bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite Element Modeling and Experimental Characterization of Enhanced Hybrid Composite Structures for Improved Crashworthiness
Authors: Arronche Luciana , Martínez Israel , La Saponara Valeria , Ledesma Elias
Published: January 2013

In this work, two hybrid composite structures were designed, modeled, and tested for improved resistance to impact. They were inspired by bistable composite structures, which are structures composed of two parts: a so-called “main link” and a so-called “waiting link.” These links work together as a mechanism that will provide enhanced damage tolerance, and the structure exhibits a bistable stress/strain curve under static tension. The function of the main link is to break early, at which point the waiting link becomes active and provides a redundant load path. The goal of the current study was to design, manufacture, and test a similar concept for impact loading and achieve greatly improved impact resistance per unit weight. In the current project, the main link was designed to be a brittle composite material (in this case, woven carbon/epoxy) exposed to impact, while the waiting link was chosen to be made with a highly nonlinear and strong composite material (in this case, polyethylene/epoxy), on the opposite surface. Hence, the structure, if proven successful, can be considered an enhanced hybrid concept. An explicit finite element (FE) commercial code, LS-DYNA, was used to design and analyze the baseline as well as two proposed designs. The simulations' methodology was validated with results published in the literature, which reported tests from linear fiber-reinforced composites. The plots were obtained via the ASCII files generated from the FE code, processed using matlab®, and compared to experimental impact tests. An instrumented drop-weight testing machine performed impact tests, and a high-speed camera validated the specimens' displacement under impact. It is shown that the FE model provided qualitative behavior very consistent with the experiments but requires further improvements. Experimentally, it is shown that one of the two enhanced hybrid models leads to up to a 30% increase of returned energy/weight when compared to its baseline and, therefore, is worthy of further investigations.
Ultrasonic Doppler Velocimetry Measurement of Flow and Instabilities in a Rotating Lid-Driven Cylinder
Authors: Kong Zhao C. , Eddy Duncan O. , Martin Nathan K. , Houchens Brent C.
Published: January 2013

The steady, axisymmetric base flow and instabilities in a rotating lid-driven cylinder are investigated experimentally via ultrasonic Doppler velocimetry and verified with computations. The flow is governed by two parameters: the Reynolds number (based on the angular velocity of the top lid, the cylinder radius, and kinematic viscosity) and the aspect ratio (cylinder height/radius). Base states and instabilities are explored using ultrasonic Doppler velocimetry in two mixtures of glycerol and water. Velocity profiles in the cylinder are constructed for aspect ratio 2.5 and Reynolds numbers between 1000 and 3000. The results are compared to computational spectral element simulations, as well as previously published findings. The base flow velocity profiles measured by ultrasonic Doppler velocimetry are in good agreement with the numerical results below the critical Reynolds number. The same is true for time-averaged results above the critical Reynolds number. Prediction of the first axisymmetric instability is demonstrated, although not always at the expected critical Reynolds number. Advantages and limitations of ultrasonic Doppler velocimetry are discussed.
Numerical Modeling of the Nonlinear Elastic Response of Filled Elastomers via Composite-Sphere Assemblages
Authors: Goudarzi Taha , Lopez-Pamies Oscar
Published: January 2013

This paper proposes an effective numerical method to generate approximate solutions for the overall nonlinear elastic response of isotropic filled elastomers subjected to arbitrarily large deformations. The basic idea is first to idealize the random microstructure of isotropic filled elastomers as an assemblage of composite spheres and then to generate statically admissible numerical solutions, via finite elements, for these material systems directly in terms of the response of a single composite sphere subjected to affine stress boundary conditions. The key theoretical strengths of the method are discussed, and its accuracy and numerical efficiency assessed by comparisons with corresponding 3D full-field simulations. The paper concludes with a discussion of straightforward extensions of the proposed method to account for general classes of anisotropic microstructures and filler-elastomer interphasial phenomena, features of key importance in emerging advanced applications.
Biaxial Tension of Fibrous Tissue: Using Finite Element Methods to Address Experimental Challenges Arising From Boundary Conditions and Anisotropy
Authors: Jacobs Nathan T. , Cortes Daniel H. , Vresilovic Edward J. , Elliott Dawn M.
Published: January 2013

Planar biaxial tension remains a critical loading modality for fibrous soft tissue and is widely used to characterize tissue mechanical response, evaluate treatments, develop constitutive formulas, and obtain material properties for use in finite element studies. Although the application of tension on all edges of the test specimen represents the in situ environment, there remains a need to address the interpretation of experimental results. Unlike uniaxial tension, in biaxial tension the applied forces at the loading clamps do not transmit fully to the region of interest (ROI), which may lead to improper material characterization if not accounted for. In this study, we reviewed the tensile biaxial literature over the last ten years, noting experimental and analysis challenges. In response to these challenges, we used finite element simulations to quantify load transmission from the clamps to the ROI in biaxial tension and to formulate a correction factor that can be used to determine ROI stresses. Additionally, the impact of sample geometry, material anisotropy, and tissue orientation on the correction factor were determined. Large stress concentrations were evident in both square and cruciform geometries and for all levels of anisotropy. In general, stress concentrations were greater for the square geometry than the cruciform geometry. For both square and cruciform geometries, materials with fibers aligned parallel to the loading axes reduced stress concentrations compared to the isotropic tissue, resulting in more of the applied load being transferred to the ROI. In contrast, fiber-reinforced specimens oriented such that the fibers aligned at an angle to the loading axes produced very large stress concentrations across the clamps and shielding in the ROI. A correction factor technique was introduced that can be used to calculate the stresses in the ROI from the measured experimental loads at the clamps. Application of a correction factor to experimental biaxial results may lead to more accurate representation of the mechanical response of fibrous soft tissue.
Subject-Specific Inverse Dynamics of the Head and Cervical Spine During in Vivo Dynamic Flexion-Extension
Authors: Anderst William J. , Donaldson William F. , Lee Joon Y. , Kang James D.
Published: January 2013

