bluuebunny/crossref_metadata_2025 huggingface dataset:
INFLUENCE OF MILLING TIME ON GROWTH MORPHOLOGY AND MECHANICAL PROPERTIES OF ALUMINUM-SILICON-CARBIDE COMPOSITES
Authors: Ibrahim Mustafa K. , Idris Jamaliah
Published: September 2015

Achieving improved mechanical properties of aluminum (Al) in the composite structures by mixing ceramics is ever-demanding for sundry applications. We synthesize aluminum-silicon-carbide composites via ball milling of aluminum which is reinforced with 5% of the silicon carbide (SiC) powders having particles size of 20 µm. Microstructures of powdered composite is characterized via XRD, EDX, and FESEM measurements. These mixtures are grinded at the speed of 200 rpm in a planetary ball mill for 0, 40, 80, and 120 minutes using zirconium balls as milling media. The ratio of the ball to powder is selected to be 10:1. At room temperature and pressure of 10 ton the mixed powders are die-pressed in a cylindrical stainless steel mold having internal diameter of 12.7 mm. The impact of milling time on the growth morphology (microstructures) and mechanical properties of the prepared Al–SiC (5 wt %) composite are scrutinized. The method mechanical alloying (MA) is comprised of milling, cold pressing, and sintering. The increase in milling time is demonstrated to enhance the hardness of the composites. Furthermore, the highest hardness and superior strength is achieved for 80 minutes of milling. Both the hardness and strength of such composites are decreased beyond this milling time. The excellent features of the results suggest that Al–SiC (5 wt%) composite with the present composition may be potential to fortify the structural network in terms of strength and stiffness.
PERFORMANCE EVALUATION OF ORTHOGONAL-DIAMOND SEARCH OF BLOCK MATCHING ALGORITHM FOR VIDEO CODING
Authors: Hamid Nurul 'Atiqah , Darsono Abdul Majid , Manap Nurulfajar Abdul , Manap Redzuan Abdul
Published: September 2015

Several drawbacks of established fast Block Matching Algorithm (BMA) are the reasons why new fast BMAs are being developed and proposed in these recent years in order to reduce the computational cost while maintaining the quality of the video signal. In this paper, a new algorithm is proposed, namely Orthogonal-Diamond Search (ODS) which employs an orthogonal-shaped search pattern in the first step and then is switched into diamond-shaped search pattern for the next step. Few established algorithm, namely Orthogonal Search (OS), Full Search (FS), Diamond Search (DS) and Hexagon-Diamond Search (HDS) are implemented using MATLAB along with the ODS and their performance are being compared and analyzed in terms of computational complexity, peak signal-to-noise ratio (PSNR), and number of search points. Simulation result shows that the proposed algorithm can find motion vector with fewer number of search points while maintains close performance of video quality with other selected algorithms.
STEADY STATE EQUILIBRIUM OF SHIPS MANEUVERING UNDER COMBINED ACTION OF WIND AND WAVE
Authors: Paroka Daeng , Haris Muhammad Andi , Asri Syamsul
Published: September 2015

Maneuverability is important in ship design stage not only for ship performance but also for safety reason regarding the collision and stability especially in quartering following waves. The International Maritime Organization (IMO) therefore developed maneuvering criteria and collision regulation to ensure the ship safety against collision. This paper discusses maneuvering performance of ship under combined action of wind and wave. The steady state equations of ship maneuvering were numerically solved using the Newton-Rhapson method in order to obtain the drift angle, the rudder angle and the ship forward speed. Results of numerical simulations show that the combined action of wind and wave has significant effect on the drift angle and the rudder angle in the range of wind and wave direction between 20.0 degrees and 120.0 degrees. The ship forward speed significantly changes due to alteration of wind velocity in the wind and wave direction smaller than 40.0 degrees or in the wind and wave direction larger than 140.0 degrees. The wave height has significant effect on the ship forward speed in the wind and wave direction between 20.0 degrees and 80.0 degrees.
APPLIED CLUSTERING ANALYSIS FOR GROUPING BEHAVIOUR OF E-LEARNING USAGE BASED ON MEANINGFUL LEARNING CHARACTERISTICS
Authors: Octaviani Dewi , Othman Mohd Shahizan , Yusof Norazah , Pranolo Andri
Published: September 2015

One of the critical success factors of e-learning is positive interest of students towards e-learning. The majority of activities of current e-learning usage are viewing and downloading. These activities are not meaningful with regard to enhancing learning quality. Due to that, the aim of this paper is to analyze students’ usage based on meaningful learning characteristics by clustering students’ activities and actions during online learning. We first define meaningful learning characteristics (as those which are active, authentic, cooperative, collaborative, and intentional) and associate these with e-learning activities and actions. Then, we analyze the students’ e-learning usage and define the cluster of student’s meaningful characteristics by using the K-Means cluster method. A case study has been conducted based on the e-learning log files of 37 students on Computational Intelligence Course at the Software Engineering Department, Universiti Teknologi Malaysia. The result of this clustering enables us to determine the students with high ratings on these meaningful activities and actions during online learning. We found out that students with high hits on add, update, and edit are included in the high cluster group. On the contrary, students with high hits on the view actions for all e-learning activities are included in the low cluster group. This result may assist instructors while preparing the strategy of computer usage for education, in terms of providing a greater variety of learning activities, which is applicable for any courses.
ASSESSMENT OF INDOOR AIR QUALITY LEVEL AND SICK BUILDING SYNDROME ACCORDING TO THE AGES OF BUILDING IN UNIVERSITI TEKNOLOGI MALAYSIA
Authors: Ahmad Norhidayah , Hassim Mimi Haryani
Published: September 2015

