bluuebunny/crossref_metadata_2025 huggingface dataset:
Trapping and Thermal Release of Irradiation Electrons from Polyethylene Terephthalate Films
Authors: Monteith Larry K.
Published: April 2005

Electron irradiation of capacitor-type structures consisting of polyethylene terephthalate films with thin aluminum electrodes can result in a net charge distribution in the dielectric region. Irradiating with a non-penetrating beam of electrons (10–20 keV) and a constant beam current density (5×10−8 A/cm2), the transfer of charge through an external circuit after ceasing the irradiation was correlated with the practical range of the primary electrons. Assuming that the irradiated volume of the polyethylene terephthalate contained a uniformly distributed space charge, the observed values of external charge transfer were used to obtain a minimum value for the trapped irradiation electron density. For the 14-keV irradiation with a practical range approximately one half the thickness of the sample, a value of 1.6×1015 electrons/cm3 was obtained. The corresponding internal electric field near the irradiated electrode was 2×105 V/cm.
Comparison of the Thermal Conductivity, Electrical Resistivity, and Seebeck Coefficient of a High-Purity Iron and an Armco Iron to 1000°C
Authors: Fulkerson W. , Moore J. P. , McElroy D. L.
Published: April 2005

The effects of temperature, purity, magnetic state, and crystal structure on the thermal conductivity, electrical resistivity, and Seebeck coefficient of iron were obtained from measurements on Armco iron (99.5% pure, ρ300/ρ4.2=11.0) and a high-purity iron (99.95% pure, ρ300/ρ4.2=26.2). The most probable determinate errors of the measurements were thermal conductivity ±1.5%, electrical resistivity ±0.1%, and Seebeck coefficient ±0.9%; and larger absolute errors. Where theory permits, the thermophysical properties of iron are discussed in terms of contributing transport mechanisms. The thermal conductivity of iron can be calculated to ±1.5% between 0° and 910°C from electrical-resistivity measurements and the lattice portion of the thermal conductivity determined in this study.
Electrokinetic Phenomena in Boiling ``Freon-113''
Authors: Asch Victor
Published: April 2005

It is shown that the influence of an electrostatic field on the nucleate boiling of ``Freon-113'' is such that bubbles are reduced in size and, more notably, are attracted to the anode of the field. In addition, both alternating and static electric fields produce a pronounced improvement in the peak heat flux of nucleate boiling. Experimental results and photographs are offered as substantiating evidence of these effects and are discussed.
Some Debye Temperatures from Single-Crystal Elastic Constant Data
Authors: Robie Richard A. , Edwards Jerry L.
Published: April 2005

The mean velocity of sound has been calculated for 14 crystalline solids by using the best recent values of their single-crystal elastic stiffness constants. These mean sound velocities have been used to obtain the elastic Debye temperatures θDe for these materials. Models of the three wave velocity surfaces for calcite are illustrated.
Evaporated and Recrystallized CdS Layers
Authors: Böer K. W. , Esbitt A. S. , Kaufman W. M.
Published: April 2005

Heat treatments of evaporated CdS layers in nitrogen containing HCl and traces of oxygen, and providing a transport of CdS and copper are reported. Recrystallization of areas up to several mm2 are observed. At 25°C, the treated layers show mobilities of 140 to 230 cm2/V·sec, photoconductivities of 10−3 to 2×10−1Ω−1cm−1 at 750 ft-c (2600°K white light) with light-to-dark-current ratios of 108–109 and response time (decay) of 300 μsec to 1.2 msec at 100 ft-c. The level distribution and capture cross section for electrons is investigated using spectral distribution, light intensity, and temperature dependence of photoconductivity, thermally stimulated current and response time analyses. Levels at 0.23, 0.43, 0.67, 1.05, and 2.05 eV are observed and the latter three attributed to Cu centers. Compared to other layers and single crystals, these layers show a density of <1012 cm−3 of levels attributed to sulfur vacancies in the range between 0.3 and 0.65 eV and a nondetectable amount of intrinsic defects acting as quenching centers at 0.9 and 1.35 eV. This is explained by a Cu-enhanced recrystallization in a CdS-supplying atmosphere at temperatures (620° to 650°C) below the temperatures otherwise used for crystal growth, and thereby efficient annealing of intrinsic defects.
Electron Energy Distributions in Various Discharges
Authors: Barnes Bentley T.
Published: April 2005

Energy distributions have been derived from the slopes of semilogarithmic plots of the electron current i versus the probe voltage V, and of di/dV. Results are given for dc discharges in inert gases with and without mercury vapor present. Tubes of 34 mm i.d. with filling pressures of 1.0 to 7 Torr and arc currents from 0.2 to 1.5 A were used. At the higher currents, a Maxwellian distribution (MD) was always found for electron energies insufficient for inelastic collision and was sometimes present at higher energies. Deviations from a MD increase with increasing mean energy of the electrons and with increasing distance from the axis of the discharge. The latter effect was enhanced in a tube with neon plus 0.25% Kr in which radial cataphoresis kept the krypton near the tube wall.
Plasma Diagnostics by Thomson Scattering of a Laser Beam
Authors: Gerry Edward T. , Rose D. J.
Published: April 2005

