bluuebunny/crossref_metadata_2025 huggingface dataset:
Is targeted early detection for melanoma feasible? Self assessments of risk and attitudes to screening
Authors: Eiser J.R. , Pendry L. , Greaves C.J. , Melia J. , Harland C. , Moss S.
Published: October 2002

Objectives To study the feasibility of developing targeted screening for those at high risk of melanoma by examining how attitudes relate to (a) acceptance of an invitation for a free skin check and (b) self assessed and clinically assessed risk factors for developing cutaneous melanoma.

Design A population based cross sectional survey.

Setting A general practice with a broad mix of socioeconomic groups in one district health authority.

Subjects A total of 1600 subjects aged 25–69 years stratified using the social deprivation score of wards were randomly selected from a population of 8000; 77% (1227) returned the questionnaire and 56% (896) attended for screening.

Main outcome measuresQuestionnaire measures of confidence in own ability to self assess risk factors for melanoma, attitudes to seeking medical help for skin abnormalities, and self assessment of relative risk of developing melanoma.

Results Clinic attenders were less confident in their ability to self assess risk factors (p<0.005), more favourable towards seeking help (p<0.001), and more pessimistic about developing melanoma (p<0.001) than non-attenders. Those from more affluent wards were more willing to seek help (p<0.001). Those clinically assessed as at higher risk were more pessimistic about developing melanoma (p<0.001) but clinical assessments were inconsistently related to help seeking attitudes and self assessment confidence.

Conclusions Barriers to the uptake of screening included greater optimism about not developing melanoma, confidence in self assessment, and reluctance to seek professional help. Such reluctance was greater in more deprived social groups. Targeting screening at high risk groups cannot depend on self identification and self referral.
Results from 10 years of breast screening in Wales
Authors: Fielder H. , Rogers C. , Gower-Thomas K. , Monypenny I. , Dallimore N. , Brook D. , Greening S.
Published: October 2002

Objective To present results from 10 years of breast screening in Wales, including rates of interval cancers.

Setting All women aged 50–64 years in Wales; approximately 250 000 in each screening round.

Methods Breast Test Wales (BTW) began mammographic screening in 1989 as part of the National Breast Screening Programme. Two view mammography was introduced at the inception of the Welsh programme for all prevalent screens. Single view mammography was subsequently performed for incident screens. Interval cancers were identified by matching details from the BTW administrative screening database with the BTW database of all incident breast cancers for residents in Wales.

Results For the first and second round prevalent screens, the cancer detection rate was 8.6 per 1000 and 7.4 per 1000 screened, respectively. The interval cancer rates following round one were 4.9 per 10 000 in the first 12 months, 9.0 per 10 000 between 12 and 24 months, and 11.6 per 10 000 between 24 and 36 months after screening. For the second round incident screens the detection rate was 4.6 per 1000 and the standardised detection ratio was 0.89, but the interval cancer rates in the first year after incident screens were not statistically different from those following prevalent screens. There was no change in the proportion of invasive breast cancers which were <15 mm in diameter, or in the grades of invasive cancer between the first and second rounds, prevalent or incident screens.

Conclusions Breast Test Wales has achieved the standards set by the National Health Service Breast Screening Programme. Taking two views at the prevalent screen gave high sensitivity and may have resulted in the low standardised detection ratio at subsequent incident screens.
Monitoring and evaluating the UK National Health Service Breast Screening Programme: evaluating the variation in radiological performance between individual programmes using PPV-referral diagrams
Authors: Blanks R.G. , Moss S.M. , Wallis M.G.
Published: October 2002

A high quality breast cancer screening programme can be defined as one offering both a high cancer detection rate and a low referral rate of women for further investigation. Such a programme will have as few women as possible undergoing further investigations who do not have a final diagnosis of breast cancer—that is, a high positive predictive value of referral for further investigation. This paper introduces a graphical technique to illustrate individual programme performance. The graph plots positive predictive value of referral against referral rate, with the cancer detection rate expressed as “isobars” on the graph. Confidence limits can be expressed as “boxes” on the diagram. The graph not only illustrates programme performance but also enables suggestions to be made to improve performance. The definition of high quality screening is seen to have a subjective element as well as an objective element, as radiologists have to balance screening sensitivity with specificity. The technique is illustrated using data from the individual screening programmes in the UK National Health Service Breast Screening Programme for the screening year 1 April 1998 to 31 March 1999. The methodology could also be applied to other national screening programmes.
Strategy linking several analytical methods of neonatal screening for sickle cell disease
Authors: Ducrocq R. , Pascaud O. , Bévier A. , Finet C. , Benkerrou M. , Elion J.
Published: October 2002

Background The French national programme for the neonatal screening of sickle cell disease (SCD) was set up in 1995. This screening is targeted at newborn infants at risk. Over 5 years, 115 480 newborn infants were tested from 80 maternity departments from the northern part of the Paris area. 250 Patients with SCD were identified— that is, one in 462 newborn infants tested. Carriers for a haemoglobin (Hb) variant are frequent (5.34%). Some uncommon Hb variants were also identified, which gave rise to pitfalls to the testing when associated with HbS: HbKorle-Bu, HbHope, HbBougardirey-Mali, and HbLadésirade (4% of SS-like profiles).

Objective An effective screening strategy was developed to avoid these false positive and false negative responses.

