bluuebunny/crossref_metadata_2025 huggingface dataset:
On the unitary dual of 𝑆𝑝𝑖𝑛(2𝑛,ℂ)
Authors: Brega Alfredo
Published: July 2002

In this paper we begin a systematic study of the unitarity question for genuine representations of the group

S
p
i
n
(
2
n
,

C

)

Spin (2 n, \mathbb {C})

. The main result is that we find a class of unitary representations (mostly isolated) analogous to the special unipotent representations defined by D. Barbasch and D. Vogan. In particular the full unitary dual of

S
p
i
n
(
2
n
,

C

)

Spin (2 n, \mathbb {C})

should be obtainable from this set by complementary series.
Geometry of Cantor Systems
Authors: Jiang Yunping
Published: July 2002

A Cantor system is defined. The geometry of a certain family of Cantor systems is studied. Such a family arises in dynamical systems as hyperbolicity is created. We prove that the bridge geometry of a Cantor system in such a family is uniformly bounded and that the gap geometry is regulated by the size of the leading gap.
Criteria of algebraic independence with multiplicities and interpolation determinants
Authors: Laurent Michel , Roy Damien
Published: July 2002

We generalize Gel’fond’s criterion of algebraic independence by taking into account the values of the derivatives of the polynomials, and show how the new criterion applies to proving results of algebraic independence using interpolation determinants. We also establish a new result of approximation of a transcendental number by algebraic numbers of bounded degree and size. It contains an earlier result of E. Wirsing and also a result announced by A. Durand.
On the degree of groups of polynomial subgroup growth
Authors: Shalev Aner
Published: July 2002

LetGGbe a finitely generated residually finite group and letan(G)a_n(G)denote the number of indexnnsubgroups ofGG. Ifan(G)≤nαa_n(G) \le n^{\alpha }for someα\alphaand for allnn, thenGGis said to have polynomial subgroup growth (PSG, for short). The degree ofGGis then defined bydeg⁡(G)=lim suplog⁡an(G)log⁡n\operatorname {deg}(G) = \limsup {{\log a_n(G)} \over {\log n}}. Very little seems to be known about the relation betweendeg⁡(G)\operatorname {deg}(G)and the algebraic structure ofGG. We derive a formula for computing the degree of certain metabelian groups, which serves as a main tool in this paper. Addressing a problem posed by Lubotzky, we also show that ifH≤GH \le Gis a finite index subgroup, thendeg⁡(G)≤deg⁡(H)+1\operatorname {deg}(G) \le \operatorname {deg}(H)+1. A large part of the paper is devoted to the structure of groups of small degree. We show thatan(G)a_n(G)is bounded above by a linear function ofnnif and only ifGGis virtually cyclic. We then determine all groups of degree less than3/23/2, and reveal some connections with plane crystallographic groups. It follows from our results that the degree of a finitely generated group cannot lie in the open interval(1,3/2)(1, 3/2). Our methods are largely number-theoretic, and density theorems à la Chebotarev play essential role in the proofs. Most of the results also rely implicitly on the Classification of Finite Simple Groups.
Universal constraints on the range of eigenmaps and spherical minimal immersions
Authors: Toth Gabor
Published: July 2002

The purpose of this paper is to give lower estimates on the range dimension of spherical minimal immersions in various settings. The estimates are obtained by showing that infinitesimal isometric deformations (with respect to a compact Lie group acting transitively on the domain) of spherical minimal immersions give rise to a contraction on the moduli space of the immersions and a suitable power of the contraction brings all boundary points into the interior of the moduli space.
The set of idempotents in the weakly almost periodic compactification of the integers is not closed
Authors: Bordbar B. , Pym J.
Published: July 2002

This paper answers negatively the question of whether the sets of idempotents in the weakly almost periodic compactifications of

(

N

,
+
)

(\mathbb {N}, +)

and

(

Z

,
+
)

(\mathbb {Z} ,+)

are closed.
Remarks on a Nonlinear Parabolic Equation
Authors: Ben-Artzi Matania , Goodman Jonathan , Levy Arnon
Published: July 2002

The equation

u

t

=
Δ
u
+
μ

|

∇
u

|

u_{t} =\Delta u +\mu |\nabla u |

,

μ
∈

R

\mu \in \mathbb {R}

, is studied in

R

n

\mathbb {R}^{n}

and in the periodic case. It is shown that the equation is well-posed in

L

1

L^{1}

and possesses regularizing properties. For nonnegative initial data and

μ
>
0

\mu >0

the solution decays in

L

1

(

R

n

)

L^{1}(\mathbb {R}^{n})

as

t
→
∞

t\to \infty

. In the periodic case it tends uniformly to a limit. A consistent difference scheme is presented and proved to be stable and convergent.
Transition operators of diffusions reduce zero-crossing
Authors: Evans Steven , Williams Ruth
Published: July 2002

If

u
(
t
,
x
)

u(t,x)

is a solution of a one–dimensional, parabolic, second–order, linear partial differential equation (PDE), then it is known that, under suitable conditions, the number of zero–crossings of the function

u
(
t
,
⋅
)

u(t,\cdot )

decreases (that is, does not increase) as time

t
t

increases. Such theorems have applications to the study of blow–up of solutions of semilinear PDE, time dependent Sturm Liouville theory, curve shrinking problems and control theory. We generalise the PDE results by showing that the transition operator of a (possibly time–inhomogenous) one–dimensional diffusion reduces the number of zero–crossings of a function or even, suitably interpreted, a signed measure. Our proof is completely probabilistic and depends in a transparent manner on little more than the sample–path continuity of diffusion processes.
Invariant measures for algebraic actions, Zariski dense subgroups and Kazhdan’s property (T)
Authors: Shalom Yehuda
Published: July 2002

