Critical evaluation of diameter increment modelling in the Great Lakes region

Simulations of forest stand dynamics in a modelling framework including Forest Vegetation Simulator (FVS) are diameter driven, thus the diameter or basal area increment model needs a special attention. This dissertation critically evaluates diameter or basal area increment models and modelling approaches in the context of the Great Lakes region of the United States and Canada. A set of related studies are presented that critically evaluate the sub-model for change in individual tree basal diameter used in the Forest Vegetation Simulator (FVS), a dominant forestry model in the Great Lakes region. Various historical implementations of the STEMS (Stand and Tree Evaluation and Modeling System) family of diameter increment models, including the current public release of the Lake States variant of FVS (LS-FVS), were tested for the 30 most common tree species using data from the Michigan Forest Inventory and Analysis (FIA) program. The results showed that current public release of the LS-FVS diameter increment model over-predicts 10-year diameter increment by 17% on average. Also the study affirms that a simple adjustment factor as a function of a single predictor, dbh (diameter at breast height) used in the past versions, provides an inadequate correction of model prediction bias. In order to re-engineer the basal diameter increment model, the historical, conceptual and philosophical differences among the individual tree increment model families and their modelling approaches were analyzed and discussed. Two underlying conceptual approaches toward diameter or basal area increment modelling have been often used: the potential-modifier (POTMOD) and composite (COMP) approaches, which are exemplified by the STEMS/TWIGS and Prognosis models, respectively. It is argued that both approaches essentially use a similar base function and neither is conceptually different from a biological perspective, even though they look different in their model forms. No matter what modelling approach is used, the base function is the foundation of an increment model. Two base functions – gamma and Box-Lucas – were identified as candidate base functions for forestry applications. The results of a comparative analysis of empirical fits showed that quality of fit is essentially similar, and both are sufficiently detailed and flexible for forestry applications. The choice of either base function in order to model diameter or basal area increment is dependent upon personal preference; however, the gamma base function may be preferred over the Box-Lucas, as it fits the periodic increment data in both a linear and nonlinear composite model form. Finally, the utility of site index as a predictor variable has been criticized, as it has been widely used in models for complex, mixed species forest stands though not well suited for this purpose. An alternative to site index in an increment model was explored, using site index and a combination of climate variables and Forest Ecosystem Classification (FEC) ecosites and data from the Province of Ontario, Canada. The results showed that a combination of climate and FEC ecosites variables can replace site index in the diameter increment model.

Pipes in Steel Ingots as Exemplified by Casting Wax

This paper presents some experimental data on the size and position of pipes steel ingots as exemp1ified by casting wax under various conditions and noting the size and location of the pipes formed. The results tend to show that the length of the pipe is decreased by: 1. Slow casting 2. By casting large end up instead of down 3. By retarding the cooling of the top

Are Warnings on Plastic Films Adequate?

Warnings are used to inform users of hazards that may be associated with many products. Often these warnings deal with the operation of tools, appliances, and other items for which the user may have some reason at least, to look for information on the product regarding its use. Plastic film presents a serious hazard to young children. Because the film will adhere to the flesh, if it covers the airways for the child, suffocation may result. Because young children may play with them, it is important that such films be kept away from them. Warnings need to be adequate to inform or remind caregivers of this fact. This study examined warnings found on various items in commerce and some alternatives to those warnings. The results showed some warnings to be poor at best. The alternative most preferred included both the prohibition sign and a symbolic indication of proper disposal.

The STEREO/PLASTIC response to solar wind ions (Flight measurements and models)

The Plasma and Supra-Thermal Ion Composition (PLASTIC) instrument is one of four experiment packages on board of the two identical STEREO spacecraft A and B, which were successfully launched from Cape Canaveral on 26 October 2006. During the two years of the nominal STEREO mission, PLASTIC is providing us with the plasma characteristics of protons, alpha particles, and heavy ions. PLASTIC will also provide key diagnostic measurements in the form of the mass and charge state composition of heavy ions. Three measurements (E/qk, time of flight, ESSD) from the pulse height raw data are used to characterize the solar wind ions from the solar wind sector, and part of the suprathermal particles from the wide-angle partition with respect to mass, atomic number and charge state. In this paper, we present a new method for flight data analysis based on simulations of the PLASTIC response to solar wind ions. We present the response of the entrance system / energy analyzer in an analytical form. Based on stopping power theory, we use an analytical expression for the energy loss of the ions when they pass through a thin carbon foil. This allows us to model analytically the response of the time of flight mass spectrometer to solar wind ions. Thus we present a new version of the analytical response of the solid state detectors to solar wind ions. Various important parameters needed for our models were derived, based on calibration data and on the first flight measurements obtained from STEREO-A. We used information from each measured event that is registered in full resolution in the Pulse Height Analysis words and we derived a new algorithm for the analysis of both existing and future data sets of a similar nature which was tested and works well. This algorithm allows us to obtain, for each measured event, the mass, atomic number and charge state in the correct physical units. Finally, an important criterion was developed for filtering our Fe raw flight data set from the pulse height data without discriminating charge states.

