bluuebunny/crossref_metadata_2025 huggingface dataset:
Pathological gambling and the treatment of psychosis with
aripiprazole: case reports
Authors: Smith Neil , Kitchenham Nathan , Bowden-Jones Henrietta
Published: July 2011

This paper details three case reports that suggest that pathological
gambling activity may have been adversely modified following treatment for
psychosis with the antipsychotic aripiprazole. These reports are discussed
in the context of previous observations of the potential impact of
aripiprazole on impulse control and the implications such observations could
have for clinical practice and future research.
Pressures to adhere to treatment (‘leverage’) in English mental healthcare
Authors: Burns Tom , Yeeles Ksenija , Molodynski Andrew , Nightingale Helen , Vazquez-Montes Maria , Sheehan Kathleen , Linsell Louise
Published: July 2011

Background

Coercion has usually been equated with legal detention. Non-statutory pressures to adhere to treatment, ‘leverage’, have been identified as widespread in US public mental healthcare. It is not clear if this is so outside the USA.

Aims

To measure rates of different non-statutory pressures in distinct clinical populations in England, to test their associations with patient characteristics and compare them with US rates.

Method

Data were collected by a structured interview conducted by independent researchers supplemented by data extraction from case notes.

Results

We recruited a sample of 417 participants from four differing clinical populations. Lifetime experience of leverage was reported in 35% of the sample, 63% in substance misusers, 33% and 30% in the psychosis samples and 15% in the non-psychosis sample. Leverage was associated with repeated hospitalisations, substance misuse diagnosis and lower insight as measured by the Insight and Treatment Attitudes Questionnaire. Housing leverage was the most frequent form (24%). Levels were markedly lower than those reported in the USA.

Conclusions

Non-statutory pressure to adhere to treatment (leverage) is common in English mental healthcare but has received little clinical or research attention. Urgent attention is needed to understand its variation and place in community practice.
Music therapy for depression: it seems to work, but
how?
Authors: Maratos Anna , Crawford Mike J. , Procter Simon
Published: July 2011

Evidence is beginning to emerge that music therapy can improve the mental
health of people with depression. We examine possible mechanisms of action
of this complex intervention and suggest that music therapy partly is
effective because active music-making within the therapeutic frame offers
the patient opportunities for new aesthetic, physical and relational
experiences.
Pathological gambling: a neurobiological and clinical
update
Authors: Bowden-Jones Henrietta , Clark Luke
Published: July 2011

A proposed merging of pathological gambling with the drug addictions in the
forthcoming DSM-5 prompts an overview of the neurobiological data showing
similarities between these conditions, as well as an update on national
trends in gambling behaviour and current treatment provision.
When does depression become a mental disorder?
Authors: Maj Mario
Published: July 2011

How can we differentiate a depressive disorder from ‘normal’ sadness? This editorial summarises three approaches: the first emphasises the context in which depressive symptoms occur; the second postulates a qualitative difference between the two conditions; and the third argues that the distinction should be based on pragmatic grounds.
Oestrogen receptor polymorphisms and late-life
depression
Authors: Ryan Joanne , Scali Jacqueline , Carrière Isabelle , Peres Karine , Rouaud Olivier , Scarabin Pierre-Yves , Ritchie Karen , Ancelin Marie-Laure
Published: July 2011

Background

Evidence suggests a role for oestrogen in depression but the involvement
of oestrogen receptor polymorphisms remains unknown.

Aims

To determine the association between oestrogen receptor polymorphisms and
late-life depression and the modifying effect of hormone treatment.

Method

Depression was assessed using the Mini-International Neuropsychiatric
Interview, according to DSM-IV criteria and the Centre for Epidemiologic
Studies – Depression Scale. The association between oestrogen receptor α
and β (ER-α and ER-β) polymorphisms with severe depression was examined
in 6017 community-dwelling elderly people using multivariate logistic
regression.

Results

In women, the ER-α rs2234693 and rs9340799 polymorphisms were
significantly associated with the risk of late-life depression. The
A allele of ER-β rs1256049 increased the risk of
depression, but only for non-current users of hormone treatment. In men,
only the ER-β rs4986938 polymorphism showed a weak association with
depression risk.

Conclusions

Oestrogen receptor polymorphisms are associated with severe late-life
depression risk in women only.
Pressures to adhere to treatment: observations on ‘leverage’ in
English mental healthcare
Authors: Zigmond Tony
Published: July 2011

Coercion in psychiatric practice appears to be increasing. Is this in
patients' best interest? Is it good medical practice?
Praying with a patient constitutes a breach of professional boundaries in psychiatric practice
Authors: Poole Rob , Cook Christopher C. H.
Published: July 2011

The extent to which religion and spirituality are integrated into routine psychiatric practice has been a source of increasing controversy over recent years. While taking a patient's spiritual needs into account when planning their care may be less contentious, disclosure to the patient by the psychiatrist of their own religious beliefs or consulting clergy in the context of treatment are seen by some as potentially harmful and in breach of General Medical Council guidance. Here, Professor Rob Poole and Professor Christopher Cook debate whether praying with a patient constitutes a breach of professional boundaries in psychiatric practice.
Facial Nerve Function After Vestibular Schwannoma Surgery Following Failed Conservative Management
Authors: Kaltoft Mikkel , Stangerup Sven-Eric , Caye-Thomasen Per
Published: July 2011

BACKGROUND:

Because only a limited proportion of vestibular schwannomas display growth after diagnosis, an increasing number of patients are managed conservatively. Tumor growth during “wait and scan” may, however, necessitate surgery. In these cases, increased tumor size is likely to increase the risk of impaired facial nerve function after surgery.

