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Sample records for abnormal magnetic structures

  1. Structurally abnormal human autosomes

    SciTech Connect

    1993-12-31

    Chapter 25, discusses structurally abnormal human autosomes. This discussion includes: structurally abnormal chromosomes, chromosomal polymorphisms, pericentric inversions, paracentric inversions, deletions or partial monosomies, cri du chat (cat cry) syndrome, ring chromosomes, insertions, duplication or pure partial trisomy and mosaicism. 71 refs., 8 figs.

  2. Structural Magnetic Resonance Imaging Can Identify Trigeminal System Abnormalities in Classical Trigeminal Neuralgia

    PubMed Central

    DeSouza, Danielle D.; Hodaie, Mojgan; Davis, Karen D.

    2016-01-01

    Classical trigeminal neuralgia (TN) is a chronic pain disorder that has been described as one of the most severe pains one can suffer. The most prevalent theory of TN etiology is that the trigeminal nerve is compressed at the root entry zone (REZ) by blood vessels. However, there is significant evidence showing a lack of neurovascular compression (NVC) for many cases of classical TN. Furthermore, a considerable number of patients who are asymptomatic have MR evidence of NVC. Since there is no validated animal model that reproduces the clinical features of TN, our understanding of TN pathology mainly comes from biopsy studies that have limitations. Sophisticated structural MRI techniques including diffusion tensor imaging provide new opportunities to assess the trigeminal nerves and CNS to provide insight into TN etiology and pathogenesis. Specifically, studies have used high-resolution structural MRI methods to visualize patterns of trigeminal nerve-vessel relationships and to detect subtle pathological features at the trigeminal REZ. Structural MRI has also identified CNS abnormalities in cortical and subcortical gray matter and white matter and demonstrated that effective neurosurgical treatment for TN is associated with a reversal of specific nerve and brain abnormalities. In conclusion, this review highlights the advanced structural neuroimaging methods that are valuable tools to assess the trigeminal system in TN and may inform our current understanding of TN pathology. These methods may in the future have clinical utility for the development of neuroimaging-based biomarkers of TN. PMID:27807409

  3. Frequency, prognosis and surgical treatment of structural abnormalities seen with magnetic resonance imaging in childhood epilepsy

    PubMed Central

    Mathern, Gary W.; Bronen, Richard A.; Fulbright, Robert K.; DiMario, Francis; Testa, Francine M.; Levy, Susan R.

    2009-01-01

    The epidemiology of lesions identified by magnetic resonance imaging (MRI), along with the use of pre-surgical evaluations and surgery in childhood-onset epilepsy patients has not previously been described. In a prospectively identified community-based cohort of children enrolled from 1993 to 1997, we examined (i) the frequency of lesions identified by MRI; (ii) clinical factors associated with ‘positive’ MRI scans; and (iii) the utilization of comprehensive epilepsy evaluations and neurosurgery. Of the original cohort of 613 children, 518 (85%) had usable MRI scans. Eighty-two (16%) had MRI abnormalities potentially relevant to epilepsy (‘positive’ scans). Idiopathic epilepsy syndromes were identified in 162 (31%) of whom 3% had positive scans. The remainder had non-idiopathic epilepsy syndromes of which 22% had positive MRI findings. Multiple logistic regression analysis identified non-idiopathic epilepsy and abnormal motor-sensory (neurological) examinations as predictors of a positive MRI scan. Of the non-idiopathic patients with normal neurological exams and who were not pharmacoresistant, 10% had positive MRI scans, including four patients with gliomas. Evaluations at comprehensive epilepsy centres occurred in 54 pharmacoresistant cases. To date 5% of the imaged cohort or 8% of non-idiopathic epilepsy patients have undergone surgical procedures (including vagal nerve stimulator implantation) to treat their epilepsy (n = 22) or for tumours (n = 6) without being drug resistant. Applying our findings to the general population of children in the USA, we estimate that there will be 127/1 000 000 new cases per year of pharmacoresistant epilepsy, and 52/1 000 000 childhood-onset epilepsy patients undergoing epilepsy evaluations. In addition, approximately 27/1 000 000 will have an epilepsy-related surgical procedure. These findings support recommendations for the use of MRI in evaluating newly diagnosed paediatric epilepsy patients, especially with non

  4. Frequency, Prognosis and Surgical Treatment of Structural Abnormalities Seen with Magnetic Resonance Imaging in Childhood Epilepsy

    ERIC Educational Resources Information Center

    Berg, Anne T.; Mathern, Gary W.; Bronen, Richard A.; Fulbright, Robert K.; DiMario, Francis; Testa, Francine M.; Levy, Susan R.

    2009-01-01

    The epidemiology of lesions identified by magnetic resonance imaging (MRI), along with the use of pre-surgical evaluations and surgery in childhood-onset epilepsy patients has not previously been described. In a prospectively identified community-based cohort of children enrolled from 1993 to 1997, we examined (i) the frequency of lesions…

  5. Abnormal Magnetic Field Effects on Electrogenerated Chemiluminescence

    NASA Astrophysics Data System (ADS)

    Pan, Haiping; Shen, Yan; Wang, Hongfeng; He, Lei; Hu, Bin

    2015-03-01

    We report abnormal magnetic field effects on electrogenerated chemiluminescence (MFEECL) based on triplet emission from the Ru(bpy)3Cl2-TPrA electrochemical system: the appearance of MFEECL after magnetic field ceases. In early studies the normal MFEECL have been observed from electrochemical systems during the application of magnetic field. Here, the abnormal MFEECL suggest that the activated charge-transfer [Ru(bpy)33+ … TPrA•] complexes may become magnetized in magnetic field and experience a long magnetic relaxation after removing magnetic field. Our analysis indicates that the magnetic relaxation can gradually increase the density of charge-transfer complexes within reaction region due to decayed magnetic interactions, leading to a positive component in the abnormal MFEECL. On the other hand, the magnetic relaxation facilitates an inverse conversion from triplets to singlets within charge-transfer complexes. The inverse triplet --> singlet conversion reduces the density of triplet light-emitting states through charge-transfer complexes and gives rise to a negative component in the abnormal MFEECL. The combination of positive and negative components can essentially lead to a non-monotonic profile in the abnormal MFEECL after ceasing magnetic field. Nevertheless, our experimental studies may reveal un-usual magnetic behaviors with long magnetic relaxation from the activated charge-transfer [Ru(bpy)33+ … TPrA•] complexes in solution at room temperature.

  6. Magnetic and structural properties of CaMn0.9Mo0.1O3 perovskite synthesized in abnormal glow discharge

    NASA Astrophysics Data System (ADS)

    Sarmiento Santos, Armando; Parra Vargas, Carlos Arturo; Supelano García, Ivan

    2015-09-01

    In this work we use the abnormal glow discharge (AGD) to produce the CaMn0.9Mo0.1O3 perovskite through decarbonize, calcination and sintering steps. Structural characterization was carry out by Rietveld refinement of X-ray diffraction on samples after sintering step. The magnetic properties was analysed through magnetization curves as a function of temperature for applied magnetic fields in the range of 20 Oe to 20 kOe by the ZFC-FC method and magnetization curves in function of the applied field at 50 K and 300 K temperatures. The CaMn0.9Mo0.1O3 perovskite was also produced by conventional method in resistive furnace and its behaviour was compared with those of the plasma synthesized. The X-ray analysis reveals that the samples produced by both methods crystalized in a Pnma structure, the lattice parameters change and one second phase appears when the AGD is applied in the last production steps. The magnetization measurements allow analysing the behaviour of the sample at low temperatures and comparing the magnetic transitions in the samples produced by both methods; these are influenced according to production method employed. The results shows that the use of AGD is an alternative method to produce ceramic materials, which reduced ostensibly the production time and allow to obtain similar magnetic and structural properties with respect to conventional method.

  7. Detection of Structural Abnormalities Using Neural Nets

    NASA Technical Reports Server (NTRS)

    Zak, M.; Maccalla, A.; Daggumati, V.; Gulati, S.; Toomarian, N.

    1996-01-01

    This paper describes a feed-forward neural net approach for detection of abnormal system behavior based upon sensor data analyses. A new dynamical invariant representing structural parameters of the system is introduced in such a way that any structural abnormalities in the system behavior are detected from the corresponding changes to the invariant.

  8. Effect of cobalt doping on the structural, magnetic and abnormal thermal expansion properties of NaZn13-type La(Fe1-xCox)11.4Al1.6 compounds.

    PubMed

    Zhao, Yuqiang; Huang, Rongjin; Li, Shaopeng; Wang, Wei; Jiang, Xingxing; Lin, Zheshuai; Li, Jiangtao; Li, Laifeng

    2016-07-27

    Cubic NaZn13-type La(Fe1-xCox)11.4Al1.6 compounds were synthesized and extensively explored through crystal structure and magnetization analyses. By optimizing the chemical composition, the isotropic abnormal properties of excellent zero and giant negative thermal expansion in a pure form were both found at different temperature ranges through room temperature. Moreover, the temperature regions with the remarkable abnormal thermal expansion (ATE) properties have been broadened which are controlled by the dM/dT. The present study demonstrates that the ATE behavior mainly depends on special structural and magnetic properties. These diverse properties suggest the high potential of La(Fe1-xCox)11.4Al1.6 for the development of abnormal expansion materials. PMID:27411397

  9. Reconciling abnormalities of brain network structure and function in schizophrenia.

    PubMed

    Fornito, Alex; Bullmore, Edward T

    2015-02-01

    Schizophrenia is widely regarded as a disorder of abnormal brain connectivity. Magnetic resonance imaging (MRI) suggests that patients show robust reductions of structural connectivity. However, corresponding changes in functional connectivity do not always follow, with increased functional connectivity being reported in many cases. Here, we consider different methodological and mechanistic accounts that might reconcile these apparently contradictory findings and argue that increased functional connectivity in schizophrenia likely represents a pathophysiological dysregulation of brain activity arising from abnormal neurodevelopmental wiring of structural connections linking putative hub regions of association cortex to other brain areas. Elucidating the pathophysiological significance of connectivity abnormalities in schizophrenia will be contingent on better understanding how network structure shapes and constrains function.

  10. Magnetic multilayer structure

    DOEpatents

    Herget, Philipp; O'Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2016-07-05

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  11. Abnormal thalamocortical structural and functional connectivity in juvenile myoclonic epilepsy

    PubMed Central

    O’Muircheartaigh, Jonathan; Vollmar, Christian; Barker, Gareth J.; Kumari, Veena; Symms, Mark R.; Thompson, Pam; Duncan, John S.; Koepp, Matthias J.

    2012-01-01

    Juvenile myoclonic epilepsy is the most common idiopathic generalized epilepsy, characterized by frequent myoclonic jerks, generalized tonic-clonic seizures and, less commonly, absences. Neuropsychological and, less consistently, anatomical studies have indicated frontal lobe dysfunction in the disease. Given its presumed thalamo–cortical basis, we investigated thalamo–cortical structural connectivity, as measured by diffusion tensor imaging, in a cohort of 28 participants with juvenile myoclonic epilepsy and detected changes in an anterior thalamo–cortical bundle compared with healthy control subjects. We then investigated task-modulated functional connectivity from the anterior thalamic region identified using functional magnetic resonance imaging in a task consistently shown to be impaired in this group, phonemic verbal fluency. We demonstrate an alteration in task-modulated connectivity in a region of frontal cortex directly connected to the thalamus via the same anatomical bundle, and overlapping with the supplementary motor area. Further, we show that the degree of abnormal connectivity is related to disease severity in those with active seizures. By integrating methods examining structural and effective interregional connectivity, these results provide convincing evidence for abnormalities in a specific thalamo–cortical circuit, with reduced structural and task-induced functional connectivity, which may underlie the functional abnormalities in this idiopathic epilepsy. PMID:23250883

  12. Abnormal magnetization behaviors in Sm-Ni-Fe-Cu alloys

    NASA Astrophysics Data System (ADS)

    Yang, W. Y.; Zhang, Y. F.; Zhao, H.; Chen, G. F.; Zhang, Y.; Du, H. L.; Liu, S. Q.; Wang, C. S.; Han, J. Z.; Yang, Y. C.; Yang, J. B.

    2016-06-01

    The magnetization behaviors in Sm-Ni-Fe-Cu alloys at low temperatures have been investigated. It was found that the hysteresis loops show wasp-waisted character at low temperatures, which has been proved to be related to the existence of multi-phases, the Fe/Ni soft magnetic phases and the CaCu5-type hard magnetic phase. A smooth-jump behavior of the magnetization is observed at T>5 K, whereas a step-like magnetization process appears at T<5 K. The CaCu5-type phase is responsible for such abnormal magnetization behavior. The magnetic moment reversal model with thermal activation is used to explain the relation of the critical magnetic field (Hcm) to the temperature (T>5 K). The reversal of the moment direction has to cross over an energy barrier of about 6.6×10-15 erg. The step-like jumps of the magnetization below 5 K is proposed to be resulted from a sharp increase of the sample temperature under the heat released by the irreversible domain wall motion.

  13. Abnormal brain structure in adults with Van der Woude syndrome.

    PubMed

    Nopoulos, P; Richman, L; Andreasen, N C; Murray, J C; Schutte, B

    2007-06-01

    Van der Woude syndrome (VWS) is an autosomal dominant disorder manifested in cleft lip and/or palate and lip pits. Isolated clefts of the lip and/or palate (ICLP) have both genotype and phenotype overlap with VWS. Subjects with ICLP have abnormalities in brain structure and function. Given the similarities between VWS and ICLP, the current study was designed to evaluate the pattern of brain structure of adults with VWS. Fourteen adults with VWS were compared to age- and gender-matched healthy controls. Brain structure was evaluated using magnetic resonance imaging. All subjects with VWS had enlarged volumes of the anterior regions of the cerebrum. Men with VWS had reduced volumes of the posterior cerebrum. Anterior cerebrum volume was negatively correlated with intelligent quotient in the subjects with VWS indicating that the enlargement of this brain region was 'pathologic.' The pattern of brain structure in VWS is nearly identical to those seen in ICLP. In addition, men are affected more severely. Pathologic enlargement of the tissue and a gender effect with men affected more severely are common features of neurodevelopmental disorders supporting the notion that the brain structure of VWS and ICLP may be because of abnormal brain development. PMID:17539900

  14. Structural Brain Abnormalities in Youth with Psychosis-Spectrum Symptoms

    PubMed Central

    Satterthwaite, Theodore D.; Wolf, Daniel H.; Calkins, Monica E.; Vandekar, Simon N.; Erus, Guray; Ruparel, Kosha; Roalf, David R.; Linn, Kristin A.; Elliott, Mark A.; Moore, Tyler M.; Hakonarson, Hakon; Shinohara, Russell T.; Davatzikos, Christos; Gur, Ruben C.; Gur, Raquel E.

    2016-01-01

    Importance Structural brain abnormalities are prominent in psychotic disorders including schizophrenia. However, it is unclear when aberrations emerge in the disease process, and if such deficits are present in association with less severe psychosis-spectrum (PS) symptoms in youth. Objective To investigate the presence of structural brain abnormalities in youth with PS symptoms. Design The Philadelphia Neurodevelopmental Cohort (PNC) is a prospectively accrued community-based sample of nearly 10,000 youths who received a structured psychiatric evaluation. A subsample of 1,601 subjects underwent neuroimaging including structural magnetic resonance imaging. Setting The PNC is a collaboration between The Children’s Hospital of Philadelphia and the Hospital of the University of Pennsylvania. Participants Youths ages 8–22 years identified through structured interview as having psychosis-spectrum features (PS, n=391), and typically developing comparison subjects without significant psychopathology (TD, n=400). Main Outcomes and Measures Measures of brain volume derived from T1-weighted structural neuroimaging at 3T. Analyses were conducted at global, regional, and voxelwise levels. Regional volumes were estimated with an advanced multi-atlas regional segmentation procedure; voxelwise volumetric analyses were conducted as well. Nonlinear developmental patterns were examined using penalized splines within a general additive model. PS symptom severity was summarized using factor analysis and evaluated dimensionally. Results Compared to the TD group, the PS group had diminished whole brain gray matter volume and expanded white matter volume. Voxelwise analyses revealed significantly lower gray matter volume in the medial temporal lobes as well as in frontal, temporal, and parietal cortex. Reduction of medial temporal lobe volume was correlated with PS symptom severity. Conclusions and Relevance Structural brain abnormalities that have been commonly reported in adults

  15. Patterns of Structural MRI Abnormalities in Deficit and Nondeficit Schizophrenia

    PubMed Central

    Galderisi, Silvana; Quarantelli, Mario; Volpe, Umberto; Mucci, Armida; Cassano, Giovanni Battista; Invernizzi, Giordano; Rossi, Alessandro; Vita, Antonio; Pini, Stefano; Cassano, Paolo; Daneluzzo, Enrico; De Peri, Luca; Stratta, Paolo; Brunetti, Arturo; Maj, Mario

    2008-01-01

    Negative symptoms of schizophrenia have generally been found in association with ventricular enlargement and prefrontal abnormalities. These relationships, however, have not been observed consistently, most probably because negative symptoms are heterogeneous and result from different pathophysiological mechanisms. The concept of deficit schizophrenia (DS) was introduced by Carpenter et al to identify a clinically homogeneous subgroup of patients characterized by the presence of primary and enduring negative symptoms. Findings of brain structural abnormalities reported by magnetic resonance imaging (MRI) studies focusing on DS have been mixed. The present study included 34 patients with DS, 32 with nondeficit schizophrenia (NDS), and 31 healthy comparison subjects, providing the largest set of MRI findings in DS published so far. The Schedule for the Deficit Syndrome was used to categorize patients as DS or NDS patients. The 2 patient groups were matched on age and gender and did not differ on clinical variables, except for higher scores on the negative dimension and more impaired interpersonal relationships in DS than in NDS subjects. Lateral ventricles were larger in NDS than in control subjects but were not enlarged in patients with DS. The cingulate gyri volume was smaller in NDS but not in DS patients as compared with healthy subjects. Both groups had smaller dorsolateral prefrontal cortex and temporal lobes than healthy subjects, but DS patients had significantly less right temporal lobe volume as compared with NDS patients. These findings do not support the hypothesis that DS is the extreme end of a severity continuum within schizophrenia. PMID:17728266

  16. Magnetic microhelix coil structures.

    PubMed

    Smith, Elliot J; Makarov, Denys; Sanchez, Samuel; Fomin, Vladimir M; Schmidt, Oliver G

    2011-08-26

    Together with the well-known ferro- and antiferromagnetic ordering, nature has created a variety of complex helical magnetic configurations. Here, we design and investigate three-dimensional microhelix coil structures that are radial-, corkscrew-, and hollow-bar-magnetized. The magnetization configurations of the differently magnetized coils are experimentally revealed by probing their specific dynamic response to an external magnetic field. Helix coils offer an opportunity to realize microscale geometries of the magnetic toroidal moment, observed so far only in bulk multiferroic materials. PMID:21929266

  17. Magnetic Microhelix Coil Structures

    NASA Astrophysics Data System (ADS)

    Smith, Elliot J.; Makarov, Denys; Sanchez, Samuel; Fomin, Vladimir M.; Schmidt, Oliver G.

    2011-08-01

    Together with the well-known ferro- and antiferromagnetic ordering, nature has created a variety of complex helical magnetic configurations. Here, we design and investigate three-dimensional microhelix coil structures that are radial-, corkscrew-, and hollow-bar-magnetized. The magnetization configurations of the differently magnetized coils are experimentally revealed by probing their specific dynamic response to an external magnetic field. Helix coils offer an opportunity to realize microscale geometries of the magnetic toroidal moment, observed so far only in bulk multiferroic materials.

  18. Hysterosalpingographic features of cervical abnormalities: acquired structural anomalies

    PubMed Central

    Zafarani, F; Shahrzad, G

    2015-01-01

    Cervical abnormalities may be congenital or acquired. Congenital cervical structural anomalies are relatively uncommon, whereas acquired cervical abnormalities are commonly seen in gynaecology clinics. Acquired abnormalities of the cervix can cause cervical factor infertility and recurrent spontaneous abortion. Various imaging tools have been used for evaluation of the uterine cavity and fallopian tubes. Hysterosalpingography (HSG) is a quick and minimally invasive tool for evaluation of infertility that facilitates visualization of the inner surfaces of the uterine cavity and fallopian tubes, as well as the cervical canal and isthmus. The lesions of the uterine cervix show various imaging manifestations on HSG such as narrowing, dilatation, filling defects, irregularities and diverticular projections. This pictorial review describes and illustrates the hysterosalpingographic appearances of normal variants and acquired structural abnormalities of the cervix. Accurate diagnosis of such cases is considered essential for optimal treatment. The pathological findings and radiopathological correlation will be briefly discussed. PMID:26111269

  19. Imprinting artificial magnetic structures.

    SciTech Connect

    Lohstroh, W.

    1998-09-25

    Recently we created La/Fe multilayers with a helical magnetic structure imprinted from the conditions of growth rather than by the magnetic interactions between layers. Each sublayer was 30{angstrom} thick, and during deposition the sample was rotated in an external field of 3 Oe. a field strong enough to magnetize the Fe layer being deposited but not sufficient to perturb the magnetization of the Fe layers already grown. As a result adjacent Fe layers formed a helical structure with a chirality and periodicity determined by the rotational direction and speed of the substrate and the rate of deposition. Following this discovery, an extensive set of experiments (mainly using Kerr effect magnetometry and polarized neutron reflectivity) was undertaken to ascertain the stability of imprinted magnetic structures, and to understand the onset of magnetization during growth. La/Fe imprinted helical magnetic structures (of different La and Fe thicknesses) were found to be stable in time and to be permanently erased only by magnetic fields larger than 90 Oe.

  20. [Consequences of abnormalities of chromosome structure in domestic animals].

    PubMed

    Popescu, C P

    1990-01-01

    Abnormalities in chromosome structure generally have no phenotypic expression but are very often associated with reproductive disorders. In cattle, sheep and goats, the robertsonian translocation seems to be the most frequent abnormality of chromosome structure. In the pig, reciprocal translocations are very common. The accumulation of data on the frequency of such abnormalities and their effects on reproductive performance prompted an evaluation of their economic consequences in cattle and pigs. In cattle, because of the negative effect of 1/29 translocation, an eradication program, based on the removal of carrier bulls from artificial insemination centers was established. In pig, the main effect of the reciprocal translocations was a reduction in the number of offspring, up to 50%, thus representing a considerable economic loss. PMID:2206288

  1. Brief Report: Brain Mechanisms in Autism: Functional and Structural Abnormalities.

    ERIC Educational Resources Information Center

    Minshew, Nancy J.

    1996-01-01

    This paper summarizes results of research on functional and structural abnormalities of the brain in autism. The current concept of causation is seen to involve multiple biologic levels. A consistent profile of brain function and dysfunction across methods has been found and specific neuropathologic findings have been found; but some research…

  2. Magnetic structure of holmium

    NASA Astrophysics Data System (ADS)

    Pechan, M. J.; Stassis, C.

    1984-03-01

    The magnetic structure of high purity single crystals of holmium has been studied by neutron diffraction techniques. Although the general characteristics of the magnetic structure have been found to agree with earlier measurements, some discrepancies have been resolved and new features have been observed. The magnetic form factor has been measured and compared with relativistic atomic calculations. The low temperature structure (T<20 K) is that of a conical ferromagnet with wave vector (1/6)(2π/c) along the c axis. The basal plane moment is 9.7 μB and the c-axis ferromagnetic component is 1.6 μB at T=6 K. Bunching of the basal plane moments around the easy hexagonal direction has been observed below T=50 K. Evidence for asphericity in the magnetization density is presented and discussed. The wave vector of the basal plane modulation decreases monotonically with temperature in general accordance with the Elliott-Wedgewood theory. Several inflection points were observed, however, which correspond to commensurability with the chemical lattice. The measured temperature dependence of the c- and a-axis lattice constants shows significant magnetostriction. The possibility of a c-axis modulated moment is discussed.

  3. Connectivity and functional profiling of abnormal brain structures in pedophilia

    PubMed Central

    Poeppl, Timm B.; Eickhoff, Simon B.; Fox, Peter T.; Laird, Angela R.; Rupprecht, Rainer; Langguth, Berthold; Bzdok, Danilo

    2015-01-01

    Despite its 0.5–1% lifetime prevalence in men and its general societal relevance, neuroimaging investigations in pedophilia are scarce. Preliminary findings indicate abnormal brain structure and function. However, no study has yet linked structural alterations in pedophiles to both connectional and functional properties of the aberrant hotspots. The relationship between morphological alterations and brain function in pedophilia as well as their contribution to its psychopathology thus remain unclear. First, we assessed bimodal connectivity of structurally altered candidate regions using meta-analytic connectivity modeling (MACM) and resting-state correlations employing openly accessible data. We compared the ensuing connectivity maps to the activation likelihood estimation (ALE) maps of a recent quantitative meta-analysis of brain activity during processing of sexual stimuli. Second, we functionally characterized the structurally altered regions employing meta-data of a large-scale neuroimaging database. Candidate regions were functionally connected to key areas for processing of sexual stimuli. Moreover, we found that the functional role of structurally altered brain regions in pedophilia relates to nonsexual emotional as well as neurocognitive and executive functions, previously reported to be impaired in pedophiles. Our results suggest that structural brain alterations affect neural networks for sexual processing by way of disrupted functional connectivity, which may entail abnormal sexual arousal patterns. The findings moreover indicate that structural alterations account for common affective and neurocognitive impairments in pedophilia. The present multi-modal integration of brain structure and function analyses links sexual and nonsexual psychopathology in pedophilia. PMID:25733379

  4. Abnormal brain magnetic resonance imaging in two patients with Smith-Magenis syndrome.

    PubMed

    Maya, Idit; Vinkler, Chana; Konen, Osnat; Kornreich, Liora; Steinberg, Tamar; Yeshaya, Josepha; Latarowski, Victoria; Shohat, Mordechai; Lev, Dorit; Baris, Hagit N

    2014-08-01

    Smith-Magenis syndrome (SMS) is a clinically recognizable contiguous gene syndrome ascribed to an interstitial deletion in chromosome 17p11.2. Seventy percent of SMS patients have a common deletion interval spanning 3.5 megabases (Mb). Clinical features of SMS include characteristic mild dysmorphic features, ocular anomalies, short stature, brachydactyly, and hypotonia. SMS patients have a unique neurobehavioral phenotype that includes intellectual disability, self-injurious behavior and severe sleep disturbance. Little has been reported in the medical literature about anatomical brain anomalies in patients with SMS. Here we describe two patients with SMS caused by the common deletion in 17p11.2 diagnosed using chromosomal microarray (CMA). Both patients had a typical clinical presentation and abnormal brain magnetic resonance imaging (MRI) findings. One patient had subependymal periventricular gray matter heterotopia, and the second had a thin corpus callosum, a thin brain stem and hypoplasia of the cerebellar vermis. This report discusses the possible abnormal MRI images in SMS and reviews the literature on brain malformations in SMS. Finally, although structural brain malformations in SMS patients are not a common feature, we suggest baseline routine brain imaging in patients with SMS in particular, and in patients with chromosomal microdeletion/microduplication syndromes in general. Structural brain malformations in these patients may affect the decision-making process regarding their management.

  5. Transient global amnesia: hippocampal magnetic resonance imaging abnormalities.

    PubMed

    Alberici, Elisa; Pichiecchio, Anna; Caverzasi, Eduardo; Farina, Lisa Maria; Persico, Alessandra; Cavallini, Anna; Bastianello, Stefano

    2008-01-01

    Transient global amnesia (TGA) is an episodic dysfunction of declarative memory that usually resolves within 12 hours and whose underlying pathophysiological mechanisms are still unclear. Recent studies, on the basis of transient focal high-signal abnormalities in the hippocampus on diffusion-weighted imaging (DWI), suggest involvement of memory circuits in the temporo-mesial region. Out of a total of 65 patients presenting with acute or subacute TGA between May 2004 and May 2008, we retrospectively analysed 21 in whom a DWI sequence was performed. Five patients showed a focal hippocampal signal alteration both on DWI and on conventional T2; this alteration was no longer detectable on follow-up MRI two months later. The presence of transient DWI and T2 alterations in the hippocampal formation suggests that TGA could have a multifactorial, non-vascular aetiology. The presence of local susceptibility to neuronal metabolic stress emerges as a likely hypothesis.

  6. Abnormalities of vascular structure and function in pediatric hypertension.

    PubMed

    Urbina, Elaine M

    2016-07-01

    Hypertension is associated with adverse cardiovascular (CV) events in adults. Measures of vascular structure and function, including increased carotid intima-media thickness (cIMT) and elevated arterial stiffness predict hard CV events in adulthood. Newer data suggest that abnormalities in target organ damage are occurring in adolescents and young adults with high blood pressure. In this review, we discuss the techniques for measuring vascular dysfunction in young people and the evidence linking blood pressure levels to this type of target organ damage.

  7. Structural Brain Abnormalities in Patients with Schizophrenia and 22q11 Deletion Syndrome

    PubMed Central

    Chow, Eva W.C.; Zipursky, Robert B.; Mikulis, David J.; Bassett, Anne S.

    2012-01-01

    Background 22q11 Deletion Syndrome is a genetic syndrome associated with an increased risk for developing schizophrenia. Brain abnormalities have been reported in 22q11 Deletion Syndrome, but little is known about whether differences in brain structure underlie the psychotic disorders associated with this syndrome. In the current study, we used magnetic resonance imaging to characterize the structural brain abnormalities found in adults who have both 22q11 Deletion Syndrome and schizophrenia. Methods Magnetic resonance imaging brain scans of 14 adults (7 male, 7 female) with 22q11 Deletion Syndrome and schizophrenia and 14 age- and gender-matched healthy volunteers were analyzed to derive measures of gray matter, white matter, and cerebrospinal fluid. Differences between the two groups were tested using student t tests. Results 22q11 Deletion Syndrome and schizophrenia subjects had significantly smaller total gray matter volume (t = 2.88, p < .01) and larger lateral ventricles (t = 4.08, p < .001) than healthy controls. Gray matter deficits were most prominent in the frontal and temporal lobes. Total white matter volumes did not differ between the two groups. Conclusions Findings from this 22q11 Deletion Syndrome and schizophrenia study are similar to those reported in other patients with schizophrenia, but only partially consistent with those reported in nonpsychotic children with 22q11 Deletion Syndrome. 22q11 Deletion Syndrome may provide a valuable genetic neurodevelop-mental model for investigating the relationship between abnormalities in brain development and the expression of schizophrenia. PMID:11839363

  8. Abnormalities in structural covariance of cortical gyrification in schizophrenia.

    PubMed

    Palaniyappan, Lena; Park, Bert; Balain, Vijender; Dangi, Raj; Liddle, Peter

    2015-07-01

    The highly convoluted shape of the adult human brain results from several well-coordinated maturational events that start from embryonic development and extend through the adult life span. Disturbances in these maturational events can result in various neurological and psychiatric disorders, resulting in abnormal patterns of morphological relationship among cortical structures (structural covariance). Structural covariance can be studied using graph theory-based approaches that evaluate topological properties of brain networks. Covariance-based graph metrics allow cross-sectional study of coordinated maturational relationship among brain regions. Disrupted gyrification of focal brain regions is a consistent feature of schizophrenia. However, it is unclear if these localized disturbances result from a failure of coordinated development of brain regions in schizophrenia. We studied the structural covariance of gyrification in a sample of 41 patients with schizophrenia and 40 healthy controls by constructing gyrification-based networks using a 3-dimensional index. We found that several key regions including anterior insula and dorsolateral prefrontal cortex show increased segregation in schizophrenia, alongside reduced segregation in somato-sensory and occipital regions. Patients also showed a lack of prominence of the distributed covariance (hubness) of cingulate cortex. The abnormal segregated folding pattern in the right peri-sylvian regions (insula and fronto-temporal cortex) was associated with greater severity of illness. The study of structural covariance in cortical folding supports the presence of subtle deviation in the coordinated development of cortical convolutions in schizophrenia. The heterogeneity in the severity of schizophrenia could be explained in part by aberrant trajectories of neurodevelopment.

  9. Cardiac ultrasonography in structural abnormalities and arrhythmias. Recognition and treatment.

    PubMed Central

    Brook, M M; Silverman, N H; Villegas, M

    1993-01-01

    Fetal cardiac ultrasonography has become an important tool in the evaluation of fetuses at risk for cardiac anomalies. It can both guide prenatal treatment and assist the management and timing of delivery. We recommend that a fetal echocardiogram be done when there is a family history of congenital heart disease; maternal disease that may affect the fetus; a history of maternal drug use, either therapeutic or illegal; evidence of other fetal abnormalities; or evidence of fetal hydrops. The optimal timing of evaluation is 18 to 22 weeks' gestation. An entire range of structural cardiac defects can be visualized prenatally, including atrioventricular septal defect, ventricular septal defect, cardiomyopathy, ventricular outlet obstruction, and complex cardiac defects. The outcome for a fetus with a recognized abnormality is unfavourable, with less than 50% surviving the neonatal period. Fetal cardiac arrhythmias are also a common occurrence, 15% in the series described here. Premature atrial or ventricular contractions are most commonly seen and usually require no treatment. Supraventricular tachycardia can result in hydrops and require in utero treatment to prevent fetal demise. Complete heart block, particularly in association with structural heart disease, has a poor prognosis for fetal survival. Images PMID:8236970

  10. Cerebral abnormalities: use of calculated T1 and T2 magnetic resonance images for diagnosis

    SciTech Connect

    Mills, C.M.; Crooks, L.E.; Kaufman, L.; Brant-Zawadzki, M.

    1984-01-01

    The potential clinical importance of T1 and T2 relaxation times in distinguishing normal and pathologic tissue with magnetic resonance (MR) is discussed and clinical examples of cerebral abnormalities are given. Five patients with cerebral infarction, 15 with multiple sclerosis, two with Wilson disease, and four with tumors were imaged. Hemorrhagic and ischemic cerebrovascular accidents were distinguished using the spin echo technique. In the patients with multiple sclerosis, lesions had prolonged T1 and T2 times, but the definition of plaque was limited by spatial resolution. No abnormalities in signal intensity were seen in the patient with Wilson disease who was no longer severly disabled; abnormal increased signal intensity in the basal ganglia was found in the second patient with Wilson disease. Four tumors produced abnormal T1 and T2 relaxation times but these values alone were not sufficient for tumor characterization.

  11. Structure of magnetic field lines

    NASA Astrophysics Data System (ADS)

    Golmankhaneh, Ali Khalili; Golmankhaneh, Alireza Khalili; Jazayeri, Seyed Masud; Baleanu, Dumitru

    2012-02-01

    In this paper the Hamiltonian structure of magnetic lines is studied in many ways. First it is used vector analysis for defining the Poisson bracket and Casimir variable for this system. Second it is derived Pfaffian equations for magnetic field lines. Third, Lie derivative and derivative of Poisson bracket is used to show structure of this system. Finally, it is shown Nambu structure of the magnetic field lines.

  12. Anisotropically structured magnetic aerogel monoliths

    NASA Astrophysics Data System (ADS)

    Heiligtag, Florian J.; Airaghi Leccardi, Marta J. I.; Erdem, Derya; Süess, Martin J.; Niederberger, Markus

    2014-10-01

    Texturing of magnetic ceramics and composites by aligning and fixing of colloidal particles in a magnetic field is a powerful strategy to induce anisotropic chemical, physical and especially mechanical properties into bulk materials. If porosity could be introduced, anisotropically structured magnetic materials would be the perfect supports for magnetic separations in biotechnology or for magnetic field-assisted chemical reactions. Aerogels, combining high porosity with nanoscale structural features, offer an exceptionally large surface area, but they are difficult to magnetically texture. Here we present the preparation of anatase-magnetite aerogel monoliths via the assembly of preformed nanocrystallites. Different approaches are proposed to produce macroscopic bodies with gradient-like magnetic segmentation or with strongly anisotropic magnetic texture.Texturing of magnetic ceramics and composites by aligning and fixing of colloidal particles in a magnetic field is a powerful strategy to induce anisotropic chemical, physical and especially mechanical properties into bulk materials. If porosity could be introduced, anisotropically structured magnetic materials would be the perfect supports for magnetic separations in biotechnology or for magnetic field-assisted chemical reactions. Aerogels, combining high porosity with nanoscale structural features, offer an exceptionally large surface area, but they are difficult to magnetically texture. Here we present the preparation of anatase-magnetite aerogel monoliths via the assembly of preformed nanocrystallites. Different approaches are proposed to produce macroscopic bodies with gradient-like magnetic segmentation or with strongly anisotropic magnetic texture. Electronic supplementary information (ESI) available: Digital photographs of dispersions and gels with different water-to-ethanol ratios; magnetic measurements of an anatase aerogel containing 0.25 mol% Fe3O4 nanoparticles; XRD patterns of the iron oxide and

  13. Structural abnormalities at neuromuscular synapses lacking multiple syntrophin isoforms.

    PubMed

    Adams, Marvin E; Kramarcy, Neal; Fukuda, Taku; Engel, Andrew G; Sealock, Robert; Froehner, Stanley C

    2004-11-17

    The syntrophins are modular adapter proteins that function by recruiting signaling molecules to the cytoskeleton via their direct association with proteins of the dystrophin protein family. We investigated the physiological function of beta2-syntrophin by generating a line of mice lacking this syntrophin isoform. The beta2-syntrophin null mice show no overt phenotype, or muscular dystrophy, and form structurally normal neuromuscular junctions (NMJs). To determine whether physiological consequences caused by the lack of beta2-syntrophin were masked by compensation from the alpha-syntrophin isoform, we crossed these mice with our previously described alpha-syntrophin null mice to produce mice lacking both isoforms. The alpha/beta2-syntrophin null mice have NMJs that are structurally more aberrant than those lacking only alpha-syntrophin. The NMJs of the alpha/beta2-syntrophin null mice have fewer junctional folds than either parent strain, and the remaining folds are abnormally shaped with few openings to the synaptic space. The levels of acetylcholine receptors are reduced to 23% of wild type in mice lacking both syntrophin isoforms. Furthermore, the alpha/beta2-syntrophin null mice ran significantly shorter distances on voluntary exercise wheels despite having normal neuromuscular junction transmission as determined by micro-electrode recording of endplate potentials. We conclude that both alpha-syntrophin and beta2-syntrophin play distinct roles in forming and maintaining NMJ structure and that each syntrophin can partially compensate for the loss of the other.

  14. Abnormal findings on knee magnetic resonance imaging in asymptomatic NBA players.

    PubMed

    Walczak, Brian E; McCulloch, Patrick C; Kang, Richard W; Zelazny, Anthony; Tedeschi, Fred; Cole, Brian J

    2008-01-01

    The purpose of this study was to evaluate the knees of asymptomatic National Basketball Association (NBA) players via magnetic resonance imaging (MRI) and confirm or dispute findings reported in the previous literature. It is thought that a variety of significant abnormalities affecting the knee exist in asymptomatic patients and that these findings can be accurately identified on MRI. Two months prior to the 2005 season, bilateral knee MRI examinations of 14 asymptomatic NBA players (28 knees) were evaluated for abnormalities of the articular cartilage, menisci, and patellar and quadriceps tendons. The presence of joint effusion, subchondral edema, and cystic lesions and the integrity of the collateral and cruciate ligaments were also assessed.

  15. Magnetic cellulose-derivative structures

    DOEpatents

    Walsh, Myles A.; Morris, Robert S.

    1986-09-16

    Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorbtion agents can be incorporated during the manufacture of the structure.

  16. Magnetic cellulose-derivative structures

    DOEpatents

    Walsh, M.A.; Morris, R.S.

    1986-09-16

    Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorption agents can be incorporated during the manufacture of the structure. 3 figs.

  17. Abnormal Spinal Cord Magnetic Resonance Signal: Approach to the Differential Diagnosis.

    PubMed

    Morales, Humberto; Betts, Aaron

    2016-10-01

    T2-hyperintense signal abnormalities within the spinal cord on magnetic resonance imaging can evoke a broad differential diagnosis and can present a diagnostic dilemma. Here, we review and provide a succinct and relevant differential diagnosis based on imaging patterns and anatomical or physiopathologic correlation. Clues and imaging pearls are provided focusing on inflammatory, infectious, demyelinating, vascular, and metabolic involvement of the spinal cord. PMID:27616311

  18. Neuroimaging of schizophrenia: structural abnormalities and pathophysiological implications

    PubMed Central

    Buckley, Peter F

    2005-01-01

    Schizophrenia, once considered a psychological malady devoid of any organic brain substrate, has been the focus of intense neuroimaging research. Findings reveal mild but generalized tissue loss as well as more selective focal loss. It is unclear whether these abnormalities reflect neurodevelopmental or neurodegenerative processes, or some combination of each; current evidence favors a preponderance of neurodevelopmental abnormalities. The pattern of brain abnormalities is also influenced by environmental and genetic risk factors, as well as by the course (and possibly even treatment) of this illness. These findings are described in this article. PMID:18568069

  19. Magnetic field structure of Mercury

    NASA Astrophysics Data System (ADS)

    Hiremath, K. M.

    2012-04-01

    Recently planet Mercury - an unexplored territory in our solar system - has been of much interest to the scientific community due to recent flybys of the spacecraft MESSENGER that discovered its intrinsic stationary and large-scale dipole like magnetic field structure with an intensity of ˜300nT confirming Mariner 10 observations. In the present study, with the observed constraint of Mercury's atmospheric magnetic field structure, internal magnetic field structure is modeled as a solution of magnetic diffusion equation. In this study, Mercury's internal structure mainly consists of a stable stratified fluid core and the convective mantle. For simplicity, magnetic diffusivity in both parts of the structure is considered to be uniform and constant with a value represented by a suitable averages. It is further assumed that vigorous convection in the mantle disposes of the electric currents leading to a very high diffusivity in that region. Thus, in order to satisfy observed atmospheric magnetic field structure, Mercury's most likely magnetic field structure consists of a solution of MHD diffusion equation in the core and a combined multipolar (dipole and quadrupole like magnetic field structures embedded in the uniform field) solution of a current free like magnetic field structure in the mantle and in the atmosphere. With imposition of appropriate boundary conditions at the core-mantle boundary for the first two diffusion eigen modes, in order to satisfy the observed field structure, present study puts the constraint on Mercury's core radius to be ˜2000km. From the estimated magnetic diffusivity and the core radius, it is also possible to estimate the two diffusion eigen modes with their diffusion time scales of ˜8.6 and 3.7 billion years respectively suggesting that the planet inherits its present-day magnetic field structure from the solar Nebula. It is proposed that permanency of such a large-scale magnetic field structure of the planet is attained during

  20. Structure development in magnetic paints

    SciTech Connect

    Potanin, A.A.; Shrauti, S.M.; Lane, A.M.; Arnold, D.W.

    1996-12-31

    Dynamic rheological measurements are used to probe the structure of model magnetic paints which contain ferro-magnetic particles of iron oxide or barium ferrite a wetting resin and a solvent. Along with industrially used organic solvent-based paints, water-borne systems are studied. Methods to characterize the dispersion quality of pigment particles through rheological measurements are outlined.

  1. Psychological characteristics of and counseling for carriers of structural chromosome abnormalities.

    PubMed

    Wang, H L; Wu, B; Guo, K M; Tian, R H

    2016-01-01

    Infertility as a psychological problem has gained increasing attention. Male partners among infertile couples have elevated levels of psychological distress, which could affect semen quality, result in hormonal abnormalities, and increase the occurrence of early miscarriage. Infertile women are more vulnerable to psychological distress and require psychological support. Subfertile women who conceive after assisted reproduction have higher stress, anxiety, and depression levels. Psychological interventions have been shown to have beneficial effects on infertility patients. However, psychosocial characteristics of carriers of structural chromosome abnormalities have not been studied. We report the characteristics of carriers of structural chromosome abnormalities and their influence on psychological counseling. Seventy-five patients were carriers of reciprocal translocations, 25 carried Robertsonian translocations, 17 carried inversions, 10 carried deletions, and 3 carried isochromosomes. The main clinical characteristics were recurrent spontaneous abortion, oligospermatism, azoospermatism, primary amenorrhea, and fetal death. Self-rating anxiety scale (SAS) and self-rating depression scale (SDS) scores of women with structural chromosome abnormality were significantly higher than those scores of women with normal karyotype. SAS and SDS scores of men with structural chromosome abnormality were significantly higher than those of men with normal karyotype. SAS and SDS scores of women with structural chromosome abnormality were significantly higher than their scores of men with structural chromosome abnormality. Women carriers with structural chromosome abnormality were more vulnerable to psychological distress. Psychosocial counseling for carriers of structural chromosome abnormalities should focus on self-confidence and treatment with assisted reproductive technology. PMID:27173267

  2. The course of neuropsychological impairment and brain structure abnormalities in psychotic disorders.

    PubMed

    Woodward, Neil D

    2016-01-01

    Neuropsychological impairment and abnormalities in brain structure are commonly observed in psychotic disorders, including schizophrenia and bipolar disorder. Shared deficits in neuropsychological functioning and abnormalities in brain structure suggest overlapping neuropathology between schizophrenia and bipolar disorder which has important implications for psychiatric nosology, treatment, and our understanding of the etiology of psychotic illnesses. However, the emergence and trajectory of brain dysfunction in psychotic disorders is less well understood. Differences in the course and progression of neuropsychological impairment and brain abnormalities among psychotic disorders may point to unique neuropathological processes. This article reviews the course of neuropsychological impairment and brain structure abnormalities in schizophrenia and bipolar disorder.

  3. Common and distinct structural network abnormalities in major depressive disorder and borderline personality disorder.

    PubMed

    Depping, Malte S; Wolf, Nadine D; Vasic, Nenad; Sambataro, Fabio; Thomann, Philipp A; Wolf, R Christian

    2016-02-01

    Major depressive disorder (MDD) and borderline personality disorder (BPD) show substantial overlap in both affective symptom expression and in regional brain volume reduction. To address the specificity of structural brain change for the respective diagnostic category, we investigated structural networks in MDD and BPD to identify shared and distinct patterns of abnormal brain volume associated with these phenotypically related disorders. Using magnetic resonance imaging at 3 T, we studied 22 females with MDD, 17 females with BPD and without comorbid posttraumatic stress disorder, and 22 age-matched female healthy controls. We used “source-based morphometry” (SBM) to investigate naturally grouping patterns of gray matter volume variation (i.e. “structural networks”) and the magnitude of their expression between groups. SBM identified three distinct structural networks which showed a significant group effect (p b 0.05, FDR-corrected). A bilateral frontostriatal network showed reduced volume in MDD compared to both controls and BPD patients. A medial temporal/medial frontal network was found to be significantly reduced in BPD compared to both controls and MDD patients. Decreased cingulate and lateral prefrontal volume was found in both MDD and BPD when compared to healthy individuals. In MDD significant relationships were found between depressive symptoms and a cingulate/lateral prefrontal structural pattern. In contrast, overall BPD symptoms and impulsivity scores were significantly associated with medial temporal/medial frontal network volume. The data suggest both distinct and common patterns of abnormal brain volume in MDD and BPD. Alterations of distinct structural networks differentially modulate clinical symptom expression in these disorders.

  4. Plated lamination structures for integrated magnetic devices

    DOEpatents

    Webb, Bucknell C.

    2014-06-17

    Semiconductor integrated magnetic devices such as inductors, transformers, etc., having laminated magnetic-insulator stack structures are provided, wherein the laminated magnetic-insulator stack structures are formed using electroplating techniques. For example, an integrated laminated magnetic device includes a multilayer stack structure having alternating magnetic and insulating layers formed on a substrate, wherein each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by an insulating layer, and a local shorting structure to electrically connect each magnetic layer in the multilayer stack structure to an underlying magnetic layer in the multilayer stack structure to facilitate electroplating of the magnetic layers using an underlying conductive layer (magnetic or seed layer) in the stack as an electrical cathode/anode for each electroplated magnetic layer in the stack structure.

  5. Structural and functional brain abnormalities place phenocopy frontotemporal dementia (FTD) in the FTD spectrum

    PubMed Central

    Steketee, Rebecca M.E.; Meijboom, Rozanna; Bron, Esther E.; Osse, Robert Jan; de Koning, Inge; Jiskoot, Lize C.; Klein, Stefan; de Jong, Frank Jan; van der Lugt, Aad; van Swieten, John C.; Smits, Marion

    2016-01-01

    Purpose ‘Phenocopy’ frontotemporal dementia (phFTD) patients may clinically mimic the behavioral variant of FTD (bvFTD), but do not show functional decline or abnormalities upon visual inspection of routine neuroimaging. We aimed to identify abnormalities in gray matter (GM) volume and perfusion in phFTD and to assess whether phFTD belongs to the FTD spectrum. We compared phFTD patients with both healthy controls and bvFTD patients. Materials & methods Seven phFTD and 11 bvFTD patients, and 20 age-matched controls underwent structural T1-weighted magnetic resonance imaging (MRI) and 3D pseudo-continuous arterial spin labeling (pCASL) at 3T. Normalized GM (nGM) volumes and perfusion, corrected for partial volume effects, were quantified regionally as well as in the entire supratentorial cortex, and compared between groups taking into account potential confounding effects of gender and scanner. Results PhFTD patients showed cortical atrophy, most prominently in the right temporal lobe. Apart from this regional atrophy, GM volume was generally not different from either controls or from bvFTD. BvFTD however showed extensive frontotemporal atrophy. Perfusion was increased in the left prefrontal cortex compared to bvFTD and to a lesser extent to controls. Conclusion PhFTD and bvFTD show overlapping cortical structural abnormalities indicating a continuum of changes especially in the frontotemporal regions. Together with functional changes suggestive of a compensatory response to incipient pathology in the left prefrontal regions, these findings are the first to support a possible neuropathological etiology of phFTD and suggest that phFTD may be a neurodegenerative disease on the FTD spectrum. PMID:27222795

  6. Structural abnormalities of muscle tissue in ankylosing spondylitis.

    PubMed

    Berman, L; Isaacs, H; Pickering, A

    1976-07-24

    Muscle tissue of patients with ankylosing spondylitis has been studied by means of histology, histochemistry and electron microscopy and has been shown to be grossly abnormal. The underlying basis of the muscle changes is probably neuropathic and we believe that these changes form part of the over-all pathology of this disease.

  7. Structural abnormalities of common carp Cyprinus carpio spermatozoa.

    PubMed

    Psenicka, Martin; Rodina, Marek; Flajshans, Martin; Kaspar, Vojtech; Linhart, Otomar

    2009-11-01

    Spermatozoa of common carp Cyprinus carpio are typically consist of a primitive head without acrosome, a midpiece with several mitochondria, a centriolar complex (proximal and distal centriole), and one flagellum. During an evaluation of the motility of common carp spermatozoa, we found spermatozoa with more than one flagellum and/or "double head" in three different individuals. This may be related to abnormal spermatogenesis. Ultrastructure and physiological parameters of spermatozoa were examined using light microscopy (dark field with stroboscopic illumination), transmission and scanning electron microscopy, and flow cytometry. The recorded pictures and videos were evaluated using Olympus MicroImage software. All spermatozoa with more than one flagellum had a larger head and shorter flagella. They occasionally demonstrated several cytoplasmic channels separating the flagella from the midpiece. Each flagellum was based upon its own centriolar complex, with the connection of the flagellum to the head always at a constant angle. The flagella always consisted of nine peripheral pairs and one central doublet of microtubules. Sperm exhibited a relative DNA content similar to that found in sperm from normal males, with higher coefficients of variation. Although similar abnormalities have been found in livestock, where they were described as a defect in spermiogenesis, no comparable results have been reported in fish. The frequency at which these abnormalities occurs, the fertilization ability of males with defects in spermiogenesis, the influence of these abnormalities on progeny in terms of ploidy level, and the occurrence of deformities warrant further investigation.

  8. Abnormal causal connectivity by structural deficits in first-episode, drug-naive schizophrenia at rest.

    PubMed

    Guo, Wenbin; Liu, Feng; Liu, Jianrong; Yu, Liuyu; Zhang, Jian; Zhang, Zhikun; Xiao, Changqing; Zhai, Jinguo; Zhao, Jingping

    2015-01-01

    Anatomical deficits and resting-state functional connectivity (FC) alterations in prefrontal-thalamic-cerebellar circuit have been implicated in the neurobiology of schizophrenia. However, the effect of structural deficits in schizophrenia on causal connectivity of this circuit remains unclear. This study was conducted to examine the causal connectivity biased by structural deficits in first-episode, drug-naive schizophrenia patients. Structural and resting-state functional magnetic resonance imaging (fMRI) data were obtained from 49 first-episode, drug-naive schizophrenia patients and 50 healthy controls. Data were analyzed by voxel-based morphometry and Granger causality analysis. The causal connectivity of the integrated prefrontal-thalamic (limbic)-cerebellar (sensorimotor) circuit was partly affected by structural deficits in first-episode, drug-naive schizophrenia as follows: (1) unilateral prefrontal-sensorimotor connectivity abnormalities (increased driving effect from the left medial prefrontal cortex [MPFC] to the sensorimotor regions); (2) bilateral limbic-sensorimotor connectivity abnormalities (increased driving effect from the right anterior cingulate cortex [ACC] to the sensorimotor regions and decreased feedback from the sensorimotor regions to the right ACC); and (3) bilateral increased and decreased causal connectivities among the sensorimotor regions. Some correlations between the gray matter volume of the seeds, along with their causal effects and clinical variables (duration of untreated psychosis and symptom severity), were also observed in the patients. The findings indicated the partial effects of structural deficits in first-episode, drug-naive schizophrenia on the prefrontal-thalamic (limbic)-cerebellar (sensorimotor) circuit. Schizophrenia may reinforce the driving connectivities from the left MPFC or right ACC to the sensorimotor regions and may disrupt bilateral causal connectivities among the sensorimotor regions.

  9. Polysubstance and Alcohol Dependence: Unique Abnormalities of Magnetic Resonance-Derived Brain Metabolite Levels

    PubMed Central

    Abé, Christoph; Mon, Anderson; Durazzo, Timothy C.; Pennington, David L.; Schmidt, Thomas P.; Meyerhoff, Dieter J.

    2012-01-01

    BACKGROUND Although comorbid substance misuse is common in alcohol dependence, and polysubstance abusers (PSU) represent the largest group of individuals seeking treatment for drug abuse today, we know little about potential brain abnormalities in this population. Brain magnetic resonance spectroscopy studies of mono-substance use disorders (e.g., alcohol or cocaine) reveal abnormal levels of cortical metabolites (reflecting neuronal integrity, cell membrane turnover/synthesis, cellular bioenergetics, gliosis) and altered concentrations of glutamate and γ-aminobutyric acid (GABA). The concurrent misuse of several substances may have unique and different effects on brain biology and function compared to any mono-substance misuse. METHODS High field brain magnetic resonance spectroscopy at 4 Tesla and neurocognitive testing were performed at one month of abstinence in 40 alcohol dependent individuals (ALC), 28 alcohol dependent PSU and 16 drug-free controls. Absolute metabolite concentrations were calculated in anterior cingulate (ACC), parieto-occipital (POC) and dorsolateral prefrontal cortices (DLPFC). RESULTS Compared to ALC, PSU demonstrated significant metabolic abnormalities in the DLPFC and strong trends to lower GABA in the ACC. Metabolite levels in ALC and light drinking controls were statistically equivalent. Within PSU, lower DLPFC GABA levels related to greater cocaine consumption. Several cortical metabolite concentrations were associated with cognitive performance. CONCLUSIONS While metabolite concentrations in ALC at one month of abstinence were largely normal, PSU showed persistent and functionally significant metabolic abnormalities, primarily in the DLPFC. Our results point to specific metabolic deficits as biomarkers in polysubstance misuse and as targets for pharmacological and behavioral PSU-specific treatment. PMID:23122599

  10. Transcranial magnetic stimulation studies in the Miller Fisher syndrome: evidence of corticospinal tract abnormality

    PubMed Central

    Lo, Y; Ratnagopal, P

    2001-01-01

    OBJECTIVES—To evaluate serial central motor conduction time in the Miller Fisher syndrome.
METHOD—Three patients with classic Miller Fisher syndrome were evaluated clinically. They had serial central motor conduction times measured with transcranial magnetic stimulation and nerve conduction studies. Motor evoked potentials were recorded from the first dorsal interossei and abductor hallucis muscles.
RESULTS—All three patients showed reduction in central motor conduction times in tandem with gradual clinical improvement at each review.
CONCLUSIONS—There is electrophysiological evidence of a central reversible corticospinal tract conduction abnormality in the Miller Fisher syndrome.

 PMID:11459894

  11. Electrocardiographic abnormalities and cardiac arrhythmias in structural brain lesions.

    PubMed

    Katsanos, Aristeidis H; Korantzopoulos, Panagiotis; Tsivgoulis, Georgios; Kyritsis, Athanassios P; Kosmidou, Maria; Giannopoulos, Sotirios

    2013-07-31

    Cardiac arrhythmias and electrocardiographic abnormalities are frequently observed after acute cerebrovascular events. The precise mechanism that leads to the development of these arrhythmias is still uncertain, though increasing evidence suggests that it is mainly due to autonomic nervous system dysregulation. In massive brain lesions sympathetic predominance and parasympathetic withdrawal during the first 72 h are associated with the occurrence of severe secondary complications in the first week. Right insular cortex lesions are also related with sympathetic overactivation and with a higher incidence of electrocardiographic abnormalities, mostly QT prolongation, in patients with ischemic stroke. Additionally, female sex and hypokalemia are independent risk factors for severe prolongation of the QT interval which subsequently results in malignant arrhythmias and poor outcome. The prognostic value of repolarization changes commonly seen after aneurysmal subarachnoid hemorrhage, such as ST segment, T wave, and U wave abnormalities, still remains controversial. In patients with traumatic brain injury both intracranial hypertension and cerebral hypoperfusion correlate with low heart rate variability and increased mortality. Given that there are no firm guidelines for the prevention or treatment of the arrhythmias that appear after cerebral incidents this review aims to highlight important issues on this topic. Selected patients with the aforementioned risk factors could benefit from electrocardiographic monitoring, reassessment of the medications that prolong QTc interval, and administration of antiadrenergic agents. Further research is required in order to validate these assumptions and to establish specific therapeutic strategies.

  12. A functional Magnetic Resonance Imaging study of neurohemodynamic abnormalities during emotion processing in subjects at high risk for schizophrenia

    PubMed Central

    Venkatasubramanian, Ganesan; Puthumana, Dawn Thomas K.; Jayakumar, Peruvumba N.; Gangadhar, B. N.

    2010-01-01

    Background: Emotion processing abnormalities are considered among the core deficits in schizophrenia. Subjects at high risk (HR) for schizophrenia also show these deficits. Structural neuroimaging studies examining unaffected relatives at high risk for schizophrenia have demonstrated neuroanatomical abnormalities involving neo-cortical and sub-cortical brain regions related to emotion processing. The brain functional correlates of emotion processing in these HR subjects in the context of ecologically valid, real-life dynamic images using functional Magnetic Resonance Imaging (fMRI) has not been examined previously. Aim: To examine the neurohemodynamic abnormalities during emotion processing in unaffected subjects at high risk for schizophrenia in comparison with age-, sex-, handedness- and education-matched healthy controls, using fMRI. Materials and Methods: HR subjects for schizophrenia (n=17) and matched healthy controls (n=16) were examined. The emotion processing of fearful facial expression was examined using a culturally appropriate and valid tool for Indian subjects. The fMRI was performed in a 1.5-T scanner during an implicit emotion processing paradigm. The fMRI analyses were performed using the Statistical Parametric Mapping 2 (SPM2) software. Results: HR subjects had significantly reduced brain activations in left insula, left medial frontal gyrus, left inferior frontal gyrus, right cingulate gyrus, right precentral gyrus and right inferior parietal lobule. Hypothesis-driven region-of-interest analysis revealed hypoactivation of right amygdala in HR subjects. Conclusions: Study findings suggest that neurohemodynamic abnormalities involving limbic and frontal cortices could be potential indicators for increased vulnerability toward schizophrenia. The clinical utility of these novel findings in predicting the development of psychosis needs to be evaluated. PMID:21267363

  13. Abnormal Magnetic Resonance Imaging Findings in Patients With Sudden Sensorineural Hearing Loss

    PubMed Central

    Jeong, Kyung-Hwa; Choi, Jin Woo; Shin, Jung Eun; Kim, Chang-Hee

    2016-01-01

    Abstract The etiology of sudden sensorineural hearing loss (SSNHL) remains unclear in most cases. This study aimed to assess abnormal magnetic resonance imaging (MRI) findings in patients with SSNHL and evaluate the value of MRI in identifying the cause of SSNHL. A retrospective analysis of the charts and MRI findings of 291 patients with SSNHL was performed. In 291 patients, MRI abnormality, which was considered a cause of SSNHL, was detected in 13 patients. Vestibular schwannoma involving the internal auditory canal (IAC) and/or cerebellopontine angle was observed in 9 patients. All 9 patients had intrameatal tumors, and 6 of the 9 patients displayed extrameatal extension of their tumors. The tumor was small (<1 cm) or medium-sized (1.1–2.9 cm) in these 6 patients. Intralabyrinthine schwannoma, labyrinthine hemorrhage, IAC metastasis, and a ruptured dermoid cyst were each observed in 1 patient. The most commonly observed MRI abnormality in patients with SSNHL was vestibular schwannoma, and all of the lesions were small or medium-sized tumors involving the IAC. PMID:27124066

  14. Magnetization transfer ratio measures in normal-appearing white matter show periventricular gradient abnormalities in multiple sclerosis.

    PubMed

    Liu, Zheng; Pardini, Matteo; Yaldizli, Özgür; Sethi, Varun; Muhlert, Nils; Wheeler-Kingshott, Claudia A M; Samson, Rebecca S; Miller, David H; Chard, Declan T

    2015-05-01

    bands was significantly lower in patients with multiple sclerosis. In controls, magnetization transfer ratio was highest in the band adjacent to the ventricles and declined with increasing distance from the ventricles. In the multiple sclerosis groups, relative to controls, reductions in magnetization transfer ratio were greater in the secondary progressive multiple sclerosis compared with relapsing remitting multiple sclerosis group, and these reductions were greatest next to the ventricles and became smaller with distance from them. White matter lesion magnetization transfer ratio reductions were also more apparent adjacent to the ventricle and decreased with distance from the ventricles in both the relapsing remitting and secondary progressive multiple sclerosis groups. These findings suggest that in people with multiple sclerosis, and more so in secondary progressive than relapsing remitting multiple sclerosis, tissue structural abnormalities in normal-appearing white matter and white matter lesions are greatest near the ventricles. This would be consistent with a cerebrospinal fluid or ependymal mediated pathogenesis.

  15. Molecular cytogenetic studies in structural abnormalities of chromosome 13

    SciTech Connect

    Lozzio, C.B.; Bamberger, E.; Anderson, I.

    1994-09-01

    A partial trisomy 13 was detected prenatally in an amniocentesis performed due to the following ultrasound abnormalities: open sacral neural tube defect (NTD), a flattened cerebellum, and lumbar/thoracic hemivertebrae. Elevated AFP and positive acetylcholinesterase in amniotic fluid confirmed the open NTD. Chromosome analysis showed an extra acrocentric chromosome marker. FISH analysis with the painting probe 13 showed that most of the marker was derived from this chromosome. Chromosomes on the parents revealed that the mother had a balanced reciprocal translocation t(2;13)(q23;q21). Dual labeling with painting chromosomes 2 and 13 on cells from the mother and from the amniotic fluid identified the marker as a der(13)t(2;13)(p23;q21). Thus, the fetus had a partial trisomy 13 and a small partial trisomy 2p. The maternal grandfather was found to be a carrier for this translocation. Fetal demise occurred a 29 weeks of gestation. The fetus had open lumbar NTD and showed dysmorphic features, overlapping fingers and imperforate anus. This woman had a subsequent pregnancy and chorionic villi sample showed that this fetus was normal. Another case with an abnormal chromosome 13 was a newborn with partial monosomy 13 due to the presence of a ring chromosome 13. This infant had severe intrauterine growth retardation, oligohydramnios, dysmorphic features and multiple congenital microphthalmia, congenital heart disease, absent thumbs and toes and cervical vertebral anomalies. Chromosome studies in blood and skin fibroblast cultures showed that one chromosome 3 was replaced by a ring chromosome of various sizes. This ring was confirmed to be derived from chromosome 13 using the centromeric 21/13 probe.

  16. Magnetized Accretion-Ejection Structures

    NASA Astrophysics Data System (ADS)

    Ferreira, Jonathan

    1994-09-01

    balance between the differential rotation effect (that tends to provide a negative radial current inside the disk) and the "Barlow Wheel" effect (that gives rise to a positive radial current at the disk midplane, hence allowing magnetic braking), leading to the decrease on a disk scale height of the radial current. This means that the field lines are less sheared as one goes upwards to the disk surface. A natural transition between the accretion disk and the jet arises because, as the radial current decreases vertically, the vertical magnetic compression drops and the plasma pressure gradient gives rise to an ascendant motion. Thus, it is the plasma pressure that first drives ejection. The magnetic tension forces then the plasma to be ejected outwardly, being then more and more attached to the poloidal field lines. In the ideal MHD region above the disk, the jet velocity becomes super slow-magnetosonic (first critical point encountered by the flow) and increases due to both magnetic and centrifugal forces. The overall structure is complex, with an equipartition between magnetic and thermal energy densities as well as components of the magnetic field of the same order of magnitude at the disk surface. The full parameter space of such a structure will be fixed by two additional regularity conditions, at the Alfvénic and fast magnetosonic critical points of the jet. We derive, for both AGN and YSO, the observational signatures of optically thick MHD disks driving jets, as well as the global energy budget and its consequences on jets.

  17. Abnormal fb Es enhancements in equatorial Es layers during magnetic storms of solar cycle 23

    NASA Astrophysics Data System (ADS)

    Resende, L. C. A.; Denardini, C. M.; Batista, I. S.

    2013-09-01

    We have analyzed the behavior of blanketing frequency of the Es layer (fb Es) occurring at an equatorial station covering the days before, during and subsequent to 24 intense and very intense magnetic storms (Dst≤-100 nT) that occurred during the solar cycle 23. The fb Es was measured by digital ionosonde over São Luís, Brazil (2.33° S, 44.2° W, dip: -4.5°). Our analysis shows that there are significant changes in the fb Es, mainly during the recovery phase of magnetic storms, characterized by occurrence of peaks that exceed the ambient background values. Also, these peaks are associated to other types of sporadic E layer than the Esq (a non-blanketing layer detected due the plasma irregularities in the equatorial electrojet), which in turn means competing mechanisms. The results are discussed in terms of the statistics of the abnormal enhancement taking into account the phase of the magnetic storm.

  18. The Measuring and Protection Method for the Abnormal Rise of Magnetizing Inrush Current in a Divided Type 3 CTs System

    NASA Astrophysics Data System (ADS)

    Iwasaki, Fumio; Ibe, Masayuki; Ninohei, Koichiro; Okamura, Seichiro

    This paper describes the measuring and protection method for the abnormal rise of magnetizing inrush current in a divided type 3 CTs system. By divided type 3 CTs system, it is possible to measure the primary phase current and zero phase current at the same time. In this reason, the divided type 3 CTs system is widely used for the measurement of high voltage distribution line by simply clamping the each phase lines with 3CTs. For the accurate measurement of the phase current and zero phase current, the internal residual current in CT should be small as possible. It is reported that the abnormal rise of the residual current is generated in the practical field use and several ten ampere (converted to the primary current value) is observed in some case. The abnormal rise of the residual current is caused by the primary magnetizing inrush current or by the sum of the influence by electromagnetic field of the nearby conductors. The magnetizing inrush current is caused by the magnetic saturation of the core of CT. It is difficult to eliminate the abnormal residual current by using the bigger size of core. In our test, we used the active elements and independent feed back coils around the right and left core of CT. By using the feed back current from these coils it was observed that the magnetic saturation of the core is improved and the magnetizing inrush current can be controlled.

  19. Modeling the thermal and structural response of engineered systems to abnormal environments

    SciTech Connect

    Skocypec, R.D.; Thomas, R.K.; Moya, J.L.

    1993-10-01

    Sandia National Laboratories (SNL) is engaged actively in research to improve the ability to accurately predict the response of engineered systems to thermal and structural abnormal environments. Abnormal environments that will be addressed in this paper include: fire, impact, and puncture by probes and fragments, as well as a combination of all of the above. Historically, SNL has demonstrated the survivability of engineered systems to abnormal environments using a balanced approach between numerical simulation and testing. It is necessary to determine the response of engineered systems in two cases: (1) to satisfy regulatory specifications, and (2) to enable quantification of a probabilistic risk assessment (PRA). In a regulatory case, numerical simulation of system response is generally used to guide the system design such that the system will respond satisfactorily to the specified regulatory abnormal environment. Testing is conducted at the regulatory abnormal environment to ensure compliance.

  20. Age at First Episode Modulates Diagnosis-Related Structural Brain Abnormalities in Psychosis.

    PubMed

    Pina-Camacho, Laura; Del Rey-Mejías, Ángel; Janssen, Joost; Bioque, Miquel; González-Pinto, Ana; Arango, Celso; Lobo, Antonio; Sarró, Salvador; Desco, Manuel; Sanjuan, Julio; Lacalle-Aurioles, Maria; Cuesta, Manuel J; Saiz-Ruiz, Jerónimo; Bernardo, Miguel; Parellada, Mara

    2016-03-01

    Brain volume and thickness abnormalities have been reported in first-episode psychosis (FEP). However, it is unclear if and how they are modulated by brain developmental stage (and, therefore, by age at FEP as a proxy). This is a multicenter cross-sectional case-control brain magnetic resonance imaging (MRI) study. Patients with FEP (n = 196), 65.3% males, with a wide age at FEP span (12-35 y), and healthy controls (HC) (n = 157), matched for age, sex, and handedness, were scanned at 6 sites. Gray matter volume and thickness measurements were generated for several brain regions using FreeSurfer software. The nonlinear relationship between age at scan (a proxy for age at FEP in patients) and volume and thickness measurements was explored in patients with schizophrenia spectrum disorders (SSD), affective psychoses (AFP), and HC. Earlier SSD cases (ie, FEP before 15-20 y) showed significant volume and thickness deficits in frontal lobe, volume deficits in temporal lobe, and volume enlargements in ventricular system and basal ganglia. First-episode AFP patients had smaller cingulate cortex volume and thicker temporal cortex only at early age at FEP (before 18-20 y). The AFP group also had age-constant (12-35-y age span) volume enlargements in the frontal and parietal lobe. Our study suggests that age at first episode modulates the structural brain abnormalities found in FEP patients in a nonlinear and diagnosis-dependent manner. Future MRI studies should take these results into account when interpreting samples with different ages at onset and diagnosis. PMID:26371339

  1. Age at First Episode Modulates Diagnosis-Related Structural Brain Abnormalities in Psychosis.

    PubMed

    Pina-Camacho, Laura; Del Rey-Mejías, Ángel; Janssen, Joost; Bioque, Miquel; González-Pinto, Ana; Arango, Celso; Lobo, Antonio; Sarró, Salvador; Desco, Manuel; Sanjuan, Julio; Lacalle-Aurioles, Maria; Cuesta, Manuel J; Saiz-Ruiz, Jerónimo; Bernardo, Miguel; Parellada, Mara

    2016-03-01

    Brain volume and thickness abnormalities have been reported in first-episode psychosis (FEP). However, it is unclear if and how they are modulated by brain developmental stage (and, therefore, by age at FEP as a proxy). This is a multicenter cross-sectional case-control brain magnetic resonance imaging (MRI) study. Patients with FEP (n = 196), 65.3% males, with a wide age at FEP span (12-35 y), and healthy controls (HC) (n = 157), matched for age, sex, and handedness, were scanned at 6 sites. Gray matter volume and thickness measurements were generated for several brain regions using FreeSurfer software. The nonlinear relationship between age at scan (a proxy for age at FEP in patients) and volume and thickness measurements was explored in patients with schizophrenia spectrum disorders (SSD), affective psychoses (AFP), and HC. Earlier SSD cases (ie, FEP before 15-20 y) showed significant volume and thickness deficits in frontal lobe, volume deficits in temporal lobe, and volume enlargements in ventricular system and basal ganglia. First-episode AFP patients had smaller cingulate cortex volume and thicker temporal cortex only at early age at FEP (before 18-20 y). The AFP group also had age-constant (12-35-y age span) volume enlargements in the frontal and parietal lobe. Our study suggests that age at first episode modulates the structural brain abnormalities found in FEP patients in a nonlinear and diagnosis-dependent manner. Future MRI studies should take these results into account when interpreting samples with different ages at onset and diagnosis.

