bluuebunny/crossref_metadata_2025 huggingface dataset:
Guidelines for Riparian Vegetative Shade Restoration Based Upon a Theoretical Shaded‐Stream Model1
Authors: DeWalle David R.
Published: November 2008

Abstract: Guidelines for riparian vegetative shade restoration were developed using a theoretical model of total daily radiation received by a shaded stream. The model assumed stream shading by nontransmitting, vertical or overhanging, solid vegetation planes in infinitely long reaches. Radiation components considered in the model were direct beam shortwave on the stream centerline, diffuse atmospheric shortwave, shortwave reflected by vegetation, atmospheric longwave, and longwave emitted by vegetation. Potential or extraterrestrial shortwave irradiation theory was used to compute beam shortwave radiation received at the stream centerline, and view factor theory was used to compute diffuse radiation exchange among stream, vegetation, and atmospheric planes. Model shade effects under clear skies were dominated by reductions in receipt of direct beam shortwave radiation. Model shade effects with cloudy skies were dominated by the “view factor effect” or the decreases in diffuse shortwave and longwave radiation from the atmosphere balanced against increases in longwave radiation from vegetation. Model shade effects on shortwave radiation reflected by vegetation were found to be negligible. The model was used to determine the vegetation height (H) to stream width (W) ratios needed to achieve 50, 75, and 90 % shade restoration for mid‐latitude conditions on clear and cloudy days. Ratios of vegetation height to stream width, for dense nontransmitting vegetation, generally ranged from 1.4 to 2.3 for 75% shade restoration at a mid‐latitude site (40°N). The model was used to showH/Wneeded for E‐Wvs. N‐S stream azimuths, varying stream latitudes between 30° and 50°N, channels with overhanging vegetation, channels undergoing width changes, as well as the limits to shade restoration on very wide channels.
Scattering of a Bessel beam by a sphere: II. Helicoidal case and spherical shell example
Authors: Marston Philip L.
Published: November 2008

In prior work [P. L. Marston, “Scattering of a Bessel beam by a sphere,” J. Acoust. Soc. Am. 121, 753–758 (2007)] the partial wave series for the scattering by a sphere centered on a zero-order Bessel beam was derived. The present work extends the analysis of the far-field scattering to the case of a Bessel beam having an angular dependence on phase. The beam considered is an example of a helicoidal beam where “helicoidal” refers to a type of beam that possesses an axial null and has an azimuthal phase gradient. This type of beam is sometimes also referred to as an acoustic vortex. The beam considered here has a phase ramp equal to the azimuthal angle. In agreement with symmetry arguments given previously, the backward scattering and forward scattering vanish for all frequencies. Some of the resulting modifications of the scattering are illustrated for a rigid sphere and an evacuated steel shell in water. For some directions and choices for the frequency, the calculated scattering by the shell increases when shifting to a helicoidal beam illumination.
Analytical time-domain Green’s functions for power-law media
Authors: Kelly James F. , McGough Robert J. , Meerschaert Mark M.
Published: November 2008

Frequency-dependent loss and dispersion are typically modeled with a power-law attenuation coefficient, where the power-law exponent ranges from 0 to 2. To facilitate analytical solution, a fractional partial differential equation is derived that exactly describes power-law attenuation and the Szabo wave equation [“Time domain wave-equations for lossy media obeying a frequency power-law,” J. Acoust. Soc. Am. 96, 491–500 (1994)] is an approximation to this equation. This paper derives analytical time-domain Green’s functions in power-law media for exponents in this range. To construct solutions, stable law probability distributions are utilized. For exponents equal to 0, 1∕3, 1∕2, 2∕3, 3∕2, and 2, the Green’s function is expressed in terms of Dirac delta, exponential, Airy, hypergeometric, and Gaussian functions. For exponents strictly less than 1, the Green’s functions are expressed as Fox functions and are causal. For exponents greater than or equal than 1, the Green’s functions are expressed as Fox and Wright functions and are noncausal. However, numerical computations demonstrate that for observation points only one wavelength from the radiating source, the Green’s function is effectively causal for power-law exponents greater than or equal to 1. The analytical time-domain Green’s function is numerically verified against the material impulse response function, and the results demonstrate excellent agreement.
Annoyance responses to stable and changing aircraft noise exposure
Authors: Brink Mark , Wirth Katja E. , Schierz Christoph , Thomann Georg , Bauer Georg
Published: November 2008

This article reports the two extensive aircraft noise annoyance surveys subsequently carried out among residents in the vicinity of Zurich Airport in 2001 and 2003 in order to update and validate existing exposure-effect relationships for aircraft noise and annoyance in Switzerland. Logistic and polynomial approximations of the exposure-annoyance relationships for both the years 2001 and 2003 are presented for the Ldn, Lden, and LA,eq24 noise metrics. The results confirm other recently published international research and provide further evidence that community annoyance due to aircraft noise has increased over the past decades. Between the two survey years, a considerable amount of early morning and late evening flight operations have been relocated to use an other runway than before; thus both the effects of a recent step decrease and recent step increase on the exposure-annoyance relationship could be investigated. Residents that experienced a step increase elicited a quite pronounced over-reaction of annoyance which correlated with the magnitude of the change. Two logistic regression models are provided to forecast the effects of changes in exposure during shoulder hours in the early morning and the late evening.
Membrane covered duct lining for high-frequency noise attenuation: Prediction using a Chebyshev collocation method
Authors: Huang Lixi
Published: November 2008

