Choice of biodiversity index drives optimal fire management decisions

Preservation of biodiversity is a central goal of conservation management, yet the conditions that promote persistence may differ for the species in the community. For systems subject to stochastic disturbances such as fire, understanding which management practices promote persistence for all species in a community is complex. Before deciding on the best course of action, an objective must be specified. Yet an overarching goal of species persistence can be specified into a measureable objective many different ways. We investigated four alternative management objectives for maximizing species persistence that use common biodiversity indices: (1) attaining the minimally acceptable mix of successional vegetation states to support species' relative abundances, (2) maximizing the arithmetic mean abundance of species, (3) maximizing the geometric mean abundance of species, and (4) minimizing the average extinction risk of species. We used stochastic dynamic programming to model successional changes in vegetation in the presence of both planned and unplanned fires, and utilize an extensive data set on the occurrence of birds, reptiles, and small mammals in different successional states in semiarid Australia. We investigated the influence the choice of objective function and taxonomic focus has on the optimal fire management recommendations. We also evaluated a recent hazard reduction policy to annually burn a fixed amount of the landscape and compare results to the optimal solution. The optimal management strategy to maximize species persistence over a 100-year period is predominantly to minimize wildfires. This is because the majority of species are more likely to occur in intermediate, and late successional vegetation. However the optimal solution showed sensitivity to the objective and the species included in the analysis. These results highlight the need for careful consideration when specifying an objective to represent overarching conservation goals. Using the extinction risk objective, we show that a policy to annually burn 5% of the landscape could increase the average probability of extinction for the modelled species by 7% over the next 100 years compared to the optimal management scenario.

Species distributions and area relationships

The well-known species-area relationship is one of many scaling laws, or allometries, in ecology and biology that have received much attention over the years. We present a new derivation of this relationship based on Yule׳s theory of evolution of species. Using definitions of mutation rates, our analysis yields species-area exponents that are in close agreement with previously observed values.

Current transport across the pentacene/CVD-grown graphene interface for diode applications

We investigate the electronic transport properties across the pentacene/graphene interface. Current transport across the pentacene/graphene interface is found to be strikingly different from transport across pentacene/HOPG and pentacene/Cu interfaces. At low voltages, diodes using graphene as a bottom electrode display Poole–Frenkel emission, while diodes with HOPG and Cu electrodes are dominated by thermionic emission. At high voltages conduction is dominated by Poole–Frenkel emission for all three junctions. We propose that current across these interfaces can be accurately modeled by a combination of thermionic and Poole–Frenkel emission. Results presented not only suggest that graphene provides low resistive contacts to pentacene where a flat-laying orientation of pentacene and transparent metal electrodes are desired but also provides further understanding of the physics at the organic semiconductor/graphene interface.

Skeletal muscle mitochondrial function is associated with longitudinal growth velocity in children and adolescents

CONTEXT

Periods of rapid growth require an increase in energy use and substrate formation. Mitochondrial function contributes to each of these and therefore may play a role in longitudinal growth.

METHODS

Twenty-nine children and adolescents of ages 8-15 yr were enrolled in a comprehensive longitudinal assessment of glucose homeostasis and mitochondrial function. Fasting laboratory studies and an estimate of mitochondrial function (as assessed by the time to recovery of phosphocreatine (PCr) concentration after submaximal quadriceps extension/flexion exercise using (31)P magnetic resonance spectroscopy) were obtained at baseline and annually for 2 yr.

RESULTS

Data were complete for 23 subjects. Subjects were 11.3 ± 1.9 (sd) yr old at the beginning of the study; 61% were male. Average annualized growth velocity at 1 yr for boys was 7.1 ± 1.5 cm/yr and for girls 6.5 ± 1.7 cm/yr. More rapid recovery of PCr concentration, suggestive of greater skeletal muscle oxidative phosphorylation capacity at baseline, was associated with faster growth velocity in the subsequent year (r(2) = 0.29; P = 0.008). In multivariate modeling, baseline mitochondrial function remained significantly and independently associated with growth (R(2) for model = 0.51; P = 0.05 for effect of phosphocreatine recovery time constant), controlling for age, gender, Tanner stage, body mass index Z-score, and height Z-score.

CONCLUSIONS

We report a novel association between time to recovery of PCr concentration after submaximal exercise and faster annual linear growth in healthy children. Future studies are needed to determine the physiological mechanisms and clinical consequences of this observation.

