bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advances in laser-based isotope ratio measurements: selected applications
Authors: Kerstel E. , Gianfrani L. 
Published: August 2008

AbstractSmall molecules exhibit characteristic ro-vibrational transitions in the near- and mid-infrared spectral regions, which are strongly influenced by isotopic substitution. This gift of nature has made it possible to use laser spectroscopy for the accurate analysis of the isotopic composition of gaseous samples. Nowadays, laser spectroscopy is clearly recognized as a valid alternative to isotope ratio mass spectrometry. Laser-based instruments are leaving the research laboratory stage and are being used by a growing number of isotope researchers for significant advances in their own field of research. In this review article, we discuss the current status and new frontiers of research on high-sensitivity and high-precision laser spectroscopy for isotope ratio analyses. Although many of our comments will be generally applicable to laser isotope ratio analyses in molecules of environmental importance, this paper concerns itself primarily with water and carbon dioxide, two molecules that were studied extensively in our respective laboratories. A complete coverage of the field is practically not feasible in the space constraints of this issue, and in any case doomed to fail, considering the large body of work that has appeared ever since the review by Kerstel in 2004 (Handbook of Stable Isotope Analytical Techniques, Chapt. 34, pp. 759–787).
The truth of treating patients with phenylketonuria after childhood: The need for a new guideline
Authors: van Spronsen F. J. , Burgard P. 
Published: August 2008

SummaryIn recent years, an increasing number of national guidelines on the treatment of phenylketonuria (PKU) have emerged. Most of these guidelines are dedicated to the care of children, while less attention is paid to the care of adults, although all guidelines underline the importance of diet for life. This review aims to summarize issues that need to be addressed within a guideline on the treatment of PKU, especially when care for patients beyond childhood is concerned. In this respect, it is of importance that adult patients, both willing and unwilling to be treated, need a guideline for care and follow‐up. In PKU there is certainly a need for an improved unified guideline, especially after childhood, although many of the considerations in this article also apply to recommendations for treatment of children. Such a guideline will be a tool to improve treatment in PKU patients but should also include recommendations for collecting data for clinical and research purposes. Guideline development should also focus on nutritional, neuropsychological and psychosocial issues and not only on target plasma phenylalanine concentrations. In addition, guidelines must address not only what has to be done but also how it can be done, thereby improving concordance with the recommendations for treatment and management.
A Simple Method to Synthesize Cadmium Hydroxide Nanobelts
Authors: Zhang DE , Pan XD , Zhu H , Li SZ , Xu GY , Zhang XB , Ying AL , Tong ZW 
Published: August 2008

Abstract
Cd(OH)2nanobelts have been synthesized in high yield by a convenient polyol method for the first time. XRD, XPS, FESEM, and TEM were used to characterize the product, which revealed that the product consisted of belt-like crystals about 40 nm in thickness and length up to several hundreds of micrometers. Studies found that the viscosity of the solvent has important influence on the morphology of the final products. The optical absorption spectrum indicates that the Cd(OH)2nanobelts have a direct band gap of 4.45 eV.
Crystallization Behavior of Fatty Acid Methyl Esters
Authors: Dunn Robert O. 
Published: August 2008

