bluuebunny/crossref_metadata_2025 huggingface dataset:
An examination of cetacean brain structure with a novel hypothesis correlating thermogenesis to the evolution of a big brain
Authors: Manger Paul R.
Published: March 2006

This review examines aspects of cetacean brain structure related to behaviour and evolution. Major considerations include cetacean brain‐body allometry, structure of the cerebral cortex, the hippocampal formation, specialisations of the cetacean brain related to vocalisations and sleep phenomenology, paleoneurology, and brain‐body allometry during cetacean evolution. These data are assimilated to demonstrate that there is no neural basis for the often‐asserted high intellectual abilities of cetaceans. Despite this, the cetaceans do have volume‐trically large brains. A novel hypothesis regarding the evolution of large brain size in cetaceans is put forward. It is shown that a combination of an unusually high number of glial cells and unihemispheric sleep phenomenology make the cetacean brain an efficient thermogenetic organ, which is needed to counteract heat loss to the water. It is demonstrated that water temperature is the major selection pressure driving an altered scaling of brain and body size and an increased actual brain size in cetaceans. A point in the evolutionary history of cetaceans is identified as the moment in which water temperature became a significant selection pressure in cetacean brain evolution. This occured at the Archaeoceti – modern cetacean faunal transition. The size, structure and scaling of the cetacean brain continues to be shaped by water temperature in extant cetaceans. The alterations in cetacean brain structure, function and scaling, combined with the imperative of producing offspring that can withstand the rate of heat loss experienced in water, within the genetic confines of eutherian mammal reproductive constraints, provides an explanation for the evolution of the large size of the cetacean brain. These observations provide an alternative to the widely held belief of a correlation between brain size and intelligence in cetaceans.
Conceptualising the child through an ‘ethic of care’: lessons for family law
Authors: Kelly Fiona
Published: March 2006

In this article I critically analyse the two historical models for conceptualising the child: the protectionist model and the children’s rights model. I argue that both models are inappropriate ways in which to conceptualise the child. Protectionism is paternalistic, essentialises the child, and denies the child a voice. Equally problematic, the children’s rights model presumes the social desirability of the liberal individual, and emphasises rights over relationships, and universal principles over concrete situations. Given the flaws inherent in these models, I propose a third way in which to conceptualise the child based on a feminist ‘ethic of care’. Drawing on the work of proponents of an ethic of care, I consider how the ethic might conceptualise the child, and how it might translate into a family law context.
Characterization of coherent magnetic fluctuations in JFT-2M high recycling steady high-confinement mode plasmas
Authors: Kamiya K. , Oyama N. , Ido T. , Bakhtiari M. ,   JFT-2M Group
Published: March 2006

The most important feature of the “high recycling steady” (HRS) high-confinement mode (H-mode) regime in the JFT-2M tokamak [H. Ninomiya et al., Fusion Science and Technology (2002), Vol. 42, p. 7] is the stationary pedestal condition in the absence of the large edge localized modes (ELMs). Accompanying the HRS H-mode transition, the coherent magnetic fluctuations in the frequency range of the order of 10–100kHz with significant variation are seen on the magnetic probes at the vessel wall. Above all, two types of edge magnetohydrodynamics (MHD) activities, which have associated toroidal mode number of n=1 and n∼7, respectively, seem to be more important for the HRS H-mode plasmas. To investigate their interaction, bispectral analysis is applied for the magnetic probe data, exhibiting the phase-coupled oscillations between two types of edge MHD activities. Parameter similarities and differences with small ELMs and stationary ELM-free H-mode regimes in other devices are also discussed.
Mesoscale simulation of morphology in hydrated perfluorosulfonic acid membranes
Authors: Wescott James T. , Qi Yue , Subramanian Lalitha , Weston Capehart T.
Published: March 2006

Current fuel cell proton exchange membranes rely on a random network of conducting hydrophilic domains to transport protons across the membrane. Despite extensive investigation, details of the structure of the hydrophilic domains in these membranes remain unresolved. In this study a dynamic self-consistent mean field theory has been applied to obtain the morphologies of hydrated perfluorosulfonic acid membranes (equivalent weight of 1100) as a model system for Nafion® at several water contents. A coarse-grained mesoscale model was developed by dividing the system into three components: backbone, side chain, and water. The interaction parameters for this model were generated using classical molecular dynamics. The simulated morphology shows phase separated micelles filled with water, surrounded by side chains containing sulfonic groups, and embedded in the fluorocarbon matrix. The size distribution and connectivity of the hydrophilic domains were analyzed and the small angle neutron scattering (SANS) pattern was calculated. At low water content (λ<6, where λ is the number of water molecules per sulfonic group) the isolated domains obtained from simulation are nearly spherical with a domain size smaller than that fitted to experimental SANS data. At higher water content (λ>8), the domains deform into elliptical and barbell shapes as they merge. The simulated morphology, hydrophilic domain size and shape are generally consistent with some experimental observations.
Electrolyte distribution around two like-charged rods: Their effective attractive interaction and angular dependent charge reversal
Authors: Jiménez-Ángeles Felipe , Odriozola Gerardo , Lozada-Cassou Marcelo
Published: March 2006

