bluuebunny/crossref_metadata_2025 huggingface dataset:
Inter-grain interaction in random magnetic anisotropy simulation in magnetic nanocrystals
Authors: Lee S.-J. , Inami Nobuhito , Yanagihara Hideto , Kita Eiji , Mitsumata Chiharu , Ono Kanta
Published: April 2015

Effect of inter-grain exchange interaction on the coercive forces was analyzed with a numerical simulation in magnetic materials with random magnetic anisotropy. The magnetization of an assembly of magnetically interacting grains with randomly oriented uniaxial anisotropy was calculated using the Landau-Lifshitz-Gilbert equation. We supposed a single spin model where the magnetizations in a grain were aligned in the same direction, for simplicity. Calculations were carried out for an N×N×N system, where the number of grains on a side, N ranged from 16 to 128. The relation between the coercive forces HC and the grain size D is represented by HC∝Dk. With the increase of N, k decreased gradually and tended to reach a saturated value around k = 4.5–5, which dose not correspond to the primitive theory of the random anisotropy model where k = 6. The deviation was discussed in terms of the inter-grain interaction, essentially proportional to the inverse of D.
Numerical analysis of thermally assisted spin-transfer torque magnetization reversal in synthetic ferrimagnetic free layers
Authors: Shen J. , Shi M. , Tanaka T. , Matsuyama K.
Published: April 2015

The spin transfer torque magnetization reversal of synthetic ferrimagnetic free layers under pulsed temperature rise was numerically studied by solving the Landau–Lifshitz–Gilbert equation, taking into account the stochastic random fields, the temperature dependence of magnetic parameters, and the spin torque terms. The anti-parallel magnetization configuration was retained at the elevated temperature, due to interlayer dipole coupling. A significant thermal assistance effect, resulting in a 40% reduction in the switching current, was demonstrated during a nanosecond pulsed temperature rise up to 77% of the Curie temperature.
Quantum anomalous Hall effect and a nontrivial spin-texture in ultra-thin films of magnetic topological insulators
Authors: Duong Le Quy , Das Tanmoy , Feng Y. P. , Lin Hsin
Published: April 2015

We study the evolution of quantum anomalous Hall (QAH) effect for a Z2 topological insulator (TI) thin films in a proximity induced magnetic phase by a realistic layered k·p model with interlayer coupling. We examine three different magnetic configurations in which ferromagnetic (FM) layer(s) is added either from one side (FM-TI), from both sides (FM-TI-FM), or homogeneously distributed (magnetically doped) in a TI slab. We map out the thickness-dependent topological phase diagram under various experimental conditions. The critical magnetic exchange energy for the emergence of QAH effect in the latter two cases decreases monotonically with increasing number of quintuple layers (QLs), while it becomes surprisingly independent of the film thickness in the former case. The gap size of the emergent QAH insulator depends on the non-magnetic “parent” gap of the TI thin film and is tuned by the FM exchange energy, opening a versatile possibility to achieve room-temperature QAH insulator in various topological nanomaterials. Finally, we find that the emergent spin-texture in the QAH effect is very unconventional, non-“hedgehog” type; and it exhibits a chiral out-of-plane spin-flip texture within the same valence band which is reminiscent of dynamical “skyrmion” pattern, except our results are in the momentum space.
On the role of Fe ions on magnetic properties of doped TiO2 nanoparticles
Authors: Tolea F. , Grecu M. N. , Kuncser V. , Constantinescu S. Gr. , Ghica D.
Published: April 2015

The role of iron doping on magnetic properties of hydrothermal anatase TiO2:57Fe (0–1 at. %) nanoparticles is investigated by combining superconducting quantum interference device magnetometry with Mössbauer and electron paramagnetic resonance techniques. The results on both as-prepared and thermally treated samples in reduced air atmosphere reveal complexity of magnetic interactions, in connection to certain iron ion electron configurations and defects (oxygen vacancies, F-center, and Ti3+ ions). The distribution of iron ions is predominantly at nanoparticle surface layers. Formation of weak ferromagnetic domains up to 380 K is mainly related to defects, supporting the bound magnetic polaron model.
Magnetization reversal in epitaxial highly anisotropic CoFe2O4 hetero-structures
Authors: Lisfi A. , Pokharel S. , Morgan W. , Salamanca-Riba L. , Wuttig M.
Published: April 2015

Magnetization reversal in epitaxial cobalt ferrite films grown on (110) MgO substrate has been investigated through angular studies of hysteresis loop and DCD remanence curve. The angular dependences of the coercivity and the switching field of these films strongly deviate from those typically known for coherent and incoherent rotation modes. However, the best fit for these angular curves suggests that domain wall nucleation is the appropriate mode for the magnetization reversal in these hetero-structures.
Sub-ambient carbon dioxide adsorption properties of nitrogen doped graphene
Authors: Tamilarasan P. , Ramaprabhu Sundara
Published: April 2015

Carbon dioxide adsorption on carbon surface can be enhanced by doping the surface with heterogeneous atoms, which can increase local surface affinity. This study presents the carbon dioxide adsorption properties of nitrogen doped graphene at low pressures (<100 kPa). Graphene was exposed to nitrogen plasma, which dopes nitrogen atoms into carbon hexagonal lattice, mainly in pyridinic and pyrrolic forms. It is found that nitrogen doping significantly improves the CO2 adsorption capacity at all temperatures, due to the enrichment of local Lewis basic sites. In general, isotherm and thermodynamic parameters suggest that doped nitrogen sites have nearly same adsorption energy of surface defects and residual functional groups. The isosteric heat of adsorption remains in physisorption range, which falls with surface coverage, suggesting the distribution of magnitude of adsorption energy. The absolute values of isosteric heat and entropy of adsorption are slightly increased upon nitrogen doping.
Tunable zinc interstitial related defects in ZnMgO and ZnCdO films
Authors: Li Wanjun , Fang Liang , Qin Guoping , Ruan Haibo , Zhang Hong , Kong Chunyang , Ye Lijuan , Zhang Ping , Wu Fang
Published: April 2015

