bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo
Pharmacodynamic Target Investigation of Two Bacterial Topoisomerase Inhibitors, ACT-387042 and ACT-292706, in the Neutropenic Murine Thigh Model against Streptococcus pneumoniae and Staphylococcus aureus
Authors: Lepak A. J. , Seiler P. , Surivet J. P. , Ritz D. , Kohl C. , Andes D. R.
Published: April 2016

ACT-387042 and ACT-292706 are two novel bacterial topoisomerase inhibitors with broad-spectrum activity against Gram-positive and -negative bacteria, including methicillin-resistant
Staphylococcus aureus
and penicillin- and fluoroquinolone-resistant
Streptococcus pneumoniae
. We used the neutropenic murine thigh infection model to characterize the pharmacokinetics (PK)/pharmacodynamics (PD) of these investigational compounds against a group of 10
S. aureus
and
S. pneumoniae
isolates with phenotypic resistance to beta-lactams and fluoroquinolones. The
in vitro
activities of the two compounds were very similar (MIC range, 0.03 to 0.125 mg/liter). Plasma pharmacokinetics were determined for each compound by using four escalating doses administered by the subcutaneous route. In treatment studies, mice had 10
7.4
to 10
8
CFU/thigh at the start of therapy with ACT-387042 and 10
6.7
to 10
8.3
CFU/thigh at the start of therapy with ACT-292706. A dose-response relationship was observed with all isolates over the dose range. Maximal kill approached 3 to 4 log
10
CFU/thigh compared to the burden at the start of therapy for the highest doses examined. There was a strong relationship between the PK/PD index AUC/MIC ratio (area under the concentration-time curve over 24 h in the steady state divided by the MIC) and therapeutic efficacy in the model (
R
2
, 0.63 to 0.82). The 24-h free-drug AUC/MIC ratios associated with net stasis for ACT-387042 against
S. aureus
and
S. pneumoniae
were 43 and 10, respectively. The 24-h free-drug AUC/MIC ratios associated with net stasis for ACT-292706 against
S. aureus
and
S. pneumoniae
were 69 and 25, respectively. The stasis PD targets were significantly lower for
S. pneumoniae
(
P
< 0.05) for both compounds. The 1-log-kill AUC/MIC ratio targets were ∼2- to 4-fold higher than stasis targets. Methicillin, penicillin, or ciprofloxacin resistance did not alter the magnitude of the AUC/MIC ratio required for efficacy. These results should be helpful in the design of clinical trials for topoisomerase inhibitors.
Resistance Mechanisms and Clinical Features of Fluconazole-Nonsusceptible Candida tropicalis Isolates Compared with Fluconazole-Less-Susceptible Isolates
Authors: Choi Min Ji , Won Eun Jeong , Shin Jong Hee , Kim Soo Hyun , Lee Wee-Gyo , Kim Mi-Na , Lee Kyungwon , Shin Myung Geun , Suh Soon Pal , Ryang Dong Wook , Im Young Jun
Published: April 2016

We investigated the azole resistance mechanisms and clinical features of fluconazole-nonsusceptible (FNS) isolates of
Candida tropicalis
recovered from Korean surveillance cultures in comparison with fluconazole-less-susceptible (FLS) isolates. Thirty-five clinical isolates of
C. tropicalis
, comprising 9 FNS (fluconazole MIC, 4 to 64 μg/ml), 12 FLS (MIC, 1 to 2 μg/ml), and 14 control (MIC, 0.125 to 0.5 μg/ml) isolates, were assessed.
CDR1
,
MDR1
, and
ERG11
expression was quantified, and the
ERG11
and
UPC2
genes were sequenced. Clinical features of 16 patients with FNS or FLS bloodstream isolates were analyzed. Both FNS and FLS isolates had >10-fold higher mean expression levels of
CDR1
,
MDR1
, and
ERG11
genes than control isolates (
P
values of <0.02 for all). When FNS and FLS isolates were compared, FNS isolates had 3.4-fold higher mean
ERG11
expression levels than FLS isolates (
P
= 0.004), but there were no differences in those of
CDR1
or
MDR1
. Of all 35 isolates, 4 (2 FNS and 2 FLS) and 28 (8 FNS, 11 FLS, and 9 control) isolates exhibited amino acid substitutions in Erg11p and Upc2p, respectively. Both FNS and FLS bloodstream isolates were associated with azole therapeutic failure (3/4 versus 4/7) or uncleared fungemia (4/6 versus 4/10), but FNS isolates were identified more frequently from patients with previous azole exposure (6/6 versus 3/10;
P
= 0.011) and immunosuppression (6/6 versus 3/10;
P
= 0.011). These results reveal that the majority of FNS
C. tropicalis
isolates show overexpression of
CDR1
,
MDR1
, and
ERG11
genes, and fungemia develops after azole exposure in patients with immunosuppression.
Combination Regimens for Treatment of Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections
Authors: Gomez-Simmonds A. , Nelson B. , Eiras D. P. , Loo A. , Jenkins S. G. , Whittier S. , Calfee D. P. , Satlin M. J. , Kubin C. J. , Furuya E. Y.
Published: April 2016

