bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress Dependence of the E1 and E1 + Δ1 Transitions in InSb and GaSb
Authors: Tuomi T. , Cardona M. , Pollak F. H.
Published: July 2007

A double‐beam wavelength modulation technique has been used to measure the effect of static uniaxial compression along the [111] and [001] directions on the E1 and E1 + Δ1 peaks of the reflection spectrum of InSb and GaSb. The splitting of these peaks under [111] stress and the absence of a splitting for [001] stress confirms the Λ symmetry of the corresponding critical points. From the magnitude of the stress‐induced splittings and shifts of these peaks the hydrostatic and shear deformation potentials of the corresponding gaps have been determined.
Etch Pits and Crystal Structure of Tellurium
Authors: Koma A. , Tanaka S.
Published: July 2007

E. Takimoto

The shapes of the asymmetric etch pits produced by slow action of hot sulfuric acid on the cleavage planes of tellurium crystals have been investigated, and a microscopic model is proposed for the formation of the etch pits. The handedness of the spiral chains and the positive direction of the x‐axis of the crystal are determined on the basis of the proposed model. Nuclear magnetic resonance (NMR) has been observed in the same crystals and the observed anisotropy in the chemical shift is in good agreement with the calculated one by Shimizu for both right‐ and left‐handed crystals.
Symmetry Assignments of Two‐Photon Transitions in TlCl
Authors: Fröhlich D. , Staginnus B. , Thurm S.
Published: July 2007

The formalism for the polarization dependence of the two‐photon absorption is extended to include circularly polarized light. Measurements with linearly and circularly polarized light on TlCl allow a unique decomposition of the spectrum into the different symmetry contributions.
Suprastriction in Superconductors
Authors: Kronmüller H.
Published: July 2007

By means of the micromagnetic equations of the superconductivity the deformation of a superconductor below the transition temperature is determined. It is shown that as in ferromagnets the deformation of a superconductor may be divided into spontaneous and forced suprastriction, and the formeffect. The theoretical results are compared with recent experiments.
The Electrodynamic Properties of Alkali Metals for Frequencies Much Smaller than the Debye Frequency
Authors: Czerwonko J.
Published: July 2007

The dielectric constant of polycrystalline alkali metals is studied for a longitudinal as well as a transversal of electromagnetic field. This quantity is computed explicitely in two limiting cases: the quasistatic limit and the quasihomogeneous limit. Only the collisionless region is considered. It is shown that the rf dielectric constant coincides with that for the infrared region in the quasistatic limit whereas both quantities differ in the quasihomogeneous limit. The collisionless region may be attainable rather at helium temperatures and for pure samples. The calculation method consists in application of correlation functions to the microscopic Fermi‐liquid theory.
Interaction of Prismatic Dislocations and Intrinsic Faults
Authors: Clarebrough L. M.
Published: July 2007

Prismatic loops punched from voids in a quenched Cu+9.4 at% Al alloy interact with intrinsic Frank loops to give stable unfaulted regions in the Frank loops bounded by Shockley partials. Two reactions involving dissociation of dislocations with b = 1/2 〈110〉 are identified as nucleating the unfaulted regions. The stability of the unfaulted regions may be attributed to segregation of aluminium to the stacking fault or interaction between a Shockley partial and small defects.
Paramagnetic Studies on the Cu(II) Ion in Single Crystals in Square Planar Coordination
Authors: Biswas P. K. , Sengupta P.
Published: July 2007

Investigations are made to explain the nature of ligand field of Cu(II) complexes in copper bisacetylacetonate and calcium copper acetate hexahydrate having square planar coordination with the neighbouring oxygens, on the basis of the ligand field theory and attempts are made to fit the theoretical expressions of magnetic anisotropy and mean susceptibility with the experimental values in the temperature range 90 to 300 °K, consistently with available optical absorption data and g‐values.
Mössbauer Effect Study of Iron Impurity States in AgCl and NaCl
Authors: Hennig K. , Yung Kim
Published: July 2007

The analysis of the properties of Mössbauer spectra and the conditions of preparing crystals of AgCl and NaCl doped with 57Co enabled us to suggest microscopic interpretation for five different types of chemical associations of cobalt with vacancies and oxygen and OH− impurities. A change of charge from Fe++ to Fe+++ and the reverse change were observed at high temperatures.
A Theory of Dislocation Dynamics
Authors: Gradowczyk M. H.
Published: July 2007

For a continuous distribution of moving dislocations, differential equations are derived that describe crystal flow in terms of the stress tensor, particle velocity, and flux density vectors of the dislocations. Plasticity effects, the non‐existence of an equation of state, elastic waves, and waves of dislocation density are some of the topics discussed.
Mössbauer Measurements of the Debye‐Waller Factor of Gold in Platinum after Low‐Temperature Neutron Irradiation
Authors: Mansel W. , Vogl G. , Vogl W. , Wenzl H. , Barb D.
Published: July 2007

Pt197, which decays with 20 h half‐life to Au197, is produced by irradiation of platinum samples with reactor neutrons at 4.6 °K. At the same time structural lattice defects are formed. Using the Mössbauer effect of Au197, the Debye‐Waller factor of the gold atoms is measured. A reduction of up to approximately 10% in the Debye‐Waller factor is found, which is attributed to irradiation‐produced defects. This behaviour is interpreted in terms of an interaction of defects formed by thermal and fast neutrons. A change of the coupling constant of the Au197 atom to its neighbours is assumed to be responsible for the reduction of the Debye‐Waller factor.
The Electrical Properties of Silicon with Sodium Donors
Authors: Doubrava P.
Published: July 2007