We report tunable band gap of ZnO thin films grown on quartz substrates by radio frequency magnetron sputtering. The zinc interstitial (Zni) defects in ZnO films were investigated by X-ray diffraction, Raman scattering, Auger spectra, first-principle calculations, and Hall measurement. Undoped ZnO film exhibits an anomalous Raman mode at 275 cm−1. We first report that 275 cm−1 mode also can be observed in ZnO films alloyed with Mg and Cd, whose Raman intensities, interestingly, decrease and increase with increasing Mg and Cd alloying content, respectively. Combined with the previous investigations, it is deduced that 275 cm−1 mode is attributed to Zni related defects, which is demonstrated by our further experiment and theoretical calculation. Consequently, the concentration of Zni related defects in ZnO can be tuned by alloying Mg and Cd impurity, which gives rise to different conductivity in ZnO films. These investigations help to further understand the controversial origin of the additional Raman mode at 275 cm−1 and also the natural n-type conductivity in ZnO.
Magnetic and magnetodielectric properties of Y3−xLaxFe5O12 ceramics
Authors: Wu Huarui , Huang Fengzhen , Xu Tingting , Ti Ruixia , Lu Xiaomei , Kan Yi , Lv Xueliang , Zhu Weili , Zhu Jinsong
Published: April 2015

Y3−xLaxFe5O12 (x = 0–0.5) ceramics with garnet structure are prepared by the solid state reaction method and their structural, magnetic, and magnetodielectric properties are investigated systematically. La3+ substitution leads to lattice expansion and possible ion transposition, which oppositely affect the variation of Fe2+ concentration. As a result, both the saturation magnetization and the intrinsic magnetodielectric effect first increase and then decrease with the increase of La concentration. More interestingly, room temperature large magnetodielectric coefficient of about −5% is obtained at 106 Hz and 0.9 T for Y2.7La0.3Fe5O12 ceramics. This study provides a feasible alternative method for modulating the saturation magnetization and the magnetodielectric effect of Y3Fe5O12-based materials.
First experiments probing the collision of parallel magnetic fields using laser-produced plasmas
Authors: Rosenberg M. J. , Li C. K. , Fox W. , Igumenshchev I. , Séguin F. H. , Town R. P. J. , Frenje J. A. , Stoeckl C. , Glebov V. , Petrasso R. D.
Published: April 2015

Novel experiments to study the strongly-driven collision of parallel magnetic fields in β ∼ 10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.
Eddy current interactions in a ferromagnet-normal metal bilayer structure, and its impact on ferromagnetic resonance lineshapes
Authors: Flovik Vegard , Macià Ferran , Kent Andrew D. , Wahlström Erik
Published: April 2015

We investigate the effect of eddy currents on ferromagnetic resonance (FMR) in ferromagnet-normal metal (FM/NM) bilayer structures. Eddy-current effects are usually neglected for NM layer thicknesses below the microwave (MW) skin depth (≃800 nm for Au at 10 GHz). However, we show that in much thinner NM layers (10–100 nm of Au or Cu) they induce a phase shift in the FMR excitation when the MW driving field has a component perpendicular to the sample plane. This results in a strong asymmetry of the measured absorption lines. In contrast to typical eddy-current effects, the asymmetry is larger for thinner NM layers and is tunable through changing the sample geometry and the NM layer thickness.
Influence of surface temperature and wettability on droplet evaporation
Authors: Hsu Chin-Chi , Su Tsung-Wen , Wu Chun-Hui , Kuo Long-Sheng , Chen Ping-Hei
Published: April 2015

The evaporation characteristics of sessile water droplets on various wettability substrates (hydrophilic, hydrophobic, and mixed wettability surfaces) were experimentally investigated in this study. Placing droplets on a regulated superheated surface led to rapid vapor bubble formation. The droplet parameters, such as the contact angle and volume evolution over evaporation time, were experimentally measured. The results revealed that surface wettability plays a critical role not only in vapor bubble dynamics but also in evaporation.
Estimating interfacial thermal conductivity in metamaterials through heat flux mapping
Authors: Canbazoglu Fatih M. , Vemuri Krishna P. , Bandaru Prabhakar R.
Published: April 2015

The variability of the thickness as well as the thermal conductivity of interfaces in composites may significantly influence thermal transport characteristics and the notion of a metamaterial as an effective medium. The consequent modulations of the heat flux passage are analytically and experimentally examined through a non-contact methodology using radiative imaging, on a model anisotropic thermal metamaterial. It was indicated that a lower Al layer/silver interfacial epoxy ratio of ∼25 compared to that of a Al layer/alumina interfacial epoxy (of ∼39) contributes to a smaller deviation of the heat flux bending angle.
Similarity solution for flow over an unsteady nonlinearly stretching rotating disk
Authors: Hobiny Aatef , Ahmad Bashir , Alsaedi Ahmed , Jalil Mudassar , Asghar Saleem
Published: April 2015