The use of Thomson scattering of a laser beam as a diagnostic technique for laboratory plasmas is discussed. Several potential sources of difficulty in the use of this technique are investigated. Included are simple signal-to-noise considerations based upon photon counting statistics and noise due to plasma radiation, Rayleigh or Raman scattering from neutral particles in the plasma, and scattering from walls, apertures, etc. in the apparatus. Also discussed are other effects which may affect the state of the plasma being measured, namely, free-free absorption which leads to electron heating and free-bound absorption or photo-ionization which can produce additional electrons. Experimental determinations of electron density and temperature in a steady-state hollow-cathode arc plasma, by Thomson scattering of a ruby laser beam, are reported and discussed. These measurements refer primarily to argon plasmas over an electron density range 1013–1014 cm−3 and electron temperature range 3–8 eV. Essential agreement of these measurements with measurements of the same quantities by Langmuir probes is obtained, except for some interesting explainable differences.
Measurements of the Distribution of Defect Introduction Rate with Depth in Silicon Irradiated with 300-keV Electrons
Authors: Hitchcock A. J.
Published: April 2005

The potentialities of a silicon field effect device, having ac and dc fields superimposed on the gate terminals, are investigated for determining the distribution of defect introduction rate with depth. In particular this device is designed for examining defect introduction mechanisms near threshold energies. In these preliminary experiments, 300-keV electrons are incident on devices made from 600-Ω·cm float-zone silicon. When correction is applied for the proximity of the Fermi level to the Ec−0.4-eV defect level, a distribution of a form similar to that obtained by Flicker and Loferski for 500-keV electrons is obtained.
Shape Dependence of the Properties of Ferroelectric Crystals
Authors: Schacher Gordon E.
Published: April 2005

On the basis of elementary molecular field theory, one can predict the transition temperature and Curie constant for a ferroelectric material in terms of the spontaneous polarization. In such a calculation, if migration of free charges did not occur, it is evident that the internal electric field produced by surface depolarization charges should play an important role. Experimental measurements of the transition temperature and Curie constant as a function of sample shape have been performed for several materials and the results are presented for triglycine sulfate. No shape dependence was observed which can be explained by the migration of free charges in the material.
Optical Properties of Thin Metallic Films in Island Form
Authors: Doremus R. H.
Published: April 2005

The optical absorption of island films of gold was studied as a function of island density, as determined from electron micrographs and film thickness. The absorption band resulting from a bounded plasma resonance in the particles was shifted to longer wavelengths as the island density increased. The position of the band was that predicted by the Maxwell Garnett theory for island films with spherical particles. As the particles became smaller the absorption band was broadened because the mean free path of the electrons in them was reduced.
Momentum Transfer Produced by Focused Laser Giant Pulses
Authors: Gregg David W. , Thomas Scott J.
Published: April 2005

The momentum transfer caused by focusing a laser ``giant pulse'' on a surface in a vacuum was studied. A simple pendulum was used for measuring the momentum. Data obtained for Be, C, Al, Zn, Ag, and W show the light intensity which gives maximum momentum transfer per unit of laser energy, and the decrease in momentum transfer as the light intensity is increased. The maximum shock pressures generated in the target materials were estimated to range from 6×105 to 106 bars, depending on the material.
Characteristics of Evaporated Antimony Films as a Function of the Antimony Source
Authors: Sommer A. H.
Published: April 2005

Thin antimony films deposited by evaporation from a PtSb source differ from films produced from elementary antimony in electrical resistance, light transmission, reaction with oxygen, and particle size. Qualitative mass spectroscopic experiments indicate that these differences may be due to antimony evaporating from PtSb predominantly as Sb1 as distinct from the Sb4 aggregates known to evaporate from elementary antimony.
Gas Analysis by Photo-Ionization Mass Spectrometry
Authors: Poschenrieder W. , Warneck P.
Published: April 2005

A photo-ionization mass spectrometer featuring a special 180-deg magnetic analyzer with inclined pole faces is described and its usefulness as a gas analytical tool explored. Ion-source pressures up to 20 μ can be utilized for gas analysis. Higher pressures can be reached but ion-molecule reactions and increasing light absorption cause a nonlinear ion current-pressure relationship. The major advantage of photo-ionization when compared to electron-impact ionization is the simplicity of fragmentation patterns; the major dis-advantage is the lower sensitivity. At 20-μ pressure, spark or resonance light sources used in conjunction with a ½-m monochromator produced peak ion intensities around 5×10−13 A. Although these ion intensities are higher than those reported previously, they are still considerably below the ion intensities commonly produced by electron-impact ion sources.
Analysis of Time-Dependent Creep Phenomena in Single-Crystal MgO
Authors: Rothwell W. S.
Published: April 2005

A set of arguments is presented and used to derive analytical expressions for creep strain-rate time dependence in agreement with experiment. Separate equations are obtained for initial transient creep, the transient electric field effect, and cross-slip controlled-recovery creep. It is shown that a velocity-squared dependence for a cross-slip scattering cross section leads to the time dependence for Andrade creep. The electric field effect is related to interaction of electrons, released from impurity—vacancy complexes, with dislocation-produced neutral vacancy pairs.
Dielectric Anomalies in Silicon Single Crystals
Authors: Rao K. V. , Smakula A.
Published: April 2005

Dielectric constant κ′ and dielectric loss κ″ of Si single crystals with resistivities 12.5, 1000, and 16 000 Ω·cm were measured in the frequency range 103 to 109 cps at temperatures from 4.2°K to 300°K. The dielectric constant at 300°K decreases with frequency and reaches a constant value of 12 above 107 cps. The dielectric loss decreases linearly with frequency in the whole frequency range. The variation of dielectric constant and loss with temperature shows a sharp conductivity-dependent jump at 25°K. Below 25°K the dielectric constant and loss reach constant values. The value of the dielectric constant below 25°K corresponds to the square of refractive index. Between 30° and 80°K the dielectric constant reaches a frequency-independent plateau. The height of the plateau depends on the conductivity of the sample. Above 80°K the dielectric constant is frequency-dependent and increases exponentially with temperature. The irregular variation of dielectric properties is correlated to the formation and trapping of charge carriers.
Distribution of Boron-Induced Defects in Shallow Diffused Surface Layers of Silicon
Authors: Rupprecht H. , Schwuttke G. H.
Published: April 2005

