LTLf/LDLf Non-Markovian Rewards

In Markov Decision Processes (MDPs), the reward obtained in a state is Markovian, i.e., depends on the last state and action. This dependency makes it difficult to reward more interesting long-term behaviors, such as always closing a door after it has been opened, or providing coffee only following a request. Extending MDPs to handle non-Markovian reward functions was the subject of two previous lines of work. Both use LTL variants to specify the reward function and then compile the new model back into a Markovian model. Building on recent progress in temporal logics over finite traces, we adopt LDLf for specifying non-Markovian rewards and provide an elegant automata construction for building a Markovian model, which extends that of previous work and offers strong minimality and compositionality guarantees

The Bankruptcy Decision and Debt Contract Renegotiations

We consider the bankruptcy law and workout practices in the United States and model bankruptcy as a strategic decision. We analyze a firm's choice between liquidation under Chapter 7, renegotiation of the debt contract in a workout, and reorganization under Chapter 11 of the bankruptcy code. Our premise is that a financially distressed firm chooses its action in order to minimize the loss in value caused by the well-known over- and under-investment problems. We show that the firm initiates a workout when it faces under-investment, and commences Chapter 11 when it faces over-investment. Some of the results are: (i) in default, total firm value and equity value increase upon the announcement of a workout and decrease upon the announcement of Chapter 11; (ii) firms with shorter maturity of debt are more likely to reorganize in a workout; (iii) among the firms that renegotiate their debt contract, the proportion of firms entering Chapter 11 is higher for firms in mature industries than for firms in growth industries.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42726/1/10679_2004_Article_159965.pd

Managerial incentives and financial signaling in product market competition

This paper demonstrates how management compensation schemes can serve as an inexpensive and sometimes even free signaling mechanism. In the particular example studied here it is shown how a contract offered to the manager of a monopolistic firm may induce him to take some actions that will credibly signal the firm's marginal cost and will deter entry if the firm is `sufficiently' efficient. This signaling mechanism is not costly to the monopolist and therefore, it may prefer this mechanism to the costlier `limit pricing' one.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28542/1/0000340.pd

The information content of equity-for-debt swaps : An investigation of analyst forecasts of firm cash flows

We demonstrate that analysts revise their forecasts of net operating income downward following the announcement of an equity-for-debt swap. Their revisions are positively correlated with the size of the stock-price reaction to the swap announcement. This evidence supports the hypothesis that announcements of equity-for-debt swaps convey information about the expected level of cash flows of the firm. We also provide evidence that this information is about transitory changes in the expected cash flows.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27659/1/0000041.pd

Plastid structure and carotenogenic gene expression in red- and white-fleshed loquat (Eriobotrya japonica) fruits

Loquat (Eriobotrya japonica Lindl.) can be sorted into red- and white-fleshed cultivars. The flesh of Luoyangqing (LYQ, red-fleshed) appears red-orange because of a high content of carotenoids while the flesh of Baisha (BS, white-fleshed) appears ivory white due to a lack of carotenoid accumulation. The carotenoid content in the peel and flesh of LYQ was approximately 68 μg g−1 and 13 μg g−1 fresh weight (FW), respectively, and for BS 19 μg g−1 and 0.27 μg g−1 FW. The mRNA levels of 15 carotenogenesis-related genes were analysed during fruit development and ripening. After the breaker stage (S4), the mRNA levels of phytoene synthase 1 (PSY1) and chromoplast-specific lycopene β-cyclase (CYCB) were higher in the peel, and CYCB and β-carotene hydroxylase (BCH) mRNAs were higher in the flesh of LYQ, compared with BS. Plastid morphogenesis during fruit ripening was also studied. The ultrastructure of plastids in the peel of BS changed less than in LYQ during fruit development. Two different chromoplast shapes were observed in the cells of LYQ peel and flesh at the fully ripe stage. Carotenoids were incorporated in the globules in chromoplasts of LYQ and BS peel but were in a crystalline form in the chromoplasts of LYQ flesh. However, no chromoplast structure was found in the cells of fully ripe BS fruit flesh. The mRNA level of plastid lipid-associated protein (PAP) in the peel and flesh of LYQ was over five times higher than in BS peel and flesh. In conclusion, the lower carotenoid content in BS fruit was associated with the lower mRNA levels of PSY1, CYCB, and BCH; however, the failure to develop normal chromoplasts in BS flesh is the most convincing explanation for the lack of carotenoid accumulation. The expression of PAP was well correlated with chromoplast numbers and carotenoid accumulation, suggesting its possible role in chromoplast biogenesis or interconversion of loquat fruit

Visualization of both proximal M2-MCA segments in patients (the Tilted-V Sign) with acute M1-MCA occlusion stroke is associated with better procedural and prognostic outcomes

IntroductionWe aimed to assess the clinical significance of M1-MCA occlusion with visualization of both MCA-M2 segments [“Tilted-V sign” (TVS)] on initial CT angiography (CTA) in patients with acute ischemic stroke (AIS) undergoing endovascular thrombectomy (EVT).MethodsData for patients with consecutive AIS undergoing EVT for large vessel occlusion (LVO) in two academic centers are recorded in ongoing databases. Patients who underwent EVT for M1-MCA occlusions ≤ 6 h from symptom onset were included in this retrospective analysis.ResultsA total of 346 patients met the inclusion criteria; 189 (55%) had positive TVS. Patients with positive TVS were younger (68 ± 14 vs. 71 ± 14 years, P = 0.028), with similar rates of vascular risk factors and baseline modified Rankin scores (mRS) 0–2. The rates of achieving thrombolysis in cerebral ischemia (TICI) 2b-3 were similar to the two groups (79%), although successful first-pass recanalization was more common with TVS (64 vs. 36%, p = 0.01). On multivariate analysis, higher collateral score [odds ratio (OR) 1.38 per unit increase, p = 0.008] and lower age (OR 0.98 per year increase, p = 0.046) were significant predictors of TVS. Patients with positive TVS had higher post-procedural Alberta Stroke Program Early CT Score (ASPECTS; 6.9 ± 2.2 vs. 5.2 ± 2.3, p = 0.001), were discharged with lower National Institutes of Health Stroke Score (NIHSS; 6±6 vs. 9±7, p = 0.003) and higher rates of mRS 0–2 (29.5 vs. 12%, p = 0.001), and had lower rates of 90-day mortality (13.2 vs. 21.6%, p = 0.038). However, TVS was not an independent predictor of functional independence (OR 2.51; 95% CI 0.7–8.3).ConclusionTilted-V Sign, an easily identifiable radiological marker, is associated with fewer recanalization attempts, better functional outcomes, and reduced mortality