The development of personal space: Proxemic behavior of children 6 through 16

Observations were made of the personal space behaviors of same-sex pairs of children, aged 6–16. Results indicated that children used more space as they grew older and that adult proxemic behaviors were acquired by age 12. While in the younger children no sex differences were present for the proxemic behaviors of distance and body orientation, males were found by early adolescence to stand farther apart and at greater angles than females. The development of personal space and of sex differences in these behaviors is discussed in the context of social learning.     

A personal voyage through the proteoglycan field

The concept of “proteoglycans” as discrete molecules surfaced some 40 years ago, out of previously muddled notions of the extracellular matrix. Core proteins were gradually recognized as molecular entities, distinct with regard to location, substitution with glycosaminoglycan (GAG) chains and biological function. This development is surveyed, with brief outline of methodological approaches, biosynthesis, and functional aspects. Special emphasis is given to the impact of genomics on the field. Some outstanding unresolved issues are emphasized, including regulation of GAG biosynthesis and the specificity of GAG-protein interactions.     

生物学发展及其对人才素质的要求

21世纪生物学发展由单一走向综合,其巨大成就的取得需要复合型人才一在众多方面的人才素质中,最突出的是人的进取性和创新精神?其中思维活力及创造力是现代人才要素的核心：因此,学校必须由应试教育向素质教育转轨,培养具备两种态度(即积极学习和正确做人的态度)和两种能力(独立学习与表达交流的能力)的创新人才。     

Physicians' perception of personal risk of HIV infection and AIDS through occupational exposure.

Physicians'' response to acquired immune deficiency syndrome (AIDS) is poorly understood and often attributed to fear of human immunodeficiency virus (HIV) infection through occupational exposure. We surveyed 268 physicians from three geographic regions in North American with different specialties and responsibilities for HIV-positive patients. An important difference was found between the published risk and the physicians'' perceived risk of infection after a single occupational exposure. Almost half of the respondents stated that they feared contracting AIDS more than other diseases. The physicians who perceived themselves to be at high physical risk were more likely than the others to report that AIDS had changed the way they interact with their patients (r = 0.26, p less than 0.001). No relation was found between the perception of physical risk and the number of HIV-infected patients (r = -0.07, p = 0.15). However, the perception of social risk showed a small inverse correlation (r = -0.15, p less than 0.02), in which the physicians with more HIV-infected patients reported less concern about negative social consequences. The physicians who perceived themselves to be at high personal risk were more likely than the others to report that surgeons have the right to refuse patients who do not wish to undergo HIV antibody testing (r = -0.16, p less than 0.01 for physical risk; r = -0.29, p less than 0.001 for social risk). Multiple regression analyses indicated that physicians'' perception of physical risk was not related to age or sex but was modestly related to income source. The perception of social risk was related to sex and income source. Physicians'' perception of personal risk is a crucial, yet often unacknowledged, component of the fight against AIDS. Our findings suggest that lack of attention to this issue is seriously compromising initiatives designed to facilitate physician participation in AIDS care.     

Investigating C. elegans development through mosaic analysis

The analysis of genetically mosaic worms, in which some cells carry a wild-type gene and others are homozygous mutant, can reveal where in the animal a gene acts to prevent the appearance of a mutant phenotype. In this primer article, we describe how Caenorhabditis elegans genetic mosaics are generated, identified and analyzed, and we discuss examples in which the analysis of mosaic worms has provided important information about the development of this organism.     

Mandela restores morale of AIDS conference

During the 13th international AIDS conference in Durban, former president Nelson Mandela pulled the morale of the conference highlighting the need to confront the needs and concerns of those suffering and dying of HIV/AIDS in South Africa, mostly in sub-Saharan. He also stated that to challenge the grave threat posed by HIV and AIDS, efforts should be combined to save the people. This concluding remark was in direct contrast to the opening words of South Africa's current president, Thabo Mbeki, who failed to deal with the impression he has created internationally that he has doubts about the etiology of AIDS. In addition, the need to focus on the accessibility and affordability of treatment for HIV/AIDS or the opportunistic infections associated with it was highlighted. The conference focused on this issue with the help of AIDS activists, who emphasized that pharmaceutical companies needed to address how their drugs could reach those who most need them.     

Cortical development and remapping through spike timing-dependent plasticity.

Long-term modification of synaptic efficacy can depend on the timing of pre- and postsynaptic action potentials. In model studies, such spike timing-dependent plasticity (STDP) introduces the desirable features of competition among synapses and regulation of postsynaptic firing characteristics. STDP strengthens synapses that receive correlated input, which can lead to the formation of stimulus-selective columns and the development, refinement, and maintenance of selectivity maps in network models. The temporal asymmetry of STDP suppresses strong destabilizing self-excitatory loops and allows a group of neurons that become selective early in development to direct other neurons to become similarly selective. STDP, acting alone without further hypothetical global constraints or additional forms of plasticity, can also reproduce the remapping seen in adult cortex following afferent lesions.     

Cell cycling through development

Regardless of the species, the development of a multicellular organism requires the precise execution of essential developmental processes including patterning, growth, proliferation and differentiation. The cell cycle, in addition to its role as coordinator of DNA replication and mitosis, is also a coordinator of developmental processes, and is a target of developmental signaling pathways. Perhaps because of its central role during development, the cell cycle mechanism, its regulation and its effects on developing tissues is remarkably complex. It was in this light that the Keystone meeting on the cell cycle and development at Snowbird, Utah in January 2004 was held.     

Gradual development of protein-like global structures through functional selection.

This work focuses on streamlining the exploration of all possible sequences in an attempt to find polypeptides capable of folding into unique structures. Using a computer simulation, we have demonstrated the efficacy of constraining an 'active site' toward the correct configuration, in this case a particular conformation of a four-residue sequence, to bring about protein-like structure from a significant fraction of random sequences. The successive selections for a correct local configuration lead also to the gradual development of overall folding ability, helicity and compactness within 200 generations. The selection thus imposed alleviates an exhaustive search in sequence space.