Methods Isoelectric focusing (IEF), the method of primary screening, is rapid and inexpensive. Cation exchange high performance liquid chromatography (CE-HPLC), which is automated, fast, and quantitative was selected as a secondary method.

Results IEF diagnosed normal profiles in 89% of the tested samples from newborn infants. CE-HPLC identified most of the common Hb variants by their retention time and the measure of HbA/HbS ratio, important for the differential diagnosis between an asymptomatic HbS carrier and an HbS/&bgr;+thal compound heterozygote. Furthermore, the high sensitivity of the CE-HPLC detected as little as 0.5% of a Hb variant. This avoided false negatives in samples from premature or transfused newborn infants. All samples with SS-like profiles were confirmed with a second CE-HPLC with another programme. A combination of these three methods confirmed the status of 99.7% of the samples from the tested newborn infants. Some cases required a reverse phase-HPLC method (for &ggr;-globin or &agr;-globin chain variants). Finally, some exceptional samples required confirmation by testing DNA extracted with Güthrie paper for a precise diagnosis.

Conclusions This effective strategy combining several methods dramatically reduces the risk of errors. Many families are thus spared unnecessary worrying recalls. The only unavoidable cause of false positives remains the HbS/hereditary fetal Hb (HPFH).
Detecting which invasive cancers at mammographic screening saves lives?
Authors: Evans A.J. , Pinder S.E. , Burrell H.C. , Ellis I.O. , Wilson A.R.M.
Published: October 2002

Objectives Assessment of the features of primary operable breast carcinomas arising in women known to subsequently develop metastatic disease, to show for which invasive breast cancers earlier detection by mammographic screening is potentially beneficial. These data were applied to a separate series of screen detected cancers.

Methods Features associated with the development of metastatic disease after a previous operable breast cancer were ascertained from examination of histological sections of the initial primary carcinoma and in particular the incidence of nodal positivity and definite vascular invasion. Trends in the frequency of nodal involvement and vascular invasion according to histological grade, invasive size, and tumour type were then examined in a further group of 573 screen detected invasive cancers to predict the likelihood of development of systemic disease in these women.

Results Of 173 women who developed metastatic disease after a previous operable breast cancer, 79 (72%) had nodal metastases and 62 (59%) had definite vascular invasion. A high proportion (84%) had either lymph node metastases or vascular invasion or both. The absence of vascular invasion and nodal involvement in invasive breast cancer indicated a low risk of subsequent development of metastatic disease. In the screen detected group, grade 1 invasive cancers <20 mm in size and grade 2 and 3 cancers <10 mm in size had low rates of nodal involvement and vascular invasion. There was a gradual trend to small size, lymph node negativity, and less vascular invasion when comparing screen detected ductal carcinoma of no special type, tubular mixed carcinoma, and tubular carcinoma. Cancers with a lobular component tended to be larger and more often lymph node positive than ductal and no specific type carcinomas.

Conclusions These data suggest that identification of grade 1 cancers less than 20 mm in size and grade 2 and 3 cancers less than 10 mm in size at screening is likely to be beneficial, with a lower likelihood of developing metastatic disease from these lesions. The detection of tubular mixed carcinomas and ductal carcinomas of no specific type also appears beneficial. However the detection of tumours with lobular features at breast screening does not seem to significantly benefit the patient.
Screening and the number needed to treat
Authors: Richardson A.
Published: October 2002

OBJECTIVE:To develop a measure analogous to the "number needed to treat" (NNT), which would be appropriate for population based screening programmes. METHODS:A previous measure analogous to the NNT, the "number needed to screen" (NNS), calculated as the reciprocal of the absolute risk reduction, does not account for participation and selection effects in screening trials. A new measure is proposed; the NNBS (number needed to be screened) derived from the NNT adjusted for participation in screening and for selection effects associated with participation in screening. The NNBS for breast cancer screening and colorectal cancer screening are calculated, based on the results of randomised controlled trials. RESULTS:In the first 8 years from the start of each screening programme, the NNS to prevent one death from breast cancer was 781 women (95% confidence interval (95% CI) 550 to 1560). The NNS to prevent one death from colorectal cancer was 1250 people (95% CI 690 to 9090). The NNBS was 23% lower than the NNS for breast cancer screening (NNBS=601), and 45% lower than the NNS for colorectal cancer (NNBS=688). CONCLUSIONS:The NNT calculations may make population based screening programmes seem expensive and inefficient compared with other interventions. A new measure, the number needed to be screened (NNBS), which takes into account the participation rate adjusted for selection, may be more appropriate, especially when comparing screening programmes with disparate participation rates, or when comparing screening with other interventions.
Second trimester screening for Down's syndrome: 7 years experience
Authors: Beaman J.M. , Goldie D.J.
Published: October 2002

