3,981 research outputs found

    Analysis of monotonic greening and browning trends from global NDVI time-series

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    Remotely sensed vegetation indices are widely used to detect greening and browning trends; especially the global coverage of time-series normalized difference vegetation index (NDVI) data which are available from 1981. Seasonality and serial auto-correlation in the data have previously been dealt with by integrating the data to annual values; as an alternative to reducing the temporal resolution, we apply harmonic analyses and non-parametric trend tests to the GIMMS NDVI dataset (1981-2006). Using the complete dataset, greening and browning trends were analyzed using a linear model corrected for seasonality by subtracting the seasonal component, and a seasonal non-parametric model. In a third approach, phenological shift and variation in length of growing season were accounted for by analyzing the time-series using vegetation development stages rather than calendar days. Results differed substantially between the models, even though the input data were the same. Prominent regional greening trends identified by several other studies were confirmed but the models were inconsistent in areas with weak trends. The linear model using data corrected for seasonality showed similar trend slopes to those described in previous work using linear models on yearly mean values. The non-parametric models demonstrated the significant influence of variations in phenology; accounting for these variations should yield more robust trend analyses and better understanding of vegetation trends

    Chytrid epidemics may increase genetic diversity of a diatom spring-bloom

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    Contrary to expectation, populations of clonal organisms are often genetically highly diverse. In phytoplankton, this diversity is maintained throughout periods of high population growth (that is, blooms), even though competitive exclusion among genotypes should hypothetically lead to the dominance of a few superior genotypes. Genotype-specific parasitism may be one mechanism that helps maintain such high-genotypic diversity of clonal organisms. Here, we present a comparison of population genetic similarity by estimating the beta-dispersion among genotypes of early and peak bloom populations of the diatom Asterionella formosa for three spring-blooms under high or low parasite pressure. The Asterionella population showed greater beta-dispersion at peak bloom than early bloom in the 2 years with high parasite pressure, whereas the within group dispersion did not change under low parasite pressure. Our findings support that high prevalence parasitism can promote genetic diversification of natural populations of clonal hosts

    The collaborative dynamic in social entrepreneurship

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    © 2017 Informa UK Limited, trading as Taylor & Francis Group. Collaborative arrangements and partnerships are increasingly perceived as the lifeblood of social entrepreneurship. How, why and when collaboration occurs across the social entrepreneurial ecosystem is an emergent area of research emphasis with potential to contribute to and develop new theories as well as provide practical insights. This introductory article, for the special issue on ‘The Collaborative Dynamic in Social Entrepreneurship’, draws on extant literature and three original contributions to explore the nature and challenges of the collaborative imperative in social entrepreneurship and to present possible avenues for future research. It also comments on theoretical underpinnings and provides methodological insights for the future study of collaborative social entrepreneurship

    The collaborative dynamic in social entrepreneurship

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    © 2017 Informa UK Limited, trading as Taylor & Francis Group. Collaborative arrangements and partnerships are increasingly perceived as the lifeblood of social entrepreneurship. How, why and when collaboration occurs across the social entrepreneurial ecosystem is an emergent area of research emphasis with potential to contribute to and develop new theories as well as provide practical insights. This introductory article, for the special issue on ‘The Collaborative Dynamic in Social Entrepreneurship’, draws on extant literature and three original contributions to explore the nature and challenges of the collaborative imperative in social entrepreneurship and to present possible avenues for future research. It also comments on theoretical underpinnings and provides methodological insights for the future study of collaborative social entrepreneurship

    Informing, simulating experience, or both: A field experiment on phishing risks

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    Cybersecurity cannot be ensured with mere technical solutions. Hackers often use fraudulent emails to simply ask people for their password to breach into organizations. This technique, called phishing, is a major threat for many organizations. A typical prevention measure is to inform employees but is there a better way to reduce phishing risks? Experience and feedback have often been claimed to be effective in helping people make better decisions. In a large field experiment involving more than 10,000 employees of a Dutch ministry, we tested the effect of information provision, simulated experience, and their combination to reduce the risks of falling into a phishing attack. Both approaches substantially reduced the proportion of employees giving away their password. Combining both interventions did not have a larger impact

    The gait and balance of patients with diabetes can be improved: a randomised controlled trial

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    Aims/hypothesis: Gait characteristics and balance are altered in diabetic patients. Little is known about possible treatment strategies. This study evaluates the effect of a specific training programme on gait and balance of diabetic patients. Methods: This was a randomised controlled trial (n = 71) with an intervention (n = 35) and control group (n = 36). The intervention consisted of physiotherapeutic group training including gait and balance exercises with function-orientated strengthening (twice weekly over 12weeks). Controls received no treatment. Individuals were allocated to the groups in a central office. Gait, balance, fear of falls, muscle strength and joint mobility were measured at baseline, after intervention and at 6-month follow-up. Results: The trial is closed to recruitment and follow-up. After training, the intervention group increased habitual walking speed by 0.149m/s (p < 0.001) compared with the control group. Patients in the intervention group also significantly improved their balance (time to walk over a beam, balance index recorded on Biodex balance system), their performance-oriented mobility, their degree of concern about falling, their hip and ankle plantar flexor strength, and their hip flexion mobility compared with the control group. After 6months, all these variables remained significant except for the Biodex sway index and ankle plantar flexor strength. Two patients developed pain in their Achilles tendon: the progression for two related exercises was slowed down. Conclusions/interpretation: Specific training can improve gait speed, balance, muscle strength and joint mobility in diabetic patients. Further studies are needed to explore the influence of these improvements on the number of reported falls, patients' physical activity levels and quality of life. Trial registration:: ClinicalTrials.gov NCT00637546 Funding:: This work was supported by the Swiss National Foundation (SNF): PBSKP-123446/

