bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust Position Control of a Quadrotor Using Onboard Optical Flow Sensor
Authors: Lu Qi , Ren Beibei , Parameswaran Siva , Zhong Qing-Chang
Published: February 2017

In this paper, the uncertainty and disturbance estimator (UDE)-based position controllers are developed to achieve the robust position control of a quadrotor using only onboard sensing. Firstly, in order to accurately estimate the positions of the quadrotor in GPS-denied environments, an open source high speed optical flow sensor PX4FLOW is adopted. Secondly, the UDE-based controllers are developed to handle the challenges brought by the highly nonlinear quadrotor position dynamics, including underactuation, coupling, nonaffine inputs, model uncertainties and external disturbances. Real flight experiments, including hover and disturbance rejection are carried out to demonstrate the effectiveness of the developed UDE-based controllers.
An Adaptive Feedforward Control Approach for Rejecting Disturbances Acting on Uncertain Linear Systems
Authors: Shahsavari Behrooz , Pan Jinwen , Horowitz Roberto
Published: February 2017

This paper proposes a novel adaptive feedforward control method for rejecting unknown disturbances acting on linear systems with uncertain dynamics. The proposed algorithm does not require a model of the plant dynamics and does not use batches of measurements in the adaptation process. Moreover, it is applicable to both minimum and non-minimum phase plants. The algorithm is a “direct” adaptive method, in the sense that the identification of system parameters and the control design are performed simultaneously. In order to verify the effectiveness of the proposed method, an adaptive feedforward controller is designed as an add-on compensator to the existing baseline controller of a hard disk drive. An accelerometer mounted on the disk drive casing provides the input signal for the controller. The control objective is to minimize the standard deviation of the position error signal in the presence of external random vibrations. Simulation results show that reduction of 46% in the standard deviation of the position error signal can be obtained.
Deflection Control of Electrostatically Actuated Micro Cantilevers via Fuzzy Controller
Authors: Khadembashi Mohammad , Moeenfard Hamid , Ghasemi Amir H.
Published: February 2017

The objective of this paper is to develop a novel two-level supervised fuzzy controller to stabilize the response of electrostatically actuated microbeams beyond their pull-in range. To this end, Lagrange equations are utilized to derive the differential equations governing the dynamic behavior of the system. To investigate the possibility of using a passive control strategy, the static behavior of the system is studied in detail. Through some open loop simulations, the qualitative and quantitative dependence of the beam deflection to the applied voltage and system parameters are studied. Based on the understanding obtained from these studies, a single level fuzzy controller is designed to control the response of the microstructure. In order to enhance the performance of the closed-loop system, another higher level supervisory fuzzy controller is designed to tune the maximum allowable voltage the lower level controller can apply. Simulation results reveal that both single level and multi-level fuzzy controllers can extend the travel range of the microbeams beyond its pull-in range. However the rise time, overshoot and settling time in the multilevel controlled system is far better than that of a simple single level fuzzy controller. The novel controller presented in this paper can be applied in most intrinsically nonlinear nano/micro structures to help them to have more efficient regulations and command tracking maneuvers.
A Generalized Anti-Windup Scheme Considering Amplitude and Rate Saturations
Authors: Zhou Shiying , Zheng Minghui , Tomizuka Masayoshi
Published: February 2017

The secondary actuator in dual-stage hard disk drives (HDDs) is subject to both amplitude and rate saturations. This paper proposes an anti-windup scheme based on robust control methodologies by modeling the saturations as bounded nonlinear uncertainties. The scheme is constructed as an add-on linear conditioning structure which consists of a dual-input-dual-output filter. With the proposed scheme, the induced l2 norm from the disturbance to the position error is minimized with guaranteed stability. Loop transformations to reduce redundant uncertainties and weighting functions to accommodate different performances are discussed. Simulation validation on a dual-stage HDD system is performed and the effectiveness of the proposed anti-windup scheme is demonstrated.
A Control Framework for Anthropomorphic Biped Walking Based on Stabilizing Feedforward Trajectories
Authors: Rezazadeh Siavash , Gregg Robert D.
Published: February 2017

Although dynamic walking methods have had notable successes in control of bipedal robots in the recent years, still most of the humanoid robots rely on quasi-static Zero Moment Point controllers. This work is an attempt to design a highly stable controller for dynamic walking of a human-like model which can be used both for control of humanoid robots and prosthetic legs. The method is based on using time-based trajectories that can induce a highly stable limit cycle to the bipedal robot. The time-based nature of the controller motivates its use to entrain a model of an amputee walking, which can potentially lead to a better coordination of the interaction between the prosthesis and the human. The simulations demonstrate the stability of the controller and its robustness against external perturbations.
Advanced Manual System Identification Using Lead and Lag Compensators With Complex Poles and Zeros
Authors: Echols-Jones Piers M. , Dokukin Maxim E. , Sokolov Igor , Messner William C.
Published: February 2017

