Evolved variation in cold tolerance among populations of Eldana saccharina (Lepidoptera: Pyralidae) in South Africa.

Among-population variation in chill-coma onset temperature (CTmin ) is thought to reflect natural selection for local microclimatic conditions. However, few studies have investigated the evolutionary importance of cold tolerance limits in natural populations. Here, using a common-environment approach, we show pronounced variation in CTmin (± 4 °C) across the geographic range of a nonoverwintering crop pest, Eldana saccharina. The outcomes of this study provide two notable results in the context of evolved chill-coma variation: (1) CTmin differs significantly between geographic lines and is significantly positively correlated with local climates, and (2) there is a stable genetic architecture underlying CTmin trait variation, likely representing four key genes. Crosses between the most and least cold-tolerant geographic lines confirmed a genetic component to CTmin trait variation. Slower developmental time in the most cold-tolerant population suggests that local adaptation involves fitness costs; however, it confers fitness benefits in that environment. A significant reduction in phenotypic plasticity in the laboratory population suggests that plasticity of this trait is costly to maintain but also likely necessary for field survival. These results are significant for understanding field population adaption to novel environments, whereas further work is needed to dissect the underlying mechanism and gene(s) responsible.

A comprehensive assessment of geographic variation in heat tolerance and hardening capacity in populations of Drosophila melanogaster from eastern Australia.

We examined latitudinal variation in adult and larval heat tolerance in Drosophila melanogaster from eastern Australia. Adults were assessed using static and ramping assays. Basal and hardened static heat knockdown time showed significant linear clines; heat tolerance increased towards the tropics, particularly for hardened flies, suggesting that tropical populations have a greater hardening response. A similar pattern was evident for ramping heat knockdown time at 0.06°C min(-1) increase. There was no cline for ramping heat knockdown temperature (CT(max) ) at 0.1°C min(-1) increase. Acute (static) heat knockdown temperature increased towards temperate latitudes, probably reflecting a greater capacity of temperate flies to withstand sudden temperature increases during summer in temperate Australia. Larval viability showed a quadratic association with latitude under heat stress. Thus, patterns of heat resistance depend on assay methods. Genetic correlations in thermotolerance across life stages and evolutionary potential for critical thermal limits should be the focus of future studies.

A review of irradiated fuel particle releases from the Windscale Piles, 1950-1957.

Radiological assessments have assumed that the mass of irradiated uranium oxide particles inadvertently released to the atmosphere from the Windscale Piles, two nuclear reactors at Windscale Works, Sellafield, England, during the 1950s was 20 kg. This paper re-examines the assumptions upon which this figure was based and concludes that the value is a realistically conservative estimate of the release, consistent with current radiological protection practice. The mass estimate is derived from a reanalysis of plant data produced at the time. The environmental data on which the initial estimates were based are reconfirmed, and additional support is provided by an interpretation of modelling studies of both the total deposition and milk concentrations resulting from that deposition. Milk-monitoring data from the time are shown to be consistent with the release assumptions used in the dispersion modelling exercise. Finally, the issue of statistical undersampling is addressed using the particle numbers and size distributions produced by the modelling exercise.

A methodology for investigating new nonprecious metal catalysts for PEM fuel cells.

This paper reports an approach to investigate metal-chalcogen materials as catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells. The methodology is illustrated with reference to Co-Se thin films prepared by magnetron sputtering onto a glassy-carbon substrate. Scanning Auger microscopy (SAM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) have been used, in parallel with electrochemical activity and stability measurements, to assess how the electrochemical performance relates to chemical composition. It is shown that Co-Se thin films with varying Se are active for oxygen reduction, although the open circuit potential (OCP) is lower than for Pt. A kinetically controlled process is observed in the potential range 0.5-0.7 V (vs reversible hydrogen electrode) for the thin-film catalysts studied. An initial exposure of the thin-film samples to an acid environment served as a pretreatment, which modified surface composition prior to activity measurements with the rotating disk electrode (RDE) method. Based on the SAM characterization before and after electrochemical tests, all surfaces demonstrating activity are dominated by chalcogen. XRD shows that the thin films have nanocrystalline character that is based on a Co(1-x)Se phase. Parallel studies on Co-Se powder supported on XC72R carbon show comparable OCP, Tafel region, and structural phase as for the thin-film model catalysts. A comparison for ORR activity has also been made between this Co-Se powder and a commercial Pt catalyst.

