Extra Poles Research Articles

The effect of oral articulation on the acoustic characteristics of nasalized vowels

To study the acoustic characteristics of nasalized vowels, the effects of velopharyngeal opening and oral articulation are considered. Based on vocal tract area functions for one American English speaker, spectral evolutions for the nasalization of three English vowels /a/, /i/, and /u/ were studied by simulating transfer functions for vowels with only velar movement, and for different nasal consonant-vowel utterances, which include both velar and oral movements. Simulations indicate extra nasal spectral poles and zeros and oral formant shifts as a result of the velopharyngeal opening and oral movements, respectively. In this sense, if oral articulation is coordinated with velar movement in such a way that nasal acoustic features are prominently attenuated, corresponding compensatory articulation can be developed to reduce hypernasality. This may be realized by (1) adjusting the articulatory placement for isolated nasalized vowels or by (2) changing the relative timing of coarticulatory movements for dynamic speech. The results demonstrate the effect of oral articulation on the acoustics of nasalized vowels. This effect allows oral articulation to compensate for velopharyngeal dysfunction, which may involve a constellation of speech production disorders resulting from anomalous velopharyngeal closure and which is usually accompanied by hypernasality and nasal emission of air.

A NUP98-positive acute myeloid leukemia with a t(11;12)(p15;q13) without HOXC cluster gene involvement

We report a case of adult acute myeloid leukemia with a new t(11;12)(p15;q13) underlying a NUP98 rearrangement without HOXC cluster gene involvement. We designed a specific double-color double-fusion FISH assay to discriminate between this t(11;12)(p15;q13) and those producing NUP98-HOXC11 or NUP98-HOXC13. Our fluorescence in situ hybridization (FISH) showed that putative candidate partners mapping 600 kilobases centromeric to HOXC were RARG (retinoic acid receptor γ), MFSD5 (major facilitator superfamily domain containing 5), and ESPL1 (extra spindle pole bodies homolog 1). It is noteworthy that so far only ESPL1 has been implicated in human cancers. This FISH assay is useful for diagnostic screening of NUP98-positive leukemias.

Double excitations in finite systems

Time-dependent density-functional theory (TDDFT) is widely used in the study of linear response properties of finite systems. However, there are difficulties in properly describing excited states, which have double- and higher-excitation characters, which are particularly important in molecules with an open-shell ground state. These states would be described if the exact TDDFT kernel were used; however, within the adiabatic approximation to the exchange-correlation (xc) kernel, the calculated excitation energies have a strict single-excitation character and are fewer than the real ones. A frequency-dependent xc kernel could create extra poles in the response function, which would describe states with a multiple-excitation character. We introduce a frequency-dependent xc kernel, which can reproduce, within TDDFT, double excitations in finite systems. In order to achieve this, we use the Bethe-Salpeter equation with a dynamically screened Coulomb interaction W(omega), which can describe these excitations, and from this we obtain the xc kernel. Using a two-electron model system, we show that the frequency dependence of W does indeed introduce the double excitations that are instead absent in any static approximation of the electron-hole screening.

A note on quantum field theories with a minimal length scale

The aim of this note is to address the low energy limit of quantum field theories with a minimal length scale. The essential feature of these models is that the mininal length acts as a regulator in the asymptotic high energy limit which is incorporated through an infinite series of higher order derivatives. If one investigates a perturbative expansion in inverse powers of the Planck mass, one generically obtains extra poles in the propagator, and instabilities connected with the higher order derivative Lagrangian, which are however artifacts of truncating the series.

Effect of the phase transition on the infrared spectra of improper ferroelastic Hg2Cl2

The effect of the improper ferroelastic transition on the IR spectra of the Hg2Cl2 crystal is considered. It is shown that, due to lattice anharmonicity, the distortions caused by the phase transition give rise to mixing of the normal modes of the higher symmetry phase of the crystal, which results in the appearance of extra poles in the frequency dependence of the lattice permittivity. Experimentally, such extra poles manifest themselves in the appearance of extra lines in the IR absorption spectra. Symmetry analysis shows that this effect in Hg2Cl2 is strongly anisotropic in the plane normal to the tetragonal axis of the crystal.

An Approach to Producing Controlled Radial Force in a Switched Reluctance Motor

Unbalanced radial force acting on a rotor shaft is undesirable because it causes motor vibrations. However, motor vibrations can be reduced with intentionally produced shaft radial force which cancels the existing unbalanced radial forces due to a nonuniform air gap or external load. Due to its special structure, the shaft radial force and torque of a switched reluctance motor (SRM) can be separately controlled when all pole currents are controlled independently. However, control of SRM radial force is rarely discussed in the existing literature. This paper presents a scheme that produces a controlled radial force for a 12/8-pole SRM. In this scheme, mutual inductances between stator poles are included in the control model. The motor torque is controlled with the conventional method, i.e., all poles in the conduction phase are energized with the same current to produce the desired torque. Two extra poles from the descending-inductance phase are energized to produce the desired radial force. The cross-coupling torque produced by the force producing poles is compensated. The experimental results have verified that when controlled with the proposed scheme, the SRM was able to produce a controlled radial force when at standstill or running, and subjected to a load torque.

