Changes in joint stability with muscle contraction measured from transmission of mechanical vibration

A non-invasive in vivo technique was developed to evaluate changes in wrist joint stability properties induced by increased co-activation of the forearm muscles in a gripping task. Mechanical vibration at 45, 50 and 55 Hz was applied to the radial head in ten healthy volunteers. Vibrations of the styloid process of the radius and the distal end of the metacarpal bone of the index finger were measured with triaxial accelerometers. Joint stability properties were quantified by the transfer function gain between accelerations on either side of the wrist-joint. Gain was calculated with the muscles at rest and at five force levels ranging from 5% to 25% of maximum grip force (%MF). During contraction the gain was significantly greater than in control trial (0%MF) for all contractions levels at 45 and 50 Hz and a trend for 15%MF and higher at 55 Hz. Group means of contraction force and gain were significantly correlated at 45 (R-2 = 0.98) and 50 Hz (R-2 = 0.72), but not at 55 Hz (R-2 = 0.10). In conclusion, vibration transmission gain may provide a method to evaluate changes in joint stability properties. (c) 2005 Published by Elsevier Ltd.

Genome reduction in Leptospira borgpetersenii reflects limited transmission potential

Leptospirosis is one of the most common zoonotic diseases in the world, resulting in high morbidity and mortality in humans and affecting global livestock production. Most infections are caused by either Leptospira borgpetersenii or Leptospira interrogans, bacteria that vary in their distribution in nature and rely on different modes of transmission. We report the complete genomic sequences of two strains of L. borgpetersenii serovar Hardjo that have distinct phenotypes and virulence. These two strains have nearly identical genetic content, with subtle frameshift and point mutations being a common form of genetic variation. Starkly limited regions of synteny are shared between the large chromosomes of L. borgpetersenii and L. interrogans, probably the result of frequent recombination events between insertion sequences. The L. borgpetersenii genome is ≈700 kb smaller and has a lower coding density than L. interrogans, indicating it is decaying through a process of insertion sequence-mediated genome reduction. Loss of gene function is not random but is centered on impairment of environmental sensing and metabolite transport and utilization. These features distinguish L. borgpetersenii from L. interrogans, a species with minimal genetic decay and that survives extended passage in aquatic environments encountering a mammalian host. We conclude that L. borgpetersenii is evolving toward dependence on a strict host-to-host transmission cycle.

How lifetimes shape epigenotype within and across generations

Despite our detailed characterization of the human genome at the level of the primary DNA sequence, we are still far from understanding the molecular events underlying phenotypic variation. Epigenetic modifications to the DNA sequence and associated chromatin are known to regulate gene expression and, as such, are a significant contributor to phenotype. Studies of inbred mice and monozygotic twins show that variation in the epigenotype can be seen even between genetically identical individuals and that this, in some cases at least, is associated with phenotypic differences. Moreover, recent evidence suggests that the epigenome can be influenced by the environment and these changes can last a lifetime. However, we also know that epigenetic states in real-time are in continual flux and, as a result, the epigenome exhibits instability both within and across generations. We still do not understand the rules governing the establishment and maintenance of the epigenotype at any particular locus. The underlying DNA sequence itself and the sequence at unlinked loci (modifier loci) are certainly involved. Recent support for the existence of transgenerational epigenetic inheritance in mammals suggests that the epigenetic state of the locus in the previous generation may also play a role. Over the next decade, many of these processes will be better understood, heralding a greater capacity for us to correlate measurable molecular marks with phenotype and providing the opportunity for improved diagnosis and presymptomatic healthcare.

