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Object detection performed by Autonomous Vehicles (AV)s is a crucial operation that comes ahead of various autonomous driving tasks, such as object tracking, trajectories estimation, and collision avoidance. Dynamic road elements (pedestrians, cyclists, vehicles) impose a greater challenge due to their continuously changing location and behaviour. This paper presents a comprehensive review of the state-of-the-art object detection technologies focusing on both the sensory systems and algorithms used. It begins with a brief introduction on the autonomous driving operations and challenges. Then, different sensory systems employed on existing AVs are elaborated while illustrating their advantages, limitations and applications. Also, sensory systems employed by different research are reviewed. Moreover, due to the significant role Deep Neural Networks (DNN)s are playing in object detection tasks, different DNN-based networks are also highlighted. Afterwards, previous research on dynamic objects detection performed by AVs are reviewed in tabular forms. Finally, a conclusion summarizes the outcomes of the review and suggests future work towards the development of vehicles with higher automation levels.

The existence of former glacial lakes remains poorly documented in the remote regions of the Canadian Shield where the dense forest cover and poor access complicate classical mapping methods. Here we use a high-resolution Digital Elevation Model (DEM; 1 m/pixel) based on LiDAR data to map Quaternary deposits and landforms in the vicinity of the Gouin reservoir in the Laurentian Highlands of Quebec (Canada). A total of 598 raised shorelines were identified, providing new evidence for the presence of a large proglacial lake – Lake Obedjiwan – that formed in front of the northward retreating Laurentide ice sheet margin during the last deglaciation, a few kilometers east of the larger Lake Ojibway that covered extensive areas in northern Ontario and Quebec. The elevation of shorelines outlines a tilted water plane that depicts the influence of the glacio-isostatic adjustment across the basin, with shorelines ranging from 409 m in the south to 439 m in the north. The calculated uplift gradient of 0.78 m/km indicates that the lake developed during the early stages of the deglaciation. Our reconstruction constrains the full areal extent and maximum elevation of the lake, which covered an area of 1800 km2 and reached an elevation of 450 m. It also indicates that Lake Obedjiwan developed independently from Lake Ojibway. The lake-surface elevation was controlled by an outlet located in the southeastern part of the basin where a topographic depression lying at an elevation of 390 m routed meltwater overflow southward through the Saint-Maurice River and into the St. Lawrence River. Another important outlet is located in the northernmost part of the basin and ice retreat beyond this topographic depression (427 m) caused the drawdown of the Lake Obedjiwan, which drained westward into Lake Ojibway. This discharge added around 19 km3 of meltwater, an event that likely impacted the hydrological budget and sedimentology of Lake Ojibway. The results suggest that other glacial lakes probably developed along the southern LIS ice margin and that the approach developed in this study may contribute to the refinement of their areal coverage and improve paleogeographic reconstructions.

Bedrock in arctic and subarctic regions is covered by glacial deposits making the discovery of new mineral deposits difficult. Indicator mineral methods using glacial sediment have thus been developed for mineral exploration in such drift-covered areas. However, sulfide indicator minerals have been under utilized because it was thought that they would not survive glacial transport and post-depositional oxidation during soil formation. In this contribution we show that the 0.25–1 mm non-ferromagnetic heavy mineral concentrates of Quaternary till and esker samples from the Churchill province in northern Quebec, Canada, contain thousands of pyrite and chalcopyrite grains and a few sulfarsenide grains. Accordingly, sulfide minerals do survive glacial and glaciofluvial transport, even in the relatively oxidizing environment of the eskers, and their presence indicates the potential presence of mineralized bedrock up ice. The study area is therefore ideal to test the use of sulfide mineral chemistry for mineral assessment and vectoring. The composition of the pyrite and chalcopyrite grains recovered from the glacial deposits have been determined by LA-ICP-MS and compared with known values for sulfides in magmatic and hydrothermal deposits. Although some elements (e.g. Ag, Cu, Zn, Pb, W, Ba, La, and Yb) are enriched in narrow rims on some sulfide grains, indicating their limited mobility during oxidation, most elements have not been mobilized and reflect initial sulfide compositions in bedrock sources. The binary diagram Co/Sb versus Se/As shows that most of the pyrite grains in surficial sediments are of magmatic origin although some are from hydrothermal sources. The hydrothermal pyrites are enriched in hydrothermal pathfinders (Au, Hg, Ag, Tl, Pb, Zn, Cu, and Mo). The ternary diagram Se-Cd-Ni shows that chalcopyrites from both magmatic and hydrothermal deposits are present in glacial sediments. The high Cd/Zn ratios of the hydrothermal chalcopyrites are indicative of a high crystallization temperature, typical of metamorphosed VMS or SEDEX deposits. Integrated maps combining bedrock geology, glacial transport directions, sample locations, and sulfide grain compositions and populations can be used to delineate target sectors for mineral exploration. Here sulfides have been transported over ~100 km roughly towards north, from sources in the Rachel-Laporte Zone and the Labrador Trough, where metasedimentary/metavolcanic rocks and mafic/ultramafic intrusive rocks are favorable hosts for hydrothermal and magmatic mineralization, respectively.

