Observation of Stark many-body localization without disorder.

Thermalization is a ubiquitous process of statistical physics, in which a physical system reaches an equilibrium state that is defined by a few global properties such as temperature. Even in isolated quantum many-body systems, limited to reversible dynamics, thermalization typically prevails1. However, in these systems, there is another possibility: many-body localization (MBL) can result in preservation of a non-thermal state2,3. While disorder has long been considered an essential ingredient for this phenomenon, recent theoretical work has suggested that a quantum many-body system with a spatially increasing field-but no disorder-can also exhibit MBL4, resulting in 'Stark MBL'5. Here we realize Stark MBL in a trapped-ion quantum simulator and demonstrate its key properties: halting of thermalization and slow propagation of correlations. Tailoring the interactions between ionic spins in an effective field gradient, we directly observe their microscopic equilibration for a variety of initial states, and we apply single-site control to measure correlations between separate regions of the spin chain. Furthermore, by engineering a varying gradient, we create a disorder-free system with coexisting long-lived thermalized and non-thermal regions. The results demonstrate the unexpected generality of MBL, with implications about the fundamental requirements for thermalization and with potential uses in engineering long-lived non-equilibrium quantum matter.

Common latitudinal gradients in functional richness and functional evenness across marine and terrestrial systems.

Functional diversity is an important aspect of biodiversity, but its relationship to species diversity in time and space is poorly understood. Here we compare spatial patterns of functional and taxonomic diversity across marine and terrestrial systems to identify commonalities in their respective ecological and evolutionary drivers. We placed species-level ecological traits into comparable multi-dimensional frameworks for two model systems, marine bivalves and terrestrial birds, and used global species-occurrence data to examine the distribution of functional diversity with latitude and longitude. In both systems, tropical faunas show high total functional richness (FR) but low functional evenness (FE) (i.e. the tropics contain a highly skewed distribution of species among functional groups). Functional groups that persist toward the poles become more uniform in species richness, such that FR declines and FE rises with latitude in both systems. Temperate assemblages are more functionally even than tropical assemblages subsampled to temperate levels of species richness, suggesting that high species richness in the tropics reflects a high degree of ecological specialization within a few functional groups and/or factors that favour high recent speciation or reduced extinction rates in those groups.

Extinction risk in extant marine species integrating palaeontological and biodistributional data.

Extinction risk assessments of marine invertebrate species remain scarce, which hinders effective management of marine biodiversity in the face of anthropogenic impacts. To help close this information gap, in this paper we provide a metric of relative extinction risk that combines palaeontological data, in the form of extinction rates calculated from the fossil record, with two known correlates of risk in the modern day: geographical range size and realized thermal niche. We test the performance of this metric-Palaeontological Extinction Risk In Lineages (PERIL)-using survivorship analyses of Pliocene bivalve faunas from California and New Zealand, and then use it to identify present-day hotspots of extinction vulnerability for extant shallow-marine Bivalvia. Areas of the ocean where concentrations of bivalve species with higher PERIL scores overlap with high levels of climatic or anthropogenic stressors should be considered of most immediate concern for both conservation and management.

A positive relationship between functional redundancy and temperature in Cenozoic marine ecosystems.

The long-term effects of climate change on biodiversity and biogeographic patterns are uncertain. There are known relationships between geographic area and both the number of species and the number of ecological functional groups-termed the species-area relationship and the functional diversity-area relationship, respectively. We show that there is a positive relationship between the number of species in an area, the number of ecological functional groups, and oceanic temperature in the shallow-marine fossil record of New Zealand over a time span of ~40 million years. One implication of this relationship is that functional redundancy increases with temperature. This reveals a long-lived and persistent association between the spatial structuring of biodiversity, the temperature-dependence of functional redundancy, and shallow-marine biodiversity in mid-latitudes.

Observation of a prethermal discrete time crystal.

Extending the framework of statistical physics to the nonequilibrium setting has led to the discovery of previously unidentified phases of matter, often catalyzed by periodic driving. However, preventing the runaway heating that is associated with driving a strongly interacting quantum system remains a challenge in the investigation of these newly discovered phases. In this work, we utilize a trapped-ion quantum simulator to observe the signatures of a nonequilibrium driven phase without disorder-the prethermal discrete time crystal. Here, the heating problem is circumvented not by disorder-induced many-body localization, but rather by high-frequency driving, which leads to an expansive time window where nonequilibrium phases can emerge. Floquet prethermalization is thus presented as a general strategy for creating, stabilizing, and studying intrinsically out-of-equilibrium phases of matter.

Spatial filters of function and phylogeny determine morphological disparity with latitude.

