Methods in soil micromorphology : a technique for the preparation of large thin sections

Stiboka onderzoe

An integrated chemical and micromorphological investigation of humic substances in three podzolized soils of the Netherlands.

The humic substances in a 'Holt' leptic podzol, a 'Haar' humic podzol and a 'Veld' gleyic podzol from the Netherlands were analysed chemically and micromorphologically. The absorption spectra of Na-humates in visible light and infrared spectra were determined for the humic acids. The translocation and distribution of the principal humus compounds occurred by mechanical illuviation in the 'Holt' podzol, and by translocation in solution in the 'Haar' podzol and the 'Veld' podzol. The micromorphological images were closely correlated with the chemical composition of the humic substances. Illuviation cutans occurring in the B horizons of the 'Haar' podzol and the 'Veld' podzol appeared to consist mainly of fulvic acids. The dark humus micro-aggregates characteristic of the 'Haar' podzol and the Ap horizon of the 'Veld' podzol were composed mainly of bitumens, humins and humic acids of high molecular weight, while the brown micro-aggregates of the 'Holt' podzol and the lower horizons of the 'Veld' podzol consisted mainly of fulvic acids and humic acids of low molecular weight. The stability of micro-aggregates was correlated with their composition. (Abstract retrieved from CAB Abstracts by CABI’s permission

Differences in Strength & Power profiles between Road and Time Trial cyclists

Introduction Within the scientific literature there is little evidence available to provide practitioners with information on strength and power profiles of cyclists, resulting in a limited understanding of neuromuscular factors related to cycling performance. Information on the legs’ elastic energy utilisation, force-velocity and length-tension curves can inform training programs and aid in talent identification. Other sports where such information is more widely available have already successfully implemented this within preparation programmes (e.g. McBride et al., 1999). Methods A total of 44 cyclists were recruited for this project, of which 15 classified in a Novice category by having no racing experience at all (age 35.5 ± 11.4 yrs; height 177.4 ± 6.5 cm; mass 77.4 ± 9.3 kg; FTP 3.28 ± 0.47 W/kg), 14 in the Road racing category as they competed for at least the past year at British Cycling Category 2 level or higher and no experience in Time-Trial (TT) races (age 35.9 ± 12.7 yrs; height 179.1 ± 6.5 cm; mass 76.6 ± 9.0 kg; FTP 3.88 ± 0.49 W/kg), and 15 in the TT category as they considered TT racing as their main competitive aim, rode in dedicated TT positions and had recently produced a 10 or 25 mile personal best of 1) for all groups. This dominance was significantly less prominent in the TT group for flexion conditions (1.35 ± 0.18) compared to Road (1.56 ± 0.22; p = 0.031) and Novice (1.53 ± 0.19; p = 0.004) groups. Joint flexion torques showed non-significant trends; they were slightly higher in the knee and lower for the hip (1.43 & 2.08 Nm/kg respectively) in TT athletes compared to Road (1.35 & 2.14 Nm/kg) and Novices (1.36 & 2.22 Nm/kg) (p = 0.429 & 0.189). No differences were found for the angle at which peak torque occurred. The velocity effect on torque production was comparable between the groups. It decreased from its peak at 30 °/s, to 82 ± 11 % of that when tested at 270 °/s for knee flexion and to 61 ± 9 % for knee extension. Hip torque reduced to 66 ± 10 % and 79 ± 10 % for flexion and extension respectively, when tested at 210 °/s compared to 30 °/s condition. Discussion The CMJ data show that cyclists – both novice and competitive – perform poorly on vertical jumping (29 ± 6 cm) compared to strength trained (48.2 ± 2.8 cm) and even untrained individuals (33.7 ± 2.3 cm) (McBride et al., 1999). This is in line with previous research on endurance type athletes showing long-distance runners to perform inferiorly on jump tasks compared to an untrained population (27.8 ± 4.3 cm vs 37.3 ± 3.1 cm; Kubo et al., 2000). In contrast to the findings by Kubo et al. (2000), the tested competitive cyclists showed lower SJ/CMJ ratios compared to the untrained controls indicating a relatively large utilisation of elastic energy storage compared to muscular power in jump performance. Based on the dynamometry testing, it seems most plausible to suggest that the reduced hip flexion capacity in TT riders results from these muscles being disused during cycling due to the extreme hip flexion angles common in their riding positions. It could be suggested that an attempt is made to compensate for this loss in hip flexion capacity through increased knee flexors’ strength. An increased knee flexor torque in TT riders could also indicate a mechanically more effective pedalling technique on the bike, as previous literature has linked hamstring activity with increases in Index of Force Effectiveness on the bike (Bini et al., 2013). Greater separation between tested groups might have been masked due to variation in preferred bike setup within the groups, TT riders also training in road setups and novice cyclists having undergone minor adaptations through recreational cycling activities. Based on these results, it seems appropriate to advise strength training to be tailored to the type of competition a cyclist is aiming to perform on. TT riders should focus on knee flexor strength, while road cyclists could benefit from a more balanced approach between hip and knee strength. Currently ongoing research is investigating how these strength characteristics relate to determinants of cycling performance in order to further help optimising training protocols and talent identification strategies. References Bini RR, Hume P, Croft J, Kilding A. (2013) J Sci Cycl, 2(1), 11-24. Kubo K, Kanehisa H, Kawakami Y, Fukunaga T. (2000). EJAP, 81(3), 181-187. McBride JM, Triplett-McBride T, Davie H, Newton RU. (1999). J Biom, 32(10), 1021-1026. Cuk I, Markovic M, Nedeljkovic A, Ugarkovic D, Kukolj M, Jaric S. (2014). EJAP, 114(8), 1703-1714