Chemical sectioning of p-type surface layers on silicon is described. The technique is applied to measure the impurity concentration and the defect concentration vs depth in shallow boron-diffused surface layers using electrical measurements and x-ray diffraction microscopy.
Oscillations in the Thermal Cesium Plasma Diode
Authors: Cutler William H. , Burger Peter
Published: April 2005

Oscillations with frequencies corresponding to ion transit times are observed in thermal cesium diodes having parallel-plane construction. Electrons and ions are emitted from heated flat tungsten disks immersed in cesium vapor. Measurements are made with one emitter facing a cold collector and also with two emitters facing each other. Large-amplitude oscillations are observed whenever the collector potential is large enough to draw electron saturation current through the diode. Characteristics of these oscillations are well correlated with computer-simulated results and explained by theory developed earlier. High-frequency bursts during some parts of the low-frequency fluctuations are also observed as predicted from current-vs-time curves of the computer-simulated diode. The electron-rich and ion-rich regimes of the two-emitter diode are found and switching between the two regimes is demonstrated by measuring the ion saturation current with a probe at the middle of the diode.
Thermal and Electrical Transport in InAs-GaAs Alloys
Authors: Hockings E. F. , Kudman I. , Seidel T. E. , Schmelz C. M. , Steigmeier E. F.
Published: April 2005

The thermal conductivity, Seebeck coefficient, and electrical resistivity have been measured as a function of temperature for various impurity concentrations and alloy compositions. Room-temperature measurements of Hall mobility and the optical determination of electron effective masses have been made.

n-type alloys between 50 and 70 mole % InAs, doped with selenium to give room-temperature resistivities of 4 to 8×10−4Ω·cm, give an optimum figure of merit. The maximum figure of merit at 700°K was measured to be 0.98×10−3 deg−1· p-type alloys (30%–70% InAs) doped with zinc gave a maximum figure of merit of only 0.4×10−3 deg−1 at 700°K. The room-temperature Hall mobilities and Seebeck coefficients of the p-type alloys are lower than might be anticipated. The electron effective masses were found to vary uniformly with composition.
Thermionic Converters Operating in the Ignited Mode. Part I: Theoretical Output-Current Characteristics
Authors: Wilkins Daniel R. , Gyftopoulos Elias P.
Published: April 2005

Output current characteristics of thermionic converters are derived without reference to specific elastic and inelastic collision mechanisms, and are expressed in terms of arbitrary plasma electron density and temperature profiles. The general expression for the characteristics indicates that for a given current the output voltage is composed of two parts: (a) a reference output voltage which depends only upon the output current and electrode properties and contains implicitly the effect of electron-electron collisions; and (b) a plasma voltage loss which depends only upon certain average properties of the interelectrode plasma. It is shown that conceptually different models for the interelectrode plasma can lead to similar estimates for the plasma voltage loss and to agreement with experimental output current characteristics. For this reason, it is concluded that the successful correlation of experimental output current-voltage data is necessary but not sufficient to test the validity of a given model for the interelectrode plasma.
Temporal profile of replication of human chromosomes
Authors: Jeon Yesu , Bekiranov Stefan , Karnani Neerja , Kapranov Philipp , Ghosh Srinka , MacAlpine David , Lee Charles , Hwang Deog Su , Gingeras Thomas R. , Dutta Anindya
Published: April 2005

Chromosomes in human cancer cells are expected to initiate replication from predictably localized origins, firing reproducibly at discrete times in S phase. Replication products obtained from HeLa cells at different stages of S phase were hybridized to cDNA and genome tiling oligonucleotide microarrays to determine the temporal profile of replication of human chromosomes on a genome-wide scale. About 1,000 genes and chromosomal segments were identified as sites containing efficient origins that fire reproducibly. Early replication was correlated with high gene density. An acute transition of gene density from early to late replicating areas suggests that discrete chromatin states dictate early versus late replication. Surprisingly, at least 60% of the interrogated chromosomal segments replicate equally in all quarters of S phase, suggesting that large stretches of chromosomes are replicated by inefficient, variably located and asynchronous origins and forks, producing a pan-S phase pattern of replication. Thus, at least for aneuploid cancer cells, a typical discrete time of replication in S phase is not seen for large segments of the chromosomes.
Phosphorylation of a UDP-glucuronosyltransferase regulates substrate specificity
Authors: Basu Nikhil K. , Kovarova Martina , Garza Amanda , Kubota Shigeki , Saha Tapas , Mitra Partha S. , Banerjee Rajat , Rivera Juan , Owens Ida S.
Published: April 2005

