Geochemistry and speciation of Fe(II) and Fe(III) in natural geothermal water, Iceland

The geochemistry of Fe(II) and Fe(III) was studied in natural geothermal waters in Iceland. Samples of surface and spring water and sub-boiling geothermal well water were collected and analyzed for Fe(II), Fe(III) and Fetotal concentrations. The samples had discharge temperatures in the range 27–99 °C, pH between 2.46 and 9.77 and total dissolved solids 155–1090 mg/L. The concentrations of Fe(II) and Fe(III) were determined in the <0.2 μm filtered and acidified fraction using a field-deployed ion chromatography spectrophotometry (IC-Vis) method within minutes to a few hours of sampling in order to prevent post-sampling changes. The concentrations of Fe(II) and Fe(III) were <0.1–130 μmoL/L and <0.2–42 μmoL/L, respectively. In-situ dialysis coupled with Fe(II) and Fe(III) determinations suggest that in some cases a significant fraction of Fe passing the standard <0.2 μm filtration method may be present in colloidal/particulate form. Therefore, such filter size may not truly represent the dissolved fraction of Fe but also nano-sized particles. The Fe(II) and Fe(III) speciation and Fetotal concentrations are largely influenced by the water pH, which in turn reflects the water type formed through various processes. In water having pH of ∼7–9, the total Fe concentrations were <2 μmoL/L with Fe(III) predominating. With decreasing pH, the total Fe concentrations increased with Fe(II) becoming increasingly important and predominating at pH < 3. In particular in waters having pH ∼6 and above, iron redox equilibrium may be approached with Fe(II) and Fe(III) possibly being controlled by equilibrium with respect to Fe minerals. In many acid waters, the Fe(II) and Fe(III) distribution may not have reached equilibrium and be controlled by the source(s), reaction kinetics or microbial reactions

School engagement and intentional self-regulation : a reciprocal relation in adolescence

The importance of school engagement (i.e., the willingness to engage in learning) for school success, such as good academic achievement and low dropout rates, has been well established. At the same time, intentional selfregulation (ISR; i.e., the ability to set, prioritize, and obtain long-term goals) has been shown to be a precursor, mediator, and outcome of school engagement. However, the relation between school engagement and ISR during adolescence is poorly understood. In this research, I explored the reciprocal relation between school engagement and ISR during adolescence. This study had three goals. The first goal was to further the development of a valid measure of ISR for use with adolescents. The second goal was to contribute to the development of a valid measure of school engagement for use with adolescents. The third goal, which best captures the main purpose of the study, was to examine the hypothesized reciprocal relation of school engagement and ISR during the last two years of compulsory school in Iceland. The results from the development and adaptation of the school engagement and ISR measures were published in two journal articles based on four waves of data collected at the beginning and end of Grades 9 and 10 with a longitudinal sample of 561 youth in Iceland (46% girls, Mage at Wave 1 = 14.3 years, SD = 0.3). The third and final manuscript, based on data from the same longitudinal sample, supported the reciprocal relations of school engagement and ISR during adolescence after controlling for gender, academic achievement, and parent’s education. Furthermore, the results indicated decreased stability of both school engagement and ISR during the observed period. The decreasing stability is consistent with theories that present school engagement and ISR as malleable constructs that are open to contextual conditions. The reciprocal relations between school engagement and ISR support hypotheses that ISR skills are a key element in the promotion of school engagement. Keywords: intentional self-regulation, school engagement, positive youth development, adolescence, SOC.Virk þátttaka í skólastarfi (e. school engagement; skuldbinding til náms) er mikilvæg fyrir farsæla skólagöngu en sýnt hefur verið fram á skýr tengsl virkrar þátttöku í skólastarfi og jákvæðra þátta eins og t.d. hárra einkunna og lítillar hættu á brottfalli. Á sama tíma hefur verið sýnt fram á að sjálfstjórnun (e. intentional self regulation; hæfileikinn til að setja sér, forgangsraða og ná langtímamarkmiðum) spáir fyrir, miðlar og verður fyrir áhrifum af virkri þátttöku nemenda. Þrátt fyrir það er lítið vitað í hvaða röð þessi tengsl eiga sér stað á unglingsárum. Í þessari rannsókn kannaði ég möguleikann á hvort að jákvætt gagnvirkt samband gæti verið til staðar á milli virkrar þátttöku nemenda og sjálfstjórnunar á unglingsárum. Markmiðum rannsóknarinnar var skipt í þrennt. Fyrsta markmiðið var að auka við fyrirliggjandi þekkingu á því hvernig mæla má sjálfstjórnun á unglingsárum. Annað markmiðið var að auka við fyrirliggjandi þekkingu á því hvernig mæla má virka þátttöku í skólastarfi á unglingsárum. Þriðja markmiðið var að prófa tilgátuna um jákvætt gagnvirkt samband milli virkrar þátttöku nemenda og sjálfstjórnunar síðustu tvö ár grunnskólans. Niðurstöður úr aðlögun og þróun mælitækjanna á virkri þátttöku nemenda og sjálfstjórnun voru birtar í tveimur tímaritsgreinum sem byggðu á langtímagögnum sem safnað var frá 561 unglingi (46% stelpur, Maldur við byrjun 9. bekkjar = 14,3 ár, Staðalfrávik = 0,3) við upphaf og lok 9. og 10. bekkjar. Niðurstöður úr lokagrein rannsóknarinnar byggðu á sömu langtímagögnum og studdu megintilgátuna um jákvætt gagnvirkt langtímasamband milli virkrar þátttöku og sjálfstjórnunar eftir að stjórnað hafði verið fyrir áhrifum kyns, fyrri námsárangurs og menntunar foreldra. Að auki sýndu niðurstöðurnar minnkandi stöðugleika virkar þátttöku og sjálfstjórnunar eftir því sem leið að lokum grunnskólans. Minnkandi stöðugleiki á tímabilinu er í samræmi við kenningar sem lýsa virkri þátttöku nemenda og sjálfstjórnun sem mótanlegum þáttum. Sambandið milli virkrar þátttöku nemenda og sjálfstjórnunar styður við tilgátur sem sýna sjálfstjórnun sem lykilhugtak í stuðningi við virka þátttöku í skólastarfi

