bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Sphagnum-dominated peatlands in boreal continental Canada
Authors: Kuhry Peter , Nicholson Barbara J. , Gignac L. Dennis , Vitt Dale H. , Bayley Suzanne E.
Published: August 2009

Peat cores from five Sphagnum-dominated peatlands in boreal continental Canada were analyzed for plant macro fossils. Results indicate that peatland development was influenced both by local autogenic and regional climatic factors. The general direction in peatland development from rich fen to poor fen to bog can primarily be ascribed to internal processes, especially peat accumulation. Quantitative paleoenvironmental reconstructions based on fossil moss assemblages indicate that all five peatlands were initially dominated by brown mosses with inferred pHs of approximately 6.0, and a water table at 5–15 cm below the surface of the peatland. Subsequently, Sphagnum-dominated peatlands developed with pHs of 4.0–4.5 and a water table at 15–30 cm of depth. Chemical factors triggered a rapid transition from rich fen (pH > 6) to poor fen and bog (Ph < 5). The two most southerly peatlands are youngest, with basal dates of 4670 BP and 4230 BP. Sphagnum peat accumulation at these sites started at 2620 BP and 1790 BP, respectively. Two sites located at intermediate latitudes have basal dates of > 5140 BP and 5020 BP, while the development of Sphagnum-dominated ecosystems dates back to ≈ 3100 BP and 3710 BP, respectively. The most northerly site has the oldest basal date (> 7870 BP), and the oldest date for the initiation of Sphagnum peat accumulation (≈ 7000 BP). The younger age of the peat deposits in the four southern sites is due to warm and dry climatic conditions during the middle Holocene that prevented peatland development until after 6000 BP when the climate gradually became cooler and moister. Farther north the climate was cool and moist enough to allow peatland development during the early to middle Holocene. In three southern peatlands, the development into a Sphagnum-dominated ecosystem took > 2000 years, while at the more northerly sites Sphagnum became dominant after < 1500 years. Key words: Sphagnum, peatlands, boreal, Holocene, climate.
Effects of nitrogen fertilization on several woody and nonwoody boreal forest species
Authors: Nams Vilis O. , Folkard Nicholas F. G. , Smith James N. M.
Published: August 2009

The effects of three levels of fertilizer were tested on the growth of several woody and nonwoody plants from a boreal forest community in southwestern Yukon. The effects of fertilization were assessed by clipping ground layer vegetation and measuring twig growth at the end of the second summer. Over the 2 years of fertilization there were significant increases in growth over control levels for perennial grasses (Festuca altaica and Calamagrostis lapponica), two herbs (Epilobium angustifolium and Achillea millefolium), and two deciduous shrubs (Salix glauca and Betula glandulosa). However, the growth of white spruce trees (Picea glauca) increased only slightly in response to increasing nitrogen levels, and the evergreen dwarf shrub Arctostaphylos uva-ursi showed no response. Key words: fertilization, boreal forest, shrubs, grasses, herbs, nitrogen.
Ultrastructural and histochemical postfertilization megagametophyte and zygotic embryo development of white spruce (Picea glauca) emphasizing the deposition of seed storage products
Authors: Krasowski Marek J. , Owens John N.
Published: August 2009

Deposition of major storage substances in the megagametophyte and embryo of white spruce (Picea glauca (Moench) Voss) was studied ultrastructurally and histochemically during seed development. Lipid bodies appeared to be secreted by the smooth endoplasmic reticulum. In the megagametophyte they were deposited rapidly from the club-shaped embryo stage until the early organogenesis of the embryo. Major lipid accumulation in the embryo took place during rapid cotyledon development and simultaneously with the buildup of protein bodies. Formation of protein bodies in the megagametophyte and in the embryo was first detected approximately 6 and 29 days after fertilization, respectively. It is suggested that in the megagametophyte, this process proceeded by (i) deposition of amorphous protein clumps onto tonoplasts of subdividing vacuoles during early stages of protein body formation, (ii) fusion of small cytoplasmic vesicles possibly derived from the rough endoplasmic reticulum, and (iii) deposition of protein around dense, membrane-bound vesicles attached to tonoplasts. The third process was not observed in the embryo. During advanced formation, fusion of cytoplasmic vesicles into developing protein bodies was the only process observed in the megagametophyte and in the embryo. White spruce seed protein bodies contained a variable number of crystalloids and globoid cavities except in the embryo in which only single globoid cavities were observed. Key words: Picea, ultrastructure, histochemistry, megagametophyte, embryo, seed.
Phytotoxicity of AAL-toxin and other compounds produced by Alternaria alternata to jimsonweed (Datura stramonium)
Authors: Abbas Hamed K. , Vesonder R. F. , Boyette C. D. , Peterson S. W.
Published: August 2009

