Islands of change vs. islands of disaster: Managing pigs and birds in the Anthropocene of the North Atlantic

The offshore islands of the North Atlantic were among some of the last settled places on earth, with humans reaching the Faroes and Iceland in the late Iron Age and Viking period. While older accounts emphasizing deforestation and soil erosion have presented this story of island colonization as yet another social–ecological disaster, recent archaeological and paleoenvironmental research combined with environmental history, environmental humanities, and bioscience is providing a more complex understanding of long-term human ecodynamics in these northern islands. An ongoing interdisciplinary investigation of the management of domestic pigs and wild bird populations in Faroes and Iceland is presented as an example of sustained resource management using local and traditional knowledge to create structures for successful wild fowl management on the millennial scale

Large-scale unit commitment under uncertainty: an updated literature survey

The Unit Commitment problem in energy management aims at finding the optimal production schedule of a set of generation units, while meeting various system-wide constraints. It has always been a large-scale, non-convex, difficult problem, especially in view of the fact that, due to operational requirements, it has to be solved in an unreasonably small time for its size. Recently, growing renewable energy shares have strongly increased the level of uncertainty in the system, making the (ideal) Unit Commitment model a large-scale, non-convex and uncertain (stochastic, robust, chance-constrained) program. We provide a survey of the literature on methods for the Uncertain Unit Commitment problem, in all its variants. We start with a review of the main contributions on solution methods for the deterministic versions of the problem, focussing on those based on mathematical programming techniques that are more relevant for the uncertain versions of the problem. We then present and categorize the approaches to the latter, while providing entry points to the relevant literature on optimization under uncertainty. This is an updated version of the paper "Large-scale Unit Commitment under uncertainty: a literature survey" that appeared in 4OR 13(2), 115--171 (2015); this version has over 170 more citations, most of which appeared in the last three years, proving how fast the literature on uncertain Unit Commitment evolves, and therefore the interest in this subject

Representing spatial variability of snow water equivalent in hydrologic and land-surface models: a review

This paper evaluates the use of field data on the spatial variability of snow water equivalent (SWE) to guide the design of distributed snow models. An extensive reanalysis of results from previous field studies in different snow environments around the world is presented, followed by an analysis of field data on spatial variability of snow collected in the headwaters of the Jollie River basin, a rugged mountain catchment in the Southern Alps of New Zealand. In addition, area-averaged simulations of SWE based on different types of spatial discretization are evaluated. Spatial variability of SWE is shaped by a range of different processes that occur across a hierarchy of spatial scales. Spatial variability at the watershed-scale is shaped by variability in near-surface meteorological fields (e.g., elevation gradients in temperature) and, provided suitable meteorological data is available, can be explicitly resolved by spatial interpolation/extrapolation. On the other hand, spatial variability of SWE at the hillslope-scale is governed by processes such as drifting, sloughing of snow off steep slopes, trapping of snow by shrubs, and the nonuniform unloading of snow by the forest canopy, which are more difficult to resolve explicitly. Subgrid probability distributions are often capable of representing the aggregate-impact of unresolved processes at the hillslope-scale, though they may not adequately capture the effects of elevation gradients. While the best modeling strategy is case-specific, the analysis in this paper provides guidance on both the suitability of several common snow modeling approaches and on the choice of parameter values in subgrid probability distributions.Martyn P. Clark, Jordy Hendrikx, Andrew G. Slater, Dmitri Kavetski, Brian Anderson, Nicolas J. Cullen, Tim Kerr, Einar Örn Hreinsson and Ross A. Wood

Bleeding-related symptoms in colorectal cancer: a 4-year nationwide population-based study.

