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Year Regardless (year + regardless)
Selected AbstractsApparent inferiority of first-time breeders in the kittiwake: the role of heterogeneity among age classesJOURNAL OF ANIMAL ECOLOGY, Issue 3 2000Emmanuelle Cam Summary 1.,Many studies have provided evidence that first-time breeders have a lower survival, a lower probability of success, or of breeding, in the following year. Hypotheses based on reproductive costs have often been proposed to explain this. However, because of the intrinsic relationship between age and experience, the apparent inferiority of first-time breeders at the population level may result from selection, and experience may not influence performance within each individual. In this paper we address the question of phenotypic correlations between fitness components. This addresses differences in individual quality, a prerequisite for a selection process to occur. We also test the hypothesis of an influence of experience on these components while taking age and reproductive success into account: two factors likely to play a key role in a selection process. 2.,Using data from a long-term study on the kittiwake, we found that first-time breeders have a lower probability of success, a lower survival and a lower probability of breeding in the next year than experienced breeders. However, neither experienced nor inexperienced breeders have a lower survival or a lower probability of breeding in the following year than birds that skipped a breeding opportunity. This suggests heterogeneity in quality among individuals. 3.,Failed birds have a lower survival and a lower probability of breeding in the following year regardless of experience. This can be interpreted in the light of the selection hypothesis. The inferiority of inexperienced breeders may be linked to a higher proportion of lower-quality individuals in younger age classes. When age and breeding success are controlled for, there is no evidence of an influence of experience on survival or future breeding probability. 4.,Using data from individuals whose reproductive life lasted the same number of years, we investigated the influence of experience on reproductive performance within individuals. There is no strong evidence that a process operating within individuals explains the improvement in performance observed at the population level. [source] Opportunities for the stratospheric collection of dust from short-period cometsMETEORITICS & PLANETARY SCIENCE, Issue 11 2002Scott MESSENGER These comets have had the rare characteristics of low eccentricity, low inclination orbits with nodes very close to 1 AU. Dust from these comets is directly injected into Earth-crossing orbits by radiation pressure, unlike the great majority of interplanetary dust particles collected in the stratosphere which spend millennia in space prior to Earth-encounter. Complete dust streams from these comets form within a few decades, and appreciable amounts of dust are accreted by the Earth each year regardless of the positions of the parent comets. Dust from these comets could be collected in the stratosphere and identified by its short space exposure age, as indicated by low abundances of implanted solar-wind noble gases and/or lack of solar flare tracks. Dust from Grigg-Skjellerup probably has the highest concentration at Earth orbit. We estimate that the proportion of dust from this comet will reach at least several percent of the background interplanetary dust flux in the >40 ,m size range during April 23,24 of 2003. [source] Impact of storm-burning on Melaleuca viridiflora invasion of grasslands and grassy woodlands on Cape York Peninsula, AustraliaAUSTRAL ECOLOGY, Issue 2 2009GABRIEL CROWLEY Abstract This paper examines invasion of grasslands on Cape York Peninsula, Australia, by Melaleuca viridiflora and other woody species, and the role of storm-burning (lighting fires after the first wet season rains) in their maintenance. Trends in disturbance features, fuel characteristics, ground layer composition, and woody plants dynamics under combinations of withholding fire and storm-burning over a 3-year period were measured on 19 plots in three landscape settings. Population dynamics of M. viridiflora are described in detail and 20-year population projections based on transition matrices under different fire regimes generated. Numerous M. viridiflora suckers occurred within the grass layer, increasing each year regardless of fire regime, and were rapidly recruited to the canopy in the absence of fire. Storm-burning had little impact on fuel, ground layer or woody plant composition, but maintained open