bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of simultaneous source and bias pulsing in inductively coupled plasma etching
Authors: Agarwal Ankur , Stout Phillip J. , Banna Samer , Rauf Shahid , Tokashiki Ken , Lee Jeong-Yun , Collins Ken
Published: December 2009

Pulsed rf plasmas show promise to overcome challenges for plasma etching at future technological nodes. In pulsed plasmas, it is important to characterize the transient phenomena to optimize plasma processing of materials. In particular, it is important to evaluate the effect of the ion energy and angular distribution (IEAD) functions during pulsing on etching of nanoscale features. In this work, the impact of simultaneous pulsing of both source and bias in an inductively coupled plasma on plasma characteristics and feature profile evolution is discussed using results from a two-dimensional reactor scale plasma model coupled to a Monte Carlo based feature profile model. Results are discussed for an Ar∕Cl2 gas mixture which is typically used for poly-Si etching. The consequences of duty cycle, pulse shape, and the phase lag between source and bias power pulses on discharge characteristics, IEADs to the wafer, and feature profile evolution are discussed. The low plasma density during the initial period of the pulse was found to introduce a high energy tail component to the IEADs. This high energy tail component can be affected by modifying the pulse shape. The Si etching rate is found to increase with increasing duty cycle but is lower compared to continuous mode of operation due to lower time averaged power deposition. Pulsing the source and bias out of phase provides for increased ion energies and fluxes to the wafer for a given duty cycle.
Voltage-controlled negative resistance and electroluminescent spectra of Al–Al2O3–Au diodes
Authors: Hickmott T. W.
Published: December 2009

Dielectric breakdown of metal-insulator-metal (MIM) diodes can result in the development of voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics. Electroluminescence from the MIM diode appears at the same time as VCNR develops. The spectra of electroluminescence associated with VCNR of Al–Al2O3–Au diodes with anodic Al2O3 has been measured for photon energies between 1.8 eV, the lowest photon energy the photomultiplier can detect, and 3.4 eV, using narrow-band interference filters. Electroluminescent photons have maximum intensity between 1.8 and 2.4 eV with a peak at ∼2.2 eV. The voltage threshold for electroluminescence in Al–Al2O3–Au diodes, VTH, is 1.7 to 2.0 V; it is associated with an impurity band in amorphous Al2O3. Electrons injected into the impurity band can recombine with radiative centers in Al2O3 or can be emitted into vacuum. The range of values of VTH is the same as the range of values of the barrier height at the Al–Al2O3 interface measured by internal photo emission or by tunneling. The spectral data support a model of conduction and VCNR in a conducting channel. Dielectric breakdown and forming of VCNR introduce positive charge at the Al–Al2O3 interface that results in an Ohmic contact and a high field region in the conducting channel. Electrons injected into Al2O3 when the applied voltage is greater than VTH neutralize positive charge, change the Ohmic contact, and cause a decrease in current with increasing voltage. The radiative centers involved in electroluminescence are also responsible for other forms of luminescence in Al2O3.
Fabrication of 0-3 type manganite/insulator composites and manipulation of their magnetotransport properties
Authors: Yang H. , Cao Z. E. , Shen X. , Xian T. , Feng W. J. , Jiang J. L. , Feng Y. C. , Wei Z. Q. , Dai J. F.
Published: December 2009

In order to promote the technological applications of perovskite manganites, a great fundamental interest has been devoted to tailoring and/or enhancing their magnetotransport properties. Design and fabrication of manganite-based nanocomposites offer great potential to tailor the magnetotransport properties. In this work, we illustrate the promising concept of 0-3 type manganite/insulator composites (where manganite nanoparticles are uniformly and discretely embedded in a three-dimensional-connectivity insulator matrix) through the example of the La0.67Ca0.33MnO3 (LCMO)/MgO system. We present a promising strategy, which is based on the creation of core (LCMO)–shell (MgO) composite powders, for the synthesis of 0-3 type LCMO/MgO composites. A modified polyacrylamide gel method has been developed to prepare the core-shell structured LCMO/MgO composite powders. Besides its ability to create well-defined core-shell composite structures, the present gel method also allows the production of nanopowders with uniform particle size and in spherical shape. In our (1−x)LCMO/xMgO composite system, the lattice of LCMO is found to expand with rising MgO concentration x, yielding a bulk tensile strain. The increase in the tensile strain with x yields to a structural phase transition in the LCMO phase from an orthorhombic Pnma structure (x≤0.2) to a rhombohedral R3¯c structure (x≥0.3), and this structural transition leads to a relaxation of the strain. The strain effects induced by the MgO second phase exert a great influence on the ferromagnetic transition temperature TC. The composite system exhibits a percolative behavior in the conductivity, and the metal-insulator transition temperature TM-I decreases with x and is finally suppressed as the MgO content increases up to x=0.3. An enhancement in magnetoresistance (MR) is observed at low temperatures for the composites, and the low-field sensitivity of MR gets enhanced with the increase in MgO content. This work provides a promising method for manipulating the magnetotransport properties of manganites by composites with a proper insulator phase in a 0-3 connectivity fashion.
Geometric phases and squeezed quantum states of relic gravitons
Authors: Bakke Knut , Pedrosa I. A. , Furtado Claudio
Published: December 2009

