bluuebunny/crossref_metadata_2025 huggingface dataset:
Interchromatin granules in plant nuclei
Authors: Medina Maria Asuncion , De La Espina Susana Moreno Diaz , Martin Marta , Fernandez‐Gomez Maria Encarnacion
Published: February 2012

The interchromatin granules (IG) are well characterized subnuclear structures in animal cell nuclei which form a part of the internal nuclear matrix and are supposed to correspond to accummulation sites of snRNPs and/or maturation and transport of rRNPs; but similar structures have not yet been characterized in plant nuclei.

Using the bismuth impregnation technique of Locke and Huie, preferential for the staining of IG, we describe here a kind of positive granules 20–25 nm in diameter in plants. The putative plant IG have a series of common characteristics with animal IG, which are not found as a whole in any other subnuclear structures. These are: size, morphology and ultrastructural organization, presence in groups, EDTA and bismuth oxynitrate positive reactions, resistance to double digestion with proteases and RNase I and their high content in phosphorylated proteins. For all the above and also because they are ubiquitous structures in the plant nuclei, we identified these granules with the IG described in animal cells.
Interplay between bone marrow and liver in the pathogenesis of hepatic fibrosis
Authors: Inagaki Yutaka , Higashiyama Reiichi
Published: February 2012

Recent advances in the technologies of both molecular biology and regenerative medicine have made it possible to identify bone marrow (BM)‐derived cells migrating into various fibrotic organs including the liver. A number of studies have reported that BM‐derived cells migrating into fibrotic liver tissue exhibit a myofibroblast‐like phenotype and may participate in the progression of liver fibrosis. On the other hand, it has also been shown that BM‐derived cells express matrix metalloproteinases and contribute to the regression of experimental liver fibrosis. These contradictory results may arise, at least in part, from the uncertainty of various different methods that have been used in those studies. In this review article, we describe the interplay between BM and liver in the progression and regression of liver fibrosis, with an emphasis on the necessity of qualified methods with high specificity and sensitivity to evaluate the role of BM‐derived cells in collagen production.
A (Different) Virtue Epistemology
Authors: GRECO JOHN
Published: February 2012

Section 1 articulates a genus‐species claim: that knowledge is a kind of success from ability. Equivalently: In cases of knowledge, S’s success in believing the truth is attributable to S’s ability. That idea is then applied to questions about the nature and value of knowledge. Section 2 asks what it would take to turn the genus‐species claim into a proper theory of knowledge; that is, into informative, necessary and sufficient conditions. That question is raised in the context of an important line of objection against even the genus‐species claim; namely, that there is no way to understand the attribution relation so that it does all the work that it is supposed to do. Section 3 reviews several extant proposals for understanding the attribution relation, and argues that none of them are adequate for answering the objection. Section 4 proposes a different way of understanding the relation, and shows how the resulting view does resolve the objection. Section 5 completes the new account by proposing a way to understand intellectual abilities. Section 6 briefly addresses Barn Façade cases and lottery propositions. Section 7 briefly addresses a question about the scope of knowledge; in particular, it shows how the new view allows a neo‐Moorean response to skepticism.
A clinical knowledge measurement tool to assess the ability of community pharmacists to detect drug-related problems
Authors: Williams Mackenzi , Peterson Gregory M , Tenni Peter C , Bindoff Ivan K
Published: February 2012

Introduction

Drug-related problems (DRPs) are associated with significant morbidity and mortality, with most DRPs thought to be preventable. Community pharmacists can detect and either prevent or resolve many of these DRPs. A survey-based clinical knowledge measurement tool was designed and validated to estimate a community pharmacist's clinical knowledge and ability to detect and appropriately resolve DRPs.

Methods

Nine clinical cases with seven multiple-choice statements (63 statements in total) were constructed, based on scenarios that were found to occur frequently in Australian community pharmacies. The statements aimed to assess a pharmacist's ability to identify, gather relevant information about and make appropriate recommendations to resolve, a DRP. The survey was pilot tested with 18 academics at three Australian pharmacy schools, resulting in the removal of 23 statements. The survey was then administered to undergraduate pharmacy students (28 fourth-year, 41 third-year and 42 first-year students) and to 433 Australian community pharmacists who were participating in an intervention documentation trial. The pharmacists' resultant survey scores were correlated against their actual rate of documenting clinical interventions.

Results

The tool had relatively good internal consistency. Significant differences were seen between the three groups of students (P < 0.01). Community pharmacists with additional clinical qualifications had a significantly higher score than other participating pharmacists (P < 0.01). A moderate, but significant, correlation was seen between the pharmacists' survey score and their clinical intervention rate in practice during the trial (P < 0.01).

Conclusion

The clinical knowledge measurement tool appeared to estimate a pharmacist's ability to detect and resolve DRPs within the community pharmacy environment.
The voltage dependence of Ih in human myelinated axons
Authors: Howells James , Trevillion Louise , Bostock Hugh , Burke David
Published: February 2012

Key points 

Pacemaking in cardiac and neuronal cells is primarily controlled by the interaction between different voltage gated ion channels, and in particular the hyperpolarization‐activated cyclic‐nucleotide gated (HCN) family of channels.

HCN channels are activated by membrane hyperpolarization and play a key role in the determination of resting membrane potential.

We provide evidence suggesting that differences in (i) the modulation and expression of HCN channels, (ii) the expression of slow K+ channels; and (iii) the resultant changes in resting membrane potential are the major determinants of the functional differences between human motor and sensory axons.

