bluuebunny/crossref_metadata_2025 huggingface dataset:
H6 Influenza Viruses Pose a Potential Threat to Human Health
Authors: Wang Guojun , Deng Guohua , Shi Jianzhong , Luo Weiyu , Zhang Guoquan , Zhang Qianyi , Liu Liling , Jiang Yongping , Li Chengjun , Sriwilaijaroen Nongluk , Hiramatsu Hiroaki , Suzuki Yasuo , Kawaoka Yoshihiro , Chen Hualan
Published: February 2014

Influenza viruses of the H6 subtype have been isolated from wild and domestic aquatic and terrestrial avian species throughout the world since their first detection in a turkey in Massachusetts in 1965. Since 1997, H6 viruses with different neuraminidase (NA) subtypes have been detected frequently in the live poultry markets of southern China. Although sequence information has been gathered over the last few years, the H6 viruses have not been fully biologically characterized. To investigate the potential risk posed by H6 viruses to humans, here we assessed the receptor-binding preference, replication, and transmissibility in mammals of a series of H6 viruses isolated from live poultry markets in southern China from 2008 to 2011. Among the 257 H6 strains tested, 87 viruses recognized the human type receptor. Genome sequence analysis of 38 representative H6 viruses revealed 30 different genotypes, indicating that these viruses are actively circulating and reassorting in nature. Thirty-seven of 38 viruses tested in mice replicated efficiently in the lungs and some caused mild disease; none, however, were lethal. We also tested the direct contact transmission of 10 H6 viruses in guinea pigs and found that 5 viruses did not transmit to the contact animals, 3 viruses transmitted to one of the three contact animals, and 2 viruses transmitted to all three contact animals. Our study demonstrates that the H6 avian influenza viruses pose a clear threat to human health and emphasizes the need for continued surveillance and evaluation of the H6 influenza viruses circulating in nature.

IMPORTANCE
Avian influenza viruses continue to present a challenge to human health. Research and pandemic preparedness have largely focused on the H5 and H7 subtype influenza viruses in recent years. Influenza viruses of the H6 subtype have been isolated from wild and domestic aquatic and terrestrial avian species throughout the world since their first detection in the United States in 1965. Since 1997, H6 viruses have been detected frequently in the live poultry markets of southern China; however, the biological characterization of these viruses is very limited. Here, we assessed the receptor-binding preference, replication, and transmissibility in mammals of a series of H6 viruses isolated from live poultry markets in southern China and found that 34% of the viruses are able to bind human type receptors and that some of them are able to transmit efficiently to contact animals. Our study demonstrates that the H6 viruses pose a clear threat to human health.
Mechanism of Action and Capsid-Stabilizing Properties of VHHs with an
In Vitro
Antipolioviral Activity
Authors: Schotte Lise , Strauss Mike , Thys Bert , Halewyck Hadewych , Filman David J. , Bostina Mihnea , Hogle James M. , Rombaut Bart
Published: February 2014

Previously, we reported on the
in vitro
antiviral activity of single-domain antibody fragments (VHHs) directed against poliovirus type 1. Five VHHs were found to neutralize poliovirus type 1 in an
in vitro
setting and showed 50% effective concentrations (EC
50
s) in the nanomolar range. In the present study, we further investigated the mechanism of action of these VHHs. All five VHHs interfere at multiple levels of the viral replication cycle, as they interfere both with attachment of the virus to cells and with viral uncoating. The latter effect is consistent with their ability to stabilize the poliovirus capsid, as observed in a ThermoFluor thermal shift assay, in which the virus is gradually heated and the temperature causing 50% of the RNA to be released from the capsid is determined, either in the presence or in the absence of the VHHs. The VHH-capsid interactions were also seen to induce aggregation of the virus-VHH complexes. However, this observation cannot yet be linked to their mechanism of action. Cryo-electron microscopy (cryo-EM) reconstructions of two VHHs in complex with poliovirus type 1 show no conformational changes of the capsid to explain this aggregation. On the other hand, these reconstructions do show that the binding sites of VHHs PVSP6A and PVSP29F overlap the binding site for the poliovirus receptor (CD155/PVR) and span interfaces that are altered during receptor-induced conformational changes associated with cell entry. This may explain the interference at the level of cell attachment of the virus as well as their effect on uncoating.

IMPORTANCE
The study describes the mechanism of neutralization and the capsid-stabilizing activity of five single-domain antibody fragments (VHHs) that have an
in vitro
neutralizing activity against poliovirus type 1. The results show that the VHHs interfere at multiple levels of the viral replication cycle (cell attachment and viral uncoating). These mechanisms are possibly shared by some conventional antibodies and may therefore provide some insight into the natural immune responses. Since the binding sites of two VHHs studied by cryo-EM are very similar to that of the receptor, the VHHs can be used as probes to study the authentic virus-cell interaction. The structures and conclusions in this study are original and raise interesting findings regarding virus-receptor interactions and the order of key events early in infection.
Relative Roles of GM1 Ganglioside,
N
-Acylneuraminic Acids, and α2β1 Integrin in Mediating Rotavirus Infection
Authors: Fleming Fiona E. , Böhm Raphael , Dang Vi T. , Holloway Gavan , Haselhorst Thomas , Madge Paul D. , Deveryshetty Jaigeeth , Yu Xing , Blanchard Helen , von Itzstein Mark , Coulson Barbara S.
Published: February 2014