The microphysical parameters of sodium donors in silicon are obtained from an investigation of the temperature dependence of the resistivity and the Hall coefficient and the scattering mechanism of the conduction electrons is determined. The unusual behaviour of the resistivity and the Hall coefficient in the low temperature region is discussed.
Influence of Internal Stress on Thermally Activated Dislocation Motion in the Peierls Potential
Authors: Heinrich R. , Pompe W.
Published: July 2007

An investigation is made of the dependence of thermally activated motion of dislocations in the Peierls potential on internal stresses. In order to compute the mean strain rate the totality of these stresses is taken into account assuming a homogeneous or an inhomogeneous distribution of dislocations. It is found that the increase of the activation volume in the small stress range can be explained. The consequences of this theory with respect to the dependence of flow stress on temperature are discussed.
Measurement of the Total Magnetic Susceptibilities of Metals by NMR
Authors: Smithard M. A. , Wynn V. T.
Published: July 2007

The NMR technique for the measurement of magnetic susceptibilities is extended to include metals in polycrystalline and single crystal forms. Measurements were made on cylindrical samples of copper, silver, gold, aluminium, magnesium, and beryllium. In particular the variation in the magnetic susceptibility of a single crystal of beryllium is obtained as a function of its orientation in the magnetic field. The values for the two principal components of the susceptibility are shown to agree well with those obtained previously by a classical method.
The Kohler Rule of Hall Coefficient in Neutron‐Irradiated Aluminium at 4.6 °K
Authors: Böning K. , Fenzl H. J. , Welter J. M. , Wenzl H.
Published: July 2007

An investigation is made of the range of validity of the Kohler rule for the Hall coefficient of aluminium at 4.6 °K, by introducing structural defects with different concentration and configuration by low temperature reactor irradiation and subsequent annealing. – During irradiation the low field Hall coefficient R0 at first increases rapidly and even changes its sign. But as soon as the electron scattering is predominantly governed by the irradiation induced defects, the Hall coefficient R0 (being now slightly positive) remains constant during further irradiation and the Kohler rule is fulfilled, because then only the concentration of identical defects is enlarged. After step‐annealing again large changes of R0 occur, because the structural defects not only recombine but also rearrange to other configurations with different scattering behaviour.
Lattice Dynamics Model of KNO3 in Its Ferroelectric Phase
Authors: Teng M. K.
Published: July 2007

In order to study the lattice dynamics behaviour of KNO3 through the ferroelectric I → III transition, a model is proposed for the ferroelectric phase III. The frequencies of the three normal low frequency modes are calculated and compared with Raman data. Good agreement between calculated and observed frequencies is obtained. Furthermore, basing on the proposed model, it is suggested that in the I → III ferroelectric transition, the long range electrostatic force, which represents the principal contribution for a softening of the unstable mode, shows only a small temperature dependence in accordance with experimental Raman results.
Stage III Recovery of Copper Heavily Deformed in Torsion
Authors: Polák J.
Published: July 2007

An investigation is made of the stage III recovery of resistivity of copper heavily deformed in torsion at liquid nitrogen temperature. Isochronal and isothermal curves are analysed on the basis of existing theories to explain stage III. The experimental data support the hypothesis of mutual annihilation of interstitial atoms with vacancies; the migrating defect being an interstitial atom, e.g. in dumbbell configuration. The value of the migration energy E = (0.70 ± 0.02) eV and of the radius of the mutual annihilation (five lattice constants) are found.
Etude des spectres d'électroréflexion du GaSb
Authors: Alibert C. , Bordure G.
Published: July 2007

Les spectres d'électroréflexion du GaSb ont été étudiés entre 1,5 et 4,3 eV. Les mesures ont été faites à la température ambiante par la méthode de l'électrolyte. Une hétérojonction GaSb‐Cu2S a permis de faire l'étude en fonction de la température. Nous avons montré que les transitions à 2,02 eV et à 2,48 eV provenaient d'un point critique M1 transverse.
Hartree‐Fock Energy Bands for Krypton
Authors: Lipari N. O.
Published: July 2007

We have computed the Hartree‐Fock energy bands for solid krypton. The method used has been the orthogonalized plane wave (OPW) method. Calculations have been performed at the points Γ, X, L of the first Brillouin zone. Among the most interesting results are: 1. the computed energy gap is of ≈ 15 eV, a value larger than the measured optical gap; 2. the p‐valence bands are relatively wide (≈ 2.8 eV). All these characteristics are in complete agreement with a previous Hartree‐Fock band calculation for argon. We have included many‐body effects using Fowler's theory of electronic polarization.
Infra‐Red Modulation Using Hot‐Electron Faraday Effect in n‐InSb
Authors: Chattopadhyay D. , Nag B. R.
Published: July 2007

The effect of a large static electric field on the infra‐red modulation due to free‐carrier Faraday rotation in n‐InSb has been studied theoretically, taking into account the variation of the effective mass due to carrier heating. The theoretical results are of the same order of magnitude as the experimental ones, but no exact agreement was found. It is further shown, that the contribution of the change in the momentum relaxation time to the alteration of the Faraday rotation is insignificant compared to that arising from the change of effective mass.
Geometric Analysis of Charged Dislocations in the Fluorite Structure
Authors: Brantley W. A. , Bauer Ch. L.
Published: July 2007