The effects of degeneration and surgery on cervical spine mechanics are commonly evaluated through in vitro testing and finite element models derived from these tests. The objectives of the current study were to estimate the load applied to the C2 vertebra during in vivo functional flexion-extension and to evaluate the effects of anterior cervical arthrodesis on spine kinetics. Spine and head kinematics from 16 subjects (six arthrodesis patients and ten asymptomatic controls) were determined during functional flexion-extension using dynamic stereo X-ray and conventional reflective markers. Subject-specific inverse dynamics models, including three flexor muscles and four extensor muscles attached to the skull, estimated the force applied to C2. Total force applied to C2 was not significantly different between arthrodesis and control groups at any 10 deg increment of head flexion-extension (all p values ≥ 0.937). Forces applied to C2 were smallest in the neutral position, increased slowly with flexion, and increased rapidly with extension. Muscle moment arms changed significantly during flexion-extension, and were dependent upon the direction of head motion. The results suggest that in vitro protocols and finite element models that apply constant loads to C2 do not accurately represent in vivo cervical spine kinetics.
In Vitro Pulsatility Analysis of Axial-Flow and Centrifugal-Flow Left Ventricular Assist Devices
Authors: Stanfield J. Ryan , Selzman Craig H.
Published: January 2013

Recently, continuous-flow ventricular assist devices (CF-VADs) have supplanted older, pulsatile-flow pumps, for treating patients with advanced heart failure. Despite the excellent results of the newer generation devices, the effects of long-term loss of pulsatility remain unknown. The aim of this study is to compare the ability of both axial and centrifugal continuous-flow pumps to intrinsically modify pulsatility when placed under physiologically diverse conditions. Four VADs, two axial- and two centrifugal-flow, were evaluated on a mock circulatory flow system. Each VAD was operated at a constant impeller speed over three hypothetical cardiac conditions: normo-tensive, hypertensive, and hypotensive. Pulsatility index (PI) was compared for each device under each condition. Centrifugal-flow devices had a higher PI than that of axial-flow pumps. Under normo-tension, flow PI was 0.98 ± 0.03 and 1.50 ± 0.02 for the axial and centrifugal groups, respectively (p < 0.01). Under hypertension, flow PI was 1.90 ± 0.16 and 4.21 ± 0.29 for the axial and centrifugal pumps, respectively (p = 0.01). Under hypotension, PI was 0.73 ± 0.02 and 0.78 ± 0.02 for the axial and centrifugal groups, respectively (p = 0.13). All tested CF-VADs were capable of maintaining some pulsatile-flow when connected in parallel with our mock ventricle. We conclude that centrifugal-flow devices outperform the axial pumps from the basis of PI under tested conditions.
Synthetic array processing of ocean ambient noise for higher resolution seabed bottom loss estimation
Authors: Siderius Martin , Muzi Lanfranco , Harrison Chris H. , Nielsen Peter L.
Published: January 2013

Predicting transmission loss in the ocean often strongly depends on the bottom loss. Bottom loss can be estimated using ocean noise and vertical array beam-forming [Harrison and Simons, J. Acoust. Soc. Am. 112, 1377–1389 (2002)]. With finite length arrays, the bottom loss estimate using this method can be smoothed due to beam widths. This paper describes how the noise coherence function can be synthetically expanded, which is similar to extending the length of an array. A full wave ocean noise model is used to demonstrate, in simulation, how this leads to improvements in the resolution of bottom loss estimates.
A comparison of two methods for phase response calibration of hydrophones in the frequency range 10–400 kHz
Authors: Hayman Gary , Wang Yuebing , Robinson Stephen
Published: January 2013

A comparison is made of two methods for determining the phase response of hydrophones in the kilohertz frequency range: The three-transducer spherical-wave reciprocity method and the method of optical interferometry. The implementation of the methods and the corresponding experimental systems are described. To facilitate a comparison, the methods are used to determine the phase response of three commercially available measuring hydrophones over the frequency range from 10 to 400 kHz. The results are compared, showing agreement within the estimated uncertainties of the methods. An investigation is conducted into the sources of uncertainties in the methods which increase with frequency. The major sources of uncertainty are residual positioning errors giving rise to phase uncertainties; a significant problem for the reciprocity method is that it requires one hydrophone to be rotated during the measurement procedure. An additional source of uncertainty at higher frequencies may be present if the position of the sensing element is not central within the outer hydrophone boot.
Science Signaling
Podcast: 29 January 2013
Authors: Meier Friedegund , VanHook Annalisa M.
Published: January 2013

Vemurafenib induces endoplasmic reticulum stress in melanoma cells.
AM and FM Tuning of ERK Signaling
Authors: Gough Nancy R.
Published: January 2013

