Modelling tribology of slider and disk in a computer hard drive system

Issues of wear and tribology are increasingly important in computer hard drives as slider flying heights are becoming lower and disk protective coatings thinner to minimise spacing loss and allow higher areal density. Friction, stiction and wear between the slider and disk in a hard drive were studied using Accelerated Friction Test (AFT) apparatus. Contact Start Stop (CSS) and constant speed drag tests were performed using commercial rigid disks and two different air bearing slider types. Friction and stiction were captured during testing by a set of strain gauges. System parameters were varied to investigate their effect on tribology at the head/disk interface. Chosen parameters were disk spinning velocity, slider fly height, temperature, humidity and intercycle pause. The effect of different disk texturing methods was also studied. Models were proposed to explain the influence of these parameters on tribology. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) were used to study head and disk topography at various test stages and to provide physical parameters to verify the models. X-ray Photoelectron Spectroscopy (XPS) was employed to identify surface composition and determine if any chemical changes had occurred as a result of testing. The parameters most likely to influence the interface were identified for both CSS and drag testing. Neural Network modelling was used to substantiate results. Topographical AFM scans of disk and slider were exported numerically to file and explored extensively. Techniques were developed which improved line and area analysis. A method for detecting surface contacts was also deduced, results supported and explained observed AFT behaviour. Finally surfaces were computer generated to simulate real disk scans, this allowed contact analysis of many types of surface to be performed. Conclusions were drawn about what disk characteristics most affected contacts and hence friction, stiction and wear.

The Mechanisms of wear of the video head

      This thesis examines the mechanism of wear occuring to the video head and their effect on signal reproduction. in particular it examines the wear occuring to manganese-zinc ferrite heads in sliding contact with iron oxide media.       A literature survey is presented, which covers magnetic recording technologies, focussing on video recording. Existing work on wear of magnetic heads is also examined, and gaps in the theoretical account of wear mechanisms presented in the literature are identified.       Pilot research was carrried out on the signal degradation and wear associated witha number of commercial video tapes, containing a range of head cleaning agents. From this research, the main body of the research was identified. A number of methods of wear measurement were examined for use in this project. Knoop diamond indentation was chosen because experimentation showed it to be capable of measuring wear occuring in situ. This technique was then used to examine the wear associated with different levels of A12O3 and Cr2O3 head cleaning agents.      The results of the research indicated that, whilst wear of the video head increases linearly with increasing HCA content, signal degradation does not vary significantly. The most significant differences in wear and signal reproduction were observed between the two HCAs. The signal degradation of heads worn with tape samples containing A12O3 HCA was found to be lower than heads worn with tapes containing Cr2O3 HCA.      The results also indicate that the wear to the head is an abrasive process characterised by ploughing of the ferrite surface and chipping of the edges of the head gap. Both phenomena appear to be caused by poor iron oxide and head cleaning particles, which create isolated asperities on the tape surface.   

Identifying a novel functional domain within the p115 tethering factor required for Golgi ribbon assembly and membrane trafficking

The tethering factor p115 has been shown to facilitate Golgi biogenesis and membrane traffic in cells in culture. However, the role of p115 within an intact animal is largely unknown. Here, we document that RNAi-mediated depletion of p115 in C. elegans causes accumulation of the yolk protein (YP170) in body cavity and the retention of the yolk receptor RME-2 in the ER and the Golgi within oocytes.Structure-function analyses of p115 have identified two homology (H1-2) regions within the N-terminal globular head and the coiled-coil 1 (CC1) domain as essential for p115 function. We identify a novel C-terminal domain of p115 as necessary for Golgi ribbon formation and cargo trafficking. We show that p115 mutants lacking the fourth CC domain (CC4) act in a dominant negative manner to disrupt Golgi and prevent cargo trafficking in cells containing endogenous p115. Furthermore, using RNAi-mediated "replacement" strategy we show that CC4 is necessary for Golgi ribbon formation and membrane trafficking in cells depleted of endogenous p115.p115 has been shown to bind a subset of ER-Golgi SNAREs through CC1 and CC4 domains (Shorter et al., 2002). Our findings show that CC4 is required for p115 function and suggest that both the CC1 and the CC4 SNARE-binding motifs may participate in p115-mediated membrane tethering.

