2,519 research outputs found

    Pteropods are excellent recorders of surface temperature and carbonate ion concentration

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    Pteropods are among the first responders to ocean acidification and warming, but have not yet been widely explored as carriers of marine paleoenvironmental signals. In order to characterize the stable isotopic composition of aragonitic pteropod shells and their variation in response to climate change parameters, such as seawater temperature, pteropod shells (Heliconoides inflatus) were collected along a latitudinal transect in the Atlantic Ocean (31° N to 38° S). Comparison of shell oxygen isotopic composition to depth changes in the calculated aragonite equilibrium oxygen isotope values implies shallow calcification depths for H. inflatus (75 m). This species is therefore a good potential proxy carrier for past variations in surface ocean properties. Furthermore, we identified pteropod shells to be excellent recorders of climate change, as carbonate ion concentration and temperature in the upper water column have dominant influences on pteropod shell carbon and oxygen isotopic composition. These results, in combination with a broad distribution and high abundance, make the pteropod species studied here, H. inflatus, a promising new proxy carrier in paleoceanography

    Selection of Reserves for Woodland Caribou Using an Optimization Approach

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    Habitat protection has been identified as an important strategy for the conservation of woodland caribou (Rangifer tarandus). However, because of the economic opportunity costs associated with protection it is unlikely that all caribou ranges can be protected in their entirety. We used an optimization approach to identify reserve designs for caribou in Alberta, Canada, across a range of potential protection targets. Our designs minimized costs as well as three demographic risk factors: current industrial footprint, presence of white-tailed deer (Odocoileus virginianus), and climate change. We found that, using optimization, 60% of current caribou range can be protected (including 17% in existing parks) while maintaining access to over 98% of the value of resources on public lands. The trade-off between minimizing cost and minimizing demographic risk factors was minimal because the spatial distributions of cost and risk were similar. The prospects for protection are much reduced if protection is directed towards the herds that are most at risk of near-term extirpation

    Fractional Cauchy problems on bounded domains: survey of recent results

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    In a fractional Cauchy problem, the usual first order time derivative is replaced by a fractional derivative. This problem was first considered by \citet{nigmatullin}, and \citet{zaslavsky} in Rd\mathbb R^d for modeling some physical phenomena. The fractional derivative models time delays in a diffusion process. We will give a survey of the recent results on the fractional Cauchy problem and its generalizations on bounded domains D\subset \rd obtained in \citet{m-n-v-aop, mnv-2}. We also study the solutions of fractional Cauchy problem where the first time derivative is replaced with an infinite sum of fractional derivatives. We point out a connection to eigenvalue problems for the fractional time operators considered. The solutions to the eigenvalue problems are expressed by Mittag-Leffler functions and its generalized versions. The stochastic solution of the eigenvalue problems for the fractional derivatives are given by inverse subordinators

    Quality of life, functional outcome, and voice handicap index in partial laryngectomy patients for early glottic cancer

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    BACKGROUND: In this study, we aim to gather information about the quality of life issues, functional outcomes and voice problems facing early glottic cancer patients treated with the surgical techniques such as laryngofissure cordectomy, fronto-lateral laryngectomy, or cricohyoidopexi. In particular, consistency of life and voice quality issues with the laryngeal tissue excised during surgery is examined. In addition, the effects of arytenoidectomy to the life and voice quality are also studied. METHODS: 29 male patients were enrolled voluntarily in the study. The average age was 53.9 years. Three out of 10 patients with laryngofissure cordectomy also had arytenoidectomy. 11 patients had fronto-lateral laryngectomy with Tucker reconstruction, two of which also had arytenoidectomy. There were eight patients with cricohyoidopexi and bilateral functional neck dissection. Three of these patients also had arytenoidectomy. In bilateral functional neck dissection cases, spinal accessory nerve was preserved and level V of the neck was not dissected. None of the patients had neither radiotherapy nor voice therapy. Cordectomy patients never had a temporary tracheotomy or were connected to a feeding tube. Data was collected for 13 months for the cordectomy group, 14 months for fronto-lateral laryngectomy and cricohyoidopexi groups on average post-operatively. Statistical analysis in this study was carried out using the one-way analysis of variance, and the Post-Hoc group comparisons were made after Bonferroni and Scheffé-procedures. In order to determine the effects of arytenoidectomy, a regression analysis is carried out to see if there are statistical differences in answers given to the survey questions among patients who were arytenoidectomized during their surgeries. RESULTS: There was a statistically significant difference between cordectomy and cricohyoidopexi group in answers to the University of Washington- Quality of Life- Revised survey part 1. (p = 0). A statistically significant difference was also established between cordectomy and fronto-lateral laryngectomy groups, as well as between cordectomy and cricohyoidopexi groups in answers to the University of Washington- Quality of Life- Revised survey part 2. (p = 0,036 and p = 0.009, respectively). Cricohyoidopexi group has given the lowest scores and the cordectomy group has given the highest scores in three survey questions representing the quality of life, performances and new voices. These ranges are also consistent with the laryngeal tissue excised during surgery (cricohyoidopexi > fronto-lateral laryngectomy > cordectomy). There was no statistically significant difference between groups in Performance Status Scale for Head and Neck cancer patients instrument. The difference between the Voice Handicap Index and Voice Handicap Index (functional); Voice Handicap Index (physical) and Voice Handicap Index (emotional) scores in three patient groups was not significant either. All of the patients evaluated that their new voices have similar functional, physical and emotional impact on their life. Decanulation and oral feeding times of cricohyoidopexi and fronto-lateral laryngectomy patients are found to be significantly longer than cordectomy patients. Lastly, the removal of arytenoid does not have any significant adverse effects on the quality of life, the functional outcomes, or the quality of voice. CONCLUSION: In the present study, all patients with early glottic cancer, treated with different surgical technics reported fairly good quality of life outcomes, functional results and voice qualities. This study also finds that the removal of arytenoid does not have any adverse effects on the quality of life and voice from the patients' point of view

