Hall Type Research Articles

Higher Order Asymptotic Cumulants of Studentized Estimators in Covariance Structures

In covariance structure analysis, the Studentized pivotal statistic of a parameter estimator is often used since the statistic is asymptotically normally distributed with mean zero and unit variance. For more accurate asymptotic distribution, the first and third asymptotic cumulants can be used to have the single-term Edgeworth, Cornish-Fisher, and Hall type asymptotic expansions. In this paper, the higher order asymptotic variance and the fourth asymptotic cumulant of the statistic are obtained under nonnormality when the partial derivatives of a parameter estimator with respect to sample variances and covariances up to the third order and the moments of the associated observed variables up to the eighth order are available. The result can be used to have the two-term Edgeworth expansion. Simulations are performed to see the accuracy of the asymptotic results in finite samples.

Acoustic investigations of concert halls for rock music

Objective measurement data and subjective evaluations have been collected from 20 small-/medium-sized halls in Denmark used for amplified rhythmic music concerts (pop, rock, jazz). The purpose of the study was to obtain knowledge about optimum acoustic conditions for this type of hall. The study is motivated by the fact that most concert tickets sold in Denmark relate to concerts within these genres in this kind of venue. The subjective evaluations were carried out by professional musicians and sound engineers who responded on the basis of their experiences working in these (and other) halls. From the relationships between the subjective evaluations and the objective data, recommended values for reverberation time across frequency are suggested. For halls with volume between 50.000 ft3 and 160.000 ft3, the optimal range is 0.7 s to 1.0 s without audience (and chairs). T30 should be frequency independent, so that clarity remains high also at the lower frequencies. A lower limit for T30 was identified. The paper also proposes possible hall designs that seek to fulfill the demands of sound engineers and musicians, as found in the investigation.

Oriented star packings

Given a (possibly infinite) family S of oriented stars, an S -packing in a digraph D is a collection of vertex disjoint subgraphs of D, each isomorphic to a member of S . The S - Packing problem asks for the maximum number of vertices, of a host digraph D, that can be covered by an S -packing of D. We prove a dichotomy for the decision version of the S -packing problem, giving an exact classification of which problems are polynomial time solvable and which are NP-complete. For the polynomial problems, we provide Hall type min-max theorems, including versions for (locally) degree-constrained variants of the problems. An oriented star can be specified by a pair of ( k , ℓ ) ∈ N 2 ∖ ( 0 , 0 ) denoting the number of out- and in-neighbours of the centre vertex. For p , q , d ∈ N ∪ { ∞ } , we denote by S p , q , d the family of stars ( k , ℓ ) such that k ⩽ p , and ℓ ⩽ q , and 0 < k + ℓ ⩽ d . We prove the S - Packing problem is polynomial if S = S p , q , d for some p , q , d ∈ Z + ∪ { ∞ } , and NP-complete otherwise.

Persistent upper airway obstruction is a diagnostic feature of spondyloepimetaphyseal dysplasia with multiple dislocations (Hall type) with further evidence for dominant inheritance

The spondyloepimetaphyseal dysplasias (SEMD) are a group of skeletal dysplasias of variable severity with a heterogeneous genetic aetiology. SEMD with multiple dislocations (Hall type) is a recently identified disorder (OMIM 603546) which is characterized by striking epiphyseal and metaphyseal changes of the long bones and joint laxity with multiple dislocations of the large joints. We report on persistent inspiratory stridor in a child with this type of SEMD in the second reported family with dominant transmission of this disorder. Microlaryngoscopy showed laryngeal stenosis due to failure of abduction of the vocal cords and a tracheostomy was required to provide a satisfactory airway. Since airway compromise has been reported previously in a small series of patients (total of five out of 13 cases so far), the evidence to date supports the association of upper airway obstruction in early childhood with the Hall type of SEMD. We therefore suggest that this is a clinically important diagnostic feature of this disorder.

Non-Tangential Limits of Bloch Functions

We give a sufficient condition for a function f in the “little Bloch space” \({\cal B}_0\) to have a finite non-tangential limit at a point ξ with ¦ξ¦ = 1. Our result can be viewed as an “one-sided” theorem of Hall type for the space \({\cal B}_0\).

A new temporal method for the identification of source directions in a reverberant hall

The study presented here is related to the reduction of noise in factory halls. The type of factory hall considered here has large dimensions and contain several industrial machines, running 24 h a day. A method is presented to determine the angular directions which provide the main contributions to the sound levels at any point in the hall. These directions correspond to the sources and their images on the walls and on the obstacles. The method is based on the use of cross-correlation functions of sound signals measured on a microphone array. It is adapted to the constraints of the problem (short measurement time, no possibility to stop the machines, small dimensions of the array, etc.). Experimental results are shown first for several test cases carried out in a semi-anechoic room and in a rectangular room, and, then, for the case of a surface-planing machine in a cluttered hall.