UDP-glucuronosyltransferase (UGT) isozymes catalyze detoxification of numerous chemical toxins present in our daily diet and environment by conjugation to glucuronic acid. The special properties and enzymatic mechanism(s) that enable endoplasmic reticulum-bound UGT isozymes to convert innumerable structurally diverse lipophiles to excretable glucuronides are unknown. Inhibition of cellular UGT1A7 and UGT1A10 activities and of [33P]orthophosphate incorporation into immunoprecipitable proteins after exposure to curcumin or calphostin-C indicated that the isozymes are phosphorylated. Furthermore, inhibition of UGT phosphorylation and activity by treatment with PKCε-specific inhibitor peptide supported PKC involvement. Coimmunoprecipitation, colocalization by means of immunofluorescence, and cross-linking studies of PKCε and UGT1A7His revealed that the proteins reside within 11.4 Å of each other. Moreover, mutation of three PKC sites in each UGT isozyme demonstrated that T73A/G and T202A/G caused null activity, whereas S432G-UGT1A7 caused a major shift of its pH-8.5 optimum to 6.4 with new substrate selections, including 17β-estradiol. S432G-UGT1A10 exhibited a minor pH shift without substrate alterations. PKCε involvement was confirmed by the demonstration that PKCε overexpression enhanced activity of UGT1A7 but not of its S432 mutant and the conversion of 17β-[14C]estradiol by S432G-UGT1A7 but not by UGT1A7. Consistent with these observations, treatment of UGT1A7-transfected cells with PKCε-specific inhibitor peptide or general PKC inhibitors increased 17β-estradiol catalysis between 5- and 11-fold, with parallel decreases in phosphoserine-432. Here, we report a mechanism involving PKC-mediated phosphorylation of UGT such that phosphoserine/threonine regulates substrate specificity in response to chemical exposures, which possibly confers survival benefit.
The
Pseudomonas syringae
effector AvrRpt2 cleaves its C-terminally acylated target, RIN4, from
Arabidopsis
membranes to block RPM1 activation
Authors: Kim Han-Suk , Desveaux Darrell , Singer Alex U. , Patel Priyesh , Sondek John , Dangl Jeffery L.
Published: April 2005

Plant pathogenic
Pseudomonas syringae
deliver type III effector proteins into the host cell, where they function to manipulate host defense and metabolism to benefit the extracellular bacterial colony. The activity of these virulence factors can be monitored by plant disease resistance proteins deployed to “guard” the targeted host proteins. The
Arabidopsis
RIN4 protein is targeted by three different type III effectors. Specific manipulation of RIN4 by each of them leads to activation of either the RPM1 or RPS2 disease resistance proteins. The type III effector AvrRpt2 is a cysteine protease that is autoprocessed inside the host cell where it activates RPS2 by causing RIN4 disappearance. RIN4 contains two sites related to the AvrRpt2 cleavage site (RCS1 and RCS2). We demonstrate that AvrRpt2-dependent cleavage of RIN4 at RCS2 is functionally critical
in vivo
. This event leads to proteasome-mediated elimination of all but a membrane-embedded ≈6.4-kDa C-terminal fragment of RIN4. One or more of three consecutive cysteines in this C-terminal fragment are required for RIN4 localization; these are likely to be palmitoylation and/or prenylation sites. AvrRpt2-dependent cleavage at RCS2, and release of the remainder of RIN4 from the membrane, consequently prevents RPM1 activation by AvrRpm1 or AvrB. RCS2 is contained within the smallest tested fragment of RIN4 that binds AvrB
in vitro
. Thus, at least two bacterial virulence factors target the same domain of RIN4, a ≈30-aa plant-specific signature sequence found in a small
Arabidopsis
protein family that may be additional targets for these bacterial virulence factors.
A computer-assisted proof of Saari’s conjecture for the planar three-body problem
Authors: Moeckel Richard
Published: April 2005

The five relative equilibria of the three-body problem give rise to solutions where the bodies rotate rigidly around their center of mass. For these solutions, the moment of inertia of the bodies with respect to the center of mass is clearly constant. Saari conjectured that these rigid motions are the only solutions with constant moment of inertia. This result will be proved here for the planar problem with three nonzero masses with the help of some computational algebra and geometry.
Abelian categories, almost split sequences, and comodules
Authors: Kleiner Mark , Reiten Idun
Published: April 2005

The following are equivalent for a skeletally small abelian Hom-finite category over a field with enough injectives and each simple object being an epimorphic image of a projective object of finite length. (a) Each indecomposable injective has a simple subobject. (b) The category is equivalent to the category of socle-finitely copresented right comodules over a right semiperfect and right cocoherent coalgebra such that each simple right comodule is socle-finitely copresented. (c) The category has left almost split sequences.
Representation dimension: An invariant under stable equivalence
Authors: Guo Xiangqian
Published: April 2005

In this paper, we prove that the representation dimension is an invariant under stable equivalence.
Generating the surface mapping class group by two elements
Authors: Korkmaz Mustafa
Published: April 2005

Wajnryb proved in 1996 that the mapping class group of an orientable surface is generated by two elements. We prove that one of these generators can be taken as a Dehn twist. We also prove that the extended mapping class group is generated by two elements, again one of which is a Dehn twist. Another result we prove is that the mapping class groups are also generated by two elements of finite order.
Gauss-Manin connections for arrangements, III Formal connections
Authors: Cohen Daniel , Orlik Peter
Published: April 2005

We study the Gauss-Manin connection for the moduli space of an arrangement of complex hyperplanes in the cohomology of a complex rank one local system. We define formal Gauss-Manin connection matrices in the Aomoto complex and prove that, for all arrangements and all local systems, these formal connection matrices specialize to Gauss-Manin connection matrices.
A converse to Dye’s theorem
Authors: Hjorth Greg
Published: April 2005

Every non-amenable countable group induces orbit inequivalent ergodic equivalence relations on standard Borel probability spaces. Not every free, ergodic, measure preserving action of

