bluuebunny/crossref_metadata_2025 huggingface dataset:
Room temperature single electron charging in single silicon nanochains
Authors: Rafiq M. A. , Durrani Z. A. K. , Mizuta H. , Colli A. , Servati P. , Ferrari A. C. , Milne W. I. , Oda S.
Published: March 2008

Single-electron charging effects are observed at room temperature in single Si nanochains. The nanochains, grown by thermal evaporation of SiO solid sources, consist of a series of Si nanocrystals ∼10nm in diameter, separated by SiO2 regions. Multiple step Coulomb staircase current-voltage characteristics are observed at 300K in devices using single, selected, nanochains. The characteristics are investigated using a model where the nanochain forms a multiple tunnel junction. The single-electron charging energy for a nanocrystal within the multiple-tunnel junction is EC=e2∕2Ceff∼0.32eV, ∼12kBT at 300K.
Image reconstruction for multiphoton fluorescence microscopy
Authors: Mondal Partha Pratim , Vicidomini Giuseppe , Diaspro Alberto
Published: March 2008

We present a general image reconstruction methodology for multiphoton fluorescence microscopy. The method is primarily based on Markov random field modeling of the detected image data. Evaluation on two-photon-excitation-(TPE) and two-photon-excited-4PI-microscopy images shows high quality artifact-free reconstruction. Image reconstruction for multiphoton imaging modalities such as TPE and 4PI may find potential application in nano-bioimaging and optical imaging.
X-ray investigation of subsurface interstitial oxygen at Nb/oxide interfaces
Authors: Delheusy M. , Stierle A. , Kasper N. , Kurta R. P. , Vlad A. , Dosch H. , Antoine C. , Resta A. , Lundgren E. , Andersen J.
Published: March 2008

We have investigated the dissolution of a natural oxide layer on a Nb(110) surface upon heating, combining x-ray reflectivity, grazing incidence diffuse scattering, and core-level spectroscopy. The natural oxide reduces after heating to 145°C partially from Nb2O5 to NbO2, and an enrichment in subsurface interstitial oxygen by ∼70% in a depth of 100Å is observed. After heating to 300°C, the oxide reduces to NbO and the surplus subsurface oxygen gets dissolved into the bulk. Our approach can be applied for further investigation of the effect of subsurface interstitial oxygen on the performance of niobium rf cavities.
Acoustic-counterflow microfluidics by surface acoustic waves
Authors: Cecchini Marco , Girardo Salvatore , Pisignano Dario , Cingolani Roberto , Beltram Fabio
Published: March 2008

In this letter, we demonstrate an unexpected surface-acoustic-wave (SAW)-driven pumping effect in hydrophobic polydimethilsiloxane (PDMS)-lithium niobate (LiNbO3) microchannels. Atomization within the fluidic channel followed by SAW-assisted coalescence leads to liquid counterflow with respect to the SAW propagation direction. This physical mechanism is contrasted with the acoustic-streaming process driving isolated drop displacement on piezoelectric substrates. This principle is shown not to be readily applicable to the present microchannel case. The proposed device geometry can be exploited to integrate micropumps into complex microfluidic chips, improving the portability of micro-total-analysis systems.
Retarding field analyzer for ion energy distribution measurements at a radio-frequency biased electrode
Authors: Gahan D. , Dolinaj B. , Hopkins M. B.
Published: March 2008

A retarding field energy analyzer designed to measure ion energy distributions impacting a radio-frequency biased electrode in a plasma discharge is examined. The analyzer is compact so that the need for differential pumping is avoided. The analyzer is designed to sit on the electrode surface, in place of the substrate, and the signal cables are fed out through the reactor side port. This prevents the need for modifications to the rf electrode—as is normally the case for analyzers built into such electrodes. The capabilities of the analyzer are demonstrated through experiments with various electrode bias conditions in an inductively coupled plasma reactor. The electrode is initially grounded and the measured distributions are validated with the Langmuir probe measurements of the plasma potential. Ion energy distributions are then given for various rf bias voltage levels, discharge pressures, rf bias frequencies—500kHzto30MHz, and rf bias waveforms—sinusoidal, square, and dual frequency.
A multiplexed fiber Bragg grating sensor for simultaneous salinity and temperature measurement
Authors: Men Liqiu , Lu Ping , Chen Qiying
Published: March 2008

An in-line one-fiber approach to realize simultaneous measurement of salinity and temperature is proposed. The sensor system, which consists of multiplexed polymer-coated fiber Bragg gratings, showed that the polyimide-coated grating responds to variations of both temperature and salinity, while the acrylate-coated grating is only sensitive to the environmental temperature. The experimental results indicated that the temperature sensitivity of the acrylate-coated grating in water was 0.0102nm∕°C for redshifted Bragg wavelength with increasing temperature, and the temperature and the salinity sensitivities of the polyimide-coated grating were 0.0094nm∕°C (redshifted) and 0.0165nm∕M (blueshifted), respectively, which are in excellent agreement with the theoretical analysis.
Branched SnO2 nanowires on metallic nanowire backbones for ethanol sensors application
Authors: Wan Qing , Huang Jin , Xie Zhong , Wang Taihong , Dattoli Eric N. , Lu Wei
Published: March 2008

