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Cycle Characteristics (cycle + characteristic)
Selected AbstractsFINE SCALE VARIABILITY IN SOIL FROST DYNAMICS SURROUNDING CUSHIONS OF THE DOMINANT VASCULAR PLANT SPECIES (AZORELLA SELAGO) ON SUB-ANTARCTIC MARION ISLANDGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 4 2009NATALIE S. HAUSSMANN ABSTRACT. Through changing soil thermal regimes, soil moisture and affecting weathering and erosion processes plants can have an important effect on the physical properties and structure of soils. Such physical soil changes can in turn lead to biological facilitation, such as vegetation-banked terrace formation or differential seedling establishment. We studied the fine scale variability in soil temperature and moisture parameters, specifically focusing on frost cycle characteristics around cushions of the dominant, vascular plant species, Azorella selago, on sub-Antarctic Marion Island. The frost season was characterised by numerous low intensity and very shallow frost cycles. Soils on eastern cushion sides were found to have lower mean and maximum temperatures in winterthan soils on western cushion sides. In addition, lower variability in temperature was found on eastern cushion sides in winterthan on western cushion sides, probably as a result of higher wind speeds on western cushion sides and/or eastern, lee-side snow accumulation. Despite the mild frost climate, extensive frost heave occurred in the study area, indicating that needle ice forms at temperatures above ,2°C. Our results demonstrate the effectiveness of frost pull as a heave mechanism under shallow frost conditions. The results highlight the importance of Azorella cushions in modifying site microclimates and of understanding the consequences of these modifications, such as potentially providing microhabitats. Such potential microhabitats are particularly important in light of current climate change trends on the island, as continued warming and drying will undoubtedly increase the need for thermal and moisture refugia. [source] Analysis of an unconventional cycle as a new comparison standard for practical heat engines: the circular/elliptical cycle in T,S diagramINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2004Bahri Sahin Abstract An unconventional cycle analysis in the T,S diagram has been carried out and the cycle characteristics such as thermal efficiency, work density (defined as the ratio of the network output to the maximum volume in the cycle), maximum volume and maximum pressure are determined. The obtained results for the unconventional cycle are compared with those of the Carnot cycle. It is proposed that the analysed unconventional cycle may be used as a better comparison standard than the Carnot cycle for practical heat engines when both size and thermal efficiency are considered. Copyright © 2004 John Wiley & Sons, Ltd. [source] Proliferative and apoptotic differences between alveolar rhabdomyosarcoma subtypes: A comparative study of tumors containing PAX3-FKHR or PAX7-FKHR gene fusionsPEDIATRIC BLOOD & CANCER, Issue 2 2001Margaret H. Collins MD Abstract Background Most alveolar rhabdomyosarcomas (ARMS) have chromosome translocations and resultant gene fusion products. The more common translocation fuses the PAX3 and FKHR genes; patients who have PAX3-FKHR-positive ARMS have reduced event-free survival compared to patients with ARMS containing the less common translocation that fuses the PAX7 and FKHR genes. Procedure We examined histology, immunohistochemical markers of differentiation, and cell cycle characteristics of a panel of ARMS containing either PAX3-FKHR or PAX7-FKHR transcript to determine if these features differ between the ARMS subsets. Results Cell cycle parameters varied significantly: the number of nuclei that stained with either an immunohistochemical marker of proliferation (MIB1), or a TUNEL-based assay for apoptosis was significantly greater in tumors that expressed PAX3-FKHR compared to tumors that expressed PAX7-FKHR transcript. Conclusions We conclude that compared to PAX7-FKHR-containing tumors, ARMS that contain PAX3-FKHR transcript have (1) increased cell proliferation, consistent with greater loss of cell cycle regulation, and (2) apoptosis that is increased but insufficient to prevent tumor formation. More marked cell cycle dysregulation may contribute to poorer prognosis for patients with ARMS that have PAX3-FKHR fusion. Med Pediatr Oncol 2001;37:83,89. © 2001 