Li-O2 Kinetic Overpotentials: Tafel Plots from Experiment and First-Principles Theory.

We report the current dependence of the fundamental kinetic overpotentials for Li-O2 discharge and charge (Tafel plots) that define the optimal cycle efficiency in a Li-air battery. Comparison of the unusual experimental Tafel plots obtained in a bulk electrolysis cell with those obtained by first-principles theory is semiquantitative. The kinetic overpotentials for any practical current density are very small, considerably less than polarization losses due to iR drops from the cell impedance in Li-O2 batteries. If only the kinetic overpotentials were present, then a discharge-charge voltaic cycle efficiency of ∼85% should be possible at ∼10 mA/cm(2) superficial current density in a battery of ∼0.1 m(2) total cathode area. We therefore suggest that minimizing the cell impedance is a more important problem than minimizing the kinetic overpotentials to develop higher current Li-air batteries.

Antimicrobials, drug discovery, and genome mining.

Over the years, antibiotics have provided an effective treatment for a number of microbial diseases. However recently, there has been an increase in resistant microorganisms that have adapted to our current antibiotics. One of the most dangerous pathogens is methicillin-resistant Staphylococcus aureus (MRSA). With the rise in the cases of MRSA and other resistant pathogens such as vancomycin-resistant Staphylococcus aureus, the need for new antibiotics increases every day. Many challenges face the discovery and development of new antibiotics, making it difficult for these new drugs to reach the market, especially since many of the pharmaceutical companies have stopped searching for antibiotics. With the advent of genome sequencing, new antibiotics are being found by the techniques of genome mining, offering hope for the future.

Twin Problems of Interfacial Carbonate Formation in Nonaqueous Li-O2 Batteries.

We use XPS and isotope labeling coupled with differential electrochemical mass spectrometry (DEMS) to show that small amounts of carbonates formed during discharge and charge of Li-O2 cells in ether electrolytes originate from reaction of Li2O2 (or LiO2) both with the electrolyte and with the C cathode. Reaction with the cathode forms approximately a monolayer of Li2CO3 at the C-Li2O2 interface, while reaction with the electrolyte forms approximately a monolayer of carbonate at the Li2O2-electrolyte interface during charge. A simple electrochemical model suggests that the carbonate at the electrolyte-Li2O2 interface is responsible for the large potential increase during charging (and hence indirectly for the poor rechargeability). A theoretical charge-transport model suggests that the carbonate layer at the C-Li2O2 interface causes a 10-100 fold decrease in the exchange current density. These twin "interfacial carbonate problems" are likely general and will ultimately have to be overcome to produce a highly rechargeable Li-air battery.

Limitations in Rechargeability of Li-O2 Batteries and Possible Origins.

Quantitative differential electrochemical mass spectrometry (DEMS) is used to measure the Coulombic efficiency of discharge and charge [(e(-)/O2)dis and (e(-)/O2)chg] and chemical rechargeability (characterized by the O2 recovery efficiency, OER/ORR) for Li-O2 electrochemistry in a variety of nonaqueous electrolytes. We find that none of the electrolytes studied are truly rechargeable, with OER/ORR <90% for all. Our findings emphasize that neither the overpotential for recharge nor capacity fade during cycling are adequate to assess rechargeability. Coulometry has to be coupled to quantitative measurements of the chemistry to measure the rechargeability truly. We show that rechargeability in the various electrolytes is limited both by chemical reaction of Li2O2 with the solvent and by electrochemical oxidation reactions during charging at potentials below the onset of electrolyte oxidation on an inert electrode. Possible mechanisms are suggested for electrolyte decomposition, which taken together, impose stringent conditions on the liquid electrolyte in Li-O2 batteries.

Does the sunset of mental health parity really matter?

The 1996 Mental Health Parity Act (MHPA), which became effective in January 1998, is scheduled to expire in September 2001. This article provides an overview of what the MHPA intended to do and what it actually has accomplished. We summarize state legislature actions through the end of 2000 and report on their effects on employer-sponsored mental health coverage using a national survey fielded in 1999-2000. We then discuss possible amendments to the MHPA and reforms beyond full parity that might be considered.

Toward full mental health parity and beyond.

The 1996 Mental Health Parity Act (MHPA), which became effective in January 1998, is scheduled to expire in September 2001. This paper examines what the MHPA accomplished and steps toward more comprehensive parity. We explain the strategic and self-reinforcing link of parity with managed behavioral health care and conclude that the current path will be difficult to reverse. The paper ends with a discussion of what might be behind the claims that full parity in mental health benefits is insufficient to achieve true equity and whether additional steps beyond full parity appear realistic or even desirable.

The impact of realignment on utilization and cost of community-based mental health services in California.