Automated methods for deriving dynamic models from frequency response data of high-order dynamics systems are the default choice of most engineers. However, these methods themselves often require manual tuning of weighting parameters, a priori selection of system order, and even by hand removal of extraneous dynamics. On the other hand, manually matching complicated features in the Bode plot of the frequency response of high-order system is difficult with conventional first and second order numerators and denominators. In this papers we present a manual technique for systematically creating a dynamic model from Bode plots of frequency response data with complicated features. We apply the method to identifying dynamics of a piezoelectric stage holding the sample of an atomic force microscope (AFM). We show the manual method works better than the tfest command of Matlab™ for this example system.
Modeling, Hardware-in-the-Loop Simulations and Control Design for Small-Scale Vertical Axis Wind Turbines
Authors: Onol A. O. , Sancar U. , Onat A. , Yesilyurt S.
Published: February 2017

In this study, we present a methodology for the assessment of overall performance for vertical axis wind turbines (VAWT) with straight blades. Salient features of our approach include a validated computational fluid dynamics (CFD) model and a hardware-in-the loop (HIL) test-bed. The two-dimensional, time-dependent CFD model uses the k-ε turbulence model and is coupled with the dynamics of the rotor involving friction and generator torques. The power coefficient curve for the rotor is obtained from the CFD simulations by varying the generator torque over time, and then used in the HIL test-bed that consists of an electrical motor, a gearbox, a permanent magnet synchronous generator, and an electronic load. In this setup, the VAWT rotor is mimicked by the electrical motor based on a power coefficient curve obtained from CFD simulations. Effects of the electrical conversion and control design on the overall performance of the VAWT are studied in the HIL setup. Additionally, a simple non-linear control (SNC) algorithm that mimics a model predictive controller and two different adaptations of the maximum power point tracking (MPPT) algorithm with fixed and variable step-sizes are designed and implemented in HIL simulations. According to results, the generator has a profound effect on the overall power output and the efficiency of the turbine; and the SNC and MPPT algorithms perform satisfactorily under step wind conditions.
A Physics-Based Control-Oriented Model for the Turbine Power of a Variable-Geometry Turbo-Charger
Authors: Song Kang , Upadhyay Devesh , Zeng Tao , Sun Harold
Published: February 2017

In this paper, we discuss the development of a control-oriented model for the power developed by a Variable Geometry Turbine (VGT). The turbine exit flow velocity, Cex, is obtained based on a polytropic process assumption for the full turbine stage. The rotor inlet velocity, Cin, is estimated, through an empirical relationship between Cex and Cin as a function of a dimensionless parameter ψ. The turbine power is developed based on Euler’s equations of Turbomachinery under the assumptions of zero exit swirl and alignment between the nozzle orientation and the Cin velocity vector. A power loss sub-model is also designed to account for the transmission loss associated with the power transfer between the turbine and compressor. The loss model is an empirical model and accounts for bearing friction and windage losses. Model validation results, for both steady state and transient operation, are shown.
Miniature Underwater Robotic Fish for Animal-Robot Interactions
Authors: Phamduy Paul , Vazquez Miguel , Rizzo Alessandro , Porfiri Maurizio
Published: February 2017

Research in animal behavior has benefited from the availability of robots able to elicit controllable, customizable, and versatile stimuli in behavioral studies. For example, biologically-inspired robotic fish can be designed to mimic the morphophysiology of predators and conspecifics to study fear response and sociality. However, size is a critical limitation of the existing arrays of robotic fish. Here, we present the design of a miniature robotic fish for future animal-robot interaction studies featuring a novel application of multi-material three-dimensional (3D) printing and utilizing a solenoid for actuation. The use of multi-material printing enables a skeletal design of only two parts, while retaining the complete functionality of larger prototypes enclosing requisite electronics and incorporating an active joint for propulsion. Parametric tests are conducted to test the swimming speed of the robotic fish and a compact dynamic model with two degrees of freedom to elucidate swimming of the robotic fish is presented.
Nonlinear Dynamics of Upright Human Balance While Using a Passive-Cane
Authors: Chagdes James R. , Freire Joao P. , Shukla Amit
Published: February 2017

Recent mathematical models of human posture have been explored to better understand the space of control parameters that result in stable upright balance. These models have demonstrated that there are two types of instabilities — a leaning instability and an instability leading to excessive oscillation. While these models provide insight into the stability of upright bipedal stance, they are not sufficient for individuals that require the aid of assistive technologies, such as a passive-cane or a walker. Without a valid model one is unable to understand the control parameters required for maintain upright posture or if similar instabilities even exist when assistive technologies are used. Therefore in this study, we developed a mathematical model of human posture while using a passive-cane to examine the nonlinear dynamics of stance. First, we developed a simple mathematical model of cane assisted human stance by adapting the inverted pendulum model of Chagdes et al., [1]. We modeled the human body, upper arm, forearm, cane, and ground as a two-degree-of-freedom, five-bar-linkage with pin joints representing the ankle, shoulder, elbow, and wrist joints. Second, we investigate upright stability in the parameter space of feedback gain and time-delay. We hypothesize that the analysis will show similar instabilities compared to that of a human standing without assistive technology. We also hypothesize that the space of control parameters which stabilize upright equilibrium posture will increase when a cane is incorporated. This study has two potential applications. First, the developed mathematical model could allow clinicians to better assess technology assisted balance and if needed help clinicians to customize a treatment plan for an individual that allows them to avoid unstable postural dynamics. Second, the mathematical model can be used to design customized assistive technology for people of difference physical properties and impairments.
Li-Ion Cell Aging Model Online Parameter Estimation for Improved Prognosis
Authors: Tulpule Punit , Chang Chin-Yao , Rizzoni Giorgio
Published: February 2017