In this work, we investigate the quantum effects of relic gravitons from a Schrödinger-picture point of view. By considering the gravity-wave equations in the Friedmann–Robertson–Walker cosmological background, we reduce the problem to that of a generalized time-dependent harmonic oscillator and find the corresponding exact analytic wave functions with the help of the dynamical invariant operator method. Afterward, we derive the geometric phases and squeezed quantum states for this system. We also evaluate the quantum fluctuations and the uncertainty product for each mode of the quantized field.
Effects of thermal annealing on the band alignment of lanthanum aluminate on silicon investigated by x-ray photoelectron spectroscopy
Authors: Liu Z. Q. , Chiam S. Y. , Chim W. K. , Pan J. S. , Ng C. M.
Published: December 2009

In this work, we investigate the changes in the band offsets of lanthanum aluminate on silicon after postdeposition annealing at 600 and 800 °C by x-ray photoelectron spectroscopy (XPS). It is found that annealing at 800 °C reduces the conduction band offset from 2.31 to 1.39±0.2 eV. A detailed analysis is performed to ascertain the origin of the changes. We will show that the observed band offset changes are not a consequence of alterations in the bulk properties of the oxide film, but rather a true band alignment change between the two materials. After systematically considering “artefacts” of XPS measurements, including extra-atomic relaxation and differential charging, we conclude that the band offset changes originate mainly from an interfacial effect. While intrinsic gap states dipoles are not sufficient to account for the large band offset shifts, we turned our attention to examine the interface of the gate oxide stack. We show the existence of at least two types of dipoles. One of the dipoles exists at the silicon-silicon oxide interface, while the strength of the other dipole can be correlated with the thickness and the chemical stoichiometry of the interfacial silicate.
Experimental vortex breakdown topology in a cylinder with a free surface
Authors: Lo Jacono David , Nazarinia Mehdi , Brøns Morten
Published: December 2009

The free surface flow in a circular cylinder driven by a rotating bottom disk is studied experimentally using particle image velocimetry. Results are compared with computational results assuming a stress-free surface. A dye visualization study by Spohn et al. [“Observations of vortex breakdown in an open cylindrical container with a rotating bottom,” Exp. Fluids 14, 70 (1993)], as well as several numerical computations, has found a range of different vortex breakdown structures in this flow. We confirm the existence of a transition where the top of the breakdown bubble crosses from the axis to the surface, which has previously only been found numerically. We employ a technique by Brøns et al. [“Topology of vortex breakdown bubbles in a cylinder with rotating bottom and free surface,” J. Fluid Mech. 428, 133 (2001)] to find the corresponding bifurcation curve in the parameter plane, which has hitherto only been used on numerical data. The bifurcation curve located here agrees well with previous numerical simulations. For low values of the Reynolds number we find a regime with vortex breakdown that has not been previously identified. Experiments deviate substantially from computations, indicating the importance of surface effects in this regime.
All-optical conditional logic with a nonlinear photonic crystal nanocavity
Authors: McCutcheon Murray W. , Rieger Georg W. , Young Jeff F. , Dalacu Dan , Poole Philip J. , Williams Robin L.
Published: December 2009

We demonstrate tunable frequency-converted light mediated by a χ(2) nonlinear photonic crystal nanocavity. The InP-based cavity supports two closely spaced localized modes near 1550 nm, which are resonantly excited by a 130 fs laser pulse. The cavity is simultaneously irradiated with a nonresonant probe beam, giving rise to rich second-order scattering spectra showing nonlinear mixing of the different resonant and nonresonant components. We highlight the radiation at the sum frequencies of the probe beam and the respective cavity modes. This would be a useful, minimally invasive monitor of the joint occupancy state of multiple cavities in an integrated optical circuit.
Fronts and nonlinear waves in a simplified shallow-water model of the atmosphere with moisture and convection
Authors: Bouchut François , Lambaerts Julien , Lapeyre Guillaume , Zeitlin Vladimir
Published: December 2009

We describe a shallow-water type atmospheric model which includes the transport of moisture as well as related precipitation and convection effects. The model combines hydrodynamic nonlinearity of the standard shallow-water model with the intrinsic nonlinearity due to the precipitation threshold. It allows for both theoretical treatment by the method of characteristics and efficient numerical resolution using shock-capturing finite-volume schemes. Linearized in the dynamical sector, the model adequately reproduces the propagation of the edge of precipitation regions (precipitation fronts) found in earlier studies. Results of numerical experiments on simple wave scattering upon a moisture front are in agreement with analytical results and highlight the role of dissipative reflector played by precipitating zones. We also analyze the evolution of a disturbance propagating in a uniformly saturated region and obtain criteria for precipitation front formation. Finally, we simulate wave breaking as an example of essentially nonlinear phenomenon and show how moist effects modify the classical shock formation scenario.
Coaxial nanocables of codoped double-walled carbon nanotubes
Authors: Yang Yurong , Yan X. H. , Lu Di , Cao J. X.
Published: December 2009

