Reducing residual amplitude modulation in electro-optic phase modulators by erasing photorefractive scatter

Residual amplitude modulation (RAM) is an unwanted noise source in electro-optic phase modulators. The analysis presented shows that while the magnitude of the RAM produced by a MgO:LiNbO3 modulator increases with intensity, its associated phase becomes less well defined. This combination results in temporal fluctuations in RAM that increase with intensity. This behaviour is explained by the presented phenomenological model based on gradually evolving photorefractive scattering centres randomly distributed throughout the optically thick medium. This understanding is exploited to show that RAM can be reduced to below the 10-5 level by introducing an intense optical beam to erase the photorefractive scatter.

Unnatural selection : curricular conversations in TIP 1962–2012

Our task is to consider the evolving perspectives around curriculum documented in the Theory Into Practice (TIP) corpus to date. The 50 years in question, 1962–2012, account for approximately half the history of mass institutionalized schooling. Over this time, the upper age of compulsory schooling has crept up, stretching the school curriculum's reach, purpose, and clientele. These years also span remarkable changes in the social fabric, challenging deep senses of the nature and shelf-life of knowledge, whose knowledge counts, what science can and cannot deliver, and the very purpose of education. The school curriculum is a key social site where these challenges have to be addressed in a very practical sense, through a design on the future implemented within the resources and politics of the present. The task's metaphor of ‘evolution’ may invoke a sense of gradual cumulative improvement, but equally connotes mutation, hybridization, extinction, survival of the fittest, and environmental pressures. Viewed in this way, curriculum theory and practice cannot be isolated and studied in laboratory conditions—there is nothing natural, neutral, or self-evident about what knowledge gets selected into the curriculum. Rather, the process of selection unfolds as a series of messy, politically contaminated, lived experiments; thus curriculum studies require field work in dynamic open systems. We subscribe to Raymond Williams' approach to social change, which he argues is not absolute and abrupt, one set of ideas neatly replacing the other. For Williams, newly emergent ideas have to compete against the dominant mindset and residual ideas “still active in the cultural process'” (Williams, 1977, p. 122). This means ongoing debates. For these reasons, we join Schubert (1992) in advocating “continuous reconceptualising of the flow of experience” (p. 238) by both researchers and practitioners.

Modeling the cumulative genetic risk for multiple sclerosis from genome-wide association data

Background: Multiple sclerosis (MS) is the most common cause of chronic neurologic disability beginning in early to middle adult life. Results from recent genome-wide association studies (GWAS) have substantially lengthened the list of disease loci and provide convincing evidence supporting a multifactorial and polygenic model of inheritance. Nevertheless, the knowledge of MS genetics remains incomplete, with many risk alleles still to be revealed. Methods: We used a discovery GWAS dataset (8,844 samples, 2,124 cases and 6,720 controls) and a multi-step logistic regression protocol to identify novel genetic associations. The emerging genetic profile included 350 independent markers and was used to calculate and estimate the cumulative genetic risk in an independent validation dataset (3,606 samples). Analysis of covariance (ANCOVA) was implemented to compare clinical characteristics of individuals with various degrees of genetic risk. Gene ontology and pathway enrichment analysis was done using the DAVID functional annotation tool, the GO Tree Machine, and the Pathway-Express profiling tool. Results: In the discovery dataset, the median cumulative genetic risk (P-Hat) was 0.903 and 0.007 in the case and control groups, respectively, together with 79.9% classification sensitivity and 95.8% specificity. The identified profile shows a significant enrichment of genes involved in the immune response, cell adhesion, cell communication/ signaling, nervous system development, and neuronal signaling, including ionotropic glutamate receptors, which have been implicated in the pathological mechanism driving neurodegeneration. In the validation dataset, the median cumulative genetic risk was 0.59 and 0.32 in the case and control groups, respectively, with classification sensitivity 62.3% and specificity 75.9%. No differences in disease progression or T2-lesion volumes were observed among four levels of predicted genetic risk groups (high, medium, low, misclassified). On the other hand, a significant difference (F = 2.75, P = 0.04) was detected for age of disease onset between the affected misclassified as controls (mean = 36 years) and the other three groups (high, 33.5 years; medium, 33.4 years; low, 33.1 years). Conclusions: The results are consistent with the polygenic model of inheritance. The cumulative genetic risk established using currently available genome-wide association data provides important insights into disease heterogeneity and completeness of current knowledge in MS genetics.

