Negative relationships between species richness and temporal variability are common but weak in natural systems.

Effects of species diversity on population and community stability (or more precisely, the effects of species richness on temporal variability) have been studied for several decades, but there have been no large-scale tests in natural communities of predictions from theory. We used 91 data sets including plants, fish, small mammals, zooplankton, birds, and insects, to examine the relationship between species richness and temporal variability in populations and communities. Seventy-eight of 91 data sets showed a negative relationship between species richness and population variability; 46 of these relationships were statistically significant. Only five of the 13 positive richness-population variability relationships were statistically significant. Similarly, 51 of 91 data sets showed a negative relationship between species richness and community variability; of these, 26 were statistically significant. Seven of the 40 positive richness-community-variability relationships were statistically significant. We were able to test transferability (i.e., the predictive ability of models for sites that are spatially distinct from sites that were used to build the models) for 69 of 91 data sets; 35 and 31 data sets were transferable at the population and community levels, respectively. Only four were positive at the population level, and two at the community level. We conclude that there is compelling evidence of a negative relationship between species richness and temporal variability for about one-half of the ecological communities we examined. However, species richness explained relatively little of the variability in population or community abundances and resulted in small improvements in predictive ability.

Effectiveness of Africa's tropical protected areas for maintaining forest cover.

The effectiveness of parks for forest conservation is widely debated in Africa, where increasing human pressure, insufficient funding, and lack of management capacity frequently place significant demands on forests. Tropical forests house a substantial portion of the world's remaining biodiversity and are heavily affected by anthropogenic activity. We analyzed park effectiveness at the individual (224 parks) and national (23 countries) level across Africa by comparing the extent of forest loss (as a proxy for deforestation) inside parks to matched unprotected control sites. Although significant geographical variation existed among parks, the majority of African parks had significantly less forest loss within their boundaries (e.g., Mahale Park had 34 times less forest loss within its boundary) than control sites. Accessibility was a significant driver of forest loss. Relatively inaccessible areas had a higher probability (odds ratio >1, p < 0.001) of forest loss but only in ineffective parks, and relatively accessible areas had a higher probability of forest loss but only in effective parks. Smaller parks less effectively prevented forest loss inside park boundaries than larger parks (T = -2.32, p < 0.05), and older parks less effectively prevented forest loss inside park boundaries than younger parks (F2,154 = -4.11, p < 0.001). Our analyses, the first individual and national assessment of park effectiveness across Africa, demonstrated the complexity of factors (such as geographical variation, accessibility, and park size and age) influencing the ability of a park to curb forest loss within its boundaries.

Empirical analysis suggests continuous and homogeneous circulation of Newcastle disease virus in a wide range of wild bird species in Africa.

Newcastle disease (ND) is one of the most important poultry diseases worldwide and can lead to annual losses of up to 80% of backyard chickens in Africa. All bird species are considered susceptible to ND virus (NDV) infection but little is known about the role that wild birds play in the epidemiology of the virus. We present a long-term monitoring of 9000 wild birds in four African countries. Overall, 3·06% of the birds were PCR-positive for NDV infection, with prevalence ranging from 0% to 10% depending on the season, the site and the species considered. Our study shows that ND is circulating continuously and homogeneously in a large range of wild bird species. Several genotypes of NDV circulate concurrently in different species and are phylogenetically closely related to strains circulating in local domestic poultry, suggesting that wild birds may play several roles in the epidemiology of different NDV strains in Africa. We recommend that any strategic plan aiming at controlling ND in Africa should take into account the potential role of the local wild bird community in the transmission of the disease.

Understanding the ecological drivers of avian influenza virus infection in wildfowl: a continental-scale study across Africa.

Despite considerable effort for surveillance of wild birds for avian influenza viruses (AIVs), empirical investigations of ecological drivers of AIV prevalence in wild birds are still scarce. Here we used a continental-scale dataset, collected in tropical wetlands of 15 African countries, to test the relative roles of a range of ecological factors on patterns of AIV prevalence in wildfowl. Seasonal and geographical variations in prevalence were positively related to the local density of the wildfowl community and to the wintering period of Eurasian migratory birds in Africa. The predominant influence of wildfowl density with no influence of climatic conditions suggests, in contrast to temperate regions, a predominant role for inter-individual transmission rather than transmission via long-lived virus persisting in the environment. Higher prevalences were found in Anas species than in non-Anas species even when we account for differences in their foraging behaviour (primarily dabbling or not) or their geographical origin (Eurasian or Afro-tropical), suggesting the existence of intrinsic differences between wildfowl taxonomic groups in receptivity to infection. Birds were found infected as often in oropharyngeal as in cloacal samples, but rarely for both types of sample concurrently, indicating that both respiratory and digestive tracts may be important for AIV replication.

