Non-stationary Stochastic Optimization

We consider a non-stationary variant of a sequential stochastic optimization problem, in which the underlying cost functions may change along the horizon. We propose a measure, termed variation budget, that controls the extent of said change, and study how restrictions on this budget impact achievable performance. We identify sharp conditions under which it is possible to achieve long-run-average optimality and more refined performance measures such as rate optimality that fully characterize the complexity of such problems. In doing so, we also establish a strong connection between two rather disparate strands of literature: adversarial online convex optimization; and the more traditional stochastic approximation paradigm (couched in a non-stationary setting). This connection is the key to deriving well performing policies in the latter, by leveraging structure of optimal policies in the former. Finally, tight bounds on the minimax regret allow us to quantify the "price of non-stationarity," which mathematically captures the added complexity embedded in a temporally changing environment versus a stationary one

Three-Prong Distribution of Massive Narrow QCD Jets

We study the planar-flow distributions of narrow, highly boosted, massive QCD jets. Using the factorization properties of QCD in the collinear limit, we compute the planar-flow jet function from the one-to-three splitting function at tree-level. We derive the leading-log behavior of the jet function analytically. We also compare our semi-analytic jet function with parton-shower predictions using various generators.Comment: 59 pages, 9 figure

Poverty, Tobacco, and Health: An Indian Scenario

Poverty and health have a two-way relationship. Poverty increases the vulnerability of people to disease, and sickness affects their income leading to poverty. Tobacco has been identified as a major avoidable cause of illness and premature death. In India, more than half of men and one-tenth of women use one or more forms of tobacco. Tobacco-use shows a clear and continual increase with decreasing wealth quintiles. Poor smokers, who are at a greater risk of illness, are also at a greater risk of not being treated or of falling into greater poverty if they seek treatment. Poor people spend money on tobacco that could be spent on food, shelter, education, and healthcare. These decisions can entrench families in an ongoing cycle of poverty and ill-health. The direct and indirect costs of tobacco-use are immense for national economy. This has positioned control of tobacco relevant in India's per suite to achieve the goals of poverty eradication and health for all

Dissolution kinetics and mechanism of pandermite in acetic acid solutions

In this study, the dissolution kinetics and mechanism of pandermite mineral was investigated using a batch reactor employing the parameters of particle size, acid concentration, solid/liquid ratio, stirring speed and reaction temperature. From experimental data, it was determined that the conversion rate of pandermite to boric acid was increased with decreasing particle size, solid/ liquid ratio and increasing reaction temperature. Conversion rate increased up to 3 M, acid concentration then decreased with increasing acid concentration.It was observed that there was no important effect of stirring speed on the dissolution rate. Furthermore, it was observed that the dissolution mechanism was dependent on acid concentration due to restriction of dissolution in acetic acid solutions. The dissolution rate of pandermite mineral in acetic acid solution was examined according to homogeneous and heterogeneous chemical reaction model. It was determined from graphical and statistical methods that the reaction kinetics fitted to model in the form of first order pseudo homogeneous model [- ln (1 - X)] = kt and activation energy for the dissolution process was found to be 28.496 kj/mol. A mathematicalmodel, which indicated the dissolution process was established

Striatal intrinsic reinforcement signals during recognition memory: relationship to response bias and dysregulation in schizophrenia

Ventral striatum (VS) is a critical brain region for reinforcement learning and motivation, and VS hypofunction is implicated in psychiatric disorders including schizophrenia. Providing rewards or performance feedback has been shown to activate VS. Intrinsically motivated subjects performing challenging cognitive tasks are likely to engage reinforcement circuitry even in the absence of external feedback or incentives. However, such intrinsic reinforcement responses have received little attention, have not been examined in relation to behavioral performance, and have not been evaluated for impairment in neuropsychiatric disorders such as schizophrenia. Here we used fMRI to examine a challenging “old” vs. “new” visual recognition task in healthy subjects and patients with schizophrenia. Targets were unique fractal stimuli previously presented as salient distractors in a visual oddball task, producing incidental memory encoding. Based on the prediction error theory of reinforcement learning, we hypothesized that correct target recognition would activate VS in controls, and that this activation would be greater in subjects with lower expectation of responding correctly as indexed by a more conservative response bias. We also predicted these effects would be reduced in patients with schizophrenia. Consistent with these predictions, controls activated VS and other reinforcement processing regions during correct recognition, with greater VS activation in those with a more conservative response bias. Patients did not show either effect, with significant group differences suggesting hyporesponsivity in patients to internally generated feedback. These findings highlight the importance of accounting for intrinsic motivation and reward when studying cognitive tasks, and add to growing evidence of reward circuit dysfunction in schizophrenia that may impact cognition and function

Harnessing the benefits of sanctuary scholarship: opportunities for community enhancement, widening participation and internationalisation at home

The paper focuses on the importance of Internationalisation at Home, access and support mechanisms which are provided and co-created by students and university departments to encourage sanctuary scholarship. The paper gives particular attention to activities that encourage meaningful interaction with local communities and widen international participation of marginalised groups, such as students from the global south and asylum seeker communities. The paper presents two case studies. The first case study focuses on a student-led project developed by the students and staff of Canterbury Christ Church University. The second case study projects students’ voices from the global south and refugee communities at The University of Kent and University College London (UCL). The experiences of these students highlight the importance of welcoming and supporting students from marginalised backgrounds. They also demonstrate the need for both curriculum-based and co-curricular activity and student services which provided tailored support and encouragement