Scar Depth Research Articles

Erosion Wear Behavior of TiAlCrN Coating on Hard Metal Impacted by Solid Particles

The erosion wear resistance of TiAlCrN coating on a hard metal deposited using unbalanced magnetron sputtering technique was investigated by comparison with that of the TiN coating deposited by filtered vacuum arc deposition. SEM was used for observing the surface morphologies of coatings both the un-eroded and eroded. Scratch test was used to evaluate the adhesion of the coatings. The erosion wear was tested with a gas blast apparatus at room temperature. In the test, the coatings were impacted at an impingement angle of 90° by angular SiC solid particles with an average diameter of 124um. The maximum depth of the erosion scar measured by the optical profiler was used to evaluate the erosion wear loss of the coatings. TiAlCrN coating proved to have much lower erosion rate than TiN coating. Different from the typical brittle erosion behavior of TiN coating, the TiAlCrN coating behaved like a semi-brittle material.

Subcision-suction method: a new successful combination therapy in treatment of atrophic acne scars and other depressed scars

Among therapeutic modalities of acne scars, subcision is a simple, safe procedure with a different and basic mechanism for correcting atrophic and depressed scars. Subcision releases scar surfaces from underlying attachments and induces connective tissue formation beneath the scar directly, without injury to the skin surface. Therefore, subcision is a valuable method, but due to high recurrence rate, its efficacy is mild to moderate. To increase the efficacy of subcision, a new complementary treatment of repeated suction sessions was added at the recurrence period of subcised scars. In this before and after trail, 58 patients with mild to severe acne scars of various types (rolling, superficial and deep boxcar, pitted), chicken pox, traumatic and surgical depressed scars were treated by superficial dermal undermining, with mainly 23-guage needles. The protocol for suctioning was: start of suction on third day after subcision for flat and depressing subcised scars and its continuation at least every other day for 2 weeks. Forty-six patients followed the protocol completely, had 60-90% improvement in depth and size of scars (significant improvement) with mean: 71.73%. 28.2% of them had '80% improvement or more' (excellent improvement). Twelve patients started suction late and/or had long interval suction-sessions, had 30-60% improvement (moderate improvement) with mean: 43.75%. Frequent suctioning at the recurrence period of subcision increases subcision efficacy remarkably and causes significant and persistent improvement in short time, without considerable complication, in depressed scars of the face. Therefore, subcision-suction method is introduced as a new effective treatment.

Identification of wear process parameters in reciprocating ball-on-disc tests

Wear test results are presented for a spherical indenter in reciprocal motion interacting with soft (aluminium alloy) and hard (construction steel) substrates. The aim of this paper is to provide evidence of the evolution of the contact zone, specification of wear scar depth and surface roughness in the contact zone. Numerical analysis of the interaction of the sliding sphere with the wear track provided contact zone dimensions, although these differed from the experimental data. The incremental wear factor is also introduced in the paper, while the formulae for the wear volume of the sphere recommended by ASTM have been improved.

High temperature wear and friction behaviour of 15Cr–15Ni–2Mo titanium-modified austenitic stainless steel in liquid sodium

▶ Friction and wear studies of 20% cold-worked 15Cr-15Ni- 2Mo Titanium-modified austenitic stainless steel (alloy D9) in liquid sodium at high temperature. ▶ Low value of friction coefficients for this alloy is due to lubrication mechanism independent of oxygen content. ▶ Values well within the design criteria (as per fuel duct assembly for the Fast Flux Test Facility) for pads of wrapper material for FBRs. The sliding friction and wear behaviour of 15Cr–15Ni–2Mo titanium-modified austenitic stainless steel (alloy D9) was studied in high purity liquid sodium at high temperature viz. 473 and 823 K respectively using a reciprocating-type tribometer. Weight loss measured in specimens after the tests was negligible. Scar depth measurements on disc specimens were carried out by confocal laser scanning microscope, which revealed not much number of scratches tested at 473 and 823 K, respectively. Scanning electron microscopy on worn pin specimens revealed the presence of deformed zone in the rubbed area, and adherence of wear particles at few locations in both the cases. Damage is more in specimens tested at 823 K because of the softening of the rubbing surfaces at that temperature. Further, friction coefficient is lower at 473 K than at 823 K.