A spectral method of Chebyshev collocation with domain decomposition is introduced for linear interaction between sound and structure in a duct lined with flexible walls backed by cavities with or without a porous material. The spectral convergence is validated by a one-dimensional problem with a closed-form analytical solution, and is then extended to the two-dimensional configuration and compared favorably against a previous method based on the Fourier–Galerkin procedure and a finite element modeling. The nonlocal, exact Dirichlet-to-Neumann boundary condition is embedded in the domain decomposition scheme without imposing extra computational burden. The scheme is applied to the problem of high-frequency sound absorption by duct lining, which is normally ineffective when the wavelength is comparable with or shorter than the duct height. When a tensioned membrane covers the lining, however, it scatters the incident plane wave into higher-order modes, which then penetrate the duct lining more easily and get dissipated. For the frequency range of f=0.3–3 studied here, f=0.5 being the first cut-on frequency of the central duct, the membrane cover is found to offer an additional 0.9dB attenuation per unit axial distance equal to half of the duct height.
Beamwidth control and angular target detection in an echolocating bottlenose dolphin (Tursiops truncatus)
Authors: Moore Patrick W. , Dankiewicz Lois A. , Houser Dorian S.
Published: November 2008

Bottlenose dolphin (Tursiops truncatus) echolocation beams are typically characterized as symmetrical −3 dB beamwidths; however, the functional width of the beam during target detection has not been explored. Angular target detection thresholds of an echolocating dolphin were examined to more fully describe the functional characteristics of the echolocation beam. The dolphin performed an echolocation detection task with its head held in a fixed orientation. Targets were placed 9 m in front of the dolphin [0° position (P0)] and systematically moved right or left until target detection reached chance probability. A 24-element hydrophone array placed 1 m in front of the dolphin was used to measure vertical and horizontal echolocation beamwidths. Detection thresholds were 26° left and 21° right of P0 for a sphere target and 19° left and 13° right of P0 for a cylinder target. Estimates of maximum horizontal and vertical beamwidths ranged up to 40° and 29°, respectively, and exhibited large variability. The dolphin nominally steered the maximum response axis of the echolocation beam up to 18° in the horizontal, 12° in the upward vertical, and 4° in the downward vertical. These results suggest that the dolphin can steer and modify the width of the echolocation beam.
Current-level discrimination and spectral profile analysis in multi-channel electrical stimulation
Authors: Goupell Matthew J. , Laback Bernhard , Majdak Piotr , Baumgartner Wolf-Dieter
Published: November 2008

In experiment 1, six cochlear-implant (CI) listeners discriminated a stimulation pattern eliciting equal loudness for each electrode from a stimulation pattern in which the stimulation at one or more electrodes was increased (peak) or decreased (notch). Three cochlear locations and three bandwidths were tested, without and with level roving. Listeners could always detect peaks but not always notches. Increasing the bandwidth beyond two electrodes produced no improvement in just-noticeable differences (JNDs). JNDs for the basal location were higher than for the apical and middle locations, although listeners had highly individual tendencies. In experiment 2, listeners discriminated changes in the peak heights and notch depths. JNDs for higher peaks were better while JNDs for deeper notches were worse than for experiment 1. In experiment 3, listeners discriminated the electrode position of peaks or notches. JNDs were approximately one electrode. In experiment 4, the first three experiments were repeated with large amounts of level roving. There was no evidence that CI listeners performed an across-channel comparison in these tasks.
Automatic detection of marine mammals using information entropy
Authors: Erbe Christine , King Andrew R.
Published: November 2008

This article describes an automatic detector for marine mammal vocalizations. Even though there has been previous research on optimizing automatic detectors for specific calls or specific species, the detection of any type of call by a diversity of marine mammal species still poses quite a challenge—and one that is faced more frequently as the scope of passive acoustic monitoring studies and the amount of data collected increase. Information (Shannon) entropy measures the amount of information in a signal. A detector based on spectral entropy surpassed two commonly used detectors based on peak-energy detection. Receiver operating characteristic curves were computed for performance comparison. The entropy detector performed considerably faster than real time. It can be used as a first step in an automatic signal analysis yielding potential signals. It should be followed by automatic classification, recognition, and identification algorithms to group and identify signals. Examples are shown from underwater recordings in the Western Canadian Arctic. Calls of a variety of cetacean and pinniped species were detected.
A transient boundary element method model of Schroeder diffuser scattering using well mouth impedance
Authors: Hargreaves Jonathan A. , Cox Trevor J.
Published: November 2008

Room acoustic diffusers can be used to treat critical listening environments to improve sound quality. One popular class is Schroeder diffusers, which comprise wells of varying depth separated by thin fins. This paper concerns a new approach to enable the modeling of these complex surfaces in the time domain. Mostly, diffuser scattering is predicted using steady-state single frequency methods. A popular approach is to use a frequency domain boundary element method (BEM) model of a box containing the diffuser, where the mouth of each well is replaced by a compliant surface with appropriate surface impedance. The best way of representing compliant surfaces in time domain prediction models, such as the transient BEM is, however, currently unresolved. A representation based on surface impedance yields convolution kernels which involve future sound, so is not compatible with the current generation of time-marching transient BEM solvers. Consequently, this paper proposes the use of a surface reflection kernel for modeling well behavior and this is tested in a time domain BEM implementation. The new algorithm is verified on two surfaces including a Schroeder diffuser model and accurate results are obtained. It is hoped that this representation may be extended to arbitrary compliant locally reacting materials.
Perception and production of /r/ allophones improve with hearing from a cochlear implant
Authors: Matthies Melanie L. , Guenther Frank H. , Denny Margaret , Perkell Joseph S. , Burton Ellen , Vick Jennell , Lane Harlan , Tiede Mark , Zandipour Majid
Published: November 2008