Contrary to current wisdom, this study supports the view that the greater persistent Na+ current observed in sensory axons is not due to greater expression of persistent Na+ channels but instead to the relatively depolarized membrane potential driving greater resting activation.
Investigation of Positional Error in Two Degree of Freedom Mechanism With Joint Clearance
Authors: Jawale H. P. , Thorat H. T.
Published: February 2012

Closed chain mechanisms are used as robotic manipulators with special features. A planar two-DOF closed loop mechanism provides desired position of an end effecter in a confined workspace with two input motions. Position of end effecter depends on various factors including joint clearance. Positional accuracy forms important parameter for kinematic analysis of mechanism. This paper presents simple approach for quantifying error due to joint clearance in a two-DOF mechanism. Generalized scheme for positional deviation with and without clearance at joint is presented. Orientation of clearance links for maximum positional error is identified. Error at various positions is quantified in relation with clearance link length. Computer programming is used as a tool to workout positional analysis of mechanism. Results show that error is independent of magnitude of clearance, however, a function of location of end effecter in workspace.
An Experimental Investigation of Hydrogen Fumigation in a Small Direct-Injection Diesel Engine During Part-Load Operation
Authors: Marin William E. , Wiese Daniel P. , Erickson Paul A.
Published: February 2012

Hydrogen enrichment may offer enhanced performance of internal combustion engines. Hydrogen’s high specific energy, wide flammability limits, and high flame speed are all desirable traits that can potentially enhance combustion. However, hydrogen’s low energy density and its need to be produced from another energy source pose significant challenges for implementation. Hydrogen enrichment involves co-firing of hydrogen and another primary fuel. The hydrogen can be aspirated through the intake manifold via fumigation or injected at the port or cylinder with the primary fuel. The effect of hydrogen fumigation in diesel engines has been studied to some degree but is not fully understood. In this research, a single-cylinder four-stroke direct-injection diesel engine was modified for hydrogen fumigation and was instrumented to monitor combustion related performance parameters. This engine is representative of low-cost systems that are widely used in developing nations for agricultural and other low power applications. A factorial design of experiments was implemented to study the effects and interactions of hydrogen fumigation flow rate, injection timing, and diesel fuel flow rate on part-load engine performance. At relatively low energy fractions, hydrogen was found to have statistically insignificant effects on brake torque and indicated mean effective pressure, leading to modest decreases in brake thermal efficiency. Exhaust gas temperature increased with hydrogen enrichment. The coefficient of variance of indicated mean effective pressure decreased with hydrogen enrichment, and visible changes to the in-cylinder pressure trace were observed, particularly when injection timing was retarded. The results of this investigation show that for this specific configuration, hydrogen enrichment is not beneficial to the combustion process. The marginal improvements in coefficient of variance and changes of in-cylinder pressure cannot justify the decrease in thermal efficiency of the engine.
Nanosize Metal Oxide Particle Emissions From Diesel- and Petrol-Engines
Authors: Mayer A. , Czerwinski J. , Kasper M.
Published: February 2012

All internal combustion piston engines emit nanoparticles. Part of them are soot particles as a results of incomplete combustion of fuels, or lube oil. Another part are metal particles, most probably oxides, commonly called ash. A major source of metal particles is engine wear and corrosion. The lube oil reentraines these abraded particles into the combustion zone. There they are partially vaporized and ultrafine oxide particles formed through nucleation [1]. Other sources are metallic additives to the lube oil, or the fuel, and debris from the catalytic coatings in the exhaust-gas after-treatment. The formation process results in extremely fine particles, typically smaller than 50 nm. Thus they can intrude through the alveolar membranes directly into the human organism and can even penetrate the cell nucleus [5]. The consequent health risk necessitates a careful investigation of these emissions and effective curtailment. Substantial information is available on Diesel engine particulate emissions, [2, 3, 4] but there are almost no results for SI engines reported. Beside an example of metal oxide particles from a Diesel engine, [2], the present paper shows some preliminary results of particle mass and nanoparticle emissions of SI engines. Four SI engines were investigated: two older and two newer engines, comprising two car engines and two motorbikes. The tests were done on standard transient driving cycles, and steady-state at constant 50 km/h and idling because prior to this study high concentrations of ash were observed with Diesels during idling, [2]. All tests were done with particle samples collected from the CVS tunnel, during long operating periods, to have sufficient material for analyzing. At the steady-state points, the particle size spectra were measured and based on this the source as “ash” postulated. The results show that the older engines emit high concentrations of both soot and ash particles. The size distribution is bimodal for soot and ash particles. The newer engines’ emission results are less uniform and the concentrations are lower, as expected. Altogether, the concentrations of these ash particles in the exhaust gas of Diesel and SI-engines can be so high, that more detailed investigations are requiredy.
An Analysis of the Production of Hydrogen and Hydrocarbon Species by Diesel Post Injection Combustion
Authors: Jeftic´ Marko , Asad Usman , Han Xiaoye , Xie Kelvin , Yu Shui , Wang Meiping , Zheng Ming
Published: February 2012

