TY - JOUR A1 - Fiener, P. A1 - Wilken, F. A1 - Aldana-Jague, E. A1 - Deumlich, D. A1 - Gomez, J. A. A1 - Guzman, G. A1 - Hardy, R. A. A1 - Quinton, J. N. A1 - Sommer, M. A1 - Van Oost, K. A1 - Wexler, R. T1 - Uncertainties in assessing tillage erosion BT - how appropriate are our measuring techniques? JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Tillage erosion on arable land is a very important process leading to a net downslope movement of soil and soil constitutes. Tillage erosion rates are commonly in the same order of magnitude as water erosion rates and can be even higher, especially under highly mechanized agricultural soil management. Despite its prevalence and magnitude, tillage erosion is still understudied compared to water erosion. The goal of this study was to bring together experts using different techniques to determine tillage erosion and use the different results to discuss and quantify uncertainties associated with tillage erosion measurements. The study was performed in northeastern Germany on a 10 m by 50 m plot with a mean slope of 8%. Tillage erosion was determined after two sequences of seven tillage operations. Two different micro-tracers (magnetic iron oxide mixed with soil and fluorescent sand) and one macro-tracer (passive radio-frequency identification transponders (RFIDs), size: 4 x 22 mm) were used to directly determine soil fluxes. Moreover, tillage induced changes in topography were measured for the entire plot with two different terrestrial laser scanners and an unmanned aerial system for structure from motion topography analysis. Based on these elevation differences, corresponding soil fluxes were calculated. The mean translocation distance of all techniques was 0.57 m per tillage pass, with a relatively wide range of mean soil translocation distances ranging from 039 to 0.72 m per pass. A benchmark technique could not be identified as all used techniques have individual error sources, which could not be quantified. However, the translocation distances of the macro-tracers used were consistently smaller than the translocation distances of the micro-tracers (mean difference = -26 +/- 12%), which questions the widely used assumption of non-selective soil transport via tillage operations. This study points out that tillage erosion measurements, carried out under almost optimal conditions, are subject to major uncertainties that are far from negligible. (C) 2018 Elsevier B.V. All rights reserved. KW - Tillage erosion KW - Tracer KW - UAS KW - TLS KW - Method comparison KW - Measurement uncertainty Y1 - 2018 U6 - https://doi.org/10.1016/j.geomorph.2017.12.031 SN - 0169-555X SN - 1872-695X VL - 304 SP - 214 EP - 225 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Martinez-Valdes, Eduardo Andrés A1 - Guzman-Venegas, R. A. A1 - Silvestre, R. A. A1 - Macdonald, J. H. A1 - Falla, D. A1 - Araneda, O. F. A1 - Haichelis, D. T1 - Electromyographic adjustments during continuous and intermittent incremental fatiguing cycling JF - Psychotherapeut N2 - We studied the sensitivity of electromyographic (EMG) variables to load and muscle fatigue during continuous and intermittent incremental cycling. Fifteen men attended three laboratory sessions. Visit 1: lactate threshold, peak power output, and VO2max. Visits 2 and 3: Continuous (more fatiguing) and intermittent (less fatiguing) incremental cycling protocols [20%, 40%, 60%, 80% and 100% of peak power output (PPO)]. During both protocols, multichannel EMG signals were recorded from vastus lateralis: muscle fiber conduction velocity (MFCV), instantaneous mean frequency (iMNF), and absolute and normalized root mean square (RMS) were analyzed. MFCV differed between protocols (P<0.001), and only increased consistently with power output during intermittent cycling. RMS parameters were similar between protocols, and increased linearly with power output. However, only normalized RMS was higher during the more fatiguing 100% PPO stage of the continuous protocol [continuous-intermittent mean difference (95% CI): 45.1 (8.5% to 81.7%)]. On the contrary, iMNF was insensitive to load changes and muscle fatigue (P=0.14). Despite similar power outputs, continuous and intermittent cycling influenced MFCV and normalized RMS differently. Only normalized RMS was sensitive to both increases in power output (in both protocols) and muscle fatigue, and thus is the most suitable EMG parameter to monitor changes in muscle activation