whether in the highly social cichlid Neolamprologus pulcher subordinates participate in reproduction and if so, whether and how this affects their cooperative care, controlling for the effect of kinship.
Methodology/Principal Findings
We show that: (i) male subordinates gained paternity in 27.8% of all clutches and (ii) if they participated in reproduction, they sired on average 11.8% of young. Subordinate males sharing in reproduction showed more defence against experimentally presented egg predators compared to subordinates not participating in reproduction, and they tended to stay closer to the breeding shelter. No effects of relatedness between subordinates and dominants (to mid-parent, dominant female or dominant male) were detected on parentage and on helping behaviour.
Conclusions/Significance
This is the first evidence in a cooperatively breeding fish species that the helping effort of male subordinates may depend on obtained paternity, which stresses the need to consider direct fitness benefits in evolutionary studies of helping behaviour
Helper Response to Experimentally Manipulated Predation Risk in the Cooperatively Breeding Cichlid Neolamprologus pulcher
Background
We manipulated predation risk in a field experiment with the cooperatively breeding cichlid Neolamprologus pulcher by releasing no predator, a medium- or a large-sized fish predator inside underwater cages enclosing two to three natural groups. We assessed whether helpers changed their helping behaviour, and whether within-group conflict changed, depending on these treatments, testing three hypotheses: âpay-to-stayâ PS, ârisk avoidanceâ RA, or (future) reproductive benefits RB. We also assessed whether helper food intake was reduced under risk, because this might reduce investments in other behaviours to save energy.
Methodology/Principal Findings
Medium and large helpers fed less under predation risk. Despite this effect helpers invested more in territory defence, but not territory maintenance, under the risk of predation (supporting PS). Experimentally covering only the breeding shelter with sand induced more helper digging under predation risk compared to the control treatment (supporting PS). Aggression towards the introduced predator did not differ between the two predator treatments and increased with group member size and group size (supporting PS and RA). Large helpers increased their help ratio (helping effort/breeder aggression received, âpunishmentâ by the dominant pair in the group) in the predation treatments compared to the control treatment, suggesting they were more willing to PS. Medium helpers did not show such effects. Large helpers also showed a higher submission ratio (submission/ breeder aggression received) in all treatments, compared to the medium helpers (supporting PS).
Conclusions/Significance
We conclude that predation risk reduces helper food intake, but despite this effect, helpers were more willing to support the breeders, supporting PS. Effects of breeder punishment suggests that PS might be more important for large compared to the medium helpers. Evidence for RA was also detected. Finally, the results were inconsistent with RB
The sources, impact and management of car park runoff pollution: a review
Traffic emissions contribute significantly to the build-up of diffuse pollution loads on urban surfaces with their subsequent mobilisation and direct discharge posing problems for receiving water quality. This review focuses on the impact and mitigation of solids, metals, nutrients and organic pollutants in the runoff deriving from car parks. Variabilities in the discharged pollutant levels and in the potentials for pollutant mitigation complicate an impact assessment of car park runoff. The different available stormwater best management practices and proprietary devices are reported to be capable of reductions of between 20% and almost 100% for both suspended solids and a range of metals. This review contributes to prioritising the treatment options which can achieve the appropriate pollutant reductions whilst conforming to the site requirements of a typical car park. By applying different treatment scenarios to the runoff from a hypothetical car park, it is shown that optimal performance, in terms of ecological benefits for the receiving water, can be achieved using a treatment train incorporating permeable paving and bioretention systems. The review identifies existing research gaps and emphasises the pertinent management practices as well as design issues which are relevant to the mitigation of car park pollution
Lösungsstrategien zur Verminderung von EintrÀgen von urbanem Plastik in limnische Systeme - PLASTRAT - Synthesebericht
Der Einsatz von Plastik gehört zu den groĂen Errungenschaften unserer Zeit. Die Nutzung
von Plastik in unseren verschiedenen Lebensbereichen ermöglicht uns heute Vieles. Dabei
setzen wir Plastik oft ein, ohne dass uns dies bewusst ist. Wieviel âvirtuelles Plastikâ war
allein notwendig, um diesen Synthesebericht zu erstellen? Wieviel Plastik benötigen Sie
gerade, um diesen Synthesebericht zu lesen?
Wie so oft, so hat auch der Einsatz von Plastik zwei Seiten: den positiven Errungenschaften
stehen negative Auswirkungen gegenĂŒber, vor allem nach der Nutzung von Plastik. Im Fokus
stehen hierbei Fragestellungen der Toxikologie sowie der Abfallverwertung. Im Gegensatz
zu vielen anderen Stoffen, mit denen wir tĂ€glich in BerĂŒhrung sind, hat Plastik die Eigenschaft,
dass sich kleinste Partikel bilden. So ist es nicht verwunderlich, dass sich mittlerweile
in allen Umweltmedien Mikroplastikpartikel finden lassen.
Die Idee von PLASTRAT war es, in einem interdisziplinĂ€ren Team AnsĂ€tze fĂŒr die Verminderung
von EintrĂ€gen von Plastik in GewĂ€sser zu untersuchen. Dabei standen ĂŒber den
Ansatz der systemischen Risikoanalyse die unterschiedlichen Sektoren im Fokus, angefangen
von der Erzeugung, ĂŒber die Nutzung bis hin zu den Eintragspfaden und die toxikologische
Bewertung. Der Synthesebericht fasst die Ergebnisse von PLASTRAT zusammen.
Vor allem zeigt der Synthesebericht die groĂen Herausforderungen sowie LösungsansĂ€tze
zum Thema Mikroplastik auf. Dabei wird auch deutlich, dass wir bei vielen Fragestellungen
zum Umgang mit Plastik erst am Anfang stehen.
Die ersten Ideen zu PLASTRAT entstanden 2016. In den vergangenen fĂŒnf Jahren stand
das Thema Plastik im Fokus von Ăffentlichkeit und Presse. In dieser Zeit gab es bereits
wichtige VerÀnderungen beim Einsatz von Plastik bei diversen Produkten, beispielsweise
durch die Substitution durch alternative Materialien. Dies zeigt deutlich, dass eine BewusstseinsverÀnderung
stattgefunden hat, die sich sicherlich in der Zukunft fortsetzten wird.
Die Arbeiten und Diskussionen im Projektteam von PLASTRAT waren spannend. In vielen
Projektbesprechungen wurde an den Forschungsfragestellungen gearbeitet und nach Lösungen
gesucht. Es gab einen intensiven persönlichen Austausch mit allen am Projekt beteiligten
Personen, so dass uns die seit 2020 geltenden EinschrÀnkungen durch die
Corona-Pandemie nicht immer leichtgefallen sind.
Wir möchten uns bei allen bedanken, die bei PLASTRAT mitgewirkt haben. Allen Lesern
des Syntheseberichts wĂŒnschen wir viele Freude beim Lesen und hoffen, dass wir Ihnen
einen Impuls fĂŒr den zukĂŒnftigen Umgang mit (Mikro-)Plastik geben können
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