bluuebunny/crossref_metadata_2025 huggingface dataset:
Indirect Intelligent Sliding Mode Control Using Hysteretic Recurrent Neural Networks With Application to a Shape Memory Alloy Actuated Beam
Authors: Hannen Jennifer C. , Buckner Gregory D.
Published: July 2013

This paper presents the development of an indirect intelligent sliding mode controller (IISMC) for shape memory alloy (SMA) actuators. The controller manipulates applied voltage, enabling temperature control in one or more SMA tendons, which are offset to produce bending in a flexible beam tip. Hysteresis compensation is achieved using a hysteretic recurrent neural network (HRNN), which maps the nonlinear, hysteretic relationships between SMA temperatures and bending angle. Incorporating this HRNN into a variable structure control architecture provides robustness to model uncertainties and parameter variations. Single input, single output and multivariable implementations of this control strategy are presented. Controller performance is evaluated using a flexible beam deflected by single and antagonistic SMA tendons. Experimental results demonstrate precise tracking of a variety of reference trajectories for both configurations, with superior performance compared to an optimized PI controller for each system. Additionally, the IISMC demonstrates robustness to parameter variations and disturbances.
Conductivity-Based Damage Detection in Carbon Fiber Composites
Authors: Loyola Bryan R. , Arronche Luciana , La Saponara Valeria , Loh Kenneth J.
Published: July 2013

Fiber-reinforced polymer (FRP) composites have become a primary structural material in many new structures, particularly in the aerospace, wind turbine, automobile, and marine industries, due to their higher strength-to-weight ratios, corrosion resistance, and ease of manufacturing. However, these composite materials have complex damages modes that are different from typical monolithic metallic alloys, such as delamination, fiber breakage, matrix cracking, and fiber-matrix debonding. These avenues of damage tend to manifest internally to the composite structure, making them nearly invisible to visual inspection. Several damage detection approaches have been introduced for the purpose of in situ non-destructive evaluation (NDE) of composites; however, many of these approaches require complex analysis methods, data interpolation for achieving spatial sensing, and/or embedding invasive sensors into the composites themselves. To allow for widespread implementation of a next-generation NDE approach for composites, an easily discernible, highly visual, and fast approach that does not adversely affect the structural performance of the composite laminate is needed. This study introduces the use of a spatially distributed electrical conductivity distribution mapping method called electrical impedance tomography (EIT). EIT reconstructs a material’s 2D or 3D electrical conductivity within a series of boundary electrodes. A 100 mA current is injected between two opposing electrodes while the adjacent differential voltages are measured at the remaining electrodes; this process is repeated for all opposing electrode pairs. Using a linear reconstruction algorithm, changes in electrical conductivity are spatially resolved and plotted for easy detection, localization, and evaluation of damage. This approach is validated by applying EIT to a set of carbon fiber-reinforced polymer composite laminates. First, damage has been simulated in composite parts by selectively removing portions of the structure and then verifying that EIT has captured this occurrence. After validation of the EIT method, pristine composite laminates have been subjected to low velocity impact damage. Before and after impact EIT readings have been taken. The differential conductivity reconstruction is presented. This work demonstrates the value of adopting electrical impedance tomography for in situ NDE of FRP composites.
Analytical and Numerical Modelling of Shape Memory Alloy Negator Springs for Long-Stroke Constant-Force Actuators
Authors: Spaggiari Andrea , Dragoni Eugenio
Published: July 2013

This paper explores the merits of shape memory Negator springs as powering elements for solid state actuators. A Negator spring is a spiral spring made of strip of metal wound on the flat with an inherent curvature such that, in repose, each coil wraps tightly on its inner neighbour. The unique characteristic of Negator springs is the nearly-constant force needed to unwind the strip for very large, theoretically infinite deflections. Moreover the flat shape, having a high area over volume ratio, grants improved bandwidth compared to any solution with solid wires or helical springs. The SMA material is modelled as elastic in austenitic range while an exponential continuum law is used to describe the martensitic behaviour. The mathematical model of the mechanical behaviour of SMA Negator springs is provided and their performances as active elements in constant-force, long-stroke actuators are assessed.

The SMA Negator spring is also simulated in a commercial finite element software, ABAQUS, and its mechanical behaviour is estimated through FE analyses. The analytical and the numerical prediction are in good agreement, both in martensitic and in austenitic range.
Evaluation of Encapsulated IPMC Sensor Based on Thick Parylene Coating
Authors: Lei Hong , Li Wen , Zhu Guoming , Tan Xiaobo
Published: July 2013

