bluuebunny/crossref_metadata_2025 huggingface dataset:
Free‐form estimation of the unsaturated soil hydraulic properties by inverse modeling using global optimization
Authors: Iden S. C. , Durner W.
Published: July 2007

Inverse modeling is a powerful technique for identifying the hydraulic properties of unsaturated porous media. However, the selection of an appropriate parameterization of the soil water retention and hydraulic conductivity function remains a challenge. In this article, we present an improved algorithm for estimating these two relationships without assigning an a priori shape to them. The approach uses cubic Hermite interpolation and a global optimization strategy. A multilevel routine identifies the adequate number of degrees of freedom by balancing model performance, the statistical interaction of the estimated model parameters, and their number. A first‐order uncertainty analysis provides a quantitative measure of how well the soil hydraulic properties can be identified in different ranges of pressure head. This offers great potential for designing optimal experimental procedures for identifying the hydraulic properties of porous media. We demonstrate the effectiveness of the algorithm for the evaluation of multistep outflow experiments by investigating synthetic data sets and real measurements. The free‐form approach yields optimal model parameters that show only moderate correlation, indicating well‐posed inverse problems. Since parameterization errors are almost completely avoided, the algorithm is well suited to identifying other error sources in unsaturated flow problems, e.g., limitations in the applicability of the Richards equation or problems caused by spatial heterogeneity.
Understanding the effects of atmospheric circulation in the relationships between water vapor and temperature through theoretical analyses
Authors: Lu Er
Published: July 2007

Theoretical analyses are provided to understand the effects of the atmospheric circulation in the relationships between water vapor and temperature. Relative humidity (r) analysis indicates that when temperature variation range ΔT ≡ T2 − T1 is larger than Dr ≡ 13 ln(r1/r2), a measure of the decrease of r over the temperature range, strong positive correlations can be expected between water vapor and temperature. Dynamic process analysis reveals, with expressing the change of water vapor as ΔW = fΔT + B (f > 0 and B represents atmospheric dynamic effect), the dual effects of the atmospheric circulation in the water vapor‐temperature relationships. When ΔT is large so that fΔT > ∣B∣, the thermodynamic effect of the earth‐atmosphere is more important; the thermally induced atmospheric circulation and the evaporation tend to establish strong positive correlations between water vapor and temperature. When ΔT is small so that fΔT < ∣B∣, the dynamic effect of the atmosphere is more important; the dynamic water vapor convergence and divergence make water vapor and temperature have weak correlations.
A reassessment of global and regional mean sea level trends from TOPEX and Jason‐1 altimetry based on revised reference frame and orbits
Authors: Beckley B. D. , Lemoine F. G. , Luthcke S. B. , Ray R. D. , Zelensky N. P.
Published: July 2007

Mean sea level trends from TOPEX and Jason‐1 altimeter data are recomputed using unified geophysical modeling and the new ITRF2005 terrestrial reference frame for the entire altimetric time series, with consistent orbits based on satellite laser ranging (SLR) and DORIS tracking data. We obtain a global rate of 3.36 ± 0.41 mm/yr over the 14 year period from 1993 to 2007. The regional sea level trends computed with the new reference frame show significant north/south hemispherical offsets of ±1.5 mm/yr relative to trends based on the previous 1995‐era frame. Regional sea level trend comparisons for the time periods of 1993–1999 and 1999–2005 reveal strong basin‐scale polarities and pronounced inter‐decadal variability, with a relative increase in the global mean sea level trend of 1.5 ± 0.7 mm/yr in the latter seven years.
Complex variables for separation of the Hamilton-Jacobi equation on real pseudo-Riemannian manifolds
Authors: Degiovanni Luca , Rastelli Giovanni
Published: July 2007

In this paper the geometric theory of separation of variables for the time-independent Hamilton-Jacobi equation is extended to include the case of complex eigenvalues of a Killing tensor on pseudo-Riemannian manifolds. This task is performed without complexifying the manifold but just by considering complex-valued functions on it. The simple formalism introduced in the paper allows us to extend in a very natural way the classical results on separation of variables (including Levi-Civita criterion and Stäckel-Eisenhart theory) to the complex case. Only orthogonal variables are considered.
Rovibronic bands of the Ã←X̃ transition of CH3OO and CD3OO detected with cavity ringdown absorption near 1.2–1.4μm
Authors: Chung Chao-Yu , Cheng Chi-Wen , Lee Yuan-Pern , Liao Hsin-Yi , Sharp Erin N. , Rupper Patrick , Miller Terry A.
Published: July 2007

We have recorded several rovibronic bands of CH3OO and CD3OO in their Ã←X̃ transitions in the range of 1.18–1.40μm with the cavity ringdown technique. While the electronic origins for these species have been reported previously, many newly observed rovibronic bands are described here. The experimental vibrational frequencies (given as ν in the unit cm−1 in this paper) for the COO bending (ν8) and COO symmetric stretching (ν7) modes in the Ã state are 378 and 887cm−1 for CH3OO, and 348 and 824cm−1 for CD3OO, respectively. In addition, two other vibrational frequencies were observed for the Ã state of CD3OO, namely, ν5 (954cm−1) and ν6 (971cm−1). These experimental vibrational frequencies for the Ã state of both CH3OO and CD3OO are in good agreement with predictions from quantum-chemical calculations at the UB3LYP/aug-cc-pVTZ level. The enhanced activity of the ν5 vibrational mode in CD3OO is rationalized by mode mixing with the ν7 mode, as supported by calculations of multidimensional Franck-Condon factors. In addition, many hot bands involving the methyl torsional mode (ν12) are observed for both normal and deuterated methyl peroxy. These bands include the “typical” sequence transitions and some “atypical” ones due to the nature of the eigenvalues and eigenfunctions which are a consequence of the low, but very different, torsional barriers in the X̃ and Ã states. In addition, the 1222 band in CH3OO and the 1233 band in CD3OO show quite different structures than the origin bands, an effect which results from tunneling splittings comparable to the rotational contour.
Vibrationally selective optimal control of alignment and orientation using infrared laser pulses: Application to carbon monoxide
Authors: Zou Shiyang , Balint-Kurti Gabriel G. , Manby Frederick R.
Published: July 2007

