Evaluating and selecting arguments in the context of higher order uncertainty.

Human and artificial reasoning has to deal with uncertain environments. Ideally, probabilistic information is available. However, sometimes probabilistic information may not be precise or it is missing entirely. In such cases we reason with higher-order uncertainty. Formal argumentation is one of the leading formal methods to model defeasible reasoning in artificial intelligence, in particular in the tradition of Dung's abstract argumentation. Also from the perspective of cognition, reasoning has been considered as argumentative and social in nature, for instance by Mercier and Sperber. In this paper we use formal argumentation to provide a framework for reasoning with higher-order uncertainty. Our approach builds strongly on Haenni's system of probabilistic argumentation, but enhances it in several ways. First, we integrate it with deductive argumentation, both in terms of the representation of arguments and attacks, and in terms of utilizing abstract argumentation semantics for selecting some out of a set of possibly conflicting arguments. We show how our system can be adjusted to perform well under the so-called rationality postulates of formal argumentation. Second, we provide several notions of argument strength which are studied both meta-theoretically and empirically. In this way the paper contributes a formal model of reasoning with higher-order uncertainty with possible applications in artificial intelligence and human cognition.

Heuristic reevaluation of the bacterial hypothesis of peptic ulcer disease in the 1950s.

Throughout the first half of the twentieth century the research on peptic ulcer disease (PUD) focused on two rivaling hypothesis: the "acidity" and the "bacterial" one. According to the received view, the latter was dismissed during the 1950s only to be revived with Warren's and Marshall's discovery of Helicobacter pylori in the 1980s. In this paper we investigate why the bacterial hypothesis was largely abandoned in the 1950s, and whether there were good epistemic reasons for its dismissal. Of special interest for our research question is Palmer's 1954 large-scale study, which challenged the bacterial hypothesis with serious counter-evidence, and which by many scholars is considered as the shifting point in the research on PUD. However, we show that: (1) The perceived refutatory impact of Palmer's study was disproportionate to its methodological rigor. This undermines its perceived status as a crucial experiment against the bacterial hypothesis. (2) In view of this and other considerations we argue that the bacterial hypothesis was worthy of pursuit in the 1950s.

Major furocoumarins in grapefruit juice I: levels and urinary metabolite(s).

Furocoumarins are phototoxic and photogenotoxic natural plant constituents occurring in cosmetics, food and drugs. Grapefruit juice is considered as a major dietary source of furocoumarins although few is known about the variability of furocoumarins in grapefruit juice. We analyzed the major furocoumarins in eight commercial grapefruit juices and in freshly prepared juices made from pink grapefruit obtained from German retailers. Bergaptol was the major furocoumarin in commercial juices, followed by bergamottin and 6',7'-dihydroxy-bergamottin (DHB), whereas an inverse picture (DHB>bergamottin>bergaptol) was obtained in freshly prepared juices. Results from different batches of a single brand of commercial juice, purchased over a period of 7 months, revealed a variability of about 50% for the individual furocoumarins and the sum. In a study with healthy volunteers, consumption of 900 ml commercial grapefruit juice (containing 12.5mg bergaptol, 6.9 mg bergamottin, and 0.6 mg DHB) resulted in an average urinary excretion of 0.36 mg free plus 13.23 mg conjugated bergaptol within 6h. Other furocoumarins were not found in urine. Thus, other grapefruit furocoumarins were obviously converted in the human body, at least in part, into bergaptol excreted in urine, since the excreted amount of bergaptol exceeded the consumed one.

Normovolemic modified ultrafiltration is associated with better preserved platelet function and less postoperative blood loss in patients undergoing complex cardiac surgery: a randomized and controlled study.

OBJECTIVE: The purpose of the investigation was to study the impact of normovolemic modified ultrafiltration (N-MUF) on hemostasis and perioperative blood loss. METHODS: Fifty patients scheduled for elective complex cardiac surgery were enrolled in this prospective, randomized, and controlled study. Patients were randomized into a control group (n = 25) or an N-MUF group (n = 25). N-MUF was performed using a BC140plus Filter (Maquet Cardiopulmonary AG, Hirrlingen, Germany) in the N-MUF group. Blood samples were taken before (T1) and 30 minutes after (T2) N-MUF in the N-MUF group and at corresponding time points in the control group. Platelet function analyses (TRAPtest, ASPItest, ADPtest) using multiple electrode aggregometry (Multiplate, Dynabyte, Munich, Germany), thrombelastometry (ROTEM, Pentapharm GmbH, Munich, Germany), and conventional laboratory coagulation analyses were performed at each time point. Intraoperative and postoperative transfusion requirements, hemostatic therapy, and blood loss were recorded. RESULTS: There were no significant group differences in demographic or surgical data. At T1, platelet aggregation revealed no significant group differences in the TRAPtest, ASPItest, or ADPtest. Platelet aggregation at T2 was significantly higher in the N-MUF group compared with the control group in the TRAPtest (65 [50/87] U vs 44 [28/51]; P < .001), the ASPItest (52 [36/69] U vs 22 [8/47] U; P = .001), or the ADPtest (39 [28/51] U vs 28 [19/39] U; P = .009). The postoperative chest tube blood loss was significantly lower in the N-MUF at 24 hours (890 [500/1100] mL vs 1075 [800/1413] mL in the N-MUF group vs the control group; P = .039) and 48 hours (900 [550/1350] mL vs 1400 [900/1750] mL; P = .026) postoperatively. Conventional laboratory coagulation analyses and thrombelastometric parameters did not differ within the groups at T1 or T2. CONCLUSIONS: N-MUF improved general platelet aggregation and reduced postoperative blood loss in a significant manner. However, performing N-MUF did not result in less postoperative transfusion requirements.