The Age and Origin of the Gelderse IJssel

Historic trading cities are located on the Gelderse IJssel and flourished in the late Middle Ages. Little is known about this river in the early Middle Ages and before, and there is considerable debate on the age and origin of the Gelderse IJssel as a Rhine distributary. A small river draining the surrounding Pleistocene uplands must have been present in the IJssel valley during most of the Holocene, but very diverse opinions exist as to when this local river became connected to the Rhine system (and thereby to a vast hinterland), and whether this was human induced or a natural process. We collected new AMS radiocarbon evidence on the timing of beginning overbank sedimentation along the lower reach of the Gelderse IJssel. Our data indicate onset of overbank sedimentation at about 950 AD in this reach. We attribute this environmental change to the establishment of a connection between the precursor of the IJssel and the Rhine system by avulsion. Analysis of previous conventional radiocarbon dates from the upper IJssel floodplain yields that this avulsion may have started ~600 AD. Our results contradict earlier suppositions, based on interpretation of archaeological data and historical accounts, that the Gelderse IJssel is much older and originated as a canal, dug under supervision of the Roman general DrususThe Gelderse IJssel is the third major distributary of the Rhine in the Netherlands and diverts on average similar to 15% of the Rhine discharge northward. Historic trading cities are located on the Gelderse IJssel and flourished in the late Middle Ages. Little is known about this river in the early Middle Ages and before, and there is considerable debate on the age and origin of the Gelderse IJssel as a Rhine distributary. A small river draining the surrounding Pleistocene uplands must have been present in the IJssel valley during most of the Holocene, but very diverse opinions exist as to when this local river became connected to the Rhine system (and thereby to a vast hinterland), and whether this was human induced or a natural process. We collected new AMS radiocarbon evidence on the timing of beginning overbank sedimentation along the lower reach of the Gelderse IJssel. Our data indicate onset of overbank sedimentation at about 950 AD in this reach. We attribute this environmental change to the establishment of a connection between the precursor of the IJssel and the Rhine system by avulsion. Analysis of previous conventional radiocarbon dates from the upper IJssel floodplain yields that this avulsion may have started similar to 600 AD. Our results contradict earlier suppositions, based on interpretation of archaeological data and historical accounts, that the Gelderse IJssel is much older and originated as a canal, dug under supervision of the Roman general Drusus

Family motivational intervention for reducing cannabis use in recent-onset schizophrenia

Cannabis use in highly prevalent among young adults with recent-onset schizophrenia and has been associated with an adverse course of the illness. Despite these association, the evidence for effective interventions for treating cannabis use in patients with psychosis is limited. This thesis focuses on the short and long term effects of a novel family-based intervention for schizophrenia, called Family Motivational Intervention (FMI); a training in interactions skills and motivational interviewing skills for parents to reduce cannabis use in young adults with recent-onset schizophrenia. In a randomized controlled trial (RCT) we demonstrated that FMI was significant more effective than Routine Family Support (RFS) in reducing the frequency and quantity of cannabis use in patients at 3- and 15-month follow-up. Findings were inconsistent with regard to the long-term superiority of FMI over RFS in reducing parents’ levels of distress and sense of burden. In the trial we also demonstrated that FMI is a feasible training method for increasing motivational interviewing skills in parents

Myrica migration in the Holocene

Already in the Boreal Myrica gale (gale; bog myrtle) formed a part of the vegetation of the Drents-Friese Plateau in the Northern Netherlands. During the Subboreal gale became more important. Due to human activity especially in the borderzones of the rivers and streams which drained the Pleistocene grounds of Friesland and Utrecht, the area of Myrica increased. From these borderzones it moved up very quickly to the peat areas of the coastal zone. Once settled in the bogs gale dominated at some places the vegetation of the coastal plain of Friesland and Noord-Holland. Under watery conditions gale produces macroscopic well recognisable rootlets with verrucous tubers. The presence of the coastal barriers and the dunes in the Western Netherlands gives Myrica the opportunity to be an important element of the peat bogs, till the large-scale land reclamation started (± 800 à 1000 AD). In Friesland Myrica is on the way down already during the Roman period. Salt water and long-term drainage caused by the digging of ditches (land reclamation) resulted in the decrease of the area of Myrica

