bluuebunny/crossref_metadata_2025 huggingface dataset:
If formulation is the heart of cognitive behavioural therapy, does this heart rule the head of CBT therapists?
Authors: Zivor Michael , Salkovskis Paul M. , Oldfield Victoria B.
Published: August 2013

Cognitive behavioural therapy (CBT) is an empirically grounded approach which typically relies on formulation to guide the shape and course of therapy. Cognitive formulation is widely advocated but poorly understood at an empirical level. This study aimed to characterize how clinicians understand the structure and uses of formulation and how they report on using it in their clinical practice relative to an expert reference group. A total of 124 clinicians in routine clinical practice completed a questionnaire, which assessed their clinical use and understanding of formulation. For some aspects of the questionnaire a comparison with a reference group, 15 highly specialist CBT therapists, was used. High levels of self-rated expertise were noted and at levels comparable to that of the highly specialist group. Participants rated themselves as less capable in terms of their formulation skills relative to their self-rating in CBT overall. Formulation is typically rated as important by those with some professional commitment to CBT. There may be some gaps in the way formulation is applied in clinical practice that should be addressed at the level of training and supervision.
The role of business in armed violence reduction and prevention
Authors: Wennmann Achim
Published: August 2013

This article looks at business activities in violent and fragile environments through an armed violence lens and explores the role of business in armed violence reduction and prevention (AVRP) strategies. The article argues that the transformation of armed violence patterns over the last decade requires a new optic on a subject that has traditionally been discussed in the context of ‘business and peace’ or ‘business and conflict’, and of armed violence related to inter- or intra-state armed conflict. The article sets out to better understand how different constituencies have dealt with the role of the private sector in reducing armed violence, and to connect the dots between various scholarly and practice communities to identify entry points for AVRP strategies across sectors and institutions. The article suggests that such entry points exist in relation to the costing of armed violence and civic observatories.
Genetic Architecture of the Pro-Inflammatory State in an Extended Twin-Family Design
Authors: Neijts Melanie , van Dongen Jenny , Kluft Cornelis , Boomsma Dorret I. , Willemsen Gonneke , de Geus Eco J. C.
Published: August 2013

In this study we examined the genetic architecture of variation in the pro-inflammatory state, using an extended twin-family design. Within the Netherlands Twin Register Biobank, fasting Tumor Necrosis Factor-α (TNF-α), Interleukin-6 (IL-6), C-Reactive Protein (CRP), and fibrinogen levels were available for 3,534 twins, 1,568 of their non-twin siblings, and 2,227 parents from 3,095 families. Heritability analyses took into account the effects of current and recent illness, anti-inflammatory medication, female sex hormone status, age, sex, body mass index, smoking status, month of data collection, and batch processing. Moderate broad-sense heritability was found for all inflammatory parameters (39%, 21%, 45%, and 46% for TNF-α, IL-6, CRP and fibrinogen, respectively). For all parameters, the remaining variance was explained by unique environmental influences and not by environment shared by family members. There was no resemblance between spouses for any of the inflammatory parameters, except for fibrinogen. Also, there was no evidence for twin-specific effects. A considerable part of genetic variation was explained by non-additive genetic effects for TNF-α, CRP, and fibrinogen. For IL-6, all genetic variance was additive. This study may have implications for future genome-wide association studies by setting a clear numerical target for genome-wide screens that aim to find genetic variants regulating the levels of these pro-inflammatory markers.
An Experimental Validation Method for Questioning Techniques That Assess Sensitive Issues
Authors: Moshagen Morten , Hilbig Benjamin E. , Erdfelder Edgar , Moritz Annie
Published: August 2013

Studies addressing sensitive issues often yield distorted prevalence estimates due to socially desirable responding. Several techniques have been proposed to reduce this bias, including indirect questioning, psychophysiological lie detection, and bogus pipeline procedures. However, the increase in resources required by these techniques is warranted only if there is a substantial increase in validity as compared to direct questions. Convincing demonstration of superior validity necessitates the availability of a criterion reflecting the “true” prevalence of a sensitive attribute. Unfortunately, such criteria are notoriously difficult to obtain, which is why validation studies often proceed indirectly by simply comparing estimates obtained with different methods. Comparative validation studies, however, provide weak evidence only since the exact increase in validity (if any) remains unknown. To remedy this problem, we propose a simple method that allows for measuring the “true” prevalence of a sensitive behavior experimentally. The basic idea is to elicit normatively problematic behavior in a way that ensures conclusive knowledge of the prevalence rate of this behavior. This prevalence measure can then serve as an external validation criterion in a second step. An empirical demonstration of this method is provided.
DNGR‐ing the dendritic cell lineage
Authors: Schlitzer Andreas , Ginhoux Florent
Published: August 2013

A recent groundbreaking study published in Cell provides the first ontogeny of dendritic cell (DC) development using in vivo cell tracking technology. This approach has shed light on several controversies in the DC field.
Optimisation of multi‐channel cooperative sensing in cognitive radio networks
Authors: Zhao Nan , Pu Fangling , Xu Xin , Chen Nengcheng
Published: August 2013

