Stripe charge ordering in SrO-terminated SrTiO3(001) surfaces

The local electronic structure of the SrO-terminated SrTiO3(001) surface was explored using scanning tunneling microscopy. At low bias voltages in the empty states, a unidirectional structure with a periodicity of 3 unit cells, superimposed on a c(2 x 2) reconstructed structure, was found to develop along the crystallographic a axis. This structure indicates a charge-ordered stripe induced by carrier doping from oxygen vacancies in the SrO and the subsurface TiO2 planes. In the filled states, localized deep in-gap states were observed in addition to large energy gaps in the tunneling spectra. This result represents inelastic tunneling due to significant electron-lattice interaction associated with unidirectional lattice distortion in the SrO-terminated surface.Comment: 6 pages, 5 figures, accepted for publication in PR

Tardy posterior interosseous nerve palsy resulting from residual dislocation of the radial head in a Monteggia fracture: a case report

<p>Abstract</p> <p>Introduction</p> <p>We report an extremely rare case of tardy posterior interosseous nerve palsy that developed 40 years after unreduced anterior dislocation of the radial head in a Monteggia fracture.</p> <p>Case presentation</p> <p>A 46-year-old Asian woman was diagnosed with tardy posterior interosseous nerve palsy resulting from residual dislocation of the radial head in a Monteggia fracture. The patient remembered that she had sustained a fracture to the right elbow when she was 6 years old but could not remember the details of either the injury or its treatment. Intra-operatively, the posterior interosseous nerve was compressed at the radial head, wrapped around the medial side of the radial neck, and ran into the distorted supinator muscle, and was stretched. We therefore excised the radial head and performed neurolysis. The function of the right hand was normal at a follow-up examination 8 months after surgery.</p> <p>Conclusion</p> <p>We theorize that excessive repeated motion with loss of elasticity of surrounding tissues because of long-term dislocation of the radial head may cause delayed posterior interosseous nerve palsy. It is necessary to make an accurate diagnosis and render proper treatment when a Monteggia fracture occurs, making sure that the radial head does not remain dislocated, to avoid possible posterior interosseous nerve palsy due to excessive pronation and supination even several decades later.</p

Investigation of the crystallization process of CSD-ErBCO on IBAD-substrate via DSD approach

REBa$_{2}$Cu$_{3}$O$_{7-δ}$ (REBCO, RE: rare earth, such as Y and Gd) compounds have been extensively studied as a superconducting layer in coated conductors. Although ErBCO potentially has better superconducting properties than YBCO and GdBCO, little research has been made on it, especially in chemical solution deposition (CSD). In this work, ErBCO films were deposited on IBAD (ion-beam-assisted-deposition) substrates by CSD with low-fluorine solutions. The crystallization process was optimized to achieve the highest self-field critical current density (J$_{c}$) at 77 K. Commonly, for the investigation of a CSD process involving numerous process factors, one factor is changed keeping the others constant, requiring much time and cost. For more efficient investigation, this study adopted a novel design-of-experiment technique, definitive screening design (DSD), for the first time in CSD process. Two different types of solutions containing Er-propionate or Er-acetate were used to make two types of samples, Er-P and Er-A, respectively. Within the investigated range, we found that crystallization temperature, dew point, and oxygen partial pressure play a key role in Er-P, while the former two factors are significant for Er-A. DSD revealed these significant factors among six process factors with only 14 trials. Moreover, the DSD approach allowed us to create models that predict J$_{c}$ accurately. These models revealed the optimum conditions giving the highest J$_{c}$ values of 3.6 MA/cm$^{2}$ for Er-P and 3.0 MA/cm$^{2}$ for Er-A. These results indicate that DSD is an attractive approach to optimize CSD process

