Produção de hidrogênio por fermentação por um novo isolado de Clostridium beijerinckii

O hidrogênio (H2) tem sido considerado uma fonte de energia limpa bastante promissora, pois sua combustão origina apenas moléculas de água, sendo uma alternativa ao uso de combustíveis fósseis. Entretanto, os métodos atuais de produção de H2 demandam matérias-primas finitas e uma grande quantidade de energia, tornando a sua obtenção não sustentável. Mais recentemente, a via fermentativa tem sido considerada para a produção de H2, utilizando como matérias-primas efluentes industriais, materiais lignocelulósicos e biomassa de algas, denominado de bio-hidrogênio de primeira, segunda e terceira geração, respectivamente. Neste trabalho foi isolada uma bactéria anaeróbia a partir de uma cultura mista (lodo) de um sistema de tratamento de vinhaça, após pré-tratamento do lodo a pH 3 por 12 horas. Este microrganismo foi identificado com 99% de similaridade como Clostridium beijerinckii com base na sequência do gene RNAr 16S denominado de C. beijerinckii Br21. A temperatura e o pH mais adequados para o crescimento e produção de H2 por esta cultura foi 35 °C e pH inicial 7,0. A bactéria possui a capacidade de utilizar ampla variedade de fontes de carbono para a produção de H2 por fermentação, especialmente, monossacarídeos resultantes da hidrólise de biomassa de algas, tais como glicose, galactose e manose. Foram realizados ensaios em batelada para a produção de H2 com a bactéria isolada empregando diferentes concentrações de glicose e galactose, visando a sua futura utilização em hidrolisados de alga. Os parâmetros cinéticos dos ensaios de fermentação estimados pelo modelo de Gompertz modificado, como a velocidade máxima de produção (Rm), a quantidade máxima de hidrogênio produzido (Hmáx) e o tempo necessário para o início da produção de hidrogênio (fase lag) para a glicose (15 g/L) foram de: 58,27 mL de H2/h, 57,68 mmol de H2 e 8,29 h, respectivamente. Para a galactose (15 g/L), a Rm, Hmáx e foram de 67,64 mL de H2/h, 47,61 mmol de H2 e 17,22 horas, respectivamente. O principal metabólito detectado ao final dos ensaios de fermentação, foi o ácido butírico, seguido pelo ácido acético e o etanol, tanto para os ensaios com glicose, como com galactose. C. beijerinckii é um candidato bastante promissor para a produção de H2 por fermentação a partir de glicose e galactose e, consequentemente, a partir de biomassa de algas como substratos.

O nexo causal entre crédito rural e crescimento do produto agropecuário na economia brasileira

O nexo causal entre desenvolvimento financeiro e crescimento econômico vem ganhando destaque na literatura desde o início dos anos 1990. As principais linhas teóricas nessa área buscam demonstrar qual a significância da relação e o sentido da causalidade, se houver. Causalidade unidirecional no sentido do desenvolvimento financeiro para o crescimento econômico, bicausalidade entre ambos, e causalidade reversa, no sentido do crescimento para o desenvolvimento financeiro, são as principais hipóteses testadas nas pesquisas empíricas. O presente trabalho de tese tem por objetivo avaliar o nexo causal entre crédito (como um indicador do desenvolvimento financeiro) e crescimento no setor agropecuário brasileiro. O crédito rural como proporção do PIB agropecuário cresceu substancialmente desde meados da década de 90, passando de 15,44% em 1996 para 65,24% em 2014. Ao longo do período 1969-2014, a razão média anual entre crédito rural e PIB agropecuário foi de 43,87%. No mesmo período, o produto agropecuário cresceu em média 3,76% ao ano. Questiona-se se no mercado rural o crédito causa o crescimento agropecuário, se ocorre causalidade reversa ou se se opera a hipótese de bicausalidade. Para avaliar o nexo causal entre essas duas variáveis econômica foram empregados quatro procedimentos metodológicos: teste de causalidade de Granger em uma representação VAR com a abordagem de Toda e Yamamoto, teste de causalidade de Granger em um modelo FMOLS (Fully Modified OLS), teste de causalidade de Granger em um modelo ARDL (Autoregressive-Distributed Lag) e teste de causalidade de Granger no domínio da frequência, com o uso do método de Breitung e Candelon. Os resultados mostram de forma uniforme a presença de causalidade unidirecional do crédito rural para o crescimento do produto agropecuário. Causalidade reversa, no sentido do crescimento agropecuário para o crédito rural, não foi detectada de forma significativa em nenhum dos quatro métodos empregados. A não detecção de bicausalidade pode ser uma evidência do impacto da forte política de subsídio governamental ao crédito rural. A decisão do Governo quanto ao montante anual de crédito rural disponível a taxas de juros subsidiadas pode estar impedindo que o desempenho do setor, medido pela sua taxa de crescimento, exerça uma influência significativa na dinâmica do crédito rural. Os resultados também abrem a possibilidade a testar a hipótese de exogeneidade do crédito rural, o que seria uma extensão direta dos resultados obtidos.

