bluuebunny/crossref_metadata_2025 huggingface dataset:
Can a ‘return-to-work’ agenda fit within the theory and practice of CBT for depression and anxiety disorders?
Authors: Wesson Matthew , Gould Matthew
Published: April 2010

Helping service users to return to work has emerged as a key therapeutic objective of the Improving Access to Psychological Therapies (IAPT) initiative. IAPT programmes implement National Institute for Health and Clinical Excellence (NICE) guidelines, especially cognitive behaviour therapy (CBT), for people suffering from anxiety and depression. However, relatively little research has been conducted to date into whether, or how, cognitive behavioural interventions can help individuals return to work. This paper reviews literature and research into CBT and occupational outcomes and considers whether a return-to-work agenda may jeopardize the therapeutic alliance which is suggested to be necessary for effective CBT. Moreover, through the use of clinical examples from our practice, we suggest ways in which employment issues might be integrated into CBT for depression and anxiety disorders. We conclude that a return-to-work agenda can be utilized during therapy while maintaining a collaborative and secure therapeutic relationship, especially, perhaps if work issues are embedded within the formulation. However, further research is needed, not only to determine whether CBT can help individuals return to work but also how CBT might best integrate a return-to-work agenda.
Long GPS coordinate time series: Multipath and geometry effects
Authors: King Matt A. , Watson Christopher S.
Published: April 2010

Within analyses of Global Positioning System (GPS) observations, unmodeled subdaily signals propagate into long‐period signals via a number of different mechanisms. In this paper, we investigate the effects of time‐variable satellite geometry and the propagation of a time‐constant unmodeled multipath signal. Multipath reflectors atH= 0.1 m, 0.2 m, and 1.5 m below the antenna are modeled, and their effects on GPS coordinate time series are examined. Simulated time series at 20 global IGS sites for 2000.0–2008.0 were derived using the satellite geometry as defined by daily broadcast orbits. We observe the introduction of time‐variable biases in the time series of up to several millimeters. The frequency and magnitude of the signal is dependent on site location and multipath source. When adopting realistic GPS observation geometries obtained from real data (e.g., including the influence of local obstructions and hardware specific tracking), we observe generally larger levels of coordinate variation. In these cases, we observe spurious signals across the frequency domain, including very high frequency abrupt changes (offsets) in addition to secular trends. Velocity biases of more than 0.5 mm/yr are evident at some sites. The propagated signal has noise characteristics that fall between flicker and random walk and shows spectral peaks at harmonics of the draconitic year for a GPS satellite (∼351 days). When a perfectly repeating synthetic constellation is used, the simulations show near‐negligible time correlated noise highlighting that subtle variations in the GPS constellation can propagate multipath signals differently over time, producing significant temporal variations in time series.
Oxidant (O3 + NO2) production processes and formation regimes in Beijing
Authors: Lu Keding , Zhang Yuanhang , Su Hang , Brauers Theo , Chou Charles C. , Hofzumahaus Andreas , Liu Shaw C. , Kita Kazuyuki , Kondo Yutaka , Shao Min , Wahner Andreas , Wang Jialin , Wang Xuesong , Zhu Tong
Published: April 2010

For CareBeijing‐2006, two sites were established in urban and suburban regions of Beijing in summer 2006. Observations of O3 and its precursors together with meteorological parameters at both sites are presented. Gross ozone production rate P(O3) and sensitivity to nitric oxides (NOx) and volatile organic compounds (VOCs) were investigated using an observation‐based photochemical box model (OBM). P(O3) varied from nearly zero to 120 and 50 ppb h−1 for urban and suburban sites, respectively. These rates were greater than the accumulation rates of the observed oxidant (O3 + NO2) concentrations. The O3 episodes typically appeared under southerly wind conditions with high P(O3), especially at the urban site. Sensitivity studies with and without measured nitrous acid (HONO) as a model constraint suggested that the estimated P(O3) at both sites was strongly enhanced by radical production from HONO photolysis. Both NOx‐ and VOC‐sensitive chemistries existed over time scales from hours to days at the two sites. The variation in O3‐sensitive chemistry was relatively well explained by the ratio of the average daytime total VOC reactivity (kTVOC) to NO, with the transition chemistry corresponding to a kTVOC/NO value of 2–4 s−1 ppb−1. Pronounced diurnal variations in the O3 production regime were found. In the morning, conditions were always strongly VOC‐limited, while in the afternoon, conditions were variable for different days and different sites. The model‐calculated results were tested by measurements of H2O2, HNO3, total OH reactivity, and HOx radicals. The OBM was generally capable of correctly simulating the levels of P(O3), although it might tend to overpredict the VOC‐sensitive chemistry.
Stochastic modeling of soil salinity
Authors: Suweis S. , Rinaldo A. , Van der Zee S. E. A. T. M. , Daly E. , Maritan A. , Porporato A.
Published: April 2010

