bluuebunny/crossref_metadata_2025 huggingface dataset:
A Genetic Intervention Stands a Skip Away from Clinical Tests
Authors: Chamberlain Jeffrey S.
Published: December 2012

A drug that improves production of dystrophin protein reduces disease severity in a mouse model of Duchenne muscular dystrophy.
Mobilizing Scientific Societies
Authors: Alberts Bruce
Published: December 2012

In last week's Editorial, I lamented the superficial, skin-deep approach to science learning that is common in America's schools.
*
The situation has proven highly resistant to change, and it continues to have a disastrous, long-lasting effect on the attitudes of students toward science (millions of whom are now adults). The main culprit is the strong demand for a broad “coverage” of each subject, which kills student interest and makes genuine comprehension almost impossible. At the precollege level, this push is driven by state-based textbook adoption policies, by high-stakes examinations, and—inadvertently—by a scientific community that largely fails to understand teachers' needs. How might scientists be mobilized to support a much more inspiring, in-depth form of science education?
NIH Offers to Help Universities Improve Training, Boost Diversity
Authors: Kaiser Jocelyn
Published: December 2012

The National Institutes of Health has announced a plan to prepare scientists for a range of careers, move students through their Ph.D.s faster, and bolster the pay of postdocs. Officials say the changes are not aimed at reducing or even stabilizing the number of graduates but are intended to improve the training experience.
The Tale of the TALEs
Authors: Pennisi Elizabeth
Published: December 2012

Biologists have turned plant pest proteins into tools for studying and reshaping genomes of many species.
Comparison of Four Commercially Available Avidity Tests for Toxoplasma gondii-Specific IgG Antibodies
Authors: Villard O. , Breit L. , Cimon B. , Franck J. , Fricker-Hidalgo H. , Godineau N. , Houze S. , Paris L. , Pelloux H. , Villena I. , Candolfi E.
Published: December 2012

Toxoplasma
infection in pregnant women may cause congenital toxoplasmosis. Diagnosis of infection is based on serological tests aimed at detecting IgM and IgG antibodies against
Toxoplasma gondii
. However, IgM antibodies are not an accurate marker for discriminating between acute and latent infection. Detection of residual or persistent IgM may occur months or even years after primary infection, while the IgG avidity test is a rapid means of identifying latent infections in pregnant women who exhibit both IgG and IgM anti-
Toxoplasma
antibodies on initial testing during pregnancy. In this study, we assessed and compared the performances of four commercially available
Toxoplasma
IgG avidity tests in immunocompetent and immunocompromised patients with acute and latent toxoplasmosis. The positive predictive value of high avidity to confirm latent toxoplasmosis was 100% for all the assays, indicating that high avidity is a hallmark of latent infection. However, the negative predictive value of high avidity ranged from 99.2% (bioMérieux) to 95.3% (Abbott), indicating that acute toxoplasmosis could not be reliably diagnosed based on low IgG avidity alone. Thus, the avidity test provides a rapid means for identifying latent
Toxoplasma
infection in immunocompetent pregnant women presenting both IgG and IgM anti-
Toxoplasma
antibodies on initial testing. In terms of cost-effectiveness, avidity testing is a powerful tool that optimizes screening and follow-up of pregnant women while minimizing the costs of screening by avoiding subsequent costly maternal and fetal investigation and unnecessary treatment. The cheapest assay, Vidas Toxo IgG Avidity, also had the best performance for the diagnosis of latent toxoplasmosis.
Poor Immune Responses of Newborn Rhesus Macaques to Measles Virus DNA Vaccines Expressing the Hemagglutinin and Fusion Glycoproteins
Authors: Polack Fernando P. , Lydy Shari L. , Lee Sok-Hyong , Rota Paul A. , Bellini William J. , Adams Robert J. , Robinson Harriet L. , Griffin Diane E.
Published: December 2012

A vaccine that would protect young infants against measles could facilitate elimination efforts and decrease morbidity and mortality in developing countries. However, immaturity of the immune system is an important obstacle to the development of such a vaccine. In this study, DNA vaccines expressing the measles virus (MeV) hemagglutinin (H) protein or H and fusion (F) proteins, previously shown to protect juvenile macaques, were used to immunize groups of 4 newborn rhesus macaques. Monkeys were inoculated intradermally with 200 μg of each DNA at birth and at 10 months of age. As controls, 2 newborn macaques were similarly vaccinated with DNA encoding the influenza virus H5, and 4 received one dose of the current live attenuated MeV vaccine (LAV) intramuscularly. All monkeys were monitored for development of MeV-specific neutralizing and binding IgG antibody and cytotoxic T lymphocyte (CTL) responses. These responses were poor compared to the responses induced by LAV. At 18 months of age, all monkeys were challenged intratracheally with a wild-type strain of MeV. Monkeys that received the DNA vaccine encoding H and F, but not H alone, were primed for an MeV-specific CD8+CTL response but not for production of antibody. LAV-vaccinated monkeys were protected from rash and viremia, while DNA-vaccinated monkeys developed rashes, similar to control monkeys, but had 10-fold lower levels of viremia. We conclude that vaccination of infant macaques with DNA encoding MeV H and F provided only partial protection from MeV infection.
Gene Expression Profile and Immunological Evaluation of Unique Hypothetical Unknown Proteins of Mycobacterium leprae by Using Quantitative Real-Time PCR
Authors: Kim Hee Jin , Prithiviraj Kalyani , Groathouse Nathan , Brennan Patrick J. , Spencer John S.
Published: December 2012

