Piston slap is a major source of vibration and noise in internal combustion engines. Therefore, better understanding of the conditions favouring piston slap can be beneficial for the reduction of ...engine Noise, Vibration and Harshness (NVH). Past research has attempted to determine the exact position of piston slap events during the engine cycle and correlate them to the engine block vibration response. Validated numerical/analytical models of the piston assembly can be very useful towards this aim, since extracting the relevant information from experimental measurements can be a tedious and complicated process.
In the present work, a coupled simulation of piston dynamics and engine tribology (tribodynamics) has been performed using quasi-static and transient numerical codes. Thus, the inertia and reaction forces developed in the piston are calculated. The occurrence of piston slap events in the engine cycle is monitored by introducing six alternative concepts: (i) the quasi-static lateral force, (ii) the transient lateral force, (iii) the minimum film thickness occurrence, (iv) the maximum energy transfer, (v) the lubricant squeeze velocity and (vi) the piston-impact angular duration.
The validation of the proposed methods is achieved using experimental measurements taken from a single cylinder petrol engine in laboratory conditions. The surface acceleration of the engine block is measured at the thrust- and anti-thrust side locations. The correlation between the theoretically predicted events and the measured acceleration signals has been satisfactory in determining piston slap incidents, using the aforementioned concepts. The results also exhibit good repeatability throughout the set of measurements obtained in terms of the number of events occurring and their locations during the engine cycle.
•Six methods are used to identify piston slap events in internal combustion engines.•The number of slap events increases as the engine speed increases.•Quasi-static/transient force methods can predict slap position at lower engine speed.•The transient minimum film thickness method is more successful at higher engine speed.•The piston-impact angular duration method predicts slap events through all tests.
The glenoid labrum is a fibrocartilaginous ring that affixes the joint capsule and ligaments of the glenohumeral joint2. Superior labrum anterior to posterior (SLAP) lesions are a subset of injuries ...that affect the superior glenoid labrum, most common in laborers and overhead-throwing athletes11. In 1990, Snyder et al classified SLAP lesions into one of four types10. Later, Maffet et al expanded this scale to include three additional subclassifications8. At present, arthroscopy is considered the gold standard for SLAP tear diagnosis5. Classification under arthroscopy has demonstrated low to moderate inter-rater reliability3. MRa is an alternate, less invasive test for diagnosing SLAP lesions. The reliability of MRa for diagnosing slap tears is uncertain.
MR arthrograms were identified using the Picture Archiving and Communication System (PACS). In total, 273 shoulder arthrograms were reviewed, and 20 were selected with the desired pathology. Three orthopedic surgeons and three musculoskeletal radiologists were asked to classify the SLAP lesions into one of seven categories (Snyder & Maffet classification systems). Data was collected on two separate occasions at an interval of at least two months. Inter- and intra-rater reliability were calculated using Fleiss Kappa and Cohen's Kappa, respectively.
Between all raters, there was poor inter-rater reliability for each round of data collection (κ = .177, κ = .124 for rounds 1 and 2, respectively). Between orthopedic surgeons, there were poor levels of agreement (κ = -.056, κ = .114), whereas, between radiologists, there was fair to moderate agreement (κ = 0.479, κ = 0.340). Within orthopedic raters, κ values ranged from -0.059 to 0.125, indicating, at best, poor intra-rater reliability. Within radiologists, κ values ranged from 0.545 to 0.553, indicating moderate agreement within raters. The analysis determined that none of the orthopedic values for inter or intra-rater reliability could be deemed statistically different from zero.
Overall, classification using MRa resulted in significant disagreement between and within raters. Trained radiologists demonstrated higher overall levels of agreement than orthopedic surgeons. In summary, when using MRa to assess SLAP lesions, Snyder and Maffet classification demonstrates poor reliability by orthopedic surgeons and moderate reliability when used by musculoskeletal radiologists.