In this paper, a semi-empirical aging model of lithium-ion pouch cells containing blended spinel and layered-oxide positive electrodes is calibrated using aging campaigns. Sensitivity analysis is done on this model to identify the effect of parameter variations on the State of Health (SOH) prediction. The sensitivity analysis shows that the aging model alone is not robust enough to perform long term predictions, hence we propose to use online parameter estimation algorithms to adapt the model parameters. Four different estimation methods are compared using aging campaign. It is demonstrated that the estimation algorithms improve aging model leading to significant improvement in Remaining Useful Life (RUL) prediction.
Time-Optimal Trajectories for Steered Agent With Constraints on Speed and Turning Rate
Authors: Scott William Lewis , Leonard Naomi Ehrich
Published: February 2017

Through application of Pontryagin’s maximum principle we derive minimum-time optimal trajectories for a “steered particle” agent with constraints on speed and turning rate to reach a point on the plane with free terminal heading. We also present a formulation of the optimal trajectories in the form of a state-feedback control law that is applicable to real time motion planning on a robotic system with these motion constraints.
Development of a Multiple Axis Robotic Platform for Ankle Studies
Authors: Nalam Varun , Lee Hyunglae
Published: February 2017

This paper describes the design, development, modeling, and control of a robotic platform developed for the characterization of mechanical impedance and reflex responses of the ankle in 2 degrees-of-freedom (DOF): sagittal (dorsiflexion-plantarflexion) and frontal plane (inversion-eversion). The platform, controlled actively along both DOFs, is capable of producing rapid and strong perturbations up to an angular speed of 200°/s and peak torque of 400 Nm. This enables study of ankle impedance characteristics even during extreme task conditions such as running. The platform is designed to provide perturbations to the ankle up to an angle of 20° in sagittal plane and 10° in frontal plane, which is sufficient for all possible configurations of the ankle during postural balance and stance phase of walking. These characteristics of the platform make it ideal for both impedance and reflex characterization along both DOFs of the ankle. The platform’s performance of position control is validated under varying loads simulating various conditions of posture and locomotion. The platform’s orientation accuracy in both sagittal and frontal planes is established for various input signals including slow sinusoid inputs and rapid ramp perturbations. Implications for future ankle studies to estimate neuro-mechanical characteristics and applications to assistive and prosthetic devices are discussed.
Arbitrary-Order Iterative Learning Control Considering H∞ Synthesis
Authors: Zheng Minghui , Wang Cong , Sun Liting , Tomizuka Masayoshi
Published: February 2017

Iterative learning control (ILC) is an effective technique to improve the tracking performance of systems through adjusting the feedforward control signal based on the memory data. It is critically important to design the learning filters in the ILC algorithm that assures the robust stability of the convergence of tracking errors from one iteration to next. The design procedure usually involves lots of tuning work especially in high-order ILC. To facilitate this procedure, this paper proposes an approach to design learning filters for an arbitrary-order ILC with guaranteed convergence and ease of tuning. The filter design problem is formulated into an H∞ optimal control problem. This approach is based on an infinite impulse response (IIR) system and conducted directly in iteration-frequency domain. Important characteristics of the proposed approach are explored and demonstrated on a simulated wafer scanning system.
An Artificial Brain Mechanism to Develop a Learning Paradigm for Robot Navigation
Authors: Sarim Mohammad , Schultz Thomas , Kumar Manish , Jha Rashmi
Published: February 2017

Advancement in solid state device technology has made it possible to replicate some learning behaviors on those devices as observed in biological neurons. A very widely used mechanism of learning is Spike Timing Dependent Plasticity (STDP) to realize an unsupervised learning process. In this work, we have developed a novel solution for learning using such networks in robots that can be implemented on novel resistive memory devices. This artificial brain mechanism is capable of learning by observing the environment and taking actions to achieve a desired goal. We have demonstrated this learning scheme using a mathematical model representing the reconfiguration of strengths in synapses. This model can be easily implemented on miniaturized microprocessors using resistive crossbar memories. The reconfigurable resistive memory devices in crossbar arrays are capable of mimicking the synapses in human brains by changing their resistances on application of appropriate voltage signal. In this work, we have demonstrated the potential of this learning scheme by applying it to navigate a two-wheeled differential drive robot in an environment cluttered with obstacles. It can be observed that the robot is able to navigate the environment autonomously, and can reach a given target while avoiding obstacles.
Near Energy Optimal Control Allocation for Dual-Input Over-Actuated Systems
Authors: Duan Molong , Okwudire Chinedum
Published: February 2017