The cell-mediated immunity (CMI)-based
in vitro
gamma interferon release assay (IGRA) of
Mycobacterium leprae
-specific antigens has potential as a promising diagnostic means to detect those individuals in the early stages of
M. leprae
infection. Diagnosis of leprosy is a major obstacle toward ultimate disease control and has been compromised in the past by the lack of specific markers. Comparative bioinformatic analysis among mycobacterial genomes identified potential
M. leprae
-specific proteins called “hypothetical unknowns.” Due to massive gene decay and the prevalence of pseudogenes, it is unclear whether any of these proteins are expressed or are immunologically relevant. In this study, we performed cDNA-based quantitative real-time PCR to investigate the expression status of 131 putative open reading frames (ORFs) encoding hypothetical unknowns. Twenty-six of the
M. leprae
-specific antigen candidates showed significant levels of gene expression compared to that of ESAT-6 (ML0049), which is an important T cell antigen of low abundance in
M. leprae
. Fifteen of 26 selected antigen candidates were expressed and purified in
Escherichia coli
. The seroreactivity to these proteins of pooled sera from lepromatous leprosy patients and cavitary tuberculosis patients revealed that 9 of 15 recombinant hypothetical unknowns elicited
M. leprae
-specific immune responses. These nine proteins may be good diagnostic reagents to improve both the sensitivity and specificity of detection of individuals with asymptomatic leprosy.
Adults 65 Years Old and Older Have Reduced Numbers of Functional Memory T Cells to Respiratory Syncytial Virus Fusion Protein
Authors: Cherukuri Anu , Patton Kathryn , Gasser Robert A. , Zuo Fengrong , Woo Jennifer , Esser Mark T. , Tang Roderick S.
Published: December 2012

Respiratory syncytial virus (RSV) infects elderly (≥65 years) adults, causing medically attended illness and hospitalizations. While RSV neutralizing antibody levels correlate inversely with RSV-associated hospitalization in the elderly, the role of RSV-specific T cells in preventing disease in the elderly remains unclear. We examined RSV-specific humoral, mucosal, and cellular immune profiles in healthy elderly (65 to 85 years) and young (20 to 30 years) adults. RSV neutralization antibody titers in the elderly (10.5 ± 2.2 log2) and young (10.5 ± 2.1 log2) were similar. In contrast, levels of RSV F protein-specific gamma interferon (IFN-γ)-producing T cells were lower in elderly (180 ± 80 spot-forming cells [SFC]/106peripheral blood mononuclear cells [PBMC]) than in young adults (1,250 ± 420 SFC/106PBMC). Higher levels of interleukin-13 (IL-13; 3,000 ± 1,000 pg/ml) in cultured PBMC supernatants and lower frequency of RSV F-specific CD107a+CD8+T cells (3.0% ± 1.6% versus 5.0% ± 1.6%) were measured in PBMC from elderly than young adults. These results suggest that deficient RSV F-specific T cell responses contribute to susceptibility to severe RSV disease in elderly adults.
Distinct HIV-1 Escape Patterns Selected by Cytotoxic T Cells with Identical Epitope Specificity
Authors: Yagita Yuichi , Kuse Nozomi , Kuroki Kimiko , Gatanaga Hiroyuki , Carlson Jonathan M. , Chikata Takayuki , Brumme Zabrina L. , Murakoshi Hayato , Akahoshi Tomohiro , Pfeifer Nico , Mallal Simon , John Mina , Ose Toyoyuki , Matsubara Haruki , Kanda Ryo , Fukunaga Yuko , Honda Kazutaka , Kawashima Yuka , Ariumi Yasuo , Oka Shinichi , Maenaka Katsumi , Takiguchi Masafumi
Published: December 2012

Pol283-8-specific, HLA-B*51:01-restricted, cytotoxic T cells (CTLs) play a critical role in the long-term control of HIV-1 infection. However, these CTLs select for the reverse transcriptase (RT) I135X escape mutation, which may be accumulating in circulating HIV-1 sequences. We investigated the selection of the I135X mutation by CTLs specific for the same epitope but restricted by HLA-B*52:01. We found that Pol283-8-specific, HLA-B*52:01-restricted CTLs were elicited predominantly in chronically HIV-1-infected individuals. These CTLs had a strong ability to suppress the replication of wild-type HIV-1, though this ability was weaker than that of HLA-B*51:01-restricted CTLs. The crystal structure of the HLA-B*52:01-Pol283-8 peptide complex provided clear evidence that HLA-B*52:01 presents the peptide similarly to HLA-B*51:01, ensuring the cross-presentation of this epitope by both alleles. Population level analyses revealed a strong association of HLA-B*51:01 with the I135T mutant and a relatively weaker association of HLA-B*52:01 with several I135X mutants in both Japanese and predominantly Caucasian cohorts. An
in vitro
viral suppression assay revealed that the HLA-B*52:01-restricted CTLs failed to suppress the replication of the I135X mutant viruses, indicating the selection of these mutants by the CTLs. These results suggest that the different pattern of I135X mutant selection may have resulted from the difference between these two CTLs in the ability to suppress HIV-1 replication.
Outer Domain of HIV-1 gp120: Antigenic Optimization, Structural Malleability, and Crystal Structure with Antibody VRC-PG04
Authors: Joyce M. Gordon , Kanekiyo Masaru , Xu Ling , Biertümpfel Christian , Boyington Jeffrey C. , Moquin Stephanie , Shi Wei , Wu Xueling , Yang Yongping , Yang Zhi-Yong , Zhang Baoshan , Zheng Anqi , Zhou Tongqing , Zhu Jiang , Mascola John R. , Kwong Peter D. , Nabel Gary J.
Published: December 2012