Wiley-Liss, Inc. [source] Menstrual cycle variability and the perimenopauseAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2001Kathleen A. O'Connor Menopause, the final cessation of menstrual cycling, occurs when the pool of ovarian follicles is depleted. The one to five years just prior to the menopause are usually marked by increasing variability in menstrual cycle length, frequency of ovulation, and levels of reproductive hormones. Little is known about the mechanisms that account for these characteristics of ovarian cycles as the menopause approaches. Some evidence suggests that the dwindling pool of follicles itself is responsible for cycle characteristics during the perimenopausal transition. Another hypothesis is that the increased variability reflects "slippage" of the hypothalamus, which loses the ability to regulate menstrual cycles at older reproductive ages. This paper examines the underlying cause of the increasing variability in menstrual cycle length prior to the menopause. A model of ovarian cycles is developed, based on the process of follicular growth and depletion. Under this model, the follicular phase of each menstrual cycle is preceded by an inactive phase, a period of time when no ovarian follicles have left the resting state and begun secreting steroids in response to gonadotropin stimulation. The model makes predictions about the variability in menstrual cycles across the reproductive life span based on the size of the surviving pool of ovarian follicles. We show that the model can explain several characteristics of the perimenopause in humans and macaques and illustrate how the model can be applied to research on the biological and cultural correlates of the timing of menopause. J. Hum. Biol. 13:465,478, 2001. © 2001 Wiley-Liss, Inc. [source] Photosynthesis and Photoprotection in Overwintering PlantsPLANT BIOLOGY, Issue 5 2002W. W. Adams III Abstract: Seasonal differences in the capacity of photosynthetic electron transport, leaf pigment composition, xanthophyll cycle characteristics and chlorophyll fluorescence emission were investigated in two biennial mesophytes (Malva neglecta and Verbascum thapsus) that grow in full sunlight, and in leaves/needles of sun and shade populations of several broad-leafed evergreens and conifers (Vinca minor, Euonymus kiautschovicus, Mahonia repens, Pseudotsuga menziesii [Douglas fir], and Pinus ponderosa). Both mesophytic species maintained or upregulated photosynthetic capacity in the winter and exhibited no upregulation of photoprotection. In contrast, photosynthetic capacity was downregulated in sun leaves/needles of V. minor, Douglas fir, and Ponderosa pine, and even in shade needles of Douglas fir. Interestingly, photosynthetic capacity was upregulated during the winter in shade leaves/needles of V. minor, Ponderosa pine and Euonymus kiautschovicus. Nocturnal retention of zeaxanthin and antheraxanthin, and their sustained engagement in a state primed for energy dissipation, were observed largely in the leaves/needles of sun-exposed evergreen species during winter. Factors that may contribute to these differing responses to winter stress, including chloroplast redox state, the relative levels of source and sink activity at the whole plant level, and apoplastic versus symplastic phloem loading, are discussed. [source] Relationship between group sunspot numbers and Wolf sunspot numbersASTRONOMISCHE NACHRICHTEN, Issue 7 2010K.J. Li Abstract Continuous wavelet transform and cross-wavelet transform have been used to investigate the phase periodicity and synchrony of the monthly mean Wolf (Rz) and group (Rg) sunspot numbers during the period of June 1795 to December 1995. The Schwabe cycle is the only one common period in Rg and Rz, but it is not well-defined in case of cycles 5,7 of Rg and in case of cycles 5 and 6 of Rz. In fact, the Schwabe period is slightly different in Rg and Rz before cycle 12, but from cycle 12 onwards it is almost the same for the two time series. Asynchrony of the two time series is more obviously seen in cycles 5 and 6 than in the following cycles, and usually more obviously seen around the maximum time of a cycle than during the rest of the cycle. Rg is found to fit Rz better in both amplitudes and peak epoch during the minimum time time of a solar cycle than during the maximum time of the cycle, which should be caused by their different definition, and around the maximum time of a cycle, Rg is usually less than Rz. Asynchrony of Rg and