F

2

\mathbb {F}_2

on a standard Borel probability space is orbit equivalent to an action of a countable group on an inverse limit of finite spaces. There is a treeable non-hyperfinite Borel equivalence relation which is not universal for treeable in the

≤
B

\leq _B

ordering.
Valence of complex-valued planar harmonic functions
Authors: Neumann Genevra
Published: April 2005

The valence of a function

f
f

at a point

w
w

is the number of distinct, finite solutions to

f
(
z
)
=
w

f(z) = w

. Let

f
f

be a complex-valued harmonic function in an open set

R
⊆

C

R \subseteq \mathbb {C}

. Let

S
S

denote the critical set of

f
f

and

C
(
f
)

C(f)

the global cluster set of

f
f

. We show that

f
(
S
)
∪
C
(
f
)

f(S) \cup C(f)

partitions the complex plane into regions of constant valence. We give some conditions such that

f
(
S
)
∪
C
(
f
)

f(S) \cup C(f)

has empty interior. We also show that a component

R
0

⊆
R
∖

f

−
1

(
f
(
S
)
∪
C
(
f
)
)

R_0 \subseteq R \backslash f^{-1} (f(S) \cup C(f))

is an

n
0

n_0

-fold covering of some component

Ω
0

⊆

C

∖
(
f
(
S
)
∪
C
(
f
)
)

\Omega _0 \subseteq \mathbb {C} \backslash (f(S) \cup C(f))

. If

Ω
0

\Omega _0

is simply connected, then

f
f

is univalent on

R
0

R_0

. We explore conditions for combining adjacent components to form a larger region of univalence. Those results which hold for

C
1

C^1

functions on open sets in

R

2

\mathbb {R}^2

are first stated in that form and then applied to the case of planar harmonic functions. If

f
f

is a light, harmonic function in the complex plane, we apply a structure theorem of Lyzzaik to gain information about the difference in valence between components of

C

∖
(
f
(
S
)
∪
C
(
f
)
)

\mathbb {C} \backslash (f(S) \cup C(f))

sharing a common boundary arc in

f
(
S
)
∖
C
(
f
)

f(S) \backslash C(f)

.
A countable Teichmüller modular group
Authors: Matsuzaki Katsuhiko
Published: April 2005

We construct an example of a Riemann surface of infinite topological type for which the Teichmüller modular group consists of only a countable number of elements. We also consider distinguished properties which the Teichmüller space of this Riemann surface possesses.
Torsion subgroups of elliptic curves in short Weierstrass form
Authors: Bennett Michael , Ingram Patrick
Published: April 2005

In a recent paper by M. Wieczorek, a claim is made regarding the possible rational torsion subgroups of elliptic curves

E

/

Q

E/\mathbb {Q}

in short Weierstrass form, subject to certain inequalities for their coefficients. We provide a series of counterexamples to this claim and explore a number of related results. In particular, we show that, for any

ε
>
0

\varepsilon >0

, all but finitely many curves
\[

E

A
,
B

:

y
2

=

x
3

+
A
x
+
B
,

E_{A,B} \; : \; y^2 = x^3 + A x + B,

\]
where

A
A

and

B
B

are integers satisfying

A
>

|

B

|

1
+
ε

>
0

A>|B|^{1+\varepsilon }>0

, have rational torsion subgroups of order either one or three. If we modify our demands upon the coefficients to

|

A

|

>

|

B

|

2
+
ε

>
0

|A|>|B|^{2+\varepsilon }>0

, then the

E

A
,
B

E_{A,B}

now have trivial rational torsion, with at most finitely many exceptions, at least under the assumption of the abc-conjecture of Masser and Oesterlé.
Thurston’s weak metric on the Teichmüller space of the torus
Authors: Belkhirat Abdelhadi , Papadopoulos Athanase , Troyanov Marc
Published: April 2005

We define and study a natural weak metric on the Teichmüller space of the torus. A similar metric has been defined by W. Thurston on the Teichmüller space of higher genus surfaces and our definition is motivated by Thurston’s definition. However, we shall see that in the case of the torus, this metric has a different behaviour than on higher genus surfaces.
An Examination of Collaborative Planning Effectiveness and Supply Chain Performance
Authors: Petersen Kenneth J. , Ragatz Gary L. , Monczka Robert M.
Published: April 2005

Many organizations are attempting to gain a competitive advantage by integrating their suppliers more thoroughly into key supply chain processes. This calls for greater strategic and operational cooperation between buyer and supplier firms, often involving some degree of collaborative planning. Advances in information technology are making it possible for firms to share planning information more quickly and easily. This study surveyed purchasing executives whose firms are involved in collaborative planning with suppliers to examine several factors that support effective planning and the impact that effective collaborative planning has on performance in the buying firm. The results show that effective collaborative planning is dependent on the level of trust and the quality of information shared between firms.
Purchasing's Internal Service Performance: Critical External and Internal Determinants
Authors: Fredendall Lawrence D. , Hopkins Christopher D. , Bhonsle Amit
Published: April 2005

This article examines the importance of purchasing's level of internal and external cooperation on its internal service performance and how leadership influences both internal and external cooperation. Results found that visionary leadership increases purchasing's internal and external cooperation, which in turn improves purchasing's internal service performance. The data were obtained from a survey of 2,500 Institute for Supply Management™ members, and were analyzed using structural equation modeling. The implications for practicing managers and for future research are discussed.
Sourcing Indirect Spend: A Survey of Current Internal and External Strategies for Non‐Revenue‐Generating Goods and Services
Authors: Cox Andrew , Chicksand Daniel , Ireland Paul , Davies Tony
Published: April 2005