Energy-dispersive X-ray analysis on thin sections and unimpregnated soil material.

A combination of scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXRA) was used in the study of soil materials. The investigation in situ of components in thin sections was used to estimate chemical elements with atomic numbers 11 upwards, from sodium on. EDXRA could detect chemical elements up to magnifications of X 10 000. The composition of amorphous and micro-crystalline materials cannot be estimated in thin sections by light microscopy but by this technique was clearly displayed. Composition of loose soil material can also be investigated. The material that could be studied by SEM-EDXRA did not need high polishing of the thin section, and the plastic used for impregnation of the soil material was not affected by the investigation.Identification of chemical elements in situ, high resolution of the topographic image and relatively short testing times for the elements make this combination of techniques useful for soil research. (Abstract retrieved from CAB Abstracts by CABI’s permission

Wavelength and energy-dispersive X-ray microanalysis with EMA and SEM-EDXRA on thin sections of soils.

Organic matter, minerals and iron-manganese nodules were studied in thin sections of soils with an electron microprobe analyzer (EMA) and a combination of a scanning electron microscope (SEM) and an energy-dispersive X-ray analyzer (EDXRA). Both instruments were used to estimate the presence and nature of chemical elements in two selected areas, one containing a combination of organic and mineral material and another inside an iron-manganese nodule. The detection of organic matter proved problematic. Of the light elements, N could not be detected with EMA and O was detected but was not specific to organic matter. EMA could not be used for C because of the C coating of the thin section. SEM-EDXRA only detected heavier elements. EMA produced somewhat better X-ray images of heavier elements, especially from an iron-manganese nodule. However, with organic material, SEM-EDXRA X-ray images were similar to or slightly better than EMA. An advantage of SEM-EDXRA over EMA is that the soil material can be analysed at various magnifications with a much higher limit, and point analysis can be made of loose material. For soil material, SEM-EDXRA was better as a routine instrument which solved most problems. EMA can be used as a complementary instrument. Other microanalytical techniques such as the ion microprobe mass analyzer (IMMA) were necessary to analyse light elements in organic material of soils. (Abstract retrieved from CAB Abstracts by CABI’s permission

Chemical element detection in thin sections of soils with the Laser Microprobe Mass Analyzer (LAMMA 500).

Components from thin sections of soils developed on weathered granite were analysed with the Laser Microprobe Mass Analyzer. Fragments of thin sections were mounted on sandwich grids, and perforated with the laser from the edges inwards (laser milling), using the laser light at grazing incidence. Laser-induced mass spectra of secondary titanium compounds and other constituents in the weathered granite were obtained in this manner. Positive and negative laser desorption mass spectra were recorded with such a speed and accuracy that in spite of the relatively large volume of analysed materials, minute changes in composition could be detected over very short distances. This allowed total chemical element analysis of spots in which titanium compounds concentrated during weathering, giving information on changes in purity of amorphous and semi-crystalline materials at such sites. Characteristic analysis possibilities of the Ion Microprobe Mass Analyzer (IMMA), Laser Microspectral Analyzer (LMA) and Laser Microprobe Mass Analyzer (LAMMA 500) are compared. (Abstract retrieved from CAB Abstracts by CABI’s permission

Physician gaze shifts in patient-physician interactions:functions, accounts and responses

