Truthful Multi-unit Procurements with Budgets

We study procurement games where each seller supplies multiple units of his item, with a cost per unit known only to him. The buyer can purchase any number of units from each seller, values different combinations of the items differently, and has a budget for his total payment. For a special class of procurement games, the {\em bounded knapsack} problem, we show that no universally truthful budget-feasible mechanism can approximate the optimal value of the buyer within $\ln n$, where $n$ is the total number of units of all items available. We then construct a polynomial-time mechanism that gives a $4(1+\ln n)$-approximation for procurement games with {\em concave additive valuations}, which include bounded knapsack as a special case. Our mechanism is thus optimal up to a constant factor. Moreover, for the bounded knapsack problem, given the well-known FPTAS, our results imply there is a provable gap between the optimization domain and the mechanism design domain. Finally, for procurement games with {\em sub-additive valuations}, we construct a universally truthful budget-feasible mechanism that gives an $O(\frac{\log^2 n}{\log \log n})$-approximation in polynomial time with a demand oracle.Comment: To appear at WINE 201

Evaluating palliative care training in the oncology registrar programme in South Africa

Background. Following a World Health Assembly call in 2014 to strengthen palliative care, the South African (SA) Department of Health approved this strategy as part of the SA National Policy Framework and Strategy on Palliative Care. In 2016, the University of Cape Town, together with the College of Radiation Oncology of SA, identified the need to integrate palliative care (PC) into the oncology curriculum. In collaboration with the Cancer Association of SA, a research project was developed to introduce a 12-module curriculum at five teaching hospitals. The aim of this research was to evaluate the impact of a 1-year PC course within the training programme for specialist oncologists in SA. Objective. To determine the reaction of oncology registrars and their supervisors to the course to determine changes in knowledge and skills, and to determine the application in oncology practice. Methods. This study was a mixed-method prospective evaluation of an educational intervention. The educational programme used a blended learning method to train and support registrars (n=32) and facilitators (n=5) across five universities from August 2017 to September 2018. Evaluation feedback was electronically collected to determine the registrars’ reactions to the course materials. Pre and post multiple-choice questions (MCQs) were used to review their knowledge. Focus group discussions (FGDs) were used to explore reactions, change in knowledge and skills and how registrars integrated PC into their daily work. Results. There was an overwhelmingly positive reaction to the PC course by the oncology registrars and their supervisors. The training was found to be feasible, and the topics addressed appropriate. Concerns previously raised by the College of Radiation Oncology of SA regarding the feasibility and appropriateness of the course and material were found to be unsubstantiated. The poor MCQ results can be ascribed to poor sequencing of the execution of the question. However, the MCQs in modules 7 and 8 (symptom management) demonstrated the most significant change in knowledge and skills (symptom management). The FGDs demonstrated a perceived change in knowledge and skills, especially for communication skills and pain and symptom management. The FGDs also indicated that the registrars’ approach to PC changed in that they were able to integrate the principles of PC into practice, and now saw PC as an essential component of oncology. Lastly, registrars and their supervisors felt that the course addressed topics that formed part of their daily clinical work. Conclusion. This research supports the view that PC training is an essential component of oncology training in the SA setting. PC forms part of the daily practice of oncologists, and a structured curriculum prepares clinicians to be able to integrate evidence-based PC into the practice of oncology if they receive appropriate training. Supervisors of the oncology training programme and registrars are confident that the training of 12 modules across 1 year is feasible and appropriate

Flight Lieutenant Peach’s observations on Burning Feet Syndrome in Far Eastern Prisoners of War 1942-45

This historical review analyses ‘Burning Feet Syndr ome’, a condition suffered by Far Eastern Prisoners of War in the Second World War. Case reco rds from RAF doctor Nowell Peach, written at the time, are retrospectively assessed a gainst modern diagnostic criteria to determine if the syndrome can be retrospectively cl assed as neuropathic pain

Investigation of shock waves in explosive blasts using fibre optic pressure sensors

The published version of this article may be accessed at the link below. Copyright @ IOP Publishing, 2006.We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1 mm(2) in overall cross-section with rise times in the mu s regime and pressure ranges typically 900 kPa (9 bar). Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Results from blast tests are presented in which up to six sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.Support from the UK Engineering&Physical Sciences Research Council and Dstl Fort Halstead through the MoD Joint Grants Scheme are acknowledged. WN MacPherson is supported by an EPSRC Advanced Research Fellowship