A minimalist stochastic model of primary soil salinity is proposed, in which the rate of soil salinization is determined by the balance between dry and wet salt deposition and the intermittent leaching events caused by rainfall events. The long term probability density functions of salt mass and concentration are found by reducing the coupled soil moisture and salt mass balance equation to a single stochastic differential equation driven by multiplicative Poisson noise. The novel analytical solutions provide insight on the interplay of the main soil, plant and climate parameters responsible for long‐term soil salinization. In particular, they show the existence of two distinct regimes, one where the mean salt mass remains nearly constant (or decreases) with increasing rainfall frequency, and another where mean salt content increases markedly with increasing rainfall frequency. As a result, relatively small reductions of rainfall in drier climates may entail dramatic shifts in long‐term soil salinization trends, with significant consequences e.g. for climate change impacts on rain‐fed agriculture.
Projection of changes in tropical cyclone activity and cloud height due to greenhouse warming: Global cloud‐system‐resolving approach
Authors: Yamada Yohei , Oouchi Kazuyoshi , Satoh Masaki , Tomita Hirofumi , Yanase Wataru
Published: April 2010

Tropical cyclone (TC) activity change due to global warming (GW) has been investigated using general circulation models. However, they involve uncertainty in treating the ensemble effects of deep convections. Here we sidestep such uncertainty by using a global cloud‐system‐resolving model (GCRM) and assess TC changes with a time‐slice experiment for the present‐day and future GW experiments spanning 5 months each. The results support the Intergovernmental Panel on Climate Change Fourth Assessment Report; reduction in global frequency but increase in more intense TCs. Consistent with recent studies, frequency is reduced over the North Atlantic due to intensified vertical wind shear. Over the Pacific, frequency is almost unchanged and the genesis location shifts eastward under the prescribed El‐Niño like sea surface temperature change. With the GCRM's advantage of representing mesoscale properties, we find that the cloud height becomes taller for more intense TCs and that this relationship is strengthened with GW.
Ultra‐shallow seismic imaging of the top of the saturated zone
Authors: Sloan Steven D. , Tsoflias Georgios P. , Steeples Don W.
Published: April 2010

We collected ultra‐shallow seismic‐reflection data to image the near‐surface stratigraphy of a Kansas River point bar. We were successful in identifying a discontinuous clay layer and the top of the saturated zone at depths of 0.95 and 1.4 m. Seismic walkaway data collected using various .22‐caliber ammunition show that decreased source energy is necessary to generate higher frequencies and prevent clipping of critical near‐offset traces needed to identify ultra‐shallow reflections. The seismic reflections exhibited average normal moveout velocities of 180–195 m/s with dominant frequencies of 200–450 Hz. Coincident subsurface features were also imaged using 200‐MHz ground‐penetrating radar. This study presents the shallowest seismic reflection from the top of the saturated zone reported in the literature to date and further demonstrates the potential of using seismic‐reflection methods for ultra‐shallow imaging of the subsurface as a stand‐alone tool or in conjunction with other high‐resolution geophysical techniques.
Host‐cell lipid rafts: a safe door for micro‐organisms?
Authors: Vieira Flávia Sarmento , Corrêa Gladys , Einicker‐Lamas Marcelo , Coutinho‐Silva Robson
Published: April 2010

The lipid raft hypothesis proposed that these microdomains are small (10–200 nM), highly dynamic and enriched in cholesterol, glycosphingolipids and signalling phospholipids, which compartmentalize cellular processes. These membrane regions play crucial roles in signal transduction, phagocytosis and secretion, as well as pathogen adhesion/interaction. Throughout evolution, many pathogens have developed mechanisms to escape from the host immune system, some of which are based on the host membrane microdomain machinery. Thus lipid rafts might be exploited by pathogens as signalling and entry platforms. In this review, we summarize the role of lipid rafts as players in the overall invasion process used by different pathogens to escape from the host immune system.
Transient receptor potential channels and vascular function
Authors: Earley Scott , Brayden Joseph E.
Published: April 2010

TRP (transient receptor potential) channels play important roles in the regulation of normal and pathological cellular function. In the vasculature, TRP channels are present both in ECs (endothelial cells) and vascular SMCs (smooth muscle cells) and contribute to vasomotor control mechanisms in most vascular beds. Vascular TRP channels are activated by various stimuli, such as mechanical perturbation, receptor activation and dietary molecules. Some of the specific roles of these channels in normal and impaired vascular function have emerged in recent years and include participation in vascular signalling processes, such as neurotransmission, hormonal signalling, NO production, myogenic tone and autoregulation of blood flow, thermoregulation, responses to oxidative stress and cellular proliferative activity. Current research is aimed at understanding the interactions of TRP channels with other vascular proteins and signalling mechanisms. These studies should reveal new targets for pharmacological therapy of vascular diseases, such as hypertension, ischaemia and vasospasm, and vascular proliferative states.
Relationship of Word- and Sentence-Level Working Memory to Reading and Writing in Second, Fourth, and Sixth Grade
Authors: Berninger Virginia W. , Abbott Robert D. , Swanson H. Lee , Lovitt Dan , Trivedi Pam , Lin Shin-Ju (Cindy) , Gould Laura , Youngstrom Marci , Shimada Shirley , Amtmann Dagmar
Published: April 2010

Purpose

The purpose of this study was to evaluate the contribution of working memory at the word and sentence levels of language to reading and writing outcomes.

Method

Measures of working memory at the word and sentence levels, reading and writing, were administered to 2nd (N= 122), 4th (N= 222), and 6th (N= 105) graders. Structural equation modeling was used to evaluate whether the 2 predictor working memory factors contributed unique variance beyond their shared covariance to each of 5 outcome factors: handwriting, spelling, composing, word reading, and reading comprehension.