Various dislocation configurations are examined in the fluorite structure for the presence of long‐range electrostatic charge assuming slip systems of the {001} 〈110〉 type. It is concluded that neither pure edge or screw dislocations nor jogs and kinks on edge or screw dislocations need necessarily give rise to long‐range charge, although adsorption or desorption of anions and cations could give rise to such charge. Based on these results and existing experimental data, facility of dislocation glide and likelihood of charge transport by dislocations are assessed.
Electron Spin Resonance in Tetracyanoquinodimethan
Authors: Mookherji T. , Kulshreshtha A. P.
Published: July 2007

TCNQ powders show an electron spin resonance with a g‐value of 1.9916 which varies very slightly with temperature. The peak‐to‐peak linewidth is constant at higher temperatures and increases upon cooling below about 260 °K. The temperature variation of the signal intensity gives spin activation energies of 0.06 and 0.03 eV.
Changes in the quality of abalone (Haliotis asinina Linnaeus) packaged under atmospheric air, vacuum and modified atmosphere
Authors: Sanguandeekul Romanee , Siripatrawan Ubonrat , Narakaew Vichaya
Published: July 2007

Changes in the quality of abalone (Haliotis asinina Linnaeus) meat packaged under modified atmosphere (MA) of 40% CO2/30% O2/30% N2, vacuum and atmospheric air in polyvinylidene chloride (PVDC)/nylon/oriented polypropylene (OPP) pouches, and stored at 2 ± 1°C were investigated. Biochemical indices, such as pH, total volatile basic nitrogen (TVB‐N), and trimethylamine (TMA) and sensory evaluation, as well as total plate counts of packaged abalone meat were determined periodically. TMA was not affected by the packaging conditions, and remained low during storage periods. A decrease in pH of the MA packaged abalones during the storage reflected the apparent absorption of CO2. The content of TVB‐N slowly increased in the MA packaged abalone, whereas those stored in atmospheric air markedly increased during the storage. The sensory quality of MA packaged abalones was shown to be acceptable up to 15 days, while atmospheric and vacuum‐packaged abalones were not acceptable after 3 days of storage. Copyright © 2007 John Wiley & Sons, Ltd.
New method for aroma barrier testing
Authors: Vähä‐Nissi M. , Hjelt T. , Jokio M. , Kokkonen R. , Kukkonen J. , Mikkelson A.
Published: July 2007

A new quasi‐isostatic permeation test method has been developed for aroma barrier testing. Aroma concentrations are measured as a function of time, while the compounds diffuse from the source cell containing the model aroma solution through the tested material to the receiving cell. This method is applicable for testing various materials such as uncoated and coated paper/paperboard, and polymer films. The method utilizes automatic gas sampling from the test cells to gas chromatography. Copyright © 2007 John Wiley & Sons, Ltd.
Ensemble‐based chemical data assimilation. I: General approach
Authors: Constantinescu Emil M. , Sandu Adrian , Chai Tianfeng , Carmichael Gregory R.
Published: July 2007

Data assimilation is the process of integrating observational data and model predictions to obtain an optimal representation of the state of the atmosphere. As more chemical observations in the troposphere are becoming available, chemical data assimilation is expected to play an essential role in air‐quality forecasting, similar to the role it has in numerical weather prediction. Considerable progress has been made recently in the development of variational tools for chemical data assimilation. In this paper we assess the performance of the ensemble Kalman filter (EnKF) and compare it with a state‐of‐the‐art 4D‐Var approach. We analyse different aspects that affect the assimilation process, and investigate several ways to avoid filter divergence. Results with a real model and real observations show that EnKF is a promising approach for chemical data assimilation. The results also point to several issues on which further research is necessary. Copyright © 2007 Royal Meteorological Society
ENT challenges at the small scale
Authors: Coulson C. J. , Reid A. P. , Proops D. W. , Brett P. N.
Published: July 2007

Background

In this paper we consider two relatively frequently performed operations in the field of ear, nose and throat (ENT) surgery and consider how they could be improved by using robotic applications. We consider currently available robots and propose theoretical robotic solutions.

Methods

The application of robotic systems for both cochlear implantation and endoscopic sinus surgery was considered. Currently available robotic systems were reviewed and those with potential use in ENT surgery were identified. For aspects of operations where there is no available technology, hypotheses are presented on how robots could help.

Results

Three robotic systems were identified with potential usage in ENT: the Pathfinder™ neurosurgical robot, the Acrobot® knee replacement system and the autonomous smart drill for drilling a cochleostomy.

Conclusions

The challenge for the future of ENT is being able to perform tasks beyond the level of human perception and abilities. The examples presented here demonstrate that microtechnologies could be used to reduce complications, decrease operating time and improve clinical results. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of optimal non‐invasive patient fixation methods for use in robotic hip replacement surgery—an in vitro study
Authors: Schulz A. P. , Tarabolsi M. , Faber A. , Meiners J. , Kammal M. , Mantwill F.
Published: July 2007

Background

A robotic system for the implantation of a total hip arthroplasty (THA) is currently under development. One of the goals of this system is non‐invasive patient fixation, aiding the robotic system by an infrared tracking system. To determine the extent of fixation that can be achieved by non‐invasive methods, an in vitro study was performed.