OBJECTIVE:

To compare facial nerve function in patients operated on soon after diagnosis with patients allocated to conservative management and the subgroup of these who later had surgery because of tumor growth.

METHODS:

A total of 1378 consecutive patients diagnosed with a vestibular schwannoma 20 mm extrameatal or smaller were included; 419 patients were operated on soon after diagnosis, and 959 patients were initially managed conservatively. In the latter group, 161 patients were subsequently operated on owing to tumor growth.

RESULTS:

All conservatively managed patients had normal facial nerve function at the end of observation. Good facial nerve outcome was found in 87% of patients operated on at diagnosis and in 84% of patients operated on after established tumor growth. For the subgroup of small extrameatal tumors, this difference was significant. When all patients allocated primarily to conservative management were pooled, good facial function was found in 97%, which was significantly better than the result for primary operation (87%).

CONCLUSION:

Overall, conservative management of small to medium-sized vestibular schwannomas is the best option in terms of preservation of facial nerve function. Tumor growth during observation is found in only a minor proportion of the patients, and in these cases, surgery or irradiation should be performed immediately.
Ascending pharyngeal-vertebral anastomosis demonstrated by computed tomography angiography of the ascending pharyngeal artery: a case report
Authors: Sato Yukihisa , Kashiwagi Nobuo , Nakanishi Katsuyuki , Yoshino Kunitoshi , Tomiyama Noriyuki
Published: July 2011

Ascending pharyngeal-vertebral anastomosis has been identified by angiography of the carotid artery in several cases. We present a case of ascending pharyngeal-vertebral anastomosis that was found incidentally in computed tomography angiography of the ascending pharyngeal artery. Images revealed that the anastomosis formed through the hypoglossal branch of the neuromeningeal trunk. The anastomosis seemed to be associated with hypoplasia of the right vertebral artery. Interventional radiologists should be aware of this dangerous anastomotic route of the APA to the VA. Discovery of hypoplasia of the major intracranial arteries before intra-arterial chemotherapy or embolization in head and neck area may avoid subsequent complications.
Epidemiological study on varicose veins in Budapest
Authors: Bihari I , Tornoci L , Bihari P
Published: July 2011

Objective

To analyse the prevalence and risk factors of varicose veins and chronic venous disease in Budapest.

Method

Data were collected using a questionnaire, as well as by performing physical and Doppler ultrasound examination of 566 adult inhabitants of Budapest and some neighbouring villages.

Results

The prevalence of lower-extremity varicose veins was 57.1% in the study population. Verified risk factors include advancing age, pregnancy, jobs requiring a lot of standing, blue-collar work and excess body weight. Neither female gender nor the use of oral contraceptives or hormone replacement therapy was identified as a contributing factor.

Conclusion

Hungarian prevalence data and risk factors seem to be similar to other European countries.
Aberrant medial sural artery causing popliteal vein entrapment syndrome
Authors: Sun Z D Y , Bailey M A , Griffin K J , Coughlin P A , McPherson S J , Scott D J A
Published: July 2011

Isolated popliteal venous entrapment is unusual and often caused by variation or aberrant origins of the gastrocnemius muscle, thickened perivenous fascia or an abnormal vascular bundle. We report a unique case of a fit and well 35-year-old man with popliteal venous entrapment after presenting to the vascular unit with symptomatic varicose veins. The cause of the entrapment was found to be an aberrant medial sural artery on operative exploration. The artery was ligated, releasing the entrapped vein. The patient made an uneventful recovery with resolution of symptoms of venous insufficiency without evidence of muscle ischaemia.
Mechanochemical tumescentless endovenous ablation: final results of the initial clinical trial
Authors: Elias S , Raines J K
Published: July 2011

Objective

The purpose of this study was to assess the safety and efficacy of the ClariVein® system that employs mechanochemical ablation of the great saphenous vein (GSV).

Method

Patients eligible for ablation of the GSV underwent micropuncture access with only local anaesthesia to insert a 4 or 5 Fr sheath. The ClariVein® catheter was placed through the sheath, the wire was extruded, and the distal tip of the wire positioned 2 cm from the saphenofemoral junction under ultrasound guidance. Catheter wire rotation was then activated for 2–3 seconds at approximately 3500 rpm. With the wire rotating, infusion of the sclerosant was started simultaneously with catheter pullback. The sclerosant used was 1.5% liquid sodium tetradecyl sulphate (Sotradecol©, Bioniche Pharma Group, Geneva, Switzerland).

