bluuebunny/crossref_metadata_2025 huggingface dataset:
Obligatory premarital tests for β‐thalassaemia in the Gaza Strip: evaluation and recommendations
Authors: TARAZI I. , AL NAJJAR E. , LULU N. , SIRDAH M.
Published: March 2007

β‐Thalassaemia is a major health problem in the Gaza Strip, Palestine, where 293 patients are currently treated with transfusions and chelation. In September 2000, Palestine adopted a prevention programme of obligatory premarital testing for β‐thalassaemia before the issue of a marriage certificate. From April 2003 to May 2005, 21 825 blood samples from 19 712 couples were collected and analysed. Samples (n = 2251, 10.3%) with microcytosis (mean cell volume <80 fl) and/or hypochromasia (mean cell haemoglobin <26 pg) were considered as suspicious for β‐thalassaemia and subjected to serum ferritin and HbA2 quantification. Of these samples, 25% were carriers for β‐thalassaemia while 32.4% were iron deficient. A diagnosis could not be established in 15.3% of the suspect samples. An increasing percentages of carrier couples did not go ahead with their marriage in the successive years of the programme, which was fitted to zero in the first year and reached 73.7% in the year 2005 (both partners were carriers in 19 couples, 14 decided to separate while five continued). Since implementation, there has been a reduction in the birth of children with β‐thalassaemia major. This study evaluated the 5‐year experience of the Gaza Strip in implementing the obligatory premarital testing programme for β‐thalassaemia and recommends measures that could improve it.
Propagation in an elastic wedge using the virtual source technique
Authors: Abawi Ahmad T. , Porter Michael B.
Published: March 2007

The virtual source technique, which is based on the boundary integral method, provides the means to impose boundary conditions on arbitrarily shaped boundaries by replacing them by a collection of sources whose amplitudes are determined from the boundary conditions. In this paper the virtual source technique is used to model propagation of waves in a range-dependent ocean overlying an elastic bottom with arbitrarily shaped ocean-bottom interface. The method is applied to propagation in an elastic Pekeris waveguide, an acoustic wedge, and an elastic wedge. In the case of propagation in an elastic Pekeris waveguide, the results agree very well with those obtained from the wavenumber integral technique, as they do with the solution of the parabolic equation (PE) technique in the case of propagation in an acoustic wedge. The results for propagation in an elastic wedge qualitatively agree with those obtained from an elastic PE solution.
A computational method of evaluating noncompact sound based on vortex sound theory
Authors: Takaishi T. , Miyazawa M. , Kato C.
Published: March 2007

A numerical investigation is made of the production of sound by turbulence interacting with a noncompact body. The problem is formulated in the frequency domain by extending the theory of vortex sound proposed by Howe. The anomalous “numerical” generation of sound by the sudden termination of Lighthill’s stress tensor at the outer boundary of a finite computational domain is avoided by identification of “scattered” sound sources that generate sound principally by interaction with the solid surface. It is argued that the boundary element method is the most efficient means of computing the aeroacoustic Green’s function for the problem, because it requires a minimum of CPU time, is not prone to numerical errors such as dispersion and dissipation during propagation, and the radiation condition is easily applied at the outer boundary. The method is applied to the problem of sound generation by high Reynolds number flow past a circular cylinder. The “scattered” sources are shown to be confined to the vicinity of the cylinder surface. At low frequencies the radiation has a dipole-like directivity in agreement with the compact approximation. However, the directivity is quite different at high frequencies, where our noncompact method predicts a more complicated “leaf-like” radiation pattern.
A moving zone of quiet for narrowband noise in a one-dimensional duct using virtual sensing
Authors: Petersen Cornelis D. , Zander Anthony C. , Cazzolato Ben S. , Hansen Colin H.
Published: March 2007

A frequent problem in active noise control is that the zone of quiet created at the error sensor tends to be very small. This means that the error sensor generally needs to be located close to an observer’s ear, which might not always be a convenient or feasible solution. Virtual sensing is a method that can move the zone of quiet away from the error sensor to a desired location that is spatially fixed. This method has been investigated previously, and has shown potential to improve the performance of an active noise control system. However, it is very likely that the desired location of the zone of quiet is not spatially fixed. An active noise control system incorporating a virtual sensing method thus has to be able to create a moving zone of quiet that tracks the observer’s ears. This paper presents a method for creating a moving zone of quiet based on the LMS virtual microphone technique. To illustrate the proposed method, it is implemented in an acoustic duct and narrowband control results are presented. These results show that a moving zone of quiet was effectively created inside the duct for narrowband noise.
Experiments on sound generation in corrugated pipes with flow
Authors: Kristiansen Ulf R. , Wiik Geir A.
Published: March 2007

The article reports acoustic measurements on short corrugated pipes with flow. Such pipes might generate high sound levels associated with length resonances. One of the main objectives of the study was to estimate the location of the effective sources by studying the energy flow through the pipes. It was found that a short section of corrugations will only produce sound effectively when placed at the inflow end, while for fully corrugated pipes, the sound-producing regions are located around the pressure maxima of the observed standing waves. It was further found that the net energy flow is in the upstream direction for nearly the complete length of pipe.
Elastic waves excited by a plane source on the surface of a multilayered medium
Authors: Zhang Bixing
Published: March 2007