during cycling. KW - Fatigue KW - surface electromyography KW - muscle fiber conduction velocity KW - amplitude KW - frequency spectrum Y1 - 2016 U6 - https://doi.org/10.1111/sms.12578 SN - 0905-7188 SN - 1600-0838 VL - 26 SP - 1273 EP - 1282 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Guzman, S. A1 - Petrinovic, I. A. A1 - Brod, J. A. A1 - Hongn, Fernando D. A1 - Seggiaro, R. E. A1 - Montero, C. A1 - Carniel, Roberto A1 - Dantas, E. L. A1 - Sudo, Masafumi T1 - Petrology of the Luingo caldera (SE margin of the Puna plateau) a middle Miocene window of the arc-back arc configuration JF - Journal of volcanology and geothermal research N2 - We describe the petrographic characteristics, whole-rock geochemistry and mineral chemistry of rocks from the Pucarilla-Cerro Tipillas Volcanic Complex with emphasis on the rocks belonging to the middle Miocene Luingo caldera, located in the south-eastern portion of the Central Volcanic Zone (CVZ) of the Andes. We modelled the petrogenesis of the Luingo caldera rocks as a mixture of ca. 20% crustal magmas and 80% of mantle magmas by AFC with recharge processes. A comparison of Luingo geochemical data with the composition of Miocene-Pliocene volcanic rocks from the broad area, points to major thickening events during the middle Miocene for the western portion and during the upper Miocene for the eastern portion of the Southern CVZ. In the eastern sector (similar to 66 degrees W) the mantle source appears to change from a spinel-lherzolite type for the middle Miocene to a garnet-lherzolite type for the upper Miocene-Pliocene magmas. The areal distribution of the volcanic products led to the recognition of approximately equivalent areas covered by volcanic rocks both in the eastern and in the western Puna borders. This indicates a broad arc, which was structurally controlled at the proto-Puna/Puna margins, whose geochemical differences are related with variations in crustal thicknesses and heterogeneous mantle sources from west to east. KW - Luingo caldera KW - Central Andes KW - Miocene volcanism KW - Southern Central Volcanic Zone KW - crustal thickness Y1 - 2011 U6 - https://doi.org/10.1016/j.jvolgeores.2010.12.008 SN - 0377-0273 VL - 200 IS - 3-4 SP - 171 EP - 191 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Quandt, Dennis A1 - Trumbull, Robert B. A1 - Altenberger, Uwe A1 - Cardona, Agustin A1 - Romer, Rolf L. A1 - Bayona, Germán A. A1 - Ducea, Mihai N. A1 - Valencia, Victor A1 - Vasquez, Monica A1 - Cortes, Elizabeth A1 - Guzman, Georgina T1 - The geochemistry and geochronology of Early Jurassic igneous rocks from the Sierra Nevada de Santa Marta, NW Colombia, and tectono-magmatic implications JF - Journal of South American earth sciences N2 - The Sierra Nevada de Santa Marta in NW Colombia is an isolated massif at the northernmost end of the Andes chain near the boundary with the Caribbean plate. Previous geologic mapping and K-Ar dating have shown that Jurassic plutonic and volcanic units make up a large part of the Santa Marta Massif (SMM). These rocks have been considered to be part of a Jurassic magmatic arc extending from NW Colombia to northern Chile, but without any geochemical basis for comparison. This paper reports on a geochemical and Sr-Nd-Pb isotope study of the Jurassic rocks in the SMM and provides 12 new U-Pb zircon ages from in-situ laser ICP-MS dating. The plutonic and volcanic units span a range from 45 to 78 wt.% SiO2, with a dominance of intermediate to felsic compositions with SiO2 > 57 wt.%. They classify as calc-alkaline, medium to high-K, metaluminous rocks with trace-element features typical for arc-derived magma series. In terms of their major and trace-element compositions, the SMM Jurassic units overlap with contemporary plutonic and volcanic rocks from other regions of the Central and Eastern Cordilleras of Colombia, and confirm an arc affinity. The new U-Pb ages range from 176 +/- 1 Ma to 192 +/- 2 Ma (n = 12), with most between 180 and 188 Ma (n = 7). The initial Sr isotope ratios (at 180 Ma) are between 0.7012 and 0.7071 (n = 29), with 3 outliers attributed to mobilization of Rb and/or Sr, Nearly all samples have negative( )epsilon Nd-(180) values between - 10.3 and 0.0 (n = 30), the two exceptions being only slightly positive (1.1 and 1.9). Measured Pb isotope ratios fall in a narrow range, with Pb-206/Pb-204 from 18.02 to 19.95, (207) Pb/(204) Pb from 15.56 to 15.67 and Pb-208/Pb-204 from 