The last deglaciation of the Laurentide Ice Sheet in northern Quebec and Labrador led to the formation of several glacial lakes that drained into Ungava Bay and the nearby Labrador Sea. Assessing the potential impact of their drainage on ocean surface conditions and climate, however, is limited by the few existing age constraints on ice retreat and associated evolution of these lakes. Here we report 21 10Be ages from shorelines and an outburst flood landform formed by Lake Naskaupi, one of the largest glacial lakes in this region. The results indicate that the lake drained from its full extent at 8300 ± 300 a, suggesting that it may have contributed to the freshwater forcing initiated by the drainage of Lake Agassiz-Ojibway that caused the 8.2-ka cold event. Additionally, the results provide important constraints on the position of the ice margin of the Labrador Sector during its retreat across this region.

The climate variability of the last deglaciation is often linked to meltwater discharges from the melting of large ice sheets. One of the best examples comes from the drainage of glacial Lake Agassiz-Ojibway (LAO) and its attendant perturbation of the Atlantic Meridional Overturning Circulation (AMOC), which has long been held responsible for a rapid cooling at ∼8.2 ka. However, recent modeling studies have argued that a large and sustained freshwater flux linked to increased surface melt and ensuing collapse of the Laurentide Ice Sheet (LIS) dam may have formed an efficient forcing for this cooling event. Yet, empirical (geological) evidence for a long-lasting meltwater flux is still equivocal while paleoceanographic data show that the freshening of the North Atlantic around the 8.2-ka cold event is characterized by multiple freshwater pulses. Part of this uncertainty arises from the lack of constraints on the structure (number) and timing of meltwater discharges involved in the drainage of LAO, which prevents a detailed assessment of the freshwater forcing mechanisms at work and their potential impact on AMOC—an important issue given the present-day increase in the melting of the cryosphere around the North Atlantic. Here, we review 597 14C ages from marine and continental sediment archives and use 296 of these 14C ages along with LAO geomorphological and varve records to present an integrated framework constraining the timing of LAO meltwater outbursts across the final deglaciation interval. Results show that LAO drained through two distinct events: first subglacially at ∼8.22 cal ka BP and then after the breakup of the ice dam at ∼8.16 cal ka BP. These LAO meltwater discharges are coeval with two important freshwater pulses in North Atlantic sediment cores, with the largest meltwater outburst matching the onset of the 8.2 ka event in Greenland ice cores. These results suggest that, in a fast-changing ocean-climate system influenced by melting ice sheets like that of the late deglaciation, massive and short-lived freshwater injections can potentially have an impact on AMOC.

The Labrador Sector of the Laurentide Ice Sheet is characterized by a complex network of ice divides and an extensive landform record outlining two broad and opposing ice flows that are separated by a narrow Horseshoe Intersection Zone (HIZ). This geomorphic system gave rise to contrasting reconstructions, which reflect uncertainties on the temporal evolution of ice divides, the nature and age of the main landform systems and the overall pattern of ice retreat during the last deglaciation. Here, we address these issues through systematic mapping of glacial landforms and ice-flow indicators in a large area of northeastern Quebec and Labrador. The application of cosmogenic (10Be and 26Al) dating to esker-fed glaciomarine deltas and different rock surfaces brings new constraints on the chronological framework and insights on the subglacial thermal regime. Our results outline four main landform assemblages, two of which relating to a major system of opposite ice flows that delineate the position of the eastern Ancestral Labrador ice divide. Our reconstruction shows that the HIZ occurs several tens of km to the west of this divide and that these two features are genetically distinct. The HIZ relates to the late-glacial development of ice streams showing a massive convergent ice flow into Ungava Bay. The upstream extent of this ice flow system shows a strong coupling with the outline of Ungava Bay drainage divide, suggesting that the configuration of the HIZ could be the expression of a topographic control on the late-glacial ice sheet dynamics. Landforms also indicate a significant shift in the deglaciation mode, which evolved from an overall warm-based to an areally-confined cold-based ice retreat near the center of the former ice mass – a change in dynamics that also played a role in the configuration of the HIZ. Overall, areas indicative of cold-based ice conditions are limited to highly elevated terrains, thus ruling out models arguing for an extensive cold-based ice cover over Ungava Bay throughout the last deglaciation.

