The rights of children: public policy statement

Children, who are vulnerable at the start of existence, are a concern shared by nations and cultures. The importance of children's conditions has led 192 out of 194 countries to ratify the UN General Assembly's Convention on the Rights of the Child. The United States has not yet ratified the convention, despite having exercised influence on the drafting of its provisions. Given the global importance of nurturing and protecting children, the Society for Medical Anthropology strongly and emphatically supports that the convention be ratified, and that the U.S. government submit the convention for approval by the U.S. Senate.     

Reassessing Breeding Investment in Birds: Class-Wide Analysis of Clutch Volume Reveals a Single Outlying Family

Reproductive investment is typically considered in terms of size and number of propagules produced. Compared with a thorough understanding of the overall patterns and ecological correlates of avian clutch size, egg size has received less attention and the total effort invested in laying a clutch of eggs is rarely considered. We used clutch volume as an alternative estimate of reproductive investment and present the first class-level analysis of clutch volume in birds using 1,364 randomly-selected species in 204 families. The relationship between body mass and egg volume was very strong (r² = 0.946), validating previous studies identifying four families (Apterygidae, Pelecanoidiididae, Sternidae and Dromadidiae) with disproportionately large eggs. Clutch volume was also closely related to body mass (r² = 0.909) and all but one of the taxa with disproportionately large eggs conformed to the overall relationship, their greater egg dimensions compensated by diminished clutch size. The only family which departed significantly from the relationship between body mass and clutch volume was the mound builders (Megapodiidae)—the only group of birds that do not rely on body heat for incubation. Although previously known for laying large clutches of large eggs containing disproportionately large yolks, the remarkable investment of megapodes in reproduction (more than seven times greater than other birds of comparable mass) has been hitherto overlooked. We consider the evolutionary basis and ecological implications of this finding, suggesting that energetic costs associated with incubation act as an upper limit on reproductive output of other birds. We recommend clutch volume as a sensitive, fine-grained measure of reproductive effort for research at a wide range of scales and advocate further analysis of ecological correlates of clutch volume in birds and amniotes generally.     

ZSM-5(38)/Al-MCM-41复合分子筛对纤维素催化热解的影响

以纤维素为原料,以自制的不同硅铝比ZSM-5(38)/Al-MCM-41微-介孔复合分子筛为催化剂,在固定床反应器上进行了催化热解实验。采用XRD表征分子筛,采用GC-MS分析生物油成分,考查了催化剂的改变对生物质热解产物及生物油成分的影响。实验结果表明:添加催化剂后,生物油产率降低,且其含水率也有所增加。与未添加催化剂相比,生物油中D L-2,3-丁二醇有明显提高。其中,ZSM-5(38)/Al-MCM-41(20)最有利于苯酚、愈创木酚(2-甲氧基-苯酚)的生成。此外,这几种催化剂均有利于小分子化合物的生成,其中,ZSM-5(38)有利于C4~C5化合物的生成,微-介孔复合分子筛则有利于C6~C8化合物的生成。     

The electronic properties of poly(p-phenylenevinylene) derivatives and their monomers and oligomers

The electronic structures of monomers, oligomers and polymers of poly(p-phenylenevinylene) (PPV) derivatives are calculated and analysed based on density functional theory (DFT) methods. The influences of different substituent groups on the band gaps are discussed. Strong relationships are found between band-gap and bond length alternation (BLA) of polymers, and between band-gap and Wiberg bond index (WBI). Analysis of nuclear independent chemical shift (NICS) reveals that oligomers with similar energy gaps have close values of NICS.     

