Internal Knot Research Articles

From inside to outside: CT scanning as a tool to link internal knot structure and external branch diameter as a prerequisite for quality assessment

Branches are as essential for tree growth as knots are detrimental from the wood quality point of view. To bridge the gap between tree growth and the quality toward end-use, this study aims to establish a relationship between internal and external diameters of Douglas-fir whorl branches. The data comprised 102 trees of a wide age range (30–80 years old) from nine study sites in Southwest Germany. External branch measurements were performed in the field following an established protocol. Logs were scanned on a MiCROTEC CT.LOG, and knots were detected by applying an automated algorithm. Obvious detection artefacts by the CT algorithm were excluded to reveal the relationship between inner-outer branch diameters as clear as possible. Results showed a significant mean difference of 13.8 (± 10.0) mm between the methods (external diameter being larger), with a model indicating an offset of 9.75 mm and angular shift of 0.53 (RMSE = 7.12 mm; R2 = 0.57) between the methods. Separate calculations of sound and dead datasets did not reveal a statistically significant difference. By linking the internal knot structure to external branch measurements, the findings of this study constitute a first step toward the incorporation of CT data into growth models, providing a meaningful prediction of the maximum internal knot diameter at an early stage in the wood supply chain.

Predicting Douglas-fir knot size in the stand: a random forest model based on CT and field measurements

Branches are not only of vital importance to tree physiology and growth but are also one of the most influential features in wood quality. To improve the availability of data throughout the forest-to-industry production, information on internal quality (e.g. knots) of both felled and standing trees in the forest would be desirable. This study presents models for predicting the internal knot diameter of Douglas-fir logs based on characteristics measured in the field. The data were composed of 87 trees (aged from 32 to 78 years), collected from six trial sites in southwest Germany, and cut into 4–5 m logs on-site. The internal knot diameter was obtained by applying a knot detection algorithm to the CT images of the logs. Applying the Random Forest (RF) technique, two models were developed: (1) MBD: to predict the branch diameter (BD) at different radial positions within the stem, and (2) MBDmax: to predict the maximum internal branch diameter (BDmax). Both models presented a good performance, predicting BD with an RMSE of 4.26 mm (R2 = 0.84) and BDmax with an RMSE of 5.65 mm (R2 = 0.78). In this context, the innovative combination of CT technology and RF modelling technique showed promising potential to be used in future investigations, as it provided a good performance while being flexible in terms of input data structure and also allowing the inclusion of otherwise underexplored databases. This study showed a possibility to predict the internal diameter of branches from field measurements, introducing an advance towards connecting forest and sawmill.

Simple Endoscopic Application of Laryngeal Keel Stent.

This study describes a simple extraendolaryngeal technique to apply laryngeal keel in dealing with anterior commissure web/fibrosis. Standard extraendolaryngeal punctures were applied via 20-gauge needles, 30° from the skin surface, in midline through the cricothyroid and thyrohyoid membranes. These needles were used as a conduit for the passage of 2/0 Prolene threads, which were retrieved through the laryngoscope by crocodile forceps. Both laryngoscopic ends of the Prolene threads were passed through a fabricated silastic sheet (keel stent) via a 22-gauge free needle, and these ends were tied to have a secure internal knot. Steady traction was applied on the other 2 external threads until there was appropriate application of this keel stent within the vicinity of anterior commissure. Finally, these external ends were tied to have a secure external knot. A keel stent could be applied without the need for special instrumentation and with reasonable outcomes (proper healing of anterior commissure, satisfied voice outcome, and patent airway).

Predictive and prognostic value of HER2 gene expression and HER2 amplification in patients with metastatic colorectal cancer (mCRC) enrolled in CALGB/SWOG 80405 (Alliance).

