bluuebunny/crossref_metadata_2025 huggingface dataset:
Implantable Defibrillators With Enhanced Detection Algorithms: Detection Performance and Safety Results from the PainFree SST Study
Authors: WOLLMANN CHRISTIAN G. , LAWO THOMAS , KÜHLKAMP VOLKER , BECKER RÜDIGER , GARUTTI CLAUDIO , JACKSON TROY , BROWN MARK L. , MAYR HARALD
Published: March 2014

Background

Implantable defibrillators (ICD) are highly effective in reducing arrhythmia‐related mortality. ICD shock therapy has been shown to increase psychological distress, health care utilization, and is associated with increased mortality. The Protecta ICDs (Medtronic Inc., Minneapolis, MN, USA) have algorithms designed to reduce unnecessary and inappropriate shock therapy.

Methods and Results

The PainFree SmartShock™ Technology (PainFree SST) study is a prospective, multicenter, clinical trial with two consecutive phases, a premarket phase safety study and a postmarket phase effectiveness study. We report the results of the PainFree SST safety study.

The premarket phase aimed to investigate safety in the first year postimplant, and to determine if the novel algorithms (T‐wave discrimination, right ventricular lead noise discrimination and confirmation+) affect appropriate ventricular fibrillation (VF) detection. Patients (total: n = 246 [male 78%, mean age 63 year, primary prevention indication in 76%]) were implanted either with a Protecta XT dual‐chamber ICD (n = 114 [46%]) or a defibrillator with cardiac resynchronization therapy (n = 132 [54%]). Appropriate VF detection was measured during VF induction at implantation when the novel algorithms were programmed ON. A two‐second delay in VF detection was classified as clinically significant. No delay in VF detection was observed with all algorithms programmed ON. No unanticipated serious adverse device effects occurred during first year postimplant.

Conclusion

The results of the premarket phase of the PainFree SST trial demonstrate the safety of the Protecta XT defibrillators. Detection of induced VF was not delayed with SmartShock™ algorithms ON.
Effects of Ventilation and Catheter Position on Catheter Movement on the Tricuspid Annulus during Ablation in Children
Authors: CERESNAK SCOTT R. , KAHANA MADELYN , ZUCKER HOWARD A. , MANN GLENN , NAPPO LYNN , PASS ROBERT H.
Published: March 2014

Introduction

There are little data on the effect of catheter position and mechanical ventilation on ablation catheter stability during electrophysiology study in children. We sought to determine the magnitude of catheter movement with mechanical ventilation, the effect of ventilation maneuvers on catheter movement, and to compare the degree of movement observed between the right lateral (RL) and right posteroseptal (RPS) regions.

Methods

From June 2012 to June 2013, patients ≤21 years of age undergoing ablation for supraventricular tachycardia with CARTO® 3 (Biosense Webster, Diamond Bar, CA, USA) were included. During mapping the ablation catheter was placed in the RPS and RL regions and the magnitude of catheter movement (mm) was measured using CARTO® 3. Measurements were made during routine ventilation and with a maximal inspiration maneuver between end‐expiration (ENDEX) and peak‐inspiration (PEAKINS).

Results

Twenty‐one patients were included: 12 males (57%), age 13 ± 3 years, weight 55 ± 14 kg. Indications for ablation were: 10 Wolff‐Parkinson‐White, seven atrioventricular node re‐entry tachycardia, four concealed accessory pathway. Mechanical ventilation was used in all cases. The magnitude of catheter movement was 3.6 ± 1.7 mm with routine ventilation and 6.2 ± 4.1 mm between ENDEX and PEAKINS (P ≤ 0.01). Catheter movement was greater in the RL compared to the RPS region with routine ventilation (RL 4.3 ± 1.6 vs RPS 3.0 ± 1.5; P < 0.01) and between ENDEX and PEAKINS (RL 8.3 ± 4.7 vs RPS 4.0 ± 1.7; P < 0.01).

Conclusions

Ventilation and catheter position both have significant impact on the degree of catheter movement during ablation. Movement was greatest in the RL position. This may partially explain the lower success rates of ablation in the RL region.
Ketofol simulations for dosing in pediatric anesthesia
Authors: Coulter Finn L. S. , Hannam Jacqueline A. , Anderson Brian J.
Published: March 2014

Background

Propofol mixed with racemic ketamine (or ‘ketofol’) is popular for short procedural sedation and analgesia. Use is creeping into anesthesia, yet neither the optimal combination nor infusion rate is known. The EC50 of propofol's antiemetic effect is reported to be 0.343 mg·l−1, while ketamine analgesia is thought to persist with concentrations above 0.2 mg·l−1. We aimed to determine a ketofol dosing regimen for anesthesia 30‐min and 1.5‐h duration in a healthy child that did not unduly compromise recovery.

Methods

Pharmacokinetic–pharmacodynamic parameters were used to simulate drug concentration and effect profiles over time for different ratios of propofol to ketamine ratios (1 : 1 to 10 : 1) and rates. The target effect was the 95% probability of loss of response to a 5‐s transcutaneous tetanus (P05). Combined effects were additive, with a propofol EC50 of 3.1 mg·l−1, ketamine EC50 of 0.64 mg·l−1, and slope of 5.4. The time to predicted 50% probability of return of this response after ceasing infusion (P50) was determined for a 5‐year‐old 20‐kg healthy child.

