bluuebunny/crossref_metadata_2025 huggingface dataset:
Double circular ring compact antenna for ultra‐wideband applications
Authors: Khan Zakir , Razzaq Abdul , Iqbal Javed , Qamar Affaq , Zubair Muhammad
Published: July 2018

A simple, low‐cost and compact antenna is presented for ultra‐wideband applications. The proposed antenna design has improved characteristics as compared to the available different designs reported in the recent literature. The antenna is designed on FR4 substrate with microstrip feed line. Better results are obtained by optimising the geometrical parameters of patch and the lengths of ground and strip line. According to the criteria of −10 dB matching bandwidth, the designed antenna covers a high bandwidth ranging from 3.1 to 16 GHz. It was identified that the voltage to standing wave ratio is less than 2 which is also the desired characteristic for matching of an efficient antenna. The maximum dimension of this antenna is smaller than 0.27λ0 at the lowest frequency of operation, where λ0 is the free space wavelength. Further, low‐cost, smaller size and simple design of the proposed antenna makes it very suitable for biomedical applications.
Classes of non‐resonating‐node lowpass prototype networks suitable for realisation as evanescent‐mode waveguide bandpass filters
Authors: Fathelbab Wael M.
Published: July 2018

This work presents four classes of lowpass prototype networks comprising non‐resonating‐nodes (NRNs) realising generalised elliptic function transfer characteristics. Each class of networks can realise a maximum of (N − 2) finite‐frequency transmission zeros where N is the total number of the resonators in the network. The distinct feature pertinent to the proposed classes of networks is that they can be sub‐classed into two types: type I networks have positive frequency‐invariant elements (FIEs) located at the NRNs, and type II networks have negative FIEs located at the NRNs. type I networks are particularly suitable for the realisation as evanescent‐mode waveguide (EMW) bandpass filters which is the main subject of this work, whereas type II networks could be realised as waveguide bandpass filters operating above the cut‐off of the guide. Numerical examples of the four classes of the proposed networks are presented. The proposed circuit concepts are validated through the realisation of two classes of filters in EMW technology created utilising computer simulation technology (CST) microwave studio. The electrical performance of the CST filter structures and their circuit counterparts are in close agreement.
Broadband monopulse microstrip antenna array for X‐band monopulse tracking
Authors: Kumar Hemant , Kumar Girish
Published: July 2018

In this study, a broadband planar multilayer monopulse antenna at the X‐band for monopulse tracking applications is presented. A monopulse comparator has been designed using four hybrid ratrace for feeding the radiating elements of the antenna. Each radiating part of the monopulse antenna consists of 4 × 4 electromagnetically coupled microstrip antenna array. To achieve circular geometry as well as better side‐lobe level (SLL), a hybrid feeding technique is used in radiating antenna array by adding a few elements in series at the end elements of the parasitic layer of a 4 × 4 corporate fed array. The prototype has been fabricated, tested and measured results are compared with simulated results. The simulated impedance bandwidth for |S11| ≤ −10 dB is 21% (8.6–10.6 GHz). A measured peak sum beam gain of 24.4 dBi has been obtained. Measured SLL of <−15 dB has been achieved in both elevation and azimuth planes along with a null depth of <−35 dB for difference patterns in both the planes. The radiation pattern is symmetrical in both the planes with half‐power beamwidth nearly equal to 9.0°.
GaN‐HEMT asymmetric three‐way Doherty power amplifier using GPD
Authors: Koo Hyungmo , Kang Hyunuk , Lee Wooseok , Lee Hwiseob , Lee Kang‐Yoon , Hwang Keum Cheol , Yang Youngoo
Published: July 2018

A gallium‐nitride high electron mobility transistor (GaN‐HEMT) three‐way asymmetric Doherty power amplifier using an unequal three‐way Gysel power divider (GPD) is presented in this study. Considering the output power capacity of transistors, the peaking amplifier was designed to have an output power capacity that is 1.5 times larger than that of the carrier amplifier through the use of a parallel combination of two different power amplifiers. A peaking amplifier that is 1.5 times larger can provide a back‐off level of 7.5 dB for another peak efficiency. Two different power amplifiers in the peaking amplifier can work as a single power amplifier through an optimization of the input power division ratio (PDR). To split the input power for the carrier and the two peaking amplifiers, an unequal three‐way GPD with an optimized PDR was employed. The implemented Doherty power amplifier for the 2.14 GHz band exhibited a drain efficiency (DE) of 59.5% and an adjacent channel leakage ratio (ACLR) of 27.1 dBc at an average output power of 37.2 dBm (7.2 dB for the output power back‐off) for the 2.14 GHz downlink long‐term evolution signal, which has a peak‐to‐average power ratio of 6.5 dB and a signal bandwidth of 10 MHz.
Study on synchronisation capability enhancement of optoelectronic oscillator using dynamic control bandpass filter
Authors: Bishayee Kousik , Mandal Shantanu , Mukherjee Arindum , Biswas B. N. , Sarkar Chandan K.
Published: July 2018