Quantitative assessment of direct and indirect landslide risk along transportation lines in southern India

Abstract. A quantitative approach for landslide risk assessment along transportation lines is presented and applied to a road and a railway alignment in the Nilgiri hills in southern India. The method allows estimating direct risk affecting the alignments, vehicles and people, and indirect risk resulting from the disruption of economic activities. The data required for the risk estimation were obtained from historical records. A total of 901 landslides were catalogued initiating from cut slopes along the railway and road alignment. The landslides were grouped into three magnitude classes based on the landslide type, volume, scar depth, run-out distance, etc and their probability of occurrence was obtained using frequency-volume distribution. Hazard, for a given return period, expressed as the number of landslides of a given magnitude class per kilometre of cut slopes, was obtained using Gumbel distribution and probability of landslide magnitude. In total 18 specific hazard scenarios were generated using the three magnitude classes and six return periods (1, 3, 5, 15, 25, and 50 years). The assessment of the vulnerability of the road and railway line was based on damage records whereas the vulnerability of different types of vehicles and people was subjectively assessed based on limited historic incidents. Direct specific loss for the alignments (railway line and road), vehicles (train, bus, lorry, car and motorbike) was expressed in monetary value (US$), and direct specific loss of life of commuters was expressed in annual probability of death. Indirect specific loss (US$) derived from the traffic interruption was evaluated considering alternative driving routes, and includes losses resulting from additional fuel consumption, additional travel cost, loss of income to the local business, and loss of revenue to the railway department. The results indicate that the total loss, including both direct and indirect loss, from 1 to 50 years return period, varies from US$ 90 840 to US$ 779 500 and the average annual total loss was estimated as US$ 35 000. The annual probability of a person most at risk travelling in a bus, lorry, car, motorbike and train is less than 10-4/annum in all the time periods considered. The detailed estimation of direct and indirect risk will facilitate developing landslide risk mitigation and management strategies for transportation lines in the study area.

Effects of Substrate Bias Voltages on the Erosion Wear Resistance of TiN Coatings Deposited by Pulsed Filtered Vacuum Cathode Arc Deposition

TiN coatings were produced on substrates of a hard metal at different bias by pulsed filtered vacuum cathode arc deposition assisted with ion bombardment. The erosion wear resistance of TiN coatings was investigated. The erosion wear was tested with a gas blast apparatus. In the test, TiN coatings were impacted at an impingement angle of 90° by angular SiC solid particles with an average diameter of 124um. The maximum depth of the erosion scar measured by the Veeco NT9300 optical profiler was used to evaluate the erosion wear loss of the coatings. The coatings proved to have lower erosion rate than the substrate material and consequently, the erosion rate increased significantly to the high level of the hard metal substrate after the coatings were penetrated. The results indicated that the TiN coating deposited at 150V bias had the lowest erosion wear rate and best wear resistance. The failure mechanism was revealed by examining the surface morphology of the coatings before and after the erosion test. The erosion wear of the TiN coatings behaved as typical brittle materials.

Erosive wear on ceramic materials obtained from solid residuals and volcanic ashes

In this study, the performance of ceramic materials that were subjected to solid particle erosion was analyzed. This research was performed to characterize the materials in relation to the wear process. The materials could be used in the construction of devices and machine components that are commonly exposed to environments where volatile, abrasive particles typically cause a high rate of wear. The types of composites used in this study could have useful applications in mechanical components, automotive coatings, etc. These materials are usually obtained from solid residuals and volcanic ashes, in which clay and epoxy resin were used as binders. The erosion testing was performed in accordance with the ASTM G76-95 standard. The samples had a rectangular shape, and their dimensions were 50×25 mm 2 and 10 mm in thickness. The abrasive particles used were angular silicon carbide (SiC) with a particle size of 420–450 μm. The tests were performed using three different incident angles (30°, 45° and 90°) with a particle velocity of 24±2 m/s. The abrasive flow rate was 70 g/min. The particle velocity and the abrasive flow rate were low in all the tests to reduce the interaction between the incident particles and the rebounding particles in the system. Additionally, the total time of each test was 10 min, and the specimens were removed every 2 min to determine the amount of mass lost. The test specimens were located a distance of 7 mm from the shot blast. The surface of the specimens was examined with a scanning electron microscope (SEM), which characterized the erosive wear damage. The results indicated that all of the ceramic materials reached their maximum erosion rate at an incident angle of 90°. The erosion rate was significantly decreased when the angle of incidence was 30°. Additionally, the ceramics that consisted of volcanic ashes and sand mixed with epoxy resin gave a better erosion resistance compared with the materials that were combined with clay. It was assumed that the combination that was mixed with epoxy resin produced a more compact structure in the specimens, which resulted in a less severe attack of the particles that were acting on the surface of the material. The sand and the volcanic ashes that were mixed with clay, which had the poorest performance in the tests, exhibited similar behavior. It was also observed that the damaged area was extended in all of the cases that used an incident angle of 45°, whereas the depth of the wear scars was higher when an incident angle of 90° (normal incidence) was used. The wear scars were characterized by an elliptical shape at 30° and 45°, which is a characteristic feature when the specimens are impacted at low-impact angles ( α≤45°), whereas a circular shape was observed at 90°.