N
-acetyl- and
N
-glycolylneuraminic acids (Sia) and α2β1 integrin are frequently used by rotaviruses as cellular receptors through recognition by virion spike protein VP4. The VP4 subunit VP8*, derived from Wa rotavirus, binds the internal
N
-acetylneuraminic acid on ganglioside GM1. Wa infection is increased by enhanced internal Sia access following terminal Sia removal from main glycan chains with sialidase. The GM1 ligand cholera toxin B (CTB) reduces Wa infectivity. Here, we found sialidase treatment increased cellular GM1 availability and the infectivity of several other human (including RV-3) and animal rotaviruses, typically rendering them susceptible to methyl α-
d
-
N
-acetylneuraminide treatment, but did not alter α2β1 usage. CTB reduced the infectivity of these viruses. Aceramido-GM1 inhibited Wa and RV-3 infectivity in untreated and sialidase-treated cells, and GM1 supplementation increased their infectivity, demonstrating the importance of GM1 for infection. Wa recognition of α2β1 and internal Sia were at least partially independent. Rotavirus usage of GM1 was mapped to VP4 using virus reassortants, and RV-3 VP8* bound aceramido-GM1 by saturation transfer difference nuclear magnetic resonance (STD NMR). Most rotaviruses recognizing terminal Sia did not use GM1, including RRV. RRV VP8* interacted minimally with aceramido-GM1 by STD NMR. Unusually, TFR-41 rotavirus infectivity depended upon terminal Sia and GM1. Competition of CTB, Sia, and/or aceramido-GM1 with cell binding by VP8* from representative rotaviruses showed that rotavirus Sia and GM1 preferences resulted from VP8*-cell binding. Our major finding is that infection by human rotaviruses of commonly occurring VP4 serotypes involves VP8* binding to cell surface GM1 glycan, typically including the internal
N
-acetylneuraminic acid.

IMPORTANCE
Rotaviruses, the major cause of severe infantile gastroenteritis, recognize cell surface receptors through virus spike protein VP4. Several animal rotaviruses are known to bind sialic acids at the termini of main carbohydrate chains. Conversely, only a single human rotavirus is known to bind sialic acid. Interestingly, VP4 of this rotavirus bound to sialic acid that forms a branch on the main carbohydrate chain of the GM1 ganglioside. Here, we use several techniques to demonstrate that other human rotaviruses exhibit similar GM1 usage properties. Furthermore, binding by VP4 to cell surface GM1, involving branched sialic acid recognition, is shown to facilitate infection. In contrast, most animal rotaviruses that bind terminal sialic acids did not utilize GM1 for VP4 cell binding or infection. These studies support a significant role for GM1 in mediating host cell invasion by human rotaviruses.
Vocal cord paralysis associated with Ramsay Hunt syndrome: looking back 50 years
Authors: Rasmussen Eva Rye , Mey Kristianna
Published: February 2014

Ramsay Hunt syndrome is defined by herpes zoster oticus and peripheral facial nerve palsy which is often associated with otalgia. The syndrome is, in rare cases, associated with other cranial nerve paralyses including the vagal nerve causing unilateral vocal cord paralysis. Vocal cord paralysis is more often seen as a symptom of various other diseases, that is, malignant tumours, neurodegenerative illness, cerebrovascular assaults, inflammatory processes or as a result of intubation or surgical procedures. The symptoms of unilateral vocal cord paralysis are mainly hoarseness, dyspnoea and dysphagia. We present a case of Ramsay Hunt syndrome combined with unilateral hearing loss and left vocal cord paralysis. The patient underwent MRI, CT and a lumbar puncture causing anxiety in the patient and delaying the initiation of antiviral and anti-inflammatory treatment, which is only efficient when initiated within 72 h. We hope to raise the awareness of this disease.
CD8 transverse myelitis in a patient with HIV-1 infection
Authors: Moulignier Antoine , Lescure François-Xavier , Savatovsky Julien , Campa Pauline
Published: February 2014

CD8 T-cell neurological complications are a new HIV-driven condition caused by an unusually intense inflammatory reaction with influx of CD8 lymphocytes in the nervous system. Encephalitis and neuropathies have been described. We report the first case of spinal cord involvement. A 52-year-old African woman with HIV infection not profoundly immunosuppressed, and with a low plasmatic viral replication, without antiretroviral therapy, presented with transverse myelitis. Spinal MRI revealed inflammatory intraspinal gadolinium-enhanced lesions. Exhaustive workup was negative and brain biopsy revealed a significant inflammatory reaction with abundant CD8 T cells. Intravenous pulse methylprednisolone treatment led to rapid, disease-free recovery. CD8 T cells transverse myelitis in patients with HIV infection receiving antiretroviral therapy is a clinical entity that should be added to the list of HIV complications.
Food-dependent exercise-induced anaphylaxis with negative allergy testing
Authors: Kleiman Jacob , Ben-Shoshan Moshe
Published: February 2014

