ALBERT

Description: Dam removal has been demonstrated as one of the most frequent and effective fluvial restoration actions but at most dam removals, especially of small dams, there has been little geomorphological monitoring. The results of the geomorphological monitoring implemented in two dams in Urumea and Leitzaran Rivers (northern Spain) are presented. The one from Urumea River, originally 3.5 m high, impounded 500 m of river course, was removed instantaneously whereas that in Leitzaran River, was 12.5 m high, impounded 1,500 m of river course, and it is in its second phase of a 4-stage removal process. Changes in channel morphology, sediment size and mobility and river bed morphologies were assessed. The monitoring included different techniques: topographical measurements of the channel, terrestrial laser scanner measurements of river bed and bars, sediment grain size and transport; all of them repeated in four (May, August, November 2011 and May 2012) and five (July and September 2013, April and August 2014 and June 2015 fieldwork campaigns in Urumea and Leitzaran Rivers, respectively. Geomorphic responses of both dam removals are presented, as well as compared between them. Morphological channel adjustments occurred mainly shortly after dam removals, but with differences among the one removed instantaneously, that was immediate, whereas that conducted by stages took longer. Degradational processes were observed upstream of both dams (up to 1.2 m and 4 m in Urumea and Leitzaran Rivers, respectively), but also aggradational processes (pool filling), upstream of Inturia dam (2.85 m at least). Less evident aggradational processes were observed downstream of the dams (up to 0.37 m and 0.50 m in Urumea and Leitzaran Rivers, respectively). Flood events, specially a 100-year one registered during the monitoring period of Mendaraz dam removal, reactivated geomorphological processes as incision and bank erosion, whereas longitudinal profile recovery, grain-size sorting and upstream erosion took longer. This article is protected by copyright. All rights reserved.

Description: In the interphase nucleus of metazoan cells DNA is organized in supercoiled loops anchored to a nuclear matrix (NM). DNA loops are operationally classified in structural and facultative. Varied evidence indicates that DNA replication occurs in replication foci organized upon the NM and that structural DNA loops may correspond to the replicons in vivo. In normal rat liver the hepatocytes are arrested in G0 but synchronously re-enter the cell cycle after partial-hepatectomy leading to liver regeneration. Using this model we have previously determined that the DNA loops corresponding to a gene-rich genomic region move in a sequential fashion towards the NM during replication and then return to their original configuration in newly quiescent cells, once liver regeneration has been achieved. In the present work we determined the organization into structural DNA loops of a gene-poor region centered on c-myc and tracked-down its movement at the peak of S phase and after the return to cellular quiescence during and after liver regeneration. The results confirmed that looped DNA moves towards the NM during replication but in this case the configuration of the gene-poor region into DNA loops becomes reorganized and after replication only the loop containing c-myc resembles the original in the control G0 hepatocytes. Our results suggest that the local chromatin configuration around potentially active genes constraints the formation of specific structural DNA loops after DNA replication, while in non-coding regions the structural DNA loops are only loosely determined after DNA replication by structural constraints that modulate the DNA-NM interactions. J. Cell. Biochem. © 2012 Wiley Periodicals, Inc.

Description: The Cova Gran de Santa Linya (Lleida, Spain) is a recently discovered site, with a broad chrono-cultural sequence that contains archaeological levels dating to the Middle Palaeolithic, Early Upper Palaeolithic, Late Upper Palaeolithic, Neolithic and Early Bronze Age. We present the chronometric and stratigraphic context of these occupations, which were dated using 14 C accelerator mass spectrometry and thermoluminescence. The sequence provides important indicators that aid in the reconstruction of the history of human occupation on the southern slopes of the Spanish Pyrenees over the past 50,000 years. Copyright © 2011 John Wiley & Sons, Ltd.

Description: This paper examines the dynamics of large-scale overturning circulations in the tropical atmosphere using an idealized zonally symmetric model on the equatorial β-plane. Under certain simplifications of its coefficients, the elliptic partial differential equation for the transverse circulation can be solved by first performing a vertical transform to obtain a horizontal structure equation, and then using Green's function to solve the horizontal structure equation. When deep diabatic heating is present in the Intertropical Convergence Zone (ITCZ), the deep Hadley circulation is of first order importance. In the absence of deep diabatic heating, the interior circulation associated with Ekman pumping cannot penetrate deep into the troposphere because the resistance of fluid parcels to horizontal motion (i.e., inertial stability) is significantly smaller than their resistance to vertical motion (i.e., static stability). In this scenario, only a shallow Hadley circulation exists. The shallow overturning circulation is characterized by meridional velocities as large as 7 m s -1 at the top of the boundary layer, in qualitative agreement with observations in the tropical eastern Pacific. The meridional asymmetry between the winter and summer deep and shallow Hadley cells is attributed to the anisotropy of the inertial stability parameter, and as the ITCZ widens meridionally or as the forcing involves higher vertical wavenumbers, the asymmetry between the winter and summer cells increases.