Erosion Wear Behavior of Coatings with Growth Defects Produced by Ion Beam Enhanced Pulsed Filtered Vacuum Arc Deposition

The erosion wear behavior of TiN coatings with growth defects was studied. The TiN coatings were produced on a hard metal by ion beam enhanced pulsed filtered vacuum cathode arc deposition. The erosion wear was tested with a gas blast apparatus. In the test, TiN coatings were impacted at an impingement angle of 90° by angular SiC solid particles with an average diameter of 124um. The maximum depth of the erosion scar measured by the optical profiler was used to evaluate the erosion wear loss of the coatings. The coatings proved to have much lower erosion rate than that of the substrate material and consequently, the erosion rate increased significantly to the high level of the hard metal substrate after the coatings were penetrated. The failure mechanism was revealed by examining the surface morphologies of the coatings before and after the erosion test. The erosive wear of the TiN coatings with growth defects behaved as typical brittle materials. The damage mechanism of the coatings with growth defects was described.

Effects of a Skin Rehabilitation Nursing Program on Skin Status, Depression, and Burn-Specific Health in Burn Survivors

The objective of this study was to identify the effects of a skin rehabilitation nursing program (SRNP) on skin status, depression, and burn-specific health in Korean burn survivors. A pretest-posttest design with a nonequivalent control group was used to examine the effects of SRNP for 3 months in a group of 26 burn survivors. The SRNP group of 13 burn survivors received massage therapy 30 minutes three times a week for 3 months compared to a control group of 13 burn survivors receiving typical care. The SRNP group showed no significant changes in the burn scar, subjective skin status, depression, or burn-specific health. Burn survivors receiving SRNP had reduced burn scar depth after the intervention compared to the control group. The findings of this study demonstrate that SRNP for burn survivors may improve burn scars, and findings suggest that future studies with a larger sample should be conducted using SRNP as an intervention for burn survivors.

Successful Treatment of Atrophic Postoperative and Traumatic Scarring With Carbon Dioxide Ablative Fractional Resurfacing

To assess the safety and efficacy of ablative fractional resurfacing (AFR) for nonacne atrophic scarring. In this before-and-after trial, each scar received 3 AFR treatments and 6 months of follow-up. Private academic practice. Fifteen women with Fitzpatrick skin types I to IV, aged 21 to 66 years, presented with 22 nonacne atrophic scars between June 1 and November 30, 2007. Three patients (3 scars) were excluded from the study after receiving 1 AFR treatment and not returning for follow-up visits. The remaining 12 patients (19 scars) completed all 3 treatments and 6 months of follow-up. Each scar received 3 AFR treatments at 1- to 4-month intervals. Erythema, edema, petechiae, scarring, crusting, and dyschromia were graded after treatment and through 6 months of follow-up. Skin texture, pigmentation, atrophy, and overall appearance were evaluated after treatment and through 6 months of follow-up by the patient and a nonblinded investigator. A 3-dimensional optical profiling system generated high-resolution topographic representations of atrophic scars for objective measurement of changes in scar volume and depth. Adverse effects of treatment were mild to moderate, and no scarring or delayed-onset hypopigmentation was observed. At the 6-month follow-up visit, patient and investigator scores demonstrated improvements in skin texture for all scars (patient range, 1-4 [mean, 2.79]; investigator range, 2-4 [mean, 2.95]), pigmentation for all scars (patient range, 1-4 [mean, 2.32]; investigator range, 1-4 [mean, 2.21]), atrophy for all scars (patient range, 1-4 [mean, 2.26]; investigator range, 2-4 [mean, 2.95]), and overall scar appearance for all scars (patient range, 2-4 [mean, 2.89]; investigator range, 2-4 [mean, 3.05]). Image analysis revealed a 38.0% mean reduction of volume and 35.6% mean reduction of maximum scar depth. The AFR treatments represent a safe, effective treatment modality for improving atrophic scarring due to surgery or trauma.