4086 Background: The randomized phase III CALGB/SWOG 80405 trial found no difference in overall survival (OS) in first-line mCRC pts treated with either bevacizumab (Bev) or cetuximab (Cet) combined with the same chemotherapy. We investigated the potential prognostic and predictive value of HER2 amplification and HER2 gene expression using NGS and Nanostring data. Methods: Primary tumor DNA from 559 patients (pts) was profiled for HER2 amplification by NGS (Foundation One). Tumor tissue from 925 pts was tested for Nanostring gene expression using an 800 gene panel. OS and progression free survival (PFS) were the endpoints as time-to-event variables. Cox proportional hazard models with gene expression fitted with linear spline (one internal knot at median) were used, adjusting for pts baseline characteristics, treatment assignment, and molecular features (microsatellite instability, BRAF, all RAS). Results: Of 505 tumors with both NGS and Nanostring data, 16 harbored HER2 amplification (copy number variation > 6), limited to microsatellite stable tumors and significantly associated with HER2 expression ( P < 0.001) and wild-type RAS ( P = 0.036). HER2 amplification was neither prognostic nor predictive for OS or PFS. Conversely, HER2 expression higher than median was associated with longer PFS ( P = 0.018) but not OS ( P = 0.13). Among pts with HER2 not amplified, higher HER2 expression was associated with better OS (hazard ratio [HR], 0.83; 95%CI, 0.72-0.97; P = 0.016) and PFS (HR, 0.85; 95%CI, 0.74-0.98; P = 0.027) when the expression was less than median. Additionally, in pts with no HER2 amplification and HER2 expression lower than median, treatment with Cet was associated with worse PFS compared to Bev (HR, 1.46; 95%CI, 1.12-1.90; P = 0.005). This effect was not observed with expression higher than median regardless of HER2 amplification status. Conclusions: To our knowledge, this is the largest analysis of HER2 amplification and gene expression in mCRC pts treated with standard therapy. Our results provide novel insight on the predictive and prognostic value of HER2 gene expression in pts treated with Cet- and Bev-based regimens. Upon validation, these findings could inform pts selection and the design of more effective treatment options for pts with low HER2 expression. Clinical trial information: NCT00265850.

Computed tomography (CT) scanning of internal log attributes prior to sawing increases lumber value in white spruce (Picea glauca) and jack pine (Pinus banksiana)

The increased pressure on timber supply due to a reduced forest land base urges the development of new approaches to fully capture the value of forest products. This paper investigates the effects of knowing the position of knots on lumber volume, value, and grade recoveries in curve sawing of 31 white spruce (Picea glauca (Moench) Voss) and 22 jack pine (Pinus banksiana Lamb.) trees. Internal knot position was evidenced by X-ray computed tomography (CT) imaging, followed by the application of a knot-detection algorithm allowing log reconstruction for use as input in the Optitek sawing simulation software. Comparisons of the three levels of sawing optimization (sweep up, shape optimized, and knot optimized) revealed that considering internal knots before log sawing (e.g., knot optimized) generated 23% more lumber value for jack pine and 15% more for white spruce compared with the traditional sweep-up sawing strategy. In terms of lumber quality, the knot-optimized strategy produced 38% more pieces of grade No. 2 and better in jack pine and 15% more such pieces in white spruce compared with the sweep-up strategy. These results indicate a great potential to increase manufacturing efficiency and profitability by implementing the CT scanning technology, which should aid in developing a strong bioeconomy based on an optimized use of wood.

Validation of a CT knot detection algorithm on fresh Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) logs

