There and back again : The neural basis of migration in the Bogong moth

The Bogong moth (Agrotis infusa) is a small, night-active Australian moth that has a remarkable lifestyle. Afterhatching from its pupa in spring, it migrates over 1000 km to the Australian Alps, where it spends the summer incool alpine caves. In the beginning of autumn, the moths emerge from the caves and fly back to their breedinggrounds, where they mate, lay eggs, and die. The following year, a new generation of moths repeats the samejourney to the mountains.Migration is a difficult and dangerous task. If the moths get lost on the way, they will not arrive at the caves in timeand will instead perish in the hot Australian summer. It is therefore crucial that they are efficient and reliablenavigators. However, the brains of these moths are tiny – only 3 mm in diameter. How can such a small braincompute the trajectory of this extraordinary migration?In this thesis, I investigated the neural basis of navigation and migration in the Bogong moth. I began by describingthe Bogong moth brain in detail (Paper I). In insects, neurons in a brain region known as the central complex processspatial information and provide the spatial context for behavioural decisions. The central complex of the Bogongmoth is well developed and can be expected to have the same function as in other insects. From previous studies,we know that brain regions that are of special importance for an animal tend to be bigger. I therefore compared thevolume of several higher processing neuropils, including the central complex, across several moth species (PaperII), including both migrants and non-migrants. I found that that the relative volumes of the central complex acrossspecies were very similar. In fact, the central complex scaled hypo-isometrically, suggesting that the neural networksin this brain region are so fundamentally important that even the smallest moths cannot afford to reduce them further.Therefore, instead of being reflected in the overall volume of the central complex, migratory behaviour may bereflected in the response properties of individual neurons in this brain region. Knowing that the Bogong moth canchoose a migratory heading based on the starry sky alone, I recorded from neurons in the central brain whilepresenting the moth with a rotating starry sky (Paper III). I found several neurons that consistently responded to thisstimulus. Some of these neurons had branches in the optic lobes, the central complex or the lateral complex, whichare all associated with visual compass processing. Thus, these neuropils provide a suitable substrate for processingcompass cues during the moths’ nocturnal migration. Finally, I investigated how a compass signal in the centralcomplex is transmitted to downstream motor centres that coordinate wing and leg movement. To this end, I built acomputational model of a proposed steering network (Paper IV). I showed that this network can theoretically steerbased on input from olfaction as well as vision, providing a putative connection between the compass system in thecentral complex and thoracic motor centres. Taken together, these results have not only shed light on the neuralbasis of migration in the Bogong moth, but also on neural processing in the insect central complex and lateralaccessory lobes in general. In the future, combining these results with insights from other insects may lead to acomplete understanding of the neural basis of migration, from the sensory inputs to the behavioural output

Financial constraints, capital structure and dividend policy: Evidence from Jordan

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The economic reforms in Jordan during the last two decades have highlighted and promoted the role that non-financial firms play within the Jordanian economy. The ability of firms to play this role is in major part determined by the structure of the financial system in which they operate, and in particular whether this financial system is able to make capital available efficiently to those firms that need it. Whether this is the case can be investigated by analysing the impact of firm characteristics on some of the most important financial decisions taken by these firms, and how these decisions are influenced by the presence of market imperfections. The thesis examines the relation between the financing and investment decisions, where the effect of financial constraints on the firm’s investment decision is investigated. In particular, this thesis focuses on how financial constraints affect different firms by investigating the extent to which the reliance on internal cash flow is affected by firm characteristics such as size, age, dividend payout ratio, and market listing. We find that Jordanian firms are financially constrained, but that these constraints do not appear to be related to firm characteristics. Further, results show that Jordanian firms use debt rather than equity to finance their investment. The second empirical chapter focuses on the main determinants of firms’ capital structure. Here the results show that Jordanian firms follow the pecking order theory, where profitability and liquidity have a negative impact on the level of debt. Size and market to book value have a positive impact, supporting the view that there are significant constraints on debt financing since indicators of the financial health of the firms affect their capital structure ratio. There is also evidence that ownership structure affects the firm’s access to debt. The final empirical chapter examines the impact of firm characteristics on dividend policy, and shows that profitability and market to book value have a positive impact on dividend policy, implying that firms with better access to capital or credit pay dividends. This implies that firms retain earnings in order to ensure that they have sufficient capital to invest, confirming the initial result that Jordanian firms are financially constrained. There is also evidence of the impact of ownership structure, consistent with the predictions of agency cost theory, while institutional investors appear to follow the prudent-man restrictions, being positively associated with firms that pay dividends. This thesis confirms the presence of market imperfections that have a significant influence on the financial decisions taken by Jordanian firms. The consistent evidence of the importance of retained earnings shows that these firms face substantial constraints in terms of their access to external funds, despite the reforms to the Jordanian financial system over the last two decades.This study is funded by Mutah University, Jordan

