bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic compatibility of actives encapsulated into PEG‐PLA nanoparticles: In Silico predictions and experimental verification
Authors: Erlebach Andreas , Ott Timm , Otzen Christoph , Schubert Stephanie , Czaplewska Justyna , Schubert Ulrich S. , Sierka Marek
Published: July 2016

Achieving optimal solubility of active substances in polymeric carriers is of fundamental importance for a number of industrial applications, including targeted drug delivery within the growing field of nanomedicine. However, its experimental optimization using a trial‐and‐error approach is cumbersome and time‐consuming. Here, an approach based on molecular dynamics (MD) simulations and the Flory–Huggins theory is proposed for rapid prediction of thermodynamic compatibility between active species and copolymers comprising hydrophilic and hydrophobic segments. In contrast to similar methods, our approach offers high computational efficiency by employing MD simulations that avoid explicit consideration of the actual copolymer chains. The accuracy of the method is demonstrated for compatibility predictions between pyrene and nile red as model dyes as well as indomethacin as model drug and copolymers containing blocks of poly(ethylene glycol) and poly(lactic acid) in different ratios. The results of the simulations are directly verified by comparison with the observed encapsulation efficiency of nanoparticles prepared by nanoprecipitation. © 2016 Wiley Periodicals, Inc.
Generation of a LacZ reporter transgenic mouse line for the stereological analysis of oligodendrocyte loss in galactosylceramidase deficiency
Authors: Zhu Hongling , Ornaghi Francesca , Belin Sophie , Givogri Maria I. , Wrabetz Lawrence , Bongarzone Ernesto R.
Published: July 2016

Krabbe's disease is a leukodystrophy resulting from deficiency of galactosylceramidase and the accumulation of galactosylsphingosine (psychosine) in the nervous system. Psychosine is believed to cause central demyelination by killing oligodendrocytes. Quantitative analysis of this process is lacking. To address this, we generated a new transgenic reporter twitcher line in which myelinating oligodendrocytes are genetically marked by the expression of LacZ under control of the myelin basic protein (MBP) promoter. MBP‐LacZ‐twitcher transgenic mice were used for unbiased stereological quantification of β‐galactosidase+ oligodendrocytes in the spinal cord. As expected, we found decreased numbers of these cells in mutant cords, paralleling the severity of clinical disease. The decrease of oligodendrocytes does not correlate well with the increase of psychosine. The new MBP‐LacZ‐twitcher line will be a useful genetic tool for measuring changes in oligodendrocyte numbers in different regions of the mutant CNS and in preclinical trials of therapies to prevent demyelination. © 2016 Wiley Periodicals, Inc.
Optimal TiO2–Graphene Oxide Nanocomposite for Photocatalytic Activity under Sunlight Condition: Synthesis, Characterization, and Kinetics
Authors: Rezaei Mostafa , Salem Shiva
Published: July 2016

TiO2–graphene oxide nanocomposites have been fabricated by the sol–gel technique for degradation of a typical cationic dye solution. The prepared photocatalysts were characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric‐differential analyses, Brunauer–Emmett–Teller surface area measurement, and scanning and transmission electron microscopy. In addition, the photocatalytic activities of samples were evaluated by degradation of methylene blue aqueous solution under the sunlight irradiation. The change in color of solution was evaluated by the UV–vis spectroscopy, and the maximum photocatalytic decoloration (94%) was achieved within 60 min, which exceeded that of pure anatase under the same conditions. The results show that the nanocomposite containing 9.0 wt% of graphene oxide has the superior photocatalytic performance to either single‐phase anatase or other composites containing different amounts of graphene oxide. The experimental degradation data obtained from the batch tests were analyzed by a modified kinetic model, which predicted the performance with higher regression coefficients and lower relative errors. The distribution of TiO2 nanoparticles (<20 nm) on graphene oxide sheets is proposed to be the efficient factor in the homogeneous degradation of dye which can concomitantly improve the photocatalytic activity.
Bond strength of epoxy resin‐based root canal sealer to human root dentin irradiated with Er,Cr:YSGG laser
Authors: Franceschini Keila de Almeida , Silva‐Sousa Yara Teresinha Corrêa , Lopes Fabiane Carneiro , Pereira Rodrigo Dantas , Palma‐Dibb Regina Guenka , de Sousa‐Neto Manoel Damião
Published: July 2016

Objective

The aim was to evaluate the influence of Er,Cr:YSGG laser irradiation associated with different final irrigation protocols on the bond strength of epoxy resin‐based root canal sealer to root dentin, on the dentin/filling material interface and in the temperature variation during irradiation.

Methodology

Ninety‐six maxillary canines were prepared with K3 rotary system up to #45/0.02 instrument, irrigating with distilled water between files. The specimens were randomly assigned to three groups—final irrigation (distilled water, 1% NaOCl, and 17% EDTAC) and four subgroups (n = 8)—laser parameters (non‐irradiated, 2 W/20 Hz, 3 W/20 Hz, and 4 W/20 Hz). During irradiation, the temperatures were measured on the outer root dentin wall in the three thirds, and root apex. Canals were filled with lateral condensation of AHPlus sealer and gutta‐percha cones. Two slices from each third were submitted to a push‐out test in Instron machine and the failure mode was analyzed. One slice from each third was analyzed by confocal laser microscopy to evaluate the percentage of the perimeter of the root canal cross‐section with sealer tags and depth of tags. Data were analyzed by ANOVA, Kruskal–Wallis, and Tukey's tests (P < 0.05).