This investigation was prompted by an enigmatic ice-flow anomaly (Area A) on the Glacial Map of Canada which covers about 10 000 km 2 in the Hearst/Kapuskasing area of northeastern Ontario. It consists of streamlined landforms and striations indicative of a major ice flow toward 130° oriented at right angle to another toward 220°. Both are late glacial flows but long-lasting disagreement exists regarding their relative age. The analysis of aerial photographs and satellite images in conjunction with a detailed survey of bedrock cross-striated surfaces over an area of about 30 000 km 2 within and around Area A clearly indicate that the 130° flow preceded the 220° flow. The earlier conflicting interpretations within Area A are attributed mainly to the sporadic occurrence of relict striated surfaces formed by older southwestward (220°–240°) Wisconsinan ice flows that have locally escaped destruction by late glacial flows, with the result that the southwestward flows are older (Wisconsinan) at some sites and younger (late glacial 220°) at others relative to the 130° flow. When considered with other factors such as the maximum elevation reached by the youngest late glacial flow, these ice-flow relationships indicate that Area A is the outcropping southern part of a much larger ESE ice-flow system, which is probably related to a large fluted belt located to the north and that was identified as the Winisk Ice Stream. The distal part of the ice stream, except for Area A, escaped detection by remote sensing mapping methods because depositional and erosional features associated with it are masked by deposits laid down by the younger (220°, Cochrane) ice flow and/or by postglacial marine and organic deposits (or were destroyed by the younger ice flow). The only reliable indicators of the passage of the ice stream in this “buried” section are ESE relict striations crossed by SW striations. The advancing ice stream toward the ESE not only preceded the late Cochrane 220° flow but probably outlasted it, as suggested by the mapping of several thousand iceberg furrows in Quebec and Ontario, also directed toward the ESE and overprinted on flutes formed by the last glacial flow. If this interpretation is correct, this makes the Winisk Ice stream the largest terrestrial ice stream in the Hudson Bay basin. An alternative interpretation associates this fluted belt to the exposed western fringe of streamlined bedforms from a late Hudson lobe buried by younger sediments.

Glacial Lake Ojibway occupied large areas in northeastern Ontario and northwestern Quebec during the last deglaciation. Paleogeographic reconstructions depict Lake Ojibway and Lake Agassiz sharing a common water plane shortly before the final drainage of this lake ∼8200 years ago. However, the pre-drainage surface elevation and extent of this large coalesced lake is based on scattered raised shorelines in the Ojibway basin and poorly constrained geomorphological considerations, which convey large uncertainties in lake-level reconstructions and the attendant meltwater volume estimates used to assess the impact of this freshwater discharge. Here, we address this issue by using 3098 elevation measurements of shorelines mapped on a LiDAR digital terrain model covering a key area in the Ojibway basin. Our reconstruction is based on a GIS model integrating the paleotopography, which reinforces correlation of shorelines and the identification of lake levels. The spatial distribution of shoreline-elevation data points shows well-defined clusters of shorelines aligned on distinct elevation ranges that delineate three widespread lake levels, which are separated by two intervals with atypically low number of shorelines reflecting abrupt lake drawdowns. This reconstruction considerably refines the sequence in the eastern (Ojibway) basin and shows evidence for a two-step drainage of Lake Agassiz-Ojibway. The results provide constraints on the magnitude of the lake-level drops and indicate that the pre-drainage surface-elevation of Lake Agassiz-Ojibway of earlier reconstructions was likely overestimated. Accordingly, the configuration and structure of this lake stage should be re-evaluated. To that effect, the new shoreline record provides an important framework for assessing late-stage changes in lake levels across the Agassiz-Ojibway basin, which is a critical step towards the production of realistic models depicting the drainage of this large lake.