Digital Amnesia: The Aftermath of a Screenshot

The photo impairment effect is the finding that memory for photographed information is worse than for viewed information. Recent research has extended this finding to stimuli that are screenshot on a phone or computer (Lurie et al., submitted). One potential explanation for the impairment is cognitive offloading, which is a reliance on an external memory store for information (Henkel, 2014; Lurie & Westerman, 2021; Lurie et al., submitted). Four experiments were conducted to examine the feasibility of the offloading account by investigating potential benefits of taking screenshots as compared with viewing pieces of art, as suggested by previous research. The results suggest that the act of screenshotting produces memory costs (average d = 1.35) without the expected benefits for source memory, subsequently learned information, or performance on a cognitive task compared with viewing. These collective findings do not support a cognitive offloading explanation.https://orb.binghamton.edu/research_days_posters_2024/1073/thumbnail.jp

Substitutionsmuster in und über Polymerketten: Neue Ansätze für Carboxymethylcellulose

In this work, the so-called "oligomer analysis" for the determination of the substitution pattern was applied on carboxymethyl cellulose (CMC). This strategy comprises a random degradation of the polymer to oligomeric sequences (by partial hydrolysis or methanolysis) and the quantitative mass spectrometric (MS) analysis of the substituent distribution within a distinct DP after appropriate sample preparation. Monomer analysis as reference was performed by capillary electrophoresis (CE-UV). Critical points in oligomer analysis are the MS-measurement and the partial degradation. Especially in ESI-Ion Trap-MS, the mass difference, the polarity of the analytes and their number of CM-groups influence the ionization and the ion yield. To prepare analytes chemically as uniform as possible and thus eliminate discriminating effects, the free hydroxyl groups of oligomeric methyl glucosides/methyl esters obtained by partial methanolysis were subsequently acylated with different. It could be concluded that a similarity of the acylate to the methoxycarbonyl-methyl-group in polarity and sodium complexation ability was more important than a similarity in mass. Methoxyacetate showed the best results of the tested agents. Hydrolysis and methanolysis were investigated with regard to their randomness and kinetics. Depending on DS and substitution pattern, CMC can form aggregates in water, which might cause bias in the accessibility of the cellulose molecules. The rate of hydrolysis was further expected to be influcenced due to steric, ionic and neighbour-group effects of the CM-groups in the AGU. In the beginning of hydrolysis, a release order of un ~ 3 > 3,6 > 6 > 2,3,6 ~ 2,3 > 2,6 > 2 (-O-substituted CM-glucose derivatives) was observed. Methanolysis starts as a heterogeneous process. The reaction course thus showed characteristics of a peeling process, i.e. pseudo-zero order in the beginning and fastened in the further course.In dieser Arbeit wurde die sogenannte "Oligomeranalytik" zur Bestimmung des Substitutionsmusters auf Carboxymethylcellulose (CMC) angewendet. Diese Strategie beinhaltet den Abbau des Polymers (mittels partieller Hydrolyse oder Methanolyse) in oligomere Sequenzen und die quantitative massenspektrometrische (MS) Analyse der Substituentenverteilung innerhalb eines bestimmten DP nach geeigneter Probenvorbereitung. Als Referenz wurde Monomeranalytik mittels Kapillarelectrophorese (CE-UV) durchgeführt. Kritische Punkte bei der Oligomeranalytik sind die MS-Messung und der partielle Abbau. Besonders bei ESI-Ion Trap-MS beeinflussen die Massendifferenz, die Polarität der Analyten und deren Anzahl an CM-Gruppen Ionisierung und Ionenausbeute. Um chemisch möglichst einheitliche Analyten herzustellen und damit diskriminierende Effekte zu vermindern, wurden die freien Hydroxylgruppen der oligomeren Methylglucoside/ Methylester, enstanden nach partieller Methanolyse, verschieden acyliert. Es wurde festgestellt, dass eine Ähnlichkeit der Acylgruppe zur Methoxycarbonyl-methylgruppe in der Polarität und Natriumkomplexierungsfähigkeit wichtiger ist als eine änhliche Masse. Methoxyacetate zeigten die besten Ergebnisse der getesteten Acylierungsmittel. Hydrolyse und Methanolyse wurden auf die Zufälligkeit des Abbaus und die Kinetik untersucht. Abhängig von DS und Substitutionsmuster kann CMC in Wasser Aggregate bilden, die zu einer unterschiedlichen Zugänglichkeit der Cellulosemoleküle führen können. Ferner kann die Hydrolyserate von den CM-Gruppen innerhalb der AGU aufgrund sterischer, ionischer und Nachbargruppen-Effekte beeinflusst werden. Zu Beginn der Hydrolyse wird eine Reihenfolge der Freisetzung von un ~ 3 > 3,6 > 6 > 2,3,6 ~ 2,3 > 2,6 > 2 (-O-CM-Glucosederivaten) beobachtet. Methanolyse startet als heterogener Prozess. Der Reaktionsverlauf zeigt Eigenschaften eines Peeling-Prozesses, d.h., er verläuft pseudo-Nullter Ordnung am Anfang und beschleunigt im weiteren Verlauf