  2. Metabolic differentiation and classification of abnormal Savda Munziq's pharmacodynamic role on rat models with different diseases by nuclear magnetic resonance-based metabonomics

    PubMed Central

    Mamtimin, Batur; Xia, Guo; Mijit, Mahmut; Hizbulla, Mawlanjan; Kurbantay, Nazuk; You, Li; Upur, Halmurat

    2015-01-01

    Background: Abnormal Savda Munziq (ASMq) is a traditional Uyghur herbal preparation used as a therapy for abnormal Savda-related diseases. In this study, we investigate ASMq's dynamic effects on abnormal Savda rat models under different disease conditions. Materials and Methods: Abnormal Savda rat models with hepatocellular carcinoma (HCC), type 2 diabetes mellitus (T2DM), and asthma dosed of ASMq. Serum samples of each animal tested by nuclear magnetic resonance spectroscopy and analyzed by orthogonal projection to latent structure with discriminant analysis. Results: Compared with healthy controls, HCC rats had higher concentrations of amino acids, fat-related metabolites, lactate, myoinositol, and citrate, but lower concentrations of α-glucose, β-glucose, and glutamine. Following ASMq treatment, the serum acetone very low-density lipoprotein (VLDL), LDL, unsaturated lipids, acetylcysteine, and pyruvate concentration decreased, but α-glucose, β-glucose, and glutamine concentration increased (P < 0.05). T2DM rats had higher concentrations of α- and β-glucose, but lower concentrations of isoleucine, leucine, valine, glutamine, glycoprotein, lactate, tyrosine, creatine, alanine, carnitine, and phenylalanine. After ASMq treated T2DM groups showed reduced α- and β-glucose and increased creatine levels (P < 0.05). Asthma rats had higher acetate, carnitine, formate, and phenylalanine levels, but lower concentrations of glutamine, glycoprotein, lactate, VLDL, LDL, and unsaturated lipids. ASMq treatment showed increased glutamine and reduced carnitine, glycoprotein, formate, and phenylalanine levels (P < 0.05). Conclusion: Low immune function, decreased oxidative defense, liver function abnormalities, amino acid deficiencies, and energy metabolism disorders are common characteristics of abnormal Savda-related diseases. ASMq may improve the abnormal metabolism and immune function of rat models with different diseases combined abnormal Savda. PMID:26600713

  3. Structural abnormalities of small resistance arteries in essential hypertension.

    PubMed

    Rizzoni, Damiano; Agabiti-Rosei, Enrico

    2012-06-01

    Regardless of the mechanisms that initiate the increase in blood pressure, the development of structural changes in the systemic vasculature is the end result of established hypertension. In essential hypertension, the small arteries smooth muscle cells are restructured around a smaller lumen, and there is no net growth of the vascular wall, while in some secondary forms of hypertension, a hypertrophic remodeling may be detected. Also, in non-insulin-dependent diabetes mellitus, a hypertrophic remodeling of subcutaneous small arteries is present. The results from our own group have suggested that indices of small resistance artery structure, such as the tunica media to internal lumen ratio, may have a strong prognostic significance in hypertensive patients, over and above all other known cardiovascular risk factors. Therefore, the regression of vascular alterations is an appealing goal of antihypertensive treatment. Different antihypertensive drugs seem to have different effect on vascular structure, both in human and in animal models of genetic and experimental hypertension. A complete normalization of small resistance artery structure is demonstrated in hypertensive patients, after long-term and effective therapy with ACE inhibitors, angiotensin II receptor blockers and calcium antagonists. Few data are available in diabetic hypertensive patients; however, blockade of the renin-angiotensin system seems to be effective in this regard. In conclusion, there are several pieces of evidence that suggest that small resistance artery structure may be considered an intermediate endpoint in the evaluation of the effects of antihypertensive therapy; however, there are presently no data available about the prognostic impact of the regression of vascular structural alterations in hypertension and diabetes.

  4. Delineating the Structure of Normal and Abnormal Personality: An Integrative Hierarchical Approach

    PubMed Central

    Markon, Kristian E.; Krueger, Robert F.; Watson, David

    2008-01-01

    Increasing evidence indicates that normal and abnormal personality can be treated within a single structural framework. However, identification of a single integrated structure of normal and abnormal personality has remained elusive. Here, a constructive replication approach was used to delineate an integrative hierarchical account of the structure of normal and abnormal personality. This hierarchical structure, which integrates many Big Trait models proposed in the literature, replicated across a meta-analysis as well as an empirical study, and across samples of participants as well as measures. The proposed structure resembles previously suggested accounts of personality hierarchy and provides insight into the nature of personality hierarchy more generally. Potential directions for future research on personality and psychopathology are discussed. PMID:15631580

  5. Brain Structure Abnormalities in Adolescent Girls with Conduct Disorder

    ERIC Educational Resources Information Center

    Fairchild, Graeme; Hagan, Cindy C.; Walsh, Nicholas D.; Passamonti, Luca; Calder, Andrew J.; Goodyer, Ian M.

    2013-01-01

    Background: Conduct disorder (CD) in female adolescents is associated with a range of negative outcomes, including teenage pregnancy and antisocial personality disorder. Although recent studies have documented changes in brain structure and function in male adolescents with CD, there have been no neuroimaging studies of female adolescents with CD.…

  6. HFE gene: Structure, function, mutations, and associated iron abnormalities.

    PubMed

    Barton, James C; Edwards, Corwin Q; Acton, Ronald T

    2015-12-15

    The hemochromatosis gene HFE was discovered in 1996, more than a century after clinical and pathologic manifestations of hemochromatosis were reported. Linked to the major histocompatibility complex (MHC) on chromosome 6p, HFE encodes the MHC class I-like protein HFE that binds beta-2 microglobulin. HFE influences iron absorption by modulating the expression of hepcidin, the main controller of iron metabolism. Common HFE mutations account for ~90% of hemochromatosis phenotypes in whites of western European descent. We review HFE mapping and cloning, structure, promoters and controllers, and coding region mutations, HFE protein structure, cell and tissue expression and function, mouse Hfe knockouts and knockins, and HFE mutations in other mammals with iron overload. We describe the pertinence of HFE and HFE to mechanisms of iron homeostasis, the origin and fixation of HFE polymorphisms in European and other populations, and the genetic and biochemical basis of HFE hemochromatosis and iron overload.

  7. Abnormal thermal expansion, multiple transitions, magnetocaloric effect, and electronic structure of Gd6Co4.85

    NASA Astrophysics Data System (ADS)

    Zhang, Jiliang; Zheng, Zhigang; Shan, Guangcun; Bobev, Svilen; Shek, Chan Hung

    2015-10-01

    The structure of known Gd4Co3 compound is re-determined as Gd6Co4.85, adopting the Gd6Co1.67Si3 structure type, which is characterized by two disorder Co sites filling the Gd octahedral and a short Gd-Gd distance within the octahedra. The compound shows uniaxial negative thermal expansion in paramagnetic state, significant negative expansion in ferromagnetic state, and positive expansion below ca. 140 K. It also exhibits large magnetocaloric effect, with an entropy change of -6.4 J kg-1 K-1 at 50 kOe. In the lattice of the compound, Co atoms at different sites show different spin states. It was confirmed by the X-ray photoelectron spectra and calculation of electronic structure and shed lights on the abnormal thermal expansion. The stability of such compound and the origin of its magnetism are also discussed based on measured and calculated electronic structures.

  8. Developmental abnormality induced by strong static magnetic field in Caenorhabditis elegans.

    PubMed

    Wang, Lei; Du, Hua; Guo, Xiaoying; Wang, Xinan; Wang, Meimei; Wang, Yichen; Wang, Min; Chen, Shaopeng; Wu, Lijun; Xu, An

    2015-04-01

    Understanding the effects of strong static magnetic fields (SMFs) on living organisms is significant in health risk assessment, but underlying mechanisms are largely unknown. In the present study, we determined developmental abnormalities induced by 8.5Tesla (T) SMFs in a well-established in vivo model organism, Caenorhabditis elegans (C. elegans). Exposure of C. elegans eggs to 8.5 T SMF resulted in a time-dependent lifespan decrease, whereas only slight changes were observed upon exposure to 5 T SMF. Although SMF exposure did not alter brood size, development rate and stages were significantly modified by 8.5 T SMF. Germ cell apoptosis dramatically increased upon exposure to 8.5 T SMF in adult worms, as confirmed by ced-3 and ced-4 mutants, and could be prevented by concurrent treatment with a free radical scavenger, dimethyl sulfoxide. Compared to wild-type worms, shorter lifespan and greater numbers of apoptotic cells were observed in abnormal methyl viologen sensitivity-1 (mev-1(kn1)) nematodes with increased sensitivity to oxidative damage. Furthermore, exposure to 8.5 T SMF increased expression of superoxide dismutase-3 (sod-3), which is thought to protect against oxidative stress. However, 8.5 T SMF had minimal effects on lifespans of daf-2 and daf-16 mutants, which have compromised insulin/IGF-1 (insulin-like growth factors-1) mediated signaling pathways; this finding was consistent with the expression of these genes in wild-type worms. Our results indicate that developmental toxicity induced by strong SMF in C. elegans is mediated by oxidative stress and may be regulated by the insulin-like receptor pathway.

  9. Abnormal brain structure in youth who commit homicide

    PubMed Central

    Cope, L.M.; Ermer, E.; Gaudet, L.M.; Steele, V.R.; Eckhardt, A.L.; Arbabshirani, M.R.; Caldwell, M.F.; Calhoun, V.D.; Kiehl, K.A.

    2014-01-01

    Background Violence that leads to homicide results in an extreme financial and emotional burden on society. Juveniles who commit homicide are often tried in adult court and typically spend the majority of their lives in prison. Despite the enormous costs associated with homicidal behavior, there have been no serious neuroscientific studies examining youth who commit homicide. Methods Here we use neuroimaging and voxel-based morphometry to examine brain gray matter in incarcerated male adolescents who committed homicide (n = 20) compared with incarcerated offenders who did not commit homicide (n = 135). Two additional control groups were used to understand further the nature of gray matter differences: incarcerated offenders who did not commit homicide matched on important demographic and psychometric variables (n = 20) and healthy participants from the community (n = 21). Results Compared with incarcerated adolescents who did not commit homicide (n = 135), incarcerated homicide offenders had reduced gray matter volumes in the medial and lateral temporal lobes, including the hippocampus and posterior insula. Feature selection and support vector machine learning classified offenders into the homicide and non-homicide groups with 81% overall accuracy. Conclusions Our results indicate that brain structural differences may help identify those at the highest risk for committing serious violent offenses. PMID:24936430

  10. [Microscopic anatomy of abnormal structure in root tuber of Pueraria lobata].

    PubMed

    Duan, Hai-yan; Cheng, Ming-en; Peng, Hua-sheng; Zhang, He-ting; Zhao, Yu-jiao

    2015-11-01

    Puerariae Lobatae Radix, also known as Gegen, is a root derived from Pueraria lobata. Based on field investigation and the developmental anatomy of root tuber, we have elucidated the relationship between the growth of root tuber and the anomalous structure. The results of analysis showed that the root system of P. lobata was developed from seed and adventitious root and there existed root tuber, adventitious root and conductive root according to morphology and function. The root tuber was developed from adventitious root, its secondary structure conformed to the secondary structure of dicotyledon's root. With the development of root, the secondary phloem of root tuber appeared abnormal vascular tissue, which was distributed like ring in the outside of secondary vascular tissue. The root tuber might have 4-6 concentric circular permutation abnormal vascular tissuelobate, and was formed by the internal development of abnormal vascular tissue. The xylem and phloem of abnormal vascular tissue were the main body of the root tuber. The results reveal the abnormal anatomical structure development of P. lobata, also provides the theoretical basis for reasonable harvest medicinal parts and promoting sustainable utilization of resources of P. lobata.

  11. [Microscopic anatomy of abnormal structure in root tuber of Pueraria lobata].

    PubMed

    Duan, Hai-yan; Cheng, Ming-en; Peng, Hua-sheng; Zhang, He-ting; Zhao, Yu-jiao

    2015-11-01

    Puerariae Lobatae Radix, also known as Gegen, is a root derived from Pueraria lobata. Based on field investigation and the developmental anatomy of root tuber, we have elucidated the relationship between the growth of root tuber and the anomalous structure. The results of analysis showed that the root system of P. lobata was developed from seed and adventitious root and there existed root tuber, adventitious root and conductive root according to morphology and function. The root tuber was developed from adventitious root, its secondary structure conformed to the secondary structure of dicotyledon's root. With the development of root, the secondary phloem of root tuber appeared abnormal vascular tissue, which was distributed like ring in the outside of secondary vascular tissue. The root tuber might have 4-6 concentric circular permutation abnormal vascular tissuelobate, and was formed by the internal development of abnormal vascular tissue. The xylem and phloem of abnormal vascular tissue were the main body of the root tuber. The results reveal the abnormal anatomical structure development of P. lobata, also provides the theoretical basis for reasonable harvest medicinal parts and promoting sustainable utilization of resources of P. lobata. PMID:27097408

  12. Structural Chromosome Abnormalities Associated with Obesity: Report of Four New subjects and Review of Literature.

    PubMed

    Dasouki, Majed J; Youngs, Erin L; Hovanes, Karine

    2011-05-01

    Obesity in humans is a complex polygenic trait with high inter-individual heritability estimated at 40-70%. Candidate gene, DNA linkage and genome-wide association studies (GWAS) have allowed for the identification of a large set of genes and genomic regions associated with obesity. Structural chromosome abnormalities usually result in congenital anomalies, growth retardation and developmental delay. Occasionally, they are associated with hyperphagia and obesity rather than growth delay. We report four new individuals with structural chromosome abnormalities involving 10q22.3-23.2, 16p11.2 and Xq27.1-q28 chromosomal regions with early childhood obesity and developmental delay. We also searched and summarized the literature for structural chromosome abnormalities reported in association with childhood obesity. PMID:22043167

  13. Structural Chromosome Abnormalities Associated with Obesity: Report of Four New subjects and Review of Literature

    PubMed Central

    Dasouki, Majed J; Youngs, Erin L; Hovanes, Karine

    2011-01-01

    Obesity in humans is a complex polygenic trait with high inter-individual heritability estimated at 40–70%. Candidate gene, DNA linkage and genome-wide association studies (GWAS) have allowed for the identification of a large set of genes and genomic regions associated with obesity. Structural chromosome abnormalities usually result in congenital anomalies, growth retardation and developmental delay. Occasionally, they are associated with hyperphagia and obesity rather than growth delay. We report four new individuals with structural chromosome abnormalities involving 10q22.3-23.2, 16p11.2 and Xq27.1-q28 chromosomal regions with early childhood obesity and developmental delay. We also searched and summarized the literature for structural chromosome abnormalities reported in association with childhood obesity. PMID:22043167

  14. Midline abnormalities and psychopathology: how reliable is the midsagittal magnetic resonance "window" into the brain?

    PubMed

    Coppola, R; Myslobodsky, M; Weinberger, D R

    1995-05-31

    The argument is made that mensuration of midsagittal magnetic resonance (MR) images is plagued with methodological errors due to confusion of the midsagittal MR image and the mesial brain surface. Several examples are given to demonstrate the effects of slice thickness and orientation on the size and shape of mesial structures. The benefits of examining contiguous slices and the necessity of consulting coronal and transaxial cuts in mensuration efforts of midsagittal cuts are emphasized.

  15. Gray matter textural heterogeneity as a potential in-vivo biomarker of fine structural abnormalities in Asperger syndrome.

    PubMed

    Radulescu, E; Ganeshan, B; Minati, L; Beacher, F D C C; Gray, M A; Chatwin, C; Young, R C D; Harrison, N A; Critchley, H D

    2013-02-01

    Brain imaging studies contribute to the neurobiological understanding of Autism Spectrum Conditions (ASC). Herein, we tested the prediction that distributed neurodevelopmental abnormalities in brain development impact on the homogeneity of brain tissue measured using texture analysis (TA; a morphological method for surface pattern characterization). TA was applied to structural magnetic resonance brain scans of 54 adult participants (24 with Asperger syndrome (AS) and 30 controls). Measures of mean gray-level intensity, entropy and uniformity were extracted from gray matter images at fine, medium and coarse textures. Comparisons between AS and controls identified higher entropy and lower uniformity across textures in the AS group. Data reduction of texture parameters revealed three orthogonal principal components. These were used as regressors-of-interest in a voxel-based morphometry analysis that explored the relationship between surface texture variations and regional gray matter volume. Across the AS but not control group, measures of entropy and uniformity were related to the volume of the caudate nuclei, whereas mean gray-level was related to the size of the cerebellar vermis. Similar to neuropathological studies, our study provides evidence for distributed abnormalities in the structural integrity of gray matter in adults with ASC, in particular within corticostriatal and corticocerebellar networks. Additionally, this in-vivo technique may be more sensitive to fine microstructural organization than other more traditional magnetic resonance approaches and serves as a future testable biomarker in AS and other neurodevelopmental disorders.

  16. Metabolic Abnormalities in Lobar and Subcortical Brain Regions of Abstinent Polysubstance Users: Magnetic Resonance Spectroscopic Imaging

    PubMed Central

    Abé, Christoph; Mon, Anderson; Hoefer, Michael E.; Durazzo, Timothy C.; Pennington, David L.; Schmidt, Thomas P.; Meyerhoff, Dieter J.

    2013-01-01

    Aims: The aim of the study was to explore neurometabolic and associated cognitive characteristics of patients with polysubstance use (PSU) in comparison with patients with predominant alcohol use using proton magnetic resonance spectroscopy. Methods: Brain metabolite concentrations were examined in lobar and subcortical brain regions of three age-matched groups: 1-month-abstinent alcohol-dependent PSU, 1-month-abstinent individuals dependent on alcohol alone (ALC) and light drinking controls (CON). Neuropsychological testing assessed cognitive function. Results: While CON and ALC had similar metabolite levels, persistent metabolic abnormalities (primarily higher myo-inositol) were present in temporal gray matter, cerebellar vermis and lenticular nuclei of PSU. Moreover, lower cortical gray matter concentration of the neuronal marker N-acetylaspartate within PSU correlated with higher cocaine (but not alcohol) use quantities and with a reduced cognitive processing speed. Conclusions: These metabolite group differences reflect cellular/astroglial injury and/or dysfunction in alcohol-dependent PSU. Associations of other metabolite concentrations with neurocognitive performance suggest their functional relevance. The metabolic alterations in PSU may represent polydrug abuse biomarkers and/or potential targets for pharmacological and behavioral PSU-specific treatment. PMID:23797281

  17. Reward Abnormalities Among Women with Full and Subthreshold Bulimia Nervosa: A Functional Magnetic Resonance Imaging Study

    PubMed Central

    Bohon, Cara; Stice, Eric

    2010-01-01

    Objective To test the hypothesis that women with full and subthreshold bulimia nervosa show abnormal neural activation in response to food intake and anticipated food intake relative to healthy control women. Method Females with and without full/subthreshold bulimia nervosa recruited from the community (N = 26) underwent functional magnetic resonance imaging (fMRI) during receipt and anticipated receipt of chocolate milkshake and a tasteless control solution. Results Women with bulimia nervosa showed trends for less activation than healthy controls in the right anterior insula in response to anticipated receipt of chocolate milkshake (versus tasteless solution) and in the left middle frontal gyrus, right posterior insula, right precentral gyrus, and right mid dorsal insula in response to consumptions of milkshake (versus tasteless solution). Discussion Bulimia nervosa may be related to potential hypo-functioning of the brain reward system, which may lead these individuals to binge eat to compensate for this reward deficit, though the hypo-responsivity might be a result of a history of binge eating highly palatable foods. PMID:21997421

  18. Abnormal structure of frontostriatal brain systems is associated with aspects of impulsivity and compulsivity in cocaine dependence

    PubMed Central

    Barnes, Anna; Simon Jones, P.; Morein-Zamir, Sharon; Robbins, Trevor W.; Bullmore, Edward T.

    2011-01-01

    A growing body of preclinical evidence indicates that addiction to cocaine is associated with neuroadaptive changes in frontostriatal brain systems. Human studies in cocaine-dependent individuals have shown alterations in brain structure, but it is less clear how these changes may be related to the clinical phenotype of cocaine dependence characterized by impulsive behaviours and compulsive drug-taking. Here we compared self-report, behavioural and structural magnetic resonance imaging data on a relatively large sample of cocaine-dependent individuals (n = 60) with data on healthy volunteers (n = 60); and we investigated the relationships between grey matter volume variation, duration of cocaine use, and measures of impulsivity and compulsivity in the cocaine-dependent group. Cocaine dependence was associated with an extensive system of abnormally decreased grey matter volume in orbitofrontal, cingulate, insular, temporoparietal and cerebellar cortex, and with a more localized increase in grey matter volume in the basal ganglia. Greater duration of cocaine dependence was correlated with greater grey matter volume reduction in orbitofrontal, cingulate and insular cortex. Greater impairment of attentional control was associated with reduced volume in insular cortex and increased volume of caudate nucleus. Greater compulsivity of drug use was associated with reduced volume in orbitofrontal cortex. Cocaine-dependent individuals had abnormal structure of corticostriatal systems, and variability in the extent of anatomical changes in orbitofrontal, insular and striatal structures was related to individual differences in duration of dependence, inattention and compulsivity of cocaine consumption. PMID:21690575

  19. Abnormal hippocampal structure and function in clinical anxiety and comorbid depression.

    PubMed

    Cha, Jiook; Greenberg, Tsafrir; Song, Inkyung; Blair Simpson, Helen; Posner, Jonathan; Mujica-Parodi, Lilianne R

    2016-05-01

    Given the high prevalence rates of comorbidity of anxiety and depressive disorders, identifying a common neural pathway to both disorders is important not only for better diagnosis and treatment, but also for a more complete conceptualization of each disease. Hippocampal abnormalities have been implicated in anxiety and depression, separately; however, it remains unknown whether these abnormalities are also implicated in their comorbidity. Here we address this question by testing 32 adults with generalized anxiety disorder (15 GAD only and 17 comorbid MDD) and 25 healthy controls (HC) using multimodal MRI (structure, diffusion and functional) and automated hippocampal segmentation. We demonstrate that (i) abnormal microstructure of the CA1 and CA2-3 is associated with GAD/MDD comorbidity and (ii) decreased anterior hippocampal reactivity in response to repetition of the threat cue is associated with GAD (with or without MDD comorbidity). In addition, mediation-structural equation modeling (SEM) reveals that our hippocampal and dimensional symptom data are best explained by a model describing a significant influence of abnormal hippocampal microstructure on both anxiety and depression-mediated through its impact on abnormal hippocampal threat processing. Collectively, our findings show a strong association between changes in hippocampal microstructure and threat processing, which together may present a common neural pathway to comorbidity of anxiety and depression.

  20. [Abnormal magnetic resonance imaging in a child with Alice in Wonderland syndrome following Epstein-Barr virus infection].

    PubMed

    Kamei, Atsushi; Sasaki, Makoto; Akasaka, Manami; Chida, Shoichi

    2002-07-01

    Characteristic pathologic changes of cranial computed tomography (CT) and magnetic resonance imaging (MRI) have never been reported in "Alice in Wonderland" syndrome (AIWS) caused by Epstein-Barr (EB) virus infection. We present here a 10-year-old girl with AIWS with an abnormal MR finding. During the course of serologically confirmed EB virus encephalopathy, she had distortion of the body image, visual hallucinations and depersonalization characteristic of AIWS. MRI demonstrated transient T2 prolongation and swelling of the cerebral cortex, especially at the bilateral temporal lobes, bilateral cingulate gyrus, right upper frontal gyrus, bilateral caudate nucleus, and bilateral putamen, whereas CT showed no abnormalities. Transient MRI lesions were occasionally reported in patients with EB virus encephalopathy/encephalitis who presented visual illusions and psychotic reactions, although the diagnosis of AIWS was not described. We consider that any patient with symptoms of AIWS should have MRI because the abnormal MRI findings may disappear in a short period. PMID:12134688

  1. Nuclear magnetic resonance in magnets with a helicoidal magnetic structure in an external magnetic field

    NASA Astrophysics Data System (ADS)

    Tankeyev, A. P.; Borich, M. A.; Smagin, V. V.

    2014-11-01

    In this review, the static and dynamic properties of a magnet with a helicoidal magnetic structure placed in an external magnetic field are discussed. The results of the investigation of its ground state and spectra, as well as the amplitudes of the spin excitations are presented. The temperature and field dependences of the basic thermodynamic characteristics (heat capacity, magnetization, and magnetic susceptibility) have been calculated in the spin-wave approximation. The results of calculating the local and integral dynamic magnetic susceptibility are given. This set of data represents a methodical basis for constructing a consistent (in the framework of unified approximations) picture of the NMR absorption in the magnet under consideration. Both local NMR characteristics (resonance frequency, line broadening, enhancement coefficient) and integral characteristics (resultant shape of the absorption line with its specific features) have been calculated. The effective Hamiltonian of the Suhl-Nakamura interaction of nuclear spins through spin waves has been constructed. The second moment and the local broadening of the line of the NMR absorption caused by this interaction have been calculated. The role of the basic local inhomogeneities in the formation of the integral line of the NMR absorption has been analyzed. The opportunities for the experimental NMR investigations in magnets with a chiral spin structure are discussed.

  2. Mutations in the SPTLC1 protein cause mitochondrial structural abnormalities and endoplasmic reticulum stress in lymphoblasts.

    PubMed

    Myers, Simon J; Malladi, Chandra S; Hyland, Ryan A; Bautista, Tara; Boadle, Ross; Robinson, Phillip J; Nicholson, Garth A

    2014-07-01

    Mutations in serine palmitoyltransferase long chain subunit 1 (SPTLC1) cause the typical length-dependent axonal degeneration hereditary sensory neuropathy type 1 (HSN1). Transmission electron microscopy studies on SPTLC1 mutant lymphoblasts derived from patients revealed specific structural abnormalities of mitochondria. Swollen mitochondria with abnormal cristae were clustered around the nucleus, with some mitochondria being wrapped in rough endoplasmic reticulum (ER) membranes. Total mitochondrial counts revealed a significant change in mitochondrial numbers between healthy and diseased lymphocytes but did not reveal any change in length to width ratios nor were there any changes to cellular function. However, there was a notable change in ER homeostasis, as assessed using key ER stress markers, BiP and ERO1-Lα, displaying reduced protein expression. The observations suggest that SPTLC1 mutations cause mitochondrial abnormalities and ER stress in HSN1 cells. PMID:24673574

  3. Fifty probands with extra structurally abnormal chromosomes characterized by fluorescence in situ hybridization

    SciTech Connect

    Blennow, E.; Telenius, H.; Nordenskjoeld, M.

    1995-01-02

    Extra structurally abnormal chromosomes (ESACs) are small supernumerary chromosomes often associated with developmental abnormalities and malformations. We present 50 probands with ESACs characterized by fluorescence in situ hybridization using centromere-specific probes and chromosome-specific libraries. ESAC-specific libraries were constructed by flow sorting and subsequent amplification by DOP-PCR. Using such ESAC-specific libraries we were able to outline the chromosome regions involved. Twenty-three of the 50 ESACs were inverted duplications of chromosome 15 (inv dup(15)), including patients with normal phenotypes and others with similar clinical symptoms. These 2 groups differed in size and shape of the inv dup(15). Patients with a large inv dup(15), which included the Prader-Willi region, had a high risk of abnormality, whereas patients with a small inv dup(15), not including the Prader-Willi region, were normal. ESACs derived from chromosomes 13 or 21 appeared to have a low risk of abnormality, while one out of 3 patients with an ESAC derived from chromosome 14 had discrete symptoms. One out of 3 patients with an ESAC derived from chromosome 22 had severe anomalies, corresponding to some of the manifestations of the cat eye syndrome. Small extra ring chromosomes of autosomal origin and ESACs identified as i(12p) or i(18p) were all associated with a high risk of abnormality. 42 refs., 2 figs., 2 tabs.

  4. Engineered Magnetic Core-Shell Structures.

    PubMed

    Alavi Nikje, Mir Mohammad; Vakili, Maryam

    2015-01-01

    In recent years, engineered magnetic core-shell structures are playing an important role in the wide range of various applications. These magnetic core-shell structures have attracted considerable attention because of their unique properties and various applications. Also, the synthesis of engineered magnetic core-shell structures has attracted practical interest because of potential applications in areas such as ferrofluids, medical imaging, drug targeting and delivery, cancer therapy, separations, and catalysis. So far a large number of engineered magnetic core-shell structures have been successfully synthesized. This review article focuses on the recent progress in synthesis and characterization of engineered magnetic core-shell structures. Also, this review gives a brief description of the various application of these structures. It is hoped that this review will play some small part in helping future developments in important field. PMID:26377655

  5. Abnormal interactions between context, memory structure, and mood in schizophrenia: an ERP investigation.

    PubMed

    Pinheiro, Ana P; Del Re, Elisabetta; Nestor, Paul G; Mezin, Jenna; Rezaii, Neguine; McCarley, Robert W; Gonçalves, Óscar F; Niznikiewicz, Margaret

    2015-01-01

    This study used event-related potentials to examine interactions between mood, sentence context, and semantic memory structure in schizophrenia. Seventeen male chronic schizophrenia and 15 healthy control subjects read sentence pairs after positive, negative, or neutral mood induction. Sentences ended with expected words (EW), within-category violations (WCV), or between-category violations (BCV). Across all moods, patients showed sensitivity to context indexed by reduced N400 to EW relative to both WCV and BCV. However, they did not show sensitivity to the semantic memory structure. N400 abnormalities were particularly enhanced under a negative mood in schizophrenia. These findings suggest abnormal interactions between mood, context processing, and connections within semantic memory in schizophrenia, and a specific role of negative mood in modulating semantic processes in this disease.

  6. Mutant laboratory mice with abnormalities in hair follicle morphogenesis, cycling, and/or structure: an update.

    PubMed

    Nakamura, Motonobu; Schneider, Marlon R; Schmidt-Ullrich, Ruth; Paus, Ralf

    2013-01-01

    Human hair disorders comprise a number of different types of alopecia, atrichia, hypotrichosis, distinct hair shaft disorders as well as hirsutism and hypertrichosis. Their causes vary from genodermatoses (e.g. hypotrichoses) via immunological disorders (e.g. alopecia areata, autoimmune cicatrical alopecias) to hormone-dependent abnormalities (e.g. androgenetic alopecia). A large number of spontaneous mouse mutants and genetically engineered mice develop abnormalities in hair follicle morphogenesis, cycling, and/or hair shaft formation, whose analysis has proven invaluable to define the molecular regulation of hair growth, ranging from hair follicle development, and cycling to hair shaft formation and stem cell biology. Also, the accumulating reports on hair phenotypes of mouse strains provide important pointers to better understand the molecular mechanisms underlying human hair growth disorders. Since numerous new mouse mutants with a hair phenotype have been reported since the publication of our earlier review on this matter a decade ago, we present here an updated, tabulated mini-review. The updated annotated tables list a wide selection of mouse mutants with hair growth abnormalities, classified into four categories: Mutations that affect hair follicle (1) morphogenesis, (2) cycling, (3) structure, and (4) mutations that induce extrafollicular events (for example immune system defects) resulting in secondary hair growth abnormalities. This synthesis is intended to provide a useful source of reference when studying the molecular controls of hair follicle growth and differentiation, and whenever the hair phenotypes of a newly generated mouse mutant need to be compared with existing ones.

  7. Dissociated Accumbens and Hippocampal Structural Abnormalities across Obesity and Alcohol Dependence

    PubMed Central

    Mak, Elijah; Chien, Yee; Voon, Valerie

    2016-01-01

    Background: Processing of food and drug rewards involves specific neurocircuitry, and emerging evidence implicates subcortical abnormalities, particularly the nucleus accumbens and hippocampus. We specifically hypothesized that these 2 established regions in addiction neurocircuitry are associated with distinctive in vivo structural abnormalities in obesity and alcohol dependence. Methods: To specifically investigate anatomically discrete volumetric changes associated with overconsumption of different rewards, we acquired T1 MRI data from 118 subjects in 3 groups comprising obesity (n=42), alcohol dependence (n=32), and healthy volunteer controls (n=44). To exploit novel methods of automated hippocampal subfield segmentation, we used Freesurfer software to generate volumetric data in subject groups for the hippocampal subiculum and its major striatal efferent target, the nucleus accumbens. Hypothesis-led, selective group difference comparisons were analyzed. Results: We found markedly greater accumbens volumes (P=.002) and relatively preserved hippocampal subfield volumes in obesity. Conversely, in alcohol dependence, we found preserved accumbens volumes but atrophy of specific ventral hippocampal subfields, the subiculum and presubiculum. Smaller global subcortical gray-matter volume was found in the alcohol dependence group only. Conclusions: Reward neurocircuitry including the accumbens and ventral hippocampus may show key structural abnormalities in disorders involving processing of both food and drug rewards, although the foci of disruption may vary as a function of reward modality. Structural differences may subserve altered reward and motivational processes in obesity and alcohol dependence and represent a potential biomarker for therapeutic targeting in key public health disorders. PMID:27207916

  8. The sun's magnetic sector structure

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.; Wilcox, J. M.; Scherrer, P. H.; Howard, R.

    1975-01-01

    The synoptic appearance of solar magnetic sectors is studied using 454 sector boundaries observed at earth from 1959 to 1973. The sectors are clearly visible in the photospheric magnetic field. Sector boundaries can be clearly identified as north-south demarcation lines between regions of persistent magnetic-polarity imbalances. These regions extend up to about 35 deg in latitude on both sides of the equator. They generally do not extend into the polar caps. The polar-cap boundary can be identified as an east-west demarcation line marking the poleward limit of the sectors. The typical flux imbalance for a magnetic sector is about 4 by 10 to the 21st power Mx.

  9. The sun's magnetic sector structure

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.; Wilcox, J. M.; Scherrer, P. H.; Howard, R.

    1975-01-01

    The synoptic appearance of solar magnetic sectors is studied using 454 sector boundaries observed at earth during 1959-1973. The sectors are clearly visible in the photospheric magnetic field. Sector boundaries can be clearly identified as north-south running demarcation lines between regions of persistent magnetic polarity imbalances. These regions extend up to about 35 deg of latitude on both sides of the equator. They generally do not extend into the polar caps. The polar cap boundary can be identified as an east-west demarcation line marking the poleward limit of the sectors. The typical flux imbalance for a magnetic sector is about 4 x 10 to the 21st power Maxwells.

  10. Abnormal Vertical Structure of Water Vapor over Taklamakan Desert from COSMIC Observations

    NASA Astrophysics Data System (ADS)

    Wang, J. K.; Liu, X. Y.; Yin, H. T.

    2012-04-01

    Water vapor is an important greenhouse gas. The vertical structure of the water vapor has a great impact on the weather and the climate. The Taklamakan desert is the largest desert in China, surrounded by a series of high mountains. The vertical structures of the water vapor over the Taklamakan desert have rarely been described by former research, due to the lack of conventional observations. This work is the first result of the water vapor vertical structure over the Taklamakan desert and its surroundings (35N-47N, 75E-94E) from the COSMIC occultation observations. Analysis found that a humid layer frequently occurs at the average height of 4800m. An "abnormal profile" was defined if a peak was observed in mid-troposphere in the humidity profile. This "abnormal profile" appeared in 24% of the total profile and appeared much more often inside the desert than outside during the year 2008 to 2010. Based on model analysis, two possible mechanisms were proposed to explain the reason of the formation of the abnormal profile. Through the statistics, 53% of total "abnormal profiles" were due to the transported water vapor topographic uplift effect, the topography of the desert forces the east-blowing wind to climb the surrounding mountains, bringing the low-altitude water vapor to mid-troposphere above the desert. The rest were due to the lack of water content in the air close to the ground. This new discovery and its possible explanations will help us to understand more about the climate of the Taklamakan desert and possibly also other similar regions.

  11. Defining myocardial tissue abnormalities in end-stage renal failure with cardiac magnetic resonance imaging using native T1 mapping.

    PubMed

    Rutherford, Elaine; Talle, Mohammed A; Mangion, Kenneth; Bell, Elizabeth; Rauhalammi, Samuli M; Roditi, Giles; McComb, Christie; Radjenovic, Aleksandra; Welsh, Paul; Woodward, Rosemary; Struthers, Allan D; Jardine, Alan G; Patel, Rajan K; Berry, Colin; Mark, Patrick B

    2016-10-01

    Noninvasive quantification of myocardial fibrosis in end-stage renal disease is challenging. Gadolinium contrast agents previously used for cardiac magnetic resonance imaging (MRI) are contraindicated because of an association with nephrogenic systemic fibrosis. In other populations, increased myocardial native T1 times on cardiac MRI have been shown to be a surrogate marker of myocardial fibrosis. We applied this method to 33 incident hemodialysis patients and 28 age- and sex-matched healthy volunteers who underwent MRI at 3.0T. Native T1 relaxation times and feature tracking-derived global longitudinal strain as potential markers of fibrosis were compared and associated with cardiac biomarkers. Left ventricular mass indices were higher in the hemodialysis than the control group. Global, Septal and midseptal T1 times were all significantly higher in the hemodialysis group (global T1 hemodialysis 1171 ± 27 ms vs. 1154 ± 32 ms; septal T1 hemodialysis 1184 ± 29 ms vs. 1163 ± 30 ms; and midseptal T1 hemodialysis 1184 ± 34 ms vs. 1161 ± 29 ms). In the hemodialysis group, T1 times correlated with left ventricular mass indices. Septal T1 times correlated with troponin and electrocardiogram-corrected QT interval. The peak global longitudinal strain was significantly reduced in the hemodialysis group (hemodialysis -17.7±5.3% vs. -21.8±6.2%). For hemodialysis patients, the peak global longitudinal strain significantly correlated with left ventricular mass indices (R = 0.426), and a trend was seen for correlation with galectin-3, a biomarker of cardiac fibrosis. Thus, cardiac tissue properties of hemodialysis patients consistent with myocardial fibrosis can be determined noninvasively and associated with multiple structural and functional abnormalities.

  12. Evaluation of magnetic resonance imaging abnormalities in juvenile onset neuropsychiatric systemic lupus erythematosus.

    PubMed

    Al-Obaidi, M; Saunders, D; Brown, S; Ramsden, L; Martin, N; Moraitis, E; Pilkington, C A; Brogan, P A; Eleftheriou, D

    2016-10-01

    The aim of this study was to describe the abnormalities identified with conventional MRI in children with neuropsychiatric systemic lupus erythematosus (NPSLE). This was single-centre (Great Ormond Street Hospital, London) retrospective case series of patients with juvenile NPSLE seen in 2003-2013. Brain MR images of the first episode of active NPSLE were reviewed. All patients fulfilled the 1999 ACR case definitions for NPSLE syndromes. Presenting neuropsychiatric manifestations, immunological findings and treatment are reported. Results are expressed as median and ranges or percentages. Fisher's exact test was used to identify clinical predictors of abnormal MRI. A total of 27 patients (22 females), median age 11 years (4-15), were identified. Presenting clinical symptoms included the following: headaches (85.1 %), mood disorder/depression (62.9 %), seizures (22.2 %), acute psychosis (18.5 %), cognitive dysfunction (14.8 %), movement disorder (14.8 %), acute confusional state (14.8 %), aseptic meningitis (7.4 %), demyelinating syndrome (3.7 %), myelopathy (3.7 %), dysautonomia (3.7 %) and cranial neuropathy (3.7 %). The principal MR findings were as follows: (1) absence of MRI abnormalities despite signs and symptoms of active NPSLE (59 %); (2) basilar artery territory infarction (3 %); (3) focal white matter hyperintensities on T2-weighted imaging (33 %); (4) cortical grey matter lesions (3 %); and (5) brain atrophy (18.5 %). The presence of an anxiety disorder strongly associated with abnormal MRI findings (p = 0.008). In over half the children with NPSLE, no conventional MRI abnormalities were observed; white matter hyperintensities were the most commonly described abnormalities. Improved MR techniques coupled with other alternative diagnostic imaging modalities may improve the detection rate of brain involvement in juvenile NPSLE. PMID:27527090

  13. Magnetic field structure evolution in rotating magnetic field plasmas

    SciTech Connect

    Petrov, Yuri; Yang Xiaokang; Huang, T.-S.

    2008-07-15

    A study of magnetic field structure evolution during 40-ms plasma discharge has been performed in a new device with 80 cm long/40 cm diameter cylindrical chamber, in which a plasma current I{sub p}{approx_equal}2 kA was driven and sustained by a rotating magnetic field. The main focus of the experiments is on how the changes in externally applied magnetic field affect the current profile and magnetic field in plasma. During plasma discharge, a pulse current was briefly fed to a magnetic coil located at the midplane (middle coil). The magnetic field in cross section of plasma was scanned with pickup probes. Two regimes were studied: without and with an external toroidal field (TF) produced by axial I{sub z} current. With a relatively small current (I{sub m} {<=} 600 A) in the middle coil, the plasma current is boosted up to 5 kA. The magnetic flux surfaces become extended along the axial Z direction, sometimes with the formation of doublet shape plasma. The regime without TF appears to be less stable, presumably due to the reversal of plasma current in central area of plasma column.

  14. Structural alloys for high field superconducting magnets

    SciTech Connect

    Morris, J.W. Jr.

    1985-08-01

    Research toward structural alloys for use in high field superconducting magnets is international in scope, and has three principal objectives: the selection or development of suitable structural alloys for the magnet support structure, the identification of mechanical phenomena and failure modes that may influence service behavior, and the design of suitable testing procedures to provide engineering design data. This paper reviews recent progress toward the first two of these objectives. The structural alloy needs depend on the magnet design and superconductor type and differ between magnets that use monolithic and those that employ force-cooled or ICCS conductors. In the former case the central requirement is for high strength, high toughness, weldable alloys that are used in thick sections for the magnet case. In the latter case the need is for high strength, high toughness alloys that are used in thin welded sections for the conductor conduit. There is productive current research on both alloy types. The service behavior of these alloys is influenced by mechanical phenomena that are peculiar to the magnet environment, including cryogenic fatigue, magnetic effects, and cryogenic creep. The design of appropriate mechanical tests is complicated by the need for testing at 4/sup 0/K and by rate effects associated with adiabatic heating during the tests. 46 refs.

  15. Phenotyping structural abnormalities in mouse embryos using high-resolution episcopic microscopy

    PubMed Central

    Weninger, Wolfgang J.; Geyer, Stefan H.; Martineau, Alexandrine; Galli, Antonella; Adams, David J.; Wilson, Robert; Mohun, Timothy J.

    2014-01-01

    The arrival of simple and reliable methods for 3D imaging of mouse embryos has opened the possibility of analysing normal and abnormal development in a far more systematic and comprehensive manner than has hitherto been possible. This will not only help to extend our understanding of normal tissue and organ development but, by applying the same approach to embryos from genetically modified mouse lines, such imaging studies could also transform our knowledge of gene function in embryogenesis and the aetiology of developmental disorders. The International Mouse Phenotyping Consortium is coordinating efforts to phenotype single gene knockouts covering the entire mouse genome, including characterising developmental defects for those knockout lines that prove to be embryonic lethal. Here, we present a pilot study of 34 such lines, utilising high-resolution episcopic microscopy (HREM) for comprehensive 2D and 3D imaging of homozygous null embryos and their wild-type littermates. We present a simple phenotyping protocol that has been developed to take advantage of the high-resolution images obtained by HREM and that can be used to score tissue and organ abnormalities in a reliable manner. Using this approach with embryos at embryonic day 14.5, we show the wide range of structural abnormalities that are likely to be detected in such studies and the variability in phenotypes between sibling homozygous null embryos. PMID:25256713

  16. Structure and Magnetism in Superconducting Iron Chalcogenides

    NASA Astrophysics Data System (ADS)

    Thampy, Vivek

    Iron superconductors are unique in that they provide a wide range of control parameters such as structure, chemical composition, pressure and impurities that can be tuned to provide insight into the underlying mechanisms of cooper pairing. In this dissertation, we will discuss the relationship of superconductivity with a) crystal structure, b) magnetic order, c) impurities, and d) low energy magnetic excitations in the structurally simplest iron superconductors, (Fe 1+yTe1-xSex). We use thin films of FeTe0.5Se0.5, in which the structural parameters are modulated using different growth conditions, to demonstrate the importance of the Te/Se height to superconductivity and show that it is consistent with the s± pairing symmetry. The proximity of magnetism and superconductivity in the iron superconductors is delved into for the iron chalcogenide superconductors by tracking the evolution of magnetic order and superconductivity with dopant (Se) concentration. We elucidate the pivotal role played by iron impurities, occupying interstitial sites in Fe1+yTe0.62Se0.38, in the microscopic origin of the quasi-static magnetism at (½,0). We used polarized and unpolarized neutron scattering, simulations of the scattering function based on structural data, and a semi-metallic 5-band model with super-exchange interactions with the interstitial iron to show the formation of magnetic polarons around the interstitial iron atoms which seed the observed (½,0) magnetism. Though the quasi-static magnetism occurs at (½,0), the low energy spin dynamics are dominated by the (½,½) fluctuations, like other iron based superconductors. We examine the characteristics of the signature feature in the low energy inelastic neutron scattering spectrum - the so-called spin resonance, and try to glean its microscopic origin by studying the effect of magnetic fields on the resonance.

  17. Multimodal Highlighting of Structural Abnormalities in Diabetic Rat and Human Corneas

    PubMed Central

    Kowalczuk, Laura; Latour, Gaël; Bourges, Jean-Louis; Savoldelli, Michèle; Jeanny, Jean-Claude; Plamann, Karsten; Schanne-Klein, Marie-Claire; Behar-Cohen, Francine

    2013-01-01

    Purpose This study aimed to highlight structural corneal changes in a model of type 2 diabetes, using in vivo corneal confocal microscopy (CCM). The abnormalities were also characterized by transmission electron microscopy (TEM) and second harmonic generation (SHG) microscopy in rat and human corneas. Methods Goto-Kakizaki (GK) rats were observed at age 12 weeks (n = 3) and 1 year (n = 6), and compared to age-matched controls. After in vivo CCM examination, TEM and SHG microscopy were used to characterize the ultrastructure and the three-dimensional organization of the abnormalities. Human corneas from diabetic (n = 3) and nondiabetic (n = 3) patients were also included in the study. Results In the basal epithelium of GK rats, CCM revealed focal hyper-reflective areas, and histology showed proliferative cells with irregular basement membrane. In the anterior stroma, extracellular matrix modifications were detected by CCM and confirmed in histology. In the Descemet's membrane periphery of all the diabetic corneas, hyper-reflective deposits were highlighted using CCM and characterized as long-spacing collagen fibrils by TEM. SHG microscopy revealed these deposits with high contrast, allowing specific detection in diabetic human and rat corneas without preparation and characterization of their three-dimensional organization. Conclusion Pathologic findings were observed early in the development of diabetes in GK rats. Similar abnormalities have been found in corneas from diabetic patients. Translational Relevance This multidisciplinary study highlights diabetes-induced corneal abnormalities in an animal model, but also in diabetic donors. This could constitute a potential early marker for diagnosis of hyperglycemia-induced tissue changes. PMID:24049714

  18. Abnormalities in hyperpolarized (129)Xe magnetic resonance imaging and spectroscopy in two patients with pulmonary vascular disease.

    PubMed

    Dahhan, Talal; Kaushik, Shiv S; He, Mu; Mammarappallil, Joseph G; Tapson, Victor F; McAdams, Holman P; Sporn, Thomas A; Driehuys, Bastiaan; Rajagopal, Sudarshan

    2016-03-01

    The diagnosis of pulmonary vascular disease (PVD) is usually based on hemodynamic and/or clinical criteria. Noninvasive imaging of the heart and proximal vasculature can also provide useful information. An alternate approach to such criteria in the diagnosis of PVD is to image the vascular abnormalities in the lungs themselves. Hyperpolarized (HP) (129)Xe magnetic resonance imaging (MRI) is a novel technique for assessing abnormalities in ventilation and gas exchange in the lungs. We applied this technique to two patients for whom there was clinical suspicion of PVD. Two patients who had significant hypoxemia and dyspnea with no significant abnormalities on computed tomography imaging or ventilation-perfusion scan and only mild or borderline pulmonary arterial hypertension at catheterization were evaluated. They underwent HP (129)Xe imaging and subsequently had tissue diagnosis obtained from lung pathology. In both patients, HP (129)Xe imaging demonstrated normal ventilation but markedly decreased gas transfer to red blood cells with focal defects on imaging, a pattern distinct from those previously described for idiopathic pulmonary fibrosis or obstructive lung disease. Pathology on both patients later demonstrated severe PVD. These findings suggest that HP (129)Xe MRI may be useful in the diagnosis of PVD and monitoring response to therapy. Further studies are required to determine its sensitivity and specificity in these settings. PMID:27162620

  19. Functional and structural abnormalities associated with empathy in patients with schizophrenia: An fMRI and VBM study.

    PubMed

    Singh, Sadhana; Modi, Shilpi; Goyal, Satnam; Kaur, Prabhjot; Singh, Namita; Bhatia, Triptish; Deshpande, Smita N; Khushu, Subash

    2015-06-01

    Empathy deficit is a core feature of schizophrenia which may lead to social dysfunction. The present study was carried out to investigate functional and structural abnormalities associated with empathy in patients with schizophrenia using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 schizophrenia patients and 14 healthy control subjects matched for age, sex and education were examined with structural highresolution T1-weighted MRI; fMRI images were obtained during empathy task in the same session. The analysis was carried out using SPM8 software. On behavioural assessment, schizophrenic patients (83.00+-29.04) showed less scores for sadness compared to healthy controls (128.70+-22.26) (p less than 0.001). fMRI results also showed reduced clusters of activation in the bilateral fusiform gyrus, left lingual gyrus, left middle and inferior occipital gyrus in schizophrenic subjects as compared to controls during empathy task. In the same brain areas, VBM results also showed reduced grey and white matter volumes. The present study provides an evidence for an association between structural alterations and disturbed functional brain activation during empathy task in persons affected with schizophrenia. These findings suggest a biological basis for social cognition deficits in schizophrenics. PMID:25963262

  20. Functional and structural abnormalities associated with empathy in patients with schizophrenia: An fMRI and VBM study

    PubMed Central

    Singh, Sadhana; Modi, Shilpi; Goyal, Satnam; Kaur, Prabhjot; Singh, Namita; Bhatia, Triptish; Deshpande, Smita N; Khushu, Subash

    2016-01-01

    Empathy deficit is a core feature of schizophrenia which may lead to social dysfunction. The present study was carried out to investigate functional and structural abnormalities associated with empathy in patients with schizophrenia using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 schizophrenia patients and 14 healthy control subjects matched for age, sex and education were examined with structural high-resolution T1-weighted MRI; fMRI images were obtained during empathy task in the same session. The analysis was carried out using SPM8 software. On behavioural assessment, schizophrenic patients (83.00±29.04) showed less scores for sadness compared to healthy controls (128.70±22.26) (p<0.001). fMRI results also showed reduced clusters of activation in the bilateral fusiform gyrus, left lingual gyrus, left middle and inferior occipital gyrus in schizophrenic subjects as compared to controls during empathy task. In the same brain areas, VBM results also showed reduced grey and white matter volumes. The present study provides an evidence for an association between structural alterations and disturbed functional brain activation during empathy task in persons affected with schizophrenia. These findings suggest a biological basis for social cognition deficits in schizophrenics. PMID:25963262

  1. Functional and structural abnormalities associated with empathy in patients with schizophrenia: An fMRI and VBM study.

    PubMed

    Singh, Sadhana; Modi, Shilpi; Goyal, Satnam; Kaur, Prabhjot; Singh, Namita; Bhatia, Triptish; Deshpande, Smita N; Khushu, Subash

    2015-06-01

    Empathy deficit is a core feature of schizophrenia which may lead to social dysfunction. The present study was carried out to investigate functional and structural abnormalities associated with empathy in patients with schizophrenia using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 schizophrenia patients and 14 healthy control subjects matched for age, sex and education were examined with structural highresolution T1-weighted MRI; fMRI images were obtained during empathy task in the same session. The analysis was carried out using SPM8 software. On behavioural assessment, schizophrenic patients (83.00+-29.04) showed less scores for sadness compared to healthy controls (128.70+-22.26) (p less than 0.001). fMRI results also showed reduced clusters of activation in the bilateral fusiform gyrus, left lingual gyrus, left middle and inferior occipital gyrus in schizophrenic subjects as compared to controls during empathy task. In the same brain areas, VBM results also showed reduced grey and white matter volumes. The present study provides an evidence for an association between structural alterations and disturbed functional brain activation during empathy task in persons affected with schizophrenia. These findings suggest a biological basis for social cognition deficits in schizophrenics.

  2. Usefulness of screening cardiovascular magnetic resonance imaging to detect aortic abnormalities after repair of coarctation of the aorta.

    PubMed

    Tsai, Shane F; Trivedi, Mira; Boettner, Bethany; Daniels, Curt J

    2011-01-15

    Guidelines recommend screening cardiovascular magnetic resonance (Sc-CMR) imaging for all patients after coarctation of the aorta repair, although there are limited data verifying its clinical utility. Therefore, we sought to assess the value of Sc-CMR in detecting aortic complications and at-risk abnormalities after coarctation of the aorta repair and to identify significant risk factors. We reviewed 76 patients (mean age 31 ± 10 years), including 40 with symptomatically indicated CMR (Sx-CMR) and 36 with Sc-CMR studies. CMR angiograms were evaluated for aortic abnormalities. Recoarctation was defined as residual narrowing/descending aorta at the diaphragm ≤0.5 (at risk ≤0.75), ascending aorta aneurysm as maximum ascending cross-sectional area/height ≥10 (at risk ≥5), and descending aorta aneurysm as maximum descending diameter/descending aorta at the diaphragm ≥1.5 (at risk ≥1.25). Aortic complications or abnormalities were found in 45 patients (59%). No patient met criteria for recoarctation (at risk 10 Sx-CMR vs 5 Sc-CMR). Significant risk factors included heart failure symptoms and female gender (p <0.05). One patient (Sc-CMR) had ascending aneurysm (at risk 17 Sx-CMR vs 8 Sc-CMR). Time from repair was a significant predictor (p <0.05). There were 10 patients (6 Sx-CMR vs 4 Sc-CMR) with descending aneurysm (at risk 8 Sx-CMR vs 7 Sc-CMR). Cardiovascular symptoms, hypertension, and echocardiogram were not predictive. In conclusion, >50% of patients undergoing Sc-CMR had aortic abnormalities, which was not significantly different from those undergoing Sx-CMR. In particular, Sc-CMR identified descending aorta aneurysms that were not predicted by clinical parameters or echocardiogram.

  3. Structure of magnetic fields in spiral galaxies

    NASA Astrophysics Data System (ADS)

    Kotarba, Hanna; Lesch, H.; Dolag, K.; Naab, T.; Johansson, P. H.; Stasyszyn, F. A.

    2009-04-01

    We present a set of global, self-consistent N-body/SPH simulations of the dynamic evolution of galactic discs with gas and including magnetic fields. We have implemented a description to follow the ideal induction equation in the SPH part of the code Vine. Results from a direct implementation of the field equations are compared to a representation by Euler potentials, which pose a ∇ ċ B-free description, a constraint not fulfilled for the direct implementation. All simulations are compared to an implementation of magnetic fields in the code Gadget. Starting with a homogeneous field we find a tight connection of the magnetic field structure to the density pattern of the galaxy in our simulations, with the magnetic field lines being aligned with the developing spiral pattern of the gas. Our simulations clearly show the importance of non-axisymmetry of the dynamic pattern for the evolution of the magnetic field.

  4. A Prospective Study of Overuse Knee Injuries Among Female Athletes With Muscle Imbalances and Structural Abnormalities

    PubMed Central

    Pescatello, Linda S.; Faghri, Pouran; Anderson, Jeffrey

    2004-01-01

    Objective: To prospectively examine the influence of hamstring-to-quadriceps (H:Q) ratio and structural abnormalities on the prevalence of overuse knee injuries among female collegiate athletes. Design and Setting: We used chi-square 2 × 2 contingency tables and the Fischer exact test to examine associations among H:Q ratios, structural abnormalities, and overuse knee injuries. Subjects: Fifty-three apparently healthy women (age = 19.4 ± 1.3 years, height = 167.6 ± 10.1 cm, mass = 65.0 ± 10.0 kg) from National Collegiate Athletic Association Division I women's field hockey (n = 23), soccer (n = 20), and basketball teams (n = 10) volunteered. Measurements: The H:Q ratio was determined from a preseason isokinetic test on a Biodex system at 60°/s and 300°/s. We measured athletes for genu recurvatum and Q-angles with a 14-in (35.56-cm) goniometer. Iliotibial band flexibility was assessed via the Ober test. Results: Ten overuse knee injuries (iliotibial band friction syndromes = 5, patellar tendinitis = 3, patellofemoral syndrome = 1, pes anserine tendinitis = 1) occurred in 9 athletes. The H:Q ratio below the normal range at 300°/s (P = 0.047) was associated with overuse knee injuries, as was the presence of genu recurvatum (P = 0.004). In addition, athletes possessing lower H:Q ratios at 300°/s and genu recurvatum incurred more overuse knee injuries than athletes without these abnormalities (P = 0.001). Conclusions: The presence of genu recurvatum and an H: Q ratio below normal range was associated with an increased prevalence of overuse knee injuries among female collegiate athletes. Further investigation is needed to clarify which preseason screening procedures may identify collegiate athletes who are susceptible to overuse knee injuries. PMID:15496997

  5. A Prospective Study of Overuse Knee Injuries Among Female Athletes With Muscle Imbalances and Structural Abnormalities.

    PubMed

    Devan, Michelle R; Pescatello, Linda S; Faghri, Pouran; Anderson, Jeffrey

    2004-09-01

    OBJECTIVE: To prospectively examine the influence of hamstring-to-quadriceps (H:Q) ratio and structural abnormalities on the prevalence of overuse knee injuries among female collegiate athletes. DESIGN AND SETTING: We used chi-square 2 x 2 contingency tables and the Fischer exact test to examine associations among H:Q ratios, structural abnormalities, and overuse knee injuries. SUBJECTS: Fifty-three apparently healthy women (age = 19.4 +/- 1.3 years, height = 167.6 +/- 10.1 cm, mass = 65.0 +/- 10.0 kg) from National Collegiate Athletic Association Division I women's field hockey (n = 23), soccer (n = 20), and basketball teams (n = 10) volunteered. MEASUREMENTS: The H:Q ratio was determined from a preseason isokinetic test on a Biodex system at 60 degrees /s and 300 degrees /s. We measured athletes for genu recurvatum and Q-angles with a 14-in (35.56-cm) goniometer. Iliotibial band flexibility was assessed via the Ober test. RESULTS: Ten overuse knee injuries (iliotibial band friction syndromes = 5, patellar tendinitis = 3, patellofemoral syndrome = 1, pes anserine tendinitis = 1) occurred in 9 athletes. The H:Q ratio below the normal range at 300 degrees /s (P = 0.047) was associated with overuse knee injuries, as was the presence of genu recurvatum (P = 0.004). In addition, athletes possessing lower H:Q ratios at 300 degrees /s and genu recurvatum incurred more overuse knee injuries than athletes without these abnormalities (P = 0.001). CONCLUSIONS: The presence of genu recurvatum and an H: Q ratio below normal range was associated with an increased prevalence of overuse knee injuries among female collegiate athletes. Further investigation is needed to clarify which preseason screening procedures may identify collegiate athletes who are susceptible to overuse knee injuries. PMID:15496997

  6. Functional changes are associated with tracheal structural abnormalities in patients with acromegaly

    PubMed Central

    Camilo, Gustavo Bittencourt; Guimarães, Fernando Silva; Mogami, Roberto; Faria, Alvaro Camilo Dias; Melo, Pedro Lopes

    2016-01-01

    Introduction Although impaired pulmonary function and respiratory sleep disorders are described as responsible for increased mortality in acromegalic patients, little is known about the tracheal abnormalities in this group of patients. Thus, the objectives of this study were to describe the tracheal structural abnormalities and correlate these changes with the respiratory function and clinical data of acromegalic patients. Material and methods This is a cross-sectional study that was carried out at two university hospitals. Twenty acromegalic patients underwent spirometry, forced oscillation technique, and computed tomography (CT) assessments. Dyspnea and daytime sleepiness were assessed using the Modified Medical Research Council (MMRC) scale and the Epworth Sleepiness Scale (ESS), respectively. Forty matched subjects served as controls. Results The acromegalic patients exhibited larger median ratios between forced expiratory flow and forced inspiratory flow at 50% of the forced vital capacity (FEF50%/FIF50%) (2.05 vs. 1.06, p = 0.0001) compared with healthy volunteers. In the CT analysis, acromegalic patients exhibited larger median differences between their cervical and thoracic tracheal diameters (Δ tracheal diameters) (3 vs. 1 mm; p = 0.003). An association was found between FEF50%/FIF50% and the following variables: mean resistance (Rm), cervical tracheal diameter, and Δ tracheal diameters. Rm also exhibited a negative correlation with cervical tracheal diameter. Neither the MMRC scale nor the ESS exhibited any significant correlation with large airway obstruction (LAO) indices or with the measured tracheal diameters. Conclusions Acromegalic patients have tracheal structural abnormalities which are associated with functional indicators of LAO but not with clinical data. PMID:26925121

  7. A Prospective Study of Overuse Knee Injuries Among Female Athletes With Muscle Imbalances and Structural Abnormalities.

    PubMed

    Devan, Michelle R; Pescatello, Linda S; Faghri, Pouran; Anderson, Jeffrey

    2004-09-01

    OBJECTIVE: To prospectively examine the influence of hamstring-to-quadriceps (H:Q) ratio and structural abnormalities on the prevalence of overuse knee injuries among female collegiate athletes. DESIGN AND SETTING: We used chi-square 2 x 2 contingency tables and the Fischer exact test to examine associations among H:Q ratios, structural abnormalities, and overuse knee injuries. SUBJECTS: Fifty-three apparently healthy women (age = 19.4 +/- 1.3 years, height = 167.6 +/- 10.1 cm, mass = 65.0 +/- 10.0 kg) from National Collegiate Athletic Association Division I women's field hockey (n = 23), soccer (n = 20), and basketball teams (n = 10) volunteered. MEASUREMENTS: The H:Q ratio was determined from a preseason isokinetic test on a Biodex system at 60 degrees /s and 300 degrees /s. We measured athletes for genu recurvatum and Q-angles with a 14-in (35.56-cm) goniometer. Iliotibial band flexibility was assessed via the Ober test. RESULTS: Ten overuse knee injuries (iliotibial band friction syndromes = 5, patellar tendinitis = 3, patellofemoral syndrome = 1, pes anserine tendinitis = 1) occurred in 9 athletes. The H:Q ratio below the normal range at 300 degrees /s (P = 0.047) was associated with overuse knee injuries, as was the presence of genu recurvatum (P = 0.004). In addition, athletes possessing lower H:Q ratios at 300 degrees /s and genu recurvatum incurred more overuse knee injuries than athletes without these abnormalities (P = 0.001). CONCLUSIONS: The presence of genu recurvatum and an H: Q ratio below normal range was associated with an increased prevalence of overuse knee injuries among female collegiate athletes. Further investigation is needed to clarify which preseason screening procedures may identify collegiate athletes who are susceptible to overuse knee injuries.

  8. A coronal plasmoid crossing a magnetic structure.

    NASA Astrophysics Data System (ADS)

    Delannee, C.; Koutchmy, S.

    1996-01-01

    The authors observed, during the solar eclipse in 1991, a coronal plasmoid. They analyzed the trajectory, the dynamic and radiative flux variation of the plasmoid. The motion is upward and decelerated. The flux presents a strong decrease. The plasmoid appears to go across a structure, which is supposed to follow the local magnetic field. It travels across the magnetic field line; this is not in agreement with the theory of the "melon seed" acceleration and additional forces are needed to explain the motion.

  9. Subsecond magnetic resonance angiography and the evaluation of abnormal arteriovasuclar communications

    NASA Astrophysics Data System (ADS)

    Zachariah, Anish B.; Pereles, F. S.; Kaliney, Ryan; Carr, James C.; Collins, Jeremy D.; Wood, Cecil; Finn, John P.

    2003-05-01

    Magnetic resonance (MR) angiography is becoming widely accepted in the diagnosis of vascular diseases. When used for evaluation of arterial stenoses, aneurysm, thrombosis, or occlusion, MR angiography is a robust and accurate technique. Traditional techniques for contrast-enhanced magnetic resonance angiography (MRA) offer the benefit of high spatial resolution in characterizing vascular malformations, but have lacked the temporal resolution to describe dynamic flow events. The purpose of this project is to demonstrate the potential role of a novel technique, sub-second MRA, in the evaluation of abdominal arteriovenous malformation.

  10. Integrating normal and abnormal personality structure: a proposal for DSM-V.

    PubMed

    Widiger, Thomas A

    2011-06-01

    The personality disorders section of the American Psychiatric Association's fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) is currently being developed. The purpose of the current paper is to encourage the authors of DSM-V to integrate normal and abnormal personality structure within a common, integrative model, and to suggest that the optimal choice for such an integration would be the five-factor model (FFM) of general personality structure. A proposal for the classification of personality disorder from the perspective of the FFM is provided. Discussed as well are implications and issues associated with an FFM of personality disorder, including validity, coverage, feasibility, clinical utility, and treatment implications.

  11. Structural and behavioral correlates of abnormal encoding of money value in the sensorimotor striatum in cocaine addiction.

    PubMed

    Konova, Anna B; Moeller, Scott J; Tomasi, Dardo; Parvaz, Muhammad A; Alia-Klein, Nelly; Volkow, Nora D; Goldstein, Rita Z

    2012-10-01

    Abnormalities in frontostriatal systems are thought to be central to the pathophysiology of addiction, and may underlie the maladaptive processing of the highly generalizable reinforcer, money. Although abnormal frontostriatal structure and function have been observed in individuals addicted to cocaine, it is less clear how individual variability in brain structure is associated with brain function to influence behavior. Our objective was to examine frontostriatal structure and neural processing of money value in chronic cocaine users and closely matched healthy controls. A reward task that manipulated different levels of money was used to isolate neural activity associated with money value. Gray matter volume measures were used to assess frontostriatal structure. Our results indicated that cocaine users had an abnormal money value signal in the sensorimotor striatum (right putamen/globus pallidus) that was negatively associated with accuracy adjustments to money and was more pronounced in individuals with more severe use. In parallel, group differences were also observed in both the function and gray matter volume of the ventromedial prefrontal cortex; in the cocaine users, the former was directly associated with response to money in the striatum. These results provide strong evidence for abnormalities in the neural mechanisms of valuation in addiction and link these functional abnormalities with deficits in brain structure. In addition, as value signals represent acquired associations, their abnormal processing in the sensorimotor striatum, a region centrally implicated in habit formation, could signal disadvantageous associative learning in cocaine addiction.

  12. Seismic probes of solar interior magnetic structure.

    PubMed

    Hanasoge, Shravan; Birch, Aaron; Gizon, Laurent; Tromp, Jeroen

    2012-09-01

    Sun spots are prominent manifestations of solar magnetoconvection, and imaging their subsurface structure is an outstanding problem of wide physical importance. Travel times of seismic waves that propagate through these structures are typically used as inputs to inversions. Despite the presence of strongly anisotropic magnetic waveguides, these measurements have always been interpreted in terms of changes to isotropic wave speeds and flow-advection-related Doppler shifts. Here, we employ partial-differential-equation-constrained optimization to determine the appropriate parametrization of the structural properties of the magnetic interior. Seven different wave speeds fully characterize helioseismic wave propagation: the isotropic sound speed, a Doppler-shifting flow-advection velocity, and an anisotropic magnetic velocity. The structure of magnetic media is sensed by magnetoacoustic slow and fast modes and Alfvén waves, each of which propagates at a different wave speed. We show that even in the case of weak magnetic fields, significant errors may be incurred if these anisotropies are not accounted for in inversions. Translation invariance is demonstrably lost. These developments render plausible the accurate seismic imaging of magnetoconvection in the Sun. PMID:23005276

  13. Seismic probes of solar interior magnetic structure.

    PubMed

    Hanasoge, Shravan; Birch, Aaron; Gizon, Laurent; Tromp, Jeroen

    2012-09-01

    Sun spots are prominent manifestations of solar magnetoconvection, and imaging their subsurface structure is an outstanding problem of wide physical importance. Travel times of seismic waves that propagate through these structures are typically used as inputs to inversions. Despite the presence of strongly anisotropic magnetic waveguides, these measurements have always been interpreted in terms of changes to isotropic wave speeds and flow-advection-related Doppler shifts. Here, we employ partial-differential-equation-constrained optimization to determine the appropriate parametrization of the structural properties of the magnetic interior. Seven different wave speeds fully characterize helioseismic wave propagation: the isotropic sound speed, a Doppler-shifting flow-advection velocity, and an anisotropic magnetic velocity. The structure of magnetic media is sensed by magnetoacoustic slow and fast modes and Alfvén waves, each of which propagates at a different wave speed. We show that even in the case of weak magnetic fields, significant errors may be incurred if these anisotropies are not accounted for in inversions. Translation invariance is demonstrably lost. These developments render plausible the accurate seismic imaging of magnetoconvection in the Sun.

  14. Functional and Structural Abnormalities in Deferoxamine Retinopathy: A Review of the Literature

    PubMed Central

    Di Nicola, Maura; Barteselli, Giulio; Dell'Arti, Laura; Ratiglia, Roberto; Viola, Francesco

    2015-01-01

    Deferoxamine mesylate (DFO) is the most commonly used iron-chelating agent to treat transfusion-related hemosiderosis. Despite the clear advantages for the use of DFO, numerous DFO-related systemic toxicities have been reported in the literature, as well as sight-threatening ocular toxicity involving the retinal pigment epithelium (RPE). The damage to the RPE can lead to visual field defects, color-vision defects, abnormal electrophysiological tests, and permanent visual deterioration. The purpose of this review is to provide an updated summary of the ocular findings, including both functional and structural abnormalities, in DFO-treated patients. In particular, we pay particular attention to analyzing results of multimodal technologies for retinal imaging, which help ophthalmologists in the early diagnosis and correct management of DFO retinopathy. Fundus autofluorescence, for example, is not only useful for screening patients at high-risk of DFO retinopathy, but is also a prerequisite for identify specific high-risk patterns of RPE changes that are relevant for the prognosis of the disease. In addition, optical coherence tomography may have a clinical usefulness in detecting extent and location of different retinal changes in DFO retinopathy. Finally, this review wants to underline the need for universally approved guidelines for screening and followup of this particular disease. PMID:26167477

  15. Structural characterization of copolymer embedded magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Nedelcu, G. G.; Nastro, A.; Filippelli, L.; Cazacu, M.; Iacob, M.; Rossi, C. Oliviero; Popa, A.; Toloman, D.; Dobromir, M.; Iacomi, F.

    2015-10-01

    Small magnetic nanoparticles (Fe3O4) were synthesized by co-precipitation and coated by emulsion polymerization with poly(methyl methacrylate-co-acrylic acid) (PMMA-co-AAc) to create surface functional groups that can attach drug molecules and other biomolecules. The coated and uncoated magnetite nanoparticles were stored for two years in normal closed ships and than characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy. The solid phase transformation of magnetite to maghemite, as well as an increase in particle size were evidenced for the uncoated nanoparticles. The coated nanoparticles preserved their magnetite structure and magnetic properties. The influences of monomers and surfactant layers on interactions between the magnetic nanoparticles evidenced that the thickness of the polymer has a significant effect on magnetic properties.

  16. Abnormal structural connectivity in the brain networks of children with hydrocephalus.

    PubMed

    Yuan, Weihong; Holland, Scott K; Shimony, Joshua S; Altaye, Mekibib; Mangano, Francesco T; Limbrick, David D; Jones, Blaise V; Nash, Tiffany; Rajagopal, Akila; Simpson, Sarah; Ragan, Dustin; McKinstry, Robert C

    2015-01-01

    Increased intracranial pressure and ventriculomegaly in children with hydrocephalus are known to have adverse effects on white matter structure. This study seeks to investigate the impact of hydrocephalus on topological features of brain networks in children. The goal was to investigate structural network connectivity, at both global and regional levels, in the brains in children with hydrocephalus using graph theory analysis and diffusion tensor tractography. Three groups of children were included in the study (29 normally developing controls, 9 preoperative hydrocephalus patients, and 17 postoperative hydrocephalus patients). Graph theory analysis was applied to calculate the global network measures including small-worldness, normalized clustering coefficients, normalized characteristic path length, global efficiency, and modularity. Abnormalities in regional network parameters, including nodal degree, local efficiency, clustering coefficient, and betweenness centrality, were also compared between the two patients groups (separately) and the controls using two tailed t-test at significance level of p < 0.05 (corrected for multiple comparison). Children with hydrocephalus in both the preoperative and postoperative groups were found to have significantly lower small-worldness and lower normalized clustering coefficient than controls. Children with hydrocephalus in the postoperative group were also found to have significantly lower normalized characteristic path length and lower modularity. At regional level, significant group differences (or differences at trend level) in regional network measures were found between hydrocephalus patients and the controls in a series of brain regions including the medial occipital gyrus, medial frontal gyrus, thalamus, cingulate gyrus, lingual gyrus, rectal gyrus, caudate, cuneus, and insular. Our data showed that structural connectivity analysis using graph theory and diffusion tensor tractography is sensitive to detect

  17. Magnetic field structure evolution in RMF plasmas

    NASA Astrophysics Data System (ADS)

    Petrov, Yuri; Yang, Xiaokang; Huang, Tian-Sen

    2007-11-01

    A study of magnetic field structure evolution during 40-ms plasma discharge had been performed in 80 cm long / 40 cm OD cylindrical chamber. Plasma current Ip˜2--3 kA is produced by applied 500 kHz rotating magnetic field. In experiments, the 2D profile of plasma current is changed by feeding a 10-ms pulse current to additional magnetic coil located at the midplane. Using newly developed magnetic field pick-up coils system, we scanned the magnetic field in cross-section of plasma. Two experimental regimes were studied: without external toroidal field (TF), and with TF produced by applied axial current. When a relatively small current (<0.5 kA) is applied to the midplane coil, in both cases the total plasma current measured with Rogowski coil experiences a jump (up to 100%), but the profile of current remains almost unchanged. When a larger current (1--2 kA) is applied to the midplane coil, the total plasma current drops; the magnetic structure changes differently in two regimes. In regime without TF, the magnetic field of plasma current is reversed at Rmagnetic field evolves during initial 1--3 ms transitional period of plasma formation.

  18. MULTISCALE DYNAMICS OF SOLAR MAGNETIC STRUCTURES

    SciTech Connect

    Uritsky, Vadim M.; Davila, Joseph M.

    2012-03-20

    Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries. We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.

  19. Multiscale Dynamics of Solar Magnetic Structures

    NASA Technical Reports Server (NTRS)

    Uritsky, Vadim M.; Davila, Joseph M.

    2012-01-01

    Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries.We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.

  20. Macro- and microscopic spectral-polarization characteristics of the structure of normal and abnormally located chordae tendianeae of left ventricular

    NASA Astrophysics Data System (ADS)

    Malyk, Yu. Yu.; Prydij, O. G.; Zymnyakov, D. A.; Alonova, M. V.; Ushakova, O. V.

    2013-12-01

    The morphological peculiarities of TS mitral valve of the heart of man in normal and abnormal spaced strings of the left ventricle and the study of their structural features depending on the location was studied. There are given the results of comparative statistics, correlation and fractal study population Mueller-matrix images (MMI) of healthy and abnormal (early forms that are not diagnosed by histological methods) BT normal and abnormally located tendon strings left ventricle of the human heart. Abnormalities in the structure of the wings, tendon strings (TS), mastoid muscle (MM) in inconsistencies elements and harmonized operation of all valve complex shown in the features of the polarization manifestations of it laser images.

