Generation of orange light from a PPKTP waveguide end-pumped by a quantum-dot tuneable laser

Here we present a compact all-room-temperature frequency-doubling scheme generating orange light, using a PPKTP waveguide and a quantum-dot external cavity diode laser (QD-ECDL). The maximum output power for the second harmonic generated light (SHG) was 1.43 mW at 613 nm, achieved for 70 mW of launched pump power at 1226 nm. This represents an important step towards a compact and wall-plug-efficient coherent orange light source, operating at room temperature.

Experiments on the generation of activated carbon from biomass

Activated carbon is generated from various waste biomass sources like rice straw, wheat straw, wheat straw pellets, olive stones, pistachios shells, walnut shells, beech wood and hardcoal. After drying the biomass is pyrolysed in the temperature range of 500-600 °C at low heating rates of 10 K/min. The activation of the chars is performed as steam activation at temperatures between 800 °C and 900 °C. Both the pyrolysis and activation experiments were run in lab-scale facilities. It is shown that nut shells provide high active surfaces of 1000-1300 m/g whereas the active surface of straw matters does hardly exceed 800 m/g which might be a result of the high ash content of the straws and the slightly higher carbon content of the nut shells. The active surface is detected by BET method. Besides the testing of a many types of biomass for the suitability as base material in the activated carbon production process, the experiments allow for the determination of production parameters like heating rate and pyrolysis temperature, activation time and temperature as well as steam flux which are necessary for the scale up of the process chain. © 2006 Elsevier B.V. All rights reserved.

The challenges of representing human behaviour in simulation models:some case examples from supply chain, evacuation modelling and rail disruption

As more of the economy moves from traditional manufacturing to the service sector, the nature of work is becoming less tangible and thus, the representation of human behaviour in models is becoming more important. Representing human behaviour and decision making in models is challenging, both in terms of capturing the essence of the processes, and also the way that those behaviours and decisions are or can be represented in the models themselves. In order to advance understanding in this area, a useful first step is to evaluate and start to classify the various types of behaviour and decision making that are required to be modelled. This talk will attempt to set out and provide an initial classification of the different types of behaviour and decision making that a modeller might want to represent in a model. Then, it will be useful to start to assess the main methods of simulation in terms of their capability in representing these various aspects. The three main simulation methods, System Dynamics, Agent Based Modelling and Discrete Event Simulation all achieve this to varying degrees. There is some evidence that all three methods can, within limits, represent the key aspects of the system being modelled. The three simulation approaches are then assessed for their suitability in modelling these various aspects. Illustration of behavioural modelling will be provided from cases in supply chain management, evacuation modelling and rail disruption.

Generation of 49-fs pulses directly from distributed Kerr-lens mode-locked Yb:YAG thin-disk oscillator

The concept of distributed Kerr-lens mode-locking and a thin-disk Yb:YAG oscillator based on this concept are presented. The described oscillator directly generates pulses with a duration of 49 fs and spectral width of 33 nm

Social acceptance of renewable energy: Some examples from Europe and Developing Africa

Current energy systems are in most instances not fully working sustainably. The provision and use of energy only consider limited resources, risk potential or financial constraints on a limited scale. Furthermore, the knowledge and benefits are only available for a minor group of the population or are outright neglected. The availability of different resources for energy purposes determines economic development, as well as the status of the society and the environment. The access to energy grids has an impact on socio-economic living standards of communities. This not fully developed system is causing climate change with all its related outcomes. This investigation takes into consideration different views on renewable energy systems — such as international discussions about biomass use for energy production, “fuel versus food”, biogas use — and attempts to compare major prospects of social acceptance of renewable energy in Europe and Africa. Can all obstacles to the use of renewable energy be so profound that the overall strategy of reducing anthropogenic causes of climate change be seriously affected?

Social acceptance of renewable energy: Some examples from Europe and Developing Africa

Current energy systems are in most instances not fully working sustainably. The provision and use of energy only consider limited resources, risk potential or financial constraints on a limited scale. Furthermore, the knowledge and benefits are only available for a minor group of the population or are outright neglected. The availability of different resources for energy purposes determines economic development, as well as the status of the society and the environment. The access to energy grids has an impact on socio-economic living standards of communities. This not fully developed system is causing climate change with all its related outcomes. This investigation takes into consideration different views on renewable energy systems — such as international discussions about biomass use for energy production, “fuel versus food”, biogas use — and attempts to compare major prospects of social acceptance of renewable energy in Europe and Africa. Can all obstacles to the use of renewable energy be so profound that the overall strategy of reducing anthropogenic causes of climate change be seriously affected?

Open innovation in the performing arts. Examples from contemporary dance and theatre production

Scholarship on open innovation examines the different shades of opening up the innovation process of firms, where the most important feature is sourcing in knowledge. In this paper I examine the implications of adapting open innovation frames to a field where it was not investigated before: performing arts (contemporary dance and theatre). I draw on case studies and demonstrate that open innovation strategies are viable for artistic production. Independent companies purposefully mining out external knowledge in production, and commercializing on the spillovers of their body of knowledge, put themselves on the shelf of firms adopting and adapting to open innovation.