We report the synthesis of hierarchically branched semiconducting SnO2 nanowire on metallic Sb-doped SnO2 nanowires by the sequential seeding of multiple nanowire generations with Au nanoparticles as catalysts. Such semiconducting nanowire/metallic backbone complex structures increase the potential functionality of SnO2 nanowires. Branched SnO2 nanowire films are used as sensing materials for high-performance ethanol sensor fabrication. The nanowire sensors show sub-ppm sensitivity and fast response and recovery times at 300°C. A linear equation relationship between sensitivity and the ethanol vapor concentration was observed.
Tunable work functions of platinum gate electrode on HfO2 thin films for metal-oxide-semiconductor devices
Authors: Kim Yong-Mu , Lee Jang-Sik
Published: March 2008

The change in work function of a platinum gate electrode on a HfO2 dielectric layer was examined as a function of the annealing conditions and thickness of the HfO2 layers. HfO2 thin films with a platinum gate electrode were deposited at various thicknesses to form metal-oxide-semiconductor capacitors. An analysis of the capacitance-voltage responses, equivalent oxide thickness, and flatband voltage variations revealed effective work functions of the platinum gate electrode ranging from 4.24to4.98eV. This result will provide guidelines for process-dependent metal work function modulation and integration of high-k dielectric/metal gate stacks.
Stable freestanding thin films of pure water
Authors: Weon B. M. , Je J. H. , Hwu Y. , Margaritondo G.
Published: March 2008

Obtaining water microstructures is very difficult because of low viscosity and high surface tension. We produced stable freestanding thin films of pure water by x-ray bombardment of small liquid volumes in capillary tubes. A detailed characterization with phase-contrast radiology demonstrated a lifetime beyond 1h with no chemical stabilizer for micron-thickness films with half-millimeter-level diameter. This can be attributed to the interplay of two x-ray effects: water evaporation and surface charging.
Intense terahertz emission from a-plane InN surface
Authors: Ahn H. , Ku Y.-P. , Chuang C.-H. , Pan C.-L. , Lin H.-W. , Hong Y.-L. , Gwo S.
Published: March 2008

We report a significant enhancement in terahertz emission from the indium nitride (InN) films grown along the a axis (a-plane InN), relative to the InN films grown along the c axis. The primary radiation mechanism of the a-plane InN film is found to be due to the acceleration of photoexcited carriers under the polarization-induced in-plane electric field perpendicular to the a axis, which effectively enhances the geometrical coupling of the radiation out of semiconductor. In addition, azimuthal angle dependence measurement shows that the p-polarized terahertz output consists of a large angularly independent component and a weak component with a distinctive fourfold rotation symmetry.
Fabrication and characterization of a nanoelectromechanical switch with 15-nm-thick suspension air gap
Authors: Jang Weon Wi , Lee Jeong Oen , Yoon Jun-Bo , Kim Min-Sang , Lee Ji-Myoung , Kim Sung-Min , Cho Keun-Hwi , Kim Dong-Won , Park Donggun , Lee Won-Seong
Published: March 2008

We developed titanium nitride (TiN) based nanoelectromechanical (NEM) switch with the smallest suspension air-gap thickness ever made to date by a “top-down” complementary metal-oxide semiconductor fabrication methods. Cantilever-type NEM switch with a 15-nm-thick suspension air gap and a 35-nm-thick TiN beam was successfully fabricated and characterized. The fabricated cantilever-type NEM switch showed an essentially zero off current, an abrupt switching with less than 3mV/decade, and an on/off current ratio exceeding 105 in air ambient. Also achieved was an endurance of over several hundreds of switching cycles under dc and ac biases in air ambient.
Volume dependence of the magnetic coupling in LaFe13−xSix based compounds
Authors: Jia L. , Sun J. R. , Wang F. W. , Zhao T. Y. , Zhang H. W. , Shen B. G. , Li D. X. , Nimori S. , Ren Y. , Zeng Q. S.
Published: March 2008

The effects of pressure and hydrogenation, the former causes a lattice contraction while the latter causes an expansion of the sample, have been systematically studied for LaFe13−xSix (x=1.3–2.1). It is found that the typical change of the Curie temperature is ∼150K when ∼1.6H∕f.u. is absorbed and ∼−106K as the pressure sweeps from 0to1GPa. One of the most remarkable results of the present work is the presence of a universal relation between Curie temperature and phase volume. The former linearly grows with the increase of lattice constant (∼1510K∕Å), irrespective of how the phase volume is modified. This result implies the exclusive dependence of the magnetic coupling in LaFe13−xSix on the Fe–Fe distances and the interstitial hydrogen does not affect the electronic structure of the compounds.
Effect of hot-carrier-induced interface states distribution on linear drain current degradation in 0.35μm n-type lateral diffused metal-oxide-semiconductor transistors
Authors: Lee J. R. , Chen Jone F. , Wu Kuo-Ming , Liu C. M. , Hsu S. L.
Published: March 2008

The mechanisms of hot-carrier-induced linear drain current (Idlin) degradation in a 0.35μm n-type lateral diffused metal-oxide-semiconductor transistor, operating at a nominal voltage of 12V, is investigated. Results and analysis show that the location of hot-carrier-induced interface states varies with stress gate voltage. Stress-induced interface states located in accumulation region under polygate have little effect on Idlin degradation. As a result, interface states located in drain-side spacer region dominate Idlin degradation when interface states located in channel region are negligible.
Room temperature continuous wave operation of quantum cascade lasers with watt-level optical power
Authors: Bai Y. , Darvish S. R. , Slivken S. , Zhang W. , Evans A. , Nguyen J. , Razeghi M.
Published: March 2008