A simple model for two like-charged parallel rods immersed in an electrolyte solution is considered. We derived the three point extension (TPE) of the hypernetted chain/mean spherical approximation (TPE-HNC/MSA) and Poisson-Boltzmann (TPE-PB) integral equations. We numerically solve these equations and compare them to our results of Monte Carlo (MC) simulations. The effective interaction force, FT, the charge distribution profiles, ρel(x,y), and the angular dependent integrated charge function, P(θ), are calculated for this system. The analysis of FT is carried out in terms of the electrostatic and entropic (depletion) contributions, FE and FC. We studied several cases of monovalent and divalent electrolytes, for which the ionic size and concentration are varied. We find good qualitative agreement between TPE-HNC/MSA and MC in all the cases studied. The rod-rod force is found to be attractive when immersed in large size, monovalent or divalent electrolytes. In general, the TPE-PB has poor agreement with the MC. For large monovalent and divalent electrolytes, we find angular dependent charge reversal charge inversion and polarizability. We discuss the intimate relationship between this angular dependent charge reversal and rod-rod attraction.
Nonlinear evolution of the m=1 internal kink mode in the presence of magnetohydrodynamic turbulence
Authors: Bierwage Andreas , Benkadda Sadruddin , Hamaguchi Satoshi , Wakatani Masahiro
Published: March 2006

The nonlinear evolution of the m=1 internal kink mode is studied numerically in a setting where the tokamak core plasma is surrounded by a turbulent region with low magnetic shear. As a starting point, we choose configurations with three nearby q=1 surfaces where triple tearing modes (TTMs) with high poloidal mode numbers m are unstable. While the amplitudes are still small, the fast-growing high-m TTMs enhance the growth of the m=1 instability. This is interpreted as a fast sawtooth trigger mechanism. The TTMs lead to a partial collapse, leaving behind a turbulent belt with q≃1 around the unreconnected core plasma. Although, full reconnection can occur if the core displacement grows large enough, it is shown that the turbulence may actively prevent further reconnection. This is qualitatively similar to experimentally observed partial sawtooth crashes with post-cursor oscillations due to a saturated internal kink.
Linear analysis of a coaxial-waveguide gyrotron traveling-wave tube
Authors: Hung C. L.
Published: March 2006

Linear theory provides an efficient analysis model for the preliminary design of a gyrotron traveling-wave tube (gyro-TWT). This study presents a linear theory, which is applicable to amplifications or self-excited oscillations induced by absolute instabilities in a coaxial waveguide of finite length. The effects of wall losses are incorporated in the theoretical formalism. The validity of the linear theory is verified by comparison with calculation results obtained using an existing self-consistent nonlinear theory. The linear theory is applied to analyze a TE01 mode coaxial gyro-TWT at the fundamental cyclotron harmonic. Numerical analysis of coupling between the beam cyclotron mode and the waveguide mode provides physical insight into the wave-growing mechanisms of various oscillations. The critical parameters for the onset of threatening oscillation modes are analyzed to determine the stable operating conditions. Finally, the dependencies of small-signal amplifications on system parameters are studied in great detail.
Mutual information and electron correlation in momentum space
Authors: Sagar Robin P. , Guevara Nicolais L.
Published: March 2006

Mutual information and information entropies in momentum space are proposed as measures of the nonlocal aspects of information. Singlet and triplet state members of the helium isoelectronic series are employed to examine Coulomb and Fermi correlations, and their manifestations, in both the position and momentum space mutual information measures. The triplet state measures exemplify that the magnitude of the spatial correlations relative to the momentum correlations depends on and may be controlled by the strength of the electronic correlation. The examination of one- and two-electron Shannon entropies in the triplet state series yields a crossover point, which is characterized by a localized momentum density. The mutual information density in momentum space illustrates that this localization is accompanied by strong correlation at small values of p.
Effects of density gradient on short-bunch injection by wave breaking in the laser wake field acceleration
Authors: Ohkubo Takeru , Zhidkov Alexei , Hosokai Tomonao , Kinoshita Kenichi , Uesaka Mitsuru
Published: March 2006

Effects of density gradient on the self-injection of plasma electrons in the phase of laser pulse wake for further acceleration, is studied for moderate laser intensities, a0⩽3. It is shown that transverse wave breaking can shorten the length of accelerated electrons, whereas effective longitudinal wave breaking requiring steep plasma density interface increases their total charge. For the considered range of laser intensities, the total charge of electrons injected by wave breaking rises exponentially with a0.
An all-quartz gas cell for a multipass cavity
Authors: Fink M. , Campbell J.
Published: March 2006

The production of an all-quartz sample cell is described which has four window surfaces with 99.985% antireflective coatings. The cell is a part of a multipass cell for Raman spectroscopy of gases to determine isotopic abundances and low level impurities.
True fluid temperature reconstruction compensating for conduction error in the temperature measurement of steady fluid flows
Authors: Kobus Chris J.
Published: March 2006