Van hoog naar laag: migratie van Myrica gale in het Holoceen

Myrica maakt al in het Boreaal deel uit van de vegetatie van het Drents-Friese Plateau. Het aandeel van deze soort in de vegetatie neemt, gezien de hogere pollenwaarden, toe in het Subboreaal. Met name in de randzones van de rivier- en beekdalen (zoomvegetatie) van het Plateau lijkt ingrijpen van de mens te hebben geleid tot vergroting van het areaal. In de tweede helft van het Holoceen breidt Myrica vanuit de zoomvegetatie van de hogere zandgronden zijn areaal ook uit naar het veen van het kustgebied. In Noord-Holland leidt het ontstaan van strandwallen en duinen tot afscherming van de directe invloed van de zee, waardoor Myrica de kans krijgt zijn biotoop vanuit de randzone van de Utrechtse Heuvelrug naar het westen uit te breiden. In Noordwest-Friesland (Noord-Nederland) ontbreken strandwallen en duinen. De kust blijft er open. Toch vindt er afscherming van de zee plaats, gezien de aanwezigheid van Myrica (wortels met knolletjes, veroorzaakt door een bacterie) in het hoogveen. Het aanwezige (pleistocene) reliëf, de afnemende stijging van de zeespiegel, het ontstaan van hoogveenkussens en in het bijzonder de vorming van een waddengebied met kwelders hebben bij het ontstaan van de afscherming een rol gespeeld. Al voor de Romeinse Tijd is Myrica in de veengebieden van het noorden van Friesland op zijn retour. Daarentegen weet Myrica zich in Noord-Holland langer te handhaven. In beide gebieden vormt Myrica, bij hoge waterstanden in het hoogveen, vanuit de winterknoppen uitlopers (met knolletjes). De hogere waterstanden zijn het gevolg van natuurlijke omstandigheden, zoals zeespiegelstijging en klink.Bij langdurige ontwatering van het veen als gevolg van het ontstaan van een waddengebied met bijbehorende geulen (Noordwest-Friesland) en/of de aanleg van afwateringssystemen zoals (ontginning)sloten (Noord-Holland), verdwijnt Myrica.Already in the Boreal Myrica gale (gale; bog myrtle) formed a part of the vegetation of the Drents-Friese Plateau in the Northern Netherlands. During the Subboreal gale became more important. Due to human activity especially in the borderzones of the rivers and streams which drained the Pleistocene grounds of Friesland and Utrecht, the area of Myrica increased. From these borderzones it moved up very quickly to the peat areas of the coastal zone. Once settled in the bogs gale dominated at some places the vegetation of the coastal plain of Friesland and Noord-Holland. Under watery conditions gale produces macroscopic well recognisable rootlets with verrucous tubers. The presence of the coastal barriers and the dunes in the Western Netherlands gives Myrica the opportunity to be an important element of the peat bogs, till the large-scale land reclamation started (± 800 à 1000 AD). In Friesland Myrica is on the way down already during the Roman period. Salt water and long-term drainage caused by the digging of ditches (land reclamation) resulted in the decrease of the area of Myrica

Verdronken dekzandgronden in Zuidelijk Flevoland (archeologische opgraving `A27-Hoge Vaart'); een interdisciplinaire studie naar de veranderingen van bodem en landschap in het Mesolithicum en Vroeg-Neolithicum

Bij een archeologische opgraving in Zuidelijk Flevoland is de bodemvorming en de vegetatieontwikkeling van een dekzandrug langs een diepe holocene stroomgeul onderzocht. Bodem en vegetatie kwamen in de loop van het Atlanticum onder sterke invloed van het grondwater te staan door de snel rijzende zeespiegel. Het landschap veranderde in een zoetwatergetijdengebied met sterk fluctuerende waterstanden. De oorspronkelijke bruine bosgrond degradeerde hierdoor tot een sterk verzuurde en hydromorfe zandgrond. Tussen 6000 en 5500 BP steeg de gemiddelde grondwaterstand in de dekzandrug met een snelheid van minstens 15 cm per eeuw. Rond 5500 BP werd de dekzandrug volledig overgroeid door rietveen

