Cut Area Research Articles

Application of Er: YAG Laser to Apicoectomy

ently, many studies on the application of Er: YAG laser in the dental field have been reported. Er: YAG laser can ablate dental hard tissues with small thermal damages, and is clinically applied for removal of dental caries. However, there are few studies on apicoectomy using Er: YAG laser. The purpose of this study was to compare apicoectomy using Er: YAG laser and the conventional cutting method in vitro.Extracted single-rooted human teeth were used in this experiment. Root resection was performed with Er: YAG laser (output energy: 70mJ10pps) or a fissure bur mounted to a micro-motor. Resected root surfaces were evaluated with scanning electron microscopy.In addition, cutting efficiency of both methods and dye penetration of the cut surface were compared. After removing the tooth crown of 10 extracted single-rooted human teeth, root canals were cleaned, shaped and obturated. Then, the samples were randomly divided into two groups. Root resection by Er: YAG laser or micro-motor was perfOrtned, and working time was counted and the cut surface area measured. Then, all the root surfaces were sealed with nail polish except the resected surface. All roots were placed into 0.1% methylene blue dye for 7 days, rinsed and air-dried. Finally, they were split and the dye penetration from the resected surface was measured and statistically analyzed.The results were as follows:1. There were no smear layer or debris left on the resected surface cut by Er: YAG laser, and the shape of the cut surface was irregular. On the other hand, both smear layer and debris were observed on the surface cut by the conventional method, and the cut surface was smooth.2. The cutting efficiency of Er: YAG laser and micro-motor was 14.8 (±7.3) sec./mm2 and 4.4 (±1.7) sec./ram2, respectively. Cutting by Er: YAG laser significantly needed more time than that by micro-motor (t-test, P<0.05).3. Dye penetration length in the Er: YAG laser group and micro-motor group from the resected surface was 0.95 (±0.37) mm and 1.07 (±0.70) mm, respectively. There was no significant difference between the two groups.(J. Jpn. Soc. Laser Dent. 8: 23-30, 1997 Reprint requests to Dr. EBIHARA)

Effects of Cutting Modes on the Ripening and Quality Changes in Fresh-cut Green Banana

Fresh-cut green bananas (non-C2H4 treated) were prepared in the following four styles : 7cm-long and 1cm-thick sections cut longitudinally (LCS), 1cm-thick crosswise sections cut transversely (0 CCS), and cut obtusely to the transverse at 30° (30 CCS) or 60° (60 CCS). Each section packed in polyethylene bags was stored at 20°C. I. The cut surface area and weight of LCS were the largest, followed by 60 CCS, 30 CCS, and 0 CCS, but no major differences were found in the ratio of the surface area/weight among sections. 2. The color in the peel of all sections changed during 6 days storage. The LCS began to yellow most rapidly, followed by 30 CCS, 60 CCS, and 0 CCS. The concentrations of C2H4 and CO2 in polyethylene (PE) bags were the highest with LSC and those of the CCSs increased with increasing the obtuse angles until day 3. 3. The respiration rate (CO2 production) of the intact green bananas increased slowly during 7 days storage. The respiration rate of LCS increased rapidly, and that of CCSs increased until day 4, the increase being greater in 60 CCS. Ethylene production was not detectable from intact green bananas during 6 days storage. The LCS showed the increase of C2H4 production and the peak of production was on day 2. The 60 CCS showed the peak on day 3 and the C2H4 production rate of the 30 and 0 CCS reached the peak on day 5. The peak of 30 CCS was higher than that of 0 CCS. 4. There were significant linear increase in sugar content and decrease in starch content of pulp in all sections during 6 days storage. The LCS showed these changes most rapidly followed by 60 CCS, 30 CCS, and 0 CCS. 5. It appears that the cutting of green banana fruits induces the activation of physiological and chemical changes, and these changes are associated with cutting direction.

The critical point and related symmetry measures of a planar convex set

The critical point and related invariant points of a planar convex set are computed using an exhaustive search strategy based on a formulation due to Neumann. Algorithms to compute the critical point based on the Minkowski formulation and Euclidean duality is also presented. The functionals associated with the critical points are illustrated, and computational experience lends support to a conjecture due to Neumann in regard to the lower bound of a perimeter functional. Related symmetry measures based on cut areas and chords are also examined.