Results

Thirty GSVs in 29 patients were treated. All patients have reached six-month follow-up; the average number of postoperative days is 260. No adverse events have been reported. The Primary Closure Rate is 96.7%.

Conclusion

Mechanochemical ablation appears to be safe and efficacious. The ClariVein® technique eliminates the need for tumescent anaesthesia. The great majority of incompetent GSVs can be treated with this technique.
Optimizing secondary prevention: Statin prescribing across East and West London in accordance with NICE guidelines
Authors: Shakur Rameen , Sathasivam Santron , Yu Chris , Cheung Ivan , Selvakumaran Aran , Anandarajah Cholan , Shakur Amreen , Kaler Mandeep , Mcelligott Geraldine
Published: July 2011

Objectives

Statins are a well-known primary and secondary prevention drug for cardiovascular disease and NICE guidelines have been issued to identify key indicators for their use. An audit looking into statin prescribing for medical inpatients was carried out in two geographically distinct London hospitals.

Design

A prospective inpatient audit of medical prescription charts was performed. Blood results were reviewed for the inpatients during their admission to identify any contraindications for statin usage (rhabdomyolysis). The medical notes were also reviewed for patient refusal of statin therapy.

Setting

The study was carried out at two distinct hospitals in London. Whipps Cross University Hospital (WCUH) and Chelsea & Westminster Hospital (CWH) are located in East London and West London, respectively. Acute medical, surgical, obstetrics and gynaecology, paediatric and palliative wards were excluded.

Participants

A total of 309 inpatient medical notes and prescription chart data were collected from WCUH ( n = 211) and CWH ( n = 98).

Main outcome measures

High percentage of hospitalized patients are not prescribed statins despite clear clinical indications for their use. Regardless of geographical and socioeconomic factors between hospitals, statin prescribing remains suboptimal.

Results

The patient demographics in both hospitals were very similar; the mean age at WCUH was 78 ± 15 1SD while at CWH the mean age was 74± 15 1SD. The results showed that approximately one-third of patients (30% at WCUH and 33% at CWH) had at least one indication for statin therapy according to NICE guidelines and yet they were not prescribed a statin. Ten percent of patients at WCUH and 13% of patients at CWH had ischaemic heart disease (IHD) and yet were not prescribed statins.

Conclusion

Statin prescription is often overlooked in secondary care with patients being discharged without the appropriate assessment (NICE guidelines), which subsequently means repeat prescriptions are not provided by the GP. This study is the first to show that this problem is not due to resources or geography, but is inherent within the NHS system. Consequently, a revised prescription chart checking system has been suggested for pharmacists and junior doctors.
Use of Classical Adsorption Theory to Understand the Dynamic Filtration of Volatile Toxicants in Cigarette Smoke by Active Carbons
Authors: Branton Peter J. , McAdam Kevin G. , Duke Martin G. , Liu Chuan , Curle Maria , Mola Michele , Proctor Christopher J. , Bradley Robert H.
Published: July 2011

The ability of two very different active carbons, a polymer-derived carbon (with ultramicropores and supermicropores, and a large volume of “transport” pores) and a coconut shell-derived carbon (predominantly ultramicroporous), to reduce the levels of volatile toxicants in cigarette smoke has been measured and compared. The polymer-derived carbon was found to be approximately twice as effective in removing the majority of measured smoke vapour-phase toxicants compared to the coconut shell-derived carbon in three different cigarette formats and with two different smoking regimes. Single-component dynamic breakthrough experiments were conducted with benzene, acrylonitrile and 2-butanone at 298 K for beds of each carbon under dry (0% RH) and wet (60% RH) conditions. Longer breakthrough times were found with the polymer-derived carbon, and breakthrough times recorded under wet conditions were found to be up to 20% shorter than those obtained under dry conditions. Correlations between micropore volume, dynamic adsorption volume and filter bed breakthrough time have been demonstrated.
Exchange Character of Caesium Ions onto Zirconium Tungstate
Authors: Sheha R.R. , El-Khouly S.H.
Published: July 2011

Amorphous zirconium tungstate, an inorganic ion-exchanger, was synthesized under optimum conditions and used as a cation-exchange material for the removal of caesium ions from radioactive waste solutions under simulated conditions using batch techniques. The physical and chemical properties of the synthesized ion-exchanger were characterized using Fouriertransform (FT) infrared, X-ray diffraction (XRD) and differential scanning calorimetric (DSC) techniques. Its chemical stability in various mineral acids, bases and organic solvents was also assessed.

