Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest ...carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.
While many studies have examined the barrier effects of large rivers on animal dispersal and gene flow, few studies have considered the barrier effects of small streams. We used displacement ...experiments and analyses of genetic population structure to examine the effects of first-order and second-order streams on the dispersal of terrestrial red-backed salamanders,
Plethodon cinereus
(Green, 1818). We marked red-backed salamanders from near the edges of one first-order stream and one second-order stream, and experimentally displaced them either across the stream or an equal distance farther into the forest. A comparison of return rates indicated that both streams were partial barriers to salamander movement, reducing return rates by approximately 50%. Analysis of six microsatellite loci from paired plots on the same side and on opposite sides of the second-order stream suggested that the stream did contribute to genetic differentiation of salamander populations. Collectively, our results imply that low-order streams do influence patterns of movement and gene flow in red-backed salamanders. We suggest that given the high density of first-order and second-order streams in most landscapes, these features may have important effects on species that, like red-backed salamanders, have limited dispersal and large geographic ranges.
The importance of vertebrates, invertebrates, and pathogens for plant communities has long been recognized, but their absolute and relative importance in early recruitment of multiple coexisting ...tropical plant species has not been quantified. Further, little is known about the relationship of fruit traits to seed mortality due to natural enemies in tropical plants. To investigate the influences of vertebrates, invertebrates, and pathogens on reproduction of seven canopy plant species varying in fruit traits, we quantified reductions in fruit development and seed germination due to vertebrates, invertebrates, and fungal pathogens through experimental removal of these enemies using canopy exclosures, insecticide, and fungicide, respectively. We also measured morphological fruit traits hypothesized to mediate interactions of plants with natural enemies of seeds. Vertebrates, invertebrates, and fungi differentially affected predispersal seed mortality depending on the plant species. Fruit morphology explained some variation among species; species with larger fruit and less physical protection surrounding seeds exhibited greater negative effects of fungi on fruit development and germination and experienced reduced seed survival integrated over fruit development and germination in response to vertebrates. Within species, variation in seed size also contributed to variation in natural enemy effects on seed viability. Further, seedling growth was higher for seeds that developed in vertebrate exclosures for Anacardium excelsum and under the fungicide treatment for Castilla elastica, suggesting that predispersal effects of natural enemies may carry through to the seedling stage. This is the first experimental test of the relative effects of vertebrates, invertebrates, and pathogens on seed survival in the canopy. This study motivates further investigation to determine the generality of our results for plant communities. If there is strong variation in natural enemy attack among species related to differences in fruit morphology, then quantification of fruit traits will aid in predicting the outcomes of interactions between plants and their natural enemies. This is particularly important in tropical forests, where high species diversity makes it logistically impossible to study every plant life history stage of every species.
Roads can fragment animal populations by disrupting movement among formerly continuous habitats. Although models have demonstrated that disrupted movement can contribute to long-term extinction, ...there are few empirical data on the effects of roads on animal movement. We used displacement and homing experiments to determine whether forest roads are barriers to the movement of terrestrial salamanders. We displaced 1471 red-backed salamanders (Plethodon cinereus) across five forest roads and compared return rates to those of salamanders displaced equal distances toward the forest interior. Roads significantly reduced the return rate of salamanders, with a mean reduction of 51%. Steep roadside verges further reduced return rates, particularly for salamanders moving downhill across verges. The permeability of roads to salamander movement did not appear to be related to road surface type. Gravel roads had both the highest and lowest observed permeability with the two paved roads intermediate between these. We conclude that narrow forest roads are partial barriers to salamander movement and that steep roadside verges may exacerbate these effects.
We previously linked Laing-type early-onset autosomal dominant distal myopathy (MPD1) to a 22-cM region of chromosome 14. One candidate gene in the region,
MYH7, which is mutated in cardiomyopathy ...and myosin storage myopathy, codes for the myosin heavy chain of type I skeletal muscle fibers and cardiac ventricles. We have identified five novel heterozygous mutations—Arg1500Pro, Lys1617del, Ala1663Pro, Leu1706Pro, and Lys1729del in exons 32, 34, 35, and 36 of
MYH7—in six families with early-onset distal myopathy. All five mutations are predicted, by
in silico analysis, to locally disrupt the ability of the myosin tail to form the coiled coil, which is its normal structure. These findings demonstrate that heterozygous mutations toward the 3′ end of
MYH7 cause Laing-type early-onset distal myopathy.
MYH7 is the fourth distal-myopathy gene to have been identified.
One of the major effects of deforestation is the creation of numerous edge zones where remaining forest meets nonforest habitat. At this interface, edge effects on forest habitats can include altered ...abiotic conditions, changes in rates of competition and predation, and altered community structure. While the edge effects resulting from clear-cuts and other open habitats are well-studied, little is known about the comparative edge effects of forest roads. We studied the effects of forest roads on the abundance, surface activity, and body condition of red-backed salamanders (Plethodon cinereus) and slimy salamanders (P. glutinosus and P. cylindraceus) in the Southern Appalachians of Virginia. We conducted surveys for salamanders at 21 sites where gravel roads bisected mature forest. These sites were divided into three data sets based on region and year of survey. We also carried out an enclosure experiment to determine whether road edges influenced the surface activity and detectability of red-backed salamanders. We found fewer red-backed salamanders near roads in all three data sets. These edge effects extended <20 m into the forest in two of the three data sets but increased linearly out to 80 m in the data set collected during an unusually dry period. In contrast, slimy salamanders showed no clear responses to forest-road edges and had significantly different responses than those of red-backed salamanders. Within our experimental enclosures, red-backed salamander detectability did not differ between edge and interior habitats, suggesting that the patterns we observed were not simply due to changes in salamander activity patterns. Like red-backed salamander counts, soil moisture and cover object area also tended to decrease near roads. The steepness of the gradient in soil moisture was a significant predictor of the steepness of the decline in salamander counts, while there was no significant relationship between the decreases in cover object area and decreases in salamander counts. Collectively, these results show that edge effects from forest roads may be comparable to edge effects from clear-cuts or other types of silvicultural edges. Additionally, they suggest that, for terrestrial salamanders, variation in the magnitude of edge effects may be related to variation in soil moisture. Management approaches that minimize soil desiccation associated with road building and maintenance may reduce the impacts of roads on amphibian populations in adjacent forest.