A fully automated algorithm allowed knot detection and positioning on computed tomography (CT) images of Douglas-fir logs. The detection of knot diameter and status could benefit from further improvements, i.e., testing other configurations and implementing texture measures. Manual measurement on CT images allows for tridimensional assessment and greater attainable sampling, while manual measurement on discs provides additional color and texture information. Computed tomography (CT) is a very successful tool to non-destructively acquire the internal knot structure of a log. To enable large-scale applications, an algorithm that automatically detects knots is required. The accuracy of such algorithms depends heavily on the species and image resolution. This study validates a knot detection algorithm (Johansson et al. in Comput Electron Agric 96:238–45, 2013) on fresh Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) logs. In this study, 282 knots were sampled from 15 logs, selected from six 78-year-old trees in southwest Germany. The validation of the algorithm’s knot detection was performed via comparison against two manual methods: on physical samples and on CT images. The saturated sapwood negatively influences the overall knot detection, which causes underestimation of knot diameter in this area or incomplete detection. The algorithm tended to overestimate knot diameter, longitudinal position, and knot length. The algorithm provides the knot position with satisfactory accuracy. Other settings on contrast and considered volume around a knot can be tested within the algorithm, as well as new development and implementation of texture measures in the image analysis to improve the accuracy results for Douglas-fir in future investigations.

In-and-out technique for intraocular lens scleral fixation.

We describe a modified scleral fixation method to facilitate the good centration and adequate tension of sutures at both ends with addition of an internal fixation knot that reduces decentering of the IOL in a patient with postsurgical aphakia. Using an ab externo suture technique to fixate the haptics to the scleral wall, an additional loop knot is tied 1 mm next to the fixation knot at the haptic. In the technique, an internalized suture and an additional suture knot is tied while holding it close to the fixation knot at the haptic using a needle holder or McPherson forceps. The externalized sutures are secured by taking a bite of transclera and tying the suture to itself. This technique is simple and easy, and adds an internal check valve to prevent excessive pull and decentering of the intraocular lens at one side. The internal check valve also serves as a criterion for the point of fixation at each end.

The Knotted Sky II: does BICEP2 require a nontrivial primordial power spectrum?

An inflationary gravitational wave background consistent with BICEP2 is difficult to reconcile with a simple power-law spectrum of primordial scalar perturbations. Tensor modes contribute to the temperature anisotropies at multipoles with l≲ 100, and this effect — together with a prior on the form of the scalar perturbations — was the source of previous bounds on the tensor-to-scalar ratio. We compute Bayesian evidence for combined fits to BICEP2 and Planck for three nontrivial primordial spectra: a) a running spectral index, b) a cutoff at fixed wavenumber, and c) a spectrum described by a linear spline with a single internal knot. We find no evidence for a cutoff, weak evidence for a running index, and significant evidence for a ``broken'' spectrum. Taken at face-value, the BICEP2 results require two new inflationary parameters in order to describe both the broken scale invariance in the perturbation spectrum and the observed tensor-to-scalar ratio. Alternatively, this tension may be resolved by additional data and more detailed analyses.

Formulation and Comparison of Experimental based Mathematical Model with Artificial Neural Network Simulation and RSM (Response Surface Methodology) Model for Optimal Performance of Sliver Cutting Operation of Bamboo

Bamboo enterprises are continuously sustaining national economy through providing employment opportunities for rural people including raw material collection, processing and marketing. Bamboo has many industrial uses, through this work tried to make the maximum operations feasible so that the machine can prove employment in rural areas at very low manual efforts. This paper reports on design and development of machine with specialty of multiple operations of bamboo processing incorporated in a single machine. It also includes designing of measuring devices for measurement of current drawn, processing torque, Energy, and time required for each processing operations using specially designed electronic kit. The present work reports the design of experimental work to be executed for establishing approximate generalized empirical model for Bamboo(machining properties) processing operations such as cross cutting, external knot removal(two side planning),splitting, internal knot removal, sliver(slats) and stick making, on the basis of experimentation data chosen, using methodology of engineering experimentation. Out of all processing operations, formulation and analysis only for sliver cutting operation is completely mentioned in this paper. The evolution of bamboo machining properties using processing cutters is a complex phenomenon. There are many factors (like geometric variables of machine and bamboo, variation in angular speed, processing torque and variation in current) affecting the performance of bamboo processing machine. This paper presents an experimental investigations and Sequential classical experimentation technique has been used to perform experiments for various sizes of bamboo at different varying speed. An attempt of mini-max principle has been made to optimize the range bound process parameters for minimizing processing torque, Energy, and time required for bamboo Sliver Cutting operation. The test results proved that processing torque, Energy, and time values were significantly influenced by changing important seven dimensionless π terms. The process parameters grouped in π terms were suggested the effective guidelines to the manufacturer for improving productivity by changing any one or all from the available process parameters.

