Convergence and evaluation-complexity analysis of a regularized tensor-Newton method for solving nonlinear least-squares problems

Given a twice-continuously differentiable vector-valued function r(x), a local minimizer of ∥r(x)∥2 is sought. We propose and analyse tensor-Newton methods, in which r(x) is replaced locally by its second-order Taylor approximation. Convergence is controlled by regularization of various orders. We establish global convergence to a first-order critical point of ∥r(x)∥2, and provide function evaluation bounds that agree with the best-known bounds for methods using second derivatives. Numerical experiments comparing tensor-Newton methods with regularized Gauss-Newton and Newton methods demonstrate the practical performance of the newly proposed method

The role of microbiology and pharmacy departments in the stewardship of antibiotic prescribing in European hospitals

This observational, cross-sectional study describes the role played by clinical microbiology and pharmacy departments in the stewardship of antibiotic prescribing in European hospitals. A total of 170 acute care hospitals from 32 European countries returned a questionnaire on antibiotic policies and practices implemented in 2001. Data on antibiotic use, expressed as De.ned Daily Doses per 100 occupied bed-days (DDD/100 BD) were provided by 139 hospitals from 30 countries. A total of 124 hospitals provided both datasets. 121 (71%) of Clinical Microbiology departments and 66 (41%) of Pharmacy departments provided out of hours clinical advice. 70 (41%) of microbiology/infectious disease specialists and 28 (16%) of pharmacists visited wards on a daily basis. The majority of laboratories provided monitoring of blood cultures more than once per day and summary data of antibiotic susceptibility testing (AST) for empiric prescribing (86% and 73% respectively). Most of the key laboratory and pharmacy-led initiatives examined did not vary signi.cantly by geographical location. Hospitals from the North and West of Europe were more likely to examine blood cultures more than once daily compared with other regions (p < 0.01). Hospitals in the North were least likely routinely to report susceptibility results for restricted antibiotics compared to those in the South-East and Central/Eastern Europe (p < 0.01). Hospital wards in the North were more likely to hold antibiotic stocks (100%) compared with hospitals in the South-East which were least likely (39%) (p < 0.001). Conversely, hospital pharmacies in the North were least likely to dispense antibiotics on an individual patient basis (16%) compared with hospital pharmacies from Southern Europe (60%) (p = 0.01). Hospitals that routinely reported susceptibility results for restricted antibiotics had signi.cantly lower median total antibiotic use in 2001 (p < 0.01). Hospitals that provided prescribing advice outside normal working hours had signi.cantly higher antibiotic use compared with institutions that did not provide this service (p = 0.01). A wide range of antibiotic stewardship measures was practised in the participating hospitals in 2001, although there remains great scope for expansion of those overseen by pharmacy departments. Most hospitals had active antibiotic stewardship programmes led by specialists in infection, although there is no evidence that these were associated with reduced antibiotic consumption. There was also no evidence that pharmacy services reduced the amount of antibiotics prescribed.The ARPAC study was funded by the European Commission (project QLK2-CT-2001-00915). F.M. MacKenzie was supported by the European Study Group on Antibiotic Policies to write this manuscript

Universal screening for meticillin-resistant Staphylococcus aureus : interim results from the NHS Scotland pathfinder project

Following recommendations from a Health Technology Assessment (HTA), a prospective cohort study of meticillin-resistant Staphylococcus aureus (MRSA) screening of all admissions (N = 29 690) to six acute hospitals in three regions in Scotland indicated that 7.5% of patientswere colonised on admission to hospital. Factors associated with colonisation included re-admission, specialty of admission (highest in nephrology, care of the elderly, dermatology and vascular surgery), increasing age, and the source of admission (care home or other hospital). Three percent of all those who were identified as colonised developed hospital-associated MRSA infection, compared with only 0.1% of those not colonised. Specialtieswith a high rate of colonisation on admission also had higher rates of MRSA infection. Very few patients refused screening (11 patients, 0.03%) or had treatment deferred (14 patients, 0.05%). Several organisational issues were identified, including difficulties in achieving complete uptake of screening (88%) or decolonisation (41%); the latter was largely due to short duration of stay and turnaround time for test results. Patient movement resulted in a decision to decontaminate all positive patients rather than just those in high risk specialties as proposed by the HTA. Issues also included a lack of isolation facilities to manage patients with MRSA. The study raises significant concerns about the contribution of decolonisation to reducing risks in hospital due to short duration of stay, and reinforces the central role of infection control precautions. Further study is required before the HTA model can be re-run and conclusions redrawn on the cost and clinical effectiveness of universal MRSA screening

Systematic review of antimicrobial drug prescribing in hospitals.