AbstractBiodiesel from most agricultural feedstocks has flow properties that are prone to startup and operability problems during cold weather. Biodiesel from soybean oil is generally a mixture of long‐chain fatty acid alkyl esters composed of 0.15–0.20 mass fraction saturated esters (melting point [MP] ≫ 0 °C) mixed with unsaturated esters (MP < 0 °C). This work investigates the crystallization properties of two saturated fatty acid methyl esters (FAME) commonly found in biodiesel from soybean oil. Differential scanning calorimetry (DSC) heating and cooling scans of methyl palmitate (MeC16), methyl stearate (MeC18) and methyl oleate (MeC18:1) in pure form were analyzed. Crystallization behavior in ternary FAME mixtures was inferred by the application of thermodynamic models based on ideal solution and freezing‐point depression theories. Activity coefficients for MeC16 and MeC18 in MeC18:1 solvent were determined by analyzing DSC cooling curves for binary FAME mixtures. Eutectic points were predicted by both models. Crystallization onset temperatures inferred from freezing point depression theory were more accurate than those for ideal solutions with respect to a direct DSC cooling curve analysis of corresponding ternary mixtures. This work shows that the crystallization onset temperature (cloud point) of biodiesel may be predicted by freezing‐point depression theory if the activity coefficients of the component FAME are known.
ACCEPTABILITY OF FORAGE LEGUMES FOR IMPROVED FALLOWS – FIRST EXPERIENCES OF AGRO-PASTORALISTS IN SUBHUMID SOUTHWEST NIGERIA
Authors: Muhr L. , Tarawali S. A. , Peters M. , Schultze-Kraft R. 
Published: August 2008

In the process of developing an improved fallow system based on forage legumes, the potential interest of crop-livestock farmers in enhancing soil fertility restoration and dry-season feed supply was assessed during a socio-economic study on 11 farms of settled agro-pastoralists in the subhumid zone of West Africa. Simultaneously, eight farmers in the group participated in simple and largely farmer-managed on-farm experiments testing the establishment of selected forage legumes on fallow land. In addition to agronomic parameters, the participatory approach included an evaluation of the technology by farmers both during farm visits and field days.With cropping and dry-season feeding strategies increasingly being limited by land availability, the agronomic performance of some of the tested legume species, in particular Stylosanthes guianensis, promised substantial productivity gains once they could be integrated into the traditional fallow system. The major concerns of the farmers were animal health and labour supply for cropping activities, rather than soil fertility and feed constraints. The need for initial weed control within most of the legume species, therefore, limited their acceptability by farmers at this early stage of innovation testing. Nevertheless, farmers' interest grew remarkably in the course of the study. Options for the selection of appropriate species and management practices, which aimed at facilitating the establishment of legumes on fallow land, are discussed as a means of enhancing further adoption of the innovation.
SHORT DURATION CHICKPEA TO REPLACE FALLOW AFTER AMAN RICE: THE ROLE OF ON-FARM SEED PRIMING IN THE HIGH BARIND TRACT OF BANGLADESH
Authors: Musa A. M. , Harris D. , Johansen C. , Kumar J. 
Published: August 2008

Chickpea (Cicer arietinum) is a promising post-wet-season crop to follow rainfed rice (Oryza sativa) in the High Barind Tract of northwestern Bangladesh. Yields in farmers' fields, however, remain low (<1 t ha−1) primarily due to such factors as poor crop establishment, late sowing, and terminal drought and heat stress. Having been shown to improve plant stand and yield of chickpea in other environments, seed priming – soaking the seed overnight before surface drying and sowing the next day – was tested for its efficacy under Barind conditions.In the 1998–99 season, 30 trials grown entirely on residual soil moisture were conducted in farmers' fields. A statistically significant mean yield response to priming of 47% was obtained. In 1999–2000, 105 on-farm trials and 15 demonstrations comparing presence and absence of priming were conducted. The crop received rain during this growing season. In a randomly chosen subset of 35 trials, scientists recorded a mean yield increase due to priming of 20%; it was 22% (from 1.02 to 1.25 t ha−1) in the remaining 64 trials (6 of the 105 trials were abandoned) where farmers recorded yields. Using a different variety, the mean yield response to priming in 15 demonstrations was 17% (from 1.25 to 1.46 t ha−1).The priming response was attributed mainly to rapid seedling establishment, with higher plant stand and earlier crop maturity allowing escape from end-of-season stresses. Priming also reduced the incidence of stem and root diseases, and increased nodulation by native rhizobia. This simple technology can substantially increase chickpea yields to remunerative levels for the resource-poor farmers in this difficult environment. Further, it is suggested that this technology can act as a catalyst for the introduction of further technologies that will permit reliable and profitable cultivation of post-rainy-season crops and thus improve the livelihoods of the rural population.
Global Labor History and “the Modern World-System”: Thoughts at the Twenty-Fifth Anniversary of the Fernand Braudel Center
Authors: van der Linden Marcel 
Published: August 2008