The outer domain of the HIV-1 gp120 envelope glycoprotein contains the epitope for broadly neutralizing antibodies directed to the CD4-binding site, many of which are able to neutralize over 90% of circulating HIV-1 isolates. While the outer domain is conformationally more stable than other portions of the HIV-1 envelope, efforts to express the outer domain as an immunogen for eliciting broadly neutralizing antibodies have not been successful, potentially because natural outer domain variants do not bind strongly to antibodies such as VRC01. In this study, we optimized the antigenic properties of the HIV-1 Env outer domain to generate OD4.2.2, from the KER2018 strain of clade A HIV-1, enabling it to bind antibodies such as VRC01 with nanomolar affinity. The crystal structure of OD4.2.2 in complex with VRC-PG04 was solved at 3.0-Å resolution and compared to known crystal structures including (i) the structure of core gp120 bound by VRC-PG04 and (ii) a circularly permutated version of the outer domain in complex with antibody PGT128. Much of the VRC-PG04 epitope was preserved in the OD4.2.2 structure, though with altered N and C termini conformations. Overall, roughly one-third of the outer domain structure appeared to be fixed in conformation, independent of alterations in termini, clade, or ligand, while other portions of the outer domain displayed substantial structural malleability. The crystal structure of OD4.2.2 with VRC-PG04 provides atomic-level details for an HIV-1 domain recognized by broadly neutralizing antibodies and insights relevant to the rational design of an immunogen that could elicit such antibodies by vaccination.
Pulmonary embolism mimicking left-ventricular hypertrophy on ECG
Authors: Tan Alan , Yikona Joseph
Published: December 2012

Patients with pulmonary embolism (PE) can show changes on the ECG. Here, we report the case of a 48-year-old man who initially presented with calf discomfort and swelling. He was discharged with no anticoagulation after a negative complex duplex venous ultrasonography for deep vein thrombosis (DVT). He presented 4 days later with shortness of breath and pleuritic chest pain. Multiple pulmonary emboli were found on CT pulmonary angiogram. His ECGs showed left-ventricular strain which is unusual for PE. He was anticoagulated and discharged. Despite presenting 2 days later with PE-related complications, he eventually recovered well.
Obstructive jaundice induced by biliary ascariasis
Authors: Keating Aine , Quigley James Aidan , Genterola Al Frederick
Published: December 2012

Ascaris lumbricoidesis one of the most prevalent parasitic infections, especially in developing countries. Its presence can lead to a multitude of presentations, one of the rarer ones being obstructive jaundice due to migration of the worm in to the biliary tree. We describe a case of a man who presented as an emergency to the general surgeons complaining of abdominal pain, fever, jaundice and vomiting. Ultrasound was used and the diagnosis of biliary ascariasis was made. The patient underwent surgery consisting of a cholecystectomy, common bile duct exploration and T-tube choledochostomy. Our report highlights the varied aetiology of obstructive jaundice and the importance of including biliary ascariasis in the differential diagnosis of the jaundiced patient, especially from endemic areas.
Acute liver injury associated with glucosamine dietary supplement
Authors: Ebrahim Vivian , Albeldawi Mazen , Chiang Dian Jung
Published: December 2012

A 55-year-old woman taking  over-the-counter (OTC) glucosamine developed symptomatic hepatotoxicity. Several of her liver enzymes were elevated to 10 times the upper limit of normal. One week after discontinuing glucosamine, serum transaminases fell dramatically, with some returning to normal limits.  Four weeks after glucosamine was discontinued, all her liver tests were normal. Rechallenge was not attempted. The potential causes of hepatocellular injury were evaluated. Glucosamine is a dietary supplement available in a wide variety of commercial preparations, primarily used for joint relief in osteoarthritis. Despite the extensive use of glucosamine supplements, significant elevations of transaminases are rare. The mechanism of hepatotoxicity in many OTC herbal preparations is unknown. It is vital for physicians to elicit a careful history of OTC medications and educate their patients on their potential adverse effects.
Schwannoma in anterior mediastinum with massive pericardial effusion
Authors: Vaish Arvind Kumar , Verma Sudhir Kumar , Shakya Shobhit , Goel Madhu Mati
Published: December 2012

Schwannoma is a benign nerve sheath neoplasm of schwann cell origin. Mediastinum is the second most common site of schwannoma with majority originating in the posterior medistinum. Mediastinal schwannoma is slow growing and mostly asymptomatic in presentation. We present a case of schwannoma arising in the anterior mediastinum, an unusual location, complicated by massive haemorrhagic pericardial effusion. We recommend an aggressive approach in such cases with pericardiectomy to prevent reaccumulation of the pericardial fluid.
Acute surgical management in idiopathic intracranial hypertension
Authors: Zakaria Zaitun , Fenton Eoin , Sattar Muhammad Taufiq
Published: December 2012

Idiopathic intracranial hypertension is a headache syndrome with progressive symptoms of raised intracranial pressure. Most commonly, it is a slow process where surveillance and medical management are the main treatment modalities. We describe herein an acute presentation with bilateral sixth nerve palsies, papilloedema and visual deterioration, where acute surgical intervention was a vision-saving operation.
Assessing variability in neurointerventional practice patterns for acute ischemic stroke
Authors: Mehta Brijesh , Leslie-Mazwi Thabele M , Chandra Ronil V , Chaudhry Zeshan A , Rabinov James D , Hirsch Joshua A , Schwamm Lee H , Rost Natalia S , Yoo Albert J
Published: December 2012

Background

Intra-arterial therapy (IAT) is increasingly used to treat patients with acute stroke with large vessel occlusions. There are minimal data and guidelines for treatment indications and performance standards. We aimed to gain a better understanding of real-world practice patterns for IAT.