Elastic waves excited by a plane piezoelectric source with an arbitrary shape on the surface of a multilayered medium have been studied for the first time in this paper. On the basis of Abzo-zena [Geophys. J. R. Astron. Soc. 58, 91–105 (1979)] and Menke [Geophys. J. R. Astron. Soc. 59, 315–323 (1979)], the propagator matrix for the elastic wave field in multilayered medium is extended from two- to three-dimensional (3D) space. 3D elastic wave field is investigated and the displacement-stress response for the boundary conditions is obtained. The propagation of elastic wave in multilayered media is analyzed in 3D space in the frequency domain. The P-SV and SH modes corresponding to the poles are studied. The excitation and propagation of the modes are analyzed further. It is found that the propagation velocities of the P-SV and SH modes do not depend on the propagation azimuth θ in the plane parallel to the free surface of the multilayered medium while the displacement amplitudes are strongly dependent on the azimuth θ. The directional distribution functions of the modes are independent of the medium parameters and the modes and dependent on the shape and excitation fashion of the source. Finally, as an example, the displacement fields of the P-SV and SH modes excited by a rectangle source are analyzed. The displacement representation and numerical results of the directivity distribution functions for the P-SV and SH modes are obtained.
Multipath pulse shapes in shallow water: Theory and simulation
Authors: Harrison Chris H. , Nielsen Peter L.
Published: March 2007

In shallow water propagation the steeper ray angles are weakened most by boundary losses. Regarding the sound intensity as a continuous function of angle it can be converted into a function of travel time to reveal the multipath pulse shape received from a remote source (one-way path) or a target (two-way path). The closed-form isovelocity pulse shape is extended here to the case of upward or downward refraction. The envelope of the earliest arrivals is roughly trapezoidal with a delayed peak corresponding to the slowest, near horizontal refracted paths. The tail of the pulse falls off exponentially (linearly in decibels) with a decay constant that depends only on the bottom reflection properties and water depth, irrespective of travel time, a useful property for geoacoustic inversion and for sonar design. The nontrivial analytical problem of inverting explicit functions of angle into explicit functions of time is solved by numerical interpolation. Thus exact solutions can be calculated numerically. Explicit closed-form approximations are given for one-way paths. Two-way paths are calculated by numerical convolution. Using the wave model C-SNAP in several broadband cases of interest it is demonstrated that these solutions correspond roughly to a depth average of multipath arrivals.
Hearing loss from interrupted, intermittent, and time varying Gaussian noise exposures: The applicability of the equal energy hypothesis
Authors: Qiu Wei , Davis Bob , Hamernik Roger P.
Published: March 2007

Eight groups of chinchillas (N=74) were exposed to various equivalent energy [100 or 106dB(A) sound pressure level (SPL)] noise exposure paradigms. Six groups received an interrupted, intermittent, time varying (IITV) Gaussian noise exposure that lasted 8h∕d, 5d∕week for 3 weeks. The exposures modeled an idealized workweek. At each level, three different temporal patterns of Gaussian IITV noise were used. The 100dB(A) IITV exposure had a dB range of 90–108dB SPL while the range of the 106dB(A) IITV exposure was 80–115dB SPL. Two reference groups were exposed to a uniform 100 or 106dB(A) SPL noise, 24h∕d for 5 days. Each reference group and the three corresponding IITV groups comprised a set of equivalent energy exposures. Evoked potentials were used to estimate hearing thresholds and surface preparation histology quantified sensory cell populations. All six groups exposed to the IITV noise showed threshold toughening effects of up to 40dB. All IITV exposures produced hearing and sensory cell loss that was similar to their respective equivalent energy reference group. These results indicate that for Gaussian noise the equal energy hypothesis for noise-induced hearing loss is an acceptable unifying principle.
Nearfield binaural synthesis and ambisonics
Authors: Menzies Dylan , Al-Akaidi Marwan
Published: March 2007

Ambisonic encodings can be rendered binaurally, as well as for speaker arrays. This process is developed for general high-order Ambisonic encodings of soundfields containing near as well as far sources. For sufficently near sources an error is identified, resulting from the limited field of validity of the freefield harmonic expansion. A modified expansion is derived that can render such sources correctly.
Improved precision in measurements of acoustic impedance spectra using resonance-free calibration loads and controlled error distribution
Authors: Dickens Paul , Smith John , Wolfe Joe
Published: March 2007

Resonances and/or singularities during measurement and calibration often limit the precision of acoustic impedance spectra. This paper reviews and compares several established techniques, and describes a technique that incorporates three features that considerably improve precision. The first feature is to minimize problems due to resonances by calibrating the instrument using up to three different acoustic reference impedances that do not themselves exhibit resonances. The second involves using multiple pressure transducers to reduce the effects of measurement singularities. The third involves iteratively tailoring the spectrum of the stimulus signal to control the distribution of errors across the particular measured impedance spectrum. Examples are given of the performance of the technique on simple cylindrical waveguides.
Bias due to noise in otoacoustic emission measurements
Authors: Backus Bradford C.
Published: March 2007