Methods

In cadaver testing, different non‐invasive fixation methods (Arthrex leg holder with tourniquet mechanism; arthroscopic leg holder with disposable foam inserts; gynaecological leg holder; Goepel knee crutch) were evaluated under load in different directions.

Results

Deviation was measured in the range 0.33–18.1 mm with up to 20 N load. The testing showed the pneumatic leg holder system to provide the highest stability, followed by an arthroscopic leg holder system with foam inserts.

Conclusions

Use of a leg holder with foam inserts produced a stability that should enable tracking of the remaining deviation by the navigation system. We will therefore use this method in our future development of the robotic milling tool. Copyright © 2007 John Wiley & Sons, Ltd.
Curved multi‐tube device for path‐error correction in a needle‐insertion system
Authors: Terayama Motokazu , Furusho Junji , Monden Morito
Published: July 2007

Background

Needle insertion is an important procedure for the diagnosis and treatment of various diseases. A prototype curved multi‐tube device (CMTD) and system for performing computerized correction of path errors during needle insertion is described.

Methods

The CMTD provides two functional modes, the straight‐needle mode and the curved‐needle mode. This study describes the CMTD and path‐error correction, using a prototype needle‐insertion system in a trial with a simple water phantom.

Results

The needle insertion procedure was performed precisely in the centre of an ultrasound image. The CMTD functioned with the inner needle extending properly from its sleeve to correct path errors.

Conclusions

The path‐error corrections by the CMTD in a needle‐insertion system were shown. The system's computer processing can successfully determine the needle path from the ultrasound image and automatically guide the CMTD to the target. Copyright © 2007 John Wiley & Sons, Ltd.
Minimization of needle deflection in robot‐assisted percutaneous therapy
Authors: Abolhassani Niki , Patel Rajni V. , Ayazi Farzam
Published: July 2007

Background

Needle deflection and tissue deformation are two problems encountered during needle insertion into soft, non‐homogeneous tissue. They affect the accuracy of needle placement, which in turn affects the effectiveness of needle‐based therapies and biopsies.

Methods

In this study, a needle is inserted using a robot with two degrees of freedom. The needle is modelled as a flexible beam with clamped support at one end, and its deflection is estimated using online force/moment measurements at the needle base. To compensate for the needle deflection, the needle is axially rotated through 180° . The needle deflection estimation data is used to find the insertion depths at which needle rotations are to be performed.

Results

A bevelled‐tip needle was inserted into animal tissue. The needle deflection at the target was reduced by about 90%. It was observed that minimization of needle deflection reduced tissue deformation. The proposed method reduced needle deflection more than when needle insertion was performed with constant rotation.

Conclusions

Estimating needle tip position using online force/moment measurement improves the accuracy of robot‐assisted percutaneous procedures when imaging feedback is not available. Copyright © 2007 John Wiley & Sons, Ltd.
A prediction‐based nonlinear controller for stabilization of a non‐minimum phase PVTOL aircraft
Authors: Chemori A. , Marchand N.
Published: July 2007

In this paper, a nonlinear prediction‐based control approach is proposed for stabilization of planar vertical take‐off and landing (PVTOL) aircraft. This system has fewer control inputs than degrees of freedom (i.e. under‐actuated) and has unstable zero dynamics (i.e. non‐minimum phase). The proposed control approach is based on partial feedback linearization, which allows the emergence of a completely linearized sub‐state and internal dynamics. Then, optimal trajectories are proposed for the linearized variables, where the optimization objective is to enhance the behaviour and the stability of the internal dynamics. Stability analysis of the closed‐loop system is performed using a graphical tool based on Poincaré's section. The performance of the proposed scheme is illustrated through simulations. Copyright © 2007 John Wiley & Sons, Ltd.
Fast implementations and rigorous models: Can both be accommodated in NMPC?
Authors: Zavala Victor M. , Laird Carl D. , Biegler Lorenz T.
Published: July 2007

In less than two decades, nonlinear model predictive control has evolved from a conceptual framework to an attractive, general approach for the control of constrained nonlinear processes. These advances were realized both through better understanding of stability and robustness properties as well as improved algorithms for dynamic optimization. This study focuses on recent advances in optimization formulations and algorithms, particularly for the simultaneous collocation‐based approach. Here, we contrast this approach with competing approaches for online application and discuss further advances to deal with applications of increasing size and complexity. To address these challenges, we adapt the real‐time iteration concept, developed in the context of multiple shooting (Real‐Time PDE‐Constrained Optimization. SIAM: Philadelphia, PA, 2007; 25–52, 3–24), to a collocation‐based approach with a full‐space nonlinear programming solver. We show that straightforward sensitivity calculations from the Karush–Kuhn–Tucker system also lead to a real‐time iteration strategy, with both direct and shifted variants. This approach is demonstrated on a large‐scale polymer process, where online calculation effort is reduced by over two orders of magnitude. Copyright © 2007 John Wiley & Sons, Ltd.
Model‐based inquiries in chemistry
Authors: Khan Samia
Published: July 2007