The drivers of latitudinal differences in the phylogenetic and ecological composition of communities are increasingly studied and understood, but still little is known about the factors underlying morphological differences. High-resolution, three-dimensional morphological data collected using computerized micro-tomography (micro-CT) allows comprehensive comparisons of morphological diversity across latitude. Using marine bivalves as a model system, this study combines 3D shape analysis (based on a new semi-automated procedure for placing landmarks and semilandmarks on shell surfaces) with non-shape traits: centroid size, proportion of shell to soft-tissue volume, and magnitude of shell ornamentation. Analyses conducted on the morphology of 95% of all marine bivalve species from two faunas along the Atlantic coast of North America, the tropical Florida Keys and the boreal Gulf of Maine, show that morphological shifts between these two faunas, and in phylogenetic and ecological subgroups shared between them, occur as changes in total variance with a bounded minimum rather than directional shifts. The dispersion of species in shell-shape morphospace is greater in the Gulf of Maine, which also shows a lower variance in ornamentation and size than the Florida Keys, but the faunas do not differ significantly in the ratio of shell to internal volume. Thus, regional differences conform to hypothesized effects of resource seasonality and predation intensity, but not to carbonate saturation or calcification costs. The overall morphological differences between the regional faunas is largely driven by the loss of ecological functional groups and family-level clades at high latitudes, rather than directional shifts in morphology within the shared groups with latitude. Latitudinal differences in morphology thus represent a complex integration of phylogenetic and ecological factors that are best captured in multivariate analyses across several hierarchical levels.

Five-year corneal graft survival. A large, single-center patient cohort.

OBJECTIVE: To determine the survival rates and causes of secondary graft failure in a large, consecutive series of penetrating keratoplasties. DESIGN: All eyes undergoing penetrating keratoplasty at a single center were evaluated for factors relating to penetrating keratoplasty preoperatively, surgically, and postoperatively at 1, 3, 6, 9, 12, 18, and 24 months and then at yearly intervals. Since 1986, data analysis has been prospective. SETTING: A large, private practice, tertiary center for corneal disorders and surgery. PATIENTS: A consecutive series of 1819 penetrating keratoplasties performed from August 1982 through August 1990; 13 eyes with primary graft failure were excluded. MAIN OUTCOME MEASURE: Graft failure and causes of failure. Follow-up ranged from 1 to 96 months, with a mean of 26.6 months. RESULTS: Pseudophakic bullous keratopathy was the most common diagnosis necessitating keratoplasty (38.6%). Secondary failures occurred 111 times (6.1%). The 2- and 5-year survival rates for all grafts in the study were 95% and 91%, respectively. While endothelial failure as a result of immunologic allograft reactions was the most common cause of graft failure (27%), problems with the external surface of the graft caused nearly as many failures (25%). The risk of failure from surface-related problems was highest at 3 months after surgery. There were significantly decreased survival rates for grafts in eyes with regrafts (P < .0001), in eyes left aphakic at keratoplasty (P < .0001), and in eyes with deep stromal vascularization (P < .0001). CONCLUSION: Penetrating keratoplasty is a successful form of transplantation, and survival rates are gradually increasing. The risk of graft failure appears highest within the first year after transplantation.

Choice matters: enrollees' views of their health plans.

Enrollees' views of their health plans and physicians are important measures of the performance of the health care system. The Commonwealth Fund's 1994 survey of 3,000 adults in fee-for-service and managed care organizations documents enrollees' experiences with choosing a plan and satisfaction with that plan. Fee-for-service enrollees were more satisfied with their plan's access to and quality of care; managed care enrollees were more satisfied with their plan's cost, paperwork, and coverage of preventive care. The survey also found a high rate of involuntary plan changing, limited choice of physicians, and low levels of satisfaction among low-income managed care enrollees.

Corneal tissue levels of topically applied ciprofloxacin.

The effectiveness of the fluoroquinolone ciprofloxacin is dependent on stromal drug concentrations which exceed the minimum inhibitory concentration90 (MIC90). The purpose of this study is to compare corneal tissue ciprofloxacin levels in patients exposed to three ciprofloxacin dosing regimens before undergoing penetrating keratoplasty. Thirty-one patients were assigned to one of three treatment groups. Group 1 followed a ciprofloxacin dosing regimen compatible with home use [two drops of 0.3% ciprofloxacin (Ciloxan; Alcon Laboratories, Fort Worth, TX, U.S.A.) every 4 h over a 24-h period]. Groups 2 and 3 followed a more tightly controlled dosing regimen designed for a health-care setting (two drops of Ciloxan applied by a trained professional every 15 min over a 4-h period). In groups 1 and 2, corneal epithelium was left intact, whereas in group 3 corneas were abraded. Corneal tissue samples were surgically obtained. Excised buttons were frozen and Ciloxan concentration determined by high-pressure liquid chromatography. Ciloxan corneal tissue concentrations (mean +/- SD) were 8.82 +/- 8.24 micrograms/g tissue in group 1, 166.20 +/- 336.94 micrograms/g tissue in group 2, and 938.30 +/- 1,081.51 micrograms/g tissue in group 3. Ciloxan penetration can be improved by administering the drug in a controlled setting at 15-min intervals over a 4-h period. Individual Ciloxan concentrations exceeded the MIC90 for most key ocular pathogens despite wide variability in all experimental groups.