Changes in attitudes of Icelandic adolescents towards democracy in the classroom over a five-year period

Eitt af meginmarkmiðum núgildandi aðalnámskrár (Mennta- og menningarmálaráðuneytið, 2011/2013) er að búa nemendur undir þátttöku í lýðræðislegu samfélagi. Samkvæmt þessu á grunnskólinn að vera sá staður sem veitir nemendum svigrúm til að öðlast reynslu af lýðræðislegu starfi og vera þátttakendur í því. Markmið þessarar rannsóknar var að kanna mögulegar breytingar á viðhorfum nemenda í þessum efnum yfir fimm ára tímabil, 2010 til 2015. Tveir hópar nemenda í 6.–10. bekk (Nalls = 627) voru spurðir um afstöðu sína til lýðræðis og lýðræðisþátttöku með fimm ára millibili. Rannsóknin var gerð í samvinnu við tíu skóla sem söfnuðu gögnum við reglubundið sjálfsmat. Niðurstöður sýna að viðhorf nemenda til lýðræðis í grunnskólum á Íslandi og lýðræðisþátttaka virðist hafa tekið mjög litlum breytingum á framangreindu tímabili. Engar breytingar var að finna á því sem kallað hefur verið frjálslynd lýðræðissjónarmið, svo sem tjáningarfrelsi og samkeppni í skólastofunni. Aftur á móti mátti greina smávægilega jákvæða breytingu á viðhorfum til þess sem kallað hefur verið samstarfslýðræði, þ.e. til þátttöku og samvinnu. Mikilvægi lýðræðisþátttöku að mati nemendanna virtist dala lítillega yfir þetta fimm ára tímabil. Niðurstöðurnar voru bornar saman við danska rannsókn frá árinu 2001 sem þessi rannsókn tók mið af. Enginn afgerandi munur fannst á viðhorfum dönsku og íslensku ungmennanna. Þó virtust frjálslynd lýðræðissjónarmið vera traustari hjá dönsku ungmennunum.The Icelandic national curriculum guide for compulsory schools published in 2011 specially emphasized the importance of preparing students for active participation in a democratic society: “It is expected that children and youth learn democracy by learning about democracy in a democracy” (Mennta- og menningarmálaráðuneytið, p. 19). Democracy was furthermore emphasized as one of six fundamental pillars of the Icelandic education system together with literacy, sustainability, health and welfare, human rights, equality, and creativity. Accordingly, knowledge about changes in attitudes towards democracy and democratic participation since the introduction of this new conception in 2011 is of importance. The increased emphasis on issues related to democracy introduced in the Icelandic national curriculum guide for compulsory schools were to be fully implemented in 2013. Studies on how Icelandic students are prepared for an active participation in the constantly changing democratic society are few and far between. Therefore, the results of this study can be considered of importance for education stakeholders such as teachers, parents, students, and scholars. The theoretical model used in the study is based on the works of Danish researchers (Jacobsen, Jensen, Madsen, Sylvestersen, & Vincent, 2004), where democratic perspectives in a Western tradition are conceived as liberal democracy (e.g., emphasizing the rights of the individual) and republican democracy (e.g., emphasizing solidarity). According to the model, both perspectives need to be in place for a democracy to function, and it is in the tension between these two perspectives a democratic process becomes active. The goal of this study is to contribute to an increased theoretical and empirical knowledge about democratic processes and democratic participation in public schools. The research was intended to detect possible changes in the responses of children to questions related to liberal and republican democracy after the full implementation of the Icelandic national curriculum guide from 2011. The goals of the study were approached by asking two groups of children in Grades 6 through 10 (Ntotal = 627) about their attitudes towards democracy and democratic participation in the classroom. The first data collection was conducted in 2010 and the second data collection was conducted in 2015. The study was conducted in collaboration with 10 schools that carried out the data collection as a part of their own internal evaluation. The results show that attitudes towards democracy and democratic participation over the above depicted period had changed remotely during the five-year period. No changes were found in attitudes related to a liberal democracy. A slight positive change was detected regarding opportunities for participation and collaboration in a republican democracy. However, the importance of democratic participation showed a slight decline during this five-year period. According to the model of Jacobsen et. al. (2004) one of the prerequisites for liberal democracy is individuality. A comparison with Danish result from 2001 showed that about 61% of the Danish adolescents indicated that it was very important to “be the way they are” but only 47% of the Icelandic adolescents responded the same way in 2015. These results were in accordance with other manifestations of liberal democracy in the survey, which seemed stronger among the Danish adolescents. The limited change in the attitudes of adolescents towards democracy and democratic participation raises questions about whether compulsory schools had the resources to implement the changes in policy recommended by the 2011 national curriculum guide. More research is needed to explore what was done in schools to increase democracy in the classroom during the 2011-2013 implementation period. Furthermore, it is important to conduct further research to identify efficient ways for teachers and school administrators to meet the policy recommendation for an increased emphasis of democracy in Icelandic classrooms. Finally, comparison with results from other countries give reason to conduct more research on manifestations of liberal democracy (e.g., opportunities for an open and democratic discussion; respect for individuality) among Icelandic adolescents.Peer Reviewe