In this paper, instructional strategies for sustaining model‐based inquiry in an undergraduate chemistry class were analyzed through data collected from classroom observations, a student survey, and in‐depth problem‐solving sessions with the instructor and students. Analysis of teacher–student interactions revealed a cyclical pattern in which students generated, evaluated, and modified (GEM) hypotheses throughout the course. It is hypothesized that sustained involvement in the GEM cycle contributed to students' engagement with scientific inquiry and model construction and revision. As such, GEM represents a promising approach toward achieving process and content goals in the undergraduate chemistry classroom. © 2007 Wiley Periodicals, Inc. Sci Ed, 91:877–905, 2007
Principle, practice and persona in Isambard Kingdom Brunel's patent abolitionism
Authors: MILLER DAVID PHILIP
Published: July 2007

The nineteenth-century engineering hero Isambard Kingdom Brunel was a prominent patent abolitionist in debates about the patent system in Britain. His opposition is usually regarded as principled, that is, based in liberal laissez-faire opposition to monopolies and to the constraints of bureaucracy. Against this it is argued that Brunel's views on patents evolved. As late as 1840, despite lessons about patents from the bad experiences of his father, Brunel could still consider taking out a patent himself, something that a decade later he denied he had ever contemplated. Brunel's engineering persona, his experiences and conduct of engineering practice were the base from which he eventually formulated principled opposition to the patent system. The paper examines his responses to importunate inventors who pestered him with inventions in the 1840s and elucidates how he dealt with the patented inventions of others that he wanted to use in his projects. It is suggested that for Brunel patent abolitionism was in effect a way of doing business before it became a political cause. The case suggests the value of approaching the history of patents and, by implication, of intellectual property more generally, through detailed examination of practices.
Tomato juice decreases LDL cholesterol levels and increases LDL resistance to oxidation
Authors: Silaste Marja-Leena , Alfthan Georg , Aro Antti , Antero Kesäniemi Y. , Hörkkö Sohvi
Published: July 2007

High dietary intakes of tomato products are often associated with a reduced risk of CVD, but the atheroprotective mechanisms have not been established. This study was conducted to investigate the effects of increased dietary intake of tomato products on plasma lipids and LDL oxidation. The diet intervention included a baseline period, a 3-week low tomato diet (no tomato products allowed) and a 3-week high tomato diet (400 ml tomato juice and 30 mg tomato ketchup daily). Twenty-one healthy study subjects participated in the study. Total cholesterol concentration was reduced by 5·9 (sd10) % (P = 0·002) and LDL cholesterol concentration by 12·9 (sd17·0) % (P = 0·0002) with the high tomato diet compared to the low tomato diet. The changes in total and LDL cholesterol concentrations correlated significantly with the changes in serum lycopene (r0·56,P = 0·009;r0·60,P = 0·004, total and LDL, respectively), β-carotene (r0·58,P = 0·005;r0·70,P < 0·001) and γ-carotene concentrations (r0·64,P = 0·002;r0·64,P = 0·002). The level of circulating LDL to resist formation of oxidized phospholipids increased 13 % (P = 0·02) in response to the high tomato diet. In conclusion, a high dietary intake of tomato products had atheroprotective effects, it significantly reduced LDL cholesterol levels, and increased LDL resistance to oxidation in healthy normocholesterolaemic adults. These atheroprotective features associated with changes in serum lycopene, β-carotene and γ-carotene levels.
Anti-ageing effect of a lactococcal strain: analysis using senescence-accelerated mice
Authors: Kimoto-Nira Hiromi , Suzuki Chise , Kobayashi Miho , Sasaki Keisuke , Kurisaki Jun-ichi , Mizumachi Koko
Published: July 2007

The effects of oral administration of a lactococcal strain on physiological changes associated with ageing were investigated using senescence-accelerated mice (SAM). SAM develop normally, but then show an early onset and irreversible advancement of senescence. SAMP6 is a SAM strain that develops osteoporosis with ageing. Oral administration of heat-killedLactococcus lactissubsp.cremorisH61 (strain H61) to aged SAMP6 mice was associated with reduced bone density loss, a suppression of incidence of skin ulcers and reduced hair loss, compared with controls. Spleen cells from mice fed strain H61 produced more interferon-γ and IL-12 than those from control mice, suggesting that administration of strain H61 altered immune responses. The numbers of viable cells ofBifidobacteriumsp.,Bacteroidessp. andEnterococcussp. in faeces were similar for mice fed the strain H61 and control diets, but counts forStaphylococcussp. were significantly lower (P < 0·05) in mice fed strain H61. Mice fed strain H61 had similar serum concentrations of thiobarbituric acid-reactive substances as in controls, indicating a lack of effect on lipid peroxidation status. Administration of living cells of strain H61 or fermented milk containing strain H61 was also associated with a suppression of incidence of skin ulcers and reduced hair loss. These results indicate that oral administration of strain H61 has the potential to suppress some of the manifestations associated with ageing.
Differential expression and secretion of α1-acid glycoprotein in bovine milk
Authors: Ceciliani Fabrizio , Pocacqua Vanessa , Lecchi Cristina , Fortin Riccardo , Rebucci Raffaella , Avallone Giancarlo , Bronzo Valerio , Cheli Federica , Sartorelli Paola
Published: July 2007