Tongue shape can vary greatly for allophones of /r/ produced in different phonetic contexts but the primary acoustic cue used by listeners, lowered F3, remains stable. For the current study, it was hypothesized that auditory feedback maintains the speech motor control mechanisms that are constraining acoustic variability of F3 in /r/; thus the listener’s percept remains /r/ despite the range of articulatory configurations employed by the speaker. Given the potential importance of auditory feedback, postlingually deafened speakers should show larger acoustic variation in /r/ allophones than hearing controls, and auditory feedback from a cochlear implant could reduce that variation over time. To test these hypotheses, measures were made of phoneme perception and of production of tokens containing /r/, stop consonants, and /r/+stop clusters in hearing controls and in eight postlingually deafened adults pre- and postimplant. Postimplant, seven of the eight implant speakers did not differ from the control mean. It was also found that implant users’ production of stop and stop+/r/ blend improved with time but the measured acoustic contrast between these was still better in the control speakers than for the implant group even after the implant users had experienced a year of improved auditory feedback.
A study of high frequency ultrasound scattering from non-nucleated biological specimens
Authors: Falou Omar , Baddour Ralph E. , Nathanael George , Czarnota Gregory J. , Kumaradas J. Carl , Kolios Michael C.
Published: November 2008

The high frequency backscatter from cells with a nucleus to cell volume ratio of 0.50 cannot be adequately modeled as a homogeneous sphere. It was hypothesized that the cytoplasm of such cells is of fluid nature. This work attempts to model the ultrasound backscatter (10–62MHz) from some non-nucleated biological specimens. This was done by measuring the backscatter response from individual sea urchin oocytes and comparing it to theoretical predictions in both the time and frequency domains. A good agreement was found between the experimental and theoretical results suggesting that the non-nucleated oocytes are of fluid nature.
Low-frequency attenuation of acoustic waves in sandy/silty marine sediments
Authors: Pierce Allan D. , Carey William M.
Published: November 2008

Sandy/silty marine sediments are water saturated and consist of diverse tiny rock pebbles. The weight of higher pebbles holds lower pebbles in contact. For low-frequency acoustic disturbances, the no-slip condition and viscosity cause the local water displacement near solid surfaces to be nearly the same as that of the neighboring pebbles. Water farther from surfaces oscillates relative to solid matter because of mass density difference, and viscosity limits the oscillation amplitude. Derived dissipative wave equation predicts attenuation proportional to frequency squared, proportional to the square of the difference of the densities, and inversely proportional to viscosity.
Streaming of vowel sequences based on fundamental frequency in a cochlear-implant simulation
Authors: Gaudrain Etienne , Grimault Nicolas , Healy Eric W. , Béra Jean-Christophe
Published: November 2008

Cochlear-implant (CI) users often have difficulties perceiving speech in noisy environments. Although this problem likely involves auditory scene analysis, few studies have examined sequential segregation in CI listening situations. The present study aims to assess the possible role of fundamental frequency (F0) cues for the segregation of vowel sequences, using a noise-excited envelope vocoder that simulates certain aspects of CI stimulation. Obligatory streaming was evaluated using an order-naming task in two experiments involving normal-hearing subjects. In the first experiment, it was found that streaming did not occur based on F0 cues when natural-duration vowels were processed to reduce spectral cues using the vocoder. In the second experiment, shorter duration vowels were used to enhance streaming. Under these conditions, F0-related streaming appeared even when vowels were processed to reduce spectral cues. However, the observed segregation could not be convincingly attributed to temporal periodicity cues. A subsequent analysis of the stimuli revealed that an F0-related spectral cue could have elicited the observed segregation. Thus, streaming under conditions of severely reduced spectral cues, such as those associated with CIs, may potentially occur as a result of this particular cue.
Auditory brainstem responses to a chirp stimulus designed from derived-band latencies in normal-hearing subjects
Authors: Elberling Claus , Don Manuel
Published: November 2008

In an attempt to compensate for the temporal dispersion in the human cochlea, a chirp has previously been designed from estimates of the cochlear delay based on derived-band auditory brain-stem response (ABR) latencies [Elberling et al. (2007). “Auditory steady-state responses to chirp stimuli based on cochlear traveling wave delay,” J. Acoust. Soc. Am. 122, 2772–2785]. To evaluate intersubject variability and level effects of such delay estimates, a large dataset is analyzed from 81 normal-hearing adults (fixed click level) and from a subset thereof (different click levels). At a fixed click level, the latency difference between 5700 and 710Hz ranges from about 2.0to5.0ms, but over a range of 60dB, the mean relative delay is almost constant. Modeling experiments demonstrate that the derived-band latencies depend on the cochlear filter buildup time and on the unit response waveform. Because these quantities are partly unknown, the relationship between the derived-band latencies and the basilar membrane group delay cannot be specified. A chirp based on the above delay estimates is used to record ABRs in ten normal-hearing adults (20 ears). For levels below 60dB nHL, the gain in amplitude of chirp-ABRs to click-ABRs approaches 2, and the effectiveness of chirp-ABRs compares favorably to Stacked-ABRs obtained under similar conditions.
The effect of signal-temporal uncertainty on detection in bursts of noise or a random-frequency complex
Authors: Bonino Angela Yarnell , Leibold Lori J.
Published: November 2008