Cooperative spectrum sensing (CSS) is a promising technique in cognitive radio networks (CRNs) that utilises multi‐user diversity to mitigate channel instability and noise uncertainty. In this study, the relationship between ‘cooperation mechanisms’ and ‘spatial‐spectral diversity’ over multiple channels jointly sensing is investigated in the presence of an imperfect reporting channel. The multiple channels are sensed at the receiver built on the filter bank‐based multi‐carrier system. The multi‐channel CSS strategies are modelled by the introduced ‘cooperative ratio’ to balance the requirements on ‘sensing accuracy’, ‘efficiency’ and ‘overhead’, which is quantitatively characterised by the energy consumption. The target of CSS is to maximise the aggregate opportunistic throughput of secondary users (SUs) by jointly considering constraints on sensing overhead and the aggregate interference to primary users (PUs). The optimisation is divided into two sequential sub‐optimisation processes, ‘multi‐user diversity optimisation’ and ‘multi‐channel diversity optimisation’. An approach is developed from generic algorithms to solve the two sub‐problems. Numerical results show that the optimal CSS scheme is effective in improving channel utilisation for SUs with low interference to PUs. This study establishes a valuable cooperative model for the design of multi‐channel spectrum sensing algorithms in CRNs.
Phase compensation communication technique against time reversal for ultra‐wideband channels
Authors: Dezfooliyan Amir , Weiner Andrew M.
Published: August 2013

Phase compensation (PC) prefiltering is experimentally investigated for multipath channels over the frequency band spanning 2–12 GHz, a topic which to the best of the authors knowledge has not been studied in the literature on ultra‐wideband (UWB) communications. The authors emphasis is to assess the capabilities of PC compared to time reversal (TR) prefilters over indoor UWB channels regarding multipath suppression, channel hardening, noise sensitivity and high‐speed data transmission. Experiments were carried out for PC and TR prefilters in both line‐of‐sight (LOS) and non‐LOS (NLOS) environments. The multipath compression effectiveness is characterised by computing the root‐mean‐square delay spread and peak‐to‐average power ratio for actual measured channels and for the IEEE 802.15.4(a) UWB model. The authors study suggests PC outperforms TR considerably in mitigating the multipath channel dispersion. Bit‐error‐rate (BER) curves have been simulated for data rates in the range of 125–4000 Mbps based on the measured channel responses. The BER simulations suggest that while the TR performance is prohibitively saturated by its residual intersymbol interference for data rates of 500 Mbps and above (especially in NLOS), PC can be used for high‐speed data transmissions as fast as 2 Gbps in both LOS and NLOS environments.
Joint wireless communication and radar sensing systems – state of the art and future prospects
Authors: Han Liang , Wu Ke
Published: August 2013

The historical development and current state‐of‐the‐art of various joint wireless communication and radar sensing systems are reviewed and discussed in this study. Different kinds of systems are categorised according to their modulation waveforms and duplex schemes. Pros and cons of each category are highlighted. To showcase the current research advances, several demonstration systems are introduced with emphasis on proposed research contributions in this emerging area, and their performances are compared with respect to both communication and radar modes. Also, a number of challenges are identified for the near future system developments and applications.
Intra‐volume, centralised array concept for improved public‐safety communications
Authors: Young William F. , Matolak David W. , Bikhazi Nicholas , Holloway Christopher , Koepke Galen , Fielitz Helge , Wu Qiong , Zhang Qian
Published: August 2013

The author report on the testing and measurements of an intra‐volume centralised array concept suitable for public‐safety communications in buildings. The centralised array concept refers to the use of several small communication devices that are arbitrarily placed in an area and hence create a real‐time communication network. The overall concept is to use randomly located (or arbitrarily placed) wireless devices in a coordinated manner in order to increase the radio‐frequency signal level otherwise at unreachable locations. In a typical ad‐hoc network, the transmission range of any communication link in that path is limited. We seek to extend the radio‐frequency coverage within the array volume by using two or more nodes as elements of a phased array. The measurement results presented here, collected in real‐world environments, along with simulations based on real‐world data demonstrate that the centralised array technique can provide useful gain, up to 10 dB with only four elements. Both the measurements and simulations also indicate a typical gain of 2 to 6 dB, using only two elements. Analysis of the phase indicates a phase alignment of ±45° achieves within 1 dB of the maximum gain.
Study of Q‐factors of ridge and groove gap waveguide resonators
Authors: Pucci Elena , Zaman Ashraf Uz , Rajo‐Iglesias Eva , Kildal Per‐Simon , Kishk Ahmed
Published: August 2013

The gap waveguide technology for millimeter waves applications has been recently presented. The new structure is made by generating a parallel plate cut‐off region between an artificial magnetic conductor (AMC) and a metallic plate. Propagating waves will be only allowed to follow a metal ridge or groove surrounded by the AMC. The gap waveguide can be made of only metal and does not need any contact between the metal joints compared to standard waveguides. In this study, a study of Q‐factors of resonators made in ridge and groove gap waveguides are presented. The resonators are made of copper and the AMC used is a textured surface of metallic pins. Simulated and measured unloaded Qs are presented and compared with Q of a standard rectangular waveguide. High Q‐factors are measured for the prototypes presented, approaching 90–96% of the simulated values. Furthermore, it is shown how the lid of pins can easily stop the leakage loss at the joints of the circuit, which is the typical cause of reduced Q‐factor of standard waveguides at high frequency.
The Coulomb problem on a 3-sphere and Heun polynomials
Authors: Bellucci Stefano , Yeghikyan Vahagn
Published: August 2013