Results

Er,Cr:YSGG laser irradiation increased sealer bond strength to dentin, regardless of the final irrigation. The highest values were obtained for 3 W (4.02 ± 1.32) and 4 W (4.18 ± 0.98) powers and different from the non‐irradiated group (2.64 ± 0.58) (P < 0.05). The 2 W irradiation produced similar results to 3 W and 4 W when associated with 17% EDTA. Final irrigation with 17% EDTAC provided higher bond strength (4.01 ± 1.02) compared with distilled water (3.11 ± 1.09) and 1% NaOCl (3.47 ± 1.18) (P < 0.05). The cervical third (4.01 ± 1.21) presented significantly higher bond strength than the apical third (3.04 ± 0.89). There was a greater percentage of adhesive and mixed failure. In the groups irradiated with 3 W [21.1 (14.1–27.7)] and 4 W [17.8 (11.9–23.7)], a greater depth of filling material tags was observed compared with the non‐irradiated group [12.9 (9.0–20.0)]. The greatest percentage of canal perimeter with sealer tags was observed in the irradiated groups, with no difference among them (P > 0.05). The temperature rise was proportional to the increase of laser power.

Conclusions

Er,Cr:YSGG laser irradiation increased the bond strength of an epoxy resin‐based sealer to root dentin, with greater formation of sealer tags for all tested powers, especially when combined with 17% EDTAC final irrigation; temperature rise during irradiation remained below the critical threshold biologically accepted. Lasers Surg. Med. 48:985–994, 2016. © 2016 Wiley Periodicals, Inc.
Anoctamin 10‐Related Autosomal Recessive Cerebellar Ataxia: Comprehensive Clinical Phenotyping of an Irish Sibship
Authors: Bogdanova‐Mihaylova Petya , Austin Neil , Alexander Michael D. , Cassidy Lorraine , Early Anne , Murphy Raymond P. , Murphy Sinéad M. , Walsh Richard A.
Published: July 2016

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The autosomal recessive cerebellar ataxias are a heterogeneous group of neurodegenerative disorders. Mutations in the anoctamin 10 gene (ANO10) recently have been identified as a cause of autosomal recessive spinocerebellar ataxia type 10. Comprehensive phenotypic data are provided on 3 siblings with homozygous ANO10 mutations, including detailed ocular and cognitive assessments and bladder involvement not previously described in the literature. Data also are provided on unblinded therapy with coenzyme Q10, previously reported as a possible therapy in ANO10‐related ataxia. A genetic diagnosis in this family was obtained through next‐generation sequencing techniques after over 10 years of expensive sequencing of individual genes using the traditional Sanger approach. Greater commercial availability of gene panels will improve the ability to obtain a genetic diagnosis in the uncommon “non‐Friedreich's” recessive ataxias. Clinical recognition of these recessive ataxic syndromes will also inevitably improve as the full phenotypic spectrum is identified.
Effect of organic montmorillonite on microstructure and properties of the OMMT/EVA/Asphalt composites
Authors: Xiao Xin Yan , Liu Wu , Zhang Deng Ke , Wan Cai Xia
Published: July 2016

In order to improve the aging resistance and rutting resistance of the asphalt, a novel OMMT/EVA/asphalt composite was prepared by using organic montmorillonite (OMMT) and ethylene vinyl acetate (EVA) as modifiers via melt blending method. The microstructure and morphology of the EVA/asphalt composites and the OMMT/EVA/asphalt composites were characterized by X‐ray diffraction (XRD) and fluorescence microscopy (FM), respectively. XRD patterns indicate that the layers of OMMT are peeled off, and an exfoliated structure is formed. FM images show that a network structure appears between EVA and asphalt. The properties of the OMMT/EVA/asphalt composites were investigated by storage stability test, rotating thin film oven test (RTFOT), and dynamic shear rheometer (DSR), respectively. The results show that OMMT/EVA/asphalt composites exhibit better storage stability and aging resistance than that of EVA‐modified asphalt. Moreover, the obtained composites also show an increase in softening point and complex modulus (G*), and a decrease in penetration and phase angle (δ), which indicate that the OMMT/EVA/asphalt composites display good rutting resistance, high elasticity, and superior anti‐cracking properties. POLYM. COMPOS., 39:1959–1966, 2018. © 2016 Society of Plastics Engineers
Structure‐based bioisosterism design, synthesis, insecticidal activity and structure–activity relationship (SAR) of anthranilic diamide analogues containing 1,2,4‐oxadiazole rings
Authors: Liu Qi , Zhu Rui , Gao Shang , Ma Shi‐Han , Tang Hai‐Jun , Yang Jian‐Jun , Diao Ya‐Mei , Wang Hong‐Lei , Zhu Hong‐Jun
Published: July 2016

BACKGROUND

Anthranilic diamide derivatives are among the most important classes of synthetic insecticides. Moreover, the 1,2,4‐oxadiazole heterocycle, a bioisostere of amide, has been extensively used in pesticides. In order to discover novel molecules with high insecticidal activities, a series of anthranilic diamide analogues containing 1,2,4‐oxadiazole rings were designed and synthesised.

