Molecular and phylogenetic characterization of honey bee viruses, Nosema microsporidia, protozoan parasites, and parasitic mites in China

China has the largest number of managed honey bee colonies, which produce the highest quantity of honey and royal jelly in the world; however, the presence of honey bee pathogens and parasites has never been rigorously identified in Chinese apiaries. We thus conducted a molecular survey of honey bee RNA viruses, Nosema microsporidia, protozoan parasites, and tracheal mites associated with nonnative Apis mellifera ligustica and native Apis cerana cerana colonies in China. We found the presence of black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV), Israeli acute paralysis virus (IAPV), and sacbrood virus (SBV), but not that of acute bee paralysis virus (ABPV) or Kashmir bee virus (KBV). DWV was the most prevalent in the tested samples. Phylogenies of Chinese viral isolates demonstrated that genetically heterogeneous populations of BQCV, CBPV, DWV, and A. cerana-infecting SBV, and relatively homogenous populations of IAPV and A. meliifera-infecting new strain of SBV with single origins, are spread in Chinese apiaries. Similar to previous observations in many countries, Nosema ceranae, but not Nosema apis, was prevalent in the tested samples. Crithidia mellificae, but not Apicystis bombi was found in five samples, including one A. c. cerana colony, demonstrating that C. mellificae is capable of infecting multiple honey bee species. Based on kinetoplast-encoded cytochrome b sequences, the C. mellificae isolate from A. c. cerana represents a novel haplotype with 19 nucleotide differences from the Chinese and Japanese isolates from A. m. ligustica. This suggests that A. c. cerana is the native host for this specific haplotype. The tracheal mite, Acarapis woodi, was detected in one A. m. ligustica colony. Our results demonstrate that honey bee RNA viruses, N. ceranae, C. mellificae, and tracheal mites are present in Chinese apiaries, and some might be originated from native Asian honey bees

Development of Forest Engineering in China — Looking Ahead Ten Years

This paper highlights the development and prediction of forest engineering and forest engineering education in China. The activities of forest engineering has changed significantly since the introduction of a market economy into China. Profitability and economic efficiency are emphasized. Techniques and education systems in forest engineering must not be transferred mechanically from other countries. They must match existing social, economic, and physical conditions. The importance of forests in supplying non-wood forest products such as water and soil protection, climate adjustment, honey, nuts, mushrooms, medical plants and wildlife need to be considered when decisions are made about forest engineering activities, such as forest harvesting. Forest operations, as an important part of integrated forestry, should be planned from the point of view of sustainability of both timber and non-timber forest products. It is evident that a concerted effort is needed to encourage forest development programs that harmonize interests in conserving forests as well as to wisely use the potential of the forest while maintaining its full regeneration capacity. All forest engineering activities, such as forest resource surveying and harvesting planning, forest road planning and construction, harvesting , post-harvesting site disposal, planting and protection and so on should serve the key purpose of sustainable forestry. In view of the forest quality decline in China, it is essential that forest engineering practices are carried out in a manner to guarantee the sustainability of the forest resources base. "The Natural Forest Protection Project”, just started in 1998 in China brings challenges and changes to forest engineering. The environmentally sound, low cost and high efficient techniques of forest engineering will be the spotlight of research in the future

MULTIMEDIA QUESTION ANSWERING AND CONTENT-BASED PRODUCT ANNOTATION AND SEARCH

Ph.DDOCTOR OF PHILOSOPH

Inorganic hierarchical nanostructures induced by concentration difference and gradient

A very simple strategy for preparing hierarchical inorganic nanostructures under ambient aqueous conditions is presented. The hierarchical inorganic nanomaterials were obtained by simply adding a highly concentrated solution of one reactant to a solution of another reactant with low concentration. No surface-capping molecules or structure-directing templates were needed. The preparation of hierarchical single crystalline PbMoO(4) was used as an example in order to study the effects of varying the reaction conditions and the mechanism of the process. It was found that the large concentration difference (typically in excess of 200-fold) and the concentration gradient of the reactants both play key roles in controlling the diffusion process and the morphology of the resulting nanostructures. This kinetically controlled strategy is facile and is easily adapted to prepare a variety of inorganic materials.Chemistry, PhysicalNanoscience & NanotechnologyMaterials Science, MultidisciplinaryPhysics, AppliedSCI(E)0ARTICLE3213-220

TRPA1 Channels in Drosophila and Honey Bee Ectoparasitic Mites Share Heat Sensitivity and Temperature-Related Physiological Functions

The transient receptor potential cation channel, subfamily A, member 1 (TRPA1) is conserved between many arthropods, and in some has been shown to function as a chemosensor for noxious compounds. Activation of arthropod TRPA1 channels by temperature fluctuations has been tested in only a few insect species, and all of them were shown to be activated by heat. The recent identification of chemosensitive TRPA1 channels from two honey bee ectoparasitic mite species (VdTRPA1 and TmTRPA1) have provided an opportunity to study the temperature-dependent activation and the temperature-associated physiological functions of TRPA1 channels in non-insect arthropods. We found that both mite TRPA1 channels are heat sensitive and capable of rescuing the temperature-related behavioral defects of a Drosophila melanogaster trpA1 mutant. These results suggest that heat-sensitivity of TRPA1 could be conserved between many arthropods despite its amino acid sequence diversity. Nevertheless, the ankyrin repeats (ARs) 6 and 7 are well-conserved between six heat-sensitive arthropod TRPA1 channels and have critical roles for the heat activation of VdTRPA1

