bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of management on weeds and aquatic plant communities in Hungarian rice crops
Authors: Pinke G , Csiky J , Mesterházy A , Tari L , Pál RW , Botta‐Dukát Z , Czúcz B
Published: April 2014

This study assessed the cultural and weed management factors influencing the weed communities of Hungarian rice fields. Hungary is situated at the northern limit of rice production with a history of about 300 years of rice culture. We surveyed the weed flora and 25 background variables in 100 active rice fields. Using a minimal adequate model containing 11 terms, 48.5% of the total variation in weed species data could be explained. The net effects of nine variables on species composition were significant. Crop cover was found to be the most important explanatory variable, which was followed by the herbicides penoxsulam and azimsulfuron, tillage depth, phosphorous and potassium fertilisers, years after last rotation, water depth in May, sowing type, pendimethalin and water conductivity. Filamentous algae, as the most abundant group of weeds, were positively associated with deep tillage, deep water and surface sowing. Echinochloa crus‐galli, one of the most troublesome grass weeds, was associated with low rice cover, shallow water and later years after crop rotation, while weedy rice favoured high crop cover, deep water and soil sowing. These findings can be used to design improved weed management strategies. The occurrence of red list species and charophytes in diverse micro‐mosaic patterns deserves attention from a conservation perspective, as well. The maintenance of these unique charophyte communities can be facilitated by shallow tillage without soil inversion.
Stable and Efficient Operation of Gas Compressor With Improving of Surge Detection System
Authors: Mahdi Alavinia Sayyid , Ali Sadrnia Mohammad , Javad Khosrowjerdi Mohammad , Mehdi Fateh Mohammad
Published: April 2014

This paper investigates the application of fault diagnosis (FD) approach for improving performance of compressors within exact operating point determination. Detecting of sensor fault or failure status is more important in the compressor for safety-critical application. No work has previously been reported on the use of the FD system within a compressor surge-suppressing system. Therefore, the main contribution of this paper is presenting different and complementary techniques for surge-suppressing studies via sensor FD. By data acquisition from a nonlinear Moore–Greitzer model, a neural network (NN) and innovation complex decision logic provide residual generation and evaluation blocks in an analytical redundancy FD system, respectively. The proposed FD deals with the most-common sensor faults and failures in seven different scenarios according to their nature, such as bias, cutoff, loss of efficiency, and freeze.
Thermal Resistance Analysis of High Power Light Emitting Diode Using Aluminum Nitride Thin Film-Coated Copper Substrates as Heat Sink
Authors: Shanmugan S. , Mutharasu D.
Published: April 2014

AlN thin film was coated over Cu substrate (575 mm2) with 400 nm thickness using DC sputtering for thermal interface material (TIM) application. Aluminum Nitride (AlN)-coated Cu substrate (AlN/Cu) was used as a heat sink for 3-W green light emitting diode (LED). The thermal transient curve was recorded for given LED attached with bare Cu and AlN-coated Cu substrate at three different driving currents. LED attached on AlN/Cu showed the reduced raise in junction temperature (TJ) by 2.59 °C at 700 mA. The LED/TIM/AlN/Cu boundary condition was not supported to reduce the TJ. The total thermal resistance (Rth-tot) was reduced for AlN-coated Cu substrate at 350 mA. The thermal resistance between metal core printed circuit board and Cu substrate (Rth-b-hs) was also observed as low for AlN-coated Cu substrates compared with other boundary conditions measured at 700 mA. The observed results were supported for the use of AlN thin film as TIM in high power LEDs.
Turbulent Transport at High Reynolds Numbers in an Inertial Confinement Fusion Context
Authors: Melvin J. , Rao P. , Kaufman R. , Lim H. , Yu Y. , Glimm J. , Sharp D. H.
Published: April 2014

Mix is a critical input to hydro simulations used in modeling chemical or nuclear reaction processes in fluids. It has been identified as a possible cause of performance degradation in inertial confinement fusion (ICF) targets. Mix contributes to numerical solution uncertainty through its dependence on turbulent transport coefficients, themselves uncertain and even controversial quantities. These coefficients are a central object of study in this paper, carried out in an Richtmyer–Meshkov unstable circular two-dimensional (2D) geometry suggested by an ICF design. We study a pre-turbulent regime and a fully developed regime. The former, at times between the first shock passage and reshock, is characterized by mixing in the form of interpenetrating but coherent fingers and the latter, at times after reshock, has fully developed turbulent structures. This paper focuses on the scaling of spatial averages of turbulence coefficients under mesh refinement and under variation of molecular viscosity [i.e., Reynolds number (Re)]. We find that the coefficients scale under mesh refinement with a power of spatial grid spacing derived from the Kolmogorov 2/3 law, especially after reshock. We document the dominance of turbulent over molecular transport and convergence of the turbulent transport coefficients in the infinite Re limit. The transport coefficients do not coincide for the pre- and post-reshock flow regimes, with significantly stronger transport coefficients after reshock.
Numerical Vortex-Induced Vibration Prediction of Marine Risers in Time-Domain Based on a Forcing Algorithm
Authors: Ma Peter , Qiu Wei , Spencer Don
Published: April 2014

