The Language of Mechanical Support in Children: Is It ‘Sticking’, ‘Hanging’, or Simply ‘On’?

Research has found that children begin to differentiate in the terms they use to encode support. In English, BE on, the Basic Locative Construction (Levinson & Wilkins, 2006; “put on” in dynamic events) tends to encode support-from-below (e.g., cup on table), whereas lexical support verbs (e.g., hang, stick, tape, glue, etc.) tend to encode mechanical support. We see this differentiation in semantic space by six years of age (Johannes et al., 2016). Although this differentiation occurs, we can still use BE on to encode all types of support, just as we can use a variety of lexical verbs (e.g., the picture is on/put on the wall, the picture is hanging on the wall, the picture is stuck to the wall, the picture is taped to the wall), In this study we ask several questions: 1) do four-year-olds use more lexical verbs to describe dynamic events compared to previous studies (Johannes et al., 2016; Landau et al., 2017) that use static stimuli, 2) does visibility of the support mechanism play a role in the lexical support verbs used and 3) do participants show a bias to encode specific aspects of the spatial configuration over another by using one class of verbs more, specifically do they encode the resulting spatial configuration (use Verbs of Putting in a Spatial configuration more; “hang”) or the manner of attachment (use Verbs of Attaching more; “stick, tape, clip”). The results suggest that four-year-olds use lexical verbs more than previous studies, suggesting that dynamic events elicit more lexical verbs compared to static stimuli. Further, we found that visibility does impact participants’ verbs use, and that participants have a linguistic bias when describing mechanical support events. Our results have implications for children’s knowledge of support mechanisms and how children reason about physical support events

Single-qubit lasing and cooling at the Rabi frequency

For a superconducting qubit driven to perform Rabi oscillations and coupled to a slow electromagnetic or nano-mechanical oscillator we describe previously unexplored quantum optics effects. When the Rabi frequency is tuned to resonance with the oscillator the latter can be driven far from equilibrium. Blue detuned driving leads to a population inversion in the qubit and a bi-stability with lasing behavior of the oscillator; for red detuning the qubit cools the oscillator. This behavior persists at the symmetry point where the qubit-oscillator coupling is quadratic and decoherence effects are minimized. There the system realizes a "single-atom-two-photon laser".Comment: Replaced with final published version, fig. 2 compresse

Comparing observed and modelled growth of larval herring (Clupea harengus): Testing individual-based model parameterisations

Experiments that directly test larval fish individual-based model (IBM) growth predictions are uncommon since it is difficult to simultaneously measure all relevant metabolic and behavioural attributes. We compared observed and modelled somatic growth of larval herring (Clupea harengus) in short-term (50 degree-day) laboratory trials conducted at 7 and 13°C in which larvae were either unfed or fed ad libitum on different prey sizes (~100 to 550 μm copepods, Acartia tonsa). The larval specific growth rate (SGR, % DW d-1) was generally overestimated by the model, especially for larvae foraging on large prey items. Model parameterisations were adjusted to explore the effect of 1) temporal variability in foraging of individuals, and 2) reduced assimilation efficiency due to rapid gut evacuation at high feeding rates. With these adjustments, the model described larval growth well across temperatures, prey sizes, and larval sizes. Although the experiments performed verified the growth model, variability in growth and foraging behaviour among larvae shows that it is necessary to measure both the physiology and feeding behaviour of the same individual. This is a challenge for experimentalists but will ultimately yield the most valuable data to adequately model environmental impacts on the survival and growth of marine fish early life stages. Comparación entre crecimiento observado y predicho de larvas de arenque (Clupea harengus): analizando parametrizaciones de modelos basados en individuos. – Los experimentos que analizan directamente las predicciones de crecimiento generadas por modelos basados en individuos (IBM) son poco comunes puesto que resulta difícil medir simultáneamente todos los atributos metabólicos y conductuales. En este estudio, comparamos el crecimiento somático observado y el estimado a partir de modelos de larvas de arenque (Clupea harengus) en experimentos de laboratorio a corto plazo (50 grados-día) a 7 y 13°en los que las larvas fueron mantenidas en condiciones de ayuno o recibieron alimentación ad libitum con diferentes tamaños de presa (copépodos, Acartia tonsa, de aproximadamente 100 a 500 μm). Las estimas de tasa específica de crecimiento (SGR, % de peso seco por día) fueron, en general, sobreestimadas por el modelo, especialmente para larvas que se alimentaron con presas grandes. estimas del modelo se ajustaron a dos escenarios para explorar el efecto de 1) variabilidad temporal en la alimentación de las larvas, y 2) disminución en la eficiencia de asimilación debida una rápida evacuación del tubo digestivo a tasas de alimentación altas. Con estos ajustes, el modelo describió bien el crecimiento larvario para temperaturas, tamaños de presa y edades de las larvas, indicando que las parametrizaciones metabólicas son robustas. Aunque los experimentos llevados a cabo con grupos de larvas verificaron los modelos de crecimiento, la variabilidad en el crecimiento y conducta de alimentación entre larvas sometidas a las mismas condiciones ambientales ponen de relieve la necesidad de que las medidas fisiológicas y de conducta vayan emparejadas y sean tomadas a nivel individual. Esto representa un reto para los experimentalistas, pero a largo plazo generará datos valiosos para los modeladores encargados de simular efectos ambientales sobre las tasas vitales de estadíos tempranos de desarrollo de peces marinos

