bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of low‐level laser therapy on pain and perineal healing after episiotomy: A triple‐blind randomized controlled trial
Authors: Alvarenga Marina B. , de Oliveira Sonia Maria Junqueira Vasconcellos , Francisco Adriana A. , da Silva Flora Maria B. , Sousa Marcelo , Nobre Moacyr Roberto
Published: July 2016

Background and Objective

Episiotomy is associated with perineal pain and healing complications. The low‐level laser therapy (LLLT) reduces pain and inflammation and stimulates the healing process. This study aimed to assess the effect of LLLT on pain and perineal healing after an episiotomy.

Design/Materials and Methods

A randomized, triple‐blind, parallel clinical trial with 54 postpartum women who had a spontaneous birth with a right mediolateral episiotomy. The women were randomized into two groups: the experimental group (applications of LLLT n = 29) or the placebo group (simulated LLLT applications n = 25). Three sessions of real or sham irradiation were performed at 6–10 hours after normal birth, and the 2nd and 3rd applications were performed at 20–24 hours and 40–48 hours after the first session, respectively. Perineal pain was recorded using a Numeric Scale ranging from 0 to 10 (0 = absence and 10 = worst pain). Perineal healing was assessed using the redness, oedema, ecchymosis, discharge, and approximation (REEDA) scale. Both groups were assessed four times: in each of the three LLLT sessions and at 7–10 days after normal birth. The groups were compared using the Student's t, Mann–Whitney, and Chi‐square tests.

Results

There was no significant difference between the groups regarding perineal healing after LLLT. The perineal pain scores were statistically higher in the experimental group in the first assessment and after the third LLLT. There was no significant difference between the groups related to the perineal pain scores 7–10 days after normal birth.

Conclusion

The use of LLLT does not provide any benefit for treating postpartum perineal trauma using these specific protocol and parameters. Lasers Surg. Med. 49:181–188, 2017. © 2016 Wiley Periodicals, Inc.
Quantifying Structural and Solid‐State Viscoelastic Properties of Poly(propylene) (PP)/Poly(oxymethylene) (POM) Blend Films
Authors: Kasgoz Alper , Akın Dincer , Durmus Ali
Published: July 2016

In this study, isotactic poly(propylene) (PP)/poly(oxymethylene) (POM) blend films, including of POM as minor phase in the range of 10–30 wt%, are prepared in a twin screw extruder equipped with a slit‐die and cast film haul‐off unit. It is found that the blend films show characteristic immiscible matrix‐droplet morphology. Short‐term uniaxial tensile creep behaviors of films imply that the introducing of POM significantly improves the elastic modulus and decreases the total creep strain of PP/POM blends. Creep tests are also performed at various temperatures and long‐term deformations of samples are predicted by applying of time‐temperature superposition principle and the Findley model. It is found that the presence of POM domains into PP matrix enhances the creep resistance of PP especially at high temperatures. It is concluded that the PP‐rich PP/POM blend films show much lower short and long‐term creep strains compared to PP.

image
Postural, Bone, and Joint Disorders in Parkinson's Disease
Authors: Rabin Marcie L. , Earnhardt Mary Cathryn , Patel Anvi , Ganihong Ivana , Kurlan Roger
Published: July 2016

Background

Stooped posture was mentioned in the original description of the characteristic features of Parkinson's disease (PD). Since then, a variety of postural, bone, and joint problems have become recognized as common aspects of the illness and deserve attention.

Methods

A Medline literature search for the period from 1970 to 2016 was performed to identify articles relevant to this topic. Keywords for the search included posture, spine, bone disorders, fractures, joint disorders, kyphosis, scoliosis, stooping, camptocormia, Pisa syndrome, frozen shoulder, anterocollis, dropped head syndrome, and pain in combination with PD. The articles were then reviewed to summarize clinical features, frequency, impact, pathophysiology, and treatment options for these conditions.

Results

Postural disorders (kyphoscoliosis, camptocormia, Pisa syndrome, dropped head syndrome), bone mineralization disorders (osteoporosis, bone fractures), and joint disorders (frozen shoulder, dystonia involving joints, joint pain) are often seen in association with PD. Treatment options for these conditions are varied and may include medications, physical therapy, or surgical interventions.

Conclusions

Posture, bone, and joint disorders are common in patients with PD; they often produce added disability, and they may be treatable.
Conservation laws and double reduction of (2+1) dimensional Calogero–Bogoyavlenskii–Schiff equation
Authors: San Sait , Akbulut Arzu , Ünsal Ömer , Taşcan Filiz
Published: July 2016

In this paper, we obtain conservation laws of (2+1) dimensional Calogero–Bogoyavlenskii–Schiff equation by non‐local conservation theorem method. Besides, exact solutions are obtained by the aid of the symmetries associated with conservation laws. Double reduction is used to obtain these exact solution of Calogero–Bogoyavlenskii–Schiff equation. Copyright © 2016 John Wiley & Sons, Ltd.
Contracts and coordination: Supply chains with uncertain demand and supply
Authors: He Yong , Zhao Xuan
Published: July 2016