This study examined the effect of signal-temporal uncertainty on detection of a 120-ms, 1-kHz tone in the presence of a continuous sequence of 120-ms bursts of either a broadband noise or a random-frequency, two-tone complex. Using the method of constant stimuli, signal-temporal uncertainty was defined as the difference in threshold across temporally uncertain and temporally defined listening conditions. Results indicted an average effect of signal-temporal uncertainty of 2dB for the noise masker compared to 9dB for the random-frequency, two-tone masker. These results suggest that signal-temporal uncertainty may be more detrimental for conditions in which informational masking dominates performance.
STATE COMPLEXITY OF THE SUBWORD CLOSURE OPERATION WITH APPLICATIONS TO DNA CODING
Authors: CÂMPEANU CEZAR , KONSTANTINIDIS STAVROS
Published: November 2008

We are interested in the state complexity of languages that are defined via the subword closure operation. The subword closure of a set S of fixed-length words is the set of all words w for which any subword of w of the fixed length is in S. This type of constraint appears to be useful in various situations related to data encodings and in particular to DNA encodings. We present a few results related to this concept. In particular we give a general upper bound on the state complexity of a subword closed language and show that this bound is tight infinitely often. We also discuss the state complexity of DNA computing related cases of the subword closure operation.
GENE ASSEMBLY MODELS AND BOOLEAN CIRCUITS
Authors: ISHDORJ TSEREN-ONOLT , PETRE ION
Published: November 2008

We propose two different ways to simulate Boolean circuits in the framework of ciliate computations, based on the intramolecular and on the intermolecular gene assembly models with contextual operations applied in a maximal parallel manner. In both cases, the running time and the size of resources of the simulating devices are proportional to the corresponding depth and size of the simulated Boolean circuits.
HOW TO SYNCHRONIZE THE ACTIVITY OF ALL COMPONENTS OF A P SYSTEM?
Authors: BERNARDINI FRANCESCO , GHEORGHE MARIAN , MARGENSTERN MAURICE , VERLAN SERGEY
Published: November 2008

We consider the problem of synchronizing the activity of all the membranes of a P system. After pointing at the connection with a similar problem dealt with in the field of cellular automata where the problem is called the firing squad synchronization problem, FSSP for short, we provide two algorithms to solve this problem. One algorithm is non-deterministic and it works in the time 3h, where h is the height of the tree defining the membrane structure of the considered P system. The other algorithm is deterministic and it works in time 4n + 2h, where n is the number of membranes of the considered P system. Finally, we suggest various directions to continue this work.
EXTENDED SPIKING NEURAL P SYSTEMS WITH DECAYING SPIKES AND/OR TOTAL SPIKING
Authors: FREUND RUDOLF , IONESCU MIHAI , OSWALD MARION
Published: November 2008

We consider extended variants of spiking neural P systems with decaying spikes (i.e., the spikes have a limited lifetime) and/or total spiking (i.e., the whole contents of a neuron is erased when it spikes). Although we use the extended model of spiking neural P systems, these restrictions of decaying spikes and/or total spiking do not allow for the generation or the acceptance of more than regular sets of natural numbers.
ON STATELESS AUTOMATA AND P SYSTEMS
Authors: YANG LINMIN , DANG ZHE , IBARRA OSCAR H.
Published: November 2008

We introduce the notion of stateless multihead two-way (respectively, one-way) NFAs and stateless multicounter systems and relate them to P systems and vector addition systems. In particular, we investigate the decidability of the emptiness and reachability problems for these stateless automata and show that the results are applicable to similar questions concerning certain variants of P systems, namely, token systems and sequential tissue-like P systems.
INDEPENDENCE IN COMPLETE AND INCOMPLETE CAUSAL NETWORKS UNDER MAXIMUM ENTROPY
Authors: MARKHAM MICHAEL J.
Published: November 2008

In an expert system having a consistent set of linear constraints it is known that the Method of Tribus may be used to determine a probability distribution which exhibits maximised entropy. The method is extended here to include independence constraints (Accommodation).

The paper proceeds to discusses this extension, and its limitations, then goes on to advance a technique for determining a small set of independencies which can be added to the linear constraints required in a particular representation of an expert system called a causal network, so that the Maximum Entropy and Causal Networks methodologies give matching distributions (Emulation). This technique may also be applied in cases where no initial independencies are given and the linear constraints are incomplete, in order to provide an optimal ME fill-in for the missing information.
DISPERSION AND FIXATION OF ADENO-ASSOCIATED VIRUS WITH GLUTARALDEHYDE FOR AFM STUDIES
Authors: WANG PENG , WANG XINYAN , YANG HAIJUN , LÜ JUNHONG
Published: November 2008

Sample preparation is an important procedure for atomic force microscope (AFM) studies. However, flexible virus particles have a tendency to aggregate together and are easily compressed during sample preparation or by AFM tip that subsequently hamper studying of virus by AFM. Herein, low concentration chemical reagent of glutaraldehyde (2%, v/v) is pre-mixed in virus suspension that facilitates the dispersion and observation of recombinant serotype 2 adeno-associated virus particles deposited on mica surface with little deformation.
THE STUDY OF HIGH-TEMPERATURE BEHAVIORS OF BRUSH-PLATING NI/NANO-SiO2 COMPOSITE COATING
Authors: XU JIANG , TAO JIE , ZHUO CHENZHI , JIANG SHUYUN
Published: November 2008