Methods

An internet-based survey was launched to address six specific areas of IAT: practice setting, operator background, operational protocols, quality/safety, decision-making and treatment strategies. The survey invitation was distributed to members of multiple neurointerventional societies.

Results

Responses from 140 neurointerventionalists worldwide were analyzed. The median annual volume of IAT cases per institution was 40, and the median neurointerventional group size was three staff members. Independent predictors of case volume were presence of comprehensive stroke services and telestroke capability. The median minimum National Institutes of Health Stroke Scale score for treatment consideration was 8, although 60% of respondents reported no minimum score cut-off. There was no strict time window from symptom onset to treatment among 41% of respondents for anterior circulation strokes and among 56% for posterior circulation strokes, instead basing treatment decisions on clinical and imaging findings. Despite the emphasis on imaging-based selection, there was pronounced variability in the criteria used. Only 27% used one imaging approach exclusively. IAT following full- or partial-dose intravenous tissue plasminogen activator was performed by 89%. Mechanical devices were the predominant first-line therapy, but specific device usage depended on practice location. Approximately half preferred conscious sedation during IAT.

Conclusions

This survey illustrates significant variation among neurointerventionalists in the real-world use of IAT. Our findings highlight the need for evidence-based practice guidelines.
Regulation of transforming growth factor beta 1 gene expression by dihydropteridine reductase in kidney 293T cells
Authors: Gu Yanting , Gong Yuewen , Zhang Haojun , Dong Xi , Zhao Tingting , Burczynski Frank J. , Wang Guqi , Sun Sifan , Zhu Bin , Han Wenbing , Wang Hongpan , Li Ping
Published: December 2012

Quinoid dihydropteridine reductase (QDPR) is an enzyme involved in the metabolic pathway of tetrahydrobiopterin (BH4). BH4 is an essential cofactor of nitric oxide synthase (NOS) and can catalyze arginine to citrulline to release nitric oxide. Point mutations of QDPR have been found in the renal cortex of spontaneous Otsuka Long Evans Tokushima Fatty (OLETF) diabetic rats. However, the role of QDPR in DN is not clear. This study investigates the effects of QDPR overexpression and knockdown on gene expression in the kidney. Rat QDPR cDNA was cloned into pcDNA3.1 vector and transfected in human kidney cells (293T). The expression of NOS, transforming growth factor beta 1 (TGF-β1), Smad3, and NADPH oxidase were examined by RT–PCR and Western blot analyses. BH4 was assayed by using ELISA. Expression of QDPR was significantly decreased and TGF-β1 and Smad3 were increased in the renal cortex of diabetic rats. Transfection of QDPR into 293T cells increased the abundance of QDPR in cytoplasm and significantly reduced the expression of TGF-β1, Smad3, and the NADPH oxidases NOX1 and NOX4. Moreover, abundance of neuronal NOS (nNOS) mRNA and BH4 content were significantly increased. Furthermore, inhibition of QDPR resulted in a significant increase in TGF-β1 expression. In conclusion, QDPR might be an important factor mediating diabetic nephropathy through its regulation of TGF-β1/Smad3 signaling and NADPH oxidase.
Time–dose–mortality data and modeling for the entomopathogenic fungus Aschersonia placenta against the whitefly Bemisia tabaci
Authors: Qiu Junzhi , Song Feifei , Mao Lihui , Tu Jie , Guan Xiong
Published: December 2012

The fungus Aschersonia placenta FJSM was evaluated for control of the sweet potato whitefly, Bemisia tabaci. Bemisia tabaci nymphs (1st–4th instars) on tomato plants in the greenhouse (25–27 °C, 70%–85% relative humidity) were sprayed with suspensions containing 0, 104, 105, 106, 107, or 108 A. placenta FJSM conidia/mL. Mortality of fungus-treated 1st to 3rd instar nymphs ranged from 93% to 100% but was <25% for 4th instar nymphs; the fungus sporulated from 70% to 80% of the fungus-treated B. tabaci cadavers. LD50 and LD90 values decreased with time after treatment and increased with instar. LT50 values decreased with conidial concentration. The data were then described with time–dose–mortality models. The results indicate that A. placenta FJSM has potential as a mycoinsecticide for control of B. tabaci.
PROPAGATOR POLES AND AN EMERGENT STABLE STATE BELOW THRESHOLD: GENERAL DISCUSSION AND THE E(38) STATE
Authors: GIACOSA FRANCESCO , WOLKANOWSKI THOMAS
Published: December 2012

