Epidemiología de la miastenia gravis en la provincia de Ourense (Galicia, noroeste de España) / Epidemiology of myasthenia gravis in the province of Ourense (Galicia, Spain)

Introducción: La miastenia gravis (MG) es un enfermedad autoinmune que afecta a la transmisión nerviosa a nivel de la unión neuromuscular causando debilidad muscular típicamente fluctuante. Los estudios epidemiológicos constatan un aumento de las tasas de prevalencia de la MG y es especialmente evidente en la población anciana.ObjetivoRealizar un estudio epidemiológico retrospectivo para conocer las tasas de incidencia y prevalencia en la provincia de Ourense (Galicia) caracterizada por el envejecimiento poblacional.Material y métodosLos pacientes fueron reclutados de nuestra base de datos clínica de enfermedades neuromusculares y a través de la búsqueda de pacientes con prescripción activa de bromuro de piridostigmina. La tasa de incidencia se estimó entre los años 2009-2018. Se estableció la fecha de prevalencia al 31/12/2018. El censo de la provincia de Ourense al 1/1/2019 era de 307.651 habitantes, de los que 96.544 (31,4%) tenían una edad ≥ de 65 años.ResultadosSe identificaron 80 casos de MG. La prevalencia fue de 260 casos/1.000.000 habitantes (IC95%: 202,7-316,4), y en la población ≥ 65 años de 517,9/1.000.000 habitantes (IC95%: 363,2-672,9). La incidencia acumulada en el periodo de estudio fue de 15,4 casos/1.000.000 habitantes-año. El inicio precoz (≤ 50 años) ocurrió en el 29,1% de los casos.ConclusiónLa prevalencia de la MG en nuestra área sanitaria es de las más altas entre las cifras previamente reportadas, y es una enfermedad muy prevalente en la población anciana. (AU)

Introduction: Myasthenia gravis (MG) is an autoimmune disease affecting nerve transmission at the level of the neuromuscular junction, and typically causes fluctuating muscle weakness. Epidemiological studies show an increase in MG prevalence, particularly among the older population.ObjectiveWe performed a retrospective epidemiological study to determine the incidence and prevalence of MG in the province of Ourense (Galicia, Spain), characterised by population ageing.Material and methodsPatients were selected from our clinical neuromuscular diseases database by searching for patients with an active prescription for pyridostigmine bromide. Incidence was estimated for the period 2009-2018. We calculated prevalence at 31/12/2018. According to census data for the province of Ourense, the population on 1/1/2019 was 307,651, of whom 96,544 (31.4%) were aged ≥ 65 years.ResultsWe identified 80 cases of MG, with a prevalence rate of 260 cases/1 000 000 population (95% CI, 202.7-316.4), rising to 517.9/1 000 000 population in those aged ≥ 65 (95% CI, 363.2-672.9). Cumulative incidence in the study period was 15.4 cases per 1 000 000 person-years. Early onset (≤ 50 years) was recorded in 29.1% of cases.ConclusionThe prevalence of MG in our health district is one of the highest published figures, and the disease is highly prevalent in the older population. (AU)

Risk of Cognitive Impairment in Patients With Parkinson's Disease With Visual Hallucinations and Subjective Cognitive Complaints.

BACKGROUND AND PURPOSE: Visual hallucinations (VH) and subjective cognitive complaints (SCC) are associated with cognitive impairment (CI) in Parkinson's disease. Our aims were to determine the association between VH and SCC and the risk of CI development in a cohort of patients with Parkinson's disease and normal cognition (PD-NC). METHODS: Patients with PD-NC (total score of >80 on the Parkinson's Disease Cognitive Rating Scale [PD-CRS]) recruited from the Spanish COPPADIS cohort from January 2016 to November 2017 were followed up after 2 years. Subjects with a score of ≥1 on domain 5 and item 13 of the Non-Motor Symptoms Scale at baseline (V0) were considered as "with SCC" and "with VH," respectively. CI at the 2-year follow-up (plus or minus 1 month) (V2) was defined as a PD-CRS total score of <81. RESULTS: At V0 (n=376, 58.2% males, age 61.14±8.73 years [mean±SD]), the frequencies of VH and SCC were 13.6% and 62.2%, respectively. VH were more frequent in patients with SCC than in those without: 18.8% (44/234) vs 4.9% (7/142), p<0.0001. At V2, 15.2% (57/376) of the patients had developed CI. VH presenting at V0 was associated with a higher risk of CI at V2 (odds ratio [OR]=2.68, 95% confidence interval=1.05-6.83, p=0.0.039) after controlling for the effects of age, disease duration, education, medication, motor and nonmotor status, mood, and PD-CRS total score at V0. Although SCC were not associated with CI at V2, presenting both VH and SCC at V0 increased the probability of having CI at V2 (OR=3.71, 95% confidence interval=1.36-10.17, p=0.011). CONCLUSIONS: VH were associated with the development of SCC and CI at the 2-year follow-up in patients with PD-NC.