Measurements of otoacoustic emission (OAE) magnitude are often made at low signal/noise ratios (SNRs) where measurement noise generates bias and variability errors that have led to the misinterpretation of OAE data. To gain an understanding for these errors and their effects, a two part investigation was carried out. First, the nature of OAE measurement noise was investigated using human data from 50 stimulus-frequency OAE experiments involving medial olivocochlear reflex (MOCR) activation. The noise was found to be reasonably approximated by circular Gaussian noise. Furthermore, when bias errors were taken into account, measurement variability was not found to be affected by MOCR activation as had been previously reported. Second, to quantify the errors circular Gaussian noise produces for different methods of OAE magnitude estimation for distortion-product, stimulus-frequency, and spontaneous OAEs, simulated OAE measurements were analyzed via four different magnitude estimation methods and compared. At low SNRs (below ∼6dB), estimators involving Rice probability density functions produced less biased estimates of OAE magnitudes than conventional estimation methods, and less total rms error—particularly for spontaneous OAEs. They also enabled the calculation of probability density functions for OAE magnitudes from experimental data.
Reproducible cavitation activity in water-particle suspensions
Authors: Borkent Bram M. , Arora Manish , Ohl Claus-Dieter
Published: March 2007

The study of cavitation inception in liquids rarely yields reproducible data, unless special control is taken on the cleanliness of the experimental environment. In this paper, an experimental technique is demonstrated which allows repeatable measurements of cavitation activity in liquid-particle suspensions. In addition, the method is noninvasive: cavitation bubbles are generated using a shock-wave generator, and they are photographed using a digital camera. The cavitation activity is obtained after suitable image processing steps. From these measurements, the importance of the particle’s surface structure and its chemical composition is revealed, with polystyrene and polyamide particles generating the highest yields. Further findings are that cavitation nuclei become depleted with an increasing number of experiments, and the existence of nuclei with varying negative pressure thresholds. Finally, a decrease of the cavitation yield is achieved by prepressurization of the suspension—indicating that the cavitation nuclei are gaseous.
Interaural time difference processing of broadband and narrow-band noise by inexperienced listeners
Authors: Yost William A. , Dye Raymond H. , Sheft Stanley
Published: March 2007

Recent functional magnetic resonance imaging (fMRI) data might be interpreted as being in disagreement with existing psychophysical data regarding the laterality of broadband noise stimuli presented with large interaural time differences (ITDs). This study investigated the possibility that lateral judgments made by inexperienced listeners who did not receive feedback might be different than those reported for experienced listeners, especially when the ITD is longer than that occurring in nature, and therefore data from inexperienced listeners presented unnaturally long ITDs for the first time might be more consistent with the possible interpretation of the fMRI results. The results from this study using inexperienced listeners were not basically different from those reported in the literature based on experienced listeners, suggesting a possible difference does exist between inferences drawn from fMRI data and human psychophysical results.
Evaluation of the
metS
and
murB
Loci for Antibiotic Discovery Using Targeted Antisense RNA Expression Analysis in
Bacillus anthracis
Authors: Kedar G. C. , Brown-Driver Vickie , Reyes Daniel R. , Hilgers Mark T. , Stidham Mark A. , Shaw Karen Joy , Finn John , Haselbeck Robert J.
Published: March 2007

The biowarfare-relevant bacterial pathogen
Bacillus anthracis
contains two paralogs each of the
metS
and
murB
genes, which encode the important antibiotic target functions methionyl-tRNA synthetase and UDP-
N
-acetylenolpyruvoylglucosamine reductase, respectively. Empirical screens were conducted to detect and characterize gene fragments of each of these four genes that could cause growth reduction of
B. anthracis
when inducibly expressed from a plasmid-borne promoter. Numerous such gene fragments that were overwhelmingly in the antisense orientation were identified for the
metS1
and
murB2
alleles, while no such orientation bias was seen for the
metS2
and
murB1
alleles. Gene replacement mutagenesis was used to confirm the essentiality of the
metS1
and
murB2
alleles, and the nonessentiality of the
metS2
and
murB1
alleles, for vegetative growth. Induced transcription of RNA from
metS1
and
murB2
antisense-oriented gene fragments resulted in specific reduction of mRNA of their cognate genes. Attenuation of MetS1 enzyme expression hypersensitized
B. anthracis
cells to a MetS-specific antimicrobial compound but not to other antibiotics that affect cell wall assembly, fatty acid biosynthesis, protein translation, or DNA replication. Antisense-dependent reduction of MurB2 enzyme expression caused hypersensitivity to beta-lactam antibiotics, a synergistic response that has also been noted for the MurA-specific antibiotic fosfomycin. These experiments form the basis of mode-of-action detection assays that can be used in the discovery of novel MetS- or MurB-specific antibiotic drugs that are effective against
B. anthracis
or other gram-positive bacterial pathogens.
Enteropathogenic
Escherichia coli
-Induced Epidermal Growth Factor Receptor Activation Contributes to Physiological Alterations in Intestinal Epithelial Cells
Authors: Roxas Jennifer L. , Koutsouris Athanasia , Viswanathan V. K.
Published: March 2007