Chaos-induced pulse trains in the ionization of hydrogen.

We predict that a hydrogen atom in parallel electric and magnetic fields, excited by a short laser pulse to an energy above the classical saddle, ionizes via a train of electron pulses. These pulses are a consequence of classical chaos induced by the magnetic field. We connect the structure of this pulse train (e.g., pulse size and spacing) to fractal structure in the classical dynamics. This structure displays a weak self-similarity, which we call "epistrophic self-similarity." We demonstrate how this self-similarity is reflected in the pulse train.

Geometry and topology of escape. I. Epistrophes.

We consider a dynamical system given by an area-preserving map on a two-dimensional phase plane and consider a one-dimensional line of initial conditions within this plane. We record the number of iterates it takes a trajectory to escape from a bounded region of the plane as a function along the line of initial conditions, forming an "escape-time plot." For a chaotic system, this plot is in general not a smooth function, but rather has many singularities at which the escape time is infinite; these singularities form a complicated fractal set. In this article we prove the existence of regular repeated sequences, called "epistrophes," which occur at all levels of resolution within the escape-time plot. (The word "epistrophe" comes from rhetoric and means "a repeated ending following a variable beginning.") The epistrophes give the escape-time plot a certain self-similarity, called "epistrophic" self-similarity, which need not imply either strict or asymptotic self-similarity.

Geometry and topology of escape. II. Homotopic lobe dynamics.

We continue our study of the fractal structure of escape-time plots for chaotic maps. In the preceding paper, we showed that the escape-time plot contains regular sequences of successive escape segments, called epistrophes, which converge geometrically upon each end point of every escape segment. In the present paper, we use topological techniques to: (1) show that there exists a minimal required set of escape segments within the escape-time plot; (2) develop an algorithm which computes this minimal set; (3) show that the minimal set eventually displays a recursive structure governed by an "Epistrophe Start Rule:" a new epistrophe is spawned Delta=D+1 iterates after the segment to which it converges, where D is the minimum delay time of the complex.

A longitudinal study of former trauma center patients: the association between toxicology status and subsequent injury mortality.

BACKGROUND: Despite the current emphasis on injury prevention, little has been done to incorporate alcohol intervention programs into the care of the injured patient. The purpose of this study was to determine whether patients admitted to a trauma center with positive toxicology findings (TOX+) have a higher subsequent injury mortality than those without such findings (TOX-). METHODS: We followed a cohort of 27,399 trauma patients discharged alive between 1983 and 1995 to determine subsequent mortality. Death certificates were obtained to identify the cause of death. RESULTS: TOX+ patients had an injury mortality rate approximately twice that of the TOX- group (1.9% vs. 1.0%, p < 0.001). Overall, 22.7% of the deaths were due to injury; the TOX+ rate was 34.7% versus 15.4% for the TOX-. CONCLUSION: These data add strength to the premise that untreated substance abuse-related injury remains an untapped injury prevention opportunity.

Epidemic increases in cocaine and opiate use by trauma center patients: documentation with a large clinical toxicology database.

BACKGROUND: Although reports have documented alcohol and other drug use by trauma patients, no studies of long-term trends have been published. We assessed substance use trends in a large cohort of patients admitted to a regional Level I adult trauma center between July 1984 and June 2000. METHODS: Positive toxicology results, collected via retrospective database review, were analyzed for patients admitted directly to the center. Data were abstracted from a clinical toxicology database for 53,338 patients. Results were analyzed for alcohol, cocaine, and opiates relative to sex, age (< 40/> or = 40 years), and injury type (nonviolence/violence). Positive toxicology test result trends were assessed for the 3 years at the beginning and end of the period (chi2). Testing biases were assessed for sex, race, and injury type. RESULTS: The patient profile was as follows: men, 72%; age < 40 years, 69%; nonviolence victims, 77%. Alcohol-positive results decreased 37%, but cocaine-positive and opiate-positive results increased 212% and 543%, respectively (all p < 0.001). Cocaine-positive/opiate-positive results increased 152%/640% for nonviolence and 226%/258% for violence victims, respectively (all p < 0.001). In fiscal year 2000, cocaine-positive and opiate-positive results were highest among violence victims (27.4% for both drugs). Cocaine-positive and opiate-positive results among nonviolence victims were 9.4% and 17.6%, respectively. Patients who were minorities or victims of violence were not tested more frequently than other patients. CONCLUSION: Epidemic increases in cocaine and opiate use were documented in all groups of trauma patients, with the greatest increases being in violence victims. Alcohol use decreased for all groups.