Hematozoa of teleosts from Lizard Island, Australia with some comments on their possible mode of transmission and the description of a new hemogregarine species

Little is known of the blood parasites of coral reef fishes and nothing of how they are transmitted. We examined 497 fishes from 22 families, 47 genera, and 78 species captured at Lizard Island, Australia, between May 1997 and April 2003 for hematozoa and ectoparasites. We also investigated whether gnathiid isopods might serve as potential vectors of fish hemogregarines. Fifty-eight of 124 fishes caught in March 2002 had larval gnathiid isopods, up to 80 per host fish, and these were identified experimentally to be of 2 types, Gnathia sp. A and Gnathia sp. B. Caligid copepods were also recorded but no leeches. Hematozoa, found in 68 teleosts, were broadly hemogregarines of 4 types and an infection resembling Haemohormidium. Mixed infections (hemogregarine with Haemohormidium) were also observed, but no trypanosomes were detected in blood films. The hemogregarines were identified as Haemogregarina balistapi n. sp., Haemogregarina tetraodontis, possibly Haemogregarina bigemina, and an intraleukocytic hemogregarine of uncertain status. Laboratory-reared Gnathia sp. A larvae, fed experimentally on bruslitail tangs, the latter heavily infected with the H. bigemina-like hemogregarine, contained hemogregarine gamonts and possibly young oocysts up to 3 days postfeeding, but no firm evidence that gnathiids transmit hemogregarines at Lizard Island was obtained.

Interactions between serotonergic genotype and amino acid transmitter receptor expression in human alcoholics

Serotonin can modulate the activity of neural reward pathways that are strongly implicated in mediating the effects of chronic alcohol misuse, and its treatment, in human subjects. In previous work and as discussed elsewhere at this meeting, we and others have found consistent differences in the parameters of GABA and glutamate receptors, and the expression of their component subunit transcripts and proteins, in areas of the alcoholic brain that are altered by alcoholism. We did not fi nd clear changes in GABA and glutamate transport function in such samples, but a series of microarray analyses showed consistent upregulation of the presynaptic GABA/betaine transporter SLC6A12. Microarray studies showed no signifi cant differences in the expression of transcripts associated with 5HT transmission; however, only a small number of such elements were present on the arrays. Here we partitioned GABAA and NMDA pharmacology, and subunit mRNA and protein expression, measured in samples of frontal and motor cortex obtained at autopsy from alcoholics without comorbid disease, alcoholics with liver cirrhosis, and controls, according to 5HTTLPR (SLC6A4) and 5HT1B (HTR1B) polymorphisms. We found no effect of these genotypes on the expression of GABAA receptor gene products, but there was a signifi cant mRNA Transcript X Area X Group X 5HTTLPR Interaction with NMDA subunit isoform expression measured by Real Time PCR with GAPDH normalization. Further analysis showed the effect to be selective for alcoholics with cirrhosis, to be most marked in the pathologically vulnerable frontal cortex, and to vary with subunit transcript (F2,76 = 6.545, P = 0.002). NR1 expression was most affected, followed by NR2A, with NR2B expression least altered. Pilot data suggest 5HT1B genotype may also modulate NMDA subunit expression. Interactions between amino acid and serotonin transmission may infl uence susceptibility to alcohol dependence or pathogenesis

Power generation investment opportunities evaluation: A comparison between net present value and real options approach

To evaluate an investment project in the competitive electricity market, there are several key factors that affects the project's value: the present value that the project could bring to investor, the possible future course of actions that investor has and the project's management flexibility. The traditional net present value (NPV) criteria has the ability to capture the present value of the project's future cash flow, but it fails to assess the value brought by market uncertainty and management flexibility. By contrast with NPV, the real options approach (ROA) method has the advantage to combining the uncertainty and flexibility in evaluation process. In this paper, a framework for using ROA to evaluate the generation investment opportunity has been proposed. By given a detailed case study, the proposed framework is compared with NPV and showing a different results