Results

At each grade level, except for handwriting and composing in 6th grade, the word-level working memory factor contributed unique variance to each reading and writing outcome. The text-level working memory factor contributed unique variance to reading comprehension in 4th and 6th grade.

Discussion

The clinical significance of these findings for assessment and intervention is discussed.
The Early Years of Language, Speech, and Hearing Services in U.S. Schools
Authors: Duchan Judith Felson
Published: April 2010

Purpose

This article focuses on various aspects of the beginnings of speech therapy offerings in America’s public schools. It traces the pioneering professionals and significant milestones associated with diagnostic and therapy practices during the late 19th and early 20th century. The aim is to uncover the neglected history of public school speech therapy practices and to show how the practices of yesterday compare with those of today.

Method

Historical documents were analyzed to discover the key contributors and locations of the first public school speech-pathology programs. The analysis also traces the populations that were served and the professional training of the early practitioners, as well as their therapy and service delivery practices.

Conclusions

Between 1895 and 1921, most of the major cities in the United States had hired their first speech clinicians. Between 1921 and 1930, many cities expanded their programs and were hiring supervisors to coordinate these services. These early clinicians carved out some now-familiar practices. Comparing what they did and when and how they did it with today’s practices can offer school clinicians of today a sense of their own history and identity. Such an understanding can also provide insights about some of today’s taken-for-granted practices.
The effect of crystal geometry on the formation and crack development in molybdenum single crystals
Authors: Tamayo-Meza Pedro A. , Yermishkin Viacheslav , Schabes-Retchkiman Pablo
Published: April 2010

The systematic study of the defect structure evolution in single crystal specimens deformed in situ in the high voltage transmission electron microscope (HVTEM) was started around 1977 in the Baikov Metallurgy Institute of the USSR Academy of Sciences. All the experience gathered for the past 30 years has set up the basis for the determination of the way that metals adapt to the different physical factors inside the HVTEM column. In the present work the detailed phenomenology of the generation and propagation process of cracks in single crystals of Mo with different crystallographic orientations as well as the kinetics of opening of primary and secondary cracks and the tip evolution for cracks with different dislocation generation sources is presented.
An operator approach to the Al-Salam–Carlitz polynomials
Authors: Chen William Y. C. , Saad Husam L. , Sun Lisa H.
Published: April 2010

We present an operator approach to Rogers-type formulas and Mehler’s formula for the Al-Salam–Carlitz polynomials Un(x,y,a;q). By using the q-exponential operator, we obtain a Rogers-type formula, which leads to a linearization formula. With the aid of a bivariate augmentation operator, we get a simple derivation of Mehler’s formula due to Al-Salam and Carlitz [“Some orthogonal q-polynomials,” Math. Nachr. 30, 47 (1965)]. By means of the Cauchy companion augmentation operator, we obtain an equivalent form of Mehler’s formula. We also give several identities on the generating functions for products of the Al-Salam–Carlitz polynomials, which are extensions of the formulas for the Rogers–Szegö polynomials.
Effect of the dipole–dipole interaction on the low-temperature magnetism of linear spin chains
Authors: Zhuravlev A. V. , Krygin I. M.
Published: April 2010

The magnetic dipole–dipole interaction in a linear chain of spins S=1∕2 with uniaxial exchange anisotropy gives raise to evolution of the system of energy levels. As the magnetic dipole interaction increases, the fastest decrease of the energy of the system is observed for a level with the maximum modulus of the spin of the system. For sufficiently large ratio of the dipole–dipole contribution to the exchange a transition occurs between the spin-gap states—antiferromagnetic and ferromagnetic. An extremely sharp change of the mean-square spin of the system at low temperatures (T<10−3J∕k) followed by a “plateau” in the temperature dependence is characteristic for a narrow neighborhood of the point at which the type of ground state changes.
Magnetic and magnetoresistive properties of sodium-substituted lanthanum manganites
Authors: Tovstolytkin A. I. , Tsmots’ V. M. , Pan’kiv L. I. , Litovchenko P. G. , Pan’kiv I. S.
Published: April 2010

The magnetic, electric, and magnetoresistive properties of bulk samples of La1−xNaxMnO3±δ (x=0.08–0.16) are studied. It is shown that at low temperatures all samples are ferromagnetic and the temperature of the transition from the paramagnetic into the ferromagnetic state increases with increasing sodium content. It is found that the saturation magnetization reaches its maximum value, close to that computed theoretically, in samples with x=0.12. A deviation of x from 0.12 decreases the saturation magnetization and broadens the magnetic transition. Analysis of the behavior of the magnetoresistance shows that there exists, together with the ferromagnetic conducting phase, a disordered weakly conducting phase, the volume fraction of the latter increasing as x deviates away from 0.12. The characteristic behavior of the magnetic and magnetoresistive properties of La1−xNaxMnO3±δ samples are tied to the particulars of the evolution of the chemical composition and defectiveness of the samples as a function of the sodium concentration.
Magnetic state of nanocrystals of Zn-substituted magnetite
Authors: Ol’khovik L. P. , Sizova Z. I. , Tkachenko N. V. , Shein V. O. , Kalinin P. S. , Khats’ko E. N. , Levitin E. Ya. , Koval’ A. A.
Published: April 2010