Epidemiology of myasthenia gravis in the province of Ourense (Galicia, Spain).

INTRODUCTION: Myasthenia gravis (MG) is an autoimmune disease affecting nerve transmission at the level of the neuromuscular junction, and typically causes fluctuating muscle weakness. Epidemiological studies show an increase in MG prevalence, particularly among the older population. OBJECTIVE: We performed a retrospective epidemiological study to determine the incidence and prevalence of MG in the province of Ourense (Galicia, Spain), characterised by population ageing. MATERIAL AND METHODS: Patients were selected from our clinical neuromuscular diseases database by searching for patients with an active prescription for pyridostigmine bromide. Incidence was estimated for the period 2009-2018. We calculated prevalence at 31/12/2018. According to census data for the province of Ourense, the population on 1/1/2019 was 307 651, of whom 96 544 (31.4%) were aged ≥ 65 years. RESULTS: We identified 80 cases of MG, with a prevalence rate of 260 cases/1 000 000 population (95% CI, 202.7-316.4), rising to 517.9/1 000 000 population in those aged ≥ 65 (95% CI, 363.2-672.9). Cumulative incidence in the study period was 15.4 cases per 1 000 000 person-years. Early onset (≤ 50 years) was recorded in 29.1% of cases. CONCLUSION: The prevalence of MG in our health district is one of the highest published figures, and the disease is highly prevalent in the older population.

Risk of Cognitive Impairment in Patients With Parkinson’s Disease With Visual Hallucinations and Subjective Cognitive Complaints

Background@#and Purpose Visual hallucinations (VH) and subjective cognitive complaints (SCC) are associated with cognitive impairment (CI) in Parkinson’s disease. Our aims were to determine the association between VH and SCC and the risk of CI development in a cohort of patients with Parkinson’s disease and normal cognition (PD-NC). @*Methods@#Patients with PD-NC (total score of >80 on the Parkinson’s Disease Cognitive Rating Scale [PD-CRS]) recruited from the Spanish COPPADIS cohort from January 2016 to November 2017 were followed up after 2 years. Subjects with a score of ≥1 on domain 5 and item 13 of the Non-Motor Symptoms Scale at baseline (V0) were considered as “with SCC” and “with VH,” respectively. CI at the 2-year follow-up (plus or minus 1 month) (V2) was defined as a PD-CRS total score of <81. @*Results@#At V0 (n=376, 58.2% males, age 61.14±8.73 years [mean±SD]), the frequencies of VH and SCC were 13.6% and 62.2%, respectively. VH were more frequent in patients with SCC than in those without: 18.8% (44/234) vs 4.9% (7/142), p<0.0001. At V2, 15.2% (57/376) of the patients had developed CI. VH presenting at V0 was associated with a higher risk of CI at V2 (odds ratio [OR]=2.68, 95% confidence interval=1.05–6.83, p=0.039) after controlling for the effects of age, disease duration, education, medication, motor and nonmotor status, mood, and PD-CRS total score at V0. Although SCC were not associated with CI at V2, presenting both VH and SCC at V0 increased the probability of having CI at V2 (OR=3.71, 95% confidence interval=1.36–10.17, p=0.011). @*Conclusions@#VH were associated with the development of SCC and CI at the 2-year follow-up in patients with PD-NC.