Let

k
k

be any locally compact non-discrete field. We show that finite invariant measures for

k
k

-algebraic actions are obtained only via actions of compact groups. This extends both Borel’s density and fixed point theorems over local fields (for semisimple/solvable groups, resp.). We then prove that for

k
k

-algebraic actions, finitely additive finite invariant measures are obtained only via actions of amenable groups. This gives a new criterion for Zariski density of subgroups and is shown to have representation theoretic applications. The main one is to Kazhdan’s property

(
T
)

(T)

for algebraic groups, which we investigate and strengthen.
On the module structure of free Lie algebras
Authors: Bryant R. , Stöhr Ralph
Published: July 2002

We study the free Lie algebraLLover a field of non-zero characteristicppas a module for the cyclic group of orderppacting onLLby cyclically permuting the elements of a free generating set. Our main result is a complete decomposition ofLLas a direct sum of indecomposable modules.
Thermal capacity estimates on the Allen-Cahn equation
Authors: Sowers Richard , Wu Jang-Mei
Published: July 2002

We consider the Allen-Cahn equation in a well-known scaling regime which gives motion by mean curvature. A well-known transformation of this PDE, using its standing wave, yields a PDE the solution of which is approximately the distance function to an interface moving by mean curvature. We give bounds on this last fact in terms of thermal capacity. Our techniques hinge upon the analysis of a certain semimartingale associated with a certain PDE (the PDE for the approximate distance function) and an analogue of some results by Bañuelos and Øksendal relating lifetimes of diffusions to exterior capacities.
Diffeomorphisms approximated by Anosov on the 2-torus and their SBR measures
Authors: Sumi Naoya
Published: July 2002

We consider the

C

2

C^{2}

set of

C

2

C^{2}

diffeomorphisms of the 2-torus

T

2

\mathbb {T}^{2}

, provided the conditions that the tangent bundle splits into the directed sum

T

T

2

=

E

s

⊕

E

u

T\mathbb {T}^{2}=E^{s}\oplus E^{u}

of

D
f

Df

-invariant subbundles

E

s

E^{s}

,

E

u

E^{u}

and there is

0
>
λ
>
1

0>\lambda >1

such that

‖
D
f

|

E

s

‖
>
λ

\Vert Df|_{E^{s}}\Vert >\lambda

and

‖
D
f

|

E

u

‖
≥
1

\Vert Df|_{E^{u}}\Vert \ge 1

. Then we prove that the set is the union of Anosov diffeomorphisms and diffeomorphisms approximated by Anosov, and moreover every diffeomorphism approximated by Anosov in the

C

2

C^{2}

set has no SBR measures. This is related to a result of Hu-Young.
Random intersections of thick Cantor sets
Authors: Kraft Roger
Published: July 2002

Let

C

1

C_{1}

,

C

2

C_{2}

be Cantor sets embedded in the real line, and let

τ

1

\tau _{1}

,

τ

2

\tau _{2}

be their respective thicknesses. If

τ

1

τ

2

>
1

\tau _{1}\tau _{2}>1

, then it is well known that the difference set

C

1

−

C

2

C_{1}-C_{2}

is a disjoint union of closed intervals. B. Williams showed that for some

t
∈
int
⁡
(

C

1

−

C

2

)

t\in \operatorname {int} (C_{1}-C_{2})

, it may be that

C

1

∩
(

C

2

+
t
)

C_{1}\cap (C_{2}+t)

is as small as a single point. However, the author previously showed that generically, the other extreme is true;

C

1

∩
(

C

2

+
t
)

C_{1}\cap (C_{2}+t)

contains a Cantor set for all

t
t

in a generic subset of

C

1

−

C

2

C_{1}-C_{2}

. This paper shows that small intersections of thick Cantor sets are also rare in the sense of Lebesgue measure; if

τ

1

τ

2

>
1

\tau _{1}\tau _{2}>1

, then

C

1

∩
(

C

2

+
t
)

C_{1}\cap (C_{2}+t)

contains a Cantor set for almost all

t
t

in

C

1

−

C

2

C_{1}-C_{2}

.
Symplectic group lattices
Authors: Scharlau Rudolf , Tiep Pham
Published: July 2002

Let

p
p

be an odd prime. It is known that the symplectic group

S

p

2
n

(
p
)

Sp_{2n}(p)

has two (algebraically conjugate) irreducible representations of degree

(

p

n

+
1
)

/

2

(p^{n}+1)/2

realized over

Q

(

ϵ
p

)

\mathbb {Q}(\sqrt {\epsilon p})

, where

ϵ
=
(
−
1

)

(
p
−
1
)

/

2

\epsilon = (-1)^{(p-1)/2}

. We study the integral lattices related to these representations for the case

p

n

≡
1
mod
4

p^{n} \equiv 1 \bmod 4

. (The case

p

n

≡
3
mod
4

p^{n} \equiv 3 \bmod 4

has been considered in a previous paper.) We show that the class of invariant lattices contains either unimodular or

p
p

-modular lattices. These lattices are explicitly constructed and classified. Gram matrices of the lattices are given, using a discrete analogue of Maslov index.
On the distribution of inversive congruential pseudorandom numbers in parts of the period
Authors: Niederreiter Harald , Shparlinski Igor
Published: July 2002