    PROMISE:effect of protein supplementation on fat-free mass preservation after bariatric surgery, a randomized double-blind placebo-controlled trial

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    Introduction: Protein malnutrition after bariatric surgery is a severe complication and leads to significant morbidity. Previous studies have shown that protein intake and physical activity are the most important factors in the preservation of fat-free mass during weight loss. Low protein intake is very common in patients undergoing bariatric surgery despite dietary counseling. Protein powder supplements might help patients to achieve the protein intake recommendations after bariatric surgery and could therefore contribute to preserve fat-free mass. This double-blind randomized placebo-controlled intervention study aims to assess the effect of a daily consumed clear protein powder shake during the first 6 months after bariatric surgery on fat-free mass loss in the first 12 months after laparoscopic Roux-en-Y gastric bypass (LRYGB). Methods and analysis:Inclusion will take place at the outpatient clinic of the bariatric expertise center for obesity of the Maasstad Hospital. Patients will be randomly assigned to either the intervention or control group before surgery. The intervention group will receive a clear protein powder shake of 200 ml containing 20 g of whey protein dissolved in water which should be taken daily during the first 6 months after LRYGB on top of their normal postoperative diet. The control group will receive an isocaloric, clear, placebo shake containing maltodextrine. Postoperative rehabilitation and physiotherapeutical guidance will be standardized and similar in both groups. Also, both groups will receive the same dietary advice from specialized dieticians. The main study parameter is the percentage of fat-free mass loss 6 months after surgery, assessed by multi-frequency bioelectrical impedance analysis (MF-BIA). Ethics and dissemination: The protocol, version 2 (February 20, 2022) has been approved by the Medical Research Ethics Committees United (MEC-U) (NL 80414.100.22). The results of this study will be submitted to peer-reviewed journals. Trial registration: ClinicalTrials.gov NCT05570474. Registered on October 5, 2022.</p

    Individual human serum differs in the amount of antibodies with affinity for pig fetal ventral mesencephalic cells and the ability to lyse these cells by complement activation

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    Xenografting pig fetal ventral mesencephalic (pfVM) cells to repair the dopamine deficit in patients with Parkinson's disease is the focus of both experimental and clinical investigations. Although there have been marked advances in the experimental and even clinical application of these xenogeneic transplantations, questions regarding the host's xenospecific immune response remain unanswered. It has been shown that human serum is able to lyse pfVM tissue by both anti-gal-gal and non-anti-gal-gal antibodies by complement activation. The aim of this study was to investigate whether interindividual differences exist in the levels of pfVM cell-specific IgM and IgG subclass antibodies, their ability to lyse pfVM cells in vitro and the relationship between both. Pig fetal VM cells were incubated with heat-inactivated serum from 10 different individuals and binding of IgM antibodies and IgG subclass antibodies to pfVM cells was analyzed by flow cytometry. The ability to lyse pfVM cells was analyzed exposing Cr-51-labeled pfVM cells to fresh serum or isolated IgM and IgG from the same individuals and subsequent determination of released Cr-51 from lysed cells. Strong differences were found between individuals in the levels of pfVM cell-specific IgM antibodies: antibody levels differed up to 40-fold. pfVM-specific IgG1 and IgG2 levels were only detectable in a few individuals. The ability to lyse pfVM cells ranged from negligible lysis up to 66.5% specific lysis. There was a strong correlation between the levels of individual pfVM-specific IgM antibodies and the ability to lyse pfVM cells in vitro. Isolated IgM, but not IgG, was able to lyse pfVM cells in the presence of complement. In conclusion, the interindividual differences in the levels of IgM with affinity for pfVM cells and their ability to lyse pfVM cells in vitro are considerable. Only few individuals possessed IgG1 and IgG2 subclass antibodies with affinity for pfVM. These findings may influence patient selection for porcine transplants and chances of graft survival in individual patients

    Effect of dupilumab on hand eczema in patients with atopic dermatitis:An observational study

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    Systemic treatment options for chronic hand eczema are limited. Dupilumab is used in atopic dermatitis (AD) but is not licensed for (isolated) hand eczema. In this observational prospective study we aimed to determine the response of hand eczema to dupilumab in patients with AD. Adult patients with hand eczema and AD received dupilumab s.c. at a 600 mg loading dose, followed by 300 mg every 2 weeks. Primary outcome was a minimum improvement of 75% on the Hand Eczema Severity Index after 16 weeks (HECSI-75). Secondary outcomes were severity, measured using the Photographic guide; quality of life improvement as patient-reported outcome, measured using the Dermatology Life Quality Index (DLQI); and AD severity, measured using the Eczema Area and Severity Index (EASI). Forty-seven patients were included (32 males; mean age, 45 years). HECSI-75 was achieved by 28 (60%). Mean HECSI score reduction was 49.2 points (range, 0-164; 95% within-subject confidence interval, 46.4-52.0), which was already significantly decreased after 4 weeks (P < 0.001). DLQI score mean improvement was 8.8 points (standard deviation [SD], 6.0) or 70.0% decrease (SD, 26.4) (P < 0.001). Eighteen patients (38%) were classified as responders on the Photographic guide. There was no difference in response between chronic fissured and recurrent vesicular clinical subtypes. Similar percentages of patients achieving EASI-75 and HECSI-75 were seen after 16 weeks. In conclusion, this study shows a favorable response of hand eczema to dupilumab in patients with AD. This raises the question whether a response will also be seen in isolated hand eczema
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