The data obtained reveal that the prepared exchanger had a good ionexchange capacity (1.34 mequiv/g towards Cs+ ions) and a high thermal and chemical stability. A hypothetical structural formula, Zr[WO2(OH)2]• 4H2O, was proposed on the basis of chemical composition, FT-IR and thermal analyses. The influences of pH, contact time, initial solute concentration and temperature are reported. Various parameters such as the effective diffusion coefficient under different conditions and the activation energy were determined from the graphical representation of the linearized form of the Arrhenius equation. Thermodynamic parameters such as ΔG0, ΔH0 and ΔS0 were also calculated. The numerical value of ΔG0 increased from 7.43 to 9.74 kJ/mol as the temperature was increased from 298 K to 313 K, indicating that the exchange reaction was more favourable at low temperatures. The negative value of ΔH0 (–49.55 kJ/mol) reflected the exothermic nature of the exchange process.
The Possibility of Balancing VOC Concentration Fluctuations by a Flow through an Activated Carbon Bed
Authors: Červenka Jan , Moravcová Tereza , Obalová Lucie
Published: July 2011

Waste gases from periodic processes often contain VOC concentrations which fluctuate significantly. This causes trouble during their cleaning, for example by thermal destruction. A simple experiment has demonstrated that such concentration fluctuations can be dampened by flowing the polluted gas through a layer of adsorbent. Measurements of balancing the concentration fluctuations of triethylamine (TEA) by flowing through an activated carbon bed showed that balancing average TEA inlet concentrations of 7–30 g/m3 occurs at a superficial velocity lower than 4–0.6 cm/s, which corresponds to a residence time of 37–250 s. An important notion is that balancing the fluctuations may be achieved independently of dividing the time of TEA presence in the inlet air if the given average 8 h TEA concentration at the inlet can be retained.
Removal of Metal Ions from Aqueous Solution Using Trioctyl Phosphine Oxide-Containing Mixed Solvents in Conjunction with a Fibre-Supported Solid Membrane
Authors: Abaji Gaikwad
Published: July 2011

A novel method has been developed for the removal of mercury, arsenic and tin ions using a fibre-supported solid membrane placed between the source phase and the receiving phase which contained trioctyl phosphine oxide (TOPO) in a mixed solvent. The fibre-supported solid membrane was prepared by the esterification of cellulose fibre with tartaric acid at 120deg;C. The experimental variables explored were the initial concentration of the metal ion (10−2 to 10−4 M) in the source phase, the type of mixed solvent employed [containing TOPO, TOPO + acetone, TOPO + tetrahydrofuran, TOPO + 1,4-dioxane, TOPO + methanol, TOPO + ethanol or TOPO + 2-propanol (20–80% v/v)], the concentration of HCl (0.25–1 M) in the receiving phase and the stirring speed (50–130 rpm) of the bulk source and the receiving phase. The efficiency of the organic solvent in the mixed solvent followed the order: TOPO + tetrahydrofuran < TOPO + 1,4-dioxane < TOPO + acetone < TOPO + 2-propanol < TOPO + ethanol < TOPO + methanol > TOPO. The separation of the metal ions was discussed.
Adsorptive Removal of 2,6-Dichlorophenol from Aqueous Solution by Surfactant-Modified Palygorskite Sorbents: Equilibrium, Kinetics and Thermodynamics
Authors: Wang Xue , Pan Jianming , Guan Wei , Zou Xiaohua , Hu Wei , Yan Yongsheng , Li Chunxiang
Published: July 2011

Raw palygorskite was modified by the addition of selected surfactants, viz. hexadecyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB) and octadecyldimethylbenzyl ammonium chloride (ODBAC). These modified clays were used as sorbents for the adsorptive removal of 2,6-dichlorophenol (2,6-DCP) from aqueous solution. Characterization of the sorbents was achieved by Fourier-transform infrared (FT-IR) analysis, nitrogen adsorption/desorption measurements and particle-size analysis. The adsorptive performance of the modified palygorskites towards the removal of 2,6-DCP from aqueous solution was studied by batch methods. In addition, the influence of contact time, pH and temperature on the adsorption process was investigated in detail.

The equilibrium data for the three modified sorbents were well fitted by the Langmuir model. It was found that the monolayer adsorption capacity increased with increasing contact time and solution temperature, respectively. Application of the pseudo-first-order and pseudo-second-order kinetic models to the kinetic data showed that the pseudo-second-order kinetic model provided an excellent fit (R2 > 0.99). In addition, the film diffusion, pore diffusion and intra-particle diffusion models were also used to investigate the adsorption mechanism. Intra-particle diffusional analysis indicated that 2,6-DCP molecules diffused rapidly during the initial adsorption stage, followed by a slower stage and finally the establishment of an equilibrium condition.

Thermodynamic studies showed that the adsorption of 2,6-DCP onto the three sorbents examined occurred spontaneously and that the process was endothermic in nature. The results indicate that the surfactant-modified palygorskite exhibited a significant potential as a sorbent material for the removal of phenolic compounds from aqueous solution.
On the Effect of Modifications to Montmorillonite for the Desulphurization of Synthetic Gasoline
Authors: Zhang Ying , Chen Aiping , Li Chunzhong , Luo Meifang , Xu Zhenliang
Published: July 2011