Food-dependent exercise-induced anaphylaxis (FDEIA) is a disorder where exercise following allergen ingestion triggers anaphylaxis although exercise and allergen exposure are independently tolerated. The diagnosis of FDEIA is based on a characteristic clinical history. The culprit allergen is usually confirmed through the use of skin prick testing (SPT) serum-specific IgE levels and a food–exercise challenge. We present a case of FDEIA suggested by clinical history and open food–exercise challenge with negative specific IgE levels and SPT that highlights the challenges involved in diagnosing and managing this rare disorder.
Polyarteritis nodosa presenting as profuse gastrointestinal bleeding
Authors: Vaidya Gaurang Nandkishor , Khorasani-Zadeh Arman , John Savio
Published: February 2014

A 70-year-old man presented with acute onset of profuse bleeding per rectum. An urgent colonoscopy showed blood throughout the colon and distal ileum but failed to localise the source. Subsequent visceral arteriography revealed pseudoaneurysms of the branches of the superior mesenteric artery and left gastric artery. The bleeding stopped spontaneously and the aetiology of the bleeding was later found out to be secondary to polyarteritis nodosa (PAN). The presence of profuse gastrointestinal bleeding as the sole manifestation at presentation in PAN is under-reported. Early diagnosis of PAN in patients with haemodynamically significant bleeding is necessary as prompt initiation of immunosuppressive therapy helps prevent relapses. With this case report, we highlight one of the unusual presentations of PAN and the favourable response to immunosuppression with pulsed dose steroids.
Effect of a 6-month vegan low-carbohydrate (‘Eco-Atkins’) diet on cardiovascular risk factors and body weight in hyperlipidaemic adults: a randomised controlled trial
Authors: Jenkins David J A , Wong Julia M W , Kendall Cyril W C , Esfahani Amin , Ng Vivian W Y , Leong Tracy C K , Faulkner Dorothea A , Vidgen Ed , Paul Gregory , Mukherjea Ratna , Krul Elaine S , Singer William
Published: February 2014

Objective

Low-carbohydrate diets may be useful for weight loss. Diets high in vegetable proteins and oils may reduce the risk of coronary heart disease. The main objective was to determine the longer term effect of a diet that was both low-carbohydrate and plant-based on weight loss and low-density lipoprotein cholesterol (LDL-C).

Design, setting, participants

A parallel design study of 39 overweight hyperlipidaemic men and postmenopausal women conducted at a Canadian university-affiliated hospital nutrition research centre from April 2005 to November 2006.

Intervention

Participants were advised to consume either a low-carbohydrate vegan diet or a high-carbohydrate lacto-ovo vegetarian diet for 6 months after completing 1-month metabolic (all foods provided) versions of these diets. The prescribed macronutrient intakes for the low-carbohydrate and high-carbohydrate diets were: 26% and 58% of energy from carbohydrate, 31% and 16% from protein and 43% and 25% from fat, respectively.

Primary outcome

Change in body weight.

Results

23 participants (50% test, 68% control) completed the 6-month ad libitum study. The approximate 4 kg weight loss on the metabolic study was increased to −6.9 kg on low-carbohydrate and −5.8 kg on high-carbohydrate 6-month ad libitum treatments (treatment difference (95% CI) −1.1 kg (−2.1 to 0.0), p=0.047). The relative LDL-C and triglyceride reductions were also greater on the low-carbohydrate treatment (treatment difference (95% CI) −0.49 mmol/L (−0.70 to −0.28), p<0.001 and −0.34 mmol/L (−0.57 to −0.11), p=0.005, respectively), as were the total cholesterol:HDL-C and apolipoprotein B:A1 ratios (−0.57 (−0.83, −0.32), p<0.001 and −0.05 (−0.09, −0.02), p=0.003, respectively).

Conclusions

A self-selected low-carbohydrate vegan diet, containing increased protein and fat from gluten and soy products, nuts and vegetable oils, had lipid lowering advantages over a high-carbohydrate, low-fat weight loss diet, thus improving heart disease risk factors.

Trial Registration

clinicaltrials.gov (http://www.clinicaltrials.gov/), #NCT00256516.
Guidelines: is bigger better? A review of SIGN guidelines
Authors: Baird A Gordon , Lawrence James R
Published: February 2014

Objectives

To quantify and analyse the quality of evidence that is presented in national guidelines.

Setting

Levels of evidence used in all the current valid recommendations in the Scottish Intercollegiate Guideline Network (SIGN) guidelines were reviewed and statistically analysed.

Outcome measures

The proportion of level D evidence used in each guideline and a statistical analysis.

Method

Data were collected from published guidelines available online to the public. SIGN methodology entails a professional group selected by a national organisation to develop each of these guidelines. Statistical analysis of the relationship between the number of guideline recommendations and the quality of evidence used in its recommendations was performed.

Result

The proportion of level D evidence increases with the number of recommendations made. This correlation is significant with Kendall's τ=0.22 (approximate 95% CI 0.008 to 0.45), p = 0.04; and Spearman ρ=0.22 (approximate 95% CI 0.02 to 0.57), p=0.04.

Conclusions

Practice guidelines should be brief and based on scientific evidence. Paradoxically the longest guidelines have the highest proportion of recommendations based on the lowest level of evidence. Guideline developers should be more aware of the need for brevity and a stricter application of evidence-based principles could achieve this. The findings support calls for a review of how evidence is used and presented in guidelines.
Additive influence of genetic predisposition and conventional risk factors in the incidence of coronary heart disease: a population-based study in Greece
Authors: Yiannakouris Nikos , Katsoulis Michail , Trichopoulou Antonia , Ordovas Jose M , Trichopoulos Dimitrios
Published: February 2014

Objectives

An additive genetic risk score (GRS) for coronary heart disease (CHD) has previously been associated with incident CHD in the population-based Greek European Prospective Investigation into Cancer and nutrition (EPIC) cohort. In this study, we explore GRS-‘environment’ joint actions on CHD for several conventional cardiovascular risk factors (ConvRFs), including smoking, hypertension, type-2 diabetes mellitus (T2DM), body mass index (BMI), physical activity and adherence to the Mediterranean diet.