The effects of post injection on the combustion efficiency, exhaust emissions, and in-cylinder hydrogen generation were experimentally investigated in a modern heavy duty diesel engine. As the post injection was moved away from top dead center (TDC), the test results generally showed increasing carbon monoxide (CO) and total hydrocarbons (THC), fairly constant nitrogen oxide (NOx) emissions while the smoke emissions were more sensitive to the post injection timing. Hydrogen production was observed to be higher at later post injection timings. In a majority of instances, hydrogen production and carbon monoxide formation were very well correlated. Additional tests explored the effects of the overall air-to-fuel ratio on the in-cylinder hydrogen production and the experimental results indicated that a lower air-to-fuel ratio seemed to promote the in-cylinder generation of hydrogen. However, the increased hydrogen production was offset by less efficient power production from the post injection combustion. A Fourier transform infrared (FTIR) spectroscopy analysis of hydrocarbon emissions was carried out in an attempt to determine the effects of diesel post injection timing on individual light hydrocarbon species.
Real-Time Transient Soot and NOX Virtual Sensors for Diesel Engine Using Neuro-Fuzzy Model Tree and Orthogonal Least Squares
Authors: Johri Rajit , Salvi Ashwin , Filipi Zoran
Published: February 2012

Diesel engine combustion and emission formation is highly nonlinear and thus creates a challenge related to engine diagnostics and engine control with emission feedback. This paper presents a novel methodology to address the challenge and develop virtual sensing models for engine exhaust emission. These models are capable of predicting transient emissions accurately and are computationally efficient for control and optimization studies. The emission models developed in this paper belong to the family of hierarchical models, namely “neuro-fuzzy model tree”. The approach is based on divide-and-conquer strategy i.e. to divide a complex problem into multiple simpler subproblems, which can then be identified using simpler class of models. Advanced experimental setup incorporating a medium duty diesel engine is used to generate training data. Fast emission analyzers for soot and NOX provide instantaneous engine-out emissions. Finally, the Engine-In-the-Loop is used to validate the models for predicting transient particulate mass and NOX.
Exploiting the Anti-HIV-1 Activity of Acyclovir: Suppression of Primary and Drug-Resistant HIV Isolates and Potentiation of the Activity by Ribavirin
Authors: Vanpouille Christophe , Lisco Andrea , Introini Andrea , Grivel Jean-Charles , Munawwar Arshi , Merbah Melanie , Schinazi Raymond F. , Derudas Marco , McGuigan Christopher , Balzarini Jan , Margolis Leonid
Published: February 2012

Multiple clinical trials have demonstrated that herpes simplex virus 2 (HSV-2) suppressive therapy using acyclovir (ACV) or valacyclovir in HIV-1/HSV-2-infected persons increased the patient's survival and decreased the HIV-1 load. It has been shown that the incorporation of ACV-monophosphate into the nascent DNA chain instead of dGMP results in the termination of viral DNA elongation and directly inhibits laboratory strains of HIV-1. We evaluated here the anti-HIV activity of ACV against primary HIV-1 isolates of different clades and coreceptor specificity and against viral isolates resistant to currently used drugs, including zidovudine, lamivudine, nevirapine, a combination of nucleoside reverse transcriptase inhibitors (NRTIs), a fusion inhibitor, and two protease inhibitors. We found that, at clinically relevant concentrations, ACV inhibits the replication of these isolates in human tissues infected
ex vivo
. Moreover, addition of ribavirin, an antiviral capable of depleting the pool of intracellular dGTP, potentiated the ACV-mediated HIV-1 suppression. These data warrant further clinical investigations of the benefits of using inexpensive and safe ACV alone or in combination with other drugs against HIV-1, especially to complement or delay highly active antiretroviral therapy (HAART) initiation in low-resource settings.
Efflux Pumps of Mycobacterium tuberculosis Play a Significant Role in Antituberculosis Activity of Potential Drug Candidates
Authors: Balganesh Meenakshi , Dinesh Neela , Sharma Sreevalli , Kuruppath Sanjana , Nair Anju V. , Sharma Umender
Published: February 2012

Active efflux of drugs mediated by efflux pumps that confer drug resistance is one of the mechanisms developed by bacteria to counter the adverse effects of antibiotics and chemicals. To understand these efflux mechanisms in
Mycobacterium tuberculosis
, we generated knockout (KO) mutants of four efflux pumps of the pathogen belonging to different classes. We measured the MICs and kill values of two different compound classes on the wild type (WT) and the efflux pump (EP) KO mutants in the presence and absence of the efflux inhibitors verapamil and
l
-phenylalanyl-
l
-arginyl-β-naphthylamide (PAβN). Among the pumps studied, the efflux pumps belonging to the ABC (ATP-binding cassette) class, encoded by
Rv1218c
, and the SMR (small multidrug resistance) class, encoded by
Rv3065
, appear to play important roles in mediating the efflux of different chemical classes and antibiotics. Efflux pumps encoded by
Rv0849
and
Rv1258c
also mediate the efflux of these compounds, but to a lesser extent. Increased killing is observed in WT
M. tuberculosis
cells by these compounds in the presence of either verapamil or PAβN. The efflux pump KO mutants were more susceptible to these compounds in the presence of efflux inhibitors. We have shown that these four efflux pumps of
M. tuberculosis
play a vital role in mediating efflux of different chemical scaffolds. Inhibitors of one or several of these efflux pumps could have a significant impact in the treatment of tuberculosis. The identification and characterization of
Rv0849
, a new efflux pump belonging to the MFS (major facilitator superfamily) class, are reported.
Factors shaping gene flow in red deer (Cervus elaphus) in seminatural landscapes of central Europe
Authors: Niedziałkowska M. , Fontaine M.C. , Jędrzejewska B.
Published: February 2012