  1. Abnormal behavior associated with a point mutation in the structural gene for monoamine oxidase A

    SciTech Connect

    Brunner, H.G. ); Nelen, M.; Ropers, H.H.; van Oost, B.A. )

    1993-10-22

    Genetic and metabolic studies have been done on a large kindred in which several males are affected by a syndrome of borderline mental retardation and abnormal behavior. The types of behavior that occurred include impulsive aggression, arson, attempted rape, and exhibitionism. Analysis of 24-hour urine samples indicated markedly disturbed monoamine metabolism. This syndrome was associated with a complete and selective deficiency of enzymatic activity of monoamine oxidase A (MAOA). In each of five affected males, a point mutation was identified in the eighth exon of the MAOA structural gene, which changes a glutamine to a termination codon. Thus, isolated complete MAOA deficiency in this family is associated with a recognizable behavioral phenotype that includes disturbed regulation of impulsive aggression.

  2. Structural brain abnormalities in the frontostriatal system and cerebellum in pedophilia.

    PubMed

    Schiffer, Boris; Peschel, Thomas; Paul, Thomas; Gizewski, Elke; Forsting, Michael; Leygraf, Norbert; Schedlowski, Manfred; Krueger, Tillmann H C

    2007-11-01

    Even though previous neuropsychological studies and clinical case reports have suggested an association between pedophilia and frontocortical dysfunction, our knowledge about the neurobiological mechanisms underlying pedophilia is still fragmentary. Specifically, the brain morphology of such disorders has not yet been investigated using MR imaging techniques. Whole brain structural T1-weighted MR images from 18 pedophile patients (9 attracted to males, 9 attracted to females) and 24 healthy age-matched control subjects (12 hetero- and 12 homosexual) from a comparable socioeconomic stratum were processed by using optimized automated voxel-based morphometry within multiple linear regression analyses. Compared to the homosexual and heterosexual control subjects, pedophiles showed decreased gray matter volume in the ventral striatum (also extending into the nucl. accumbens), the orbitofrontal cortex and the cerebellum. These observations further indicate an association between frontostriatal morphometric abnormalities and pedophilia. In this respect these findings may support the hypothesis that there is a shared etiopathological mechanism in all obsessive-compulsive spectrum disorders.

  3. Structural and Functional Coronary Artery Abnormalities in Patients With Vasospastic Angina Pectoris.

    PubMed

    Ong, Peter; Aziz, Ahmed; Hansen, Henrik Steen; Prescott, Eva; Athanasiadis, Anastasios; Sechtem, Udo

    2015-01-01

    Coronary spasm is involved in many clinical scenarios, such as stable angina, acute coronary syndrome, sudden cardiac death, non-ischemic cardiomyopathy, arrhythmia and syncope. In recent years, imaging tools such as computerized tomographic angiography, intravascular ultrasound or optical coherence tomography have been applied to study the coronary pathology in patients with vasospastic angina. Patients with vasospastic angina represent a heterogeneous cohort of patients with regard to the extent of concomitant coronary atherosclerosis. They share the common pathophysiological phenomenon of vascular smooth muscle hyperreactivity leading to spasm caused by various factors that may also overlap. Focal coronary spasm is related to epicardial atherosclerosis and in the presence of obstructive coronary artery disease it may be useful to treat the lesion to prevent further spasm. The aim of this article is to review structural and functional coronary artery abnormalities in patients with vasospastic angina.

  4. Functional Connectivity Abnormalities of Brain Regions with Structural Deficits in Young Adult Male Smokers

    PubMed Central

    Bu, Limei; Yu, Dahua; Su, Shaoping; Ma, Yao; von Deneen, Karen M.; Luo, Lin; Zhai, Jinquan; Liu, Bo; Cheng, Jiadong; Guan, Yanyan; Li, Yangding; Bi, Yanzhi; Xue, Ting; Lu, Xiaoqi; Yuan, Kai

    2016-01-01

    Smoking is one of the most prevalent dependence disorders. Previous studies have detected structural and functional deficits in smokers. However, few studies focused on the changes of resting state functional connectivity (RSFC) of the brain regions with structural deficits in young adult smokers. Twenty-six young adult smokers and 26 well-matched healthy non-smokers participated in our study. Voxel-based morphometry (VBM) and RSFC were employed to investigate the structural and functional changes in young adult smokers. Compared with healthy non-smokers, young smokers showed increased gray matter (GM) volume in the left putamen and decreased GM volume in the left anterior cingulate cortex (ACC). Moreover, GM volume in the left ACC has a negative correlation trend with pack-years and GM volume in the left putamen was positively correlated with pack-years. The left ACC and putamen with abnormal volumes were chosen as the regions of interest (ROIs) for the RSFC analysis. We found that smokers showed increased RSFC between the left ACC and right amygdala and between the left putamen and right anterior insula. We revealed structural and functional deficits within the frontostriatal circuits in young smokers, which may shed new insights into the neural mechanisms of smoking. PMID:27757078

  5. Magnetic structure of DyFe3

    NASA Astrophysics Data System (ADS)

    Jin, Long-huan; W, J. James; J, Rhyne; R, Lemaire

    1985-06-01

    Powder neutron diffraction measurements have been carried out on the intermetallic compound DyFe3 at 4 and 295K. The magnetic structure of the compound at 4 and 295K are noncollinear but coplanar in the a-c plane, and the moments of the Dy and Fe ions lie closer to the basal plane.

  6. High performance hybrid magnetic structure for biotechnology applications

    DOEpatents

    Humphries, David E.; Pollard, Martin J.; Elkin, Christopher J.

    2006-12-12

    The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides for separation and other biotechnology applications involving holding, manipulation, or separation of magnetic or magnetizable molecular structures and targets. Also disclosed are: a method of assembling the hybrid magnetic plates, a high throughput protocol featuring the hybrid magnetic structure, and other embodiments of the ferromagnetic pole shape, attachment and adapter interfaces for adapting the use of the hybrid magnetic structure for use with liquid handling and other robots for use in high throughput processes.

  7. Magnetic tension of sunspot fine structures

    NASA Astrophysics Data System (ADS)

    Venkatakrishnan, P.; Tiwari, Sanjiv Kumar

    2010-06-01

    Context. The equilibrium structure of sunspots depends critically on its magnetic topology and is dominated by magnetic forces. Tension force is one component of the Lorentz force, which balances the gradient of magnetic pressure in force-free configurations. Aims: We employ the tension term of the Lorentz force to clarify the structure of sunspot features like penumbral filaments, umbral light bridges, and outer penumbral fine structures. Methods: We computed the vertical component of the tension term of Lorentz force over two active regions, NOAA AR 10933 and NOAA AR 10930 observed on 5 January 2007 and 12 December 2006, respectively. The former is a simple active region while the latter is a complex one with highly sheared polarity inversion line (PIL). We obtained the vector magnetograms from Hinode(SOT/SP). Results: We find an inhomogeneous distribution of tension with both positive and negative signs in various features of the sunspots. The existence of positive tension at locations of lower field strength and higher inclination is compatible with the uncombed model of the penumbral structure. Positive tension is also seen in umbral light bridges, which could be indication of uncombed structure of the light bridge. Likewise, the upwardly directed tension associated with bipolar regions in the penumbra could be a direct confirmation of the sea serpent model of penumbral structures. Upwardly directed tension at the PIL of AR 10930 seems to be related to flux emergence. The magnitude of the tension force is greater than the force of gravity in some places, implying a nearly force-free configuration for these sunspot features. Conclusions: From our study, magnetic tension emerges as a useful diagnostic of the local equilibrium of the sunspot fine structures. Figures A.1-A.3 are only available in electronic form at http://www.aanda.org

  8. Underground structure of terrestrial mud volcanoes and abnormal water pressure formation in Niigata, Central JAPAN

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Shinya, T.; Miyata, Y.; Tokuyasu, S.

    2005-12-01

    Activity of mud volcano is thought to be caused by an abnormal water pressure generated in deep underground and make a serious problem for underground constructions such as railway tunnel, underground facility for radwaste and so on. It is important to investigate the underground structure of a mud volcano and the mechanism of abnormal water formation for site selection and safety assessment of such facilities. Serious trouble such as tunnel wall collapse due to the rock swelling has happened 180m deep under mud volcanoes. It took more than 10 years to excavate the section of 150 m long. 4 terrestrial mud volcanoes were found in the Tertiary sedimentary basin in Niigata, central Japan All the mud volcanoes are distributed along the rim of the topographic basin that is located at the NE-SW trending crest of mountainous area and distributed along the wing of anticline. Geological structure inside basin is heavily disturbed. The extinct mud volcano is exposed in the side-slope of newly constructed road and the internal vent structure of mud volcano can be observed. The vent is 30 m in diameter and is consisted of mud breccia and scaly network clay that is thought to be generated by hydro-fracturing and the following water-rock interaction between mudstone and groundwater. Groundwater erupted from mud volcano is highly saline with electric conductivity of 15 mS/cm and high 18 O/16 O isotope ratio of 1.2 parmillage. Also, the vitrinite reflectance is 1.5 to 1.9 % that is not expected in the sedimentary rocks exposed near ground surface. As a result, it is assumed that these erupted materials were introduced from the deep underground about 4000 m deep. CSA-MT geophysical exploration was carried out to survey the underground structure and obtained the profile of electrical resistivity from the surface to 800 m in depth. It is found that the disk-shaped low resistivity zone less than 1 m due to the high salinity content is identified in underground 600 m deep, 200 m thick

  9. Sensory migraine aura is not associated with structural grey matter abnormalities.

    PubMed

    Hougaard, Anders; Amin, Faisal Mohammad; Arngrim, Nanna; Vlachou, Maria; Larsen, Vibeke Andrée; Larsson, Henrik B W; Ashina, Messoud

    2016-01-01

    Migraine with aura (MA) is characterized by cortical dysfunction. Frequent aura attacks may alter cerebral cortical structure in patients, or structural grey matter abnormalities may predispose MA patients to aura attacks. In the present study we aimed to investigate cerebral grey matter structure in a large group of MA patients with and without sensory aura (i.e. gradually developing, transient unilateral sensory disturbances). We included 60 patients suffering from migraine with typical visual aura and 60 individually age and sex-matched controls. Twenty-nine of the patients additionally experienced sensory aura regularly. We analysed high-resolution structural MR images using two complimentary approaches and compared patients with and without sensory aura. Patients were also compared to controls. We found no differences of grey matter density or cortical thickness between patients with and without sensory aura and no differences for the cortical visual areas between patients and controls. The somatosensory cortex was thinner in patients (1.92 mm vs. 1.96 mm, P = 0.043) and the anterior cingulate cortex of patients had a decreased grey matter density (P = 0.039) compared to controls. These differences were not correlated to the clinical characteristics. Our results suggest that sensory migraine aura is not associated with altered grey matter structure and that patients with visual aura have normal cortical structure of areas involved in visual processing. The observed decreased grey matter volume of the cingulate gyrus in patients compared to controls have previously been reported in migraine with and without aura, but also in a wide range of other neurologic and psychiatric disorders. Most likely, this finding reflects general bias between patients and healthy controls.

  10. Structural analysis of suerconducting bending magnets

    SciTech Connect

    Meuser, R.B.

    1980-05-01

    Mechanical stresses, displacements, and the effects of displacements upon aberrations of the magnetic field in the aperture have been calculated for a class of superconducting bending-magnet configurations. The analytical model employed for the coil is one in which elements are free to slide without restraint upon each other, and upon the surrounding structure. Coil configurations considered range from an idealized one in which the current density varies as cosine theta to more realistic ones consisting of regions of uniform current density. With few exceptions, the results for the more realistic coils closely match those of the cos theta coil.

  11. Method and apparatus for control of a magnetic structure

    DOEpatents

    Challenger, Michael P.; Valla, Arthur S.

    1996-06-18

    A method and apparatus for independently adjusting the spacing between opposing magnet arrays in charged particle based light sources. Adjustment mechanisms between each of the magnet arrays and the supporting structure allow the gap between the two magnet arrays to be independently adjusted. In addition, spherical bearings in the linkages to the magnet arrays permit the transverse angular orientation of the magnet arrays to also be adjusted. The opposing magnet arrays can be supported above the ground by the structural support.

  12. Central motor conduction in multiple sclerosis: evaluation of abnormalities revealed by transcutaneous magnetic stimulation of the brain.

    PubMed Central

    Ingram, D A; Thompson, A J; Swash, M

    1988-01-01

    Magnetic stimulation of the brain and spinal column was used to assess conduction in the descending central motor pathways controlling arm and leg muscles of 20 patients with multiple sclerosis, and 10 normal subjects. The multiple sclerosis patients had relapsing and remitting disease but all were ambulant and in stable clinical remission. Increased central motor conduction times (CMCTs), up to three times normal, were frequently encountered in multiple sclerosis patients and in leg muscles these correlated closely with clinical signs of upper motor neuron disturbance; in the upper limb muscles a higher proportion of subclinical lesions was present. Weak muscles were almost invariably associated with abnormal central conduction but increased CMCTs were also found for 52 of the 104 muscles with normal strength. CMCTs for lower limb muscles were directly related (p less than 0.005) to functional motor disability (Kurtzke and Ambulatory Index Scales). No patient developed clinical evidence of relapse during follow-up of at least 8 months. Magnetic brain stimulation is easy to perform, painless, and safe, and provides clinically relevant information in the diagnosis and monitoring of multiple sclerosis patients. PMID:2837538

  13. Modeling Magnetic Flux-Ropes Structures

    NASA Astrophysics Data System (ADS)

    Nieves-Chinchilla, T.; Linton, M.; Hidalgo, M. A. U.; Vourlidas, A.; Savani, N.; Szabo, A.; Farrugia, C. J.; Yu, W.

    2015-12-01

    Flux-ropes are usually associated with magnetic structures embedded in the interplanetary Coronal Mass Ejections (ICMEs) with a depressed proton temperature (called Magnetic Clouds, MCs). However, small-scale flux-ropes in the solar wind are also identified with different formation, evolution, and dynamic involved. We present an analytical model to describe magnetic flux-rope topologies. The model is generalized to different grades of complexity. It extends the circular-cylindrical concept of Hidalgo et al. (2002) by introducing a general form for the radial dependence of the current density. This generalization provides information on the force distribution inside the flux rope in addition to the usual parameters of flux-rope geometrical information and orientation. The generalized model provides flexibility for implementation in 3-D MHD simulations.

  14. Abnormal Bone Mechanical and Structural Properties in Adolescent Idiopathic Scoliosis: A Study with Finite Element Analysis and Structural Model Index.

    PubMed

    Cheuk, K Y; Zhu, T Y; Yu, F W P; Hung, V W Y; Lee, K M; Qin, L; Cheng, J C Y; Lam, T P

    2015-10-01

    Previous studies found adolescent idiopathic scoliosis (AIS) is associated with low bone mineral density (BMD) and abnormal bone quality, whilst the association between AIS and their bone strength is unknown. From high-resolution peripheral quantitative computed tomography-generated images, bone mechanical properties can be evaluated with finite element analysis (FEA), and trabecular rod-plate configuration related to trabecular bone strength can be quantified by structure model index (SMI). This study aimed to compare trabecular configuration and bone mechanical properties between AIS and the controls. 95 AIS girls aged 12-14 years and 97 age- and gender-matched normal controls were recruited. Bilateral femoral necks and non-dominant distal radius were scanned by dual-energy X-ray absorptiometry for areal BMD and HR-pQCT for SMI and FEA, respectively. Subjects were further classified into osteopenic and non-osteopenic group based on their areal BMD. Bone mechanical properties (stiffness, failure load and apparent modulus) were calculated using FEA. Linear regression model was used for controlling age, physical activity and calcium intake. AIS was associated with lower failure load and apparent modulus after adjusting for age, whereas AIS was associated with lower apparent modulus after adjusting for all confounders. Osteopenic AIS was associated with more rod-like trabeculae when compared with non-osteopenic AIS, whereas no difference was detected between osteopenic and non-osteopenic controls. This might be the result of abnormal regulation and modulation of bone metabolism and bone modelling and remodelling in AIS which will warrant future studies with a longitudinal design to determine the significance of micro-architectural abnormalities in AIS.

  15. Potential diagnosis of hemodynamic abnormalities in patent ductus arteriosus by cine magnetic resonance imaging.

    PubMed

    Chien, C T; Lin, C S; Hsu, Y H; Lin, M C; Chen, K S; Wu, D J

    1991-10-01

    Cine magnetic resonance imaging was performed in 11 patients with communication between systemic and pulmonary circulation. In five patients with uncomplicated patent ductus arteriosus (PDA), ductus arteriosus was delineated by a persistent band of low signal intensity, whereas in two patients who also had severe pulmonary hypertension the signal intensity was varied. Two separate low signal intensities in the main pulmonary artery and the descending aorta were each uniformly recorded in the five patients with uncomplicated PDA, consistent with continuous left-to-right shunt and turbulent flow acceleration, respectively. In one of the patients with severe pulmonary hypertension but not Eisenmenger's syndrome, the areas of low signal intensity from left-to-right shunt and turbulent flow acceleration diminished. In the patient with Eisenmenger's PDA the right-to-left shunt was also characterized by an area of low signal intensity but with a reversal in direction. Cine MR imaging has the potential to be a noninvasive and supplemental method for evaluating PDA.

  16. Abnormal affective decision making revealed in adolescent binge drinkers using a functional magnetic resonance imaging study.

    PubMed

    Xiao, Lin; Bechara, Antoine; Gong, Qiyong; Huang, Xiaoqi; Li, Xiangrui; Xue, Gui; Wong, Savio; Lu, Zhong-Lin; Palmer, Paula; Wei, Yonglan; Jia, Yong; Johnson, C Anderson

    2013-06-01

    The goal of this study was to investigate the neural correlates of affective decision making, as measured by the Iowa Gambling Task (IGT), which are associated with adolescent binge drinking. Fourteen adolescent binge drinkers (16-18 years of age) and 14 age-matched adolescents who had never consumed alcohol--never drinkers--were recruited from local high schools in Chengdu, China. Questionnaires were used to assess academic performance, drinking experience, and urgency. Brain regions activated by the IGT performance were identified with functional magnetic resonance imaging. Results showed that, compared to never drinkers, binge drinkers performed worse on the IGT and showed higher activity in the subcomponents of the decision-making neural circuitry implicated in the execution of emotional and incentive-related behaviors, namely, the left amygdala and insula bilaterally. Moreover, measures of the severity of drinking problems in real life, as well as high urgency scores, were associated with increased activity within the insula, combined with decreased activity within the orbitofrontal cortex. These results suggest that hyperreactivity of a neural system implicated in the execution of emotional and incentive-related behaviors can be associated with socially undesirable behaviors, such as binge drinking, among adolescents. These findings have social implications because they potentially reveal underlying neural mechanisms for making poor decisions, which may increase an individual's risk and vulnerability for alcoholism.

  17. High performance hybrid magnetic structure for biotechnology applications

    DOEpatents

    Humphries, David E; Pollard, Martin J; Elkin, Christopher J

    2005-10-11

    The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides means for separation and other biotechnology applications involving holding, manipulation, or separation of magnetizable molecular structures and targets. Also disclosed are: a method of assembling the hybrid magnetic plates, a high throughput protocol featuring the hybrid magnetic structure, and other embodiments of the ferromagnetic pole shape, attachment and adapter interfaces for adapting the use of the hybrid magnetic structure for use with liquid handling and other robots for use in high throughput processes.

  18. High performance hybrid magnetic structure for biotechnology applications

    DOEpatents

    Humphries, David E.; Pollard, Martin J.; Elkin, Christopher J.

    2009-02-03

    The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides means for separation and other biotechnology applications involving holding, manipulation, or separation of magnetic or magnetizable molecular structures and targets. Also disclosed are further improvements to aspects of the hybrid magnetic structure, including additional elements and for adapting the use of the hybrid magnetic structure for use in biotechnology and high throughput processes.

  19. Pre-existing structural abnormalities of the limbic system in transient global amnesia.

    PubMed

    Park, Kang Min; Han, Yong Hee; Kim, Tae Hyung; Mun, Chi Woong; Shin, Kyong Jin; Ha, Sam Yeol; Park, JinSe; Kim, Sung Eun

    2015-05-01

    This study aimed to investigate the clinical and radiological findings in patients with transient global amnesia and to evaluate structural abnormalities using voxel-based morphometry. The subjects were diagnosed with transient global amnesia. For the voxel-based morphometry analyses, Statistical Parametric Mapping, running on the MATLAB platform (MathWorks, Natick, MA, USA), was employed to analyze the structural differences between patients with transient global amnesia and control subjects. Eighty patients met the inclusion criteria. Twenty-three patients (29%) were men, and 57 patients (71%) were women. There were significantly more women among the transient global amnesia patients compared with the general Korean population. MRI revealed hippocampal cavities in 41 patients (51%), and the incidence of such cavities was significantly different from that of the control subjects (24%). There were no differences in the clinical factors between the patients with and without hippocampal cavities. Diffusion-weighted imaging was performed in 54 patients, and 13 patients (24%) exhibited high signal intensity in the hippocampus. There were also no differences in the clinical factors between the patients with and without high signal intensities in the hippocampus on diffusion-weighted imaging. Twenty-six patients underwent three-dimensional volumetric T1-weighted imaging that produced results suitable for voxel-based morphometry, and these patients presented with gray matter volume reductions in the hippocampus, cingulum, and cerebellum. There were significant structural differences in the limbic structures between patients with transient global amnesia and the control subjects that might have contributed to vulnerability of the memory pathways of the patients with transient global amnesia.

  20. A Congenital Gerbode Defect associated with a Rare Structural Abnormality of the Mitral Valve Diagnosed in an Adult Patient

    PubMed Central

    Mateescu, Anca D.; Beladan, Carmen C.; Radulescu, Bogdan; Ginghina, Carmen; Popescu, Bogdan A.

    2016-01-01

    We report the case of a rare association of a congenital Gerbode defect with severe mitral regurgitation due to abnormal linear structure of mitral valve, diagnosed in an adult patient. The case highlights the importance of a thorough examination interpreting the echocardiographic findings on a pathophysiological basis. It also underlines the complementary role of different imaging techniques with transesophageal echocardiography, allowing the precise assessment of both structural and functional abnormalities in such a complex case. The patient underwent mitral valve replacement with a bileaflet mechanical prosthesis and repair of the Gerbode defect. The imaging findings were confirmed during the surgical procedure, leading to a good outcome. PMID:27721869

  1. Magnetic fine structure of solar coronal loops

    NASA Technical Reports Server (NTRS)

    Van Ballegooijen, A. A.

    1988-01-01

    A numerical simulation of the effect of a random photospheric flow on the magnetic structure of a coronal loop is presented. An initially uniform field embedded in a perfectly conducting plasma is assumed, extending between two flat parallel plates representing the solar photosphere at both ends of the loop. The field is perturbed by a sequence of randomly phased, sinusoidal flow patterns applied at one of the boundary plates, and the corresponding sequence of force-free fields is determined. It is found that the electric currents generated by these flows develop a fine structure on a scale significantly smaller than the wavelength of the velocity patterns. This suggests that magnetic energy is transferred to smaller scale via a cascade process.

  2. Magnetic Micro/Nano Structures for Biological Manipulation

    NASA Astrophysics Data System (ADS)

    Huang, Chen-Yu; Hsieh, Teng-Fu; Chang, Wei-Chieh; Yeh, Kun-Chieh; Hsu, Ming-Shinn; Chang, Ching-Ray; Chen, Jiann-Yeu; Wei, Zung-Hang

    2016-05-01

    Biomanipulation based on micro/nano structures is an attractive approach for biotechnology. To manipulate biological systems by magnetic forces, the magnetic labeling technology utilized magnetic nanoparticles (MNPs) as a common rule. Ferrofluid, well-dispersed MNPs, can be used for magnetic modification of the surface or as molds to form organized microstructures. For magnetic-based micro/nano structures, different methods to modulate magnetic field at the microscale have been developed. Specifically, this review focused on a new strategy which uses the concept of micromagnetism of patterned magnetic thin film with specific domain walls configurations to generate stable magnetic poles for cell patterning.

  3. Magnetic Micro/Nano Structures for Biological Manipulation

    NASA Astrophysics Data System (ADS)

    Huang, Chen-Yu; Hsieh, Teng-Fu; Chang, Wei-Chieh; Yeh, Kun-Chieh; Hsu, Ming-Shinn; Chang, Ching-Ray; Chen, Jiann-Yeu; Wei, Zung-Hang

    2016-05-01

    Biomanipulation based on micro/nano structures is an attractive approach for biotechnology. To manipulate biological systems by magnetic forces, the magnetic labeling technology utilized magnetic nanoparticles (MNPs) as a common rule. Ferrofluid, well-dispersed MNPs, can be used for magnetic modification of the surface or as molds to form organized microstructures. For magnetic-based micro/nano structures, different methods to modulate magnetic field at the microscale have been developed. Specifically, this review focused on a new strategy which uses the concept of micromagnetism of patterned magnetic thin film with specific domain walls configurations to generate stable magnetic poles for cell patterning.

  4. Filaggrin genotype in ichthyosis vulgaris predicts abnormalities in epidermal structure and function.

    PubMed

    Gruber, Robert; Elias, Peter M; Crumrine, Debra; Lin, Tzu-Kai; Brandner, Johanna M; Hachem, Jean-Pierre; Presland, Richard B; Fleckman, Philip; Janecke, Andreas R; Sandilands, Aileen; McLean, W H Irwin; Fritsch, Peter O; Mildner, Michael; Tschachler, Erwin; Schmuth, Matthias

    2011-05-01

    Although it is widely accepted that filaggrin (FLG) deficiency contributes to an abnormal barrier function in ichthyosis vulgaris and atopic dermatitis, the pathomechanism of how FLG deficiency provokes a barrier abnormality in humans is unknown. We report here that the presence of FLG mutations in Caucasians predicts dose-dependent alterations in epidermal permeability barrier function. Although FLG is an intracellular protein, the barrier abnormality occurred solely via a paracellular route in affected stratum corneum. Abnormal barrier function correlated with alterations in keratin filament organization (perinuclear retraction), impaired loading of lamellar body contents, followed by nonuniform extracellular distribution of secreted organelle contents, and abnormalities in lamellar bilayer architecture. In addition, we observed reductions in corneodesmosome density and tight junction protein expression. Thus, FLG deficiency provokes alterations in keratinocyte architecture that influence epidermal functions localizing to the extracellular matrix. These results clarify how FLG mutations impair epidermal permeability barrier function.

  5. Exhaled Aerosol Pattern Discloses Lung Structural Abnormality: A Sensitivity Study Using Computational Modeling and Fractal Analysis

    PubMed Central

    Xi, Jinxiang; Si, Xiuhua A.; Kim, JongWon; Mckee, Edward; Lin, En-Bing

    2014-01-01

    Background Exhaled aerosol patterns, also called aerosol fingerprints, provide clues to the health of the lung and can be used to detect disease-modified airway structures. The key is how to decode the exhaled aerosol fingerprints and retrieve the lung structural information for a non-invasive identification of respiratory diseases. Objective and Methods In this study, a CFD-fractal analysis method was developed to quantify exhaled aerosol fingerprints and applied it to one benign and three malign conditions: a tracheal carina tumor, a bronchial tumor, and asthma. Respirations of tracer aerosols of 1 µm at a flow rate of 30 L/min were simulated, with exhaled distributions recorded at the mouth. Large eddy simulations and a Lagrangian tracking approach were used to simulate respiratory airflows and aerosol dynamics. Aerosol morphometric measures such as concentration disparity, spatial distributions, and fractal analysis were applied to distinguish various exhaled aerosol patterns. Findings Utilizing physiology-based modeling, we demonstrated substantial differences in exhaled aerosol distributions among normal and pathological airways, which were suggestive of the disease location and extent. With fractal analysis, we also demonstrated that exhaled aerosol patterns exhibited fractal behavior in both the entire image and selected regions of interest. Each exhaled aerosol fingerprint exhibited distinct pattern parameters such as spatial probability, fractal dimension, lacunarity, and multifractal spectrum. Furthermore, a correlation of the diseased location and exhaled aerosol spatial distribution was established for asthma. Conclusion Aerosol-fingerprint-based breath tests disclose clues about the site and severity of lung diseases and appear to be sensitive enough to be a practical tool for diagnosis and prognosis of respiratory diseases with structural abnormalities. PMID:25105680

  6. Structural Abnormalities in Childhood Absence Epilepsy: Voxel-Based Analysis Using Diffusion Tensor Imaging

    PubMed Central

    Qiu, Wenchao; Gao, Yuan; Yu, Chuanyong; Miao, Ailiang; Tang, Lu; Huang, Shuyang; Hu, Zheng; Xiang, Jing; Wang, Xiaoshan

    2016-01-01

    Purpose: Childhood absence epilepsy (CAE) is a common syndrome of idiopathic generalized epilepsy. However, little is known about the brain structural changes in this type of epilepsy, especially in the default mode network (DMN) regions. This study aims at using the diffusion tensor imaging (DTI) technique to quantify structural abnormalities of DMN nodes in CAE patients. Method: DTI data were acquired in 14 CAE patients (aged 8.64 ± 2.59 years, seven females and seven males) and 16 age- and sex-matched healthy controls. The data were analyzed using voxel-based analysis (VBA) and statistically compared between patients and controls. Pearson correlation was explored between altered DTI metrics and clinical parameters. The difference of brain volumes between patients and controls were also tested using unpaired t-test. Results: Patients showed significant increase of mean diffusivity (MD) and radial diffusivity (RD) in left medial prefrontal cortex (MPFC), and decrease of fractional anisotropy (FA) in left precuneus and axial diffusivity (AD) in both left MPFC and precuneus. In correlation analysis, MD value from left MPFC was positively associated with duration of epilepsy. Neither the disease duration nor the seizure frequency showed significant correlation with FA values. Between-group comparison of brain volumes got no significant difference. Conclusion: The findings indicate that structural impairments exist in DMN regions in children suffering from absence epilepsy and MD values positively correlate with epilepsy duration. This may contribute to understanding the pathological mechanisms of chronic neurological deficits and promote the development of new therapies for this disorder. PMID:27733824

  7. Delineation of candidate genes responsible for structural brain abnormalities in patients with terminal deletions of chromosome 6q27

    PubMed Central

    Peddibhotla, Sirisha; Nagamani, Sandesh CS; Erez, Ayelet; Hunter, Jill V; Holder Jr, J Lloyd; Carlin, Mary E; Bader, Patricia I; Perras, Helene MF; Allanson, Judith E; Newman, Leslie; Simpson, Gayle; Immken, LaDonna; Powell, Erin; Mohanty, Aaron; Kang, Sung-Hae L; Stankiewicz, Pawel; Bacino, Carlos A; Bi, Weimin; Patel, Ankita; Cheung, Sau W

    2015-01-01

    Patients with terminal deletions of chromosome 6q present with structural brain abnormalities including agenesis of corpus callosum, hydrocephalus, periventricular nodular heterotopia, and cerebellar malformations. The 6q27 region harbors genes that are important for the normal development of brain and delineation of a critical deletion region for structural brain abnormalities may lead to a better genotype–phenotype correlation. We conducted a detailed clinical and molecular characterization of seven unrelated patients with deletions involving chromosome 6q27. All patients had structural brain abnormalities. Using array comparative genomic hybridization, we mapped the size, extent, and genomic content of these deletions. The smallest region of overlap spans 1.7 Mb and contains DLL1, THBS2, PHF10, and C6orf70 (ERMARD) that are plausible candidates for the causation of structural brain abnormalities. Our study reiterates the importance of 6q27 region in normal development of brain and helps identify putative genes in causation of structural brain anomalies. PMID:24736736

  8. Delineation of candidate genes responsible for structural brain abnormalities in patients with terminal deletions of chromosome 6q27.

    PubMed

    Peddibhotla, Sirisha; Nagamani, Sandesh C S; Erez, Ayelet; Hunter, Jill V; Holder, J Lloyd; Carlin, Mary E; Bader, Patricia I; Perras, Helene M F; Allanson, Judith E; Newman, Leslie; Simpson, Gayle; Immken, LaDonna; Powell, Erin; Mohanty, Aaron; Kang, Sung-Hae L; Stankiewicz, Pawel; Bacino, Carlos A; Bi, Weimin; Patel, Ankita; Cheung, Sau W

    2015-01-01

    Patients with terminal deletions of chromosome 6q present with structural brain abnormalities including agenesis of corpus callosum, hydrocephalus, periventricular nodular heterotopia, and cerebellar malformations. The 6q27 region harbors genes that are important for the normal development of brain and delineation of a critical deletion region for structural brain abnormalities may lead to a better genotype-phenotype correlation. We conducted a detailed clinical and molecular characterization of seven unrelated patients with deletions involving chromosome 6q27. All patients had structural brain abnormalities. Using array comparative genomic hybridization, we mapped the size, extent, and genomic content of these deletions. The smallest region of overlap spans 1.7 Mb and contains DLL1, THBS2, PHF10, and C6orf70 (ERMARD) that are plausible candidates for the causation of structural brain abnormalities. Our study reiterates the importance of 6q27 region in normal development of brain and helps identify putative genes in causation of structural brain anomalies.

  9. MRI findings in throwing shoulders: abnormalities in professional handball players.

    PubMed

    Jost, Bernhard; Zumstein, Matthias; Pfirrmann, Christian W A; Zanetti, Marco; Gerber, Christian

    2005-05-01

    Shoulders of throwing athletes are highly stressed joints and likely to have more structural abnormalities seen on magnetic resonance imaging scans. Prevalence and type of structural abnormalities, especially abnormalities of the rotator cuff tendons and the superolateral humeral head, and correlation of magnetic resonance imaging findings with symptoms and clinical tests, are not well known. Throwing and nonthrowing (symptomatic and asymptomatic) shoulders of 30 fully competitive professional handball players and 20 dominant shoulders of randomly selected volunteers were evaluated for comparison clinically and with magnetic resonance imaging. An average of seven abnormal magnetic resonance imaging findings was observed in the throwing shoulders; more than in the nonthrowing and the control shoulders. Although 93% of the throwing shoulders had abnormal magnetic resonance imaging findings, only 37% were symptomatic. Partial rotator cuff tears and mainly superolateral osteochondral defects of the humeral head were identified as typical throwing lesions. Symptoms correlated poorly with abnormalities seen on magnetic resonance imaging scans and findings from clinical tests. This suggests that the evaluation of an athlete's throwing shoulder should be done very thoroughly and should not be based mainly on abnormalities seen on magnetic resonance imaging scans.

  10. Neurological abnormalities and neurocognitive functions in healthy elder people: A structural equation modeling analysis

    PubMed Central

    2011-01-01

    Background/Aims Neurological abnormalities have been reported in normal aging population. However, most of them were limited to extrapyramidal signs and soft signs such as motor coordination and sensory integration have received much less attention. Very little is known about the relationship between neurological soft signs and neurocognitive function in healthy elder people. The current study aimed to examine the underlying relationships between neurological soft signs and neurocognition in a group of healthy elderly. Methods One hundred and eighty healthy elderly participated in the current study. Neurological soft signs were evaluated with the subscales of Cambridge Neurological Inventory. A set of neurocognitive tests was also administered to all the participants. Structural equation modeling was adopted to examine the underlying relationship between neurological soft signs and neurocognition. Results No significant differences were found between the male and female elder people in neurocognitive function performances and neurological soft signs. The model fitted well in the elderly and indicated the moderate associations between neurological soft signs and neurocognition, specifically verbal memory, visual memory and working memory. Conclusions The neurological soft signs are more or less statistically equivalent to capture the similar information done by conventional neurocognitive function tests in the elderly. The implication of these findings may serve as a potential neurological marker for the early detection of pathological aging diseases or related mental status such as mild cognitive impairment and Alzheimer's disease. PMID:21827719

  11. Microbial community structure and function during abnormal curve development of substrate-induced respiration measurements.

    PubMed

    Bartling, Johanna; Kotzerke, Anja; Mai, Maike; Esperschütz, Jürgen; Buegger, Franz; Schloter, Michael; Wilke, Berndt-Michael

    2009-12-01

    Soil respiration measurements are an established method to test the abundance, activity and vitality of the soil microorganisms. However, abnormal progressions of soil respiration curves impede a clear interpretation of the data. The aim of this study was to investigate the changes in the microbial structure during the formation of phenomena like double peaks and terraces by analysis of the PLFA composition (phospholipid fatty acid composition). Moreover, 13C labeled glucose was used as substrate; therefore it was possible to measure delta13C values both within the PLFA fraction as well as within the carbon dioxide evolved during respiration. As contaminants trinitrotoluene, cycloheximide, and hexadecane were used. The results showed that the appearance of double peaks was mainly related to the growth of fungi with the marker 18:2delta9,12 due to a toxic effect of trinitrotoluene and cycloheximide. In contrast, the phenomenon of terrace formation was related to the utilization of hexadecane as a carbon source mainly by bacteria.

  12. [Structural magnetic resonance imaging in epilepsy].

    PubMed

    Álvarez-Linera Prado, J

    2012-01-01

    Magnetic resonance imaging is the main structural imaging in epilepsy. In patients with focal seizures, detection (and characterization) of a structural lesion consistent with electroclinical data allows therapeutic decisions without having to resort to other more expensive or invasive diagnostic procedures. The identification of some lesions may provide prognostic value, as in the case of Mesial Temporal Sclerosis (MTS) or may contribute to genetic counseling, as in the case of some Malformations of Cortical Development (MCD). The aim of this paper is to review the current state of structural MRI techniques, propose a basic protocol of epilepsy and mention the indications for structural MRI. Also, review the semiology of the main causes of epilepsy, with emphasis on MTS and MCD, by its highest frequency and by the special impact that MRI has shown in dealing with these entities.

  13. Cross-Sectional and Longitudinal Abnormalities in Brain Structure in Children with Severe Mood Dysregulation or Bipolar Disorder

    ERIC Educational Resources Information Center

    Adleman, Nancy E.; Fromm, Stephen J.; Razdan, Varun; Kayser, Reilly; Dickstein, Daniel P.; Brotman, Melissa A.; Pine, Daniel S.; Leibenluft, Ellen

    2012-01-01

    Background: There is debate as to whether chronic irritability (operationalized as severe mood dysregulation, SMD) is a developmental form of bipolar disorder (BD). Although structural brain abnormalities in BD have been demonstrated, no study compares neuroanatomy among SMD, BD, and healthy volunteers (HV) either cross-sectionally or over time.…

  14. Are structural brain abnormalities associated with suicidal behavior in patients with psychotic disorders?

    PubMed

    Giakoumatos, Christoforos I; Tandon, Neeraj; Shah, Jai; Mathew, Ian T; Brady, Roscoe O; Clementz, Brett A; Pearlson, Godfrey D; Thaker, Gunvant K; Tamminga, Carol A; Sweeney, John A; Keshavan, Matcheri S

    2013-10-01

    Suicide represents a major health problem world-wide. Nevertheless, the understanding of the neurobiological underpinnings of suicidal behavior remains far from complete. We compared suicide attempters to non-attempters, and high vs. low lethality attempters, to identify brain regions associated with suicidal behavior in patients with psychotic disorders. 489 individuals with schizophrenia, schizoaffective disorder, or psychotic bipolar disorder I and 262 healthy controls enrolled in the B-SNIP study were studied. Groups were compared by attempt history and the highest medical lethality of previous suicide attempts. 97 patients had a history of a high lethality attempt, 51 of a low lethality attempt and 341 had no attempt history. Gray matter volumes were obtained from 3T structural MRI scans using FreeSurfer. ANCOVAs were used to examine differences between groups, followed by Hochberg multiple comparison correction. Compared to non-attempters, attempters had significantly less gray matter volume in bilateral inferior temporal and superior temporal cortices, left superior parietal, thalamus and supramarginal regions, right insula, superior frontal and rostral middle frontal regions. Among attempters, a history of high lethality attempts was associated with significantly smaller volumes in the left lingual gyrus and right cuneus. Compared to non-attempters, low lethality attempters had significant decreases in the left supramarginal gyrus, thalamus and the right insula. Structural brain abnormalities may distinguish suicide attempters from non-attempters and high from low lethality attempters among individuals with psychotic disorders. Regions in which differences were observed are part of neural circuitries that mediate inhibition, impulsivity and emotion, visceral, visual and auditory perception.

  15. Abnormal spontaneous regional brain activity in primary insomnia: a resting-state functional magnetic resonance imaging study

    PubMed Central

    Li, Chao; Ma, Xiaofen; Dong, Mengshi; Yin, Yi; Hua, Kelei; Li, Meng; Li, Changhong; Zhan, Wenfeng; Li, Cheng; Jiang, Guihua

    2016-01-01

    Objective Investigating functional specialization is crucial for a complete understanding of the neural mechanisms of primary insomnia (PI). Resting-state functional magnetic resonance imaging (fMRI) is a useful tool to explore the functional specialization of PI. However, only a few studies have focused on the functional specialization of PI using resting-state fMRI and results of these studies were far from consistent. Thus, the current study aimed to investigate functional specialization of PI using resting-state fMRI with amplitude of low frequency fluctuations (ALFFs) algorithm. Methods In this study, 55 PI patients and 44 healthy controls were included. ALFF values were compared between the two groups using two-sample t-test. The relationship of abnormal ALFF values with clinical characteristics and duration of insomnia was investigated using Pearson’s correlation analysis. Results PI patients showed lower ALFF values in the left orbitofrontal cortex/inferior frontal gyrus, right middle frontal gyrus, left inferior parietal lobule, and bilateral cerebellum posterior lobes, while higher ALFF values in the right middle/inferior temporal that extended to the right occipital lobe. In addition, we found that the duration of PI negatively correlated with ALFF values in the left orbitofrontal cortex/inferior frontal gyrus, and the Pittsburgh Sleep Quality Index score negatively correlated with ALFF values in the left inferior parietal lobule. Conclusion The present study added information to limited studies on functional specialization and provided evidence for hyperarousal hypothesis in PI. PMID:27366068

  16. Method of using triaxial magnetic fields for making particle structures

    DOEpatents

    Martin, James E.; Anderson, Robert A.; Williamson, Rodney L.

    2005-01-18

    A method of producing three-dimensional particle structures with enhanced magnetic susceptibility in three dimensions by applying a triaxial energetic field to a magnetic particle suspension and subsequently stabilizing said particle structure. Combinations of direct current and alternating current fields in three dimensions produce particle gel structures, honeycomb structures, and foam-like structures.

  17. Coronal magnetic structure at a solar sector boundary

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.; Svalgaard, L.

    1973-01-01

    The persistent large-scale coronal magnetic structure associated with a sector boundary appears to consist of a magnetic arcade loop structure extending from one solar polar region to the other in approximately the North-South direction. This structure was inferred from computer coronal magnetic field maps for days on which a stable magnetic sector boundary was near central meridian, based on an interplanetary sector boundary observed to recur during much of 1968 and 1969.

  18. Abnormalities of motor function, transcription and cerebellar structure in mouse models of THAP1 dystonia.

    PubMed

    Ruiz, Marta; Perez-Garcia, Georgina; Ortiz-Virumbrales, Maitane; Méneret, Aurelie; Morant, Andrika; Kottwitz, Jessica; Fuchs, Tania; Bonet, Justine; Gonzalez-Alegre, Pedro; Hof, Patrick R; Ozelius, Laurie J; Ehrlich, Michelle E

    2015-12-20

    DYT6 dystonia is caused by mutations in THAP1 [Thanatos-associated (THAP) domain-containing apoptosis-associated protein] and is autosomal dominant and partially penetrant. Like other genetic primary dystonias, DYT6 patients have no characteristic neuropathology, and mechanisms by which mutations in THAP1 cause dystonia are unknown. Thap1 is a zinc-finger transcription factor, and most pathogenic THAP1 mutations are missense and are located in the DNA-binding domain. There are also nonsense mutations, which act as the equivalent of a null allele because they result in the generation of small mRNA species that are likely rapidly degraded via nonsense-mediated decay. The function of Thap1 in neurons is unknown, but there is a unique, neuronal 50-kDa Thap1 species, and Thap1 levels are auto-regulated on the mRNA level. Herein, we present the first characterization of two mouse models of DYT6, including a pathogenic knockin mutation, C54Y and a null mutation. Alterations in motor behaviors, transcription and brain structure are demonstrated. The projection neurons of the deep cerebellar nuclei are especially altered. Abnormalities vary according to genotype, sex, age and/or brain region, but importantly, overlap with those of other dystonia mouse models. These data highlight the similarities and differences in age- and cell-specific effects of a Thap1 mutation, indicating that the pathophysiology of THAP1 mutations should be assayed at multiple ages and neuronal types and support the notion of final common pathways in the pathophysiology of dystonia arising from disparate mutations. PMID:26376866

  19. Abnormalities of motor function, transcription and cerebellar structure in mouse models of THAP1 dystonia.

    PubMed

    Ruiz, Marta; Perez-Garcia, Georgina; Ortiz-Virumbrales, Maitane; Méneret, Aurelie; Morant, Andrika; Kottwitz, Jessica; Fuchs, Tania; Bonet, Justine; Gonzalez-Alegre, Pedro; Hof, Patrick R; Ozelius, Laurie J; Ehrlich, Michelle E

    2015-12-20

    DYT6 dystonia is caused by mutations in THAP1 [Thanatos-associated (THAP) domain-containing apoptosis-associated protein] and is autosomal dominant and partially penetrant. Like other genetic primary dystonias, DYT6 patients have no characteristic neuropathology, and mechanisms by which mutations in THAP1 cause dystonia are unknown. Thap1 is a zinc-finger transcription factor, and most pathogenic THAP1 mutations are missense and are located in the DNA-binding domain. There are also nonsense mutations, which act as the equivalent of a null allele because they result in the generation of small mRNA species that are likely rapidly degraded via nonsense-mediated decay. The function of Thap1 in neurons is unknown, but there is a unique, neuronal 50-kDa Thap1 species, and Thap1 levels are auto-regulated on the mRNA level. Herein, we present the first characterization of two mouse models of DYT6, including a pathogenic knockin mutation, C54Y and a null mutation. Alterations in motor behaviors, transcription and brain structure are demonstrated. The projection neurons of the deep cerebellar nuclei are especially altered. Abnormalities vary according to genotype, sex, age and/or brain region, but importantly, overlap with those of other dystonia mouse models. These data highlight the similarities and differences in age- and cell-specific effects of a Thap1 mutation, indicating that the pathophysiology of THAP1 mutations should be assayed at multiple ages and neuronal types and support the notion of final common pathways in the pathophysiology of dystonia arising from disparate mutations.

  20. Structural magnetism: Experimental studies of the relations between structures and magnetic properties

    NASA Astrophysics Data System (ADS)

    Lin, Tao

    The magnetic properties of transition metals are known to depend strongly upon their crystal structure. One way to artificially control the structure is through the preparation of superlattices, where a metastable phase of one element may be stabilized through epitaxial growth. Many metastable systems achieved exhibit unusual properties. Some newly developed technologies make this study possible. Epitaxial sputtering was established within this decade and it is our primary growth method. X-ray diffraction is still the most important technique in determining crystal structure. Magnetic optical Kerr effect (MOKE) can give lots of important information on magnetic properties such as the coercivity and the saturation Kerr effect. The theory of the X-ray magnetic circular dichroism (XMCD) is quite similar to MOKE except that it uses X-rays instead of visible light. This feature enables XMCD to detect the element specific magnetic properties which play a central role in this study. The studies on Fe/Ni and Fe/Ru multilayers discovered many extraordinary behaviors of Ni and Ru. in their metastable phase. For example, as an important ferromagnetic metal, Ni is found enhanced magnetic moment in bct structure for the first time. The study on the Slater-Pauling curve for the 4d elements is to continue a 70-year construction of Slater-Pauling curve. Benefited from those new techniques, the construction of the Slater- Pauling curve for the 4d elements was accomplished. Metastable phase fct-Fe is of particular interesting because it displays a large variety of structural magnetic properties. It was found in this project that Fe magnetic moment in the [4d alloy/Fe/4d alloy] structure has a strong dependence on the electron interaction between Fe and 4d element. Although there is no solid evidence indicating that the resistance of tunneling junctions with GdN barrier have dependence on external magnetic field, lots of interesting results were still found, such as the relation

  1. Crustal structure interpreted from magnetic anomalies

    NASA Technical Reports Server (NTRS)

    Phillips, Jeffrey D.; Reynolds, Richard L.; Frey, Herbert

    1991-01-01

    This review, discusses publications during the last quadrennium (1987-1990) that used aeromagnetic data, marine magnetic data, satellite magnetic data, and rock magnetic and petrologic data to provide information on the sources of magnetic anomalies. The publications reviewed reflect increased integration of rock magnetic property and petrologic studies with magnetic anomaly interpretation studies, particularly in deep crustal magnetization, exploration for hydrocarbons, and inversion of marine magnetic anomalies. Interpretations of aeromagnetic data featuring image display techniques and using the horizontal gradient method for locating magnetization boundaries became standard.

  2. Molecular structure and motion in zero field magnetic resonance

    SciTech Connect

    Jarvie, T.P.

    1989-10-01

    Zero field magnetic resonance is well suited for the determination of molecular structure and the study of motion in disordered materials. Experiments performed in zero applied magnetic field avoid the anisotropic broadening in high field nuclear magnetic resonance (NMR) experiments. As a result, molecular structure and subtle effects of motion are more readily observed.

  3. Structural brain abnormalities in postural tachycardia syndrome: A VBM-DARTEL study

    PubMed Central

    Umeda, Satoshi; Harrison, Neil A.; Gray, Marcus A.; Mathias, Christopher J.; Critchley, Hugo D.

    2015-01-01

    Postural tachycardia syndrome (PoTS), a form of dysautonomia, is characterized by orthostatic intolerance, and is frequently accompanied by a range of symptoms including palpitations, lightheadedness, clouding of thought, blurred vision, fatigue, anxiety, and depression. Although the estimated prevalence of PoTS is approximately 5–10 times as common as the better-known condition orthostatic hypotension, the neural substrates of the syndrome are poorly characterized. In the present study, we used magnetic resonance imaging (MRI) with voxel-based morphometry (VBM) applying the diffeomorphic anatomical registration through exponentiated lie algebra (DARTEL) procedure to examine variation in regional brain structure associated with PoTS. We recruited 11 patients with established PoTS and 23 age-matched normal controls. Group comparison of gray matter volume revealed diminished gray matter volume within the left anterior insula, right middle frontal gyrus and right cingulate gyrus in the PoTS group. We also observed lower white matter volume beneath the precentral gyrus and paracentral lobule, right pre- and post-central gyrus, paracentral lobule and superior frontal gyrus in PoTS patients. Subsequent ROI analyses revealed significant negative correlations between left insula volume and trait anxiety and depression scores. Together, these findings of structural differences, particularly within insular and cingulate components of the salience network, suggest a link between dysregulated physiological reactions arising from compromised central autonomic control (and interoceptive representation) and increased vulnerability to psychiatric symptoms in PoTS patients. PMID:25852449

  4. Structure, Transport Properties, and Magnetism of Artificially-Structured Materials

    NASA Astrophysics Data System (ADS)

    Xiao, John Q.

    Structural, magnetic, and magneto-transport properties of three different classes of artificially structured materials: (1) multilayers (Fe(110)/Ag(111) and Fe(110)/W(110)), (2) Fe-nitrides, and (3) metallic granular solids (Co/Ag, Co/Cu Fe/Ag and (Ni-Fe)/Ag), prepared by magnetron sputtering are presented. In the multilayers, the structure has been characterized using both low-angle and high-angle x-ray diffraction together with theoretical modeling. The magnetic properties of the Fe/Ag and Fe/W multilayers have been studied when the layer thickness of Fe and the intervening Ag or W layers are systematically varied. In the case of Fe/Ag multilayers, the interfaces are sharp. The Fe magnetic moment slightly increases with decreasing Fe layer thickness. The magnetization shows a B T^{3/2} dependence with very large values of B. In the Fe/W multilayers, there are small intermixed regions of one or two monolayers at the interfaces. The Fe moments within this region are deteriorated, whereas the rest of the Fe moments maintain their bulk values. With reactive sputtering using a mixture of argon and ammonia gases, all stable Fe-nitrides (gamma ^'-Fe_4N, varepsilon-Fe_{2 -3}N, and zeta-Fe _2N) of single phase can be fabricated. The phase diagram of Fe-nitride composition as a function of pressure of NH_3 has been determined. The magnetic properties and the Mossbauer parameters are in excellent agreement with those from the bulk samples. The magneto-transport properties in metallic granular solids, related metastable alloys and in samples with mixed phases, have been extensively studied. We have investigated the magneto-transport properties as a function of the annealing temperature, temperatures, and the magnetic concentration. For the first time, giant magnetoresistance (GMR) has been observed in non-layered but granular solids. We have shown that the GMR is isotropic and is the extra resistivity due to scattering from the non-aligned ferromagnetic entities. This extra

  5. Altered structure of cortical sulci in gilles de la Tourette syndrome: Further support for abnormal brain development.

    PubMed

    Muellner, Julia; Delmaire, Christine; Valabrégue, Romain; Schüpbach, Michael; Mangin, Jean-François; Vidailhet, Marie; Lehéricy, Stéphane; Hartmann, Andreas; Worbe, Yulia

    2015-04-15

    Gilles de la Tourette syndrome is a neurodevelopmental disorder characterized by the presence of motor and vocal tics. We hypothesized that patients with this syndrome would present an aberrant pattern of cortical formation, which could potentially reflect global alterations of brain development. Using 3 Tesla structural neuroimaging, we compared sulcal depth, opening, and length and thickness of sulcal gray matter in 52 adult patients and 52 matched controls. Cortical sulci were automatically reconstructed and identified over the whole brain, using BrainVisa software. We focused on frontal, parietal, and temporal cortical regions, in which abnormal structure and functional activity were identified in previous neuroimaging studies. Partial correlation analysis with age, sex, and treatment as covariables of noninterest was performed amongst relevant clinical and neuroimaging variables in patients. Patients with Gilles de la Tourette syndrome showed lower depth and reduced thickness of gray matter in the pre- and post-central as well as superior, inferior, and internal frontal sulci. In patients with associated obsessive-compulsive disorder, additional structural changes were found in temporal, insular, and olfactory sulci. Crucially, severity of tics and of obsessive-compulsive disorder measured by Yale Global Tic severity scale and Yale-Brown Obsessive-Compulsive scale, respectively, correlated with structural sulcal changes in sensorimotor, temporal, dorsolateral prefrontal, and middle cingulate cortical areas. Patients with Gilles de la Tourette syndrome displayed an abnormal structural pattern of cortical sulci, which correlated with severity of clinical symptoms. Our results provide further evidence of abnormal brain development in GTS.

  6. Abnormal structure of fear circuitry in pediatric post-traumatic stress disorder.

    PubMed

    Keding, Taylor J; Herringa, Ryan J

    2015-02-01

    Structural brain studies of adult post-traumatic stress disorder (PTSD) show reduced gray matter volume (GMV) in fear regulatory areas including the ventromedial prefrontal cortex (vmPFC) and hippocampus. Surprisingly, neither finding has been reported in pediatric PTSD. One possibility is that they represent age-dependent effects that are not fully apparent until adulthood. In addition, lower-resolution MRI and image processing in prior studies may have limited detection of such differences. Here we examine fear circuitry GMV, including age-related differences, using higher-resolution MRI in pediatric PTSD vs healthy youth. In a cross-sectional design, 3 T anatomical brain MRI was acquired in 27 medication-free youth with PTSD and 27 healthy non-traumatized youth of comparable age, sex, and IQ. Voxel-based morphometry was used to compare GMV in a priori regions including the medial prefrontal cortex and amygdala/hippocampus. Compared with healthy youth, PTSD youth had reduced GMV but no age-related differences in anterior vmPFC (BA 10/11, Z=4.5), which inversely correlated with PTSD duration. In contrast, although there was no overall group difference in hippocampal volume, a group × age interaction (Z=3.6) was present in the right anterior hippocampus. Here, age positively predicted hippocampal volume in healthy youth but negatively predicted volume in PTSD youth. Within the PTSD group, re-experiencing symptoms inversely correlated with subgenual anterior cingulate cortex (sgACC, Z=3.7) and right anterior hippocampus (Z=3.5) GMV. Pediatric PTSD is associated with abnormal structure of the vmPFC and age-related differences in the hippocampus, regions important in the extinction and contextual gating of fear. Reduced anterior vmPFC volume may confer impaired recovery from illness, consistent with its role in the allocation of attentional resources. In contrast, individual differences in sgACC volume were associated with re-experiencing symptoms, consistent with

  7. Structural analysis of ITER magnet feeders

    SciTech Connect

    Ilyin, Yuri; Gung, Chen-Yu; Bauer, Pierre; Chen, Yonghua; Jong, Cornelis; Devred, Arnaud; Mitchell, Neil; Lorriere, Philippe; Farek, Jaromir; Nannini, Matthieu

    2012-06-15

    This paper summarizes the results of the static structural analyses, which were conducted in support of the ITER magnet feeder design with the aim of validating certain components against the structural design criteria. While almost every feeder has unique features, they all share many common constructional elements and the same functional specifications. The analysis approach to assess the load conditions and stresses that have driven the design is equivalent for all feeders, except for particularities that needed to be modeled in each case. The mechanical analysis of the feeders follows the sub-modeling approach: the results of the global mechanical model of a feeder assembly are used as input for the detailed models of the feeder' sub-assemblies or single components. Examples of such approach, including the load conditions, stress assessment criteria and solutions for the most critical components, are discussed. It has been concluded that the feeder system is safe in the referential operation scenarios. (authors)

  8. Influence Of Nanoparticles Diameter On Structural Properties Of Magnetic Fluid In Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kúdelčík, Jozef; Bury, Peter; Hardoň, Štefan; Kopčanský, Peter; Timko, Milan

    2015-07-01

    The properties of magnetic fluids depend on the nanoparticle diameter, their concentration and the carrier liquid. The structural changes in magnetic fluids with different nanoparticle diameter based on transformer oils TECHNOL and MOGUL under the effect of a magnetic field and temperature were studied by acoustic spectroscopy. At a linear and jump changes of the magnetic field at various temperatures a continuous change was observed of acoustic attenuation caused by aggregation of the magnetic nanoparticles to structures. From the anisotropy of acoustic attenuation and using the Taketomi theory the basic parameters of the structures are calculated and the impact of nanoparticle diameters on the size of structures is confirmed.

  9. Structuralization induced by the photothermal effect in magnetic fluid film

    NASA Astrophysics Data System (ADS)

    Timko, M.; Kopčanský, P.; Repašan, M.; Koneracká, M.; Hnatič, M.; Džarová, A.; Štelina, J.; Musil, C.; Ayrjan, E.

    2008-05-01

    The structuralization of magnetic particles after illumination was experimentally observed in two types of a magnetic fluid based on mineral oil with the magnetite particles covered by monolayer surfactant and kerosene-based magnetic fluid sterically stabilized by a double layer consisting of oleic acid and dodecylbenzensulphonic acid (DBS). This contribution presents a detailed theoretical description of the thermodiffusion process in magnetic fluids, simulation of the structuralization in magnetic fluid with a negative Soret constant, and confirmaton of the negative value of this constant for a kerosene-based magnetic fluid.

  10. Detection of structural and numerical chomosomal abnormalities by ACM-FISH analysis in sperm of oligozoospermic infertility patients

    SciTech Connect

    Schmid, T E; Brinkworth, M H; Hill, F; Sloter, E; Kamischke, A; Marchetti, F; Nieschlag, E; Wyrobek, A J

    2003-11-10

    Modern reproductive technologies are enabling the treatment of infertile men with severe disturbances of spermatogenesis. The possibility of elevated frequencies of genetically and chromosomally defective sperm has become an issue of concern with the increased usage of intracytoplasmic sperm injection (ICSI), which can enable men with severely impaired sperm production to father children. Several papers have been published about aneuploidy in oligozoospermic patients, but relatively little is known about chromosome structural aberrations in the sperm of these patients. We examined sperm from infertile, oligozoospermic individuals for structural and numerical chromosomal abnormalities using a multicolor ACM FISH assay that utilizes DNA probes specific for three regions of chromosome 1 to detect human sperm that carry numerical chromosomal abnormalities plus two categories of structural aberrations: duplications and deletions of 1pter and 1cen, and chromosomal breaks within the 1cen-1q12 region. There was a significant increase in the average frequencies of sperm with duplications and deletions in the infertility patients compared with the healthy concurrent controls. There was also a significantly elevated level of breaks within the 1cen-1q12 region. There was no evidence for an increase in chromosome-1 disomy, or in diploidy. Our data reveal that oligozoospermia is associated with chromosomal structural abnormalities suggesting that, oligozoospermic men carry a higher burden of transmissible, chromosome damage. The findings raise the possibility of elevated levels of transmissible chromosomal defects following ICSI treatment.

  11. Disruption of Ah Receptor Signaling during Mouse Development Leads to Abnormal Cardiac Structure and Function in the Adult

    PubMed Central

    Carreira, Vinicius S.; Fan, Yunxia; Kurita, Hisaka; Wang, Qin; Ko, Chia-I; Naticchioni, Mindi; Jiang, Min; Koch, Sheryl; Zhang, Xiang; Biesiada, Jacek; Medvedovic, Mario; Xia, Ying; Rubinstein, Jack; Puga, Alvaro

    2015-01-01

    The Developmental Origins of Health and Disease (DOHaD) Theory proposes that the environment encountered during fetal life and infancy permanently shapes tissue physiology and homeostasis such that damage resulting from maternal stress, poor nutrition or exposure to environmental agents may be at the heart of adult onset disease. Interference with endogenous developmental functions of the aryl hydrocarbon receptor (AHR), either by gene ablation or by exposure in utero to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent AHR ligand, causes structural, molecular and functional cardiac abnormalities and altered heart physiology in mouse embryos. To test if embryonic effects progress into an adult phenotype, we investigated whether Ahr ablation or TCDD exposure in utero resulted in cardiac abnormalities in adult mice long after removal of the agent. Ten-months old adult Ahr-/- and in utero TCDD-exposed Ahr+/+ mice showed sexually dimorphic abnormal cardiovascular phenotypes characterized by echocardiographic findings of hypertrophy, ventricular dilation and increased heart weight, resting heart rate and systolic and mean blood pressure, and decreased exercise tolerance. Underlying these effects, genes in signaling networks related to cardiac hypertrophy and mitochondrial function were differentially expressed. Cardiac dysfunction in mouse embryos resulting from AHR signaling disruption seems to progress into abnormal cardiac structure and function that predispose adults to cardiac disease, but while embryonic dysfunction is equally robust in males and females, the adult abnormalities are more prevalent in females, with the highest severity in Ahr-/- females. The findings reported here underscore the conclusion that AHR signaling in the developing heart is one potential target of environmental factors associated with cardiovascular disease. PMID:26555816

  12. Mapping the magnetic and crystal structure in cobalt nanowires

    SciTech Connect

    Cantu-Valle, Jesus; Betancourt, Israel; Sanchez, John E.; Ruiz-Zepeda, Francisco; Mendoza-Santoyo, Fernando; Ponce, Arturo; Maqableh, Mazin M.; Stadler, Bethanie J. H.

    2015-07-14

    Using off-axis electron holography under Lorentz microscopy conditions to experimentally determine the magnetization distribution in individual cobalt (Co) nanowires, and scanning precession-electron diffraction to obtain their crystalline orientation phase map, allowed us to directly visualize with high accuracy the effect of crystallographic texture on the magnetization of nanowires. The influence of grain boundaries and disorientations on the magnetic structure is correlated on the basis of micromagnetic analysis in order to establish the detailed relationship between magnetic and crystalline structure. This approach demonstrates the applicability of the method employed and provides further understanding on the effect of crystalline structure on magnetic properties at the nanometric scale.

  13. Mapping the magnetic and crystal structure in cobalt nanowires

    PubMed Central

    Cantu-Valle, Jesus; Betancourt, Israel; Sanchez, John E.; Ruiz-Zepeda, Francisco; Maqableh, Mazin M.; Mendoza-Santoyo, Fernando; Stadler, Bethanie J. H.; Ponce, Arturo

    2015-01-01

    Using off-axis electron holography under Lorentz microscopy conditions to experimentally determine the magnetization distribution in individual cobalt (Co) nanowires, and scanning precession-electron diffraction to obtain their crystalline orientation phase map, allowed us to directly visualize with high accuracy the effect of crystallographic texture on the magnetization of nanowires. The influence of grain boundaries and disorientations on the magnetic structure is correlated on the basis of micromagnetic analysis in order to establish the detailed relationship between magnetic and crystalline structure. This approach demonstrates the applicability of the method employed and provides further understanding on the effect of crystalline structure on magnetic properties at the nanometric scale. PMID:26221057

  14. Hard magnetism in structurally engineered silica nanocomposite.

    PubMed

    Song, Hyon-Min; Zink, Jeffrey I

    2016-09-21

    Creation of structural complexity by simple experimental control will be an attractive approach for the preparation of nanomaterials, as a classical bottom-up method is supplemented by a more efficient and more direct artificial engineering method. In this study, structural manipulation of MCM-41 type mesoporous silica is investigated by generating and imbedding hard magnetic CoFe2O4 nanoparticles into mesoporous silica. Depending on the heating rate and target temperature, mesoporous silica undergoes a transformation in shape to form hollow silica, framed silica with interior voids, or melted silica with intact mesostructures. Magnetism is governed by the major CoFe2O4 phase, and it is affected by antiferromagnetic hematite (α-Fe2O3) and olivine-type cobalt silicate (Co2SiO4), as seen in its paramagnetic behavior at the annealing temperature of 430 °C. The early formation of Co2SiO4 than what is usually observed implies the effect of the partial substitution of Fe in the sites of Co. Under slow heating (2.5 °C min(-1)) mesostructures are preserved, but with significantly smaller mesopores (d100 = 1.5 nm). In addition, nonstoichiometric CoxFe1-xO with metal vacancies at 600 °C, and spinel Co3O4 at 700 °C accompany major CoFe2O4. The amorphous nature of silica matrix is thought to contribute significantly to these structurally diverse and rich phases, enabled by off-stoichiometry between Si and O, and accelerated by the diffusion of metal cations into SiO4 polyhedra at an elevated temperature. PMID:27537252

  15. Hard magnetism in structurally engineered silica nanocomposite.

    PubMed

    Song, Hyon-Min; Zink, Jeffrey I

    2016-09-21

    Creation of structural complexity by simple experimental control will be an attractive approach for the preparation of nanomaterials, as a classical bottom-up method is supplemented by a more efficient and more direct artificial engineering method. In this study, structural manipulation of MCM-41 type mesoporous silica is investigated by generating and imbedding hard magnetic CoFe2O4 nanoparticles into mesoporous silica. Depending on the heating rate and target temperature, mesoporous silica undergoes a transformation in shape to form hollow silica, framed silica with interior voids, or melted silica with intact mesostructures. Magnetism is governed by the major CoFe2O4 phase, and it is affected by antiferromagnetic hematite (α-Fe2O3) and olivine-type cobalt silicate (Co2SiO4), as seen in its paramagnetic behavior at the annealing temperature of 430 °C. The early formation of Co2SiO4 than what is usually observed implies the effect of the partial substitution of Fe in the sites of Co. Under slow heating (2.5 °C min(-1)) mesostructures are preserved, but with significantly smaller mesopores (d100 = 1.5 nm). In addition, nonstoichiometric CoxFe1-xO with metal vacancies at 600 °C, and spinel Co3O4 at 700 °C accompany major CoFe2O4. The amorphous nature of silica matrix is thought to contribute significantly to these structurally diverse and rich phases, enabled by off-stoichiometry between Si and O, and accelerated by the diffusion of metal cations into SiO4 polyhedra at an elevated temperature.

  16. Computational and experimental investigations of magnetic domain structures in patterned magnetic thin films

    NASA Astrophysics Data System (ADS)

    Li, Yulan; Xu, Ke; Hu, Shenyang; Suter, Jon; Schreiber, Daniel K.; Ramuhalli, Pradeep; Johnson, Bradley R.; McCloy, John

    2015-08-01

    The use of nondestructive magnetic signatures for continuous monitoring of the degradation of structural materials in nuclear reactors is a promising yet challenging application for advanced functional materials behavior modeling and measurement. In this work, a numerical model, which is based on the Landau-Lifshitz-Gilbert equation of magnetization dynamics and the phase field approach, was developed to study the impact of defects such as nonmagnetic precipitates and/or voids, free surfaces and crystal orientation on magnetic domain structures and magnetic responses in magnetic materials, with the goal of exploring the correlation between microstructures and magnetic signatures. To validate the model, single crystal iron thin films (~240 nm thickness) were grown on MgO substrates and a focused ion beam was used to pattern micrometer-scale specimens with different geometries. Magnetic force microscopy (MFM) was used to measure magnetic domain structure and its field-dependence. Numerical simulations were constructed with the same geometry as the patterned specimens and under similar applied magnetic field conditions as tested by MFM. The results from simulations and experiments show that 1) magnetic domain structures strongly depend on the film geometry and the external applied field and 2) the predicted magnetic domain structures from the simulations agree quantitatively with those measured by MFM. The results demonstrate the capability of the developed model, used together with key experiments, for improving the understanding of the signal physics in magnetic sensing, thereby providing guidance to the development of advanced nondestructive magnetic techniques.

  17. Abnormal Subcortical Components of the Corticostriatal System in Young Adults with DLI: A Combined Structural MRI and DTI Study

    PubMed Central

    Lee, Joanna C.; Nopoulos, Peggy C.; Tomblin, J. Bruce

    2013-01-01

    Developmental Language Impairment (DLI) is a neurodevelopmental disorder affecting 12% to 14% of the school-age children in the United States. While substantial studies have shown a wide range of linguistic and non-linguistic difficulty in individuals with DLI, very little is known about the neuroanatomical mechanisms underlying this disorder. In the current study, we examined the subcortical components of the corticostriatal system in young adults with DLI, including the caudate nucleus, the putamen, the nucleus accumbens, the globus pallidus, and the thalamus. Additionally, the four cerebral lobes and the hippocampus were also comprised for an exploratory analysis. We used conventional magnetic resonance imaging (MRI) to measure regional brain volumes, as well as diffusion tensor imaging (DTI) to assess water diffusion anisotropy as quantified by fractional anisotropy (FA). Two groups of participants, one with DLI (n=12) and the other without ( n=12), were recruited from a prior behavioral study, and all were matched on age, gender, and handedness. Volumetric analyses revealed region-specific abnormalities in individuals with DLI, showing pathological enlargement bilaterally in the putamen and the nucleus accumbens, and unilaterally in the right globus pallidus after the intracranial volumes were controlled. Regarding the DTI findings, the DLI group showed decreased FA values in the globus pallidus and the thalamus but these significant differences disappeared after controlling for the whole-brain FA value, indicating that microstructural abnormality is diffuse and affects other regions of the brain. Taken together, these results suggest region-specific corticostriatal abnormalities in DLI at the macrostructural level, but corticostriatal abnormalities at the microstructural level may be a part of a diffuse pattern of brain development. Future work is suggested to investigate the relationship between corticostriatal connectivity and individual differences in

  18. Magnetic control of waveguide modes of Bragg structures

    NASA Astrophysics Data System (ADS)

    Sylgacheva, D. A.; Khokhlov, N. E.; Kalish, A. N.; Belotelov, V. I.

    2016-05-01

    We present the study of the waveguide modes of one-dimensional magnetic photonic crystals with in-plane-magnetized layers. There is a magneto-optical effect of nonreciprocity for the TM-modes propagating along the layers perpendicularly to the magnetization. Due to the non-reciprocity the phase velocity of the modes changes with magnetization reversal. Comparison of the effect in the non-magnetic photonic crystal with additional magnetic layer on top and a magnetophotonic crystal with altering magnetic layers shows that the effect is greater in the first case due to the higher asymmetry of the claddings of the magnetic layer. This effect is important for the light modulation with external magnetic field in waveguide structures and may be used for design of novel types of the magneto-optical devices, sensors of magnetic field or biosensors.

  19. On the size, structure, and strength of the small-scale solar magnetic field

    NASA Technical Reports Server (NTRS)

    Ramsey, H. E.; Schoolman, S. A.; Title, A. M.

    1977-01-01

    High-resolution magnetograms place an upper limit of 0.33 arcsec on the smallest magnetic-field structures. These magnetograms show that the active-region field is organized into roughly cellular patterns 2-3 arcsec in diameter and that the field structures occur in the centers of 'abnormal' granules. Comparison of these data and other magnetograms with high signal-to-noise ratio indicates that there exists another component of the field that is diffuse on the scale of an arc second and has a maximum strength of less than 500 gauss.

  20. Bias structure to efficiently package a magnetic bubble domain device

    NASA Technical Reports Server (NTRS)

    Chen, Thomas T. (Inventor)

    1978-01-01

    A single, compact bias structure to efficiently package a plurality of magnetic bubble domain device chips having different bias requirements. The vertical magnetic field distribution within the bias structure air gap is selectively controlled by a magnetically soft field adjusting assembly suitably attached within the bias structure. The size and configuration of the field adjusting assembly tailors local field variations within the air gap to correspond with the bias requirements of the bubble domain chips disposed therein.