This study introduces the concept of dynamic controlled bandpass filter (BPF) to achieve improved synchronisation capability of a single‐loop optoelectronic oscillator (OEO) under the effect of externally applied angle modulated signal. The governing equation for synchronisation ability of an OEO using dynamic control BPF has been derived. Theoretical study and comparison of locking capability enhancement using this dynamic BPF over a conventional static BPF are provided which is properly validated by simulation. Finally, the ability of frequency modulation to amplitude modulation conversion has been compared by measuring the total harmonic distortion values of the reconstructed signals.
Macro‐model of PV module and its application for partial shading analysis
Authors: Mao Zhang , Sunan Zhong , Peng Mao , Yanlong Sun , Weiping Zhang
Published: July 2018

Under partially shaded conditions (PSC), a photovoltaic (PV) array takes on more complex characteristics. It is very difficult and utterly necessary for PV system designers to understand and predict them. Other than the prevailing methodology of solving a set of non‐linear equations, the proposed methodology focuses on three key points of short circuit, MPP and open circuit. Besides, its V–I curve is split into three regions and replaced by three asymptote lines. From this viewpoint, this paper presents a novel Psim‐based piece‐wise linear macro‐model whose circuit parameter values are determined based on the foregoing three key points. The novel model, compared with the other published models, is characterised by short running time, relative high accuracy, and reliable unique solution. This model avoids the computational complexity and convergence issue. Furthermore, based on the novel model, an optimising configuration‐simulation model is presented for PV system designers to optimise PV array configurations under several given shaded patterns. Two new concepts of power and voltage reducing rate shall be introduced to estimate the PSC effect. The novel model and formulas, therefore, shall provide a good solution for studying the behavior of a large‐scale PV array in a complex scenario.
Distributed generation and energy storage system planning for a distribution system operator
Authors: Qiu Jing , Xu Zhao , Zheng Yu , Wang Dongxiao , Dong Zhao Yang
Published: July 2018

The smart distribution system architecture provides value‐based control techniques that facilitate bi‐directional power flows and energy transactions. Although consensus and understanding continue to develop around peer‐to‐peer transactions, a distribution system operator aims to promote and enable interoperability among entities, particularly those who own distributed energy resources such as energy storage system (ESS) and distributed generation (DG). In this study, the authors address the optimal allocation of ESS and DG in the smart distribution system architecture, in order to help the integration of wind energy. The formulated objective is to minimise the sum of the annualised investment cost, the expected profit and the imbalance cost in the two‐stage of power scheduling. The proposed model is verified on the modified IEEE 15‐bus distribution radial system. The simulation results have verified the proposed planning approach. Also, results show that a more risk‐seeking operation strategy is recommended if wind power penetration increases.
Inertial response characteristics analysis and optimisation of PMSG‐based VSG‐controlled WECS
Authors: Xi Jiangbei , Geng Hua , Ma Shaokang , Chi Yongning , Yang Geng
Published: July 2018

In this study, the inertial response characteristics of the permanent magnetic synchronous generator (PMSG)‐based wind energy conversion system (WECS) with different virtual synchronous generator (VSG) schemes are analysed and compared in detail. It is found that the dynamic coupling between the VSG active power control loop and the other control function, e.g. maximum power point tracking control and direct current bus voltage control, in VSG‐controlled WECS (WECS‐VSG) is inevitable. The coupling would result in the variations of the equivalent inertia constant and damping coefficient. The frequency support capability of the WECS‐VSG is thus weakened and the WECS‐VSG is even harmful to grid frequency support under some conditions. Besides, the requirement of the smooth energy recovery stage is usually put forward by the power system operator for the characteristics of the energy sources for inertial response (ESIRs) in WECS. To regain the expected synchronous generator alike inertial response characteristics and follow the ESIR property, a generalised optimal WECS‐VSG control strategy which can be embedded into different WECS‐VSG schemes is proposed and two examples for different ESIRs are designed. Finally, the effectiveness of the analysis and the proposed strategy are verified by simulation results.
Target recognition in SAR image based on robust locality discriminant projection
Authors: Yu Meiting , Zhang Siqian , Dong Ganggang , Zhao Lingjun , Kuang Gangyao
Published: July 2018

Extracting valuable and discriminative features is one of the crucial issues for target recognition in synthetic aperture radar (SAR) images. In this study, a feature extraction method based on robust locality discriminant projection (RLDP) is presented for SAR target recognition. To characterise the local structural information of SAR images, the manifold learning technique called the supervised locality preserving projection is introduced to learn a linear projection, with which the SAR image can be cast into an implicit feature space. Then, the authors extend t‐distributed stochastic neighbour embedding to a parametric framework for optimising the linear projection. In the resulting feature space, the intrinsic neighbour relation with a certain class can be preserved. In addition, the separation between different classes can be enhanced. Unlike most local manifold learning methods, the proposed method is robust to changes of the neighbour parameter. To further analyse the non‐linear structure, a useful variant of RLDP named kernel RLDP (KRLDP) is proposed. KRLDP exploits RLDP in an implicit reproducing kernel Hilbert space, where the kernel‐based non‐linear projection is learned to capture the non‐linear structural information. Extensive experiments on moving and stationary target automatic recognition databases demonstrate the effectiveness of the proposed methods.
Bio‐inspired processing of radar target echoes
Authors: Georgiev Krasin , Balleri Alessio , Stove Andy , Holderied Marc W.
Published: July 2018