Treatability of several Greek wood species with the water soluble preservative CCB

Roudwood from 7 softwood and 17 hardwood Greek species (length 1,20 m, diameter 14–20 cm) or/and sawn timber (length 1,25 m, cross section 5 cm × 7 cm) were impregnated with 2% CCB in the full cell process. Based on the dry salt retention, on the impregnated cross cut area, on the lateral and axial penetration and on the distribution of the preservative on cross sections, the wood species were classified according to their treatability into six classes: Very Permeable, Permeable, Moderately Permeable, Resistant, Very Resistant and Impermeable.

Effect of Knife Angle and Velocity on the Energy Required to Cut Cassava Tubers

Experiments were conducted to determine the optimum values of cutting velocity, knife bevel angle and shear angle (angle of cut with respect to the longitudinal axis of the tuber) on the energy required to cut the tubers. The results suggest that the specific cutting energy of the tuber (cutting energy per unit area of cut) was minimum for cutting velocities in the region of 2·5 m/s, shear angles of 60° to 75° and bevel angles of 30° to 45°.

Allorecognition responses in the soft coral Parerythropodium fulvum fulvum from the Red Sea

Allogeneic encounters were experimentally arranged in Eilat, Red Sea for the first time in the Alcyonacea with the soft coral Parerythropodium fulvum fulvum. All possible pairwise combination assays within two groups of five colonies each and one group of three colonies were setup in situ in 2–4 replicates each (a total of 76 assays). Control isogeneic encounters always resulted in complete tissue fusion. Two types of allogeneic responses were documented following tissue-totissue contacts. The first was retreat growth, in which contacting allografts started to retreat from each other a few days following direct contact until a bare area of a few mm separated them. In several assays the colonies repeatedly grew into contact and retreated again. The second allogeneic response was unilateral or reciprocal tissue overgrowth. In this type of response one colony overgrew the conspecific partner by several mm and then stopped. The underlying tissue of the overgrown partner died. No cytotoxicity was observed in allogeneic contacts either in growing parts or when assays were established between cut surface areas. Repeated assays of the same pair-combination were not consistent in terms of type and directionality of responses. We propose that effector mechanisms elicited following allogeneic encounters in P.f. fulvum may be affected by biological as well as non-biological parameters and are not specific to the type of allogeneic challenge. However, colony specificity in this species is restricted only to the level of self- and non-self discrimination.

Influence of irradiance on branch growth of white clover stolons in rejected areas within grazed swards

AbstractDevelopment of white clover stolons (Trifolium repens) was compared when grown in rejected areas and in adjacent defoliated areas over 28 days in May ‐ June in continuously stocked grass/white clover swards. In the cut areas more branches were borne on stolons with more but shorter internodes and shorter petioles than in the rejected areas. Red (R)/far red (FR) ratio at the base of the cut sward was significantly higher than in the rejected sward.Five experiments were carried out in which red light‐emitting diodes (LEDs) supplied supplementary irradiation at the node of the youngest fully expanded leaf on white clover stolons growing in association with dense canopies of perennial ryegrass. Axillary bud/branch length was the only significantly affected aspect of development that was measured, irradiation enrichment increasing length by about three‐fold over a 2–4 week period. One of the experiments involved identification of the site of perception of the R/FR effect. Natural and supplementary light were excluded from the stolon (by covering with a 2‐cm layer of black beads), petiole (by wrapping in aluminium foil), both or neither and showed that exposure of the stolon/ petiole base to supplementary light was necessary to stimulate axillary bud growth.It is concluded that the relative content of red light, and possibly absolute level, in irradiance at the base of the canopy in rejected areas is implicated in the young branch growth and that release of the buds can be achieved by defoliation, presumably due to increasing the red light content; however, the effect of increased photosynthetically active radiation (PAR) reaching stolons and young leaves cannot be discounted as an additional factor.

The micro-meniscus effect of a thin liquid film on the static friction of rough surface contact

