Development of New Taro Varieties through Breeding

The production of new crop varieties through hybridization is the only stable method of crop improvement. As a program, crop improvement through breeding has been a major project of most research centers and institutes. An example of the value of plant breeding was demonstrated by the release of IR-8 or "miracle rice" by the International Rice Research Institute in the mid-1960's. Other crops like corn and wheat had similar dramatic and valuable contributions. In Hawaii, new variety development has been and continues to be an important and well supported program of the Hawaiian Sugar Planters Association. Although taro is considered to be one of the oldest cultivated crops, there has virtually been no research program aimed at improving the varieties existing throughout the world. Because of the importance of taro as a commercial and staple crop in Hawaii and many countries in Asia and the Pacific area, an organized crop improvement program through breeding should be established and supported. Some of the advantages, problems, and general method of hybridizing taro are discussed

Generalizing Refinement Operators to Learn Prenex Conjunctive Normal Forms

Inductive Logic Programming considers almost exclusively universally quantied theories. To add expressiveness, prenex conjunctive normal forms (PCNF) with existential variables should also be considered. ILP mostly uses learning with refinement operators. To extend refinement operators to PCNF, we should first do so with substitutions. However, applying a classic substitution to a PCNF with existential variables, one often obtains a generalization rather than a specialization. In this article we define substitutions that specialize a given PCNF and a weakly complete downward refinement operator. Moreover, we analyze the complexities of this operator in different types of languages and search spaces. In this way we lay a foundation for learning systems on PCNF. Based on this operator, we have implemented a simple learning system PCL on some type of PCNF.learning;PCNF;completeness;refinement;substitutions

Pinnatiphycus menouana gen. et sp. nov. (Rhodophyta: Dicranemataceae) from New Caledonia and Fiji (South Pacific): vegetative and reproductive morphology and molecular phylogeny

A new tropical genus and species belonging to the family Dicranemataceae, Pinnatiphycus menouana, is described from lagoon and outer reef-slope habitats in New Caledonia and Fiji. The new genus differs from other members of the family by the unique combination of the following characters: (1) tetrasporangia borne in terminal nemathecia on lateral cylindrical branchlets; and (2) the disposition of cystocarps along lateral branchlets rather than on the main axis itself. The new species differs from Peltasta australis J. Agardh by the presence of cylindrical lateral branchlets along the flattened main axes and the occurrence of reproductive structures in terminal, subterminal or basal positions on the lateral branchlets. It differs from subtropical Reptataxis rhizophora (Lucas) Kraft from Lord Howe Island by the presence of both yellowish refractive medullary cell clusters and cylindrical lateral branches bearing subapical tetrasporangial sori and cystocarps, as well as a central fusion cell and the production of carposporangia in chains of two to three rather than four to six. rbcL molecular analysis of Fijian samples unequivocally places the genus in the family Dicranemataceae with 100% bootstrap support, strongly relating it to two species of Tylotus. The family itself, however, received only weak bootstrap support (66%) for distinguishing it from the clade containing the virtually Australian-endemic families Mychodeaceae and Acrotylaceae. Pinnatiphycus favors deepwater habitats (65–70 m) with low light intensities or shallower (, 30 m) but turbid high-current areas, which may have contributed to it being overlooked in the past

Generalizing Refinement Operators to Learn Prenex Conjunctive Normal Forms

Inductive Logic Programming considers almost exclusively universally quantied theories. To add expressiveness, prenex conjunctive normal forms (PCNF) with existential variables should also be considered. ILP mostly uses learning with refinement operators. To extend refinement operators to PCNF, we should first do so with substitutions. However, applying a classic substitution to a PCNF with existential variables, one often obtains a generalization rather than a specialization. In this article we define substitutions that specialize a given PCNF and a weakly complete downward refinement operator. Moreover, we analyze the complexities of this operator in different types of languages and search spaces. In this way we lay a foundation for learning systems on PCNF. Based on this operator, we have implemented a simple learning system PCL on some type of PCNF

A 160Gb/s (4x40) WDM O-band Tx subassembly using a 4-ch array of silicon rings co-packaged with a SiGe BiCMOS IC driver