RESULTS

A series of novel anthranilic diamide derivatives containing 1,2,4‐oxadiazole were obtained, and confirmed by 1H and 13C nuclear magnetic resonance and high‐resolution mass spectrometry. The structure of 3‐bromo‐N‐(4‐chloro‐2‐methyl‐6‐{3‐[(methylsulphonyl)methyl]‐1,2,4‐oxadiazol‐5‐yl}phenyl)‐1‐(3‐chloropyridin‐2‐yl)‐1H‐pyrazole‐5‐carboxamide was further characterised by X‐ray diffraction analysis. In addition, bioassays showed that most of the newly synthesised compounds displayed 100% mortality against Plutella xylostella at 100 mg L−1, and compound 3IIl showed 90% larvicidal activities at a concentration of 0.5 mg L−1. The LC50 value of 3IIl was 0.20 mg L−1, which indicated that it may be used as a potential leading compound for further structural optimisation. Furthermore, brief comparative molecular field analysis (CoMFA) models were established to study the structure–activity relationships (SARs) of the title compounds.

CONCLUSION

Compound 3IIl may be used as a potential leading compound for further structural optimisation, and SARs and CoMFA models could provide reliable clues for further structural optimisation. © 2016 Society of Chemical Industry
Poor Performance of a Retrofitted Downstream Bypass Revealed by the Analysis of Approaching Behaviour in Combination with a Trapping System
Authors: Ovidio M. , Dierckx A. , Bunel S. , Grandry L. , Spronck C. , Benitez J.P.
Published: July 2016

The implementation of fish downstream migration bypass systems is still a major challenge, and there is interest in validating the adequacy of different configurations of bypass devices. In the Amblève River (Belgium), a mobile 3.3‐m height dam feeds two principal Francis and one Francis micro‐turbine and is equipped with a modern vertical slot fish pass and a downstream bypass. The aim of this study was to test the bypass attraction and efficiency (i.e. percentage of fish that approach the entrance and use the bypass) for Atlantic salmon smolts. During three consecutive years, a total of 1346 smolts were equipped with a radio frequency identification tag and released from March to May upstream of the dam of Lorcé. The entrance of the downstream migration bypass was equipped with a radio frequency identification antenna in order to detect the smolts approaching. In 2014, a capture cage was also placed downstream the bypass to evaluate its efficiency. The mean percentage of detected smolts at the entrance varied from 26.2 to 39.7%. In 2014, 16.5% of the released smolts entered the bypass and were finally caught in the cage, representing 39% of the smolts detected at the entrance. More than 98% of the detections occurred during night (mainly between 9 pm and 3 am). The searching delay near the bypass entrance varied from less than 5 min to more than 5 days (median 4.3 min). Visual observation indicated a behavioural reluctance before entering the bypass, with a shift from positive to negative rheotaxy. Our results underline the difficulty to install retrofitted bypass system on old existing hydropower plants. Copyright © 2016 John Wiley & Sons, Ltd.
Evolutionary‐based packets classification for anomaly detection in web layer
Authors: Kozik Rafał , Choraś Michał , Hołubowicz Witold
Published: July 2016

In this paper, we propose a novel method for web layer anomaly detection. In contrast to the majority of other state of the art approaches, we do not adapt manually configured parsers or packet content type detection techniques to partition the request sent from clients to server. In our experiments, we showed that making certain assumptions about the request content types may lead to the degradation of the detection performance. Therefore, we proposed unsupervised algorithm for automated packet structure extraction. We formulate this as the optimisation problem that is solved by means of genetic algorithm. Moreover, on top of the request segmentation schema, we provide the set of algorithms that measure statistics and apply machine learning techniques to solve the classification problems. The effectiveness of our methods is proved by the results achieved on the extended benchmark database. Copyright © 2016 John Wiley & Sons, Ltd.
Restoration of Mitochondrial NAD+ Levels Delays Stem Cell Senescence and Facilitates Reprogramming of Aged Somatic Cells
Authors: Son Myung Jin , Kwon Youjeong , Son Taekwon , Cho Yee Sook
Published: July 2016

The fundamental tenet that aging is irreversible has been challenged by the development of reprogramming technology that can restore molecular and cellular age by reversing the progression of aging. The use of cells from aged individuals as sources for reprogramming or transplantation creates a major barrier in stem cell therapy with respect to cell quality and quantity. Here, we investigated the molecular features underlying senescence and rejuvenation during aged cell reprogramming and identified novel factors that can overcome age-associated barriers. Enzymes, such as nicotinamide nucleotide transhydrogenase (NNT) and nicotinamide mononucleotide adenylyltransferase 3 (NMNAT3), that control mitochondrial NAD+ levels appear to be susceptible to aging. In aged cells, mitochondrial NAD+ levels decrease, accompanied by reduced SIRT3 activity; these changes severely impede cell fate transition. However, in cells collected from aged p16 knockout mice, which exhibit delayed cellular senescence, no changes in NNT or NMNAT3 expression were found. Importantly, restoring mitochondrial NAD+ levels by overexpressing NNT and NMNAT3 enhanced reprogramming efficiency of aged somatic cells and extended the lifespan of human mesenchymal stem cells by delaying replicative senescence. These results demonstrate that maintenance of mitochondrial NAD+ levels is critical for reversing the mechanisms of aging and ensuring that cells collected from aged individuals are of high quality.
Surgical Outcomes of Thoracic Myelopathy Secondary to Ossification of Ligamentum Flavum in a Regional Hospital: A Primitive Report and Literature Review
Authors: Eleanor Wen , Ki Ho Ka , Kin Cheung Ka
Published: July 2016

Introduction

Symptomatic thoracic stenosis is an uncommon disease in contrast to cervical and lumbar stenosis. It has been reported that ossification of ligamentum flavum (OLF) is the most common cause of thoracic myelopathy in our locality.