Ionic polymer-metal composites (IPMCs) have intrinsic sensing and actuation capabilities. However, IPMCs require ionic hydration to operate. As the most commonly used solvent, water content contained in the polymer changes with the humidity level of the ambient environment, which affects the sensing behavior of an IPMC in air. Motivated by the need to ensure consistent sensing performance of IPMCs under different ambient environments, in this paper we propose thick (up to 10 micrometers) parylene C coating for IPMC sensors, develop effective coating processes, and evaluate the stability of the encapsulated sensors in air. During the process of parylene coating, water molecules would evaporate inside the deposition chamber, resulting in the encapsulated IPMCs’ losing sensing capability. To address this challenge and control the hydration level of an encapsulated IPMC, the proposed fabrication process comprises major steps of parylene deposition, water absorption, and SU-8 seal. The influence of hydration level controlled by the water absorption step is studied to improve the sensitivity of the IPMC sensor. The water impermeability of the proposed encapsulation technique is tested in different media. Experiments have also been conducted to evaluate the performance of the encapsulated IPMC sensor. The sensing consistency and the lifetime of an encapsulated sensor in air are studied in an environment with changing humidity, along with the comparison with an uncoated IPMC sensor. Experimental results show that the proposed thick parylene coating can effectively maintain the water content inside the IPMC and reduce the interference due to the ambient humidity change, which allows IPMC sensors to be used in many practical applications.
On the Functional Characteristics of Adaptive Resetting of Shape Memory Actuators in the Field of Automotive Applications
Authors: Czechowicz Alexander , Langbein Sven
Published: July 2013

Shape memory alloys (SMA) are thermally activated smart materials. Due to their ability to change into a previously imprinted actual shape by means of thermal activation, they are suitable as actuators for mechatronical systems. Despite the advantages shape memory alloy actuators provide (lightweight-actuators, lower costs etc.), these elements are seldom integrated by engineers into automotive systems. One reason for this phenomenon is among others the varying dynamic behavior at different ambient temperatures. A methodical approach through the problem definition as well as the presentation of different solutions using adaptive resetting introduces experimental results on the behavior of these actuator systems. The publication presents different solutions as well as long-time experiments compared to conventional SMA actuators at automotive conditions.
Finite Amplitude Underwater Flexural Vibrations of Cantilevers
Authors: Aureli Matteo , Porfiri Maurizio
Published: July 2013

We study flexural vibrations of a thin rectangular cross section cantilever beam submerged in a quiescent viscous fluid. The cantilever is subject to base excitation and undergoes oscillations whose amplitude is comparable with its width. The structure is modeled as an Euler-Bernoulli beam and the fluid-structure interaction is captured through a nonlinear complex-valued hydrodynamic function which accounts for added mass and fluid damping. Results from a parametric 2D computational fluid dynamics analysis of an oscillating rigid lamina, representative of a generic beam cross section, are used to establish the dependence of the hydrodynamic function on the governing flow parameters. It is found that, as the frequency and amplitude of the vibration increase, vortex shedding and convection phenomena are enhanced, thus promoting nonlinear hydrodynamic damping. We derive a computationally efficient reduced order modal model for beam oscillations incorporating the non-linear hydrodynamic function and we validate theoretical results against experiments on underwater vibrations flexible beams.
Modelling of Needle Domains in Barium Titanate Single Crystals Using Dislocation Theory
Authors: Sui Dan , Huber John E.
Published: July 2013

A model is established to study needle domains in barium titanate single crystals using the theory of dislocations. Considering the mechanical and electrical compatibility in ferroelectrics, the fields produced by a needle domain are represented using the equivalent fields due to an effective edge dislocation coupled with a line charge. Accordingly, the dislocation fields derived by Barnett and Lothe for anisotropic piezoelectric media are used to analyze the stress and electric fields around needle domains.

The interaction of the pairs of needle domains in an infinite piezoelectric body is studied by computing the interactive force and the total energy. It is found that the needle tip interactions tend to be dominated by the electrostatic terms. Additionally, comb-like arrays of needle domains are investigated. Stable configurations of needle domains in a herringbone pattern are identified, consistent with experimental evidence. However, comb-like arrays of needles are found to be unstable if perfectly insulating conditions without lattice friction are assumed.
New Insights Into Piezoelectric Energy Harvesting Using a Dynamic Magnifier
Authors: Gibert James M. , Alazemi Saad , Paige Frederick E. , Daqaq Mohammed F.
Published: July 2013

This manuscript considers the design and performance of a piezoelectric vibration-based energy harvester with a dynamic magnifier (VEHDM) to a traditional single degree-of-freedom harvester (VEHS) using proper metrics. Past research has shown that the addition of the second magnifying mass can increase the peak power harvested by as much as 20 times [1] when compared to the VEHS; however, the metrics of performance comparison were not clearly defined, nor was the comparison carried at optimal loading conditions. For instance, the peak power was compared at different excitation frequencies and power not power per unit mass is used for comparison purposes. Additionally, the VEHDM is designed so that the magnifier mass and stiffness are considered independent of the primary stiffness and mass of the harvester. In this study, we determine the optimal properties of the magnifier, in terms of frequency ratios and resistance that maximizes both power and power density for a fixed frequency harmonic excitation. The optimized VEHDM is compared to a similarly optimized VEHS. Treating the magnifier as a tuned mass damper (TMD), i.e., simply adding the magnifying mass and stiffness to the optimized VEHS and then tuning the magnifier to split the resonance peak of the single mass harvester, increases the peak power harvested for mass ratios greater than one. However, the peak frequencies of excitation of the VEHS and VEHDM differ. Only at large values of the mass ratio does the excitation frequency of the VEHS and VEDHM coincide, making the VEHDM less efficient in terms of power per unit mass. Similarly, simply adding a magnifying stiffness and mass to the optimized VEHS and then tuning both the VEDHM to the VEHS’s to the same excitation frequency by changing the the uncoupled natural frequency of VEHDM’s magnifier components limits the performance of the VEDHM. In this case, the VEHDM generates the same amount of power as the VEHS. Nonetheless, the VEHS is more efficient in terms of power generated per unit mass. In order to match the single mass harvester’s power per unit mass, the optimal magnifier for the VEHDM is a rigid spring of negligible mass acting in series with the stiffness with the VEHDM’s piezoceramic element. However, significant gains in both peak power and peak power per unit mass for a fixed frequency excitation can be obtained by considering all the mass and stiffness elements in the VEHDM, while using the same piezoelectric in the VEHS.
Characterization of Shape-Changing Panels With Embedded Rubber Muscle Actuators
Authors: Peel Larry D. , Molina Enrique , Baur Jeff , Justice Ryan
Published: July 2013