The preparation, characterization and desulphurization of hexadecyltrimethylammonium bromide (CTAB)-intercalated montmorillonite (CTAB-MMT) and SiO2Ce-pillared montmorillonite (SiO2Ce-MMT) is described. CTAB-MMT, SiO2Ce-MMT and MMT (the original clay) were examined for their ability to remove thiophene sulphur from normal heptane solution as well as from synthetic gasoline. The adsorption thermodynamics and kinetics on all three adsorbents were investigated when it was found that SiO2Ce-MMT possessed a higher adsorption capacity than MMT and CTAB-MMT. The adsorption capacity increased as the temperature increased in the range 303–333 K. The data for the adsorption equilibrium were well fitted by the Freundlich isotherm model. Negative values of ΔG0 suggested that the adsorption process was spontaneous. Furthermore, positive ΔH0 and ΔS0 values indicated that the adsorption was endothermic and irreversible.
The Influence of Stirring upon the Adsorption of a Cationic Surfactant onto Activated Carbon Particles
Authors: Stevenson Paul , Shaw Ryan , Tulloch John , Evans Geoffrey M.
Published: July 2011

The adsorption rate of the cationic surfactant cetyl trimethylammonium bromide (CTAB) onto particles of activated carbon has been determined from measurements of the changes in the conductivity of the supernatant solution. This technique exhibited a high sampling frequency which enabled detailed analysis of the adsorption kinetics. It was demonstrated that the adsorption rate was generally positively correlated with the stirring rate, although the effect was small. The adsorption rate could be modelled by 1.3-order kinetic equations; first-order kinetic treatment only approximately described the process, but gave a better description than second-order kinetics. The hypothesis that adsorption was controlled by the intra-particle diffusion mechanism was not supported by the data. In addition, the technique enabled the construction of adsorption isotherms of ionic surfactants onto particles. In this case, the adsorption equilibrium was described by a Langmuir isotherm.
Developments in Production of Synthetic Fuels Out of Estonian Oil Shale
Authors: Aarna Indrek
Published: July 2011

Estonia is still the world leader in utilization of oil shale. Enefit has cooperated with Outotec to develop a new generation of solid heat carrier technology – Enefit280, which is more efficient, environmentally friendlier and has higher unit capacity. The breakeven price of oil produced in Enefit280 process is competitive with conventional oils. The new technology has advantages that allow easy adaptation to other oil shales around the world. Hydrotreated shale oil liquids have similar properties to crude oil cuts. Design for a shale oil hydrotreater unit can use process concepts, hardware components, and catalysts commercially proven in petroleum refining services.
Managing the Growing Energy Demand: The Case of Egypt
Authors: El-Kholy Hosni , Faried Ragy
Published: July 2011

The electric energy consumption rate in Egypt has an average increase of 7% per year through the last three decades. In order to satisfy the ever increasing energy demand, several actions were, and have to be taken. These actions have to be carried out in parallel. The one having the greatest effect is the measures carried out for energy conservation and loss reduction. Diversifying the energy source such as utilization of Renewable Energy technologies can contribute to satisfying the demand and extending the hydro-carbon reserves life. Regional integration of electrical networks will save expenditures used to build additional power plants.
Strategic Environmental Assessment for Sustainable Expansion of Palm Oil Biofuels in Brazilian North Region
Authors: de Carvalho Carolina Monteiro
Published: July 2011

Biofuels development in Brazil is a key factor for the environment and sustainable development of the country. Brazil has great potential of available areas and has favourable climate and geography for biofuel production, such as palm oil, soy, sugar cane, etc. This research aims to evaluate palm oil production and expansion in Pará state, in the north of Brazil and also Amazonian territory. Degraded land will be evaluated through remote sensing, because palm oil crops should be placed in these lands, and secondly, expansion scenarios would be created. This research will be a decision support tool for public policies.
Mexican Oil Industry: Shifting to Difficult Oil
Authors: Bazán G. Gerardo , González Cristobal J.
Published: July 2011

For many decades Mexico has been considered as one of the most important oil nations in the world. However, in the last few years, Mexico has stepped into an important transition under the light of declining oil fields and new challenging oil projects. The aim of this paper is to show a new perspective of the oil resources that have been exploited throughout the Mexican territory, as well as the remaining resources yet to be exploited. We have developed a resources/production-costs chart that illustrates the historical and future development of the Mexican oil industry, showing the shift that the industry will face in the coming years. The concept for this chart was taken from a model already in use by some of the most prestige energy agencies in the world.
The Future of the Canadian Oil Stands: Engineering and Project Management Advances
Authors: Madden Peter B. , Morawski Jacek D.
Published: July 2011

This paper discusses production technology and project management developments in the Canadian oil sands industry, in the context of AMEC's experience as a consultant and EPCM service provider to lease holders, developers and operators. Mineable and in situ oil sands developments are described, along with methods for and challenges of various production types of in situ, including Cold Flow, Cyclic Steam Stimulation (CSS), Steam Assisted Gravity Drainage (SAGD), Toe to Heel Air Injection (THAI), and VAPEX. Effective project management and supporting systems are critical to achieve cost and schedule targets on large, complex projects performed by AMEC. Workfront planning is essential to achieve optimum construction execution and a best value project. Construction Work Packages (CWPs) divide the work into discrete pieces and the Construction Work Execution Plan influences scheduling of engineering and procurement deliverables. Integration of the schedules and linking to the required on site (ROS) dates of the CWP scopes minimizes workfront duration requirements, allowing progressive completion of systems. AMEC's Engineering Data Warehouse (EDW) works with centrally-hosted, intelligent engineering design tools to assist in achieving tight cost and schedule targets. The EDW ensures all information related to a given piece of equipment is consistent across all systems, supporting quality assurance of engineering data between AMEC, its sub-contractors and supervised contractors. Once verified and consolidated, the information becomes part of a Master Tag Register (MTR), improving AMEC's ability to meet contractual turnover requirements for data quality, completeness and accuracy. Health, safety, security and environmental (HSSE) systems are proactively developed and AMEC's progressive improvement in safety performance over the years is demonstrated. The improvement is due in part to the company's Beyond Zero program, designed to achieve sustainable, world-class HSSE performance.
A Framework for Charaterizing Sound Field Diffusion Based on Scattering Coefficient and Absorption Coefficient of Walls
Authors: Hanyu Toshiki
Published: July 2011