The electronic and optical properties of codoped double-walled carbon nanotubes (DWNTs), in which nucleophilic atoms (potassium) are adsorbed outside the outer tube and electrophilic molecules (NO2) are adsorbed inside the inner tube, are investigated by density functional theory. It is found that the inner core tube is p-type doped and the outer shell tube is n-type doped, forming a radial p-n junction of DWNTs. A type-II band energy alignment is formed at the interface of two constituting walls of codoped DWNTs. Moreover, optical calculations show that the band edge absorption is zero for pristine DWNTs, while it is pronounced for the codoped DWNTs. This absorption of codoped DWNTs leads to charge separation in the interface of two walls of DWNTs with holes located on core tube while electrons located on shell one. The properties of DWNT coaxial nanocables demonstrated here can find future applications in electronic and optoelectronic devices.
Further aspects on the control of photodissociation in light-induced potentials
Authors: Chang Bo Y. , Shin Seokmin , Sola Ignacio R.
Published: December 2009

In this work we show how to control the photodissociation of a diatomic molecule in the frame of light-induced potentials for different shapes of the transition dipole moments. A sequence of a half-cycle or control pulse and a delayed pump pulse is used for achieving state-selective photodissociation with high yields. The effect of the control is to shift the photodissociation bands to higher frequencies. It is also possible to dissociate the molecule in a superposition of electronic states of the fragments, even when the photodissociation bands corresponding to the different electronic states of the products are largely separated. In this case one needs to engineer the sequence delaying the half-cycle pulse after the pump pulse and additionally turning off rapidly the control pulse. Depending on the shape of the dipole functions the duration of the pulses in the sequence must be constrained to shorter times as well. Finally we show that the control scheme affects the velocity of the fragments. Although broad kinetic energy distributions are always obtained when the half-cycle pulse is short, if the Stark effect implies a blueshifting in the energy of the electronic states, the distribution of the relative speed of the fragments will be redshifted.
Calculation of the dielectric constant ϵ and first nonlinear susceptibility χ(2) of crystalline potassium dihydrogen phosphate by the coupled perturbed Hartree–Fock and coupled perturbed Kohn–Sham schemes as implemented in the CRYSTAL code
Authors: Lacivita Valentina , Rérat Michel , Kirtman Bernard , Ferrero Mauro , Orlando Roberto , Dovesi Roberto
Published: December 2009

The high-frequency dielectric ϵ and the first nonlinear electric susceptibility χ(2) tensors of crystalline potassium dihydrogen phosphate (KH2PO4) are calculated by using the coupled perturbed Hartree–Fock and Kohn–Sham methods as implemented in the CRYSTAL code. The effect of basis sets of increasing size on ϵ and χ(2) is explored. Five different levels of theory, namely, local-density approximation, generalized gradient approximation (PBE), hybrids (B3LYP and PBE0), and HF are compared using the experimental and theoretical structures corresponding not only to the tetragonal geometry I4¯d2 at room temperature but also to the orthorhombic phase Fdd2 at low temperature. Comparison between the two phases and their optical behavior is made. The calculated results for the tetragonal phase are in good agreement with the experimental data.
Structural and electronic properties of oxidized sodium clusters: A combined photoelectron and density functional study
Authors: Majer Kiran , Lei Ma , Hock Christian , von Issendorff Bernd , Aguado Andrés
Published: December 2009

Oxygen-doped sodium cluster anions NanO2− with n=41–148 have been studied by low temperature photoelectron spectroscopy and density functional theory (DFT), with a particular emphasis on those sizes where a spherical electron shell closing is expected. The experimental spectra are in good agreement with the electronic density of states of the DFT lowest energy structures. The cluster structures show segregation between an ionically bonded molecular unit located at the cluster surface and a metallic part. The DFT calculations reveal that each oxygen atom removes two electrons from the metallic electron gas in order to become an O2− dianion. A jellium model would therefore predict the electron shell closings to be shifted up by four sodium atoms with respect to pure Nan− cluster anions. The electron shell closings for NanO2− are located at n=43, 61, 93, and 139, so the expected four-atom shift is observed only for the small clusters of up to n=61, while a two-atom shift is observed for the larger clusters. The DFT calculations explain this departure from jellium model predictions in terms of a structural transition in the ionically bonded molecular unit.
Nonlinear breathing processes in granular alignments
Authors: Simion Robert P. , Sokolow Adam , Sen Surajit
Published: December 2009

A compressive applied force at the zero frequency limit applied on confined granular alignments is shown to result in tunable and higher frequency nonlinear granular breathing. We use extensive dynamical simulations and simple arguments to probe the origins of these breathing processes. In the presence of dissipation, the breathing has a lifetime that is inversely proportional to the dissipation constant. The possible use of the concept of nonlinear granular breathing in recovering the energy released at the beaches by surface gravity waves using a system made largely of nonmoving parts is mentioned as a possible application.
Visualization of accumulated charge density in operating organic thin-film transistors
Authors: Matsui Hiroyuki , Hasegawa Tatsuo
Published: December 2009

We developed the technique of charge-induced elastic modulation interferometry for analyzing the local densities of accumulated charge in organic thin-film transistors. The technique uses the Fabry–Perot interference at an elastic polymeric gate dielectric layer, the thickness of which is slightly modulated by electrostatic forces between the accumulated charges. The method permits visualization of the temporal evolution of charging and discharging of the channel layer when a pulsed switched gate voltage is applied. We also performed a spatially resolved analysis of the frequency response along a channel; these results can be explained in terms of a distributed constant circuit model.
Characteristics of indium-tin-oxide Schottky contacts to ZnMgO/ZnO heterojunctions with band gap grading
Authors: Yoon Jong-Gul , Cho Sung Woo , Lee E. , Chung J.-S.
Published: December 2009