Background Although anticoagulation therapy is accepted for most patients with atrial fibrillation, 2 different strategies exist for management of the cardiac rhythm: atrial fibrillation is allowed ...to persist while the ventricular rate is controlled; and atrial fibrillation is converted, and an attempt is made to maintain sinus rhythm. Methods The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) Study was a randomized clinical trial that compared these 2 strategies. We report the baseline characteristics of the patients enrolled in the AFFIRM Study. Results More than 7400 patients at more than 200 North American hospitals and clinics qualified for enrollment in the AFFIRM Study. A total of 4060 patients were enrolled in the AFFIRM Study. The average age of patients enrolled was 70 years, with 39% female and 89% white. Hypertension was present in 71%. Coronary artery disease was present in 38%. Echocardiography was performed in 3311 patients, and results showed normal ventricular function in 68% and normal left atrial size in 33%. Most patients with recurrent episodes had symptoms with atrial fibrillation. Approximately one third of patients were enrolled with a first episode of atrial fibrillation. Conclusion The AFFIRM Study enrolled 4060 predominantly elderly patients with atrial fibrillation to compare ventricular rate control with rhythm control. The patients in the AFFIRM Study were representative of patients at high risk for complications from atrial fibrillation, which indicates that the results of this large clinical trial will be relevant to patient care. (Am Heart J 2002;143:991-1001.)
A filamentous virus identified in coleus (Coleus x hybrida) in Minnesota and New York was found to cause veinal necrosis in coleus, although this symptom was observed only under certain conditions. ...The virus was transmitted readily by mechanical inoculation to coleus and Nicotiana spp. and was not transmitted by Myzus persicae. The particles of the coleus virus had a modal length of 640 nm and a single capsid protein with an estimated molecular mass of 34 kDa. The amino acid sequence of the coat protein region of the coleus virus genome had significant similarities only to the corresponding domain of carlaviruses. Based on virion morphology, capsid protein size, genome size and organization, amino acid sequence, and phylogenetic analyses, the coleus virus, which was named provisionally Coleus vein necrosis virus (CVNV), was concluded to be a new definitive member of the genus Carlavirus. A 2-kb fragment of the 3' terminus of the CVNV genome sequence is accessible under accession number DQ915963 in GenBank.
Table of Contents Preamblee79 Introductione81 Methodology and Evidence Reviewe81 Organization of the GWCe82 Document Review and Approvale82 Scope of the CPGe82 Definitions of Urgency and Riske83 ...Clinical Risk Factorse83 Coronary Artery Diseasee83 Heart Failuree85 Role of HF in Perioperative Cardiac Risk Indicese85 Risk of HF Based on Left Ventricular Ejection Fraction: Preserved Versus Reducede85 Risk of Asymptomatic Left Ventricular Dysfunctione85 Role of Natriuretic Peptides in Perioperative Risk of HFe86 Cardiomyopathye86 Valvular Heart Disease: Recommendationse87 Aortic Stenosis: Recommendatione87 Mitral Stenosis: Recommendatione88 Aortic and Mitral Regurgitation: Recommendationse88 Arrhythmias and Conduction Disorderse88 Cardiovascular Implantable Electronic Devices: Recommendatione89 Pulmonary Vascular Disease: Recommendationse90 Adult Congenital Heart Diseasee90 Calculation of Risk to Predict Perioperative Cardiac Morbiditye90 Multivariate Risk Indices: Recommendationse90 Inclusion of Biomarkers in Multivariable Risk Modelse91 Approach to Perioperative Cardiac Testinge91 Exercise Capacity and Functional Capacitye91 Stepwise Approach to Perioperative Cardiac Assessment: Treatment Algorithme93 Supplemental Preoperative Evaluatione95 The 12-Lead Electrocardiogram: Recommendationse95 Assessment of LV Function: Recommendationse96 Exercise Stress Testing for Myocardial Ischemia and Functional Capacity: Recommendationse97 Cardiopulmonary Exercise Testing: Recommendatione97 Pharmacological Stress Testinge97 Noninvasive Pharmacological Stress Testing Before Noncardiac Surgery: Recommendationse97 Radionuclide MPIe98 Dobutamine Stress Echocardiographye98 Stress Testing--Special Situationse99 Preoperative Coronary Angiography: Recommendatione99 Perioperative Therapye99 Coronary Revascularization Before Noncardiac Surgery: Recommendationse100 Timing of Elective Noncardiac Surgery in Patients With Previous PCI: Recommendationse115 Future Research Directionse116 Referencese117 Appendix 1 Author Relationships With Industry and Other Entities (Relevant)e129 Appendix 2 Reviewer Relationships With Industry and Other Entities (Relevant)e131 Appendix 3 Related Recommendations From Other CPGse136 Appendix 4 Abbreviationse137 Preamble The American College of Cardiology (ACC) and the American Heart Association (AHA) are committed to the prevention and management of cardiovascular diseases through professional education and research for clinicians, providers, and patients. Since 1980, the ACC and AHA have shared a responsibility to translate scientific evidence into clinical practice guidelines (CPGs) with recommendations to standardize and improve cardiovascular health.
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