Nine isolates of Alternaria alternata were obtained from infected tomato (cv. Beefsteak) plants. Each isolate was grown on autoclaved rice medium and corn meal agar medium and evaluated for pathogenesis and phytotoxicity to jimsonweed plants. Only A. alternata SWSL 1 (NRRL 18822) caused lodging on 1-week-old jimsonweed plants when sprayed at a rate of 20 g of fungus-infested rice per 100 mL distilled water. The symptoms began within 24 to 48 h following inoculation, and all plants were dead after 96 h. Treatment of 2-week-old jimsonweed plants in the same manner affected growth only. No symptoms occurred when SWSL 1 spores from corn meal agar were applied to jimsonweed at a rate of 2 × 107 spores/mL, with or without dew. The filtrates of fungus-infested rice of the SWSL 1 isolate were found to contain the following phytotoxins: AAL-toxin (100 μg/g), tenuazonic acid (10 μg/g), and alternariol monomethyl ether (580 μg/g). Crude and cell-free filtrates and AAL-toxin (concentration 200 μg/mL) caused similar damage on excised leaves, characterized by soft rot diffusing from the point of inoculation along the veins, adaxially or abaxially to leaves. Alternariol monomethyl ether (concentration 800 μg/mL) and tenuazonic acid (concentration 420 μg/mL) applied to excised jimsonweed leaves caused no visible damage. In intact plants, symptoms resulting from the crude filtrate, cell-free filtrate, and the AAL-toxin were identical. A dose–response study of AAL-toxin on excised jimsonweed and black nightshade (Solanum nigrum L.) leaves showed effects at concentrations of 1.56 μg/mL and 0.01 μg/mL, respectively. This is the first report of phytotoxicity of AAL-toxin to these two weeds and it may have potential as a weed control agent. Key words: weed, natural products, solid media, fungi.
Age of the Grenville dyke swarm, Ontario–Quebec: implications for the timing of lapetan rifting
Authors: Kamo S. L. , Krogh T. E. , Kumarapeli P. S.
Published: August 2009

U–Pb baddeleyite and zircon ages for three diabase dykes from widely spaced localities within the Grenville dyke swarm indicate a single age of emplacement at [Formula: see text] Ma. The 700 km long Grenville dyke swarm, located in the southeastern part of the Canadian Shield, was emplaced syntectonically with the development of the Ottawa graben. This graben may represent a plume-generated lapetan failed arm that developed at the onset of the breakup of Laurentia. Other precisely dated lapetan rift-related units, such as the Callander Alkaline Complex and the Tibbit Hill Formation volcanic rocks, indicate a protracted 36 Ma period of rifting and magmatism prior to volcanism along this segment of the lapetan margin. The age of the Grenville dykes is the youngest in a progression of precisely dated mafic magmatic events from the 723 Ma Franklin dykes and sills to the 615 Ma Long Range dykes, along the northern and northeastern margins of Laurentia, respectively. Thus, the age for these dykes represents a key time marker for continental breakup that preceded the formation of the Iapetus ocean.
40Ar/39Ar and K–Ar age constraints on shear zone evolution, southern Taltson magmatic zone, northeastern Alberta
Authors: Plint H. E. , McDonough M. R.
Published: August 2009

New 40Ar/39Ar analyses of hornblende, muscovite, biotite, and K-feldspar constrain the timing of deformation and cooling of the southern Taltson magmatic zone, which underwent lower granulite to upper amphibolite grade deformation, in part synchronous with voluminous 1.99–1.92 Ga magmatism. New data are combined with existing K–Ar dates into a regional cooling framework to provide thermotemporal constraints on the deformational history. 40Ar/39Ar hornblende ages of ca. 1900 Ma are interpreted to record relatively rapid cooling following ductile thrusting on the Andrew Lake shear zone, and younger anatectic magmatism. These data, with published K–Ar and U–Pb data, support relatively rapid cooling of the Taltson magmatic zone from monazite closure temperature of 725 °C at ca. 1930 Ma to 525 °C at ca. 1900 Ma. Cooling rate estimates are about 7 °C/Ma, which suggests moderate exhumation rates during the high-grade part of the deformational history. A muscovite 40Ar/39Ar plateau age of 1803 ± 11 Ma is consistent with the mean muscovite K–Ar age of 1792 Ma, indicating regional cooling through about 350 °C at ca. 1800 Ma. 40Ar/39Ar ages from magmatic biotite of 1856 and 1799 Ma also suggest slow cooling during greenschist grade deformation, which can be no older than ca. 1860 Ma. A K-feldspar 40Ar/39Ar age of 1681 Ma provides a lower limit for the time of greenschist grade deformation. Cooling rate estimates during amphibolite to greenschist grade deformation are 1.75–2.25 °C/Ma.
Recent, tectonically induced, surficial stress-relief structures in the Ottawa–Hull area, Canada
Authors: Wallach Joe , Benn Keith , Rimando Roily
Published: August 2009

Contemporary reverse faults, marked by offset boreholes, were identified in two roadcuts, and recently formed pop-ups, which are surficial chevron folds, have been recognized in a quarry in the Ottawa-Hull area of Ontario and Quebec, Canada. Displacement directions of the hanging walls, marked by the offset boreholes, are commonly north-northeast to east-northeast, though one set shows displacement to the northwest. The pop-ups recorded during this investigation show average orientations of 120 and 063°. These are similar to the average trends of 136 and 074° documented in a previous study from a quarry about 20 km away. East-southeast- to southeast-trending pop-ups predominate in the two quarries and are kinematically compatible with most of the offset borehole directions recognized to date in the Ottawa-Hull area. Moreover, the quarry-floor pop-up trends in the Ottawa-Hull area are consistent with those of open field, lake bottom and other quarry-floor pop-ups in an area extending from the Miramichi region of New Brunswick into the east-central U.S.A. The compressional origin of the reverse faults and pop-ups, and the predominant orientations of those structures, are compatible with the current ambient stress field in eastern North America. This implies that both the displaced boreholes and quarry-floor pop-ups are products of that stress field, and, despite their presence in excavations, are tectonic in origin.
Monosomic analysis of leaf peroxidase Px0 and Px9 loci in hexaploid oats
Authors: Morikawa Toshinobu
Published: August 2009