Optimal control methods are used to study molecular alignment and orientation using infrared laser pulses. High order molecule-field interactions are taken into account through the use of the electric-nuclear Born-Oppenheimer approximation [G. G. Balint-Kurti et al., J. Chem. Phys. 122, 084110 (2005)]. High degrees of alignment and orientation are achieved by optimized infrared laser pulses of duration on the order of one rotational period of the molecule. It is shown that, through the incorporation of a vibrational projection operator into the optimization procedure, it is possible not only to maximize the alignment and orientation but also to bring the whole system into a single prescribed vibrational manifold. Numerical calculations are performed for carbon monoxide using ab initio potential energies computed in the presence of external electric fields.
Assignment of rovibrational transitions of propyne in the region of 2934–2952cm−1 measured by two-color IR–vacuum ultraviolet laser photoion-photoelectron methods
Authors: Xing Xi , Reed Beth , Lau Kai-Chung , Baek Sun-Jong , Bahng Mi-Kyung , Ng C. Y.
Published: July 2007

The infrared (IR) spectrum of propyne in the region of 2934–2952cm−1 has been recorded by the IR–vacuum ultraviolet (VUV)–photoion method. The spectrum is shown to consist of two near-resonant, but noncoupled vibrational bands: the ν2 symmetric methyl C–H stretching vibrational band and a combination vibrational band νcs. The previously unobserved Q line of the νcs band is observed. The rotational transition lines of the ν2=1 band produces IR-VUV–pulsed field ionization–photoelectron (IR-VUV-PFI-PE) signal at the C3H4+ (ν2+=1) photoionization threshold. The rotational transition lines associated with the νcs band do not produce IR-VUV-PFI-PE signal. Rotational transition lines of both vibrational bands are assigned and simulated; and ab initio calculations further confirm the assignment.
Internal friction peak associated with the interface motion in the martensitic transformation of CuAlNiMnTi shape memory alloy
Authors: Gong C. L. , Han F. S. , Li Z. , Wang M. P.
Published: July 2007

Two internal friction peaks were observed in a CuAlNiMnTi polycrystalline shape memory alloy during the martensitic transformation through an incomplete phase transformation method, of which the high-temperature peak PH is discussed in the present study. It has been found that the PH peak is discernible only at relatively low frequencies and its maximum corresponds to the inflection point of the relative dynamic modulus rather than its minimum, i.e., this peak is related to a process without soft mode effect. An internal friction model is proposed to describe the PH peak based on the theory of phase nucleation and growth in the thermoelastic martensitic transformation and is verified by the experimental results.
Optical tweezers in interaction with an apertureless probe
Authors: Chaumet Patrick C. , Pouligny Bernard , Dimova Rumiana , Sojic Nešo
Published: July 2007

We study the possibility of transfering a particle held in a far-field optical trap, namely the classical optical tweezers, to a near-field trap, in the form of a tapered metal tip (otherwise called an “apertureless probe”). The paper is theoretical: we compute the electromagnetic fields in both configurations, based on a vectorial nonparaxial representation of the Gaussian laser beam in the waist region. We afterwards use the coupled dipole method to compute the optical force acting on a spherical dielectric particle, in the 0.2−1μm range in diameter. We find that either repulsion or attraction of the particle by the metal probe is possible, depending on the beam polarization state, particle size, and curvature radius of the metal tip. Equilibrium states of the particle in contact with the tip, under illumination by the laser beam, are predicted.
High speed single photon detection in the near infrared
Authors: Yuan Z. L. , Kardynal B. E. , Sharpe A. W. , Shields A. J.
Published: July 2007

InGaAs avalanche photodiodes (APDs) are convenient for single photon detection in the near infrared (NIR) including the fiber communication bands (1.31∕1.55μm). However, to suppress afterpulse noise due to trapped avalanche charge, they must be gated with megahertz repetition frequencies, thereby severely limiting the count rate in NIR applications. Here, the authors show gating frequencies for InGaAs APDs well beyond 1GHz. Using a self-differencing technique to sense much weaker avalanches, the authors reduce drastically afterpulse noise. At 1.25GHz, they obtain a detection efficiency of 10.8% with an afterpulse probability of 6.16%. In addition, the detector features low jitter (55ps) and a count rate of 100MHz.
Fractal growth of nanocrystals in association with amorphous spinodal decomposition observed in an immiscible Hf-Nb system
Authors: Tai K. P. , Wang T. L. , Liu B. X.
Published: July 2007

Through an amorphous spinodal decomposition, dual metallic glasses are simultaneously formed in the Hf45Nb55 multilayered films upon 200keV xenon ion beam mixing at a dose of 2×1015Xe+∕cm2. Interestingly, further irradiation induced the growth of fractals in the major glass matrix and the fractals consisted of nanosized (around 20nm) polycrystals of bcc structure. The fractal dimension was determined by the image processor and found to increase from 1.70 to 1.84 within a dose range of (4–7)×1015Xe+∕cm2. The fractal growth in association with the amorphous spinodal decomposition is discussed in terms of atomic collision theory and cluster-diffusion-limited aggregation.
Excimer laser fabrication of microbumps on platinum thin films
Authors: Thanawala S. S. , Georgiev D. G. , Auner G. W.
Published: July 2007