Pistas fósiles asociadas a la discontinuidad fini-Messiniense en el margen norte de la Cuenca del Bajo Segura (SE España)

A detailed analysis of the Upper Messinian-Lower Pliocene at the northern border of the Bajo Segura Basin (BSB) has been carried out. Trace fossils of firm- and rockground were collected, aiding in the recognition of three ichnofacies: Glossifungites (types A and B), Entobia and Gnathichnus. The ichnological data provide evidence that the Pliocene flooding of the BSB, after the Messinian Salinity Crisis, was developed in two pulses. In the first one, the ingression penetrated only along the paleovalleys and produced a coastal trasgressive lag (P0). In the second one, the ingression overflowed the margins of the paleovalleys and extended throughout the entire northern margin, also producing a coastal transgressive lag in the base of the P2 system. The record of the Entobia and Gnathichnus ichnofacies in the clasts of both lags evidences a relatively fast deepening-upward trend in both the transgressions.

Extending working life in Finland. CEPS Working Document No. 387, 22 November 2013

This report reviews national and private initiatives to allow the elderly to continue their participation in the Finnish labour market and provides an analysis of the labour market and living conditions of seniors. We are interested in how those over 50 can be engaged in various forms of employment and lifelong learning. We find strong evidence that Finland generally provides good institutional conditions for active ageing. The quick and early ageing process was tackled by the fundamental pension reform that already prolonged retirement substantially and will probably facilitate later retirement as the attitudes concerning retirement change. On the other hand, Finland still seems to lag behind the other Nordic welfare states, has considerable problems in providing the same health conditions to low educated people in physically demanding occupations and could - – with respect to family pension in particular – invest further efforts in reforming the pension system. While many of the reforms Finland has conducted seem to be favourable and transferable to other European countries that still face the steepest phases of ageing in their societies, a reluctance towards changing attitudes that we observe in Finland, shows that organizing active ageing is a long-term project.

A Spatial Analysis of Agricultural Land Prices in Bavaria. Factor Markets Working Document No. 50, June 2013

This paper empirically analyses a dataset of more than 7,300 agricultural land sales transactions from 2001 and 2007 to identify the factors influencing agricultural land prices in Bavaria. We use a general spatial model, which combines a spatial lag and a spatial error model, and in addition account for endogeneity introduced by the spatially lagged dependent variable as well as other explanatory variables. Our findings confirm the strong influence of agricultural factors such as land productivity, of variables describing the regional land market structure, and of non-agricultural factors such as urban pressure on agricultural land prices. Moreover, the involvement of public authorities as a seller or buyer increases sales prices in Bavaria. We find a significant capitalisation of government support payments into agricultural land, where a decrease of direct payments by 1% would decrease land prices in 2007 and 2001 by 0.27% and 0.06%, respectively. In addition, we confirm strong spatial relationships in our dataset. Neglecting this leads to biased estimates, especially if aggregated data is used. We find that the price of a specific plot increases by 0.24% when sales prices in surrounding areas increase by 1%.