Landscape-scale drivers of glacial ecosystem change in the montane forests of the eastern Andean flank, Ecuador

Understanding the impact of landscape-scale disturbance events during the last glacial period is vital in accu- rately reconstructing the ecosystem dynamics of montane environments. Here, a sedimentary succession from the tropical montane cloud forest of the eastern Andean flank of Ecuador provides evidence of the role of non- climate drivers of vegetation change (volcanic events, fire regime and herbivory) during the late-Pleistocene. Multiproxy analysis (pollen, non-pollen palynomorphs, charcoal, geochemistry and carbon content) of the se- diments, radiocarbon dated to ca. 45–42 ka, provide a snap shot of the depositional environment, vegetation community and non-climate drivers of ecosystem dynamics. The geomorphology of the Vinillos study area, along with the organic‐carbon content, and aquatic remains suggest deposition took place near a valley floor in a swamp or shallow water environment. The pollen assemblage initially composed primarily of herbaceous types (Poaceae-Asteraceae-Solanaceae) is replaced by assemblages characterised by Andean forest taxa, (first Melastomataceae-Weinmannia-Ilex, and later, Alnus-Hedyosmum-Myrica). The pollen assemblages have no modern analogues in the tropical montane cloud forest of Ecuador. High micro-charcoal and rare macro-charcoal abundances co-occur with volcanic tephra deposits suggesting transportation from extra-local regions and that volcanic eruptions were an important source of ignition in the wider glacial landscape. The presence of the coprophilous fungi Sporormiella reveals the occurrence of herbivores in the glacial montane forest landscape. Pollen analysis indicates a stable regional vegetation community, with changes in vegetation population co- varying with large volcanic tephra deposits suggesting that the structure of glacial vegetation at Vinillos was driven by volcanic activity

Using Bayes Factors for testing hypotheses about intervention effectiveness in addictions research

Background and aims: It has been proposed that more use should be made of Bayes factors in hypothesis testing in addiction research. Bayes factors are the ratios of the likelihood of a specified hypothesis (e.g. an intervention effect within a given range) to another hypothesis (e.g. no effect). They are particularly important for differentiating lack of strong evidence for an effect and evidence for lack of an effect. This paper reviewed randomized trials reported in Addiction between January and June 2013 to assess how far Bayes factors might improve the interpretation of the data. Methods: Seventy-five effect sizes and their standard errors were extracted from 12 trials. Seventy-three per cent (n = 55) of these were non-significant (i.e. P > 0.05). For each non-significant finding a Bayes factor was calculated using a population effect derived from previous research. In sensitivity analyses, a further two Bayes factors were calculated assuming clinically meaningful and plausible ranges around this population effect. Results: Twenty per cent (n = 11) of the non-significant Bayes factors were 3. The other 76.4% (n = 42) of Bayes factors were between ⅓ and 3. Of these, 26 were in the direction of there being an effect (Bayes factor > 1 and ⅓); and for four there was no evidence either way (Bayes factor = 1). In sensitivity analyses, 13.3% of Bayes Factors were 3, showing good concordance with the main results. Conclusions: Use of Bayes factors when analysing data from randomized trials of interventions in addiction research can provide important information that would lead to more precise conclusions than are obtained typically using currently prevailing methods

Subglacial Meltwater Supported Aerobic Marine Habitats During Snowball Earth

The Earth’s most severe ice ages interrupted a crucial interval in eukaryotic evolution with widespread ice coverage during the Cryogenian Period (720 to 635 Ma). Aerobic eukaryotes must have survived the “Snowball Earth” glaciations, requiring the persistence of oxygenated marine habitats, yet evidence for these environments is lacking. We examine iron formations within globally distributed Cryogenian glacial successions to reconstruct the redox state of the synglacial oceans. Iron isotope ratios and cerium anomalies from a range of glaciomarine environments reveal pervasive anoxia in the ice-covered oceans but increasing oxidation with proximity to the ice shelf grounding line. We propose that the outwash of subglacial meltwater supplied oxygen to the synglacial oceans, creating glaciomarine oxygen oases. The confluence of oxygen-rich meltwater and iron-rich seawater may have provided sufficient energy to sustain chemosynthetic communities. These processes could have supplied the requisite oxygen and organic carbon source for the survival of early animals and other eukaryotic heterotrophs through these extreme glaciations