This article provides evidence about the current sourcing strategies for indirect spend from a survey of 124 organizations. The study found that, despite the recent prominence of reverse auctions and outsourcing options, the most frequently cited external sourcing management approach for indirect spend is long‐term collaboration with preferred suppliers. There was also evidence that indirect spend suffers from a lack of internal support, maverick purchasing, and fragmentation of spend within the organization.
Cortisol and glucose responses after acute stress by net handling in the sparid red porgy previously subjected to crowding stress
Authors: Rotllant J. , Tort L.
Published: April 2005

In red porgy Pagrus pagrus subjected to 3 weeks of chronic stress by crowding, plasma cortisol remained significantly higher in crowded fish compared to controls. There was no significant effect of crowding on plasma glucose levels. When the crowded fish were subjected to an acute handling the plasma cortisol response was similar to that of the uncrowded fish. No significant differences were found between the groups. The changes in plasma glucose following acute handling were also similar in both crowded and uncrowded fish.
Nucleic acid contents and growth of first‐feeding walleye pollock larvae in response to prey densities typical of sub‐Arctic ecosystems
Authors: Canino M. F.
Published: April 2005

The growth, nucleic acid and protein contents of walleye pollock Theragra chalcogramma larvae reared at prey densities of 10, 30, 50, and 500 prey 1‐1 were measured for the first 9 days after the feeding initiation at 6° C. Incremental growth rates of larvae (mm day‐1) were low and variable for the first 7 days after feeding initiation. Growth rates and rates of RNA, DNA, and protein accumulation by larvae reared at 500 prey 1‐1 were positive while those of larvae reared at the lower prey levels did not differ significantly from zero. The RNA/DNA ratio was variable and exhibited no significant trend among food treatments. Estimates of instantaneous protein growth rates ranged from ‐ 6·7 to 13·2% day‐1 at food densities of 10 and 500 prey 1‐1, respectively, and were moderately correlated with larval RNA/DNA ratios (r= 0·628). The results suggest that in situ protein growth rates of first‐feeding pollock larvae may be influenced by prey fields within the range of ambient food densities reported for sub‐Arctic ecosystems.
Reproductive biology of the mosquitofish in a permanent natural lagoon in south‐west Spain: two tactics for one species
Authors: Fernández‐Delgado C. , Rossomanno S.
Published: April 2005

Introduced Gambusia holbrooki in a natural lagoon of southern Spain consisted of two age groups: 1992 cohort, 7‐11 months old and 1993 cohort, <4 months old. In the 1992 cohort, females grew even during the gestation period at about 0·30 mm day‐1. In the 1993 cohort, females displayed a high growth rate (0·55 mm day‐1) and reached reproductive size in a few weeks, but stopped growing when they matured. All the 1992 cohort reproduced from mid‐May to mid‐June, but only 50% of the 1993 cohort reproduced, from mid‐August to mid‐September. Reproducing females were significantly larger in the 1992 cohort (39·8 mm) than in the 1993 one (34·8 mm). The largest 1992 females cohort had reproduced previously; the 1993 cohort had not. The mean dry weight of intra‐ovarian embryos decreased to a minimum immediately before birth. These metabolic costs represented 29·8 and 31·4% of the initial weights of the 1992 and 1993 embryos, respectively. Mean dry weight of full‐term embryo was significantly higher in the 1992 cohort (0·80 ± 0·129 mg; 95% CL) than in the 1993 one (0·70 ± 0·086 mg; 95% CL). With more females in 1992, cohort fecundity was considerably higher (number of embryos=7151; 63%) than in the 1993 (4193; 37%) cohort. The population completed two generations each year (spring and summer). The spring stock grew slower than the summer one but continued to grow during the gestation period, reaching larger final lengths, with more synchronous reproduction and clearer evidence of a second reproductive event. Each reproductive stock displayed its own life‐history characteristics, with significant differences between mean length of reproducing females, growth rate, mean brood size, offspring size, standard fecundity and minimum length at reproduction.
The amount of food ingested in a single meal by rainbow trout offered chopped herring, dry and wet diets
Authors: Ruohonen K. , Grove D. J. , McIlroy J. T.
Published: April 2005

Two‐year‐old 1·5‐kg rainbow trout were held in cages and conditioned by feeding either on low‐fat chopped herring (H trout) or dry pellets (P trout) for 15 weeks. Their satiation amounts were then determined under standard conditions. On a wet weight basis H trout ate 2·5‐3·5 times more food than P trout; this was sufficient to compensate for the high water content of herring and thereby maintain the dry matter intake. When P trout were offered herring (PH trout) they consumed more food than when offered dry pellets but not as much as H trout. Stomach capacity restricted the intake and their dry matter intake was reduced by c. 40%. When H trout were offered dry pellets (HP trout) they adjusted their intake immediately close to the level of P trout although their larger stomachs could have accommodated more than twice this volume of dry food. The return of appetite after a satiation meal was almost linear with time. Appetite increased at c. 556 mg g‐1 body weight h‐1 for H trout and at 142 mg g‐1 bw h‐1 for P trout. The return of appetite in PH trout was significantly slower (c. 370 mg g‐1 bw h‐1) than in H trout; the previous dietary history of the PH trout limited their capacity to process larger volumes of wet food in a single meal. Fish offered dry diet (P and HP trout) had similar rates of appetite return despite their previous feeding history suggesting that the property of the dry feed itself might limit meal size. The total gastric emptying time of diets of similar dry matter content (with and without large amounts of water) was similar, but the delay time before gastric emptying starts tended to be longer for dry diets. Dry pellets appear to impose a demand for water that prolongs the gastric delay. This water demand is met partly by drinking since the trout fed on dry pellets drank significantly more (436 ± 189 mg kg‐1 h‐1) than unfed and herring‐fed trout which drank little or not at all (65 ± 113 and 70 ± 66 mg kg‐1 h‐1 respectively). Dietary water facilitated food processing and increased daily dry matter intake of trout when fed four times a day. When only one satiation meal per day was allowed, dietary water had no effect. It is concluded from this work that, in addition to gastric volume, a short‐term limitation on the size of satiation meals in the rainbow trout is the availability of water to moisturize the food and thus to promote gastric digestion and emptying.
Ontogeny of the digestive tract during larval development of yellowtail flounder: a light microscopic and mucous histochemical study
Authors: Baglole C. J. , Murray H. M. , GOFF G. P. , Wright G. M.
Published: April 2005