This paper describes the development of a theoretical framework for quantitatively characterizing sound field diffusion based on scattering coefficient and absorption coefficient of walls. The concepts of equivalent scattering area, equivalent scatter reflection area, average scattering coefficient and average scatter reflection coefficient are introduced in order to express all walls' capability of scatter in a room. Using these concepts and the mean free path, scatter-to-absorption ratio, mean scatter time and diffusion time are defined in order to evaluate degree of diffusion of a space. Furthermore the time variation of specular and scattered components in a room impulse response is formulated. The verification of these characterization methods was performed with computer simulations based on the sound ray tracing method. The results supported that the ideas presented are basically valid.
Fast and Accurate Geometric Sound Propagation Using Visibility Computations
Authors: Chandak Anish , Antani Lakulish , Taylor Micah , Manocha Dinesh
Published: July 2011

Geometric Acoustics (GA) techniques based on the image-source method, ray tracing, beam tracing, and ray-frustum tracing, are widely used to compute sound propagation paths. In this paper, we highlight the connection between these propagation techniques with the research on visibility computation in computer graphics and computational geometry. We give a brief overview of visibility algorithms and apply some of these methods to accelerate GA, specifically early specular reflections and finite-edge diffraction. Moreover, we survey our recent work on fast and accurate GA methods that use accurate and conservative visibility techniques. This includes: a) an algorithm for fast computation of early specular reflections using conservative from-point visibility computation; and b) a fast method for finite-edge diffraction using conservative from-region visibility computation. Our approach for computing specular reflections is based on the image-source method and we reduce the number of image sources by using conservative visibility computations. The edge diffraction computation is based on the well known Biot-Tolstoy-Medwin (BTM) diffraction model and we combine it with efficient algorithms for region-based visibility to significantly reduce the number of edge pairs that need to be processed for higher-order diffraction computation. We highlight the performance of these methods on many complex models. Our initial results indicate that we obtain considerable speedups over prior methods for accurate geometric sound propagation.
An Artificial Listener for Assessing Content-Specific Objective Parameters Related to Room Acoustical Quality
Authors: Van Dorp Schuitman J. , de Vries D.
Published: July 2011

A nonlinear, binaural auditory model was developed which is able to act as an artificial listener for assessing features related to the quality of room acoustics. The model is able to derive objective parameters for reverberance, clarity, apparent source width (ASW) and listener envelopment (LEV). In order to derive these parameters, the model splits the input audio into two streams: one related to the source (direct sound) and one related to the environment (room). In order to derive these two streams, the splitting algorithm makes use of the nonlinear properties of the auditory model. The whole algorithm works on arbitrary binaural recordings and therefore the parameters can for example be determined in a concert situation using an artificial head. This way the signal type is automatically taken into account, meaning that the acoustics of a room can be tested for multiple types of stimuli. Listening tests show that the resulting objective parameters correlate highly with perceptual results, even in cases where conventional objective parameters show low correlation coefficients.
Estimation of Reflections from Impulse Responses
Authors: Tervo Sakari , Korhonen Teemu , Lokki Tapio
Published: July 2011

The characteristics of early reflections have a major effect on the acoustics of concert halls. In this article a framework for automatic localization of reflections and their properties is formulated. The framework uses impulse responses measured with multiple microphones. The focus is on the methods that can be used for detecting reflections and the methods that estimate the direction of arrival. Three methods for both tasks are given and their performance is measured using simulated data. Finally an example in a real auditorium is shown using the most reliable methods for detecting and estimating the direction of arrival of the reflections.
In situ Measurement Methods for Characterising Sound Diffusion
Authors: Schmich I. , Brousse N.
Published: July 2011

Two methods have been investigated to define a new way of measuring diffusion in situ. The first one is based on the measurement of a mono-dimensional reverberation time between two parallel plates and gives an evaluation of a scattering coefficient. This field method has been tested through computer simulation and shows high sensitivity to experimental conditions. The experimental set-up has been realized and laboratory measurements conducted. The second method is focused on the scale of a concert hall and proposes new parameters which could lead to a new global diffusivity index. It has been simulated with a computer model with various diffuser arrangements.