The decay of the Laurentide ice sheet southern margin during the last deglaciation led to the development of Lake Ojibway that covered large expanses of northeastern Ontario and northwestern Quebec. The history of Ojibway lake phases is poorly detailed mainly because of the physical configuration of the lake basin and the dominance of fine-grained glaciolacustrine sediments that prevent the formation of well-developed and extensive sandy strandlines. Here we use a complex sequence of relict terraces carved in glaciolacustrine rhythmites to document the evolution of Lake Ojibway in northwestern Quebec. Specifically, lake levels were constrained by measuring the elevation of 154 raised wave-cut scarps present in the eastern Lake Abitibi region. Results provide evidence for four distinct shorelines with elevations of 299, 289, 282, and 272 m (± 1 m) at the latitude of La Sarre. The highest lake level documented appears to be linked to one of the two known (Kinojevis) phases of Lake Ojibway, while the three other lake levels project well below the main outlet system that controlled the elevation of the lake during the deglaciation. The elevation, uplift gradients, and areal extent of these lower shorelines suggest that the two intermediate lake levels likely formed during late stages of the deglaciation, following abrupt drawdowns of the lake's surface. The fourth and lowest shoreline is associated with a postglacial lake that developed after the complete withdrawal of Ojibway water from the region. These low-elevation shorelines bring new evidence for significant changes in the areal extent and depth of Lake Ojibway near the end of the deglaciation. Although the origin of these late-stage phases remains unspecified, the associated drawdowns likely implied routing events into newly deglaciated regions and/or (subglacial) meltwater discharges into the North Atlantic.

Summary Noble gases, in particular 3He/4He (R) ratios, were measured together with tritium activity in groundwater from eskers and moraines of the Abitibi-Temiscamingue region of northwestern Quebec (eastern Canada). These high-latitude glaciofluvial landforms contain precious freshwater resources that need to be quantified. Here we provide estimates of residence time for groundwater in glaciofluvial sediments forming the Saint-Mathieu–Berry (SMB) and Barraute eskers, the Harricana moraine and in the underlying fractured bedrock aquifer. The 3He/4He ratios range from 0.224 ± 0.012 to 1.849 ± 0.036Ra, where Ra is the atmospheric 3He/4He ratio (1.386 × 10−6). These results suggest the occurrence of 3He produced by decay of tritium and terrigenic 4He produced by decay of U and Th. Calculated 3H/3He apparent ages of groundwater from the SMB esker and the Harricana moraine range from 6.6 ± 1.1 a to 32 ± 7.4 a. Terrigenic 4He (4Heterr) was found in the deeper wells of the SMB esker and in the wells tapping water from the deeper fractured aquifer located below the eskers and moraines and confined by postglacial clays. The amount of 4Heterr ranges from 3.4 × 10−9 to 2.2 × 10−6 cm3STP g−1 and shows a clear gradient with depth, suggesting addition of a 4Heterr flux entering the bottom of the eskers. Modeled 4Heterr fluxes range from 2.0 × 10−8 cm3STP cm−2 yr−1 at the Harricana moraine to 6.6 × 10−7 cm3STP cm−2 yr−1 in the southern section of the SMB esker. Calculated fluxes are highly variable and 5–165 times lower than the helium continental crustal flux, suggesting local helium sources, with helium being driven upward through preferential pathways such as local faults. Maximum U–Th/4He ages obtained for the groundwater in the fractured bedrock range from 1473 ± 300 a to 137 ± 28 ka, suggesting the occurrence of several generations of fossil meltwater trapped under the clay plain after the last two glaciations.

Lake Ojibway developed at the southern Laurentide Ice Sheet margin during the last deglaciation and covered vast expanses of northeastern Ontario and northwestern Quebec (Canada). The late-stage history of the lake is complex, presumably marked by a coalescence with Lake Agassiz and by late-glacial ice readvances into the basin shortly before its final drainage ∼8200 years ago. However, these events are poorly defined in the Lake Ojibway varve record. Here we present evidence for the occurrence of one major ice readvance and two distinct drainage events from two varve sequences in northwestern Quebec. The Matagami section contains 231 varves that comprise an interval recording a late-glacial (Cochrane) ice readvance. The La Reine section spans 100 varves and the base of the sequence is characterized by a set of chaotic and coarse-grained (silty) rhythmites that marks the first lake drainage. These bottom rhythmites are overlain by a set of 65 thick varves, which are in turn capped by a thick silt bed associated with the final drainage of Lake Ojibway. Varve thickness measurements allow the correlation of these sections with the main Ojibway varve record that spans ∼2129 years in the region (where varve 1 represents the start of sedimentation). The Matagami sequence covers varve years 1644–1874 and the onset of the Cochrane readvance occurred in varve year 1817. The lower part of the La Reine sequence below the bottom chaotic rhythmites was deposited between varve years 1843–1877, while the overlying set of thick varves is correlated to varve years 2065–2129, thus indicating a hiatus of 188 varves. The distinct thick varves show strong compositional and stratigraphic similarities with the Connaught sequence reported elsewhere in the basin and point to a connection with the late-glacial (Cochrane) ice dynamics, which appear to have played an important role on the lake evolution. These results indicate that the late-stage history of Lake Ojibway was marked by the already known Cochrane major ice readvance which was followed by two drainage events separated by at least 65 years, consistent with North Atlantic sediment records that document a two-step drainage of Lake Agassiz-Ojibway.