OBJECTIVES:To evaluate the effectiveness of the first 7 years of a programme for second trimester antenatal screening for Down's syndrome, using α-fetoprotein (αFP) and total human chorionic gonadotropin (hCG) as maternal serum markers. METHODS:A clinical biochemistry laboratory providing a screening service for four obstetric units. Women attending for antenatal care who accepted an offer of serum screening for Down's syndrome were tested between 15 and 20 weeks gestation. Down's risk estimates were calculated using maternal serum αFP and total hCG results as modifiers of the maternal age related risk. Outcome was determined in collaboration with the regional cytogenetics unit. RESULTS:In 7 years 66 631 women were screened, in whom 108 Down's syndrome pregnancies were identified. Risks for Down's syndrome were reported without a specified cut off recommendation; however, at a cut off of 1 in 250, 72 (66.7%) of the affected pregnancies were screen positive, the false positive rate was 5.8%, and the uptake of amniocentesis 71.2%. The detection rate was higher in women screened before 17 weeks (70.5%) than in those screened at 17 weeks or later (56.7% overall and 20.0% in those under 30 years). The uptake of screening declined gradually from 84% in 1992 to 59.5% in 1998. CONCLUSIONS:Two marker screening using αFP and total hCG is an effective way of screening for Down's syndrome and is widely accepted in the local community. Detection rates were comparable with other second trimester studies using two markers including both total and free βhCG.
Anxiety in a cohort of Swiss women participating in a mammographic screening programme
Authors: Meystre-Agustoni G. , Paccaud F. , Jeannin A. , Dubois-Arber F.
Published: October 2002

OBJECTIVES:To follow up anxiety in a cohort of women screened for breast cancer. METHODS:Within the framework of a pilot screening programme for breast cancer in the Canton of Vaud (Switzerland), a cohort of 924 participants aged 50–70 years were invited to answer questions on anxiety related to mammography screening. Anxiety was measured using a specific tool, the psychological consequences questionnaire (PCQ), and a new single item, direct question, breast cancer anxiety indicator (BCA). Participants were asked to fill in the questionnaire at four different phases: at screening, before the result, and 2 and 8 weeks after the result. The final response rate was 93.7%. Predictors of anxiety at each phase were assessed using multiple regression. RESULTS:Among those screening negative (94.7%), anxiety at screening was very low and remained so during the screening process. Among those screening false positive, anxiety was significantly higher 8 weeks after having received a negative diagnosis. Predictors of anxiety before screening were lower education and higher age, with a strong exogenous anxiety component. For subsequent phases, the initial anxiety score and education were the main determinants. Furthermore, a false positive result at screening was the most important predictor of anxiety 2 months after negative diagnosis. Anxiety measured with the BCA was strongly correlated with the PCQ. CONCLUSION:Anxiety was very low at screening and remained so during the process for negative women. Initial anxiety level was a strong predictor of anxiety during the entire process, up to 8 weeks after a negative result, and could be easily assessed using the BCA. The sustained higher anxiety level among those screening false positive is an undesirable side effect of the programme.
Impact of antenatal HIV screening to prevent HIV infection in children in Norway 1987–99
Authors: Aavitsland P. , Nilsen Ø. , Lystad A. , Bjørndal A.
Published: October 2002

OBJECTIVE: To assess the impact of the antenatal HIV screening programme in Norway in preventing HIV infection in children. SETTING: Norway, 1987–99. METHODS: In a simulated retrospective cohort design data were used from the mandatory HIV surveillance system to compare the observed number of children born infected with HIV in Norway 1987–99 to the expected number without the antenatal screening programme. The main measures were relative and absolute performance of the screening programme. Other measures were uptake and false positive rate of screening, and number and exposure category of screen positive women. RESULTS: 96% of 961 000 eligible pregnant women were tested. 0.1% had an indeterminate test result and 46 women (5.0/100 000) were confirmed screen positive. 27 were African or south east Asian women infected before immigration to Norway. Nine out of 739 000 live born children (1.2/100 000) were infected compared with the expected 18 with no screening. The absolute impact of the screening programme was 1.3 (95% confidence interval (95% CI) -0.1 to 2.7) prevented infections in 100 000 women screened. The relative preventive impact was 51% (-15% to 81%). CONCLUSIONS: The limited absolute impact is because of the very low prevalence of undetected HIV infection among pregnant women in Norway.
Predictors of outcome of mammography in the National Health Service Breast Screening Programme
Authors: Banks E. , Reeves G. , Beral V. , Bull D. , Crossley B. , Simmonds M. , Hilton E. , Bailey S. , Barrett N. , Briers P. , English R. , Jackson A. , Kutt E. , Lavelle J. , Rockall L. , Wallis M.G. , Wilson M.
Published: October 2002

BACKGROUND: Little is known about the factors influencing the risk of recall for assessment, invasive diagnostic procedures, and early rescreening after screening mammography. METHODS: From June 1996 to March 1998 women attending screening at 10 National Health Service Breast Screening Programme (NHSBSP) centres completed a self administered questionnaire and were followed up for their screening outcome. RESULTS: 1969 (3.3%) out of 60 443 women aged 50–64 who had never used hormone replacement therapy (HRT) were recalled for assessment but were not diagnosed with breast cancer (defined here as false positive recall). After adjustment for the variation between centres, false positive recall was decreased significantly among women who were likely to have had a previous NHSBSP mammogram (odds ratio (OR) 0.49, 95% confidence interval (95% CI) 0.38 to 0.63 for likely versus unlikely), who were postmenopausal (OR 0.65, 95% CI 0.56 to 0.76 for postmenopausal v premenopausal) and increased significantly for women reporting previous breast surgery (OR 1.64, 95% CI 1.42 to 1.89). Although false positive recall decreased significantly with parity and increasing body mass index, these effects were not large and no significant variation was found with age, education, family history of breast cancer, oral contraceptive use, sterilisation, exercise, smoking, or alcohol consumption. Altogether 655 (1.1%) women had an invasive diagnostic procedure; no personal characteristics were predictive of this outcome, 286(0.5%) were referred for early rescreening, and this was increased significantly by nulliparity and a family history of breast cancer. INTERPRETATION: Premenopausal women, those without a previous NHSBSP mammogram, and women with previous breast surgery have an increased risk of false positive recall by the NHSBSP.
Do mental disorders matter? A study of absenteeism among care seeking Gulf War veterans with ill defined conditions and musculoskeletal disorders
Authors: Dremsa T L , Engel C C , Liu X , Johantgen M , Smith S
Published: October 2002