Skeletal muscle phosphocreatine recovery after submaximal exercise in children and young and middle-aged adults

CONTEXT

Elderly subjects have reduced mitochondrial function. However, it remains unclear whether the decline in mitochondrial function begins earlier in the life span.

OBJECTIVE

The objective of the study was to determine skeletal muscle mitochondrial oxidative phosphorylation by (31)phosphorous-magnetic resonance spectroscopy (MRS) across a variety of age groups.

DESIGN

This was a cross-sectional study of 121 healthy normal-weight and overweight individuals from age 8 to 55 yr.

SETTING

The study was conducted at a single university medical center in Boston, MA.

PARTICIPANTS

Participants included 68 children and 53 adults from the Boston community.

INTERVENTIONS AND MAIN OUTCOME MEASURES

Phosphocreatine (PCr) recovery was evaluated by (31)phosphorous-MRS after submaximal exercise. Subjects were also evaluated with anthropometric measurements, metabolic profiles, and measures of physical activity.

RESULTS

PCr recovery determined by (31)phosphorous-MRS is positively associated with age in univariate analysis in a cohort of individuals aged 8-55 yr (r = +0.55, P < 0.0001). Stratification of subjects into four age groups (prepubertal and early pubertal children, pubertal and postpubertal children < 18 yr, young adults aged 18-39 yr, and middle aged adults aged 40-55 yr) demonstrates prolongation of PCr recovery with increasing age across the four groups (P < 0.0001 by ANOVA). The relationship between PCr recovery and age remains strong when controlling for gender; race; ethnicity; body mass index; measures of physical activity and inactivity; and anthropometric, nutritional, and metabolic parameters (P < 0.004).

CONCLUSIONS

Skeletal muscle PCr recovery measured by (31)phosphorous-MRS is prolonged with age, even in children and young adults.

Multiwall nanotubes can be stronger than single wall nanotubes and implications for nanocomposite design

Molecular dynamics modeling shows that multiwall carbon nanotubes (MWCNTs) with sp;{3} interwall bonding have strengths exceeding those of single-wall carbon nanotubes (SWCNTs) containing the same size initial intrawall defect, and are far less sensitive to defect size. Thus, although processing methods used to increase interwall coupling also create intrawall defects, analyses here show that the strengthening effects and enhanced load transfer compensate for the creation of defects and make MWCNTs with interwall bonding preferable to SWCNTs as mechanical reinforcements in composites. These results are consistent with new experimental data and suggest a new design methodology for CNT-based composites.

Multi-species risk analysis, species evaluation and biodiversity conservation

The multi-species conservation approaches starting from Vane-Wright et al. (1991) search for a biologically valid basis to evaluate biodiversity. Such evaluations can be used to optimize reserve boundaries so reserves contain a high level of biodiversity. However, these optimization procedures do not minimize the future loss of biodiversity. We provide a method that can be used to minimize the loss of biodiversity. The method integrates an evolutionary species evaluation with an ecological multi-species risk analysis to estimate the expected loss of phylogenetic diversity. A minimization of this loss will optimize the preservation of phylogenetic diversity.

Obstetric care and cesarean birth rates: a program to monitor quality of care

OBJECTIVE

To study the quality of obstetric care in relation to rising cesarean rates, a Task Force was formed in New York state by the Department of Health and ACOG District II. The Task Force also included the Organization of Obstetric, Gynecologic, and Neonatal Nurses and the Hospital Association of New York State. The goals were to enhance hospitals' in-house review processes, standardize terminology, and improve the quality of care. A premise of the program was that if quality of care improved, cesarean rates would fall.

METHODS

A Dictionary of Terms was developed to standardize clinical and diagnostic terminology. A two-tiered review process was instituted, using internal and external hospital reviews. A format for in-house review of obstetric care was developed and recommended to hospitals. External reviews were conducted at 24 hospitals during 1989-1990. Review teams, composed of obstetrician-gynecologists and obstetric nurses in active obstetric practice, assessed obstetric facilities, staffing, medical care, and the in-house review process. Contacts continued with the hospitals after site visits to follow up on implementation of recommendations. General recommendations to improve care, based on the overall program experience, were distributed to hospitals and physicians as part of educational efforts to improve quality of care.