In this letter we report conditions for the reproducible, laser fabrication of microbumps on platinum thin films deposited on borosilicate glass substrates. Microbumps are formed as a result of irradiation of platinum thin film surfaces by a single pulse of 248nm radiation from a KrF excimer laser. Atomic force microscopy and scanning electron microscopy in conjunction with energy dispersive x-ray analysis were used to characterize these microbumps. A simple qualitative view of the mechanism of microbump formation based on laser heating and movement of melted borosilicate glass and platinum materials is discussed.
Slow relaxation of spin reorientation following ultrafast optical excitation
Authors: Eimüller T. , Scholl A. , Ludescher B. , Schütz G. , Thiele J.-U.
Published: July 2007

The magnetization dynamic of a thermally driven spin reorientation transition is investigated in an optical pump–x-ray-probe imaging experiment with 100nm resolution. Excitation of a Fe∕Gd multilayer with a short laser pulse triggers a fast rotation of the magnetization out of the sample plane. Interestingly, relaxation back into the plane takes several nanoseconds, notedly longer than thermal relaxation.
Degradation of hole injection at the contact between a conducting polymer and a fluorene copolymer
Authors: Papadimitratos Alexios , Fong Hon Hang , Malliaras George G. , Yakimov Aharon , Duggal Anil
Published: July 2007

Hole injection was studied in devices that utilize the contact between poly[(ethylenedioxy)thiophene]/poly(styrenesulfonate) (PEDOT:PSS) and poly(9,9-dioctylfluorene-co-N,N’-bis(4-butylphenyl)-N,N’-diphenyl-1,4-phenylenediamine) (PFB). The transient space charge limited current injection technique was used to measure the hole mobility in the PFB layer and to estimate the hole injection efficiency at the contact. Prolonged electrical stressing of the devices did not affect hole mobility in PFB, while the injection efficiency decreased by an order of magnitude. These observations show that degradation occurs at the PEDOT:PSS/PFB contact, rather than the bulk of the PFB.
Resetting single nanoparticle structural phase with nanosecond pulses
Authors: Soares B. F. , MacDonald K. F. , Zheludev N. I.
Published: July 2007

The authors demonstrate that transitions from high temperature phases to low temperature phases in a gallium nanoparticle can be stimulated by nanosecond optical pulses, and explain how this phenomenon could be used in a single nanoparticle all-optical memory.
On the electric-dipole contribution to the valence-band offsets in semiconductor-oxide heterostructures
Authors: Mönch Winfried
Published: July 2007

The continua of interface-induced gap states (IFIGS) determine the band-structure lineup at semiconductor interfaces. Hence, both barrier heights of Schottky contacts and valence-band offsets in semiconductor heterostructures are composed of a zero-charge-transfer and an electric-dipole term. The analysis of experimental barrier heights and valence-band offsets yields IFIGS branch-point energies of 3.51±0.07eV for SiO2 and 2.98±0.26eV, 2.27±0.14, and 2.87±0.14eV for the high-κ oxides Al2O3, HfO2, and ZrO2, respectively. In the oxide heterostructures, the electric-dipole terms come up to 30% of the valence-band offsets and can thus not be neglected.
Formation and growth of SnO2 nanoparticles in silica glass by Sn implantation and annealing
Authors: Kuiri P. K. , Lenka H. P. , Ghatak J. , Sahu G. , Joseph B. , Mahapatra D. P.
Published: July 2007

Nanocrystalline Sn particles have been formed in silica glass through 50 keV Sn− implantation followed by annealing in N2 at 650 °C for 30 min. Samples prepared this way have been annealed in air for 1 h, separately at four different temperatures, 400, 600, 800, and 1000 °C, each at a given temperature. Annealing at temperatures higher than 400 °C has been found to result in oxidation of the Sn nanoparticles (NPs) and formation of the SnO2 phase as confirmed from optical absorption (OA), transmission electron microscopy, and Raman scattering measurements. For the sample annealed at 600 °C, Raman scattering data showed three bands at about 525, 629, and 771 cm−1, the last two corresponding to the A1g and B2g classical Raman modes of rutile SnO2. Increase in annealing temperature resulted in an increase in the intensities of the A1g and B2g modes showing better crystallinity. Also, the A1g peak shifted toward a higher wave number with a steady decrease in the intensity at 525 cm−1. This is in line with the growth in size of NPs as well as a reduction in the surface disorder. The Urbach tail width derived from the OA data also agrees with this.
Evolution of self-assembled InAs quantum ring formation
Authors: Ling Hong-Shi , Lee Chien-Ping
Published: July 2007

The evolution of InAs quantum ring (QR) formation and the corresponding optical properties were investigated by atomic force microscopy (AFM) and photoluminescence (PL) spectroscopy. Just like a nanoscale volcanic eruption, the transformation from quantum dots (QDs) to QRs using the capping and annealing process depends on how much InAs is removed from the center of the dots to the surrounding areas. The final structure was found to depend on the annealing temperature and the cap layer thickness. We have investigated the QR formation at different stages using various growth conditions. The findings provided a clear picture on the mechanism of ring formation. We were able to obtain QRs with various geometries by controlling these growth parameters.
Quantitative study of hydrogen-implantation-induced cavities in silicon by grazing incidence small angle x-ray scattering
Authors: Capello L. , Rieutord F. , Tauzin A. , Mazen F.
Published: July 2007