AtMAP70-5, a divergent member of the MAP70 family of microtubule-associated proteins, is required for anisotropic cell growth inArabidopsis

AtMAP70-5 is the most divergent of a recently described multigene family of plant-specific microtubule-associated proteins (MAPs). It is significantly smaller than other members and has several isoform-specific sequence features. To confirm that this protein still functions as a MAP we show that it directly binds microtubules in vitro and decorates microtubules in vivo. When added to tubulin polymerization assays, AtMAP70-5 increases the length distribution profile of microtubules indicating that it stabilizes microtubule dynamics. The overexpressed fusion protein perturbs cell polarity in cell suspensions by inducing extra poles for growth. Similarly, in Arabidopsis plants the overexpression of AtMAP70-5 causes epidermal cells to swell; it also stunts growth and induces right-handed organ twisting. RNAi-mediated downregulation of AtMAP70-5 results in reduced inflorescence stem length and diameter and individual cells are inhibited in their capacity for expansion. These observations suggest that the control over AtMAP70-5 expression levels is important in order to maintain axial polarity and to ensure regular extension of plant organs.

A Rae1-Containing Ribonucleoprotein Complex Is Required for Mitotic Spindle Assembly

Centrosome-independent microtubule polymerization around chromosomes has been shown to require a local gradient of RanGTP, which discharges mitotic cargoes from the nuclear import receptor importin beta. Here, we have used an activity-based assay in Xenopus egg extracts to purify the mRNA export protein Rae1 as a spindle assembly factor regulated by this pathway. Rae1 is a microtubule-associated protein that binds directly to importin beta. Depletion of Rae1 from extracts or cells severely inhibits mitotic spindle assembly. A purified Rae1 complex stabilizes microtubules in egg extracts in a RanGTP/importin beta-regulated manner. Interestingly, Rae1 exists in a large ribonucleoprotein complex, which requires RNA for its activity to control microtubule dynamics in vitro. Furthermore, we provide evidence that RNA associates with the mitotic spindle and that it plays a direct, translation-independent role in spindle assembly. Our studies reveal an unexpected function for RNA in spindle morphogenesis.

CLASSIFICATION OF THE SCALAR MESONS: A STRANGE POLE EXPEDITION INTO CHARM AND BEAUTY TERRITORY

The classification of scalar and vector mesons is reviewed within the framework of the Resonance-Spectrum Expansion (RSE). This method allows a simple and straightforward description of non-exotic meson–meson scattering, incorporating the effects of quark confinement and OZI-allowed decay in a fully nonperturbative way. Results for resonances and bound states are compared to experiment, on the basis of computed pole positions and cross-sections. New predictions for open-charm and -bottom scalar mesons are presented.Concretely, observed vector states for [Formula: see text] and [Formula: see text] are reproduced, and others are predicted. In the light scalar sector, the now established two nonets, one below 1 GeV and one in the region 1.3–1.5 GeV, are easily described, through the appearance of extra poles in the S-matrix. The recently found [Formula: see text](2317) meson is accurately reproduced by the same mechanism, as a quasi-bound state in the coupled [Formula: see text] system.In S-wave Dπ and Bπ scattering, new resonances are foreseen close to threshold, i.e. a [Formula: see text] at 2.16±0.05 GeV some 250 MeV wide, and a [Formula: see text] at 5.47±0.05 GeV with a width of about 50 MeV. Additional predictions concern the existence of [Formula: see text] and [Formula: see text] scalar mesons, stable with respect to OZI-allowed decay to BK and BD, respectively, namely at 5.61±0.05 GeV resp. 6.64±0.05 GeV.

Borealin: a novel chromosomal passenger required for stability of the bipolar mitotic spindle.

The chromosomal passenger complex of Aurora B kinase, INCENP, and Survivin has essential regulatory roles at centromeres and the central spindle in mitosis. Here, we describe Borealin, a novel member of the complex. Approximately half of Aurora B in mitotic cells is complexed with INCENP, Borealin, and Survivin; and Borealin binds Survivin and INCENP in vitro. A second complex contains Aurora B and INCENP, but no Borealin or Survivin. Depletion of Borealin by RNA interference delays mitotic progression and results in kinetochore–spindle misattachments and an increase in bipolar spindles associated with ectopic asters. The extra poles, which apparently form after chromosomes achieve a bipolar orientation, severely disrupt the partitioning of chromosomes in anaphase. Borealin depletion has little effect on histone H3 serine10 phosphorylation. These results implicate the chromosomal passenger holocomplex in the maintenance of spindle integrity and suggest that histone H3 serine10 phosphorylation is performed by an Aurora B–INCENP subcomplex.

