Localized electro-thermal processing: a new route to the patterning of magnetic recording media.

Previous reports have detailed the fabrication of media able to support high density magnetic recording in both longitudinal and perpendicular formats by the global rapid thermal processing of sputtered non-magnetic precursor films. During processing in this manner a magnetic element is released from its nitride and agglomerates to form a random near mono-dispersion of magnetic nano-particles. Here we explore, primarily through modelling and simulation, the feasibility of processing similarly formulated precursor media not globally but locally. We investigate the potential of using conducting nano-probe tips to produce, via electro-thermal (Joule) heating, a nano-patterned recording medium in the form of regular arrays of magnetic islands in a non-magnetic host. In the first instance we concentrate on the simplest cobalt based precursor medium for which both initial simulation and experimental studies indicate the formation of magnetic islands with dimensions of the order of the tip diameter; this is relatively straightforward. The results signify that if practical production scenarios can be devised to produce technologically significant areas of recording media by the rapid multi-probe repetition of this technique, then processing in this manner offers a promising route to areal recording densities of perhaps 5 Terabit/in(2) even with the simplest cobalt media. We also note that the electro-thermal processing method is potentially extendable to the production of a wide variety of magnetic materials (e.g. PtCo, FeCo, NiFe alloys) and, applied via electrical nano-imprinting type techniques, to the production of a wide variety of patterned structures.

Thrombogenicity of radiofrequency ablation procedures: what factors influence thrombin generation?

AIMS: Thromboembolic complications have been reported after radiofrequency ablation but the low incidence of overt clinical events has been a limitation to the study of factors affecting thrombogenic risk. The aim of this study was to determine whether radiofrequency ablation has a procoagulant effect and to examine variables that affect thrombio generation. METHODS AND RESULTS: Thirty-seven consecutive patients who underwent radiofrequency ablation were studied prospectively. Blood samples were assayed for thrombin-antithrombin III (TAT) and d-dimer (DD) at five different time points: (1) baseline; (2) after sheath insertion; (3) after electrophysiological study but before radiofrequency ablation; (4) at completion of the procedure; and (5) 24 h post-procedure. TAT levels were within the normal range at baseline and increased significantly after sheath insertion from 2.1 +/- 1.2 microg l(-1) to 13.3 +/- 16.0 microg l(-1) (P<0.01). Levels increased further to 24.0 +/- 19.9 microg l(-1) (P<0.01) after electrophysiological study but did not increase after radiofrequency ablation. TAT normalized at 24 h. DD increased significantly from baseline values (230.2 +/- 176.8 ng ml(-1)) to 285.4 +/- 237.4 ng ml(-1) (P=0.019) after sheath insertion. There was a further significant increase after electrophysiological study to 423.4 +/- 324.3 ng ml(-1) (P<0.01), and a slight but non-significant increase to 464.4 +/- 307.4 ng ml(-1) after radiofrequency ablation (P=0.159). DD remained elevated at 24 h. Procedure duration was the only variable that correlated with the relative increase in TAT and DD. The patients with the longest procedure durations had more catheters inserted, more radiofrequency applications and largely consisted of accessory bypass tract-mediated tachycardias. Heparin administration significantly blunted the relative increase in TAT after radiofrequency ablation (P=0.005). CONCLUSION: Radiofrequency ablation procedures confer an increased risk of thrombosis. Catheterization and diagnostic study contribute largely to the thrombogenic stimulus. Thrombogenicity is increased in prolonged, complex procedures and is decreased in patients who have been administered heparin during the procedure.

Panic disorder and the heart: a cardiology perspective.

Panic disorder is a common condition that includes symptoms that may masquerade as a primary cardiovascular disorder. In addition, many patients with cardiovascular disease may also have panic disorder. To date, no definitive pathophysiological mechanism for panic disorder has been found; however, there are several hypotheses in the literature. Patients with syndrome X, coronary artery disease and/or palpitations, in addition to panic disorder all present to cardiologists. However, many patients go undiagnosed and ultimately place large costs on the health care system as a result. Panic disorder is a treatable condition, and cardiologists could easily identify patients with panic disorder and initiate appropriate therapy and/or referral.