We studied gene flow and connectivity between three subpopulations and nine groups of red deer ( Cervus elaphus L., 1758) occurring in forests in northeastern Poland and western Belarus. The red deer in this region mostly originated from translocated individuals that were introduced primarily in the 19th and 20th centuries. The genetic structure of the population has been identified during the previous study. Using 14 microsatellite loci, we detected 14 first-generation migrants between the three subpopulations and 21 among the nine groups of deer. The number of effective migrants (Nm) was estimated to be 2.5 individuals/generation between the subpopulations and 6.2 individuals/generation between the groups. About 80% of first-generation migrants moved less than 150 km. The gene flow of hinds and stags was similar. A least cost path (LCP) analysis was performed using different habitat types: deciduous and mixed forests, coniferous forests, wetlands, meadows, arable lands, scarce settlements, dense settlements, and waters. No significant barriers to dispersal were detected, but individual dispersal was restricted in space by the significant isolation by distance. The best model, explaining the genetic distance (FST/1 – FST) between the forests, suggested that LCP corridor length limited gene flow and high forest cover within LCP corridors increased gene flow among the forests.
Genetically modified growth affects allometry of eye and brain in salmonids
Authors: Devlin R.H. , Vandersteen W.E. , Uh M. , Stevens E.D.
Published: February 2012

Effects of growth acceleration on eye development have been examined in genetically modified salmonids. Growth hormone (GH) transgenic coho salmon ( Oncorhynchus kisutch (Walbaum, 1792)) show dramatically elevated overall body growth and an absolute increase in eye size, but relative eye growth is shifted from negatively allometric to more isometric. Thus, transgenic fish possess significantly smaller eyes relative to nontransgenic fish of the same size. Ration-restricted limitation of growth in transgenic salmon to that of wild type restores relative eye growth rate, suggesting that effects on eyes are an indirect consequence of modification of growth rate rather than a direct effect of GH overexpression. Heart, spleen, and liver did not show changes in proportion among groups, whereas total brain size showed the same response as eye. Relative eye and brain size were also reduced in a fast-growing domesticated strain of rainbow trout ( Oncorhynchus mykiss (Walbaum, 1792)), suggesting modifications of allometry are a more general effect of growth acceleration. GH mRNA levels from the transgene were elevated in eyes, whereas IGF-I mRNA was not, suggesting this organ may be regulated in a different fashion than other organs. Neural tissues with critical structural requirements for optimal function may be subject to less modification of growth rate than are other organ systems.
Effects of supplementation with preferred foods on the reproductive axis of American Goldfinches (Spinus tristis)
Authors: Furlonger A.A. , Huynh L. , Luloff T.W. , Schmidt K.L. , MacDougall-Shackleton S.A.
Published: February 2012

Numerous field studies indicate that food supplementation of birds can advance laying date. In addition, laboratory studies, though less common, suggest that altering the amount of food, the predictability of food, or food type can affect reproductive physiology. American Goldfinches ( Spinus tristis , formerly Carduelis tristis (L., 1758)) breed in late summer when thistle (Cynareae) seeds become abundant, suggesting that specific food types may affect their reproductive physiology. We tested whether supplementation with preferred seeds would affect reproductive physiology of male and female American Goldfinches. Birds were photostimulated and fed a standard pellet diet, or supplemented with a variety of preferred seeds. Supplemented females developed larger ovarian follicles. Supplemented males had higher levels of plasma testosterone, but only if they were also housed with a female. These results suggest that preferred seed types can act as a supplementary cue in this species, and fine-tune photoperiod-driven changes in reproductive physiology.
Ionic regulation and shell mineralization in the bivalveAnodonta cygnea(swan mussel) following heavy-metal exposure
Authors: Lopes-Lima Manuel , Freitas Susana , Pereira Liliana , Gouveia Eugenia , Hinzmann Mariana , Checa Antonio , Machado Jorge
Published: February 2012

Freshwater mussels are one of the most imperiled faunistic groups in the world and environmental exposure to toxic heavy metals, which result in deregulation of calcium absorption and deposition in the laboratory, may be a contributing factor in their decline. To address potential effects of heavy-metal exposure on calcium transport and metabolism in freshwater bivalves, adult Anodonta cygnea (L., 1758) were exposed to a sublethal concentration (1.0 × 10−6 mol/L) of essential (Zn2+and Cu2+) or nonessential (Pb2+and Cr3+) metal for 30 days in the laboratory. Inorganic composition of extrapallial, haemolymph, heart, and pericardium fluids, and kidney tissue, as well as shell morphology by scanning electron microscopy, were compared in treated and untreated mussels. Calcium levels in fluids varied after exposure to any of the metals investigated, although the magnitude and threshold of effect were metal- and compartment-specific. Ca2+levels increased robustly in all fluids following exposure to Zn2+, Cu2+, or Cr3+, whereas levels decreased significantly in heart fluid alone following Pb2+exposure (p < 0.05). In constrast to exposure to the other metals, Cu2+revealed an interesting reverse-accumulation pattern, decreasing in the fluids but not in the kidney, where it clearly accumulates for excretion. In addition, whereas essential Cu2+and Zn2+are closely regulated, the nonessential metals Pb2+and Cr3+increase to very high levels. Drastic alterations in shell morphology, specifically the structure of border and inner pallial regions of the nacreous layer, were observed after Cu2+or Cr3+exposure. Collectively, data suggest that prolonged exposure to a sublethal concentration of these heavy metals can adversely affect compartmental calcium availability and shell composition in A. cygnea.
Beach and demersal spawning in capelin (Mallotus villosus) on the northeast Newfoundland coast: egg developmental rates and mortality
Authors: Penton P.M. , Davoren G.K. , Montevecchi W.A. , Andrews D.W.
Published: February 2012