Flavonoid characters contributing to the taxonomic revision of the Hebe parviflora complex.

Comparative flavonoid chemistry is a key element of a multidisciplinary study aimed at a revision of the genus Hebe, New Zealand's largest genus of flowering plants. One aspect of this study has been an investigation of the Hebe parviflora complex. A recent botanical paper on this topic marshalls generalised flavonoid data and morphological characters to support the recognition of two species in this complex, Hebe stenophylla and Hebe parviflora, which are clearly distinguishable from each other and from the related Hebe traversii and Hebe strictissima. A detailed study of the flavonoid chemistry and the distributional data used to support these conclusions are presented here. Six new compounds have been isolated in this study, including 6-hydroxyapigenin-7-O-beta-[2-O-beta-xyloxyloside] and-7-O-beta-[2-O-beta-xyloglucoside], 6-hydroxyluteolin-7-O-beta-[2-O-beta-xyloxyloside] and, luteolin-, 6-hydroxyluteolin- and 4'-O-methylluteolin-7-O-beta-[6-O-beta-xyloglucoside]. Other flavonoids include apigenin and luteolin 7- and 4'- mono-, di- and possibly tri-O-glycosides, 8-hydroxyluteolin 7- and 8-O-glucosides, and kaempferol and quercetin 3-O-mono- and di-glycosides. New structure assignments are supported with detailed 1H and 13C NMR data, including HMQC and HMBC measurements.

Anthocyanic vacuolar inclusions--their nature and significance in flower colouration.

The petals of a number of flowers are shown to contain similar intensely coloured intravacuolar bodies referred to herein as anthocyanic vacuolar inclusions (AVIs). The AVIs in a blue-grey carnation and in purple lisianthus have been studied in detail. AVIs occur predominantly in the adaxial epidermal cells and their presence is shown to have a major influence on flower colour by enhancing both intensity and blueness. The latter effect is especially dramatic in the carnation where the normally pink pelargonidin pigments produce a blue-grey colouration. In lisianthus, the presence of large AVIs produces marked colour intensification in the inner zone of the petal by concentrating anthocyanins above levels that would be possible in vacuolar solution. Electron microscopy studies on lisianthus epidermal tissue failed to detect a membrane boundary in AVI bodies. AVIs isolated from lisianthus cells are shown to have a protein matrix. Bound to this matrix are four cyanidin and delphinidin acylated 3,5-diglycosides (three, new to lisianthus), which are relatively minor anthocyanins in whole petal extracts where acylated delphinidin triglycosides predominate. Flavonol glycosides were not bound. A high level of anthocyanin structural specificity in this association is thus implied. The specificity and effectiveness of this anthocyanin "trapping" is confirmed by the presence in the surrounding vacuolar solution of only delphinidin triglycosides, accompanied by the full range of flavonol glycosides. "Trapped" anthocyanins are shown to differ from solution anthocyanins only in that they lack a terminal rhamnose on the 3-linked galactose. The results of this study define for the first time the substantial effect AVIs have on flower colour, and provide insights into their nature and their specificity as vacuolar anthocyanin traps.

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suppresses the humoral and cell-mediated immune responses to influenza A virus without affecting cytolytic activity in the lung.