This study was conducted to assess the indoor air quality (IAQ) level of buildings in Universiti Teknologi Malaysia (UTM). The buildings were randomly selected and represent the old building (>10years) and new building (<10 years). The IAQ physical parameters assessed are temperature, relative humidity and air velocity. Meanwhile, the IAQ chemical contaminants studied are carbon dioxide (CO2), carbon monoxide (CO), formaldehyde (HCHO) and total volatile organic compound (TVOC). The results indicate that the old building has good IAQ level compared to the new buildings. The statistical test shows, there is an association between some IAQ physical parameters and the buildings’ ages (p<0.05). On the chemical contaminants, the measurement shows that the concentration of CO2 and HCHO for all studied buildings exceeds the Malaysian acceptable exposure limits. The results also show there is no association between demographic factors and sick building syndrome (SBS) symptoms. The level of workplace condition and SBS symptoms existed in each selected faculty’s buildings was also analyzed. The recommendations for the minimum number of years for maintenance of the indoor conditions have also been suggested based on the indoor air quality guidelines from Malaysia and Singapore. Finally, the appropriate technical and management approach has been suggested based on the some concepts.
THE STUDY ON BIOLOGICAL PH TREATMENT OF ACIDIC PALM OIL MILL EFFLUENT
Authors: Zainol Norazwina , Ismail Siti Mazlifah
Published: September 2015

This study investigated the biological pH treatment of acidic palm oil mill effluent (POME). In this study soil mixed culture (SMC) was acclimatized for 10 days (30°C and 150 rpm) with POME and used as inoculum. Selected factors used in this study were reaction time (3-5 days), temperature (25-30 °C), agitation speed (150-180 rpm), soil to water ratio (1:1 and 1:3) and inoculum types (peat and alluvium inoculum). Response surface method (RSM) was used to design and analyzed experimental data. In this study reaction time gave highest contribution which was at 29.81%. Reaction time was important for microbial growth in biological pH treatment. Interaction between reaction time and agitation speed gave highest contribution which was at 17.21%. Agitation provides a proper mixing on acidic POME and SMC thus increased the microbial activities. In this study, analysis of variance (ANOVA) was used to analyze the experimental data and the coefficient of determination (R2) value of 0.8301 was obtained. This study had proven the application of RSM was useful in experimental data analysis and increased the pH value from 4 to 8.
TIME MARKER GENERATOR USING OPERATIONAL TRANSCONDUCTANE AMPLIFIER
Authors: Srinivasulu Avireni , Tejaswini V. , Pitchaiah T.
Published: September 2015

This letter introduces time marker generator (TMG) using operational transconductance amplifier (OTA). It is composed of comparator (i.e. sine wave to square wave converter), integrator and clipper. The performance of the proposed circuit is examined using Cadence and the model parameters of a 180 nm technology process.  Later, the circuit was built with commercially available OTA (LM 13600), passive components used externally and tested at the outputs of comparator, integrator and clipper. Simulations and experimental results are shown that verify the proposed circuit of time marker generator.
COMPUTATIONAL FLUID DYNAMICS INVESTIGATION ON THE OUTER WING OF FLYING BOAT REMOTE CONTROL MODEL
Authors: Syamsuar S. , Djatmiko E. B , Mujahid A. S , Erwandi Erwandi , Subchane Subchane
Published: September 2015

The experiment of Wing in Surface Effect craft A2B and A2C B type for (1 - 2) seaters prototype are the background of this research. The aerodynamic, hydrodynamic, thrust and weight data of these prototypes were already investigated. The best ratio of Thrust per Weight is around 0.4 from this experience to fulfill the liftoff condition from the water surface.  The step position on the hull as the theoretical prediction of Wing in Surface Effect craft is made (2 to 10)0 from center of gravity, c.g location to the step position. These formulas have been used to designing the Flying Boat remote control model. The whole process to build the remote control model is shown on this paper. The investigation of the outer wing of Flying Boat remote control model had been done to elaborate the aerodynamic and hydrodynamic characteristic. Included the laser photo camera tracking to 3 D model and Computational Fluid Dynamics analysis have been done also. The three dimensions (3 D) figures are evaluated by CATIA software and then these data results were transfer to the input of CFx Computational Fluid Dynamics (CFD) software. The meshing, pressure distribution and forces distributions during hydro planing of outer wing and pontoon of Flying Boat remote control model have been analyzed by CFx Computational Fluid Dynamics software. The Z force on the outer wing and pontoon showed a good result.
THE INFLUENCE OF FREEZE–THAW CYCLES ON UNCONFINED COMPRESSIVE STRENGTH OF CLAY SOILS TREATED WITH LIME
Authors: Firoozi Ali Akbar , Taha Mohd Raihan , Asghar Firoozi Ali , Ahmed Khan Tanveer
Published: September 2015

