bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Race/Ethnicity and Quality-of-Life Policing on Public Attitudes Toward Racially Biased Policing and Traffic Stops
Authors: Zhao Jihong Solomon , Lai Yung-Lien , Ren Ling , Lawton Brian
Published: February 2011

This article examines the impact of race/ethnicity and quality-of-life (QOL) policing on citizens’ perceptions of racial bias and traffic stops. Using data obtained from a random-sample telephone survey of Houston citizens, respondents were asked whether they felt that the police treated citizens “equally” based on the race/ethnicity of the citizen as well as the race/ethnicity of the officer. These variables were then recoded to construct a nominal measure ranging from racially biased policing to absence of racially biased policing, with a middle category of “semiracially” biased policing. Results indicated that race/ethnicity was a significant predictor. In addition, the results strongly suggested that QOL policing was significantly associated with a decrease in respondents’ perceptions of racially biased policing. Finally, there was a significant relationship between racially biased policing and expected treatment of traffic stops made by the police.
Examining the Effects of Residential Situations and Residential Mobility on Offender Recidivism
Authors: Steiner Benjamin , Makarios Matthew D. , Travis Lawrence F.
Published: February 2011

Drawing from theories of social control, this study involved an examination of the time-varying effects of six different residential situations and residential mobility on offenders’ odds of recidivism during the year immediately following their release from prison. Analyses of data collected on a statewide sample of offenders released under supervision in Ohio generated results favoring a control perspective. Both residential mobility and residential situations such as living with a spouse or parent were relevant for understanding differences among offenders in their odds of recidivism. Stable characteristics of offenders such as gender and prior criminal history were also linked to recidivism.
On the vibration and stability of clamped FGM conical shells under external loads
Authors: Sofiyev A.H.
Published: February 2011

An analytical formulation is presented for vibration and buckling analyses of clamped conical shells made of functionally graded materials (FGMs) under various uniform pressures. It is assumed that the shell is a metal and ceramic mixture and its properties change as a function of the shell thickness. In this study, both types of FGM, power and exponential, are taken into account together. The governing equations according to the Donnell’s theory are solved by Galerkin’s method and the critical hydrostatic and lateral pressures and fundamental frequencies have been found analytically. To solve this problem, an unknown parameter λ is included in the approximation functions. Furthermore, parameter λ, which is included in the obtained formulas, is taken from the minimum conditions of critical stresses and frequencies. The different generalized values are obtained for the parameter λ for buckling pressures and frequencies of cylindrical shells, and truncated and complete conical shells with clamped edges. Several examples are presented to show the accuracy and efficiency of the formulation. The closed-form solutions are verified by accurate different solutions. Effects of changing radius-to-thickness ratio, lengths-to-radius ratio, material composition, and volume fraction of constituent materials on the critical parameters of truncated and complete conical shells are also investigated.
Simulation and experimental validation of force controlled compression resin transfer molding
Authors: Verleye B. , Walbran W.A. , Bickerton S. , Kelly P.A.
Published: February 2011

The simulation of composite manufacturing processes is a great aid to obtaining efficient production and high-quality parts. The mold and process design must allow for fast filling times as well as dry-spot free parts. Besides an accurate simulation of the resin flow through the reinforcement, the compaction response of the preform is also needed. The stress response of the textile to compaction has an influence on the local and global forces exerted on tooling. The numerical prediction of the clamping force helps to trade-off fast production times against affordable machinery. This article describes the accurate simulation of force controlled Resin Transfer Molding (RTM) and Compression RTM, and compares results of simulations with experimental data. A parametric study is performed in order to minimize the simulation time without compromising the accuracy of the results. The controlled force algorithms have been implemented within SimLCM, a code under development at the University of Auckland to address the liquid composite molding (LCM) family of manufacturing processes. With these new tools, the trade-off between production process time and equipment cost can be considered, and optimal process design solutions found.
Differentiation of Dental Pulp Stem Cells into Islet-like Aggregates
Authors: Govindasamy V. , Ronald V.S. , Abdullah A.N. , Nathan K.R. Ganesan , Ab. Aziz Z.A.C. , Abdullah M. , Musa S. , Kasim N.H. Abu , Bhonde R.R
Published: February 2011

The post-natal dental pulp tissue contains a population of multipotent mesenchymal progenitor cells known as dental pulp stromal/stem cells (DPSCs), with high proliferative potential for self-renewal. In this investigation, we explored the potential of DPSCs to differentiate into pancreatic cell lineage resembling islet-like cell aggregates (ICAs). We isolated, propagated, and characterized DPSCs and demonstrated that these could be differentiated into adipogenic, chondrogenic, and osteogenic lineage upon exposure to an appropriate cocktail of differentiating agents. Using a three-step protocol reported previously by our group, we succeeded in obtaining ICAs from DPSCs. The identity of ICAs was confirmed as islets by dithiozone-positive staining, as well as by expression of C-peptide, Pdx-1, Pax4, Pax6, Ngn3, and Isl-1. There were several-fold up-regulations of these transcription factors proportional to days of differentiation as compared with undifferentiated DPSCs. Day 10 ICAs released insulin and C-peptide in a glucose-dependent manner, exhibiting in vitro functionality. Our results demonstrated for the first time that DPSCs could be differentiated into pancreatic cell lineage and offer an unconventional and non-controversial source of human tissue that could be used for autologous stem cell therapy in diabetes.
The Role of Lipopolysaccharide on the Electrochemical Behavior of Titanium
Authors: Barão V.A. , Mathew M.T. , Assunção W.G. , Yuan J.C. , Wimmer M.A. , Sukotjo C.
Published: February 2011

