Nonlinear Quantum Dynamics

The vast majority of the literature dealing with quantum dynamics is concerned with linear evolution of the wave function or the density matrix. A complete dynamical description requires a full understanding of the evolution of measured quantum systems, necessary to explain actual experimental results. The dynamics of such systems is intrinsically nonlinear even at the level of distribution functions, both classically as well as quantum mechanically. Aside from being physically more complete, this treatment reveals the existence of dynamical regimes, such as chaos, that have no counterpart in the linear case. Here, we present a short introductory review of some of these aspects, with a few illustrative results and examples.Comment: 13 pages, 3 figures, invited talk at the NATO Advanced Workshop, "Nonlinear Dynamics and Fundamental Interactions," (October, 2004, Tashkent

Feedback cooling of a nanomechanical resonator

Cooled, low-loss nanomechanical resonators offer the prospect of directly observing the quantum dynamics of mesoscopic systems. However, the present state of the art requires cooling down to the milliKelvin regime in order to observe quantum effects. Here we present an active feedback strategy based on continuous observation of the resonator position for the purpose of obtaining these low temperatures. In addition, we apply this to an experimentally realizable configuration, where the position monitoring is carried out by a single-electron transistor. Our estimates indicate that with current technology this technique is likely to bring the required low temperatures within reach.Comment: 10 pages, RevTex4, 4 color eps figure

Design-time performance testing

Software designers make decisions between alternate approaches early in the development of a software application and these decisions can be difficult to change later. Designers make these decisions based on estimates of how alternatives affect software qualities. One software quality that can be difficult to predict is performance, that is, the efficient use of resources in the system. It is particularly challenging to estimate the performance of large, interconnected software systems composed of components. With the proliferation of class libraries, middle-ware systems, web services, and third party components, many software projects rely on third party services to meet their requirements. Often choosing between services involves considering both the functionality and performance of the services. To help software developers compare their designs and third-party services, I propose using performance prototypes of alternatives and test suites to estimate performance trade-offs early in the development cycle, a process called Design-Time Performance Testing (DTPT). Providing software designers with performance evidence based on prototypes will allow designers to make informed decisions regarding performance trade-offs. To show how DTPT can help inform real design decisions. In particular: a process for DTPT, a framework implementation written in Java, and experiments to verify and validate the process and implementation. The implemented framework assists when designing, running, and documenting performance test suites, allowing designers to make accurate comparisons between alternate approaches. Performance metrics are captured by instrumenting and running prototypes. This thesis describes the process and framework for gathering software performance estimates at design-time using prototypes and test suites

School-age effects of the newborn individualized developmental care and assessment program for preterm infants with intrauterine growth restriction: preliminary findings

Background: The experience in the newborn intensive care nursery results in premature infants’ neurobehavioral and neurophysiological dysfunction and poorer brain structure. Preterms with severe intrauterine growth restriction are doubly jeopardized given their compromised brains. The Newborn Individualized Developmental Care and Assessment Program improved outcome at early school-age for preterms with appropriate intrauterine growth. It also showed effectiveness to nine months for preterms with intrauterine growth restriction. The current study tested effectiveness into school-age for preterms with intrauterine growth restriction regarding executive function (EF), electrophysiology (EEG) and neurostructure (MRI). Methods: Twenty-three 9-year-old former growth-restricted preterms, randomized at birth to standard care (14 controls) or to the Newborn Individualized Developmental Care and Assessment Program (9 experimentals) were assessed with standardized measures of cognition, achievement, executive function, electroencephalography, and magnetic resonance imaging. The participating children were comparable to those lost to follow-up, and the controls to the experimentals, in terms of newborn background health and demographics. All outcome measures were corrected for mother’s intelligence. Analysis techniques included two-group analysis of variance and stepwise discriminate analysis for the outcome measures, Wilks’ lambda and jackknifed classification to ascertain two-group classification success per and across domains; canonical correlation analysis to explore relationships among neuropsychological, electrophysiological and neurostructural domains at school-age, and from the newborn period to school-age. Results: Controls and experimentals were comparable in age at testing, anthropometric and health parameters, and in cognitive and achievement scores. Experimentals scored better in executive function, spectral coherence, and cerebellar volumes. Furthermore, executive function, spectral coherence and brain structural measures discriminated controls from experimentals. Executive function correlated with coherence and brain structure measures, and with newborn-period neurobehavioral assessment. Conclusion: The intervention in the intensive care nursery improved executive function as well as spectral coherence between occipital and frontal as well as parietal regions. The experimentals’ cerebella were significantly larger than the controls’. These results, while preliminary, point to the possibility of long-term brain improvement even of intrauterine growth compromised preterms if individualized intervention begins with admission to the NICU and extends throughout transition home. Larger sample replications are required in order to confirm these results