Dependence of residual amplitude noise in electro-optic phase modulators on the intensity distribution of the incident field

Our results demonstrate that photorefractive residual amplitude modulation (RAM) noise in electro-optic modulators (EOMs) can be reduced by modifying the incident beam intensity distribution. Here we report an order of magnitude reduction in RAM when beams with uniform intensity (flat-top) profiles, generated with an LCOS-SLM, are used instead of the usual fundamental Gaussian mode (TEM00). RAM arises from the photorefractive amplified scatter noise off the defects and impurities within the crystal. A reduction in RAM is observed with increasing intensity uniformity (flatness), which is attributed to a reduction in space charge field on the beam axis. The level of RAM reduction that can be achieved is physically limited by clipping at EOM apertures, with the observed results agreeing well with a simple model. These results are particularly important in applications where the reduction of residual amplitude modulation to 10^-6 is essential.

Real - time prediction of rainfall induced instability of residual soil slopes associated with deep cracks

The early warning based on real-time prediction of rain-induced instability of natural residual slopes helps to minimise human casualties due to such slope failures. Slope instability prediction is complicated, as it is influenced by many factors, including soil properties, soil behaviour, slope geometry, and the location and size of deep cracks in the slope. These deep cracks can facilitate rainwater infiltration into the deep soil layers and reduce the unsaturated shear strength of residual soil. Subsequently, it can form a slip surface, triggering a landslide even in partially saturated soil slopes. Although past research has shown the effects of surface-cracks on soil stability, research examining the influence of deep-cracks on soil stability is very limited. This study aimed to develop methodologies for predicting the real-time rain-induced instability of natural residual soil slopes with deep cracks. The results can be used to warn against potential rain-induced slope failures. The literature review conducted on rain induced slope instability of unsaturated residual soil associated with soil crack, reveals that only limited studies have been done in the following areas related to this topic: - Methods for detecting deep cracks in residual soil slopes. - Practical application of unsaturated soil theory in slope stability analysis. - Mechanistic methods for real-time prediction of rain induced residual soil slope instability in critical slopes with deep cracks. Two natural residual soil slopes at Jombok Village, Ngantang City, Indonesia, which are located near a residential area, were investigated to obtain the parameters required for the stability analysis of the slope. A survey first identified all related field geometrical information including slope, roads, rivers, buildings, and boundaries of the slope. Second, the electrical resistivity tomography (ERT) method was used on the slope to identify the location and geometrical characteristics of deep cracks. The two ERT array models employed in this research are: Dipole-dipole and Azimuthal. Next, bore-hole tests were conducted at different locations in the slope to identify soil layers and to collect undisturbed soil samples for laboratory measurement of the soil parameters required for the stability analysis. At the same bore hole locations, Standard Penetration Test (SPT) was undertaken. Undisturbed soil samples taken from the bore-holes were tested in a laboratory to determine the variation of the following soil properties with the depth: - Classification and physical properties such as grain size distribution, atterberg limits, water content, dry density and specific gravity. - Saturated and unsaturated shear strength properties using direct shear apparatus. - Soil water characteristic curves (SWCC) using filter paper method. - Saturated hydraulic conductivity. The following three methods were used to detect and simulate the location and orientation of cracks in the investigated slope: (1) The electrical resistivity distribution of sub-soil obtained from ERT. (2) The profile of classification and physical properties of the soil, based on laboratory testing of soil samples collected from bore-holes and visual observations of the cracks on the slope surface. (3) The results of stress distribution obtained from 2D dynamic analysis of the slope using QUAKE/W software, together with the laboratory measured soil parameters and earthquake records of the area. It was assumed that the deep crack in the slope under investigation was generated by earthquakes. A good agreement was obtained when comparing the location and the orientation of the cracks detected by Method-1 and Method-2. However, the simulated cracks in Method-3 were not in good agreement with the output of Method-1 and Method-2. This may have been due to the material properties used and the assumptions made, for the analysis. From Method-1 and Method-2, it can be concluded that the ERT method can be used to detect the location and orientation of a crack in a soil slope, when the ERT is conducted in very dry or very wet soil conditions. In this study, the cracks detected by the ERT were used for stability analysis of the slope. The stability of the slope was determined using the factor of safety (FOS) of a critical slip surface obtained by SLOPE/W using the limit equilibrium method. Pore-water pressure values for the stability analysis were obtained by coupling the transient seepage analysis of the slope using finite element based software, called SEEP/W. A parametric study conducted on the stability of an investigated slope revealed that the existence of deep cracks and their location in the soil slope are critical for its stability. The following two steps are proposed to predict the rain-induced instability of a residual soil slope with cracks. (a) Step-1: The transient stability analysis of the slope is conducted from the date of the investigation (initial conditions are based on the investigation) to the preferred date (current date), using measured rainfall data. Then, the stability analyses are continued for the next 12 months using the predicted annual rainfall that will be based on the previous five years rainfall data for the area. (b) Step-2: The stability of the slope is calculated in real-time using real-time measured rainfall. In this calculation, rainfall is predicted for the next hour or 24 hours and the stability of the slope is calculated one hour or 24 hours in advance using real time rainfall data. If Step-1 analysis shows critical stability for the forthcoming year, it is recommended that Step-2 be used for more accurate warning against the future failure of the slope. In this research, the results of the application of the Step-1 on an investigated slope (Slope-1) showed that its stability was not approaching a critical value for year 2012 (until 31st December 2012) and therefore, the application of Step-2 was not necessary for the year 2012. A case study (Slope-2) was used to verify the applicability of the complete proposed predictive method. A landslide event at Slope-2 occurred on 31st October 2010. The transient seepage and stability analyses of the slope using data obtained from field tests such as Bore-hole, SPT, ERT and Laboratory tests, were conducted on 12th June 2010 following the Step-1 and found that the slope in critical condition on that current date. It was then showing that the application of the Step-2 could have predicted this failure by giving sufficient warning time.