Lipopolysaccharide (LPS) may induce peri-implantitis and implant failure. However, the role of LPS in titanium (Ti) electrochemical behavior remains unknown. We hypothesized that LPS in saliva with different pHs affects Ti corrosion properties. Thirty-six Ti discs (15 mm × 3 mm) were divided into 12 groups according to saliva pH (3, 6.5, and 9) and Escherichia coli LPS concentration (0, 0.15, 15, and 150 µg/mL). Electrochemical tests, such as open circuit potential, potentiodynamic, and electrochemical impedance spectroscopy, were conducted in a controlled environment. Data were evaluated by Pearson correlation and regression analysis (α = 0.05). LPS and pH affected Ti corrosive behavior. In general, lower pH and higher LPS concentration accelerated Ti corrosion. In the control group, the increase of pH significantly reduced the corrosion rate and increased the capacitance of the double layer. In LPS groups, the decrease of pH significantly increased the corrosion rate of Ti. LPS negatively influenced Ti corrosion behavior. Abbreviations: Cdl, capacitance of double layer; Ecorr, corrosion potential; EIS, electrochemical impedance spectroscopy; Icorr, corrosion current density; Ipass, passivation current density; LPS, lipopolysaccharide; OCP, open circuit potential; Rp, polarization resistance; Ti, titanium.
Self-etch Monomer-Calcium Salt Deposition on Dentin
Authors: Yoshihara K. , Yoshida Y. , Hayakawa S. , Nagaoka N. , Torii Y. , Osaka A. , Suzuki K. , Minagi S. , Van Meerbeek B. , Van Landuyt K.L.
Published: February 2011

Previous research, in which the bonding effectiveness of the 3 self-etch monomers HAEPA, EAEPA, and MAEPA was determined, showed that MAEPA was most effective. In this study, the molecular interactions of these monomers with hydroxyapatite and dentin were investigated by combining x-ray diffraction, infrared spectroscopy, and scanning electron microscopy. We tested the null hypothesis that the bonding performance of these monomers does not correlate to the formation of monomer-calcium salts and to hydrolytic stability of these monomer-calcium complexes. Monomer/ethanol/water solutions were prepared and applied to synthetic hydroxyapatite and dentin. While HAEPA and EAEPA dissolved dentin considerably and deposited unstable calcium-phosphate salts (DCPD), MAEPA formed hydrolysis-resistant monomer-calcium salts that remained attached to the dentin surface even after being washed. The chemical stability of the monomer-Ca salts was thought to contribute in particular to the bond durability, but this study shows that the formation of stable monomer-calcium salts also enhances the ‘immediate’ bonding performance of self-etch adhesives.
Effects of Chlorhexidine and Fluoride on Irradiated Enamel and Dentin
Authors: Soares C.J. , Neiva N.A. , Soares P.B.F. , Dechichi P. , Novais V.R. , Naves L.Z. , Marques M.R.
Published: February 2011

The effectiveness of mouthwash protocols in preventing gamma irradiation therapy damage to the ultimate tensile strength (UTS) of enamel and dentin is unknown. It was hypothesized that the use of chlorhexidine and fluoride mouthwash would maintain the UTS of dental structures. One hundred and twenty teeth were divided into 2 groups: irradiated (subjected to 60 Gy of gamma irradiation in daily increments of 2 Gy) and non-irradiated. They were then subdivided into 2 mouthwash protocols used 3 times per day: 0.12% chlorhexidine, 0.05% sodium fluoride, and control group (n = 10). The specimens were evaluated by microtensile testing. The results of the Tukey test ( p < 0.05) indicated that the gamma irradiation therapy significantly reduced the UTS of the enamel, crown, and root dentin. Macromolecular alterations were suggested by optical retardation data in dentin. Structural alterations, in both substrates, were detected by scanning electron microscopy analysis. Mouthwash with 0.12% chlorhexidine partially prevented the damage to the mechanical properties of the irradiated crown dentin, whereas the 0.05% sodium-fluoride-irradiated enamel showed UTS similar to that of non-irradiated enamel.
Epilogue: Theoretical and Comparative Notes on Reserve Forces
Authors: Ben-Ari Eyal , Lomsky-Feder Edna
Published: February 2011

This concluding epilogue places the individual studies presented in the special volume in wider perspective. The importance of studying reserve forces centers on (1) their centrality in missions carried out by the militaries of the contemporary industrial democracies and (2) their unique cultural and organizational characteristics. Concretely, reserve components are a foundation for the legitimacy of the military, yet are often a source for criticism of missions; they provide a ready pool of manpower but one that is sometimes expensive; their skills are sometimes needed but their military abilities do not always meet the perceived standards of standing forces’ professionals. Research into this military group that is situated between the military and civil society clarifies not only the interlinkages between these spheres but also their dynamic and contextual nature.
Diagnostic Accuracy of Nasopharyngeal Swabs in Detecting Biofilm‐Producing Bacteria in Chronic Adenoiditis
Authors: Torretta Sara , Drago Lorenzo , Marchisio Paola , Mattina Roberto , Clemente Ignazio Alessandro , Pignataro Lorenzo
Published: February 2011

Objectives

Biofilms are organized bacterial communities that are playing an increasing role in otolaryngological diseases such as chronic or recurrent middle ear otitis and adenotonsillitis. Various cultural techniques are available to detect biofilm‐producing bacteria (BPB), but microbiological analysis of bioptic staining is the reference diagnostic procedure. To our knowledge, the accuracy of nasopharyngeal swabs in diagnosing BPB has never been assessed.

