Direct linking of Greenland and Antarctic ice cores at the Toba eruption (74 ka BP)

The Toba eruption that occurred some 74 ka ago in Sumatra, Indonesia, is among the largest volcanic events on Earth over the last 2 million years. Tephra from this eruption has been spread over vast areas in Asia, where it constitutes a major time marker close to the Marine Isotope Stage 4/5 boundary. As yet, no tephra associated with Toba has been identified in Greenland or Antarctic ice cores. Based on new accurate dating of Toba tephra and on accurately dated European stalagmites, the Toba event is known to occur between the onsets of Greenland interstadials (GI) 19 and 20. Furthermore, the existing linking of Greenland and Antarctic ice cores by gas records and by the bipolar seesaw hypothesis suggests that the Antarctic counterpart is situated between Antarctic Isotope Maxima (AIM) 19 and 20. In this work we suggest a direct synchronization of Greenland (NGRIP) and Antarctic (EDML) ice cores at the Toba eruption based on matching of a pattern of bipolar volcanic spikes. Annual layer counting between volcanic spikes in both cores allows for a unique match. We first demonstrate this bipolar matching technique at the already synchronized Laschamp geomagnetic excursion (41 ka BP) before we apply it to the suggested Toba interval. The Toba synchronization pattern covers some 2000 yr in GI-20 and AIM-19/20 and includes nine acidity peaks that are recognized in both ice cores. The suggested bipolar Toba synchronization has decadal precision. It thus allows a determination of the exact phasing of inter-hemispheric climate in a time interval of poorly constrained ice core records, and it allows for a discussion of the climatic impact of the Toba eruption in a global perspective. The bipolar linking gives no support for a long-term global cooling caused by the Toba eruption as Antarctica experiences a major warming shortly after the event. Furthermore, our bipolar match provides a way to place palaeo-environmental records other than ice cores into a precise climatic context.

Quantitative summer and winter temperature reconstructions from pollen and chironomid data between 15 and 8 ka BP in the Baltic–Belarus area

New pollen based reconstructions of summer (May-to-August) and winter (December-to-February) temperatures between 15 and 8 ka BP along a S-N transect in the Baltic-Belarus (BB) area display trends in temporal and spatial changes in climate variability. These results are completed by two chironomid-based July mean temperature reconstructions. The magnitude of change compared with modern temperatures was more prominent in the northern part of BB area. The 4 C degrees winter and 2 C degrees summer warming at the start of GI-1 was delayed in the BB area and Lateglacial maximum temperatures were reached at ca 13.6 ka BP, being 4 C degrees colder than the modern mean. The Younger Dryas cooling in the area was 5 C degrees colder than present, as inferred by all proxies. In addition, our analyses show an early Holocene divergence in winter temperature trends with modern values reaching 1 ka earlier (10 ka BP) in southern BB compared to the northern part of the region (9 ka BP).

A first chironomid-based summer temperature reconstruction (13–5 ka BP) around 49°N in inland Europe compared with local lake development

Temperature reconstructions for the end of the Pleistocene and the first half of the Holocene based on biotic proxies are rare for inland Europe around 49°N. We analysed a 7 m long sequence of lake deposits in the Vihorlat Mts in eastern Slovakia (820 m a.s.l.). Chironomid head capsules were used to reconstruct mean July temperature (TJuly), other proxies (diatoms, green algae, pollen, geochemistry) were used to reconstruct local environmental changes that might have affected the climate reconstruction, such as epilimnetic total phosphorus concentrations (TP), lake level changes and development of surrounding vegetation. During the Younger Dryas (YD), temperature fluctuated between 7 and 11 °C, with distinct, decadal to centennial scale variations, that agree with other palaeoclimate records in Europe such as δ18O content in stalagmites or Greenland ice cores. The results indicate that the site was somewhat colder than expected from the general south-to-north YD temperature gradient within Europe, possibly because of north-facing exposition. The warmer phases of the YD were characterised by low water level or even complete desiccation of the lake (12,200-12,400 cal yr BP). At the Late-Glacial/Holocene transition TJuly steeply increased from from 11 to 15.5 °C (11,700-11,400 cal yr BP) - the highest TJuly for entire sequence. This rapid climate change was reflected by all proxies as a compositional change and increasing species diversity. The open woodlands of Pinus, Betula, Larix and Picea were replaced by broad-leaved temperate forests dominated by Betula, later by Ulmus and finally by Corylus (ca 9700 cal yr BP). At the same time, input of eroded coarse-grained material into the lake decreased and organic matter (LOI) and biogenic silica increased. The Early-Holocene climate was rather stable till 8700 cal yr BP, with temporary decrease in TJuly around 11,200 cal yr BP. The lake was productive with a well-developed littoral, as indicated by both diatoms and chironomids. A distinct decline of TJuly to 10 °C between 8700 and 8000 cal yr BP was associated with decreasing chironomid diversity and increasing climate moistening indicated by pollen. Tychoplanktonic and phosphorus-demanding diatoms increased which might be explained by hydrological and land-cover changes. Later, a gradual warming started after 7000 cal yr BP and representation of macrophytes, periphytic diatoms and littoral chironomids increased. Our results suggest that the Holocene thermal maximum was taking place unusually early in the Holocene at our study site, but its timing might be affected by topography and mesoclimate. We further demonstrated that temperature changes had coincided with variations in local hydrology

