Information loss.

The complete gravitational collapse of a body in general relativity will result in the formation of a black hole. Although the black hole is classically stable, quantum particle creation processes will result in the emission of Hawking radiation to infinity and corresponding mass loss of the black hole, eventually resulting in the complete evaporation of the black hole. Semiclassical arguments strongly suggest that, in the process of black hole formation and evaporation, a pure quantum state will evolve to a mixed state, i.e. there will be 'information loss'. There has been considerable controversy over this issue for more than 40 years. In this review, we present the arguments in favor of information loss, and analyze some of the counter-arguments and alternative possibilities.

Impact of a Mandated Accreditation Process on 1,045 Registered Echocardiographic Service Providers in a Previously Unregulated, Publicly Funded Environment.

BACKGROUND: This review was undertaken to examine the impact of a standards-based, mandated accreditation process on several aspects of echocardiographic service delivery in a single-payer, previously unregulated environment. METHODS: In the province of Ontario, virtually all echocardiographic services are funded by the Ministry of Health and Long Term Care. The Echocardiography Quality Improvement (EQI) process was introduced in 2012 and subsequently linked formally to reimbursement in 2016. Previously, payment for echocardiographic services in Ontario was unregulated. The impact of EQI on the number of facilities, echocardiographic volumes, costs, quality standards, and physician service provision were compared before and after implementation. RESULTS: Of the initial 1,045 registrants, 604 (57.8%) have been accredited or accreditation is expected having successfully resolved identified deficiencies. The remaining registrants were either never functionally operating (323 [30.9%]) or have withdrawn services (118 [11.3%]) since mandatory registration became a requirement for reimbursement. A number of factors identified facilities that were able to most promptly meet EQI standards, including hospital-based, academic, and multiple-physician facilities. The average annual increase in the utilization of echocardiographic services before EQI was 6.7%, decreasing to 2.7% since. The proportion of repeat examinations decreased in community-based facilities. Since 2013, costs for echocardiographic services have totaled about $92.3 million less than predicted by pre-2012 trends. To address standards, some small, more isolated facilities sought out alliances with larger facilities, particularly those affiliated with academic hospitals. CONCLUSIONS: EQI is demonstrably a means for improving quality while reducing the rate of growth and repeat examinations.

Cardiovascular Response to Recreational Hockey in Middle-Aged Men.

The present study examined the hemodynamic response to recreational pick-up hockey relative to maximal exercise testing in middle-aged men. A total of 23 men with a mean age of 53 ± 7 years were studied. Graded exercise testing on a cycle ergometer determined maximal oxygen consumption, blood pressure (BP), and heart rate (HR). Ambulatory BP and Holter electrocardiographic monitoring was performed during one of their weekly hockey games (mean duration = 45 ± 7.2 minutes): for "On-Ice" responses (PLAY; data recorded while standing immediately after a shift; 8.0 ± 1.4 shifts per game) and during seated recovery (BENCH), 15 minutes after the game. On-Ice HRs and BPs were significantly higher than values obtained during maximal cycle exercise, respectively (HR 174 ± 8.9 vs 163 ± 11.0 beats/min) (systolic blood pressure 202 ± 20 vs 173 ± 31 mm Hg; p <0.05). Both systolic and diastolic blood pressures decreased significantly throughout the duration of the game, whereas HR increased from 139 ± 20 to 155 ± 16 beats/min during the game. The myocardial oxygen demand (myocardial time tension index) increased significantly during PLAY concurrent with a decrease in estimated myocardial oxygen supply (diastolic pressure time index), with the endocardial viability ratio during PLAY demonstrating a significant decrease during the third quarter of the game (1.25 ± 0.24) versus the first quarter (1.56 ± 0.30), which remained depressed 15 minutes post-game (p <0.05). In conclusion, recreational pick-up hockey in middle-aged men is an extremely vigorous interval exercise with increasing relative intensity as the game progresses. Hockey elicits peak BPs and HRs that can exceed values observed during maximal exercise testing and is characterized by progressive increases in myocardial oxygen demand and lowered supply during PLAY and BENCH time. Given the progressive and high cardiovascular demands, caution is warranted when estimating the cardiovascular demands of hockey from clinical stress testing, particularly in those whom coronary reserve may be compromised.

Cardiac resynchronization therapy: an option for inotrope-supported patients with end-stage heart failure?

BACKGROUND: Patients with refractory heart failure requiring inotropic support have a very poor prognosis. Cardiac resynchronization therapy (CRT) offers symptomatic and possibly a survival benefit for patients with stable chronic heart failure (CHF) and a prolonged QRS, but its role in the management of end-stage heart failure requiring inotropic support has not been evaluated. METHODS: We performed a retrospective observational study of patients undergoing CRT at our institution. RESULTS: We identified 10 patients who required inotropic support for refractory CHF and who underwent CRT while on intravenous inotropic agents. Patients had been in hospital for 30+/-29 days and had received inotropic support for 11+/-6 days prior to CRT. All patients were weaned from inotropic support (2+/-2 days post-CRT) and all patients survived to hospital discharge (12+/-13 days post-CRT). Furosemide dose fell from 160+/-38 mg on admission to 108+/-53 mg on discharge (p<0.01). Serum creatinine fell from 192+/-34 micromol/l prior to CRT to 160+/-37 micromol/l on discharge (p<0.05). Serum sodium was 131+/-4 mmol/l prior to CRT and remained low at 132+/-5 mmol/l on discharge. At short-term follow up (mean 47 days), all patients were alive; mean furosemide dose was 130+/-53 mg (p=0.056 versus pre-CRT). Serum creatinine was 157+/-36 micromol/l and serum sodium had increased to 138+/-6 mmol/l (p<0.05 and p<0.01, respectively, versus pre-CRT). CONCLUSION: CRT may offer a new therapeutic option for inotrope-supported CHF patients with a prolonged QRS.

