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Information-theoretic criteria for optimizing designs of individually randomized stepped-wedge clinical trials
No full textClinical trials are essential for advancing medical knowledge and improving health care, with Randomized Clinical Trials (RCTs) considered the gold standard for minimizing bias and generating reliable evidence on treatment efficacy and safety. Stepped-wedge individual RCTs, which randomize participants into sequences transitioning from control to intervention at staggered time points, are increasingly adopted. To improve their design, we propose an information-theoretic framework based on D– and A–optimality criteria for participant allocation to sequences. Our approach leverages semidefinite programming for automated computation and is applicable across a range of settings, varying in: (i) number of sequences, (ii) attrition rates, (iii) optimality criteria, (iv) error correlation structures, and (v) multi-objective designs using the ϵ-constraint method
Introduction
No full textThis chapter provides an introduction to the book. The twelve essays in the book fall into three groups. Essays in the first group address problems in the philosophy of mathematics; essays in the second group investigate foundational questions concerning Lakatos's philosophy of science; and essays in the third group apply Lakatos's concept of Methodology of Scientific Research Programmes (MSRP) to medicine. The book ends with an epilogue
Sovereignty, nationalism, and the quest for homogeneity in interwar Europe edited by Emmanuel Dalle Mulle, Davide Rodogno, and Monica Bieling London: Bloomsbury Academic, 2023, pp. xvii + 304 ISBN: 978‐1‐3502‐6338‐3
No full textThe puzzling decline of polarization of opportunity in the US
No full textA society where opportunities are highly polarized is one where individuals are clustered around some factor outside of their choosing – like race or place of birth – with each cluster having wildly different life prospects. Paolo Brunori, Vanesa Jordá and Pedro Salas-Rojo introduce the concept and chart the surprising decline of polarization of opportunity in the US in recent decades
Why Trump may have an incentive to leverage crypto into Silicon Valley's political downfall
No full textCorporate power in America often means that politicians, including presidents, have difficulty in confronting business elites. Nikhil Kalyanpur writes that Donald Trump and Elon Musk’s recent falling out is an unusual example of a president taking on one of their former corporate backers. He suggests that Trump could use his and his family’s stake in cryptocurrency to turn his conflict with Silicon Valley elites into profit, a fight that he may be guaranteed to win
Universities are engines of growth and must be backed by policy
No full textThe UK’s Industrial Strategy identifies growth-driving sectors that will require a highly-skilled workforce. Higher education will be a key to unlocking this ambition. But as universities aim to recruit the best talent from around the world, Aadya Bahl and Sandra McNally write that the Government’s recent immigration policies risk destabilising the sector at the very moment it is being asked to do more
A first order method for linear programming parameterized by circuit imbalance
No full textVarious first order approaches have been proposed in the literature to solve Linear Programming (LP) problems, recently leading to practically efficient solvers for large-scale LPs. From a theoretical perspective, linear convergence rates have been established for first order LP algorithms, despite the fact that the underlying formulations are not strongly convex. However, the convergence rate typically depends on the Hoffman constant of a large matrix that contains the constraint matrix, as well as the right hand side, cost, and capacity vectors. We introduce a first order approach for LP optimization with a convergence rate depending polynomially on the circuit imbalance measure, which is a geometric parameter of the constraint matrix, and depending logarithmically on the right hand side, capacity, and cost vectors. This provides much stronger convergence guarantees. For example, if the constraint matrix is totally unimodular, we obtain polynomial-time algorithms, whereas the convergence guarantees for approaches based on primal-dual formulations may have arbitrarily slow convergence rates for this class. Our approach is based on a fast gradient method due to Necoara, Nesterov, and Glineur (Math. Prog. 2019); this algorithm is called repeatedly in a framework that gradually fixes variables to the boundary. This technique is based on a new approximate version of Tardos’s method, that was used to obtain a strongly polynomial algorithm for combinatorial LPs (Oper. Res. 1986)
Productivity and reconfiguration practices in entrepreneurship: the COVID-19 lockdown as a test of entrepreneurs’ response to disruption