Superior labrum anterior-posterior (SLAP) tears are common shoulder injuries, especially in overhead athletes. Often, initial management of these injuries is nonsurgical with focused rehabilitation. ...The purpose of this review was to evaluate the outcomes of nonsurgical management of SLAP tears in athletes.
A systematic review was performed for articles published before March 2021 using key search terms pertaining to clinical studies evaluating the nonsurgical treatment of SLAP tears in adult patients published in English-language literature. Abstracts and manuscripts were independently reviewed by 2 co-authors to determine eligibility. Return-to-play rate and return-to-prior-athletic-performance rate were determined by combining results across studies.
Five articles met the inclusion criteria. There were 244 total athletes (162 elite or higher-level athletes). The mean ages ranged from 20.3 to 38.0 years. Type II SLAP tears were most common; baseball, softball, and weightlifting were the most common sports involved. The return-to-play rate was 53.7% in all athletes and 52.5% in elite or higher-level athletes. In athletes who were able to complete their nonoperative rehabilitation program, the return-to-play rate was 78% in all athletes and 76.6% in elite or higher-level athletes. The overall rate of return to prior performance was 42.6%, which increased to 72% for those athletes who were able to complete their rehabilitation. Patients who discontinued the rehabilitation protocol in favor of surgery had an average of 8 physical therapy sessions compared with 20 sessions for patients with successful nonoperative treatment. The timing of return to play was generally less than 6 months in studies that reported it. Patient-reported outcomes, including the American Shoulder and Elbow Surgeons score and visual analog scale, all improved significantly after nonsurgical treatment. Factors associated with failure of nonsurgical management included older age, participation in overhead sports (especially baseball pitchers), traumatic injury, positive compression rotation test, concomitant rotator cuff injury, longer baseball career, longer symptomatic period, and the presence of a Bennett spur.
Overall, nonoperative treatment of SLAP tears in athletes can be successful, especially in the subset of patients who are able to complete their rehabilitation program before attempting a return to play. Although nonoperative treatment should be considered the first line of treatment for most SLAP tears, there are some factors that may be associated with failure of conservative treatment; therefore, further high level, prospective studies would be beneficial to identify those athletes most likely to respond favorably to nonoperative treatment.
Background:
Superior labral anterior-posterior (SLAP) lesions are common among elite gymnasts and throwing athletes. Although SLAP lesions in throwers are well-described in the literature, no study ...has described the characteristics of SLAP lesions in gymnasts. We aimed to reveal the characteristics of SLAP lesions in gymnasts by comparing the location and extension of these lesions between gymnasts and throwers.
Hypothesis:
The location and arc of SLAP lesions in gymnasts will be different from those in throwing athletes.
Study Design:
Case series; Level of evidence, 4.
Methods:
This study included 27 shoulders in 20 males and 3 females with a mean ± SD age of 20 ± 2.5 years (range, 16-25 years). We performed debridement alone for shoulders with a stable lesion. Anterior and/or posterior labral repair was added for unstable SLAP lesions depending on the extension and stability of the lesions. We investigated symptoms, onset, return to sport (based on patient records), and subjective shoulder values. SLAP lesions were evaluated through use of the Snyder classification. The location and arc of SLAP lesions were determined from surgical records and videos and described by use of the right shoulder clockface method. During the same period, 65 baseball players (65 shoulders; all males; mean age, 23 ± 7.0 years; range, 16-44 years) underwent arthroscopic SLAP surgery. We compared the location and arc of SLAP lesions between gymnasts and baseball players.