Aims:To investigate the extent that common psychological conditions contribute to lost work among individuals with musculoskeletal and ill defined conditions.

Methods:Cross sectional health and work related survey evaluating Gulf War veterans seeking Department of Defense health care for Gulf War related health concerns. Ordered probit models were used to study whether a provider diagnosed musculoskeletal condition (ICD-9 codes 710–739) or “signs, symptoms, and ill defined conditions” (ICD-9 codes 780–799) have an effect on recent lost work over the previous 90 days in the presence of one or more psychological conditions (ICD-9 codes 290–320) after controlling for sociodemographic variables.

Results:Bivariate analyses revealed that musculoskeletal conditions, ill defined conditions, and psychological conditions were positively associated with lost work. Multivariate analyses showed an independent effect of both psychological conditions and musculoskeletal conditions. A significant interaction existed between psychological conditions and musculoskeletal conditions: the presence of a coexisting psychological condition considerably increased the likelihood that a musculoskeletal disorder resulted in lost work, or vice versa.

Conclusions:Psychological conditions appear to be an important contributor to absenteeism among individuals with musculoskeletal and ill defined conditions. A limitation of the cross sectional design was the inability to sequence the onset of conditions.
Prevention of work related skin problems: an intervention study in wet work employees
Authors: Held E , Mygind K , Wolff C , Gyntelberg F , Agner T
Published: October 2002

Aims:To evaluate the effect of implementation of an evidence based skin care programme for wet work employees as part of an occupational health and safety management system.

Methods:375 wet work employees were included in a prospective randomised controlled trial, allocated to either intervention (n = 207) or control (n = 168). The intervention group was exposed to a skin care programme during the five month study period. The intervention included an educational programme for a group of frontline employees, who underwent formalised training, and subsequently introduced the information to their colleagues. As part of the intervention a skin care policy including written instructions was established at each workplace. Both groups answered a test quiz, completed questionnaires on behaviour and symptoms, and underwent clinical examination of their hands before and after the five month period.

Results:No difference between the intervention and the control group was found at baseline with respect to clinical symptoms or behaviour. Evaluation after the five months of intervention revealed a significantly higher information level on skin care in the intervention group compared to the control group, a significant change in behaviour in the intervention group but not in the control group, and significantly less skin symptoms as evaluated clinically in the intervention group but not in the control group. No significant difference was found for self reported skin problems.

Conclusions:The intervention was successful with respect to information level (knowledge), behaviour, and clinical symptoms. Implementation of a skin care programme as part of an occupational health and safety management system is recommended as a prophylactic measure for employees in wet occupations.
Anthocyanins of jack pine (Pinus banksiana) seedlings
Authors: Nozzolillo Constance , Isabelle Pierre , Andersen Øyvind M , Abou-Zaid Mamdouh
Published: October 2002

Purpling of the needles of jack pine seedlings in forest tree nurseries in the autumn is a result of the production of at least five anthocyanin pigments: cyanidin 3-O-glucoside (~80%), delphinidin 3-O-glucoside (~8%), peonidin 3-O-glucoside (~8%), petunidin 3-O-glucoside (~3%) and malvidin 3-O-glucoside (trace). The twigs subtending the needles also produce a similar range of pigments. The entire spectrum of pigments is produced from the time of the first exposure to freezing temperatures. Proanthocyanidins are a prominent feature of the needle phenolics and the question of their possible involvement in the purpling phenomenon following exposure to sub-zero temperatures is raised. The red colour of the hypocotyl of the newly germinated seedling is also a result of a similar mixture of pigments.Key words: Pinus banksiana, Pinaceae, jack pine seedlings, anthocyanin pigmentation, hypocotyl, proanthocyanidins.
Relationship between chlorophyll a fluorescence induction and oxygen evolution in barley (Hordeum vulgare) thylakoids treated with alpha-, beta-, and gamma-cyclodextrins
Authors: Sridharan G , Daneau E , Fragata M
Published: October 2002