In order to improve the high-temperature behaviors of hot work die steel in engineering application, the high-temperature wear and thermal fatigue behavior of brush plating Ni/nano-SiO 2 composite coating have been investigated. The microstructure of Ni/nano-SiO 2 composite coating has been analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM observation of Ni/nano-SiO 2 composite coating has shown that the added SiO 2 particle with an average size of about 20 nm is uniformly distributed in Nickel matrix. The high-temperature wear behavior of Ni/nano-SiO 2 composite coating has been investigated using a ball-on–block test rig. The results from the high-temperature wear behaviors studies indicate that the steady-state friction coefficient and the specific wear rate of Ni/nano-SiO 2 composite coating are lower than that of Cr 12 MoNi steel. The thermal fatigue tests were fulfilled by heating and quenching in water at a cycle period of 2 min. The results of thermal fatigue testing show that brush plating Ni/nano-SiO 2 composite coating can improve thermal fatigue resistance as compared to the Cr 12 MoNi hot rolling tool steel.
LOWER TEMPERATURE FORMATION OF ALUMINA THIN FILMS THROUGH SOL–GEL ROUTE
Authors: RIAZ S. , SHAMAILA S. , KHAN B. , NASEEM S.
Published: November 2008

Bayerite sol is spun onto single crystal Si substrate, after synthesis and optimization, to obtain films of thickness ~ 0.2 μm. The deposited films are room temperature dried and then heated up to a temperature of 350°C in order to obtain Al 2 O 3. Surface and structural changes, during heating, are observed with optical microscopy. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used for post-treatment analyses/characterization. The as-deposited and heated samples' surfaces are smooth as seen with optical and scanning electron microscope in case of optimized conditions. XRD patterns show the change from amorphous to crystalline behavior of these films when heated under various conditions. The most stable form of aluminum oxide, i.e. α- Al 2 O 3, is obtained when samples are heated up to a temperature of as low as 350°C. The thin films are also deposited onto sodalime glass substrates in order to confirm Al 2 O 3 formation through band gap probing. Photoconduction is used to find the energy band gap, which comes out to be 4.7 eV; lower value is correlated to the defect induced states in the band gap.
STUDY ON CLUSTER FORMATION OF POLY 2-HYDROXYETHYL METHACRYLATE FUNCTIONALIZED SINGLE-WALLED CARBON NANOTUBES
Authors: ASHOK KUMAR NANJUNDAN , KIM SUNG HUN , KIM JONG TAE , LIM KWON TAEK , JEONG YEON TAE
Published: November 2008

Cluster-like network structures of single-walled carbon nanotubes (SWNTs) were synthesized by chemical grafting poly 2-hydroxyethyl methacrylate (polyHEMA) to the sidewalls of SWNTs. Acid chloride-functionalized tubes were coupled with commercially available HEMA monomer, which was in turn polymerized using a radical initiator. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to identify the surface changes on the nanocomposites. Microscopic observations of the nanotube complexes by field emission scanning electron microscopy (FE-SEM) show that the tubes were dispersed and formed cluster-like network, branched structures with less bundling, thus, strongly suggesting a firm coating of the polymer on nanotube walls. The coating was further confirmed by transmission electron microscopy. The thermal properties of the nanotube complex as studied by thermal gravimetric analysis (TGA) revealed that coating enhanced stability of the complex, when compared to that of bulk polyHEMA and pristine SWNTs. The nanotube complexes showed excellent suspension stability when dispersed in organic solvent.
THE GIANT MAGNETOSTRICTION AND MAGNETIC PROPERTIES OF THE AMORPHOUS ALTERNANT [Tb/Fe/Dy]n AND [Fe/Tb/Fe/Dy]m NANO-MULTILAYER FILMS
Authors: LI X. D. , PAN L. K. , ZHAO Z. J. , HUANG S. M. , CHEN Y. W. , SUN Z.
Published: November 2008

The magnetic properties and giant magnetostriction effect (GMS) of the amorphous alternant [ Tb / Fe / Dy ]n (named S1) and [ Fe / Tb / Fe / Dy ]m (named S2) nano-multilayer films have been studied. The magnetic hysteresis loops show that easy magnetic direction changes from perpendicular to the film plane (S1) to parallel to the film plane (S2). S2 has better soft magnetic properties and low-field giant magnetostriction effect than that of S1, due to the exchanging interaction between the hard GMS layer and the soft layer Fe . The different magnetic behavior is explained by considering the nature of the magnetization process, i.e. domain-wall motion and spin rotation.
A DENSITY-FUNCTIONAL-THEORY STUDY OF MAGNETIC ANISOTROPIES OF ONE-DIMENSIONAL Ni CHAINS AND MAGNETISM OF 3D TRANSITION METALS ON Au(110)-(1 × 2) SURFACE
Authors: FAN WEI , GONG XIN-GAO
Published: November 2008