The inversive congruential method is an attractive alternative to the classical linear congruential method for pseudorandom number generation. In this paper we present the first nontrivial bounds on the discrepancy of individual sequences of inversive congruential pseudorandom numbers in parts of the period. The proof is based on a new bound for certain incomplete exponential sums.
Harmonic functions of maximal growth: invertibility and cyclicity in Bergman spaces
Authors: Borichev Alexander , kan Hedenmalm Hå
Published: July 2002

In the theory of commutative Banach algebras with unit, an element generates a dense ideal if and only if it is invertible, in which case its Gelfand transform has no zeros, and the ideal it generates is the whole algebra. With varying degrees of success, efforts have been made to extend the validity of this result beyond the context of Banach algebras. For instance, for the Hardy space

H

2

H^{2}

on the unit disk, it is known that all invertible elements are cyclic (an element is cyclic if its polynomial multiples are dense), but cyclic elements need not be invertible. In this paper, we supply examples of functions in the Bergman and uniform Bergman spaces on the unit disk which are invertible, but not cyclic. This answers in the negative questions raised by Shapiro, Nikolskiĭ, Shields, Korenblum, Brown, and Frankfurt.
A Pieri-Chevalley formula in the K-theory of a 𝐺/𝐵-bundle
Authors: Pittie Harsh , Ram Arun
Published: July 2002

Let

G
G

be a semisimple complex Lie group,

B
B

a Borel subgroup, and

T
⊆
B

T\subseteq B

a maximal torus of

G
G

. The projective variety

G

/

B

G/B

is a generalization of the classical flag variety. The structure sheaves of the Schubert subvarieties form a basis of the K-theory

K
(
G

/

B
)

K(G/B)

and every character of

T
T

gives rise to a line bundle on

G

/

B

G/B

. This note gives a formula for the product of a dominant line bundle and a Schubert class in

K
(
G

/

B
)

K(G/B)

. This result generalizes a formula of Chevalley which computes an analogous product in cohomology. The new formula applies to the relative case, the K-theory of a

G

/

B

G/B

-bundle over a smooth base

X
X

, and is presented in this generality. In this setting the new formula is a generalization of recent

G
=
G

L
n

(

C

)

G=GL_n({\mathbb C})

results of Fulton and Lascoux.
Petrogenesis and Implications of Calc-Alkaline Cryptic Hybrid Magmas from Washburn Volcano, Absaroka Volcanic Province, USA
Authors: FEELEY T. C. , COSCA M. A. , LINDSAY C. R.
Published: July 2002

The petrogenesis of calc-alkaline magmatism in the Eocene Absaroka Volcanic Province (AVP) is investigated at Washburn volcano, a major eruptive center in the low-K western belt of the AVP. New 40Ar/39Ar age determinations indicate that magmatism at the volcano commenced as early as 55 Ma and continued until at least 52 Ma. Although mineral and whole-rock compositional data reflect near equilibrium crystallization of modal phenocrysts, petrogenetic modeling demonstrates that intermediate composition magmas are hybrids formed by mixing variably fractionated and contaminated mantle-derived melts and heterogeneous silicic crustal melts. Nd and Sr isotopic compositions along with trace element data indicate that silicic melts in the Washburn system are derived from deep-crustal rocks broadly similar in composition to granulite-facies xenoliths in the Wyoming Province. Our preferred explanation for these features is that mantle-derived basaltic magma intruded repeatedly in the deep continental crust leading to fractional crystallization, silicic melt production, and homogenization of magmas, followed by ascent to shallow reservoirs and crystallization of new plagioclase-rich mineral assemblages in equilibrium with the intermediate hybrid liquids. The implications of this process are that (1) some calc-alkaline magmas may only be recognized as hybrids on purely chemical grounds, particularly in systems where mixing precedes and is widely separated from crystallization in space and time, and (2) given the role ascribed to crustal processes at Washburn volcano, the variation between rocks that follow calc-alkaline trends in the western AVP and those that follow shoshonitic trends in the east cannot simply reflect higher pressures of fractionation to the east in Moho-level magma chambers in the absence of crustal interaction.
The mitotic spindle is required for loading of the DASH complex onto the kinetochore
Authors: Li Yumei , Bachant Jeff , Alcasabas Annette A. , Wang Yanchang , Qin Jun , Elledge Stephen J.
Published: July 2002

A role for the mitotic spindle in the maturation of the kinetochore has not been defined previously. Here we describe the isolation of a novel and conserved essential gene, ASK1, fromSaccharomyces cerevisiae involved in this process. ask1mutants display either G2/M arrest or segregation of DNA masses without the separation of sister chromatids, resulting in massive nondisjunction and broken spindles. Ask1 localizes along mitotic spindles and to kinetochores, and cross-links to centromeric DNA. Microtubules are required for Ask1 binding to kinetochores, and are partially required to maintain its association. We found Ask1 is part of a multisubunit complex, DASH, that contains ∼10 components, including several proteins essential for mitosis including Dam1, Duo1, Spc34, Spc19, and Hsk1. The Ipl1 kinase controls the phosphorylation of Dam1 in the DASH complex and may regulate its function. We propose that DASH is a microtubule-binding complex that is transferred to the kinetochore prior to mitosis, thereby defining a new step in kinetochore maturation.
Signal processing in scanning thermoacoustic tomography in biological tissues
Authors: Xu Yuan , Wang Lihong V.
Published: July 2002