Application of 3-dimensional CT reconstruction in the diagnosis of posterior urethral strictures or ankylurethria

Objective To study the diagnostic value of 3-dimensional CT reconstruction in posterior urethral strictures or ankylurethria.Methods Thirty patients with strictures or ankylurethria of posterior urethra caused by pelvic fracture underwent helical CT scan and 3-dimensional reconstruction of the urethral canal as well as radiographic urethrography before and post open urethral reconstruction to observe the urethral anatomy,the length and position of the urethral strictures,the depth of periurethral scar.Results The mean stricture or ankylurethria length measured by radiographic urethrography was 4.0 cm (range from 1.0 cm to 7.0 cm),and the correlation coefficient of stricture or ankylurethria length was 0.92,21 (70%) patients were diagnosed accurately by radiographic urethrography.The mean stricture or ankylurethria length measured by 3-dimensional CT reconstruction was 4.3 cm (range from 1.2 cm to 7.6 cm),and the correlation coefficient of stricture or ankylurethria length was 0.96,there were 28(93%) patients diagnosed accurately by 3-dimensional CT reconstruction.The mean stricture or ankylurethria length measured by open urethral reconstruction was 4.2 cm (range from 1.5 cm to 7.5 cm).Five patients with urethrorectal fistula were also diagnosed accurately by 3-dimensional CT reconstruction rather than by radiographic urethrography.Conclusions 3-dimensional CT reconstruction of the urethral canal can accurately evaluate the urethral anatomy,the length and position of the urethral strictures,as well as the depth of periurethral scar after crush injury and provide useful information for operation that may not be provided by radiographic urethrography.3-dimensional CT reconstruction may become the most valuable means for detecting posterior urethra strictures or ankylurethria with urethrorectal fistula. Key words: Tomography,spiral computed; Urography Urethral stricture; Diagnosis

Derivation of burn scar depths and estimation of carbon emissions with LIDAR in Indonesian peatlands

During the 1997/98 El Niño-induced drought peatland fires in Indonesia may have released 13-40% of the mean annual global carbon emissions from fossil fuels. One major unknown in current peatland emission estimations is how much peat is combusted by fire. Using a light detection and ranging data set acquired in Central Kalimantan, Borneo, in 2007, one year after the severe peatland fires of 2006, we determined an average burn scar depth of 0.33 +/- 0.18 m. Based on this result and the burned area determined from satellite imagery, we estimate that within the 2.79 million hectare study area 49.15 +/- 26.81 megatons of carbon were released during the 2006 El Niño episode. This represents 10-33% of all carbon emissions from transport for the European Community in the year 2006. These emissions, originating from a comparatively small area (approximately 13% of the Indonesian peatland area), underline the importance of peat fires in the context of green house gas emissions and global warming. In the past decade severe peat fires occurred during El Niño-induced droughts in 1997, 2002, 2004, 2006, and 2009. Currently, this important source of carbon emissions is not included in IPCC carbon accounting or in regional and global carbon emission models. Precise spatial measurements of peat combusted and potential avoided emissions in tropical peat swamp forests will also be required for future emission trading schemes in the framework of Reduced Emissions from Deforestation and Degradation in developing countries.

Acne scarring treatment using skin needling

Acne is a common condition seen in up to 80% of people between 11 and 30 years of age and in up to 5% of older adults. In some patients, it can result in permanent scars that are surprisingly difficult to treat. A relatively new treatment, termed skin needling (needle dermabrasion), seems to be appropriate for the treatment of rolling scars in acne. To confirm the usefulness of skin needling in acne scarring treatment. The present study was conducted from September 2007 to March 2008 at the Department of Systemic Pathology, University of Naples Federico II and the UOC Dermatology Unit, University of Rome La Sapienza. In total, 32 patients (20 female, 12 male patients; age range 17-45) with acne rolling scars were enrolled. Each patient was treated with a specific tool in two sessions. Using digital cameras, photos of all patients were taken to evaluate scar depth and, in five patients, silicone rubber was used to make a microrelief impression of the scars. The photographic data were analysed by using the sign test statistic (alpha < 0.05) and the data from the cutaneous casts were analysed by fast Fourier transformation (FFT). Analysis of the patient photographs, supported by the sign test and of the degree of irregularity of the surface microrelief, supported by FFT, showed that, after only two sessions, the severity grade of rolling scars in all patients was greatly reduced and there was an overall aesthetic improvement. No patient showed any visible signs of the procedure or hyperpigmentation. The present study confirms that skin needling has an immediate effect in improving acne rolling scars and has advantages over other procedures.

