Anisotropic compression in the high pressure regime of pure and Cr-doped vanadium dioxide

We present structural studies of V$_{1-x}$Cr$_x$O$_2$ (pure, 0.7% and 2.5% Cr doped) compounds at room temperature in a diamond anvil cell for pressures up to 20 GPa using synchrotron x-ray powder diffraction. All the samples studied show a persistence of the monoclinic $M_1$ symmetry between 4 and 12 GPa. Above 12 GPa, the monoclinic $M_1$ symmetry changes to isostructural $M_x$ phase (space group $P2_1/c$) with a significant anisotropy in lattice compression of the $b$-$c$ plane of the $M_{1}$ phase. This behavior can be reconciled invoking the pressure induced charge-delocalization

Motivational factors influencing citizens to use M-Government services: a case of Kenyan ministries

Conference paper presented at 2014 eLearning Innovations Conference and Expo-KenyaInformation Communication Technologies (ICTS) have offered a wide range of opportunities to transform traditional governance in ways government services are offered. Growing research demonstrates the potential of mobile communications to radically transform service delivery by the government. M-Government is therefore emerging as the next big wave for ICT use in the public sector. This paper is based on a research done in 2012 at @iLabAfrica in Strathmore University as part of findings from a Masters dissertation. The purpose of the study was to investigate the role of m-government projects on service delivery to citizens in Kenya in order to enhance public service delivery. One of the study objectives was to evaluate motivational factors that influence citizens to use m-Government services. The study used a descriptive survey design and employed questionnaire and interview techniques to collect data. It was carried out in all the headquarters of 31 Ministries of the Government of Kenya in Nairobi County. Random sampling was used to select citizens in each Ministry. Purposive sampling was used to identify the government officials working in the ICT units. A questionnaire was designed to gather information. Data was analyzed and presented in frequency and percentage outcomes or tables. The findings reveal that most Kenyans contact the Government Ministries via Mobile phone mostly to enquire about a particular service, entitlement, or application. In terms of citizens’ awareness about m-Government services, 58.8% respondents were not aware of any m-Government services. Data on citizen interactions with m-government service reveals that the respondents on the whole had more negative experiences than positive experiences. This indicates that there is room for improvement in Kenyan service delivery. Kenyan citizens prefer services communicated or delivered via mobile phones because: relatively lower cost of mobile phone technology; access through shared usage and ownership; and mobile phones reach areas where there is no other ICT infrastructure. Recommendations included: services must be easy to use with valuable and timely content in order to ensure the service is relevant for end users; true transformation needs governments to pay close attention to re-engineering processes, reforming institutions, and creating an environment for greater accountability and transparency.Information Communication Technologies (ICTS) have offered a wide range of opportunities to transform traditional governance in ways government services are offered. Growing research demonstrates the potential of mobile communications to radically transform service delivery by the government. M-Government is therefore emerging as the next big wave for ICT use in the public sector. This paper is based on a research done in 2012 at @iLabAfrica in Strathmore University as part of findings from a Masters dissertation. The purpose of the study was to investigate the role of m-government projects on service delivery to citizens in Kenya in order to enhance public service delivery. One of the study objectives was to evaluate motivational factors that influence citizens to use m-Government services. The study used a descriptive survey design and employed questionnaire and interview techniques to collect data. It was carried out in all the headquarters of 31 Ministries of the Government of Kenya in Nairobi County. Random sampling was used to select citizens in each Ministry. Purposive sampling was used to identify the government officials working in the ICT units. A questionnaire was designed to gather information. Data was analyzed and presented in frequency and percentage outcomes or tables. The findings reveal that most Kenyans contact the Government Ministries via Mobile phone mostly to enquire about a particular service, entitlement, or application. In terms of citizens’ awareness about m-Government services, 58.8% respondents were not aware of any m-Government services. Data on citizen interactions with m-government service reveals that the respondents on the whole had more negative experiences than positive experiences. This indicates that there is room for improvement in Kenyan service delivery. Kenyan citizens prefer services communicated or delivered via mobile phones because: relatively lower cost of mobile phone technology; access through shared usage and ownership; and mobile phones reach areas where there is no other ICT infrastructure. Recommendations included: services must be easy to use with valuable and timely content in order to ensure the service is relevant for end users; true transformation needs governments to pay close attention to re-engineering processes, reforming institutions, and creating an environment for greater accountability and transparency

The effectiveness of the combination fluoxetine-naltrexone in bulimia nervosa.

Four patients with DSM-IV bulimia nervosa were treated in a crossover trial with naltrexone alone, fluoxetine alone, and a fluoxetine-naltrexone combination. Three patients presented a complete remission when treated with the fluoxetine-naltrexone combination

Development and implementation of a FT-ICR mass spectrometer for the investigation of ion conformations of peptide sequence isomers containing basic amino acid residues by gas-phase hydrogen/deuterium exchange