A system of ultrasmall nanocrystals of zinc-substituted magnetite has been synthesized by chemical condensation. Indications of a transition of the particles into a superparamagnetic state have been found by two methods—1) measurements of the temperature dependence of the magnetization in the temperature interval 4.2–250K for fixed values of the external magnetic field from 10Oeto2kOe and 2) the major hysteresis loop at 300K. The dependence of the blocking temperature on the magnetic field strength is obtained.
Quantum oscillations of resistivity in bismuth nanowires
Authors: Condrea E. , Gilewski A.
Published: April 2010

The influence of uniaxial deformation on the transport properties of bismuth wires is studied in a wide range of temperatures. Measurements of the resistance of bismuth nanowires with several diameters and different quality reveal oscillations in the strain dependence of the resistance for uniaxial strain at T=4.2K. The amplitude of oscillations is significant (38%) at helium temperature and becomes smeared at T=77K. The oscillations observed are due to the quantum size effect. By evaluating the period of oscillations we are able to identify the groups of carriers involved in transport. The computed periods of 42.2 and 25.9nm are approximatively in the ratio 2:1 for two experimentally observed sets of oscillations from light and heavy electrons.
Lattice parameters of CO2-Kr cryoalloys
Authors: Danchuk V. V. , Solodovnik A. A. , Strzhemechnyĭ M. A.
Published: April 2010

The structure of the cryoalloys CO2-Kr has been studied in the entire range of relative concentrations by means of transmission electron diffraction. Gaseous samples were deposited from a tank at room temperature onto substrates cooled to 30K. The filling channel was thermally insulated from the cryogenic screens. An anomalous dependence of the lattice parameter a on the molar content x of krypton in the initial gas mixture was observed; specifically, the function a(x) contains a section which can be regarded as a minimum to within the limits of error. The maximum solubility of the krypton in the carbon dioxide crystal is 38mol.%, and the solubility of CO2 in a Kr crystal is low. The experimental data taken together give us a basis for supposing that the phase composition as a function of x has the following regions: 1) 0⩽x⩽0.38—regular solution of Kr in CO2; 0.38⩽x⩽0.6—mixture of a regular solution with critical concentration xcr=0.38 and nano inclusions of almost pure Kr; 3) 0.6⩽x⩽1—mixture of almost pure Kr with nano inclusions of a solution with xcr. A theoretical explanation is given for the anomalous behavior of the function a(x) for x≲20mol.%; the explanation is based on a cluster model and takes account of three mechanisms of interaction of Kr clusters with the crystalline environment of CO2.
Spin-wave fluctuations in ferrimagnetic MgxFe3−xO4 nanoparticles
Authors: Franco A. , Zapf V. S. , Barbeta V. B. , Jardim R. F.
Published: April 2010

We have performed a systematic study of the magnetic properties of a series of ferrimagnetic nanoparticles of MgxFe3−xO4 (0.8≤x≤1.5) prepared by the combustion reaction method. The magnetization data can be well fitted by Bloch’s law with T3/2. Bloch’s constant B determined from the fitting procedure was found to increase with Mg content x from ∼3.09×10−5 K−3/2 for x=0.8 to 6.27×10−5 K−3/2 for x=1.5. The exchange integral JAB and the spin-wave stiffness constant D of MgxFe3−xO4 nanoparticles were also determined as ∼0.842 and 0.574 meV and 296 and 202 meV Å2 for specimens with x=0.8 and 1.5, respectively. These results are discussed in terms of cation redistribution among A and B sites on these nanostructured spinel ferrites.
Theoretical study of the dynamics of F+alkanethiol self-assembled monolayer hydrogen-abstraction reactions
Authors: Layfield Joshua P. , Troya Diego
Published: April 2010

The dynamics of the reactions of F atoms with octanethiol self-assembled monolayers (SAMs) has been studied using theoretical methods. F+SAM classical trajectories have been propagated directly using a quantum-mechanics (QM) /molecular-mechanics scheme in which the QM portion is described using a specific-reaction-parameters (SRP) semiempirical Hamiltonian. This SRP Hamiltonian has been derived using ab initio information of model gas-phase F+alkane reactions and its accuracy has been calibrated via comparison of the result of direct-dynamics calculations with available experiments on the F+CH4→HF+CH3 and F+C2H6→HF+C2H5 reactions. The F+SAM calculations are used to analyze HF product-energy distributions at collision energies ranging from 0.80 to 11.53 kcal mol−1 and 0°, 30°, and 60° incident angles with respect to the surface normal. The calculations show that while the HF product is vibrationally excited, it desorbs translationally and rotationally cold at all collision energies and incident angles explored. The calculated results shed light into recent experiments of F-atom reactions with liquid alkane surfaces by providing mechanistic understanding of the factors that govern the amount of energy deposited into the various degrees of freedom of the HF product. Specifically, examination of the dynamics of postreaction HF collisions with the surface shows the role that secondary collisions play in quenching rotational and translational excitation of HF before desorption from the surface.
Structure and binding in crystals of cagelike molecules: Hexamine and platonic hydrocarbons
Authors: Berland Kristian , Hyldgaard Per
Published: April 2010