Investigating the role of capacitive coupling between the operating table and the return electrode of an electrosurgery unit in the modification of the current density distribution within the patients’ body

Background: Electrosurgery units are widely employed in modern surgery. Advances in technology have enhanced the safety of these devices, nevertheless, accidental burns are still regularly reported. This study focuses on possible causes of sacral burns as complication of the use of electrosurgery. Burns are caused by local densifications of the current, but the actual pathway of current within patient's body is unknown. Numerical electromagnetic analysis can help in understanding the issue. Methods: To this aim, an accurate heterogeneous model of human body (including seventy-seven different tissues), electrosurgery electrodes, operating table and mattress was build to resemble a typical surgery condition. The patient lays supine on the mattress with the active electrode placed onto the thorax and the return electrode on his back. Common operating frequencies of electrosurgery units were considered. Finite Difference Time Domain electromagnetic analysis was carried out to compute the spatial distribution of current density within the patient's body. A differential analysis by changing the electrical properties of the operating table from a conductor to an insulator was also performed. Results: Results revealed that distributed capacitive coupling between patient body and the conductive operating table offers an alternative path to the electrosurgery current. The patient's anatomy, the positioning and the different electromagnetic properties of tissues promote a densification of the current at the head and sacral region. In particular, high values of current density were located behind the sacral bone and beneath the skin. This did not occur in the case of non-conductive operating table. Conclusion: Results of the simulation highlight the role played from capacitive couplings between the return electrode and the conductive operating table. The concentration of current density may result in an undesired rise in temperature, originating burns in body region far from the electrodes. This outcome is concordant with the type of surgery-related sacral burns reported in literature. Such burns cannot be immediately detected after surgery, but appear later and can be confused with bedsores. In addition, the dosimetric analysis suggests that reducing the capacity coupling between the return electrode and the operating table can decrease or avoid this problem. © 2013 Bifulco et al.; licensee BioMed Central Ltd.

The benefit of combining standard automated perimetry and multifocal visual evoked potential hemifield intersector analysis in suspecious glaucomatous visual field defects

Several analysis protocols have been tested to identify early visual field losses in glaucoma patients using the mfVEP technique, some were successful in detection of field defects, which were comparable to the standard SAP visual field assessment, and others were not very informative and needed more adjustment and research work. In this study we implemented a novel analysis approach and evaluated its validity and whether it could be used effectively for early detection of visual field defects in glaucoma. The purpose of this study is to examine the benefit of adding mfVEP hemifield Intersector analysis protocol to the standard HFA test when there is suspicious glaucomatous visual field loss. 3 groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes) and glaucoma suspect patients (38 eyes). All subjects had a two standard Humphrey visual field HFA test 24-2, optical coherence tomography of the optic nerve head, and a single mfVEP test undertaken in one session. Analysis of the mfVEP results was done using the new analysis protocol; the Hemifield Sector Analysis HSA protocol. The retinal nerve fibre (RNFL) thickness was recorded to identify subjects with suspicious RNFL loss. The hemifield Intersector analysis of mfVEP results showed that signal to noise ratio (SNR) difference between superior and inferior hemifields was statistically significant between the 3 groups (ANOVA p<0.001 with a 95% CI). The difference between superior and inferior hemispheres in all subjects were all statistically significant in the glaucoma patient group 11/11 sectors (t-test p<0.001), partially significant 5/11 in glaucoma suspect group (t-test p<0.01) and no statistical difference between most sectors in normal group (only 1/11 was significant) (t-test p<0.9). Sensitivity and specificity of the HSA protocol in detecting glaucoma was 97% and 86% respectively, while for glaucoma suspect were 89% and 79%. The use of SAP and mfVEP results in subjects with suspicious glaucomatous visual field defects, identified by low RNFL thickness, is beneficial in confirming early visual field defects. The new HSA protocol used in the mfVEP testing can be used to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patient. Using this protocol in addition to SAP analysis can provide information about focal visual field differences across the horizontal midline, and confirm suspicious field defects. Sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucoma field loss. The Intersector analysis protocol can detect early field changes not detected by standard HFA test.

