Synchronous Context-Free Grammars and Optimal Linear Parsing Strategies

Synchronous Context-Free Grammars (SCFGs), also known as syntax-directed translation schemata, are unlike context-free grammars in that they do not have a binary normal form. In general, parsing with SCFGs takes space and time polynomial in the length of the input strings, but with the degree of the polynomial depending on the permutations of the SCFG rules. We consider linear parsing strategies, which add one nonterminal at a time. We show that for a given input permutation, the problems of finding the linear parsing strategy with the minimum space and time complexity are both NP-hard

Effects of membrane and biological target on the structural and allosteric properties of recoverin: a computational approach

Recoverin (Rec) is a prototypical calcium sensor protein primarily expressed in the vertebrate retina. The binding of two Ca2+ ions to the functional EF-hand motifs induces the extrusion of a myristoyl group that increases the affinity of Rec for the membrane and leads to the formation of a complex with rhodopsin kinase (GRK1). Here, unbiased all-atom molecular dynamics simulations were performed to monitor the spontaneous insertion of the myristoyl group into a model multicomponent biological membrane for both isolated Rec and for its complex with a peptide from the GRK1 target. It was found that the functional membrane anchoring of the myristoyl group is triggered by persistent electrostatic protein-membrane interactions. In particular, salt bridges between Arg43, Arg46 and polar heads of phosphatidylserine lipids are necessary to enhance the myristoyl hydrophobic packing in the Rec-GRK1 assembly. The long-distance communication between Ca2+-binding EF-hands and residues at the interface with GRK1 is significantly influenced by the presence of the membrane, which leads to dramatic changes in the connectivity of amino acids mediating the highest number of persistent interactions (hubs). In conclusion, specific membrane composition and allosteric interactions are both necessary for the correct assembly and dynamics of functional Rec-GRK1 complex

Prep1.1 has essential genetic functions in hindbrain development and cranial neural crest cell differentiation

In this study we analysed the function of the Meinox gene prep1.1 during zebrafish development. Meinox proteins form heterotrimeric complexes with Hox and Pbx members, increasing the DNA binding specificity of Hox proteins in vitro and in vivo. However, a role for a specific Meinox protein in the regulation of Hox activity in vivo has not been demonstrated. In situ hybridization showed that prep1.1 is expressed maternally and ubiquitously up to 24 hours post-fertilization (hpf), and restricted to the head from 48 hpf onwards. Morpholino-induced prep1.1 loss-of-function caused significant apoptosis in the CNS. Hindbrain segmentation and patterning was affected severely, as revealed by either loss or defective expression of several hindbrain markers ( foxb1.2/mariposa , krox20 , pax2.1 and pax6.1 ), including anteriorly expressed Hox genes ( hoxb1a , hoxa2 and hoxb2 ), the impaired migration of facial nerve motor neurons, and the lack of reticulospinal neurons (RSNs) except Mauthner cells. Furthermore, the heads of prep1.1 morphants lacked all pharyngeal cartilages. This was not caused by the absence of neural crest cells or their impaired migration into the pharyngeal arches, as shown by expression of dlx2 and snail1 , but by the inability of these cells to differentiate into chondroblasts. Our results indicate that prep1.1 has a unique genetic function in craniofacial chondrogenesis and, acting as a member of Meinox-Pbc-Hox trimers, it plays an essential role in hindbrain development

Quantification of African Monsoon Runoff During Last Interglacial Sapropel S5

Organic‐rich sapropel layers punctuate the eastern Mediterranean sedimentary sequence,recording deep‐sea anoxic events. The timing of sapropel deposition coincides with precession minima,which are associated with the northward migration of the monsoon rain belt over North Africa. Theresultant increase in monsoon precipitation over the Sahara caused an increase in low‐δ18O freshwaterrunoff into eastern Mediterranean surface waters, which is reflected by negativeδ18O anomalies in therecords of planktic foraminiferal calcite. However, despite extensive research on sapropels, the magnitudeof monsoon intensification and freshwater runoff, along with its influence onδ18O, remains elusive. Here,we present a quantification of African monsoon freshwater runoff into the eastern Mediterranean for theperiod of deposition of last interglacial sapropel S5 (~128.3–121.5 ka). Our method uses a box model of theMediterranean Sea, which represents different water masses, and has been calibrated usingδ18O fromplanktic foraminiferal species of different depth and seasonal habitats. The model was constrained withexisting records of sea level and sea surface temperature then inverted to deconvolve theδ18O signal of thesurface‐dwelling foraminiferal speciesGlobigerinoides ruber(w) and calculate the freshwater runoff volume.Our calculated African monsoon runoff suggests large increases in freshwater discharge to the easternMediterranean (up to ~8.8 times the modern pre‐Aswan Nile discharge). Rapid onset of S5 depositionfollowing the estimated increase in runoff strongly suggests a preconditioning of the eastern Mediterraneanfor sapropel deposition. Our study also provides insight into the stratification and warming of easternMediterranean surface waters during the S5 interval.This work was supported by Australian Research Council (ARC) Australian Laureate Fellowship FL120100050 (E. J. R.) and Discovery Early Career Researcher Award DE190100042 (K. M. G.). G. M. acknowledges support from the University of Vigo program to attract excellent research talent and a generous start‐up package

Temperature Profiles Along the Root with Gutta-percha Warmed through Different Heat Sources

To evaluate temperature profiles developing in the root during warm compaction of gutta-percha with the heat sources System B and System MB Obtura (Analityc Technology, Redmond, WA, USA). Thirty extracted human incisor teeth were used. Root canals were cleaned and shaped by means of Protaper rotary files (Dentsply-Maillefer, Belgium), and imaging was performed by micro-CT (Skyscan 1072, Aartselaar, Belgium)

An all-electric-aircraft tailored SiC-based power factor correction converter with adaptive DC-link regulator

In recent years the aerospace industry has made a growing effort to develop a quieter and more environmentally friendly aircraft. In particular, several research activities have been focused on innovative solutions aimed at the design/optimization of an on-board electric system fully compatible with this new approach. A first important step in the evolution towards an All Electric Aircraft (AEA) is the replacement of the hydraulic actuators with fully electric ones. The transition process is not easy to carry out, since weight, size and reliability represent highly critical issues for aircraft applications. In this context, the significant improvements in semiconductor technologies can be exploited as a critical means to overcome the constraints mentioned. Indeed, this work proposes a Silicon Carbide (SiC) based Power Factor Correction (PFC) converter, whose design and control have been tailored in order to properly supply a wide range of on-board Electro-Mechanical Actuators (EMA). In particular, while the adopted circuit topology allows for power factor correction and bi-directional power flow, the SiC technology, thanks to the higher efficiency with respect to other semiconductor-based technologies, leads to a significant reduction in the overall system weight/volume. Furthermore, to meet the strict requirements in terms of dynamic and steady state performance imposed by the application, a novel adaptive regulator is conceived. A reduced-scale laboratory prototype of the SiC-based converter (3 kVA) is realized in order to verify the effectiveness of the proposed design and control approach