There are several questions that are not well understood with respect to the long-term stability characteristics of lime-treated clay soils in spite of being used as a conventional technique to improve the properties of clay soils. This paper investigates the influence of freeze-thaw cycles on the unconfined compressive strength of kaolinite and illite mixed with silica sand. The results of this study show that an increase in the number of freeze-thaw cycles decreases the unconfined compressive strength. The role of lime increasing the soil strength is more significant in the case of samples exposed to freeze-thaw cycles compared to those not exposed to freeze-thaw cycles. The effect of freeze-thaw cycles on the dry unit weight and moisture content is insignificant compared to unexposed samples. The maximum volumetric changes occurred in the first freeze-thaw cycle, and afterward, the rate of volume change decreased with an increase in freeze—thaw cycles.
NOX EMISSION MODELLING FROM INDUSTRIAL STEAM BOILERS
Authors: Nasruddin Hairul Nazmin , Azid Azman , Juahir Hafizan , Abdullah Ahmad Makmom , Amran Mohammad Azizi , Mustafa Ahmad Dasuki , Azaman Fazureen
Published: September 2015

Previous researches often emphasize on the sources and effects of air pollutants in the environment and human population. A part of those studies were done in order to explore the spread or distribution pattern of those pollutants, especially regarding the emission from industrial steam boilers. It is very important to evaluate the transfer trend of air pollutants at both local and global scales. In this study, Industrial Source Complex Short Term Version 3 (ISCST3) model has been used to predict the distribution of NOx emitted from industrial steam boilers in the District of Hulu Langat, Selangor. The result of analyses indicates that the emission rates for steam boilers were ranging from 0.0083 kg NOx/hour to as high as 0.2771 kg NOx/hour while the total emission load was 1.9969 kg NOx­/hour. The evaluation on dispersion contour shows that the concentration of NOx was higher in 1-hour reading than 24-hour value. The highest concentration of NOx was predicted to be within 104.65 km2 from the sources of NOx (steam boilers).
Aerodynamic Effects of Unvented Hoods on the Initial Compression Wave Generated by a High-Speed Train Entering a Tunnel
Authors: Xiang Xintao , Xue Leiping , Wang Benlong
Published: September 2015

The influence of unvented hood on the initial compression wave generated by a high-speed train entering a tunnel is investigated using computational fluid dynamics. Comparisons with experimental data are first carried out to verify the numerical model. The relationship between the pressure gradient peaks and main aspect factors is studied by parametric analysis. Influences of train speed, blockage ratio of train to tunnel, section area ratio of hood to tunnel, and hood length are investigated. Based on the numerical results, two empirical formulations are proposed to predict the influence of hood and tunnel geometries on the maximum pressure gradient during the CRH3 entering a tunnel with unvented hood.
Contact Law and Coefficient of Restitution in Elastoplastic Spheres
Authors: Ma Daolin , Liu Caishan
Published: September 2015

A complete contact cycle of an elastoplastic sphere consists of loading and unloading phases. The loading phase may fall into three sequential regimes: elastic, mixed elastic–plastic, and fully plastic. In this paper, we distinguish the transition points among the three regimes via the material hardness and a dimensionless geometric parameter corresponding to the onset of the fully plastic regime. Based on Johnson’s simplified spherical expansion model, together with the well-supported force–indentation relationships in the elastic and fully plastic regimes, we build an analytical approximation for the mixed elastic–plastic regime by enforcing the C1 continuity of a loading force–indentation curve. Unloading responses of the elastoplastic sphere are characterized by an elastic force–indentation relation, which has a Hertzian-type form but takes into account the effects of the strain hardening that occurs in the mixed elastic–plastic regime. We validate the model by comparing with existing quasi-static and impact experiments and show that the model can precisely capture the force–indentation responses. Further validation is performed by employing the proposed compliance model to investigate the coefficient of restitution (COR). We achieve agreement between our numerical results and the experimental data reported in other studies. Particularly, we find that the COR is inversely proportional to the impacting velocity with an exponent equal to 1/6, instead of 1/4 reported by many other models.
Hemodynamics in the Left Atrium and Its Effect on Ventricular Flow Patterns
Authors: Vedula Vijay , George Richard , Younes Laurent , Mittal Rajat
Published: September 2015

In the present study, we investigate the hemodynamics inside left atrium (LA) and understand its impact on the development of ventricular flow patterns. We construct the heart model using dynamic-computed tomographic images and perform simulations using an immersed boundary method based flow solver. We show that the atrial hemodynamics is characterized by a circulatory flow generated by the left pulmonary veins (LPVs) and a direct stream from the right pulmonary veins (RPVs). The complex interaction of the vortex rings formed from each of the PVs leads to vortex breakup and annihilation, thereby producing a regularized flow at the mitral annulus. A comparison of the ventricular flow velocities between the physiological and a simplified pipe-based atrium model shows that the overall differences are limited to about 10% of the peak mitral flow velocity. The implications of this finding on the functional morphology of the left heart as well the computational and experimental modeling of ventricular hemodynamics are discussed.
Implementation of surface energy modification in graphoepitaxy directed self-assembly for hole multiplication
Authors: Doise Jan , Bekaert Joost , Chan Boon Teik , Gronheid Roel , Cao Yi , Hong SungEun , Lin Guanyang , Fishman Daniel , Chakk Yuli , Marzook Taisir
Published: September 2015