The unsteady laminar flow of an incompressible viscous fluid over a nonlinearly stretching rotating disk is investigated. The axisymmetric three-dimensional boundary layer equations are reduced into self-similar form with the help of new similarity transformation. The resulting coupled nonlinear equations are solved numerically using shooting method coupled with Range-Kutta 6 (RK-6). An exact analytical solution for the large stretching parameter is also presented. Some interesting observations are made while interpreting the results physically. Dual solutions are obtained due to the presence of unsteadiness parameter for the nonlinear stretching of the rotating disk. The analytical results reveal that for large stretching parameter the azimuthal velocity becomes negligible and the flow behaviors turn into steady state, which is the most surprising observation of the paper. These results are also verified numerically by solving original self similar equations using shooting method.
Polarization-dependent optical excitation of gap plasmon polaritons through rectangular hole arrays
Authors: Jakovljević Milka M. , Isić Goran , Dastmalchi Babak , Bergmair Iris , Hingerl Kurt , Gajić Radoš
Published: April 2015

We use variable-angle reflection ellipsometry to investigate the polarization-dependent optical excitation of highly confined gap plasmon polaritons in a fishnet metamaterial with rectangular holes. From the amplitude of features in the ellipsometric spectra and their variation with the angle of incidence, we find that the gap plasmon polaritons supported by the 35 nm thick silica gap layer are much more efficiently excited by light polarized along the short axis of holes. This inference is corroborated by numerical simulations of plasmonic near fields, while the simulated ellipsometric spectra are in excellent agreement with the measurements. By examining fishnet structures with decreasing hole sizes but a fixed aspect ratio, we find that the polarization dependence persists even in the absence of hole resonances suggesting that it can be explained by the quasi-static polarizability of holes.
Elemental composition of plants from the serpentine soil of Sugashima Island, Japan
Authors: Mizuno Takafumi , Kirihata Yoko
Published: April 2015

Sugashima Island has the largest community of Buxus microphylla in Japan and a unique flora of several serpentine-associated plants. We determined the concentrations of metals (iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), chromium (Cr) and strontium (Sr)) and macro elements (potassium (K), calcium (Ca) and magnesium (Mg)) in 75 plants inhabiting this area and considered the key to their adaptation to the high-metal environment. The soil showed typical serpentine characteristics of high Ni, Cr, Co and low Ca : Mg quotient, and the soil pH(H2O) ranged from 6.2 to 8.6. Buxus microphylla had the highest Ni concentration (400 mg kg–1) among the plants collected, and Viola grypoceras and Swertia japonica accumulated over 100 mg kg–1 Ni. Swertia japonica accumulated the highest concentrations of Fe, Cr and Co, and Dendropanax trifidus accumulated the highest concentrations of Mn and Zn. The concentrations of Ni and Fe in the plants, particularly in some alkalophilic plants that are found in areas with calcareous soil in Japan, were significantly correlated. Our results suggested that active Fe uptake could be one of the key characteristics for plant adaptation to and survival on the serpentine soils of Sugashima Island, although the dominance of B. microphylla may be associated with its strong Ni tolerance without accumulating high concentrations of Fe.
High-spin Mn–oxo complexes and their relevance to the oxygen-evolving complex within photosystem II
Authors: Gupta Rupal , Taguchi Taketo , Lassalle-Kaiser Benedikt , Bominaar Emile L. , Yano Junko , Hendrich Michael P. , Borovik A. S.
Published: April 2015

Significance

Metal complexes with terminal oxido ligands are important in a wide variety of transformations, including a high valent manganese-oxido unit that is involved in the O–O bond-forming step in photosynthetic water oxidation. Theoretical proposals suggest that a Mn
IV
–oxyl radical species is present, yet such species have not been observed experimentally. Using a combination of experimental measurements and theoretical calculations, we show here that the bonding within the Mn–oxido unit is best described as highly covalent, with 0.45 spins on the oxido ligand. These findings offer a counter explanation for the putative high valent manganese species in photosynthesis as an energetically accessible, high-spin Mn
V
–oxido unit instead of a Mn
IV
–oxyl radical species.
Migratory Characteristics and Passage of Paddlefishat Two Southeastern U.S. Lock‐and‐Dam Systems
Authors: Simcox Brandon L. , DeVries Dennis R. , Wright Russell A.
Published: April 2015

Dams have many effects on river systems, including impeding the migratory movements of fishes. However, locks associated with lock‐and‐dam structures may be useful for passing fish during their migrations. We investigated the potential to facilitate fish passage at dams through two navigational lock structures on the Alabama River, Alabama—Millers Ferry Lock and Dam (L&D) and Claiborne L&D—using targeted, nonnavigational lock operations. The movements of Paddlefish Polyodon spathula with implanted ultrasonic tags and/or radio tags were tracked via both manual receivers and submersible ultrasonic receivers (SURs) deployed inside of the lock chambers and above and below each dam to quantify migration characteristics and determine whether fish passage occurred. We tagged a total of 96 fish (79 received sonic tags, 4 received radio tags, and 13 received both types of tag), and we recorded over 275,000 SUR detections of 84 individuals and 91 manual detections of 39 individuals. Although nonnavigational lock operations increased the number of days available for potential passage by 0.5–4.7 times, only seven Paddlefish passed upstream through the locks (8% passage rate). Most of the fish movement past dams occurred during spring, when many riverine fish make spawning migrations. Movement past Claiborne Dam occurred most often over the spillway (87% of passage) during high‐water events. Our results suggest that while specialized nonnavigational lock operations along the Alabama River increased opportunities for upstream fish passage, relatively few Paddlefish actually moved upstream through the lock chambers.
Pulmonary Hypertension in Obstructive Sleep Apnea: Is it Clinically Significant? a Critical Analysis of the Association and Pathophysiology
Authors: Kholdani Cyrus , Fares Wassim H. , Mohsenin Vahid
Published: April 2015