The diarrheagenic pathogen enteropathogenic
Escherichia coli
(EPEC) is responsible for significant infant mortality and morbidity, particularly in developing countries. EPEC pathogenesis relies on a type III secretion system-mediated transfer of virulence effectors into host cells. EPEC modulates host cell survival and inflammation, although the proximal signaling pathways have not been well defined. We therefore examined the effect of EPEC on the epidermal growth factor receptor (EGFR), a known upstream activator of both the prosurvival phosphoinositide 3-kinase/Akt and proinflammatory mitogen-activated protein (MAP) kinase pathways. EPEC induced the autophosphorylation of EGFR in intestinal epithelial cells within 15 min postinfection, with maximal phosphorylation being observed at 4 h. Filter-sterilized supernatants of EPEC cultures also stimulated EGFR phosphorylation, suggesting that a secreted component(s) contributes to this activity. EPEC-induced EGFR phosphorylation was blocked by the pharmacological inhibitor tyrphostin AG1478, as well as by EGFR-neutralizing antibodies. Inhibition of EGFR phosphorylation by AG1478 had no effect on bacterial adherence, actin recruitment to sites of attachment, or EPEC-induced epithelial barrier function alteration. EPEC-mediated Akt phosphorylation, however, was inhibited by both AG1478 and EGFR-neutralizing antibodies. Correspondingly, inhibition of EGFR activation increased the apoptosis/necrosis of infected epithelial cells. Inhibition of EGFR phosphorylation also curtailed EPEC-induced ERK1/2 (MAP kinase) phosphorylation and, correspondingly, the production of the proinflammatory cytokine interleukin-8 by infected epithelial cells. Our studies suggest that EGFR is a key proximal signaling molecule during EPEC pathogenesis.
Interaction ofCandida albicanswith Adherent Human Peripheral Blood Mononuclear Cells IncreasesC. albicansBiofilm Formation and Results in Differential Expression of Pro- and Anti-Inflammatory Cytokines
Authors: Chandra Jyotsna , McCormick Thomas S. , Imamura Yoshifumi , Mukherjee Pranab K. , Ghannoum Mahmoud A.
Published: March 2007

Monocytes and macrophages are the cell types most commonly associated with the innate immune response againstCandida albicansinfection. Interactions between the host immune system andCandidaorganisms have been investigated for planktonicCandidacells, but no studies have addressed these interactions in a biofilm environment. In this study, for the first time, we evaluated the ability ofC. albicansto form biofilms in the presence or absence of adherent peripheral blood mononuclear cells (PBMCs; enriched for monocytes and macrophages by adherence). Our analyses using scanning electron and confocal scanning laser microscopy showed that the presence of PBMCs enhanced the ability ofC. albicansto form biofilms and that the majority of PBMCs were localized to the basal and middle layers of the biofilm. In contrast to the interactions of PBMCs with planktonicC. albicans, where PBMCs phagocytose fungal cells, PBMCs did not appear to phagocytose fungal cells in biofilms. Furthermore, time-lapse laser microscopy revealed dynamic interactions betweenC. albicansand PBMCs in a biofilm. Additionally, we found that (i) only viable PBMCs influenceCandidabiofilm formation, (ii) cell surface components of PBMCs did not contribute to the enhancement ofC. albicansbiofilm, (iii) the biofilm-enhancing effect of PBMCs is mediated by a soluble factor released into the coculture medium of PBMCs withC. albicans, and (iv) supernatant collected from this coculture contained differential levels of pro- and anti-inflammatory cytokines. Our studies provide new insight into the interaction betweenCandidabiofilm and host immune cells and demonstrate that immunocytes may influence the ability ofC. albicansto form biofilms.
Live Attenuated
Streptococcus pneumoniae
Strains Induce Serotype-Independent Mucosal and Systemic Protection in Mice
Authors: Roche Aoife M. , King Samantha J. , Weiser Jeffrey N.
Published: March 2007

Streptococcus pneumoniae
is an important human pathogen causing both mucosal (otitis media and pneumonia) and systemic (sepsis and meningitis) diseases. Due to increasing rates of antibiotic resistance, there is an urgent need to improve prevention of pneumococcal disease. Two currently licensed vaccines have been successful in reducing pneumococcal disease, but there are limitations with their use and effectiveness. Another approach for prevention is the use of live attenuated vaccines. Here we investigate the safety and protection induced by live attenuated strains of
S. pneumoniae
containing combinations of deletions in genes encoding three of its major virulence determinants: capsular polysaccharide (
cps
), pneumolysin (
ply
), and pneumococcal surface protein A (
pspA
). Both the
cps
and
ply/pspA
mutants of a virulent type 6A isolate were significantly attenuated in a mouse model of sepsis. These attenuated strains retained the ability to colonize the upper respiratory tract. A single intranasal administration of live attenuated vaccine without adjuvant was sufficient to induce both systemic and mucosal protection from challenge with a high dose of the parent strain. Immunization with
cps
mutants demonstrated cross-protective immunity following challenge with a distantly related isolate. Serum and mucosal antibody titers were significantly increased in mice immunized with the vaccine strains, and this antibody is required for full protection, as μMT mice, which do not make functional, specific antibody, were not protected by immunization with vaccine strains. Thus, colonization by live attenuated
S. pneumoniae
is a potentially safe and less complex vaccine strategy that may offer broad protection.
ON THE WEDDERBURN PRINCIPAL THEOREM IN CONFORMAL ALGEBRAS
Authors: KOLESNIKOV PAVEL
Published: March 2007