Results

The addition of ketamine to propofol infused using a manual infusion regimen (loading dose 3 mg·kg−1, then 15 mg·kg−1·h−1 for 15 min, 13 mg·kg−1·h−1 for 15 min, 11 mg·kg−1·h−1 for 30 min, and 10 mg·kg−1·h−1 for 1–2 h) caused prolonged postoperative sedation. The P50 after a 1.5‐h infusion using a 1 : 1 mixture was 4.5 h, 2 : 1 mixture was 3.25 h, 5 : 1 mixture was 1.6 h, and 10 : 1 mixture was 40 min. These P50 estimates could be reduced by slowing administration infusion rates to 20%, 33%, 50%, 67%, 80%, and 90% for mixtures 1 : 1, 2 : 1, 3 : 1, 5 : 1, 6.7 : 1, and 10 : 1, respectively. These rates achieve a P50 of approximately 20 min for 30‐min duration anesthesia and 60 min for 1.5‐h duration anesthesia.

Conclusions

The addition of ketamine to propofol infusion will prolong recovery unless infusion rates are decreased. We suggest an optimal ratio of racemic ketamine to propofol of 1 : 5 for 30‐min anesthesia and 1 : 6.7 for 90‐min anesthesia. Delivery of these ratios achieves propofol concentrations above an antiemetic threshold for longer than the ketamine concentration above the analgesic threshold during, potentially reducing postoperative nausea incidence.
A review of the surface and internal anatomy of the caudal canal in children
Authors: Lees David , Frawley Geoff , Taghavi Kiarash , Mirjalili Seyed Ali
Published: March 2014

The anatomy of the sacral hiatus and caudal canal is prone to significant variation, yet studies assessing this in the pediatric population remain limited. Awareness of the possible anatomical variations is critical to the safety and success of caudal epidural blocks, particularly when image guidance is not employed. This systematic review analyzes the available evidence on the clinical anatomy of the caudal canal in pediatric patients, emphasizing surface anatomy and internal anatomical variations. A literature search using three electronic databases and standard pediatric and anatomy reference texts was conducted yielding 24 primary and seven secondary English‐language sources. Appreciating that our current landmark‐guided approaches to the caudal canal are not well studied in the pediatric population is important for both clinicians and researchers.
Cost Utility Analysis of Percutaneous Adhesiolysis in Managing Pain of Post‐lumbar Surgery Syndrome and Lumbar Central Spinal Stenosis
Authors: Manchikanti Laxmaiah , Helm Standiford , Pampati Vidyasagar , Racz Gabor B.
Published: March 2014

Background

The increase in the number of interventions for the management of chronic pain and associated escalation of healthcare costs has captured the attention of health policymakers, in no small part due to the lack of documentation of efficacy, cost‐effectiveness, or cost utility analysis. A recent cost utility analysis of caudal epidural injections in managing chronic low back pain of various pathologies showed a high cost utility with improvement in quality of life years, competitive with various other modalities of treatments. However, there are no analyses derived from high‐quality controlled studies related to the cost utility of percutaneous adhesiolysis in the treatment of post‐lumbar surgery syndrome or lumbar central spinal stenosis.

Study Design

This analysis is based on 2 previously published controlled studies.

Objective

To assess the cost utility of percutaneous adhesiolysis procedures in managing chronic low back and lower extremity pain secondary to post‐lumbar surgery syndrome and lumbar central spinal stenosis.

Setting

A private, specialty referral interventional pain management center in the United States.

Methods

Two controlled studies were conducted assessing the clinical effectiveness of percutaneous adhesiolysis for post‐lumbar surgery syndrome and lumbar central spinal stenosis in an interventional pain management setting utilizing contemporary interventional pain management practices. A cost utility analysis was performed with direct payment data for a total of 130 patients in treatment groups over a 2‐year period. Various outcome measures were included with significant improvement, defined as at least 50% improvement with reduction in pain and disability status.

Results

The results of 2 controlled studies of low back pain with 60 and 70 patients and a 2‐year follow‐up with the actual reimbursement data showed cost utility for 1 year of quality‐adjusted life year (QALY) of USD $2,652 for post‐lumbar surgery syndrome and USD $2,649 for lumbar central spinal stenosis. The results of this assessment show that the cost utility of managing chronic, intractable low back pain with percutaneous adhesiolysis at a QALY that is similar or lower in price than medical therapy only, physical therapy, manipulation, spinal cord stimulation, and surgery.

Limitations

The limitations of this cost utility analysis are that it is a single‐center evaluation, with the inclusion of costs of adhesiolysis procedures in an ambulatory surgery center and physician visits, rather than all related costs including drug therapy and costs of disability in multiple settings.