We demonstrate quantum cascade lasers at an emitting wavelength of 4.6μm, which are capable of room temperature, high power continuous wave (cw) operation. Buried ridge geometry with a width of 9.8μm was utilized. A device with a 3mm cavity length that was epilayer-down bonded on a diamond submount exhibited a maximum output power of 1.3W at room temperature in cw operation. The maximum output power at 80K was measured to be 4W, with a wall plug efficiency of 27%.
Radial vibration mode of 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 single crystal and its applications
Authors: Wang Feifei , Zhou Dan , Luo Laihui , Zhao Xiangyong , Luo Haosu , Zhang Yuanwei , Wu Jun , Zhu Hua
Published: March 2008

Ferroelectric single crystal (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 (PMNT) has attracted considerable attention for its outstanding piezoelectric properties after poled along the ⟨001⟩ or ⟨101⟩ directions and it is being actively applied to various ultrasonic devices. However, almost all previous applications focus on the longitudinal extension, transverse extension, thickness extension and thickness shear vibration mode. Here, we investigated the radial vibration mode of the ⟨001⟩ poled 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 single crystal. Both the finite element simulation and experimental results have shown that the performance of radial vibration mode is excellent. The coupling coefficient of radial vibration mode can reach 0.84 and the anisotropy of the circular plate is very weak after it was poled along the ⟨001⟩ direction. Based on this mode, we further designed and fabricated a disk-type piezoelectric transformer and the open circuit voltage step-up ratio reached about 50 with no spurious vibration mode around the resonance frequency. All these have shown that the radial vibration mode of PMNT single crystal is also promising and useful for other piezoelectric device applications.
Rapid crystallization of GeTe–Bi2Te3 mixed layer
Authors: Lee Tae-Yon , Kim Cheolkyu , Kang Younseon , Suh Dong-Seok , Kim Kijoon H. P. , Khang Yoonho
Published: March 2008

We report rapid crystallization of GeTe–Bi2Te3 mixed layers. The as-deposited (GeTe)1−x(Bi2Te3)x (GBT) layers with x>0.5 are fcc crystalline, while the layers with x<0.5 are amorphous, for cosputter deposition at room temperature. We found that Bi2Te3 significantly enhances the crystallization of the GBT layers. Furthermore, both temperature and minimum time required for crystallization (Tc and tc,min) of GBT layers are smaller than those of (GeTe)1−x(Sb2Te3)x (GST) layers. For example, crystallization of GBT layer with x=0.12 occurs at 155.0°C within 30.9ns, which is around 1∕3 of 95.7ns for Ge2Sb2Te5 with Tc=168.5°C.
Boron’s effect on martensitic transformation and magnetocaloric effect in Ni43Mn46Sn11Bx alloys
Authors: Xuan H. C. , Wang D. H. , Zhang C. L. , Han Z. D. , Gu B. X. , Du Y. W.
Published: March 2008

The most used method for changing the martensitic transformation temperatures in the ferromagnetic shape memory alloys is tuning the valence election concentration e∕a. In this paper, we report an alternative way, i.e., introducing few interstitial boron atoms in Ni43Mn46Sn11 alloy. The experimental results show that the martensitic transformation temperatures increase with the increasing boron content remarkably and large magnetic entropy changes can be obtained in these alloys. A possible origin of the enhanced martensitic transformation temperatures and large magnetic entropy changes is discussed in this paper.
Tunable transmission spectra of acoustic waves through double phononic crystal slabs
Authors: Liu Fengming , Cai Feiyan , Ding Yiqun , Liu Zhengyou
Published: March 2008

Acoustic resonant modes in a slab with a periodic array of holes are analyzed by using three-dimensional finite-difference time-domain method. We show that there exist two different types of resonant modes in this slab: the coupled Stoneley wave resonant modes and the waveguide resonant modes. Both resonant modes can lead to complex resonant line shapes in the transmission spectrum. By using the distinct property of these resonant modes, a tunable phononic crystal structure consisting of coupled phononic crystal slabs is introduced for achieving acoustic filters and sensors.
Influence of crystalline quality of low-temperature GaN cap layer on current collapse in AlGaN∕GaN heterostructure field-effect transistors
Authors: Waki E. , Deguchi T. , Nakagawa A. , Egawa T.
Published: March 2008

The correlation between the crystalline quality of low-temperature GaN (LT-GaN) films and current collapse in AlGaN∕GaN heterostructure field-effect transistors with a LT-GaN cap layer was investigated. LT-GaN cap layers were grown at various temperatures ranging from 450to700°C. No current collapse was observed for heterostructure field-effect transistors with LT-GaN cap layers grown at 500 and 550°C. The crystalline quality of the 1-μm-thick LT-GaN films grown at 450–700°C was then studied through x-ray diffraction and selected area electron diffraction measurements. The crystalline quality, considered by measuring the full width at half maximum through x-ray diffraction, deteriorated as the growth temperature decreased. The crystal structure of LT-GaN films grown at 500 and 550°C was confirmed as polycrystalline. Thus, the results demonstrated that in AlGaN∕GaN heterostructure field-effect transistors, a polycrystalline structure provides the most effective LT-GaN cap layer for suppressing current collapse.
Studies of competition between Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock) and native pastures. 2. Seedling responses
Authors: Badgery W. B. , Kemp D. R. , Michalk D. L. , King W. McG.
Published: March 2008