Like a radio, the mitogen-activated protein kinase pathway exhibits both frequency and amplitude modulation.
Complete Sequence of the IncT-Type Plasmid pT-OXA-181 Carrying the
bla
OXA-181
Carbapenemase Gene from Citrobacter freundii
Authors: Villa Laura , Carattoli Alessandra , Nordmann Patrice , Carta Claudio , Poirel Laurent
Published: January 2013

The gene encoding the carbapenemase OXA-181 (an OXA-48 variant) was identified from a
Citrobacter freundii
isolate coproducing NDM-1. The whole sequence of plasmid pT-OXA-181 bearing the
bla
OXA-181
gene was determined and revealed a 84-kb mobilizable but non-self-conjugative IncT-type plasmid. It totally differs from the 7.6-kb ColE-type and
bla
OXA-181
-bearing plasmid recently identified in a
Klebsiella pneumoniae
isolate. However, in both plasmids, insertion sequence IS
Ecp1
might have played a role in acquisition of the
bla
OXA-181
gene.
Outbreak of NDM-1-Producing Klebsiella pneumoniae in a Neonatal Unit in Colombia
Authors: Escobar Pérez Javier Antonio , Olarte Escobar Narda María , Castro-Cardozo Betsy , Valderrama Márquez Ismael Alberto , Garzón Aguilar Martha Isabel , Martinez de la Barrera Leslie , Barrero Barreto Esther Rocio , Marquez-Ortiz Ricaurte Alejandro , Moncada Guayazán Maria Victoria , Vanegas Gómez Natasha
Published: January 2013

Six multiresistant, NDM-1-producing
Klebsiella pneumoniae
strains were recovered from an outbreak that affected six neonatal patients in a Colombian hospital. Molecular analysis showed that all of the isolates harbored the
bla
NDM-1
,
qnrA
, and
intI1
genes and were clonally related. Multilocus sequence typing showed that the isolates belonged to a new sequence type (ST1043) that was different from the sequence types that had previously been reported. This is the first report of NDM-1-producing isolates in South America.
A Physiologically Based Pharmacokinetic Model of Rifampin in Mice
Authors: Lyons Michael A. , Reisfeld Brad , Yang Raymond S. H. , Lenaerts Anne J.
Published: January 2013

One problem associated with regimen-based development of antituberculosis (anti-TB) drugs is the difficulty of a systematic and thorough
in vivo
evaluation of the large number of possible regimens that arise from consideration of multiple drugs tested together. A mathematical model capable of simulating the pharmacokinetics and pharmacodynamics of experimental combination chemotherapy of TB offers a way to mitigate this problem by extending the use of available data to investigate regimens that are not initially tested. In order to increase the available mathematical tools needed to support such a model for preclinical anti-TB drug development, we constructed a preliminary whole-body physiologically based pharmacokinetic (PBPK) model of rifampin in mice, using data from the literature. Interindividual variability was approximated using Monte Carlo (MC) simulation with assigned probability distributions for the model parameters. An MC sensitivity analysis was also performed to determine correlations between model parameters and plasma concentration to inform future model development. Model predictions for rifampin concentrations in plasma, liver, kidneys, and lungs, following oral administration, were generally in agreement with published experimental data from multiple studies. Sensitive model parameters included those descriptive of oral absorption, total clearance, and partitioning of rifampin between blood and muscle. This PBPK model can serve as a starting point for the integration of rifampin pharmacokinetics in mice into a larger mathematical framework, including the immune response to
Mycobacterium tuberculosis
infection, and pharmacokinetic models for other anti-TB drugs.
A Novel Mechanism Underlies the Hepatotoxicity of Pyrazinamide
Authors: Shih Tung-Yuan , Pai Chien-Yi , Yang Ping , Chang Wen-Liang , Wang Ning-Chi , Hu Oliver Yoa-Pu
Published: January 2013

Relatively little is known about the hepatotoxicity of pyrazinamide (PZA). PZA requires activation by amidase to form pyrazinoic acid (PA). Xanthine oxidase then hydroxylates PA to form 5-hydroxypyrazinoic acid (5-OH-PA). PZA can also be directly oxidized to form 5-OH-PZA. Before this study, it was unclear which metabolic pathway or PZA metabolites led to hepatotoxicity. This study determines whether PZA metabolites are responsible for PZA-induced hepatotoxicity. PZA metabolites were identified and cytotoxicity in HepG2 cells was assessed. Potential PZA and PA hepatotoxicity was then tested in rats. Urine specimens were collected from 153 tuberculosis (TB) patients, and the results were evaluated to confirm whether a correlation existed between PZA metabolite concentrations and hepatotoxicity. This led to the hypothesis that coadministration of amidase inhibitor (bis-
p
-nitrophenyl phosphate [BNPP]) decreases or prevents PZA- and PZA metabolite-induced hepatotoxicity in rats. PA and 5-OH-PA are more toxic than PZA. Electron microscopy showed that PZA and PA treatment of rats significantly increases aspartate transaminase (AST) and alanine aminotransferase (ALT) activity and galactose single-point (GSP) levels (
P
< 0.005). PA and 5-OH-PA levels are also significantly correlated with hepatotoxicity in the urine of TB patients (
P
< 0.005). Amidase inhibitor, BNPP, decreases PZA-induced, but not PA-induced, hepatotoxicity. This is the first report of a cell line, animal, and clinical trial confirming that the metabolite 5-OH-PA is responsible for PZA-induced hepatotoxicity.
Pathogenicity of Yersinia pestis Synthesis of 1-Dephosphorylated Lipid A
Authors: Sun Wei , Six David A. , Reynolds C. Michael , Chung Hak Suk , Raetz Christian R. H. , Curtiss Roy
Published: January 2013