Previous studies reported decreased mortality in patients with carbapenemase-producing
Klebsiella pneumoniae
bloodstream infections (BSIs) treated with combination therapy but included carbapenem-susceptible and -intermediate isolates, as per revised CLSI breakpoints. Here, we assessed outcomes in patients with BSIs caused by phenotypically carbapenem-resistant
K. pneumoniae
(CRKP) according to the number of
in vitro
active agents received and whether an extended-spectrum beta-lactam (BL) antibiotic, including meropenem, or an extended-spectrum cephalosporin was administered. We retrospectively reviewed CRKP BSIs at two New York City hospitals from 2006 to 2013, where all isolates had meropenem or imipenem MICs of ≥4 μg/ml. Univariate and multivariable models were created to identify factors associated with mortality. Of 141 CRKP BSI episodes, 23% were treated with a single active agent (SAA), 26% were treated with an SAA plus BL, 28% were treated with multiple active agents (MAA), and 23% were treated with MAA plus BL. Ninety percent of isolates had meropenem MICs of ≥16 μg/ml. Thirty-day mortality was 33% overall and did not significantly differ across the four treatment groups in a multivariable model (
P
= 0.4); mortality was significantly associated with a Pitt bacteremia score of ≥4 (odds ratio [OR], 7.7; 95% confidence interval [CI], 3.2 to 18.1;
P
= 0.1), and immunosuppression was protective (OR, 0.4; 95% CI, 0.2 to 1.0;
P
= 0.04). Individual treatment characteristics were also not significantly associated with outcome, including use of SAAs versus MAA (26% versus 38%,
P
= 0.1) or BL versus no BL (26% versus 39%,
P
= 0.1). In summary, in patients with CRKP BSIs caused by isolates with high carbapenem MICs, the role of combination therapy remains unclear, highlighting the need for prospective studies to identify optimal treatment regimens.
The YsrS Paralog DygS Has the Capacity To Activate Expression of the Yersinia enterocolitica Ysa Type III Secretion System
Authors: Walker Kimberly A. , Griggs Lauren A. , Obrist Markus , Bode Addys , Summers R. Patrick , Miller Virginia L.
Published: April 2016

The
Yersinia enterocolitica
Ysa type III secretion system (T3SS) is associated with intracellular survival, and, like other characterized T3SSs, it is tightly controlled. Expression of the
ysa
genes is only detected following growth at low temperatures (26°C) and in high concentrations of sodium chloride (290 mM) in the medium. The YsrSTR phosphorelay (PR) system is required for
ysa
expression and likely responds to NaCl. During our investigations into the Ysr PR system, we discovered that genes YE3578 and YE3579 are remarkably similar to
ysrR
and
ysrS
, respectively, and are probably a consequence of a gene duplication event. The amino acid differences between YE3578 and
ysrR
are primarily clustered into two short regions. The differences between YE3579 and
ysrS
are nearly all located in the periplasmic sensing domain; the cytoplasmic domains are 98% identical. We investigated whether these paralogs were capable of activating
ysa
gene expression. We found that the sensor paralog, named DygS, is capable of compensating for loss of
ysrS
, but the response regulator paralog, DygR, cannot complement a
ysrR
gene deletion. In addition, YsrR, but not DygR, interacts with the histidine phosphorelay protein YsrT. Thus, DygS likely activates
ysa
gene expression in response to a signal other than NaCl and provides an example of a phosphorelay system in which two sensor kinases feed into the same regulatory pathway.

IMPORTANCE
All organisms need mechanisms to promote survival in changing environments. Prokaryotic phosphorelay systems are minimally comprised of a histidine kinase (HK) that senses an extracellular stimulus and a response regulator (RR) but can contain three or more proteins. Through gene duplication, a unique hybrid HK was created. We show that, while the hybrid appears to retain all of the phosphorelay functions, it responds to a different signal than the original. Both HKs transmit the signal to the same RR, which activates a promoter that transcribes a set of genes encoding a type III secretion system (T3SS) whose function is not yet evident. The significance of this work lies in finding that two HKs regulate this T3SS, highlighting its importance.
Diminution of falsely elevated tumour markers following immunosuppression for systemic lupus erythematosus with neurological involvement
Authors: Bevan Jonathan , Richardson Michael
Published: April 2016

We describe the case of a patient with a long history of undifferentiated connective tissue disease who developed headache, ataxia and orofacial dyskinesia attributed to a diagnosis of systemic lupus erythematosus (SLE). Gross elevation of the concentration of several plasma tumour markers (CEA, CA-125, CA19-9, CA15-3) was detected in the absence of malignancy. These markers fell significantly within a month of starting immunosuppressive therapy alongside clinical improvement. Caution should be taken in the interpretation of plasma tumour markers in patients with connective tissue disease.
Dead space closure with quilting suture versus conventional closure with drainage for the prevention of seroma after mastectomy for breast cancer (QUISERMAS): protocol for a multicentre randomised controlled trial
Authors: Ouldamer Lobna , Bonastre Julia , Brunet-Houdard Solène , Body Gilles , Giraudeau Bruno , Caille Agnès
Published: April 2016

Introduction

Postoperative wound seroma is common after mastectomy. This complication is associated with significant impact on patient outcomes and healthcare costs. The optimal closure approach for seroma prevention remains unknown but some evidence suggests that quilting suture of the dead space could lower the incidence of seroma. The aim of this trial is to compare seroma formation using quilting suture versus conventional closure with drainage in patients undergoing mastectomy.