  1. Magnetic sensor for building structural vibrations.

    PubMed

    García, Alfonso; Morón, Carlos; Tremps, Enrique

    2014-01-01

    This paper shows a new displacement-to-frequency transducer based on the variation of a coil inductance when a magnetic core is partially or completely inserted inside. This transducer is based on a Colpitts oscillator due its low manufacturing price, behavior and immunity to noise. A tank circuit with a configuration in parallel was used because it can be employed at lower frequencies and it enables it to make a direct analysis. The sensor has a dynamic range equal to the length of the coil. The cores can exchange sensors (coils with its ferromagnetic core) using the same electronic measuring system. In this way, with only an electronic circuit, the core sensor determines the measurement range. The obtained resolution is higher than 1/100,000, and the sensor also allows the measurement and knowing in real time the effect of vibration, thermal expansion, referred overload movements, etc.., that can occur in the structural elements of a building. PMID:24504104

  2. Magnetic Sensor for Building Structural Vibrations

    PubMed Central

    García, Alfonso; Morón, Carlos; Tremps, Enrique

    2014-01-01

    This paper shows a new displacement-to-frequency transducer based on the variation of a coil inductance when a magnetic core is partially or completely inserted inside. This transducer is based on a Colpitts oscillator due its low manufacturing price, behavior and immunity to noise. A tank circuit with a configuration in parallel was used because it can be employed at lower frequencies and it enables it to make a direct analysis. The sensor has a dynamic range equal to the length of the coil. The cores can exchange sensors (coils with its ferromagnetic core) using the same electronic measuring system. In this way, with only an electronic circuit, the core sensor determines the measurement range. The obtained resolution is higher than 1/100,000, and the sensor also allows the measurement and knowing in real time the effect of vibration, thermal expansion, referred overload movements, etc.., that can occur in the structural elements of a building. PMID:24504104

  3. Magnetic sensor for building structural vibrations.

    PubMed

    García, Alfonso; Morón, Carlos; Tremps, Enrique

    2014-02-05

    This paper shows a new displacement-to-frequency transducer based on the variation of a coil inductance when a magnetic core is partially or completely inserted inside. This transducer is based on a Colpitts oscillator due its low manufacturing price, behavior and immunity to noise. A tank circuit with a configuration in parallel was used because it can be employed at lower frequencies and it enables it to make a direct analysis. The sensor has a dynamic range equal to the length of the coil. The cores can exchange sensors (coils with its ferromagnetic core) using the same electronic measuring system. In this way, with only an electronic circuit, the core sensor determines the measurement range. The obtained resolution is higher than 1/100,000, and the sensor also allows the measurement and knowing in real time the effect of vibration, thermal expansion, referred overload movements, etc.., that can occur in the structural elements of a building.

  4. Solar Multiple Eruptions from a Confined Magnetic Structure

    NASA Astrophysics Data System (ADS)

    Lee, Jeongwoo; Liu, Chang; Jing, Ju; Chae, Jongchul

    2016-09-01

    How eruption can recur from a confined magnetic structure is discussed based on the Solar Dynamics Observatory observations of the NOAA active region 11444, which produced three eruptions within 1.5 hr on 2012 March 27. The active region (AR) had the positive-polarity magnetic fields in the center surrounded by the negative-polarity fields around. Since such a distribution of magnetic polarity tends to form a dome-like magnetic fan structure confined over the AR, the multiple eruptions were puzzling. Our investigation reveals that this event exhibits several properties distinct from other eruptions associated with magnetic fan structures: (i) a long filament encircling the AR was present before the eruptions; (ii) expansion of the open-closed boundary (OCB) of the field lines after each eruption was suggestive of the growing fan-dome structure, and (iii) the ribbons inside the closed magnetic polarity inversion line evolved in response to the expanding OCB. It thus appears that in spite of multiple eruptions the fan-dome structure remained undamaged, and the closing back field lines after each eruption rather reinforced the fan-dome structure. We argue that the multiple eruptions could occur in this AR in spite of its confined magnetic structure because the filament encircling the AR was adequate for slipping through the magnetic separatrix to minimize the damage to its overlying fan-dome structure. The result of this study provides a new insight into the productivity of eruptions from a confined magnetic structure.

  5. Structural and Perfusion Abnormalities of Brain on MRI and Technetium-99m-ECD SPECT in Children With Cerebral Palsy: A Comparative Study.

    PubMed

    Rana, Kamer Singh; Narwal, Varun; Chauhan, Lokesh; Singh, Giriraj; Sharma, Monica; Chauhan, Suneel

    2016-04-01

    Cerebral palsy has traditionally been associated with hypoxic ischemic brain damage. This study was undertaken to demonstrate structural and perfusion brain abnormalities. Fifty-six children diagnosed clinically as having cerebral palsy were studied between 1 to 14 years of age and were subjected to 3 Tesla magnetic resonance imaging (MRI). Brain and Technetium-99m-ECD brain single-photon emission computed tomography (SPECT) scan. Male to female ratio was 1.8:1 with a mean age of 4.16 ± 2.274 years. Spastic cerebral palsy was the most common type, observed in 91%. Birth asphyxia was the most common etiology (69.6%). White matter changes (73.2%) such as periventricular leukomalacia and corpus callosal thinning were the most common findings on MRI. On SPECT all cases except one revealed perfusion impairments in different regions of brain. MRI is more sensitive in detecting white matter changes, whereas SPECT is better in detecting cortical and subcortical gray matter abnormalities of perfusion.

  6. Structural and Perfusion Abnormalities of Brain on MRI and Technetium-99m-ECD SPECT in Children With Cerebral Palsy: A Comparative Study.

    PubMed

    Rana, Kamer Singh; Narwal, Varun; Chauhan, Lokesh; Singh, Giriraj; Sharma, Monica; Chauhan, Suneel

    2016-04-01

    Cerebral palsy has traditionally been associated with hypoxic ischemic brain damage. This study was undertaken to demonstrate structural and perfusion brain abnormalities. Fifty-six children diagnosed clinically as having cerebral palsy were studied between 1 to 14 years of age and were subjected to 3 Tesla magnetic resonance imaging (MRI). Brain and Technetium-99m-ECD brain single-photon emission computed tomography (SPECT) scan. Male to female ratio was 1.8:1 with a mean age of 4.16 ± 2.274 years. Spastic cerebral palsy was the most common type, observed in 91%. Birth asphyxia was the most common etiology (69.6%). White matter changes (73.2%) such as periventricular leukomalacia and corpus callosal thinning were the most common findings on MRI. On SPECT all cases except one revealed perfusion impairments in different regions of brain. MRI is more sensitive in detecting white matter changes, whereas SPECT is better in detecting cortical and subcortical gray matter abnormalities of perfusion. PMID:26353878

  7. Photographic observation of magnetic domain structure with three-dimensional local magnetization direction

    NASA Astrophysics Data System (ADS)

    Meguro, Sakae; Akahane, Koichi; Saito, Shin

    2016-07-01

    The direction of magnetization of a magnetic material is possibly oriented three-dimensionally because of the presence of magnetic anisotropy field, self-demagnetizing field, and stray field. Therefore, the three-dimensional detection of the direction of magnetization is required. The method of magnetic domain observation by photographic imaging utilizing the Kerr effect is widely used. If the perpendicular magnetization components exist, there is a problem that obliquely incident light has superimposed longitudinal Kerr and polar Kerr effects. To perform the three-dimensional detection of magnetization direction, it is necessary to eliminate the influence of the polar Kerr effect from the Kerr effect of obliquely incident light. We report the photographic observation of the magnetic domain structure and the detection of the three-dimensional local magnetization direction using the Kerr effect, applying only an in-plane saturation magnetic field.

  8. Magnetic Field Sensor Using Polymer MEMS Structures for Detection of Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Oldham, Bradley E.

    This thesis covers the development of a magnetic sensor for application with brain computer interfacing for the detection of motor imagery evoked potentials. For this application, the feasibility of a resonance magnetic cantilever based sensor is investigated via: numerical analysis for feasibility, multilayer structure for layer integration verification, and finally flexible magnetic material characterization for sensing element consideration. The flexible magnetic material that is considered in this thesis is made by the embedding of hard rare earth magnetic (Nd2Fe14B) particles into polydimethylsiloxane (PDMS) and provides a micro-mouldable material with hard magnetic properties. This material provides a couple advantages for design of a small magnetic sensor as it is scalable while being made of a rugged polymer. Additionally, this magnetic material exhibits magnetic rheological properties when exposed to a static magnetic field. While there is additional work needed to complete the sensor design, this thesis shows the feasibility of this design.

  9. Small-molecule structure correctors target abnormal protein structure and function: structure corrector rescue of apolipoprotein E4-associated neuropathology.

    PubMed

    Mahley, Robert W; Huang, Yadong

    2012-11-01

    An attractive strategy to treat proteinopathies (diseases caused by malformed or misfolded proteins) is to restore protein function by inducing proper three-dimensional structure. We hypothesized that this approach would be effective in reversing the detrimental effects of apolipoprotein (apo) E4, the major allele that significantly increases the risk of developing Alzheimer's disease and other neurodegenerative disorders. ApoE4's detrimental effects result from its altered protein conformation ("domain interaction"), making it highly susceptible to proteolytic cleavage and the generation of neurotoxic fragments. Here, we review apoE structure and function and how apoE4 causes neurotoxicity, and describe the identification of potent small-molecule-based "structure correctors" that induce proper apoE4 folding. SAR studies identified a series of small molecules that significantly reduced apoE4's neurotoxic effects in cultured neurons and a series that reduced apoE4 fragment levels in vivo, providing proof-of-concept for our approach. Structure-corrector-based therapies could prove to be highly effective for the treatment of many protein-misfolding diseases.

  10. Abnormal Cortical Plasticity in Youth with Autism Spectrum Disorder: A Transcranial Magnetic Stimulation Case–Control Pilot Study

    PubMed Central

    Gilbert, Donald L.; Erickson, Craig A.; Horn, Paul S.; Shaffer, Rebecca C.; Wink, Logan K.; Laue, Cameron S.; Wu, Steve W.

    2016-01-01

    Abstract Objective: This case–control study investigated the use of a low-intensity repetitive transcranial magnetic stimulation (rTMS) protocol to measure motor cortex (M1) plasticity in youth with autism spectrum disorder (ASD) compared with typically developing children (TDC). We hypothesized that impairments in long-term potentiation-like properties represent a neurophysiological biomarker of abnormal cortical function in ASD. Methods: We studied youth with ASD aged 11–18 years and matched controls (TDC). Intermittent theta burst stimulation (iTBS) was delivered to the dominant M1 at an intensity of 70% of resting motor threshold. Suprathreshold single-pulse TMS was performed to compare amplitudes of motor-evoked potentials (MEP) measured from surface electromyography electrodes on a target muscle before (20 pulses) and after (10 pulses/time point) iTBS at predefined timepoints (up to 30 minutes) to measure any potentiation effects. A linear mixed model was used to examine group differences in MEP amplitudes over time following iTBS. Results: Nine youth with ASD (mean age 15.6; 7 males; 6 right-hand dominant) and 9 TDC (mean age 14.5; 5 males; 9 right-hand dominant) participated. All subjects tolerated the procedure well. Both groups had a mean increase in excitability after iTBS for 30 minutes; however, the time course of excitability changes differed (F9,144 = 2.05; p = 0.038). Post-hoc testing identified a significant decrease in amplitude of the ASD group at 20 minutes following iTBS compared with the TDC after correcting for multiple comparisons. Conclusion: In this study, we demonstrate early evidence for a potential physiological biomarker of cortical plasticity in youth with ASD using a rapid low-intensity rTMS protocol with a discriminate measure at 20 minutes following stimulation. The procedure was well tolerated by all 18 participants. Future work will include modification of the protocol to improve the ability to distinguish subtypes of

  11. Positional Magnetic Resonance Imaging for People With Ehlers-Danlos Syndrome or Suspected Craniovertebral or Cervical Spine Abnormalities: An Evidence-Based Analysis

    PubMed Central

    2015-01-01

    Background Ehlers-Danlos syndrome (EDS) is an inherited disorder affecting the connective tissue. EDS can manifest with symptoms attributable to the spine or craniovertebral junction (CVJ). In addition to EDS, numerous congenital, developmental, or acquired disorders can increase ligamentous laxity in the CVJ and cervical spine. Resulting abnormalities can lead to morbidity and serious neurologic complications. Appropriate imaging and diagnosis is needed to determine patient management and need for complex surgery. Some spinal abnormalities cause symptoms or are more pronounced while patients sit, stand, or perform specific movements. Positional magnetic resonance imaging (pMRI) allows imaging of the spine or CVJ with patients in upright, weight-bearing positions and can be combined with dynamic maneuvers, such as flexion, extension, or rotation. Imaging in these positions could allow diagnosticians to better detect spinal or CVJ abnormalities than recumbent MRI or even a combination of other available imaging modalities might allow. Objectives To determine the diagnostic impact and clinical utility of pMRI for the assessment of (a) craniovertebral or spinal abnormalities among people with EDS and (b) major craniovertebral or cervical spine abnormalities among symptomatic people. Data Sources A literature search was performed using Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid Embase, and EBM Reviews, for studies published from January 1, 1998, to September 28, 2014. Review Methods Studies comparing pMRI to recumbent MRI or other available imaging modalities for diagnosis and management of spinal or CVJ abnormalities were reviewed. All studies of spinal or CVJ imaging in people with EDS were included as well as studies among people with suspected major CVJ or cervical spine abnormalities (cervical or craniovertebral spine instability, basilar invagination, cranial settling, cervical stenosis, spinal cord compression, Chiari

  12. Design and construction of a periodic magnetic structure of SmCo{sub 5} magnets

    SciTech Connect

    Migliano, A.C.C.; Stopa, C.R.S.; Cardoso, J.R.; Zgainski, F.X.; Coulomb, J.L.

    1997-03-01

    A SmCo{sub 5} permanent magnet periodic structure was developed to generate a sinusoidal space-varying magnetic field. This device was designed to be utilized in the wiggler of a infra-red Free-Electron Laser (IR-FEL). To design the structure, finite-element computer codes that calculate magnetic fields in two and three dimensions were utilized. The results obtained from the computer simulations and the mechanical design of the built structure are presented.

  13. A permalloy zigzag structure based magnetic bio-sensor

    NASA Astrophysics Data System (ADS)

    Ger, Tzong-Rong; Xu, You-Ren; Huang, Hao-Ting; Wei, Zung-Hang

    2012-04-01

    A magnetic fluid consisting of Fe3O4 magnetic nanoparticles is embedded inside cells by intracellular uptake. A micro-fabricated magnetic zigzag-shaped surface structure is studied for use as a biosensor. We have developed a MOKE magnetometer based methodology to measure the different hysteresis loop signals between cells with and without being placed on zigzag sensors. Adding the magnetic cells on the structure decreases the coercivity from the magneto-optical Kerr effect (MOKE) signal of zigzag magnetic thin films because of the magnetic properties of superparamagnetic nanoparticles. The magnetoresistance measurement observed is that the switching fields of the zigzag structure with magnetic cells are significantly increased compared to the case without cells in the hard axis of the external field applied.

  14. Magnetism and surface structure of atomically controlled ultrathin metal films.

    SciTech Connect

    Shiratsuchi, Yu.; Yamamoto, M.; Bader, S. D.; Materials Science Division; Osaka Univ.

    2007-01-01

    We review the correlation of magnetism and surface structure in ultrathin metal films, including the tailoring of novel magnetic properties using atomic scale control of the nanostructure. We provide an overview of modern fabrication and characterization techniques used to create and explore these fascinating materials, and highlight important phenomena of interest. We also discuss techniques that control and characterize both the magnetic and structural properties on an atomic scale. Recent advances in the development and applications of these techniques allow nanomagnetism to be investigated in an unprecedented manner. A system cannot necessarily retain a two-dimensional structure as it enters the ultrathin region, but it can transform into a three-dimensional, discontinuous structure due to the Volmer-Weber growth mechanism. This structural transformation can give rise to superparamagnetism. During this evolution, competing factors such as interparticle interactions and the effective magnetic anisotropy govern the magnetic state. These magnetic parameters are influenced by the nanostructure of the film. In particular, controlling the magnetic anisotropy is critical for determining the magnetic properties. Surface effects play especially important roles in influencing both the magnitude and direction of the magnetic anisotropy in ultrathin films. By properly altering the surface structure, the strength and direction of the magnetic anisotropy are controlled via spin-orbit and/or dipole interactions.

  15. Structural chromosomal abnormalities in patients with mental retardation and/or multiple congenital anomalies: a new series of 24 patients.

    PubMed

    Tos, T; Karaman, A; Aksoy, A; Tukun, A

    2012-01-01

    Chromosomal abnormalities are a major cause of mental retardation and/or multiple congenital anomalies (MCA/MR). Screening for these chromosomal imbalances has mainly been done by standard karyotyping. The objective of this study was to report standard chromosome analysis and FISH screening of a series of 24 patients with MCA/MR. Structural chromosomal abnormalities were detected in 24 alterations and included 5 deletions, 2 duplications, 6 unbalanced translocations, 3 inversions, 2 insertions, 3 derivative chromosomes, 2 marker chromosomes and 1 isochromosome. We confirm that a high percentage of MCA/MR cases hitherto considered idiopathic is caused by chromosomal imbalances. We conclude that patients with MCA/MR should be routinely karyotyped.

  16. Oxocuprates: A structural and magnetic zoo

    SciTech Connect

    Ramakrishna, B.L.; Ong, E.W.

    1988-11-15

    We have attempted a magnetostructural correlation for the oxocuprates: Y/sub 2/Cu/sub 2/O/sub 5/, BaCuO/sub 2/, Y/sub 2/BaCuO/sub 5/, and YBa/sub 2/Cu/sub 3/O/sub 6/, all of which are closely related to the new high-T/sub c/ superconductors. It was found that this series of compounds has interesting combinations of ferro- and antiferromagnetic interactions as a consequence of the structural and electronic variety of copper. Y/sub 2/Cu/sub 2/O/sub 5/ and Y/sub 2/BaCuO/sub 5/ were shown to be chain and layer magnetic systems, respectively. BaCuO/sub 2/, a complicated 3D structure, has interesting effects of exchange interaction manifested in the temperature-dependent EPR spectrum. YBa/sub 2/Cu/sub 3/O/sub 6/ has been shown to possess a Neel point at 450 K from EPR intensity variation with temperature.

  17. White Matter Abnormalities and Structural Hippocampal Disconnections in Amnestic Mild Cognitive Impairment and Alzheimer’s Disease

    PubMed Central

    Rowley, Jared; Fonov, Vladimir; Wu, Ona; Eskildsen, Simon Fristed; Schoemaker, Dorothee; Wu, Liyong; Mohades, Sara; Shin, Monica; Sziklas, Viviane; Cheewakriengkrai, Laksanun; Shmuel, Amir; Dagher, Alain; Gauthier, Serge; Rosa-Neto, Pedro

    2013-01-01

    The purpose of this project was to evaluate white matter degeneration and its impact on hippocampal structural connectivity in patients with amnestic mild cognitive impairment, non-amnestic mild cognitive impairment and Alzheimer’s disease. We estimated white matter fractional anisotropy, mean diffusivity and hippocampal structural connectivity in two independent cohorts. The ADNI cohort included 108 subjects [25 cognitively normal, 21 amnestic mild cognitive impairment, 47 non-amnestic mild cognitive impairment and 15 Alzheimer’s disease]. A second cohort included 34 subjects [15 cognitively normal and 19 amnestic mild cognitive impairment] recruited in Montreal. All subjects underwent clinical and neuropsychological assessment in addition to diffusion and T1 MRI. Individual fractional anisotropy and mean diffusivity maps were generated using FSL-DTIfit. In addition, hippocampal structural connectivity maps expressing the probability of connectivity between the hippocampus and cortex were generated using a pipeline based on FSL-probtrackX. Voxel-based group comparison statistics of fractional anisotropy, mean diffusivity and hippocampal structural connectivity were estimated using Tract-Based Spatial Statistics. The proportion of abnormal to total white matter volume was estimated using the total volume of the white matter skeleton. We found that in both cohorts, amnestic mild cognitive impairment patients had 27-29% white matter volume showing higher mean diffusivity but no significant fractional anisotropy abnormalities. No fractional anisotropy or mean diffusivity differences were observed between non-amnestic mild cognitive impairment patients and cognitively normal subjects. Alzheimer’s disease patients had 66.3% of normalized white matter volume with increased mean diffusivity and 54.3% of the white matter had reduced fractional anisotropy. Reduced structural connectivity was found in the hippocampal connections to temporal, inferior parietal

  18. Abnormal thermal expansion, multiple transitions, magnetocaloric effect, and electronic structure of Gd{sub 6}Co{sub 4.85}

    SciTech Connect

    Zhang, Jiliang; Zheng, Zhigang; Shan, Guangcun E-mail: bobev@udel.edu; Bobev, Svilen E-mail: bobev@udel.edu; Shek, Chan Hung E-mail: bobev@udel.edu

    2015-10-07

    The structure of known Gd{sub 4}Co{sub 3} compound is re-determined as Gd{sub 6}Co{sub 4.85}, adopting the Gd{sub 6}Co{sub 1.67}Si{sub 3} structure type, which is characterized by two disorder Co sites filling the Gd octahedral and a short Gd-Gd distance within the octahedra. The compound shows uniaxial negative thermal expansion in paramagnetic state, significant negative expansion in ferromagnetic state, and positive expansion below ca. 140 K. It also exhibits large magnetocaloric effect, with an entropy change of −6.4 J kg{sup −1} K{sup −1} at 50 kOe. In the lattice of the compound, Co atoms at different sites show different spin states. It was confirmed by the X-ray photoelectron spectra and calculation of electronic structure and shed lights on the abnormal thermal expansion. The stability of such compound and the origin of its magnetism are also discussed based on measured and calculated electronic structures.

  19. Improvement of white matter and functional connectivity abnormalities by repetitive transcranial magnetic stimulation in crossed aphasia in dextral.

    PubMed

    Lu, Haitao; Wu, Haiyan; Cheng, Hewei; Wei, Dongjie; Wang, Xiaoyan; Fan, Yong; Zhang, Hao; Zhang, Tong

    2014-01-01

    As a special aphasia, the occurrence of crossed aphasia in dextral (CAD) is unusual. This study aims to improve the language ability by applying 1 Hz repetitive transcranial magnetic stimulation (rTMS). We studied multiple modality imaging of structural connectivity (diffusion tensor imaging), functional connectivity (resting fMRI), PET, and neurolinguistic analysis on a patient with CAD. Furthermore, we applied rTMS of 1 Hz for 40 times and observed the language function improvement. The results indicated that a significantly reduced structural and function connectivity was found in DTI and fMRI data compared with the control. The PET imaging showed hypo-metabolism in right hemisphere and left cerebellum. In conclusion, one of the mechanisms of CAD is that right hemisphere is the language dominance. Stimulating left Wernicke area could improve auditory comprehension, stimulating left Broca's area could enhance expression, and the results outlasted 6 months by 1 Hz rTMS balancing the excitability inter-hemisphere in CAD. PMID:25419415

  20. Micro Structure of Nickel in Spin Coated Thin Film Magnets

    NASA Astrophysics Data System (ADS)

    Vides, Katherine; Dahanayake, Rasika; Samarasekara, Pubudu; Dehipawala, Sunil

    2014-03-01

    Micro-Structure of Nickel compounds in thin film magnets was investigated using Extended X ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES). These thin film magnets were prepared by spin coating several layers of precursor containing iron and Nickel on a glass substrate. Thickness of the films was controlled by spin rate. Several magnets were prepared with different thicknesses and each film was annealed to either 200C or 350c in air. Variation of oxidation state and nearest neighbor bond lengths of each magnet was measured to characterize Ni in the film.

  1. An instrument for precision magnetic measurements of large magnetic structures

    NASA Astrophysics Data System (ADS)

    Beltrán, D.; Bordas, J.; Campmany, J.; Molins, A.; Perlas, J. A.; Traveria, M.

    2001-02-01

    A high precision-system for measuring the three-dimensional distribution of magnetic fields over large volumes, such as those produced by accelerator magnets, has been designed and commissioned. This instrument can be calibrated to a precision of ±1 G for magnetic fields of up to 1.5 T by means of an NMR system. A moving arm containing a 3D Hall probe scans the volume (up to 500×250×3000 mm 3) with a precision of ±50 μm in any direction. After appropriate identification of the various sources of error, and the optimisation of the various parts of the instrument where they are generated, an overall precision of ±2 G has been achieved, i.e. a relative precision of ±2×10 -4 for a nominal field of 1 T.

  2. Unraveling chromatin structure using magnetic tweezers

    NASA Astrophysics Data System (ADS)

    van Noort, John

    2010-03-01

    The compact, yet dynamic organization of chromatin plays an essential role in regulating gene expression. Although the static structure of chromatin fibers has been studied extensively, the controversy about the higher order folding remains. The compaction of eukaryotic DNA into chromatin has been implicated in the regulation of all DNA processes. To understand the relation between gene regulation and chromatin structure it is essential to uncover the mechanisms by which chromatin fibers fold and unfold. We used magnetic tweezers to probe the mechanical properties of individual nucleosomes and chromatin fibers consisting of a single, well-defined array of 25 nucleosomes. From these studies five major features appeared upon forced extension of chromatin fibers: the elastic stretching of chromatin's higher order structure, the breaking of internucleosomal contacts, unwrapping of the first turn of DNA, unwrapping of the second turn of DNA, and the dissociation of histone octamers. These events occur sequentially at the increasing force. Neighboring nucleosomes stabilize DNA folding into a nucleosome relative to isolated nucleosomes. When an array of nucleosomes is folded into a 30 nm fiber, representing the first level of chromatin condensation, the fiber stretched like a Hookian spring at forces up to 4 pN. Together with a nucleosome-nucleosome stacking energy of 14 kT this points to a solenoid as the underlying topology of the 30 nm fiber. Surprisingly, linker histones do not affect the length or stiffness of the fibers, but stabilize fiber folding up to forces of 7 pN. The stiffness of the folded chromatin fiber points at histone tails that mediate nucleosome stacking. Fibers with a nucleosome repeat length of 167 bp instead of 197 bp are significantly stiffer, consistent with a two-start helical arrangement. The extensive thermal breathing of the chromatin fiber that is a consequence of the observed high compliance provides a structural basis for understanding the

  3. Magnetic field modulation of chirooptical effects in magnetoplasmonic structures.

    PubMed

    Armelles, Gaspar; Caballero, Blanca; Prieto, Patricia; García, Fernando; Cebollada, Alfonso; González, Maria Ujué; García-Martin, Antonio

    2014-04-01

    In this work we analyse the magnetic field effects on the chirooptical properties of magnetoplasmonic chiral structures. The structures consist of two-dimensional arrays of Au gammadions in which thin layers of Co have been inserted. Due to the magnetic properties of the Au/Co interface the structures have perpendicular magnetic anisotropy which favours magnetic saturation along the surface normal, allowing magnetic field modulation of the chirooptical response with moderate magnetic fields. These structures have two main resonances. The resonance at 850 nm has a larger chirooptical response than the resonance at 650 nm, which, on the other hand, exhibits a larger magnetic field modulation of its chirooptical response. This dissimilar behaviour is due to the different physical origin of the chirooptical and magneto-optical responses. Whereas the chirooptical effects are due to the geometry of the structures, the magneto-optical response is related to the intensity of the electromagnetic field in the magnetic (Co) layers. We also show that the optical chirality can be modulated by the applied magnetic field, which suggests that magnetoplasmonic chiral structures could be used to develop new strategies for chirooptical sensing. PMID:24569696

  4. Magnetic field modulation of chirooptical effects in magnetoplasmonic structures.

    PubMed

    Armelles, Gaspar; Caballero, Blanca; Prieto, Patricia; García, Fernando; Cebollada, Alfonso; González, Maria Ujué; García-Martin, Antonio

    2014-04-01

    In this work we analyse the magnetic field effects on the chirooptical properties of magnetoplasmonic chiral structures. The structures consist of two-dimensional arrays of Au gammadions in which thin layers of Co have been inserted. Due to the magnetic properties of the Au/Co interface the structures have perpendicular magnetic anisotropy which favours magnetic saturation along the surface normal, allowing magnetic field modulation of the chirooptical response with moderate magnetic fields. These structures have two main resonances. The resonance at 850 nm has a larger chirooptical response than the resonance at 650 nm, which, on the other hand, exhibits a larger magnetic field modulation of its chirooptical response. This dissimilar behaviour is due to the different physical origin of the chirooptical and magneto-optical responses. Whereas the chirooptical effects are due to the geometry of the structures, the magneto-optical response is related to the intensity of the electromagnetic field in the magnetic (Co) layers. We also show that the optical chirality can be modulated by the applied magnetic field, which suggests that magnetoplasmonic chiral structures could be used to develop new strategies for chirooptical sensing.

  5. Nonlinear dynamics of breathers in the spiral structures of magnets

    NASA Astrophysics Data System (ADS)

    Kiselev, V. V.; Raskovalov, A. A.

    2016-06-01

    The structure and properties of pulsating solitons (breathers) in the spiral structures of magnets are analyzed within the sine-Gordon model. The breather core pulsations are shown to be accompanied by local shifts and oscillations of the spiral structure with the formation of "precursors" and "tails" in the moving soliton. The possibilities for the observation and excitation of breathers in the spiral structures of magnets and multiferroics are discussed.

  6. Clues for genesis of magnetic field structure of Mercury

    NASA Astrophysics Data System (ADS)

    Hiremath, K. M.

    2012-07-01

    Recent space observations suggest that Mercury inherits a weak and predominantly large-scale steady dipole like magnetic field structure. Present popular paradigm is to invoke most promising geodynamo like phenomenon that requires the main ingredients such as either a full or partial convection of the interior and fast rotation such that magnetic (Lorentz) and Coriolis forces are of similar order of magnitudes. Hence, the ratio of Lorentz to Coriolis force, called the Elsasser number Λ, must be order of unity. Contrary to the expectation, Mercury rotates so slow that Elsasser number turns out to be << 1. There are also other alternative models to explain genesis of magnetic field structure of Mercury. With the observed constraint of Mercury's atmospheric magnetic field structure, internal magnetic field structure is obtained as a solution of magnetic diffusion equation in the core and a combined multipolar (dipole and quadrupole like magnetic field structures embedded in the uniform field) solution of a current free like magnetic field structure in the mantle and in the atmosphere. Magnetic diffusion time scales are estimated to be ˜ billion years suggesting that present day magnetic field structure might be of primordial origin. In order to reconcile with the experimental fact that, as temperature of Mercury's iron core is above Curie temperature and primordial magnetic field structure must be non-existent, it is proposed that permanency of such a large-scale magnetic field structure of the planet is attained during Mercury's early evolutionary history of heavy bombardments by the asteroids and comets leaving their imprints as craters on this planet. That means the solar system bodies that have heavy bombardments with high density craters during the early epochs of such catastrophic events should have strong magnetic field structures. Is this hypothesis universal? Can this hypothesis gives some clues regarding presence or absence of magnetic field structure of

  7. Studies of the magnetic structure at the ferromagnet - antiferromagnet interface

    SciTech Connect

    Scholl, A.; Nolting, F.; Stohr, J.; Luning, J.; Seo, J.W.; Locquet, J.-P.; Anders, S.; Ohldag, H.; Padmore, H.A.

    2001-01-02

    Antiferromagnetic layers are a scientifically challenging component in magneto-electronic devices such as magnetic sensors in hard disk heads, or magnetic RAM elements. In this paper we show that photo-electron emission microscopy (PEEM) is capable of determining the magnetic structure at the interface of ferromagnets and antiferromagnets with high spatial resolution (down to 20 nm). Dichroism effects at the L edges of the magnetic 3d transition metals, using circularly or linearly polarized soft x-rays from a synchrotron source, give rise to a magnetic image contrast. Images, acquired with the PEEM2 experiment at the Advanced Light Source, show magnetic contrast for antiferromagnetic LaFeO{sub 3}, microscopically resolving the magnetic domain structure in an antiferromagnetically ordered thin film for the first time. Magnetic coupling between LaFeO{sub 3} and an adjacent Co layer results in a complete correlation of their magnetic domain structures. From field dependent measurements a unidirectional anisotropy resulting in a local exchange bias of up to 30 Oe in single domains could be deduced. The elemental specificity and the quantitative magnetic sensitivity render PEEM a perfect tool to study magnetic coupling effects in multi-layered thin film samples.

  8. Magnetic Structure Determinations at NBS/NIST

    PubMed Central

    Lynn, J. W.; Borchers, J. A.; Huang, Q.; Santoro, A.; Erwin, R. W.

    2001-01-01

    Magnetic neutron scattering plays a central role in determining and understanding the microscopic properties of a vast variety of magnetic systems, from the fundamental nature, symmetry, and dynamics of magnetically ordered materials to elucidating the magnetic characteristics essential in technological applications. From the early days of neutron scattering measurements at NBS/NIST, magnetic diffraction studies have been a central theme involving many universities, industrial and government labs from around the United States and worldwide. Such measurements have been used to determine the spatial arrangement and directions of the atomic magnetic moments, the atomic magnetization density of the individual atoms in the material, and the value of the ordered moments as a function of thermodynamic parameters such as temperature, pressure, and applied magnetic field. These types of measurements have been carried out on single crystals, powders, thin films, and artificially grown multilayers, and often the information collected can be obtained by no other experimental technique. This article presents, in an historical perspective, a few examples of work carried out at the NIST Center for Neutron Research (NCNR), and discusses the key role that the Center can expect to play in future magnetism research. PMID:27500056

  9. [Assemble of magnetic nanoparticles into the structure of cisplatin liposome].

    PubMed

    Wang, Lu; Yang, Cai-qin; Wang, Jing

    2011-05-01

    Effects of different procedures of magnetic nanoparticles into the liposome structure on the distribution of magnetic particles in the liposome were investigated. Magnetic liposomes with high-encapsulating rate of cisplatin (CDDP) were obtained. Fe3O4 magnetic nanoparticles which was modified by organic functional group on surface was synthesized by an one-step modified hydrothermal method. The CDDP magnetic liposomes were prepared by a film scattering-ultrasonic technique and the concentrations of CDDP in the liposomes were measured by graphite furnace atomic absorbance spectroscopy. Magnetic liposomes with different microstructure were prepared by the two different procedures, where the magnetic particles were combined with phospholipid before the film preparation to form liposome in procedure I, and drug solution and the magnetic particles were mixed before hydrating the lipids film to form liposome in procedure II. The liposome structure was observed by transmission electron microscope (TEM). The CDDP magnetic liposomes were prepared by the optimized method which was selected by orthogonal test. Encapsulation rate of the magnetic particles distributed in the phospholipid bilayer through the procedure I was 34.90%. While liposome, produced by the procedure II technique, contained magnetic particles in the interior aqueous compartment, which encapsulation rate was 28.34%. Encapsulation rates of both I and II were higher than that of conventional liposome. The release profile of all the three different liposomes in vitro fitted with a first-order equation. Because of distribution of magnetic particles in the phospholipid bilayer, the skeleton of phospholipid bilayer was changed. The releasing tl/2 of magnetic liposomes produced by the procedure I technique is 9 h, which is shorter than that of the other two liposomes. Assemble of magnetic nanoparticles into the structure of liposome was succeeded by the procedure I, which showed superiority than by procedure II

  10. Unique magnetic structure of YbCo2Si2

    NASA Astrophysics Data System (ADS)

    Mufti, N.; Kaneko, K.; Hoser, A.; Gutmann, M.; Geibel, C.; Krellner, C.; Stockert, O.

    2016-07-01

    We report on the results of powder and single-crystal neutron diffraction to investigate the magnetic order in YbCo2Si2 below the Néel temperature TN=1.7 K in detail. Two different magnetically ordered phases can clearly be distinguished. At lowest temperatures a commensurate magnetic structure with a propagation vector k1=(0.25 0.25 1 ) is found, while the intermediate phase (T >0.9 K) is characterized by an incommensurate magnetic structure with k2=(0.25 0.086 1 ) . The magnetic structure in YbCo2Si2 is in marked contrast to all other known R Co2Si2 compounds (R = rare earth element) likely due to some itineracy of the Yb 4 f states being responsible for the magnetism.

  11. Abnormal bipolar resistive switching behavior in a Pt/GaO{sub 1.3}/Pt structure

    SciTech Connect

    Guo, D. Y.; Wu, Z. P.; Zhang, L. J.; Yang, T.; Hu, Q. R.; Lei, M.; Tang, W. H. E-mail: pgli@zstu.edu.cn; Li, P. G. E-mail: pgli@zstu.edu.cn; Li, L. H.

    2015-07-20

    A stable and repeatable abnormal bipolar resistive switching behavior was observed in a Pt/GaO{sub 1.3}/Pt sandwich structure without an electroforming process. The low resistance state (LRS) and the high resistance state (HRS) of the device can be distinguished clearly and be switched reversibly under a train of the voltage pulses. The LRS exhibits a conduction of electron tunneling, while the HRS shows a conduction of Schottky-type. The observed phenomena are considered to be related to the migration of oxygen vacancies which changes the space charge region width of the metal/semiconductor interface and results in a different electron transport mechanism.

  12. Structural and magnetic etch damage in CoFeB

    SciTech Connect

    Krayer, L.; Lau, J. W.; Kirby, B. J.

    2014-05-07

    A detailed understanding of the interfacial properties of thin films used in magnetic media is critical for the aggressive component scaling required for continued improvement in storage density. In particular, it is important to understand how common etching and milling processes affect the interfacial magnetism. We have used polarized neutron reflectometry and transmission electron microscopy to characterize the structural and magnetic properties of an ion beam etched interface of a CoFeB film. We found that the etching process results in a sharp magnetic interface buried under a nanometer scale layer of non-magnetic, compositionally distinct material.

  13. Magnetic coupling at perovskite and rock-salt structured interfaces

    SciTech Connect

    Matvejeff, M.; Ahvenniemi, E.; Takahashi, R.; Lippmaa, M.

    2015-10-05

    We study magnetic coupling between hole-doped manganite layers separated by either a perovskite or a rock-salt barrier of variable thickness. Both the type and the quality of the interface have a strong impact on the minimum critical barrier thickness where the manganite layers become magnetically decoupled. A rock-salt barrier layer only 1 unit cell (0.5 nm) thick remains insulating and is able to magnetically de-couple the electrode layers. The technique can therefore be used for developing high-performance planar oxide electronic devices such as magnetic tunnel junctions and quantum well structures that depend on magnetically and electronically sharp heterointerfaces.

  14. Catechin averts experimental diabetes mellitus-induced vascular endothelial structural and functional abnormalities.

    PubMed

    Bhardwaj, Pooja; Khanna, Deepa; Balakumar, Pitchai

    2014-03-01

    Diabetes mellitus is associated with an induction of vascular endothelial dysfunction (VED), an initial event that could lead to the pathogenesis of atherosclerosis and hypertension. Previous studies showed that catechin, a key component of green tea, possesses vascular beneficial effects. We investigated the effect of catechin hydrate in diabetes mellitus-induced experimental vascular endothelial abnormalities (VEA). Streptozotocin (50 mg/kg, i.p., once) administration to rats produced diabetes mellitus, which subsequently induced VEA in 8 weeks by markedly attenuating acetylcholine-induced endothelium-dependent relaxation in the isolated aortic ring preparation, decreasing aortic and serum nitrite/nitrate concentrations and impairing aortic endothelial integrity. These abnormalities in diabetic rats were accompanied with elevated aortic superoxide anion generation and serum lipid peroxidation in addition to hyperglycemia. Catechin hydrate treatment (50 mg/kg/day p.o., 3 weeks) markedly prevented diabetes mellitus-induced VEA and vascular oxidative stress. Intriguingly, in vitro incubation of L-NAME (100 μM), an inhibitor of nitric oxide synthase, or Wortmannin (100 nM), a selective inhibitor of phosphatidylinositol 3-kinase (PI3K), markedly prevented catechin hydrate-induced improvement in acetylcholine-provoked endothelium-dependent relaxation in the diabetic rat aorta. Moreover, catechin hydrate treatment considerably reduced the elevated level of serum glucose in diabetic rats. In conclusion, catechin hydrate treatment prevents diabetes mellitus-induced VED through the activation of endothelial PI3K signal and subsequent activation of eNOS and generation of nitric oxide. In addition, reduction in high glucose, vascular oxidative stress, and lipid peroxidation might additionally contribute to catechin hydrate-associated prevention of diabetic VEA. PMID:24048981

  15. Abnormal epithelial structure and chronic lung inflammation after repair of chlorine-induced airway injury

    PubMed Central

    Mo, Yiqun; Chen, Jing; Humphrey, David M.; Fodah, Ramy A.; Warawa, Jonathan M.

    2014-01-01

    Chlorine is a toxic gas used in a variety of industrial processes and is considered a chemical threat agent. High-level chlorine exposure causes acute lung injury, but the long-term effects of acute chlorine exposure are unclear. Here we characterized chronic pulmonary changes following acute chlorine exposure in mice. A/J mice were exposed to 240 parts per million-hour chlorine or sham-exposed to air. Chlorine inhalation caused sloughing of bronchial epithelium 1 day after chlorine exposure, which was repaired with restoration of a pseudostratified epithelium by day 7. The repaired epithelium contained an abnormal distribution of epithelial cells containing clusters of club or ciliated cells rather than the uniformly interspersed pattern of these cells in unexposed mice. Although the damaged epithelium in A/J mice was repaired rapidly, and minimal airway fibrosis was observed, chlorine-exposed mice developed pneumonitis characterized by infiltration of alveoli with neutrophils and prominent, large, foamy macrophages. Levels of CXCL1/KC, CXCL5/LPS-induced CXC chemokine, granulocyte colony-stimulating factor, and VEGF in bronchoalveolar (BAL) fluid from chlorine-exposed mice showed steadily increasing trends over time. BAL protein levels were increased on day 4 and remained elevated out to day 28. The number of bacteria cultured from lungs of chlorine-exposed mice 4 wk after exposure was not increased compared with sham-exposed mice, indicating that the observed pneumonitis was not driven by bacterial infection of the lung. The results indicate that acute chlorine exposure may cause chronic abnormalities in the lungs despite rapid repair of injured epithelium. PMID:25398987

  16. Abnormal epithelial structure and chronic lung inflammation after repair of chlorine-induced airway injury.

    PubMed

    Mo, Yiqun; Chen, Jing; Humphrey, David M; Fodah, Ramy A; Warawa, Jonathan M; Hoyle, Gary W

    2015-01-15

    Chlorine is a toxic gas used in a variety of industrial processes and is considered a chemical threat agent. High-level chlorine exposure causes acute lung injury, but the long-term effects of acute chlorine exposure are unclear. Here we characterized chronic pulmonary changes following acute chlorine exposure in mice. A/J mice were exposed to 240 parts per million-hour chlorine or sham-exposed to air. Chlorine inhalation caused sloughing of bronchial epithelium 1 day after chlorine exposure, which was repaired with restoration of a pseudostratified epithelium by day 7. The repaired epithelium contained an abnormal distribution of epithelial cells containing clusters of club or ciliated cells rather than the uniformly interspersed pattern of these cells in unexposed mice. Although the damaged epithelium in A/J mice was repaired rapidly, and minimal airway fibrosis was observed, chlorine-exposed mice developed pneumonitis characterized by infiltration of alveoli with neutrophils and prominent, large, foamy macrophages. Levels of CXCL1/KC, CXCL5/LPS-induced CXC chemokine, granulocyte colony-stimulating factor, and VEGF in bronchoalveolar (BAL) fluid from chlorine-exposed mice showed steadily increasing trends over time. BAL protein levels were increased on day 4 and remained elevated out to day 28. The number of bacteria cultured from lungs of chlorine-exposed mice 4 wk after exposure was not increased compared with sham-exposed mice, indicating that the observed pneumonitis was not driven by bacterial infection of the lung. The results indicate that acute chlorine exposure may cause chronic abnormalities in the lungs despite rapid repair of injured epithelium.

  17. Age-related structural abnormalities in the human retina-choroid complex revealed by two-photon excited autofluorescence imaging.

    PubMed

    Han, Meng; Giese, Guenter; Schmitz-Valckenberg, Steffen; Bindewald-Wittich, Almut; Holz, Frank G; Yu, Jiayi; Bille, Josef F; Niemz, Markolf H

    2007-01-01

    The intensive metabolism of photoreceptors is delicately maintained by the retinal pigment epithelium (RPE) and the choroid. Dysfunction of either the RPE or choroid may lead to severe damage to the retina. Two-photon excited autofluorescence (TPEF) from endogenous fluorophores in the human retina provides a novel opportunity to reveal age-related structural abnormalities in the retina-choroid complex prior to apparent pathological manifestations of age-related retinal diseases. In the photoreceptor layer, the regularity of the macular photoreceptor mosaic is preserved during aging. In the RPE, enlarged lipofuscin granules demonstrate significantly blue-shifted autofluorescence, which coincides with the depletion of melanin pigments. Prominent fibrillar structures in elderly Bruch's membrane and choriocapillaries represent choroidal structure and permeability alterations. Requiring neither slicing nor labeling, TPEF imaging is an elegant and highly efficient tool to delineate the thick, fragile, and opaque retina-choroid complex, and may provide clues to the trigger events of age-related macular degeneration.

  18. Short Large-Amplitude Magnetic Structures (SLAMS) at Venus

    NASA Technical Reports Server (NTRS)

    Collinson, G. A.; Wilson, L. B.; Sibeck, D. G.; Shane, N.; Zhang, T. L.; Moore, T. E.; Coates, A. J.; Barabash, S.

    2012-01-01

    We present the first observation of magnetic fluctuations consistent with Short Large-Amplitude Magnetic Structures (SLAMS) in the foreshock of the planet Venus. Three monolithic magnetic field spikes were observed by the Venus Express on the 11th of April 2009. The structures were approx.1.5->11s in duration, had magnetic compression ratios between approx.3->6, and exhibited elliptical polarization. These characteristics are consistent with the SLAMS observed at Earth, Jupiter, and Comet Giacobini-Zinner, and thus we hypothesize that it is possible SLAMS may be found at any celestial body with a foreshock.

  19. Characterization of tumor microvascular structure and permeability: comparison between magnetic resonance imaging and intravital confocal imaging

    PubMed Central

    Reitan, Nina Kristine; Thuen, Marte; Goa, Pål Erik; de Lange Davies, Catharina

    2010-01-01

    Solid tumors are characterized by abnormal blood vessel organization, structure, and function. These abnormalities give rise to enhanced vascular permeability and may predict therapeutic responses. The permeability and architecture of the microvasculature in human osteosarcoma tumors growing in dorsal window chambers in athymic mice were measured by confocal laser scanning microscopy (CLSM) and dynamic contrast enhanced magnetic resonance imaging (DCE-MRI). Dextran (40 kDa) and Gadomer were used as molecular tracers for CLSM and DCE-MRI, respectively. A significant correlation was found between permeability indicators. The extravasation rate Ki as measured by CLSM correlated positively with DCE-MRI parameters, such as the volume transfer constant Ktrans and the initial slope of the contrast agent concentration-time curve. This demonstrates that these two techniques give complementary information. Extravasation was further related to microvascular structure and was found to correlate with the fractal dimension and vascular density. The structural parameter values that were obtained from CLSM images were higher for abnormal tumor vasculature than for normal vessels. PMID:20615006

  20. A Magnetic Field Sensor Based on a Magnetic Fluid-Filled FP-FBG Structure.

    PubMed

    Xia, Ji; Wang, Fuyin; Luo, Hong; Wang, Qi; Xiong, Shuidong

    2016-04-29

    Based on the characteristic magnetic-controlled refractive index property, in this paper, a magnetic fluid is used as a sensitive medium to detect the magnetic field in the fiber optic Fabry-Perot (FP) cavity. The temperature compensation in fiber Fabry-Perot magnetic sensor is demonstrated and achieved. The refractive index of the magnetic fluid varies with the applied magnetic field and external temperature, and a cross-sensitivity effect of the temperature and magnetic field occurs in the Fabry-Perot magnetic sensor and the accuracy of magnetic field measurements is affected by the thermal effect. In order to overcome this problem, we propose a modified sensor structure. With a fiber Bragg grating (FBG) written in the insert fiber end of the Fabry-Perot cavity, the FBG acts as a temperature compensation unit for the magnetic field measurement and it provides an effective solution to the cross-sensitivity effect. The experimental results show that the sensitivity of magnetic field detection improves from 0.23 nm/mT to 0.53 nm/mT, and the magnetic field measurement resolution finally reaches 37.7 T. The temperature-compensated FP-FBG magnetic sensor has obvious advantages of small volume and high sensitivity, and it has a good prospect in applications in the power industry and national defense technology areas.

  1. A Magnetic Field Sensor Based on a Magnetic Fluid-Filled FP-FBG Structure

    PubMed Central

    Xia, Ji; Wang, Fuyin; Luo, Hong; Wang, Qi; Xiong, Shuidong

    2016-01-01

    Based on the characteristic magnetic-controlled refractive index property, in this paper, a magnetic fluid is used as a sensitive medium to detect the magnetic field in the fiber optic Fabry-Perot (FP) cavity. The temperature compensation in fiber Fabry-Perot magnetic sensor is demonstrated and achieved. The refractive index of the magnetic fluid varies with the applied magnetic field and external temperature, and a cross-sensitivity effect of the temperature and magnetic field occurs in the Fabry-Perot magnetic sensor and the accuracy of magnetic field measurements is affected by the thermal effect. In order to overcome this problem, we propose a modified sensor structure. With a fiber Bragg grating (FBG) written in the insert fiber end of the Fabry-Perot cavity, the FBG acts as a temperature compensation unit for the magnetic field measurement and it provides an effective solution to the cross-sensitivity effect. The experimental results show that the sensitivity of magnetic field detection improves from 0.23 nm/mT to 0.53 nm/mT, and the magnetic field measurement resolution finally reaches 37.7 T. The temperature-compensated FP-FBG magnetic sensor has obvious advantages of small volume and high sensitivity, and it has a good prospect in applications in the power industry and national defense technology areas. PMID:27136564

  2. A Magnetic Field Sensor Based on a Magnetic Fluid-Filled FP-FBG Structure.

    PubMed

    Xia, Ji; Wang, Fuyin; Luo, Hong; Wang, Qi; Xiong, Shuidong

    2016-01-01

    Based on the characteristic magnetic-controlled refractive index property, in this paper, a magnetic fluid is used as a sensitive medium to detect the magnetic field in the fiber optic Fabry-Perot (FP) cavity. The temperature compensation in fiber Fabry-Perot magnetic sensor is demonstrated and achieved. The refractive index of the magnetic fluid varies with the applied magnetic field and external temperature, and a cross-sensitivity effect of the temperature and magnetic field occurs in the Fabry-Perot magnetic sensor and the accuracy of magnetic field measurements is affected by the thermal effect. In order to overcome this problem, we propose a modified sensor structure. With a fiber Bragg grating (FBG) written in the insert fiber end of the Fabry-Perot cavity, the FBG acts as a temperature compensation unit for the magnetic field measurement and it provides an effective solution to the cross-sensitivity effect. The experimental results show that the sensitivity of magnetic field detection improves from 0.23 nm/mT to 0.53 nm/mT, and the magnetic field measurement resolution finally reaches 37.7 T. The temperature-compensated FP-FBG magnetic sensor has obvious advantages of small volume and high sensitivity, and it has a good prospect in applications in the power industry and national defense technology areas. PMID:27136564

  3. Morphological abnormalities among lampreys

    USGS Publications Warehouse

    Manion, Patrick J.

    1967-01-01

    The experimental control of the sea lamprey (Petromyzon marinus) in the Great Lakes has required the collection of thousands of lampreys. Representatives of each life stage of the four species of the Lake Superior basin were examined for structural abnormalities. The most common aberration was the presence of additional tails. The accessory tails were always postanal and smaller than the normal tail. The point of origin varied; the extra tails occurred on dorsal, ventral, or lateral surfaces. Some of the extra tails were misshaped and curled, but others were normal in shape and pigment pattern. Other abnormalities in larval sea lampreys were malformed or twisted tails and bodies. The cause of the structural abnormalities is unknown. The presence of extra caudal fins could be genetically controlled, or be due to partial amputation or injury followed by abnormal regeneration. Few if any lampreys with structural abnormalities live to sexual maturity.

  4. Structuralization of Magnetic Nanoparticles Induced by Laser Heating in Magnetic Fluids

    NASA Astrophysics Data System (ADS)

    Kopčanský, P.; Timko, M.; Tomčo, L.; Koneracká, M.; Štelina, J.; Musil, C.

    2010-01-01

    The structuralization of magnetic particles in magnetic fluids due to the thermodiffusion induced by laser light illumination was experimentally observed in two types of magnetic fluids: one based on a mineral oil with magnetite particles covered by a monolayer of oleic acid as a surfactant and the other a kerosene-based magnetic fluid sterically stabilized by a double layer consisting of oleic acid and dodecylbenzenesulphonic acid (DBS). Forced Rayleigh scattering (FRS) showed different behaviors of magnetic particle structuralization in the observed magnetic fluids. While for the case of mineral oil-based magnetic fluids, there was observed a positive thermodiffusion ( S > 0), an indication of negative thermodiffusion ( S < 0) was observed in magnetic fluids based on kerosene. This was also confirmed by the time-dependent decay of a grating of magnetic particles. Numerical simulation of aggregation for the case of negative thermodiffusion was confirmed by the observed aggregation after laser illumination in kerosene-based magnetic fluids and enabled an estimated value of the negative Soret constant in the magnetic fluid studied ( S ≈ -10-2 K -1).

  5. Coronal Magnetic Structures for Homologous Eruptions

    NASA Astrophysics Data System (ADS)

    Lee, J.; Liu, C.; Jing, J.; Chae, J.

    2015-12-01

    Many studies have been made on homologous eruptions for their importance in understanding the flare energy build-up and release processes. We study the homologous eruptions that occurred in three active regions, NOAA 11444, 11283, and 12192, with emphasis on the coronal quantities derived from the nonlinear force-free field (NLFFF) extrapolation. The quantities include magnetic energy, electric current, and magnetic twist number, and decay index, computed from the high cadence photospheric vector magnetograms of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO). In addition, photospheric magnetic flux, flare ribbons and overlying field distribution are also examined to determine the changes associated with each eruption. As main results, we will present the difference between the homology of confined eruptions and that of eruptive ones, and variations of the coronal quantities with flare strength.

  6. Fractal structure of the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Klein, L. W.

    1985-01-01

    Under some conditions, time series of the interplanetary magnetic field strength and components have the properties of fractal curves. Magnetic field measurements made near 8.5 AU by Voyager 2 from June 5 to August 24, 1981 were self-similar over time scales from approximately 20 sec to approximately 3 x 100,000 sec, and the fractal dimension of the time series of the strength and components of the magnetic field was D = 5/3, corresponding to a power spectrum P(f) approximately f sup -5/3. Since the Kolmogorov spectrum for homogeneous, isotropic, stationary turbulence is also f sup -5/3, the Voyager 2 measurements are consistent with the observation of an inertial range of turbulence extending over approximately four decades in frequency. Interaction regions probably contributed most of the power in this interval. As an example, one interaction region is discussed in which the magnetic field had a fractal dimension D = 5/3.

  7. Evolving Magnetic Structures and Their Relation to Coronal Mass Ejections

    NASA Technical Reports Server (NTRS)

    Feynman, J.

    1996-01-01

    Solar activity regions are frequently concentrated into cluster which persist for many solar rotations. These activity complexes are associated with weak dispersed magnetic fields which are most apparent after the activity itself has ceased. We call this combination of persistent activity and dispersed Evolving Magnetic Structures (EMS). Here we show examples of EMSs and describe the evolution of an EMS associated with major Coronal Mass Ejections (CME) and other solar and magnetic disturbances.

  8. Influence of magnetic fields on structural martensitic transitions

    SciTech Connect

    Lashley, J C; Cooley, J C; Smith, J L; Fisher, R A; Modic, K A; Yang, X- D; Riseborough, P S; Opeil, C P; Finlayson, T R; Goddard, P A; Silhanek, A V

    2009-01-01

    We show evidence that a structural martensitic transition is related to significant changes in the electronic structure, as revealed in thermodynamic measurements made in high-magnetic fields. The magnetic field dependence is considered unusual as many influential investigations of martensitic transitions have emphasized that the structural transitions are primarily lattice dynamical and are driven by the entropy due to the phonons. We provide a theoretical framework which can be used to describe the effect of magnetic field on the lattice dynamics in which the field dependence originates from the dielectric constant.

  9. Unusual Structure and Magnetism in MnO Nanoclusters

    NASA Astrophysics Data System (ADS)

    Ganguly, Shreemoyee; Kabir, Mukul; Sanyal, Biplab; Mookerjee, Abhijit

    2011-03-01

    We report an unusual structural and magnetic evolution in stoichiometric MnO nanoclusters by an extensive and unbiased search through the potential energy surface within density functional theory. The (MnO)n nanoclusters adopt two-dimensional structures in size ranges in which Mnn nanoclusters are three-dimensional and regardless of the size of the nanocluster, the magnetic coupling is found to be antiferromagnetic, and is strikingly different from Mn-based molecular magnets. Both of these features are explained through the inherent electronic structures of the nanoclusters. We gratefully acknowledge financial support from Swedish Research Links program funded by VR/SIDA and Carl Tryggers Foundation, Sweden.

  10. Validation of the magnetic energy vs. helicity scaling in solar magnetic structures

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.; Moraitis, K.; Georgoulis, M. K.; Archontis, V.

    2014-10-01

    Aims: We assess the validity of the free magnetic energy - relative magnetic helicity diagram for solar magnetic structures. Methods: We used two different methods of calculating the free magnetic energy and the relative magnetic helicity budgets: a classical, volume-calculation nonlinear force-free (NLFF) method applied to finite coronal magnetic structures and a surface-calculation NLFF derivation that relies on a single photospheric or chromospheric vector magnetogram. Both methods were applied to two different data sets, namely synthetic active-region cases obtained by three-dimensional magneto-hydrodynamic (MHD) simulations and observed active-region cases, which include both eruptive and noneruptive magnetic structures. Results: The derived energy-helicity diagram shows a consistent monotonic scaling between relative helicity and free energy with a scaling index 0.84 ± 0.05 for both data sets and calculation methods. It also confirms the segregation between noneruptive and eruptive active regions and the existence of thresholds in both free energy and relative helicity for active regions to enter eruptive territory. Conclusions: We consider the previously reported energy-helicity diagram of solar magnetic structures as adequately validated and envision a significant role of the uncovered scaling in future studies of solar magnetism.

  11. Vertical Structure of Magnetized Accretion Disks around Young Stars

    NASA Astrophysics Data System (ADS)

    Lizano, S.; Tapia, C.; Boehler, Y.; D'Alessio, P.

    2016-01-01

    We model the vertical structure of the magnetized accretion disks that are subject to viscous and resistive heating and irradiation by the central star. We apply our formalism to the radial structure of the magnetized accretion disks that are threaded by the poloidal magnetic field dragged during the process of star formation, which was developed by Shu and coworkers. We consider disks around low-mass protostars, T Tauri, and FU Orionis stars, as well as two levels of disk magnetization: {λ }{sys}=4 (strongly magnetized disks) and {λ }{sys}=12 (weakly magnetized disks). The rotation rates of strongly magnetized disks have large deviations from Keplerian rotation. In these models, resistive heating dominates the thermal structure for the FU Ori disk, and the T Tauri disk is very thin and cold because it is strongly compressed by magnetic pressure; it may be too thin compared with observations. Instead, in the weakly magnetized disks, rotation velocities are close to Keplerian, and resistive heating is always less than 7% of the viscous heating. In these models, the T Tauri disk has a larger aspect ratio, which is consistent with that inferred from observations. All the disks have spatially extended hot atmospheres where the irradiation flux is absorbed, although most of the mass (˜90%-95%) is in the disk midplane. With the advent of ALMA one expects direct measurements of magnetic fields and their morphology at disk scales. It will then be possible to determine the mass-to-flux ratio of magnetized accretion disks around young stars, an essential parameter for their structure and evolution. Our models contribute to the understanding of the vertical structure and emission of these disks.

  12. Low Temperature Crystal Structure and Magnetic Properties of RAl2

    SciTech Connect

    Pathak, Arjun K.; Paudyal, Durga; Gschneidner, Karl A.; Pecharsky, Vitalij K.

    2014-01-08

    Low temperature crystal structure and magnetic properties of RAl2 (R = Pr and Nd) have been studied using temperature dependent powder x-ray diffraction, magnetization, and heat capacity measurements. Unlike PrAl2, NdAl2 retains cubic MgCu2-type structure from room temperature down to 5 K, which is also confirmed from first principles electronic structure calculations. The magnetization measurements show both PrAl2 and NdAl2 order ferromagnetically at TC = 32 K and 77 K, respectively. However, the magnetization measurements show the former is a hard ferromagnet compared to the latter which is a soft ferromagnetic material. The magnetic entropy change obtained from heat capacity measurements at ΔH = 30 kOe for PrAl2 and NdAl2 are 3.15 J mol-1 K-1 and 1.18 J mol-1 K-1, respectively.

  13. Local magnetic structure determination using polarized neutron holography

    SciTech Connect

    Szakál, Alex Markó, Márton Cser, László

    2015-05-07

    A unique and important property of the neutron is that it possesses magnetic moment. This property is widely used for determination of magnetic structure of crystalline samples observing the magnetic components of the diffraction peaks. Investigations of diffraction patterns give information only about the averaged structure of a crystal but for discovering of local spin arrangement around a specific (e.g., impurity) nucleus remains still a challenging problem. Neutron holography is a useful tool to investigate the local structure around a specific nucleus embedded in a crystal lattice. The method has been successfully applied experimentally in several cases using non-magnetic short range interaction of the neutron and the nucleus. A mathematical model of the hologram using interaction between magnetic moment of the atom and the neutron spin for polarized neutron holography is provided. Validity of a polarized neutron holographic experiment is demonstrated by applying the proposed method on model systems.

  14. Vertical Structure of Magnetized Accretion Disks Around Young Stars

    NASA Astrophysics Data System (ADS)

    Tapia, Carlos; Lizano, Susana

    2016-01-01

    We model the vertical structure of magnetized accretion disks subject to viscous and resistive heating, and irradiation by the central star. We apply our formalism to the radial structure of magnetized accretion disks threaded by a poloidal magnetic field dragged during the process of star formation developed by Shu and coworkers. We consider disks around low mass protostars, T Tauri, and FU Orionis stars. We consider two levels of disk magnetization, λsys = 4 (strongly magnetized disks), and λsys = 12 (weakly magnetized disks). The rotation rates of strongly magnetized disks have large deviations from Keplerian rotation. In these models, resistive heating dominates the thermal structure for the FU Ori disk. The T Tauri disk is very thin and cold because it is strongly compressed by magnetic pressure; it may be too thin compared with observations. Instead, in the weakly magnetized disks, rotation velocities are close to Keplerian, and resistive heating is always less than 7% of the viscous heating. In these models, the T Tauri disk has a larger aspect ratio, consistent with that inferred from observations. All the disks have spatially extended hot atmospheres where the irradiation flux is absorbed, although most of the mass (~ 90 - 95 %) is in the disk midplane.

  15. Three-Dimensional EMHD Simulation Studies of Nonlinear Magnetic Structures in Magnetized Plasmas

    SciTech Connect

    Eliasson, B.; Shukla, P. K.

    2008-10-15

    We present a numerical study of strongly nonlinear magnetic vortex-like structures, denoted whistler spheromaks, which have recently been observed in laboratory experiments. The whistler spheromaks are excited with a ring antenna immersed in the magnetized plasma, and are propagating away from the antenna with a constant speed along the ambient magnetic field lines. The wave magnetic field of the spheromaks are of the same order or larger than the ambient magnetic field, and consists of two parts, the poloidal field which is strong enough to reverse the magnetic field in the center of the spheromak, and the toroidal field. We demonstrate numerically that the latter is crucial for the propagation speed and direction of the spheromak, and that the whistler spheromaks are long-lived structures.

  16. Magnetic structure and magnetic properties of nanocrystalline and amorphous Fe-Zr-N films

    NASA Astrophysics Data System (ADS)

    Sheftel, Elena N.; Harin, Eugene V.; Tedzhetov, Valentin A.; Kiryukhantsev-Korneev, Philipp V.; Levashov, Evgeny A.; Perov, Nikolai S.; Titova, Alexandra O.

    2016-08-01

    Data on the magnetic structure and magnetic properties of Fe-Zr-N films, which were prepared by reactive magnetron sputtering of a heated target and deposited on glass substrates, are reported. Depending on the Zr content (from 3 to 35 at%), the film compositions are characterized by Zr-to-N (at%) ratio from 0.3 to 36.5. The magnetic properties (saturation magnetization Ms, coercive field Hc) and magnetic structure (effective local magnetic anisotropy field D1/2Ha, grain size 2Rc, effective anisotropy field of stochastic domain D1/2, relative stochastic domain size RL/Rc) of the films are discussed in interrelation with their phase and structural states. The coercive field of the studied ferromagnetic nanocrystalline films was shown to obey the relationship Hc~(2Rc)6 and depends on not only the grain size but also the local magnetic anisotropy field D1/2Ha. As the grain size of ferromagnetic phase decreases, the contribution of the magnetoelastic component to the coercive field decreases. It was shown, by examples of weak ferromagnetic and superparamagnetic films with amorphous and mixed (amorphous+nanocrystalline) structures containing a nonferromagnetic phase, that the magnetic properties reflect the real structural and phase state of the films, which cannot be revealed by the X-ray diffraction analysis.

  17. Meiotic abnormalities

    SciTech Connect

    1993-12-31

    Chapter 19, describes meiotic abnormalities. These include nondisjunction of autosomes and sex chromosomes, genetic and environmental causes of nondisjunction, misdivision of the centromere, chromosomally abnormal human sperm, male infertility, parental age, and origin of diploid gametes. 57 refs., 2 figs., 1 tab.

  18. Investigating brain community structure abnormalities in bipolar disorder using path length associated community estimation.

    PubMed

    Gadelkarim, Johnson J; Ajilore, Olusola; Schonfeld, Dan; Zhan, Liang; Thompson, Paul M; Feusner, Jamie D; Kumar, Anand; Altshuler, Lori L; Leow, Alex D

    2014-05-01

    In this article, we present path length associated community estimation (PLACE), a comprehensive framework for studying node-level community structure. Instead of the well-known Q modularity metric, PLACE utilizes a novel metric, Ψ(PL), which measures the difference between intercommunity versus intracommunity path lengths. We compared community structures in human healthy brain networks generated using these two metrics and argued that Ψ(PL) may have theoretical advantages. PLACE consists of the following: (1) extracting community structure using top-down hierarchical binary trees, where a branch at each bifurcation denotes a collection of nodes that form a community at that level, (2) constructing and assessing mean group community structure, and (3) detecting node-level changes in community between groups. We applied PLACE and investigated the structural brain networks obtained from a sample of 25 euthymic bipolar I subjects versus 25 gender- and age-matched healthy controls. Results showed community structural differences in posterior default mode network regions, with the bipolar group exhibiting left-right decoupling.

  19. MAGNETIC FIELD STRUCTURES TRIGGERING SOLAR FLARES AND CORONAL MASS EJECTIONS

    SciTech Connect

    Kusano, K.; Bamba, Y.; Yamamoto, T. T.; Iida, Y.; Toriumi, S.; Asai, A.

    2012-11-20

    Solar flares and coronal mass ejections, the most catastrophic eruptions in our solar system, have been known to affect terrestrial environments and infrastructure. However, because their triggering mechanism is still not sufficiently understood, our capacity to predict the occurrence of solar eruptions and to forecast space weather is substantially hindered. Even though various models have been proposed to determine the onset of solar eruptions, the types of magnetic structures capable of triggering these eruptions are still unclear. In this study, we solved this problem by systematically surveying the nonlinear dynamics caused by a wide variety of magnetic structures in terms of three-dimensional magnetohydrodynamic simulations. As a result, we determined that two different types of small magnetic structures favor the onset of solar eruptions. These structures, which should appear near the magnetic polarity inversion line (PIL), include magnetic fluxes reversed to the potential component or the nonpotential component of major field on the PIL. In addition, we analyzed two large flares, the X-class flare on 2006 December 13 and the M-class flare on 2011 February 13, using imaging data provided by the Hinode satellite, and we demonstrated that they conform to the simulation predictions. These results suggest that forecasting of solar eruptions is possible with sophisticated observation of a solar magnetic field, although the lead time must be limited by the timescale of changes in the small magnetic structures.

  20. Use of a Novel High-Resolution Magnetic Resonance Neurography Protocol to Detect Abnormal Dorsal Root Ganglia in Sjögren Patients With Neuropathic Pain

    PubMed Central

    Birnbaum, Julius; Duncan, Trisha; Owoyemi, Kristie; Wang, Kenneth C.; Carrino, John; Chhabra, Avneesh

    2014-01-01

    Abstract The diagnosis and treatment of patients with Sjögren syndrome (SS) with neuropathic pain pose several challenges. Patients with SS may experience unorthodox patterns of burning pain not conforming to a traditional “stocking-and-glove” distribution, which can affect the face, torso, and proximal extremities. This distribution of neuropathic pain may reflect mechanisms targeting the proximal-most element of the peripheral nervous system—the dorsal root ganglia (DRG). Skin biopsy can diagnose such a small-fiber neuropathy and is a surrogate marker of DRG neuronal cell loss. However, SS patients have been reported who have similar patterns of proximal neuropathic pain, despite having normal skin biopsy studies. In such cases, DRGs may be targeted by mechanisms not associated with neuronal cell loss. Therefore, alternative approaches are warranted to help characterize abnormal DRGs in SS patients with proximal neuropathic pain. We performed a systematic review of the literature to define the frequency and spectrum of SS peripheral neuropathies, and to better understand the attribution of SS neuropathic pain to peripheral neuropathies. We found that the frequency of SS neuropathic pain exceeded the prevalence of peripheral neuropathies, and that painful peripheral neuropathies occurred less frequently than neuropathies not always associated with pain. We developed a novel magnetic resonance neurography (MRN) protocol to evaluate DRG abnormalities. Ten SS patients with proximal neuropathic pain were evaluated by this MRN protocol, as well as by punch skin biopsies evaluating for intraepidermal nerve fiber density (IENFD) of unmyelinated nerves. Five patients had radiographic evidence of DRG abnormalities. Patients with MRN DRG abnormalities had increased IENFD of unmyelinated nerves compared to patients without MRN DRG abnormalities (30.2 [interquartile range, 4.4] fibers/mm vs. 11.0 [4.1] fibers/mm, respectively; p = 0.03). Two of these 5 SS patients

  1. Shock-induced modifications of magnetic minerals from impact structures

    NASA Astrophysics Data System (ADS)

    Kontny, A. M.

    2013-05-01

    Meteorite impact structures are an important feature of most planetary surfaces. The effects of shock waves on the intrinsic magnetic properties of minerals and rocks are therefore essential for the understanding of magnetization processes related to impact events on Earth and other planetary bodies. Despite numerous observations on natural settings (Carporzen et al. 2005; Mang et al. 2012), and experimental studies (Louzada et al. 2010, 2011; Gattacecca et al 2007; Gilder et al. 2004; Mang et al. 2013) there remain uncertainties concerning the rock magnetic properties and the magnetization process related to natural impact structures on Earth. In general, the magnetic signature of terrestrial impact structures is a combined effect between disrupted main regional magnetic trends due to shock and / or thermal demagnetization and high-amplitude, short-wavelength magnetic anomalies in the centre of intermediate to large impact structures. Some large structures (>40 km) are reported to exhibit central high-amplitude anomalies but the dominant magnetic feature is a magnetic low (Pilkington and Grieve 1992). The latter observation is especially important for the giant non-magnetized impact basins on Mars. Therefore numerous studies focused on the understanding of the demagnetization processes during shock pressure (Gilder et al. 2004; Louzada et al. 2010, 2011; Rochette et al. 2003). Many investigations of terrestrial impact structures, however, demonstrated that a natural remanent magnetization (NRM), which is imprinted into terrestrial rocks by the Earth magnetic field, is the main cause of the observed magnetic anomalies. Magnetic signatures of impact structures on Earth are therefore thought to be a combination of three parameters: (1) composition and magnetic properties of the target rocks, (2) modification of rocks and magnetic minerals (fracturing and melting) due to impact-related p-T conditions, (3) acquisition of new natural remanent magnetization (TRM, SRM or

  2. Magnetic structure in Dy/Sc superlattices

    NASA Astrophysics Data System (ADS)

    Tsui, F.; Flynn, C. P.; Beach, R. S.; Borchers, J. A.; Erwin, R. W.; Rhyne, J. J.

    1993-05-01

    We have investigated magnetic order in superlattices of Dy and Sc grown along the hcp c axis by molecular beam epitaxy (MBE) techniques. Our neutron diffraction experiments reveal that individual Dy layers order ferromagnetically below Tc˜150 K. The magnetic coherence length along the growth direction is less than the Dy-layer thickness. Previous studies of rare-earth superlattices with Y or Lu as spacer layers have shown that magnetic coherence propagates through sufficiently thin nonmagnetic interlayers. This arises from the long-range exchange interaction that originates from nesting features in the Fermi surface of the spacer material. The lack of coupling in Dy/Sc superlattices reflects the very different Fermi surface of Sc, with much weaker nesting than Y and Lu.

  3. Detection of zones of abnormal strains in structures using Gaussian curvature analysis

    SciTech Connect

    Lisle, R.J.

    1994-12-01

    Whereas some folds, such as those produced by flexural slip, do not theoretically entail strain within the folded surfaces, any surface involving double curvature (such as domes and saddles) cannot form without some stretching or contraction of the bedding. Whether straining of the surfaces is required during folding depends on the three-dimensional fold shape and, in particular, on the Gaussian curvature at points on the folded surface. Using this as a basis, I present a method for detecting zones of anomalously high strain in oil-field structures from Gaussian curvature analysis (GCA) of natural structures. The new method of GCA is suitable for analyzing surfaces that have been mapped seismically. A Gaussian curvature map of the structure is a principal outcome of the analysis and can be used to predict the density of strain-related subseismic structures, such as small-scale fracturing. The Goose Egg dome, near Casper, Wyoming, is analyzed and provides an example of GCA. In this structure, a relationship is observed between fracture densities and Gaussian curvature.

  4. Shape Abnormalities of Subcortical and Ventricular Structures in Mild Cognitive Impairment and Alzheimer’s Disease: Detecting, Quantifying, and Predicting

    PubMed Central

    Tang, Xiaoying; Holland, Dominic; Dale, Anders M.; Younes, Laurent; Miller, Michael I.

    2015-01-01

    This article assesses the feasibility of using shape information to detect and quantify the subcortical and ventricular structural changes in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) patients. We first demonstrate structural shape abnormalities in MCI and AD as compared with healthy controls (HC). Exploring the development to AD, we then divide the MCI participants into two subgroups based on longitudinal clinical information: (1) MCI patients who remained stable; (2) MCI patients who converted to AD over time. We focus on seven structures (amygdala, hippocampus, thalamus, caudate, putamen, globus pallidus, and lateral ventricles) in 754 MR scans (210 HC, 369 MCI of which 151 converted to AD over time, and 175 AD). The hippocampus and amygdala were further subsegmented based on high field 0.8 mm isotropic 7.0T scans for finer exploration. For MCI and AD, prominent ventricular expansions were detected and we found that these patients had strongest hippocampal atrophy occurring at CA1 and strongest amygdala atrophy at the basolateral complex. Mild atrophy in basal ganglia structures was also detected in MCI and AD. Stronger atrophy in the amygdala and hippocampus, and greater expansion in ventricles was observed in MCI converters, relative to those MCI who remained stable. Furthermore, we performed principal component analysis on a linear shape space of each structure. A subsequent linear discriminant analysis on the principal component values of hippocampus, amygdala, and ventricle leads to correct classification of 88% HC subjects and 86% AD subjects. PMID:24443091

  5. Freestanding single-crystalline magnetic structures fabricated by ion bombardment

    SciTech Connect

    Schoenherr, P.; Bischof, A.; Boehm, B.; Eib, P.; Grimm, S.; Gross, L.; Allenspach, R.; Alvarado, S. F.