Echolocating bats have evolved the ability to detect, resolve and discriminate targets in highly challenging environments using biological sonar. The way bats process signals in the receiving auditory system is not the same as that of radar and sonar and hence investigating differences and similarities might provide useful lessons to improve synthetic sensors. The Spectrogram Correlation And Transformation (SCAT) receiver is an existing model of the bat auditory system that takes into account the physiology and the neural organisation of bats that emit broadband signals. In this study, the authors present a baseband receiver equivalent to the SCAT that allows an analysis of target echoes at baseband. The baseband SCAT (BSCT) is used to investigate the output of the bat‐auditory model for two closely spaced scatterers and to carry out an analysis of range resolution performance and a comparison with the conventional matched filter. Results firstly show that the BSCT provides improved resolution performance. It is then demonstrated that the output of the BSCT can be obtained with an equivalent matched‐filter based receiver. The results are verified with a set of laboratory experiments at radio frequencies in a high signal‐to‐noise ratio.
On the total variation Wasserstein gradient flow and the TV-JKO scheme
Authors: Carlier Guillaume , Poon Clarice
Published: July 2018

We study the JKO scheme for the total variation, characterize the optimizers, prove some of their qualitative properties (in particular a form of maximum principle and in some cases, a minimum principle as well). Finally, we establish a convergence result as the time step goes to zero to a solution of a fourth-order nonlinear evolution equation, under the additional assumption that the density remains bounded away from zero, this lower bound is shown in dimension one and in the radially symmetric case.
Prospects of X-ray imaging spectrometers for impurity transport: Recent results from the stellarator Wendelstein 7-X (invited)
Authors: Langenberg A. , Pablant N. A. , Wegner Th. , Traverso P. , Marchuk O. , Bräuer T. , Geiger B. , Fuchert G. , Bozhenkov S. , Pasch E. , Grulke O. , Kunkel F. , Killer C. , Nicolai D. , Satheeswaran G. , Hollfeld K. P. , Schweer B. , Krings T. , Drews P. , Offermanns G. , Pavone A. , Svensson J. , Alonso J. A. , Burhenn R. , Wolf R. C. ,   W7-X Team
Published: July 2018

This paper reports on the design and the performance of the recently upgraded X-ray imaging spectrometer systems, X-ray imaging crystal spectrometer and high resolution X-ray imaging spectrometer, installed at the optimized stellarator Wendelstein 7-X. High resolution spectra of highly ionized, He-like Si, Ar, Ti, and Fe as well as H-like Ar have been observed. A cross comparison of ion and electron temperature profiles derived from a spectral fit and tomographic inversion of Ar and Fe spectra shows a reasonable match with both the spectrometers. The also measured impurity density profiles of Ar and Fe have peaked densities at radial positions that are in qualitative agreement with the expectations from the He-like impurity fractional abundances, given the measured temperature profiles. Repeated measurements of impurity decay times have been demonstrated with an accuracy of 1 ms via injection of non-recycling Ti, Fe, and Mo impurities using a laser blow-off system.
Lactobacillus plantarum LRCC 5273 isolated from Kimchi ameliorates diet-induced hypercholesterolemia in C57BL/6 mice
Authors: Heo Wan , Lee Eui Seop , Cho Hyung Taek , Kim Jun Ho , Lee Jin Hyup , Yoon Seok Min , Kwon Hoon Tae , Yang Siyoung , Kim Young-Jun
Published: July 2018

This study was designed to select potent cholesterol-lowering probiotic strains on HepG2 cell and investigate the effect of selected strain, Lactobacillus plantarum LRCC 5273 and LRCC 5279 in hypercholesterolemic mice. In the results, LP5273 group showed significantly reduced total and LDL cholesterol compared to HCD group. In addition to significantly up-regulated hepatic mRNA expression of LXR-α and CYP7A1, intestinal LXR-α and ABCG5 were significantly up-regulated in LP5273 group. With activation of hepatic and intestinal LXR-α and its target genes, fecal cholesterol and bile acid excretion were increased in LP5273 fed mice. These results suggest that LP5273 ameliorates hypercholesterolemia in mice through the activation of hepatic and intestinal LXR-α, resulting in enhancement of fecal cholesterol and bile acids excretion in the small intestine. The results of present study suggest mechanistic evidences for hypocholesterolemic effects of L. plantarum spp., and may contribute to future researches for prevention of hypercholesterolemia and cardiovascular disease.
Influence of long-term feeding of high-fat diet on quercetin and fat absorption from the small intestine in lymph duct-cannulated rats
Authors: Makino Ryosuke , Takano Kasumi , Kita Kazumi , Nishimukai Megumi
Published: July 2018

This study aimed to investigate the effect of dietary lipids and a long-term high-fat diet on lymphatic triglyceride and quercetin absorption in rats with a surgically implanted thoracic lymph cannula. Quercetin-3-O-β-glucoside reduced the lymphatic triglyceride output from the intestines; this reduction was prominent among rats fed a high-fat diet.
Organizational ethnography and religious organizations: the case of Quaker decision-making
Authors: Burton Nicholas , Koning Juliette , Muers Rachel
Published: July 2018

