New tools for online teaching and their impact on student learning

[EN] In the context of the global Covid-19 crisis, a practical introductory Geosciences course was redesigned to aid student learning in a 100% virtual format. New materials were created to i) improve disciplinary language range and concept acquisition; ii) make classes more dynamic; iii) provide tools for self-regulated learning and assessment and iv) maintain student motivation. Usefulness of the new materials was evaluated using a voluntary online survey that was answered by 40% of the students. Additional information was obtained from the university's student evaluation survey. All tools were well-rated, but self-assessment quizzes and class presentations had the highest overall scores. Students commented on their usefulness in terms of knowledge acquisition and self-assessment. Perhaps not surprisingly, self-assessment quizzes were the one tool students felt kept them more motivated. These were closely followed by class presentations and short in-class quizzes. Students found the online access to all lesson materials very useful for self-paced learning. According to a majority of students, the in-class quizzes and student participation using the digital the whiteboard made classes more dynamic. Overall, the new strategies succeeded in improving students' learning and independence, but more work is needed to make classes more dynamic, and especially to improve student motivation. Intrinsic motivation is perhaps the most difficult to improve because in a 100% virtual course, it is difficult to promote student-student interactions and receive visual feedback from the class. In view of the survey results, we introduce bonus activities in order to improve extrinsic motivation.Huguet, C.; Pearse, J.; Esteve, J. (2021). New tools for online teaching and their impact on student learning. En 7th International Conference on Higher Education Advances (HEAd'21). Editorial Universitat Politècnica de València. 163-170. https://doi.org/10.4995/HEAd21.2021.12811OCS16317

Constraints in the application of the Branched and Isoprenoid Tetraether index as a terrestrial input proxy

Determination of the relative inputs of aquatic autochthonous and terrestrial allochthonous organic matter into marine and lacustrine environments is essential to understanding the global carbon budget. A variety of proxies are used for this purpose, including the Branched and Isoprenoid Tetraether (BIT) index. This is calculated from the concentrations of branched glycerol dialkyl glycerol tetraethers (GDGTs), derived from unidentified terrestrial bacteria, and crenarchaeol, a marker for aquatic mesophile Thaumarchaeota (Crenarchaeota group I). As the index is a ratio, its value depends on both the crenarchaeol aquatic in situ production and the soil-derived branched GDGT input. Therefore, the BIT index reflects not only changes in the input of terrestrial or soil organic matter but also relative variations in aquatic Thaumarchaeota abundance in the water column. In fact, we show that in oceanic and lacustrine settings, the BIT index can be dominated by the aquatic end-member of the ratio. Consequently, the BIT index by itself can be an unreliable proxy to compare the input of terrestrial matter between sites and over time, and we propose that the quantification of branched GDGT fluxes or concentrations may instead be a better indicator of soil terrestrial inputs

Archaeal membrane lipid-based paleothermometry for applications in polar oceans

CITATION: Fietz, S., Ho, S. L. & Huguet, C. 2020. Archaeal membrane lipid-based paleothermometry for applications in polar oceans. Oceanography, 33(2):104–114, doi:10.5670/oceanog.2020.207.The original publication is available at https://tos.orgTo establish whether ongoing climate change is outside the range of natural variability and a result of anthropogenic inputs, it is essential to reconstruct past oceanic and atmospheric temperatures for comparison with the modern world. Reconstructing past temperatures is a complex endeavor that employs indirect proxy indicators. Over the past two decades, promising paleothermometers have been developed that use isoprenoidal glycerol dialkyl glycerol tetraethers (isoGDGTs) from the membrane lipids of archaea preserved in marine sediments. These proxies are based on the observed relationship between lipid structure and temperature. As with all proxy indicators, observed relationships are often complex. Here, we focus on the application of isoGDGT paleotemperature proxies in the polar oceans, critical components of the global climate system. We discuss the application of and caveats regarding these archaeal membrane lipid-derived proxies and make recommendations to improve isoGDGT-derived polar ocean temperature reconstructions. We also review initial successes using hydroxylated (OH) isoGDGTs proxies in cold Arctic and Southern Ocean regions and recommend that multi-proxy approaches, including both hydroxylated and non-hydroxylated isoGDGTs, be used to contribute to the robustness of paleotemperature reconstructions.Publisher's versio

Introducing Geosciences in a blended Education Master degree

[EN] The aim of the project was to introduce the subject of geosciences to a group of teachers without previous knowledge of the subject. Since the students of module presented here work full time, the master was designed in a blended format. While all students had completed their university education, none had done any geoscience studies/courses before making the starting level basic for the whole course. Contents and activities were carefully selected to provide a good introduction to geosciences giving the students the basic concepts and letting them apply them in a problem based strategy. Students reported that besides the blended nature of the course collaborative learning was necessary and key to their learning process. They also reported the contents of the course to be clear, organized sufficient and interesting. We view the module as a success since all students reported enjoying the module and building novel knowledge in the field of geosciences. Additionally since the students are in turn teachers we were very happy to learn some of them will implement geosciences in their activities in the future.http://ocs.editorial.upv.es/index.php/HEAD/HEAD18Huguet, C.; Francisco Blanco-Quintero, I.; Henao Mejía, MC.; Moreno Vela, FJ.; Chimbí Sanchez, LA. (2018). Introducing Geosciences in a blended Education Master degree. Editorial Universitat Politècnica de València. 107-116. https://doi.org/10.4995/HEAD18.2018.7905OCS10711