This paper proposes a method for near energy optimal allocation of control effort in dual-input over-actuated systems using a linear time-invariant (LTI) controller. The method assumes a quadratic energy cost functional, and the non-causal energy optimal control ratio within the redundant actuation space is defined. Near energy optimal control allocation is addressed by using a LTI controller to align the control inputs with a causal approximation of the energy optimal control ratio. The use of a LTI controller for control allocation leads to low computation burden compared to techniques in the literature which require optimization at each time step. Moreover, the proposed method achieves broadband, near optimal control allocation, as opposed to traditional allocation methods which make use of a static system model for control allocation. The proposed method is validated through simulations and experiments on an over-actuated hybrid feed drive system. Significant improvements in energy efficiency without sacrificing positioning performance are demonstrated.
Experimental Gait Analysis of Waveboard Locomotion
Authors: Agrawal Ayush , Zaini Hesham M. , Dear Tony , Choset Howie
Published: February 2017

Through modeling and experimentation, we analyze common gaits on a waveboard, an underactuated mechanical system whose motion is governed by both nonholonomic constraints and momentum conservation. We take advantage of the system’s symmetries to derive a reduced system model that differentiates between kinematic and dynamic components of motion. We evaluate this model using marker trajectory data gathered through an optical tracking system for various types of gaits. By extracting relevant trajectory parameters via state reconstruction and fitting our joint variables to an ellipse, we determine the kinematic components of gaits commonly used by human riders. In particular, we demonstrate that traditional forward motion is purely dynamic, while sustained turning motion contains kinematic components. In order to validate our model, we compare experimentally obtained trajectories with reconstructed displacements based on the model. Finally, we suggest an approach for further analysis of the dynamic components of these gaits.
On the localization of high-frequency, sinusoidally amplitude-modulated tones in free field
Authors: Macaulay Eric J. , Rakerd Brad , Andrews Thomas J. , Hartmann William M.
Published: February 2017

Previous headphone experiments have shown that listeners can lateralize high-frequency sine-wave amplitude-modulated (SAM) tones based on interaural time differences in the envelope. However, when SAM tones are presented to listeners in free field or in a room, diffraction by the head or reflections from room surfaces alter the modulation percentages and change the shapes of the envelopes, potentially degrading the envelope cue. Amplitude modulation is transformed into mixed modulation. This article presents a mathematical transformation between the six spectral parameters for a modulated tone and six mixed-modulation parameters for each ear. The transformation was used to characterize the stimuli in the ear canals of listeners in free-field localization experiments. The mixed modulation parameters were compared with the perceived changes in localization attributable to the modulation for five different listeners, who benefited from the modulation to different extents. It is concluded that individual differences in the response to added modulation were not systematically related to the physical modulation parameters themselves. Instead, they were likely caused by individual differences in processing of envelope interaural time differences.
The clone wars
Authors: Beltran Himisha
Published: February 2017

Genome sequencing of patients with pancreatic adenocarcinoma reveals high concordance of driver alterations across metastases.
Membrane Remodeling by a Bacterial Phospholipid-Methylating Enzyme
Authors: Danne Linna , Aktas Meriyem , Unger Andreas , Linke Wolfgang A. , Erdmann Ralf , Narberhaus Franz
Published: February 2017

Membrane deformation by proteins is a universal phenomenon that has been studied extensively in eukaryotes but much less in prokaryotes. In this study, we discovered a membrane-deforming activity of the phospholipid
N
-methyltransferase PmtA from the plant-pathogenic bacterium
Agrobacterium tumefaciens
. PmtA catalyzes the successive three-step
N
-methylation of phosphatidylethanolamine to phosphatidylcholine. Here, we defined the lipid and protein requirements for the membrane-remodeling activity of PmtA by a combination of transmission electron microscopy and liposome interaction studies. Dependent on the lipid composition, PmtA changes the shape of spherical liposomes either into filaments or small vesicles. Upon overproduction of PmtA in
A. tumefaciens
, vesicle-like structures occur in the cytoplasm, dependent on the presence of the anionic lipid cardiolipin. The N-terminal lipid-binding α-helix (αA) is involved in membrane deformation by PmtA. Two functionally distinct and spatially separated regions in αA can be distinguished. Anionic interactions by positively charged amino acids on one face of the helix are responsible for membrane recruitment of the enzyme. The opposite hydrophobic face of the helix is required for membrane remodeling, presumably by shallow insertion into the lipid bilayer.