Inheritance of the peroxidase isoenzymes of the flag leaf blade was examined by isoelectrofocusing in the hexaploid oats Avena byzantina cv. Kanota, Avena fatua ssp. compacta, and Avena sativa cv. Cherokee. Two independent peroxidase loci (Px0 and Px9) were detected in the F2 from the 'Kanota' × compacta cross. The Px0a derived from compacta expressed the highest peroxidase activity and was accompanied by a post-transcriptionally modified form or mozyme. A monosomic analysis of the Px0 and Px9 loci revealed that they were located on chromosomes 18 and 6, respectively. Phenotypic expression of the peroxidases varied in each genotye at the Px0 and Px9 loci. Phenotypes of the homozygote (Px0aPx0a) and the hemizygote (Px0a—) were similar to each other. The heterozygote (Px0aPx0b) had half the enzymatic activity of the others. Px9b of compacta was functional as a suppressor but that of 'Cherokee' was nonfunctional.Key words: monosomic analysis, peroxidase loci, isoenzyme, hexaploid oats.
The B chromosomes of Locusta migratoria. II. Effects on chiasma frequency
Authors: Viseras Esther , Salcedo F. Javier , Camacho Juan Pedro M.
Published: August 2009

The effects of accessory chromosomes of Locusta migratoria have been tested at intra- and inter-individual levels. Intraindividual analysis demonstrated that chiasma frequency of a cell is independent of the number of B-chromosomes that it contains. Interindividual analysis was done using males with a close genetic relationship (brother–brother and father–son) as well as males not showing such relationship. This analysis demonstrated the importance of both genetic and environmental factors in determining chiasma frequency. It was concluded that B chromosomes have no influence on this character.Key words: Locusta, B chromosomes, chiasma frequency.
Meiotic behaviour of the pollen mother cells in cultured anthers of rye excised at early meiotic prophase
Authors: Rueda J. , Vázquez A. M.
Published: August 2009

Anthers of rye were excised during leptotene and zygotene and cultured in vitro on media with and without indole-3-acetic acid to study the behaviour of pollen mother cells during meiosis. Percentages of pollen sacs in which pollen mother cells continued meiosis increased from approximately 20% to 60–70% when anthers were excised at early and late leptotene. The highest values were about 90% when the excision was during zygotene. The results were similar on both media. The timing of pollen mother cells through meiosis on the hormone-free medium was similar to that described in vivo. The mean numbers of chiasmata per cell at metaphase I from the cultured pollen sacs were compared with those from a random population of pollen sacs grown in the field. A significant decrease was observed when anthers were excised during leptotene and cultured on both media, as well as when anthers were excised at early zygotene and cultured on the hormone-supplemented medium. We concluded that at early zygotene there are processes related to chiasma formation that seem to be influenced by hormone balance.Key words: Secale cereale, anther culture, meiosis development, chiasma formation, indole-3-acetic acid.
Transformation of Drosophila melanogaster with a suppressor tRNA gene from Schizosaccharomyces pombe
Authors: Molnar Charles M. , Reece Tove , Williams James A. , Bell John B.
Published: August 2009

P-element mediated transformation was utilized to introduce a suppressor tRNA gene [Formula: see text] from Schizosaccharomyces pombe into Drosophila melanogaster. Thirteen independently transformed lines were characterized as to the number and cytological locations of the transposons. It was ascertained that the suppressor tRNA gene of interest was introduced into each transformed strain. The helper P element used (pπ25.1) allows further transposition to occur, and it was determined that from one to seven copies of the heterologous [Formula: see text] gene per strain were present among the respective transformed strains. The number of transposons per transformed line was established by in situ hybridization to salivary gland chromosomes as well as by Southern hybridization analyses and there was good agreement in the totals determined by these two techniques.Key words: Drosophila, Schizosaccharomyces, tRNA suppressor, transformation, transposon.
ON SOME ELECTRICAL AND MAGNETIC PROPERTIES OF METALLIC SOLID SOLUTIONS
Authors: Friedel J.
Published: August 2009

The resistivity, thermoelectric power, and magnetic susceptibility of metallic solid solutions at room temperature are reviewed, and their relation with their electronic structure emphasized. The special properties of transitional impurities are related to the emptying of their d shells.
REMARKS ON THE ANOMALOUS BEHAVIOR OF ALLOYS CONTAINING TRACES OF MANGANESE OR SIMILAR ELEMENTS
Authors: Gorter C. J. , Berg G. J. van den , Nobel J. de
Published: August 2009

The anomalous behavior of alloys containing traces of manganese and similar elements is rapidly reviewed as to electrical conductivity, magnetoresistance, susceptibility, magnetic resonances, thermoelectricity, specific heat, thermal conductivity, and Hall effect. Special reference is given to recent data obtained in Leyden. It is argued that, while the rapid decrease of the resistance sometimes occurring at very low temperatures apparently must be attributed to some kind of antiferromagnetic alignment, the resistance minimum, as well as the anomalies in thermoelectricity and the Hall effect, might be due to gaps at the crystalline boundaries.
NUCLEAR MAGNETIC RESONANCE AND ELECTRONIC STRUCTURE OF CONDUCTORS
Authors: Bloembergen N.
Published: August 2009