Conclusion

This cost utility analysis of percutaneous adhesiolysis in the treatment of post‐lumbar surgery syndrome and lumbar central spinal stenosis shows the clinical effectiveness and cost utility of these procedures at USD $2,650 per one year of QALY when performed in an ambulatory surgery center.
A peptide hormone gene, GhPSK promotes fibre elongation and contributes to longer and finer cotton fibre
Authors: Han Jie , Tan Jiafu , Tu Lili , Zhang Xianlong
Published: March 2014

Cotton fibres, the single‐celled trichomes derived from the ovule epidermis, provide the most important natural material for the global textile industry. A number of studies have demonstrated that regulating endogenous hormone levels through transgenic approaches can improve cotton fibre qualities. Phytosulfokine‐α (PSK‐α) is a novel peptide hormone in plants that is involved in regulating cell proliferation and elongation. However, its potential applications in crop genetic improvement have not been evaluated. In this study, we describe how exogenous PSK‐α application promotes cotton fibre cell elongation in vitro. Chlorate, an effective inhibitor of peptide sulfation, suppressed fibre elongation in ovule culture. Exogenously applied PSK‐α partly restored the chlorate‐induced suppression. A putative PSK gene (GhPSK) was cloned from Gossypium hirsutum. Expression pattern analysis revealed that GhPSK is preferentially expressed in rapidly elongating fibre cells (5–20 days postanthesis). Overexpression of GhPSK in cotton increased the endogenous PSK‐α level and promoted cotton fibre cell elongation, resulting in longer and finer fibres. Further results from electrophysiological and physiological analyses suggest that GhPSK affects fibre development through regulation of K+ efflux. Digital gene expression (DGE) profile analysis of GhPSK overexpression lines indicates that PSK signalling may regulate the respiratory electron‐transport chain and reactive oxygen species to affect cotton fibre development. These results imply that peptide hormones are involved in cotton fibre growth and suggest a new strategy for the biotechnological improvement of cotton fibre quality.
Darwin‐Wallace Demons: survival of the fastest in populations of duckweeds and the evolutionary history of an enigmatic group of angiosperms
Authors: Kutschera U. , Niklas K. J.
Published: March 2014

In evolutionary biology, the term ‘Darwinian fitness’ refers to the lifetime reproductive success of an individual within a population of conspecifics. The idea of a ‘Darwinian Demon’ emerged from this concept and is defined here as an organism that commences reproduction almost immediately after birth, has a maximum fitness, and lives forever. It has been argued that duckweeds (sub‐family Lemnoideae, order Alismatales), a group containing five genera and 34 species of small aquatic monocotyledonous plants with a reduced body plan, can be interpreted as examples of ‘Darwinian Demons’. Here we focus on the speciesSpirodela polyrhiza(Great duckweed) and show that these miniaturised aquatic angiosperms display features that fit the definition of the hypothetical organism that we will call a ‘Darwin‐Wallace Demon’ in recognition of the duel proponents of evolution by natural selection. A quantitative analysis (log‐log bivariate plot of annual growth in dry biomassversusstanding dry body mass of various green algae and land plants) revealed that duckweeds are thus far the most rapidly growing angiosperms in proportion to their body mass. In light of this finding, we discuss the disposable soma and metabolic optimising theories, summarise evidence for and against the proposition that the Lemnoideae (family Araceae) reflect an example of reductive evolution, and argue that, under real‐world conditions (environmental constraints and other limitations), ‘Darwin‐Wallace Demons’ cannot exist, although the concept remains useful in much the same way that the Hardy–Weinberg law does.
Association of HLA‐B27 and ERAP1 with ankylosing spondylitis susceptibility in Beijing Han Chinese
Authors: Zhang Z. , Dai D. , Yu K. , Yuan F. , Jin J. , Ding L. , Hao Y. , Liang F. , Liu N. , Zhao X. , Long J. , Xi Y. , Sun Y.‐Y.
Published: March 2014

This study investigated the genetic polymorphisms of HLA‐B27, together with polymorphisms on endoplasmic reticulum aminopeptidase 1 (ERAP1), and susceptibility for ankylosing spondylitis (AS) in the Beijing Han population. A case‐control study was carried out for 602 AS patient samples and 619 matched controls of Han Chinese. HLA‐B27 genotyping was performed by polymerase chain reaction‐sequence specific primers (PCR‐SSP), and four ERAP1 SNPs (rs27037, rs27980, rs27582, and rs27434) were selected and genotyped on the Sequenom iPlex platform (Sequenom, San Diego, CA). Association analysis was performed using the likelihood ratio χ2 test. This study identified four HLA‐B27 alleles in Beijing Han AS patients, B*27:02, B*27:04, B*27:05, and B*27:07, of which B*27:05 was the most significant geographical different subtype among AS patients in Chinese. Our results confirmed that HLA‐B27 was strongly associated with AS (P = 1.9 × 10−150), and the most strongly associated alleles were B*27:04, B*27:05, and B*27:02. Our study also confirmed a weak association between ERAP1 (rs27434) and AS. We also observed that for HLA‐B*27:02 and HLA‐B*27:04 positive AS patients, rs27434 and rs27582 were associated with AS. In contrast, for HLA‐B27‐negative and HLA‐B*27:05‐positive AS patients, this association was not observed. This is the first study to show that both B27 and ERAP1 are AS genetic susceptibility genes in Beijing Han. Interactions between ERAP1 and HLA‐B*27:02 and B*27:04 may play an important role in the AS pathogenesis.
Fipronil–amitraz–S‐methoprene‐triggered pemphigus foliaceus in 21 dogs: clinical, histological and immunological characteristics
Authors: Bizikova Petra , Linder Keith E. , Olivry Thierry
Published: March 2014

Background

A recently launched topical ectoparasiticide containing fipronil, amitraz and S‐methoprene has been associated with the development of an acantholytic pustular dermatitis similar to that of Promeris‐triggered pemphigus foliaceus (PF).