Leadership-scholarship integration: using the Neuman systems model for 21st-century professional nursing practice.

This article describes leadership and scholarship from the Neuman systems model as requisite for a true practice model necessary for 21st-century scientific professional nursing. A rationale for the integration of leadership and scholarship is provided along with markers to guide the leadership-scholarship protocol, which can be viewed as a scholarly research process. An example from a community nursing center demonstrating the application of the integration of leadership-scholarship is presented to support the proposed integration.

Effects of physiologic pacing versus ventricular pacing on the risk of stroke and death due to cardiovascular causes. Canadian Trial of Physiologic Pacing Investigators.

BACKGROUND: Evidence suggests that physiologic pacing (dual-chamber or atrial) may be superior to single-chamber (ventricular) pacing because it is associated with lower risks of atrial fibrillation, stroke, and death. These benefits have not been evaluated in a large, randomized, controlled trial. METHODS: At 32 Canadian centers, patients without chronic atrial fibrillation who were scheduled for a first implantation of a pacemaker to treat symptomatic bradycardia were eligible for enrollment. We randomly assigned patients to receive either a ventricular pacemaker or a physiologic pacemaker and followed them for an average of three years. The primary outcome was stroke or death due to cardiovascular causes. Secondary outcomes were death from any cause, atrial fibrillation, and hospitalization for heart failure. RESULTS: A total of 1474 patients were randomly assigned to receive a ventricular pacemaker and 1094 to receive a physiologic pacemaker. The annual rate of stroke or death due to cardiovascular causes was 5.5 percent with ventricular pacing, as compared with 4.9 percent with physiologic pacing (reduction in relative risk, 9.4 percent; 95 percent confidence interval, -10.5 to 25.7 percent [the negative value indicates an increase in risk]; P=0.33). The annual rate of atrial fibrillation was significantly lower among the patients in the physiologic-pacing group (5.3 percent) than among those in the ventricular-pacing group (6.6 percent), for a reduction in relative risk of 18.0 percent (95 percent confidence interval, 0.3 to 32.6 percent; P=0.05). The effect on the rate of atrial fibrillation was not apparent until two years after implantation. The observed annual rates of death from all causes and of hospitalization for heart failure were lower among the patients with a physiologic pacemaker than among those with a ventricular pacemaker, but not significantly so (annual rates of death, 6.6 percent with ventricular pacing and 6.3 percent with physiologic pacing; annual rates of hospitalization for heart failure, 3.5 percent and 3.1 percent, respectively). There were significantly more perioperative complications with physiologic pacing than with ventricular pacing (9.0 percent vs. 3.8 percent, P<0.001). CONCLUSIONS: Physiologic pacing provides little benefit over ventricular pacing for the prevention of stroke or death due to cardiovascular causes.

Nocturnal and daytime panic attacks--comparison of sleep architecture, heart rate variability, and response to sodium lactate challenge.

BACKGROUND: The purpose of this study was to determine if nocturnal panic patients have greater autonomic dysregulation than patients with daytime panic. METHODS: Three groups were studied: patients who suffer from panic attacks during sleep (n = 12), those who suffer from daytime panic attacks only (n = 12), and control subjects (n = 12). Each subject underwent 24-hour holter monitoring for heart rate variability (HRV), an overnight sleep recording, and sodium lactate challenge during wakefulness. RESULTS: There was a marked subjective response to the sodium lactate challenge in the panic disorder (PD) patients but not in control subjects. Each group showed changes in HRV in response to sodium lactate challenge. The decrease in HRV measures was more marked in PD patients as a whole than in control subjects. During non-rapid eye movement (REM) sleep the value for total power (TP) was significantly higher in the nocturnal panic patients. The PD patients as a whole had higher values for TP and low-frequency (LF) power during REM sleep than control subjects. There were no significant differences between the two PD groups in sleep architecture. The PD patients as a whole had lower sleep efficiency and less stage 4 sleep than control subjects. CONCLUSIONS: These findings indicate that there are substantial differences between PD and control subjects in autonomic regulation and that there are small differences between patients with daytime panic attacks and those with sleep-related panic attacks.

