North-south palaeohydrological contrasts in the central Mediterranean during the Holocene: tentative synthesis and working hypotheses

On the basis of a multi-proxy approach and a strategy combining lacustrine and marine records along a north–south transect, data collected in the central Mediterranean within the framework of a collaborative project have led to reconstruction of high-resolution and well-dated palaeohydrological records and to assessment of their spatial and temporal coherency. Contrasting patterns of palaeohydrological changes have been evidenced in the central Mediterranean: south (north) of around 40° N of latitude, the middle part of the Holocene was characterised by lake-level maxima (minima), during an interval dated to ca. 10 300–4500 cal BP to the south and 9000–4500 cal BP to the north. Available data suggest that these contrasting palaeohydrological patterns operated throughout the Holocene, both on millennial and centennial scales. Regarding precipitation seasonality, maximum humidity in the central Mediterranean during the middle part of the Holocene was characterised by humid winters and dry summers north of ca. 40° N, and humid winters and summers south of ca. 40° N. This may explain an apparent conflict between palaeoclimatic records depending on the proxies used for reconstruction as well as the synchronous expansion of tree species taxa with contrasting climatic requirements. In addition, south of ca. 40° N, the first millennium of the Holocene was characterised by very dry climatic conditions not only in the eastern, but also in the central- and the western Mediterranean zones as reflected by low lake levels and delayed reforestation. These results suggest that, in addition to the influence of the Nile discharge reinforced by the African monsoon, the deposition of Sapropel 1 has been favoured (1) by an increase in winter precipitation in the northern Mediterranean borderlands, and (2) by an increase in winter and summer precipitation in the southern Mediterranean area. The climate reversal following the Holocene climate optimum appears to have been punctuated by two major climate changes around 7500 and 4500 cal BP. In the central Mediterranean, the Holocene palaeohydrological changes developed in response to a combination of orbital, ice-sheet and solar forcing factors. The maximum humidity interval in the south-central Mediterranean started ca. 10 300 cal BP, in correlation with the decline (1) of the possible blocking effects of the North Atlantic anticyclone linked to maximum insolation, and/or (2) of the influence of the remnant ice sheets and fresh water forcing in the North Atlantic Ocean. In the north-central Mediterranean, the lake-level minimum interval began only around 9000 cal BP when the Fennoscandian ice sheet disappeared and a prevailing positive NAO-(North Atlantic Oscillation) type circulation developed in the North Atlantic area. The major palaeohydrological oscillation around 4500–4000 cal BP may be a non-linear response to the gradual decrease in insolation, with additional key seasonal and interhemispheric changes. On a centennial scale, the successive climatic events which punctuated the entire Holocene in the central Mediterranean coincided with cooling events associated with deglacial outbursts in the North Atlantic area and decreases in solar activity during the interval 11 700–7000 cal BP, and to a possible combination of NAO-type circulation and solar forcing since ca. 7000 cal BP onwards. Thus, regarding the centennial-scale climatic oscillations, the Mediterranean Basin appears to have been strongly linked to the North Atlantic area and affected by solar activity over the entire Holocene. In addition to model experiments, a better understanding of forcing factors and past atmospheric circulation patterns behind the Holocene palaeohydrological changes in the Mediterranean area will require further investigation to establish additional high-resolution and well-dated records in selected locations around the Mediterranean Basin and in adjacent regions. Special attention should be paid to greater precision in the reconstruction, on millennial and centennial timescales, of changes in the latitudinal location of the limit between the northern and southern palaeohydrological Mediterranean sectors, depending on (1) the intensity and/or characteristics of climatic periods/oscillations (e.g. Holocene thermal maximum versus Neoglacial, as well as, for instance, the 8.2 ka event versus the 4 ka event or the Little Ice Age); and (2) on varying geographical conditions from the western to the eastern Mediterranean areas (longitudinal gradients). Finally, on the basis of projects using strategically located study sites, there is a need to explore possible influences of other general atmospheric circulation patterns than NAO, such as the East Atlantic–West Russian or North Sea–Caspian patterns, in explaining the apparent complexity of palaeoclimatic (palaeohydrological) Holocene records from the Mediterranean area.