The development of pulmonary hypertension is a poor prognostic sign in patients with obstructive sleep apnea (OSA) and affects both mortality and quality of life. Although pulmonary hypertension in OSA is traditionally viewed as a result of apneas and intermittent hypoxia during sleep, recent studies indicate that neither of these factors correlates very well with pulmonary artery pressure. Human data show that pulmonary hypertension in the setting of OSA is, in large part, due to left heart dysfunction with either preserved or diminished ejection fraction. Longstanding increased left heart filling pressures eventually lead to pulmonary venous hypertension. The combination of hypoxic pulmonary vasoconstriction and pulmonary venous hypertension with abnormal production of mediators will result in vascular cell proliferation and aberrant vascular remodeling leading to pulmonary hypertension. These changes are in many ways similar to those seen in other forms of pulmonary hypertension and suggest shared mechanisms. The majority of patients with OSA do not receive a diagnosis and are undertreated. Appreciating the high prevalence and understanding the mechanisms of pulmonary hypertension in OSA would lead to better recognition and management of the condition.
Zeros of the dilogarithm
Authors: O’Sullivan Cormac
Published: April 2015

We show that the dilogarithm has at most one zero on each branch, that each zero is close to a root of unity, and that they may be found to any precision with Newton’s method. This work is motivated by applications to the asymptotics of coefficients in partial fraction decompositions considered by Rademacher. We also survey what is known about zeros of polylogarithms in general.
Twitchin kinase interacts with MAPKAP kinase 2 inCaenorhabditis elegansstriated muscle
Authors: Matsunaga Yohei , Qadota Hiroshi , Furukawa Miho , Choe Heejoo (Helen) , Benian Guy M.
Published: April 2015

In Caenorhabditis elegans, twitchin is a giant polypeptide located in muscle A-bands. The protein kinase of twitchin is autoinhibited by 45 residues upstream (NL) and 60 residues downstream (CRD) of the kinase catalytic core. Molecular dynamics simulation on a twitchin fragment revealed that the NL is released by pulling force. However, it is unclear how the CRD is removed. To identify proteins that may remove the CRD, we performed a yeast two-hybrid screen using twitchin kinase as bait. One interactor is MAK-1, C. elegans orthologue of MAPKAP kinase 2. MAPKAP kinase 2 is phosphorylated and activated by p38 MAP kinase. We demonstrate that the CRD of twitchin is important for binding to MAK-1. mak-1 is expressed in nematode body wall muscle, and antibodies to MAK-1 localize between and around Z-disk analogues and to the edge of A-bands. Whereas unc-22 mutants are completely resistant, mak-1 mutants are partially resistant to nicotine. MAK-1 can phosphorylate twitchin NL-Kin-CRD in vitro. Genetic data suggest the involvement of two other mak-1 paralogues and two orthologues of p38 MAP kinase. These results suggest that MAK-1 is an activator of twitchin kinase and that the p38 MAP kinase pathway may be involved in the regulation of twitchin.
The RhoGEF DOCK10 is essential for dendritic spine morphogenesis
Authors: Jaudon Fanny , Raynaud Fabrice , Wehrlé Rosine , Bellanger Jean-Michel , Doulazmi Mohamed , Vodjdani Guilan , Gasman Stéphane , Fagni Laurent , Dusart Isabelle , Debant Anne , Schmidt Susanne
Published: April 2015

By regulating actin cytoskeleton dynamics, Rho GTPases and their activators RhoGEFs are implicated in various aspects of neuronal differentiation, including dendritogenesis and synaptogenesis. Purkinje cells (PCs) of the cerebellum, by developing spectacular dendrites covered with spines, represent an attractive model system in which to decipher the molecular signaling underlying these processes. To identify novel regulators of dendritic spine morphogenesis among members of the poorly characterized DOCK family of RhoGEFs, we performed gene expression profiling of fluorescence-activated cell sorting (FACS)-purified murine PCs at various stages of their postnatal differentiation. We found a strong increase in the expression of the Cdc42-specific GEF DOCK10. Depleting DOCK10 in organotypic cerebellar cultures resulted in dramatic dendritic spine defects in PCs. Accordingly, in mouse hippocampal neurons, depletion of DOCK10 or expression of a DOCK10 GEF-dead mutant led to a strong decrease in spine density and size. Conversely, overexpression of DOCK10 led to increased spine formation. We show that DOCK10 function in spinogenesis is mediated mainly by Cdc42 and its downstream effectors N-WASP and PAK3, although DOCK10 is also able to activate Rac1. Our global approach thus identifies an unprecedented function for DOCK10 as a novel regulator of dendritic spine morphogenesis via a Cdc42-mediated pathway.
Casein kinase 1 controls the activation threshold of an α-arrestin by multisite phosphorylation of the interdomain hinge
Authors: Herrador Antonio , Livas Daniela , Soletto Lucía , Becuwe Michel , Léon Sébastien , Vincent Olivier
Published: April 2015