A graphoepitaxy directed self-assembly process using cylindrical phase block copolymers is regarded as a promising approach for patterning irregularly distributed contact holes in future integrated circuits. However, control over cylinder profile and open hole rate, among others, needs to be proven before this technique can be implemented in device fabrication. Computational simulation studies predict that selective control over the surface energy of the template bottom and sidewall is crucial for achieving perpendicular cylinders in an adequate range of template dimensions and block copolymer fill levels. This work offers an experimental investigation of the influence of the surface energy on the morphology of the assembly inside the template. For this study, a dedicated surface energy modification is implemented in our process flow. Selective control over the surface energy of the template bottom and sidewall is achieved by using random copolymer brushes. The optimization of surface energy prior to the directed self-assembly allows an improvement of the three-dimensional morphology of the assembly as well as larger process windows in terms of template dimensions and template fill. In addition, a sidewall that has an affinity for the majority block allows for smaller prepattern templates.
An automatic registration method for pre‐ and post‐interventional CT images for assessing treatment success in liver RFA treatment
Authors: Luu Ha Manh , Niessen Wiro , van Walsum Theo , Klink Camiel , Moelker Adriaan
Published: September 2015

Purpose:

In image‐guided radio frequency ablation for liver cancer treatment, pre‐ and post‐interventional CT images are typically used to verify the treatment success of the therapy. In current clinical practice, the tumor zone in the diagnostic, preinterventional images is mentally or manually mapped to the ablation zone in the post‐interventional images to decide success of the treatment. However, liver deformation and differences in image quality as well as in texture of the ablation zone and the tumor area make the mental or manual registration a challenging task. Purpose of this paper is to develop an automatic framework to register the pre‐interventional image to the post‐interventional image.

Methods:

The authors propose a registration approach enabling a nonrigid deformation of the tumor to the ablation zone, while keeping locally rigid deformation of the tumor area. The method was evaluated on CT images of 38 patient datasets from Erasmus MC. The evaluation is based on Dice coefficients of the liver segmentation on both the pre‐interventional and post‐interventional images, and mean distances between the liver segmentations. Additionally, residual distances after registration between corresponding landmarks and local mean surface distance in the images were computed.

Results:

The results show that rigid registration gives a Dice coefficient of 87.9%, a mean distance of the liver surfaces of 5.53 mm, and a landmark error of 5.38 mm, while non‐rigid registration with local rigid deformation has a Dice coefficient of 92.2%, a mean distance between the liver segmentation boundaries near the tumor area of 3.83 mm, and a landmark error of 2.91 mm, where a part of this error can be attributed to the slice spacing in the authors’ CT images.

Conclusions:

This method is thus a promising tool to assess the success of RFA liver cancer treatment.
Sources of variability in consonant perception of normal-hearing listeners
Authors: Zaar Johannes , Dau Torsten
Published: September 2015

Responses obtained in consonant perception experiments typically show a large variability across stimuli of the same phonetic identity. The present study investigated the influence of different potential sources of this response variability. It was distinguished between source-induced variability, referring to perceptual differences caused by acoustical differences in the speech tokens and/or the masking noise tokens, and receiver-related variability, referring to perceptual differences caused by within- and across-listener uncertainty. Consonant-vowel combinations consisting of 15 consonants followed by the vowel /i/ were spoken by two talkers and presented to eight normal-hearing listeners both in quiet and in white noise at six different signal-to-noise ratios. The obtained responses were analyzed with respect to the different sources of variability using a measure of the perceptual distance between responses. The speech-induced variability across and within talkers and the across-listener variability were substantial and of similar magnitude. The noise-induced variability, obtained with time-shifted realizations of the same random process, was smaller but significantly larger than the amount of within-listener variability, which represented the smallest effect. The results have implications for the design of consonant perception experiments and provide constraints for future models of consonant perception.
High sentence predictability increases the fluctuating masker benefit
Authors: Schoof Tim , Rosen Stuart
Published: September 2015

This study examined the effects of sentence predictability and masker modulation type on the fluctuating masker benefit (FMB), the improvement in speech reception thresholds resulting from fluctuations imposed on a steady-state masker. Square-wave modulations resulted in a larger FMB than sinusoidal ones. FMBs were also larger for high compared to low-predictability sentences, indicating that high sentence predictability increases the benefits from glimpses of the target speech in the dips of the fluctuating masker. In addition, sentence predictability appears to have a greater effect on sentence intelligibility when the masker is fluctuating than when it is steady-state.
Not just another Notch
Authors: Nusinovich Yevgeniya
Published: September 2015

Targeting DLL3 with an antibody-drug conjugate eliminates tumor-initiating cells in high-grade pulmonary neuroendocrine cancers.
Axon paths in developing spinal cords
Authors: Hines Pamela J.
Published: September 2015

Axons follow glycerophospholipids to find their way in the developing spinal cord.
Gut microbes make T cells keep the peace
Authors: Mueller Kristen L.
Published: September 2015

Microbes resident in the gut induce an immunoregulatory population of T cells that promote immune homeostasis.
The key to unlocking PARKIN
Authors: Prabakaran Sudhakaran
Published: September 2015

The ubiquitin-like domain of the E3 ligase PARKIN acts as both an inhibitor and an activator of PARKIN activity.
Contact repels neural crest cells
Authors: VanHook Annalisa M.
Published: September 2015

EMT induces an E- to N-cadherin switch that causes neural crest cells to move away from one another upon contact.
STIM-ulating SR calcium uptake
Authors: Gough Nancy R.
Published: September 2015