No full textEvidence from African nations where high unemployment rates make entrepreneurship more appealing shows the quality of entrepreneurship education encourages business creation. Prior literature asserts high-quality entrepreneurship education must leverage actionable practices. We argue the entrepreneurial expertise of developed economies shapes the support they provide to emerging economies; thus, examining that expertise can yield global benefits. We begin with the theoretical premise that all businesses require practices for both productivity (i.e., ordinary capabilities) and reconfiguration (i.e., dynamic capabilities). However, most attention—both in developed economies (e.g., U.S. Census Bureau surveys) and in development interventions—is focused solely on productivity practices. To assess whether this focus is optimal, we treat the first COVID-19 lockdowns as a natural skills test for entrepreneurs and interview 21 small-business owners in the competitive, cash-constrained restaurant sectors in London and San Francisco. We learn interviewees master productivity practices but struggle with reconfiguration ones. Moreover, entrepreneurs may be aware of a reconfiguration practice but have difficulty implementing it. Furthermore, through a disruption, productivity practices can crowd out reconfiguration practices even in small businesses. Overall, we argue some businesses had highquality productivity and reconfiguration practices because they had a rudimentary innovation system. We recommend jointly leveraging the productivity literature and the emerging literature on theory-based entrepreneurship, especially as now applied to the African context. Moreover, we recommend adding topics relevant to responding to disruption, such as rudimentary innovation systems, to the curriculum development
Productivity and reconfiguration practices in entrepreneurship: the COVID-19 lockdown as a test of entrepreneurs’ response to disruption
No full textEvidence from African nations where high unemployment rates make entrepreneurship more appealing shows the quality of entrepreneurship education encourages business creation. Prior literature asserts high-quality entrepreneurship education must leverage actionable practices. We argue the entrepreneurial expertise of developed economies shapes the support they provide to emerging economies; thus, examining that expertise can yield global benefits. We begin with the theoretical premise that all businesses require practices for both productivity (i.e., ordinary capabilities) and reconfiguration (i.e., dynamic capabilities). However, most attention—both in developed economies (e.g., U.S. Census Bureau surveys) and in development interventions—is focused solely on productivity practices. To assess whether this focus is optimal, we treat the first COVID-19 lockdowns as a natural skills test for entrepreneurs and interview 21 small-business owners in the competitive, cash-constrained restaurant sectors in London and San Francisco. We learn interviewees master productivity practices but struggle with reconfiguration ones. Moreover, entrepreneurs may be aware of a reconfiguration practice but have difficulty implementing it. Furthermore, through a disruption, productivity practices can crowd out reconfiguration practices even in small businesses. Overall, we argue some businesses had highquality productivity and reconfiguration practices because they had a rudimentary innovation system. We recommend jointly leveraging the productivity literature and the emerging literature on theory-based entrepreneurship, especially as now applied to the African context. Moreover, we recommend adding topics relevant to responding to disruption, such as rudimentary innovation systems, to the curriculum development
Spatio-temporal trends and socio-environmental determinants of suicides in England (2002–2022) an ecological population-based study
No full textBackground: Over the last two decades of suicide prevention strategy implementation, suicide rates in England have shown a fluctuating pattern, declining from the early 2000s (10.3 deaths per 100,000 in 2002) until around 2010 (9.0 deaths per 100,000 in 2007), then gradually increasing (10.7 deaths per 100,000 in 2022). It remains unclear whether the pattern varies by local area, the influence of the socio-environmental factors or a combination of both. Our aim was to evaluate spatio-temporal trends of suicides in England from 2002 to 2022 whilst examining the role of socio-environmental characteristics. Methods: In this ecological study, we analysed Office for National Statistics data on deaths by suicide, exploring spatial and temporal patterns in England (2002–2022). Using a Hurdle Poisson model fit within a Bayesian hierarchical framework, we assessed the effects of local area level deprivation, ethnic density, population density, light pollution, railway and road network densities and greenspace composition on suicide risk. Findings: From 2002 to 2022, suicide risk across England showed no substantial change overall (−4.26%; 95% Credible Interval (CrI): −8.95%, 0.72%). The difference between the regions with the lowest (London) and highest (North East) risk was 39.2% (95% CrI: 34.1%, 44.3%). We found that for one standard deviation change in each covariate, suicide risk increased with deprivation (20.06%; 95% CrI: 18.48%, 21.65%), railway network density (1.37%; 95% CrI: 0.32%, 2.46%), and road network density (5.16%; 95% CrI: 3.12%, 7.46%) while risk decreased with ethnic density (−7.47%; 95% CrI: −8.91%, −6.00%), population density (−5.42%; 95% CrI: −7.34%, −3.25%), light pollution (−4.20%; 95% CrI: −5.71%, −2.72%), and greenspace composition (−6.43%; 95% CrI: −7.94%, −4.99%). Interpretation: We did not find evidence to support a decline in suicide rates in England over the last 20 years and our findings highlight the community profiles, characterised by greater deprivation, isolation, and access to road/rail networks, where suicide risk was highest. This should help focus future research to understand these as drivers of suicide risk, leading to the development of effective area-level interventions and targeted investment in those approaches where most needed. Funding: Wellcome Trust, UKHSA, MRC, NIHR through its HPRU, HDRUK, NIHR University College Hospital London (UCLH) Biomedical Research Centre (BRC)