α-Arrestins play a key role as trafficking adaptors in both yeast and mammals. The yeast Rim8/Art9 α-arrestin mediates the recruitment of endosomal sorting complex required for transport (ESCRT) to the seven-transmembrane protein Rim21 in the ambient pH signaling RIM pathway. ESCRT is believed to function as a signaling platform that enables the proteolytic activation of the Rim101 transcription factor upon external alkalization. Here we provide evidence that the pH signal promotes the stable association of Rim8 with Rim21 at the plasma membrane. We show that Rim8 is phosphorylated in a pH-independent but Rim21-dependent manner by the plasma membrane–associated casein kinase 1 (CK1). We further show that this process involves a cascade of phosphorylation events within the hinge region connecting the arrestin domains. Strikingly, loss of casein kinase 1 activity causes constitutive activation of the RIM pathway, and, accordingly, pH signaling is activated in a phosphodeficient Rim8 mutant and impaired in the corresponding phosphomimetic mutant. Our results indicate that Rim8 phosphorylation prevents its accumulation at the plasma membrane at acidic pH and thereby inhibits RIM signaling. These findings support a model in which CK1-mediated phosphorylation of Rim8 contributes to setting a signaling threshold required to inhibit the RIM pathway at acidic pH.
Cyclin-dependent kinase 5 acts as a critical determinant of AKT-dependent proliferation and regulates differential gene expression by the androgen receptor in prostate cancer cells
Authors: Lindqvist Julia , Imanishi Susumu Y. , Torvaldson Elin , Malinen Marjo , Remes Mika , Örn Fanny , Palvimo Jorma J. , Eriksson John E.
Published: April 2015

Contrary to cell cycle–associated cyclin-dependent kinases, CDK5 is best known for its regulation of signaling processes in differentiated cells and its destructive activation in Alzheimer's disease. Recently, CDK5 has been implicated in a number of different cancers, but how it is able to stimulate cancer-related signaling pathways remains enigmatic. Our goal was to study the cancer-promoting mechanisms of CDK5 in prostate cancer. We observed that CDK5 is necessary for proliferation of several prostate cancer cell lines. Correspondingly, there was considerable growth promotion when CDK5 was overexpressed. When examining the reasons for the altered proliferation effects, we observed that CDK5 phosphorylates S308 on the androgen receptor (AR), resulting in its stabilization and differential expression of AR target genes including several growth-priming transcription factors. However, the amplified cell growth was found to be separated from AR signaling, further corroborated by CDK5-depdent proliferation of AR null cells. Instead, we found that the key growth-promoting effect was due to specific CDK5-mediated AKT activation. Down-regulation of CDK5 repressed AKT phosphorylation by altering its intracellular localization, immediately followed by prominent cell cycle inhibition. Taken together, these results suggest that CDK5 acts as a crucial signaling hub in prostate cancer cells by controlling androgen responses through AR, maintaining and accelerating cell proliferation through AKT activation, and releasing cell cycle breaks.
Reductions in virological failure and drug resistance in Chinese antiretroviral-treated patients due to lamivudine-based regimens, 2003–12
Authors: Xing Hui , Ruan Yuhua , Hsi Jenny H. , Kan Wei , Liao Lingjie , Leng Xuebing , Wang Jing , He Cui , Shao Yiming ,   on behalf of the National HIVDR Working Group
Published: April 2015

Background

China's National Free Antiretroviral Treatment Program (NFATP) has significantly scaled up and standardized treatment since 2008. Meanwhile, no study worldwide has examined on a large scale the effects of rapid ART programme scale-up on treatment outcomes in resource-limited settings.

Methods

We used China's national HIV drug resistance (HIVDR) surveillance database to determine virological failure, acquired drug resistance and poor adherence rates after 12–15 months of first-line ART. A total of 2252 patients were examined, with 1431 patients having initiated ART before 2008 and 821 since 2008.

Findings

Since 2008, virological failure at 12–15 months of treatment improved from 26.6% to 12.1%, and HIVDR rates also significantly decreased from 15.4% to 5.4%. However, these successes are strongly associated with the standardized use of lamivudine-based regimens in place of didanosine-based regimens. Patients who initiated lamivudine-based regimens before 2008 showed significant improvement in adherence [missed doses adjusted OR (AOR), 0.65; 95% CI, 0.45–0.96], virological failure (AOR, 0.29; 95% CI, 0.22–0.39) and HIVDR outcomes (AOR, 0.29; 95% CI, 0.20–0.42) compared with those who initiated didanosine-based regimens. Meanwhile, among only patients on lamivudine-based regimens, no significant changes were observed between those who initiated before 2008 and those who initiated since 2008.

Conclusions

China's NFATP has been largely successful throughout the scale-up, with an overall reduction in virological failure and HIVDR. However, excluding the effect of lamivudine-based regimens, it remains crucial for the programme to improve patient adherence and quality of care, particularly in key vulnerable populations such as those infected through injecting drug or blood routes.
Risk Factors of Refracture and Morbidity During Removal of Titanium Pediatric Proximal Femoral Locking Plates in Children With Cerebral Palsy
Authors: Inan Muharrem , Sarikaya Ilker A. , Seker Ali , Guven Mehmet F.
Published: April 2015

Background:

Pediatric proximal femoral locking plates (PFLPs) are widely used when performing proximal femoral osteotomy in children with cerebral palsy (CP). The purpose of this study is to report the difficulties and risk factors of titanium PFLPs removal in CP.

Methods:

PFLP removal was performed in 58 hips of 33 patients (17 males, 16 females). The mean age at the time of surgery (plate removal) was 10.9 (range, 5.7 to 19.2) years. The patients were divided into 2 groups as group 1 and 2, if any difficulty was observed during surgery or not.