We investigate an analogue of the Wedderburn principal theorem for associative conformal algebras with finite faithful representations. It is shown that the radical splitting property for an algebra of this kind holds if the maximal semisimple factor of this algebra is unital, but does not hold in general.
O'NAN GROUP UNIQUELY DETERMINED BY THE CENTRALIZER OF A 2-CENTRAL INVOLUTION
Authors: MICHLER GERHARD O. , PREVITALI ANDREA
Published: March 2007

In this paper we give a self-contained existence and uniqueness proof for the sporadic O'Nan group ON by showing that it is uniquely determined up to isomorphism by the centralizer H of a 2-central involution z. We establish for such a simple group G a presentation in terms of generators and defining relations and a faithful permutation representation of degree 2.624.832 with a uniquely determined stabilizer isomorphic to the small sporadic Janko group J1. We also calculate its character table by new methods and determine a system of representatives of the conjugacy classes of G.
SELFGRAVITATION IN A GENERAL-RELATIVISTIC ACCRETION OF STEADY FLUIDS
Authors: KINASIEWICZ BOGUSZ , MACH PATRYK , MALEC EDWARD
Published: March 2007

The selfgravity of an infalling gas can alter significantly the accretion of gases. In the case of spherically symmetric steady flows of polytropic perfect fluids the mass accretion rate achieves maximal value when the mass of the fluid is 1/3 of the total mass. There are two weakly accreting regimes, one over-abundant and the other poor in fluid content. The analysis within the newtonian gravity suggests that selfgravitating fluids can be unstable, in contrast to the accretion of test fluids.
Binge alcohol exposure in the second trimester attenuates fetal cerebral blood flow response to hypoxia
Authors: Mayock Dennis E. , Ness Dana , Mondares Robin L. , Gleason Christine A.
Published: March 2007

Alcohol is detrimental to the developing brain and remains the leading cause of mental retardation in developed countries. The mechanism of alcohol brain damage remains elusive. Studies of neurological problems in adults have focused on alcohol's cerebrovascular effects, because alcoholism is a major risk factor for stroke and cerebrovascular injuries. However, few studies have examined similar cerebrovascular effects of fetal alcohol exposure. We examined the effect of chronic binge alcohol exposure during the second trimester on fetal cerebrovascular and metabolic responses to hypoxia in near-term sheep and tested the hypothesis that fetal alcohol exposure would attenuate cerebrovascular dilation to hypoxia. Pregnant ewes were infused with alcohol (1.5 g/kg) or saline intravenously at 60–90 days of gestation (full term = 150 days). At 125 days of gestation, we measured fetal cerebral blood flow (CBF) and oxygen metabolism at baseline and during hypoxia. Maternal blood alcohol averaged 214 ± 5.9 mg/dl immediately after the 1.5-h infusion, with similar values throughout the month of infusion. Hypoxia resulted in a robust increase in CBF in saline-infused fetuses. However, the CBF response to hypoxia in fetuses chronically exposed to alcohol was significantly attenuated. Cerebral oxygen delivery decreased in both groups of fetuses during hypoxia but to a greater degree in the alcohol-exposed fetuses. Prenatal alcohol exposure during the second trimester attenuates cerebrovascular responses to hypoxia in the third trimester. Altered cerebrovascular reactivity might be one mechanism for alcohol-related brain damage and might set the stage for further brain injury if a hypoxic insult occurs.
Inhibition of Horse Liver Alcohol Dehydrogenase byMethyltin Compounds
Authors: Bychkov Pavel V. , Shekhovtsova Tatyana N. , Milaeva Elena R.
Published: March 2007

The study of inorganic tin (SnCl2, SnCl4) and methyltin compounds (MeSnCl3, Me2SnCI2, Me3SnCl)
effects on the enzymatic activity of alcohol dehydrogenase (ADH) in the reaction of ethanol oxidation has
been carried out. The experimental results of the study show that inorganic tin and methyltin substances
induce slight inhibition of the catalytic activity of horse liver alcohol dehydrogenase (HLADH), unable to be
improved during pre‐incubation with the enzyme. The conditions for carrying out the kinetic investigation of
the mentioned phenomenon were optimized and as it turned out the mechanism of methyltin trichloride
action, as the most effective methyltin inhibitor, is more complex than the proposed interaction of the metal
atom with SH‐groups of the enzyme protein. It was demonstrated that the tin compounds act in the same
manner as methylmercury compounds and might serve as oxidative agents towards the co‐enzyme NADH.
Kinetic data on MeSnCl3 were calculated. Data acquired on NAD‐dependent ADH from horse liver and those
regarding NAD‐dependent LDH from sturgeon liver were compared.
Chances and Limits of the Coordination Chemistry withBis(benzene‐l,2‐dithiolato) Ligands
Authors: Seidel Wolfram W. , Hahn F. Ekkehardt
Published: March 2007