The gas-phase hydrogen/deuterium (H/D) exchange of protonated di- and tripeptides containing a basic amino acid residue has been studied with a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Bimolecular reactions are monitored as a function of time providing exchange efficiencies and temporal distributions for the peptide ions. Results from these experiments indicated that position of the basic residue within the peptide (i.e. N-terminal, internal, or C-terminal) influences gas-phase H/D exchange, suggesting unique peptide ion conformations. The FT-ICR mass spectrometer employed for these gas-phase H/D exchange studies was modified from its original design. Instrument modifications include development of an internal matrix assisted laser desorption ionization (MALDI) source for peptide protonation. In addition, a two-section cell was utilized, allowing control of ion motion and factors affecting gas-phase ion molecule reactions. Systems investigated in these gas-phase H/D exchange studies are peptides containing the same amino acid residues but different sequences. These sequence isomers display dissimilar reaction efficiencies and temporal distributions for deuterium incorporation depending on the primary structure of the peptide ion. Specifically, [M+H]+ peptide ions containing a N-terminal basic residue demonstrate unique H/D exchange behavior when compared to their internal and C-terminal counterparts. These differences are attributed to dissimilar intramolecular bridging interactions involved with inductive stabilization of the charge site. Gas-phase H/D exchange of peptide sequence isomers was also probed with various deuterium reagents. Findings suggest that different reagents also influence H/D exchange reaction rate efficiencies and temporal distributions. These dissimilarities are ascribed to relative gas-phase basicity and proposed mechanistic exchange differences for the deuterium reagents

Effective equilibrium states in the colored-noise model for active matter II. A unified framework for phase equilibria, structure and mechanical properties

Active particles driven by colored noise can be approximately mapped onto a system that obeys detailed balance. The effective interactions which can be derived for such a system allow the description of the structure and phase behavior of the active fluid by means of an effective free energy. In this paper we explain why the related thermodynamic results for pressure and interfacial tension do not represent the results one would measure mechanically. We derive a dynamical density functional theory, which in the steady state simultaneously validates the use of effective interactions and provides access to mechanical quantities. Our calculations suggest that in the colored-noise model the mechanical pressure in the coexisting phases might be unequal and the interfacial tension can become negative

Effective equilibrium states in mixtures of active particles driven by colored noise

We consider the steady-state behavior of pairs of active particles having different persistence times and diffusivities. To this purpose we employ the active Ornstein- Uhlenbeck model, where the particles are driven by colored noises with exponential correlation functions whose intensities and correlation times vary from species to species. By extending Fox's theory to many components, we derive by functional calculus an approximate Fokker-Planck equation for the configurational distribution function of the system. After illustrating the predicted distribution in the solvable case of two particles interacting via a harmonic potential, we consider systems of particles repelling through inverse power-law potentials. We compare the analytic predictions to computer simulations for such soft-repulsive interactions in one dimension and show that at linear order in the persistence times the theory is satisfactory. This work provides the toolbox to qualitatively describe many-body phenomena, such as demixing and depletion, by means of effective pair potentials

Pressure Induced Hydrogen Order–Disorder Transition in β-Ni(OH)2

Here we address the challenging problem of pressure induced hydrogen sublattice disordering in layered hydroxides using synchrotron X-ray powder diffraction (XRPD) and first-principles calculations..

Nanoscale Morphology of Type I Collagen is Altered in the Brtl Mouse Model of Osteogenesis Imperfecta

Bone has a complex hierarchical structure that has evolved to serve structural and metabolic roles in the body. Due to the complexity of bone structure and the number of diseases which affect the ultrastructural constituents of bone, it is important to develop quantitative methods to assess bone nanoscale properties. Autosomal dominant Osteogenesis Imperfecta results predominantly from glycine substitutions (80%) and splice site mutations (20%) in the genes encoding the α1 or α2 chains of Type I collagen. Genotype-phenotype correlations using over 830 collagen mutations have revealed that lethal mutations are located in regions crucial for collagen-ligand binding in the matrix. However, few of these correlations have been extended to collagen structure in bone. Here, an atomic force microscopy-based approach was used to image and quantitatively analyze the Dperiodic spacing of Type I collagen fibrils in femora from heterozygous (Brtl/+) mice (α1(I)G349C), compared to wild type (WT) littermates. This disease system has a well-defined change in the col1α1 allele, leading to a well characterized alteration in collagen protein structure, which are directly related to altered Type I collagen nanoscale morphology, as measured by the Dperiodic spacing. In Brtl/+ bone, the D-periodic spacing shows significantly greater variability on average and along the length of the bone compared to WT, although the average spacing was unchanged. Brtl/+ bone also had a significant difference in the population distribution of collagen D-period spacings. These changes may be due to the mutant collagen structure, or to the heterogeneity of collagen monomers in the Brtl/+ matrix. These observations at the nanoscale level provide insight into the structural basis for changes present in bone composition, geometry and mechanical integrity in Brtl/+ bones. Further studies are necessary to link these morphological observations to nanoscale mechanical integrity

Vibrational spectrum of solid picene (C_22H_14)

Recently, Mitsuhashi et al., have observed superconductivity with transition temperature up to 18 K in potassium doped picene (C22H14), a polycyclic aromatic hydrocarbon compound [Nature 464 (2010) 76]. Theoretical analysis indicate the importance of electron-phonon coupling in the superconducting mechanisms of these systems, with different emphasis on inter- and intra-molecular vibrations, depending on the approximations used. Here we present a combined experimental and ab-initio study of the Raman and infrared spectrum of undoped solid picene, which allows us to unanbiguously assign the vibrational modes. This combined study enables the identification of the modes which couple strongly to electrons and hence can play an important role in the superconducting properties of the doped samples