Materials and Methods

All patients with symptomatic thoracic spinal stenosis secondary to OLF who underwent operative treatment in our institution between January 1999 and December 2013 were retrospectively reviewed for demographic data, causes, complications and surgical outcomes.

Results

Twenty-six patients who underwent surgical treatment for symptomatic OLF were followed up for an average period of 71.3 months. All patients received decompression with concomitant instrumented fusion in 2 patients (7.7%). In our series, we had 2 cases (7.7%) of early post-operative neurological deterioration secondary to haematoma formation. Four cases (15.4%) were complicated with cerebrospinal fluid leakage. Operative outcome was reported in Frankel classification and modified Japanese Orthopedic Association (JOA) scale for thoracic myelopathy. After operation, 8 patients (30.8%) showed improvement in their Frankel grade, while 16 patients (61.5%) had no change and 2 patients (7.7%) reported deterioration. Mean JOA score showed significant improvement from 5.1 (range 2–8) to 6.9 post-operatively (range 2–11).

Discussion and Conclusion

OLF is the most common cause of thoracic myelopathy in our locality. Early accurate diagnosis and adequate surgical decompression are important for favourable outcomes despite operative difficulties and possible complications.
Translational Perspective on the Role of Testosterone in Sexual Function and Dysfunction
Authors: Podlasek Carol A. , Mulhall John , Davies Kelvin , Wingard Christopher J. , Hannan Johanna L. , Bivalacqua Trinity J. , Musicki Biljana , Khera Mohit , González-Cadavid Nestor F. , Burnett Arthur L.
Published: July 2016

Introduction

The biological importance of testosterone is generally accepted by the medical community; however, controversy focuses on its relevance to sexual function and the sexual response, and our understanding of the extent of its role in this area is evolving.

Aim

To provide scientific evidence examining the role of testosterone at the cellular and molecular levels as it pertains to normal erectile physiology and the development of erectile dysfunction and to assist in guiding successful therapeutic interventions for androgen-dependent sexual dysfunction.

Methods

In this White Paper, the Basic Science Committee of the Sexual Medicine Society of North America assessed the current basic science literature examining the role of testosterone in sexual function and dysfunction.

Results

Testosterone plays an important role in sexual function through multiple processes: physiologic (stimulates activity of nitric oxide synthase), developmental (establishes and maintains the structural and functional integrity of the penis), neural (development, maintenance, function, and plasticity of the cavernous nerve and pelvic ganglia), therapeutically for dysfunctional regulation (beneficial effect on aging, diabetes, and prostatectomy), and phosphodiesterase type 5 inhibition (testosterone supplement to counteract phosphodiesterase type 5 inhibitor resistance).

Conclusion

Despite controversies concerning testosterone with regard to sexual function, basic science studies provide incontrovertible evidence for a significant role of testosterone in sexual function and suggest that properly administered testosterone therapy is potentially advantageous for treating male sexual dysfunction.
Ocular Jellyfish Stings: Report of 2 Cases and Literature Review
Authors: Mao Chen , Hsu Chien-Chin , Chen Kuo-Tai
Published: July 2016

An ocular jellyfish sting is an ophthalmic emergency and is rarely reported in the medical literature. With the evolution of aquatic activities and entertainment in recent decades, we anticipate that more patients with ocular jellyfish stings may be taken to the emergency department. However, most physicians are unaware of the typical presentations, suitable treatments, prognosis, and possible complications of ocular jellyfish stings. We reported 2 cases with ocular jellyfish stings and collected cases series from literature review. The most common clinical features of ocular jellyfish stings were pain, conjunctival injection, corneal lesion, and photophobia. All patients who sustained ocular stings did so during aquatic activities, and the best management at the scene was proper analgesics and copious irrigation of affected eyes with seawater or saline. The ocular lesions were treated with topical cycloplegics, topical steroids, topical antibiotics, topical antihistamines, and removal of nematocysts. The prognosis was good, and all patients recovered without any permanent sequelae. However, symptoms in some patients may last longer than 1 week. Reported complications included iritis, increased intraocular pressures, mydriasis, decreased accommodation, and peripheral anterior synechiae.
It's Not Just a Visit: Receiving Government Officials’ Visits and Firm Performance in China
Authors: Li Weiwen , Tsang Eric W. K. , Luo Danglun , Ying Qianwei
Published: July 2016