The paper studies the quantum mechanical Coulomb problem on a 3-sphere. We present a special parametrization of the ellipto-spheroidal coordinate system suitable for the separation of variables. After quantization we get the explicit form of the spectrum and present an algebraic equation for the eigenvalues of the Runge-Lentz vector. We also present the wave functions expressed via Heun polynomials.
Collisional excitation of CN(X2Σ+) by para- and ortho-H2: Fine-structure resolved transitions
Authors: Kalugina Yulia , Kłos Jacek , Lique François
Published: August 2013

We present a new four dimensional potential energy surface (PES) for the CN(X2Σ+)–H2 system. Both molecules were treated as rigid rotors. Potential energy was obtained from the electronic structure calculations using a partially spin-restricted coupled cluster with single, double, and perturbative triple excitations method. The four atoms were described using the augmented correlation-consistent triple zeta (aug-cc-pVTZ) basis sets augmented with mid-bond functions for improved description of van der Waals interactions. The global minimum is characterized by the well depth of 121.36 cm−1 for the linear CN⋅⋅⋅H2 structure. The zero-order corrected dissociation energies D0 are 27.73 cm−1 and 38.75 cm−1 for the complex with para- and ortho-H2, respectively. These theoretical results obtained using our new PES are in excellent agreement with experimental values [Y. Chen and M. C. Heaven, J. Chem. Phys. 109, 5171 (1998)]10.1063/1.477132. We perform fully quantum close coupling calculations of the rotationally inelastic cross sections of CN in collisions with para-H2 and ortho-H2 at low and intermediate energies. Corresponding rate coefficients were compared with experimental results of Brunet et al. [J. Chem. Phys. 116, 3617 (2002)]10.1063/1.1446033. A good agreement between theoretical and experimental results was found. Fine-structure resolved cross sections were then obtained through a recoupling technique. Significant differences exist between para- and ortho-H2 results. The propensity rules between fine-structure levels are also studied, and it is shown that the cross sections for Δj = ΔN transitions are much larger than those for Δj ≠ ΔN transitions, as expected from theoretical considerations.
Linking molecular level chemistry to macroscopic combustion behavior for nano-energetic materials with halogen containing oxides
Authors: Farley Cory W. , Pantoya Michelle L. , Losada Martin , Chaudhuri Santanu
Published: August 2013

Coupling molecular scale reaction kinetics with macroscopic combustion behavior is critical to understanding the influences of intermediate chemistry on energy propagation, yet bridging this multi-scale gap is challenging. This study integrates ab initio quantum chemical calculations and condensed phase density functional theory to elucidate factors contributing to experimentally measured high flame speeds (i.e., >900 m/s) associated with halogen based energetic composites, such as aluminum (Al) and iodine pentoxide (I2O5). Experiments show a direct correlation between apparent activation energy and flame speed suggesting that flame speed is directly influenced by chemical kinetics. Toward this end, the first principle simulations resolve key exothermic surface and intermediate chemistries contributing toward the kinetics that promote high flame speeds. Linking molecular level exothermicity to macroscopic experimental investigations provides insight into the unique role of the alumina oxide shell passivating aluminum particles. In the case of Al reacting with I2O5, the alumina shell promotes exothermic surface chemistries that reduce activation energy and increase flame speed. This finding is in contrast to Al reaction with metal oxides that show the alumina shell does not participate exothermically in the reaction.
Influence of boron doping and hydrogen passivation on recombination of photoexcited charge carriers in silicon nanocrystal/SiC multilayers
Authors: Kořínek M. , Schnabel M. , Canino M. , Kozák M. , Trojánek F. , Salava J. , Löper P. , Janz S. , Summonte C. , Malý P.
Published: August 2013

The influence of boron (B)-doping and remote plasma hydrogen passivation on the photoexcited charge carrier recombination in silicon nanocrystal/SiC multilayers was investigated in detail. The samples were prepared by high temperature annealing of amorphous (intrinsic and B-doped) Si1−xCx/SiC superlattices. The photoluminescence (PL) intensity of samples with B-doped silicon rich carbide layers was found to be up to two orders of magnitude larger and spectrally red shifted in comparison with that of the other samples. Hydrogen passivation leads to an additional increase in PL intensities. The PL decay can be described well by a mono-exponential function with a characteristic decay time of a few microseconds. This behavior agrees well with the picture of localized PL centers (surface states) together with the passivation of non-radiative defects by boron. The samples with B-doped SiC layers exhibit an additional PL band in the green spectral region that is quenched by hydrogen passivation. Its origin is attributed to defects due to suppression of crystallization of amorphous SiC layers as a result of B-doping. Measurement of ultrafast transient transmission allowed us to study the initial (picosecond) carrier dynamics. It was found to be dependent of pump intensity and interpreted in terms of multiparticle electron-hole recombination.
Solvent-based preferential deposition of functionalized carbon nanotubes on substrates
Authors: Mortuza S. M. , Banerjee Soumik
Published: August 2013

