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Form factors and taper functions are used for the quantitative and qualitative description of tree stem shape. In southeastern Mexico, there are plantations of Pinus caribaea var. hondurensis (Sénécl.) W.H. Barrett & Golfari, Pinus elliottii var. elliottii Engelm., and hybrids between these species to simultaneously produce resin and wood. Farmers need to know whether the practice of resin tapping to death has a negative impact on tree shape and volume of the wood produced. To answer these questions, this study compared the shape, taper, and volume of resin-tapped and untapped trees from three P. caribaea origins. A total of 198 trees (99 resin-tapped and 99 untapped) were measured in all diameter categories of the plantation. Total volume models, along with a compatible taper system and variable merchantable timber volume, were fitted using linear and nonlinear regression analyses. To compensate for the lack of initial tree size data prior to tapping, indicator variables (dummies) and an additive structure were used to parameterize volume and taper models. Untapped trees accumulated greater volume than tapped trees. In contrast, the form factor (ff) of resin-tapped trees (ff = 0.51) was greater than that of untapped trees (ff = 0.45). The form factor increased due to tapping between 4 and 7 % depending on the origin, although the hybrid P. caribaea × P. elliottii presented the most desirable stem geometry in tapped and untapped trees. Based on the Demaerschalk model, the variability is estimated at 99 and 97 % of the merchantable and taper volumes, respectively. [ABSTRACT FROM AUTHOR]

Knowledge, perceptions, and attitudes toward raptors were assessed from July to December 2019 through exploratory research conducted online (n = 278) and in-depth interviews (n = 18) with participants having knowledge of information technologies in urban areas of the Riviera Maya, Quintana Roo, Mexico. Most respondents were young (ages 13–37), permanent residents of the cities of Cancun, Playa del Carmen, Puerto Morelos, and Tulum. We found heterogeneous attitudes toward raptors, including "scientific," "environmentalist-conservationist," "aesthetic," "dominant," and "utilitarian." Our results suggest that most participants had a relatively high level of knowledge, positive perceptions, and environmentalist-conservationist attitudes toward raptors, probably due to the nature of the convenient sampling applied. We recommend further studies on human-raptor relations in urban and rural localities of coastal Quintana Roo, including residents of Mayan origins. This information may help support strategies and programs to reduce negative perceptions and indifference toward raptors and might support their conservation in the Mexican Riviera Maya. [ABSTRACT FROM AUTHOR]

This paper addresses a class of discrete-time Markov decision processes in Borel spaces with a finite number of cost constraints. The constrained control model considers costs of discounted type with state-dependent discount factors which are subject to external disturbances. Our objective is to prove the existence of optimal control policies and characterize them according to certain optimality criteria. Specifically, by rewriting appropriately our original constrained problem as a new one on a space of occupation measures, we apply the direct method to show solvability. Next, the problem is defined as a convex program, and we prove that the existence of a saddle point of the associated Lagrangian operator is equivalent to the existence of an optimal control policy for the constrained problem. Finally, we turn our attention to multi-objective optimization problems, where the existence of Pareto optimal policies can be obtained from the existence of saddle-points of the aforementioned Lagrangian or equivalently from the existence of optimal control policies of constrained problems. [ABSTRACT FROM AUTHOR]

Background: To study the possible dosimetric benefits of a Hybrid planning technique that consists of combining intensity modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) for whole brain radiation therapy hippocampal-sparing (WBRTHS). Materials and Methods: Three types of plans were made for 15 patients, namely Hybrid, pure IMRT, and pure VMAT and retrospectively compared. Each plan was made using contoured structures on computed tomographic (CT) images fused with magnetic resonance imaging (MRI). The homogeneity (HI) and conformity (CI) indices of the planning target volumes (PTVs) were calculated to establish the dosimetric quality in all plans. The dose received to organs at risk (OARs), number of monitor units (MUs) and treatment time were evaluated for each type of planning technique. Results: Hybrid plans showed superior homogeneity (p = 0.04) and conformity (p = 0.01) indices compared to IMRT and VMAT plans. In terms of hippocampus sparing, the Hybrid technique showed almost equal D100% and maximum dose (Dmax) values compared to the other techniques, but without statistical significance (p> 0.05); however, there was a significant difference for the left hippocampus, where the IMRT technique obtained the best result (p <0.001). Hybrid plan values for dose delivered to the remaining OARs, MUs and treatment times were intermediate between those of IMRT and VMAT. Conclusion: Compared to the IMRT and VMAT plans, the hybrid plan showed improved dosimetric plan quality along with intermediate dose values to the OARs. [ABSTRACT FROM AUTHOR]

Reversal learning measures the ability to form flexible associations between choice outcomes with stimuli and actions that precede them. This type of learning is thought to rely on several cortical and subcortical areas, including the highly interconnected orbitofrontal cortex (OFC) and basolateral amygdala (BLA), and is often impaired in various neuropsychiatric and substance use disorders. However, the unique contributions of these regions to stimulus- and action-based reversal learning have not been systematically compared using a chemogenetic approach particularly before and after the first reversal that introduces new uncertainty. Here, we examined the roles of ventrolateral OFC (vlOFC) and BLA during reversal learning. Male and female rats were prepared with inhibitory designer receptors exclusively activated by designer drugs targeting projection neurons in these regions and tested on a series of deterministic and probabilistic reversals during which they learned about stimulus identity or side (left or right) associated with different reward probabilities. Using a counterbalanced within-subject design, we inhibited these regions prior to reversal sessions. We assessed initial and pre-/post-reversal changes in performance to measure learning and adjustments to reversals, respectively. We found that inhibition of the ventrolateral orbitofrontal cortex (vlOFC), but not BLA, eliminated adjustments to stimulus-based reversals. Inhibition of BLA, but not vlOFC, selectively impaired action-based probabilistic reversal learning, leaving deterministic reversal learning intact. vlOFC exhibited a sex-dependent role in early adjustment to action-based reversals, but not in overall learning. These results reveal dissociable roles for BLA and vlOFC in flexible learning and highlight a more crucial role for BLA in learning meaningful changes in the reward environment. [ABSTRACT FROM AUTHOR]