We report on electrical characteristics of indium-tin-oxide (ITO) Schottky contacts to transparent n-n isotype heterojunctions composed of a compositionally graded Zn1−xMgxO (g-ZnMgO) and ZnO films fabricated on ITO-coated glass substrates. The transparent ITO Schottky contacts to g-ZnMgO/ZnO heterostructures resulted in excellent diode characteristics with the rectification ratios as high as 104 at a bias voltage of ±3.0 V. The effective Schottky barrier heights were about 0.6 eV and could be tuned by modifying the electrical properties of g-ZnMgO layer. The formation of high barrier Schottky contacts was discussed in conjunction with a band gap grading and a highly resistive surface layer of g-ZnMgO.
Impact of effective shear strain on the equilibrium phases and polarization states of PbTiO3 thin film
Authors: Yan W. S. , Zhang R. , Xie Z. L. , Xiu X. Q. , Zheng Y. D. , Liu Z. G. , Xu S.
Published: December 2009

Many ways can be used to tune in-plane strains and thus to tailor the physical properties of ferroelectric films. Impact of effective shear strain on the equilibrium phases and polarization states of single-domain PbTiO3 thin film is investigated by a thermodynamic theory. The modeling results indicate that not only shear strain but also the orientations of polarization components produce profound impacts on the equilibrium phases of thin film, which is essentially different from the cases of S6=0. Different components of polarization can be controlled by temperature, in-plane strains, and especially shear strain.
Scalable, high-speed one-way quantum computer in coupled-cavity arrays
Authors: Lin G. W. , Zou X. B. , Lin X. M. , Guo G. C.
Published: December 2009

We propose an efficient method to realize a scalable, high-speed quantum computer in a two-dimensional (2D) array of coupled cavities, based on coherent displacements of an arbitrary state of cavity fields in a closed phase space. Because the nontrivial geometric phase shifts fast accumulate between the qubits in nearest-neighbor cavities, a large-scale 2D cluster state can be created within a short time. We discuss the feasibility of our method for scalable solid-state quantum computation.
Valence band offset and interface stoichiometry at epitaxial Si3N4/Si(111) heterojunctions formed by plasma nitridation
Authors: Lee Hong-Mao , Kuo Cheng-Tai , Shiu Hung-Wei , Chen Chia-Hao , Gwo Shangjr
Published: December 2009

Ultrathin β-Si3N4(0001) epitaxial films formed by N2-plasma nitridation of Si(111) substrates have been studied by photoelectron spectroscopy using synchrotron radiation. The valence band offset at the β-Si3N4/Si interface was determined by valence-band photoelectron spectra to be 1.8 eV. Furthermore, the Si 2p core-level emissions were analyzed for nitride (Si4+) and subnitride (Si3+ and Si+) components to characterize the interface stoichiometry. In contrast to the interfaces formed by ammonia thermal nitridation and N2-plasma nitridation at room temperature, the interface formed by N2-plasma nitridation at high substrate temperature is very close to subnitride free with an abrupt composition transition.
The effect of evaporation on fingering instabilities
Authors: Klentzman Jill , Ajaev Vladimir S.
Published: December 2009

We investigate the flow of evaporating thin films of viscous liquid on inclined solid substrates under the influence of gravity. A lubrication-type approach is used to develop a three-dimensional model of the flow including physical effects such as capillarity, gravity, Marangoni stresses, disjoining pressure, and evaporation. Numerical simulations are then carried out based on the model. The effect of evaporation on the so-called fingering instability that develops along the contact line in the transverse direction of the flow is studied. It is found that evaporation acts to suppress the instability if the evaporation number, a nondimensional measure of the mass flow rate across the interface, is above a critical value. The critical value decreases as the inclination angle is decreased. For the values of evaporation number below the critical one, the fingers grow initially but then saturate at a length that depends on the evaporation conditions. It is also shown that thermocapillarity acts to enhance the instability.
New technique probes structural elements of folded chromosomes
Authors: Miller Johanna
Published: December 2009

Chromosomes in a cell nucleus aren’t randomly arranged. Studying their twists and turns reveals organization on several length scales.
Stiff-string theory: Richard Feynman on piano tuning
Authors: Bryner John C.
Published: December 2009

In a letter to his piano tuner, the great theoretical physicist talks about how the nonzero stiffness of piano strings affects tuning, and he conjectures that piano tuners may need to pay more attention to ear-created harmonics.
Preconditioning-induced protection of photoreceptors requires activation of the signal-transducing receptor gp130 in photoreceptors
Authors: Ueki Yumi , Le Yun-Zheng , Chollangi Srinivas , Muller Werner , Ash John D.
Published: December 2009