Vortex-induced vibration (VIV) of marine risers poses a significant challenge as the offshore oil and gas industry moves into deep water. A time-domain analysis tool has been developed to predict the VIV of marine risers based on a forcing algorithm and by making full use of the available high Reynolds number experimental data. In the formulation, the hydrodynamic damping is not treated as a special case but simply an extension of the experimentally derived lift curves. The forcing algorithm was integrated into a mooring analysis program based on the global coordinate-based finite element method. At each time step, the added mass, lifting force, and drag force coefficients and their corresponding loads are computed for each element. Validation studies have been carried out for a full-scale rigid riser segment and a model-scale flexible riser. The numerical results were compared with experimental data and solutions by other programs.
Performance of Proton Exchange Membrane in the Presence of Mg2+
Authors: Li Guo , Tan Jinzhu , Gong Jianming , Zhang Xiaowei , Xin Yanchao , Hu Xuejia
Published: April 2014

Proton exchange membrane (PEM) fuel cell is regarded as one of the potential renewable energy which may provide a possible long-term solution to reduce carbon dioxide emissions, reduce fossil fuel dependency and increase energy efficiency. Even though great progress has been made, long-term stability and durability is still an issue. The contamination ion plays an important role on the electrical performance of PEM fuel cell. This paper investigates the effect of Mg2+ contamination on PEM fuel cell performance as a function of Mg2+ concentration. Two levels of Mg2+ concentration was chose. From the experimental results, it can be obtained that a significant drop in fuel cell performance occurred when Mg2+ was injected into the anode fuel stream. The voltage and power density of fuel cell decreased larger and larger with increase of Mg2+ concentration over time. The Mg2+ mainly caused the concentration polarization loss from the anode catalyst to the membrane in fuel cell.
Parametric Analysis on Hybrid System of Solid Oxide Fuel Cell and Micro Gas Turbine With CO2 Capture
Authors: Zhou Dengji , Mei Jiaojiao , Chen Jinwei , Zhang Huisheng , Weng Shilie
Published: April 2014

The solid oxide fuel cell–micro gas turbine hybrid system with CO2 capture seems to be a prospective system with high efficiency and low emissions. Three hybrid systems with/without CO2 capture are designed and simulated based on the IPSEPro simulation platform. The performance on the design point shows that case 2 is a better one, whose system efficiency is 59% and CO2 capture rate is 99%; thus, case 2 is suitable to build a quasi-zero carbon emission plant. However, case 3 is more suitable to rebuild an existing plant. Then the off-design point performance and the effect of the capture rate on the system performance of cases 2 and 3 are investigated. The suggested capture rate for cases 2 and 3 is given based on the result, taking both economic factors and carbon emissions into consideration.
Fuel Cell Diagnostics Using Identification Measurement Theory
Authors: Koshekov K. T. , Klikushin Yu. N. , Kobenko V. Yu. , Evdokimov Yu. K. , Demyanenko A. V.
Published: April 2014

The possibility to use instruments of identification measurement theory to solve the problems of diagnostics of fuel cells according to their noise characteristics is considered in this paper. The offered techniques of diagnostic signals processing are based on the identification measurement of time and probabilistic characteristics, the comparison of model signals with the ones under analysis according to the reading values, the classification of signals according to the waveform parameter and characteristic frequency, the building of hierarchical structures, and the assessment of the signal structures by the fractal indices. All proposed techniques are applicable for the diagnosis of a fuel cell, but thanks to graphical representation of classification trees of noise signals, the more efficient method for experts is the one based on the building of hierarchical structures.
Heat Transfer Enhancement Characteristics of Al2O3/Water and CuO/Water Nanofluids in a Tube in Tube Condenser Fitted With an Air Conditioning System—An Experimental Comparison
Authors: Chandraprabu V. , Sankaranarayanan G. , Iniyan S. , Suresh S.
Published: April 2014

In this study, heat transfer performance of nanofluids (Al2O3/water and CuO/water nanofluid) is experienced by using the condensing unit of an air conditioner. Nanoparticles at 30 nm are suspended at various volume concentrations (1%, 2%, 3%, and 4%) in the base fluid are produced for this current work. The nanofluids, considered as a cooling fluid, flow in the outer side of the tube of condenser, and general working condition of the air conditioner is applied for the investigation. Experimental results highlight the enhancement of heat transfer rate because of the existence of nanoparticles in the fluid. Two nanofluids show better heat transfer rate than does the base fluid. The Nusselt numbers for CuO/water and Al2O3/water nanofluids are enhanced up to 39.48% and 33.86%, respectively. The findings show that CuO/water nanofluids exhibit better heat transfer rate than Al2O3/water nanofluids.
Experimental Research on a Three-Dimensional Journal Orbit of a Crankshaft Bearing for an Internal Combustion Engine
Authors: Sun Jun , Zhu Xinlong , Zhang Liang , Wang Xianyi , Chai Xiaohui , Yin Wei , Shi Wei
Published: April 2014