Soft and hard tissue histologic dimensions around dental implants in the canine restored with smaller-diameter abutments: a paradigm shift in peri-implant biology

PURPOSE To evaluate the biologic width dimensions around implants with nonmatching implant-abutment diameters. MATERIALS AND METHODS Five canines had their mandibular premolars and first molars removed bilaterally and replaced with 12 implants that had nonmatching implant-abutment diameters. On one side, six implants were placed in a submerged surgical approach, and the other side utilized a nonsubmerged approach. Two of the implants on each side were placed either 1 mm above, even with, or 1 mm below the alveolar crest. Two months later, gold crowns were attached, and the dogs were sacrificed 6 months postloading. Block sections were processed for histologic and histomorphometric analyses. RESULTS The bone level, connective tissue length, epithelial dimension, and biologic width were not significantly different when the implants were initially placed in a submerged or nonsubmerged surgical approach. The bone level was significantly different around implants placed 1 mm above the crest compared to implants placed even with or 1 mm below the alveolar crest. The connective tissue dimension was not different for any implant level placement. The epithelial dimension and biologic width were significantly greater for implants placed 1 mm below the alveolar crest compared to implants placed even with or 1 mm above the alveolar crest. For five of six implant placements, connective tissue covered the implant/abutment interface. CONCLUSIONS This study reveals a fundamental change in the biologic response to implants with nonmatching implant-abutment diameters. Unlike implants with matching implant-abutment diameters, the connective tissue extended coronally past the interface (microgap). This morphologic tissue alteration represents a significant change in the biologic reaction to implant-abutment interfaces and suggests that marginal inflammation is eliminated or greatly reduced in these implant designs.

Is there good simulation basic training for end-to-side vascular microanastomoses?

BACKGROUND Microvascular anastomosis is the cornerstone of free tissue transfers. Irrespective of the microsurgical technique that one seeks to integrate or improve, the time commitment in the laboratory is significant. After extensive previous training on several animal models, we sought to identify an animal model that circumvents the following issues: ethical rules, cost, time-consuming and expensive anesthesia, and surgical preparation of tissues required to access vessels before performing the microsurgical training, not to mention that laboratories are closed on weekends. METHODS Between January 2012 and April 2012, a total of 91 earthworms were used for 150 microsurgical training exercises to simulate vascular end-to-side microanastomosis. The training sessions were divided into ten periods of 7 days. Each training session included 15 simulations of end-to-side vascular microanastomoses: larger than 1.5 mm (n=5), between 1.0 and 1.5 mm (n=5), and smaller than 1.0 mm (n=5). A linear model with the main variables being the number of weeks (as a numerical covariate) and the size of the animal (as a factor) was used to determine the trend in time of anastomosis over subsequent weeks as well as the differences between the different size groups. RESULTS The linear model shows a significant trend (p<0.001) in time of anastomosis in the course of the training, as well as significant differences (p<0.001) between the groups of animals of different sizes. For microanastomoses larger than 1.5 mm, the mean anastomosis time decreased from 19.3±1.0 to 11.1±0.4 min between the first and last week of training (decrease of 42.5%). For training with smaller diameters, the results showed a decrease in execution time of 43.2% (diameter between 1.0 and 1.5 mm) and 40.9% (diameter<1.0 mm) between the first and last periods. The study demonstrates an improvement in the dexterity and speed of nodes execution. CONCLUSION The earthworm appears to be a reliable experimental model for microsurgical training of end-to-side microanastomoses. Its numerous advantages are discussed here and we predict training on earthworms will significantly grow and develop in the near future. LEVEL OF EVIDENCE III This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