We used grazing-incidence small angle x-ray scattering to investigate properties of hydrogen implantation-induced platelets and cavities formed in silicon as a function of the implantation and annealing parameters. Density, orientation, and size (thickness and diameter) of these buried objects can be extracted from quantitative x-ray scattering intensity measurements, in a nondestructive manner. Detailed balance of hydrogen-induced defect evolution can be made with such data. Different defect populations result from different implantation temperatures and a low limit H dose is found for {111} platelets formation.
Preparation of aligned Ca3Co2O6 nanorods and their steplike magnetization
Authors: Li P. L. , Yao X. Y. , Gao F. , Zhao C. , Yin K. B. , Weng Y. Y. , Liu J.-M. , Ren Z. F.
Published: July 2007

Well-aligned Ca3Co2O6 nanorods (∼300nm in length and ∼40nm in diameter) on Si substrates are prepared by pulsed laser deposition. The steplike magnetization feature as identified in bulk Ca3Co2O6 can be retained in the nanorods in spite of the enhanced distortion of the magnetically ordered spin chains due to the finite size effect. The out-of-plane magnetization value is slightly larger than the in-plane value, which shows the small magnetic anisotropy. An additional distinct transition at 54K associated with the spin frustration is revealed, different from the bulk samples.
Third-order intermodulation in two-pole X-band HgBa2CaCu2O6+δ microstrip filters
Authors: Zhao Hua , Dizon Jonathan R. , Wu Judy Z.
Published: July 2007

Third-order intermodulation is studied in two-pole X-band high-temperature superconducting (HTS) HgBa2CaCu2O6+δ microstrip filters at >77K. The third-order intercept (IP3) of the HgBa2CaCu2O6+δ filters is consistently higher than that of the YBa2Cu3O7 filter of the same geometry in this temperature range. At 110K, the IP3 of 38dBm remains for the Hg-1212 filters, the best so far achieved at T>100K. The dc critical current density Jc and the rf one JIP3 derived from the IP3 have a similar reduced temperature dependence, suggesting that the magnetic vortex depinning in HTS materials dominates the microwave nonlinearity at elevated temperatures.
Microwave guiding and intense plasma generation at subcutoff dimensions for focused ion beams
Authors: Mathew Jose V. , Dey Indranuj , Bhattacharjee Sudeep
Published: July 2007

The mechanism of microwave guiding and plasma generation is investigated in a circular waveguide with a subcutoff dimension using pulsed microwaves of 3GHz. During the initial phase, gaseous breakdown is induced by the exponentially decaying wave. Upon breakdown, the refractive index of the plasma medium varies radially, with the plasma density reaching close to cutoff values in the central region. At lower pressures, the waves can propagate through the peripheral plasma with a reduced wavelength, due to the collisionally broadened upper hybrid resonance region. The intense narrow cross sectional plasma bears promise for multielemental focused ion beams.
Polarization-induced valence-band alignments at cation- and anion-polar InN∕GaN heterojunctions
Authors: Wu Chung-Lin , Lee Hong-Mao , Kuo Cheng-Tai , Gwo Shangjr , Hsu Chia-Hung
Published: July 2007

The authors show that the existence of polarization discontinuities at polar III-nitride heterointerfaces can lead to large core-level shifts of photoelectrons and modification of apparent valence-band offsets. In this letter, large Ga core-level shifts, resulting from the interface dipole fields, have been directly measured by photoelectron spectroscopy on In∕Ga-polar (0001)- and N-polar (0001¯)-oriented InN∕GaN heterojunctions with monolayer abrupt, nearly fully relaxed lattices. Combined with the photoelectron spectroscopic measurements of InN and GaN bulk epilayers, the determined valence-band offsets are 1.04 and 0.54eV for In∕Ga- and N-polar heterojunctions, respectively.
Fast electrical detection of Hg(II) ions with AlGaN∕GaN high electron mobility transistors
Authors: Wang Hung-Ta , Kang B. S. , Chancellor T. F. , Lele T. P. , Tseng Y. , Ren F. , Pearton S. J. , Johnson W. J. , Rajagopal P. , Roberts J. C. , Piner E. L. , Linthicum K. J.
Published: July 2007

Bare Au gated and thioglycolic acid functionalized Au-gated AlGaN∕GaN high electron mobility transistors (HEMTs) were used to detect mercury (II) ions. Fast detection of less than 5s was achieved for thioglycolic acid functionalized sensors. This is the shortest response time ever reported for mercury detection. Thioglycolic acid functionalized Au-gated AlGaN∕GaN HEMT based sensors showed 2.5 times larger response than bare Au-gated based sensors. The sensors were able to detect mercury (II) ion concentration as low as 10−7M. The sensors showed an excellent sensing selectivity of more than 100 for detecting mercury ions over sodium or magnesium ions. The dimensions of the active area of the sensor and the entire sensor chip are 50×50μm2 and 1×5mm2, respectively. Therefore, portable, fast response, and wireless based heavy metal ion detectors can be realized with AlGaN∕GaN HEMT based sensors.
Near-infrared intersubband absorption in nonpolar cubic GaN∕AlN superlattices
Authors: DeCuir E. A. , Fred E. , Manasreh M. O. , Schörmann J. , As D. J. , Lischka K.
Published: July 2007