Methods and analysis

This is a multicentre, superiority, randomised controlled trial in women undergoing mastectomy with or without axillary involvement. Exclusion criteria include indication of bilateral mastectomy or immediate reconstruction and any physical or psychiatric condition that could impair patient's ability to cooperate with postoperative data collection or that do not allow an informed consent. 320 participants will be randomised in a 1:1 ratio to receive either quilting suture or conventional wound closure with drain. The primary outcome is seroma requiring either aspiration or surgical intervention within 21 days following mastectomy. Secondary outcomes include seroma regardless of whether or not it requires an intervention, surgical site infection, pain score, cosmetic result, patient's quality of life, costs and cost-effectiveness. The primary analysis will be an intention-to treat analysis performed with a χ2test (or Fisher's exact test).

Ethics and dissemination

Written informed consent will be obtained from all participants. This study was approved by Tours Research ethics committee (CPP TOURS—Region Centre—Ouest 1, 2014-R20, 16 December 2014). Study findings will be published in peer-reviewed journals and presented at relevant national and international breast cancer conferences.

Trial registration number

NCT02263651.
Disability pension due to common mental disorders and subsequent suicidal behaviour: a population-based prospective cohort study
Authors: Rahman Syed Ghulam , Alexanderson Kristina , Jokinen Jussi , Mittendorfer-Rutz Ellenor
Published: April 2016

Objective

Adverse health outcomes, including suicide, in individuals on disability pension (DP) due to mental diagnoses have been reported. However, scientific knowledge on possible risk factors for suicidal behaviour (suicide attempt and suicide) in this group, such as age, gender, underlying DP diagnoses, comorbidity and DP duration and grade, is surprisingly sparse. This study aimed to investigate associations of different measures (main and secondary diagnoses, duration and grade) of DP due to common mental disorders (CMD) with subsequent suicidal behaviour, considering gender and age differences.

Design

Population-based prospective cohort study based on Swedish nationwide registers.

Methods

A cohort of 46 515 individuals aged 19–64 years on DP due to CMD throughout 2005 was followed-up for 5 years. In relation to different measures of DP, univariate and multivariate HRs and 95% CIs for suicidal behaviour were estimated by Cox regression. All analyses were stratified by gender and age.

Results

During 2006–2010, 1036 (2.2%) individuals attempted and 207 (0.5%) completed suicide. Multivariate analyses showed that a main DP diagnosis of ‘stress-related mental disorders’ was associated with a lower risk of subsequent suicidal behaviour than ‘depressive disorders’ (HR range 0.4–0.7). Substance abuse or personality disorders as a secondary DP diagnosis predicted suicide attempt in all subgroups (HR range 1.4–2.3) and suicide in women and younger individuals (HR range 2.6–3.3). Full-time DP was associated with a higher risk of suicide attempt compared with part-time DP in women and both age groups (HR range 1.4–1.7).

Conclusions

Depressive disorders as the main DP diagnosis and substance abuse or personality disorders as the secondary DP diagnosis were risk markers for subsequent suicidal behaviour in individuals on DP due to CMD. Particular attention should be paid to younger individuals on DP due to anxiety disorders because of the higher suicide risk.
Is health impact assessment useful in the context of trade negotiations? A case study of the Trans Pacific Partnership Agreement
Authors: Hirono Katherine , Haigh Fiona , Gleeson Deborah , Harris Patrick , Thow Anne Marie , Friel Sharon
Published: April 2016

Objective

The Trans Pacific Partnership Agreement (TPP) is a recently concluded free trade agreement involving Australia and 11 other Pacific-rim nations, which has the potential for far-reaching impacts on public health. A health impact assessment (HIA) was carried out during the negotiations to determine the potential future public health impact in Australia and to provide recommendations to mitigate potential harms. This paper explores the findings and outcomes of the HIA, and how this approach can be used to provide evidence for public health advocacy.

Design

A modified version of the standard HIA process was followed. The HIA was led by technical experts in HIA, trade policy, and health policy, in collaboration with advocacy organisations concerned with the TPP and health. The HIA reviewed the provisions in leaked TPP text in order to determine their potential impact on future health policy. As part of this process, researchers developed policy scenarios in order to examine how TPP provisions may affect health policies and their subsequent impact to health for both the general and vulnerable populations. The four policy areas assessed were the cost of medicines, tobacco control, alcohol control and food labelling.

Results

In all areas assessed, the HIA found that proposed TPP provisions were likely to adversely affect health. These provisions are also likely to more adversely affect the health of vulnerable populations.

Conclusions

The HIA produced relevant evidence that was useful in advocacy efforts by stakeholders, and engaging the public through various media platforms.
Effects of body mass index, tobacco smoking, alcohol drinking and solid fuel use on the risk of asthma: Individual Participant Data (IPD) meta-analysis of 175 000 individuals from 51 nationally representative surveys
Authors: Patra Jayadeep , Maher Yurie Izawa , Mishra Sujata , Bhatia Mehak , Alam Dewan , Malini Doki S , Gupta Prakash C , Jha Prabhat
Published: April 2016

Background

We assessed the relationship of body mass index (BMI), smoking, drinking and solid fuel use (r; SFU), and the individual and combined effects of these factors on wheezing symptoms (WS) and on diagnosed asthma (DA).

