Analytical solutions for the magnon frequencies at high-symmetry points of the Brillouin zone in anisotropic kagome antiferromagnets.

The knowledge of the magnon dispersion relations in antiferromagnetic materials with nontrivial spin textures has considerable interest to the understanding of magnonic and spintronic phenomena involving these materials. One particularly interesting nontrivial spin texture existing in several antiferromagnets has spins at an angle of 120° with the in-plane neighbors and arranged in kagome lattices. Here we present a spin-wave calculation for antiferromagnets with kagome spin lattices considering exchange and single-ion anisotropy interactions between the spins. The theory yields exact analytical expressions for the frequencies of magnons at high-symmetry points of the Brillouin zone, that can be readily use to obtain the interaction parameters from experimental data with one-and two-magnon inelastic light scattering. The analytical expressions are used to obtain the field parameters for the kagome lattice antiferromagnet L12-IrMn3from four experimentally measured frequencies. Both exchange field parameters are in reasonable agreement with the values obtained withab initiocalculations, while the anisotropy field is in very good agreement with the one calculated with atomistic spin models and Monte Carlo simulations.

Spin-to-charge conversion and interface-induced spin Hall magnetoresistance in yttrium iron garnet/metallic bilayers.

We report the investigation of spin-to-charge current interconversion process in hybrid structures of yttrium iron garnet (YIG)/metallic bilayers by means of two different experimental techniques: spin pumping effect (SPE) and spin Hall magnetoresistance (SMR). We demonstrate the evidence of a correlation between spin-to-charge conversion and SMR in bilayers of YIG/Pd, YIG/Pt, and YIG/IrMn. The correlation was verified directly in the spin Hall angles and the amplitudes of the voltage signals measured by the SPE and SMR techniques. The detection of SMR was carried out using the modulated magnetoresistance technique and lock-in amplifier detection. For these measurements, we present a simple model for the interpretation of the results. The results allow us to conclude that indeed the interface in the YIG/metallic bilayers has a dominant role in the spin-to-charge current conversion and SMR.

Use of a levonorgestrel 52-mg intrauterine system in the control of abnormal uterine bleeding in women with inherited bleeding disorders.

OBJECTIVE: To evaluate the efficacy of a levonorgestrel 52-mg intrauterine system (LNG 52-mg IUS) in controlling abnormal uterine bleeding and improving quality of life in women with inherited bleeding disorders. STUDY DESIGN: We assessed 20 participants laboratory diagnosed with inherited bleeding disorders, who presented with abnormal uterine bleeding and were registered in a Central Blood Center. The primary outcomes were menstrual bleeding volume and quality of life before and after LNG 52-mg IUS placement. We used the Pictorial Blood Loss Assessment Chart (PBAC) score for measuring menstrual bleeding and the Short Form-36 Health Survey to assess quality of life before and after LNG 52-mg IUS placement. We also conducted blood tests to evaluate the hematimetric level. Follow-up visits were conducted at 1, 3, 6, and 12 months after LNG 52-mg IUS placement. Statistical analyses were performed using the Friedman non-parametric test. RESULTS: The use of LNG 52-mg IUS reduced uterine bleeding in women with inherited bleeding disorders. The median PBAC score was higher before LNG 52-mg IUS placement than at 3, 6, and 12 months after placement (p < 0.001). The amenorrhea rate was 70% after 12 months. There was an improvement in all eight parameters of quality of life (p < 0.001). The mean hemoglobin, ferritin, and serum iron levels were also higher at 12 months than before LNG 52-mg IUS placement. CONCLUSION: LNG 52-mg IUS placement can effectively control abnormal uterine bleeding in women with inherited bleeding disorders and consequently improve their quality of life. IMPLICATIONS: The results from our study suggest that women with inherited bleeding disorders who present with heavy menstrual bleeding can benefit from the use of a levonorgestrel-releasing intrauterine system similar to women without bleeding disorders.

International Society on Thrombosis and Haemostasis core curriculum project: core competencies in clinical thrombosis and hemostasis.

UNLABELLED: Essentials The priority of ISTH was to establish a global core curriculum in thrombosis and hemostasis. International survey to determine competencies required for clinical specialists was carried out in the field. Competency framework provides a reference point for mapping and developing regional curricula. Core curriculum informs and links to a variety of ISTH educational materials. SUMMARY: Background The International Society on Thrombosis and Haemostasis (ISTH) identified the need for an international core curriculum on thrombosis and hemostasis for its society members and the larger thrombosis and hemostasis community. Aims The current research sought consensus on the core competencies required by medical doctors who are ready to practise as independent clinical specialists in thrombosis and hemostasis with the aim of developing a core clinical curriculum for specialists in the field. Method A draft list of competencies was developed by the Working Group and formed the basis of an online survey. ISTH members and the larger thrombosis and hemostasis community were asked to rate the importance of each competency, on a Likert scale, for clinical specialists in thrombosis and hemostasis. Results There were a total of 644 responses to the online survey with broad geographical representation. There was general agreement on what level of competency would be required for clinical specialists in thrombosis and hemostasis at the specified level of training. Conclusions Using the survey to gain consensus on the level of competency required by clinical specialists in the field of thrombosis and hemostasis enabled the development of a core clinical curriculum that has been endorsed by the ISTH Council. The curriculum will offer a framework and international reference that will be used by the society, by national and regional organizations, and for further research.