Jobs, Unemployment, and Macroeconomic Transmission

Measuring Job Openings: Evidence from Swedish Plant Level Data. In modern macroeconomic models “job openings'' are a key component. Thus, when taking these models to the data we need an empirical counterpart to the theoretical concept of job openings. To achieve this, the literature relies on job vacancies measured either in survey or register data. Insofar as this concept captures the concept of job openings well we should see a tight relationship between vacancies and subsequent hires on the micro level. To investigate this, I analyze a new data set of Swedish hires and job vacancies on the plant level covering the period 2001-2012. I find that vacancies contain little power in predicting hires over and above (i) whether the number of vacancies is positive and (ii) plant size. Building on this, I propose an alternative measure of job openings in the economy. This measure (i) better predicts hiring at the plant level and (ii) provides a better fitting aggregate matching function vis-à-vis the traditional vacancy measure. Firm Level Evidence from Two Vacancy Measures. Using firm level survey and register data for both Sweden and Denmark we show systematic mis-measurement in both vacancy measures. While the register-based measure on the aggregate constitutes a quarter of the survey-based measure, the latter is not a super-set of the former. To obtain the full set of unique vacancies in these two databases, the number of survey vacancies should be multiplied by approximately 1.2. Importantly, this adjustment factor varies over time and across firm characteristics. Our findings have implications for both the search-matching literature and policy analysis based on vacancy measures: observed changes in vacancies can be an outcome of changes in mis-measurement, and are not necessarily changes in the actual number of vacancies. Swedish Unemployment Dynamics. We study the contribution of different labor market flows to business cycle variations in unemployment in the context of a dual labor market. To this end, we develop a decomposition method that allows for a distinction between permanent and temporary employment. We also allow for slow convergence to steady state which is characteristic of European labor markets. We apply the method to a new Swedish data set covering the period 1987-2012 and show that the relative contributions of inflows and outflows to/from unemployment are roughly 60/30. The remaining 10\% are due to flows not involving unemployment. Even though temporary contracts only cover 9-11\% of the working age population, variations in flows involving temporary contracts account for 44\% of the variation in unemployment. We also show that the importance of flows involving temporary contracts is likely to be understated if one does not account for non-steady state dynamics. The New Keynesian Transmission Mechanism: A Heterogeneous-Agent Perspective. We argue that a 2-agent version of the standard New Keynesian model---where a ``worker'' receives only labor income and a “capitalist'' only profit income---offers insights about how income inequality affects the monetary transmission mechanism. Under rigid prices, monetary policy affects the distribution of consumption, but it has no effect on output as workers choose not to change their hours worked in response to wage movements. In the corresponding representative-agent model, in contrast, hours do rise after a monetary policy loosening due to a wealth effect on labor supply: profits fall, thus reducing the representative worker's income. If wages are rigid too, however, the monetary transmission mechanism is active and resembles that in the corresponding representative-agent model. Here, workers are not on their labor supply curve and hence respond passively to demand, and profits are procyclical.

Spatial correlations between the vacuolation, prion protein deposition and surviving neurons in variant Creutzfeldt-Jakob Disease (vCJD)

The histological features of cases of variant Creutzfeldt-Jakob disease (vCJD) are often distributed in the brain in clusters. This study investigated the spatial associations between the clusters of the vacuoles, surviving neurons, and prion protein (PrP) deposits in various brain areas in 11 cases of vCJD. Clusters of vacuoles and surviving neurons were positively correlated in the cerebral cortex but negatively correlated in the dentate gyrus. Clusters of the florid and diffuse type of PrP deposit were not positively correlated with those of either the vacuoles or the surviving neurons although a negative correlation was observed between the florid plaques and surviving neurons in some cortical areas. Clusters of the florid and diffuse deposits were either negatively correlated or uncorrelated. These data suggest: 1) that clusters of vacuoles in the cerebral cortex are associated with the presence of surviving neuronal cell bodies, 2) that the clusters of vacuoles are not spatially related to those of the PrP deposits, and 3) different factors are involved in the pathogenesis of the florid and diffuse PrP deposits.