Timing of spawning and site selection in fish are important fitness-related traits that ultimately influence reproductive success. Capelin ( Mallotus villosus (Müller, 1776)), a key forage fish in the north Atlantic, spawn eggs that adhere to sediments on beaches and in demersal (deep-water) habitats throughout their geographic range, resulting in divergent thermal regimes for the incubating eggs. We compare the timing and duration of spawning of capelin and its influence on the developmental and survival rates of eggs between a beach and a demersal spawning site on the northeast Newfoundland coast in 2004 and 2005. Spawning events at the beach were at least 10 days earlier and shorter (2–3 days) relative to the demersal site (8–12 days). Hourly and mean daily incubation temperatures at the beach were higher and more variable relative to the demersal site, resulting in two distinct developmental strategies: low to high mortality and rapid development (beach) versus low mortality and slow development (demersal). Higher egg mortality at beach sites was explained by higher and more variable temperatures and potentially limited oxygen replenishment relative to demersal sites. The divergent biology of beach and demersally spawned eggs suggest that each will respond differently to environmental change and, thus, require different approaches for successful management.
DIFFUSION DEPENDING ON LINEAR MOMENTUM FOR CONTINUUM STATES
Authors: SCHEID WERNER , ISAR AURELIAN , SANDULESCU AUREL
Published: February 2012

Based on the Lindblad theory we study a quantum mechanical diffusion which depends only on the operator of the linear momentum and acts on the density matrix of wave packets. The density is assumed initially as coherent and gets incoherently with time.
GRAPHICAL QUANTUM ERROR-CORRECTING CODES BASED ON ENTANGLEMENT OF SUBGRAPHS
Authors: LI YUAN , XU MANTAO , SUN QIANG
Published: February 2012

Graphical approach provides a more intuitive and simple way to construct error correction codes. How to obtain generator matrix is the key problem of constructing graphical quantum codes. In this paper, we further generalize the graphical quantum code construction method by entangling its disconnected subgraphs, so that the corresponding generator matrix of quantum nondegenerate codes can be easily obtained. By making use of the method of subgraphs entangling, we also point out its application in adjacency matrix constructions of larger colorable graph and graphical quantum nested codes.
CHAOS AND WEATHER FORECASTING: THE ROLE OF THE UNSTABLE SUBSPACE IN PREDICTABILITY AND STATE ESTIMATION PROBLEMS
Authors: TREVISAN ANNA , PALATELLA LUIGI
Published: February 2012

In the first part of this paper, we review some important results on atmospheric predictability, from the pioneering work of Lorenz to recent results with operational forecasting models. Particular relevance is given to the connection between atmospheric predictability and the theory of Lyapunov exponents and vectors. In the second part, we briefly review the foundations of data assimilation methods and then we discuss recent results regarding the application of the tools typical of chaotic systems theory described in the first part to well established data assimilation algorithms, the Extended Kalman Filter (EKF) and Four Dimensional Variational Assimilation (4DVar). In particular, the Assimilation in the Unstable Space (AUS), specifically developed for application to chaotic systems, is described in detail.
EXTREME VALUE STATISTICS FOR DETERMINISTIC DYNAMICAL SYSTEMS
Authors: BALAKRISHNAN V.
Published: February 2012

The cumulative distribution function (CDF) of the maximum in a time series generated by different kinds of deterministic dynamics is computed, in the framework of prototypical models of such dynamics. This CDF is shown to be significantly different in form from that of the maximum in a sequence of identically distributed random variables. In the latter case, the CDF is generically in the domain of attraction of one of the three extreme value distributions. This property is not shared by the CDF for deterministic dynamics. The characteristic features of the CDF are elucidated in the case of periodic, quasiperiodic, fully chaotic and intermittently chaotic dynamics.
VEGETATION PATTERN FORMATION IN A SEMI-ARID CLIMATE
Authors: DIJKSTRA HENK A.
Published: February 2012

A partial bifurcation diagram of a reaction–diffusion type model of two-dimensional vegetation patterns in a semi-arid climate is computed using numerical continuation techniques. In previous studies with this model, it has been shown that two positive feedbacks (the infiltration feedback and precipitation feedback) may influence the type of vegetation patterns which appear under a certain precipitation forcing. In this bifurcation study, first the case is considered where the infiltration feedback is the only positive feedback. The partial bifurcation diagram of the different steady states is more complicated than earlier model results have suggested and provides insight into how the pattern selection process takes place. Finally, it is shown that when the precipitation feedback is included, the bifurcation diagram is only shifted to smaller precipitation values.
A DYNAMICAL APPROACH TO STOCK MARKET FLUCTUATIONS
Authors: NICOLIS S. C. , SUMPTER D. J. T.
Published: February 2012