Retinal degenerations are a class of neurodegenerative disorders that ultimately lead to blindness due to the death of retinal photoreceptors. In most cases, death is the result of long-term exposure to environmental, inflammatory, and genetic insults. In age-related macular degeneration, significant vision loss may take up to 70–80 years to develop. The protracted time to develop blindness suggests that retinal neurons have an endogenous mechanism for protection from chronic injury. Previous studies have shown that endogenous protective mechanisms can be induced by preconditioning animals with sublethal bright cyclic light. Such preconditioning can protect photoreceptors from a subsequent damaging insult and is thought to be accomplished through induced expression of protective factors. Some of the factors shown to be associated with protection bind and activate the signal transducing receptor gp130. To determine whether stress-induced endogenous protection of photoreceptors requires gp130, we generated conditional
gp130
knockout (KO) mice with the Cre/
lox
system and used light-preconditioning to induce neuroprotection in these mice. Functional and morphological analyses demonstrated that the retina-specific
gp130
KO impaired preconditioning-induced endogenous protection. Photoreceptor-specific
gp130
KO mice had reduced protection, although the Müller cell KO mice did not, thus gp130-induced protection was restricted to photoreceptors. Using an animal model of retinitis pigmentosa, we found that the photoreceptor-specific
gp130
KO increased sensitivity to genetically induced photoreceptor cell death, demonstrating that gp130 activation in photoreceptors had a general protective role independent of whether stress was caused by light or genetic mutations.
A DinB variant reveals diverse physiological consequences of incomplete TLS extension by a Y-family DNA polymerase
Authors: Jarosz Daniel F. , Cohen Susan E. , Delaney James C. , Essigmann John M. , Walker Graham C.
Published: December 2009

The only Y-family DNA polymerase conserved among all domains of life, DinB and its mammalian ortholog pol κ, catalyzes proficient bypass of damaged DNA in translesion synthesis (TLS). Y-family DNA polymerases, including DinB, have been implicated in diverse biological phenomena ranging from adaptive mutagenesis in bacteria to several human cancers. Complete TLS requires dNTP insertion opposite a replication blocking lesion and subsequent extension with several dNTP additions. Here we report remarkably proficient TLS extension by DinB fromEscherichia coli. We also describe a TLS DNA polymerase variant generated by mutation of an evolutionarily conserved tyrosine (Y79). This mutant DinB protein is capable of catalyzing dNTP insertion opposite a replication-blocking lesion, but cannot complete TLS, stalling three nucleotides after anN2-dG adduct. Strikingly, expression of this variant transforms a bacteriostatic DNA damaging agent into a bactericidal drug, resulting in profound toxicity even in adinB+background. We find that this phenomenon is not exclusively due to a futile cycle of abortive TLS followed by exonucleolytic reversal. Rather, gene products with roles in cell death and metal homeostasis modulate the toxicity of DinB(Y79L) expression. Together, these results indicate that DinB is specialized to perform remarkably proficient insertion and extension on damaged DNA, and also expose unexpected connections between TLS and cell fate.
Bacterial gut symbionts are tightly linked with the evolution of herbivory in ants
Authors: Russell Jacob A. , Moreau Corrie S. , Goldman-Huertas Benjamin , Fujiwara Mikiko , Lohman David J. , Pierce Naomi E.
Published: December 2009

Ants are a dominant feature of terrestrial ecosystems, yet we know little about the forces that drive their evolution. Recent findings illustrate that their diets range from herbivorous to predaceous, with “herbivores” feeding primarily on exudates from plants and sap-feeding insects. Persistence on these nitrogen-poor food sources raises the question of how ants obtain sufficient nutrition. To investigate the potential role of symbiotic microbes, we have surveyed 283 species from 18 of the 21 ant subfamilies using molecular techniques. Our findings uncovered a wealth of bacteria from across the ants. Notable among the surveyed hosts were herbivorous “turtle ants” from the related genera
Cephalotes
and
Procryptocerus
(tribe Cephalotini). These commonly harbored bacteria from ant-specific clades within the
Burkholderiales
,
Pseudomonadales
,
Rhizobiales
,
Verrucomicrobiales
, and
Xanthomonadales
, and studies of lab-reared
Cephalotes varians
characterized these microbes as symbiotic residents of ant guts. Although most of these symbionts were confined to turtle ants, bacteria from an ant-specific clade of
Rhizobiales
were more broadly distributed. Statistical analyses revealed a strong relationship between herbivory and the prevalence of
Rhizobiales
gut symbionts within ant genera. Furthermore, a consideration of the ant phylogeny identified at least five independent origins of symbioses between herbivorous ants and related
Rhizobiales
. Combined with previous findings and the potential for symbiotic nitrogen fixation, our results strongly support the hypothesis that bacteria have facilitated convergent evolution of herbivory across the ants, further implicating symbiosis as a major force in ant evolution.
Dynamin 2 orchestrates the global actomyosin cytoskeleton for epithelial maintenance and apical constriction
Authors: Chua Jennifer , Rikhy Richa , Lippincott-Schwartz Jennifer
Published: December 2009

The mechanisms controlling cell shape changes within epithelial monolayers for tissue formation and reorganization remain unclear. Here, we investigate the role of dynamin, a large GTPase, in epithelial morphogenesis. Depletion of dynamin 2 (Dyn2), the only dynamin in epithelial cells, prevents establishment and maintenance of epithelial polarity, with no junctional formation and abnormal actin organization. Expression of Dyn2 mutants shifted to a non-GTP state, by contrast, causes dramatic apical constriction without disrupting polarity. This is due to Dyn2's interactions with deacetylated cortactin and downstream effectors, which cause enhanced actomyosin contraction. Neither inhibitors of endocytosis nor GTP-shifted Dyn2 mutants induce apical constriction. This suggests that GTPase-dependent changes in Dyn2 lead to interactions with different effectors that may differentially modulate endocytosis and/or actomyosin dynamics in polarized cells. We propose this enables Dyn2 to coordinate, in a GTPase-dependent manner, membrane recycling and actomyosin contractility during epithelial morphogenesis.
Disrupting the prefrontal cortex diminishes the human ability to build a good reputation
Authors: Knoch Daria , Schneider Frédéric , Schunk Daniel , Hohmann Martin , Fehr Ernst
Published: December 2009