To access publisher's full text version of this article click on the hyperlink at the bottom of the pageLittle is known about the major presenting features of patients with colorectal cancer (CRC) in a population-based setting, especially regarding bleeding-related symptoms.To determine the proportion of CRC patients presenting with bleeding-related symptoms, to compare bleeders and nonbleeders and to explore the role of anticoagulants in bleeders.This was a nationwide, population-based, retrospective study, investigating all patients diagnosed with CRC in Iceland from 2008 to 2011. Bleeding-related symptoms were defined as overt bleeding, iron deficiency anaemia or a positive faecal occult blood test. Obstructive symptoms were defined as a confirmed diagnosis of ileus or dilated intestines on imaging.Data were available for 472/496 (95%) patients, males 51%, mean age 69 (±13) years. In all, 348 (74%) patients had bleeding-related symptoms; of these 348 patients, 61% had overt bleeding. Bleeders were less likely than nonbleeders to have metastases at diagnosis, 19% vs. 34% (P < 0.001). Overt bleeders were less likely than nonbleeders to have obstructive symptoms, 2% vs. 16% respectively (P < 0.0001). Occult bleeders were more likely to have proximal cancer (69%) than both overt (17%) and nonbleeders (44%) (P < 0.0001); however, they were less likely than nonbleeders to have metastases (22% vs. 35%, P < 0.05). Bleeders were more likely to use warfarin than nonbleeders (9% vs. 3%, P < 0.05); the use of low-dose aspirin was the same (24%).The majority of patients with CRC present with bleeding-related symptoms. Bleeders with CRC present earlier than nonbleeders. Warfarin use may induce bleeding in some patients, resulting in an earlier diagnosis.Landspitali National University Hospital of Iceland Research Fund

Incidence of diverticular bleeding: a population-based study.

To access publisher's full text version of this article click on the hyperlink belowOBJECTIVE: To determine the incidence of diverticular bleeding (DB) and examine the time trend of the incidence. Furthermore to study prognosis with regard to therapy and rebleeding. METHODS: A retrospective, population-based study of patients with DB in a National University Hospital from 2006 to 2016. Patients were identified in an electronically stored colonoscopy database. Definite diverticular bleeding was defined as active bleeding, a nonbleeding visible vessel or adherent clot. Presumptive diverticular bleeding was defined as acute painless rectal bleeding leading to hospitalization with visible diverticula but no evidence of bleeding and no other colonic lesions or bleeding sites identified on endoscopy. A 30-day re-bleeding was determined after discharge. RESULTS: A total of 3683 colonoscopy reports were reviewed, including 345 patients (males 51%) with presumptive 95% (n = 327) or definitive 5% (n = 18) diverticular bleeding. Overall 96% were treated conservatively, 3% endoscopically and 0.3% surgically. Only 5.8% of patients had a 30-day rebleed. After exclusion, 315 patients were included in the incidence calculations. The mean cumulative incidence of diverticular bleeding was 14/100,000 inhabitants per year. A time trend analysis of the incidence of DB revealed no significant change in incidence during the study period. CONCLUSIONS: The mean incidence of colonic diverticular bleeding was found to be approximately 14 cases per 100,000 inhabitants and year. The incidence does not seem to have changed in the past decade. The vast majority of patients with diverticular bleeding did not require endoscopic therapy and could be managed with conservative treatment

Acute gastrointestinal bleeding among patients on antiplatelet and anticoagulant therapy after percutaneous coronary intervention.