Legal Integration of Islam: A Transatlantic Comparison

The status of Islam in Western societies remains deeply contentious. Countering strident claims on both the right and left, Legal Integration of Islam offers an empirically informed analysis of how four liberal democracies—France, Germany, Canada, and the United States—have responded to the challenge of integrating Islam and Muslim populations. Demonstrating the centrality of the legal system to this process, Christian Joppke and John Torpey reject the widely held notion that Europe is incapable of accommodating Islam and argue that institutional barriers to Muslim integration are no greater on one side of the Atlantic than the other. While Muslims have achieved a substantial degree of equality working through the courts, political dynamics increasingly push back against these gains, particularly in Europe. From a classical liberal viewpoint, religion can either be driven out of public space, as in France, or included without sectarian preference, as in Germany. But both policies come at a price—religious liberty in France and full equality in Germany. Often seen as the flagship of multiculturalism, Canada has found itself responding to nativist and liberal pressures as Muslims become more assertive. And although there have been outbursts of anti-Islamic sentiment in the United States, the legal and political recognition of Islam is well established and largely uncontested. Legal Integration of Islam brings to light the successes and the shortcomings of integrating Islam through law without denying the challenges that this religion presents for liberal societies.

Neuropsychological long-term sequelae after posterior fossa tumour resection during childhood

The importance of the cerebellum for non‐motor functions is becoming more and more evident. The influence on cognitive functions from acquired cerebellar lesions during childhood, however, is not well known. We present follow‐up data from 24 patients, who were operated upon during childhood for benign cerebellar tumours. The benign histology of these tumours required neither radiotherapy nor chemotherapy. Post‐operatively, these children were of normal intelligence with a mean IQ of 99.1, performance intelligence quotient (PIQ) of 101.3 and verbal intelligence quotient (VIQ) of 96.8. However, 57% of patients showed abnormalities in subtesting. In addition, more extensive neuropsychological testing revealed significant problems for attention, memory, processing speed and interference. Visuo‐constructive problems were marked for copying the Rey figure, but less pronounced for recall of the figure. Verbal fluency was more affected than design fluency. Behavioural deficits could be detected in 33% of patients. Attention deficit problems were marked in 12.5%, whereas others demonstrated psychiatric symptoms such as mutism, addiction problems, anorexia, uncontrolled temper tantrums and phobia. Age at tumour operation and size of tumour had no influence on outcome. Vermis involvement was related to an increase in neuropsychological and psychiatric problems. The observation that patients with left‐sided cerebellar tumours were more affected than patients with right‐sided tumours is probably also influenced by a more pronounced vermian involvement in the former group. In summary, this study confirms the importance of the cerebellum for cognitive development and points to the necessity of careful follow‐up for these children to provide them with the necessary help to achieve full integration into professional life.

Mobilities and Pottery Production Archaeological and Anthropological Perspectives

Our workshop aims at a deeper understanding of various itineraries of pottery and dif-ferent forms of human mobilities in which pottery is relevant, bringing together archae-ological and anthropological perspectives. For thousands of years, pottery has been an important part of many societies’ material culture and therefore a major research topic in both disciplines. In past and present societies the material existence of ceramic vessels is informed by various movements across time and space but also by periods of stasis: from the mo-ment of their production until their exclusion from daily practices, either disposed as waste, excluded as funerary objects or stored as collectibles. In their seemingly endless material durability, ceramic vessels might outlive their human producers, distributors or consumers and travel farther and longer. Still they are embedded in the regimes of human mobility, ranging from daily subsistence-based mobility to long-term migrations. In such processes, pottery shifts between spatial, temporal, social, economic and cultural contexts. Thereby ceramic vessels are appropriated and integrated in new contexts of action and meaning, sometimes leading to material transformations. This workshop takes place in the context of our archaeological research project „Mobili-ties, Entanglements and Transformations in Neolithic Societies on the Swiss Plateau (3900-3500 BC)“ to which our PhDs are connected. We address the above outlined topic by analysing the production of pottery. Based on dendrochronologically dated settle-ments between 3900 and 3500 BC, two regional pottery styles and their local variations are well known, Pfyn and Cortaillod. The vessels share the same habitus and were made of clays and temper deriving from the settlements’ surroundings. However, some vessels specific to other pottery styles are also present on the sites. They are characteristic for pottery styles known from more or less far off regions (Michelsberg, Munzingen or Néo-lithique Moyen Bourguignon). Some of them were travelling objects, as their non local raw materials show. Others seem to have been produced locally, pointing to long-term mobility and a change of residence from neighbouring social groups.