The immune response to influenza virus is exquisitely sensitive to suppression by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); however, the cellular mechanisms underlying the suppressive effects of TCDD are unknown. Mice exposed to TCDD exhibited a dose-responsive increase in mortality following an otherwise non-lethal influenza virus infection. Given that cytotoxic T lymphocytes (CTL) are generally thought to resolve primary infections in the lung, we tested the hypothesis that exposure to TCDD suppresses T-cell responsiveness, leading to decreased CTL in the lung. After infection with influenza virus, naive CD8+ lymphocytes are activated and differentiate in the mediastinal lymph node (MLN). In mice exposed to TCDD and infected with influenza virus, the number of CD8+ MLN cells was reduced 60% compared to vehicle-treated mice. Moreover, MLN cells from TCDD-treated mice failed to develop cytolytic activity, and the production of interleukin (IL)-2 and interferon (IFN)-gamma was suppressed. Exposure to TCDD also altered the production of virus-specific antibodies, decreased the recruitment of CD8+ cells to the lung, reduced the percentage and number of bronchoalveolar lavage cells bearing a CTL phenotype (CD8+CD44hiCD62L(l) degrees ), and suppressed IL-12 levels in the lung. Despite our findings that exposure to TCDD suppressed T cell-dependent functions, the cytolytic activity of lung lavage cells from TCDD and vehicle treated mice was equivalent, and IFN gamma levels in the lungs of mice treated with TCDD were enhanced 10-fold. Thus, while exposure to TCDD suppressed a number of responses associated with the development of adaptive immunity to influenza virus, a direct link between these effects and enhanced susceptibility to influenza remains unclear.

External fixation as a bridge to intramedullary nailing for patients with multiple injuries and with femur fractures: damage control orthopedics.

BACKGROUND: The advantages of early fracture fixation in patients with multiple injuries have been challenged recently, particularly in patients with head injury. External fixation (EF) has been used to stabilize pelvic fractures after multiple injury. It potentially offers similar benefits to intramedullary nail (IMN) in long-bone fractures and may obviate some of the risks. We report on the use of EF as a temporary fracture fixation in a group of patients with multiple injuries and with femoral shaft fractures. METHODS: Retrospective review of charts and registry data of patients admitted to our Level 1 trauma center July of 1995 to June of 1998. Forty-three patients initially treated with EF of the femur were compared to 284 patients treated with primary IMN of the femur. RESULTS: Patients treated with EF had more severe injuries with significantly higher Injury Severity Scores (26.8 vs. 16.8) and required significantly more fluid (11.9 vs. 6.2 liters) and blood (1.5 vs. 1.0 liters) in the initial 24 hours. Glasgow Coma Scale score was lower (p < 0.01) in those treated with EF (11 vs. 14.2). Twelve patients (28%) had head injuries severe enough to require intracranial pressure monitoring. All 12 required therapy for intracranial pressure control with mannitol (100%), barbiturates (75%), and/or hyperventilation (75%). Most patients had more than one contraindication to IMN, including head injury in 46% of cases, hemodynamic instability in 65%, thoracoabdominal injuries in 51%, and/or other serious injuries in 46%, most often multiple orthopedic injuries. Median operating room time for EF was 35 minutes with estimated blood loss of 90 mL. IMN was performed in 35 of 43 patients at a mean of 4.8 days after EF. Median operating room time for IMN was 135 minutes with an estimated blood loss of 400 mL. One patient died before IMN. One other patient with a mangled extremity was treated with amputation after EF. There was one complication of EF, i.e., bleeding around a pin site, which was self-limited. Four patients in the EF group died, three from head injuries and one from acute organ failure. No death was secondary to the fracture treatment selected. One patient who had EF followed by IMN had bone infection and another had acute hardware failure. CONCLUSION: EF is a viable alternative to attain temporary rigid stabilization in patients with multiple injuries. It is rapid, causes negligible blood loss, and can be followed by IMN when the patient is stabilized. There were minimal orthopedic complications.

Early fracture fixation may be "just fine" after head injury: no difference in central nervous system outcomes.

BACKGROUND: Recent reports suggest that early fracture fixation worsens central nervous system (CNS) outcomes. We compared discharge Glasgow Coma Scale (GCS) scores, CNS complications, and mortality of severely injured adults with head injuries and pelvic/lower extremity fractures treated with early versus delayed fixation. METHODS: Using trauma registry data, records meeting preselected inclusion criteria from the years 1991 to 1995 were examined. We identified 171 patients aged 14 to 65 years (mean age, 32.7 years) with head injuries and fractures who underwent early fixation (< or = 24 hours after admission) (n = 147) versus delayed fixation (> 24 hours after admission) (n = 24). RESULTS: Patients were severely injured, with a mean admission GCS score of 9.1, Revised Trauma Score of 6.2, Injury Severity Score of 38, median intensive care unit length of stay of 16.5 days, and hospital length of stay of 23 days. No differences between groups were found by age, admission GCS score, Injury Severity Score, Revised Trauma Score, intensive care unit length of stay, hospital length of stay, shock, vasopressors, major nonorthopedic operative procedures, total intravenous fluids or blood products, or mortality rates. In survivors, no differences in discharge GCS scores or CNS complications were found. CONCLUSION: We found no evidence to suggest that early fracture fixation negatively influences CNS outcomes or mortality.