Spin-Current to Charge-Current Conversion and Magnetoresistance in a Hybrid Structure of Graphene and Yttrium Iron Garnet.

The use of graphene in spintronic devices depends, among other things, on its ability to convert a spin excitation into an electric charge signal, a phenomenon that requires a spin-orbit coupling (SOC). Here we report the observation of two effects that show the existence of SOC in large-area CVD grown single-layer graphene deposited on a single crystal film of the ferrimagnetic insulator yttrium iron garnet (YIG). The first is a magnetoresistance of graphene induced by the magnetic proximity effect with YIG. The second is the detection of a dc voltage along the graphene layer resulting from the conversion of the spin current generated by spin pumping from microwave driven ferromagnetic resonance into a charge current, which is attributed to the inverse Rashba-Edelstein effect.

Sustained magnetization oscillations in polyaniline-Fe3O4 nanocomposites.

We report experiments with polyaniline-Fe3O4 (PANI-Fe3O4) nanocomposites synthesized under several different conditions. With a reaction carried out at room temperature and assisted by intense ultra-violet (UV) irradiation, we observe sustained oscillations in the magnetization with a period of about 25 min. The oscillations are interpreted as the result of an oscillatory chemical reaction in which part of the Fe(+2) ions of magnetite, Fe3O4, are oxidized by the UV irradiation to form Fe(+3) so that a fraction of the magnetite content transforms into maghemite, γ-Fe2O3. Then, Fe(+3) ions at the nanoparticle surfaces are reduced and transformed back into Fe(+2), when acting as an oxidizing agent for polyaniline in the polymerization process. Since maghemite has smaller magnetization than magnetite, the oscillating chemical reaction results in the oscillatory magnetization. The observations are interpreted with the Lotka-Volterra nonlinear coupled equations with parameters that can be adjusted to fit very well the experimental data.

The molecular basis of low activity levels of coagulation factor VII: a Brazilian cohort.

Inherited factor VII (FVII) deficiency is the most common among the rare bleeding disorders. It is transmitted as an autosomal recessive inheritance, due to mutations in the FVII gene (F7). Molecular studies of FVII deficiency are rare in non-Caucasian populations. The aim of the study was to evaluate the molecular basis behind low levels of FVII activity (FVII:C) levels in a cohort of Brazilian patients. A total of 34 patients with low FVII levels were clinically evaluated and submitted to laboratory tests, among these, prothrombin time and FVII:C, with different thromboplastins. All exons and intron/exon boundaries of F7 were amplified and sequenced. A total of 14 genetic alterations were identified, of which six were described previously, c.1091G>A, c.1151C>T, c.-323_-313insCCTATATCCT, c.285G>A, c.525C>T, c.1238G>A and eight (54.0%) and eight were new, c.128G>A, c.252C>T, c.348G>A, c.417G>A, c.426G>A, c.745_747delGTG, c.843G>A and c.805+52C>T. In addition to the mutation c.1091G>A, known as FVII Padua, the mutation c.1151C>T also presented discrepant FVII:C levels when tested with human and rabbit brain thromboplastin. There was no association between phenotype and genotype. Most of the identified genetic alterations found were polymorphisms. Low levels of FVII:C in this population were mostly related to polymorphisms in F7 and associated with a mild clinical phenotype. Mutation c.1151C>T was associated with discrepant levels of FVII:C using different thromboplastins, such as reported with FVII Padua.

Epidemiology of recurrent venous thrombosis

Venous thrombosis, including deep vein thrombosis and pulmonary embolism, is a common disease that frequently recurs. Recurrence can be prevented by anticoagulants, but this comes at the risk of bleeding. Therefore, assessment of the risk of recurrence is important to balance the risks and benefits of anticoagulant treatment. This review briefly outlines what is currently known about the epidemiology of recurrent venous thrombosis, and focuses in more detail on potential new risk factors for venous recurrence. The general implications of these findings in patient management are discussed.

Epidemiology of recurrent venous thrombosis.