These two methods are complementary and if further developed could lead to efficient tools for evaluating and optimizing diffusion in real concert halls.
Application of an Auditory Filter for the Evaluation of Sounds and Sound Fields
Authors: Matsumoto Yuki , Suzuki Masahiro , Ogushi Hisako , Omoto Akira
Published: July 2011

Auditory filters that simulate function of the human auditory organ are introduced for the evaluation of a sound and sound field. Three applications are discussed in this report. The first examines the similarity of sound fields. Music signals convolved with different impulse responses are compared subjectively and quantitatively. The output of the auditory filter indicated high correlations with subjective evaluation. The second example examines the decay process of the sound field, especially in rather dead conditions. Impulse responses measured in recording studios are passed through both an auditory filter and a conventional band-pass filter. Decay processes are then calculated by inverse integration. The responses after passing through the auditory filter show more stable decay curves and the obtained reverberation times are closer to the early decay time, which is closely related to human perceived reverberance. The timbres of musical instruments are used as the third example. The signals from instruments with different means of sound production (such as reed or mouthpiece) are processed by auditory filters and normal band-pass filters. Statistically-obtained characteristics such as kurtosis of the waveform again show higher correlation with subjective evaluation when employing the auditory filter. All the results shown in this report strongly suggest the superiority of an auditory filter in the qualitative evaluation of sounds and sound fields.
Equal Reverberance Contours for Synthetic Room Impulse Responses Listened to Directly: Evaluation of Reverberance in Terms of Loudness Decay Parameters
Authors: Lee Doheon , Cabrera Densil , Martens William L.
Published: July 2011

This paper examines effects of listening level and reverberation time on the perceived decay rate of synthetic room impulse responses (RIRs). A listening test was conducted with synthetic RIRs having a range of listening levels and reverberation times: in the test, subjects adjusted a physical decay rate of the RIRs to match the perceived decay rate of reference stimuli. In this way, we constructed equal reverberance contours as a function of sound pressure level and reverberation time. The experiment results confirm that listening level and reverberation time both significantly affect reverberance. The study also supports our previous finding: that the loudness decay function can be used to predict reverberance better than the conventional reverberance predictors.
Head-Movement-Aware Signal Capture for Evaluation of Spatial Acoustics
Authors: Kim Chungeun , Mason Russell , Brookes Tim
Published: July 2011

This research incorporates the nature of head movement made in listening activities, into the development of a quasi-binaural acoustical measurement technique for the evaluation of spatial impression. A listening test was conducted where head movements were tracked whilst the subjects rated the perceived source width, envelopment, source direction and timbre of a number of stimuli. It was found that the extent of head movements was larger when evaluating source width and envelopment than when evaluating source direction and timbre. It was also found that the locus of ear positions corresponding to these head movements formed a bounded sloped path, higher towards the rear and lower towards the front. This led to the concept of a signal capture device comprising a torso-mounted sphere with multiple microphones. A prototype was constructed and used to measure three binaural parameters related to perceived spatial impression-interaural time and level differences (ITD and ILD) and interaural cross-correlation coefficient (IACC). Comparison of the prototype measurements to those made with a rotating Head and Torso Simulator (HATS) showed that the prototype could be perceptually accurate for the prediction of source direction using ITD and ILD, and for the prediction of perceived spatial impression using IACC. Further investigation into parameter derivation and interpolation methods indicated that 21 pairs of discretely spaced microphones were sufficient to measure the three binaural parameters across the sloped range of ear positions identified in the listening test.
Variation in Oral-Binaural Room Impulse Responses for Horizontal Rotations of a Head and Torso Simulator
Authors: Cabrera Densil , Lee Doheon , Collins Ralph , Hartmann Bastian , Martens William L. , Sato Hayato
Published: July 2011

Oral-binaural room impulse responses (OBRIRs) describe the room acoustical response from the mouth to the ears of a head or dummy head. In this study, we measured OBRIRs in ten rooms, ranging from small to large. In each room, a head and torso simulator (HATS) was rotated at 2 degree increments to sample the room response at the selected measurement position. In rotating the HATS, the radiation pattern of the mouth rotates with the reception pattern of ears. This paper characterises the variation in room gain and interaural response of the tested rooms, and in doing so, we consider how OBRIRs can be usefully understood in terms of acoustical parameters.
The Potential for Phononic Sound Diffusers (PSD)
Authors: Redondo J. , Sánchez-Morcillo Víctor , Picó Rubén
Published: July 2011

Although periodic structures theory gave rise to sound diffusers almost 40 years ago, it has been only in recent years when several authors regarded the possible application of a particular kind of periodic structures, phononic crystals, in the field on room acoustics. This paper explores the possible application of periodic structures used as sound diffusers in rooms. Preliminary simulations, carried out with FDTD, shows that due to the inherent time spreading provided by a periodic structure, they can be used to reduce, or even to eliminate, pernicious effects associated with the low frequency modes of the room.
Open Measurements of Edge Diffraction from a Noise Barrier Scale Model
Authors: Schröder Dirk , Svensson U. Peter , Vorländer Michael
Published: July 2011