Design

A case–control study.

Setting

The general Greek population of the EPIC study.

Participants and outcome measures

477 patients with medically confirmed incident CHD and 1271 controls participated in this study. We estimated the ORs for CHD by dividing participants at higher or lower GRS and, alternatively, at higher or lower ConvRF, and calculated the relative excess risk due to interaction (RERI) as a measure of deviation from additivity.

Results

The joint presence of higher GRS and higher risk ConvRF was in all instances associated with an increased risk of CHD, compared with the joint presence of lower GRS and lower risk ConvRF. The OR (95% CI) was 1.7 (1.2 to 2.4) for smoking, 2.7 (1.9 to 3.8) for hypertension, 4.1 (2.8 to 6.1) for T2DM, 1.9 (1.4 to 2.5) for lower physical activity, 2.0 (1.3 to 3.2) for high BMI and 1.5 (1.1 to 2.1) for poor adherence to the Mediterranean diet. In all instances, RERI values were fairly small and not statistically significant, suggesting that the GRS and the ConvRFs do not have effects beyond additivity.

Conclusions

Genetic predisposition to CHD, operationalised through a multilocus GRS, and ConvRFs have essentially additive effects on CHD risk.
Team-training in healthcare: a narrative synthesis of the literature
Authors: Weaver Sallie J , Dy Sydney M , Rosen Michael A
Published: February 2014

Background

Patients are safer and receive higher quality care when providers work as a highly effective team. Investment in optimising healthcare teamwork has swelled in the last 10 years. Consequently, evidence regarding the effectiveness for these interventions has also grown rapidly. We provide an updated review concerning the current state of team-training science and practice in acute care settings.

Methods

A PubMed search for review articles examining team-training interventions in acute care settings published between 2000 and 2012 was conducted. Following identification of relevant reviews with searches terminating in 2008 and 2010, PubMed and PSNet were searched for additional primary studies published in 2011 and 2012. Primary outcomes included patient outcomes and quality indices. Secondary outcomes included teamwork behaviours, knowledge and attitudes.

Results

Both simulation and classroom-based team-training interventions can improve teamwork processes (eg, communication, coordination and cooperation), and implementation has been associated with improvements in patient safety outcomes. Thirteen studies published between 2011 and 2012 reported statistically significant changes in teamwork behaviours, processes or emergent states and 10 reported significant improvement in clinical care processes or patient outcomes, including mortality and morbidity. Effects were reported across a range of clinical contexts. Larger effect sizes were reported for bundled team-training interventions that included tools and organisational changes to support sustainment and transfer of teamwork competencies into daily practice.

Conclusions

Overall, moderate-to-high-quality evidence suggests team-training can positively impact healthcare team processes and patient outcomes. Additionally, toolkits are available to support intervention development and implementation. Evidence suggests bundled team-training interventions and implementation strategies that embed effective teamwork as a foundation for other improvement efforts may offer greatest impact on patient outcomes.
Improving waiting time and operational clinic flow in a tertiary diabetes center
Authors: Ho Emily Tse Lin
Published: February 2014

The Singapore General Hospital Diabetes Centre (DBC) is a multidisciplinary specialist outpatient clinic which aims to provide an integrated one-stop service for diabetes. As with many tertiary academic centre clinics, DBC encounters an expanding patient load, greater patient expectations and increasingly complicated patients who require services from a multitude of health providers. Such rising demands amidst limited resources cause inefficiencies and long waiting times to consultation. This result in low patient satisfaction and an unpleasant clinic experience. A multidisciplinary team was formed to reduce the waiting time at DBC and improve communication and work processes of staff.

Addressing wait-times is complicated as multiple stakeholders and operational processes are involved and interlinked. By systematically breaking down processes and identifying problem areas, targeted changes were implemented. This included a revised model of appointment scheduling, a patient reminder system, more effective communication sheets and work reassignments.

The primary aim of this project was to improve the patient turn-around time (duration a patient spends at the centre for a visit). There was no documented improvement in turn-around time after project implementation ( 108.23 minutes versus 106.6 minutes) but other secondary aims were achieved. These included an increase in the percentage of patients seen by the doctor within 60 minutes from 80% to 84%, a reduction in wait-time for payment and reappointment at the cashier by 36.6% and a reduction in non-attendances of new cases to the clinic from 30.2% to 21.3%. Staff satisfaction and communication were greatly improved. To aid sustainability, personalized reports of individual doctor’s waiting times and workload were produced quarterly and tracked.

