THE RATE OF SENESCENCE OF THE DOMESTIC FOWL AS MEASURED BY THE DECLINE IN EGG PRODUCTION WITH AGE

Data are presented showing that the course of decline of egg production with age in the domestic fowl from the time laying begins up to and including 8 years follows an exponential law, that is, each year''s egg production is a constant percentage of the preceding year''s production (88 per cent in the group of fowl studied). Since the exponential law is the same as the law of monomolecular change in chemistry, and since the course of egg production with age may be taken as an index of the course of senescence of organs, or tissues limiting egg production, it is suggested that this exponential law of egg production substantiates the idea that senescence is a physicochemical process the course of which is limited by a chemical reaction. It is shown that the exhaustion of the oocytes is not likely to be the factor limiting the course of egg production.     

Relating annual increments of the endangered Blanding's turtle plastron growth to climate

This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross‐date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross‐dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration.     

Traumatic vasospastic disease in chain-saw operators.

Raynaud''s phenomenon is commonly induced in chain-saw operators by vibration; the hand guiding the tool is the more severely affected. The condition tends to persist after use of the chain-saw is stopped but compensation is rarely sought. Among 17 cases of Raynaud''s phenomenon in lumberjacks the condition was found to be related to use of the chain-saw in 14, 10 of whom had to give up their work in colder weather because the disease was so disabling. Two criteria essential to establish the condition as vibration-induced Raynaud''s phenomenon are the presence of symptoms for at least 2 years and a history of at least 1 year''s constant use of the chain-saw. Careful physical examination and simple tests of vascular function will provide objective evidence of permanent damage by which the patients may be classified and compensated.     

Molecular graphics abstract

This year's annual meeting of the Molecular Graphics Society was held at the University of Surrey in Guildford, UK, over the weekend of 10–12 April 1987. Below is an abstract of one paper presented at the meeting. The rest were published in the June 1987 issue.     

内蒙古森林火灾发生风险及其驱动因素

森林火灾是危害森林健康的主要灾害之一,科学预测森林火灾是预防森林火灾的重要依据。以中国新旧森林火灾政策作为分界线,将内蒙古森林历史火灾数据分为四个阶段,基于增强回归树模型建立内蒙古森林火灾发生模型,预测森林火灾发生情况,解释不同时期森林火灾和火灾风险变化的差异。预测结果表明:(1)4个时期建模精度AUC均大于0.94,表明BRT模型能够较好地预测研究区森林火灾的发生;(2)气温日较差、日最小相对湿度、上一年春防累计降水量、上一年秋防累计降水量、上一年春防最高地表气温海拔、距火点最近公路距离被确定为影响内蒙古森林火灾发生的重要驱动因素。(3)新旧《森林防火条例》实施前后森林火灾风险等级变化:1981-1988年3月14日,中、高和极高森林火灾风险区分布在呼伦贝尔的东部,而2009-2020年中、高和极高森林火灾风险区分布在呼伦贝尔南部和中部、赤峰市的西南部、锡林郭勒盟和呼和浩特市的中部、乌兰察布市和包头市的南部以及鄂尔多斯市的东部。有助于了解不同时期《森林防火条例》影响下的内蒙古森林火灾的驱动因素和火险等级的变化,为优化森林火灾管理政策及预测预报工作提供科学依据。     

Biological education—starting from the real world

A report by Georgina Morrison on one of this year's WATCH projects     

The role of brain scanning in the differential diagnosis of seizures

Of 200 patients with seizures who had brain scans, the studies were abnormal in 86% of patients with tumours and in 67% of those with strokes. The scan detected 84% of the 19 potentially curable lesions. There were no false positive studies. Seventy-nine per cent of patients with seizures of less than one year''s duration had an abnormal scan; however, the scan was also abnormal in 22% of patients with non-focal seizures of less than one year''s duration.     

Taking the brakes off-are IC foundries in the industry's best interest?

Following up last issue's editorial topic, GaAs evangelism, another prime driving factor for the IC industry is the need for more design freedom. Before any new technology can be taken up, there must be enough engineers out there versed in the methodology. This obvious statement begs the question: where does this knowledge come from? Most noticeably from the IC foundries who are, for the most part, keen to restrict the spread of this knowledge outside their “club” of users. Is this in the best interest of progress in the GaAs industry as a whole?     

Will operate for food.

After spending 15 years in university, Dr. Robert Patterson recently received the right to write FRCSC after his name, and then began to look for gainful employment as a general surgeon. It was a long and frustrating search. He recounts how he finally found work in northern Alberta, and wonders if next year''s residents will encounter the same shortage of opportunities that he discovered.     