Native perennial grass competition can substantially reduce the invasion of Nassella trichotoma (serrated tussock), a major perennial grass weed problem in south-eastern Australia. This paper reports on a field experiment that investigated the recruitment of N. trichotoma seedlings, and determined what level of native grass competition was needed to prevent establishment in the central-west of NSW. Grasslands that maintained >2 t dry matter (DM)/ha and 100% ground cover (measured in spring) prevented N. trichotoma seedling recruitment. Relatively small amounts of perennial grass (>0.5 t DM/ha measured in spring) resulted in mortality of N. trichotoma seedlings that had recruited earlier in the year, through the next summer. Flupropanate also markedly reduced native perennial grasses and substantially increased N. trichotoma seedling establishment 12 months after application. Rotational grazing to maintain adequate levels of DM was an important management tactic that prevented N. trichotoma establishment and survival.
Relationship of stem water potential and leaf conductance to vegetative growth of young olive trees in a hedgerow orchard
Authors: Gómez-del-Campo María , Leal A. , Pezuela C.
Published: March 2008

In 2005, four irrigation treatments were applied to a 3-year-old cv. Cornicabra orchard. In T1, wetted soil volume was maintained close to field capacity by irrigating when soil sensors indicated that soil water potential in the root zone had fallen to –0.03 MPa and 0.06 MPa from spring until 15 August and from 15 August until September, respectively. On those days, 8, 6, 4, and 2 h of irrigation was applied to T1, T2, T3, and T4, so that over the season they received 106, 81, 76 and 31 mm of irrigation, respectively. The high value for T3 was the result of a valve failure on 13 June. Measurements were maintained throughout the experimental period of relative extractable water (REW) to 1 m depth at the wetted volume (0.30 m from a drip emitter), shoot length, trunk diameter, stem water potential (Ψstem) and leaf conductance (gl). The irrigation treatment significantly affected REW (P < 0.10), Ψstem, gl and vegetative growth (P < 0.05). Ψstem, and trunk diameter were the least variable parameters and Ψstem and shoot growth were the most sensitive to water stress. Although T1 received 24% more water than T2, no significant differences were detected in vegetative growth. T2 should be considered the optimum irrigation value. The mean monthly Kc for T2 was 0.086. The failure of the valve in T3 simulated a wet spring followed by limited irrigation. Irrigation applied was similar to T2 but shoot growth stopped one month earlier and lower values of Ψstem and gl were observed after mid August. REW was highly related to vegetative growth, 66% of maximum being achieved at REW 0.53 and 50% at 0.45. gl was independant of plant or soil water status and did not determine vegetative growth. A strong relationship established Ψstem as a good indicator of vegetative growth and hence of water stress. Shoot growth was 66% of maximum at Ψstem –1.5 MPa and 50% at –1.8 MPa.
Male fertility restoration of wheat in Hordeum chilense cytoplasm is associated with 6HchS chromosome addition
Authors: Martín A. C. , Atienza S. G. , Ramírez M. C. , Barro F. , Martín A.
Published: March 2008

We report a new cytoplasmic male sterility (CMS) source in bread wheat (Triticum aestivum L.) designated as msH1. CMS has been identified during the process of obtaining alloplasmic bread wheat in different Hordeum chilense Roem. Schultz. cytoplasms. It was observed that when using the H. chilense H1 accession, the corresponding alloplasmic line was male sterile. This alloplasmic wheat is stable under different environmental conditions and it does not exhibit developmental or floral abnormalities, showing only slightly reduced height and some delay in heading. On examining microsporogenesis in the alloplasmic line, it was found that different stages of meiosis were completed normally, but abnormal development occurred at the uninucleate-pollen stage at the first mitosis, resulting in failure of anther exertion and pollen abortion. Fertility restoration of the CMS phenotype caused by the H. chilense cytoplasm was associated with the addition of chromosome 6HchS from H. chilense accession H1. Thus, some fertility restoration genes appear to be located in this chromosome arm. Considering the features displayed by the msH1 system, we consider that it has a great potential for the development of viable technology for hybrid wheat production.
Theoretical investigation into the dissolved oxygen levels in follicular fluid of the developing human follicle using mathematical modelling
Authors: Redding Gabe P. , Bronlund John E. , Hart Alan L.
Published: March 2008

Oxygen levels in the follicle are likely to be critical to follicle development. However, a quantitative description of oxygen levels in the follicle is lacking. Mathematical modelling was used to predict the dissolved oxygen levels in the follicular fluid of the developing human follicle. The model predictions showed that follicular fluid dissolved oxygen levels are highly variable among follicles, due to the unique geometry of individual follicles. More generally, predictions showed that oxygen levels in follicular fluid increase rapidly during the initial early antral stages of follicle growth before peaking in the later early antral phase. Follicular fluid dissolved oxygen levels then decline through to the beginning of the pre-ovulatory phase, from which they increase through to ovulation. Based on the best available parameter estimates, the model predictions suggest that the mean dissolved oxygen levels in human follicular fluid during the late antral and pre-ovulatory phases range between 11 and 51 mmHg (~1.5–6.7 vol%). These predictions suggest that the human ovarian follicle is a low-oxygen environment that is often challenged by hypoxia, and are in agreement with only some published data on follicular fluid oxygen levels. Predictions are discussed in relation to follicle health and oocyte culture.
Testosterone secretion, testicular histology and the cryopreservation of cauda epididymidal spermatozoa in the common ringtail possum (Pseudocheirus peregrinus)
Authors: Phillips D. J. , McKinnon A. , Keeley T. , Johnston S. D.
Published: March 2008