STIM1 inhibits phospholamban to enhance the activity of the sarcoplasmic reticulum calcium pump in adult cardiac myocytes.
Clinical Outcomes Associated with Polymyxin B Dose in Patients with Bloodstream Infections Due to Carbapenem-Resistant Gram-Negative Rods
Authors: Nelson Brian C. , Eiras Daniel P. , Gomez-Simmonds Angela , Loo Angela S. , Satlin Michael J. , Jenkins Stephen G. , Whittier Susan , Calfee David P. , Furuya E. Yoko , Kubin Christine J.
Published: September 2015

There is significant variation in the use of polymyxin B (PMB), and optimal dosing has not been defined. The purpose of this retrospective study was to evaluate the relationship between PMB dose and clinical outcomes. We included patients with bloodstream infections (BSIs) due to carbapenem-resistant Gram-negative rods who received ≥48 h of intravenous PMB. The objective was to evaluate the association between PMB dose and 30-day mortality, clinical cure at day 7, and development of acute kidney injury (AKI). A total of 151 BSIs were included. The overall 30-day mortality was 37.8% (54 of 151), and the median PMB dosage was 1.3 mg/kg (of total body weight)/day. Receipt of PMB dosages of <1.3 mg/kg/day was significantly associated with 30-day mortality (46.5% versus 26.3%;
P
= 0.02), and this association persisted in multivariable analysis (odds ratio [OR] = 1.58; 95% confidence interval [CI] = 1.05 to 1.81;
P
= 0.04). Eighty-two percent of patients who received PMB dosages of <1.3 mg/kg/day had baseline renal impairment. Clinical cure at day 7 was not significantly different between dosing groups. AKI was more common in patients receiving PMB dosages of ≥250 mg/day (66.7% versus 32.0%;
P
= 0.03), and this association persisted in multivariable analysis (OR = 4.32; 95% CI = 1.15 to 16.25;
P
= 0.03). PMB dosages of <1.3 mg/kg/day were administered primarily to patients with renal impairment, and this dosing was independently associated with 30-day mortality. However, dosages of ≥250 mg/day were independently associated with AKI. These data support the use of PMB without dose reduction in the setting of renal impairment.
Voriconazole Enhances the Osteogenic Activity of Human Osteoblasts
In Vitro
through a Fluoride-Independent Mechanism
Authors: Allen Kahtonna C. , Sanchez Carlos J. , Niece Krista L. , Wenke Joseph C. , Akers Kevin S.
Published: September 2015

Periostitis, which is characterized by bony pain and diffuse periosteal ossification, has been increasingly reported with prolonged clinical use of voriconazole. While resolution of clinical symptoms following discontinuation of therapy suggests a causative role for voriconazole, the biological mechanisms contributing to voriconazole-induced periostitis are unknown. To elucidate potential mechanisms, we exposed human osteoblasts
in vitro
to voriconazole or fluconazole at 15 or 200 μg/ml (reflecting systemic or local administration, respectively), under nonosteogenic or osteogenic conditions, for 1, 3, or 7 days and evaluated the effects on cell proliferation (reflected by total cellular DNA) and osteogenic differentiation (reflected by alkaline phosphatase activity, calcium accumulation, and expression of genes involved in osteogenic differentiation). Release of free fluoride, vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) was also measured in cell supernatants of osteoblasts exposed to triazoles, with an ion-selective electrode (for free fluoride) and enzyme-linked immunosorbent assays (ELISAs) (for VEGF and PDGF). Voriconazole but not fluconazole significantly enhanced the proliferation and differentiation of osteoblasts. In contrast to clinical observations, no increases in free fluoride levels were detected following exposure to either voriconazole or fluconazole; however, significant increases in the expression of VEGF and PDGF by osteoblasts were observed following exposure to voriconazole. Our results demonstrate that voriconazole can induce osteoblast proliferation and enhance osteogenic activity
in vitro
. Importantly, and in contrast to the previously proposed mechanism of fluoride-stimulated osteogenesis, our findings suggest that voriconazole-induced periostitis may also occur through fluoride-independent mechanisms that enhance the expression of cytokines that can augment osteoblastic activity.
Rapid Development of Candida krusei Echinocandin Resistance during Caspofungin Therapy
Authors: Forastiero A. , Garcia-Gil V. , Rivero-Menendez O. , Garcia-Rubio R. , Monteiro M. C. , Alastruey-Izquierdo A. , Jordan R. , Agorio I. , Mellado E.
Published: September 2015

In invasive candidiasis, there has been an epidemiological shift from
Candida albicans
to non-
albicans
species infections, including infections with
C. glabrata
,
C. parapsilosis
,
C. tropicalis
, and
C. krusei
. Although the prevalence of
C. krusei
remains low among yeast infections, its intrinsic resistance to fluconazole raises epidemiological and therapeutic concerns. Echinocandins have
in vitro
activity against most
Candida
spp. and are the first-line agents in the treatment of candidemia. Although resistance to echinocandin drugs is still rare, individual cases of
C. krusei
resistance have been reported in recent years, especially with strains that have been under selective pressure. A total of 15
C. krusei
strains, isolated from the blood, urine, and soft tissue of an acute lymphocytic leukemia patient, were analyzed. Strains developed echinocandin resistance during 10 days of caspofungin therapy. The molecular epidemiology of the isolates was investigated using two different typing methods: PCR-based amplification of the species-specific repetitive polymorphic CKRS-1 sequence and multilocus sequence typing. All isolates were genetically related, and the mechanism involved in decreased echinocandin susceptibility was characterized. Clinical resistance was associated with an increase in echinocandin MICs
in vitro
and was related to three different mutations in hot spot 1 of the target enzyme Fks1p. Molecular evidence of the rapid acquisition of resistance by different mutations in
FKS1
highlights the need to monitor the development of resistance in
C. krusei
infections treated with echinocandin drugs.
pH Manipulation as a Novel Strategy for Treating Mucormycosis
Authors: Trzaska Wioleta J. , Correia Joao N. , Villegas Maria T. , May Robin C. , Voelz Kerstin
Published: September 2015