Methods

We analysed 175 000 individuals from 51 nationally representative surveys, using self-reports of WS and DA as the measures of asthma. The fixed-effects and random-effects estimates of the pooled ORs between asthma and underweight (BMI <18.5 kg/m2), obesity (BMI ≥30 kg/m2), smoking, drinking and SFU were reported.

Results

The pooled risks of all individual risk factors were significantly associated with WS and DA (with the exception of current smoking with DA in women and SFU with DA in both genders). Stronger dose–response relationships were seen in women for smoking amounts and duration; BMI showed stronger quadratic relationships. The combined risks were generally larger in women than in men, with significant risks for underweight (OR=2.73) as well as obese (OR=2.00) smokers for WS (OR=2.13 and OR=1.58 for DA, respectively). The magnitude of the combined effects from low/high BMI, smoking and drinking were also consistently higher among women than among men in WS and DA. SFU among underweight smokers also had positive association with WS (men and women) and DA (women).

Conclusions

BMI, smoking, drinking and SFU—in combination—are associated with double or triple the risk of development of asthma. These risk factors might help explain the wide variation in asthma burden across countries.
Patient and public involvement in emergency care research
Authors: Hirst Enid , Irving Andy , Goodacre Steve
Published: April 2016

Patients participate in emergency care research and are the intended beneficiaries of research findings. The public provide substantial funding for research through taxation and charitable donations. If we do research to benefit patients and the public are funding the research, then patients and the public should be involved in the planning, prioritisation, design, conduct and oversight of research, yet patient and public involvement (or more simply, public involvement, since patients are also members of the public) has only recently developed in emergency care research. In this article, we describe what public involvement is and how it can help emergency care research. We use the development of a pioneering public involvement group in emergency care, the Sheffield Emergency Care Forum, to provide insights into the potential and challenges of public involvement in emergency care research.
Evaluation and optimisation of propofol pharmacokinetic parameters in cats for target‐controlled infusion
Authors: Cattai A. , Pilla T. , Cagnardi P. , Zonca A. , Franci P.
Published: April 2016

The aim of this study was to develop and evaluate a pharmacokinetic model‐driven infusion of propofol in premedicated cats. In a first step, propofol (10 mg/kg) was administered intravenously over 60 seconds to induce anaesthesia for the elective neutering of seven healthy cats, premedicated intramuscularly with 0.3 mg/kg methadone, 0.01 mg/kg medetomidine and 2 mg/kg ketamine. Venous blood samples were collected over 240 minutes, and propofol concentrations were measured via a validated high‐performance liquid chromatography assay. Selected pharmacokinetic parameters, determined by a three‐compartment open linear model, were entered into a computer‐controlled infusion pump (target‐controlled infusion‐1 (TCI‐1)). In a second step, TCI‐1 was used to induce and maintain general anaesthesia in nine cats undergoing neutering. Predicted and measured plasma concentrations of propofol were compared at specific time points. In a third step, the pharmacokinetic parameters were modified according to the results from the use of TCI‐1 and were evaluated again in six cats. For this TCI‐2 group, the median values of median performance error and median absolute performance error were −1.85 per cent and 29.67 per cent, respectively, indicating that it performed adequately. Neither hypotension nor respiratory depression was observed during TCI‐1 and TCI‐2. Mean anaesthesia time and time to extubation in the TCI‐2 group were 73.90 (±20.29) and 8.04 (±5.46) minutes, respectively.
Irrigation practices, nutrient applications, and mulches affect soil nutrient dynamics in a young Merlot (Vitis viniferaL.) vineyard
Authors: Hannam Kirsten D. , Neilsen Gerry H. , Forge Thomas A. , Neilsen Denise , Losso Istvan , Jones Melanie D. , Nichol Craig , Fentabil Mesfin M.
Published: April 2016

There is growing interest among commercial wine grape (Vitis vinifera L.) growers in reducing water and fertilizer consumption, but little information exists on how best to combine conservative irrigation and soil management practices in the vineyard. In a 3-year-old Merlot vineyard in the semi-arid Okanagan Valley, British Columbia, the interactive effects of resource-conserving micro-irrigation (drippers or microsprinkers), nutrient applications (fertigation or compost), and surface mulching (wood and bark chips) on nitrogen (N) and phosphorus (P) dynamics in the wetted zone of surface soils were examined throughout the growing season using ion-exchange resins. Treatment differences in soil carbon and major nutrient pools, temperature, and moisture were also measured. Higher NO3-N was adsorbed by resins buried under drippers than under microsprinklers except in mulched plots, where NO3-N was uniformly low. By enhancing soil carbon availability and moderating soil microclimate, surface mulches may have promoted microbial immobilisation of N. Compost applications increased soil ortho-P levels, especially on mulched plots, suggesting that both P inputs (from compost) and enhanced microbial biomass (from mulch) promoted soil P cycling. Future work will examine the interactive effects of these resource-efficient practices on leaching losses, greenhouse gas emissions, crop productivity, and fruit quality.
Solute dynamics and the Ontario nitrogen index: I. Chloride leaching
Authors: Reynolds W. Daniel , Drury Craig F. , Parkin Gary W. , Lauzon John D. , Saso Joseph K. , Zhang Tiequan , Liu Kui , Welacky Tom W. , Yang Xueming , Tan Chin S. , Calder Wayne , Oloya Tom O. , Reid D. Keith
Published: April 2016