The current experimental researches on the orbit of a journal center of a crankshaft bearing for an internal combustion engine were usually focused on the 2D movement locus of a crankshaft journal center in the cross section of the bearing. However, in the actual operation of an internal combustion engine, there exists the movement of a crankshaft journal along the bearing axis under the effect of various factors, such as the crankshaft deformation acted by load. Obviously the tribological performance of a crankshaft bearing is affected inevitably by the movement of the crankshaft journal along the bearing axis. In this paper, a four-stroke four-cylinder internal combustion engine was taken as the studying object, the 3D orbit (that includes the movement in the cross section of the bearing and the movement along the bearing axis) of the journal center of the crankshaft bearing for an internal combustion engine was measured under a number of operating conditions on the test bench of an internal combustion engine. The position of the journal in the crankshaft bearing was obtained by the measurement using eddy current gap sensors and the data post-process. The results show that there exists the movement of the crankshaft journal along the axial direction in the bearing for an internal combustion engine. The actual orbit of the journal center of the crankshaft bearing for an internal combustion engine is a 3D spatial curve. The orbit of the journal center of the crankshaft bearing in one operating cycle of an internal combustion engine is not a closed curve. There is relatively a large movement of the journal along the axial direction of the crankshaft bearing, and the numerical value of the movement is greater than the radial clearance of the bearing. The greater the rotational speed of the internal combustion engine, the larger the amount of axial movement of the journal. The periodic variation exists in the axial movement of the bearing journal in one operating cycle of the internal combustion engine at low engine speed, and the varying periodicity equals the number of engine cylinders. There is no obvious varying rule of the axial movement of the bearing journal in one operating cycle of the internal combustion engine at high engine speed.
Optimization of Journal Bearing Profiles With Respect to Stiffness and Load-Carrying Capacity
Authors: Weißbacher Christoph , Schellnegger Christian , John Alexander , Buchgraber Thomas , Pscheidt Walter
Published: April 2014

This paper presents an optimization algorithm for journal bearing profiles with respect to stiffness and load-carrying capacity and an application example of the same. An analytical approach for finding the optimum is derived. How the optimization procedure works when using numerical calculation tools is briefly explained. The application example is introduced and the expected performance of the optimized bearing profile is compared to the expected performance of state-of-the-art bearing profiles. Finally, the measured bearing performance data is compared to the expected values. The findings indicate the effectiveness of the introduced optimization algorithm.
Multiphysics Investigations on the Dynamics of Differential Hypoid Gears
Authors: Mohammadpour M. , Theodossiades S. , Rahnejat H.
Published: April 2014

Vehicular differential hypoid gears play an important role on the noise, vibration, and harshness (NVH) signature of the drivetrain system. Additionally, the generated friction between their mating teeth flanks under varying load-speed conditions is a source of power loss in a drivetrain while absorbing some of the vibration energy. This paper deals with the coupling between system dynamics and analytical tribology in multiphysics, multiscale analysis. Elastohydrodynamic lubrication (EHL) of elliptical point contact of partially conforming hypoid gear teeth pairs with non-Newtonian thermal shear of a thin lubricant film is considered, including boundary friction as the result of asperity interactions on the contiguous surfaces. Tooth contact analysis (TCA) has been used to obtain the input data required for such an analysis. The dynamic behavior and frictional losses of a differential hypoid gear pair under realistic operating conditions are therefore determined. The detailed analysis shows a strong link between NVH refinement and transmission efficiency, a finding not hitherto reported in literature.
An Experimental and Modeling Study Into Using Normal and Isocetane Fuel Blends as a Surrogate for a Hydroprocessed Renewable Diesel Fuel
Authors: Cowart Jim , Raynes Michael , Hamilton Len , Luning Prak Dianne , Mehl Marco , Pitz William
Published: April 2014

A new hydroprocessed renewable diesel (HRD) fuel comprised both straight chain and branched alkane fuel components. In an effort to find a research surrogate for this fuel, single cylinder engine testing was performed with various blends of n-hexadecane (cetane) and isocetane in order to find a binary surrogate mixture with similar performance characteristics to that of the HRD. A blend of approximately two-thirds n-hexadecane with one-third isocetane showed the most similar behavior based on conventional combustion metrics. Companion combustion modeling was then pursued using a combined detailed chemical kinetic mechanism for both n-hexadecane and isocetane. These modeling results show both the importance of isocetane in lengthening ignition delay (IGD), as well as the overall importance of chemical ignition delay as the dominating effect in the overall ignition delay of these binary blend fuels.
Power Absorption Modeling and Optimization of a Point Absorbing Wave Energy Converter Using Numerical Method
Authors: Pastor Jeremiah , Liu Yucheng
Published: April 2014

This paper presents, assesses, and optimizes a point absorber wave energy converter (WEC) through numerical modeling, simulation, and analysis. Wave energy conversion is a technology uniquely suited for assisting in power generation in the offshore oil and gas platforms. A linear frequency domain model is created to predict the behavior of the heaving point absorber WEC system. The hydrodynamic parameters are obtained with AQWA, a software package based on boundary element methods. A linear external damping coefficient is applied to enable power absorption and an external spring force is introduced to tune the point absorber to the incoming wave conditions. The external damping coefficient and external spring forces are the control parameters, which need to be optimized to maximize the power absorption. Two buoy shapes are tested and a variety of diameters and drafts are compared. Optimal shape, draft, and diameter of the model are then determined to maximize its power absorption capacity.
Optimization of Strut Placement in Flow Diverter Stents for Four Different Aneurysm Configurations
Authors: Anzai Hitomi , Falcone Jean-Luc , Chopard Bastien , Hayase Toshiyuki , Ohta Makoto
Published: April 2014