Drawing upon signaling theory, we propose that a specific form of non-market action, receiving government officials’ visits, reduces transaction costs between firms and their potential exchange partners and thus contributes to firms’ competitive advantage in China. We also contend that severity of information asymmetry and availability of alternative ways of reducing transaction costs moderate the relationship between receiving government officials’ visits and company financial performance in opposite directions. The former factor increases the ex ante value of receiving government officials’ visits and strengthens its positive impact on financial performance, while the latter factor decreases the ex post value of receiving government officials’ visits and reduces its positive impact. Our conceptual framework is supported by analyses that draw on a sample of listed manufacturing firms in China. Our study contributes to a more in-depth understanding of non-market actions in emerging economies, their contingencies, and their performance implications.
Asymptotic behavior of the node degrees in the ensemble average of adjacency matrix
Authors: HAYASHI YUKIO
Published: July 2016

Various important and useful quantities or measures that characterize the topological network structure are usually investigated for a network, then they are averaged over the samples. In this paper, we propose an explicit representation by the beforehand averaged adjacency matrix over samples of growing networks as a new general framework for investigating the characteristic quantities. It is applied to some network models, and shows a good approximation of degree distribution asymptotically. In particular, our approach will be applicable through the numerical calculations instead of intractable theoretical analyses, when the time-course of degree is a monotone increasing function like power law or logarithm.
Systems biology analyses of the dynamic host response to Toxoplasma gondii infection in a murine model
Authors: KHO MEE TECK , CHONG CHUN WIE , LIM ERIN SWEE HUA , ISMAIL NOR HADIANI , DRAPER LACHLAN OLIVER , YAM WAI KEAT , LIM PATRICIA KIM CHOOI , MAK JOON WAH , YAP IVAN K. S.
Published: July 2016

Toxoplasmosis affects a third of the global population and is of particular concern for immunologically compromised individuals. Toxoplasmosis induces host physiological events ranging from immunological to metabolic responses across multiple biological compartments. To understand the sequence of host responses during acute and chronicToxoplasma gondiiinfection, eight male BALB/c mice were infected with 2000T. gondiiME49 tachyzoites with a further eight uninfected mice used as controls. Plasma cytokines status, urinary metabolic profiling and fecal microbial profiles were characterized to monitor temporal variation related toT. gondiiinfection. The results showed elevated serum interferon-γ(IFN-γ), interleukin-12p40 and  necrosis factor-αduring acute phase of infection with concomitant perturbation in host energy metabolism and host-gut microbiome co-metabolism of phenolics and a shift in microbial composition. However, the differences were less pronounced during the putative chronic phase of infection with elevated IFN-γ, differences in urinaryN-acetyls andO-acetyls of glycoproteins with no shift in gut microbial composition. Structural equation modelling on the current data showed host immune responses as the main driver for changes observed in urinary metabolites and gut microbial composition. Such an approach can be applied to other models of infectious diseases to aid understanding of host–pathogen interactions and potential biomarker discovery.
Stochastic domination and Markovian couplings
Authors: López F. Javier , Martínez Servet , Sanz Gerardo
Published: July 2016

For continuous-time Markov chains with semigroups P, P' taking values in a partially ordered set, such that P ≤ stP', we show the existence of an order-preserving Markovian coupling and give a way to construct it. From our proof, we also obtain the conditions of Brandt and Last for stochastic domination in terms of the associated intensity matrices. Our result is applied to get necessary and sufficient conditions for the existence of Markovian couplings between two Jackson networks.
Fractional diffusion and fractional heat equation
Authors: Angulo J. M. , Ruiz-Medina M. D. , Anh V. V. , Grecksch W.
Published: July 2016

This paper introduces a fractional heat equation, where the diffusion operator is the composition of the Bessel and Riesz potentials. Sharp bounds are obtained for the variance of the spatial and temporal increments of the solution. These bounds establish the degree of singularity of the sample paths of the solution. In the case of unbounded spatial domain, a solution is formulated in terms of the Fourier transform of its spatially and temporally homogeneous Green function. The spectral density of the resulting solution is then obtained explicitly. The result implies that the solution of the fractional heat equation may possess spatial long-range dependence asymptotically.
Overflow behavior in queues with many long-tailed inputs
Authors: Mandjes Michel , Borst Sem
Published: July 2016

We consider a fluid queue fed by the superposition of n homogeneous on-off sources with generally distributed on and off periods. The buffer space B and link rate C are scaled by n, so that we get nb and nc, respectively. Then we let n grow large. In this regime, the overflow probability decays exponentially in the number of sources n. We specifically examine the scenario where b is also large. We obtain explicit asymptotics for the case where the on periods have a subexponential distribution, e.g., Pareto, Lognormal, or Weibull.

The results show a sharp dichotomy in the qualitative behavior, depending on the shape of the function v(t) := - logP(A* > t) for large t, A* representing the residual on period. If v(.) is regularly varying of index 0 (e.g., Pareto, Lognormal), then, during the path to overflow, the input rate will only slightly exceed the link rate. Consequently, the buffer will fill ‘slowly’, and the typical time to overflow will be ‘more than linear’ in the buffer size. In contrast, if v(.) is regularly varying of index strictly between 0 and 1 (e.g., Weibull), then the input rate will significantly exceed the link rate, and the time to overflow is roughly proportional to the buffer size.