Considering a supply chain with a supplier subject to yield uncertainty selling to a retailer facing stochastic demand, we find that commonly studied classical coordination contracts fail to coordinate both the supplier's production and the retailer's procurement decisions and achieve efficient performance. First, we study the vendor managed inventory (VMI) partnership. We find that a consignment VMI partnership coupled with a production cost subsidy achieves perfect coordination and a win‐win outcome; it is simple to implement and arbitrarily allocates total channel profit. The production cost subsidy optimally chosen through Nash bargaining analysis depends on the bargaining power of the supplier and the retailer. Further, motivated by the practice that sometimes the retailer and the supplier can arrange a “late order,” we also analyze the behavior of an advance‐purchase discount (APD) contract. We find that an APD with a revenue sharing contract can efficiently coordinate the supply chain as well as achieve flexible profit allocation. Finally, we explore which coordination contract works better for the supplier vs. the retailer. It is interesting to observe that Nash bargaining solutions for the two coordination contracts are equivalent. We further provide recommendations on the applications of these contracts. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 305–319, 2016
Hybrid stress quadrilateral finite element approximation for stochastic plane elasticity equations
Authors: Xu Xiaojing , Fan Wenwen , Xie Xiaoping
Published: July 2016

This paper considers stochastic hybrid stress quadrilateral finite element analysis of plane elasticity equations with stochastic Young's modulus and stochastic loads. Firstly, we apply Karhunen–Loève expansion to stochastic Young's modulus and stochastic loads so as to turn the original problem into a system containing a finite number of deterministic parameters. Then we deal with the stochastic field and the space field by k−version/p−version finite element methods and a hybrid stress quadrilateral finite element method, respectively. We derive a priori error estimates, which are uniform with respect to the Lamè constant λ∈(0,+∞). Finally, we provide some numerical results. Copyright © 2016 John Wiley & Sons, Ltd.
College recovers from the brink of collapse to post record‐setting enrollment numbers
Authors: Sutton Halley
Published: July 2016

In 2014, Montreat College was on the verge of either a merger or a complete shutdown. It was only through the intervention of an anonymous $6 million donation in March of 2014 that Montreat was able to put into place needed changes to ensure that the campus not only survived, but thrived. Now, a little over two years later, the small private Christian college in North Carolina is enjoying strong enrollment and aspiring to grow. Last fall, the college enrolled its highest number of new students since its founding in 1916, for a total of 1,000 students on campus. Officials now seek to double that enrollment within the next four years. Paul J. Maurer, president of Montreat, shared insights about what has helped advance the institution into a healthy position, including the expansion and addition of programs geared toward adult learners.
Randomized, double‐blind, placebo‐controlled study of methylphenidate for the treatment of depression in SSRI‐treated cancer patients receiving palliative care
Authors: Sullivan Donald R. , Mongoue‐Tchokote Solange , Mori Motomi , Goy Elizabeth , Ganzini Linda
Published: July 2016

Objective

To determine the effectiveness of methylphenidate for depression treatment in patients with advanced cancer.

Design

An 18‐day randomized, double‐blind, placebo‐controlled clinical trial of methylphenidate for treatment of depression in selective serotonin reuptake inhibitor‐treated patients with advanced cancer in hospice or receiving palliative care. The primary outcome was depression remission, defined as a ≥50% reduction in score on the Montgomery‐Asberg Depression Rating Scale.

Results

Among 47 enrolled participants, 34 were randomized. At study day 18, 85% of the methylphenidate and 60% of the placebo group were in depression remission (P = .22). Mean time to depression remission was 10.3 days [standard error (SE) 1.8] in the methylphenidate and 8.1 (SE 1.3) in the placebo group (P = .48). The mean baseline score for the Hospital Anxiety and Depression Scale (HADS) was 10.4 in each group and decreased by 3.6 (SE 1.1) in the methylphenidate and 2.3 (SE 1.2) in the placebo group (P = .51) by day 18. Once in remission, 1 methylphenidate and 5 placebo participants relapsed to depression (P = .18). There was no difference in mortality between the groups during the trial. Trial results were limited by small sample size attributed to difficulties in recruiting terminally ill patients.

Conclusions

This trial failed to demonstrate that methylphenidate treatment in selective serotonin reuptake inhibitor‐treated patients had a significant effect on depression remission in patients with advanced cancer. This study underscores the difficulties in conducting trials for symptom management in patients with shortened life expectancy.
Through‐layer XPS investigations of the Si3N4/AlGaN interface
Authors: Reiner Maria , Denifl Guenter , Stadtmueller Michael , Pietschnig Rudolf , Ostermaier Clemens
Published: July 2016

Investigations of chemical species at the dielectric/III‐N interface remain an important question in order to understand the chemical origin of the surface states, which are present at the heterostructure surface. In this work, we demonstrate a sample preparation technique to analyze the existing interface species by X‐ray photoelectron spectroscopy (XPS) through thin uniform silicon nitride (Si3N4) layers 1.4 ± 0.2 nm. We show that it is crucial that the layers are as thin as possible but as thick as necessary to avoid oxygen diffusion through the passivation. Due to the sufficient information depth provided by such layers, the photoelectrons are detected. This is an advantage over sputtering as no intermixing of atoms or cleavage of bonds occurs. We show that the deposited Si3N4 hinders oxygen diffusion through the layer to the AlGaN surface. Selective SiO2 over Si3N4 etching and XPS depth profiles indicate that ∼1 nm of the thin Si3N4 layer has formed a surface oxide. Angle‐resolved XPS measurements confirm the accumulation of oxygen at the top and bottom Si3N4 interfaces. No indication is found that interfacial oxygen is bound to any other than the group‐13 metal. In agreement with the HSAB concept, the interfacial oxygen is bound to Al rather than Ga.