Galvanic replacement mediated synthesis of hollow Pt nanocatalysts : significance of residual Ag for the H2 evolution reaction

With the increasing popularity of the galvanic replacement approach towards the development of bimetallic nanocatalysts, special emphasis has been focused on minimizing the use of expensive metal (e.g. Pt), in the finally formed nanomaterials (e.g. Ag/Pt system as a possible catalyst for fuel cells). However, the complete removal of the less active sacrificial template is generally not achieved during galvanic replacement, and its residual presence may significantly impact on the electrocatalytic properties of the final material. Here, we investigate the hydrogen evolution reaction (HER) activity of Ag nanocubes replaced with different amounts of Pt, and demonstrate how the bimetallic composition significantly affects the activity of the alloyed nanomaterial.

Cumulative and comparative social media analytics for crisis communication

This paper draws on comparative analyses of Twitter data sets – over time and across different kinds of natural disasters and different national contexts – to demonstrate the value of shared, cumulative approaches to social media analytics in the context of crisis communication.

A neutron diffraction investigation of residual stresses in rail ends after severe deformation of rail surfaces

Insulated rail joints (IRJs) are a primary component of the rail track safety and signalling systems. Rails are supported by two fishplates which are fastened by bolts and nuts and, with the support of sleepers and track ballast, form an integrated assembly. IRJ failure can result from progressive defects, the propagation of which is influenced by residual stresses in the rail. Residual stresses change significantly during service due to the complex deformation and damage effects associated with wheel rolling, sliding and impact. IRJ failures can occur when metal flows over the insulated rail gap (typically 6-8 mm width), breaks the electrically isolated section of track and results in malfunction of the track signalling system. In this investigation, residual stress measurements were obtained from rail-ends which had undergone controlled amounts of surface plastic deformation using a full scale wheel-on-track simulation test rig. Results were compared with those obtained from similar investigations performed on rail ends associated with ex-service IRJs. Residual stresses were measured by neutron diffraction at the Australian Nuclear Science and Technology Organisation (ANSTO). Measurements with constant gauge volume 3x3x3 mm3 were carried in the central vertical plane on 5mm thick sliced rail samples cut by an electric discharge machine (EDM). Stress evolution at the rail ends was found to exhibit characteristics similar to those of the ex-service rails, with a compressive zone of 5mm deep that is counterbalanced by a tension zone beneath, extending to a depth of around 15mm. However, in contrast to the ex-service rails, the type of stress distribution in the test-rig deformed samples was apparently different due to the localization of load under the particular test conditions. In the latter, in contrast with clear stress evolution, there was no obvious evolution of d0. Since d0 reflects rather long-term accumulation of crystal lattice damage and microstructural changes due to service load, the loading history of the test rig samples has not reached the same level as the ex-service rails. It is concluded that the wheel-on-rail simulation rig provides the potential capability for testing the wheel-rail rolling contact conditions in rails, rail ends and insulated rail joints.

Residual stresses in rail-ends from the in-service insulated rail joints using neutron diffraction