A modern technique for the treatment of cerebral aneurysms involves insertion of a flow diverter stent. Flow stagnation, produced by the fine mesh structure of the diverter, is thought to promote blood clotting in an aneurysm. However, apart from its effect on flow reduction, the insertion of the metal device poses the risk of occlusion of a parent artery. One strategy for avoiding the risk of arterial occlusion is the use of a device with a higher porosity. To aid the development of optimal stents in the view point of flow reduction maintaining a high porosity, we used lattice Boltzmann flow simulations and simulated annealing optimization to investigate the optimal placement of stent struts. We constructed four idealized aneurysm geometries that resulted in four different inflow characteristics and employed a stent model with 36 unconnected struts corresponding to the porosity of 80%. Assuming intracranial flow, steady flow simulation with Reynolds number of 200 was applied for each aneurysm. Optimization of strut position was performed to minimize the average velocity in an aneurysm while maintaining the porosity. As the results of optimization, we obtained nonuniformed structure as optimized stent for each aneurysm geometry. And all optimized stents were characterized by denser struts in the inflow area. The variety of inflow patterns that resulted from differing aneurysm geometries led to unique strut placements for each aneurysm type.
Sustained Normalization of Neurological Disease after Intracranial Gene Therapy in a Feline Model
Authors: McCurdy Victoria J. , Johnson Aime K. , Gray-Edwards Heather L. , Randle Ashley N. , Brunson Brandon L. , Morrison Nancy E. , Salibi Nouha , Johnson Jacob A. , Hwang Misako , Beyers Ronald J. , Leroy Stanley G. , Maitland Stacy , Denney Thomas S. , Cox Nancy R. , Baker Henry J. , Sena-Esteves Miguel , Martin Douglas R.
Published: April 2014

In a feline model of lysosomal storage disease, intracranial gene therapy achieved therapeutic efficacy in the CNS and increased long-term survival.
Reversal of Persistent Fibrosis in Aging by Targeting Nox4-Nrf2 Redox Imbalance
Authors: Hecker Louise , Logsdon Naomi J. , Kurundkar Deepali , Kurundkar Ashish , Bernard Karen , Hock Thomas , Meldrum Eric , Sanders Yan Y. , Thannickal Victor J.
Published: April 2014

Fibrosis resolution is impaired by aging and is mediated by altered cellular redox homeostasis because of a Nox4-Nrf2 imbalance that promotes an apoptosis-resistant myofibroblast phenotype.
Noninvasive Prenatal Testing Goes Global
Authors: Chandrasekharan, Subhashini , Minear Mollie A. , Hung Anthony , Allyse Megan
Published: April 2014

Noninvasive prenatal genetic testing is becoming available worldwide, but many practical and ethical challenges in the developing world should be considered.
The
GRM
Face of Chondromyxoid Fibroma
Authors: Faltas Bishoy M.
Published: April 2014

Whole-genome sequencing of chondromyxoid fibromas identified up-regulation of a glutamate receptor–encoding gene as a specific driver of tumorigenesis.
Noncanonical MicroRNA (miRNA) Biogenesis Gives Rise to Retroviral Mimics of Lymphoproliferative and Immunosuppressive Host miRNAs
Authors: Kincaid Rodney P. , Chen Yating , Cox Jennifer E. , Rethwilm Axel , Sullivan Christopher S.
Published: April 2014

MicroRNAs (miRNAs) play regulatory roles in diverse processes in both eukaryotic hosts and their viruses, yet fundamental questions remain about which viruses code for miRNAs and the functions that they serve. Simian foamy viruses (SFVs) of Old World monkeys and apes can zoonotically infect humans and, by ill-defined mechanisms, take up lifelong infections in their hosts. Here, we report that SFVs encode multiple miRNAs via a noncanonical mode of biogenesis. The primary SFV miRNA transcripts (pri-miRNAs) are transcribed by RNA polymerase III (RNAP III) and take multiple forms, including some that are cleaved by Drosha. However, these miRNAs are generated in a context-dependent fashion, as longer RNAP II transcripts spanning this region are resistant to Drosha cleavage. This suggests that the virus may avoid any fitness penalty that could be associated with viral genome/transcript cleavage. Two SFV miRNAs share sequence similarity and functionality with notable host miRNAs, the lymphoproliferative miRNA miR-155 and the innate immunity suppressor miR-132. These results have important implications regarding foamy virus biology, viral miRNAs, and the development of retroviral-based vectors.

IMPORTANCE
Fundamental questions remain about which viruses encode miRNAs and their associated functions. Currently, few natural viruses with RNA genomes have been reported to encode miRNAs. Simian foamy viruses are retroviruses that are prevalent in nonhuman host populations, and some can zoonotically infect humans who hunt primates or work as animal caretakers. We identify a cluster of miRNAs encoded by SFV. Characterization of these miRNAs reveals evolutionarily conserved, unconventional mechanisms to generate small RNAs. Several SFV miRNAs share sequence similarity and functionality with host miRNAs, including the oncogenic miRNA miR-155 and innate immunity suppressor miR-132. Strikingly, unrelated herpesviruses also tap into one or both of these same regulatory pathways, implying relevance to a broad range of viruses. These findings provide new insights with respect to foamy virus biology and vectorology.
Antibody-Mediated Inhibition of Ricin Toxin Retrograde Transport
Authors: Yermakova Anastasiya , Klokk Tove Irene , Cole Richard , Sandvig Kirsten , Mantis Nicholas J.
Published: April 2014