The incorporation of benzene‐l,2‐dithiolato building blocks into supramolecular coordination assemblies
is the main objective of the investigations described here. Special interest is directed towards dinuclear
complexes with bis(benzene‐l,2‐dithiolato) ligands, which might be able to form helical structures.
Bis(benzene‐l,2‐dithiolato) ligands are accessible by ortho‐functionalization and subsequent linkage of two
benzene‐l,2‐dithiol units. The preparation of well defined complexes of titanium, cobalt and nickel with
bis(benzene‐l,2‐dithiolato) ligands requires strictly thermodynamic equilibration conditions. In that case the
size and shape of the ligand backbone determine if dinuclear double‐stranded or mononuclear chelate
complexes are obtained. The dinuclear double‐stranded complexes with Ni(II) and Ni(III) are characterized
by a coplanar non‐helical arrangement of the square‐planar bis(benzene‐l,2‐dithiolato)nickelate moieties.
The complete structural characterization of the series (n = 0, 1, 2) for molybdenum and
tungsten indicates an interesting coordination chemistry of dinuclear triple‐stranded complexes.
Impact of Prosthesis-Patient Mismatch on Survival After Mitral Valve Replacement
Authors: Magne Julien , Mathieu Patrick , Dumesnil Jean G. , Tanné David , Dagenais François , Doyle Daniel , Pibarot Philippe
Published: March 2007

Background—

We recently reported that valve prosthesis-patient mismatch (PPM) is associated with persisting pulmonary hypertension after mitral valve replacement. Thus, the objective of this study was to evaluate the impact of PPM on mortality in patients undergoing mitral valve replacement.

Methods and Results—

The indexed valve effective orifice area was estimated for each type and size of prosthesis being implanted in 929 consecutive patients and used to define PPM as not clinically significant if >1.2 cm
2
/m
2
, as moderate if >0.9 and ≤1.2 cm
2
/m
2
, and as severe if ≤0.9 cm
2
/m
2
. Moderate PPM was present in 69% of patients; severe PPM was seen in 9%. For patients with severe PPM, 6-year survival (74±5%) and 12-year survival (63±7%) were significantly less than for patients with moderate PPM (84±1% and 76±2%;
P
=0.027) or nonsignificant PPM (90±2% and 82±4%;
P
=0.002). On multivariate analysis, severe PPM was associated with higher mortality (hazard ratio, 3.2; 95% confidence interval, 1.5 to 6.8;
P
=0.003).

Conclusions—

Severe PPM is an independent predictor of mortality after mitral valve replacement. As opposed to other independent risk factors, PPM may be avoided or its severity may be reduced with the use of a prospective strategy at the time of operation. For patients identified as being at risk for severe PPM, every effort should be made to implant a prosthesis with a larger effective orifice area.
Adjustable, Physiological Ventricular Restraint Improves Left Ventricular Mechanics and Reduces Dilatation in an Ovine Model of Chronic Heart Failure
Authors: Ghanta Ravi K. , Rangaraj Aravind , Umakanthan Ramanan , Lee Lawrence , Laurence Rita G. , Fox John A. , Bolman R. Morton , Cohn Lawrence H. , Chen Frederick Y.
Published: March 2007

Background—

Ventricular restraint is a nontransplantation surgical treatment for heart failure. The effect of varying restraint level on left ventricular (LV) mechanics and remodeling is not known. We hypothesized that restraint level may affect therapy efficacy.

Methods and Results—

We studied the immediate effect of varying restraint levels in an ovine heart failure model. We then studied the long-term effect of restraint applied over a 2-month period. Restraint level was quantified by use of fluid-filled epicardial balloons placed around the ventricles and measurement of balloon luminal pressure at end diastole. At 4 different restraint levels (0, 3, 5, and 8 mm Hg), transmural myocardial pressure (P
tm
) and indices of myocardial oxygen consumption (MV̇
o
2
) were determined in control (n=5) and ovine heart failure (n=5). Ventricular restraint therapy decreased P
tm
and MV̇
o
2
, and improved mechanical efficiency. An optimal physiological restraint level of 3 mm Hg was identified to maximize improvement without an adverse affect on systemic hemodynamics. At this optimal level, end-diastolic P
tm
and MV̇
o
2
indices decreased by 27% and 20%, respectively. The serial longitudinal effects of optimized ventricular restraint were then evaluated in ovine heart failure with (n=3) and without (n=3) restraint over 2 months. Optimized ventricular restraint prevented and reversed pathological LV dilatation (130±22 mL to 91±18 mL) and improved LV ejection fraction (27±3% to 43±5%). Measured restraint level decreased over time as the LV became smaller, and reverse remodeling slowed.

Conclusions—

Ventricular restraint level affects the degree of decrease in P
tm
, the degree of decrease in MV̇
o
2
, and the rate of LV reverse remodeling. Periodic physiological adjustments of restraint level may be required for optimal restraint therapy efficacy.
Revisiting the Possible Links between the Quasi-Biennial Oscillation and the Indian Summer Monsoon Using NCEP R-2 and CMAP Fields
Authors: Claud Chantal , Terray Pascal
Published: March 2007