Evolution of colour patterns in East African cichlid fish

African cichlid fishes have undergone outbursts of explosive speciation in several lakes, accompanied by rapid radiations in coloration and ecology. Little is known about the evolutionary forces that triggered these events but a hypothesis, published by Wallace Dominey in 1984, has figured prominently. It states that the evolution of colour patterns is driven by sexual selection and that these colour patterns are important in interspecific mate choice, a combination which holds the potential for rapid speciation. Here we present phylogenetic analyses that describe major events in colour evolution and test predictions yielded by Dominey's hypothesis. We assembled information on stripe patterns and the presence or absence of nuptial coloration from more than 700 cichlid species representing more than 90 taxa for which molecular phylogenetic hypotheses were available. We show that sexual selection is most likely the selection force that made male nuptial coloration arise and evolve quickly. In contrast, stripe patterns, though phylogenetically not conserved either, are constrained ecologically. The evolution of vertical bar patterns is associated with structurally complex habitats, such as rocky substrates or vegetation. The evolution of a horizontal stripe is associated with a piscivorous feeding mode. Horizontal stripes are also associated with shoaling behaviour. Strength of sexual selection, measured in terms of the mating system (weak in monogamous, strong in promiscuous species), has no detectable effects on stripe pattern evolution. In promiscuous species the frequency of difference between sister species in nuptial hue is higher than in pair bonding and harem forming species, but the frequency of difference in stripe pattern is lower. We argue that differences between the two components of coloration in their exposure to natural selection explain their very different evolutionary behaviour. Finally, we suggest that habitat-mediated selection upon chromomotor flexibility, a special form of phenotypic plasticity found in the river-dwelling outgroups of the lake-dwelling cichlids, explains the rapid and recurrent ecology-associated radiation of stripe patterns in lake environments, a new hypothesis that yields experimentally testable predictions.

Sublimation of ice–tholins mixtures: A morphological and spectro-photometric study

Sublimation, the direct transition from solid to gas phase, is a process responsible for shaping and changing the reflectance properties of many Solar System surfaces. In this study, we have characterized the evolution of the structure/texture and of the visible and near-infrared (VIS–NIR) spectral reflectance of surfaces made of water ice mixed with analogues of complex extraterrestrial organic matter, named tholins, under low temperature (<-70° C) and pressure (10-⁵mbar) conditions. The experiments were carried out in the SCITEAS simulation setup recently built as part of the Laboratory for Outflow Studies of Sublimating Materials (LOSSy) at the University of Bern (Pommerol, A. et al. [2015a]. Planet. Space Sci. 109–110, 106–122). As the water ice sublimated, we observed in situ the formation of a sublimation lag deposit made of a water-free porous (>90% porosity) network of organic filaments on top of the ice. The temporal evolution of the tholins and water ice spectral features (reflectance at the absorption bands wavelengths, red slope, from 0.40 to 1.90lm) are analyzed throughout the sublimation of the samples. We studied how different mixtures of tholins with water (0.1 wt.% tholins as coating or inclusions within the water particles), and different ice particle sizes (4.5 ± 2.5 or 67 ± 31lm) influence the morphological and spectral evolutions of the samples. The sublimation of the ice below the mantle produces a gas flow responsible for the ejection of mm to cm-sized fragments of the deposit in outbursts-like events. The results show remarkable differences between these samples in term of mantle structure, speed of mantle building, rates and surface area of mantle ejections. These data provide useful references for interpreting remote-sensing observations of icy Solar System surfaces, in particular the activity of comet nuclei where sublimation of organic-rich ices and deposition of organic-dust particles likely play a major role. Consequently, the data presented here could be of high interest for the interpretation of Rosetta, and also New Horizons, observations.

Pits formation from volatile outgassing on 67P/Churyumov-Gerasimenko

We investigate the thermal evolution of comet 67P/Churyumov-Gerasimenko's subsurface in the Seth_01 region, where active pits have been observed by the ESA/Rosetta mission. Our simulations show that clathrate destabilization and amorphous ice crystallization can occur at depths corresponding to those of the observed pits in a timescale shorter than 67P/Churyumov-Gerasimenko's lifetime in the comet's activity zone in the inner solar system. Sublimation of crystalline ice down to such depths is possible only in the absence of a dust mantle, which requires the presence of dust grains in the matrix small enough to be dragged out by gas from the pores. Our results are consistent with both pits formation via sinkholes or subsequent to outbursts, the dominant process depending on the status of the subsurface porosity. A sealed dust mantle would favor episodic and disruptive outgassing as a result of increasing gas pressure in the pores, while high porosity should allow the formation of large voids in the subsurface due to the continuous escape of volatiles. We finally conclude that the subsurface of 67P/Churyumov-Gerasimenko is not uniform at a spatial scale of similar to 100-200 m.

Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse

Pits have been observed on many cometary nuclei mapped by spacecraft(1-4). It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments(5,6) andmodels(7,8) cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts(8,9). Alternative mechanisms like explosive activity(10) have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.