In this paper, we show that first-principle calculations using a van der Waals density functional (vdW-DF) [M. Dion, H. Rydberg, E. Schröder, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004)] permit the determination of molecular crystal structure within density functional theory (DFT). We study the crystal structures of hexamine and the platonic hydrocarbons (cubane and dodecahedrane). The calculated lattice parameters and cohesion energy agree well with experiments. Further, we examine the asymptotic accounts of the van der Waals forces by comparing full vdW-DF with asymptotic atom-based pair potentials extracted from vdW-DF. The character of the binding differs in the two cases, with vdW-DF giving a significant enhancement at intermediate and relevant binding separations. We analyze consequences of this result for methods such as DFT-D and question DFT-D’s transferability over the full range of separations.
Photogeneration of charge carrier correlated with amplified spontaneous emission in single crystals of a thiophene/phenylene co-oligomer
Authors: Saeki Akinori , Seki Shu , Shimizu Yasuhiro , Yamao Takeshi , Hotta Shu
Published: April 2010

Thiophene/phenylene co-oligomers have substantial promise for the use of not only organic electronics but also organic optical devices. However, considerably less is known about the correlation between their optical and optoelectronic properties. We have investigated the charge carrier generation in 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5) single crystals by flash-photolysis time-resolved microwave conductivity (TRMC) and transient absorption spectroscopy (TAS). It was found that the dependence of photocarrier generation efficiency on excitation photon density differed from that of emission efficiency once amplified spontaneous emission (ASE) and resultant spectrally narrowed emission occur upon exposure to 355 nm. In contrast, the dependences of emission and photocarrier generation efficiencies were identical when ASE was not involved at a different excitation wavelength (193 nm). An approximated analytical solution of rate equation considering ASE or singlet-singlet annihilation was applied to the experiments, exhibiting good agreement. On the basis of TRMC, TAS, and extinction coefficient of radical cation assessed by pulse radiolysis, the minimum charge carrier mobility was estimated, without electrodes, to be 0.12 cm2 V−1 s−1. The dynamics of charge carrier and triplet excited state is discussed, accompanying with examination by time-dependent density functional theory. The present work would open the way to a deeper understanding of the fate of excited state in optically robust organic semiconducting crystals.
Quantum-classical modeling of photoisomerization of polyatomic molecules
Authors: Tranca D. C. , Neufeld A. A.
Published: April 2010

A new method, non-Markovian quantum-classical approximation (NQCA), is suggested to model the photoisomerization of polyatomic molecules. The NQCA method can be successfully applied to follow the photoisomerization process for a wide class of reacting systems, namely, those for which the time scale required for the equilibration in the phase space of the potential energy surface (PESs) is short compared to the time scale of the transitions between them. Such a situation is quite typical for the nonadiabatic transitions between the different electronic states in polyatomic molecules, where a high density of vibronic states facilitates the intramolecular vibrational energy redistribution, thus providing an efficient relaxation for the phase space distribution. The NQCA can easily be combined with molecular dynamics and quantum-chemical methods to describe the evolution of the classical degrees of freedom and the quantum part of the problem.
Relativistic self-induced transparency effect during ultraintense laser interaction with overdense plasmas: Why it occurs and its use for ultrashort electron bunch generation
Authors: Eremin V. I. , Korzhimanov A. V. , Kim A. V.
Published: April 2010

A novel explanation of the relativistic self-induced transparency effect during superintense laser interaction with an overdense plasma is proposed. It was studied analytically and verified with direct modeling by particle-in-cell simulations. Based on this treatment, a method of ultrashort high-energy electron bunch generation with durations on a femtosecond time scale is also proposed and studied via numerical simulation.
Characterization of electrowetting processes through force measurements
Authors: Crane Nathan B. , Mishra Pradeep , Volinsky Alex A.
Published: April 2010

A new method of characterizing electrowetting is presented. In this method, the electrowetting actuation forces are measured rather than the contact angle. The forces on the liquid are measured by trapping a droplet between a flat nanoindenter tip and the test substrate. When voltage is applied to electrodes in the substrate, lateral and normal forces are exerted on the tip and measured by the nanoindenter transducer. Proper selection of the tip geometry permits direct prediction of the resulting in-plane lateral forces using analytical formulas derived from the Young–Lippmann equation. Experimental results show good agreement with both analytical and numerical predictions. Numerical modeling using SURFACE EVOLVER shows that the lateral forces are relatively insensitive to most alignment errors and that the analytical model is most accurate when the flat tip is close to the substrate. Evaporation of the test liquid can introduce modest errors in long measurements, but compensation methods are presented. As the droplet undergoes almost no movement, the fluid dynamics have minimal impact on the measured forces and transient electrowetting events are readily detected. Experimental results show significant response at frequencies up to 40 Hz. This setup is useful in measuring electrowetting responses at high speeds and in measuring system degradation processes.
Compression-induced transformation of aldehydes into polyethers: A first-principles molecular dynamics study
Authors: Mosey Nicholas J.
Published: April 2010