Study Design

A prospective study of diagnostic accuracy.

Setting

Outpatient clinics of the Departments of Specialist Surgical Sciences and Maternal and Pediatric Sciences, University of Milan, Italy.

Subjects and Methods

Forty‐two pediatric subjects with chronic adenoiditis (aged 4‐18 years) underwent adenoidectomy, during which multiple transoral nasopharyngeal swabs and adenoidal biopsies were performed. BPB were detected by spectrophotometry, and the accuracy of detecting BPB in nasopharyngeal swabs was compared with that of biopsy.

Results

BPB were detected in 73.8% of the nasopharyngeal swabs and in 69.1% of the biopsies. The sensitivity and specificity of the nasopharyngeal swabs were, respectively, 75.9% (95% confidence interval [CI], 60.3%‐91.4%) and 30.8% (95% CI, 5.7%‐55.9%); positive and negative predictive values were, respectively, 71.0% (95% CI, 55.0%‐86.9%) and 36.4% (95% CI, 7.9%‐64.8%); and the area under the receiver‐operating characteristic curve was 0.5 (95% CI, 0.4‐0.7).

Conclusions

In comparison with biopsy, nasopharyngeal swabs seem to be inaccurate in detecting BPB and should be cautiously used in clinical practice. As these preliminary findings may have been due to the well‐known resistance of biofilm to mechanical injuries (such as swab rubbing) or the small study population, they need to be confirmed in larger patient series.
Preoperative Parathyroid Hormone Levels as a Predictor of Postthyroidectomy Hypocalcemia
Authors: Sands Noah , Young Jonathan , MacNamara Elizabeth , Black Martin J. , Tamilia Michael , Hier Michael P. , Payne Richard J.
Published: February 2011

Objectives

The goal of the present study is to determine whether a decline in the 1‐hour postoperative parathyroid hormone (PTH) level relative to the preoperative level is predictive of hypocalcemia.

Methods

This is a retrospective study involving 142 consecutive patients who underwent total thyroidectomy. Changes in preoperative PTH levels were then compared with the 1‐hour levels.

Results

Thirty‐four of 142 patients (23.9%) who underwent total thyroidectomy developed hypocalcemia. Thirty‐one of the 34 patients who became hypocalcemic had a 1‐hour postoperative PTH drop of 70% or more when compared with the preoperative value (sensitivity = 91%, specificity = 98%, positive predictive value = 94%, and negative predictive value = 97%).

Conclusion

A decline in the preoperative PTH level of 70% or greater at 1 hour following total thyroidectomy appears to be a reliable predictor of patients at risk of developing hypocalcemia. By allowing thyroid surgeons to identify these patients in the early postoperative period, calcium supplementation can be initiated sooner.
Malignant External Otitis
Authors: Soudry Ethan , Hamzany Yaniv , Preis Michal , Joshua Benzion , Hadar Tuvia , Nageris Ben I.
Published: February 2011

Objective

To study the effect of specific clinical, laboratory, and imaging parameters on the course of severe (type 1) malignant external otitis (MEO).

Study Design

Case series with chart review.

Setting

Tertiary, university‐affiliated medical center.

Subjects and Methods

Fifty‐seven patients hospitalized with severe MEO were followed for disease course and survival in a tertiary center between 1990 and 2008.

Results

In 20% of patients, disease was persistent and/or aggressive despite prolonged and extensive treatment. Of this subgroup, 45% died of the disease. Prognostic factors of persistent/aggressive disease were facial nerve paralysis, bilateral disease, and significant major computed tomography findings (temporomandibular joint destruction, infratemporal fossa or nasopharyngeal soft tissue involvement). Cultures grew fungi in 5 patients, and follow‐up imaging revealed disease progression. The overall 5‐year survival was 55% for patients with short‐term disease and 40% for patients with persistent/ aggressive disease (P =. 086). By age, 5‐year survival was 75% in patients younger than 70 years old and 44% in older patients (P =. 029).

Conclusions

A significant subset of patients with MEO has a prolonged, aggressive, and highly fatal disease that needs to be identified early. These patients more frequently have bilateral disease, cranial nerve paralysis, and positive computed tomography findings. Their follow‐up should routinely include imaging studies to evaluate disease progression, and every effort should be made to identify and treat underlying fungal infection.
Otolaryngology Resident Workflow
Authors: Victores Andrew , Roberts Jess , Sturm‐O’Brien Angela , Victores Nina , Uecker Wil , Alford Bobby , Takashima Mas
Published: February 2011

Objective

To investigate workflow in an otolaryngology–head and neck surgery residency program over 1 year and identify areas for improvement in the efficiency of resident education and training.

Study Design

Time‐motion study.

Setting

An urban, county hospital and a Veterans Affairs medical center hospital.