There is great interest in making shape-changing aircraft structures that are more biomimetic. Cylindrical McKibben-like flexible actuators efficiently convert fluid pressure into mechanical energy and thus offer excellent force-to-weight ratios while behaving similar to biological muscle. McKibben-like Rubber Muscle Actuators (RMAs) were embedded into elastomer panels. The effect of actuator spacing on the performance of these shape-changing panels was investigated. The work included nonlinear finite element analysis, fabrication, and testing of panels where four RMAs were spaced side-by-side, 1/2, 1, and 1.3 RMA diameters apart.

Nonlinear “Laminated Plate” and “Rod & Plate” finite element models of individual RMAs were created from existing RMA dimensions. After adjusting for an initial “activation pressure,” the models produced realistic RMA forces. The laminated plate models used less computer resources, but only produced small amounts of actuator contraction (actuator strain). The more resource-intensive Rod & Plate models better replicated fiber/braid re-orientation and produced axial strains up to 60% of test values. Three types of embedded RMA panel FEA models; a “2D Cross-Section,” a “Full 3D Panel” (with either Laminated Plate or Rod & Plate RMAs) and a “3D Unit Cell” (also with either Laminated Plate or Rod & Plate RMAs). The Full 3D Rod & Plate model gave the most accurate strains and forces, but required unsustainable levels of computing resources. The 2D cross-section model predicted optimal RMA spacing to be at 1 diameter. All other FEA models show optimal panel performance between 1/2 and 1 diameter spacing.

Panels with embedded RMAs were fabricated and tested with air or water pressure. Panel force as a function of pressure and as a function of contraction (strain) was obtained.

Overall, FEA and test results for panels indicate that optimal performance occurs when the RMAs are spaced between 1/2 to 1 diameter apart. Actuator force as a function of spacing is fairly flat in this region, indicating that minor design or manufacturing differences may not significantly affect performance. However, the total amount of axial contraction decreases significantly at greater than optimal spacing. Useful design, simulation, and test methodologies for embedded RMA panels have been demonstrated.
Combined Modeling of Bilayer Networks for Sensing Applications
Authors: Freeman Eric C. , Philen Michael K. , Leo Donald J.
Published: July 2013

The bilayer lipid membrane (BLM) is a naturally occurring thin layer of phospholipid molecules that surrounds cellular systems. The membrane operates as a near-impermeable barrier allowing for the generation of membrane potentials across the layer through changes in ionic concentrations. This membrane is required for regular cell function ranging from storing energy to passing signals. Engineering advancements have allowed for the rapid creation of artificial bilayer membranes, and these membranes are currently considered for many biomimetic applications.

The application of interest for this paper is the further development of these cellular systems for sensing applications. This will be accomplished through a combined fluid-bilayer model, allowing for study of the bilayer transduction properties at both high and low frequencies. Several approaches are discussed and applied to multiple cell systems with or without embedded voltage-dependent ion pores. Finally the results are studied and evidence is presented for the development of a new molecular model for cellular systems combining chemical, electrical, and mechanical stimuli.
The Homogenized Energy Model for Characterizing Magnetization and Strains in Ferromagnetic Materials
Authors: Van Blaircum Lucus , Smith Ralph C.
Published: July 2013

Ferromagnetic materials exhibit rate-dependent hysteresis, creep and constitutive nonlinearities due to their inherent domain structure. For model-based control applications, these non-linear attributes must be incorporated in a models in a manner that facilitates model calibration and real-time control implementation. In this paper, we present a homogenized energy model for these materials. This is a multiscale framework that quantifies energy at the domain level and then employs stochastic homogenization techniques to provide macroscopic models that are highly efficient to implement. The accuracy of models will be validated using a variety of experimental data.
Stable Bipedal Locomotion Using Biomimetic IPMC Actuators
Authors: Hosseinipour Milad , Elahinia Mohammad
Published: July 2013