    How Preussag became TUI : kissing too many toads can make you a toad

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    In the period 1997-2004, Preussag, a diversified German conglomerate of old economy businesses, changed itself into TUI, a company focused almost entirely on tourism and logistics. This paper analyzes how this strategy was executed and how it contributed to Preussag’s underperformance of the stock market. We collect 417 announcements of acquisitions, financial disclosures and other news and disentangle the impact of different parts of the company’s strategy. We find that only the divestitures created value, that the strategy to invest in tourism destroyed value, and that the acquisition premiums Preussag paid were mostly unjustified. Bad luck like the events of September 11, 2001 cannot account for the poor performance of the stock. Poor management resulted from poor governance, combining a state-owned bank as the largest shareholder, board interlocks, and insufficient managerial incentives. The case shows how divestiture programs increase the liquid resources available to management beyond free operating cash flows and casts doubt on the positive governance role of institutional blockholders

    Transactivation of EGFR by LPS induces COX-2 expression in enterocytes

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    Necrotizing enterocolitis (NEC) is the leading cause of gastrointestinal morbidity and mortality in preterm infants. NEC is characterized by an exaggerated inflammatory response to bacterial flora leading to bowel necrosis. Bacterial lipopolysaccharide (LPS) mediates inflammation through TLR4 activation and is a key molecule in the pathogenesis of NEC. However, LPS also induces cyclooxygenase-2 (COX-2), which promotes intestinal barrier restitution through stimulation of intestinal cell survival, proliferation, and migration. Epidermal growth factor receptor (EGFR) activation prevents experimental NEC and may play a critical role in LPS-stimulated COX-2 production. We hypothesized that EGFR is required for LPS induction of COX-2 expression. Our data show that inhibiting EGFR kinase activity blocks LPS-induced COX-2 expression in small intestinal epithelial cells. LPS induction of COX-2 requires Src-family kinase signaling while LPS transactivation of EGFR requires matrix metalloprotease (MMP) activity. EGFR tyrosine kinase inhibitors block LPS stimulation of mitogen-activated protein kinase ERK, suggesting an important role of the MAPK/ERK pathway in EGFR-mediated COX-2 expression. LPS stimulates proliferation of IEC-6 cells, but this stimulation is inhibited with either the EGFR kinase inhibitor AG1478, or the selective COX-2 inhibitor Celecoxib. Taken together, these data show that EGFR plays an important role in LPS-induction of COX-2 expression in enterocytes, which may be one mechanism for EGF in inhibition of NEC

    Novel application and validation of in vivo micro‐CT to study bone modelling in 3D

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149362/1/ocr12265.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149362/2/ocr12265_am.pd

    Tea and coffee consumption in relation to vitamin D and calcium levels in Saudi adolescents

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    Background Coffee and tea consumption was hypothesized to interact with variants of vitamin D-receptor polymorphisms, but limited evidence exists. Here we determine for the first time whether increased coffee and tea consumption affects circulating levels of 25-hydroxyvitamin D in a cohort of Saudi adolescents. Methods A total of 330 randomly selected Saudi adolescents were included. Anthropometrics were recorded and fasting blood samples were analyzed for routine analysis of fasting glucose, lipid levels, calcium, albumin and phosphorous. Frequency of coffee and tea intake was noted. 25-hydroxyvitamin D levels were measured using enzyme-linked immunosorbent assays. Results Improved lipid profiles were observed in both boys and girls, as demonstrated by increased levels of HDL-cholesterol, even after controlling for age and BMI, among those consuming 9–12 cups of coffee/week. Vitamin D levels were significantly highest among those consuming 9–12 cups of tea/week in all subjects (p-value 0.009) independent of age, gender, BMI, physical activity and sun exposure. Conclusion This study suggests a link between tea consumption and vitamin D levels in a cohort of Saudi adolescents, independent of age, BMI, gender, physical activity and sun exposure. These findings should be confirmed prospectively
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