This paper examines how services trade and policies contribute to connectivity. It highlights the economic relevance of services and identifies some key channels through which trade in services contributes to physical and digital connectivity. The paper examines the impact of services trade policies on connectivity in view of recent research showing their impact on sectoral performance, economic welfare and development. Finally, it discusses the positive contribution that aid for trade can make in support of services policies. The paper finds that services sectors play a multifaceted and significant role in connecting countries to the international trading system, and matter greatly to economic development and the achievement of the Sustainable Development Goals (SDGs). Services significantly affect connectivity by: (i) providing the basic infrastructure to support trade in goods; (ii) facilitating supply chains and entering trade as value added embodied in goods; (iii) providing the backbone that enables e-commerce and the on-line supply of services; (iv) and enhancing export diversification through their cross-border electronic supply. The paper underscores that services trade policies have a fundamental impact on connectivity. Restrictions to investment and cross-border trade in services remain high and widespread. But an enabling policy environment – promoting competition, openness to trade and investment, and adequate regulatory frameworks – can enhance connectivity, lower trade costs, and foster growth and economic performance. For example, improving the policy environment for services sectors can help attract the FDI required to meet the SDGs and develop the ICT infrastructure needed to bridge the digital divide. Aid for Trade can play a supportive role in this regard.

Time perception (TP) impairment in schizophrenia has been originally described by clinicians and afterwards addressed in laboratory. Previous studies generally observed that schizophrenia patients overestimate time and that their timing sensitivity is impaired. However, because of the disease cognitive impairments, no study until now allows to draw definitive conclusions about the nature of TP disturbances. The aim of this study is to isolate a genuine TP disorder in schizophrenia, i.e., a disorder that would be related to the functioning of an internal clock. The main hypothesis tested is that patients' internal clock runs faster than that of healthy controls. Twenty-five patients suffering from a first-episode of schizophrenia and twenty-five healthy controls performed an innovative task called method of dynamic stimuli , designed to measure the natural frequency ( F n ) of the internal clock, concomitant with a neuropsychological assessment. We observed no significant difference in F n between groups. Compared to controls, there was a marginally higher variability in time reproduction in patients. Patients' pattern of results and significant correlations between TP tasks and memory outcomes suggest that TP impairments are related to memory impairment in schizophrenia. These conclusions are supported by a growing literature showing that cognition is involved in TP in schizophrenia.

Paleoecological investigations of organic-rich sediments and radiometric dating of fossil wood fragments were undertaken to constrain the age of an extensive pre-Holocene nonglacial sediment sequence exposed along the Nottaway River in the southeastern sector of the Hudson Bay Lowlands, a key region for the study of the dynamics of the Laurentide ice sheet (LIS). Pollen and macrofossil analyses indicate that these sediments were deposited under climate conditions similar to those of today, whereas radiocarbon dating of a wood log yielded an age beyond the effective limit of this method. U and Th isotopic analysis on 9 fossil and 1 modern wood samples showed that the fossil wood fragments were subject to a significant episode of U uptake during burial. Despite mechanical cleaning of the wood outer surfaces, non-authigenic 230 Th was found in most wood samples. Correction for this detrital contamination was made using 232 Th as an index and assuming typical crustal Th/U ratio. Plotting of the data within a 3-D isochron indicates that the presence of non-authigenic 230 Th is not the only factor affecting the U–Th system, thereby showing evidence for a complex pattern of U uptake and/or intermittent open system behavior. This U mobility, however, appears to have been limited, as indicated by the relatively narrow range of corrected 230 Th/U ages and the cluster of U–Th data between the 100–120 ka isochrons in the U-series evolution diagram. Taken together, our paleoecological and U–Th results tend to suggest that the apparent calculated corrected 230 Th/U ages may be considered as a reliable geochronological constraint that assigns the Nottaway River sediments to the end of the last interglacial (marine isotopic stage 5e). The high degree of compaction of the fine-grained deposits enclosing the fossil wood appear to be one of the main factor that limited hydraulic gradients and associated isotopic fluxes through the unit. The stratigraphic context indicates that the overconsolidated nature of the wood-bearing deposit is associated with ice advance in the region. Accordingly, the minimum age limit provided by the corrected 230 Th/U ages (i.e., ∼100 ka) may also be interpreted as a coarse constraint on the timing and extent of the eastern sector of the LIS at the onset of the last glacial cycle.