Microwave‐induced thermoacoustic tomography was explored to image biological tissues. Short microwave pulses irradiated tissues to generate acoustic waves by thermoelastic expansion. The microwave‐induced thermoacoustic waves were detected with a focused ultrasonic transducer to obtain two‐dimensional tomographic images of biological tissues. The dependence of the axial and the lateral resolutions on the spectra of the signals was studied. A reshaping filter was applied to the temporal piezoelectric signals from the transducer to increase the weight of the high‐frequency components, which improved the lateral resolution, and to broaden the spectrum of the signal, which enhanced the axial resolution. A numerical simulation validated our signal‐processing approach.
Photon scatter in portal images: Physical characteristics of pencil beam kernels generated using the EGS Monte Carlo code
Authors: McCurdy B. M. C. , Pistorius S.
Published: July 2002

Pencil beam kernels describing scattered photon fluence behind homogeneous water slabs at various air gap distances were generated using the EGS Monte Carlo code. Photon scatter fluence was scored in separate bins based on the particle's history: singly scattered, multiply scattered, and bremsstrahlung and positron annihilation photons. Simultaneously, the mean energy and mean angle with respect to the incident photon pencil beam were tallied. Kernels were generated for incident photon pencil beams exhibiting monoenergetic spectra of 2.0 and 10.0 MeV, and polyenergetic spectra representative of 6 and 24 MV beams. Reciprocity was used to generate scatter fractions on the central axis for various field sizes, phantom thicknesses, and air gaps. The scatter kernels were further characterized by full width at half‐maximum estimates. Modulation transfer functions were calculated, providing theoretical estimates of the limit of performance of portal imaging systems due to the intrinsic scattering of photon radiation through the patient.
Quantum electrical transport in samples of limited dimensions
Authors: Holcomb D. F.
Published: July 2002

The ability to make electrically conducting structures of ever smaller size by nanofabrication techniques (the playground of mesoscopic physics) has brought with it entry into a wonderful new range of unexpected quantum phenomena. Interpretation of these phenomena requires full recognition of the wave nature of electrons and requires keeping track of the phase coherence of the electron wave functions and/or the discreteness of electron energy levels in samples of interest. Happily, many of the phenomena can be observed through the use of very straightforward experimental probes—commonly the dc electrical conductivity or conductance, and the Hall effect. The phenomena are observed in samples with one or more dimensions comparable to either the electron wavelength (up to 40 nm for carriers at the Fermi energy in some semiconductors) or the inelastic scattering length of the carriers (as large as many microns in some systems at low temperatures). Ohm’s law is no longer a firm guide to current–voltage relationships, and the Drude–Sommerfeld picture of electrical conduction is superseded. Many of the interesting phenomena are seen in samples of either two-dimensional (i.e., a third dimension is of the order of or less than the electron wavelength) or one-dimensional nature (either a tight, short constriction in the conductor or a longer “quantum wire”). In certain one-dimensional structures, one may have ballistic transport between input and output connections, and the quantum character of the electron motion is fully displayed. Planck’s constant h appears in the characteristic quantum of electrical conductance, e2/h. In two dimensions, the addition of a large magnetic field produces the remarkably deep and still somewhat mysterious Quantum Hall Effect, characterized by the quantum of resistance, RK=h/e2=25812.8 Ω. Other examples of the observation of electron interference and diffraction phenomena within solid materials are briefly highlighted. This short tutorial treatment emphasizes observed phenomena rather than details of the theoretical structures used to interpret them.
Bubble clouds and their transport within the surf zone as measured with a distributed array of upward-looking sonars
Authors: Dahl Peter H.
Published: July 2002

A collaborative, multi-institute experiment called the Scripps Pier Experiment was conducted in the vicinity of the Scripps pier in La Jolla, California, in March 1997 to study the fate of bubbles in the surf zone and the effects of these bubbles on acoustic propagation. This paper discusses data gathered by the Applied Physics Laboratory, University of Washington, using a set of four upward-looking sonars (frequency 240 kHz), which simultaneously measured vertical profiles of acoustic volume scattering from bubbles at four locations. The transport of bubbles via rip currents emerged as an important, though episodic and localized, feature of the acoustic environment in the surf zone. Images of volumetric backscattering strength vs time and depth reveal the episodic events (of increased scattering level) lasting between 5 and 10 min caused by the passage of bubble clouds over the sonar. Time lags for the onset of increased scattering at the four locations are consistent with a seaward velocity of the bubble clouds of order 10 cm/s, and the length scales of these bubble clouds in the seaward direction are inferred to be in the range 50–100 m. The influence of the incoming surface wave field is also discussed.
Scattering of Lamb waves by a circular cylinder
Authors: Wang Xiao-Min , Ying C. F.
Published: July 2002

Following our previous attempt at the scattering from a cylinder in a slab to the incidence of a guided shear wave, we hereby discuss the scattering by an elastic cylinder embedded in an isotropic plate for a variety of bonding states to incidence of the fundamental Lamb wave modes S0 and A0 at the low-frequency regime. The plate is divided up into three regions by introducing two imaginary planes located symmetrically some distance from the cylinder and perpendicular to surfaces of the plate. The wave fields in various regions are expanded either into cylinder wave modes or into Lamb wave modes. A system of equations determining the coefficients of expansion is obtained according to the traction-free boundary conditions on the plate walls and the displacement and stress continuity conditions across the virtual planes. By taking an appropriate finite number of terms of the infinite expansion series and some selected points on the two properly chosen imaginary planes and the surfaces of the plate through convergence and precision tests, a matrix equation to numerically evaluate the expansion coefficients is found. Coefficients of the reflection and transmission versus the normalized radius of the cylinder in welded, slip, and cracked interfacial conditions are numerically computed. In the low-frequency range, the relative errors are found to be less than 1%. Contrast curves of the reflection coefficient for the cylinder of nearly all permissible size in perfect and imperfect interfacial bonding are shown and prominent differences are noted.
Acoustic effects of the ATOC signal (75 Hz, 195 dB) on dolphins and whales
Authors: Au Whitlow W. L. , Nachtigall Paul E. , Pawloski Jeffrey L.
Published: July 2002