Scheme of the nondestructive XPS interface analysis of the dielectric/AlGaN interface.
Fully digital BPSK demodulator for satellite supressed carrier telecommand system
Authors: Pereira de Lucena Antonio Macilio , Prudêncio de Almeida Filho Magno , Gomes de Figueredo Caio , Braga Pimentel Diego , Sales do Nascimento Rios Clauson , Tavares Ferreira da Silva Francisco de Assis
Published: July 2016

In this paper, we present the design of a fully digital binary phase shift keying demodulator for application in satellite high‐rate suppressed carrier telecommand system. The proposed system digitalizes the received signal in the intermediate frequency stage using bandpass sampling technique, and the resulting baseband signal is used to synchronization of symbol and phase and to bit detection. The design of all functional modules is presented in details. Another innovation presented in this work is the inclusion of a non‐linearity in the phase synchronizer module to permit its operation independent from the signal amplitude. Moreover, aiming the characterization and performance evaluation of the system, we do some original mathematical analyses. Finally, test results show that the demodulator complies all the project requirements, and the prototype implementation loss, in terms of bit energy to noise power density ratio, is less than 0.3 dB. Copyright © 2016 John Wiley & Sons, Ltd.
Resource requests prediction in the cloud computing environment with a deep belief network
Authors: Zhang Weishan , Duan Pengcheng , Yang Laurence T , Xia Feng , Li Zhongwei , Lu Qinghua , Gong Wenjuan , Yang Su
Published: July 2016

Accurate resource requests prediction is essential to achieve optimal job scheduling and load balancing for cloud Computing. Existing prediction approaches fall short in providing satisfactory accuracy because of high variances of cloud metrics. We propose a deep belief network (DBN)‐based approach to predict cloud resource requests. We design a set of experiments to find the most influential factors for prediction accuracy and the best DBN parameter set to achieve optimal performance. The innovative points of the proposed approach is that it introduces analysis of variance and orthogonal experimental design techniques into the parameter learning of DBN. The proposed approach achieves high accuracy with mean square error of [10−6,10−5], approximately 72% reduction compared with the traditional autoregressive integrated moving average predictor, and has better prediction accuracy compared with the state‐of‐art fractal modeling approach. Copyright © 2016 John Wiley & Sons, Ltd.
Bio‐/Chemosensors and Imaging with Aggregation‐Induced Emission Luminogens
Authors: Zhan Chi , You Xue , Zhang Guanxin , Zhang Deqing
Published: July 2016

Aggregation‐induced emission (AIE) luminogens show abnormal fluorescent behavior; they are non‐emissive in solution, but they become strongly emissive after aggregation. Sensing and imaging are the major applications of AIE luminogens. By properly manipulating the aggregation and deaggregation of AIE molecules, various bio‐/chemosensors have been developed. Moreover, AIE molecules with targeting groups have been devised for imaging of organelles and cancer cells. In this account, we report our recent work on the application of AIE luminogens for the construction of bio‐/chemosensors and imaging.

image
Syntheses and Structures of Zinc Bis(phosphinimino)methanide Complexes
Authors: Bayram Melike , Gondzik Sebastian , Bläser Dieter , Wölper Christoph , Schulz Stephan
Published: July 2016

Reactions of bis(phosphinimino)methanes H2C(PPh2NR)2 [R = SiMe3 (L1H), Ph (L2H), 2,6‐iPr2‐C6H3 (DIPP) (L3H)] with ZnR2 (R = Me, Et) yielded the corresponding bis(phosphinimino)methanide zinc complexes LZnMe [L2 (1), L3 (2)] and LZnEt [L1 (3), L2 (4), and L3 (5)]. Complexes 1–5 were characterized by heteronuclear NMR (1H, 13C, 31P) and IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction.
Are the Current Size Options of Glenoid Baseplates for Reverse Shoulder Arthroplasty Sufficient for our Local Population?
Authors: Amy Cheung Yim Ling , Chester Lie Wai Hung , Lit Chow Hung , Lam Chan Wai , Kevin Wong Kwun Hung , Bong Woo Siu , Cheung Wong Wing
Published: July 2016

Background/Purpose

Reverse shoulder arthroplasty (RSA) is an effective treatment for patients who suffer from shoulder pain and dysfunction associated with a variety of shoulder pathologies including severe rotator cuff deficiency with or without glenohumeral arthritis. It has been widely used in European countries and the United States and is now gaining popularity in Asia, including Hong Kong. However, there are only limited size options available for glenoid baseplates, with 25 mm being the smallest size in some commonly used systems. The aim of our study is to perform computerized tomography (CT) measurements of the glenoid dimension in the Chinese population and to see if the current glenoid baseplate component size option is sufficient for our local population.