Mucormycosis is a fatal fungal disease caused by several organisms within the order Mucorales. In recent years, traumatic injury has emerged as a novel risk factor for mucormycosis. Current antifungal therapy is ineffective, expensive, and typically requires extensive surgical debridement. There is thus a pressing need for safe prophylactic treatment that can be rapidly and easily applied to high-risk patients, such as those with major trauma injuries. Acetic acid has been used as a topical treatment for burn wounds for centuries and has proven activity against Gram-negative bacteria. Here, we demonstrate that acetic acid is also highly effective against major pathogenic groups of Mucorales, even at very low concentrations (0.3%). This antifungal effect is not seen with other acids, such as hydrochloric and lactic acid, suggesting that acetic acid activity against Mucorales spores is not solely evoked by low environmental pH. In agreement with this, we demonstrate that the antifungal activity of acetic acid arises from a combination of its ability to potently lower intracellular pH and from pH-independent toxicity. Thus, dilute acetic acid may offer a low-cost, safe, prophylactic treatment for patients at risk of invasive mucormycosis following traumatic injury.
Novel Plasmid-Borne Multidrug Resistance Gene Cluster Including
lsa
(E) from a Linezolid-Resistant Enterococcus faecium Isolate of Swine Origin
Authors: Si Hongbin , Zhang Wan-Jiang , Chu Shengbo , Wang Xiu-Mei , Dai Lei , Hua Xin , Dong Zhimin , Schwarz Stefan , Liu Siguo
Published: September 2015

A novel nonconjugative plasmid of 28,489 bp from a porcine linezolid-resistant
Enterococcus faecium
isolate was completely sequenced. This plasmid harbored a novel type of multiresistance gene cluster that comprised the resistance genes
lnu
(B),
lsa
(E),
spw
,
aadE
,
aphA3
, and two copies of
erm
(B), which account for resistance to macrolides, lincosamides, streptogramins, pleuromutilins, streptomycin, spectinomycin, and kanamycin/neomycin. Structural comparisons suggested that this plasmid might have developed from other enterococcal plasmids by insertion element (IS)-mediated interplasmid recombination processes.
Whole-Genome Sequencing Identifies Emergence of a Quinolone Resistance Mutation in a Case of Stenotrophomonas maltophilia Bacteremia
Authors: Pak Theodore R. , Altman Deena R. , Attie Oliver , Sebra Robert , Hamula Camille L. , Lewis Martha , Deikus Gintaras , Newman Leah C. , Fang Gang , Hand Jonathan , Patel Gopi , Wallach Fran , Schadt Eric E. , Huprikar Shirish , van Bakel Harm , Kasarskis Andrew , Bashir Ali
Published: September 2015

Whole-genome sequences for
Stenotrophomonas maltophilia
serial isolates from a bacteremic patient before and after development of levofloxacin resistance were assembled
de novo
and differed by one single-nucleotide variant in
smeT
, a repressor for multidrug efflux operon
smeDEF
. Along with sequenced isolates from five contemporaneous cases, they displayed considerable diversity compared against all published complete genomes. Whole-genome sequencing and complete assembly can conclusively identify resistance mechanisms emerging in
S. maltophilia
strains during clinical therapy.
Bacillus anthracis
tagO
Is Required for Vegetative Growth and Secondary Cell Wall Polysaccharide Synthesis
Authors: Lunderberg J. Mark , Liszewski Zilla Megan , Missiakas Dominique , Schneewind Olaf
Published: September 2015

Bacillus anthracis
elaborates a linear secondary cell wall polysaccharide (SCWP) that retains surface (S)-layer and associated proteins via their S-layer homology (SLH) domains. The SCWP is comprised of trisaccharide repeats [→4)-β-ManNAc-(1→4)-β-GlcNAc-(1→6)-α-GlcNAc-(1→] and tethered via acid-labile phosphodiester bonds to peptidoglycan. Earlier work identified UDP-GlcNAc 2-epimerases GneY (BAS5048) and GneZ (BAS5117), which act as catalysts of ManNAc synthesis, as well as a polysaccharide deacetylase (BAS5051), as factors contributing to SCWP synthesis. Here, we show that
tagO
(BAS5050), which encodes a UDP-
N
-acetylglucosamine:undecaprenyl-P
N
-acetylglucosaminyl 1-P transferase, the enzyme that initiates the synthesis of murein linkage units, is required for
B. anthracis
SCWP synthesis and S-layer assembly. Similar to
gneY-gneZ
mutants,
B. anthracis
strains lacking
tagO
cannot maintain cell shape or support vegetative growth. In contrast, mutations in BAS5051 do not affect
B. anthracis
cell shape, vegetative growth, SCWP synthesis, or S-layer assembly. These data suggest that TagO-mediated murein linkage unit assembly supports SCWP synthesis and attachment to the peptidoglycan via acid-labile phosphodiester bonds. Further,
B. anthracis
variants unable to synthesize SCWP trisaccharide repeats cannot sustain cell shape and vegetative growth.

