Spatial Hearing with Simultaneous Sound Sources: A Psychophysical Investigation

This thesis provides an overview of work conducted to investigate human spatial hearing in situations involving multiple concurrent sound sources. Much is known about spatial hearing with single sound sources, including the acoustic cues to source location and the accuracy of localisation under different conditions. However, more recently interest has grown in the behaviour of listeners in more complex environments. Concurrent sound sources pose a particularly difficult problem for the auditory system, as their identities and locations must be extracted from a common set of sensory receptors and shared computational machinery. It is clear that humans have a rich perception of their auditory world, but just how concurrent sounds are processed, and how accurately, are issues that are poorly understood. This work attempts to fill a gap in our understanding by systematically examining spatial resolution with multiple sound sources. A series of psychophysical experiments was conducted on listeners with normal hearing to measure performance in spatial localisation and discrimination tasks involving more than one source. The general approach was to present sources that overlapped in both frequency and time in order to observe performance in the most challenging of situations. Furthermore, the role of two primary sets of location cues in concurrent source listening was probed by examining performance in different spatial dimensions. The binaural cues arise due to the separation of the two ears, and provide information about the lateral position of sound sources. The spectral cues result from location-dependent filtering by the head and pinnae, and allow vertical and front-rear auditory discrimination. Two sets of experiments are described that employed relatively simple broadband noise stimuli. In the first of these, two-point discrimination thresholds were measured using simultaneous noise bursts. It was found that the pair could be resolved only if a binaural difference was present; spectral cues did not appear to be sufficient. In the second set of experiments, the two stimuli were made distinguishable on the basis of their temporal envelopes, and the localisation of a designated target source was directly examined. Remarkably robust localisation was observed, despite the simultaneous masker, and both binaural and spectral cues appeared to be of use in this case. Small but persistent errors were observed, which in the lateral dimension represented a systematic shift away from the location of the masker. The errors can be explained by interference in the processing of the different location cues. Overall these experiments demonstrated that the spatial perception of concurrent sound sources is highly dependent on stimulus characteristics and configurations. This suggests that the underlying spatial representations are limited by the accuracy with which acoustic spatial cues can be extracted from a mixed signal. Three sets of experiments are then described that examined spatial performance with speech, a complex natural sound. The first measured how well speech is localised in isolation. This work demonstrated that speech contains high-frequency energy that is essential for accurate three-dimensional localisation. In the second set of experiments, spatial resolution for concurrent monosyllabic words was examined using similar approaches to those used for the concurrent noise experiments. It was found that resolution for concurrent speech stimuli was similar to resolution for concurrent noise stimuli. Importantly, listeners were limited in their ability to concurrently process the location-dependent spectral cues associated with two brief speech sources. In the final set of experiments, the role of spatial hearing was examined in a more relevant setting containing concurrent streams of sentence speech. It has long been known that binaural differences can aid segregation and enhance selective attention in such situations. The results presented here confirmed this finding and extended it to show that the spectral cues associated with different locations can also contribute. As a whole, this work provides an in-depth examination of spatial performance in concurrent source situations and delineates some of the limitations of this process. In general, spatial accuracy with concurrent sources is poorer than with single sound sources, as both binaural and spectral cues are subject to interference. Nonetheless, binaural cues are quite robust for representing concurrent source locations, and spectral cues can enhance spatial listening in many situations. The findings also highlight the intricate relationship that exists between spatial hearing, auditory object processing, and the allocation of attention in complex environments

Bedrijfsduurzaamheidindex hoog op het lagekostenbedrijf

Door de BedrijfsDuurzaamheidIndex (BDI) is duurzaamheid op melkveebedrijven meetbaar gemaakt. De BDI is voor het eerst berekend op de praktijkcentra van het Praktijkonderzoek. Het Lagekostenbedrijf haalt een goede score voor bijna alle onderdelen van duurzaamheid. Alleen voor de landschappelijke waarde kunnen verbeteringen worden geboekt. De strategie van het Lagekostenbedrijf leidt tot een goede score voor de BDI

Centaur 1952

Digitised by the Faculty of the Veterinary Scienc

Clinical characteristics of women captured by extending the definition of severe postpartum haemorrhage with 'refractoriness to treatment': a cohort study

Background: The absence of a uniform and clinically relevant definition of severe postpartum haemorrhage hampers comparative studies and optimization of clinical management. The concept of persistent postpartum haemorrhage, based on refractoriness to initial first-line treatment, was proposed as an alternative to common definitions that are either based on estimations of blood loss or transfused units of packed red blood cells (RBC). We compared characteristics and outcomes of women with severe postpartum haemorrhage captured by these three types of definitions. Methods: In this large retrospective cohort study in 61 hospitals in the Netherlands we included 1391 consecutive women with postpartum haemorrhage who received either ≥4 units of RBC or a multicomponent transfusion. Clinical characteristics and outcomes of women with severe postpartum haemorrhage defined as persistent postpartum haemorrhage were compared to definitions based on estimated blood loss or transfused units of RBC within 24 h following birth. Adverse maternal outcome was a composite of maternal mortality, hysterectomy, arterial embolisation and intensive care unit admission. Results: One thousand two hundred sixty out of 1391 women (90.6%) with postpartum haemorrhage fulfilled the definition of persistent postpartum haemorrhage. The majority, 820/1260 (65.1%), fulfilled this definition within 1 h following birth, compared to 819/1391 (58.7%) applying the definition of ≥1 L blood loss and 37/845 (4.4%) applying the definition of ≥4 units of RBC. The definition persistent postpartum haemorrhage captured 430/471 adverse maternal outcomes (91.3%), compared to 471/471 (100%) for ≥1 L blood loss and 383/471 (81.3%) for ≥4 units of RBC. Persistent postpartum haemorrhage did not capture all adverse outcomes because of missing data on timing of initial, first-line treatment. Conclusion: The definition persistent postpartum haemo