Based on the Density Functional Theory (DFT) with noncollinear-magnetism formulations, we have calculated the magnetism of single 3d transition-metal atoms and the magnetic anisotropies of supported Ni chains on the Au(110)-(1 × 2) surface. Our results for single absorbed 3d transition-metal atoms show that the surface relaxations enhance the orbital moments of left-end elements (Ti, V) and quenches the orbital moments of right-end elements (Fe, Co, Ni) on the Au(110)-(1 × 2) surface. The magnetic anisotropies of Ni atomic chains on the surface are closely related to orbital quenching. The easy magnetized axes change from the direction parallel to the chains to the direction perpendicular to the Ni chains when they absorb on the surface.
AVRAMI–KOLMOGOROV–JOHNSON–MEHL KINETICS FOR NANOPARTICLES
Authors: ZHDANOV VLADIMIR P.
Published: November 2008

In the conventional Avrami–Kolmogorov–Johnson–Mehl model, the reaction or phase transition occurring in the 2D or 3D infinite medium is considered to start and proceed around randomly distributed and/or appearing nucleation centers. The radius of the regions transformed is assumed to linearly increase with time. The Monte Carlo simulations presented, illustrate what may happen if the transformation takes place in nanoparticles. The attention is focused on nucleation on the regular surface, edge and corner sites, and on the dependence of the activation energy for elementary reaction events on the local state of the sites.
Higher-Level Hand Motor Function in Aging and (Preclinical) Dementia: Its Relationship with (Instrumental) Activities of Daily Life – A Mini-Review
Authors: Scherder Erik , Dekker Welmoed , Eggermont Laura
Published: November 2008

A causal relationship between physical activity such as walking and cognitive functions – particularly executive functions and memory – has been observed in elderly people with and without dementia. Executive functions play an important role in the (instrumental) activities of daily life [(I)ADL]. However, a close relationship has also been found between motor activity of the upper limb, particularly the hand, and (I)ADL. Indeed, in aging, a decline in hand motor function is related to a decrease in (I)ADL, an increase in functional dependency, admission to a nursing home, and even mortality. This review begins by addressing clinical studies on the effect of age on higher-level hand motor activity. It then discusses higher-level hand motor function in age-related neurodegenerative diseases such as mild cognitive impairment, Alzheimer’s disease and vascular dementia. It concludes by discussing the contribution of higher-level hand motor function assessment to the diagnosis of the various subtypes of (preclinical) dementia and by addressing the clinical relevance of studying higher-level hand motor function, procedural learning, and (I)ADL in aging and (preclinical) dementia.
Promoter Methylation and Polymorphisms of the MGMT Gene in Glioblastomas: A Population-Based Study
Authors: Zawlik Izabela , Vaccarella Salvatore , Kita Daisuke , Mittelbronn Michel , Franceschi Silvia , Ohgaki Hiroko
Published: November 2008

O6-methylguanine-DNA methyltransferase (MGMT) is a repair enzyme that removes promutagenic O6-methylguanine adducts in DNA, to protect cells from acquisition of G:C→ A:T mutations. MGMT promoter methylation and polymorphisms may affect MGMT expression and activity. In the present study, we assessed MGMT promoter methylation and polymorphisms (Leu84Phe, Ile143Val, c.–56C>T) in 371 glioblastomas diagnosed at the population level. MGMT methylation was observed in 165 (44%) glioblastomas, with a higher frequency in females than males (53 vs. 39%; p = 0.0106) and in secondary than primary glioblastomas (73 vs. 43%; p = 0.0074). The frequency of TP53 G:C→A:T mutations in glioblastomas with MGMT methylation was 25%, which was significantly higher than that in glioblastomas with MGMT methylation (16%; Fisher exact test; p = 0.0385). MGMT 143 Val allele in glioblastomas was significantly less frequent than in a healthy European Caucasian population, and was associated with longer survival than those with the MGMT 143 Ile allele (hazard ratio 0.70; 95% CI 0.48–1.01). These results suggest that MGMT methylation may be associated with susceptibility to acquire TP53 G:C→A:T mutations, and that MGMT polymorphisms may affect the risk and prognosis of glioblastomas.
Trends in Head Injury Incidence in New Zealand: A Hospital-Based Study from 1997/1998 to 2003/2004
Authors: Barker-Collo Suzanne L. , Wilde Nancy J. , Feigin Valery L.
Published: November 2008

Traumatic brain injury (TBI) is a leading cause of disability and death in young adults. Globally, the incidence of TBI hospitalizations is estimated at 200–300 people per 100,000 annually. Using a national health database, we examined the incidence of TBI-related hospital discharges (including 1-day stays) to New Zealand Hospitals from 1997/1998 to 2003/2004. Crude annual hospital-based incidence rates for the total population ranged from 226.9 per 100,000 in 1998/1999 to a high rate of 349.2 in 2002/2003. There was a noticeable increase in rates with the change from ICD-9 to ICD-10 diagnostic codes and there was also disparity in incidence rates according to ethnicity, age and gender. Crude annual hospital-based incidence rates for males and females in Maori (689/100,000 and 302.8/100,000 person-years) and Pacific Island populations (582.6/100,000 and 217.6/100,000 person-years) were much higher than those for the remaining population (435.4/100,000 and 200.9/100,000 person-years), particularly for males. The overall age-standardized hospital- based incidence rate for 2003/2004 was 342 per 100,000 per year (95% CI = 337–349/100,000), and 458 per 100,000 per year for Maori (95% CI = 438–479/100,000) with Maori males experiencing a peak in incidence between 30 and 34 years of age that was not evidenced for the wider population. Standardized hospital-based incidence rates for the total population and for Maori by age, gender and ICD-10 diagnostic codes are also examined.
Stroke Case Fatality Shows Seasonal Variation Regardless of Risk Factor Status in a Japanese Population: 15-Year Results from the Takashima Stroke Registry
Authors: Turin Tanvir Chowdhury , Kita Yoshikuni , Rumana Nahid , Murakami Yoshitaka , Ichikawa Masaharu , Sugihara Hideki , Morita Yutaka , Tomioka Nobuyoshi , Okayama Akira , Nakamura Yasuyuki , Abbott Robert D. , Ueshima Hirotsugu
Published: November 2008