    2015-01-19

    Starting from an ultrathin Fe film grown epitaxially on top of a GaAs(001) substrate, we show that freestanding structures can be created by ion-beam treatment. These structures are single-crystalline blisters and only a few nanometers thick. Anisotropic stress in the rim of a blister induces magnetic domain states magnetized in the direction normal to the blister edge. Experimental evidence is provided that the lateral size can be confined by starting from a nanostructured template.

  6. Manipulation by exchange coupling in layered magnetic structures

    SciTech Connect

    Moskalenko, M. A.; Uzdin, V. M.; Zabel, H.

    2014-02-07

    Exchange coupling in magnetic heterostructures can be modified via introduction of additional magnetic spacer layers at the interfaces. The magnetic characteristics and the spacer layer thickness determine the functional properties of the whole system. We show that the hysteresis loop area of trilayer spring magnets with two different soft magnetic layers (s1, s2) and one hard magnetic layer (h) with the sequence s1/s2/h can be increased as compared to both bilayer structures s1/h and s2/h with the same total thickness of the soft layers and for definite thickness ratios of the soft layers and their sequences. For ferrimagnetic spin valves, the perpendicular exchange bias effect can be tuned via the thickness of non-magnetic spacer layers at the interface, which determine the exchange coupling between ferrimagnets. A simple quasi one-dimensional phenomenological model is able to describe the magnetic hysteresis of even complex layered structures and to predict optimal geometrical and magnetic parameters of such heterostructures.

  7. Imaging magnetic structures with a transmission X-ray microscope

    NASA Astrophysics Data System (ADS)

    Fischer, P.; Eimüller, T.; Schütz, G.; Guttmann, P.; Schmahl, G.; Bayreuther, G.

    2000-05-01

    The X-ray magnetic circular dichroism (X-MCD), i.e., the dependence of the absorption of circularly polarized X-rays on the magnetization of the absorber exhibits at L-edges of transition metals values up to 25%. This can serve as a huge magnetic contrast mechanism in combination with a transmission X-ray microscope (TXM) to image magnetic domains providing a lateral resolution down to about 30 nm. The inherent element-specificity, the possibility to record images in varying external fields within a complete hysteresis loop, the relation of the contrast to local magnetic spin and orbital moments, etc. demonstrate the unique applicability to study the magnetic domain structure in current technical relevant systems like magneto-optics for high density storage media, multilayers for GMR applications or nanostructures for MRAM technology.

  8. Two-dimensional chiral asymmetry in unidirectional magnetic anisotropy structures

    NASA Astrophysics Data System (ADS)

    Perna, P.; Ajejas, F.; Maccariello, D.; Cuñado, J. L.; Guerrero, R.; Niño, M. A.; Muñoz, M.; Prieto, J. L.; Miranda, R.; Camarero, J.

    2016-05-01

    We investigate the symmetry-breaking effects of magnetic nanostructures that present unidirectional (one-fold) magnetic anisotropy. Angular and field dependent transport and magnetic properties have been studied in two different exchange-biased systems, i.e. ferromagnetic (FM)/ antiferromagnetic (AFM) bilayer and spin-valve structures. We experimentally show the direct relationships between the magnetoresistance (MR) response and the magnetization reversal pathways for any field value and direction. We demonstrate that even though the MR signals are related to different transport phenomena, namely anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR), chiral asymmetries are found around the magnetization hard-axis direction, in both cases originated from the one-fold symmetry of the interfacial exchange coupling. Our results indicate that the chiral asymmetry of transport and magnetic behaviors are intrinsic of systems with an unidirectional contribution.

  9. Applied DC magnetic fields cause alterations in the time of cell divisions and developmental abnormalities in early sea urchin embryos

    SciTech Connect

    Levin, M.; Ernst, S.G.

    1997-05-01

    Most work on magnetic field effects focuses on AC fields. The present study demonstrates that exposure to medium-strength (10 mT--0.1 T) static magnetic fields can alter the early embryonic development of two species of sea urchin embryos. Batches of fertilized eggs from two species of urchin were exposed to fields produced by permanent magnets. Samples of the continuous cultures were scored for the timing of the first two cell divisions, time of hatching, and incidence of exogastrulation. It was found that static fields delay the onset of mitosis in both species by an amount dependent on the exposure timing relative to fertilization. The exposure time that caused the maximum effect differed between the two species. Thirty millitesla fields, but not 15 mT fields, caused an eightfold increase in the incidence of exogastrulation in Lytechinus pictus, whereas neither of these fields produced exogastrulation in Strongylocentrotus purpuratus.

  10. Abnormal centrosomal structure and duplication in Cep135-deficient vertebrate cells.

    PubMed

    Inanç, Burcu; Pütz, Monika; Lalor, Pierce; Dockery, Peter; Kuriyama, Ryoko; Gergely, Fanni; Morrison, Ciaran G

    2013-09-01

    Centrosomes are key microtubule-organizing centers that contain a pair of centrioles, conserved cylindrical, microtubule-based structures. Centrosome duplication occurs once per cell cycle and relies on templated centriole assembly. In many animal cells this process starts with the formation of a radially symmetrical cartwheel structure. The centrosomal protein Cep135 localizes to this cartwheel, but its role in vertebrates is not well understood. Here we examine the involvement of Cep135 in centriole function by disrupting the Cep135 gene in the DT40 chicken B-cell line. DT40 cells that lack Cep135 are viable and show no major defects in centrosome composition or function, although we note a small decrease in centriole numbers and a concomitant increase in the frequency of monopolar spindles. Furthermore, electron microscopy reveals an atypical structure in the lumen of Cep135-deficient centrioles. Centrosome amplification after hydroxyurea treatment increases significantly in Cep135-deficient cells, suggesting an inhibitory role for the protein in centrosome reduplication during S-phase delay. We propose that Cep135 is required for the structural integrity of centrioles in proliferating vertebrate cells, a role that also limits centrosome amplification in S-phase-arrested cells.

  11. Structural, energetic, and dynamic insights into the abnormal xylene separation behavior of hierarchical porous crystal

    PubMed Central

    Lin, Jiao-Min; He, Chun-Ting; Liao, Pei-Qin; Lin, Rui-Biao; Zhang, Jie-Peng

    2015-01-01

    Separation of highly similar molecules and understanding the underlying mechanism are of paramount theoretical and practical importance, but visualization of the host-guest structure, energy, or dynamism is very difficult and many details have been overlooked. Here, we report a new porous coordination polymer featuring hierarchical porosity and delicate flexibility, in which the three structural isomers of xylene (also similar disubstituted benzene derivatives) can be efficiently separated with an elution sequence inversed with those for conventional mechanisms. More importantly, the separation mechanism is comprehensively and quantitatively visualized by single-crystal X-ray crystallography coupled with multiple computational simulation methods, in which the small apertures not only fit best the smallest para-isomer like molecular sieves, but also show seemingly trivial yet crucial structural alterations to distinguish the meta- and ortho-isomers via a gating mechanism, while the large channels allow fast guest diffusion and enable the structural/energetic effects to be accumulated in the macroscopic level. PMID:26113287

  12. Co-Localisation of Abnormal Brain Structure and Function in Specific Language Impairment

    ERIC Educational Resources Information Center

    Badcock, Nicholas A.; Bishop, Dorothy V. M.; Hardiman, Mervyn J.; Barry, Johanna G.; Watkins, Kate E.

    2012-01-01

    We assessed the relationship between brain structure and function in 10 individuals with specific language impairment (SLI), compared to six unaffected siblings, and 16 unrelated control participants with typical language. Voxel-based morphometry indicated that grey matter in the SLI group, relative to controls, was increased in the left inferior…

  13. Model for dynamic self-assembled magnetic surface structures

    NASA Astrophysics Data System (ADS)

    Belkin, M.; Glatz, A.; Snezhko, A.; Aranson, I. S.

    2010-07-01

    We propose a first-principles model for the dynamic self-assembly of magnetic structures at a water-air interface reported in earlier experiments. The model is based on the Navier-Stokes equation for liquids in shallow water approximation coupled to Newton equations for interacting magnetic particles suspended at a water-air interface. The model reproduces most of the observed phenomenology, including spontaneous formation of magnetic snakelike structures, generation of large-scale vortex flows, complex ferromagnetic-antiferromagnetic ordering of the snake, and self-propulsion of bead-snake hybrids.

  14. Model for dynamic self-assembled magnetic surface structures.

    SciTech Connect

    Belkin, M.; Glatz, A.; Snezhko, A.; Aranson, I. S.; Materials Science Division; Northwestern Univ.

    2010-07-07

    We propose a first-principles model for the dynamic self-assembly of magnetic structures at a water-air interface reported in earlier experiments. The model is based on the Navier-Stokes equation for liquids in shallow water approximation coupled to Newton equations for interacting magnetic particles suspended at a water-air interface. The model reproduces most of the observed phenomenology, including spontaneous formation of magnetic snakelike structures, generation of large-scale vortex flows, complex ferromagnetic-antiferromagnetic ordering of the snake, and self-propulsion of bead-snake hybrids.

  15. Abnormal temporal and parietal magnetic activations during the early stages of theory of mind in schizophrenic patients.

    PubMed

    Vistoli, Damien; Brunet-Gouet, Eric; Lemoalle, Amelia; Hardy-Baylé, Marie-Christine; Passerieux, Christine

    2011-01-01

    Schizophrenia is associated with abnormal cortical activation during theory of mind (ToM), as demonstrated by several fMRI or PET studies. Electrical and temporal characteristics of these abnormalities, especially in the early stages, remain unexplored. Nineteen medicated schizophrenic patients and 21 healthy controls underwent magnetoencephalography (MEG) recording to measure brain response evoked by nonverbal stimuli requiring mentalizing. Three conditions based on comic-strips were contrasted: attribution of intentions to others (AI), physical causality with human characters (PCCH), and physical causality with objects (PCOB). Minimum norm localization was performed in order to select regions of interest (ROIs) within bilateral temporal and parietal regions that showed significant ToM-related activations in the control group. Time-courses of each ROI were compared across group and condition. Reduced cortical activation within the 200 to 600 ms time-window was observed in the selected regions in patients. Significant group by condition interactions (i.e., reduced modulation in patients) were found in right posterior superior temporal sulcus, right temporoparietal junction, and right inferior parietal lobule during attribution of intentions. As in healthy controls, the presence of characters elicited activation in patients' left posterior temporal regions and temporoparietal junction. No group difference on evoked responses' latencies in AI was found. In conclusion, ToM processes in the early stages are functionally impaired in schizophrenia. MEG provides a promising means to refine our knowledge on schizophrenic social cognitive disorders.

  16. Structural brain abnormalities in patients with Parkinson's disease with visual hallucinations: a comparative voxel-based analysis.

    PubMed

    Gama, Romulo Lopes; Bruin, Veralice Meireles Sales; Távora, Daniel Gurgel Fernandes; Duran, Fábio L S; Bittencourt, Lia; Tufik, Sergio

    2014-06-01

    The objective is to evaluate clinical characteristics and cerebral alterations in Parkinson's disease (PD) patients with diurnal visual hallucinations (VHs). Assessment was performed using magnetic resonance image (MRI) and voxel-based morphometry (VBM). Thirty-nine patients with PD (53.8%) and ten controls were studied. Voxel based morphology analysis was performed. Eleven patients presented diurnal VHs and among these, six had cognitive dysfunction. Patients with VHs performed worse in the mentation-related UPDRS I (p=0.005) and motor-related UPDRS III (p=0.02). Patients with VHs showed significant clusters of reduced grey matter volume compared to controls in the left opercula frontal gyrus and left superior frontal gyrus. PD without hallucinations demonstrated reduced grey matter volume in the left superior frontal gyrus compared to controls. Comparisons between patients with VHs regarding the presence of cognitive dysfunction showed that cases with cognitive dysfunction as compared to those without cognitive dysfunction showed significant clusters of reduced grey matter volume in the left opercular frontal gyrus. Cases without cognitive dysfunction had reduced grey matter substance in the left insula and left trigonal frontal gyrus. Judging from our findings, an abnormal frontal cortex, particularly left sided insula, frontal opercular, trigonal frontal gyrus and orbital frontal would make PD patients vulnerable to hallucinations. Compromise of the left operculum distinguished cases with VHs and cognitive dysfunction. Our findings reinforce the theoretical concept of a top-down visual processing in the genesis of VHs in PD.

  17. Structure-fluctuation-induced abnormal thermoelectric properties in semiconductor copper selenide

    SciTech Connect

    Liu, Huili; Shi, Xun; Kirkham, Melanie J; Wang, Hsin; Li, Qiang; Uher, Ctirad; Zhang, Wenqing; Chen, Lidong

    2013-01-01

    Thermoelectric effects and related technologies have attracted a great interest due to the world-wide energy harvesting. Thermoelectricity has usually been considered in the context of stable material phases. Here we report that the fluctuation of structures during the second-order phase transition in Cu2Se semiconductor breaks the conventional trends of thermoelectric transports in normal phases, leading to a critically phase-transition-enhanced thermoelectric figure of merit zT above unity at 400K, a three times larger value than for the normal phases. Dynamic structural transformations introduce intensive fluctuations and extreme complexity, which enhance the carrier entropy and thus the thermopower, and strongly scatter carriers and phonons as well to make their transports behave critically.

  18. Large-scale brain network abnormalities in Huntington's disease revealed by structural covariance.

    PubMed

    Minkova, Lora; Eickhoff, Simon B; Abdulkadir, Ahmed; Kaller, Christoph P; Peter, Jessica; Scheller, Elisa; Lahr, Jacob; Roos, Raymund A; Durr, Alexandra; Leavitt, Blair R; Tabrizi, Sarah J; Klöppel, Stefan

    2016-01-01

    Huntington's disease (HD) is a progressive neurodegenerative disorder that can be diagnosed with certainty decades before symptom onset. Studies using structural MRI have identified grey matter (GM) loss predominantly in the striatum, but also involving various cortical areas. So far, voxel-based morphometric studies have examined each brain region in isolation and are thus unable to assess the changes in the interrelation of brain regions. Here, we examined the structural covariance in GM volumes in pre-specified motor, working memory, cognitive flexibility, and social-affective networks in 99 patients with manifest HD (mHD), 106 presymptomatic gene mutation carriers (pre-HD), and 108 healthy controls (HC). After correction for global differences in brain volume, we found that increased GM volume in one region was associated with increased GM volume in another. When statistically comparing the groups, no differences between HC and pre-HD were observed, but increased positive correlations were evident for mHD, relative to pre-HD and HC. These findings could be explained by a HD-related neuronal loss heterogeneously affecting the examined network at the pre-HD stage, which starts to dominate structural covariance globally at the manifest stage. Follow-up analyses identified structural connections between frontoparietal motor regions to be linearly modified by disease burden score (DBS). Moderator effects of disease load burden became significant at a DBS level typically associated with the onset of unequivocal HD motor signs. Together with existing findings from functional connectivity analyses, our data indicates a critical role of these frontoparietal regions for the onset of HD motor signs.

  19. Histological investigation of the supra-glottal structures in humans for understanding abnormal phonation

    NASA Astrophysics Data System (ADS)

    Kimura, Miwako; Sakakibara, Ken-Ichi; Imagawa, Hiroshi; Chan, Roger; Niimi, Seijii; Tayama, Niro

    2002-11-01

    Phonation is the vocal fold vibration on normal voice. But sometimes we can observe the other phonation styles like as the pressed voice or some throat singings like as ''kargyraa'' or ''drone'' in Khoomei in Mongolian music. Also, clinically, we know that some patients who have the wide glottal slit in phonation because of the recurrence nerve palsy or after partial laryngectomy, could make the ''supra-glottal phonation.'' The ''supra-glottal phonation'' would be made from the vibration of ''supra-glottal structures'' such as the false vocal folds, the arytenoids and the epiglottis, etc. Endoscopic examination suggests the existence of some contractile functions in supra-glottal space. However, these phonation systems have not been clear to explain their neuromuscular mechanism in histology. This study aimed to find the basis for making the supra-glottal phonation from the points of view of the histological structures. We tried to investigate if there were any muscles that could contract the supra-glottal structures. The samples are the excised larynx of human beings. They were fixed by formalin after excision. We observed their macroscopic anatomy, and also with the microscopic observation their histological preparations after the process of the embedding in paraffin, slicing for the preparation and HE (hematoxylin-eosin) staining.

  20. Structure and magnetism in novel group IV element-based magnetic materials

    SciTech Connect

    Tsui, Frank

    2013-08-14

    The project is to investigate structure, magnetism and spin dependent states of novel group IV element-based magnetic thin films and heterostructures as a function of composition and epitaxial constraints. The materials systems of interest are Si-compatible epitaxial films and heterostructures of Si/Ge-based magnetic ternary alloys grown by non-equilibrium molecular beam epitaxy (MBE) techniques, specifically doped magnetic semiconductors (DMS) and half-metallic Heusler alloys. Systematic structural, chemical, magnetic, and electrical measurements are carried out, using x-ray microbeam techniques, magnetotunneling spectroscopy and microscopy, and magnetotransport. The work is aimed at elucidating the nature and interplay between structure, chemical order, magnetism, and spin-dependent states in these novel materials, at developing materials and techniques to realize and control fully spin polarized states, and at exploring fundamental processes that stabilize the epitaxial magnetic nanostructures and control the electronic and magnetic states in these complex materials. Combinatorial approach provides the means for the systematic studies, and the complex nature of the work necessitates this approach.

  1. Prevalence of X-aneuploidies, X-structural abnormalities and 46,XY sex reversal in Turkish women with primary amenorrhea or premature ovarian insufficiency.

    PubMed

    Geckinli, B B; Toksoy, G; Sayar, C; Soylemez, M A; Yesil, G; Aydın, H; Karaman, A; Devranoglu, B

    2014-11-01

    Our objective was to identify the distribution of cytogenetic abnormalities of 175 Turkish women with primary amenorrhea (PA) or premature ovarian insufficiency (POI). A retrospective study was performed using medical records of 94 patients with PA and 81 patients with POI at the Genetics Department, Zeynep Kamil Women's and Children's Research and Training Hospital, Istanbul, Turkey. G-banded metaphase karyotype analysis were prepared and analyzed. Chromosomal abnormalities were present in 44 of 175 cases (25%). 15 were full blown or mosaic numerical X chromosome abnormalities (8.5%), 10 were full blown or mosaic X-chromosome structural anomalies (5.7%), one was X-autosome translocation (0.5%), 3 were autosomal anomalies (1.7%), 12 were XY karyotype (6.8%), one was 45,X/46,XY mosaic and 2 were full blown or mosaic structural anomalies of Y chromosome (1.7%). The prevalence of chromosomal abnormalities was 25% in this large series of Turkish women with primary amenorrhea or premature ovarian insufficiency, most cases involving X-aneuploidy or X-structural abnormalities or 46,XY karyotype. High prevalence of chromosomal abnormalities is associated with POI starting at an early age (average age: 26 years).

  2. Magnetic anisotropy and magnetic domain structure in C-doped Mn5Ge3

    NASA Astrophysics Data System (ADS)

    Michez, L.-A.; Virot, F.; Petit, M.; Hayn, R.; Notin, L.; Fruchart, O.; Heresanu, V.; Jamet, M.; Le Thanh, V.

    2015-07-01

    Magnetic properties of Mn5Ge3C0.7 thin films grown by molecular beam epitaxy have been studied. SQUID-VSM measurements and magnetic force microscopy have been used to probe the magnetic state and determine the relevant magnetic parameters. The results are supported by a combination of improved Saito's and Kittel's models. The moderate perpendicular magnetic anisotropy ( Qe x p=2/Ku μ0MSa t 2 ≈0.2 ) leads to a stripe domain structure for film thicknesses above 28 nm. For thinner films, the magnetization lies in-plane. The uniaxial magnetocrystalline constant has been found to be much weaker than in Mn5Ge3 and is assigned to hybridization effect between the Mn and C atoms.

  3. X-ray diffraction microscopy of magnetic structures.

    PubMed

    Turner, Joshua J; Huang, Xiaojing; Krupin, Oleg; Seu, Keoki A; Parks, Daniel; Kevan, Stephen; Lima, Enju; Kisslinger, Kim; McNulty, Ian; Gambino, Richard; Mangin, Stephane; Roy, Sujoy; Fischer, Peter

    2011-07-15

    We report the first proof-of-principle experiment of iterative phase retrieval from magnetic x-ray diffraction. By using the resonant x-ray excitation process and coherent x-ray scattering, we show that linearly polarized soft x rays can be used to image both the amplitude and the phase of magnetic domain structures. We recovered the magnetic structure of an amorphous terbium-cobalt thin film with a spatial resolution of about 75 nm at the Co L3 edge at 778 eV. In comparison with soft x-ray microscopy images recorded with Fresnel zone plate optics at better than 25 nm spatial resolution, we find qualitative agreement in the observed magnetic structure.

  4. X-Ray Diffraction Microscopy of Magnetic Structures

    SciTech Connect

    Turner, J.; Lima, E.; Huang, X.; Krupin, O.; Seu, K.; Parks, D.; Kevan, S.; Kisslinger, K.; McNulty, I.; Gambino, R.; Mangin, S.; Roy, S. and Fischer, P.

    2011-07-14

    We report the first proof-of-principle experiment of iterative phase retrieval from magnetic x-ray diffraction. By using the resonant x-ray excitation process and coherent x-ray scattering, we show that linearly polarized soft x rays can be used to image both the amplitude and the phase of magnetic domain structures. We recovered the magnetic structure of an amorphous terbium-cobalt thin film with a spatial resolution of about 75 nm at the Co L{sub 3} edge at 778 eV. In comparison with soft x-ray microscopy images recorded with Fresnel zone plate optics at better than 25 nm spatial resolution, we find qualitative agreement in the observed magnetic structure.

  5. Craniofacial Abnormalities

    MedlinePlus

    ... of the skull and face. Craniofacial abnormalities are birth defects of the face or head. Some, like cleft ... palate, are among the most common of all birth defects. Others are very rare. Most of them affect ...

  6. Chromosome Abnormalities

    MedlinePlus

    ... decade, newer techniques have been developed that allow scientists and doctors to screen for chromosomal abnormalities without using a microscope. These newer methods compare the patient's DNA to a normal DNA ...

  7. Walking abnormalities

    MedlinePlus

    ... include: Arthritis of the leg or foot joints Conversion disorder (a psychological disorder) Foot problems (such as a ... injuries. For an abnormal gait that occurs with conversion disorder, counseling and support from family members are strongly ...

  8. Nail abnormalities

    MedlinePlus

    Beau's lines; Fingernail abnormalities; Spoon nails; Onycholysis; Leukonychia; Koilonychia; Brittle nails ... Just like the skin, the fingernails tell a lot about your health: ... the fingernail. These lines can occur after illness, injury to ...

  9. Synthesis, structure and magnetism in copper chalcochromite spinels

    NASA Astrophysics Data System (ADS)

    Neulinger, Janell Rebecca

    The copper chalcochromites (CuCr2X4 (X = S, Se, Te)) possess a rare combination of magnetic and electronic properties compared to other chalcogenide spinet materials. A precise structural and magnetic investigation of these materials was undertaken in order to facilitate technological exploitation of these unusual properties. CuCr2Se4, several halogenated derivatives of the form CuCr2Se4 -xXx (with X = Cl, Br, or I), and CuCr2S3Cl were prepared via powder methods and chemical vapor transport growth of single crystals. A variety of X-ray diffraction techniques were employed to determine the crystal structures of the synthesis products. The materials adopt a trigonal variation of the spinet structure type; the lower-symmetry structure includes a single threefold roto-inversion axis. Halogen doping introduces systematic changes in the properties of the chalcochromites, and the effects of halogen doping were monitored by magnetometry, soft X-ray spectroscopy, and magnetic microscopy techniques. Bulk magnetic properties were characterized by SQUID and vibrating sample magnetometry, at temperatures from 5 K to above the Curie temperatures. Soft X-ray spectroscopic measurements performed at the Advanced Light Source at Lawrence Berkeley National Laboratory included X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) experiments. Dichroic spectra at the Cr L2,3 and Cu L 2,3 absorption edges confirm a ferrimagnetic model of opposing magnetic sub-lattices localized on the Cr and Cu centers; increasing levels of halogen doping suppress the contribution from the copper sublattice and reduce T C. Magnetic domain imaging using the Photoelectron Electron Microscope (PEEM) at the Advanced Light Source indicates the presence of a variety of domain morphologies, including predominantly stripe domains reflecting the uniaxial symmetry of the trigonal spinel structure. The magnetic and structural features of the copper chalcochromites mark them as robust, tunable, and

  10. Magnetic resonance imaging in partial epilepsy: additional abnormalities shown with the fluid attenuated inversion recovery (FLAIR) pulse sequence.

    PubMed Central

    Bergin, P S; Fish, D R; Shorvon, S D; Oatridge, A; deSouza, N M; Bydder, G M

    1995-01-01

    Thirty six patients with a history of partial epilepsy had MRI of the brain performed with conventional T1 and T2 weighted pulse sequences as well as the fluid attenuated inversion recovery (FLAIR) sequence. Abnormalities were found in 20 cases (56%), in whom there were 25 lesions or groups of lesions. Twenty four of these lesions were more conspicuous with the FLAIR sequence than with any of the conventional sequences. In 11 of these 20 cases, lesions thought to be of aetiological importance were only seen with the FLAIR sequence. In eight this was a solitary lesion. In the other three, an additional and apparently significant lesion (or lesions) was only seen with the FLAIR sequence when another lesion had been identified with both conventional and FLAIR sequences. The 11 additional lesions or groups of lesions were seen in the hippocampus, amygdala, cortex, or subcortical and periventricular regions. No lesion was found with any pulse sequence in 16 (44%) of the original group of 36 patients. In the eight cases where a lesion was seen only with the FLAIR sequence, localisation was concordant with the electroclinical features. Two of the eight patients with solitary lesions seen only on the FLAIR sequence underwent surgery, after which there was pathological confirmation of the abnormality identified with imaging. In one patient with a congenital cavernoma, the primary lesion was best seen with a contrast enhanced T1 weighted spin echo sequence. In this selected series, the FLAIR sequence increased the yield of MRI examinations of the brain by 30%. Images PMID:7738550

  11. Structural Abnormalities in the Hair of a Patient with a Novel Ribosomopathy

    PubMed Central

    Alsop, Richard J.; Soomro, Asfia; Zhang, Yuchen; Pieterse, Marc; Fatona, Ayodele; Dej, Kimberly; Rheinstädter, Maikel C.

    2016-01-01

    We report the biophysical characterization of hair from a patient with a de novo ribosomopathy. The patient was diagnosed with a mutation on gene RPS23, which codes for a protein which comprises part of the 40S subunit of the ribosome. The patient presents with a number of phenotypes, including hypotonia, autism, extra teeth, elastic skin, and thin/brittle hair. We combined optical microscopy, tensile tests, and X-ray diffraction experiments on hair samples obtained from the scalp of the patient to a multi-scale characterization of the hair from macroscopic to molecular length scales and observe distinct differences in the biophysical properties in the patient’s hair when compared to hair from other family members. While no differences were observed in the coiled-coil structure of the keratin proteins or the structure of the intermediate filaments, the patient’s hair was 22% thinner, while the Young’s modulus remained roughly constant. The X-ray diffraction results give evidence that the amount of lipids in the cell membrane complex is reduced by 20%, which well accounts for the other observations. The pathologies characterized by these techniques may be used to inform the diagnosis of similar de novo mutations in the future. PMID:26982655

  12. Structural Abnormalities in the Hair of a Patient with a Novel Ribosomopathy.

    PubMed

    Alsop, Richard J; Soomro, Asfia; Zhang, Yuchen; Pieterse, Marc; Fatona, Ayodele; Dej, Kimberly; Rheinstädter, Maikel C

    2016-01-01

    We report the biophysical characterization of hair from a patient with a de novo ribosomopathy. The patient was diagnosed with a mutation on gene RPS23, which codes for a protein which comprises part of the 40S subunit of the ribosome. The patient presents with a number of phenotypes, including hypotonia, autism, extra teeth, elastic skin, and thin/brittle hair. We combined optical microscopy, tensile tests, and X-ray diffraction experiments on hair samples obtained from the scalp of the patient to a multi-scale characterization of the hair from macroscopic to molecular length scales and observe distinct differences in the biophysical properties in the patient's hair when compared to hair from other family members. While no differences were observed in the coiled-coil structure of the keratin proteins or the structure of the intermediate filaments, the patient's hair was 22% thinner, while the Young's modulus remained roughly constant. The X-ray diffraction results give evidence that the amount of lipids in the cell membrane complex is reduced by 20%, which well accounts for the other observations. The pathologies characterized by these techniques may be used to inform the diagnosis of similar de novo mutations in the future. PMID:26982655

  13. Structural Abnormalities in the Hair of a Patient with a Novel Ribosomopathy.

    PubMed

    Alsop, Richard J; Soomro, Asfia; Zhang, Yuchen; Pieterse, Marc; Fatona, Ayodele; Dej, Kimberly; Rheinstädter, Maikel C

    2016-01-01

    We report the biophysical characterization of hair from a patient with a de novo ribosomopathy. The patient was diagnosed with a mutation on gene RPS23, which codes for a protein which comprises part of the 40S subunit of the ribosome. The patient presents with a number of phenotypes, including hypotonia, autism, extra teeth, elastic skin, and thin/brittle hair. We combined optical microscopy, tensile tests, and X-ray diffraction experiments on hair samples obtained from the scalp of the patient to a multi-scale characterization of the hair from macroscopic to molecular length scales and observe distinct differences in the biophysical properties in the patient's hair when compared to hair from other family members. While no differences were observed in the coiled-coil structure of the keratin proteins or the structure of the intermediate filaments, the patient's hair was 22% thinner, while the Young's modulus remained roughly constant. The X-ray diffraction results give evidence that the amount of lipids in the cell membrane complex is reduced by 20%, which well accounts for the other observations. The pathologies characterized by these techniques may be used to inform the diagnosis of similar de novo mutations in the future.

  14. Symmetry, Structure, and Dynamics of Monoaxial Chiral Magnets

    NASA Astrophysics Data System (ADS)

    Togawa, Yoshihiko; Kousaka, Yusuke; Inoue, Katsuya; Kishine, Jun-ichiro

    2016-11-01

    Nontrivial spin orders with magnetic chirality emerge in a particular class of magnetic materials with structural chirality, which are frequently referred to as chiral magnets. Various interesting physical properties are expected to be induced in chiral magnets through the coupling of chiral magnetic orders with conduction electrons and electromagnetic fields. One promising candidate for achieving these couplings is a chiral spin soliton lattice. Here, we review recent experimental observations mainly carried out on the monoaxial chiral magnetic crystal CrNb3S6 via magnetic imaging using electron, neutron, and X-ray beams and magnetoresistance measurements, together with the strategy for synthesizing chiral magnetic materials and underlying theoretical backgrounds. The chiral soliton lattice appears under a magnetic field perpendicular to the chiral helical axis and is very robust and stable with phase coherence on a macroscopic length scale. The tunable and topological nature of the chiral soliton lattice gives rise to nontrivial physical properties. Indeed, it is demonstrated that the interlayer magnetoresistance scales to the soliton density, which plays an essential role as an order parameter in chiral soliton lattice formation, and becomes quantized with the reduction of the system size. These interesting features arising from macroscopic phase coherence unique to the chiral soliton lattice will lead to the exploration of routes to a new paradigm for applications in spin electronics using spin phase coherence.

  15. Does abnormal glycogen structure contribute to increased susceptibility to seizures in epilepsy?

    PubMed

    DiNuzzo, Mauro; Mangia, Silvia; Maraviglia, Bruno; Giove, Federico

    2015-02-01

    Epilepsy is a family of brain disorders with a largely unknown etiology and high percentage of pharmacoresistance. The clinical manifestations of epilepsy are seizures, which originate from aberrant neuronal synchronization and hyperexcitability. Reactive astrocytosis, a hallmark of the epileptic tissue, develops into loss-of-function of glutamine synthetase, impairment of glutamate-glutamine cycle and increase in extracellular and astrocytic glutamate concentration. Here, we argue that chronically elevated intracellular glutamate level in astrocytes is instrumental to alterations in the metabolism of glycogen and leads to the synthesis of polyglucosans. Unaccessibility of glycogen-degrading enzymes to these insoluble molecules compromises the glycogenolysis-dependent reuptake of extracellular K(+) by astrocytes, thereby leading to increased extracellular K(+) and associated membrane depolarization. Based on current knowledge, we propose that the deterioration in structural homogeneity of glycogen particles is relevant to disruption of brain K(+) homeostasis and increased susceptibility to seizures in epilepsy.

  16. Structural, Metabolic, and Functional Brain Abnormalities as a Result of Prenatal Exposure to Drugs of Abuse: Evidence from Neuroimaging

    PubMed Central

    Roussotte, Florence; Soderberg, Lindsay

    2010-01-01

    Prenatal exposure to alcohol and stimulants negatively affects the developing trajectory of the central nervous system in many ways. Recent advances in neuroimaging methods have allowed researchers to study the structural, metabolic, and functional abnormalities resulting from prenatal exposure to drugs of abuse in living human subjects. Here we review the neuroimaging literature of prenatal exposure to alcohol, cocaine, and methamphetamine. Neuroimaging studies of prenatal alcohol exposure have reported differences in the structure and metabolism of many brain systems, including in frontal, parietal, and temporal regions, in the cerebellum and basal ganglia, as well as in the white matter tracts that connect these brain regions. Functional imaging studies have identified significant differences in brain activation related to various cognitive domains as a result of prenatal alcohol exposure. The published literature of prenatal exposure to cocaine and methamphetamine is much smaller, but evidence is beginning to emerge suggesting that exposure to stimulant drugs in utero may be particularly toxic to dopamine-rich basal ganglia regions. Although the interpretation of such findings is somewhat limited by the problem of polysubstance abuse and by the difficulty of obtaining precise exposure histories in retrospective studies, such investigations provide important insights into the effects of drugs of abuse on the structure, function, and metabolism of the developing human brain. These insights may ultimately help clinicians develop better diagnostic tools and devise appropriate therapeutic interventions to improve the condition of children with prenatal exposure to drugs of abuse. PMID:20978945

  17. Abnormalities in the basement membrane structure promote basal keratinocytes in the epidermis of hypertrophic scars to adopt a proliferative phenotype.

    PubMed

    Yang, Shaowei; Sun, Yexiao; Geng, Zhijun; Ma, Kui; Sun, Xiaoyan; Fu, Xiaobing

    2016-05-01

    The majority of studies on scar formation have mainly focused on the dermis and little is known of the involvement of the epidermis. Previous research has demonstrated that the scar tissue-derived keratinocytes are different from normal cells at both the genetic and cell biological levels; however, the mechanisms responsible for the fundamental abnormalities in keratinocytes during scar development remain elusive. For this purpose, in this study, we used normal, wound edge and hypertrophic scar tissue to examine the morphological changes which occur during epidermal regeneration as part of the wound healing process and found that the histological structure of hypertrophic scar tissues differed from that of normal skin, with a significant increase in epidermal thickness. Notably, staining of the basement membrane (BM) appeared to be absent in the scar tissues. Moreover, immunofluorescence staining for cytokeratin (CK)10, CK14, CK5, CK19 and integrin-β1 indicated the differential expression of cell markers in the epidermal keratinocytes among the normal, wound edge and hypertrophic scar tissues, which corresponded with the altered BM structures. By using a panel of proteins associated with BM components, we validated our hypothesis that the BM plays a significant role in regulating the cell fate decision of epidermal keratinocytes during skin wound healing. Alterations in the structure of the BM promote basal keratinocytes to adopt a proliferative phenotype both in vivo and in vitro.

  18. Magnetically Controlled Structures in the Ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Duru, F.; Gurnett, D. A.; Averkamp, T. F.; Kirchner, D. L.; Huff, R. L.; Persoon, A. M.; Plaut, J. J.; Picardi, G.

    2006-12-01

    The ionospheric sounding data obtained by the MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) instrument on the Mars Express spacecraft show that the dayside ionosphere has considerable structure over regions of strong crustal magnetic fields. This structure is typically seen as a hyperbola-shaped trace in a display of echo intensity versus apparent altitude and time. The hyperbola shapes are consistent with oblique reflections from regions of enhanced electron density that are fixed with respect to Mars. Comparisons with the Cain et al. [2003] model for the crustal magnetic field of Mars show that the apexes of the hyperbolas, which identify the closest approach to the regions of enhanced electron density, usually coincide with regions where the crustal magnetic field is strong and nearly vertical. The electron density enhancements, which extend as much as 50 km above the surrounding ionosphere, are believed to arise from increases in the scale height of the ionosphere, possibly due to heating of the ionosphere by solar wind electrons that reach the base of the ionosphere along the nearly vertical (open) magnetic field lines. Statistical analyses of the apparent altitudes of the apexes of the hyperbolas, as well as analyses of repeated passes over the same region, indicate that the electron density enhancements usually consist of horizontal cylinder-like structures rather than isolated hemispherical structures. In many cases the axes of the cylindrical density structures are aligned with the symmetry axes of adjacent cylindrical magnetic field structures with opposite polarity.

  19. Magnetically controlled structures in the ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Duru, F.; Gurnett, D. A.; Averkamp, T. F.; Kirchner, D. L.; Huff, R. L.; Persoon, A. M.; Plaut, J. J.; Picardi, G.

    2006-12-01

    The ionospheric sounding data obtained by the MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) instrument on the Mars Express spacecraft show that the dayside ionosphere has considerable structure over regions of strong crustal magnetic fields. This structure is typically seen as a hyperbola-shaped trace in a display of echo intensity versus apparent altitude and time. The hyperbola shapes are consistent with oblique reflections from regions of enhanced electron density that are fixed with respect to Mars. Comparisons with the Cain et al. (2003) model for the crustal magnetic field of Mars show that the apexes of the hyperbolas, which identify the closest approach to the regions of enhanced electron density, usually coincide with regions where the crustal magnetic field is strong and nearly vertical. The electron density enhancements, which extend as much as 50 km above the surrounding ionosphere, are believed to arise from increases in the scale height of the ionosphere, possibly due to heating of the ionosphere by solar wind electrons that reach the base of the ionosphere along the nearly vertical (open) magnetic field lines. Statistical analyses of the apparent altitudes of the apexes of the hyperbolas, as well as analyses of repeated passes over the same region, indicate that the electron density enhancements usually consist of horizontal cylinder-like structures rather than isolated hemispherical structures. In many cases the axes of the cylindrical density structures are aligned with the symmetry axes of adjacent cylindrical magnetic field structures with opposite polarity.

  20. Diffusion magnetic resonance imaging study of schizophrenia in the context of abnormal neurodevelopment using multiple site data in a Chinese Han population.

    PubMed

    Li, Y; Xie, S; Liu, B; Song, M; Chen, Y; Li, P; Lu, L; Lv, L; Wang, H; Yan, H; Yan, J; Zhang, H; Zhang, D; Jiang, T

    2016-01-19

    Schizophrenia has increasingly been considered a neurodevelopmental disorder, and the advancement of neuroimaging techniques and associated computational methods has enabled quantitative re-examination of this important theory on the pathogenesis of the disease. Inspired by previous findings from neonatal brains, we proposed that an increase in diffusion magnetic resonance imaging (dMRI) mean diffusivity (MD) should be observed in the cerebral cortex of schizophrenia patients compared with healthy controls, corresponding to lower tissue complexity and potentially a failure to reach cortical maturation. We tested this hypothesis using dMRI data from a Chinese Han population comprising patients from four different hospital sites. Utilizing data-driven methods based on the state-of-the-art tensor-based registration algorithm, significantly increased MD measurements were consistently observed in the cortex of schizophrenia patients across all four sites, despite differences in psychopathology, exposure to antipsychotic medication and scanners used for image acquisition. Specifically, we found increased MD in the limbic system of the schizophrenic brain, mainly involving the bilateral insular and prefrontal cortices. In light of the existing literature, we speculate that this may represent a neuroanatomical signature of the disorder, reflecting microstructural deficits due to developmental abnormalities. Our findings not only provide strong support to the abnormal neurodevelopment theory of schizophrenia, but also highlight an important neuroimaging endophenotype for monitoring the developmental trajectory of high-risk subjects of the disease, thereby facilitating early detection and prevention.

  1. An in vivo and in vitro H-magnetic resonance spectroscopy study of mdx mouse brain: abnormal development or neural necrosis?

    PubMed

    Tracey, I; Dunn, J F; Parkes, H G; Radda, G K

    1996-09-15

    Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder primarily affecting young boys, often causing mental retardation in addition to the well-known progressive muscular weakness. Normal dystrophin expression is lacking in skeletal muscle and the central nervous system (CNS) of both DMD children and the mdx mouse model. The underlying biochemical lesion causing mental impairment in DMD is unknown. 1H-magnetic resonance spectroscopy (1H-MRS) detects choline-containing compounds, creatine and N-acetyl aspartate (NAA) in vivo. NAA is commonly used as a chemical marker for neurons, and a decline in NAA is thought to correlate with neuronal loss. Control mice were compared to mdx using a combination of in vivo and in vitro 1H-MRS methods to determine whether neural necrosis or developmental abnormalities occur in dystrophic brain. NAA levels were normal in mdx brain compared to controls suggesting minor, if any, neuronal necrosis in dystrophic brain. In contrast, choline compounds and myo-inositol levels were increased, indicative of gliosis or developmental abnormalities in dystrophic brain. PMID:8880686

  2. Diffusion magnetic resonance imaging study of schizophrenia in the context of abnormal neurodevelopment using multiple site data in a Chinese Han population

    PubMed Central

    Li, Y; Xie, S; Liu, B; Song, M; Chen, Y; Li, P; Lu, L; Lv, L; Wang, H; Yan, H; Yan, J; Zhang, H; Zhang, D; Jiang, T

    2016-01-01

    Schizophrenia has increasingly been considered a neurodevelopmental disorder, and the advancement of neuroimaging techniques and associated computational methods has enabled quantitative re-examination of this important theory on the pathogenesis of the disease. Inspired by previous findings from neonatal brains, we proposed that an increase in diffusion magnetic resonance imaging (dMRI) mean diffusivity (MD) should be observed in the cerebral cortex of schizophrenia patients compared with healthy controls, corresponding to lower tissue complexity and potentially a failure to reach cortical maturation. We tested this hypothesis using dMRI data from a Chinese Han population comprising patients from four different hospital sites. Utilizing data-driven methods based on the state-of-the-art tensor-based registration algorithm, significantly increased MD measurements were consistently observed in the cortex of schizophrenia patients across all four sites, despite differences in psychopathology, exposure to antipsychotic medication and scanners used for image acquisition. Specifically, we found increased MD in the limbic system of the schizophrenic brain, mainly involving the bilateral insular and prefrontal cortices. In light of the existing literature, we speculate that this may represent a neuroanatomical signature of the disorder, reflecting microstructural deficits due to developmental abnormalities. Our findings not only provide strong support to the abnormal neurodevelopment theory of schizophrenia, but also highlight an important neuroimaging endophenotype for monitoring the developmental trajectory of high-risk subjects of the disease, thereby facilitating early detection and prevention. PMID:26784969

  3. Diffusion magnetic resonance imaging study of schizophrenia in the context of abnormal neurodevelopment using multiple site data in a Chinese Han population.

    PubMed

    Li, Y; Xie, S; Liu, B; Song, M; Chen, Y; Li, P; Lu, L; Lv, L; Wang, H; Yan, H; Yan, J; Zhang, H; Zhang, D; Jiang, T

    2016-01-01

    Schizophrenia has increasingly been considered a neurodevelopmental disorder, and the advancement of neuroimaging techniques and associated computational methods has enabled quantitative re-examination of this important theory on the pathogenesis of the disease. Inspired by previous findings from neonatal brains, we proposed that an increase in diffusion magnetic resonance imaging (dMRI) mean diffusivity (MD) should be observed in the cerebral cortex of schizophrenia patients compared with healthy controls, corresponding to lower tissue complexity and potentially a failure to reach cortical maturation. We tested this hypothesis using dMRI data from a Chinese Han population comprising patients from four different hospital sites. Utilizing data-driven methods based on the state-of-the-art tensor-based registration algorithm, significantly increased MD measurements were consistently observed in the cortex of schizophrenia patients across all four sites, despite differences in psychopathology, exposure to antipsychotic medication and scanners used for image acquisition. Specifically, we found increased MD in the limbic system of the schizophrenic brain, mainly involving the bilateral insular and prefrontal cortices. In light of the existing literature, we speculate that this may represent a neuroanatomical signature of the disorder, reflecting microstructural deficits due to developmental abnormalities. Our findings not only provide strong support to the abnormal neurodevelopment theory of schizophrenia, but also highlight an important neuroimaging endophenotype for monitoring the developmental trajectory of high-risk subjects of the disease, thereby facilitating early detection and prevention. PMID:26784969

  4. Abnormalities in brain structure and behavior in GSK-3alpha mutant mice

    PubMed Central

    2009-01-01

    Background Glycogen synthase kinase-3 (GSK-3) is a widely expressed and highly conserved serine/threonine protein kinase encoded by two genes that generate two related proteins: GSK-3α and GSK-3β. Mice lacking a functional GSK-3α gene were engineered in our laboratory; they are viable and display insulin sensitivity. In this study, we have characterized brain functions of GSK-3α KO mice by using a well-established battery of behavioral tests together with neurochemical and neuroanatomical analysis. Results Similar to the previously described behaviours of GSK-3β+/-mice, GSK-3α mutants display decreased exploratory activity, decreased immobility time and reduced aggressive behavior. However, genetic inactivation of the GSK-3α gene was associated with: decreased locomotion and impaired motor coordination, increased grooming activity, loss of social motivation and novelty; enhanced sensorimotor gating and impaired associated memory and coordination. GSK-3α KO mice exhibited a deficit in fear conditioning, however memory formation as assessed by a passive avoidance test was normal, suggesting that the animals are sensitized for active avoidance of a highly aversive stimulus in the fear-conditioning paradigm. Changes in cerebellar structure and function were observed in mutant mice along with a significant decrease of the number and size of Purkinje cells. Conclusion Taken together, these data support a role for the GSK-3α gene in CNS functioning and possible involvement in the development of psychiatric disorders. PMID:19925672

  5. Abnormal structure or function of the amygdala is a common component of neurodevelopmental disorders

    PubMed Central

    Schumann, Cynthia M.; Bauman, Melissa D.; Amaral, David G.

    2010-01-01

    The amygdala, perhaps more than any other brain region, has been implicated in numerous neuropsychiatric and neurodevelopmental disorders. It is part of a system initially evolved to detect dangers in the environment and modulate subsequent responses, which can profoundly influence human behavior. If its threshold is set too low, normally benign aspects of the environment are perceived as dangers, interactions are limited, and anxiety may arise. If set too high, risk taking increases and inappropriate sociality may occur. Given that many neurodevelopmental disorders involve too little or too much anxiety or too little of too much social interaction, it is not surprising that the amygdala has been implicated in many of them. In this chapter, we begin by providing a brief overview of the phylogeny, ontogeny, and function of the amygdala and then appraise data from neurodevelopmental disorders which suggest amygdala dysregulation. We focus on neurodevelopmental disorders where there is evidence of amygdala dysregulation from postmortem studies, structural MRI analyses or functional MRI. However, the results are often disparate and it is not totally clear whether this is due to inherent heterogeneity or differences in methodology. Nonetheless, the amygdala is a common site for neuropathology in neurodevelopmental disorders and is therefore a potential target for therapeutics to alleviate associated symptoms. PMID:20950634

  6. Growth and Age-Related Abnormalities in Cortical Structure and Fracture Risk

    PubMed Central

    2015-01-01

    Vertebral fractures and trabecular bone loss have dominated thinking and research into the pathogenesis and the structural basis of bone fragility during the last 70 years. However, 80% of all fractures are non-vertebral and occur at regions assembled using large amounts of cortical bone; only 20% of fractures are vertebral. Moreover, ~80% of the skeleton is cortical and ~70% of all bone loss is cortical even though trabecular bone is lost more rapidly than cortical bone. Bone is lost because remodelling becomes unbalanced after midlife. Most cortical bone loss occurs by intracortical, not endocortical remodelling. Each remodelling event removes more bone than deposited enlarging existing canals which eventually coalesce eroding and thinning the cortex from 'within.' Thus, there is a need to study the decay of cortical as well as trabecular bone, and to develop drugs that restore the strength of both types of bone. It is now possible to accurately quantify cortical porosity and trabecular decay in vivo. The challenges still to be met are to determine whether measurement of porosity identifies persons at risk for fracture, whether this approach is compliments information obtained using bone densitometry, and whether changes in cortical porosity and other microstructural traits have the sensitivity to serve as surrogates of treatment success or failure. PMID:26394727

  7. Growth and Age-Related Abnormalities in Cortical Structure and Fracture Risk.

    PubMed

    Seeman, Ego

    2015-12-01

    Vertebral fractures and trabecular bone loss have dominated thinking and research into the pathogenesis and the structural basis of bone fragility during the last 70 years. However, 80% of all fractures are non-vertebral and occur at regions assembled using large amounts of cortical bone; only 20% of fractures are vertebral. Moreover, ~80% of the skeleton is cortical and ~70% of all bone loss is cortical even though trabecular bone is lost more rapidly than cortical bone. Bone is lost because remodelling becomes unbalanced after midlife. Most cortical bone loss occurs by intracortical, not endocortical remodelling. Each remodelling event removes more bone than deposited enlarging existing canals which eventually coalesce eroding and thinning the cortex from 'within.' Thus, there is a need to study the decay of cortical as well as trabecular bone, and to develop drugs that restore the strength of both types of bone. It is now possible to accurately quantify cortical porosity and trabecular decay in vivo. The challenges still to be met are to determine whether measurement of porosity identifies persons at risk for fracture, whether this approach is compliments information obtained using bone densitometry, and whether changes in cortical porosity and other microstructural traits have the sensitivity to serve as surrogates of treatment success or failure. PMID:26394727

  8. Structural and magnetic transitions in cubic Mn3Ga.

    PubMed

    Kharel, P; Huh, Y; Al-Aqtash, N; Shah, V R; Sabirianov, R F; Skomski, R; Sellmyer, D J

    2014-03-26

    The structural, magnetic and electron-transport properties of cubic Mn3Ga have been investigated. The alloys prepared by arc melting and melt-spinning show an antiferromagnetic spin order at room temperature but undergo coupled structural and magnetic phase transitions at 600 and 800 K. First-principles calculations show that the observed magnetic properties are consistent with that of a cubic Mn3Ga crystallizing in the disordered Cu3Au-type structure. The samples exhibit metallic electron transport with a resistance minimum near 30 K, followed by a logarithmic upturn below the minimum. The observed anomaly in the low-temperature resistivity has been discussed as a consequence of electron scattering at the low-lying excitations of the structurally disordered Mn3Ga lattice.

  9. Three-Dimensional Magnetic Resonance Imaging of Velopharyngeal Structures

    ERIC Educational Resources Information Center

    Bae, Youkyung; Kuehn, David P.; Sutton, Bradley P.; Conway, Charles A.; Perry, Jamie L.

    2011-01-01

    Purpose: To report the feasibility of using a 3-dimensional (3D) magnetic resonance imaging (MRI) protocol for examining velopharyngeal structures. Using collected 3D MRI data, the authors investigated the effect of sex on the midsagittal velopharyngeal structures and the levator veli palatini (levator) muscle configurations. Method: Ten Caucasian…

  10. Electronic correlation in magnetic contributions to structural energies

    NASA Astrophysics Data System (ADS)

    Haydock, Roger

    For interacting electrons the density of transitions [see http://arxiv.org/abs/1405.2288] replaces the density of states in calculations of structural energies. Extending previous work on paramagnetic metals, this approach is applied to correlation effects on the structural stability of magnetic transition metals. Supported by the H. V. Snyder Gift to the University of Oregon.

  11. Repetitive formation and decay of current sheets in magnetic loops: An origin of diverse magnetic structures

    NASA Astrophysics Data System (ADS)

    Kumar, Dinesh; Bhattacharyya, R.; Smolarkiewicz, P. K.

    2015-01-01

    In this work, evolution of an incompressible, thermally homogeneous, infinitely conducting, viscous magnetofluid is numerically explored as the fluid undergoes repeated events of magnetic reconnection. The initial magnetic field is constructed by a superposition of two linear force-free fields and has similar morphology as the magnetic loops observed in the solar corona. The results are presented for computations with three distinct sets of footpoint geometries. To onset reconnection, we rely on numerical model magnetic diffusivity, in the spirit of implicit large eddy simulation. It is generally expected that in a high Lundquist number fluid, repeated magnetic reconnections are ubiquitous and hence can lead to a host of magnetic structures with considerable observational importance. In particular, the simulations presented here illustrate formations of magnetic islands, rotating magnetic helices and rising flux ropes—depending on the initial footpoint geometry but through the common process of repeated magnetic reconnections. Further, we observe the development of extended current sheets in two case studies, where the footpoint reconnections generate favorable dynamics.

  12. Repetitive formation and decay of current sheets in magnetic loops: An origin of diverse magnetic structures

    SciTech Connect

    Kumar, Dinesh; Bhattacharyya, R.; Smolarkiewicz, P. K.

    2015-01-15

    In this work, evolution of an incompressible, thermally homogeneous, infinitely conducting, viscous magnetofluid is numerically explored as the fluid undergoes repeated events of magnetic reconnection. The initial magnetic field is constructed by a superposition of two linear force-free fields and has similar morphology as the magnetic loops observed in the solar corona. The results are presented for computations with three distinct sets of footpoint geometries. To onset reconnection, we rely on numerical model magnetic diffusivity, in the spirit of implicit large eddy simulation. It is generally expected that in a high Lundquist number fluid, repeated magnetic reconnections are ubiquitous and hence can lead to a host of magnetic structures with considerable observational importance. In particular, the simulations presented here illustrate formations of magnetic islands, rotating magnetic helices and rising flux ropes—depending on the initial footpoint geometry but through the common process of repeated magnetic reconnections. Further, we observe the development of extended current sheets in two case studies, where the footpoint reconnections generate favorable dynamics.

  13. Magnetic assembly of nonmagnetic particles into photonic crystal structures.

    PubMed

    He, Le; Hu, Yongxing; Kim, Hyoki; Ge, Jianping; Kwon, Sunghoon; Yin, Yadong

    2010-11-10

    We report the rapid formation of photonic crystal structures by assembly of uniform nonmagnetic colloidal particles in ferrofluids using external magnetic fields. Magnetic manipulation of nonmagnetic particles with size down to a few hundred nanometers, suitable building blocks for producing photonic crystals with band gaps located in the visible regime, has been difficult due to their weak magnetic dipole moment. Increasing the dipole moment of magnetic holes has been limited by the instability of ferrofluids toward aggregation at high concentration or under strong magnetic field. By taking advantage of the superior stability of highly surface-charged magnetite nanocrystal-based ferrofluids, in this paper we have been able to successfully assemble 185 nm nonmagnetic polymer beads into photonic crystal structures, from 1D chains to 3D assemblies as determined by the interplay of magnetic dipole force and packing force. In a strong magnetic field with large field gradient, 3D photonic crystals with high reflectance (83%) in the visible range can be rapidly produced within several minutes, making this general strategy promising for fast creation of large-area photonic crystals using nonmagnetic particles as building blocks.

  14. Magnetism and structural distortions in uranium sulfide under pressure

    NASA Astrophysics Data System (ADS)

    Jeffries, J. R.; Söderlind, P.; Cynn, H.; Landa, A.; Evans, W. J.; Weir, S. T.; Vohra, Y. K.; Lander, G. H.

    2013-06-01

    Uranium sulfide belongs to a class of uranium monochalcogenides that crystallize in the rocksalt structure and exhibit ferromagnetism at low temperature. The magnetism is believed to play a role in the low-temperature rhombohedral distortion, possibly due to its large magnetic anisotropy. We have performed electrical and structural characterization along with density-functional theory calculations as functions of pressure to help understand the interplay between structure and magnetism in US. Theoretical calculations suggest that ferromagnetic order is responsible for the small distortion at ambient pressure and low temperature. Under pressure, the Curie temperature is reduced monotonically until it discontinuously disappears near a pressure-induced deformation of the crystal structure. This high-pressure distortion is identical to the one correlated with the onset of magnetic order, but with a larger change in the cell angle. Calculations imply a reduction in the electronic band energy as the driving force for the pressure-induced structure, but the loss of magnetic order associated with this distortion remains a mystery. The high-pressure electronic phase diagram may shed light on the magnetostructural free energy landscape of US.

  15. The effect of internal magnetic structure on the fishbone instability

    SciTech Connect

    Roberts, D.W.; Powell, E. ); Kaita, R.; Bell, R.; Chance, M.; Hatcher, R.; Holland, A.; Kaye, S.; Kessel, C.; Kugel, H.; LeBlanc, B.; Manickam, J.; Okabayashi, M.; Paul, S.; Pomphrey, N.; Sauthoff, N.; Sesnic, S.; Takahashi, H.; White, R. . Plasma Physics Lab.); Levinton, F. (Fusion Physics and Technologies, Torrance, CA (Uni

    1992-01-01

    Plasmas exhibiting the fishbone'' instability studied on the PBX-M tokamak show a distinct relationship between the plasma shape, the internal magnetic structure, and the presence or absence of fast ion losses associated with the fishbone mode. We have, for the first time, carried out measurements of the magnetic safety factor profile in fishbone-unstable plasmas, and used the knowledge of the associated experimental equilibria to compare the stability and fast ion loss properties of these plasmas with experimental observations.

  16. The effect of internal magnetic structure on the fishbone instability

    SciTech Connect

    Roberts, D.W.; Powell, E.; Kaita, R.; Bell, R.; Chance, M.; Hatcher, R.; Holland, A.; Kaye, S.; Kessel, C.; Kugel, H.; LeBlanc, B.; Manickam, J.; Okabayashi, M.; Paul, S.; Pomphrey, N.; Sauthoff, N.; Sesnic, S.; Takahashi, H.; White, R.; Levinton, F.; Asakura, N.; Duperrex, P.; Gammel, G.

    1992-01-01

    Plasmas exhibiting the ``fishbone`` instability studied on the PBX-M tokamak show a distinct relationship between the plasma shape, the internal magnetic structure, and the presence or absence of fast ion losses associated with the fishbone mode. We have, for the first time, carried out measurements of the magnetic safety factor profile in fishbone-unstable plasmas, and used the knowledge of the associated experimental equilibria to compare the stability and fast ion loss properties of these plasmas with experimental observations.

  17. Structural inhomogeneity and magnetic properties of strontium hexaferrites

    SciTech Connect

    Pashchenko, V.P.; Samoilenko, Z.A.; Vintonyak, V.M.

    1995-07-01

    The clustered inhomogeneity observed in ferromagnetic materials deepens our concepts of the actual structure of solids and opens new possibilities for controlling their properties. These investigations were made for the purpose of establishment of the relationship between clusterization and magnetic properties of SrO-nFe{sub 2}O{sub 3}, where 5.4 < n < 6.2, metal oxide magnetically hard strontium ferrites.

  18. The interplanetary and solar magnetic field sector structures, 1962 - 1968

    NASA Technical Reports Server (NTRS)

    Jones, D. E.

    1972-01-01

    The interplanetary magnetic field sector structure was observed from late 1962 through 1968. During this time it has been possible to study the manner in which the sector pattern and its relation to the photospheric magnetic field configuration changes from solar minimum to solar maximum. Observations were also made relating sector boundaries to specific regions on the solar disk. These and other observations related to the solar origin of the interplanetary field are briefly reviewed.

  19. Dual-function magnetic structure for toroidal plasma devices

    DOEpatents

    Brown, Robert L.

    1978-01-01

    This invention relates to a support system wherein the iron core and yoke of the plasma current system of a tokamak plasma containment device is redesigned to support the forces of the magnet coils. The containment rings, which occupy very valuable space around the magnet coils, are utilized to serve as yokes for the core such that the conventional yoke is eliminated. The overall result is an improved aspect ratio, reduction in structure, smaller overall size, and improved access to the plasma ring.

  20. Pulmonary Valve Anatomy and Abnormalities: A Pictorial Essay of Radiography, Computed Tomography (CT), and Magnetic Resonance Imaging (MRI).

    PubMed

    Jonas, Samuel N; Kligerman, Seth J; Burke, Allen P; Frazier, Aletta Ann; White, Charles S

    2016-01-01

    Given its inconspicuous appearance on radiography, computed tomography (CT), and magnetic resonance imaging (MRI) the pulmonary valve (PV) is often overlooked as an important cause of both cardiac and pulmonary disease. In this pictorial essay, we review the normal appearance of the PV as well as various congenital anomalies including pulmonary atresia, pulmonary stenosis, and valvular fusion anomalies. Infectious entities, degenerative conditions, and malignant lesions are also depicted. We discuss surgical techniques used to repair both congenital and acquired pulmonary valvular diseases and describe postoperative appearances of the PV on imaging.

  1. Nuclear Magnetic Resonance Shift Reagents: Abnormal 13C Shifts Produced by Complexation of Lanthanide Chelates with Saturated Amines and n-Butyl Isocyanide

    PubMed Central

    Marzin, Claude; Leibfritz, Dieter; Hawkes, Geoffrey E.; Roberts, John D.

    1973-01-01

    Lanthanide-induced shfits of 13C nuclear magnetic resonances are reported for several amines and n-butyl isocyanide. Contact contributions to such shifts, especially of β carbons, are clearly important for the chelates of Eu+3 and Pr+3. The importance of contact terms is shown to change in a rather predictable manner with the structure of the amine. PMID:16592062

  2. Generation of magnetic structures on the solar photosphere

    SciTech Connect

    Gangadhara, R. T.; Krishan, V.; Bhowmick, A. K.; Chitre, S. M.

    2014-06-20

    The lower solar atmosphere is a partially ionized plasma consisting of electrons, ions, and neutral atoms. In this, which is essentially a three-fluid system, the Hall effect arises from the treatment of the electrons and ions as two separate fluids and the ambipolar diffusion arises from the inclusion of neutrals as the third fluid. The Hall effect and ambipolar diffusion have been shown to be operational in a region beginning from near the photosphere up to the chromosphere. In a partially ionized plasma, the magnetic induction is subjected to ambipolar diffusion and the Hall drift in addition to the usual resistive dissipation. These nonlinear effects create sharp magnetic structures which then submit themselves to various relaxation mechanisms. A first-principles derivation of these effects in a three-fluid system and an analytic solution to the magnetic induction equation in a stationary state are presented, which in the general case includes the Hall effect, ambipolar diffusion, and ohmic dissipation. The temporal evolution of the magnetic field is then investigated under the combined as well as the individual effects of the Hall drift and ambipolar diffusion to demonstrate the formation of steep magnetic structures and the resultant current sheet formation. These structures have just the right features for the release of magnetic energy into the solar atmosphere.

  3. Abnormal coexistence of unipolar, bipolar, and threshold resistive switching in an Al/NiO/ITO structure.

    PubMed

    Yuan, Xin-Cai; Tang, Jin-Long; Zeng, Hui-Zhong; Wei, Xian-Hua

    2014-01-01

    This paper reports an abnormal coexistence of different resistive switching behaviors including unipolar (URS), bipolar (BRS), and threshold switching (TRS) in an Al/NiO/indium tin oxide (ITO) structure fabricated by chemical solution deposition. The switching behaviors have been strongly dependent on compliance current (CC) and switching processes. It shows reproducible URS and BRS after electroforming with low and high CC of 1 and 3 mA, respectively, which is contrary to previous reports. Furthermore, in the case of high-forming CC, TRS is observed after several switching cycles with a low-switching CC. Analysis of current-voltage relationship demonstrates that Poole-Frenkel conduction controlled by localized traps should be responsible for the resistance switching. The unique behaviors can be dominated by Joule heating filament mechanism in the dual-oxygen reservoir structure composed of Al/NiO interfacial layer and ITO. The tunable switching properties can render it flexible for device applications. PMID:24940181

  4. Microstructural, Magnetic Anisotropy, and Magnetic Domain Structure Correlations in Epitaxial FePd Thin Films with Perpendicular Magnetic Anisotropy

    NASA Technical Reports Server (NTRS)

    Skuza, J. R.; Clavero, C.; Yang, K.; Wincheski, B.; Lukaszew, R. A.

    2009-01-01

    L1(sub 0)-ordered FePd epitaxial thin films were prepared using dc magnetron sputter deposition on MgO (001) substrates. The films were grown with varying thickness and degree of chemical order to investigate the interplay between the microstructure, magnetic anisotropy, and magnetic domain structure. The experimentally measured domain size/period and magnetic anisotropy in this high perpendicular anisotropy system were found to be correlated following the analytical energy model proposed by Kooy and Enz that considers a delicate balance between the domain wall energy and the demagnetizing stray field energy.

  5. Validation and Benchmarking of a Practical Free Magnetic Energy and Relative Magnetic Helicity Budget Calculation in Solar Magnetic Structures

    NASA Astrophysics Data System (ADS)

    Moraitis, K.; Tziotziou, K.; Georgoulis, M. K.; Archontis, V.

    2014-12-01

    In earlier works we introduced and tested a nonlinear force-free (NLFF) method designed to self-consistently calculate the coronal free magnetic energy and the relative magnetic helicity budgets of observed solar magnetic structures. In principle, the method requires only a single, photospheric or low-chromospheric, vector magnetogram of a quiet-Sun patch or an active region and performs calculations without three-dimensional magnetic and velocity-field information. In this work we strictly validate this method using three-dimensional coronal magnetic fields. Benchmarking employs both synthetic, three-dimensional magnetohydrodynamic simulations and nonlinear force-free field extrapolations of the active-region solar corona. Our time-efficient NLFF method provides budgets that differ from those of more demanding semi-analytical methods by a factor of approximately three, at most. This difference is expected to come from the physical concept and the construction of the method. Temporal correlations show more discrepancies that are, however, soundly improved for more complex, massive active regions, reaching correlation coefficients on the order of, or exceeding, 0.9. In conclusion, we argue that our NLFF method can be reliably used for a routine and fast calculation of the free magnetic energy and relative magnetic helicity budgets in targeted parts of the solar magnetized corona. As explained in this article and in previous works, this is an asset that can lead to valuable insight into the physics and triggering of solar eruptions.

  6. Aeromagnetic map of Korea; Magnetic patterns and structural features

    NASA Astrophysics Data System (ADS)

    Park, Yeong-Sue; Rim, Hyoungrea; Lim, Mutaek; Shin, Young Hong

    2014-05-01

    Regional airborne magnetic survey is very cost-effective mapping tool. Magnetic anomaly maps have abundant information, which are an important tool for understanding the geological evolution and mineral exploration. The pattern of magnetic anomaly map is a powerful indicator of geologic structure and rock formation. Magnetic anomaly patterns primarily reflect the distribution and structural setting of magnetized material within the crust. These features including amplitude and orientation of individual anomalies or the texture of anomalous regions can provide useful constraints for geological interpretation. KIGAM has conducted airborne magnetic mapping programme since 1982, and has coverage of almost whole the country. The latest version of airborne magnetic anomaly map was published by compiling data acquired from 1982 to 2012. The helicopter-borne surveys were flown by a line spacing 1~2 km with control lines of 5~8 km. The flight altitude was tried to keep 100~150 m above ground surface with sampling distance of 30m. The data were continued to the reference level of 300 m above ground level, and regional field was reduced by 11th generation IGRF. This paper introduced the latest version of magnetic anomaly map of Korea, and briefly examined the magnetic characteristics, with geologic characteristics and structural features of tectonic zones. Furthermore, magnetic patterns were quantitatively analyzed by using skeletonization technique. Korea, southern part of the Korean peninsula, could be divided in 5 tectonic provinces, such as, Gyeonggi massif, Okcheon fold belt, Sobaeksan massif, Gyeongsang basin, and circum-Pacific alkali volcanic zone. Magnetic anomalies in Gyeonggi massif zone are broadly distributed with moderately high amplitude, and the dominant trend is NE, but not strong. Okcheon fold belt can be magnetically characterized as strong dominant NE trend (Sinian direction) and linear positive anomalies of high amplitude. Sobaeksan massif is magnetically

  7. Magnetic and crystallographic structures in UTX intermetallic compounds

    SciTech Connect

    Robinson, R.A.; Lawson, A.C.; Sechovsky, V.; Havela, L.; Kergadallan, Y.; Nakotte, H.; de Boer, F.R.

    1993-08-01

    Uranium, along with other actinides and lanthanides, forms a large group of ternary intermetallic compounds of stoichiometry UTX (T = transition metal, X = p-electron metal). These compounds are formed in several structure types and the occurrence and stability of particular structures with respect to the transition metal content suggests reasonable systematics. The authors have also investigated the magnetic structures of selected UTX compounds and it is revealing to relate the crystallographic and magnetic structures, because of the relationship between the magnetic symmetry and that of the U-atom environment produced by the 5f-ligand hybridization, and the consequent anisotropic exchange. Those of ZrNiAl structure type are collinear, with moments along the hexagonal c-axis. In the orthorhombic NiSiTi structure type, the moments are confined to the b- c plane (perpendicular to the uranium chains) and the structures are often incommensurate. In the hexagonal CaIn{sub 2} (or GaGeLi) structure type, the magnetic structures form in an orthorhombic cell, and at least in the disordered centric group, again the moments lie perpendicular to the nearest-neighbor uranium spacing. This work presents a phenomenology of trends in UTX ternary compounds. It is shown that there is an apparent strong hybridization parallel to nearest neighbor U-U directions, with ferromagnetic coupling in the same directions. There may be a systematic relationship between the hybridization anisotropy and the magnetic anisotropy, in which the quantization axes are the same and the moments point along directions of relatively weak hybridization.

  8. Active Region Magnetic Structure Observed in the Photosphere and Chromosphere

    NASA Technical Reports Server (NTRS)

    Leka, K. D.; Metcalf, Thomas R.

    2001-01-01

    The magnetic flux above sunspots and plage in NOAA (National Oceanic and Atmospheric Administration) Active Region 8299 has been measured in the photosphere and the chromosphere. We investigate the vertical magnetic structure above the umbrae, penumbrae and plage regions using quantitative statistical comparisons of the photospheric and chromospheric vector magnetic flux data. The results include: (1) a decrease in flux with height, (2) the direct detection of the superpenumbral canopy in the chromosphere, (3) values for dB/dz which are consistent with earlier investigations when derived from a straight difference between the two datasets but quite low when derived from the delta x B = 0 condition, (4) a monolithic structure in the umbra which extends well into the upper chromosphere with a very complex and varied structure in the penumbra and plage, as evidenced by (5) a uniform magnetic scale height in the umbrae with an abrupt jump to widely varying scale heights in the penumbral and plage regions. Further, we find (6) evidence for a very large (delta z approximately equals 3Mm) height difference between the atmospheric layers sampled in the two magnetograms, almost a factor of three larger than that implied by atmospheric models. We additionally test the apropriateness of using photospheric magnetic flux as a boundary for field-line extrapolations, and find a better agreement with observed coronal structure when the chromospheric flux is used as a boundary.

  9. Structural analysis of placental terminal villi from growth-restricted pregnancies with abnormal umbilical artery Doppler waveforms.