A novel “magnetic” field and its dual non-commutative phase space

In this Letter we have studied a new form of non-commutative (NC) phase space with an operatorial form of noncommutativity. A point particle in this space feels the effect of an interaction with an “ internal ” magnetic field, that is singular at a specific position θ −1 . By “internal” we mean that the effective magnetic fields depends essentially on the particle properties and modifies the symplectic structure. Here θ is the NC parameter and induces the coupling between the particle and the “internal” magnetic field. The magnetic moment of the particle is computed. Interaction with an external physical magnetic field reveals interesting features induced by the inherent fuzziness of the NC phase space: introduction of non-trivial structures into the charge and mass of the particle and possibility of the particle dynamics collapsing to a Hall type of motion. The dynamics is studied both from Lagrangian and symplectic (Hamiltonian) points of view. The canonical (Darboux) variables are also identified. We briefly comment, that the model presented here, can play interesting role in the context of (recently observed) real space Berry curvature in material systems.

Short cycle structures for graphs on surfaces and an open problem of Mohar and Thomassen

In this paper we investigate cycle base structures of a (weighted) graph and show that much information of short cycles is contained in an MCB (i.e., minimum cycle base). After setting up a Hall type theorem for base-transformation, we give a sufficient and necessary condition for a cycle base to be an MCB. Furthermore, we show that the structure of MCB in a (weighted) graph is unique. The property is also true for those having a longest length (although much work has been down in evaluating MCB, little is known for those having a longest length). We use those methods to find out some unknown properties for short cycles sharing particular properties in (unweighted) graphs. As applications, we determine the structures of short cycles in an embedded graph and show that there exist polynomially bounded algorithms in finding a shortest contractible cycle and a shortest two-sided cycle provided such cycles exist. Those answer an open problem of B. Mohar and C. Thomassen.

Fractional Quantum Hall States of Atoms in Optical Lattices

We describe a method to create fractional quantum Hall states of atoms confined in optical lattices. We show that the dynamics of the atoms in the lattice is analogous to the motion of a charged particle in a magnetic field if an oscillating quadrupole potential is applied together with a periodic modulation of the tunneling between lattice sites. In a suitable parameter regime the ground state in the lattice is of the fractional quantum Hall type, and we show how these states can be reached by melting a Mott-insulator state in a superlattice potential. Finally, we discuss techniques to observe these strongly correlated states.

A new familial case of spondylo-epi-metaphyseal dysplasia with multiple dislocations Hall type (leptodactylic form)

We report a father and son affected by spondylo-epi-metaphyseal dysplasia with multiple dislocations (Hall type), also called leptodactylic form. This family contributes to the delineation of the clinical and radiological phenotype of this rare condition.

MARKUP, RETURNS TO SCALE, THE BUSINESS CYCLE AND OPENNESS: EVIDENCE FROM AUSTRALIAN MANUFACTURING

This paper aims to measure markup and returns to scale for eight Australian manufacturing industries, for the period 1971‐72 to 1984‐85, and to explore the relationship between markup, the business cycle and openness to the international economy in this period. A Hall type model is used for this purpose, where allowance is made for non‐stochastic time variation in the contribution of technical change to output growth and intermediate materials are included in the production function.

Boat anchoring on Posidonia oceanica beds in a marine protected area (Italy, western Mediterranean): effect of anchor types in different anchoring stages