In the past the stratospheric quasi-biennial oscillation (QBO) has sometimes been proposed to explain the tendency for the Indian summer monsoon (ISM) to alternate between strong and weak years. In this study, NCEP Reanalysis-2 (R-2) and Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) fields are statistically analyzed to assess the relationship between equatorial zonal winds in the stratosphere and ISM. In a first step, it is shown that zonal winds at 15 hPa during the preceding winter (January–February) are the best stratospheric predictor of the summer rainfall over the Indian subcontinent as a whole. This relationship mainly holds for August and September, or the late ISM. Surprisingly, the QBO pattern is not significantly associated with the rainfall variability during June–July or the early ISM. CMAP and NCEP R-2 fields corroborate these findings and show that westerly QBO years are associated with a deepening of the monsoon trough over the Gangetic plains and decreased convective activity in the eastern equatorial Indian region. However, further statistical analysis shows that the QBO–ISM link is complex since a westerly QBO phase at 15 hPa in boreal winter leads to a weaker monsoon surface circulation with, in particular, a weakening of the Somali jet at the beginning of the monsoon, but a much stronger circulation in September. At that time, the Tibetan high is reinforced, the tropical easterly jet at 200 hPa is stronger over India, and the local reversed Hadley circulation is also strengthened north of the equator. The mechanisms by which the QBO may affect ISM have been explored through, in particular, correlations between stratospheric winds and tropopause temperature and pressure fields. The results provide support for an out-of-phase behavior of convective activity between the Indian subcontinent and the equatorial Indian Ocean induced by the QBO phase, especially during the late ISM. During a westerly QBO phase, convective activity is, in September, enhanced over India, which brings higher precipitation, compared to the east phase. This work also suggests that the winter QBO at 15 hPa could have some skill in foreshadowing the late ISM.
Idealized Hot Spot Experiments with a General Circulation Model
Authors: Maloney Eric D. , Sobel Adam H.
Published: March 2007

Idealized experiments are conducted using a GCM coupled to a 20-m slab ocean model to examine the short-term response to an initial localized positive equatorial SST anomaly, or “hot spot.” A hot spot is imposed upon an aquaplanet with globally uniform 28°C SST, insolation, and trace gas concentrations designed to mimic tropical warm pool conditions. No boundary condition or external parameter other than the Coriolis parameter varies with latitude. A 15-member ensemble is initiated using random atmospheric initial conditions. A 2°C equatorial warm anomaly is switched on, along with ocean coupling (day 0).

Enhanced deep convection rapidly develops near the hot spot, forcing an anomalous large-scale circulation that resembles the linear response of a dry atmosphere to a localized heating, as in the Gill model. Enhanced convection, the anomalous large-scale circulation, and enhanced wind speed peak in amplitude at about day 15. Enhanced latent heat fluxes driven primarily by an increase in vector mean wind damp the anomalous heat content of the ocean near the hot spot before day 20. Between day 20 and day 50, suppressed latent heat fluxes due to suppressed synoptic eddy variance cause a warming of the remote Tropics in regions of anomalous low-level easterly flow. This wind-driven evaporative atmosphere–ocean exchange results in a 60–70-day oscillation in tropical mean oceanic heat content, accompanied by a compensating out-of-phase oscillation in vertically integrated atmospheric moist static energy. Beyond day 70 of the simulation, positive SST anomalies are found across much of the tropical belt. These slowly decay toward the 28°C background state.
‘Cultural diversity’ at work: ‘National culture’ as a discourse organizing an international project group
Authors: Barinaga Ester
Published: March 2007

Research to date concurs in maintaining that performance of nationally homogeneous workgroups differs if compared to heterogeneous ones. Yet, results are mixed on the relationship between cultural diversity and workgroup outcomes. The article argues that cultural differences are given explanatory authority, cultural diversity acquiring a positivist status, and group members being treated as ‘dopes of their culture’. An alternative approach is to conceive ‘cultural diversity’ and ‘national culture’ as discursive resources used by group members in everyday group life. The author followed an international project group for over 17 months,observing how group members discussed and made sense of what went on. Findings suggest that the way members in international project groups use the ‘national/cultural’ discourse plays a crucial role in the organization of the project. More specifically, results demonstrate that group members shaped and developed their international project in important ways by using the discourses on ‘national culture’ and ‘cultural diversity’ to excuse confusion and misunderstanding, to position themselves vis-à-vis the group, to justify decisions and to give the group a raison d'être. Implications are drawn concerning the need for researchers to acknowledge actors' space for choice in group-life.
A critique of transformational leadership: Moral, professional and contingent dimensions of leadership within public services organizations
Authors: Currie Graeme , Lockett Andy
Published: March 2007

Our study of secondary schools in England illustrates the ineffective implementation of transformational leadership within public service organizations by policy-makers. First, a rather narrow, managerialist variant of transformational leadership is promoted, which is resisted by school teachers and principals. Second, associated with this, policy does not take account of the institutional context within which public services organizations operate. Third, policy-makers, rather than leaders transform the context within which leadership takes place and any leadership discretion is constrained by central government audit. Instead, moral, professional and contingent approaches to leadership are enacted at the local level with individualized, rather than dispersed leadership, as a consequence of regulatory and normative pressures.
Confabulations in Episodic Memory Are Associated With Delusions in Alzheimer’s Disease
Authors: Lee Eunjoo , Meguro Kenichi , Hashimoto Ryusaku , Meguro Mitsue , Ishii Hiroshi , Yamaguchi Satoshi , Mori Etsuro
Published: March 2007

Although confabulations and delusions are observed in Alzheimer’s disease, the relationship between the 2 has not been fully investigated. This study involved 50 patients with Alzheimer’s disease and 10 healthy participants. After the patients were divided into delusional and nondelusional groups, confabulations and cognitive function were assessed. No confabulations appeared in the healthy participants, and only patients with Alzheimer’s disease showed confabulations. The delusional group produced more confabulations on episodic subjects than on semantic subjects. There was a correlation between cognitive impairment and confabulations in semantic memory. These findings suggest that different mechanisms are involved in confabulations between semantic and episodic memories.
Effect of Divided Attention on Gait in Subjects With and Without Cognitive Impairment
Authors: Pettersson Anna F. , Olsson Elisabeth , Wahlund Lars-Olof
Published: March 2007