The nitrogen (N) index for humid temperate southern Ontario, Canada (Ontario N index) incorporates previous and current crop type, fertilizer and (or) manure management, and hydrologic soil group (HSG) to estimate risk for contamination of tile drainage water and groundwater by nitrate leached below the primary crop root zone (top 60 cm of soil). The Ontario N index has received limited ground-truthing, and the leaching component was assessed using chloride tracer (ClTR) on five soils (one sandy loam, two loams, and two clay loams) representing four HSG-based risk levels (HSG-A, high risk; HSG-B, medium risk; HSG-C, low risk; HSG-D, very low risk). A square-wave pulse of ClTR was applied to the soil surfaces in fall 2007 as KCl, and movement and loss of ClTR was tracked over 1–1.2 years using monthly soil core samples collected from the top 60–80 cm. For all five soils, 60–96% of ClTR was leached out of the primary crop root zone (below 60 cm depth) during the noncropping period (October 2007 to March 2008 inclusive), and >80% was leached out of the root zone within 1 year. The percentage of ClTR that leached did not correlate with precipitation or HSG designation, but produced significant (P < 0.05) power function regressions with minimum and harmonic mean saturated soil hydraulic conductivity (Ksat) measured in the top 50–60 cm. ClTR leaching rate appeared to be controlled primarily by Ksat in a manner consistent with infiltration and solute transport theory. It was consequently proposed that solute leaching loss versus Ksat relationships may improve N index risk estimates for both southern Ontario and other humid temperate regions.
Preventive and Abortive Strategies for Stimulation Based Control of Epilepsy: A Computational Model Study
Authors: Koppert Marc , Kalitzin Stiliyan , Velis Demetrios , Lopes Da Silva Fernando , Viergever Max A.
Published: April 2016

Epilepsy is a condition in which periods of ongoing normal EEG activity alternate with periods of oscillatory behavior characteristic of epileptic seizures. The dynamics of the transitions between the two states are still unclear. Computational models provide a powerful tool to explore the underlying mechanisms of such transitions, with the purpose of eventually finding therapeutic interventions for this debilitating condition. In this study, the possibility to postpone seizures elicited by a decrease of inhibition is investigated by using external stimulation in a realistic bistable neuronal model consisting of two interconnected neuronal populations representing pyramidal cells and interneurons. In the simulations, seizures are induced by slowly decreasing the conductivity of GABA[Formula: see text] synaptic channels over time. Since the model is bistable, the system will change state from the initial steady state (SS) to the limit cycle (LS) state because of internal noise, when the inhibition falls below a certain threshold. Several state-independent stimulations paradigms are simulated. Their effectiveness is analyzed for various stimulation frequencies and intensities in combination with periodic and random stimulation sequences. The distributions of the time to first seizure in the presence of stimulation are compared with the situation without stimulation. In addition, stimulation protocols targeted to specific subsystems are applied with the objective of counteracting the baseline shift due to decreased inhibition in the system. Furthermore, an analytical model is used to investigate the effects of random noise. The relation between the strength of random noise stimulation, the control parameter of the system and the transitions between steady state and limit cycle are investigated. The study shows that it is possible to postpone epileptic activity by targeted stimulation in a realistic neuronal model featuring bistability and that it is possible to stop seizures by random noise in an analytical model.
A Goal Programming Model for Selection and Scheduling of Advertisements on Online News Media
Authors: Manik Prerna , Gupta Anshu , Jha P. C. , Govindan Kannan
Published: April 2016

Digital revolution has resulted in a paradigm shift in the field of marketing with online advertising becoming increasingly popular as it offers the reach, range, scale and interactivity to organizations to influence their target customers. Moreover, web advertisement is the primary revenue stream for several websites that provide free services to internet users. The website management team needs to do a lot of planning and optimally schedule various advertisements (ads) to maximize revenue, taking care of advertisers’ needs under system constraints. In this paper, we have considered the case of news websites that provide news to its viewers for free with ads as the primary source of their revenue. The considered news website consists of many webpages with different banners for advertisement. Each banner consists of different number of partitions and cost per partition varies for different rectangular banners. Many ads compete with each other for their placement on a webpage on a specific banner, based on partition requirement, at specific time interval(s). Here, we have formulated a mixed integer 0–1 linear programming advertisement scheduling problem to maximize the revenue over planning horizon divided into time intervals under various system and technical constraints. A case is presented to show the applicability of the model. Branch and bound integer programming and goal programming techniques have been used to solve the formulated problem.
Physical and optical properties of magnesium sulfoborate glasses doped Dy3+ ions
Authors: Dalhatu S. A. , Deraman Karim , Hussin R.
Published: April 2016

The optical properties of alkaline earth borate glasses doped with rare earth are attractive field of research due to many optical applications. We have concentrated on the physical and optical properties of MgO–SO4–B2O3 glass with different concentrations of Dy[Formula: see text] ions. The samples of glass were prepared using the melting quenching technique. The physical parameter and optical properties of the prepared glass were determined. It was observed that the density of the glass samples increased and the molar volume reduced with respect to Dy[Formula: see text] ions content. Dy[Formula: see text]: MgO–SO4–B2O3 glass displayed 10 absorption bands with hypersensitive transition around 1265 nm (6H[Formula: see text]F[Formula: see text]). Two intense luminescence emissions were observed at 482 nm (4F[Formula: see text]H[Formula: see text]: blue) and 573 nm (4F[Formula: see text]H[Formula: see text]: yellow) and weak band at 662 nm (4F[Formula: see text]H[Formula: see text]: red) with excitation wavelength 380 nm. A strong enhancement in the emission peaks at 573 nm in the yellow region was observed with the 0.07 mol% concentration of dysprosium oxide, which may assign to the energy transfer from Mg[Formula: see text] to Mg[Formula: see text] ions. Beyond the optimum concentration, contrary result was observed.
Simulation on the aggregation process of spherical particle confined in a spherical shell
Authors: Wang J. , Xu J. J. , Zhang L.
Published: April 2016