A numerical method has been developed to account for the micro-meniscus effect of an ultra-thin liquid film on the static friction of rough surface contact. The classical meniscus theory of a single-sphere contact was modified to include the effect of multiple asperity contacts with a pre-existing ultra-thin liquid film during the contact of two rough surfaces. The effect of micro-meniscus formation was considered in terms of elastic - plastic deformation of rough surfaces under applied load, roughness parameters, thickness of liquid film and meniscus height. In the numerical model, elastic - plastic dry contact of rough surfaces is first analysed. In the next step, a liquid film of known mean thickness is introduced over the deformed rough surfaces. Wetted areas are determined by selecting the areas where asperities of both contacting surfaces touch the liquid. The total projected meniscus area is determined by selecting those area islands of cross cut area at a given mean meniscus height which overlap the wetted area. The meniscus force is then calculated using the meniscus equation derived from first principles of the micro-meniscus theory. Two parameters, meniscus height and liquid film thickness, are required for the analysis, which can be obtained for a given relative humidity. However, for a given liquid-film thickness, meniscus height is a function of liquid-film thickness and needs to be estimated. The present numerical method was applied to data-processing magnetic rigid disk drives to analyse the static friction during contact in the presence of an ultra-thin liquid film on one of the surfaces. Trends in numerical predictions correlate well with the measured effect of liquid films on the static friction. The analysis reveals some new insights into the `stiction' problems of disk drives.

Evaluation of Seasonal Variability in Cohesive Subgrades Using Backcalculation

Seasonal variation in pavement strength is an important concern for engineers and transportation authorities. In 1990, an investigation was initiated that aimed at quantifying seasonal variations within a typical cohesive subgrade soil in Alberta. The study consisted of two phases: a field investigation phase and a laboratory testing program. The field phase involved instrumenting a pavement section that is representative of the primary highway system in Alberta with thermal conductivity suction sensors. Falling weight deflectometer (FWD) deflection tests were conducted at regular time intervals over a period of 2 years and at various locations within this section. Effective pavement layer moduli were backcalculated using measured deflections, and the results were plotted versus time to quantify seasonal changes occurring in pavement structural strength. Only the research findings obtained from the FWD deflection tests that deal primarily with subgrade moduli are discussed. Remaining field data represent a valuable resource to researchers investigating other pavement structural factors. Use of the backcalculation approach for quantifying seasonal variations in subgrade stiffness seems promising. Following a significant reduction in subgrade stiffness upon thawing, a long period of relatively constant strength prevails. After that a period of gradual recovery and subsequent increase in strength is experienced as freezing approaches. Backcalculated subgrade fill moduli were found to be 65 percent greater than their counterparts in cut areas. Furthermore, the subgrade fill moduli were observed to experience less seasonal fluctuation than the cut moduli. Finally, the backcalculated subgrade moduli were found to be insensitive to asphalt concrete surface temperature influences.

Grading Design of Side Slopes Fitting Roadside Topography

Preparing the grading plan of the side slopes on a highway section is an effective way to obtain an overall three-dimensional view of the entire design area, and a design fitting the roadside topography. Flattening the slope on the ends where the cut or fill is light and gradually steepening it toward the controlling maximum is suggested by the American Association of State Highway Transportation Officials (AASHTO) in order to achieve a smooth appearance. In the present technical note a method to obtain this goal is proposed and applied to a highway's cut area. Depending on the slope's height two different slope ratios are used. Cut slopes are rounded using a parabolic curve with a vertical axis centered on the point of intersection of the original ground surface and the backslope. The length of the curve is determined according to the slope height. The method suggested in the present technical note is a simple and effective way to produce a successful sideslope grading design.

Changes in Albedo of a Northern Hardwood Forest Following Clearcutting

Abstract A semi-empirical model designed to stimulate seasonal and midsummer albedo of a northern tolerant hardwood stand following clearcutting was developed from field determinations conducted in west-central New Brunswick. In this model, changes in albedo are related to (1) vegetative regrowth (spreading of newly developing foliage over the cut area); (2) the gradual addition of vegetation layers within the forest canopy; and (3) seasonal variations from bud burst to fall. The field data indicated that (1) cutting reduced the albedo; (2) foliage regrowth rapidly increased the albedo to a maximum similar to that of a continuous single leaf layer within a few years after the cutting operation; (3) deepening of the canopy gradually decreased the albedo after its initial peak; and (4) albedo values were highest in early summer, except in the first year after the cutting operation. For. Sci. 41(2):268-277.

Moisture Diffusion Behaviour of T300-914C Laminates

This paper presents the moisture diffusion characteristics of autoclave moulded T300-914C unidirectional composite specimens hygrothermally conditioned at 85% RH and 70'C till saturation to 1.5% moisture content. In all, pin bearing strength test specimens of three different layup sequences viz. [45/03/ A 45/03/90/0],, [0/ 4 45/9012s and [45/02/45/03/45/0], were studied. All the test specimens exhibited Fickian Diffusion behaviour. It was further found that the Diffusion coefficient (D,) value of the composites increased with increase in the cut edge surface area and the values obtained compared well with those reported in literature. The difference in D, values obtained for different layup sequences was attributed to tortuousity caused by fibre orientations.