Methods

A total of 70 CT scans of shoulder regions were analysed. Measurements included maximum superoinferior height and the anteroposterior height.

Results

The glenoid dimensions were smaller compared to those from previous studies in Caucasian counterparts. Some 41% of female glenoids had widths measuring < 25 mm (25 mm being the smallest size available in some commonly used RSA systems).

Conclusion

Although there are only limited size options available for the glenoid baseplate in RSA, from our data, it should be able to cover most patients in our local population. However, surgeons should exercise special care when contemplating performing reverse shoulder replacement for small size females in our local population.
Impact of Testosterone Solution 2% on Ejaculatory Dysfunction in Hypogonadal Men
Authors: Maggi Mario , Heiselman Darell , Knorr Jack , Iyengar Smriti , Paduch Darius A. , Donatucci Craig F.
Published: July 2016

Introduction

Hypogonadism is defined as decreased testosterone levels in men. Hypogonadism can be accompanied by erectile, orgasmic, and ejaculatory dysfunction.

Aims

To evaluate whether treatment with testosterone solution 2% (testosterone) could improve ejaculatory function in a cohort of hypogonadal men.

Methods

Sexually active, hypogonadal men at least 18 years old (total testosterone < 300 ng/dL) were randomized to receive testosterone or placebo for 12 weeks.

Main Outcome Measures

Effects of testosterone on primary outcomes were evaluated using the International Index of Erectile Function (IIEF) and the Men's Sexual Health Questionnaire, Ejaculatory Dysfunction, Short Form (MSHQ-EjD-SF) questionnaires. Treatment differences were calculated using analysis of covariance.

Results

In total, 715 men (mean age = 55 years) were randomized to placebo (n = 357) or testosterone (n = 358). Most sexually active men who reported IIEF scores had some degree of erectile dysfunction (IIEF erectile function score < 26). Although ejaculatory function score (MSHQ-EjD-SF) improved in the testosterone group compared with placebo (P < .001), improvement on the “bother” item did not reach statistical significance. Treatment-related adverse events in the testosterone group affecting at least 1% of patients were increased hematocrit, upper respiratory tract infection, arthralgia, burning sensation, fatigue, increased prostate-specific antigen, erythema, and cough. Few patients in either treatment group developed at least one adverse event leading to discontinuation (testosterone = 1.98% vs placebo = 3.09%; P = .475).

Conclusion

Hypogonadal men receiving testosterone solution 2% therapy experience significantly greater improvement in ejaculatory function, compared with placebo, as assessed by the MSHQ-EjD-SF. However, improvement in “bother” was not statistically different between the two groups. Testosterone therapy was generally well tolerated.
Future Targets for Female Sexual Dysfunction
Authors: Farmer Melissa , Yoon Hana , Goldstein Irwin
Published: July 2016

Introduction

Female sexual function reflects a dynamic interplay of central and peripheral nervous, vascular, and endocrine systems. The primary challenge in the development of novel treatments for female sexual dysfunction is the identification and targeted modulation of excitatory sexual circuits using pharmacologic treatments that facilitate the synthesis, release, and/or receptor binding of neurochemicals, peptides, and hormones that promote female sexual function.

Aim

To develop an evidence-based state-of-the-art consensus report that critically integrates current knowledge of the therapeutic potential for known molecular and cellular targets to facilitate the physiologic processes underlying female sexual function.

Methods

State-of-the-art review representing the opinions of international experts developed in a consensus process during a 1-year period.

Main Outcome Measures

Expert opinion was established by grading the evidence-based medical literature, intensive internal committee discussion, public presentation, and debate.

Results

Scientific investigation is urgently needed to expand knowledge and foster development of future treatments that maintain genital tissue integrity, enhance genital physiologic responsiveness, and optimize positive subjective appraisal of internal and external sexual cues. This article critically condenses the current knowledge of therapeutic manipulation of molecular and cellular targets within biological systems responsible for female sexual physiologic function.

Conclusion

Future treatment targets include pharmacologic modulation of emotional learning circuits, restoration of normal tactile sensation, growth factor therapy, gene therapy, stem cell–based therapies, and regenerative medicine. Concurrent use of centrally and peripherally acting therapies could optimize treatment response.
al-Ghorab Shunt for Priapism
Authors: Müller Alexander
Published: July 2016

The Surgical Techniques Section is sponsored in part by Coloplast
Arabic toponymy in the territory of al-Bayḍāʾ / al-Qubba (Cyrenaica, Libya)
Authors: Lorenzo Jimenez Jesus
Published: July 2016

Toponymic records are a useful tool for establishing initial discriminating criteria before undertaking an archaeological survey of a given territory. This study deals with a series of toponyms in an area located in the region of Cyrenaica which are characterised by containing several terms, the first of which refers to anthropic elements related to some forms of settlement, in particular the formsqaṣr, sīraandqarya. First, a semantic study of the toponyms was conducted and then they were incorporated into a geographic information system (GIS) with a 3D base map, which provided information on their location and their relationship with the physical environment.
A Dynamic Typology of Informal Institutions: Learning from the Case ofGuanxi
Authors: Horak Sven , Restel Katja
Published: July 2016

