Optical and Gamma-Ray Variability Behaviors of 3C 454.3 from 2006 to 2011

We present our photometric monitoring of a flat spectrum radio quasar (FSRQ) 3C 454.3 at Yunnan observatories from 2006 to 2011. We find that the optical color of 3C 454.3 shows obvious redder-when-brighter trend, which reaches a saturation stage when the source is brighter than 15.15 mag at V band. We perform a simulation with multiple values of disk luminosity and spectral index to reproduce the magnitude-color diagram. The results show that the contamination caused by the disk radiation alone is difficult to produce the observed color variability. The variability properties during the outburst in December 2009 are also compared with $\gamma$-ray data derived from Fermi $\gamma$-ray space telescope. The flux variation of these two bands follow a linear relation with $F_{\gamma} \propto F_R^{1.14\pm0.07}$, which provides an observational evidence for external Compton process in 3C 454.3. Meanwhile, this flux correlation indicates that electron injection is the main mechanism for variability origin. We also explore the variation of the flux ratio $F_{\gamma}/F_R$ and the detailed structures in the lightcurves, and discuss some possible origins for the detailed variability behaviors.Comment: accepted for publication in The Astrophysical Journal, 5 figures, 2 table

Robot Task Planning Based on Large Language Model Representing Knowledge with Directed Graph Structures

Traditional robot task planning methods face challenges when dealing with highly unstructured environments and complex tasks. We propose a task planning method that combines human expertise with an LLM and have designed an LLM prompt template, Think_Net_Prompt, with stronger expressive power to represent structured professional knowledge. We further propose a method to progressively decompose tasks and generate a task tree to reduce the planning volume for each task, and we have designed a strategy to decouple robot task planning. By dividing different planning entities and separating the task from the actual machine binding process, the task planning process becomes more flexible. Research results show that our method performs well in handling specified code formats, understanding the relationship between tasks and subtasks, and extracting parameters from text descriptions. However, there are also problems such as limited complexity of task logic handling, ambiguity in the quantity of parts and the precise location of assembly. Improving the precision of task description and cognitive structure can bring certain improvements. https://github.com/NOMIzy/Think_Net_Promp

Phylogeny and evolutionary history of Leymus (Triticeae; Poaceae) based on a single-copy nuclear gene encoding plastid acetyl-CoA carboxylase

<p>Abstract</p> <p>Background</p> <p>Single- and low- copy genes are less likely subject to concerted evolution, thus making themselves ideal tools for studying the origin and evolution of polyploid taxa. <it>Leymus </it>is a polyploid genus with a diverse array of morphology, ecology and distribution in Triticeae. The genomic constitution of <it>Leymus </it>was assigned as NsXm, where Ns was presumed to be originated from <it>Psathyrostachys</it>, while Xm represented a genome of unknown origin. In addition, little is known about the evolutionary history of <it>Leymus</it>. Here, we investigate the phylogenetic relationship, genome donor, and evolutionary history of <it>Leymus </it>based on a single-copy nuclear <it>Acc1 </it>gene.</p> <p>Results</p> <p>Two homoeologues of the <it>Acc1 </it>gene were isolated from nearly all the sampled <it>Leymus </it>species using allele-specific primer and were analyzed with those from 35 diploid taxa representing 18 basic genomes in Triticeae. Sequence diversity patterns and genealogical analysis suggested that (1) <it>Leymus </it>is closely related to <it>Psathyrostachys</it>, <it>Agropyron</it>, and <it>Eremopyrum</it>; (2) <it>Psathyrostachys juncea </it>is an ancestral Ns-genome donor of <it>Leymus </it>species; (3) the Xm genome in <it>Leymus </it>may be originated from an ancestral lineage of <it>Agropyron </it>and <it>Eremopyrum triticeum</it>; (4) the <it>Acc1 </it>sequences of <it>Leymus </it>species from the Qinghai-Tibetan plateau are evolutionarily distinct; (5) North America <it>Leymus </it>species might originate from colonization via the Bering land bridge; (6) <it>Leymus </it>originated about 11-12MYA in Eurasia, and adaptive radiation might have occurred in <it>Leymus </it>during the period of 3.7-4.3 MYA and 1.7-2.1 MYA.</p> <p>Conclusion</p> <p><it>Leymus </it>species have allopolyploid origin. It is hypothesized that the adaptive radiation of <it>Leymus </it>species might have been triggered by the recent upliftings of the Qinghai-Tibetan plateau and subsequent climatic oscillations. Adaptive radiation may have promoted the rapid speciation, as well as the fixation of unique morphological characters in <it>Leymus</it>. Our results shed new light on our understanding of the origin of Xm genome, the polyploidization events and evolutionary history of <it>Leymus </it>that could account for the rich diversity and ecological adaptation of <it>Leymus </it>species.</p

Genetic characterization, species differentiation and detection of Fasciola spp. by molecular approaches

Liver flukes belonging to the genus Fasciola are among the causes of foodborne diseases of parasitic etiology. These parasites cause significant public health problems and substantial economic losses to the livestock industry. Therefore, it is important to definitively characterize the Fasciola species. Current phenotypic techniques fail to reflect the full extent of the diversity of Fasciola spp. In this respect, the use of molecular techniques to identify and differentiate Fasciola spp. offer considerable advantages. The advent of a variety of molecular genetic techniques also provides a powerful method to elucidate many aspects of Fasciola biology, epidemiology, and genetics. However, the discriminatory power of these molecular methods varies, as does the speed and ease of performance and cost. There is a need for the development of new methods to identify the mechanisms underpinning the origin and maintenance of genetic variation within and among Fasciola populations. The increasing application of the current and new methods will yield a much improved understanding of Fasciola epidemiology and evolution as well as more effective means of parasite control. Herein, we provide an overview of the molecular techniques that are being used for the genetic characterization, detection and genotyping of Fasciola spp.