α1-Acid glycoprotein (AGP) is a lipocalin that is produced mainly by the liver and secreted into plasma in response to infections and injuries. In this study, we evaluated AGP isoforms that can be detected in bovine milk. We found that milk-AGP content is made up of at least two isoform groups, a low MW group (44 kDa) that is produced in the mammary gland (MG-AGP), and a higher MW group (55–70 kDa), that is produced by somatic cells (SC-AGP). Identical SC-AGP isoforms can be found both in milk and blood PMN cells. Analysis of the mammary tissue cDNA showed that the sequence of the MG-AGP isoform is identical to that of plasma AGP. Each group contains several proteins with different MWs and different isoelectric points, as shown by 2D-electrophoresis. The glycosylation patterns of these isoforms were analysed by means of specific lectin binding, to evaluate the degree of sialylation, fucosylation and branching. The MG-AGP glycan pattern was identical to plasma AGP produced by the liver. Several differences were detected, however, between plasma and SC-AGP isoforms, the most evident being the strong degree of fucosylation and the elevated number of di-antennary glycans in SC-AGP. Immunohistochemistry showed that AGP is found in all tissues that make up the mammary gland, but that it is most likely produced for the main part by the alveoli.
Screening and enumeration of lactic acid bacteria in milk using three different culture media in Petrifilm™ Aerobic Count plates and conventional pour plate methodology
Authors: Ortolani Maria BT , Viçosa Gabriela N , Beloti Vanerli , Nero Luís A
Published: July 2007

This study aimed to compare Petrifilm™ Aerobic Count (AC) plates and the conventional pour plate methodology using de Mann-Rogosa-Sharpe (MRS), Kang-Fung (KF) and Kang-Fung-Sol (KFS) culture media for screening and enumeration of lactic acid bacteria (LAB) in milk. Suspensions of 10 LAB species in reconstituted powder skim milk and 30 raw milk samples, without experimental inoculation, were tested. For selective enumeration, all samples were previously diluted in MRS, KF and KFS broths and then plated in Petrifilm™ AC and conventional pour plate methodology, using the same culture media with added agar. All plates were incubated at 37°C for 48 h in anaerobic conditions. Differences in the counts were observed only for raw milk samples using KFS in conventional methodology, when compared with the counts obtained from MRS and KF (P⩽0·05). The results showed excellent correlation indexes between both methodologies using the three culture media for LAB suspensions (r=0·97 for MRS, KF and KFS). For raw milk samples, the correlation indexes were excellent (r=0·97, for MRS) and good (r=0·84 for KF, and r=0·82 for KFS), showing some interference in Petrifilm™ AC when supplements were added, especially lactic acid. These results indicate the possibility of using Petrifilm™ AC plates for enumeration of LAB in milk, even with the use of selective supplements.
Evaluation of cholesterol content and impact on antigen exposure in the outer lipid bilayer of adult schistosomes
Authors: TALLIMA H. , HAMADA M. , EL RIDI R.
Published: July 2007

Developing and adultSchistosoma mansoniandS. haematobiumintact worms do not bind specific antibodies, likely because of structural and biochemical modifications of the outer lipid bilayer. We have estimated the amount of cholesterol in the apical membrane of adult schistosomes via extraction with the membrane-impermeable, cholesterol-binding drug, methyl-β-cyclodextrin (MBCD), followed by filipin staining of the worms, and evaluation of the amount of cholesterol released in the medium by a commercially available, enzymatic colorimetric assay. Positive correlations between amount of released cholesterol, MBCD concentration, and worm number and age provided evidence for the sensitivity and validity of the newly developed method. Treatment with 40 mmMBCD for 2 h at 37°C led to total loss of cholesterol from the worm outer membrane, as assessed by filipin staining, and the released cholesterol values were used to estimate the amount of cholesterol per worm and per an approximate surface area unit. Additionally, total depletion of outer membrane cholesterol was associated with exposure of surface membrane antigens to specific antibody binding in 50% and 70% ofS. haematobiumandS. mansoniworms, respectively. These findings together suggest that cholesterol is an essential, but not the sole, factor in sequestration of surface membrane antigens in schistosomes.
FINANCIAL FRAGILITY, INDUSTRIAL DYNAMICS, AND BUSINESS FLUCTUATIONS IN AN AGENT-BASED MODEL
Authors: GATTI DOMENICO DELLI , DI GUILMI CORRADO , GALLEGATI MAURO , GIULIONI GIANFRANCO
Published: July 2007

In this paper we present and discuss a simple financial accelerator agent-based model, whose conceptual core is the interaction of heterogeneous firms and the banking system. Its simplicity notwithstanding, the model is able to replicate through simulations a large number of stylized facts concerning the shape and evolution over time of the distribution of firms' sizes, growth rates, profits, and “bad debt.”
Adaptations to environmental extremes by multicellular organisms
Authors: Islam Mohammed Riajul , Schulze-Makuch Dirk
Published: July 2007

Microbes, particularly Archaea, are well-known for their superb adaptation to extreme environments. However, amazing adaptations to extreme stresses do not only occur in microbes, but also in many multicellular organisms. Examples include tardigrades and their capability to survive freezing to near absolute zero, the Pompeii worm withstanding temperatures of up to 105°C, the Crucian carp remaining active in anoxic conditions for several months, and resurrection plants, which can survive near-complete desiccation. Here, we review some of the cryptobiotic strategies and adaptations exhibited in multicellular organisms, and point out their relevance to astrobiology.
Physical versus biogeochemical interpretations of nitrogen and phosphorus attenuation in streams and its dependence on stream characteristics
Authors: Darracq Amélie , Destouni Georgia
Published: July 2007

