Random Chern-Simons matter in D=1D=1

We study a version of the 2-body Sachdev-Ye-Kitaev (SYK$_{2}$) model with complex fermions coupled to a 1-dimensional gauge field $A(t)$ with the aim of exploring a gauged AdS/SYK correspondence. The gauge field itself can be thought of as arising from a radial symmetry reduction of a $(2+1)$-dimensional Chern-Simons gauge field $A_{\mu}(t,\mathbf{x})$. Using the diagnostic tools of the out-of-time-order correlator (OTOC) and spectral form factor (SFF), which probe the sensitivity to initial conditions and the spectral statistics respectively, we give a detailed and pedagogical study of the integrable/chaotic properties of the model. We find that the coupling to the Chern-Simons gauge field has no effect on the OTOCs and, by extension, the early-time chaos properties of the model. We also find two notable effects of the gauge field on the spectral form factor; an enhancement of the early-time slope and the emergence of an explicit disorder scale needed for the manifestation of zero modes. These zero modes are responsible for the late-time exponential ramp in the quadratic SYK model.Comment: 25+3 pages and appendices; v2: Replaced figures which did not compile correctl

Splitting fields and general differential Galois theory

An algebraic technique is presented that does not use results of model theory and makes it possible to construct a general Galois theory of arbitrary nonlinear systems of partial differential equations. The algebraic technique is based on the search for prime differential ideals of special form in tensor products of differential rings. The main results demonstrating the work of the technique obtained are the theorem on the constructedness of the differential closure and the general theorem on the Galois correspondence for normal extensions..Comment: 33 pages, this version coincides with the published on

Building Mutual Understanding for Effective Development

In recent years a number of countries, referred to collectively as the rising powers, have achieved rapid economic growth and increased political influence. In many cases their experience challenges received wisdom on inclusive development. Research funded by traditional development donors has tended to focus on their own aid recipients. Policy analysts in the rising powers have faced several challenges in generating systematic learning from their countries’ rapidly changing development experiences. This has created a knowledge-sharing gap. The IDS Rising Powers in International Development programme invited highly experienced policymakers and analysts to review important development experiences from their countries, as Senior International Associates, creating new opportunities for mutual learning.UK Department for International Developmen

Antiretroviral therapy to prevent HIV acquisition in serodiscordant couples in a hyperendemic community in rural South Africa

Background. Antiretroviral therapy (ART) was highly efficacious in preventing human immunodeficiency virus (HIV) transmission in stable serodiscordant couples in the HPTN-052 study, a resource-intensive randomized controlled trial with near-perfect ART adherence and mutual HIV status disclosure among all participating couples. However, minimal evidence exists of the effectiveness of ART in preventing HIV acquisition in stable serodiscordant couples in "real-life" population-based settings in hyperendemic communities of sub-Saharan Africa, where health systems are typically resource-poor and overburdened, adherence to ART is often low, and partners commonly do not disclose their HIV status to each other. Methods. Data arose from a population-based open cohort in KwaZulu-Natal, South Africa. A total of 17 016 HIV-uninfected individuals present between January 2005 and December 2013 were included. Interval-censored time-updated proportional hazards regression was used to assess how the ART status affected HIV transmission risk in stable serodiscordant relationships. Results. We observed 1619 HIV seroconversions in 17 016 individuals, over 60 349 person-years follow-up time. During the follow-up period, 1846 individuals had an HIV-uninfected and 196 had an HIV-infected stable partner HIV incidence was 3.8/100 person-years (PY) among individuals with an HIV-infected partner (95% confidence interval [CI], 2.3-5.6), 1.4/100 PY (.4-3.5) among those with HIV-infected partners receiving ART, and 5.6/100 PY (3.5-8.4) among those with HIV-infected partners not receiving ART. Use of ART was associated with a 77% decrease in HIV acquisition risk among serodiscordant couples (adjusted hazard ratio, 0.23; 95% CI,. 07-.80). Conclusions. ART initiation was associated with a very large reduction in HIV acquisition in serodiscordant couples in rural KwaZulu-Natal. However, this "real-life" effect was substantially lower than the effect observed in the HPTN-052 trial. To eliminate HIV transmission in serodiscordant couples, additional prevention interventions are probably needed