Wind tunnel flutter tests of a strut-braced high aspect ratio wing

International audienceIncreasing the wing aspect ratio is one way to improve aircraft aerodynamic efficiency. This reduces the induced drag term but, at the same time, produces an increment of the wing loads, hence an increase of the structural weight. One design solution to reduce the wing root bending moment, which is the main driver of the weight of the wing, is the addition of a strut. This work deals with the experimental identification of the flutter behavior of an ultra-high aspect ratio (19) strut-braced wing in a wind tunnel. The inherent non-linear behavior of such a structure that has two different effects on the wing when loaded in compression and in tension is coupled with large deformations due to its extreme flexibility. From here derives the extreme importance of experimental tests to understand how different parameters of such a design can impact its aeroelastic behavior

weego: Una red social turística

La tecnología avanza velozmente y todos los aspectos de nuestra vida se ven afectados por los avances tecnológicos. En la actualidad es común que al realizar viajes utilicemos dispositivos GPS (Global Positioning System), que no sólo nos permite consultarlo a modo de mapa sino que además nos da indicaciones acerca de qué ruta utilizar para llegar a un sitio de la manera más rápida (en tiempo), más corta (en distancia) o incluso más económica. La evolución del hardware se ve estrechamente ligada a la evolución del software (y viceversa). Con la aparición de las primeras computadoras se desarrollaron los primeros programas para aplicaciones específicas. Luego, con la evolución de las computadoras y la conectividad de las mismas, fueron surgiendo los sistemas operativos y las redes de computadoras, que junto con el uso masivo de las computadoras y el auge de internet, permitieron el surgimiento de los llamados medios sociales, como blogs, wikis y redes sociales (Facebook, Twitter, etc.). El objetivo de esta tesina es el desarrollo de una red social orientada al turismo utilizando herramientas open source, que permita a un conjunto de personas interactuar compartiendo lugares y eventos, que pueda ser utilizada con tecnologías web y móviles.Facultad de Informátic

weego: Una red social turística

La tecnología avanza velozmente y todos los aspectos de nuestra vida se ven afectados por los avances tecnológicos. En la actualidad es común que al realizar viajes utilicemos dispositivos GPS (Global Positioning System), que no sólo nos permite consultarlo a modo de mapa sino que además nos da indicaciones acerca de qué ruta utilizar para llegar a un sitio de la manera más rápida (en tiempo), más corta (en distancia) o incluso más económica. La evolución del hardware se ve estrechamente ligada a la evolución del software (y viceversa). Con la aparición de las primeras computadoras se desarrollaron los primeros programas para aplicaciones específicas. Luego, con la evolución de las computadoras y la conectividad de las mismas, fueron surgiendo los sistemas operativos y las redes de computadoras, que junto con el uso masivo de las computadoras y el auge de internet, permitieron el surgimiento de los llamados medios sociales, como blogs, wikis y redes sociales (Facebook, Twitter, etc.). El objetivo de esta tesina es el desarrollo de una red social orientada al turismo utilizando herramientas open source, que permita a un conjunto de personas interactuar compartiendo lugares y eventos, que pueda ser utilizada con tecnologías web y móviles.Facultad de Informátic

weego: Una red social turística

La tecnología avanza velozmente y todos los aspectos de nuestra vida se ven afectados por los avances tecnológicos. En la actualidad es común que al realizar viajes utilicemos dispositivos GPS (Global Positioning System), que no sólo nos permite consultarlo a modo de mapa sino que además nos da indicaciones acerca de qué ruta utilizar para llegar a un sitio de la manera más rápida (en tiempo), más corta (en distancia) o incluso más económica. La evolución del hardware se ve estrechamente ligada a la evolución del software (y viceversa). Con la aparición de las primeras computadoras se desarrollaron los primeros programas para aplicaciones específicas. Luego, con la evolución de las computadoras y la conectividad de las mismas, fueron surgiendo los sistemas operativos y las redes de computadoras, que junto con el uso masivo de las computadoras y el auge de internet, permitieron el surgimiento de los llamados medios sociales, como blogs, wikis y redes sociales (Facebook, Twitter, etc.). El objetivo de esta tesina es el desarrollo de una red social orientada al turismo utilizando herramientas open source, que permita a un conjunto de personas interactuar compartiendo lugares y eventos, que pueda ser utilizada con tecnologías web y móviles.Facultad de Informátic