The role of contingency and gaze direction in the emergence of social referencing

The current study assessed the importance of infant detection of contingency and head and eye gaze direction in the emergence of social referencing. Five- to six-month-old infants' detection of affect-object relations and subsequent manual preferences for objects paired with positive expressions were assessed. In particular, the role of contingency between toys' movements and an actress's emotional expressions as well as the role of gaze direction toward the toys' location were examined. Infants were habituated to alternating films of two toys each paired with an actress's affective expression (happy and fearful) under contingent or noncontingent and gaze congruent or gaze incongruent conditions. Results indicated that gaze congruence and contingency between toys' movements and a person's affective expressions were important for infant perception of affect-object relations. Furthermore, infant perception of the relation between affective expressions and toys translated to their manual preferences for the 3-dimensional toys. Infants who received contingent affective responses to the movements of the toys spent more time touching the toy that was previously paired with the positive expression. These findings demonstrate the role of contingency and gaze direction in the emergence of social referencing in the first half year of life.^

Structure-based modeling of head -related transfer functions towards interactive customization of binaural sound systems

One of the most popular techniques for creating spatialized virtual sounds is based on the use of Head-Related Transfer Functions (HRTFs). HRTFs are signal processing models that represent the modifications undergone by the acoustic signal as it travels from a sound source to each of the listener's eardrums. These modifications are due to the interaction of the acoustic waves with the listener's torso, shoulders, head and pinnae, or outer ears. As such, HRTFs are somewhat different for each listener. For a listener to perceive synthesized 3-D sound cues correctly, the synthesized cues must be similar to the listener's own HRTFs. ^ One can measure individual HRTFs using specialized recording systems, however, these systems are prohibitively expensive and restrict the portability of the 3-D sound system. HRTF-based systems also face several computational challenges. This dissertation presents an alternative method for the synthesis of binaural spatialized sounds. The sound entering the pinna undergoes several reflective, diffractive and resonant phenomena, which determine the HRTF. Using signal processing tools, such as Prony's signal modeling method, an appropriate set of time delays and a resonant frequency were used to approximate the measured Head-Related Impulse Responses (HRIRs). Statistical analysis was used to find out empirical equations describing how the reflections and resonances are determined by the shape and size of the pinna features obtained from 3D images of 15 experimental subjects modeled in the project. These equations were used to yield “Model HRTFs” that can create elevation effects. ^ Listening tests conducted on 10 subjects show that these model HRTFs are 5% more effective than generic HRTFs when it comes to localizing sounds in the frontal plane. The number of reversals (perception of sound source above the horizontal plane when actually it is below the plane and vice versa) was also reduced by 5.7%, showing the perceptual effectiveness of this approach. The model is simple, yet versatile because it relies on easy to measure parameters to create an individualized HRTF. This low-order parameterized model also reduces the computational and storage demands, while maintaining a sufficient number of perceptually relevant spectral cues. ^

An examination of the role of the sports and exercise medicine specialist in Ireland- from epidemiology to treatment