Prosthetic Rehabilitation, Implant Survival and Quality of Life 2 to 5 Years after Resection of Oral Tumors

Background: After oral tumor resection, structural and functional rehabilitation by means of dental prostheses is complex, and positive treatment outcome is not always predictable. Purpose: The objective of the study was to report on oral rehabilitation and quality of life 2-5 years after resection of malignant oral tumors. Materials and Methods: Data of 46 patients (57 ± 7 years) who underwent oral tumor surgery were available. More than 50% of tumors were classified T3 or T4. Open oro-nasal defects resulted in 12 patients and full mandibulary block resections in 23 patients. Comprehensive planning, implant placement, and prosthetic rehabilitation followed an interdisciplinary protocol. Analysis comprised tumor location, type of prostheses, implant survival, and quality of life. Results: Because of advanced tumor status, resections resulted in marked alteration of the oral anatomy requiring complex treatment procedures. Prosthetic rehabilitation comprised fixed and removable prostheses, with 104 implants placed in 28 patients (60%). Early implant loss was high (13%) and cumulative survival rate of loaded implants was <90% after 5 years. Prosthetic plans had to be modified because of side effects of tumor therapy, complications with implants and tumor recurrence. The majority of patients rated quality of life favorable, but some experienced impaired swallowing, dry mouth, limited mouth opening, appearance, and soreness. Conclusions: Some local effects of tumor therapy could not be significantly improved by prosthetic rehabilitation leading to functional and emotional disability. Many patients had passed away or felt too ill to fill the questionnaires. This case series confirms the complex anatomic alterations after tumor resection and the need for individual treatment approaches especially regarding prosthesis design. In spite of disease-related local and general restrictions, most patients gave a positive assessment of quality of life.

Facial esthetics in children with unilateral cleft lip and palate 3 years after alveolar bonegrafting combined with rhinoplasty between 2 and 4 years of age

OBJECTIVES To evaluate facial esthetics in patients with unilateral cleft lip and palate (UCLP) after alveolar bone grafting combined with rhinoplasty between 2 and 4 years of age. DESIGN Retrospective case-control study. SETTING The Department of Pediatric Surgery, Institute of Mother and Child, Warsaw, Poland. MATERIAL AND METHODS Photographs of full faces and cropped images of five nasolabial components: nasal deviation, nasal form, nasal profile, vermillion border, and inferior view were assessed by 5 professional and 14 layraters in 29 children (23 boys and 6 girls; mean age = 5.3 years, SD 0.5; Early-grafted group) and 30 children (20 boys and 10 girls; mean age = 5.5 years, SD 1.0; Non-grafted group) with complete unilateral cleft lip and palate repaired with a one-stage closure. The groups differed regarding the timing of alveolar bone grafting: in the Early-grafted group, alveolar bone grafting in combination with rhinoplasty (ABG-R) was performed between 2 and 4 years of age (mean age = 2.3 years; SD 0.6); in the Non-grafted group, the alveolar defect was grafted after 9 years of age. No primary nose correction was carried out in any group. To rate esthetics, a modified five-grade esthetic index of Asher-McDade was used, where grade 1 means the most esthetic and grade 5 - the least esthetic outcome. RESULTS Esthetics of full faces and of all nasolabial elements in the Early-grafted group was significantly better than in Non-grafted group. The scores in the Early-grafted group ranged from 2.30 to 2.66 points, whereas in the Non-grafted group ranged from 2.66 to 3.17 points. All intergroup differences were statistically significant (p < 0.05). CONCLUSIONS Three years post-operatively, early alveolar bone grafting combined with rhinoplasty is favorable for facial esthetics in children with UCLP, but a longer follow-up is needed to assess whether the improvement was permanent.