IMPORTANCE
Bacillus anthracis
elaborates an SCWP to support vegetative growth and envelope assembly. Here, we show that some, but not all, SCWP synthesis is dependent on
tagO
-derived murein linkage units and subsequent attachment of SCWP to peptidoglycan. The data implicate secondary polymer modifications of peptidoglycan and subcellular distributions as a key feature of the cell cycle in Gram-positive bacteria and establish foundations for work on the molecular functions of the SCWP and on inhibitors with antibiotic attributes.
NagR Differentially Regulates the Expression of the
glmS
and
nagAB
Genes Required for Amino Sugar Metabolism by Streptococcus mutans
Authors: Zeng Lin , Burne Robert A.
Published: September 2015

The ability of bacteria to metabolize glucosamine (GlcN) and
N
-acetyl-
d
-glucosamine (GlcNAc) is considered important for persistent colonization of the oral cavity. In the dental caries pathogen
Streptococcus mutans
, the NagR protein regulates the expression of
glmS
, which encodes a GlcN-6-P synthetase, and
nagA
(GlcNAc-6-P deacetylase) and
nagB
(GlcN-6-P deaminase), which are required for the catabolism of GlcNAc and GlcN. Two NagR-binding sites (
dre
) were identified in each of the promoter regions for
nagB
and
glmS
. Using promoter-reporter gene fusions, the role of each
dre
site was examined in the regulation of
glmS
and
nagB
promoter activities in cells grown with glucose, GlcNAc, or GlcN. A synergistic relationship between the two
dre
sites in the
glmS
promoter that required proper spacing was observed, but that was not the case for
nagB
. Binding of purified NagR to DNA fragments from both promoter regions, as well as to
dre
sites alone, was strongly influenced by particular sugar phosphates. Using a random mutagenesis approach that targeted the effector-binding domain of NagR, mutants that displayed aberrant regulation of both the
glmS
and
nagAB
genes were identified. Collectively, these findings provide evidence that NagR is essential for regulation of genes for both the synthesis and catabolism of GlcN and GlcNAc in
S. mutans
, and that NagR engages differently with the target promoter regions in response to specific metabolites interacting with the effector-binding domain of NagR.

IMPORTANCE
Glucosamine and
N
-acetylglucosamine are among the most abundant naturally occurring sugars on the planet, and they are catabolized by many bacterial species as sources of carbon and nitrogen. Representing a group called lactic acid bacteria (LAB), the human dental caries pathogen
Streptococcus mutans
is shown to differ from known paradigm organisms in that it possesses a GntR/HutC-type regulator, NagR, that is required for the regulation of both catabolism of GlcN and biosynthesis. Results reported here reveal a simple and elegant mechanism whereby NagR differentially regulates two opposing biological processes by surveying metabolic intermediates. This study provides insights that may contribute to the development of novel therapeutic tools to combat dental caries and other infectious diseases.
Crossing boundaries and building bridges: integrative zoology
Authors: Shamchuk Angela L. , MacMillan Heath A.
Published: September 2015

The invited papers in this special issue highlight contributions to the symposium with the same title, held at Genomes to Biomes: the First Joint Meeting of the Canadian Society for Ecology and Evolution, the Canadian Society of Zoologists, and the Society of Canadian Limnologists. Today, leading researchers cross boundaries between layers of biological organization and traditional areas of expertise, and increasingly reach beyond their historical role in society to serve as public educators and science advocates. This series includes reviews of the integrative study of animals ranging from the very small (the world’s southernmost insect) to the very large (rorqual whales), a review on using ancient DNA to elucidate the physiology of long-extinct animals, and research articles that take us from the proteomic response of honey bees to Israeli acute paralysis virus (IAPV) infection to the geographic spread of a harmful invasive earthworm in the boreal forest.
INSTITUTIONS, INVESTMENT AND ECONOMIC GROWTH: A CROSS-COUNTRY AND PANEL DATA STUDY
Authors: NASREEN SAMIA , ANWAR SOFIA , WAQAR MASOOD QADIR
Published: September 2015

In this study, both cross-country and panel techniques have been used to analyze the long-term impact of institutions on investment and economic growth in the context of neoclassical model. The empirical results indicate that both physical and human capital investment have positive impact on economic growth. Economic freedom has a direct impact on economic growth by enhancing factor productivity and indirect by increasing investment. Political and civil liberties also exert positive impact on investment. Further, an important relationship exists between institutional freedom and human capital investment in both cross-country and panel data analysis.
INEQUALITY, FDI AND ECONOMIC DEVELOPMENT: EVIDENCE FROM DEVELOPING COUNTRIES
Authors: MAJEED MUHAMMAD TARIQ
Published: September 2015

This paper empirically investigates the impact of Foreign Direct Investment (FDI) on inequality using a panel data set of 65 developing counties. While the existing literature mainly examines the impact of FDI on growth, this study explores the importance of domestic conditions of the host countries in determining the distributional effects of FDI. The results show that the impact of FDI is not homogenous on host countries as FDI inflows exert inequality-narrowing effect only in countries that have stronger investment in human capital, better financial sector and a high level of economic development. While FDI accentuates not ameliorates inequality in countries with low level of economic development, findings of the study are robust to the use of different specifications, different estimation methods, inclusion of regional effects and time specific effects.
DETERMINANTS OF FEMALE FERTILITY IN ASEAN-5: EMPIRICAL EVIDENCE FROM BOUNDS COINTEGRATION TEST
Authors: SUBRAMANIAM THIRUNAUKARASU , LOGANATHAN NANTHAKUMAR , DEVADASON EVELYN S.
Published: September 2015