The recent turbulence on the world's stock markets has reinvigorated the attack on classical economic models of stock market fluctuations. The key problem is determining a dynamic model, which is consistent with observed fluctuations and which reflects investor behavior. Here, we use a novel equation-free approach developed in nonlinear dynamics literature to identify the salient statistical features of fluctuations of the Dow Jones Industrial Average over the past 80 years. We then develop a minimal dynamical model in the form of a stochastic differential equation involving both additive and multiplicative system-noise couplings, which captures these features and whose parameterization on a time scale of days can be used to capture market distributions up to a time scale of months. The terms in the model can be directly linked to "herding" behavior on the part of traders. However, we show that parameters in this model have changed over a number of decades producing different market regimes. This result partially explains how, during some periods of history, "classic" economic models may work well and at other periods "econo-physics" models prove better.
TESTING A PARTICLE FILTER TO RECONSTRUCT CLIMATE CHANGES OVER THE PAST CENTURIES
Authors: DUBINKINA SVETLANA , GOOSSE HUGUES , SALLAZ-DAMAZ YOANN , CRESPIN ELISABETH , CRUCIFIX MICHEL
Published: February 2012

We implement a data-assimilation method based on a particle filter in the coupled climate model LOVECLIM focusing on decadal to centennial time scales. Several tests are performed with particle filtering using pseudo-observations obtained from a twin experiment with the model, as well as using real-data observations over the last century. These tests demonstrate that it is possible to obtain a model output well correlated with the observations at the large scale at a reasonable cost.
TREATMENT OF THE ERROR DUE TO UNRESOLVED SCALES IN SEQUENTIAL DATA ASSIMILATION
Authors: CARRASSI ALBERTO , VANNITSEM STÉPHANE
Published: February 2012

In this paper, a method to account for model error due to unresolved scales in sequential data assimilation, is proposed. An equation for the model error covariance required in the extended Kalman filter update is derived along with an approximation suitable for application with large scale dynamics typical in environmental modeling. This approach is tested in the context of a low order chaotic dynamical system. The results show that the filter skill is significantly improved by implementing the proposed scheme for the treatment of the unresolved scales.
EMERGENCE OF MULTI-CLUSTER CONFIGURATIONS FROM ATTRACTIVE AND REPULSIVE INTERACTIONS
Authors: HA SEUNG-YEAL , JEONG EUNHEE , KANG JEONG-HAN , KANG KYUNGKEUN
Published: February 2012

We discuss a first-order Cucker–Smale-type consensus model with attractive and repulsive interactions and present upper and lower bound estimates on the number of asymptotic point-clusters depending on the relative ranges of interactions and coupling strength. When the number of agents approaches infinity, we introduce a scalar conservation law with a non-local flux for a macroscopic description. We show that the corresponding conservation law admits a classical solution for sufficiently smooth initial data, which illustrates the shock avoidance effect due to the non-locality of the interactions. We also study the dynamics of special Dirac-Comb-type solutions consisting of two and three point-clusters.
EFFECT OF SURFACE MODIFICATION ON STRUCTURAL, OPTICAL AND AMMONIA SENSING PROPERTIES OF INDIUM OXIDE FILMS
Authors: BAL AMANDEEP KAUR , BEDI R. K.
Published: February 2012

Indium oxide (In2O3) films have been prepared by thermal oxidation of pre-deposited indium films onto glass substrate kept at room temperature (35°C). These films were dipped into an aqueous solution (0.1 M) of lithium chloride (LiCl) and aluminum chloride (AlCl3) followed by being fired at 500°C. Based on X-ray diffraction results, it has been observed that pure and Li modified In2O3 films are polycrystalline in nature while Al modified In2O3 film has a prominent peak corresponding to 222 plane of In2O3 . Field emission scanning electron microscopy of pure film shows smaller grains which get transformed to bigger ones for Li modified In2O3 film. In case of Al modified In2O3 film agglomerated small grains are observed. This film also reveals the response of 60% for 100 ppm of ammonia vapors at room temperature. The transparency increased from 23–36% to 53–67% in visible region with Li modification of pure In2O3 film.
DETECTION OF THE SPATIAL CURVATURE EFFECTS THROUGH PHYSICAL PHENOMENA: THE NONLINEAR COHERENT STATES APPROACH
Authors: MAHDIFAR A. , ROKNIZADEH R. , NADERI M. H.
Published: February 2012

In this paper, by using the nonlinear coherent states approach, we find a relation between the geometric structure of the physical space and the geometry of the corresponding projective Hilbert space. To illustrate the approach, we explore the quantum transition probability and the geometric phase in the curved space.
PREPARATION AND INVESTIGATION OF OPTICAL, THERMAL, AND ELECTROCHEMICAL PROPERTIES OF Ag/Co NANOPARTICLES
Authors: PARANG Z. , KESHAVARZ A. , FARAHI S. , ELAHI S. M. , GHORANNEVISS M. , NASSERI A.
Published: February 2012

Ag/Co nanoparticles (NPs) were prepared by a two-step method. First, Ag NPs were synthesized by "Controlled Current Coulometry" (CCC) electrochemical method using a Pt rotating electrode. Then, Ag/Co core-shell NPs were prepared through the reduction method using Ag NPs as a core. Both steps were accomplished at room temperature. Techniques such as patterned X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed for the characterization of Ag/Co NPs. Optical properties of synthesized NPs were also investigated by UV-Vis spectroscopy. The absorption peak of Ag NPs was observed at ~400 nm wavelength and the peaks that were detected at 425 nm and 415 nm wavelengths reveal the formation of Ag/Co NPs. The core-shell structure of Ag/Co NPs was confirmed by thermal and electrochemical techniques. We also applied "Mie" theory to calculate the absorption cross-section band of synthesized Ag/Co NPs. Comparison between the results of optical properties and also those obtained from "Mie" theory showed good agreements.
EFFECTS OF PREPARATION PARAMETERS ON ONE-DIMENSIONAL CdS NANOSTRUCTURES BY DIPHENYLTHIOCARBAZONE-ASSISTED SOLVOTHERMAL METHOD
Authors: ZHOU JING , ZHAO GAOLING , SONG BIN , DONG WEIXIA , YANG JINJIAN , HAN GAORONG
Published: February 2012