IMPORTANCE
The ability to alter the morphology of biological membranes is known for a small number of some bacterial proteins. Our study adds the phospholipid
N
-methyltransferase PmtA as a new member to the category of bacterial membrane-remodeling proteins. A combination of
in vivo
and
in vitro
methods reveals the molecular requirements for membrane deformation at the protein and phospholipid level. The dual functionality of PmtA suggests a contribution of membrane biosynthesis enzymes to the complex morphology of bacterial membranes.
Clinical management of electrical burns in the developing world: a case of electrical burn injury left untreated leading to amputation
Authors: Choong Marcus , Chy Delia , Guevarra Jerric R , Ross Allen G
Published: February 2017

We discuss the case of a 26-year-old male patient from Northern Samar, the Philippines who was left without essential health services after the amputation of all four limbs following a high voltage (20 000 volts) injury in Metro Manila in 2011. Local health services in the developing world are faced with enormous challenges in providing first-line care for burn patients. The cost of maintaining a burn unit, finding suitable qualified staff, and appropriate referral mechanisms are only some of the challenges faced. Once a patient is discharged from hospital they face more obstacles in obtaining artificial limbs, physiotherapy and access to mental health services. Disability pensions are non-existent thus patients place a considerable lifelong burden on their families.
Association of passive and active smoking with self-rated health and life satisfaction in Iranian children and adolescents: the CASPIAN IV study
Authors: Heshmat Ramin , Qorbani Mostafa , Safiri Saeid , Eslami-Shahr Babaki Amir , Matin Nassim , Motamed-Gorji Nazgol , Motlagh Mohammad-Esmaeil , Djalalinia Shirin , Ardalan Gelayol , Mansourian Morteza , Asayesh Hamid , Kelishadi Roya
Published: February 2017

Objective

To assess the joint association of passive and active smoking with self-rated health and life satisfaction among Iranian children and adolescents.

Methods

Using a multistage random cluster sampling method, a representative sample of 14 880 school students were selected from urban and rural areas of 30 provinces of Iran. Data were gathered using a questionnaire, a weight scale and metre. Participants were classified into four groups based on their smoking patterns: ‘non-smoker’, ‘only active smoker’, ‘only passive smoker’ and ‘active and passive smoker’. Life satisfaction (LS) and self-rated health (SRH) were assessed by self-administered validated questionnaires based on the WHO-Global School-based student Health Survey (WHO-GSHS). Data were analysed using a t-test, χ2test and multiple logistic regression.

Results

A total of 13 486 individuals (6640 girls and 6846 boys) out of 14 880 invited participated in the study (response rate 90.6%). LS and good SRH showed linearly negative associations with smoking status in both sexes. The proportions of LS and SRH categories were significantly different among all subsets of smoking status. Those classified as ‘non-smokers’ had the highest proportions of LS and good SRH, followed by ‘only passive smokers’ and ‘only active smokers’, while those with ‘active and passive smoking’ had the lowest proportions of LS and good SRH. In a multivariate model, students in the ‘active and passive smoking’ group had lower odds of LS (OR 0.43; 95% CI 0.32 to 0.57) and good SRH (OR 0.51; 95% CI 0.38 to 0.68) than those in the ‘non-smoker’ group. Students in the ‘only passive smoker’ group also had lower odds of LS (OR 0.75; 95% CI 0.67 to 0.83) and good SRH (OR 0.72; 95% CI 0.66 to 0.80) compared with the ‘non-smoker’ group.

Conclusions

Adolescents with different smoking habits and exposure patterns have poorer SRH and LS than non-smokers. Both active and passive smoking status could affect LS and SRH in adolescents. Therefore, smoking prevention strategies should be considered as a health priority in school health services for promoting psychological well-being in children and adolescents.
Healthcare experiences of patients with age-related macular degeneration: have things improved? Cross-sectional survey responses of Macular Society members in 2013 compared with 1999
Authors: Boxell Emily M , Amoaku Winfried M , Bradley Clare
Published: February 2017

Objective

To investigate healthcare experiences of patients with age-related macular degeneration (AMD) and determine whether a previous survey and Royal College of Ophthalmologists (RCOphth) management guidelines brought improvements.

Design

Cross-sectional survey of Macular Society members in 2013 compared with previous 1999 survey.

Setting

UK Postal Questionnaires.

Participants

1169 respondents in 2013 (1187 in 1999).

Intervention

Publication of 1999 survey results (2002), and RCOphth AMD guidelines (2009).

Main outcome measures

Respondents answered questions about experiences at diagnosis. Five questions were replicated from the 1999 survey for direct comparison in the 2013 survey which included additional questions based on 2009 RCOphth recommendations for information and support provision for patients with AMD.

Results

Most 2013 survey respondents were given the name of their macular condition (91%), felt the healthcare professional was interested in them (71%) and were satisfied overall with the diagnostic consultation (76%). These outcomes show significant improvement since 1999. Within the 2013 sample, multivariable analyses showed gradual trends of improvement over time in: provision of written information, Macular Society information and receiving appropriate help, support and advice at diagnosis. Only overall satisfaction with the diagnostic consultation (but not the other nine areas of information and support provision studied) significantly improved in the time after publication of the RCOphth 2009 guidelines. There were no significant improvements associated with the publication of the 1999 survey results. Low information and support provision remained, for example, 44% of respondents diagnosed after the RCOphth 2009 guidelines reported not receiving information on what to do if vision deteriorated. Lack of such information at diagnosis was significantly associated with registration as sight impaired (p<0.01). Reports of general practitioner (GP) knowledge of AMD remained low: 39% reported their GP was ‘not at all well informed’. The 2013 respondents reported lower levels of help and support from GPs than 1999 respondents (p<0.001).