First-principles molecular dynamics simulations are used to investigate the behavior of bulk acetaldehyde (MeCHO) under conditions of increasing pressure. The results demonstrate that increasing pressure causes the aldehydes to polymerize, yielding polyethers through a process involving the rapid formation of CO bonds between multiple neighboring MeCHO molecules. Attempts to induce polyether formation at different densities through the application of geometric constraints show that polymerization occurs only once a critical density of ∼1.7 g/cm3 has been reached. The results of simulations performed at several different temperatures are also consistent with a process that is induced by reaching a critical density. The origins of this effect are rationalized in terms of the structural requirements for the formation of CO bonds between multiple MeCHO molecules in rapid succession. Specifically, the collective formation of CO bonds requires the typical distance between the sp2 carbon atoms and oxygen atoms in neighboring MeCHO molecules to reach a value of approximately 2.5 Å. Radial distribution functions calculated at different densities show that this structural requirement is reached when the density is near the observed threshold. The observed reaction may be useful in the context of lubrication, with polyethers being effective lubricants and the extreme conditions experienced in sliding contacts providing the ability to reach the high densities needed to induce the reaction. In this context, the calculations indicate that polyether formation is associated with significant energy dissipation, while energy dissipation is minimal once the polyethers are formed. Furthermore, the polyethers are stable with respect to multiple compression/decompression cycles and pressures of at least 60 GPa.
Application of the R-matrix method to photoionization of molecules
Authors: Tashiro Motomichi
Published: April 2010

The R-matrix method has been used for theoretical calculation of electron collision with atoms and molecules for long years. The method was also formulated to treat photoionization process, however, its application has been mostly limited to photoionization of atoms. In this work, we implement the R-matrix method to treat molecular photoionization problem based on the UK R-matrix codes. This method can be used for diatomic as well as polyatomic molecules, with multiconfigurational description for electronic states of both target neutral molecule and product molecular ion. Test calculations were performed for valence electron photoionization of nitrogen (N2) as well as nitric oxide (NO) molecules. Calculated photoionization cross sections and asymmetry parameters agree reasonably well with the available experimental results, suggesting usefulness of the method for molecular photoionization.
Lasing effect in a hybrid dye-doped biopolymer and photochromic polymer system
Authors: Mysliwiec Jaroslaw , Sznitko Lech , Sobolewska Anna , Bartkiewicz Stanislaw , Miniewicz Andrzej
Published: April 2010

We investigate an amplified spontaneous emission phenomenon and lasing in a two-layer system: a layer of modified deoxyribonucleic acid (DNA) polymeric matrix containing dye which is superimposed on a periodic relief structure formed in photochromic polymer. The luminescent layer was prepared from DNA blended with cationic surfactant molecule cetyltrimethyl-ammonium chloride (CTMA) and a Rhodamine (Rh6G) laser dye. This layer covered a specially designed photochromic polymer layer in which a surface relief grating was inscribed by holographic method in order to form a Bragg reflector for photons. Thin film of the DNA-CTMA:Rh6G/photochromic polymer was excited with pulsed laser.
Effect of doping on the mid-infrared intersubband absorption in GaN/AlGaN superlattices grown on Si(111) templates
Authors: Kandaswamy P. K. , Machhadani H. , Kotsar Y. , Sakr S. , Das A. , Tchernycheva M. , Rapenne L. , Sarigiannidou E. , Julien F. H. , Monroy E.
Published: April 2010

We report on the effect of Si doping on the mid-infrared intersubband absorption in GaN/AlGaN superlattices. For increasing doping levels, interband luminescence displays a blueshift and a broadening of the band edge caused by the screening of the internal electric field and band-filling effects. The intersubband absorption energy is mainly governed by many-body effects like exchange interaction and depolarization shift, which increase the e1–e2 subband separation. The ISB blueshift induced by many-body effects can be more than 50% of the e1–e2 transition energy.
Reproducible trajectory on subnanosecond spin-torque magnetization switching under a zero-bias field for MgO-based ferromagnetic tunnel junctions
Authors: Aoki Tatsuya , Ando Yasuo , Oogane Mikihiko , Naganuma Hiroshi
Published: April 2010

One of the features of spin-transfer torque (STT)-based magnetic random access memories (spin-RAMs) is a fast write cycle; however, switching properties in the subnanosecond regime for MgO-based magnetic tunnel junctions (MTJs) are still unclear. In this work, we demonstrated subnanosecond magnetization switching by STT for MgO-based MTJs. We also discuss the thermal effect on subnanosecond STT switching, as well as the subnanosecond pulse width that is dependent on the remarkable plateau that switching probability has under a zero-bias field.
Shubnikov–de Haas and Aharonov Bohm effects in a graphene nanoring structure
Authors: Yoo Jai Seung , Park Yung Woo , Skákalová Viera , Roth Siegmar
Published: April 2010

We observed the Shubnikov–de Haas and the Aharonov Bohm oscillations in a graphene nanoring structure of 1 μm in diameter and with a 125 nm channel width. We found a separation of 2ΔVg=17.5 V between electron and hole Landau levels in the plot of longitudinal resistance as a function of gate voltage and magnetic field. This separation can be understood as a result of the transport gap, ΔVt=20 V, in the density of state. The Aharonov Bohm effect was observed in magnetoconductance with poor visibility because of the short phase coherence length of the graphene nanoring structure.
Communications: Complete description of re-entrant phase behavior in a charge variable colloidal model system
Authors: Wette Patrick , Klassen Ina , Holland-Moritz Dirk , Herlach Dieter M. , Schöpe Hans Joachim , Lorenz Nina , Reiber Holger , Palberg Thomas , Roth Stephan V.
Published: April 2010