How should we study the management practices of religious organizations to do justice to their distinctive religious motivations and traditions? In this article, we articulate how a specific research approach – organizational ethnography – may enable a deeper understanding
of religious and/or spiritual organizational practice. We approach our methodological research questions by engaging with the literature on the distinctive decision-making practices of the Religious Society of Friends (Quakers), commonly known as the Quaker business method. Having shown that
the Quaker business method destabilizes a simple binary between “insider” and “outsider” and between believers and nonbelievers, we bring the theory and practice of organizational ethnography into conversation with Quaker accounts of decision-making. We conclude with
pathways for future research in the space this destabilization creates.
Radiolabelled leucocytes in human pulmonary disease
Authors: Farahi Neda , Loutsios Chrystalla , Tregay Nicola , Summers Charlotte , Lok Laurence S C , Ruparelia Prina , Solanki Chandra K , Gillett Daniel , Chilvers Edwin R , Peters A Michael
Published: July 2018

Introduction

Radionuclides for leucocyte kinetic studies have progressed from non-gamma emitting cell-labelling radionuclides through gamma emitting nuclides that allow imaging of leucocyte kinetics, to the next goal of positron emission tomography (PET).

Sources of data

Mostly the authors’ own studies, following on from studies of the early pioneers.

Areas of controversy

From early imaging studies, it appeared that the majority of the marginated granulocyte pool was located in the lungs. However, later work disputed this by demonstrating the exquisite sensitivity of granulocytes to ex vivo isolation and labelling, and that excessive lung activity is artefactual.

Areas of agreement

Following refinement of labelling techniques, it was shown that the majority of marginated granulocytes are located in the spleen and bone marrow. The majority of leucocytes have a pulmonary vascular transit time only a few seconds longer than erythrocytes. The minority showing slow transit, ~5% in healthy persons, is increased in systemic inflammatory disorders that cause neutrophil priming and loss of deformability. Using a range of imaging techniques, including gamma camera imaging, whole-body counting and single photon-emission computerized tomography, labelled granulocytes were subsequently used to image pulmonary trafficking in lobar pneumonia, bronchiectasis, chronic obstructive pulmonary disease and adult respiratory distress syndrome.

Growing points

More recently, eosinophils have been separated in pure form using magnetic bead technology for the study of eosinophil trafficking in asthma.

Areas timely for developing research

These include advancement of eosinophil imaging, development of monocyte labelling, development of cell labelling with PET tracers and the tracking of lymphocytes.
The Trial of Neville Heath, the Popular Press, and the Construction of the Memory of the Second World War in Britain, 1945–1946
Authors: Grant Matthew
Published: July 2018

This article uses the press coverage of the sensational 1946 trial of Neville Heath for murder as a case-study for exploring how the memory of the Second World War in Britain was constructed in the immediate post-war period. Historians of Europe have described how painful narratives of occupation and defeat were suppressed, and more positive memories of timeless national values highlighted, in order to aid the reconstruction of national identity and gender relations. Although Britain had not experienced such upheaval, the nation did face troubling questions about the consequences of the war for criminality and violence. The popular press, however, discussed such issues in ways which did not call into question the central narratives of the ‘people’s war’. The trial of Heath highlights how questions concerning violence in Britain could be resolved: whereas post-war violent crime was understood in terms of short-term social dislocation rather than the psychological impact of the war, Heath’s sadistic violence was discussed using language which made it readily comparable to the German and Japanese war crimes being featured at the same time. As such, Heath was understandable as an individual, pathologised ‘type’ rather than as a symbol of the post-war British veteran.
Selection Effects with Heterogeneous Firms
Authors: Mrázová Monika , Neary J Peter
Published: July 2018

We characterize how firms select between alternative ways of serving a market. “First-order” selection effects, whether firms enter or not, are extremely robust. “Second-order” ones, how firms serve a market conditional on entry, are much less so: more efficient firms select the entry mode with lower market-access costs if firms’ maximum profits are supermodular in production and market-access costs, but not necessarily otherwise. We derive microfoundations for supermodularity in a range of canonical models. Notable exceptions include horizontal and vertical FDI with “subconvex” demands (i.e., less convex than CES), fixed costs that increase with productivity, and R&D with threshold effects.
An evolutionary perspective on the British banking crisis
Authors: Marshall Neill , Dawley Stuart , Pike Andy , Pollard Jane , Coombes Mike
Published: July 2018

Developing an evolutionary perspective towards the changing anatomy of the banking sector reveals the enduring tensions and contradictions between spatial centralisation and the possibilities for decentralisation before, during and after the British banking crisis. The shift from banking boom to crisis in 2007 is conceptualised as a significant and on-going moment in the long-term evolution of the historical institutional–spatial dominance of London over other city-regions in Britain. The analysis demonstrates the importance of the institutional and geographical legacies of the British national political economy and variegation of capitalism established in the later nineteenth and early twentieth centuries in shaping contemporary geographical outcomes. Regulatory changes combined with financial innovation in the latter years of the twentieth century to create an opportunity for English regional and Scottish banks excluded from previous institutional–spatial centralisation to expand excessively and consequently several failed in the banking crisis. The paper considers the future trajectory of institutional–spatial centralisation in the banking sector amidst the continued spatial restructuring of the banking crisis, involving a re-drawing of organisational boundaries, overlapping institutional and technological changes and unprecedented uncertainty about the impact of Brexit on Britain’s wider political and economic landscape.
Synonymy Between Token-Reflexive Expressions
Authors: Radulescu Alexandru
Published: July 2018