Spatial correlations between the neuronal inclusions, swollen achromatic neurons, and glial cells in neuronal intermediate filament inclusion disease (NIFID)

Neuronal intermediate filament (IF) inclusion disease (NIFID) is characterized by neuronal loss, neuronal cytoplasmic IF-positive inclusions (NI), swollen neurons (SN), and a glial cell reaction. We studied the spatial correlations between the clusters of NI, SN, and glial cells in four gyri of the temporal lobe (superior temporal gyrus, inferior temporal gyrus, lateral occipitotemporal gyrus, and parahippocampal gyrus) in four cases of NIFID. The densities of histological features (per 50x250 μ sample field) were as follows: NI (mean = 0.41, range 0.28-0.68), SN (mean = 1.41, range 0.47-2.65), glial cell nuclei (mean = 5.21, range 3.63-8.17). The NI and the SN were positively correlated in half of the brain regions examined, the correlations being present at the smallest field size (50x250 μm). The NI were also positively or negatively correlated with the glial cell nuclei in different areas, the negative correlations being present at the smallest field size. Glial cell nuclei were positively or negatively correlated with the SN in different brain areas, mainly at the larger field sizes (400x250 and 800x250 μm). The spatial correlation between the clusters of NI and SN in the cortex suggests their development within the same columns of cells. At first, the glial cell reaction is also confined to these columns but later becomes more generally distributed across the cortex. © Springer-Verlag 2004.

Ultra high-speed transmission using dispersion managed solitons

This thesis presents the results of numerical modelling of ultra high-speed transmission using DM solitons. The theory of propagation in optical fibres is presented with specific reference to optical communication systems. This theory is then expanded to. incorporate dispersion-managed transmission and the dispersion managed soliton. The first part of this work focuses on ultra high-speed dispersion managed soliton propagation in short period dispersion maps. Initially, the cbaracteristics .of dispersion managed soliton propagation in short period dispersion maps are contrasted to those of the more conventional dispersion managed regime. These properties are then utilised to investigate transmission at single channel data rates of 80 Gbit/s, 160 Gbit/s and 320 Gbit/s. For all three data rates, the tolerable limits for transmission over 1000 km, 3000 km and·transoceanic distances are defined. A major limitation of these higher bjt rate systems arises from the problem of noise-induced interactions, which is where the.accumulation of timing jitter causes neighbouring dispersion-managed solitons to interact. In addition, the systems become more sensitive to initial conditions as the data rate increases, .. The second part of the work focuses on contrasting the performance of a range of propagation regimes, from quasi-linear through to soliton-like propagation at 40 Gbit/s for both single channel and WDM dispersion managed transmission. The results indicated that whilst the optimal single channel performance was achieved for soliton-like propagation, the optimal WDM performance was achieved for propagation regime that lay between quasi-linear and soliton-like.

Numerical modelling of devices and advanced transmission schemes embracing Raman effect

This thesis presents a theoretical investigation on applications of Raman effect in optical fibre communication as well as the design and optimisation of various Raman based devices and transmission schemes. The techniques used are mainly based on numerical modelling. The results presented in this thesis are divided into three main parts. First, novel designs of Raman fibre lasers (RFLs) based on Phosphosilicate core fibre are analysed and optimised for efficiency by using a discrete power balance model. The designs include a two stage RFL based on Phosphosilicate core fibre for telecommunication applications, a composite RFL for the 1.6 μm spectral window, and a multiple output wavelength RFL aimed to be used as a compact pump source for fiat gain Raman amplifiers. The use of Phosphosilicate core fibre is proven to effectively reduce the design complexity and hence leads to a better efficiency, stability and potentially lower cost. Second, the generalised Raman amplified gain model approach based on the power balance analysis and direct numerical simulation is developed. The approach can be used to effectively simulate optical transmission systems with distributed Raman amplification. Last, the potential employment of a hybrid amplification scheme, which is a combination between a distributed Raman amplifier and Erbium doped amplifier, is investigated by using the generalised Raman amplified gain model. The analysis focuses on the use of the scheme to upgrade a standard fibre network to 40 Gb/s system.