Access to medical care for adolescents: results from the 1997 Commonwealth Fund Survey of the Health of Adolescent Girls.

PURPOSE: This study examined the factors associated with access to care among adolescents, including gender, insurance coverage, and having a regular source of health care. METHODS: Analyses were done on the 1997 Commonwealth Fund Survey of the Health of Adolescent Girls, a nationally representative sample of in-school adolescents in 5th through 12th grade. Access to health care, missing needed care, and whether the adolescent had private time with their provider were assessed. Cochran-Mantel-Haenszel chi-square statistics were computed using SUDAAN. RESULTS: Nearly a third of the 6748 adolescents surveyed had missed needed care. The most common reason for missing care was not wanting a parent to know (35%). Girls were more likely than boys to miss care (29% vs. 24%). Most adolescents reported using a source of primary health care (92%); girls were more likely than boys to use a physician's office rather than another site (65% vs. 60%). Eleven percent of adolescents reported having no health insurance. Uninsured adolescents were more likely to have missed needed care (46% vs. 25%) [corrected]. CONCLUSIONS: Certain groups of adolescents have less access to health care. Girls have more emotional barriers, such as not wanting parents to know about care, and embarrassment. Adolescents without health insurance are at high risk for missing care because of financial strain. States, insurers, and advocates can influence policies around confidentiality and insurance coverage to address these issues.

Older women's health: clinical care in the postmenopausal years. A roundtable discussion part 2.

Prevention of late-life disability is an important goal in managing the health care of older women. Hormone replacement therapy and regular exercise can protect against osteoporosis and heart disease. Dietary measures can control weight and prevent diabetes. Adequate calcium and vitamin D intake help protect bones from fractures. Mammography and Pap smears are proven screens for early cancer detection. Depression is not unusual in older women, but it is often masked by physical symptoms. Physicians can help women at risk for caregiver burnout by providing referrals and information on community resources. Use of other health professionals, as well as patient education videos and printed materials, can help physicians provide comprehensive care within the time limits of office practice.

Older women's health: 'taking the pulse' reveals gender gap in medical care.

In the United States, for every 100 men age 65 and older, there are 147 women, a ratio that has social and medical consequences. Five panelists "take the pulse" of older women's health in general and in the offices of primary care physicians in particular. They assess the status of medical education and the need to include older women in research and drug trials, issues of gender bias in health insurance and quality of treatment, ways to improve the use of preventive health services--such as mammography and Pap smears--by older women, and the role of office physicians in identifying and helping victims of domestic violence.

Health insurance: the size and shape of the problem.

Assessment of experiences with health care will continue to be important given the rapid changes in the health care system and retreat from broad national attention on health reform. This paper reports on the findings of the 1993 Kaiser/Commonwealth Survey of Americans and their health insurance. The survey findings highlight the chronic problem of uninsurance as well as concerns among those with insurance, including the worry that benefits will be reduced or become unaffordable. Limited choice of health plans and providers and having to join a managed care plan are further concerns. These findings suggest that many Americans' needs remain unaddressed, but they will have to be considered as the health care system is restructured.

Managed care in three states: experiences of low-income African Americans and Hispanics.

This article examines the experiences of low-income, nonelderly Hispanics, African Americans, and whites in managed care (MC), and compares them to their racial/ethnic counterparts enrolled in fee-for-service (FFS) health plans. Survey findings from Florida, Tennessee, and Texas show that MC and FFS enrollees do not differ substantially on most access and satisfaction measures, with a few notable exceptions. When compared with their FFS counterparts, African-American MC enrollees are twice as likely to report problems in obtaining needed care, and Hispanic MC enrollees are nearly twice as likely to rate the extent to which their providers care about them as "fair" or "poor." In contrast, whites in MC are less likely to be without a regular provider than their FFS counterparts, but report greater dissatisfaction with the extent to which providers care about them.

Bilateral jones fractures in a high school football player.