Conclusions

Patients diagnosed with AMD after 1999 (vs before 1999) reported better experiences at diagnostic consultation. However, information and support provision at diagnosis, and satisfaction with GPs remained low.
Medical students' opportunities to participate and learn from activities at an internal medicine ward: an ethnographic study
Authors: Hägg-Martinell A , Hult H , Henriksson P , Kiessling A
Published: February 2017

Objectives

To optimise medical students’ early clerkship is a complex task since it is conducted in a context primarily organised to take care of patients. Previous studies have explored medical students’ perceptions of facilitation and hindrance of learning. However, the opportunities for medical student to learn within the culture of acute medicine care have not been fully investigated. This study aimed to explore how medical students approach, interact and socialise in an acute internal medicine ward context, and how spaces for learning are created and used in such a culture.

Design and setting

Ethnographic observations were performed of medical students' interactions and learning during early clerkship at an acute internal medicine care ward. Field notes were taken, transcribed and analysed qualitatively. Data analysis was guided by Wenger's theory of communities of practice.

Participants

21 medical students and 30 supervisors participated.

Results

Two themes were identified:Nervousness and curiosity—students acted nervously and stressed, especially when they could not answer questions. Over time curiosity could evolve. Unexplored opportunities to support students in developing competence to judge and approach more complex patient-related problems were identified.Invited and involved—students were exposed to a huge variation of opportunities to learn, and to interact and to be involved. Short placements seemed to disrupt the learning process. If and how students became involved also depended on supervisors' activities and students' initiatives.

Conclusions

This study shed light on how an acute internal medicine ward culture can facilitate medical students' possibilities to participate and learn. Medical students' learning situations were characterised by questions and answers rather than challenging dialogues related to the complexity of presented patient cases. Further, students experienced continuous transfers between learning situations where the potential to be involved differed in a wide variety of ways.
Understanding repeated non-attendance in health services: a pilot analysis of administrative data and full study protocol for a national retrospective cohort
Authors: Williamson Andrea E , Ellis David A , Wilson Philip , McQueenie Ross , McConnachie Alex
Published: February 2017

Introduction

Understanding the causes of low engagement in healthcare is a pre-requisite for improving health services’ contribution to tackling health inequalities. Low engagement includes missing healthcare appointments. Serially (having a pattern of) missing general practice (GP) appointments may provide a risk marker for vulnerability and poorer health outcomes.

Methods and analysis

A proof of concept pilot using GP appointment data and a focus group with GPs informed the development of missed appointment categories: patients can be classified based on the number of appointments missed each year. The full study, using a retrospective cohort design, will link routine health service and education data to determine the relationship between GP appointment attendance, health outcomes, healthcare usage, preventive health activity and social circumstances taking a life course approach and using data from the whole journey in the National Health Service (NHS) healthcare. 172 practices will be recruited (∼900 000 patients) across Scotland. The statistical analysis will focus on 2 key areas: factors that predict patients who serially miss appointments, and serial missed appointments as a predictor of future patient outcomes. Regression models will help understand how missed appointment patterns are associated with patient and practice characteristics. We shall identify key factors associated with serial missed appointments and potential interactions that might predict them.

Ethics and dissemination

The results of the project will inform debates concerning how best to reduce non-attendance and increase patient engagement within healthcare systems. Significant non-academic beneficiaries include governments, policymakers and medical practitioners. Results will be disseminated via a combination of academic outputs (papers, conferences), social media and through collaborative public health/policy fora.
Objective functional results in patients with knee osteoarthritis submitted to a 2-day educational programme: a prospective randomised clinical trial
Authors: Rezende Marcia Uchoa de , Farias Fabiane Elize Sabine de , Silva Cleidnéia Aparecida Clemente da , Cernigoy Claudia Helena de Azevedo , Camargo Olavo Pires de
Published: February 2017

Background

Although education is recommended for the treatment of knee osteoarthritis (KOA), its effectiveness in osteoarthritis (OA) remains low according to subjective questionnaires. The timed-up-and-go (TUG) and five-times-sit-to-stand tests (FTSST) reflect muscle strength and balance and could be used as objective measures of effectiveness.

Aim

To measure the effect of an educational programme in patients with KOA by TUG and FTSST and correlate these results to those of subjective questionnaires.

Methods

Prospective randomised controlled trial of patients with KOA. Participants (n=198) were allocated into four groups. Three groups participated in 2 days of lectures with 1 (group 1), 2 (group 2) and 3-month (group 3) intervals between classes. Group 4 had no classes. Participants were asked to exercise at least three times a week. Half of the patients from all groups received bimonthly telephone calls reinforcing diet and exercise instructions. All four groups received the printed and video material presented in the classes. At baseline and at 1 year after initial assessment, patients performed the FTSST and TUG and answered WOMAC, Lequesne, SF-36 and Visual Analogue Scale questionnaires.