The information about electron wave functions and band structures obtainable from nuclear magnetic resonance experiments in conductors is reviewed. The isotropic and anisotropic metallic shift, the relaxation time, isotropic and anisotropic spin exchange coupling, and quadrupole interactions are discussed. The variation of these effects as a function of pressure, temperature, and alloy composition is described. Some recent results for semiconductors and superconductors are included in the discussion.
IMPEDANCE MEASUREMENTS ON PZT ANDLa0.75Bi3.25Ti3O12CERAMICS
Authors: PRASAD N. V. , SUBRAHMANYAM J. , NARAYANA MURTY P. , KARMAKAR S. , GUPTA S. M.
Published: August 2009

Impedance measurements were made on technological important ferroelectric ceramics, namely PZT and La0.75Bi3.25Ti3O12(BLT), in the frequency range of 100 Hz to 1 MHz, from room temperature to 500°C. Combined impedance and modulus spectroscopic analysis along with the detailed conductivity (ac and dc) data was used to understand the heterogeneity of the ceramics and the results were corroborated with temperature coefficient of dc-conductivity (figure of merit) data for the further understanding. AC-conductivity plots against frequency at different temperatures for PZT and BLT suggest the response of obeying Jonscher's and modified Jonscher's law, respectively.
MEMORABILITY OF ALTERNATIVE PASSWORD SYSTEMS
Authors: OSTOJIC P. , PHILLIPS J. G.
Published: August 2009

Randomly generated alphanumeric passwords are widely used to restrict access to computer networks but are readily forgotten, resulting in costs to both organizations and users. In order to address this, there is a need to develop and evaluate new forms of memorable passwords. Drawing on memory research and the importance of meaning, the efficacy of three alternative "password" systems having varying degrees of personal meaning were compared with the more traditional but personally meaningless randomly generated alphanumeric passwords. Twenty experienced computer users self-generated four-string variable passwords based on alphanumerics, symbols of personal meaning and faces. Additionally, participants were assigned a meaningless, randomly generated four-character alphanumeric password. Password memorability was measured in terms of acquisition (number of trials/time to criterion), retention (from forgetting functions) and retrieval (time to recall/recognize the passwords). Meaning was found to assist memorability and a mediating effect of familiarity was also observed. Contrary to expectation, self-generated, meaningful symbol-based passwords were not the best remembered of the password types studied but may still be a viable overall alternative.
DYNAMIC POSITIONAL WARPING: DYNAMIC TIME WARPING FOR ONLINE HANDWRITING
Authors: CHANG WON-DU , SHIN JUNGPIL
Published: August 2009

This paper addresses the problem of dynamic time warping (DTW) causing unintended matching correspondences when it is employed for online two-dimensional (2D) handwriting signals, and proposes the concept of dynamic positional warping (DPW) in conjunction with DTW for online handwriting matching problems. The proposed DPW allows subsignal translations without any additional costs when their starting points are matched to other points through the matching process. Because the movement of subsignals is cost-free, except for the distance between the two starting points, an adequate movement — finding and matching similar subsignals — could significantly reduce the matching cost. This feature causes a tendency to match with the least amount of subsignal movement in the result. In order to evaluate the proposed method of solving this problem, two experiments were conducted: an accuracy test for matching similar handwriting and a utility test for signature verification. For the former, we proposed the new concept of ideal matching between two handwriting signals using the affine transformation; the results of this test verified the superiority of the proposed DPW over conventional methods in reducing matching errors. Further, DPW significantly outperformed the conventional methods in the latter test.
EXPERIMENTAL ANALYSIS OF INDIVIDUALITY OF JAPANESE HANDWRITING
Authors: UEDA KATSUHIKO , MATSUO KEN'ICHI , SCHWID BONNIE L.
Published: August 2009

A handwriting examination to determine the writer (writer verification and writer identification) is based upon the hypothesis that each person has characteristic handwriting that is distinct from the handwriting of other individuals. This hypothesis has been accepted empirically through many case studies. However, this hypothesis must be established with scientific and quantitative rigor in order to increase its admissibility as forensic evidence. This paper describes the results of a quantitative investigation into individuality of Japanese handwriting. The authors investigated the individuality (consistency and discriminability) of normal Japanese handwriting using variation entropy and writer verification algorithms. We also compared these results with the analysis results of Japanese signatures that we investigated previously. The authors discuss the differences of individuality between normal handwriting and signatures. Individuality of normal handwriting becomes noticeable as the number of strokes increases, and varies with the complexity of the character class. Although individuality of both normal handwriting and signatures also depends on the writer, this is more noticeable for signatures. It is important that these facts are considered in actual forensic analysis of Japanese handwriting.
A STUDY ON THE SUDDEN DEATH AND SUDDEN BIRTH OF ENTANGLEMENT IN AN OPEN SYSTEM
Authors: ZHANG YING-JIE , XIA YUN-JIE
Published: August 2009

In this paper, we consider the entanglement dynamics of two cavities interacting with independent reservoirs. When the cavity entanglement suddenly disappeared, the reservoir entanglement suddenly and necessarily appears. We study the effect of purity of initial entangled state of two cavities on the entanglement evolution, and acquire that the purity of initial entangled state of two cavities can control the apparition time of the entanglement sudden death and the entanglement sudden birth. Also, we find that the conditions on the apparition of the entanglement sudden death and the entanglement sudden birth can be generalized when the initial entangled state of cavities is not pure, which is a complement to the result in the paper [Phys. Rev. Lett.101 (2008) 080503] for the pure case.
MINIMIZATION AND OPTIMIZATION OF REVERSIBLE BCD-FULL ADDER/SUBTRACTOR USING GENETIC ALGORITHM AND DON'T CARE CONCEPT
Authors: MOHAMMADI MAJID , HAGHPARAST MAJID , ESHGHI MOHAMMAD , NAVI KEIVAN
Published: August 2009