Currently, the mechanism in which informal institutions, recently discovered as an influential, new paradigm in business and management studies interact with and shape formal institutions remains unclear. Helmke and Levitsky (2004) proposed an outcome-based typology for the interaction of informal institutions with formal ones. By using a structured approach for literature aggregation, we test the proposed typology of Helmke and Levitsky by applying this method to 74 empirical studies to investigate the influence ofguanxion formal institutions. We conclude thatguanxifits into none of the proposed categories perfectly. As a result, we propose the relationship betweenguanxiand formal institutions as auxiliary as well as competing concurrently, leading to convergent and divergent outcomes, respectively. Moreover, we propose a third category to add to the existing typology, namely ‘formal institutions in transition’. We furthermore incorporate a dynamic aspect to the model by adding two further categories, concerned with the direction of the development. We believe the resulting extension to the original typology of Helmke and Levitsky accurately accounts for the dynamic nature of informal institutions as well as their important role in shaping effective formal institutions.
Random fractals and probability metrics
Authors: Hutchinson John E. , Rüschendorf Ludger
Published: July 2016

New metrics are introduced in the space of random measures and are applied, with various modifications of the contraction method, to prove existence and uniqueness results for self-similar random fractal measures. We obtain exponential convergence, both in distribution and almost surely, of an iterative sequence of random measures (defined by means of the scaling operator) to a unique self-similar random measure. The assumptions are quite weak, and correspond to similar conditions in the deterministic case.

The fixed mass case is handled in a direct way based on regularity properties of the metrics and the properties of a natural probability space. Proving convergence in the random mass case needs additional tools, such as a specially adapted choice of the space of random measures and of the space of probability distributions on measures, the introduction of reweighted sequences of random measures and a comparison technique.
Alternative routeing in fully connected queueing networks
Authors: Laws C. N. , Teh Y. C.
Published: July 2016

We consider a fully connected queueing network in which customers have one direct and many alternative routes through the network, and where customer routeing is dynamic. We obtain an asymptotically optimal routeing policy, taking the limit as the number of queues of the network increases. We observe that good policies route customers directly, unless there is a danger of servers becoming idle, in which case customers should be routed alternatively so as to avoid such idleness, and this leads to policies that perform well in moderate-sized networks.
The number and sum of near-maxima for thin-tailed populations
Authors: Pakes Anthony G.
Published: July 2016

A near-maximum is an observation which falls within a distance a of the maximum observation in an i.i.d. sample of size n. The asymptotic behaviour of the number Kn(a) of near-maxima is known for the cases where the right extremity of the population distribution function is finite, and where it is infinite and the right hand tail is exponentially small, or fatter than exponential. This paper completes the picture for thin tails, i.e., tails which decay faster than exponential. Limit theorems are derived and used to find the large-sample behaviour of the sum of near-maxima.
Analysis of a phase transition phenomenon in packet networks
Authors: Mandjes Michel , Kim Jeong-Han
Published: July 2016

The multiplexing of variable bit rate traffic streams in a packet network gives rise to two types of queueing. On a small time-scale, the rates at which the sources send is more or less constant, but there is queueing due to simultaneous packet arrivals (packet-level effect). On a somewhat larger time-scale, queueing is the result of a relatively high number of sources sending at a rate that is higher than their average rate (burst-level effect). This paper explores these effects. In particular, we give asymptotics of the overflow probability in the combined packet/burst scale model. It is shown that there is a specific size of the buffer (i.e. the ‘critical buffer size’) below which packet-scale effects are dominant, and above which burst-scale effects essentially determine the performance—strikingly, there is a sharp demarcation: theso-called ‘phase transition’. The results are asymptotic in the number of sourcesn. We scale buffer spaceBand link rateCbyn, tonbandnc, respectively; then we letngrow large. Applying large deviations theory we show that in this regime the overflow probability decays exponentially in the number of sourcesn. For small buffers the corresponding decay rate can be calculated explicitly, for large buffers we derive an asymptote (linear inb). The results for small and large buffers give rise to an approximation for the decay rate (with generalb), as well as for the critical buffer size. A numerical example (multiplexing of voice streams) confirms the accuracy of these approximations.
Intrinsic volumes and Gaussian processes
Authors: Vitale Richard A.
Published: July 2016

Intrinsic volumes are key functionals in convex geometry and have also appeared in several stochastic settings. Here we relate them to questions of regularity in Gaussian processes with regard to Itô–Nisio oscillation and metrization of GB/GC indexing sets. Various bounds and estimates are presented, and questions for further investigation are suggested. From alternate points of view, much of the discussion can be interpreted in terms of (i) random sets and (ii) properties of (deterministic) infinite-dimensional convex bodies.
The performance of index-based policies for bandit problems with stochastic machine availability
Authors: Dunn R. T. , Glazebrook K. D.
Published: July 2016