Arthroscopic Glenoid Labral Repair With an Oblique Mattress Configuration

There have been several arthroscopic techniques described in the literature regarding the passage of sutures for an arthroscopic glenoid labral repair. With simple suture passage when tying knots, there is a concern of internal knot impingement, especially in the posterosuperior labrum. On the other hand, with simple suture passage with knotless technology, there is a concern of leaving the anchor hole exposed in the glenohumeral joint space, especially with anchors that are degradable over time. Whereas a horizontal mattress configuration may address these 2 issues in most cases, there is the issue of tissue cut-through with the labral tissue fibers being in the same plane as the horizontal mattress sutures. The purpose of this report is to describe the oblique mattress configuration, which allows the passage of suture through multiple labral tissue planes, covers up the anchor holes with labral tissue, and maintains the knots away from the articular surface if knots are tied.

Sliding internal knot technique for late in-the-bag intraocular lens decentration

We describe a technique that uses a sliding (Siepser) internal knot to secure the intraocular lens (IOL) and capsular bag complex to the sclera. The technique is helpful in cases of late dislocation of the IOL-capsular bag complex, which seems to be particularly common in patients with pseudoexfoliation. The technique, which borrows from earlier techniques, has the advantages of an external approach of the suture needle and a sliding knot with an internal tie that does not require a knot to be covered or rotated.

Predicting knot properties of Picea abies and Pinus sylvestris from generic tree descriptors

Tree models were developed whereby stem shape and internal knot structure of Scots pine and Norway spruce stems could be predicted using site, stand and tree variables. The intention was to develop models that could be applied, using these tree descriptors, to simulate individual knots for sawmill conversion simulation studies. The following independent descriptor variables were used in the models: tree age, crown length, crown ratio, diameter at breast height (DBH), relative DBH, height to the lowest living branch, total height, height above ground, height increment, ring width from the pith to the first 20 years, site index (dominant height at 100 years) and temperature sum (as calculated from altitude and latitude). Knot properties included were maximum and mean knot diameter, individual knot diameter, number of knots per whorl, sound-knot length, loose-knot length and vertical knot inclination. The modelling techniques applied in regression analysis included mixed, general linear, non-linear and segmented models in accordance with the data structure, and in an effort to mimic underlying biological processes (e.g. stand dynamics).

Very strong sutures can still slip: evaluation of five knot types and two suture materials for shoulder arthroscopy (SS-47)

Very strong sutures can still slip: evaluation of five knot types and two suture materials for shoulder arthroscopy (SS-47)

Models of Knots and Log Geometry of Young Pinus sylvestris Sawlogs Extracted from Computed Tomographic Images

The value of solid wood products is largely determined by the sizes, types and distribution of the knots in the products. Hence, there is a great interest in describing the internal knot structure of individual logs. The Swedish Stem Bank has been extensively used for modelling the interior knot structure of Scots pine (Pinus sylvestris L.) and for simulating the outcome of sawing operations. The stem bank holds parametric descriptions, extracted from computed tomographic (CT) imagery, of mature trees. A method for extracting parametric descriptions, in compliance with the stem bank, from young Scots pine sawlogs is presented in this study. A key step in the algorithm is the use of an artificial neural network to find knots in the CT images. The accuracy of the extracted descriptions was evaluated by comparing the size and position of knots measured on 10 real boards with corresponding boards simulated based on the description. The study showed that the number of knots on the real boards was well predicted (R 2=0.90). The differences in tangential and longitudinal position were 0.3±3.6 mm and 1.6±4.2 mm, respectively. The differences in tangential and longitudinal diameter were 0.6±4.0 mm and −0.6±3.9 mm, respectively. Knot diameters were more accurately predicted on boards distant from the pith than on boards close to pith.