Ionic conducting polymer-metal composites (abbreviated as IPMC) are interesting actuators that can act as artificial muscles in robotic and microelectromechanical systems. The electrochemical-mechanical behavior of these materials has been modeled by various black or gray box models. In this study, the governing partial differential equation of the behavior of IPMC is solved using finite element methods to find the critical actuation parameters such as strain distribution, maximum strain, and response time. 1D results of the FEM solution are then extended to 2D to find the tip displacement of a flap actuator. Model of a seven-degree of freedom biped robot, actuated by IPMC flaps, is then introduced to study. Possibility of fast and stable bipedal locomotion using IPMC artificial muscles is the main motivation of this study. Taking the actuator limits into account, joint path trajectories are generated to achieve a fast and smooth motion. The stability of the proposed gait is then evaluated using ZMP criterion and motion simulation. Fabrication parameters of each actuator such as length, platinum (or gold) plating thickness and installation angle are also studied using the generated trajectories.
A Geometrically Bio-Inspired MFC Actuator for Wrinkle Control of Kapton Membranes
Authors: Fleurent-Wilson Eric , Ibrahim Mohammed , Salehian Armaghan
Published: July 2013

Vital components of inflatable antenna structures in light-weight satellites, Kapton© membranes, are prone to wrinkling due to high thermal gradients experienced in space; resulting in a decrease in performance. Simple, robust and compact actuators are required for automated removal of localized wrinkling in these membranes. Leveraging the large force and small displacement of Macro-Fibre Composites (MFCs) by mimicking the mechanics of the ciliary muscle in the human optical system, an actuator was designed and experimentally tested in the control of localized wrinkling of Kapton© in tension. Three configurations were built and tested utilizing M-5887-P1 MFC units. The force-displacement relationships were determined through testing. The control logic and circuit were developed. The actuator proved successful in local membrane wrinkling experiments. It was shown that by leveraging the high force and low displacement of MFCs a reliable actuator can be developed to effectively eliminate localized wrinkles in Kapton© membranes for space applications.
Guided Wave Based Fatigue Crack Detection and Localization in Aluminum Aerospace Structures
Authors: Hensberry Kevin , Kovvali Narayan , Liu Kuang C. , Chattopadhyay Aditi , Papandreou-Suppappola Antonia
Published: July 2013

The work presented in this paper provides an insight into the current challenges to detect incipient damage in complex metallic structural components. The goal of this research is to improve the confidence level in diagnosis and damage localization technologies by developing a robust structural health management (SHM) framework. Improved methodologies are developed for reference-free localization of fatigue induced cracks in complex metallic structures. The methodologies for damage interrogation involve damage feature extraction using advanced signal processing tools and a probabilistic approach for damage detection and localization. Specifically, piezoelectric transducers are used in pitch-catch mode to interrogate the structure with guided Lamb waves. A novel time-frequency (TF) based signal processing technique based on the matching pursuit decomposition (MPD) algorithm is developed to extract time-of-flight damage features from dispersive guided wave sensor signals, followed by a Bayesian probabilistic approach used to optimally fuse multi-sensor information and localize the crack tip. The MPD algorithm decomposes a signal using localized TF atoms and can provide a highly concentrated TF representation. The Bayesian probabilistic framework enables the effective quantification and management of uncertainty. Experiments are conducted to validate the proposed detection and localization methods. Results presented will illustrate the usefulness of the developed approaches in detection and localization of damage in aluminum lug joints.
mTORC1 Phosphorylation Sites Encode Their Sensitivity to Starvation and Rapamycin
Authors: Kang Seong A. , Pacold Michael E. , Cervantes Christopher L. , Lim Daniel , Lou Hua Jane , Ottina Kathleen , Gray Nathanael S. , Turk Benjamin E. , Yaffe Michael B. , Sabatini David M.
Published: July 2013

Not mTORCing

Inhibition of the protein kinase complex mTORC1 has potentially beneficial therapeutic affects that include inhibition of cancer and extension of life span. However, effects of its inhibition in vivo have sometimes been disappointing. One reason may be that the well-studied inhibitor of mTORC1, rapamycin, inhibits some effects of mTORC1 but not others. In line with this idea,

Kang
et al.

(
1236566
) show that the effect of rapamycin depends on the substrate. Characteristics of the phosphorylation sites on various substrates caused them to be phosphorylated with different efficiency by mTORC1. The substrates that were most efficiently phosphorylated were resistant to inhibition of mTORC1. The results explain how various sites, sometimes within the same protein, can differ in their sensitivity to rapamycin.
Proton Conduction with Metal-Organic Frameworks
Authors: Shimizu George K. H. , Taylor Jared M. , Kim SiRim
Published: July 2013

Further development of microporous crystalline materials as proton conductors may lead to better electrolyte membranes for fuel cells.
Science Signaling
Podcast: 23 July 2013
Authors: Davis Daniel M. , VanHook Annalisa M.
Published: July 2013

The distribution of an inhibitory receptor on the surface of natural killer cells changes upon engagement of an activating receptor.
Citrulline and Epithelial Identity
Authors: Foley John F.
Published: July 2013

In the nucleus, modification of N-terminal arginine residues of glycogen synthase kinase-3β to citrulline prevents the epithelial-to-mesenchymal transition.
Preventing Newborn Infection with Maternal Immunization
Authors: Black Steven , Margarit Immaculada , Rappuoli Rino
Published: July 2013

Scientists met in Siena to conceive strategies for preventing often-fatal group B streptococcal disease in newborns.
An Inferiority Complex for Chemo
Authors: Oliver Trudy G.
Published: July 2013

A drug combination without chemotherapy can cure leukemia patients with fewer toxic side effects.
Science Translational Medicine
Podcast: 24 July 2013
Authors: Langley Raymond , Smith Orla
Published: July 2013