There are three major types of errors that can cause a temperature probe to read a value different from the true fluid temperature into which it is immersed. One type is the transient temperature lag error in general purpose temperature sensors. Another is an error due to radiation heat transfer from walls at high temperatures. The other type is the error due to thermal energy conduction in lead wires and/or thermowell or other casing from a base on which the temperature probe is mounted. Although much study has been devoted to the former, very little exists on the latter. In fact, any prior research on this subject assumed that the entire sensor was completely immersed in the fluid, which in many cases is not true. For all of these types of errors, the cause is the misunderstanding that all physical sensor types only measure their own temperature, which may or may not be equal to the fluid temperature into which they are immersed. This article focuses on conduction error in temperature measurements and quantifies in simple terms a temperature error and lays out a general method for backing out (reconstructing) true fluid temperature from the sensor temperature measurement. Although only thermocouples are experimentally tested here, the theoretical work is valid for other types of physical sensors as well. The experimental verification for the model shows very good agreement.
Beam-single and beam-two-foil experimental facility to study physics of highly charged ions
Authors: Ahmad Nissar , Wani A. A. , Ram R. , Abhilash S. R. , Kumar Rakesh , Patnaik J. K. , De Sankar , Karn R. K. , Nandi T.
Published: March 2006

A facility for lifetime measurement of metastable states in highly charged ions using the beam-foil technique with a single-foil and a two-foil target has been developed. In the two-foil technique, one foil moves with respect to the other and the option of varying the thickness of the fixed foil online has been implemented. A holder with multiple foils is used as a fixed target, and moved along x, y, and θ, the angle of rotation with respect to beam direction along the z axis. Using this facility, the He-like 1s2pP2o3 and Li-like 1s2s2pP5∕2o4 titanium lifetimes have been measured and compared with earlier values. In addition to this, the processes which occur when excited states collide with carbon foils of different thicknesses have also been investigated. Preliminary results suggest the scope of studying intrashell transitions during ion-solid collision using this setup. In this article, the setup is described in detail and representative results are briefly discussed.
Fast heating stage for open liquid-cell atomic force microscopy
Authors: Kim Younghun , Choi Inhee , Kang Sung Koo , Lee Jeongjin , Yi Jongheop
Published: March 2006

A fast heating∕cooling stage designed for use in atomic force microscope imaging in liquid media was described. The proposed configuration was assembled by calculating the heat transfer coefficient for the heating∕cooling plate and the spacer. The air gap between the cooling jacket and scanner acted as a resist for the transfer of heat to the scanner, which induced by the thermal drift, cantilever bending, and nonlinearity of image. In this system, the tapping mode was negligibly affected by thermal stress of the heating stage, compared to the contact mode.
Absolute calibration of optical tweezers
Authors: Viana N. B. , Mazolli A. , Maia Neto P. A. , Nussenzveig H. M. , Rocha M. S. , Mesquita O. N.
Published: March 2006

As a step toward absolute calibration of optical tweezers, a first-principles theory of trapping forces with no adjustable parameters, corrected for spherical aberration, is experimentally tested. Employing two very different setups, we find generally very good agreement for the transverse trap stiffness as a function of microsphere radius for a broad range of radii, including the values employed in practice, and at different sample chamber depths. The domain of validity of the WKB (“geometrical optics”) approximation to the theory is verified. Theoretical predictions for the trapping threshold, peak position, depth variation, multiple equilibria, and “jump” effects are also confirmed.
Selective gas nanosensors with multisize CdSe nanocrystal/polymer composite films and dynamic pattern recognition
Authors: Potyrailo Radislav A. , Leach Andrew M.
Published: March 2006

We introduce a concept for selective chemical sensing based on different size semiconductor nanocrystals incorporated into a preselected polymer matrix. When CdSe nanocrystals of different sizes (2.8 and 5.6nm diam) were incorporated into a polymer film, each size of the nanocrystals demonstrated a distinct photoluminescence response pattern (excitation at λ=407nm) upon exposure to polar and nonpolar vapors in air at atmospheric pressure. When this composite response was processed using a multivariate analysis, a single film with different size CdSe nanocrystals served as a selective sensor.
Nanobox array for silicon-on-insulator luminescence enhancement at room temperature
Authors: Cluzel B. , Pauc N. , Calvo V. , Charvolin T. , Hadji E.
Published: March 2006

We report the light extraction enhancement obtained at room temperature from a square lattice of crystalline silicon nanoboxes etched in a silicon-on-insulator substrate. Luminescence spectra recorded under optical pumping show a 125 times emission enhancement as compared with the reference unpatterned silicon-on-insulator emission. In light of band diagram calculations, it is demonstrated that the emission enhancement partially results from the coupling between electron-hole recombination inside the silicon boxes and low group velocity optical modes of the array. Moreover, it is observed that these modes present different decoupling lengths and that a complete extraction of luminescence can be achieved over less than 15μm.
Phase transformation and electric field tunable pyroelectric behavior of Pb(Nb,Zr,Sn,Ti)O3 and (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric thin films
Authors: Xu Zhengkui , Zhai Jiwei , Chan Wai-Hung , Chen Haydn
Published: March 2006

Phase transformation and pyroelectric behavior of Pb(Nb,Zr,Sn,Ti)O3 (PNZST) and (Pb,La)(Zr,Sn,Ti)O3 (PLZST) antiferroelectric (AFE) thin films were investigated as a function of temperature and dc bias field. A large pyroelectric coefficient of the order of ∼3×10−7Ccm−2K−1 was realized at the ferroelectric (FE) to AFE and the AFE to FE phase transformations in the PLZST and PNZST films, respectively. The phase transformation temperature could be readily adjusted by dc bias for both films. The large pyroelectric coefficient combined with excellent dc tunability at the phase transformation temperature makes these two systems promising candidates for uncooled tunable pyroelectric thermal sensing applications.
Experimental study of the acoustic radiation strain in solids
Authors: Jacob Xavier , Takatsu Ryota , Barrière Christophe , Royer Daniel
Published: March 2006