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2 and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply considerably fuels bacterial anaerobic ammonium oxidation – a major loss process for fixed nitrogen in the ocean. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a downregulation of ammonium excretion. Here we show that exposure to OMZ conditions can result in strong depression of respiration and ammonium excretion in calanoid copepods and euphausiids from the Eastern Tropical North Atlantic and the Eastern Tropical South Pacific. These physiological responses need to be taken into account when estimating DVM-mediated fluxes of carbon and nitrogen into OMZs

3. Wochenbericht POS532

18/2/2019-24/2/201

Welche Rolle spielen Konferenzen in der Wissenschaft? Antworten aus der Perspektive von Nachwuchswissenschaftler*innen

Kaum eine andere Institution der Wissenschaft verbindet so sehr Erwartungssicherheit mit Ergebnisoffenheit wie die wissenschaftliche Konferenz. Das hohe Maß an Ergebnisoffenheit wirft die Frage auf, welche Folgen die Teilnahme an Konferenzen für Wissenschaftler*innen und die Wissenschaft hat. Der Beitrag stellt empirische Ergebnisse eines Dissertationsprojektes vor, das sich dieser Frage aus der Perspektive von Nachwuchswissenschaftler*innen gewidmet hat. Der Beitrag ist folgendermaßen aufgebaut: Zunächst wird der Forschungsstand zum Phänomen der Konferenz aus Sicht der Wissenschaftsforschung skizziert und Daten zu Konferenzen in Deutschland präsentiert. Das darauffolgende Kapitel widmet sich der Praxis des \u27Konferierens\u27 in der Wissenschaft, wobei ein soziologischer Zugang gewählt wird. Einer kurzen Zusammenfassung der verwendeten Methoden folgt die Darstellung der zentralen Ergebnisse. Abschließend werden Implikationen für die Wissenschaftsforschung aufgezeigt. (DIPF/Orig.

Pelagic community responses to changes in N:P stoichiometry in the Eastern Tropical Atlantic and Pacific