In both cases there is a substantial fraction of the sources that remain in the on state during the entire path to overflow, while the others contribute at their mean rates. These observations lead to approximations for the overflow probability. The approximations may be extended to the case of heterogeneous sources. The results provide further insight into the so-called reduced-load approximation.
Obituary: Georges Matheron
Authors: Jeulin Dominique
Published: July 2016

The scientific community is saddened to learn of the death of Professor Georges Matheron on 7 August 2000. As a major figure in applied mathematics over four decades, he leaves an outstanding scientific heritage, covering a wide range of domains where probabilistic tools and models are implemented. He also trained more than one generation of researchers, engineers and teachers. In the fields of theoretical and applied random media and image analysis his work has inspired many researchers worldwide: mathematicians, statisticians, physicists, experimentalists, earth scientists, mining engineers and also users of image analysis and synthesis in all its applications (materials, biology, artificial vision, CAD, remote sensing, geophysics, biometry, image coding etc.).
Spectrally negative Lévy processes with applications in risk theory
Authors: Yang Hailiang , Zhang Lianzeng
Published: July 2016

In this paper, results on spectrally negative Lévy processes are used to study the ruin probability under some risk processes. These processes include the compound Poisson process and the gamma process, both perturbed by diffusion. In addition, the first time the risk process hits a given level is also studied. In the case of classical risk process, the joint distribution of the ruin time and the first recovery time is obtained. Some results in this paper have appeared before (e.g., Dufresne and Gerber (1991), Gerber (1990), dos Reis (1993)). We revisit them from the Lévy process theory's point of view and in a unified and simple way.
A stochastic algorithm to compute optimal probabilities in the chaos game
Authors: Morato Laura M. , Siri Paola
Published: July 2016

We present a stochastic algorithm which generates optimal probabilities for the chaos game to decompress an image represented by the fixed point of an IFS operator. The algorithm can be seen as a sort of time-inhomogeneous regenerative process. We prove that optimal probabilities exist and, by martingale methods, that the algorithm converges almost surely. The method holds for IFS operators associated with any arbitrary number of possibly overlapping affine contraction maps on the pixels space.
Modelling correlated arrivals with a phase-type process
Authors: Latouche Guy
Published: July 2016

One considers semi-Markov processes using phase-type distributions, such that the marginal distribution of the interevent times are identically distributed but not independent. By suitably choosing the phase-type distributions, one obtains an exponential marginal distribution.
Computation of stationary probabilities of a Markovian system consisting of nearly independent subsystems
Authors: Takahashi Yukio
Published: July 2016

A numerical method is proposed for computing the stationary probabilities of a Markovian system consisting of two subsystems with slight interrelation. It exploits the independent features of the subsystems for evaluating the effects of their interrelation. In a test with a simple example, the numerical method proposed required less computational burden than other common numerical methods.
Stochastic calculus of variations
Authors: Fleming Wendell H.
Published: July 2016

We consider an analogue of classical calculus of variations, in which deterministic comparison curves are replaced by stochastic processes xt, of the form with ut a control applied at time t and wt a brownian motion. Connections with stochastic mechanics and non-linear filtering are discussed, as well as the deterministic limit as λ → 0.
Connections between optimal stopping and stochastic control I. Monotone follower problems
Authors: Karatzas Joannis , Shreve Steven E.
Published: July 2016

The stochastic control problem of tracking a Brownian motion by a non-decreasing process (monotone follower) is related to a question of optimal stopping. Direct probabilistic arguments are employed to show that the two problems are equivalent and that both admit optimal solutions.
Section means, integral transforms, and Boolean models
Authors: Goodey Paul , Kiderlen Markus , Well Wolfgang
Published: July 2016

For a stationary particle process X with convex particles in ℝdd ≧ 2, a mean body M(X) can be defined by where h(M,·) denotes the support function of the convex body M, γ the intensity of X, and P0 is the distribution of the typical particle of X (a probability measure on the set of convex bodies with Steiner point at the origin). Replacing the support function h(M,·) by the surface area measure S(M,·) (see Schneider (1993), for the basic notions from convex geometry), we get the Blaschke body B(X) of X, After normalization, the left-hand side represents the mean normal distribution of X. The main problem discussed here is whether B(X) (respectively S(B(X), ·)) is uniquely determined by the mean bodies M(X ∩ E) in random planar sections X ∩ E of X. From more general results in Weil (1995), it follows that the expectation ES(M(X ∩ E), ·) (taken w.r.t. the uniform distribution of two-dimensional subspaces E in ℝd) equals the surface area measure of a section mean B2(B(X)) of B(X). Thus, the formulated stereological question can be reduced to the injectivity of the transform B2 : K ↦ B2(K).
Part 1 — Introduction to the concept of axiomatic aerodynamic modelling
Authors: Hancock G. J. , Lam J. S. Y.
Published: July 2016

The aim of axiomatic aerodynamic modelling is introduced, namely to understand the validity of aerodynamic modelling in the context of aircraft dynamics with particular emphasis on understanding the relationship between full-scale flight behaviour as compared with that predicted from data based on wind tunnel tests.
A new boundary layer wind tunnel
Authors: Roach P. E.
Published: July 2016