Hypothesis/Objectives

Our objectives were to describe the clinical, histological and immunological features of this PF‐like cutaneous adverse drug reaction.

Animals

Twenty‐one dogs with a probable or definitive diagnosis of PF‐like cutaneous adverse drug reaction were identified between May 2012 and February 2013.

Material and Methods

Histology, direct and indirect immunofluorescence were employed to address the study objectives.

Results

Most dogs were middle‐aged or older (median, 9 years) and of large size (median, 23 kg). In six dogs (29%), the PF‐like lesions remained confined to the site of application, while 15 dogs (71%) exhibited lesions at distant sites. One or two applications of the ectoparasiticide were sufficient to trigger PF‐like lesions in seven (33%) and six (29%) dogs, respectively. Systemic signs were reported in nine dogs (43%), all with lesions extending to sites distant from application areas. Tissue‐bound antikeratinocyte IgG was detected in the lesional epidermis of eight of 19 (42%) cases by direct immunofluorescence, while serum antikeratinocyte IgG was detected in 10 of 14 (71%) cases by indirect immunofluorescence. Autoantibodies were found to target canine desmocollin‐1 in 11 of 14 dogs (79%), but not canine desmoglein‐1, by indirect immunofluorescence on transfected cells. These immunological findings were similar in cases with localized and distant disease.

Conclusions and clinical importance

This new topical ectoparasiticide containing fipronil, amitraz and S‐methoprene is capable of triggering the development of an acantholytic pustular dermatosis that is a clinical, histological and immunological close match for Promeris‐triggered PF and naturally occurring autoimmune PF in dogs.
Galois representations attached to automorphic forms on over fields
Authors: Mok Chung Pang
Published: March 2014

In this paper we generalize the work of Harris–Soudry–Taylor and construct the compatible systems of two-dimensional Galois representations attached to cuspidal automorphic representations of cohomological type on${\rm GL}_2$over a CM field with a suitable condition on their central characters. We also prove a local-global compatibility statement, up to semi-simplification.
On a completed generating function of locally harmonic Maass forms
Authors: Bringmann Kathrin , Kane Ben , Zwegers Sander
Published: March 2014

While investigating the Doi–Naganuma lift, Zagier defined integral weight cusp forms$f_D$which are naturally defined in terms of binary quadratic forms of discriminant$D$. It was later determined by Kohnen and Zagier that the generating function for the function$f_D$is a half-integral weight cusp form. A natural preimage of$f_D$under a differential operator at the heart of the theory of harmonic weak Maass forms was determined by the first two authors and Kohnen. In this paper, we consider the modularity properties of the generating function of these preimages. We prove that although the generating function is not itself modular, it can be naturally completed to obtain a half-integral weight modular object.
Wave Propagation and Power Flow Analysis of Sandwich Structures With Internal Absorbers
Authors: Chen J. S. , Wang R. T.
Published: March 2014

This study examines wave attenuation and power flow characteristics of sandwich beams with internal absorbers. Two types of absorbing systems embedded in the core are considered, namely, a conventional spring-mass-dashpot system having a mass with a spring and a dashpot in parallel, and a relaxation system containing an additional relaxation spring added in series with the dashpot. Analytical continuum models used for interpreting the attenuation behavior of sandwich structures are presented. Through the analysis of the power flowing into the structure, the correlation of wave attenuation and energy blockage is revealed. The reduction in the power flow indicates that some amount of energy produced by the external force can be effectively obstructed by internal absorbers. The effects of parameters on peak attenuation, bandwidth, and power flow are also studied.
System Level Analysis of Acoustically Forced Nonpremixed Swirling Flames
Authors: Idahosa Uyi , Basu Saptarshi , Miglani Ankur
Published: March 2014