    PubMed

    Macara, L; Kingdom, J C; Kaufmann, P; Kohnen, G; Hair, J; More, I A; Lyall, F; Greer, I A

    1996-01-01

    The abnormal umbilical artery Doppler waveform represented by absent end-diastolic flow velocity (AEDFV) identifies a group of preterm small-for-gestational age fetuses that are at high risk of perinatal death due to chronic fetal hypoxia. The placental ischaemia that results from inadequate trophoblast invasion of spiral arterioles leads to an assumption of placental villous hypoxia, though an alternative explanation is that the placenta fails to adequately transfer oxygen to the fetus from the intervillous space. Because oxygen transport takes place within the terminal villi, we undertook the first detailed studies of villous ultrastructure structure and immunohistochemistry in order to determine the likely origin of fetal hypoxia in this condition. Terminal villi were examined ultrastructurally using transmission electron microscopy and by immunohistochemical localization of matrix molecules (laminin and collagens I, III and IV) and a marker of cell proliferation (MIB-1), in 16 small-for-gestational age pregnancies with AEDFV in the umbilical artery [deemed to have intrauterine growth restriction (IUGR)] and in 16 gestation age-matched controls. Terminal villi from the IUGR cases were smaller in diameter (P < 0.02) and had several abnormal features in comparison with the controls; increased syncytial nuclei (P < 0.01), reduced cytotrophoblast nuclei (P < 0.01), thickened basal lamina (P < 0.01), and increased stromal deposition of collagens and laminin. The amount of proliferating cytotrophoblast was reduced in the IUGR group (P < 0.014) and the degree of capillary erythrocyte congestion within terminal villous capillaries was increased (P < 0.001). Several of the structural differences in the terminal villi of the IUGR group such as reduced cytotrophoblast proliferation and stromal fibrosis are incompatible with the prevailing view of placental hypoxia in IUGR. Rather thickening of the basal lamina and congestion of the capillaries by erythrocytes are predicted

  10. Spectropolarimetry of fine magnetized structures in the upper solar atmosphere

    NASA Astrophysics Data System (ADS)

    Schad, Thomas Anthony

    2013-12-01

    One of the earliest indications of magnetic fields acting in the solar atmosphere came at the beginning of the 20th century when George Hale noted a "decided definiteness of structure" in photographs within the Hydrogen Balmer-alpha line core. Fine structure both in the chromosphere and in the corona result from processes that are not well understood but accepted as a consequence of the solar magnetic field. Our knowledge of this field is lacking, and until recently, the assumed relationship between fine thermal structure and the magnetic field remained untested. Here, spectropolarimetric diagnostics of fine structures in the solar chromosphere and cool corona are advanced using the infrared He I triplet at 1083 nm. Precise calibration procedures are developed for the Facility Infrared Spectropolarimeter (FIRS), recently commissioned at the Dunn Solar Telescope. Together with high-order adaptive optics, we simultaneously map fine structures while obtaining a polarimetric sensitivity of up to 2 x 10--4 of the incoming intensity. These instrument improvements result in the first maps of the He I polarized signatures within an active region superpenumbra, where Hale first recognized fine-structuring. Selective absorption and emission processes due to non-equilibrium optical pumping are recognized. Our interpretation, using advanced inversions of the He I triplet, provides confirmation of Hale's initial suspicion---the fine structures of the solar chromosphere are visual markers for the magnetic field. Yet, the fine chromospheric thermal structure is not matched by an equivalently fine magnetic structure. Our ability to measure this field suggests the utility of the He I triplet as an inner boundary condition for the inner heliospheric magnetic field. In the corona itself, we infer the vector properties of a catastrophically-cooled coronal loop, uniting space-based and ground-based instrumentation. We determine how fine loops are anchored in the photosphere via a

  11. Understanding spin structure in metallacrown single-molecule magnets using magnetic compton scattering.

    PubMed

    Deb, Aniruddha; Boron, Thaddeus T; Itou, Masayoshi; Sakurai, Yoshiharu; Mallah, Talal; Pecoraro, Vincent L; Penner-Hahn, James E

    2014-04-01

    The 3d-4f mixed metallacrowns frequently show single-molecule magnetic behavior. We have used magnetic Compton scattering to characterize the spin structure and orbital interactions in three isostructural metallacrowns: Gd2Mn4, Dy2Mn4, and Y2Mn4. These data allow the direct determination of the spin only contribution to the overall magnetic moment. We find that the lanthanide 4f spin in Gd2Mn4 and Dy2Mn4 is aligned parallel to the Mn 3d spin. For Y2Mn4 (manganese-only spin) we find evidence for spin delocalization into the O 2p orbitals. Comparing the magnetic Compton scattering data with SQUID studies that measure the total magnetic moment suggests that Gd2Mn4 and Y2Mn4 have only a small orbital contribution to the moment. In contrast, the total magnetic moment for Dy2Mn4 MCs is much larger than the spin-only moment, demonstrating a significant orbital contribution to the overall magnetic moment. Overall, these data provide direct insight into the correlation of molecular design with molecular magnetic properties.

  12. Electron vortex magnetic holes: A nonlinear coherent plasma structure

    SciTech Connect

    Haynes, Christopher T. Burgess, David; Sundberg, Torbjorn; Camporeale, Enrico

    2015-01-15

    We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.

  13. Electron vortex magnetic holes: A nonlinear coherent plasma structure

    NASA Astrophysics Data System (ADS)

    Haynes, Christopher T.; Burgess, David; Camporeale, Enrico; Sundberg, Torbjorn

    2015-01-01

    We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.

  14. Inherited structural cytogenetic abnormalities detected incidentally in fetuses diagnosed prenatally: frequency, parental-age associations, sex-ratio trends, and comparisons with rates of mutants.

    PubMed Central

    Hook, E B; Schreinemachers, D M; Willey, A M; Cross, P K

    1984-01-01

    Rates of structural chromosome abnormalities were analyzed in 24,951 fetuses studied prenatally in which there were no grounds to suspect an inherited abnormality. In about one in 200 prenatal cytogenetic diagnoses, an unexpected structural abnormality was found. The observed rate was 5.3 per 1,000, of which 1.7 per 1,000 were unbalanced and 3.6 per 1,000 balanced. The rate of inherited abnormalities was 3.1-3.7 per 1,000 (0.4-0.9 per 1,000 for unbalanced abnormalities and 2.6-2.8 per 1,000 for balanced abnormalities). The rate of mutants in this series was, by contrast, 1.6-2.2 per 1,000 (0.8-1.2 per 1,000 for unbalanced abnormalities and 0.8-1.0 per 1,000 for balanced abnormalities). The rate of balanced Robertsonian translocation carriers was 0.6 per 1,000 (about 0.25 per 1,000 for mutants and 0.35 per 1,000 for inherited abnormalities), and for other balanced abnormalities, 3.0 per 1,000 (about 0.6 per 1,000 for mutants and 2.4 per 1,000 for inherited abnormalities). The rates of unbalanced Robertsonian translocations was about 0.1 per 1,000, almost all of which were mutants. For supernumerary rearrangements, the rate was 0.9 per 1,000 (about 0.4 per 1,000 inherited and 0.5 per 1,000 mutant). The rates of all unbalanced (nonmosaic) inherited abnormalities (4.0-5.2 per 10,000) were intermediate between higher rates estimated in all conceptuses (9.1-15.8 per 10,000) and rates observed in newborns (1.5-2.5 per 10,000). This trend is probably attributable to fetal mortality associated with unbalanced rearrangements. The rates of balanced (nonmosaic) inherited abnormalities (26.0-28.0 per 10,000), however, were considerably higher than the rates in all conceptuses (13-16.7 per 10,000) or in all live births (12.2-16.0 per 10,000). The major difference was in the rate of inversions. The use of "banding" methods in the studies of amniocentesis but not in most of the live births or abortus studies probably contributes to at least some of these differences. One trend in

  15. Structure organization and magnetic properties of microscale ferrogels: The effect of particle magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Ryzhkov, Aleksandr V.; Melenev, Petr V.; Balasoiu, Maria; Raikher, Yuriy L.

    2016-08-01

    The equilibrium structure and magnetic properties of a ferrogel object of small size (microferrogel(MFG)) are investigated by coarse-grained molecular dynamics. As a generic model of a microferrogel (MFG), a sample with a lattice-like mesh is taken. The solid phase of the MFG consists of magnetic (e.g., ferrite) nanoparticles which are mechanically linked to the mesh making some part of its nodes. Unlike previous models, the finite uniaxial magnetic anisotropy of the particles, as it is the case for real ferrogels, is taken into account. For comparison, two types of MFGs are considered: MFG-1, which dwells in virtually non-aggregated state independently of the presence of an external magnetic field, and MFG-2, which displays aggregation yet under zero field. The structure states of the samples are analyzed with the aid of angle-resolved radial distribution functions and cluster counts. The results reveal the crucial role of the matrix elasticity on the structure organization as well as on magnetization of both MFGs. The particle anisotropy, which plays insignificant role in MFG-1 (moderate interparticle magnetodipole interaction), becomes an important factor in MFG-2 (strong interaction). There, the restrictions imposed on the particle angular freedom by the elastic matrix result in notable diminution of the particle chain lengths as well as the magnetization of the sample. The approach proposed enables one to investigate a large variety of MFGs, including those of capsule type and to purposefully choose the combination of their magnetoelastic parameters.

  16. Structure organization and magnetic properties of microscale ferrogels: The effect of particle magnetic anisotropy.

    PubMed

    Ryzhkov, Aleksandr V; Melenev, Petr V; Balasoiu, Maria; Raikher, Yuriy L

    2016-08-21

    The equilibrium structure and magnetic properties of a ferrogel object of small size (microferrogel(MFG)) are investigated by coarse-grained molecular dynamics. As a generic model of a microferrogel (MFG), a sample with a lattice-like mesh is taken. The solid phase of the MFG consists of magnetic (e.g., ferrite) nanoparticles which are mechanically linked to the mesh making some part of its nodes. Unlike previous models, the finite uniaxial magnetic anisotropy of the particles, as it is the case for real ferrogels, is taken into account. For comparison, two types of MFGs are considered: MFG-1, which dwells in virtually non-aggregated state independently of the presence of an external magnetic field, and MFG-2, which displays aggregation yet under zero field. The structure states of the samples are analyzed with the aid of angle-resolved radial distribution functions and cluster counts. The results reveal the crucial role of the matrix elasticity on the structure organization as well as on magnetization of both MFGs. The particle anisotropy, which plays insignificant role in MFG-1 (moderate interparticle magnetodipole interaction), becomes an important factor in MFG-2 (strong interaction). There, the restrictions imposed on the particle angular freedom by the elastic matrix result in notable diminution of the particle chain lengths as well as the magnetization of the sample. The approach proposed enables one to investigate a large variety of MFGs, including those of capsule type and to purposefully choose the combination of their magnetoelastic parameters. PMID:27544124

  17. Role of Cardiac Magnetic Resonance Imaging in the Management and Treatment of Ventricular Tachycardia in Patients With Structural Heart Disease.

    PubMed

    Mehrotra, Amit K; Callans, David

    2015-01-01

    Treatment for ventricular tachycardia (VT) generally includes 1 or more of the following options: antiarrhythmic therapy, an implantable cardioverter-defibrillator and/or catheter ablation. Catheter ablation is performed with an electroanatomic mapping system to define the heart's 3D anatomy, as well as regions of scar. Radiofrequency energy is then applied to areas of abnormal substrate within which are located channels critical to the VT circuit. Cardiac magnetic resonance (CMR) imaging is a non-invasive modality that provides high-resolution images of cardiac structure and function. CMR has become a very useful tool for sudden cardiac death risk stratification and to facilitate successful radiofrequency ablation of VT in patients with abnormal cardiac substrate. The role of CMR in the management and treatment of VT in patients with structural heart disease is reviewed.

  18. Recurring structural chromosome abnormalities in peripheral blood lymphocytes of patients with mycosis fungoides/Sézary syndrome.

    PubMed

    Thangavelu, M; Finn, W G; Yelavarthi, K K; Roenigk, H H; Samuelson, E; Peterson, L; Kuzel, T M; Rosen, S T

    1997-05-01

    Cytogenetic analysis was performed on peripheral blood lymphocyte cultures from 19 patients with mycosis fungoides (MF)/Sézary syndrome (SS) stimulated with either phytohemagglutinin, a conventional mitogen, or a combination of interleukin-2 (IL-2) plus IL-7. The use of both PHA-stimulated and IL-2 plus IL-7-stimulated cultures enhanced the ability to identify clonal abnormalities. Clonal abnormalities were observed in 11 patients (53%) including one with monosomy for the sex chromosome as the sole abnormality. Five of the 11 patients with clonal abnormalities had normal peripheral white blood cell counts, indicating detectability of clones in the absence of frankly leukemic disease. The presence of clonal abnormalities correlated with advanced stage disease and a significantly reduced survival duration from the time of cytogenetic studies. Clonal abnormalities involving chromosomes 1 and 8 were observed in six cases. In five cases with aberrations of chromosome 1, loss of material involved the region between 1p22 and 1p36. In an additional case, a reciprocal translocation involving 1p33 was observed. Clonal abnormalities involving chromosomes 10 and 17 were observed in 5 cases, clonal abnormalities involving chromosome 2 in 4 cases, and clonal abnormalities involving chromosomes 4, 5, 6, 9, 13, 15, 19, and 20 in 3 cases. In 2 cases a der(8)t(8;17)(p11;q11) was observed. Regions of the genome that encode T-cell receptors were not involved in abnormalities. The region between 1p22 and 1p36 is identified as a region of the genome that requires detailed analysis toward the identification of potential gene(s) involved in the process of malignant transformation and/or progression in MF/SS.

  19. Electronic structure and magnetism of ThFeAsN

    NASA Astrophysics Data System (ADS)

    Wang, Guangtao; Shi, Xianbiao

    2016-03-01

    The electronic structure and magnetic properties of ThFeAsN, a newly discovered superconductor, are investigated by means of first-principles calculations. ThFeAsN shares electronic structure and magnetic properties similar to those of LaOFeAs. Its calculated ground state is the stripe antiferromagnetic state. The hole-like Fermi surfaces (FSs) along the Γ\\text-Z line largely overlap with the electron-like FS along the M\\text-A line with the vector q= (π, π, 0) . Such significant FS nesting induces a peak of the bare susceptibility χ0(q ) at the M-point.

  20. Structure of a Magnetic Flux Annihilation Layer Formed by the Collision of Supersonic, Magnetized Plasma Flows.

    PubMed

    Suttle, L G; Hare, J D; Lebedev, S V; Swadling, G F; Burdiak, G C; Ciardi, A; Chittenden, J P; Loureiro, N F; Niasse, N; Suzuki-Vidal, F; Wu, J; Yang, Q; Clayson, T; Frank, A; Robinson, T S; Smith, R A; Stuart, N

    2016-06-01

    We present experiments characterizing the detailed structure of a current layer, generated by the collision of two counterstreaming, supersonic and magnetized aluminum plasma flows. The antiparallel magnetic fields advected by the flows are found to be mutually annihilated inside the layer, giving rise to a bifurcated current structure-two narrow current sheets running along the outside surfaces of the layer. Measurements with Thomson scattering show a fast outflow of plasma along the layer and a high ion temperature (T_{i}∼Z[over ¯]T_{e}, with average ionization Z[over ¯]=7). Analysis of the spatially resolved plasma parameters indicates that the advection and subsequent annihilation of the inflowing magnetic flux determines the structure of the layer, while the ion heating could be due to the development of kinetic, current-driven instabilities. PMID:27314720

  1. High temperature structural and magnetic properties of cobalt nanorods

    SciTech Connect

    Ait Atmane, Kahina; Zighem, Fatih; Soumare, Yaghoub; Ibrahim, Mona; Boubekri, Rym; Maurer, Thomas; Margueritat, Jeremie; Piquemal, Jean-Yves; Ott, Frederic; Chaboussant, Gregory; Schoenstein, Frederic; Jouini, Noureddine; Viau, Guillaume

    2013-01-15

    We present in this paper the structural and magnetic properties of high aspect ratio Co nanoparticles ({approx}10) at high temperatures (up to 623 K) using in-situ X ray diffraction (XRD) and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. The coercivity can be modelled by {mu}{sub 0}H{sub C}=2(K{sub MC}+K{sub shape})/M{sub S} with K{sub MC} the magnetocrystalline anisotropy constant, K{sub shape} the shape anisotropy constant and M{sub S} the saturation magnetization. H{sub C} decreases linearly when the temperature is increased due to the loss of the Co magnetocrystalline anisotropy contribution. At 500 K, 50% of the room temperature coercivity is preserved corresponding to the shape anisotropy contribution only. We show that the coercivity drop is reversible in the range 300-500 K in good agreement with the absence of particle alteration. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation. - Graphical abstract: We present in this paper the structural and magnetic properties of high aspect ratio Co nanorods ({approx}10) at high temperatures (up to 623 K) using in-situ X-ray diffraction and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation. Highlights: Black-Right-Pointing-Pointer Ferromagnetic Co nanorods are prepared using the polyol process. Black-Right-Pointing-Pointer The structural and texture properties of the Co nanorods are preserved up to 500 K. Black-Right-Pointing-Pointer The magnetic properties of the Co nanorods are irreversibly altered above 525 K.

  2. Magnetic and Crystal Structure of α-RuCl3

    NASA Astrophysics Data System (ADS)

    Sears, Jennifer

    The layered honeycomb material α-RuCl3 has been proposed as a candidate material to show significant bond-dependent Kitaev type interactions. This has prompted several recent studies of magnetism in this material that have found evidence for multiple magnetic transitions in the temperature range of 8-14 K. We will present elastic neutron scattering measurements collected using a co-aligned array of α-RuCl3 crystals, identifying zigzag magnetic order within the honeycomb planes with an ordering temperature of ~8 K. It has been reported that the ordering temperature depends on the c axis periodicity of the layered structure, with ordering temperatures of 8 and 14 K for three and two-layer periodicity respectively. While the in-plane magnetic order has been identified, it is clear that a complete understanding of magnetic ordering and interactions will depend on the three dimensional structure of the crystal. Evidence of a structural transition at ~150 K has been reported and questions remain about the structural details, in particular the stacking of the honeycomb layers. We will present x-ray diffraction measurements investigating the low and high temperature structures and stacking disorder in α-RuCl3. Finally, we will present inelastic neutron scattering measurements of magnetic excitations in this material. Work done in collaboration with K. W. Plumb (Johns Hopkins University), J. P. Clancy, Young-June Kim (University of Toronto), J. Britten (McMaster University), Yu-Sheng Chen (Argonne National Laboratory), Y. Qiu, Y. Zhao, D. Parshall, and J. W. Lynn (NCNR).

  3. Stability of magnetic nano-structures against erroneous shape modifications

    NASA Astrophysics Data System (ADS)

    Blachowicz, T.; Ehrmann, A.

    2016-04-01

    Magnetic nano-structures can be used in various applications. Due to their possible utilization in data storage media, examinations of nano-structured systems often aim at decreasing the pattern size, in order to enhance the possible information density in a given area. Since this scaling process is limited by the resolution of the lithography process which is used to produce the nano-particles, it is important to determine the influence of erroneous shape modifications on the magnetic properties, such as magnetization reversal processes and coercive fields. For this, a square nano-wire system from permalloy has been simulated using Magpar. In a former work, changes of the wire diameter have been shown to result in different magnetization reversal mechanisms and significantly altered coercive fields. In a new project, the intersections of the wires - which are most susceptible to undesired shape modifications - have been changed by adding or subtracting parts. Additionally, the wire intersections have been separated step by step, resulting in a qualitatively changed angular dependence of the coercive fields. Similar experiments have been performed for nano-squares with walls of rectangular cross-section. This study allows for estimation of the reliability of magnetic properties of nano-structures with respect to undesired shape modifications in the lithography process.

  4. Functional magnetic resonance imaging reveals abnormal brain connectivity in EGR3 gene transfected rat model of schizophrenia.

    PubMed

    Song, Tianbin; Nie, Binbin; Ma, Ensen; Che, Jing; Sun, Shilong; Wang, Yuli; Shan, Baoci; Liu, Yawu; Luo, Senlin; Ma, Guolin; Li, Kefeng

    2015-05-01

    Schizophrenia is characterized by the disorder of "social brain". However, the alternation of connectivity density in brain areas of schizophrenia patients remains largely unknown. In this study, we successfully created a rat model of schizophrenia by the transfection of EGR3 gene into rat brain. We then investigated the connectivity density of schizophrenia susceptible regions in rat brain using functional magnetic resonance imaging (fMRI) in combination with multivariate Granger causality (GC) model. We found that the average signal strength in prefrontal lobe and hippocampus of schizophrenia model group was significantly higher than the control group. Bidirectional Granger causality connection was observed between hippocampus and thalamic in schizophrenia model group. Both connectivity density and Granger causality connection were changed in prefrontal lobe, hippocampus and thalamus after risperidone treatment. Our results indicated that fMRI in combination with GC connection analysis may be used as an important method in diagnosis of schizophrenia and evaluation the effect of antipsychotic treatment. These findings support the connectivity disorder hypothesis of schizophrenia and increase our understanding of the neural mechanisms of schizophrenia.

  5. Magnetic Field in Atypical Prominence Structures: Bubble, Tornado, and Eruption

    NASA Astrophysics Data System (ADS)

    Levens, P. J.; Schmieder, B.; López Ariste, A.; Labrosse, N.; Dalmasse, K.; Gelly, B.

    2016-08-01

    Spectropolarimetric observations of prominences have been obtained with the THEMIS telescope during four years of coordinated campaigns. Our aim is now to understand the conditions of the cool plasma and magnetism in “atypical” prominences, namely when the measured inclination of the magnetic field departs, to some extent, from the predominantly horizontal field found in “typical” prominences. What is the role of the magnetic field in these prominence types? Are plasma dynamics more important in these cases than the magnetic support? We focus our study on three types of “atypical” prominences (tornadoes, bubbles, and jet-like prominence eruptions) that have all been observed by THEMIS in the He i D3 line, from which the Stokes parameters can be derived. The magnetic field strength, inclination, and azimuth in each pixel are obtained by using the inversion method of principal component analysis on a model of single scattering in the presence of the Hanle effect. The magnetic field in tornadoes is found to be more or less horizontal, whereas for the eruptive prominence it is mostly vertical. We estimate a tendency toward higher values of magnetic field strength inside the bubbles than outside in the surrounding prominence. In all of the models in our database, only one magnetic field orientation is considered for each pixel. While sufficient for most of the main prominence body, this assumption appears to be oversimplified in atypical prominence structures. We should consider these observations as the result of superposition of multiple magnetic fields, possibly even with a turbulent field component.

  6. Detection of Left Ventricular Regional Dysfunction and Myocardial Abnormalities Using Complementary Cardiac Magnetic Resonance Imaging in Patients with Systemic Sclerosis without Cardiac Symptoms: A Pilot Study.

    PubMed

    Kobayashi, Yasuyuki; Kobayashi, Hitomi; T Giles, Jon; Yokoe, Isamu; Hirano, Masaharu; Nakajima, Yasuo; Takei, Masami

    2016-01-01

    Objective We sought to detect the presence of left ventricular regional dysfunction and myocardial abnormalities in systemic sclerosis (SSc) patients without cardiac symptoms using a complementary cardiac magnetic resonance (CMR) imaging approach. Methods Consecutive patients with SSc without cardiac symptoms and healthy controls underwent CMR on a 1.5 T scanner. The peak systolic regional function in the circumferential and radial strain (Ecc, % and Err, %) were calculated using a feature tracking analysis on the mid-left ventricular slices obtained with cine MRI. In addition, we investigated the myocardial characteristics by contrast MRI. Pharmacological stress and rest perfusion scans were performed to assess perfusion defect (PD) due to micro- or macrovascular impairment, and late gadolinium enhancement (LGE) images were obtained for the assessment of myocarditis and/or fibrosis. Results We compared 15 SSc patients with 10 healthy controls. No statistically significant differences were observed in the baseline characteristics between the patients and healthy controls. The mean peak Err and Ecc of all segments was significantly lower in the patients than the controls (p=0.011 and p=0.003, respectively). Four patients with LGE (28.6%) and seven patients with PD (50.0%) were observed. PD was significantly associated with digital ulcers (p=0.005). Utilizing a linear regression model, the presence of myocardial LGE was significantly associated with the peak Ecc (p=0.024). After adjusting for age, the association between myocardial LGE and the peak Ecc was strengthened. Conclusion A subclinical myocardial involvement, as detected by CMR, was prevalent in the SSc patients without cardiac symptoms. Regional dysfunction might predict the myocardial abnormalities observed in SSc patients without cardiac symptoms.

  7. Assessing the Structure of Isotropic and Anisotropic Turbulent Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Fatuzzo, Marco; Holden, Lisa; Grayson, Lindsay; Wallace, Kirk

    2016-10-01

    Turbulent magnetic fields permeate our universe, impacting a wide range of astronomical phenomena across all cosmic scales. A clear example is the magnetic field that threads the interstellar medium (ISM), which impacts the motion of cosmic rays through that medium. Understanding the structure of magnetic turbulence within the ISM and how it relates to the physical quantities that characterize it can thus inform our analysis of particle transport within these regions. Toward that end, we probe the structure of magentic turbulence through the use of Lyapunov exponents for a suite of isotropic and nonisotropic Alfvénic turbulence profiles. Our results provide a means of calculating a “turbulence lengthscale” that can then be connected to how cosmic rays propagate through magentically turbulent environments, and we perform such an analysis for molecular cloud environments.

  8. Structure of magnetic resonance in 87Rb atoms

    NASA Astrophysics Data System (ADS)

    Kozlov, A. N.; Zibrov, S. A.; Zibrov, A. A.; Yudin, V. I.; Taichenachev, A. V.; Yakovlev, V. P.; Tsygankov, E. A.; Zibrov, A. S.; Vassiliev, V. V.; Velichansky, V. L.

    2016-05-01

    Magnetic resonance at the F g = 1 rightleftarrows F e = 1 transition of the D 1 line in 87Rb has been studied with pumping and detection by linearly polarized radiation and detection at the double frequency of the radiofrequency field. The intervals of allowed values of the static and alternating magnetic fields in which magnetic resonance has a single maximum have been found. The structure appearing beyond these intervals has been explained. It has been shown that the quadratic Zeeman shift is responsible for the three-peak structure of resonance; the radiofrequency shift results in the appearance of additional extrema in resonance, which can be used to determine the relaxation constant Γ2. The possibility of application in magnetometry has been discussed.

  9. Controllability of brushite structural parameters using an applied magnetic field.

    PubMed

    Kuznetsov, V N; Yanovska, A A; Stanislavov, A S; Danilchenko, S N; Kalinkevich, A N; Sukhodub, L F

    2016-03-01

    The paper studies the influence of low intensity static magnetic field on brushite structural and microstructural parameters using the X-ray diffraction and the transmission electron microscopy. This effect was shown to have various influences on DCPD (Dicalcium Phosphate Dihydrate) structure depending on a magnetic field configuration or time of synthesis, which allows achieving controllability of the main properties of an obtained material. The influence of the magnetic field leads mostly to the decrease of crystallite sizes with no impact on the crystal lattice parameters. In (0 2 0) and (1 5 0) planes the growth of crystallite sizes is observed after 2 and 3 days of crystallization, respectively. The analysis of different contributions to peak broadening in [0 b 0] direction showed a similar trend for the crystallite sizes with the lower lattice microstrains after 2 days of synthesis. The effect similar to the preferred orientation was observed and classified with the Harris method.

  10. Controllability of brushite structural parameters using an applied magnetic field.

    PubMed

    Kuznetsov, V N; Yanovska, A A; Stanislavov, A S; Danilchenko, S N; Kalinkevich, A N; Sukhodub, L F

    2016-03-01

    The paper studies the influence of low intensity static magnetic field on brushite structural and microstructural parameters using the X-ray diffraction and the transmission electron microscopy. This effect was shown to have various influences on DCPD (Dicalcium Phosphate Dihydrate) structure depending on a magnetic field configuration or time of synthesis, which allows achieving controllability of the main properties of an obtained material. The influence of the magnetic field leads mostly to the decrease of crystallite sizes with no impact on the crystal lattice parameters. In (0 2 0) and (1 5 0) planes the growth of crystallite sizes is observed after 2 and 3 days of crystallization, respectively. The analysis of different contributions to peak broadening in [0 b 0] direction showed a similar trend for the crystallite sizes with the lower lattice microstrains after 2 days of synthesis. The effect similar to the preferred orientation was observed and classified with the Harris method. PMID:26706562

  11. Pulsating jet-like structures in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Goncharov, V. P.; Pavlov, V. I.

    2016-08-01

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as "radio pulsars." The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

  12. Edge Plasma Structure with Rotating Resonant Magnetic Perturbations at TEXTOR

    NASA Astrophysics Data System (ADS)

    Stoschus, H.; Schmitz, O.; Frerichs, H.; Lehnen, M.; Reiser, D.; Unterberg, B.; Samm, U.; Textor Research Team

    2011-10-01

    Rotating Resonant Magnetic Perturbations impose a characteristic modulation to the electron density and temperature in the TEXTOR plasma edge (r / a > 0 . 9). The modulation matches the position of the magnetic topology modeled in vacuum approximation for low relative rotation of frel = - 0 . 2 kHz between RMP field and toroidal plasma rotation. With increasing relative rotation (frel = 1 . 8 kHz), the plasma structure at the outermost rational flux surface is shifted by π / 2 in counter-Bt direction due to internal plasma response. The shift is correlated to a smaller displacement of the plasma structure in front of the RMP coils of 0 . 1 π . This indicates a competition between the near-field of the RMP coils and the net magnetic field at the rational flux surface. Work supported in part by US DOE under DE-AC05-06OR23100.

  13. A magnetically levitated synchronous permanent magnet planar motor with concentric structure winding used for lithography machine

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Kou, Baoquan; Xing, Feng; Jin, Yinxi; Zhang, Hailin; Zhu, Jianguo

    2015-05-01

    A novel magnetically levitated synchronous permanent magnet planar motor (MLSPMPM) with concentric structure winding, which can be used in lithography machine, is proposed in this paper. Topology and principle of the new MLSPMPM are introduced. The scalar magnetic potential is used to solve the magnetic system, and the differential equations are solved by the separation of variables method according to the boundary conditions. Characteristics, such as flux density, electromagnetic force, and back-EMF of the MLSPMPM, are obtained analytically. All of the results are validated by the finite element method. A prototype of the MLSPMPM is manufactured. Based on the prototype motor, some experiments are carried out. The measured results are used to showcase the validity of the analytical analysis.

  14. Possible magnetic structures of EuZrO3

    NASA Astrophysics Data System (ADS)

    Hu, Ai-Yuan; Qin, Guo-Ping; Wu, Zhi-Min; Cui, Yu-Ting

    2015-06-01

    A comprehensive research of the antiferromagnetic (AFM) structures of perovskite-type EuZrO3 is carried out by use of the double-time Green’s function. Two possible types of AFM configurations are considered, and theoretical results are compared with experimental results to extract the values of parameters J1, J2, and D. The obtained exchanges are employed to calculate the magnetic susceptibility, which is then in turn compared with the experimental one. Therefore, we think that the magnetic structure of EuZrO3 may be an isotropic G-type structure or an anisotropic A-type structure. Project supported by the National Natural Science Foundation of China (Grant Nos. 11404046, 11347217, and 61201119), the Basic Research Foundation of Chongqing Education Committee, China (Grant No. KJ130615), and the Chongqing Science & Technology Committee, China (Grant Nos. cstc2014jcyjA50013 and cstc2013jjB50001).

  15. Superconducting magnetic energy storage apparatus structural support system

    DOEpatents

    Withers, Gregory J.; Meier, Stephen W.; Walter, Robert J.; Child, Michael D.; DeGraaf, Douglas W.

    1992-01-01

    A superconducting magnetic energy storage apparatus comprising a cylindrical superconducting coil; a cylindrical coil containment vessel enclosing the coil and adapted to hold a liquid, such as liquefied helium; and a cylindrical vacuum vessel enclosing the coil containment vessel and located in a restraining structure having inner and outer circumferential walls and a floor; the apparatus being provided with horizontal compression members between (1) the coil and the coil containment vessel and (2) between the coil containment vessel and the vacuum vessel, compression bearing members between the vacuum vessel and the restraining structure inner and outer walls, vertical support members (1) between the coil bottom and the coil containment vessel bottom and (2) between the coil containment vessel bottom and the vacuum vessel bottom, and external supports between the vacuum vessel bottom and the restraining structure floor, whereby the loads developed by thermal and magnetic energy changes in the apparatus can be accommodated and the structural integrity of the apparatus be maintained.

  16. New magnetic structures in novel and conventional manganites

    NASA Astrophysics Data System (ADS)

    Daoud-Aladine, Aziz; Rodríguez-Carvajal, Juan; Perca, Cristian; Pinsard-Gaudart, Loreynne

    2011-03-01

    The determination of the magnetic structures of manganites has always been at the root of their fundamental understanding. We studied the magnetic structures of half-doped charge ordered manganites that are either show the prototype CE-type magnetic structure (Pr 1/2 Ca 1/2 Mn O3), or variants of this order (YBaMn 2 O6 and Pr 0.6 Ca 0.4 Mn O3) with neutron diffraction. The study of Pr 1/2 Ca 1/2 Mn O3 (ILL, France) is the first ever done on a single crystal and it essentially confirms the pioneering picture, whereas the NPD studies of YBaMn 2 O6 (PSI, Switzerland) and Pr 0.6 Ca 0.4 Mn O3 (ISIS, UK), give two unprecedented results. The YBaMn 2 O6 magnetic structure corroborates the hotly debated ordering of Zener Polarons, and high resolution NPD data evidence a new spin reorientation transition around T ~ 20 K far below its TN ~ 170 K in Pr 0.6 Ca 0.4 Mn O3 that has so far only been vaguely observed. We will discuss the consequences that these results have on the still hotly debated understanding of the connection between charge/orbital and spin orderings in the manganites.

  17. Structural and magnetic characterization of YIG particles prepared using microemulsions

    NASA Astrophysics Data System (ADS)

    Baldomir, D.; Teijeiro, A. G.; Rivas, J.; Vaqueiro, P.; Paz, S. B.; López Quintela, A.

    1995-02-01

    Yttrium-iron-garnet (YIG) particles have been synthesized using the microemulsion technique. A comparison of ferrite powders obtained by this method and those prepared by sol-gel and solid state reactions is reported. We have studied both the magnetic and structural properties and have found a dependence on annealing temperatures.

  18. Structures and magnetic properties of Co-Zr-B magnets studied by first-principles calculations

    DOE PAGES

    Zhao, Xin; Ke, Liqin; Nguyen, Manh Cuong; Wang, Cai -Zhuang; Ho, Kai -Ming

    2015-06-23

    The structures and magnetic properties of Co-Zr-B alloys near the composition of Co5Zr with B at. % ≤6% were studied using adaptive genetic algorithm and first-principles calculations. The energy and magnetic moment contour maps as a function of chemical composition were constructed for the Co-Zr-B magnet alloys through extensive structure searches and calculations. We found that Co-Zr-B system exhibits the same structure motif as the “Co11Zr2” polymorphs, and such motif plays a key role in achieving strong magnetic anisotropy. Boron atoms were found to be able to substitute cobalt atoms or occupy the “interruption” sites. First-principles calculations showed that themore » magnetocrystalline anisotropy energies of the boron-doped alloys are close to that of the high-temperature rhombohedral Co5Zr phase and larger than that of the low-temperature Co5.25Zr phase. As a result, our calculations provide useful guidelines for further experimental optimization of the magnetic performances of these alloys.« less

  19. Structures and magnetic properties of Co-Zr-B magnets studied by first-principles calculations

    SciTech Connect

    Zhao, Xin; Ke, Liqin; Nguyen, Manh Cuong; Wang, Cai -Zhuang; Ho, Kai -Ming

    2015-06-23

    The structures and magnetic properties of Co-Zr-B alloys near the composition of Co5Zr with B at. % ≤6% were studied using adaptive genetic algorithm and first-principles calculations. The energy and magnetic moment contour maps as a function of chemical composition were constructed for the Co-Zr-B magnet alloys through extensive structure searches and calculations. We found that Co-Zr-B system exhibits the same structure motif as the “Co11Zr2” polymorphs, and such motif plays a key role in achieving strong magnetic anisotropy. Boron atoms were found to be able to substitute cobalt atoms or occupy the “interruption” sites. First-principles calculations showed that the magnetocrystalline anisotropy energies of the boron-doped alloys are close to that of the high-temperature rhombohedral Co5Zr phase and larger than that of the low-temperature Co5.25Zr phase. As a result, our calculations provide useful guidelines for further experimental optimization of the magnetic performances of these alloys.

  20. Structures and magnetic properties of Co-Zr-B magnets studied by first-principles calculations

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Ke, Liqin; Nguyen, Manh Cuong; Wang, Cai-Zhuang; Ho, Kai-Ming

    2015-06-01

    The structures and magnetic properties of Co-Zr-B alloys near the composition of Co5Zr with B at. % ≤6% were studied using adaptive genetic algorithm and first-principles calculations. The energy and magnetic moment contour maps as a function of chemical composition were constructed for the Co-Zr-B magnet alloys through extensive structure searches and calculations. We found that Co-Zr-B system exhibits the same structure motif as the "Co11Zr2" polymorphs, and such motif plays a key role in achieving strong magnetic anisotropy. Boron atoms were found to be able to substitute cobalt atoms or occupy the "interruption" sites. First-principles calculations showed that the magnetocrystalline anisotropy energies of the boron-doped alloys are close to that of the high-temperature rhombohedral Co5Zr phase and larger than that of the low-temperature Co5.25Zr phase. Our calculations provide useful guidelines for further experimental optimization of the magnetic performances of these alloys.

  1. Magnetic domain structure and magnetization reversal in submicron-scale Co dots

    SciTech Connect

    Fernandez, A., LLNL

    1998-02-17

    We present a magnetic force microscopy (MFM) analysis of arrays of submicron-scale Co dots fabricated by interference lithography. The dots are thin (180-300 A) and are elliptical in shape. MFM of these structures reveals that they relax into highly ordered remanent states whose symmetry and configuration are governed by their shape anisotropy. In particular, when the dots are saturated along the easy-axis, a uniformly magnetized state persists at remanence. However, when the dots are saturated in hard-axis, they relax into a single-vortex state in which the circulation can have either sign. Both remanent states are characterized by smoothly varying magnetization patterns and a high degree of uniformity across the array. We attribute the ordered behavior of these structures to the film microstructure, which allows the shape anisotropy to dominate over magnetocrystalline anisotropy. By imaging a series of minor-loop remanent states, we show that magnetization reversal in these structures occurs via the nucleation and annihilation of a single vortex. Magnetic hysteresis loop measurements are consistent with these observations and provide additional details. Furthermore, we present the results of micromagnetic simulations, which are in excellent agreement with both the MFM images and the hysteresis loop measurements.

  2. Magnetic domain structure and magnetization reversal in submicron-scale Co dots

    SciTech Connect

    Cerjan, C J; Fernandez, A; Gibbons, M; Wall, M A

    1998-09-24

    We present a magnetic force microscopy (MFM) analysis of arrays of submicron-scale Co dots fabricated by interference lithography. The dots are thin (180--300 Å) and elliptical in shape. MFM reveals that these structures relax into highly ordered remanent states whose symmetry and configuration are governed by their shape anisotropy. In particular, when the dots are saturated along their long-axis, a uniformly magnetized state persists at remanence. However, when the dots are saturated along their short-axis, they relax into a single-vortex state in which the circulation can have either sign. Both states are characterized by smoothly varying magnetization patterns and a high degree of uniformity across the array. We attribute the ordered behavior of these.structures to the film microstructure, which allows the shape anisotropy to dominate over magnetocrystalline anjsotropy. By imaging a series of minor-loop remanent states, we show that magnetization reversal in these structures occurs via the nucleation and annihilation of a single vortex. Magnetic hysteresis loop measurements are consistent with these observations and provide additional details. Furthermore, we present the results of micromagnetic simulations, which are in excellent agreement with both the MFM images and the hysteresis loop measurements. © 1998 Elsevier Science B.V. All rights reserved.

  3. Structures and magnetic properties of Co-Zr-B magnets studied by first-principles calculations

    SciTech Connect

    Zhao, Xin; Ke, Liqin; Nguyen, Manh Cuong; Wang, Cai-Zhuang Ho, Kai-Ming

    2015-06-28

    The structures and magnetic properties of Co-Zr-B alloys near the composition of Co{sub 5}Zr with B at. % ≤6% were studied using adaptive genetic algorithm and first-principles calculations. The energy and magnetic moment contour maps as a function of chemical composition were constructed for the Co-Zr-B magnet alloys through extensive structure searches and calculations. We found that Co-Zr-B system exhibits the same structure motif as the “Co{sub 11}Zr{sub 2}” polymorphs, and such motif plays a key role in achieving strong magnetic anisotropy. Boron atoms were found to be able to substitute cobalt atoms or occupy the “interruption” sites. First-principles calculations showed that the magnetocrystalline anisotropy energies of the boron-doped alloys are close to that of the high-temperature rhombohedral Co{sub 5}Zr phase and larger than that of the low-temperature Co{sub 5.25}Zr phase. Our calculations provide useful guidelines for further experimental optimization of the magnetic performances of these alloys.

  4. Anisotropic magnetic properties and magnetic structure of YbPdSi

    NASA Astrophysics Data System (ADS)

    Tsujii, Naohito; Keller, Lukas; Dönni, Andreas; Kitazawa, Hideaki

    2016-08-01

    YbPdSi with orthorhombic crystal structure (space group Pmmn) exhibits a magnetic transition at {{T}\\text{m}}=8 K, below which a ferromagnetic moment develops with an enhanced electronic specific-heat coefficient γ ∼ 200 mJ K‑2 mol‑1. We have investigated the magnetization, electrical resistivity, and specific heat of YbPdSi using single crystalline samples as functions of temperature and magnetic field. It has been found that the ferromagnetic moment points to the c-direction, although the magnetic moments have an Ising-like anisotropy along the b-direction above the magnetic-transition temperature. Field dependence of the magnetization and electrical resistivity shows a metamagnetic-like transition at {{H}\\text{m}}=0.3 T when field is applied along the b-axis below T  =  3 K, suggesting the existence of an antiferromagnetic component along this direction. The magnetic structure has been investigated by neutron diffraction using powder samples. The magnetic unit cell is identical to the crystal unit cell. The Rietveld fitting has revealed that Yb at the 2a and 2b positions exhibit a collinear ferromagnetic order along the c-axis, whereas Yb at the 4e position undergoes a non-collinear order, involving the ferromagnetic moment along the c-axis and an antiferromagnetic component along the b-axis. The ferromagnetic moments determined by the neutron diffraction are 0.26, 1.3, and 0.15 {μ\\text{B}} for Yb at the 4e, 2b, and 2a sites, respectively. The reduced moments for the 4e and the 2a sites suggest that the Kondo screening effect is important in YbPdSi.

  5. Structural and functional MRI abnormalities of cerebellar cortex and nuclei in SCA3, SCA6 and Friedreich's ataxia.

    PubMed

    Stefanescu, Maria R; Dohnalek, Moritz; Maderwald, Stefan; Thürling, Markus; Minnerop, Martina; Beck, Andreas; Schlamann, Marc; Diedrichsen, Joern; Ladd, Mark E; Timmann, Dagmar

    2015-05-01

    type 3. Within the cerebellar nuclei, reductions were significant when comparing spinocerebellar ataxia type 6 and Friedreich's ataxia to matched controls (P < 0.01, bootstrap-corrected cluster-size threshold; two-sample t-tests). Susceptibility weighted imaging allowed depiction of atrophy of the cerebellar nuclei in patients with Friedreich's ataxia and spinocerebellar ataxia type 3. In spinocerebellar ataxia type 6, pathology was not restricted to the cerebellar cortex but also involved the cerebellar nuclei. Functional magnetic resonance imaging data, on the other hand, revealed that pathology in Friedreich's ataxia and spinocerebellar ataxia type 3 is not restricted to the cerebellar nuclei. There was functional involvement of the cerebellar cortex despite no or little structural changes.

  6. Structure of a Magnetic Flux Annihilation Layer Formed by the Collision of Supersonic, Magnetized Plasma Flows

    NASA Astrophysics Data System (ADS)

    Suttle, L. G.; Hare, J. D.; Lebedev, S. V.; Swadling, G. F.; Burdiak, G. C.; Ciardi, A.; Chittenden, J. P.; Loureiro, N. F.; Niasse, N.; Suzuki-Vidal, F.; Wu, J.; Yang, Q.; Clayson, T.; Frank, A.; Robinson, T. S.; Smith, R. A.; Stuart, N.

    2016-06-01

    We present experiments characterizing the detailed structure of a current layer, generated by the collision of two counterstreaming, supersonic and magnetized aluminum plasma flows. The antiparallel magnetic fields advected by the flows are found to be mutually annihilated inside the layer, giving rise to a bifurcated current structure—two narrow current sheets running along the outside surfaces of the layer. Measurements with Thomson scattering show a fast outflow of plasma along the layer and a high ion temperature (Ti˜Z ¯ Te , with average ionization Z ¯=7 ). Analysis of the spatially resolved plasma parameters indicates that the advection and subsequent annihilation of the inflowing magnetic flux determines the structure of the layer, while the ion heating could be due to the development of kinetic, current-driven instabilities.

  7. Magnetic Field Sensing Based on Magnetic-Fluid-Clad Multimode-Singlemode-Multimode Fiber Structures

    PubMed Central

    Tang, Jiali; Pu, Shengli; Dong, Shaohua; Luo, Longfeng

    2014-01-01

    Magnetic field sensing based on magnetic-fluid-clad multimode-singlemode-multimode fiber structures is proposed and experimentalized. The structures are fabricated out using fiber fusion splicing techniques. The sensing principle is based on the interference between the core mode and cladding modes. Two interference dips are observed in our spectral range. Experimental results indicate that the magnetic field sensing sensitivities of 215 pm/mT and 0.5742 dB/mT are obtained for interference dip around 1595 nm. For interference dip around 1565 nm, the sensitivities are 60.5 pm/mT and 0.4821 dB/mT. The response of temperature is also investigated. The temperature sensitivity for the dip around 1595 nm is obtained to be 9.93 pm/°C. PMID:25317761

  8. Structure-induced spin reorientation in magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Neumann, Alexander; Frauen, Axel; Vollmers, Julian; Meyer, Andreas; Oepen, Hans Peter

    2016-09-01

    We report on structuring-induced changes of the magnetic anisotropy of cylindrical nanostructures which are carved out of thin Pt/Co/Pt films. The magnetic properties of films and structures with a diameter of about 34 nm were investigated via magneto-optic Kerr effect. The magnetic anisotropy is determined for both films and nanostructures for varying Co thicknesses (0.5-7 nm). In general, the nanostructures exhibit larger perpendicular anisotropy than the films. On thickness increase of the Co layer two spin reorientation transitions at about 2.2 and 5 nm are found. At 2.2 nm the nanostructures exhibit the transition from perpendicular to in-plane orientation of magnetization while at 5 nm the reversed transition is found. The variation of the magnetic anisotropy of the Co nanostructures is not solely caused by the change of shape anisotropy. The net change, corrected for the shape, reveals a reduction of strain in the thinnest Co layers while the increase of the anisotropy of the nanostructures at higher Co thicknesses is caused by a transformation of the Co lattice from fcc to hcp.

  9. Structural origin of low temperature glassy relaxation in magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Laha, Suvra; Regmi, Rajesh; Lawes, Gavin

    2013-03-01

    Magnetic nanoparticles often exhibit glass-like relaxation features at low temperatures. Here we discuss the effects of doping boron, cobalt, gadolinium and lanthanum on the low temperature magnetic properties of Fe3O4 nanoparticles. We investigated the structure of the nanoparticles using both X-ray diffraction and Raman studies, and find evidence for secondary phase formation in certain samples. We acquired Transmission Electron Microscopic images to give direct information on the morphology and microstructure of these doped nanoparticles. We measured the ac out-of-phase susceptibility (χ//) vs temperature (T) to parameterize the low temperature glassy magnetic relaxation. All samples show low temperature magnetic relaxation, but the amplitude of the signal increases dramatically for certain dopants. We attribute these low temperature frequency-dependent magnetic relaxation features to structural defects, which are enhanced in some of the doped Fe3O4 nanoparticles. These studies also confirm that the low temperature relaxation in nanoparticles arises from single particle effects and are not associated with interparticle interactions.

  10. Growth-related magnetic and physical structures in CMR films

    SciTech Connect

    Hawley, M.E.; Brown, G.W.; Hundley, M.F.

    1997-09-01

    Scanning tunneling microscopy (STM), atomic force microscopy (AFM), and magnetic force microscopy (MFM) have proven to be powerful tools for revealing property-sensitive structures in magnetic materials. With the renewed interest in perovskite films as materials for read-heads in high density magnetic data storage, the same challenges faced by high temperature superconductor (HTS) film fabrication are repeated for these materials. To begin addressing these challenges, we used vapor phase epitaxy to fabricate La (Sr, Ca,) based manganate films on single crystal perovskite substrates under different conditions and characterized them with scanning probe microscopies, x-ray diffraction, and temperature-dependent magnetization and resistivity measurements (M(T) and {rho}(T)). The as-grown films were polygranular with grain sizes increasing with increasing temperature (T). The post-deposition annealed films consisted of coalesced layers with improved transport properties. The room temperature magnetic structure of the Sr-based films appeared to be related to defects and/or strain.

  11. Concentric Magnetic Structures for Magnetophoretic Bead Collection, Cell Trapping and Analysis of Cell Morphological Changes Caused by Local Magnetic Forces

    PubMed Central

    Huang, Chen-Yu; Wei, Zung-Hang

    2015-01-01

    Concentric magnetic structures (ring and square) with domain wall (DW) pinning geometry are designed for biological manipulation. Magnetic beads collection was firstly demonstrated to analyse the local magnetic field generated by DWs and the effective regions to capture magnetic targets of size 1 μm. Primary mouse embryonic fibroblasts (MEFs) are magnetically labeled by internalizing poly (styrene sulfonic acid) stabilized magnetic nanoparticles (PSS-MNPs) and then are selectively trapped by head-to-tail DWs (HH DWs) or tail-to-tail DWs (TT DWs) to be arranged into linear shape or cross shape. The morphologies and the nuclear geometry of the cells growing on two kinds of concentric magnetic structures are shown to be distinctive. The intracellular magnetic forces generated by the local magnetic field of DWs are found to influence the behaviour of cells. PMID:26270332

  12. Magnetic resonance in a Cu-Cr-S structure

    SciTech Connect

    Vorotynov, A. M. Abramova, G. M.; Pankrats, A. I.; Petrakovskii, G. A.; Zharkov, S. M.; Zeer, G. M.; Tugarinov, V. I.; Rautskii, M. V.; Sokolov, V. V.

    2013-11-15

    A layered Cu-Cr-S structure composed of single-crystal CuCrS{sub 2} layers and thin CuCr{sub 2}S{sub 4} plates embedded in them has been investigated by the magnetic resonance and scanning electron microscopy methods. The Curie temperature and saturation magnetization of the spinel phase of the investigated samples have been determined. The thickness of the CuCr{sub 2}S{sub 4} layers has been estimated. The dependence of the growncrystal topology on synthesis conditions has been established. An interpretation of the anomalous behavior of the magnetostatic oscillation intensity is offered.

  13. Structuring Light by Concentric-Ring Patterned Magnetic Metamaterial Cavities.

    PubMed

    Zeng, Jinwei; Gao, Jie; Luk, Ting S; Litchinitser, Natalia M; Yang, Xiaodong

    2015-08-12

    Ultracompact and tunable beam converters pose a significant potential for modern optical technologies ranging from classical and quantum communication to optical manipulation. Here we design and demonstrate concentric-ring patterned structures of magnetic metamaterial cavities capable of tailoring both polarization and phase of light by converting circularly polarized light into a vector beam with an orbital angular momentum. We experimentally illustrate the realization of both radially and azimuthally polarized vortex beams using such concentric-ring patterned magnetic metamaterials. These results contribute to the advanced complex light manipulation with optical metamaterials, making it one step closer to realizing the simultaneous control of polarization and orbital angular momentum of light on a chip.

  14. Ulysses Data Analysis: Magnetic Topology of Heliospheric Structures

    NASA Technical Reports Server (NTRS)

    Crooker, Nancy

    2001-01-01

    In this final technical report on research funded by a NASA grant, a project overview is given by way of summaries on nine published papers. Research has included: 1) Using suprathermal electron data to study heliospheric magnetic structures; 2) Analysis of magnetic clouds, coronal mass ejections (CME), and the heliospheric current sheet (HCS); 3) Analysis of the corotating interaction region (CIR) which develop from interactions between solar wind streams of different velocities; 4) Use of Ulysses data in the interpretation of heliospheric events and phenomena.

  15. Electronic structure and magnetic properties of zigzag blue phosphorene nanoribbons

    SciTech Connect

    Hu, Tao; Hong, Jisang

    2015-08-07

    We investigated the electronic structure and magnetism of zigzag blue phosphorene nanoribbons (ZBPNRs) using first principles density functional theory calculations by changing the widths of ZBPNRs from 1.5 to 5 nm. In addition, the effect of H and O passivation was explored as well. The ZBPNRs displayed intra-edge antiferromagnetic ground state with a semiconducting band gap of ∼0.35 eV; and this was insensitive to the edge structure relaxation effect. However, the edge magnetism of ZBPNRs disappeared with H-passivation. Moreover, the band gap of H-passivated ZBPNRs was greatly enhanced because the calculated band gap was ∼1.77 eV, and this was almost the same as that of two-dimensional blue phosphorene layer. For O-passivated ZBPNRs, we also found an intra-edge antiferromagnetic state. Besides, both unpassivated and O-passivated ZBPNRs preserved almost the same band gap. We predict that the electronic band structure and magnetic properties can be controlled by means of passivation. Moreover, the edge magnetism can be also modulated by the strain. Nonetheless, the intrinsic physical properties are size independent. This feature can be an advantage for device applications because it may not be necessary to precisely control the width of the nanoribbon.

  16. The Origins of Magnetic Structure in the Corona and Wind

    NASA Technical Reports Server (NTRS)

    Antiochos, Spiro K.

    2010-01-01

    One of the most important and most puzzling features of the coronal magnetic field is that it appears to have smooth magnetic structure with little evidence for non-potentiality except at two special locations: photospheric polarity inversions lines. (non-potentiality observed as a filament channel) and coronal hole boundaries, (observed as the slow solar wind). This characteristic feature of the closed-field corona is highly unexpected given that its magnetic field is continuously tangled by photospheric motions. Although reconnection can eliminate some of the injected structure, it cannot destroy the helicity, which should build up to produce observable complexity. I propose that an inverse cascade process transports the injected helicity from the interior of closed flux regions to their boundaries inversion lines and coronal holes, creating both filament channels and the slow wind. We describe how the helicity is injected and transported and calculate the relevant rates. I argue that one process, helicity transport, can explain both the observed lack and presence of structure in the coronal magnetic field. This work has been supported by the NASA HTP, SR&T, and LWS programs.

  17. Magnetic and structural instabilities of ultrathin Fe(100) wedges

    SciTech Connect

    Bader, S.D.; Li, Dongqi; Qiu, Z.Q.

    1994-05-01

    An overview is provided of recent efforts to explore magnetic and related structural issues for ultrathin Fe films grown epitaxially as wedge structures onto Ag(100) and Cu(100). Experiments were carried out utilizing the surface magneto-optic Kerr effect (SMOKE). Ordinary bcc Fe is lattice-matched to the primitive unit cell of the Ag(100) surface. Fe wedges on Ag(100) can be fabricated whose thick end has in-plane magnetic easy axes due to the shape anisotropy, and whose thin end has perpendicular easy axes due to the surface magnetic anisotrophy. A spin-reorientation transition can thus be studied in the center of the wedge where the competing anisotropies cancel. The goal is to test the Mermin-Wagner theorem which states that long-range order is lost at finite temperatures in an isotropic two-dimensional Heisenberg system. Fe wedges on Cu(100) can be studied in like manner, but the lattice matching permits fcc and tetragonally-distorted fcc phases to provide structural complexity in addition to the interplay of competing magnetic anisotropies. The results of these studies are new phase identifications that help both to put previous work into perspective and to define issues to pursue in the future.

  18. Magnetic field and electric current structure in the chromosphere

    NASA Technical Reports Server (NTRS)

    Dravins, D.

    1974-01-01

    The three-dimensional vector magnetic field structure in the chromosphere above an active region is deduced by using high-resolution H-alpha filtergrams together with a simultaneous digital magnetogram. An analog model of the field is made with 400 metal wires representing field lines that outline the H-alpha structure. The height extent of the field is determined from vertical field-gradient observations around sunspots, from observed fibril heights, and from an assumption that the sources of the field are largely local. The computed electric currents (typically 10 mA/sq m) are found to flow in patterns not similar to observed features and not parallel to magnetic fields. Force structures correspond to observed solar features; the dynamics to be expected include: downward motion in bipolar areas in the lower chromosphere, an outflow of the outer chromosphere into the corona with radially outward flow above bipolar plage regions, and motion of arch filament systems.

  19. Effective field model of roughness in magnetic nano-structures

    SciTech Connect

    Lepadatu, Serban

    2015-12-28

    An effective field model is introduced here within the micromagnetics formulation, to study roughness in magnetic structures, by considering sub-exchange length roughness levels as a perturbation on a smooth structure. This allows the roughness contribution to be separated, which is found to give rise to an effective configurational anisotropy for both edge and surface roughness, and accurately model its effects with fine control over the roughness depth without the explicit need to refine the computational cell size to accommodate the roughness profile. The model is validated by comparisons with directly roughened structures for a series of magnetization switching and domain wall velocity simulations and found to be in excellent agreement for roughness levels up to the exchange length. The model is further applied to vortex domain wall velocity simulations with surface roughness, which is shown to significantly modify domain wall movement and result in dynamic pinning and stochastic creep effects.

  20. Magnetic Field Structure of Pressure Balanced Structures from Ulysses High Latitudes Observations

    NASA Technical Reports Server (NTRS)

    Yamauchi, Y.; Suess, S. T.; Sakurai, T.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Ulysses observations showed that pressure balance structures (PBSs) are a common feature in the high-latitude solar winds near the solar minimum. On the other hand, coronal plumes are common in polar coronal holes near the solar minimum. It is therefore considered that the PBSs would be remnants of plumes. Several detailed studies of the PBSs have been made from Ulysses/SWOOPS observations, but study of their magnetic structures has not yet been done. The study of the magnetic structure is important because previous observations and theoretical models of plumes indicate that they are related to the network activity such as magnetic reconnection on the photosphere. We have investigated the magnetic structures of the PBSs with Ulysses magnetometer and SWOOPS data. We have found that magnetic reversals in radial magnetic field take place while the spacecraft passes through most of the PBSs These magnetic reversals have been interpreted as large amplitude Alfv/'enic fluctuations but our results suggest that Ulysses is also traversing current sheets of plasmoids associated with network activity at the base of plumes.

  1. Abnormal Degree Centrality of Bilateral Putamen and Left Superior Frontal Gyrus in Schizophrenia with Auditory Hallucinations: A Resting-state Functional Magnetic Resonance Imaging Study

    PubMed Central

    Chen, Cheng; Wang, Hui-Ling; Wu, Shi-Hao; Huang, Huan; Zou, Ji-Lin; Chen, Jun; Jiang, Tian-Zi; Zhou, Yuan; Wang, Gao-Hua

    2015-01-01

    Background: Dysconnectivity hypothesis of schizophrenia has been increasingly emphasized. Recent researches showed that this dysconnectivity might be related to occurrence of auditory hallucination (AH). However, there is still no consistent conclusion. This study aimed to explore intrinsic dysconnectivity pattern of whole-brain functional networks at voxel level in schizophrenic with AH. Methods: Auditory hallucinated patients group (n = 42 APG), no hallucinated patients group (n = 42 NPG) and normal controls (n = 84 NCs) were analyzed by resting-state functional magnetic resonance imaging. The functional connectivity metrics index (degree centrality [DC]) across the entire brain networks was calculated and evaluated among three groups. Results: DC decreased in the bilateral putamen and increased in the left superior frontal gyrus in all the patients. However, in APG, the changes of DC were more obvious compared with NPG. Symptomology scores were negatively correlated with the DC of bilateral putamen in all patients. AH score of APG positively correlated with the DC in left superior frontal gyrus but negatively correlated with the DC in bilateral putamen. Conclusion: Our findings corroborated that schizophrenia was characterized by functional dysconnectivity, and the abnormal DC in bilateral putamen and left superior frontal gyrus might be crucial in the occurrence of AH. PMID:26612293

  2. Magnetic structures of actinide materials by pulsed neutron diffraction

    SciTech Connect

    Lawson, A.C.; Goldstone, J.A.; Huber, J.G.; Giorgi, A.L.; Conant, J.W.; Severing, A.; Cort, B.; Robinson, R.A.

    1990-01-01

    We describe some attempts to observe magnetic structure in various actinide (5f-electron) materials. Our experimental technique is neutron powder diffraction as practiced at a spallation (pulsed) neutron source. We will discuss our investigations of {alpha}-Pu, {delta}-Pu, {alpha}-UD{sub 3} and {beta}-UD{sub 3}. {beta}-UD{sub 3} is a simple ferromagnet: surprisingly, the moments on the two non-equivalent uranium atoms are the same within experimental error. {alpha}-UD{sub 3}, {alpha}-Pu and {delta}-Pu are non-magnetic, within the limits of our observations. Our work with pulsed neutron diffraction shows that it is a useful technique for research on magnetic materials.

  3. Magnetic apatite for structural insights on the plasma membrane.

    PubMed

    Stanca, Sarmiza E; Müller, Robert; Dellith, Jan; Nietzsche, Sandor; Stöckel, Stephan; Biskup, Christoph; Deckert, Volker; Krafft, Christoph; Popp, Jürgen; Fritzsche, Wolfgang

    2015-01-21

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications.

  4. Magnetic apatite for structural insights on the plasma membrane

    NASA Astrophysics Data System (ADS)

    Stanca, Sarmiza E.; Müller, Robert; Dellith, Jan; Nietzsche, Sandor; Stöckel, Stephan; Biskup, Christoph; Deckert, Volker; Krafft, Christoph; Popp, Jürgen; Fritzsche, Wolfgang

    2015-01-01

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications.

  5. Nanoscale Magnetic Structure of Ferromagnet/Antiferromagnet Manganite Multilayers

    SciTech Connect

    Niebieskikwiat, D.; Hueso, L. E.; Borchers, J. A.; Mathur, N. D.; Salamon, M. B.

    2007-12-14

    We use polarized neutron reflectometry and dc magnetometry to obtain a comprehensive picture of the magnetic structure of a series of La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/Pr{sub 2/3}Ca{sub 1/3}MnO{sub 3} (LSMO/PCMO) superlattices, with varying thickness of the antiferromagnetic (AFM) PCMO layers (0{<=}t{sub A}{<=}7.6 nm). While LSMO presents a few magnetically frustrated monolayers at the interfaces with PCMO, in the latter a magnetic contribution due to ferromagnetic (FM) inclusions within the AFM matrix is maximized at t{sub A}{approx}3 nm. This enhancement of FM moment occurs at the matching between layer thickness and cluster size, implying the possibility of tuning phase separation by imposing appropriate geometrical constraints which favor the accommodation of FM nanoclusters within the ''non-FM'' material.

  6. Ichthyosis in Sjögren-Larsson syndrome reflects defective barrier function due to abnormal lamellar body structure and secretion.

    PubMed

    Rizzo, William B; S'Aulis, Dana; Jennings, M Anitia; Crumrine, Debra A; Williams, Mary L; Elias, Peter M

    2010-08-01

    Sjögren-Larsson syndrome is a genetic disease characterized by ichthyosis, mental retardation, spasticity and mutations in the ALDH3A2 gene coding for fatty aldehyde dehydrogenase, an enzyme necessary for oxidation of fatty aldehydes and fatty alcohols. We investigated the cutaneous abnormalities in 9 patients with Sjögren-Larsson syndrome to better understand how the enzymatic deficiency results in epidermal dysfunction. Histochemical staining for aldehyde oxidizing activity was profoundly reduced in the epidermis. Colloidal lanthanum perfusion studies showed abnormal movement of tracer into the extracellular spaces of the stratum corneum consistent with a leaky water barrier. The barrier defect could be attributed to the presence of abnormal lamellar bodies, many with disrupted limiting membranes or lacking lamellar contents. Entombed lamellar bodies were present in the cytoplasm of corneocytes suggesting blockade of lamellar body secretion. At the stratum granulosum-stratum corneum interface, non-lamellar material displaced or replaced secreted lamellar membranes, and in the stratum corneum, the number of lamellar bilayers declined and lamellar membrane organization was disrupted by foci of lamellar/non-lamellar phase separation. These studies demonstrate the presence of a permeability barrier abnormality in Sjögren-Larsson syndrome, which localizes to the stratum corneum interstices and can be attributed to abnormalities in lamellar body formation and secretion.

  7. Studying Autism Spectrum Disorder with Structural and Diffusion Magnetic Resonance Imaging: A Survey

    PubMed Central

    Ismail, Marwa M. T.; Keynton, Robert S.; Mostapha, Mahmoud M. M. O.; ElTanboly, Ahmed H.; Casanova, Manuel F.; Gimel'farb, Georgy L.; El-Baz, Ayman

    2016-01-01

    Magnetic resonance imaging (MRI) modalities have emerged as powerful means that facilitate non-invasive clinical diagnostics of various diseases and abnormalities since their inception in the 1980s. Multiple MRI modalities, such as different types of the sMRI and DTI, have been employed to investigate facets of ASD in order to better understand this complex syndrome. This paper reviews recent applications of structural magnetic resonance imaging (sMRI) and diffusion tensor imaging (DTI), to study autism spectrum disorder (ASD). Main reported findings are sometimes contradictory due to different age ranges, hardware protocols, population types, numbers of participants, and image analysis parameters. The primary anatomical structures, such as amygdalae, cerebrum, and cerebellum, associated with clinical-pathological correlates of ASD are highlighted through successive life stages, from infancy to adulthood. This survey demonstrates the absence of consistent pathology in the brains of autistic children and lack of research investigations in patients under 2 years of age in the literature. The known publications also emphasize advances in data acquisition and analysis, as well as significance of multimodal approaches that combine resting-state, task-evoked, and sMRI measures. Initial results obtained with the sMRI and DTI show good promise toward the early and non-invasive ASD diagnostics. PMID:27242476

  8. Low-degree Structure in Mercury's Planetary Magnetic Field

    NASA Technical Reports Server (NTRS)

    Anderson, Brian J.; Johnson, Catherine L.; Korth, Haje; Winslow, Reka M.; Borovsky, Joseph E.; Purucker, Michael E.; Slavin, James A.; Solomon, Sean C.; Zuber, Maria T.; McNutt, Ralph L. Jr.

    2012-01-01

    The structure of Mercury's internal magnetic field has been determined from analysis of orbital Magnetometer measurements by the MESSENGER spacecraft. We identified the magnetic equator on 531 low-altitude and 120 high-altitude equator crossings from the zero in the radial cylindrical magnetic field component, Beta (sub rho). The low-altitude crossings are offset 479 +/- 6 km northward, indicating an offset of the planetary dipole. The tilt of the magnetic pole relative to the planetary spin axis is less than 0.8 deg.. The high-altitude crossings yield a northward offset of the magnetic equator of 486 +/- 74 km. A field with only nonzero dipole and octupole coefficients also matches the low-altitude observations but cannot yield off-equatorial Beta (sub rho) = 0 at radial distances greater than 3520 km. We compared offset dipole and other descriptions of the field with vector field observations below 600 km for 13 longitudinally distributed, magnetically quiet orbits. An offset dipole with southward directed moment of 190 nT-R-cube (sub M) yields root-mean-square (RMS) residuals below 14 nT, whereas a field with only dipole and octupole terms tuned to match the polar field and the low-altitude magnetic equator crossings yields RMS residuals up to 68 nT. Attributing the residuals from the offset-dipole field to axial degree 3 and 4 contributions we estimate that the Gauss coefficient magnitudes for the additional terms are less than 4% and 7%, respectively, relative to the dipole. The axial alignment and prominent quadrupole are consistent with a non-convecting layer above a deep dynamo in Mercury's fluid outer core.

  9. Structural and magnetic properties of nickel antimony ferrospinels

    SciTech Connect

    Ivanov, S. A.; Tellgren, R.; Porcher, F.; Andre, G.; Ericsson, T.; Nordblad, P; Sadovskaya, N.; Kaleva, G.; Politova, E.; Baldini, M.; Sun, C.; Arvanitis, D.; Kumar, P. Anil; Mathieu, R.

    2015-05-05

    Spinel-type compounds of Fe–Ni–Sb–O system were synthesized as polycrystalline powders. The crystal and magnetic properties were investigated using X-ray and neutron powder diffraction, Mössbauer and X-ray absorption spectroscopy and magnetization measurements. The samples crystallize in the cubic system, space group Fd – 3 m. The distribution of cations between octahedral and tetrahedral sites was refined from the diffraction data sets using constraints imposed by the magnetic, Mössbauer and EDS results and the ionic radii. The cation distribution and the temperature dependence of the lattice parameter (a) and the oxygen positional parameter (u) were obtained. A chemical formula close to Fe0.8Ni1.8Sb0.4O4 was determined, with Sb5+ cations occupying octahedral sites, and Fe3+ and Ni2+ occupying both tetrahedral and octahedral sites. Fe3+ mainly (85/15 ratio) occupy tetrahedral sites, and conversely Ni2+ mainly reside on octahedral ones. The magnetic unit cell is the same as the crystallographic one, having identical symmetry relations. The results indicate that the compounds have a collinear ferrimagnetic structure with antiferromagnetic coupling between the tetrahedral (A) and octahedral (B) sites. Uniquely, the temperature dependence of the net magnetization of this rare earth free ferrimagnet exhibits a compensation point.

  10. Magnetic Structure and Formation of On-disk Coronal Plumes

    NASA Astrophysics Data System (ADS)

    Antonsson, S.; Tiwari, S. K.; Moore, R. L.; Winebarger, A. R.

    2015-12-01

    "Plumes" are feather-like features found on the solar disk, in the plage-like field concentrations of quiet regions. On-disk plumes are analogous to polar/coronal-hole plumes but have not been studied in detail in the past. We research their formation and characteristics, such as lifetime, intensity and magnetic setting at the feet. Atmospheric Imaging Assembly (AIA) images in the 171 Å filter and Helioseismic and Magnetic Imager (HMI) line-of-sight magnetograms, both from the Solar Dynamics Observatory (SDO), are analyzed with the IDL SolarSoftWare package and used to study the plumes. We find that on-disk plumes form at the places of converging magnetic fields, and disappear when those fields disperse. However, plumes disappear after nearby events, such as flares, or with the emergence of opposite polarity. The lifetime of each plume tends to be several days, although some appear and disappear within several hours. On-disk plumes outline magnetic fields close to the sun, allowing a better understanding of fine magnetic structures than before. Additionally, since plumes must be heated to around 600,000 K to be visible in 171 Å, their formation and characteristics could tell about how they, and therefore the corona, are heated.

  11. Magnetic monopole interactions: shell structure of meson and baryon states

    SciTech Connect

    Akers, D.

    1986-12-01

    It is suggested that a low-mass magnetic monopole of Dirac charge g = (137/2)e may be interacting with a c-quark's magnetic dipole moment to produce Zeeman splitting of meson states. The mass M/sub 0/ = 2397 MeV of the monopole is in contrast to the 10/sup 16/-GeV monopoles of grand unification theories (GUT). It is shown that shell structure of energy E/sub n/ = M/sub 0/ + 1/4nM/sub 0/... exists for meson states. The presence of symmetric meson states leads to the identification of the shell structure. The possible existence of the 2397-MeV magnetic monopole is shown to quantize quark masses in agreement with calculations of quantum chromodynamics (QCD). From the shell structure of meson states, the existence of two new mesons is predicted: eta(1814 +/- 50 MeV) with I/sup G/(J/sup PC/) = 0/sup +/(0/sup - +/) and eta/sub c/ (3907 +/- 100 MeV) with J/sup PC/ = 0/sup - +/. The presence of shell structure for baryon states is shown.

  12. The interplanetary magnetic structure that guides solar relativistic particles

    NASA Astrophysics Data System (ADS)

    Masson, S.; Démoulin, P.; Dasso, S.; Klein, K.-L.

    2012-02-01

    Context. Relating in-situ measurements of relativistic solar particles to their parent activity in the corona requires understanding the magnetic structures that guide them from their acceleration site to the Earth. Relativistic particle events are observed at times of high solar activity, when transient magnetic structures such as interplanetary coronal mass ejections (ICMEs) often shape the interplanetary magnetic field (IMF). They may introduce interplanetary paths that are longer than nominal, and magnetic connections rooted far from the nominal Parker spiral. Aims: We present a detailed study of the IMF configurations during ten relativistic solar particle events of the 23rd activity cycle to elucidate the actual IMF configuration that guides the particles to the Earth, where they are measured by neutron monitors. Methods: We used magnetic field (MAG) and plasma parameter measurements (SWEPAM) from the ACE spacecraft and determined the interplanetary path lengths of energetic particles through a modified version of the velocity dispersion analysis based on energetic particle measurements with SoHO/ERNE. Results: We find that the majority (7/10) of the events is detected in the vicinity of an ICME. Their interplanetary path lengths are found to be longer (1.5-2.6 AU) than those of the two events propagating in the slow solar wind (1.3 AU). The longest apparent path length is found in an event within the fast solar wind, probably caused by enhanced pitch angle scattering. The derived path lengths imply that the first energetic and relativistic protons are released at the Sun at the same time as electron beam emitting type III radio bursts. Conclusions: The timing of the first high-energy particle arrival on Earth is mainly determined by the type of IMF in which the particles propagate. Initial arrival times are as expected from Parker's model in the slow solar wind, and significantly longer in or near transient structures such as ICMEs.

  13. Ultrafine metallic Fe nanoparticles: synthesis, structure and magnetism

    PubMed Central

    Margeat, Olivier; Lecante, Pierre; Chaudret, Bruno

    2010-01-01

    Summary The results of the investigation of the structural and magnetic (static and dynamic) properties of an assembly of metallic Fe nanoparticles synthesized by an organometallic chemical method are described. These nanoparticles are embedded in a polymer, monodisperse, with a diameter below 2 nm, which corresponds to a number of around 200 atoms. The X-ray absorption near-edge structure and Mössbauer spectrum are characteristic of metallic Fe. The structural studies by wide angle X-ray scattering indicate an original polytetrahedral atomic arrangement similar to that of β-Mn, characterized by a short-range order. The average magnetic moment per Fe atom is raised to 2.59 µB (for comparison, bulk value of metallic Fe: 2.2 µB). Even if the spontaneous magnetization decreases rapidly as compared to bulk materials, it remains enhanced even up to room temperature. The gyromagnetic ratio measured by ferromagnetic resonance is of the same order as that of bulk Fe, which allows us to conclude that the orbital and spin contributions increase at the same rate. A large magnetic anisotropy for metallic Fe has been measured up to (3.7 ± 1.0)·105 J/m3. Precise analysis of the low temperature Mössbauer spectra, show a broad distribution of large hyperfine fields. The largest hyperfine fields display the largest isomer shifts. This indicates a progressive increase of the magnetic moment inside the particle from the core to the outer shell. The components corresponding to the large hyperfine fields with large isomer shifts are indeed characteristic of surface atoms. PMID:21977400

  14. Shifting the Starspot Paradigm: Imaging Global Magnetic Structures

    NASA Astrophysics Data System (ADS)

    Roettenbacher, Rachael M.; Monnier, John D.

    2016-01-01

    Stellar magnetism exists in stars across the HR diagram and fuels stellar activity (e.g. flares and starspots). This magnetism affects measurements of fundamental stellar parameters, such as radius and temperature, leading to inaccurate mass and age estimates. In order to better determine stellar parameters, we aim to understand how magnetically-suppressed convection presents as cool regions across the stellar surface. In the standard "spot paradigm" of localized starspots blemishing an otherwise featureless surface, we use precision Kepler data and light curve inversion to study stellar differential rotation and starspot evolution. Contrastingly, by imaging interferometric data collected with the Michigan Infrared Combiner (MIRC) at GSU's Center for High Angular Resolution Astronomy (CHARA) Array, we detect large-scale magnetic structures across the surface of ζ Andromedae. These global regions of suppressed convection cover a large fraction of the surface, likely changing the atmospheric structure of the photosphere and impacting stellar parameter estimates. The large-scale features are at best ambiguous to interpret via established techniques that rely on rotational modulation of spots (e.g. light curve inversion and Doppler imaging). We seek to identify a class of targets where the "spot paradigm" breaks down and gives new insights into a range of phenomena such as long-term changes in flux for active stars, anomalous proper motion of spots derived from precision photometry, and the nature of the stellar dynamo of stars with large convective envelopes.