The procedures employed for the design of a closed-circuit, boundary layer wind tunnel are described. The tunnel was designed for the generation of relatively large-scale, two-dimensional boundary layers with Reynolds numbers, pressure gradients and free-stream turbulence levels typical of the turbomachinery environment. The results of a series of tests to evaluate the tunnel performance are also described. The flow in the test section is shown to be highly uniform and steady, with very low (natural) free-stream turbulence intensities. Measured boundary layer mean and fluctuating velocity profiles were found to be in good agreement with classical correlations. Test-section free-stream turbulence intensities are presented for grid-generated turbulence: agreement with expectation is again found to be good. Immediate applications to the tunnel include friction drag reduction and boundary layer transition studies, with future possibilities including flow separation and other complex flows typical of those found in gas turbines.
A guide to classical flutter
Authors: Niblett L. T.
Published: July 2016

First essentials of classical flutter are demonstrated by a comprehensive study of the behaviour of a lifting surface with two degrees of freedom under the action of airforces limited to those in phase with displacement. Structural coupling between the coordinates is eliminated by taking the normal modes to be the deflection coordinates, and this results in conditions for stability with particularly concise forms. It is shown that the flutter stability can be seen to be very much a matter of the relative amplitudes of heave and pitch in the normal modes.

In-quadrature airforces are then introduced and it is shown that they have little effect when the flutter is severe. They are of more importance in the milder forms of flutter, the extreme of which are shown to be little different from instabilities in a single degree of freedom.
Computational analysis of unsteady supersonic cavity flows driven by thick shear layers
Authors: Zhang X. , Edwards J. A.
Published: July 2016

Supersonic cavity flows driven by a thick shear layer at Mach 1·5 and 2·5 are studied by solving the two-dimensional unsteady compressible Navier-Stokes equations in terms of mass-averaged variables. The length to depth ratio of the rectangular cavity is three. The numerical scheme used is the finite-difference algorithm by Brailovskaya. A two-layer eddy-viscosity turbulence model is used. The results are compared with experimental data. The computations show the self-sustained oscillations at Mach 1·5 and 2·5. The continuous formation and downstream shedding of leading edge vortices is demonstrated. The oscillatory modes are correctly predicted. The first mode is attributed to a large unsteady trailing edge vortex moving in the transverse direction. Based on the analysis, it is considered that the oscillation in the length to depth ratio three cavity is a longitudinal one and is controlled by a fluid dynamic mechanism rather than a purely acoustic one.
The relation between losses and entry-flow conditions in short dump diffusers for combustors
Authors: Klein A.
Published: July 2016

An experimental correlation is presented between the losses and the inlet flow conditions in short dump diffusers for turbojet combustors. Cascades of compressor blades upstream of the diffuser were used to make the flow field at inlet similar to that in a real jet engine. The flow field was altered in two ways — by varying the distance between the cascades and the diffuser inlet plane and by changing the blade aspect ratio. The measurements show clearly that distortions in the radial direction affect the losses to a much larger extent than non-uniformities in the circumferential direction. In consequence, the performance can be correlated to a satisfactory degree of accuracy simply by using the radial blockage factor at inlet.
The boundary element method for analysing repair patches on cracked finite sheets
Authors: Young A. , Cartwright D. J. , Rooke D. P.
Published: July 2016

The boundary element method is combined with the method of compatible deformations to obtain stress intensity factors for a cracked sheet reinforced with a repair patch. The method is applied to the analysis of a circular patch over a central crack in a rectangular uniaxially stressed sheet. It is shown that the proximity of the edges of the sheet to the patch edge has a negligible effect on the stress intensity factor of a crack completely under the patch.
The air-injection method of fixing boundary-layer transition and investigating scale effects
Authors: Ashill P. R. , Fulker J. L. , Weeks D. J.
Published: July 2016

The paper describes the air-injection method of fixing transition in wind-tunnel tests on a two-dimensional aerofoil and a swept panel at high subsonic free-stream speeds. The method is shown to provide a repeatable level of disturbance which, for a given flow condition, may be generated without interrupting the test and which appears not to cause a significant excess drag. Examples are given illustrating the effectiveness of the technique in demonstrating scale-sensitive features of flows, and a correlation is presented which allows the minimum value of air-injection mass flow needed to fix transition to be estimated from a knowledge of the behaviour of natural laminar flow on the wing.
Flow visualisation on rolling models using minitufts
Authors: O'Leary C. O. , Drew W.
Published: July 2016

Minitufts are increasingly used for flow visualisation on static wind tunnel models because they can be applied in larger numbers for increased detail and with less interference compared with conventional tufts. This Memorandum describes an extension of their use to continuously rotating models where the heavier conventional tufts are inadequate.

Tests on two combat aircraft models in the 4 m x 2.7 m Low Speed Wind Tunnel are described. Measured variations of rolling moment are explained with the aid of the minituft photographs.
Stress analysis of a cylindrical shell with a variable wall thickness
Authors: Chehil D. S. , Jategaonkar R. , Dhaliwal R. S.
Published: July 2016

While the bending analysis of cylindrical containers with wall thickness varying linearly has attracted much attention, it seems the general variation in wall thickness has not been considered. This is because of the difficulties which have been encountered due to the complex nature of the differential equations involved. In this paper, the container’s wall thickness is chosen to be of general variation and the differential equation is perturbed to give rise to a sequence of differential equations. It is shown that this sequence can be easily solved when the form of variation in wall thickness is specified. A complete solution is obtained in a particular case when the wall thickness varies linearly and the tank is subjected to hydrostatic pressure. For this particular case the numerical results are compared with the ones available in the literature which seem to be in good agreement.
The use of reliability techniques in civil aircraft structural airworthiness — a CAA view
Authors: James D. O. N.
Published: July 2016

The safety of civil aircraft is regulated through a process of airworthiness certification and the application of operational regulations. The main elements of airworthiness are:

(i) certification of the design,

(ii) compliance with airworthiness requirements,

(iii) maintenance and reaction to service problems -continued airworthiness.