The present study reports novel aspects of the reproductive biology of the male common ringtail possum (Pseudocheirus peregrinus). Plasma testosterone was measured through a stimulation test using the gonadotrophin-releasing hormone agonist, buserelin. Following intra-muscular administration of buserelin, there was an increase (P < 0.05) in testosterone concentration in the peripheral circulation 4 h later. Quantitative testicular histology of this species was described for the first time. Eight stages of the seminiferous epithelium cycle were identified in 10 possums and their relative frequency determined. Spermatozoa were recovered from the cauda epididymides of hemi-castrated possums and cryopreservation conducted in straws (6°C min–1) using final glycerol concentrations ranging between 2 and 20% in Tris-citrate egg yolk extender (v/v). Frozen straws were thawed and post-thaw motility, rate of motility, the percentage of live–dead spermatozoa and the percentage of sperm with swollen decondensed nuclei recorded. Similar to other marsupial sperm, common ringtail possum cauda epididymidal spermatozoa required high levels of glycerol (10–16%) in order to maintain post-thaw viability.
Confinement of caspase-12 proteolytic activity to autoprocessing
Authors: Roy Sophie , Sharom Jeffrey R. , Houde Caroline , Loisel Thomas P. , Vaillancourt John P. , Shao Wei , Saleh Maya , Nicholson Donald W.
Published: March 2008

Caspase-12 is a dominant-negative regulator of caspase-1 (IL-1β-converting enzyme) and an attenuator of cytokine responsiveness to septic infections. This molecular role for caspase-12 appears to be akin to the role of cFLIP in regulating caspase-8 in the extrinsic cell death pathway; however, unlike cFLIP/Usurpin, we demonstrate here that caspase-12 is catalytically competent. To examine these catalytic properties, rat caspase-12 was cloned, and the recombinant enzyme was used to examine the cleavage of macromolecular and synthetic fluorogenic substrates. Although caspase-12 could mediate autoproteolytic maturation of its own proenzyme, in both
cis
and
trans
, it was not able to cleave any other polypeptide substrate, including other caspase proenzymes, apoptotic substrates, cytokine precursors, or proteins in the endoplasmic reticulum that normally undergo caspase-mediated proteolysis. The dearth of potential substrates for caspase-12 also was confirmed by whole-cell diagonal-gel analysis. Autolytic cleavage within the caspase-12 proenzyme was mapped to a single site at the large–small subunit junction, ATAD
319
, and this motif was recognized by caspase-12 when incorporated into synthetic fluorogenic substrates. The specific activity of caspase-12 with these substates was several orders of magnitude lower than caspases-1 and -3, highlighting its relative catalytic paucity. In intact cells, caspase-12 autoproteolysis occurred in the inhibitory complex containing caspase-1. We propose that the proteolytic activity of caspase-12 is confined to its own proenzyme and that autocleavage within the caspase-1 complex may be a means for temporal limitation of the inhibitory effects of caspase-12 on proinflammatory cytokine maturation.
Alzheimer's disease is associated with reduced expression of energy metabolism genes in posterior cingulate neurons
Authors: Liang Winnie S. , Reiman Eric M. , Valla Jon , Dunckley Travis , Beach Thomas G. , Grover Andrew , Niedzielko Tracey L. , Schneider Lonnie E. , Mastroeni Diego , Caselli Richard , Kukull Walter , Morris John C. , Hulette Christine M. , Schmechel Donald , Rogers Joseph , Stephan Dietrich A.
Published: March 2008

Alzheimer's disease (AD) is associated with regional reductions in fluorodeoxyglucose positron emission tomography (FDG PET) measurements of the cerebral metabolic rate for glucose, which may begin long before the onset of histopathological or clinical features, especially in carriers of a common AD susceptibility gene. Molecular evaluation of cells from metabolically affected brain regions could provide new information about the pathogenesis of AD and new targets at which to aim disease-slowing and prevention therapies. Data from a genome-wide transcriptomic study were used to compare the expression of 80 metabolically relevant nuclear genes from laser-capture microdissected non-tangle-bearing neurons from autopsy brains of AD cases and normal controls in posterior cingulate cortex, which is metabolically affected in the earliest stages; other brain regions metabolically affected in PET studies of AD or normal aging; and visual cortex, which is relatively spared. Compared with controls, AD cases had significantly lower expression of 70% of the nuclear genes encoding subunits of the mitochondrial electron transport chain in posterior cingulate cortex, 65% of those in the middle temporal gyrus, 61% of those in hippocampal CA1, 23% of those in entorhinal cortex, 16% of those in visual cortex, and 5% of those in the superior frontal gyrus. Western blots confirmed underexpression of those complex I–V subunits assessed at the protein level. Cerebral metabolic rate for glucose abnormalities in FDG PET studies of AD may be associated with reduced neuronal expression of nuclear genes encoding subunits of the mitochondrial electron transport chain.
Bidirectional membrane tube dynamics driven by nonprocessive motors
Authors: Shaklee Paige M. , Idema Timon , Koster Gerbrand , Storm Cornelis , Schmidt Thomas , Dogterom Marileen
Published: March 2008