The aggregation process of spherical particles confined in a spherical shell was studied by using a diffusion-limited cluster–cluster aggregation (DLCA) model. The influence of geometrical confinement and wetting-like properties of the spherical shell walls on the particle concentration profile, aggregate structure and aggregation kinetics had been explored. The results show that there will be either depletion or absorption particles near the shell walls depending on the wall properties. It is observed that there are four different types of density distribution which can be realized by modifying the property of the inner or outer spherical shell wall. In addition, the aggregate structure will become more compact in the confined spherical shell comparing to bulk system with the same particle volume fraction. The analysis on the aggregation kinetics indicates that geometrical confinement will promote the aggregation process by reducing the invalid movement of the small aggregates and by constraining the movement of those large aggregates. Due to the concave geometrical characteristic of the outer wall of the spherical shell, its effects on the aggregating kinetics and the structure of the formed aggregates are more evident than those of the inner wall. This study will provide some instructive information of controlling the density distribution of low-density porous polymer hollow spherical shells and helps to predict gel structures developed in confined geometries.
Pentamodal behaviors and acoustic bandgaps of asymmetric pentamode elastic metamaterials
Authors: Huang Yan , Lu Xuegang , Liang Gongying , Xu Zhuo
Published: April 2016

The asymmetric pentamode metamaterial structure which is built by connecting double-cones with different cross-section shapes (regular triangle, square, pentagon and hexagon) to form diamond lattice is proposed in this paper. Then its phonon band structure is calculated by finite-element method (FEM), and its pentamodal behaviors and acoustic bandgaps are studied in detail. Results show that in the process of adjusting geometrical parameters, the asymmetric case performs similar pentamodal behaviors [ratio of bulk modulus to shear modulus [Formula: see text] and single-mode bandgap (SBG)] with the symmetric cases. And the asymmetric case not only remains the intrinsic complete bandgap (CBG) of mode 12-13 like symmetric cases, but also opens new and wide CBG of mode 10-11 and mode 14-15 for appropriate parameters. Therefore, introducing structural asymmetry should be an effective way to open CBG in pentamode elastic metamaterials.
Optical waveguide switch through magnetic reflectance wall
Authors: Fang Yuntuan , Ni Zhiyao , Yang Lixia
Published: April 2016

We propose a new design to achieve optical waveguide switch. We construct a photonic crystal waveguide with one yttrium iron garnet (YIG) rod array on the two sides of the waveguide. Through the mode analysis, we find in special frequency range a few YIG rods under magnetic field can form the magnetic reflectance wall that blocks the light flow. Removing the magnetic field will delete the reflection wall and let the blocked light to be switched on.
Normal Form of Saddle-Node-Hopf Bifurcation in Retarded Functional Differential Equations and Applications
Authors: Jiang Heping , Jiang Jiao , Song Yongli
Published: April 2016

In this paper, we firstly employ the normal form theory of delayed differential equations according to Faria and Magalhães to derive the normal form of saddle-node-Hopf bifurcation for the general retarded functional differential equations. Then, the dynamical behaviors of a Leslie–Gower predator–prey model with time delay and nonmonotonic functional response are considered. Specially, the dynamical classification near the saddle-node-Hopf bifurcation point is investigated by using the normal form and the center manifold approaches. Finally, the numerical simulations are employed to support the theoretical results.
Chaos and Synchronization in Complex Fractional-Order Chua’s System
Authors: Lin Xiaoran , Zhou Shangbo , Li Hua
Published: April 2016

In this paper, chaos in complex-order Chua’s system and its chaotic synchronization for secure communication are studied based on the fractional derivative investigated. Chaos in complex-order Chua’s system is illustrated by presenting its waveform graphs, states diagrams and bifurcation graphs. The dynamic behaviors in the complex-order Chua’s system and time-delayed Chua’s system are compared. In addition, the largest Lyapunov exponents of normal and time-delayed Chua’s systems are calculated and verified by numerical simulations. The experiment indicates that the chaos in such Chua’s system can achieve two channel communications.
Persistence, Turing Instability and Hopf Bifurcation in a Diffusive Plankton System with Delay and Quadratic Closure
Authors: Zhao Jiantao , Wei Junjie
Published: April 2016

A reaction–diffusion plankton system with delay and quadratic closure term is investigated to study the interactions between phytoplankton and zooplankton. Sufficient conditions independent of diffusion and delay are obtained for the persistence of the system. Our conclusions show that diffusion can induce Turing instability, delay can influence the stability of the positive equilibrium and induce Hopf bifurcations to occur. The computational formulas which determine the properties of bifurcating periodic solutions are given by calculating the normal form on the center manifold, and some numerical simulations are carried out for illustrating the theoretical results.
On torus knots and unknots
Authors: Oberti Chiara , Ricca Renzo L.
Published: April 2016