This paper reports an experimental investigation of dynamic response of nonpremixed atmospheric swirling flames subjected to external, longitudinal acoustic excitation. Acoustic perturbations of varying frequencies (fp = 0–315 Hz) and velocity amplitudes (0.03 ≤ u′/Uavg ≤ 0.30) are imposed on the flames with various swirl intensities (S = 0.09 and 0.34). Flame dynamics at these swirl levels are studied for both constant and time-dependent fuel flow rate configurations. Heat release rates are quantified using a photomultiplier (PMT) and simultaneously imaged with a phase-locked CCD camera. The PMT and CCD camera are fitted with 430 nm ±10 nm band pass filters for CH* chemiluminescence intensity measurements. Flame transfer functions and continuous wavelet transforms (CWT) of heat release rate oscillations are used in order to understand the flame response at various burner swirl intensity and fuel flow rate settings. In addition, the natural modes of mixing and reaction processes are examined using the magnitude squared coherence analysis between major flame dynamics parameters. A low-pass filter characteristic is obtained with highly responsive flames below forcing frequencies of 200 Hz while the most significant flame response is observed at 105 Hz forcing mode. High strain rates induced in the flame sheet are observed to cause periodic extinction at localized regions of the flame sheet. Low swirl flames at lean fuel flow rates exhibit significant localized extinction and re-ignition of the flame sheet in the absence of acoustic forcing. However, pulsed flames exhibit increased resistance to straining due to the constrained inner recirculation zones (IRZ) resulting from acoustic perturbations that are transmitted by the co-flowing air. Wavelet spectra also show prominence of low frequency heat release rate oscillations for leaner (C2) flame configurations. For the time-dependent fuel flow rate flames, higher un-mixedness levels at lower swirl intensity is observed to induce periodic re-ignition as the flame approaches extinction. Increased swirl is observed to extend the time-to-extinction for both pulsed and unpulsed flame configurations under time-dependent fuel flow rate conditions.
Natural zwitterionic organosulfurs as surface ligands for antifouling and responsive properties
Authors: Huang Chun-Jen , Wang Lin-Chuan , Liu Chia-Yu , Chiang Anthony S. T. , Chang Ying-Chih
Published: March 2014

Natural sulfur-containing zwitterionic compounds, l-cysteine (Cys), l-methionine, and glutathionine (GSH), have been employed as surface ligands to prevent protein nonspecific adsorption on planar substrates. These organosulfur compounds form self-assembled monolayers (SAMs) on gold substrates by gold–sulfur interaction. The chemical elements of SAMs were confirmed using x-ray photoelectron spectroscopy. The surface wetting tests for SAMs show that films prepared from Cys and GSH exhibited super-hydrophilicity (contact angles of θ = ∼5°) due to their high coverage and strong hydration via ionic solvation and formation of hydrogen bonding. Quartz crystal microbalance with dissipation sensor was used to quantitatively and qualitatively monitor the adsorption of bovine serum albumin (BSA) from buffer onto these SAMs. It was found that the GSH film enables the resistance of BSA adsorption to the best extent at a physiological pH. Moreover, the surface charges of modified substrates were modulated by varying the pH value to control BSA adsorption. The effect of electrostatic repulsion on the antifouling behavior becomes prominent at a pH where the protein and the surface carry same charges. Consolidating the BSA adsorption measurements at different pH values, the antifouling properties of GSH-modified Au should be attributed to prevention of entropy gain and enthalpy loss, making BSA adsorption energetically unfavorable. It is believed that the surface modification with natural organosulfur ligands holds great potential in improving the biocompatibility of medical devices and in offering intelligent biointerfaces in response to environmental stimuli.
Automated bone segmentation from dental CBCT images using patch‐based sparse representation and convex optimization
Authors: Wang Li , Chen Ken Chung , Gao Yaozong , Shi Feng , Liao Shu , Li Gang , Shen Steve G. F. , Yan Jin , Lee Philip K. M. , Chow Ben , Liu Nancy X. , Xia James J. , Shen Dinggang
Published: March 2014

Purpose:

Cone‐beam computed tomography (CBCT) is an increasingly utilized imaging modality for the diagnosis and treatment planning of the patients with craniomaxillofacial (CMF) deformities. Accurate segmentation of CBCT image is an essential step to generate three‐dimensional (3D) models for the diagnosis and treatment planning of the patients with CMF deformities. However, due to the poor image quality, including very low signal‐to‐noise ratio and the widespread image artifacts such as noise, beam hardening, and inhomogeneity, it is challenging to segment the CBCT images. In this paper, the authors present a new automatic segmentation method to address these problems.

Methods:

To segment CBCT images, the authors propose a new method for fully automated CBCT segmentation by using patch‐based sparse representation to (1) segment bony structures from the soft tissues and (2) further separate the mandible from the maxilla. Specifically, a region‐specific registration strategy is first proposed to warp all the atlases to the current testing subject and then a sparse‐based label propagation strategy is employed to estimate a patient‐specific atlas from all aligned atlases. Finally, the patient‐specific atlas is integrated into amaximum a posterioriprobability‐based convex segmentation framework for accurate segmentation.

Results:

The proposed method has been evaluated on a dataset with 15 CBCT images. The effectiveness of the proposed region‐specific registration strategy and patient‐specific atlas has been validated by comparing with the traditional registration strategy and population‐based atlas. The experimental results show that the proposed method achieves the best segmentation accuracy by comparison with other state‐of‐the‐art segmentation methods.

