Kentucky Bluegrass Floral Induction and Cultivar Response to Mechanical Removal of Harvest Residue

Open-field burning of post-harvest residue from Kentucky bluegrass (Poa pratensis L.) seed fields is being phased out in Washington, USA and may be banned in Idaho. Burning encourages early fall regrowth and timely completion of fall floral induction. Cultivars have different floral induction requirements and respond differently to mechanical residue removal. Our objective was to determine if length of fall floral induction requirement was related to seed yield when post-harvest residue was removed by crewcut vacuum sweeping. Floral induction requirements were not related to first-or second-year seed yields. Third-year seed yield of cultivars with long floral induction requirements declined more than third-year seed yields of cultivars with short floral induction requirements. Turf type, aggressive cultivars usually have longer floral induction requirements than non-aggressive cultivars. Exceptions suggest that turf type cultivars with short floral induction requirements can be developed. Cultivar selection will be important for sustained yields with mechanical residue removal

Preservice Teacher Preparation in International Contexts: A Case-Study Examination of the International Student Teacher Programs

This article examines the teacher preparation experiences of preservice teachers in six international contexts: China, Fiji, Kiribati, Mexico, Samoa, and Tonga. More specifically, it looks at the value-added components in an international teacher education program, with an emphasis on effective teaching and employability. Theoretically the study is based on Straus and Corbin’s (1998a) substantive grounded theory and Patton’s (1997) Theory of Action Framework. Verbal and non-verbal forms of feedback were identified as essential aspects of the international preservice training experience. Cultural diversity, teaching English as a second language, collaboration, and exposure to a different educational system were identified among several components as advantages to individuals who conduct their preservice teacher training in international settings.</jats:p

NONLINEAR ESTIMATION OF GROWTH CURVE MODELS FOR GERMINATION DATA ANALYSIS

Logistic, Gompertz, Richards and Weibull growth curves were evaluated for their suitability as mathematical and empirical models to represent cumulative germination. By avoiding the limitations associated with the method of moments and single-value germination indices, the fitted models provided superior description of the time course of germination. The four-parameter Weibull model gave the best fit across a relatively wide range of seed species and germination conditions, and the resulting parameter estimates reflected identifiable aspects of the germination process. The nonlinear estimation of the germination response included a parameter summary, together with their asymptotic standard errors and correlation matrix, along with an approximate band for the expectation function, pairwise plots of the parameter inference region, and profile t plots. Evaluation of the fitted models also included information on lack of fit and residual structure. Empirical results and hypothesis testing were demonstrated with reference to a replicated experiment designed to determine the effects of reduced water potential on germination of onion seeds

What we talk about when we talk about capacitance measured with the voltage-clamp step method

Capacitance is a fundamental neuronal property. One common way to measure capacitance is to deliver a small voltage-clamp step that is long enough for the clamp current to come to steady state, and then to divide the integrated transient charge by the voltage-clamp step size. In an isopotential neuron, this method is known to measure the total cell capacitance. However, in a cell that is not isopotential, this measures only a fraction of the total capacitance. This has generally been thought of as measuring the capacitance of the “well-clamped” part of the membrane, but the exact meaning of this has been unclear. Here, we show that the capacitance measured in this way is a weighted sum of the total capacitance, where the weight for a given small patch of membrane is determined by the voltage deflection at that patch, as a fraction of the voltage-clamp step size. This quantifies precisely what it means to measure the capacitance of the “well-clamped” part of the neuron. Furthermore, it reveals that the voltage-clamp step method measures a well-defined quantity, one that may be more useful than the total cell capacitance for normalizing conductances measured in voltage-clamp in nonisopotential cells