Results:

Difficulty was not detected in 42 (72.4%) hips (group 1). Difficulties were encountered in 16 (27.6%) hips (group 2). A total of 364 screws were used (259 in group 1, 105 in group 2). The mean plate screw density ratios were 0.88 in group 1 and 0.94 in group 2. The difference between group 1 and 2 was statistically significant. The mean duration between the insertion and removal of the PFLP was 14.9 months (11.9 mo in group 1, 22.7 mo in group 2). The difference between group 1 and 2 was statistically significant. The screw heads were cut and the shafts were left in the bone in 4 hips (4 screws); 3 of these 4 screws were calcar screws. Therefore, calcar screw application can be accepted as a handicap for screw removal.

Conclusions:

As a conclusion, this study suggested that difficulty in titanium PFLP removal in CP is common and PFLP removal is not a harmless procedure. A longer time from internal fixation to removal, increased plate screw density ratio, and calcar screw application are risk factors for difficulties in titanium PFLP removal in CP.

Level of Evidence:

Level III.
First 50 Pediatric and Adolescent Elbow Arthroscopies: Analysis of Indications and Complications
Authors: Vavken Patrick , Müller Andreas M. , Camathias Carlo
Published: April 2015

Background:

Elbow arthroscopy is a challenging, yet extremely productive procedure in orthopaedic sports medicine. The severely confined anatomy of the pediatric and adolescent elbow is particularly prone for perioperative complications. This study focuses on the indications and complications of the first 50 elbow arthroscopies in skeletally immature patients done in a specialized pediatric orthopaedic department.

Purpose:

To review analysis of indications and complications in pediatric and adolescent elbow arthroscopy. We hypothesized that the complication rate in these patients is similar to adults.

Methods:

Data on 50 consecutive elbow arthroscopies were prospectively gathered in a dedicated database and retrospectively analyzed for indications and perioperative complications. All procedures were performed by a surgeon trained in orthopaedic sports medicine.

Results:

A total of 26 boys and 24 girls with a mean age of 13.6±3.3 years at the time of surgery and a minimum follow-up of 1 year were included.

Fifty-eight percent were treated for osteochondritis dissecans, 24% for arthrofibrosis, 14% for a congenital disorder, and 4% for a posttraumatic problem other than arthrofibrosis. The complication rate was 8%, including 3 cases of transient neuropraxia and 1 superficial wound infection. There were no major complications such as septic arthritis, vascular injury, or permanent nerve damage. All complications resolved fully with conservative treatment, no revision were required.

Discussion:

Although osteochondritis dissecans is still the leading reason for such surgery, fractures and posttraumatic conditions are becoming more important. With a rate of 5% to 8% of minor, fully resolving complications such an increase is not a reason for concerns.

Level of Evidence:

Level IV—case series.
Characterization of Hip Morphology in Children With Mucopolysaccharidosis Types I and II
Authors: Ashby Elizabeth , Baker Markus , Eastwood Deborah M.
Published: April 2015

Background:

The purpose of this study is to describe the natural history of hip morphology in patients with mucopolysaccharidoses (MPS) I and MPS II.

Methodology:

This is a retrospective radiographic analysis of 88 hips in 44 children with MPS I and II. Radiographs were examined to determine hip migration, femoral head sphericity, and acetabular dysplasia at different ages throughout childhood. In individual hips, change in morphology and rate of change were analyzed.

Results:

There was a high rate of hip migration and femoral head dysplasia in both MPS I and MPS II. Progressive migration was seen in three quarters of hips and progressive femoral head deformity in over half of hips. Acetabular dysplasia was variable, ranging from normal to severely dysplastic, but did not change with time. Overall, hips were more dysplastic in MPS I than MPS II.

Conclusions:

Hip morphology is variable in MPS I and MPS II ranging from almost normal to severely dysplastic. Some hips do not deteriorate with time and thus surgical intervention may not be necessary in all cases. Deterioration is slow allowing time to plan a holistic approach to treatment.

Level of Evidence:

Level IV—case series.
Outcomes of Orthopaedic Surgery With and Without an External Femoral Derotational Osteotomy in Children With Cerebral Palsy
Authors: McMulkin Mark L. , Gordon Andi B. , Caskey Paul M. , Tompkins Bryan J. , Baird Glen O.
Published: April 2015

Background:

Ambulatory children with cerebral palsy (CP) often present with multiple deviations in all planes including increased internal hip rotation during gait. Excessive femoral anteversion is a common cause of deviation managed surgically with an external femoral derotational osteotomy (FDO). The purpose of this study was to evaluate the gait and functional outcomes of a group of subjects with CP who underwent surgical intervention that included an FDO compared with a match group with indications of internal hip rotation that did not receive an FDO.

Methods:

For this retrospective study, subjects were identified from the Motion Analysis Laboratory database that had orthopaedic surgery including an FDO (FDO group). A control group was established from a chart review identifying subjects that had indications for an FDO, but did not have this surgery (No-FDO group). All subjects had preoperative and postoperative gait studies. Subjects categorized as Gross Motor Function Classification System (GMFCS) levels I and II in both FDO and No-FDO groups were combined for analysis. Subjects rated as GMFCS level III were analyzed separately. Preoperative to postoperative kinematic and kinetic variables, Gait Deviation Index, net oxygen cost, and PODCI scores were analyzed with paired t tests.