Soft systems thinking and social learning for adaptive management.

The success of adaptive management in conservation has been questioned and the objective-based management paradigm on which it is based has been heavily criticized. Soft systems thinking and social-learning theory expose errors in the assumption that complex systems can be dispassionately managed by objective observers and highlight the fact that conservation is a social process in which objectives are contested and learning is context dependent. We used these insights to rethink adaptive management in a way that focuses on the social processes involved in management and decision making. Our approach to adaptive management is based on the following assumptions: action toward a common goal is an emergent property of complex social relationships; the introduction of new knowledge, alternative values, and new ways of understanding the world can become a stimulating force for learning, creativity, and change; learning is contextual and is fundamentally about practice; and defining the goal to be addressed is continuous and in principle never ends. We believe five key activities are crucial to defining the goal that is to be addressed in an adaptive-management context and to determining the objectives that are desirable and feasible to the participants: situate the problem in its social and ecological context; raise awareness about alternative views of a problem and encourage enquiry and deconstruction of frames of reference; undertake collaborative actions; and reflect on learning.

Evaluating the effectiveness of a web-based intervention to promote mental wellbeing in women and partners following miscarriage, using a modified patient preference trial design: an external pilot.

This article describes an external pilot study of a modified 'partially randomised patient preference' trial comparing a web-based intervention (designed to promote mental wellbeing) with standard care post-miscarriage. Assessment comprised an online administration of baseline measures with follow-up at 3 months following registration. Baseline data were obtained from 60 women (and seven partners) post-discharge from one of two Early Pregnancy Assessment Units. 'Intention to treat' versus a 'per protocol' sensitivity analysis showed the effects of introducing a 'preference' option post-randomisation, and highlights the benefits compared with a randomised controlled trial design to enable a robust evaluation of the website in promoting mental wellbeing after miscarriage.

The genetic causes of the sequential occurrence of multiple primary malignancies in a young woman--5 years on.

The finding of three primary gynaecological malignancies in a young woman attending our unit was documented in 2001. We provide an update on this report as new events have prompted further discussion on the role of clinical guidelines in cancer management. The discovery of a genetic predisposition demonstrates the need for multidisciplinary input and heightened awareness in similar cases while the importance of treating each patient as an individual is emphasized.

Improving network approaches to the study of complex social-ecological interdependencies.

Achieving effective, sustainable environmental governance requires a better understanding of the causes and consequences of the complex patterns of interdependencies connecting people and ecosystems within and across scales. Network approaches for conceptualizing and analyzing these interdependencies offer one promising solution. Here, we present two advances we argue are needed to further this area of research: (i) a typology of causal assumptions explicating the causal aims of any given network-centric study of social-ecological interdependencies; (ii) unifying research design considerations that facilitate conceptualizing exactly what is interdependent, through what types of relationships, and in relation to what kinds of environmental problems. The latter builds on the appreciation that many environmental problems draw from a set of core challenges that re-occur across contexts. We demonstrate how these advances combine into a comparative heuristic that facilitates leveraging case-specific findings of social-ecological interdependencies to generalizable, yet context-sensitive, theories based on explicit assumptions of causal relationships.

The emotional burden of miscarriage for women and their partners: trajectories of anxiety and depression over 13 months.

OBJECTIVE: To identify the trajectories of anxiety and depression in women and in their partners over 13 months after miscarriage. DESIGN: A prospective study with follow up at 6 and 13 months after miscarriage. SETTING: Three Scottish Early Pregnancy Assessment Units. SAMPLE: Of the 1443 eligible individuals approached, 686 (48.3%) consented to participate (432 women; 254 men). Complete data were obtained from 273 women and 133 men at baseline, 6, and 13 months. METHODS: On completion of the management of the index miscarriage, eligible and consenting women and men underwent an initial assessment comprising a semi-structured interview and a standardised self-report questionnaire. The latter was readministered at the follow-up assessments. MAIN OUTCOME MEASURES: The hospital anxiety and depression scale (HADS), a reliable and valid measure of general psychopathology for use in nonpsychiatric samples. RESULTS: Compared with depression, anxiety was overall the greater clinical burden. Over the 13-month period, women reported higher levels of anxiety and depression than men. Over time, a significantly greater level of adjustment was reported by women particularly with regards to the resolution of anxiety symptoms. The effect of time on HADS scores in either gender was similar between subgroups of socio-demographic and clinical factors. CONCLUSIONS: These findings verify that early pregnancy loss represents a significant emotional burden for women, and to some extent for men, especially with regards to anxiety. For many, the detrimental effects of miscarriage are enduring and display a complex course of resolution. These findings are discussed in terms of their clinical implications for early identification and management.

Frequent measurement of chronic pain: an electronic diary and empirical findings.