Reputation formation pervades human social life. In fact, many people go to great lengths to acquire a good reputation, even though building a good reputation is costly in many cases. Little is known about the neural underpinnings of this important social mechanism, however. In the present study, we show that disruption of the right, but not the left, lateral prefrontal cortex (PFC) with low-frequency repetitive transcranial magnetic stimulation (rTMS) diminishes subjects' ability to build a favorable reputation. This effect occurs even though subjects' ability to behave altruistically in the absence of reputation incentives remains intact, and even though they are still able to recognize both the fairness standards necessary for acquiring and the future benefits of a good reputation. Thus, subjects with a disrupted right lateral PFC no longer seem to be able to resist the temptation to defect, even though they know that this has detrimental effects on their future reputation. This suggests an important dissociation between the knowledge about one's own best interests and the ability to act accordingly in social contexts. These results link findings on the neural underpinnings of self-control and temptation with the study of human social behavior, and they may help explain why reputation formation remains less prominent in most other species with less developed prefrontal cortices.
The Communication Attitude Test (CAT‐S): normative values for 220 Swedish children
Authors: Johannisson Tove B. , Wennerfeldt Susanna , Havstam Christina , Naeslund Maria , Jacobson Kajsa , Lohmander Anette
Published: December 2009

Background: The risk of developing a negative attitude to communication as a consequence of having a speech disorder has been in focus for decades in research concerning fluency disorders in relation to both children and adults. The Communication Attitude Test (CAT), which was created to measure children's attitudes towards their own communication, has been widely used. Research has shown that children who stutter have a significantly more negative attitude to their own communication than normal‐speaking children and preliminary results show a similar picture in children with other types of speech disorders. However, the setting for obtaining data on normal‐speaking children often differs from that on children with speech disorders. In order to make a significant interpretation of results from children with a speech disorder, comparable data on normal‐speaking children are needed.

Aims: The main purpose of this study was to obtain norm values for the Swedish version of the test (CAT‐S) and examine possible differences related to age, sex or small town/big city. A second aim was to investigate some aspects of reliability, such as internal consistency, and validity in terms of item analysis as well as a qualitative analysis of the answers to the different items. In addition, group setting was compared with individual setting for the test procedure.

Methods & Procedures: CAT‐S was completed in a group setting by 220 normal‐speaking children aged 7–15 years and by an additional group of 35 normal‐speaking 10‐year‐old children who completed the test individually.

Outcomes & Results: The 220 Swedish children had a mean score of 6.05 (a slightly higher mean score have been found in other countries, i.e. Belgium = 7.05 and USA = 8.24). The 7‐year‐olds had a significantly higher mean score than children at the other ages, except for the 15‐year‐olds. No other differences were found related to age, sex or size of community. The aspects of reliability and validity investigated for the CAT‐S were satisfactory. Furthermore, there was no significant difference between the groups of 10‐year‐olds objected to different test procedures.

Conclusions & Implications: The norm values of CAT‐S could be used for comparison of scores from Swedish children with speech disorders. The CAT‐S is easy to administer and could be used either in a group setting for research purpose or individually at the clinic.
Gender Differences in Diagnoses of Mentally Disordered Offenders
Authors: Yourstone Jenny , Lindholm Torun , Grann Martin , Fazel Seena
Published: December 2009

We investigated differences in psychiatric diagnoses and medicolegal insanity decisions between female and male forensic psychiatric patients. Data on all offenders ( N = 4396) subjected to a court-ordered forensic psychiatric inpatient evaluation were obtained for the years 1992–2000. A significantly higher proportion of female mentally disordered offenders were given a diagnosis of personality disorder while mentally disordered male offenders more often had a diagnosis of alcohol and/or drug dependence or sexual disorders. There was an increased likelihood that violent women would be declared legally insane even after controlling for a number of potential confounders. This may reflect an underlying difference in the severity of psychiatric morbidity not accounted for diagnostically or that a gender bias exists in the forensic psychiatric evaluation process.
Not Guilty by Reason of Insanity (NGBRI)—Theory and Practice in Israel
Authors: Wallach Helene
Published: December 2009