向日葵胰蛋白酶抑制剂SFTI-1

向日葵胰蛋白酶抑制剂(sunflower trypsininhibitor-1,SFTI-1)是近来发现的Bowman-Birk抑制剂(Bowman-Birk inhibitor,BBI)家族的新成员。由14个氨基酸残基组成的SFTI-1是具有胰蛋白酶抑制活性的天然环肽。SFTI-1的天然环状结构使它成为药物研发中的重要前导化合物。本文综述了近年来SFTI-1在结构、功能、环化机制等方面的研究进展。     

Invasive Haemophilus influenzae type b infections in vaccinated and unvaccinated children in Canada, 2001–2003

Background

Although vaccination of infants against Haemophilus influenzae type b (Hib) invasive infections is effective and has been routinely available in Canada since 1992, cases of the disease continue to occur. We were interested in determining whether recent cases of Hib infection reflected progressive loss of protection with time since vaccination, increasing nonacceptance of vaccination or a deleterious effect of coadministration of recently introduced vaccines such as those for pneumococcal and meningococcal conjugates and hepatitis B. We report on the causes of Hib infections among vaccinated and unvaccinated children between 2001 and 2003 in Canada.

Methods

Through our established network of 12 pediatric tertiary care hospitals we actively searched for cases in each centre by reviewing daily admissions and laboratory reports, visiting the wards and checking discharge diagnosis codes. Culture-confirmed cases were summarized by nurse monitors using a standardized reporting system.

Results

We identified 29 cases during the 3 years: 16 in 2001, 10 in 2002 and 3 in 2003. Half of the 29 patients had meningitis. Hib infection was more common among children less than 6 months of age (11 cases) and in boys (20 cases). Two deaths occurred (7% case-fatality ratio). A total of 20 children had received no or incomplete primary vaccination because of parental refusal (7 cases), because they were too young to have completed the primary series (11 cases, including 1 in which parental refusal was also a factor) or because of delays in completing the primary series (2 cases); the vaccination history was uncertain in the remaining case. Infection despite primary vaccination occurred in 9 children: 2 previously healthy children and 7 who were immunocompromised or who had a predisposing condition. None of the cases identified in 2003 involved children who had received any of the newly introduced vaccines.

Interpretation

Invasive Hib infections remain rare in Canada, with most cases occurring in children too young to have completed the primary series. Protection after vaccination appears to extend into later childhood and does not appear to be diminished by coadministration of newer infant vaccines.Until recently Haemophilus influenzae type b (Hib) was a leading cause of meningitis, epiglottitis and other invasive infections in children, affecting about 1 child in 250 by 5 years of age.¹ The risk of infection was highest among children 6–24 months of age. Antibodies directed against the Hib capsular polysaccharide (polyribosyl ribitol phosphate, PRP) form the basis of protection. PRP protein conjugate vaccines that elicit anti-PRP responses in young infants have been used in Canada since 1992. Doses are recommended at 2, 4 and 6 months of age to establish protection and at 18 months to reinforce it. Since 1995 all provinces have used the same Hib vaccine (a PRP–tetanus protein conjugate [PRP-T], produced by Aventis Pasteur), in combination products based on whole-cell pertussis vaccines (from 1995 to 1997) or acellular pertussis vaccines (1998 to the present).Invasive Hib infections have been monitored since 1992 by a network of Canadian pediatric hospitals known as the Immunization Monitoring Program, Active (IMPACT).² In 1985, before the first Hib vaccine was licensed, 485 invasive Hib cases were seen at 10 centres (those participating in IMPACT when the “look-back” was done).³ Case totals fell progressively as better vaccines became available.^3,4,5 In 2000, only 4 cases were recorded by the IMPACT centres (which by then numbered 12), 99% fewer than in 1985.⁶ Continuing surveillance is important to assess the effectiveness of the current schedule and vaccine. Because Hib vaccination is relatively new, the question of duration of protection remains open. Resurgence of Hib disease occurred recently in the United Kingdom,⁷ prompting addition of a booster dose to the vaccination schedule (as in Canada). Other questions of relevance are whether nonacceptance of Hib vaccine is influencing case totals and whether coadministration of newer vaccines, such as those for pneumococcal and meningococcal group C conjugates and hepatitis B, is adversely affecting Hib responses. A reduced response is most likely to occur when infants are given conjugate vaccines containing the same carrier protein,⁸ which is not the case with PRP-T and pneumococcal conjugate vaccines; however, their compatibility has not been formally demonstrated to date. In this report we present details of cases encountered by IMPACT in the period 2001 to 2003.