Responses to caregiving: a reconceptualization using the Roy adaptation model.

Family members who care for chronically ill relatives at home are subject to demands beyond their usual daily responsibilities. These demands can develop into a pattern that disrupts all aspects of the life of the caregiver. The article examines the existing literature on caregiver burden and reconceptualizes the dimensions of caregiver burden within the context of the Roy adaptation model.

The Inventory of Functional Status-Caregiver of a Child in a Body Cast.

The Inventory of Functional Status-Caregiver of a Child in a Body Cast (IFSCCBC), which was derived from the Roy Adaptation Model, includes subscales measuring the extent to which parental caregivers or their surrogates continue their usual household, social and community, childcare, personal care, and occupational activities while caring for a child in a body cast. Content validity was established at 90%. Internal consistency reliability ranged from 0.63 to 0.88, using item to subscale correlations. Subscale to total IFSCCBC score correlations ranged from 0.14 to 0.75. Initial construct validity testing was accomplished by examination of subscale to subscale correlations. The IFSCCBC may be used in research and clinical practice to assess the functional status of parents or their surrogates while they are caring for a child in a body cast.

Shock wave lithotripsy with the Dornier MFL 5000 lithotriptor using an external fixed rate signal.

PURPOSE: We examine the effects of fixed rate shock wave administration on the cardiac rhythm and treatment efficacy of a tubless lithotriptor (Dornier MFL 5000*). A secondary goal was to examine the treatment efficacy of fixed shock wave administration compared to R wave triggered lithotripsy. MATERIALS AND METHODS: In this prospective study Holter monitoring was used before, during and after nonR wave triggered shock wave lithotripsy. RESULTS: An increase in premature ventricular contractions was noted during shock wave lithotripsy. However, there were no episodes of significant ventricular ectopia, ventricular tachycardia, asystole or heart block as a result of nonR wave triggered shock wave administration. NonR wave gated shock wave lithotripsy expedited patient treatment and (mean treatment time 46 +/- 21 minutes)., minimized the use of sedation during treatment and produced results similar to R wave gated shock wave lithotripsy with the MFL 5000 lithotriptor. CONCLUSIONS: With adequate precautions, fixed rate shock wave administration would appear to be a reasonable option to treat urolithiasis with the MFL 5000 lithotriptor as with other newer lithotriptors.

Caring for a young child in a body cast: impact on the care giver.

Data from an open-ended questionnaire and the comments section of a structured questionnaire were combined and analyzed to determine the challenges faced and alterations in usual daily activities required by mothers caring for a young child at home in a body cast. The sample consisted of 35 mothers who identified themselves as the primary care givers of a child in a body cast. The challenges of caring for a child in a body cast required major adjustments in almost every aspect of the mothers' lives, including household activities, social and community activities, child care activities, personal care activities, occupational activities, and educational activities.

Extracorporeal shock wave lithotripsy: multicenter study of kidney and upper ureter versus middle and lower ureter treatments.