Until today, all known simulation methods for the wave phenomenon of edge diffraction are just approximations, based on either Geometrical Acoustics or the numerical solving of the wave equation. Although these methods work fine for simple test scenarios and a certain frequency range, they fail to simulate the effect of diffraction in its whole complexity. This leads to false predictions especially for more complex geometries where the influence of multiple wave diffraction and sound scattering has to be taken into account as well. Consequently, huge effort is currently put into the development of improved simulation methods. Here, a basic need is an all-embracing validation of simulation results, which also includes the comparison with real-world measurements. Unfortunately, there is a lack of such data which is the reason why the Institute of Technical Acoustics (ITA), RWTH Aachen University, Germany, and the Centre for Quantifiable Quality of Service in Communication Systems (Q2S), NTNU Trondheim, Norway, have started an initiative called openMeasurements, which is aimed to be an internet platform for free acoustic measurement data of any kind, together with their respective simulation models (CAD-model, detailed information on sources and receivers, material data) and helpful tools. As initial step, various measurement series of a scaled-down model of a noise barrier were carried out. These series aim to give researches, developers, and common application users, the possibility to thoroughly test their prediction models of edge diffraction.

The measurements were carried out in a full anechoic chamber and a turntable was used to rotate the scale-model during the measurements in steps of one degree. The scale-model was constructed with a changeable ground layer in order to massively influence the object's acoustical properties and, thus, create measurement datasets that considerably differ. Here, datasets for five different ground layers were obtained: 3 absorbers, 1 rigid surface and 1 self-constructed skyline-diffuser. A skyline diffuser was chosen as it is a well reproducible geometrical pattern, which enables a simulation of sound scattering in two ways: stochastic and deterministic. In this contribution, detailed information on the measurement setup is given and measurement procedures are described thoroughly. Measurement uncertainties are briefly discussed and first comparisons with simulations are presented. All measurements together with geometrical models of the scale-model (with/without diffuser), detailed information on sources and receivers, material data (absorption- and scattering coefficients) and useful Matlab tools are freely available for download ( www.openmeasurements.net ).
Introducing Higher Order Diffraction into Beam Tracing Based on the Uncertainty Relation
Authors: Stephenson Uwe M.
Published: July 2011

The neglection of diffraction is still a main problem of ray tracing in room and, even more, in city acoustics. The author's approach to diffraction is an energetic one based on the uncertainty relation (“the closer a sound particle passes an edge the stronger the diffraction effect”). In many numerical experiments, it has been validated quite well at the single screen as well as at the slit as reference cases, compared with Svensson's exact wave-theoretical secondary edge source model. To avoid an explosion of computation time due to the recursive split-up of rays, the long-term objective is to combine this diffraction method with Quantized Pyramidal Beam Tracing which allows a re-unification of beams. For preparation, the sound particle diffraction model has therefore been modified to the more efficient beam diffraction technique and with that has been tested for some additional configurations. Some improved by-pass-distance- and angle-dependent diffraction functions have been investigated. Also the reciprocity principle should be fulfilled. Recent experiments dealt with double diffraction, also at a cascade of two edges. Some new numerical results and comparisons with the reference model are reported. The further aim is to investigate the general applicability of the model to higher order diffraction.
Effect of Sample Size on Measurement of the Absorption by Seats
Authors: Choi YoungJi , Lee JinHak , Joo HyunKyung , Jeong DaeUp
Published: July 2011

This study deals with measurements of the sound absorption by seats which are one of the important parameters in the early design stage in auditorium. In this study, the effects of sample size on measurement of the sound absorption by seats are investigated to define an optimum range of sample size for obtaining reliable measurement results. In the measurements, the absorption coefficients of unoccupied seats at a scale of 1/16 are measured in a 1/5 scale-model of the reverberation chamber based on ISO 354. Various seating blocks having 9 different P/A (perimeter/area of the sample) values ranged from 0.4 to 1.37 m−1 were measured to extrapolate to the absorption coefficients of the larger seating blocks found in a real hall. The predicted results from reverberation chamber measurements were then compared to the measured values in a 1/16 scale-model of the real hall for the validation of this method. The present results show good agreement between values obtained from the hall measurements and those predicted from reverberation chamber measurements.
A Combination of the Sound Particle Simulation Method and the Radiosity Method
Authors: Pohl Alexander , Stephenson Uwe M.
Published: July 2011

In room and urban acoustics, ray tracing as well as, for the reverberation tail, radiosity based simulation methods are in use. Any implementation of diffraction into the sound particle simulation method, i.e. a variant of ray tracing, causes a split-up of sound particles and an explosion of computation time. To prevent that, a re-unification effect of sound energies has to be achieved as known from the radiosity method. For this purpose, the discretization of the walls into small patches is applied to the sound particle simulation method. This combination is called the sound particle radiosity method. In the main part of this paper the efficiency of the presented sound particle radiosity in investigated by deriving a statistical re-unification formula as a function of the main quantization parameter: the patch size. Furthermore the error due to quantization is described as a function of the patch size. It is shown, that smaller patches increase accuracy, but larger patches increase the efficiency. The smearing of echograms due to the receiver size mainly masks the quantization error when the receiver size is at least 10 times the patch size. This investigation, restricted to 2D, serves as a feasibility test for quantized pyramidal beam tracing.