Deglaciation of the James Bay region was highly dynamic, with the occurrence of ice (Cochrane) readvances into glacial Lake Ojibway around final deglaciation time, which culminated with the drainage of Ojibway waters into Hudson Bay and subsequent incursion of the Tyrrell Sea at ∼8 ka. Renewed interest on these events comes from the possible link between the drainage of the ice-dammed Lake Agassiz-Ojibway and a major climate deterioration known as the 8.2-ka cooling event. Recent glaciological modeling suggests that this drainage may have occurred subglacially, a mechanism that can accommodate more than one lake discharge, as suggested by marine records. The exact number and timing of drainage events, as well as location of the lake discharge pathway(s) remain, however, largely unconstrained. Here we focus on the events that led to the drainage of Lake Ojibway by documenting late-glacial sedimentary sequences located east of James Bay. Our investigations indicate that the deglacial sequence consists of a readvance till, extensive Ojibway rhythmites, and thick marine sediments. The glaciolacustrine and marine units are separated by a 60 cm-thick horizon composed of laminated silt beds containing rounded clay balls and disseminated clasts resulting from the abrupt drainage of the lake. Radiocarbon dating of marine fossils lying above the drainage horizon indicates that the glaciolacustrine episode ended around 8128–8282 cal yr BP. Micropaleontological analyses reveal that freshwater ostracods ( Candona sp.) and marine microfossils (foraminifers, dinocysts) occur together in the upper part of the Ojibway sediments. Analysis of oxygen isotopes (δ 18 O) of ostracods and foraminifers originating from the same stratigraphic position show highly contrasting values that suggest possible subglacial exchanges between Lake Ojibway and Tyrrell Sea waters prior to the final drainage event. The complexity of the deglacial events is further indicated by radiocarbon dating of marine shells retrieved from a Cochrane till that suggests that the last ice readvance occurred almost simultaneously with the final lake discharge. These results bring additional constraints on the drainage mechanism of the coalesced Lake Agassiz-Ojibway and indicate that the James Bay region formed an important drainage pathway for meltwaters at the end of the last deglaciation.

Provenance studies of anomalously high-flux layers of ice-rafted detritus (IRD) in North Atlantic sedi- ments of the last glacial cycle show evidence for massive iceberg discharges coming from the Hudson Strait region of the Laurentide Ice Sheet (LIS). Although these so-called Heinrich events (H events) are commonly thought to be associated with abrupt drawdown of the LIS interior, uncertainties remain regarding the sector(s) of this multi-domed ice sheet that conveyed ice through Hudson Strait. In Northern Quebec and Labrador (NQL), large-scale patterns of glacial lineations indicate massive ice flows towards Ungava Bay and Hudson Strait that could reflect the participation of the Labrador-Quebec ice dome in H events. Here we evaluate this hypothesis by constraining the source of NQL glacial deposits, which provide an estimate of the provenance characteristics of IRD originating from this sector. Specifically, we use 40 Ar/ 39 Ar ages of detrital hornblende grains in 25 till samples distributed along a latitudinal transect (lat. 58 ! ) extending east and west of Ungava Bay. The data show that tills located west and southwest of the Ungava Bay region are largely dominated by hornblende grains with Archean ages (>2.6 Ga), while tills located east of Ungava Bay are characterized by grains with early Paleo- proterozoic ages (2.0-1.8 Ga), although most samples contain a few Archean-age grains. IRD derived from the NQL region should thus be characterized by a large proportion of Archean-age detrital grains, which contrasts significantly with the predominant Paleoproterozoic 40 Ar/ 39 Ar ages (1.8-1.6 Ga) typically reported for the dominant age population of hornblende grains in H layers. Comparisons with IRD through the last glacial cycle from a western North Atlantic core off Newfoundland do not show evidence for any prominent ice-rafted event with the provenance characteristics of NQL glacial deposits, thereby suggesting that significant ice-calving event(s) from the Labrador-Quebec sector may have been limited throughout that interval. Although these results tend to point towards a relative stability of this ice dome during H events, our study also indicates that further provenance work is required on IRD proximal to the Hudson Strait mouth in order to constrain with a greater confidence the sector(s) of the LIS that fed ice into Hudson Strait during H events. Alternatively, these results and other paleogeographic considerations tend to support models suggesting that part of the Ungava Bay glacial lineations could be associated with a Late-Glacial ice flow across Hudson Strait.

