Deep Trajectory Research Articles

On the deep superstring spectrum

We propose a covariant method of constructing entire trajectories of physical states in superstring theory in the critical dimension. It is inspired by a recently developed covariant technology of excavating bosonic string trajectories, that is facilitated by the observation that the Virasoro constraints can be written as linear combinations of lowering operators of a bigger algebra, namely a symplectic algebra, which is Howe dual to the spacetime Lorentz algebra. For superstrings, it is the orthosymplectic algebra that appears instead, with its lowest weight states forming the simplest class of physical trajectories in the NS sector. To construct the simplest class in the R sector, the lowest weight states need to be supplemented with other states, which we determine. Deeper trajectories are then constructed by acting with suitable combinations of the raising operators of the orthosymplectic algebra, which we illustrate with several examples.

An excursion into the string spectrum

We propose a covariant technique to excavate physical bosonic string states by entire trajectories rather than individually. The approach is based on Howe duality: the string’s spacetime Lorentz algebra commutes with a certain inductive limit of sp(•), with the Virasoro constraints forming a subalgebra of the Howe dual algebra sp(•). There are then infinitely many simple trajectories of states, which are lowest-weight representations of sp(•) and hence of the Virasoro algebra. Deeper trajectories are recurrences of the simple ones and can be probed by suitable trajectory-shifting operators built out of the Howe dual algebra generators. We illustrate the formalism with a number of subleading trajectories and compute a sample of tree-level amplitudes.

Kinematic Analysis of the Kick Start Underwater Phase of Young Male Swimmers

Introduction: The introduction of a starting block with an adjustable and slanted footrest has caused the development of a new starting technique - the Kick Start. Therefore, research on swim start seems necessary, particularly concerning the Kick Start underwater phase. Aim: The study aim was to characterise the underwater phase of the Kick Start among young, male, competitive swimmers. Basic procedures. The study included 32 male, youth, competitive swimmers (mean age=16.61 years, height=1.80 m, body mass=72.47 kg, FINA Points=617). Participants executed three freestyle Kick Starts recorded using an underwater high-speed camera. Videos were kinematically analysed using the Skill Spector programme. Then, k-means clustering was applied. Results. Participants were classified into three clusters. Cluster FT (“flat trajectory”) comprised swimmers with a ”flat” course of underwater movement - low value of the angle of water attack (KA=0.92o), maximum depth of the head (hmax=0.85 m), distance (dmax=0.71 m), and time to maximum depth of the head (tmax=0.51 s). Group MT (“moderate trajectory”) had moderate values of the above-mentioned parameters (KA=10.27o, hmax=0.93 m, dmax=1.03 m, tmax=0.60 s), while Cluster DT (“deep trajectory”) achieved the highest values (KA=15.74o, hmax=1.05 m, dmax=1.38 m, tmax=0.73 s). The time to reach 15 m in Cluster FT was about 0.3 s slower than in Group MT and DT, although this dissimilarity was not significant. Conclusions. The course of underwater movement is mostly affected by the angle at which swimmers submerge. There is no “ideal” way to perform the underwater phase, however, it should not be executed too close to the water surface.

A small New Keynesian model to analyze business cycle dynamics in Poland and Romania

In this paper, we derive a small textbook New Keynesian DSGE model to evaluate Polish and Romanian business cycles during the 2003-2014 period. Given the similarities between the two economies, we use an identical calibration procedure for certain coefficients and marginal prior distributions for the others, rendering the resulting cross-country differences as primarily data-driven. The estimated structural coefficients for the two countries have comparable values, implying similar qualitative macroeconomic transmission mechanisms. However, the Romanian shocks display much more variability, and the impulse response functions have similar shapes but deeper trajectories. The model-simulated theoretical moments for the output growth, the inflation rate and the nominal interest rate (means, standard deviations and cross-correlations) are close to their actual data counterparts, demonstrating the models’ ability to match and replicate statistical properties of the observed variables. Shock decompositions of the output and the inflation rate revealed the driving forces of the business cycles; demand shocks explain much of the GDP growth dynamics (persistent positive contributions before the crisis and negative thereafter), whereas prices were also driven by supply and monetary policy shocks, the latter being more important for Poland.

Exploring ‘learning lives’: community, identity, literacy and meaning

AbstractThis article explores the term ‘learning lives’ by reporting on three research projects conducted by members of the Oslo‐based research group TransActions. By stressing the term ‘learning lives’ within a range of social ‘educational’ contexts, the article aims to look at learning within and across different learning sites exploring the positioning and repositioning of learner identity across these different ‘locations’. We emphasise how the individual learner relates to other people and objects, drawing on deeper trajectories or narratives of the self as it exists within and outside the immediate learning contexts. We pay attention to processes occurring between people which we find significant for the individual's identity, literacy and learning. By doing so we hope to make explicit the mobilisation of resources within and across specific contexts, in the ‘learning lives’ of Norwegian youngsters.

A framework for explaining the links between capacity and action in response to global climate change

Although great strides have been made towards a more nuanced understanding of the impacts and causes of global climate change, the ability to design and implement policy responses that engender effective action has remained insufficient. Recent framings of adaptive capacity and mitigative capacity are built upon in this article, and response capacity is introduced as a useful way to integrate adaptation and mitigation within the context of underlying development paths. In tracing the complex and non-linear relationships between response capacity—which represents a broad pool of development-related resources that can be mobilized in the face of any risk—and real policy and behaviour change in response to climate change, the strong influence of manifold socio-cultural factors is revealed. Only through an analysis of these deeper trajectories can the most important barriers to action begin to be addressed. Theories of risk perception are drawn upon to elucidate the complex nature of the relationship between capacity and action. A deeper understanding of these relationships will aid in the design and implementation of adaptation and mitigation policies that more effectively address the multitude of temporally and contextually specific intricacies of human behaviour in response to risks such as climate change. The literatures of institutional genesis and change, sociotechnical systems, social movements, and collective behaviour change theory (to name but a few) are argued to be crucial to an improved understanding of the underlying development paths which influence both capacity and action.