The Acoustic Thermometry of Ocean Climate (ATOC) program of Scripps Institution of Oceanography and the Applied Physics Laboratory, University of Washington, will broadcast a low-frequency 75-Hz phase modulated acoustic signal over ocean basins in order to study ocean temperatures on a global scale and examine the effects of global warming. One of the major concerns is the possible effect of the ATOC signal on marine life, especially on dolphins and whales. In order to address this issue, the hearing sensitivity of a false killer whale (Pseudorca crassidens) and a Risso’s dolphin (Grampus griseus) to the ATOC sound was measured behaviorally. A staircase procedure with the signal levels being changed in 1-dB steps was used to measure the animals’ threshold to the actual ATOC coded signal. The results indicate that small odontocetes such as the Pseudorca and Grampus swimming directly above the ATOC source will not hear the signal unless they dive to a depth of approximately 400 m. A sound propagation analysis suggests that the sound-pressure level at ranges greater than 0.5 km will be less than 130 dB for depths down to about 500 m. Several species of baleen whales produce sounds much greater than 170–180 dB. With the ATOC source on the axis of the deep sound channel (greater than 800 m), the ATOC signal will probably have minimal physical and physiological effects on cetaceans.
Effects of three parameters on speaking fundamental frequency
Authors: Hollien Harry , Hollien Patricia A. , de Jong Gea
Published: July 2002

Speaking fundamental frequency levels and usage (SFF, F0) are of interest to many investigators who study human speech and voice. Substantial research in the area has been carried out; common foci include SFF as related to infant cry, age, gender, adolescent voice change, language, race, voice pathology, and so on. Yet there still are a number of relationships which are not well understood and three of them will be addressed in this project. They involve the long-held notions that (1) a secular trend exists with SFF being lowered over time, (2) the use of university students in research of this type will create bias because they are physically different from average individuals, and (3) SFF can vary systematically for different types of speech (especially for oral reading and extemporaneous speaking). Experiments assessing these questions were carried out, but only certain of the postulates were supported. That is, while some evidence of a secular trend was found, it appeared inconsequential during the past quarter of this century; second, although university students were found to be slightly larger than a cohort approaching the average population, only minor vocal differences were found. Finally, it was observed that, in general, oral reading resulted in higher mean SFF’s than those for spontaneous speech. However, this difference was not robust and, due to reversals, the resulting metric did not appear to be of good predictive value for individual speakers.
The effect of compression ratio and release time on the categorical rating of sound quality
Authors: Neuman Arlene C. , Bakke Matthew H. , Mackersie Carol , Hellman Sharon , Levitt Harry
Published: July 2002

Two experiments were carried out to determine how manipulating the compression ratio and release time of a single-band wide dynamic range hearing aid affects sound quality. In experiment I, compression ratio was varied over the range from linear to 10:1 (low compression threshold, attack time=5 ms, release time=200 ms). In experiment II, compression ratios of 1.5, 2, and 3:1 were combined with release times of 60, 200, and 1000 ms (attack time=5 ms). Twenty listeners with sensorineural hearing loss rated the clarity, pleasantness, background noise, loudness, and the overall impression of speech-in-noise (Ventilation, Apartment, Cafeteria) processed through a compression hearing aid. Results revealed that increasing compression ratio caused decreases in ratings on all scales. Increasing release time caused ratings of pleasantness to increase, and ratings of background noise and loudness to decrease. At the 3:1 compression ratio, increasing the release time caused increases in ratings of clarity, pleasantness, and overall impression, and a decrease in background noise. Significant correlations were found between scales. Regression analysis revealed that the contributions of the scales of clarity, pleasantness, background noise, and loudness to the prediction of overall impression differed as a function of the competing noise condition.
An improved ray-tracing algorithm for predicting sound propagation outdoors
Authors: Li Kai Ming , Taherzadeh Shahram , Attenborough Keith
Published: July 2002

A new ray-tracing method for predicting the sound field near a flat impedance ground in a refracting atmosphere is developed that includes the effect of vector wind and turbulence explicitly. Improvements on previous ray-tracing schemes include the use of a generalized Snell’s law, an integration by means of a Gaussian quadrature, and a bracketing method for finding the ray paths. For the turbulence calculations, the interray coherence is determined from turning point heights rather than from integrals along the ray paths. A more efficient algorithm is developed for computing the sound field above an impedance plane in a realistic atmosphere. Despite the inherent limitations of the ray-trace approach, particularly in respect of logarithmic wind profiles, the algorithm is valid over a wide range of practical situations.
Low-frequency whale sounds recorded on hydrophones moored in the eastern tropical Pacific
Authors: Stafford Kathleen M. , Nieukirk Sharon L. , Fox Christopher G.
Published: July 2002