Ricin is a member of the ubiquitous family of plant and bacterial AB toxins that gain entry into the cytosol of host cells through receptor-mediated endocytosis and retrograde traffic through thetrans-Golgi network (TGN) and endoplasmic reticulum (ER). While a few ricin toxin-specific neutralizing monoclonal antibodies (MAbs) have been identified, the mechanisms by which these antibodies prevent toxin-induced cell death are largely unknown. Using immunofluorescence confocal microscopy and a TGN-specific sulfation assay, we demonstrate that 24B11, a MAb against ricin’s binding subunit (RTB), associates with ricin in solution or when prebound to cell surfaces and then markedly enhances toxin uptake into host cells. Following endocytosis, however, toxin-antibody complexes failed to reach the TGN; instead, they were shunted to Rab7-positive late endosomes and LAMP-1-positive lysosomes. Monovalent 24B11 Fab fragments also interfered with toxin retrograde transport, indicating that neither cross-linking of membrane glycoproteins/glycolipids nor the recently identified intracellular Fc receptor is required to derail ricin en route to the TGN. Identification of the mechanism(s) by which antibodies like 24B11 neutralize ricin will advance our fundamental understanding of protein trafficking in mammalian cells and may lead to the discovery of new classes of toxin inhibitors and therapeutics for biodefense and emerging infectious diseases.

IMPORTANCERicin is the prototypic member of the AB family of medically important plant and bacterial toxins that includes cholera and Shiga toxins. Ricin is also a category B biothreat agent. Despite ongoing efforts to develop vaccines and antibody-based therapeutics against ricin, very little is known about the mechanisms by which antibodies neutralize this toxin. In general, it is thought that antibodies simply prevent toxins from attaching to cell surface receptors or promote their clearance through Fc receptor (FcR)-mediated uptake. In this report, however, we describe a neutralizing monoclonal antibody (MAb) against ricin’s binding subunit (RTB) that not only associates with ricin after the toxin has bound to the cell’s surface but actually enhances toxin uptake into host cells. Following endocytosis, the antibody-toxin complexes are then routed for degradation. The results of this study are important because they reveal a previously unappreciated role for B-subunit-specific antibodies in intracellular neutralization of ricin toxin.
Novel Determinants of Antibiotic Resistance: Identification of Mutated Loci in Highly Methicillin-Resistant Subpopulations of Methicillin-Resistant Staphylococcus aureus
Authors: Dordel Janina , Kim Choonkeun , Chung Marilyn , Pardos de la Gándara María , Holden Matthew T. J. , Parkhill Julian , de Lencastre Hermínia , Bentley Stephen D. , Tomasz Alexander
Published: April 2014

We identified mutated genes in highly resistant subpopulations of methicillin-resistant
Staphylococcus aureus
(MRSA) that are most likely responsible for the historic failure of the β-lactam family of antibiotics as therapeutic agents against these important pathogens. Such subpopulations are produced during growth of most clinical MRSA strains, including the four historically early MRSA isolates studied here. Chromosomal DNA was prepared from the highly resistant cells along with DNA from the majority of cells (poorly resistant cells) followed by full genome sequencing. In the highly resistant cells, mutations were identified in 3 intergenic sequences and 27 genes representing a wide range of functional categories. A common feature of these mutations appears to be their capacity to induce high-level β-lactam resistance and increased amounts of the resistance protein PBP2A in the bacteria. The observations fit a recently described model in which the ultimate controlling factor of the phenotypic expression of β-lactam resistance in MRSA is a RelA-mediated stringent response.

IMPORTANCE
It has been well established that the level of antibiotic resistance (i.e., minimum concentration of a β-lactam antibiotic needed to inhibit growth) of a methicillin-resistant
Staphylococcus aureus
(MRSA) strain depends on the transcription and translation of the resistance protein PBP2A. Here we describe mutated loci in an additional novel set of genetic determinants that appear to be essential for the unusually high resistance levels typical of subpopulations of staphylococci that are produced with unique low frequency in most MRSA clinical isolates. We propose that mutations in these determinants can trigger induction of the stringent stress response which was recently shown to cause increased transcription/translation of the resistance protein PBP2A in parallel with the increased level of resistance.
Forceps-induced birth injury to the cornea
Authors: Alobaidy Ruba , Srinivasan Sathish
Published: April 2014

A 72-year-old man was referred for cataract surgery in the right eye. On slit-lamp biomicroscopy he was noted to have a vertical split in the Descemet's membrane in the left cornea. Based on the appearance, orientation of the split and medical history of forceps delivery, a forceps injury to the left cornea was diagnosed. The break in Descemet's membrane is characteristically vertical due to the horizontal stretching of the globe which occurs with vertical compression of the globe between the orbit and the blade of the obstetric forceps. Forceps injuries are usually unilateral and affect the left eye as the most common fetal head position is left occiput anterior. In the immediate postpartum period the rupture in the Descemet's membrane leads to corneal oedema which eventually disappears leaving the visible edges of the break. This injury also leads to severe left eye astigmatism and secondary amblyopia.
Myopericytoma of the parotid region treated by extracapsular dissection
Authors: Bates Anthony Simon , Craig Paul , Knepil Greg J
Published: April 2014