The expansion of the specialty of sports and exercise medicine (SEM) is a relatively recent development in the medical community and the role of the SEM specialist continues to evolve and develop. The SEM specialist is ideally placed to care for all aspects of physical activity not only in athletes but also in the general population. As an advocate for physical activity the SEM specialist plays a broad role in advising safe effective sports and recreation participation; screening for disease related to sports participation; examining and contributing to the evidence behind treatment strategies and evaluating any potential negative impact of sports injury prevention measures. In this thesis I will demonstrate the breadth of the role the Sports and Exercise Medicine Specialist from epidemiology to in-depth examination of treatment strategies. In Chapter 2, I examined the epidemiology of sports and recreation related injury (SRI) in Ireland, an area that has previously been poorly studied. We report on 3,172 SRI (14% of total presentations) presentations to the ED over 6 months. Paediatric patients (4-16 yrs) were over represented comprising 39.9% of all SRI presentation compared to 16% of total ED presentations and 18% of the general population. These injuries were serious (32% fractures) and though 49% of injuries occurred during organised competition/practice, 41.5% occurred during recreation-most often at home. In Chapter 3, I examined risk factors associated with hand injury in hurling. The previous chapter highlighted the importance of a firm evidence base underpinning treatment strategies. When measures to improve welfare are introduced not only must potential benefits be measured, so too must potential unwanted adverse outcomes. In this study I examined a cohort of adult hurlers who had presented to the ED with a hurling related injury in order to highlight the variables associated with hand injury in this population. I found the athletes who wore a helmet were far more likely (OR 3.15 95% CI (1.51-6.56) p= 0.002) to suffer a hand injury than athletes who did not. Very few of those interviewed (4.9%) used hand protection compared to 65% who used helmet and faceguard. The introduction of the helmet and faceguard in hurling has undeniably decreased the incidence of head and face injury in hurling. However in tandem with this intervention several observational studies have demonstrated an increase in the occurrence of hurling related hand injuries. This study highlights the importance of being cognisant of unanticipated or unintended consequences when implementing a new treatment or intervention. In Chapter 4, I examined the role of population screening as applied to sport and exercise. This is a controversial area –cardiac screening in the exercising population has been the subject of much debate. Specifically I define the prevalence of exercise induced bronchoconstriction (EIB) using a specifically designed sports specific field-testing protocol. In this study I found almost a third (29%) of a full international professional rugby squad had confirmed asthma or EIB, as compared with 12-15% of the general population. Despite regular medical screening, 5 ‘new’ untreated cases (12%) were elicited by the challenge test and in the group already on treatment for asthma/EIB; over 50% still displayed EIB. In Chapter 5, I examined the evidence supporting current treatment options for iliotibial band friction syndrome (ITBFS). The practice of sports medicine has traditionally been ‘eminence based’ rather than ‘evidence based’. This may be problematic as some of these practices are based upon flawed principles- for example the treatment of iliotibial band friction syndrome (ITBFS). In this chapter, using cadaveric and biomechanical studies I expand upon the growing base of evidence clarifying the anatomy and biomechanics of the area-thereby re-examining the principles on which current treatments are based. The role of the SEM specialist is broad; we chose to examine specific examples of some of the roles that they execute. An understanding of the epidemiology of SRI presenting to the ED has implications for individual patients, sports governing bodies and health resource utilisation. Population screening is an important tool in health promotion and disease prevention in the general population. Screening in SEM may have similar less well-recognised benefits. The SEM specialist needs to be conversant in screening for medical conditions concerning physical activity. A comprehensive understanding of the pathophysiology of a disease is required for its diagnosis and treatment. Due to the ongoing evolution of SEM many treatments are eminence-based rather than evidence‐based practice. Continued re-examination of the fundamentals of current practice is essential. An awareness of potential unwanted side effects is essential prior to the introduction of any new treatment or intervention. The SEM specialist is ideally placed to advise sports governing bodies on these issues prior to and during their implementation.

Learning and Exploiting Camera Geometry for Computer Vision

This work explores the use of statistical methods in describing and estimating camera poses, as well as the information feedback loop between camera pose and object detection. Surging development in robotics and computer vision has pushed the need for algorithms that infer, understand, and utilize information about the position and orientation of the sensor platforms when observing and/or interacting with their environment.

The first contribution of this thesis is the development of a set of statistical tools for representing and estimating the uncertainty in object poses. A distribution for representing the joint uncertainty over multiple object positions and orientations is described, called the mirrored normal-Bingham distribution. This distribution generalizes both the normal distribution in Euclidean space, and the Bingham distribution on the unit hypersphere. It is shown to inherit many of the convenient properties of these special cases: it is the maximum-entropy distribution with fixed second moment, and there is a generalized Laplace approximation whose result is the mirrored normal-Bingham distribution. This distribution and approximation method are demonstrated by deriving the analytical approximation to the wrapped-normal distribution. Further, it is shown how these tools can be used to represent the uncertainty in the result of a bundle adjustment problem.

Another application of these methods is illustrated as part of a novel camera pose estimation algorithm based on object detections. The autocalibration task is formulated as a bundle adjustment problem using prior distributions over the 3D points to enforce the objects' structure and their relationship with the scene geometry. This framework is very flexible and enables the use of off-the-shelf computational tools to solve specialized autocalibration problems. Its performance is evaluated using a pedestrian detector to provide head and foot location observations, and it proves much faster and potentially more accurate than existing methods.