Constipation Predicts Cognitive Decline in Parkinson's Disease: Results from the COPPADIS Cohort at 2-Year Follow-up and Comparison with a Control Group.

BACKGROUND: Constipation has been linked to cognitive impairment development in Parkinson's disease (PD). OBJECTIVE: Our aim was to analyze cognitive changes observed in PD patients and controls from a Spanish cohort with regards to the presence or not of constipation. METHODS: PD patients and controls recruited from 35 centers of Spain from the COPPADIS cohort from January 2016 to November 2017 were followed-up during 2 years. The change in cognitive status from baseline (V0) to 2-year follow-up was assessed with the PD-CRS (Parkinson's Disease Cognitive Rating Scale). Subjects with a score ≥1 on item 21 of the NMSS (Non-Motor Symptoms Scale) at baseline (V0) were considered as "with constipation". Regression analyses were applied for determining the contribution of constipation in cognitive changes. RESULTS: At V0, 39.7% (198/499) of PD patients presented constipation compared to 11.4% of controls (14/123) (p < 0.0001). No change was observed in cognitive status (PD-CRS total score) neither in controls without constipation (from 100.24±13.72 to 100.27±13.68; p = 0.971) and with constipation (from 94.71±10.96 to 93.93±13.03; p = 0.615). The PD-CRS total score decreased significantly in PD patients with constipation (from 89.14±15.36 to 85.97±18.09; p < 0.0001; Coehn's effect = -0.35) compared to patients without constipation (from 93.92±15.58 to 93.14±17.52; p = 0.250) (p = 0.018). In PD patients, to suffer from constipation at V0 was associated with a decrease in the PD-CRS total score from V0 to V2 (ß= -0.1; 95% CI, -4.36 - -0.27; p = 0.026) and having cognitive impairment at V2 (OR = 1.79; 95% CI, 1.01 - 3.17; p = 0.045). CONCLUSION: Constipation is associated with cognitive decline in PD patients but not in controls.

Staging Parkinson's Disease Combining Motor and Nonmotor Symptoms Correlates with Disability and Quality of Life.

INTRODUCTION: In a degenerative disorder such as Parkinson's disease (PD), it is important to establish clinical stages that allow to know the course of the disease. Our aim was to analyze whether a scale combining Hoehn and Yahr's motor stage (H&Y) and the nonmotor symptoms burden (NMSB) (assessed by the nonmotor symptoms scale (NMSS)) provides information about the disability and the patient's quality of life (QoL) with regard to a defined clinical stage. MATERIALS AND METHODS: Cross-sectional study in which 603 PD patients from the COPPADIS cohort were classified according to H&Y (1, stage I; 2, stage II; 3, stage III; 4, stage IV/V) and NMSB (A: NMSS = 0-20; B: NMSS = 21-40; C: NMSS = 41-70; D: NMSS ≥ 71) in 16 stages (HY.NMSB, from 1A to 4D). QoL was assessed with the PDQ-39SI, PQ-10, and EUROHIS-QOL8 and disability with the Schwab&England ADL (Activities of Daily Living) scale. RESULTS: A worse QoL and greater disability were observed at a higher stage of H&Y and NMSB (p < 0.0001). Combining both (HY.NMSB), patients in stages 1C and 1D and 2C and 2D had significantly worse QoL and/or less autonomy for ADL than those in stages 2A and 2B and 3A and 3B, respectively (p < 0.005; e.g., PDQ-39SI in 1D [n = 15] vs 2A [n = 101]: 28.6 ± 17.1 vs 7.9 ± 5.8; p < 0.0001). CONCLUSION: The HY.NMSB scale is simple and reflects the degree of patient involvement more accurately than the H&Y. Patients with a lower H&Y stage may be more affected if they have a greater NMS burden.

Mood in Parkinson's disease: From early- to late-stage disease.