The effect of extreme cold temperatures on the risk of death in the two major Portuguese cities

It is well known that meteorological conditions influence the comfort and human health. Southern European countries, including Portugal, show the highest mortality rates during winter, but the effects of extreme cold temperatures in Portugal have never been estimated. The objective of this study was the estimation of the effect of extreme cold temperatures on the risk of death in Lisbon and Oporto, aiming the production of scientific evidence for the development of a real-time health warning system. Poisson regression models combined with distributed lag non-linear models were applied to assess the exposure-response relation and lag patterns of the association between minimum temperature and all-causes mortality and between minimum temperature and circulatory and respiratory system diseases mortality from 1992 to 2012, stratified by age, for the period from November to March. The analysis was adjusted for over dispersion and population size, for the confounding effect of influenza epidemics and controlled for long-term trend, seasonality and day of the week. Results showed that the effect of cold temperatures in mortality was not immediate, presenting a 1–2-day delay, reaching maximumincreased risk of death after 6–7 days and lasting up to 20–28 days. The overall effect was generally higher and more persistent in Lisbon than in Oporto, particularly for circulatory and respiratory mortality and for the elderly. Exposure to cold temperatures is an important public health problem for a relevant part of the Portuguese population, in particular in Lisbon.

(Appendix) Oxygen isotope record and carbonate mineralogy of the top part of ODP Hole 101-633A

Hole 633A was drilled in the southern part of Exuma Sound on the toe-of-slope of the southeastern part of Great Bahama Bank during ODP Leg 101. The top 55 m, collected as a suite of six approximately 9.5-m-long hydraulic piston cores, represents a Pliocene-Pleistocene sequence of periplatform carbonate ooze, a mixture of pelagic calcite (foraminifer and coccolith tests), some pelagic aragonite (pteropod tests), and bank-derived fine aragonite and magnesian calcite. A 1.6-m.y.-long hiatus was identified at 43.75 mbsf using calcareous nannofossil biostratigraphy and magnetostratigraphy. The 43.75-m-thick periplatform sequence above the hiatus is a complete late Pliocene-Quaternary record of the past 2.15 m.y. The d18O curve, primarily based on Globigerinoides sacculifera, clearly displays high-frequency/low-amplitude cycles during the early Pleistocene and low-frequency/high-amplitude cycles during the middle and late Pleistocene. Variations in aragonite content in the fine fraction of the periplatform ooze show a cyclic pattern throughout the Pleistocene, as previously observed in piston cores of the upper Pleistocene. These variations correlate well with the d18O record: high aragonite corresponds to light interglacial d18O values, and vice versa. Comparison of the d18O record and the aragonite curve helps to identify 23 interglacial and glacial oxygen-isotope stages, corresponding to 10.5 aragonite cycles (labeled A to K) commonly established during the middle and late Pleistocene (0.9 Ma-present). Strictly based on the aragonite curve, another 11 aragonite cycles, labeled L to V, were identified for the early Pleistocene (0.9 to 1.6 Ma). Mismatches between the d18O record and the aragonite curve occur mainly at some of the glacial-to-interglacial transitions, where aragonite increases usually lag behind d18O depletion. When one visually connects the minima on the Pleistocene aragonite curve, low-frequency (0.4 to 0.5 m.y.) supercycles seem to be superimposed on the high-frequency cycles. The timing of this supercycle roughly matches the timing of the Pleistocene carbonate preservation supercycles described in the Pacific, Indian, and Atlantic oceans. Mismatches between aragonite and d18O cycles are even more obvious for the late Pliocene (1.6 to 2.15 Ma). Irregular aragonite variations are observed for the late Pliocene, although after the onset of late Pleistocene-like glaciations in the North Atlantic Ocean 2.4 m.y. ago the d18O record has shown a mode of high-frequency/low-amplitude cycles. Initiation of climatically induced aragonite cycles occurs only at the Pliocene-Pleistocene transition, 1.6 m.y. ago. After that time, aragonite cycles are fully developed throughout the Quaternary. The 11-m-thick periplatform sequence below the hiatus represents a lower Pliocene interval between 3.75 and 4.45 Ma. The bottom half (4.25-4.45 Ma) has a fairly constant, high aragonite content (averaging 60%) and high sedimentation rates (28 m/m.y.) and corresponds to the end of the prolonged early Pliocene interglacial interval (4.1-5.0 Ma), established as a worldwide high sea-level stand. The second half (3.75-4.25 Ma), in which aragonite content decreases by successive steps, paralleled by a gradual 5180 enrichment in Globigerinoides sacculifera and low sedimentation rates (10 m/m.y), corresponds to the climatic deterioration established worldwide between 4.1 and 3.8 Ma, to a decrease of carbonate preservation observed in the equatorial Pacific Ocean, and to a global sea-level decline. Dolomite, a ubiquitous secondary component in the lower Pliocene, is interpreted as being authigenic and possibly related to diagenetic transformation of primary bank-derived fine magnesian calcite. Transformation of the primary mineralogical composition of the periplatform ooze was evidently minor, as the sediments have retained a detailed record of the Pliocene-Pleistocene climatic evolution. Clear evidence of diagenetic transformations in the periplatform ooze includes (1) the disappearance of magnesian calcite in the upper 20 m of Hole 633A, (2) the occurrence of calcite overgrowths on foraminiferal tests and microclasts at intermittent chalky core levels, and (3) the ubiquitous presence of authigenic dolomite in the lower Pliocene.