An array of autonomous hydrophones moored in the eastern tropical Pacific was monitored for one year to examine the occurrence of whale calls in this region. Six hydrophones which recorded from 0–40 Hz were placed at 8° N, 0°, and 8° S along longitudes 95° W and 110° W. Seven types of sounds believed to be produced by large whales were detected. These sound types were categorized as either moan-type (4) or pulse-type (3) calls. Three of the moan-type calls, and probably the fourth, may be attributed to blue whales. The source(s) of the remaining calls is unknown. All of the call types studied showed seasonal and geographical variation. There appeared to be segregation between northern and southern hemispheres, such that call types were recorded primarily on the northern hydrophones in the northern winter and others recorded primarily on the southern hemisphere hydrophones in the southern winter. More calls and more call types were recorded on the eastern hydrophones than on the western hydrophones.
Correlation of Shear Behavior of Solutions of Polyisobutylene
Authors: Dunleavy James E. , Middleman Stanley
Published: July 2002

New data are presented for the shear behavior of solutions of polyisobutylene in toluene at 25°C. Five samples (viscosity-average molecular weight range of 105 to 5×106) were studied at shear rates from 1.0 to 3×105 sec−1. Both Couette and capillary viscometers were used in the investigation. The results are correlated by a standard reduced variable plot and compared with earlier data. A method for predicting the viscosity of straight chain polymer solutions from minimal data is discussed.
The Apparent Stress-Deformation Behavior of a Dilute Suspension of Spheres in a Power Model Fluid
Authors: Kremesec Victor J. , Slattery John C.
Published: July 2002

Einstein computed the apparent viscosity of a dilute suspension of neutrally buoyant spheres in an incompressible Newtonian fluid. The objective here is to determine the apparent stress-deformation behavior of a dilute suspension of neutrally buoyant spheres in an incompressible power model fluid. With the assumption that η=mγn−1 describes the apparent viscosity of the continuous phase, our analysis predicts η(sus)=(1+c0x)mγn−1 as the apparent viscosity of the dilute suspension of spheres. Here γ is the shear rate, m and n are the power model parameters for the continuous phase, and x is the volume fraction of spheres in the suspension. The coefficient c0 is defined by the rate of energy dissipation within the neighborhood of a typical sphere in the suspension. In order to evaluate this rate of energy dissipation, the velocity distribution is required. In the limit n=1, corresponding to an incompressible Newtonian fluid, Einstein was able to solve the equations of motion and found c0=2.5. For n≠1, the equations of motion are nonlinear and have not yet been integrated. Instead, we have used previously available principles to calculate upper and lower bounds for the rate of energy dissipation within the neighborhood for a single sphere. This results in upper and lower bounds for c0 as a function of n. The average of these bounds for c0 is compared with available experimental data.
Oscillatory shear of a confined fiber suspension
Authors: Schiek Richard L. , Shaqfeh Eric S. G.
Published: July 2002

Starting from a nonlocal description of the stress in a slender, rigid fiber suspension [Schiek and Shaqfeh (1995)], we calculate the dynamic properties of a free-fiber suspension under oscillatory shear in a very narrow gap. For a fiber suspension, three field quantities including the fluid velocity, the fiber concentration, and the fiber configuration strongly affect the suspension’s behavior. When the width of the gap confining the suspension is of the same scale as a suspended fiber’s length, then all three of the important field quantities change rapidly on that scale. The nonlocal stress equation is coupled to the momentum conservation equation for the fluid velocity and a Fokker–Plank equation for the fiber’s probability density function resulting in a closed set of nonlinear, integrodifferential equations. These equations were solved in the limit of a small Péclet number, where Brownian motion dominates, for arbitrary gap widths and oscillation frequencies. From the calculated stress fields, we obtained the real and imaginary viscosities that one would measure in flow experiments. The dependence of all four dynamic properties on gap width was investigated and we find that below a critical gap width (equivalent to one full fiber length) all dynamic properties undergo dramatic changes. Additionally, as the gap width shrinks, the relaxation time of the suspension was found to decrease, approaching the relaxation time of the pure Newtonian solvent in the limit of zero gap width. Scalings for the relaxation time as a function of small gap width are also presented.
Yield stress measurements of aqueous foams in the dry limit
Authors: Gardiner B. S. , Dlugogorski B. Z. , Jameson G. J. , Chhabra R. P.
Published: July 2002

This paper reports measurements of yield stress of aqueous foams approaching the dry foam limit using a pendulum device. Traditionally, the vane rheometer has been used to measure the yield stress in liquids that exhibit wall slip. However, using the simple and inexpensive pendulum technique, shear rates many orders of magnitudes lower can be achieved. The pendulum was used to observe the change in yield stress for the foam as the gas fraction and bubble size increased. The local gas fraction in the foam was found by measuring the sonic velocity, and the bubble size was determined photographically. Strong support is found for the existence of a true yield stress in aqueous foams at the dry foam limit. Yield stress results, once scaled by σ/〈R〉, agree well with data from previous studies.
Trends in Geographic Disparities in Access to Ambulatory Surgery Centers in New York, 2010 to 2018
Authors: Chatterjee Abhinaba , Amen Troy B. , Khormaee Sariah
Published: October 2022

This cross-sectional analysis evaluates trends in the density, volume, and utilization of ambulatory surgery centers by neighborhood socioeconomic status.
Hygroscopic‐Microgels‐Enabled Rapid Water Extraction from Arid Air
Authors: Guan Weixin , Lei Chuxin , Guo Youhong , Shi Wen , Yu Guihua
Published: October 2022