In cells, membrane tubes are extracted by molecular motors. Although individual motors cannot provide enough force to pull a tube, clusters of such motors can. Here,weinvestigate, using a minimal
in vitro
model system, how the tube pulling process depends on fundamental properties of the motor species involved. Previously, it has been shown that processive motors can pull tubes by dynamic association at the tube tip. We demonstrate that, remarkably, nonprocessive motors can also cooperatively extract tubes. Moreover, the tubes pulled by nonprocessive motors exhibit rich dynamics as compared to those pulled by their processive counterparts. We report distinct phases of persistent growth, retraction, and an intermediate regime characterized by highly dynamic switching between the two. We interpret the different phases in the context of a single-species model. The model assumes only a simple motor clustering mechanism along the length of the entire tube and the presence of a length-dependent tube tension. The resulting dynamic distribution of motor clusters acts as both a velocity and distance regulator for the tube. We show the switching phase to be an attractor of the dynamics of this model, suggesting that the switching observed experimentally is a robust characteristic of nonprocessive motors. A similar system could regulate
in vivo
biological membrane networks.
Domestication of the donkey: Timing, processes, and indicators
Authors: Rossel Stine , Marshall Fiona , Peters Joris , Pilgram Tom , Adams Matthew D. , O'Connor David
Published: March 2008

Domestication of the donkey from the African wild ass transformed ancient transport systems in Africa and Asia and the organization of early cities and pastoral societies. Genetic research suggests an African origin for the donkey, but pinpointing the timing and location of domestication has been challenging because donkeys are uncommon in the archaeological record and markers for early phases of animal domestication are hard to determine. We present previously undescribed evidence for the earliest transport use of the donkey and new paleopathological indicators for early phases of donkey domestication. Findings are based on skeletal data from 10 ≈5,000-year-old ass skeletons recently discovered entombed in an early pharaonic mortuary complex at Abydos, Middle Egypt, and a concurrent study of 53 modern donkey and African wild ass skeletons. Morphometric studies showed that Abydos metacarpals were similar in overall proportions to those of wild ass, but individual measurements varied. Midshaft breadths resembled wild ass, but midshaft depths and distal breadths were intermediate between wild ass and domestic donkey. Despite this, all of the Abydos skeletons exhibited a range of osteopathologies consistent with load carrying. Morphological similarities to wild ass show that, despite their use as beasts of burden, donkeys were still undergoing considerable phenotypic change during the early Dynastic period in Egypt. This pattern is consistent with recent studies of other domestic animals that suggest that the process of domestication is slower and less linear than previously thought.
A trispeciesAspergillusmicroarray: Comparative transcriptomics of threeAspergillusspecies
Authors: Andersen Mikael R. , Vongsangnak Wanwipa , Panagiotou Gianni , Salazar Margarita P. , Lehmann Linda , Nielsen Jens
Published: March 2008

The full-genome sequencing of the filamentous fungiAspergillus nidulans,Aspergillus niger, andAspergillus oryzaehas opened possibilities for studying the cellular physiology of these fungi on a systemic level. As a tool to explore this, we are making available an Affymetrix GeneChip developed for transcriptome analysis of any of the three above-mentioned aspergilli. Transcriptome analysis of triplicate batch cultivations of all three aspergilli on glucose and xylose media was used to validate the performance of the microarray. Gene comparisons of all three species and cross-analysis with the expression data identified 23 genes to be a conserved response acrossAspergillussp., including the xylose transcriptional activator XlnR. A promoter analysis of the up-regulated genes in all three species indicates the conserved XlnR-binding site to be 5′-GGNTAAA-3′. The composition of the conserved gene-set suggests that xylose acts as a molecule, indicating the presence of complex carbohydrates such as hemicellulose, and triggers an array of degrading enzymes. With this case example, we present a validated tool for transcriptome analysis of threeAspergillusspecies and a methodology for conducting cross-species evolutionary studies within a genus using comparative transcriptomics.
Specific requirement of the chromatin modifier mSin3B in cell cycle exit and cellular differentiation
Authors: David Gregory , Grandinetti Kathryn B. , Finnerty Patricia M. , Simpson Natalie , Chu Gerald C. , DePinho Ronald A.
Published: March 2008