Paleomagnetic and stable isotope measurements and distribution of benthic foraminifera in sediment core PS1388-3 from the Antarctic continental margin in the eastern Weddell Sea

A stable isotope record from the eastern Weddell Sea from 69°S is presented. For the first time, a 250,000-yr record from the Southern Ocean can be correlated in detail to the global isotope stratigraphy. Together with magnetostratigraphic, sedimentological and micropalaeontological data, the stratigraphic control of this record can be extended back to 910,000 yrs B.P. A time scale is constructed by linear interpolation between confirmed stratigraphic data points. The benthic d18O record (Epistominella exigua) reflects global continental ice volume changes during the Brunhes and late Matuyama chrons, whereas the planktonic isotopic record (Neogloboquadrina pachyderma) may be influenced by a meltwater lid caused by the nearby Antarctic ice shelf and icebergs. The worldwide climatic improvement during deglaciations is documented in the eastern Weddell Sea by an increase in production of siliceous plankton followed, with a time lag of approximately 10,000 yrs, by planktonic foraminifera production. Peak values in the difference between planktonic and benthic d13C records, which are 0.5 per mil higher during warm climatic periods than during times with expanded continental ice sheets, also suggest increased surface productivity during interglacials in the Southern Ocean.

Sea surface temperatures derived from alkenones from Late Quaternary sediments of the East Equatorial South Atlantic

Angola Basin and Walvis Ridge records of past sea surface temperatures (SST) derived from the alkenone Uk 37 index are used to reconstruct the surface circulation in the east equatorial South Atlantic for the last 200,000 years. Comparison of SST estimates from surface sediments between 5° and 20°S with modern SST data suggests that the alkenone temperatures represent annual mean values of the surface mixed layer. Alkenone-derived temperatures for the warm climatic maxima of the Holocene and the penultimate interglacial are 1 to 4°C higher than latest Holocene values. All records show glacial to interglacial differences of about 3.5°C in annual mean SST, which is about 1.5°C greater than the difference estimated by CLIMAP (1981) for the eastern Angola Basin. At the Walvis Ridge, significant SST variance is observed at all of the Earth's orbital periodicities. SST records from the Angola Basin vary predominantly at 23- and 100-kyr periodicities. For the precessional cycle, SST changes at the Walvis Ridge correspond to variations of boreal summer insolation over Africa and lead ice volume changes, suggesting that the east equatorial South Atlantic is sensitive to African monsoon intensity via trade-wind zonality. Angola Basin SST records lag those from the Walvis Ridge and the equatorial Atlantic by about 3 kyr. The comparison of Angola Basin and Walvis Ridge SST records implies that the Angola-Benguela Front (ABF) (currently at about 14-16°S) has remained fairly stationary between 12° and 20°S (the limits of our cores) during the last two glacial-interglacial cycles. The temperature contrast associated with the ABF exhibits a periodic 23-kyr variability which is coherent with changes in boreal summer insolation over Africa. These observations suggest that surface waters north of the present ABF have not directly responded to monsoon-modulated changes in the trade-wind vector, that the central field of zonally directed trades in the southern hemisphere was not shifted or extended northward by several degrees of latitude during glacials, and that a cyclonic gyre circulation has existed in the east equatorial South Atlantic over the last 200,000 years. This scenario contradicts former assumptions of glacial intensification of the Benguela Current into the eastern Angola Basin and increased coastal upwelling off Angola.