Subjects and Methods

Eight otolaryngology residents (4 residents at postgraduate year [PGY] 2 and 4 at PGY 4) were studied using direct observations early and late in the 2008‐2009 academic year. Resident activities were categorized, and a database program was generated for a handheld computer to facilitate time entry. Resident activities were classified into a taxonomy of tasks and their educational value was assessed. For each PGY level studied, observations were made for clinic and operative days.

Results

Residents spent their day on direct patient care (43.5%), indirect patient care (33.7%), didactic education (9.6%), personal activities (7.5%), and transit (5.8%), with activities of marginal educational value consuming 16% of their time. Major inefficiencies included managing administrative tasks, scheduling, and technical difficulties. On average, residents devoted significantly more time to marginal tasks on clinic days (19%) than on operative days (12%; P <. 001). These data were compared with previously published data obtained during the pre–Accreditation Council for Graduate Medical Education (ACGME) duty hour mandates era.

Conclusion

This study evaluates resident workflow and efficiency over the course of a PGY in an ACGME‐accredited otolaryngology residency program. By understanding the time motion of residents, interruptions and inefficiencies in workflow can be identified to direct future changes to enhance resident education and training in the era of the ACGME duty hours mandate.
Cellular Adaptive Inflammation Mediates Airway Granulation in a Murine Model of Subglottic Stenosis
Authors: Ghosh Ankona , Malaisrie Nora , Leahy Kevin P. , Singhal Sunil , Einhorn Eugene , Howlett Paul , Cohen Noam A. , Mirza Natasha
Published: February 2011

Objective

To determine the contribution of B‐ and T‐cell–mediated inflammation in a murine airway granulation model.

Study Design

Pilot study in a modified murine model.

Setting

Philadelphia VA Medical Center Research Building.

Subjects and Methods

Laryngotracheal complexes (LTCs) from 54 donor C57BL/6 mice were harvested and divided into 3 groups: (1) uninjured, (2) mechanically injured using a wire brush, and (3) chemically injured using hydrochloric acid. One donor LTC from each group was placed in deep dorsal subcutaneous pockets of either severe combined immunodeficiency (SCID)– or C57BL‐recipient mice, for a total of 3 transplanted tracheas per recipient mouse. After 3 weeks, the transplanted LTCs were harvested from both C57BL‐ and SCID‐recipient mice. Tissues were fixed, sectioned, and stained with hematoxylin and eosin. Representative slides were reviewed by a blinded pathologist to determine the formation of granulation tissue and graded as to the degree of formation of granulation tissue.

Results

Despite significant granulation formation in C57BL‐recipient mice, direct airway injury did not induce the formation of granulation tissue under the disrupted epithelium of airway mucosa in SCID mice 3 weeks after injury.

Conclusion

The data indicate that the immune response that results in the formation of granulation tissue is mediated by circulating B‐ and/or T‐cell processes rather than resident airway immune cells. Further studies focusing on cellular adaptive immune processes in response to airway injury may provide a novel treatment modality for subglottic stenosis.
Interdisciplinary Treatment for Vestibular Dysfunction
Authors: Naber Christine M. , Water‐Schmeder Omay , Bohrer Pamela S. , Matonak Kathy , Bernstein Allan L. , Merchant Maqdooda A.
Published: February 2011

Objective

To investigate whether an interdisciplinary program for vestibular patients improved health outcomes and health care utilization.

Study Design

Case series with chart review.

Setting

Outpatient neurotology clinic.

Subjects and Methods

Patients (N = 167) with dizziness attended an interdisciplinary neurotology clinic; 129 were offered group treatment. After an introductory session, group treatment included 5 sessions incorporating mindfulness, cognitive‐behavioral techniques, and vestibular rehabilitation. Physical and emotional functioning, depression, anxiety, dizziness, impairment, coping, skill use, and patient satisfaction were measured with rating scales pre‐ and postgroup treatment. Data from 51 patients (male/female = 14/37; age range, 25‐82 years) were analyzed with paired t tests or nonparametric tests. Logistic regression analyzed predictors of outcome and utilization for 116 patients (male/female = 81/35; age range, 11‐86 years) attending the interdisciplinary clinic, introductory session, and/or group.

Results

After group treatment, patients reported better mood (P =. 0482); better physical (P =. 0006) and mental (P =. 0183) health; better functionality, coping, and skill use (Ps <. 0001); less impairment (P <. 0001); and fewer limitations from dizziness (P <. 0001). Higher pretreatment levels of depression (P =. 0216), poorer initial mental (P =. 0164) or physical (P =. 0059) health, and peripheral diagnosis (P =. 0220) predicted better outcome. Group treatment decreased utilization more than the interdisciplinary clinic with (P =. 0183) or without (P =. 0196) the introductory session; 78% of patients with any level of participation showed less utilization. Clinic patients had fewer radiology procedures than group patients (P =. 0365). Patients were highly satisfied with the program and found it more effective than previous treatment.

Conclusion

Interdisciplinary treatment improves patient coping, functionality, and satisfaction and decreases overall health care utilization in vestibular patients.
Ossicular Chain Reconstruction Using Titanium versus Hydroxyapatite Implants
Authors: Gelfand Yuri M. , Chang C. Y. Joseph
Published: February 2011

Objectives

Compare the efficacy of total and partial ossicular chain reconstruction using hydroxyapatite (HA) implants versus titanium (Ti) implants.

Design

Case series with chart review.

Setting

Academic tertiary referral center and private practice.