Venous thrombosis, including deep vein thrombosis and pulmonary embolism, is a common disease that frequently recurs. Recurrence can be prevented by anticoagulants, but this comes at the risk of bleeding. Therefore, assessment of the risk of recurrence is important to balance the risks and benefits of anticoagulant treatment. This review briefly outlines what is currently known about the epidemiology of recurrent venous thrombosis, and focuses in more detail on potential new risk factors for venous recurrence. The general implications of these findings in patient management are discussed.

Amplification of spin waves by thermal spin-transfer torque.

We observe amplification of spin-wave packets propagating along a film of single-crystal yttrium iron garnet subject to a transverse temperature gradient. The spin waves are excited and detected with standard techniques used in magnetostatic microwave delay lines in the 1-2 GHz frequency range. The amplification is attributed to the action of a thermal spin-transfer torque acting on the magnetization that opposes the relaxation and which is created by spin currents generated through the spin-Seebeck effect. The experimental data are interpreted with a spin-wave model that gives an amplification gain in very good agreement with the data.

JAK2V617F mutation in patients with thrombosis: to screen or not to screen?

INTRODUCTION: Thrombotic complications are a main concern in patients with myeloproliferative neoplasms. Recently, a gain-of-function mutation of the gene encoding the JAK2 tyrosine kinase that results in a valine-to-phenylalanine substitution at position 617 (V617F) has been described. Since the description of the JAK2-V617F mutation and its finding in patients with splanchnic vein thrombosis without an overt myeloproliferative neoplasm, many groups have studied the prevalence of this mutation in patients with unexplained venous and arterial thrombosis. METHODS: A literature search was made using the key words thrombosis, JAK2V617F mutation, myeloproliferative neoplasms, cerebral vein thrombosis and splanchnic vein thrombosis. RESULTS: JAK2V617F is frequent in patients with splanchnic vein thrombosis, but is rare in patients with venous thrombosis at other locations or with arterial thrombosis. CONCLUSION: Routine testing for JAK2V617F is not currently recommended for patients with unexplained thromboses, except for those with splanchnic vein thrombosis. In patients with cerebral vein thrombosis, the value of testing for JAK2V617F mutation is yet to be established.

Registry of inherited coagulopathies in Brazil: first report.

Inherited coagulopathies are bleeding disorders, which require treatment for life. Keeping an updated registry on these diseases is crucial for planning care, documenting prevalence of diseases and evaluating effectiveness of resources. We have analysed data from 26 treatment centres on coagulopathies in Brazil. Information included socio-demographic data, diagnosis of coagulopathies, severity of haemophilias A and B, presence and quantification of inhibitors in haemophilia, type of von Willebrand disease (VWD) and infection status for viral diseases. On 1 July 2007, there were 10 982 patients with inherited coagulopathies in Brazil, of which 6881 (62.7%) corresponded to haemophilia A, 1291 (11.7%) to haemophilia B, 2333 (21.2%) to VWD, 258 (2.4%) to other coagulopathies and 219 (2.0%) to undiagnosed bleeding disorders. Haemophilia A and B inhibitors were present in 9.9% and 1.9% of the patients, respectively. Human immunodeficiency virus infection was present is 6.5%, 4.8% and 1% of patients with haemophilia A, B and VWD, respectively. Hepatitis C virus infection was present in 34.9%, 29.7% and 12% of patients with haemophilia A, B and VWD, respectively. Infection by hepatitis B and human T-cell leukemia-lymphoma virus was also reported. This is the first report on the registry of patients with inherited coagulopathies in Brazil, supposed to be the third largest population of patients with haemophilia.

An overview of methods for detection of factor V Leiden and the prothrombin G20210A mutations.

Venous thromboembolism, represented by deep venous thrombosis and pulmonary embolism, is a common disease with high mortality and morbidity. Within the last 25 years, risk factors for venous thromboembolism have been linked to mutations in the genes of the coagulation/anticoagulation system. Factor V Leiden and the prothrombin G20210A mutations are the most prevalent inherited risk factors predisposing to venous thromboembolism in the Western world. Tests to detect these mutations are carried out when investigating a personal or family history of venous thromboembolism. At the present, there are several different methods available for the detection of these mutations in the laboratory. The choice of the method will depend on many variables. This article is aimed at reviewing the available methods for the detection of factor V Leiden and prothrombin G20210A mutations, their principle, applicability, advantages and disadvantages of use.

Mode locking of spin waves excited by direct currents in microwave nano-oscillators.

A spin-wave theory is presented which explains the frequency pulling and mode locking observed when two closely spaced spin-transfer nanometer-scale oscillators with slightly different frequencies are separately driven in the same magnetic thin film by spin-polarized carriers at high direct-current densities. The theory confirms recent experimental evidence that the origin of the phenomena lies in the nonlinear interaction between two overlapping spin waves excited in the magnetic nanostructure.