Optimal time for initiating antiretroviral therapy (ART) in HIV-infected, treatment-naive children aged 2 to 5 years old

BACKGROUND The use of combination antiretroviral therapy (cART) comprising three antiretroviral medications from at least two classes of drugs is the current standard treatment for HIV infection in adults and children. Current World Health Organization (WHO) guidelines for antiretroviral therapy recommend early treatment regardless of immunologic thresholds or the clinical condition for all infants (less than one years of age) and children under the age of two years. For children aged two to five years current WHO guidelines recommend (based on low quality evidence) that clinical and immunological thresholds be used to identify those who need to start cART (advanced clinical stage or CD4 counts ≤ 750 cells/mm(3) or per cent CD4 ≤ 25%). This Cochrane review will inform the current available evidence regarding the optimal time for treatment initiation in children aged two to five years with the goal of informing the revision of WHO 2013 recommendations on when to initiate cART in children. OBJECTIVES To assess the evidence for the optimal time to initiate cART in treatment-naive, HIV-infected children aged 2 to 5 years. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, the AEGIS conference database, specific relevant conferences, www.clinicaltrials.gov, the World Health Organization International Clinical Trials Registry platform and reference lists of articles. The date of the most recent search was 30 September 2012. SELECTION CRITERIA Randomised controlled trials (RCTs) that compared immediate with deferred initiation of cART, and prospective cohort studies which followed children from enrolment to start of cART and on cART. DATA COLLECTION AND ANALYSIS Two review authors considered studies for inclusion in the review, assessed the risk of bias, and extracted data on the primary outcome of death from all causes and several secondary outcomes, including incidence of CDC category C and B clinical events and per cent CD4 cells (CD4%) at study end. For RCTs we calculated relative risks (RR) or mean differences with 95% confidence intervals (95% CI). For cohort data, we extracted relative risks with 95% CI from adjusted analyses. We combined results from RCTs using a random effects model and examined statistical heterogeneity. MAIN RESULTS Two RCTs in HIV-positive children aged 1 to 12 years were identified. One trial was the pilot study for the larger second trial and both compared initiation of cART regardless of clinical-immunological conditions with deferred initiation until per cent CD4 dropped to <15%. The two trials were conducted in Thailand, and Thailand and Cambodia, respectively. Unpublished analyses of the 122 children enrolled at ages 2 to 5 years were included in this review. There was one death in the immediate cART group and no deaths in the deferred group (RR 2.9; 95% CI 0.12 to 68.9). In the subgroup analysis of children aged 24 to 59 months, there was one CDC C event in each group (RR 0.96; 95% CI 0.06 to 14.87) and 8 and 11 CDC B events in the immediate and deferred groups respectively (RR 0.95; 95% CI 0.24 to 3.73). In this subgroup, the mean difference in CD4 per cent at study end was 5.9% (95% CI 2.7 to 9.1). One cohort study from South Africa, which compared the effect of delaying cART for up to 60 days in 573 HIV-positive children starting tuberculosis treatment (median age 3.5 years), was also included. The adjusted hazard ratios for the effect on mortality of delaying ART for more than 60 days was 1.32 (95% CI 0.55 to 3.16). AUTHORS' CONCLUSIONS This systematic review shows that there is insufficient evidence from clinical trials in support of either early or CD4-guided initiation of ART in HIV-infected children aged 2 to 5 years. Programmatic issues such as the retention in care of children in ART programmes in resource-limited settings will need to be considered when formulating WHO 2013 recommendations.

A compilation of Western European terrestrial records 60–8 ka BP: towards an understanding of latitudinal climatic gradients