In the framework of a simple quantum field theory describing the decay of a scalar state into two (pseudo)scalar ones we study the pole(s) motion(s) of its propagator: besides the expected pole on the second Riemann sheet, we find — for a large enough coupling constant — a second, additional pole on the first Riemann sheet below threshold, which corresponds to a stable state. We then perform a numerical study for a hadronic system in which a scalar particle couples to pions. We investigate under which conditions a stable state below the two-pion threshold can emerge. In particular, we study the case in which this stable state has a mass of 38 MeV, which corresponds to the recently claimed novel scalar state E(38). Moreover, we also show that the resonance f0(500) and the stable state E(38) could be two different manifestations of the same "object". Finally, we also estimate the order of magnitude of its coupling to photons.
PHENOMENOLOGY OF RETAINED REFRACTORINESS: ON SEMI-MEMRISTIVE DISCRETE MEDIA
Authors: ADAMATZKY ANDREW , CHUA LEON O.
Published: December 2012

We study two-dimensional cellular automata, each cell takes three states: resting, excited and refractory. A resting cell excites if the number of excited neighbors lies in a certain interval (excitation interval). An excited cell becomes refractory independently on states of its neighbors. A refractory cell returns to a resting state only if the number of excited neighbors belong to recovery interval. The model is an excitable cellular automaton abstraction of a spatially extended semi-memristive medium where a cell's resting state symbolizes low-resistance and refractory state high-resistance. The medium is semi-memristive because only transition from high- to low-resistance is controlled by the density of local excitation. We present a phenomenological classification of the automata behavior for all possible excitation intervals and recovery intervals. We describe eleven classes of cellular automata with retained refractoriness based on the criteria of space-filling ratio, morphological and generative diversity, and types of traveling localizations.
COMPLEX BEHAVIOR IN COUPLED CHAOTIC CIRCUITS RELATED BY INTERMITTENCY AND ITS MODELING METHODS
Authors: UWATE YOKO , NISHIO YOSHIFUMI
Published: December 2012

We discover a complex behavior when switching three different synchronization states in two coupled chaotic circuits related to intermittency. Two methods to model this interesting complex behavior are proposed. First, we model this complex behavior by a first-order Markov chain with four states. Second, the modeling method by using 1-D Poincaré map derived from one chaotic circuit is proposed. We confirm that both modeling methods agree very well with computer simulations. Finally, we discuss the characteristics of two modeling methods for calculation times, modeling accuracy and application of large-scale systems.
DETECTING STRETCH-AND-FOLD MECHANISM IN CHAOTIC DYNAMICS
Authors: SHIMADA YUTAKA , YAMADA TAIJI , IKEGUCHI TOHRU
Published: December 2012

We propose a simple but effective visualization method for detecting the stretch-and-fold mechanism in chaotic dynamical systems. In the proposed method, we first place a hypersphere that is centered at a point on the trajectory of an attractor produced from the chaotic dynamical system. Second, we uniformly arrange points on the surface of the hypersphere. Third, we evolve the dynamics and observe the temporal evolution of the center point and the points on the surface. We then calculate the temporal evolution of the distances between the center point and the points on the surface. Finally, we express them using multiple colors and draw the colors representing the distances at the initial position on the hypersphere. Then, we observe the temporal changes of these colors generated by the temporal evolution of the distances. Application of the proposed method to chaotic dynamics results in the appearance of stripe patterns on the surface of the hypersphere over time. The results indicate that we can detect the stretch-and-fold mechanism, or the horse-shoe structure embedded in chaotic dynamics. We also discussed the reason for the generation of the stripe pattern under the framework of the proposed method.
POLYNOMIAL FIRST INTEGRALS FOR THE CHEN AND LÜ SYSTEMS
Authors: LLIBRE JAUME , VALLS CLAUDIA
Published: December 2012

We characterize all the values of the parameters for which the Chen and Lü systems have polynomial first integrals by using weight homogeneous polynomials and the method of characteristics for solving partial differential equations. We improve previous results which were not complete.
PARAMETRIC ANALYSIS OF BIFURCATION AND CHAOS IN A PERIODICALLY DRIVEN HORIZONTAL IMPACT PAIR
Authors: GUO YU , LUO ALBERT C. J.
Published: December 2012

In this paper, complex motions and chaos in the periodically driven horizontal impact pair are investigated using the theory of switchability for discontinuous dynamical systems. Domains and boundaries are defined due to the discontinuity caused by impacts. Analytical conditions for switching of stick and grazing motions are derived in detail. Generic mappings are introduced to describe different periodic motions and to identify the mapping structures of chaos. The periodic motions in such impact pair are analytically predicted, and the corresponding stability and bifurcation analysis of periodic motions are carried out. Parameter maps with different types of motions are developed. Periodic and chaotic motions with different mapping structures are illustrated numerically for a better understanding of physics of ball motions in the impact pair.
DESIGN AND CIRCUIT IMPLEMENTATION OF FRACTIONAL-ORDER MULTIWING CHAOTIC ATTRACTORS
Authors: TANG ZILONG , ZHANG CHAOXIA , YU SIMIN
Published: December 2012

In this paper, a novel approach is proposed for generating fractional-order multiwing chaotic attractors. Based on a fractional-order linear differential system, by introducing the nonlinear state feedback controller equipped with an even symmetric multisegment quadratic function, various fractional-order multiwing chaotic attractors can be generated. An improved module-based circuit is also designed for verifying the effectiveness of the proposed method.
TRANSITION CURVES AND BIFURCATIONS OF A CLASS OF FRACTIONAL MATHIEU-TYPE EQUATIONS
Authors: LEUNG A. Y. T. , GUO ZHONGJIN , YANG H. X.
Published: December 2012