Solution-processed deposition of carbon nanotubes (CNTs) provides a cost-effective means to synthesize uniform vertically or horizontally aligned nanostructures on top of substrates. The efficacy of deposition depends on the solubility of CNTs in the solvent as well as the ordering of nanotubes relative to the substrates. These governing factors, which determine the specific morphologies of CNTs that are deposited, are determined by the molecular interactions between the CNTs and the substrate and solvent molecules. In an effort to mimic the conditions during solution-processed deposition of nanotubes on substrates, we employed molecular dynamics (MD) simulations to study systems comprising CNTs and commonly used solvents toluene and acetone sandwiched between silicon substrates. Both charged and uncharged substrates were simulated to evaluate the effect of electrostatic interactions between nanotubes and substrate on deposition. Comparison of simulated systems with pure and functionalized CNTs indicate that the presence of –COOH functional groups in CNTs is necessary for uniform deposition on substrates. Time-averaged distribution of the angles formed between the axes of the CNTs and that between the nanotubes and substrates demonstrate that functionalized carbon nanotubes (FCNTs) align parallel with the substrates to a greater extent when toluene is used as a solvent. Time-averaged density distributions obtained from our simulations illustrate that FCNTs tend to migrate towards the substrates, especially when the substrates have finite charge density. However, polar acetone molecules form layers on the substrates and thus lead to electrostatic shielding between nanotubes and substrates that hinders deposition. Hence, non-polar solvents such as toluene are more effective for deposition of nanotubes. Based on radial distribution functions (RDFs) and coordination numbers of various atoms of CNTs with respect to solvent atoms as well as with respect to that of other CNTs, we present a hypothesis that relative extent of coordination between solvent molecules and the functional groups and graphitic component of CNTs determine the solubility and the propensity of parallel alignment of FCNTs in solvents. Overall, results presented in this study provide fundamental insight to predict key factors for solution-processed deposition of well-ordered CNTs on silicon substrates.
Experimental investigation of time-resolved electron beam energy distributions generated in a transient hollow cathode discharge
Authors: Hu Jing , Rovey Joshua L.
Published: August 2013

In this paper, a retarding potential energy analyzer (RPEA) specific for pulsed electron beams within the pressure range of tens of mTorr is developed and used to investigate the energy of transient hollow cathode discharge produced electron beams. This RPEA has been applied in a pseudospark-based electron beam source at applied potential up to 20 kV. Experimental investigations under applied potential of 5 kV, 10 kV, 15 kV, and 20 kV were carried out and the time-resolved electron energy distributions are constructed. The numbers of electrons within various energy groups are calculated from the time-resolved electron energy spectra. Results show that the maximum number of electrons is emitted within the energy range of 40%–60% of the full applied potential on the pseudospark device, and varies from 22.5 ± 2.0% to 38.9±2.0% of the total number of emitted electrons. Additionally, the energy transformation efficiency of stored electrical energy to electron beam energy is calculated from presented data. The energy transformation efficiency increases from 11.4 ± 0.5% at 5 kV breakdown voltage to 23.2 ± 3.5% at 20 kV breakdown voltage.
Master equation model for Gaussian disordered organic field-effect transistors
Authors: Liu Fei , Manaka Takaaki , Iwamoto Mitsumasa
Published: August 2013

We model organic field-effect transistors with Gaussian disordered energy distribution by a coupled three-dimensional steady-sate master equation and two-dimensional Poisson equation. By numerically solving these equations, we find that under moderate gate voltages the carrier distribution in the direction perpendicular to the semiconductor/insulator is broader and there is a non-negligible part of carrier residing outside of the first layer. In addition, our computation explicitly shows that the field-effect mobility is closer to the local mobility near the interface instead of the bulk mobility.
Residual stress inspection by Eu3+ photoluminescence piezo-spectroscopy: An application in thermal barrier coatings
Authors: Zhao Yu , Ma Chunli , Huang Fengxian , Wang Chunjie , Zhao Sumei , Cui Qiliang , Cao Xueqiang , Li Fangfei
Published: August 2013

A non-destructive inspection technique was developed to measure the residual stresses in thermal barrier coatings (TBCs) by using Eu3+ photoluminescence piezo-spectroscopy. The new approach is based on the relationship between stress and the position of the main peak of 5D0→7F2 transition, which is built by the high-pressure techniques. The Eu3+ luminescent sublayer was applied in the current method to ensure that the detected position in TBCs can be well controlled. The laser used to detect Eu3+ luminescence gives a proper penetration depth and spatial resolution, which make this method suitable to detect the stresses concentrated near the interfaces between different layers. This method was successfully applied in detecting residual stress in plasma sprayed TBCs with a 8YSZ:Eu (1 mol. %) sublayer.
Universal aspects of localized excitations in graphene
Authors: Akbari-Moghanjoughi M.
Published: August 2013

Unique features of nonlinear solitary plasmon excitations in two and three dimensional massless Dirac fluids, with respect to their normal Fermi counterparts, are explored using the Bernoulli pseudopotential method. It is revealed that graphene, as a two dimensional Dirac fluid, possesses some unique characteristics with respect to the propagation of the localized plasmon excitations, which is absent in other ordinary solids. It is also shown that the Mach number limit below/above, which the localized solitary/periodic excitations propagate in a monolayer graphene has a universal value independent of the other environmental parameters such as the electron number-density and the ambient temperature. The amplitude of nonlinear solitary or periodic waves is also remarked to be independent of such parameters and depend only on the Mach-number value of the solitary or periodic excitations. These unique hydrodynamic wave features of the massless Dirac fluid are attributed to the remarkable photon-like linear energy dispersion in Dirac points of graphene material.
The size and structure of Ag particles responsible for surface plasmon effects and luminescence in Ag homogeneously doped bulk glass
Authors: Shestakov M. V. , Meledina M. , Turner S. , Tikhomirov V. K. , Verellen N. , Rodríguez V. D. , Velázquez J. J. , Van Tendeloo G. , Moshchalkov V. V.
Published: August 2013