Results:
Symptoms during gymnastics included pain (100%), apprehension (48%), or catching (11%). We found that 20 shoulders had symptom onset during gymnastics, most commonly during rings events. Type II SLAP lesions were found in 17 shoulders, type III in 2 shoulders, and type IV in 8 shoulders. The mean center of SLAP lesions was at the 11:40 clockface position in 27 gymnasts and 10:40 clockface position in 65 baseball players, and the difference was statistically significant (P < .001). The mean arc of SLAP lesions was 125° in gymnasts and 140° in baseball players, and the difference was not significant. We performed debridement in 2 shoulders (7%) and labral repair in 25 shoulders (93%). After surgery, all patients returned to gymnastics. The mean subjective shoulder value was 35 (range, 10-90) preoperatively and 76 (range, 40-100) postoperatively.
Conclusion:
SLAP lesions in gymnasts were significantly located anteriorly compared with those in baseball players. All patients returned to gymnastics after arthroscopic surgery. Secure repair of SLAP lesions may be important for good surgical outcomes, because 50% of patients experienced preoperative shoulder apprehension.
Every day, billions of fingerprint images are captured worldwide through the extensive deployment of slap-fingerprint acquisition devices, serving e-governance programs and bolstering national border ...security. Several studies from national ID programs, like UIDAI and NIST, have indicated that about 2% of the user population may lack usable fingerprints. Finger knuckle patterns are inherently presented during such slap-fingerprint acquisition and can be simultaneously acquired without imposing any additional inconvenience on the users. Leveraging these finger knuckle patterns can enable not only significant improvement in identification accuracy but also enhance overall protection and facilitates smoother traffic flow. This paper develops the first such finger-knuckle-assisted fingerprint identification system for real-world applications. We systematically develop automated finger knuckle detection and segmentation algorithms, for multiple knuckles and under complex illumination, for such contactless images from the deployed slap fingerprint devices. Currently, available algorithms offer limited performance for such images, and therefore this paper proposes a new approach to more accurately match such knuckle images. Our experimental results illustrate the significant performance improvement over existing knuckle matching algorithms, and further by incorporating dynamic fusion capabilities. This paper also introduces the first joint finger-knuckle and fingerprint database, from 120 different subjects, in the public domain to advance further research and development efforts needed in this area.
The S-layer proteins are a class of self-assembling proteins that form bi-dimensional lattices named S-Layer on the cell surface of bacteria and archaea. The protein SlpA, which is the major ...constituent of the
S-layer, contains in its C-terminus region (SlpA
), a protein domain (named here as SLAP
) responsible for the association of SlpA to the bacterial surface. SLAP
was adapted for the development of a novel affinity chromatography method: the SLAP
-based affinity chromatography (SAC).
Proteins with different molecular weights or biochemical functions were fused in-frame to the SLAP
and efficiently purified by a
-derived affinity matrix (named Bio-Matrix or BM). Different binding and elution conditions were evaluated to establish an optimized protocol.
The binding equilibrium between SLAP
and BM was reached after a few minutes of incubation at 4°C, with an apparent dissociation constant (K
) of 4.3μM. A reporter protein (H6-GFP-SLAP
) was used to compare SAC protein purification efficiency against commercial immobilized metal affinity chromatography. No differences in protein purification performance were observed between the two methods. The stability and reusability of the BM were evaluated, and it was found that the matrix remained stable for more than a year. BM could be reused up to five times without a significant loss in performance. Additionally, the recovery of bound SLAP-tagged proteins was explored using proteolysis with a SLAP-tagged version of the HRV-3c protease (SLAP
). This released the untagged GFP while the cut SLAP
and the SLAP
were retained in the BM. As an alternative, iron nanoparticles were linked to the BM, resulting in BM
. The BM
was successfully adapted for a magnetic SAC, a technique with potential applications in high-throughput protein production and purification.
The SAC protocol can be adapted as a universal tool for the purification of recombinant proteins. Furthermore, the SAC protocol utilizes simple and low-cost reagents, making it suitable for in-house protein purification systems in laboratories worldwide. This enables the production of pure recombinant proteins for research, diagnosis, and the food industry.