Seagrasses worldwide are noted for suffering from mechanical damage caused by boat anchoring. This is particularly so in sites highly frequented by boaters (marine protected areas or coastal urbanised areas). In the last decades, different strategies have been put into practice to reduce such impacts on seagrasses (i.e. by anchoring bans or by deploying boat moorings). More recently, in consideration that few marine protected area (MPA) management bodies or local administrations have the resources to enforce their anchorage regulations, the self-regulatory approach based on education and information of boaters has been preferred in several cases. At present, however, very little is known on the correct anchoring practices to ensure the safeguarding of seagrasses. The aim of the present study was to experimentally quantify in the field the damage caused to Posidonia oceanica shoot density by anchoring. A multifactorial experiment was designed to test whether the damage is dependent on (1) different anchor types (Hall, Danforth and Folding grapnel), (2) the use of a chain vs. a rope, (3) the three anchoring stages (anchor fall, dragging/lock-in and weighing), and finally (4) whether the pattern is consistent among different locations of the meadow. As expected, the three anchor types employed in the present study differed in the levels of damage inflicted on the P. oceanica meadows of the Ustica Island MPA. In particular, the use of the Hall type anchor seems to be preferable to minimise this impact in comparison with the other two anchor types. Moreover, the effect on the meadow of the three anchor types is greatly dependent on the anchoring stage. These results confirm that the weighing stage is the critical stage of the anchoring process. The number of damaged shoots of P. oceanica was not affected by the presence of the chain. These patterns were consistent between locations. In the long term, even anchoring on P. oceanica by small boats using low-impact anchors may potentially have detrimental consequences. For this reason, we suggest that in vulnerable sites, it is preferable to implement an educational program based on information of boaters on correct anchoring practices and anchor typology to use, rather than adopting strong restrictions to boat anchoring or deploying mooring buoys. Although the use of these management strategies is still recommended in the case of anchorage frequented by bigger vessels using heavier anchors and chains.

Influence of the plasma on ICRF antenna voltage limits

An ion cyclotron range of frequencies (ICRF) probe [F.W. Baity, G.C. Barber, V. Bobkov, R.H. Goulding, J.-M. Noterdaeme, D.W. Swain, in: 14th Topical Conference on Radiofrequency Power in Plasmas, Oxnard 2001, AIP Conference Proceedings 595, AIP, Melville, NY, 2001, p. 510] has been implemented to study voltage stand-off of the ICRF antennas on ASDEX Upgrade (AUG). The probe was operated at first in a test stand where features of high RF voltage operation in vacuum and plasma created by an ion source of the Hall type [Plasma Sources Sci. Technol. 8 (1999) R1] were studied. Vacuum arcs as well as ignition of high voltage glow discharge are candidate processes to explain voltage limits of the ICRF antennas. The setup on AUG was used to expose high RF voltages in real conditions of the tokamak scrape-off layer which are faced by the ICRF antennas. It is found that high voltage breakdown on the ICRF antenna is often correlated with ELM activity. The maximal RF voltage increased from shot to shot, i.e. the conditioning effect is observed. For the good-conditioned ICRF probe it was shown experimentally that the voltage limit can be increased while the rectified current is suppressed at the same time.

An Ion-Beam Apparatus for the Formation of Oxide Films by the Oxygen Ion Sputtering Technique

A source of oxygen ions operating on the basis of a two-stage self-sustained discharge with a cold hollow cathode is used in an apparatus for target sputtering. An assisting ion flow is produced by a Kaufmann open-end ion source of the Hall type. The sources are mounted in a vacuum volume and are operated simultaneously. Tantalum oxide, silicon oxide, and barium titanate films obtained by using an assisting ion flow are more homogeneous and have a narrower film–substrate transition layer and a composition closer to the stoichiometric one than films obtained under identical conditions but without an ion-flow assistance.

Correlated random band matrices: localization-delocalization transitions

We study the statistics of eigenvectors in correlated random band matrix models. These models are characterized by two parameters, the bandwidth B(N) of a Hermitian NxN matrix and the correlation parameter C(N) describing correlations of matrix elements along diagonal lines. The correlated band matrices show a much richer phenomenology than models without correlation as soon as the correlation parameter scales sufficiently fast with matrix size. In particular, for B(N) approximately sqrt[N] and C(N) approximately sqrt[N], the model shows a localization-delocalization transition of the quantum Hall type.

Method to simulate the acoustical quality of a room and associated audio-digital processor

A method for the simulation of the acoustical quality produced by a virtual sound source and for the localizing of this source with respect to one or more listeners, and one or more original sound sources. This method consists in: 1) fixing values of perceptual parameters defining the acoustical quality to be simulated and values of parameters defining the localization of a virtual source, 2) converting these values into a pulse response described by its energy distribution as a function of the time and the frequency, 3) carrying out a context compensation so as to take account of an existing room effect, 4) obtaining an artificial reverberation from elementary signals so as to achieve a virtual acoustic environment in real time and control the localizing of the virtual source. This method can be used to modify sound signals coming from a real source, or to create sound effects on recording media. An acoustic virtual processor which enables implementation of this method comprises a signal processing "room" module that enables the obtaining of an artificial reverberation and a signal processing "pan" module enabling the controlling of the localization and the movement of the sound source and that carries out a format conversion into another reproduction mode. The acoustic virtual processor can be used to fit out all types of entertainment halls or games halls.