A general version of the fractional Mathieu equation and the corresponding fractional Mathieu–Duffing equation are established for the first time and investigated via the harmonic balance method. The approximate expressions for the transition curves separating the regions of stability are derived. It is shown that a change in the fractional derivative order remarkably affects the shape and location of the transition curves in the n = 1 tongue. However, the shape of the transition curve does not change very much for different fractional orders for the n = 0 tongue. The steady state approximate responses of the corresponding fractional Mathieu–Duffing equation are obtained by means of harmonic balance, polynomial homotopy continuation and technique of linearization. The curves with respect to fractional order versus response amplitude, driving amplitude versus response amplitude with different fractional orders are shown. It can be found that the bifurcation point and stability of branch solutions is different under different fractional orders of system. When the fractional order increases to some value, the symmetric breaking, saddle-node bifurcation as well as period-doubling bifurcation phenomena are found and exhibited analytically by taking the driving amplitude as the bifurcation parameter.
BIFURCATION ANALYSIS OF SYNCHRONIZED REGIONS IN COMPLEX DYNAMICAL NETWORKS
Authors: TANG LONGKUN , LU JUN-AN , LÜ JINHU , YU XINGHUO
Published: December 2012

This paper aims to investigate the bifurcation phenomena of synchronized regions in complex dynamical networks with varying node parameters and fixed inner-linking matrices. In particular, by using the unified chaotic system as network nodes, this paper further explores the bifurcation patterns of synchronized regions with synchronous states of both equilibrium points and attractors in complex dynamical networks based on two types of inner-linking matrices, respectively. Our results indicate that there does not exist any bifurcation phenomenon in the above synchronized regions for some specific inner-linking matrices. It means that the stability of network synchronous state will not change for some specific inner-linking matrices as the parameter of node dynamics changes. However, the above synchronized regions generate various bifurcation patterns for some inner-linking matrices and varying node parameters as follows: (i) The unbounded–empty set bifurcation mode; (ii) The bounded–empty set bifurcation mode; (iii) The single bounded–multiple bounded–single bounded–empty set bifurcation mode; (iv) The unbounded–multiple disconnected–empty set bifurcation mode. All these results tell us that the inner-linking matrices play a key role for determining the bifurcation patterns of synchronized regions.
CHAOS IN NONAUTONOMOUS DISCRETE DYNAMICAL SYSTEMS APPROACHED BY THEIR INDUCED SYSTEMS
Authors: SHI YUMING
Published: December 2012

A nonautonomous discrete dynamical system is generated by a given sequence of maps. Its induced system is introduced. It is generated by a sequence of maps that are partial compositions of the given sequence of maps in the original order so that every orbit of the induced system is a part of an orbit of the original system starting from the same initial point. Some close relationships between chaotic dynamical behaviors of the original system and its induced systems are given, including chaos in the (strong) sense of Li–Yorke and Wiggins. Under some conditions, chaos in the (strong) sense of Li–Yorke of the original system and its induced systems is equivalent. By applying these relationships, several criteria of chaos are established and some sufficient conditions for no chaos are given for nonautonomous systems.
A ROBUST TIME-INTEGRATION ALGORITHM FOR SOLVING NONLINEAR DYNAMIC PROBLEMS WITH LARGE ROTATIONS AND DISPLACEMENTS
Authors: KUO SHYH-RONG , YAU J. D. , YANG Y. B.
Published: December 2012

An efficient time-integration algorithm for nonlinear dynamic analysis of structures is presented. By adopting the temporal discretization for time finite element approximation, very large time steps can be used by the algorithm. With an accuracy of fourth order, this technique requires only displacements and velocities to be made available at the start of the current time step for integration in state space. Using the weighted momentum principle, the problem of discontinuity caused by impulsive loads is resolved after time-integration of the applied load in external momentum. Since no knowledge is required of acceleration at the current time step, the errors caused by estimation of acceleration by previous finite-difference methods are circumvented. Moreover, an iterative procedure is included for each time step, involving the three phases of predictor, corrector, and error-checking. The effectiveness and robustness of the proposed algorithm in solving nonlinear dynamic problems is demonstrated in the numerical examples.
ESTIMATION OF RESPONSE OF PLATE STRUCTURE SUBJECT TO LOW VELOCTIY IMPACT BY A SOLID OBJECT
Authors: YANG Y. , LAM N. T. K. , ZHANG L.
Published: December 2012

This paper introduces the use of a two-degree-of-freedom (2DOF) model which comprises two spring-connected lumped masses for analyzing the response behavior of a plate structure to a low velocity impact of a flying solid object. We propose a novel method for calculating the value of the equivalent lumped mass and that of the spring constant which characterizes the 2DOF model. This is an important contribution given that existing calculation methods that are based on results from modal analysis would only be suitable for modeling the impact actions of wind or blast. Analysis involving the use of a 2DOF model is inexpensive and convenient to operate whilst achieving very good accuracies as demonstrated herein. By contrast, modeling impact response behavior by finite element analyses can be very time consuming and labour intensive because of the need to model in detail the impactor in contact with the target.
FREE VIBRATION OF TAPERED TIMOSHENKO BEAMS BY DEFORMATION DECOMPOSITION
Authors: LEE BYOUNG KOO , OH SANG JIN , LEE TAE EUN
Published: December 2012