From transient to steady state deformation and grain size: A thermodynamic approach using elasto-visco-plastic numerical modeling

Numerical simulation experiments give insight into the evolving energy partitioning during high-strain torsion experiments of calcite. Our numerical experiments are designed to derive a generic macroscopic grain size sensitive flow law capable of describing the full evolution from the transient regime to steady state. The transient regime is crucial for understanding the importance of micro structural processes that may lead to strain localization phenomena in deforming materials. This is particularly important in geological and geodynamic applications where the phenomenon of strain localization happens outside the time frame that can be observed under controlled laboratory conditions. Ourmethod is based on an extension of the paleowattmeter approach to the transient regime. We add an empirical hardening law using the Ramberg-Osgood approximation and assess the experiments by an evolution test function of stored over dissipated energy (lambda factor). Parameter studies of, strain hardening, dislocation creep parameter, strain rates, temperature, and lambda factor as well asmesh sensitivity are presented to explore the sensitivity of the newly derived transient/steady state flow law. Our analysis can be seen as one of the first steps in a hybrid computational-laboratory-field modeling workflow. The analysis could be improved through independent verifications by thermographic analysis in physical laboratory experiments to independently assess lambda factor evolution under laboratory conditions.

The role of diameter versus volume as the best prognostic measurement of abdominal aortic aneurysms

Accurate measurement of abdominal aortic aneurysms is necessary to predict rupture risk and, more recently, to follow aneurysm sac behavior following endovascular repair. Up until this point, aneurysm diameter has been the most common measurement utilized for these purposes. Although aneurysm diameter is predictive of rupture, accurate measurement is hindered by such factors as aortic tortuosity and interobserver variability, and it does not account for variations in morphology such as saccular aneurysms. Additionally, decreases in aneurysm diameter do not completely describe the somewhat complex remodeling seen following endovascular repair of aortic aneurysms. Measurement of aneurysm volume has the advantage of describing aneurysm morphology in a multidimensional fashion, but it has not been readily available or easily measured until recently. This has changed with the introduction of commercially available software tools that permit quicker and easier to perform volume measurements. Whether it is time for volume to replace, or compliment, diameter is the subject of the current debate.

Part two: Against the motion. External diameter for AAA size

Aneurysm diameter measurement is quick and easy, but suffers from the pitfalls of being "too rough and ready". When semi-automated segmentation took 7-10 minutes to estimate volume, it was not a practical tool for busy, routine clinical practice. Today, the availability of automatic segmentation in seconds is bound to make volume measurement, along with 3D ultrasonography, the tools of the future. There can be no debate.

Low-density lipoprotein particle diameter and mortality: the Ludwigshafen Risk and Cardiovascular Health Study.

AIMS The aim of the study was to examine whether differences in average diameter of low-density lipoprotein (LDL) particles were associated with total and cardiovascular mortality. METHODS AND RESULTS We studied 1643 subjects referred to coronary angiography, who did not receive lipid-lowering drugs. During a median follow-up of 9.9 years, 398 patients died, of these 246 from cardiovascular causes. We calculated average particle diameters of LDL from the composition of LDL obtained by β-quantification. When LDL with intermediate average diameters (16.5-16.8 nm) were used as reference category, the hazard ratios (HRs) adjusted for cardiovascular risk factors for death from any cause were 1.71 (95% CI: 1.31-2.25) and 1.24 (95% CI: 0.95-1.63) in patients with large (>16.8 nm) or small LDL (<16.5 nm), respectively. Adjusted HRs for death from cardiovascular causes were 1.89 (95% CI: 1.32-2.70) and 1.54 (95% CI: 1.06-2.12) in patients with large or small LDL, respectively. Patients with large LDL had higher concentrations of the inflammatory markers interleukin (IL)-6 and C-reactive protein than patients with small or intermediate LDL. Equilibrium density gradient ultracentrifugation revealed characteristic and distinct profiles of LDL particles in persons with large (approximately even distribution of intermediate-density lipoproteins and LDL-1 through LDL-6) intermediate (peak concentration at LDL-4) or small (peak concentration at LDL-6) average LDL particle diameters. CONCLUSIONS Calculated LDL particle diameters identify patients with different profiles of LDL subfractions. Both large and small LDL diameters are independently associated with increased risk mortality of all causes and, more so, due to cardiovascular causes compared with LDL of intermediate size.