Our most recent podcast is a conversation with Raymond J. Langley, who explains how a new molecular signature improves mortality prediction in patients with sepsis.
Use of Cell-Free Circulating Schistosome DNA in Serum, Urine, Semen, and Saliva To Monitor a Case of Refractory Imported Schistosomiasis Hematobia
Authors: Kato-Hayashi Naoko , Yasuda Mitsuko , Yuasa Jozi , Isaka Shigeo , Haruki Kosuke , Ohmae Hiroshi , Osada Yoshio , Kanazawa Tamotsu , Chigusa Yuichi
Published: July 2013

This case of imported refractory schistosomiasis has highlighted the usefulness of cell-free parasite DNA as a diagnostic marker to assess active schistosome infection. In contrast to the rapid disappearance of ova in urine, parasite DNA remained persistent in several other specimen types even after the fourth treatment with praziquantel. This result was consistent with the presence of morphologically intact ova in bladder biopsy samples and with the corresponding symptoms.
Discrimination of Enterohemorrhagic Escherichia coli (EHEC) from Non-EHEC Strains Based on Detection of Various Combinations of Type III Effector Genes
Authors: Delannoy Sabine , Beutin Lothar , Fach Patrick
Published: July 2013

Enterohemorrhagic
Escherichia coli
(EHEC) strains comprise a subgroup of Shiga-toxin (Stx)-producing
E. coli
(STEC) and are characterized by a few serotypes. Among these, seven priority STEC serotypes (O26:H11, O45:H2, O103:H2, O111:H8, O121:H19, O145:H28, and O157:H7) are most frequently implicated in severe clinical illness worldwide. Currently, standard methods using
stx
,
eae
, and O-serogroup-specific gene sequences for detecting the top 7 EHEC serotypes bear the disadvantage that these genes can be found in non-EHEC strains as well. Here, we explored the suitability of
ureD
,
espV
,
espK
,
espN
,
Z2098
, and
espM1
genes and combinations thereof as candidates for a more targeted EHEC screening assay. For a very large panel of
E. coli
strains (
n
= 1,100), which comprised EHEC (
n
= 340), enteropathogenic
E. coli
(EPEC) (
n
= 392), STEC (
n
= 193), and apathogenic strains (
n
= 175), we showed that these genetic markers were more prevalent in EHEC (67.1% to 92.4%) than in EPEC (13.3% to 45.2%), STEC (0.5% to 3.6%), and apathogenic
E. coli
strains (0 to 2.9%). It is noteworthy that 38.5% of the EPEC strains that tested positive for at least one of these genetic markers belonged to the top 7 EHEC serotypes, suggesting that such isolates might be Stx-negative derivatives of EHEC. The associations of
espK
with either
espV
,
ureD
, or
Z2098
were the best combinations for more specific and sensitive detection of the top 7 EHEC strains, allowing detection of 99.3% to 100% of these strains. In addition, detection of 93.7% of the EHEC strains belonging to other serotypes than the top 7 offers a possibility for identifying new emerging EHEC strains.
Characterization of a Novel Picornavirus Isolate from a Diseased European Eel (
Anguilla anguilla
)
Authors: Fichtner Dieter , Philipps Anja , Groth Marco , Schmidt-Posthaus Heike , Granzow Harald , Dauber Malte , Platzer Matthias , Bergmann Sven M. , Schrudde Daniela , Sauerbrei Andreas , Zell Roland
Published: July 2013

A novel picornavirus was isolated from specimens of a diseased European eel (
Anguilla anguilla
). This virus induced a cytopathic effect in eel embryonic kidney cells and high mortality in a controlled transmission study using elvers. Eel picornavirus has a genome of 7,496 nucleotides that encodes a polyprotein of 2,259 amino acids. It has a typical picornavirus genome layout, but its low similarity to known viral proteins suggests a novel species in the family
Picornaviridae
.
THE GRANITE PROBLEM AND THE METHOD OF MULTIPLE PREJUDICES
Authors: BOWEN NORMAN L.
Published: July 2013

INTRODUCTION

In his well-known essay, The method of multiple working hypotheses, Chamberlin (1897) discussed various modes of attack upon scientific problems. Of a theory hastily advanced in explanation of any group of observations he said, “From an unduly favored child it readily grows to be a master and leads its author whithersoever it will.” The theory thus becomes a “ruling theory.” It might be said that it becomes a prejudice. As we may readily suppose, he regarded the ruling theory as having little to commend it, though he did point out that in the method of the ruling theory the investigator’s “very errors may indeed stimulate investigation on the part of others.” Chamberlin then passed on to consider the method of the working hypothesis, which he naturally regarded as having notable advantages, but added “. . . the distinction is not such as to prevent a working hypothesis from gliding with the utmost ease into a ruling theory. . . ”, and further, “To avoid this grave danger the method of multiple working hypotheses is urged” where “the mutual conflicts of hypotheses whet the discriminative edge of each.” Chamberlin thus had in mind a happy situation where an individual investigator diligently sought all reasonable processes that might lead to an observed relation, carefully considered the full consequences of each process envisioned, impartially compared these deduced consequences with the re-examined facts and thus reached a conclusion as to the probable process or group of processes that were operative. ‘Tis a consummation . . .
Bilateral macrostomia
Authors: Mohan Ravi Prakash Sasankoti , Verma Sankalp , Agarwal Neha , Singh Udita
Published: July 2013