On the origin of interface states at oxide/III-nitride heterojunction interfaces

The energy spectrum of interface state density, D-it(E), was determined at oxide/III-N heterojunction interfaces in the entire band gap, using two complementary photo-electric methods: (i) photo-assisted capacitance-voltage technique for the states distributed near the midgap and the conduction band (CB) and (ii) light intensity dependent photo-capacitance method for the states close to the valence band (VB). In addition, the Auger electron spectroscopy profiling was applied for the characterization of chemical composition of the interface region with the emphasis on carbon impurities, which can be responsible for the interface state creation. The studies were performed for the AlGaN/GaN metal-insulator-semiconductor heterostructures (MISH) with Al2O3 and SiO2 dielectric films and AlxGa1-x layers with x varying from 0.15 to 0.4 as well as for an Al2O3/InAlN/GaN MISH structure. For all structures, it was found that: (i) D-it(E) is an U-shaped continuum increasing from the midgap towards the CB and VB edges and (ii) interface states near the VB exhibit donor-like character. Furthermore, D-it(E) for SiO2/AlxGa1-x/GaN structures increased with rising x. It was also revealed that carbon impurities are not present in the oxide/III-N interface region, which indicates that probably the interface states are not related to carbon, as previously reported. Finally, it was proven that the obtained D-it(E) spectrum can be well fitted using a formula predicted by the disorder induced gap state model. This is an indication that the interface states at oxide/III-N interfaces can originate from the structural disorder of the interfacial region. Furthermore, at the oxide/barrier interface we revealed the presence of the positive fixed charge (Q(F)) which is not related to D-it(E) and which almost compensates the negative polarization charge (Q(pol)(-))

Flat-Band Ferromagnetism in Organic Polymers Designed by a Computer Simulation

By coupling a first-principles, spin-density functional calculation with an exact diagonalization study of the Hubbard model, we have searched over various functional groups for the best case for the flat-band ferromagnetism proposed by R. Arita et al. [Phys. Rev. Lett. {\bf 88}, 127202 (2002)] in organic polymers of five-membered rings. The original proposal (poly-aminotriazole) has turned out to be the best case among the materials examined, where the reason why this is so is identified here. We have also found that the ferromagnetism, originally proposed for the half-filled flat band, is stable even when the band filling is varied away from the half-filling. All these make the ferromagnetism proposed here more experimentally inviting.Comment: 11 pages, 13figure

Weak ferromagnetism with very large canting in a chiral lattice: (pyrimidine)2FeCl2

The transition metal coordination compound (pyrimidine)2FeCl2 crystallizes in a chiral lattice, space group I 4_1 2 2 (or I4_3 2 2). Combined magnetization, Mossbauer spectroscopy and powder neutron diffraction studies reveal that it is a canted antiferromagnet below T_N = 6.4 K with an unusually large canting of the magnetic moments of 14 deg. from their general antiferromagnetic alignment, one of the largest reported to date. This results in weak ferromagnetism with a ferromagnetic component of 1 mu_B. The large canting is due to the interplay between the antiferromagnetic exchange interaction and the local single-ion anisotropy in the chiral lattice. The magnetically ordered structure of (pyrimidine)2FeCl2, however, is not chiral. The implications of these findings for the search of molecule based materials exhibiting chiral magnetic ordering is discussed.Comment: 6 pages, 5 figure

Towards the fabrication of phosphorus qubits for a silicon quantum computer

The quest to build a quantum computer has been inspired by the recognition of the formidable computational power such a device could offer. In particular silicon-based proposals, using the nuclear or electron spin of dopants as qubits, are attractive due to the long spin relaxation times involved, their scalability, and the ease of integration with existing silicon technology. Fabrication of such devices however requires atomic scale manipulation - an immense technological challenge. We demonstrate that it is possible to fabricate an atomically-precise linear array of single phosphorus bearing molecules on a silicon surface with the required dimensions for the fabrication of a silicon-based quantum computer. We also discuss strategies for the encapsulation of these phosphorus atoms by subsequent silicon crystal growth.Comment: To Appear in Phys. Rev. B Rapid Comm. 5 pages, 5 color figure