Community psychiatry and the elderly

An account is given of the first year''s experience in providing psychogeriatric service to a large urban community. Patients were attended in their homes, in nursing homes and in Homes for the Aged. There was a tendency for the consultant''s help to be sought mainly in cases of “disposal” of difficult patients rather than for treatment of the many who could be expected to benefit from it. However, the advantage has been demonstrated of continuity of service in the variety of settings and, as a result, the more proper placement of patients. Acceptance of the help the psychogeriatrician can contribute will inevitably increase, but demands the provision of improved day-care and day-hospital facilities.     

The Drosophilidae (Diptera) of the Scattered Islands,with the description of a novel association with Leptadenia madagascariensis Decne. (Apocynaceae)

The 10th CanFly (Canadian Drosophila Research Conference) meeting took place June 1-4, 2009 in Jasper National Park, west of Edmonton. This year's meeting has over 100 participants representing over 30 different research groups from every region of Canada, as well as several groups from the United States and Europe. Topics included ranged from Cell Biology, Signaling and Adhesion to Development, Gene Regulation and Neurobiology.     

The effects of enhanced ozone and enhanced carbon dioxide concentrations on biomass, pigments and antioxidative enzymes in spruce needles (Picea abies L.)

During one growing period, 5-year-old spruce trees (Picea abies L., Karst.) were exposed in environmental chambers to elevated concentrations of carbon dioxide (750 cm³ m^?3) and ozone (008 cm³ m^?3) as single variables or in combination. Control concentrations of the gases were 350cm³ m^?3CO₂ and 0.02 cm³ m ^?3 ozone. To investigate whether an elevated CO₂ concentration can prevent adverse ozone effects by reducing oxidative stress, the activities of the protective enzymes superoxide dismutase, catalase and peroxidase were determined. Furthermore, shoot biomass, pigment and protein contents of two needle age classes were investigated. Ozone caused pigment reduction and visible injury in the previous year's needles and growth reduction in the current year's shoots. In the presence of elevated concentrations of ozone and CO₂, growth reduction in the current year's shoots was prevented, but emergence of visible damage in the previous year's needles was only delayed and pigment reduction was still found. Elevated concentrations of ozone or CO₂ as single variables caused a significant reduction in the activities of superoxide dismutase and catalase in the current year's needles. Minimum activities of superoxide dismutase and catalase and decreased peroxidase activities were found in both needle age classes from spruce trees grown at enhanced concentrations of both CO₂ and ozone. These results suggest a reduced tolerance to oxidative stress in spruce trees under conditions of elevated concentrations of both CO₂ and ozone.     

Effects of elevated CO2, elevated O3 and potassium deficiency on Norway spruce [Picea abies (L) Karst.]: seasonal changes in photosynthesis and non-structural carbohydrate content

Two clones of 5-year-old Norway spruce [Picea abies (L.) Karst.] were exposed to two atmospheric concentrations of CO2 (350 and 750 μmol mol^?1) and O₃ (20 and 75nmolmol^?1) in a phytotron at the GSF-Forschung-szentrum (Munich) over the course of a single season (April to October). The phytotron was programmed to recreate an artificial climate similar to that at a high elevation site in the Inner Bavarian Forest, and trees were grown in large containers of forest soil fertilized to achieve contrasting levels of potassium nutrition, designated well-fertilized or K-deficient. Measurements of the rate of net CO₂ assimilation were made on individual needle year age classes over the course of the season, chlorophyll fluorescence kinetics were recorded after approximately 23 weeks, and seasonal changes in non-structural carbohydrate composition of the current year's foliage were monitored. Ozone was found to have contrasting effects on the rate of net CO₂ assimilation in different needle age classes. After c. 5 months of fumigation, elevated O₃ increased (by 33%) the rate of photosynthesis in the current year's needles. However, O3 depressed (by 30%) the photo-synthetic rate of the previous year's needles throughout the period of exposure. Chlorophyll fluorescence measurements indicated that changes in photosystem II electron transport played no significant role in the effects of O₃ on photosynthesis. The reasons for the contrasting effects of O₃ on needles of different ages are discussed in the light of other recent findings. Although O₃ enhanced the rate at which CO₂ was fixed in the current year's foliage, this was not reflected in increases in the non-structural carbohydrate content of the needles. The transfer of ambient CO₂-grown trees to a CO₂-enriched atmosphere resulted in marked stimulation in the photosynthetic rate of current and previous year's foliage. However, following expansion of the current year's growth, the photosynthetic rate of the previous year's foliage declined. The extent of photosynthetic adjustment in response to prolonged exposure to elevated CO₂ depended upon the clone, providing evidence of intraspecific variation in the long-term response of photosynthesis to elevated CO₂. The increase in photosynthesis induced by CO₂ enrichment was associated with increased foliar concentrations of glucose, fructose and starch (but no change in sucrose) in the new growth. CO₂ enrichment significantly enhanced the photosynthetic rate of K-deficient needles, but there was a strong CO₂soil interaction in the current year's needles, indicating that the long-term response of trees to a high CO₂ environment may depend on soil fertility. Although the rate of photosynthesis and non-structural carbohydrate content of the new needles were increased in O₃-treated plants grown at higher levels of CO₂, there was no evidence that elevated CO₂ provided additional protection against O₃ damage. Simultaneous exposure to elevated O₃ modified the effects of elevated CO₂ on needle photosynthesis and non-structural carbohydrate content, emphasizing the need to take into account not only soil nutrient status but also the impact of concurrent increases in photochemical oxidant pollution in any serious consideration of the effects of climate change on plant production.     