Sorbent‐based atmospheric water harvesting (AWH) has emerged as a promising decentralized water‐production technology to mitigate the freshwater crisis in arid areas. Hydrogels have been regarded as attractive sorbents due to their high water retention and tailorable polymer–water interactions. Yet, the kinetics of water sorption and desorption at low relative humidity (RH) shall be improved for their practical implementation. Here, hygroscopic microgels (HMGs) composed of hydroxypropyl cellulose (HPC) and hygroscopic salt are reported, which achieve a water uptake of ca. 0.5–0.8 g g−1 at 15–30% RH. HMGs enable rapid sorption–desorption kinetics owing to the short‐distance diffusion in the microgels and hydrophilicity–hydrophobicity switching of the thermoresponsive HPC. To validate the feasibility of HMGs for moisture extraction, a potential daily water collection of up to equivalent 7.9–19.1 L kg−1 at low RH is demonstrated, enabled by 24–36 operation cycles per day based on the material‐level experiments. With renewable raw materials and superior performance, HMGs provide a sustainable approach for rapid moisture extraction in arid climates.
Cartilage Acidic Protein 1 in Plasma Associates With Prevalent Osteoarthritis and Predicts Future Risk as Well as Progression to Joint Replacements: Results From the UK Biobank Resource
Authors: Styrkarsdottir Unnur , Lund Sigrun H. , Thorleifsson Gudmar , Saevarsdottir Saedis , Gudbjartsson Daniel F. , Thorsteinsdottir Unnur , Stefansson Kari
Published: October 2022

Objective

The level of cartilage acidic protein 1 (CRTAC1) in plasma was recently discovered to be associated with osteoarthritis (OA) risk and progression to joint replacement in Iceland. This study was undertaken to validate these findings in an independent population.

Methods

In this study, 1,462 plasma proteins were measured in 54,265 participants from the UK Biobank on the Olink Explore platform. We analyzed the association of plasma proteins with prevalent OA, incident OA, and progression to joint replacement. We assessed the specificity of OA association through comparison of associations with inflammatory joint diseases and with previous joint replacement.

Results

The CRTAC1 protein showed the strongest association with prevalent knee OA (odds ratio [OR] 1.34 [95% confidence interval (95% CI) 1.27, 1.41]) and was associated with hip OA (OR 1.19 [95% CI 1.11, 1.28]). It predicted incident diagnosis of OA in the knee (hazard ratio [HR] 1.40 [95% CI 1.35, 1.46]) and hip (HR 1.25 [95% CI 1.19, 1.31]), as well as progression to joint replacement (HR 1.20 [95% CI 1.08, 1.33] for the knee and HR 1.22 [95% CI 1.08, 1.38] for the hip), while no association was found with inflammatory joint diseases. Individuals in the highest quintile of risk based on CRTAC1 level, age, sex, and body mass index had a 10‐fold risk of knee or hip OA within 5 years compared to those in the lowest quintile. Adding aggrecan core protein (ACAN) and neurocan core protein (NCAN) to the model improved the prediction of OA but not joint replacement. Furthermore, we replicated the association of CUB domain–containing protein 1 with prior joint replacement.

Conclusion

Plasma CRTAC1 is a specific biomarker for OA and a predictor of OA risk and progression to joint replacement. Adding ACAN and NCAN protein levels to the CRTAC1 model improved the prediction of OA.
Dorsal striatal hypoconnectivity predicts antipsychotic medication treatment response in first‐episode psychosis and unmedicated patients with schizophrenia
Authors: Nelson Eric A. , Kraguljac Nina V. , Maximo Jose O. , Armstrong William , Lahti Adrienne C.
Published: October 2022

Introduction

The dorsal striatum, comprised of the caudate and putamen, is implicated in the pathophysiology of psychosis spectrum disorders. Given the high concentration of dopamine receptors in the striatum, striatal dopamine imbalance is a likely cause in cortico‐striatal dysconnectivity. There is great interest in understanding the relationship between striatal abnormalities in psychosis and antipsychotic treatment response, but few studies have considered differential involvement of the caudate and putamen. This study's goals were twofold. First, identify patterns of dorsal striatal dysconnectivity for the caudate and putamen separately in patients with a psychosis spectrum disorder; second, determine if these dysconnectivity patterns were predictive of treatment response.

Methods

Using resting state functional connectivity, we evaluated dorsal striatal connectivity using separate bilateral caudate and putamen seed regions in two cohorts of subjects: a cohort of 71 medication‐naïve first episode psychosis patients and a cohort of 42 unmedicated patients with schizophrenia (along with matched controls). Patient and control connectivity maps were contrasted for each cohort. After receiving 6 weeks of risperidone treatment, patients’ clinical response was calculated. We used regression analyses to determine the relationship between baseline dysconnectivity and treatment response.

Results

This dysconnectivity was also predictive of treatment response in both cohorts.

Discussion

These findings suggest that the caudate may be more of a driving factor than the putamen in early cortico‐striatal dysconnectivity.
The bioresorbable magnesium scaffold (Magmaris)—State of the art: From basic concept to clinical application
Authors: Rola Piotr , Włodarczak Szymon , Doroszko Adrian , Lesiak Maciej , Włodarczak Adrian
Published: October 2022

Since its introduction to clinical practice, coronary artery stent implantation has become a crucial part of the therapy of coronary artery disease (CAD). Despite the undeniable evolution of percutaneous coronary revascularization procedures, drug‐eluting stent (DES) technology shows some limitations. To overcome these limitations bioresorbable vascular scaffolds (BRS) were designed as a vessel‐supporting technology allowing for anatomical and functional restoration of the vessel after the scaffold intended resorption. Various materials have been proposed as the basis of the scaffold backbone. In this narrative review, we present second‐generation magnesium‐alloy bioresorbable scaffold devices (Magmaris; Biotronik). Additionally, we discuss available preclinical and clinical data regarding this new magnesium BRS.
Milder presentation of autosomal dominant fatty acyl CoA reductase 1‐related syndrome: Report of the first Middle Eastern patient and review of the literature
Authors: Almuqbil Mohammed , AbuMelha Ahlam , Albokhari Daniah
Published: October 2022