A comprehensive study of geometric and topological properties of torus knots and unknots is presented. Torus knots/unknots are particularly symmetric, closed, space curves, that wrap the surface of a mathematical torus a number of times in the longitudinal and meridian direction. By using a standard parametrization, new results on local and global properties are found. In particular, we demonstrate the existence of inflection points for a given critical aspect ratio, determine the location and prescribe the regularization condition to remove the local singularity associated with torsion. Since to first approximation total length grows linearly with the number of coils, its nondimensional counterpart is proportional to the topological crossing number of the knot type. We analyze several global geometric quantities, such as total curvature, writhing number, total torsion, and geometric ‘energies’ given by total squared curvature and torsion, in relation to knot complexity measured by the winding number. We conclude with a brief presentation of research topics, where geometric and topological information on torus knots/unknots finds useful application.
ITERATED FUNCTION SYSTEMS ON FUNCTIONS OF BOUNDED VARIATION
Authors: LA TORRE DAVIDE , MENDIVIL FRANKLIN , VRSCAY EDWARD R.
Published: April 2016

We show that under certain hypotheses, an iterated function system on mappings (IFSM) is a contraction on the complete space of functions of bounded variation (BV). It then possesses a unique attractor of BV. Some BV-based inverse problems based on the Collage Theorem for contraction maps are considered.
STUDY OF NICKEL ION RELEASE IN SIMULATED BODY FLUID FROM C+-IMPLANTED NICKEL TITANIUM ALLOY
Authors: SHAFIQUE MUHAMMAD AHSAN , MURTAZA G. , SAADAT SHAHZAD , ZAHEER ZEESHAN , SHAHNAWAZ MUHAMMAD , UDDIN MUHAMMAD K. H. , AHMAD RIAZ
Published: April 2016

Nickel ion release from NiTi shape memory alloy is an issue for biomedical applications. This study was planned to study the effect of C[Formula: see text] implantation on nickel ion release and affinity of calcium phosphate precipitation on NiTi alloy. Four annealed samples are chosen for the present study; three samples with oxidation layer and the fourth without oxidation layer. X-ray diffraction (XRD) spectra reveal amorphization with ion implantation. Proton-induced X-ray emission (PIXE) result shows insignificant increase in Ni release in simulated body fluid (SBF) and calcium phosphate precipitation up to [Formula: see text][Formula: see text]ions/cm2. Then Nickel contents show a sharp increase for greater ion doses. Corrosion potential decreases by increasing the dose but all the samples passivate after the same interval of time and at the same level of [Formula: see text] in ringer lactate solution. Hardness of samples initially increases at greater rate (up to [Formula: see text][Formula: see text]ions/cm[Formula: see text] and then increases with lesser rate. It is found that [Formula: see text][Formula: see text]ions/cm2 ([Formula: see text] is a safer limit of implantation on NiTi alloy, this limit gives us lesser ion release, better hardness and reasonable hydroxyapatite incubation affinity.
IN VITRO AND IN VIVO DEGRADATION OF A TWISTED SILK FIBROIN–POLY(LACTIC-CO-GLYCOLIC ACID) FIBER COMPOSITE ROPE-LIKE SCAFFOLD AND CHANGES IN ITS MECHANICAL PROPERTIES
Authors: ZHANG WENYUAN , YANG YADONG , ZHANG KEJI , LI YING , FANG GUOJIAN
Published: April 2016

Natural silk fibroin fiber is slowly degraded, which makes it difficult to be replaced quickly by regenerating tissues of tissue engineering. We used poly(lactic-co-glycolic acid) (PLGA, lactic acid:glycolic acid [Formula: see text] 10:90) fibers to adjust the overall degradation rate of the scaffolds. This study fabricated a three-strand helical composite rope-like scaffold from silk fibroin and PLGA fibers (silk fibroin:PLGA [Formula: see text] 36:64) using a twisting method. In vitro and in vivo degradation experiments were performed over 16 weeks. Results suggest that the in vitro and in vivo degradation tendencies of the scaffold were similar, with mass loss lagging behind mechanical property loss. The speed of degradation in vivo was faster than that in vitro. Mechanical property loss of the scaffold was fast during the first three weeks, when mass loss was slow. Mass loss rate accelerated from weeks 3 to 8. The mass and mechanical properties were relatively stable from 8 to 16 weeks. After 16 weeks of degradation, the scaffold still had considerably strong mechanical properties. The scaffold showed a reasonable and suitable degradation speed with good histocompatibility for ligament tissue engineering.
TO STUDY THE EFFECTS OF INTRASTROMAL CORNEAL RING GEOMETRY AND SURGICAL CONDITIONS ON THE POSTSURGICAL OUTCOMES THROUGH FINITE ELEMENT ANALYSIS
Authors: KHAN SALMAN N. , SHIAKOLAS PANOS S.
Published: April 2016