Measurements of the static displacement induced by the radiation stress associated with a longitudinal acoustic wave propagating in a solid are presented. Acoustic tone bursts were launched into fused silica and duraluminum samples. The static displacement was measured at the sample free surface with an optical interferometer. The role of the nonlinearity parameter and the variations of the dc pulse amplitude with the acoustic energy confirm results obtained by other authors. However, our conclusions on the dc pulse shape, on the influence of the tone burst duration, and of the propagation distance on the dc pulse amplitude are different.
Finite-temperature magnetism of tetragonal iron
Authors: Wang Jian-Tao , Wang Ding-Sheng , Kawazoe Y.
Published: March 2006

Based on ab initio Monte Carlo approach, finite-temperature magnetism of tetragonal Fe is studied. It is shown that the ground state magnetic structure changes from ferromagnetic to antiferromagnetic as the structure transforms from bcc to fcc. The Curie temperature (TC) or Néel temperatures (TN) are very sensitive to the lattice distortion, which decreases from bcc to fcc and then increases over the fcc range. There are a maximum of TC at the bcc and a minimum of TN around the fcc limit due to the change of the coupling distance and symmetry consideration.
Efficient single-active-layer organic light-emitting diodes with fluoropolymer buffer layers
Authors: Wang H. F. , Wang L. D. , Wu Z. X. , Zhang D. Q. , Qiao J. , Qiu Y. , Wang X. G.
Published: March 2006

In the present Letter, efficient organic light-emitting diodes (OLEDs) with tris(8-hydroxyquinolino) aluminum (Alq3) as a single-active layer have been prepared by using a series of fluoropolymer buffer layers. The OLEDs with a 10-nm-thick poly(tetrafluroethylene-perfluoroalkylvinylethers) (PFA) buffer layer had a current efficiency of 4.46cd∕A at a current density of 2000A∕m2, whereas conventional double-layer OLEDs with N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) and Alq3 showed a current efficiency of only 3.81cd∕A at the same condition in our experiment. The effect of the insulating fluoropolymer buffer layers could be interpreted to enhance hole injection and improve carrier balance.
Measuring the role of surface chemistry in silicon microphotonics
Authors: Borselli Matthew , Johnson Thomas J. , Painter Oskar
Published: March 2006

Utilizing a high quality factor (Q∼1.5×106) optical microresonator to provide sensitivity down to a fractional surface optical loss of αs′∼10−7, we show that the optical loss within Si microphotonic components can be dramatically altered by Si surface preparation, with αs′∼1×10−5 measured for chemical oxide surfaces as compared to αs′⩽1×10−6 for hydrogen-terminated Si surfaces. These results indicate that the optical properties of Si surfaces can be significantly and reversibly altered by standard microelectronic treatments, and that stable, high optical quality surface passivation layers will be critical in future Si micro- and nanophotonic systems.
Fiber-content dependency of the optical transparency and thermal expansion of bacterial nanofiber reinforced composites
Authors: Nogi Masaya , Ifuku Shinsuke , Abe Kentaro , Handa Keishin , Nakagaito Antonio Norio , Yano Hiroyuki
Published: March 2006

We produced transparent nanocomposite reinforced with bacterial cellulose having a wide range of fiber contents, from 7.4to66.1wt%, by the combination of heat drying and organic solvent exchange methods. The addition of only 7.4wt% of bacterial cellulose nanofibers, which deteriorated light transmittance by only 2.4%, was able to reduce the coefficient of thermal expansion of acrylic resin from 86×10−6to38×10−6K−1. As such, the nanofiber network of bacterial cellulose has an extraordinary potential as a reinforcement to obtain optically transparent and low thermal expansion materials.
Nano-Raman mapping of porous glass ceramics with a scanning near-field optical microscope in collection mode
Authors: Zavalin A. , Cricenti A. , Generosi R. , Luce M. , Morgan S. , Piston D.
Published: March 2006

A nano-Raman setup using the optical fiber of a scanning near-field optical microscope, working in collection mode, is described and applied to mapping of TiO2∕PO4 phase distribution in glass ceramics. This material is extremely important as a surface-enhanced raman scattering substrate for biological and chemical analyses. The collected Raman signal in this near-field geometry reaches spatial resolutions better than 100nm, well below the diffraction limit.
Analytical model for incomplete signal generation in semiconductor detectors
Authors: Kim Ho Kyung
Published: March 2006

Signal generation from semiconductor detectors has been modeled considering incomplete charge signal due to the charge trapping within a detector as well as to the ballistic deficit caused by insufficient charge collection time. The analytical formalism was experimentally confirmed with the charge collection efficiency of a planar mercuric iodide (HgI2) detector. The developed model is useful for the characterization of detector material properties such as the mobility and the lifetime, as well as the optimization of operation conditions such as the applied bias and the charge collection time.
Generation and detection of terahertz coherent transverse-polarized acoustic phonons by ultrafast optical excitation of GaAs∕AlAs superlattices
Authors: Kini R. N. , Kent A. J. , Stanton N. M. , Henini M.
Published: March 2006