We present a 400 (8×50) Gb/s-capable RM-based Si-photonic WDM O-band TxRx with 1.17nm channel spacing for high-speed optical interconnects and demonstrate successful 50Gb/s-NRZ TxRx operation achieving a ~4.5dB Tx extinction ratio under 2.15Vpp drive

Evidence for non-thermal X-ray emission from the double Wolf-Rayet colliding-wind binary Apep

Context. Massive colliding-wind binaries (CWBs) can be non-thermal sources. The emission produced in their wind-collision region (WCR) encodes information of both the shock properties and the relativistic electrons accelerated in them. The recently discovered system Apep, a unique massive system hosting two Wolf-Rayet stars, is the most powerful synchrotron radio emitter among the known CWBs. It is an exciting candidate in which to investigate the non-thermal processes associated with stellar wind shocks. Aims. We intend to break the degeneracy between the relativistic particle population and the magnetic field strength in the WCR of Apep by probing its hard X-ray spectrum, where inverse-Compton (IC) emission is expected to dominate. Methods. We observed Apep with NuSTAR for 60 ks and combined this with a reanalysis of a deep archival XMM-Newton observation to better constrain the X-ray spectrum. We used a non-thermal emission model to derive physical parameters from the results. Results. We detect hard X-ray emission consistent with a power-law component from Apep. This is compatible with IC emission produced in the WCR for a magnetic field of ≈105–190 mG, corresponding to a magnetic-to-thermal pressure ratio in the shocks of ≈0.007–0.021, and a fraction of ∼1.5 × 10−4 of the total wind kinetic power being transferred to relativistic electrons. Conclusions. The non-thermal emission from a CWB is detected for the first time in radio and at high energies. This allows us to derive the most robust constraints so far for the particle acceleration efficiency and magnetic field intensity in a CWB, reducing the typical uncertainty of a few orders of magnitude to just within a factor of a few. This constitutes an important step forward in our characterisation of the physical properties of CWBs

Oxidative Stress in Neurodegenerative Diseases: Mechanisms and Therapeutic Perspectives

The incidence and prevalence of neurodegenerative diseases (ND) increase with life expectancy. This paper reviews the role of oxidative stress (OS) in ND and pharmacological attempts to fight against reactive oxygen species (ROS)-induced neurodegeneration. Several mechanisms involved in ROS generation in neurodegeneration have been proposed. Recent articles about molecular pathways involved in ROS generation were reviewed. The progress in the development of neuroprotective therapies has been hampered because it is difficult to define targets for treatment and determine what should be considered as neuroprotective. Therefore, the attention was focused on researches about pharmacological targets that could protect neurons against OS. Since it is necessary to look for genes as the ultimate controllers of all biological processes, this paper also tried to identify gerontogenes involved in OS and neurodegeneration. Since neurons depend on glial cells to survive, recent articles about the functioning of these cells in aging and ND were also reviewed. Finally, clinical trials testing potential neuroprotective agents were critically reviewed. Although several potential drugs have been screened in in vitro and in vivo models of ND, these results were not translated in benefit of patients, and disappointing results were obtained in the majority of clinical trials

On the conservation of the slow conformational dynamics within the amino acid kinase family: NAGK the paradigm

N-Acetyl-L-Glutamate Kinase (NAGK) is the structural paradigm for examining the catalytic mechanisms and dynamics of amino acid kinase family members. Given that the slow conformational dynamics of the NAGK (at the microseconds time scale or slower) may be rate-limiting, it is of importance to assess the mechanisms of the most cooperative modes of motion intrinsically accessible to this enzyme. Here, we present the results from normal mode analysis using an elastic network model representation, which shows that the conformational mechanisms for substrate binding by NAGK strongly correlate with the intrinsic dynamics of the enzyme in the unbound form. We further analyzed the potential mechanisms of allosteric signalling within NAGK using a Markov model for network communication. Comparative analysis of the dynamics of family members strongly suggests that the low-frequency modes of motion and the associated intramolecular couplings that establish signal transduction are highly conserved among family members, in support of the paradigm sequence→structure→dynamics→function © 2010 Marcos et al