Knot Identification from CT Images of Young Pinus sylvestris Sawlogs Using Artificial Neural Networks

The value of solid wood products is to a large extent determined by the sizes, types and distribution of the knots in the products. Hence there is a great interest in describing the internal knot structure of individual logs. The Swedish Stem Bank has been extensively used for modelling the interior knot structure of Scots pine ( Pinus sylvestris L.) and for simulating the outcome of sawing operations. The stem bank holds parametric descriptions, extracted from computer tomography (CT) imagery, of mature trees. To enlarge the stem bank with trees from younger stands, a better method for extracting the knot properties from the CT images is needed. In this study, artificial neural networks were used for segmenting and classifying knots in transverse CT images of a 30-year-old Scots pine. The cross-validated prediction rate of correctly classified pixels was 95.9% - 1.2%. Classified knots were distinctly separated. Misclassifications were mainly located in the border areas between knots and clear

Models of internal knot properties for Picea abies

Models describing the variation in internal knot properties of Norway spruce ( Picea abies (L.) Karst.) in Sweden were developed. The sawlog portion of 114 mature trees was scanned using computer tomography in order to identify internal knots and measure knot dimensions (knot size, sound-knot length, loose-knot length). The variation of both maximum and mean knot diameter per whorl was described in terms of a non-linear segmented (hyperbolic–quadratic–quadratic) model, and as a function of several stand variables, tree variables, and height above ground. The number of knots per whorl was described in a linear model as a function of the distance between whorls and site index. Sound-knot length was modelled in a linear mixed model with knot diameter, height above ground, and diameter at breast height (DBH) as predictors. Loose-knot length was described as a function of relative knot diameter and DBH in a mixed log-linear model. This family of models was intended to be integrated in a decision support system for sawmill conversion simulation studies applicable to merchantable trees in mature stands.

Models of Internal Knot Diameter for Pinus sylvestris

The objective of this investigation was to develop models describing the vertical variation in internal knot size of Scots pine (Pinus sylvestris L.) stems. The sawlog portion of 198 mature trees was scanned using computed tomography in order to measure internal knot size. The variation in knot diameter at the sound/loose knot border was described in terms of a non-linear segmented (hyperbolic-quadratic-quadratic) model, and as a function of stand variables, tree variables and height above ground. A second, simpler (hyperbolic-quadratic) model which was deemed easier to implement was also presented. Although no validation data set was available, the models performed adequately for trees with different growth rates, growing on different sites and being at different stages of development. These results are intended to be integrated in a model system for conversion simulation studies applicable to mature trees.

Variation in knot size of Pinus sylvestris in two initial spacing trials

The objective of this study was to investigate the variation in internal knot size of Scots pine (Pinus sylvestris L.) stems sampled from mature permanent plots, and for which the silvicultural history was known. It was based on a sample of mature trees removed from two different spacing trials representing a moderate and high site index. Knot size was measured with non-destructive methods using a CT-scanner and digital image analysis. Initial spacing varied between 0.75 and 3 m on the high site-index trial and between 1.5 and 2.5 m on the moderate site-index trial. Wider initial spacing on the high site index resulted in larger knots near the base of the stem. However, due to successive thinnings which gradually equalised stand density among plots, the difference between most plots was less further up in the stems. The effect of silvicultural regime was much more limited on the lower site index. Within-stand differentiation resulted in a variation of tree diameter (DBH); larger trees had significantly larger knots. Furthermore, knots were larger towards south than towards north in both trials. These results illustrated that, by using non-destructive measurements on trees sampled from permanent research plots, it was possible to simultaneously study the variation of internal knot size at stand (such as site and silviculture effects), within-stand (such as relative tree size) and within-tree levels (such as height and azimuth). However, lack of replication prevented valid statistical inference as to stand-level effects.