Optical absorption spectra related to intersubband transitions in molecular beam epitaxially grown nonpolar cubic-GaN∕AlN superlattices were observed in the spectral range of 1.5–2.00μm. The background doping was measured using an electrochemical capacitance-voltage technique and found to be on the order of 1018cm−3. This doping level yields a Fermi energy level slightly above the ground state energy level enabling intersubband transitions to occur. The existence of the intersubband transition is verified in several samples with different well widths. The observed peak position energy of the intersubband transition is compared to those calculated using a transfer matrix method.
Improvement of charge storage characteristics on floating gated nonvolatile memory devices with In2O3 nanoparticles embedded polyimide gate insulator
Authors: Koo Hyun-Mo , Cho Won-Ju , Lee Dong Uk , Kim Seon Pil , Kim Eun Kyu
Published: July 2007

Nanofloating gate memory (NFGM) devices using In2O3 nanoparticles as charge storages embedded in polyimide gate insulator were fabricated. Self-assembled In2O3 nanoparticles were formed inside the polyimide matrix as a result of chemical reactions between indium ions and polymer precursors. The average diameter and the particle density were 7nm and 6×1011cm−2, respectively. The memory window of fabricated NFGM device due to the charging effect of In2O3 particles was larger than 4.4V. The charge storage characteristics of NFGM devices with In2O3 nanoparticles embedded in polyimide gate insulator were significantly improved by the postannealing in a 3% diluted hydrogen in N2 ambient.
Influence of electron injection on the temporal response of ZnO homojunction photodiodes
Authors: Lopatiuk-Tirpak O. , Nootz G. , Flitsiyan E. , Chernyak L. , Mandalapu L. J. , Yang Z. , Liu J. L. , Gartsman K. , Osinsky A.
Published: July 2007

The effects of solid-state electron injection on the peak amplitude and decay time of photosignal in a ZnO-based homojunction UV photodiode were studied using temporal photoresponse measurements under femtosecond pulses of 355nm radiation. The injection of about 50C of charge, carried out by applying forward bias to the junction, resulted in a nearly twofold increase of the peak photoresponse and a corresponding increase of the decay constant. Both observations are shown to be a consequence of electron trapping. The long-term stability of the induced changes is also discussed.
Dielectric functions and electronic structure of InAsxP1−x films on InP
Authors: Choi S. G. , Palmstrøm C. J. , Kim Y. D. , Aspnes D. E. , Kim H. J. , Chang Yia-Chung
Published: July 2007

The authors present room-temperature pseudodielectric function spectra ⟨ε⟩ of InAsxP1−x films grown on (001) InP by chemical beam epitaxy. A wet-chemical etching procedure was used to remove overlayers and obtain the best approximation to the bulk dielectric responses ε of the films. By line shape fitting, we determine the compositional dependences of the E1, E1+Δ1, E0′, E2, and E2′ critical-point energies. The results are in good agreement with calculations of the electronic structure done by the linear augmented Slater-type orbital method.
The Center for Lifespan Psychology at the Max Planck Institute for Human Development: Overview of conceptual agenda and illustration of research activities
Authors: Lindenberger Ulman , Li Shu‐Chen , Lövdén Martin , Schmiedek Florian
Published: July 2007

Founded in 1981 by the late Paul B. Baltes, the Center for Lifespan Psychology at the Max Planck Institute for Human Development has helped to establish lifespan psychology as a distinct conceptual approach within developmental psychology. Recently, the Center has extended its research programme into developmental behavioural neuroscience. Here, we provide an overview of the Center's conceptual agenda, and present two of its seven research projects in greater detail. Work at the Center is guided by three propositions: (1) to study lifespan changes in behaviour as interactions among maturation, learning, and senescence; (2) to develop theories and methods that integrate empirical evidence across domains of functioning, timescales, as well as behavioural and neuronal levels of analysis; (3) to identify mechanisms of development by exploring age‐graded differences in plasticity. The Intra‐Person Dynamics Project studies the organization of cognitive abilities within individuals of different ages, and investigates lifespan age differences in the plasticity and components of episodic memory performance. The Sensorimotor–Cognitive Couplings Project examines lifespan differences in dynamic dependencies between sensorimotor and cognitive performance. Both projects combine behavioural assessments with methods from developmental neuroscience to delineate age‐graded changes in brain–behaviour mappings. Current research in other projects includes: (1) behavioural development in very old age, as assessed in the Berlin Aging Study; (2) the interplay of motivation, affect, and cognition in developmental regulation; (3) behavioural and electrophysiological mechanisms of social interaction from infancy to adulthood; and (4) formal and statistical issues in structural equation modelling, with an emphasis on latent growth curve modelling. Graduate education and research at the Center profit greatly from cooperation with other institutions in Berlin and Potsdam as well as from national and international collaboration.
Acrosomal exocytosis, a special type of regulated secretion
Authors: Mayorga Luis S. , Tomes Claudia N. , Belmonte Silvia A.
Published: July 2007

The acrosome is a single secretory granule present in the head of mammalian ‐ and other animal groups ‐ sperm. Secretion of this granule is an absolute requirement for physiological fertilization. Acrosome exocytosis is a synchronized and tightly regulated all‐or‐nothing process, with no recycling of membranes. In the last few years, it has been shown that acrosomal exocytosis is mediated by a molecular mechanism that is homologous to that reported in the secretion of neuroendocrinal cells. Moreover, because of its particular characteristics, acrosomal exocytosis is a unique mammalian model for the study of the different steps of the membrane fusion cascade. Combining results in intact and permeabilized sperm, the following sequence of events has been proposed. In resting sperm, SNARE proteins are locked in inactive cis complexes. Sperm activation causes a calcium increase in the cytoplasm that promotes the production of cAMP and activates Rab3A. Afterwards, NSF and αSNAP disassemble cis complexes and the free SNAREs are then able to reassemble in loose trans complexes. Membrane fusion is arrested at this stage until calcium is released from inside the acrosome by inositol 1,4,5‐trisphosphate‐sensitive calcium channels to trigger the final steps of membrane fusion, which require fully assembled trans SNARE complexes and the calcium sensor synaptotagmin. This working model is still incomplete and tentative. Its improvement will be important to share light on this and other processes of regulated exocytosis. Moreover, it will bring new perspectives into the field of sperm‐related fertility and sterility.
IUBMB Life, 59: 286‐292, 2007
The carbonate radical and related oxidants derived from bicarbonate buffer
Authors: Medinas Danilo B. , Cerchiaro Giselle , Trindade Daniel F. , Augusto Ohara
Published: July 2007