Background: Seasonal variation in fatality caused by stroke was examined using 15 years of data from a stroke registry of a Japanese population. Methods: Data were obtained from the Takashima Stroke Registry, which covers approximately 55,000 residents in central Japan. There were 1,650 registered cases of first-ever stroke between 1988 and 2002. 7- and 28-day fatality rates and 95% confidence intervals were calculated for winter, spring, summer and autumn. After adjusting for gender, age at onset and risk factors, the hazard ratios for fatal strokes in winter, spring and autumn were calculated, with summer serving as the reference. Results: For cerebral infarction, the highest 7- and 28-day fatality rates occurred during spring and winter, where they were more than double the rate during summer. The severest strokes were also more likely to occur during winter and spring. A high spring and winter hazard ratio for 28-day mortality was present in both lacunar and nonlacunar subtypes, in both genders and in subjects <65 and ≥65 years of age. No apparent seasonal pattern was observed for cerebral hemorrhage or subarachnoid hemorrhage. The spring and winter excess fatality persisted even after adjusting for age, gender and risk factors. Conclusion: Patients who suffer an ischemic stroke during winter or spring have a poorer prognosis. Further investigation is needed to determine the factors that explain this excess risk.
Sites and Mechanisms of the Excretion of Allantoin by the Rat Kidney
Authors: Roch-Ramel Françoise , Diezi-Chomety Françoise , Lenoir Régine , Kramp Ronald
Published: November 2008

14C-allantoin is freely filtered into glomerular fluid and both secreted into and reabsorbed from tubule fluid, as disclosed by clearance, micropuncture, microinjection, surface drop deposition, tissue analysis, and in vitro slice methods. Secretion, resulting in proximal fractional deliveries of 1.12 ± 0.05 (n = 53), was inhibited by PAH, probenecid and salicylate, but neither by creatinine nor by N1-methylnicotinamide. Reabsorption along the whole nephron resulted in a fractional excretion between 0.8 and 0.9 in the nondiuretic state which increased above unity at high rates of urine flow.
Urinary Protein Excretion in Normal Mice
Authors: Kelley Vicki E. , Cavallo Tito
Published: November 2008

Levels of protein excretion were assessed in female and male mice for 12 consecutive months. In females, protein excretion was low and relatively uniform throughout the study. By contrast, in males, there was considerable variation in protein excretion and more protein was excreted at all times; proteinuria more than doubled by 3 and peaked by 5 months, returning to lower levels by 13 months. These studies (a) provide detailed data on levels and variations of protein excretion in mice considering sex and age, (b) establish values of protein excretion above which pathologic proteinuria would be expected to occur, and (c) are consonant with the notion that, in mice, physiologic proteinuria is, at least in part, gonadal hormone-related.
Structural Changes after Infusion of Mannitol in the Cat Kidney
Authors: Yun John C.H. , Kenney Richard A.
Published: November 2008

Structural changes after the infusion of mannitol were examined in the kidney of the cat. Infusion of mannitol causes a decrease in the size of the glomerular vascular tuft and an increase in the luminal diameter of the proximal convoluted tubules. The number of nonpatent proximal tubules is decreased following the infusion of mannitol. Infusion of mannitol also causes changes in the ultrastructure of the proximal convoluted tubular cells: vacuolization and extrusion of the cytoplasm, and loss of and damage to the microvilli. It is concluded that changes in the structure of the nephron may contribute to the diuresis and natriuresis brought about by the infusion of mannitol.
Effects of Albumin and Mannitol on Blood Flow Autoregulation in Isolated Dog Kidneys
Authors: Kleinman Jack G. , Buffington Gary A. , Luber Howard J. , Ellis Byron P. , Itskovitz Harold D.
Published: November 2008

In isolated blood-perfused dog kidneys, additions of bovine serum albumin abolished blood flow autoregulation. Replacing the perfusate with fresh blood or adding mannitol restored autoregulation. When mannitol alone was added, autoregulation also decreased, but less than with albumin alone, and subsequent addition of albumin abolished autoregulation. Diminished distal water and electrolyte delivery, subcapsular renal pressure, and vascular reactivity to angiotensin II occurred with albumin addition. Mannitol ameliorates the effect of albumin on autoregulation by increasing intrarenal tissue pressure and distal delivery.
Effect of Indomethacin on Renal Function and Plasma Renin Activity in Conscious Dogs
Authors: Yun John C.H. , Bartter Frederic C. , Kelly Gerald D. , Tate John
Published: November 2008