Emergency Bipap Ventilator For Breathing Assistance

Journal ArticleThe paper proposes the concept of a simplified ventilation device that meets the requirements for the South African Health Products Regulatory Authority (SAHPRA) approval and may be manufactured in large numbers at moderate cost to meet the requirements of the current or future pneumonic type pandemics. The paper further describes the development of such a device and presents descriptions of the final prototype. The philosophy behind the design was to take an engineering view of the problem of safe ventilation, which also meets World Health Organisation (WHO) guideline ‘Technical specifications for invasive and non-invasive ventilators for COVID-19’ (2020), whilst using the human biological responses to control the aspiration boundaries, thereby avoiding the very complex processes which simulate the breathing mechanism. The methodology employed was a conceptual design phase followed by an engineering design phase, prototyping, testing, and further developments. The concept was based on guidelines from WHO, 2020: Technical specifications for invasive and non-invasive ventilators for COVID-19: Interim guidance: paragraphs 2.1.2 and 2.2.2.(2020) and measured against the UK standard of the Medicines and Healthcare Products Regulatory Agency (MHPRA) ‘Rapidly manufactured ventilator system’ (2020). Each component of the conceptual design was developed in this way and a final prototype was assembled for independent evaluation and eventual SAHPRA evaluation. The finished prototype meets WHO guidelines for a Bi-level Positive Airway Pressure (BiPAP) system and also meets the guideline requirements for portability. The prototype also meets the initial intent regarding simplicity, functionality and cost. The further developments to mass production will reduce the part count and assembly processes, with some components to be reconfigured as disposable items, not for sterilisation or re-use. The project has shown that specialised equipment may be viewed pragmatically according to the requirement — to treat all breathing difficulties with a full specification ventilator is not possible or necessary; to assist the majority of ostensibly minor cases with a Bi-PAP system is both practical and more affordable. The intent is not to compete with the high technology commercially sourced equipment, or even the rapidly prototyped re-purposed industrial efforts worldwide, but rather to initiate some progress in the Republic of South Africa to quickly produce an abundance of these machines, to cope with the possible deficit of medical ventilators expected in future. The solution lies in a simple but failsafe device that provides assisted breathing with the option of oxygen enrichment. It is intended to be locally manufactured with the minimum of skills and is easily maintained and sterilised

Electromagnetic transition from the 4+^+ to 2+^+ resonance in 8^8Be measured via the radiative capture in 4^4He+4^4He

An earlier measurement on the 4$^+$ to 2$^+$ radiative transition in $^8$Be provided the first electromagnetic signature of its dumbbell-like shape. However, the large uncertainty in the measured cross section does not allow a stringent test of nuclear structure models. The present paper reports a more elaborate and precise measurement for this transition, via the radiative capture in the $^4$He+$^4$He reaction, improving the accuracy by about a factor of three. The {\it ab initio} calculations of the radiative transition strength with improved three-nucleon forces are also presented. The experimental results are compared with the predictions of the alpha cluster model and {\it ab initio} calculations.Comment: 5 pages and 7 figures, Submitted to Physical Review Letter

The calibrated population resistance tool: standardized genotypic estimation of transmitted HIV-1 drug resistance

Summary: The calibrated population resistance (CPR) tool is a web-accessible program for performing standardized genotypic estimation of transmitted HIV-1 drug resistance. The program is linked to the Stanford HIV drug resistance database and can additionally perform viral genotyping and algorithmic estimation of resistance to specific antiretroviral drugs

HIV-1 viral load is elevated in individuals with reverse transcriptase mutation M184V/I during virological failure of first line antiretroviral therapy and is associated with compensatory mutation L74I

Background: M184V/I cause high-level lamivudine (3TC) and emtricitabine (FTC) resistance, and increased tenofovir (TDF) susceptibility. Nonetheless, 3TC and FTC (collectively referred to as XTC) appear to retain modest activity against HIV-1 with these mutations possibly as a result of reduced replication capacity. Here we determined how M184V/I impacts virus load (VL) in patients failing therapy on a TDF/XTC plus nonnucleoside RT inhibitor (NNRTI)-containing regimen. / Methods: We compared VL in absence and presence M184V/I across studies using random effects meta-analysis. The effect of mutations on virus RT activity and infectiousness was analysed in vitro. / Results: M184I/V was present in 817 (56.5%) of 1445 individuals with VF. VL was similar in individuals with or without M184I/V (difference in log10VL 0.18, 95% CI 0.05-0.31). CD4 count was lower both at initiation of ART and at VF in participants who went on to develop M184V/I. L74I was present in 10.2% of persons with M184V/I but absent in persons without M184V/I (p<0.0001). In vitro, L74I compensated for defective replication of M184V mutated virus. / Conclusion: Virus loads were similar in persons with and without M184V/I during VF on a TDF/XTC/NNRTI-containing regimen. We therefore do not find evidence for a benefit of XTC in the context of first line failure on this combination

Medical cannabis: What practitioners need to know

The South African (SA) Constitutional Court recently decriminalised the private cultivation, possession and use of cannabis by adults. Cannabis contains varying amounts of the cannabinoids delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), depending on various cultivation factors. No commercial plant-derived cannabis products are currently registered by the SA Health Products Regulatory Authority (SAHPRA) for medical use. Such products are therefore unregulated, but are freely available in SA, and may be of inadequate quality and unverified composition, and not guaranteed to be safe or effective. SAHPRA has to date approved only one synthetic medical cannabis product, dronabinol. Evidence supporting benefit from medical cannabis exists for two drug-resistant childhood forms of epilepsy, Dravet syndrome and Lennox-Gastaut syndrome. Adjuvant therapy with medical cannabis can reduce seizure frequency for Lennox-Gastaut syndrome and Dravet syndrome by 18.8% and 22.8%, respectively, and may be beneficial for other rare forms of epilepsy. There is moderate evidence for chemotherapy-induced nausea and vomiting with the synthetic cannabinoids. Multiple sclerosis-associated spasticity showed a small clinical improvement in self-reported spasticity when a purified form of THC/CBD was added to existing therapy. Currently, low-level or no convincing evidence exists for the use of medical cannabis for chronic pain, sleep and weight disorders, and neuropsychiatric disorders. Cannabis is associated with a greater risk of adverse effects than active and placebo controls, and may be involved in clinically significant drug-drug interactions. The evolving regulatory and legal landscape on the use of medical cannabis will guide prescription and recreational use in the coming years