RESULTS

The state cesarean rate reversed. Statistics for 1989 and 1990 showed a stronger downward trend in reviewed hospitals than in non-reviewed hospitals. A survey of reviewed hospitals reported a positive response to the review process.

CONCLUSION

A successful quality assurance program can be jointly developed by a state regulatory agency and a medical specialty society.

Illness in hemodialysis patients after exposure to chloramine contaminated dialysate

In September 1987, patients at an outpatient dialysis center were exposed to chloramine contaminated dialysate when the carbon filter in a recently modified water treatment system failed. Forty-one patients required transfusion to treat the resultant hemolytic anemia. Epidemiologic investigation demonstrated that the mortality rate among dialysis center patients increased during the 5 months after chloramine exposure when compared with the 12 months before chloramine exposure, but no deaths could be attributed to the exposure. Chloramine is commonly used as a disinfectant in municipal water supplies, and has previously been reported to cause hemolytic anemia in patients undergoing dialysis. Hemodialysis centers in cities that use chloramine in water supplies must design water treatment systems with adequate means for removing chloramine and must monitor processed water closely to ensure that chloramine contamination does not occur. Dialysis centers that make changes in their water processing systems should evaluate all components of the system before changes are made, and must ensure that after modifications are made, processed water meets the standards set by the Association for Advancement of Medical Instrumentation.

Epidermolysis bullosa and aplasia cutis

Recessive dystrophic epidermolysis bullosa with aplasia cutis occurring in a male infant is described. The association of these two rare conditions is reviewed. Reports of the concurrence of large areas of congenital absence of skin, particularly on the lower limbs, in patients with several different types of epidermolysis bullosa suggest that areas of congenital absence of skin in these patients are an initial manifestation of the bullous disease rather than a distinctive entity.

Inhibition of polyamine synthesis suppresses human lymphocyte proliferation without decreasing cytokine production or interleukin 2 receptor expression

Difluoromethylornithine (DFMO) irreversibly inhibits ornithine decarboxylase (ODC), a crucial enzyme in polyamine synthesis, and impairs mitogen-induced lymphocyte proliferation. To examine the mechanism of action of DFMO, we studied the effect of this ODC inhibitor on lymphokine production and interleukin 2 (IL 2) receptor expression. DFMO decreased thymidine uptake of peripheral blood mononuclear cells stimulated by the mitogens phytohemagglutinin, concanavalin A, phorbol myristate acetate and ionomycin 60-70% compared with untreated cells, and the inhibition could be completely reversed by 10 mM spermidine. DFMO had no effect on IL 1 production by monocytes exposed to silica particles. Concentrations of IL 2 increased 7-fold in DFMO-treated, PHA-stimulated PBMC cultures, compared with untreated cells; whereas IL 2 receptor expression as measured by the anti-Tac monoclonal antibody was not affected by the inhibition of ODC. Mixing experiments using cells cultured with or without DFMO indicated that the inhibition by DFMO was not mediated by suppressor cells. Our results strongly support the concept that polyamines are required for a relatively late event in lymphocyte activation occurring after the interaction of IL 2 and its receptor.

Epidemic septic arthritis caused by Serratia marcescens and associated with a benzalkonium chloride antiseptic

During a 6-week period, 10 patients were admitted to a hospital for treatment of knee or shoulder joint infections due to Serratia species. Isolates from eight patients were identified as Serratia marcescens with identical biochemical characteristics and antibiotic susceptibility patterns. Before the onset of infections, all patients had been treated by two orthopedic surgeons who shared an office. Studies revealed that infections were associated with previous joint injections (P = 4.44 X 10(-5] of methylprednisolone and lidocaine. Environmental cultures revealed that a canister of cotton balls soaked in aqueous benzalkonium chloride and two multiple-dose vials of methylprednisolone previously used by office personnel were contaminated with the epidemic strain of S. marcescens. The canister may have served as a potential reservoir for contamination of sterile solutions and equipment used for joint injections, of skin at the injection site, and of hands of personnel. No further cases occurred after the use of aqueous benzalkonium chloride was discontinued.