Synthesis of
Escherichia coli
LpxL, which transfers a secondary laurate chain to the 2′ position of lipid A, in
Yersinia pestis
produced bisphosphoryl hexa-acylated lipid A at 37°C, leading to significant attenuation of virulence. Our previous observations also indicated that strain χ10015(pCD1Ap) (Δ
lpxP32
::P
lpxL
lpxL
) stimulated a strong inflammatory reaction but sickened mice before recovery and retained virulence via intranasal (i.n.) infection. The development of live, attenuated
Y. pestis
vaccines may be facilitated by detoxification of its lipopolysaccharide (LPS). Heterologous expression of the lipid A 1-phosphatase, LpxE, from
Francisella tularensis
in
Y. pestis
yields predominantly 1-dephosphorylated lipid A, as confirmed by mass spectrometry. Results indicated that expression of LpxE on top of LpxL provided no significant reduction in virulence of
Y. pestis
in mice when it was administered i.n. but actually reduced the 50% lethal dose (LD
50
) by 3 orders of magnitude when the strain was administered subcutaneously (s.c.). Additionally, LpxE synthesis in wild-type
Y. pestis
KIM6+(pCD1Ap) led to slight attenuation by s.c. inoculation but no virulence change by i.n. inoculation in mice. In contrast to
Salmonella enterica
, expression of LpxE does not attenuate the virulence of
Y. pestis
.
RfaL Is Required for Yersinia pestis Type III Secretion and Virulence
Authors: Houppert Andrew S. , Bohman Lesley , Merritt Peter M. , Cole Christopher B. , Caulfield Adam J. , Lathem Wyndham W. , Marketon Melanie M.
Published: January 2013

Yersinia pestis
, the causative agent of plague, uses a type III secretion system (T3SS) to inject cytotoxic Yop proteins directly into the cytosol of mammalian host cells. The T3SS can also be activated
in vitro
at 37°C in the absence of calcium. The chromosomal gene
rfaL
(
waaL
) was recently identified as a virulence factor required for proper function of the T3SS. RfaL functions as a ligase that adds the terminal
N
-acetylglucosamine to the lipooligosaccharide core of
Y. pestis
. We previously showed that deletion of
rfaL
prevents secretion of Yops
in vitro
. Here we show that the divalent cations calcium, strontium, and magnesium can partially or fully rescue Yop secretion
in vitro
, indicating that the secretion phenotype of the
rfaL
mutant may be due to structural changes in the outer membrane and the corresponding feedback inhibition on the T3SS. In support of this, we found that the defect can be overcome by deleting the regulatory gene
lcrQ
. Consistent with a defective T3SS, the
rfaL
mutant is less virulent than the wild type. We show here that the virulence defect of the mutant correlates with a decrease in both T3SS gene expression and ability to inject innate immune cells, combined with an increased sensitivity to cationic antimicrobial peptides.
Warfarin-induced skin necrosis diagnosed on clinical grounds and treated with maggot debridement therapy
Authors: Biscoe Anna Louise , Bedlow Alison
Published: January 2013

A patient with a history of deep vein thrombosis presented with painful bruising and blistering on his left leg 7–10 days after warfarin treatment. A complicated 2-month treatment followed, where vasculitis was originally diagnosed from histological findings before the final diagnosis of warfarin-induced skin necrosis (WISN) was made on clinical grounds. Warfarin was stopped, reversed and low molecular weight heparin started but, the lesions had progressed to full thickness necrosis. This was originally treated with conventional surgical debridement before introducing maggot debridement therapy (MDT) in an effort to try to salvage the limb.
Syphilis: an ancient foe with multiple faces
Authors: Galveia José Nuno , Travassos Ana Sofia , Proença Dídia , Proença Rui
Published: January 2013

Syphilis can have a multitude of different ophthalmological presentations. The authors present a case of a 59-year-old man, with complaints of bilateral blurred vision starting 6 months before. His best-corrected visual acuity was 20/20 in both eyes. Ophthalmological examination revealed bilateral superotemporal retinal oedema, extending to the superior macular region, with a white stippled discolouration of the corresponding retinal pigment epithelium. Laboratory work-up confirmed the diagnosis of syphilis. The patient was treated with penicillin G benzathine—2.4 million IU intramuscular weekly for 3 weeks. After treatment, a clinical improvement of the fundus lesions was observed along with a subjective improvement in visual function. Over a 12 month follow-up period, no recurrences have occurred.
Sequelae of dental trauma: the malformed tooth
Authors: Chaudhary Seema , Chaitra T R , Vijayran Manisha , Kulkarni Adwait Uday
Published: January 2013