Conclusions:

The authors have proposed a new CBCT segmentation method by using patch‐based sparse representation and convex optimization, which can achieve considerably accurate segmentation results in CBCT segmentation based on 15 patients.
The Schwarzschild metric: It's the coordinates, stupid!
Authors: Fromholz Pierre , Poisson Eric , Will Clifford M.
Published: March 2014

Every general relativity textbook emphasizes that coordinates have no physical meaning. Nevertheless, a coordinate choice must be made in order to carry out real calculations, and that choice can make the difference between a calculation that is simple and one that is a mess. We give a concrete illustration of the maxim that “coordinates matter” using the exact Schwarzschild solution for a vacuum, static spherical spacetime. We review the standard textbook derivation, Schwarzschild's original 1916 derivation, and a derivation using the Landau-Lifshitz formulation of the Einstein field equations. The last derivation is much more complicated, has one aspect for which we have been unable to find a solution, and gives an explicit illustration of the fact that the Schwarzschild geometry can be described in infinitely many coordinate systems.
Quick and easy escape from a metastable state
Authors: Garg Anupam
Published: March 2014

An elementary but complete calculation of metastable state decay from a piecewise-constant one-dimensional potential well is presented that does not invoke the concept of an attempt frequency or require a knowledge of the Wentzel-Kramers-Brillouin method. Connection is made with scattering resonances for advanced readers.
Understanding current signals induced by drifting electrons
Authors: Recine Kristen A. , Battat James B. R. , Henderson Shawn
Published: March 2014

Consider an electron drifting in a gas toward a collection electrode. A common misconception is that the electron produces a detectable signal only upon arrival at the electrode. In fact, the situation is quite the opposite. The electron induces a detectable current in the electrode as soon as it starts moving through the gas. This induced current vanishes when the electron arrives at the plate. To illustrate this phenomenon experimentally, we use a gas-filled parallel-plate ionization chamber and a collimated 241Am alpha source, which produces a track of a fixed number of ionization electrons at a constant distance from the collection electrode. We find that the detected signal from the ionization chamber grows with the electron drift distance, as predicted by the model of charge induction, and in conflict with the idea that electrons are detectable upon arrival at the collection plate.
Shoulder Kinematics Is Not Influenced by External Load During Elevation in the Scapular Plane
Authors: de Castro Marcelo P. , Ribeiro Daniel Cury , Forte Felipe de C. , de Toledo Joelly M. , Aldabe Daniela , Loss Jefferson F.
Published: March 2014

The current study aimed to compare the shoulder kinematics (3D scapular orientation, scapular angular displacement and scapulohumeral rhythm) of asymptomatic participants under unloaded and loaded conditions during unilateral shoulder elevation in the scapular plane. We used a repeated-measures design with a convenience sample. Eleven male participants with an age range of 21–28 years with no recent history of shoulder injury participated in the study. The participants performed isometric shoulder elevation from a neutral position to approximately 150 degrees of elevation in the scapular plane in intervals of approximately 30 degrees during unloaded and loaded conditions. Shoulder kinematic data were obtained with videogrammetry. During shoulder elevation, the scapula rotated upwardly and externally, and tilted posteriorly. The addition of an external load did not affect 3D scapular orientation, scapular angular displacement, or scapulohumeral rhythm throughout shoulder elevation (P > .05). In clinical practice, clinicians should expect to observe upward and external rotation and posterior tilt of the scapula during their assessments of shoulder elevation. Such behavior was not influenced by an external load normalized to 5% of body weight when performed in an asymptomatic population.
Comparison of Stance Phase Knee Joint Angles and Moments Using Two Different Surface Marker Representations of the Proximal Shank in Walkers and Runners
Authors: Petit Daniel J. , Willson John D. , Barrios Joaquin A.
Published: March 2014

Efforts to compare different surface marker configurations in 3-dimensional motion analysis are warranted as more complex and custom marker sets become more common. At the knee, different markers can been used to represent the proximal shank. Often, two anatomical markers are placed over the femoral condyles, with their midpoint defining both the distal thigh and proximal shank segment ends. However, two additional markers placed over the tibial plateaus have been used to define the proximal shank end. For this experiment, simultaneous data for both proximal shank configurations were independently collected at two separate laboratories by different investigators, with one laboratory capturing a walking population and the other a running population. Common discrete knee joint variables were then compared between marker sets in each population. Using the augmented marker set, peak knee flexion after weight acceptance was less (1.2−1.7°, P < .02) and peak knee adduction was greater (0.7−1.4°, P < .001) in both data sets. Similarly, the calculated peak knee flexion moment was less by 15–20% and internal rotation moment was greater by 11–18% (P < .001). These results suggest that the calculation of knee joint mechanics are influenced by the proximal shank’s segment endpoint definition, independent of dynamic task, investigator, laboratory environment, and population in this study.
Human Carrying Simulation With Symmetric and Asymmetric Loads Using Optimization
Authors: Xiang Yujiang
Published: March 2014

Human carrying is simulated in this work by using a skeletal digital human model with 55 degrees of freedom. An optimization-based approach is used to predict the carrying motion with symmetric and asymmetric loads. In this process, the model predicts joint dynamics using optimization schemes and task-based physical constraints. The results indicate that the model can predict different carrying strategies during symmetric and asymmetric load-carrying tasks. The model can also indicate the risk factors for extreme loading situations. With such robust prediction capability, the model could be used for biomedical and ergonomic studies.
Evaluating the Acromion Marker Cluster as a Method for Measuring Scapular Orientation in Children With Brachial Plexus Birth Palsy
Authors: Nicholson Kristen F. , Russo Stephanie A. , Kozin Scott H. , Zlotolow Dan A. , Hulbert Robert L. , Rowley K. Michael , Richards James G.
Published: March 2014