The Sin3-histone deacetylase (HDAC) corepressor complex is conserved from yeast to humans. Mammals possess two highly related Sin3 proteins, mSin3A and mSin3B, which serve as scaffolds tethering HDAC enzymatic activity, and numerous sequence-specific transcription factors to enable local chromatin regulation at specific gene targets. Despite broad overlapping expression of mSin3A and mSin3B, mSin3A is cell-essential and vital for early embryonic development. Here, genetic disruption of mSin3B reveals a very different phenotype characterized by the survival of cultured cells and lethality at late stages of embryonic development with defective differentiation of multiple lineages—phenotypes that are strikingly reminiscent of those associated with loss of retinoblastoma family members or E2F transcriptional repressors. Additionally, we observe that, whereas mSin3B
−/−
cells cycle normally under standard growth conditions, they show an impaired ability to exit the cell cycle with limiting growth factors. Correspondingly, mSin3B interacts physically with the promoters of known E2F target genes, and its deficiency is associated with derepression of these gene targets
in vivo
. Together, these results reveal a critical role for mSin3B in the control of cell cycle exit and terminal differentiation in mammals and establish contrasting roles for the mSin3 proteins in the growth and development of specific lineages.
Integration of light and abscisic acid signaling during seed germination and early seedling development
Authors: Chen Hao , Zhang Jingyu , Neff Michael M. , Hong Suk-Whan , Zhang Huiyong , Deng Xing-Wang , Xiong Liming
Published: March 2008

Seed germination is regulated by endogenous hormonal cues and external environmental stimuli such as water, low temperature, and light. After germination, the young seedling must rapidly establish its root system and the photoautotrophic capability appropriate to its surrounding environment. Light and the phytohormone abscisic acid (ABA) both regulate seed germination and seedling development, although how light and ABA signals are integrated at the molecular level is not understood. Here, we found that the previously described light-signaling component HY5 also mediates ABA response in seed germination, early seedling growth, and root development in
Arabidopsis
. HY5 binds to the promoter of the transcription factor
ABI5
gene with high affinity and is required for the expression of
ABI5
and ABI5-targeted late embryogenesis-abundant genes in seeds. Chromatin immunoprecipitation also indicated that the binding of HY5 to the
ABI5
promoter is significantly enhanced by ABA. Overexpression of ABI5 restores ABA sensitivity in
hy5
and results in enhanced light responses and shorter hypocotyls in the wild type. Our studies identified an unexpected mode of light and ABA signal integration that may help young seedlings better adapt to environmental stresses.
Acetylcholinesterase inhibitors and Gulf War illnesses
Authors: Golomb Beatrice Alexandra
Published: March 2008

Increasing evidence suggests excess illness in Persian Gulf War veterans (GWV) can be explained in part by exposure of GWV to organophosphate and carbamate acetylcholinesterase inhibitors (AChEis), including pyridostigmine bromide (PB), pesticides, and nerve agents. Evidence germane to the relation of AChEis to illness in GWV was assessed. Many epidemiological studies reported a link between AChEi exposure and chronic symptoms in GWV. The link is buttressed by a dose–response relation of PB pill number to chronic symptoms in GWV and by a relation between avidity of AChEi clearance and illness, based on genotypes, concentrations, and activity levels of enzymes that detoxify AChEis. Triangulating evidence derives from studies linking occupational exposure to AChEis to chronic health symptoms that mirror those of ill GWV. Illness is again linked to lower activity of AChEi detoxifying enzymes and genotypes conferring less-avid AChEi detoxification. AChEi exposure satisfies Hill's presumptive criteria for causality, suggesting this exposure may be causally linked to excess health problems in GWV.
Correctly folded Pfs48/45 protein of
Plasmodium falciparum
elicits malaria transmission-blocking immunity in mice
Authors: Outchkourov Nikolay S. , Roeffen Will , Kaan Anita , Jansen Josephine , Luty Adrian , Schuiffel Danielle , van Gemert Geert Jan , van de Vegte-Bolmer Marga , Sauerwein Robert W. , Stunnenberg Hendrik G.
Published: March 2008

Malaria kills >1 million people each year, in particular in sub-Saharan Africa. Although asexual forms are directly responsible for disease and death, sexual stages account for the transmission of
Plasmodium
parasites from human to the mosquito vector and therefore the spread of the parasite in the population. Development of a malaria vaccine is urgently needed to reduce morbidity and mortality. Vaccines against sexual stages of
Plasmodium falciparum
are meant to decrease the force of transmission and consequently reduce malaria burden. Pfs48/45 is specifically expressed in sexual stages and is a well established transmission-blocking (TB) vaccine candidate. However, production of correctly folded recombinant Pfs48/45 protein with display of its TB epitopes has been a major challenge. Here, we show the production of a properly folded Pfs48/45 C-terminal fragment by simultaneous coexpression with four periplasmic folding catalysts in
Escherichia coli
. This C-terminal fragment fused to maltose binding protein was produced at medium scale with >90% purity and a stability over at least a 9-month period. It induces uniform and high antibody titers in mice and elicits functional TB antibodies in standard membrane feeding assays in 90% of the immunized mice. Our data provide a clear perspective on the clinical development of a Pfs48/45-based TB malaria vaccine.
The Aboriginal Tea Ceremony: Its Relevance to Psychiatric Practice
Authors: Hunter Ernest
Published: March 2008

Objective: To examine the elements of the Aboriginal tea ceremony and its relevance to psychiatric practice.

Conclusions: Through the Aboriginal tea ceremony, the mental health professional is able to convey that care and concern balance experience and expertise. These underpinning principles have wide application.
A Cross-Sectional Survey of the Frequency and Characteristics of Delusions in Acute Psychiatric Wards
Authors: Brakoulias Vlasios , Starcevic Vladan
Published: March 2008

Objective: The aim of this paper was to ascertain the frequency and characteristics of delusions across several acute psychiatric wards.