BACKGROUND: Although depression is known to be frequent in Parkinson's disease (PD), it is unclear how mood can change and/or impact on patient's quality of life (QoL) over time. Our aim was to analyze the frequency of depression, mood related factors and the contribution of mood to a patient's QoL perception in regard to disease duration. METHODS: PD patients recruited from the COPPADIS cohort from January 2016 to November 2017 were included in this cross-sectional study. Three groups were defined: <5 years (Group A); from 5 to <10 years (Group B); ≥10 years (Group C). Analysis with well-planned linear regression models was conducted to determine how different factors contribute to mood (Beck Depression Inventory-II [BDI-II] as dependent variable), to health-related QoL (39-item Parkinson's Disease Questionnaire [PDQ-39SI] as dependent variable) and to global QoL (European Health Interview Survey - Quality of Life Eight-Item Index [EUROHIS-QOL8] as dependent variable). RESULTS: Six hundred and sixty-three PD patients (62.6 ± 8.9 years old, 59.6% males) were included: Group A, 50.1% (n = 332); Group B, 33.3% (n = 221) and Group C, 16.6% (n = 110). There were no differences between the three groups in terms of the frequency of depressive symptoms nor the frequency of depression type (major vs. minor vs. subthreshold) (p = 0.729). However, the unique percent variance of PDQ-39SI and EUROHIS-QOL8 explained by BDI-II total score was 2 (23.7%) and threefold (26.9%), respectively, in Group C compared to the other two groups. EUROHIS-QOL8 total score provided the highest unique contribution to mood (16.8%). CONCLUSIONS: Although depression-type frequency does not appear to change over time in PD; the contribution of mood on QoL perception is greater in patients with longer disease duration.

Quality of life and non-motor symptoms in Parkinson's disease patients with subthreshold depression.

BACKGROUND: The role of subthreshold depression (subD) in Parkinson's Disease (PD) is not clear. The present study aimed to compare the quality of life (QoL) in PD patients with subD vs patients with no depressive disorder (nonD). Factors related to subD were identified. MATERIAL AND METHODS: PD patients and controls recruited from the COPPADIS cohort were included. SubD was defined as Judd criteria. The 39-item Parkinson's disease Questionnaire (PDQ-39) and the EUROHIS-QOL 8-item index (EUROHIS-QOL8) were used to assess QoL. RESULTS: The frequency of depressive symptoms was higher in PD patients (n = 694) than in controls (n = 207) (p < 0.0001): major depression, 16.1% vs 7.8%; minor depression, 16.7% vs 7.3%; subD, 17.4% vs 5.8%. Both health-related QoL (PDQ-39; 18.1 ±â€¯12.8 vs 11.6 ±â€¯10; p < 0.0001) and global QoL (EUROHIS-QOL8; 3.7 ±â€¯0.5 vs 4 ±â€¯0.5; p < 0.0001) were significantly worse in subD (n = 120) than nonD (n = 348) PD patients. Non-motor Symptoms Scale (NMSS) total score was higher in subD patients (45.9 ±â€¯32 vs 29.1 ±â€¯25.8;p < 0.0001). Non-motor symptoms burden (NMSS;OR = 1.019;95%CI 1.011-1.028; p < 0.0001), neuropsychiatric symptoms (NPI; OR = 1.091; 95%CI 1.045-1.139; p < 0.0001), impulse control behaviors (QUIP-RS; OR = 1.035; 95%CI 1.007-1063; p = 0.013), quality of sleep (PDSS; OR = 0.991; 95%CI 0.983-0.999; p = 0.042), and fatigue (VAFS-physical; OR = 1.185; 95%CI 1.086-1.293; p < 0.0001; VAFS-mental; OR = 1.164; 95%CI 1.058-1.280; p = 0.0001) were related to subD after adjustment to age, disease duration, daily equivalent levodopa dose, motor status (UPDRS-III), and living alone. CONCLUSIONS: SubD is a frequent problem in patients with PD and is more prevalent in these patients than in controls. QoL is worse and non-motor symptoms burden is greater in subD PD patients.

Epidemiology of myasthenia gravis in the province of Ourense (Galicia, Spain). / Epidemiología de la miastenia gravis en la provincia de Ourense (Galicia, noroeste de España).