Several studies have described using an acromion marker cluster for measuring scapular orientation in healthy adults performing planar motions. It is unknown whether the acromion marker cluster method will provide the same level of accuracy in children with brachial plexus birth palsy. This study compared this method to palpation for calculating scapular orientation in children with brachial plexus birth palsy performing clinically relevant movements. Scapular orientation in ten patients was determined by palpation and an acromion marker cluster in neutral and six Modified Mallet positions. RMSEs and mean relative errors were calculated. Resultant RMSEs ranged from 5.2 degrees to 21.4 degrees. The averages of the mean relative errors across all positions for each axis were 177.4% for upward/downward rotation, 865.0% for internal/external rotation, and 166.2% for anterior/posterior tilt. The acromion marker cluster method did not accurately measure scapular rotation relative to the total movement on an individual or group basis in the population. With most relative errors over 100%, the acromion marker cluster method often produced errors larger than the actual measured motion. The accuracy of the acromion marker cluster method limits its use as a clinical tool for measuring scapular kinematics on children with brachial plexus birth palsy.
Relationship Between Tibial Acceleration and Proximal Anterior Tibia Shear Force Across Increasing Jump Distance
Authors: Sell Timothy C. , Akins Jonathan S. , Opp Alexis R. , Lephart Scott M.
Published: March 2014

Proximal anterior tibia shear force is a direct loading mechanism of the anterior cruciate ligament (ACL) and is a contributor to ACL strain during injury. Measurement of this force during competition may provide insight into risk factors for ACL injury. Accelerometers may be capable of measuring tibial acceleration during competition. The purpose of this study was to examine the relationship between acceleration measured by a tibia-mounted accelerometer and proximal anterior tibia shear force as measured through inverse dynamics and peak posterior ground reaction forces during two leg stop-jump tasks. Nineteen healthy male subjects performed stop-jump tasks across increasing jump distances. Correlation coefficients were calculated to determine if a relationship exists between accelerometer data and proximal anterior tibia shear force and peak posterior ground reaction force. An analysis of variance was performed to compare these variables across jump distance. Significant correlations were observed between accelerometer data and peak posterior ground reaction force, but none between accelerometer data and proximal anterior tibia shear force. All variables except peak proximal anterior tibia shear force increased significantly as jump distance increased. Overall, results of this study provide initial, positive support for the use of accelerometers as a useful tool for future injury prevention research.
The Relationship Between Spatiotemporal Gait Asymmetry and Balance in Individuals With Chronic Stroke
Authors: Lewek Michael D. , Bradley Claire E. , Wutzke Clinton J. , Zinder Steven M.
Published: March 2014

Falls are common after stroke and often attributed to poor balance. Falls often occur during walking, suggesting that walking patterns may induce a loss of balance. Gait after stroke is frequently spatiotemporally asymmetric, which may decrease balance. The purpose of this study is to determine the relationship between spatiotemporal gait asymmetry and balance control. Thirty-nine individuals with chronic stroke walked at comfortable and fast speeds to calculate asymmetry ratios for step length, stance time, and swing time. Balance measures included the Berg Balance Scale, step width during gait, and the weight distribution between legs during standing. Correlational analyses determined the relationships between balance and gait asymmetry. At comfortable and fast gait speeds, step width was correlated with stance time and swing time asymmetries (r = 0.39−0.54). Berg scores were correlated with step length and swing time asymmetries (r = –0.36 to –0.63). During fast walking, the weight distribution between limbs was correlated with stance time asymmetry (r = –0.41). Spatiotemporal gait asymmetry was more closely related to balance measures involving dynamic tasks than static tasks, suggesting that gait asymmetry may be related to the high number of falls poststroke. Further study to determine if rehabilitation that improves gait asymmetry has a similar influence on balance is warranted.
A Kinetic and Kinematic Analysis of the Effect of Stochastic Resonance Electrical Stimulation and Knee Sleeve During Gait in Osteoarthritis of the Knee
Authors: Collins Amber , Blackburn Troy , Olcott Chris , Jordan Joanne M. , Yu Bing , Weinhold Paul
Published: March 2014

Extended use of knee sleeves in populations at risk for knee osteoarthritis progression has shown functional and quality of life benefits; however, additional comprehensive kinematic and kinetic analyses are needed to determine possible physical mechanisms of these benefits which may be due to the sleeve’s ability to enhance knee proprioception. A novel means of extending these enhancements may be through stochastic resonance stimulation. Our goal was to determine whether the use of a knee sleeve alone or combined with stochastic resonance electrical stimulation improves knee mechanics in knee osteoarthritis. Gait kinetics and kinematics were assessed in subjects with medial knee osteoarthritis when presented with four conditions: control1, no electrical stimulation/sleeve, 75% threshold stimulation/sleeve, and control2. An increase in knee flexion angle throughout stance and a decrease in flexion moment occurring immediately after initial contact were seen in the stimulation/sleeve and sleeve alone conditions; however, these treatment conditions did not affect the knee adduction angle and internal knee abduction moment during weight acceptance. No differences were found between the sleeve alone and the stochastic resonance with sleeve conditions. A knee sleeve can improve sagittal-plane knee kinematics and kinetics, although adding the current configuration of stochastic resonance did not enhance these effects.
Age- and Activity-Related Differences in the Mechanisms Underlying Maximal Power Production in Young and Older Adults
Authors: Korff Thomas , Newstead Ann H. , van Zandwijk Renate , Jensen Jody L.
Published: March 2014