  15. High frequency magnetization dynamics of ferromagnetic nano-structures

    NASA Astrophysics Data System (ADS)

    Zohar, Sioan

    effects of magnetization motion in opposite layers of a NiFe/Cu/CoZr "spin valve" have been isolated using ultrafast time-resolved x-ray magnetic circular dichroism (TR-XMCD), a layer-specific probe of dynamics. We first describe our instrumental advances in TR-XMCD, in which we have applied synchronous detection techniques to speed data acquisition, enabling measurements of weak coupling. In these measurements, we observe the CoZr responds to the NiFe precession with an in phase component, typically attributed to interlayer dipolar coupling, and a pi/2 out of phase component which has been attributed to coupling via pure spin currents. We estimate an effective interface mixing conductance of g↑↓eff of 8.68 +/- 1.74 nm-2, very close to what has been observed in epitaxial Fe-based structures. This identification is made subject to the assumption of a phase offset in the Co layer precession, not explained at present. We close with experiments demonstrating the feasibility of TR-XMCD in sub-micron and patterned structures. Synchronous detection techniques have been applied for the first time to measure domain wall motion in micron scale Ni81Fe19 squares.

  16. Double-flat-spiral magnetic structures: Theory and application to the RMn6X6 compounds

    NASA Astrophysics Data System (ADS)

    Rosenfeld, E. V.; Mushnikov, N. V.

    2008-05-01

    We studied magnetic structure of a layered magnetic material, the lattice of which consists of magnetic layers separated by alternating non-magnetic layers (slabs) of two different types. For such structure, the exchange integrals between the nearest magnetic layers separated by different slabs may have different values, while the next-nearest neighbor exchange integral is the same for all magnetic layers. We developed a model based on three different interlayer exchange integrals. In the framework of this model we analyzed conditions of the appearance of a magnetic structure of the double-flat-spiral type and its distortion in external magnetic field. The results are most obtained in the analytical form. The model was applied to analyze the magnetic structure and magnetization process of the RMn6X6 ( R=Y, Sc, Lu; X=Sn, Ge) compounds with the layered crystal structure.

  17. Effect of substrate rotation on domain structure and magnetic relaxation in magnetic antidot lattice arrays

    SciTech Connect

    Mallick, Sougata; Mallik, Srijani; Bedanta, Subhankar

    2015-08-28

    Microdimensional triangular magnetic antidot lattice arrays were prepared by varying the speed of substrate rotation. The pre-deposition patterning has been performed using photolithography technique followed by a post-deposition lift-off. Surface morphology taken by atomic force microscopy depicted that the growth mechanism of the grains changes from chain like formation to island structures due to the substrate rotation. Study of magnetization reversal via magneto optic Kerr effect based microscopy revealed reduction of uniaxial anisotropy and increase in domain size with substrate rotation. The relaxation measured under constant magnetic field becomes faster with rotation of the substrate during deposition. The nature of relaxation for the non-rotating sample can be described by a double exponential decay. However, the relaxation for the sample with substrate rotation is well described either by a double exponential or a Fatuzzo-Labrune like single exponential decay, which increases in applied field.

  18. Magnetic structure and magnetic transport properties of graphene nanoribbons with sawtooth zigzag edges.

    PubMed

    Wang, D; Zhang, Z; Zhu, Z; Liang, B

    2014-12-23

    The magnetic structure and magnetic transport properties of hydrogen-passivated sawtooth zigzag-edge graphene nanoribbons (STGNRs) are investigated theoretically. It is found that all-sized ground-state STGNRs are ferromagnetic and always feature magnetic semiconductor properties, whose spin splitting energy gap E(g) changes periodically with the width of STGNRs. More importantly, for the STGNR based device, the dual spin-filtering effect with the perfect (100%) spin polarization and high-performance dual spin diode effect with a rectification ratio about 10(10) can be predicted. Particularly, a highly effective spin-valve device is likely to be realized, which displays a giant magnetoresistace (MR) approaching 10(10)%, which is three orders magnitude higher than the value predicted based on the zigzag graphene nanoribbons and six orders magnitude higher than previously reported experimental values for the MgO tunnel junction. Our findings suggest that STGNRs might hold a significant promise for developing spintronic devices.

  19. Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy in Dementias

    PubMed Central

    Hsu, Yuan-Yu; Du, An-Tao; Schuff, Norbert; Weiner, Michael W.

    2007-01-01

    This article reviews recent studies of magnetic resonance imaging and magnetic resonance spectroscopy in dementia, including Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, idiopathic Parkinson's disease, Huntington's disease, and vascular dementia. Magnetic resonance imaging and magnetic resonance spectroscopy can detect structural alteration and biochemical abnormalities in the brain of demented subjects and may help in the differential diagnosis and early detection of affected individuals, monitoring disease progression, and evaluation of therapeutic effect. PMID:11563438

  20. FLOWS AND WAVES IN BRAIDED SOLAR CORONAL MAGNETIC STRUCTURES

    SciTech Connect

    Pant, V.; Datta, A.; Banerjee, D.

    2015-03-01

    We study the high frequency dynamics in the braided magnetic structure of an active region (AR 11520) moss as observed by the High-Resolution Coronal Imager (Hi-C). We detect quasi-periodic flows and waves in these structures. We search for high frequency dynamics while looking at power maps of the observed region. We find that shorter periodicities (30–60 s) are associated with small spatial scales which can be resolved by Hi-C only. We detect quasi-periodic flows with a wide range of velocities, from 13–185 km s{sup −1}, associated with braided regions. This can be interpreted as plasma outflows from reconnection sites. We also find short period and large amplitude transverse oscillations associated with the braided magnetic region. Such oscillations could be triggered by reconnection or such oscillations may trigger reconnection.

  1. Structural, optical, and magnetic properties of FeVO3

    NASA Astrophysics Data System (ADS)

    Singh, Pooja; Gupta, Anurag; Dogra, Anjana

    2016-05-01

    We report the structural, optical, and magnetic properties of polycrystalline FeVO3 synthesized by solid state reaction technique.While FeVO3 has rhombohedral crystal structure with space group R-3c (167) identical to the parentα-Fe2O3, the lattice volume reduces due to the replacement of Fe3+ with V3+ having smaller ionic radii. The most remarkable outcome of doping is reduction in band gap from 2.1 (α-Fe2O3) to 1.5 eV (FeVO3), which is favorable for photo-electrochemical applications. Although the canted ferromagnetism persists in FeVO3, an enhancement in magnetic moment is observed as compared to the parent compound.

  2. Mirror domain structures induced by interlayer magnetic wall coupling.

    PubMed

    Lew, W S; Li, S P; Lopez-Diaz, L; Hatton, D C; Bland, J A C

    2003-05-30

    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. PMID:12786582

  3. Geometric, electronic, and magnetic structure of FexOy+ clusters

    NASA Astrophysics Data System (ADS)

    Logemann, R.; de Wijs, G. A.; Katsnelson, M. I.; Kirilyuk, A.

    2015-10-01

    Correlation between geometry, electronic structure, and magnetism of solids is both intriguing and elusive. This is particularly strongly manifested in small clusters, where a vast number of unusual structures appear. Here, we employ density functional theory in combination with a genetic search algorithm GGA +U and a hybrid functional to determine the structure of gas phase FexOy+/0 clusters. For FexOy+ cation clusters we also calculate the corresponding vibration spectra and compare them with experiments. We successfully identify Fe3O4+ , Fe4O5+ , Fe4O6+ , Fe5O7+ and propose structures for Fe6O8+ . Within the triangular geometric structure of Fe3O4+ , a noncollinear, ferrimagnetic, and ferromagnetic state are comparable in energy. Fe4O5+ and Fe4O6+ are ferrimagnetic with a residual magnetic moment of 1 μB due to ionization. Fe5O7+ is ferrimagnetic due to the odd number of Fe atoms. We compare the electronic structure with bulk magnetite and find Fe4O5+ , Fe4O6+ , Fe6O8+ to be mixed valence clusters. In contrast, in Fe3O4+ and Fe5O7+ , all Fe are found to be trivalent.

  4. MAGNETIC STRUCTURE OF RAPIDLY ROTATING FK COMAE-TYPE CORONAE

    SciTech Connect

    Cohen, O.; Drake, J. J.; Kashyap, V. L.; Korhonen, H.; Elstner, D.; Gombosi, T. I.

    2010-08-10

    We present a three-dimensional simulation of the corona of an FK Com-type rapidly rotating G giant using a magnetohydrodynamic model that was originally developed for the solar corona in order to capture the more realistic, non-potential coronal structure. We drive the simulation with surface maps for the radial magnetic field obtained from a stellar dynamo model of the FK Com system. This enables us to obtain the coronal structure for different field topologies representing different periods of time. We find that the corona of such an FK Com-like star, including the large-scale coronal loops, is dominated by a strong toroidal component of the magnetic field. This is a result of part of the field being dragged by the radial outflow, while the other part remains attached to the rapidly rotating stellar surface. This tangling of the magnetic field, in addition to a reduction in the radial flow component, leads to a flattening of the gas density profile with distance in the inner part of the corona. The three-dimensional simulation provides a global view of the coronal structure. Some aspects of the results, such as the toroidal wrapping of the magnetic field, should also be applicable to coronae on fast rotators in general, which our study shows can be considerably different from the well-studied and well-observed solar corona. Studying the global structure of such coronae should also lead to a better understanding of their related stellar processes, such as flares and coronal mass ejections, and in particular should lead to an improved understanding of mass and angular momentum loss from such systems.

  5. Magnetic properties and magnetic domain structure of grain-oriented Fe-3%Si steel under compression

    NASA Astrophysics Data System (ADS)

    Perevertov, O.; Schäfer, R.

    2016-09-01

    The influence of an applied compressive stress on the magnetic properties and domain structure in Goss-textured (110) [001] Fe-3%Si steel is studied. The magnetic domains and magnetization processes were observed by longitudinal Kerr microscopy at different levels of compressive stress. With stress increase the domain structure without applied field evolves from 180° slab-like domains along the surface-parallel easy axis first into stress pattern I, then into the checkerboard pattern and finally into stress pattern II, in which all internal domains are oriented along the transverse axes. The magnetization process under compression is realized by surface closure [001] domains that grow into the bulk at the expense of transverse domains. The domain evolution by these three stress patterns is not practically noticeable in hysteresis curves above 10 MPa—they change continuously with the same effective field being valid for curves from 10 to 67 MPa. The comparison with previous measurements under different stress/cutting angle combinations shows that for the prediction of a constricted hysteresis loop it is sufficient to consider the energy difference between surface-parallel and transverse easy axes neglecting details of the spatial organization of transverse domains.

  6. Magnetic and Structural Properties of Ultra-Thin Cobalt Films

    NASA Astrophysics Data System (ADS)

    Wiedmann, Michael Helmut

    In situ polar Kerr effect measurements have been used to study the magnetic anisotropy of Au(111)/Co/X, Pd(111)/Co/X, Cu(111)/Co/X, and Pd(100)/Co/X sandwiches, where X is the nonmagnetic metal Ag, Au, Cu, Ir, and Pd or the insulator MgO. The films were grown by molecular beam epitaxy (MBE). For the metals, we found that the magnitude of the Co/X perpendicular interface anisotropy is strongly peaked at ~1 atomic layer (1.5-2.5 A) coverage. To investigate structural influences on the anisotropy, we have used reflection high energy diffraction (RHEED) and low energy electron diffraction (LEED) to measure changes resulting from overlayer coverage. Analysis of digitized RHEED images captured every ~ 1 A during metal overlayer coverage shows no abrupt change of the in-plane lattice constant. We have also investigated the out-of-plane lattice spacing as a function of nonmagnetic metal coverage by measuring LEED I-V curves along the (0,0) rod. In the case of Cu, where the LEED behavior is nearly kinematic, we see no evidence of any abrupt structural changes at ~1 atomic layer coverage. These results suggest the observed peak in magnetic anisotropy is not structural in origin. The influence of an insulating overlayer, MgO, on the perpendicular magnetic properties was also investigated.

  7. Structural Image Analysis of the Brain in Neuropsychology Using Magnetic Resonance Imaging (MRI) Techniques.

    PubMed

    Bigler, Erin D

    2015-09-01

    Magnetic resonance imaging (MRI) of the brain provides exceptional image quality for visualization and neuroanatomical classification of brain structure. A variety of image analysis techniques provide both qualitative as well as quantitative methods to relate brain structure with neuropsychological outcome and are reviewed herein. Of particular importance are more automated methods that permit analysis of a broad spectrum of anatomical measures including volume, thickness and shape. The challenge for neuropsychology is which metric to use, for which disorder and the timing of when image analysis methods are applied to assess brain structure and pathology. A basic overview is provided as to the anatomical and pathoanatomical relations of different MRI sequences in assessing normal and abnormal findings. Some interpretive guidelines are offered including factors related to similarity and symmetry of typical brain development along with size-normalcy features of brain anatomy related to function. The review concludes with a detailed example of various quantitative techniques applied to analyzing brain structure for neuropsychological outcome studies in traumatic brain injury.

  8. Interplay between structural symmetry and magnetism in Ag-Cu

    NASA Astrophysics Data System (ADS)

    Yen, Tsung-Wen; Lai, S. K.

    2016-01-01

    We present first-principles theoretical calculations of the magnetic properties of bimetallic clusters Ag-Cu. The calculations proceeded by combining a previously developed state-of-the-art optimization algorithm (P.J. Hsu, S.K. Lai, J. Chem. Phys. 124 (2006) 0447110) with an empirical potential and applied this numerical scheme to determine first the lowest energy structures of pure clusters Ag38 and Cu38, and also their different atomic compositions AgnCu38-n for n=1,2,…,37. Then, we carried out the Kohn-Sham spin unrestricted density functional theory calculations on the optimized atomic structures obtained in the preceding step. Given the minimized structures from the first step as input configurations, the results of these re-optimized structures by full density functional theory calculations yield more refined electronic and atomic structures. A thorough comparison of the structural differences between these two sets of atomic geometries, one from using an empirical potential in which the electronic degrees of freedom were included approximately and another from subsequent minimization using the spin unrestricted density functional theory, sheds light on how the electronic charges disperse near atoms in clusters AgnCu38-n, and hence the distributions of electronic spin and charge densities at re-optimized sites of the cluster. These data of the electronic dispersion and the ionic configuration give clue to the mystery of the unexpected net magnetic moments which were found in some of the clusters AgnCu38-n at n=1-4, 24 as well as the two pure clusters. Possible origins for this unanticipated magnetism were explained in the context of the point group theory in much the same idea as the Clemenger-Nilsson model applied to simple metal clusters except that we draw particular attention to the atomic topologies and stress the bearing that they have on valence electrons in inducing them to disperse and occupy different molecular orbital energy levels.

  9. Structure and magnetism in Cr-embedded Co nanoparticles.

    PubMed

    Baker, S H; Kurt, M S; Roy, M; Lees, M R; Binns, C

    2016-02-01

    We present the results of an investigation into the atomic structure and magnetism of 2 nm diameter Co nanoparticles embedded in an antiferromagnetic Cr matrix. The nanocomposite films used in this study were prepared by co-deposition directly from the gas phase, using a gas aggregation source for the Co nanoparticles and a molecular beam epitaxy (MBE) source for the Cr matrix material. Co K and Cr K edge extended x-ray absorption fine structure (EXAFS) experiments were performed in order to investigate atomic structure in the embedded nanoparticles and matrix respectively, while magnetism was investigated by means of a vibrating sample magnetometer. The atomic structure type of the Co nanoparticles is the same as that of the Cr matrix (bcc) although with a degree of disorder. The net Co moment per atom in the Co/Cr nanocomposite films is significantly reduced from the value for bulk Co, and decreases as the proportion of Co nanoparticles in the film is decreased; for the sample with the most dilute concentration of Co nanoparticles (4.9% by volume), the net Co moment was 0.25 μ B/atom. After field cooling to below 30 K all samples showed an exchange bias, which was largest for the most dilute sample. Both the structural and magnetic results point towards a degree of alloying at the nanoparticle/matrix interface, leading to a core/shell structure in the embedded nanoparticles consisting of an antiferromagnetic CoCr alloy shell surrounding a reduced ferromagnetic Co core.

  10. Structural, electronic, and magnetic characteristics of Np2Co17

    NASA Astrophysics Data System (ADS)

    Halevy, I.; Hen, A.; Orion, I.; Colineau, E.; Eloirdi, R.; Griveau, J.-C.; Gaczyński, P.; Wilhelm, F.; Rogalev, A.; Sanchez, J.-P.; Winterrose, M. L.; Magnani, N.; Shick, A. B.; Caciuffo, R.

    2012-01-01

    A previously unknown neptunium-transition-metal binary compound Np2Co17 has been synthesized and characterized by means of powder x-ray diffraction, 237Np Mössbauer spectroscopy, superconducting-quantum-interference-device magnetometry, and x-ray magnetic circular dichroism (XMCD). The compound crystallizes in a Th2Ni17-type hexagonal structure with room-temperature lattice parameters a=8.3107(1) Å and c=8.1058(1) Å. Magnetization curves indicate the occurrence of ferromagnetic order below TC>350 K. Mössbauer spectra suggest a Np3+ oxidation state and give an ordered moment of μNp=1.57(4) μB and μNp=1.63(4) μB for the Np atoms located, respectively, at the 2b and 2d crystallographic positions of the P63/mmc space group. Combining these values with a sum-rule analysis of the XMCD spectra measured at the neptunium M4,5 absorption edges, one obtains the spin and orbital contributions to the site-averaged Np moment [μS=-1.88(9) μB, μL=3.48(9) μB]. The ratio between the expectation value of the magnetic-dipole moment and the spin magnetic moment (mmd/μS=+1.36) is positive as predicted for localized 5f electrons and lies between the values calculated in intermediate-coupling (IC) and jj approximations. The expectation value of the angular part of the spin-orbit-interaction operator is in excellent agreement with the IC estimate. The ordered moment averaged over the four inequivalent Co sites, as obtained from the saturation value of the magnetization, is μCo≃1.6 μB. The experimental results are discussed against the predictions of first-principles electronic-structure calculations based on the spin-polarized local-spin-density approximation plus the Hubbard interaction.

  11. Magnetic mirror structure for testing shell-type quadrupole coils

    SciTech Connect

    Andreev, N.; Barzi, E.; Bossert, R.; Chlachidze, G.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; Tartaglia, N.; Turrioni, D.; /Fermilab

    2009-10-01

    This paper presents magnetic and mechanical designs and analyses of the quadrupole mirror structure to test single shell-type quadrupole coils. Several quadrupole coils made of different Nb{sub 3}Sn strands, cable insulation and pole materials were tested using this structure at 4.5 and 1.9 K. The coils were instrumented with voltage taps, spot heaters, temperature sensors and strain gauges to study their mechanical and thermal properties and quench performance. The results of the quadrupole mirror model assembly and test are reported and discussed.

  12. Non-superconducting magnet structures for near-term, large fusion experimental devices

    SciTech Connect

    File, J.; Knutson, D.S.; Marino, R.E.; Rappe, G.H.

    1980-10-01

    This paper describes the magnet and structural design in the following American tokamak devices: the Princeton Large Torus (PLT), the Princeton Divertor Experiment (PDX), and the Tokamak Fusion Test Reactor (TFTR). The Joint European Torus (JET), also presented herein, has a magnet structure evolved from several European programs and, like TFTR, represents state of the art magnet and structure design.

  13. Solitary waves and nonlinear dynamic coherent structures in magnetic metamaterials

    NASA Astrophysics Data System (ADS)

    Tankeyev, A. P.; Smagin, V. V.; Borich, M. A.; Zhuravlev, A. S.

    2009-03-01

    Within the framework of the extended nonlinear Schrödinger equation (ENSE), two types of nonlinear states of magnetization in a ferromagnet-dielectric-metal metamagnetic structure have been obtained and investigated. These states have an internal structure; e.g., a periodic sequence of compound solitons is formed by kink-antikink pairs (shock waves), and coherent periodic breather structures are formed by “bright” quasi-solitons. Conditions have been found under which the envelope of these states is described by a modified Korteweg-de Vries (mKdV) equation. It is shown that the compound solitons are described by an mKdV equation with repulsion, and the breather structures, by an mKdV equation with attraction. It is shown also that the characteristic properties of the solutions are determined by the sign of the group-velocity dispersion rather than by the sign of the group velocity itself. The results obtained can be used for searching new nonlinear dynamic coherent structures, e.g., compound solitons and breathers in high-dispersion magnetic metamaterials.

  14. Progressive Transformation between Two Magnetic Ground States for One Crystal Structure of a Chiral Molecular Magnet.

    PubMed

    Li, Li; Nishihara, Sadafumi; Inoue, Katsuya; Kurmoo, Mohamedally

    2016-03-21

    We report the exceptional observation of two different magnetic ground states (MGS), spin glass (SG, T(B) = 7 K) and ferrimagnet (FI, T(C) = 18 K), for one crystal structure of [{Mn(II)(D/L-NH2ala)}3{Mn(III)(CN)6}]·3H2O obtained from [Mn(CN)6](3-) and D/L-aminoalanine, in contrast to one MGS for [{Mn(II)(L-NH2ala)}3{Cr(III)(CN)6}]·3H2O. They consist of three Mn(NH2ala) helical chains bridged by M(III)(CN)6 to give the framework with disordered water molecules in channels and between the M(III)(CN)6. Both MGS are characterized by a negative Weiss constant, bifurcation in ZFC-FC magnetizations, blocking of the moments, both components of the ac susceptibilities, and hysteresis. They differ in the critical temperatures, absolute magnetization for 5 Oe FC (lack of spontaneous magnetization for the SG), and the shapes of the hysteresis and coercive fields. While isotropic pressure increases both T(crit) and the magnetizations linearly and reversibly in each case, dehydration progressively transforms the FI into the SG as followed by concerted in situ magnetic measurements and single-crystal diffraction. The relative strengths of the two moderate Mn(III)-CN-Mn(II) antiferromagnetic (J1 and J2), the weak Mn(II)-OCO-Mn(II) (J3), and Dzyaloshinkii-Moriya antisymmetric (DM) interactions generate the two sets of characters. Examination of the bond lengths and angles for several crystals and their corresponding magnetic properties reveals a correlation between the distortion of Mn(III)(CN)6 and the MGS. SG is favored by higher magnetic anisotropy by less distorted Mn(III)(CN)6 in good accordance with the Mn-Cr system. This conclusion is also born out of the magnetization measurements on orientated single crystals with fields parallel and perpendicular to the unique c axis of the hexagonal space group. PMID:26893217

  15. Epilepsy in the setting of full trisomy 18: A multicenter study on 18 affected children with and without structural brain abnormalities.

    PubMed

    Matricardi, Sara; Spalice, Alberto; Salpietro, Vincenzo; Di Rosa, Gabriella; Balistreri, Maria Cristina; Grosso, Salvatore; Parisi, Pasquale; Elia, Maurizio; Striano, Pasquale; Accorsi, Patrizia; Cusmai, Raffaella; Specchio, Nicola; Coppola, Giangennaro; Savasta, Salvatore; Carotenuto, Marco; Tozzi, Elisabetta; Ferrara, Pietro; Ruggieri, Martino; Verrotti, Alberto

    2016-09-01

    This paper reports on the clinical aspects, electroencephalographic (EEG) features, and neuroimaging findings in children with full trisomy 18 and associated epilepsy, and compares the evolution and outcome of their neurological phenotype. We retrospectively studied 18 patients (10 males and 8 females; aged 14 months to 9 years) with full trisomy 18 and epilepsy. All patients underwent comprehensive assessment including neuroimaging studies of the brain. We divided patients into two groups according to neuroimaging findings: (Group 1) 10 patients harboring structural brain malformations, and (Group 2) 8 patients with normal brain images. Group 1 had a significantly earlier age at seizure onset (2 months) compared to Group 2 (21 months). The seizure semiology was more severe in Group 1, who presented multiple seizure types, need for polytherapy (80% of patients), multifocal EEG abnormalities and poorer outcome (drug resistant epilepsy in 90% of patients) than Group 2 who presented a single seizure type, generalized or focal, and non-specific EEG pattern; these patients were successfully treated with monotherapy with good outcome. Imaging revealed a wide and complex spectrum of structural brain abnormalities including anomalies of the commissures, cerebellar malformations, cortical abnormalities, and various degrees of cortical atrophy. Epilepsy in full trisomy 18 may develop during the first months of life and can be associated with structural brain malformations. Patients with brain malformations can show multiple seizure types and can frequently be resistant to therapy with antiepileptic drugs. © 2016 Wiley Periodicals, Inc. PMID:27519909

  16. Structural and magnetic relaxations of mechanically alloyed Fe-Mo

    NASA Astrophysics Data System (ADS)

    Jiraskova, Y.; Bursik, J.; Turek, I.; Cizek, J.; Prochazka, I.

    2014-10-01

    The Fe-Mo sample mechanically alloyed for 250 h under air atmosphere was exposed to a series of isothermal and isochronal treatments with the aim to follow changes in the structure and magnetic properties regarding relaxations of strains and defects and stability of chemical composition. For this purpose x-ray diffraction, positron annihilation, scanning and transmission electron microscopy, and Mössbauer spectrometry were applied and supplemented by magnetic measurements. The temperatures for the magnetic studies were selected from the thermomagnetic curve of the as-prepared sample. The time interval of isothermal treatments was chosen from 0-300 min. The Mo content in the bcc-Fe(Mo) phase has substantially exceeded the equilibrium solubility limit but it has been found to decrease under the thermal treatment which was reflected by decreasing lattice parameters. The small crystallite size of approximately 10 nm in the initial state starts to grow only after a certain amount of strains induced by severe deformation, due to mechanical alloying being released. This was also reflected in the magnetic parameters. From their time dependences at selected temperatures the characteristic relaxation times were obtained and used for a calculation of the activation enthalpy of relaxation processes.

  17. CHARACTERISTIC DEPENDENCE OF UMBRAL DOTS ON THEIR MAGNETIC STRUCTURE

    SciTech Connect

    Watanabe, H.; Kitai, R.; Ichimoto, K.

    2009-09-10

    Umbral dots (UDs) were observed in a stable sunspot in NOAA 10944 by the Hinode Solar Optical Telescope on 2007 March 1. The observation program consisted of blue continuum images and spectropolarimetric profiles of Fe I 630 nm line. An automatic detection algorithm for UDs was applied to the 2 hr continuous blue continuum images, and using the obtained data, the lifetime, size, and proper motion of UDs were calculated. The magnetic structure of the sunspot was derived through the inversion of the spectropolarimetric profiles. We calculated the correlations between UD's parameters (size, lifetime, occurrence rate, proper motion) and magnetic fields (field strength, inclination, azimuth), and obtained the following results. (1) Both the lifetime and size of UDs are almost constant regardless of the magnetic field strength at their emergence site. (2) The speed of UDs increases as the field inclination angle at their emergence site gets larger. (3) The direction of movement of UDs is nearly parallel to the direction of the horizontal component of magnetic field in the region with strongly inclined field, while UDs in the region with weakly inclined field show virtually no proper motion. Our results describe the basic properties of magnetoconvection in sunspots. We will discuss our results in comparison to recent magnetohydrodynamic simulations by Schuessler and Voegler and Rempel et al.

  18. Nano-structured magnetic metamaterial with enhanced nonlinear properties

    PubMed Central

    Kobljanskyj, Yuri; Melkov, Gennady; Guslienko, Konstantin; Novosad, Valentyn; Bader, Samuel D.; Kostylev, Michael; Slavin, Andrei

    2012-01-01

    Nano-structuring can significantly modify the properties of materials. We demonstrate that size-dependent modification of the spin-wave spectra in magnetic nano-particles can affect not only linear, but also nonlinear magnetic response. The discretization of the spectrum removes the frequency degeneracy between the main excitation mode of a nano-particle and the higher spin-wave modes, having the lowest magnetic damping, and reduces the strength of multi-magnon relaxation processes. This reduction of magnon-magnon relaxation for the main excitation mode leads to a dramatic increase of its lifetime and amplitude, resulting in the intensification of all the nonlinear processes involving this mode. We demonstrate this experimentally on a two-dimensional array of permalloy nano-dots for the example of parametric generation of a sub-harmonic of an external microwave signal. The characteristic lifetime of this sub-harmonic is increased by two orders of magnitude compared to the case of a continuous magnetic film, where magnon-magnon relaxation limits the lifetime. PMID:22745899

  19. Dynamical structure of magnetized dissipative accretion flow around black holes

    NASA Astrophysics Data System (ADS)

    Sarkar, Biplob; Das, Santabrata

    2016-09-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accretion solutions including shocks. We estimate the energy dissipation at the PSC from where a part of the accreting matter can deflect as outflows and jets. We compare the maximum energy that could be extracted from the PSC and the observed radio luminosity values for several supermassive black hole sources and the observational implications of our present analysis are discussed.

  20. Magnetic properties of dendrimer structures with different coordination numbers: A Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Masrour, R.; Jabar, A.

    2016-11-01

    We investigate the magnetic properties of Cayley trees of large molecules with dendrimer structure using Monte Carlo simulations. The thermal magnetization and magnetic susceptibility of a dendrimer structure are given with different coordination numbers, Z=3, 4, 5 and different generations g=3 and 2. The variation of magnetizations with the exchange interactions and crystal fields have been given of this system. The magnetic hysteresis cycles have been established.

  1. Structure of Prominence Legs: Plasma and Magnetic Field

    NASA Astrophysics Data System (ADS)

    Levens, P. J.; Schmieder, B.; Labrosse, N.; López Ariste, A.

    2016-02-01

    We investigate the properties of a “solar tornado” observed on 2014 July 15, and aim to link the behavior of the plasma to the internal magnetic field structure of the associated prominence. We made multi-wavelength observations with high spatial resolution and high cadence using SDO/AIA, the Interface Region Imaging Spectrograph (IRIS) spectrograph, and the Hinode/Solar Optical Telescope (SOT) instrument. Along with spectropolarimetry provided by the Télescope Héliographique pour l’Etude du Magnétisme et des Instabilités Solaires telescope we have coverage of both optically thick emission lines and magnetic field information. AIA reveals that the two legs of the prominence are strongly absorbing structures which look like they are rotating, or oscillating in the plane of the sky. The two prominence legs, which are both very bright in Ca ii (SOT), are not visible in the IRIS Mg ii slit-jaw images. This is explained by the large optical thickness of the structures in Mg ii, which leads to reversed profiles, and hence to lower integrated intensities at these locations than in the surroundings. Using lines formed at temperatures lower than 1 MK, we measure relatively low Doppler shifts on the order of ±10 km s-1 in the tornado-like structure. Between the two legs we see loops in Mg ii, with material flowing from one leg to the other, as well as counterstreaming. It is difficult to interpret our data as showing two rotating, vertical structures that are unrelated to the loops. This kind of “tornado” scenario does not fit with our observations. The magnetic field in the two legs of the prominence is found to be preferentially horizontal.

  2. Structure of Prominence Legs: Plasma and Magnetic Field

    NASA Astrophysics Data System (ADS)

    Levens, P. J.; Schmieder, B.; Labrosse, N.; López Ariste, A.

    2016-02-01

    We investigate the properties of a “solar tornado” observed on 2014 July 15, and aim to link the behavior of the plasma to the internal magnetic field structure of the associated prominence. We made multi-wavelength observations with high spatial resolution and high cadence using SDO/AIA, the Interface Region Imaging Spectrograph (IRIS) spectrograph, and the Hinode/Solar Optical Telescope (SOT) instrument. Along with spectropolarimetry provided by the Télescope Héliographique pour l’Etude du Magnétisme et des Instabilités Solaires telescope we have coverage of both optically thick emission lines and magnetic field information. AIA reveals that the two legs of the prominence are strongly absorbing structures which look like they are rotating, or oscillating in the plane of the sky. The two prominence legs, which are both very bright in Ca ii (SOT), are not visible in the IRIS Mg ii slit-jaw images. This is explained by the large optical thickness of the structures in Mg ii, which leads to reversed profiles, and hence to lower integrated intensities at these locations than in the surroundings. Using lines formed at temperatures lower than 1 MK, we measure relatively low Doppler shifts on the order of ±10 km s‑1 in the tornado-like structure. Between the two legs we see loops in Mg ii, with material flowing from one leg to the other, as well as counterstreaming. It is difficult to interpret our data as showing two rotating, vertical structures that are unrelated to the loops. This kind of “tornado” scenario does not fit with our observations. The magnetic field in the two legs of the prominence is found to be preferentially horizontal.

  3. A facile route to synthesize core/shell structured carbon/magnetic nanoparticles hybrid and their magnetic properties

    SciTech Connect

    Qi, Xiaosi; Xu, Jianle; Zhong, Wei; Du, Youwei

    2015-07-15

    Graphical abstract: Controllable synthesis of core/shell structured carbon/magnetic nanoparticles hybrid and their tunable magnetic properties. - Highlights: • The paper reports a simple route for core/shell structured carbon/magnetic nanoparticles hybrid. • By controlling the temperature, Fe{sub 3}O{sub 4}@CNCs, Fe@HCNTs and Fe@LCNTs were produced selectively. • The magnetic properties of the obtained core/shell structured hybrid could be tuned effectively. - Abstract: By controlling the pyrolysis temperature, core/shell structured Fe{sub 3}O{sub 4}/carbon nanocages, Fe/helical carbon nanotubes and Fe/low helicity of carbon nanotubes could be synthesized selectively over Fe{sub 2}O{sub 3} nanotubes generated by a hydrothermal method. The transmission electron microscopic and scanning electron microscopic investigations revealed that the efficiency of generating core/shell structured hybrid was high, exceeding 90%. Because of the magnetic nanoparticles tightly wrapped in graphitic layers, the obtained core/shell structured hybrids showed high stability and good magnetic properties. And the magnetic properties of the obtained core/shell structured hybrid could be tuned by the decomposition temperature and time. Therefore, a simple, inexpensive and environment-benign route was proposed to produce magnetism-tunable core/shell structured hybrid in large quantities.

  4. Haem degradation in abnormal haemoglobins.

    PubMed Central

    Brown, S B; Docherty, J C

    1978-01-01

    The coupled oxidation of certain abnormal haemoglobins leads to different bile-pigment isomer distributions from that of normal haemoglobin. The isomer pattern may be correlated with the structure of the abnormal haemoglobin in the neighbourhood of the haem pocket. This is support for haem degradation by an intramolecular reaction. PMID:708385

  5. Synthesis, structure and magnetic behaviour of mixed metal leucophosphite

    SciTech Connect

    Shi Fanian; Moreira dos Santos, Antonio; Cunha-Silva, Luis; Costa, Benilde F.O.; Klinowski, Jacek; Almeida Paz, Filipe A.; Amaral, Vitor S.; Rocha, Joao; Trindade, Tito

    2008-06-15

    A synthetic analogue of leucophosphite, an iron phosphate, was synthesized hydrothermally at 180 deg. C and its chemical composition determined to be {l_brace}K[(FeV)(PO{sub 4}){sub 2}(OH)(H{sub 2}O)].H{sub 2}O{r_brace}. The compound crystallizes in the monoclinic P2{sub 1}/c space group, with a=9.7210(19) A, b=9.6500(19) A, c=12.198(4) A and {beta}=128.569(18){sup o}. While the original all-iron compound is reported to be antiferromagnetic, the inclusion of substitutional vanadium(III) ions renders the structure ferrimagnetic. Diffraction studies and magnetic characterization show that iron and vanadium are disordered throughout the crystallographic sites. The magnetic behaviour of this system was interpreted in terms of a classic ferrimagnetic mean field model, consisting of two antiferromagnetically coupled non-crystallographic 'sublattices'. - Graphical abstract: A new iron(III)-vanadium(III) phosphate, an analogue of leucophosphite, with chemical composition {l_brace}K[(FeV)(PO{sub 4}){sub 2}(OH)(H{sub 2}O)].H{sub 2}O{r_brace}, was isolated using hydrothermal synthesis, and characterized structurally by single-crystal X-ray diffraction, thermogravimetric analysis and vibrational spectroscopy. The magnetic properties of the material show ferrimagnetic features at low temperature.

  6. Magnetic structures in potential multiferroic GdCrO3

    NASA Astrophysics Data System (ADS)

    Manuel, Pascal; Chapon, Laurent; Khalyavin, Dmitry; Xueyun, Wang; Cheong, Sang-Wook

    2015-03-01

    For the past decade, multiferroics materials have atracted a lot of attention in the condensed matter community because of potential applications for devices. A somewhat ambiguous addition to the multiferroics family was recently reported in the peroskite based GdCrO3 in both bulk and thin film samples. Indeed, ferroelectricity was evidenced by a strong enhancement of the capacitance in a field but significant leakage and no well developed P-E hysteresis blurred the picture. Our own measurements clearly indicate the existence of a polar phase below 2K. To complete the understanding of this material, the determination of the magnetic structure is required but is hampered by the fact Gd is a strong neutron absorber. We will present some neutron diffraction data collected on an isotopic 160GdCrO3 sample at the WISH diffractometer at ISIS which confirm the presence of three successive magnetic phases, previously only seen by magnetization, as a function of temperature. We will compare our determined structures against predictions based on group theoretical considerations and experimental work on other rare-earth ortho-chromates and discuss the mechanism for multiferroicity.

  7. Granularity in the magnetic field structure of M83

    NASA Technical Reports Server (NTRS)

    Allen, R. J.; Sukumar, S.

    1990-01-01

    Researchers recently reported Very Large Array (VLA) 20 cm continuum polarization observations of the bright, nearly face-on southern spiral galaxy M83 (NGC 5236) at a spatial resolution of 2 kpc (Sukumar and Allen 1989). The strongest linearly-polarized emission is found in two giant arcs, with typical lengths of about 30 kpc, which are situated roughly opposite each other in the dark outer regions of the galaxy at a radius of 12 kpc from the center. These regions of high polarized intensity (and hence highly-uniform magnetic field) do not coincide with any prominent spiral-arm tracers, in contrast to the expectations of simple models for the large-scale compression of magnetic field in density-wave shock fronts. From a comparison of the data with previous results at 6 cm, the authors concluded that the low polarization in the central regions of the galaxy is a result of disorder in the interstellar magnetic field. The most likely cause of this disorder is the greater star formation activity observed in the inner parts of the galaxy. The intrinsic direction of the magnetic field in the outer parts of the galaxy has also recently been determined on a length scale of 6.5 kpc from a comparison of the VLA 20 cm results with 6.3 cm observations obtained earlier with the Effelsberg telescope (Sukumar et al. 1989). There is very little Faraday rotation in the regions of the highly-polarized arcs of emission. The magnetic field in these polarized arcs is parallel to the general spiral arm structure seen in the usual optical tracers (dust, HII regions) in the bright inner parts of the galaxy disk. The maximum observed polarization at 2 kpc resolution is about 50 percent.

  8. Magnetic quantum well states in ultrathin film and wedge structures

    SciTech Connect

    Li, D.; Bader, S.D.

    1996-04-01

    Magnetic quantum-well (QW) states are probed with angle- and spin-resolved photoemission to address critical issues pertaining to the origin of the giant magnetoresistance (GMR) optimization and oscillatory coupling of magnetic multilayers. Two epitaxial systems are highlighted: Cu/Co(wedge)/Cu(100) and Cr/Fe(100)-whisker. The confinement of Cu sp-QW states by a Co barrier requires a characteristic Co thickness of 2.2 {+-} 0.6 {angstrom}, which is consistent with the interfacial Co thickness reported to optimize the GMR of permalloy-Cu structures. The controversial k-space origin of the 18-{angstrom} long period oscillation in Fe/Cr multilayers is identified by the vector that spans the d-derived lens feature of the Cr Fermi surface, based on the emergence of QW states with 17 {+-} 2 {angstrom} periodicity in this region.

  9. Structural studies in columnar basalts from crystallographic and magnetic fabrics

    NASA Astrophysics Data System (ADS)

    Tiphaine, Boiron; Jérôme, Bascou; Pierre, Camps; Eric, Ferre; Claire, Maurice; Bernard, Guy; Marie-Christine, Gerbe

    2010-05-01

    The purpose of this study is to better characterize the columnar and the associated microstructure development in basalt flows. The thermal contraction (O'Reilly, 1879) is the main hypothesis to explain the columnar formation. However, neither the structures which appear in basalt flow constituted of three levels (Tomkeieff, 1940) nor circular and radial structures within the prisms (for which weathering nor fracturing can account for) can be explained by the thermal contraction theory alone. An early structuring process during solidification (Guy and Le Coze, 1990) could play for a part that must be discussed (Guy, 2010). We studied two recent basalt flows (75 000 years) from the French Massif Central, in which the three flow levels are clearly observed. In the first basalt flow (La Palisse, Ardèche), the emission centre and the flow direction are known. In the second one (Saint Arcons d'Allier, Haute Loire), the prismatic columns are particularly well developed. In order to characterize the flow structure at different scales, from the flow to the grain scale, anisotropy of magnetic susceptibility (AMS) measurements were performed. The AMS data were coupled with crystallographic preferred orientation measurements of magnetite, plagioclase and clinopyroxene using Electron Backscattered Diffraction (EBSD) and image analyses from perpendicular thin sections. Magnetic mineralogy studies of the La Palisse basalts, in particular the thermomagnetic curves, indicate that the main carrier of AMS is high-Ti titanomagnetite (Tc≈130°C). AMS measurements of about a hundred samples show a higher degree of AMS (P parameter) in the middle level in comparison to the base. Inversely, the bulk magnetic susceptibility (Km) is higher at the flow base. Distinctive parameters for the different levels of the basaltic flows could be then provided by AMS measurements.. Moreover, the comparison between AMS and EBSD data indicate that the magnetic susceptibility carried by the magnetic

  10. Magnetic field adjustment structure and method for a tapered wiggler

    SciTech Connect

    Halbach, Klaus

    1988-03-01

    An improved method and structure is disclosed for adjusting the magnetic field generated by a group of electromagnet poles spaced along the path of a charged particle beam to compensate for energy losses in the charged particles which comprises providing more than one winding on at least some of the electromagnet poles; connecting one respective winding on each of several consecutive adjacent electromagnet poles to a first power supply, and the other respective winding on the electromagnet pole to a different power supply in staggered order; and independently adjusting one power supply to independently vary the current in one winding on each electromagnet pole in a group whereby the magnetic field strength of each of a group of electromagnet poles may be changed in smaller increments.

  11. Magnetic field adjustment structure and method for a tapered wiggler

    SciTech Connect

    Halbach, Klaus

    1988-01-01

    An improved method and structure is disclosed for adjusting the magnetic field generated by a group of electromagnet poles spaced along the path of a charged particle beam to compensate for energy losses in the charged particles which comprises providing more than one winding on at least some of the electromagnet poles; connecting one respective winding on each of several consecutive adjacent electromagnet poles to a first power supply, and the other respective winding on the electromagnet pole to a different power supply in staggered order; and independently adjusting one power supply to independently vary the current in one winding on each electromagnet pole in a group whereby the magnetic field strength of each of a group of electromagnet poles may be changed in smaller increments.

  12. Modulating Magnetic Properties by Tailoring In-Plane Domain Structures in Hexagonal YMnO3 Films.

    PubMed

    Deng, Shiqing; Cheng, Shaobo; Liu, Ming; Zhu, Jing

    2016-09-28

    Periodic structures and the coupling of multiorder parameters in complex oxides heterojunctions can generate exotic properties, of interest both for fundamental researches and for device applications. Here, we report a self-assembling in-plane periodic domain structure, and the resulting rich magnetic states, in a h-YMnO3 thin film fabricated on c-face sapphire substrate. Detailed structural investigations at atomic-level reveal the fashion of alternating domains under tensile or compressive strains separated by a boundary region. Tuned by this in-plane domain structure, the abnormal magnetic properties, such as the ferromagnetic enhancement and the unexpected spin glass state (below ∼38 K), are realized. Moreover, the existence of ferroelectric polarization is confirmed by scanning transmission electron microscopy, which brings in the chances of magnetoelectric coupling effect. These results manifest the close connections between the magnetic properties and such in-plane microstructures, suggesting the possibility of tuning the coupling effects via strain engineering in the hexagonal manganite film. PMID:27608731

  13. Abnormal structural luteolysis in ovaries of the senescence accelerated mouse (SAM): expression of Fas ligand/Fas-mediated apoptosis signaling molecules in luteal cells.

    PubMed

    Kiso, Minako; Manabe, Noboru; Komatsu, Kohji; Shimabe, Munetake; Miyamoto, Hajime

    2003-12-01

    Senescence accelerated mouse-prone (SAMP) mice with a shortened life span show accelerated changes in many of the signs of aging and a shorter reproductive life span than SAM-resistant (SAMR) controls. We previously showed that functional regression (progesterone dissimilation) occurs in abnormally accumulated luteal bodies (aaLBs) of SAMP mice, but structural regression of luteal cells in aaLB is inhibited. A deficiency of luteal cell apoptosis causes the abnormal accumulation of LBs in SAMP ovaries. In the present study, to show the abnormality of Fas ligand (FasL)/Fas-mediated apoptosis signal transducing factors in the aaLBs of the SAMP ovaries, we assessed the changes in the expression of FasL, Fas, caspase-8 and caspase-3 mRNAs by reverse transcription-polymerase chain reaction, and in the expression and localization of FasL, Fas and activated caspase-3 proteins by Western blotting and immunohistochemistry, respectively, during the estrus cycle/luteolysis. These mRNAs and proteins were expressed in normal LBs of both SAMP and SAMR ovaries, but not at all or only in trace amounts in aaLBs of SAMP, indicating that structural regression is inhibited by blockage of the expression of these transducing factors in luteal cells of aaLBs in SAMP mice. PMID:14967896

  14. Perovskite LaPbMSbO{sub 6} (M=Co, Ni): Structural distortion, magnetic and dielectric properties

    SciTech Connect

    Bai, Yijia; Han, Lin; Liu, Xiaojuan; Deng, Xiaolong; Wu, Xiaojie; Yao, Chuangang; Liang, Qingshuang; Meng, Junling; Meng, Jian

    2014-09-15

    The B-site ordered double perovskite oxides LaPbMSbO{sub 6} (M=Co, Ni) have been synthesized via the modified Sol–Gel precursor two-step route. Rietveld refinements reveal strong abnormal structural distortion and BO{sub 6} octahedral deformation appearing along the ab plane. Owing to the cooperative Jahn–Teller effect of Co{sup 2+} and Pb{sup 2+} ions, the Co-related compound exhibits almost complete Co{sup 2+}–Sb{sup 5+} order. For magnetic properties, spin-canted antiferromagnetic state with high extent of magnetic frustration is confirmed. The Ni-related compound presents heavier magnetic frustration for introducing tiny disorder on site occupation accompanied with valence state and further enhancing the complexity of magnetic competition. Dielectric measurements present a considerable temperature dependent dielectric relaxation with great dc-like loss feature in the LaPbCoSbO{sub 6}. For LaPbNiSbO{sub 6}, however, the permittivity with low dielectric loss is shown to be insensitive to either temperature or frequency. The corresponding electronic active energy manifests that the weakly bounded 3d-electron is prone to hop in a more distorted Co–Sb sublattice. - Graphical abstract: XRD Rietveld refinement result of LaPbCoSbO{sub 6} presented a large BO{sub 6} octahedral distortion along the ab plane. Based upon the variations from Co–O–Sb bond angles, a fierce competition from many extended magnetic coupling routes (M–O–O–M) would induce a considerably large magnetic frustration and electron hopping restriction. - Highlights: • Highly ordered LaPbMSbO{sub 6} (M=Co, Ni) were synthesized. • Abnormal structural distortion appeared in the ab plane. • Strong magnetic frustration was confirmed via M{sup 2+}–O–O–M{sup 2+} route. • Dielectric measurements presented a large difference between Co and Ni samples. • 3d-electronic structure determines lattice distortion and physical properties.

  15. Cryogenic expansion joint for large superconducting magnet structures

    DOEpatents

    Brown, Robert L.

    1978-01-01

    An expansion joint is provided that accommodates dimensional changes occurring during the cooldown and warm-up of large cryogenic devices such as superconducting magnet coils. Flattened tubes containing a refrigerant such as gaseous nitrogen (N.sub.2) are inserted into expansion spaces in the structure. The gaseous N.sub.2 is circulated under pressure and aids in the cooldown process while providing its primary function of accommodating differential thermal contraction and expansion in the structure. After lower temperatures are reached and the greater part of the contraction has occured, the N.sub.2 liquefies then solidifies to provide a completely rigid structure at the cryogenic operating temperatures of the device.

  16. Specialized probes with nanowhisker structures for high resolution magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Zhukov, M. V.; Belousov, K. I.; Mozharov, A. M.; Mukhin, I. S.; Golubok, A. O.

    2015-11-01

    Creation and study of specialized nanowhisker probes with magnetic coating are performed for high-precision imaging of various objects by means of atomic force and magnetic force microscopy. Thin layers of Ni and Co are deposited on the surface of nanowhisker structures to perform visualization of magnetic fields on the sample surface, in particular, structure of pits on a hard disk drive (HDD). It is revealed that probes with nanowhisker structures covered with magnetic coating due to their high aspect ratio demonstrate a higher spatial resolution and contrast of magnetic fields visualization in comparison with standard magnetic probes.

  17. Microfabricated magnetic structures for future medicine: from sensors to cell actuators

    PubMed Central

    Vitol, Elina A; Novosad, Valentyn; Rozhkova, Elena A

    2013-01-01

    In this review, we discuss the prospective medical application of magnetic carriers microfabricated by top-down techniques. Physical methods allow the fabrication of a variety of magnetic structures with tightly controlled magnetic properties and geometry, which makes them very attractive for a cost-efficient mass-production in the fast growing field of nanomedicine. Stand-alone fabricated particles along with integrated devices combining lithographically defined magnetic structures and synthesized magnetic tags will be considered. Applications of microfabricated multifunctional magnetic structures for future medicinal purposes range from ultrasensitive in vitro diagnostic bioassays, DNA sequencing and microfluidic cell sorting to magnetomechanical actuation, cargo delivery, contrast enhancement and heating therapy. PMID:23148542

  18. Increased reliability of nuclear magnetic resonance protein structures by consensus structure bundles.

    PubMed

    Buchner, Lena; Güntert, Peter

    2015-02-01

    Nuclear magnetic resonance (NMR) structures are represented by bundles of conformers calculated from different randomized initial structures using identical experimental input data. The spread among these conformers indicates the precision of the atomic coordinates. However, there is as yet no reliable measure of structural accuracy, i.e., how close NMR conformers are to the "true" structure. Instead, the precision of structure bundles is widely (mis)interpreted as a measure of structural quality. Attempts to increase precision often overestimate accuracy by tight bundles of high precision but much lower accuracy. To overcome this problem, we introduce a protocol for NMR structure determination with the software package CYANA, which produces, like the traditional method, bundles of conformers in agreement with a common set of conformational restraints but with a realistic precision that is, throughout a variety of proteins and NMR data sets, a much better estimate of structural accuracy than the precision of conventional structure bundles.

  19. A Novel Integrated Structure with a Radial Displacement Sensor and a Permanent Magnet Biased Radial Magnetic Bearing

    PubMed Central

    Sun, Jinji; Zhang, Yin

    2014-01-01

    In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM) to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs. PMID:24469351

  20. A novel integrated structure with a radial displacement sensor and a permanent magnet biased radial magnetic bearing.

    PubMed

    Sun, Jinji; Zhang, Yin

    2014-01-01

    In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM) to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs. PMID:24469351

  1. A novel integrated structure with a radial displacement sensor and a permanent magnet biased radial magnetic bearing.

    PubMed

    Sun, Jinji; Zhang, Yin

    2014-01-24

    In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM) to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs.

  2. Development of three-dimensional printing system for magnetic elastomer with control of magnetic anisotropy in the structure

    NASA Astrophysics Data System (ADS)

    Tsumori, Fujio; Kawanishi, Hidenori; Kudo, Kentaro; Osada, Toshiko; Miura, Hideshi

    2016-06-01

    In this paper, we report on a new system of three-dimensional (3D) printing for a magnetic elastomer that contains magnetic particles. Not only can we fabricate a three-dimensional structure, but we can also control the magnetically anisotropic property of each position in the structure using the present technique. Our new system employed photocurable poly(dimethylsiloxane) (PDMS) as the base material so that a method similar to a conventional 3D printing process with photolithography can be used. A magnetic powder was mixed with photocurable PDMS, and particle chain clusters were obtained by applying a magnetic field during the curing process. These chain clusters provide an anisotropic property in each part of the printed structure. We show some results of preliminary experiments and 3D printed samples in this paper. If the fabricated structure was placed under an applied magnetic field, each chain cluster will cause the rotational moment to be along the magnetic flux line, which can deform a soft matrix body. This deformation can be used as a magnetic actuator for the structure. Variable deformable structures could be developed using the present method.

  3. Constructing the Coronal Magnetic Field by Correlating Parameterized Magnetic Field Lines with Observed Coronal Plasma Structures

    NASA Technical Reports Server (NTRS)

    Allen, Gary G.; Alexander, David

    1999-01-01

    A method is presented for constructing the coronal magnetic field from photospheric magnetograms and observed coronal loops. A set of magnetic field lines generated from magnetogram data is parameterized and then deformed by varying the parameterized values. The coronal flux tubes associated with this field are adjusted until the correlation between the field lines and the observed coronal loops is maximized. A mathematical formulation is described which ensures that (1) the normal component of the photospheric field remains unchanged, (2) the field is given in the entire corona over an active region, (3) the field remains divergence-free, and 4electric currents are introduced into the field. It is demonstrated that a parameterization of a potential field, comprising a radial stretching of the field, can provide a match for a simple bipolar active region, AR 7999, which crossed the central meridian on 1996 November 26. The result is a non-force-free magnetic field with the Lorentz force being of the order of 10(exp -5.5) g per s(exp 2) resulting from an electric current density of 0.79 micro A per m(exp 2). Calculations show that the plasma beta becomes larger than unity at a strong non-radial currents requires low height of about 0.25 solar radii supporting the non-force-free conclusion. The presence of such strong non-radial currents requires large transverse pressure gradients fo maintain a magnetostatic atmosphere, required by the relatively persistent nature of the coronal structures observed in AR 7999. This scheme is an important tool in generating a magnetic field solution consistent with the coronal flux tube observations and the observed photospheric magnetic field.

  4. Magnetic Configurations in Co/Cu Multilayered Nanowires: Evidence of Structural and Magnetic Interplay.

    PubMed

    Reyes, D; Biziere, N; Warot-Fonrose, B; Wade, T; Gatel, C

    2016-02-10

    Off-axis electron holography experiments have been combined with micromagnetic simulations to study the remnant magnetic states of electrodeposited Co/Cu multilayered nanocylinders. Structural and chemical data obtained by transmission electron microscopy have been introduced in the simulations. Three different magnetic configurations such as an antiparallel coupling of the Co layers, coupled vortices, and a monodomain-like state have been quantitatively mapped and simulated. While most of the wires present the same remnant state whatever the direction of the saturation field, we show that some layers can present a change from an antiparallel coupling to vortices. Such a configuration can be of particular interest to design nano-oscillators with two different working frequencies. PMID:26783831

  5. Defect-induced magnetic structure of CuMnSb

    NASA Astrophysics Data System (ADS)

    Máca, F.; Kudrnovský, J.; Drchal, V.; Turek, I.; Stelmakhovych, O.; Beran, P.; Llobet, A.; Marti, X.

    2016-09-01

    The observed ground state for the CuMnSb alloy is the antiferromagnetic (111) phase as confirmed by neutron diffraction experiments. Ab initio total energy calculations for ideal, defect-free CuMnSb contradict this result and indicate that other magnetic structures can have their total energies lower. It is known that Heusler alloys usually contain various defects depending on the sample preparation. We have therefore investigated magnetic phases of CuMnSb assuming the most common defects which exist in real experimental conditions. The full-potential supercell approach and a Heisenberg model approach using the coherent potential approximation are adopted. The results of the total energy supercell calculations indicate that defects that bring Mn atoms close together promote the antiferromagnetic (111) structure already for a low critical defect concentrations (≈3 %). A detailed study of exchange interactions between Mn moments further supports the above stabilization mechanism. Finally, the stability of the antiferromagnetic (111) order is enhanced by inclusion of electron correlations in narrow Mn bands. The present refinement structure analysis of the neutron scattering experiment supports theoretical conclusions.

  6. Synthesis, structure, and magnetic characterization of Cr4US8

    NASA Astrophysics Data System (ADS)

    Ward, Matthew D.; Chan, Ian Y.; Malliakas, Christos D.; Lee, Minseong; Choi, Eun Sang; Ibers, James A.

    2016-01-01

    The compound Cr4US8 has been synthesized at 1073 K and its crystal structure has been determined at 100 K. The structure is modulated with a two-fold commensurate supercell. The subcell may be indexed in an orthorhombic cell but weak supercell reflections lead to the monoclinic superspace group P21/c(α0γ)0s with two Cr sites, one U site, and four S sites. The structure comprises a three-dimensional framework of CrS6 octahedra with channels that are partially occupied by U atoms. Each U atom in these channels is coordinated by eight S atoms in a bicapped trigonal-prismatic arrangement. The magnetic behavior of Cr4US8 is complex. At temperatures above ~120 K at all measured fields, there is little difference between field-cooled and zero field-cooled data and χ(T) decreases monotonously with temperature, which is reminiscent of the Curie-Weiss law. At lower temperatures, the temperature dependence of χ(T) is complex and strongly dependent on the magnetic field strength.

  7. Low resistance magnetic tunnel junctions and their interface structures

    SciTech Connect

    Fujikata, J.; Ishi, T.; Mori, S.; Matsuda, K.; Mori, K.; Yokota, H.; Hayashi, K.; Nakada, M.; Kamijo, A.; Ohashi, K.

    2001-06-01

    Effects of interface structure and oxidation state were studied in stacked magnetic tunnel junction (MTJ) structures with top and bottom antiferromagnetic layers to obtain optimum resistance and high tunneling magnetoresistance (TMR) ratios for read heads. The roughness of the NiFe surface and the Al coverage were significantly improved by introduction of O{sub 2} surfactant gas on the Ta-seed-layer surface, which increased TMR ratios of the MTJ with low resistance area (RA) products of less than 10 {Omega}{mu}m2. Furthermore, it was found that avoidance of Ni oxidation and Co oxidation at the tunnel barrier interface is essential to obtaining high TMR ratios, and that a good Al coverage and Fe{endash}oxide formation may enhance TMR ratios when Fe-rich magnetic materials are used. For the top-type and bottom-type structures, a TMR ratio of 12%{endash}17% with RA products of 6{endash}7 {Omega}{mu}m2 was obtained, which provides sufficient performance for read heads. {copyright} 2001 American Institute of Physics.

  8. Magnetic field-dependent spin structures of nanocrystalline holmium

    PubMed Central

    Szary, Philipp; Kaiser, Daniel; Bick, Jens-Peter; Lott, Dieter; Heinemann, André; Dewhurst, Charles; Birringer, Rainer; Michels, Andreas

    2016-01-01

    The results are reported of magnetic field-dependent neutron diffraction experiments on polycrystalline inert-gas condensed holmium with a nanometre crystallite size (D = 33 nm). At T = 50 K, no evidence is found for the existence of helifan(3/2) or helifan(2) structures for the nanocrystalline sample, in contrast with results reported in the literature for the single crystal. Instead, when the applied field H is increased, the helix pattern transforms progressively, most likely into a fan structure. It is the component of H which acts on the basal-plane spins of a given nanocrystallite that drives the disappearance of the helix; for nanocrystalline Ho, this field is about 1.3 T, and it is related to a characteristic kink in the virgin magnetization curve. For a coarse-grained Ho sample, concomitant with the destruction of the helix phase, the emergence of an unusual angular anisotropy (streak pattern) and the appearance of novel spin structures are observed. PMID:27047307

  9. Structural and magnetic properties of chromium doped zinc ferrite

    SciTech Connect

    Sebastian, Rintu Mary; Thankachan, Smitha; Xavier, Sheena; Mohammed, E. M.; Joseph, Shaji

    2014-01-28

    Zinc chromium ferrites with chemical formula ZnCr{sub x}Fe{sub 2−x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by Sol - Gel technique. The structural as well as magnetic properties of the synthesized samples have been studied and reported here. The structural characterizations of the samples were analyzed by using X – Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). The single phase spinel cubic structure of all the prepared samples was tested by XRD and FTIR. The particle size was observed to decrease from 18.636 nm to 6.125 nm by chromium doping and induced a tensile strain in all the zinc chromium mixed ferrites. The magnetic properties of few samples (x = 0.0, 0.4, 1.0) were investigated using Vibrating Sample Magnetometer (VSM)

  10. Structural, magnetic and optical properties of two concomitant molecular crystals

    NASA Astrophysics Data System (ADS)

    Silva, Manuela Ramos; Milne, Bruce; Coutinho, Joana T.; Pereira, Laura C. J.; Martín-Ramos, Pablo; Pereira da Silva, Pedro S.; Martín-Gil, Jesús

    2016-03-01

    A new 1D complex has been prepared and characterized. X-ray single crystal structure confirms that the Cu(II) ions assemble in alternating chains with Cu … Cu distances of 2.5685(4) and 3.1760(4) Å. The temperature dependence of the magnetic susceptibility reveals an antiferromagnetic interaction between the paddle-wheel copper centers with an exchange of -300 cm-1. The exchange integral was also determined by quantum chemical ab-initio calculations, using polarised and unpolarised basis sets reproducing well the experimental value. The second harmonic generation efficiency of a concomitantly crystallized material was evaluated and was found to be comparable to urea.

  11. On boundaries among magnetic structures at the sun

    NASA Astrophysics Data System (ADS)

    Ishkov, V. N.; Linke, J.

    1990-10-01

    Results of an analysis of published observational data on large complex active regions (CARs) on the sun are briefly discussed. Boundaries detected in the lower region of the solar atmosphere are shown to reveal the separation of independently developing magnetic structures, which may interact to produce eruption effects such as flares, reconnection, and flux-tube cancelling, as proposed by Linke and Bachmann (1989). The characteristics of these boundaries are illustrated with diagrams based on CAR data for June-July 1982, July-August 1983, and October 1979.

  12. An Investigation of Magnetic, Electronic and Structural Properties of Metallofullerenes

    NASA Astrophysics Data System (ADS)

    Ong, S. Vincent; Qian, Meichun; Khanna, Shiv

    2008-03-01

    Gadolinium based endohedral metallofullerenes Gd3N@C80 functionalized with OH radicals have been found to enhance the relaxivity by orders of magnitude over conventional agents and are being sought as new contrast agents in magnetic resonance imaging (MRI). Using state of the art density functional theory (DFT) in the regime of the local density approximation with the on-site Coulomb interaction (LSDA+U), we have carried out theoretical studies to determine the electronic and magnetic properties of gadolinium-based and lutetium-based nitride fullerenes, namely Lu3-xGdxN@C80 (x = 1-2). While Gd3N@C80 has previously shown promising features as a contrast agent, the idea of replacing gadolinium atoms by lutetium has been proposed to result in a mixed-metal species for multi-modal imaging. Our results indicate that Lu2GdN@C80 is the most stable of all possible configurations with a binding energy 16.57 eV, can be considered for use as both an MRI contrast agent, due to gadolinium's high magnetic moment, and as a potential radioactive therapeutic or diagnostic agent, by neutron activation of a lutetium radioisotope. These results along with details of electronic structure will be presented.

  13. The magnetic structure of EuCu2Sb2

    DOE PAGES

    Ryan, D. H.; Cadogan, J. M.; Anand, V. K.; Johnston, D. C.; Flacau, R.

    2015-05-06

    Antiferromagnetic ordering of EuCu2Sb2 which forms in the tetragonal CaBe2Ge2-type structure (space group P4/nmm #129) has been studied using neutron powder diffraction and 151Eu Mössbauer spectroscopy. The room temperature 151Eu isomer shift of –12.8(1) mm/s shows the Eu to be divalent, while the 151Eu hyperfine magnetic field (Bhf) reaches 28.7(2) T at 2.1 K, indicating a full Eu2+ magnetic moment. Bhf(T) follows a smoothmore » $$S=\\frac{7}{2}$$ Brillouin function and yields an ordering temperature of 5.1(1) K. Refinement of the neutron diffraction data reveals a collinear A-type antiferromagnetic arrangement with the Eu moments perpendicular to the tetragonal c-axis. As a result, the refined Eu magnetic moment at 0.4 K is 7.08(15) μB which is the full free-ion moment expected for the Eu2+ ion with $$S=\\frac{7}{2}$$ and a spectroscopic splitting factor of g = 2.« less

  14. Magnetic and structural properties of ferrihydrite/hematite nanocomposites

    NASA Astrophysics Data System (ADS)

    Pariona, N.; Camacho-Aguilar, K. I.; Ramos-González, R.; Martinez, Arturo I.; Herrera-Trejo, M.; Baggio-Saitovitch, E.

    2016-05-01

    A rich variety of ferrihydrite/hematite nanocomposites (NCs) with specific size, composition and properties were obtained in transformation reactions of 2-line ferrihydrite. Transmission electron microscopy (TEM) observations showed that the NCs consist of clusters of strongly aggregated nanoparticles (NPs) similarly to a "plum pudding", where hematite NPs "raisins" are surrounded by ferrihydrite "pudding". Magnetic measurements of the NCs correlate very well with TEM results; i.e., higher coercive fields correspond to greater hematite crystallite size. First order reversal curve (FORC) measurements were used for the characterization of the magnetic components of the NCs. FORC diagrams revealed that the NCs prepared at short times are composed by single domains with low coercivity, and NCs prepared at times larger than 60 min exhibited elongated distribution along the Hc axis. It suggested that these samples consist of mixtures of different kinds of hematite particles, ones with low coercivity and others with coercivity greater than 600 Oe. For NCs prepared at times larger than 60 min, Mossbauer spectroscopy revealed the presence of two sextets, which one was assigned to fine hematite particles and other to hematite particles with hyperfine parameters near to bulk hematite. The correlation of the structural and magnetic properties of the ferrihydrite/hematite NCs revealed important characteristics of these materials which have not been reported elsewhere.

  15. Imaging solar coronal magnetic structures in 3D

    NASA Astrophysics Data System (ADS)

    Cartledge, N. P.

    The study of solar coronal structures and, in particular prominences, is a key part of understanding the highly complex physical mechanisms occurring in the Sun's atmosphere. Solar prominences are important in their own right and some of the most puzzling questions in solar theory have arisen through their study. For example, how do they form and how is their mass continuously replenished? How can the magnetic field provide their continuous support against gravity over time periods of several months? How can such cool, dense material exist in thermal equilibrium in the surrounding coronal environment? Why do they erupt? A study of their structure and that of the surrounding medium is important in determining the nature of the coronal plasma and magnetic field. Also, prominences are closely associated with other key phenomena such as coronal mass ejections and eruptive solar flares which occur as a prominence loses equilibrium and rises from the solar surface. Our current understanding of these fascinating structures is extremely limited and we know very little about their basic global structure. In fact, recent prominence observations have caused our basic paradigms to be challenged (Priest, 1996) and so we must set up new models in order to gain even a fundamental understanding. Prominences are highly nonlinear, three-dimensional structures. Large feet (or barbs) reach out from the main body of a prominence and reach down to the photosphere where the dense material continuously drains away. These provide a real clue to the three-dimensional nature of the coronal field and its relation to the photospheric field. It is important, therefore, to make stereographic observations of prominences in order to gain a basic understanding of their essentially three-dimensional nature and attempt to formulate new paradigms for their structure and evolution. There is no doubt that the study of prominences in three dimensions is a crucial exercise if we are to develop a better

  16. Octupolar out-of-plane magnetic field structure generation during collisionless magnetic reconnection in a stressed X-point collapse

    SciTech Connect

    Graf von der Pahlen, J.; Tsiklauri, D.

    2014-06-15

    The out-of-plane magnetic field, generated by fast magnetic reconnection, during collisionless, stressed X-point collapse, was studied with a kinetic, 2.5D, fully electromagnetic, relativistic particle-in-cell numerical code, using both closed (flux conserving) and open boundary conditions on a square grid. It was discovered that the well known quadrupolar structure in the out-of-plane magnetic field gains four additional regions of opposite magnetic polarity, emerging near the corners of the simulation box, moving towards the X-point. The emerging, outer, magnetic field structure has opposite polarity to the inner quadrupolar structure, leading to an overall octupolar structure. Using Ampere's law and integrating electron and ion currents, defined at grid cells, over the simulation domain, contributions to the out-of-plane magnetic field from electron and ion currents were determined. The emerging regions of opposite magnetic polarity were shown to be the result of ion currents. Magnetic octupolar structure is found to be a signature of X-point collapse, rather than tearing mode, and factors relating to potential discoveries in experimental scenarios or space-craft observations are discussed.

  17. Developmental Abnormalities of Neuronal Structure and Function in Prenatal Mice Lacking the Prader-Willi Syndrome Gene Necdin

    PubMed Central

    Pagliardini, Silvia; Ren, Jun; Wevrick, Rachel; Greer, John J.

    2005-01-01

    Necdin (Ndn) is one of a cluster of genes deleted in the neurodevelopmental disorder Prader-Willi syndrome (PWS). Ndntm2Stw mutant mice die shortly after birth because of abnormal respiratory rhythmogenesis generated by a key medullary nucleus, the pre-Bötzinger complex (preBötC). Here, we address two fundamental issues relevant to its pathogenesis. First, we performed a detailed anatomical study of the developing medulla to determine whether there were defects within the preBötC or synaptic inputs that regulate respiratory rhythmogenesis. Second, in vitro studies determined if the unstable respiratory rhythm in Ndntm2Stw mice could be normalized by neuromodulators. Anatomical defects in Ndntm2Stw mice included defasciculation and irregular projections of axonal tracts, aberrant neuronal migration, and a major defect in the cytoarchitecture of the cuneate/gracile nuclei, including dystrophic axons. Exogenous application of neuromodulators alleviated the long periods of slow respiratory rhythms and apnea, but some instability of rhythmogenesis persisted. We conclude that deficiencies in the neuromodulatory drive necessary for preBötC function contribute to respiratory dysfunction of Ndntm2Stw mice. These abnormalities are part of a more widespread deficit in neuronal migration and the extension, arborization, and fasciculation of axons during early stages of central nervous system development that may account for respiratory, sensory, motor, and behavioral problems associated with PWS. PMID:15972963

  18. Physics of small metal clusters: Topology, magnetism, and electronic structure

    NASA Astrophysics Data System (ADS)

    Rao, B. K.; Jena, P.

    1985-08-01

    The electronic structure of small clusters of lithium atoms has been calculated using the self-consistent-field, molecular-orbital method. The exchange interaction is treated at the unrestricted Hartree-Fock level whereas the correlation is treated perturbatively up to second order by including pair excitations. This is done in two steps, one involving only the valence electrons and the other including all the electrons. A configuration-interaction calculation has also been done with all possible pair excitations. The equilibrium geometries of both the neutral and ionized clusters have been obtained by starting from random configurations and using the Hellmann-Feynman forces to follow the path of steepest descent to a minimum of the energy surface. The clusters of Li atoms each containing one to five atoms are found to be planar. The equilibrium geometry of a cluster is found to be intimately related to its electronic structure. The preferred spin configuration of a cluster has been found by minimizing the total energy of the cluster with respect to various spin assignments. The planar clusters are found to be less magnetic than expected by Hund's-rule coupling. For three-dimensional clusters, however, the magnetism is governed by Hund's rule. The effect of correlation has been found to have decisive influence on the equilibrium topology and magnetism of the clusters. The binding energy per atom, the energy of dissociation, and the ionization potential of the clusters are compared with experiment and with previous calculations. The physical origin of the magic numbers and the effect of the basis functions on the calculated properties have also been investigated.

  19. Origin of weak magnetism in compounds with cubic laves structure.

    PubMed

    Torun, E; Janner, A; de Groot, R A

    2016-02-17

    The origin of the weak itinerant magnetism in materials such as TiBe2 and ZrZn2 is investigated. The huge peak in the density of states at the Fermi energy is attributed to a special symmetry of the C15 structure: no crystal field splitting of the d levels occurs in the case of coordination by spherical ligands. Crystal field splitting is also investigated for the f orbitals in C15 structures such as PuZn2 and ThMg2. It is observed that the situation in f levels is more complicated than the d levels because the characteristics of the crystal field splitting for f levels does not only depend on the the local point symmetry of the compounds.

  20. Magnetic structure and magnetic transport properties of graphene nanoribbons with sawtooth zigzag edges.

    PubMed

    Wang, D; Zhang, Z; Zhu, Z; Liang, B

    2014-01-01

    The magnetic structure and magnetic transport properties of hydrogen-passivated sawtooth zigzag-edge graphene nanoribbons (STGNRs) are investigated theoretically. It is found that all-sized ground-state STGNRs are ferromagnetic and always feature magnetic semiconductor properties, whose spin splitting energy gap E(g) changes periodically with the width of STGNRs. More importantly, for the STGNR based device, the dual spin-filtering effect with the perfect (100%) spin polarization and high-performance dual spin diode effect with a rectification ratio about 10(10) can be predicted. Particularly, a highly effective spin-valve device is likely to be realized, which displays a giant magnetoresistace (MR) approaching 10(10)%, which is three orders magnitude higher than the value predicted based on the zigzag graphene nanoribbons and six orders magnitude higher than previously reported experimental values for the MgO tunnel junction. Our findings suggest that STGNRs might hold a significant promise for developing spintronic devices. PMID:25533701

  1. Magnetization reversal studies in structurally tailored cobalt nanowires

    NASA Astrophysics Data System (ADS)

    Kaur, Daljit; Chaudhary, Sujeet; Pandya, Dinesh K.; Gupta, Rekha; Kotnala, R. K.