The effect of indomethacin on plasma renin activity (PRA) and sodium excretion was examined in normal conscious dogs before and during water diuresis. PRA did not show significant change with the administration of indomethacin (5 mg/kg): PRA was 5.00 ± 1.69 ng/ml/h during control periods and was 5.56 ± 1.93 ng/ml/h (p > 0.1) 80 min after the administration of indomethacin. Mean arterial blood pressure (MABP) was 100.5 ± 5.1 mm Hg during control periods and was 93.3 ± 6.6 mm Hg (p > 0.1) 80 min after the administration of indomethacin. Administration of indomethacin into these dogs undergoing water diuresis did not change the clearance of either inulin or p-aminohippurate. Sodium excretion (UNaV) showed a slight but not significant decrease after treatment with indomethacin (p > 0.1). UNaV was 89.7 ± 22.9 µEq/min during control periods and was 73.2 ± 12.6 µEq/min 80 min after the administration of indomethacin. The data suggest that renin secretion and sodium excretion in normal conscious dogs are not influenced by indomethacin.
Newly Synthesized Proteins in Rat Glomerular Fractions
Authors: Minuth Will W. , Kriz Wilhelm
Published: November 2008

Isolated glomerular preparations are known for their capability to synthesize proteins. A thorough biochemical separation and characterization of newly synthesized proteins, however, is lacking. In this study isolated glomeruli from rat kidney (enriched by sieving technique alone or by a combination of sieving and subsequent further enrichment by either sucrose or Ficoll discontinuous centrifugation) were incubated for various periods with protein and glycoprotein precursors. The synthesis of soluble and membrane-bound proteins was studied. Separation of glomerular proteins was carried out by means of SDS-electrophoresis in 6 M urea. The radioactivity of newly synthesized proteins was determined by the scintillation technique. In the leucine-incubated glomeruli, a broad spectrum of newly synthesized monomer proteins ranging from 90,000 to 25,000 daltons was detected, whereas in the glucosamine and galactose incubated glomeruli a synthesis of glycoproteins of molecular weights ranging mainly between 90,000 and 60,000 daltons could be observed. Most of the radioactivity incorporated into isolated glomeruli was regained in 600 g (containing basement membrane with residual mesangial/endothelial nuclei and cellular debris) and 12,000 g (membrane structures and mitochondria) pellets, indicating that most of the newly synthesized proteins are membrane bound. A component of newly synthesized glycoprotein (72,000 daltons) could be extracted by mild NaCl treatment and is partly soluble in desoxycholate. Further experiments utilizing isoelectrofocusing and two-dimensional electrophoresis are in progress.
Urinary 3-Hydroxyproline in Renal Disease
Authors: Chanard Jacques , Szymanowicz Anton , Brunois Jean-Pierre , Toupance Olivier , Birembaut Philippe , Borel Paul Jacques
Published: November 2008

The renal excretion of 3-hydroxyproline (3-HYP), an isomer of 4-hydroxyproline (4-HYP) found 6–10 times more in basement membrane collagen than in interstitial collagen, was investigated in control subjects and in 58 adult patients with various kidney diseases. With the exception of polykystic renal disease, all the nephropathies were investigated by renal biopsy. In normal adult subjects urinary 3-HYP was 12.5 + 3.5 (SD) µmol/24 h, 4-HYP 226 ± 62 µmol/24 h and the percentage ratio 3-HYP/4-HYP 5.5 ± 0.5. This ratio was twice as little during growth because of a relative excess of 4-HYP. In patients with acute glomerular disease (acute and subacute glomerulonephritis, lupus nephritis...) (n = 13) 3-HYP was 17.1 ± 5.8 µmol/24 h (p < 0.01 when compared with the normal) and 4-HYP 234 ± 77 µmol/24 h. The ratio between the two values was 7.3 ± 0.7 (p < 0.001). Such an increase in 3-HYP was not observed in patients with chronic glomerulonephritis (n = 24) where 3-HYP was 9.6 + 5.7 µmol/24 h and 3-HYP/4-HYP 6.0 + 1.6, neither in patients with diabetic glomerulonephritis (n = 6). In chronic interstitial nephritis (n = 8) the 3-HYP/4-HYP ratio was decreased with the exception of polykystic renal disease (PKD), where it was increased (p < 0.001). The daily urinary contents of 3-HYP and 4-HYP were slightly altered by renal insufficiency. In glomerulonephritis with nephrotic syndrome whatever the histological lesions, urinary 3-HYP did not change significantly. These preliminary results indicate that urinary 3-HYP (1) is increased when glomerulonephritis is clinically acute or subacute; (2) is increased in PKD suggesting a possible inborn error of collagen metabolism.
Protein Permeability and Immune Complex Deposition in Glomerular Capillary Walls of Rats
Authors: Nagase Mistumasa , Honda Nishio
Published: November 2008

The effect of reduced glomerular anionic charge on immune complex deposition in the glomerular basement membrane was studied in rats with Heymann nephritis. A reduction of the anionic charge was induced by lysozyme administration. The animals were divided into the following four groups: normal controls (group A), group B treated with lysozyme, group C treated with lysozyme and immunized with autologous tubular antigen, and group D immunized with the antigen. Proteinuria was marked in groups B, C and D as compared with group A, especially in group D. Development of Heymann nephritis by the tubular antigen was suppressed in group C. Stainings of anionic substances in the glomerular capillary walls by cationic probes were weakened in group B, C and D. Immune complex deposited in the subepithelial area of the capillary wall was also stained by cationic probes. The findings suggest that reduced glomerular anionic charge by polycations results in suppressed immune complex deposition in the basement membrane, partially due to increased permeation of macromolecules across the glomerular capillary walls in rats.