I regard the work of the past 20 years and of some years to come as the work of
clearing the underbrush, so that we may build a more useful framework for social
science.Immanuel Wallerstein (1996)In September 1976, the Fernand Braudel Center for the Study of Economies,
Historical Systems, and Civilizations opened its doors at the State University
of New York - Binghamton. The new institution made a flying start. After
three months it presented its “Proposed Research Programs” in a substantial
booklet. In the summer of 1977, the first issue of its journal, Review, came
out. That same year, a section on the “Political Economy of World-Systems”
(PEWS), inspired by the Braudel Center, was established within the
American Sociological Association. The PEWS section has held annual
conferences and published their proceedings ever since. Since 1979, the
Center, together with the Maison des sciences de l'homme of Paris, has
sponsored a book series called “Studies in Modern Capitalism”, published by
Cambridge University Press.
Propagation of unsteady disturbances in a slowly varying duct with mean swirling flow
Authors: COOPER A. J. , PEAKE N. 
Published: August 2008

The propagation of unsteady disturbances in a slowly varying cylindrical duct carrying
mean swirling flow is described. A consistent multiple-scales solution for the mean
flow and disturbance is derived, and the effect of finite-impedance boundaries on the
propagation of disturbances in mean swirling flow is also addressed.Two degrees of mean swirl are considered: first the case when the swirl velocity is
of the same order as the axial velocity, which is applicable to turbomachinery flow
behind a rotor stage; secondly a small swirl approximation, where the swirl velocity
is of the same order as the axial slope of the duct walls, which is relevant to the flow
downstream of the stator in a turbofan engine duct.The presence of mean vorticity couples the acoustic and vorticity equations and the
associated eigenvalue problem is not self-adjoint as it is for irrotational mean flow.
In order to obtain a secularity condition, which determines the amplitude variation
along the duct, an adjoint solution for the coupled system of equations is derived.
The solution breaks down at a turning point where a mode changes from cut on to
cut off. Analysis in this region shows that the amplitude here is governed by a form
of Airy's equation, and that the effect of swirl is to introduce a small shift in the
location of the turning point. The reflection coefficient at this corrected turning point
is shown to be exp (iπ/2).The evolution of axial wavenumbers and cross-sectionally averaged amplitudes
along the duct are calculated and comparisons made between the cases of zero mean
swirl, small mean swirl and O(1) mean swirl. In a hard-walled duct it is found that
small mean swirl only affects the phase of the amplitude, but O(1) mean swirl produces
a much larger amplitude variation along the duct compared with a non-swirling mean
flow. In a duct with finite-impedance walls, mean swirl has a large damping effect
when the modes are co-rotating with the swirl. If the modes are counter-rotating then
an upstream-propagating mode can be amplified compared to the no-swirl case, but
a downstream-propagating mode remains more damped.
Theory of the Eulerian tail in the spectra of atmospheric and oceanic internal gravity waves
Authors: HINES COLIN O. 
Published: August 2008