Reversible logic and binary coded decimal (BCD) arithmetic are two concerning subjects of hardware. This paper proposes a modular synthesis method to realize a reversible BCD-full adder (BCD-FA) and subtractor circuit. We propose three approaches to design and optimize all parts of a BCD-FA circuit using genetic algorithm and don't care concept. Our first approach is based on the Hafiz's work, and the second one is based on the whole BCD-FA circuit design. In the third approach, a binary to BCD converter is presented. Optimizations are done in terms of number of gates, number of garbage inputs/outputs, and the quantum cost of the circuit. We present four designs for BCD-FA with four different goals: minimum garbage inputs/outputs, minimum quantum cost, minimum number of gates, and optimum circuit in terms of all the above parameters.
THERMAL ENTANGLEMENT IN THE TWO-QUBIT SYSTEMS CONSTRUCTED FROM THE YANG-BAXTER $\check{R}$-MATRIX
Authors: SUN CHUNFANG , HU TAOTAO , WANG GANGCHENG , WU CHUNFENG , XUE KANG
Published: August 2009

Some new Hamiltonians are constructed via the unitary Yang-Baxter matrices [Formula: see text] acting on a Hamiltonian H0 which describes nearest spin-spin interaction. By the concept of concurrence, we explore the thermal entanglement of these systems. We find that the interaction of z-component of two neighboring spins g has great influences on the thermal entanglement. It not only influences the critical temperature Tc, but can also influence the critical magnetic field Bc.
ENTANGLEMENT IN ONE-AND TWO-DIMENSIONAL ANDERSON MODELS WITH LONG-RANGE CORRELATED-DISORDER
Authors: GUO Z. Z. , XUAN Z. G. , ZHANG Y. S. , WU XIAOWEI
Published: August 2009

The ground state entanglement in one- and two-dimensional Anderson models are studied with consideration of the long-range correlation effects and using the measures of concurrence and von Neumann entropy. We compare the effects of the long-range power-law correlation for the on-site energies on entanglement with the uncorrelated cases. We demonstrate the existence of the band structure of the entanglement. The intraband and interband jumping phenomena of the entanglement are also reported and explained to as the localization-delocalization transition of the system. We also demonstrated the difference between the results of one- and two-dimensions. Our results show that the correlation of the on-site energies increases the entanglement.
NATURAL METRIC FOR QUANTUM INFORMATION THEORY
Authors: LAMBERTI P. W. , PORTESI M. , SPARACINO J.
Published: August 2009

We study in detail a very natural metric for quantum states. This new proposal has two basic ingredients: entropy and purification. The metric for two mixed states is defined as the square root of the entropy of the average of representative purifications of those states. Some basic properties are analyzed and its relation to other distances is investigated. As an illustrative application, the proposed metric is evaluated for one-qubit mixed states.
THERMAL ENTANGLEMENT OF A TWO-QUTRIT XXZ SPIN CHAIN WITH DZIALOSHISKI-MORIYA INTERACTION
Authors: MA XIAO SAN
Published: August 2009

The effect of Dzialoshiski-Moriya (DM) interaction and anisotropy on the thermal entanglement of a two-qutrit XXZ spin chain is investigated. Our analysis implies that the DM interaction and weak anisotropy can enhance the thermal entanglement to a maximum value while the strong anisotropy plays a positive role in shrinking thermal entanglement. Furthermore, we find that the entanglement evolution in terms of anisotropy is sensitive to weak anisotropy.
CONSTRUCTIONS OF SUBSYSTEM CODES OVER FINITE FIELDS
Authors: ALY SALAH A. , KLAPPENECKER ANDREAS
Published: August 2009

Subsystem codes protect quantum information by encoding it in a tensor factor of a subspace of the physical state space. They generalize all major quantum error protection schemes, and therefore are especially versatile. This paper introduces numerous constructions of subsystem codes. It is shown how one can derive subsystem codes from classical cyclic codes. Methods to trade the dimensions of subsystem and co-subsystem are introduced that maintain or improve the minimum distance. As a consequence, many optimal subsystem codes are obtained. Furthermore, it is shown how given subsystem codes can be extended, shortened, or combined to yield new subsystem codes. These subsystem code constructions are used to derive tables of upper and lower bounds on the subsystem code parameters.
SYMMETRIC AND PROBABILISTIC MULTIPARTY REMOTE STATE PREPARATION VIA THE POSITIVE-OPERATOR-VALUED MEASURE
Authors: LIU YI-MIN , WANG ZHANG-YIN , LIU XIAN-SONG , ZHANG ZHAN-JUN
Published: August 2009

We present a tripartite scheme for a preparer to remotely prepare an arbitrary single-qubit state in either distant ministrant's place by using a GHZ-type state. After the preparer's single-qubit state projective measurement, by performing a proper positive operator-valued measure, one ministrant can construct the preparer's state in a probabilistic manner with the other ministrant's assistance. Furthermore, we show that the remote state preparation can be achieved with a higher probability provided that the prepared state belongs to two special ensembles. Finally, we sketch the generalization of the tripartite scheme to a multiparty case.
COMBINATORIAL CONSTRUCTION OF LINEAR QUANTUM CODES FROM QUATERNARY BCH CODES
Authors: LI RUIHU , XU ZONGBEN
Published: August 2009