37.76 to 39.04 (n = 28). In the regional context of previous studies, these results confirm early Jurassic ages and an arc affinity for the widespread magmatism exposed in the eastern and northeastern Colombian Andes. We also note patterns in the distribution and composition of magmas. The magmatic activity in the Central Cordillera tends to be younger than in the Eastern Cordillera and is spatially more restricted to the vicinity of regional fault systems. In terms of composition, Jurassic igneous rocks in the Eastern Cordillera have systematically lower epsilon Nd-(180) values than those from the Central Cordillera, whereas the Pb isotope ratios overlap. We ascribe the Nd isotope variations to heterogeneity in the mantle source and/or degree of crustal contamination, whereas the Pb isotope ratios are crust-dominated and similar throughout the region. The spatio-temporal and compositional evolution of Jurassic magmatic rocks in the Northern Andes reflect the major plate kinematic readjustment between the Triassic and the Early Jurassic in the proto-Andean margin. KW - Jurassic arc KW - Northern Andes KW - Sr-Nd-Pb isotopes KW - Geochronology Y1 - 2018 U6 - https://doi.org/10.1016/j.jsames.2018.06.019 SN - 0895-9811 VL - 86 SP - 216 EP - 230 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Lopez, S. A1 - Reimers, Dieter A1 - Gregg, M. D. A1 - Wisotzki, Lutz A1 - Wucknitz, Olaf A1 - Guzman, A. T1 - Metal abundances in a damped Ly alpha system along two lines of sight at z=0.93 N2 - We study metal abundances in the z = 0.9313 damped Ly alpha system observed along the two lines of sight, A and B, toward the gravitationally lensed double QSO HE 0512-3329. Spatially resolved Space Telescope Imaging Spectrograph spectra constrain the neutral-gas column density to be N(H I) = 1020.5 cm(-2) in both A and B. UV-visual Echelle Spectrograph spectra ( spectral resolution FWHM = 9.8 km s(-1)) show, in contrast, significant line-of-sight differences in the column densities of Mn II and Fe II; these are not due to observational systematics. We find that [Mn/H] = -1.44 and [Fe/H] = -1.52 in damped Ly alpha system A, while [Mn/H] = -0.98 and [Fe/H] > -1.32, and possibly as high as [Fe/H] approximate to -1, in damped Ly alpha system B. A careful assessment of possible systematic errors leads us to conclude that these transverse differences are significant at a 5 sigma level or greater. Although nucleosynthesis effects may also be at play, we favor differential dust depletion as the main mechanism producing the observed abundance gradient. The transverse separation is 5 h(70)(-1) kpc at the redshift of the absorber, which is also likely to be the lensing galaxy. The derived abundances therefore probe two opposite sides of a single galaxy hosting both damped Ly alpha systems. This is the first time firm abundance constraints have been obtained for a single damped system probed by two lines of sight. The significance of this finding for the cosmic evolution of metals is discussed Y1 - 2005 SN - 0004-637X ER - TY - JOUR A1 - Hinz, Carsten A1 - Guzmán, Renán A. Oliva A1 - Müller, Heike T1 - Zur Förderung des wissenschaftlichen Nachwuchses in der haushaltsbezogenen Bildung BT - Situationsbeschreibung aus einer Perspektive der HaBiFo-NEO Nachwuchsgruppe JF - Haushalt in Bildung und Forschung N2 - Wissenschaftlicher Nachwuchs ist bedeutsam für den Erhalt und Ausbau jeder Disziplin. Aktuell gibt es nur wenige empirische Erkenntnisse zur Situation in der haushaltsbezogenen Bildung. Im Beitrag werden ausgewählte Aspekte zur Situation der Nachwuchsförderung skizziert und Anknüpfungspunkte für die haushaltsbezogene Bildung vor dem Hintergrund erster Erfahrungen aus der 2019 gegründeten Nachwuchsgruppe HaBiFo-NEO diskutiert. N2 - Junior researchers are important for securing and expanding any discipline. Currently, there is little empirical evidence on their situation in household education. This article outlines selected aspects of promoting junior researchers and discusses focal points for household education against the backdrop of initial experiences from the HaBiFo-NEO junior researcher group founded in 2019. T2 - On the promotion of junior researchers in household education KW - Akademischer Nachwuchs KW - Nachwuchswissenschaftler KW - haushaltsbezogene Bildung KW - Ernährungs- und Verbraucherbildung KW - Fachdidaktik KW - junior scholars KW - early career scientists KW - food and nutrition education KW - consumer studies KW - subject-matter didactics Y1 - 2021 U6 - https://doi.org/10.3224/hibifo.v10i1.01 VL - 10 IS - 1 SP - 3 EP - 23 PB - Budrich CY - Opladen ER - TY - JOUR A1 - Guzman, Diego A. A1 - Samprogna Mohor, Guilherme A1 - Mendiondo, Eduardo Mario T1 - Multi-year index-based insurance for adapting Water Utility Companies to hydrological drought BT - case study of a water supply system of the Sao Paulo metropolitan region, Brazil JF - Water N2 - The sustainability of water utility companies is threatened by non-stationary drivers, such as climate and anthropogenic changes. To cope with potential economic losses, instruments such as insurance are useful for planning scenarios and mitigating impacts, but data limitations and risk uncertainties affect premium estimation and, consequently, business sustainability. This research estimated the possible economic impacts of business interruption to the Sao Paulo Water Utility Company derived from hydrological drought and how this could be mitigated with an insurance scheme. Multi-year insurance (MYI) was proposed through a set of "change" drivers: the climate driver, through forcing the water evaluation and planning system (WEAP) hydrological tool; the anthropogenic driver, through water demand projections; and the economic driver, associated with recent water price policies adopted by the utility company during water scarcity periods. In our study case, the evaluated indices showed that MYI contracts that cover only longer droughts, regardless of the magnitude, offer better financial performance than contracts that cover all events (in terms of drought duration). Moreover, through MYI contracts, we demonstrate solvency for the insurance fund in the long term and an annual average actuarially fair premium close to the total expected revenue reduction. KW - multi-year insurance KW - climate change KW - hydrological drought KW - water KW - security and economy Y1 - 2020 U6 - https://doi.org/10.3390/w12112954 SN - 2073-4441 VL - 12 IS - 11 PB - MDPI CY - Basel ER - TY - JOUR A1 - Guzman, Silvina A1 - Strecker, Manfred A1 - Marti, Joan A1 - Petrinovic, Ivan A. A1 - Schildgen, Taylor F. A1 - Grosse, Pablo A1 - Montero-Lopez, Carolina A1 - Neri, Marco A1 - Carniel, Roberto A1 - D. Hongn, Fernando A1 - Muruaga, Claudia A1 - Sudo, Masafumi T1 - Construction and degradation of a broad volcanic massif: The Vicuna Pampa volcanic complex, southern Central Andes, NW Argentina JF - Geological Society of America bulletin N2 - The Vicuna Pampa volcanic complex, at the SE edge of the arid Puna Plateau of the Central Andes, records the interplay between volcanic construction and degra-dational processes. The low-sloping Vicuna Pampa volcanic complex, with a 1200-m-deep, southeastward-opening depression, was previously interpreted as a collapse caldera based on morphological considerations. However, characteristic features associated with collapse calderas do not exist, and close inspection instead suggests that the Vicuna Pampa volcanic complex is a strongly eroded, broad, massif-type composite volcano of mainly basaltic to trachyandesitic composition. Construction of the Vicuna Pampa volcanic complex occurred during two distinct cycles separated by the development of the depression. The first and main cycle took place at ca. 12 Ma and was dominated by lava flows and subordinate scoria cones and domes. The second cycle, possibly late Miocene in age, affected the SW portion of the depression with the emplacement of domes. We interpret the central depression as the result of a possible sector collapse and subsequent intense fluvial erosion during middle to late Miocene time, facilitated by faulting, steepened topography, and wetter climate conditions compared to today. We estimate that similar to 65% of the initial edifice of similar to 240 km(3) was degraded. The efficiency of degradation processes for removing mass from the Vicuna Pampa volcanic complex is surprising, considering that today the region is arid, and the stream channels within the complex are predominantly transport limited, forming a series of coalesced, aggraded alluvial fans and eolian infill. Hence, the Vicuna Pampa volcanic complex records the effects of past degradation efficiency that differs substantially from that of today. Y1 - 2017 U6 - https://doi.org/10.1130/B31631.1 SN - 0016-7606 SN - 1943-2674 VL - 129 SP - 750 EP - 766 PB - American Institute of Physics CY - Boulder ER -