A field campaign was conducted October 30th to November 13th, 2015 with the intention of capturing diurnal soil freeze/thaw state at multiple scales using ground measurements and remote sensing ...measurements. On four of the five sampling days, we observed a significant difference between morning (frozen scenario) and afternoon (thawed scenario) ground-based measurements of the soil relative permittivity. These results were supported by an in situ soil moisture and temperature network (installed at the scale of a spaceborne passive microwave pixel) which indicated surface soil temperatures fell below 0 °C for the same four sampling dates. Ground-based radiometers appeared to be highly sensitive to F/T conditions of the very surface of the soil and indicated normalized polarization index (NPR) values that were below the defined freezing values during the morning sampling period on all sampling dates. The Scanning L-band Active Passive (SLAP) instrumentation, flown over the study region, showed very good agreement with the ground-based radiometers, with freezing states observed on all four days that the airborne observations covered the fields with ground-based radiometers. The Soil Moisture Active Passive (SMAP) satellite had morning overpasses on three of the sampling days, and indicated frozen conditions on two of those days. It was found that >60% of the in situ network had to indicate surface temperatures below 0 °C before SMAP indicated freezing conditions. This was also true of the SLAP radiometer measurements. The SMAP, SLAP and ground-based radiometer measurements all indicated freezing conditions when soil temperature sensors installed at 5 cm depth were not frozen.
•Field campaign for capturing diurnal soil freeze/thaw state•Ground-based radiometers were highly sensitive to near surface freezing conditions.•Airborne measurements showed agreement with ground measurements.•Airborne and SMAP indicated freezing when >60% of pixel was frozen.•All remote sensing measurements indicated frozen state when soil unfrozen at 5 cm.
A Type II SLAP (superior labrum anterior posterior) lesion is a tear of the superior glenoid labrum with involvement of the long head of the biceps tendon insertion. In patients that do not improve ...with conservative treatment, there is a great deal of variability in the surgical management of these injuries that includes arthroscopic SLAP repair, arthroscopic SLAP repair with biceps tenodesis, biceps tenodesis alone and biceps tenotomy. Each surgical technique has specific effects on a patient's postoperative course and functional recovery. Rehabilitation strategies may be best formulated on an individual basis with an open line of communication between the operating surgeon and the physical therapist. Despite an increased incidence in treatment, there is currently no consensus on the optimal surgical procedure or treatment algorithm for Type II SLAP injuries. However, in middle-aged or older patients (>35) with Type II SLAP tears, either arthroscopic suprapectoral or mini-open subpectoral biceps tenodesis is recommended due to the higher failure rates observed with arthroscopic SLAP repair in this patient group. Although more patients present with a 'Popeye' sign after biceps tenotomy, long-term functional outcome is similar between biceps tenodesis compared to tenotomy. However, more patients will experience biceps fatigue or cramping after the tenotomy procedure. Biceps tenodesis is preferred in younger, more active patients, while tenotomy is preferred in the middle-aged or older and lower demand patients. The aim of this paper is to provide a brief description of the different surgical techniques employed to address Type II SLAP lesions (arthroscopic repair, biceps tenodesis, and biceps tenotomy) and provide a review of available literature regarding outcomes and prognostic factors associated with each technique.
Background:
The published return-to-play (RTP) rates for athletes who have undergone surgical repair of superior labrum anterior-posterior (SLAP) tears vary widely and are generally accepted to be ...lower in the subset of competitive throwers. The efficacy of nonsurgical treatment for this group is unknown.
Hypothesis:
Nonsurgical treatment of SLAP tears in professional baseball players leads to RTP before consideration of surgical treatment. Incorporating performance statistics and level of competition will result in lower calculated RTP rates than have been previously reported.
Study Design:
Case series; Level of evidence, 4.