Novel diffusion mechanism on the GaAs(001) surface: the role of adatom-dimer interaction

Employing first principles total energy calculations we have studied the behavior of Ga and Al adatoms on the GaAs(001)-beta2 surface. The adsorption site and two relevant diffusion channels are identified. The channels are characterized by different adatom-surface dimer interaction. Both affect in a novel way the adatom migration: in one channel the diffusing adatom jumps across the surface dimers and leaves the dimer bonds intact, in the other one the surface dimer bonds are broken. The two channels are taken into account to derive effective adatom diffusion barriers. From the diffusion barriers we conclude a strong diffusion anisotropy for both Al and Ga adatoms with the direction of fastest diffusion parallel to the surface dimers. In agreement with experimental observations we find higher diffusion barriers for Al than for Ga.Comment: 4 pages, 2 figures, Phys. Rev. Lett. 79 (1997). Other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm

Effectiveness of communication campaign on iron deficiency anemia in Kyzyl-Orda region, Kazakhstan: a pilot study

<p>Abstract</p> <p>Background</p> <p>In 2004, wheat flour fortification (WFF) with iron was implemented in Kazakhstan as a public health strategy to increase the iron intake of all women of childbearing age and of children. In 2003, before starting the flour fortification program, a communication campaign on health education took place in a region with a high prevalence of iron deficiency anemia (IDA). The present study aimed to evaluate the prevalence of anemia, iron deficiency and IDA before and after the campaign. In addition, knowledge about IDA and its prevention, as well as awareness about fortified wheat flour, was assessed.</p> <p>Methods</p> <p>The subjects of the study were women aged 15-49 years and children aged 2-14 years. The study was carried out in urban and rural areas of Kyzyl-Orda region in 2003 before (March) and after (December) the campaign. Blood samples were collected in order to measure hemoglobin and serum ferritin. In March 80 women and 57 children in the urban area, and 41 women and 41 children in the rural area, participated in the IDA testing. The corresponding participants in December numbered 62, 52, 52, and 57, respectively. The impacts of the communications and information received by participants during the campaign was surveyed with a questionnaire for 195 women in March and 198 women in December including some who participated in the IDA testing.</p> <p>Results</p> <p>In March, the prevalence of anemia was 52.0% among 121 women and 58.1% among 98 children, and those with low iron reserve were 63.6%, 49.1% and IDA 40.5%, 11.0%, respectively. In December, the prevalence of anemia had significantly decreased among rural women (from 65.9% to 48.0%, p < 0.05) and among urban children (from 63.1% to 11.5%, p < 0.001). The prevalence of iron deficiency was significantly reduced among the children (from 51.1% to 24.8%, p < 0.001). IDA prevalence was meaningfully decreased among women in urban and combined areas (from 37.5% to 15.0% and 40.5 to 14.8%, respectively, p < 0.001) and among urban children (from 7.1% to 2.1%, p < 0.05). The surveys found that most women knew about IDA and its prevention and that the numbers were similar both in March and in December. The knowledge of the anti-anemic effect of wheat fortified flour improved significantly over the period of the campaign among women both in urban (from 48.5% to 80.9%, p < 0.001) and rural (from 69.8% to 88.6%, p < 0.001) areas.</p> <p>Conclusion</p> <p>The study demonstrated that the communication campaign before implementation of WFF program was effectively carried out, giving a biological impact on hematological indices.</p

The effectiveness of public health interventions to reduce the health impact of climate change:a systematic review of systematic reviews

Climate change is likely to be one of the most important threats to public health in the coming years. Yet despite the large number of papers considering the health impact of climate change, few have considered what public health interventions may be of most value in reducing the disease burden. We aimed to evaluate the effectiveness of public health interventions to reduce the disease burden of high priority climate sensitive diseases