Observed atmospheric and oceanic internal wave spectra, when analysed in an
Eulerian frame of reference, exhibit a large-wavenumber ‘tail’. In one-dimensional
vertical-wavenumber (k3) spectra, it is typically proportional to |k3|−3.In 1989, K. R. Allen and R. I. Joseph showed that a large-wavenumber tail was to
be anticipated as a consequence of Eulerian nonlinearity, and they derived relations
for the coefficients of both horizontal and vertical spectra of the form |k|−3. The coefficients were obtained only for the wave-induced vertical-displacement spectra,
and only for an input spectrum having a certain ‘canonical’ frequency variation
derived on other grounds.The present work builds on that of Allen & Joseph. It is more general in some
respects, more limited in others. It provides a more transparent form of analysis,
it treats a broad class of wave variables, and it does so for input (Lagrangian)
spectra that can be chosen by the user, free from any constraint to canonical or
other restricted forms. It provides relations whereby the full Eulerian spectrum may
be determined numerically, once the input spectrum has been chosen, and it provides
analytic forms applicable at large wavenumbers for horizontally isotropic spectra.
The derived one-dimensional vertical-wavenumber spectra are discussed in relation
to observations.Certain shortcomings in the development, both as given by Allen & Joseph and as
found here, are identified and discussed.
Vortex-induced vibrations of a cylinder with tripping wires
Authors: HOVER F. S. , TVEDT H. , TRIANTAFYLLOU M. S. 
Published: August 2008

Thin wires are attached on the outer surface and parallel to the axis of a smooth
circular cylinder in a steady cross-stream, modelling the effect of protrusions and
attachments. The impact of the wires on wake properties, and vortex-induced loads
and vibration are studied at Reynolds numbers up to 4.6
× 104, with 3.0 × 104 as
a focus point. For a stationary cylinder, wires cause significant reductions in drag
and lift coefficients, as well as an increase in the Strouhal number to a value around
0.25–0.27. For a cylinder forced to oscillate harmonically, the main observed wire
effects are: (a) an earlier onset of frequency lock-in, when compared with the smooth
cylinder case; (b) at moderate amplitude/cylinder diameter (A/D) ratios (0.2 and 0.5),
changes in the phase of wake velocity and of lift with respect to motion are translated
to higher forcing frequencies, and (c) at A/D = 1.0, no excitation region exists; the
lift force is always dissipative.The flow-induced response of a flexibly mounted cylinder with attached wires is
significantly altered as well, even far away from lock-in. Parameterizing the response
using nominal reduced velocity Vrn = U/fnD, we found that frequency lock-in occurs
and lift phase angles change through 180° at Vrn
[thkap ] 4.9; anemometry in the wake
confirms that a mode transition accompanies this premature lock-in. A plateau
of constant response is established in the range Vrn = 5.1–6.0, reducing the peak
amplitude moderately, and then vibrations are drastically reduced or eliminated
above Vrn = 6.0. The vortex-induced vibration response of the cylinder with wires is
extremely sensitive to angular bias near the critical value of Vrn = 6.0, and moderately
so in the regime of suppressed vibration.
Some observations of the effects of
micro-organisms growing on the bed of an open
channel on the turbulence properties
Authors: NIKORA V. I. , GORING D. G. , BIGGS B. J. F. 
Published: August 2008

In this paper we report the results of an experimental study of periphyton–flow
interactions conducted in a specially designed outdoor hydraulic flume. ‘Periphyton’
is a collective term for the micro-organisms which grow on stream beds, and includes
algae, bacteria, and fungi, with algae usually the dominant and most conspicuous
component. The main goals of the study are to identify potential effects of periphyton–flow interactions as
well as the potential mechanisms of mass transfer in the near-bed
region, which could influence periphyton growth and losses. The main results of the
study may be summarized as follows.A linear velocity distribution in the interfacial sublayer (i.e. below the roughness
tops), and a logarithmic distribution above the roughness tops appeared to be reasonable
approximations for both flow types, with and without periphyton on the
bed. However, the appearance of periphyton on a rough bed shifts the origin of the
bed upwards, increases the roughness length zo by 16–21%, and reduces the ratio of
the mean velocity at the level of roughness tops to the shear velocity by
≈30%. In general, below the roughness tops the periphyton suppresses the mean velocities, the
turbulent stresses, turbulence intensities, and vertical turbulent fluxes of the turbulent
energy and turbulent shear stresses.It was found that in flows without periphyton large-scale eddies successfully penetrate
the interfacial sublayer. However, tufts of periphyton on the tops of the
roughness elements significantly weaken the penetration processes leading to spatial
de-correlation in the velocity field within the interfacial sublayer. The appearance of
periphyton on the bed does not change appreciably the velocity spectra above the
roughness tops but reduces the total spectral energy and generates a wide spectral
peak in the interfacial sublayer. Most probably, this peak is formed by penetration
of sweep events into the interfacial sublayer, ‘filtered’ by the periphyton tufts. Thus,
sweep events may be the main mechanism responsible for the delivery of nutrients
from the outer region to the biologically active interfacial sublayer. The potential
effects of flow properties on the periphyton community are also discussed.
Density-driven instabilities of miscible fluids in a
Hele-Shaw cell: linear stability analysis of the
three-dimensional Stokes equations
Authors: GRAF F. , MEIBURG E. , HÄRTEL C. 
Published: August 2008