OBJECTIVE: To present a case of a high school football player with bilateral Jones fractures who was treated both conservatively and with acute intramedullary compression screw fixation. BACKGROUND: Jones fractures tend to heal slowly, have a propensity for reinjury, and a significant number progress to delayed union or nonunion. Because of the time constraints imposed by athletic seasons, there is a need to avoid lengthy periods of immobilization. DIFFERENTIAL DIAGNOSIS: Tuberosity fracture, metatarsal stress fracture. TREATMENT: Treatment options include either conservative care or acute intramedullary compression screw fixation. Jones fractures are difficult to treat and can cause prolonged disability. UNIQUENESS: The athlete was treated conservatively for a delayed union of an old stress fracture. X-rays revealed a sclerotic fracture line with partial union after 6 weeks. The athlete underwent open reduction and internal fixation using an intramedullary screw to obtain compression fixation and a graft to aid healing. Several months later, x-rays showed excellent resolution. One year later, he suffered a similar fracture of the other foot. Because of his history and his desire to return to play, he underwent open reduction and internal fixation using an intramedullary compression screw and was allowed to return to competition by the end of the sixth week postsurgery. CONCLUSIONS: Treatment of Jones fracture should be individualized, based on the athlete's needs, the history and clinical presentation, and the initial radiographic appearance of the injury. The literature indicates that a rapid return to activity can be realized using rigid internal fixation and may be the treatment of choice in athletes.

Living longer, staying well: promoting good health for older women.

Women are living longer than ever. A woman who is 65 today can, on average, expect to live another 19 years to age 84. Despite recognition of the essential role preventive care and healthy habits play in these later years, older women and their physicians often miss opportunities to promote good health. Medicare, which provides basic health insurance coverage for those 65 and older, does include coverage of many preventive services. But cost-sharing for many covered services -- as well as uncovered services such as prescription drugs -- creates financial hardship for many older women, particularly those living on low incomes. This issue brief, based on a new analysis of The Commonwealth Fund 1998 Survey of Women's Health, provides insight into the gaps in preventive care that currently exist and the disparities in access to care found between lower- and higher-income older women. It also suggests steps that can be taken to improve older women's health and quality of life.

Cardiovascular risk factors in women with primary Sjögren's syndrome: United Kingdom primary Sjögren's syndrome registry results.

OBJECTIVE: To determine the prevalence of traditional cardiovascular risk factors using established definitions in a large cohort of clinically well-characterized primary Sjögren's syndrome (SS) patients and to compare them to healthy controls. METHODS: Data on cardiovascular risk factors in primary SS patients and controls were collected prospectively using a standardized pro forma. Cardiovascular risk factors were defined according to established definitions. The prevalence of cardiovascular risk factors in the primary SS group was determined and compared to that in the control group. RESULTS: Primary SS patients had a higher prevalence of hypertension (28­50% versus 15.5­25.6%; P < 0.01) and hypertriglyceridemia (21% versus 9.5%; P = 0.002) than age- and sex-matched healthy controls. Furthermore, a significant percentage (56%) of hypertensive patients expected to be on antihypertensive treatment according to best practice was not receiving it. CONCLUSION: Primary SS patients are more than 2 times more likely to experience hypertension and hypertriglyceridemia than age- and sex-matched healthy controls. Additionally, hypertension is underdiagnosed and suboptimally treated in primary SS.

Assessment of blood clot formation and platelet receptor function ex vivo in patients with primary Sjogren's syndrome.

OBJECTIVES: Primary Sjögren's syndrome (pSS) shares clinical features and pathogenetic mechanisms with systemic lupus erythematosus (SLE). SLE is associated with an increased thromboembolic risk; however, it is unclear whether pSS patients are susceptible to thromboembolic diseases. In this study, we examined ex vivo blood clot formation (clot strength, rates of clot formation and lysis) in pSS using thromboelastography (TEG) and platelet aggregation to common agonists using multiple electrode aggregometry (MEA). We also investigated the relationship between TEG/MEA parameters and clinical/laboratory features of pSS. DESIGN: Case control. SETTING: Secondary care, single centre. PARTICIPANTS: 34 pSS patients, 11 SLE patients and 13 healthy volunteers (all women) entered and completed the study. PRIMARY OUTCOMES: TEG and MEA parameters between three subject groups. SECONDARY OUTCOMES: The relationships between TEG/MEA and clinical/laboratory parameters analysed using bivariate correlation analysis with corrections for multiple testing. RESULTS: All TEG and MEA parameters were similar for the three subject groups. After corrections for multiple testing, interleukin (IL)-1α and Macrophage inflammatory proteins (MIP)-1α remain correlated inversely with clot strength (r=-0.686, p=0.024 and r=-0.730, p=0.012, respectively) and overall coagulability (r=-0.640, p=0.048 and r=-0.648, p=0.048). Stepwise regression analysis revealed that several cytokines such as MIP-1α, IL-17a, IL-1α and Interferon (IFN)-γ may be key predictors of clot strength and overall coagulability in pSS. CONCLUSIONS: Clot kinetics and platelet receptor function are normal in pSS. Several cytokines correlate with clot strength and overall coagulability in pSS.