Use of emerging technologies in flipped classes

[EN] The need for this innovation stems from the constraints of teaching an applied science course to a large cohort of approximately 500 students which makes it impossible to include practical activities. This was compounded by the fact that the course had students with different levels of science knowledge. The aim of our pedagogic innovation was two-fold: to make the basic concepts more understandable for a broad audience of non-science major students; and to maintain a level of difficulty and rigour sufficient to challenge and provide a sound basis for students from the Geosciences undergraduate program. We used a flipped classroom strategy supported by the use of information and communication technologies. Material was provided online before the class so students could aquire basic concepts and identify gaps in their knowledge, and in the classroom the concepts were applied in group activities. Additionally we used the online quiz tool Socrative for students to self-assess their learning. This work was supported by post-class follow-up activities. As a result we observed a substantial increased in student motivation and engagement in their learning process and greater interaction between students and between students and teachers. Furthermore there was an improvement of overall performance with fever students failing the courseHuguet, C.; Pearse, J.; Noè, LF.; Castillo Ruiz, N.; Valencia, D.; Jimenez Heredia, A.; Patiño Avedaño, MA. (2017). Use of emerging technologies in flipped classes. En Proceedings of the 3rd International Conference on Higher Education Advances. Editorial Universitat Politècnica de València. 891-898. https://doi.org/10.4995/HEAD17.2017.5454OCS89189

Appraising GDGT-based seawater temperature indices in the Southern Ocean

A robust understanding of past oceanographic variability in the Southern Ocean is important because of its role in modulating global climate change. Here, we analyzed the distributions of isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs), both non-hydroxylated and the more recently discovered hydroxylated ones, in a well studied 500 kyr sediment record (core PS2489-2) from the Atlantic sector of the Southern Ocean and reconstructed past sea surface temperature. Given the uncertainty in the GDGT temperature indices, we appraised existing calibrations by comparing them with other temperature proxies and cold-water mass indicators determined from the same core. None of the existing calibrations afforded temporal trends and/or absolute values consistent with other better constrained temperature proxies. Using an extended compilation from a global core top hydroxylated GDGT data set, we examined if the disagreement might stem from the calibration data set and the definition of the GDGT indices. Among the new GDGT indices tested, the OHC index (an extended TEX86 index modified similarly to the UK37 index) and OHL (including a log function similar to TEX86L) showed temporal variability that was the most consistent with other proxies. However, they also gave unrealistic sub-zero glacial temperature values, which may have been caused by a biased calibration due to the small calibration data set, and/or a shift in production or export depth of GDGTs during glacial stages which, in turn, result in a GDGT-temperature relationship different from that during the interglacial stages

Cav-1 Protein Levels in Serum and Infarcted Brain Correlate with Hemorrhagic Volume in a Mouse Model of Thromboembolic Stroke, Independently of rt-PA Administration.

Thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA) is currently the only FDA-approved drug for acute ischemic stroke. However, its administration is still limited due to the associated increased risk of hemorrhagic transformation (HT). rt-PA may exacerbate blood-brain barrier (BBB) injury by several mechanisms that have not been fully elucidated. Caveolin-1 (Cav-1), a major structural protein of caveolae, has been linked to the endothelial barrier function. The effects of rt-PA on Cav-1 expression remain largely unknown. Here, Cav-1 protein expression after ischemic conditions, with or without rt-PA administration, was analyzed in a murine thromboembolic middle cerebral artery occlusion (MCAO) and in brain microvascular endothelial bEnd.3 cells subjected to oxygen/glucose deprivation (OGD). Our results show that Cav-1 is overexpressed in endothelial cells of infarcted area and in bEnd.3 cell line after ischemia but there is disagreement regarding rt-PA effects on Cav-1 expression between both experimental models. Delayed rt-PA administration significantly reduced Cav-1 total levels from 24 to 72 h after reoxygenation and increased pCav-1/Cav-1 at 72 h in the bEnd.3 cells while it did not modify Cav-1 immunoreactivity in the infarcted area at 24 h post-MCAO. Importantly, tissue Cav-1 positively correlated with Cav-1 serum levels at 24 h post-MCAO and negatively correlated with the volume of hemorrhage after infarction, the latter supporting a protective role of Cav-1 in cerebral ischemia. In addition, the negative association between baseline serum Cav-1 levels and hemorrhagic volume points to a potential usefulness of baseline serum Cav-1 levels to predict hemorrhagic volume, independently of rt-PA administration.This work was supported by grants from Instituto de Salud Carlos III and co-fnanced by the European Development Regional Fund “A Way to Achieve Europe” Health Strategic Action Program PI13/02258 and PI17/02123 (MC), PI20/00535 (IL), and Spanish Stroke Research Network RETICS RD12/0014/0010 (MC), and RD16/0019/0003 (JS), RD16/0019/0004 (MC), and RD16/0019/0009 (IL); from Regional Madrid Government B2017/BMD- 3688 (IL); from Spanish Ministry of Science and Innovation PID2019-106581RBI00 (MAM); from Leducq Foundation for Cardiovascular Research TNE-19CVD01 (MAM); and from Fundación La Caixa HR17_00527 (MAM). P. Comajoan was a recipient of a predoctoral fellowship from the University of Girona (IF-UdG 2015).S