We consider the situation of a heavier fluid placed above a lighter one in a vertically
arranged Hele-Shaw cell. The two fluids are miscible in all proportions. For this
configuration, experiments and nonlinear simulations recently reported by Fernandez
et al. (2002) indicate the existence of a low-Rayleigh-number (Ra) ‘Hele-Shaw’ instability
mode, along with a high-Ra ‘gap’ mode whose dominant wavelength is on
the order of five times the gap width. These findings are in disagreement with linear
stability results based on the gap-averaged Hele-Shaw approach, which predict much
smaller wavelengths. Similar observations have been made for immiscible flows as
well (Maxworthy 1989).In order to resolve the above discrepancy, we perform a linear stability analysis
based on the full three-dimensional Stokes equations. A generalized eigenvalue problem
is formulated, whose numerical solution yields both the growth rate and the
two-dimensional eigenfunctions in the cross-gap plane as functions of the spanwise
wavenumber, an ‘interface’ thickness parameter, and Ra. For large Ra, the dispersion
relations confirm that the optimally amplified wavelength is about five times the gap
width, with the exact value depending on the interface thickness. The corresponding
growth rate is in very good agreement with the experimental data as well. The eigenfunctions
indicate that the predominant fluid motion occurs within the plane of the
Hele-Shaw cell. However, for large Ra purely two-dimensional modes are also amplified,
for which there is no motion in the spanwise direction. Scaling laws are provided
for the dependence of the maximum growth rate, the corresponding wavenumber, and
the cutoff wavenumber on Ra and the interface thickness. Furthermore, the present
results are compared both with experimental data, as well as with linear stability
results obtained from the Hele-Shaw equations and a modified Brinkman equation.
A study of the flow-field evolution and mixing
in a planar turbulent jet using direct
numerical simulation
Authors: STANLEY S. A. , SARKAR S. , MELLADO J. P. 
Published: August 2008

Turbulent plane jets are prototypical free shear flows of practical interest in propulsion,
combustion and environmental flows. While considerable experimental research has
been performed on planar jets, very few computational studies exist. To the authors'
knowledge, this is the first computational study of spatially evolving three-dimensional
planar turbulent jets utilizing direct numerical simulation. Jet growth rates as well
as the mean velocity, mean scalar and Reynolds stress profiles compare well with
experimental data. Coherency spectra, vorticity visualization and autospectra are
obtained to identify inferred structures. The development of the initial shear layer
instability, as well as the evolution into the jet column mode downstream is captured
well.The large- and small-scale anisotropies in the jet are discussed in detail. It is
shown that, while the large scales in the flow field adjust slowly to variations in
the local mean velocity gradients, the small scales adjust rapidly. Near the centreline
of the jet, the small scales of turbulence are more isotropic. The mixing process
is studied through analysis of the probability density functions of a passive scalar.
Immediately after the rollup of vortical structures in the shear layers, the mixing
process is dominated by large-scale engulfing of fluid. However, small-scale mixing
dominates further downstream in the turbulent core of the self-similar region of the
jet and a change from non-marching to marching PDFs is observed. Near the jet
edges, the effects of large-scale engulfing of coflow fluid continue to influence the
PDFs and non-marching type behaviour is observed.