Cyclodextrins, a class of cyclic oligomeric compounds consisting of 68 units of D-glucose, alter the oxygen evolution of photosystem II (PSII) in barley thylakoids as well as chlorophyll a fluorescence induction, i.e., Fv/Fo and Fv/Fm where Fm is the maximal level of fluorescence when all PSII centres are closed, Fo is the minimal level of chlorophyll fluorescence when all PSII centres are open, and Fv is the variable fluorescence (= Fm  Fo). The highest Fv/Fm and Fv/Fo values are observed in samples treated with alpha- and beta-cyclodextrins, i.e., 0.618 and 0.629 (Fv/Fm) and 1.617 and 1.667 (Fv/Fo), respectively, whereas in untreated and gamma-cyclodextrin-treated thylakoids, one observes 0.608 and 0.594 (Fv/Fm) and 1.568 and 1.460 (Fv/Fo). This trend is also seen in the oxygen evolution of control and alpha-, beta-, and gamma-cyclodextrin-treated thylakoids, i.e., 183.6, 214.9, 301.7, and 174.0 µmol O2·mg chlorophyll1·h1, respectively. First, the fluorescence induction data indicate that in intact thylakoid membranes, the enhancement of oxygen evolution induced by alpha- and beta-cyclodextrins originates in the opening of blocked photochemical centres in PSII. Second, the results show that the correlation between the oxygen evolution of PSII and chlorophyll a fluorescence induction is a nonlinear phenomenon represented by a Boltzman expression.Key words: chlorophyll, cyclodextrins, fluorescence induction, oxygen evolution, photosystem II, thylakoid membrane.
Morphological and isozyme variation in Cerastium arvense (Caryophyllaceae) in the southern Andes
Authors: Quiroga María Paula , Premoli Andrea C , Ezcurra Cecilia
Published: October 2002

We tested the hypothesis that South Andean populations of the highly polymorphic and mostly Northern Hemisphere perennial forb Cerastium arvense L. show ecotypic variation along distinct habitats. We compared differences in morphology and flowering phenology among six natural populations occurring in different environments. Genetic differences were analyzed by a common-garden experiment and isozyme electrophoresis. Several of the morphological differences observed in the field were maintained after more than a year of cultivation in the common garden (e.g., plant height and leaf width). Mean tests and multivariate analyses on morphological traits generally distinguished high-elevation populations from the rest, and a similar grouping of populations was obtained from isozyme data at 10 loci. Cerastium arvense had genetic polymorphism levels of >50% in all populations and an average genetic diversity (HT = 0.254) of which approximately 20% was distributed among populations. These marked genetic differences are probably maintained by restricted gene flow due to variation in flowering time. Morphological and genetic differences suggest ecotypic variation in C. arvense in the southern Andes, which seems to have originated by disruptive selective pressures in different environments and the effect of genetic drift in response to the extreme climatic changes occurring during the Pleistocene.Key words: common-garden experiment, ecotypic variation, elevation and precipitation, genetic diversity, Patagonian Andes, phenology.
NOTEAspects of floral development in Caladium bicolor (Araceae)
Authors: Barabé Denis , Lacroix Christian
Published: October 2002

In the spadix of Caladium, there is a clearly recognizable intermediate zone consisting of sterile male flowers. The transition between the female zone and the male sterile zone is more or less abrupt. During the early stages of development of the inflorescence, a few atypical bisexual flowers between the female zone and the male sterile zone are recognizable. These atypical flowers display a variety of forms. However, in all cases, the staminate portion of the flower is located near the male zone and the gynoecial portion near the female zone. The undeveloped synandroidral portion and the rudimentary gynoecium belong to the same meristematic unit and can be viewed as a single whorl. The early stages of development of atypical bisexual flowers in Caladium and Philodendron are relatively similar and therefore represent an intermediate form between female and male sterile flowers.Key words: inflorescence, homeosis, gradient, flower.
In vitro antagonism of Botrytis cinerea by phylloplane yeasts
Authors: Buck James W
Published: October 2002

The influence of inoculum and nutrient concentrations on the in vitro antagonism of Botrytis cinerea by phylloplane yeasts was investigated with detached leaf disk and conidial germination assays. Rhodosporidium toruloides Y-1091 significantly reduced lesion development after 96 h on geranium leaf disks when co-inoculated at 1 × 106 or 1 × 107 yeast cells/mL with B. cinerea conidia at 1 × 104 or 1 × 105 conidia/mL. No effect on lesion development was observed when yeast and fungus were co-inoculated at a 1:1 ratio. Biocontrol activity of R. toruloides was greatest in 20 mM glucose and 20-fold dilute yeast nitrogen base. Twenty-five phylloplane yeasts exhibited a wide range of biocontrol activity when screened for antagonism of B. cinerea on geranium leaf disks (1 × 106 yeast cells/mL, 1 × 105 conidia/mL). Lesion development was significantly reduced by yeasts initially identified as poor antagonists when inoculated at higher concentrations (5 × 106 or 1 × 107 yeast cells/mL) with B. cinerea. Both poor and good antagonists significantly reduced in vitro germination of B. cinerea conidia. The presence of B. cinerea conidia had a greater effect on the growth of two poor antagonists compared with two good antagonists on leaf disks. These data suggest that many phylloplane yeasts will antagonize B. cinerea under conditions of low nutrient availability and with high antagonist to pathogen ratios.Key words: yeast, biological control, competition, nutrients, germination, Rhodosporidium toruloides.
Chemostratigraphy of the Neoproterozoic Alona Bay lavas, Ontario
Authors: Walker James A , Gmitro Todd T , Berg Jonathan H
Published: October 2002