Classical BCH codes that contain their (Euclidean or Hermitian) dual codes can be used to construct quantum stabilizer codes. But for given restricted length n, good quantum BCH codes are very sparse. In this paper, by puncturing and pasting check matrices of Hermitian dual containing BCH codes over the quaternary field, we construct many linear quantum codes with good parameters, and some of them have parameters exceeding the finite Gilbert-Varshamov bound for stabilizer quantum codes.
VULNERABILITY OF "A NOVEL PROTOCOL-AUTHENTICATION ALGORITHM RULING OUT A MAN-IN-THE-MIDDLE ATTACK IN QUANTUM CRYPTOGRAPHY"
Authors: ABIDIN AYSAJAN , LARSSON JAN-Å KE
Published: August 2009

In this paper, we review and comment on "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in quantum cryptography" [M. Peev et al., Int. J. Quant. Inf.3 (2005) 225]. In particular, we point out that the proposed primitive is not secure when used in a generic protocol, and needs additional authenticating properties of the surrounding quantum-cryptographic protocol.
Listeria monocytogenesMembrane Trafficking and Lifestyle: The Exception or the Rule?
Authors: Pizarro-Cerdá Javier , Cossart Pascale
Published: August 2009

Listeria monocytogenes is an intracellular bacterial pathogen that promotes its internalization within nonprofessional phagocytes by interacting with specific host cell receptors. L. monocytogenes resides transiently in a membrane-bound compartment before escaping into the host cell cytosol where bacterial proliferation takes place. Actin-based motility then promotes cell-to-cell pathogen spread. Extensive studies on cytoskeleton rearrangements, membrane trafficking, and other events have established this microorganism as an archetype of cellular function subversion for intracellular parasitism. Here we discuss the most significant membrane trafficking pathways hijacked by L. monocytogenes during the host cell infection process and compare them to those of other intracellular pathogens, in particular Shigella flexneri, Salmonella enterica, and Mycobacterium tuberculosis.
PI3K integrates the effects of insulin and leptin on large-conductance Ca2+-activated K+ channels in neuropeptide Y neurons of the hypothalamic arcuate nucleus
Authors: Yang Meng-Jie , Wang Fang , Wang Jiang-Hua , Wu Wen-Ning , Hu Zhuang-Li , Cheng Jin , Yu Dan-Fang , Long Li-Hong , Fu Hui , Xie Na , Chen Jian-Guo
Published: August 2009

The adipocyte-derived hormone leptin and the pancreatic β-cell-derived hormone insulin function as afferent signals to the hypothalamus in an endocrine feedback loop that regulates body adiposity. They act in hypothalamic centers to modulate the function of specific neuronal subtypes, such as neuropeptide Y (NPY) neurons, by modifying neuronal electrical activity. To investigate the intrinsic activity of these neurons and their responses to insulin and leptin, we used a combination of morphological features and immunocytochemical technique to identify the NPY neurons of hypothalamic arcuate nucleus (ARC) and record whole cell large-conductance Ca2+-activated potassium (BK) currents on them. We found that both of the hormones increase the peak amplitude of BK currents, shifting the steady-state activation curve to the left. The effect of both insulin and leptin can be prevented by pretreatment with inhibitors of tyrosine kinase and phosphatidylinositol 3-kinase (PI3K) but not MAPK. These data indicate that PI3K-mediated signals are the common regulators of BK channels by insulin and leptin and mediated the two hormones' identical activatory effects on ARC NPY neurons. The effect of insulin and leptin together was similar to that of insulin or leptin alone, and leptin or insulin pretreatment did not lead to insulin- or leptin-sensitizing effects, respectively. These intracellular signaling mechanisms may play key roles in regulating ARC NPY neuron activity and physiological processes such as the control of food intake and body weight, which are under the combined control of insulin and leptin.
Minimal model assessment of hepatic insulin extraction during an oral test from standard insulin kinetic parameters
Authors: Campioni M. , Toffolo G. , Basu R. , Rizza R. A. , Cobelli C.
Published: August 2009

In this article, a first aim was to develop a minimal modeling approach to noninvasively assess hepatic insulin extraction in 204 healthy subjects studied with a standard meal by coupling the already available meal C-peptide minimal model with a new insulin model. The ingredients of this model are posthepatic IDR, which in turn is described in terms of pancreatic ISR and hepatic insulin extraction HE, and a linear monocompartmental model of insulin kinetics. Even if ISR is provided by the C-peptide minimal model, the simultaneous assessment of HE and insulin kinetics is critical, since compensations may arise between parameters describing these two processes. Therefore, as a second aim of this study, a method was developed to predict standard values of insulin kinetic parameters in an individual on the basis of the individual's anthropometric characteristics. The statistical analysis, based on linear regression of insulin kinetic parameters estimated from IM-IVGTT data performed on the same subjects, demonstrated that insulin kinetic parameters can be accurately predicted from age and body surface area. Once kinetic parameters of the new insulin model were fixed to these values, HE profile and indexes during a meal were reliably estimated in each individual, indicating a significant suppression during the meal since the overall index of HE, equal to 60 ± 1% in the basal state, is reduced to 40 ± 1% during a meal. However, standard parameters provide an approximation of the individual one; thus, the third aim was to define the impact on estimated indexes of using standard instead of individually estimated values. Our results showed that the 25% uncertainty affecting as an average insulin kinetic parameters of an individual, when they are predicted from age and body surface area, translates into a similar relative uncertainty in the individual's hepatic insulin extraction indexes.
Long-Lasting Context Dependence Constrains Neural Encoding Models in Rodent Auditory Cortex
Authors: Asari Hiroki , Zador Anthony M.
Published: August 2009