Recent studies indicate that the tropical ocean is losing oxygen. This becomes crucial in regions adjacent to eastern boundary currents, as the productivity of these systems is already accompanied by oxygen minimum zones (OMZ) at depth below the photic zone. The extent of low oxygen water masses influences dissolved nutrient inventories, as oxygen-sensitive nitrogen (N) loss processes such as denitrification and anammox are enhanced and inorganic phosphorus is remobilized from sediments, resulting in low N:P of upwelled waters, especially in the East Pacific. The present study aimed to investigate the impact of changing N and P supply on the pelagic primary producers and consumers in the photic zone. To achieve this, nutrient manipulation experiments were conducted in the eastern tropical Pacific and Atlantic Ocean using a newly designed shipboard mesocosm setup. Results demonstrated that in these regions, where N:P is generally below the canonical Redfield ratio of 16, inorganic N is the key control of bulk productivity regardless of the amount of P added, especially of bloom-forming diatom species and ciliate consumers (chapter I and II). However, the response of individual species and pools of organic matter was found to be more complex. For example, Phaeocystis globosa and Heterosigma sp. clearly benefitted from high P-levels (chapter I). Both algal groups are considered of inferior quality to mesozooplankton consumers compared to diatom-dominated assemblages. The observation that the relative content of unsaturated fatty acids in the particulate matter was positively related to diatom biomass (chapter I) is a second clue that decreasing N flux to the surface ocean impacts food web productivity. However, the RNA/DNA ratio, as a proxy for nutritional condition, did not change in the copepod Undinula vulgaris when fed on the manipulated mesocosm community over a period of three days (chapter II). The results of the nutrient manipulation experiments off Peru and West Africa were surprisingly similar, despite the fact that the North Atlantic features excess N at depth due to N2-fixation and the lack of suboxic conditions that would promote N-loss processes. Furthermore, pigments characteristic for cyanobacteria indicated that diazotrophs were increasing in those mesocosms that had received a higher initial N load (chapter I and II), which contradicts the common understanding that diazotrophs would benefit from excess P. In addition, we observed that the N:P excretion ratio of copepods (U. vulgaris) feeding on the manipulated mesocosm assemblage was influenced by the N:P of bulk particulate organic matter (PON:POP), which in turn responded directly to the manipulation ratios (chapter II). In order to survey the natural variability in N and P excretion rates in the Eastern Tropical North Atlantic, measurements were conducted in shipboard incubations at several stations on three epipelagic copepod species (chapter III). Within species, excretion N:P was positively related to PON:POP at the respective station; however, the low number of stations sampled and the variability of PON:POP within the upper 150 m hampered the establishment of a functional relationship. The N:P excretion ratio was consistently higher in the carnivorous Euchaeta marina compared to the omnivorous U. vulgaris and Scolecithrix danae. This can be attributed to the rather rigid N:P stoichiometry of zooplanktonic prey items of E. marina in contrast to the unicellular food items of the other two species (such as diatoms, dinoflagellates and heterotrophic protists) with more variable N:P. A further question addressed in this study was to what extent atmospheric N sources (N2-fixation and dust) are contributing to secondary production in the Eastern Tropical North Atlantic, and how this contribution is related to the vertical flux of dissolved inorganic nitrogen (chapter IV). We used zooplankton stable nitrogen isotopes (15N) to estimate the relative contribution of atmospheric N sources and found that it ranged from less than 20% off the West African coast to 60% in the open ocean (Guinea Dome region), and was positively related to the depth of the nitracline

Dissolved N:P ratio changes in the eastern tropical North Atlantic: effect on phytoplankton growth and community structure

Previous bioassays conducted in the oligotrophic Atlantic Ocean identified availability of inorganic nitrogen (N) as the proximate limiting nutrient control of primary production, but additionally displayed a synergistic growth effect of combined N and phosphorus (P) addition. To classify conditions of nutrient limitation of coastal phytoplankton in the tropical ocean, we performed an 11 d nutrient-enrichment experiment with a natural phytoplankton community from shelf waters off northwest Africa in shipboard mesocosms. We used pigment and gene fingerprinting in combination with flow cytometry for classification and quantification of the taxon-specific photoautotrophic response to differences in nutrient supply. The developing primary bloom was dominated by diatoms and was significantly higher in the treatments receiving initial N addition. The combined supply of N and P did not induce a further increase in phytoplankton abundance compared to high N addition alone. A secondary bloom during the course of the experiment again displayed higher primary producer standing stock in the N-fertilized treatments. Bacterial abundance correlated positively with phytoplankton biomass. Dominance of the photoautotrophic assemblage by N-limited diatoms in conjunction with a probable absence of any P-limited phytoplankton species prevented an additive effect of combined N and P addition on total phytoplankton biomass. Furthermore, after nutrient exhaustion, dinitrogen (N-2)-fixing cyanobacteria succeeded the bloom-forming diatoms. Shelf waters in the tropical eastern Atlantic may thus support growth of diazotrophic cyanobacteria such as Trichodesmium sp. subsequent to upwelling pulses