This paper deals with the free vibration of tapered Timoshenko beams. The simultaneous differential equations governing the free vibration of tapered Timoshenko beams are derived by decomposing the deformations of the beam into components as transverse deflection, bending rotation and shear distortion. The governing differential equations are first integrated by the Runge–Kutta method and then solved by the determinant search method, combined with the Regula–Falsi method, to obtain the natural frequencies of the beam along with their corresponding mode shapes. In the numerical examples, the effects of various parameters on the frequencies and mode shapes of the beam are extensively discussed.
EXPERIMENTAL STUDY OF LOAD CAPACITIES OF TUBULAR STEEL ADJUSTABLE SHORES USED IN CONSTRUCTION
Authors: PENG JUI-LIN , WU CHUNG-WEI , SHIH MING-HSIANG , YANG YEONG-BIN
Published: December 2012

In this study, experimental tests were performed to investigate the load capacities of tubular steel adjustable shores in setups typically employed in construction sites, both for isolated units and combined systems. As for isolated units, the column curves of isolated tubular steel adjustable shores for a wide range were presented based on the test results. These curves can be used for interpolating the strength of tubular steel adjustable shores in design, instead of relying on extrapolation that may lead to uncertainties. The test results show that the overlap length between the connecting tube and base tube of the shore does not affect substantially the load capacity. Additionally, the load capacity of a 3-section tubular steel adjustable shore is lower than that of a 2-section shore. The load capacity of tubular steel adjustable shores decreases when No. 3 steel bars, instead of tube locks, are used. As for the combined systems, the reinforcing effect for a tubular steel adjustable shoring system with less than 16 shores is negligible when reinforced horizontally. For a tubular steel adjustable shoring system with four shores, the reinforcing effect is obvious when reinforced both horizontally and diagonally. This study also introduces the novel concept of upper and lower limit values of load capacity, which embrace the maximum and minimum strengths of all tested shoring members randomly selected for testing at the construction site. This concept can be potentially applied in shoring design.
CATALYTIC SYNTHESIS AND GROWTH MECHANISM OF TUNGSTEN NANOWIRE ARRAYS ON SIO2 SUBSTRATES
Authors: WANG C. , HE Y. H. , HOU L. Z. , WANG S. L. , LIU X. L. , ZHANG Q. , PENG C. Q.
Published: December 2012

Single-crystalline W nanowires, with approximately 150 nm in diameter and 15 μm in length, have been successfully synthesized on SiO2 substrates by chemical vapor deposition (CVD) with the assistance of Ni catalysts at 950°C. The catalysts located at the tip of W nanowires were found to be Ni4W in a solid state, rather than a liquid state. The low-temperature growth of W nanowires using the solid catalysts can be generally accessible, provided that the appropriate combination of solid catalysts and nanowires are thermodynamically available, thus suggesting the implication for the potentially large-area integrated growth on various substrates. The growth direction of the generated [100]-oriented W nanowires was presumed to be determined by the orientation relationship between the solid Ni catalyst particle and the W precipitate. A possible catalytic growth model was proposed according to the analysis of the experimental results. The orientation relationship between the solid catalyst particle and the corresponding nanowire was expected to be also valid for some other nanowires induced by solid catalyst.
Roles of default-mode network and supplementary motor area in human vigilance performance: evidence from real-time fMRI
Authors: Hinds Oliver , Thompson Todd W. , Ghosh Satrajit , Yoo Julie J. , Whitfield-Gabrieli Susan , Triantafyllou Christina , Gabrieli John D. E.
Published: December 2012

We used real-time functional magnetic resonance imaging (fMRI) to determine which regions of the human brain have a role in vigilance as measured by reaction time (RT) to variably timed stimuli. We first identified brain regions where activation before stimulus presentation predicted RT. Slower RT was preceded by greater activation in the default-mode network, including lateral parietal, precuneus, and medial prefrontal cortices; faster RT was preceded by greater activation in the supplementary motor area (SMA). We examined the roles of these brain regions in vigilance by triggering trials based on brain states defined by blood oxygenation level-dependent activation measured using real-time fMRI. When activation of relevant neural systems indicated either a good brain state (increased activation of SMA) or a bad brain state (increased activation of lateral parietal cortex and precuneus) for performance, a target was presented and RT was measured. RTs on trials triggered by a good brain state were significantly faster than RTs on trials triggered by a bad brain state. Thus human performance was controlled by monitoring brain states that indicated high or low vigilance. These findings identify neural systems that have a role in vigilance and provide direct evidence that the default-mode network has a role in human performance. The ability to control and enhance human behavior based on brain state may have broad implications.
Identification of two forebrain structures that mediate execution of memorized sequences in the pigeon
Authors: Helduser Sascha , Cheng Sen , Güntürkün Onur
Published: December 2012