We investigate the influence of biogeochemical nutrient attenuation rates versus physical solute travel times on nutrient transport and attenuation in streams with different characteristics. Comparative results indicate smaller biogeochemical in‐stream attenuation rate and greater decrease of this rate with stream depth for phosphorus than for nitrogen. Because physical solute travel times also decrease with stream depth, equally for both nutrients, the resulting relative nutrient mass attenuation becomes essentially independent of stream depth for phosphorus but decreases with stream depth for nitrogen. Coarse interpretation models, without relevant representation of subgrid physical transport variability may lead to systematic misinterpretation of relative nitrogen mass attenuation behavior as a predominantly biogeochemical attenuation rate effect instead of a physical transport time effect. Incorrect understanding and distinction between physical and biogeochemical processes and effects may generally induce misleading cause‐effect conclusions on environmental loads and prevent us from reaching environmental goals of worldwide importance.
Variations of the flank LLBL thickness as response to the solar wind dynamic pressure and IMF orientation
Authors: Šafránková J. , Němeček Z. , Přech L. , Šimůnek J. , Sibeck D. , Sauvaud J.‐A.
Published: July 2007

Several mechanisms have been discussed as candidates for a formation of the low‐latitude boundary layer (LLBL) magnetic reconnection between the magnetospheric and magnetosheath magnetic fields, impulsive penetration of magnetosheath plasma, and viscous/diffusive mixing of plasma populations at the magnetopause. The observed fluctuations of plasma parameters inside the LLBL are attributed either to transient nature of the phenomena forming the layer or to sweeping of deformations of the magnetopause or an inner edge of the LLBL surface along the spacecraft. We are using the Interball‐1/Magion‐4 satellite pair separated by several thousands of kilometers in order to distinguish between spatial and temporal changes of the LLBL plasma population. Observations of LLBL crossings invoked by sudden changes of upstream conditions show that even during a strongly northward interplanetary magnetic field (IMF), the LLBL is relatively thin and follows the compression of the magnetopause induced by changes of the solar wind dynamic pressure. The thickness of the LLBL increases significantly (from a small fraction of RE to more than 1.4 RE) with increase in upstream density and IMF BY component. Our results indicate that the dusk LLBL is supplied by high‐latitude reconnection in the Southern (Northern) Hemisphere, when IMF BY is negative (positive) and lies on open field lines. The change of IMF BY direction leads to brief presence of LLBL plasma outside the magnetopause on magnetosheath field lines. Fluctuations of plasma parameters and magnetic field implicate the presence of surface waves on the inner edge of the LLBL, but no waves were observed on the magnetopause.
Seismogenic permeability, ks
Authors: Talwani Pradeep , Chen Linyue , Gahalaut Kalpna
Published: July 2007

The temporal and spatial pattern of seismicity associated with reservoir water level fluctuations, injection of high‐pressure fluids in deep boreholes, and seasonal groundwater recharge provide a unique setting to study the hydrological properties of the seismogenic fractures. Pore pressure diffusion is primarily responsible for the build up of fluid pressures and the onset of seismicity. The hydrologic property controlling pore pressure diffusion is hydraulic diffusivity c, which is directly related to intrinsic permeability k. By analyzing more than 90 case histories of induced seismicity, we determined the hydraulic diffusivity value of fractures associated with seismicity to lie between 0.1 and 10 m2/s. This range of values of c corresponds to a range of intrinsic permeability values between 5 × 10−16 and 5 × 10−14 m2. We call this range the seismogenic permeability ks. Fractures with ks were found to be associated with Darcian flow. Fractures with permeability less than ks were aseismic, as the pore pressure increase was negligible. In fractures with permeability larger than ks, aseismic non‐Darcian flow was observed. Seismicity was uniquely associated with fractures with seismogenic permeability. Thus seismogenic permeability is an intrinsic property of fractures where pore pressure diffusion is associated with seismicity.
Rupture process of the 1964 Prince William Sound, Alaska, earthquake from the combined inversion of seismic, tsunami, and geodetic data
Authors: Ichinose Gene , Somerville Paul , Thio Hong Kie , Graves Robert , O'Connell Dan
Published: July 2007

Four great earthquakes (1952, 1960, 1964, and 2004) have occurred since seismic monitoring began and only two since the installation of a global seismic network. A reexamination of the 1964 (M 9.2) Prince William Sound (PWS), Alaska, earthquake is timely due to the 2004 Sumatra earthquake because it adds constraints to the potential range of source parameters for these types of infrequent events and aids in the ability to predict the ground motions for other subduction zone including Cascadia. We first measured the durations of high‐frequency energy radiation from teleseismic P wave codas recorded by short‐period World Wide Standardized Seismographic Network (WWSSN SP) instruments to put constraints on the earthquake rupture length. The durations ranged between 250 and 600 s and are shorter in time between azimuths of 190° and 260°. The fault length is estimated to range from 540 to 740 km, rupturing at average speeds of 1.4–2 km/s in a 220°–238° direction. We developed a multiple time window kinematic rupture model for the PWS earthquake from the least squares inversion of teleseismic P waves, tsunami tide gauge records, and geodetic leveling survey observations based on the Green's function technique. We assume three major fault segments for the subduction zone dipping 6‐12° based on geologic data. The subfault size on the megathrust was set to 50 × 50 km. The Patton Bay fault (PBF) imbricate thrust was assigned a 60 dip with a subfault size of 20 × 20 km. We estimated a seismic moment of 5.52 × 1022 N m (Mw9.12). We identified three areas of major moment release, on the PWS segment near Montague and Middleton Islands extending out to the trench, beneath the Portlock anticline on the Cook segment between 58°N fracture zone and the Kodiak‐Bowie seamount chain and finally on the Katmai segment off the coast of Kodiak Island extending to the trench. Our preferred rupture model has a peak slip of 14.9 m along the megathrust and 17.4 m along the PBF. The addition of the PBF resulted in an 8% improvement in residuals and also had a significant effect on the overall slip distribution. Moment release occurred as deep as 50 km depth slab contour near the 350°C isotherm and mantle fore‐arc wedge, which is about 10–20 km deeper than previous coupling depths.
Transports across the 2002 Greenland‐Portugal Ovide section and comparison with 1997
Authors: Lherminier P. , Mercier H. , Gourcuff C. , Alvarez M. , Bacon S. , Kermabon C.
Published: July 2007