As this is a first step quality improvement project, efforts to track, examine and further improve turn-around times are on-going. Future initiatives are directed at time-efficient appointment scheduling between care providers for same day appointments, a reactive SMS system for reminders and reappointments and optimization of processes and manpower allocation for clinics.
Unified hardening (UH) model for overconsolidated unsaturated soils
Authors: Yao Y.P. , Niu L. , Cui W.J.
Published: February 2014

Naturally deposited clays are often unsaturated and overconsolidated. Within the frameworks of the Barcelona Basic model (BBM) for normally consolidated unsaturated clays and the unified hardening (UH) model for overconsolidated saturated clays, a three-dimensional constitutive model for overconsolidated unsaturated clays is proposed in this paper. This model can be reduced to the original UH model for overconsolidated saturated clays when suction becomes zero and the BBM when the overconsolidated behaviour disappears. Compared with existing constitutive models for unsaturated clays, the influence of a high overconsolidation ratio (OCR) on wetting deformation can be adequately described. Also, many other characteristics of overconsolidated unsaturated clays can be modelled, including strain-hardening, softening, shear dilatancy, and stress path–dependence behaviour. Compared with the BBM, the proposed model requires no additional material parameter. The validity of the UH model for overconsolidated unsaturated clays has been confirmed by data from two groups of wetting tests performed by the authors and previous triaxial tests in the literature.
Critical review of the CSA A14-07 design provisions for torsion in prestressed concrete poles
Authors: Kuebler Michael , Polak Maria Anna
Published: February 2014

This paper focuses on the effect of the transverse reinforcement in concrete poles and its influence on torsional strength in an effort to simplify the governing Canadian prestressed concrete pole code (CSA A14-07). The rationale behind the CSA code values for amount, spacing, and direction of the transverse reinforcement is not apparent. A testing program consisting of 14 concrete pole specimens were produced to investigate the torsional response. The specimens were divided into two groups with different tip diameters. Within each group the spacing and direction of the wound helical transverse reinforcement varied. Experimental cracking torque values were compared with calculated theoretical cracking torques from ACI 318, Eurocode 2, and various journal articles. The theoretical predictions were generally unconservative. Post-cracking behaviour was modelled using the Compression Field Theory (CFT) and Softened Truss Model (STM) for torsion. It was found that the CFT predicts the post-cracking response with reasonable accuracy. The failure mode in pure torsion is brittle and sudden, and the transverse reinforcement provides no post-cracking ductility. The primary function of the transverse reinforcement is to minimize the longitudinal precracking due to prestressing transfer forces. CSA A14 transverse reinforcement spacing requirements were compared against code minimum spacing requirements and a strut and tie model of the prestressing force transfer zone. Based on the strut and tie model of the transfer zone it was concluded that the CSA A14 helical reinforcement spacing values were insufficient to resist the transfer forces. New helical reinforcement spacing values were recommended to simplify the current CSA A14 code requirements. In addition concrete mix designs, prestressing levels, and wall thicknesses all have a large impact on torsional capacity and therefore quality assurance of these factors should be emphasized in CSA A14.
Schwinger’s approach to Einstein’s gravity and beyond
Authors: Milton K.A.
Published: February 2014

J. Schwinger (1918–1994), founder of renormalized quantum electrodynamics, was arguably the leading theoretical physicist of the second half of the 20th century. Thus it is not surprising that he made contributions to gravity theory as well. His students made major impacts on the still uncompleted program of constructing a quantum theory of gravity. Schwinger himself had no doubt of the validity of general relativity, although he preferred a particle physics viewpoint based on gravitons and the associated fields, and not the geometrical picture of curved space–time. This article provides a brief summary of his contributions and attitudes toward the subject of gravity.
ECONOMIC PRODUCTION LOT SIZING MODEL WITH STOCHASTIC DEMAND
Authors: LEE SHINE-DER , LAN SHU-CHUAN , YANG CHIN-MING
Published: February 2014

We consider the extended economic production quantity (EPQ) problem when demand follows a Poisson process in a production system. A fixed lot sizing policy is implemented to minimize fluctuation of workload, and to smooth production planning and inventory control. The considered costs include setup cost, inventory carrying cost, and shortage cost when demand cannot be satisfied from stock. The main contributions of this paper are two folds. We develop and analyze the extended EPQ model. Under some mild conditions, the expected cost per unit time can be shown to be convex. Via computational experiments, we demonstrate that, in comparison with classical EPQ model, the average reduction of expected cost is significant when demand is random and the proposed model is used to determine lot sizing policy. Our computational tests have also illustrated the impact of various parameters on the expected cost model and the lot sizing policy.
Kaluza–Klein wormholes with the compactified fifth dimension
Authors: Dzhunushaliev Vladimir , Folomeev Vladimir
Published: February 2014

We consider wormhole solutions in five-dimensional Kaluza–Klein gravity in the presence of a massless ghost four-dimensional scalar field. The system possesses two types of topological nontriviality connected with the presence of the scalar field and of a magnetic charge. Mathematically, the presence of the charge appears in the fact that the S3 part of a spacetime metric is the Hopf bundle S3 →S2 with fiber S1. We show that the fifth dimension spanned on the sphere S1 is compactified in the sense that asymptotically, at large distances from the throat, the size of S1 is equal to some constant, the value of which can be chosen to lie, say, in the Planck region. Then, from the four-dimensional point of view, such a wormhole contains a radial magnetic (monopole) field, and an asymptotic four-dimensional observer sees a wormhole with the compactified fifth dimension.
HIGGS INFLATION IN f(Φ, R) THEORY
Authors: CHAKRAVARTY GIRISH KUMAR , MOHANTY SUBHENDRA , SINGH NAVEEN K.
Published: February 2014