Characterization of varietal covering and stem groups

Let A m be the variety of abelian groups of exponent m, where mis a square free positive integer. It is shown that every group G has an A m -covering group, which generalizes the work of I. Schur (1904) and M.R. Jones (1973). Also, similar to the work of Yamazaki (1964) in the variety of abelian groups, if 1→ A → H → G → 1 is an A m -stem extension, then we show that H is a homomorphic image of an A m -covering group of G. Finally,in this variety some results of Hall's type will be proved.

Business Dynamics and Efficiency in Industries and Regions: The Case of Spain

High rates of firm births and deaths are a pervasive phenomenon across industries and territories. Most studies have related the great turbulence at the fringe of practically all manufacturing industries to positive effects on the long-run performance of industries. According to these views business turbulence, although it has a relatively small incidence on net entry, leads to allocative improvement and stimulates innovation. The existing set of empirical studies does not reach clear conclusions, however, and many questions are still open. Our contribution analyses the relationship between business dynamics in manufacturing and the growth of total factor productivity in industries and regions. After a review of current literature on entry and exit it is argued that most models are tailored to suit the processes observed in industries and regions that are near the technological frontier, and we propose an approach that could be more representative of middle range economies such as Spain. According to this approach new firms are seen more as users of innovations than producers of innovations. We adopt a model based on a vintage capital framework in which new entrants embody the edge technologies available and exiting businesses are supposed to represent the most marginal obsolete plants. Both industries and regions are represented by a Hall's type production function which controls for imperfect competition and economies of scale. The results show that both entry and exit rates contribute positively to the growth of total factor productivity in industries and in regions.

The Newest Inductee in the Number Hall of Fame

Rational and irrational, algebraic and transcendental, whole, natural, positive, negative, even, odd, prime, cardinal, ordinal, yes even p-adic numbers: It gives me great pleasure to welcome you all to these induction ceremonies at the Number Hall of Fame here in Canton, Ohio. It's truly gratifying to see such a tremendous and diverse turnout for this event. How wonderful it is that we can forget our differences, put aside our animosities, and come together to honor those amongst us who have truly achieved a purpose in life above and beyond our appearance on ledgers, computer screens, and cash registers around the globe. The vast throng of numbers here today must reflect, at least in part, the rarity of these occasions. We are not that type of Hall of Fame where any number eventually makes the cut. Not like the Hall of Fame of Physical Constants, where a number is embarrassed not to eventually appear in their list. No, as you can see by the small set of numbers sitting up on the dais, including most of the past recipients of the award, this honor is bequeathed on only a select few. Let me quickly introduce you to our past recipients. On the far left we have the first inductee into the Number Hall of Fame, someone I need say little about, as eveiyone knows her well. Yes, it's the delightful number One. How could anyone be less than charmed by her ability to multiply a number without altering it? Sitting to the left of One is the incomparable e, that paradoxical sorcerer who when put to the power x becomes his own derivative. What a pleasure it is to have you here today, sir. Just to the left of e, we have that mandarin enigma, the Buddha of math, Mr. Zero. Please, don't get up. It's not a good idea after your triple bypass. Next to Mr. Zero, we have the ebullient Two. As he is all too fond of saying, You need Two to tango. Seated next to Two is his son, V2, who with his simple and forthright manner, hardly deserves to be called irrational. Seated in the empty chair to the left of V? is his imaginary friend i. Please, no snickering from you Bernoulli numbers in the back. Having an imaginary friend doesn't necessarily mean you're a couple million digits past rational, even if in this particular case, it happens to be true. I1+ V/U And at the end sits 2 , that icon of Greek aesthetics, known affectionately as the Golden Ratio. Her attendance at any event brings an elegance and refinement to the proceedings. Several of our inductees could not be with us today, including Euler's constant, N

Analysis of carrier concentration, lifetime, and electron mobility on p-type HgCdTe

Minority carrier transport characteristics of vacancy-doped p-type HgCdTe such as carrier concentration, lifetime, and mobility are investigated. In the calculation of the carrier concentration two acceptor levels—a donor level and a trap level—were taken into account. The acceptor levels have been described by two models—two independent singly ionized levels and a divalent level with two ionization energies. When each model was examined by calculating electron mobility as a function of temperature, the latter was found to be more accurate. Electron mobility as a function of majority carrier concentration was also presented for both n-type and p-type HgCdTe with 0.225 Cd mole fraction. Steady state electron lifetime was computed assuming the acceptor levels and the trap level would act as Schokley–Read–Hall type recombination centers. The calculated results using the divalent acceptor model were in good agreement with the experimental data.