We consider generalisations of two classical stochastic scheduling models, namely the discounted branching bandit and the discounted multi-armed bandit, to the case where the collection of machines available for processing is itself a stochastic process. Under rather mild conditions on the machine availability process we obtain performance guarantees for a range of controls based on Gittins indices. Various forms of asymptotic optimality are established for index-based limit policies as the discount rate approaches 0.
Processus de branchement en champ moyen et réaction PCR
Authors: Piau Didier
Published: July 2016

Sun and Waterman model DNA mutations during the PCR reaction by a non-canonical branching process. Mean-field approximated values fit the simulated values surprisingly well. We prove this as a theoretical result, for a wide range of the parameters. Thus, we bound explicitly the biases, in law and in the mean, that the mean-field approximation induces in the random number of mutations of a DNA molecule, as a function of the initial number of molecules, of the number of PCR cycles, of the efficiency rate and of the mutation rate. The range where we prove that the approximation is good contains the observed mutation rates in many actual PCR reactions.
A family of delay-dependent dynamic priority queueing systems
Authors: Reeser P. K.
Published: July 2016

We consider a family of single-server queueing systems with two priority classes. The system operates under a dynamic priority queue discipline in which the relative priorities of customers increase with their waiting times, and which can be characterized by the urgency number. We investigate the transient as well as the steady-state behavior of the virtual waiting times of the two classes of customer as functions of the urgency number. Stochastic orderings, the joint distribution, and surprising limit results for these processes are obtained for the first time.
Computational and probabilistic methods in cryptanalysis: the Kryha machine
Authors: Konheim Alan G.
Published: July 2016

In the early part of this century, a mechanical ‘ciphering machine’ was invented and marketed by a Berlin engineer, Alexander von Kryha. The Kryha machine performed a polyalphabetic substitution on text controlled by one of 1050 possible keys. In this lecture we describe the general principles of cryptanalysis and its interplay with probability theory and show how the Kryha machine may be cryptanalyzed.
Optimal replacement for self-repairing shock models by general failure rate
Authors: Gotilieb Gary , Levikson Benny
Published: July 2016

A device is subject to a series of shocks which cause damage and eventually failure will occur at the time of arrival of one of the shocks. In between the shocks, the device is partially repaired as the cumulative damage decreases as some Markov process. The device must be replaced upon failure at some cost but it also can be replaced before failure at a lower cost. We consider the general case where the failure rate need not be increasing and replacement can be made at any time. The form of the optimal replacement policy is found and fairly general conditions are given for which a control limit policy is optimal.
A non-parametric measure of spatial interaction in point patterns
Authors: Van Lieshout M. N. M. , Baddeley A. J.
Published: July 2016

The strength and range of interpoint interactions in a spatial point process can be quantified by the function J = (1 - G)/(1 - F), where G is the nearest-neighbour distance distribution function and F the empty space function of the process. J(r) is identically equal to 1 for a Poisson process; values of J(r) smaller or larger than 1 indicate clustering or regularity, respectively. We show that, for a very large class of point processes, J(r) is constant for distances r greater than the range of spatial interaction. Hence both the range and type of interpoint interaction may be inferred from J without parametric model assumptions. We evaluate J(r) explicitly for a variety of point processes. The J function of the superposition of independent point processes is a weighted mean of the J functions of the individual processes.
Convex polytopes and Gaussian covariances
Authors: Vitale R. A.
Published: July 2016

Siegel (1993) presented a covariance identity involving normal variables that seems to flout notions of dependence. We show that it has an explanation from an unexpected quarter: convex geometry and the centroid known as the Steiner point. In the same geometric spirit, we introduce another identity for Gaussian covariances based on an Euler identity for the Steiner point.
From Sir Frank Whittle to the year 2000 — what is new in propulsion?
Authors: Calmon J.
Published: July 2016

It is with great admiration and much humility that I am able to give this talk in front of Sir Frank Whittle, universally recognised as the genuine pioneer of turbojet propulsion in the formula that made a success of aviation.

As a matter of fact, the patent request filed by Sir Frank Whittle in 1930 (Fig. 1) comprised all the components of today’s turbojets: multi-stage axial compressor followed by a centrifugal compressor, combustion chamber, turbine coupled direct to the compressor and propulsion nozzle.

In April 1937, with the assistance of British Thomson Houston, Sir Frank Whittle ran his first turbojet on the bench at a thrust of 200 daN (Fig. 2). The year after saw the beginning of the Whittle Wl turbojet tests at a thrust of 380 daN. This engine was to receive consecration by a first flight in May 1941 in a Gloster E28/39 specially built for the purpose. Subsequently, this aircraft was fitted with a 650 daN version incorporating an air cooled turbine.
A numerical model for analysis of thin wings in inviscid incompressible flow
Authors: Singh B. K. , Basu B. C.
Published: July 2016

