A Model of Knot Shape and Volume in Loblolly Pine Trees

The shape and structure of branches attached internally to the stem (knots) for loblolly pine (Pinus taeda L.) trees were modeled. Data on knot shape were obtained from the dissection of branches taken from 34 22-yr-old sample trees growing under ten different initial spacings. A total of 341 branches located below the live crown were dissected in the radial/tangential plane. Afterward, a procedure was implemented to reconstruct the branch diameter perpendicular to the branch pith. This information was used to develop a model for representing knot shape, which assumed that the live portion of a knot can be modeled with a one-parameter equation and the dead portion by assuming a cylindrical shape. To study the variability in shape of individual knots (live portion), the model was fitted to 218 branch profiles using nonlinear mixed-effects modeling techniques. A graphical analysis indicated that the random-effects parameter was related to branch diameter. Thus, branch diameter was included as a predictor variable to reduce between-individual variability in knot shape. Reconstructed knots with smaller diameters were more cylindrical; those with larger diameters were more parabolic or conical in shape. Analytical expressions were derived for estimating the volume of knots (live/dead portions) for three types of branch conditions on simulated trees: 1) live branches; 2) nonoccluded dead branches; and 3) occluded dead branches. The knot model assumes a substantial simplification of branch morphology, but should be useful for representing knots as 3-D entities in the stems of loblolly pine trees

Coronary artery aneurysm: case report

<p>Abstract</p> <p>Introduction</p> <p>Aneurysms of the left main coronary artery are rare with an incidence of 0.1% in large angiographic series. The majority are atherosclerotic in origin. Other causes include connective tissue disorders, trauma, vasculitis, congenital, mycotic and idiopathic. The primary complication is myocardial ischemia or infarction, with rupture being rare. Treatment options include anticoagulation, custom made covered stents, reconstruction, resection, and exclusion with bypass.</p> <p>Case Presentation</p> <p>A 66 year-old man was referred for evaluation of a 2 × 2 centimeter saccular aneurysm originating from the distal left main coronary artery. There was associated calcification and mild stenosis of the LM. The workup was prompted by a non-ST elevation myocardial infarction suffered following a laparotomy for a ruptured appendix. The past medical history was pertinent for hypertension, hyperlipidemia, and a left carotid endarterectomy.</p> <p>Cardiopulmonary bypass with hyperkalemic cardioplegic arrest was utilized. The aneurysm was exposed in the atrioventricular groove. The aneurysm was resected and oversewn. Calcification precluded patch angioplasty. The patient then underwent coronary bypass grafting with the left internal thoracic artery placed to the left anterior descending artery and a reversed greater saphenous vein graft to an obtuse marginal branch of the circumflex artery. The postoperative course was uneventful and discharge to home occurred on the fourth postoperative day. Surgical pathology confirmed an atheromatous coronary artery aneurysm.</p> <p>Conclusion</p> <p>Left main coronary artery aneurysms in adult patients are predominantly atherosclerotic in origin. The clinical presentation is that of myocardial ischemia, likely from associated embolism. Rupture is rare. Operative treatment is exclusion and revascularization.</p

Projection Matrix Models : A Suitable Approach for Predicting Sustainable Growth in Uneven-Aged and Mixed Hyrcanian Forests

The Hyrcanian forests of Iran are mainly managed with the single-selection silvicultural technique. Despite significant ecological benefits associated with selection cutting, this type of forest management leads towards more challenging situations where it is difficult to maintain and practice successful forestry than in even-aged systems. Therefore, this study provides relevant management tools in the form of models to estimate low growth levels in Hyrcanian forests. In the present study, estimation of the population growth rate and then the allowable cut rate of these forests using a matrix model have been calculated in the Gorazbon district. For this purpose, the data of 256 permanent sample plots measured during the years between 2003 and 2012, as well as the data recorded about the trees harvested according to the forestry plan, have been used. As a first step, the most frequently occurring tree species were divided into four groups (beech, hornbeam, chestnut-leaved oak, and other species). Compartments of the district were divided into two groups of logged and unlogged compartments. The purpose of this division was to estimate the allowable cut and compare its volume with the volumes of observed and predicted allowable cuts obtained from forestry plans. The results showed that the total operated allowable cut (OAC) in logged compartments was more than the estimated allowable cut (EAC). In unlogged compartments, the total predicted allowable cut (PAC) was more than EAC. A comparison of EAC and OAC showed that hornbeam has been harvested more than its potential. However, chestnut-leaved oak and other species group have depicted opposite trends. Our models provide important advancements for estimating allowable cut that can enhance the goal of practicing sustainable forestry