Method: A survey of the files of all 160 acute psychiatric inpatients aged 18–65 years within Western Sydney was conducted. Patients recorded as currently delusional were compared to non-delusional psychotic patients on demographic data, diagnoses, reason for admission, mode of admission, length of hospital stay, legal status, and treatments.

Results: More than one-half of all patients in the acute psychiatric wards were recorded as being delusional. Persecutory delusions were found in 80% of delusional patients, and multiple delusions were common. Most delusions were steady in course, and 40% lasted longer than 6 months. Patients with delusions received a diagnosis of schizophrenia in 67% of the cases, while 72% of patients with schizophrenia were recorded as having delusions. Almost 90% of delusional patients were detained involuntarily. Antipsychotic medications were the mainstay of treatment for delusional patients, and 30% were treated with more than one antipsychotic. Non-pharmacological strategies for managing delusions were not used.

Conclusions: Delusions are commonly seen in acute psychiatric wards. There may be a relationship between the presence of delusions, severity of illness and treatment resistance. This highlights the need for a broad and more effective approach to management.
Psychiatry's Problem Child: PTSD in the Forensic Context: (Part 1)
Authors: Gaughwin Peter
Published: March 2008

Objective: The aim of this paper was to consider some of the recent literature that has raised questions about the prevalence of, and problems with, post-traumatic stress disorder (PTSD) in the forensic context and whether it is a failure by experts to consider adequately Criterion A (1), which leads them into error and results in a skewed picture of the prevalence of PTSD in litigation.

Method: The nature of the stressor criterion for PTSD from DSM-III to DSM-IV-TR, and recent literature relating to problems with the manner in which that stressor criterion is applied in forensic contexts, are considered.

Results: It becomes clear that, notwithstanding that the class of persons who can suffer PTSD after a particularly traumatic event has widened since it was included in the DSM-III, the nature of the stressor required before a diagnosis of PTSD can be made has remained fairly constant.

Conclusions: Whether it is because PTSD is commonly associated with receiving a benefit (e.g. through post-war disability benefits, victims of crime compensation or because of a desire to use it as an ideological weapon), PTSD has become a ubiquitous presence in the forensic context, notwithstanding objective (i.e. non-forensic) clinical studies which refer to its rarity. It is clear now that PTSD symptoms can be readily simulated when the simulator is seeking a benefit. It is also becoming clear that some psychiatrists are not being as rigorous in the forensic context as they might be in a clinical context. Thus, with discussion now underway regarding DSM-V, it may be timely to reconsider the utility of PTSD as a clinical condition.
Motivations for Self-Injury in an Adolescent Inpatient Population: Development of a Self-Report Measure
Authors: Swannell Sarah , Martin Graham , Scott James , Gibbons Marion , Gifford Shaune
Published: March 2008

Objective: The aim of this study was to develop and pilot an instrument for the assessment of self-injury in adolescent inpatients.

Methods: The Self-Injury Motivation Scale was modified for use in adolescents. Thirty-eight consenting adolescent inpatients with a history of self-injury completed the Self-Injury Motivation Scale – Adolescent version (SIMS-A) and the Self-Injury Interview (SII) to collect information about a range of factors associated with self-injury, other clinical variables and demographic details.

Results: The SIMS-A was acceptable to this adolescent sample and motivations for self-injury were similar to those of adults using the original SIMS scale. Adolescents were, however, more likely to use self-injury for communicating to/influencing others compared to adults. The participants most frequently reported self-injury by hitting, cutting and burning. The clinical diagnosis most frequently associated with self-injury was major depression. Females reported earlier onset, higher frequency and multiple methods of self-injury compared to males. Distraction from emotional pain was the most common motivation for self-injury in both males and females.

Conclusions: This pilot study suggests the SIMS-A is a useful self-report measure to assist clinicians and adolescent patients to understand a behaviour that may be associated with shame, guilt or other difficult emotions for the adolescent. Results also support the contention that there are often multiple and conflicting motivations for self-injury. Self-injury in this population was more common and severe in female adolescents compared to males, while clinical depression was a risk factor for self-injury in both males and females. The small sample size of adolescent inpatients is an important limitation of this pilot study, and research using the SIMS-A in larger samples is warranted.
Pre-Pubertal Paediatric Bipolar Disorder: A Controversy from America
Authors: Parry Peter , Allison Stephen
Published: March 2008

Objective: The aim of this paper was to explore the rapid rise in the diagnosis of bipolar disorder (BD) in the paediatric, particularly pre-pubertal, age group, in the USA over the past decade and to look at associated controversies.

Conclusions: There has been a very marked rise in the diagnosis of BD among pre-pubertal children, and to a lesser extent adolescents, in the USA since the mid 1990s. The rise appears to have been driven by a reconceptualizing of clusters of emotional and behavioural symptoms in the paediatric age group by some academic child psychiatry departments, most notably in St Louis, Boston and Cincinnati. There is controversy in both the academic literature and public media centring on diagnostic methods, epidemiological studies, adverse effects of medication including media-reported fatalities, and pharmaceutical company influence. With some exceptions, the traditional view of BD as being very rare prior to puberty and uncommon in adolescence appears accepted beyond the USA, though whether this is changing is as yet uncertain, and thus there are implications for Australian and New Zealand child and adolescent psychiatry.