Macrostomia as a rare facial deformity is classified among facial clefts. It is a rare congenital anomaly which affects the aesthetics and function of the oral cavity. It is usually associated with deformities of other structures developed from the first and second branchial arches. Bilateral transverse cleft occurring alone is uncommon. Here we report a case of bilateral macrostomia (bilateral lip cleft) in a 5-year-old girl as a sole entity without other skeletal and facial deformities.
Getting Scotland on the move? Reflections on a 5-year review of Scotland's national physical activity strategy
Authors: Halliday Emma , Mutrie Nanette , Bull Fiona
Published: July 2013

The public health risks of physical inactivity have led many national governments to develop policies that aim to increase population levels of physical activity. There is however, little evidence available about the effectiveness of such strategies and physical activity leaders may also face challenges in securing sufficient levels of political will and lasting investment for physical activity. This article reports on a review of a national physical activity strategy in Scotland after 5 years of implementation and offers lessons that may assist policymakers, practitioners and communities seeking to mobilise political commitment and leadership for physical activity in their own countries.
Factors mediating HIV risk among female sex workers in Europe: a systematic review and ecological analysis
Authors: Platt Lucy , Jolley Emma , Rhodes Tim , Hope Vivian , Latypov Alisher , Reynolds Lucy , Wilson David
Published: July 2013

Objectives

We reviewed the epidemiology of HIV and selected sexually transmitted infections (STIs) among female sex workers (FSWs) in WHO-defined Europe. There were three objectives: (1) to assess the prevalence of HIV and STIs (chlamydia, syphilis and gonorrhoea); (2) to describe structural and individual-level risk factors associated with prevalence and (3) to examine the relationship between structural-level factors and national estimates of HIV prevalence among FSWs.

Design

A systematic search of published and unpublished literature measuring HIV/STIs and risk factors among FSWs, identified through electronic databases published since 2005. ‘Best’ estimates of HIV prevalence were calculated from the systematic review to provide national level estimates of HIV. Associations between HIV prevalence and selected structural-level indicators were assessed using linear regression models.

Studies reviewed

Of the 1993 papers identified in the search, 73 peer-reviewed and grey literature documents were identified as meeting our criteria of which 63 papers provided unique estimates of HIV and STI prevalence and nine reported multivariate risk factors for HIV/STI among FSWs.

Results

HIV in Europe remains low among FSWs who do not inject drugs (<1%), but STIs are high, particularly syphilis in the East and gonorrhoea. FSWs experience high levels of violence and structural risk factors associated with HIV, including lack of access to services and working on the street. Linear regression models showed HIV among FSWs to link with injecting drug use and imprisonment.

Conclusions

Findings show that HIV prevention interventions should be nested inside strategies that address the social welfare of sex workers, highlighting in turn the need to target the social determinants of health and inequality, including regarding access to services, experience of violence and migration. Future epidemiological and intervention studies of HIV among vulnerable populations need to better systematically delineate how microenvironmental and macroenvironmental factors combine to increase or reduce HIV/STI risk.
Comprehensive abortion care: evidence of improvements in hospital-level indicators in Tigray, Ethiopia
Authors: Prata Ndola , Bell Suzanne , Gessessew Amanual
Published: July 2013

Objective

Approximately 18% of maternal deaths in East Africa is attributable to unsafe abortion. Availability of comprehensive abortion care (CAC) services at all levels of the healthcare system, including medical abortion, has the potential to increase access to safe abortion thereby reducing the burden of unsafe abortion. This study sought to assess trends in abortion-related morbidity indicators in referral hospitals.

Design

Researchers conducted a secondary data analysis on retrospectively collected data.

Methods

Data analysed were collected from four hospitals in the Tigray region of Ethiopia that took part in a CAC pilot project. Providers were trained in mid-2009 to provide abortion services using all available technologies. Data records from hospitals were collected in 2012 for the years 2006 through 2012; 2006/2007 data were too sparse to include in the analyses.

Results

Trends in abortion-related services show a significant decrease in treatment of incomplete abortion, inverting the relationship between safe terminations and treatment of incompletes as a percentage of total abortions. Medication abortion was nearly non-existent in 2008, but increased steadily, representing 80% of total procedures in 2012. The inclusion of medication abortion and availability of CAC also contributed to a decline in inpatient procedures and prevalence of complications.

Conclusions

The trends observed in the data demonstrate how increased availability of CAC services at all levels of the healthcare system, among other factors, can contribute to reductions in the burden of unsafe abortion at referral hospitals.
Daily electronic self-monitoring of subjective and objective symptoms in bipolar disorder—the MONARCA trial protocol (MONitoring, treAtment and pRediCtion of bipolAr disorder episodes): a randomised controlled single-blind trial
Authors: Faurholt-Jepsen Maria , Vinberg Maj , Christensen Ellen Margrethe , Frost Mads , Bardram Jakob , Kessing Lars Vedel
Published: July 2013

Introduction

Electronic self-monitoring of affective symptoms using cell phones is suggested as a practical and inexpensive way to monitor illness activity and identify early signs of affective symptoms. It has never been tested in a randomised clinical trial whether electronic self-monitoring improves outcomes in bipolar disorder. We are conducting a trial testing the effect of using a Smartphone for self-monitoring in bipolar disorder.