Here, we report a case of 10-year-old boy who came with a complaint of missing upper front teeth and was also concerned about his aesthetics. Significant history of trauma was present in his toddler period. Diagnosis of malformed upper right central incisor (11) by radiological investigations was carried out. Surgery was performed and there was removal of the impacted malformed upper right central incisor (11). Healing was uneventful. The patient is under follow-up for aesthetic rehabilitation to be carried out.
Is endovascular therapy the right choice for treatment of functional compression of anomalous right coronary artery arising from left coronary sinus with interarterial course?
Authors: Vadivelu Ramalingam , Bagga Shiv
Published: January 2013

We report a case of successful percutaneous coronary intervention (PCI) for reversible ischaemia owing to an anomalous right coronary artery arising from the left coronary sinus with malignant interarterial course and not associated with obstructive coronary artery disease (CAD). PCI for treatment of functional compression of the ostioproximal intramural segment of the anomalous vessel, though described in the literature, is technically challenging, requiring appropriate hardware selection; the peculiar anatomical milieu, in the absence of atherosclerotic CAD, lends itself to an uncertain long-term outcome following endovascular therapy with stenting.
Therapeutic dilemma in a case of acute coronary syndrome (ACS)
Authors: Bhat Smitha , D'Souza Amith , Fernandes Divya , Rajan Gautam
Published: January 2013

An adult male labourer, a smoker and alcoholic was admitted to our hospital with a short history of fever, myalgia, breathlessness and oliguria. On examination he was icteric and hypotensive. Calf muscle tenderness was present. A provisional diagnosis of leptospirosis was made and he was started on treatment with crystalline penicillin. Blood pressure (BP) did not improve with fluids. Inotropes were started. The patient was taken for Slow Low Efficiency Daily Dialysis (SLEDD) during which he developed chest pain. ECG showed an anterolateral myocardial infarction (MI). He also complained of breathlessness and haemoptysis. Antiplatelets were withheld in view of thrombocytopaenia and haemoptysis; heparin could not be given because of the deranged coagulation parameters. The patient was managed symptomatically with nitrates. After the BP improved SLEDD was restarted. On day 3 of admission the patient became tachypnoeic and hypoxic, bilateral coarse crackles were present on auscultation. He was intubated and mechanically ventilated. Suctioning of endotracheal tube revealed fresh blood, and chest CT revealed alveolar haemorrhage. In spite of aggressive resuscitative measures, mechanical ventilation and antibiotics, the patient expired on the 12th day following admission.
Infective endocarditis developing serious multiple complications
Authors: Guler Selma , Sokmen Abdullah , Mese Bulent , Bozoglan Orhan
Published: January 2013

A 20-year-old female patient with no history of heart disease presented to the hospital with high fever, cough and sputum. On the third day of hospitalisation, left facial paralysis developed and cranial  revealed an infarct in the right frontoparietotemporal lobe. Transthoracic echocardiography revealed 1.5×2 cm-sized vegetation on the mitral valve and severe mitral regurgitation. On the 11th day of hospitalisation, multiple emboli were shown to be present in the left iliac artery. Since the patient had recurrent septic emboli despite 3 weeks of treatment, a surgical intervention was planned. The vegetation was removed and the mitral valve was replaced by mechanical prostheses. During the postoperative period, acute renal failure developed in the patient. The treatment was completed in 6 weeks with full recovery. This case confirms that infective endocarditis may present with various clinical situations, and that a high index of suspicion and surgical intervention, in addition to aggressive antibiotic therapy, is lifesaving.
Extraocular sebaceous carcinoma mimicking benign sebaceous cyst
Authors: Gavriilidis Paschalis , Barbanis Sotirios , Theodorou Vasiliki , Christoforidou Barbara
Published: January 2013

Extraocular sebaceous carcinoma (SC) is an exceptionally rare neoplasm and has been confused in the past with basal cell carcinoma showing sebaceous differentiation. However, in contrast to the latter tumour, SC can be an aggressive cancer. We describe the case of a 55-year-old man with a 3-year history of a 5×2 cm lesion on the posterior thoracic wall. It had increased in size during this period but was otherwise asymptomatic. There was no significant past medical history or lymphadenopathy. Nor was there a family history of malignancy. The lesion was totally excised. The histopathological report revealed SC. As this neoplasm may be associated with Muir-Torre syndrome, the patient was screened for underlying internal neoplasia. All haematological, biochemical and tumour markers, imaging and endoscopic examinations were normal. Since SC may appear before the development of internal malignancy, our patient was scheduled for follow-up visits every 3 months.
Angiographic warning of hemorrhagic transformation after stent retriever thrombectomy procedure
Authors: Vollman Andrew T , Bruno Charles A , Dumeer Shifali , Malone Hani , Meyers Philip M
Published: January 2013

This study reports cerebral angiographic findings observed after stent retriever thrombectomy that is suggestive of a higher risk of hemorrhagic transformation (HT). A woman aged 65–75 presented with a right middle cerebral artery syndrome confirmed by non-contrast CT brain scan. Endovascular revascularization using the Solitaire device was placed across the thromboembolic occlusion and thromboembolectomy was performed. Angiography showed complete recanalization of the left internal carotid artery, anterior and middle cerebral artery branches. Twelve hours following the procedure the patient had a hemorrhagic conversion of the ischemic infarct with significant mass effect causing herniation. Despite surgical intervention (hemicraniectomy) the patient died. The angiographic features following revascularization of the vessels distal to the occlusion showed subtle dilations which were visualized at the branch points of the vessels. This may be a warning sign of increased risk of HT.
CHIRAL ANOMALY OF MASSLESS FERMION AT FINITE TEMPERATURE AND CHEMICAL POTENTIAL
Authors: SHI SONG , SUN WEI-MIN , ZONG HONG-SHI
Published: January 2013