Mortality in patients with bilateral femoral fractures.

OBJECTIVES: To determine and compare the mortality rates of patients with bilateral versus unilateral femoral fractures and to determine the contribution of the femoral fracture to, and identify risk factors for, such mortality. STUDY DESIGN: Retrospective analysis using trauma registry data on consecutive blunt trauma patients with unilateral (800 patients, group I) or bilateral (eighty-five patients, group II) femoral fractures. METHODS: Univariate data analysis was performed to compare the groups' ages, Injury Severity Scores, Glasgow Coma Scale values, mortality, and the presence of adult respiratory distress syndrome (ARDS). Logistic regression analysis was performed to determine variables statistically associated with mortality. RESULTS: Group II patients had a significantly higher Injury Severity Score (30.2 versus 24.5, p < 0.001), lower Glasgow Coma Scale value (12.3 versus 13.1, p = 0.05), higher mortality rate (25.9 vs 11.7%, p < 0.001), and higher incidence of ARDS (15.7 versus 7.27%, p = 0.014) than group I patients. Group II patients also had significantly more closed head injuries, open skull fractures, intraabdominal injuries requiring surgical intervention, and pelvic fractures; the rates of thoracic injury were similar. Regression analysis of variables evident on admission revealed a significant correlation between bilateral femoral fractures and death; however, other factors (shock, closed head injury, and thoracic injury) had much stronger correlations with mortality. CONCLUSIONS: Patients with bilateral femoral fractures have a significantly higher risk of death, ARDS, and associated injuries than patients with unilateral femoral fractures. This increase in mortality is more closely related to associated injuries and physiologic parameters than to the presence of bilateral femoral fractures. The presence of bilateral femoral fractures should alert the clinician to the likelihood of associated injuries, a higher Injury Severity Score, and the potential for a more serious prognosis.

Partners in nursing education.

In this article, the authors present the efforts of several hospitals in a large southern city to collaborate on continuing education projects to meet the needs of the nursing staff. In 1985, four hospitals formed a health maintenance organization. An outgrowth was the formation of a critical care consortium whose main objective was to develop an entry level critical care course. The authors discuss the development of this course, the advantages and disadvantages of a partnership, and the results of 7 years of experience.

Evaluation of minor head injury in children.

The authors' goal was to determine criteria for hospitalization for children with minor head injuries. A retrospective review was performed of the hospital records of 401 children with isolated minor head injuries who were admitted to a level I pediatric trauma center between July 1988 and December 1990. Specific information regarding each patient was documented, including demographic data, pertinent physical findings, diagnostic studies, criteria for admission, and hospitalization costs. Fifty-one patients with a mechanism of injury compatible with minor head injury, a brief or no loss of consciousness, a Glasgow coma score of 15, and no abnormalities on radiographic examination did not have neurological complications. The authors believe that these 51 patients could have been discharged from the hospital to responsible parents, thereby decreasing the costs of hospitalization. Prospective studies to substantiate these data and determine which patients should be hospitalized are warranted.

Flail chest as a marker for significant injuries.

The records of 92 patients with flail chest injury treated at a Level I trauma center were analyzed retrospectively. Associated intrathoracic injuries included pulmonary contusion (46 percent) and pneumothorax or hemothorax, or both (70 percent). The incidence of great vessel, tracheobronchial and diaphragmatic injuries was no different from that of a control population with simple rib fractures. Adult respiratory distress syndrome developed in 27 percent of patients with flail chest; 69 percent of all patients required ventilation (mean duration, 22 days). Mean length of hospital stay was 24 days. The mortality rate was 33 percent. We conclude that flail chest serves as a marker of significant intrathoracic injury, highly associated with pulmonary contusion, but even more so with pneumothorax or hemothorax. Flail chest does not seem to be a marker for great vessel, tracheobronchial, or diaphragmatic injuries. The majority of patients (more than two-thirds) will require mechanical ventilation for prolonged periods. Of paramount importance is the recognition of flail chest as a marker of high kinetic energy absorption, resulting in life-threatening thoracic as well as nonthoracic injuries.