Nonlinear resonance of trapped waves on a plane beach

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2007.Includes bibliographical references (p. 307-310).Linear edge waves were first found mathematically by Stokes (1846). It has long been a topic of interest, since edge waves are believed to be responsible for the formation of beach cusps. Galvin (1965) was the first to observe in the laboratory that edge wave mode of frequency w can be excited by incident waves of frequency w. Guza and Bowen (1976) gave a theoretical explanation of the nonlinear mechanism of sub-harmonic resonance. This type of theory has been extended by Minzoni & Whitham (1977), Rockliff (1978), and Rockliff & Smith (1985), among others. Rockliff also initiated a. theory whereby subharmonic resonance can be achieved by an incident wave of frequency w, which leads to second harmonic at the second order to excite the edge wave. Their theory was however incomplete. The goal of this thesis is to extend the existing theories in order to show other paths to resonance. The nearshore region is a plane beach of small slope. For all cases we shall derive the evolution equations governing the edge wave amplitudes and analyze the stability of the equilibrium (static or dynamic) state. We first study in Chapter 2 synchronous resonance as a special case. We shall show that interaction between the edge wave and the incident/reflected wave also generates circulation cells on the beach.(cont.) Comparison is made between our theoretical results and the experiments by Bowen & Inman. We then give a corrected version of the work of Rockliff and Rockliff & Smith. Next, in Chapter 3 we generalize the idea of Chapter 2 and examine the excitation of an edge wave by a pair of incident waves of magnitudes comparable to the saturated edge wave but the sum of their frequencies can cause subharmonic resonance nonlinearly. In the development of theory, singularities were discovered at certain incident wave frequencies, each of which coincides with the difference of natural frequencies of two edge wave modes. Hence lower-order resonance happens. To remove this singularity we consider in Chapter 4 the simultaneous excitation of two modes of edge waves by one incident wave. The two edge waves are shown to be coupled by both linear and nonlinear terms. Instead of a fixed point, the dynamical system has two limit cycles as dynamic equilibria. Nonlinear numerical simulation and linear instability are analyzed.by Guangda Li.Ph.D

Topology Optimization Methods for Flexure Hinge Type Piezoelectric Actuators

Piezoelectric actuators have the obvious advantages of simple and compact structure, high precision and long stroke. However, it is difficult to satisfy the various industrial requirements. Topology optimization method can be used to find the new configurations of the compliant mechanism, and different objective function and constraint conditions can be flexibly used to determine the compliant mechanism. In the research of piezoelectric actuators, due to the advantages of compact structure, no lubrication and large displacement magnification, compliant mechanism is extremely suitable to be introduced into the design of piezoelectric actuators. In recent years, topology optimization method is frequently used to design the compliant mechanism on piezoelectric actuator, and has become a research hotspot. In this chapter, the development of topology optimization method is introduced, the design and research on the compliant mechanism of piezoelectric actuator have been summarized, and the future research direction and challenges of topology optimization design for flexure hinge type piezoelectric actuators are prospected

The Asymmetric Flexure Hinge Structures and the Hybrid Excitation Methods for Piezoelectric Stick-Slip Actuators

Piezoelectric stick–slip actuators have become viable candidates for precise positioning and precise metering due to simple structure and long stroke. To improve the performances of the piezoelectric stick–slip actuators, our team deeply studies the actuators from both structural designs and driving methods. In terms of structural designs, the trapezoid-type, asymmetrical flexure hinges and mode conversion piezoelectric stick–slip actuators are proposed to improve the velocity and load based on the asymmetric structure; besides, a piezoelectric stick–slip actuator with a coupled asymmetrical flexure hinge mechanism is also developed to achieve the bidirectional motion. In terms of driving methods, a non-resonant mode smooth driving method (SDM) based on ultrasonic friction reduction is first proposed to restrain the backward motion during the rapid contraction stage. Then, a resonant mode SDM is further developed to improve the output performance of the piezoelectric stick–slip actuator. On this basis, the low voltage and symmetry of the SDM are also discussed. Finally, the direction-guidance hybrid method (DGHM) excitation method is presented to achieve superior performance, especially for high speed

Variation of soil bacterial communities along a chronosequence of Eucalyptus plantation

Eucalyptus is harvested for wood and fiber production in many tropical and sub-tropical habitats globally. Plantation has been controversial because of its influence on the surrounding environment, however, the influence of massive Eucalyptus planting on soil microbial communities is unclear. Here we applied high-throughput sequencing of the 16S rRNA gene to assess the microbial community composition and diversity of planting chronosequences, involving two, five and ten years of Eucalyptus plantation, comparing to that of secondary-forest in South China. We found that significant changes in the composition of soil bacteria occurred when the forests were converted from secondary-forest to Eucalyptus. The bacterial community structure was clearly distinct from control and five year samples after Eucalyptus was grown for 2 and 10 years, highlighting the influence of this plantation on local soil microbial communities. These groupings indicated a cycle of impact (2 and 10 year plantations) and low impact (5-year plantations) in this chronosequence of Eucalyptus plantation. Community patterns were underpinned by shifts in soil properties such as pH and phosphorus concentration. Concurrently, key soil taxonomic groups such as Actinobacteria showed abundance shifts, increasing in impacted plantations and decreasing in low impacted samples. Shifts in taxonomy were reflected in a shift in metabolic potential, including pathways for nutrient cycles such as carbon fixation, which changed in abundance over time following Eucalyptus plantation. Combined these results confirm that Eucalyptus plantation can change the community structure and diversity of soil microorganisms with strong implications for land-management and maintaining the health of these ecosystems