As-prepared and heat-treated oxyfluoride glasses, co-doped with Ag nanoclusters/nanoparticles, are prepared at 0.15 at. % Ag concentration. The as-prepared glass shows an absorption band in the UV/violet attributed to the presence of amorphous Ag nanoclusters with an average size of 1.1 nm. The luminescence spectra of the untreated glass can also be ascribed to these Ag nanoclusters. Upon heat-treatment, the clusters coalesce into Ag nanoparticles with an average size of 2.3 nm, and the glasses show an extra surface plasmon absorption band in the visible. These particles, however, cease to emit due to ascribing plasmonic properties of bulk silver.
A radio-isotopic dilution technique for functional characterisation of the associations between inorganic contaminants and water-dispersible naturally occurring soil colloids
Authors: Tavakkoli Ehsan , Donner Erica , Juhasz Albert , Naidu Ravi , Lombi Enzo
Published: August 2013

Environmental context
The fate and behaviour of inorganic contaminants are dominated by soluble complex formation and interactions with naturally occurring colloids. Although the importance of these interactions has long been debated, our understanding of the mobility and bioavailability of contaminant–colloid associations has been hampered by the limitations of common operationally defined analytical techniques. The method developed in this study facilitates a step forward from operationally defined characterisation of the association between contaminants and colloids to a functional characterisation in terms of their exchangeability and potential bioavailability.

Abstract
Despite evidence that the fate and behaviour of inorganic contaminants are influenced by their interactions with water-dispersible naturally occurring soil colloids, our understanding of the mobility and bioavailability of contaminant–colloid associations has been hampered by the limitations of common operationally defined analytical techniques. In this paper, an isotopic dilution method was developed to quantify the isotopically exchangeable and non-exchangeable forms of zinc and phosphorus in filtered soil-water extracts. In addition, the effect of filter size on the determination of Zn and P exchangeability was investigated. The results showed that the isotopically non-exchangeable Zn and P in filtered soil-water extracts respectively ranged between 5 and 60% and 10 and 50% and was associated with water-dispersible colloids. Filter pore size had a significant effect on Zn and P exchangeability. Whereas the <0.1-µm filtrates contained isotopically exchangeable Zn and P fractions equal to the total Zn and P concentrations (i.e. 100% isotopically exchangeable Zn and P), the filtrates obtained from larger filter sizes (0.22, 0.45 and 0.7µm) contained increasing proportions of non-exchangeable Zn and P.
Coral reef fish association with macroalgal beds on a tropical reef system in North-eastern Brazil
Authors: Chaves L. T. C. , Pereira P. H. C. , Feitosa J. L. L.
Published: August 2013

Macroalgal beds are recognised for their role as nursery and feeding grounds for several marine species. This study was conducted in the Tamandaré reef complex within the limits of the Costa dos Corais Marine Protected Area (MPA), North-eastern Brazil. The macroalgal bed studied is subjected to several disturbances, especially from tourism. The reef fish were assessed with free dives during the day and night using visual censuses within transects (20 × 2 m) and random swims. The percentage algal cover was estimated using quadrats (40 cm2). The behavioural traits of the fish also provided an understanding of their habitat use. In total, 68 fish species were recorded. The most abundant species were representatives of the families Labridae, Pomacentridae, Acanthuridae and Haemulidae. Sargassum polyceratium, Dictyopteris delicatula and Canistrocarpus cervicornis were the most abundant macroalgae. Because the most abundant fish trophic guild included primarily mobile invertebrate feeders (41.8%) and carnivores (28.4%), it is suggested that the high-canopy macroalgae harbour epiphytic invertebrates, which these fish use for food. Thereby, the study area would act as important nursery and feeding grounds. Tourism activity (e.g. laying chairs, trampling and anchoring) may disrupt fish behaviour and life- history traits and result in damage that would require mitigation through environmental awareness and law enforcement in the most affected areas.
Glucocorticoid receptor represses proinflammatory genes at distinct steps of the transcription cycle
Authors: Gupte Rebecca , Muse Ginger W. , Chinenov Yurii , Adelman Karen , Rogatsky Inez
Published: August 2013