The purpose of this study was to examine the interactions between aging, activity levels and maximal power production during cycling. Participants were divided into younger adults (YA), older active adults (OA,) and older sedentary adults (OS). Absolute maximum power was significantly greater in YA compared with OS and OA; no differences were found between OA and OS. The age-related difference in maximum power was accompanied by greater absolute peak knee extension and knee flexion powers. Relative joint power contributions revealed both age- and activity-related differences. YA produced less relative hip extension power than older adults, regardless of activity level. The OS participants produced less relative knee flexion power than active adults, regardless of age. The results show the age-related decline in muscular power production is joint specific and that activity level can be a modifier of intersegmental coordination, which has implications for designing interventions for the aging population.
Changes in the Preferred Transition Speed With Added Mass to the Foot
Authors: MacLeod Toran D. , Hreljac Alan , Imamura Rodney
Published: March 2014

This study was conducted to investigate whether adding mass to subjects’ feet affects the preferred transition speed (PTS), and to ascertain whether selected swing phase variables (maximum ankle dorsiflexion angular velocity, angular acceleration, joint moment, and joint power) are determinants of the PTS, based upon four previously established criteria. After the PTS of 24 healthy active male subjects was found, using an incremental protocol in loaded (2 kg mass added to each shoe) and unloaded (shoes only) conditions, subjects walked at three speeds (60%, 80%, and 100% of PTS) and ran at one speed (100% of PTS) on a motor-driven treadmill while relevant data were collected. The PTS of the unloaded condition (2.03 ± 0.12 m/s) was significantly greater (P < .05) than the PTS of the loaded condition (1.94 ± 0.13 m/s). Within both load conditions, all dependent variables increased significantly with walking speed, decreased significantly when gait changed to a run, and were assumed to provide the necessary input to signal a gait transition, fulfilling the requirements of the first three criteria, but only ankle angular velocity reached a critical level before the transition, satisfying all four criteria to be considered a determinant of the PTS.
A Biomechanical Review of the Techniques Used to Estimate or Measure Resistive Forces in Swimming
Authors: Sacilotto Gina B.D. , Ball Nick , Mason Bruce R.
Published: March 2014

Resistive or drag forces encountered during free swimming greatly influence the swim performance of elite competitive swimmers. The benefits in understanding the factors which affect the drag encountered will enhance performance within the sport. However, the current techniques used to experimentally measure or estimate drag values are questioned for their consistency, therefore limiting investigations in these factors. This paper aims to further understand how the resistive forces in swimming are measured and calculated. All techniques outlined demonstrate both strengths and weaknesses in the overall assessment of free swimming. By reviewing all techniques in this area, the reader should be able to select which one is best depending on what researchers want to gain from the testing.
Frontal Plane Running Biomechanics in Female Runners With Previous Iliotibial Band Syndrome
Authors: Foch Eric , Milner Clare E.
Published: March 2014

Proximal factors such as excessive frontal plane pelvis and trunk motion have been postulated to be biomechanical risk factors associated with iliotibial band syndrome. In addition, lateral core endurance deficiencies may be related to increased pelvis and trunk motion during running. The purpose of this cross-sectional investigation was to determine if differences in biomechanics during running, as well as lateral core endurance exist between female runners with previous iliotibial band syndrome and controls. Gait and lateral core endurance were assessed in 34 female runners (17 with previous iliotibial band syndrome). Multivariate analysis of variance was performed to assess between group difference in pelvis, trunk, hip, and knee variables of interest. Runners with previous iliotibial band syndrome exhibited similar peak trunk lateral flexion, peak contralateral pelvic drop, peak hip adduction, and peak external knee adduction moment compared with controls. In addition, trunk-pelvis coordination was similar between groups. Contrary to our hypotheses, both groups exhibited trunk ipsilateral flexion. Lateral core endurance was not different between groups. These findings provide the first frontal plane pelvis and trunk kinematic data set in female runners with previous iliotibial band syndrome. Frontal plane pelvis and trunk motion may not be associated with iliotibial band syndrome.
DNA Repair Pathway Gene Expression Score Correlates with Repair Proficiency and Tumor Sensitivity to Chemotherapy
Authors: Pitroda Sean P. , Pashtan Itai M. , Logan Hillary L. , Budke Brian , Darga Thomas E. , Weichselbaum Ralph R. , Connell Philip P.
Published: March 2014

Measuring DNA repair pathway choice determines the sensitivity of cancers to individual classes of treatment.
Whole-Genome Sequencing in Newborn Screening Programs
Authors: Knoppers Bartha M. , Sénécal Karine , Borry Pascal , Avard Denise
Published: March 2014

The possible introduction of whole-genome sequencing into newborn screening programs should proceed with caution.
Author Response to Comment on “Drug Discovery: Turning the Titanic”
Authors: Zerhouni Elias A.
Published: March 2014

In the face of poorly understood disease complexity, a diversity of approaches is the best strategy.