In titration experiments with NaOH, we have determined the full phase diagram of charged colloidal spheres in dependence on the particle density n, the particle effective charge Zeff and the concentration of screening electrolyte c using microscopy, light and ultrasmall angle x-ray scattering (USAXS). For sufficiently large n, the system crystallizes upon increasing Zeff at constant c and melts upon increasing c at only slightly altered Zeff. In contrast to earlier work, equilibrium phase boundaries are consistent with a universal melting line prediction from computer simulation, if the elasticity effective charge is used. This charge accounts for both counterion condensation and many-body effects.
Simulating thermal motion in crystalline phase-I ammonia
Authors: Reilly Anthony M. , Habershon Scott , Morrison Carole A. , Rankin David W. H.
Published: April 2010

Path-integral molecular dynamics have been used to simulate the phase-I crystalline form of ammonia, using an empirical force field. This method allows quantum-mechanical effects on the average geometry and vibrational quantities to be evaluated. When these are used to adjust the output of a high-temperature density functional theory simulation, the results are consistent with those given by the most recent structural refinement based on powder neutron diffraction data. It is clear that the original refinement overestimated thermal motion, and therefore also overestimated the equilibrium N–{H/D} bond length.
Estimation of the Heat Capacities of Organic Liquids as a Function of Temperature using Group Additivity. I. Hydrocarbon Compounds
Authors: Růžička Vlastimil , Domalski Eugene S.
Published: April 2010

A second-order group additivity method has been developed for the estimation of the heat capacity of liquid hydrocarbons as a function of temperature in the range from the melting temperature to the normal boiling temperature. The temperature dependence of group contributions and structural corrections has been represented by a polynomial expression. The adjustable parameters in the polynomials have been calculated using a weighted least squares minimization procedure. Recommended heat capacities from a large compilation of critically evaluated data that contains over 1300 organic liquids served as a database both for the development and testing of the method.
Estimation of the Heat Capacities of Organic Liquids as a Function of Temperature using Group Additivity. II. Compounds of Carbon, Hydrogen, Halogens, Nitrogen, Oxygen, and Sulfur
Authors: Růžička Vlastimil , Domalski Eugene S.
Published: April 2010

A second-order group additivity method has been developed for the estimation of the heat capacity of liquid organic compounds containing carbon, hydrogen, halogens, nitrogen, oxygen, and sulfur. The method permits the estimation of the heat capacity as a function of temperature in the range from the melting temperature to the normal boiling temperature. Group contributions and structural corrections have been made temperature dependent by the use of a polynomial expression. The adjustable parameters in the polynomials have been calculated using a weighted least squares minimization procedure. This work has drawn information for both the development and testing of the method from a large compilation of critically evaluated heat capacity data for over 1300 organic liquids.
Developmental constraint on the evolution of marsupial forelimb morphology
Authors: Cooper W. James , Steppan Scott J.
Published: April 2010

Compared with the placental mammals, marsupials are born at an almost embryonic stage, but nearly all of these neonates immediately climb or crawl to one of their mother’s teats using precociously developed forelimbs. Marsupial adults also exhibit limited forelimb shape diversity relative to the members of their sister group. That the functional requirements of this natal climb have imposed a developmental constraint on marsupial forelimb evolution represents a compelling and widely accepted hypothesis, yet its resulting predictions for the comparative patterns of mammal limb shape diversity have never been tested. In order to perform such tests we conducted extensive taxonomic sampling of mammal limb morphology (including fossil specimens), and then examined these data using morphometric methods, non-parametric analyses of anatomical disparity, and phylogenetic comparative analyses of evolutionary rates. Our results strongly support the constraint hypothesis, and indicate that the highly significant differences between marsupial and placental forelimb shape diversity has been strongly influenced by different rates of morphological evolution among the distal forelimb elements in these two important mammal lineages.
Evidence of recent population expansion in the field cricket Teleogryllus commodus
Authors: Cairns Kylie M. , Wolff Jonci N. , Brooks Robert C. , Ballard J. William O.
Published: April 2010

The patterns of intraspecific genetic variation can be driven by large-scale environmental events or smaller-scale phenomena such as land clearing. In Australia, European farming techniques have altered the landscape by increasing the amount of arable farmland. We hypothesised that this increase in farmland would result in a concomitant increase in the effective population size of the black field cricket (Teleogryllus commodus). To test our hypothesis, we investigated genetic variation in 1350 bp of mitochondrial mtDNA and in two nuclear encoded loci, hexokinase and elongation factor 1-α, from 20 crickets collected at Smiths Lake, New South Wales. Molecular variation in T. commodus was characterised by an over-representation of singleton mutations (negative Tajima’s D and Fu and Li’s D) in all loci studied. Further, HKA tests do not suggest that selection is acting on any one gene. Combined, these data support the hypothesis that population expansion is the force driving molecular variation in T. commodus. If an increase in agricultural habitats is the cause of population expansion in T. commodus we hypothesise greater genetic subdivision in natural than farmland habitats. An alternative possibility is that the effective geographical range of the species has increased but the density at a given site remains unchanged.
Proliferation of anomalous symmetries in colloidal monolayers subjected to quasiperiodic light fields
Authors: Mikhael Jules , Schmiedeberg Michael , Rausch Sebastian , Roth Johannes , Stark Holger , Bechinger Clemens
Published: April 2010