Benthic and planktic foraminiferal stable isotope record and coccolith abundance spanning the last 500,000 years of ODP Hole 121-758C

The Indian Summer Monsoon (ISM) is an inter-hemispheric and highly variable ocean-atmosphere-land interaction that directly affects the densely populated Indian subcontinent. Here, we present new records of palaeoceanographic variability that span the last 500,000 years from the eastern equatorial Indian Ocean, a relatively under-sampled area of ISM influence. We have generated carbon and oxygen stable isotope records from three foraminiferal species from Ocean Drilling Program Site 758 (5°N, 90°E) to investigate the oceanographic history of this region. We interpret our resultant Dd18O (surface-thermocline) record of upper water-column stratification in the context of past ISM variability, and compare orbital phase relationships in our Site 758 data to other climate and monsoon proxies in the region. Results suggest that upper water-column stratification at Site 758, which is dominated by variance at precession and half-precession frequencies (23, 19 and 11 ka), is forced by both local (5°N) insolation and ISM winds. In the precession (23 ka) band, stratification minima at Site 758 lag northern hemisphere summer insolation maxima (precession minima) by 9 ka, which is consistent with Arabian Sea ISM phase estimates and suggests a common wind forcing in both regions. This phase implicates a strong sensitivity to both ice volume and southern hemisphere insolation forcing via latent heat export from the southern subtropical Indian Ocean. Additionally, we find evidence of possible overprinting of millennial-scale events during glacial terminations in our stratification record, which suggests an influence of remote abrupt climate events on ISM dynamics.

Sinking rates of particles measured from deployments in the Atlantic Ocean based on seasonal data

The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opal-rich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of 0.29 Tg per year down to 3000 m off the NW African upwelling region between 5 and 35° N. Simple parameterisations of remineralisation and sinking rates in such models, however, limit their capability in reproducing the flux variation in the water column.

Sea-surface temperature reconstruction for sediment core GIK18287-3 in the tropical South China Sea

The timing and magnitude of sea-surface temperature (SST) changes in the tropical southern South China Sea (SCS) during the last 16,500 years have been reconstructed on a high-resolution, 14C-dated sediment core using three different foraminiferal transfer functions (SIMMAX28, RAM, FP-12E) and geochemical (Uk'37) SST estimates. In agreement with CLIMAP reconstructions, both the FP-12E and the Uk'37 SST estimates show an average late glacial-interglacial SST difference of 2.0°C, whereas the RAM and SIMMAX28 foraminiferal transfer functions show only a minor (0.6°C) or no consistent late glacial-interglacial SST change, respectively. Both the Uk'37 and the FP-12E SST estimates, as well as the planktonic foraminiferal delta18O values, indicate an abrupt warming (ca. 1°C in <200 yr) at the end of the last glaciation, synchronous (within dating uncertainties) with the Bølling transition as recorded in the Greenland Ice Sheet Project 2 (GISP2) ice core, whereas the RAM-derived deglacial SST increase appears to lag during this event by ca. 500 yr. The similarity in abruptness and timing of the warming associated with the Bølling transition in Greenland and the southern SCS suggest a true synchrony of the Northern Hemisphere warming at the end of the last glaciation. In contrast to the foraminiferal transfer function estimates that do not indicate any consistent cooling associated with the Younger Dryas (YD) climate event in the tropical SCS, the Uk'37 SST estimates show a cooling of ca. 0.2-0.6°C compared to the Bølling-Allerød period. These Uk'37 SST estimates from the southern SCS argue in favor of a Northern Hemisphere-wide, synchronous cooling during the YD period.