NIDCAP improves brain function and structure in preterm infants with severe intrauterine growth restriction

Objective: The effect of NIDCAP (Newborn Individualized Developmental Care and Assessment Program) was examined on the neurobehavioral, electrophysiological and neurostructural development of preterm infants with severe intrauterine growth restriction (IUGR). Study Design: A total of 30 infants, 27–33 weeks gestation, were randomized to control (C; N=17) or NIDCAP/experimental (E; N=13) care. Baseline health and demographics were assessed at intake; electroencephalography (EEG) and magnetic resonance imaging (MRI) at 35 and 42 weeks postmenstrual age; and health, growth and neurobehavior at 42 weeks and 9 months corrected age (9 months). Results: C and E infants were comparable in health and demographics at baseline. At follow-up, E infants were healthier, showed significantly improved brain development and better neurobehavior. Neurobehavior, EEG and MRI discriminated between C and E infants. Neurobehavior at 42 weeks correlated with EEG and MRI at 42 weeks and neurobehavior at 9 months. Conclusion: NIDCAP significantly improved IUGR preterm infants' neurobehavior, electrophysiology and brain structure. Longer-term outcome assessment and larger samples are recommended

The construction and evaluation of a device for mechanomyography in anaesthetized Göttingen minipigs

OBJECTIVE: To devise a method for assessing evoked muscle strength on nerve stimulation [mechanomyography (MMG)] in the anaesthetized minipig. STUDY DESIGN: Prospective observational. ANIMALS: Sixty male Göttingen minipigs weighing 10.5–26.0 kg. METHODS: After cadaveric studies, a limb fixation device was constructed which allowed the twitch responses of the pelvic limb digital extensor muscles to be measured by force-displacement transduction in response to supramaximal train-of-four (TOF) stimulation of the common peroneal nerve. The device was tested in 60 minipigs weighing 10.5–26.0 kg positioned in dorsal recumbency. RESULTS: The technique recorded the MMG of the common peroneal-pelvic limb digital extensor nerve-muscle unit for up to 12 hours during which twitch height remained constant in 18 animals in which single twitch duration was <300–500 ms. In 42, in which twitch duration was >300–500 ms, 2 Hz nerve stimulation caused progressive baseline elevation (reverse fade) necessitating a modified signal capture method for TOF ratio (TOFR) computation. However, T1 was unaffected. The mean (range) of the TOFR in pigs with reverse fade was 1.2 (1.1–1.3). CONCLUSIONS AND CLINICAL RELEVANCE: The technique allowed MMG recording in unparalysed pigs in response to TOF nerve stimulation and revealed a hitherto unreported complication of MMG monitoring using TOF in animals: reverse fade. This complicated TOFR calculation

How players exploit variability and regularity of game actions in female volleyball teams

Variability analysis has been used to understand how competitive constraints shape different behaviours in team sports. In this study, we analysed and compared variability of tactical performance indices in players within complex I at two different competitive levels in volleyball. We also examined whether variability was influenced by set type and period. Eight matches from the 2012 Olympics competition and from the Portuguese national league in the 2014–2015 season were analysed (1496 rallies). Variability of setting conditions, attack zone, attack tempo and block opposition was assessed using Shannon entropy measures. Magnitude-based inferences were used to analyse the practical significance of compared values of selected variables. Results showed differences between elite and national teams for all variables, which were co-adapted to the competitive constraints of set type and set periods. Elite teams exploited system stability in setting conditions and block opposition, but greater unpredictability in zone and tempo of attack. These findings suggest that uncertainty in attacking actions was a key factor that could only be achieved with greater performance stability in other game actions. Data suggested how coaches could help setters develop the capacity to play at faster tempos, diversifying attack zones, especially at critical moments in competition