In this paper, using the imaginary-time temperature field theory, we discuss the possible modification of chiral anomaly of a massless fermion in (3+1)-dimensional QED (QED4) when the temperature and chemical potential effects are included. It is found that the chiral anomaly is independent of the temperature and chemical potential. Meanwhile, we also introduce the chemical potential corresponding to chiral charge, and find that it will induce a Chern–Simons-like term, which has similar C transformation properties (and opposite P transformation property) to the corresponding Chern–Simons term in (2+1)-dimensional QED (QED3). More importantly, we find that when the chemical potential corresponding to the fermion number is space-dependent, it will induce an extra anomaly term. It is expected that this can yield new physical effects.
A 5-BIT 500-MS/S FLASH ADC USING TIME-DOMAIN COMPARISON
Authors: MIN YOUNG-JAE , KIM HOON-KI , KIM CHULWOO , KIM SOO-WON , KIM GIL-SU
Published: January 2013

A 5-bit 500-MS/s time-domain flash ADC is presented. The proposed ADC consists of a reference resistor ladder, two voltage-to-time converter arrays, a time-domain comparator array and a digital encoder without sample-and-hold. In order to achieve low-power consumption with high conversion-speed and to enhance design reusability in terms of a highly digital implementation with more regular mask patterns, the time-domain comparison is devised in the flash ADC. The prototype has been implemented and fabricated in a standard 0.18 μm CMOS technology and occupies 0.132 mm2 without pads. The measured SNDR and SFDR up to the Nyquist frequency are 26.6 dB and 35.1 dB, respectively. And the peak DNL and INL are measured as 0.43 LSB and 0.58 LSB, respectively. The prototype consumes 8 mW with a 1.8-V supply voltage.
Design, Analysis and Verification of Real-Time Systems Based on Time Petri Net Refinement
Authors: Ding Zhijun , Jiang Changjun , Zhou Mengchu
Published: January 2013

A type of refinement operations of time Petri nets is presented for design, analysis and verification of complex real-time systems. First, the behavior preservation is studied under time constraints in a refinement operation, and a sufficient condition for behavior preservation is obtained. Then, the property preservation is considered, and the results indicate that if the refinement operation of time Petri nets satisfies behavior preservation, it can also preserve properties such as boundedness and liveness. Finally, based on the behavior preservation, a reachability decidability algorithm of a refined time Petri net is designed using the reachability trees of its original net and subnet. The research results are illustrated by an example of designing, analyzing and verifying a real-time manufacturing system.
Reducing Interleaving Semantics Redundancy in Reachability Analysis of Time Petri Nets
Authors: Boucheneb Hanifa , Barkaoui Kamel
Published: January 2013

The main problem of verification techniques based on exploration of (reachable) state space is the state explosion problem. In timed models, abstract states reached by different interleavings of the same set of transitions are, in general, different and their union is not necessarily an abstract state. To attenuate this state explosion, it would be interesting to reduce the redundancy caused by the interleaving semantics by agglomerating all these abstract states whenever their union is an abstract state.

This article considers the time Petri net model and establishes some sufficient conditions that ensure that this union is an abstract state. In addition, it proposes a procedure to compute this union without computing beforehand intermediate abstract states. Finally, it shows how to use this result to improve the reachability analysis.
A Hybrid Genetic Algorithm for the Bottleneck Traveling Salesman Problem
Authors: Ahmed Zakir Hussain
Published: January 2013

The bottleneck traveling salesman problem is to find a Hamiltonian circuit that minimizes the largest cost of any of its arcs in a graph. A simple genetic algorithm (GA) using sequential constructive crossover has been developed to obtain heuristic solution to the problem. The hybrid GA incorporates 2-opt search, another proposed local search and immigration to the simple GA for obtaining better solution. The efficiency of our hybrid GA to the problem against two existing heuristic algorithms has been examined for some symmetric TSPLIB instances. The comparative study shows the effectiveness of our hybrid algorithm. Finally, we present solutions to the problem for asymmetric TSPLIB instances.
One-Step Look-Ahead Maximally Permissive Deadlock Control of AMS by Using Petri Nets
Authors: Wu Naiqi , Zhou Mengchu , Hu Gang
Published: January 2013

It is desired that a deadlock control policy for automated manufacturing systems (AMS) is maximally permissive. However, its tractability issue remains open, and this work addresses this important issue. It models AMS with a resource-oriented Petri net (ROPN) and presents a necessary and sufficient condition under which there exists a one-step look-ahead maximally permissive control policy for deadlock avoidance in AMS. It further identifies some conditions under which a one-step look-ahead maximally permissive deadlock control policy exists for a single-capacity system. The conditions can be conveniently examined by using the developed ROPN model.
Transition-Based Deadlock Detection and Recovery Policy for FMSs Using Graph Technique
Authors: Huang Yi-Sheng , Pan Yen-Liang , Su Pin-June
Published: January 2013