Widespread anti-inflammatory actions of glucocorticoid hormones are mediated by the glucocorticoid receptor (GR), a ligand-dependent transcription factor of the nuclear receptor superfamily. In conjunction with its corepressor GR-interacting protein-1 (GRIP1), GR tethers to the DNA-bound activator protein-1 and NF-κB and represses transcription of their target proinflammatory cytokine genes. However, these target genes fall into distinct classes depending on the step of the transcription cycle that is rate-limiting for their activation: Some are controlled through RNA polymerase II (PolII) recruitment and initiation, whereas others undergo signal-induced release of paused elongation complexes into productive RNA synthesis. Whether these genes are differentially regulated by GR is unknown. Here we report that, at the initiation-controlled inflammatory genes in primary macrophages, GR inhibited LPS-induced PolII occupancy. In contrast, at the elongation-controlled genes, GR did not affect PolII recruitment or transcription initiation but promoted, in a GRIP1-dependent manner, the accumulation of the pause-inducing negative elongation factor. Consistently, GR-dependent repression of elongation-controlled genes was abolished specifically in negative elongation factor-deficient macrophages. Thus, GR:GRIP1 use distinct mechanisms to repress inflammatory genes at different stages of the transcription cycle.
A class of Markov chains with no spectral gap
Authors: Kovchegov Yevgeniy , Michalowski Nicholas
Published: August 2013

In this paper we extend the results of the research started by the first author in which Karlin-McGregor diagonalization of certain reversible Markov chains over countably infinite general state spaces by orthogonal polynomials was used to estimate the rate of convergence to a stationary distribution.

We use a method of Koornwinder to generate a large and interesting family of random walks which exhibits a lack of spectral gap, and a polynomial rate of convergence to the stationary distribution. For the Chebyshev type subfamily of Markov chains, we use asymptotic techniques to obtain an upper bound of order

O

(

log
⁡

t

t

)

O\left ({\log {t} \over \sqrt {t}}\right )

and a lower bound of order

O

(

1

t

)

O\left ({1 \over \sqrt {t}}\right )

on the distance to the stationary distribution regardless of the initial state. Due to the lack of a spectral gap, these results lie outside the scope of geometric ergodicity theory.
Tunnel number one knots, 𝑚-small knots and the Morimoto conjecture
Authors: Yang Guoqiu , Yin Xunbo , Lei Fengchun
Published: August 2013

In the present paper, we show that the Morimoto Conjecture on the super additivity of the tunnel numbers of knots in

S
3

S^3

is true for knots

K
1

,

K
2

K_1,K_2

in

S
3

S^3

in which each

K
i

K_i

is either a tunnel number one or

m
m

-small,

i
=
1
,
2

i=1,2

. This extends two known results by Morimoto.
GTP gamma S stimulation of endosome fusion suggests a role for a GTP-binding protein in the priming of vesicles before fusion.
Authors: Mayorga L S , Diaz R , Colombo M I , Stahl P D
Published: August 2013

Guanosine 5'-(3-O-thio)triphosphate (GTP gamma S), a non-hydrolyzable analogue of GTP, inhibits in vitro fusion among early endocytic vesicles in the presence of high concentrations of cytosol. In this report we show that fusion is remarkably stimulated by GTP gamma S under conditions where cytosolic components are the limiting factors for the process. The amount of cytosolic factors required for maximal fusion activity is several-fold decreased by the presence of GTP gamma S. Moreover, preincubation of vesicles in the presence of cytosol and GTP gamma S allows fusion to proceed even in the absence of cytosol. Our results indicate that a GTP-binding protein facilitates the binding of cytosolic factor(s) required for endosome fusion to the endosomal membrane and stabilizes a dilution-resistant intermediate of the fusion process.
Neuronal expression of a newly identified Drosophila melanogaster G protein alpha 0 subunit.
Authors: Schmidt C J , Garen-Fazio S , Chow Y K , Neer E J
Published: August 2013

Guanine nucleotide-binding proteins (G proteins) mediate signals between activated cell-surface receptors and cellular effectors. A bovine G-protein alpha-subunit cDNA has been used to isolate similar sequences from Drosophila genomic and cDNA libraries. One class, which we call DG alpha 0, hybridized to position 47A on the second chromosome of Drosophila. The nucleotide sequence of the protein coding region of one cDNA has been determined, revealing an alpha subunit that is 81% identical with rat alpha 0. The cDNA hybridizes strongly to a 3.8 kb mRNA and weakly with a 5.3 kb message. Antibodies raised against a trp-E-DG alpha 0 fusion protein recognized a 39,000 Da protein in Drosophila extracts. In situ hybridization to adult Drosophila sections combined with immunohistochemical studies revealed expression throughout the optic lobes and central brain and in the thoracic and abdominal ganglia. DG alpha 0 message and protein were also detected in the antennae, oocytes, and ovarian nurse cells. The neuronal expression of this gene is similar to mammalian alpha 0, which is most abundantly expressed in the brain.
Regulation of slug size by the cell adhesion molecule gp80 in Dictyostelium discoideum.
Authors: Kamboj R K , Lam T Y , Siu C H
Published: August 2013

We previously provided in vitro evidence that the cell surface glycoprotein of Mr80,000 (gp80) of Dictyostelium discoideum is capable of mediating EDTA-resistant cell-cell binding. Expression of gp80 is specific for the aggregation stage when cells form tight aggregates. To investigate the physiological role of gp80, Dictyostelium cells were transformed with a vector containing gp80 cDNA fused to an actin promoter. gp80 transcripts were detected in transformed cells in their vegetative growth phase. Transformants at this stage also exhibited EDTA-resistant cell cohesion, thus providing direct in vivo evidence that gp80 mediates cell-cell binding via homophilic interaction. While aggregates of the parental strain KAX3 had the tendency to break up to form small slugs, transformants expressing an increased amount of gp80 were able to maintain the integrity of aggregates, giving rise to larger slugs, resulting in the formation of bigger fruiting bodies. To further demonstrate that the increase in slug size could be correlated with the expression of gp80, cells of the parental strain were treated with exogenous cAMP pulses to stimulate an over-expression of gp80. The treated cells also gave rise to larger slugs, consistent with the notion that slug size is influenced by intercellular adhesiveness during development.
Mitogenic signaling pathways of growth factors can be distinguished by the involvement of pertussis toxin-sensitive guanosine triphosphate-binding protein and of protein kinase C.
Authors: Nishizawa N , Okano Y , Chatani Y , Amano F , Tanaka E , Nomoto H , Nozawa Y , Kohno M
Published: August 2013