Stable isotope records and biogenic barium fluxes of sediment core SO202-07-06

Reduced nitrate supply to the subarctic North Pacific (SNP) surface during the last ice age has been inferred from coupled changes in diatom-bound d15N (DB-d15N), bulk sedimentary d15N, and biogenic fluxes. However, the reliability of bulk sedimentary and DB-d15N has been questioned, and a previously reported d15N minimum during Heinrich Stadial 1 (HS1) has proven difficult to explain. In a core from the western SNP, we report the foraminifera-bound d15N (FB-d15N) in Neogloboquadrina pachyderma and Globigerina bulloides, comparing them with DB-d15N in the same core over the past 25 kyr. The d15N of all recorders is higher during the Last Glacial Maximum (LGM) than in the Holocene, indicating more complete nitrate consumption. N. pachyderma FB-d15N is similar to DB-d15N in the Holocene but 2.2 per mil higher during the LGM. This difference suggests a greater sensitivity of FB-d15N to changes in summertime nitrate drawdown and d15N rise, consistent with a lag of the foraminifera relative to diatoms in reaching their summertime production peak in this highly seasonal environment. Unlike DB-d15N, FB-d15N does not decrease from the LGM into HS1, which supports a previous suggestion that the HS1 DB-d15N minimum is due to contamination by sponge spicules. FB-d15N drops in the latter half of the Bølling/Allerød warm period and rises briefly in the Younger Dryas cold period, followed by a decline into the mid-Holocene. The FB-d15N records suggest that the coupling among cold climate, reduced nitrate supply, and more complete nitrate consumption that characterized the LGM also applied to the deglacial cold events.

Bohrungen Wasserwerk Rantrum

Nachdem zwischen den Salinarstrukturen von Heide und Albersdorf in ein ein ausgedehnten Kaolinsandvorkommen neben dem schon lange bestehenden Wasserwerk der Stadt Heide die Wasserwerke Linden (Wasserbeschaffungsverband Lunden-Hennstedt) und Nordhastedt (DEA) errichtet werden konnten und ein weiteres in Erfde geplant ist, lag es nahe, am Rand der Husumer Geest zwischen den Strukturen Oldenswort-Mildstedt und Heide-Hollingstedt ein ähnliches Vorkommen für die Wasserversorgung von Eiderstedt zu erschließen. In älteren Bohrungen waren Kaolinsande in größerer Mächtigkeit bereits im Untereidergebiet nachgewiesen worden.

(Table 1) Age control points of ODP Site 160-968

The astronomical timescale of the Eastern Mediterranean Plio-Pleistocene builds on tuning of sapropel layers to Northern Hemisphere summer insolation maxima. A 3000-year precession lag has become instrumental in the tuning procedure as radiocarbon dating revealed that the midpoint of the youngest sapropel, S1, in the early Holocene occurred approximately 3000 years after the insolation maximum. The origin of the time lag remains elusive, however, because sapropels are generally linked to maximum African monsoon intensities and transient climate modeling results indicate an in-phase behavior of the African monsoon relative to precession forcing. Here we present new high-resolution records of bulk sediment geochemistry and benthic foraminiferal oxygen isotopes from ODP Site 968 in the Eastern Mediterranean. We show that the 3000-year precession time lag of the sapropel midpoints is consistent with (1) the global marine isotope chronology, (2) maximum (monsoonal) precipitation conditions in the Mediterranean region and China derived from radiometrically dated speleothem records, and (3) maximum atmospheric methane concentrations in Antarctica ice cores. We show that the time lag relates to the occurrence of precession-paced North Atlantic cold events, which systematically delayed the onset of strong boreal summer monsoon intensity. Our findings may also explain a non-stationary behavior of the African monsoon over the past 3 million years due to more frequent and intensive cold events in the Late Pleistocene.