Gradual Drift Research Articles

Behavior of Inclusions in Process of Solid Growth During Solidification of Fe-0.15C-0.8Mn Steel

AbstractThe behavior of inclusions in the process of δ-phase growth during the solidification of Fe-0. 15C-0. 8Mn steel was in-situ observed using a high-temperature confocal scanning laser microscope (HTCSLM). The results show that inclusions arrive the S/L (solid/liquid) interface by way of direct impact or gradual drift, when the cell spacing is approximately equal to 177 μm during the growth of cellular δ-phase. The inclusions easily stay at the positions of trailing vortex formed by the circumferential motion of molten steel around δ-phase. Some inclusions reaching the S/L interface are captured by the solid-phase. Some of them move along the normal direction of the S/L interface because of pushing of solid-phase, and the others get away from the S/L interface after being pushed for a distance. The faster the growth rates of the solid-phase are, the easier the inclusions are captured by the S/L interface. The slower the growth rates of the solid-phase are, the easier the inclusions move with the S/L interface.

Ventilatory long‐term facilitation following acute intermittent or continuous hypoxaemia in awake humans: the role of carotid chemoreceptors and ventilatory drift to sustained hypercapnia

In awake humans, acute intermittent hypoxaemia (IH) causes a sustained increase in ventilation upon reoxygenation, known as ventilatory long‐term facilitation (vLTF), but only if combined with mild hypercapnia. It is not known if mild hypercapnia also unmasks vLTF following continuous hypoxia (CH). Carotid chemoreceptor (CC) sensitisation has been proposed as a mechanism for vLTF. We hypothesised that silencing the CC with 100% O2 would transiently abolish vLTF.12 males undertook 3 trials. Mild hypercapnia was maintained in all trials and one minute exposures to 100% O2 occurred at baseline and recovery. Trials differed only in their hypoxic exposure; Trial 1‐Acute IH, Trial 2‐Acute CH, Trial 3‐Euoxia. Ventilation in Trial 1 and 2 increased from baseline to recovery (T1: 20.1 ± 1.1 vs. 25.1 ± 1.6, T2: 20.0 ± 1.2 vs. 25.1 ± 1.4 L/min).Ventilation also increased in Trial 3 but to a lesser extent (19.8 ± 1.17 vs. 22.4 ± 1.84 L/min). Ventilation during 100% O2 increased from baseline to recovery in all trials (T1: 17.1 ± 1.2 vs. 21.8 ± 1.6, T2: 18.0 ± 1.5 vs. 22.5 ± 1.5, T3: 17.6 ± 1.4 vs. 20.2 ± 2.1).In awake humans, during mild hypercapnia, CH induces a similar magnitude of vLTF as IH. However, a gradual positive drift in ventilation to mild hypercapnia accounts for ~50% of the vLTF. Silencing of the CC with 100% O2 exposure does not transiently abolish vLTF following acute IH or CH, suggesting CC sensitisation may not mediate vLTF.

Recrudescent wave of pandemic A/H1N1 influenza in Mexico, Winter 2011-2012: Age shift and severity.