We have examined the possible involvements of pertussis toxin (PT)-sensitive guanosine triphosphate (GTP)-binding protein (Gp) and protein kinase C (PKC) in the mitogenic signaling pathways of various growth factors by the use of PT-pretreated and/or 12-O-tetradecanoyl phorbol-13-acetate (TPA)-pretreated mouse fibroblasts. Effects of PT pretreatment (inactivation of PT-sensitive Gp) and TPA pretreatment (depletion of PKC) on mitogen-induced DNA synthesis varied significantly and systematically in response to growth factors: mitogenic responses of cells to thrombin, bombesin, and bradykinin were almost completely abolished both in PT- and TPA-pretreated cells; responses to epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and vanadate were reduced to approximately 50% both in PT- and TPA-pretreated cells compared with native cells; response to basic fibroblast growth factor (bFGF) was not affected in PT-pretreated cells but was inhibited to some extent in TPA-pretreated cells. Thus, growth factors examined have been classified into three groups with regard to the involvements of PT-sensitive Gp and PKC in their signal transduction pathways. Binding of each growth factor to its receptor was not affected significantly by pretreatment of cells with PT or TPA. Inhibitory effects of PT and TPA pretreatment on each mitogen-induced DNA synthesis were not additive, suggesting that the functions of PT-sensitive Gp and PKC lie on an identical signal transduction pathway. Although all three groups of mitogens activated PKC, signaling of each growth factor depends to a varying extent on the function of PKC. Our results indicate that a single peptide growth factor such as EGF, PDGF, or bFGF acts through multiple signaling pathways to induce cell proliferation.
Developmental regulation of calmodulin-dependent adenylate cyclase activity in an insect endocrine gland.
Authors: Meller V , Sakurai S , Gilbert L I
Published: August 2013

The insect prothoracic gland produces ecdysteroids that elicit molting and metamorphosis, and neurohormone stimulation of steroidogenesis by this gland involves both Ca2+ and cyclic adenosine monophosphate second messengers. Prothoracic gland adenylate cyclase exhibits a complex Ca2+/calmodulin (CaM) dependence, a component of which requires an activated Gs alpha for expression. A developmental switch in this system has been identified that correlates with a change in both regulation and function of the gland and involves the loss of sensitivity to extracellular Ca2+ at a time approximately concurrent with the loss of Ca2+/CaM sensitivity by the adenylate cyclase. The extent of cholera toxin activation of gland Gs alpha is lowered before this developmental switch. However, no alterations in Gs alpha levels or mobility are detected, suggesting that Gs alpha interaction with another component in the signaling pathway, perhaps adenylate cyclase itself, produces the apparent Ca2+/CaM dependence and influences the ability of toxin to modify Gs alpha.
TGF-beta and retinoic acid: regulators of growth and modifiers of differentiation in human epidermal cells.
Authors: Choi Y , Fuchs E
Published: August 2013

In the epidermis of skin, a fine balance exists between proliferating progenitor cells and terminally differentiating cells. We examined the effects of TGF-beta s and retinoic acid (RA) on controlling this balance in normal and malignant human epidermal keratinocytes cultured under conditions where most morphological and biochemical features of epidermis in vivo are retained. Our results revealed marked and pleiotropic effects of both TGF-beta and RA on keratinocytes. In contrast to retinoids, TGF-beta s acted on mitotically active basal cells to retard cell proliferation. Although withdrawal from the cell cycle is a necessary prerequisite for commitment to terminal differentiation, TGF-beta s inhibited normal keratinization in suprabasal cells and promoted the type of differentiation commonly associated with wound-healing and epidermal hyperproliferation. The actions of TGF-beta s and RA on normal keratinization were synergistic, whereas those on abnormal differentiation associated with hyperproliferation were antagonistic. These observations underscore the notion that environmental changes can act separately on proliferating and differentiating cells within the population. Under the conditions used here, the action of TGF-beta s on human keratinocytes was dominant over RA, and TGF-beta s did not seem to be induced as a consequence of RA treatment. This finding is consistent with the fact that RA accelerated, rather than inhibited, proliferation in raft cultures. Collectively, our data suggest that the effects of both factors on epidermal growth and differentiation are multifaceted and the extent to which their action is coupled in keratinocytes may vary under different conditions and/or in different species.
Neoplastic transformation of mouse mammary epithelial cells by deregulated myc expression.
Authors: Telang N T , Osborne M P , Sweterlitsch L A , Narayanan R
Published: August 2013