The histological development and mucous histochemistry of the alimentary tract in larval yellowtail flounder were studied using light microscopy. Samples were taken when the larvae were first offered food at 3 days post‐hatch, then at 7, 10, 29, 36, and 46 days post‐hatch, at which time they were metamorphosing. Regional partitioning of the digestive tract into the buccal cavity, pharynx, oesophagus, post‐oesophageal swelling (PES), intestine, and rectum was complete by day 10. Goblet cells were present only in the buccal cavity, pharynx and intestine by day 7, but increased in number and distribution as development continued. By day 29, the posterior zone of the oesophagus had a marked increase in goblet cell density and mucosal folding. At the transition from oesophagus to PES/stomach stratified epithelium with goblet cells changed abruptly to a columnar epithelium with no goblet cells. Multicellular glands in the PES of 36‐day larvae allowed it to be defined as a stomach. The distinct brush border of columnar epithelium and the presence of goblet cells characterize the intestine and rectum. All goblet cells throughout the digestive tract were strongly positive for acid mucins as was the luminal layer of the stratified epithelia lining the buccal cavity, pharynx and oesophagus. The PES/stomach epithelium stained weakly for neutral mucins. No mucin staining was associated with the gastric glandular epithelium. The brush borders of the intestine and rectum were strongly positive for combinations of neutral and acid mucins.
Calcium regulation in the freshwater‐adapted mummichog
Authors: Patrick M. L. , Wood C. M. , Marshall W. S.
Published: April 2005

In light of recent findings of an unusual pattern of ionoregulation (high Na+ uptake and negligible Cl‐ uptake) in the freshwater‐adapted mummichog Fundulus heteroclitus, the pattern of Ca2+ regulation was examined. Under control conditions (water Ca2+= 200μEq l‐1), unidirectional Ca2+ influx was 11 ± 4 nEq g‐1 h‐1. Acute variation of external Ca2+ levels revealed a saturable Ca2+ uptake system with a relatively high affinity (Km= 125 ± 36 μEq 1‐1) and a transport capacity (Jmax= 31 ± 4 nEq g‐1 h‐1) comparable to those of other teleosts. Lanthanum (equimolar to [Ca2+]) significantly blocked Ca2+ uptake by 67% whereas magnesium had no effect. Chronic low Ca2+ exposure (50 μEq 1‐1) stimulated Ca2+ uptake almost three‐fold above control values, whereas chronic high Ca2+ exposure (20000 μEq 1‐1) had no effect. Lanthanum and chronic low Ca2+ treatments disturbed the normally positive Ca2+ and Na+ balances of the animals whereas acid‐base balance and ammonia excretion were undisturbed. The results indicate that Ca2+ regulation by the mummichog conforms to the model for freshwater Ca2+ transport whereby chloride cells on the gills take up Ca2+ actively from the water. However, the absence of extra‐intestinal Cl‐ uptake and the recent demonstration of significant Ca2+ uptake by opercular epithelia raise questions about the relative roles of branchial and opercular epithelial chloride cells in freshwater F. heteroclitus.
Cloning and characterization of pejerrey mitochondrial DNA and its application for RFLP analysis
Authors: Yoshizaki G. , Yamaguchi K. , Oota T. , Strüssmann C. A. , Takashima F.
Published: April 2005

Probes were cloned, characterized, and developed for all regions of the mitochondrial DNA (mtDNA) of pejerrey Odontesthes bonariensis to provide the basis for the study of genetic diversity of South American atherinopsinii and to enable species identification from small amounts of tissue. The mtDNA was extracted from liver and cleaved with Eco RI, producing four fragments (7.4, 3.4, 3.1 and 2.9 kb) which were cloned using pUC118 plasmid vectors. Sequence analysis from both ends of the fragments showed that they encode tRNA (Asp, Phe, and Ser‐TGA), 12 S rRNA, cytochrome oxidase (CO) II, NADH 4, 5, and 6, and the D‐loop, and that the relative positions of these genes are identical to those in the mtDNA of other teleosts. A comparison of homology with carp mtDNA nucleotide sequences revealed that tRNA (Phe and Ser‐TGA) and CO II were relatively conserved, whereas the D‐loop region was highly divergent. The cloned mtDNA probes detected mtDNA fragments from about 800 ng of total DNA extracted from liver, muscle, and single embryos of O. bonariensis, and were effective for restriction length fragment polymorphism (RFLP) analysis of Patagonina hatcheri, the most distant atherinopsine relative of pejerrey. The cloned mtDNA probes may be useful for the analysis of genetic diversity and non‐destructive species identification, including the examination of eggs, larvae and juveniles. The mtDNA sequences reported here provide the basis for the design of primers for PCR‐based RFLP analysis.
Mitochondrial DNA differentiation among East and West African Nile tilapia populations
Authors: Rognon X. , Guyomard R.
Published: April 2005