Decentralization of California's public mental health system under program realignment has changed the utilization and cost of community-based mental health services. This study examined a sample of 75,951 users, representing 1.5 million adults who visited California's public mental health services during a 6-year period (FY 1988-1990 and FY 1992-1994). Regression analysis was performed to examine cost and utilization reduction over time, across regions, and across psychiatric diagnoses. Overall utilization and cost of community-based mental health services dropped significantly after the implementation of realignment. They were significantly lower for (a) 24-hour services in the urban industrialized Southern Region and (b) outpatient services in the agricultural Central Region of the state. Users diagnosed with mood disorders took a greater portion, but were associated with significantly less treatment and cost than other users in the post-realignment period. When local communities bear the financial risks and rewards, they find more efficient methods of delivering community-based mental health services.

The impact of risk shifting and contracting on mental health service costs in California.

This paper identifies the impact of "program realignment," a 1991 California state policy that significantly enhanced local governments' financial risk and programmatic authority for public mental health services, on treatment costs per user, and on the mix of inpatient and outpatient service costs. The study employs a natural pre-realignment and post-realignment design using the 59 California local mental health authorities (LMHAs) as the unit of analysis over a seven-year period spanning policy implementation. Total treatment and inpatient cost per user decreases and outpatient cost per user increases after program realignment. Higher levels of contracting with private providers tend to enhance this trend, while risk for institutional services reduces user costs uniformly. Financial and programmatic decentralization can enhance cost efficiency in treatment, while promoting substitution of outpatient services for inpatient services. Local conditions such as risk and contracting determine the extent of the policy response.

Managed care and fee discounts in psychiatry: new evidence.

This article describes the extent of managed care and fee discounting in psychiatric practice using data on 970 randomly sampled American Psychiatric Association members from the 1996 National Survey of Psychiatric Practice. Seventy percent of psychiatrists were found to have some patients in managed behavioral health care programs. The survey data illustrate that psychiatrists' involvement in managed care spans primary practice settings and is fairly evenly distributed across regions of the United States. Nationally, psychiatrists discount fees for 35% of their patients, with significant variation by practice type and extent of involvement in managed behavioral health care. The average level of discount is 25% with little variation by practice type or extent of involvement in managed behavioral health care. There is little evidence that psychiatrists with patients in managed care have higher fee levels than psychiatrists with no patients in managed care.

An update on Spain's health care system: is it time for managed competition?

Using national data and the most recent OECD figures, we provide an updated assessment of the Spanish health care system and its reforms. We compare figures from Spain with other major industrialized nations and find that the Spanish system appears macro-economically efficient and equitable. However, like many other countries in Europe and elsewhere, the Spanish health care system confronts continued pressures to provide high-quality universal care in the face of ever increasing costs and competing uses for financial resources. These pressures have prompted the enactment of several reforms, which are reviewed. We draw from the American experience with managed care and managed competition to illustrate possible paths for further reform.

Mental health staffing in managed care organizations: a case study.

This paper examines temporal changes in staffing ratios and configuration of mental health providers per 100,000 members within two full-service staff-model health maintenance organizations (HMOs). Overall workforce reductions in all classes of mental health professionals occurred in the two HMOs from 1992 to 1995. Staffing ratios decreased in both HMOs for psychiatrists and psychologists. In one HMO, the ratio of clinical social workers also decreased over this period. Provider ratios from 1995 are benchmarked against state ratios per 100,000 population. Workforce mix for the two HMOs is contrasted with a single-year average for a large managed behavioral health (carve-out) organization. The authors discuss potential implications of the findings for training of several categories of mental health professionals.

Supply dynamics of the mental health workforce: implications for health policy.

The U.S. mental health workforce is varied and flexible. The strong growth in supply of nonphysician mental health professionals, ranging from psychologists to "midlevel" professionals like social workers and nurse specialists, helps to offset the dwindling numbers of medical graduates entering the field of psychiatry. Primary care physicians often see patients who have some form of mental illness, which they are not always trained to recognize and treat. The data on the supply of several specialists--psychiatrists, clinical psychologists, and clinical social workers--indicate that the distribution of mental health professionals varies widely by state. The composition, supply, and distribution of workers in this field also affect the care of vulnerable populations. Broader policy questions, including the lack of parity between mental and physical health insurance coverage and barriers to entry by nonphysician professions, may limit the cost-effective expansion of this diverse and dynamic workforce.

Changing supply and earning patterns of the mental health workforce.

The authors examine recent trends in the supply and earnings of various mental health providers from 1989 to 1995. The makeup of the mental health workforce is fundamentally different now than a decade ago. The number and earnings of psychiatrists have been relatively flat. The number of psychologists increased by 24%, with their earnings rising rapidly in the 1980s, and remaining level since 1990. The number of clinically trained social workers increased by 87% over the same period, and the number of advanced practice nurses certified in mental health specialties almost doubled, with the earnings of these master's-level providers increasing steadily over the period described. These trends are discussed in the context of major changes in the financing and delivery of mental health care.