Host-Parasite Interactions and Population Dynamics of Rock Ptarmigan

Populations of rock ptarmigan (Lagopus muta) in Iceland fluctuate in multiannual cycles with peak numbers c. every 10 years. We studied the ptarmigan-parasite community and how parasites relate to ptarmigan age, body condition, and population density. We collected 632 ptarmigan in northeast Iceland in early October from 2006 to 2012; 630 (99.7%) were infected with at least one parasite species, 616 (98%) with ectoparasites, and 536 (85%) with endoparasites. We analysed indices for the combined parasite community (16 species) and known pathogenic parasites, two coccidian protozoans Eimeria muta and Eimeria rjupa, two nematodes Capillaria caudinflata and Trichostrongylus tenuis, one chewing louse Amyrsidea lagopi, and one skin mite Metamicrolichus islandicus. Juveniles overall had more ectoparasites than adults, but endoparasite levels were similar in both groups. Ptarmigan population density was associated with endoparasites, and in particular prevalence of the coccidian parasite Eimeria muta. Annual aggregation level of this eimerid fluctuated inversely with prevalence, with lows at prevalence peak and vice versa. Both prevalence and aggregation of E. muta tracked ptarmigan population density with a 1.5 year time lag. The time lag could be explained by the host specificity of this eimerid, host density dependent shedding of oocysts, and their persistence in the environment from one year to the next. Ptarmigan body condition was negatively associated with E. muta prevalence, an indication of their pathogenicity, and this eimerid was also positively associated with ptarmigan mortality and marginally inversely with fecundity. There were also significant associations between fecundity and chewing louse Amyrsidea lagopi prevalence (negative), excess juvenile mortality and nematode Capillaria caudinflata prevalence (positive), and adult mortality and skin mite Metamicrolichus islandicus prevalence (negative). Though this study is correlational, it provides strong evidence that E. muta through time-lag in prevalence with respect to host population size and by showing significant relations with host body condition, mortality, and fecundity could destabilize ptarmigan population dynamics in Iceland.This work was supported by the Icelandic Research Fund, grant number 090207021: salary including funding of this work; Hunting Card Fund: salary including funding of this work; Landsvirkjun Energy Fund: salary and funding of this work; Institute for Experimental Pathology, Keldur, University of Iceland:Peer Reviewe

The spectral dimension of random brushes

We consider a class of random graphs, called random brushes, which are constructed by adding linear graphs of random lengths to the vertices of Z^d viewed as a graph. We prove that for d=2 all random brushes have spectral dimension d_s=2. For d=3 we have {5\over 2}\leq d_s\leq 3 and for d\geq 4 we have 3\leq d_s\leq d.Comment: 15 pages, 1 figur

Les couples homosexuels et l'enregistrement de leur union: rapprochement avec les couples hétérosexuels et recherche comparative internationale.

FDR De bescherming van fundamentele rechten in een integrerend Europa ou

Random tree growth by vertex splitting

We study a model of growing planar tree graphs where in each time step we separate the tree into two components by splitting a vertex and then connect the two pieces by inserting a new link between the daughter vertices. This model generalises the preferential attachment model and Ford's $\alpha$-model for phylogenetic trees. We develop a mean field theory for the vertex degree distribution, prove that the mean field theory is exact in some special cases and check that it agrees with numerical simulations in general. We calculate various correlation functions and show that the intrinsic Hausdorff dimension can vary from one to infinity, depending on the parameters of the model.Comment: 47 page