Rz should somewhat agree with different sunspot cycle characteristics exhibited by themselves (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Efficacy of micronised vaginal progesterone versus oral dydrogestrone in the treatment of irregular dysfunctional uterine bleeding: A pilot randomised controlled trialAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 6 2009Savas KARAKUS Background:, The vaginal route is more effective than the other drug delivery routes for some specific indications. Aim:, To compare the efficacy of a vaginal progesterone preparation with that of oral dydrogesterone. Methods:, A total of 69 women with irregular dysfunctional uterine bleeding were randomly assigned into one of two groups: oral dydrogesterone group (n = 35) and vaginal progesterone group (n = 34). At the end of a three-month treatment period, the women were re-evaluated. The endometrial histology findings and menstrual cycle characteristics were used as primary outcome measures. Pearson chi-square and Fisher's exact test were used for data analysis. Results:, Findings from 54 eligible women were evaluated. There was no statistically significant difference in both menstrual recordings and endometrial histology results between the groups. Conclusions:, Vaginal micronised progesterone could be an alternative to oral preparations in the treatment of dysfunctional uterine bleeding. This needs to be further evaluated in adequately controlled randomised trials against other effective treatments. [source] Risk factors on the menstrual cycle of healthy Taiwanese college nursing studentsAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 6 2009Pei-Jen CHANG Background:, The purpose of this study was to explore risk factors, including age at menarche, body mass index (BMI), psychiatric stress and physical exercise on the menstrual cycle of healthy Taiwanese college nursing students. Methods:, We conducted a cross-sectional survey involving 1300 female college students in the nursing curriculum between December 2002 and March 2003. We provided a structured questionnaire for each student. Information on the women's demographics, lifestyles and reproductive history related to menstrual cycle characteristics was requested. A total of 1095 healthy students were included in the analysis. A logistic regression was used to estimate the odds ratios for each of the menstrual cycle characteristics. Results:, We found that age at menarche, BMI and psychiatric stress were associated with menstrual cycle characteristics in healthy college nursing students. In addition to menarche at the age of 14 years or later, obesity and psychological stress, menarche before 12 years of age was an important risk factor for menstrual dysfunction. Moreover, obese students had the highest risk of having a longer cycle and cycle irregularity. Conclusions:, Early menarche might be related to menstrual dysfunction in addition to late menarche, obesity and psychological stress. Moreover, obese students are at the highest risks for longer cycles and cycle irregularity. [source] Microtubule-dependent organization of subcortical microfilaments in the early Drosophila embryoDEVELOPMENTAL DYNAMICS, Issue 3 2007Maria Giovanna Riparbelli Abstract Dynamic alterations in the spatial organization of cytoskeletal elements constitute a prominent morphological feature of the early, syncytial stages of embryogenesis in Drosophila. Here, we describe and characterize the dynamic behavior of cytoplasmic, subcortical microfilaments, which form a series of nucleus-associated structures, at different phases of the simultaneous nuclear division cycles characteristic of early Drosophila embryos. Remodeling of the cytoplasmic microfilament arrays takes place in parallel to the established cyclic reorganization of cortical microfilament structures. We provide evidence that the cortical and subcortical microfilament populations organize independently of each other, and in response to distinct instructive cues. Specifically, formation of subcortical microfilament structures appears to rely on, and spatially mirror, the organization of polarized microtubule arrays, while cortical microfilament restructuring constitutes a centrosome-dependent process. Genetic analysis identifies a requirement for SCAR, a key mediator of Arp2/3-based microfilament dynamics, in organization of subcortical microfilament structures. Developmental Dynamics 236:662,670, 2007. © 2007 Wiley-Liss, Inc. [source] | |||||||||||||