ObjectivesPhysician gaze towards patients is fundamental for medical consultations. Physicians’ use of Electronic Health Records (EHR) affects their gaze towards patients, and may negatively influence this interaction. We aimed to study conversation patterns during gaze shifts of physicians from the patient towards the EHR.MethodsOutpatient consultations (N=8) were eye-tracked. Interactions around physician gaze shifts towards the computer were transcribed.ResultsWe found that physician gaze shifts have different interactional functions, e.g., introducing a topic switch or entering data into the EHR. Furthermore, physicians differ in how they account for their gaze shifts, i.e., both implicitly and explicitly. Third, patients vary in treating the gaze shift as an indication to continue their turn or not.ConclusionsOur results suggest that physician gaze shifts vary in function, in how physicians account for them, and in how they influence the conversation. Future research should take into account distinctions when relating gaze to patient outcomes.Practice implicationsPhysicians may be aware of the interactional context of their gaze behaviour. Patients respond differently to various types of gaze shifts. How physicians handle gaze shifts can therefore have different consequences for the interaction

Light and heavy element detection in thin sections of soils with the ion microprobe mass analyzer (IMMA).

Previous research with the scanning electron microscope (SEM)-energy dispersive X-ray analyzer (EDXRA) and the electron microprobe analyzer (EMA), showed that the detection of light elements in thin sections of soils was problematic or even impossible. Consequently initial experiments were performed with the ion microprobe mass analyzer (IMMA). These preliminary investigations were carried out on a piece of root material in soil (containing both light and heavy elements) which has a 'clayey' appearance and is known as a clayified root (Parfenova et al., 1964). The presence of heavier elements in this sample was investigated by SEM-EDXRA prior to IMMA analysis. The results with the ion microprobe mass analyzer showed that all chemical elements could be analyzed in the plant fragment. Also much higher elemental detection sensitivities were found with IMMA as compared to SEM-EDXRA and EMA. This even allowed ion imaging of trace elements. High-quality ion images of both light and heavy elements could be obtained in much shorter exposure times than with SEM-EDXRA and EMA techniques. Furthermore by analysis of fragmentation ('fingerprint') spectra additional information was obtained with respect to the chemical binding of the analyzed elements. Due to these preliminary results IMMA offers full possibilities for microchemical analysis in situ of all important elements in soil specimens. This technique considerably increases possibilities in soil micromorphology. (Abstract retrieved from CAB Abstracts by CABI’s permission

Inrichtings- en uitvoeringsaspecten van perceelsvergroting op lichte zavelgronden in het noordelijk klei mozaiekgebied

Voor de bestudering van aspecten van perceelsvergroting op lichte zavelgronden in het noordelijk klei mozaiekgebied is te Kloosterburen in de provincie Groningen een proef genomen waarbij met minimaal grondverzet de vergroting is gerealiseerd. Een team van onderzoekers, bestaande uit medewerkers van de LD, Stiboka, het IB en ICW, heeft onderzoek verricht aan verschillende aspecten. Het onderzoek is gericht geweest op de aard en omvang van oppervlakte-afvoer en de werking van zakputten (ICW); het tijdstip van bewerkbaarheid in het voorjaar, veranderingen van bodemfysische eigenschappen onder invloed van cultuurtechnische ingrepen en slempgevoeligheid (IB); profielbeschrijvingen, samenhang indringingsweerstanden en cultuurtechnische ingrepen (Stiboka); de werking van het ontwateringssysteem (afd. Onderzoek LD te Groningen); gewasreacties op verschraling en bodemverdichting (ICW) en de economische evaluatie (afd. Landbouw Economisch Onderzoek LD te Utrecht en Consulentschap Akkerbouw te Groningen). De bedoeling van het voorliggende rapport is, gebaseerd op de resultaten van dit proefveld, aangevuld met waarnemingen op andere objecten waar aspecten van uitvoering zijn bestudeerd, richtlijnen te formuleren voor het ontwerpen van het ontwateringsstelsel en het aangeven van mogelijkheden om niet gewenste neveneffecten van de uitvoering te voorkomen of te verbetere

Vijftig jaar monitoring en beheer van de Friese en Groninger kwelderwerken: 1960-2009

Dit WOt-werkdocument is een update van het kwelderboek uit 2001 en gaat ook over de bescherming door de kwelderwerken tegen de Allerheiligenvloed van 2006, over de Kaderrichtlijn Water en over de Sylt Conferentie van 2010. In 2007 verscheen in de WOT IN serie al een deel over Monitoring van kwelders in de Waddenzee, met beheermaatregelen voor alle kwelders (www.waddenzee.nl/Kwelders.1982.0.html). In de publicaties is ook aandacht voor beweiding, vegetatiekaarten, veroudering van de vegetatie, zeegras, grondwerk, ontwatering, en duurzaamheid van de rijshoutdammen