Myopericytoma (MPC) is a vascular neoplasm exhibiting differentiation towards perivascular cells. Variable cytoarchitechtural features are visible within MPC, and there is much overlap between MPC, myofibroma and glomus tumours. MPC have a local recurrence rate of 10–20% and malignancy has been described in a few published cases. Previously, superficial parotidectomy has been recommended for MPC but, in this case, the surgical approach was via extracapsular dissection (ECD). A 66-year-old Caucasian man presented with a palpable mass arising from the superficial lobe of the right parotid gland. Following removal by ECD, the histopathological diagnosis of MPC was made. This is the first published report describing ECD of MPC associated with the parotid gland. ECD is preferable to superficial parotidectomy for small superficial lesions such as MPC, with similar oncological outcomes and fewer functional and aesthetic complications.
Immune-inflammatory markers in massively disseminated cysticercosis
Authors: Panda Akhila Kumar , Pati Binod Kumar
Published: April 2014

Disseminated cysticercosis is a common endemic tropical infection. We report a 24-year-old man who presented with a single episode of focal seizure and transient depression. Imaging studies revealed disseminated vesicular cysticercosis involving almost all the body parts. In spite of severe dissemination and significantly raised immunological inflammatory markers, the patient had negligible symptoms. He was subsequently followed up with oral corticosteroid and antiepileptic drug without further complication. The extensive dissemination, relatively benign nature of the disease and clinicoradiological discordance are interesting to describe. This neglected tropical infection can sometimes be alarming and needs public health awareness.
A young woman with abdominal distension
Authors: Appleby Richard , Saroya Haseeb , Postgate Aymer , Meer Ziad
Published: April 2014

We present the case of a 34-year-old woman with haemorrhagic ascites and an extrinsic rectal mass on endoscopy. Endometrioma was subsequently confirmed by laparoscopy and biopsy. Intestinal endometriosis is common, and often mimics other gastrointestinal pathology. Haemorrhagic ascites or intestinal masses are rare presentations of endometriosis, and this is the only reported case of both occurring together. Endometriosis and ascites are more common in women of African descent, and although histological diagnosis requires laparoscopy, MRI has a high negative predictive value; 95% for intestinal endometriosis. Re-accumulation of ascites were prevented by starting a gonadotrophin antagonist.
Hypercalcaemia and acute kidney injury following administration of vitamin D in granulomatous disease
Authors: Tollitt James , Solomon Laurie
Published: April 2014

Vitamin D deficiency is common. It causes osteomalacia, may contribute to osteoporosis and is an independent risk factor for cancer, diabetes, multiple sclerosis, cardiovascular disease and all-cause mortality. We describe patients with a history of sarcoidosis who developed acute kidney injury due to hypercalcaemia following treatment with colecalciferol.
Thyrotoxic hypokalaemic periodic paralysis: a rare presentation of Graves’ disease in a Hispanic patient
Authors: Matta Abhishek , Koppala Jahnavi , Gossman William
Published: April 2014

A 26-year-old Hispanic man with no significant medical history presented to our emergency room with gradual onset weakness of his lower extremities. He was haemodynamically stable and examination revealed loss of motor function in his lower limbs up to the level of hips. Laboratory data revealed hypokalaemia. The patient was started on potassium supplementation and he recovered his muscle strength. Differential diagnosis included familial hypokalaemic periodic paralysis and thyrotoxic periodic paralysis (TPP). Further investigations revealed a low thyroid-stimulating hormone and high free thyroxine levels. Radio iodine 123 scan revealed an enhanced homogeneous uptake in the thyroid suggesting Graves’ disease. Thyroid stimulating antibodies were also found to be elevated. The patient was started on methimazole and propranolol and he never had another attack of TPP even at 1 year follow-up.
An ingested foreign body: two sides of the same coin?
Authors: Varadharajan Kiran , Magill Jennifer , Patel Kalpesh
Published: April 2014

A 2-year-old child presented to the emergency department with an acute onset of dysphagia and stertor. A plain anteroposterior chest X-ray revealed a single circular opacity in the middle third of the oesophagus consistent with an ingested coin. The child was taken to the theatre for rigid pharyngo-oesophagoscopy and removal of the coin. After the first coin was removed subsequent endoscopic examination revealed a second coin at the same location. This extremely rare case of two ingested coins becoming impacted with perfect radiological alignment emphasises the importance of thorough examination on endoscopy and the potential limitations of an X-ray in initial assessment of an ingested foreign body.
Non-steroidal anti-inflammatory drugs and the risk of atrial fibrillation: a population-based follow-up study
Authors: Krijthe Bouwe P , Heeringa Jan , Hofman Albert , Franco Oscar H , Stricker Bruno H
Published: April 2014

Objective

To investigate the association of non-steroidal anti-inflammatory drugs (NSAIDs) and the risk of atrial fibrillation in a prospective community-based follow-up study of elderly individuals with uniform case assessment and data on potential confounders.

Design

Data came from the population-based follow-up study, the Rotterdam Study.

Participants

The study comprised 8423 participants without atrial fibrillation at baseline.

Main outcome measures

Atrial fibrillation was ascertained from ECG assessments as well as medical records. Use of NSAIDs was obtained from automated prescription records by linkage with participating pharmacies. We used Cox proportional hazards models to study the association between NSAID drug use and atrial fibrillation. Use of NSAIDs was included in the model as a time-varying variable.