Subjects and Methods

404 patients underwent ossiculoplasty using either Ti or HA implants from June 1996 to September 2008. Patient data were collected retrospectively from the senior author’s electronic database of surgical cases.

Results

The change in air–bone gap (ΔABG) (defined as the difference between the means of preoperative and postoperative ABG) was 9.9 dB for the HA group that received partial ossicular reconstruction prosthesis (PORP), 9.5 dB for the Ti PORP group, 12.3 dB for the Ti group that received total ossicular reconstruction prosthesis (TORP), and 10.0 dB for the HA TORP group. There was no statistically significant difference between the HA and Ti groups. There was no significant difference in hearing results between canal wall up (CWU) and canal wall down (CWD) cases in which mastoidectomy was performed. Four confounding factors (preoperative otorrhea, preoperative perforation, cholesteatoma, mastoidectomy performed) were analyzed using regression analysis. In the Ti PORP group, the presence of cholesteatoma was found to have a significant negative bias for hearing results.

Conclusion

No statistically significant differences in hearing results were found between the HA and the Ti partial and total ossiculoplasty prostheses. No outcome difference was found between CWU versus CWD mastoidectomy groups for any type of implant used. A randomized, prospective study is necessary for a more definitive comparison of efficacy between HA and Ti OCR implants.
Preliminary Findings on the Effects of Topical Photoactivated Antimicrobial Methyl‐δ‐Aminolevulinic Acid on Murine Hearing Thresholds
Authors: Roehm Corrie E. , Valdez Tulio A. , Parham Kourosh
Published: February 2011

This study evaluates the ototoxicity of a potential novel ototopical antimicrobial, photoactivated methyl‐δ‐aminolevulinic acid (M‐ALA). Ten CBA/J mice received intratympanic injections of 10 mM M‐ALA and 640 nm light source illumination for 7 days, with contralateral ears receiving saline. Auditory‐evoked brainstem response (ABR) thresholds (8, 16, 24, and 32 kHz) were determined preinjection and at 1, 30, and 90 days postinjection. Mean ABR thresholds were similar after intratympanic administration of M‐ALA and saline (F ratio, 0.001; P =. 971). ABR thresholds temporarily increased in both groups (F ratio, 28.52; P =. 00) at day 1 postinjection of intratympanic treatments but returned to baseline at day 30 and 90. This temporary elevation was associated with tympanic membrane perforations and granulation tissue at the injection sites, which resolved by day 30 posttreatment. The preliminary findings indicate that intratympanic application of M‐ALA with light activation over a 7‐day course in a murine model does not produce measurable ototoxicity and is well tolerated.
The impact of contracts on trust in entrepreneur–venture capitalist relationships
Authors: Strätling Rebecca , Wijbenga Frits H. , Dietz Graham
Published: February 2011

Venture capitalists (VCs) increasingly rely on elaborate formal contracts and incentivization through share ownership to manage their relationships with the entrepreneurial firms in which they invest. This study analyses the impact of a high degree of such ‘neoclassical contracting’ on entrepreneurs’ trust in their VC backers. The results from a sample of 86 Dutch entrepreneurial firms indicate not only that a high degree of neoclassical contracting tends to erode entrepreneurs’ trust in their VCs, but also that the use of more informal, relational contracting fails to moderate the negative association between a strong focus on neoclassical contracts and trust. However, entrepreneurs do welcome some level of monitoring, which highlights the enduring tension between trust and control, and the need for VCs to strike a productive balance.
Gender Differences in Monitoring and Deviant Peers as Predictors of Delinquent Behavior Among Low-Income Urban African American Youth
Authors: O’Donnell Philip , Richards Maryse , Pearce Steven , Romero Edna
Published: February 2011

Juvenile delinquency is an ongoing social problem particularly among low-income urban youth who are regularly exposed to numerous risk factors. Although much research has been conducted in this area, the most at-risk youth have been largely neglected. This study examines the role of peer deviance in mediating the influence of adult monitoring on male and female adolescents’ delinquent behavior, using multisource, multimethod data with an emphasis on differing impacts across the two genders. Results suggest that the level of peer deviance partially mediates the impact of monitoring on delinquent behavior, even after controlling for previous levels of delinquency. However, girls’ delinquency appear to be more influenced by peers than their perceptions of monitoring. Conversely, boys’ delinquent behavior is associated with daily immediate monitoring, not peer behaviors. These results are discussed in the context of particular issues facing low-income urban African American families.
Generalizing foraging theory for analysis and design
Authors: Pavlic Theodore P , Passino Kevin M
Published: February 2011

Foraging theory has been the inspiration for several decision-making algorithms for task-processing agents facing random environments. As nature selects for foraging behaviors that maximize lifetime calorie gain or minimize starvation probability, engineering designs are favored that maximize returned value (e.g. profit) or minimize the probability of not reaching performance targets. Prior foraging-inspired designs are direct applications of classical optimal foraging theory (OFT). Here, we describe a generalized optimization framework that encompasses the classical OFT model, a popular competitor, and several new models introduced here that are better suited for some task-processing applications in engineering. These new models merge features of rate maximization, efficiency maximization, and risk-sensitive foraging while not sacrificing the intuitive character of classical OFT. However, the central contributions of this paper are analytical and graphical methods for designing decision-making algorithms guaranteed to be optimal within the framework. Thus, we provide a general modeling framework for solitary agent behavior, several new and classic examples that apply to it, and generic methods for design and analysis of optimal task-processing behaviors that fit within the framework. Our results extend the key mathematical features of optimal foraging theory to a wide range of other optimization objectives in biological, anthropological, and technological contexts.
A stochastic kinematic model of class averaging in single-particle electron microscopy
Authors: Park Wooram , Midgett Charles R , Madden Dean R , Chirikjian Gregory S
Published: February 2011