INTRODUCTION: Myasthenia gravis (MG) is an autoimmune disease affecting nerve transmission at the level of the neuromuscular junction, and typically causes fluctuating muscle weakness. Epidemiological studies show an increase in MG prevalence, particularly among the older population. OBJECTIVE: We performed a retrospective epidemiological study to determine the incidence and prevalence of MG in the province of Ourense (Galicia, Spain), characterised by population ageing. MATERIAL AND METHODS: Patients were selected from our clinical neuromuscular diseases database by searching for patients with an active prescription for pyridostigmine bromide. Incidence was estimated for the period 2009-2018. We calculated prevalence at 31/12/2018. According to census data for the province of Ourense, the population on 1/1/2019 was 307,651, of whom 96,544 (31.4%) were aged ≥ 65 years. RESULTS: We identified 80 cases of MG, with a prevalence rate of 260 cases/1 000 000 population (95% CI, 202.7-316.4), rising to 517.9/1 000 000 population in those aged ≥ 65 (95% CI, 363.2-672.9). Cumulative incidence in the study period was 15.4 cases per 1 000 000 person-years. Early onset (≤ 50 years) was recorded in 29.1% of cases. CONCLUSION: The prevalence of MG in our health district is one of the highest published figures, and the disease is highly prevalent in the older population.

[The prevalence of multiple sclerosis in the city of Ourense, Galicia, in the north-west of the Iberian Peninsula]. / Prevalencia de la esclerosis múltiple en la ciudad de Ourense, Galicia, noroeste de la Península Ibérica.

INTRODUCTION: Multiple sclerosis is an inflammatory neurodegenerative disease of the central nervous system, which mainly affects young people of working and reproductive age, and represents the first cause of non-traumatic disability in this age group of the population. A north-south latitude gradient is recognised, with prevalence rates increasing as we move away from the equator. This gradient probably represents the genetic predisposition transmitted from the Scandinavian regions through the Viking invasions and could presuppose an influence of the vitamin D deficit related to a lower number of hours of sunshine per year. AIMS: To determine the prevalence and incidence of multiple sclerosis in the city of Ourense, Galicia. PATIENTS AND METHODS: The latitude coordinate of the city of Ourense is 42° 34' N. A retrospective epidemiological study covering the period from 2002 to 2016 was conducted. The prevalence date was 31 December 2016. According to the latest census, the population of the city of Ourense was 105,892 on 1 January 2016. RESULTS: Altogether, 195 cases were recorded, representing a prevalence of 184.1 cases/100,000 inhabitants. In the period 2002-2016, 127 cases of multiple sclerosis were diagnosed, representing an average incidence of 7.86 cases/100,000 inhabitants/year. CONCLUSION: The city of Ourense has the highest prevalence rate of multiple sclerosis of those studied to date in the Iberian Peninsula, with a figure that brings it closer to the data reported in more northern areas under Nordic and Anglo-American influence.

TITLE: Prevalencia de la esclerosis múltiple en la ciudad de Ourense, Galicia, noroeste de la Península Ibérica.Introducción. La esclerosis múltiple es una enfermedad inflamatoria y neurodegenerativa del sistema nervioso central, que afecta fundamentalmente a personas jóvenes en edad laboral y reproductiva, y que representa la primera causa de discapacidad no traumática en este rango etario de la población. Se reconoce un gradiente de latitud norte-sur, con un aumento de las tasas de prevalencia a medida que nos alejamos del ecuador. Este gradiente probablemente representa la predisposición genética transmitida desde las regiones escandinavas a través de las invasiones vikingas y podría presuponer una influencia del déficit de vitamina D en relación con un menor número de horas de sol anuales. Objetivo. Determinar la prevalencia e incidencia de la esclerosis múltiple en la ciudad de Ourense, Galicia. Pacientes y métodos. La ciudad de Ourense tiene una coordenada de latitud de 42° 34' N. Se ha realizado un estudio epidemiológico retrospectivo que abarca desde 2002 a 2016. La fecha de prevalencia fue el 31 de diciembre de 2016. El censo de la población de la ciudad de Ourense a 1 de enero de 2016 era de 105.892 habitantes. Resultados. Se registraron 195 casos, lo que representa una prevalencia de 184,1 casos/100.000 habitantes. En el período 2002-2016 se diagnosticaron 127 casos de esclerosis múltiple, lo que supone una incidencia media de 7,86 casos/ 100.000 habitantes/año. Conclusión. La ciudad de Ourense presenta la tasa de prevalencia de esclerosis múltiple más alta de las estudiadas hasta la actualidad en la Península Ibérica, con una cifra que la aproxima a los datos comunicados en áreas más septentrionales de influencia nórdica y anglosajona.