A basal sequence of flood basalt lavas associated with the Neoproterozoic Midcontinent rift system crops out in Alona Bay along the southeastern shore of Lake Superior in Ontario. The Alona Bay lava succession is about 1200 m thick and lies just north of the well-studied, contemporaneous Mamainse Point Formation. Detailed chemostratigraphy of the Alona Bay lavas suggests they are grossly correlative with the basal portion of the Mamainse Point Formation. For instance, like the basal part of Mamainse Point Formation, the Alona Bay section contains numerous high-MgO lavas and can be subdivided into 45 groups with distinct chemical characteristics. Chemical variations within the Alona Bay groups are largely the result of fractional crystallization, likely at moderate pressures. One small group of Alona Bay lavas also carries the compositional imprint of crustal contamination. The remaining inter-group chemical distinctions at Alona Bay are the consequence of temporal changes in partial melting and source character. With time and development of the Midcontinent rift, degrees of melting increased; mean pressures of melting decreased, reducing garnet control; and lithospheric source contributions waned. Similar temporal variations during flood basalt evolution have been documented elsewhere.
Relay Mountain Group, TyaughtonMethow basin, southwest British Columbia: a major Middle Jurassic to Early Cretaceous terrane overlap assemblage
Authors: Umhoefer Paul J , Schiarizza Paul , Robinson Matt
Published: October 2002

The upper Middle Jurassic to Lower Cretaceous Relay Mountain Group is the lower part of the northern TyaughtonMethow basin, southwestern British Columbia. The Relay Mountain Group consists of ~27003400 m of clastic rocks that we subdivide into three formal formations. The Callovian and lower Oxfordian Tyoax Pass Formation is marine shale and sandstone turbidites. The Teepee Mountain Formation consists of upper Oxfordian to Valanginian shallow marine clastic rocks with common Buchia and fluvial and marginal marine facies in the upper part of the unit in the northwest. These rocks overlie the lower formation across an abrupt conformable to disconformable contact. The Hauterivian (and Barremian?) Potato Range Formation consists of clastic rocks that are marine in the southeast, mainly nonmarine to the northwest, and derived from the west. This unit displays an abrupt conformable to disconformable contact with the middle formation and locally rests above the lower formation across an angular unconformity. The Relay Mountain Group and correlative strata of the southeastern Coast Belt form an overlap assemblage above the Bridge River and Cadwallader (including Methow) terranes and link them by late Middle Jurassic time. The early Relay Mountain Group appears to have been a fore-arc basin, possibly along an obliqueconvergent margin in the middle unit. The upper unit indicates major changes to a back-arc basin linked to the Ottarasko, and possibly Gambier, arc to the west. This is the oldest probable link (~130 Ma) between the southeastern and southwestern Coast belts.
Bleaching of color of kraft pulp mill effluents and natural organic matter in lakes
Authors: Vähätalo Anssi V , Salonen Kalevi , Saski Eija , Salkinoja-Salonen Mirja S
Published: October 2002

In situ changes in the color of lake water and biologically treated kraft pulp mill effluents mixed in lake water were examined in three lakes. In 1.7 m3 enclosures, the color (400700 g Pt·m3) of the mixture of pulp mill effluent and lake water remained similar for 4 months in darkness, whereas exposure to solar radiation resulted in 1742% bleaching of color. During the summer stratification of a humic lake, the color (160 g Pt·m3) of hypolimnetic water remained similar to that found during spring turnover, but the color of epilimnion decreased 13%. The measured rates of photochemical bleaching of color by solar radiation could explain the decrease of epilimnetic color. Attenuation of photobleaching in the water column was similar to that of blue irradiance. Measured photobleaching was well described by a model based on quantum yields. The model revealed that visible solar radiation accounted for 29% of photobleaching at the surface and 66% in the whole water column. The results indicated that solar radiation, rather than plankton, bleached color of lake water and pulp mill effluents in surface strata.
Measurement error and bias in the maximum reproductive rate for the Ricker model
Authors: Kehler Daniel G , Myers Ransom A , Field Christopher A
Published: October 2002

We investigated the consequences of measurement errors in spawner abundance on the estimation of alpha(tilde), the maximum lifetime reproductive rate, in the Ricker spawner-recruit model. This rate is equivalent to the slope at the origin for the Ricker model, which is crucial for the estimation of management reference points. Simulation results indicate that measurement error in spawner abundance does not lead, in general, to an overestimate of alpha(tilde), as had been previously thought. Instead, the direction, and to some extent the magnitude, of the bias is related to the range of spawner values, and we provide an analytical explanation for this phenomenon. For stocks that have been heavily exploited and have low spawner values, measurement error tends to result in an overestimate of log alpha(tilde), usually by [Formula: see text]5%. Less exploited stocks with large spawner values will have their log alpha(tilde) underestimated, commonly by 15 to 25%. Results from data-based simulations indicate that under certain conditions, empirical Bayes estimates for the distributions for alpha(tilde) among stocks, i.e., the prior distribution, can still be relatively unbiased in the presence of measurement error.
A 3D slope stability analysis method assuming parallel lines of intersection and differential straining of block contacts
Authors: Chang Muhsiung
Published: October 2002