Variation of the ND5/6 mtDNA fragment was studied in six Nile tilapia populations using PCR and RFLP analysis. The observed variation allows a strict discrimination between eastern and western African populations.
Presence of Echinorhinus cookei off central Pacific Mexico
Authors: Aguirre H. , Madrid V. J. , Virgen J. A.
Published: April 2005

On 19 May 1999, the capture of a neonate male of the prickly shark Echinorhinus cookei (377 mm LT) off Michoacán Coast (18°40′N: 103°47′W) was recorded. The prickly shark was found at a depth of 132 m; it was collected over muddy bottom using a trawl net. In Mexico, representatives of this species are scarce off the Pacific Coast; this new record extends the known southern range 261 km from 21°01′N to 18°40′N for the continental coast. The organism was deposited in the ichthyological reference collection of the Centro de Investigación en Alimentación y Desarrollo, A.C, Unidad Mazatlán (catalogue number, CIAD 01–03 Mazatlán). Morphometric and meristic characteristics of the specimen are given.
Effects of transfer to sea water on standard and routine metabolic rates in smolting Atlantic salmon at different stages of seawater adaptability
Authors: Maxime V.
Published: April 2005

Juvenile Atlantic salmon were transferred to sea water at three different times corresponding to different levels of seawater tolerance, i.e. before (A) and at two times (B and C) during the completion of parr‐smolt transformation. Changes in their standard and routine metabolic rates were evaluated by measuring oxygen consumption. The time at which these transfers had been carried out and, consequently, the fish adaptability to sea water affected their post‐transfer metabolism. Indeed, transfer A induced a decrease in mean metabolic rate; under standard conditions, this could be ascribed to a lowered protein turnover. The depression in routine oxygen consumption, which occurred at daylight, was interpreted as an adaptative response to a possible limitation in oxygen supply to the tissues. This limitation would result from a decrease both in the gas diffusing capacity of gills and in oxygen affinity of haemoglobin assumed from changes in plasma ions. Transfers B and C increased standard metabolism; this was probably induced by a stimulation of protein turnover. No outstanding change was noticed in routine oxygen consumption of fish after transfer B. On the other hand, the re‐occurrence of a circadian rhythm of routine metabolism in sea water after transfer C is interpreted as the disappearance of physiological disturbances following a prolonged stay of fish in fresh water.
Riparian land use and accessibility to fishers influence size class composition and habitat use by longfin eels in a New Zealand river
Authors: Broad T. L. , Townsend C. R. , Closs G. P. , Jellyman D. J.
Published: April 2005

Fyke nets were used to sample longfin eels Anguilla dieffenbachii in fourth order stream sites with contrasting riparian land use (native tussock, exotic pasture and pasture plus willows Salix spp.) in Lee Stream, a tributary of the Taieri River, New Zealand. Total lengths (LT) of longfin eels from locations inaccessible to eel fishers were normally distributed whereas those from accessible locations had a non‐normal, positively skewed distribution. Mean LT and body condition were higher in inaccessible than accessible sites, consistent with considerable fishing exploitation in the latter. Mean LT of the fish was greatest in pasture, intermediate in willow and smallest in tussock sites. Larger longfin eels (≥535 mm) were associated with a riffle‐type habitat consisting of shallow, faster‐flowing water with coarse, variable sediment and were taken farther from cover. In contrast, smaller longfin eels were associated with a pool‐type habitat consisting of slower‐flowing, deeper water, with fine, homogenous sediment and were captured closer to cover. This pattern of habitat use differed from some previous reports and probably reflects differences in methodology: fyke nets set over 48 h to sample actively moving longfin eels compared to daytime electric fishing, which samples longfin eels that are more likely to be at rest.
Muscle buffering capacity of yellowtail fed diets supplemented with crystalline histidine
Authors: Ogata H. Y.
Published: April 2005

Juvenile yellowtail Seriola quinqueradiata (initial body mass of 22 g) were fed either a commercial diet (control, diet 1) or diets supplemented with histidine (diet 2), histidine+β‐alanine (diet 3), or histidine+β‐alanine+thyroxine (diet 4), for 6 weeks. The dietary treatment did not affect the final body mass. Free histidine levels of white muscle in the fish fed the diets supplemented with histidine (diets 2‐4) were significantly higher (>62 mmol kg−1 of wet tissue) than that of control group (42 mmol kg−1 of wet tissue). Dietary supplementation of β‐alanine (diet 3) or β‐alanine+thyroxine (diet 4) failed to increase muscle anserine (β‐alanyl‐π‐L.‐histidine) level. Muscle buffering capacity of the range from pH 6·0 to 7·5 of the fish fed the diets 2‐4 (41·6‐42·7 mmol NaOH pH−1 kg muscle−1) reflected the increase of muscle histidine level, having slightly but significantly intensified compared to control fish (36·6 mmol NaOH pH−1 kg muscle−1). Most of the free amino acids other than histidine were significantly lower in the fish fed the diets 2‐4 than in control fish. Thus, crystalline histidine supplemented to diets appears to be deposited in muscular tissue, and consequently enhance muscle buffering capacity in this species.