BackgroundA substantial recrudescent wave of pandemic influenza A/H1N1 that began in December 2011 is ongoing and has not yet peaked in Mexico, following a 2-year period of sporadic transmission. Mexico previously experienced three pandemic waves of A/H1N1 in 2009, associated with higher excess mortality rates than those reported in other countries, and prompting a large influenza vaccination campaign. Here we describe changes in the epidemiological patterns of the ongoing 4th pandemic wave in 2011-12, relative to the earlier waves in 2009. The analysis is intended to guide public health intervention strategies in near real time.MethodsWe analyzed demographic and geographic data on all hospitalizations with acute respiratory infection (ARI) and laboratory-confirmed A/H1N1 influenza, and inpatient deaths, from a large prospective surveillance system maintained by the Mexican Social Security medical system during 01-April 2009 to 10-Feb 2012. We characterized the age and regional patterns of A/H1N1-positive hospitalizations and inpatient-deaths relative to the 2009 A/H1N1 influenza pandemic. We also estimated the reproduction number (R) based on the growth rate of the daily case incidence by date of symptoms onset.ResultsA total of 5,795 ARI hospitalizations and 186 inpatient-deaths (3.2%) were reported between 01-December 2011 and 10-February 2012 (685 A/H1N1-positive inpatients and 75 A/H1N1-positive deaths). The nationwide peak of daily ARI hospitalizations in early 2012 has already exceeded the peak of ARI hospitalizations observed during the major fall pandemic wave in 2009. The mean age was 34.3 y (SD=21.3) among A/H1N1 inpatients and 43.5 y (SD=21) among A/H1N1 deaths in 2011-12. The proportion of laboratory-confirmed A/H1N1 hospitalizations and deaths was higher among seniors >=60 years of age (Chi-square test P<0.001) and lower among younger age groups (Chi-square test, P<0.03) for the 2011-2012 pandemic wave, compared to the earlier waves in 2009. The reproduction number of the winter 2011-12 wave in central Mexico was estimated at 1.2-1.3, similar to that reported for the fall 2009 wave, but lower than that of spring 2009. ConclusionsWe have documented a substantial and ongoing increase in the number of ARI hospitalizations during the period December 2011-February 2012 and an older age distribution of laboratory-confirmed A/H1N1 influenza hospitalizations and deaths, relative to 2009 A/H1N1 pandemic patterns. The gradual change in the age distribution of A/H1N1 infections in the post-pandemic period is reminiscent of historical pandemics and indicates either a gradual drift in the A/H1N1 virus, and/or a build-up of immunity among younger populations.

Crosstalk in multicore fibers with randomness: gradual drift vs short-length variations

Random perturbations play an important role in the crosstalk of multicore fibers, and can be captured by statistical coupled-mode calculations. In this approach, phase matching contributes a multiplicative factor to the average crosstalk, depending on the perturbation statistics and any intentional heterogeneity of neighboring cores. The impact of perturbations is shown to be qualitatively different depending on whether they are gradually varying, or have short-length (centimeter-scale) variations. This insight implies a novel crosstalk suppression strategy: fast modulation of a bend perturbation by spinning the fiber can disrupt the bend-induced phase matching.

Dynamic Style Analysis and Applications

We analyze the shortcomings of existing multi-factor models based on portfolio performance data in detecting investment portfolio dynamics such as gradual style drift or rapid changes in strategy. We then lay the groundwork for a new approach, which we call Dynamic Style Analysis (DSA), representing a time-series multi-factor portfolio analysis model. The major concepts of the new methodology are gradually introduced and applied to analyses of both model portfolios and well-known US equity mutual funds. By comparing publicly available holdings data with results obtained with DSA, we demonstrate both the superiority of the new model and its remarkable accuracy in detecting portfolio dynamics. We also address issues such as the computational complexity of DSA and its practical applications in the areas of risk management, performance measurement and investment research. One of the major applications of the new methodology lies in hedge fund due diligence and risk monitoring, where the importance of uncovering and controlling hidden factor dynamics is especially valuable given the limited transparency of hedge funds.

Using unsupervised incremental learning to cope with gradual concept drift

Current computational approach to incremental learning requires a constant stream of labelled data to cope with gradual environmental changes known as concept drift. This paper examines a case where labelled data are unavailable. Inspired by the performance of the human visual system, capable of adjusting its concepts using unlabelled stimuli, we introduce a variant to an unsupervised competitive learning algorithm known as the Leader Follower (LF). This variant can adjust pre-learned concepts to environmental changes using unlabelled data samples. We motivate the needed change in the existing LF algorithm and compare between two variants to enable the accumulation of environmental changes when facing unbalanced sample ratio.

Online Appearance Model Learning and Generation for Adaptive Visual Tracking

Several adaptive visual tracking algorithms have been recently proposed to capture the varying appearance of target. However, adaptability may also result in the problem of gradual drift, especially when the target appearance changes drastically. This paper gives some theoretical principles for online learning of target model, and then presents a novel adaptive tracking algorithm which is able to effectively cope with drastic variations in target appearance and resist gradual drift. Once target is localized in each frame, the patches sampled from target observation are first classified into foreground and background using an effective classifier. Then the adaptive, pure and time-continuous target model is extracted online through two processes: absorption process and rejection process, through which only the reliable features with high separability are absorbed in the new target model, while the “dangerous” features which may cause interfusion of background patterns are rejected. To minimize the influence of background and keep the temporal continuity of target model, two collaborative models dominant model and continuous model are designed. The proposed learning and generation mechanisms of target model are finally embedded in an adaptive tracking system. Experimental results demonstrate the robust performance of the proposed algorithm under challenging conditions.