    2013-10-01

    Cobalt nanowires (NWs) having hcp crystal structure are structurally tailored for different preferred orientations (PO) of (0002), (101¯0), (112¯0) and (101¯1) by varying bath temperature and bath concentration in commercially available 50 nm pore diameter polycarbonate (PCT) and 20 nm pore diameter anodic alumina (AAO) membranes. The magnetization studies show orientation dependent competition of magneto-crystalline anisotropy with shape anisotropy. The large effective anisotropy, Keff (along longitudinal direction) of 1.42×106 erg/cc is observed in (0002) PO NWs, which changes sign (-1.50×106 erg/cc) in (101¯0) PO NWs. The angular dependence of coercivity [HC(θ)] in (0002) oriented Co NWs exhibits a non-monotonic behavior in both the 50 nm and 20 nm samples. The fitting of HC(θ) data reveals that the magnetization reversal mechanism initially takes place by curling and subsequently changes to coherent rotation mode after a certain transition angle, which is higher in case of denser NW array. This increase in transition angle can be attributed to the increased magneto-static interactions in the AAO membrane array having 103 times higher NW areal-density than that in PCT membrane array. Role of dipolar/ magnetostatic anisotropy studied by varying NW areal-density and NW diameter.

  2. Analytical solution of thermal magnetization on memory stabilizer structures

    NASA Astrophysics Data System (ADS)

    Tomita, Yu; Viteri, C. Ricardo; Brown, Kenneth R.

    2010-10-01

    We return to the question of how the choice of stabilizer generators affects the preservation of information on structures whose degenerate ground state encodes a classical redundancy code. Controlled-not gates are used to transform the stabilizer Hamiltonian into a Hamiltonian consisting of uncoupled single spins and/or pairs of spins. This transformation allows us to obtain an analytical partition function and derive closed-form equations for the relative magnetization and susceptibility. These equations are in agreement with the numerical results presented in Viteri [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.042313 80, 042313 (2009)] for finite size systems. Analytical solutions show that there is no finite critical temperature, Tc=0, for all of the memory structures in the thermodynamic limit. This is in contrast to the previously predicted finite critical temperatures based on extrapolation. The mismatch is a result of the infinite system being a poor approximation even for astronomically large finite-size systems, where spontaneous magnetization still arises below an apparent finite critical temperature. We extend our analysis to the canonical stabilizer Hamiltonian. Interestingly, Hamiltonians with two-body interactions have a higher apparent critical temperature than the many-body Hamiltonian.

  3. Role of nonlinear localized structures and turbulence in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Pathak, Neha; Yadav, Nitin; Uma, R.; Sharma, R. P.

    2016-09-01

    In the present study, we have analyzed the field localization of kinetic Alfvén wave (KAW) due to the presence of background density perturbation, which are assumed to be originated by the three dimensionally propagating low frequency KAW. These localized structures play an important role for energy transportation at smaller scales in the dispersion range of magnetic power spectrum. For the present model, governing dynamic equations of high frequency pump KAW and low frequency KAW has been derived by considering ponderomotive nonlinearity. Further, these coupled equations have been numerically solved to analyze the resulting localized structures of pump KAW and magnetic power spectrum in the magnetopause regime. Numerically calculated spectrum exhibits inertial range having spectral index of -3/2 followed by steeper scaling; this steepening in the turbulent spectrum is a signature of energy transportation from larger to smaller scales. In this way, the proposed mechanism, which is based on nonlinear wave-wave interaction, may be useful for understanding the particle acceleration and turbulence in magnetopause.

  4. RESOLVING THE INTERNAL MAGNETIC STRUCTURE OF THE SOLAR NETWORK

    SciTech Connect

    Martinez Gonzalez, M. J.; Martinez Pillet, V.; Solanki, S. K.; Barthol, P.; Schmidt, W.

    2012-10-20

    We analyze the spectral asymmetry of Stokes V (circularly polarized) profiles of an individual network patch in the quiet Sun observed by Sunrise/IMaX. At a spatial resolution of 0.''15-0.''18, the network elements contain substructure which is revealed by the spatial distribution of Stokes V asymmetries. The area asymmetry between the red and blue lobes of Stokes V increases from nearly zero at the core of the structure to values close to unity at its edges (single-lobed profiles). Such a distribution of the area asymmetry is consistent with magnetic fields expanding with height, i.e., an expanding magnetic canopy (which is required to fulfill pressure balance and flux conservation in the solar atmosphere). Inversion of the Stokes I and V profiles of the patch confirms this picture, revealing a decreasing field strength and increasing height of the canopy base from the core to the periphery of the network patch. However, the non-roundish shape of the structure and the presence of negative area and amplitude asymmetries reveal that the scenario is more complex than a canonical flux tube expanding with height surrounded by downflows.

  5. Analytical solution of thermal magnetization on memory stabilizer structures

    SciTech Connect

    Tomita, Yu; Viteri, C. Ricardo; Brown, Kenneth R.

    2010-10-15

    We return to the question of how the choice of stabilizer generators affects the preservation of information on structures whose degenerate ground state encodes a classical redundancy code. Controlled-not gates are used to transform the stabilizer Hamiltonian into a Hamiltonian consisting of uncoupled single spins and/or pairs of spins. This transformation allows us to obtain an analytical partition function and derive closed-form equations for the relative magnetization and susceptibility. These equations are in agreement with the numerical results presented in Viteri et al. [Phys. Rev. A 80, 042313 (2009)] for finite size systems. Analytical solutions show that there is no finite critical temperature, T{sub c}=0, for all of the memory structures in the thermodynamic limit. This is in contrast to the previously predicted finite critical temperatures based on extrapolation. The mismatch is a result of the infinite system being a poor approximation even for astronomically large finite-size systems, where spontaneous magnetization still arises below an apparent finite critical temperature. We extend our analysis to the canonical stabilizer Hamiltonian. Interestingly, Hamiltonians with two-body interactions have a higher apparent critical temperature than the many-body Hamiltonian.

  6. Magnetic field structure and halo in NGC 4631

    NASA Astrophysics Data System (ADS)

    Mora, Silvia Carolina; Krause, Marita

    2013-12-01

    seem to be higher than the value in the disk. Conclusions: The derived distribution of rotation measures implies that NGC 4631 has a large-scale regular magnetic field configuration. Despite the strong Faraday depolarization along the galactic plane and the strong beam depolarization in the transition zone between the disk and halo, our research strongly indicates that the magnetic field orientation along the central 5-7 kpc of the disk is also plane-parallel. Therefore, we claim that NGC 4631 also has a magnetic field structure plane-parallel along its entire disk, similar to all other edge-on galaxies observed up to now. Based on observations with the 100 m telescope of the MPIfR (Max-Planck-Institut für Radioastronomie) at Effelsberg and the VLA operated by the NRAO. The NRAO is a facility of the National Science Foundation operated under agreement by Associated Universities, Inc.

  7. Incommensurate Magnetic Structure in the Cubic Noncentrosymmetric Ternary Compound Pr5Ru3Al2

    NASA Astrophysics Data System (ADS)

    Makino, Koya; Okuyama, Daisuke; Avdeev, Maxim; Sato, Taku J.

    2016-07-01

    Magnetic susceptibility and neutron powder diffraction experiments have been performed on the noncentrosymmetric ternary compound Pr5Ru3Al2. The previously reported ferromagnetic transition at 24 K was not detected in our improved-quality samples. Instead, magnetic ordering was observed in the DC magnetic susceptibility at T{c} ≃ 3.8 K. The neutron powder diffraction experiment further indicates that an incommensurate magnetic structure is established below Tc with the magnetic modulation vector {{q}} ≃ (0.066,0.066,0.066) (r.l.u.). A candidate for the magnetic structure is proposed using representation analysis.

  8. Structural and magnetic stability of Fe{sub 2}NiSi

    SciTech Connect

    Gupta, Dinesh C. Bhat, Idris Hamid Chauhan, Mamta

    2014-04-24

    Full-potential ab-initio calculations in the stable F-43m phase have been performed to investigate the structural and magnetic properties of Fe{sub 2}NiSi inverse Heusler alloys. The spin magnetic moment distributions show that present material is ferromagnetic in stable F-43m phase. Further, spin resolved electronic structure calculations show that the discrepancy in magnetic moments of Fe-I and Fe-II depend upon the hybridization of Fe with the main group element. It is found that the main group electron concentration is predominantly responsible in establishing the magnetic properties, formation of magnetic moments and the magnetic order for present alloy.

  9. Electronic structure, magnetic and structural properties of Ni doped ZnO nanoparticles

    SciTech Connect

    Kumar, Shalendra; Vats, Prashant; Gautam, S.; Gupta, V.P.; Verma, K.D.; Chae, K.H.; Hashim, Mohd; Choi, H.K.

    2014-11-15

    Highlights: • XRD, and HR-TEM results show the single phase nature of Ni doped ZnO nanoparticles. • dc magnetization results indicate the RT-FM in Ni doped ZnO nanoparticles. • Ni L{sub 3,2} edge NEXAFS spectra infer that Ni ions are in +2 valence state. • O K edge NEXAFS spectra show that O vacancy increases with Ni doping in ZnO. - Abstract: We report structural, magnetic and electronic structural properties of Ni doped ZnO nanoparticles prepared by auto-combustion method. The prepared nanoparticles were characterized by using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and dc magnetization measurements. The XRD and HR-TEM results indicate that Ni doped ZnO nanoparticles have single phase nature with wurtzite lattice and exclude the presence of secondary phase. NEXAFS measurements performed at Ni L{sub 3,2}-edges indicates that Ni ions are in +2 valence state and exclude the presence of Ni metal clusters. O K-edge NEXAFS spectra indicate an increase in oxygen vacancies with Ni-doping, while Zn L{sub 3,2}-edge show the absence of Zn-vacancies. The magnetization measurements performed at room temperature shows that pure and Ni doped ZnO exhibits ferromagnetic behavior.

  10. Structural safety assessment under the low temperature of KSTAR superconducting magnet-supporting post

    NASA Astrophysics Data System (ADS)

    Her, N. I.; Sa, J. W.; Cho, S.; Do, C. J.; Choi, C. H.; Kim, B. C.; Im, K. H.; Kyum, M.; Kim, W. C.; Kim, G. H.; Yoo, B. J.; Oh, Y. K.; Kim, D. L.; Kwon, M.; Lee, G. S.; Kstar Team

    2001-01-01

    A magnet-supporting post installed between the lower TF coil cooled by 4.5 K supercritical helium and the cryostat base is one of the most important components of the superconducting magnet-supporting structure for KSTAR Tokamak. This structure should be flexible to absorb thermal shrink of the magnet and should also be rigid to support the magnet weight and the plasma disruption load. The post was designed with stainless steel (SS) 316 LN and carbon fiber reinforced plastic (CFRP) that has low thermal conductivity and high structural strength at low temperature. In order to verify the fabricability and the structural safety, a whole scale prototype of the KSTAR magnet-supporting post was manufactured and tested. Both static and compressive cyclic load tests under the maximum plasma vertical disruption load and the magnet dead weight were performed. The test results showed that the magnet-supporting post of KSTAR Tokamak was fabricable and structurally rigid.

  11. Chromosomal abnormalities in human sperm

    SciTech Connect

    Martin, R.H.

    1985-01-01

    The ability to analyze human sperm chromosome complements after penetration of zona pellucida-free hamster eggs provides the first opportunity to study the frequency and type of chromosomal abnormalities in human gametes. Two large-scale studies have provided information on normal men. We have studied 1,426 sperm complements from 45 normal men and found an abnormality rate of 8.9%. Brandriff et al. (5) found 8.1% abnormal complements in 909 sperm from 4 men. The distribution of numerical and structural abnormalities was markedly dissimilar in the 2 studies. The frequency of aneuploidy was 5% in our sample and only 1.6% in Brandriff's, perhaps reflecting individual variability among donors. The frequency of 24,YY sperm was low: 0/1,426 and 1/909. This suggests that the estimates of nondisjunction based on fluorescent Y body data (1% to 5%) are not accurate. We have also studied men at increased risk of sperm chromosomal abnormalities. The frequency of chromosomally unbalanced sperm in 6 men heterozygous for structural abnormalities varied dramatically: 77% for t11;22, 32% for t6;14, 19% for t5;18, 13% for t14;21, and 0% for inv 3 and 7. We have also studied 13 cancer patients before and after radiotherapy and demonstrated a significant dose-dependent increase of sperm chromosome abnormalities (numerical and structural) 36 months after radiation treatment.

  12. Structural, magnetic and electronic structure properties of Co doped ZnO nanoparticles

    SciTech Connect

    Kumar, Shalendra; Song, T.K.; Gautam, Sanjeev; Chae, K.H.; Kim, S.S.; Jang, K.W.

    2015-06-15

    Highlights: • XRD and HR-TEM results show the single phase nature of Co doped ZnO nanoparticles. • XMCD and dc magnetization results indicate the RT-FM in Co doped ZnO nanoparticles. • Co L{sub 3,2} NEXAFS spectra infer that Co ions are in 2+ valence state. • O K edge NEXAFS spectra show that O vacancy increases with Co doping in ZnO. - Abstract: We reported structural, magnetic and electronic structure studies of Co doped ZnO nanoparticles. Doping of Co ions in ZnO host matrix has been studied and confirmed using various methods; such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersed X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, magnetic hysteresis loop measurements and X-ray magnetic circular dichroism (XMCD). From the XRD and HR-TEM results, it is observed that Co doped ZnO nanoparticles have single phase nature with wurtzite structure and exclude the possibility of secondary phase formation. FE-SEM and TEM micrographs show that pure and Co doped nanoparticles are nearly spherical in shape. O K edge NEXAFS spectra indicate that O vacancies increase with Co doping. The Co L{sub 3,2} edge NEXAFS spectra revealed that Co ions are in 2+ valence state. DC magnetization hysteresis loops and XMCD results clearly showed the intrinsic origin of temperature ferromagnetism in Co doped ZnO nanoparticles.

  13. Small-molecule Structure Correctors Target Abnormal Protein Structure and Function: The Structure Corrector Rescue of Apolipoprotein E4–associated Neuropathology

    PubMed Central

    Mahley, Robert W.; Huang, Yadong

    2013-01-01

    An attractive strategy to treat proteinopathies—diseases caused by malformed or misfolded proteins—is to restore protein function by inducing proper three-dimensional structure. We hypothesized that this approach would be effective in reversing the detrimental effects of apolipoprotein (apo) E4, the major allele that significantly increases the risk of developing Alzheimer’s disease and other neurodegenerative disorders. ApoE4’s detrimental effects result from its altered protein conformation (“domain interaction”), making it highly susceptible to proteolytic cleavage and the generation of neurotoxic fragments. Here, we review apoE structure and function, how apoE4 causes neurotoxicity, and describe the identification of potent small-molecule-based “structure correctors” that induce proper apoE4 folding. SAR studies identified a series of small molecules that significantly reduced apoE4’s neurotoxic effects in cultured neurons, and a series that reduced apoE4 fragment levels in vivo, providing proof-of-concept for our approach. Structure corrector–based therapies could prove highly effective for the treatment of many protein-misfolding diseases. PMID:23013167

  14. A co-crystal of polyoxometalates exhibiting single-molecule magnet behavior: the structural origin of a large magnetic anisotropy

    SciTech Connect

    Fang, Xikui; McCallum, Kendall; Pratt III, Harry D.; Anderson, Travis M.; Dennis, Kevin; Luban, Marshall

    2012-03-29

    A polyoxometalate-based {MnIII3MnIV} single-molecule magnet exhibits a large axial anisotropy (D = −0.86 cm−1) resulting from a near-parallel alignment of Jahn–Teller axes. Its rigorous three-fold symmetry (i.e. rhombicity E → 0) and increased intercluster separation via co-crystallization effectively hamper quantum tunnelling of the magnetization. Graphical abstract: A co-crystal of polyoxometalates exhibiting single-molecule magnet behavior: the structural origin of a large magnetic anisotropy

  15. Structure, magnetic order and excitations in the 245 family of Fe-based superconductors.

    PubMed

    Bao, Wei

    2015-01-21

    Elastic neutron scattering simultaneously probes both the crystal structure and magnetic order in a material. Inelastic neutron scattering measures phonons and magnetic excitations. Here, we review the average composition, crystal structure and magnetic order in the 245 family of Fe-based superconductors and in related insulating compounds from neutron diffraction works. A three-dimensional phase-diagram summarizes various structural, magnetic and electronic properties as a function of the sample composition. A high pressure phase diagram for the superconductor is also provided. Magnetic excitations and the theoretic Heisenberg Hamiltonian are provided for the superconductor. Issues for future works are discussed. PMID:25427222

  16. Structure and magnetism of epitaxial rare-earth-transition-metal films

    SciTech Connect

    Fullerton, E.E.; Sowers, C.H.; Pearson, J.P.; Bader, S.D.

    1996-10-01

    Growth of epitaxial transition-metal superlattices; has proven essential in elucidating the role of crystal orientation and structure on magnetic properties such as giant magnetoresistance, interlayer coupling, and magnetic surface anisotropies. Extending these studies to the growth of epitaxial rare earth-transition metal (RE-TM) films and superlattices promises to play an equally important role in exploring and optimizing the properties of hard magnets. For instance, Skomski and Coey predict that a giant energy product (120 MG Oe) is possible in multilayer structures consisting of aligned hard-magnet layers exchanged coupled with soft-phase layers with high magnetization. Epitaxy provides one route to synthesizing such exchange-hardened magnets on controlled length scales. Epitaxial growth also allows the magnetic properties to be tailored by controlling the crystal orientation and the anisotropies of the magnetic layers and holds the possibility of stabilizing metastable phases. This paper describes the epitaxy and magnetic properties for several alloys.

  17. Structure and magnetic properties of epitaxial terbium- iron thin films

    NASA Astrophysics Data System (ADS)

    Wang, Chuei-Tang

    TbFe2 is a giant magnetostrictive material which has the largest known room temperature magnetostriction constant. The large magnetostriction constant suggests that we can manipulate the magnetic anisotropy of the material using small strains. Other research groups have grown amorphous and polycrystalline TbFe2 films; however, these films lose giant mangetostriction because of diordered atomic structure in the amorphous films and random grain orientation in the polycrystalline films. Single-crystal structure is needed to achieve the large magnetostriction, so epitaxial growth of TbFe2 thin films is necessary. The goal of this research is to grow epitaxial TbFe2 films and study the effect of film strain on magnetic anisotropy. A technique was developed to grow epitaxial TbFe2films using DC magnetron sputtering. The films were grown in a UHV system using elemental Tb and Fe sputtering targets and single-crystal Al2O3, MgO, and CaF2 substrates. (110) -oriented Mo, W, and Nb were used as buffer layers to provide the base for epitaxial growth and to prevent chemical reactions between the TbFe2 films and the substrates. On the Mo and W buffer layers the TbFe2 film is (111) -oriented but on the Nb buffer layer it is (110) -oriented. Preliminary calculation of magnetostrictive anisotropy in TbFe2(111) films predicts that compressive strain greater than 0.5% will induce perpendicular magnetization while tensile strain greater than 0.5% will induce an in- plane magnetization. Epitaxial growth on CaF2 provides compressive thermal strain of 0.51%, and SQUID measurements confirmed that these samples did have perpendicular magnetization. On the other hand, Al2O3 provides tensile thermal strain of 0.56%, and SQUID measurements showed the films on Al2O3 were in-plane. The values of strain on these three substrates were determined by strain measurement from synchrotron radiation. X-ray epitaxial quality measurements revealed a new orientation relationship, R30o, at the TbFe2

  18. Extra structurally abnormal chromosomes (ESAC) detected at amniocentesis: frequency in approximately 75,000 prenatal cytogenetic diagnoses and associations with maternal and paternal age.

    PubMed Central

    Hook, E B; Cross, P K

    1987-01-01

    We analyzed rates of extra structurally abnormal chromosomes (ESAC) detected in prenatal cytogenetic diagnoses of amniotic fluid reported to the New York Chromosome Registry. These karyotypes include both extra unidentified structurally abnormal chromosomes (EUSAC)--often denoted as "markers"--and extra identified structurally abnormal chromosomes (EISAC). The rate of all EUSAC was 0.64/1,000 (0.32-0.40/1,000 mutant and 0.23-0.32 inherited), and that of all EISAC was 0.11/1,000 (0.07/1,000 mutant and 0.04/1,000 inherited). The rate of all ESAC was approximately 0.8/1,000-0.4-0.5/1,000 mutant and 0.3-0.4/1,000 inherited. Mean +/- SD maternal age of mutant cases was 37.5 +/- 2.9, significantly greater than the value of 35.8 years in controls. A regression analysis indicated a rate of change of the log of the rate of about +0.20 with each year of maternal age between 30 and 45 years. When paternal age was introduced, the maternal age coefficient increased to about +0.25--close to that seen for 47, +21--but the paternal age coefficient was -0.06. After being matched for maternal age and year of diagnosis, the case-control difference in paternal age for 24 mutant cases was -2.4 with a 95% confidence interval of -4.6 to -0.1 years. In a regression analysis of the effects of both parental ages on the (log) rate, the maternal age coefficient was +0.25 and the paternal age coefficient was -0.06. These results are consistent with a (weak) negative paternal age effect in the face of a strong maternal age effect. Since ESAC include a heterogeneous group of abnormalities, the maternal age and paternal age trends, if not the result of statistical fluctuation or undetected biases, may involve different types of events. Data in the literature suggest that chromosomes with de novo duplicated inversions of 15p have a strong maternal age effect (but little paternal age effect). Such chromosomes, however, do not account for the active maternal age trends seen in the data analyzed here

  19. Filamentary structure and magnetic field orientation in Musca

    NASA Astrophysics Data System (ADS)

    Cox, N. L. J.; Arzoumanian, D.; André, Ph.; Rygl, K. L. J.; Prusti, T.; Men'shchikov, A.; Royer, P.; Kóspál, Á.; Palmeirim, P.; Ribas, A.; Könyves, V.; Bernard, J.-Ph.; Schneider, N.; Bontemps, S.; Merin, B.; Vavrek, R.; Alves de Oliveira, C.; Didelon, P.; Pilbratt, G. L.; Waelkens, C.

    2016-05-01

    Herschel has shown that filamentary structures are ubiquitous in star-forming regions, in particular in nearby molecular clouds associated with Gould's Belt. High dynamic range far-infrared imaging of the Musca cloud with SPIRE and PACS reveals at least two types of filamentary structures: (1) the main ~10-pc scale high column-density linear filament; and (2) low column-density striations in close proximity to the main filament. In addition, we find features with intermediate column densities (hair-like strands) that appear physically connected to the main filament. We present an analysis of this filamentary network traced by Herschel and explore its connection with the local magnetic field. We find that both the faint dust emission striations and the plane-of-the-sky (POS) magnetic field are locally oriented close to perpendicular to the high-density main filament (position angle ~25-35°). The low-density striations and strands are oriented parallel to the POS magnetic field lines, which are derived previously from optical polarization measurements of background stars and more recently from Planck observations of dust polarized emission. The position angles are 97 ± 25°, 105 ± 7°, and 105 ± 5°. From these observations, we propose a scenario in which local interstellar material in this cloud has condensed into a gravitationally-unstable filament (with "supercritical" mass per unit length) that is accreting background matter along field lines through the striations. We also compare the filamentary structure in Musca with what is seen in similar Herschel observations of the Taurus B211/3 filament system and find that there is significantly less substructure in the Musca main filament than in the B211/3 filament. We suggest that the Musca cloud may represent an earlier evolutionary stage in which the main filament has not yet accreted sufficient mass and energy to develop a multiple system of intertwined filamentary components. Herschel is an ESA space

  20. The effect of external magnetic fields on the pore structure of polyurethane foams loaded with magnetic microparticles

    NASA Astrophysics Data System (ADS)

    Schümann, M.; Seelig, N.; Odenbach, S.

    2015-10-01

    Elastic matrices loaded with magnetic microparticles are a new kind of magnetic hybrid material gaining a lot of scientific interest during the last few years. The central advantage of those materials is given by the possibility to control the mechanical properties by external stimuli, in this case external magnetic fields. Due to their extraordinary elastic properties, polyurethane foams are a promising matrix material for a new approach to synthesize such magnetic hybrid materials. A key to a deeper understanding of this new material is the investigation on how the inner structure of the hybrid material is controllable by the application of an external magnetic field during the polymerization. This paper presents a convenient method for analysis of structural changes of magnetically influenced particle loaded polyurethane foams. The geometry and size of up to 40 000 individual pores was evaluated by means of x-ray microtomography and digital image processing. A modest impact of the magnetic field on the pore structure was found with the utilized foam material, proving the convenient applicability of this method for future investigation with magnetic hybrid foams.

  1. Effects of wear on structure-sensitive magnetic properties of ceramic ferrite in contact with magnetic tape

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.; Tanaka, K.

    1985-01-01

    Wear experiments and electron microscopy and diffraction studies were conducted to examine the wear and deformed layers in single-crystal Mn-Zn (ceramic) ferrite magnetic head material in contact with magnetic tape and the effects of that contact on magnetic properties. The crystalline state of the single-crystal magnetic head was changed drastically during the sliding process. A nearly amorphous structure was produced on its wear surface. Deformation in the surficial layer of the magnetic head was a critical factor in readback signal loss above 2.5 dB. The signal output level was reduced as applied normal load was increased. Considerable plastic flow occurred on the magnetic tape surface with sliding, and the signal loss due to the tape wear was approximately 1 dB.

  2. (The relationship between microstructure and magnetic properties in high-energy permanent magnets characterized by polytwinned structures)

    SciTech Connect

    Not Available

    1992-01-01

    This report summarizes the results of a study of the relationship between microstructure and magnetic properties in a unique genre of ferromagnetic material characterized by a polysynthetically twinned structure which arises during solid state transformation. These results stem from the work over a period of approximately 27 months of a nominal 3 year grant period. The report also contains a proposal to extend the research project for an additional 3 years. The polytwinned structures produce an inhomogeneous magnetic medium in which the easy axis of magnetization varies quasi-periodically giving rise to special domain configurations which are expected to markedly influence the mechanism of magnetization reversal and hysteresis behavior of these materials in bulk or thin films. The extraordinary permanent magnet properties exhibited by the well-known Co-Pt alloys as well as the Fe-Pt and Fe-Pd systems near the equiatomic composition derive from the formation of a polytwinned microstructure.

  3. [The relationship between microstructure and magnetic properties in high-energy permanent magnets characterized by polytwinned structures

    SciTech Connect

    Not Available

    1992-07-01

    This report summarizes the results of a study of the relationship between microstructure and magnetic properties in a unique genre of ferromagnetic material characterized by a polysynthetically twinned structure which arises during solid state transformation. These results stem from the work over a period of approximately 27 months of a nominal 3 year grant period. The report also contains a proposal to extend the research project for an additional 3 years. The polytwinned structures produce an inhomogeneous magnetic medium in which the easy axis of magnetization varies quasi-periodically giving rise to special domain configurations which are expected to markedly influence the mechanism of magnetization reversal and hysteresis behavior of these materials in bulk or thin films. The extraordinary permanent magnet properties exhibited by the well-known Co-Pt alloys as well as the Fe-Pt and Fe-Pd systems near the equiatomic composition derive from the formation of a polytwinned microstructure.

  4. Tuning the magnetic anisotropy in single-layer crystal structures

    NASA Astrophysics Data System (ADS)

    Torun, E.; Sahin, H.; Bacaksiz, C.; Senger, R. T.; Peeters, F. M.

    2015-09-01

    The effect of an applied electric field and the effect of charging are investigated on the magnetic anisotropy (MA) of various stable two-dimensional (2D) crystals such as graphene, FeCl2, graphone, fluorographene, and MoTe2 using first-principles calculations. We found that the magnetocrystalline anisotropy energy of Co-on-graphene and Os-doped-MoTe2 systems change linearly with electric field, opening the possibility of electric field tuning MA of these compounds. In addition, charging can rotate the easy-axis direction of Co-on-graphene and Os-doped-MoTe2 systems from the out-of-plane (in-plane) to in-plane (out-of-plane) direction. The tunable MA of the studied materials is crucial for nanoscale electronic technologies such as data storage and spintronics devices. Our results show that controlling the MA of the mentioned 2D crystal structures can be realized in various ways, and this can lead to the emergence of a wide range of potential applications where the tuning and switching of magnetic functionalities are important.

  5. Role of structurally and magnetically modified nanoclusters in colossal magnetoresistance

    PubMed Central

    Tao, Jing; Niebieskikwiat, Dario; Jie, Qing; Schofield, Marvin A.; Wu, Lijun; Li, Qiang; Zhu, Yimei

    2011-01-01

    It is generally accepted that electronic and magnetic phase separation is the origin of many of exotic properties of strongly correlated electron materials, such as colossal magnetoresistance (CMR), an unusually large variation in the electrical resistivity under applied magnetic field. In the simplest picture, the two competing phases are those associated with the material state on either side of the phase transition. Those phases would be paramagnetic insulator and ferromagnetic metal for the CMR effect in doped manganites. It has been speculated that a critical component of the CMR phenomenon is nanoclusters with quite different properties than either of the terminal phases during the transition. However, the role of these nanoclusters in the CMR effect remains elusive because the physical properties of the nanoclusters are hard to measure when embedded in bulk materials. Here we show the unexpected behavior of the nanoclusters in the CMR compound La1-xCaxMnO3 (0.4 ≤ x < 0.5) by directly correlating transmission electron microscopy observations with bulk measurements. The structurally modified nanoclusters at the CMR temperature were found to be ferromagnetic and exhibit much higher electrical conductivity than previously proposed. Only at temperatures much below the CMR transition, the nanoclusters are antiferromagnetic and insulating. These findings substantially alter the current understanding of these nanoclusters on the material’s functionality and would shed light on the microscopic study on the competing spin-lattice-charge orders in strongly correlated systems. PMID:22160678

  6. Nonlinear dynamics of drift structures in a magnetized dissipative plasma

    NASA Astrophysics Data System (ADS)

    Aburjania, G. D.; Rogava, D. L.; Kharshiladze, O. A.

    2011-06-01

    A study is made of the nonlinear dynamics of solitary vortex structures in an inhomogeneous magnetized dissipative plasma. A nonlinear transport equation for long-wavelength drift wave structures is derived with allowance for the nonuniformity of the plasma density and temperature equilibria, as well as the magnetic and collisional viscosity of the medium and its friction. The dynamic equation describes two types of nonlinearity: scalar (due to the temperature inhomogeneity) and vector (due to the convectively polarized motion of the particles of the medium). The equation is fourth order in the spatial derivatives, in contrast to the second-order Hasegawa-Mima equations. An analytic steady solution to the nonlinear equation is obtained that describes a new type of solitary dipole vortex. The nonlinear dynamic equation is integrated numerically. A new algorithm and a new finite difference scheme for solving the equation are proposed, and it is proved that the solution so obtained is unique. The equation is used to investigate how the initially steady dipole vortex constructed here behaves unsteadily under the action of the factors just mentioned. Numerical simulations revealed that the role of the vector nonlinearity is twofold: it helps the dispersion or the scalar nonlinearity (depending on their magnitude) to ensure the mutual equilibrium and, thereby, promote self-organization of the vortical structures. It is shown that dispersion breaks the initial dipole vortex into a set of tightly packed, smaller scale, less intense monopole vortices-alternating cyclones and anticyclones. When the dispersion of the evolving initial dipole vortex is weak, the scalar nonlinearity symmetrically breaks a cyclone-anticyclone pair into a cyclone and an anticyclone, which are independent of one another and have essentially the same intensity, shape, and size. The stronger the dispersion, the more anisotropic the process whereby the structures break: the anticyclone is more intense

  7. Nonlinear dynamics of drift structures in a magnetized dissipative plasma

    SciTech Connect

    Aburjania, G. D.; Rogava, D. L.; Kharshiladze, O. A.

    2011-06-15

    A study is made of the nonlinear dynamics of solitary vortex structures in an inhomogeneous magnetized dissipative plasma. A nonlinear transport equation for long-wavelength drift wave structures is derived with allowance for the nonuniformity of the plasma density and temperature equilibria, as well as the magnetic and collisional viscosity of the medium and its friction. The dynamic equation describes two types of nonlinearity: scalar (due to the temperature inhomogeneity) and vector (due to the convectively polarized motion of the particles of the medium). The equation is fourth order in the spatial derivatives, in contrast to the second-order Hasegawa-Mima equations. An analytic steady solution to the nonlinear equation is obtained that describes a new type of solitary dipole vortex. The nonlinear dynamic equation is integrated numerically. A new algorithm and a new finite difference scheme for solving the equation are proposed, and it is proved that the solution so obtained is unique. The equation is used to investigate how the initially steady dipole vortex constructed here behaves unsteadily under the action of the factors just mentioned. Numerical simulations revealed that the role of the vector nonlinearity is twofold: it helps the dispersion or the scalar nonlinearity (depending on their magnitude) to ensure the mutual equilibrium and, thereby, promote self-organization of the vortical structures. It is shown that dispersion breaks the initial dipole vortex into a set of tightly packed, smaller scale, less intense monopole vortices-alternating cyclones and anticyclones. When the dispersion of the evolving initial dipole vortex is weak, the scalar nonlinearity symmetrically breaks a cyclone-anticyclone pair into a cyclone and an anticyclone, which are independent of one another and have essentially the same intensity, shape, and size. The stronger the dispersion, the more anisotropic the process whereby the structures break: the anticyclone is more intense

  8. Investigating individual differences in brain abnormalities in autism.

    PubMed Central

    Salmond, C H; de Haan, M; Friston, K J; Gadian, D G; Vargha-Khadem, F

    2003-01-01

    Autism is a psychiatric syndrome characterized by impairments in three domains: social interaction, communication, and restricted and repetitive behaviours and interests. Recent findings implicate the amygdala in the neurobiology of autism. In this paper, we report the results of a series of novel experimental investigations focusing on the structure and function of the amygdala in a group of children with autism. The first section attempts to determine if abnormality of the amygdala can be identified in an individual using magnetic resonance imaging in vivo. Using single-case voxel-based morphometric analyses, abnormality in the amygdala was detected in half the children with autism. Abnormalities in other regions were also found. In the second section, emotional modulation of the startle response was investigated in the group of autistic children. Surprisingly, there were no significant differences between the patterns of emotional modulation of the startle response in the autistic group compared with the controls. PMID:12639337

  9. Associated brain abnormalities in patients with corpus callosum anomalies.

    PubMed

    Tekgül, H; Dizdarer, G; Yalman, O; Sener, N; Yünten, N; Tütüncüoğlu, S

    1999-01-01

    Forty-nine patients with corpus callosum (CC) anomalies were evaluated in terms of the clinical features and magnetic resonance imaging (MRI) findings. CC anomalies were classified as CC agenesis: 6 (12%), CC hypogenesis: 5 (10%), and CC hypoplasia: 38 (78%). In the CC hypoplasia group the mean value of the genu thickness of the CC was 0.29 +/- 0.1 cm, which was less than the normal value of the age-matched normal children (normal range: 0.6-1.2 cm). The associated brain abnormalities were in five distinct groups: gray matter abnormalities, white matter abnormalities, midline brain structure defects, cortical atrophy, and encephalomalacia. There was no uniformity for the clinical spectrum of CC anomalies. Microcephaly, developmental delay and seizures were the prominent findings in patients. The clinical features were more severe in cases with associated brain anomalies.

  10. Investigation of the structure and stability of the lower atmosphere by microwave ground-based sensing over Nizhniy Novgorod, Russia during abnormally warm winter 2013 - 2014

    NASA Astrophysics Data System (ADS)

    Karashtin, Dmitriy; Berezin, Evgeny; Kulikov, Mikhail; Feigin, Alexander

    2014-05-01

    The monitoring of the lower atmosphere structure and stability is required for studying the processes of the convection in the atmosphere, determining the mutual influence of global climate change trends and the current state of regional climate systems, which have an impact on the appearance of dangerous meteorological events (heavy rains, thunderstorms, hail, floods, squalls, tornadoes, etc). There are many methods of measuring structure of the atmosphere: contact (rocket and balloon), contactless - active (lidar) and passive (radiometric), with the placement of the instrumentation on the satellite, airplanes and the Earth's surface (ground-based). For the convection processes study in order to predict dangerous meteorological events the ground-based radiometric sensing of the structure of the lower atmosphere seems to be the most suitable due to higher time and spatial resolution. This report discusses the peculiarities of the structure of the lower atmosphere over Nizhniy Novgorod, Russia during the abnormally warm winter 2013 - 2014 retrieved from measurements by radiometric complex HATPRO-G3 by Radiometer Physics GmbH. This complex gives vertical thermal and water vapor profiles of the lower atmosphere (0 - 10 km) with time resolution of a few minutes, horizontally resolution of about 10 kilometers and vertically resolution of about 100 meters. The analysis of the structure and stability of the lower atmosphere is based on the vertical distribution of virtual potential temperature derived from these measurements under the hydrostatic approximation. Also the comparison of the results for the abnormally winter 2013 - 2014 and the data computed from the Weather Research and Forecasting (WRF) Model (http://www.wrf-model.org) for winter 2011 - 2012 is discussed.

  11. High frequency of rare structural chromosome abnormalities at relapse of cytogenetically normal acute myeloid leukemia with FLT3 internal tandem duplication.

    PubMed

    Gourdin, Theodore S; Zou, Ying; Ning, Yi; Emadi, Ashkan; Duong, Vu H; Tidwell, Michael L; Chen, Ching; Rassool, Feyruz V; Baer, Maria R

    2014-01-01

    FLT3 internal tandem duplication (ITD) mutations are present in acute myeloid leukemia (AML) in 30% of patients with acute myeloid leukemia (AML), most commonly in those with a normal karyotype, and are associated with short relapse-free survival. Both in vitro and in vivo studies of FLT3-ITD cell lines have demonstrated reactive oxygen species-mediated DNA double-strand breaks and associated error-prone DNA repair as a mechanism of genomic instability, and we hypothesized that genomic instability might be manifested by cytogenetic changes at relapse of FLT3-ITD AML. We retrospectively reviewed charts of patients with cytogenetically normal (CN) FLT3-ITD AML treated at the University of Maryland Greenebaum Cancer Center, with attention to metaphase analysis results at relapse. Cytogenetic data were available from first and, when applicable, subsequent relapses for 15 patients diagnosed with CN FLT3-ITD AML. Among 12 patients with documented FLT3-ITD at first and, when applicable, subsequent relapse, 10 had cytogenetic changes, including nine with rare structural abnormalities. The high frequency of rare structural chromosome abnormalities at relapse in our case series supports a role of genomic instability in the genesis of relapse, and suggests that reactive oxygen species-generating and DNA repair pathways might be therapeutic targets in FLT3-ITD AML. PMID:25441683

  12. Radio polarization and magnetic field structure in M 101

    NASA Astrophysics Data System (ADS)

    Berkhuijsen, E. M.; Urbanik, M.; Beck, R.; Han, J. L.

    2016-04-01

    We observed total and polarized radio continuum emission from the spiral galaxy M 101 at λλ 6.2 cm and 11.1 cm with the Effelsberg telescope. The angular resolutions are 2.´ 5 (=5.4 kpc) and 4.´ 4 (=9.5 kpc), respectively. We use these data to study various emission components in M 101 and properties of the magnetic field. Separation of thermal and non-thermal emission shows that the thermal emission is closely correlated with the spiral arms, while the non-thermal emission is more smoothly distributed indicating diffusion of cosmic ray electrons away from their places of origin. The radial distribution of both emissions has a break near R = 16 kpc (=7.´ 4), where it steepens to an exponential scale length of L ≃ 5 kpc, which is about 2.5 times smaller than at R< 16 kpc. The distribution of the polarized emission has a broad maximum near R = 12 kpc and beyond R = 16 kpc also decreases with L ≃ 5 kpc. It seems that near R = 16 kpc a major change in the structure of M 101 takes place, which also affects the distributions of the strength of the random and ordered magnetic field. Beyond R = 16 kpc the radial scale length of both fields is about 20 kpc, which implies that they decrease to about 0.3 μG at R = 70 kpc, which is the largest optical extent. The equipartition strength of the total field ranges from nearly 10 μG at R< 2 kpc to 4 μG at R = 22-24 kpc. As the random field dominates in M 101 (Bran/Bord ≃ 2.4), wavelength-independent polarization is the main polarization mechanism. We show that energetic events causing H i shells of mean diameter < 625 pc could partly be responsible for this. At radii < 24 kpc, the random magnetic field depends on the star formation rate/area, ΣSFR, with a power-law exponent of b = 0.28 ± 0.02. The ordered magnetic field is generally aligned with the spiral arms with pitch angles that are about 8° larger than those of H i filaments. Based on observations with the 100 m telescope of the MPIfR at Effelsberg

  13. Low cost composite structures for superconducting magnetic energy storage systems

    SciTech Connect

    Rix, C. ); McColskey, D. ); Acree, R. )

    1994-07-01

    As part of the Superconducting Magnetic Energy Storage/Engineering Test Model (SMES-ETM) programs, design, analysis, fabrication and test programs were conducted to evaluate the low cost manufacturing of Fiberglass Reinforced Plastic (FRP) beams for usage as major components of the structural and electrical insulation systems. These studies utilized pultrusion process technologies and vinylester resins to produce large net sections at costs significantly below that of conventional materials. Demonstration articles incorporating laminate architectures and design details representative of SMES-ETM components were fabricated using the pultrusion process and epoxy, vinylester, and polyester resin systems. The mechanical and thermal properties of these articles were measured over the temperature range from 4 K to 300 K. The results of these tests showed that the pultruded, vinylester components have properties comparable to those of currently used materials, such as G-10, and are capable of meeting the design requirements for the SMES-ETM system.

  14. Low cost composite structures for superconducting magnetic energy storage systems

    NASA Astrophysics Data System (ADS)

    Rix, Craig; McColskey, David; Acree, Robert

    1994-07-01

    As part of the Superconducting Magnetic Energy Storage/Engineering Test Model (SMES-ETM) program, design, analysis, fabrication and test programs were conducted to evaluate the low cost manufacturing of Fiberglass Reinforced Plastic (FRP) beams for usage as major components of the structural and electrical insulation systems. These studies utilized pultrusion process technologies and vinylester resins to produce large net sections at costs significantly below that of conventional materials. Demonstration articles incorporating laminate architectures and design details representative of SMES-ETM components were fabricated using the pultrusion process and epoxy, vinylester, and polyester resin systems. The mechanical and thermal properties of these articles were measured over the temperature range from 4 K to 300 K. The results of these tests showed that the pultruded, vinylester components have properties comparable to those of currently used materials, such as G-10, and are capable of meeting the design requirements for the SMES-ETM system.

  15. Magnetic structure of Gd2Ti2O7

    NASA Astrophysics Data System (ADS)

    Brammall, M. I.; Briffa, A. K. R.; Long, M. W.

    2011-02-01

    We attempt to solve the magnetic structure of the gadolinium analog of “spin-ice” using a mixture of experimental and theoretical assumptions. The eventual predictions are essentially consistent with both the Mössbauer and neutron measurements but are unrelated to previous proposals. We find two possible distinct states, one of which is coplanar and the other is fully three-dimensional. We predict that close to the initial transition the preferred state is coplanar, but that at the lowest temperature the ground state becomes fully three-dimensional. Unfortunately, the energetics are presumed to be complicated. There is a dominant nearest-neighbor Heisenberg interaction, but then a compromise solution for lifting the final degeneracy resulting from a competition between second-neighbor Heisenberg interactions and direct dipolar interactions on similar energy scales.

  16. Contact-area metrology of magnetic tunneling junction structures

    NASA Astrophysics Data System (ADS)

    Zhong, Tom; Liu, Daniel; Moran, Amit; Levkovitch, Michael; Har-Zvi, Michael; Burkhardt, Bob

    2006-03-01

    Magneto-resistive Random Access Memory (MRAM), considered the leading candidate for the next generation of universal memory, has moved from research to pilot production. Commercialization of the MRAM devices in mobile computing, cell phones, portable recording and other playback devices, home computing, consumer electronics, enterprise computing and telecommunications, promise to bring in annual revenues exceeding $50 billion during the coming years. CD-SEM correlation of contact physical Critical Dimension to Magnetic Tunneling Junction (MTJ) resistance is critical for MRAM device performance. This paper focuses on a new two-dimensional metric that more accurately characterizes MTJ resistance by calculating total contact area of unique and complex structures. We consider the advantages of the Contact Area metric for measurement of complicated shapes. We illustrate that introduction of the new metric allows for improvement in process control for critical contacts.

  17. Association between chronic stress-induced structural abnormalities in Ranvier nodes and reduced oligodendrocyte activity in major depression

    PubMed Central

    Miyata, Shingo; Taniguchi, Manabu; Koyama, Yoshihisa; Shimizu, Shoko; Tanaka, Takashi; Yasuno, Fumihiko; Yamamoto, Akihide; Iida, Hidehiro; Kudo, Takashi; Katayama, Taiichi; Tohyama, Masaya

    2016-01-01

    Repeated stressful events are associated with the onset of major depressive disorder (MDD). We previously showed oligodendrocyte (OL)-specific activation of the serum/glucocorticoid-regulated kinase (SGK)1 cascade, increased expression of axon-myelin adhesion molecules, and elaboration of the oligodendrocytic arbor in the corpus callosum of chronically stressed mice. In the current study, we demonstrate that the nodes and paranodes of Ranvier in the corpus callosum were narrower in these mice. Chronic stress also led to diffuse redistribution of Caspr and Kv 1.1 and decreased the activity in white matter, suggesting a link between morphological changes in OLs and inhibition of axonal activity. OL primary cultures subjected to chronic stress resulted in SGK1 activation and translocation to the nucleus, where it inhibited the transcription of metabotropic glutamate receptors (mGluRs). Furthermore, the cAMP level and membrane potential of OLs were reduced by chronic stress exposure. We showed by diffusion tensor imaging that the corpus callosum of patients with MDD exhibited reduced fractional anisotropy, reflecting compromised white matter integrity possibly caused by axonal damage. Our findings suggest that chronic stress disrupts the organization of the nodes of Ranvier by suppressing mGluR activation in OLs, and that specific white matter abnormalities are closely associated with MDD onset. PMID:26976207

  18. Fyn kinase genetic ablation causes structural abnormalities in mature retina and defective Müller cell function.

    PubMed

    Chavez-Solano, Marbella; Ibarra-Sanchez, Alfredo; Treviño, Mario; Gonzalez-Espinosa, Claudia; Lamas, Monica

    2016-04-01

    Fyn kinase is widely expressed in neuronal and glial cells of the brain, where it exerts multiple functional roles that affect fundamental physiological processes. The aim of our study was to investigate the, so far unknown, functional role of Fyn in the retina. We report that Fyn is expressed, in vivo, in a subpopulation of Müller glia. We used a mouse model of Fyn genetic ablation and Müller-enriched primary cultures to demonstrate that Fyn deficiency induces morphological alterations in the mature retina, a reduction in the thickness of the outer and inner nuclear layers and alterations in postnatal Müller cell physiology. These include shortening of Müller cell processes, a decrease in cell proliferation, inactivation of the Akt signal transduction pathway, a reduced number of focal adhesions points and decreased adhesion of these cells to the ECM. As abnormalities in Müller cell physiology have been previously associated to a compromised retinal function we evaluated behavioral responses to visual stimulation. Our results associate Fyn deficiency with impaired visual optokinetic responses under scotopic and photopic light conditions. Our study reveals novel roles for Fyn kinase in retinal morphology and Müller cell physiology and suggests that Fyn is required for optimal visual processing.

  19. Fyn kinase genetic ablation causes structural abnormalities in mature retina and defective Müller cell function.

    PubMed

    Chavez-Solano, Marbella; Ibarra-Sanchez, Alfredo; Treviño, Mario; Gonzalez-Espinosa, Claudia; Lamas, Monica

    2016-04-01

    Fyn kinase is widely expressed in neuronal and glial cells of the brain, where it exerts multiple functional roles that affect fundamental physiological processes. The aim of our study was to investigate the, so far unknown, functional role of Fyn in the retina. We report that Fyn is expressed, in vivo, in a subpopulation of Müller glia. We used a mouse model of Fyn genetic ablation and Müller-enriched primary cultures to demonstrate that Fyn deficiency induces morphological alterations in the mature retina, a reduction in the thickness of the outer and inner nuclear layers and alterations in postnatal Müller cell physiology. These include shortening of Müller cell processes, a decrease in cell proliferation, inactivation of the Akt signal transduction pathway, a reduced number of focal adhesions points and decreased adhesion of these cells to the ECM. As abnormalities in Müller cell physiology have been previously associated to a compromised retinal function we evaluated behavioral responses to visual stimulation. Our results associate Fyn deficiency with impaired visual optokinetic responses under scotopic and photopic light conditions. Our study reveals novel roles for Fyn kinase in retinal morphology and Müller cell physiology and suggests that Fyn is required for optimal visual processing. PMID:26808221

  20. Magnetic stimulation for non-homogeneous biological structures

    PubMed Central

    Krasteva, Vessela T; Papazov, Sava P; Daskalov, Ivan K

    2002-01-01

    Background Magnetic stimulation has gained relatively wide application in studying nervous system structures. This technology has the advantage of reduced excitation of sensory nerve endings, and hence results in quasi-painless action. It has become clinically accepted modality for brain stimulation. However, theoretical and practical solutions for assessment of induced current distribution need more detailed and accurate consideration. Some possible analyses are proposed for distribution of the current induced from excitation current contours of different shape and disposition. Relatively non-difficult solutions are shown, applicable for two- and three-dimensional analysis. Methods The boundary conditions for field analysis by the internal Dirichlet problem are introduced, based on the vector potential field excited by external current coils. The feedback from the induced eddy currents is neglected. Finite element modeling is applied for obtaining the electromagnetic fields distribution in a non-homogeneous domain. Results The distributions were obtained in a non-homogeneous structure comprised of homogeneous layers. A tendency was found of the induced currents to follow paths in lower resistivity layers, deviating from the expected theoretical course for a homogeneous domain. Current density concentrations occur at the boundary between layers, suggesting the possibility for focusing on, or predicting of, a zone of stimulation. Conclusion The theoretical basis and simplified approach for generation of 3D FEM networks for magnetic stimulation analysis are presented, applicable in non-homogeneous and non-linear media. The inconveniences of introducing external excitation currents are avoided. Thus, the possibilities are improved for analysis of distributions induced by time-varying currents from contours of various geometry and position with respect to the medium. PMID:12437784

  1. Influence of Ce-Substitution on Structural, Magnetic and Electrical Properties of Cobalt Ferrite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hashhash, A.; Kaiser, M.

    2016-01-01

    Nano-crystalline samples of cerium substituted cobalt ferrites with chemical formula CoCe x Fe2- x O4 (0.0 ≤ x ≤ 0.1) were prepared using the citrate auto-combustion method. The prepared ferrites were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy spectra (FTIR), transmission electron microscopy (TEM), and a vibrating sample magnetometer (VSM). The XRD patterns and FTIR spectra confirm that the prepared samples reveal the formation of a single-phase spinel structure. TEM micrographs showed that the particles are made up of spherical and elongated nano-metric shapes. A limitation of the size of nanoparticles is observed as the Ce3+ concentration increases. VSM measurements showed that the coercivity H c and magnetization values M s are strongly dependent on Ce3+ content and particle size. The values of H c lie in the range of (411-1600 G), which suggest that these samples are convenient for different applications. The alternating current electrical conductivity ( σ), dielectric permittivities ( ɛ', ɛ″), and dielectric loss tangent (tan δ) were studied at different ranges of frequency and temperature. The relation of conductivity with temperature revealed a semiconductor to semi-metallic behavior as cerium concentration increases. The variation in (tan δ) with frequency at different temperature shows abnormal behavior with more than one relaxation peak. The conduction mechanism used in the present study has been discussed in the light of cation-anion-cation interactions over the octahedral B-site.

  2. Magnetic resonance microscopy of renal and biliary abnormalities in excised tissues from a mouse model of autosomal recessive polycystic kidney disease.

    PubMed

    Lee, Choong H; O'Connor, Amber K; Yang, Chaozhe; Tate, Joshua M; Schoeb, Trenton R; Flint, Jeremy J; Blackband, Stephen J; Guay-Woodford, Lisa M

    2015-08-01

    Polycystic kidney disease (PKD) is transmitted as either an autosomal dominant or recessive trait and is a major cause of renal failure and liver fibrosis. The cpk mouse model of autosomal recessive PKD (ARPKD) has been extensively characterized using standard histopathological techniques after euthanasia. In the current study, we sought to validate magnetic resonance microscopy (MRM) as a robust tool for assessing the ARPKD phenotype. We used MRM to evaluate the liver and kidney of wild-type and cpk animals at resolutions <100 μm and generated three-dimensional (3D) renderings for pathological evaluation. Our study demonstrates that MRM is an excellent method for evaluating the complex, 3D structural defects in this ARPKD mouse model. We found that MRM was equivalent to water displacement in assessing kidney volume. Additionally, using MRM we demonstrated for the first time that the cpk liver exhibits less extensive ductal arborization, that it was reduced in volume, and that the ductal volume was disproportionately smaller. Histopathology indicates that this is a consequence of bile duct malformation. With its reduced processing time, volumetric information, and 3D capabilities, MRM will be a useful tool for future in vivo and longitudinal studies of disease progression in ARPKD. In addition, MRM will provide a unique tool to determine whether the human disease shares the newly appreciated features of the murine biliary phenotype. PMID:26320214

  3. Magnetic resonance microscopy of renal and biliary abnormalities in excised tissues from a mouse model of autosomal recessive polycystic kidney disease

    PubMed Central

    Lee, Choong H; O’Connor, Amber K; Yang, Chaozhe; Tate, Joshua M; Schoeb, Trenton R; Flint, Jeremy J; Blackband, Stephen J; Guay-Woodford, Lisa M

    2015-01-01

    Polycystic kidney disease (PKD) is transmitted as either an autosomal dominant or recessive trait and is a major cause of renal failure and liver fibrosis. The cpk mouse model of autosomal recessive PKD (ARPKD) has been extensively characterized using standard histopathological techniques after euthanasia. In the current study, we sought to validate magnetic resonance microscopy (MRM) as a robust tool for assessing the ARPKD phenotype. We used MRM to evaluate the liver and kidney of wild-type and cpk animals at resolutions <100 μm and generated three-dimensional (3D) renderings for pathological evaluation. Our study demonstrates that MRM is an excellent method for evaluating the complex, 3D structural defects in this ARPKD mouse model. We found that MRM was equivalent to water displacement in assessing kidney volume. Additionally, using MRM we demonstrated for the first time that the cpk liver exhibits less extensive ductal arborization, that it was reduced in volume, and that the ductal volume was disproportionately smaller. Histopathology indicates that this is a consequence of bile duct malformation. With its reduced processing time, volumetric information, and 3D capabilities, MRM will be a useful tool for future in vivo and longitudinal studies of disease progression in ARPKD. In addition, MRM will provide a unique tool to determine whether the human disease shares the newly appreciated features of the murine biliary phenotype. PMID:26320214

  4. Regional Microstructural and Volumetric Magnetic Resonance Imaging (MRI) Abnormalities in the Corpus Callosum of Neonates With Congenital Heart Defect Undergoing Cardiac Surgery.

    PubMed

    Hagmann, Cornelia; Singer, Jitka; Latal, Beatrice; Knirsch, Walter; Makki, Malek

    2016-03-01

    The purpose of the study is to investigate the structural development of the corpus callosum in term neonates with congenital heart defect before and after surgery using diffusion tensor imaging and 3-dimensional T1-weighted magnetic resonance imaging (MRI). We compared parallel and radial diffusions, apparent diffusion coefficient (ADC), fractional anisotropy, and volume of 5 substructures of the corpus callosum: genu, rostral body, body, isthmus, and splenium. Compared to healthy controls, we found a significantly lower volume of the splenium and total corpus callosum and a higher radial diffusion and lower fractional anisotropy in the splenium of patients presurgery; a lower volume in all substructures in the postsurgery group; higher radial diffusion in the rostral body, body, and splenium; and a higher apparent diffusion coefficient in the splenium of postsurgery patients. Similar fractional anisotropy changes in congenital heart defect patients were reported in preterm infants. Our findings in apparent diffusion coefficient in the splenium of these patients (pre and postsurgery) are comparable to findings in preterm neonates with psychomotor delay. Delayed maturation of the isthmus was also reported in preterm infants.

  5. Improvement of neutral beam injection heating efficiency with magnetic field well structures in a tokamak with a low magnetic field

    NASA Astrophysics Data System (ADS)

    Kim, S. K.; Na, D. H.; Lee, J. W.; Yoo, M. G.; Kim, H.-S.; Hwang, Y. S.; Hahm, T. S.; Na, Yong-Su

    2016-10-01

    Magnetic well structures are introduced as an effective means to reduce the prompt loss of fast ions, the so-called first orbit loss from neutral beam injection (NBI), which is beneficial to tokamaks with a low magnetic field strength such as small spherical torus devices. It is found by single-particle analysis that this additional field structure can modify the gradient of the magnetic field to reduce the shift of the guiding center trajectory of the fast ion. This result is verified by a numerical calculation of following the fast ion’s trajectory. We apply this concept to the Versatile Experiment Spherical Torus [1], where NBI is under design for the purpose of achieving high-performance plasma, to evaluate the effect of the magnetic well structure on NBI efficiency. A 1D NBI analysis code and the NUBEAM code are employed for detailed NBI calculations. The simulation results show that the orbit loss can be reduced by 70%-80%, thereby improving the beam efficiency twofold compared with the reference case without the well structure. The well-shaped magnetic field structure in the low-field side can significantly decrease orbit loss by broadening the non-orbit loss region and widening the range of the velocity direction, thus improving the heating efficiency. It is found that this magnetic well can also improve orbit loss during the slowing down process.

  6. Magnetic susceptibility, specific heat and magnetic structure of CuNi{sub 2}(PO{sub 4}){sub 2}

    SciTech Connect

    Escobal, Jaione; Pizarro, Jose L.; Mesa, Jose L. . E-mail: joseluis.mesa@ehu.es; Larranaga, Aitor; Fernandez, Jesus Rodriguez; Arriortua, Maria I.; Rojo, Teofilo

    2006-10-15

    CuNi{sub 2}(PO{sub 4}){sub 2} phosphate has been synthesized by the ceramic method at 800 deg. C in air. The crystal structure consists of a three-dimensional skeleton constructed from MO{sub 4} (M{sup II} =Cu and Ni) planar squares and M{sub 2}O{sub 8} dimers with square pyramidal geometry, which are interconnected by (PO{sub 4}){sup 3-} oxoanions with tetrahedral geometry. The magnetic behavior has been studied on powdered sample by using susceptibility, specific heat and neutron diffraction data. The bimetallic copper(II)-nickel(II) orthophosphate exhibits a three-dimensional magnetic ordering at, approximately, 29.8 K. However, its complex crystal structure hampers any parametrization of the J-exchange parameter. The specific heat measurements exhibit a three-dimensional magnetic ordering ({lambda}-type) peak at 29.5 K. The magnetic structure of this phosphate shows ferromagnetic interactions inside the Ni{sub 2}O{sub 8} dimers, whereas the sublattice of Cu(II) ions presents antiferromagnetic couplings along the y-axis. The change of the sign in the magnetic unit-cell, due to the [1/2, 0, 1/2] propagation vector determines a purely antiferromagnetic structure. - Graphical abstract: Magnetic structure of CuNi2(PO4)2.

  7. Quantum Oscillations of the Nanoscale Structural Inhomogeneities of the Domain Wall in Magnetic Bubble.

    PubMed

    Shevchenko, A B; Barabash, M Yu

    2015-12-01

    It is shown that at low temperatures, quantum oscillations of nanoscale structural inhomogeneities (the vertical Bloch line and the Bloch point) occur in the domain walls of cylindrical magnetic domains formed in a uniaxial magnetic film with strong magnetic anisotropy. The conditions for the excitation of these oscillations are determined.

  8. A magnetic-piezoelectric smart material-structure utilizing magnetic force interaction to optimize the sensitivity of current sensing

    NASA Astrophysics Data System (ADS)

    Yeh, Po-Chen; Chung, Tien-Kan; Lai, Chen-Hung; Wang, Chieh-Min

    2016-01-01

    This paper presents a magnetic-piezoelectric smart material-structure using a novel magnetic-force-interaction approach to optimize the sensitivity of conventional piezoelectric current sensing technologies. The smart material-structure comprises a CuBe-alloy cantilever beam, a piezoelectric PZT sheet clamped to the fixed end of the beam, and an NdFeB permanent magnet mounted on the free end of the beam. When the smart material-structure is placed close to an AC conductor, the magnet on the beam of the smart structure experiences an alternating magnetic attractive and repulsive force produced by the conductor. Thus, the beam vibrates and subsequently generates a strain in the PZT sheet. The strain produces a voltage output because of the piezoelectric effect. The magnetic force interaction is specifically enhanced through the optimization approach (i.e., achieved by using SQUID and machining method to reorient the magnetization to different directions to maximize the magnetic force interaction). After optimizing, the beam's vibration amplitude is significantly enlarged and, consequently, the voltage output is substantially increased. The experimental results indicated that the smart material-structure optimized by the proposed approach produced a voltage output of 4.01 Vrms with a sensitivity of 501 m Vrms/A when it was placed close to a conductor with a current of 8 A at 60 Hz. The optimized voltage output and sensitivity of the proposed smart structure were approximately 316 % higher than those (1.27 Vrms with 159 m Vrms/A) of representative piezoelectric-based current sensing technologies presented in other studies. These improvements can significantly enable the development of more self-powered wireless current sensing applications in the future.

  9. Study of local structure and magnetism in high-T(sub c) copper oxide superconductors

    NASA Technical Reports Server (NTRS)

    Budnick, J. I.; Tan, Z.; Filipkowski, M.; Niedermayer, CH.; Glueckler, H.; Simon, R.; Golnik, A.; Rauer, M.; Recknagel, E.; Weidinger, A.

    1990-01-01

    The muon spin rotation (MUSR) study of local magnetism of Sr-doped La2CuO4 is reviewed. Emphasis is placed on magnetic order as detected by local and bulk probes with local atomic environments studied by x ray absorption fine structure (XAFS). Correlations between the MUSR study of local magnetic ordering and the bulk magnetization study are presented along with a discussion of the dependence upon oxygen stoichiometry. Results are presented for both superconducting phases and magnetic phases. Recent data which reveals the existence of local magnetic ordering in the hydrogen-doped YBa2Cu3O7 system are also discussed.

  10. Dietary Wolfberry Ameliorates Retinal Structure Abnormalities in db/db Mice at the Early Stage of Diabetes

    PubMed Central

    Tang, Ling; Zhang, Yunong; Jiang, Yu; Willard, Lloyd; Ortiz, Edlin; Wark, Logan; Medeiros, Denis; Lin, Dingbo

    2011-01-01

    Hyperglycemia-linked oxidative stress and/or consequent endoplasmic reticulum stress are the causative factors of pathogenesis of diabetic retinopathy. Dietary bioactive components which mitigate oxidative stress may serve as potential chemopreventative agents to prevent or slow down the disease progression. Wolfberry is a traditional Asian fruit consumed for years to prevent aging eye diseases in Asian countries. Here we report that dietary wolfberry ameliorated mouse retinal abnormality at the early stage of type 2 diabetes in db/db mice. Male mice at 6 weeks of age were fed the control diet with or without 1 % (kCal) wolfberry for 8 weeks. Dietary wolfberry restored the thickness of the whole retina, in particular the inner nuclear layer and photoreceptor layer, and the integrity of retinal pigment epithelia (RPE), and the ganglion cell number in db/db mice. Western blotting of whole retinal cell lysates revealed that addition of wolfberry lowered expression of endoplasmic reticulum (ER) stress biomarkers BiP, PERK, ATF6, and caspase-12; and restored AMPK, thioredoxin, Mn SOD, and FOXO3α activities. To determine if our observations were due to the high contents of zeaxanthin and lutein in wolfberry additional studies using these carotenoids were conducted. Using the human adult diploid RPE cell line ARPE-19 we demonstrated that both zeaxanthin and lutein could mimic wolfberry preventive effect on activation of AMPK, thioredoxin, Mn SOD, FOXO3α activities, normalize cellular reactive oxygen species, and attenuate ER stress in ARPE-19 cells exposed to a high glucose challenge. The zeaxanthin preventive effect was abolished by siRNA knockdown of AMPKα. These results suggested that AMPK activation appeared to play a key role in upregulated expression of thioredoxin and Mn SOD, and mitigation of cellular oxidative stress and/or ER stress by wolfberry and zeaxanthin and/or lutein. Taken together, dietary wolfberry on retinal protection in diabetic mice is, at least

  11. Magnetization reversal induced by in-plane current in Ta/CoFeB/MgO structures with perpendicular magnetic easy axis

    SciTech Connect

    Zhang, C.; Yamanouchi, M. Ikeda, S.; Sato, H.; Fukami, S.; Matsukura, F.; Ohno, H.

    2014-05-07

    We investigate in-plane current-induced magnetization reversal under an in-plane magnetic field in Hall bar shaped devices composed of Ta/CoFeB/MgO structures with perpendicular magnetic easy axis. The observed relationship between the directions of current and magnetization switching and Ta thickness dependence of magnetization switching current are accordance with those for magnetization reversal by spin transfer torque originated from the spin Hall effect in the Ta layer.

  12. Elusive Magnetic Structures in the Sun and Solar-Type Stars

    NASA Astrophysics Data System (ADS)

    Sánchez Almeida, J.

    2000-12-01

    The magnetic structures of the Sun are very inhomogeneous, with irregularities smaller than the smallest sizes that we resolve from Earth. Such irregularities are not properly accounted for by standard magnetic field diagnostic techniques. We have identified a quantitatively important bias that has remained unnoticed hitherto. Intense magnetic fields embedded in inhomogeneous magnetic structures produce little light and easily escape detection. These elusive magnetic fields, which cheat standard observing techniques, seem to be common. We estimate that they carry at least half of the solar magnetic flux. Should the bias be so severe, it would cast doubts on the present interpretation of many solar magnetic phenomena. Since magnetic field measurements in solar-type stars reproduce solar methods, they are liable to the same systematic errors.

  13. Isolated magnetic field structures in Mercury's magnetosheath as possible analogues for terrestrial magnetosheath plasmoids and jets

    NASA Astrophysics Data System (ADS)

    Karlsson, Tomas; Liljeblad, Elisabet; Kullen, Anita; Raines, Jim M.; Slavin, James A.; Sundberg, Torbjörn

    2016-09-01

    We have investigated MESSENGER magnetic field data from the Mercury magnetosheath and near solar wind, to identify isolated magnetic field structures (defined as clear, isolated changes in the field magnitude). Their properties are studied in order to determine if they may be considered as analogues to plasmoids and jets known to exist in Earth's magnetosheath. Both isolated decreases of the magnetic field absolute value ('negative magnetic field structures') and increases ('positive structures') are found in the magnetosheath, whereas only negative structures are found in the solar wind. The similar properties of the solar wind and magnetosheath negative magnetic field structures suggests that they are analogous to diamagnetic plasmoids found in Earth's magnetosheath and near solar wind. The latter have earlier been identified with solar wind magnetic holes. Positive magnetic field structures are only found in the magnetosheath, concentrated to a region relatively close to the magnetopause. Their proximity to the magnetopause, their scale sizes, and the association of a majority of the structures with bipolar magnetic field signatures identify them as flux transfer events (which generally are associated with a decrease of plasma density in the magnetosheath). The positive magnetic field structures are therefore not likely to be analogous to terrestrial paramagnetic plasmoids but possibly to a sub-population of magnetosheath jets. At Earth, a majority of magnetosheath jets are associated with the quasi-parallel bow shock. We discuss some consequences of the findings of the present investigation pertaining to the different nature of the quasi-parallel bow shock at Mercury and Earth.

  14. Band structure and itinerant magnetism in quantum critical NbFe2

    SciTech Connect

    Subedi, A. P.; Singh, David J

    2010-01-01

    We report first-principles calculations of the band structure and magnetic ordering in the C14 Laves phase compound NbFe{sub 2}. The magnetism is itinerant in the sense that the moments are highly dependent on ordering. We find an overestimation of the magnetic tendency within the local spin-density approximation, similar to other metals near magnetic quantum critical points. We also find a competition between different magnetic states due to band-structure effects. These lead to competing magnetic tendencies due to competing interlayer interactions, one favoring a ferrimagnetic solution and the other an antiferromagnetic state. While the structure contains Kagome lattice sheets, which could, in principle, lead to strong magnetic frustration, the calculations do not show dominant nearest-neighbor antiferromagnetic interactions within these sheets. These results are discussed in relation to experimental observations.

  15. Reconstruction of magnetic domain structure using the reverse Monte Carlo method with an extended Fourier image

    PubMed Central

    Tokii, Maki; Kita, Eiji; Mitsumata, Chiharu; Ono, Kanta; Yanagihara, Hideto

    2015-01-01

    Visualization of the magnetic domain structure is indispensable to the investigation of magnetization processes and the coercivity mechanism. It is necessary to develop a reconstruction method from the reciprocal-space image to the real-space image. For this purpose, it is necessary to solve the problem of missing phase information in the reciprocal-space image. We propose the method of extend Fourier image with mean-value padding to compensate for the phase information. We visualized the magnetic domain structure using the Reverse Monte Carlo method with simulated annealing to accelerate the calculation. With this technique, we demonstrated the restoration of the magnetic domain structure, obtained magnetization and magnetic domain width, and reproduced the characteristic form that constitutes a magnetic domain. PMID:25991875

  16. Magnetic structure at low temperatures in FeGe2

    NASA Astrophysics Data System (ADS)

    Babu, P. D.; Mishra, P. K.; Dube, V.; Mishra, R.; Sastry, P. U.; Ravikumar, G.

    2014-04-01

    Magnetic phase of FeGe2 intermetallic is studied using low-temperature neutron diffraction and DC magnetization. Zero-magnetic-field neutron scattering data shows the presence of an antiferromagnetic phase in the low temperature range. We find the evidence of the presence of a ferromagnetic order overriding on the predominantly antiferromagnetic phase at low temperatures.

  17. Radiologic atlas of pulmonary abnormalities in children

    SciTech Connect

    Singleton, E.B.; Wagner, M.L.; Dutton, R.V.

    1988-01-01

    This book is an atlas about thoracic abnormalities in infants and children. The authors include computed tomographic, digital subtraction angiographic, ultrasonographic, and a few magnetic resonance (MR) images. They recognize and discuss how changes in the medical treatment of premature infants and the management of infection and pediatric tumors have altered some of the appearances and considerations in these diseases. Oriented toward all aspects of pulmonary abnormalities, the book starts with radiographic techniques and then discusses the normal chest, the newborn, infections, tumors, and pulmonary vascular diseases. There is comprehensive treatment of mediastinal abnormalities and a discussion of airway abnormalities.

  18. Magnetic structure of R2CoGa8 (R = Gd, Tb, and Dy): Structural tuning of magnetic properties in layered Ga-based intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Mardegan, J. R. L.; Adriano, C.; Vescovi, R. F. C.; Faria, G. A.; Pagliuso, P. G.; Giles, C.

    2014-03-01

    In this work we have determined the magnetic structure of R2CoGa8 (R = Gd, Tb, and Dy) intermetallic compounds using x-ray resonant magnetic scattering in order to study the evolution of the anisotropic magnetic properties along the series for R = Gd-Tm. The three compounds have a commensurate antiferromagnetic spin structure with a magnetic propagation vector τ⃗= (1/2,1/2,1/2) and a Néel temperature of approximately 20, 28.5, and 15.2 K for R = Gd, Tb, and Dy, respectively. The critical exponent β obtained from the temperature dependence of the magnetic peaks suggest a three-dimensional universality class for the three compounds. Comparing the simulated and integrated intensities we conclude that the magnetic moment direction is in the ab plane for the Gd2CoGa8 compound and parallel to the c axis for the Tb2CoGa8 and Dy2CoGa8 compounds. The evolution of the magnetic properties of the R2CoGa8 series for R = Gd-Tm is discussed taking into account the indirect Ruderman-Kittel-Kasuya-Yoshida interaction and crystalline-electric field effects. The comparison between the reported magnetic properties of the Ga-based compounds with those for the In-based isostructural family reveals differences in their exchange couplings that contribute to the understanding of the role of the f-electron magnetism in these classes of materials.

  19. Volumetric brain abnormalities in polysubstance use disorder patients

    PubMed Central

    Noyan, Cemal Onur; Kose, Samet; Nurmedov, Serdar; Metin, Baris; Darcin, Aslı Enez; Dilbaz, Nesrin

    2016-01-01

    Aim Polysubstance users represent the largest group of patients seeking treatment at addiction and rehabilitation clinics in Turkey. There is little knowledge about the structural brain abnormalities seen in polysubstance users. This study was conducted to examine the structural brain differences between polysubstance use disorder patients and healthy control subjects using voxel-based morphometry. Methods Forty-six male polysubstance use disorder patients in the early abstinence period and 30 healthy male controls underwent structural magnetic resonance imaging scans. Voxel-based morphometry analysis was performed to examine gray matter (GM) abnormality differences. Results Polysubstance use disorder patients displayed significantly smaller GM volume in the thalamus, temporal pole, superior frontal gyrus, cerebellum, gyrus rectus, occipital lobe, anterior cingulate cortex, superior temporal gyrus, and postcentral gyrus. Conclusion A widespread and smaller GM volume has been found at different regions of the frontal, temporal, occipital, and parietal lobes, cerebellum, and anterior cingulate cortex in polysubstance users. PMID:27358566

  20. Structure of transformer oil-based magnetic fluids studied using acoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Kúdelčík, Jozef; Bury, Peter; Drga, Jozef; Kopčanský, Peter; Závišová, Vlasta; Timko, Milan

    2013-01-01

    The structural changes in transformer oil-based magnetic fluids upon the effect of an external magnetic field and temperature were studied by acoustic spectroscopy. The attenuation of acoustic wave was measured as a function of the magnetic field in the range of 0-300 mT and in the temperature range of 15-35 °C for various magnetic nanoparticles concentrations. The effect of anisotropy of the acoustic attenuation was determined, too. The both strong influence of the magnetic field on the acoustic attenuation and its hysteresis were observed. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs, leading to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids also has very important influence on the structural changes because of the mechanism of thermal motion that acts against the cluster creation. The observed influences of both magnetic field and temperature on the investigated magnetic fluid structure are discussed.