Synonymy, at its most basic, is sameness of meaning. A token-reflexive expression is an expression whose meaning assigns a referent to its tokens by relating each particular token of that particular expression to its referent. The formulation of its meaning accordingly mentions the particular expression whose meaning it is. This seems to entail that no two token-reflexive expressions are synonymous, which would constitute a strong objection against token-reflexive semantics. In this paper, I propose and defend a notion of synonymy for token-reflexive expressions that allows such expressions to be synonymous, while being a fairly conservative extension of the customary notion of synonymy.
A Strategy for PrEP Clinicians to Manage Ambiguous HIV Test Results During Follow-up Visits
Authors: Smith Dawn K , Switzer William M , Peters Philip , Delaney Kevin P , Granade Timothy C , Masciotra Silvina , Shouse Luke , Brooks John T
Published: July 2018

Prompt determination of HIV infection status is critical during follow-up visits for patients taking pre-exposure prophylaxis (PrEP) medication. Those who are uninfected can then continue safely taking PrEP, and those few who have acquired HIV infection can initiate an effective treatment regimen. However, a few recent cases have been reported of ambiguous HIV test results using common testing algorithms in PrEP patients. We review published reports of such cases and testing options that can be used to clarify true HIV status in these situations. In addition, we review the benefits and risks of 3 antiretroviral management options in these patients: (1) continue PrEP while conducting additional HIV tests, (2) initiate antiretroviral therapy for presumptive HIV infection while conducting confirmatory tests, or (3) discontinue PrEP to reassess HIV status after a brief antiretroviral-free interval. A clinical consultation resource is also provided.
A Novel Technique for Prevention of Subarachnoid-Pleural Fistula After Incidental Durotomy During Transthoracic Spinal Surgery
Authors: He Kevin D , Rymarczuk George N , Clark Shannon W , Gillick John L , Vahedi Payman , Sharan Ashwini D
Published: July 2018

BACKGROUND

Subarachnoid-pleural fistulas (SPFs) are rare but significant complications of transthoracic spinal surgery. Whether noted intraoperatively or in the postoperative period, SPF requires implementation of aggressive management, with consideration given to direct surgical repair. Additionally, the physical constraints of the thoracic cavity often hinder direct SPF repair.

OBJECTIVE

To present a novel operative technique that can be used to easily and quickly address incidental durotomy incurred during transthoracic spinal surgery while working within the confines of the thorax.

METHODS

Surgical hemostatic clips were used to affix a patch-graft of dural substitute to the parietal pleura surrounding the site of a transthoracic spinal decompression in which an incidental durotomy was incurred. The patch-graft was augmented with the application of biological glue and was successful in preventing symptomatic SPF.

RESULTS

The use of surgical clips to affix a patch graft is a quick, easy, and effective means of addressing an incidental durotomy during thoracotomy and preventing SPF. The clip applier is significantly easier to maneuver within the narrow working channel of the thorax than are instruments used during direct repair.

CONCLUSION

Preventing SPF can be challenging. The physical constraints of the thoracic cavity make water-tight repair difficult and time-consuming, particularly when the morphology of the dural tear prevents primary apposition of the defect. The authors present a novel technique of preventing development of SPF using hemostatic clips to simply and quickly affix suturable dural substitute to the parietal pleura overlying the site of an incidental durotomy.
Infradentate Approach to the Fourth Ventricle
Authors: Jamshidi Ali O , Priddy Blake , Beer-Furlan Andre , Prevedello Daniel M
Published: July 2018

BACKGROUND

The use of minimally invasive transcranial ports for the resection of deep-seated lesions has been shown to be safe and effective for supratentorial lesions. The routine use of this surgical modality for posterior fossa masses has not been well established in the literature. In particular, fourth ventricular tumors are not the typical target for neuro-port surgery because of potential injury to the dentate nucleus.

OBJECTIVE

To describe the use of a tubular retractor system to reach the fourth ventricle while sparing the cerebellar vermis and the dentate nucleus. Three cases illustrations are presented.

METHODS

Surgical access to the fourth ventricle was developed sparing the cerebellar vermis and the dentate nucleus. The authors reviewed 3 cases to illustrate the feasibility of minimal access transcerebellar port surgery for the resection of these lesions using an infradentate access.

RESULTS

None of the patients developed new neurological deficits and the pathology was successfully resected in all cases. There were no major complications related to surgery and no mortalities.

CONCLUSION

The infradentate approach obviates the need for traditional approaches to the fourth ventricle, thus making this challenging target in the posterior fossa more accessible to neurosurgeons. The authors observed successful removal of lesions involving the fourth ventricle while avoiding any associated morbidity or mortality.
Long sleep duration predicts a higher risk of obesity in adults: a meta-analysis of prospective cohort studies
Authors: Liu Wenjia , Zhang Rui , Tan Anran , Ye Bo , Zhang Xinge , Wang Yueqiao , Zou Yuliang , Ma Lu , Chen Guoxun , Li Rui , Moore Justin B
Published: July 2018

Background

The connections between long sleep duration and obesity or weight gain warrant further examination. This meta-analysis aimed to evaluate whether long sleep duration was associated with the risk of obesity, weight gain, body mass index (BMI) change or weight change in adults.