Single-particle electron microscopy is an experimental technique that is used to determine the three-dimensional (3D) structure of biological macromolecules and the complexes that they form. In general, image processing techniques and reconstruction algorithms are applied to micrographs, which are 2D images taken by electron microscopes. Each of these planar images can be thought of as a projection of the macromolecular structure of interest from an a priori unknown direction. A class is defined as a collection of projection images with a high degree of similarity, presumably resulting from taking projections along similar directions. In practice, micrographs are very noisy and those in each class are aligned and averaged in order to reduce the background noise. Errors in the alignment process are inevitable due to noise in the electron micrographs. This error results in blurry averaged images. In this paper, we investigate how blurring parameters are related to the properties of the background noise in the case when the alignment is achieved by matching the mass centers and the principal axes of the experimental images. We observe that the background noise in micrographs can be treated as Gaussian. Using the mean and variance of the background Gaussian noise, we derive equations for the mean and variance of translational and rotational misalignments in the class averaging process. This defines a Gaussian probability density on the Euclidean motion group of the plane. Our formulation is validated by convolving the derived blurring function representing the stochasticity of the image alignments with the underlying noiseless projection and comparing with the original blurry image.
Lesions of the Biceps Pulley
Authors: Braun Sepp , Horan Marilee P. , Elser Florian , Millett Peter J.
Published: February 2011

Background: Lesions of the biceps pulley and instability of the long head of the biceps tendon are common diagnoses in patients with anterior shoulder pain.

Purpose: To analyze the pathoanatomy of the biceps reflection pulley (“pulley”) in consecutive patients undergoing shoulder arthroscopy.

Study Design: Cohort study (prevalence); Level of evidence, 2.

Methods: Prospective data were collected on 229 shoulders in consecutive patients (155 male,74 female) who underwent shoulder arthroscopy (121 rotator cuff pathology, 50 instability, 43 osteoarthritis, 15 miscellaneous). The average age was 48.5 years (range, 18-76 years). Sixty-eight shoulders had underwent a previous surgery.

Results: The long head of the biceps tendon was absent in 21 shoulders (9.2%); 1 was excluded for incomplete data. In 207 shoulders, the mean width of the long head of the biceps tendon was 6.0 mm (range, 3-10 mm), and the pulley complex, 7.2 mm (range, 4-15 mm). Sixty-seven patients (32.4%) had a pulley tear: 48 shoulders had anteromedial pulley tears, 32 posterolateral, with 13 combined anteromedial-posterolateral lesions. Patients with pulley tears were significantly older than those without (57 vs 44 years, P < .001). For anteromedial pulley tears, the mean width of the long head of the biceps tendon was significantly larger in the torn group (6.4 vs 5.8 mm, P = .012). The anteromedial or posterolateral pulley tears were significantly associated with subluxation or dislocation of the long head of the biceps tendon ( P = .001), with a pulley torn in all 27 cases of biceps dislocation. In 173 shoulders with a centered long head of the biceps tendon, the pulley was torn in 36 (23 anteromedial, 18 posterolateral [with 5 being combined]). Pulley tears and rotator cuff injury showed a significant association ( P < .001). Superior labral anterior posterior lesions were significantly associated with anteromedial ( P < .008) and posterolateral pulley tears ( P < .021).

Conclusion: Pulley lesions are fairly common in patients undergoing arthroscopic surgery and were found in 32.4% of this prospective cohort (67 of 207). Current consensus indicates that pulley lesions are often associated with rotator cuff tears. This series also showed correlations with superior labral anterior posterior tears, biceps instability, and long head of the biceps tendon tears.
Comparison of Postural Stability Between Injured and Uninjured Ballet Dancers
Authors: Lin Cheng-Feng , Lee I-Jung , Liao Jung-Hsien , Wu Hong-Wen , Su Fong-Chin
Published: February 2011

Background: Ballet movements require a limited base of support; thus, ballet dancers require a high level of postural control. However, postural stability in ballet dancers is still unclear and needs to be understood.

Purpose: To evaluate ballet dancers’ postural stability in performing single-leg standing, the en pointe task, and the first and fifth positions and to determine differences in task performance among healthy nondancers, healthy dancers, and dancers with ankle sprains.

Study Design: Controlled laboratory study.

Methods: Injured dancers, uninjured dancers, and nondancers were recruited for this study (N = 33 age-matched participants; n= 11 per group). The tasks tested were single-leg standing with eyes open and closed, first position, fifth position, and en pointe. Center of pressure parameters were calculated from the ground-reaction force collected with 1 force plate. Analysis of variance was used to assess the differences of center of pressure parameters among 3 groups in single-leg standing; independent t test was used to examine the differences of center of pressure parameters between injured and uninjured dancers.