Seasonal variations in the diagnosis of childhood cancer in the United States

Seasonal trends in month of diagnosis have been reported for childhood acute lymphoblastic leukaemia (ALL) and non-Hodgkin's lymphoma (NHL). This seasonal variation has been suggested to represent an underlying viral aetiology for these malignancies. Some studies have shown the highest frequency of diagnoses in the summer months, although this has been inconsistent. Data from the Children's Cancer Group and the Pediatric Oncology Group were analysed for seasonal incidence patterns. A total of 20 949 incident cancer cases diagnosed in the USA from 1 January 1989 through 31 December 1991 were available for analyses. Diagnosis-specific malignancies available for evaluation included ALL, acute myeloid leukaemia (AML), Hodgkin's disease, NHL, rhabdomyosarcoma, neuroblastoma, retinoblastoma, osteosarcoma, Wilms' tumour, retinoblastoma, Ewings' sarcoma, central nervous system (CNS) tumours and hepatoblastoma. Overall, there was no statistically significant seasonal variation in the month of diagnosis for all childhood cancers combined. For diagnosis-specific malignancies, there was a statistically significant seasonal variation for ALL (P = 0.01; peak in summer), rhabdomyosarcoma (P = 0.03; spring/summer) and hepatoblastoma (P = 0.01; summer); there was no seasonal variation in the diagnosis of NHL. When cases were restricted to latitudes greater than 40° (‘north’), seasonal patterns were apparent only for ALL and hepatoblastoma. Notably, 33% of hepatoblastoma cases were diagnosed in the summer months. In contrast, for latitudes less than 40° (‘south’), only CNS tumours demonstrated a seasonal pattern (P = 0.002; winter). Although these data provide modest support for a summer peak in the diagnosis of childhood ALL, any underlying biological mechanisms that account for these seasonal patterns are likely complex and in need of more definitive studies. © 1999 Cancer Research Campaig

Short-term health-related quality of life consequences in a lung cancer CT screening trial (NELSON)

Item does not contain fulltextBACKGROUND: In lung cancer CT screening, participants often have an indeterminate screening result at baseline requiring a follow-up CT. In subjects with either an indeterminate or a negative result after screening, we investigated whether health-related quality of life (HRQoL) changed over time and differed between groups in the short term. METHODS: A total of 733 participants in the NELSON trial received four questionnaires: T0, before randomisation; T1, 1 week before the baseline screening; T2, 1 day after the screening; and T3, 2 months after the screening results but before the 3-month follow-up CT. HRQoL was measured as generic HRQoL (the 12-item Short Form, SF-12; the EuroQol questionnaire, EQ-5D), anxiety (the Spielberger State-Trait Anxiety Inventory, STAI-6), and lung-cancer-specific distress (the Impact of Event Scale, IES). For analyses, repeated-measures analysis of variance was used, adjusted for covariates. RESULTS: Response to each questionnaire was 88% or higher. Scores on SF-12, EQ-5D, and STAI-6 showed no clinically relevant changes over time. At T3, IES scores that were clinically relevant increased after an indeterminate result, whereas these scores showed a significant decrease after a negative result. At T3, differences in IES scores between the two baseline result groups were both significant and clinically relevant (P<0.01). CONCLUSION: This longitudinal study among participants of a lung cancer screening programme showed that in the short term recipients of an indeterminate result experienced increased lung-cancer-specific distress, whereas the HRQoL changes after a negative baseline screening result may be interpreted as a relief

Imaging Lung Disease in Systemic Sclerosis

Interstitial lung disease and pulmonary hypertension (PH) are the most common cardiopulmonary findings in patients with systemic sclerosis (SSc). About two thirds of patients suffering from SSc develop scleroderma interstitial lung disease. PH is present in about 20% of SSc patients and is typically associated with severe lung disease, although it may be an isolated manifestation of SSc. High-resolution CT scanning is a key method for evaluating chest involvement. There are four roles of imaging in scleroderma interstitial lung disease: 1) detection of lung involvement, 2) identification of patients likely to respond to treatment, 3) assessment of treatment efficacy, and 4) exclusion of other significant diseases to include PH and cardiac and esophageal abnormalities