Carbon and nutrient storage in subtropical seagrass meadows: examples from Florida Bay and Shark Bay

Seagrass meadows in Florida Bay and Shark Bay, contain substantial stores of both organic carbon and nutrients. Soils from both systems are predominantly calcium carbonate, with an average of 82.1% CaCO3 in Florida Bay compared to 71.3% in Shark Bay. Soils from Shark Bay had, on average, 21% higher organic carbon content and 35% higher phosphorus content than Florida Bay. Further, soils from Shark Bay had lower mean dry bulk density (0.78 ± 0.01 g mL-1) than those from Florida Bay (0.84 ± 0.02 mg mL-1). The most hypersaline regions of both bays had higher organic carbon content in surficial soils. Profiles of organic carbon and phosphorus from Florida Bay indicate that this system has experienced an increase in P delivery and primary productivity over the last century; in contrast, decreasing organic carbon and phosphorus with depth in the soil profiles in Shark Bay point to a decrease in phosphorus delivery and primary productivity over the last 1000 y. The total ecosystem stocks of stored organic C in Florida Bay averages 163.5 MgCorg ha-1, lower than the average of 243.0 MgCorg ha-1 for Shark Bay; but these values place Shark and Florida Bays among the global hotspots for organic C storage in coastal ecosystems.

Melt inclusions from volcan de Colima, Mexico: complex examples of magmatic differentiation

Melt inclusions are minute magma bodies trapped within growing crystals. Their chemical compositions are useful in deciphering pre-eruptive conditions and magma evolution. The present study examined melt inclusions trapped in phenocrysts from the 3rd and 4th magmatic cycles (1869-1988) at Volcan de Colima, Mexico. Melt inclusions have highly evolved chemical compositions: 65-77% SiO2, >12% A12O3, 3-6% Na2O and K20 and less than 5.5% Fe and Mg. Major element compositions suggest that they are strongly differentiated magmas controlled by fractionation of plagioclase, opx, cpx and hornblende. Water concentrations were measured to be 2.7-3.5 wt. % in cpx hosted inclusions and 0.3-0.7 wt % in opx and plagioclase. Trace element compositions are anomalously low and inversely correlate with water. From this we deduce that Colima lavas and scorias simultaneously differentiate and degas. Moreover, hornblende rim growth rates constrain the ascent of the Colima magmas to -100 days for passive eruptions and >4 days for plinian eruptions.

Medium change monitoring using ambient seismic noise and coda wave interferometry: examples from intraplate NE Brazil and the Mid-Atlantic Ridge

This thesis presents and discusses the results of ambient seismic noise correlation for two different environments: intraplate and Mid-Atlantic Ridge. The coda wave interferometry method has also been tested for the intraplate data. Ambient noise correlation is a method that allows to retrieve the structural response between two receivers from ambient noise records, as if one of the station was a virtual source. It has been largely used in seismology to image the subsurface and to monitor structural changes associated mostly with volcanic eruptions and large earthquakes. In the intraplate study, we were able to detect localized structural changes related to a small earthquake swarm, which main event is mR 3.7, North-East of Brazil. We also showed that the 1-bit normalization and spectral whitening result on the loss of waveform details and that the phase auto-correlation, which is amplitude unbiased, seems to be more sensitive and robust for our analysis of a small earthquake swarm. The analysis of 6 months of data using cross-correlations detect clear medium changes soon after the main event while the auto-correlations detect changes essentially after 1 month. It could be explained by fluid pressure redistribution which can be initiated by hydromechanical changes and opened path ways to shallower depth levels due to later occurring earthquakes. In the Mid-Atlantic Ridge study, we investigate structural changes associated with a mb 4.9 earthquake in the region of the Saint Paul transform fault. The data have been recorded by a single broadband seismic station located at less than 200 km from the Mid-Atlantic ridge. The results of the phase auto-correlation for a 5-month period, show a strong co-seismic medium change followed by a relatively fast post-seismic recovery. This medium change is likely related to the damages caused by the earthquake’s ground shaking. The healing process (filling of the new cracks) that lasted 60 days can be decomposed in two phases, a fast recovery (70% in ~30 days) in the early post-seismic stage and a relatively slow recovery later (30% in ~30 days). In the coda wave interferometry study, we monitor temporal changes of the subsurface caused by the small intraplate earthquake swarm mentioned previously. The method was first validated with synthetics data. We were able to detect a change of 2.5% in the source position and a 15% decrease of the scatterers’ amount. Then, from the real data, we observed a rapid decorrelation of the seismic coda after the mR 3.7 seismic event. This indicates a rapid change of the subsurface in the fault’s region induced by the earthquake.