The unequivocal demonstration that the carbonate radical (CO3 •‐) is produced from the reaction between the ubiquitous carbon dioxide and peroxynitrite, renewed the interest in the pathogenic roles of oxidants derived from the main physiological buffer, the bicarbonate‐carbon dioxide pair. Here, we review the biochemical properties of both the carbonate radical and peroxymonocarbonate (HCO4 ‐), and discuss the evidence of their formation under physiological conditions. Overall, the review emphasizes the recognition of the biological relevance of oxidants derived from the main physiological buffer as a crucial step into the understanding and control of numerous pathological states. IUBMB Life, 59: 1 ‐ 8, 2007
IUBMB Life, 59: 255‐262, 2007
DDT, pyrethrins, pyrethroids and insect sodium channels
Authors: Davies T. G. E. , Field L. M. , Usherwood P. N. R. , Williamson M. S.
Published: July 2007

The long term use of many insecticides is continually threatened by the ability of insects to evolve resistance mechanisms that render the chemicals ineffective. Such resistance poses a serious threat to insect pest control both in the UK and worldwide. Resistance may result from either an increase in the ability of the insect to detoxify the insecticide or by changes in the target protein with which the insecticide interacts. DDT, the pyrethrins and the synthetic pyrethroids (the latter currently accounting for around 17% of the world insecticide market), act on the voltage‐gated sodium channel proteins found in insect nerve cell membranes. The correct functioning of these channels is essential for normal transmission of nerve impulses and this process is disrupted by binding of the insecticides, leading to paralysis and eventual death. Some insect pest populations have evolved modifications of the sodium channel protein which prevent the binding of the insecticide and result in the insect developing resistance. Here we review some of the work (done at Rothamsted Research and elsewhere) that has led to the identification of specific residues on the sodium channel that may constitute the DDT and pyrethroid binding sites.
IUBMB Life, 59: 151‐162, 2007
Redundancy Analysis and a Distributed Self-Organization Protocol for Fault-Tolerant Wireless Sensor Networks
Authors: Zou Yi , Chakrabarty Krishnendu
Published: July 2007

Sensor nodes in a distributed sensor network can fail due to a variety of reasons, e.g., harsh environmental conditions, sabotage, battery failure, and component wear-out. Since many wireless sensor networks are intended to operate in an unattended manner after deployment, failing nodes cannot be replaced or repaired during field operation. Therefore, by designing the network to be fault-tolerant, we can ensure that a wireless sensor network can perform its surveillance and tracking tasks even when some nodes in the network fail. In this paper, we describe a fault-tolerant self-organization scheme that designates a set of backup nodes to replace failed nodes and maintain a backbone for coverage and communication. The proposed scheme does not require a centralized server for monitoring node failures and for designating backup nodes to replace failed nodes. It operates in a fully distributed manner and it requires only localized communication. This scheme has been implemented on top of an energy-efficient self-organization technique for sensor networks. The proposed fault-tolerance-node selection procedure can tolerate a large number of node failures using only localized communication, without losing either sensing coverage or communication connectivity.
Architecture of Wireless Sensor Networks with Mobile Sinks: Multiple Access Case
Authors: Song Liang , Hatzinakos Dimitrios
Published: July 2007

We propose to develop Wireless Sensor Networks with Mobile Sinks (MSSN), under high sensor node density, where multiple sensor nodes need to share one single communication channel in the node-to-sink transmission. By exploiting the tradeoff between the successful information retrieval probability and the nodes energy consumption, a number of multiple nodes transmission scheduling algorithms are proposed. Both optimal and suboptimal algorithms, which exhibit exponential and linear complexity respectively, are discussed under the desired application. Computer simulations show that suboptimal algorithms perform nearly as good as the optimal one. The study leads to the cross-layer Wireless Link layer design for MSSN.
Women, the embodiment of health and carceral space
Authors: Robert Dominique , Frigon Sylvie , Balzile Renée
Published: July 2007

Using the example of women incarcerated in Canada, this paper aims at showing the necessity of studying prisoners’ health and healthcare through a perspective informed both by a criminology of the body and prison/penal sociology. Health is too often constructed as a set of discrete variables that can be isolated from the whole person and her environment. In this paper, we want to show the complexities and richness of situating carceral health and healthcare within the experience of the body and prison. After describing the situation of women in prison in Canada and their health status before incarceration and while in prison, the intricacies of health, healthcare and punishment will be described and we will conclude by showing how health and the body act as a site of control and a site of resistance for incarcerated women.
Suicide prevention in correctional institutions: The significance of solitary cell accommodation
Authors: Frottier Patrick , König Franz , Matschnig Teresa , Seyringer Michaele‐Elena , Frühwald Stefan
Published: July 2007