Non-AIDS defining cancers in the D:A:D Study-time trends and predictors of survival : a cohort study

BACKGROUND:Non-AIDS defining cancers (NADC) are an important cause of morbidity and mortality in HIV-positive individuals. Using data from a large international cohort of HIV-positive individuals, we described the incidence of NADC from 2004-2010, and described subsequent mortality and predictors of these.METHODS:Individuals were followed from 1st January 2004/enrolment in study, until the earliest of a new NADC, 1st February 2010, death or six months after the patient's last visit. Incidence rates were estimated for each year of follow-up, overall and stratified by gender, age and mode of HIV acquisition. Cumulative risk of mortality following NADC diagnosis was summarised using Kaplan-Meier methods, with follow-up for these analyses from the date of NADC diagnosis until the patient's death, 1st February 2010 or 6 months after the patient's last visit. Factors associated with mortality following NADC diagnosis were identified using multivariable Cox proportional hazards regression.RESULTS:Over 176,775 person-years (PY), 880 (2.1%) patients developed a new NADC (incidence: 4.98/1000PY [95% confidence interval 4.65, 5.31]). Over a third of these patients (327, 37.2%) had died by 1st February 2010. Time trends for lung cancer, anal cancer and Hodgkin's lymphoma were broadly consistent. Kaplan-Meier cumulative mortality estimates at 1, 3 and 5 years after NADC diagnosis were 28.2% [95% CI 25.1-31.2], 42.0% [38.2-45.8] and 47.3% [42.4-52.2], respectively. Significant predictors of poorer survival after diagnosis of NADC were lung cancer (compared to other cancer types), male gender, non-white ethnicity, and smoking status. Later year of diagnosis and higher CD4 count at NADC diagnosis were associated with improved survival. The incidence of NADC remained stable over the period 2004-2010 in this large observational cohort.CONCLUSIONS:The prognosis after diagnosis of NADC, in particular lung cancer and disseminated cancer, is poor but has improved somewhat over time. Modifiable risk factors, such as smoking and low CD4 counts, were associated with mortality following a diagnosis of NADC

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Adding a second surprise question triggers general practitioners to increase the thoroughness of palliative care planning: results of a pilot RCT with cage vignettes

Contains fulltext : 191169.pdf (publisher's version ) (Open Access

The view of pulmonologists on palliative care for patients with COPD: a survey study

Contains fulltext : 175672.pdf (publisher's version ) (Open Access)INTRODUCTION: Early palliative care is not a common practice for patients with COPD. Important barriers are the identification of patients for palliative care and the organization of such care in this patient group. OBJECTIVE: Pulmonologists have a central role in providing good quality palliative care for patients with COPD. To guide future research and develop services, their view on palliative care for these patients was explored. METHODS: A survey study was performed by the members of the Netherlands Association of Physicians for Lung Diseases and Tuberculosis. RESULTS: The 256 respondents (31.8%) covered 85.9% of the hospital organizations in the Netherlands. Most pulmonologists (92.2%) indicated to distinguish a palliative phase in the COPD trajectory, but there was no consensus about the different criteria used for its identification. Aspects of palliative care in COPD considered important were advance care planning conversation (82%), communication between pulmonologist and general practitioner (77%), and identification of the palliative phase (75.8%), while the latter was considered the most important aspect for improvement (67.6%). Pulmonologists indicated to prefer organizing palliative care for hospitalized patients with COPD themselves (55.5%), while 30.9% indicated to prefer cooperation with a specialized palliative care team (SPCT). In the ambulatory setting, a multidisciplinary cooperation between pulmonologist, general practitioner, and a respiratory nurse specialist was preferred (71.1%). CONCLUSION: To encourage pulmonologists to timely initiate palliative care in COPD, we recommend to conduct further research into more specific identification criteria. Furthermore, pulmonologists should improve their skills of palliative care, and the members of the SPCT should be better informed about the management of COPD to improve care during hospitalization. Communication between pulmonologist and general practitioner should be emphasized in training to improve palliative care in the ambulatory setting

Global environmental change and land use

xi, 210 hal; 24,5 c

The relationship of fatigue in breast cancer survivors with quality of life and factors to address in psychological interventions: A systematic review

Item does not contain fulltextSevere fatigue occurs in one in four breast cancer survivors (BCS). Quality of life (QOL) and psychological factors are important in fatigue-oriented interventions for BCS, but an up-to-date overview is lacking. The aims of this review were to (i) provide a comprehensive overview of the relationship of fatigue with QOL and factors that can be addressed in psychological interventions for fatigue in BCS and (ii) determine the strength of evidence for these relationships. A systematic literature search was conducted to find studies on fatigue in BCS who had completed curative breast cancer treatment. Fatigue-related factors of 57 eligible studies were extracted and the level of evidence was determined. Factors regarding QOL (ie, general QOL, functioning, work ability, and mental health) had a negative relationship with fatigue (moderate to strong evidence). Target factors for psychological interventions were divided into the subcategories emotional problems, sleep disturbances, physical activity, pain, coping with cancer, dysfunctional cognitions, and social support. Moderate to strong evidence appeared for a relationship of fatigue with depressive symptoms, anxiety, distress, sleep disturbances, lower physical activity levels, pain, difficulties with coping with cancer, and catastrophizing about symptoms. These factors are points of attention for existing and future psychological interventions for fatigue in BCS