A three-dimensional (3D) method of analysis of the stability of slopes was developed based on the sliding mechanism observed in the 1988 failure of the Kettleman Hills landfill slope (Kettleman City, California) and the associated model studies. By adopting a limit equilibrium concept, the method assumes the sliding mass as a block system in which the contacts between blocks are inclined. The lines of intersection of the block contacts are assumed to be parallel, which enables the sliding kinematics. In consideration of the differential straining between blocks, the shear stresses on the slip surface and the block contacts are evaluated based on the degree of shear strength mobilization on these contacts. The overall factor of safety is calculated based on the force equilibrium of the individual blocks and the entire block system as well. Based on comparisons with a series of hypothetical 3D and 2D problems with known solutions, the method was generally found to be accurate in predicting the stability of slopes involving a translational type of sliding failure. For rotational sliding failures in clays, however, the method appears to slightly overestimate the calculated factor of safety; up to as much as 10% in a typical problem examined in this study.Key words: slope stability, 3D method, limit equilibrium, block kinematics, strain incompatibility.
Are all MRSA made equal?
Authors: Cimolai Nevio
Published: October 2002

The health and economic burden of methicillin-resistant Staphylococcus aureus (MRSA) in the medical realm is considerable. Although there is ample clinical and laboratory evidence indicating that methicillin-susceptible S. aureus (MSSA) is heterogeneous in disease causation, the same heterogeneity has not been well documented for MRSA. Data from animal models and human studies suggest that MRSA is at least as pathogenic as MSSA. Many comparative clinical studies, mainly retrospective, have assessed the virulence of MSSA and MRSA. Whereas the majority of these studies may be deficient in some aspects of clinical design, there has been a definite trend towards implicating MRSA as the more aggressive pathogen. Such an observation, however, must be tempered with the fact that few such studies have attempted to establish clonality among MRSA isolates. Thus, it is conceivable that hypervirulent clones may represent an important proportion of MRSA from hospital studies where patient-patient spread is likely and, accordingly, comparative studies may be biased. Future clinical studies should be prospective and should use well-defined and homogeneous patient groups. As well, for comparison of MRSA and MSSA, an understanding of clonality is essential.Key words: Staphylococcus aureus, methicillin resistance, virulence, pathogenesis.
Comparing the carbon budgets of boreal and temperate deciduous forest stands
Authors: Barr A G , Griffis T J , Black T A , Lee X , Staebler R M , Fuentes J D , Chen Z , Morgenstern K
Published: October 2002

Boreal and temperate deciduous forests at northern mid-latitudes play an important role in the global carbon cycle. We analyze 3 years (1996-1998) of eddy-covariance carbon dioxide flux measurements from two contrasting deciduous forest ecosystems in the boreal and temperate regions of central Canada. The two forest stands have similar ages, heights, and leaf area indices but differ in species composition and climate. Mean annual net ecosystem productivity (NEP) was similar for the two ecosystems, varying between 0.7 and 2.7 t C·ha1 (boreal) and 0.6 and 2.4 t C·ha1 (temperate). In the boreal ecosystem, interannual differences in NEP were primarily controlled by early spring temperature. The warm spring of 1998 caused early leaf out and increased photosynthesis but had little effect on respiration. In the temperate ecosystem, the same warm spring not only caused early leaf out but also increased respiration and drought stress. The contrasting impact of the warm spring on annual NEP at the two sites illustrates the complexity of interpreting climatic impacts on the forest carbon balance. It also illustrates two competing influences of climate change on NEP: spring warming, which promotes photosynthesis and increases NEP, and increased soil temperature and drought, which promote respiration and reduce photosynthesis, thus reducing NEP. We discuss the need for a consistent data post-processing methodology in ecosystem intercomparisons. We also compare our results with a recent synthesis of data from European forests.
Simulated root freezing in the nursery: effects on the growth and physiology of containerized boreal conifer seedlings after outplanting
Authors: Dumais Daniel , Coursolle Carole , Bigras Francine J , Margolis Hank A
Published: October 2002

The effects of induced root freezing injury on 2+0 white spruce (Picea glauca (Moench) Voss), black spruce (Picea mariana (Mill.) BSP), and jack pine (Pinus banksiana Lamb.) seedlings were studied. Hardened seedlings were exposed to freezing during the fall and cold stored until planting. Seedlings were planted in spring on two field sites with different soil moisture levels (wet or dry). Seedling morphology and physiology were measured periodically during the first growing season, and mortality was evaluated at the end of the season. With the exception of June measurements on the wet site, where daytime water potential fell as low as 2.0 MPa, root damage did not seriously affect shoot water potential. Generally, stomatal conductance decreased with increasing root damage. Net photosynthesis on both sites decreased between 22 and 39% with increasing root damage. Root damage did not affect the ratio of intercellular to ambient CO2concentration. As well, reductions in the nitrogen concentration of current-year foliage with increasing root damage were observed, suggesting that the observed reductions in net photosynthesis were caused by nonstomatal factors. Root growth was greater on the wet site than on the dry site, particularly between August and October, when mean soil minimum temperatures were lower on the dry site. On both sites, aerial dry mass was only slightly affected by root damage in July and August, but the effect of damage became more pronounced in October on the wet site. Black spruce and white spruce seedling mortality began being affected when approximately 50% of the root systems were damaged, while jack pine mortality was affected starting at 40% damage. Root damage levels of 50% caused 2.0 and 1.5 cm reductions in annual height increment of white spruce and black spruce, respectively, and 40% damage caused a reduction of 1.0 cm in annual height increment of jack pine.
Reply - Effects of adventitious roots on age determination in balsam fir regeneration
Authors: Parent Sylvain , Morin Hubert
Published: October 2002