The decision whether admitted inmates should be placed in solitary cells or shared cells has to take place immediately after intake. This decision can have major impact on the occurrence of suicide in custody. The ‘Viennese Instrument for Suicidality in Correctional Institutions’ presented here is based on the results of a case‐control study examining suicide prevention in general and within the prison population in particular. The administration of this instrument helps the officers to decide about the accommodation without an immediate psychiatric or psychological assessment. The screening of newly admitted offenders to prison for suicidality is necessary to better estimate the suicide risk.
Effect of dronedarone on renal function in healthy subjects
Authors: Tschuppert Yvonne , Buclin Thierry , Rothuizen Laura E. , Decosterd Laurent A. , Galleyrand Jacques , Gaud Christine , Biollaz Jérôme
Published: July 2007

What is already known about this subject

• Creatinine clearance (CL) is used to assess glomerular filtration rate (GFR). However, it is known to slightly overestimate the true GFR, due to renal tubular secretion of creatinine.

• During phase I‐III clinical trials, a 10–15% increase in serum creatinine has been observed both in healthy subjects and patients receiving the new antiarrhythmic agent dronedarone.

What this study adds

• Dronedarone affects the renal handling of creatinine and N‐methylnicotinamide, two cations, while leaving unchanged GFR, assessed through sinistrin CL, and renal plasma flow and anion secretion, assessed through para‐amino‐hippurate CL.

• This suggests a specific action of dronedarone on renal organic cation transport explaining the limited, reversible effect of dronedarone on serum creatinine, which must not be interpreted as reflecting an impairment of renal function, but which may indicate an interaction potential with cationic drugs.

Aims

To assess the effects of dronedarone on renal function and tubular cation handling.

Methods

Twelve healthy males were enrolled in a randomized, cross‐over, placebo‐controlled, double‐blind study. They received 400 mg dronedarone or placebo twice daily for 7 days. Baseline and on‐treatment renal function tests were performed under strict standardization of intakes, by assessing creatinine, sinistrin, para‐amino‐hippurate (PAH) and N‐methylnicotinamide (NMN) CLs, and electrolyte excretion.

Results

Compared with placebo, dronedarone significantly decreased renal creatinine CL (mean 138–119 ml min−1 after dronedarone vs. 142–149 ml min−1 after placebo) and NMN CL (448–368 ml min−1vs. 435–430 ml min−1), but did not alter renal sinistrin CL, PAH CL and other renal parameters.

Conclusions

Dronedarone reduces renal creatinine and NMN clearance by about 18%, without evidence of an effect on GFR, renal plasma flow or electrolyte exchanges. This suggests a specific partial inhibition of tubular organic cation transporters (OCT). A limited increase in serum creatinine is therefore expected with dronedarone treatment, but does not mean there is a decline in renal function.
FLT3 inhibition in acute myeloid leukaemia
Authors: Knapper Steven
Published: July 2007

FMS‐like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase that appears to play a significant role in leukaemogenesis. Activating mutations of FLT3 are present in approximately one‐third of acute myeloid leukaemia patients and are associated with adverse clinical outcome, while many non‐mutated cases also show evidence of FLT3 activation. FLT3 thus represents a potentially exciting molecular therapeutic target. A number of small‐molecule tyrosine kinase inhibitors with anti‐FLT3 activity have been developed and several of these compounds have entered early phase clinical trials where clinical anti‐leukaemic activity has been demonstrated. The depth and duration of clinical responses to FLT3 inhibitor monotherapy have been modest, however, and a number of mechanisms by which blasts may acquire resistance have been proposed. Based on preclinical evidence of synergy with conventional chemotherapy, several combination trials are now underway. FLT3 inhibition may also be effective used in combination with other molecularly targeted agents, in postchemotherapy stem‐cell‐directed maintenance therapy and in MLL‐rearranged infant acute lymphoblastic leukaemia.
Lack of synchrony among multiple nuclei induces partial DNA fragmentation in V79 cells polyploidized by demecolcine
Authors: Fujikawa‐Yamamoto K. , Ohdoi C. , Yamagishi H. , Zong Z. ‐p. , Murakami M. , Yamaguchi N.
Published: July 2007

Abstract. The nuclear morphology of polyploidized cells was examined in V79 Chinese hamster cells polyploidized by demecolcine or K‐252a, inhibitors of spindle fibre formation and protein kinases, respectively. A variety of nuclear morphologies, including multinuclei, were observed in V79 cells polyploidized by demecolcine but not by K‐252a, which produced mononuclear cells. A lack of synchrony in the nuclear cycle was observed among nuclei in multinuclear polyploidized cells. Partial DNA fragmentation, defined as DNA fragmentation of a nucleus in a multinuclear cell, was detected using the TUNEL method in V79 cells polyploidized by demecolcine but not by K‐252a. Apoptosis occurred earlier in cell populations treated with demecolcine than in these treated with K‐252a once the drugs were removed from the medium, suggesting that polyploidized cells with separate nuclei tend to apoptose earlier than those with mononuclei.
A simple model of the eco‐hydrodynamics of the epilimnion of Lake Tanganyika
Authors: NAITHANI JAYA , PLISNIER PIERRE‐DENIS , DELEERSNIJDER ERIC
Published: July 2007

1. The ecosystem response of Lake Tanganyika was studied using a four‐component, nutrient–phytoplankton–zooplankton–detritus, phosphorus‐based ecosystem model coupled to a nonlinear, reduced‐gravity, circulation model. The ecosystem model, an improved version of the earlier eco‐hydrodynamics model developed for Lake Tanganyika, was used to estimate the annual primary production of Lake Tanganyika and its spatial and temporal variability. The simulations were driven with the National Centres for Environmental Protection (NCEP) records for winds and solar radiation forcing.