We generalize the scalar-curvature coupling model ξΦ2R of Higgs inflation to ξΦaRb to study inflation. We compute the amplitude and spectral index of curvature perturbations generated during inflation and fix the parameters of the model by comparing these with the Planck + WP data. We find that if the scalar self-coupling λ is in the range 10-5–0.1, parameter a in the range 2.3–3.6 and b in the range 0.77–0.22 at the Planck scale, one can have a viable inflation model even for ξ ≃ 1. The tensor to scalar ratio r in this model is small and our model with scalar-curvature couplings is not ruled out by observational limits on r unlike the pure [Formula: see text] theory. By requiring the curvature coupling parameter to be of order unity, we have evaded the problem of unitarity violation in scalar-graviton scatterings which plague the ξΦ2R Higgs inflation models. We conclude that the Higgs field may still be a good candidate for being the inflaton in the early universe if one considers higher-dimensional curvature coupling.
EXTREMAL MYERS–PERRY BLACK HOLES COUPLED TO BORN–INFELD ELECTRODYNAMICS IN ODD DIMENSIONS
Authors: ALLAVERDIZADEH MASOUD , HENDI SEYED H. , LEMOS JOSÉ P. S. , SHEYKHI AHMAD
Published: February 2014

Employing higher-order perturbation theory, we find a new class of perturbative extremal rotating black hole solutions with Born–Infeld electric charge in odd D dimensional spacetime. The seed solution is an odd-dimensional extremal Myers–Perry black hole with equal angular momenta to which a perturbative, nonlinear, electric Born–Infeld field charge q is added maintaining the extremality condition. The perturbations are performed up to third-order. We also study some physical properties of these black holes. In particular, it is shown that the values of the gyromagnetic ratio of the black holes are modified by the perturbative parameter q and the Born–Infeld parameter β.
VALUE-AT-RISK COMPUTATIONS IN STOCHASTIC VOLATILITY MODELS USING SECOND-ORDER WEAK APPROXIMATION SCHEMES
Authors: LÜTKEBOHMERT EVA , MATCHIE LYDIENNE
Published: February 2014

We explore the class of second-order weak approximation schemes (cubature methods) for the numerical simulation of joint default probabilities in credit portfolios where the firm's asset value processes are assumed to follow the multivariate Heston stochastic volatility model. Correlation between firms' asset processes is reflected by the dependence on a common set of underlying risk factors. In particular, we consider the Ninomiya–Victoir algorithm and we study the application of this method for the computation of value-at-risk and expected shortfall. Numerical simulations for these quantities for some exogenous portfolios demonstrate the numerical efficiency of the method.
EVOLUTION OF COOPERATION IN THE SNOWDRIFT GAME WITH HETEROGENEOUS POPULATION
Authors: BARREIRA DA SILVA ROCHA ANDRÉ , LARUELLE ANNICK
Published: February 2014

Different from previous studies of tag-based cooperation, we assume that individuals fail to recognize their own tag. Due to such incomplete information, the action taken against the opponent cannot be based on similarity, although it is still motivated by the tag displayed by the opponent. We present stability conditions for the case when individuals play unconditional cooperation, unconditional defection or conditional cooperation. We then consider the removal of one or two strategies. Results show that conditional cooperators are the most resilient agents against extinction and that the removal of unconditional cooperators may lead to the extinction of unconditional defectors.
LOCAL UNITARY EQUIVALENT CLASSES OF SYMMETRIC N-QUBIT MIXED STATES
Authors: ASHOURISHEIKHI SAKINEH , SIRSI SWARNAMALA
Published: February 2014

Majorana representation (MR) of symmetric N-qubit pure states has been used successfully in entanglement classification. Generalization of this has been a long standing open problem due to the difficulties faced in the construction of a Majorana like geometric representation for symmetric mixed state. We have overcome this problem by developing a method of classifying local unitary (LU) equivalent classes of symmetric N-qubit mixed states based on the geometrical multiaxial representation (MAR) of the density matrix. In addition to the two parameters defined for the entanglement classification of the symmetric pure states based on MR, namely, diversity degree and degeneracy configuration, we show that another parameter called rank needs to be introduced for symmetric mixed state classification. Our scheme of classification is more general as it can be applied to both pure and mixed states. To bring out the similarities/differences between the MR and MAR, N-qubit GHZ state is taken up for a detailed study. We conclude that pure state classification based on MR is not a special case of our classification scheme based on MAR. We also give a recipe to identify the most general symmetric N-qubit pure separable states. The power of our method is demonstrated using several well-known examples of symmetric two-qubit pure and mixed states as well as three-qubit pure states. Classification of uniaxial, biaxial and triaxial symmetric two-qubit mixed states which can be produced in the laboratory is studied in detail.
CLOSED-FORM WORKING VOLUME COMPUTATION AND STRUCTURAL OPTIMIZATION OF REDUNDANT SERIAL ROBOT CHAINS DERIVED FROM ZONOTOPE THEORY
Authors: TONDU BERTRAND
Published: February 2014