Results

The TUG results did not change at 1 year follow-up, whereas FTSST improved (average difference of 4.66, p<0.001) irrespective of the implementation of classes or telephone calls. Both baseline and 1 year TUG and FTSST results correlated weakly (r<0.3) to the subjective functional, pain and quality of life results (p<0.001).

Conclusions

This educational programme improved function as determined by lower limb muscle strength (FTSST) irrespective of the patients’ subjective non-improvement.

Trial registration number

Clinical trials registration number:NCT01572051.

Level of evidence

Level 1A.
Systematic review of the effectiveness, barriers and facilitators to general practitioner engagement with specialist secondary services in integrated palliative care
Authors: Carmont Sue-Ann , Mitchell Geoffrey , Senior Hugh , Foster Michele
Published: February 2017

The general practitioner (GP) has a critical role in an integrated model of palliative care as they often know the patient and carer well, are experts in generalist care and have knowledge of health and social services in the community. Specialist palliative services have insufficient capacity to meet demand and those with non-cancer terminal conditions and those from rural and remote areas are underserved. Research has focused on improving access to palliative care by engaging the GP with specialist secondary services in integrated palliative care.

Objectives

(1) Evaluate the effectiveness of interventions designed to engage GPs and specialist secondary services in integrated palliative care; and (2) identify the personal, system and structural barriers and facilitators to integrated palliative care.

Method

MEDLINE, EMBASE and CINAHL were searched. Any study of a service that engaged the GP with specialist secondary services in the provision of palliative care was included. GP engagement was defined as any organised cooperation between the GP and specialist secondary services in the care of the patient including shared consultations, case conferences that involved at least both the GP and the specialist clinician and/or other secondary services, and/or any formal shared care arrangements between the GP and specialist services. The specialist secondary service is either a specialist palliative service or a service providing specialist care to a palliative population. A narrative framework was used to describe the findings.

Results

17 studies were included. There is some evidence that integrated palliative care can reduce hospitalisations and maintain functional status. There are substantial barriers to providing integrated care. Principles and facilitators of the provision of integrated palliative care are discussed.

Conclusions

This is an emerging field and further research is required assessing the effectiveness of different models of integrated palliative care.
M1 macrophages are required for murine cerebral aneurysm formation
Authors: Nowicki Kamil W , Hosaka Koji , Walch Frank J , Scott Edward W , Hoh Brian L
Published: February 2017

Introduction

Macrophages and neutrophils have been separately implicated in cerebral aneurysm formation. The interactions between different myeloid subsets and the contributions of macrophage phenotypes in these lesions over time are not known. The purpose of the study was to examine macrophage phenotypic changes in cerebral aneurysms.

Methods

We induced aneurysm formation in C57BL/6 mice and quantified contributions of M1 and M2 macrophages in aneurysm specimens with or without neutrophil blockade. In our aneurysm model, the left common carotid and right renal arteries were ligated, and mice were placed on a hypertensive high fat diet. One week later, stereotactic injection with elastase solution into the basal cisterns was performed. An angiotensin II secreting osmotic pump was implanted. The mice were then treated with anti-CXCL1 antibody or IgG control antibody. Animals were euthanized at 3 days, or 1 or 2 weeks. The circle of Willis was analyzed using immunohistochemistry for M1 and M2 macrophage phenotype contributions.

Results

Proinflammatory M1/M2 ratio increased in cerebral aneurysm formation over time, from 0.56 at 3 days to 1.75 at 2 weeks (p<0.0001). In contrast, anti-CXCL1 antibody blockade led to polarization towards an anti-inflammatory phenotype with an M1/M2 ratio of 0.95 at 2 weeks compared with IgG treated mice (p=0.0007).

Conclusions

CXCL1 dependent neutrophil inflammation appears to have an important role in macrophage polarization to M1 phenotype in cerebral aneurysm development.
A mechanistic study of anti-HIV activities of antifungal peptides
Authors: Omar Ruchi , Yadav Arpita
Published: February 2017