Methods

PubMed, Embase, Cochrane Library, Elsevier Science Direct, Science Online, MEDLINE and CINAHL were searched for English articles published before May 2017. A total of 16 cohort studies (n = 329 888 participants) from 8 countries were included in the analysis. Pooled relative risks (RR) or regression coefficients (β) with 95% confidence intervals (CI) were estimated. Heterogeneity and publication bias were tested, and sensitivity analysis was also performed.

Results

We found that long sleep duration was associated with higher risk of obesity (RR [95% CI] = 1.04 [1.00–1.09], P = 0.037), but had no significant associations with weight gain, BMI change or weight change. Long sleep duration increased the risk of weight gain in three situations: among men, in studies with <5 years follow-up, and when sleep duration was 9 or more hours.

Conclusions

Long sleep duration was associated with risk of obesity in adults. More cohort studies with objective measures are needed to confirm this relationship.
The Sensitivity and Specificity of Preoperative History, Physical Examination, and Magnetic Resonance Imaging to Predict Articular Cartilage Injuries in Symptomatic Discoid Lateral Meniscus
Authors: Lau Brian C. , Vashon Toure , Janghala Abhinav , Pandya Nirav K.
Published: July 2018

Background:

Discoid lateral meniscus (DLM) is a morphologic variant in which concomitant articular cartilage defects lead to poor outcomes. The purpose of this study was to quantify the prognostic ability of history, physical examination, and magnetic resonance imaging (MRI) to identify arthroscopically confirmed articular cartilage injury in pediatric and adolescent DLM patients.

Methods:

An analysis of 34 consecutive patients (mean, 12.5 y) who underwent surgical treatment for DLM. Patients were grouped based on arthroscopic findings for the presence or absence of articular cartilage injury. All patients underwent standard preoperative history and physical examination, and MRI of their symptomatic knee. Separate discriminant functional analyses were performed using history (age, sex, symptoms lasting >6 mo, traumatic history), physical examination (presence of clunk, extension block, mechanical symptoms), and MRI findings (chondral injury, meniscal degeneration, meniscal morphology) to determine their sensitivity and specificity in prediction of articular cartilage lesions.

Results:

The sensitivity and specificity of history alone was 71.4% and 75.0%, respectively; physical examination alone was 64.3% and 60%, respectively; and of MRI findings alone was 60% and 66.7%, respectively. A stepwise discriminant functional analysis found that duration of symptoms and extension block were the optimal contributors with a 78.5% sensitivity and 80% specificity.

Conclusions:

Preoperative history had the highest sensitivity and specificity compared with physical examination and MRI findings for predicting articular cartilage injury at the time of DLM surgery. These findings may assist in setting expectations for patients with regard to surgical planning and recovery and also to counsel patients with asymptomatic, incidental DLM which factors may risk chondral injury and warrant early return for evaluation.

Level of Evidence:

Level II—retrospective prognostic comparative study.
Predictability of Clinical Knowledge Through Mobile App-based Simulation for the Treatment of Pediatric Septic Arthritis: A Pilot Study
Authors: Shore Benjamin J. , Miller Patricia E. , Noonan Kenneth J. , Bae Donald S.
Published: July 2018

Background:

Recently the American Board of Orthopaedic Surgery and the Accreditation Council of Graduate Medical Education have identified the treatment of septic arthritis of the hip in children as a milestone skill for all US orthopaedic residents. The purpose of this study was to test correlation between clinical knowledge and examination score on a mobile app-based training module for the treatment of pediatric septic hip arthritis.

Methods:

A 4-part simulation model on surgical decision-making associated with the treatment of pediatric septic arthritis was developed through expert consensus. Orthopaedic trainees participating in the “Top Gun” program of the 2015 and 2016 International Pediatric Orthopaedic Symposiums were recruited to participate in this pilot study. Trainees completed a presimulation quiz on their knowledge of diagnosis, arthrocentesis, and surgical irrigation and debridement on a pediatric patient presenting with septic arthritis of the hip. Trainees then completed the 4-part simulation on the mobile app. Pearson correlation analysis was used to assess the relationship between the quiz and the simulation.

Results:

A total of 53 orthopaedic residents and fellows participated in the simulation. Median quiz score was 87 points [interquartile range (IQR), 81 to 94] before the intervention and 100 points (IQR, 94 to 100) postintervention. The median simulation test score was 89 (IQR, 81 to 92) which demonstrated a positive correlation with the postintervention quiz (r=0.44, P<0.001). The preintervention metrics demonstrated a positive correlation with postintervention metrics (r=0.53, P<0.001).

Conclusions:

This study revealed a statistically significant positive correlation between the mobile app simulation and the clinical knowledge of the participants, as well as the ability to improve knowledge about a procedure during the testing period. These findings support the ability for the mobile app to test clinical knowledge. In the current environment of decreased work hours and patient exposure for orthopaedic trainees, mobile app-based simulation has the potential to safely aid in assessment of orthopaedic residents and fellows.
Classifying Adverse Events Following Lower Limb Orthopaedic Surgery in Children With Cerebral Palsy: Reliability of the Modified Clavien-Dindo System
Authors: Zhou Leena , Willoughby Kate , Strobel Natalie , Thomason Pam , Gallagher Charles , Harambasic Mela , Khot Abhay , Graham H. Kerr
Published: July 2018

Background:

The modified Clavien-Dindo (MCD) system is a reliable tool for classifying adverse events (AEs) in hip preservation surgery and has since been utilized in studies involving lower limb surgery for ambulant and nonambulant children with cerebral palsy (CP). However, the profile of AEs recorded in children with CP compared with typically developing children is different, and the reliability of the MCD in CP is unknown. This study aimed to evaluate the interrater and intrarater reliability of the MCD system for classifying AEs following lower limb surgery in children with CP.