Acoustic processing requires integration over time. We have used in vivo intracellular recording to measure neuronal integration times in anesthetized rats. Using natural sounds and other stimuli, we found that synaptic inputs to auditory cortical neurons showed a rather long context dependence, up to ≥4 s (τ ∼ 1 s), even though sound-evoked excitatory and inhibitory conductances per se rarely lasted ≳100 ms. Thalamic neurons showed only a much faster form of adaptation with a decay constant τ <100 ms, indicating that the long-lasting form originated from presynaptic mechanisms in the cortex, such as synaptic depression. Restricting knowledge of the stimulus history to only a few hundred milliseconds reduced the predictable response component to about half that of the optimal infinite-history model. Our results demonstrate the importance of long-range temporal effects in auditory cortex and suggest a potential neural substrate for auditory processing that requires integration over timescales of seconds or longer, such as stream segregation.
Coding of Repetitive Transients by Auditory Cortex on Heschl's Gyrus
Authors: Brugge John F. , Nourski Kirill V. , Oya Hiroyuki , Reale Richard A. , Kawasaki Hiroto , Steinschneider Mitchell , Howard Matthew A.
Published: August 2009

The capacity of auditory cortex on Heschl's gyrus (HG) to encode repetitive transients was studied in human patients undergoing surgical evaluation for medically intractable epilepsy. Multicontact depth electrodes were chronically implanted in gray matter of HG. Bilaterally presented stimuli were click trains varying in rate from 4 to 200 Hz. Averaged evoked potentials (AEPs) and event-related band power (ERBP), computed from responses at each of 14 recording sites, identified two auditory fields. A core field, which occupies posteromedial HG, was characterized by a robust polyphasic AEP on which could be superimposed a frequency following response (FFR). The FFR was prominent at click rates below ∼50 Hz, decreased rapidly as click rate was increased, but could reliably be detected at click rates as high as 200 Hz. These data are strikingly similar to those obtained by others in the monkey under essentially the same stimulus conditions, indicating that mechanisms underlying temporal processing in the auditory core may be highly conserved across primate species. ERBP, which reflects increases or decreases of both phase-locked and non–phase-locked power within given frequency bands, showed stimulus-related increases in gamma band frequencies as high as 250 Hz. The AEPs recorded in a belt field anterolateral to the core were typically of low amplitude, showing little or no evidence of short-latency waves or an FFR, even at the lowest click rates used. The non–phase-locked component of the response extracted from the ERBP showed a robust, long-latency response occurring here in response to the highest click rates in the series.
Gap-Junction Proteins in Retinal Development: New Roles for the “Nexus”
Authors: Cook Jeremy E. , Becker David L.
Published: August 2009

Gap-junction channels, the cytoplasmic proteins that associate with them, and the transcriptional networks that regulate them are increasingly being viewed as critical communications hubs for cell signaling in health and disease. As a result, the term “nexus,” which was the original structural name for these focal intercellular links, is coming back into use with new proteomic and transcriptomic meanings. The retina is better understood than any other part of the vertebrate central nervous system in respect of its developmental patterning, its diverse neuronal types and circuits, and the emergence of its definitive structure-function correlations. Thus, studies of the junctional and nonjunctional nexus roles of gap-junction proteins in coordinating retinal development should throw useful light on cell signaling in other developing nervous tissues.
Engineering Proteins for Custom Inhibition of CaVChannels
Authors: Xu Xianghua , Colecraft Henry M.
Published: August 2009

The influx of Ca2+ions through voltage-dependent calcium (CaV) channels links electrical signals to physiological responses in all excitable cells. Not surprisingly, blocking CaVchannel activity is a powerful method to regulate the function of excitable cells, and this is exploited for both physiological and therapeutic benefit. Nevertheless, the full potential for CaVchannel inhibition is not being realized by currently available small-molecule blockers or second-messenger modulators due to limitations in targeting them either to defined groups of cells in an organism or to distinct subcellular regions within a single cell. Here, we review early efforts to engineer protein molecule blockers of CaVchannels to fill this crucial niche. This technology would greatly expand the toolbox available to physiologists studying the biology of excitable cells at the cellular and systems level.
Molecular Mechanisms of Ischemic Cerebral Edema: Role of Electroneutral Ion Transport
Authors: Kahle Kristopher T. , Simard J. Marc , Staley Kevin J. , Nahed Brian V. , Jones Pamela S. , Sun Dandan
Published: August 2009