Terrestrial records of past climatic conditions, such as lake sediments and speleothems, provide data of great importance for understanding environmental changes. However, unlike marine and ice core records, terrestrial palaeodata are often not available in databases or in a format that is easily accessible to the non-specialist. As a consequence, many excellent terrestrial records are unknown to the broader palaeoclimate community and are not included in compilations, comparisons, or modelling exercises. Here we present a compilation of Western European terrestrial palaeo-records covering, entirely or partially, the 60–8-ka INTIMATE time period. The compilation contains 56 natural archives, including lake records, speleothems, ice cores, and terrestrial proxies in marine records. The compilation is limited to include records of high temporal resolution and/or records that provide climate proxies or quantitative reconstructions of environmental parameters, such as temperature or precipitation, and that are of relevance and interest to a broader community. We briefly review the different types of terrestrial archives, their respective proxies, their interpretation and their application for palaeoclimatic reconstructions. We also discuss the importance of independent chronologies and the issue of record synchronization. The aim of this exercise is to provide the wider palaeo-community with a consistent compilation of high-quality terrestrial records, to facilitate model-data comparisons, and to identify key areas of interest for future investigations. We use the compilation to investigate Western European latitudinal climate gradients during the deglacial period and, despite of poorly constrained chronologies for the older records, we summarize the main results obtained from NW and SW European terrestrial records before the LGM.

Sedimentary evolution and environmental history of Lake Van (Turkey) over the past 600,000 years

The lithostratigraphic framework of Lake Van, eastern Turkey, has been systematically analysed to document the sedimentary evolution and the environmental history of the lake during the past ca 600,000 years. The lithostratigraphy and chemostratigraphy of a 219 m long drill core from Lake Van serves to separate global climate oscillations from local factors caused by tectonic and volcanic activity. An age model was established based on the climatostratigraphic alignment of chemical and lithological signatures, validated by 40Ar/39Ar ages. The drilled sequence consists of ca 76% lacustrine carbonaceous clayey silt, ca 2% fluvial deposits, ca 17% volcaniclastic deposits and 5% gaps. Six lacustrine lithotypes were separated from the fluvial and event deposits, such as volcaniclastics (ca 300 layers) and graded beds (ca 375 layers), and their depositional environments are documented. These lithotypes are: (i) graded beds frequently intercalated with varved clayey silts reflect rising lake-levels during the terminations; (ii) varved clayey silts reflect strong seasonality and an intralake oxic–anoxic boundary, for example, lake-level highstands during interglacials/interstadials; (iii) CaCO3-rich banded sediments are representative of a lowering of the oxic-anoxic boundary, for example, lake-level decreases during glacial inceptions; (iv) CaCO3-poor banded and mottled clayey silts reflect an oxic–anoxic boundary close to the sediment-water interface, for example, lake-level low-stands during glacials/stadials; (v) diatomaceous muds were deposited during the early beginning of the lake as a fresh water system; and (vi) fluvial sands and gravels indicate the initial flooding of the lake basin. The recurrence of lithologies (i) to (iv) follows the past five glacial/interglacial cycles. A 20 m thick disturbed unit reflects an interval of major tectonic activity in Lake Van at ca 414 ka BP.

EDML1: a chronology for the EPICA deep ice core from Dronning Maud Land, Antarctica, over the last 150 000 years

A chronology called EDML1 has been developed for the EPICA ice core from Dronning Maud Land (EDML). EDML1 is closely interlinked with EDC3, the new chronology for the EPICA ice core from Dome-C (EDC) through a stratigraphic match between EDML and EDC that consists of 322 volcanic match points over the last 128 ka. The EDC3 chronology comprises a glaciological model at EDC, which is constrained and later selectively tuned using primary dating information from EDC as well as from EDML, the latter being transferred using the tight stratigraphic link between the two cores. Finally, EDML1 was built by exporting EDC3 to EDML. For ages younger than 41 ka BP the new synchronized time scale EDML1/EDC3 is based on dated volcanic events and on a match to the Greenlandic ice core chronology GICC05 via 10Be and methane. The internal consistency between EDML1 and EDC3 is estimated to be typically ~6 years and always less than 450 years over the last 128 ka (always less than 130 years over the last 60 ka), which reflects an unprecedented synchrony of time scales. EDML1 ends at 150 ka BP (2417 m depth) because the match between EDML and EDC becomes ambiguous further down. This hints at a complex ice flow history for the deepest 350 m of the EDML ice core.