A transition-controlled deadlock detection and recovery prevention policy is presented for a subclass of Petri nets used to model flexible manufacturing systems. The subclass is called systems of simple sequential processes with resources (S
3
PR). The proposed policy is different from the standard deadlock prevention policies. Instead of adding control places, this policy adds a controlled transition to solve a group of deadlocked markings that have the same graph-based property. Finally, the results of our study indicate that the proposed policy appears to be more permissive than those existing ones that add control places.
Fault Modeling in Discrete Event Systems Using Petri Nets
Authors: Nazemzadeh Payam , Dideban Abbas , Zareiee Meisam
Published: January 2013

In this article a model-based controller reconfiguration method for fault-tolerant control of discrete event systems has been introduced. In this method, we model the fault conditions for each specified fault as a new model called fault model. The system then consists of three different models called process, specification and fault. The faulty parts of the system are not permitted to do any job and the controller tries to enforce the specifications by other parts of the system. With this method, the controller reconfiguration problem for fault- tolerant control of discrete event systems converts to the problem of synchronizing the process, specification and fault model. We must synthesize a supervisor that can enforce both specifications and faults status. If this supervisor can be determined, we can achieve a fault-tolerant controller. Implementing both specification and fault models in the system, may lead to a large number of forbidden states and constraints and so on a more complicated forbidden states problem must be solved. The application of constraints simplification methods is shown. By the existing methods for offline simplifying of constraints, we can arrive at a simplified fault tolerant controller.
Formalization of Measure Theory and Lebesgue Integration for Probabilistic Analysis in HOL
Authors: Mhamdi Tarek , Hasan Osman , Tahar Sofiène
Published: January 2013

Dynamic systems that exhibit probabilistic behavior represent a large class of man-made systems such as communication networks, air traffic control, and other mission-critical systems. Evaluation of quantitative issues like performance and dependability of these systems is of paramount importance. In this paper, we propose a generalized methodology to formally reason about probabilistic systems within a theorem prover. We present a formalization of measure theory in the HOL theorem prover and use it to formalize basic concepts from the theory of probability. We also use the Lebesgue integration to formalize statistical properties of random variables. To illustrate the practical effectiveness of our methodology, we formally prove classical results from the theories of probability and information and use them in a data compression application in HOL.
Distributed Reconfigurations of Autonomous IEC61499 Systems
Authors: Khalgui Mohamed
Published: January 2013

The article deals with Distributed Multiagent Reconfigurable Embedded Control Systems following the International Industrial Standard IEC61499 in which a Function Block (Abbreviated by FB) is an event-triggered software component owning data and a control system is a network of distributed blocks. We define a multiagent embedded architecture in which a
Reconfiguration Agent
is affected to each device of the execution environment to apply local reconfigurations, and a
Coordination Agent
is proposed for coordination between devices in order to guarantee safe and coherent distributed reconfigurations. A Communication Protocol is proposed to handle such coordination by using well-defined
Coordination Matrices
. A prototype is developed to simulate the whole architecture when faults occur or system’s optimizations are applied. We specify Reconfiguration Agents to be modeled by nested state machines, and the Coordination Agent according to the formalism Net Condition/Event Systems (Abbreviated by NCES) which is an extension of Petri nets. To allow correct and coherent distributed reconfigurations, we check all possible interactions between controllers by verifying that whenever a reconfiguration is applied in a device, the Coordination Agent and other concerned devices react as described in user requirements. We propose finally XML-based implementations of both Coordination and Reconfiguration Agents according the the technology IEC61499. The article’s contributions are applied to two Benchmark Production Systems available in our research laboratory.
An information-theoretic measure to evaluate parsing difficulty across treebanks
Authors: Corazza Anna , Lavelli Alberto , Satta Giorgio
Published: January 2013

With the growing interest in statistical parsing, special attention has recently been devoted to the problem of comparing different treebanks to assess which languages or domains are more difficult to parse relative to a given model. A common methodology for comparing parsing difficulty across treebanks is based on the use of the standard labeled precision and recall measures. As an alternative, in this article we propose an information-theoretic measure, called the expected conditional cross-entropy (ECC). One important advantage with respect to standard performance measures is that ECC can be directly expressed as a function of the parameters of the model. We evaluate ECC across several treebanks for English, French, German, and Italian, and show that ECC is an effective measure of parsing difficulty, with an increase in ECC always accompanied by a degradation in parsing accuracy.
The tail at scale
Authors: Dean Jeffrey , Barroso Luiz André
Published: January 2013

Software techniques that tolerate latency variability are vital to building responsive large-scale Web services.
Java source-code clustering: Unifying syntactic and semantic features
Authors: Misra Janardan , KM Annervaz , Kaulgud Vikrant , Sengupta Shubhashis , Titus Gary
Published: January 2013

This is a report from an international workshop on "Social and Algorithmic Issues in Business Support" (SAIBS), which was organized in conjunction with the 16th ADBIS Conference in Poznan, Poland, on September 17, 2012. The main focus of this workshop was to provide a venue for the discussion whether social stands in opposition to
algorithmic or systematic
. We analyzed social contribution to business processes taking into account possible benefits and risk factors. Questions raised in collected research and discussion related to how far business could relay on social input and what were the limits or what were the areas where introducing crowdsourced components might increase overall risk value to unacceptable level? Algorithmic approach to observe and collect social behaviour was discussed in the context of internet auctions participants and car drivers equipped in mobile application for instant route planning and collecting feedback cartracking data. Having in mind Andrew Keen's critique of social contribution in Web 2.0-related phenomena we looked for the
Wisdom of Crowds
[1]. Collected conclusions and further dissemination of research results should lead to an improvement in utilizing social impact on software development and business processes.
Prevention of XSS attacks using STCD
Authors: Brahmasani Siva , Selvakumar Subramanian , Sivasankar E.
Published: January 2013