Deterministic and time resolved thermo-magnetic switching in a nickel nanowire.

Heating a ferromagnetic material is often perceived as detrimental for most applications. This is indeed the case for modern nano-scaled spintronic devices which are operated solely (at least ideally) by an electric current. Heat is a by-product of the current-driven operation and it deteriorates many functionalities of the device. A large scientific and technological effort is devoted these days to avoid heat in modern magnetic nano devices. Here we show that heat can be used to provide an additional and useful degree of freedom in the control of the local magnetization at the nanoscale. In a ferromagnetic nanowire, temperature is used to induce a magnetic switching through a perfectly deterministic mechanism. The nucleation of the magnetic domain walls that triggers the switching can be achieved at a field considerably smaller than the nucleation field and, importantly, the exact moment of the magnetic switching can be pre-determined with nanosecond precision by controlling the power delivered locally to the switching area. With the help of micromagnetic simulations and a theoretical model, we provide an accurate explanation of how this deterministic thermo-magnetic switching operates. The concepts described in this work may lead to an increased functionality in magnetic nano-devices based on magnetic domain walls.

COPPADIS-2015 (COhort of Patients with PArkinson's DIsease in Spain, 2015): an ongoing global Parkinson's disease project about disease progression with more than 1000 subjects included. Results from the baseline evaluation.

BACKGROUND AND PURPOSE: In Parkinson's disease (PD), the course of the disorder is highly variable between patients. Well-designed, prospective studies for identifying PD progression biomarkers are necessary. Our aim was to show the results of baseline evaluations of an ongoing global PD project, COPPADIS-2015 (Cohort of Patients with PArkinson's DIsease in Spain, 2015). METHODS: This was an observational, descriptive, nationwide study (Spain). The recruitment period ended in October 2017. Baseline evaluation included more than 15 validated scales and complementary studies in a subgroup of participants. RESULTS: In total, 1174 subjects from 35 centres were considered valid for baseline analysis: 694 patients (62.6 ± 8.9 years old, 60.3% males), 273 caregivers (58.5 ± 11.9 years old, 31.8% males) and 207 controls (61 ± 8.3 years old, 49.5% males). The mean disease duration was 5.5 ± 4.4 years. Hoehn and Yahr stage was 1 or 2 in 90.7% of the patients whilst 33.9% and 18.1% of them presented motor fluctuations and dyskinesias, respectively. The mean Non-Motor Symptoms Scale total score was 45.4 ± 38.1, and 30.4% of the patients presented cognitive impairment, 16.1% major depression, 12.7% impulse control disorder, 7.2% compulsive behaviour, 57.2% pain and 13.2% falls. Compared to the control group, PD patients presented a significantly higher burden of non-motor symptoms and a worse quality of life. More than 300 subjects conducted complementary studies (serum biomarkers, genetic and neuroimaging). CONCLUSIONS: Parkinson's disease is a complex disorder and different non-motor symptoms are frequently present and are more prevalent than in controls. In real clinical practice it is important to ask for them.

[Isolated dysarthria and dysphagia as the presenting symptoms of simultaneous bilateral acute lagunar ischaemic stroke]. / Disartria y disfagia aisladas como forma de presentacion de un ictus isquemico agudo lacunar bilateral y simultaneo.

TITLE: Disartria y disfagia aisladas como forma de presentacion de un ictus isquemico agudo lacunar bilateral y simultaneo.

Geometrical control of pure spin current induced domain wall depinning.