Results:

Typical sagittal plane kinematic variables improved significantly by equivalent magnitudes for both FDO and No-FDO groups (GMFCS I/II and III). Transverse plane improvements were only seen for the FDO group (GMFCS I/II and III). The Gait Deviation Index, an overall index of kinematics, improved by a significantly greater amount for the FDO group across GMFCS levels I/II and III. Net oxygen cost improved for both FDO and No-FDO for GMFCS I/II. PODCI scores improved for FDO and No-FDO in GMFCS I/II, but only the FDO group for GMFCS III.

Conclusions:

For children with CP, inclusion of an FDO in the surgical intervention, when indicated, resulted in improved outcomes. Overall gait kinematic improvements were significantly greater when an FDO was included in the surgical management.

Level of Evidence:

Level III—retrospective comparative study.
Status Epilepticus Due to Cat Scratch Disease
Authors: Schuster Angel Lorrine , Honeycutt Travis C.B. , Hamrick Harvey James
Published: April 2015

Despite the publication of a number of case reports since the 1950s, physician awareness of the unique relationship between cat scratch disease (CSD) and acute encephalopathy remains limited. This report alerts emergency medicine physicians to include CSD encephalopathy (CSDE) in the differential diagnosis when a previously healthy child presents with status epilepticus. Prompt recognition of this relationship impacts the selection of initial diagnostic studies and antibiotic choices and permits reliable insight into prognosis. The 2 cases are from different eras and demonstrate the significant diagnostic advances in the past 3 decades forBartonella henselaeinfection. Both children were treated with antibiotics, and both had resolution of all neurological symptoms. However, the role of antibiotics in the treatment and outcome of CSDE remains speculative. Lastly, the report suggests potential areas of investigation to address immune-mediated mechanisms in the pathogenesis of CSDE.
How to calculate the non-synonymous to synonymous rate ratio of protein-coding genes under the Fisher–Wright mutation–selection framework
Authors: dos Reis Mario
Published: April 2015

First principles of population genetics are used to obtain formulae relating the non-synonymous to synonymous substitution rate ratio to the selection coefficients acting at codon sites in protein-coding genes. Two theoretical cases are discussed and two examples from real data (a chloroplast gene and a virus polymerase) are given. The formulae give much insight into the dynamics of non-synonymous substitutions and may inform the development of methods to detect adaptive evolution.
XAS and XMCD studies of magnetic properties modifications of Pt/Co/Au and Pt/Co/Pt trilayers induced by Ga+ions irradiation
Authors: Mazalski Piotr , Sveklo Iosif , Kurant Zbigniew , Ollefs Katharina , Rogalev Andrei , Wilhelm Fabrice , Fassbender Juergen , Baczewski Lech Tomasz , Wawro Andrzej , Maziewski Andrzej
Published: April 2015

Magnetic and magneto-optical properties of Pt/Co/Au and Pt/Co/Pt trilayers subjected to 30 keV Ga+ion irradiation are compared. In two-dimensional maps of these properties as a function of cobalt thickness and ion fluence, two branches with perpendicular magnetic anisotropy (PMA) for Pt/Co/Pt trilayers are well distinguished. The replacement of the Pt capping layer with Au results in the two branches still being visible but the in-plane anisotropy for the low-fluence branch is suppressed whereas the high-fluence branch displays PMA. The X-ray absorption spectra and X-ray magnetic circular dichroism (XMCD) spectra are discussed and compared with non-irradiated reference samples. The changes of their shapes and peak amplitude, particularly for the high-fluence branch, are related to the modifications of the local environment of Co(Pt) atoms and the etching effects induced by ion irradiation. Additionally, in irradiated trilayers the XMCD measurements at the PtL2,3-edge reveal an increase of the magnetic moment induced in Pt atoms.
A novel two-dimensional cadmium(II) complex: poly[diaquatris(μ4-cyclohexane-1,4-dicarboxylato)bis[2-(pyridin-4-yl)-1H-benzimidazole]tricadmium(II)
Authors: Yang Xiu-Hong , Yang Ming-Xing , Chen Li-Juan , Guo Jing , Lin Shen
Published: April 2015

The title compound, [Cd3(C8H10O4)3(C12H9N3)2(H2O)2]nor [Cd3(chdc)3(4-PyBIm)2(H2O)2]n, was synthesized hydrothermally from the reaction of Cd(CH3COO)2·2H2O with 2-(pyridin-4-yl)-1H-benzimidazole (4-PyBIm) and cyclohexane-1,4-dicarboxylic acid (1,4-chdcH2). The asymmetric unit consists of one and a half CdIIcations, one 4-PyBIm ligand, one and a half 1,4-chdc2−ligands and one coordinated water molecule. The central CdIIcation, located on an inversion centre, is coordinated by six carboxylate O atoms from six 1,4-chdc2−ligands to complete an elongated octahedral coordination geometry. The two terminal rotationally symmetric CdIIcations each exhibits a distorted pentagonal–bipyramidal geometry, coordinated by one N atom from 4-PyBIm, five O atoms from three 1,4-chdc2−ligands and one O atom from an aqua ligand. The 1,4-chdc2−ligands possess two conformations,i.e.e,e-trans-chdc2−ande,a-cis-chdc2−. Thecis-1,4-chdc2−ligands bridge the CdIIcations to form a trinuclear {Cd3}-based chain along thebaxis, while thetrans-1,4-chdc2−ligands further link adjacent one-dimensional chains to construct an interesting two-dimensional network.
Crystal structure of poly[di-μ-aqua-{5-[(1Z)-2-(4-chlorophenyl)-1-cyanoethenyl]-1,2,3,4-tetrazol-1-ido-κN1}sodium]
Authors: Mague Joel T. , Mohamed Shaaban K. , Akkurt Mehmet , El-Saghier Ahmed M. M. , Albayati Mustafa R.
Published: April 2015