Four thousand years of vegetation and fire history in the spruce forests of northern Kyrgyzstan (Kungey Alatau, Central Asia)

Analyses of pollen, macrofossils and microscopic charcoal in the sediment of a small sub-alpine lake (Karakol, Kyrgyzstan) provide new data to reconstruct the vegetation history of the Kungey Alatau spruce forest during the late-Holocene, i.e. the past 4,000 years. The pollen data suggest that Picea schrenkiana F. and M. was the dominant tree in this region from the beginning of the record. The pollen record of pronounced die-backs of the forests, along with lithostratigraphical evidence, points to possible climatic cooling (and/or drying) around 3,800 cal year B.P., and between 3,350 and 2,520 cal year B.P., with a culmination at 2,800-2,600 cal B.P., although stable climatic conditions are reported for this region for the past 3,000-4,000 years in previous studies. From 2,500 to 190 cal year B.P. high pollen values of P. schrenkiana suggest rather closed and dense forests under the environmental conditions of that time. A marked decline in spruce forests occurred with the onset of modern human activities in the region from 190 cal year B.P. These results show that the present forests are anthropogenically reduced and represent only about half of their potential natural extent. As P. schrenkiana is a species endemic to the western Tien Shan, it is most likely that its refugium was confined to this region. However, our palaeoecological record is too recent to address this hypothesis thoroughly.

Late Quaternary paleosols and their paleoenvironmental significance along the Andean piedmont, Eastern Bolivia

The Andean piedmont of eastern Bolivia is situated at the southern margin of Amazonia characterized by an overall humid climate regime with a marked contrast between the rainy and dry seasons. The nearby Subandean foothills deliver abundant sandy sediments to the piedmont, leading to a complex array of sediments and paleosol horizons. Within this setting, the presented study analyzes four profiles of paleosol-sediment-sequences along incised ephemeral streams near Santa Cruz de la Sierra with a focus on past pedogenic variability in the context of the regional late Quaternary geomorphic and environmental evolution. Based on field observations, micromorphological analysis, geochemical and clay mineralogical data five classes of paleosol horizons could be distinguished. The individual paleosol horizons as well as the sediments, in which they developed, were interpreted regarding their paleoenvironmental significance, taking into consideration the various controls on soil formation with particular focus on changes of local environmental conditions through time. Thus, three different pathways of soil formation were established. On the late Quaternary timescale, the results suggest a strong relation between paleoenvironmental conditions (climate, vegetation etc.), soil environment (soil water flow, micro-environment) and the type of paleosol horizons developed in the study area. The formation of “red beds” (Bw horizons) implies very dry soil environments under dominantly dry conditions, which seem to have prevailed in the study area some time before ∼ 18 cal ka BP. Moderately dry but markedly seasonal environmental conditions with a long dry season and strong seasonal contrasts in soil water flow could explain the formation of moderately developed Bwt horizons around ∼ 18 cal ka BP and much of the mid-Holocene. The formation of Bt horizons and/or clay lamellae in relation to intense neoformation of clay and dominant clay illuviation by soil water points to wet conditions similar to today, which have probably prevailed in the study area before ∼ 8 cal ka BP and since ∼ 5 cal ka BP.

Persistence of Artemisia steppe in the Tangra Yumco Basin, west-central Tibet, China: despite or in consequence of Holocene lake-level changes?

The closed Tangra Yumco Basin underwent the strongest Quaternary lake-level changes so far recorded on the Tibetan Plateau. It was hitherto unknown what effect this had on local Holocene vegetation development. A 3.6-m sediment core from a recessional lake terrace at 4,700 m a.s.l., 160 m above the present lake level of Tangra Yumco, was studied to reconstruct Holocene flooding phases (sedimentology and ostracod analyses), vegetation dynamics and human influence (palynology, charcoal and coprophilous fungi analyses). Peat at the base of the profile proves lake level was below 4,700 m a.s.l. during the Pleistocene/Holocene transition. A deep-lake phase started after 11 cal ka BP, but the ostracod record indicates the level was not higher than similar to 4,720 m a.s.l. (180 m above present) and decreased gradually after the early Holocene maximum. Additional sediment ages from the basin suggest recession of Tangra Yumco from the coring site after 2.6 cal ka BP, with a shallow local lake persisting at the site until similar to 1 cal ka BP. The final peat formation indicates drier conditions thereafter. Persistence of Artemisia steppe during the Holocene lake high-stand resembles palynological records from west Tibet that indicate early Holocene aridity, in spite of high lake levels that may have resulted from meltwater input. Yet pollen assemblages indicate humidity closer to that of present potential forest areas near Lhasa, with 500-600 mm annual precipitation. Thus, the early mid-Holocene humidity was sufficient to sustain at least juniper forest, but Artemisia dominance persisted as a consequence of a combination of environmental disturbances such as (1) strong early Holocene climate fluctuations, (2) inundation of habitats suitable for forest, (3) extensive water surfaces that served as barriers to terrestrial diaspore transport from refuge areas, (4) strong erosion that denuded the non-flooded upper slopes and (5) increasing human influence since the late glacial.