One-dimensional (1D) single crystalline CdS nanostructures have been successfully synthesized via a diphenylthiocarbazone-assisted solvothermal route. The results revealed that the microstructure and optical absorption properties of 1D CdS nanostructures were temperature and time dependent owing to thermodynamically and kinetically controlled growth. Single crystalline CdS nanowires with a diameter of 80 nm and length of 20 μm were synthesized at 180°C for 96 h. At moderate temperature (180°C), the morphology of the products transformed from irregular short rods to uniform long rods as the reaction time prolonging in a kinetically controlled growth regime. Only nanorods were obtained at a temperature as low as 120°C even extending reaction time to 260 h due to thermodynamic limited growth. At high temperature (250°C in this system), the products were nanowires with larger diameter but lower aspect ratio since the growth rates on both lateral and axial directions were accelerated. Moreover, the optical absorption spectra revealed that the CdS nanowires showed a blue shift compared with bulk CdS. Two optical absorption peaks appeared due to the nanometer effect in the radial and lengthwise directions of CdS nanowires. The growth mechanism of 1D CdS nanostructures was discussed.
ANALYSIS OF DENDRITIC CELL STIMULATION UTILIZING A MULTI-FACETED NANOPOLYMER DELIVERY SYSTEM AND THE IMMUNE MODULATOR 1-METHYL TRYPTOPHAN
Authors: NIKITCZUK KEVIN P. , LATTIME EDMUND C. , SCHLOSS RENE S. , YARMUSH MARTIN L.
Published: February 2012

Dendritic cells (DCs) play a pivotal role in immune modulation. Therefore, understanding and regulating the mechanism of DC activation is paramount for functional optimization of any immunotherapy strategy. In particular, the paradoxical ability of DCs to secrete the immune suppressive enzyme indoleamine 2, 3-dioxygenase (IDO) and the suppressive cytokine IL-10 during the course of, and in response to, stimulation is of great interest. 1-Methyl-Tryptophan (1 MT) is a known inhibitor of IDO and has thus been administered in numerous in vitro and in vivo systems to block IDO activity. However, the effect 1 MT has on DCs beyond inhibiting IDO, especially in therapeutic models, has rarely been analyzed. In the current study, we have administered 1 MT via a nanopolymer-based delivery system in conjunction with an antigen (ovalbumin, OVA) and an adjuvant (CpG motif DNA) to determine both the effects of 1 MT on DCs and the resulting efficacy of the polymer-based treatments. 1 MT delivery alone, either via the polymer-based delivery vehicle or dissolved in solution, induced no significant change in DC activation as measured by surface expression of CD80, CD86, and MHCII and several secreted products such as IL-12. These same factors were upregulated however, when 1 MT was delivered in conjunction with OVA and CpG. Although soluble delivery of these components increased the levels of expression and secretion of key proteins, a differential effect of DC stimulation was seen as a result of the polymer delivery system. The T cell suppressive IL-10 secretion was lower with the polymer-based treatments and IL-12 immune-enhancing secretion was increased when 1 MT was supplemented into the polymer system. As a result, including 1 MT in the polymers along with OVA and CpG was seen to have additional effects on DC stimulation and was able to shift DCs to a state more indicative of inducing a Th1-type response.
PHOSPHOLIPID ASSEMBLY ON SUPERPARAMAGNETIC NANOPARTICLES FOR THERMORESPONSIVE DRUG DELIVERY APPLICATIONS
Authors: HUTH CHRISTOPHER , SHI DONGLU , WANG FENG , CARRAHAR DONALD , LIAN JIE , LU FENGYUAN , ZHANG JIAMING , EWING RODNEY C. , PAULETTI GIOVANNI M.
Published: February 2012

Thermoresponsive nanocomposites were prepared by immobilizing a 2–3 nm thick phospholipid layer on the surface of superparamagnetic Fe3O4 nanoparticles via high-affinity avidin/biotin interactions. Morphological and physicochemical surface properties were assessed using transmission electron microscopy, confocal laser scanning microscopy, differential scanning calorimetry, and attenuated total reflectance Fourier transform infrared spectroscopy. The zeta potential of Fe3O4 colloids in phosphate buffered saline (PBS) decreased from -23.6 to -5.0 mV as a consequence of phospholipid immobilization. Nevertheless, heating properties of these superparamagnetic nanoparticles within an alternating magnetic field were not significantly affected. Hyperthermia-relevant temperatures > 40°C were achieved within 10–15 min using a 7-mT magnetic field alternating at a frequency of 1 MHz. Loading of the surface-associated phospholipid layer with the hydrophobic dye dansylcadaverine was accomplished at an efficiency of 479 ng/mg Fe3O4 . Release of this drug surrogate was temperature-dependent, resulting in a 2.5-fold greater release rate when nanoparticles were exposed to a temperature above the experimentally determined melting temperature of 39.7°C. These data underline the feasibility of preparing novel, stimulus-induced drug delivery systems where payload release from a colloid-immobilized phospholipid assembly is triggered by hyperthermia.
Effect of an Upward and Downward Interface Dipole Langmuir–Blodgett Monolayer on Pentacene Organic Field-Effect Transistors: A Comparison Study
Authors: Ou-Yang Wei , Weis Martin , Manaka Takaaki , Iwamoto Mitsumasa
Published: February 2012