The Thermodynamics of Black Holes.

We review the present status of black hole thermodynamics. Our review includes discussion of classical black hole thermodynamics, Hawking radiation from black holes, the generalized second law, and the issue of entropy bounds. A brief survey also is given of approaches to the calculation of black hole entropy. We conclude with a discussion of some unresolved open issues.

A randomized controlled trial of the embrace advanced scar therapy device to reduce incisional scar formation.

BACKGROUND: Scarring represents a significant biomedical burden in clinical medicine. Mechanomodulation has been linked to scarring through inflammation, but until now a systematic approach to attenuate mechanical force and reduce scarring has not been possible. METHODS: The authors conducted a 12-month, prospective, open-label, randomized, multicenter clinical trial to evaluate abdominoplasty scar appearance following postoperative treatment with the embrace Advanced Scar Therapy device to reduce mechanical forces on healing surgical incisions. Incisions from 65 healthy adult subjects were randomized to receive embrace treatment on one half of an abdominoplasty incision and control treatment (surgeon's optimal care methods) on the other half. The primary endpoint for this study was the difference between assessments of scar appearance for the treated and control sides using the visual analogue scale scar score. RESULTS: Final 12-month study photographs were obtained from 36 subjects who completed at least 5 weeks of dressing application. The mean visual analogue scale score for embrace-treated scars (2.90) was significantly improved compared with control-treated scars (3.29) at 12 months (difference, 0.39; 95 percent confidence interval, 0.14 to 0.66; p = 0.027). Both subjects and investigators found that embrace-treated scars demonstrated significant improvements in overall appearance at 12 months using the Patient and Observer Scar Assessment Scale evaluation (p = 0.02 and p < 0.001, respectively). No serious adverse events were reported. CONCLUSIONS: These results demonstrate that the embrace device significantly reduces scarring following abdominoplasty surgery. To the authors' knowledge, this represents the first level I evidence for postoperative scar reduction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Standards for provision and accreditation of echocardiography in Ontario.

In March of 2010, the Ontario Ministry of Health and Long-term Care and Ontario Medical Association jointly commissioned a Working Group to make recommendations regarding the provision and accreditation of echocardiographic services in Ontario. That commission undertook a process to examine all aspects of the provision, reporting and interpretation of echocardiographic examinations, including the echocardiographic examination itself, facilities, equipment, reporting, indications, and qualifications of personnel involved in the acquisition and interpretation of studies. The result was development of a set of 54 performance standards and a process for accreditation of echocardiographic facilities, initially on a voluntary basis, but leading to a process of mandatory accreditation. This article, and its accompanying Supplemental Material, outline the mandate, process undertaken, standards developed, and accreditation process recommended.

Biventricular pacing: impact on exercise-induced increases in mitral insufficiency in patients with chronic heart failure.

INTRODUCTION: Mitral regurgitation (MR) in chronic heart failure (CHF) patients frequently worsens with exercise. Cardiac resynchronization therapy (CRT) reduces MR at rest, but its effects on exercise-induced worsening of MR are incompletely explored. The present study examined the influence of CRT on MR during submaximal exercise in CHF patients. METHODS: Eleven patients with CHF who were treated with CRT underwent echocardiography while performing steady-state exercise during four conduction modes (intrinsic rhythm, right ventricular [RV], biventricular [BiV] and left ventricular [LV] pacing). Measurements of MR were jet area planimetry, effective regurgitant orifice area, peak MR flow rate and regurgitant volume. RESULTS: At rest and during exercise, there were no differences in dyssynchrony between intrinsic rhythm and RV pacing. BiV and LV pacing reduced dyssynchrony at rest and during exercise compared with intrinsic conduction and RV pacing, and there were no differences in the magnitude of these effects between these two pacing modes. At rest, RV pacing increased MR compared with intrinsic conduction (MR regurgitant volume; P<0.05), whereas BiV and LV pacing reduced MR (reductions in effective regurgitant orifice area and jet area; P<0.02, and MR flow rate; P<0.05 with BiV pacing from intrinsic conduction). MR significantly increased on exercise with intrinsic rhythm and RV pacing, whereas with LV and BiV pacing, there were no significant exercise-induced increases in any MR variable. There were relationships between changes in measures of dyssynchrony and reductions in MR at rest and during exercise. CONCLUSIONS: CRT reduces MR at rest and during exercise, and prevents exercise-induced MR. Reductions in MR during exercise correlate with improvements in dyssynchrony.