Intrastromal corneal ring (ICR) is a transparent circular implant inserted in the cornea to provide structural support in an attempt to alleviate preexisting refractive errors. This is a surgical procedure whose success depends on control parameters such as, ICR geometry which includes ICR thickness and diameter, and surgical conditions which includes ICR implantation depth and diameter of corneal pocket. This research utilizes finite element (FE) analysis techniques to develop a high fidelity and computationally efficient three-dimensional axisymmetric cornea model to study the relative effects of ICR implant geometry and surgical conditions on the postsurgical shape of the cornea utilizing corneal apical displacement results. The FE analysis results indicate that ICR implantation reduces myopia, and the amount of myopic rectification is dependent on the control parameters which include ICR geometry and surgical conditions. The results show that an increase in ICR thickness leads to an increase in myopic rectification, whereas an increase in ICR radius leads to a decrease in myopic rectification. ICR implantation depth analysis results suggest that corneal depth of 40–75% provides steady myopic rectification. Corneal pocket diameter analysis revealed that smaller corneal pockets lead to increase in myopic rectification. Overall, the FE model results are in qualitative agreement with published clinical studies. Finally, the combined impact of the control parameters on myopic rectification was studied by conducting a sensitivity analysis and an equation relating myopic rectification with control parameters was developed utilizing simple linear regression analysis.
EFFECTS OF HYPERTENSION AND PRESSURE GRADIENT IN A HUMAN CEREBRAL ANEURYSM USING FLUID STRUCTURE INTERACTION SIMULATIONS
Authors: VALENCIA ALVARO , TORRES FRANCISCO
Published: April 2016

Fluid–structure interaction (FSI) simulations were carried out in a human cerebral aneurysm model with the objective of quantifying the effects of hypertension and pressure gradient on the behavior of fluid and solid mechanics. Six FSI simulations were conducted using a hyperelastic Mooney–Rivlin model. Important differences in wall shear stress (WSS), wall displacements, and effective von Mises stress are reported. The hypertension increases wall stress and displacements in the aneurysm region; however, the effects of hypertension on the hemodynamics in the aneurysm region were small. The pressure gradient affects the WSS in the aneurysm and also the displacement and wall stress on the aneurysm. Maximum wall stress with hypertension in the range of rupture strength was found.
Personality Traits Influencing Knowledge Sharing in Student–Supervisor Relationship: A Structural Equation Modelling Analysis
Authors: Memon Mumtaz Ali , Nor Khalil Md , Salleh Rohani
Published: April 2016

Although knowledge sharing (KS) and personality traits are primarily studied in business organisations, these issues are equally important for universities. However, few attempts have been made to investigate the relationship between personality traits and KS, particularly in the context of Malaysian higher education. The present study fills the research gap by examining the effects of personality traits — specifically agreeableness, conscientiousness and openness to experience — on KS in the student–supervisor relationship. Using probability sampling, data was collected from 175 doctoral students. Structural equation modelling was used to test the hypotheses. The findings suggest that agreeableness, conscientiousness and openness to experience are significantly and positively related to the KS behaviours of research supervisors. Openness to experience was revealed to be the most influential factor in the supervisor’s level of KS. This is the first study to investigate the relationship between personality traits and KS in the context of the student–supervisor relationship, thus marking a significant contribution to the KS literature. The findings of this paper have implication for academics and higher education administrators.
Mediation of Perceived Innovation Characteristics on ERP Adoption in Industrial Cluster
Authors: Elangovan N.
Published: April 2016

An industrial cluster, due to its close network of institutions, will experience various pressures that force the industry to have a homogeneous structure, norms, and practices. These pressures can also lead to adoption of innovative technologies. Enterprise Resource Planning (ERP) is perceived as a sophisticated technology and diffuses across the cluster by its innovative characteristics. However, firms in the industrial cluster will have different rate of adoption of technologies due to the varying level of knowledge spillover and a heterogeneous absorptive capacity. This study empirically tests how absorptive capacity mediates the institutional forces and the perceived innovation characteristics towards the ERP adoption in an industrial cluster. Mediation effect and the model validity are tested using SEM technique. The results show that absorptive capacity complements the forces of institutional pressure and the perceived innovation characteristics on ERP adoption. The implications of managing the absorptive capacity for better ERP adoption are discussed.
Multiscale Modeling of Dynamic Characteristics of Carbon Nanotube Reinforced Nanocomposites
Authors: Gajbhiye Sachin O. , Singh S. P.
Published: April 2016

A unique atomic structure of carbon nanotube unveils outstanding properties. This makes it potentially highly valued reinforcing material to strengthen composite materials. The methodology is established in this research paper to investigate the static and dynamic characteristics of the nanocomposites. Repol polypropylene H110MA is used as a matrix material along with the different percentages of single-walled carbon nanotubes (SWCNTs). A concept of representative volume element (RVE) is considered to study the various properties of the nanocomposite material. The carbon–carbon bond of nanotube is modeled using Tersoff–Brenner potential and represented by space frame element. The matrix material properties are tested in the laboratory which are further used to model it and represented by three-dimensional continuum elements. The interaction between nanotube and polymer matrix is modeled using “Lennard–Jones 6-12” potential represented by nonlinear spring elements. The effect of reinforcement, chirality, % volume of SWCNT, atomic vacancy defect and Stone–Wales defect on the properties of nanocomposite are investigated. To see the effect of reinforcement, the eigenvalues of the RVE are extracted for different boundary conditions. The viscoplastic behavior of the matrix material is considered and the rate-dependent characteristics of the nanocomposite are studied. The damping property of the nanocomposite material is also investigated based on the phase lag between stress and strain field by applying harmonic strain at different frequencies.