Characterization and tribological properties of composite 3Cr13/FeS layer

The 3Cr13 coating was prepared on the surface of 1045 steel by high velocity arc spraying method, and then treated by low temperature ion sulfuration to obtain the solid lubrication composite 3Cr13/FeS layer. SEM was used to observe the surface, cross-section and worn scar morphologies. XRD was utilized to analyze the phase structure. X-ray stress determinator was utilized to measure its residual stress. The nano-hardness and elastic modulus of composite 3Cr13/FeS layer were surveyed by the nano-indentation tester. The tribological properties were investigated on a ball-on-disk wear tester under dry and oil lubrication conditions. The results showed that the friction coefficient and wear scar depth of the composite 3Cr13/FeS layer were always lower than those of FeS film and 1045 steel under dry and oil lubrication conditions. Therefore the composite 3Cr13/FeS layer had excellent Friction-reduction and anti-wear properties.

CROSS technique: chemical reconstruction of skin scars method

Skin scars remain a therapeutic challenge to dermatologists. Over the past several decades, numerous surgical techniques have been used to improve the appearance of scarring. The objective of this study is to evaluate the efficacy of a local application of a (50%) concentration of trichloroacetic acid (TCA) for the treatment of atrophic acne scars (grade 3 in Goodman classification), as opposed to the higher (90%) TCA concentration used in previous studies, in order to reduce adverse local effects. The primary goal was the resolution of acne or chickenpox scars. Secondary goals were physician and subject assessments of scar improvement. Fifty percent TCA was applied locally to atrophic scars in five patients. Three patients had treated scars on the face and two patients had treated scars on the back. Wooden applicators were used to apply TCA locally and the treatment was repeated at 4-week intervals for a total of three sessions. Digital photographic analysis of lesions supported clinical observations. Histologic examination was performed only on two samples of patients with treated scars on the back. Clinical examination revealed cosmetic improvements in both depth and appearance of skin scars. We believe that the 50% TCA CROSS can be an effective technique for the treatment of atrophic scars.

Electroanatomic Characterization of Post-Infarct Scars: Comparison With 3-Dimensional Myocardial Scar Reconstruction Based on Magnetic Resonance Imaging

This study was designed to compare electroanatomic mapping (EAM) and magnetic resonance imaging (MRI) with delayed contrast enhancement (DCE) data for delineation of post-infarct scars. Electroanatomic substrate mapping is an important step in the post-infarct ventricular tachycardia (VT) ablation strategy, but this technique has not yet been compared with a gold-standard noninvasive tool informing on the topography and transmural extent of myocardial scars in humans. Ten patients (9 men, age 71 +/- 10 years) admitted for post-infarct VT ablation underwent both a left ventricle DCE MRI and a sinus-rhythm 3-dimensional (3D) (CARTO) EAM (Biosense Webster, Johnson & Johnson, Diamond Bar, California). A 3D color-coded MRI-reconstructed left ventricular endocardial shell was generated to display scar data (intramural location and transmural extent). A matching process allocated any CARTO point to its corresponding position on the MRI map. Electrogram (EGM) characteristics were then evaluated in relation to scar data. A spiky EGM morphology, a reduced unipolar or bipolar EGM voltage amplitude (<6.52 and <1.54 mV, respectively), as well as a longer bipolar EGM duration (>56 ms) independently correlated with the presence of scar whatever its intramural position. Endocardial scars had a larger degree of signal reduction than intramural or epicardial scars. None of the parameters was correlated with transmural scar depth. A clear mismatch in infarct surface between CARTO and MRI maps was observed in one-third of infarct zones. Sinus-rhythm EAM helps identify the limits of post-infarct scars. However, the accuracy of EAM for precise scar delineation is limited. This limit might be circumvented using anatomical information provided by 3D MRI data.