Computer-aided generation of the cutting conditions in pocket machining

To improve cutting performance, a geometric modeling system is applied to an in-process simulation of the cutting geometry in pocket machining. Based on this developed system, the area of the chip cut is identified and then the corresponding cutting performance is evaluated and optimized by an automatic modification of NC codes. Experimental results are provided to support the feasibility of the proposed system.

Capercaillie (Tetrao urogallus) Lekking sites in fragmented Finnish forest landscape

The location of Capercaillie lekking sites was compared in forest mosaics of different level of fragmentation. In north Finland the stand characteristics of the lekking sites did not differ from those of randomly selected stands in the 1950s judged from forestry maps and stand registers. In the 1980s, when forestry had considerably altered stand structure, lekking stands were older, larger and had a higher timber volume than random stands. These features evenly changed from the lek centre to the distance of 4 km, to which distance the adjacent areas were assessed. Southern and central Finnish analyses, based on topographic maps, showed that the proportion of forest distinctly decreased with increasing distance from a lek centre, up to a distance of 1–1.5 km. The average patch size of lekking stands were largest in the north (where both cut areas and remaining stands are large) and smallest in central Finland dominated by fine‐grained forest landscape. The results are discussed in terms of landscape ecolog...

Immunohistological differentiation of benign thyroid follicular cell tumors from malignant ones: usefulness of anti-peroxidase and JT-95 antibodies.

An immunohistological investigation using anti-thyroid peroxidase (PO) and JT-95 (JT) antibodies was conducted on surgical specimens of papillary carcinoma (n = 12), follicular carcinoma (n = 8), follicular adenoma with prominent papillary structure (n = 12), follicular adenoma (n = 8) and adenomatous goiter (n = 8). In benign lesions, follicle-forming and papillae-forming epithelia showed positive staining with anti-PO antibody. In 26 of 28 benign lesions, PO-positive areas covered 50% or more of the cut surface area of the lesions. However in carcinomas, PO-positive areas were non-existent (13/20) or only focal (7/20) and the papillae did not stain. The incidence of JT-positive cases was higher in papillary carcinomas (12/12) than in other lesions (13/36). JT-positive areas were much wider than PO-positive areas in papillary carcinomas, whereas in benign lesions, PO-positive areas were wider than or at least roughly equal to, JT-positive areas. Follicular carcinomas did not stain or stained only focally with these antibodies. In conclusion, these two antibodies seem useful in differentiating benign from malignant follicular cell tumors.

Survival of woodland caribou in commercial forests of northern Ontario

Telemetry, sightings, and tracks in snow from 1978–81, with subsequent observations until 1991, showed that woodland caribou (Rangifer tarandus caribou) did not use cut portions of traditional wintering areas for 12 years after cutting. Two attempts by management personnel to modify commercial cutting patterns for caribou failed to prevent abandoning cut areas. In four instances where entire wintering areas were cut, caribou sightings and tracks decreased drastically or ceased entirely. Caribou in unlogged areas have shown no similar declines. Minimal efforts to ensure caribou survival in commercial forests should include deferral of cutting in caribou wintering areas, protection of calving areas, and accelerated research. Keywords: woodland caribou, forest management, threatened population, wildlife conservation

Microvascular architecture of early gastric carcinoma. Microvascular-histopathologic correlates.

Gastric carcinoma is clinicopathologically divided into differentiated and undifferentiated types. The former is grossly protuberant and often causes hematogenous metastasis to the liver or lung, whereas the latter is mostly depressed or ulcerated from its early stage and rarely causes blood-borne metastasis. The purpose of this study is to clarify the microvascular architecture of early gastric carcinoma with reference to the histologic subtypes. A silicone rubber compound (Microfil) injection method with a methyl salicylate clearing technique was used in 32 resected early gastric carcinomas. The microvascular architecture was observed both in the carcinoma and its surrounding noncancerous tissue in each specimen under a stereomicroscope and light microscope. Compared to the surrounding normal mucosa, the differentiated carcinomas (DC) mostly were hypervascular (24%) or normovascular (65%), whereas the undifferentiated carcinomas (UC) often were hypovascular (60%). Irregularity of tumor vessels (67%) and an arcade-like appearance (33%) was encountered frequently in UC, whereas hypervascularity of the surrounding noncancerous mucosa (29%) often was noticed in DC. Quantitative analysis, including vascular volume, mean vascular diameter, and cut section area, supported these differences between DC and UC. The results suggest that vascular structures of gastric carcinomas are characteristic with regard to their histologic subtypes; DC is normovascular or hypervascular, whereas UC is hypovascular.