[Experiences with transverse resections and vertical incisions in treatment of tracheal stenoses and tracheal injuries]. / Erfahrungen mit Querresektionen und Längsspaltungen in der Behandlung von Trachealstenosen und Trachealverletzungen.

BACKGROUND: The treatment of stenoses and traumatic lesions in subglottic and tracheal areas often requires long term follow-up. This study was undertaken to evaluate the efficiency of tracheal resections and vertical dissections with respect to the length and the quality of the treatment. PATIENTS: Thirty-one adult patients underwent tracheal resections. This group includes one patient with an esophagotracheal fistula which was closed after segmental resection. Two cases of traumatic tracheal lesions in the lower third of the trachea in children are also presented. RESULTS: Long-term intubation was the reason of stenosis in 93.5% of the patients. The tracheal stenosis was successfully resected in 87% of the patients without any complications. The healing process was not related to age and sex. The prognosis was influenced negatively by the type and frequency of previous treatments. We detected paresis of the recurrent nerve postoperatively in two patients. CONCLUSIONS: 1. Our experience has shown that tracheal resection is the optimal treatment of stenosis. 2. The transtracheal access in childhood is very suitable for the closure of tracheal lesions located in the lower third of the trachea.

The productivity of physician assistants and nurse practitioners and health work force policy in the era of managed health care.

Managed care is spreading rapidly in the United States and creating incentives for physician practices to find the most efficient combination of health professionals to deliver care to an enrolled population. Given these trends, it is appropriate to reexamine the roles of physician assistants (PAs) and nurse practitioners (NPs) in the health care workforce. This paper briefly reviews the literature on PA and NP productivity, managed care plans' use of PAs and NPs, and the potential impact of PAs and NPs on the size and composition of the future physician workforce. In general, the literature supports the idea that PAs and NPs could have a major impact on the future health care workforce. Studies show significant opportunities for increased physician substitution and even conservative assumptions about physician task delegation imply a large increase in the number of PAs and NPs that can be effectively deployed. However, the current literature has certain limitations that make it difficult to quantify the future impact of PAs and NPs. Among these limitations is the fact that virtually all formal productivity studies were conducted in fee-for-service settings during the 1970s, rather than managed care settings. In addition, the vast majority of PA and NP productivity studies have viewed PAs and NPs as physician substitutes rather than as members of interdisciplinary health care teams, which may become the dominant health care delivery model over the next 10-20 years.

Folic acid fortification of grain: an economic analysis.

OBJECTIVES: The purpose of this study was to compare the economic costs and benefits of fortifying grain with folic acid to prevent neural tube defects. METHODS: A cost-benefit analysis based on the US population, using the human capital approach to estimate the costs associated with preventable neural tube defects, was conducted. RESULTS: Under a range of assumptions about discount rates, baseline folate intake, the effectiveness of folate in preventing neural tube defects, the threshold dose that minimizes risk, and the cost of surveillance, fortification would likely yield a net economic benefit. The best estimate of this benefit is $94 million with low-level (140 micrograms [mcg] per 100 g grain) fortification and $252 million with high-level (350 mcg/100 g) fortification. The benefit-to-cost ratio is estimated at 4.3:1 for low-level and 6.1:1 for high-level fortification. CONCLUSIONS: By averting costly birth defects, folic acid fortification of grain in the United States may yield a substantial economic benefit. We may have underestimated net benefits because of unmeasured costs of neural tube defects and unmeasured benefits of higher folate intake. We may have overestimated net benefits if the cost of neurologic sequelae related to delayed diagnosis of vitamin B12 deficiency exceeds our projection.

The hospital response to Medicare's Prospective Payment System: an econometric model of Blue Cross and Blue Shield plans.

This paper presents an empirical analysis of the impact that resulted from phase-in of Medicare's Prospective Payment System (PPS) on hospital utilization and payments for the Blue Cross and Blue Shield (BCBS) plans. A pooled cross-sectional time series econometric model was specified and estimated using quarterly hospital utilization and payments of the BCBS plans over the period 1980 to 1987. The results indicate that the implementation of PPS was significantly associated with a lower rate of hospital admissions, days and deflated inpatient payments for the BCBS plan members under age 65. A 1% increase in the proportion of hospital days reimbursed under PPS resulted in a .032% decrease in BCBS plan admissions per 1,000 members, a 0.017% decline in days per 1,000 members and a 0.016% decline in deflated inpatient payment per 1,000 members. The reductions in hospital utilization resulted in lower payments by BCBS plans to participating hospitals suggesting a positive spill-over effect of PPS for private insurers. This research underscores the importance of interaction between federal health policy and the private health insurance market.