A planar vortex sheet model for analysis of thin wings in inviscid incompressible flow is presented. In this model a network of spanwise quadratically varying semi-infinite doublet sheets is introduced which produces a continuous trailing vortex wake. The present method has been applied to wings fitted with partial span trailing edge flaps after appropriate modification to account for the flap juncture. Also, the problem of wings in sideslip is attempted by incorporating the zero load condition at the down stream wing tip. The comparison of results shows that the proposed model retains the simplicity of the vortex lattice model to a large extent while overcoming the limitations of the standard vortex lattice model regarding lattice arrangement and number.
On the prospects for increasing dynamic lift
Authors: Mabey D. G.
Published: July 2016

A review is given of some recent research, mainly at low speeds, into the development of dynamic lift. Sudden movement of aerodynamic surfaces can generate dynamic lift due to the transient development of separated flow. These dynamic effects are large and well established for aerofoils. They are considered likely to be small for highly swept wings and negligible for slender wings, but there is little experimental evidence to support this inference. The dynamic lift might be increased if conventional sinusoidal motions can be replaced by appropriate periodic saw-tooth motions.

The control of large-scale flow separations by rapid movements of aerodynamic surfaces requires further investigation to resolve some of the controversial issues raised in the review.
Wind tunnel interference on unsteady two-dimensional aerofoil motions in low speed flows
Authors: Cheung C. W. , Hancock G. J.
Published: July 2016

The aerodynamic characteristics of two-dimensional transient aerofoil motions in low-speed flows in a wind tunnel with either closed wall or open (jet) walls, including the effect of a downstream closed wall diffuser, have been investigated. The mathematical formulation for the aerofoil and its unsteady wake is based on linear theory and is solved by a piecewise linear vorticity method; the wall boundaries are represented by distributions of sources. Numerical calculations have been made for various values of tunnel height to chord ratio.

Interference effects on the rate of build up of lift to a steady state following a step change in incidence can be large, especially for open jet tunnels.
The Effects of Axial Forces to Dynamic Load Factors of the Beam Subjected to Transverse Impulsive Loads
Authors: Suzuki Shin-Ichi
Published: July 2016

The variations of dynamic load factors of a beam subjected to axial forces are investigated when transverse impulsive loads are applied. The relationships between constant axial forces P and dynamic load factors are obtained under various end conditions. Dynamic load factors are very different from 2.

Because it is difficult to obtain an exact solution when P is a function of ξ (co-ordinate of axial direction), analyses are carried out by the energy method, where P is assumed to be in the form of (1–ξm).
The Operator's View
Authors: Redrup D. F.
Published: July 2016

The Airline Pilot has little to do with Flight Testing for Certification, in fact, apart from a few specialist pilots in the airlines the average airline pilot takes no part in the Flight Test Programme.

Once an aircraft has been certificated, however, the airline pilot spends more time on the Flight Deck and has longer to experience the shortcomings of the Certification Programme than anyone else. He is then the Consumer, the man who spends hours with an expensive piece of machinery strapped to him and who suffers over a long period of time any cockpit design defects. For that reason a large part of this paper will be devoted to, I hope, useful criticism of Flight Deck Layouts as they affect the operating crew member.
Part 2. Possible Solutions to some of the Problems
Authors: Caplan H.
Published: July 2016

Hugh Gordon-Burge has stated with clarity and force two of the salient problems in air safety work—that of obtaining information on accidents and incidents and that of disseminating the useful results after investigation and analysis.

He has also asked a number of pertinent questions to which I will try to provide some answers. As a basis for further discussion I also offer some tentative solutions to certain of the problems he has identified.

The views expressed are entirely personal.
A Note on the Reattachment of Two-Dimensional Compressible Jets to Planes
Authors: Begg R. D.
Published: July 2016

The rapid growth of interest in fluid logic and control elements has refocused attention on the reattachment of two-dimensional jets to plane surfaces. Of particular interest is the size of the low-pressure bubble enclosed between the jet and the adjacent inclined plane, and the effect on this of fluid velocity and compressibility. Several full studies have been made of such flows, notably by Bourque and Newman, Sawyer and Olson, and the basic characteristics have been well established. Agreement has been reached that bubble length is independent of jet Reynolds number (above 104), but doubts remain as to the best method of measuring the bubble length and also as to the effect of compressibility on this measurement. In order to clear up some of these points for an investigation of compressible flow through control valves, some experimental tests have been carried out on the reattachment of air jets to a plane.
Constant Acceleration of an Undamped Simple Vibrator Through Resonance
Authors: Fearn R. L. , Millsaps K.
Published: July 2016

For a simple undamped vibrator driven by a force whose frequency varies linearly with time, simple algebraic expressions are derived which give values for the maximum amplitude performed by the vibrator and for the frequency of the driving force where the maximum displacement occurs. Driving forces of both increasing and decreasing frequencies are considered.
Present Trends in Research Towards All-Weather Landing for Civil Aircraft
Authors: Baxter J. R.
Published: July 2016

Following a brief description of the basic radio aids and the terminology used, the paper discusses in some detail the differences between the original British and American approaches to all-weather landing; the different types of equipment resulting from these two approaches are broadly described. The mixing of ideas which occurred at the IATA Conference at Lucerne in 1963 and the more recent tendency towards a blending of British and American ideas are then discussed, and some predictions are made as to the form of the ultimate all-weather landing system. Certain Australian contributions to display research and the simulation of low visibility in flight are mentioned in context.
A Note on the Estimation of Average Pressures from Instantaneous Velocities in Unsteady Flow
Authors: Wood C. J.
Published: July 2016