The first Ovide cruise occurred in June–July 2002 on R/V Thalassa between Greenland and Portugal. The absolute transports across the Ovide line are estimated using a box inverse model constrained by direct acoustic Doppler current profiler velocity measurements and by an overall mass balance (±3 Sv, where 1 Sv = 106 m3 s−1) across the section. Main currents are studied and compared to the results of the similar Fourex section performed in August 1997 and revisited here. The meridional overturning cell (MOC) is estimated in two different ways, both leading to a significantly lower value in June 2002 than in August 1997, consistent with the relative strength of the main components of the MOC (North Atlantic Current and deep western boundary current). It has been found that the MOC calculated on density levels is more robust and meaningful than when calculated on depth levels, and it is found to be 16.9 ± 1.0 Sv in 2002 versus 19.2 ± 0.9 Sv in 1997. The 2002 heat transport of 0.44 ± 0.04 × 1015 W is also significantly different from the 0.66 ± 0.05 × 1015 W found in 1997, but it is consistent with the much weaker integrated warm water transport across the section than in 1997.
Seasonal variability in the concentration and flux of organic matter and inorganic nitrogen in a semiarid catchment, San Pedro River, Arizona
Authors: Brooks Paul D. , Haas Peter A. , Huth Anne K.
Published: July 2007

Streams and rivers in semiarid environments are characterized by highly variable discharge associated with seasonal precipitation patterns. To characterize how this variability in discharge affects the concentration and flux of organic matter and inorganic nitrogen, we measured discharge and collected water samples in the San Pedro River in southeastern Arizona from April 2001 through September 2002. Mean daily discharge during the study ranged from 2.5 × 103 m3 day−1 to 9.4 × 105 m3 day−1, with low discharge in late June followed shortly thereafter by the highest discharge in July or early August after the onset of monsoon storms. Dissolved Organic Matter (DOM) dominated carbon and nitrogen flux during the nonmonsoon season, while Particulate Organic Matter (POM) dominated flux during the monsoon. The concentrations of Dissolved Organic Carbon and Nitrogen (DOC, DON), and NO3‐N typically increased 2‐ to 10‐fold, while POM increased by 2 to 3 orders of magnitude during the monsoon season. Concurrent increases in concentration and discharge resulted in 96% of the annual organic carbon (DOC + POC) and 97% annual nitrogen (DIN + DON + PON) flux occurring during the monsoon season with the majority of both organic carbon (92%) and total nitrogen (83%) being transported as particulates. These data indicate that POM transported during the monsoon season may be a major source of carbon and nitrogen to the stream ecosystem, potentially fueling heterotrophic activity in sediments and the hyporheic zone after the monsoon season and associated floods have ended.
An efficient conceptual model to simulate surface water body‐aquifer interaction in conjunctive use management models
Authors: Pulido‐Velazquez David , Sahuquillo Andrés , Andreu Joaquín , Pulido‐Velazquez Manuel
Published: July 2007

In conjunctive use management models, the surface and subsurface components must be simultaneously simulated because of the hydraulic interactions and to the combined operating rules inherent to such schemes. When many management alternatives have to be simulated over long time horizon or when optimizing complex large‐scale systems, an efficient tool for surface water body‐aquifer interaction simulation is needed. In this paper, we present a parsimonious conceptual model as an alternative approach to simulate aquifer storage and surface water body‐aquifer interaction for linear aquifers (linear response of head to stresses). The formulation is deduced from a finite difference model preserving its approach of the geometry, boundary conditions, hydrodynamic parameters (heterogeneity), and spatial distribution of the stresses. It does not require any additional assumption. The solution, obtained using eigenvalue techniques, is formulated with an explicit state equation that is a function of time and does not need to be calculated in a sequential way (that is, time is not discretized). The structure of the solution finally deduced allows a simple conceptual interpretation of surface water body‐aquifer interaction phenomenon as the drainage of a number of independent linear reservoirs. The parameters and initial conditions of each linear reservoir are mathematically defined in a univocal way from the original calibrated finite difference model preserving its characteristics. In most practical cases, an accurate solution can be obtained with a reduced number of linear reservoirs. Therefore this multireservoir conceptual definition enables an important reduction in the dimension of the model matrices and provides a straightforward means of incorporating the accuracy of more complex calibrated distributed‐parameter numerical models for simulating surface water body‐aquifer interaction within conjunctive use management models and with a minimum computational cost. Several case studies (synthetic and real world cases) are used to illustrate the applicability of the methodology.