Self-Adaptive Induction of Regression Trees

A new algorithm for incremental construction of binary regression trees is presented. This algorithm, called SAIRT, adapts the induced model when facing data streams involving unknown dynamics, like gradual and abrupt function drift, changes in certain regions of the function, noise, and virtual drift. It also handles both symbolic and numeric attributes. The proposed algorithm can automatically adapt its internal parameters and model structure to obtain new patterns, depending on the current dynamics of the data stream. SAIRT can monitor the usefulness of nodes and can forget examples from selected regions, storing the remaining ones in local windows associated to the leaves of the tree. On these conditions, current regression methods need a careful configuration depending on the dynamics of the problem. Experimentation suggests that the proposed algorithm obtains better results than current algorithms when dealing with data streams that involve changes with different speeds, noise levels, sampling distribution of examples, and partial or complete changes of the underlying function.

The baseline pressure of intracranial pressure (ICP) sensors can be altered by electrostatic discharges

BackgroundThe monitoring of intracranial pressure (ICP) has a crucial role in the surveillance of patients with brain injury. During long-term monitoring of ICP, we have seen spontaneous shifts in baseline pressure (ICP sensor zero point), which are of technical and not physiological origin. The aim of the present study was to explore whether or not baseline pressures of ICP sensors can be affected by electrostatics discharges (ESD's), when ESD's are delivered at clinically relevant magnitudes.MethodsWe performed bench-testing of a set of commercial ICP sensors. In our experimental setup, the ICP sensor was placed in a container with 0.9% NaCl solution. A test person was charged 0.5 - 10 kV, and then delivered ESD's to the sensor by touching a metal rod that was located in the container. The continuous pressure signals were recorded continuously before/after the ESD's, and the pressure readings were stored digitally using a computerized systemResultsA total of 57 sensors were tested, including 25 Codman ICP sensors and 32 Raumedic sensors. When charging the test person in the range 0.5-10 kV, typically ESD's in the range 0.5 - 5 kV peak pulse were delivered to the ICP sensor. Alterations in baseline pressure ≥ 2 mmHg was seen in 24 of 25 (96%) Codman sensors and in 17 of 32 (53%) Raumedic sensors. Lasting changes in baseline pressure > 10 mmHg that in the clinical setting would affect patient management, were seen frequently for both sensor types. The changes in baseline pressure were either characterized by sudden shifts or gradual drifts in baseline pressure.ConclusionsThe baseline pressures of commercial solid ICP sensors can be altered by ESD's at discharge magnitudes that are clinically relevant. Shifts in baseline pressure change the ICP levels visualised to the physician on the monitor screen, and thereby reveal wrong ICP values, which likely represent a severe risk to the patient.

Dynamic financial distress prediction using instance selection for the disposal of concept drift

Prior studies of financial distress prediction (FDP) all focus on static modeling and ignore whether the model is still suitable with time passing on. This paper devotes to the first investigation on what the concept of financial distress concept drift (FDCD) is, whether FDCD exists and how to dispose FDCD. We construct a dynamic FDP modeling based on instance selection for the disposal of FDCD. Dynamic FDP consists of instance selection, FDP modeling and future prediction. Instance selection methods including full memory window, no memory window, window of fixed size, window of adaptable size, and batch selection are used to tackle FDCD. For feature selection, we construct a wrapper by integrating forward and backward selections on Mahalanobis distance. Empirical results indicate that gradual and constant virtual concept drift does exist in FDP, and dynamic FDP models perform much better than static models. Meanwhile, window of fixed size and batch selection are more suitable for Chinese listed companies’ dynamic FDP.