In a recent paper, the author described some experiments in which the average base pressure on a two-dimensional bluff body was estimated from a random sample of instantaneous velocity measurements taken in the irrotational flow outside the separating boundary layers at the trailing edge. Although the oncoming stream was steady, the flow near the model was subject to a periodic disturbance emanating from the wake vortex street. An experimental check showed that the pressure estimates obtained by using the steady Bernouilli equation were reasonably accurate. This note points out that the method of data reduction used in ref. 1 is not an approximation; it is exact.
The Coming of Multiple-Access Computers
Authors: Wilkes M. V.
Published: July 2016

When digital computers first became available many of us expected that they would have an early and significant impact on engineering design. This did not happen, and the reasons why it did not are worth examining. For one thing, the early computers were not nearly large enough; engineers do not build things out of spheres and parallelograms as mathematicians do, and quite a lot of storage space is needed to describe a typical problem in engineering design. Unfortunately, the big computers when they came were so expensive that it was not considered economic to allow users to handle them personally, and batch-processing techniques were introduced. The result was to create a barrier between the computer and the design engineer, and to make it impossible for him to get results of any kind without a delay amounting to a few hours at the very best, and often to much more. Emphasis in fact, was put on the efficiency with which the central processor of the computer was used and no regard at all was paid to the efficiency with which the users—in this case programmers and design engineers—worked. We are on the threshold of a development which, there is every reason to hope, will change the situation radically.
Improvements in Management Control of Complex Projects
Authors: Rowley D.
Published: July 2016

According to the Plowden report, the American worker has weekly earnings of 2 to 2 times those of the British worker. The report also stated that, for the same production run (of 100 aircraft), the average cost in the USA would be between 105 and 115 per cent of the British cost for the same aircraft. This means that the number of man-hours expended in Britain is of the order of 2 to 2 times the number of man-hours taken in the USA for the same job. Or, it means that, if we could make an aircraft in Britain for the same man-hours as in the USA, it could sell at only 40 to 50 per cent of the American equivalent. But bear in mind that the man-hours I refer to are for all employees, not just those usually charged direct.
Measurements of Entrainment by a Free Rotating Disc
Authors: Case P.
Published: July 2016

Measurements are presented of the amount of air which flows axially towards the surface of a disc rotating at various speeds when the nature of flow is turbulent.

The method used is similar to that of Ricou and Spalding for the case of the axisymmetrical turbulent jet. The area to one side of the disc is surrounded by a chamber, leaving a small gap between the chamber and the disc. Air is injected into this via a porous baffle until the pressure in the chamber is uniform and atmospheric, a condition which is taken to signify that the “entrainment appetite” of the disc is satisfied.

Existing theories predict the results obtained well at high disc Reynolds numbers, but give greater entrainment rates than experiment at low disc Reynolds numbers. More precise measurements are needed to substantiate these conclusions: in particular the use of a hot-wire anemometer seems essential.
A Low-Turbulence Wind Tunnel Driven by an Aerofoil-Type Centrifugal Blower
Authors: Bradshaw P.
Published: July 2016

In recent years, manufacturers of centrifugal blowers for ventilation systems have abandoned the traditional arrangement of radial vanes shown in Fig. 1(a) for the “backward-aerofoil” arrangement shown in Fig. 1(b), which is the same as a conventional centrifugal water pump. Unlike the older type, the aerofoil-type blower does not depend on “centrifugal force” to produce a pressure rise despite the misleading accounts given in some hydraulics textbooks (the circumferential component of the air velocity is zero at entry and small at exit) although it does depend on the increase in blade peripheral velocity from the entry to the exit (which explains the curious blade arrangement).
An Analysis of the Randomness of Air Accidents
Authors: Miller Ronald E. , Quandt Richard E.
Published: July 2016

In this paper we examine the hypothesis that aeroplane accidents are grouped, ie that individual accidents are not randomly spaced in time. While it has not been possible to find any explicit statements of the non-randomness hypothesis, it seems to be a widely-held belief. In its least precise form, the belief is that as soon as there is one aeroplane accident, there will be “several more within a relatively short period of time”. Clearly one does not expect equal or even near-equal spacing between aircraft accidents; the interesting question is what amount of bunching leads to the rejection of randomness as an adequate description of the underlying distribution. And if non-randomness is encountered in practice, how is it explained or interpreted?
On the Use of the Preston Tube in Concentric Annuli
Authors: Quarmby Alan
Published: July 2016

Experimental results are presented of the measurement of skin friction in fully developed turbulent flow in concentric annuli using Preston tubes situated on the inner and outer annular surfaces. Both Preston's calibration and Patel's calibration were used to evaluate the results. It was found that the latter gave excellent results. Several radius ratios were investigated with a reasonable range of the annulus Reynolds number. The good agreement was not affected by radius ratio or smallness of core tube within the range of these parameters investigated here.