Quasicrystals provide a fascinating class of materials with intriguing properties. Despite a strong potential for numerous technical applications, the conditions under which quasicrystals form are still poorly understood. Currently, it is not clear why most quasicrystals hold 5- or 10-fold symmetry but no single example with 7- or 9-fold symmetry has ever been observed. Here we report on geometrical constraints which impede the formation of quasicrystals with certain symmetries in a colloidal model system. Experimentally, colloidal quasicrystals are created by subjecting micron-sized particles to two-dimensional quasiperiodic potential landscapes created by
n
 = 5 or seven laser beams. Our results clearly demonstrate that quasicrystalline order is much easier established for
n
 = 5 compared to
n
 = 7. With increasing laser intensity we observe that the colloids first adopt quasiperiodic order at local areas which then laterally grow until an extended quasicrystalline layer forms. As nucleation sites where quasiperiodicity originates, we identify highly symmetric motifs in the laser pattern. We find that their density strongly varies with
n
and surprisingly is smallest exactly for those quasicrystalline symmetries which have never been observed in atomic systems. Since such high-symmetry motifs also exist in atomic quasicrystals where they act as preferential adsorption sites, this suggests that it is indeed the deficiency of such motifs which accounts for the absence of materials with e.g., 7-fold symmetry.
Recapitulation of endochondral bone formation using human adult mesenchymal stem cells as a paradigm for developmental engineering
Authors: Scotti Celeste , Tonnarelli Beatrice , Papadimitropoulos Adam , Scherberich Arnaud , Schaeren Stefan , Schauerte Alexandra , Lopez-Rios Javier , Zeller Rolf , Barbero Andrea , Martin Ivan
Published: April 2010

Mesenchymal stem/stromal cells (MSC) are typically used to generate bone tissue by a process resembling intramembranous ossification, i.e., by direct osteoblastic differentiation. However, most bones develop by endochondral ossification, i.e., via remodeling of hypertrophic cartilaginous templates. To date, endochondral bone formation has not been reproduced using human, clinically compliant cell sources. Here, we aimed at engineering tissues from bone marrow-derived, adult human MSC with an intrinsic capacity to undergo endochondral ossification. By analogy to embryonic limb development, we hypothesized that successful execution of the endochondral program depends on the initial formation of hypertrophic cartilaginous templates. Human MSC, subcutaneously implanted into nude mice at various stages of chondrogenic differentiation, formed bone trabeculae only when they had developed in vitro hypertrophic tissue structures. Advanced maturation in vitro resulted in accelerated formation of larger bony tissues. The underlying morphogenetic process was structurally and molecularly similar to the temporal and spatial progression of limb bone development in embryos. In particular, Indian hedgehog signaling was activated at early stages and required for the in vitro formation of hypertrophic cartilage. Subsequent development of a bony collar in vivo was followed by vascularization, osteoclastic resorption of the cartilage template, and appearance of hematopoietic foci. This study reveals the capacity of human MSC to generate bone tissue via an endochondral program and provides a valid model to study mechanisms governing bone development. Most importantly, this process could generate advanced grafts for bone regeneration by invoking a “developmental engineering” paradigm.
Some consequences of reflection on the approachability ideal
Authors: Sharon Assaf , Viale Matteo
Published: April 2010

We study the approachability ideal

I

[

κ
+

]

\mathcal {I}[\kappa ^+]

in the context of large cardinals and properties of the regular cardinals below a singular

κ
\kappa

. As a guiding example consider the approachability ideal

I

[

ℵ

ω
+
1

]

\mathcal {I}[\aleph _{\omega +1}]

assuming that

ℵ
ω

\aleph _\omega

is a strong limit. In this case we obtain that club many points in

ℵ

ω
+
1

\aleph _{\omega +1}

of cofinality

ℵ
n

\aleph _n

for some

n
>
1

n>1

are approachable assuming the joint reflection of countable families of stationary subsets of

ℵ
n

\aleph _n

. This reflection principle holds under

M
M

\mathsf {MM}

for all

n
>
1

n>1

and for each

n
>
1

n>1

is equiconsistent with

ℵ
n

\aleph _n

being weakly compact in

L
L

. This characterizes the structure of the approachability ideal

I

[

ℵ

ω
+
1

]

\mathcal {I}[\aleph _{\omega +1}]

in models of

M
M

\mathsf {MM}

. We also apply our result to show that the Chang conjecture

(

κ
+

,
κ
)
↠
(

ℵ
2

,

ℵ
1

)

(\kappa ^+,\kappa )\twoheadrightarrow (\aleph _2,\aleph _1)

fails in models of

M
M

\mathsf {MM}

for all singular cardinals

κ
\kappa

.
The Bochner-Schoenberg-Eberlein property for commutative Banach algebras, especially Fourier and Fourier-Stieltjes algebras
Authors: Kaniuth Eberhard , Ülger Ali
Published: April 2010

The classical Bochner-Schoenberg-Eberlein theorem characterizes the continuous functions on the dual group of a locally compact abelian group

G
G

which arise as Fourier-Stieltjes transforms of elements of the measure algebra

M
(
G
)

M(G)

of

G
G

. This has led to the study of the algebra of BSE-functions on the spectrum of an arbitrary commutative Banach algebra and of the concept of a BSE-algebra as introduced by Takahasi and Hatori. Since then BSE-algebras have been studied by several authors. In this paper we investigate BSE-algebras in the general context on the one hand and, on the other hand, we specialize to Fourier and Fourier-Stieltjes algebras of locally compact groups.