Results: During single-leg standing, injured dancers had significantly greater maximum displacement in the medial-lateral direction and total trajectory of center of pressure, compared with the uninjured dancers and nondancers. During the first and fifth positions, the injured dancers demonstrated significantly greater standard deviation of center of pressure position in the medial-lateral and anterior-posterior directions, compared with the uninjured dancers. During en pointe, the injured dancers had significantly greater maximum displacement in the medial-lateral direction and the anterior-posterior direction, compared with the uninjured dancers.

Conclusion: The injured and uninjured dancers demonstrated differences in postural stability in the medial-lateral direction during single-leg standing and the ballet postures. Although the injured dancers received ballet training, their postural stability may still be inferior to that of the nondancers.

Clinical Relevance: This study is a first step in understanding that injured ballet dancers do not have the same postural stability as uninjured dancers and that it is even inferior to that of nondancers, which is important to understand for further study on rehabilitation. The future development of effective balance training programs for ballet dancers with ankle injuries should emphasize improvements in medial-lateral directional balance.
Isolated Tears of the Gracilis Muscle
Authors: Pedret Carles , Balius Ramon , Barceló Pablo , Miguel Maribel , Lluís Anna , Valle Xavier , Gougoulias Nikolaos , Malliaropoulos Nikolaos , Maffulli Nicola
Published: February 2011

Background: Although posterior thigh muscle strains are common in athletes, there are no reports regarding isolated gracilis muscle injuries. The authors present a case series of 7 elite athletes with isolated gracilis muscle ruptures.

Purpose: To present the injury pattern, clinical presentation, diagnosis, and outcome of gracilis muscle ruptures.

Study Design: Case series; Level of evidence, 4.

Methods: This is a retrospective review of 7 elite athletes with posterior thigh pain (3 dancers, 2 soccer players, 1 tae kwon do player, 1 tennis player). In all athletes, the injury occurred during thigh adduction with the hip internally rotated, as clearly evident at ultrasound scans performed 1 to 20 days after the injury. Management included an initial rest period, followed by physiotherapy and gradual return to sports activities.

Results: According to the ultrasound scans, the lesions were in the proximal-middle third junction of the thigh, at the muscle-tendon junction. The lesions were classified as grade 2 (partial discontinuity). The muscle injury area was, on average, 17.1 × 23.7 mm (range, 10-31 × 9-46 mm). The average length of the lesions was 40.14 mm (range, 20-52 mm). All athletes recovered and returned to full performance within 6 weeks of the injury (average, 35.6 days).

Conclusion: Medial thigh pain after eccentric contraction during hip adduction should raise suspicion of a gracilis muscle tear. Ultrasound is useful, and full recovery occurs within 6 weeks from the injury.
Effect of Femoral Socket Position on Graft Impingement After Anterior Cruciate Ligament Reconstruction
Authors: Maak Travis G. , Bedi Asheesh , Raphael Bradley S. , Citak Musa , Suero Eduardo M. , Wickiewicz Thomas , Pearle Andrew D.
Published: February 2011

Background: Despite improved biomechanical stability and kinematics with anatomic anterior cruciate ligament (ACL) reconstruction, concerns regarding notch impingement of the graft have persisted, particularly with increasingly anterior tibial tunnel position. The potentially mitigating effect of anatomic femoral socket position, however, has not been evaluated.

Hypothesis: Placement of the femoral socket in the central or posterolateral bundle footprint reduces the risk and magnitude of graft impingement after ACL reconstruction compared with placement in the anteromedial bundle footprint.

Study Design: Controlled laboratory study.

Methods: This study employed computer-assisted navigation in a cadaveric model to evaluate the effect of tibial and femoral tunnel position on ACL graft impingement. Sixteen cadaveric knees were tested using the Praxim ACL Surgetics Navigation System, with the tibial tunnel positioned in the footprint of the anteromedial bundle and the femoral socket placed in the (1) anteromedial bundle footprint, (2) center of footprint, or (3) posterolateral bundle footprint. The amount of maximum impingement, angle of initial impingement, and location of graft impingement were documented through a full arc of knee motion.

Results: Impingement occurred with all 3 femoral socket positions, but the mean angle of impingement with the anteromedial femoral position (42.8° ± 26.4°) was significantly greater ( P < .003) than the mean angles of impingement with the central femoral position (19.4° ± 19.2°) and the posterolateral bundle femoral position (16.7° ± 13.3°).

Conclusion: Although notch impingement was seen in all femoral socket locations with an anteromedial tibial socket position, femoral socket position in a central or posterolateral bundle location may reduce the risk and magnitude of graft impingement after ACL reconstruction. Additional studies are necessary to determine the influence of these different constructs on graft isometry and knee kinematics.

Clinical Relevance: Anatomic femoral socket position in the center of the native ACL footprint may reduce the risk and magnitude of notch impingement compared with an anteromedial bundle position with ACL reconstruction.
Can Anatomic Femoral Tunnel Placement Be Achieved Using a Transtibial Technique for Hamstring Anterior Cruciate Ligament Reconstruction?
Authors: Strauss Eric J. , Barker Joseph U. , McGill Kevin , Cole Brian J. , Bach Bernard R. , Verma Nikhil N.
Published: February 2011

Background: Recent studies have emphasized the importance of anatomic tunnel placement during anterior cruciate ligament (ACL) reconstruction in an effort to restore normal knee kinematics and stability. Secondary to the constraints imposed by a coupled drilling technique, the ability to achieve an anatomic femoral tunnel during transtibial hamstring ACL reconstruction may be limited.