Variability (the ability of a software system or software artifact to be adapted for use in a specific context) is reflected in and facilitated through the software architecture. The Second International Workshop on Variability in Software Architecture (VARSA) was held in conjunction with the Joint 10th Working IEEE/IFIP Conference on Software Architecture & 6th European Conference on Software Architecture 2012 in Helsinki, Finland. The workshop aimed at exploring current and emerging methods, languages, notations technologies and tools to model, implement, and manage variability in the software architecture. It featured one industrial talk, five research paper presentations, and three working group discussions. Working groups discussed topics that emerged during the workshop. This report summarizes the themes of the workshop and presents the results of the working group discussions.
Software Licenses - A tool to control distribution of software
Authors: Sharma Vineet , Rizvi S. A.M. , Sharma Arun
Published: January 2013

The International Workshop on Developing Tools as Plug-Ins (TOPI) is a venue for researchers and practitioners interested in plug-in development. The main interest is understanding the opportunities and challenges of developing tools as plug-ins, and thus, we seek for discussions regarding the characteristics of good plug-ins, interoperability requirements to making tools available across platforms, recent successful tools as plug-ins as well as foreseen medium and long term challenges of tools as plug-ins. The second edition of this workshop, TOPI 2012 was co-located with the International Conference on Software Engineering (ICSE 2012). TOPI 2012 received a total of 32 submissions. Among them, 14 were accepted as full papers and 4 as short papers. The audience during the whole workshop ranged from 25 to 30 participants. The final program comprised position papers including new proposals for plug-in architectures as well as their interaction with development environments and run-times, and papers discussing the implementation of different kind of tools as plug-ins. This report describes the main results of TOPI 2012.
Bayesian Learning of Noisy Markov Decision Processes
Authors: Singh Sumeetpal S. , Chopin Nicolas , Whiteley Nick
Published: January 2013

We consider the inverse reinforcement learning problem, that is, the problem of learning from, and then predicting or mimicking a controller based on state/action data. We propose a statistical model for such data, derived from the structure of a Markov decision process. Adopting a Bayesian approach to inference, we show how latent variables of the model can be estimated, and how predictions about actions can be made, in a unified framework. A new Markov chain Monte Carlo (MCMC) sampler is devised for simulation from the posterior distribution. This step includes a parameter expansion step, which is shown to be essential for good convergence properties of the MCMC sampler. As an illustration, the method is applied to learning a human controller.
Small Variance Estimators for Rare Event Probabilities
Authors: Broniatowski Michel , Caron Virgile
Published: January 2013

Improving Importance Sampling estimators for rare event probabilities requires sharp approximations of conditional densities. This is achieved for events defined through large exceedances of the empirical mean of summands of a random walk, in the domain of large or moderate deviations. The approximation of conditional density of the trajectory of the random walk is handled on long runs. The length of those runs which is compatible with a given accuracy is discussed; simulated results are presented, which enlight the gain of the present approach over classical Importance Sampling schemes. Detailed algorithms are proposed.
A Three‐Dimensional Enormous Surface Area Aluminum Microneedle Array with Nanoporous Structure
Authors: Chen Po Chun , Hsieh Sheng Jen , Chen Chien Chon , Zou Jun
Published: January 2013

We proposed fabricating an aluminum microneedle array with a nanochannel structure on the surface by combining micromachining, electrolyte polishing, and anodization methods. The microneedle array provides a three‐dimensional (3D) structure that possesses several hundred times more surface area than a traditional nanochannel template. Therefore, the microneedle array can potentially be used in many technology applications. This 3D microneedle array device can not only be used for painless injection or extraction, but also for storage, highly sensitive detection, drug delivery, and microelectrodes. From the calculation we made, the microneedle array not only increases surface area, but also enlarges the capacity of the device. Therefore, the microneedle array can further be used on many detecting, storing, or drug delivering applications.
Review of the Early Diagnoses and Assessment of Rejection in Vascularized Composite Allotransplantation
Authors: Starzl Ravi , Brandacher Gerald , Lee W. P. Andrew , Carbonell Jaime , Zhang Wensheng , Schnider Jonas , Gorantla Vijay , Schneeberger Stefan , Zheng Xin Xiao
Published: January 2013

The emerging field of vascular composite allotransplantation (VCA) has become a clinical reality. Building upon cutting edge understandings of transplant surgery and immunology, complex grafts such as hands and faces can now be transplanted with success. Many of the challenges that have historically been limiting factors in transplantation, such as rejection and the morbidity of immunosuppression, remain challenges in VCA. Because of the accessibility of most VCA grafts, and the highly immunogenic nature of the skin in particular, VCA has become the focal point for cross-disciplinary approaches to developing novel approaches for some of the most challenging immunological problems in transplantation, particularly the early diagnoses and assessment of rejection. This paper provides a historically oriented introduction to the field of organ transplantation and the evolution of VCA.