Methods:

Eighteen raters were invited to participate, including clinicians from surgical, nursing, and physical therapy professions, and individuals with CP. Following a MCD familiarization session, participants rated 40 clinical scenarios on 2 occasions, 2 weeks apart. Fleiss’ κ statistics were used to calculate interrater and intrarater reliability.

Results:

The overall Fleiss’ κ value for interrater reliability in the first rating was 0.70 (95% confidence interval, 0.61-0.80), and increased to 0.75 (95% confidence interval, 0.66-0.84) in the second rating. The average Fleiss’ κ value for intrarater reliability was 0.78 (range, 0.48 to 1.00). Grading of more severe AEs (MCD III to V) achieved near perfect agreement (κ, 0.87 to 1.00). There was a lower level of agreement for minor AEs (MCD I-II) (κ, 0.53 to 0.55). A κ score of 0 to 0.2 was deemed as poor, 0.21 to 0.4 as fair, 0.41 to 0.6 as good, 0.61 to 0.8 as very good, and 0.81 to 1.0 as almost perfect agreement.

Conclusions:

The MCD System demonstrates a very good interrater and intrarater reliability following lower limb surgery in children with CP. The MCD can be used by clinicians from different health care professions with a high level of reliability. The MCD may improve standardization of AE recording with a view to accurate audits and improved clarity in outcome studies for CP.

Level of Evidence:

Level II—diagnostic.
Gatekeeper Suicide Training's Effectiveness Among Malaysian Hospital Health Professionals: A Control Group Study With a Three-Month Follow-Up
Authors: Siau Ching Sin , Wee Lei-Hum , Ibrahim Norhayati , Visvalingam Uma , Yeap Lena Lay Ling , Wahab Suzaily
Published: July 2018

Introduction:

There is a lack of suicide-related training in the nonpsychiatric health professional's basic education. We suggest that a continuing education through a brief gatekeeper suicide training program could be a suitable platform to improve suicide-related knowledge, self-efficacy, and attitudes. This study aimed at examining the effectiveness of the Question, Persuade, Refer gatekeeper program on improving the knowledge, self-efficacy in suicide prevention, and understanding of/willingness to help suicidal patients of Malaysian hospital health professionals.

Methods:

The Question, Persuade, Refer program materials were translated and adapted for implementation in the hospital setting for nonpsychiatric health professionals. There were 159 (mean age = 35.75 years; SD = 12.26) participants in this study. Most participants were female (84.9%), staff/community nurses (52.2%), who worked in the general medical department (30.2%) and had no experience managing suicidal patients (64.2%). Intervention participants (n = 53) completed a survey questionnaire at pretraining, immediately after training, and after three months. Control participants (n = 106) were not exposed to the training program and completed the same questionnaire at baseline and three months later.

Results:

Significant improvement occurred among intervention participants in terms of perceived knowledge, self-efficacy, and understanding of/willingness to help suicidal patients immediately after training and when compared with the control participants 3 months later. Improvements in declarative knowledge were not maintained at the 3-month follow-up.

Discussion:

This study confirmed the short-term effectiveness of the gatekeeper training program. Gatekeeper suicide training is recommended for implementation for nonpsychiatric health professionals nationwide.
Caffeine as an adulterant of coca paste seized samples: preclinical study on the rat sleep–wake cycle
Authors: Schwarzkopf Natalia , Lagos Patricia , Falconi Atilio , Scorza Cecilia , Torterolo Pablo
Published: July 2018

Caffeine is a common active adulterant found in illicit drugs of abuse, including coca paste (CP). CP is a smokable form of cocaine mainly consumed in South America, produced during the cocaine-extraction process. CP has high abuse liability and its chronic consumption induces severe sleep–wake alterations. However, the effect of CP on the sleep–wake cycle and the effect of the presence of caffeine as an adulterant remain unknown. We studied the effect of an acute intraperitoneal injection of 2.5 and 5 mg/kg of a representative CP sample adulterated with caffeine (CP1) on the rat sleep–wake cycle. Compared with saline, administration of CP1 induced an increase in wakefulness and a decrease in light (light sleep) and slow wave sleep that was larger than the effects produced by equivalent doses of cocaine. Compared with CP1, combined treatment with cocaine (5 mg/kg) and caffeine (2.5 mg/kg), a surrogate of CP1, elicited similar effects. In contrast, a nonadulterated CP sample (CP2) produced an effect that was not different from cocaine. Our data indicate that caffeine produces a significant potentiation of the wakefulness-promoting effect of cocaine, suggesting that caffeine should be explored as a causal agent of clinical symptoms observed in CP users.
EXUDATIVE RETINAL DETACHMENT DOCUMENTED BY HANDHELD SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY AFTER RETINAL LASER PHOTOCOAGULATION FOR RETINOPATHY OF PREMATURITY
Authors: Cabrera Michelle T. , Brewer Erika M. , Grant Laura , Tarczy-Hornoch Kristina
Published: July 2018

Background:

Few cases of exudative retinal detachments have been reported in the literature after laser treatment for retinopathy of prematurity, and none of the cases include optical coherence tomography images.