Thermal one- and two-graviton Green’s functions in the temporal gauge

The thermal one- and two-graviton Green's function are computed using a temporal gauge. In order to handle the extra poles which are present in the propagator, we employ an ambiguity-free technique in the imaginary-time formalism. For temperatures T high compared with the external momentum, we obtain the leading T^4 as well as the subleading T^2 and log(T) contributions to the graviton self-energy. The gauge fixing independence of the leading T^4 terms as well as the Ward identity relating the self-energy with the one-point function are explicitly verified. We also verify the 't Hooft identities for the subleading T^2 terms and show that the logarithmic part has the same structure as the residue of the ultraviolet pole of the zero temperature graviton self-energy. We explicitly compute the extra terms generated by the prescription poles and verify that they do not change the behavior of the leading and sub-leading contributions from the hard thermal loop region. We discuss the modification of the solutions of the dispersion relations in the graviton plasma induced by the subleading T^2 contributions.

Slowly varying tachyon and tachyon potential

We show that the scattering amplitude of four open string scalars or tachyons on the world-volume of a D$_p$-brane in the bosonic string theory can be written in a universal form. The difference between this amplitude and the corresponding amplitude in the superstring theory is in an extra tachyonic pole. We show that in an $\alpha'$ expansion and for slowly varying fields, the amplitude is consistent with the tachyonic DBI action in which the even part of the tachyon potential is $V(T)=e^{-(\sqrt{\pi} T/\alpha)^2}$ with $\alpha=1$ for bosonic theory and $\alpha=\sqrt{2}$ for superstring theory.

Non-commutativity and Ramond–Ramond fields

We study the properties of the Ramond fields in superstring theory in the presence of a constant B-field and the subsequent implications of spacetime non-commutativity for spacetime fermions and spacetime supersymmetry. We find that the non-commutativity of spacetime coordinates leads to extra singularities in the spin field correlators and to appearance of the extra poles in the RR scattering amplitudes, carrying the opposite GSO parities.

Analysis of non-ideal characteristics of an ac-basedcapacitance transducer for tomography

An ac-based capacitance transducer has been designed for use inelectrical capacitance tomography systems. It has a high signal-to-noise ratioand good stray-immunity, compared with a charge/discharge transducer designedfor the same purpose. However, the non-ideal characteristics of amplifiers andCMOS switches limit the performance of the ac-based transducer. This paperanalyses the effects of the frequency-dependent gain of the amplifiers and thefinite `on' resistance of the CMOS switches. It is shown that the non-idealcharacteristics restrict the frequency response of the transducer byintroducing extra poles, which depend not only on the parameters of thedevices but also on the stray capacitance. Mathematical expressionsquantifying these effects are presented.

"It takes two to tango": understanding how centrosome duplication is regulated throughout the cell cycle.

The essence of successful mitosis is the generation of two genetically identical daughter cells. This requires the assembly of a strictly bipolar mitotic apparatus that will ensure that all daughter chromosomes are segregated to opposite sides of the cell before the completion of mitosis. The agent of the higher animal cell for the establishment of this essential “twoness” is the pair of centrosomes that organize the spindle poles during mitosis (Mazia 1987). Before the cell enters mitosis, the single interphase centrosome duplicates or reproduces exactly once, and the daughter centrosomes form the two poles of the spindle after breakdown of the nuclear envelope. Failure of the cell to precisely control this duplication of the centrosome can have disastrous consequences. If the centrosome fails to duplicate before the onset of mitosis, most somatic cells eventually return to interphase without dividing, which causes polyploidy. If the centrosome duplicates more than once in a cell cycle, then a multipolar spindle may be assembled and the chromosomes may be unequally distributed to the daughter cells, leading to genetic imbalances that produce cells with aggressive growth characteristics (for reviews, see Orr-Weaver and Weinberg 1998; Brinkley 2001). In fact, the cells of many lethal human tumors are genetically unstable and have abnormally high numbers of centrosomes (Lingle et al. 1998; Pihan et al. 1998; Carroll et al. 1999). Extra centrosomes are a problem because the condition is not remediated; cells do not have a checkpoint that aborts mitosis in response to extra spindle poles (Sluder et al. 1997). In this review, we focus on the mechanisms that control centrosome duplication and coordinate it with nuclear events during the cell cycle.