We have used femtosecond pump-probe techniques to generate and detect coherent transverse and quasitransverse polarized acoustic phonons in GaAs∕AlAs superlattices. Direct generation of transverse phonons is achieved using superlattices grown on the low-symmetry, (311) and (211), crystal planes. The frequency of the generated phonons is determined by the superlattice period and is in the region of 0.4THz. The dependence of the mode structure on the pump polarization suggests that a Raman scattering process is responsible for coherent phonon generation. Using bolometers on the back surface of the substrate, we show that the transverse phonons leak out of the superlattice and propagate over macroscopic distances at low temperature.
Ultrafast spectroscopy of impact ionization and avalanche multiplication in GaAs
Authors: Trumm S. , Betz M. , Sotier F. , Leitenstorfer A. , Schwanhäußer A. , Eckardt M. , Schmidt O. , Malzer S. , Döhler G. H. , Hanson M. , Driscoll D. , Gossard A. C.
Published: March 2006

Femtosecond carrier dynamics in biased AlxGa1−xAs heterostructure diodes is investigated tracing transient modifications of the Franz-Keldysh absorption spectrum. The nonlinear optical response is sensitive to the number of electron-hole pairs in the high-field region of the sample. As a result, the dynamical buildup of a nonequilibrium carrier avalanche due to impact ionization for electric fields F⩾350kV∕cm is directly analyzed in the time domain. The time scale of the carrier multiplication is found to be in the order of 10ps depending on the number of photoinjected carriers. Monte Carlo simulations in a simplified band structure agree well with the experiment.
Photoluminescence study of ZnO nanotubes under hydrostatic pressure
Authors: Chen S. J. , Liu Y. C. , Shao C. L. , Xu C. S. , Liu Y. X. , Liu C. Y. , Zhang B. P. , Wang L. , Liu B. B. , Zou G. T.
Published: March 2006

Photoluminescence of ZnO single crystal nanotubes grown on sapphire substrate by metal organic chemical vapor deposition has been studied as a function of applied hydrostatic pressure using the diamond-anvil-cell technique. The photoluminescence spectra of the ZnO nanotubes at atmospheric pressure are dominated by strong near-band-edge ΓFX and ΓBX excitonic emission lines accompanied by a weak broad deep-level (DL) emission band. The pressure-induced shifts of all observed emission lines are followed up to 15Gpa, when ZnO nanotubes undergo a phase transition from a direct-gap wurtzite structure to an indirect-gap rocksalt structure. The ΓFX emission is found to shift toward higher energy with applied pressure at a rate of 29.6meV∕GPa, which provides a method to measure the pressure coefficient of the direct Γ band gap in the wurtzite ZnO nanotubes. The ΓBX emission has a pressure coefficient of 21.6meV∕GPa, about 30% smaller than that of the ZnO band gap, which suggests that it might originate from the radiative recombination of the excitons bound to donorlike deep centers rather than shallow donors. The pressure coefficient of the broad DL emission band in ZnO tube is 16.8meV∕GPa, which indicates that the initial states involved in the emission process are deep localized states.
Cladding mode resonances of etch-eroded fiber Bragg grating for ambient refractive index sensing
Authors: Chen Na , Yun Binfeng , Cui Yiping
Published: March 2006

In this Letter, the cladding mode resonances of a chemical etch-eroded fiber Bragg grating are proposed for highly sensitive ambient refractive index sensing. The varying characteristics of several different order cladding mode resonances with ambient refractive index are explored experimentally. The maximum sensing sensitivity of 172nm∕riu for the third-order cladding mode resonance is achieved in the experiments. Under the same cladding diameter, the cladding mode resonances have narrower bandwidth and response much more sensitive to the ambient refractive index changing than conventional Bragg core mode resonance, which would enable them to achieve a higher resolution.
Fibrillin expression is regulated by abscisic acid response regulators and is involved in abscisic acid-mediated photoprotection
Authors: Yang Yi , Sulpice Ronan , Himmelbach Axel , Meinhard Michael , Christmann Alexander , Grill Erwin
Published: March 2006

Fibrillins are lipid-binding proteins of plastids that are induced under abiotic stress conditions. In response to environmental stress, plants generate abscisic acid (ABA) as an endogenous signal. We show that ABA treatment and fibrillin accumulation enhance the tolerance of photosystem II toward light stress-triggered photoinhibition in
Arabidopsis
. ABA induces fibrillin accumulation, and the ABA response regulators ABI1 and ABI2 regulate fibrillin expression. The abundance of fibrillin transcripts was specifically reduced in the ABA-insensitive
abi1
mutant but not in the
abi2
mutant. However, leaves of
abi2
revealed in comparison to WT and
abi1
enhanced fibrillin levels, pointing to a posttranscriptional control mechanism. Protein interaction analysis identified the protein phosphatase ABI2 to target the preprotein of fibrillin. Interaction was abrogated either by deleting the signal peptide of prefibrillin or by the single amino acid exchange present in the phosphatase-deficient abi2 protein. Thus, ABI1 and ABI2 seem to control fibrillin expression that is involved in mediating ABA-induced photoprotection.
Malaria resurgence in the East African highlands: Temperature trends revisited
Authors: Pascual M. , Ahumada J. A. , Chaves L. F. , Rodó X. , Bouma M.
Published: March 2006