The ASEAN countries have been experiencing drastic declines in fertility of more than 10 percent, particularly since the 1990s. Though the literature on fertility has clearly delineated the importance of income, female labor force participation and infant mortality as key determinants of fertility rates (FRs), the empirical findings from previous studies remains at best mixed. This study therefore identifies the determinants of female fertility for the countries, namely Indonesia, Malaysia, Philippines, Singapore and Thailand (ASEAN-5 countries), spanning the period 1980–2010. Using the Autoregressive Distributed Lag (ARDL) cointegration and causality techniques, the main findings of the study are summarized as follows: First, a long-run (LR) stable relationship is evident between female fertility, female labor force participation, income and infant mortality for ASEAN-5. Second, there is a deviation of FRs from the short-run (SR) to the LR equilibrium for ASEAN-5, with the highest and lowest speed of adjustment recorded for Malaysia and Thailand, respectively. Third, FR and economic stability are found to be complementary in the LR for ASEAN-5. When the joint LR and SR causalities are considered, we found that female labor force participation, income and infant mortality have dynamic relationships with FR for all the five ASEAN countries.
Theoretical studies of the anisotropic g factors for deoxygenated Y123
Authors: Zhang L. J. , Wu S. Y. , Ding C. C. , Cheng Y. K.
Published: September 2015

The anisotropic [Formula: see text] factors of the deoxygenated YBaCuO (Y123) are theoretically studied using the perturbation formulas of the [Formula: see text] factors for a tetragonally elongated octahedral [Formula: see text] cluster. The ligand orbital and spin-orbit coupling contributions are included from the cluster approach in view of covalency. The calculated [Formula: see text] factors show good agreement with the experimental data. The anisotropy of the [Formula: see text] factors is analyzed by considering the local tetragonal elongation distortion around this five-fold coordinated [Formula: see text] site in the deoxygenated Y123 system.
The crossover from metal to semi-conductor in Cu-doped LiFeAs system
Authors: Xing L. Y. , Wang X. C. , Deng Z. , Zhang S. J. , Feng S. M. , Li W. M. , Liu Q. Q. , Jin C. Q.
Published: September 2015

A series of [Formula: see text] single crystal with the doping level [Formula: see text] were grown. The resistivity measurement was conducted. The results show that the 10% Cu doping completely suppresses superconducting transition temperature and when the doping level increases to 16%, it presents a semiconducting behavior in the region of 2 K to 300 K.
Stable local structure in LSMCO system and its relationship with pseudogap
Authors: Guo C. Q. , Yan Y. , Li L. , Han J. X. , Wei K. , Lin F. , Zhang H.
Published: September 2015

Pseudogap is a unique property of high-[Formula: see text] superconductors. However, it was also found that there is a similar pseudogap in giant magnetoresistive La–Sr–Mn–O materials, which are not superconductors. In our previous research, we suggested that the origin of the pseudogap is correlated with the stability of [Formula: see text] plane. We call it a steady “fixed triangle” local structure. If our assumption is correct, it will be expected to find a similar stable local structure in the La–Sr–Mn–O system, which is similar to the [Formula: see text] plane in cuprates. We synthesized Co-doped [Formula: see text] (LSMCO) materials and investigated them. Based on the detailed analysis of the crystalline structure, it is found that there indeed exists a stable local triangles in [Formula: see text] plane. Comparing this similarity with the fixed triangles in the cuprate superconductors, it shows that the origin of the pseudogap may possibly be correlated with the stability of the local structure.
Adaptive isogeometric methods with hierarchical splines: Error estimator and convergence
Authors: Buffa Annalisa , Giannelli Carlotta
Published: September 2015

The problem of developing an adaptive isogeometric method (AIGM) for solving elliptic second-order partial differential equations with truncated hierarchical B-splines of arbitrary degree and different order of continuity is addressed. The adaptivity analysis holds in any space dimensions. We consider a simple residual-type error estimator for which we provide a posteriori upper and lower bound in terms of local error indicators, taking also into account the critical role of oscillations as in a standard adaptive finite element setting. The error estimates are properly combined with a simple marking strategy to define a sequence of admissible locally refined meshes and corresponding approximate solutions. The design of a refine module that preserves the admissibility of the hierarchical mesh configuration between two consecutive steps of the adaptive loop is presented. The contraction property of the quasi-error, given by the sum of the energy error and the scaled error estimator, leads to the convergence proof of the AIGM.
On a generalized doubly parabolic Keller–Segel system in one spatial dimension
Authors: Burczak Jan , Granero-Belinchón Rafael
Published: September 2015

We study a doubly parabolic Keller–Segel system in one spatial dimension, with diffusions given by fractional Laplacians. We obtain several local and global well-posedness results for the subcritical and critical cases (for the latter we need certain smallness assumptions). We also study dynamical properties of the system with added logistic term. Then, this model exhibits a spatio-temporal chaotic behavior, where a number of peaks emerge. In particular, we prove the existence of an attractor and provide an upper bound on the number of peaks that the solution may develop. Finally, we perform a numerical analysis suggesting that there is a finite time blowup if the diffusion is weak enough, even in presence of a damping logistic term. Our results generalize on one hand the results for local diffusions, on the other the results for the parabolic–elliptic fractional case.