The PIPER (Prompting Intensity of Pain Electronic Recorder) is a compact data-logging device, easily worn by a subject. It emits audible beeps at pre-programmed times, prompting the subject to enter a pain rating by button press. Ratings are stored, for later down-loading. We report two studies suggesting that PIPER pain ratings have good reliability, and good validity assessed against the VAS. In a third study, the PIPER was found practical for use by elderly subjects, and for periods of more than 2 months. In addition, PIPER pain ratings taken 4 times per day were found to have different properties than 4 other measures of chronic pain, suggesting that very frequent measures should be taken if a full understanding of chronic pain is to be obtained.

Maximal exercise capacity of children with heart defects.

Maximal treadmill tests following the Bruce protocol were performed by 830 children with heart defects and the endurance times compared with normal values from 327 children seen in the same clinic because of normal murmurs and from 388 normal children randomly selected and tested in the schools. When values in the normal clinic children were used as the reference, only 21 percent of the patients with heart defects had endurance times below the 10th percentile line. This line was 14 percent higher in the normal school children, and 47 percent of the patient group had values below the 10th percentile when values in the school children were used as the reference. Maximal heart rate in children with heart defects was almost always in the normal range (180 to 210 beats/min) except in patients with cyanosis or severe valve disease and, when encouraged to continue exercising, even these children had a mean maximal heart rate of 175 beats/min. When comparing the exercise capacity of children with heart defects with that of normal children, the source of the normal children is important; body build needs to be considered, as well as physical activity habits. Clinic patients without heart defects probably serve as a better normal control group than children obtained from the school system. Maximal exercise tests do not necessarily distinguish between children with mild or severe heart disease. Only children with lesions causing cyanosis or children with obviously severe disease have consistent reductions in exercise capacity.

Circulation in neonates with intracranial arteriovenous fistula and cardiac failure.

Two newborn infants with severe cardiac failure caused by a large cerebral arteriovenous communication were studied with complete cardiac catheterization, indicator-dilution curves and angiography. In one infant, studied at age 10 hours, a large right to left shunt through the patent ductus was seen with retrograde aortic flow into the left carotid artery. The entire flow in the descending aorta was supplied from the ductus. The second infant, studied at age 5 days, had a 20 percent right to left shunt through the foramen ovale and the ductus was closed. Hypoxia was caused by inadequate oxygenation of pulmonary venous blood, atrial right to left shunting and possibly ductal right to left shunting. The hemodynamic findings in cases of cerebral arteriovenous fistula would seem to depend on the patient's age at the time the studies are carried out and the severity of the lesion. Cardiac output was more than twice the normal value and blood flow through the arteriovenous fistula was probably greater than 4 liters/min per m2.

Cardiac catheterization in infants and children can be an outpatient procedure.

Many cardiac catheterization procedures in infants and children can be performed on an outpatient basis. This has been the practice in a pediatric hospital for 18 years. Over the last 12 years 1,355 of 2,133 catheterization procedures were performed on an outpatient basis. Excluding newborns, 45 percent of infants under 1 year of age having catheterization procedures were studied as outpatients. After age 1 year, 83 percent of the patients were studied as outpatients. Many of the patients admitted to the hospital would have been suitable for outpatient study. There were no significant complications related to the outpatient program. The main advantage would seem to be a reduction in anxiety concerning the test for children and their parents.

Bruce treadmill test in children: normal values in a clinic population.

The Bruce treadmill protocol is suitable for children as young as age 4 years. Maximal endurance time may be used as the sole criterion of exercise capacity, and normal values were established with 327 children having an innocent heart murmur. Mean endurance time in boys increased from 10.4 minutes at age 4 to 5 years, to 14.1 minutes at age 13 to 15 years. Mean endurance time in girls increased from 9.5 minutes at age 4 to 5 years to 12.3 minutes at age 10 to 12 years. Mean maximal heart rate ranged from 193 to 206 beats/min. Age differences in mean maximal and submaximal heart rates were small. There were negative correlations between endurance time and the ratio of weight to height. There were negative correlations between heart rates at treadmill stages 1 to 3 and the endurance times. The correlation coefficient of endurance time with maximal oxygen uptake was 0.88, but for clinical purposes endurance time alone is a satisfactory indicator of exercise performance.

Obstruction of superior vena cava after the Mustard procedure for transposition of the great arteries. Conservative management of chylothorax.

Chylothorax may be produced by superior vena cava (SVC) obstruction, a recognized complication of the Mustard operation for trasposition of the great arteries. The chylothorax may be reduced by keeping the subject in the upright position. Conservative management is an alternative to repeat operation. This syndrome must be recognized, as it can be confused with congestive heart failure. Severe chylothorax may develop insidiously because of progressive SVC obstruction after the immediate postoperative period.