The incidence of malaria in the East African highlands has increased since the end of the 1970s. The role of climate change in the exacerbation of the disease has been controversial, and the specific influence of rising temperature (warming) has been highly debated following a previous study reporting no evidence to support a trend in temperature. We revisit this result using the same temperature data, now updated to the present from 1950 to 2002 for four high-altitude sites in East Africa where malaria has become a serious public health problem. With both nonparametric and parametric statistical analyses, we find evidence for a significant warming trend at all sites. To assess the biological significance of this trend, we drive a dynamical model for the population dynamics of the mosquito vector with the temperature time series and the corresponding detrended versions. This approach suggests that the observed temperature changes would be significantly amplified by the mosquito population dynamics with a difference in the biological response at least 1 order of magnitude larger than that in the environmental variable. Our results emphasize the importance of considering not just the statistical significance of climate trends but also their biological implications with dynamical models.
Experimental autoimmune encephalomyelitis disrupts endocannabinoid-mediated neuroprotection
Authors: Witting Anke , Chen Lanfen , Cudaback Eiron , Straiker Alex , Walter Lisa , Rickman Barry , Möller Thomas , Brosnan Celia , Stella Nephi
Published: March 2006

Focal cerebral ischemia and traumatic brain injury induce an escalating amount of cell death because of harmful mediators diffusing from the original lesion site. Evidence suggests that healthy cells surrounding these lesions attempt to protect themselves by producing endocannabinoids (eCBs) and activating cannabinoid receptors, the molecular target for marijuana-derived compounds. Indeed, activation of cannabinoid receptors reduces the production and diffusion of harmful mediators. Here, we provide evidence that an exception to this pattern is found in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. We show that cell damage induced by EAE does not lead to increase in eCBs, even though cannabinoid receptors are functional because synthetic cannabinoid agonists are known to confine EAE-induced lesions. This lack of eCB increase is likely due to IFN-γ, which is released by primed T cells invading the CNS. We show that IFN-γ disrupts the functionality of purinergic P2X
7
receptors, a key step controlling eCB production by microglia, the main source of eCBs in brain. Accordingly, induction of EAE in P2X
7
−/−
mice results in even lower eCB levels and more pronounced cell damage than in wild-type mice. Our data suggest that the high level of CNS IFN-γ associated with EAE disrupts eCB-mediated neuroprotection while maintaining functional cannabinoid receptors, thus providing additional support for the use of cannabinoid-based medicine to treat multiple sclerosis.
Characterization of mitochondrial ferritin in
Drosophila
Authors: Missirlis Fanis , Holmberg Sara , Georgieva Teodora , Dunkov Boris C. , Rouault Tracey A. , Law John H.
Published: March 2006

Mitochondrial function depends on iron-containing enzymes and proteins, whose maturation requires available iron for biosynthesis of iron–sulfur clusters and heme. Little is known about how mitochondrial iron homeostasis is maintained, although the recent discovery of a mitochondrial ferritin in mammals and plants has uncovered a potential key player in the process. Here, we show that
Drosophila melanogaster
expresses mitochondrial ferritin from an intron-containing gene. It has high similarity to the mouse and human mitochondrial ferritin sequences and, as in mammals, is expressed mainly in testis. This ferritin contains a putative mitochondrial targeting sequence and an epitope-tagged version localizes to mitochondria in transfected cells. Overexpression of mitochondrial ferritin fails to alter both total-body iron levels and iron that is bound to secretory ferritins. However, the viability of iron-deficient flies is compromised by overexpression of mitochondrial ferritin, suggesting that it may sequester iron at the expense of other important cellular functions. The conservation of mitochondrial ferritin in an insect species underscores the importance of this iron-storage molecule.
Experimental taphonomy shows the feasibility of fossil embryos
Authors: Raff Elizabeth C. , Villinski Jeffrey T. , Turner F. Rudolf , Donoghue Philip C. J. , Raff Rudolf A.
Published: March 2006

The recent discovery of apparent fossils of embryos contemporaneous with the earliest animal remains may provide vital insights into the metazoan radiation. However, although the putative fossil remains are similar to modern marine animal embryos or larvae, their simple geometric forms also resemble other organic and inorganic structures. The potential for fossilization of animals at such developmental stages and the taphonomic processes that might affect preservation before mineralization have not been examined. Here, we report experimental taphonomy of marine embryos and larvae similar in size and inferred cleavage mode to presumptive fossil embryos. Under conditions that prevent autolysis, embryos within the fertilization envelope can be preserved with good morphology for sufficiently long periods for mineralization to occur. The reported fossil record exhibits size bias, but we show that embryo size is unlikely to be a major factor in preservation. Under some conditions of death, fossilized remains will not accurately reflect the cell structure of the living organism. Although embryos within the fertilization envelope have high preservation potential, primary larvae have negligible preservation potential. Thus the paleo-embryological record may have strong biases on developmental stages preserved. Our data provide a predictive basis for interpreting the fossil record to unravel the evolution of ontogeny in the origin of metazoans.
Bone mineral density is reduced in brain tumour patients treated in childhood
Authors: Pietilä Sari , Sievänen Harri , Ala‐Houhala Marja , Koivisto Anna‐Maija , Lenko Hanna Liisa , Mäkipernaa Anne
Published: March 2006

Aim: To determine the prevalence of low bone mineral density among children surviving brain tumours and to identify possible factors underlying impaired bone health. Methods: Cross‐sectional study; total body bone mineral density (TBBMD), fat mass (FM) and lean body mass (LBM) were measured by dual‐energy X‐ray absorptiometry (DXA) in 46 brain tumour patients aged from 3.8 to 28.7 y (mean 14.9 y) treated in childhood 1.4–14.8 y (mean 6.4 y) after end of treatment for brain tumour. Low bone mineral density was defined as TBBMD z score<−2.0. Results: Fifteen patients had TBBMD z scores<−2.0, indicating a 33% prevalence of low bone density. The TBBMD z score ranged from −5.7 to 0.6 (mean −1.7). Out of several potential factors, only combined craniospinal irradiation was significantly associated with low z score (p=0.034, according to multiple regression analysis), while exclusive cranial irradiation showed a borderline statistical association (p=0.100, according to multiple regression analysis).