To access publisher's full text version of this article click on the hyperlink belowBackground: Patients undergoing percutaneous coronary intervention (PCI) require dual antiplatelet therapy and some require additional anticoagulation. We aimed to investigate the incidence of acute gastrointestinal bleeding (AGIB) among PCI patients receiving antiplatelet and anticoagulant therapy. Methods: A population-based study that included all patients undergoing PCI during 2008-2016 in Iceland. Data from the Icelandic Medicines Registry were obtained on all outpatient prescriptions 1 year after first PCI. Patients receiving single or dual-antiplatelet therapy with or without anticoagulation cotherapy were analyzed. Rehospitalization for AGIB and endoscopic data were obtained within the 12-month follow-up period. Results: A total of 5166 patients (male 75%) underwent PCI during the study period. The incidence of AGIB was 1% (54/5166) per year. The mean age among non-bleeders 65 (±11) years was lower than among bleeders 69 (±9) years (p = .002). The proportion of acute upper GIB (AUGIB) was 56%, whereas lower GIB occurred in 44%. Overall, 41% with AUGIB had PPIs compared to 39% of non-bleeders (NS). The incidence of AGIB among patients on single antiplatelet therapy combined with an anticoagulant was 2.5% compared to 0.9% among those on single antiplatelet treatment alone (p = .028). The number needed to harm (NNH) for treatment with single antiplatelet therapy and anticoagulant therapy compared to single antiplatelet therapy was 62 but no deaths related to AGIB. Conclusions: The 1-year incidence of AGIB was low with no mortality. Bleeding risk was found to be higher among patients on single antiplatelet therapy combined with anticoagulant therapy compared to patients on single antiplatelet therapy alone. Keywords: Acute gastrointestinal bleeding; anticoagulant therapy; antiplatelet therapy; dual antiplatelet therapy; incidence; number needed to harm; percutaneous coronary intervention

The incidence and outcome of ischemic colitis in a population-based setting.

To access publisher's full text version of this article click on the hyperlink belowPopulation-based studies on patients with ischemic colitis (IC) are limited. We aimed to determine the incidence, risk factors and outcome of patients with IC.A retrospective nationwide study was conducted on adult patients with histologically confirmed IC in 2009-2013 in Iceland. IC patients were matched for age and gender with patients hospitalized with lower gastrointestinal bleeding. Data were collected on clinical presentation, comorbidities, smoking habits, management and outcome.Eighty-nine patients, 61 (69%) females and mean age of 65 years (±17), fulfilled the predetermined criteria. Females were older than males, 68 years (±14) vs. 59 years (±20) (p = .0170). The mean cumulative incidence was 7.3 cases per 100,000 inhabitants. A total of 57 (64%) patients presented with abdominal pain, hematochezia and diarrhea. IC was localized in the left colon in 78 (88%) patients. Overall, 62 (70%) patients had cardiovascular disease vs. 53 (60%) of control group (NS) and 55 (62%) had a history of smoking vs. 53 (60%) in control group (NS). Ten (11%) patients required surgery and/or died within 30-days from hospital admission. At the end of follow-up, 7 (9%) patients had experienced recurrence of IC with an estimated 3-year recurrence rate of 15%.IC is a common clinical phenomenon that affects a wide range of age groups, but is most prominent among elderly women. It typically presents with a clinical triad of abdominal pain, hematochezia and diarrhea. Most cases are mild and self-limiting with a good prognosis

Helicobacter pylori infection in Icelandic children.

To access publisher's full text version of this article click on the hyperlink belowThe prevalence of Helicobacter pylori (HP) infection is decreasing in the western world. The seroprevalence among 25-50-year-old Icelandic adults was recently shown to be 30-40%. Information on the seroprevalence in Nordic children is limited. We aimed at ascertaining the infection prevalence among healthy Icelandic children.The infection status in stored frozen blood samples from two cross-sectional studies on the health of 7-9-year-old children (n = 125) and 16-18-year-old adolescents (n = 80) was determined by enzyme-linked immunosorbent assay (ELISA). Information on family demographics and GI symptoms was obtained by standardized questionnaires.Overall, 3.4% (7/205) of the children were infected with H. pylori. The prevalence was 2.6% (5/190), missing data n = 3, among children with both parents born in a low prevalence country compared to 17% (2/12) among those with at least one parent born in a high prevalence area (p = .026). When at least one parent was born in a high prevalence country, the odds ratio for being H. pylori seropositive was 2.2 (95% CI, 1.02-54.67), when adjusted for the educational status of the mother. There was no significant association between H. pylori infection and gastrointestinal symptoms.Prevalence of H. pylori infection in Iceland has become very low, suggesting a great reduction in transmission from older generations. There was an association between H. pylori infection and origin from high prevalence areas but not with gastrointestinal symptoms. The results mirror recent studies of children of Scandinavian ancestry