Traces of neo-Calvinism in France and Italy

This article deals with the history of the neo-Calvinist movement in France and Italy. The efforts of the Dutch Reformational movement to communicate with French (mainly reformed) Christians are highlighted. A brief overview of the achievements of the few French scholars involved in this development is sketched and their publications are mentioned, together with a few conferences and organisations. Neo-Calvinism reached Italy as well, via the input of French lecturers and publications. The few developments of neo-Calvinism in Italy are recorded as well. Also, the gradual drift towards vantilian and reconstructionist positions (in both countries) is detected and discussed. An evaluation of these developments is provided, together with a few final considerations and questions which should help learning lessons from the past and preparing better strategies for the future.

A dynamic nonlinear relationship between the static and pulsatile components of intracranial pressure in patients with subarachnoid hemorrhage

In the search for optimal monitoring and predictive tools in neurocritical care, the relationship of the pulsatile component of intracranial pressure (ICP) and the pressure itself has long been of great interest. Higher pressure often correlates with a higher pulsatile response to the heartbeat, interpreted as a type of compliance curve. Various mathematical approaches have been used, but regardless of the formula used, it is implicitly assumed that a reproducible curve exists. The authors investigated the stability of the correlation between static and pulsatile ICPs in patients with subarachnoid hemorrhage (SAH) who were observed for several hours by using data sets large enough to allow such calculations to be made. The ICP recordings were obtained in 39 patients with SAH and were parsed into 6-second time windows (1,998,944 windows in 197 recordings). The ICP parameters were computed for each window as follows: static ICP was defined as the mean ICP, and pulsatile ICP was characterized by mean ICP wave amplitude, rise time, and rise time coefficient. The mean ICP and ICP wave amplitudes were simultaneously high or low (the expected correlation) in only approximately 60% of observations. Furthermore, static and pulsatile ICP correlated well only over short intervals; the degree of correlation weakened over periods of hours and was inconsistent across patients and within individual patients over time. Decorrelation originated with abrupt shifting and gradual drifting of mean ICP and ICP wave amplitude over several hours. The relationship between the static and pulsatile components of ICPs changes over time. It evolves, even in individual patients, over a number of hours. This can be one reason the observation of high pulsatile ICP (indicative of reduced intracranial compliance) despite normal mean ICP that is seen in some patients with SAH. The meaning and potential clinical usefulness of such changes in the curves is uncertain, but it implies that clinical events result not only from moving further out on a compliance curve; in practice, the curve, and the biological system that underlies the curve, may itself change.

Influenza A Gradual and Epochal Evolution: Insights from Simple Models

The recurrence of influenza A epidemics has originally been explained by a “continuous antigenic drift” scenario. Recently, it has been shown that if genetic drift is gradual, the evolution of influenza A main antigen, the haemagglutinin, is punctuated. As a consequence, it has been suggested that influenza A dynamics at the population level should be approximated by a serial model. Here, simple models are used to test whether a serial model requires gradual antigenic drift within groups of strains with the same antigenic properties (antigenic clusters). We compare the effect of status based and history based frameworks and the influence of reduced susceptibility and infectivity assumptions on the transient dynamics of antigenic clusters. Our results reveal that the replacement of a resident antigenic cluster by a mutant cluster, as observed in data, is reproduced only by the status based model integrating the reduced infectivity assumption. This combination of assumptions is useful to overcome the otherwise extremely high model dimensionality of models incorporating many strains, but relies on a biological hypothesis not obviously satisfied. Our findings finally suggest the dynamical importance of gradual antigenic drift even in the presence of punctuated immune escape. A more regular renewal of susceptible pool than the one implemented in a serial model should be part of a minimal theory for influenza at the population level.