Description: Statistical and heat budget methods for analyzing temperature dynamics of creeks are limited by the ability to resolve thermal processes and fine-grained thermal structures, respectively. Here we describe a hybrid method that identifies distinct thermal components in a stream's heat budget using only temperature data and an algorithm that employs mutual information to “unmix” signals in the temperature data. Spatial resolution is limited only by the number of temperature-logging sensors, which can be quite high for distributed-temperature sensors. Process resolution is at the level of thermal components, defined as distinct collections of heat flux elements sharing coordinated (nonindependent) dynamics. Inference can be used to relate thermal components to meteorological forcing and structural heterogeneity in the fluvial system and to suggest novel hypotheses for further testing with targeted heat budget studies. Applying the method to a small, arid-land creek produced two novel hypotheses: (1) lateral conduction of heat from adjacent dry land (bed, terraces) appeared to cause a substantial heating of the stream, augmented by off-channel flow paths, and (2) riparian vegetation was associated with a subtraction of heat from the stream at a rate proportionate to solar insolation, exceeding the maximum decoupling effect of shade by at least 2°C at midday, and suggesting upwelling heat flux from water to tree canopy proportional to sunlight. The method appears useful for generating new hypotheses, for selecting informative sites for detailed heat budgets, for determining the dimensionality of heat budgets in natural streams, and more broadly for associating thermal components to fluvial structure and processes.

Description: Climate change has already altered the distribution of marine fishes. Future predictions of fish distributions and catches based on bioclimate envelope models are available, but to date they have not considered inter-specific interactions. We address this by combining the species-based Dynamic Bioclimate Envelope Model (DBEM) with a size-based trophic model. The new approach provides spatially and temporally resolved predictions of changes in species’ size, abundance and catch potential that account for the effects of ecological interactions. Predicted latitudinal shifts are, on average, reduced by 20% when species interactions are incorporated, compared to DBEM predictions, with pelagic species showing the greatest reductions. Goodness-of-fit to biomass data from fish stock assessments in the North Atlantic between 1991 and 2003 is improved slightly by including species interactions. The differences between predictions from the two models may be relatively modest because, at the North Atlantic basin scale, (1) predators and competitors may respond to climate change together; (2) existing parameterization of the DBEM might implicitly incorporate trophic interactions; and/or (3) trophic interactions might not be the main driver of responses to climate. Future analyses using ecologically-explicit models and data will improve understanding of the effects of inter-specific interactions on responses to climate change, and better inform managers about plausible ecological and fishery consequences of a changing environment. This article is protected by copyright. All rights reserved.

Description: This paper presents analytical solutions of large-scale, zonally symmetric overturning circulations in the tropical free troposphere forced by transient diabatic heating in the off-equatorial intertropical convergence zone (ITCZ). The dynamics are discussed in the context of the time dependent meridional circulation equation arising in an equatorial $\beta$-plane model. The solutions of these differential equations contain terms for the slow, quasi-balanced part of the response and terms for the transient, zonally symmetric, inertia-gravity wave part of the response. When the off-equatorial (north of the equator) ITCZ diabatic heating is switched on at various rates, both parts of the response reveal a basic asymmetry between the southern and northern hemispheres, with the southern hemisphere side containing most of the quasi-balanced compensating subsidence and transient inertia-gravity wave activity. The inertia-gravity waves travel in wave packets that bounce off a spectrum of turning latitudes, and are analyzed in the context of an average conservation law approach. These traveling wave packets cause the mass flux in the southern and northern Hadley cells to pulsate on timescales of about one, two, and three days for diabatic heating of the external, first internal, and second internal vertical modes, respectively. The spectral characteristics of the vertical motion in the ITCZ and subsidence regions are slightly more complicated and depend on ITCZ location. This article is protected by copyright. All rights reserved.

Description: [1]  Statistical and heat budget methods for analyzing temperature dynamics of creeks are limited by the ability to resolve thermal processes and fine-grained thermal structures, respectively. Here we describe a hybrid method that identifies distinct thermal components in a stream's heat budget using only temperature data and an algorithm that employs mutual information to “unmix” signals in the temperature data. Spatial resolution is limited only by the number of temperature-logging sensors, which can be quite high for distributed-temperature sensors. Process resolution is at the level of thermal components, defined as distinct collections of heat flux elements sharing coordinated (nonindependent) dynamics. Inference can be used to relate thermal components to meteorological forcing and structural heterogeneity in the fluvial system and to suggest novel hypotheses for further testing with targeted heat budget studies. Applying the method to a small, arid-land creek produced two novel hypotheses: (1) lateral conduction of heat from adjacent dry land (bed, terraces) appeared to cause a substantial heating of the stream, augmented by off-channel flow paths, and (2) riparian vegetation was associated with a subtraction of heat from the stream at a rate proportionate to solar insolation, exceeding the maximum decoupling effect of shade by at least 2°C at midday, and suggesting upwelling heat flux from water to tree canopy proportional to sunlight. The method appears useful for generating new hypotheses, for selecting informative sites for detailed heat budgets, for determining the dimensionality of heat budgets in natural streams, and more broadly for associating thermal components to fluvial structure and processes.