Six institutions throughout the United States participated in this study. Each center used a multifunctional flat table lithotriptor (Dornier MFL-5000) to treat 658 patients with kidney and upper ureteral stones (766 treatments) and 323 with middle and lower ureteral stones (391 treatments), for a total of 925 patients (1,157 treatments). Some patients received more than 1 treatment (that is the kidney and ureter), for a total of 981 patient events. Complete followup was available for 81% of the patients. The overall stone-free rate at followup of approximately 90 days was greater in the middle and lower ureter group (83%) than in the kidney and upper ureter group (67%). The proportion of single stones treated was greater for the former group (89.5%) than for the latter group (72%). A larger proportion (18%) of the middle and lower ureter group required 2 or more treatments to the targeted stone than did the kidney and upper ureter group (13%). Anesthesia was required or selected in only 26.7% of the kidney and upper ureteral stone patients and in 18.5% of those with middle and lower ureteral calculi, usually at the request of the patient or physician, or for performance of an adjunctive procedure. The relative safety of this treatment is demonstrated by a low overall rate of complications reported during and after treatment, including a ureteral obstruction rate of 2.1% for kidney and upper ureteral stones and 2.5% for middle and lower ureteral stones. There were no demonstrated trends in a review of laboratory data to suggest significant treatment side effects. The diastolic blood pressure increased to more than 95 mm. Hg after extracorporeal shock wave lithotripsy (ESWL*) in 6% of the kidney and upper ureteral and 4% of the middle and lower ureteral stone patients, while pretreatment hypertension resolved after ESWL in 11% of both groups. The results of this clinical evaluation indicate somewhat greater effectiveness for the specified indications of ESWL of stones in the ureter below the upper rim of the bony pelvis, as opposed to those in the kidney and upper ureter, with a low incidence of complications and side effects.

Efficient storage, computation, and exposure of computer-generated holograms by electron-beam lithography.

An efficient storage format was developed for computer-generated holograms for use in electron-beam lithography. This method employs run-length encoding and Lempel-Ziv-Welch compression and succeeds in exposing holograms that were previously infeasible owing to the hologram's tremendous pattern-data file size. These holograms also require significant computation; thus the algorithm was implemented on a parallel computer, which improved performance by 2 orders of magnitude. The decompression algorithm was integrated into the Cambridge electron-beam machine's front-end processor.Although this provides much-needed ability, some hardware enhancements will be required in the future to overcome inadequacies in the current front-end processor that result in a lengthy exposure time.

Evolution of the technique of combination therapy for staghorn calculi: a decreasing role for extracorporeal shock wave lithotripsy.

Percutaneous nephrostolithotomy with or without extracorporeal shock wave lithotripsy (ESWL) has been extensively used in the management of staghorn calculi, with stone-free rates varying from 23 to 86%. Explanations for the variability of such results include differences in stone burden, differences in percutaneous techniques and an overreliance on ESWL. The results and changing trends in the relative roles of percutaneous nephrostolithotomy and ESWL in the management of staghorn calculi at the Methodist Hospital of Indiana were examined. We reviewed 343 cases of staghorn calculi (partial and complete) with adequate followup data, which were managed with initial percutaneous nephrostolithotomy. Cases were divided into 2 groups: group 1 (252 cases) from 1984 to 1987 when access was performed by a radiologist and group 2 (91 cases) from 1988 to 1990 when access was performed by a urologist. Although stones in group 2 tended to be larger, a decreasing dependence on ESWL was noted (64.7% in group 1 compared to 35.2% in group 2, p less than 0.001). Despite the larger stone size in group 2, stone-free rates were similar (83.3% in group 1, 86.8% in group 2). In groups 1 and 2 percutaneous nephrostolithotomy alone achieved stone-free rates of 91% and 91.5%, respectively. The stone-free rate with the combination approach was 79.1% and 78.1% in groups 1 and 2, respectively. Technical refinements with percutaneous nephrostolithotomy in group 2 include accurate and carefully selected accesses (superior pole in 36.3%) for best approach to the stone, multiple accesses (13.3%) and improved skills in flexible nephroscopy. Blood transfusion has not been required in group 2 compared with 11.1% in group 1. Mean hospital stay was 12.4 days in group 1 and 10.3 days in group 2 (percutaneous nephrostolithotomy alone, 7.2 days). With careful attention to percutaneous nephrostolithotomy techniques, complex renal stones can be successfully managed endourologically, reducing the need for combination ESWL. Complications previously associated with percutaneous nephrostolithotomy have decreased.

Staghorn calculi: analysis of treatment results between initial percutaneous nephrostolithotomy and extracorporeal shock wave lithotripsy monotherapy with reference to surface area.