The aim of this study was to investigate the influence of cognition on motor function using 2 simple everyday tasks, talking and walking, in younger subjects with Alzheimer’s disease and mild cognitive impairment. A second aim was to evaluate reliability for the dual-task test Talking While Walking. Walking speed during single and dual task and time change between single and dual task were compared between groups. The test procedure was repeated after 1 week. Subjects with AD had lower walking speed and greater time change between single and dual task compared with healthy controls. Reliability for Talking While Walking was very good. The results show that motor function in combination with a cognitive task, as well as motor function alone, influences subjects with Alzheimer’s disease in a negative way and that decreased walking speed during single- and dual-task performance may be an early symptom in Alzheimer’s disease.
Stable isotope variations in stalagmites from northwestern Sweden document climate and environmental changes during the early Holocene
Authors: Sundqvist H. S. , Holmgren K. , Lauritzen S.-E.
Published: March 2007

This paper presents two early Holocene (9.6-5.9 ka BP) high-resolution stable isotope records of stalagmites from two caves in northwestern Sweden (Korallgrottan and Labyrintgrottan). Close similarities between the Swedish records and a previously presented Norwegian stalagmite oxygen isotope record emphasize the potential of Scandinavian stalagmites to provide high-resolution regional palaeoclimatic information. The stable oxygen isotope records are interpreted to reflect the temperature evolution during the early Holocene with a gradual warming from c. 9.6 ka BP, interrupted by cooler conditions at 8.5-8.0 ka BP. The results indicate that the cooler conditions were driven by two to three abrupt cold events rather than one ‘8.2 event’ only. Except for these cold events the stalagmite oxygen isotope records show that temperatures in northwestern Sweden were warmer than today between 9.6 and 5.9 ka BP and that during this period the interval between 7.8 and 5.9 ka BP seems to have been the warmest. The high-amplitude changes in the stable carbon isotope record of Labyrintgrottan are proposed to reflect changes in local vegetation. The area above Labyrintgrottan was most likely covered by much denser vegetation than today at the time of stalagmite growth (9.5-7.5 ka BP) and was -unlike today -probably situated below the local tree limit between 9.0 and 8.0 ka BP.
Dating of the Narssarssuaq stade in southern Greenland
Authors: Bennike Ole , Sparrenbom Charlotte J.
Published: March 2007

Following the Holocene thermal maximum, the Greenland ice sheet began to expand, and many local glaciers formed. The maximum extent of most outlet glaciers from the Inland Ice was reached around 100 to 200 years ago. However, some exceptions have been recorded. In southern Greenland, the Neoglacial Narssarssuaq stade marks an older re-advance that exceeded the historical advance. The dating of the Narssarssuaq stade has been much debated. Here we present new radiocarbon dates from a sediment core collected from a small lake within the moraines formed during this stade. A minimum age for the Narssarssuaq stade of around 1200 yr BP is suggested from the dates.
Sensible Knowledge and Practice-based Learning
Authors: Strati Antonio
Published: March 2007

The article shows that there is a close connection between knowing and learning in practice and sensible knowledge. It does so by referring to field research conducted in a variety of workplaces: a sawmill, a roofing firm and a secretarial office. The concluding remarks argue for the re-construction of organizational discourse through aesthetic understanding, because this is an approach which brings out the ‘don't-know-what’ characteristic of a large part of practical experience in organizations.
Leaders as Lead Learners
Authors: James Kim Turnbull , Mann Jasbir , Creasy Jane
Published: March 2007

Distributed leadership is increasingly desired in traditionally top-down organizations. This article bridges a gap between theory about distributed leadership, which addresses not only how leadership is exercised through collaborative practices, but also where and by whomit is undertaken. The idea of distributed leadership highlights the need for new and congruent development methodologies, without which calls for distributed leadership will flounder. Distributed leadership involves systemic change and cannot be achieved through individualized leadership development alone; people throughout the organization need to revise ideas about leadership, including top leaders. Top leaders need a safe learning environment that mirrors this new mode of working, offering opportunities for re-examining leadership and learning. Through an exploration of the psychological challenges of distributed leadership, a learning design that supports learning for distributing leadership is proposed. This incorporates attention to system dynamics and a collaborative learning methodology. It is illustrated by an example from school leadership.
Evaluating Policy Integration
Authors: Mickwitz Per , Kivimaa Paula
Published: March 2007

The integration of certain policy objectives into other policy sectors – i.e. policy integration of such issues as gender, regional development, employment and environmental protection – is frequently requested in order to improve public policy. The article discusses the importance of evaluating policy integration as well as the perspective that such evaluations should extend to the outputs and outcomes of policies. Two examples of evaluating policy integration are provided: the integration of environmental concerns into technology policy and the integration of innovation objectives into environmental policy. The findings show that the integration of environmental concerns into technology policies could be increased, especially with respect to promoting technologies that do not have explicit environmental intentions. Similarly, innovation objectives could be further integrated into environmental policies. Evaluations of policy principles, such as policy integration, are important for policy development.