The brain achieves homeostasis of its intracellular and extracellular fluids by precisely regulating the transport of solute and water across its major cellular barriers: endothelia of the blood-brain barrier (BBB), choroid plexus epithelia, and neuroglial cell membranes. Cerebral edema, the pathological accumulation of fluid in the brain’s intracellular and extracellular spaces, is a major cause of morbidity and mortality following stroke and other forms of ischemic brain injury. Until recently, mechanisms of cerebral edema formation have been obscure; consequently, its treatment has been empiric and suboptimal. Here, we provide a paradigm for understanding ischemic cerebral edema, showing that its molecular pathogenesis is a complex yet step-wise process that results largely from impaired astrocytic cell volume regulation and permeability alterations in the cerebral microvasculature, both of which arise from pathological changes in the activities of specific ion channels and transporters. Recent data has implicated the bumetanide-sensitive NKCC1, an electroneutral cotransporter expressed in astrocytes and the BBB, in cerebral edema formation in several different rodent models of stroke. Pharmacological inhibition or genetic deficiency of NKCC1 decreases ischemia-induced cell swelling, BBB breakdown, cerebral edema, and neurotoxicity. Combination pharmacological strategies that include NKCC1 as a target might thus prove beneficial for the treatment of ischemic, and potentially other types of, cerebral edema.
The "Equation missing" Solutions of the Series-Like Iterative Equation with Variable Coefficients
Authors: Mi Yuzhen , Li Xiaopei , Ma Ling
Published: August 2009

By constructing a structure operator quite different from that ofZhang and Baker (2000) and using the Schauder fixed point theory, the existence and uniqueness of the "Equation missing" solutions of the series-like iterative equations with variable coefficients are discussed.
Fabrication of TiO2 Nanotube Thin Films and Their Gas Sensing Properties
Authors: Li Yongxiang , Yu Xiaofeng , Yang Qunbao
Published: August 2009

The fabrication process and the growth mechanism of titanium/titania nanotubes prepared by anodization process is reviewed, and their applications in the fields of dye sensitized solar cells, photocatalysts, electrochromic devices, gas sensors, and biomaterials are presented. The anodization of Ti thin films on different substrates and the growth process of anodic titanium oxide are described using the current‐time curves. Special attention is paid on the influences of the initial film smoothness on the resulted nanoporous morphologies. The “threshold barrier layer thickness model” is used to discuss the growth mechanism. As a case study for gas sensing, anodized highly ordered TiO2 nanotube arrays and nanoporous thin films that show porous surface with an average diameter of 25 nm and interpore distance of 40 nm were prepared. Gas sensors based on such nanotube arrays and nanoporous thin films were fabricated, and their sensing properties were investigated. Excellent H2 gas sensing properties were obtained for sensors prepared from these highly ordered TiO2 nanotube arrays, which present stable response even at a low operating temperature of 90°C. Based on our experimental results, “H‐induced O2− desorption” mechanism was used for explaining the hydrogen gas sensing mechanism.
Fixed Point Theorems for Random Lowersemi-continuous Mappings
Authors: Fierro Raúl , Martínez Carlos , Morales Claudio H.
Published: August 2009

We prove a general principle in Random Fixed Point Theory by introducing a condition named ("Equation missing") which was inspired by some of Petryshyn's work, and then we apply our result to prove some random fixed points theorems, including generalizations of some Bharucha-Reid theorems.
On Fuzzy Soft Sets
Authors: Ahmad B. , Kharal Athar
Published: August 2009

We further contribute to the properties of fuzzy soft sets as defined and studied in the work of Maji et al. ( 2001), Roy and Maji (2007), and Yang et al. (2007) and support them with examples and counterexamples. We improve Proposition 3.3 by Maji et al., (2001). Finally we define arbitrary fuzzy soft union and fuzzy soft intersection and prove DeMorgan Inclusions and DeMorgan Laws in Fuzzy Soft Set Theory.
Antibacterial Activity of Some Lactic Acid Bacteria Isolated from an Algerian Dairy Product
Authors: Mezaini Abdelkader , Chihib Nour-Eddine , Dilmi Bouras Abdelkader , Nedjar-Arroume Naima , Hornez Jean Pierre
Published: August 2009

In the present study, the antibacterial effect of 20 lactic acid bacteria isolates from a traditional cheese was investigated. 6 isolates showed antibacterial effect against Gram positive bacteria.Streptococcus thermophilusT2 strain showed the wide inhibitory spectrum against the Gram positive bacteria. Growth and bacteriocin production profiles showed that the maximal bacteriocin production, byS. thermophilusT2 cells, was measured by the end of the late-log phase (90 AUml−1) with a bacteriocine production rate of 9.3 (AUml−1)h−1. In addition, our findings showed that the bacteriocin, produced byS. thermophilusT2, was stable over a wide pH range (4–8); this indicates that such bacteriocin may be useful in acidic as well as nonacidic food. This preliminarily work shows the potential application of autochthonous lactic acid bacteria to improve safety of traditional fermented food.
Classification of Oncologic Data with Genetic Programming
Authors: Vanneschi Leonardo , Archetti Francesco , Castelli Mauro , Giordani Ilaria
Published: August 2009

Discovering the models explaining the hidden relationship between genetic material and tumor pathologies is one of the most important open challenges in biology and medicine. Given the large amount of data made available by the DNA Microarray technique, Machine Learning is becoming a popular tool for this kind of investigations. In the last few years, we have been particularly involved in the study of Genetic Programming for mining large sets of biomedical data. In this paper, we present a comparison between four variants of Genetic Programming for the classification of two different oncologic datasets: the first one contains data from healthy colon tissues and colon tissues affected by cancer; the second one contains data from patients affected by two kinds of leukemia (acute myeloid leukemia and acute lymphoblastic leukemia). We report experimental results obtained using two different fitness criteria: the receiver operating characteristic and the percentage of correctly classified instances. These results, and their comparison with the ones obtained by three nonevolutionary Machine Learning methods (Support Vector Machines, MultiBoosting, and Random Forests) on the same data, seem to hint that Genetic Programming is a promising technique for this kind of classification.