Application of Jacobian determinant of a nonredundant serial chain robot is a powerful and elegant way to deduce a closed-form computation of its working volume and the structural robot optimization. This approach highlighted in the 80's seems to have been neglected since then. We discuss under which joint conditions it can be considered and we show the possibility to extend this approach to redundant serial chain robots by substituting nonsquared Jacobian minors for squared-Jacobian determinant, thanks to the powerful so-called cubical dissection theorem peculiar to the zonotope theory. Two examples are considered: a 4R anthropomorphic regional arm structure and a 3R planar human digit-like structure.
TORSION VIBRATION AND PARAMETRIC INSTABILITY ANALYSIS OF A SPUR GEAR SYSTEM WITH TIME-VARYING AND SQUARE NONLINEARITIES
Authors: ZHANG WEI , DING QIAN
Published: February 2014

This paper investigates the dynamics of a spur gear system with time-varying and square nonlinearities, by both analytical method and numerical simulation. First, the equations of motion of a 2 degree-of-freedom system are established and the harmonic balance method is used to analyze the stability and the steady-state response of the system under the main resonant condition. Then the perturbation method is used to analyze the parameter instability under the main, subharmonic and nonresonance conditions. Finally, the interactions between the main and subharmonic resonant amplitudes and the nonlinearity and the contact ratio are analyzed. The results reveal that the system response contains various frequency components, such as meshing frequency and its higher harmonic terms due to the nonlinearity and the time-varying stiffness. The existence of the time-varying meshing stiffness can also result in the subharmonic resonance, and even chaos through period-doubling bifurcations as the input torque increases.
AN IMPROVED GENETIC ALGORITHM AND ITS APPLICATION TO CRACK EXAMINATION
Authors: GAO RUIPENG , SHANG CHUNYANG , ZHUANG JIAN , JIANG HANG
Published: February 2014

In this paper, a rail crack examination method based on an optimized complex evolutionary algorithm is proposed. The proposed approach has overcome the problems in which the fault diagnosis of wavelet packet decomposition is easily influenced by environmental factors, and the traditional genetic algorithm has a slow convergence speed and is prone to prematurity. In current method, to control the convergence performance, the diversity probability Pg is added in the update operation. According to the characteristics of rail crack fault signal, optimization function and cost function which consider the information in time and frequency domains are constructed and the information extraction is effectively realized. From field testing, the obtained results demonstrate that the present crack fault examination algorithm has higher accuracy rate, faster convergence rate and good stability. The present research work not only make up for the deficiency of traditional algorithm, but also provides a new examination method for wheel and rail noise fault diagnosis.
Analysis of powdered reference materials and known samples with a benchtop, field portable X-ray fluorescence (pXRF) spectrometer: evaluation of performance and potential applications for exploration lithogeochemistry
Authors: Piercey Stephen J. , Devine Mary C.
Published: February 2014

Powdered international reference materials and samples with previously obtained conventional geochemical data were analysed using a benchtop portable X-ray fluorescence (pXRF) spectrometer to test the abilities of pXRF in silicate rock lithogeochemistry. Results from international reference materials illustrate that pXRF can provide very precise data for many major, minor, and trace elements, generally with RSD values of <7.5 % and many <5 %, except at very low concentrations (i.e. approaching the limit of detection). Despite good precision, accuracy is highly variable and ranges from excellent to reasonable for many major and minor elements (±15–20 % relative difference, RD, for Al
2
O
3
, SiO
2
, K
2
O, CaO, Fe
2
O
3
, TiO
2
, and MnO±S), base metals (±20 % for Cu, Zn), the low field strength (LFSE) and high field strength elements (HFSE) (±15 % RD for Rb, Ba, Zr; ±20 % RD for Nb). Poor accuracy was obtained for MgO, P
2
O
5
, and the transition elements (V, Cr, Ni); Sr shows variable accuracy.

Comparison of pXRF results to independent samples with data from conventional analyses illustrates very poor correlation for MgO, P
2
O
5
, V, Cr, and Ni, suggesting they have poor accuracy by pXRF. Aluminum (Al
2
O
3
), SiO
2
, and Zn have r
2
values of
c
. 0.6–0.7 illustrating reasonable correlation, whereas most other elements (S, K
2
O, CaO, TiO
2
, MnO, Fe
2
O
3
, Co, Cu, Pb, Rb, Sr, Ba, Zr, Nb, U, As, and Mo) have very good to excellent correlation between pXRF data and conventional analysis (i.e. r
2
>0.80). In addition, many of the elements with r
2
>0.8 have slopes that are close to 1 or within 20 % of ideal, indicating that pXRF is replicating the results of conventional analyses and likely within ±20 % of what can be obtained by conventional methods. Down-hole profiles of pXRF data and element ratios replicate the geometry of the profiles from conventional analyses and illustrate the ability of the pXRF to discriminate rock type, alteration, and mineralization in unknown samples.

Portable XRF can provide fit-for-purpose data that is useful in discriminating lithogeochemical variations related to lithology, alteration, and mineralization. However, pXRF should be considered a preliminary screening tool for sample selection and not a substitute for conventional lithogeochemical methods (e.g. XRF, fusion ICP-ES and ICP-MS), particularly when important economic decisions are to be made using such data (e.g. NI-43-101 resource calculations).

