Superlinear Scaling for Innovation in Cities

Superlinear scaling in cities, which appears in sociological quantities such as economic productivity and creative output relative to urban population size, has been observed but not been given a satisfactory theoretical explanation. Here we provide a network model for the superlinear relationship between population size and innovation found in cities, with a reasonable range for the exponent.Comment: 5 pages, 5 figures, 1 table, submitted to Phys. Rev. E; references corrected; figures corrected, references and brief discussion adde

Computational Complexity of Time-Dependent Density Functional Theory

Time-dependent density functional theory (TDDFT) is rapidly emerging as a premier method for solving dynamical many-body problems in physics and chemistry. The mathematical foundations of TDDFT are established through the formal existence of a fictitious non-interacting system (known as the Kohn–Sham system), which can reproduce the one-electron reduced probability density of the actual system. We build upon these works and show that on the interior of the domain of existence, the Kohn–Sham system can be efficiently obtained given the time-dependent density. We introduce a V-representability parameter which diverges at the boundary of the existence domain and serves to quantify the numerical difficulty of constructing the Kohn–Sham potential. For bounded values of V-representability, we present a polynomial time quantum algorithm to generate the time-dependent Kohn–Sham potential with controllable error bounds.Chemistry and Chemical Biolog

Spin Star as Switch for Quantum Networks

Quantum state transfer is an important task in quantum information processing. It is known that one can engineer the couplings of a one-dimensional spin chain to achieve the goal of perfect state transfer. To leverage the value of these spin chains, a spin star is potentially useful for connecting different parts of a quantum network. In this work, we extend the spin-chain engineering problem to the problems with a topology of a star network. We show that a permanently coupled spin star can function as a network switch for transferring quantum states selectively from one node to another by varying the local potentials only. Together with one-dimensional chains, this result allows applications of quantum state transfer be applied to more general quantum networks.Comment: 10 pages, 2 figur

An improved model of the vacuum probe

Vacuum probe microbiological device for sampling large areas lightly loaded with microorganism

The impact of COVID-19 restrictions on needle and syringe programme provision and coverage in England

Background The restrictions introduced in response to COVID-19 present many challenges, particularly for vulnerable and marginalised populations. These include maintaining access to Needle and Syringe Programmes (NSPs) to reduce the harms associated with injecting drugs. NSPs effectiveness is coverage dependent, but lockdowns and social distancing limit NSP access and availability. The impact on NSP provision in England is explored using enhanced monitoring data. Method Data collected through an established comprehensive monitoring system from five four-week periods, centred on the implementation of restrictions in the UK in mid-March 2020, are examined. Weekly averages are compared to allow for public holidays and weekly variation in activity. Results The restrictions resulted in the number of NSP clients decreasing by 36%, visits by 36%, and needles distributed by 29%. NSP coverage for those injecting psychoactive drugs halved, declining from 14 needles per-week during the 4-weeks to 15th March 2020 to 7 needles per-week by mid-April, and coverage has remained at this level since then. Conclusions Though it is currently unclear if there has been a decline in injecting, the decline in NSP coverage is so marked that it almost certainly reflects decreased utilisation among those in need, indicating increased equipment reuse and risk

Longitudinal Flow of Protons from 2-8 AGeV Central Au+Au Collisions

Rapidity distributions of protons from central $^{197}$Au + $^{197}$Au collisions measured by the E895 Collaboration in the energy range from 2 to 8 AGeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, $_{L}$, as a function of the logarithm of beam energy.Comment: 5 Pages, including 3 figures, 1 tabl

Integrated Monitoring System Annual Report - Cheshire and Merseyside, 2016-17

The annual report for the Integrated Monitoring System (IMS) details activity across Merseyside and Cheshire over the period of the 2016-17 financial year. The report provides information on presentations to needle and syringe programmes (NSPs) and other low threshold interventions delivered to individuals using drugs and/or alcohol, focussing on areas such as wellbeing, demographics and substances used. The data is presented in three distinct cohort groups; 1) individuals injecting psychoactive drugs, 2) individuals injecting steroids/IPEDs, 3) individuals accessing support related to alcohol or non-injecting drug use. Data from IMS is also cross-matched with the National Drug Treatment Monitoring System (NDTMS) and the Criminal Justice Dataset to provide a complete picture of activity within each of the nine Local Authority areas in Cheshire and Merseyside. The report also provides an overview of published and future research in the field at both a local and national level

Near-threshold production of the multi-strange Ξ−\Xi^- hyperon

The yield for the multi-strange $\Xi^{-}$ hyperon has been measured in 6 AGeV Au+Au collisions via reconstruction of its decay products $\pi^{-}$ and $\Lambda$, the latter also being reconstructed from its daughter tracks of $\pi^{-}$ and p. The measurement is rather close to the threshold for $\Xi^{-}$ production and therefore provides an important test of model predictions. The measured yield for $\Xi^{-}$ and $\Lambda$ are compared for several centralities. In central collisions the $\Xi^{-}$ yield is found to be in excellent agreement with statistical and transport model predictions, suggesting that multi-strange hadron production approaches chemical equilibrium in high baryon density nuclear matter.Comment: Submitted to PR