Hypothesis: The size limitations imposed by the small-diameter tibial tunnel used in hamstring ACL reconstruction would preclude the ability to place an anatomic femoral tunnel.

Study Design: Descriptive laboratory study.

Methods: In a descriptive laboratory study, fresh-frozen human cadaveric knees fixed at 90° of flexion were dissected to expose the centers of the native femoral and tibial ACL insertions. The geometry and location of each insertion were evaluated. Using a standardized starting point, tibial tunnels were drilled to the center of the tibial insertion using an 8-mm reamer. Next, a 6-mm over-the-top guide was used to position as close as possible to the anatomic femoral ACL insertion on the lateral wall, and femoral tunnels were drilled with the 8-mm reamer. For each tunnel, the location, geometry, and percentage overlap with the native insertion site were evaluated using a 3-dimensional laser scanner.

Results: The reamed tibial tunnel was central within the insertion site, occupying 40.4% ± 2.0% of the native tibial insertion. Transtibial drilling resulted in femoral tunnels that were superior and posterior compared with the native femoral insertion. Thefemoral tunnel had a mean ± SD overlap of 30.0% ± 12.6% with the femoral insertion, with the center of the tunnel 7.6± 0.5 mm from the center of the native ACL femoral insertion.

Conclusion: Based on our data using our specific starting point, during hamstring ACL reconstructions, the constraints imposed by a coupled drilling technique result in nonanatomic femoral tunnels that are superior and posterior to the native femoral insertion.

Clinical Relevance: Anatomic femoral tunnel placement during hamstring ACL reconstructions may not be possible using a coupled, transtibial drilling approach.
Reduced Chondrocyte Viability Is Associated With the Use of Surgical Marker Pen Ink
Authors: Getgood Alan , McNamara Iain , Kili Sven , Bhullar Tony , Henson Frances
Published: February 2011

Background: Sterile surgical marker pens are commonly used in cartilage repair surgery to aid in the placement of periosteal patches or collagen membranes in autologous chondrocyte implantation.

Purpose: To investigate the effects that methylene blue and crystal violet marker pen ink have on human chondrocytes when cultured on collagen membranes in vitro.

Study Design: Controlled laboratory study.

Methods: Human chondrocytes were applied to Chondro-Gide collagen membranes at a volume of 12 million cells. In the first experiment, 2 sterile marker pens, one containing methylene blue and the other crystal violet inks, were used to mark membranes immediately before the addition of cells. In the second experiment, the same marker pens marked the membranes after 7 days of cell culture. In each experiment, 3 groups of membrane were tested for each pen. Group A consisted of no ink mark, group B had only the uppermost “smooth” layer marked, and group C had the lower “porous” layer marked. All membranes were then cultured in standard growth media for 24 hours. Cell viability was assessed at 24 hours on all membranes using a live/dead-cell viability assay. Cell viability was quantified with florescent microscopy with mean percentage of live cells in each marker pen group compared with control membranes using the Student t test ( P < .05).

Results: Control membranes (group A) with no ink showed cell viability approaching 100%. A statistically significant reduction in cell viability with both methylene blue (23.1%; P < .0001) and crystal violet (18.9%; P < .0001) was found adjacent to the ink mark on the smooth side (group B) and on the porous side remote from the ink (group C) in both experiments (<30%; P < .0001). Areduction in cell viability was noted on the smooth side remote from the ink mark but did not reach statistical significance. Marked cell death was seen with both dyes (<15%; P < .0001) adjacent to the ink on the porous side.

Conclusion: Chondrocyte viability is significantly reduced when cells are cultured in vitro on collagen membranes marked with methylene blue and crystal violet pen ink.

Clinical Relevance: Surgeons should be aware of the potential negative effect of marker pens in cell-based therapies.
Relationship Between the Medial Elbow Adduction Moment During Pitching and Ulnar Collateral Ligament Appearance During Magnetic Resonance Imaging Evaluation
Authors: Hurd Wendy J. , Kaufman Kenton R. , Murthy Naveen S.
Published: February 2011

Background: Medial elbow distraction during pitching as the primary mechanism contributing to adaptations in ulnar collateral ligament (UCL) appearance during magnetic resonance imaging (MRI) evaluation has not been established.

Hypothesis: Uninjured high school–aged pitchers with unilateral adaptations of the UCL exhibit a higher peak internal elbow adduction moment than those without UCL adaptations.

Study Design: Cohort study (Prevalence); Level of evidence, 2.

Methods: Twenty uninjured, asymptomatic high school–aged pitchers underwent bilateral elbow MRI examinations. Three-dimensional motion analysis testing was performed to collect throwing arm biomechanics as participants pitched from an indoor mound. Nonparametric tests were performed to compare peak internal elbow adduction moment in uninjured participants with and without adaptations in UCL appearance and to determine the nature of the relationship between the peak internal adduction moment and UCL appearance.

Results: Uninjured participants with UCL thickening exhibited a higher peak internal elbow adduction moment of 53.3 ± 6.8 N·m compared with uninjured participants without adaptations in UCL appearance, 38.8 ± 10.9 N·m ( P = .05), as higher moments were correlated with ligament thickening (correlation coefficient, 0.45) ( P = .02).

Conclusion: This study establishes the association between medial elbow distraction captured by the internal adduction moment during pitching and UCL adaptations visible during MRI evaluation.