Long-term effects of switching to cigarettes with lower tar and nicotine yields.

On switching to cigarettes with lower tar and nicotine yields, most individuals smoke more intensively, but it is not clear if this effect persists over a long period. Smoking behaviour was monitored in 10 male and 18 female volunteers at five monthly visits, smoking commercially available cigarettes (tar yield greater than 10 mg), then for six more visits at 6-week intervals after switching (mean reduction of 5.9 mg tar and 0.45 mg nicotine). Puffing behaviour was monitored with a flow sensing holder, and measurements were made before and after smoking of plasma cotinine, carboxyhaemglobin and alveolar carbon monoxide. After switching, cotinine levels only fell 40% of that predicted from the fall in nicotine yields, and there were no systematic trends for the rest of the study. Puff volumes rose (reflecting perhaps the reduced draw resistance of the lower yield cigarettes), and remained higher thereafter. The number of puffs per cigarette appeared to rise on switching, but then decreased again. In conclusion, most effects of switching to lower yield cigarettes appeared to persist for at least 36 weeks, suggesting that the strategy of reducing exposure to cigarette smoke by lowering tar and nicotine yields may be of limited value.

Effect of breathing pattern on gas mixing in a model with asymmetrical alveolar ducts.

A model of the pulmonary airways was used to study three single-breath indices of gas mixing, dead space (VD), slope of the alveolar plateau, and alveolar mixing inefficiency (AMI). In the model, discrete elements of airway volume were represented by nodes. Using a finite difference technique the differential equation for simultaneous convection and diffusion was solved for the nodal network. Conducting airways and respiratory bronchioles were modeled symmetrically, but alveolar ducts asymmetrically, permitting interaction between convection and diffusion. VD, alveolar slope, and AMI increased with increasing flow. Similar trends were seen with inspired volume, although slope decreased at high inspired volumes with constant flow. VD was affected most by inspiratory flow and AMI and alveolar slope by expiratory time. VD fell approximately exponentially with time of breath holding. Eight different breathing patterns were compared. They had a small effect on alveolar slope and AMI and a greater effect on VD. The model shows how series and parallel inhomogeneity occur together and interact in asymmetrical systems: the old argument as to which is the more important should be abandoned.

Accurate measurement of N2 volumes during N2 washout requires dynamic adjustment of delay time.

Measurement of respiratory gas composition by a mass spectrometer lags behind the measurement of gas flow. To obtain specific gas volumes (e.g., the N2 volume) by multiplication and integration of concentration and flow, one has to synchronize flow and concentration signals using the delay time (TD) of the gas analyzer. During the N2 washout, however, gas composition changes and causes alterations of TD. This leads to errors of up to 17 and 70% in the measurement of pulmonary volume and series dead space, respectively, in an ideally mixing physical model of the lung. On the basis of Poiseuille's law and exact measurements of the characteristics of the capillary it is possible to adjust the synchronization, which improves the absolute accuracy considerably.

Recognition of abstract and concrete words in a dichotic listening paradigm.

A dichotic listening paradigm was used to examine the hypothesis that whilst concrete nouns can be processed equally well by both right and left hemispheres, the left hemisphere is superior in processing abstract nouns. Although simple main effects of word frequency, ear of presentation, sex of subject and concreteness / abstractness were significant and in the expected directions, further fine-grained analyses using in particular the laterality coefficient showed that only about a third of the subjects showed a clear right ear advantage, and that this was not related to any of the independent variables. There was no evidence supporting differential hemispheric processing of concrete and abstract words and it is suggested that methods of data analysis used in this kind of research need to be carefully examined.

Intracellular and extracellular antioxidant buffering levels in erythrocytes from pregnancy-induced hypertension.

Both intracellular (lysate thiol, lysate glutathione and lysate superoxide dismutase) and extracellular (plasma thiol, plasma glutathione and membrane thiol) antioxidant buffering levels were measured in red blood cells from patients with pregnancy-induced hypertension (PIH). We found the following. (1) The levels of plasma thiol and plasma glutathione in PIH women with proteinuria were markedly lower than that in the normal pregnancy. (2) The concentrations of lysate glutathione and superoxide dismutase in PIH women with proteinuria were significantly decreased compared with that in the normal pregnancy. (3) With the exception of plasma and lysate glutathione, all the tested antioxidant markers were not significantly different between PIH women without proteinuria and normal pregnancy. (4) There was no statistical correlation between antioxidant buffering level and BP in patients with PIH. We concluded that both extracellular and intracellular antioxidant buffering levels were decreased in patients with PIH, especially in those with proteinuria. The reduction of the antioxidant buffering level could account for several important pathophysiological features of PIH, such as the elevation of intracellular calcium, decreased red blood cell deformability and endothelial damage.