Finally, the information feedback loop between object detection and camera pose estimation is closed by utilizing camera pose information to improve object detection in scenarios with significant perspective warping. Methods are presented that allow the inverse perspective mapping traditionally applied to images to be applied instead to features computed from those images. For the special case of HOG-like features, which are used by many modern object detection systems, these methods are shown to provide substantial performance benefits over unadapted detectors while achieving real-time frame rates, orders of magnitude faster than comparable image warping methods.

The statistical tools and algorithms presented here are especially promising for mobile cameras, providing the ability to autocalibrate and adapt to the camera pose in real time. In addition, these methods have wide-ranging potential applications in diverse areas of computer vision, robotics, and imaging.

Clean Cookstoves and Health in Samlout, Cambodia

This paper discusses results from a study of the use of cleaner cooking solutions and general health status of people in rural areas from the Battambang province of Cambodia. Data collection included 372 demographic, health and socio-economic surveys with households living in 6 villages in the Samlout district, general health examinations, and measurements of stove use and household concentrations of PM 2.5. The data reveal that health in this population is a major concern, with a very high prevalence of reported abdominal pain, nausea, chronic cough, chest pains, and fever during examinations.  At the household level, we find that clean stove ownership is significantly correlated with the educational status of household head and socio-economic status of a household. Respondents from households with clean stoves appear less likely (though not statistically significantly so) to report household individuals having health problems such as occasional cough, high blood pressure and tuberculosis. Concentrations of PM2.5 are positively correlated with prevalence of occasional cough, high blood pressure and tuberculosis. Based on these results, we advise field testing and evaluation of targeted health interventions in these villages to address the numerous concerns of the local population, including exploring the potential role of clean stoves.

Stimulation of GABAergic neurons of the lateral septum and its effect on movement speed

The lateral septum is associated with the regulation of innate behavior, motivation, and locomotion. Its complex interconnections with cognitive and affective regions such as the hippocampus, hypothalamus, and medial septum have made it an attractive region for studying how motivation regulates behavior in context-specific settings. This GABAergic brain region’s main output is the lateral hypothalamus, which provides downstream signaling of motor commands. Even though stimulation of lateral septum projections to the hypothalamus have shown to decrease running speed in free behaving mice, characterizing movement kinematics due to LS activation has not been studied. GABAergic medium spiny neurons of the lateral septum were selectively activated through the use of optogenetic techniques in transgenic mice. Photostimulation of the lateral septum at theta frequencies caused a non-significant decrease in head and back speed. 3D motion analysis of body movement under photostimulation was quantified, revealing a slow, linear decrease of body speed as photostimulation progressed. These results support the role of lateral septum activation in movement regulation and shed light on the specific manner in which stimulation of the LS gradually decreases movement speed.

Magnetic Theory and Applications in the Naples Bay (Southern Tyrrhenian Sea, Italy): Magnetic Anomaly Fields and Relationships with Morpho-Structural Lineaments

Magnetic theory and application to a complex volcanic area located in Southern Italy are here discussed showing the example of the Gulf of Naples, located at Southern Italy Tyrrhenian margin. A magnetic anomaly map of the Gulf of Naples has been constructed aimed at highlighting new knowledge on geophysics and volcanology of this area of the Eastern Tyrrhenian margin, characterized by a complex geophysical setting, strongly depending on sea bottom topography. The theoretical aspects of marine magnetometry and multibeam bathymetry have been discussed. Magnetic data processing included the correction of the data for the diurnal variation, the correction of the data for the offset and the leveling of the data as a function of the correction at the cross-points of the navigation lines. Multibeam and single-beam bathymetric data processing has been considered. Magnetic anomaly fields in the Naples Bay have been discussed through a detailed geological interpretation and correlated with main morpho-structural features recognized through morphobathymetric interpretation. Details of magnetic anomalies have been selected, represented and correlated with significant seismic profiles, recorded on the same navigation lines of magnetometry. They include the continental shelf offshore the Somma-Vesuvius volcanic complex, the outer shelf of the Gulf of Pozzuoli offshore the Phlegrean Fields volcanic complex, the relict volcanic banks of Pentapalummo, Nisida and Miseno, the Gaia volcanic bank on the Naples slope, the western slope of the Dohrn canyon, the Magnaghi canyon’s head and the magnetic anomalies among the Ischia and Procida islands.