The present study was undertaken to examine the differences in length of mandatory confinement under NGBRI and incarceration in Israel. Data was extracted from 100 files of male patients confined by court order and released prior to the study. For each crime purportedly committed by these patients, court files of men who were incarcerated due to the relevant crime were randomly pulled from court archives and similar data was extracted from these files. Incarcerated men were younger and less educated. In addition, more minority members are incarcerated than hospitalized. Correlation between length of hospitalization and maximum jail term allowed by law was not significant. Only five crimes had enough NGBRI cases in them to allow statistical comparisons. Of these, two were significant, and in both the length of incarceration was larger. Comparing hospitalization to incarceration for the remaining crimes produces a mixed picture. The committee was stricter than the attending psychiatrist when deciding on vacations, and release. These findings indicate that the length of hospitalization does not seem to be influenced by crime severity, nor by recovery from mental illness. Unfortunately, due to small numbers of hospitalized patients who committed each crime, statistical comparisons were difficult. Further research is necessary with larger numbers of patients. If in fact our finding that mental health is not sufficient to earn release from mandatory confinement is replicated, it will become important to determine a defined, short period of time for mandatory confinement, after which the individual is released or, if still sick, and/or posing a danger to him/herself or others, is transferred to the civil confinement route.
Treatment of Paraphilic Sexual Offenders in Brazil: Issues and Controversies
Authors: Baltieri DaniloAntonio , de Andrade ArthurGuerra
Published: December 2009

Psychopharmacological treatments have not only proven to be valuable but sometimes indispensable in the management of paraphilic sexual offenders. Despite not being approved by the FDA, some medications commonly used in paraphilic outpatients, such as Medroxyprogesterone and Leuprolide Acetate, cannot be considered an experimental or investigative medical procedure. Unfortunately, in Brazil, the use of hormonal medications for the treatment of dangerous sexual offenders has been seen as amoral and insufficiently effective and safe. This position creates many difficulties in the adequate management of sexual offenders in our country.
Perceived social support from team‐mates: Direct and stress‐buffering effects on self‐confidence
Authors: Freeman Paul , Rees Tim
Published: December 2009

In this study, we wished to determine whether the perceived support available from team‐mates predicts levels of self‐confidence. Four dimensions of support were examined: emotional, esteem, informational, and tangible. The sample consisted of 152 university athletes (74 females, 78 males) with a mean age of 20.1 years (s=1.4). Participants completed measures of perceived support, stressors, and self‐confidence at the training session before an important match. Moderated hierarchical regression analyses revealed that all four dimensions of support had direct effects on self‐confidence (ΔR 2=0.13–0.17, all P<0.01), with support positively predicting self‐confidence. Perceived emotional (ΔR 2=0.05, P<0.05), esteem (ΔR 2=0.02, P<0.05), and informational (ΔR 2=0.03, P <0.05) support also had stress‐buffering effects on self‐confidence. The findings suggest that although university athletes perceived different levels of emotional, esteem, informational, and tangible support to be available from their team‐mates, all four dimensions of support positively predicted self‐confidence.
Physiological and psychological responses to lead and top rope climbing for intermediate rock climbers
Authors: Draper Nick , Jones Glenys A. , Fryer Simon , Hodgson Christopher I. , Blackwell Gavin
Published: December 2009

Rock climbing is a popular adventure sport with an increasing research base. Early studies in the field did not make comparisons of ascents using different styles of climbing. More recently, differences in the physiological responses for an on‐sight lead climb and subsequent lead climb have been reported. The purpose of the present study was to examine the effect of style of climb (lead climb or top rope climb) on the physiological and psychological responses to rock climbing. Nine intermediate climbers volunteered for, and completed, two randomly assigned climbing trials and a maximum oxygen uptake (VO2max) test on a separate occasion. The climbers ascended the same 6a (sport grade) climb for both trials. Before climbing, heart rate, perception of anxiety (Revised Competitive State Anxiety Inventory‐2), and blood lactate concentration were measured. Climb time, heart rate, VO2, lactate concentrations, and task load (National Aeronautics and Space Administration Task Load Index) in response to each trial were also recorded. Results indicated significant differences (P<0.05) between the trials for climb time, blood lactate concentration immediately after and 15 min after climbing, and heart rate 1 min after climbing. During lead and top rope climbing, mean VO2 and represented 44% and 42% of treadmill VO2max and mean heart rate represented 81% and 77% of maximum heart rate, respectively. There were no significant differences in feelings of anxiety before either climb, although climbers reported the lead climb to be physically and mentally more demanding, requiring more effort and resulting in greater frustration (P<0.05) than the top rope climb. Our results indicate that the physiological and psychological responses of intermediate climbers are different for a lead climb and top rope climb.
Risk Factors for Endometritis after Low Transverse Cesarean Delivery
Authors: Olsen Margaret A. , Butler Anne M. , Willers Denise M. , Gross Gilad A. , Devkota Preetishma , Fraser Victoria J.
Published: December 2009

Objective.

To determine independent risk factors for endometritis after low transverse cesarean delivery.

Study Design.

We performed a retrospective case-control study during the period from July 1999 through June 2001 in a large tertiary care academic hospital. Endometritis was defined as fever beginning more than 24 hours or continuing for at least 24 hours after delivery plus fundal tenderness in the absence of other causes for fever. Independent risk factors for endometritis were determined by means of multivariable logistic regression. A fractional polynomial method was used to examine risk of endometritis associated with the continuous variable, duration of rupture of membranes.

Results.

Endometritis was identified in 124 (7.7%) of 1,605 women within 30 days after low transverse cesarean delivery. Independent risk factors for endometritis included younger age (odds ratio [OR], 0.93 [95% confidence interval {CI}, 0.90-0.97]) and anemia or perioperative blood transfusion (OR, 2.18 [CI, 1.30-3.68] ). Risk of endometritis was marginally associated with a proxy for low socioeconomic status, lack of private health insurance (OR, 1.72 [CI, 0.99-3.00]); with amniotomy (OR, 1.69 [CI, 0.97-2.95]); and with longer duration of rupture of membranes.