Numerically optimized implementations, mitigation and simulations of polarisation mode dispersion in real-time transmission systems

The aim of this thesis is to present numerical investigations of the polarisation mode dispersion (PMD) effect. Outstanding issues on the side of the numerical implementations of PMD are resolved and the proposed methods are further optimized for computational efficiency and physical accuracy. Methods for the mitigation of the PMD effect are taken into account and simulations of transmission system with added PMD are presented. The basic outline of the work focusing on PMD can be divided as follows. At first the widely-used coarse-step method for simulating the PMD phenomenon as well as a method derived from the Manakov-PMD equation are implemented and investigated separately through the distribution of a state of polarisation on the Poincaré sphere, and the evolution of the dispersion of a signal. Next these two methods are statistically examined and compared to well-known analytical models of the probability distribution function (PDF) and the autocorrelation function (ACF) of the PMD phenomenon. Important optimisations are achieved, for each of the aforementioned implementations in the computational level. In addition the ACF of the coarse-step method is considered separately, based on the result which indicates that the numerically produced ACF, exaggerates the value of the correlation between different frequencies. Moreover the mitigation of the PMD phenomenon is considered, in the form of numerically implementing Low-PMD spun fibres. Finally, all the above are combined in simulations that demonstrate the impact of the PMD on the quality factor (Q=factor) of different transmission systems. For this a numerical solver based on the coupled nonlinear Schrödinger equation is created which is otherwise tested against the most important transmission impairments in the early chapters of this thesis.

Transmission of data under multipath transmission conditions

The explosive growth in microprocessor technology and the increasing use of computers to store information has increased the demand for data communication channels. Because of this, data communication to mobile vehicles is increasing rapidly. In addition, data communication is seen as a method of relieving the current congestion of mobile radio telephone bands in the U.K. Highly reliable data communication over mobile radio channels is particularly difficult to achieve, primarily due to fading caused by multipath interference. In this thesis a data communication system is described for use over radio channels impaired by multipath interference. The thesis first describes radio communication in general, and multipath interference In particular. The practical aspects of fading channels are stressed because of their importance in the development of the system. The current U.K. land mobile radio scene is then reviewed, with particular emphasis on the use of existing mobile radio equipment for data communication purposes. The development of the data communication system is then described. This system is microprocessor based and uses an advanced form of automatic request repeat (ARQ) operation. It can be configured to use either existing radio-telephone equipment, totally new equipment specifically designed for data communication, or any combination of the two. Due to its adaptability, the system can automatically optimise itself for use over any channel, even if the channel parameters are changing rapidly. Results obtained from a particular implementation of the system, which is described in full, are presented. These show how the operation of the system has to change to accomodate changes in the channel. Comparisons are made between the practical results and the theoretical limits of the system.

Soliton propagation through a disordered system:statistics of the transmission delay

We have studied the soliton propagation through a segment containing random pointlike scatterers. In the limit of small concentration of scatterers when the mean distance between the scatterers is larger than the soliton width, a method has been developed for obtaining the statistical characteristics of the soliton transmission through the segment. The method is applicable for any classical particle traversing through a disordered segment with the given velocity transformation after each act of scattering. In the case of weak scattering and relatively short disordered segment the transmission time delay of a fast soliton is mostly determined by the shifts of the soliton center after each act of scattering. For sufficiently long segments the main contribution to the delay is due to the shifts of the amplitude and velocity of a fast soliton after each scatterer. Corresponding crossover lengths for both cases of light and heavy solitons have been obtained. We have also calculated the exact probability density function of the soliton transmission time delay for a sufficiently long segment. In the case of weak identical scatterers the latter is a universal function which depends on a sole parameter—the mean number of scatterers in a segment.