Methods

We developed the MONARCA application for Android-based Smartphones, allowing patients suffering from bipolar disorder to do daily self-monitoring—including an interactive feedback loop between patients and clinicians through a web-based interface. The effect of the application was tested in a parallel-group, single-blind randomised controlled trial so far including 78 patients suffering from bipolar disorder in the age group 18–60 years who were given the use of a Smartphone with the MONARCA application (intervention group) or to the use of a cell phone without the application (placebo group) during a 6-month study period. The study was carried out from September 2011. The outcomes were changes in affective symptoms (primary), social functioning, perceived stress, self-rated depressive and manic symptoms, quality of life, adherence to medication, stress and cognitive functioning (secondary and tertiary).

Analysis

Recruitment is ongoing.

Ethics

Ethical permission has been obtained.

Dissemination

Positive, neutral and negative findings of the study will be published.

Registration details

The trial is approved by the Regional Ethics Committee in The Capital Region of Denmark (H-2-2011-056) and The Danish Data Protection Agency (2013-41-1710). The trial is registered at ClinicalTrials.gov asNCT01446406.
VACUUM FLUCTUATION CORRECTIONS TO MAXWELL ELECTRODYNAMICS REVISITED
Authors: TOMAZELLI J. L. , ZANELLATO D. E.
Published: July 2013

The influence of an external electromagnetic field on the vacuum structure of a quantized Dirac field is investigated by considering the quantum corrections to classical Maxwell's Lagrangian density induced by fluctuations of the nonperturbative vacuum. Effective Lagrangian densities for Maxwell's theory in (3 + 1) and (2 + 1) dimensions are derived from the vacuum zero-point energy of the fermion field in the context of a consistent Pauli–Villars–Rayski subtraction scheme, recovering Euler–Kockel–Heisenberg and Maxwell–Chern–Simons effective theories. Effective Scalar Quantum Electrodynamics is also discussed.
STRUCTURE AND MAGNETIC PROPERTIES OF NANOCRYSTALLINE (Fe50Co50)73.5Cu1Nb3Si13.5B9 ALLOYS
Authors: WANG YUXIN , JU YING , LU WEI , YAN BIAO , GAO WEI
Published: July 2013

( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 amorphous ribbons, a type of Co doped Finemet alloy, were prepared by melt-spinning and annealed at 440–560°C for 30 min. Influences of heat treatment and Co content on the crystallization were analyzed through differential scanning calorimetric (DSC) and X-ray diffractometry (XRD). The microstructure was analyzed by atomic force microscopy (AFM). The magnetic properties of ( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 and Finemet ribbons were tested by an alternating current soft magnetic properties measurement system. A comparative study of frequency dispersion properties between ( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 and Finemet was conducted. Results indicate that the optimal magnetic property has been achieved when ( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 ribbons were annealed at the temperature range of 480°C–520°C, after which the grain size became between 10 nm and 20 nm. Although the permeability of ( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 is not as high as that of Finemet, this Co -doped Finemet amorphous alloy presents better high frequency properties, and therefore is a promising candidate for the high frequency field applications.
COMBINATORIAL DEGREE BOUND FOR TORIC IDEALS OF HYPERGRAPHS
Authors: GROSS ELIZABETH , PETROVIĆ SONJA
Published: July 2013

Associated to any hypergraph is a toric ideal encoding the algebraic relations among its edges. We study these ideals and the combinatorics of their minimal generators, and derive general degree bounds for both uniform and non-uniform hypergraphs in terms of balanced hypergraph bicolorings, separators, and splitting sets. In turn, this provides complexity bounds for algebraic statistical models associated to hypergraphs. As two main applications, we recover a well-known complexity result for Markov bases of arbitrary 3-way tables, and we show that the defining ideal of the tangential variety is generated by quadratics and cubics in cumulant coordinates.
ACCURATE NONLINEAR REGISTRATION FOR TWO-DIMENSIONAL GEL ELECTROPHORESIS IMAGES
Authors: XIN HUA-MEI , ZHU YUEMIN
Published: July 2013

Two-dimensional gel electrophoresis (2DGE) images are an important support for the analysis of proteins in proteomics. The registration of 2DGE images is considered as one of key elements in protein identification while it is a difficult problem. This paper proposes a new accurate nonlinear registration approach for 2DGE images, based on the exploitation of both spot distance measure and spot intensity. The method consists of three steps: multi-resolution affine registration, spot pairing and thin-plate spline interpolation. The results on both simulated and real gel images show that the proposed method significantly improves registration accuracy in comparison with thin-plate spline registration techniques.
TORTUOSITY–POROSITY RELATIONSHIP IN TWO-DIMENSIONAL FRACTAL MODEL OF POROUS MEDIA
Authors: FERANIE SELLY , LATIEF FOURIER D. E.
Published: July 2013