Teaching in Contemporary Forest Resources Curricula: Applications to Courses in Forest Measurements and Biometrics

Foresters face new and evolving challenges as society reconsiders the balance of its interests between wood production and the provision of ecosystem services in the management of forests. Whatever paths this process may take, sound and broad-based decisions will continue to require accurate and relevant measurements of current forest conditions and projections of future conditions under alternative management programs. Forest measurements and biometrics (FMB) will remain a key component of future forest management and a critical element in the education of future forest managers. As professors who both teach and do research in FMB, we offer teaching goals that we believe will improve FMB education in forestry schools to meet future needs. In the following sections, we outline teaching goals for university-level instruction in forest resources curricula and the roles of FMB in modern forestry. We then identify what we feel are the most critical challenges in teaching and learning FMB and discuss selected strategies to meet teaching objectives for FMB. A fourth section presents an overview of how selected strategies can be integrated into FMB classes, including examples and comments on the role that new technology might play in meeting the above-described challenges. The final section summarizes our main points and provides concluding remarks.This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the Society of American Foresters and can be found at: http://www.safnet.org/publications/jof/index.cfm.Keywords: forest inventory and monitoring, teaching applied statistics, Pacific Northwest, forest analysis, forest pedagog

Simulation-Based Training in Cardiac Surgery

BACKGROUND: Operating room surgical training has significant limitations. This study hypothesized that some skills could be learned efficiently and safely by using simulation with component task training, deliberate practice, progressive complexity, and experienced coaching to produce safer cardiac surgeons. METHODS: Training modules included cardiopulmonary bypass, coronary artery bypass grafting, aortic valve replacement, massive air embolism, acute intraoperative aortic dissection, and sudden deterioration in cardiac function. Using deliberate practice, first-year cardiothoracic surgical residents at eight institutions were trained and evaluated on component tasks for each module and later on full cardiac operations. Evaluations were based on five-point Likert-scale tools indexed by module, session, task items, and repetitions. Statistical analyses relied on generalized linear model estimation and corresponding confidence intervals. RESULTS: The 27 residents who participated demonstrated improvement with practice repetitions resulting in excellent final scores per module (mean ± two SEs): cardiopulmonary bypass, 4.80 ± 0.12; coronary artery bypass grafting, 4.41 ± 0.19; aortic valve replacement, 4.51 ± 0.20; massive air embolism, 0.68 ± 0.14; acute intraoperative aortic dissection, 4.52 ± 0.17; and sudden deterioration in cardiac function, 4.76 ± 0.16. The transient detrimental effect of time away from training was also evident. CONCLUSIONS: Overall performance in component tasks and complete cardiac surgical procedures improved during simulation-based training. Simulation-based training imparts skill sets for management of adverse events and can help produce safer surgeons

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Juvenile-Mature Wood Demarcation in Loblolly Pine Trees

Specific gravity data from loblolly pine (Pinus taeda L.) trees in a region-wide thinning study in southeastern United States were used to determine the age of demarcation between juvenile and mature wood. Segmented modeling, iterative solution, and constrained solution approaches were used to estimate the demarcation age. The results indicated that the age of demarcation between juvenile and mature wood occurs at approximately 11 years of physiological or cambial age (i.e., number of rings from the pith). Constraining the slope of the mature wood equation to a non-negative value lowered the demarcation age typically to less than 10 years. Within-tree variation in the age of demarcation was minor, suggesting that the use of the demarcation age estimate at breast height is adequate when quantifying the proportion of juvenile wood in a tree. Variations in the age of demarcation along the stem due to thinning effects and physiographic region did not show consistent trends. Trees in the Coastal Plain, however, tended to have lower ages of demarcation than trees from other areas

Effects of Early Pruning on Ring Specific Gravity in Young Loblolly Pine Trees

Juvenile wood is not well suited for use in many forest products. Understanding factors that affect the formation of juvenile and mature wood is important when managing commercially important conifer species. The purpose of this investigation was to determine the contribution of ring age, relative height in the stem, and crown position (within or not within the green crown) on ring specific gravity of loblolly pine trees pruned at young ages. A designed experiment consisting of five treatments, control; prune at age 3 yr, age 6 yr, or age 9 yr; and at ages 3,6, and 9 yr, was established at two locations in the Piedmont region of Virginia. Wood samples were acquired at three heights along the stem 15 yr after planting. Results showed that differences in ring specific gravity of the treated plots (Half of green crown removed at each scheduled pruning) were significantly higher than that of the control plots. All variables of ring age, relative height and ring position of within or not within the green crown, were statistically significant. The results suggest that cambial age, maturation, and proximity to green crown are important for controlling whole-ring specific gravity in loblolly pine trees.