Higher D or Li: Probes of Physics beyond the Standard Model

Standard Big Bang Nucleosynthesis at the baryon density determined by the microwave anisotropy spectrum predicts an excess of \li7 compared to observations by a factor of 4-5. In contrast, BBN predictions for D/H are somewhat below (but within ~2 \sigma) of the weighted mean of observationally determined values from quasar absorption systems. Solutions to the \li7 problem which alter the nuclear processes during or subsequent to BBN, often lead to a significant increase in the deuterium abundance consistent with the highest values of D/H seen in absorption systems. Furthermore, the observed D/H abundances show considerable dispersion. Here, we argue that those systems with D/H \simeq 4 \times 10^{-5} may be more representative of the primordial abundance and as a consequence, those systems with lower D/H would necessarily have been subject to local processes of deuterium destruction. This can be accounted for by models of cosmic chemical evolution able to destroy in situ Deuterium due to the fragility of this isotope.Comment: 22 pages, 8 figure

The Rise of the Resilient Local Authority?

The term resilience is increasingly being utilised within the study of public policy to depict how individuals, communities and organisations can adapt, cope, and ‘bounce back’ when faced with external shocks such as climate change, economic recession and cuts in public expenditure. In focussing on the local dimensions of the resilience debate, this article argues that the term can provide useful insights into how the challenges facing local authorities in the UK can be reformulated and reinterpreted. The article also distinguishes between resilience as ‘recovery’ and resilience as ‘transformation’, with the latter's focus on ‘bouncing forward’ from external shocks seen as offering a more radical framework within which the opportunities for local innovation and creativity can be assessed and explained. While also acknowledging some of the weaknesses of the resilience debate, the dangers of conceptual ‘stretching’, and the extent of local vulnerabilities, the article highlights a range of examples where local authorities – and crucially, local communities – have enhanced their adaptive capacity, within existing powers and responsibilities. From this viewpoint, some of the barriers to the development of resilient local government are not insurmountable, and can be overcome by ‘digging deep’ to draw upon existing resources and capabilities, promoting a strategic approach to risk, exhibiting greater ambition and imagination, and creating space for local communities to develop their own resilience

The properties of discs around planets and brown dwarfs as evidence for disc fragmentation

Direct imaging searches have revealed many very low mass objects, including a small number of planetary-mass objects, as wide-orbit companions to young stars. The formation mechanism of these objects remains uncertain. In this paper, we present the predictions of the disc fragmentation model regarding the properties of the discs around such low-mass objects. We find that the discs around objects that have formed by fragmentation in discs hosted by Sun-like stars (referred to as parent discs and parent stars) are more massive than expected from the M disc-M∗relation (which is derived for stars with masses M∗>0.2M). Accordingly, the accretion rates on to these objects are also higher than expected from thė M∗−M∗relation. Moreover, there is no significant correlation between the mass of the brown dwarf or planet with the mass of its disc nor with the accretion rate from the disc on to it. The discs around objects that form by disc fragmentation have larger than expected masses as they accrete gas from the disc of their parent star during the first few kyr after they form. The amount of gas that they accrete and therefore their mass depend on how they move in their parent disc and how they interact with it. Observations of disc masses and accretion rates on to very low mass objectsareconsistentwiththepredictionsofthediscfragmentationmodel.Futureobservations (e.g. by Atacama Large Millimeter/submillimeter Array) of disc masses and accretion rates on to substellar objects that have even lower masses (young planets and young, low-mass brown dwarfs), where the scaling relations predicted by the disc fragmentation model diverge significantly from the corresponding relations established for higher mass stars, will test the predictions of this model