Modeling, analysis, and design criteria of actively clamped double-ended converters

The characteristics of actively clamped double-ended (ACDE) converters are studied. It is found that they possess interesting features such as near-zero output current ripple and require no magnetic reset winding. A low-frequency behavior model of the ACDE converter is derived, from which important relationships among output voltage V/sub 0/, input voltage V/sub i/, and duty cycle D are obtained. When compared with other forward-derived converters, an ACDE converter has extra poles and zeros in the small-signal control-to-output and input-to-output transfer functions. The design criteria and experimental results are also reported.

Influence of Centriole Behavior on the First Spindle Formation in Zygotes of the Brown AlgaFucus distichus(Fucales, Phaeophyceae)

The influence of centrioles, derived from the sperm flagellar basal bodies, and the centrosomal material (MTOCs) on spindle formation in the brown algaFucus distichus(oogamous) was studied by immunofluorescence microscopy using anti-centrin and anti-β-tubulin antibodies. In contrast to a bipolar spindle, which is formed after normal fertilization, a multipolar spindle was formed in polyspermic zygote. The number of mitotic poles in polyspermic zygotes was double the number of sperm involved in fertilization. As an anti-centrin staining spot (centrioles) was located at these poles, the multipolar spindles in polyspermic zygotes were produced by the supplementary centrioles. When anucleate egg fragments were fertilized, chromosome condensation and mitosis did not occur in the sperm nucleus. Two anti-centrin staining spots could be detected, microtubules (MTs) radiated from nearby, but the mitotic spindle was never produced. When a single sperm fertilized multinucleate eggs (polygyny), abnormal spindles were also observed. In addition to two mitotic poles containing anti-centrin staining spots, extra mitotic poles without anti-centrin staining spots were also formed, and as a result multipolar spindles were formed. When karyogamy was blocked with colchicine, it became clear that the egg nucleus proceeded independently into mitosis accompanying chromosome condensation. A monoastral spindle could be frequently observed, and in rare cases a barrel-shaped spindle was formed. However, when a sperm nucleus was located near an egg nucleus, the two anti-centrin staining spots shifted to the egg nucleus from the sperm nucleus. In this case, a normal spindle was formed, the egg chromosomes arranged at the equator, and the associated MTs elongated from one pole of the egg spindle toward the sperm chromosomes which were scattered. From these results, it became clear that paternal centrioles derived from the sperm have a crucial role in spindle formation in the brown algae, such as they do during animal fertilization. However, paternal centrioles were not adequate for the functional centrosome during spindle formation. We speculated that centrosomal materials from the egg cytoplasm aggregate around the sperm centrioles and are needed for centrosomal activation.

Pole placement for linear time-varying non-lexicographically fixed MIMO systems

This document is the third in a series of recent eigenvalue placement studies by the authors. In the first two publications (Valasek and Olgac, 1995a, Automatica, 31(11) 1605–1617 and 1995b IEE Control Theory Appl. Proc 142 (5), 451–458) the extension of Ackermann’s formula to time varying SISO and later to time-invariant and -varying MIMO systems were presented. Pole placement for linear time-varying systems means that the closed-loop system is equivalent via a Lyapunov transformation to a linear time-invariant system with poles at prescribed locations. In addition to the controllability condition, a critical property in this process is lexicographically fixedness, which was taken as granted at all times in the prior work. In this paper we deal with the pole placement of linear time-varying MIMO systems which are not lexicographically fixed. This effort removes the last restriction in the pole placement of such systems aside from being controllable. The original linear time-varying MIMO system which is not lexicographically fixed is augmented by appending additional state equations to ensure that the embedded system has the property of lexicographically fixedness. The poles are then placed as desired for this augmented system using the techniques presented in our previous publications. There is an added work of placing also the extra poles which appear due to the augmentation. However, they can be selected sufficiently away from the originally intended poles so that they do not influence the system behavior. Examples are provided to validate this claim.

A simple method to guarantee closed-loop stability when continuous-time systems are discretized

Sophisticated techniques fail to guarantee closed loop stability of discretized continuous-time systems. The simple, foolproof approach of mapping eigenvalues under z=esT is explored here. The result has a partial fraction type solution, implementable by such common teaching aids as Program CC. An increase in controller order may be necessary, but guidance on extra pole locations is given based on elementary measures such as gain and phase margin.

2D-component fermion on a(1+D)-dimensional Euclidean lattice with discrete chiral symmetries

We formulate the Dirac equation by a proficient method on a (1+$D$)-dimensional Euclidean lattice and get some new results. First, the obtained dispersion relation of the lattice fermion has no extra poles. Second, the components of the fermion is ${2}^{D}$, which should be compared to the ${2}^{D+1}$ of the Kogut-Susskind (KS) fermion. Furthermore we can explicitly show that the theory has the KS discrete chiral symmetry. All the lattice fermions tend to the usual fermions on continuous spacetime.