HIV patients are constantly at risk of developing internal fungal infection and are thus regularly prescribed antifungal medications. Several classes of antifungal agents have been developed to combat ever increasing cases of resistant strains of fungi. Azoles, despite being the most popular clinical choice, are not devoid of side effects. Many antimicrobial peptides have also been tested in search of safe, nontoxic antifungals but none succeeded as a commercial alternative. Recent research attempts show continued interest in these compounds and the complexities associated. Some experimental observations indicate involvement of these antimicrobial peptides in enhancing the efficacy of anti-HIV agents. We present here an intertwined approach to deal with two fatal diseases, internal fungal infection and HIV infection. Several naturally occurring antimicrobial peptides have been studied for their possible interaction with the viral RNA primer binding site (template) through interactions other than the base pair – base pair type. Peptides have been prepared and docked into viral template utilizing extra precision, flexible ligand docking. Implicit solvent was added around the complex and MMGBSA interaction energies were computed. Druggability aspects were explored by calculating ADME-related properties. A peptidomimetic compound has been strategically designed to introduce some druggability features in the peptide maintaining its viral template inhibition capability. The designed peptidomimetic lead compound may help in obtaining nontoxic anti-HIV agents in the future. This is the first study to suggest a plausible explanation for the anti-HIV activity of antifungal peptides at the molecular level and corroborate experimental findings of synergistic effects of these peptides on anti-HIV agents.
Combining data from bottom-trawl and acoustic-trawl surveys to estimate an index of abundance for semipelagic species
Authors: Kotwicki Stan , Ressler Patrick H. , Ianelli James N. , Punt André E. , Horne John K.
Published: February 2017

Fishery-independent surveys are useful for estimating abundance of fish populations and their spatial distribution. It is necessary in the case of semipelagic species to perform acoustic-trawl (AT) and bottom-trawl (BT) surveys to ensure that sampling encompasses both midwater and demersal components of the population. Abundance estimates from both survey types are negatively biased because of the blind zones associated with fish vertical distribution. These biases can vary spatially and temporally, resulting in confounded trends and additional variation in abundance estimates. To improve abundance estimates for semipelagic species we propose a new method for combining BT and AT survey data using environmental variables to predict the vertical overlap. Using walleye pollock (Gadus chalcogrammus) AT and BT surveys in the eastern Bering Sea as an example, we show that combined estimates provide more reliable whole water column and spatial distribution estimates than either survey can by itself. Although the combined estimates are still relative, they account for the uncertainty in the bias ratio between the two survey methods and the uncertainty associated with the extent of the water column sampled by both surveys. Our method of combining BT and AT data can be extended to other semipelagic species.
Flavor anomalies on the eve of the Run-2 verdict
Authors: Guadagnoli Diego
Published: February 2017

The [Formula: see text] measurement by LHCb suggests nonstandard Lepton-Universality Violation (LUV) to occur in [Formula: see text] decays with effects in muons rather than electrons. It is intriguing that a number of other measurements of [Formula: see text] transitions by LHCb and B-factories are consistent in magnitude and sign with the [Formula: see text] effect, and fit a coherent effective-theory picture. Further indications of nonstandard LUV are provided by the long-standing discrepancies in [Formula: see text] transitions via the ratios [Formula: see text] and [Formula: see text]. We review in detail the experimental situation and its rich outlook, the theoretical efforts — and their challenges — towards convincing dynamics beyond the effective-theory level, and discuss the many directions of further investigation that propagate from the current situation.
An Efficient Density-Based Algorithm for Data Clustering
Authors: Theljani Foued , Laabidi Kaouther , Zidi Salah , Ksouri Moufida
Published: February 2017

In this paper, we propose a novel density-based clustering method in which we deal with data appearing sequentially. In data mining, a cluster is a high-density region gathering a set of objects which are similar according to a prefixed criterion. For purposes of modelling, we restrict a cluster to be the contour of the region including these objects. The bounded contour function is obtained by applying a B-spline interpolation on the convex hull vertices enclosing the cluster. This procedure, named Cluster Domain Description (CDD), may give a realistic approximation of the cluster area. The clustering process is achieved afterwards with respect to the variation of the internal density of that area. In order to improve performances, a supplementary merge mechanism of evolving clusters is as well proposed. The method is assessed firstly on artificially generated data, and then on data extracted from a chemical system consisting of the Tennessee Eastman Process.
Preparation and biological evaluation of a carrier free 90yttrium labelled porphyrin as a possible agent for targeted therapy of tumor
Authors: Abedi Mahvash , Nabid Mohammad Reza , Shirvani-Arani Simindokht , Bahrami-Samani Ali , Vahidfar Nasim
Published: February 2017

In this research article, 5,10,15,20-tetrakis(phenyl)porphyrin (H2TPP) was produced and characterized. Then, radiolabeling of H2TPP was performed using the carrier free Y-90 which was prepared by the use of a home-made yttrium imprinted sorbent. The radiolabeling procedure was accomplished at 60 [Formula: see text] C during 12 h with a suitable radiochemical purity (95 ± 2% ITLC, 99 ± 0.5% HPLC) and specific activity of (1.0 ± 0.1 GBq/mmol). The obtained radio-labeled H2TPP in final formulation was kept for a week in order to investigate the complex stability. Accordingly, the partition coefficient was calculated as log [Formula: see text] 2.05. Furthermore, the biodistribution of the [Formula: see text]Y–TPP was determined in vital organs of normal wild-type rats using scarification studies. The kidneys could mostly remove the radio-complexes from the blood circulation and in less extends from the liver. As a result it is expected that due to its lipophilicity the higher mitochondrial and thus, tumor cell uptake of this radiolabeled porphyrin happens and therefore [Formula: see text]Y–TPP could act as an efficient potential agent for targeted therapy of tumor.