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Alison Pooler,1,2 Roger Beech21School of Nursing and Midwifery, Clinical Education Centre, University Hospital of North Staffordshire NHS Trust, Stoke-on-Trent, UK; 2Health Services Research, Research Institute of Primary Care and Health Sciences, Keele University, Keele, UK Objectives: Exacerbations of chronic obstructive pulmonary disease (COPD) are the third largest cause of emergency hospital admissions in the UK. This systematic literature review explored the relationship between the hospitalization rates and the COPD comorbidities, anxiety, and depression.Methods: The Centre for Research Dissemination's framework for systematic reviews was followed using search terms relating to COPD, anxiety, depression, and hospital admission. Papers identified were assessed for relevance and quality, using a suitable Critical Appraisal Skills Programme tool and Mixed Methods Assessment Tool.Results: Twenty quantitative studies indicated that anxiety and depression led to a statistically significant increase in the likelihood of COPD patients being hospitalized. These comorbidities also led to an increased length of stay and a greater risk of mortality postdischarge. Other significant factors included lower Body-Mass Index, Airflow Obstruction, Dyspnea, and Exercise scores, female gender, lower socioeconomic status, poorer patient perceived quality of life, increased severity of lung function, and less improvement in dyspnea from admission to discharge. It was also highlighted that only 27%–33% of those with depression were being treated for it. Four qualitative studies revealed that patients saw anxiety and depression as a major factor that affected their ability to cope with and self-manage their condition.Implications: Findings from the systematic review have highlighted a need for better recognition and treatment of anxiety and depression amongst individuals with COPD. Ongoing research will develop and test strategies for promoting better management and self-management as a means of reducing hospital admissions.Keywords: COPD, exacerbations, depression, anxiety, hospital admissions

CPP (Current perpendicular-to-plane) magnetotransport measurements have been performed on lithographically patterned magnetic multilayers of NiFeCo/Cu/CoFe/Cu. We implement chemical-mechanical polishing to produce very low Cu-Cu interface resistance that allows accurate, intrinsic giant magnetoresistance (GMR) values to be obtained. Measured GMR is found to be dependent on device size but can be interpreted as the change in the resistivity of the magnetic multilayer and the effects of non-uniform current distribution. Computer simulations account for the non-uniform current distribution and allow us to determine the intrinsic CPP GMR and verify the negligible contact resistance in these structures. Index Terms - CPP GMR, magnetic multilayers, chemical-mechanical polishing, current flow modeling, magnetoelectronic devices.

Calculations which were done for an idealized geometry, showed that exchange coupling around the edge of a sandwich structure formed by folding the top magnetic layer around the edge and connecting to the bottom magnetic layer, increases the field necessary to nucleate the rotational reversal of the edge magnetization by a factor of more than 9. In a more realistic case, the coupling material is likely to be less uniform and somewhat irregular providing an additional contribution to the edge magnetization coercive force. Edge coupling is a major contributor to the high edge coercive force for 'hard edge' sensors. Index Terms--Exchange, GMR head sensors, pinning.

By using a model for giant magnetoresistance (GMR) hysteresis and a model for Barkhausen noise, a magnetic hysteresis model is used to map the effects of magnetic hysteresis on GMR and on accompanying magnetic noise in a GMR magnetic field sensor. Two magnetic noise sources potentially exist in the field sensor: (1) the GMR multilayer material and (2) permalloy field concentrators. The GMR material typically shows a coercivity at H[sub c]≅1 kA/m, much larger than H[sub c]=0.012 kA/m of permalloy. Because permalloy has a very large maximum permeability, it is a much larger magnetic noise source than the GMR material, and would greatly affect sensor operation if operated near H=0. By operating with a bias field well above 1 kA/m, one can operate away from both noise sources. Because the increasing and decreasing arms of the magnetic hysteresis tail of the GMR material are each approximately proportional to |H|[sup 1/2] over a large field range, the model shows that increasing and decreasing portions of the GMR vs H hysteresis curve turn out to be linear, parallel to each other, for the operating field region. If the GMR curve is linear in a region away from H[sub c], a bias field operation in this range would mean that the sensor would not only be nearly noiseless (save for Johnson noise) but also would exhibit linear change in field under an applied field H and could easily be calibrated to measure H. Thus, the modeling points the way to low noise GMR field sensor design. In practice, it is found that biasing at fields halfway down the GMR curve does indeed produce a much quieter measurement than near zero bias field. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Memory cells have been fabricated and tested to demonstrate storage in the pinned layer of a giant magnetoresistance (GMR) spin valve film. The spin valve was top pinned with a FeMn film and gave about 4% GMR ratio. The memory cell consisted of an oblong, 0.6 μm×7.0 μm GMR bit with first metal contacts at each end and a perpendicular first and second metal word line passing over the bit. Joule heating due to current pulses through both the memory cell and the word line raised the temperature of the FeMn pinning layer above its Ne´el point. The magnetic field generated by the word line current switched the pinning direction, depending on the polarity of the word line current. Sense line currents up to 5 mA provided a half select without disturbing the bit. In combination with a 5 mA sense current, the bit was written with a word current pulse of 190 mA. The improved thermal stability of the pinned storage layer memory cell is shown to become necessary as the size of a magnetoresistive memory cell drops below about 0.1 μm×0.4 μm. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

An analysis shows that for pseudospin valve elements with smooth edges, the sense field becomes ineffective in reducing the switching threshold for the thin layer in the body of the element if the element is wider than about 0.35 μm because of domain flexibility. Experimental results at 1.2 μm element width agree with the analysis. The sense field can lower the thresholds in wider elements if the switching is initiated in the tapered ends or in rough edges. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study which examined the analytical properties of giant magnetoresistance read head sensors. Details of the experimental techniques used; Effects of field dependent permeability on head sensors; Elements needed to characterize the magnetoresistance response.