Results

At baseline, the mean age of the study population was 68.5 years (SD: 8.7) and 58% were women. During a mean follow-up of 12.9 years, 857 participants developed atrial fibrillation. Current use of NSAIDs was associated with increased risk compared with never-use (HR 1.76, 95% CI 1.07 to 2.88). Also, recent use (within 30 days after discontinuation of NSAIDs) was associated with an increased risk of atrial fibrillation compared with never-use (HR 1.84, 95% CI 1.34 to 2.51) adjusted for age, sex and several potential confounders.

Conclusions

In this study, use of NSAIDs was associated with an increased risk of atrial fibrillation. Further studies are needed to investigate the underlying mechanisms behind this association.
Psychiatric disorders among men voluntarily in treatment for violent behaviour: a cross-sectional study
Authors: Askeland Ingunn Rangul , Heir Trond
Published: April 2014

Objectives

Although violent behaviour and psychopathology often co-occur, there has been little research on psychiatric disorders among men in treatment for intimate partner violence (IPV). This study aimed to examine the prevalence of a broad spectrum of psychiatric disorders among men voluntarily attending treatment for IPV.

Setting

5 clinics for IPV treatment, located in the east, south and west of Norway, participated in the study. In a cross-sectional design, men attending therapy for violence against a partner went through a face-to-face structured diagnostic interview, the Mini International Neuropsychiatric Interview.

Participants

222 men contacted the clinic during the inclusion period; 12 men did not attend and 13 men were referred to outpatient clinics. Of the 197 men who were offered therapy, 13 did not provide consent to participate in the study, 2 were excluded and 3 men missed the interview.

Results

A total of 179 men participated in the study. The majority were ethnic Norwegians (88%). A total of 70.9% of the men fulfilled the diagnostic criteria for at least one ongoing psychiatric disorder. Three categories of disorders stood out with approximately equal prevalences: depressive disorders (40.6%), anxiety disorders (38.5%) including post-traumatic stress disorder (18.4%) and alcohol/substance abuse (40.2%). Antisocial personality disorder was present in approximately 2/10 participants. Comorbidity was high, with nearly half of the men (48.0%) assigned two or more diagnoses.

Conclusions

Men voluntarily admitted to treatment for IPV harbour a wide spectrum of psychiatric disorders. Our findings suggest a need for screening procedures for psychiatric disorders as well as adoption of treatment interventions according to different types of psychopathologies and therapeutic needs. Limitations include caution in terms of generalisation to other populations not voluntarily admitted to treatment for IPV, and risk of ignoring symptoms not covered by a clinical structured interview.
Exposure to combined oral contraceptives and risk of venous thromboembolism: a protocol for nested case–control studies using the QResearch and the CPRD databases
Authors: Vinogradova Yana , Coupland Carol , Hippisley-Cox Julia
Published: April 2014

Introduction

Many studies have found an increased risk of venous thromboembolism (VTE) associated with the use of combined hormonal contraceptives, but various methodologies have been used in the study design relating to definition of VTE event and the selection of appropriate cases for analysis. This study will focus on common oral hormonal contraceptives, including compositions with cyproterone because of their contraceptive effect and will perform a number of sensitivity analyses to compare findings with previous studies.

Methods and analysis

2 nested case–control studies will be based on the general population using records from UK general practices within the QResearch and Clinical Practice Research Datalink databases. Cases will be female patients aged 15–49 with primary VTE diagnosed between 2001 and 2013. Each case will be matched by age, year of birth and practice to five female controls, who are alive and registered with the practice at the time of diagnosis of the case (index date). Exposure to different hormonal contraceptives will be defined as at least one prescription for that contraceptive in the year before the index date. The effects of duration and the length of any gap since last use will also be investigated. Conditional logistic regression will be applied to calculate ORs adjusted for smoking, ethnicity, comorbidities and use of other medications. Possible indications for prescribing hormonal contraceptives, such as menstrual disorders, acne or hirsutism will be included in the analyses as confounding factors. A number of sensitivity analyses will be carried out.

Ethics and dissemination

The initial protocol has been reviewed and approved by ISAC (Independent Scientific Advisory Committee) for Medicine and Healthcare Products Regulatory Agency Database Research. The project has also been reviewed by QResearch and meets the requirements of the Trent Research Ethics Committee. The results will be published in a peer-reviewed journal.
Diagnostic quality and accuracy of low dose 3D-DSA protocols in the evaluation of intracranial aneurysms
Authors: Pearl Monica S , Torok Collin , Katz Zinovy , Messina Steven A , Blasco Jordi , Tamargo Rafael J , Huang Judy , Leigh Richard , Zeiler Steven , Radvany Martin , Ehtiati Tina , Gailloud Philippe
Published: April 2014

Background

3D-DSA is the ‘gold standard’ imaging technique for the diagnosis and characterization of intracranial aneurysms.

Objective

To compare the image quality and accuracy of low dose 3D-DSA protocols in patients with unruptured intracranial aneurysms.

Materials and methods

The standard manufacturer 5 s 0.36 μGy/f protocol and one of three low dose 3D-DSA protocols (5 s 0.10 μGy/f, 5 s 0.17 μGy/f, 5 s 0.24 μGy/f) were performed in 12 patients with unruptured intracranial aneurysms. Three interventional neuroradiologists, two neurosurgeons, and two neurologists rated the image quality of all 3D reconstructions as good, acceptable, or poor. Three interventional neuroradiologists measured two dimensions of each aneurysm for all protocols. The radiation dose metric Ka,r (reference point air kerma, in mGy) was recorded for each 3D-DSA protocol.