Ecology of harp seal (Phoca groenlandica) pups on ices in the White Sea

The harp seal ( Phoca groenlandica ) is the most abundant species of the true seals inhabiting the northern hemisphere. Depending on breeding area location, three populations (Newfoundland, White-Sea, and Jan Mayen) of harp seals are distinguished [1, 2]. Owing to the high total abundance, the harp seal remains the key commercial animal whose herds in Russia, Norway, Canada, and Greenland (Denmark) are extensively harvested every year. The current size of the White-Sea population of harp seals is 1.8‐2 million animals [3]. The range of the harp seal is wide: during summer migrations, the seals inhabit the Barents Sea and other Northern Atlantic areas and occur in the Kara Sea [4‐6]. In winter, harp seals congregate in the White Sea for mating and breeding; they live in large herds on ice floes from December to May. The abundance of offspring annually born in spring on ice reaches more than 300 thousand pups [7]. The hydrometeorological conditions of the White Sea ensure gradual drift of ice floes with adult seals and pups from the central areas of the sea to the northeast areas and then to the Barents Sea. Harp seal pups live in the White Sea from February to May. Postnatal development of pups (suckling, moult, and transition to independent nutrition) takes place on drifting ice floes; at this time, young seals adapt to leaving in water. The short breeding (pupping) period, high breeding rate, and sufficient fatness of pups at the end of the suckling period are the key adaptation components. However, published data regarding these issues are scanty. It is known that body weight of pups increases after birth, the suckling period lasts for two weeks, and the postembryonic moult lasts for 25‐ 30 days [8, 9]. In the White Sea, the pupping period of harp seals continues for approximately four weeks [8‐11]. The pupping period of harp seals in 1925‐1935 began

Yeah! Yeah! Yeah!: The Beatles, Beatlemania, and the Music That Changed the World (review)

Reviewed by: My Life as a Rhombus Karen Coats Johnson, Varian My Life as a Rhombus. Flux, 2008 [312p] Paper ed. ISBN 978-0-7387-1160-7$9.95 Reviewed from galleys R Gr. 9-12 What Elizabeth Partridge did for John Lennon in John Lennon: All I Want Is the Truth (BCCB 12/05), Spitz does for the Fab Four as a whole: provide a compelling, highly readable biography and offer convincing proof that these rockers changed the world as we know it and gave an entire generation a soundtrack that grew up as they did. From the band's early days as the Quarrymen, through excruciating growing pains and mad popularity, to gradual drift and breakdown, the author sets the group in its contexts, giving equal weight to each member and highlighting the dynamics of their various relationships. Spitz, who has previously biographized the Beatles and other musicians for adults, here downplays but doesn't completely eliminate references to their drug use; he does, however, apply a liberal dose of whitewash to the band's sexploits, choosing to chronicle only those relationships that ultimately mattered in some lasting way. What he does particularly well in this offering is to emphasize the prisonhouse of fame that constantly threatened to crush the group and show the innovations the group introduced, such as the inclusion of lyrics in liner notes, that contemporary audiences take for granted. Generous use of photographs reinforces the antic nature of the group and conveys how much fun they must have had in the early days, and text inserts provide additional tidbits of information that broaden the context. Interesting anecdotes about song origins and lots of quotations from the Beatles themselves demystify the magical mystery tour of legends that haunts the legacy of the group; readers will end up feeling very cool and in the know when they finish. U.S. discography, selected bibliography, and index are included. Copyright © 2008 The Board of Trustees of the University of Illinois

Evolution in concepts concerning the mechanism of plasticity in solid polymers after the 1950s

The evolution of fundamental concepts concerning the mechanisms of plastic deformation in solid polymers, crystals (both glassy and semicrystalline) over the recent five decades has been reviewed. The most effective approach to the description of cold plastic deformation is a gradual drift away from the chain straightening mechanism as a limiting kinetic stage of the process (or, in other words, from the picture of the rubbery character of deformation) to concepts that are characteristic of the deformation physics of nonpolymer solids, primarily metals. Various nonpolymeric mechanisms, such as nucleation and growth of dislocations in polymer crystals, formation and evolution of short-scale undeveloped shear transformations in glasses, and mutual deformation constraints of amorphous and crystalline phases in semicrystalline polymers, are introduced in polymer science. An analysis of the published data shows that deformation in solid polymers is undoubtedly accompanied by chain straightening, but, in most cases, this process does not control the overall kinetics of plasticity, at least at small and moderate strains. In glassy polymers, conformational chain rearrangements are not going directly but proceed as shape fitting of macromolecule coils to short-scale shear transformations that serve as active sites of plasticity. The chain character and flexibility of macromolecules have a slight effect on the nucleation of the above transformations. The development of local shear at the early stages of loading is the thorniest stage of deformation. Problems concerning the joint development of polymer and nonpolymer processes during deformation of macromolecular solids and the specific features related to the polymer structure of macromolecules are discussed.