Insulated rail joints (IRJs) are an integral part of the rail track signaling system and pose significant maintenance and replacement costs due to their low and fluctuating service lives. Failure occurs mainly in rail head region, bolt- holes of fishplates and web-holes of the rails. Propagation of cracks is influenced by the evolution of internal residual stresses in rails during rail manufacturing (hot-rolling, roller-straightening, and head-hardening process), and during service, particularly in heavy rail haul freight systems where loads are high. In this investigation, rail head accumulated residual stresses were analysed using neutron diffraction at the Australian Nuclear Science and Technology Organisation (ANSTO). Two ex-service two head-hardened rail joints damaged under different loading were examined and results were compared with those obtained from an unused rail joint reference sample in order to differentiate the stresses developed during rail manufacturing and stresses accumulated during rail service. Neutron diffraction analyses were carried out on the samples in longitudinal, transverse and vertical directions, and on 5mm thick sliceed samples cut by Electric Discharge Machining (EDM). For the rail joints from the service line, irrespective of loading conditions and in-service times, results revealed similar depth profiles of stress distribution. Evolution of residual stress fields in rails due to service was also accompanied by evidence of larger material flow based on reflected light and scanning electron microscopy studies. Stress evolution in the vicinity of rail ends was characterised by a compressive layer, approximately 5 mm deep, and a tension zone located approximately 5- 15mm below the surfaces. A significant variation of d0 with depth near the top surface was detected and was attributed to decarburization in the top layer induced by cold work. Stress distributions observed in longitudinal slices of the two different deformed rail samples were found to be similar. For the undeformed rail, the stress distributions obtained could be attributed to variations associated with thermo-mechanical history of the rail.

A comprehensive analysis of parameter settings for novelty-biased cumulative gain

In the TREC Web Diversity track, novelty-biased cumulative gain (α-NDCG) is one of the official measures to assess retrieval performance of IR systems. The measure is characterised by a parameter, α, the effect of which has not been thoroughly investigated. We find that common settings of α, i.e. α=0.5, may prevent the measure from behaving as desired when evaluating result diversification. This is because it excessively penalises systems that cover many intents while it rewards those that redundantly cover only few intents. This issue is crucial since it highly influences systems at top ranks. We revisit our previously proposed threshold, suggesting α be set on a query-basis. The intuitiveness of the measure is then studied by examining actual rankings from TREC 09-10 Web track submissions. By varying α according to our query-based threshold, the discriminative power of α-NDCG is not harmed and in fact, our approach improves α-NDCG's robustness. Experimental results show that the threshold for α can turn the measure to be more intuitive than using its common settings.

A query-basis approach to parametrizing novelty-biased cumulative gain

Novelty-biased cumulative gain (α-NDCG) has become the de facto measure within the information retrieval (IR) community for evaluating retrieval systems in the context of sub-topic retrieval. Setting the incorrect value of parameter α in α-NDCG prevents the measure from behaving as desired in particular circumstances. In fact, when α is set according to common practice (i.e. α = 0.5), the measure favours systems that promote redundant relevant sub-topics rather than provide novel relevant ones. Recognising this characteristic of the measure is important because it affects the comparison and the ranking of retrieval systems. We propose an approach to overcome this problem by defining a safe threshold for the value of α on a query basis. Moreover, we study its impact on system rankings through a comprehensive simulation.