A spontaneously immortalized, nontumorigenic mouse mammary epithelial cell line (MMEC) was transfected with an activated myc construct by electroporation. Constitutive expression of myc in MMEC resulted in anchorage independence in soft agar and tumorigenicity in nude mice. The myc-expressing MMEC showed higher saturation density, faster growth rate, and partial abrogation of serum-derived growth factor(s) requirement compared with parent MMEC. Epidermal growth factor or transforming growth factor alpha stimulated the anchorage-independent growth, but not the anchorage-dependent growth, of MMEC-myc cells. Type 1 transforming growth factor beta, on the other hand, inhibited both the anchorage-independent and anchorage-dependent growth of MMEC-myc cells. These results demonstrate that deregulated expression of myc results in neoplastic transformation iin mammary epithelial cells. Accompanying the transformation is altered sensitivity to polypeptide growth factors.
Simultaneous analysis of cell Ca2+ and Ca2(+)-stimulated chloride conductance in colonic epithelial cells (HT-29).
Authors: Morris A P , Kirk K L , Frizzell R A
Published: August 2013

We used perforated patch, whole-cell current recordings and video-based fluorescence ratio imaging to monitor the relation of plasma membrane ionic conductances to intracellular free Ca2+ within individual colonic epithelial cells (HT-29). The Ca2(+)-mediated agonist, neurotensin, activated K+ and Cl- conductances that showed different sensitivities to [Ca2+]i. The Cl- conductance was sensitive to increases or decreases in [Ca2+]i around the resting value of 76 +/- 32 (mean +/- SD) nM (n = 46), whereas activation of the K+ conductance required at least a 10-fold rise in [Ca2+]i. Neurotensin increased [Ca2+]i by stimulating a transient intracellular Ca2+ release, which was followed by a sustained rise in [Ca2+]i due to Ca2+ influx from the bath. The onset of the initial [Ca2+]i transient, monitored at a measurement window over the cell interior, lagged behind the rise in Cl- current during agonist stimulation. This lag was not present when the [Ca2+]i rise was due to Ca2+ entry from the bath, induced either by the agonist or by the Ca2+ ionophore ionomycin. The temporal differences in [Ca2+]i and Cl- current during the agonist-induced [Ca2+]i transient can be explained by a localized Ca2+ release from intracellular stores in the vicinity of the plasma membrane Cl- channel. Chloride currents recover toward basal values more rapidly than [Ca2+]i after the agonist-induced [Ca2+]i transient, and, during a sustained neurotensin-induced [Ca2+]i rise, Cl- currents inactivate. These findings suggest that an inhibitory pathway limits the increase in Cl- conductance that can be evoked by agonist. Because this Cl- current inhibition is not observed during a sustained [Ca2+]i rise induced by ionomycin, the inhibitory pathway may be mediated by another agonist-induced messenger, such as diacylglycerol.
Factors affecting dense and alpha-granule secretion from electropermeabilized human platelets: Ca(2+)-independent actions of phorbol ester and GTP gamma S.
Authors: Coorssen J R , Davidson M M , Haslam R J
Published: August 2013

Electropermeabilized human platelets containing 5-hydroxy[14C]tryptamine ([14C]5-HT) were suspended in a glutamate medium containing ATP and incubated for 10 min with (in various combinations) Ca2+ buffers, phorbol 12-myristate 13-acetate (PMA), guanine nucleotides, and thrombin. Release of [14C]5-HT and beta-thromboglobulin (beta TG) were used to measure secretion from dense and alpha-granules, respectively. Ca2+ alone induced secretion from both granule types; half-maximal effects were seen at a -log [Ca2+ free] (pCa) of 5.5 and maximal secretion at a pCa of 4.5, when approximately 80% of 5-HT and approximately 50% of beta TG were released. Addition of PMA, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), GTP, or thrombin shifted the Ca2+ dose-response curves for secretion of both 5-HT and beta TG to the left and caused small increases in the maximum secretion observed. These results suggested that secretion from alpha-granules, like that from dense granules, is a Ca(2+)-dependent process stimulated by the sequential activation of a G-protein, phospholipase C, and protein kinase C (PKC). However, high concentrations of PMA and GTP gamma S had distinct effects in the absence of Ca2+ (pCa greater than 9); 100 nM PMA released approximately 20% of platelet 5-HT but little beta TG, whereas 100 microM GTP gamma S stimulated secretion of approximately 25% of each. Simultaneous addition of PMA greatly enhanced these effects of GTP gamma S. Phosphorylation of pleckstrin in permeabilized platelets incubated with [gamma-32P]ATP was used as an index of the activation of PKC during secretion. In the absence of Ca2+, 100 nM PMA caused maximal phosphorylation of pleckstrin and 100 microM GTP gamma S was approximately 50% as effective as PMA; neither GTP gamma S nor Ca2+ enhanced the phosphorylation of pleckstrin caused by 100 nM PMA. These results indicate that, although activation of PKC promoted secretion, GTP gamma S exerted additional stimulatory effects on secretion from both dense and alpha-granules that were not mediated by PKC. Measurement of [3H]inositol phosphate formation in permeabilized platelets containing [3H]phosphoinositides showed that GTP gamma S did not stimulate phosphoinositide-specific phospholipase C in the absence of Ca2+. It follows that in permeabilized platelets, GTP gamma S can both stimulate PKC and enhance secretion via G-protein-linked effectors other than this phospholipase.