Tortuosity (τ) of two-dimensional fractal model of porous media is investigated to study their relationship with porosity. Square full-walk technique is applied to obtain τ in a two-dimensional fractal model of porous substance constructed by Randomized Sierspinski Carpets. The numerical result is in good agreement with previous results and empirical relation between tortuosity and porosity given by τ ~ p(1 - ϕ) + 1 that was found by other using Lattice Gas Automata method for solving flow equation on two-dimensional porous substance constructed by randomly placed rectangles of equal size and with unrestricted overlap. Average tortuosity of the flow path decreases linearly as fractal dimension of pore increases at each fractal iteration. Both fractal dimension and iteration give almost the same linearly tortuosity–porosity relation. The type of random algorithm for constructing Randomized Sierspinski Carpets has no significant influence on the tortuosity–porosity relation.
SEPARATING PRINCIPLES BELOW RAMSEY'S THEOREM FOR PAIRS
Authors: LERMAN MANUEL , SOLOMON REED , TOWSNER HENRY
Published: July 2013

In recent years, there has been a substantial amount of work in reverse mathematics concerning natural mathematical principles that are provable from RT, Ramsey's Theorem for Pairs. These principles tend to fall outside of the "big five" systems of reverse mathematics and a complicated picture of subsystems below RT has emerged. In this paper, we answer two open questions concerning these subsystems, specifically that ADS is not equivalent to CAC and that EM is not equivalent to RT.
The emplacement of a large, chemically zoned, rheomorphic, lava-like ignimbrite: the Sgurr of Eigg Pitchstone, NW Scotland
Authors: Brown David J. , Bell Brian R.
Published: July 2013

The Sgurr of Eigg Pitchstone on the Isle of Eigg, NW Scotland, is a crystal-rich, trachydacitic, partially vitrophyric rock, which has previously been interpreted both as a lava and as a sill. We interpret this rock as a chemically zoned, rheomorphic, lava-like ignimbrite that formed during a sustained pyroclastic eruption. The Sgurr of Eigg Pitchstone can be subdivided into discrete emplacement units distinguished by the following features: (1) their present-day weathering characteristics; (2) the orientation, spacing and morphology of the columnar joints; (3) sharp, undulating boundaries with marked topographic breaks. The absence of weathered surfaces, palaeosols, pyroclastic fall deposits or sedimentary rocks at emplacement unit boundaries suggests deposition from a single eruption. The emplacement units, some of which display upper and basal vitrophyres, represent distinct depositional packages that record several rapidly emplaced ignimbrites, which welded, cooled and devitrified as a simple, essentially single, cooling unit, during eruption from a sustained, low pyroclastic column. The Sgurr of Eigg Pitchstone displays a pervasive base-parallel flow banding, which is folded into intrafolial recumbent isoclinal folds. The flow banding and folds indicate that rheomorphism occurred throughout deposition. The Sgurr of Eigg Pitchstone is interpreted as an erosional remnant of an extensive ignimbrite sheet, the first such unit recorded within the North Atlantic Igneous Province.
Coverage algorithms for visual sensor networks
Authors: Munishwar Vikram P. , Abu-Ghazaleh Nael B.
Published: July 2013

Visual sensor networks (VSNs) are becoming increasingly popular in a number of application domains. A distinguishing characteristic of VSNs is to self-configure to minimize the need for operator control and to improve scalability. One of the areas of self-configuration is camera coverage control that is, how should cameras adjust their field-of-views to cover maximum targets? This is an NP-hard problem. We show that the existing heuristics have a number of weaknesses that influence both coverage and overhead. Therefore, we first propose a computationally efficient centralized heuristic that provides near-optimal coverage for small-scale networks. However, it requires significant communication and computation overhead, making it unsuitable for large-scale networks. Thus, we develop a distributed algorithm that outperforms the existing distributed algorithm with lower communication overhead, at the cost of coverage accuracy. We show that the proposed heuristics guarantee to cover at least half of the targets covered by the optimal solution. Finally, to gain benefits of both centralized and distributed algorithms, we propose a hierarchical algorithm where cameras are decomposed into neighborhoods that coordinate their coverage using an elected local coordinator. We observe that the hierarchical algorithm provides scalable near-optimal coverage with networking cost significantly less than that of centralized and distributed solutions.
Trade-off between energy efficiency and report validity for mobile sensor networks
Authors: Fu Huai-Lei , Lin Phone , Fang Yuguang , Wang Ting-Yu
Published: July 2013

Mobile sensor networks (MSNs) have been widely deployed to provide a ubiquitous solution to real-time monitoring applications such as traffic data collection in vehicular ad-hoc networks (VANETs), ocean data collection in underwater sensor networks (UWSNs), and biodata collection in wireless body area networks (WBANs). One major issue for designing MSNs is the energy-validity trade-off, that is, the trade-off between the energy efficiency for mobile sensors (MSs) and the validity of sensing reports. In this article, we propose a novel mechanism,
Energy-Efficient Distributedly Controlled Reporting
(E
2
DCR), to mitigate the energy consumption for MSs in real-time monitoring applications while keeping the sensing report valid. In this mechanism, we design
dynamic sleeping adjustment
(DSA) algorithms to adjust an MS's sleeping period using a heuristic method to reduce energy consumption. We provide analytical models to evaluate the performance of E
2
DCR in terms of the power savings and report validity. It has been shown that with E
2
DCR, MSs can report with less energy consumption while satisfying delay constraints for real-time monitoring applications.