Treatment recommendations and results reported for the management of staghorn calculi are highly variable. In an attempt to provide a more objective means to compare treatment results for staghorn renal calculi, stone burden as measured by stone surface area was used. Stone surface area was determined by computer analysis. A total of 380 cases of staghorn calculi treated at the same institution was evaluated. Treatment consisted of initial percutaneous nephrostolithotomy with or without extracorporeal shock wave lithotripsy (ESWL*) in 298 cases and ESWL monotherapy in 82. When considered as a group, the overall stone-free rate for initial percutaneous nephrostolithotomy (mean surface area 1,378.3 mm.2) was 84.2% compared to 51.2% (p less than 0.0001) for ESWL monotherapy (mean surface area 693.4 mm.2). For staghorn calculi smaller than 500 mm.2 a stone-free rate of 94.4% was achieved in the percutaneous nephrostolithotomy with or without ESWL group compared to 63.2% for ESWL monotherapy (p = 0.0214). For calculi of 501 to 1,000 mm.2 the stone-free rates were 86% and 45.7%, respectively (p less than 0.0001). When stone surface area exceeded 1,000 mm.2 the stone-free rate for percutaneous nephrostolithotomy with or without ESWL was 82.4% but it was only 22.2% for ESWL monotherapy (p = 0.0002). Overall, when adjusted for stone surface area the odds of being stone-free were more than 8 times higher for initial percutaneous nephrostolithotomy versus ESWL monotherapy (odds ratio = 8.36, p less than 0.0001). While percutaneous nephrostolithotomy with or without ESWL appears to be the procedure of choice for most staghorn stones, ESWL monotherapy may have a role for some stones smaller than 500 mm.2. In 12 such cases associated with a nondilated renal collecting system (mean surface area 380.5 mm.2) a stone-free rate of 91.7% was achieved. The number of procedures required to complete therapy was higher in the initial percutaneous nephrostolithotomy group (2.8 versus 2.1, p less than 0.0001). Although complications were more common in the ESWL monotherapy group (manifested as obstruction in 30.5%), bleeding requiring blood transfusion was more frequent in the initial percutaneous nephrostolithotomy group (9.4%).

Proximal row fusion as a solution for radiocarpal arthritis.

A retrospective study evaluated the function of thirty-six patients treated by radius-scaphoid-lunate arthrodesis for painful posttraumatic radiocarpal arthritis from 1982 through 1987, and determined whether the procedure created arthritis or other functional problems in the remaining joints. Thirty-one men and five women with a mean age of 41 years were studied. The standard surgical technique employed iliac crest bone graft and internal fixation. Seven patients required revision of the proximal fusion to complete wrist fusion because of pain; arthritic changes in the midcarpal joint had been noted in these patients at the time of the limited fusion. The remaining twenty-nine patients required no further surgical treatment. Grip strength averaged 70% of the uninvolved side. The average arc of wrist flexion and extension was forty-eight degrees. Eighteen patients returned to their original employment, in many cases to heavy labor. Five did not return to work because of wrist problems. We conclude that the probability of a good functional result is high for this procedure if there is no midcarpal arthritis.

Four-bone ligament reconstruction for treatment of chronic complete scapholunate separation.

This study reviews the results of a four-bone ligamentous weave reconstruction for treatment of chronic complete scapholunate separation. This reconstruction between the radius, lunate, capitate, and scaphoid employs a dorsal and palmar approach weaving a long strip of the extensor carpi radialis brevis through the four bones reducing and stabilizing the scaphoid and lunate with a wire loop. Thirty-six consecutive cases of operated chronic complete scapholunate separation were evaluated in a 2- to 10-year follow-up. Average length of follow-up was 4.8 years. Average age was 34 years. Average postoperative range of motion was 52 degrees extension and 37 degrees flexion. Grip strength averaged 73% of the noninvolved side. All preoperative scapholunate gaps seen on radiographs were greater than 4 mm, at surgery greater than 1.0 cm, and the postoperative gaps radiographically averaged 3.3 mm. Eighty-six percent of patients returned to preinjury activities including heavy labor. The most significant finding was no x-ray evidence of advancing arthritic changes.