In many Canadian boreal forests, balsam fir (Abies balsamea (L.) Mill.) seedlings established under closed canopy generally develop adventitious roots. Adventitious roots induce the formation of a reverse taper, i.e., a reduction of the diameter and of the number of growth rings towards the true collar (hypocotyl region). Consequently, ring count at any level of the trunk underestimates the true age of firs, and we recommend a reassessment of balsam fir dynamics inferred from studies based on ages estimated by ring count. Recently, Kneeshaw and Claveau (D.D. Kneeshaw and Y. Claveau. 2001. Can. J. For. Res. 31: 1292-1295) presented data from a subsample of fir seedlings to demonstrate that ring count is an accurate aging technique for most fir regeneration. A careful examination of the methodology, data, and samples presented suggests that true collars were not precisely located. We also present data collected on seedlings sampled in the same study area as Kneeshaw and Claveau. Most of the seedlings (57 of 60 seedlings, <50 cm in height) had adventitious roots, and ring count was not an appropriate aging method. According to our study, Kneeshaw and Claveau either did not locate the true collar or presented atypical balsam fir seedlings.
CONSIDERATIONS ON SUPER POINCARÉ ALGEBRAS AND THEIR EXTENSIONS TO SIMPLE SUPERALGEBRAS
Authors: FERRARA S. , LLEDÓ M. A.
Published: October 2002

We consider simple superalgebras which are a supersymmetric extension of the spin algebra in the cases where the number of odd generators does not exceed 64. All of them contain a super Poincaré algebra as a contraction and another as a subalgebra. Because of the contraction property, some of these algebras can be interpreted as de Sitter or anti de Sitter superalgebras. However, the number of odd generators present in the contraction is not always minimal due to the different splitting properties of the spinor representations under a subalgebra. We consider the general case, with arbitrary dimension and signature, and examine in detail particular examples with physical implications in dimensions d = 10 and d = 4.
COCYCLE CONJUGACY OF ONE PARAMETER AUTOMORPHISM GROUPS OF AFD FACTORS OF TYPE III
Authors: HUI UN KIT
Published: October 2002

We classify, up to cocycle conjugacy, one-parameter automorphism groups on an approximately finite dimensional (AFD) factor ℳ of type III with trivial Connes spectrum. Our goal is to find the complete cocycle conjugacy invariants for one-parameter automorphism groups on ℳ. We also study the relations between the flow of weights of ℳ and that of the crossed product ℳ ⋊α ℝ of ℳ by a one-parameter automorphism group α with Γ(α) = {0}. Moreover, we also study model realizations. "Model realizations" means that given certain commutative data, they can be realized as the complete cocycle conjugacy invariants of centrally free and centrally ergodic one-parameter automorphism groups on some properly infinite AFD von Neumann algebras.
FRONT PROPAGATION IN RANDOM MEDIA: FROM EXTREMAL TO ACTIVATED DYNAMICS
Authors: SKOE RUNE , VANDEMBROUCQ DAMIEN , ROUX STÉPHANE
Published: October 2002

Front propagation in a random environment is studied close to the depinning threshold. At zero temperature we show that the depinning force distribution exhibits a universal behavior. This property is used to estimate the velocity of the front at very low temperature. We obtain a Arrhenius behavior with a prefactor depending on the temperature as a power law. These results are supported by numerical simulations.
WHAT CAN SNO NEUTRAL CURRENT RATE TEACH US ABOUT THE SOLAR NEUTRINO ANOMALY
Authors: BANDYOPADHYAY ABHIJIT , CHOUBEY SANDHYA , GOSWAMI SRUBABATI , ROY D. P.
Published: October 2002

We investigate how the anticipated neutral current rate from SNO will sharpen our understanding of the solar neutrino anomaly. Quantitative analyses are performed with representative values of this rate in the expected range of 0.8–1.2. This would provide a 5–10σ signal for νe transition into a state containing an active neutrino component. Assuming this state to be purely active one can estimate both the 8 B neutrino flux and the νe survival probability to a much higher precision than currently possible. Finally the measured value of the NC rate will have profound implications for the mass and mixing parameters of the solar neutrino oscillation solution.
LATTICE DIRAC FERMIONS IN A NON-ABELIAN RANDOM GAUGE POTENTIAL: MANY FLAVORS, CHIRAL SYMMETRY RESTORATION AND LOCALIZATION
Authors: ICHINOSE IKUO
Published: October 2002

In the previous paper we studied Dirac fermions in a non-Abelian random vector potential by using lattice supersymmetry. By the lattice regularization, the system of disordered Dirac fermions is defined without any ambiguities. We showed that at strong-disorder limit correlation function of the fermion local density of states decays algebraically at the band center. In this paper, we shall re-examine the multi-flavor or multi-species case rather in detail and argue that the correlator at the band center decays exponentially for the case of a large number of flavors. This means that a delocalization–localization phase transition occurs as the number of flavors is increased. This discussion is supported by the recent numerical studies on multi-flavor QCD at the strong-coupling limit, which shows that the phase structure of QCD drastically changes depending on the number of flavors. The above behavior of the correlator of the random Dirac fermions is closely related with how the chiral symmetry is realized in QCD.