Resume De tous les modeles neurocognitifs de la schizophrenie, le modele de C.D. Frith est l’un de ceux qui a recu le plus d’attention, notamment parce qu’il offre un cadre permettant de lier les diverses manifestations de la maladie aux perturbations cognitives et a la neurobiologie sous-jacente. Ce modele repose sur le postulat de l’existence de deux composantes, le self-monitoring et le monitoring. La premiere composante permet, a l’aide des metarepresentations, de rester conscient de ses propres buts et intentions. La seconde composante du modele renvoie a ce qui est communement appele la « theorie de l’esprit » et concerne le monitoring des connaissances et intentions d’autrui. Le present article vise a en examiner sa validite. Apres avoir passe en revue les bases empiriques et theoriques du modele de Frith, les points forts et faibles du modele sont mis en relief, notamment en comparaison avec les propositions theoriques de Hardy-Bayle et d’Abu-Akel. Les differentes critiques du modele sont ensuite examinees, en particulier celles des tenants de la phenomenologie, qui mettent en garde contre la vision reductionniste inherente a certains presupposes du modele. A ce sujet, les critiques de Gallagher sont particulierement percutantes en ce qu’elles remettent en question les fondements du modele. La validite du modele de Frith est finalement discutee dans son ensemble a la lueur de ces critiques et des modeles concurrents et il se degage, en guise de conclusion, que la portion self-monitoring du modele necessite d’etre redefinie alors que l’evaluation de la « theorie de l’esprit » devrait etre davantage standardisee.

The emergence of low-frequency, high-amplitude, quasi-periodic (∼100-kyr) glacial variability during the middle Pleistocene in the absence of any significant change in orbital forcing indicates a fundamental change internal to the climate system. This middle Pleistocene transition (MPT) began 1250 ka and was complete by 700 ka. Its onset was accompanied by decreases in sea surface temperatures (SSTs) in the North Atlantic and tropical-ocean upwelling regions and by an increase in African and Asian aridity and monsoonal intensity. During the MPT, long-term average ice volume gradually increased by ∼50 m sea-level equivalent, whereas low-frequency ice-volume variability experienced a 100-kyr lull centered on 1000 ka followed by its reappearance ∼900 ka, although as a broad band of power rather than a narrow, persistent 100-kyr cycle. Additional changes at 900 ka indicate this to be an important time during the MPT, beginning with an 80-kyr event of extreme SST cooling followed by the partial recovery and subsequent stabilization of long-term North Atlantic and tropical ocean SSTs, increasing Southern Ocean SST variability primarily associated with warmer interglacials, the loss of permanent subpolar sea-ice cover, and the emergence of low-frequency variability in Pacific SSTs and global deep-ocean circulation. Since 900 ka, ice sheets have been the only component of the climate system to exhibit consistent low-frequency variability. With the exception of a near-universal organization of low-frequency power associated with marine isotope stages 11 and 12, all other components show an inconsistent distribution of power in frequency-time space, suggesting a highly nonlinear system response to orbital and ice-sheet forcing. Most hypotheses for the origin of the MPT invoke a response to a long-term cooling, possibly induced by decreasing atmospheric pCO2. None of these hypotheses, however, accounts for the geological constraint that the earliest Northern Hemisphere ice sheets covered a similar or larger area than those that followed the MPT. Given that the MPT was associated with an increase in ice volume, this constraint requires that post-MPT ice sheets were substantially thicker than pre-MPT ice sheets, indicating a change in subglacial conditions that influence ice dynamics. We review evidence in support of the hypothesis that such an increase in ice thickness occurred as crystalline Precambrian Shield bedrock became exposed by glacial erosion of a thick mantle of regolith. This exposure of a high-friction substrate caused thicker ice sheets, with an attendant change in their response to the orbital forcing. Marine carbon isotope data indicate a rapid transfer of organic carbon to inorganic carbon in the ocean system during the MPT. If this carbon came from terrigenous sources, an increase in atmospheric pCO2 would be likely, which is inconsistent with evidence for widespread cooling, Apparently rapid carbon transfer from terrestrial sources is difficult to reconcile with gradual erosion of regolith. A more likely source of organic carbon and nutrients (which would mitigate pCO2 rise) is from shelf and upper slope marine sediments, which were fully exposed for the first time in millions of years in response to thickening ice sheets and falling sealevels during the MPT. Modeling indicates that regolith erosion and resulting exposure of crystalline bedrock would cause an increase in long-term silicate weathering rates, in good agreement with marine Sr and Os isotopic records. We use a carbon cycle model to show that a post-MPT increase in silicate weathering rates would lower atmospheric pCO2 by 7–12 ppm, suggesting that the attendant cooling may have been an important feedback in causing the MPT.