vegetation structure by substantially reducing recruitment of M. viridiflora suckers to the sapling layer, and by reducing the above-grass-layer abundance of several other invasive woody species. Population projections indicated that withholding fire for 20 years could cause a sevenfold increase of M. viridiflora density on Ti-tree flats, and that annual to triennial storm-burning should be effective at maintaining a stable open vegetation structure. These findings argue against vegetation thickening being an inevitable consequence of climate change. We conclude that a fire regime that includes regular storm-burning can be effective for maintaining grasslands and grassy woodlands being invaded by M. viridiflora. [source] Role of long-term lamivudine treatment of hepatitis B virus recurrence after liver transplantationJOURNAL OF MEDICAL VIROLOGY, Issue 11 2008Hyun Young Woo Abstract In this study, the long-term (>3 years) efficacy of combination therapy for hepatitis B virus (HBV) recurrence and the associated factors were investigated. One hundred and sixty-five consecutive HBsAg-positive patients (92 with liver cirrhosis, 73 with hepatocellular carcinoma; HCC) who underwent liver transplantation were assessed with a median follow-up time of 40 months. One hundred and twenty-one patients (121/165, 73.3%) were treated with lamivudine before transplantation for a mean of 8.4 months (range 0.1,72 months). The post-transplantation treatment protocol consisted of a high dose intravenous hepatitis B immunoglobulin (HBIg) followed by a low dose intramuscular HBIg and lamivudine combination therapy. Seven (4.2%, 7/165) recipients experienced HBV recurrence at a median time of 19 months (range 5,36 months) following transplantation. Six of seven cases of HBV recurrence were treated with lamivudine before transplantation for a median period of 15 months (range 0.6,30 months). Eighteen (24.6%, 18/73) patients had HCC recurrences after transplantation. Of the four patients with both HCC and HBV recurrence, three experienced HBV recurrence after recurrence of HCC. The clinical factor associated with HBV recurrence in the total cohort (n,=,165) was the duration of antiviral treatment (over 6 months) before transplantation (P,=,0.004). In the HCC group, HCC recurrence after transplantation (P,=,0.002), tumor burden before transplantation (P,=,0.005), and postoperative adjuvant chemotherapy (P,=,0.002), were additional factors for HBV recurrence. Combination therapy of HBIg and antiviral drugs was effective over 3 years regardless of the pretransplantation viral load. However, the possible recurrence of HBV needs to be monitored cautiously in patients treated with long-term (over 6 months) lamivudine. J. Med. Virol. 80:1891,1899, 2008. © 2008 Wiley-Liss, Inc. [source] Colorectal cancer in U.S. adults younger than 50 years of age, 1998,2001,CANCER, Issue S5 2006Temeika L. Fairley PhD Abstract BACKGROUND. Colorectal cancer (CRC) incidence rates are increasing among persons younger than 50 years of age, a population routinely not screened unless an individual has a high risk of CRC. This population-based study focuses primarily on describing the CRC burden for persons in this age group. METHODS. The data used for this study were derived from the National Program of Cancer Registries (NPCR) and Surveillance, Epidemiology, and End Results (SEER) surveillance systems. Age-adjusted incidence rates, rate ratios, and their corresponding 95% confidence intervals were calculated. RESULTS. CRC is ranked among the top 10 cancers occurring in males and females aged 20,49 years regardless of race. Persons younger than 50 years were more likely to present with less localized and more distant disease than do older adults. Among younger adults, age-adjusted incidence rates for poorly differentiated cancers were twice as high as rates for well-differentiated cancers. Incidence rates for poorly differentiated cancers were 60% higher than that for well-differentiated cancers diagnosed in older adults. Rates were significantly higher for blacks and significantly lower for Asians/Pacific Islanders when compared with that for whites for the most demographic and tumor characteristics examined. CONCLUSIONS. This study confirms the findings of previous population-based studies suggesting that younger patients present with more advanced disease than do older patients. This study also identifies racial and ethnic disparities in CRC incidence in this population. These findings suggest the need for additional studies to understand the behavior and etiology of CRC in blacks. Cancer 2006. © 2006 American Cancer Society. [source] | ||||||||||