Conclusion: One third of brain tumour patients treated in childhood had reduced bone mineral density. The reasons for this condition are apparently multifactorial, including craniospinal irradiation.
Properdin deficiency in a boy with fulminant meningococcal septic shock
Authors: Genel Ferah , Atlihan Fusun , Gulez Nesrin , Sjöholm Anders G. , Skattum Lillemor , Truedsson Lennart
Published: March 2006

Bacterial meningitis is a rare presentation for congenital immunodeficiency, but meningococcal invasive diseases and meningitis have been associated with late complement component deficiencies and properdin deficiency. A 5½‐y‐old boy of non‐consanguineous parents was admitted to our hospital with meningococcal septic shock. He had previously been suffering from recurrent respiratory infections. His 13‐y‐old brother had also been treated for meningococcal meningitis when he was 7 y old. Immunological studies, done after recovery, on the patient and his two brothers revealed normal immunoglobulin, IgG subclasses, C3, C4 and CH50 levels. Haemolytic activity of the alternative complement pathway could not be detected, and properdin concentrations were <0.01 mg/l in serum samples from the patient and his brothers. The patient and family members received quadrivalent polysaccharide meningococcal vaccine. The patient was discharged on penicillin prophylaxis, and he remained healthy during the ensuing year.

Conclusion: Our findings stress that measurement of the haemolytic activity of the alternative complement pathway in addition to classical pathway haemolytic complement activity should be performed in patients with meningococcal disease to reveal various forms of complement deficiency. This is particularly important when there is a family history, or recurrences or infection due to uncommon serogroups. Deficient individuals and affected family members might be protected from infection by vaccination.
The prophylactic and therapeutic effectiveness of zinc sulphate on common cold in children
Authors: Kurugöl Zafer , Akilli Münevver , Bayram Nuri , Koturoglu Guldane
Published: March 2006

Aim: To determine the efficacy of prophylactic administration of zinc sulphate in reducing the occurrence of the common cold in children, and to evaluate the efficacy of zinc sulphate in reducing the duration and severity of cold symptoms. Methods: A total of 200 healthy children were randomly assigned to receive oral zinc sulphate (zinc group, n=100) or placebo (placebo group, n=100). Zinc sulphate (15 mg of zinc) or placebo syrup were administered for prophylaxis once daily during a 7‐mo study period. The dose was increased to two times per day (30 mg of zinc) at the onset of cold, until symptoms resolved. Results: The mean number of colds in the zinc group was significantly less than in the placebo group (1.2 vs 1.7 colds per child; p=0.003). The mean cold‐related school absence was 0.9 d per child in the zinc group versus 1.3 d in the placebo group (p=0.04). Compared to the placebo group, the zinc group had shorter mean duration of cold symptoms and decreased total severity scores for cold symptoms (p<0.0001). Adverse effects were mild and similar in both groups.

Conclusion: Zinc sulphate appears to be an easily administered, safe and well‐tolerated alternative for the prevention and treatment of the common cold in children.
Circulating adiponectin levels in Kawasaki disease
Authors: Takeshita Seiichiro , Takabayashi Humiyo , Yoshida Naoki
Published: March 2006

Aim: To investigate the kinetics of adipocytokine in Kawasaki disease (KD). Methods: The plasma levels of adiponectin, IL‐6 and TNF‐α were measured in 20 patients with KD, 15 patients with acute febrile diseases (disease control, DC) and 15 healthy children (HC). Results: Plasma adiponectin levels in patients with acute KD were significantly lower (p<0.01) than those with convalescent KD, DC and HC. The decreased levels of adiponectin negatively correlated with the increased levels of CRP and IL‐6 in acute KD.

Conclusion: Hypoadiponectinaemia was shown during the acute phase of KD vasculitis. The downregulation of adiponectin secreted from adipose tissue may be closely linked to upregulation of systemic pro‐inflammatory markers in acute KD.
Steroid fears in children with eczema
Authors: Hon Kam‐Lun Ellis , Kam Wai‐Yan Christy , Leung Ting‐Fan , Lam Man‐Ching Adrian , Wong Kin‐Yee , Lee Kwing‐Chin Kenneth , Luk Nai‐Ming Tommy , Fok Tai‐Fai , Ng Pak‐Cheung
Published: March 2006

Background: Topical glucocorticoids (GCs) are the mainstay of treatment for eczema, but GC phobia and fears are very common among the parents of paediatric patients. Aim: To survey the nature and extent of “fears” of GC use, and to evaluate if disease severity is associated with such fears. Methods: Patients with eczema managed in the paediatric dermatology outpatient clinic of a university hospital were recruited in this survey. Disease severity and various aspects of belief and practices of GC use were assessed with the Nottingham Eczema Severity Score and a questionnaire. Results: GC “fears” were present in two fifths of informants with non‐eczematous skin disease and mild eczema, but three fifths in moderate‐to‐severe disease. Requests for steroid‐sparing medications (such as tacrolimus or pimecrolimus) had been made in nearly 50% of cases with moderate‐to‐severe eczema, and many parents would wait until eczema had worsened or apply GC only as a last resort to avoid potential side effects. “Fears” were predominantly interpersonal and rarely iatrogenic in nature. Skin problems (in particular skin thinning) and adverse effects on growth were the side effects of GC of most concern. However, fewer than half of the informants had discussed their concerns with doctors.