Long-term assessment of wild boar harvesting and cattle removal for bovine tuberculosis control in free ranging populations

Wild boar is a recognized reservoir of bovine tuberculosis (TB) in the Mediterranean ecosystems, but information is scarce outside of hotspots in southern Spain. We describe the first high-prevalence focus of TB in a non-managed wild boar population in northern Spain and the result of eight years of TB management. Measures implemented for disease control included the control of the local wild boar population through culling and stamping out of a sympatric infected cattle herd. Post-mortem inspection for detection of tuberculosis-like lesions as well as cultures from selected head and cervical lymph nodes was done in 745 wild boar, 355 Iberian ibexes and five cattle between 2004 and 2012. The seasonal prevalence of TB reached 70% amongst adult wild boar and ten different spoligotypes and 13 MIRU-VNTR profiles were detected, although more than half of the isolates were included in the same clonal complex. Only 11% of infected boars had generalized lesions. None of the ibexes were affected, supporting their irrelevance in the epidemiology of TB. An infected cattle herd grazed the zone where 168 of the 197 infected boars were harvested. Cattle removal and wild boar culling together contributed to a decrease in TB prevalence. The need for holistic, sustained over time, intensive and adapted TB control strategies taking into account the multi-host nature of the disease is highlighted. The potential risk for tuberculosis emergence in wildlife scenarios where the risk is assumed to be low should be addressed.

Conflict resolution strategies : influence of organizational and professional commitment nurses

Introduction: The changes in the health area and the set of structural changes in the nursing profession and career interfere in the dynamics and stability of the future of the nurses. Objectives: To study the influence of organizational and professional commitment of the nurses in the strategies of conflict resolution. Methods: This is a quantitative, transversal and non-experimental research, following a descriptive-correlational way. Data were obtained by applying a questionnaire to nurses that work on different types of Primary Health Care Units. As measuring instruments we used three scales that grouped a total of nine subscales used to evaluate: the organizational commitment, the professional commitment and the strategies of conflict resolution. Results: The majority of nurses present moderate scores of organizational and Professional commitment with higher affective commitment to the normative commitment or instrumental commitment and feel that nursing is an interesting and challenging profession, but personal and social perception of nursing relevance is moderately weak. Nurses adopt the domination conflict resolution strategies and accommodation over the head and less integrative strategies and commitment. With subordinates more nurses adopt the avoidance strategy. When the conflictual situation arises with colleagues more endow the integrative strategies and commitment and less domination strategy. The organizational and professional commitment is significantly associated with some solving strategies conflict adopted by nurses as the conflictual situation arises with the boss, with subordinates or colleagues. Some dimensions of organizational commitment and professional foretell to significantly shape the adoption of conflict resolution strategy adopted.

Candidíase sistêmica com localização encefálica: estudo anátomo-clínico de cinco casos

Central nervous system involvement in Candida septicaemia is rare and not more than four cases have been published in Brazil. Five new cases of systemic candidiasis with cerebral lesions are reported. All patients (four adults and a child) had serious underlying diseases and were submitted to heavy long-term antibiotic therapy with multiple drugs. Seizures in one case and neck stiffness in another were the only neurologic signs that could be attributed to candidiasis. In no case were the lesions severe enough to be considered an immediate cause of death. In three patients, no macroscopic changes were evident in the brain, but microabscesses and granulomata were observed on microscopical examination; another patient had two gross areas with necrotic and haemorrhagic appearance in the cerebral hemispheres; the child had only two microscopic granulomata. The aetiological agent was demonstrated by Grocott's methenamine silver technique in all cases. Involvement of organs other than the central nervous system could be demonstrated in three autopsies. Discussion is confined mainly to such aspects as the contributory factors in the pathogenesis of systemic candidiasis as well as the marked rise in the incidence of this condition in the past few decades. It is suggested that the frequence of monilial septicaemia in Brazil may be far more serious than apparent from the scarcity of reported cases.