Medium change monitoring using ambient seismic noise and coda wave interferometry: examples from intraplate NE Brazil and the Mid-Atlantic Ridge

This thesis presents and discusses the results of ambient seismic noise correlation for two different environments: intraplate and Mid-Atlantic Ridge. The coda wave interferometry method has also been tested for the intraplate data. Ambient noise correlation is a method that allows to retrieve the structural response between two receivers from ambient noise records, as if one of the station was a virtual source. It has been largely used in seismology to image the subsurface and to monitor structural changes associated mostly with volcanic eruptions and large earthquakes. In the intraplate study, we were able to detect localized structural changes related to a small earthquake swarm, which main event is mR 3.7, North-East of Brazil. We also showed that the 1-bit normalization and spectral whitening result on the loss of waveform details and that the phase auto-correlation, which is amplitude unbiased, seems to be more sensitive and robust for our analysis of a small earthquake swarm. The analysis of 6 months of data using cross-correlations detect clear medium changes soon after the main event while the auto-correlations detect changes essentially after 1 month. It could be explained by fluid pressure redistribution which can be initiated by hydromechanical changes and opened path ways to shallower depth levels due to later occurring earthquakes. In the Mid-Atlantic Ridge study, we investigate structural changes associated with a mb 4.9 earthquake in the region of the Saint Paul transform fault. The data have been recorded by a single broadband seismic station located at less than 200 km from the Mid-Atlantic ridge. The results of the phase auto-correlation for a 5-month period, show a strong co-seismic medium change followed by a relatively fast post-seismic recovery. This medium change is likely related to the damages caused by the earthquake’s ground shaking. The healing process (filling of the new cracks) that lasted 60 days can be decomposed in two phases, a fast recovery (70% in ~30 days) in the early post-seismic stage and a relatively slow recovery later (30% in ~30 days). In the coda wave interferometry study, we monitor temporal changes of the subsurface caused by the small intraplate earthquake swarm mentioned previously. The method was first validated with synthetics data. We were able to detect a change of 2.5% in the source position and a 15% decrease of the scatterers’ amount. Then, from the real data, we observed a rapid decorrelation of the seismic coda after the mR 3.7 seismic event. This indicates a rapid change of the subsurface in the fault’s region induced by the earthquake.

Next generation e-learning platform: virtual laboratory simulations

Bioscience subjects require a significant amount of training in laboratory techniques to produce highly skilled science graduates. Many techniques which are currently used in diagnostic, research and industrial laboratories require expensive equipment for single users; examples of which include next generation sequencing, quantitative PCR, mass spectrometry and other analytical techniques. The cost of the machines, reagents and limited access frequently preclude undergraduate students from using such cutting edge techniques. In addition to cost and availability, the time taken for analytical runs on equipment such as High Performance Liquid Chromatography (HPLC) does not necessarily fit with the limitations of timetabling. Understanding the theory underlying these techniques without the accompanying practical classes can be unexciting for students. One alternative from wet laboratory provision is to use virtual simulations of such practical which enable students to see the machines and interact with them to generate data. The Faculty of Science and Technology at the University of Westminster has provided all second and third year undergraduate students with iPads so that these students all have access to a mobile device to assist with learning. We have purchased licences from Labster to access a range of virtual laboratory simulations. These virtual laboratories are fully equipped and require student responses to multiple answer questions in order to progress through the experiment. In a pilot study to look at the feasibility of the Labster virtual laboratory simulations with the iPad devices; second year Biological Science students (n=36) worked through the Labster HPLC simulation on iPads. The virtual HPLC simulation enabled students to optimise the conditions for the separation of drugs. Answers to Multiple choice questions were necessary to progress through the simulation, these focussed on the underlying principles of the HPLC technique. Following the virtual laboratory simulation students went to a real HPLC in the analytical suite in order to separate of asprin, caffeine and paracetamol. In a survey 100% of students (n=36) in this cohort agreed that the Labster virtual simulation had helped them to understand HPLC. In free text responses one student commented that "The terminology is very clear and I enjoyed using Labster very much”. One member of staff commented that “there was a very good knowledge interaction with the virtual practical”.

Broad balmer wings in BA Hyper/Supergiants distorted by diffuse interstellar bands: five examples in the 30 Doradus Region from the VLT-Flames Tarantula Survey

Extremely broad emission wings at Hβ and Hα have been found in VLT-FLAMES Tarantula Survey data for five very luminous BA supergiants in or near 30 Doradus in the Large Magellanic Cloud. The profiles of both lines are extremely asymmetrical, which we have found to be caused by very broad diffuse interstellar bands (DIBs) in the longward wing of Hβ and the shortward wing of Hα. These DIBs are well known to interstellar but not to many stellar specialists, so that the asymmetries may be mistaken for intrinsic features. The broad emission wings are generally ascribed to electron scattering, although we note difficulties for that interpretation in some objects. Such profiles are known in some Galactic hyper/supergiants and are also seen in both active and quiescent Luminous Blue Variables (LBVs). No prior or current LBV activity is known in these 30 Dor stars, although a generic relationship to LBVs is not excluded; subject to further observational and theoretical investigation, it is possible that these very luminous supergiants are approaching the LBV stage for the first time. Their locations in the HRD and presumed evolutionary tracks are consistent with that possibility. The available evidence for spectroscopic variations of these objects is reviewed, while recent photometric monitoring does not reveal variability. A search for circumstellar nebulae has been conducted, with an indeterminate result for one of them.