Consequences of the Swedish forest policy

This article demonstrates that the opportunity cost (return forgone) of cutting principles imposed by the Swedish forest policy is economically significant. The Swedish Forestry Act of 1979 recommends a management strategy for sustaining high yields of valuable timber referred to here as the Balance Strategy. However, the Forestry Act allows for a range of different forest management strategies. The Act establishes both a minimum cutting volume for a ten‐year‐period and a maximum final cut area referred to here as the Minimum and Maximum Strategies, respectively. These strategies were compared to a management plan, referred to as the Economic Strategy, for minimizing the opportunity cost for the forest owner. Based on data from a recent forest management plan, a simulation model was used to predict yields and economic returns for a period of one hundred years. The results show that at a 4% interest rate the Economic Strategy produces a gain of approximately 8200 SEK ha‐1. The Economic Strategy, however, e...

The effect of transforming growth factor-α on airway angiogenesis

A problem in lung transplantation is tracheal or bronchial dehiscence from ischemia. To determine if an angiogenic factor applied to the airway would improve capillary regrowth, a three-ring segment of trachea was completely severed and sutured in rats. In one group of animals the ischemic segment was wrapped with Gelfoam soaked in an angiogenic factor, transforming growth factor-alpha. In a second group the ischemic area was wrapped with Gelfoam soaked with only the vehicle. In a third group the devascularized area received no additional treatment. One animal from each group was killed daily for 7 days after operation. The tracheal vasculature was cast and viewed by light and scanning electron microscopy. None of the four animals that died early were in the transforming growth factor-alpha group. All animals lost weight between the day of operation and death, but this was least in the transforming growth factor-alpha group (p = 0.05). The light microscopy showed ischemic changes and the development of granulation tissue. The scanning electron microscopy of the vascular casts showed extensive loss of the vessels in the cut area. On day 1 the vessels of all animals dilated and their walls became rough. By day 3 a few corkscrew vessels penetrated the ischemic zone. By day 4 the animal that received transforming growth factor-alpha had more capillaries than the others. By day 6 revascularization in the transforming growth factor-alpha animal was abundant. Besides budding, new capillaries appeared to develop by lateral growth. After the fifth day vessels about 30 to 50 microns in diameter bulged focally. On the bulges, ridges the size, shape, and pattern of capillaries formed. Capillary formation in this manner has not been reported previously. Revascularization emerged sooner and more extensively with transforming growth factor-alpha. No adverse effect of transforming growth factor-alpha was found.

Multifocal cerebral blood flow by Xe-CT and global cerebral metabolism after prolonged cardiac arrest in dogs. Reperfusion with open-chest CPR or cardiopulmonary bypass.

Using the stable xenon-enhanced computed tomography (Xe-CT) method in dogs, we studied local, regional and global cerebral blood flow (LCBF, rCBF and gCBF) in two sham experiments and nine cardiac arrest experiments. Within the same experiments without arrest, gCBF and rCBF values were reproducible and stable. LCBF values varied over time. In group I (n = 4), ventricular fibrillation cardiac arrest (no blood flow) of 10 min was reversed by open-chest cardiopulmonary resuscitation (CPR). In group II (n = 5), ventricular fibrillation cardiac arrest of 12.5 min was reversed by brief closed-chest cardiopulmonary bypass. This was followed by controlled ventilation, normotension, normoxia, normocarbia and normothermia to 4 h (n = 7) or 20 h (n = 2) postarrest. The postarrest CBF patterns were similar in both groups. Open-chest CPR during ventricular fibrillation generated near-baseline gCBF and lower LCBF ranges. During postarrest spontaneous circulation, transient diffuse hyperemia was without low-flow regions, longer in brain stem and basal ganglia than in neocortex. During delayed hypoperfusion at 1-4 h postarrest (n = 9), mean gCBF was 44-60% baseline, rCBF in primarily gray matter regions was 15-49 ml/100 cm3 per min and LCBF voxels with trickle-flow and low-flow values, in percent of CT cut area, were increased over baseline. Global CMRO2 (n = 3 of group II) recovered to near baseline values between 1 and 4 h postarrest, while gCBF and O2 delivery were about 50% baseline (mismatching of O2 uptake and O2 delivery).