Conclusion.

Risk of endometritis was independently associated with younger age and anemia and was marginally associated with lack of private health insurance and amniotomy. The odds of endometritis increased approximately 1.7-fold within 1 hour after rupture of membranes, but increased duration of rupture was only marginally associated with increased risk. Knowledge of these risk factors can guide selective use of prophylactic antibiotics during labor and heighten awareness of the risk in subgroups at highest risk of infection.
Attributable Costs of Enterococcal Bloodstream Infections in a Nonsurgical Hospital Cohort
Authors: Butler Anne M. , Olsen Margaret A. , Merz Liana R. , Guth Rebecca M. , Woeltje Keith F. , Camins Bernard C. , Fraser Victoria J.
Published: December 2009

Background.

Vancomycin-resistantEnterococcus(VRE) bloodstream infections (BSIs) are associated with increased morbidity and mortality.

Objective.

To determine the hospital costs and length of stay attributable to VRE BSI and vancomycin-sensitiveEnterococcus(VSE) BSI and the independent effect of vancomycin resistance on hospital costs.

Methods.

A retrospective cohort study was conducted of 21,154 nonsurgical patients admitted to an academic medical center during the period from 2002 through 2003. Using administrative data, attributable hospital costs (adjusted for inflation to 2007 US dollars) and length of stay were estimated with multivariate generalized least-squares (GLS) models and propensity score-matched pairs.

Results.

The cohort included 94 patients with VRE BSI and 182 patients with VSE BSI. After adjustment for demographics, comorbidities, procedures, nonenterococcal BSI, and early mortality, the costs attributable to VRE BSI were $4,479 (95% confidence interval [CI], $3,500-$5,732) in the standard GLS model and $4,036 (95% CI, $3,170-$5,140) in the propensity score-weighted GLS model, and the costs attributable to VSE BSI were $2,250 (95% CI, $l,758-$2,880) in the standard GLS model and $2,023 (95% CI, $1,588-$2,575) in the propensity score-weighted GLS model. The median values of the difference in costs between matched pairs were $9,949 (95% CI, $1,579-$24,693) for VRE BSI and $5,282 (95% CI, $2,042-$8,043) for VSE BSI. The costs attributable to vancomycin resistance were $1,713 (95% CI, $1,338-$2,192) in the standard GLS model and $1,546 (95% CI, $1,214-$1,968) in the propensity score-weighted GLS model. Depending on the statistical method used, attributable length of stay estimates ranged from 2.2 to 3.5 days for patients with VRE BSI and from 1.1 to 2.2 days for patients with VSE BSI.

Conclusions.

VRE BSI and VSE BSI were independently associated with increased hospital costs and increased length of stay. Vancomycin resistance was associated with increased costs.
Patterns of Influenza Vaccination among Medical Students
Authors: Milunic Stacey L. , Quilty James F. , Super Dennis M. , Noritz Garey H.
Published: December 2009

This report examines patterns of influenza vaccination among preclinical and clinical medical students. We used an anonymous online survey to examine medical student behavior and knowledge. Students on clinical rotations, women, and students with better knowledge about the vaccine were more likely to receive the vaccine.
Variations in Hospital Daily Cleaning Practices
Authors: Boyce John M. , Havill Nancy L. , Lipka Abigail , Havill Heather , Rizvani Ramo
Published: December 2009

Prospective observations and adenosine triphosphate bioluminescence assays were used to evaluate daily cleaning practices in a university-affiliated hospital. Substantial variations were found in the amount of time spent cleaning high-touch surfaces, in the number of disinfectant wipes used in each room, and in the level of cleanliness achieved by housekeepers.
Four Years of Surveillance Cultures at a Long-Term Acute Care Hospital
Authors: Munoz-Price L. Silvia , Sterner Alexander
Published: December 2009

Objective.

To characterize the degree of colonization with multidrug-resistant organisms (MDROs) among patients admitted to a long-term acute care hospital.

Design.

Ecologie Study.

Setting.

A 70-bed long-term acute care hospital (a hospital within a hospital) in the greater Chicago area.

Methods.

As part of an infection control initiative, specimens were collected from all consecutively admitted patients for culture of MDROs within 72 hours of admission. Cultures from July 28, 2005, through November 1, 2008, were analyzed on the basis of the bodily site from which the isolate was recovered and the organisms identified. If MDROs were yielded by culture of specimens that were obtained from 24 hours to 30 days after collection of the patient's original set of specimens, these MDROs were removed from the analysis. In addition, repeat rectal swab samples were collected for culture at 2 weeks after admission for all consecutive patients admitted from January 1 through March 31, 2007.

Results.

A total of 1,739 patients with a total of 5,198 specimens met entry criteria. Of the corresponding 5,198 surveillance cultures, 1,580 (30%) were positive for MDROs. Of the 1,739 patients, 947 (54%) had a culture-positive specimen recovered from any site. Vancomycin-resistant Enterococcus was the organism most commonly isolated in cultures of rectal swab samples (in 38% of such cultures) and wounds (in 18% of such cultures). The rate of rectal carriage of vancomycin-resistant Enterococcus increased from 29% in 2005 to 44% in 2008.