Methods:

Case report.

Results:

A 469-g birth weight, 25-week gestational age baby girl at 35-week postmenstrual age received a retinal laser (1,724 spots in the right eye and 1,287 spots in the left eye) for bilateral Stage 3 Zone II plus disease retinopathy of prematurity. The patient developed a large macular exudative retinal detachment seen in the right eye at the first follow-up, 5 days after the laser. Serial handheld optical coherence tomography demonstrated resolution of retinal detachment and intraretinal fluid over the course of 4 weeks with only topical tobramycin/dexamethasone ophthalmic ointment 3 to 4 times daily for 2 weeks. The patient was left with a residual subretinal scar and outer retinal loss on optical coherence tomography, with a later appearance of a dragged macula on funduscopic examination noted at 52-week postmenstrual age. It is unclear whether systemic steroid therapy, intravitreal bevacizumab, or surgery would hasten resolution of exudative retinal detachment after the retinopathy of prematurity laser and avoid photoreceptor damage seen on optical coherence tomography in this case.

Conclusion:

This case suggests that post–retinopathy of prematurity laser exudative retinal detachments can resolve without aggressive intervention, but may cause permanent retinal sequelae.
Decreased Serum Levels of Complement C3 Reflect Complement System Dysregulation in Patients With Primary Open-angle Glaucoma: Results From a Pilot Study
Authors: Li Shengjie , Li Danhui , Shao Mingxi , Cao Wenjun , Sun Xinghuai
Published: July 2018

Purpose:

To evaluate the serum complement component (C)3 concentration in patients with primary open-angle glaucoma (POAG) and to investigate the association between C3 levels and POAG severity.

Materials and Methods:

This study enrolled 190 consecutive POAG patients and 204 normal control subjects. A detailed eye and systematic examination, including intraocular pressure, gonioscopy, fundus photography, A-scan ultrasound, visual field testing, electrocardiograms, x-rays, liver function, renal function, infectious disease, etc., and measurement of serum C3 concentration by immunoturbidimetry, was performed. The subgroups were classified according to age (17 to 29, 30 to 49, 50 to 69, 70+ y), sex, and visual field: mild (MD≤6 dB), moderate (6 dB12 dB) glaucoma.

Results:

The serum C3 level of the POAG (95.63±17.71 mg/dL) was ∼20.93% lower than that of the control group (115.65±22.19 mg/dL) (P<0.001). A similar result was observed when serum levels of C3 were compared between the POAG and control groups with respect to age and sex. The mean serum C3 level was lowest in the severe POAG group (85.18±19.62 mg/dL), followed by the moderate POAG group (96.62±12.63 mg/dL) and the mild POAG group (110.44±14.89 mg/dL) (P<0.001). Multiple logistic regression analyses revealed a significant correlation between the C3 levels and the vertical cup-disc ratio (B=−0.373, P=0.026), C3 levels and MD (B=−0.546, P=0.001). Logistic regression analyses revealed that serum C3 levels were associated (odds ratio=0.939, 95% CI=0.901-0.979, P=0.003) with severity of POAG.

Conclusions:

The POAG patients had decreased C3 levels, which were further negatively associated with POAG severity, suggesting the involvement of C3 in the pathomechanisms of POAG.
Characteristics of State Policies Impact Health Care Delivery
Authors: Horný Michal , Shwartz Michael , Duszak Richard , Christiansen Cindy L. , Cohen Alan B. , Burgess James F.
Published: July 2018

Background:

Increased breast tissue density may mask cancer and thus decrease the diagnostic sensitivity of mammography. A patient group advocacy led to the implementation of laws to increase the awareness of breast tissue density and to improve access to supplemental imaging in many states. Given limited evidence about best practices, variation exists in several characteristics of adopted policies.

Objective:

To identify which characteristics of state-level policies with regard to dense breast tissue were associated with increased use of downstream breast ultrasound.

Research Design:

This was a retrospective series of monthly cross-sections of screening mammography procedures before and after implementation of laws.

Subjects:

A sample of 13,481,554 screening mammography procedures extracted from the MarketScan Research database performed between 2007 and 2014 on privately insured women aged 40–64 years that resided in a state that had implemented relevant legislation during that period.

Measures:

The outcome was an indicator of whether breast ultrasound imaging followed a screening mammography procedure within 30 days. The main independent variables were policy characteristics indicators.

Results:

Notification of patients about issues surrounding increased breast density was associated with increased follow-up by ultrasound by 1.02 percentage points (P=0.016). Some policy characteristics such as the explicit suggestion of supplemental imaging or mandated coverage of supplemental imaging by health insurance augmented that effect. Other policy characteristics moderated the effect.

Conclusions:

The heterogeneous effect of state legislation with regard to dense breast tissue on screening mammography follow-up by ultrasound may be explained by specific and unique characteristics of the approaches taken by a variety of states.