Prudent antibiotic prescribing to hospital inpatients has the potential to reduce the incidences of antimicrobial resistance and healthcare-associated infection. We reviewed the literature from January 1980 to November 2003 to identify rigorous evaluations of interventions to improve hospital antibiotic prescribing. We identified 66 studies with interpretable data of which 16 reported 20 microbiological outcomes: Gram negative resistant bacteria (GNRB), 10 studies; Clostridium difficile associated diarrhoea (CDAD), 5 studies; vancomycin resistant enterococci (VRE), 3 studies and methicillin resistant Staphylococcus aureus (MRSA), 2 studies. Four studies provide good evidence that the intervention changed microbial outcomes with low risk of alternative explanations, eight studies provide less convincing evidence and four studies were negative. The strongest and most consistent evidence was for CDAD but we were able to analyse only the immediate impact of interventions because of nonstandardised durations of follow up. The ability to compare results of studies could be substantially improved by standardising methodology and reporting

Optimizing antibiotic therapy-the Aberdeen experience

ObjectiveTo study the quality and continuity of treatment in the Acute Medicines Assessment Unit (AMAU) with regard to empirical prescription of antibiotics, mode of administration, adherence to ward antibiotic policy, as well as collection, awareness and utilization of microbiological investigations.MethodsA prospective study over a 3-month period at the AMAU, Aberdeen Royal Infirmary (ARI), a teaching hospital in north-eastern Scotland, was performed. The study included all patients started on empirical antibiotics on admission to the AMAU and followed up until their discharge.ResultsOf 1303 patients admitted, 221 (17%) were started on empirical antibiotics. This was in accordance with hospital antibiotic policy in 52% of cases. Appropriate specimens were taken from 77% of patients. Culture results showed that 29% (n = 65) of the patients had clinically significant growth of organisms. Of the 65 patients with clinically significant culture results, 49% (n = 32) were on an inappropriate empirical regimen. In 55%, the medication was not changed to a more appropriate antibiotic. In 72% of the patients with a negative culture, the culture report had no obvious effect on the duration or type of antibiotic being administered. Intravenous antibiotics were used in 60% of patients.ConclusionThis study demonstrates a significant overuse of antibiotics, especially intravenous forms, despite a paucity of positive sepsis parameters and chest X-ray findings in these patients The duration of treatment could be shortened and an early switch policy introduced if culture results and sepsis profiles were taken into consideration, as there was a large number of unproven infections. Suggestions are made about how these improvements in prescribing could be made within the current administrative set-up of AMAUs

Spinor condensates and light scattering from Bose-Einstein condensates

These notes discuss two aspects of the physics of atomic Bose-Einstein condensates: optical properties and spinor condensates. The first topic includes light scattering experiments which probe the excitations of a condensate in both the free-particle and phonon regime. At higher light intensity, a new form of superradiance and phase-coherent matter wave amplification were observed. We also discuss properties of spinor condensates and describe studies of ground--state spin domain structures and dynamical studies which revealed metastable excited states and quantum tunneling.Comment: 58 pages, 33 figures, to appear in Proceedings of Les Houches 1999 Summer School, Session LXXI

The evolution of language: a comparative review

For many years the evolution of language has been seen as a disreputable topic, mired in fanciful &quot;just so stories&quot; about language origins. However, in the last decade a new synthesis of modern linguistics, cognitive neuroscience and neo-Darwinian evolutionary theory has begun to make important contributions to our understanding of the biology and evolution of language. I review some of this recent progress, focusing on the value of the comparative method, which uses data from animal species to draw inferences about language evolution. Discussing speech first, I show how data concerning a wide variety of species, from monkeys to birds, can increase our understanding of the anatomical and neural mechanisms underlying human spoken language, and how bird and whale song provide insights into the ultimate evolutionary function of language. I discuss the ‘‘descended larynx’ ’ of humans, a peculiar adaptation for speech that has received much attention in the past, which despite earlier claims is not uniquely human. Then I will turn to the neural mechanisms underlying spoken language, pointing out the difficulties animals apparently experience in perceiving hierarchical structure in sounds, and stressing the importance of vocal imitation in the evolution of a spoken language. Turning to ultimate function, I suggest that communication among kin (especially between parents and offspring) played a crucial but neglected role in driving language evolution. Finally, I briefly discuss phylogeny, discussing hypotheses that offer plausible routes to human language from a non-linguistic chimp-like ancestor. I conclude that comparative data from living animals will be key to developing a richer, more interdisciplinary understanding of our most distinctively human trait: language