Coherent millennial-scale patterns in Uk'37 and TEX86H temperature records during the penultimate interglacial-to-glacial cycle in the western Mediterranean

The TEX86H temperature proxy is a relatively new proxy based on crenarchaeotal lipids and has rarely been applied together with other temperature proxies. In this study, we applied the TEX86H on a sediment core from the Alboran Sea (western Mediterranean, core ODP-977A) covering the penultimate climate cycle, that is, from 244 to 130 ka, and compared this with previously published sea surface temperatures derived from the U37k' of alkenones of haptophyta and Mg/Ca records of planktonic foraminifera. The TEX86H temperature record shows remarkably similar stadial-interstadial patterns and abrupt temperature changes to those observed with the U37k' palaeothermometer. Absolute TEX86H temperature estimates are generally higher than those of U37k', though this difference (<3°C in 81% of the data points) is mainly within the temperature calibration error for both proxies, suggesting that crenarchaeota and haptophyta experienced similar temperature variations. During occasional events (<5% of the analyzed time span), however, the TEX86H exhibits considerably higher absolute temperature estimates than the U37k'. Comparison with Mg/Ca records of planktonic foraminifera as well as other Mediterranean TEX86 and U37k' records suggests that part of this divergence may be attributed to seasonal differences, that is, with TEX86H reflecting mainly the warm summer season while U37k' would show annual mean. Biases in the global calibration of both proxies or specific biases in the Mediterranean are an alternative, though less likely, explanation. Despite differences between absolute TEX86H and U37k' temperatures, the correlation between the two proxies (r2 = 0.59, 95% significance) provides support for the occurrence of abrupt temperature variations in the western Mediterranean during the penultimate interglacial-to-glacial cycle

A study of the TEX86 paleothermometer in the water column and sediments of the Santa Barbara Basin, California

Particulate organic matter collected during a 2-year period, as part of an ongoing sediment trap study, and a high-resolution sediment record from 1850 to 1987 A.D. from the Santa Barbara Basin were analyzed for TEX86, a temperature proxy based on marine crenarchaeotal membrane lipids. Highest fluxes of crenarchaeotal lipids in the water column were found in May-June 1996 and from October 1996 to January 1997 and, in general, showed a good correlation with mass fluxes. TEX86 reconstructed temperatures from the sediment trap series ranged from 8 to 11°C and were usually substantially lower than sea surface temperatures (SST), indicating that unlike in previous studies, the TEX86 corresponds to subsurface temperatures, likely between 100 and 150 m. TEX86 temperature variations observed in trap samples were not coupled to changes in SST or deep-water temperatures and only to some degree with crenarchaeotal lipid fluxes. This suggests that a complex combination of different depth origins and seasonal growth periods of Crenarchaeota contributed to the variations in TEX86 signal during the annual cycle. TEX86 temperatures in the two sediment cores studied (8-13°C) were also substantially lower than those of instrumental SST records (14-17.5°C) confirming that TEX86 records a subsurface temperature signal in the Santa Barbara Basin. This result highlights the importance of performing calibration studies using sediment traps and core tops before applying the TEX86 temperature proxy in a given study area

Bacterial dominance in subseafloor sediments characterized by methane hydrates

The degradation of organic carbon in subseafloor sediments on continental margins contributes to the largest reservoir of methane on Earth. Sediments in the Andaman Sea are composed of ~ 1% marine-derived organic carbon and biogenic methane is present. Our objective was to determine microbial abundance and diversity in sediments that transition the gas hydrate occurrence zone (GHOZ) in the Andaman Sea. Microscopic cell enumeration revealed that most sediment layers harbored relatively low microbial abundance (10³–10⁵ cells cm⁻³). Archaea were never detected despite the use of both DNA- and lipid-based methods. Statistical analysis of terminal restriction fragment length polymorphisms revealed distinct microbial communities from above, within, and below the GHOZ, and GHOZ samples were correlated with a decrease in organic carbon. Primer-tagged pyrosequences of bacterial 16S rRNA genes showed that members of the phylum Firmicutes are predominant in all zones. Compared with other seafloor settings that contain biogenic methane, this deep subseafloor habitat has a unique microbial community and the low cell abundance detected can help to refine global subseafloor microbial abundance.Keywords: Andaman Sea, molecular sequence data, geologic sediments/chemistry/microbiology, pyrosequencing, lipidsKeywords: Andaman Sea, molecular sequence data, geologic sediments/chemistry/microbiology, pyrosequencing, lipid