The FAR1‐related phenotypes caused by the FAR1 gene encodes the peroxisomal protein fatty acyl‐CoA reductase 1 (FAR1), which is required to reduce fatty acids to fatty alcohols used to form ether‐linked alkyl bonds. Biallelic loss‐of‐function variants have been associated with severe psychomotor developmental delay, seizures, cataracts, growth retardation with microcephaly, and spasticity. However, heterozygous variants in FAR1 have been recently linked to a rare genetic disorder called cataracts, spastic paraparesis, and speech delay (CSPSD). Here, we present the first Middle Eastern patient with a de novo pathogenic heterozygous variant in FAR1 identified by exome sequencing (ES) analysis and a detailed overview of the reported clinical phenotypes and genotypes. Our patient represents the milder end of the clinical spectrum, with medication‐free seizures by the first year of life, proper speech and fine motor development, as well as an absence of other previously reported features such as learning difficulties, axial hypotonia, and joint contracture. In addition, she had developmental dysplasia of the hip (DDH) that failed medical management, as well as faltering growth. Our patient adds to the small number of patients recognized to date and expands the clinical spectrum to provide better clinical delineation, improve diagnosis, and develop precision medicine approaches for this disorder.
Aqueous Supercapacitors with Low Cost and High Voltage Enabled by Co‐Solute Crowding Effect of Electrolyte
Authors: Wang Chengshuai , Pu Yunxun , Feng Jianze , Xu Yongtai , Su Kailimai , Yang Bingjun , Lang Junwei , Tian Guangke
Published: October 2022

Developing high‐voltage and environmentally friendly aqueous electrolytes have become a significant trend in supercapacitors (SCs). However, achieving this goal usually requires the use of “water‐in‐salt” (WIS) electrolytes, inevitably increasing manufacturing costs and sometimes posing problems such as environmental pollution. Here, we developed a water/organic solvent hybrid electrolyte (8 m NaClO4‐20 % H2O‐30 % ACN‐50 % PEG‐200) with low cost and high‐voltage capacity using the water‐miscible polymer polyethylene glycol (PEG) as a crowding agent to suppress water activity, and acetonitrile (ACN) as a co‐solvent to improve the ion transport properties. The synergistic advantages of the two co‐solvents allow SCs using this electrolyte to have a high operative voltage window of up to 2.6 V, currently the highest operating voltage for aqueous carbon‐based SCs, excellent capacity retention (over 11000 cycles) and high energy densities (31.2 Wh kg−1). This work provides a promising method for developing green and inexpensive high‐voltage window aqueous electrolytes.
BODIPY‐Equipped Benzo‐Crown‐Ethers as Fluorescent Sensors for pH Independent Detection of Sodium and Potassium Ions
Authors: Sprenger Tobias , Schwarze Thomas , Müller Holger , Sperlich Eric , Kelling Alexandra , Holdt Hans‐Jürgen , Paul Jérôme , Martos Riaño Vera , Nazaré Marc
Published: October 2022

Herein, we report on fluorescent probes which enable the selective quantification of Na+ and K+ in water by fluorescence enhancement (FE) independent of the pH value. These fluorescent probes, so called fluoroionophores, consist of benzo‐crown‐ether derivatives as ionophores, a benzo‐15‐crown‐5 (cf. 5) or a benzo‐18‐crown‐6 (cf. 6), respectively, to selectively bind either Na+ or K+ and a 4,4‐difluoro‐1,3,5,7‐tetramethyl‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) fluorophore. The fluoroionophore 5 shows a FE factor of 7.3 in the presence of 1000 mM Na+ and 6 of 4.7 upon addition of 250 mM K+ in an acidic environment. The dissociation constants (Kd) for 5+Na+ is 276 mM and for 6+K+ is 18 mM enabling the fluorometric determination of biological relevant Na+ or K+ levels. The fluorescence intensities of 5 and 6 were not impacted over a broad range of proton concentrations (pH stable from 3.5 to 9.5) and by the presence of other biologically relevant cations.
A retrospective analysis of Journal of Forecasting: From 1982 to 2019
Authors: Yu Dejian , Sheng Libo , Shi Shunshun
Published: October 2022

This research offers a thorough examination of Journal of Forecasting (JoF) from two angles. On the one hand, this research examines a total of 1403 publications indexed by Web of Science (WoS) from 1982 to 2019. Not only some fundamental statistics like the number of publications and citations each year, the most prolific countries/regions/authors, the highly cited countries/regions/authors, and papers are counted, but content analysis is also done to look at things like document co‐citation clusters and hot and emerging subjects. On the other hand, to illustrate the knowledge flow of JoF that underlies citation connections, this research, which is based on the citing papers of JoF publications, exposes the direction of JoF knowledge dissemination from Economics and Management (i.e., the categories where JoF belongs) to other categories. Moreover, a deeper investigation on semantic clustering of five representative categories is conducted to figure out what topics are the citing papers of JoF are most interested in and whether there is any relationship between the knowledge of these categories and the knowledge produced by JoF. The framework for journal evaluation presented in this research is novel and comprehensive. With this comprehensive perspective, we are able to look back on past accomplishments, identify historical patterns of knowledge spread, illustrate the current course of development, and partially predict future dynamics.