We investigate the pure spin-current assisted depinning of magnetic domain walls in half ring based Py/Al lateral spin valve structures. Our optimized geometry incorporating a patterned notch in the detector electrode, directly below the Al spin conduit, provides a tailored pinning potential for a transverse domain wall and allows for a precise control over the magnetization configuration and as a result the domain wall pinning. Due to the patterned notch, we are able to study the depinning field as a function of the applied external field for certain applied current densities and observe a clear asymmetry for the two opposite field directions. Micromagnetic simulations show that this can be explained by the asymmetry of the pinning potential. By direct comparison of the calculated efficiencies for different external field and spin current directions, we are able to disentangle the different contributions from the spin transfer torque, Joule heating and the Oersted field. The observed high efficiency of the pure spin current induced spin transfer torque allows for a complete depinning of the domain wall at zero external field for a charge current density of [Formula: see text] A m-2, which is attributed to the optimal control of the position of the domain wall.

Large Hysteresis effect in Synchronization of Nanocontact Vortex Oscillators by Microwave Fields.

Current-induced vortex oscillations in an extended thin-film with point-contact geometry are considered. The synchronization of these oscillations with a microwave external magnetic field is investigated by a reduced order model that takes into account the dynamical effects associated with the significant deformation of the vortex structure produced by the current, which cannot be taken care of by using the standard rigid vortex theory. The complete phase diagram of the vortex oscillation dynamics is derived and it is shown that strong hysteretic behavior occurs in the synchronization with the external field. The complex nonlinear nature of the synchronization manifests itself also through the appearance of asymmetry in the locking frequency bands for moderate microwave field amplitudes. Predictions from the reduced order model are confirmed by full micromagnetic simulations.

Thermal effects on domain wall depinning from a single notch.

The statistical behavior of the domain wall depinning from a notch placed in a thin ferromagnetic wire is studied by means of a stochastic one-dimensional model which considers the wall as a rigid object inside a parabolic potential at room temperature. This analysis reveals the key role of thermal fluctuations on the current and field-induced domain wall depinning, and it allows for direct comparison with experiments in order to gain information on the nonadiabaticity degree of the spin torque.

Mirror domain structures induced by interlayer magnetic wall coupling.

We have found that during giant magnetoresistance measurements in approximately 10 x 10 mm(2) NiFe/Cu/Co continuous film spin-valve structures, the resistance value suddenly drops to its absolute minimum during the NiFe reversal. The results reveal that the alignment of all magnetic domains in the NiFe film follow exactly that of corresponding domains in the Co film for an appropriate applied field strength. This phenomenon is caused by trapping of the NiFe domain walls through the magnetostatic interaction with the Co domain-wall stray fields. Consequently, the interlayer domain-wall coupling induces a mirror domain structure in the magnetic trilayer.

Magnetic domain confinement by anisotropy modulation.

The spin configuration in a magnet is in general a "natural" consequence of both the intrinsic properties of the material and the sample dimensions. We demonstrate that this limitation can be overcome in a homogeneous ferromagnetic film by engineering an anisotropy contrast. Substrates with laterally modulated single-crystal and polycrystalline surface regions were used to induce selective epitaxial growth of a ferromagnetic Ni film. The resulting spatially varying magnetic anisotropy leads to regular perpendicular and in-plane magnetic domains, separated by a new type of magnetic wall---the "anisotropy constrained" magnetic wall.

Spin-engineering magnetic media.

The explosion in demand for increased data-storage density is driving the exploration of new magnetic media. Here we describe a new type of magnetic medium in which the spin configurations are engineered in chemically homogeneous magnetic films: regularly arranged in-plane and out-of-plane spin configurations are defined by altering the magnetic anisotropy. These spin-engineered media not only maintain the surface planarity but also the homogeneity of the magnetic materials, and our method is likely to find immediate application on account of its simplicity and ease of integration.

Observation of a bi-domain state and nucleation free switching in mesoscopic ring magnets.

We present the results of a study of the magnetic properties of an array of 34-nm thick Co(100) epitaxial ring magnets, with inner and outer diameters of d(in) = 1.3 microm and d(out) = 1.6 microm, respectively. Magnetic measurements and micromagnetic simulations show that a two step switching process occurs at high fields, indicating the existence of two different stable states. In addition to the vortex state, which occurs at intermediate fields, we have identified a new bi-domain state, which we term the onion state, corresponding to opposite circulation of the magnetization in each half of the ring. The onion state is stable at remanence and undergoes a simple and well characterized nucleation free switching.