Results

The standard 5 s 0.36 μGy/f protocol earned the highest average subjective rating of 2.76, followed by the 5 s 0.24 μGy/f (2.72), and 5 s 0.17 μGy/f (2.59) protocols. The ranges of differences in aneurysm measurements between the 5 s 0.24 μGy/f protocol and the standard were <0.5 mm. The median Ka,r metrics for each protocol were as follows: 5 s 0.36 μGy/f (89.0 mGy), 5 s 0.24 μGy/f (57.7 mGy), 5 s 0.17 μGy/f (45.9 mGy), and 5 s 0.10 μGy/f (27.6 mGy).

Conclusions

Low dose 3D-DSA protocols with preserved image quality are achievable, and can help reduce exposure of patients and operators to unnecessary radiation. The 5 s 0.24 μGy/f protocol generates one-third smaller radiation dose than the standard 5 s 0.36 μGy/f protocol without compromising diagnostic image quality or accuracy.
N-butyl cyanoacrylate embolization using a detachable tip microcatheter: initial experience
Authors: Paramasivam Srinivasan , Altschul David , Ortega-Gutiarrez Santiago , Fifi Johanna , Berenstein Alejandro
Published: April 2014

Introduction

Endovascular embolization of intracranial vascular malformations with N-butyl cyanoacrylate (nBCA) using a detachable tip microcatheter allows prolonged injection and decreases the risk of catheter retention.

Methods

Between March and December 2013, the Apollo 1.5 cm detachable tip microcatheter was used in five patients after being approved by both the Food and Drug Administration and the institutional review board as a compassionate use device. Nine pedicles were embolized and the follow-up ranged from 1 to 3 months.

Results

Five of the nine catheter tips detached. The length of reflux was not directly associated with the detachment of the distal tip. There were no cases of premature microcatheter detachment during navigation, manipulation with multiple microguidewire reintroduction and guidance. There was no leak of embolic agent at the detachment zone. Follow-up showed the detached tip to be stable without migration.

Conclusions

A detachable tip microcatheter offers an advance in the safety and effectiveness of nBCA embolization. Catheter retrieval becomes more controlled and less traumatic. Our initial experience is encouraging, and more experience is needed to categorically ascertain its safety and efficacy.
Outstanding issues in excavation of deep and long rock tunnels: a case study
Authors: Zhang Guo-Hua , Jiao Yu-Yong , Wang Hao
Published: April 2014

Excavation of deep and long tunnels faces several distinctive challenges such as unknown geological structures, high groundwater pressure, and high in situ stress, as compared with conventional tunnels. The deep and long Taining tunnel in Fujian Province, South China, was excavated in complex geological settings. This tunnel had to pass through various squeezing fault zones and intensely jointed zones. Large deformations and high-pressure groundwater were frequently encountered during excavation. To predict the potential adverse geological structures, a comprehensive method, which included tunnel seismic prediction and ground penetration radar detection as well as horizontal drilling, was developed. Energy release and pressure reduction, as well as timely sealing, pre-excavation curtain grouting, and radial grouting were adopted to control the high-pressure groundwater. Countermeasures including improvement of support stiffness, double-layered primary support, and pre-support, increase of preset deformation, grouting reinforcement, and timely installation of permanent lining were taken to ensure safe construction in the surrounding rock masses under high in situ stress.
Comparison of reactivity of C,N-chelated and Lappert’s stannylenes with trimethylsilylazide
Authors: Švec Petr , Padělková Zdeňka , Alonso Mercedes , De Proft Frank , Růžička Aleš
Published: April 2014

Two mixed amido-azido tin(IV) species bearing either C,N-chelating or bulky amido ligands were prepared by the reaction of the corresponding stannylene (e.g., Sn[N(SiMe3)2]2 (1) or (LCN)2Sn (2, LCN = 2-(N,N-dimethylaminomethyl)phenyl)) with Me3SiN3. Both products of the oxidative addition, Sn[N(SiMe3)2]3N3 (3) and (LCN)2Sn[N(SiMe3)2]N3 (5), respectively, were fully characterized by both multinuclear NMR spectroscopy and XRD analysis. Heating of a mixture of 2 and Me3SiN3 up to 100 °C lead to the formation of a novel dimeric species (LCN)2Sn(μ-NSiMe3)2Sn(LCN)2 (4), where the two tin atoms are bridged by two NSiMe3 ligands, thus forming a four-membered diazadistannacycle. DFT calculations were also carried out to support the proposed reaction mechanisms.
A note on Reidemeister torsion and pleated surfaces
Authors: Sozen Yasar
Published: April 2014

This paper uses the notion of ℂ-symplectic chain complex and proves an explicit formula for the Reidemeister torsion of an arbitrary ℂ-symplectic chain complex in terms of intersection forms of the homologies. In applications, the formula is applied to closed manifolds and also compact manifolds with boundary by using the homologies with coefficients in complex numbers field. Moreover, an explicit formula for the Reidemeister torsion of representations from the fundamental group of a closed oriented hyperbolic surface to PSL2(ℂ) is presented in terms of the cup product of twisted cohomologies, which is related with Weil–Petersson form and thus the Thurston symplectic form. The formula is also applied to pleated surfaces.