A Feed-Forward/Feedback Run-to-Run Control of a Mixed Product Process: Simulation and Experimental Studies

Run-to-run (RtR) control is an important quality assurance method for batch-based manufacturing process. Usually, products of different grades are produced on a tool that will experience gradual drift between maintenance cycles. A feed-forward/feedback RtR control strategy that compensates this drift for all products manufactured on this tool was proposed. This and other RtR control schemes were analyzed and validated by simulation and experimentally using a bench scale reactor that produces silica particles with different diameters by a sol-gel process. A simple EWMA (exponentially weighted moving average) RtR control scheme based on products of the same grade was found to be stable but inefficient for infrequent products. A simple EWMA RtR control scheme that attributed disturbance entirely as the effect of tool drift was found to be unstable. The feed-forward/feedback RtR control proposed was able to maintain stable quality by effectively utilizing information about tool changes to adjust recipes of infrequent products.

Ichthyoplankton of the eastern shelf of Sakhalin Island and its use as an environmental state indicator

Results of studying ichthyoplankton off the eastern coast of Sakhalin Island in July 2002, are presented. The spatial distribution of the eggs and larvae of almost all encountered species confirms the presence of drift along the coast with a gradual drift of passive migrants from the coast of eastern Sakhalin into the open waters. The most diverse and numerous ichthyoplankton was over the shelf zone to the north of 51°00′; the least diverse, from 50°00′ to 51°00′ N. The minimal proportion of the normally developing eggs of the wall-eyed pollack Theragra chalcogramma and the yellow-finned sole Limanda aspera dominant in catches was recorded over the oil-gas deposits located in the coastal zone of the northeastern shelf. The coincidence of stations (83%) with a high proportion of the dead eggs of these fish species can indicate a similar impact on it of environmental conditions formed in deposit areas.

How adaptive is parasite species diversity?

Has species diversity in parasites evolved as a by-product of adaptive diversification driven by competition for limited resources? Or is it a result of gradual genetic drift in isolation? One can move closer to answering these questions by evaluating the ubiquity of host switching, the key stage of adaptive diversification. Studies dealing with evolutionary role of host switching suggest that this process is extremely common in the wild, thus pointing at adaptive nature of parasite species diversity. However, most of these studies are focused on the evidence that may or may not have emerged as a consequence of host switching, – an approach potentially associated with a degree of uncertainty. After an overview of the data I am making an attempt to get a clearer view on host switching by focusing on factors that cause this phenomenon. In particular, I review theoretical work and field observations in order to identify the type of genetic host-use variance and the type of dispersal that underpin host switching. I show that host switching is likely to require generalist modifier alleles which increase the host range of individual genotypes and is likely to be promoted by wave-like patterns of dispersal. Both factors appear to be common in parasites. I conclude by outlining key areas for future research, including: (i) direct testing for divergence with gene flow, the main “footprint” of adaptive speciation; (ii) investigating the association between demography, dispersal potential and the potential to colonise novel habitats; and (iii) determining the genetic mechanisms underpinning host range variance in parasites.

Thermal inertia of near-Earth asteroids and implications for the magnitude of the Yarkovsky effect

Thermal inertia determines the temperature distribution over the surface of an asteroid and therefore governs the magnitude the Yarkovsky effect. The latter causes gradual drifting of the orbits of km-sized asteroids and plays an important role in the delivery of near-Earth asteroids (NEAs) from the main belt and in the dynamical spreading of asteroid families. At present, very little is known about the thermal inertia of asteroids in the km size range. Here we show that the average thermal inertia of a sample of NEAs in the km-size range is 200 ± 40 J m −2 s −0.5 K −1 . Furthermore, we identify a trend of increasing thermal inertia with decreasing asteroid diameter, D. This indicates that the dependence of the drift rate of the orbital semimajor axis on the size of asteroids due to the Yarkovsky effect is a more complex function than the generally adopted D −1 dependence, and that the size distribution of objects injected by Yarkovsky-driven orbital mobility into the NEA source regions is less skewed to smaller sizes than generally assumed. We discuss how this fact may help to explain the small difference in the slope of the size distribution of km-sized NEAs and main-belt asteroids.