Conclusion: Our results suggest the importance of understanding the nature and extent to which GC fears, regardless of eczema severity, are prevalent so that sound advice can be offered in a timely manner to parents and patients.
Injection Practices in Romania Progress and Challenges
Authors: Dentinger Catherine , Pasat Lili , Popa Mircea , Hutin Yvan J. F. , Mast Eric E.
Published: March 2006

Objective:

To identify breaks in infection control practices that might put Romanians at risk for transmission of hepatitis B virus (HBV) from injections.

Methods:

A standardized questionnaire was administered to a systematic sample of the 1,906 nurses in Valcea District, Romania, to collect information on their knowledge, attitudes, and practices regarding injection administration and universal precautions.

Results:

Of the 180 nurses interviewed, 91% (95% confidence interval [CI95], 86% to 95%) reported having attended training for universal precautions; 58% (CI95, 49% to 67%) accurately reported that HBV remains infectious for at least 1 week in the environment; and 4% (CI95, 2% to 8%) knew that HBV is transmitted more efficiently than HrV through percutaneous exposures. No nurses reported reusing syringes or needles on different patients, but 4 (2%; CI95, 1% to 6%) would reuse a syringe and 3 (2%; CI95, 0% to 5%) would reuse a needle on the same patient in an emergency. Fifty-three percent (CI95, 44% to 61%) of nurses reported having a dedicated area for the preparation of injectable medications separate from where blood-contaminated items were handled. Shortages of infection control supplies were common.

Conclusions:

Although nurses in Valcea do not report reusing injection equipment without sterilization, other unsafe practices occur that may facilitate HBV transmission through injections, including preparing injectable medications in areas potentially contaminated with blood. Inadequate knowledge of blood-borne pathogen transmission and shortages of infection control supplies may contribute to these unsafe practices. Addressing these deficits could improve injection safety in Romania.
An Approach to the Study of Potentially Preventable Nosocomial Infections
Authors: Rosselló-Urgell José , Vaqué-Rafart Josep , Hermosilla-Pérez Eduardo , Allepuz-Palau Alejandro ,   EPINE Working Group
Published: March 2006

Objective:

To analyze a method that identifies potentially preventable nosocomial infections, as a tool to evaluate the performance of infection control programs through quantification of their potential for reducing nosocomial infections.

Methods:

The database of the Study of the Prevalence of Nosocomial Infections in Spain (EPINE) was reanalyzed. The method was based on the use of false negatives of the classification table obtained from application of a fixed multiple logistic regression model, as an estimator of the number of potentially preventable nosocomial infections.

Results:

The calculated number of patients with preventable infections was 7,493, which constituted 21.6% of the infected patients. Among hospital areas, intensive care had the lowest preventability rate (4.6%), whereas gynecology and obstetrics had the highest (40.6%). There was a significant inverse exposure-effect relationship between the proportion of preventable infections and the National Nosocomial Infections Surveillance (NNIS) System risk index. No correlation was observed between the prevalence of patients with nosocomial infection and the percentage of preventable infections.

Conclusion:

This analysis suggests that fewer nosocomial infections may be preventable in Spanish hospitals than previously assumed.
Footwear Exchange Has No Influence on the Incidence of Febrile Neutropenia in Patients Undergoing Chemotherapy for Hematologic Malignancies
Authors: Sugahara Hiroyuki , Mizuki Masao , Matsumae Sayoko , Nabetani Yoshiko , Kikuchi Motoko , Kanakura Yuzuru
Published: March 2006

Objective:

To determine whether footwear exchange affects the incidence of febrile neutropenia among patients undergoing chemotherapy for hematologic malignancies.

Design:

Open trial with historical comparison.

Setting:

The 12-bed high-efficiency particulate air-fil-tered hematology unit at Osaka University Hospital, Suita, Japan.

Patients:

Those with hematologic malignancies who underwent chemotherapy from January 1997 through January 2003. Footwear exchange was discontinued in January 2000.

Methods:

The surveillance system was based on the National Nosocomial Infections Surveillance System of the Centers for Disease Control and Prevention. Rates of febrile neutropenia were calculated for neutropenic patient-days (ie, days with neutropenia < 500/μL).

Results:

From January 1997 through December 1999 and from February 2000 through January 2003, 58 and 54 patients endured 237 and 184 neutropenic periods following chemotherapy, and their total neutropenic days were 3,123 and 2,503, respectively. They showed episodes of febrile neutropenia 89 and 68 times, respectively. Infection rates were 28.5 and 27.2 per 1,000 neutropenic patient-days (P = .83), respectively.

Conclusion:

The incidence of febrile neutropenia was not affected by footwear exchange. In hematology units, changing shoes does not appear to affect the rate of infections during neutropenic periods.