The airworthiness requirements are developed through a process of discussion and consultation with all interested parties. Whilst the result is largely a consensus view, the ultimate authority rests with the airworthiness authority. In recent years there have been increased efforts to reduce national differences with the aim of producing a single international code. At present there are two, with European and US international pressures tending to work against ‘improving’ requirements unless there is a clearly recognised need.
A summary of measurements of steady and oscillatory pressures on a rectangular wing
Authors: Mabey D. G. , Welsh B. L. , Pyne C. R.
Published: July 2016

This paper describes a series of steady and time-dependent pressure measurements on a half-model of a rectangular wing of aspect ratio 4. The wing was mounted on a half-body attached to a sidewall of the RAE 8 x 8 ft wind tunnel and the tests were made at Mach numbers of 0·20, 0·42, 0·70, 0·80 and 0·85 with fixed transition and a Reynolds number of about 2·5 x 106at the highest Mach number. The wing was oscillated about its mid-chord axis at four frequencies giving frequency parameters up to 1·15 at M = 0·20 and 0·25 at M = 0·85. The static angle of incidence was varied from –10° to + 10°.

Selected mean and oscillatory measurements are offered as a challenge to computational fluid dynamicists for this simple three-dimensional configuration. Comparisons are made with calculations by means of subsonic linearised theory and recent transonic small perturbation methods. The measurements are of particular interest at transonic speeds, where both attached and incipient separated flows are considered.
Comparison of Euler and Navier-Stokes solutions for vortex flow over a delta wing
Authors: Rizzi A. , Müller B.
Published: July 2016

A numerical method has been developed recently to solve the Navier-Stokes equations for laminar compressible flow around delta wings. A large-scale Navier-Stokes solution on a mesh of 129 × 49 × 65 points for transonic flow Mx = 0·85, α = 10° and Rex = 2·38 × 106 around a 65° swept delta wing with round leading edge is presented and compared with a correspondingly large-scale Euler solution. The viscous results reveal the presence of primary, secondary, and even tertiary vortices. The starting location of the primary vortex is seen to be quite different in the two solutions. In the viscous solution it starts at the wing apex, but in the Euler results it starts about one quarter chord downstream. The secondary reparations are also different, due to the up-lifting of the boundary layer in the viscous results, but to a cross-flow shock in the Euler computation. Comparison with experiment shows that the interaction between the primary and secondary vortices in the Navier-Stokes computation is obtained correctly and that these results are a more realistic simulation than the one given by the Euler equations.
Possible types of flow on lee-surface of delta wings at supersonic speeds
Authors: Seshadri S. N. , Narayan K. Y.
Published: July 2016

Experiments were conducted to study the types of flow that occur on the lee surface of delta wings at supersonic speeds. Two sets of flat topped delta wings of different thickness (wedges with 10° and 25° normal angle respectively), each with leading edge sweep angles of 45°, 50°, 60° and 70°, were tested. The measurements, carried out at Mach numbers of 1·4, 1·6, 1·8, 2·0, 2·5 and 3·0, included oil flow visualisations (on both sets of wings) and static pressure distributions (on the thicker wing only). In addition, a 60° sweptback delta wing with a normal angle of 40° was also tested. The tests on this wing included both oil flow visualisations and static pressure measurements. From these and other existing measurements, the leeside flows have been classified into nine distinct types, namely (i) leading edge separated flow with secondary separation, (ii) leading edge separated flow with secondary and tertiary separation, (iii) leading edge separated flow with a shock wave beneath the primary vortex, (iv) leading edge separated flow with shock-induced secondary separation, (v) fully attached flow, (vi) flow attached at the leading edge with inboard shock-induced separation, (vii) mixed type of flow, (viii) flow with a leading edge separation bubble and (ix) leading edge separated flow with a shock wave lying on the lee surface in between the leading edge vortices. These types of flow have been displayed in a plane of Mach number and angle of attack normal to the leading edge. The experimental results indicate that increasing wing thickness has no qualitative effect on the types of flow observed but does shift the boundaries between some of the types of flow.
Introductory remarks
Authors: Smith J. H. B.
Published: July 2016

On the afternoon of 14th April 1987, the Society held a half-day symposium on wing-tip flows and devices. Papers were presented by J. J. Spillman of Cranfield Institute of Technology on wing-tip sails, by A. C. Willmer of British Aerospace (in association with R. V. Barrett and J. D. Coleman of Bristol University) on the tip flow of part-span flaps, and by H. P. Horton of Queen Mary College on measurements in the viscous flow regions of streamlined tips. Written versions of two of these talks and a synopsis of the third* have been prepared and are being printed in theJournalfollowing these introductory remarks. The contribution by J. S. Smith of RAE to the discussion session is appearing elsewhere.