Optical trapping and manipulation of viruses and bacteria

Optical trapping and manipulation of viruses and bacteria by laser radiation pressure were demonstrated with single-beam gradient traps. Individual tobacco mosaic viruses and dense oriented arrays of viruses were trapped in aqueous solution with no apparent damage using approximately 120 milliwatts of argon laser power. Trapping and manipulation of single live motile bacteria and Escherichia coli bacteria were also demonstrated in a high-resolution microscope at powers of a few milliwatts.     

Visibility of single atoms

Theoretical and experimental studies indicate that, with a high-resolution scanning electron microscope, it is now possible to obtain pictures of a single heavy atom resting on a thin carbon substrate.     

Multiphoton ionization of atoms

Studies of multiphoton ionization of atoms have revealed several unexpected characteristics. The confluence of the experimental evidence leads to the hypothesis that the basic character of the atomic response involves highly organized, coherent motions of entire atomic shells. The important regime, for which the radiative field strength is greater than an atomic unit (e/a(2)(0)), can be viewed in approximate correspondence with the physics of fast (approximately 10 MeV per atomic mass unit) atom-atom scattering. This physical picture provides a basis for the expectation that stimulated emission in the x-ray range can be produced by direct, highly nonlinear coupling of ultraviolet radiation to atoms.     

Coherence with atoms

The past decade has seen dramatic progress in our ability to manipulate and coherently control the motion of atoms. This progress has both fundamental and applied importance. On the one hand, recent experiments are providing new perspectives for the study of quantum phase transitions and highly entangled quantum states. On the other hand, this exquisite control offers the prospect of a new generation of force sensors of unprecedented sensitivity and accuracy.     

Genetic manipulation of antibiotic-producing microorganisms

The application of directed selection techniques and genetic engineering methods for manipulation of antibiotic-producing microorganisms is generating a new era in industrial microbiology. Modern methods, based on advances in the knowledge of the biosynthetic pathways and regulatory mechanisms involved in the induction and repression of genes involved in antibiotic synthesis, provide a means of increasing antibiotic activity. Hence, recombinant DNA and protoplast fusion methods are used to alter the genetics of antibiotic producers in a semirandom fashion for the development of novel hybrid antibiotics. Directed mutation and selection, protoplast fusion, and both semirandom and specific recombinant DNA methods are examples of alternative procedures for manipulating the biosynthetic pathways of microorganisms for strain improvement and for new hybrid antibiotic synthesis.     

Creation and manipulation of three-dimensional optically trapped structures

An interferometric pattern between two annular laser beams is used to construct three-dimensional (3D) trapped structures within an optical tweezers setup. In addition to being fully translatable in three dimensions, the trapped structure can be rotated controllably and continuously by introducing a frequency difference between the two laser beams. These interference patterns could play an important role in the creation of extended 3D crystalline structures.     

Impact of genetic manipulation on society and medicine

Human beings have been manipulating the genetic characteristics plants and animals since the introduction of agriculture indirect manipulation of human genes occurred with widespread use of public health and medical measures that preserve genes causing disease. The production of biologicals by DNA technology raises few ethical problems. Predictive medicine in which genetic markers (including DNA variants) are used for antenatal and preclinical diagnosis of genetic diseases and susceptibilities poses new questions of confidentiality, private versus societal goals, and self-determination. When normal DNA is used to treat the somatic cells of patients with hemoglobinopathies and other genetic diseases, no new ethical problems arise beyond those presented by an novel theory. In contrast, manipulation of DNA in human fertilized eggs would constitute a qualitative departure from previous therapies since this would affect future generations. In order to be able to make wise decisions on these matters the public must be well informed. Thus, formal and informal education in human biology and genetics must be improved at all levels.     

Sex ratio manipulation and selection for attractiveness

Laboratory experiments performed on a monogamous estrildid, the zebra finch (Poephila guttata), indicate that sex ratio of offspring is affected by non-genetic markers (colored plastic leg bands) that vary in attractiveness to birds. Results suggest that natural selection favors individuals that produce offspring of the sex of the more attractive parent within a breeding pair.     

Growth of body weight and manipulation of food motivation

Consideration was given to the possible use of individual growth curves to estimate ad libitum-feeding weights as part of technique for producing specified degrees of food deprivation. In heterozygous animals, this possibility was found to be feasible but limited by the occurrence of discontinuous growth functions.     

Cooling, stopping, and trapping atoms

Significant advances have been made in the ability to control the motion of neutral atoms. Cooling and trapping atoms present new possibilities for studies of ultracold atoms and atomic interactions. The techniques of laser cooling and deceleration of atomic beams, magnetic and laser trapping of neutral atoms, and a number of recent advances in the use of radiative forces to manipulate atoms are reviewed.     

罗非鱼染色体组操作研究现状与展望

罗非鱼属鲈形目(Perciformes),丽鱼科(Cichlidae),约有700种,主要分布于非洲。按照Trewavas[1]分类法,可把罗非鱼分为3个属,即Tilapia属、Sarotherodon属和Oreochromis属。目前,有生产应用价值的主要是Oreochromis属的尼罗罗非鱼(O.niloticus)、奥利亚罗非鱼(O.aureus)以及莫桑比克罗非鱼(O.mossambicus)[2]。罗非鱼具有生长快、食性杂、繁殖快、产量高和味道鲜美而少刺等优良特征,近年来,全球罗非鱼养殖产量逐年递增,现已成为世界性主要养殖鱼类之一。这就迫使人们不断对养殖罗非鱼进行遗传改良,以防其种质退化。当前,国内外除了人工选…     

罗非鱼染色体组操作研究现状与展望

罗非鱼属鲈形目(Perciformes),丽鱼科(Cichlidae),约有700种,主要分布于非洲。按照Trewavas[1]分类法,可把罗非鱼分为3个属,即Tilapia属、Sarotherodon属和Oreochromis属。目前,有生产应用价值的主要是Oreochromis属的尼罗罗非鱼(O.niloticus)、奥利亚罗非鱼(O.aureus)以及莫桑比克罗非鱼(O.mossambicus)[2]。罗非鱼具有生长快、食性杂、繁殖快、产量高和味道鲜美而少刺等优良特征,近年来,全球罗非鱼养殖产量逐年递增,现已成为世界性主要养殖鱼类之一。这就迫使人们不断对养殖罗非鱼进行遗传改良,以防其种质退化。当前,国内外除了人工选…     

近红外激光云高仪与微脉冲激光雷达比对分析

云在气象领域扮演着重要的角色,因此准确测量云高有助于分析天气系统未来的变化,为气象等领域提供依据。为了比较CL51激光云高仪和微脉冲激光雷达(MPL)这2个云高仪的性能,对位于南京信息工程大学的2台仪器2012年9—11月这3个月的数据进行分析,得出如下结论:CL51和MPL第一层云底高度的相关性很高,相关系数为0.89;CL51的所有数据平均高度为3.879 km,MPL的所有数据平均高度为3.587 km,说明这2台仪器的一致性很高。