Mechanisms of network changes in cognitive impairment in multiple sclerosis

Background and objectives: Cognitive impairment in multiple sclerosis (MS) is associated with functional connectivity abnormalities. While there have been calls to use functional connectivity measures as biomarkers, there remains to be a full understanding of why they are affected in MS. In this cross-sectional study, we tested the hypothesis that functional network regions may be susceptible to disease-related "wear and tear" and that this can be observable on co-occurring abnormalities on other magnetic resonance metrics. We tested whether functional connectivity abnormalities in cognitively impaired patients with MS co-occur with (1) overlapping, (2) local, or (3) distal changes in anatomic connectivity and cerebral blood flow abnormalities. Methods: Multimodal 3T MRI and assessment with the Brief Repeatable Battery of Neuropsychological tests were performed in 102 patients with relapsing-remitting MS and 27 healthy controls. Patients with MS were classified as cognitively impaired if they scored ≥1.5 SDs below the control mean on ≥2 tests (n = 55) or as cognitively preserved (n = 47). Functional connectivity was assessed with Independent Component Analysis and dual regression of resting-state fMRI images. Cerebral blood flow maps were estimated, and anatomic connectivity was assessed with anatomic connectivity mapping and fractional anisotropy of diffusion-weighted MRI. Changes in cerebral blood flow and anatomic connectivity were assessed within resting-state networks that showed functional connectivity abnormalities in cognitively impaired patients with MS. Results: Functional connectivity was significantly decreased in the anterior and posterior default mode networks and significantly increased in the right and left frontoparietal networks in cognitively impaired relative to cognitively preserved patients with MS (threshold-free cluster enhancement corrected at p ≤ 0.05, 2 sided). Networks showing functional abnormalities showed altered cerebral blood flow and anatomic connectivity locally and distally but not in overlapping locations. Discussion: We provide the first evidence that functional connectivity abnormalities are accompanied by local cerebral blood flow and structural connectivity abnormalities but also demonstrate that these effects do not occur in exactly the same location. Our findings suggest a possibly shared pathologic mechanism for altered functional connectivity in brain networks in MS

Exact Results on the Space of Vacua of Four Dimensional SUSY Gauge Theories

We consider four dimensional quantum field theories which have a continuous manifold of inequivalent exact ground states -- a moduli space of vacua. Classically, the singular points on the moduli space are associated with extra massless particles. Quantum mechanically these singularities can be smoothed out. Alternatively, new massless states appear there. These may be the elementary massless particles or new massless bound states.Comment: 19 pages, RU-94-1

Optimizing trade-offs among stakeholders in real-time bidding by incorporating multimedia metrics

Displaying banner advertisements (in short, ads) on webpages has usually been discussed as an Internet economics topic where a publisher uses auction models to sell an online user's page view to advertisers and the one with the highest bid can have her ad displayed to the user. This is also called \emph{real-time bidding} (RTB) and the ad displaying process ensures that the publisher's benefit is maximized or there is an equilibrium in ad auctions. However, the benefits of the other two stakeholders -- the advertiser and the user -- have been rarely discussed. In this paper, we propose a two-stage computational framework that selects a banner ad based on the optimized trade-offs among all stakeholders. The first stage is still auction based and the second stage re-ranks ads by considering the benefits of all stakeholders. Our metric variables are: the publisher's revenue, the advertiser's utility, the ad memorability, the ad click-through rate (CTR), the contextual relevance, and the visual saliency. To the best of our knowledge, this is the first work that optimizes trade-offs among all stakeholders in RTB by incorporating multimedia metrics. An algorithm is also proposed to determine the optimal weights of the metric variables. We use both ad auction datasets and multimedia datasets to validate the proposed framework. Our experimental results show that the publisher can significantly improve the other stakeholders' benefits by slightly reducing her revenue in the short-term. In the long run, advertisers and users will be more engaged, the increased demand of advertising and the increased supply of page views can then boost the publisher's revenue

Flight Lieutenant Peach's observations on Burning Feet Syndrome in Far Eastern Prisoners of War 1942-45.

Introduction: ‘Burning Feet Syndrome’ affected up to one third of Far Eastern Prisoners of War in World War 2. Recently discovered medical records, produced by RAF Medical Officer Nowell Peach whilst in captivity, are the first to detail neurological examinations of patients with this condition. Methods: The 54 sets of case notes produced at the time were analysed using modern diagnostic criteria to determine if the syndrome can be retrospectively classed as neuropathic pain. Results: With a history of severe malnutrition raising the possibility of a peripheral polyneuropathy, and a neuroanatomically plausible pain distribution, this analysis showed that Burning Feet Syndrome can now be described as a ‘possible’ neuropathic pain syndrome. Conclusion: After 70 years, the data painstakingly gathered under the worst of circumstances have proved to be of interest and value in modern diagnostics of neuropathic pain

Supersymmetric QCD: Exact Results and Strong Coupling

We revisit two longstanding puzzles in supersymmetric gauge theories. The first concerns the question of the holomorphy of the coupling, and related to this the possible definition of an exact (NSVZ) beta function. The second concerns instantons in pure gluodynamics, which appear to give sensible, exact results for certain correlation functions, which nonetheless differ from those obtained using systematic weak coupling expansions. For the first question, we extend an earlier proposal of Arkani-Hamed and Murayama, showing that if their regulated action is written suitably, the holomorphy of the couplings is manifest, and it is easy to determine the renormalization scheme for which the NSVZ formula holds. This scheme, however, is seen to be one of an infinite class of schemes, each leading to an exact beta function; the NSVZ scheme, while simple, is not selected by any compelling physical consideration. For the second question, we explain why the instanton computation in the pure supersymmetric gauge theory is not reliable, even at short distances. The semiclassical expansion about the instanton is purely formal; if infrared divergences appear, they spoil arguments based on holomorphy. We demonstrate that infrared divergences do not occur in the perturbation expansion about the instanton, but explain that there is no reason to think this captures all contributions from the sector with unit topological charge. That one expects additional contributions is illustrated by dilute gas corrections. These are infrared divergent, and so difficult to define, but if non-zero give order one, holomorphic, corrections to the leading result. Exploiting an earlier analysis of Davies et al, we demonstrate that in the theory compactified on a circle of radius beta, due to infrared effects, finite contributions indeed arise which are not visible in the formal limit that beta goes to infinity.Comment: 28 pages, two references added, one typo correcte