Cisplatin treatment of primary and metastatic epithelial ovarian carcinomas generates residual cells with mesenchymal stem cell-like profile

Epithelial mesenchymal transition (EMT) and cancer stem cells (CSC) have been associated with resistance to chemotherapy. Eighty percent of ovarian cancer patients initially respond to platinum-based combination therapy but most return with recurrence and ultimate demise. To better understand such chemoresistance we have assessed the potential role of EMT in tumor cells collected from advanced-stage ovarian cancer patients and the ovarian cancer cell line OVCA 433 in response to cisplatin in vitro. We demonstrate that cisplatin-induced transition from epithelial to mesenchymal morphology in residual cancer cells correlated with reduced E-cadherin, and increased N-cadherin and vimentin expression. The mRNA expression of Snail, Slug, Twist, and MMP-2 were significantly enhanced in response to cisplatin and correlated with increased migration. This coincided with increased cell surface expression of CSC-like markers such as CD44, α2 integrin subunit, CD117, CD133, EpCAM, and the expression of stem cell factors Nanog and Oct-4. EMT and CSC-like changes in response to cisplatin correlated with enhanced activation of extracellular signal-regulated kinase (ERK)1/2. The selective MEK inhibitor U0126 inhibited ERK2 activation and partially suppressed cisplatin-induced EMT and CSC markers. In vivo xenotransplantation of cisplatin-treated OVCA 433 cells in zebrafish embryos demonstrated significantly enhanced migration of cells compared to control untreated cells. U0126 inhibited cisplatin-induced migration of cells in vivo, suggesting that ERK2 signaling is critical to cisplatin-induced EMT and CSC phenotypes, and that targeting ERK2 in the presence of cisplatin may reduce the burden of residual tumor, the ultimate cause of recurrence in ovarian cancer patients.

Default judgment - whether irregular - whether court has residual discretion not to set aside default judgment irregularly entered

In CB Richard Ellis (C) Pty Ltd v Wingate Properties Pty Ltd [2005] QDC 399 McGill DCJ examined whether the court now has a discretion to set aside an irregularly entered default judgment.

Generalised cumulative arrays in secret sharing

Cumulative arrays have played an important role in the early development of the secret sharing theory. They have not been subject to extensive study so far, as the secret sharing schemes built on them generally result in much larger sizes of shares, when compared with other conventional approaches. Recent works in threshold cryptography show that cumulative arrays may be the appropriate building blocks in non-homomorphic threshold cryptosystems where the conventional secret sharing methods are generally of no use. In this paper we study several extensions of cumulative arrays and show that some of these extensions significantly improve the performance of conventional cumulative arrays. In particular, we derive bounds on generalised cumulative arrays and show that the constructions based on perfect hash families are asymptotically optimal. We also introduce the concept of ramp perfect hash families as a generalisation of perfect hash families for the study of ramp secret sharing schemes and ramp cumulative arrays.

From short pulses to short breaks : exotic plasma bullets via residual electron control

Plasma plumes with exotically segmented channel structure and plasma bullet propagation are produced in atmospheric plasma jets. This is achieved by tailoring interruptions of a continuous DC power supply over the time scales of lifetimes of residual electrons produced by the preceding discharge phase. These phenomena are explained by studying the plasma dynamics using nanosecond-precision imaging. One of the plumes is produced using 2-10μs interruptions in the 8kV DC voltage and features a still bright channel from which a propagating bullet detaches. A shorter interruption of 900ns produces a plume with the additional long conducting dark channel between the jet nozzle and the bright area. The bullet size, formation dynamics, and propagation speed and distance can be effectively controlled. This may lead to micrometer-and nanosecond-precision delivery of quantized plasma bits, warranted for next-generation health, materials, and device technologies.