The transition from 41- to 100-kyr glacial cycles and concomitant increase in global ice volume ~1 Ma remain an enigmatic feature of late Cenozoic climate. Here, we examine the petrology, mineralogy, and geochemistry of the silicate fraction of tills spanning the past 2 Ma from the north-central United States to evaluate the hypothesis that this so-called middle Pleistocene transition (MPT) occurred by erosion of regolith and subsequent exposure of underlying Canadian Shield bedrock by the Laurentide ice sheet. These data indicate that late Pliocene tills are depleted in crystalline lithologies, unstable minerals, and major-element oxides derived from plagioclase and ferromagnesians and are enriched in kaolinite, quartz, iron oxides, TiO2bearing resistates, and meteoric 10 Be. In contrast, early and middle Pleistocene tills show enrichment in crystalline lithologies, stable minerals, and major oxides derived from plagioclase and ferromagnesians and depletion in meteoric 10 Be, whereas late Pleistocene tills show major-element concentrations that are most similar to that of fresh shield bedrock. Marine isotope records of Sr, Os, and Hf show significant changes around the MPT that are consistent with the removal of a regolith and the exhumation of fresh silicate bedrock. These results indicate that ice sheets initially expanded on highly weathered bedrock and progressively exhumed a fresher rock source, thereby supporting the hypothesis that a change in the composition of the substrate underlying ice sheets best explains the origin of the MPT. D 2004 Elsevier B.V. All rights reserved.

We argue that competitive diffusion is a driver of the trend toward international investment agreements (IIAs) with stricter investment rules, namely defensive moves of developing countries concerned about foreign direct investment (FDI) diversion in favor of competing host countries. Accounting for spatial dependence in the formation of bilateral investment treaties (BITs) and preferential trade agreements (PTAs) that contain investment provisions, we find that the increase in agreements with stricter provisions on investor-state dispute settlement and pre-establishment national treatment is a contagious process. Specifically, a developing country is more likely to sign an agreement with weak investment provisions if other developing countries that compete for FDI from the same developed country have previously signed agreements with similarly weak provisions. Conversely, contagion in agreements with strong provisions exclusively derives from agreements with strong provisions that other FDI-competing developing countries have previously signed with a specific developed source country of FDI.

We focus on investor-state dispute settlement provisions contained in various, though far from all, bilateral investment treaties as a possible determinant of BIT-related effects on bilateral FDI flows. Our estimation results prove to be sensitive to the specification of these provisions as well as the inclusion of transition countries in the sample. Stricter dispute settlement provisions do not necessarily result in higher FDI inflows so that the effectiveness of BITs as a credible commitment device remains elusive.

Outcrops bearing stained, striated facets indicative of north–northeastward moving ice, truncated by unstained, striated facets indicative of various younger flows occur in the Caniapiscau area of north–central Quebec. This is the first report of differential staining of striated facets in the region. We propose that the staining occurred in an ice-free interval of probable interglacial age. This early ice flow probably occurred during ice retreat toward the Quebec highlands. Ice flow and glacial transport data from the southern Hudson Bay and James Bay basins indicate that the next major regional ice flow was toward the northwest and resulted from the expansion of an Early Wisconsinan glacier in the Quebec highlands. The northern part of this flow was diverted northwestward through Hudson Bay, and the southern part southwestward across James Bay, following a progressive counterclockwise rotation of flow. A zone of intersection (ZI) of two major glacier bedform systems, often referred to as the horseshoe-shaped Labrador Ice Divide, represents the head of a large northward convergent ice-flow system that extended to Ungava Bay and beyond. The Ungava flow propagated southward and captured the head of the opposing flow from an outflow centre located east of Caniaspiscau reservoir. We propose that this capture event correlates with the Gold Cove Advance in Ungava Bay and on Baffin Island at about 9900 14C yr BP. It is the largest advance of Quebec-Labrador ice yet proposed for the region. This correlation is based on the relative ice-flow chronology, accommodation of glacial lakes Naskaupi and McLean in the deglaciation sequence, the constraints placed on Last Glacial Maximum (LGM) ice configuration by the postglacial uplift pattern and events in the deep-sea record. Therefore, the Ungava ice-flow pattern is not a relict pre-Wisconsinan glacial landscape as recently proposed.