Methods:
A retrospective review of 119 consecutive patients in a single professional baseball organization with persistent shoulder pain that limited the ability to compete was performed. Sixty-eight patients had magnetic resonance imaging–documented SLAP lesions. All patients had failed 1 attempt at rehabilitation but had continued with supervised physical therapy. Treatment was according to an algorithm focusing on the correction of scapular dyskinesia and posterior capsular contracture with glenohumeral internal rotation deficit (GIRD), followed by pain-free return to throwing. Those who failed 2 cycles of nonsurgical treatment were treated surgically. Success was defined by 2 different standards: (1) RTP, in accordance with previous studies; and (2) a more stringent standard of return to the same level/quality of professional competition (A, AA, AAA, etc) with the incorporation of a return to preinjury individual performance statistics (earned run average, walks plus hits per inning pitched), termed “return to prior performance” (RPP).
Results:
Sixty-eight athletes were identified with SLAP lesions. Twenty-one pitchers successfully completed the nonsurgical algorithm and attempted a return. Their RTP rate was 40%, and their RPP rate was 22%. The RTP rate for 27 pitchers who underwent 30 procedures was 48%, and the RPP rate was 7%. For 10 position players treated nonsurgically, the RTP rate was 39%, and the RPP rate was 26%. The RTP rate for 13 position players who underwent 15 procedures was 85%, with an RPP rate of 54%.
Conclusion:
Nonsurgical treatment correcting scapular dyskinesia and GIRD had a reasonable success rate in professional baseball players with painful shoulders and documented SLAP lesions. The rate of return after surgical treatment of SLAP lesions was low for pitchers. The RTP and RPP rates were higher for position players than for pitchers. Nonsurgical treatment should be considered for professional baseball players with documented SLAP lesions, as it can lead to acceptable RTP and RPP rates.
Background:
Few studies have documented the outcomes of superior labral anterior-posterior (SLAP) repairs in baseball players. Furthermore, the results of these previous studies varied widely and ...were based on small numbers of patients.
Hypothesis/Purpose:
The purpose was to report return-to-play (RTP) rates and validated subjective outcome scores for baseball players after SLAP repair. It was hypothesized that RTP rates and outcomes would be significantly different between pitchers and nonpitchers, as well as among baseball levels.
Study Design:
Case series; Level of evidence, 4.
Methods:
A series of 216 baseball players was identified who had isolated SLAP repair or SLAP repair with debridement of partial-thickness (<25%) rotator cuff tear at our surgical centers. Patients were contacted by phone a minimum of 2 years after surgery and asked questions about their ability to RTP. Patients were also asked questions to complete the Western Ontario Shoulder Instability Index (WOSI), Veteran’s RAND 12-Item Health Survey (VR-12), and Kerlan-Jobe Orthopaedic Clinic (KJOC) questionnaires. Statistical equivalence in RTP rate, VR-12, and WOSI scores was determined between players with and without concomitant rotator cuff debridement using 2 one-sided tests and risk difference measures. Differences in RTP were tested among baseball levels (high school, college, professional) and positions (pitcher vs nonpitcher) using chi-square analyses (P < .05). Differences in outcomes scores were compared using t tests and analyses of variance (P < .05).
Results:
Of the 216 baseball players, 133 were reached by phone for follow-up interview (mean, 78 months; range, 27-146 months). Overall, 62% successfully returned to play. There were no differences in RTP rates or subjective outcomes among baseball levels or between procedures. RTP rates were 59% for pitchers and 76% for nonpitchers (P = .060). Subjectively, the percentage of patients who felt the same or better at follow-up compared to preinjury was significantly higher among nonpitchers (66%) than pitchers (43%). There was no difference in KJOC scores between the pitchers (75.3 ± 19.4) and nonpitchers (76.2 ± 17.4) who successfully returned to play, although these scores were well below the minimum desired score of 90 for healthy baseball players.
Conclusion:
SLAP repair should continue to be considered as an option for SLAP tear treatment only after nonsurgical management has failed. Some players may be able to return to baseball after SLAP repair, although regaining preinjury health and performance is challenging.
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