PAIR FORMATION AND PAIR MAINTENANCE IN THE REDSHANK TRINGA TOTANUS

The percentage (45.6%) of colour-marked Redshanks which return to Banks Marsh NNR retain the pair from the previous year. whilst 6.9% of the previous year's pairs separate and take new mates. In 29.8%, of the previous year's pairs only the male returns and in 17.7%, only the female returns. Usually pairs are established by the male performing a display flight and pair maintenance is facilitated by means of an alighting ceremony. Two main peaks occur in the performance of these displays which are associated with two physiological groups within the population. early and late breeders.     

Community participation in primary health care.

A two and a half year''s experience of a community participation group has shown that this can have a valuable role in suggesting practicable improvements in a group practice. Topics discussed by the group (which is composed of one representative from every known organization in the area) have included problems of receptionists; the role of the individual ancillary worker; and teaching in general practice. The high attendance rate at the group''s meetings testifies to the community''s interest in primary health care services.     

Biology and Television

The paper deals with the problem of designing a teacher's guide which will encourage and assist a teacher to arrive at well-reasoned independent decisions, and respect the teacher's experience and intellectual autonomy. The method described pertains to independently developed materials, not developed for any particular curriculum or teaching approach, thus leaving decisions about their adoption and adaptation to the teacher. A representative sample of teachers was used to obtain feedback information before, during, and after teaching a newly developed laboratory block in genetics for the 11th–12th grade level (17–18 year olds). Questionnaire and interview methods were used. Twelve categories for possible inclusion in the teacher's guide emerged. Decisions on whether to include a category in the teacher's guide were shown to be based on the teachers' manifest degree of familiarity with it, their measure of (or lack of) awareness of its educational potential, and their expressed desires for assistance.     

Treatment and Follow-up of Adolescents Addicted to Heroin

A survey of the first year''s referral of heroin-addicted adolescents was undertaken exactly two years after the opening of a special treatment unit. Out of 130 patients presenting 78 were selected for treatment and were followed up. The drug-taking pattern of this group is reported. At the time of the survey 27% were assessed as off all addictive drugs.     

The child's best interest in gamete donation

Procreation with donor gametes is widespread and commonly accepted, but it involves ethical questions about the child's best interest. Understanding the historical structures of the moral discussion of gamete donation may contribute to reflecting on the child's best interest. This is why I have analysed the debate on gamete donation in the Netherlands, and this analysis has uncovered some striking discontinuities. Notions of the child's best interest have undergone a radical swing. In the past, it was considered acceptable to conceal the truth about the child's biological origin, but in the past two decades the general opinion has changed to the common belief that this information should be shared with the child. This changed notion of the child's best interest will be analysed using a framework encompassing three views of the child, which derive from the debate on children's rights. These three views each provide a different interpretation of the child's moral and political status. I conclude that the changed notion of the child's best interest results from a view of the child that focuses on autonomy and citizenship, and which frames the child's interests according to its legal status. I comment on this view and I champion an alternative one, namely ‘the embedded child’. This is a relational view based on care ethics that goes beyond what can be articulated in law, and that will help to establish a more balanced interpretation of the child's best interest at the practice and policy levels of gamete donation.     

Spatio-temporal variation in a seed bank of a semi-arid region in northeastern Brazil

This study aimed to evaluate variations in the seed bank within a 3-year temporal series in order to answer the following questions: 1) Does the seed bank's species richness and seed density differ among climatic seasons and between years? 2) Are there differences in the richness and density of seed banks between the litter and mineral soil? 3) Can the seed bank's species richness and seed density be explained by characteristics such as the previous year's precipitation and soil depth (litter or mineral soil)? The samples were collected from litter and mineral soil (0–5 cm), in 210 sub-plots, during the dry and rainy seasons of each year (August 2005 through February 2008). Overall, 79 species were recorded. On average, 1 168, 304 and 302 seeds.m⁻² were recorded in the seed bank during years I, II and III, respectively. This study showed that the Caatinga's seed bank is rich in herbaceous species, yet species' density and richness are low in the litter. Furthermore, about 43% of the variation in species richness and density was explained by soil depth (litter and mineral soil) and previous years' rainfall.