Wear Evolution in a Stranded Rope Subjected to Cyclic Bending

Wire ropes, due to their construction, combine two very interesting properties: high axial strength and flexibility in bending. However, the assemblage of wires to form flexible ropes results in the sliding of contacting wires and the creation of wear scars, which can act as stress risers and reduce the fatigue life of ropes. Therefore, in order to understand the fatigue behavior of wire ropes, the degradation that occurs between the wires and the strands has to be studied first. In this study, after identifying the main wear patterns for a polymer-covered stranded rope, the wear evolution along the number of cycles and the effect of the sheave diameter in the preferential wear sites were analyzed. The tests were carried out in a custommade Bending over Sheave (BoS) fatigue test bench and short segments of the rope were analyzed by Scanning Electron Microscope (SEM) and confocal imaging profilometry in order to characterize the wear scars. The worn volume and the wear scar depth were selected as the most suitable parameters to characterize the wear behavior of wires. In addition, the importance of the polymeric cover and sheave diameter was proved: a reduction of the sheave diameter results in a bigger wear rate (lm 3 /cycle).

The efficacy of Aloe vera, tea tree oil and saliva as first aid treatment for partial thickness burn injuries

Many alternative therapies are used as first aid treatment for burns, despite limited evidence supporting their use. In this study, Aloe vera, saliva and a tea tree oil impregnated dressing (Burnaid ®) were applied as first aid to a porcine deep dermal contact burn, compared to a control of nothing. After burn creation, the treatments were applied for 20 min and the wounds observed at weekly dressing changes for 6 weeks. Results showed that the alternative treatments did significantly decrease subdermal temperature within the skin during the treatment period. However, they did not decrease the microflora or improve re-epithelialisation, scar strength, scar depth or cosmetic appearance of the scar and cannot be recommended for the first aid treatment of partial thickness burns.

Fretting wear of HVOF Ni–Cr based alloy deposited on SAE 1045 steel

The present study has been carried out in order to investigate the fretting wear performance of a Ni–Cr based alloy, containing B and C, deposited onto a SAE 1045 steel substrate by HVOF thermal spray. Tests were conducted on both the uncoated and coated substrate, under unlubricated dry conditions, at different applied normal loads, cycles and amplitudes in order to analyze the influence of these parameters on the wear behavior. It has been determined that the coated substrate exhibits a very good tribological performance in comparison to the uncoated substrate. The decrease of the wear volume of the coated substrate is of ~ 95–97% of that determined for the uncoated substrate. The increase in the fretting wear resistance provided by the coating has been attributed to the presence of a large amount of dispersed Ni and Cr carbide and/or borides in the Ni–Co matrix. Examination of the fretted surfaces by SEM indicates that the uncoated substrate undergoes an abrasive wear mechanism. On the contrary, it has been observed that the wear mechanism of the coating–substrate system depends on the magnitude of the applied load. At loads of 30 N, a polishing wear mechanism has been determined, whereas between 40 and 50 N, the initiation and propagation of micro-cracks takes place through the coating. The numerical integration of the wear scar depth profile curves employed in the present work allows an estimation of the wear volume which is in good agreement with that determined experimentally by means of 3D profilometry. It has been determined that, at a constant wear amplitude the wear volume increases with the applied normal load and that at under constant load conditions, the wear volume decreases as the wear test amplitude also decreases, becoming insignificant when it is less than ~ 100 µm.

Aspen Height, Stem-girth and Survivorship in an Area of High Ungulate Use

An increase in ungulate population size potentially exposes aspen suckers, saplings, and trees to increased use. This study examined how stem height and girth influenced the selection of stems by ungulates for browsing, rubbing, and gnawing, and reconstructed the history of ungulate use for the study area. Transects were run through each of three aspen clones growing in southwestern Montana to determine height, circumference, and the surface area from which bark was totally and partially removed by rubbing and gnawing. Stems 20–250 cm tall were browsed. Stems 2–13 cm diameter were preferentially selected for rubbing and gnawing. The area of totally removed bark on dead saplings was twice the area of removed bark on live stems of similar diameter, suggesting that bark removal played a major role in the death of some stems. Based on an analysis of stem height and age, ungulate browsing was inferred to have increased from a light-to-moderate level to an intense level in 1991. The depth of scars was used to date scarring events. An increase in rubbing and gnawing was determined to have occurred about 1985. We concluded that elk were primarily responsible for the observed impacts. The combined effect of rubbing, gnawing, and browsing affects a broader span of ages compared to the effect of browsing alone. If prescribed fire is used to rejuvenate aspen stands, the resulting young stems should be protected from heavy browsing, rubbing and gnawing until they reach about 13 cm diameter and have grown out of the browse zone.