The execution of action sequences is the basis of most behavior. However, little is known about the neural foundation of visuomotor sequence execution in birds, although pigeons are a classic model animal to study sequence learning and production. Recently, we identified two structures in the pigeon brain, the nidopallium intermedium medialis pars laterale (NIML) and the nidopallium caudolaterale (NCL), that are involved in the execution of a serial reaction time task (SRTT). In the SRTT sequence execution is always cue guided. Thus the previous study could not unambiguously clarify whether NCL and NIML contribute to a memory-based execution of sequential behavior. In addition, a possibly differential role of these two structures could not be identified. Therefore, the present study was conducted to further elucidate the role of NCL and NIML in sequence execution in a task where pigeons performed a memorized four-item sequence. Transient inactivation of each NIML and NCL severely impaired sequence execution. The results confirm and extend our previous findings. NIML and NCL seem to store sequence information in parallel. However, the results support the hypothesis that NCL, in contrast to NIML, is especially required for sequence initiation.
A Novel Mesh Quality Improvement Method for Boundary Elements
Authors: Liu Hou-lin , Dai Cui , Dong Liang , Tan Ming-gao
Published: December 2012

In order to improve the boundary mesh quality while maintaining the essential characteristics of discrete surfaces, a new approach combining optimization‐based smoothing and topology optimization is developed. The smoothing objective function is modified, in which two functions denoting boundary and interior quality, respectively, and a weight coefficient controlling boundary quality are taken into account. In addition, the existing smoothing algorithm can improve the mesh quality only by repositioning vertices of the interior mesh. Without destroying boundary conformity, bad elements with all their vertices on the boundary cannot be eliminated. Then, topology optimization is employed, and those elements are converted into other types of elements whose quality can be improved by smoothing. The practical application shows that the worst elements can be eliminated and, with the increase of weight coefficient, the average quality of boundary mesh can also be improved. Results obtained with the combined approach are compared with some common approach. It is clearly shown that it performs better than the existing approach.
Electrokinetic Treatment for Model Caissons with Increasing Dimensions
Authors: Mohamedelhassan Eltayeb , Curtain Kevin , Fenos Matt , Girard Kevin , Provenzano Anthony , Tabaczuk Wesley
Published: December 2012

Electrokinetic treatment has been known in geotechnical engineering for over six decades, yet, the technique is rarely used. This stems from the absence of design guidelines and specifications for electrokinetic treatment systems. An important issue that need to be investigated and understood in order to devise guidelines from experimental results is the effect of the foundation element size on the outcome of the treatment. Also important is determining the optimum distance between the electrodes and estimating the energy consumption prior to treatment. This experimental study is a preliminary step in understanding some of the issues critical for the guidelines and specifications. Four model caissons with surface areas between 16000 and 128000 mm2were embedded in soft clayey soil under water and treated for 168 hr with a dc voltage of 6 V. From the results, a distance between the anode (model caisson) and the cathode equal 0.25 times the outside diameter of the model caisson was identified as optimum. Relationships between the surface area and axial capacity of the model caisson and the surface area and energy consumption were presented. The equations can be used to preliminary estimate the load capacity and the energy consumption for full-scale applications.
Ocean Cooling Pattern at the Last Glacial Maximum
Authors: Zhuang Kelin , Giardino John R.
Published: December 2012

Ocean temperature and ocean heat content change are analyzed based on four PMIP3 model results at the Last Glacial Maximum relative to the prehistorical run. Ocean cooling mostly occurs in the upper 1000 m depth and varies spatially in the tropical and temperate zones. The Atlantic Ocean experiences greater cooling than the rest of the ocean basins. Ocean cooling is closely related to the weakening of meridional overturning circulation and enhanced intrusion of Antarctic Bottom Water into the North Atlantic.
Hopf Bifurcation of a Predator‐Prey System with Delays and Stage Structure for the Prey
Authors: Zhang Zizhen , Yang Huizhong
Published: December 2012

This paper is concerned with a Holling type III predator‐prey system with stage structure for the
prey population and two time delays. The main result is given in terms of local stability and bifurcation. By choosing the time delay as a bifurcation parameter, sufficient conditions for the local stability of the positive equilibrium and the existence of periodic solutions via Hopf bifurcation with respect to both delays are obtained. In particular, explicit formulas that can determine the direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions are established by using the normal form method and center manifold theorem. Finally, numerical simulations supporting the theoretical analysis are also included.
Soliton Solutions for the Wick‐Type Stochastic KP Equation
Authors: Guo Y. F. , Ling L. M. , Li D. L.
Published: December 2012

The Wick‐type stochastic KP equation is researched. The stochastic single‐soliton solutions and stochastic multisoliton solutions are shown by using the Hermite
transform and Darboux transformation.
A Quasistatic Contact Problem for Viscoelastic Materials with Slip‐Dependent Friction and Time Delay
Authors: Yao Si-sheng , Huang Nan-jing
Published: December 2012

A mathematical model which describes an explicit time‐dependent quasistatic frictional contact problem between a deformable body and a foundation is introduced and studied, in which the contact is bilateral, the friction is modeled with Tresca’s friction law with the friction bound depending on the total slip, and the behavior of the material is described with a viscoelastic constitutive law with time delay. The variational formulation of the mathematical model is given as a quasistatic integro‐differential variational inequality system. Based on arguments of the time‐dependent variational inequality and Banach′s fixed point theorem, an existence and uniqueness of the solution for the quasistatic integro‐differential variational inequality system is proved under some suitable conditions. Furthermore, the behavior of the solution with respect to perturbations of time‐delay term is considered and a convergence
result is also given.
On the Self‐Intersection Local Time of Subfractional Brownian Motion
Authors: Liu Junfeng , Peng Zhihang , Tang Donglei , Cang Yuquan
Published: December 2012

We study the problem of self‐intersection local time of d‐dimensional subfractional Brownian motion based on the property of chaotic representation and the white noise analysis.