We studied carrier behaviors of pentacene organic field-effect transistors (OFETs) with an upward and a downward orientation dipole monolayer, inserted between the organic active layer and gate insulator by the Langmuir–Blodgett technique. The OFETs with an upward orientation of dipole monolayer showed large negative threshold voltage and high contact resistance compared with the reference OFETs without dipole monolayer, while the OFETs with a downward orientation dipole monolayer exhibited positive threshold voltage and low contact resistance. Based on the findings from this comparison study, we argued that using interface dipole monolayer is a useful way to design OFET performance.
Growth and Surface Structure of Thin Co Films on Au(001) Studied by Scanning Tunneling Microscopy
Authors: Kawagoe Takeshi , Miyamachi Toshio , Suga Shigemasa
Published: February 2012

We have studied the room-temperature growth of Co films on Au(001) substrate in the thickness range up to 3.4 monolayers (ML) and also studied the effects of annealing at 500 K. The surface morphology and structure at various Co coverages (θCo) were investigated in scanning tunneling microscopy (STM) and low-energy electron diffraction studies. As-grown Co films up to 3.4 ML thick show bcc structures with Co islands. Annealing at 500 K activates several diffusion mechanisms, inducing surface segregation of Au and phase separation between Au and Co. These mechanisms change the structure and surface morphology of the films significantly. Consequently, regular nanostructures aligned in the <100> direction and consisting of buried Co islands are formed and characteristic reconstruction of the Au(001) surface were observed on annealed Co films. From the observed STM height profile data we have inferred detailed surface and interface structures due to the large difference between the monolayer heights of the bcc Co(001) and fcc Au(001). In samples with θCo=3.4 ML we observed a regular network structure with the (2 ×1) reconstruction. The mechanism by which the buried Co islands form is discussed based on thermodynamic considerations.
The decreased expression of Beclin-1 correlates with progression to esophageal adenocarcinoma: the role of deoxycholic acid
Authors: Roesly Heather B. , Khan Mohammad R. , Chen Hwu Dau Rw , Hill Kimberly A. , Narendran Nirushan , Watts George S. , Chen Xiaoxin , Dvorak Katerina
Published: February 2012

Beclin-1 has a central role in the regulation of autophagy. Barrett's esophagus (BE) is associated with a significantly increased risk for the development of esophageal adenocarcinoma (EAC). In the current study, we evaluated the role of Beclin-1 and autophagy in the EAC. Biopsies obtained from patients with BE and EAC, tissues from a rat model of BE and EAC, and esophageal cell lines were evaluated for the expression of Beclin-1 by immunohistochemistry, immunoblotting, or RT-PCR. Since reflux of bile acids is important in EAC, we also evaluated the effect of exposure to deoxycholic acid (DCA) on autophagy and Beclin-1 expression. Beclin-1 expression was high in squamous epithelium and nondysplastic BE, whereas its expression was low in dysplastic BE and EAC. The same pattern of expression was observed in rat tissues and in esophageal cell lines. Normal esophageal epithelium and HET-1A cells (derived from normal squamous epithelium) show high levels of Beclin-1, but lower levels of Beclin-1 were found in BE and EAC cell lines (CP-A, CP-C, and OE33). Acute exposure to DCA led to increased Beclin-1 expression and increased autophagy as evaluated by electron microscopy and counting percentage of GFP-LC3-positive BE cells with punctate pattern. In contrast, chronic exposure to DCA did not result in the alteration of Beclin-1 levels or autophagy. In summary, these data suggest that autophagy is initially activated in response to bile acids, but chronic exposure to bile acids leads to decreased Beclin-1 expression and autophagy resistance.
Tuning of the ocular vestibular evoked myogenic potential to bone-conducted sound stimulation
Authors: Zhang Alexander S. , Govender Sendhil , Colebatch James G.
Published: February 2012

Ocular vestibular evoked myogenic potentials (oVEMPs) are a recently described clinical measure of the vestibulo-ocular reflex. Studies demonstrating differences in frequency tuning between air-conducted and bone-conducted (BC) oVEMPs suggest a separate vestibular (otolith) origin for each stimulus modality. In this study, 10 healthy subjects were stimulated with BC stimuli using a hand-held minishaker. Frequencies were tested in the range of 50–1,000 Hz using both a constant-force and constant-acceleration method. Subjects were stimulated at the mastoid process and the forehead. For constant-force stimulation at both sites, maximum acceleration occurred around 100 Hz, in differing axes. Both forms of stimulation had low-frequency peaks of oVEMP amplitudes (constant force: mastoid, 80–150 Hz; forehead, 50–125 Hz; constant acceleration: mastoid, 100–200 Hz; forehead, 80–150 Hz), for both sites of application, despite differences in the magnitude and direction of evoked head acceleration. For mastoid stimulation, ocular responses changed from out of phase to in phase for 400 Hz and above. Our results demonstrate that BC stimuli show tuning around 100 Hz, independent of stimulus site, that is not due to skull properties. The findings are consistent with an effect on a receptor with a resonance around 100 Hz, most likely the utricle.