Dermatitis from cashew nuts

Between April 4 and May 10, 1982, fifty-four individuals developed a poison ivy-like dermatitis 1 to 8 days after eating imported cashew nuts. The patients had a very pruritic, erythematous, maculopapular eruption that was accentuated in the flexural areas of the body. Three had blistering of the mouth and four had rectal itching. Nineteen volunteers (eleven ill and eight well) were patch-tested with 2.5 micrograms of poison ivy urushiol and an acetone extract of cashew nut shells. Patch testing did not predict illness since positive tests to both materials occurred in those who had been ill as well as in those who had been well. Absence of cashew nut shells from two thirds of the bags probably accounted for the lack of correlation between patch testing and illness. All nine who reacted to the cashew extract also reacted to poison ivy urushiol. The three who were not sensitive to poison ivy had no reaction to cashew extract. Mass spectrometry of the cashew shell extract suggested the presence of cardol , one of the allergens in cashew shell oil.

Survey of resting blood pressure values in clinically normal horses

Resting coccygeal blood pressure values were measured, indirectly, on 296 horses (97 Thoroughbreds, 97 Standardbreds and 102 hacks). Blood pressure was found to vary with the class of horse examined; on average Thoroughbreds had significantly higher values than Standardbreds and hacks, whereas blood pressures of the last two groups were not significantly different. There was no demonstrable effect of sex, height or heart rate on blood pressure, but temperature and age did influence the value recorded. Mean (+/- sd) (n = 296) coccygeal uncorrected values (systolic pressure/diastolic pressure) were 112.1 +/- 16.5/77.3 +/- 14.3 mmHg. Allowing for bladder width to tail girth ratios used in each measurement, actual coccygeal pressures of 122.8 +/- 18.6/71.0 +/- 13.4 mmHg were determined. The latter corresponded to values of 149.4 +/- 19.0/97.6 +/- 14.0 mmHg, when corrected to heart (shoulder) level. Normal limits (defined as within 2.5th and 97.5th percentiles) for all horses, regardless of class, were 80 to 144 mmHg/49 to 105 mmHg for coccygeal uncorrected values and 86 to 159 mmHg/45 to 97 mmHg adjusted for bladder width to tail girth ratio.

Hepatitis A associated with a hardware store water fountain and a contaminated well in Lancaster County, Pennsylvania, 1980

In August-October 1980, a sudden increase occurred in the number of cases of jaundice reported among residents of a rural, agricultural section of Lancaster County, Pennsylvania. Investigation confirmed the cases as hepatitis A and showed that the outbreak was associated with consumption of water from a water fountain in a hardware store and water from the adjacent family home, both of which came from a well contaminated with feces. A total of 49 cases occurred from August 11 to October 21 in store customers, employees, family members, and persons visiting the family residence. Unusual features of the outbreak included an epidemic curve with two peaks, a very high attack rate in susceptibles at highest risk (greater than 90%), a high proportion of cases with jaundice (85%), absence of asymptomatic cases, and a high male to female ratio due to the makeup of the group at risk.

Correct occlusive bladder width for indirect blood pressure measurement in horses

The influence of occlusive bladder width on blood pressure, measured indirectly using a doppler ultrasound technique at the middle coccygeal artery, was studied in 6 anesthetized horses. The relationship was investigated on tails with and without hair, and the optimum bladder width (BW)/tail girth (TG) ratio was determined for systolic pressure (SP) and diastolic pressure (DP), with the data grouped as unclipped tails (TT-1), clipped tails (TT-2), and both unclipped and clipped tails collectively (TTB). The optimum BW/TG ratios for SP and DP were 0.296 and 0.866 for TT-1, 0.376 and 1.156 for TT-2, and 0.339 and 0.983 for TTB, respectively. Despite the differences in optimal BW/TG ratios between TT-1 and TT-2, their regression equations were not significantly (P less than 0.05) different and therefore, data could be considered as TTB. The regression equations for TTB showed that a BW/TG ratio of 0.482 underestimated SP and overestimated DP by approximately 8.8%. In mature Thoroughbreds (mean TG 21.5 cm), this value corresponded to a BW of 10.4 cm. Blood pressure measured directly in the greater metatarsal artery was significantly different from that measured directly in the middle coccygeal artery in individual horses, but when averaged over all horses, there was no significant difference between the 2 sites.

Influence of head height on arterial blood pressure in standing horses

Eighteen horses were used to investigate the influence of head position on arterial blood pressure, measured indirectly at the coccygeal artery. Head height significantly altered systolic pressure, diastolic pressure, pulse pressure, and mean arterial pressure, such that head-lowering decreased and head-raising increased all variables.