Supplementary Material:

Collated data for repeat analyses of reference materials in Mining Plus (Table 1) and Soil 3 Beam (Table 2) modes. Tables 3-9 contain plots comparing results from pXRF to accepted values for various reference materials. All tables are available at at
www.geolsoc.org.uk/SUP18735
Discerning magmatic flow patterns in shallow-level basaltic dykes from the NE rift zone of Tenerife, Spain, using the Anisotropy of Magnetic Susceptibility (AMS) technique
Authors: Delcamp A. , Petronis M. S. , Troll V. R.
Published: February 2014

The anisotropy of magnetic susceptibility (AMS) technique is a rapid petrophysical method used to infer magma flow directions within dykes as well as other igneous intrusions. Samples for AMS study were collected from dykes along the upper part of the NE Rift Zone (NERZ) of Tenerife, Canary Islands, Spain. Of the analysed dykes, 28 have interpretable normal magnetic fabrics. These 28 dykes are therefore suitable to assess the magma flow direction using the imbrication of the magnetic foliation plane from paired dyke margins and/or the overall trend and plunge of the magnetic lineations. AMS fabrics show downwards and upwards flow that could be related to flank and summit eruptions. Overall, however, the direction and sense of magma flow does not follow a specific trend across the NERZ, suggesting that the dykes are supplied by local shallow-level reservoir(s) underneath the ridge or are responding to variations in the local stress field across the axis of the rift zone. The variability of the AMS fabrics suggests a rather complicated propagation mode of magma within the dykes of the NERZ, contrasting with the common assumption of uniform magma propagation within rift zones. Our data therefore support the notion that magma propagation beneath active volcanic systems is inherently more complex than simple subvertical flow from source to final emplacement level, which bears on volcanic hazards worldwide.
Quantifying bioturbation of a simulated ash fall event
Authors: Todd Joe A. , Austin William E. N. , Abbott Peter M.
Published: February 2014

Tephrochronology allows the establishment of ‘isochrons’ between marine, lacustrine, terrestrial and ice cores, typically based on the geochemical fingerprint of the tephra. The development of cryptotephrochronology has revealed a vast inventory of isochrons which hold the potential to improve stratigraphic correlation and identify systemic leads and lags in periods of rapid climate change. Unfortunately, bioturbation acts to blur these isochrons, reducing the temporal resolution in marine and lacustrine records. In order to better resolve these event horizons, we require a better understanding of bioturbative processes, and the depth and time over which they operate. To this end, an ash fall event was simulated on the intertidal zone of the Eden Estuary, Fife, Scotland and sediment cores were collected over 10 days. A novel approach to tephra quantification was developed, using the imaging software ImageJ. Our results showed limited bioturbation (mixed depth=18 mm), most likely owing to the fine grain size, low-energy environment and the resulting faunal composition of the sediments. These results imply a strong ecological control on bioturbation, and suggest that inferences may be made about palaeoenvironments from the observed bioturbation profiles.

supplementary material:

The ImageJ macro used in this study, as well as raw tephra concentration data and details of the method validation are available at
http://www.geolsoc.org.uk/SUP18725
.
Quaternary evolution of the Cordillera Frontal piedmont between
c.
33° and 34°S Mendoza, Argentina
Authors: Zárate M. A. , Mehl A. , Perucca L.
Published: February 2014

The piedmont of Cordillera Frontal between
c.
33° and 34°S (Mendoza, Argentina) is a highly populated area deeply modified by human activities, known as Valle de Uco. It is situated within the borderland region of the geological provinces of Cordillera Frontal and Cuyo basin. The landscape is dominantly composed of both erosional and depositional landforms made of fluvio-aeolian deposits fractured and folded by tectonic processes together with some landforms of volcanic origin. Alluvial fans, related to several aggradational cycles of Quaternary age, are the most remarkable geomorphological units. Several tectonic features are present giving rise to conspicuous morphological features. Some of the streams are structurally controlled by faults while several drainage anomalies that indicate active tectonic processes have been identified. The Late Quaternary alluvial sequences, dominantly comprising sandy and silty deposits of volcaniclastic composition and secondarily metamorphic rocks, represent the fine-grained sedimentary facies of the fluvial systems accumulated in a distal fan environment. The alluvial deposits have been incised by several episodes of erosion since Pleistocene time.
Volund Field: development of an Eocene sandstone injection complex, offshore Norway
Authors: Schwab Anne M. , Jameson Eric W. , Townsley Ann
Published: February 2014

The Volund Field lies in the Norwegian sector of the North Sea (Quad 24/9). This field produces from a ‘classic’ large-scale sandstone injection complex located in Lower Eocene strata. The sandstone reservoir has been injected into the lower permeability surrounding mudstones of the Sele and Balder formations and Hordaland Group to create an ‘intrusive trap’. The Volund Field consists of a deeper central unit of stacked sandstone sills, surrounded by shallower, steeper-dipping injected sandstone dykes, which make excellent reservoirs with consistently high porosity and permeability. Many of the steeply-dipping injected dykes appear to have excellent connectivity from the water leg through the oil leg and into the gas cap. The complex was identified on seismic data that exhibit a Class 3 amplitude versus offset (AVO) signature on the far-offset stack reflection seismic volume. The seismic data have been used to successfully locate horizontal production wells. Volund seismic geobodies have been extracted and incorporated into the reservoir geomodel to determine the geometry of the injectite features and to populate sands within the injection complex. Volund Field (estimated mean gross resource of 54 mmboe (million barrels oil equivalent)) is producing oil from four horizontal branches (end December 2012), with one water injector well, and has a common oil–water contact and gas–oil contact.