2. The simulated annual cycles of the four ecosystem variables and the daily net primary production were compared with the observations. The comparison showed that simulations reproduced realistically the general features of the annual cycles of epilimnial phosphate, net primary production and plankton dynamics.

3. The climatic simulations for the years 1970–2006 yielded a daily averaged integrated upper layer net production ranging from 0.11 to 1.78 g C m−2 day−1and daily averaged chlorophyll‐a(chl‐a) from 0.16 to 4.3 mg m−3. Although the nutrient concentrations in the epilimnion during the strong wind years were high, the net production was low, which is partly because of the greater vertical mixing, produced by strong winds, exposing the phytoplankton to low light conditions in deeper waters. The simulated annual net production and chl‐aagreed quite well with observed production available in the literature.

4. We envisage using this model to predict the future scenarios of primary productivity in the lake.
Chk2 kinase is required for methylglyoxal‐induced G2/M cell‐cycle checkpoint arrest: implication of cell‐cycle checkpoint regulation in diabetic oxidative stress signaling
Authors: Kani Shuichi , Nakayama Emiko , Yoda Akinori , Onishi Nobuyuki , Sougawa Nagako , Hazaka Yuki , Umeda Tsuyoshi , Takeda Kohsuke , Ichijo Hidenori , Hamada Yasuhiro , Minami Yasuhiro
Published: July 2007

Methylglyoxal (MG) is a reactive endogenous metabolite that is produced from the process of degradation of triose‐phosphates. Under hyperglycemic conditions the rate of MG formation increases as a result of elevated concentrations of precursors. It has been established that MG elicits oxidative stress signaling, leading to the activation of MAP kinases, p38 MAPK and JNK, yet it remains largely unknown about a role of cell‐cycle checkpoint regulation in MG‐induced signaling. Here, we show that checkpoint kinases, Chk1 and Chk2, as well as their upstream ATM kinase are phosphorylated and activated following MG treatment of cultured cells. This MG‐induced activation of Chk1 and Chk2 were inhibited by either aminoguanidine (AG), an inhibitor of production of advanced glycation end products (AGEs) or N‐acetyl‐l‐cysteine (NAC), an anti‐oxidant in dose dependent manners, indicating that oxidative stress via AGEs is involved critically in the activation of Chk1 and Chk2 by MG. Furthermore, it was found that cell‐cycle synchronized cells exhibited G2/M checkpoint arrest following MG treatment, and that siRNA‐mediated knock‐down of Chk2, but not Chk1, results in a failure of MG‐induced G2/M arrest. Thus, the results indicate a critical role for Chk2 in MG‐induced G2/M cell‐cycle checkpoint arrest.
Interaction between two glaucoma genes, optineurin and myocilin
Authors: Park Bum‐Chan , Tibudan Martin , Samaraweera Mishan , Shen Xiang , Yue Beatrice Y.J.T.
Published: July 2007

Myocilin (MYOC) and optineurin (OPTN) are two genes linked to glaucoma, a major blinding disease. To investigate the possible molecular interactions between MYOC and OPTN genes, we over‐expressed MYOC and examined its effect on the level of endogenous OPTN in human trabecular meshwork (TM) cells and vice versa. We noted that over‐expressing MYOC did not affect the OPTN level, whereas OPTN over‐expression induced an up‐regulation of the endogenous MYOC. This induction was also observed in other ocular and non‐ocular cell types including PC12 cells. The endogenous levels of both OPTN and MYOC genes were in addition found increased when PC12 cells underwent differentiation upon treatment with nerve growth factor (NGF). Over‐expression of OPTN resulted in prolonged turnover rate of MYOC mRNA but had little effect on the promoter activity of the MYOC gene. The over‐expressed OPTN was localized in the cytoplasm, not translocated into the nucleus. These results indicate that interaction exists between OPTN and MYOC genes. Regulation of MYOC expression by OPTN is achieved primarily through control of the mRNA stability.
The zinc finger repressor, ZBP‐89, recruits histone deacetylase 1 to repress vimentin gene expression
Authors: Wu Yongzhong , Zhang Xueping , Salmon Morgan , Zehner Zendra E.
Published: July 2007

Vimentin, a member of the intermediate filament (IF) protein family, exhibits a complex pattern of tissue‐ and developmental‐specific expression. Although vimentin is widely expressed in the embryo, its expression becomes restricted during terminal differentiation. Moreover, it is often expressed in tissue culture cells despite their embryological origin and is a marker for the metastatic tumor cell. Previously, the vimentin promoter has been shown to contain several positive‐ and negative‐acting cis‐elements. The negative elements bind the transcription factor ZBP‐89. Interestingly, ZBP‐89 can be either an activator or a repressor of gene expression. For instance, ZBP‐89 has been shown to activate p21waf1/cip1 expression by recruiting p300 to the p21 promoter. Here, we have investigated the mechanism of ZBP‐89 repression. The histone deacetylase (HDAC) inhibitor TSA enhances vimentin gene expression requiring the proximal promoter region including GC‐box 1, a known Sp1/Sp3 binding site. Chromatin immunoprecipitation (ChIP) assays document an increase in the acetylation status of histone H3 on the endogenous vimentin gene concomitant with TSA treatment. However, EMSAs, DNA precipitation, co‐immunoprecipitation and ChIP data show that it is not Sp1, but rather ZBP‐89, which recruits HDAC1. From these studies we conclude that ZBP‐89 functions as a repressor by recruiting HDAC1 to the vimentin promoter.