In the title compound, [Na(C10H5ClN5)(H2O)2]n, infinite chains of [Na(H2O)2]+cations having a diamond-shaped cross-section and running parallel to thebaxis are formed. O—H...N hydrogen bonds to the anions generate layers parallel to (100) which have the chlorobenzenecyanoethenyl substituents protruding from both surfaces. The sodium ion makes a short contact of 2.4801 (13) Å with the N atom of the tetrazolide ring which issynto the cyano N atom.
Crystal structure of 11-(2,3-dimethoxyphenyl)-14-methyl-12-oxa-8,14-diazatetracyclo[8.3.3.01,10.02,7]hexadeca-2(7),3,5-triene-9,13-dione
Authors: Savithri M. P. , Suresh M. , Raghunathan R. , Raja R. , SubbiahPandi A.
Published: April 2015

The title compound, C22H22N2O5, contains two conformationally similar molecules (AandB) in its the asymmetric unit (r.m.s. overlay fit for the 29 non-H atoms = 0.194 Å). In each molecule, the lactone ring has an envelope conformation with the spiro C atom as the flap. In the crystal,A+AandB+Binversion dimers linked by pairs of N—H...O hydrgen bonds occur; in both cases,R22(8) loops are generated. A weak C—H...O interaction is also observed, which links the dimers into [010] chains.
Crystal stucture of methyl 2-({[2-(methoxycarbonyl)phenyl]carbamoyl}amino)benzoate
Authors: Yassine Hasna , Khouili Mostafa , El Ammari Lahcen , Saadi Mohamed , Ketatni El Mostafa
Published: April 2015

In the title compound, C17H16N2O5, the dihedral angles between the central urea [N—C(=O)—N] fragment and its attached benzene rings are 20.20 (14) and 24.24 (13)°; the dihedral angle between the aromatic rings is 42.1 (1)°. The molecular conformation is consolidated by two intramolecular N—H...O hydrogen bonds, which both generateS(6) rings. In the crystal, inversion dimers linked by pairs of C—H...O interactions generateR22(14) loops. The dimers are linked by further C—H...O interactions into (011) sheets.
Innovation and firm performance: the role of human resource management practices
Authors: Diaz-Fernandez Mirta , Bornay-Barrachina Mar , Lopez-Cabrales Alvaro
Published: April 2015

Purpose

– The purpose of this paper is to study the relationship between human resource (HR) practices and innovative performance in the Spanish industry. Specifically, the authors will focus on innovativeness, analysing the extent to which this capability is favoured by some human resource management (HRM) practices as investments on training and whether it is also affected by the use of full time and/or temporary workers.

Design/methodology/approach

– The authors propose the assessment of these relationships by means of the Spanish Survey of Industrial Strategic Behaviour. The authors focus the longitudinal analysis on the period 2001-2008, years of the highest economic growth in Spain during the last decades.

Findings

– The findings show that the most innovative firms are also the most competitive ones in terms of added value. Moreover, while a significant and positive relationship between the use of full-time workers and innovativeness is demonstrated, the role of temporary workers employees remains unclear. Finally, and surprisingly, training investments on new technologies, languages and data processes do not have any impact on innovativeness. The paper is closed with a discussion about some lessons the authors may learn from these wealthy years and the role played by HRM investments on firms.

Practical implications

– This study demonstrates the existence of two objectives that managers should seek to achieve. On one side, they should focus on innovation as a way of increasing firm performance. And, on the other side, managers should invest on specific training, in order to develop more innovative and profitable organizations.

Originality/value

– This paper proposes and tests a model where innovation mediates the relationships between HRM practices and performance. Such mediation would be a contribution to the strategic HRM field as very recent research call for the study of new mediators. Also, this paper employs panel data (2001-2008) for assessing these relationships. This is worthy because it is coherent with the idea of internal development of capabilities, instead of cross-sectional analyses and because the authors may infer causality with the study design, as it is demanded by researchers.
Empirical investigation of predictors of success in an MBA programme
Authors: Gupta Atul , Turek Joseph
Published: April 2015

Purpose

– The twofold purpose of this study was to determine if selected variables were predictors of: student performance in the MBA programme; and student performance on the MBA MFT exam.

Design/methodology/approach

– This study focuses on MBA graduates at a US university who have successfully completed the entire programme requirements. Real student performance data, collected from 2007 to 2012, were analysed using multivariate regression techniques.

Findings

– Results suggest that academic performance in an MBA programme is positively related to undergraduate grade point average (GPA) and GMAT exam score, two of the most common admissions criteria in use today. Additionally, performance in an initial skills-building course exhibits a strong positive correlation with performance in subsequent MBA courses. With respect to performance on the Major Field Test (MFT-MBA), our results indicate that students who do well in the MBA programme tend to score at a higher level than those with lower overall GPAs.

Research limitations/implications

– The research study was limited to MBA graduates at a business school in central Virginia. Further studies can determine whether differences in predictors of success in the MBA programme from those found in this study might exist.

Practical implications

– Results of this study provide practical implication for MBA programme curriculum development and assist MBA admission committees in designing MBA programme admission criteria.

Originality/value

– An extensive literature exists about the variables that influence the performance on the MFT exam at the undergraduate level. This is the first study to explore these relationships at the graduate level.