Hydrothermal replacement of biogenic and abiogenic aragonite by Mg-carbonates – Relation between textural control on effective element fluxes and resulting carbonate phase

Dolomitization, i.e., the secondary replacement of calcite or aragonite (CaCO3) by dolomite (CaMg[CO3]2), is one of the most volumetrically important carbonate diagenetic processes. It occurs under near surface and shallow burial conditions and can significantly modify rock properties through changes in porosity and permeability. Dolomitization fronts are directly coupled to fluid pathways, which may be related to the initial porosity/permeability of the precursor limestone, an existing fault network or secondary porosity/permeability created through the replacement reaction. In this study, the textural control on the replacement of biogenic and abiogenic aragonite by Mg-carbonates, that are typical precursor phases in the dolomitization process, was experimentally studied under hydrothermal conditions. Aragonite samples with different textural and microstructural properties exhibiting a compact (inorganic aragonite single crystal), an intermediate (bivalve shell of Arctica islandica) and open porous structure (skeleton of coral Porites sp.) were reacted with a solution of 0.9 M MgCl2 and 0.015 M SrCl2 at 200 °C. The replacement of aragonite by a Ca-bearing magnesite and a Mg-Ca carbonate of non-stoichiometric dolomitic composition takes place via a dissolution-precipitation process and leads to the formation of a porous reaction front that progressively replaces the aragonite precursor. The reaction leads to the development of porosity within the reaction front and distinctive microstructures such as gaps and cavities at the reaction interface. The newly formed reaction rim consists of chemically distinct phases separated by sharp boundaries. It was found that the number of phases and their chemical variation decreases with increasing initial porosity and reactive surface area. This observation is explained by variations in effective element fluxes that result in differential chemical gradients in the fluid within the pore space of the reaction rim. Observed reaction rates are highest for the replacement of the initially highly porous coral and lowest for the compact structure of a single aragonite crystal. Therefore, the reaction progress equally depends on effective element fluxes between the fluid at the reaction interface and the bulk solution surrounding the test material as well as the reactive surface area. This study demonstrates that the textural and microstructural properties of the parent material have a significant influence on the chemical composition of the product phase. Moreover, our data highlight the importance of effective fluid-mediated element exchange between the fluid at the reaction interface and the bulk solution controlled by the local microstructure

Testate amoebae in pollen slides

Among the non-pollen micro-fossils commonly encountered in Quaternary sediment samples prepared for pollen analysis are many shells of testate amoebae. Testate amoebae are eukaryotic micro-organisms which are increasingly used in ecological and palaeoecological studies, particularly as indicators of hydrological change in Sphagnum-dominated peatlands. In this study we address the extent to which testate amoebae are used in palynological research, the key challenges to more widespread use, and the extent to which ecological information is retained in the testate amoeba assemblages of standard palynological slides. To achieve this we review the literature on the use of testate amoebae in palynology, compare testate amoeba records produced by palynological and water-based preparation methods and carry out simulations using previously-derived datasets. Our results show that testate amoebae are widely encountered in Quaternary palynological studies, primarily in peatlands, but the information which they can provide is undermined by limited taxonomic knowledge. Many taxa are destroyed in pollen preparations, but for taxa that are retained patterns of abundance parallel those determined using water-based preparation methods. Although the loss of sensitive taxa limits the ecological information contained in testate amoeba assemblages the information preserved is likely to be useful in a multiproxy approach to palaeoenvironmental reconstruction. To help improve taxonomic awareness and encourage the use of testate amoebae in palynology we present a basic introduction to testate amoeba taxonomy and a guide to the taxonomic literature